[RFC v5] fuse: containerize ext4 for safer operation

[RFC v5] fuse: containerize ext4 for safer operation

[Darrick J. Wong]

Hi everyone,

[Ok maybe it's time to merge some of this stuff.  I'm removing the RFC
tag, but most likely the only patches that should get merged at this
point are the bugfixes at the start.  Don't merge the rest until after
the 2025 LTS kernel merge window closes, please.]

This is the fifth public draft of a prototype to connect the Linux fuse
driver to fs-iomap for regular file IO operations to and from files
whose contents persist to locally attached storage devices.  With this
release, I show that it's possible to build a fuse server for a real
filesystem (ext4) that runs entirely in userspace yet maintains most of
its performance.  Furthermore, I also show that the userspace program
runs with minimal privilege, which means that we no longer need to have
filesystem metadata parsing be a privileged (== risky) operation.

Why would you want to do that?  Most filesystem drivers are seriously
vulnerable to metadata parsing attacks, as syzbot has shown repeatedly
over almost a decade of its existence.  Faulty code can lead to total
kernel compromise, and I think there's a very strong incentive to move
all that parsing out to userspace where we can containerize the fuse
server process.

willy's folios conversion project (and to a certain degree RH's new
mount API) have also demonstrated that treewide changes to the core
mm/pagecache/fs code are very very difficult to pull off and take years
because you have to understand every filesystem's bespoke use of that
core code.  Eeeugh.

The fuse command plumbing is very simple -- the ->iomap_begin,
->iomap_end, and iomap ->ioend calls within iomap are turned into
upcalls to the fuse server via a trio of new fuse commands.  Pagecache
writeback is now a directio write.  The fuse server is now able to
upsert mappings into the kernel for cached access (== zero upcalls for
rereads and pure overwrites!) and the iomap cache revalidation code
works.

At this stage I still get about 95% of the kernel ext4 driver's
streaming directio performance on streaming IO, and 110% of its
streaming buffered IO performance.  Random buffered IO is about 85% as
fast as the kernel.  Random direct IO is about 80% as fast as the
kernel; see the cover letter for the fuse2fs iomap changes for more
details.  Unwritten extent conversions on random direct writes are
especially painful for fuse+iomap (~90% more overhead) due to upcall
overhead.  And that's with (now dynamic) debugging turned on!

These items have been addressed since the fourth RFC:

1. After six months, I have achieved my primary goal: a containerized
   filesystem server!  We can now run fuse4fs as a completely
   unprivileged and namespace-restricted systemd service on behalf of
   anyone who can open a file and mount it.  Many thanks again to
   Christian (and Miklos and Bernd and Amir) for their help!

   Someone who knows how to design socket-based protocols ought to have
   a look at the libfuse changes.  The mount helper and the fuse server
   communicate via a AF_UNIX socket, which enables the mount helper to
   pass resources into the service container.

2. I took a stab at implementing fsdax.  I then encountered the horror
   that is dax_writeback_mapping_range and abandoned that work.
   Writeback needs to iterate the file mappings and not make assumptions
   about the backing device ... but that's not a problem that anyone
   here needs to solve.

3. struct fuse_inode shrank after I verified that the iomap fileio paths
   never have to venture into the regular or wb cache paths.

4. fstests passes 99% of the tests that run, when iomap is enabled!
   96% pass when iomap is disabled, and I think that's due to some
   bugs in fstests.

5. Some VFS iflags (sync/immutable/append) now work.

6. iomap and passthrough share the backing file management code.  They
   are not expected to share backing files.

There are some major warts remaining:

a. I would like to start a discussion about how the design review of
   this code should be structured, and how might I go about creating new
   userspace filesystem servers -- lightweight new ones based off the
   existing userspace tools?  Or by merging lklfuse?

b. No design review document yet.

c. Why aren't we at 100% fstests passing?  Even with the kernel ext4?

d. I'm not 100% certain that the code that handles EOF zeroing actually
   works correctly.  Does fuse+iomap need to track both the server's
   and the VFS' notion of EOF the same way that XFS does?

e. ext4 doesn't support out of place writes so I don't know if that
   actually works correctly.

f. fuse2fs doesn't support the ext4 journal.  Urk.

g. There's a VERY large quantity of fuse2fs improvements that need to be
   applied before we get to the fuse-iomap parts.  I'm not sending these
   (or the fstests changes) to keep the size of the patchbomb at
   "unreasonably large". :P

I'll work on these in October, but now you all have an alpha-complete
demonstration to take a look at.

--Darrick

[PATCHSET RFC v5 1/8] fuse: general bug fixes

[Darrick J. Wong]

Hi all,

Here's a collection of fixes that I *think* are bugs in fuse, along with
some scattered improvements.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-fixes
---
Commits in this patchset:
 * fuse: fix livelock in synchronous file put from fuseblk workers
 * fuse: flush pending fuse events before aborting the connection
 * fuse: capture the unique id of fuse commands being sent
 * fuse: signal that a fuse filesystem should exhibit local fs behaviors
 * fuse: implement file attributes mask for statx
 * fuse: update file mode when updating acls
 * fuse: propagate default and file acls on creation
 * fuse: enable FUSE_SYNCFS for all fuseblk servers
---
 fs/fuse/fuse_i.h    |   55 +++++++++++++++++++++++++++
 fs/fuse/acl.c       |  105 +++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/dev.c       |   60 +++++++++++++++++++++++++++--
 fs/fuse/dev_uring.c |    4 +-
 fs/fuse/dir.c       |   96 +++++++++++++++++++++++++++++++++++------------
 fs/fuse/file.c      |    8 +++-
 fs/fuse/inode.c     |   17 ++++++++
 fs/fuse/virtio_fs.c |    3 -
 8 files changed, 314 insertions(+), 34 deletions(-)

[PATCHSET RFC v5 2/8] iomap: cleanups ahead of adding fuse support

[Darrick J. Wong]

Hi all,

In preparation for making fuse use the fs/iomap code for regular file
data IO, fix a few bugs in fuse and apply a couple of tweaks to iomap.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=iomap-fuse-prep
---
Commits in this patchset:
 * iomap: trace iomap_zero_iter zeroing activities
 * iomap: error out on file IO when there is no inline_data buffer
---
 fs/iomap/trace.h       |    1 +
 fs/iomap/buffered-io.c |   18 +++++++++++++-----
 fs/iomap/direct-io.c   |    3 +++
 3 files changed, 17 insertions(+), 5 deletions(-)

[PATCHSET RFC v5 3/8] fuse: cleanups ahead of adding fuse support

[Darrick J. Wong]

Hi all,

In preparation for making fuse use the fs/iomap code for regular file
data IO, fix a few bugs in fuse and apply a couple of tweaks to iomap.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-iomap-prep
---
Commits in this patchset:
 * fuse: allow synchronous FUSE_INIT
 * fuse: move the backing file idr and code into a new source file
 * fuse: move the passthrough-specific code back to passthrough.c
 * fuse_trace: move the passthrough-specific code back to passthrough.c
 * fuse: move CREATE_TRACE_POINTS to a separate file
---
 fs/fuse/fuse_dev_i.h      |   13 ++-
 fs/fuse/fuse_i.h          |   73 ++++++++++----
 fs/fuse/fuse_trace.h      |   35 +++++++
 include/uapi/linux/fuse.h |    9 ++
 fs/fuse/Kconfig           |    4 +
 fs/fuse/Makefile          |    4 +
 fs/fuse/backing.c         |  231 +++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/cuse.c            |    3 -
 fs/fuse/dev.c             |   79 +++++++++++----
 fs/fuse/dev_uring.c       |    4 -
 fs/fuse/inode.c           |   54 ++++++++---
 fs/fuse/passthrough.c     |  198 +++++++--------------------------------
 fs/fuse/trace.c           |   13 +++
 13 files changed, 494 insertions(+), 226 deletions(-)
 create mode 100644 fs/fuse/backing.c
 create mode 100644 fs/fuse/trace.c

[PATCHSET RFC v5 4/8] fuse: allow servers to use iomap for better file IO performance

[Darrick J. Wong]

Hi all,

This series connects fuse (the userspace filesystem layer) to fs-iomap
to get fuse servers out of the business of handling file I/O themselves.
By keeping the IO path mostly within the kernel, we can dramatically
improve the speed of disk-based filesystems.  This enables us to move
all the filesystem metadata parsing code out of the kernel and into
userspace, which means that we can containerize them for security
without losing a lot of performance.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-iomap-fileio
---
Commits in this patchset:
 * fuse: implement the basic iomap mechanisms
 * fuse_trace: implement the basic iomap mechanisms
 * fuse: make debugging configurable at runtime
 * fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices
 * fuse_trace: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices
 * fuse: flush events and send FUSE_SYNCFS and FUSE_DESTROY on unmount
 * fuse: create a per-inode flag for toggling iomap
 * fuse_trace: create a per-inode flag for toggling iomap
 * fuse: isolate the other regular file IO paths from iomap
 * fuse: implement basic iomap reporting such as FIEMAP and SEEK_{DATA,HOLE}
 * fuse_trace: implement basic iomap reporting such as FIEMAP and SEEK_{DATA,HOLE}
 * fuse: implement direct IO with iomap
 * fuse_trace: implement direct IO with iomap
 * fuse: implement buffered IO with iomap
 * fuse_trace: implement buffered IO with iomap
 * fuse: implement large folios for iomap pagecache files
 * fuse: use an unrestricted backing device with iomap pagecache io
 * fuse: advertise support for iomap
 * fuse: query filesystem geometry when using iomap
 * fuse_trace: query filesystem geometry when using iomap
 * fuse: implement fadvise for iomap files
 * fuse: invalidate ranges of block devices being used for iomap
 * fuse_trace: invalidate ranges of block devices being used for iomap
 * fuse: implement inline data file IO via iomap
 * fuse_trace: implement inline data file IO via iomap
 * fuse: allow more statx fields
 * fuse: support atomic writes with iomap
 * fuse: disable direct reclaim for any fuse server that uses iomap
---
 fs/fuse/fuse_i.h          |  172 ++++
 fs/fuse/fuse_trace.h      |  936 +++++++++++++++++++
 fs/fuse/iomap_priv.h      |   52 +
 include/uapi/linux/fuse.h |  201 ++++
 fs/fuse/Kconfig           |   48 +
 fs/fuse/Makefile          |    1 
 fs/fuse/backing.c         |   12 
 fs/fuse/dev.c             |   30 +
 fs/fuse/dir.c             |  120 ++
 fs/fuse/file.c            |  133 ++-
 fs/fuse/file_iomap.c      | 2165 +++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/inode.c           |   66 +
 fs/fuse/iomode.c          |    2 
 fs/fuse/trace.c           |    2 
 14 files changed, 3892 insertions(+), 48 deletions(-)
 create mode 100644 fs/fuse/iomap_priv.h
 create mode 100644 fs/fuse/file_iomap.c

[PATCHSET RFC v5 5/8] fuse: allow servers to specify root node id

[Darrick J. Wong]

Hi all,

This series grants fuse servers full control over the entire node id
address space by allowing them to specify the nodeid of the root
directory.  With this new feature, fuse4fs will not have to translate
node ids.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-root-nodeid
---
Commits in this patchset:
 * fuse: make the root nodeid dynamic
 * fuse_trace: make the root nodeid dynamic
 * fuse: allow setting of root nodeid
---
 fs/fuse/fuse_i.h     |    9 +++++++--
 fs/fuse/fuse_trace.h |    6 ++++--
 fs/fuse/dir.c        |   10 ++++++----
 fs/fuse/inode.c      |   22 ++++++++++++++++++----
 fs/fuse/readdir.c    |   10 +++++-----
 5 files changed, 40 insertions(+), 17 deletions(-)

[PATCHSET RFC v5 6/8] fuse: handle timestamps and ACLs correctly when iomap is enabled

[Darrick J. Wong]

Hi all,

When iomap is enabled for a fuse file, we try to keep as much of the
file IO path in the kernel as we possibly can.  That means no calling
out to the fuse server in the IO path when we can avoid it.  However,
the existing FUSE architecture defers all file attributes to the fuse
server -- [cm]time updates, ACL metadata management, set[ug]id removal,
and permissions checking thereof, etc.

We'd really rather do all these attribute updates in the kernel, and
only push them to the fuse server when it's actually necessary (e.g.
fsync).  Furthermore, the POSIX ACL code has the weird behavior that if
the access ACL can be represented entirely by i_mode bits, it will
change the mode and delete the ACL, which fuse servers generally don't
seem to implement.

IOWs, we want consistent and correct (as defined by fstests) behavior
of file attributes in iomap mode.  Let's make the kernel manage all that
and push the results to userspace as needed.  This improves performance
even further, since it's sort of like writeback_cache mode but more
aggressive.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-iomap-attrs
---
Commits in this patchset:
 * fuse: enable caching of timestamps
 * fuse: force a ctime update after a fileattr_set call when in iomap mode
 * fuse: allow local filesystems to set some VFS iflags
 * fuse_trace: allow local filesystems to set some VFS iflags
 * fuse: cache atime when in iomap mode
 * fuse: let the kernel handle KILL_SUID/KILL_SGID for iomap filesystems
 * fuse_trace: let the kernel handle KILL_SUID/KILL_SGID for iomap filesystems
 * fuse: update ctime when updating acls on an iomap inode
 * fuse: always cache ACLs when using iomap
---
 fs/fuse/fuse_i.h          |    1 +
 fs/fuse/fuse_trace.h      |   87 +++++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/fuse.h |    8 ++++
 fs/fuse/acl.c             |   29 +++++++++++++--
 fs/fuse/dir.c             |   38 ++++++++++++++++----
 fs/fuse/file.c            |   18 ++++++---
 fs/fuse/file_iomap.c      |    6 +++
 fs/fuse/inode.c           |   27 +++++++++++---
 fs/fuse/ioctl.c           |   70 ++++++++++++++++++++++++++++++++++++
 fs/fuse/readdir.c         |    3 +-
 10 files changed, 263 insertions(+), 24 deletions(-)

[PATCHSET RFC v5 7/8] fuse: cache iomap mappings for even better file IO performance

[Darrick J. Wong]

Hi all,

This series improves the performance (and correctness for some
filesystems) by adding the ability to cache iomap mappings in the
kernel.  For filesystems that can change mapping states during pagecache
writeback (e.g. unwritten extent conversion) this is absolutely
necessary to deal with races with writes to the pagecache because
writeback does not take i_rwsem.  For everyone else, it simply
eliminates roundtrips to userspace.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-iomap-cache
---
Commits in this patchset:
 * fuse: cache iomaps
 * fuse_trace: cache iomaps
 * fuse: use the iomap cache for iomap_begin
 * fuse_trace: use the iomap cache for iomap_begin
 * fuse: invalidate iomap cache after file updates
 * fuse_trace: invalidate iomap cache after file updates
 * fuse: enable iomap cache management
 * fuse_trace: enable iomap cache management
 * fuse: overlay iomap inode info in struct fuse_inode
 * fuse: enable iomap
---
 fs/fuse/fuse_i.h          |   58 ++
 fs/fuse/fuse_trace.h      |  434 ++++++++++++
 fs/fuse/iomap_priv.h      |  149 ++++
 include/uapi/linux/fuse.h |   33 +
 fs/fuse/Makefile          |    2 
 fs/fuse/dev.c             |   44 +
 fs/fuse/dir.c             |    6 
 fs/fuse/file.c            |   10 
 fs/fuse/file_iomap.c      |  527 ++++++++++++++
 fs/fuse/iomap_cache.c     | 1693 +++++++++++++++++++++++++++++++++++++++++++++
 10 files changed, 2937 insertions(+), 19 deletions(-)
 create mode 100644 fs/fuse/iomap_cache.c

[PATCHSET RFC v5 8/8] fuse: run fuse servers as a contained service

[Darrick J. Wong]

Hi all,

This patchset defines the necessary communication protocols and library
code so that users can mount fuse servers that run in unprivileged
systemd service containers.  That in turn allows unprivileged untrusted
mounts, because the worst that can happen is that a malicious image
crashes the fuse server and the mount dies, instead of corrupting the
kernel.  As part of the delegation, add a new ioctl allowing any process
with an open fusedev fd to ask for permission for anyone with that
fusedev fd to use iomap.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-service-container
---
Commits in this patchset:
 * fuse: allow privileged mount helpers to pre-approve iomap usage
 * fuse: set iomap backing device block size
---
 fs/fuse/fuse_dev_i.h      |   32 +++++++++++++++++++--
 fs/fuse/fuse_i.h          |   12 ++++++++
 include/uapi/linux/fuse.h |    8 +++++
 fs/fuse/dev.c             |   13 +++++----
 fs/fuse/file_iomap.c      |   67 ++++++++++++++++++++++++++++++++++++++++++++-
 fs/fuse/inode.c           |   18 ++++++++----
 6 files changed, 134 insertions(+), 16 deletions(-)

[PATCHSET RFC v5 1/6] libfuse: general bug fixes

[Darrick J. Wong]

Hi all,

Here's a collection of fixes that I *think* are bugs in libfuse.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

With a bit of luck, this should all go splendidly.
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-fixes
---
Commits in this patchset:
 * libfuse: don't put HAVE_STATX in a public header
---
 include/fuse.h           |    2 --
 include/fuse_lowlevel.h  |    2 --
 example/memfs_ll.cc      |    2 +-
 example/passthrough.c    |    2 +-
 example/passthrough_fh.c |    2 +-
 example/passthrough_ll.c |    2 +-
 6 files changed, 4 insertions(+), 8 deletions(-)

[PATCHSET RFC v5 2/6] libfuse: allow servers to use iomap for better file IO performance

[Darrick J. Wong]

Hi all,

This series connects libfuse to the iomap-enabled fuse driver in Linux to get
fuse servers out of the business of handling file I/O themselves.  By keeping
the IO path mostly within the kernel, we can dramatically improve the speed of
disk-based filesystems.  This enables us to move all the filesystem metadata
parsing code out of the kernel and into userspace, which means that we can
containerize them for security without losing a lot of performance.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

With a bit of luck, this should all go splendidly.
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-iomap-fileio
---
Commits in this patchset:
 * libfuse: bump kernel and library ABI versions
 * libfuse: add kernel gates for FUSE_IOMAP
 * libfuse: add fuse commands for iomap_begin and end
 * libfuse: add upper level iomap commands
 * libfuse: add a lowlevel notification to add a new device to iomap
 * libfuse: add upper-level iomap add device function
 * libfuse: add iomap ioend low level handler
 * libfuse: add upper level iomap ioend commands
 * libfuse: add a reply function to send FUSE_ATTR_* to the kernel
 * libfuse: connect high level fuse library to fuse_reply_attr_iflags
 * libfuse: support direct I/O through iomap
 * libfuse: don't allow hardlinking of iomap files in the upper level fuse library
 * libfuse: allow discovery of the kernel's iomap capabilities
 * libfuse: add lower level iomap_config implementation
 * libfuse: add upper level iomap_config implementation
 * libfuse: add low level code to invalidate iomap block device ranges
 * libfuse: add upper-level API to invalidate parts of an iomap block device
 * libfuse: add atomic write support
---
 include/fuse.h          |   86 ++++++++
 include/fuse_common.h   |  136 +++++++++++++
 include/fuse_kernel.h   |  118 +++++++++++
 include/fuse_lowlevel.h |  243 ++++++++++++++++++++++++
 ChangeLog.rst           |   12 +
 lib/fuse.c              |  484 ++++++++++++++++++++++++++++++++++++++++++-----
 lib/fuse_lowlevel.c     |  377 +++++++++++++++++++++++++++++++++++--
 lib/fuse_versionscript  |   20 ++
 lib/meson.build         |    2 
 meson.build             |    2 
 10 files changed, 1405 insertions(+), 75 deletions(-)

[PATCHSET RFC v5 3/6] libfuse: allow servers to specify root node id

[Darrick J. Wong]

Hi all,

This series grants fuse servers full control over the entire node id
address space by allowing them to specify the nodeid of the root
directory.  With this new feature, fuse4fs will not have to translate
node ids.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

With a bit of luck, this should all go splendidly.
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-root-nodeid
---
Commits in this patchset:
 * libfuse: allow root_nodeid mount option
---
 lib/mount.c |    1 +
 1 file changed, 1 insertion(+)

[PATCHSET RFC v5 4/6] libfuse: implement syncfs

[Darrick J. Wong]

Hi all,

Implement syncfs in libfuse so that iomap-compatible fuse servers can
receive syncfs commands, and enable fuse servers to transmit inode
flags to the kernel so that it can enforce sync, immutable, and append.
Also enable some of the timestamp update mount options.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

With a bit of luck, this should all go splendidly.
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-iomap-attrs
---
Commits in this patchset:
 * libfuse: add strictatime/lazytime mount options
 * libfuse: set sync, immutable, and append when loading files
 * libfuse: wire up FUSE_SYNCFS to the low level library
 * libfuse: add syncfs support to the upper library
---
 include/fuse.h          |    5 +++++
 include/fuse_common.h   |    6 ++++++
 include/fuse_kernel.h   |    8 ++++++++
 include/fuse_lowlevel.h |   16 ++++++++++++++++
 lib/fuse.c              |   31 +++++++++++++++++++++++++++++++
 lib/fuse_lowlevel.c     |   25 +++++++++++++++++++++++++
 lib/mount.c             |   18 ++++++++++++++++--
 7 files changed, 107 insertions(+), 2 deletions(-)

[PATCHSET RFC v5 5/6] libfuse: cache iomap mappings for even better file IO performance

[Darrick J. Wong]

Hi all,

This series improves the performance (and correctness for some
filesystems) by adding the ability to cache iomap mappings in the
kernel.  For filesystems that can change mapping states during pagecache
writeback (e.g. unwritten extent conversion) this is absolutely
necessary to deal with races with writes to the pagecache because
writeback does not take i_rwsem.  For everyone else, it simply
eliminates roundtrips to userspace.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

With a bit of luck, this should all go splendidly.
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-iomap-cache
---
Commits in this patchset:
 * libfuse: enable iomap cache management for lowlevel fuse
 * libfuse: add upper-level iomap cache management
 * libfuse: enable iomap
---
 include/fuse.h          |   31 +++++++++++++++++++
 include/fuse_common.h   |   12 ++++++++
 include/fuse_kernel.h   |   26 ++++++++++++++++
 include/fuse_lowlevel.h |   41 ++++++++++++++++++++++++++
 lib/fuse.c              |   30 +++++++++++++++++++
 lib/fuse_lowlevel.c     |   75 ++++++++++++++++++++++++++++++++++++++++++++++-
 lib/fuse_versionscript  |    4 +++
 7 files changed, 217 insertions(+), 2 deletions(-)

[PATCHSET RFC v5 6/6] libfuse: run fuse servers as a contained service

[Darrick J. Wong]

Hi all,

This patchset defines the necessary communication protocols and library
code so that users can mount fuse servers that run in unprivileged
systemd service containers.  That in turn allows unprivileged untrusted
mounts, because the worst that can happen is that a malicious image
crashes the fuse server and the mount dies, instead of corrupting the
kernel.  As part of the delegation, add a new ioctl allowing any process
with an open fusedev fd to ask for permission for anyone with that
fusedev fd to use iomap.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

With a bit of luck, this should all go splendidly.
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=fuse-service-container
---
Commits in this patchset:
 * libfuse: add systemd/inetd socket service mounting helper
 * libfuse: integrate fuse services into mount.fuse3
 * libfuse: delegate iomap privilege from mount.service to fuse services
 * libfuse: enable setting iomap block device block size
---
 include/fuse_kernel.h       |    8 
 include/fuse_lowlevel.h     |   23 +
 include/fuse_service.h      |  162 +++++++
 include/fuse_service_priv.h |  108 ++++
 lib/fuse_i.h                |    5 
 util/mount_service.h        |   41 ++
 doc/fuservicemount3.8       |   32 +
 doc/meson.build             |    3 
 include/meson.build         |    4 
 lib/fuse_lowlevel.c         |   16 +
 lib/fuse_service.c          |  813 +++++++++++++++++++++++++++++++++
 lib/fuse_service_stub.c     |   90 ++++
 lib/fuse_versionscript      |   16 +
 lib/helper.c                |   53 ++
 lib/meson.build             |   14 +
 lib/mount.c                 |   57 ++
 meson.build                 |   36 +
 meson_options.txt           |    6 
 util/fuservicemount.c       |   66 +++
 util/meson.build            |   13 -
 util/mount.fuse.c           |   58 ++
 util/mount_service.c        | 1044 +++++++++++++++++++++++++++++++++++++++++++
 22 files changed, 2631 insertions(+), 37 deletions(-)
 create mode 100644 include/fuse_service.h
 create mode 100644 include/fuse_service_priv.h
 create mode 100644 util/mount_service.h
 create mode 100644 doc/fuservicemount3.8
 create mode 100644 lib/fuse_service.c
 create mode 100644 lib/fuse_service_stub.c
 create mode 100644 util/fuservicemount.c
 create mode 100644 util/mount_service.c

[PATCHSET RFC v5 2/9] fuse4fs: fork a low level fuse server

[Darrick J. Wong]

Hi all,

Whilst developing the fuse2fs+iomap prototype, I discovered a
fundamental design limitation of the upper-level libfuse API: hardlinks.
The upper level fuse library really wants to communicate with the fuse
server with file paths, instead of using inode numbers.  This works
great for filesystems that don't have inodes, create files dynamically
at runtime, or lack stable inode numbers.

Unfortunately, the libfuse path abstraction assigns a unique nodeid to
every child file in the entire filesystem, without regard to hard links.
In other words, a hardlinked regular file may have one ondisk inode
number but multiple kernel inodes.  For classic fuse2fs this isn't a
problem because all file access goes through the fuse server and the big
library lock protects us from corruption.

For fuse2fs + iomap this is a disaster because we rely on the kernel to
coordinate access to inodes.  For hardlinked files, we *require* that
there only be one in-kernel inode for each ondisk inode.

The path based mechanism is also very inefficient for fuse2fs.  Every
time a file is accessed, the upper level libfuse passes a new nodeid to
the kernel, and on every file access the kernel passes that same nodeid
back to libfuse.  libfuse then walks its internal directory entry cache
to construct a path string for that nodeid and hands it to fuse2fs.
fuse2fs then walks the ondisk directory structure to find the ext2 inode
number.  Every time.

Create a new fuse4fs server from fuse2fs that uses the lowlevel fuse
API.  This affords us direct control over nodeids and eliminates the
path wrangling.  Hardlinks can be supported when iomap is turned on,
and metadata-heavy workloads run twice as fast.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=fuse4fs-fork
---
Commits in this patchset:
 * fuse2fs: separate libfuse3 and fuse2fs detection in configure
 * fuse2fs: start porting fuse2fs to lowlevel libfuse API
 * debian: create new package for fuse4fs
 * fuse4fs: namespace some helpers
 * fuse4fs: convert to low level API
 * libsupport: port the kernel list.h to libsupport
 * libsupport: add a cache
 * cache: disable debugging
 * cache: use modern list iterator macros
 * cache: embed struct cache in the owner
 * cache: pass cache pointer to callbacks
 * cache: pass a private data pointer through cache_walk
 * cache: add a helper to grab a new refcount for a cache_node
 * cache: return results of a cache flush
 * cache: add a "get only if incore" flag to cache_node_get
 * cache: support gradual expansion
 * cache: implement automatic shrinking
 * fuse4fs: add cache to track open files
 * fuse4fs: use the orphaned inode list
 * fuse4fs: implement FUSE_TMPFILE
 * fuse4fs: create incore reverse orphan list
---
 lib/ext2fs/jfs_compat.h  |    2 
 lib/ext2fs/kernel-list.h |  111 -
 lib/support/cache.h      |  177 +
 lib/support/list.h       |  901 +++++++
 lib/support/xbitops.h    |  128 +
 Makefile.in              |    3 
 configure                |  414 +--
 configure.ac             |  156 +
 debian/control           |   12 
 debian/fuse4fs.install   |    2 
 debian/rules             |   11 
 debugfs/Makefile.in      |   12 
 e2fsck/Makefile.in       |   56 
 fuse4fs/Makefile.in      |  193 +
 fuse4fs/fuse4fs.1.in     |  118 +
 fuse4fs/fuse4fs.c        | 6169 ++++++++++++++++++++++++++++++++++++++++++++++
 lib/config.h.in          |    3 
 lib/e2p/Makefile.in      |    4 
 lib/ext2fs/Makefile.in   |   14 
 lib/support/Makefile.in  |    8 
 lib/support/cache.c      |  853 ++++++
 misc/Makefile.in         |   18 
 misc/tune2fs.c           |    4 
 23 files changed, 8922 insertions(+), 447 deletions(-)
 delete mode 100644 lib/ext2fs/kernel-list.h
 create mode 100644 lib/support/cache.h
 create mode 100644 lib/support/list.h
 create mode 100644 lib/support/xbitops.h
 create mode 100644 debian/fuse4fs.install
 create mode 100644 fuse4fs/Makefile.in
 create mode 100644 fuse4fs/fuse4fs.1.in
 create mode 100644 fuse4fs/fuse4fs.c
 create mode 100644 lib/support/cache.c

[PATCHSET RFC v5 3/9] libext2fs: refactoring for fuse2fs iomap support

[Darrick J. Wong]

Hi all,

In preparation for connecting fuse, iomap, and fuse2fs for a much more
performant file IO path, make some changes to the Unix IO manager in
libext2fs so that we can have better IO.  First we start by making
filesystem flushes a lot more efficient by eliding fsyncs when they're
not necessary, and allowing library clients to turn off the racy code
that writes the superblock byte by byte but exposes stale checksums.

XXX: The second part of this series adds IO tagging so that we could tag
IOs by inode number to distinguish file data blocks in cache from
everything else.  This is temporary scaffolding whilst we're in the
middle adding directio and later buffered writes.  Once we can use the
pagecache for all file IO activity I think we could drop the back half
of this series.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=libext2fs-iomap-prep
---
Commits in this patchset:
 * libext2fs: make it possible to extract the fd from an IO manager
 * libext2fs: always fsync the device when flushing the cache
 * libext2fs: always fsync the device when closing the unix IO manager
 * libext2fs: only fsync the unix fd if we wrote to the device
 * libext2fs: invalidate cached blocks when freeing them
 * libext2fs: only flush affected blocks in unix_write_byte
 * libext2fs: allow unix_write_byte when the write would be aligned
 * libext2fs: allow clients to ask to write full superblocks
 * libext2fs: allow callers to disallow I/O to file data blocks
 * libext2fs: add posix advisory locking to the unix IO manager
---
 lib/ext2fs/ext2_io.h         |   10 ++
 lib/ext2fs/ext2fs.h          |    4 +
 debian/libext2fs2t64.symbols |    2 
 lib/ext2fs/alloc_stats.c     |    6 +
 lib/ext2fs/closefs.c         |    7 ++
 lib/ext2fs/fileio.c          |   12 +++
 lib/ext2fs/io_manager.c      |   17 ++++
 lib/ext2fs/unix_io.c         |  180 ++++++++++++++++++++++++++++++++++++++++--
 8 files changed, 228 insertions(+), 10 deletions(-)

[PATCHSET RFC v5 4/9] fuse2fs: use fuse iomap data paths for better file I/O performance

[Darrick J. Wong]

Hi all,

Switch fuse2fs to use the new iomap file data IO paths instead of
pushing it very slowly through the /dev/fuse connection.  For local
filesystems, all we have to do is respond to requests for file to device
mappings; the rest of the IO hot path stays within the kernel.  This
means that we can get rid of all file data block processing within
fuse2fs.

Because we're not pinning dirty pages through a potentially slow network
connection, we don't need the heavy BDI throttling for which most fuse
servers have become infamous.  Yes, mapping lookups for writeback can
stall, but mappings are small as compared to data and this situation
exists for all kernel filesystems as well.

The performance of this new data path is quite stunning: on a warm
system, streaming reads and writes through the pagecache go from
60-90MB/s to 2-2.5GB/s.  Direct IO reads and writes improve from the
same baseline to 2.5-8GB/s.  FIEMAP and SEEK_DATA/SEEK_HOLE now work
too.  The kernel ext4 driver can manage about 1.6GB/s for pagecache IO
and about 2.6-8.5GB/s, which means that fuse2fs is about as fast as the
kernel for streaming file IO.

Random 4k buffered IO is not so good: plain fuse2fs pokes along at
25-50MB/s, whereas fuse2fs with iomap manages 90-1300MB/s.  The kernel
can do 900-1300MB/s.  Random directio is worse: plain fuse2fs does
20-30MB/s, fuse-iomap does about 30-35MB/s, and the kernel does
40-55MB/s.  I suspect that metadata heavy workloads do not perform well
on fuse2fs because libext2fs wasn't designed for that and it doesn't
even have a journal to absorb all the fsync writes.  We also probably
need iomap caching really badly.

These performance numbers are slanted: my machine is 12 years old, and
fuse2fs is VERY poorly optimized for performance.  It contains a single
Big Filesystem Lock which nukes multi-threaded scalability.  There's no
inode cache nor is there a proper buffer cache, which means that fuse2fs
reads metadata in from disk and checksums it on EVERY ACCESS.  Sad!

Despite these gaps, this RFC demonstrates that it's feasible to run the
metadata parsing parts of a filesystem in userspace while not
sacrificing much performance.  We now have a vehicle to move the
filesystems out of the kernel, where they can be containerized so that
malicious filesystems can be contained, somewhat.

iomap mode also calls FUSE_DESTROY before unmounting the filesystem, so
for capable systems, fuse2fs doesn't need to run in fuseblk mode
anymore.

However, there are some major warts remaining:

1. The iomap cookie validation is not present, which can lead to subtle
races between pagecache zeroing and writeback on filesystems that
support unwritten and delalloc mappings.

2. Mappings ought to be cached in the kernel for more speed.

3. iomap doesn't support things like fscrypt or fsverity, and I haven't
yet figured out how inline data is supposed to work.

4. I would like to be able to turn on fuse+iomap on a per-inode basis,
which currently isn't possible because the kernel fuse driver will iget
inodes prior to calling FUSE_GETATTR to discover the properties of the
inode it just read.

5. ext4 doesn't support out of place writes so I don't know if that
actually works correctly.

6. iomap is an inode-based service, not a file-based service.  This
means that we /must/ push ext2's inode numbers into the kernel via
FUSE_GETATTR so that it can report those same numbers back out through
the FUSE_IOMAP_* calls.  However, the fuse kernel uses a separate nodeid
to index its incore inode, so we have to pass those too so that
notifications work properly.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=fuse2fs-iomap-fileio
---
Commits in this patchset:
 * fuse2fs: implement bare minimum iomap for file mapping reporting
 * fuse2fs: add iomap= mount option
 * fuse2fs: implement iomap configuration
 * fuse2fs: register block devices for use with iomap
 * fuse2fs: implement directio file reads
 * fuse2fs: add extent dump function for debugging
 * fuse2fs: implement direct write support
 * fuse2fs: turn on iomap for pagecache IO
 * fuse2fs: don't zero bytes in punch hole
 * fuse2fs: don't do file data block IO when iomap is enabled
 * fuse2fs: avoid fuseblk mode if fuse-iomap support is likely
 * fuse2fs: enable file IO to inline data files
 * fuse2fs: set iomap-related inode flags
 * fuse2fs: configure block device block size
 * fuse4fs: separate invalidation
 * fuse2fs: implement statx
 * fuse2fs: enable atomic writes
---
 configure            |   48 +
 configure.ac         |   31 +
 fuse4fs/fuse4fs.1.in |    6 
 fuse4fs/fuse4fs.c    | 1690 +++++++++++++++++++++++++++++++++++++++++++++++-
 lib/config.h.in      |    3 
 misc/fuse2fs.1.in    |    6 
 misc/fuse2fs.c       | 1755 ++++++++++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 3503 insertions(+), 36 deletions(-)

[PATCHSET RFC v5 5/9] fuse4fs: specify the root node id

[Darrick J. Wong]

Hi all,


If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=fuse2fs-root-nodeid
---
Commits in this patchset:
 * fuse4fs: don't use inode number translation when possible
---
 fuse4fs/fuse4fs.c |   29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

[PATCHSET RFC v5 6/9] fuse2fs: handle timestamps and ACLs correctly when iomap is enabled

[Darrick J. Wong]

Hi all,

When iomap is enabled for a fuse file, we try to keep as much of the
file IO path in the kernel as we possibly can.  That means no calling
out to the fuse server in the IO path when we can avoid it.  However,
the existing FUSE architecture defers all file attributes to the fuse
server -- [cm]time updates, ACL metadata management, set[ug]id removal,
and permissions checking thereof, etc.

We'd really rather do all these attribute updates in the kernel, and
only push them to the fuse server when it's actually necessary (e.g.
fsync).  Furthermore, the POSIX ACL code has the weird behavior that if
the access ACL can be represented entirely by i_mode bits, it will
change the mode and delete the ACL, which fuse servers generally don't
seem to implement.

IOWs, we want consistent and correct (as defined by fstests) behavior
of file attributes in iomap mode.  Let's make the kernel manage all that
and push the results to userspace as needed.  This improves performance
even further, since it's sort of like writeback_cache mode but more
aggressive.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=fuse2fs-iomap-attrs
---
Commits in this patchset:
 * fuse2fs: add strictatime/lazytime mount options
 * fuse2fs: skip permission checking on utimens when iomap is enabled
 * fuse2fs: let the kernel tell us about acl/mode updates
 * fuse2fs: better debugging for file mode updates
 * fuse2fs: debug timestamp updates
 * fuse2fs: use coarse timestamps for iomap mode
 * fuse2fs: add tracing for retrieving timestamps
 * fuse2fs: enable syncfs
 * fuse2fs: skip the gdt write in op_destroy if syncfs is working
 * fuse2fs: set sync, immutable, and append at file load time
---
 fuse4fs/fuse4fs.1.in |    6 +
 fuse4fs/fuse4fs.c    |  231 ++++++++++++++++++++++++++++----------
 misc/fuse2fs.1.in    |    6 +
 misc/fuse2fs.c       |  304 ++++++++++++++++++++++++++++++++++++++------------
 4 files changed, 413 insertions(+), 134 deletions(-)

[PATCHSET RFC v5 7/9] fuse2fs: cache iomap mappings for even better file IO performance

[Darrick J. Wong]

Hi all,

This series improves the performance (and correctness for some
filesystems) by adding the ability to cache iomap mappings in the
kernel.  For filesystems that can change mapping states during pagecache
writeback (e.g. unwritten extent conversion) this is absolutely
necessary to deal with races with writes to the pagecache because
writeback does not take i_rwsem.  For everyone else, it simply
eliminates roundtrips to userspace.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=fuse2fs-iomap-cache
---
Commits in this patchset:
 * fuse2fs: enable caching of iomaps
 * fuse2fs: be smarter about caching iomaps
 * fuse2fs: enable iomap
---
 fuse4fs/fuse4fs.c |   54 +++++++++++++++++++++++++++++++++++++++++++++++++----
 misc/fuse2fs.c    |   50 +++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 96 insertions(+), 8 deletions(-)

[PATCHSET RFC v5 8/9] fuse2fs: improve block and inode caching

[Darrick J. Wong]

Hi all,

This series ports the libext2fs inode cache to the new cache.c hashtable
code that was added for fuse4fs unlinked file support and improves on
the UNIX I/O manager's block cache by adding a new I/O manager that does
its own caching.  Now we no longer have statically sized buffer caching
for the two fuse servers.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=fuse2fs-caching
---
Commits in this patchset:
 * libsupport: add caching IO manager
 * iocache: add the actual buffer cache
 * iocache: bump buffer mru priority every 50 accesses
 * fuse2fs: enable caching IO manager
 * fuse2fs: increase inode cache size
 * libext2fs: improve caching for inodes
---
 lib/ext2fs/ext2fsP.h    |   13 +
 lib/support/cache.h     |    1 
 lib/support/iocache.h   |   17 +
 debugfs/Makefile.in     |    4 
 e2fsck/Makefile.in      |    4 
 fuse4fs/Makefile.in     |    3 
 fuse4fs/fuse4fs.1.in    |    6 
 fuse4fs/fuse4fs.c       |   75 +----
 lib/ext2fs/Makefile.in  |    4 
 lib/ext2fs/inode.c      |  215 +++++++++++---
 lib/ext2fs/io_manager.c |    3 
 lib/support/Makefile.in |    6 
 lib/support/cache.c     |   16 +
 lib/support/iocache.c   |  740 +++++++++++++++++++++++++++++++++++++++++++++++
 misc/Makefile.in        |    4 
 misc/fuse2fs.1.in       |    6 
 misc/fuse2fs.c          |   77 +----
 resize/Makefile.in      |    4 
 tests/progs/Makefile.in |    4 
 19 files changed, 992 insertions(+), 210 deletions(-)
 create mode 100644 lib/support/iocache.h
 create mode 100644 lib/support/iocache.c

[PATCHSET RFC v5 9/9] fuse4fs: run servers as a contained service

[Darrick J. Wong]

Hi all,

In this final series of the fuse-iomap prototype, we package the newly
created fuse4fs server into a systemd socket service.  This service can
be used by the "mount.service" helper in libfuse to implement untrusted
unprivileged mounts.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=fuse4fs-service-container
---
Commits in this patchset:
 * libext2fs: fix MMP code to work with unixfd IO manager
 * fuse4fs: enable safe service mode
 * fuse4fs: set proc title when in fuse service mode
 * fuse4fs: set iomap backing device blocksize
---
 MCONFIG.in                  |    1 
 configure                   |  181 +++++++++++++++++++++++++
 configure.ac                |   69 +++++++++
 debian/fuse4fs.install      |    2 
 fuse4fs/Makefile.in         |   42 +++++-
 fuse4fs/fuse4fs.c           |  315 +++++++++++++++++++++++++++++++++++++++++--
 fuse4fs/fuse4fs.socket.in   |   14 ++
 fuse4fs/fuse4fs@.service.in |   95 +++++++++++++
 lib/config.h.in             |    6 +
 lib/ext2fs/mmp.c            |   46 ++++++
 util/subst.conf.in          |    2 
 11 files changed, 750 insertions(+), 23 deletions(-)
 create mode 100644 fuse4fs/fuse4fs.socket.in
 create mode 100644 fuse4fs/fuse4fs@.service.in

[PATCH 1/8] fuse: fix livelock in synchronous file put from fuseblk workers

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

I observed a hang when running generic/323 against a fuseblk server.
This test opens a file, initiates a lot of AIO writes to that file
descriptor, and closes the file descriptor before the writes complete.
Unsurprisingly, the AIO exerciser threads are mostly stuck waiting for
responses from the fuseblk server:

# cat /proc/372265/task/372313/stack
[<0>] request_wait_answer+0x1fe/0x2a0 [fuse]
[<0>] __fuse_simple_request+0xd3/0x2b0 [fuse]
[<0>] fuse_do_getattr+0xfc/0x1f0 [fuse]
[<0>] fuse_file_read_iter+0xbe/0x1c0 [fuse]
[<0>] aio_read+0x130/0x1e0
[<0>] io_submit_one+0x542/0x860
[<0>] __x64_sys_io_submit+0x98/0x1a0
[<0>] do_syscall_64+0x37/0xf0
[<0>] entry_SYSCALL_64_after_hwframe+0x4b/0x53

But the /weird/ part is that the fuseblk server threads are waiting for
responses from itself:

# cat /proc/372210/task/372232/stack
[<0>] request_wait_answer+0x1fe/0x2a0 [fuse]
[<0>] __fuse_simple_request+0xd3/0x2b0 [fuse]
[<0>] fuse_file_put+0x9a/0xd0 [fuse]
[<0>] fuse_release+0x36/0x50 [fuse]
[<0>] __fput+0xec/0x2b0
[<0>] task_work_run+0x55/0x90
[<0>] syscall_exit_to_user_mode+0xe9/0x100
[<0>] do_syscall_64+0x43/0xf0
[<0>] entry_SYSCALL_64_after_hwframe+0x4b/0x53

The fuseblk server is fuse2fs so there's nothing all that exciting in
the server itself.  So why is the fuse server calling fuse_file_put?
The commit message for the fstest sheds some light on that:

"By closing the file descriptor before calling io_destroy, you pretty
much guarantee that the last put on the ioctx will be done in interrupt
context (during I/O completion).

Aha.  AIO fgets a new struct file from the fd when it queues the ioctx.
The completion of the FUSE_WRITE command from userspace causes the fuse
server to call the AIO completion function.  The completion puts the
struct file, queuing a delayed fput to the fuse server task.  When the
fuse server task returns to userspace, it has to run the delayed fput,
which in the case of a fuseblk server, it does synchronously.

Sending the FUSE_RELEASE command sychronously from fuse server threads
is a bad idea because a client program can initiate enough simultaneous
AIOs such that all the fuse server threads end up in delayed_fput, and
now there aren't any threads left to handle the queued fuse commands.

Fix this by only using asynchronous fputs when closing files, and leave
a comment explaining why.

Cc: <stable@vger.kernel.org> # v2.6.38
Fixes: 5a18ec176c934c ("fuse: fix hang of single threaded fuseblk filesystem")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/file.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 4adcf09d4b01a6..ebdca39b2261d7 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -356,8 +356,14 @@ void fuse_file_release(struct inode *inode, struct fuse_file *ff,
 	 * Make the release synchronous if this is a fuseblk mount,
 	 * synchronous RELEASE is allowed (and desirable) in this case
 	 * because the server can be trusted not to screw up.
+	 *
+	 * Always use the asynchronous file put because the current thread
+	 * might be the fuse server.  This can happen if a process starts some
+	 * aio and closes the fd before the aio completes.  Since aio takes its
+	 * own ref to the file, the IO completion has to drop the ref, which is
+	 * how the fuse server can end up closing its clients' files.
 	 */
-	fuse_file_put(ff, ff->fm->fc->destroy);
+	fuse_file_put(ff, false);
 }
 
 void fuse_release_common(struct file *file, bool isdir)

[PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

generic/488 fails with fuse2fs in the following fashion:

generic/488       _check_generic_filesystem: filesystem on /dev/sdf is inconsistent
(see /var/tmp/fstests/generic/488.full for details)

This test opens a large number of files, unlinks them (which really just
renames them to fuse hidden files), closes the program, unmounts the
filesystem, and runs fsck to check that there aren't any inconsistencies
in the filesystem.

Unfortunately, the 488.full file shows that there are a lot of hidden
files left over in the filesystem, with incorrect link counts.  Tracing
fuse_request_* shows that there are a large number of FUSE_RELEASE
commands that are queued up on behalf of the unlinked files at the time
that fuse_conn_destroy calls fuse_abort_conn.  Had the connection not
aborted, the fuse server would have responded to the RELEASE commands by
removing the hidden files; instead they stick around.

For upper-level fuse servers that don't use fuseblk mode this isn't a
problem because libfuse responds to the connection going down by pruning
its inode cache and calling the fuse server's ->release for any open
files before calling the server's ->destroy function.

For fuseblk servers this is a problem, however, because the kernel sends
FUSE_DESTROY to the fuse server, and the fuse server has to close the
block device before returning.  This means that the kernel must flush
all pending FUSE_RELEASE requests before issuing FUSE_DESTROY.

Create a function to push all the background requests to the queue and
then wait for the number of pending events to hit zero, and call this
before sending FUSE_DESTROY.  That way, all the pending events are
processed by the fuse server and we don't end up with a corrupt
filesystem.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h |    5 +++++
 fs/fuse/dev.c    |   33 +++++++++++++++++++++++++++++++++
 fs/fuse/inode.c  |   11 ++++++++++-
 3 files changed, 48 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index cc428d04be3e14..8edca9ad13a9d1 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1263,6 +1263,11 @@ void fuse_request_end(struct fuse_req *req);
 void fuse_abort_conn(struct fuse_conn *fc);
 void fuse_wait_aborted(struct fuse_conn *fc);
 
+/**
+ * Flush all pending requests and wait for them.
+ */
+void fuse_flush_requests_and_wait(struct fuse_conn *fc);
+
 /* Check if any requests timed out */
 void fuse_check_timeout(struct work_struct *work);
 
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5150aa25e64be9..dcd338b65b2fc7 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -24,6 +24,7 @@
 #include <linux/splice.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
+#include <linux/nmi.h>
 
 #define CREATE_TRACE_POINTS
 #include "fuse_trace.h"
@@ -2385,6 +2386,38 @@ static void end_polls(struct fuse_conn *fc)
 	}
 }
 
+/*
+ * Flush all pending requests and wait for them.  Only call this function when
+ * it is no longer possible for other threads to add requests.
+ */
+void fuse_flush_requests_and_wait(struct fuse_conn *fc)
+{
+	spin_lock(&fc->lock);
+	if (!fc->connected) {
+		spin_unlock(&fc->lock);
+		return;
+	}
+
+	/* Push all the background requests to the queue. */
+	spin_lock(&fc->bg_lock);
+	fc->blocked = 0;
+	fc->max_background = UINT_MAX;
+	flush_bg_queue(fc);
+	spin_unlock(&fc->bg_lock);
+	spin_unlock(&fc->lock);
+
+	/*
+	 * Wait for all the events to complete or abort.  Touch the watchdog
+	 * once per second so that we don't trip the hangcheck timer while
+	 * waiting for the fuse server.
+	 */
+	smp_mb();
+	while (wait_event_timeout(fc->blocked_waitq,
+			!fc->connected || atomic_read(&fc->num_waiting) == 0,
+			HZ) == 0)
+		touch_softlockup_watchdog();
+}
+
 /*
  * Abort all requests.
  *
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 7ddfd2b3cc9c4f..c94aba627a6f11 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -2056,8 +2056,17 @@ void fuse_conn_destroy(struct fuse_mount *fm)
 {
 	struct fuse_conn *fc = fm->fc;
 
-	if (fc->destroy)
+	if (fc->destroy) {
+		/*
+		 * Flush all pending requests (most of which will be
+		 * FUSE_RELEASE) before sending FUSE_DESTROY, because the fuse
+		 * server must close the filesystem before replying to the
+		 * destroy message, because unmount is about to release its
+		 * O_EXCL hold on the block device.
+		 */
+		fuse_flush_requests_and_wait(fc);
 		fuse_send_destroy(fm);
+	}
 
 	fuse_abort_conn(fc);
 	fuse_wait_aborted(fc);

[PATCH 3/8] fuse: capture the unique id of fuse commands being sent

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

The fuse_request_{send,end} tracepoints capture the value of
req->in.h.unique in the trace output.  It would be really nice if we
could use this to match a request to its response for debugging and
latency analysis, but the call to trace_fuse_request_send occurs before
the unique id has been set:

fuse_request_send:    connection 8388608 req 0 opcode 1 (FUSE_LOOKUP) len 107
fuse_request_end:     connection 8388608 req 6 len 16 error -2

(Notice that req moves from 0 to 6)

Move the callsites to trace_fuse_request_send to after the unique id has
been set by introducing a helper to do that for standard fuse_req
requests.  FUSE_FORGET requests are not covered by this because they
appear to be synthesized into the event stream without a fuse_req
object and are never replied to.

Requests that are aborted without ever having been submitted to the fuse
server retain the behavior that only the fuse_request_end tracepoint
shows up in the trace record, and with req==0.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h    |    5 +++++
 fs/fuse/dev.c       |   27 +++++++++++++++++++++++----
 fs/fuse/dev_uring.c |    4 ++--
 fs/fuse/virtio_fs.c |    3 +--
 4 files changed, 31 insertions(+), 8 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 8edca9ad13a9d1..e93a3c3f11d901 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1254,6 +1254,11 @@ static inline ssize_t fuse_simple_idmap_request(struct mnt_idmap *idmap,
 int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
 			   gfp_t gfp_flags);
 
+/**
+ * Assign a unique id to a fuse request
+ */
+void fuse_request_assign_unique(struct fuse_iqueue *fiq, struct fuse_req *req);
+
 /**
  * End a finished request
  */
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index dcd338b65b2fc7..f06208e4364642 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -370,12 +370,32 @@ void fuse_dev_queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
 	}
 }
 
+static inline void fuse_request_assign_unique_locked(struct fuse_iqueue *fiq,
+						     struct fuse_req *req)
+{
+	if (req->in.h.opcode != FUSE_NOTIFY_REPLY)
+		req->in.h.unique = fuse_get_unique_locked(fiq);
+
+	/* tracepoint captures in.h.unique and in.h.len */
+	trace_fuse_request_send(req);
+}
+
+inline void fuse_request_assign_unique(struct fuse_iqueue *fiq,
+				       struct fuse_req *req)
+{
+	if (req->in.h.opcode != FUSE_NOTIFY_REPLY)
+		req->in.h.unique = fuse_get_unique(fiq);
+
+	/* tracepoint captures in.h.unique and in.h.len */
+	trace_fuse_request_send(req);
+}
+EXPORT_SYMBOL_GPL(fuse_request_assign_unique);
+
 static void fuse_dev_queue_req(struct fuse_iqueue *fiq, struct fuse_req *req)
 {
 	spin_lock(&fiq->lock);
 	if (fiq->connected) {
-		if (req->in.h.opcode != FUSE_NOTIFY_REPLY)
-			req->in.h.unique = fuse_get_unique_locked(fiq);
+		fuse_request_assign_unique_locked(fiq, req);
 		list_add_tail(&req->list, &fiq->pending);
 		fuse_dev_wake_and_unlock(fiq);
 	} else {
@@ -398,7 +418,6 @@ static void fuse_send_one(struct fuse_iqueue *fiq, struct fuse_req *req)
 	req->in.h.len = sizeof(struct fuse_in_header) +
 		fuse_len_args(req->args->in_numargs,
 			      (struct fuse_arg *) req->args->in_args);
-	trace_fuse_request_send(req);
 	fiq->ops->send_req(fiq, req);
 }
 
@@ -688,10 +707,10 @@ static bool fuse_request_queue_background_uring(struct fuse_conn *fc,
 {
 	struct fuse_iqueue *fiq = &fc->iq;
 
-	req->in.h.unique = fuse_get_unique(fiq);
 	req->in.h.len = sizeof(struct fuse_in_header) +
 		fuse_len_args(req->args->in_numargs,
 			      (struct fuse_arg *) req->args->in_args);
+	fuse_request_assign_unique(fiq, req);
 
 	return fuse_uring_queue_bq_req(req);
 }
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index 249b210becb1cc..7b541aeea1813f 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -7,6 +7,7 @@
 #include "fuse_i.h"
 #include "dev_uring_i.h"
 #include "fuse_dev_i.h"
+#include "fuse_trace.h"
 
 #include <linux/fs.h>
 #include <linux/io_uring/cmd.h>
@@ -1268,8 +1269,7 @@ void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req)
 	if (!queue)
 		goto err;
 
-	if (req->in.h.opcode != FUSE_NOTIFY_REPLY)
-		req->in.h.unique = fuse_get_unique(fiq);
+	fuse_request_assign_unique(fiq, req);
 
 	spin_lock(&queue->lock);
 	err = -ENOTCONN;
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 76c8fd0bfc75d5..a880294549a6bd 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -1480,8 +1480,7 @@ static void virtio_fs_send_req(struct fuse_iqueue *fiq, struct fuse_req *req)
 	struct virtio_fs_vq *fsvq;
 	int ret;
 
-	if (req->in.h.opcode != FUSE_NOTIFY_REPLY)
-		req->in.h.unique = fuse_get_unique(fiq);
+	fuse_request_assign_unique(fiq, req);
 
 	clear_bit(FR_PENDING, &req->flags);
 

[PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create a new fuse context flag that indicates that the kernel should
implement various local filesystem behaviors instead of passing vfs
commands straight through to the fuse server and expecting the server to
do all the work.  For example, this means that we'll use the kernel to
transform some ACL updates into mode changes, and later to do
enforcement of the immutable and append iflags.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h |    4 ++++
 fs/fuse/inode.c  |    2 ++
 2 files changed, 6 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index e93a3c3f11d901..e13e8270f4f58d 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -603,6 +603,7 @@ struct fuse_fs_context {
 	bool no_control:1;
 	bool no_force_umount:1;
 	bool legacy_opts_show:1;
+	bool local_fs:1;
 	enum fuse_dax_mode dax_mode;
 	unsigned int max_read;
 	unsigned int blksize;
@@ -901,6 +902,9 @@ struct fuse_conn {
 	/* Is link not implemented by fs? */
 	unsigned int no_link:1;
 
+	/* Should this filesystem behave like a local filesystem? */
+	unsigned int local_fs:1;
+
 	/* Use io_uring for communication */
 	unsigned int io_uring;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index c94aba627a6f11..c8dd0bcb7e6f9f 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1862,6 +1862,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 	fc->destroy = ctx->destroy;
 	fc->no_control = ctx->no_control;
 	fc->no_force_umount = ctx->no_force_umount;
+	fc->local_fs = ctx->local_fs;
 
 	err = -ENOMEM;
 	root = fuse_get_root_inode(sb, ctx->rootmode);
@@ -2029,6 +2030,7 @@ static int fuse_init_fs_context(struct fs_context *fsc)
 	if (fsc->fs_type == &fuseblk_fs_type) {
 		ctx->is_bdev = true;
 		ctx->destroy = true;
+		ctx->local_fs = true;
 	}
 #endif
 

[PATCH 5/8] fuse: implement file attributes mask for statx

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Actually copy the attributes/attributes_mask from userspace.  Ignore
file attributes bits that the VFS sets (or doesn't set) on its own.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
---
 fs/fuse/fuse_i.h |   37 +++++++++++++++++++++++++++++++++++++
 fs/fuse/dir.c    |    4 ++++
 fs/fuse/inode.c  |    3 +++
 3 files changed, 44 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index e13e8270f4f58d..52776b77efc0e4 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -140,6 +140,10 @@ struct fuse_inode {
 	/** Version of last attribute change */
 	u64 attr_version;
 
+	/** statx file attributes */
+	u64 statx_attributes;
+	u64 statx_attributes_mask;
+
 	union {
 		/* read/write io cache (regular file only) */
 		struct {
@@ -1221,6 +1225,39 @@ void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 				   u64 attr_valid, u32 cache_mask,
 				   u64 evict_ctr);
 
+/*
+ * These statx attribute flags are set by the VFS so mask them out of replies
+ * from the fuse server for local filesystems.  Nonlocal filesystems are
+ * responsible for enforcing and advertising these flags themselves.
+ */
+#define FUSE_STATX_LOCAL_VFS_ATTRIBUTES (STATX_ATTR_IMMUTABLE | \
+					 STATX_ATTR_APPEND)
+
+/*
+ * These statx attribute flags are set by the VFS so mask them out of replies
+ * from the fuse server.
+ */
+#define FUSE_STATX_VFS_ATTRIBUTES (STATX_ATTR_AUTOMOUNT | STATX_ATTR_DAX | \
+				   STATX_ATTR_MOUNT_ROOT)
+
+static inline u64 fuse_statx_attributes_mask(const struct fuse_conn *fc,
+					     const struct fuse_statx *sx)
+{
+	if (fc->local_fs)
+		return sx->attributes_mask & ~(FUSE_STATX_VFS_ATTRIBUTES |
+					       FUSE_STATX_LOCAL_VFS_ATTRIBUTES);
+	return sx->attributes_mask & ~FUSE_STATX_VFS_ATTRIBUTES;
+}
+
+static inline u64 fuse_statx_attributes(const struct fuse_conn *fc,
+					const struct fuse_statx *sx)
+{
+	if (fc->local_fs)
+		return sx->attributes & ~(FUSE_STATX_VFS_ATTRIBUTES |
+					  FUSE_STATX_LOCAL_VFS_ATTRIBUTES);
+	return sx->attributes & ~FUSE_STATX_VFS_ATTRIBUTES;
+}
+
 u32 fuse_get_cache_mask(struct inode *inode);
 
 /**
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 5c569c3cb53f3d..a7f47e43692f1c 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1278,6 +1278,8 @@ static int fuse_do_statx(struct mnt_idmap *idmap, struct inode *inode,
 		stat->result_mask = sx->mask & (STATX_BASIC_STATS | STATX_BTIME);
 		stat->btime.tv_sec = sx->btime.tv_sec;
 		stat->btime.tv_nsec = min_t(u32, sx->btime.tv_nsec, NSEC_PER_SEC - 1);
+		stat->attributes |= fuse_statx_attributes(fm->fc, sx);
+		stat->attributes_mask |= fuse_statx_attributes_mask(fm->fc, sx);
 		fuse_fillattr(idmap, inode, &attr, stat);
 		stat->result_mask |= STATX_TYPE;
 	}
@@ -1382,6 +1384,8 @@ static int fuse_update_get_attr(struct mnt_idmap *idmap, struct inode *inode,
 			stat->btime = fi->i_btime;
 			stat->result_mask |= STATX_BTIME;
 		}
+		stat->attributes = fi->statx_attributes;
+		stat->attributes_mask = fi->statx_attributes_mask;
 	}
 
 	return err;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index c8dd0bcb7e6f9f..55db991bb6b8c1 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -287,6 +287,9 @@ void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 			fi->i_btime.tv_sec = sx->btime.tv_sec;
 			fi->i_btime.tv_nsec = sx->btime.tv_nsec;
 		}
+
+		fi->statx_attributes = fuse_statx_attributes(fc, sx);
+		fi->statx_attributes_mask = fuse_statx_attributes_mask(fc, sx);
 	}
 
 	if (attr->blksize)

[PATCH 6/8] fuse: update file mode when updating acls

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

If someone sets ACLs on a file that can be expressed fully as Unix DAC
mode bits, most local filesystems will then update the mode bits and
drop the ACL xattr to reduce inefficiency in the file access paths.
Let's do that too.  Note that means that we can setacl and end up with
no ACL xattrs, so we also need to tolerate ENODATA returns from
fuse_removexattr.

Note that here we define a "local" fuse filesystem as one that uses
fuseblk mode; we'll shortly add fuse servers that use iomap for the file
IO path to that list.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/acl.c |   40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 8f484b105f13ab..4997827ee83c6d 100644
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -11,6 +11,16 @@
 #include <linux/posix_acl.h>
 #include <linux/posix_acl_xattr.h>
 
+/*
+ * If this fuse server behaves like a local filesystem, we can implement the
+ * kernel's optimizations for ACLs for local filesystems instead of passing
+ * the ACL requests straight through to another server.
+ */
+static inline bool fuse_has_local_acls(const struct fuse_conn *fc)
+{
+	return fc->posix_acl && fc->local_fs;
+}
+
 static struct posix_acl *__fuse_get_acl(struct fuse_conn *fc,
 					struct inode *inode, int type, bool rcu)
 {
@@ -98,6 +108,7 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 	struct inode *inode = d_inode(dentry);
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	const char *name;
+	umode_t mode = inode->i_mode;
 	int ret;
 
 	if (fuse_is_bad(inode))
@@ -113,6 +124,17 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 	else
 		return -EINVAL;
 
+	/*
+	 * If the ACL can be represented entirely with changes to the mode
+	 * bits, then most filesystems will update the mode bits and delete
+	 * the ACL xattr.
+	 */
+	if (acl && type == ACL_TYPE_ACCESS && fuse_has_local_acls(fc)) {
+		ret = posix_acl_update_mode(idmap, inode, &mode, &acl);
+		if (ret)
+			return ret;
+	}
+
 	if (acl) {
 		unsigned int extra_flags = 0;
 		/*
@@ -143,7 +165,7 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		 * through POSIX ACLs. Such daemons don't expect setgid bits to
 		 * be stripped.
 		 */
-		if (fc->posix_acl &&
+		if (fc->posix_acl && mode == inode->i_mode &&
 		    !in_group_or_capable(idmap, inode,
 					 i_gid_into_vfsgid(idmap, inode)))
 			extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID;
@@ -152,6 +174,22 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		kfree(value);
 	} else {
 		ret = fuse_removexattr(inode, name);
+		/* If the acl didn't exist to start with that's fine. */
+		if (ret == -ENODATA)
+			ret = 0;
+	}
+
+	/* If we scheduled a mode update above, push that to userspace now. */
+	if (!ret) {
+		struct iattr attr = { };
+
+		if (mode != inode->i_mode) {
+			attr.ia_valid |= ATTR_MODE;
+			attr.ia_mode = mode;
+		}
+
+		if (attr.ia_valid)
+			ret = fuse_do_setattr(idmap, dentry, &attr, NULL);
 	}
 
 	if (fc->posix_acl) {

[PATCH 7/8] fuse: propagate default and file acls on creation

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

For local filesystems, propagate the default and file access ACLs to new
children when creating them, just like the other in-kernel local
filesystems.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h |    4 ++
 fs/fuse/acl.c    |   65 ++++++++++++++++++++++++++++++++++++++
 fs/fuse/dir.c    |   92 +++++++++++++++++++++++++++++++++++++++++-------------
 3 files changed, 138 insertions(+), 23 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 52776b77efc0e4..b9306678dcda0d 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1507,6 +1507,10 @@ struct posix_acl *fuse_get_acl(struct mnt_idmap *idmap,
 			       struct dentry *dentry, int type);
 int fuse_set_acl(struct mnt_idmap *, struct dentry *dentry,
 		 struct posix_acl *acl, int type);
+int fuse_acl_create(struct inode *dir, umode_t *mode,
+		    struct posix_acl **default_acl, struct posix_acl **acl);
+int fuse_init_acls(struct inode *inode, const struct posix_acl *default_acl,
+		   const struct posix_acl *acl);
 
 /* readdir.c */
 int fuse_readdir(struct file *file, struct dir_context *ctx);
diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 4997827ee83c6d..4faee72f1365a5 100644
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -203,3 +203,68 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 
 	return ret;
 }
+
+int fuse_acl_create(struct inode *dir, umode_t *mode,
+		    struct posix_acl **default_acl, struct posix_acl **acl)
+{
+	struct fuse_conn *fc = get_fuse_conn(dir);
+
+	if (fuse_is_bad(dir))
+		return -EIO;
+
+	if (IS_POSIXACL(dir) && fuse_has_local_acls(fc))
+		return posix_acl_create(dir, mode, default_acl, acl);
+
+	if (!fc->dont_mask)
+		*mode &= ~current_umask();
+
+	*default_acl = NULL;
+	*acl = NULL;
+	return 0;
+}
+
+static int __fuse_set_acl(struct inode *inode, const char *name,
+			  const struct posix_acl *acl)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	size_t size = posix_acl_xattr_size(acl->a_count);
+	void *value;
+	int ret;
+
+	if (size > PAGE_SIZE)
+		return -E2BIG;
+
+	value = kmalloc(size, GFP_KERNEL);
+	if (!value)
+		return -ENOMEM;
+
+	ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);
+	if (ret < 0)
+		goto out_value;
+
+	ret = fuse_setxattr(inode, name, value, size, 0, 0);
+out_value:
+	kfree(value);
+	return ret;
+}
+
+int fuse_init_acls(struct inode *inode, const struct posix_acl *default_acl,
+		   const struct posix_acl *acl)
+{
+	int ret;
+
+	if (default_acl) {
+		ret = __fuse_set_acl(inode, XATTR_NAME_POSIX_ACL_DEFAULT,
+				     default_acl);
+		if (ret)
+			return ret;
+	}
+
+	if (acl) {
+		ret = __fuse_set_acl(inode, XATTR_NAME_POSIX_ACL_ACCESS, acl);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index a7f47e43692f1c..b116e42431ee12 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -628,26 +628,28 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
 	struct fuse_entry_out outentry;
 	struct fuse_inode *fi;
 	struct fuse_file *ff;
+	struct posix_acl *default_acl = NULL, *acl = NULL;
 	int epoch, err;
 	bool trunc = flags & O_TRUNC;
 
 	/* Userspace expects S_IFREG in create mode */
 	BUG_ON((mode & S_IFMT) != S_IFREG);
 
+	err = fuse_acl_create(dir, &mode, &default_acl, &acl);
+	if (err)
+		return err;
+
 	epoch = atomic_read(&fm->fc->epoch);
 	forget = fuse_alloc_forget();
 	err = -ENOMEM;
 	if (!forget)
-		goto out_err;
+		goto out_acl_release;
 
 	err = -ENOMEM;
 	ff = fuse_file_alloc(fm, true);
 	if (!ff)
 		goto out_put_forget_req;
 
-	if (!fm->fc->dont_mask)
-		mode &= ~current_umask();
-
 	flags &= ~O_NOCTTY;
 	memset(&inarg, 0, sizeof(inarg));
 	memset(&outentry, 0, sizeof(outentry));
@@ -699,12 +701,16 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
 		fuse_sync_release(NULL, ff, flags);
 		fuse_queue_forget(fm->fc, forget, outentry.nodeid, 1);
 		err = -ENOMEM;
-		goto out_err;
+		goto out_acl_release;
 	}
 	kfree(forget);
 	d_instantiate(entry, inode);
 	entry->d_time = epoch;
 	fuse_change_entry_timeout(entry, &outentry);
+
+	err = fuse_init_acls(inode, default_acl, acl);
+	if (err)
+		goto out_acl_release;
 	fuse_dir_changed(dir);
 	err = generic_file_open(inode, file);
 	if (!err) {
@@ -726,7 +732,9 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
 	fuse_file_free(ff);
 out_put_forget_req:
 	kfree(forget);
-out_err:
+out_acl_release:
+	posix_acl_release(default_acl);
+	posix_acl_release(acl);
 	return err;
 }
 
@@ -785,7 +793,9 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
  */
 static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm,
 				       struct fuse_args *args, struct inode *dir,
-				       struct dentry *entry, umode_t mode)
+				       struct dentry *entry, umode_t mode,
+				       struct posix_acl *default_acl,
+				       struct posix_acl *acl)
 {
 	struct fuse_entry_out outarg;
 	struct inode *inode;
@@ -793,14 +803,18 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
 	struct fuse_forget_link *forget;
 	int epoch, err;
 
-	if (fuse_is_bad(dir))
-		return ERR_PTR(-EIO);
+	if (fuse_is_bad(dir)) {
+		err = -EIO;
+		goto out_acl_release;
+	}
 
 	epoch = atomic_read(&fm->fc->epoch);
 
 	forget = fuse_alloc_forget();
-	if (!forget)
-		return ERR_PTR(-ENOMEM);
+	if (!forget) {
+		err = -ENOMEM;
+		goto out_acl_release;
+	}
 
 	memset(&outarg, 0, sizeof(outarg));
 	args->nodeid = get_node_id(dir);
@@ -830,7 +844,8 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
 			  &outarg.attr, ATTR_TIMEOUT(&outarg), 0, 0);
 	if (!inode) {
 		fuse_queue_forget(fm->fc, forget, outarg.nodeid, 1);
-		return ERR_PTR(-ENOMEM);
+		err = -ENOMEM;
+		goto out_acl_release;
 	}
 	kfree(forget);
 
@@ -846,19 +861,31 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
 		entry->d_time = epoch;
 		fuse_change_entry_timeout(entry, &outarg);
 	}
+
+	err = fuse_init_acls(inode, default_acl, acl);
+	if (err)
+		goto out_acl_release;
 	fuse_dir_changed(dir);
+
+	posix_acl_release(default_acl);
+	posix_acl_release(acl);
 	return d;
 
  out_put_forget_req:
 	if (err == -EEXIST)
 		fuse_invalidate_entry(entry);
 	kfree(forget);
+ out_acl_release:
+	posix_acl_release(default_acl);
+	posix_acl_release(acl);
 	return ERR_PTR(err);
 }
 
 static int create_new_nondir(struct mnt_idmap *idmap, struct fuse_mount *fm,
 			     struct fuse_args *args, struct inode *dir,
-			     struct dentry *entry, umode_t mode)
+			     struct dentry *entry, umode_t mode,
+			     struct posix_acl *default_acl,
+			     struct posix_acl *acl)
 {
 	/*
 	 * Note that when creating anything other than a directory we
@@ -869,7 +896,8 @@ static int create_new_nondir(struct mnt_idmap *idmap, struct fuse_mount *fm,
 	 */
 	WARN_ON_ONCE(S_ISDIR(mode));
 
-	return PTR_ERR(create_new_entry(idmap, fm, args, dir, entry, mode));
+	return PTR_ERR(create_new_entry(idmap, fm, args, dir, entry, mode,
+					default_acl, acl));
 }
 
 static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
@@ -877,10 +905,13 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
 {
 	struct fuse_mknod_in inarg;
 	struct fuse_mount *fm = get_fuse_mount(dir);
+	struct posix_acl *default_acl, *acl;
 	FUSE_ARGS(args);
+	int err;
 
-	if (!fm->fc->dont_mask)
-		mode &= ~current_umask();
+	err = fuse_acl_create(dir, &mode, &default_acl, &acl);
+	if (err)
+		return err;
 
 	memset(&inarg, 0, sizeof(inarg));
 	inarg.mode = mode;
@@ -892,7 +923,8 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
 	args.in_args[0].value = &inarg;
 	args.in_args[1].size = entry->d_name.len + 1;
 	args.in_args[1].value = entry->d_name.name;
-	return create_new_nondir(idmap, fm, &args, dir, entry, mode);
+	return create_new_nondir(idmap, fm, &args, dir, entry, mode,
+				 default_acl, acl);
 }
 
 static int fuse_create(struct mnt_idmap *idmap, struct inode *dir,
@@ -924,13 +956,17 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 {
 	struct fuse_mkdir_in inarg;
 	struct fuse_mount *fm = get_fuse_mount(dir);
+	struct posix_acl *default_acl, *acl;
 	FUSE_ARGS(args);
+	int err;
 
-	if (!fm->fc->dont_mask)
-		mode &= ~current_umask();
+	mode |= S_IFDIR;	/* vfs doesn't set S_IFDIR for us */
+	err = fuse_acl_create(dir, &mode, &default_acl, &acl);
+	if (err)
+		return ERR_PTR(err);
 
 	memset(&inarg, 0, sizeof(inarg));
-	inarg.mode = mode;
+	inarg.mode = mode & ~S_IFDIR;
 	inarg.umask = current_umask();
 	args.opcode = FUSE_MKDIR;
 	args.in_numargs = 2;
@@ -938,7 +974,8 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 	args.in_args[0].value = &inarg;
 	args.in_args[1].size = entry->d_name.len + 1;
 	args.in_args[1].value = entry->d_name.name;
-	return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR);
+	return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR,
+				default_acl, acl);
 }
 
 static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
@@ -946,7 +983,14 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
 {
 	struct fuse_mount *fm = get_fuse_mount(dir);
 	unsigned len = strlen(link) + 1;
+	struct posix_acl *default_acl, *acl;
+	umode_t mode = S_IFLNK | 0777;
 	FUSE_ARGS(args);
+	int err;
+
+	err = fuse_acl_create(dir, &mode, &default_acl, &acl);
+	if (err)
+		return err;
 
 	args.opcode = FUSE_SYMLINK;
 	args.in_numargs = 3;
@@ -955,7 +999,8 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	args.in_args[1].value = entry->d_name.name;
 	args.in_args[2].size = len;
 	args.in_args[2].value = link;
-	return create_new_nondir(idmap, fm, &args, dir, entry, S_IFLNK);
+	return create_new_nondir(idmap, fm, &args, dir, entry, S_IFLNK,
+				 default_acl, acl);
 }
 
 void fuse_flush_time_update(struct inode *inode)
@@ -1155,7 +1200,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir,
 	args.in_args[0].value = &inarg;
 	args.in_args[1].size = newent->d_name.len + 1;
 	args.in_args[1].value = newent->d_name.name;
-	err = create_new_nondir(&invalid_mnt_idmap, fm, &args, newdir, newent, inode->i_mode);
+	err = create_new_nondir(&invalid_mnt_idmap, fm, &args, newdir, newent,
+				inode->i_mode, NULL, NULL);
 	if (!err)
 		fuse_update_ctime_in_cache(inode);
 	else if (err == -EINTR)

[PATCH 8/8] fuse: enable FUSE_SYNCFS for all fuseblk servers

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Turn on syncfs for all fuseblk servers so that the ones in the know can
flush cached intermediate data and logs to disk.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/inode.c |    1 +
 1 file changed, 1 insertion(+)


diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 55db991bb6b8c1..869d8a87bfb628 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1824,6 +1824,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 		    !sb_set_blocksize(sb, PAGE_SIZE))
 			goto err;
 #endif
+		fc->sync_fs = 1;
 	} else {
 		sb->s_blocksize = PAGE_SIZE;
 		sb->s_blocksize_bits = PAGE_SHIFT;

[PATCH 1/2] iomap: trace iomap_zero_iter zeroing activities

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Trace which bytes actually get zeroed.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/iomap/trace.h       |    1 +
 fs/iomap/buffered-io.c |    3 +++
 2 files changed, 4 insertions(+)


diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
index 6ad66e6ba653e8..a61c1dae474270 100644
--- a/fs/iomap/trace.h
+++ b/fs/iomap/trace.h
@@ -84,6 +84,7 @@ DEFINE_RANGE_EVENT(iomap_release_folio);
 DEFINE_RANGE_EVENT(iomap_invalidate_folio);
 DEFINE_RANGE_EVENT(iomap_dio_invalidate_fail);
 DEFINE_RANGE_EVENT(iomap_dio_rw_queued);
+DEFINE_RANGE_EVENT(iomap_zero_iter);
 
 #define IOMAP_TYPE_STRINGS \
 	{ IOMAP_HOLE,		"HOLE" }, \
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 1e95a331a682e2..741f1f6001e1ff 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1415,6 +1415,9 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero,
 		/* warn about zeroing folios beyond eof that won't write back */
 		WARN_ON_ONCE(folio_pos(folio) > iter->inode->i_size);
 
+		trace_iomap_zero_iter(iter->inode, folio_pos(folio) + offset,
+				bytes);
+
 		folio_zero_range(folio, offset, bytes);
 		folio_mark_accessed(folio);
 

[PATCH 2/2] iomap: error out on file IO when there is no inline_data buffer

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Return IO errors if an ->iomap_begin implementation returns an
IOMAP_INLINE buffer but forgets to set the inline_data pointer.
Filesystems should never do this, but we could help fs developers (me)
fix their bugs by handling this more gracefully than crashing the
kernel.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/iomap/buffered-io.c |   15 ++++++++++-----
 fs/iomap/direct-io.c   |    3 +++
 2 files changed, 13 insertions(+), 5 deletions(-)


diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 741f1f6001e1ff..869f178aea28d3 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -312,6 +312,9 @@ static int iomap_read_inline_data(const struct iomap_iter *iter,
 	size_t size = i_size_read(iter->inode) - iomap->offset;
 	size_t offset = offset_in_folio(folio, iomap->offset);
 
+	if (WARN_ON_ONCE(iomap->inline_data == NULL))
+		return -EIO;
+
 	if (folio_test_uptodate(folio))
 		return 0;
 
@@ -913,7 +916,7 @@ static bool __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
 	return true;
 }
 
-static void iomap_write_end_inline(const struct iomap_iter *iter,
+static bool iomap_write_end_inline(const struct iomap_iter *iter,
 		struct folio *folio, loff_t pos, size_t copied)
 {
 	const struct iomap *iomap = &iter->iomap;
@@ -922,12 +925,16 @@ static void iomap_write_end_inline(const struct iomap_iter *iter,
 	WARN_ON_ONCE(!folio_test_uptodate(folio));
 	BUG_ON(!iomap_inline_data_valid(iomap));
 
+	if (WARN_ON_ONCE(iomap->inline_data == NULL))
+		return false;
+
 	flush_dcache_folio(folio);
 	addr = kmap_local_folio(folio, pos);
 	memcpy(iomap_inline_data(iomap, pos), addr, copied);
 	kunmap_local(addr);
 
 	mark_inode_dirty(iter->inode);
+	return true;
 }
 
 /*
@@ -940,10 +947,8 @@ static bool iomap_write_end(struct iomap_iter *iter, size_t len, size_t copied,
 	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 	loff_t pos = iter->pos;
 
-	if (srcmap->type == IOMAP_INLINE) {
-		iomap_write_end_inline(iter, folio, pos, copied);
-		return true;
-	}
+	if (srcmap->type == IOMAP_INLINE)
+		return iomap_write_end_inline(iter, folio, pos, copied);
 
 	if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
 		size_t bh_written;
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 6dc4e18f93a40a..a992130a1cb6dd 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -523,6 +523,9 @@ static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio)
 	loff_t pos = iomi->pos;
 	u64 copied;
 
+	if (WARN_ON_ONCE(inline_data == NULL))
+		return -EIO;
+
 	if (WARN_ON_ONCE(!iomap_inline_data_valid(iomap)))
 		return -EIO;
 

[PATCH 1/5] fuse: allow synchronous FUSE_INIT

[Darrick J. Wong]

From: Miklos Szeredi <mszeredi@redhat.com>

FUSE_INIT has always been asynchronous with mount.  That means that the
server processed this request after the mount syscall returned.

This means that FUSE_INIT can't supply the root inode's ID, hence it
currently has a hardcoded value.  There are other limitations such as not
being able to perform getxattr during mount, which is needed by selinux.

To remove these limitations allow server to process FUSE_INIT while
initializing the in-core super block for the fuse filesystem.  This can
only be done if the server is prepared to handle this, so add
FUSE_DEV_IOC_SYNC_INIT ioctl, which

 a) lets the server know whether this feature is supported, returning
 ENOTTY othewrwise.

 b) lets the kernel know to perform a synchronous initialization

The implementation is slightly tricky, since fuse_dev/fuse_conn are set up
only during super block creation.  This is solved by setting the private
data of the fuse device file to a special value ((struct fuse_dev *) 1) and
waiting for this to be turned into a proper fuse_dev before commecing with
operations on the device file.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_dev_i.h      |   13 +++++++-
 fs/fuse/fuse_i.h          |    5 ++-
 include/uapi/linux/fuse.h |    1 +
 fs/fuse/cuse.c            |    3 +-
 fs/fuse/dev.c             |   74 +++++++++++++++++++++++++++++++++------------
 fs/fuse/dev_uring.c       |    4 +-
 fs/fuse/inode.c           |   50 ++++++++++++++++++++++++------
 7 files changed, 115 insertions(+), 35 deletions(-)


diff --git a/fs/fuse/fuse_dev_i.h b/fs/fuse/fuse_dev_i.h
index 5a9bd771a3193d..6e8373f970409e 100644
--- a/fs/fuse/fuse_dev_i.h
+++ b/fs/fuse/fuse_dev_i.h
@@ -12,6 +12,8 @@
 #define FUSE_INT_REQ_BIT (1ULL << 0)
 #define FUSE_REQ_ID_STEP (1ULL << 1)
 
+extern struct wait_queue_head fuse_dev_waitq;
+
 struct fuse_arg;
 struct fuse_args;
 struct fuse_pqueue;
@@ -37,15 +39,22 @@ struct fuse_copy_state {
 	} ring;
 };
 
-static inline struct fuse_dev *fuse_get_dev(struct file *file)
+#define FUSE_DEV_SYNC_INIT ((struct fuse_dev *) 1)
+#define FUSE_DEV_PTR_MASK (~1UL)
+
+static inline struct fuse_dev *__fuse_get_dev(struct file *file)
 {
 	/*
 	 * Lockless access is OK, because file->private data is set
 	 * once during mount and is valid until the file is released.
 	 */
-	return READ_ONCE(file->private_data);
+	struct fuse_dev *fud = READ_ONCE(file->private_data);
+
+	return (typeof(fud)) ((unsigned long) fud & FUSE_DEV_PTR_MASK);
 }
 
+struct fuse_dev *fuse_get_dev(struct file *file);
+
 unsigned int fuse_req_hash(u64 unique);
 struct fuse_req *fuse_request_find(struct fuse_pqueue *fpq, u64 unique);
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index b9306678dcda0d..02f0138e2fe443 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -909,6 +909,9 @@ struct fuse_conn {
 	/* Should this filesystem behave like a local filesystem? */
 	unsigned int local_fs:1;
 
+	/* Is synchronous FUSE_INIT allowed? */
+	unsigned int sync_init:1;
+
 	/* Use io_uring for communication */
 	unsigned int io_uring;
 
@@ -1366,7 +1369,7 @@ struct fuse_dev *fuse_dev_alloc_install(struct fuse_conn *fc);
 struct fuse_dev *fuse_dev_alloc(void);
 void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc);
 void fuse_dev_free(struct fuse_dev *fud);
-void fuse_send_init(struct fuse_mount *fm);
+int fuse_send_init(struct fuse_mount *fm);
 
 /**
  * Fill in superblock and initialize fuse connection
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 122d6586e8d4da..1d76d0332f46f6 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1126,6 +1126,7 @@ struct fuse_backing_map {
 #define FUSE_DEV_IOC_BACKING_OPEN	_IOW(FUSE_DEV_IOC_MAGIC, 1, \
 					     struct fuse_backing_map)
 #define FUSE_DEV_IOC_BACKING_CLOSE	_IOW(FUSE_DEV_IOC_MAGIC, 2, uint32_t)
+#define FUSE_DEV_IOC_SYNC_INIT		_IO(FUSE_DEV_IOC_MAGIC, 3)
 
 struct fuse_lseek_in {
 	uint64_t	fh;
diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index b39844d75a806f..28c96961e85d1c 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -52,6 +52,7 @@
 #include <linux/user_namespace.h>
 
 #include "fuse_i.h"
+#include "fuse_dev_i.h"
 
 #define CUSE_CONNTBL_LEN	64
 
@@ -547,7 +548,7 @@ static int cuse_channel_open(struct inode *inode, struct file *file)
  */
 static int cuse_channel_release(struct inode *inode, struct file *file)
 {
-	struct fuse_dev *fud = file->private_data;
+	struct fuse_dev *fud = __fuse_get_dev(file);
 	struct cuse_conn *cc = fc_to_cc(fud->fc);
 
 	/* remove from the conntbl, no more access from this point on */
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index f06208e4364642..e5aaf0c668bc11 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1548,14 +1548,34 @@ static int fuse_dev_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
+struct fuse_dev *fuse_get_dev(struct file *file)
+{
+	struct fuse_dev *fud = __fuse_get_dev(file);
+	int err;
+
+	if (likely(fud))
+		return fud;
+
+	err = wait_event_interruptible(fuse_dev_waitq,
+				       READ_ONCE(file->private_data) != FUSE_DEV_SYNC_INIT);
+	if (err)
+		return ERR_PTR(err);
+
+	fud = __fuse_get_dev(file);
+	if (!fud)
+		return ERR_PTR(-EPERM);
+
+	return fud;
+}
+
 static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct fuse_copy_state cs;
 	struct file *file = iocb->ki_filp;
 	struct fuse_dev *fud = fuse_get_dev(file);
 
-	if (!fud)
-		return -EPERM;
+	if (IS_ERR(fud))
+		return PTR_ERR(fud);
 
 	if (!user_backed_iter(to))
 		return -EINVAL;
@@ -1575,8 +1595,8 @@ static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
 	struct fuse_copy_state cs;
 	struct fuse_dev *fud = fuse_get_dev(in);
 
-	if (!fud)
-		return -EPERM;
+	if (IS_ERR(fud))
+		return PTR_ERR(fud);
 
 	bufs = kvmalloc_array(pipe->max_usage, sizeof(struct pipe_buffer),
 			      GFP_KERNEL);
@@ -2251,8 +2271,8 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from)
 	struct fuse_copy_state cs;
 	struct fuse_dev *fud = fuse_get_dev(iocb->ki_filp);
 
-	if (!fud)
-		return -EPERM;
+	if (IS_ERR(fud))
+		return PTR_ERR(fud);
 
 	if (!user_backed_iter(from))
 		return -EINVAL;
@@ -2276,8 +2296,8 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
 	ssize_t ret;
 
 	fud = fuse_get_dev(out);
-	if (!fud)
-		return -EPERM;
+	if (IS_ERR(fud))
+		return PTR_ERR(fud);
 
 	pipe_lock(pipe);
 
@@ -2361,7 +2381,7 @@ static __poll_t fuse_dev_poll(struct file *file, poll_table *wait)
 	struct fuse_iqueue *fiq;
 	struct fuse_dev *fud = fuse_get_dev(file);
 
-	if (!fud)
+	if (IS_ERR(fud))
 		return EPOLLERR;
 
 	fiq = &fud->fc->iq;
@@ -2540,7 +2560,7 @@ void fuse_wait_aborted(struct fuse_conn *fc)
 
 int fuse_dev_release(struct inode *inode, struct file *file)
 {
-	struct fuse_dev *fud = fuse_get_dev(file);
+	struct fuse_dev *fud = __fuse_get_dev(file);
 
 	if (fud) {
 		struct fuse_conn *fc = fud->fc;
@@ -2571,8 +2591,8 @@ static int fuse_dev_fasync(int fd, struct file *file, int on)
 {
 	struct fuse_dev *fud = fuse_get_dev(file);
 
-	if (!fud)
-		return -EPERM;
+	if (IS_ERR(fud))
+		return PTR_ERR(fud);
 
 	/* No locking - fasync_helper does its own locking */
 	return fasync_helper(fd, file, on, &fud->fc->iq.fasync);
@@ -2582,7 +2602,7 @@ static int fuse_device_clone(struct fuse_conn *fc, struct file *new)
 {
 	struct fuse_dev *fud;
 
-	if (new->private_data)
+	if (__fuse_get_dev(new))
 		return -EINVAL;
 
 	fud = fuse_dev_alloc_install(fc);
@@ -2613,7 +2633,7 @@ static long fuse_dev_ioctl_clone(struct file *file, __u32 __user *argp)
 	 * uses the same ioctl handler.
 	 */
 	if (fd_file(f)->f_op == file->f_op)
-		fud = fuse_get_dev(fd_file(f));
+		fud = __fuse_get_dev(fd_file(f));
 
 	res = -EINVAL;
 	if (fud) {
@@ -2631,8 +2651,8 @@ static long fuse_dev_ioctl_backing_open(struct file *file,
 	struct fuse_dev *fud = fuse_get_dev(file);
 	struct fuse_backing_map map;
 
-	if (!fud)
-		return -EPERM;
+	if (IS_ERR(fud))
+		return PTR_ERR(fud);
 
 	if (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
 		return -EOPNOTSUPP;
@@ -2648,8 +2668,8 @@ static long fuse_dev_ioctl_backing_close(struct file *file, __u32 __user *argp)
 	struct fuse_dev *fud = fuse_get_dev(file);
 	int backing_id;
 
-	if (!fud)
-		return -EPERM;
+	if (IS_ERR(fud))
+		return PTR_ERR(fud);
 
 	if (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
 		return -EOPNOTSUPP;
@@ -2660,6 +2680,19 @@ static long fuse_dev_ioctl_backing_close(struct file *file, __u32 __user *argp)
 	return fuse_backing_close(fud->fc, backing_id);
 }
 
+static long fuse_dev_ioctl_sync_init(struct file *file)
+{
+	int err = -EINVAL;
+
+	mutex_lock(&fuse_mutex);
+	if (!__fuse_get_dev(file)) {
+		WRITE_ONCE(file->private_data, FUSE_DEV_SYNC_INIT);
+		err = 0;
+	}
+	mutex_unlock(&fuse_mutex);
+	return err;
+}
+
 static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 			   unsigned long arg)
 {
@@ -2675,6 +2708,9 @@ static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 	case FUSE_DEV_IOC_BACKING_CLOSE:
 		return fuse_dev_ioctl_backing_close(file, argp);
 
+	case FUSE_DEV_IOC_SYNC_INIT:
+		return fuse_dev_ioctl_sync_init(file);
+
 	default:
 		return -ENOTTY;
 	}
@@ -2683,7 +2719,7 @@ static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 #ifdef CONFIG_PROC_FS
 static void fuse_dev_show_fdinfo(struct seq_file *seq, struct file *file)
 {
-	struct fuse_dev *fud = fuse_get_dev(file);
+	struct fuse_dev *fud = __fuse_get_dev(file);
 	if (!fud)
 		return;
 
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index 7b541aeea1813f..6862fe6b7799a7 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -1140,9 +1140,9 @@ int fuse_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
 		return -EINVAL;
 
 	fud = fuse_get_dev(cmd->file);
-	if (!fud) {
+	if (IS_ERR(fud)) {
 		pr_info_ratelimited("No fuse device found\n");
-		return -ENOTCONN;
+		return PTR_ERR(fud);
 	}
 	fc = fud->fc;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 869d8a87bfb628..14c35ce12b87d6 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -7,6 +7,7 @@
 */
 
 #include "fuse_i.h"
+#include "fuse_dev_i.h"
 #include "dev_uring_i.h"
 
 #include <linux/dax.h>
@@ -34,6 +35,7 @@ MODULE_LICENSE("GPL");
 static struct kmem_cache *fuse_inode_cachep;
 struct list_head fuse_conn_list;
 DEFINE_MUTEX(fuse_mutex);
+DECLARE_WAIT_QUEUE_HEAD(fuse_dev_waitq);
 
 static int set_global_limit(const char *val, const struct kernel_param *kp);
 
@@ -1472,7 +1474,7 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
 	wake_up_all(&fc->blocked_waitq);
 }
 
-void fuse_send_init(struct fuse_mount *fm)
+static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
 {
 	struct fuse_init_args *ia;
 	u64 flags;
@@ -1531,10 +1533,29 @@ void fuse_send_init(struct fuse_mount *fm)
 	ia->args.out_args[0].value = &ia->out;
 	ia->args.force = true;
 	ia->args.nocreds = true;
-	ia->args.end = process_init_reply;
 
-	if (fuse_simple_background(fm, &ia->args, GFP_KERNEL) != 0)
-		process_init_reply(fm, &ia->args, -ENOTCONN);
+	return ia;
+}
+
+int fuse_send_init(struct fuse_mount *fm)
+{
+	struct fuse_init_args *ia = fuse_new_init(fm);
+	int err;
+
+	if (fm->fc->sync_init) {
+		err = fuse_simple_request(fm, &ia->args);
+		/* Ignore size of init reply */
+		if (err > 0)
+			err = 0;
+	} else {
+		ia->args.end = process_init_reply;
+		err = fuse_simple_background(fm, &ia->args, GFP_KERNEL);
+		if (!err)
+			return 0;
+		err = -ENOTCONN;
+	}
+	process_init_reply(fm, &ia->args, err);
+	return err;
 }
 EXPORT_SYMBOL_GPL(fuse_send_init);
 
@@ -1877,8 +1898,12 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 
 	mutex_lock(&fuse_mutex);
 	err = -EINVAL;
-	if (ctx->fudptr && *ctx->fudptr)
-		goto err_unlock;
+	if (ctx->fudptr && *ctx->fudptr) {
+		if (*ctx->fudptr == FUSE_DEV_SYNC_INIT) {
+			fc->sync_init = 1;
+		} else
+			goto err_unlock;
+	}
 
 	err = fuse_ctl_add_conn(fc);
 	if (err)
@@ -1886,8 +1911,10 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 
 	list_add_tail(&fc->entry, &fuse_conn_list);
 	sb->s_root = root_dentry;
-	if (ctx->fudptr)
+	if (ctx->fudptr) {
 		*ctx->fudptr = fud;
+		wake_up_all(&fuse_dev_waitq);
+	}
 	mutex_unlock(&fuse_mutex);
 	return 0;
 
@@ -1908,6 +1935,7 @@ EXPORT_SYMBOL_GPL(fuse_fill_super_common);
 static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc)
 {
 	struct fuse_fs_context *ctx = fsc->fs_private;
+	struct fuse_mount *fm;
 	int err;
 
 	if (!ctx->file || !ctx->rootmode_present ||
@@ -1928,8 +1956,10 @@ static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc)
 		return err;
 	/* file->private_data shall be visible on all CPUs after this */
 	smp_mb();
-	fuse_send_init(get_fuse_mount_super(sb));
-	return 0;
+
+	fm = get_fuse_mount_super(sb);
+
+	return fuse_send_init(fm);
 }
 
 /*
@@ -1990,7 +2020,7 @@ static int fuse_get_tree(struct fs_context *fsc)
 	 * Allow creating a fuse mount with an already initialized fuse
 	 * connection
 	 */
-	fud = READ_ONCE(ctx->file->private_data);
+	fud = __fuse_get_dev(ctx->file);
 	if (ctx->file->f_op == &fuse_dev_operations && fud) {
 		fsc->sget_key = fud->fc;
 		sb = sget_fc(fsc, fuse_test_super, fuse_set_no_super);

[PATCH 2/5] fuse: move the backing file idr and code into a new source file

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

iomap support for fuse is also going to want the ability to attach
backing files to a fuse filesystem.  Move the fuse_backing code into a
separate file so that both can use it.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/fuse/fuse_i.h      |   47 +++++++------
 fs/fuse/Makefile      |    2 -
 fs/fuse/backing.c     |  179 +++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/passthrough.c |  163 ---------------------------------------------
 4 files changed, 208 insertions(+), 183 deletions(-)
 create mode 100644 fs/fuse/backing.c


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 02f0138e2fe443..52db609e63eb54 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1570,29 +1570,11 @@ struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
 void fuse_file_release(struct inode *inode, struct fuse_file *ff,
 		       unsigned int open_flags, fl_owner_t id, bool isdir);
 
-/* passthrough.c */
-static inline struct fuse_backing *fuse_inode_backing(struct fuse_inode *fi)
-{
-#ifdef CONFIG_FUSE_PASSTHROUGH
-	return READ_ONCE(fi->fb);
-#else
-	return NULL;
-#endif
-}
-
-static inline struct fuse_backing *fuse_inode_backing_set(struct fuse_inode *fi,
-							  struct fuse_backing *fb)
-{
-#ifdef CONFIG_FUSE_PASSTHROUGH
-	return xchg(&fi->fb, fb);
-#else
-	return NULL;
-#endif
-}
-
+/* backing.c */
 #ifdef CONFIG_FUSE_PASSTHROUGH
 struct fuse_backing *fuse_backing_get(struct fuse_backing *fb);
 void fuse_backing_put(struct fuse_backing *fb);
+struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id);
 #else
 
 static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
@@ -1603,6 +1585,11 @@ static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
 static inline void fuse_backing_put(struct fuse_backing *fb)
 {
 }
+static inline struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
+						       int backing_id)
+{
+	return NULL;
+}
 #endif
 
 void fuse_backing_files_init(struct fuse_conn *fc);
@@ -1610,6 +1597,26 @@ void fuse_backing_files_free(struct fuse_conn *fc);
 int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map);
 int fuse_backing_close(struct fuse_conn *fc, int backing_id);
 
+/* passthrough.c */
+static inline struct fuse_backing *fuse_inode_backing(struct fuse_inode *fi)
+{
+#ifdef CONFIG_FUSE_PASSTHROUGH
+	return READ_ONCE(fi->fb);
+#else
+	return NULL;
+#endif
+}
+
+static inline struct fuse_backing *fuse_inode_backing_set(struct fuse_inode *fi,
+							  struct fuse_backing *fb)
+{
+#ifdef CONFIG_FUSE_PASSTHROUGH
+	return xchg(&fi->fb, fb);
+#else
+	return NULL;
+#endif
+}
+
 struct fuse_backing *fuse_passthrough_open(struct file *file,
 					   struct inode *inode,
 					   int backing_id);
diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 3f0f312a31c1cc..8ddd8f0b204ee5 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -13,7 +13,7 @@ obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
 fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
 fuse-y += iomode.o
 fuse-$(CONFIG_FUSE_DAX) += dax.o
-fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
+fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o backing.o
 fuse-$(CONFIG_SYSCTL) += sysctl.o
 fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
 
diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
new file mode 100644
index 00000000000000..4afda419dd1416
--- /dev/null
+++ b/fs/fuse/backing.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * FUSE passthrough to backing file.
+ *
+ * Copyright (c) 2023 CTERA Networks.
+ */
+
+#include "fuse_i.h"
+
+#include <linux/file.h>
+
+struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
+{
+	if (fb && refcount_inc_not_zero(&fb->count))
+		return fb;
+	return NULL;
+}
+
+static void fuse_backing_free(struct fuse_backing *fb)
+{
+	pr_debug("%s: fb=0x%p\n", __func__, fb);
+
+	if (fb->file)
+		fput(fb->file);
+	put_cred(fb->cred);
+	kfree_rcu(fb, rcu);
+}
+
+void fuse_backing_put(struct fuse_backing *fb)
+{
+	if (fb && refcount_dec_and_test(&fb->count))
+		fuse_backing_free(fb);
+}
+
+void fuse_backing_files_init(struct fuse_conn *fc)
+{
+	idr_init(&fc->backing_files_map);
+}
+
+static int fuse_backing_id_alloc(struct fuse_conn *fc, struct fuse_backing *fb)
+{
+	int id;
+
+	idr_preload(GFP_KERNEL);
+	spin_lock(&fc->lock);
+	/* FIXME: xarray might be space inefficient */
+	id = idr_alloc_cyclic(&fc->backing_files_map, fb, 1, 0, GFP_ATOMIC);
+	spin_unlock(&fc->lock);
+	idr_preload_end();
+
+	WARN_ON_ONCE(id == 0);
+	return id;
+}
+
+static struct fuse_backing *fuse_backing_id_remove(struct fuse_conn *fc,
+						   int id)
+{
+	struct fuse_backing *fb;
+
+	spin_lock(&fc->lock);
+	fb = idr_remove(&fc->backing_files_map, id);
+	spin_unlock(&fc->lock);
+
+	return fb;
+}
+
+static int fuse_backing_id_free(int id, void *p, void *data)
+{
+	struct fuse_backing *fb = p;
+
+	WARN_ON_ONCE(refcount_read(&fb->count) != 1);
+	fuse_backing_free(fb);
+	return 0;
+}
+
+void fuse_backing_files_free(struct fuse_conn *fc)
+{
+	idr_for_each(&fc->backing_files_map, fuse_backing_id_free, NULL);
+	idr_destroy(&fc->backing_files_map);
+}
+
+int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
+{
+	struct file *file;
+	struct super_block *backing_sb;
+	struct fuse_backing *fb = NULL;
+	int res;
+
+	pr_debug("%s: fd=%d flags=0x%x\n", __func__, map->fd, map->flags);
+
+	/* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
+	res = -EPERM;
+	if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
+		goto out;
+
+	res = -EINVAL;
+	if (map->flags || map->padding)
+		goto out;
+
+	file = fget_raw(map->fd);
+	res = -EBADF;
+	if (!file)
+		goto out;
+
+	/* read/write/splice/mmap passthrough only relevant for regular files */
+	res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
+	if (!d_is_reg(file->f_path.dentry))
+		goto out_fput;
+
+	backing_sb = file_inode(file)->i_sb;
+	res = -ELOOP;
+	if (backing_sb->s_stack_depth >= fc->max_stack_depth)
+		goto out_fput;
+
+	fb = kmalloc(sizeof(struct fuse_backing), GFP_KERNEL);
+	res = -ENOMEM;
+	if (!fb)
+		goto out_fput;
+
+	fb->file = file;
+	fb->cred = prepare_creds();
+	refcount_set(&fb->count, 1);
+
+	res = fuse_backing_id_alloc(fc, fb);
+	if (res < 0) {
+		fuse_backing_free(fb);
+		fb = NULL;
+	}
+
+out:
+	pr_debug("%s: fb=0x%p, ret=%i\n", __func__, fb, res);
+
+	return res;
+
+out_fput:
+	fput(file);
+	goto out;
+}
+
+int fuse_backing_close(struct fuse_conn *fc, int backing_id)
+{
+	struct fuse_backing *fb = NULL;
+	int err;
+
+	pr_debug("%s: backing_id=%d\n", __func__, backing_id);
+
+	/* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
+	err = -EPERM;
+	if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
+		goto out;
+
+	err = -EINVAL;
+	if (backing_id <= 0)
+		goto out;
+
+	err = -ENOENT;
+	fb = fuse_backing_id_remove(fc, backing_id);
+	if (!fb)
+		goto out;
+
+	fuse_backing_put(fb);
+	err = 0;
+out:
+	pr_debug("%s: fb=0x%p, err=%i\n", __func__, fb, err);
+
+	return err;
+}
+
+struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id)
+{
+	struct fuse_backing *fb;
+
+	rcu_read_lock();
+	fb = idr_find(&fc->backing_files_map, backing_id);
+	fb = fuse_backing_get(fb);
+	rcu_read_unlock();
+
+	return fb;
+}
diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c
index eb97ac009e75d9..e0b8d885bc81f3 100644
--- a/fs/fuse/passthrough.c
+++ b/fs/fuse/passthrough.c
@@ -144,163 +144,6 @@ ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma)
 	return backing_file_mmap(backing_file, vma, &ctx);
 }
 
-struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
-{
-	if (fb && refcount_inc_not_zero(&fb->count))
-		return fb;
-	return NULL;
-}
-
-static void fuse_backing_free(struct fuse_backing *fb)
-{
-	pr_debug("%s: fb=0x%p\n", __func__, fb);
-
-	if (fb->file)
-		fput(fb->file);
-	put_cred(fb->cred);
-	kfree_rcu(fb, rcu);
-}
-
-void fuse_backing_put(struct fuse_backing *fb)
-{
-	if (fb && refcount_dec_and_test(&fb->count))
-		fuse_backing_free(fb);
-}
-
-void fuse_backing_files_init(struct fuse_conn *fc)
-{
-	idr_init(&fc->backing_files_map);
-}
-
-static int fuse_backing_id_alloc(struct fuse_conn *fc, struct fuse_backing *fb)
-{
-	int id;
-
-	idr_preload(GFP_KERNEL);
-	spin_lock(&fc->lock);
-	/* FIXME: xarray might be space inefficient */
-	id = idr_alloc_cyclic(&fc->backing_files_map, fb, 1, 0, GFP_ATOMIC);
-	spin_unlock(&fc->lock);
-	idr_preload_end();
-
-	WARN_ON_ONCE(id == 0);
-	return id;
-}
-
-static struct fuse_backing *fuse_backing_id_remove(struct fuse_conn *fc,
-						   int id)
-{
-	struct fuse_backing *fb;
-
-	spin_lock(&fc->lock);
-	fb = idr_remove(&fc->backing_files_map, id);
-	spin_unlock(&fc->lock);
-
-	return fb;
-}
-
-static int fuse_backing_id_free(int id, void *p, void *data)
-{
-	struct fuse_backing *fb = p;
-
-	WARN_ON_ONCE(refcount_read(&fb->count) != 1);
-	fuse_backing_free(fb);
-	return 0;
-}
-
-void fuse_backing_files_free(struct fuse_conn *fc)
-{
-	idr_for_each(&fc->backing_files_map, fuse_backing_id_free, NULL);
-	idr_destroy(&fc->backing_files_map);
-}
-
-int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
-{
-	struct file *file;
-	struct super_block *backing_sb;
-	struct fuse_backing *fb = NULL;
-	int res;
-
-	pr_debug("%s: fd=%d flags=0x%x\n", __func__, map->fd, map->flags);
-
-	/* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
-	res = -EPERM;
-	if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
-		goto out;
-
-	res = -EINVAL;
-	if (map->flags || map->padding)
-		goto out;
-
-	file = fget_raw(map->fd);
-	res = -EBADF;
-	if (!file)
-		goto out;
-
-	/* read/write/splice/mmap passthrough only relevant for regular files */
-	res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
-	if (!d_is_reg(file->f_path.dentry))
-		goto out_fput;
-
-	backing_sb = file_inode(file)->i_sb;
-	res = -ELOOP;
-	if (backing_sb->s_stack_depth >= fc->max_stack_depth)
-		goto out_fput;
-
-	fb = kmalloc(sizeof(struct fuse_backing), GFP_KERNEL);
-	res = -ENOMEM;
-	if (!fb)
-		goto out_fput;
-
-	fb->file = file;
-	fb->cred = prepare_creds();
-	refcount_set(&fb->count, 1);
-
-	res = fuse_backing_id_alloc(fc, fb);
-	if (res < 0) {
-		fuse_backing_free(fb);
-		fb = NULL;
-	}
-
-out:
-	pr_debug("%s: fb=0x%p, ret=%i\n", __func__, fb, res);
-
-	return res;
-
-out_fput:
-	fput(file);
-	goto out;
-}
-
-int fuse_backing_close(struct fuse_conn *fc, int backing_id)
-{
-	struct fuse_backing *fb = NULL;
-	int err;
-
-	pr_debug("%s: backing_id=%d\n", __func__, backing_id);
-
-	/* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
-	err = -EPERM;
-	if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
-		goto out;
-
-	err = -EINVAL;
-	if (backing_id <= 0)
-		goto out;
-
-	err = -ENOENT;
-	fb = fuse_backing_id_remove(fc, backing_id);
-	if (!fb)
-		goto out;
-
-	fuse_backing_put(fb);
-	err = 0;
-out:
-	pr_debug("%s: fb=0x%p, err=%i\n", __func__, fb, err);
-
-	return err;
-}
-
 /*
  * Setup passthrough to a backing file.
  *
@@ -320,12 +163,8 @@ struct fuse_backing *fuse_passthrough_open(struct file *file,
 	if (backing_id <= 0)
 		goto out;
 
-	rcu_read_lock();
-	fb = idr_find(&fc->backing_files_map, backing_id);
-	fb = fuse_backing_get(fb);
-	rcu_read_unlock();
-
 	err = -ENOENT;
+	fb = fuse_backing_lookup(fc, backing_id);
 	if (!fb)
 		goto out;
 

[PATCH 3/5] fuse: move the passthrough-specific code back to passthrough.c

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

In preparation for iomap, move the passthrough-specific validation code
back to passthrough.c and create a new Kconfig item for conditional
compilation of backing.c.  In the next patch, iomap will share the
backing structures.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |   23 +++++++++--
 include/uapi/linux/fuse.h |    8 +++-
 fs/fuse/Kconfig           |    4 ++
 fs/fuse/Makefile          |    3 +
 fs/fuse/backing.c         |   95 ++++++++++++++++++++++++++++++++++-----------
 fs/fuse/dev.c             |    4 +-
 fs/fuse/inode.c           |    4 +-
 fs/fuse/passthrough.c     |   37 +++++++++++++++++-
 8 files changed, 144 insertions(+), 34 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 52db609e63eb54..4560687d619d76 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -96,10 +96,21 @@ struct fuse_submount_lookup {
 	struct fuse_forget_link *forget;
 };
 
+struct fuse_conn;
+
+/** Operations for subsystems that want to use a backing file */
+struct fuse_backing_ops {
+	int (*may_admin)(struct fuse_conn *fc, uint32_t flags);
+	int (*may_open)(struct fuse_conn *fc, struct file *file);
+	int (*may_close)(struct fuse_conn *fc, struct file *file);
+	unsigned int type;
+};
+
 /** Container for data related to mapping to backing file */
 struct fuse_backing {
 	struct file *file;
 	struct cred *cred;
+	const struct fuse_backing_ops *ops;
 
 	/** refcount */
 	refcount_t count;
@@ -968,7 +979,7 @@ struct fuse_conn {
 	/* New writepages go into this bucket */
 	struct fuse_sync_bucket __rcu *curr_bucket;
 
-#ifdef CONFIG_FUSE_PASSTHROUGH
+#ifdef CONFIG_FUSE_BACKING
 	/** IDR for backing files ids */
 	struct idr backing_files_map;
 #endif
@@ -1571,10 +1582,12 @@ void fuse_file_release(struct inode *inode, struct fuse_file *ff,
 		       unsigned int open_flags, fl_owner_t id, bool isdir);
 
 /* backing.c */
-#ifdef CONFIG_FUSE_PASSTHROUGH
+#ifdef CONFIG_FUSE_BACKING
 struct fuse_backing *fuse_backing_get(struct fuse_backing *fb);
 void fuse_backing_put(struct fuse_backing *fb);
-struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id);
+struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
+					 const struct fuse_backing_ops *ops,
+					 int backing_id);
 #else
 
 static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
@@ -1631,6 +1644,10 @@ static inline struct file *fuse_file_passthrough(struct fuse_file *ff)
 #endif
 }
 
+#ifdef CONFIG_FUSE_PASSTHROUGH
+extern const struct fuse_backing_ops fuse_passthrough_backing_ops;
+#endif
+
 ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, struct iov_iter *iter);
 ssize_t fuse_passthrough_splice_read(struct file *in, loff_t *ppos,
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 1d76d0332f46f6..31b80f93211b81 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1114,9 +1114,15 @@ struct fuse_notify_retrieve_in {
 	uint64_t	dummy4;
 };
 
+#define FUSE_BACKING_TYPE_MASK		(0xFF)
+#define FUSE_BACKING_TYPE_PASSTHROUGH	(0)
+#define FUSE_BACKING_MAX_TYPE		(FUSE_BACKING_TYPE_PASSTHROUGH)
+
+#define FUSE_BACKING_FLAGS_ALL		(FUSE_BACKING_TYPE_MASK)
+
 struct fuse_backing_map {
 	int32_t		fd;
-	uint32_t	flags;
+	uint32_t	flags; /* FUSE_BACKING_* */
 	uint64_t	padding;
 };
 
diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
index a774166264de69..9563fa5387a241 100644
--- a/fs/fuse/Kconfig
+++ b/fs/fuse/Kconfig
@@ -59,12 +59,16 @@ config FUSE_PASSTHROUGH
 	default y
 	depends on FUSE_FS
 	select FS_STACK
+	select FUSE_BACKING
 	help
 	  This allows bypassing FUSE server by mapping specific FUSE operations
 	  to be performed directly on a backing file.
 
 	  If you want to allow passthrough operations, answer Y.
 
+config FUSE_BACKING
+	bool
+
 config FUSE_IO_URING
 	bool "FUSE communication over io-uring"
 	default y
diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 8ddd8f0b204ee5..36be6d715b111a 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -13,7 +13,8 @@ obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
 fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
 fuse-y += iomode.o
 fuse-$(CONFIG_FUSE_DAX) += dax.o
-fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o backing.o
+fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
+fuse-$(CONFIG_FUSE_BACKING) += backing.o
 fuse-$(CONFIG_SYSCTL) += sysctl.o
 fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
 
diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 4afda419dd1416..da0dff288396ed 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -6,6 +6,7 @@
  */
 
 #include "fuse_i.h"
+#include "fuse_trace.h"
 
 #include <linux/file.h>
 
@@ -69,32 +70,53 @@ static int fuse_backing_id_free(int id, void *p, void *data)
 	struct fuse_backing *fb = p;
 
 	WARN_ON_ONCE(refcount_read(&fb->count) != 1);
+
 	fuse_backing_free(fb);
 	return 0;
 }
 
 void fuse_backing_files_free(struct fuse_conn *fc)
 {
-	idr_for_each(&fc->backing_files_map, fuse_backing_id_free, NULL);
+	idr_for_each(&fc->backing_files_map, fuse_backing_id_free, fc);
 	idr_destroy(&fc->backing_files_map);
 }
 
+static inline const struct fuse_backing_ops *
+fuse_backing_ops_from_map(const struct fuse_backing_map *map)
+{
+	switch (map->flags & FUSE_BACKING_TYPE_MASK) {
+#ifdef CONFIG_FUSE_PASSTHROUGH
+	case FUSE_BACKING_TYPE_PASSTHROUGH:
+		return &fuse_passthrough_backing_ops;
+#endif
+	default:
+		break;
+	}
+
+	return NULL;
+}
+
 int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
 {
 	struct file *file;
-	struct super_block *backing_sb;
 	struct fuse_backing *fb = NULL;
+	const struct fuse_backing_ops *ops = fuse_backing_ops_from_map(map);
+	uint32_t op_flags = map->flags & ~FUSE_BACKING_TYPE_MASK;
 	int res;
 
 	pr_debug("%s: fd=%d flags=0x%x\n", __func__, map->fd, map->flags);
 
-	/* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
-	res = -EPERM;
-	if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
+	res = -EOPNOTSUPP;
+	if (!ops)
+		goto out;
+	WARN_ON(ops->type != (map->flags & FUSE_BACKING_TYPE_MASK));
+
+	res = ops->may_admin ? ops->may_admin(fc, op_flags) : 0;
+	if (res)
 		goto out;
 
 	res = -EINVAL;
-	if (map->flags || map->padding)
+	if (map->padding)
 		goto out;
 
 	file = fget_raw(map->fd);
@@ -102,14 +124,8 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
 	if (!file)
 		goto out;
 
-	/* read/write/splice/mmap passthrough only relevant for regular files */
-	res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
-	if (!d_is_reg(file->f_path.dentry))
-		goto out_fput;
-
-	backing_sb = file_inode(file)->i_sb;
-	res = -ELOOP;
-	if (backing_sb->s_stack_depth >= fc->max_stack_depth)
+	res = ops->may_open ? ops->may_open(fc, file) : 0;
+	if (res)
 		goto out_fput;
 
 	fb = kmalloc(sizeof(struct fuse_backing), GFP_KERNEL);
@@ -119,14 +135,15 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
 
 	fb->file = file;
 	fb->cred = prepare_creds();
+	fb->ops = ops;
 	refcount_set(&fb->count, 1);
 
 	res = fuse_backing_id_alloc(fc, fb);
 	if (res < 0) {
 		fuse_backing_free(fb);
 		fb = NULL;
+		goto out;
 	}
-
 out:
 	pr_debug("%s: fb=0x%p, ret=%i\n", __func__, fb, res);
 
@@ -137,41 +154,71 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
 	goto out;
 }
 
+static struct fuse_backing *__fuse_backing_lookup(struct fuse_conn *fc,
+						  int backing_id)
+{
+	struct fuse_backing *fb;
+
+	rcu_read_lock();
+	fb = idr_find(&fc->backing_files_map, backing_id);
+	fb = fuse_backing_get(fb);
+	rcu_read_unlock();
+
+	return fb;
+}
+
 int fuse_backing_close(struct fuse_conn *fc, int backing_id)
 {
-	struct fuse_backing *fb = NULL;
+	struct fuse_backing *fb, *test_fb;
+	const struct fuse_backing_ops *ops;
 	int err;
 
 	pr_debug("%s: backing_id=%d\n", __func__, backing_id);
 
-	/* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
-	err = -EPERM;
-	if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
-		goto out;
-
 	err = -EINVAL;
 	if (backing_id <= 0)
 		goto out;
 
 	err = -ENOENT;
-	fb = fuse_backing_id_remove(fc, backing_id);
+	fb = __fuse_backing_lookup(fc, backing_id);
 	if (!fb)
 		goto out;
+	ops = fb->ops;
 
-	fuse_backing_put(fb);
+	err = ops->may_admin ? ops->may_admin(fc, 0) : 0;
+	if (err)
+		goto out_fb;
+
+	err = ops->may_close ? ops->may_close(fc, fb->file) : 0;
+	if (err)
+		goto out_fb;
+
+	err = -ENOENT;
+	test_fb = fuse_backing_id_remove(fc, backing_id);
+	if (!test_fb)
+		goto out_fb;
+
+	WARN_ON(fb != test_fb);
 	err = 0;
+	fuse_backing_put(test_fb);
+out_fb:
+	fuse_backing_put(fb);
 out:
 	pr_debug("%s: fb=0x%p, err=%i\n", __func__, fb, err);
 
 	return err;
 }
 
-struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id)
+struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
+					 const struct fuse_backing_ops *ops,
+					 int backing_id)
 {
 	struct fuse_backing *fb;
 
 	rcu_read_lock();
 	fb = idr_find(&fc->backing_files_map, backing_id);
+	if (fb && fb->ops != ops)
+		fb = NULL;
 	fb = fuse_backing_get(fb);
 	rcu_read_unlock();
 
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index e5aaf0c668bc11..281bc81f3b448b 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2654,7 +2654,7 @@ static long fuse_dev_ioctl_backing_open(struct file *file,
 	if (IS_ERR(fud))
 		return PTR_ERR(fud);
 
-	if (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
+	if (!IS_ENABLED(CONFIG_FUSE_BACKING))
 		return -EOPNOTSUPP;
 
 	if (copy_from_user(&map, argp, sizeof(map)))
@@ -2671,7 +2671,7 @@ static long fuse_dev_ioctl_backing_close(struct file *file, __u32 __user *argp)
 	if (IS_ERR(fud))
 		return PTR_ERR(fud);
 
-	if (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
+	if (!IS_ENABLED(CONFIG_FUSE_BACKING))
 		return -EOPNOTSUPP;
 
 	if (get_user(backing_id, argp))
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 14c35ce12b87d6..1e7298b2b89b58 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -995,7 +995,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
 	fc->name_max = FUSE_NAME_LOW_MAX;
 	fc->timeout.req_timeout = 0;
 
-	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
+	if (IS_ENABLED(CONFIG_FUSE_BACKING))
 		fuse_backing_files_init(fc);
 
 	INIT_LIST_HEAD(&fc->mounts);
@@ -1032,7 +1032,7 @@ void fuse_conn_put(struct fuse_conn *fc)
 			WARN_ON(atomic_read(&bucket->count) != 1);
 			kfree(bucket);
 		}
-		if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
+		if (IS_ENABLED(CONFIG_FUSE_BACKING))
 			fuse_backing_files_free(fc);
 		call_rcu(&fc->rcu, delayed_release);
 	}
diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c
index e0b8d885bc81f3..9792d7b12a775b 100644
--- a/fs/fuse/passthrough.c
+++ b/fs/fuse/passthrough.c
@@ -164,7 +164,7 @@ struct fuse_backing *fuse_passthrough_open(struct file *file,
 		goto out;
 
 	err = -ENOENT;
-	fb = fuse_backing_lookup(fc, backing_id);
+	fb = fuse_backing_lookup(fc, &fuse_passthrough_backing_ops, backing_id);
 	if (!fb)
 		goto out;
 
@@ -197,3 +197,38 @@ void fuse_passthrough_release(struct fuse_file *ff, struct fuse_backing *fb)
 	put_cred(ff->cred);
 	ff->cred = NULL;
 }
+
+static int fuse_passthrough_may_admin(struct fuse_conn *fc, unsigned int flags)
+{
+	/* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
+	if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (flags)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int fuse_passthrough_may_open(struct fuse_conn *fc, struct file *file)
+{
+	struct super_block *backing_sb;
+	int res;
+
+	/* read/write/splice/mmap passthrough only relevant for regular files */
+	res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
+	if (!d_is_reg(file->f_path.dentry))
+		return res;
+
+	backing_sb = file_inode(file)->i_sb;
+	if (backing_sb->s_stack_depth >= fc->max_stack_depth)
+		return -ELOOP;
+
+	return 0;
+}
+
+const struct fuse_backing_ops fuse_passthrough_backing_ops = {
+	.type = FUSE_BACKING_TYPE_PASSTHROUGH,
+	.may_admin = fuse_passthrough_may_admin,
+	.may_open = fuse_passthrough_may_open,
+};

[PATCH 4/5] fuse_trace: move the passthrough-specific code back to passthrough.c

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   35 +++++++++++++++++++++++++++++++++++
 fs/fuse/backing.c    |    5 +++++
 2 files changed, 40 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index bbe9ddd8c71696..286a0845dc0898 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -124,6 +124,41 @@ TRACE_EVENT(fuse_request_end,
 		  __entry->unique, __entry->len, __entry->error)
 );
 
+#ifdef CONFIG_FUSE_BACKING
+TRACE_EVENT(fuse_backing_class,
+	TP_PROTO(const struct fuse_conn *fc, unsigned int idx,
+		 const struct fuse_backing *fb),
+
+	TP_ARGS(fc, idx, fb),
+
+	TP_STRUCT__entry(
+		__field(dev_t,			connection)
+		__field(unsigned int,		idx)
+		__field(unsigned long,		ino)
+	),
+
+	TP_fast_assign(
+		struct inode *inode = file_inode(fb->file);
+
+		__entry->connection	=	fc->dev;
+		__entry->idx		=	idx;
+		__entry->ino		=	inode->i_ino;
+	),
+
+	TP_printk("connection %u idx %u ino 0x%lx",
+		  __entry->connection,
+		  __entry->idx,
+		  __entry->ino)
+);
+#define DEFINE_FUSE_BACKING_EVENT(name)		\
+DEFINE_EVENT(fuse_backing_class, name,		\
+	TP_PROTO(const struct fuse_conn *fc, unsigned int idx, \
+		 const struct fuse_backing *fb), \
+	TP_ARGS(fc, idx, fb))
+DEFINE_FUSE_BACKING_EVENT(fuse_backing_open);
+DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
+#endif /* CONFIG_FUSE_BACKING */
+
 #endif /* _TRACE_FUSE_H */
 
 #undef TRACE_INCLUDE_PATH
diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index da0dff288396ed..229c101ab46b0e 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -71,6 +71,7 @@ static int fuse_backing_id_free(int id, void *p, void *data)
 
 	WARN_ON_ONCE(refcount_read(&fb->count) != 1);
 
+	trace_fuse_backing_close((struct fuse_conn *)data, id, fb);
 	fuse_backing_free(fb);
 	return 0;
 }
@@ -144,6 +145,8 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
 		fb = NULL;
 		goto out;
 	}
+
+	trace_fuse_backing_open(fc, res, fb);
 out:
 	pr_debug("%s: fb=0x%p, ret=%i\n", __func__, fb, res);
 
@@ -193,6 +196,8 @@ int fuse_backing_close(struct fuse_conn *fc, int backing_id)
 	if (err)
 		goto out_fb;
 
+	trace_fuse_backing_close(fc, backing_id, fb);
+
 	err = -ENOENT;
 	test_fb = fuse_backing_id_remove(fc, backing_id);
 	if (!test_fb)

[PATCH 5/5] fuse: move CREATE_TRACE_POINTS to a separate file

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Before we start adding new tracepoints for fuse+iomap, move the
tracepoint creation itself to a separate source file so that we don't
have to start pulling iomap dependencies into dev.c just for the iomap
structures.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/Makefile |    3 ++-
 fs/fuse/dev.c    |    1 -
 fs/fuse/trace.c  |   13 +++++++++++++
 3 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 fs/fuse/trace.c


diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 36be6d715b111a..46041228e5be2c 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -10,7 +10,8 @@ obj-$(CONFIG_FUSE_FS) += fuse.o
 obj-$(CONFIG_CUSE) += cuse.o
 obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
 
-fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
+fuse-y := trace.o	# put trace.o first so we see ftrace errors sooner
+fuse-y += dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
 fuse-y += iomode.o
 fuse-$(CONFIG_FUSE_DAX) += dax.o
 fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 281bc81f3b448b..871877cac2acf3 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -26,7 +26,6 @@
 #include <linux/seq_file.h>
 #include <linux/nmi.h>
 
-#define CREATE_TRACE_POINTS
 #include "fuse_trace.h"
 
 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
diff --git a/fs/fuse/trace.c b/fs/fuse/trace.c
new file mode 100644
index 00000000000000..93bd72efc98cd0
--- /dev/null
+++ b/fs/fuse/trace.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "dev_uring_i.h"
+#include "fuse_i.h"
+#include "fuse_dev_i.h"
+
+#include <linux/pagemap.h>
+
+#define CREATE_TRACE_POINTS
+#include "fuse_trace.h"

[PATCH 01/28] fuse: implement the basic iomap mechanisms

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Implement functions to enable upcalling of iomap_begin and iomap_end to
userspace fuse servers.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |   35 ++++
 fs/fuse/iomap_priv.h      |   36 ++++
 include/uapi/linux/fuse.h |   90 +++++++++
 fs/fuse/Kconfig           |   32 +++
 fs/fuse/Makefile          |    1 
 fs/fuse/file_iomap.c      |  434 +++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/inode.c           |    9 +
 7 files changed, 636 insertions(+), 1 deletion(-)
 create mode 100644 fs/fuse/iomap_priv.h
 create mode 100644 fs/fuse/file_iomap.c


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 4560687d619d76..f0d408a6e12c32 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -923,6 +923,9 @@ struct fuse_conn {
 	/* Is synchronous FUSE_INIT allowed? */
 	unsigned int sync_init:1;
 
+	/* Enable fs/iomap for file operations */
+	unsigned int iomap:1;
+
 	/* Use io_uring for communication */
 	unsigned int io_uring;
 
@@ -1047,6 +1050,11 @@ static inline struct fuse_mount *get_fuse_mount_super(struct super_block *sb)
 	return sb->s_fs_info;
 }
 
+static inline const struct fuse_mount *get_fuse_mount_super_c(const struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
 {
 	return get_fuse_mount_super(sb)->fc;
@@ -1057,16 +1065,31 @@ static inline struct fuse_mount *get_fuse_mount(struct inode *inode)
 	return get_fuse_mount_super(inode->i_sb);
 }
 
+static inline const struct fuse_mount *get_fuse_mount_c(const struct inode *inode)
+{
+	return get_fuse_mount_super_c(inode->i_sb);
+}
+
 static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
 {
 	return get_fuse_mount_super(inode->i_sb)->fc;
 }
 
+static inline const struct fuse_conn *get_fuse_conn_c(const struct inode *inode)
+{
+	return get_fuse_mount_super_c(inode->i_sb)->fc;
+}
+
 static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
 {
 	return container_of(inode, struct fuse_inode, inode);
 }
 
+static inline const struct fuse_inode *get_fuse_inode_c(const struct inode *inode)
+{
+	return container_of(inode, struct fuse_inode, inode);
+}
+
 static inline u64 get_node_id(struct inode *inode)
 {
 	return get_fuse_inode(inode)->nodeid;
@@ -1666,4 +1689,16 @@ extern void fuse_sysctl_unregister(void);
 #define fuse_sysctl_unregister()	do { } while (0)
 #endif /* CONFIG_SYSCTL */
 
+#if IS_ENABLED(CONFIG_FUSE_IOMAP)
+bool fuse_iomap_enabled(void);
+
+static inline bool fuse_has_iomap(const struct inode *inode)
+{
+	return get_fuse_conn_c(inode)->iomap;
+}
+#else
+# define fuse_iomap_enabled(...)		(false)
+# define fuse_has_iomap(...)			(false)
+#endif
+
 #endif /* _FS_FUSE_I_H */
diff --git a/fs/fuse/iomap_priv.h b/fs/fuse/iomap_priv.h
new file mode 100644
index 00000000000000..243d92cb625095
--- /dev/null
+++ b/fs/fuse/iomap_priv.h
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef _FS_FUSE_IOMAP_PRIV_H
+#define _FS_FUSE_IOMAP_PRIV_H
+
+#if IS_ENABLED(CONFIG_FUSE_IOMAP)
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
+# define ASSERT(condition) do {						\
+	int __cond = !!(condition);					\
+	WARN(!__cond, "Assertion failed: %s, func: %s, line: %d", #condition, __func__, __LINE__); \
+} while (0)
+# define BAD_DATA(condition) ({						\
+	int __cond = !!(condition);					\
+	WARN(__cond, "Bad mapping: %s, func: %s, line: %d", #condition, __func__, __LINE__); \
+})
+#else
+# define ASSERT(condition)
+# define BAD_DATA(condition) ({						\
+	int __cond = !!(condition);					\
+	unlikely(__cond);						\
+})
+#endif /* CONFIG_FUSE_IOMAP_DEBUG */
+
+enum fuse_iomap_iodir {
+	READ_MAPPING,
+	WRITE_MAPPING,
+};
+
+#define EFSCORRUPTED	EUCLEAN
+
+#endif /* CONFIG_FUSE_IOMAP */
+
+#endif /* _FS_FUSE_IOMAP_PRIV_H */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 31b80f93211b81..3634cbe602cd9c 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -235,6 +235,9 @@
  *
  *  7.44
  *  - add FUSE_NOTIFY_INC_EPOCH
+ *
+ *  7.99
+ *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
  */
 
 #ifndef _LINUX_FUSE_H
@@ -270,7 +273,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 44
+#define FUSE_KERNEL_MINOR_VERSION 99
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -443,6 +446,7 @@ struct fuse_file_lock {
  * FUSE_OVER_IO_URING: Indicate that client supports io-uring
  * FUSE_REQUEST_TIMEOUT: kernel supports timing out requests.
  *			 init_out.request_timeout contains the timeout (in secs)
+ * FUSE_IOMAP: Client supports iomap for regular file operations.
  */
 #define FUSE_ASYNC_READ		(1 << 0)
 #define FUSE_POSIX_LOCKS	(1 << 1)
@@ -490,6 +494,7 @@ struct fuse_file_lock {
 #define FUSE_ALLOW_IDMAP	(1ULL << 40)
 #define FUSE_OVER_IO_URING	(1ULL << 41)
 #define FUSE_REQUEST_TIMEOUT	(1ULL << 42)
+#define FUSE_IOMAP		(1ULL << 43)
 
 /**
  * CUSE INIT request/reply flags
@@ -658,6 +663,9 @@ enum fuse_opcode {
 	FUSE_TMPFILE		= 51,
 	FUSE_STATX		= 52,
 
+	FUSE_IOMAP_BEGIN	= 4094,
+	FUSE_IOMAP_END		= 4095,
+
 	/* CUSE specific operations */
 	CUSE_INIT		= 4096,
 
@@ -1297,4 +1305,84 @@ struct fuse_uring_cmd_req {
 	uint8_t padding[6];
 };
 
+/* mapping types; see corresponding IOMAP_TYPE_ */
+#define FUSE_IOMAP_TYPE_HOLE		(0)
+#define FUSE_IOMAP_TYPE_DELALLOC	(1)
+#define FUSE_IOMAP_TYPE_MAPPED		(2)
+#define FUSE_IOMAP_TYPE_UNWRITTEN	(3)
+#define FUSE_IOMAP_TYPE_INLINE		(4)
+
+/* fuse-specific mapping type indicating that writes use the read mapping */
+#define FUSE_IOMAP_TYPE_PURE_OVERWRITE	(255)
+
+#define FUSE_IOMAP_DEV_NULL		(0U)	/* null device cookie */
+
+/* mapping flags passed back from iomap_begin; see corresponding IOMAP_F_ */
+#define FUSE_IOMAP_F_NEW		(1U << 0)
+#define FUSE_IOMAP_F_DIRTY		(1U << 1)
+#define FUSE_IOMAP_F_SHARED		(1U << 2)
+#define FUSE_IOMAP_F_MERGED		(1U << 3)
+#define FUSE_IOMAP_F_BOUNDARY		(1U << 4)
+#define FUSE_IOMAP_F_ANON_WRITE		(1U << 5)
+#define FUSE_IOMAP_F_ATOMIC_BIO		(1U << 6)
+
+/* fuse-specific mapping flag asking for ->iomap_end call */
+#define FUSE_IOMAP_F_WANT_IOMAP_END	(1U << 7)
+
+/* mapping flags passed to iomap_end */
+#define FUSE_IOMAP_F_SIZE_CHANGED	(1U << 8)
+#define FUSE_IOMAP_F_STALE		(1U << 9)
+
+/* operation flags from iomap; see corresponding IOMAP_* */
+#define FUSE_IOMAP_OP_WRITE		(1U << 0)
+#define FUSE_IOMAP_OP_ZERO		(1U << 1)
+#define FUSE_IOMAP_OP_REPORT		(1U << 2)
+#define FUSE_IOMAP_OP_FAULT		(1U << 3)
+#define FUSE_IOMAP_OP_DIRECT		(1U << 4)
+#define FUSE_IOMAP_OP_NOWAIT		(1U << 5)
+#define FUSE_IOMAP_OP_OVERWRITE_ONLY	(1U << 6)
+#define FUSE_IOMAP_OP_UNSHARE		(1U << 7)
+#define FUSE_IOMAP_OP_DAX		(1U << 8)
+#define FUSE_IOMAP_OP_ATOMIC		(1U << 9)
+#define FUSE_IOMAP_OP_DONTCACHE		(1U << 10)
+
+#define FUSE_IOMAP_NULL_ADDR		(-1ULL)	/* addr is not valid */
+
+struct fuse_iomap_io {
+	uint64_t offset;	/* file offset of mapping, bytes */
+	uint64_t length;	/* length of mapping, bytes */
+	uint64_t addr;		/* disk offset of mapping, bytes */
+	uint16_t type;		/* FUSE_IOMAP_TYPE_* */
+	uint16_t flags;		/* FUSE_IOMAP_F_* */
+	uint32_t dev;		/* device cookie */
+};
+
+struct fuse_iomap_begin_in {
+	uint32_t opflags;	/* FUSE_IOMAP_OP_* */
+	uint32_t reserved;	/* zero */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+	uint64_t pos;		/* file position, in bytes */
+	uint64_t count;		/* operation length, in bytes */
+};
+
+struct fuse_iomap_begin_out {
+	/* read file data from here */
+	struct fuse_iomap_io	read;
+
+	/* write file data to here, if applicable */
+	struct fuse_iomap_io	write;
+};
+
+struct fuse_iomap_end_in {
+	uint32_t opflags;	/* FUSE_IOMAP_OP_* */
+	uint32_t reserved;	/* zero */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+	uint64_t pos;		/* file position, in bytes */
+	uint64_t count;		/* operation length, in bytes */
+	int64_t written;	/* bytes processed */
+
+	/* mapping that the kernel acted upon */
+	struct fuse_iomap_io	map;
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
index 9563fa5387a241..67dfe300bf2e07 100644
--- a/fs/fuse/Kconfig
+++ b/fs/fuse/Kconfig
@@ -69,6 +69,38 @@ config FUSE_PASSTHROUGH
 config FUSE_BACKING
 	bool
 
+config FUSE_IOMAP
+	bool "FUSE file IO over iomap"
+	default n
+	depends on FUSE_FS
+	depends on BLOCK
+	select FS_IOMAP
+	help
+	  Enable fuse servers to operate the regular file I/O path through
+	  the fs-iomap library in the kernel.  This enables higher performance
+	  userspace filesystems by keeping the performance critical parts in
+	  the kernel while delegating the difficult metadata parsing parts to
+	  an easily-contained userspace program.
+
+	  This feature is considered EXPERIMENTAL.  Use with caution!
+
+	  If unsure, say N.
+
+config FUSE_IOMAP_BY_DEFAULT
+	bool "FUSE file I/O over iomap by default"
+	default n
+	depends on FUSE_IOMAP
+	help
+	  Enable sending FUSE file I/O over iomap by default.
+
+config FUSE_IOMAP_DEBUG
+	bool "Debug FUSE file IO over iomap"
+	default n
+	depends on FUSE_IOMAP
+	help
+	  Enable debugging assertions for the fuse iomap code paths and logging
+	  of bad iomap file mapping data being sent to the kernel.
+
 config FUSE_IO_URING
 	bool "FUSE communication over io-uring"
 	default y
diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 46041228e5be2c..27be39317701d6 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -18,5 +18,6 @@ fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
 fuse-$(CONFIG_FUSE_BACKING) += backing.o
 fuse-$(CONFIG_SYSCTL) += sysctl.o
 fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
+fuse-$(CONFIG_FUSE_IOMAP) += file_iomap.o
 
 virtiofs-y := virtio_fs.o
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
new file mode 100644
index 00000000000000..dda757768d3ea6
--- /dev/null
+++ b/fs/fuse/file_iomap.c
@@ -0,0 +1,434 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include <linux/iomap.h>
+#include "fuse_i.h"
+#include "fuse_trace.h"
+#include "iomap_priv.h"
+
+static bool __read_mostly enable_iomap =
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_BY_DEFAULT)
+	true;
+#else
+	false;
+#endif
+module_param(enable_iomap, bool, 0644);
+MODULE_PARM_DESC(enable_iomap, "Enable file I/O through iomap");
+
+bool fuse_iomap_enabled(void)
+{
+	/* Don't let anyone touch iomap until the end of the patchset. */
+	return false;
+
+	/*
+	 * There are fears that a fuse+iomap server could somehow DoS the
+	 * system by doing things like going out to lunch during a writeback
+	 * related iomap request.  Only allow iomap access if the fuse server
+	 * has rawio capabilities since those processes can mess things up
+	 * quite well even without our help.
+	 */
+	return enable_iomap && has_capability_noaudit(current, CAP_SYS_RAWIO);
+}
+
+/* Convert IOMAP_* mapping types to FUSE_IOMAP_TYPE_* */
+#define XMAP(word) \
+	case IOMAP_##word: \
+		return FUSE_IOMAP_TYPE_##word
+static inline uint16_t fuse_iomap_type_to_server(uint16_t iomap_type)
+{
+	switch (iomap_type) {
+	XMAP(HOLE);
+	XMAP(DELALLOC);
+	XMAP(MAPPED);
+	XMAP(UNWRITTEN);
+	XMAP(INLINE);
+	default:
+		ASSERT(0);
+	}
+	return 0;
+}
+#undef XMAP
+
+/* Convert FUSE_IOMAP_TYPE_* to IOMAP_* mapping types */
+#define XMAP(word) \
+	case FUSE_IOMAP_TYPE_##word: \
+		return IOMAP_##word
+static inline uint16_t fuse_iomap_type_from_server(uint16_t fuse_type)
+{
+	switch (fuse_type) {
+	XMAP(HOLE);
+	XMAP(DELALLOC);
+	XMAP(MAPPED);
+	XMAP(UNWRITTEN);
+	XMAP(INLINE);
+	default:
+		ASSERT(0);
+	}
+	return 0;
+}
+#undef XMAP
+
+/* Validate FUSE_IOMAP_TYPE_* */
+static inline bool fuse_iomap_check_type(uint16_t fuse_type)
+{
+	switch (fuse_type) {
+	case FUSE_IOMAP_TYPE_HOLE:
+	case FUSE_IOMAP_TYPE_DELALLOC:
+	case FUSE_IOMAP_TYPE_MAPPED:
+	case FUSE_IOMAP_TYPE_UNWRITTEN:
+	case FUSE_IOMAP_TYPE_INLINE:
+	case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
+		return true;
+	}
+
+	return false;
+}
+
+#define FUSE_IOMAP_F_ALL (FUSE_IOMAP_F_NEW | \
+			  FUSE_IOMAP_F_DIRTY | \
+			  FUSE_IOMAP_F_SHARED | \
+			  FUSE_IOMAP_F_MERGED | \
+			  FUSE_IOMAP_F_BOUNDARY | \
+			  FUSE_IOMAP_F_ANON_WRITE | \
+			  FUSE_IOMAP_F_ATOMIC_BIO | \
+			  FUSE_IOMAP_F_WANT_IOMAP_END)
+
+static inline bool fuse_iomap_check_flags(uint16_t flags)
+{
+	return (flags & ~FUSE_IOMAP_F_ALL) == 0;
+}
+
+/* Convert IOMAP_F_* mapping state flags to FUSE_IOMAP_F_* */
+#define XMAP(word) \
+	if (iomap_f_flags & IOMAP_F_##word) \
+		ret |= FUSE_IOMAP_F_##word
+#define YMAP(iword, oword) \
+	if (iomap_f_flags & IOMAP_F_##iword) \
+		ret |= FUSE_IOMAP_F_##oword
+static inline uint16_t fuse_iomap_flags_to_server(uint16_t iomap_f_flags)
+{
+	uint16_t ret = 0;
+
+	XMAP(NEW);
+	XMAP(DIRTY);
+	XMAP(SHARED);
+	XMAP(MERGED);
+	XMAP(BOUNDARY);
+	XMAP(ANON_WRITE);
+	XMAP(ATOMIC_BIO);
+	YMAP(PRIVATE, WANT_IOMAP_END);
+
+	XMAP(SIZE_CHANGED);
+	XMAP(STALE);
+
+	return ret;
+}
+#undef YMAP
+#undef XMAP
+
+/* Convert FUSE_IOMAP_F_* to IOMAP_F_* mapping state flags */
+#define XMAP(word) \
+	if (fuse_f_flags & FUSE_IOMAP_F_##word) \
+		ret |= IOMAP_F_##word
+#define YMAP(iword, oword) \
+	if (fuse_f_flags & FUSE_IOMAP_F_##iword) \
+		ret |= IOMAP_F_##oword
+static inline uint16_t fuse_iomap_flags_from_server(uint16_t fuse_f_flags)
+{
+	uint16_t ret = 0;
+
+	XMAP(NEW);
+	XMAP(DIRTY);
+	XMAP(SHARED);
+	XMAP(MERGED);
+	XMAP(BOUNDARY);
+	XMAP(ANON_WRITE);
+	XMAP(ATOMIC_BIO);
+	YMAP(WANT_IOMAP_END, PRIVATE);
+
+	return ret;
+}
+#undef YMAP
+#undef XMAP
+
+/* Convert IOMAP_* operation flags to FUSE_IOMAP_OP_* */
+#define XMAP(word) \
+	if (iomap_op_flags & IOMAP_##word) \
+		ret |= FUSE_IOMAP_OP_##word
+static inline uint32_t fuse_iomap_op_to_server(unsigned iomap_op_flags)
+{
+	uint32_t ret = 0;
+
+	XMAP(WRITE);
+	XMAP(ZERO);
+	XMAP(REPORT);
+	XMAP(FAULT);
+	XMAP(DIRECT);
+	XMAP(NOWAIT);
+	XMAP(OVERWRITE_ONLY);
+	XMAP(UNSHARE);
+	XMAP(DAX);
+	XMAP(ATOMIC);
+	XMAP(DONTCACHE);
+
+	return ret;
+}
+#undef XMAP
+
+/* Validate an iomap mapping. */
+static inline bool fuse_iomap_check_mapping(const struct inode *inode,
+					    const struct fuse_iomap_io *map,
+					    enum fuse_iomap_iodir iodir)
+{
+	const unsigned int blocksize = i_blocksize(inode);
+	uint64_t end;
+
+	/* Type and flags must be known */
+	if (BAD_DATA(!fuse_iomap_check_type(map->type)))
+		return false;
+	if (BAD_DATA(!fuse_iomap_check_flags(map->flags)))
+		return false;
+
+	/* No zero-length mappings */
+	if (BAD_DATA(map->length == 0))
+		return false;
+
+	/* File range must be aligned to blocksize */
+	if (BAD_DATA(!IS_ALIGNED(map->offset, blocksize)))
+		return false;
+	if (BAD_DATA(!IS_ALIGNED(map->length, blocksize)))
+		return false;
+
+	/* No overflows in the file range */
+	if (BAD_DATA(check_add_overflow(map->offset, map->length, &end)))
+		return false;
+
+	/* File range cannot start past maxbytes */
+	if (BAD_DATA(map->offset >= inode->i_sb->s_maxbytes))
+		return false;
+
+	switch (map->type) {
+	case FUSE_IOMAP_TYPE_MAPPED:
+	case FUSE_IOMAP_TYPE_UNWRITTEN:
+		/* Mappings backed by space must have a device/addr */
+		if (BAD_DATA(map->dev == FUSE_IOMAP_DEV_NULL))
+			return false;
+		if (BAD_DATA(map->addr == FUSE_IOMAP_NULL_ADDR))
+			return false;
+		break;
+	case FUSE_IOMAP_TYPE_DELALLOC:
+	case FUSE_IOMAP_TYPE_HOLE:
+	case FUSE_IOMAP_TYPE_INLINE:
+		/* Mappings not backed by space cannot have a device addr. */
+		if (BAD_DATA(map->dev != FUSE_IOMAP_DEV_NULL))
+			return false;
+		if (BAD_DATA(map->addr != FUSE_IOMAP_NULL_ADDR))
+			return false;
+		break;
+	case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
+		/* "Pure overwrite" only allowed for write mapping */
+		if (BAD_DATA(iodir != WRITE_MAPPING))
+			return false;
+		break;
+	default:
+		/* should have been caught already */
+		ASSERT(0);
+		return false;
+	}
+
+	/* XXX: we don't support devices yet */
+	if (BAD_DATA(map->dev != FUSE_IOMAP_DEV_NULL))
+		return false;
+
+	/* No overflows in the device range, if supplied */
+	if (map->addr != FUSE_IOMAP_NULL_ADDR &&
+	    BAD_DATA(check_add_overflow(map->addr, map->length, &end)))
+		return false;
+
+	return true;
+}
+
+/* Convert a mapping from the server into something the kernel can use */
+static inline void fuse_iomap_from_server(struct inode *inode,
+					  struct iomap *iomap,
+					  const struct fuse_iomap_io *fmap)
+{
+	iomap->addr = fmap->addr;
+	iomap->offset = fmap->offset;
+	iomap->length = fmap->length;
+	iomap->type = fuse_iomap_type_from_server(fmap->type);
+	iomap->flags = fuse_iomap_flags_from_server(fmap->flags);
+	iomap->bdev = inode->i_sb->s_bdev; /* XXX */
+}
+
+/* Convert a mapping from the kernel into something the server can use */
+static inline void fuse_iomap_to_server(struct fuse_iomap_io *fmap,
+					const struct iomap *iomap)
+{
+	fmap->addr = FUSE_IOMAP_NULL_ADDR; /* XXX */
+	fmap->offset = iomap->offset;
+	fmap->length = iomap->length;
+	fmap->type = fuse_iomap_type_to_server(iomap->type);
+	fmap->flags = fuse_iomap_flags_to_server(iomap->flags);
+	fmap->dev = FUSE_IOMAP_DEV_NULL; /* XXX */
+}
+
+/* Check the incoming _begin mappings to make sure they're not nonsense. */
+static inline int
+fuse_iomap_begin_validate(const struct inode *inode,
+			  unsigned opflags, loff_t pos,
+			  const struct fuse_iomap_begin_out *outarg)
+{
+	/* Make sure the mappings aren't garbage */
+	if (!fuse_iomap_check_mapping(inode, &outarg->read, READ_MAPPING))
+		return -EFSCORRUPTED;
+
+	if (!fuse_iomap_check_mapping(inode, &outarg->write, WRITE_MAPPING))
+		return -EFSCORRUPTED;
+
+	/*
+	 * Must have returned a mapping for at least the first byte in the
+	 * range.  The main mapping check already validated that the length
+	 * is nonzero and there is no overflow in computing end.
+	 */
+	if (BAD_DATA(outarg->read.offset > pos))
+		return -EFSCORRUPTED;
+	if (BAD_DATA(outarg->write.offset > pos))
+		return -EFSCORRUPTED;
+
+	if (BAD_DATA(outarg->read.offset + outarg->read.length <= pos))
+		return -EFSCORRUPTED;
+	if (BAD_DATA(outarg->write.offset + outarg->write.length <= pos))
+		return -EFSCORRUPTED;
+
+	return 0;
+}
+
+static inline bool fuse_is_iomap_file_write(unsigned int opflags)
+{
+	return opflags & (IOMAP_WRITE | IOMAP_ZERO | IOMAP_UNSHARE);
+}
+
+static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
+			    unsigned opflags, struct iomap *iomap,
+			    struct iomap *srcmap)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_iomap_begin_in inarg = {
+		.attr_ino = fi->orig_ino,
+		.opflags = fuse_iomap_op_to_server(opflags),
+		.pos = pos,
+		.count = count,
+	};
+	struct fuse_iomap_begin_out outarg = { };
+	struct fuse_mount *fm = get_fuse_mount(inode);
+	FUSE_ARGS(args);
+	int err;
+
+	args.opcode = FUSE_IOMAP_BEGIN;
+	args.nodeid = get_node_id(inode);
+	args.in_numargs = 1;
+	args.in_args[0].size = sizeof(inarg);
+	args.in_args[0].value = &inarg;
+	args.out_numargs = 1;
+	args.out_args[0].size = sizeof(outarg);
+	args.out_args[0].value = &outarg;
+	err = fuse_simple_request(fm, &args);
+	if (err)
+		return err;
+
+	err = fuse_iomap_begin_validate(inode, opflags, pos, &outarg);
+	if (err)
+		return err;
+
+	if (fuse_is_iomap_file_write(opflags) &&
+	    outarg.write.type != FUSE_IOMAP_TYPE_PURE_OVERWRITE) {
+		/*
+		 * For an out of place write, we must supply the write mapping
+		 * via @iomap, and the read mapping via @srcmap.
+		 */
+		fuse_iomap_from_server(inode, iomap, &outarg.write);
+		fuse_iomap_from_server(inode, srcmap, &outarg.read);
+	} else {
+		/*
+		 * For everything else (reads, reporting, and pure overwrites),
+		 * we can return the sole mapping through @iomap and leave
+		 * @srcmap unchanged from its default (HOLE).
+		 */
+		fuse_iomap_from_server(inode, iomap, &outarg.read);
+	}
+
+	return 0;
+}
+
+/* Decide if we send FUSE_IOMAP_END to the fuse server */
+static bool fuse_should_send_iomap_end(const struct iomap *iomap,
+				       unsigned int opflags, loff_t count,
+				       ssize_t written)
+{
+	/* fuse server demanded an iomap_end call. */
+	if (iomap->flags & FUSE_IOMAP_F_WANT_IOMAP_END)
+		return true;
+
+	/* Reads and reporting should never affect the filesystem metadata */
+	if (!fuse_is_iomap_file_write(opflags))
+		return false;
+
+	/* Appending writes get an iomap_end call */
+	if (iomap->flags & IOMAP_F_SIZE_CHANGED)
+		return true;
+
+	/* Short writes get an iomap_end call to clean up delalloc */
+	return written < count;
+}
+
+static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t count,
+			  ssize_t written, unsigned opflags,
+			  struct iomap *iomap)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_mount *fm = get_fuse_mount(inode);
+	int err = 0;
+
+	if (fuse_should_send_iomap_end(iomap, opflags, count, written)) {
+		struct fuse_iomap_end_in inarg = {
+			.opflags = fuse_iomap_op_to_server(opflags),
+			.attr_ino = fi->orig_ino,
+			.pos = pos,
+			.count = count,
+			.written = written,
+		};
+		FUSE_ARGS(args);
+
+		fuse_iomap_to_server(&inarg.map, iomap);
+
+		args.opcode = FUSE_IOMAP_END;
+		args.nodeid = get_node_id(inode);
+		args.in_numargs = 1;
+		args.in_args[0].size = sizeof(inarg);
+		args.in_args[0].value = &inarg;
+		err = fuse_simple_request(fm, &args);
+		switch (err) {
+		case -ENOSYS:
+			/*
+			 * libfuse returns ENOSYS for servers that don't
+			 * implement iomap_end
+			 */
+			err = 0;
+			break;
+		case 0:
+			break;
+		default:
+			break;
+		}
+	}
+
+	return err;
+}
+
+const struct iomap_ops fuse_iomap_ops = {
+	.iomap_begin		= fuse_iomap_begin,
+	.iomap_end		= fuse_iomap_end,
+};
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 1e7298b2b89b58..32f4b7c9a20a8a 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1448,6 +1448,13 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
 
 			if (flags & FUSE_REQUEST_TIMEOUT)
 				timeout = arg->request_timeout;
+
+			if ((flags & FUSE_IOMAP) && fuse_iomap_enabled()) {
+				fc->local_fs = 1;
+				fc->iomap = 1;
+				printk(KERN_WARNING
+ "fuse: EXPERIMENTAL iomap feature enabled.  Use at your own risk!");
+			}
 		} else {
 			ra_pages = fc->max_read / PAGE_SIZE;
 			fc->no_lock = 1;
@@ -1516,6 +1523,8 @@ static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
 	 */
 	if (fuse_uring_enabled())
 		flags |= FUSE_OVER_IO_URING;
+	if (fuse_iomap_enabled())
+		flags |= FUSE_IOMAP;
 
 	ia->in.flags = flags;
 	ia->in.flags2 = flags >> 32;

[PATCH 02/28] fuse_trace: implement the basic iomap mechanisms

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |  295 ++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/iomap_priv.h |    6 +
 fs/fuse/file_iomap.c |   12 ++
 3 files changed, 312 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 286a0845dc0898..ef94f07cbbf2d4 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -58,6 +58,8 @@
 	EM( FUSE_SYNCFS,		"FUSE_SYNCFS")		\
 	EM( FUSE_TMPFILE,		"FUSE_TMPFILE")		\
 	EM( FUSE_STATX,			"FUSE_STATX")		\
+	EM( FUSE_IOMAP_BEGIN,		"FUSE_IOMAP_BEGIN")	\
+	EM( FUSE_IOMAP_END,		"FUSE_IOMAP_END")	\
 	EMe(CUSE_INIT,			"CUSE_INIT")
 
 /*
@@ -77,6 +79,54 @@ OPCODES
 #define EM(a, b)	{a, b},
 #define EMe(a, b)	{a, b}
 
+/* tracepoint boilerplate so we don't have to keep doing this */
+#define FUSE_INODE_FIELDS \
+		__field(dev_t,			connection) \
+		__field(uint64_t,		ino) \
+		__field(uint64_t,		nodeid) \
+		__field(loff_t,			isize)
+
+#define FUSE_INODE_ASSIGN(inode, fi, fm) \
+		const struct fuse_inode *fi = get_fuse_inode_c(inode); \
+		const struct fuse_mount *fm = get_fuse_mount_c(inode); \
+\
+		__entry->connection	=	(fm)->fc->dev; \
+		__entry->ino		=	(fi)->orig_ino; \
+		__entry->nodeid		=	(fi)->nodeid; \
+		__entry->isize		=	i_size_read(inode)
+
+#define FUSE_INODE_FMT \
+		"connection %u ino %llu nodeid %llu isize 0x%llx"
+
+#define FUSE_INODE_PRINTK_ARGS \
+		__entry->connection, \
+		__entry->ino, \
+		__entry->nodeid, \
+		__entry->isize
+
+#define FUSE_FILE_RANGE_FIELDS(prefix) \
+		__field(loff_t,			prefix##offset) \
+		__field(loff_t,			prefix##length)
+
+#define FUSE_FILE_RANGE_FMT(prefix) \
+		" " prefix "pos 0x%llx length 0x%llx"
+
+#define FUSE_FILE_RANGE_PRINTK_ARGS(prefix) \
+		__entry->prefix##offset, \
+		__entry->prefix##length
+
+/* combinations of boilerplate to reduce typing further */
+#define FUSE_IO_RANGE_FIELDS(prefix) \
+		FUSE_INODE_FIELDS \
+		FUSE_FILE_RANGE_FIELDS(prefix)
+
+#define FUSE_IO_RANGE_FMT(prefix) \
+		FUSE_INODE_FMT FUSE_FILE_RANGE_FMT(prefix)
+
+#define FUSE_IO_RANGE_PRINTK_ARGS(prefix) \
+		FUSE_INODE_PRINTK_ARGS, \
+		FUSE_FILE_RANGE_PRINTK_ARGS(prefix)
+
 TRACE_EVENT(fuse_request_send,
 	TP_PROTO(const struct fuse_req *req),
 
@@ -159,6 +209,251 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_open);
 DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 #endif /* CONFIG_FUSE_BACKING */
 
+#if IS_ENABLED(CONFIG_FUSE_IOMAP)
+
+/* tracepoint boilerplate so we don't have to keep doing this */
+#define FUSE_IOMAP_OPFLAGS_FIELD \
+		__field(unsigned,		opflags)
+
+#define FUSE_IOMAP_OPFLAGS_FMT \
+		" opflags (%s)"
+
+#define FUSE_IOMAP_OPFLAGS_PRINTK_ARG \
+		__print_flags(__entry->opflags, "|", FUSE_IOMAP_OP_STRINGS)
+
+#define FUSE_IOMAP_MAP_FIELDS(prefix) \
+		__field(uint64_t,		prefix##offset) \
+		__field(uint64_t,		prefix##length) \
+		__field(uint64_t,		prefix##addr) \
+		__field(uint32_t,		prefix##dev) \
+		__field(uint16_t,		prefix##type) \
+		__field(uint16_t,		prefix##flags)
+
+#define FUSE_IOMAP_MAP_FMT(prefix) \
+		" " prefix "offset 0x%llx length 0x%llx type %s dev %u addr 0x%llx mapflags (%s)"
+
+#define FUSE_IOMAP_MAP_PRINTK_ARGS(prefix) \
+		__entry->prefix##offset, \
+		__entry->prefix##length, \
+		__print_symbolic(__entry->prefix##type, FUSE_IOMAP_TYPE_STRINGS), \
+		__entry->prefix##dev, \
+		__entry->prefix##addr, \
+		__print_flags(__entry->prefix##flags, "|", FUSE_IOMAP_F_STRINGS)
+
+/* combinations of boilerplate to reduce typing further */
+#define FUSE_IOMAP_OP_FIELDS(prefix) \
+		FUSE_INODE_FIELDS \
+		FUSE_IOMAP_OPFLAGS_FIELD \
+		FUSE_FILE_RANGE_FIELDS(prefix)
+
+#define FUSE_IOMAP_OP_FMT(prefix) \
+		FUSE_INODE_FMT FUSE_IOMAP_OPFLAGS_FMT FUSE_FILE_RANGE_FMT(prefix)
+
+#define FUSE_IOMAP_OP_PRINTK_ARGS(prefix) \
+		FUSE_INODE_PRINTK_ARGS, \
+		FUSE_IOMAP_OPFLAGS_PRINTK_ARG, \
+		FUSE_FILE_RANGE_PRINTK_ARGS(prefix)
+
+/* string decoding */
+#define FUSE_IOMAP_F_STRINGS \
+	{ FUSE_IOMAP_F_NEW,			"new" }, \
+	{ FUSE_IOMAP_F_DIRTY,			"dirty" }, \
+	{ FUSE_IOMAP_F_SHARED,			"shared" }, \
+	{ FUSE_IOMAP_F_MERGED,			"merged" }, \
+	{ FUSE_IOMAP_F_BOUNDARY,		"boundary" }, \
+	{ FUSE_IOMAP_F_ANON_WRITE,		"anon_write" }, \
+	{ FUSE_IOMAP_F_ATOMIC_BIO,		"atomic" }, \
+	{ FUSE_IOMAP_F_WANT_IOMAP_END,		"iomap_end" }, \
+	{ FUSE_IOMAP_F_SIZE_CHANGED,		"append" }, \
+	{ FUSE_IOMAP_F_STALE,			"stale" }
+
+#define FUSE_IOMAP_OP_STRINGS \
+	{ FUSE_IOMAP_OP_WRITE,			"write" }, \
+	{ FUSE_IOMAP_OP_ZERO,			"zero" }, \
+	{ FUSE_IOMAP_OP_REPORT,			"report" }, \
+	{ FUSE_IOMAP_OP_FAULT,			"fault" }, \
+	{ FUSE_IOMAP_OP_DIRECT,			"direct" }, \
+	{ FUSE_IOMAP_OP_NOWAIT,			"nowait" }, \
+	{ FUSE_IOMAP_OP_OVERWRITE_ONLY,		"overwrite" }, \
+	{ FUSE_IOMAP_OP_UNSHARE,		"unshare" }, \
+	{ FUSE_IOMAP_OP_DAX,			"fsdax" }, \
+	{ FUSE_IOMAP_OP_ATOMIC,			"atomic" }, \
+	{ FUSE_IOMAP_OP_DONTCACHE,		"dontcache" }
+
+#define FUSE_IOMAP_TYPE_STRINGS \
+	{ FUSE_IOMAP_TYPE_PURE_OVERWRITE,	"overwrite" }, \
+	{ FUSE_IOMAP_TYPE_HOLE,			"hole" }, \
+	{ FUSE_IOMAP_TYPE_DELALLOC,		"delalloc" }, \
+	{ FUSE_IOMAP_TYPE_MAPPED,		"mapped" }, \
+	{ FUSE_IOMAP_TYPE_UNWRITTEN,		"unwritten" }, \
+	{ FUSE_IOMAP_TYPE_INLINE,		"inline" }
+
+DECLARE_EVENT_CLASS(fuse_iomap_check_class,
+	TP_PROTO(const char *func, int line, const char *condition),
+
+	TP_ARGS(func, line, condition),
+
+	TP_STRUCT__entry(
+		__string(func,			func)
+		__field(int,			line)
+		__string(condition,		condition)
+	),
+
+	TP_fast_assign(
+		__assign_str(func);
+		__assign_str(condition);
+		__entry->line		=	line;
+	),
+
+	TP_printk("func %s line %d condition %s", __get_str(func),
+		  __entry->line, __get_str(condition))
+);
+#define DEFINE_FUSE_IOMAP_CHECK_EVENT(name)	\
+DEFINE_EVENT(fuse_iomap_check_class, name,	\
+	TP_PROTO(const char *func, int line, const char *condition), \
+	TP_ARGS(func, line, condition))
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
+DEFINE_FUSE_IOMAP_CHECK_EVENT(fuse_iomap_assert);
+#endif
+DEFINE_FUSE_IOMAP_CHECK_EVENT(fuse_iomap_bad_data);
+
+TRACE_EVENT(fuse_iomap_begin,
+	TP_PROTO(const struct inode *inode, loff_t pos, loff_t count,
+		 unsigned opflags),
+
+	TP_ARGS(inode, pos, count, opflags),
+
+	TP_STRUCT__entry(
+		FUSE_IOMAP_OP_FIELDS()
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	pos;
+		__entry->length		=	count;
+		__entry->opflags	=	opflags;
+	),
+
+	TP_printk(FUSE_IOMAP_OP_FMT(),
+		  FUSE_IOMAP_OP_PRINTK_ARGS())
+);
+
+TRACE_EVENT(fuse_iomap_begin_error,
+	TP_PROTO(const struct inode *inode, loff_t pos, loff_t count,
+		 unsigned opflags, int error),
+
+	TP_ARGS(inode, pos, count, opflags, error),
+
+	TP_STRUCT__entry(
+		FUSE_IOMAP_OP_FIELDS()
+		__field(int,			error)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	pos;
+		__entry->length		=	count;
+		__entry->opflags	=	opflags;
+		__entry->error		=	error;
+	),
+
+	TP_printk(FUSE_IOMAP_OP_FMT() " err %d",
+		  FUSE_IOMAP_OP_PRINTK_ARGS(),
+		  __entry->error)
+);
+
+DECLARE_EVENT_CLASS(fuse_iomap_mapping_class,
+	TP_PROTO(const struct inode *inode, const struct fuse_iomap_io *map),
+
+	TP_ARGS(inode, map),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		FUSE_IOMAP_MAP_FIELDS(map)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->mapoffset	=	map->offset;
+		__entry->maplength	=	map->length;
+		__entry->mapdev		=	map->dev;
+		__entry->mapaddr	=	map->addr;
+		__entry->maptype	=	map->type;
+		__entry->mapflags	=	map->flags;
+	),
+
+	TP_printk(FUSE_INODE_FMT FUSE_IOMAP_MAP_FMT(),
+		  FUSE_INODE_PRINTK_ARGS,
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map))
+);
+#define DEFINE_FUSE_IOMAP_MAPPING_EVENT(name)	\
+DEFINE_EVENT(fuse_iomap_mapping_class, name,	\
+	TP_PROTO(const struct inode *inode, const struct fuse_iomap_io *map), \
+	TP_ARGS(inode, map))
+DEFINE_FUSE_IOMAP_MAPPING_EVENT(fuse_iomap_read_map);
+DEFINE_FUSE_IOMAP_MAPPING_EVENT(fuse_iomap_write_map);
+
+TRACE_EVENT(fuse_iomap_end,
+	TP_PROTO(const struct inode *inode,
+		 const struct fuse_iomap_end_in *inarg),
+
+	TP_ARGS(inode, inarg),
+
+	TP_STRUCT__entry(
+		FUSE_IOMAP_OP_FIELDS()
+		__field(size_t,			written)
+		FUSE_IOMAP_MAP_FIELDS(map)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->opflags	=	inarg->opflags;
+		__entry->written	=	inarg->written;
+		__entry->offset		=	inarg->pos;
+		__entry->length		=	inarg->count;
+
+		__entry->mapoffset	=	inarg->map.offset;
+		__entry->maplength	=	inarg->map.length;
+		__entry->mapdev		=	inarg->map.dev;
+		__entry->mapaddr	=	inarg->map.addr;
+		__entry->maptype	=	inarg->map.type;
+		__entry->mapflags	=	inarg->map.flags;
+	),
+
+	TP_printk(FUSE_IOMAP_OP_FMT() " written %zd" FUSE_IOMAP_MAP_FMT(),
+		  FUSE_IOMAP_OP_PRINTK_ARGS(),
+		  __entry->written,
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map))
+);
+
+TRACE_EVENT(fuse_iomap_end_error,
+	TP_PROTO(const struct inode *inode,
+		 const struct fuse_iomap_end_in *inarg, int error),
+
+	TP_ARGS(inode, inarg, error),
+
+	TP_STRUCT__entry(
+		FUSE_IOMAP_OP_FIELDS()
+		__field(size_t,			written)
+		__field(int,			error)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	inarg->pos;
+		__entry->length		=	inarg->count;
+		__entry->opflags	=	inarg->opflags;
+		__entry->written	=	inarg->written;
+		__entry->error		=	error;
+	),
+
+	TP_printk(FUSE_IOMAP_OP_FMT() " written %zd error %d",
+		  FUSE_IOMAP_OP_PRINTK_ARGS(),
+		  __entry->written,
+		  __entry->error)
+);
+#endif /* CONFIG_FUSE_IOMAP */
+
 #endif /* _TRACE_FUSE_H */
 
 #undef TRACE_INCLUDE_PATH
diff --git a/fs/fuse/iomap_priv.h b/fs/fuse/iomap_priv.h
index 243d92cb625095..ca8544a95a4267 100644
--- a/fs/fuse/iomap_priv.h
+++ b/fs/fuse/iomap_priv.h
@@ -10,16 +10,22 @@
 #if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
 # define ASSERT(condition) do {						\
 	int __cond = !!(condition);					\
+	if (unlikely(!__cond))						\
+		trace_fuse_iomap_assert(__func__, __LINE__, #condition); \
 	WARN(!__cond, "Assertion failed: %s, func: %s, line: %d", #condition, __func__, __LINE__); \
 } while (0)
 # define BAD_DATA(condition) ({						\
 	int __cond = !!(condition);					\
+	if (unlikely(__cond))						\
+		trace_fuse_iomap_bad_data(__func__, __LINE__, #condition); \
 	WARN(__cond, "Bad mapping: %s, func: %s, line: %d", #condition, __func__, __LINE__); \
 })
 #else
 # define ASSERT(condition)
 # define BAD_DATA(condition) ({						\
 	int __cond = !!(condition);					\
+	if (unlikely(__cond))						\
+		trace_fuse_iomap_bad_data(__func__, __LINE__, #condition); \
 	unlikely(__cond);						\
 })
 #endif /* CONFIG_FUSE_IOMAP_DEBUG */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index dda757768d3ea6..e503bb06fe0c69 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -327,6 +327,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 	FUSE_ARGS(args);
 	int err;
 
+	trace_fuse_iomap_begin(inode, pos, count, opflags);
+
 	args.opcode = FUSE_IOMAP_BEGIN;
 	args.nodeid = get_node_id(inode);
 	args.in_numargs = 1;
@@ -336,8 +338,13 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
 	err = fuse_simple_request(fm, &args);
-	if (err)
+	if (err) {
+		trace_fuse_iomap_begin_error(inode, pos, count, opflags, err);
 		return err;
+	}
+
+	trace_fuse_iomap_read_map(inode, &outarg.read);
+	trace_fuse_iomap_write_map(inode, &outarg.write);
 
 	err = fuse_iomap_begin_validate(inode, opflags, pos, &outarg);
 	if (err)
@@ -404,6 +411,8 @@ static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t count,
 
 		fuse_iomap_to_server(&inarg.map, iomap);
 
+		trace_fuse_iomap_end(inode, &inarg);
+
 		args.opcode = FUSE_IOMAP_END;
 		args.nodeid = get_node_id(inode);
 		args.in_numargs = 1;
@@ -421,6 +430,7 @@ static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t count,
 		case 0:
 			break;
 		default:
+			trace_fuse_iomap_end_error(inode, &inarg, err);
 			break;
 		}
 	}

[PATCH 03/28] fuse: make debugging configurable at runtime

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Use static keys so that we can configure debugging assertions and dmesg
warnings at runtime.  By default this is turned off so the cost is
merely scanning a nop sled.  However, fuse server developers can turn
it on for their debugging systems.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h     |    8 +++++
 fs/fuse/iomap_priv.h |   16 ++++++++--
 fs/fuse/Kconfig      |   15 +++++++++
 fs/fuse/file_iomap.c |   81 ++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/inode.c      |    7 ++++
 5 files changed, 124 insertions(+), 3 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index f0d408a6e12c32..389b123f0bf144 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1689,6 +1689,14 @@ extern void fuse_sysctl_unregister(void);
 #define fuse_sysctl_unregister()	do { } while (0)
 #endif /* CONFIG_SYSCTL */
 
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
+int fuse_iomap_sysfs_init(struct kobject *kobj);
+void fuse_iomap_sysfs_cleanup(struct kobject *kobj);
+#else
+# define fuse_iomap_sysfs_init(...)		(0)
+# define fuse_iomap_sysfs_cleanup(...)		((void)0)
+#endif
+
 #if IS_ENABLED(CONFIG_FUSE_IOMAP)
 bool fuse_iomap_enabled(void);
 
diff --git a/fs/fuse/iomap_priv.h b/fs/fuse/iomap_priv.h
index ca8544a95a4267..7002eb38f87fe1 100644
--- a/fs/fuse/iomap_priv.h
+++ b/fs/fuse/iomap_priv.h
@@ -6,19 +6,29 @@
 #ifndef _FS_FUSE_IOMAP_PRIV_H
 #define _FS_FUSE_IOMAP_PRIV_H
 
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG_DEFAULT)
+DECLARE_STATIC_KEY_TRUE(fuse_iomap_debug);
+#else
+DECLARE_STATIC_KEY_FALSE(fuse_iomap_debug);
+#endif
+
 #if IS_ENABLED(CONFIG_FUSE_IOMAP)
 #if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
-# define ASSERT(condition) do {						\
+# define ASSERT(condition) \
+while (static_branch_unlikely(&fuse_iomap_debug)) {			\
 	int __cond = !!(condition);					\
 	if (unlikely(!__cond))						\
 		trace_fuse_iomap_assert(__func__, __LINE__, #condition); \
 	WARN(!__cond, "Assertion failed: %s, func: %s, line: %d", #condition, __func__, __LINE__); \
-} while (0)
+	break;								\
+}
 # define BAD_DATA(condition) ({						\
 	int __cond = !!(condition);					\
 	if (unlikely(__cond))						\
 		trace_fuse_iomap_bad_data(__func__, __LINE__, #condition); \
-	WARN(__cond, "Bad mapping: %s, func: %s, line: %d", #condition, __func__, __LINE__); \
+	if (static_branch_unlikely(&fuse_iomap_debug))			\
+		WARN(__cond, "Bad mapping: %s, func: %s, line: %d", #condition, __func__, __LINE__); \
+	unlikely(__cond);								\
 })
 #else
 # define ASSERT(condition)
diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
index 67dfe300bf2e07..52e1a04183e760 100644
--- a/fs/fuse/Kconfig
+++ b/fs/fuse/Kconfig
@@ -101,6 +101,21 @@ config FUSE_IOMAP_DEBUG
 	  Enable debugging assertions for the fuse iomap code paths and logging
 	  of bad iomap file mapping data being sent to the kernel.
 
+	  Say N here if you don't want any debugging code code compiled in at
+	  all.
+
+config FUSE_IOMAP_DEBUG_BY_DEFAULT
+	bool "Debug FUSE file IO over iomap at boot time"
+	default n
+	depends on FUSE_IOMAP_DEBUG
+	help
+	  At boot time, enable debugging assertions for the fuse iomap code
+	  paths and warnings about bad iomap file mapping data.  This enables
+	  fuse server authors to control debugging at runtime even on a
+	  distribution kernel while avoiding most of the overhead on production
+	  systems.  The setting can be changed at runtime via
+	  /sys/fs/fuse/iomap/debug.
+
 config FUSE_IO_URING
 	bool "FUSE communication over io-uring"
 	default y
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index e503bb06fe0c69..e7d19e2aee4541 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -8,6 +8,12 @@
 #include "fuse_trace.h"
 #include "iomap_priv.h"
 
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG_DEFAULT)
+DEFINE_STATIC_KEY_TRUE(fuse_iomap_debug);
+#else
+DEFINE_STATIC_KEY_FALSE(fuse_iomap_debug);
+#endif
+
 static bool __read_mostly enable_iomap =
 #if IS_ENABLED(CONFIG_FUSE_IOMAP_BY_DEFAULT)
 	true;
@@ -17,6 +23,81 @@ static bool __read_mostly enable_iomap =
 module_param(enable_iomap, bool, 0644);
 MODULE_PARM_DESC(enable_iomap, "Enable file I/O through iomap");
 
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
+static struct kobject *iomap_kobj;
+
+static ssize_t fuse_iomap_debug_show(struct kobject *kobject,
+				     struct kobj_attribute *a, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", !!static_key_enabled(&fuse_iomap_debug));
+}
+
+static ssize_t fuse_iomap_debug_store(struct kobject *kobject,
+				      struct kobj_attribute *a,
+				      const char *buf, size_t count)
+{
+	int ret;
+	int val;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	if (val < 0 || val > 1)
+		return -EINVAL;
+
+	if (val)
+		static_branch_enable(&fuse_iomap_debug);
+	else
+		static_branch_disable(&fuse_iomap_debug);
+
+	return count;
+}
+
+#define __INIT_KOBJ_ATTR(_name, _mode, _show, _store)			\
+{									\
+	.attr	= { .name = __stringify(_name), .mode = _mode },	\
+	.show	= _show,						\
+	.store	= _store,						\
+}
+
+#define FUSE_ATTR_RW(_name, _show, _store)			\
+	static struct kobj_attribute fuse_attr_##_name =	\
+			__INIT_KOBJ_ATTR(_name, 0644, _show, _store)
+
+#define FUSE_ATTR_PTR(_name)					\
+	(&fuse_attr_##_name.attr)
+
+FUSE_ATTR_RW(debug, fuse_iomap_debug_show, fuse_iomap_debug_store);
+
+static const struct attribute *fuse_iomap_attrs[] = {
+	FUSE_ATTR_PTR(debug),
+	NULL,
+};
+
+int fuse_iomap_sysfs_init(struct kobject *fuse_kobj)
+{
+	int error;
+
+	iomap_kobj = kobject_create_and_add("iomap", fuse_kobj);
+	if (!iomap_kobj)
+		return -ENOMEM;
+
+	error = sysfs_create_files(iomap_kobj, fuse_iomap_attrs);
+	if (error) {
+		kobject_put(iomap_kobj);
+		return error;
+	}
+
+	return 0;
+}
+
+void fuse_iomap_sysfs_cleanup(struct kobject *fuse_kobj)
+{
+	kobject_put(iomap_kobj);
+}
+#endif /* IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG) */
+
 bool fuse_iomap_enabled(void)
 {
 	/* Don't let anyone touch iomap until the end of the patchset. */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 32f4b7c9a20a8a..0d39e1dcec308d 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -2272,8 +2272,14 @@ static int fuse_sysfs_init(void)
 	if (err)
 		goto out_fuse_unregister;
 
+	err = fuse_iomap_sysfs_init(fuse_kobj);
+	if (err)
+		goto out_fuse_connections;
+
 	return 0;
 
+ out_fuse_connections:
+	sysfs_remove_mount_point(fuse_kobj, "connections");
  out_fuse_unregister:
 	kobject_put(fuse_kobj);
  out_err:
@@ -2282,6 +2288,7 @@ static int fuse_sysfs_init(void)
 
 static void fuse_sysfs_cleanup(void)
 {
+	fuse_iomap_sysfs_cleanup(fuse_kobj);
 	sysfs_remove_mount_point(fuse_kobj, "connections");
 	kobject_put(fuse_kobj);
 }

[PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Enable the use of the backing file open/close ioctls so that fuse
servers can register block devices for use with iomap.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |    5 ++
 include/uapi/linux/fuse.h |    3 +
 fs/fuse/Kconfig           |    1 
 fs/fuse/backing.c         |   12 +++++
 fs/fuse/file_iomap.c      |   99 +++++++++++++++++++++++++++++++++++++++++----
 fs/fuse/trace.c           |    1 
 6 files changed, 111 insertions(+), 10 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 389b123f0bf144..791f210c13a876 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -97,12 +97,14 @@ struct fuse_submount_lookup {
 };
 
 struct fuse_conn;
+struct fuse_backing;
 
 /** Operations for subsystems that want to use a backing file */
 struct fuse_backing_ops {
 	int (*may_admin)(struct fuse_conn *fc, uint32_t flags);
 	int (*may_open)(struct fuse_conn *fc, struct file *file);
 	int (*may_close)(struct fuse_conn *fc, struct file *file);
+	int (*post_open)(struct fuse_conn *fc, struct fuse_backing *fb);
 	unsigned int type;
 };
 
@@ -110,6 +112,7 @@ struct fuse_backing_ops {
 struct fuse_backing {
 	struct file *file;
 	struct cred *cred;
+	struct block_device *bdev;
 	const struct fuse_backing_ops *ops;
 
 	/** refcount */
@@ -1704,6 +1707,8 @@ static inline bool fuse_has_iomap(const struct inode *inode)
 {
 	return get_fuse_conn_c(inode)->iomap;
 }
+
+extern const struct fuse_backing_ops fuse_iomap_backing_ops;
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 3634cbe602cd9c..3a367f387795ff 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1124,7 +1124,8 @@ struct fuse_notify_retrieve_in {
 
 #define FUSE_BACKING_TYPE_MASK		(0xFF)
 #define FUSE_BACKING_TYPE_PASSTHROUGH	(0)
-#define FUSE_BACKING_MAX_TYPE		(FUSE_BACKING_TYPE_PASSTHROUGH)
+#define FUSE_BACKING_TYPE_IOMAP		(1)
+#define FUSE_BACKING_MAX_TYPE		(FUSE_BACKING_TYPE_IOMAP)
 
 #define FUSE_BACKING_FLAGS_ALL		(FUSE_BACKING_TYPE_MASK)
 
diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
index 52e1a04183e760..baa38cf0f295ff 100644
--- a/fs/fuse/Kconfig
+++ b/fs/fuse/Kconfig
@@ -75,6 +75,7 @@ config FUSE_IOMAP
 	depends on FUSE_FS
 	depends on BLOCK
 	select FS_IOMAP
+	select FUSE_BACKING
 	help
 	  Enable fuse servers to operate the regular file I/O path through
 	  the fs-iomap library in the kernel.  This enables higher performance
diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 229c101ab46b0e..fc58636ac78eaa 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -89,6 +89,10 @@ fuse_backing_ops_from_map(const struct fuse_backing_map *map)
 #ifdef CONFIG_FUSE_PASSTHROUGH
 	case FUSE_BACKING_TYPE_PASSTHROUGH:
 		return &fuse_passthrough_backing_ops;
+#endif
+#ifdef CONFIG_FUSE_IOMAP
+	case FUSE_BACKING_TYPE_IOMAP:
+		return &fuse_iomap_backing_ops;
 #endif
 	default:
 		break;
@@ -137,8 +141,16 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
 	fb->file = file;
 	fb->cred = prepare_creds();
 	fb->ops = ops;
+	fb->bdev = NULL;
 	refcount_set(&fb->count, 1);
 
+	res = ops->post_open ? ops->post_open(fc, fb) : 0;
+	if (res) {
+		fuse_backing_free(fb);
+		fb = NULL;
+		goto out;
+	}
+
 	res = fuse_backing_id_alloc(fc, fb);
 	if (res < 0) {
 		fuse_backing_free(fb);
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index e7d19e2aee4541..3a4161633add0e 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -319,10 +319,6 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
 		return false;
 	}
 
-	/* XXX: we don't support devices yet */
-	if (BAD_DATA(map->dev != FUSE_IOMAP_DEV_NULL))
-		return false;
-
 	/* No overflows in the device range, if supplied */
 	if (map->addr != FUSE_IOMAP_NULL_ADDR &&
 	    BAD_DATA(check_add_overflow(map->addr, map->length, &end)))
@@ -334,6 +330,7 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
 /* Convert a mapping from the server into something the kernel can use */
 static inline void fuse_iomap_from_server(struct inode *inode,
 					  struct iomap *iomap,
+					  const struct fuse_backing *fb,
 					  const struct fuse_iomap_io *fmap)
 {
 	iomap->addr = fmap->addr;
@@ -341,7 +338,9 @@ static inline void fuse_iomap_from_server(struct inode *inode,
 	iomap->length = fmap->length;
 	iomap->type = fuse_iomap_type_from_server(fmap->type);
 	iomap->flags = fuse_iomap_flags_from_server(fmap->flags);
-	iomap->bdev = inode->i_sb->s_bdev; /* XXX */
+
+	iomap->bdev = fb ? fb->bdev : NULL;
+	iomap->dax_dev = NULL;
 }
 
 /* Convert a mapping from the kernel into something the server can use */
@@ -392,6 +391,27 @@ static inline bool fuse_is_iomap_file_write(unsigned int opflags)
 	return opflags & (IOMAP_WRITE | IOMAP_ZERO | IOMAP_UNSHARE);
 }
 
+static inline struct fuse_backing *
+fuse_iomap_find_dev(struct fuse_conn *fc, const struct fuse_iomap_io *map)
+{
+	struct fuse_backing *ret = NULL;
+
+	if (map->dev != FUSE_IOMAP_DEV_NULL && map->dev < INT_MAX)
+		ret = fuse_backing_lookup(fc, &fuse_iomap_backing_ops,
+					  map->dev);
+
+	switch (map->type) {
+	case FUSE_IOMAP_TYPE_MAPPED:
+	case FUSE_IOMAP_TYPE_UNWRITTEN:
+		/* Mappings backed by space must have a device/addr */
+		if (BAD_DATA(ret == NULL))
+			return ERR_PTR(-EFSCORRUPTED);
+		break;
+	}
+
+	return ret;
+}
+
 static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 			    unsigned opflags, struct iomap *iomap,
 			    struct iomap *srcmap)
@@ -405,6 +425,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 	};
 	struct fuse_iomap_begin_out outarg = { };
 	struct fuse_mount *fm = get_fuse_mount(inode);
+	struct fuse_backing *read_dev = NULL;
+	struct fuse_backing *write_dev = NULL;
 	FUSE_ARGS(args);
 	int err;
 
@@ -431,24 +453,44 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 	if (err)
 		return err;
 
+	read_dev = fuse_iomap_find_dev(fm->fc, &outarg.read);
+	if (IS_ERR(read_dev))
+		return PTR_ERR(read_dev);
+
 	if (fuse_is_iomap_file_write(opflags) &&
 	    outarg.write.type != FUSE_IOMAP_TYPE_PURE_OVERWRITE) {
+		/* open the write device */
+		write_dev = fuse_iomap_find_dev(fm->fc, &outarg.write);
+		if (IS_ERR(write_dev)) {
+			err = PTR_ERR(write_dev);
+			goto out_read_dev;
+		}
+
 		/*
 		 * For an out of place write, we must supply the write mapping
 		 * via @iomap, and the read mapping via @srcmap.
 		 */
-		fuse_iomap_from_server(inode, iomap, &outarg.write);
-		fuse_iomap_from_server(inode, srcmap, &outarg.read);
+		fuse_iomap_from_server(inode, iomap, write_dev, &outarg.write);
+		fuse_iomap_from_server(inode, srcmap, read_dev, &outarg.read);
 	} else {
 		/*
 		 * For everything else (reads, reporting, and pure overwrites),
 		 * we can return the sole mapping through @iomap and leave
 		 * @srcmap unchanged from its default (HOLE).
 		 */
-		fuse_iomap_from_server(inode, iomap, &outarg.read);
+		fuse_iomap_from_server(inode, iomap, read_dev, &outarg.read);
 	}
 
-	return 0;
+	/*
+	 * XXX: if we ever want to support closing devices, we need a way to
+	 * track the fuse_backing refcount all the way through bio endios.
+	 * For now we put the refcount here because you can't remove an iomap
+	 * device until unmount time.
+	 */
+	fuse_backing_put(write_dev);
+out_read_dev:
+	fuse_backing_put(read_dev);
+	return err;
 }
 
 /* Decide if we send FUSE_IOMAP_END to the fuse server */
@@ -523,3 +565,42 @@ const struct iomap_ops fuse_iomap_ops = {
 	.iomap_begin		= fuse_iomap_begin,
 	.iomap_end		= fuse_iomap_end,
 };
+
+static int fuse_iomap_may_admin(struct fuse_conn *fc, unsigned int flags)
+{
+	if (!fc->iomap)
+		return -EPERM;
+
+	if (flags)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int fuse_iomap_may_open(struct fuse_conn *fc, struct file *file)
+{
+	if (!S_ISBLK(file_inode(file)->i_mode))
+		return -ENODEV;
+
+	return 0;
+}
+
+static int fuse_iomap_post_open(struct fuse_conn *fc, struct fuse_backing *fb)
+{
+	fb->bdev = I_BDEV(fb->file->f_mapping->host);
+	return 0;
+}
+
+static int fuse_iomap_may_close(struct fuse_conn *fc, struct file *file)
+{
+	/* We only support closing iomap block devices at unmount */
+	return -EBUSY;
+}
+
+const struct fuse_backing_ops fuse_iomap_backing_ops = {
+	.type = FUSE_BACKING_TYPE_IOMAP,
+	.may_admin = fuse_iomap_may_admin,
+	.may_open = fuse_iomap_may_open,
+	.may_close = fuse_iomap_may_close,
+	.post_open = fuse_iomap_post_open,
+};
diff --git a/fs/fuse/trace.c b/fs/fuse/trace.c
index 93bd72efc98cd0..3b54f639a5423e 100644
--- a/fs/fuse/trace.c
+++ b/fs/fuse/trace.c
@@ -6,6 +6,7 @@
 #include "dev_uring_i.h"
 #include "fuse_i.h"
 #include "fuse_dev_i.h"
+#include "iomap_priv.h"
 
 #include <linux/pagemap.h>
 

[PATCH 05/28] fuse_trace: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Enhance the existing backing file tracepoints to report the subsystem
that's actually using the backing file.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   42 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index ef94f07cbbf2d4..d39029b30e0198 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -175,6 +175,10 @@ TRACE_EVENT(fuse_request_end,
 );
 
 #ifdef CONFIG_FUSE_BACKING
+#define FUSE_BACKING_FLAG_STRINGS \
+	{ FUSE_BACKING_TYPE_PASSTHROUGH,	"pass" }, \
+	{ FUSE_BACKING_TYPE_IOMAP,		"iomap" }
+
 TRACE_EVENT(fuse_backing_class,
 	TP_PROTO(const struct fuse_conn *fc, unsigned int idx,
 		 const struct fuse_backing *fb),
@@ -184,7 +188,9 @@ TRACE_EVENT(fuse_backing_class,
 	TP_STRUCT__entry(
 		__field(dev_t,			connection)
 		__field(unsigned int,		idx)
+		__field(unsigned int,		type)
 		__field(unsigned long,		ino)
+		__field(dev_t,			rdev)
 	),
 
 	TP_fast_assign(
@@ -193,12 +199,19 @@ TRACE_EVENT(fuse_backing_class,
 		__entry->connection	=	fc->dev;
 		__entry->idx		=	idx;
 		__entry->ino		=	inode->i_ino;
+		__entry->type		=	fb->ops->type;
+		if (fb->ops->type == FUSE_BACKING_TYPE_IOMAP)
+			__entry->rdev	=	inode->i_rdev;
+		else
+			__entry->rdev	=	0;
 	),
 
-	TP_printk("connection %u idx %u ino 0x%lx",
+	TP_printk("connection %u idx %u type %s ino 0x%lx rdev %u:%u",
 		  __entry->connection,
 		  __entry->idx,
-		  __entry->ino)
+		  __print_symbolic(__entry->type, FUSE_BACKING_FLAG_STRINGS),
+		  __entry->ino,
+		  MAJOR(__entry->rdev), MINOR(__entry->rdev))
 );
 #define DEFINE_FUSE_BACKING_EVENT(name)		\
 DEFINE_EVENT(fuse_backing_class, name,		\
@@ -210,7 +223,6 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 #endif /* CONFIG_FUSE_BACKING */
 
 #if IS_ENABLED(CONFIG_FUSE_IOMAP)
-
 /* tracepoint boilerplate so we don't have to keep doing this */
 #define FUSE_IOMAP_OPFLAGS_FIELD \
 		__field(unsigned,		opflags)
@@ -452,6 +464,30 @@ TRACE_EVENT(fuse_iomap_end_error,
 		  __entry->written,
 		  __entry->error)
 );
+
+TRACE_EVENT(fuse_iomap_dev_add,
+	TP_PROTO(const struct fuse_conn *fc,
+		 const struct fuse_backing_map *map),
+
+	TP_ARGS(fc, map),
+
+	TP_STRUCT__entry(
+		__field(dev_t,			connection)
+		__field(int,			fd)
+		__field(unsigned int,		flags)
+	),
+
+	TP_fast_assign(
+		__entry->connection	=	fc->dev;
+		__entry->fd		=	map->fd;
+		__entry->flags		=	map->flags;
+	),
+
+	TP_printk("connection %u fd %d flags 0x%x",
+		  __entry->connection,
+		  __entry->fd,
+		  __entry->flags)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */

[PATCH 06/28] fuse: flush events and send FUSE_SYNCFS and FUSE_DESTROY on unmount

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

At unmount time, there are a few things that we need to ask the fuse
server to do.

First, we need to flush queued events to userspace to give the fuse
server a chance to process the events.  This is how we make sure that
the server processes FUSE_RELEASE events before the connection goes
down.

Second, to ensure that all those metadata updates are persisted to disk
before tell the fuse server to destroy itself, send FUSE_SYNCFS after
waiting for the queued events.

Finally, we need to send FUSE_DESTROY to the fuse server so that it
closes the filesystem and the device fds before unmount returns.  That
way, a script that does something like "umount /dev/sda ; e2fsck -fn
/dev/sda" will not fail the e2fsck because the fd closure races with
e2fsck startup.  Obviously, we need to wait for FUSE_SYNCFS.

This is a major behavior change and who knows what might break existing
code, so we hide it behind iomap mode.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h     |    8 ++++++++
 fs/fuse/file_iomap.c |   29 +++++++++++++++++++++++++++++
 fs/fuse/inode.c      |    9 +++++++--
 3 files changed, 44 insertions(+), 2 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 791f210c13a876..3cda9bc6af23fe 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1432,6 +1432,9 @@ int fuse_init_fs_context_submount(struct fs_context *fsc);
  */
 void fuse_conn_destroy(struct fuse_mount *fm);
 
+/* Send the FUSE_DESTROY command. */
+void fuse_send_destroy(struct fuse_mount *fm);
+
 /* Drop the connection and free the fuse mount */
 void fuse_mount_destroy(struct fuse_mount *fm);
 
@@ -1709,9 +1712,14 @@ static inline bool fuse_has_iomap(const struct inode *inode)
 }
 
 extern const struct fuse_backing_ops fuse_iomap_backing_ops;
+
+void fuse_iomap_mount(struct fuse_mount *fm);
+void fuse_iomap_unmount(struct fuse_mount *fm);
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
+# define fuse_iomap_mount(...)			((void)0)
+# define fuse_iomap_unmount(...)		((void)0)
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 3a4161633add0e..75e6f668baa9ef 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -604,3 +604,32 @@ const struct fuse_backing_ops fuse_iomap_backing_ops = {
 	.may_close = fuse_iomap_may_close,
 	.post_open = fuse_iomap_post_open,
 };
+
+void fuse_iomap_mount(struct fuse_mount *fm)
+{
+	struct fuse_conn *fc = fm->fc;
+
+	/*
+	 * Enable syncfs for iomap fuse servers so that we can send a final
+	 * flush at unmount time.  This also means that we can support
+	 * freeze/thaw properly.
+	 */
+	fc->sync_fs = true;
+}
+
+void fuse_iomap_unmount(struct fuse_mount *fm)
+{
+	struct fuse_conn *fc = fm->fc;
+
+	/*
+	 * Flush all pending commands, then issue a syncfs, flush the syncfs,
+	 * and send a destroy command.  This gives the fuse server a chance to
+	 * process all the pending releases, write the last bits of metadata
+	 * changes to disk, and close the iomap block devices before we return
+	 * from the umount call.
+	 */
+	fuse_flush_requests_and_wait(fc);
+	sync_filesystem(fm->sb);
+	fuse_flush_requests_and_wait(fc);
+	fuse_send_destroy(fm);
+}
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 0d39e1dcec308d..7cb1426ca3e767 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -623,7 +623,7 @@ static void fuse_umount_begin(struct super_block *sb)
 		retire_super(sb);
 }
 
-static void fuse_send_destroy(struct fuse_mount *fm)
+void fuse_send_destroy(struct fuse_mount *fm)
 {
 	if (fm->fc->conn_init) {
 		FUSE_ARGS(args);
@@ -1463,6 +1463,9 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
 
 		init_server_timeout(fc, timeout);
 
+		if (fc->iomap)
+			fuse_iomap_mount(fm);
+
 		fm->sb->s_bdi->ra_pages =
 				min(fm->sb->s_bdi->ra_pages, ra_pages);
 		fc->minor = arg->minor;
@@ -2101,7 +2104,9 @@ void fuse_conn_destroy(struct fuse_mount *fm)
 {
 	struct fuse_conn *fc = fm->fc;
 
-	if (fc->destroy) {
+	if (fc->iomap) {
+		fuse_iomap_unmount(fm);
+	} else if (fc->destroy) {
 		/*
 		 * Flush all pending requests (most of which will be
 		 * FUSE_RELEASE) before sending FUSE_DESTROY, because the fuse

[PATCH 07/28] fuse: create a per-inode flag for toggling iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create a per-inode flag to control whether or not this inode actually
uses iomap.  This is required for non-regular files because iomap
doesn't apply there; and enables fuse filesystems to provide some
non-iomap files if desired.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |   15 +++++++++++++++
 include/uapi/linux/fuse.h |    3 +++
 fs/fuse/file.c            |    1 +
 fs/fuse/file_iomap.c      |   32 ++++++++++++++++++++++++++++++++
 fs/fuse/inode.c           |    2 ++
 5 files changed, 53 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 3cda9bc6af23fe..791e868e568cc5 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -250,6 +250,8 @@ enum {
 	FUSE_I_BTIME,
 	/* Wants or already has page cache IO */
 	FUSE_I_CACHE_IO_MODE,
+	/* Use iomap for this inode */
+	FUSE_I_IOMAP,
 };
 
 struct fuse_conn;
@@ -1715,11 +1717,24 @@ extern const struct fuse_backing_ops fuse_iomap_backing_ops;
 
 void fuse_iomap_mount(struct fuse_mount *fm);
 void fuse_iomap_unmount(struct fuse_mount *fm);
+
+void fuse_iomap_init_inode(struct inode *inode, unsigned attr_flags);
+void fuse_iomap_evict_inode(struct inode *inode);
+
+static inline bool fuse_inode_has_iomap(const struct inode *inode)
+{
+	const struct fuse_inode *fi = get_fuse_inode_c(inode);
+
+	return test_bit(FUSE_I_IOMAP, &fi->state);
+}
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
 # define fuse_iomap_mount(...)			((void)0)
 # define fuse_iomap_unmount(...)		((void)0)
+# define fuse_iomap_init_inode(...)		((void)0)
+# define fuse_iomap_evict_inode(...)		((void)0)
+# define fuse_inode_has_iomap(...)		(false)
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 3a367f387795ff..cc4bca2941cb79 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -238,6 +238,7 @@
  *
  *  7.99
  *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
+ *  - add FUSE_ATTR_IOMAP to enable iomap for specific inodes
  */
 
 #ifndef _LINUX_FUSE_H
@@ -578,9 +579,11 @@ struct fuse_file_lock {
  *
  * FUSE_ATTR_SUBMOUNT: Object is a submount root
  * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
+ * FUSE_ATTR_IOMAP: Use iomap for this inode
  */
 #define FUSE_ATTR_SUBMOUNT      (1 << 0)
 #define FUSE_ATTR_DAX		(1 << 1)
+#define FUSE_ATTR_IOMAP		(1 << 2)
 
 /**
  * Open flags
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ebdca39b2261d7..8982e0b9661bb1 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3127,4 +3127,5 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags)
 
 	if (IS_ENABLED(CONFIG_FUSE_DAX))
 		fuse_dax_inode_init(inode, flags);
+	fuse_iomap_init_inode(inode, flags);
 }
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 75e6f668baa9ef..6ffa5710a92ad5 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -633,3 +633,35 @@ void fuse_iomap_unmount(struct fuse_mount *fm)
 	fuse_flush_requests_and_wait(fc);
 	fuse_send_destroy(fm);
 }
+
+static inline void fuse_inode_set_iomap(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	ASSERT(fuse_has_iomap(inode));
+
+	set_bit(FUSE_I_IOMAP, &fi->state);
+}
+
+static inline void fuse_inode_clear_iomap(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	ASSERT(fuse_has_iomap(inode));
+
+	clear_bit(FUSE_I_IOMAP, &fi->state);
+}
+
+void fuse_iomap_init_inode(struct inode *inode, unsigned attr_flags)
+{
+	struct fuse_conn *conn = get_fuse_conn(inode);
+
+	if (conn->iomap && (attr_flags & FUSE_ATTR_IOMAP))
+		fuse_inode_set_iomap(inode);
+}
+
+void fuse_iomap_evict_inode(struct inode *inode)
+{
+	if (fuse_inode_has_iomap(inode))
+		fuse_inode_clear_iomap(inode);
+}
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 7cb1426ca3e767..b209db07e60e33 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -199,6 +199,8 @@ static void fuse_evict_inode(struct inode *inode)
 		WARN_ON(!list_empty(&fi->write_files));
 		WARN_ON(!list_empty(&fi->queued_writes));
 	}
+
+	fuse_iomap_evict_inode(inode);
 }
 
 static int fuse_reconfigure(struct fs_context *fsc)

[PATCH 08/28] fuse_trace: create a per-inode flag for toggling iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   42 ++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |    4 ++++
 2 files changed, 46 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index d39029b30e0198..cdedaf2b2a0ad5 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -300,6 +300,23 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 	{ FUSE_IOMAP_TYPE_UNWRITTEN,		"unwritten" }, \
 	{ FUSE_IOMAP_TYPE_INLINE,		"inline" }
 
+TRACE_DEFINE_ENUM(FUSE_I_ADVISE_RDPLUS);
+TRACE_DEFINE_ENUM(FUSE_I_INIT_RDPLUS);
+TRACE_DEFINE_ENUM(FUSE_I_SIZE_UNSTABLE);
+TRACE_DEFINE_ENUM(FUSE_I_BAD);
+TRACE_DEFINE_ENUM(FUSE_I_BTIME);
+TRACE_DEFINE_ENUM(FUSE_I_CACHE_IO_MODE);
+TRACE_DEFINE_ENUM(FUSE_I_IOMAP);
+
+#define FUSE_IFLAG_STRINGS \
+	{ 1 << FUSE_I_ADVISE_RDPLUS,		"advise_rdplus" }, \
+	{ 1 << FUSE_I_INIT_RDPLUS,		"init_rdplus" }, \
+	{ 1 << FUSE_I_SIZE_UNSTABLE,		"size_unstable" }, \
+	{ 1 << FUSE_I_BAD,			"bad" }, \
+	{ 1 << FUSE_I_BTIME,			"btime" }, \
+	{ 1 << FUSE_I_CACHE_IO_MODE,		"cacheio" }, \
+	{ 1 << FUSE_I_IOMAP,			"iomap" }
+
 DECLARE_EVENT_CLASS(fuse_iomap_check_class,
 	TP_PROTO(const char *func, int line, const char *condition),
 
@@ -488,6 +505,31 @@ TRACE_EVENT(fuse_iomap_dev_add,
 		  __entry->fd,
 		  __entry->flags)
 );
+
+DECLARE_EVENT_CLASS(fuse_inode_state_class,
+	TP_PROTO(const struct inode *inode),
+	TP_ARGS(inode),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		__field(unsigned long,		state)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->state		=	fi->state;
+	),
+
+	TP_printk(FUSE_INODE_FMT " state (%s)",
+		  FUSE_INODE_PRINTK_ARGS,
+		  __print_flags(__entry->state, "|", FUSE_IFLAG_STRINGS))
+);
+#define DEFINE_FUSE_INODE_STATE_EVENT(name)	\
+DEFINE_EVENT(fuse_inode_state_class, name,	\
+	TP_PROTO(const struct inode *inode),	\
+	TP_ARGS(inode))
+DEFINE_FUSE_INODE_STATE_EVENT(fuse_iomap_init_inode);
+DEFINE_FUSE_INODE_STATE_EVENT(fuse_iomap_evict_inode);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 6ffa5710a92ad5..0759704847598b 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -658,10 +658,14 @@ void fuse_iomap_init_inode(struct inode *inode, unsigned attr_flags)
 
 	if (conn->iomap && (attr_flags & FUSE_ATTR_IOMAP))
 		fuse_inode_set_iomap(inode);
+
+	trace_fuse_iomap_init_inode(inode);
 }
 
 void fuse_iomap_evict_inode(struct inode *inode)
 {
+	trace_fuse_iomap_evict_inode(inode);
+
 	if (fuse_inode_has_iomap(inode))
 		fuse_inode_clear_iomap(inode);
 }

[PATCH 09/28] fuse: isolate the other regular file IO paths from iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

iomap completely takes over all regular file IO, so we don't need to
access any of the other mechanisms at all.  Gate them off so that we can
eventually overlay them with a union to save space in struct fuse_inode.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/dir.c    |   14 +++++++++-----
 fs/fuse/file.c   |   18 +++++++++++++-----
 fs/fuse/inode.c  |    3 ++-
 fs/fuse/iomode.c |    2 +-
 4 files changed, 25 insertions(+), 12 deletions(-)


diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index b116e42431ee12..6dbce975dc96b7 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1998,6 +1998,7 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	FUSE_ARGS(args);
 	struct fuse_setattr_in inarg;
 	struct fuse_attr_out outarg;
+	const bool is_iomap = fuse_inode_has_iomap(inode);
 	bool is_truncate = false;
 	bool is_wb = fc->writeback_cache && S_ISREG(inode->i_mode);
 	loff_t oldsize;
@@ -2055,12 +2056,15 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		if (err)
 			return err;
 
-		fuse_set_nowrite(inode);
-		fuse_release_nowrite(inode);
+		if (!is_iomap) {
+			fuse_set_nowrite(inode);
+			fuse_release_nowrite(inode);
+		}
 	}
 
 	if (is_truncate) {
-		fuse_set_nowrite(inode);
+		if (!is_iomap)
+			fuse_set_nowrite(inode);
 		set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
 		if (trust_local_cmtime && attr->ia_size != inode->i_size)
 			attr->ia_valid |= ATTR_MTIME | ATTR_CTIME;
@@ -2132,7 +2136,7 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	if (!is_wb || is_truncate)
 		i_size_write(inode, outarg.attr.size);
 
-	if (is_truncate) {
+	if (is_truncate && !is_iomap) {
 		/* NOTE: this may release/reacquire fi->lock */
 		__fuse_release_nowrite(inode);
 	}
@@ -2156,7 +2160,7 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	return 0;
 
 error:
-	if (is_truncate)
+	if (is_truncate && !is_iomap)
 		fuse_release_nowrite(inode);
 
 	clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 8982e0b9661bb1..0f253837b57fdc 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -238,6 +238,7 @@ static int fuse_open(struct inode *inode, struct file *file)
 	struct fuse_conn *fc = fm->fc;
 	struct fuse_file *ff;
 	int err;
+	const bool is_iomap = fuse_inode_has_iomap(inode);
 	bool is_truncate = (file->f_flags & O_TRUNC) && fc->atomic_o_trunc;
 	bool is_wb_truncate = is_truncate && fc->writeback_cache;
 	bool dax_truncate = is_truncate && FUSE_IS_DAX(inode);
@@ -259,7 +260,7 @@ static int fuse_open(struct inode *inode, struct file *file)
 			goto out_inode_unlock;
 	}
 
-	if (is_wb_truncate || dax_truncate)
+	if ((is_wb_truncate || dax_truncate) && !is_iomap)
 		fuse_set_nowrite(inode);
 
 	err = fuse_do_open(fm, get_node_id(inode), file, false);
@@ -272,7 +273,7 @@ static int fuse_open(struct inode *inode, struct file *file)
 			fuse_truncate_update_attr(inode, file);
 	}
 
-	if (is_wb_truncate || dax_truncate)
+	if ((is_wb_truncate || dax_truncate) && !is_iomap)
 		fuse_release_nowrite(inode);
 	if (!err) {
 		if (is_truncate)
@@ -520,12 +521,14 @@ static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 {
 	struct inode *inode = file->f_mapping->host;
 	struct fuse_conn *fc = get_fuse_conn(inode);
+	const bool need_sync_writes = !fuse_inode_has_iomap(inode);
 	int err;
 
 	if (fuse_is_bad(inode))
 		return -EIO;
 
-	inode_lock(inode);
+	if (need_sync_writes)
+		inode_lock(inode);
 
 	/*
 	 * Start writeback against all dirty pages of the inode, then
@@ -536,7 +539,8 @@ static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 	if (err)
 		goto out;
 
-	fuse_sync_writes(inode);
+	if (need_sync_writes)
+		fuse_sync_writes(inode);
 
 	/*
 	 * Due to implementation of fuse writeback
@@ -560,7 +564,8 @@ static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 		err = 0;
 	}
 out:
-	inode_unlock(inode);
+	if (need_sync_writes)
+		inode_unlock(inode);
 
 	return err;
 }
@@ -1949,6 +1954,9 @@ static struct fuse_file *__fuse_write_file_get(struct fuse_inode *fi)
 {
 	struct fuse_file *ff;
 
+	if (fuse_inode_has_iomap(&fi->inode))
+		return NULL;
+
 	spin_lock(&fi->lock);
 	ff = list_first_entry_or_null(&fi->write_files, struct fuse_file,
 				      write_entry);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index b209db07e60e33..4f348fc575a5c3 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -194,7 +194,8 @@ static void fuse_evict_inode(struct inode *inode)
 		if (inode->i_nlink > 0)
 			atomic64_inc(&fc->evict_ctr);
 	}
-	if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode)) {
+	if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode) &&
+	    !fuse_inode_has_iomap(inode)) {
 		WARN_ON(fi->iocachectr != 0);
 		WARN_ON(!list_empty(&fi->write_files));
 		WARN_ON(!list_empty(&fi->queued_writes));
diff --git a/fs/fuse/iomode.c b/fs/fuse/iomode.c
index c99e285f3183ef..92225dfa6e7ad9 100644
--- a/fs/fuse/iomode.c
+++ b/fs/fuse/iomode.c
@@ -204,7 +204,7 @@ int fuse_file_io_open(struct file *file, struct inode *inode)
 	 * io modes are not relevant with DAX and with server that does not
 	 * implement open.
 	 */
-	if (FUSE_IS_DAX(inode) || !ff->args)
+	if (fuse_inode_has_iomap(inode) || FUSE_IS_DAX(inode) || !ff->args)
 		return 0;
 
 	/*

[PATCH 10/28] fuse: implement basic iomap reporting such as FIEMAP and SEEK_{DATA,HOLE}

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Implement the basic file mapping reporting functions like FIEMAP, BMAP,
and SEEK_DATA/HOLE.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h     |    8 ++++++
 fs/fuse/dir.c        |    1 +
 fs/fuse/file.c       |   13 ++++++++++
 fs/fuse/file_iomap.c |   68 +++++++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 89 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 791e868e568cc5..ea879b45e904c5 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1727,6 +1727,11 @@ static inline bool fuse_inode_has_iomap(const struct inode *inode)
 
 	return test_bit(FUSE_I_IOMAP, &fi->state);
 }
+
+int fuse_iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+		      u64 start, u64 length);
+loff_t fuse_iomap_lseek(struct file *file, loff_t offset, int whence);
+sector_t fuse_iomap_bmap(struct address_space *mapping, sector_t block);
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
@@ -1735,6 +1740,9 @@ static inline bool fuse_inode_has_iomap(const struct inode *inode)
 # define fuse_iomap_init_inode(...)		((void)0)
 # define fuse_iomap_evict_inode(...)		((void)0)
 # define fuse_inode_has_iomap(...)		(false)
+# define fuse_iomap_fiemap			NULL
+# define fuse_iomap_lseek(...)			(-ENOSYS)
+# define fuse_iomap_bmap(...)			(-ENOSYS)
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 6dbce975dc96b7..467ea2f46798ba 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -2303,6 +2303,7 @@ static const struct inode_operations fuse_common_inode_operations = {
 	.set_acl	= fuse_set_acl,
 	.fileattr_get	= fuse_fileattr_get,
 	.fileattr_set	= fuse_fileattr_set,
+	.fiemap		= fuse_iomap_fiemap,
 };
 
 static const struct inode_operations fuse_symlink_inode_operations = {
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 0f253837b57fdc..1941dd7846f12a 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2522,6 +2522,12 @@ static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
 	struct fuse_bmap_out outarg;
 	int err;
 
+	if (fuse_inode_has_iomap(inode)) {
+		sector_t alt_sec = fuse_iomap_bmap(mapping, block);
+		if (alt_sec > 0)
+			return alt_sec;
+	}
+
 	if (!inode->i_sb->s_bdev || fm->fc->no_bmap)
 		return 0;
 
@@ -2557,6 +2563,13 @@ static loff_t fuse_lseek(struct file *file, loff_t offset, int whence)
 	struct fuse_lseek_out outarg;
 	int err;
 
+	if (fuse_inode_has_iomap(inode)) {
+		loff_t alt_pos = fuse_iomap_lseek(file, offset, whence);
+
+		if (alt_pos >= 0 || (alt_pos < 0 && alt_pos != -ENOSYS))
+			return alt_pos;
+	}
+
 	if (fm->fc->no_lseek)
 		goto fallback;
 
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 0759704847598b..29603eec939589 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -4,6 +4,7 @@
  * Author: Darrick J. Wong <djwong@kernel.org>
  */
 #include <linux/iomap.h>
+#include <linux/fiemap.h>
 #include "fuse_i.h"
 #include "fuse_trace.h"
 #include "iomap_priv.h"
@@ -561,7 +562,7 @@ static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t count,
 	return err;
 }
 
-const struct iomap_ops fuse_iomap_ops = {
+static const struct iomap_ops fuse_iomap_ops = {
 	.iomap_begin		= fuse_iomap_begin,
 	.iomap_end		= fuse_iomap_end,
 };
@@ -669,3 +670,68 @@ void fuse_iomap_evict_inode(struct inode *inode)
 	if (fuse_inode_has_iomap(inode))
 		fuse_inode_clear_iomap(inode);
 }
+
+int fuse_iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+		      u64 start, u64 count)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	int error;
+
+	/*
+	 * We are called directly from the vfs so we need to check per-inode
+	 * support here explicitly.
+	 */
+	if (!fuse_inode_has_iomap(inode))
+		return -EOPNOTSUPP;
+
+	if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR)
+		return -EOPNOTSUPP;
+
+	if (fuse_is_bad(inode))
+		return -EIO;
+
+	if (!fuse_allow_current_process(fc))
+		return -EACCES;
+
+	inode_lock_shared(inode);
+	error = iomap_fiemap(inode, fieinfo, start, count, &fuse_iomap_ops);
+	inode_unlock_shared(inode);
+
+	return error;
+}
+
+sector_t fuse_iomap_bmap(struct address_space *mapping, sector_t block)
+{
+	ASSERT(fuse_inode_has_iomap(mapping->host));
+
+	return iomap_bmap(mapping, block, &fuse_iomap_ops);
+}
+
+loff_t fuse_iomap_lseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file->f_mapping->host;
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	if (fuse_is_bad(inode))
+		return -EIO;
+
+	if (!fuse_allow_current_process(fc))
+		return -EACCES;
+
+	switch (whence) {
+	case SEEK_HOLE:
+		offset = iomap_seek_hole(inode, offset, &fuse_iomap_ops);
+		break;
+	case SEEK_DATA:
+		offset = iomap_seek_data(inode, offset, &fuse_iomap_ops);
+		break;
+	default:
+		return -ENOSYS;
+	}
+
+	if (offset < 0)
+		return offset;
+	return vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
+}

[PATCH 11/28] fuse_trace: implement basic iomap reporting such as FIEMAP and SEEK_{DATA,HOLE}

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |    4 ++++
 2 files changed, 50 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index cdedaf2b2a0ad5..4fe51be0e65bdc 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -530,6 +530,52 @@ DEFINE_EVENT(fuse_inode_state_class, name,	\
 	TP_ARGS(inode))
 DEFINE_FUSE_INODE_STATE_EVENT(fuse_iomap_init_inode);
 DEFINE_FUSE_INODE_STATE_EVENT(fuse_iomap_evict_inode);
+
+TRACE_EVENT(fuse_iomap_fiemap,
+	TP_PROTO(const struct inode *inode, u64 start, u64 count,
+		unsigned int flags),
+
+	TP_ARGS(inode, start, count, flags),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(unsigned int,		flags)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	start;
+		__entry->length		=	count;
+		__entry->flags		=	flags;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT("fiemap") " flags 0x%x",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __entry->flags)
+);
+
+TRACE_EVENT(fuse_iomap_lseek,
+	TP_PROTO(const struct inode *inode, loff_t offset, int whence),
+
+	TP_ARGS(inode, offset, whence),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		__field(loff_t,			offset)
+		__field(int,			whence)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	offset;
+		__entry->whence		=	whence;
+	),
+
+	TP_printk(FUSE_INODE_FMT " offset 0x%llx whence %d",
+		  FUSE_INODE_PRINTK_ARGS,
+		  __entry->offset,
+		  __entry->whence)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 29603eec939589..88d85d572faf97 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -693,6 +693,8 @@ int fuse_iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	if (!fuse_allow_current_process(fc))
 		return -EACCES;
 
+	trace_fuse_iomap_fiemap(inode, start, count, fieinfo->fi_flags);
+
 	inode_lock_shared(inode);
 	error = iomap_fiemap(inode, fieinfo, start, count, &fuse_iomap_ops);
 	inode_unlock_shared(inode);
@@ -720,6 +722,8 @@ loff_t fuse_iomap_lseek(struct file *file, loff_t offset, int whence)
 	if (!fuse_allow_current_process(fc))
 		return -EACCES;
 
+	trace_fuse_iomap_lseek(inode, offset, whence);
+
 	switch (whence) {
 	case SEEK_HOLE:
 		offset = iomap_seek_hole(inode, offset, &fuse_iomap_ops);

[PATCH 12/28] fuse: implement direct IO with iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Start implementing the fuse-iomap file I/O paths by adding direct I/O
support and all the signalling flags that come with it.  Buffered I/O
is much more complicated, so we leave that to a subsequent patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |   30 +++++
 include/uapi/linux/fuse.h |   22 ++++
 fs/fuse/dir.c             |    7 +
 fs/fuse/file.c            |   16 +++
 fs/fuse/file_iomap.c      |  249 +++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/trace.c           |    1 
 6 files changed, 323 insertions(+), 2 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index ea879b45e904c5..ed0608d84ac76c 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -643,6 +643,16 @@ struct fuse_sync_bucket {
 	struct rcu_head rcu;
 };
 
+#ifdef CONFIG_FUSE_IOMAP
+struct fuse_iomap_conn {
+	/* fuse server doesn't implement iomap_end */
+	unsigned int no_end:1;
+
+	/* fuse server doesn't implement iomap_ioend */
+	unsigned int no_ioend:1;
+};
+#endif
+
 /**
  * A Fuse connection.
  *
@@ -992,6 +1002,11 @@ struct fuse_conn {
 	struct idr backing_files_map;
 #endif
 
+#ifdef CONFIG_FUSE_IOMAP
+	/** iomap information */
+	struct fuse_iomap_conn iomap_conn;
+#endif
+
 #ifdef CONFIG_FUSE_IO_URING
 	/**  uring connection information*/
 	struct fuse_ring *ring;
@@ -1732,6 +1747,17 @@ int fuse_iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		      u64 start, u64 length);
 loff_t fuse_iomap_lseek(struct file *file, loff_t offset, int whence);
 sector_t fuse_iomap_bmap(struct address_space *mapping, sector_t block);
+
+void fuse_iomap_open(struct inode *inode, struct file *file);
+
+static inline bool fuse_want_iomap_directio(const struct kiocb *iocb)
+{
+	return (iocb->ki_flags & IOCB_DIRECT) &&
+		fuse_inode_has_iomap(file_inode(iocb->ki_filp));
+}
+
+ssize_t fuse_iomap_direct_read(struct kiocb *iocb, struct iov_iter *to);
+ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from);
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
@@ -1743,6 +1769,10 @@ sector_t fuse_iomap_bmap(struct address_space *mapping, sector_t block);
 # define fuse_iomap_fiemap			NULL
 # define fuse_iomap_lseek(...)			(-ENOSYS)
 # define fuse_iomap_bmap(...)			(-ENOSYS)
+# define fuse_iomap_open(...)			((void)0)
+# define fuse_want_iomap_directio(...)		(false)
+# define fuse_iomap_direct_read(...)		(-ENOSYS)
+# define fuse_iomap_direct_write(...)		(-ENOSYS)
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index cc4bca2941cb79..4835a40b8af664 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -666,6 +666,7 @@ enum fuse_opcode {
 	FUSE_TMPFILE		= 51,
 	FUSE_STATX		= 52,
 
+	FUSE_IOMAP_IOEND	= 4093,
 	FUSE_IOMAP_BEGIN	= 4094,
 	FUSE_IOMAP_END		= 4095,
 
@@ -1389,4 +1390,25 @@ struct fuse_iomap_end_in {
 	struct fuse_iomap_io	map;
 };
 
+/* out of place write extent */
+#define FUSE_IOMAP_IOEND_SHARED		(1U << 0)
+/* unwritten extent */
+#define FUSE_IOMAP_IOEND_UNWRITTEN	(1U << 1)
+/* don't merge into previous ioend */
+#define FUSE_IOMAP_IOEND_BOUNDARY	(1U << 2)
+/* is direct I/O */
+#define FUSE_IOMAP_IOEND_DIRECT		(1U << 3)
+/* is append ioend */
+#define FUSE_IOMAP_IOEND_APPEND		(1U << 4)
+
+struct fuse_iomap_ioend_in {
+	uint32_t ioendflags;	/* FUSE_IOMAP_IOEND_* */
+	int32_t error;		/* negative errno or 0 */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+	uint64_t pos;		/* file position, in bytes */
+	uint64_t new_addr;	/* disk offset of new mapping, in bytes */
+	uint32_t written;	/* bytes processed */
+	uint32_t reserved1;	/* zero */
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 467ea2f46798ba..e0022eea806fbd 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -712,6 +712,10 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
 	if (err)
 		goto out_acl_release;
 	fuse_dir_changed(dir);
+
+	if (fuse_inode_has_iomap(inode))
+		fuse_iomap_open(inode, file);
+
 	err = generic_file_open(inode, file);
 	if (!err) {
 		file->private_data = ff;
@@ -1750,6 +1754,9 @@ static int fuse_dir_open(struct inode *inode, struct file *file)
 	if (fuse_is_bad(inode))
 		return -EIO;
 
+	if (fuse_inode_has_iomap(inode))
+		fuse_iomap_open(inode, file);
+
 	err = generic_file_open(inode, file);
 	if (err)
 		return err;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 1941dd7846f12a..baf433b4c23e1b 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -246,6 +246,9 @@ static int fuse_open(struct inode *inode, struct file *file)
 	if (fuse_is_bad(inode))
 		return -EIO;
 
+	if (is_iomap)
+		fuse_iomap_open(inode, file);
+
 	err = generic_file_open(inode, file);
 	if (err)
 		return err;
@@ -1754,10 +1757,17 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	struct file *file = iocb->ki_filp;
 	struct fuse_file *ff = file->private_data;
 	struct inode *inode = file_inode(file);
+	ssize_t ret;
 
 	if (fuse_is_bad(inode))
 		return -EIO;
 
+	if (fuse_want_iomap_directio(iocb)) {
+		ret = fuse_iomap_direct_read(iocb, to);
+		if (ret != -ENOSYS)
+			return ret;
+	}
+
 	if (FUSE_IS_DAX(inode))
 		return fuse_dax_read_iter(iocb, to);
 
@@ -1779,6 +1789,12 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (fuse_is_bad(inode))
 		return -EIO;
 
+	if (fuse_want_iomap_directio(iocb)) {
+		ssize_t ret = fuse_iomap_direct_write(iocb, from);
+		if (ret != -ENOSYS)
+			return ret;
+	}
+
 	if (FUSE_IS_DAX(inode))
 		return fuse_dax_write_iter(iocb, from);
 
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 88d85d572faf97..84eb1fe4fcde49 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -495,10 +495,15 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 }
 
 /* Decide if we send FUSE_IOMAP_END to the fuse server */
-static bool fuse_should_send_iomap_end(const struct iomap *iomap,
+static bool fuse_should_send_iomap_end(const struct fuse_mount *fm,
+				       const struct iomap *iomap,
 				       unsigned int opflags, loff_t count,
 				       ssize_t written)
 {
+	/* Not implemented on fuse server */
+	if (fm->fc->iomap_conn.no_end)
+		return false;
+
 	/* fuse server demanded an iomap_end call. */
 	if (iomap->flags & FUSE_IOMAP_F_WANT_IOMAP_END)
 		return true;
@@ -523,7 +528,7 @@ static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t count,
 	struct fuse_mount *fm = get_fuse_mount(inode);
 	int err = 0;
 
-	if (fuse_should_send_iomap_end(iomap, opflags, count, written)) {
+	if (fuse_should_send_iomap_end(fm, iomap, opflags, count, written)) {
 		struct fuse_iomap_end_in inarg = {
 			.opflags = fuse_iomap_op_to_server(opflags),
 			.attr_ino = fi->orig_ino,
@@ -549,6 +554,7 @@ static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t count,
 			 * libfuse returns ENOSYS for servers that don't
 			 * implement iomap_end
 			 */
+			fm->fc->iomap_conn.no_end = 1;
 			err = 0;
 			break;
 		case 0:
@@ -567,6 +573,95 @@ static const struct iomap_ops fuse_iomap_ops = {
 	.iomap_end		= fuse_iomap_end,
 };
 
+static inline bool
+fuse_should_send_iomap_ioend(const struct fuse_mount *fm,
+			     const struct fuse_iomap_ioend_in *inarg)
+{
+	/* Not implemented on fuse server */
+	if (fm->fc->iomap_conn.no_ioend)
+		return false;
+
+	/* Always send an ioend for errors. */
+	if (inarg->error)
+		return true;
+
+	/* Send an ioend if we performed an IO involving metadata changes. */
+	return inarg->written > 0 &&
+	       (inarg->ioendflags & (FUSE_IOMAP_IOEND_SHARED |
+				     FUSE_IOMAP_IOEND_UNWRITTEN |
+				     FUSE_IOMAP_IOEND_APPEND));
+}
+
+/*
+ * Fast and loose check if this write could update the on-disk inode size.
+ */
+static inline bool fuse_ioend_is_append(const struct fuse_inode *fi,
+					loff_t pos, size_t written)
+{
+	return pos + written > i_size_read(&fi->inode);
+}
+
+static int fuse_iomap_ioend(struct inode *inode, loff_t pos, size_t written,
+			    int error, unsigned ioendflags, sector_t new_addr)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_mount *fm = get_fuse_mount(inode);
+	struct fuse_iomap_ioend_in inarg = {
+		.ioendflags = ioendflags,
+		.error = error,
+		.attr_ino = fi->orig_ino,
+		.pos = pos,
+		.written = written,
+		.new_addr = new_addr,
+	};
+
+	if (fuse_ioend_is_append(fi, pos, written))
+		inarg.ioendflags |= FUSE_IOMAP_IOEND_APPEND;
+
+	if (fuse_should_send_iomap_ioend(fm, &inarg)) {
+		FUSE_ARGS(args);
+		int err;
+
+		args.opcode = FUSE_IOMAP_IOEND;
+		args.nodeid = get_node_id(inode);
+		args.in_numargs = 1;
+		args.in_args[0].size = sizeof(inarg);
+		args.in_args[0].value = &inarg;
+		err = fuse_simple_request(fm, &args);
+		switch (err) {
+		case -ENOSYS:
+			/*
+			 * fuse servers can return ENOSYS if ioend processing
+			 * is never needed for this filesystem.
+			 */
+			fm->fc->iomap_conn.no_ioend = 1;
+			err = 0;
+			break;
+		case 0:
+			break;
+		default:
+			/*
+			 * If the write IO failed, return the failure code to
+			 * the caller no matter what happens with the ioend.
+			 * If the write IO succeeded but the ioend did not,
+			 * pass the new error up to the caller.
+			 */
+			if (!error)
+				error = err;
+			break;
+		}
+	}
+	if (error)
+		return error;
+
+	/*
+	 * If there weren't any ioend errors, update the incore isize, which
+	 * confusingly takes the new i_size as "pos".
+	 */
+	fuse_write_update_attr(inode, pos + written, written);
+	return 0;
+}
+
 static int fuse_iomap_may_admin(struct fuse_conn *fc, unsigned int flags)
 {
 	if (!fc->iomap)
@@ -616,6 +711,8 @@ void fuse_iomap_mount(struct fuse_mount *fm)
 	 * freeze/thaw properly.
 	 */
 	fc->sync_fs = true;
+	fc->iomap_conn.no_end = 0;
+	fc->iomap_conn.no_ioend = 0;
 }
 
 void fuse_iomap_unmount(struct fuse_mount *fm)
@@ -739,3 +836,151 @@ loff_t fuse_iomap_lseek(struct file *file, loff_t offset, int whence)
 		return offset;
 	return vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
 }
+
+void fuse_iomap_open(struct inode *inode, struct file *file)
+{
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	file->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
+}
+
+enum fuse_ilock_type {
+	SHARED,
+	EXCL,
+};
+
+static int fuse_iomap_ilock_iocb(const struct kiocb *iocb,
+				 enum fuse_ilock_type type)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		switch (type) {
+		case SHARED:
+			return inode_trylock_shared(inode) ? 0 : -EAGAIN;
+		case EXCL:
+			return inode_trylock(inode) ? 0 : -EAGAIN;
+		default:
+			ASSERT(0);
+			return -EIO;
+		}
+	} else {
+		switch (type) {
+		case SHARED:
+			inode_lock_shared(inode);
+			break;
+		case EXCL:
+			inode_lock(inode);
+			break;
+		default:
+			ASSERT(0);
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+ssize_t fuse_iomap_direct_read(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t ret;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	if (!iov_iter_count(to))
+		return 0; /* skip atime */
+
+	file_accessed(iocb->ki_filp);
+
+	ret = fuse_iomap_ilock_iocb(iocb, SHARED);
+	if (ret)
+		return ret;
+	ret = iomap_dio_rw(iocb, to, &fuse_iomap_ops, NULL, 0, NULL, 0);
+	inode_unlock_shared(inode);
+
+	return ret;
+}
+
+static int fuse_iomap_dio_write_end_io(struct kiocb *iocb, ssize_t written,
+				       int error, unsigned dioflags)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	unsigned int nofs_flag;
+	unsigned int ioendflags = FUSE_IOMAP_IOEND_DIRECT;
+	int ret;
+
+	if (fuse_is_bad(inode))
+		return -EIO;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	if (dioflags & IOMAP_DIO_COW)
+		ioendflags |= FUSE_IOMAP_IOEND_SHARED;
+	if (dioflags & IOMAP_DIO_UNWRITTEN)
+		ioendflags |= FUSE_IOMAP_IOEND_UNWRITTEN;
+
+	/*
+	 * We can allocate memory here while doing writeback on behalf of
+	 * memory reclaim.  To avoid memory allocation deadlocks set the
+	 * task-wide nofs context for the following operations.
+	 */
+	nofs_flag = memalloc_nofs_save();
+	ret = fuse_iomap_ioend(inode, iocb->ki_pos, written, error, ioendflags,
+			       FUSE_IOMAP_NULL_ADDR);
+	memalloc_nofs_restore(nofs_flag);
+	return ret;
+}
+
+static const struct iomap_dio_ops fuse_iomap_dio_write_ops = {
+	.end_io		= fuse_iomap_dio_write_end_io,
+};
+
+ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	loff_t blockmask = i_blocksize(inode) - 1;
+	size_t count = iov_iter_count(from);
+	unsigned int flags = 0;
+	ssize_t ret;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	if (!count)
+		return 0;
+
+	/*
+	 * Unaligned direct writes require zeroing of unwritten head and tail
+	 * blocks.  Extending writes require zeroing of post-EOF tail blocks.
+	 * The zeroing writes must complete before we return the direct write
+	 * to userspace.  Don't even bother trying the fast path.
+	 */
+	if ((iocb->ki_pos | count) & blockmask)
+		flags = IOMAP_DIO_FORCE_WAIT;
+
+	ret = fuse_iomap_ilock_iocb(iocb, EXCL);
+	if (ret)
+		goto out_dsync;
+	ret = generic_write_checks(iocb, from);
+	if (ret <= 0)
+		goto out_unlock;
+
+	/*
+	 * If we are doing exclusive unaligned I/O, this must be the only I/O
+	 * in-flight.  Otherwise we risk data corruption due to unwritten
+	 * extent conversions from the AIO end_io handler.  Wait for all other
+	 * I/O to drain first.
+	 */
+	if (flags & IOMAP_DIO_FORCE_WAIT)
+		inode_dio_wait(inode);
+
+	ret = iomap_dio_rw(iocb, from, &fuse_iomap_ops,
+			   &fuse_iomap_dio_write_ops, flags, NULL, 0);
+	if (ret)
+		goto out_unlock;
+
+out_unlock:
+	inode_unlock(inode);
+out_dsync:
+	return ret;
+}
diff --git a/fs/fuse/trace.c b/fs/fuse/trace.c
index 3b54f639a5423e..9de407148c867d 100644
--- a/fs/fuse/trace.c
+++ b/fs/fuse/trace.c
@@ -9,6 +9,7 @@
 #include "iomap_priv.h"
 
 #include <linux/pagemap.h>
+#include <linux/iomap.h>
 
 #define CREATE_TRACE_POINTS
 #include "fuse_trace.h"

[PATCH 13/28] fuse_trace: implement direct IO with iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |  144 ++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |   13 +++++
 2 files changed, 157 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 4fe51be0e65bdc..434d38ce89c428 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -60,6 +60,7 @@
 	EM( FUSE_STATX,			"FUSE_STATX")		\
 	EM( FUSE_IOMAP_BEGIN,		"FUSE_IOMAP_BEGIN")	\
 	EM( FUSE_IOMAP_END,		"FUSE_IOMAP_END")	\
+	EM( FUSE_IOMAP_IOEND,		"FUSE_IOMAP_IOEND")	\
 	EMe(CUSE_INIT,			"CUSE_INIT")
 
 /*
@@ -300,6 +301,17 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 	{ FUSE_IOMAP_TYPE_UNWRITTEN,		"unwritten" }, \
 	{ FUSE_IOMAP_TYPE_INLINE,		"inline" }
 
+#define FUSE_IOMAP_IOEND_STRINGS \
+	{ FUSE_IOMAP_IOEND_SHARED,		"shared" }, \
+	{ FUSE_IOMAP_IOEND_UNWRITTEN,		"unwritten" }, \
+	{ FUSE_IOMAP_IOEND_BOUNDARY,		"boundary" }, \
+	{ FUSE_IOMAP_IOEND_DIRECT,		"direct" }, \
+	{ FUSE_IOMAP_IOEND_APPEND,		"append" }
+
+#define IOMAP_DIOEND_STRINGS \
+	{ IOMAP_DIO_UNWRITTEN,			"unwritten" }, \
+	{ IOMAP_DIO_COW,			"cow" }
+
 TRACE_DEFINE_ENUM(FUSE_I_ADVISE_RDPLUS);
 TRACE_DEFINE_ENUM(FUSE_I_INIT_RDPLUS);
 TRACE_DEFINE_ENUM(FUSE_I_SIZE_UNSTABLE);
@@ -482,6 +494,65 @@ TRACE_EVENT(fuse_iomap_end_error,
 		  __entry->error)
 );
 
+TRACE_EVENT(fuse_iomap_ioend,
+	TP_PROTO(const struct inode *inode,
+		 const struct fuse_iomap_ioend_in *inarg),
+
+	TP_ARGS(inode, inarg),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(unsigned,		ioendflags)
+		__field(int,			error)
+		__field(uint64_t,		new_addr)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	inarg->pos;
+		__entry->length		=	inarg->written;
+		__entry->ioendflags	=	inarg->ioendflags;
+		__entry->error		=	inarg->error;
+		__entry->new_addr	=	inarg->new_addr;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() " ioendflags (%s) error %d new_addr 0x%llx",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __print_flags(__entry->ioendflags, "|", FUSE_IOMAP_IOEND_STRINGS),
+		  __entry->error,
+		  __entry->new_addr)
+);
+
+TRACE_EVENT(fuse_iomap_ioend_error,
+	TP_PROTO(const struct inode *inode,
+		 const struct fuse_iomap_ioend_in *inarg,
+		 int error),
+
+	TP_ARGS(inode, inarg, error),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(unsigned,		ioendflags)
+		__field(int,			error)
+		__field(uint64_t,		new_addr)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	inarg->pos;
+		__entry->length		=	inarg->written;
+		__entry->ioendflags	=	inarg->ioendflags;
+		__entry->error		=	error;
+		__entry->new_addr	=	inarg->new_addr;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() " ioendflags (%s) error %d new_addr 0x%llx",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __print_flags(__entry->ioendflags, "|", FUSE_IOMAP_IOEND_STRINGS),
+		  __entry->error,
+		  __entry->new_addr)
+);
+
 TRACE_EVENT(fuse_iomap_dev_add,
 	TP_PROTO(const struct fuse_conn *fc,
 		 const struct fuse_backing_map *map),
@@ -576,6 +647,79 @@ TRACE_EVENT(fuse_iomap_lseek,
 		  __entry->offset,
 		  __entry->whence)
 );
+
+DECLARE_EVENT_CLASS(fuse_iomap_file_io_class,
+	TP_PROTO(const struct kiocb *iocb, const struct iov_iter *iter),
+	TP_ARGS(iocb, iter),
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+	),
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(file_inode(iocb->ki_filp), fi, fm);
+		__entry->offset		=	iocb->ki_pos;
+		__entry->length		=	iov_iter_count(iter);
+	),
+	TP_printk(FUSE_IO_RANGE_FMT(),
+		  FUSE_IO_RANGE_PRINTK_ARGS())
+)
+#define DEFINE_FUSE_IOMAP_FILE_IO_EVENT(name)		\
+DEFINE_EVENT(fuse_iomap_file_io_class, name,		\
+	TP_PROTO(const struct kiocb *iocb, const struct iov_iter *iter), \
+	TP_ARGS(iocb, iter))
+DEFINE_FUSE_IOMAP_FILE_IO_EVENT(fuse_iomap_direct_read);
+DEFINE_FUSE_IOMAP_FILE_IO_EVENT(fuse_iomap_direct_write);
+
+DECLARE_EVENT_CLASS(fuse_iomap_file_ioend_class,
+	TP_PROTO(const struct kiocb *iocb, const struct iov_iter *iter,
+		 ssize_t ret),
+	TP_ARGS(iocb, iter, ret),
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(ssize_t,		ret)
+	),
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(file_inode(iocb->ki_filp), fi, fm);
+		__entry->offset		=	iocb->ki_pos;
+		__entry->length		=	iov_iter_count(iter);
+		__entry->ret		=	ret;
+	),
+	TP_printk(FUSE_IO_RANGE_FMT() " ret 0x%zx",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __entry->ret)
+)
+#define DEFINE_FUSE_IOMAP_FILE_IOEND_EVENT(name)	\
+DEFINE_EVENT(fuse_iomap_file_ioend_class, name,		\
+	TP_PROTO(const struct kiocb *iocb, const struct iov_iter *iter, \
+		 ssize_t ret), \
+	TP_ARGS(iocb, iter, ret))
+DEFINE_FUSE_IOMAP_FILE_IOEND_EVENT(fuse_iomap_direct_read_end);
+DEFINE_FUSE_IOMAP_FILE_IOEND_EVENT(fuse_iomap_direct_write_end);
+
+TRACE_EVENT(fuse_iomap_dio_write_end_io,
+	TP_PROTO(const struct inode *inode, loff_t pos, ssize_t written,
+		 int error, unsigned flags),
+
+	TP_ARGS(inode, pos, written, error, flags),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(unsigned,		dioendflags)
+		__field(int,			error)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	pos;
+		__entry->length		=	written;
+		__entry->dioendflags	=	flags;
+		__entry->error		=	error;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() " dioendflags (%s) error %d",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __print_flags(__entry->dioendflags, "|", IOMAP_DIOEND_STRINGS),
+		  __entry->error)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 84eb1fe4fcde49..54e09f60980ef1 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -618,6 +618,8 @@ static int fuse_iomap_ioend(struct inode *inode, loff_t pos, size_t written,
 	if (fuse_ioend_is_append(fi, pos, written))
 		inarg.ioendflags |= FUSE_IOMAP_IOEND_APPEND;
 
+	trace_fuse_iomap_ioend(inode, &inarg);
+
 	if (fuse_should_send_iomap_ioend(fm, &inarg)) {
 		FUSE_ARGS(args);
 		int err;
@@ -640,6 +642,8 @@ static int fuse_iomap_ioend(struct inode *inode, loff_t pos, size_t written,
 		case 0:
 			break;
 		default:
+			trace_fuse_iomap_ioend_error(inode, &inarg, err);
+
 			/*
 			 * If the write IO failed, return the failure code to
 			 * the caller no matter what happens with the ioend.
@@ -888,6 +892,8 @@ ssize_t fuse_iomap_direct_read(struct kiocb *iocb, struct iov_iter *to)
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_direct_read(iocb, to);
+
 	if (!iov_iter_count(to))
 		return 0; /* skip atime */
 
@@ -899,6 +905,7 @@ ssize_t fuse_iomap_direct_read(struct kiocb *iocb, struct iov_iter *to)
 	ret = iomap_dio_rw(iocb, to, &fuse_iomap_ops, NULL, 0, NULL, 0);
 	inode_unlock_shared(inode);
 
+	trace_fuse_iomap_direct_read_end(iocb, to, ret);
 	return ret;
 }
 
@@ -915,6 +922,9 @@ static int fuse_iomap_dio_write_end_io(struct kiocb *iocb, ssize_t written,
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_dio_write_end_io(inode, iocb->ki_pos, written, error,
+					  dioflags);
+
 	if (dioflags & IOMAP_DIO_COW)
 		ioendflags |= FUSE_IOMAP_IOEND_SHARED;
 	if (dioflags & IOMAP_DIO_UNWRITTEN)
@@ -946,6 +956,8 @@ ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from)
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_direct_write(iocb, from);
+
 	if (!count)
 		return 0;
 
@@ -982,5 +994,6 @@ ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from)
 out_unlock:
 	inode_unlock(inode);
 out_dsync:
+	trace_fuse_iomap_direct_write_end(iocb, from, ret);
 	return ret;
 }

[PATCH 14/28] fuse: implement buffered IO with iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Implement pagecache IO with iomap, complete with hooks into truncate and
fallocate so that the fuse server needn't implement disk block zeroing
of post-EOF and unaligned punch/zero regions.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |   30 ++
 include/uapi/linux/fuse.h |    5 
 fs/fuse/dir.c             |   23 ++
 fs/fuse/file.c            |   86 +++++-
 fs/fuse/file_iomap.c      |  659 ++++++++++++++++++++++++++++++++++++++++++++-
 5 files changed, 777 insertions(+), 26 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index ed0608d84ac76c..7581d22de2340c 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -179,6 +179,13 @@ struct fuse_inode {
 
 			/* waitq for direct-io completion */
 			wait_queue_head_t direct_io_waitq;
+
+#ifdef CONFIG_FUSE_IOMAP
+			/* pending io completions */
+			spinlock_t ioend_lock;
+			struct work_struct ioend_work;
+			struct list_head ioend_list;
+#endif
 		};
 
 		/* readdir cache (directory only) */
@@ -1720,6 +1727,8 @@ void fuse_iomap_sysfs_cleanup(struct kobject *kobj);
 # define fuse_iomap_sysfs_cleanup(...)		((void)0)
 #endif
 
+sector_t fuse_bmap(struct address_space *mapping, sector_t block);
+
 #if IS_ENABLED(CONFIG_FUSE_IOMAP)
 bool fuse_iomap_enabled(void);
 
@@ -1758,6 +1767,20 @@ static inline bool fuse_want_iomap_directio(const struct kiocb *iocb)
 
 ssize_t fuse_iomap_direct_read(struct kiocb *iocb, struct iov_iter *to);
 ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from);
+
+static inline bool fuse_want_iomap_buffered_io(const struct kiocb *iocb)
+{
+	return fuse_inode_has_iomap(file_inode(iocb->ki_filp));
+}
+
+int fuse_iomap_mmap(struct file *file, struct vm_area_struct *vma);
+ssize_t fuse_iomap_buffered_read(struct kiocb *iocb, struct iov_iter *to);
+ssize_t fuse_iomap_buffered_write(struct kiocb *iocb, struct iov_iter *from);
+int fuse_iomap_setsize_start(struct inode *inode, loff_t newsize);
+int fuse_iomap_fallocate(struct file *file, int mode, loff_t offset,
+			 loff_t length, loff_t new_size);
+int fuse_iomap_flush_unmap_range(struct inode *inode, loff_t pos,
+				 loff_t endpos);
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
@@ -1773,6 +1796,13 @@ ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from);
 # define fuse_want_iomap_directio(...)		(false)
 # define fuse_iomap_direct_read(...)		(-ENOSYS)
 # define fuse_iomap_direct_write(...)		(-ENOSYS)
+# define fuse_want_iomap_buffered_io(...)	(false)
+# define fuse_iomap_mmap(...)			(-ENOSYS)
+# define fuse_iomap_buffered_read(...)		(-ENOSYS)
+# define fuse_iomap_buffered_write(...)		(-ENOSYS)
+# define fuse_iomap_setsize_start(...)		(-ENOSYS)
+# define fuse_iomap_fallocate(...)		(-ENOSYS)
+# define fuse_iomap_flush_unmap_range(...)	(-ENOSYS)
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 4835a40b8af664..c0af8a4d3e30d8 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1351,6 +1351,9 @@ struct fuse_uring_cmd_req {
 #define FUSE_IOMAP_OP_ATOMIC		(1U << 9)
 #define FUSE_IOMAP_OP_DONTCACHE		(1U << 10)
 
+/* pagecache writeback operation */
+#define FUSE_IOMAP_OP_WRITEBACK		(1U << 31)
+
 #define FUSE_IOMAP_NULL_ADDR		(-1ULL)	/* addr is not valid */
 
 struct fuse_iomap_io {
@@ -1400,6 +1403,8 @@ struct fuse_iomap_end_in {
 #define FUSE_IOMAP_IOEND_DIRECT		(1U << 3)
 /* is append ioend */
 #define FUSE_IOMAP_IOEND_APPEND		(1U << 4)
+/* is pagecache writeback */
+#define FUSE_IOMAP_IOEND_WRITEBACK	(1U << 5)
 
 struct fuse_iomap_ioend_in {
 	uint32_t ioendflags;	/* FUSE_IOMAP_IOEND_* */
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index e0022eea806fbd..d62ceadbc05fb2 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -2027,7 +2027,10 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		is_truncate = true;
 	}
 
-	if (FUSE_IS_DAX(inode) && is_truncate) {
+	if (is_iomap && is_truncate) {
+		filemap_invalidate_lock(mapping);
+		fault_blocked = true;
+	} else if (FUSE_IS_DAX(inode) && is_truncate) {
 		filemap_invalidate_lock(mapping);
 		fault_blocked = true;
 		err = fuse_dax_break_layouts(inode, 0, -1);
@@ -2042,6 +2045,18 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		WARN_ON(!(attr->ia_valid & ATTR_SIZE));
 		WARN_ON(attr->ia_size != 0);
 		if (fc->atomic_o_trunc) {
+			if (is_iomap) {
+				/*
+				 * fuse_open already set the size to zero and
+				 * truncated the pagecache, and we've since
+				 * cycled the inode locks.  Another thread
+				 * could have performed an appending write, so
+				 * we don't want to touch the file further.
+				 */
+				filemap_invalidate_unlock(mapping);
+				return 0;
+			}
+
 			/*
 			 * No need to send request to userspace, since actual
 			 * truncation has already been done by OPEN.  But still
@@ -2075,6 +2090,12 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
 		if (trust_local_cmtime && attr->ia_size != inode->i_size)
 			attr->ia_valid |= ATTR_MTIME | ATTR_CTIME;
+
+		if (is_iomap) {
+			err = fuse_iomap_setsize_start(inode, attr->ia_size);
+			if (err)
+				goto error;
+		}
 	}
 
 	memset(&inarg, 0, sizeof(inarg));
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index baf433b4c23e1b..dd65485c9743bf 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -384,7 +384,7 @@ static int fuse_release(struct inode *inode, struct file *file)
 	 * Dirty pages might remain despite write_inode_now() call from
 	 * fuse_flush() due to writes racing with the close.
 	 */
-	if (fc->writeback_cache)
+	if (fc->writeback_cache || fuse_inode_has_iomap(inode))
 		write_inode_now(inode, 1);
 
 	fuse_release_common(file, false);
@@ -1768,6 +1768,9 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 			return ret;
 	}
 
+	if (fuse_want_iomap_buffered_io(iocb))
+		return fuse_iomap_buffered_read(iocb, to);
+
 	if (FUSE_IS_DAX(inode))
 		return fuse_dax_read_iter(iocb, to);
 
@@ -1791,10 +1794,29 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 	if (fuse_want_iomap_directio(iocb)) {
 		ssize_t ret = fuse_iomap_direct_write(iocb, from);
-		if (ret != -ENOSYS)
+		switch (ret) {
+		case -ENOTBLK:
+			/*
+			 * If we're going to fall back to the iomap buffered
+			 * write path only, then try the write again as a
+			 * synchronous buffered write.  Otherwise we let it
+			 * drop through to the old ->direct_IO path.
+			 */
+			if (fuse_want_iomap_buffered_io(iocb))
+				iocb->ki_flags |= IOCB_SYNC;
+			fallthrough;
+		case -ENOSYS:
+			/* no implementation, fall through */
+			break;
+		default:
+			/* errors, no progress, or even partial progress */
 			return ret;
+		}
 	}
 
+	if (fuse_want_iomap_buffered_io(iocb))
+		return fuse_iomap_buffered_write(iocb, from);
+
 	if (FUSE_IS_DAX(inode))
 		return fuse_dax_write_iter(iocb, from);
 
@@ -2331,6 +2353,9 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 	struct inode *inode = file_inode(file);
 	int rc;
 
+	if (fuse_inode_has_iomap(inode))
+		return fuse_iomap_mmap(file, vma);
+
 	/* DAX mmap is superior to direct_io mmap */
 	if (FUSE_IS_DAX(inode))
 		return fuse_dax_mmap(file, vma);
@@ -2529,7 +2554,7 @@ static int fuse_file_flock(struct file *file, int cmd, struct file_lock *fl)
 	return err;
 }
 
-static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
+sector_t fuse_bmap(struct address_space *mapping, sector_t block)
 {
 	struct inode *inode = mapping->host;
 	struct fuse_mount *fm = get_fuse_mount(inode);
@@ -2883,8 +2908,12 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 
 static int fuse_writeback_range(struct inode *inode, loff_t start, loff_t end)
 {
-	int err = filemap_write_and_wait_range(inode->i_mapping, start, LLONG_MAX);
+	int err;
 
+	if (fuse_inode_has_iomap(inode))
+		return fuse_iomap_flush_unmap_range(inode, start, end);
+
+	err = filemap_write_and_wait_range(inode->i_mapping, start, LLONG_MAX);
 	if (!err)
 		fuse_sync_writes(inode);
 
@@ -2905,7 +2934,9 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 		.length = length,
 		.mode = mode
 	};
+	loff_t newsize = 0;
 	int err;
+	const bool is_iomap = fuse_inode_has_iomap(inode);
 	bool block_faults = FUSE_IS_DAX(inode) &&
 		(!(mode & FALLOC_FL_KEEP_SIZE) ||
 		 (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)));
@@ -2918,7 +2949,10 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 		return -EOPNOTSUPP;
 
 	inode_lock(inode);
-	if (block_faults) {
+	if (is_iomap) {
+		filemap_invalidate_lock(inode->i_mapping);
+		block_faults = true;
+	} else if (block_faults) {
 		filemap_invalidate_lock(inode->i_mapping);
 		err = fuse_dax_break_layouts(inode, 0, -1);
 		if (err)
@@ -2933,11 +2967,23 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 			goto out;
 	}
 
+	/*
+	 * If we are using iomap for file IO, fallocate must wait for all AIO
+	 * to complete before we continue as AIO can change the file size on
+	 * completion without holding any locks we currently hold. We must do
+	 * this first because AIO can update the in-memory inode size, and the
+	 * operations that follow require the in-memory size to be fully
+	 * up-to-date.
+	 */
+	if (is_iomap)
+		inode_dio_wait(inode);
+
 	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
 	    offset + length > i_size_read(inode)) {
 		err = inode_newsize_ok(inode, offset + length);
 		if (err)
 			goto out;
+		newsize = offset + length;
 	}
 
 	err = file_modified(file);
@@ -2960,14 +3006,22 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 	if (err)
 		goto out;
 
-	/* we could have extended the file */
-	if (!(mode & FALLOC_FL_KEEP_SIZE)) {
-		if (fuse_write_update_attr(inode, offset + length, length))
-			file_update_time(file);
-	}
+	if (is_iomap) {
+		err = fuse_iomap_fallocate(file, mode, offset, length,
+					   newsize);
+		if (err)
+			goto out;
+	} else {
+		/* we could have extended the file */
+		if (!(mode & FALLOC_FL_KEEP_SIZE)) {
+			if (fuse_write_update_attr(inode, newsize, length))
+				file_update_time(file);
+		}
 
-	if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
-		truncate_pagecache_range(inode, offset, offset + length - 1);
+		if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
+			truncate_pagecache_range(inode, offset,
+						 offset + length - 1);
+	}
 
 	fuse_invalidate_attr_mask(inode, FUSE_STATX_MODSIZE);
 
@@ -3010,6 +3064,7 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	ssize_t err;
 	/* mark unstable when write-back is not used, and file_out gets
 	 * extended */
+	const bool is_iomap = fuse_inode_has_iomap(inode_out);
 	bool is_unstable = (!fc->writeback_cache) &&
 			   ((pos_out + len) > inode_out->i_size);
 
@@ -3053,6 +3108,10 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (err)
 		goto out;
 
+	/* See inode_dio_wait comment in fuse_file_fallocate */
+	if (is_iomap)
+		inode_dio_wait(inode_out);
+
 	if (is_unstable)
 		set_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state);
 
@@ -3075,7 +3134,8 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (err)
 		goto out;
 
-	truncate_inode_pages_range(inode_out->i_mapping,
+	if (!is_iomap)
+		truncate_inode_pages_range(inode_out->i_mapping,
 				   ALIGN_DOWN(pos_out, PAGE_SIZE),
 				   ALIGN(pos_out + outarg.size, PAGE_SIZE) - 1);
 
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 54e09f60980ef1..64f851d04a009b 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -5,6 +5,8 @@
  */
 #include <linux/iomap.h>
 #include <linux/fiemap.h>
+#include <linux/pagemap.h>
+#include <linux/falloc.h>
 #include "fuse_i.h"
 #include "fuse_trace.h"
 #include "iomap_priv.h"
@@ -241,7 +243,7 @@ static inline uint16_t fuse_iomap_flags_from_server(uint16_t fuse_f_flags)
 		ret |= FUSE_IOMAP_OP_##word
 static inline uint32_t fuse_iomap_op_to_server(unsigned iomap_op_flags)
 {
-	uint32_t ret = 0;
+	uint32_t ret = iomap_op_flags & FUSE_IOMAP_OP_WRITEBACK;
 
 	XMAP(WRITE);
 	XMAP(ZERO);
@@ -389,7 +391,8 @@ fuse_iomap_begin_validate(const struct inode *inode,
 
 static inline bool fuse_is_iomap_file_write(unsigned int opflags)
 {
-	return opflags & (IOMAP_WRITE | IOMAP_ZERO | IOMAP_UNSHARE);
+	return opflags & (IOMAP_WRITE | IOMAP_ZERO | IOMAP_UNSHARE |
+			  FUSE_IOMAP_OP_WRITEBACK);
 }
 
 static inline struct fuse_backing *
@@ -736,14 +739,7 @@ void fuse_iomap_unmount(struct fuse_mount *fm)
 	fuse_send_destroy(fm);
 }
 
-static inline void fuse_inode_set_iomap(struct inode *inode)
-{
-	struct fuse_inode *fi = get_fuse_inode(inode);
-
-	ASSERT(fuse_has_iomap(inode));
-
-	set_bit(FUSE_I_IOMAP, &fi->state);
-}
+static inline void fuse_inode_set_iomap(struct inode *inode);
 
 static inline void fuse_inode_clear_iomap(struct inode *inode)
 {
@@ -946,6 +942,110 @@ static const struct iomap_dio_ops fuse_iomap_dio_write_ops = {
 	.end_io		= fuse_iomap_dio_write_end_io,
 };
 
+static const struct iomap_write_ops fuse_iomap_write_ops = {
+};
+
+static int
+fuse_iomap_zero_range(
+	struct inode		*inode,
+	loff_t			pos,
+	loff_t			len,
+	bool			*did_zero)
+{
+	return iomap_zero_range(inode, pos, len, did_zero, &fuse_iomap_ops,
+				&fuse_iomap_write_ops, NULL);
+}
+
+/* Take care of zeroing post-EOF blocks when they might exist. */
+static ssize_t
+fuse_iomap_write_zero_eof(
+	struct kiocb		*iocb,
+	struct iov_iter		*from,
+	bool			*drained_dio)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct address_space *mapping = iocb->ki_filp->f_mapping;
+	loff_t			isize;
+	int			error;
+
+	/*
+	 * We need to serialise against EOF updates that occur in IO
+	 * completions here. We want to make sure that nobody is changing the
+	 * size while we do this check until we have placed an IO barrier (i.e.
+	 * hold i_rwsem exclusively) that prevents new IO from being
+	 * dispatched.  The spinlock effectively forms a memory barrier once we
+	 * have i_rwsem exclusively so we are guaranteed to see the latest EOF
+	 * value and hence be able to correctly determine if we need to run
+	 * zeroing.
+	 */
+	spin_lock(&fi->lock);
+	isize = i_size_read(inode);
+	if (iocb->ki_pos <= isize) {
+		spin_unlock(&fi->lock);
+		return 0;
+	}
+	spin_unlock(&fi->lock);
+
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		return -EAGAIN;
+
+	if (!(*drained_dio)) {
+		/*
+		 * We now have an IO submission barrier in place, but AIO can
+		 * do EOF updates during IO completion and hence we now need to
+		 * wait for all of them to drain.  Non-AIO DIO will have
+		 * drained before we are given the exclusive i_rwsem, and so
+		 * for most cases this wait is a no-op.
+		 */
+		inode_dio_wait(inode);
+		*drained_dio = true;
+		return 1;
+	}
+
+	filemap_invalidate_lock(mapping);
+	error = fuse_iomap_zero_range(inode, isize, iocb->ki_pos - isize, NULL);
+	filemap_invalidate_unlock(mapping);
+
+	return error;
+}
+
+static ssize_t
+fuse_iomap_write_checks(
+	struct kiocb		*iocb,
+	struct iov_iter		*from)
+{
+	struct inode		*inode = iocb->ki_filp->f_mapping->host;
+	ssize_t			error;
+	bool			drained_dio = false;
+
+restart:
+	error = generic_write_checks(iocb, from);
+	if (error <= 0)
+		return error;
+
+	/*
+	 * If the offset is beyond the size of the file, we need to zero all
+	 * blocks that fall between the existing EOF and the start of this
+	 * write.
+	 *
+	 * We can do an unlocked check for i_size here safely as I/O completion
+	 * can only extend EOF.  Truncate is locked out at this point, so the
+	 * EOF cannot move backwards, only forwards. Hence we only need to take
+	 * the slow path when we are at or beyond the current EOF.
+	 */
+	if (fuse_inode_has_iomap(inode) &&
+	    iocb->ki_pos > i_size_read(inode)) {
+		error = fuse_iomap_write_zero_eof(iocb, from, &drained_dio);
+		if (error == 1)
+			goto restart;
+		if (error)
+			return error;
+	}
+
+	return kiocb_modified(iocb);
+}
+
 ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from)
 {
 	struct inode *inode = file_inode(iocb->ki_filp);
@@ -973,8 +1073,9 @@ ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from)
 	ret = fuse_iomap_ilock_iocb(iocb, EXCL);
 	if (ret)
 		goto out_dsync;
-	ret = generic_write_checks(iocb, from);
-	if (ret <= 0)
+
+	ret = fuse_iomap_write_checks(iocb, from);
+	if (ret)
 		goto out_unlock;
 
 	/*
@@ -997,3 +1098,537 @@ ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from)
 	trace_fuse_iomap_direct_write_end(iocb, from, ret);
 	return ret;
 }
+
+struct fuse_writepage_ctx {
+	struct iomap_writepage_ctx ctx;
+};
+
+static void fuse_iomap_end_ioend(struct iomap_ioend *ioend)
+{
+	struct inode *inode = ioend->io_inode;
+	unsigned int ioendflags = FUSE_IOMAP_IOEND_WRITEBACK;
+	unsigned int nofs_flag;
+	int error = blk_status_to_errno(ioend->io_bio.bi_status);
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	if (fuse_is_bad(inode))
+		return;
+
+	if (ioend->io_flags & IOMAP_IOEND_SHARED)
+		ioendflags |= FUSE_IOMAP_IOEND_SHARED;
+	if (ioend->io_flags & IOMAP_IOEND_UNWRITTEN)
+		ioendflags |= FUSE_IOMAP_IOEND_UNWRITTEN;
+
+	/*
+	 * We can allocate memory here while doing writeback on behalf of
+	 * memory reclaim.  To avoid memory allocation deadlocks set the
+	 * task-wide nofs context for the following operations.
+	 */
+	nofs_flag = memalloc_nofs_save();
+	fuse_iomap_ioend(inode, ioend->io_offset, ioend->io_size, error,
+			 ioendflags, ioend->io_sector);
+	iomap_finish_ioends(ioend, error);
+	memalloc_nofs_restore(nofs_flag);
+}
+
+/*
+ * Finish all pending IO completions that require transactional modifications.
+ *
+ * We try to merge physical and logically contiguous ioends before completion to
+ * minimise the number of transactions we need to perform during IO completion.
+ * Both unwritten extent conversion and COW remapping need to iterate and modify
+ * one physical extent at a time, so we gain nothing by merging physically
+ * discontiguous extents here.
+ *
+ * The ioend chain length that we can be processing here is largely unbound in
+ * length and we may have to perform significant amounts of work on each ioend
+ * to complete it. Hence we have to be careful about holding the CPU for too
+ * long in this loop.
+ */
+static void fuse_iomap_end_io(struct work_struct *work)
+{
+	struct fuse_inode *fi =
+		container_of(work, struct fuse_inode, ioend_work);
+	struct iomap_ioend *ioend;
+	struct list_head tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&fi->ioend_lock, flags);
+	list_replace_init(&fi->ioend_list, &tmp);
+	spin_unlock_irqrestore(&fi->ioend_lock, flags);
+
+	iomap_sort_ioends(&tmp);
+	while ((ioend = list_first_entry_or_null(&tmp, struct iomap_ioend,
+			io_list))) {
+		list_del_init(&ioend->io_list);
+		iomap_ioend_try_merge(ioend, &tmp);
+		fuse_iomap_end_ioend(ioend);
+		cond_resched();
+	}
+}
+
+static void fuse_iomap_end_bio(struct bio *bio)
+{
+	struct iomap_ioend *ioend = iomap_ioend_from_bio(bio);
+	struct inode *inode = ioend->io_inode;
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	unsigned long flags;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	spin_lock_irqsave(&fi->ioend_lock, flags);
+	if (list_empty(&fi->ioend_list))
+		WARN_ON_ONCE(!queue_work(system_unbound_wq, &fi->ioend_work));
+	list_add_tail(&ioend->io_list, &fi->ioend_list);
+	spin_unlock_irqrestore(&fi->ioend_lock, flags);
+}
+
+/*
+ * Fast revalidation of the cached writeback mapping. Return true if the current
+ * mapping is valid, false otherwise.
+ */
+static bool fuse_iomap_revalidate_writeback(struct iomap_writepage_ctx *wpc,
+					    loff_t offset)
+{
+	if (offset < wpc->iomap.offset ||
+	    offset >= wpc->iomap.offset + wpc->iomap.length)
+		return false;
+
+	/* XXX actually use revalidation cookie */
+	return true;
+}
+
+/*
+ * If the folio has delalloc blocks on it, the caller is asking us to punch them
+ * out. If we don't, we can leave a stale delalloc mapping covered by a clean
+ * page that needs to be dirtied again before the delalloc mapping can be
+ * converted. This stale delalloc mapping can trip up a later direct I/O read
+ * operation on the same region.
+ *
+ * We prevent this by truncating away the delalloc regions on the folio. Because
+ * they are delalloc, we can do this without needing a transaction. Indeed - if
+ * we get ENOSPC errors, we have to be able to do this truncation without a
+ * transaction as there is no space left for block reservation (typically why
+ * we see a ENOSPC in writeback).
+ */
+static void fuse_iomap_discard_folio(struct folio *folio, loff_t pos, int error)
+{
+	struct inode *inode = folio->mapping->host;
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	loff_t end = folio_pos(folio) + folio_size(folio);
+
+	if (fuse_is_bad(inode))
+		return;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	printk_ratelimited(KERN_ERR
+		"page discard on page %px, inode 0x%llx, pos %llu.",
+			folio, fi->orig_ino, pos);
+
+	/* Userspace may need to remove delayed allocations */
+	fuse_iomap_ioend(inode, pos, end - pos, error, 0, FUSE_IOMAP_NULL_ADDR);
+}
+
+static ssize_t fuse_iomap_writeback_range(struct iomap_writepage_ctx *wpc,
+					  struct folio *folio, u64 offset,
+					  unsigned int len, u64 end_pos)
+{
+	struct inode *inode = wpc->inode;
+	struct iomap write_iomap, dontcare;
+	ssize_t ret;
+
+	if (fuse_is_bad(inode)) {
+		ret = -EIO;
+		goto discard_folio;
+	}
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	if (!fuse_iomap_revalidate_writeback(wpc, offset)) {
+		ret = fuse_iomap_begin(inode, offset, len,
+				       FUSE_IOMAP_OP_WRITEBACK,
+				       &write_iomap, &dontcare);
+		if (ret)
+			goto discard_folio;
+
+		/*
+		 * Landed in a hole or beyond EOF?  Send that to iomap, it'll
+		 * skip writing back the file range.
+		 */
+		if (write_iomap.offset > offset) {
+			write_iomap.length = write_iomap.offset - offset;
+			write_iomap.offset = offset;
+			write_iomap.type = IOMAP_HOLE;
+		}
+
+		memcpy(&wpc->iomap, &write_iomap, sizeof(struct iomap));
+	}
+
+	ret = iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
+	if (ret < 0)
+		goto discard_folio;
+
+	return ret;
+discard_folio:
+	fuse_iomap_discard_folio(folio, offset, ret);
+	return ret;
+}
+
+static int fuse_iomap_writeback_submit(struct iomap_writepage_ctx *wpc,
+				       int error)
+{
+	struct iomap_ioend *ioend = wpc->wb_ctx;
+
+	ASSERT(fuse_inode_has_iomap(ioend->io_inode));
+
+	/* always call our ioend function, even if we cancel the bio */
+	ioend->io_bio.bi_end_io = fuse_iomap_end_bio;
+	return iomap_ioend_writeback_submit(wpc, error);
+}
+
+static const struct iomap_writeback_ops fuse_iomap_writeback_ops = {
+	.writeback_range	= fuse_iomap_writeback_range,
+	.writeback_submit	= fuse_iomap_writeback_submit,
+};
+
+static int fuse_iomap_writepages(struct address_space *mapping,
+				 struct writeback_control *wbc)
+{
+	struct fuse_writepage_ctx wpc = {
+		.ctx = {
+			.inode = mapping->host,
+			.wbc = wbc,
+			.ops = &fuse_iomap_writeback_ops,
+		},
+	};
+
+	ASSERT(fuse_inode_has_iomap(mapping->host));
+
+	return iomap_writepages(&wpc.ctx);
+}
+
+static int fuse_iomap_read_folio(struct file *file, struct folio *folio)
+{
+	ASSERT(fuse_inode_has_iomap(file_inode(file)));
+
+	return iomap_read_folio(folio, &fuse_iomap_ops);
+}
+
+static void fuse_iomap_readahead(struct readahead_control *rac)
+{
+	ASSERT(fuse_inode_has_iomap(file_inode(rac->file)));
+
+	iomap_readahead(rac, &fuse_iomap_ops);
+}
+
+static const struct address_space_operations fuse_iomap_aops = {
+	.read_folio		= fuse_iomap_read_folio,
+	.readahead		= fuse_iomap_readahead,
+	.writepages		= fuse_iomap_writepages,
+	.dirty_folio		= iomap_dirty_folio,
+	.release_folio		= iomap_release_folio,
+	.invalidate_folio	= iomap_invalidate_folio,
+	.migrate_folio		= filemap_migrate_folio,
+	.is_partially_uptodate  = iomap_is_partially_uptodate,
+	.error_remove_folio	= generic_error_remove_folio,
+
+	/* These aren't pagecache operations per se */
+	.bmap			= fuse_bmap,
+};
+
+static inline void fuse_inode_set_iomap(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	ASSERT(fuse_has_iomap(inode));
+
+	inode->i_data.a_ops = &fuse_iomap_aops;
+
+	INIT_WORK(&fi->ioend_work, fuse_iomap_end_io);
+	INIT_LIST_HEAD(&fi->ioend_list);
+	spin_lock_init(&fi->ioend_lock);
+	set_bit(FUSE_I_IOMAP, &fi->state);
+}
+
+/*
+ * Locking for serialisation of IO during page faults. This results in a lock
+ * ordering of:
+ *
+ * mmap_lock (MM)
+ *   sb_start_pagefault(vfs, freeze)
+ *     invalidate_lock (vfs - truncate serialisation)
+ *       page_lock (MM)
+ *         i_lock (FUSE - extent map serialisation)
+ */
+static vm_fault_t fuse_iomap_page_mkwrite(struct vm_fault *vmf)
+{
+	struct inode *inode = file_inode(vmf->vma->vm_file);
+	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
+	vm_fault_t ret;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	sb_start_pagefault(inode->i_sb);
+	file_update_time(vmf->vma->vm_file);
+
+	filemap_invalidate_lock_shared(mapping);
+	ret = iomap_page_mkwrite(vmf, &fuse_iomap_ops, NULL);
+	filemap_invalidate_unlock_shared(mapping);
+
+	sb_end_pagefault(inode->i_sb);
+	return ret;
+}
+
+static const struct vm_operations_struct fuse_iomap_vm_ops = {
+	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
+	.page_mkwrite	= fuse_iomap_page_mkwrite,
+};
+
+int fuse_iomap_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	ASSERT(fuse_inode_has_iomap(file_inode(file)));
+
+	file_accessed(file);
+	vma->vm_ops = &fuse_iomap_vm_ops;
+	return 0;
+}
+
+ssize_t fuse_iomap_buffered_read(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t ret;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	if (!iov_iter_count(to))
+		return 0; /* skip atime */
+
+	file_accessed(iocb->ki_filp);
+
+	ret = fuse_iomap_ilock_iocb(iocb, SHARED);
+	if (ret)
+		return ret;
+	ret = generic_file_read_iter(iocb, to);
+	inode_unlock_shared(inode);
+
+	return ret;
+}
+
+ssize_t fuse_iomap_buffered_write(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	loff_t pos = iocb->ki_pos;
+	ssize_t ret;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	if (!iov_iter_count(from))
+		return 0;
+
+	ret = fuse_iomap_ilock_iocb(iocb, EXCL);
+	if (ret)
+		return ret;
+
+	ret = fuse_iomap_write_checks(iocb, from);
+	if (ret)
+		goto out_unlock;
+
+	if (inode->i_size < pos + iov_iter_count(from))
+		set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
+
+	ret = iomap_file_buffered_write(iocb, from, &fuse_iomap_ops,
+					&fuse_iomap_write_ops, NULL);
+
+	if (ret > 0)
+		fuse_write_update_attr(inode, pos + ret, ret);
+	clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
+
+out_unlock:
+	inode_unlock(inode);
+
+	if (ret > 0) {
+		/* Handle various SYNC-type writes */
+		ret = generic_write_sync(iocb, ret);
+	}
+	return ret;
+}
+
+static int
+fuse_iomap_truncate_page(
+	struct inode *inode,
+	loff_t			pos,
+	bool			*did_zero)
+{
+	return iomap_truncate_page(inode, pos, did_zero, &fuse_iomap_ops,
+				   &fuse_iomap_write_ops, NULL);
+}
+/*
+ * Truncate pagecache for a file before sending the truncate request to
+ * userspace.  Must have write permission and not be a directory.
+ *
+ * Caution: The caller of this function is responsible for calling
+ * setattr_prepare() or otherwise verifying the change is fine.
+ */
+int
+fuse_iomap_setsize_start(
+	struct inode		*inode,
+	loff_t			newsize)
+{
+	loff_t			oldsize = i_size_read(inode);
+	int			error;
+	bool			did_zeroing = false;
+
+	rwsem_assert_held_write(&inode->i_rwsem);
+	rwsem_assert_held_write(&inode->i_mapping->invalidate_lock);
+	ASSERT(S_ISREG(inode->i_mode));
+
+	/*
+	 * Wait for all direct I/O to complete.
+	 */
+	inode_dio_wait(inode);
+
+	/*
+	 * File data changes must be complete and flushed to disk before we
+	 * call userspace to modify the inode.
+	 *
+	 * Start with zeroing any data beyond EOF that we may expose on file
+	 * extension, or zeroing out the rest of the block on a downward
+	 * truncate.
+	 */
+	if (newsize > oldsize)
+		error = fuse_iomap_zero_range(inode, oldsize, newsize - oldsize,
+					      &did_zeroing);
+	else
+		error = fuse_iomap_truncate_page(inode, newsize, &did_zeroing);
+	if (error)
+		return error;
+
+	/*
+	 * We've already locked out new page faults, so now we can safely
+	 * remove pages from the page cache knowing they won't get refaulted
+	 * until we drop the mapping invalidation lock after the extent
+	 * manipulations are complete. The truncate_setsize() call also cleans
+	 * folios spanning EOF on extending truncates and hence ensures
+	 * sub-page block size filesystems are correctly handled, too.
+	 *
+	 * And we update in-core i_size and truncate page cache beyond newsize
+	 * before writing back the whole file, so we're guaranteed not to write
+	 * stale data past the new EOF on truncate down.
+	 */
+	truncate_setsize(inode, newsize);
+
+	/*
+	 * Flush the entire pagecache to ensure the fuse server logs the inode
+	 * size change and all dirty data that might be associated with it.
+	 * We don't know the ondisk inode size, so we only have this clumsy
+	 * hammer.
+	 */
+	return filemap_write_and_wait(inode->i_mapping);
+}
+
+/*
+ * Prepare for a file data block remapping operation by flushing and unmapping
+ * all pagecache for the entire range.
+ */
+int fuse_iomap_flush_unmap_range(struct inode *inode, loff_t pos,
+				 loff_t endpos)
+{
+	loff_t			start, end;
+	unsigned int		rounding;
+	int			error;
+
+	/*
+	 * Make sure we extend the flush out to extent alignment boundaries so
+	 * any extent range overlapping the start/end of the modification we
+	 * are about to do is clean and idle.
+	 */
+	rounding = max_t(unsigned int, i_blocksize(inode), PAGE_SIZE);
+	start = round_down(pos, rounding);
+	end = round_up(endpos + 1, rounding) - 1;
+
+	error = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (error)
+		return error;
+	truncate_pagecache_range(inode, start, end);
+	return 0;
+}
+
+static int fuse_iomap_punch_range(struct inode *inode, loff_t offset,
+				  loff_t length)
+{
+	loff_t isize = i_size_read(inode);
+	int error;
+
+	/*
+	 * Now that we've unmap all full blocks we'll have to zero out any
+	 * partial block at the beginning and/or end.  iomap_zero_range is
+	 * smart enough to skip holes and unwritten extents, including those we
+	 * just created, but we must take care not to zero beyond EOF, which
+	 * would enlarge i_size.
+	 */
+	if (offset >= isize)
+		return 0;
+	if (offset + length > isize)
+		length = isize - offset;
+	error = fuse_iomap_zero_range(inode, offset, length, NULL);
+	if (error)
+		return error;
+
+	/*
+	 * If we zeroed right up to EOF and EOF straddles a page boundary we
+	 * must make sure that the post-EOF area is also zeroed because the
+	 * page could be mmap'd and iomap_zero_range doesn't do that for us.
+	 * Writeback of the eof page will do this, albeit clumsily.
+	 */
+	if (offset + length >= isize && offset_in_page(offset + length) > 0) {
+		error = filemap_write_and_wait_range(inode->i_mapping,
+					round_down(offset + length, PAGE_SIZE),
+					LLONG_MAX);
+	}
+
+	return error;
+}
+
+int
+fuse_iomap_fallocate(
+	struct file		*file,
+	int			mode,
+	loff_t			offset,
+	loff_t			length,
+	loff_t			new_size)
+{
+	struct inode *inode = file_inode(file);
+	int error;
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	/*
+	 * If we unmapped blocks from the file range, then we zero the
+	 * pagecache for those regions and push them to disk rather than make
+	 * the fuse server manually zero the disk blocks.
+	 */
+	if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) {
+		error = fuse_iomap_punch_range(inode, offset, length);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * If this is an extending write, we need to zero the bytes beyond the
+	 * new EOF and bounce the new size out to userspace.
+	 */
+	if (new_size) {
+		error = fuse_iomap_setsize_start(inode, new_size);
+		if (error)
+			return error;
+
+		fuse_write_update_attr(inode, new_size, length);
+	}
+
+	file_update_time(file);
+	return 0;
+}

[PATCH 15/28] fuse_trace: implement buffered IO with iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |  252 ++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |   40 ++++++++
 2 files changed, 288 insertions(+), 4 deletions(-)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 434d38ce89c428..e69ad48b14066b 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -224,6 +224,9 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 #endif /* CONFIG_FUSE_BACKING */
 
 #if IS_ENABLED(CONFIG_FUSE_IOMAP)
+struct iomap_writepage_ctx;
+struct iomap_ioend;
+
 /* tracepoint boilerplate so we don't have to keep doing this */
 #define FUSE_IOMAP_OPFLAGS_FIELD \
 		__field(unsigned,		opflags)
@@ -291,7 +294,8 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 	{ FUSE_IOMAP_OP_UNSHARE,		"unshare" }, \
 	{ FUSE_IOMAP_OP_DAX,			"fsdax" }, \
 	{ FUSE_IOMAP_OP_ATOMIC,			"atomic" }, \
-	{ FUSE_IOMAP_OP_DONTCACHE,		"dontcache" }
+	{ FUSE_IOMAP_OP_DONTCACHE,		"dontcache" }, \
+	{ FUSE_IOMAP_OP_WRITEBACK,		"writeback" }
 
 #define FUSE_IOMAP_TYPE_STRINGS \
 	{ FUSE_IOMAP_TYPE_PURE_OVERWRITE,	"overwrite" }, \
@@ -306,7 +310,8 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 	{ FUSE_IOMAP_IOEND_UNWRITTEN,		"unwritten" }, \
 	{ FUSE_IOMAP_IOEND_BOUNDARY,		"boundary" }, \
 	{ FUSE_IOMAP_IOEND_DIRECT,		"direct" }, \
-	{ FUSE_IOMAP_IOEND_APPEND,		"append" }
+	{ FUSE_IOMAP_IOEND_APPEND,		"append" }, \
+	{ FUSE_IOMAP_IOEND_WRITEBACK,		"writeback" }
 
 #define IOMAP_DIOEND_STRINGS \
 	{ IOMAP_DIO_UNWRITTEN,			"unwritten" }, \
@@ -329,6 +334,12 @@ TRACE_DEFINE_ENUM(FUSE_I_IOMAP);
 	{ 1 << FUSE_I_CACHE_IO_MODE,		"cacheio" }, \
 	{ 1 << FUSE_I_IOMAP,			"iomap" }
 
+#define IOMAP_IOEND_STRINGS \
+	{ IOMAP_IOEND_SHARED,			"shared" }, \
+	{ IOMAP_IOEND_UNWRITTEN,		"unwritten" }, \
+	{ IOMAP_IOEND_BOUNDARY,			"boundary" }, \
+	{ IOMAP_IOEND_DIRECT,			"direct" }
+
 DECLARE_EVENT_CLASS(fuse_iomap_check_class,
 	TP_PROTO(const char *func, int line, const char *condition),
 
@@ -668,6 +679,9 @@ DEFINE_EVENT(fuse_iomap_file_io_class, name,		\
 	TP_ARGS(iocb, iter))
 DEFINE_FUSE_IOMAP_FILE_IO_EVENT(fuse_iomap_direct_read);
 DEFINE_FUSE_IOMAP_FILE_IO_EVENT(fuse_iomap_direct_write);
+DEFINE_FUSE_IOMAP_FILE_IO_EVENT(fuse_iomap_buffered_read);
+DEFINE_FUSE_IOMAP_FILE_IO_EVENT(fuse_iomap_buffered_write);
+DEFINE_FUSE_IOMAP_FILE_IO_EVENT(fuse_iomap_write_zero_eof);
 
 DECLARE_EVENT_CLASS(fuse_iomap_file_ioend_class,
 	TP_PROTO(const struct kiocb *iocb, const struct iov_iter *iter,
@@ -694,6 +708,8 @@ DEFINE_EVENT(fuse_iomap_file_ioend_class, name,		\
 	TP_ARGS(iocb, iter, ret))
 DEFINE_FUSE_IOMAP_FILE_IOEND_EVENT(fuse_iomap_direct_read_end);
 DEFINE_FUSE_IOMAP_FILE_IOEND_EVENT(fuse_iomap_direct_write_end);
+DEFINE_FUSE_IOMAP_FILE_IOEND_EVENT(fuse_iomap_buffered_read_end);
+DEFINE_FUSE_IOMAP_FILE_IOEND_EVENT(fuse_iomap_buffered_write_end);
 
 TRACE_EVENT(fuse_iomap_dio_write_end_io,
 	TP_PROTO(const struct inode *inode, loff_t pos, ssize_t written,
@@ -720,6 +736,238 @@ TRACE_EVENT(fuse_iomap_dio_write_end_io,
 		  __print_flags(__entry->dioendflags, "|", IOMAP_DIOEND_STRINGS),
 		  __entry->error)
 );
+
+TRACE_EVENT(fuse_iomap_end_ioend,
+	TP_PROTO(const struct iomap_ioend *ioend),
+
+	TP_ARGS(ioend),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(unsigned int,		ioendflags)
+		__field(int,			error)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(ioend->io_inode, fi, fm);
+		__entry->offset		=	ioend->io_offset;
+		__entry->length		=	ioend->io_size;
+		__entry->ioendflags	=	ioend->io_flags;
+		__entry->error		=	blk_status_to_errno(ioend->io_bio.bi_status);
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() " ioendflags (%s) error %d",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __print_flags(__entry->ioendflags, "|", IOMAP_IOEND_STRINGS),
+		  __entry->error)
+);
+
+TRACE_EVENT(fuse_iomap_writeback_range,
+	TP_PROTO(const struct inode *inode, u64 offset, unsigned int count,
+		 u64 end_pos),
+
+	TP_ARGS(inode, offset, count, end_pos),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(uint64_t,		end_pos)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	offset;
+		__entry->length		=	count;
+		__entry->end_pos	=	end_pos;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() " end_pos 0x%llx",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __entry->end_pos)
+);
+
+TRACE_EVENT(fuse_iomap_writeback_submit,
+	TP_PROTO(const struct iomap_writepage_ctx *wpc, int error),
+
+	TP_ARGS(wpc, error),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(unsigned int,		nr_folios)
+		__field(uint64_t,		addr)
+		__field(int,			error)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(wpc->inode, fi, fm);
+		__entry->nr_folios	=	wpc->nr_folios;
+		__entry->offset		=	wpc->iomap.offset;
+		__entry->length		=	wpc->iomap.length;
+		__entry->addr		=	wpc->iomap.addr << 9;
+		__entry->error		=	error;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() " addr 0x%llx nr_folios %u error %d",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __entry->addr,
+		  __entry->nr_folios,
+		  __entry->error)
+);
+
+TRACE_EVENT(fuse_iomap_discard_folio,
+	TP_PROTO(const struct inode *inode, loff_t offset, size_t count),
+
+	TP_ARGS(inode, offset, count),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	offset;
+		__entry->length		=	count;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT(),
+		  FUSE_IO_RANGE_PRINTK_ARGS())
+);
+
+TRACE_EVENT(fuse_iomap_writepages,
+	TP_PROTO(const struct inode *inode, const struct writeback_control *wbc),
+
+	TP_ARGS(inode, wbc),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(long,			nr_to_write)
+		__field(bool,			sync_all)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	wbc->range_start;
+		__entry->length		=	wbc->range_end - wbc->range_start + 1;
+		__entry->nr_to_write	=	wbc->nr_to_write;
+		__entry->sync_all	=	wbc->sync_mode == WB_SYNC_ALL;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() " nr_folios %ld sync_all? %d",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __entry->nr_to_write,
+		  __entry->sync_all)
+);
+
+TRACE_EVENT(fuse_iomap_read_folio,
+	TP_PROTO(const struct folio *folio),
+
+	TP_ARGS(folio),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(folio->mapping->host, fi, fm);
+		__entry->offset		=	folio_pos(folio);
+		__entry->length		=	folio_size(folio);
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT(),
+		  FUSE_IO_RANGE_PRINTK_ARGS())
+);
+
+TRACE_EVENT(fuse_iomap_readahead,
+	TP_PROTO(const struct readahead_control *rac),
+
+	TP_ARGS(rac),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+	),
+
+	TP_fast_assign(
+		struct readahead_control *mutrac = (struct readahead_control *)rac;
+		FUSE_INODE_ASSIGN(file_inode(rac->file), fi, fm);
+		__entry->offset		=	readahead_pos(mutrac);
+		__entry->length		=	readahead_length(mutrac);
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT(),
+		  FUSE_IO_RANGE_PRINTK_ARGS())
+);
+
+TRACE_EVENT(fuse_iomap_page_mkwrite,
+	TP_PROTO(const struct vm_fault *vmf),
+
+	TP_ARGS(vmf),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+	),
+
+	TP_fast_assign(
+		struct folio *folio = page_folio(vmf->page);
+		FUSE_INODE_ASSIGN(file_inode(vmf->vma->vm_file), fi, fm);
+		__entry->offset		=	folio_pos(folio);
+		__entry->length		=	folio_size(folio);
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT(),
+		  FUSE_IO_RANGE_PRINTK_ARGS())
+);
+
+DECLARE_EVENT_CLASS(fuse_iomap_file_range_class,
+	TP_PROTO(const struct inode *inode, loff_t offset, loff_t length),
+
+	TP_ARGS(inode, offset, length),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	offset;
+		__entry->length		=	length;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT(),
+		  FUSE_IO_RANGE_PRINTK_ARGS())
+)
+#define DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(name)		\
+DEFINE_EVENT(fuse_iomap_file_range_class, name,		\
+	TP_PROTO(const struct inode *inode, loff_t offset, loff_t length), \
+	TP_ARGS(inode, offset, length))
+DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_truncate_up);
+DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_truncate_down);
+DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_punch_range);
+DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_setsize);
+DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_flush_unmap_range);
+
+TRACE_EVENT(fuse_iomap_fallocate,
+	TP_PROTO(const struct inode *inode, int mode, loff_t offset,
+		 loff_t length, loff_t newsize),
+	TP_ARGS(inode, mode, offset, length, newsize),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		__field(loff_t,			newsize)
+		__field(int,			mode)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	offset;
+		__entry->length		=	length;
+		__entry->mode		=	mode;
+		__entry->newsize	=	newsize;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() " mode 0x%x newsize 0x%llx",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  __entry->mode,
+		  __entry->newsize)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 64f851d04a009b..d771b1068fb912 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1003,6 +1003,8 @@ fuse_iomap_write_zero_eof(
 		return 1;
 	}
 
+	trace_fuse_iomap_write_zero_eof(iocb, from);
+
 	filemap_invalidate_lock(mapping);
 	error = fuse_iomap_zero_range(inode, isize, iocb->ki_pos - isize, NULL);
 	filemap_invalidate_unlock(mapping);
@@ -1115,6 +1117,8 @@ static void fuse_iomap_end_ioend(struct iomap_ioend *ioend)
 	if (fuse_is_bad(inode))
 		return;
 
+	trace_fuse_iomap_end_ioend(ioend);
+
 	if (ioend->io_flags & IOMAP_IOEND_SHARED)
 		ioendflags |= FUSE_IOMAP_IOEND_SHARED;
 	if (ioend->io_flags & IOMAP_IOEND_UNWRITTEN)
@@ -1223,6 +1227,8 @@ static void fuse_iomap_discard_folio(struct folio *folio, loff_t pos, int error)
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_discard_folio(inode, pos, folio_size(folio));
+
 	printk_ratelimited(KERN_ERR
 		"page discard on page %px, inode 0x%llx, pos %llu.",
 			folio, fi->orig_ino, pos);
@@ -1246,6 +1252,8 @@ static ssize_t fuse_iomap_writeback_range(struct iomap_writepage_ctx *wpc,
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_writeback_range(inode, offset, len, end_pos);
+
 	if (!fuse_iomap_revalidate_writeback(wpc, offset)) {
 		ret = fuse_iomap_begin(inode, offset, len,
 				       FUSE_IOMAP_OP_WRITEBACK,
@@ -1283,6 +1291,8 @@ static int fuse_iomap_writeback_submit(struct iomap_writepage_ctx *wpc,
 
 	ASSERT(fuse_inode_has_iomap(ioend->io_inode));
 
+	trace_fuse_iomap_writeback_submit(wpc, error);
+
 	/* always call our ioend function, even if we cancel the bio */
 	ioend->io_bio.bi_end_io = fuse_iomap_end_bio;
 	return iomap_ioend_writeback_submit(wpc, error);
@@ -1306,6 +1316,8 @@ static int fuse_iomap_writepages(struct address_space *mapping,
 
 	ASSERT(fuse_inode_has_iomap(mapping->host));
 
+	trace_fuse_iomap_writepages(mapping->host, wbc);
+
 	return iomap_writepages(&wpc.ctx);
 }
 
@@ -1313,6 +1325,8 @@ static int fuse_iomap_read_folio(struct file *file, struct folio *folio)
 {
 	ASSERT(fuse_inode_has_iomap(file_inode(file)));
 
+	trace_fuse_iomap_read_folio(folio);
+
 	return iomap_read_folio(folio, &fuse_iomap_ops);
 }
 
@@ -1320,6 +1334,8 @@ static void fuse_iomap_readahead(struct readahead_control *rac)
 {
 	ASSERT(fuse_inode_has_iomap(file_inode(rac->file)));
 
+	trace_fuse_iomap_readahead(rac);
+
 	iomap_readahead(rac, &fuse_iomap_ops);
 }
 
@@ -1370,6 +1386,8 @@ static vm_fault_t fuse_iomap_page_mkwrite(struct vm_fault *vmf)
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_page_mkwrite(vmf);
+
 	sb_start_pagefault(inode->i_sb);
 	file_update_time(vmf->vma->vm_file);
 
@@ -1403,6 +1421,8 @@ ssize_t fuse_iomap_buffered_read(struct kiocb *iocb, struct iov_iter *to)
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_buffered_read(iocb, to);
+
 	if (!iov_iter_count(to))
 		return 0; /* skip atime */
 
@@ -1414,6 +1434,7 @@ ssize_t fuse_iomap_buffered_read(struct kiocb *iocb, struct iov_iter *to)
 	ret = generic_file_read_iter(iocb, to);
 	inode_unlock_shared(inode);
 
+	trace_fuse_iomap_buffered_read_end(iocb, to, ret);
 	return ret;
 }
 
@@ -1426,6 +1447,8 @@ ssize_t fuse_iomap_buffered_write(struct kiocb *iocb, struct iov_iter *from)
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_buffered_write(iocb, from);
+
 	if (!iov_iter_count(from))
 		return 0;
 
@@ -1454,6 +1477,7 @@ ssize_t fuse_iomap_buffered_write(struct kiocb *iocb, struct iov_iter *from)
 		/* Handle various SYNC-type writes */
 		ret = generic_write_sync(iocb, ret);
 	}
+	trace_fuse_iomap_buffered_write_end(iocb, from, ret);
 	return ret;
 }
 
@@ -1499,11 +1523,17 @@ fuse_iomap_setsize_start(
 	 * extension, or zeroing out the rest of the block on a downward
 	 * truncate.
 	 */
-	if (newsize > oldsize)
+	if (newsize > oldsize) {
+		trace_fuse_iomap_truncate_up(inode, oldsize, newsize - oldsize);
+
 		error = fuse_iomap_zero_range(inode, oldsize, newsize - oldsize,
 					      &did_zeroing);
-	else
+	} else {
+		trace_fuse_iomap_truncate_down(inode, newsize,
+					       oldsize - newsize);
+
 		error = fuse_iomap_truncate_page(inode, newsize, &did_zeroing);
+	}
 	if (error)
 		return error;
 
@@ -1550,6 +1580,8 @@ int fuse_iomap_flush_unmap_range(struct inode *inode, loff_t pos,
 	start = round_down(pos, rounding);
 	end = round_up(endpos + 1, rounding) - 1;
 
+	trace_fuse_iomap_flush_unmap_range(inode, start, end + 1 - start);
+
 	error = filemap_write_and_wait_range(inode->i_mapping, start, end);
 	if (error)
 		return error;
@@ -1563,6 +1595,8 @@ static int fuse_iomap_punch_range(struct inode *inode, loff_t offset,
 	loff_t isize = i_size_read(inode);
 	int error;
 
+	trace_fuse_iomap_punch_range(inode, offset, length);
+
 	/*
 	 * Now that we've unmap all full blocks we'll have to zero out any
 	 * partial block at the beginning and/or end.  iomap_zero_range is
@@ -1606,6 +1640,8 @@ fuse_iomap_fallocate(
 
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_fallocate(inode, mode, offset, length, new_size);
+
 	/*
 	 * If we unmapped blocks from the file range, then we zero the
 	 * pagecache for those regions and push them to disk rather than make

[PATCH 16/28] fuse: implement large folios for iomap pagecache files

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Use large folios when we're using iomap.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/file_iomap.c |    6 ++++++
 1 file changed, 6 insertions(+)


diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index d771b1068fb912..c09e00c7de2694 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1357,6 +1357,7 @@ static const struct address_space_operations fuse_iomap_aops = {
 static inline void fuse_inode_set_iomap(struct inode *inode)
 {
 	struct fuse_inode *fi = get_fuse_inode(inode);
+	unsigned int min_order = 0;
 
 	ASSERT(fuse_has_iomap(inode));
 
@@ -1365,6 +1366,11 @@ static inline void fuse_inode_set_iomap(struct inode *inode)
 	INIT_WORK(&fi->ioend_work, fuse_iomap_end_io);
 	INIT_LIST_HEAD(&fi->ioend_list);
 	spin_lock_init(&fi->ioend_lock);
+
+	if (inode->i_blkbits > PAGE_SHIFT)
+		min_order = inode->i_blkbits - PAGE_SHIFT;
+
+	mapping_set_folio_min_order(inode->i_mapping, min_order);
 	set_bit(FUSE_I_IOMAP, &fi->state);
 }
 

[PATCH 17/28] fuse: use an unrestricted backing device with iomap pagecache io

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

With iomap support turned on for the pagecache, the kernel issues
writeback to directly to block devices and we no longer have to push all
those pages through the fuse device to userspace.  Therefore, we don't
need the tight dirty limits (~1M) that are used for regular fuse.  This
dramatically increases the performance of fuse's pagecache IO.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/file_iomap.c |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)


diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index c09e00c7de2694..6cc1f91fe3d5a4 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -711,6 +711,27 @@ const struct fuse_backing_ops fuse_iomap_backing_ops = {
 void fuse_iomap_mount(struct fuse_mount *fm)
 {
 	struct fuse_conn *fc = fm->fc;
+	struct super_block *sb = fm->sb;
+	struct backing_dev_info *old_bdi = sb->s_bdi;
+	char *suffix = sb->s_bdev ? "-fuseblk" : "-fuse";
+	int res;
+
+	/*
+	 * sb->s_bdi points to the initial private bdi.  However, we want to
+	 * redirect it to a new private bdi with default dirty and readahead
+	 * settings because iomap writeback won't be pushing a ton of dirty
+	 * data through the fuse device.  If this fails we fall back to the
+	 * initial fuse bdi.
+	 */
+	sb->s_bdi = &noop_backing_dev_info;
+	res = super_setup_bdi_name(sb, "%u:%u%s.iomap", MAJOR(fc->dev),
+				   MINOR(fc->dev), suffix);
+	if (res) {
+		sb->s_bdi = old_bdi;
+	} else {
+		bdi_unregister(old_bdi);
+		bdi_put(old_bdi);
+	}
 
 	/*
 	 * Enable syncfs for iomap fuse servers so that we can send a final

[PATCH 18/28] fuse: advertise support for iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Advertise our new IO paths programmatically by creating an ioctl that
can return the capabilities of the kernel.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |    4 ++++
 include/uapi/linux/fuse.h |    9 +++++++++
 fs/fuse/dev.c             |    3 +++
 fs/fuse/file_iomap.c      |   13 +++++++++++++
 4 files changed, 29 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 7581d22de2340c..82191e92c21097 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1781,6 +1781,9 @@ int fuse_iomap_fallocate(struct file *file, int mode, loff_t offset,
 			 loff_t length, loff_t new_size);
 int fuse_iomap_flush_unmap_range(struct inode *inode, loff_t pos,
 				 loff_t endpos);
+
+int fuse_dev_ioctl_iomap_support(struct file *file,
+				 struct fuse_iomap_support __user *argp);
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
@@ -1803,6 +1806,7 @@ int fuse_iomap_flush_unmap_range(struct inode *inode, loff_t pos,
 # define fuse_iomap_setsize_start(...)		(-ENOSYS)
 # define fuse_iomap_fallocate(...)		(-ENOSYS)
 # define fuse_iomap_flush_unmap_range(...)	(-ENOSYS)
+# define fuse_dev_ioctl_iomap_support(...)	(-EOPNOTSUPP)
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index c0af8a4d3e30d8..675b1d4fdff8db 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1139,6 +1139,13 @@ struct fuse_backing_map {
 	uint64_t	padding;
 };
 
+/* basic file I/O functionality through iomap */
+#define FUSE_IOMAP_SUPPORT_FILEIO	(1ULL << 0)
+struct fuse_iomap_support {
+	uint64_t	flags;
+	uint64_t	padding;
+};
+
 /* Device ioctls: */
 #define FUSE_DEV_IOC_MAGIC		229
 #define FUSE_DEV_IOC_CLONE		_IOR(FUSE_DEV_IOC_MAGIC, 0, uint32_t)
@@ -1146,6 +1153,8 @@ struct fuse_backing_map {
 					     struct fuse_backing_map)
 #define FUSE_DEV_IOC_BACKING_CLOSE	_IOW(FUSE_DEV_IOC_MAGIC, 2, uint32_t)
 #define FUSE_DEV_IOC_SYNC_INIT		_IO(FUSE_DEV_IOC_MAGIC, 3)
+#define FUSE_DEV_IOC_IOMAP_SUPPORT	_IOR(FUSE_DEV_IOC_MAGIC, 99, \
+					     struct fuse_iomap_support)
 
 struct fuse_lseek_in {
 	uint64_t	fh;
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 871877cac2acf3..bb0ec19a368bea 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2710,6 +2710,9 @@ static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 	case FUSE_DEV_IOC_SYNC_INIT:
 		return fuse_dev_ioctl_sync_init(file);
 
+	case FUSE_DEV_IOC_IOMAP_SUPPORT:
+		return fuse_dev_ioctl_iomap_support(file, argp);
+
 	default:
 		return -ENOTTY;
 	}
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 6cc1f91fe3d5a4..5cefceb267f8f1 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1695,3 +1695,16 @@ fuse_iomap_fallocate(
 	file_update_time(file);
 	return 0;
 }
+
+int fuse_dev_ioctl_iomap_support(struct file *file,
+				 struct fuse_iomap_support __user *argp)
+{
+	struct fuse_iomap_support ios = { };
+
+	if (fuse_iomap_enabled())
+		ios.flags = FUSE_IOMAP_SUPPORT_FILEIO;
+
+	if (copy_to_user(argp, &ios, sizeof(ios)))
+		return -EFAULT;
+	return 0;
+}

[PATCH 19/28] fuse: query filesystem geometry when using iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add a new upcall to the fuse server so that the kernel can request
filesystem geometry bits when iomap mode is in use.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |   10 ++-
 include/uapi/linux/fuse.h |   39 ++++++++++++
 fs/fuse/file_iomap.c      |  147 +++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/inode.c           |   42 ++++++++++---
 4 files changed, 227 insertions(+), 11 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 82191e92c21097..e45780f6fe9e39 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1019,6 +1019,9 @@ struct fuse_conn {
 	struct fuse_ring *ring;
 #endif
 
+	/** How many subsystems still need initialization? */
+	atomic_t need_init;
+
 	/** Only used if the connection opts into request timeouts */
 	struct {
 		/* Worker for checking if any requests have timed out */
@@ -1431,6 +1434,7 @@ struct fuse_dev *fuse_dev_alloc(void);
 void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc);
 void fuse_dev_free(struct fuse_dev *fud);
 int fuse_send_init(struct fuse_mount *fm);
+void fuse_finish_init(struct fuse_conn *fc, bool ok);
 
 /**
  * Fill in superblock and initialize fuse connection
@@ -1739,7 +1743,8 @@ static inline bool fuse_has_iomap(const struct inode *inode)
 
 extern const struct fuse_backing_ops fuse_iomap_backing_ops;
 
-void fuse_iomap_mount(struct fuse_mount *fm);
+int fuse_iomap_mount(struct fuse_mount *fm);
+void fuse_iomap_mount_async(struct fuse_mount *fm);
 void fuse_iomap_unmount(struct fuse_mount *fm);
 
 void fuse_iomap_init_inode(struct inode *inode, unsigned attr_flags);
@@ -1787,7 +1792,8 @@ int fuse_dev_ioctl_iomap_support(struct file *file,
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
-# define fuse_iomap_mount(...)			((void)0)
+# define fuse_iomap_mount(...)			(0)
+# define fuse_iomap_mount_async(...)		((void)0)
 # define fuse_iomap_unmount(...)		((void)0)
 # define fuse_iomap_init_inode(...)		((void)0)
 # define fuse_iomap_evict_inode(...)		((void)0)
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 675b1d4fdff8db..19c1ac5006faa9 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -239,6 +239,7 @@
  *  7.99
  *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
  *  - add FUSE_ATTR_IOMAP to enable iomap for specific inodes
+ *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
  */
 
 #ifndef _LINUX_FUSE_H
@@ -666,6 +667,7 @@ enum fuse_opcode {
 	FUSE_TMPFILE		= 51,
 	FUSE_STATX		= 52,
 
+	FUSE_IOMAP_CONFIG	= 4092,
 	FUSE_IOMAP_IOEND	= 4093,
 	FUSE_IOMAP_BEGIN	= 4094,
 	FUSE_IOMAP_END		= 4095,
@@ -1425,4 +1427,41 @@ struct fuse_iomap_ioend_in {
 	uint32_t reserved1;	/* zero */
 };
 
+struct fuse_iomap_config_in {
+	uint64_t flags;		/* supported FUSE_IOMAP_CONFIG_* flags */
+	int64_t maxbytes;	/* maximum supported file size */
+	uint64_t padding[6];	/* zero */
+};
+
+/* Which fields are set in fuse_iomap_config_out? */
+#define FUSE_IOMAP_CONFIG_SID		(1 << 0ULL)
+#define FUSE_IOMAP_CONFIG_UUID		(1 << 1ULL)
+#define FUSE_IOMAP_CONFIG_BLOCKSIZE	(1 << 2ULL)
+#define FUSE_IOMAP_CONFIG_MAX_LINKS	(1 << 3ULL)
+#define FUSE_IOMAP_CONFIG_TIME		(1 << 4ULL)
+#define FUSE_IOMAP_CONFIG_MAXBYTES	(1 << 5ULL)
+
+struct fuse_iomap_config_out {
+	uint64_t flags;		/* FUSE_IOMAP_CONFIG_* */
+
+	char s_id[32];		/* Informational name */
+	char s_uuid[16];	/* UUID */
+
+	uint8_t s_uuid_len;	/* length of s_uuid */
+
+	uint8_t s_pad[3];	/* must be zeroes */
+
+	uint32_t s_blocksize;	/* fs block size */
+	uint32_t s_max_links;	/* max hard links */
+
+	/* Granularity of c/m/atime in ns (cannot be worse than a second) */
+	uint32_t s_time_gran;
+
+	/* Time limits for c/m/atime in seconds */
+	int64_t s_time_min;
+	int64_t s_time_max;
+
+	int64_t s_maxbytes;	/* max file size */
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 5cefceb267f8f1..abba22107718d9 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -708,14 +708,103 @@ const struct fuse_backing_ops fuse_iomap_backing_ops = {
 	.post_open = fuse_iomap_post_open,
 };
 
-void fuse_iomap_mount(struct fuse_mount *fm)
+struct fuse_iomap_config_args {
+	struct fuse_args args;
+	struct fuse_iomap_config_in inarg;
+	struct fuse_iomap_config_out outarg;
+};
+
+#define FUSE_IOMAP_CONFIG_ALL (FUSE_IOMAP_CONFIG_SID | \
+			       FUSE_IOMAP_CONFIG_UUID | \
+			       FUSE_IOMAP_CONFIG_BLOCKSIZE | \
+			       FUSE_IOMAP_CONFIG_MAX_LINKS | \
+			       FUSE_IOMAP_CONFIG_TIME | \
+			       FUSE_IOMAP_CONFIG_MAXBYTES)
+
+static int fuse_iomap_process_config(struct fuse_mount *fm, int error,
+				     const struct fuse_iomap_config_out *outarg)
 {
+	struct super_block *sb = fm->sb;
+
+	switch (error) {
+	case 0:
+		break;
+	case -ENOSYS:
+		return 0;
+	default:
+		return error;
+	}
+
+	if (outarg->flags & ~FUSE_IOMAP_CONFIG_ALL)
+		return -EINVAL;
+
+	if (outarg->s_uuid_len > sizeof(outarg->s_uuid))
+		return -EINVAL;
+
+	if (memchr_inv(outarg->s_pad, 0, sizeof(outarg->s_pad)))
+		return -EINVAL;
+
+	if (outarg->flags & FUSE_IOMAP_CONFIG_BLOCKSIZE) {
+		if (sb->s_bdev) {
+#ifdef CONFIG_BLOCK
+			if (!sb_set_blocksize(sb, outarg->s_blocksize))
+				return -EINVAL;
+#else
+			/*
+			 * XXX: how do we have a bdev filesystem without
+			 * CONFIG_BLOCK???
+			 */
+			return -EINVAL;
+#endif
+		} else {
+			sb->s_blocksize = outarg->s_blocksize;
+			sb->s_blocksize_bits = blksize_bits(outarg->s_blocksize);
+		}
+	}
+
+	if (outarg->flags & FUSE_IOMAP_CONFIG_SID)
+		memcpy(sb->s_id, outarg->s_id, sizeof(sb->s_id));
+
+	if (outarg->flags & FUSE_IOMAP_CONFIG_UUID) {
+		memcpy(&sb->s_uuid, outarg->s_uuid, outarg->s_uuid_len);
+		sb->s_uuid_len = outarg->s_uuid_len;
+	}
+
+	if (outarg->flags & FUSE_IOMAP_CONFIG_MAX_LINKS)
+		sb->s_max_links = outarg->s_max_links;
+
+	if (outarg->flags & FUSE_IOMAP_CONFIG_TIME) {
+		sb->s_time_gran = outarg->s_time_gran;
+		sb->s_time_min = outarg->s_time_min;
+		sb->s_time_max = outarg->s_time_max;
+	}
+
+	if (outarg->flags & FUSE_IOMAP_CONFIG_MAXBYTES)
+		sb->s_maxbytes = outarg->s_maxbytes;
+
+	return 0;
+}
+
+static void fuse_iomap_config_reply(struct fuse_mount *fm,
+				    struct fuse_args *args, int error)
+{
+	struct fuse_iomap_config_args *ia =
+		container_of(args, struct fuse_iomap_config_args, args);
 	struct fuse_conn *fc = fm->fc;
 	struct super_block *sb = fm->sb;
 	struct backing_dev_info *old_bdi = sb->s_bdi;
 	char *suffix = sb->s_bdev ? "-fuseblk" : "-fuse";
+	bool ok = true;
 	int res;
 
+	res = fuse_iomap_process_config(fm, error, &ia->outarg);
+	if (res) {
+		printk(KERN_ERR "%s: could not configure iomap, err=%d",
+		       sb->s_id, res);
+		ok = false;
+		goto done;
+	}
+
 	/*
 	 * sb->s_bdi points to the initial private bdi.  However, we want to
 	 * redirect it to a new private bdi with default dirty and readahead
@@ -741,6 +830,62 @@ void fuse_iomap_mount(struct fuse_mount *fm)
 	fc->sync_fs = true;
 	fc->iomap_conn.no_end = 0;
 	fc->iomap_conn.no_ioend = 0;
+
+done:
+	kfree(ia);
+	fuse_finish_init(fc, ok);
+}
+
+static struct fuse_iomap_config_args *
+fuse_iomap_new_mount(struct fuse_mount *fm)
+{
+	struct fuse_iomap_config_args *ia;
+
+	ia = kzalloc(sizeof(*ia), GFP_KERNEL | __GFP_NOFAIL);
+	ia->inarg.maxbytes = MAX_LFS_FILESIZE;
+	ia->inarg.flags = FUSE_IOMAP_CONFIG_ALL;
+
+	ia->args.opcode = FUSE_IOMAP_CONFIG;
+	ia->args.nodeid = 0;
+	ia->args.in_numargs = 1;
+	ia->args.in_args[0].size = sizeof(ia->inarg);
+	ia->args.in_args[0].value = &ia->inarg;
+	ia->args.out_argvar = true;
+	ia->args.out_numargs = 1;
+	ia->args.out_args[0].size = sizeof(ia->outarg);
+	ia->args.out_args[0].value = &ia->outarg;
+	ia->args.force = true;
+	ia->args.nocreds = true;
+
+	return ia;
+}
+
+int fuse_iomap_mount(struct fuse_mount *fm)
+{
+	struct fuse_iomap_config_args *ia = fuse_iomap_new_mount(fm);
+	int err;
+
+	ASSERT(fm->fc->sync_init);
+
+	err = fuse_simple_request(fm, &ia->args);
+	/* Ignore size of iomap_config reply */
+	if (err > 0)
+		err = 0;
+	fuse_iomap_config_reply(fm, &ia->args, err);
+	return err;
+}
+
+void fuse_iomap_mount_async(struct fuse_mount *fm)
+{
+	struct fuse_iomap_config_args *ia = fuse_iomap_new_mount(fm);
+	int err;
+
+	ASSERT(!fm->fc->sync_init);
+
+	ia->args.end = fuse_iomap_config_reply;
+	err = fuse_simple_background(fm, &ia->args, GFP_KERNEL);
+	if (err)
+		fuse_iomap_config_reply(fm, &ia->args, -ENOTCONN);
 }
 
 void fuse_iomap_unmount(struct fuse_mount *fm)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 4f348fc575a5c3..beb9ee62b6b861 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1319,6 +1319,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
 	struct fuse_init_out *arg = &ia->out;
 	bool ok = true;
 
+	atomic_inc(&fc->need_init);
+
 	if (error || arg->major != FUSE_KERNEL_VERSION)
 		ok = false;
 	else {
@@ -1466,9 +1468,6 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
 
 		init_server_timeout(fc, timeout);
 
-		if (fc->iomap)
-			fuse_iomap_mount(fm);
-
 		fm->sb->s_bdi->ra_pages =
 				min(fm->sb->s_bdi->ra_pages, ra_pages);
 		fc->minor = arg->minor;
@@ -1478,13 +1477,27 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
 	}
 	kfree(ia);
 
-	if (!ok) {
+	if (!ok)
 		fc->conn_init = 0;
+
+	if (ok && fc->iomap) {
+		atomic_inc(&fc->need_init);
+		if (!fc->sync_init)
+			fuse_iomap_mount_async(fm);
+	}
+
+	fuse_finish_init(fc, ok);
+}
+
+void fuse_finish_init(struct fuse_conn *fc, bool ok)
+{
+	if (!ok)
 		fc->conn_error = 1;
-	}
 
-	fuse_set_initialized(fc);
-	wake_up_all(&fc->blocked_waitq);
+	if (atomic_dec_and_test(&fc->need_init)) {
+		fuse_set_initialized(fc);
+		wake_up_all(&fc->blocked_waitq);
+	}
 }
 
 static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
@@ -1974,7 +1987,20 @@ static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc)
 
 	fm = get_fuse_mount_super(sb);
 
-	return fuse_send_init(fm);
+	err = fuse_send_init(fm);
+	if (err)
+		return err;
+
+	if (fm->fc->conn_init && fm->fc->sync_init && fm->fc->iomap) {
+		err = fuse_iomap_mount(fm);
+		if (err)
+			return err;
+	}
+
+	if (fm->fc->conn_error)
+		return -EIO;
+
+	return 0;
 }
 
 /*

[PATCH 20/28] fuse_trace: query filesystem geometry when using iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |    3 +++
 2 files changed, 51 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index e69ad48b14066b..66b564bcd25360 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -58,6 +58,7 @@
 	EM( FUSE_SYNCFS,		"FUSE_SYNCFS")		\
 	EM( FUSE_TMPFILE,		"FUSE_TMPFILE")		\
 	EM( FUSE_STATX,			"FUSE_STATX")		\
+	EM( FUSE_IOMAP_CONFIG,		"FUSE_IOMAP_CONFIG")	\
 	EM( FUSE_IOMAP_BEGIN,		"FUSE_IOMAP_BEGIN")	\
 	EM( FUSE_IOMAP_END,		"FUSE_IOMAP_END")	\
 	EM( FUSE_IOMAP_IOEND,		"FUSE_IOMAP_IOEND")	\
@@ -340,6 +341,14 @@ TRACE_DEFINE_ENUM(FUSE_I_IOMAP);
 	{ IOMAP_IOEND_BOUNDARY,			"boundary" }, \
 	{ IOMAP_IOEND_DIRECT,			"direct" }
 
+#define FUSE_IOMAP_CONFIG_STRINGS \
+	{ FUSE_IOMAP_CONFIG_SID,		"sid" }, \
+	{ FUSE_IOMAP_CONFIG_UUID,		"uuid" }, \
+	{ FUSE_IOMAP_CONFIG_BLOCKSIZE,		"blocksize" }, \
+	{ FUSE_IOMAP_CONFIG_MAX_LINKS,		"max_links" }, \
+	{ FUSE_IOMAP_CONFIG_TIME,		"time" }, \
+	{ FUSE_IOMAP_CONFIG_MAXBYTES,		"maxbytes" }
+
 DECLARE_EVENT_CLASS(fuse_iomap_check_class,
 	TP_PROTO(const char *func, int line, const char *condition),
 
@@ -968,6 +977,45 @@ TRACE_EVENT(fuse_iomap_fallocate,
 		  __entry->mode,
 		  __entry->newsize)
 );
+
+TRACE_EVENT(fuse_iomap_config,
+	TP_PROTO(const struct fuse_mount *fm,
+		 const struct fuse_iomap_config_out *outarg),
+	TP_ARGS(fm, outarg),
+
+	TP_STRUCT__entry(
+		__field(dev_t,			connection)
+
+		__field(uint32_t,		flags)
+		__field(uint32_t,		blocksize)
+		__field(uint32_t,		max_links)
+		__field(uint32_t,		time_gran)
+
+		__field(int64_t,		time_min)
+		__field(int64_t,		time_max)
+		__field(int64_t,		maxbytes)
+		__field(uint8_t,		uuid_len)
+	),
+
+	TP_fast_assign(
+		__entry->connection	=	fm->fc->dev;
+		__entry->flags		=	outarg->flags;
+		__entry->blocksize	=	outarg->s_blocksize;
+		__entry->max_links	=	outarg->s_max_links;
+		__entry->time_gran	=	outarg->s_time_gran;
+		__entry->time_min	=	outarg->s_time_min;
+		__entry->time_max	=	outarg->s_time_max;
+		__entry->maxbytes	=	outarg->s_maxbytes;
+		__entry->uuid_len	=	outarg->s_uuid_len;
+	),
+
+	TP_printk("connection %u flags (%s) blocksize 0x%x max_links %u time_gran %u time_min %lld time_max %lld maxbytes 0x%llx uuid_len %u",
+		  __entry->connection,
+		  __print_flags(__entry->flags, "|", FUSE_IOMAP_CONFIG_STRINGS),
+		  __entry->blocksize, __entry->max_links, __entry->time_gran,
+		  __entry->time_min, __entry->time_max, __entry->maxbytes,
+		  __entry->uuid_len)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index abba22107718d9..2d01828fc532b0 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -735,6 +735,8 @@ static int fuse_iomap_process_config(struct fuse_mount *fm, int error,
 		return error;
 	}
 
+	trace_fuse_iomap_config(fm, outarg);
+
 	if (outarg->flags & ~FUSE_IOMAP_CONFIG_ALL)
 		return -EINVAL;
 
@@ -760,6 +762,7 @@ static int fuse_iomap_process_config(struct fuse_mount *fm, int error,
 			sb->s_blocksize = outarg->s_blocksize;
 			sb->s_blocksize_bits = blksize_bits(outarg->s_blocksize);
 		}
+		fm->fc->blkbits = sb->s_blocksize_bits;
 	}
 
 	if (outarg->flags & FUSE_IOMAP_CONFIG_SID)

[PATCH 21/28] fuse: implement fadvise for iomap files

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

If userspace asks us to perform readahead on a file, take i_rwsem so
that it can't race with hole punching or writes.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h     |    3 +++
 fs/fuse/file.c       |    1 +
 fs/fuse/file_iomap.c |   20 ++++++++++++++++++++
 3 files changed, 24 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index e45780f6fe9e39..d59c19f61d5337 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1789,6 +1789,8 @@ int fuse_iomap_flush_unmap_range(struct inode *inode, loff_t pos,
 
 int fuse_dev_ioctl_iomap_support(struct file *file,
 				 struct fuse_iomap_support __user *argp);
+
+int fuse_iomap_fadvise(struct file *file, loff_t start, loff_t end, int advice);
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
@@ -1813,6 +1815,7 @@ int fuse_dev_ioctl_iomap_support(struct file *file,
 # define fuse_iomap_fallocate(...)		(-ENOSYS)
 # define fuse_iomap_flush_unmap_range(...)	(-ENOSYS)
 # define fuse_dev_ioctl_iomap_support(...)	(-EOPNOTSUPP)
+# define fuse_iomap_fadvise			NULL
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index dd65485c9743bf..9476f14035bb7f 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3189,6 +3189,7 @@ static const struct file_operations fuse_file_operations = {
 	.poll		= fuse_file_poll,
 	.fallocate	= fuse_file_fallocate,
 	.copy_file_range = fuse_copy_file_range,
+	.fadvise	= fuse_iomap_fadvise,
 };
 
 static const struct address_space_operations fuse_file_aops  = {
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 2d01828fc532b0..a484cd235d9da2 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -7,6 +7,7 @@
 #include <linux/fiemap.h>
 #include <linux/pagemap.h>
 #include <linux/falloc.h>
+#include <linux/fadvise.h>
 #include "fuse_i.h"
 #include "fuse_trace.h"
 #include "iomap_priv.h"
@@ -1856,3 +1857,22 @@ int fuse_dev_ioctl_iomap_support(struct file *file,
 		return -EFAULT;
 	return 0;
 }
+
+int fuse_iomap_fadvise(struct file *file, loff_t start, loff_t end, int advice)
+{
+	struct inode *inode = file_inode(file);
+	bool needlock = advice == POSIX_FADV_WILLNEED &&
+			fuse_inode_has_iomap(inode);
+	int ret;
+
+	/*
+	 * Operations creating pages in page cache need protection from hole
+	 * punching and similar ops
+	 */
+	if (needlock)
+		inode_lock_shared(inode);
+	ret = generic_fadvise(file, start, end, advice);
+	if (needlock)
+		inode_unlock_shared(inode);
+	return ret;
+}

[PATCH 22/28] fuse: invalidate ranges of block devices being used for iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Make it easier to invalidate the page cache for a block device that is
being used in conjunction with iomap.  This allows a fuse server to kill
all cached data for a block that is being freed, so that block reuse
doesn't result in file corruption.  Right now, the only way to do this
is with fadvise, which ignores and doesn't wait for pages undergoing
writeback.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |    3 +++
 include/uapi/linux/fuse.h |   10 ++++++++++
 fs/fuse/dev.c             |   27 +++++++++++++++++++++++++++
 fs/fuse/file_iomap.c      |   40 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 80 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index d59c19f61d5337..4aa7199dd0cd9f 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1789,6 +1789,8 @@ int fuse_iomap_flush_unmap_range(struct inode *inode, loff_t pos,
 
 int fuse_dev_ioctl_iomap_support(struct file *file,
 				 struct fuse_iomap_support __user *argp);
+int fuse_iomap_dev_inval(struct fuse_conn *fc,
+			 const struct fuse_iomap_dev_inval_out *arg);
 
 int fuse_iomap_fadvise(struct file *file, loff_t start, loff_t end, int advice);
 #else
@@ -1815,6 +1817,7 @@ int fuse_iomap_fadvise(struct file *file, loff_t start, loff_t end, int advice);
 # define fuse_iomap_fallocate(...)		(-ENOSYS)
 # define fuse_iomap_flush_unmap_range(...)	(-ENOSYS)
 # define fuse_dev_ioctl_iomap_support(...)	(-EOPNOTSUPP)
+# define fuse_iomap_dev_inval(...)		(-ENOSYS)
 # define fuse_iomap_fadvise			NULL
 #endif
 
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 19c1ac5006faa9..b63fba0a2c52c9 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -240,6 +240,7 @@
  *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
  *  - add FUSE_ATTR_IOMAP to enable iomap for specific inodes
  *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
+ *  - add FUSE_NOTIFY_IOMAP_DEV_INVAL to invalidate iomap bdev ranges
  */
 
 #ifndef _LINUX_FUSE_H
@@ -689,6 +690,7 @@ enum fuse_notify_code {
 	FUSE_NOTIFY_DELETE = 6,
 	FUSE_NOTIFY_RESEND = 7,
 	FUSE_NOTIFY_INC_EPOCH = 8,
+	FUSE_NOTIFY_IOMAP_DEV_INVAL = 9,
 	FUSE_NOTIFY_CODE_MAX,
 };
 
@@ -1464,4 +1466,12 @@ struct fuse_iomap_config_out {
 	int64_t s_maxbytes;	/* max file size */
 };
 
+struct fuse_iomap_dev_inval_out {
+	uint32_t dev;		/* device cookie */
+	uint32_t reserved;	/* zero */
+
+	uint64_t offset;	/* range to invalidate pagecache, bytes */
+	uint64_t length;
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index bb0ec19a368bea..adbe2a65e6fe87 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1868,6 +1868,30 @@ static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
 	return err;
 }
 
+static int fuse_notify_iomap_dev_inval(struct fuse_conn *fc, unsigned int size,
+				       struct fuse_copy_state *cs)
+{
+	struct fuse_iomap_dev_inval_out outarg;
+	int err = -EINVAL;
+
+	if (size != sizeof(outarg))
+		goto err;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto err;
+	if (outarg.reserved) {
+		err = -EINVAL;
+		goto err;
+	}
+	fuse_copy_finish(cs);
+
+	return fuse_iomap_dev_inval(fc, &outarg);
+err:
+	fuse_copy_finish(cs);
+	return err;
+}
+
 struct fuse_retrieve_args {
 	struct fuse_args_pages ap;
 	struct fuse_notify_retrieve_in inarg;
@@ -2114,6 +2138,9 @@ static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
 	case FUSE_NOTIFY_INC_EPOCH:
 		return fuse_notify_inc_epoch(fc);
 
+	case FUSE_NOTIFY_IOMAP_DEV_INVAL:
+		return fuse_notify_iomap_dev_inval(fc, size, cs);
+
 	default:
 		fuse_copy_finish(cs);
 		return -EINVAL;
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index a484cd235d9da2..9c798435e45633 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1876,3 +1876,43 @@ int fuse_iomap_fadvise(struct file *file, loff_t start, loff_t end, int advice)
 		inode_unlock_shared(inode);
 	return ret;
 }
+
+int fuse_iomap_dev_inval(struct fuse_conn *fc,
+			 const struct fuse_iomap_dev_inval_out *arg)
+{
+	struct fuse_backing *fb;
+	struct block_device *bdev;
+	loff_t end;
+	int ret = 0;
+
+	if (!fc->iomap || arg->dev == FUSE_IOMAP_DEV_NULL)
+		return -EINVAL;
+
+	down_read(&fc->killsb);
+	fb = fuse_backing_lookup(fc, &fuse_iomap_backing_ops, arg->dev);
+	if (!fb) {
+		ret = -ENODEV;
+		goto out_killsb;
+	}
+	bdev = fb->bdev;
+
+	inode_lock(bdev->bd_mapping->host);
+	filemap_invalidate_lock(bdev->bd_mapping);
+
+	if (check_add_overflow(arg->offset, arg->length, &end) ||
+	    arg->offset >= bdev_nr_bytes(bdev)) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	end = min(end, bdev_nr_bytes(bdev));
+	truncate_inode_pages_range(bdev->bd_mapping, arg->offset, end - 1);
+
+out_unlock:
+	filemap_invalidate_unlock(bdev->bd_mapping);
+	inode_unlock(bdev->bd_mapping->host);
+	fuse_backing_put(fb);
+out_killsb:
+	up_read(&fc->killsb);
+	return ret;
+}

[PATCH 23/28] fuse_trace: invalidate ranges of block devices being used for iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   26 ++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |    2 ++
 2 files changed, 28 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 66b564bcd25360..1cff42bc5907bf 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -1016,6 +1016,32 @@ TRACE_EVENT(fuse_iomap_config,
 		  __entry->time_min, __entry->time_max, __entry->maxbytes,
 		  __entry->uuid_len)
 );
+
+TRACE_EVENT(fuse_iomap_dev_inval,
+	TP_PROTO(const struct fuse_conn *fc,
+		 const struct fuse_iomap_dev_inval_out *arg),
+	TP_ARGS(fc, arg),
+
+	TP_STRUCT__entry(
+		__field(dev_t,			connection)
+		__field(int,			dev)
+		__field(unsigned long long,	offset)
+		__field(unsigned long long,	length)
+	),
+
+	TP_fast_assign(
+		__entry->connection	=	fc->dev;
+		__entry->dev		=	arg->dev;
+		__entry->offset		=	arg->offset;
+		__entry->length		=	arg->length;
+	),
+
+	TP_printk("connection %u dev %d offset 0x%llx length 0x%llx",
+		  __entry->connection,
+		  __entry->dev,
+		  __entry->offset,
+		  __entry->length)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 9c798435e45633..d2945f8071a296 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1885,6 +1885,8 @@ int fuse_iomap_dev_inval(struct fuse_conn *fc,
 	loff_t end;
 	int ret = 0;
 
+	trace_fuse_iomap_dev_inval(fc, arg);
+
 	if (!fc->iomap || arg->dev == FUSE_IOMAP_DEV_NULL)
 		return -EINVAL;
 

[PATCH 24/28] fuse: implement inline data file IO via iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Implement inline data file IO by issuing FUSE_READ/FUSE_WRITE commands
in response to an inline data mapping.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/file_iomap.c |  184 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 184 insertions(+)


diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index d2945f8071a296..8faf16f58df035 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -417,6 +417,150 @@ fuse_iomap_find_dev(struct fuse_conn *fc, const struct fuse_iomap_io *map)
 	return ret;
 }
 
+static inline int fuse_iomap_inline_alloc(struct iomap *iomap)
+{
+	ASSERT(iomap->inline_data == NULL);
+	ASSERT(iomap->length > 0);
+
+	iomap->inline_data = kvzalloc(iomap->length, GFP_KERNEL);
+	return iomap->inline_data ? 0 : -ENOMEM;
+}
+
+static inline void fuse_iomap_inline_free(struct iomap *iomap)
+{
+	kvfree(iomap->inline_data);
+	iomap->inline_data = NULL;
+}
+
+/*
+ * Use the FUSE_READ command to read inline file data from the fuse server.
+ * Note that there's no file handle attached, so the fuse server must be able
+ * to reconnect to the inode via the nodeid.
+ */
+static int fuse_iomap_inline_read(struct inode *inode, loff_t pos,
+				  loff_t count, struct iomap *iomap)
+{
+	struct fuse_read_in in = {
+		.offset = pos,
+		.size = count,
+	};
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_mount *fm = get_fuse_mount(inode);
+	FUSE_ARGS(args);
+	ssize_t ret;
+
+	if (BAD_DATA(!iomap_inline_data_valid(iomap)))
+		return -EFSCORRUPTED;
+
+	args.opcode = FUSE_READ;
+	args.nodeid = fi->nodeid;
+	args.in_numargs = 1;
+	args.in_args[0].size = sizeof(in);
+	args.in_args[0].value = &in;
+	args.out_argvar = true;
+	args.out_numargs = 1;
+	args.out_args[0].size = count;
+	args.out_args[0].value = iomap_inline_data(iomap, pos);
+
+	ret = fuse_simple_request(fm, &args);
+	if (ret < 0) {
+		fuse_iomap_inline_free(iomap);
+		return ret;
+	}
+	/* no readahead means something bad happened */
+	if (ret == 0) {
+		fuse_iomap_inline_free(iomap);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/*
+ * Use the FUSE_WRITE command to write inline file data from the fuse server.
+ * Note that there's no file handle attached, so the fuse server must be able
+ * to reconnect to the inode via the nodeid.
+ */
+static int fuse_iomap_inline_write(struct inode *inode, loff_t pos,
+				   loff_t count, struct iomap *iomap)
+{
+	struct fuse_write_in in = {
+		.offset = pos,
+		.size = count,
+	};
+	struct fuse_write_out out = { };
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_mount *fm = get_fuse_mount(inode);
+	FUSE_ARGS(args);
+	ssize_t ret;
+
+	if (BAD_DATA(!iomap_inline_data_valid(iomap)))
+		return -EFSCORRUPTED;
+
+	args.opcode = FUSE_WRITE;
+	args.nodeid = fi->nodeid;
+	args.in_numargs = 2;
+	args.in_args[0].size = sizeof(in);
+	args.in_args[0].value = &in;
+	args.in_args[1].size = count;
+	args.in_args[1].value = iomap_inline_data(iomap, pos);
+	args.out_numargs = 1;
+	args.out_args[0].size = sizeof(out);
+	args.out_args[0].value = &out;
+
+	ret = fuse_simple_request(fm, &args);
+	if (ret < 0) {
+		fuse_iomap_inline_free(iomap);
+		return ret;
+	}
+	/* short write means something bad happened */
+	if (out.size < count) {
+		fuse_iomap_inline_free(iomap);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/* Set up inline data buffers for iomap_begin */
+static int fuse_iomap_set_inline(struct inode *inode, unsigned opflags,
+				 loff_t pos, loff_t count,
+				 struct iomap *iomap, struct iomap *srcmap)
+{
+	int err;
+
+	if (opflags & IOMAP_REPORT)
+		return 0;
+
+	if (fuse_is_iomap_file_write(opflags)) {
+		if (iomap->type == IOMAP_INLINE) {
+			err = fuse_iomap_inline_alloc(iomap);
+			if (err)
+				return err;
+		}
+
+		if (srcmap->type == IOMAP_INLINE) {
+			err = fuse_iomap_inline_alloc(srcmap);
+			if (!err)
+				err = fuse_iomap_inline_read(inode, pos, count,
+							     srcmap);
+			if (err) {
+				fuse_iomap_inline_free(iomap);
+				return err;
+			}
+		}
+	} else if (iomap->type == IOMAP_INLINE) {
+		/* inline data read */
+		err = fuse_iomap_inline_alloc(iomap);
+		if (!err)
+			err = fuse_iomap_inline_read(inode, pos, count, iomap);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 			    unsigned opflags, struct iomap *iomap,
 			    struct iomap *srcmap)
@@ -486,12 +630,20 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 		fuse_iomap_from_server(inode, iomap, read_dev, &outarg.read);
 	}
 
+	if (iomap->type == IOMAP_INLINE || srcmap->type == IOMAP_INLINE) {
+		err = fuse_iomap_set_inline(inode, opflags, pos, count, iomap,
+					    srcmap);
+		if (err)
+			goto out_write_dev;
+	}
+
 	/*
 	 * XXX: if we ever want to support closing devices, we need a way to
 	 * track the fuse_backing refcount all the way through bio endios.
 	 * For now we put the refcount here because you can't remove an iomap
 	 * device until unmount time.
 	 */
+out_write_dev:
 	fuse_backing_put(write_dev);
 out_read_dev:
 	fuse_backing_put(read_dev);
@@ -530,8 +682,28 @@ static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t count,
 {
 	struct fuse_inode *fi = get_fuse_inode(inode);
 	struct fuse_mount *fm = get_fuse_mount(inode);
+	struct iomap_iter *iter = container_of(iomap, struct iomap_iter, iomap);
+	struct iomap *srcmap = &iter->srcmap;
 	int err = 0;
 
+	if (srcmap->inline_data)
+		fuse_iomap_inline_free(srcmap);
+
+	if (iomap->inline_data) {
+		if (fuse_is_iomap_file_write(opflags) && written > 0) {
+			err = fuse_iomap_inline_write(inode, pos, written,
+						      iomap);
+			fuse_iomap_inline_free(iomap);
+			if (err)
+				return err;
+		} else {
+			fuse_iomap_inline_free(iomap);
+		}
+
+		/* fuse server should already be aware of what happened */
+		return 0;
+	}
+
 	if (fuse_should_send_iomap_end(fm, iomap, opflags, count, written)) {
 		struct fuse_iomap_end_in inarg = {
 			.opflags = fuse_iomap_op_to_server(opflags),
@@ -1431,6 +1603,18 @@ static ssize_t fuse_iomap_writeback_range(struct iomap_writepage_ctx *wpc,
 		if (ret)
 			goto discard_folio;
 
+		if (BAD_DATA(write_iomap.type == IOMAP_INLINE)) {
+			/*
+			 * iomap assumes that inline data writes are completed
+			 * by the time ->iomap_end completes, so it should
+			 * never mark a pagecache folio dirty.
+			 */
+			fuse_iomap_end(inode, offset, len, 0,
+				       FUSE_IOMAP_OP_WRITEBACK, &write_iomap);
+			ret = -EIO;
+			goto discard_folio;
+		}
+
 		/*
 		 * Landed in a hole or beyond EOF?  Send that to iomap, it'll
 		 * skip writing back the file range.

[PATCH 25/28] fuse_trace: implement inline data file IO via iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   45 +++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |    7 +++++++
 2 files changed, 52 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 1cff42bc5907bf..b1c45abe40b440 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -227,6 +227,7 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 #if IS_ENABLED(CONFIG_FUSE_IOMAP)
 struct iomap_writepage_ctx;
 struct iomap_ioend;
+struct iomap;
 
 /* tracepoint boilerplate so we don't have to keep doing this */
 #define FUSE_IOMAP_OPFLAGS_FIELD \
@@ -1042,6 +1043,50 @@ TRACE_EVENT(fuse_iomap_dev_inval,
 		  __entry->offset,
 		  __entry->length)
 );
+
+DECLARE_EVENT_CLASS(fuse_iomap_inline_class,
+	TP_PROTO(const struct inode *inode, loff_t pos, uint64_t count,
+		 const struct iomap *map),
+	TP_ARGS(inode, pos, count, map),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		FUSE_IOMAP_MAP_FIELDS(map)
+		__field(bool,			has_buf)
+		__field(uint64_t,		validity_cookie)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	pos;
+		__entry->length		=	count;
+
+		__entry->mapdev		=	FUSE_IOMAP_DEV_NULL;
+		__entry->mapaddr	=	map->addr;
+		__entry->mapoffset	=	map->offset;
+		__entry->maplength	=	map->length;
+		__entry->maptype	=	map->type;
+		__entry->mapflags	=	map->flags;
+
+		__entry->has_buf	=	map->inline_data != NULL;
+		__entry->validity_cookie=	map->validity_cookie;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() FUSE_IOMAP_MAP_FMT() " has_buf? %d cookie 0x%llx",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map),
+		  __entry->has_buf,
+		  __entry->validity_cookie)
+);
+#define DEFINE_FUSE_IOMAP_INLINE_EVENT(name)	\
+DEFINE_EVENT(fuse_iomap_inline_class, name,	\
+	TP_PROTO(const struct inode *inode, loff_t pos, uint64_t count, \
+		 const struct iomap *map), \
+	TP_ARGS(inode, pos, count, map))
+DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_inline_read);
+DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_inline_write);
+DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_set_inline_iomap);
+DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_set_inline_srcmap);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 8faf16f58df035..a71de4ea5eb32d 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -452,6 +452,8 @@ static int fuse_iomap_inline_read(struct inode *inode, loff_t pos,
 	if (BAD_DATA(!iomap_inline_data_valid(iomap)))
 		return -EFSCORRUPTED;
 
+	trace_fuse_iomap_inline_read(inode, pos, count, iomap);
+
 	args.opcode = FUSE_READ;
 	args.nodeid = fi->nodeid;
 	args.in_numargs = 1;
@@ -497,6 +499,8 @@ static int fuse_iomap_inline_write(struct inode *inode, loff_t pos,
 	if (BAD_DATA(!iomap_inline_data_valid(iomap)))
 		return -EFSCORRUPTED;
 
+	trace_fuse_iomap_inline_write(inode, pos, count, iomap);
+
 	args.opcode = FUSE_WRITE;
 	args.nodeid = fi->nodeid;
 	args.in_numargs = 2;
@@ -558,6 +562,9 @@ static int fuse_iomap_set_inline(struct inode *inode, unsigned opflags,
 			return err;
 	}
 
+	trace_fuse_iomap_set_inline_iomap(inode, pos, count, iomap);
+	trace_fuse_iomap_set_inline_srcmap(inode, pos, count, srcmap);
+
 	return 0;
 }
 

[PATCH 26/28] fuse: allow more statx fields

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Allow the fuse server to supply us with the more recently added fields
of struct statx.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |    8 +++++
 include/uapi/linux/fuse.h |   15 ++++++++-
 fs/fuse/dir.c             |   75 ++++++++++++++++++++++++++++++++++++++-------
 3 files changed, 86 insertions(+), 12 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 4aa7199dd0cd9f..02af28f49cdfe5 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1733,6 +1733,14 @@ void fuse_iomap_sysfs_cleanup(struct kobject *kobj);
 
 sector_t fuse_bmap(struct address_space *mapping, sector_t block);
 
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
+int fuse_iomap_sysfs_init(struct kobject *kobj);
+void fuse_iomap_sysfs_cleanup(struct kobject *kobj);
+#else
+# define fuse_iomap_sysfs_init(...)		(0)
+# define fuse_iomap_sysfs_cleanup(...)		((void)0)
+#endif
+
 #if IS_ENABLED(CONFIG_FUSE_IOMAP)
 bool fuse_iomap_enabled(void);
 
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index b63fba0a2c52c9..e0139fb43f82ea 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -334,7 +334,20 @@ struct fuse_statx {
 	uint32_t	rdev_minor;
 	uint32_t	dev_major;
 	uint32_t	dev_minor;
-	uint64_t	__spare2[14];
+
+	uint64_t	mnt_id;
+	uint32_t	dio_mem_align;
+	uint32_t	dio_offset_align;
+	uint64_t	subvol;
+
+	uint32_t	atomic_write_unit_min;
+	uint32_t	atomic_write_unit_max;
+	uint32_t	atomic_write_segments_max;
+	uint32_t	dio_read_offset_align;
+	uint32_t	atomic_write_unit_max_opt;
+	uint32_t	__spare2[1];
+
+	uint64_t	__spare3[8];
 };
 
 struct fuse_kstatfs {
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index d62ceadbc05fb2..b5e3536f1d53c1 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1274,6 +1274,50 @@ static void fuse_statx_to_attr(struct fuse_statx *sx, struct fuse_attr *attr)
 	attr->blksize = sx->blksize;
 }
 
+#define FUSE_SUPPORTED_STATX_MASK	(STATX_BASIC_STATS | \
+					 STATX_BTIME | \
+					 STATX_DIOALIGN | \
+					 STATX_SUBVOL | \
+					 STATX_WRITE_ATOMIC)
+
+#define FUSE_UNCACHED_STATX_MASK	(STATX_DIOALIGN | \
+					 STATX_SUBVOL | \
+					 STATX_WRITE_ATOMIC)
+
+static void kstat_from_fuse_statx(const struct fuse_conn *fc,
+				  struct kstat *stat,
+				  const struct fuse_statx *sx)
+{
+	stat->result_mask = sx->mask & FUSE_SUPPORTED_STATX_MASK;
+
+	stat->attributes |= fuse_statx_attributes(fc, sx);
+	stat->attributes_mask |= fuse_statx_attributes_mask(fc, sx);
+
+	if (sx->mask & STATX_BTIME) {
+		stat->btime.tv_sec = sx->btime.tv_sec;
+		stat->btime.tv_nsec = min_t(u32, sx->btime.tv_nsec,
+					    NSEC_PER_SEC - 1);
+	}
+
+	if (sx->mask & STATX_DIOALIGN) {
+		stat->dio_mem_align = sx->dio_mem_align;
+		stat->dio_offset_align = sx->dio_offset_align;
+	}
+
+	if (sx->mask & STATX_SUBVOL)
+		stat->subvol = sx->subvol;
+
+	if (sx->mask & STATX_WRITE_ATOMIC) {
+		stat->atomic_write_unit_min = sx->atomic_write_unit_min;
+		stat->atomic_write_unit_max = sx->atomic_write_unit_max;
+		stat->atomic_write_unit_max_opt = sx->atomic_write_unit_max_opt;
+		stat->atomic_write_segments_max = sx->atomic_write_segments_max;
+	}
+
+	if (sx->mask & STATX_DIO_READ_ALIGN)
+		stat->dio_read_offset_align = sx->dio_read_offset_align;
+}
+
 static int fuse_do_statx(struct mnt_idmap *idmap, struct inode *inode,
 			 struct file *file, struct kstat *stat)
 {
@@ -1297,7 +1341,7 @@ static int fuse_do_statx(struct mnt_idmap *idmap, struct inode *inode,
 	}
 	/* For now leave sync hints as the default, request all stats. */
 	inarg.sx_flags = 0;
-	inarg.sx_mask = STATX_BASIC_STATS | STATX_BTIME;
+	inarg.sx_mask = FUSE_SUPPORTED_STATX_MASK;
 	args.opcode = FUSE_STATX;
 	args.nodeid = get_node_id(inode);
 	args.in_numargs = 1;
@@ -1325,11 +1369,7 @@ static int fuse_do_statx(struct mnt_idmap *idmap, struct inode *inode,
 	}
 
 	if (stat) {
-		stat->result_mask = sx->mask & (STATX_BASIC_STATS | STATX_BTIME);
-		stat->btime.tv_sec = sx->btime.tv_sec;
-		stat->btime.tv_nsec = min_t(u32, sx->btime.tv_nsec, NSEC_PER_SEC - 1);
-		stat->attributes |= fuse_statx_attributes(fm->fc, sx);
-		stat->attributes_mask |= fuse_statx_attributes_mask(fm->fc, sx);
+		kstat_from_fuse_statx(fm->fc, stat, sx);
 		fuse_fillattr(idmap, inode, &attr, stat);
 		stat->result_mask |= STATX_TYPE;
 	}
@@ -1394,16 +1434,29 @@ static int fuse_update_get_attr(struct mnt_idmap *idmap, struct inode *inode,
 	u32 inval_mask = READ_ONCE(fi->inval_mask);
 	u32 cache_mask = fuse_get_cache_mask(inode);
 
-
-	/* FUSE only supports basic stats and possibly btime */
-	request_mask &= STATX_BASIC_STATS | STATX_BTIME;
+	/* Only ask for supported stats */
+	request_mask &= FUSE_SUPPORTED_STATX_MASK;
 retry:
 	if (fc->no_statx)
 		request_mask &= STATX_BASIC_STATS;
 
 	if (!request_mask)
 		sync = false;
-	else if (flags & AT_STATX_FORCE_SYNC)
+	else if (request_mask & FUSE_UNCACHED_STATX_MASK) {
+		switch (flags & AT_STATX_SYNC_TYPE) {
+		case AT_STATX_DONT_SYNC:
+			request_mask &= ~FUSE_UNCACHED_STATX_MASK;
+			sync = false;
+			break;
+		case AT_STATX_FORCE_SYNC:
+		case AT_STATX_SYNC_AS_STAT:
+			sync = true;
+			break;
+		default:
+			WARN_ON(1);
+			break;
+		}
+	} else if (flags & AT_STATX_FORCE_SYNC)
 		sync = true;
 	else if (flags & AT_STATX_DONT_SYNC)
 		sync = false;
@@ -1414,7 +1467,7 @@ static int fuse_update_get_attr(struct mnt_idmap *idmap, struct inode *inode,
 
 	if (sync) {
 		forget_all_cached_acls(inode);
-		/* Try statx if BTIME is requested */
+		/* Try statx if a field not covered by regular stat is wanted */
 		if (!fc->no_statx && (request_mask & ~STATX_BASIC_STATS)) {
 			err = fuse_do_statx(idmap, inode, file, stat);
 			if (err == -ENOSYS) {

[PATCH 27/28] fuse: support atomic writes with iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

One whole block!

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |    9 ++++++++
 fs/fuse/fuse_trace.h      |    4 +++-
 include/uapi/linux/fuse.h |    5 +++++
 fs/fuse/file_iomap.c      |   50 ++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 66 insertions(+), 2 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 02af28f49cdfe5..777826115d3e80 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -259,6 +259,8 @@ enum {
 	FUSE_I_CACHE_IO_MODE,
 	/* Use iomap for this inode */
 	FUSE_I_IOMAP,
+	/* Enable untorn writes */
+	FUSE_I_ATOMIC,
 };
 
 struct fuse_conn;
@@ -1765,6 +1767,13 @@ static inline bool fuse_inode_has_iomap(const struct inode *inode)
 	return test_bit(FUSE_I_IOMAP, &fi->state);
 }
 
+static inline bool fuse_inode_has_atomic(const struct inode *inode)
+{
+	const struct fuse_inode *fi = get_fuse_inode_c(inode);
+
+	return test_bit(FUSE_I_ATOMIC, &fi->state);
+}
+
 int fuse_iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		      u64 start, u64 length);
 loff_t fuse_iomap_lseek(struct file *file, loff_t offset, int whence);
diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index b1c45abe40b440..1befea65d4b15c 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -326,6 +326,7 @@ TRACE_DEFINE_ENUM(FUSE_I_BAD);
 TRACE_DEFINE_ENUM(FUSE_I_BTIME);
 TRACE_DEFINE_ENUM(FUSE_I_CACHE_IO_MODE);
 TRACE_DEFINE_ENUM(FUSE_I_IOMAP);
+TRACE_DEFINE_ENUM(FUSE_I_ATOMIC);
 
 #define FUSE_IFLAG_STRINGS \
 	{ 1 << FUSE_I_ADVISE_RDPLUS,		"advise_rdplus" }, \
@@ -334,7 +335,8 @@ TRACE_DEFINE_ENUM(FUSE_I_IOMAP);
 	{ 1 << FUSE_I_BAD,			"bad" }, \
 	{ 1 << FUSE_I_BTIME,			"btime" }, \
 	{ 1 << FUSE_I_CACHE_IO_MODE,		"cacheio" }, \
-	{ 1 << FUSE_I_IOMAP,			"iomap" }
+	{ 1 << FUSE_I_IOMAP,			"iomap" }, \
+	{ 1 << FUSE_I_ATOMIC,			"atomic" }
 
 #define IOMAP_IOEND_STRINGS \
 	{ IOMAP_IOEND_SHARED,			"shared" }, \
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index e0139fb43f82ea..472605d7ff6a2f 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -241,6 +241,7 @@
  *  - add FUSE_ATTR_IOMAP to enable iomap for specific inodes
  *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
  *  - add FUSE_NOTIFY_IOMAP_DEV_INVAL to invalidate iomap bdev ranges
+ *  - add FUSE_ATTR_ATOMIC for single-fsblock atomic write support
  */
 
 #ifndef _LINUX_FUSE_H
@@ -595,10 +596,12 @@ struct fuse_file_lock {
  * FUSE_ATTR_SUBMOUNT: Object is a submount root
  * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
  * FUSE_ATTR_IOMAP: Use iomap for this inode
+ * FUSE_ATTR_ATOMIC: Enable untorn writes
  */
 #define FUSE_ATTR_SUBMOUNT      (1 << 0)
 #define FUSE_ATTR_DAX		(1 << 1)
 #define FUSE_ATTR_IOMAP		(1 << 2)
+#define FUSE_ATTR_ATOMIC	(1 << 3)
 
 /**
  * Open flags
@@ -1158,6 +1161,8 @@ struct fuse_backing_map {
 
 /* basic file I/O functionality through iomap */
 #define FUSE_IOMAP_SUPPORT_FILEIO	(1ULL << 0)
+/* untorn writes through iomap */
+#define FUSE_IOMAP_SUPPORT_ATOMIC	(1ULL << 1)
 struct fuse_iomap_support {
 	uint64_t	flags;
 	uint64_t	padding;
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index a71de4ea5eb32d..30db4079ab8a55 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1099,12 +1099,32 @@ static inline void fuse_inode_clear_iomap(struct inode *inode)
 	clear_bit(FUSE_I_IOMAP, &fi->state);
 }
 
+static inline void fuse_inode_set_atomic(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	set_bit(FUSE_I_ATOMIC, &fi->state);
+}
+
+static inline void fuse_inode_clear_atomic(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	clear_bit(FUSE_I_ATOMIC, &fi->state);
+}
+
 void fuse_iomap_init_inode(struct inode *inode, unsigned attr_flags)
 {
 	struct fuse_conn *conn = get_fuse_conn(inode);
 
 	if (conn->iomap && (attr_flags & FUSE_ATTR_IOMAP))
 		fuse_inode_set_iomap(inode);
+	if (fuse_inode_has_iomap(inode) && (attr_flags & FUSE_ATTR_ATOMIC))
+		fuse_inode_set_atomic(inode);
 
 	trace_fuse_iomap_init_inode(inode);
 }
@@ -1113,6 +1133,8 @@ void fuse_iomap_evict_inode(struct inode *inode)
 {
 	trace_fuse_iomap_evict_inode(inode);
 
+	if (fuse_inode_has_atomic(inode))
+		fuse_inode_clear_atomic(inode);
 	if (fuse_inode_has_iomap(inode))
 		fuse_inode_clear_iomap(inode);
 }
@@ -1191,6 +1213,8 @@ void fuse_iomap_open(struct inode *inode, struct file *file)
 	ASSERT(fuse_inode_has_iomap(inode));
 
 	file->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
+	if (fuse_inode_has_atomic(inode))
+		file->f_mode |= FMODE_CAN_ATOMIC_WRITE;
 }
 
 enum fuse_ilock_type {
@@ -1397,6 +1421,17 @@ fuse_iomap_write_checks(
 	return kiocb_modified(iocb);
 }
 
+static inline ssize_t fuse_iomap_atomic_write_valid(struct kiocb *iocb,
+						    struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+
+	if (iov_iter_count(from) != i_blocksize(inode))
+		return -EINVAL;
+
+	return generic_atomic_write_valid(iocb, from);
+}
+
 ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from)
 {
 	struct inode *inode = file_inode(iocb->ki_filp);
@@ -1412,6 +1447,12 @@ ssize_t fuse_iomap_direct_write(struct kiocb *iocb, struct iov_iter *from)
 	if (!count)
 		return 0;
 
+	if (iocb->ki_flags & IOCB_ATOMIC) {
+		ret = fuse_iomap_atomic_write_valid(iocb, from);
+		if (ret)
+			return ret;
+	}
+
 	/*
 	 * Unaligned direct writes require zeroing of unwritten head and tail
 	 * blocks.  Extending writes require zeroing of post-EOF tail blocks.
@@ -1819,6 +1860,12 @@ ssize_t fuse_iomap_buffered_write(struct kiocb *iocb, struct iov_iter *from)
 	if (!iov_iter_count(from))
 		return 0;
 
+	if (iocb->ki_flags & IOCB_ATOMIC) {
+		ret = fuse_iomap_atomic_write_valid(iocb, from);
+		if (ret)
+			return ret;
+	}
+
 	ret = fuse_iomap_ilock_iocb(iocb, EXCL);
 	if (ret)
 		return ret;
@@ -2042,7 +2089,8 @@ int fuse_dev_ioctl_iomap_support(struct file *file,
 	struct fuse_iomap_support ios = { };
 
 	if (fuse_iomap_enabled())
-		ios.flags = FUSE_IOMAP_SUPPORT_FILEIO;
+		ios.flags = FUSE_IOMAP_SUPPORT_FILEIO |
+			    FUSE_IOMAP_SUPPORT_ATOMIC;
 
 	if (copy_to_user(argp, &ios, sizeof(ios)))
 		return -EFAULT;

[PATCH 28/28] fuse: disable direct reclaim for any fuse server that uses iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Any fuse server that uses iomap can create a substantial amount of dirty
pages in the pagecache because we don't write dirty stuff until reclaim
or fsync.  Therefore, memory reclaim on any fuse iomap server musn't
ever recurse back into the same filesystem.  We must also never throttle
the fuse server writes to a bdi because that will just slow down
metadata operations.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/file_iomap.c |    6 ++++++
 1 file changed, 6 insertions(+)


diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 30db4079ab8a55..524c26e53674f2 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1014,6 +1014,12 @@ static void fuse_iomap_config_reply(struct fuse_mount *fm,
 	fc->iomap_conn.no_end = 0;
 	fc->iomap_conn.no_ioend = 0;
 
+	/*
+	 * We could be on the hook for a substantial amount of writeback, so
+	 * prohibit reclaim from recursing into fuse or the kernel from
+	 * throttling any bdis that the fuse server might write to.
+	 */
+	current->flags |= PF_MEMALLOC_NOFS | PF_LOCAL_THROTTLE;
 done:
 	kfree(ia);
 	fuse_finish_init(fc, ok);

[PATCH 1/3] fuse: make the root nodeid dynamic

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Change this from a hardcoded constant to a dynamic field so that fuse
servers don't need to translate.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h  |    7 +++++--
 fs/fuse/dir.c     |   10 ++++++----
 fs/fuse/inode.c   |   11 +++++++----
 fs/fuse/readdir.c |   10 +++++-----
 4 files changed, 23 insertions(+), 15 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 777826115d3e80..70942340e33855 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -684,6 +684,9 @@ struct fuse_conn {
 
 	struct rcu_head rcu;
 
+	/* node id of the root directory */
+	u64 root_nodeid;
+
 	/** The user id for this mount */
 	kuid_t user_id;
 
@@ -1127,9 +1130,9 @@ static inline u64 get_node_id(struct inode *inode)
 	return get_fuse_inode(inode)->nodeid;
 }
 
-static inline int invalid_nodeid(u64 nodeid)
+static inline int invalid_nodeid(const struct fuse_conn *fc, u64 nodeid)
 {
-	return !nodeid || nodeid == FUSE_ROOT_ID;
+	return !nodeid || nodeid == fc->root_nodeid;
 }
 
 static inline u64 fuse_get_attr_version(struct fuse_conn *fc)
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index b5e3536f1d53c1..c6e83b724f8cd0 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -386,7 +386,7 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name
 	err = -EIO;
 	if (fuse_invalid_attr(&outarg->attr))
 		goto out_put_forget;
-	if (outarg->nodeid == FUSE_ROOT_ID && outarg->generation != 0) {
+	if (outarg->nodeid == fm->fc->root_nodeid && outarg->generation != 0) {
 		pr_warn_once("root generation should be zero\n");
 		outarg->generation = 0;
 	}
@@ -436,7 +436,7 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
 		goto out_err;
 
 	err = -EIO;
-	if (inode && get_node_id(inode) == FUSE_ROOT_ID)
+	if (inode && get_node_id(inode) == fc->root_nodeid)
 		goto out_iput;
 
 	newent = d_splice_alias(inode, entry);
@@ -687,7 +687,8 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
 		goto out_free_ff;
 
 	err = -EIO;
-	if (!S_ISREG(outentry.attr.mode) || invalid_nodeid(outentry.nodeid) ||
+	if (!S_ISREG(outentry.attr.mode) ||
+	    invalid_nodeid(fm->fc, outentry.nodeid) ||
 	    fuse_invalid_attr(&outentry.attr))
 		goto out_free_ff;
 
@@ -838,7 +839,8 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
 		goto out_put_forget_req;
 
 	err = -EIO;
-	if (invalid_nodeid(outarg.nodeid) || fuse_invalid_attr(&outarg.attr))
+	if (invalid_nodeid(fm->fc, outarg.nodeid) ||
+	    fuse_invalid_attr(&outarg.attr))
 		goto out_put_forget_req;
 
 	if ((outarg.attr.mode ^ mode) & S_IFMT)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index beb9ee62b6b861..350805fa61690c 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -997,6 +997,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
 	fc->max_pages_limit = fuse_max_pages_limit;
 	fc->name_max = FUSE_NAME_LOW_MAX;
 	fc->timeout.req_timeout = 0;
+	fc->root_nodeid = FUSE_ROOT_ID;
 
 	if (IS_ENABLED(CONFIG_FUSE_BACKING))
 		fuse_backing_files_init(fc);
@@ -1052,12 +1053,14 @@ EXPORT_SYMBOL_GPL(fuse_conn_get);
 static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned int mode)
 {
 	struct fuse_attr attr;
+	struct fuse_conn *fc = get_fuse_conn_super(sb);
+
 	memset(&attr, 0, sizeof(attr));
 
 	attr.mode = mode;
-	attr.ino = FUSE_ROOT_ID;
+	attr.ino = fc->root_nodeid;
 	attr.nlink = 1;
-	return fuse_iget(sb, FUSE_ROOT_ID, 0, &attr, 0, 0, 0);
+	return fuse_iget(sb, fc->root_nodeid, 0, &attr, 0, 0, 0);
 }
 
 struct fuse_inode_handle {
@@ -1101,7 +1104,7 @@ static struct dentry *fuse_get_dentry(struct super_block *sb,
 		goto out_iput;
 
 	entry = d_obtain_alias(inode);
-	if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
+	if (!IS_ERR(entry) && get_node_id(inode) != fc->root_nodeid)
 		fuse_invalidate_entry_cache(entry);
 
 	return entry;
@@ -1194,7 +1197,7 @@ static struct dentry *fuse_get_parent(struct dentry *child)
 	}
 
 	parent = d_obtain_alias(inode);
-	if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
+	if (!IS_ERR(parent) && get_node_id(inode) != fc->root_nodeid)
 		fuse_invalidate_entry_cache(parent);
 
 	return parent;
diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
index c2aae2eef0868b..45dd932eb03a5e 100644
--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -185,12 +185,12 @@ static int fuse_direntplus_link(struct file *file,
 			return 0;
 	}
 
-	if (invalid_nodeid(o->nodeid))
-		return -EIO;
-	if (fuse_invalid_attr(&o->attr))
-		return -EIO;
-
 	fc = get_fuse_conn(dir);
+	if (invalid_nodeid(fc, o->nodeid))
+		return -EIO;
+	if (fuse_invalid_attr(&o->attr))
+		return -EIO;
+
 	epoch = atomic_read(&fc->epoch);
 
 	name.hash = full_name_hash(parent, name.name, name.len);

[PATCH 2/3] fuse_trace: make the root nodeid dynamic

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Enhance the iomap config tracepoint to report the node id of the root
directory.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 1befea65d4b15c..9c2eb497730b06 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -988,6 +988,7 @@ TRACE_EVENT(fuse_iomap_config,
 
 	TP_STRUCT__entry(
 		__field(dev_t,			connection)
+		__field(uint64_t,		root_nodeid)
 
 		__field(uint32_t,		flags)
 		__field(uint32_t,		blocksize)
@@ -1002,6 +1003,7 @@ TRACE_EVENT(fuse_iomap_config,
 
 	TP_fast_assign(
 		__entry->connection	=	fm->fc->dev;
+		__entry->root_nodeid	=	fm->fc->root_nodeid;
 		__entry->flags		=	outarg->flags;
 		__entry->blocksize	=	outarg->s_blocksize;
 		__entry->max_links	=	outarg->s_max_links;
@@ -1012,8 +1014,8 @@ TRACE_EVENT(fuse_iomap_config,
 		__entry->uuid_len	=	outarg->s_uuid_len;
 	),
 
-	TP_printk("connection %u flags (%s) blocksize 0x%x max_links %u time_gran %u time_min %lld time_max %lld maxbytes 0x%llx uuid_len %u",
-		  __entry->connection,
+	TP_printk("connection %u root_ino 0x%llx flags (%s) blocksize 0x%x max_links %u time_gran %u time_min %lld time_max %lld maxbytes 0x%llx uuid_len %u",
+		  __entry->connection, __entry->root_nodeid,
 		  __print_flags(__entry->flags, "|", FUSE_IOMAP_CONFIG_STRINGS),
 		  __entry->blocksize, __entry->max_links, __entry->time_gran,
 		  __entry->time_min, __entry->time_max, __entry->maxbytes,

[PATCH 3/3] fuse: allow setting of root nodeid

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Provide a new mount option so that fuse servers can actually set the
root nodeid.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h |    2 ++
 fs/fuse/inode.c  |   11 +++++++++++
 2 files changed, 13 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 70942340e33855..fb60686fb9c61a 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -619,6 +619,7 @@ struct fuse_fs_context {
 	int fd;
 	struct file *file;
 	unsigned int rootmode;
+	u64 root_nodeid;
 	kuid_t user_id;
 	kgid_t group_id;
 	bool is_bdev:1;
@@ -633,6 +634,7 @@ struct fuse_fs_context {
 	bool no_force_umount:1;
 	bool legacy_opts_show:1;
 	bool local_fs:1;
+	bool root_nodeid_present:1;
 	enum fuse_dax_mode dax_mode;
 	unsigned int max_read;
 	unsigned int blksize;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 350805fa61690c..e74d39ac05a570 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -781,6 +781,7 @@ enum {
 	OPT_ALLOW_OTHER,
 	OPT_MAX_READ,
 	OPT_BLKSIZE,
+	OPT_ROOT_NODEID,
 	OPT_ERR
 };
 
@@ -795,6 +796,7 @@ static const struct fs_parameter_spec fuse_fs_parameters[] = {
 	fsparam_u32	("max_read",		OPT_MAX_READ),
 	fsparam_u32	("blksize",		OPT_BLKSIZE),
 	fsparam_string	("subtype",		OPT_SUBTYPE),
+	fsparam_u64	("root_nodeid",		OPT_ROOT_NODEID),
 	{}
 };
 
@@ -890,6 +892,11 @@ static int fuse_parse_param(struct fs_context *fsc, struct fs_parameter *param)
 		ctx->blksize = result.uint_32;
 		break;
 
+	case OPT_ROOT_NODEID:
+		ctx->root_nodeid = result.uint_64;
+		ctx->root_nodeid_present = true;
+		break;
+
 	default:
 		return -EINVAL;
 	}
@@ -925,6 +932,8 @@ static int fuse_show_options(struct seq_file *m, struct dentry *root)
 			seq_printf(m, ",max_read=%u", fc->max_read);
 		if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
 			seq_printf(m, ",blksize=%lu", sb->s_blocksize);
+		if (fc->root_nodeid && fc->root_nodeid != FUSE_ROOT_ID)
+			seq_printf(m, ",root_nodeid=%llu", fc->root_nodeid);
 	}
 #ifdef CONFIG_FUSE_DAX
 	if (fc->dax_mode == FUSE_DAX_ALWAYS)
@@ -1910,6 +1919,8 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 	sb->s_flags |= SB_POSIXACL;
 
 	fc->default_permissions = ctx->default_permissions;
+	if (ctx->root_nodeid_present)
+		fc->root_nodeid = ctx->root_nodeid;
 	fc->allow_other = ctx->allow_other;
 	fc->user_id = ctx->user_id;
 	fc->group_id = ctx->group_id;

[PATCH 1/9] fuse: enable caching of timestamps

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Cache the timestamps in the kernel so that the kernel sends FUSE_SETATTR
calls to the fuse server after writes, because the iomap infrastructure
won't do that for us.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/dir.c        |    5 ++++-
 fs/fuse/file.c       |   18 ++++++++++++------
 fs/fuse/file_iomap.c |    6 ++++++
 fs/fuse/inode.c      |   13 +++++++------
 4 files changed, 29 insertions(+), 13 deletions(-)


diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index c6e83b724f8cd0..380559950c3444 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -2062,7 +2062,8 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	struct fuse_attr_out outarg;
 	const bool is_iomap = fuse_inode_has_iomap(inode);
 	bool is_truncate = false;
-	bool is_wb = fc->writeback_cache && S_ISREG(inode->i_mode);
+	bool is_wb = (is_iomap || fc->writeback_cache) &&
+		     S_ISREG(inode->i_mode);
 	loff_t oldsize;
 	int err;
 	bool trust_local_cmtime = is_wb;
@@ -2196,6 +2197,8 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	spin_lock(&fi->lock);
 	/* the kernel maintains i_mtime locally */
 	if (trust_local_cmtime) {
+		if ((attr->ia_valid & ATTR_ATIME) && is_iomap)
+			inode_set_atime_to_ts(inode, attr->ia_atime);
 		if (attr->ia_valid & ATTR_MTIME)
 			inode_set_mtime_to_ts(inode, attr->ia_mtime);
 		if (attr->ia_valid & ATTR_CTIME)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 9476f14035bb7f..0ed13082d0d00d 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -240,7 +240,7 @@ static int fuse_open(struct inode *inode, struct file *file)
 	int err;
 	const bool is_iomap = fuse_inode_has_iomap(inode);
 	bool is_truncate = (file->f_flags & O_TRUNC) && fc->atomic_o_trunc;
-	bool is_wb_truncate = is_truncate && fc->writeback_cache;
+	bool is_wb_truncate = is_truncate && (is_iomap || fc->writeback_cache);
 	bool dax_truncate = is_truncate && FUSE_IS_DAX(inode);
 
 	if (fuse_is_bad(inode))
@@ -453,12 +453,14 @@ static int fuse_flush(struct file *file, fl_owner_t id)
 	struct fuse_file *ff = file->private_data;
 	struct fuse_flush_in inarg;
 	FUSE_ARGS(args);
+	const bool is_iomap = fuse_inode_has_iomap(inode);
 	int err;
 
 	if (fuse_is_bad(inode))
 		return -EIO;
 
-	if (ff->open_flags & FOPEN_NOFLUSH && !fm->fc->writeback_cache)
+	if ((ff->open_flags & FOPEN_NOFLUSH) &&
+	    !fm->fc->writeback_cache && !is_iomap)
 		return 0;
 
 	err = write_inode_now(inode, 1);
@@ -494,7 +496,7 @@ static int fuse_flush(struct file *file, fl_owner_t id)
 	 * In memory i_blocks is not maintained by fuse, if writeback cache is
 	 * enabled, i_blocks from cached attr may not be accurate.
 	 */
-	if (!err && fm->fc->writeback_cache)
+	if (!err && (is_iomap || fm->fc->writeback_cache))
 		fuse_invalidate_attr_mask(inode, STATX_BLOCKS);
 	return err;
 }
@@ -796,8 +798,10 @@ static void fuse_short_read(struct inode *inode, u64 attr_ver, size_t num_read,
 	 * If writeback_cache is enabled, a short read means there's a hole in
 	 * the file.  Some data after the hole is in page cache, but has not
 	 * reached the client fs yet.  So the hole is not present there.
+	 * If iomap is enabled, a short read means we hit EOF so there's
+	 * nothing to adjust.
 	 */
-	if (!fc->writeback_cache) {
+	if (!fc->writeback_cache && !fuse_inode_has_iomap(inode)) {
 		loff_t pos = folio_pos(ap->folios[0]) + num_read;
 		fuse_read_update_size(inode, pos, attr_ver);
 	}
@@ -1412,6 +1416,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 			    unsigned int flags, struct iomap *iomap,
 			    struct iomap *srcmap)
 {
+	WARN_ON(fuse_inode_has_iomap(inode));
+
 	iomap->type = IOMAP_MAPPED;
 	iomap->length = length;
 	iomap->offset = offset;
@@ -1979,7 +1985,7 @@ static void fuse_writepage_end(struct fuse_mount *fm, struct fuse_args *args,
 	 * Do this only if writeback_cache is not enabled.  If writeback_cache
 	 * is enabled, we trust local ctime/mtime.
 	 */
-	if (!fc->writeback_cache)
+	if (!fc->writeback_cache && !fuse_inode_has_iomap(inode))
 		fuse_invalidate_attr_mask(inode, FUSE_STATX_MODIFY);
 	spin_lock(&fi->lock);
 	fi->writectr--;
@@ -3065,7 +3071,7 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	/* mark unstable when write-back is not used, and file_out gets
 	 * extended */
 	const bool is_iomap = fuse_inode_has_iomap(inode_out);
-	bool is_unstable = (!fc->writeback_cache) &&
+	bool is_unstable = (!fc->writeback_cache && !is_iomap) &&
 			   ((pos_out + len) > inode_out->i_size);
 
 	if (fc->no_copy_file_range)
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 524c26e53674f2..1fc9a9b7b75094 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1769,6 +1769,12 @@ static inline void fuse_inode_set_iomap(struct inode *inode)
 
 	ASSERT(fuse_has_iomap(inode));
 
+	/*
+	 * Manage timestamps ourselves, don't make the fuse server do it.  This
+	 * is critical for mtime updates to work correctly with page_mkwrite.
+	 */
+	inode->i_flags &= ~S_NOCMTIME;
+	inode->i_flags &= ~S_NOATIME;
 	inode->i_data.a_ops = &fuse_iomap_aops;
 
 	INIT_WORK(&fi->ioend_work, fuse_iomap_end_io);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index e74d39ac05a570..b63e4e1d8f45ce 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -328,10 +328,11 @@ u32 fuse_get_cache_mask(struct inode *inode)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 
-	if (!fc->writeback_cache || !S_ISREG(inode->i_mode))
-		return 0;
+	if (S_ISREG(inode->i_mode) &&
+	    (fuse_inode_has_iomap(inode) || fc->writeback_cache))
+		return STATX_MTIME | STATX_CTIME | STATX_SIZE;
 
-	return STATX_MTIME | STATX_CTIME | STATX_SIZE;
+	return 0;
 }
 
 static void fuse_change_attributes_i(struct inode *inode, struct fuse_attr *attr,
@@ -346,9 +347,9 @@ static void fuse_change_attributes_i(struct inode *inode, struct fuse_attr *attr
 
 	spin_lock(&fi->lock);
 	/*
-	 * In case of writeback_cache enabled, writes update mtime, ctime and
-	 * may update i_size.  In these cases trust the cached value in the
-	 * inode.
+	 * In case of writeback_cache or iomap enabled, writes update mtime,
+	 * ctime and may update i_size.  In these cases trust the cached value
+	 * in the inode.
 	 */
 	cache_mask = fuse_get_cache_mask(inode);
 	if (cache_mask & STATX_SIZE)

[PATCH 2/9] fuse: force a ctime update after a fileattr_set call when in iomap mode

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

In iomap mode, the kernel is in charge of driving ctime updates to
the fuse server and ignores updates coming from the fuse server.
Therefore, when someone calls fileattr_set to change file attributes, we
must force a ctime update.

Found by generic/277.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/ioctl.c |   11 +++++++++++
 1 file changed, 11 insertions(+)


diff --git a/fs/fuse/ioctl.c b/fs/fuse/ioctl.c
index 57032eadca6c27..f5f7d806262cdf 100644
--- a/fs/fuse/ioctl.c
+++ b/fs/fuse/ioctl.c
@@ -548,8 +548,13 @@ int fuse_fileattr_set(struct mnt_idmap *idmap,
 	struct fuse_file *ff;
 	unsigned int flags = fa->flags;
 	struct fsxattr xfa;
+	struct file_kattr old_ma = { };
+	bool is_wb = (fuse_get_cache_mask(inode) & STATX_CTIME);
 	int err;
 
+	if (is_wb)
+		vfs_fileattr_get(dentry, &old_ma);
+
 	ff = fuse_priv_ioctl_prepare(inode);
 	if (IS_ERR(ff))
 		return PTR_ERR(ff);
@@ -573,6 +578,12 @@ int fuse_fileattr_set(struct mnt_idmap *idmap,
 
 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);
+	/*
+	 * If we cache ctime updates and the fileattr changed, then force a
+	 * ctime update.
+	 */
+	if (is_wb && memcmp(&old_ma, fa, sizeof(old_ma)))
+		fuse_update_ctime(inode);
 
 	if (err == -ENOTTY)
 		err = -EOPNOTSUPP;

[PATCH 3/9] fuse: allow local filesystems to set some VFS iflags

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

There are three inode flags (immutable, append, sync) that are enforced
by the VFS.  Whenever we go around setting iflags, let's update the VFS
state so that they actually work.  Make it so that the fuse server can
set these three inode flags at load time and have the kernel advertise
and enforce them.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |    1 +
 include/uapi/linux/fuse.h |    8 +++++++
 fs/fuse/dir.c             |    1 +
 fs/fuse/inode.c           |    1 +
 fs/fuse/ioctl.c           |   53 +++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 64 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index fb60686fb9c61a..ae03a898d3aa7d 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1629,6 +1629,7 @@ long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
 int fuse_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
 int fuse_fileattr_set(struct mnt_idmap *idmap,
 		      struct dentry *dentry, struct file_kattr *fa);
+void fuse_fileattr_init(struct inode *inode, const struct fuse_attr *attr);
 
 /* iomode.c */
 int fuse_file_cached_io_open(struct inode *inode, struct fuse_file *ff);
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 472605d7ff6a2f..94ec220beb5f79 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -242,6 +242,8 @@
  *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
  *  - add FUSE_NOTIFY_IOMAP_DEV_INVAL to invalidate iomap bdev ranges
  *  - add FUSE_ATTR_ATOMIC for single-fsblock atomic write support
+ *  - add FUSE_ATTR_{SYNC,IMMUTABLE,APPEND} for VFS enforcement of file
+ *    attributes
  */
 
 #ifndef _LINUX_FUSE_H
@@ -597,11 +599,17 @@ struct fuse_file_lock {
  * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
  * FUSE_ATTR_IOMAP: Use iomap for this inode
  * FUSE_ATTR_ATOMIC: Enable untorn writes
+ * FUSE_ATTR_SYNC: File writes are synchronous
+ * FUSE_ATTR_IMMUTABLE: File is immutable
+ * FUSE_ATTR_APPEND: File is append-only
  */
 #define FUSE_ATTR_SUBMOUNT      (1 << 0)
 #define FUSE_ATTR_DAX		(1 << 1)
 #define FUSE_ATTR_IOMAP		(1 << 2)
 #define FUSE_ATTR_ATOMIC	(1 << 3)
+#define FUSE_ATTR_SYNC		(1 << 4)
+#define FUSE_ATTR_IMMUTABLE	(1 << 5)
+#define FUSE_ATTR_APPEND	(1 << 6)
 
 /**
  * Open flags
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 380559950c3444..30c914ba4bb23f 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1254,6 +1254,7 @@ static void fuse_fillattr(struct mnt_idmap *idmap, struct inode *inode,
 		blkbits = fc->blkbits;
 
 	stat->blksize = 1 << blkbits;
+	generic_fill_statx_attr(inode, stat);
 }
 
 static void fuse_statx_to_attr(struct fuse_statx *sx, struct fuse_attr *attr)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index b63e4e1d8f45ce..f845864bf50dee 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -521,6 +521,7 @@ struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 			inode->i_flags |= S_NOCMTIME;
 		inode->i_generation = generation;
 		fuse_init_inode(inode, attr, fc);
+		fuse_fileattr_init(inode, attr);
 		unlock_new_inode(inode);
 	} else if (fuse_stale_inode(inode, generation, attr)) {
 		/* nodeid was reused, any I/O on the old inode should fail */
diff --git a/fs/fuse/ioctl.c b/fs/fuse/ioctl.c
index f5f7d806262cdf..fc0c9bac7a5939 100644
--- a/fs/fuse/ioctl.c
+++ b/fs/fuse/ioctl.c
@@ -502,6 +502,56 @@ static void fuse_priv_ioctl_cleanup(struct inode *inode, struct fuse_file *ff)
 	fuse_file_release(inode, ff, O_RDONLY, NULL, S_ISDIR(inode->i_mode));
 }
 
+static inline void update_iflag(struct inode *inode, unsigned int iflag,
+				bool set)
+{
+	if (set)
+		inode->i_flags |= iflag;
+	else
+		inode->i_flags &= ~iflag;
+}
+
+static void fuse_fileattr_update_inode(struct inode *inode,
+				       const struct file_kattr *fa)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	unsigned int old_iflags = inode->i_flags;
+
+	if (!fc->local_fs)
+		return;
+
+	if (fa->flags_valid) {
+		update_iflag(inode, S_SYNC, fa->flags & FS_SYNC_FL);
+		update_iflag(inode, S_IMMUTABLE, fa->flags & FS_IMMUTABLE_FL);
+		update_iflag(inode, S_APPEND, fa->flags & FS_APPEND_FL);
+	} else if (fa->fsx_valid) {
+		update_iflag(inode, S_SYNC, fa->fsx_xflags & FS_XFLAG_SYNC);
+		update_iflag(inode, S_IMMUTABLE,
+					fa->fsx_xflags & FS_XFLAG_IMMUTABLE);
+		update_iflag(inode, S_APPEND, fa->fsx_xflags & FS_XFLAG_APPEND);
+	}
+
+	if (old_iflags != inode->i_flags)
+		fuse_invalidate_attr(inode);
+}
+
+void fuse_fileattr_init(struct inode *inode, const struct fuse_attr *attr)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	if (!fc->local_fs)
+		return;
+
+	if (attr->flags & FUSE_ATTR_SYNC)
+		inode->i_flags |= S_SYNC;
+
+	if (attr->flags & FUSE_ATTR_IMMUTABLE)
+		inode->i_flags |= S_IMMUTABLE;
+
+	if (attr->flags & FUSE_ATTR_APPEND)
+		inode->i_flags |= S_APPEND;
+}
+
 int fuse_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
 {
 	struct inode *inode = d_inode(dentry);
@@ -574,7 +624,10 @@ int fuse_fileattr_set(struct mnt_idmap *idmap,
 
 		err = fuse_priv_ioctl(inode, ff, FS_IOC_FSSETXATTR,
 				      &xfa, sizeof(xfa));
+		if (err)
+			goto cleanup;
 	}
+	fuse_fileattr_update_inode(inode, fa);
 
 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);

[PATCH 4/9] fuse_trace: allow local filesystems to set some VFS iflags

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   29 +++++++++++++++++++++++++++++
 fs/fuse/ioctl.c      |    6 ++++++
 2 files changed, 35 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 9c2eb497730b06..2aff78a30503ee 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -176,6 +176,35 @@ TRACE_EVENT(fuse_request_end,
 		  __entry->unique, __entry->len, __entry->error)
 );
 
+DECLARE_EVENT_CLASS(fuse_fileattr_class,
+	TP_PROTO(const struct inode *inode, unsigned int old_iflags),
+
+	TP_ARGS(inode, old_iflags),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		__field(unsigned int,		old_iflags)
+		__field(unsigned int,		new_iflags)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->old_iflags	=	old_iflags;
+		__entry->new_iflags	=	inode->i_flags;
+	),
+
+	TP_printk(FUSE_INODE_FMT " old_iflags 0x%x iflags 0x%x",
+		  FUSE_INODE_PRINTK_ARGS,
+		  __entry->old_iflags,
+		  __entry->new_iflags)
+);
+#define DEFINE_FUSE_FILEATTR_EVENT(name)	\
+DEFINE_EVENT(fuse_fileattr_class, name,		\
+	TP_PROTO(const struct inode *inode, unsigned int old_iflags), \
+	TP_ARGS(inode, old_iflags))
+DEFINE_FUSE_FILEATTR_EVENT(fuse_fileattr_update_inode);
+DEFINE_FUSE_FILEATTR_EVENT(fuse_fileattr_init);
+
 #ifdef CONFIG_FUSE_BACKING
 #define FUSE_BACKING_FLAG_STRINGS \
 	{ FUSE_BACKING_TYPE_PASSTHROUGH,	"pass" }, \
diff --git a/fs/fuse/ioctl.c b/fs/fuse/ioctl.c
index fc0c9bac7a5939..2ac1911dc5cc83 100644
--- a/fs/fuse/ioctl.c
+++ b/fs/fuse/ioctl.c
@@ -4,6 +4,7 @@
  */
 
 #include "fuse_i.h"
+#include "fuse_trace.h"
 
 #include <linux/uio.h>
 #include <linux/compat.h>
@@ -531,6 +532,8 @@ static void fuse_fileattr_update_inode(struct inode *inode,
 		update_iflag(inode, S_APPEND, fa->fsx_xflags & FS_XFLAG_APPEND);
 	}
 
+	trace_fuse_fileattr_update_inode(inode, old_iflags);
+
 	if (old_iflags != inode->i_flags)
 		fuse_invalidate_attr(inode);
 }
@@ -538,6 +541,7 @@ static void fuse_fileattr_update_inode(struct inode *inode,
 void fuse_fileattr_init(struct inode *inode, const struct fuse_attr *attr)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
+	unsigned int old_iflags = inode->i_flags;
 
 	if (!fc->local_fs)
 		return;
@@ -550,6 +554,8 @@ void fuse_fileattr_init(struct inode *inode, const struct fuse_attr *attr)
 
 	if (attr->flags & FUSE_ATTR_APPEND)
 		inode->i_flags |= S_APPEND;
+
+	trace_fuse_fileattr_init(inode, old_iflags);
 }
 
 int fuse_fileattr_get(struct dentry *dentry, struct file_kattr *fa)

[PATCH 5/9] fuse: cache atime when in iomap mode

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

When we're running in iomap mode, allow the kernel to cache the access
timestamp to further reduce the number of roundtrips to the fuse server.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/dir.c   |    5 +++++
 fs/fuse/inode.c |   19 ++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)


diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 30c914ba4bb23f..8247e5196fd0b2 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -2033,6 +2033,11 @@ int fuse_flush_times(struct inode *inode, struct fuse_file *ff)
 		inarg.ctime = inode_get_ctime_sec(inode);
 		inarg.ctimensec = inode_get_ctime_nsec(inode);
 	}
+	if (fuse_inode_has_iomap(inode)) {
+		inarg.valid |= FATTR_ATIME;
+		inarg.atime = inode_get_atime_sec(inode);
+		inarg.atimensec = inode_get_atime_nsec(inode);
+	}
 	if (ff) {
 		inarg.valid |= FATTR_FH;
 		inarg.fh = ff->fh;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index f845864bf50dee..c29a8cbc55fa27 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -266,7 +266,8 @@ void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 	attr->mtimensec = min_t(u32, attr->mtimensec, NSEC_PER_SEC - 1);
 	attr->ctimensec = min_t(u32, attr->ctimensec, NSEC_PER_SEC - 1);
 
-	inode_set_atime(inode, attr->atime, attr->atimensec);
+	if (!(cache_mask & STATX_ATIME))
+		inode_set_atime(inode, attr->atime, attr->atimensec);
 	/* mtime from server may be stale due to local buffered write */
 	if (!(cache_mask & STATX_MTIME)) {
 		inode_set_mtime(inode, attr->mtime, attr->mtimensec);
@@ -328,8 +329,12 @@ u32 fuse_get_cache_mask(struct inode *inode)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 
-	if (S_ISREG(inode->i_mode) &&
-	    (fuse_inode_has_iomap(inode) || fc->writeback_cache))
+	if (!S_ISREG(inode->i_mode))
+		return 0;
+
+	if (fuse_inode_has_iomap(inode))
+		return STATX_MTIME | STATX_CTIME | STATX_ATIME | STATX_SIZE;
+	if (fc->writeback_cache)
 		return STATX_MTIME | STATX_CTIME | STATX_SIZE;
 
 	return 0;
@@ -448,6 +453,14 @@ static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr,
 				   new_decode_dev(attr->rdev));
 	} else
 		BUG();
+
+	/*
+	 * iomap caches atime too, so we must load it from the fuse server
+	 * at instantiation time.
+	 */
+	if (fuse_inode_has_iomap(inode))
+		inode_set_atime(inode, attr->atime, attr->atimensec);
+
 	/*
 	 * Ensure that we don't cache acls for daemons without FUSE_POSIX_ACL
 	 * so they see the exact same behavior as before.

[PATCH 6/9] fuse: let the kernel handle KILL_SUID/KILL_SGID for iomap filesystems

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Let the kernel handle killing the suid/sgid bits because the
write/falloc/truncate/chown code already does this, and we don't have to
worry about external modifications that are only visible to the fuse
server (i.e. we're not a cluster fs).

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/dir.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)


diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 8247e5196fd0b2..2e1837b2363e83 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -2268,6 +2268,7 @@ static int fuse_setattr(struct mnt_idmap *idmap, struct dentry *entry,
 	struct inode *inode = d_inode(entry);
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct file *file = (attr->ia_valid & ATTR_FILE) ? attr->ia_file : NULL;
+	const bool is_iomap = fuse_inode_has_iomap(inode);
 	int ret;
 
 	if (fuse_is_bad(inode))
@@ -2276,15 +2277,19 @@ static int fuse_setattr(struct mnt_idmap *idmap, struct dentry *entry,
 	if (!fuse_allow_current_process(get_fuse_conn(inode)))
 		return -EACCES;
 
-	if (attr->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID)) {
+	if (!is_iomap &&
+	    (attr->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))) {
 		attr->ia_valid &= ~(ATTR_KILL_SUID | ATTR_KILL_SGID |
 				    ATTR_MODE);
 
 		/*
 		 * The only sane way to reliably kill suid/sgid is to do it in
-		 * the userspace filesystem
+		 * the userspace filesystem if this isn't an iomap file.  For
+		 * iomap filesystems we let the kernel kill the setuid/setgid
+		 * bits.
 		 *
-		 * This should be done on write(), truncate() and chown().
+		 * This should be done on write(), truncate(), chown(), and
+		 * fallocate().
 		 */
 		if (!fc->handle_killpriv && !fc->handle_killpriv_v2) {
 			/*

[PATCH 7/9] fuse_trace: let the kernel handle KILL_SUID/KILL_SGID for iomap filesystems

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   58 ++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/dir.c        |    5 ++++
 2 files changed, 63 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 2aff78a30503ee..1f900580b14937 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -205,6 +205,64 @@ DEFINE_EVENT(fuse_fileattr_class, name,		\
 DEFINE_FUSE_FILEATTR_EVENT(fuse_fileattr_update_inode);
 DEFINE_FUSE_FILEATTR_EVENT(fuse_fileattr_init);
 
+TRACE_EVENT(fuse_setattr_fill,
+	TP_PROTO(const struct inode *inode,
+		 const struct fuse_setattr_in *inarg),
+	TP_ARGS(inode, inarg),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		__field(umode_t,		mode)
+		__field(uint32_t,		valid)
+		__field(umode_t,		new_mode)
+		__field(uint64_t,		new_size)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->mode		=	inode->i_mode;
+		__entry->valid		=	inarg->valid;
+		__entry->new_mode	=	inarg->mode;
+		__entry->new_size	=	inarg->size;
+	),
+
+	TP_printk(FUSE_INODE_FMT " mode 0%o valid 0x%x new_mode 0%o new_size 0x%llx",
+		  FUSE_INODE_PRINTK_ARGS,
+		  __entry->mode,
+		  __entry->valid,
+		  __entry->new_mode,
+		  __entry->new_size)
+);
+
+TRACE_EVENT(fuse_setattr,
+	TP_PROTO(const struct inode *inode,
+		 const struct iattr *inarg),
+	TP_ARGS(inode, inarg),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		__field(umode_t,		mode)
+		__field(uint32_t,		valid)
+		__field(umode_t,		new_mode)
+		__field(uint64_t,		new_size)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->mode		=	inode->i_mode;
+		__entry->valid		=	inarg->ia_valid;
+		__entry->new_mode	=	inarg->ia_mode;
+		__entry->new_size	=	inarg->ia_size;
+	),
+
+	TP_printk(FUSE_INODE_FMT " mode 0%o valid 0x%x new_mode 0%o new_size 0x%llx",
+		  FUSE_INODE_PRINTK_ARGS,
+		  __entry->mode,
+		  __entry->valid,
+		  __entry->new_mode,
+		  __entry->new_size)
+);
+
 #ifdef CONFIG_FUSE_BACKING
 #define FUSE_BACKING_FLAG_STRINGS \
 	{ FUSE_BACKING_TYPE_PASSTHROUGH,	"pass" }, \
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 2e1837b2363e83..58106f49395697 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -7,6 +7,7 @@
 */
 
 #include "fuse_i.h"
+#include "fuse_trace.h"
 
 #include <linux/pagemap.h>
 #include <linux/file.h>
@@ -2002,6 +2003,8 @@ static void fuse_setattr_fill(struct fuse_conn *fc, struct fuse_args *args,
 			      struct fuse_setattr_in *inarg_p,
 			      struct fuse_attr_out *outarg_p)
 {
+	trace_fuse_setattr_fill(inode, inarg_p);
+
 	args->opcode = FUSE_SETATTR;
 	args->nodeid = get_node_id(inode);
 	args->in_numargs = 1;
@@ -2277,6 +2280,8 @@ static int fuse_setattr(struct mnt_idmap *idmap, struct dentry *entry,
 	if (!fuse_allow_current_process(get_fuse_conn(inode)))
 		return -EACCES;
 
+	trace_fuse_setattr(inode, attr);
+
 	if (!is_iomap &&
 	    (attr->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))) {
 		attr->ia_valid &= ~(ATTR_KILL_SUID | ATTR_KILL_SGID |

[PATCH 8/9] fuse: update ctime when updating acls on an iomap inode

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

In iomap mode, the fuse kernel driver is in charge of updating file
attributes, so we need to update ctime after an ACL change.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/acl.c |   17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 4faee72f1365a5..9b24c53b510405 100644
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -109,6 +109,7 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	const char *name;
 	umode_t mode = inode->i_mode;
+	const bool is_iomap = fuse_inode_has_iomap(inode);
 	int ret;
 
 	if (fuse_is_bad(inode))
@@ -179,10 +180,24 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 			ret = 0;
 	}
 
-	/* If we scheduled a mode update above, push that to userspace now. */
 	if (!ret) {
 		struct iattr attr = { };
 
+		/*
+		 * When we're running in iomap mode, we need to update mode and
+		 * ctime ourselves instead of letting the fuse server figure
+		 * that out.
+		 */
+		if (is_iomap) {
+			attr.ia_valid |= ATTR_CTIME;
+			inode_set_ctime_current(inode);
+			attr.ia_ctime = inode_get_ctime(inode);
+		}
+
+		/*
+		 * If we scheduled a mode update above, push that to userspace
+		 * now.
+		 */
 		if (mode != inode->i_mode) {
 			attr.ia_valid |= ATTR_MODE;
 			attr.ia_mode = mode;

[PATCH 9/9] fuse: always cache ACLs when using iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Keep ACLs cached in memory when we're using iomap, so that we don't have
to make a round trip to the fuse server.  This might want to become a
FUSE_ATTR_ flag.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/acl.c     |   12 +++++++++---
 fs/fuse/dir.c     |   11 ++++++++---
 fs/fuse/readdir.c |    3 ++-
 3 files changed, 19 insertions(+), 7 deletions(-)


diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 9b24c53b510405..a9f152ddc1faec 100644
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -210,10 +210,16 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 	if (fc->posix_acl) {
 		/*
 		 * Fuse daemons without FUSE_POSIX_ACL never cached POSIX ACLs
-		 * and didn't invalidate attributes. Retain that behavior.
+		 * and didn't invalidate attributes. Retain that behavior
+		 * except for iomap, where we assume that only the source of
+		 * ACL changes is userspace.
 		 */
-		forget_all_cached_acls(inode);
-		fuse_invalidate_attr(inode);
+		if (!ret && is_iomap) {
+			set_cached_acl(inode, type, acl);
+		} else {
+			forget_all_cached_acls(inode);
+			fuse_invalidate_attr(inode);
+		}
 	}
 
 	return ret;
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 58106f49395697..9adaf262bda975 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -261,7 +261,8 @@ static int fuse_dentry_revalidate(struct inode *dir, const struct qstr *name,
 		    fuse_stale_inode(inode, outarg.generation, &outarg.attr))
 			goto invalid;
 
-		forget_all_cached_acls(inode);
+		if (!fuse_inode_has_iomap(inode))
+			forget_all_cached_acls(inode);
 		fuse_change_attributes(inode, &outarg.attr, NULL,
 				       ATTR_TIMEOUT(&outarg),
 				       attr_version);
@@ -1470,7 +1471,8 @@ static int fuse_update_get_attr(struct mnt_idmap *idmap, struct inode *inode,
 		sync = time_before64(fi->i_time, get_jiffies_64());
 
 	if (sync) {
-		forget_all_cached_acls(inode);
+		if (!fuse_inode_has_iomap(inode))
+			forget_all_cached_acls(inode);
 		/* Try statx if a field not covered by regular stat is wanted */
 		if (!fc->no_statx && (request_mask & ~STATX_BASIC_STATS)) {
 			err = fuse_do_statx(idmap, inode, file, stat);
@@ -1648,6 +1650,9 @@ static int fuse_access(struct inode *inode, int mask)
 
 static int fuse_perm_getattr(struct inode *inode, int mask)
 {
+	if (fuse_inode_has_iomap(inode))
+		return 0;
+
 	if (mask & MAY_NOT_BLOCK)
 		return -ECHILD;
 
@@ -2325,7 +2330,7 @@ static int fuse_setattr(struct mnt_idmap *idmap, struct dentry *entry,
 		 * If filesystem supports acls it may have updated acl xattrs in
 		 * the filesystem, so forget cached acls for the inode.
 		 */
-		if (fc->posix_acl)
+		if (fc->posix_acl && !is_iomap)
 			forget_all_cached_acls(inode);
 
 		/* Directory mode changed, may need to revalidate access */
diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
index 45dd932eb03a5e..f7c2a45f23678e 100644
--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -224,7 +224,8 @@ static int fuse_direntplus_link(struct file *file,
 		fi->nlookup++;
 		spin_unlock(&fi->lock);
 
-		forget_all_cached_acls(inode);
+		if (!fuse_inode_has_iomap(inode))
+			forget_all_cached_acls(inode);
 		fuse_change_attributes(inode, &o->attr, NULL,
 				       ATTR_TIMEOUT(o),
 				       attr_version);

[PATCH 01/10] fuse: cache iomaps

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Cache iomaps to a file so that we don't have to upcall the server.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |   39 +
 fs/fuse/iomap_priv.h      |  135 ++++
 include/uapi/linux/fuse.h |    5 
 fs/fuse/Makefile          |    2 
 fs/fuse/file_iomap.c      |   23 +
 fs/fuse/iomap_cache.c     | 1629 +++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 1827 insertions(+), 6 deletions(-)
 create mode 100644 fs/fuse/iomap_cache.c


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index ae03a898d3aa7d..33b65253b2e9be 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -120,6 +120,24 @@ struct fuse_backing {
 	struct rcu_head rcu;
 };
 
+#if IS_ENABLED(CONFIG_FUSE_IOMAP)
+/*
+ * File incore extent information, present for each of data & attr forks.
+ */
+struct fuse_ifork {
+	int64_t			if_bytes;	/* bytes in if_data */
+	void			*if_data;	/* extent tree root */
+	int			if_height;	/* height of the extent tree */
+};
+
+struct fuse_iomap_cache {
+	struct fuse_ifork	im_read;
+	struct fuse_ifork	*im_write;
+	uint64_t		im_seq;		/* validity counter */
+	struct rw_semaphore	im_lock;	/* mapping lock */
+};
+#endif
+
 /** FUSE inode */
 struct fuse_inode {
 	/** Inode data */
@@ -185,6 +203,9 @@ struct fuse_inode {
 			spinlock_t ioend_lock;
 			struct work_struct ioend_work;
 			struct list_head ioend_list;
+
+			/* cached iomap mappings */
+			struct fuse_iomap_cache cache;
 #endif
 		};
 
@@ -261,6 +282,11 @@ enum {
 	FUSE_I_IOMAP,
 	/* Enable untorn writes */
 	FUSE_I_ATOMIC,
+	/*
+	 * Cache iomaps in the kernel.  This is required for any filesystem
+	 * that needs to synchronize pagecache write and writeback.
+	 */
+	FUSE_I_IOMAP_CACHE,
 };
 
 struct fuse_conn;
@@ -1816,6 +1842,18 @@ int fuse_iomap_dev_inval(struct fuse_conn *fc,
 			 const struct fuse_iomap_dev_inval_out *arg);
 
 int fuse_iomap_fadvise(struct file *file, loff_t start, loff_t end, int advice);
+
+static inline bool fuse_inode_caches_iomaps(const struct inode *inode)
+{
+	const struct fuse_inode *fi = get_fuse_inode_c(inode);
+
+	return test_bit(FUSE_I_IOMAP_CACHE, &fi->state);
+}
+
+enum fuse_iomap_iodir {
+	READ_MAPPING,
+	WRITE_MAPPING,
+};
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
@@ -1842,6 +1880,7 @@ int fuse_iomap_fadvise(struct file *file, loff_t start, loff_t end, int advice);
 # define fuse_dev_ioctl_iomap_support(...)	(-EOPNOTSUPP)
 # define fuse_iomap_dev_inval(...)		(-ENOSYS)
 # define fuse_iomap_fadvise			NULL
+# define fuse_inode_caches_iomaps(...)		(false)
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/fs/fuse/iomap_priv.h b/fs/fuse/iomap_priv.h
index 7002eb38f87fe1..8e4a32879025a4 100644
--- a/fs/fuse/iomap_priv.h
+++ b/fs/fuse/iomap_priv.h
@@ -1,5 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
+ * The fuse_iext code comes from xfs_iext_tree.[ch] and is:
+ * Copyright (c) 2017 Christoph Hellwig.
+ *
+ * Everything else is:
  * Copyright (C) 2025 Oracle.  All Rights Reserved.
  * Author: Darrick J. Wong <djwong@kernel.org>
  */
@@ -40,13 +44,134 @@ while (static_branch_unlikely(&fuse_iomap_debug)) {			\
 })
 #endif /* CONFIG_FUSE_IOMAP_DEBUG */
 
-enum fuse_iomap_iodir {
-	READ_MAPPING,
-	WRITE_MAPPING,
-};
-
 #define EFSCORRUPTED	EUCLEAN
 
+void fuse_iomap_cache_lock(struct inode *inode);
+void fuse_iomap_cache_unlock(struct inode *inode);
+void fuse_iomap_cache_lock_shared(struct inode *inode);
+void fuse_iomap_cache_unlock_shared(struct inode *inode);
+
+struct fuse_iext_leaf;
+
+struct fuse_iext_cursor {
+	struct fuse_iext_leaf	*leaf;
+	int			pos;
+};
+
+#define FUSE_IEXT_LEFT_CONTIG	(1u << 0)
+#define FUSE_IEXT_RIGHT_CONTIG	(1u << 1)
+#define FUSE_IEXT_LEFT_FILLING	(1u << 2)
+#define FUSE_IEXT_RIGHT_FILLING	(1u << 3)
+#define FUSE_IEXT_LEFT_VALID	(1u << 4)
+#define FUSE_IEXT_RIGHT_VALID	(1u << 5)
+#define FUSE_IEXT_WRITE_MAPPING	(1u << 6)
+
+struct fuse_ifork *fuse_iext_state_to_fork(struct fuse_iomap_cache *ip,
+		unsigned int state);
+
+uint64_t	fuse_iext_count(const struct fuse_ifork *ifp);
+void		fuse_iext_insert_raw(struct fuse_iomap_cache *ip,
+			struct fuse_ifork *ifp,
+			struct fuse_iext_cursor *cur,
+			const struct fuse_iomap_io *irec);
+void		fuse_iext_insert(struct fuse_iomap_cache *,
+			struct fuse_iext_cursor *cur,
+			const struct fuse_iomap_io *, int);
+void		fuse_iext_remove(struct fuse_iomap_cache *,
+			struct fuse_iext_cursor *,
+			int);
+void		fuse_iext_destroy(struct fuse_ifork *);
+
+bool		fuse_iext_lookup_extent(struct fuse_iomap_cache *ip,
+			struct fuse_ifork *ifp, loff_t bno,
+			struct fuse_iext_cursor *cur,
+			struct fuse_iomap_io *gotp);
+bool		fuse_iext_lookup_extent_before(struct fuse_iomap_cache *ip,
+			struct fuse_ifork *ifp, loff_t *end,
+			struct fuse_iext_cursor *cur,
+			struct fuse_iomap_io *gotp);
+bool		fuse_iext_get_extent(const struct fuse_ifork *ifp,
+			const struct fuse_iext_cursor *cur,
+			struct fuse_iomap_io *gotp);
+void		fuse_iext_update_extent(struct fuse_iomap_cache *ip, int state,
+			struct fuse_iext_cursor *cur,
+			struct fuse_iomap_io *gotp);
+
+void		fuse_iext_first(struct fuse_ifork *, struct fuse_iext_cursor *);
+void		fuse_iext_last(struct fuse_ifork *, struct fuse_iext_cursor *);
+void		fuse_iext_next(struct fuse_ifork *, struct fuse_iext_cursor *);
+void		fuse_iext_prev(struct fuse_ifork *, struct fuse_iext_cursor *);
+
+static inline bool fuse_iext_next_extent(struct fuse_ifork *ifp,
+		struct fuse_iext_cursor *cur, struct fuse_iomap_io *gotp)
+{
+	fuse_iext_next(ifp, cur);
+	return fuse_iext_get_extent(ifp, cur, gotp);
+}
+
+static inline bool fuse_iext_prev_extent(struct fuse_ifork *ifp,
+		struct fuse_iext_cursor *cur, struct fuse_iomap_io *gotp)
+{
+	fuse_iext_prev(ifp, cur);
+	return fuse_iext_get_extent(ifp, cur, gotp);
+}
+
+/*
+ * Return the extent after cur in gotp without updating the cursor.
+ */
+static inline bool fuse_iext_peek_next_extent(struct fuse_ifork *ifp,
+		struct fuse_iext_cursor *cur, struct fuse_iomap_io *gotp)
+{
+	struct fuse_iext_cursor ncur = *cur;
+
+	fuse_iext_next(ifp, &ncur);
+	return fuse_iext_get_extent(ifp, &ncur, gotp);
+}
+
+/*
+ * Return the extent before cur in gotp without updating the cursor.
+ */
+static inline bool fuse_iext_peek_prev_extent(struct fuse_ifork *ifp,
+		struct fuse_iext_cursor *cur, struct fuse_iomap_io *gotp)
+{
+	struct fuse_iext_cursor ncur = *cur;
+
+	fuse_iext_prev(ifp, &ncur);
+	return fuse_iext_get_extent(ifp, &ncur, gotp);
+}
+
+#define for_each_fuse_iext(ifp, ext, got)		\
+	for (fuse_iext_first((ifp), (ext));		\
+	     fuse_iext_get_extent((ifp), (ext), (got));	\
+	     fuse_iext_next((ifp), (ext)))
+
+static inline uint64_t fuse_iext_read_seq(struct fuse_iomap_cache *ip)
+{
+	return (uint64_t)READ_ONCE(ip->im_seq);
+}
+
+int fuse_iomap_cache_remove(struct inode *inode, enum fuse_iomap_iodir iodir,
+			    loff_t off, uint64_t len);
+
+int fuse_iomap_cache_upsert(struct inode *inode, enum fuse_iomap_iodir iodir,
+			    const struct fuse_iomap_io *map);
+
+enum fuse_iomap_lookup_result {
+	LOOKUP_HIT,
+	LOOKUP_MISS,
+	LOOKUP_NOFORK,
+};
+
+struct fuse_iomap_lookup {
+	struct fuse_iomap_io	map;		 /* cached mapping */
+	uint64_t		validity_cookie; /* used with .iomap_valid() */
+};
+
+enum fuse_iomap_lookup_result
+fuse_iomap_cache_lookup(struct inode *inode, enum fuse_iomap_iodir iodir,
+			loff_t off, uint64_t len,
+			struct fuse_iomap_lookup *mval);
+
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _FS_FUSE_IOMAP_PRIV_H */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 94ec220beb5f79..d4a257517915fd 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1358,6 +1358,8 @@ struct fuse_uring_cmd_req {
 
 /* fuse-specific mapping type indicating that writes use the read mapping */
 #define FUSE_IOMAP_TYPE_PURE_OVERWRITE	(255)
+/* fuse-specific mapping type saying the server has populated the cache */
+#define FUSE_IOMAP_TYPE_RETRY_CACHE	(254)
 
 #define FUSE_IOMAP_DEV_NULL		(0U)	/* null device cookie */
 
@@ -1500,4 +1502,7 @@ struct fuse_iomap_dev_inval_out {
 	uint64_t length;
 };
 
+/* invalidate all cached iomap mappings up to EOF */
+#define FUSE_IOMAP_INVAL_TO_EOF		(~0ULL)
+
 #endif /* _LINUX_FUSE_H */
diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 27be39317701d6..e3ed1da6cfb6e7 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -18,6 +18,6 @@ fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
 fuse-$(CONFIG_FUSE_BACKING) += backing.o
 fuse-$(CONFIG_SYSCTL) += sysctl.o
 fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
-fuse-$(CONFIG_FUSE_IOMAP) += file_iomap.o
+fuse-$(CONFIG_FUSE_IOMAP) += file_iomap.o iomap_cache.o
 
 virtiofs-y := virtio_fs.o
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 1fc9a9b7b75094..d35e69d03b0940 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1123,6 +1123,21 @@ static inline void fuse_inode_clear_atomic(struct inode *inode)
 	clear_bit(FUSE_I_ATOMIC, &fi->state);
 }
 
+static inline void fuse_iomap_clear_cache(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	clear_bit(FUSE_I_IOMAP_CACHE, &fi->state);
+
+	fuse_iext_destroy(&fi->cache.im_read);
+	if (fi->cache.im_write) {
+		fuse_iext_destroy(fi->cache.im_write);
+		kfree(fi->cache.im_write);
+	}
+}
+
 void fuse_iomap_init_inode(struct inode *inode, unsigned attr_flags)
 {
 	struct fuse_conn *conn = get_fuse_conn(inode);
@@ -1139,6 +1154,8 @@ void fuse_iomap_evict_inode(struct inode *inode)
 {
 	trace_fuse_iomap_evict_inode(inode);
 
+	if (fuse_inode_caches_iomaps(inode))
+		fuse_iomap_clear_cache(inode);
 	if (fuse_inode_has_atomic(inode))
 		fuse_inode_clear_atomic(inode);
 	if (fuse_inode_has_iomap(inode))
@@ -1785,6 +1802,12 @@ static inline void fuse_inode_set_iomap(struct inode *inode)
 		min_order = inode->i_blkbits - PAGE_SHIFT;
 
 	mapping_set_folio_min_order(inode->i_mapping, min_order);
+
+	memset(&fi->cache.im_read, 0, sizeof(fi->cache.im_read));
+	fi->cache.im_seq = 0;
+	fi->cache.im_write = NULL;
+
+	init_rwsem(&fi->cache.im_lock);
 	set_bit(FUSE_I_IOMAP, &fi->state);
 }
 
diff --git a/fs/fuse/iomap_cache.c b/fs/fuse/iomap_cache.c
new file mode 100644
index 00000000000000..1fec9dcc6d3922
--- /dev/null
+++ b/fs/fuse/iomap_cache.c
@@ -0,0 +1,1629 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fuse_iext* code adapted from xfs_iext_tree.c:
+ * Copyright (c) 2017 Christoph Hellwig.
+ *
+ * fuse_iomap_cache*lock* code adapted from xfs_inode.c:
+ * Copyright (c) 2000-2006 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ *
+ * Copyright (C) 2025 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "fuse_i.h"
+#include "iomap_priv.h"
+#include "fuse_trace.h"
+#include <linux/iomap.h>
+
+/* maximum length of a mapping that we're willing to cache */
+#define FUSE_IOMAP_MAX_LEN	((loff_t)(1ULL << 63))
+
+void fuse_iomap_cache_lock_shared(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_iomap_cache *ip = &fi->cache;
+
+	down_read(&ip->im_lock);
+}
+
+void fuse_iomap_cache_unlock_shared(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_iomap_cache *ip = &fi->cache;
+
+	up_read(&ip->im_lock);
+}
+
+void fuse_iomap_cache_lock(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_iomap_cache *ip = &fi->cache;
+
+	down_write(&ip->im_lock);
+}
+
+void fuse_iomap_cache_unlock(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_iomap_cache *ip = &fi->cache;
+
+	up_write(&ip->im_lock);
+}
+
+static inline void assert_cache_locked_shared(struct fuse_iomap_cache *ip)
+{
+	rwsem_assert_held(&ip->im_lock);
+}
+
+static inline void assert_cache_locked(struct fuse_iomap_cache *ip)
+{
+	rwsem_assert_held_write_nolockdep(&ip->im_lock);
+}
+
+static inline struct fuse_inode *FUSE_I(struct fuse_iomap_cache *ip)
+{
+	return container_of(ip, struct fuse_inode, cache);
+}
+
+static inline struct inode *VFS_I(struct fuse_iomap_cache *ip)
+{
+	struct fuse_inode *fi = FUSE_I(ip);
+
+	return &fi->inode;
+}
+
+static inline uint32_t
+fuse_iomap_fork_to_state(const struct fuse_iomap_cache *ip,
+			 const struct fuse_ifork *ifp)
+{
+	ASSERT(ifp == ip->im_write || ifp == &ip->im_read);
+
+	if (ifp == ip->im_write)
+		return FUSE_IEXT_WRITE_MAPPING;
+	return 0;
+}
+
+/* Convert bmap state flags to an inode fork. */
+struct fuse_ifork *
+fuse_iext_state_to_fork(
+	struct fuse_iomap_cache	*ip,
+	unsigned int		state)
+{
+	if (state & FUSE_IEXT_WRITE_MAPPING)
+		return ip->im_write;
+	return &ip->im_read;
+}
+
+/* The internal iext tree record is a struct fuse_iomap_io */
+
+static bool fuse_iext_rec_is_empty(const struct fuse_iomap_io *rec)
+{
+	return rec->length == 0;
+}
+
+static inline void fuse_iext_rec_clear(struct fuse_iomap_io *rec)
+{
+	memset(rec, 0, sizeof(*rec));
+}
+
+static void
+fuse_iext_set(
+	struct fuse_iomap_io		*rec,
+	const struct fuse_iomap_io	*irec)
+{
+	ASSERT(irec->length > 0);
+
+	*rec = *irec;
+}
+
+static void
+fuse_iext_get(
+	struct fuse_iomap_io		*irec,
+	const struct fuse_iomap_io	*rec)
+{
+	*irec = *rec;
+}
+
+enum {
+	NODE_SIZE	= 256,
+	KEYS_PER_NODE	= NODE_SIZE / (sizeof(uint64_t) + sizeof(void *)),
+	RECS_PER_LEAF	= (NODE_SIZE - (2 * sizeof(struct fuse_iext_leaf *))) /
+				sizeof(struct fuse_iomap_io),
+};
+
+/*
+ * In-core extent btree block layout:
+ *
+ * There are two types of blocks in the btree: leaf and inner (non-leaf) blocks.
+ *
+ * The leaf blocks are made up by %KEYS_PER_NODE extent records, which each
+ * contain the startoffset, blockcount, startblock and unwritten extent flag.
+ * See above for the exact format, followed by pointers to the previous and next
+ * leaf blocks (if there are any).
+ *
+ * The inner (non-leaf) blocks first contain KEYS_PER_NODE lookup keys, followed
+ * by an equal number of pointers to the btree blocks at the next lower level.
+ *
+ *		+-------+-------+-------+-------+-------+----------+----------+
+ * Leaf:	| rec 1 | rec 2 | rec 3 | rec 4 | rec N | prev-ptr | next-ptr |
+ *		+-------+-------+-------+-------+-------+----------+----------+
+ *
+ *		+-------+-------+-------+-------+-------+-------+------+-------+
+ * Inner:	| key 1 | key 2 | key 3 | key N | ptr 1 | ptr 2 | ptr3 | ptr N |
+ *		+-------+-------+-------+-------+-------+-------+------+-------+
+ */
+struct fuse_iext_node {
+	uint64_t		keys[KEYS_PER_NODE];
+#define FUSE_IEXT_KEY_INVALID	(1ULL << 63)
+	void			*ptrs[KEYS_PER_NODE];
+};
+
+struct fuse_iext_leaf {
+	struct fuse_iomap_io	recs[RECS_PER_LEAF];
+	struct fuse_iext_leaf	*prev;
+	struct fuse_iext_leaf	*next;
+};
+
+inline uint64_t fuse_iext_count(const struct fuse_ifork *ifp)
+{
+	return ifp->if_bytes / sizeof(struct fuse_iomap_io);
+}
+
+static inline int fuse_iext_max_recs(const struct fuse_ifork *ifp)
+{
+	if (ifp->if_height == 1)
+		return fuse_iext_count(ifp);
+	return RECS_PER_LEAF;
+}
+
+static inline struct fuse_iomap_io *cur_rec(const struct fuse_iext_cursor *cur)
+{
+	return &cur->leaf->recs[cur->pos];
+}
+
+static inline bool fuse_iext_valid(const struct fuse_ifork *ifp,
+				   const struct fuse_iext_cursor *cur)
+{
+	if (!cur->leaf)
+		return false;
+	if (cur->pos < 0 || cur->pos >= fuse_iext_max_recs(ifp))
+		return false;
+	if (fuse_iext_rec_is_empty(cur_rec(cur)))
+		return false;
+	return true;
+}
+
+static void *
+fuse_iext_find_first_leaf(
+	struct fuse_ifork	*ifp)
+{
+	struct fuse_iext_node	*node = ifp->if_data;
+	int			height;
+
+	if (!ifp->if_height)
+		return NULL;
+
+	for (height = ifp->if_height; height > 1; height--) {
+		node = node->ptrs[0];
+		ASSERT(node);
+	}
+
+	return node;
+}
+
+static void *
+fuse_iext_find_last_leaf(
+	struct fuse_ifork	*ifp)
+{
+	struct fuse_iext_node	*node = ifp->if_data;
+	int			height, i;
+
+	if (!ifp->if_height)
+		return NULL;
+
+	for (height = ifp->if_height; height > 1; height--) {
+		for (i = 1; i < KEYS_PER_NODE; i++)
+			if (!node->ptrs[i])
+				break;
+		node = node->ptrs[i - 1];
+		ASSERT(node);
+	}
+
+	return node;
+}
+
+void
+fuse_iext_first(
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_cursor	*cur)
+{
+	cur->pos = 0;
+	cur->leaf = fuse_iext_find_first_leaf(ifp);
+}
+
+void
+fuse_iext_last(
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_cursor	*cur)
+{
+	int			i;
+
+	cur->leaf = fuse_iext_find_last_leaf(ifp);
+	if (!cur->leaf) {
+		cur->pos = 0;
+		return;
+	}
+
+	for (i = 1; i < fuse_iext_max_recs(ifp); i++) {
+		if (fuse_iext_rec_is_empty(&cur->leaf->recs[i]))
+			break;
+	}
+	cur->pos = i - 1;
+}
+
+void
+fuse_iext_next(
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_cursor	*cur)
+{
+	if (!cur->leaf) {
+		ASSERT(cur->pos <= 0 || cur->pos >= RECS_PER_LEAF);
+		fuse_iext_first(ifp, cur);
+		return;
+	}
+
+	ASSERT(cur->pos >= 0);
+	ASSERT(cur->pos < fuse_iext_max_recs(ifp));
+
+	cur->pos++;
+	if (ifp->if_height > 1 && !fuse_iext_valid(ifp, cur) &&
+	    cur->leaf->next) {
+		cur->leaf = cur->leaf->next;
+		cur->pos = 0;
+	}
+}
+
+void
+fuse_iext_prev(
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_cursor	*cur)
+{
+	if (!cur->leaf) {
+		ASSERT(cur->pos <= 0 || cur->pos >= RECS_PER_LEAF);
+		fuse_iext_last(ifp, cur);
+		return;
+	}
+
+	ASSERT(cur->pos >= 0);
+	ASSERT(cur->pos <= RECS_PER_LEAF);
+
+recurse:
+	do {
+		cur->pos--;
+		if (fuse_iext_valid(ifp, cur))
+			return;
+	} while (cur->pos > 0);
+
+	if (ifp->if_height > 1 && cur->leaf->prev) {
+		cur->leaf = cur->leaf->prev;
+		cur->pos = RECS_PER_LEAF;
+		goto recurse;
+	}
+}
+
+static inline int
+fuse_iext_key_cmp(
+	struct fuse_iext_node	*node,
+	int			n,
+	loff_t			offset)
+{
+	if (node->keys[n] > offset)
+		return 1;
+	if (node->keys[n] < offset)
+		return -1;
+	return 0;
+}
+
+static inline int
+fuse_iext_rec_cmp(
+	struct fuse_iomap_io	*rec,
+	loff_t			offset)
+{
+	if (rec->offset > offset)
+		return 1;
+	if (rec->offset + rec->length <= offset)
+		return -1;
+	return 0;
+}
+
+static void *
+fuse_iext_find_level(
+	struct fuse_ifork	*ifp,
+	loff_t			offset,
+	int			level)
+{
+	struct fuse_iext_node	*node = ifp->if_data;
+	int			height, i;
+
+	if (!ifp->if_height)
+		return NULL;
+
+	for (height = ifp->if_height; height > level; height--) {
+		for (i = 1; i < KEYS_PER_NODE; i++)
+			if (fuse_iext_key_cmp(node, i, offset) > 0)
+				break;
+
+		node = node->ptrs[i - 1];
+		if (!node)
+			break;
+	}
+
+	return node;
+}
+
+static int
+fuse_iext_node_pos(
+	struct fuse_iext_node	*node,
+	loff_t			offset)
+{
+	int			i;
+
+	for (i = 1; i < KEYS_PER_NODE; i++) {
+		if (fuse_iext_key_cmp(node, i, offset) > 0)
+			break;
+	}
+
+	return i - 1;
+}
+
+static int
+fuse_iext_node_insert_pos(
+	struct fuse_iext_node	*node,
+	loff_t			offset)
+{
+	int			i;
+
+	for (i = 0; i < KEYS_PER_NODE; i++) {
+		if (fuse_iext_key_cmp(node, i, offset) > 0)
+			return i;
+	}
+
+	return KEYS_PER_NODE;
+}
+
+static int
+fuse_iext_node_nr_entries(
+	struct fuse_iext_node	*node,
+	int			start)
+{
+	int			i;
+
+	for (i = start; i < KEYS_PER_NODE; i++) {
+		if (node->keys[i] == FUSE_IEXT_KEY_INVALID)
+			break;
+	}
+
+	return i;
+}
+
+static int
+fuse_iext_leaf_nr_entries(
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_leaf	*leaf,
+	int			start)
+{
+	int			i;
+
+	for (i = start; i < fuse_iext_max_recs(ifp); i++) {
+		if (fuse_iext_rec_is_empty(&leaf->recs[i]))
+			break;
+	}
+
+	return i;
+}
+
+static inline uint64_t
+fuse_iext_leaf_key(
+	struct fuse_iext_leaf	*leaf,
+	int			n)
+{
+	return leaf->recs[n].offset;
+}
+
+static inline void *
+fuse_iext_alloc_node(
+	int	size)
+{
+	return kzalloc(size, GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+}
+
+static void
+fuse_iext_grow(
+	struct fuse_ifork	*ifp)
+{
+	struct fuse_iext_node	*node = fuse_iext_alloc_node(NODE_SIZE);
+	int			i;
+
+	if (ifp->if_height == 1) {
+		struct fuse_iext_leaf *prev = ifp->if_data;
+
+		node->keys[0] = fuse_iext_leaf_key(prev, 0);
+		node->ptrs[0] = prev;
+	} else  {
+		struct fuse_iext_node *prev = ifp->if_data;
+
+		ASSERT(ifp->if_height > 1);
+
+		node->keys[0] = prev->keys[0];
+		node->ptrs[0] = prev;
+	}
+
+	for (i = 1; i < KEYS_PER_NODE; i++)
+		node->keys[i] = FUSE_IEXT_KEY_INVALID;
+
+	ifp->if_data = node;
+	ifp->if_height++;
+}
+
+static void
+fuse_iext_update_node(
+	struct fuse_ifork	*ifp,
+	loff_t			old_offset,
+	loff_t			new_offset,
+	int			level,
+	void			*ptr)
+{
+	struct fuse_iext_node	*node = ifp->if_data;
+	int			height, i;
+
+	for (height = ifp->if_height; height > level; height--) {
+		for (i = 0; i < KEYS_PER_NODE; i++) {
+			if (i > 0 && fuse_iext_key_cmp(node, i, old_offset) > 0)
+				break;
+			if (node->keys[i] == old_offset)
+				node->keys[i] = new_offset;
+		}
+		node = node->ptrs[i - 1];
+		ASSERT(node);
+	}
+
+	ASSERT(node == ptr);
+}
+
+static struct fuse_iext_node *
+fuse_iext_split_node(
+	struct fuse_iext_node	**nodep,
+	int			*pos,
+	int			*nr_entries)
+{
+	struct fuse_iext_node	*node = *nodep;
+	struct fuse_iext_node	*new = fuse_iext_alloc_node(NODE_SIZE);
+	const int		nr_move = KEYS_PER_NODE / 2;
+	int			nr_keep = nr_move + (KEYS_PER_NODE & 1);
+	int			i = 0;
+
+	/* for sequential append operations just spill over into the new node */
+	if (*pos == KEYS_PER_NODE) {
+		*nodep = new;
+		*pos = 0;
+		*nr_entries = 0;
+		goto done;
+	}
+
+
+	for (i = 0; i < nr_move; i++) {
+		new->keys[i] = node->keys[nr_keep + i];
+		new->ptrs[i] = node->ptrs[nr_keep + i];
+
+		node->keys[nr_keep + i] = FUSE_IEXT_KEY_INVALID;
+		node->ptrs[nr_keep + i] = NULL;
+	}
+
+	if (*pos >= nr_keep) {
+		*nodep = new;
+		*pos -= nr_keep;
+		*nr_entries = nr_move;
+	} else {
+		*nr_entries = nr_keep;
+	}
+done:
+	for (; i < KEYS_PER_NODE; i++)
+		new->keys[i] = FUSE_IEXT_KEY_INVALID;
+	return new;
+}
+
+static void
+fuse_iext_insert_node(
+	struct fuse_ifork	*ifp,
+	uint64_t		offset,
+	void			*ptr,
+	int			level)
+{
+	struct fuse_iext_node	*node, *new;
+	int			i, pos, nr_entries;
+
+again:
+	if (ifp->if_height < level)
+		fuse_iext_grow(ifp);
+
+	new = NULL;
+	node = fuse_iext_find_level(ifp, offset, level);
+	pos = fuse_iext_node_insert_pos(node, offset);
+	nr_entries = fuse_iext_node_nr_entries(node, pos);
+
+	ASSERT(pos >= nr_entries || fuse_iext_key_cmp(node, pos, offset) != 0);
+	ASSERT(nr_entries <= KEYS_PER_NODE);
+
+	if (nr_entries == KEYS_PER_NODE)
+		new = fuse_iext_split_node(&node, &pos, &nr_entries);
+
+	/*
+	 * Update the pointers in higher levels if the first entry changes
+	 * in an existing node.
+	 */
+	if (node != new && pos == 0 && nr_entries > 0)
+		fuse_iext_update_node(ifp, node->keys[0], offset, level, node);
+
+	for (i = nr_entries; i > pos; i--) {
+		node->keys[i] = node->keys[i - 1];
+		node->ptrs[i] = node->ptrs[i - 1];
+	}
+	node->keys[pos] = offset;
+	node->ptrs[pos] = ptr;
+
+	if (new) {
+		offset = new->keys[0];
+		ptr = new;
+		level++;
+		goto again;
+	}
+}
+
+static struct fuse_iext_leaf *
+fuse_iext_split_leaf(
+	struct fuse_iext_cursor	*cur,
+	int			*nr_entries)
+{
+	struct fuse_iext_leaf	*leaf = cur->leaf;
+	struct fuse_iext_leaf	*new = fuse_iext_alloc_node(NODE_SIZE);
+	const int		nr_move = RECS_PER_LEAF / 2;
+	int			nr_keep = nr_move + (RECS_PER_LEAF & 1);
+	int			i;
+
+	/* for sequential append operations just spill over into the new node */
+	if (cur->pos == RECS_PER_LEAF) {
+		cur->leaf = new;
+		cur->pos = 0;
+		*nr_entries = 0;
+		goto done;
+	}
+
+	for (i = 0; i < nr_move; i++) {
+		new->recs[i] = leaf->recs[nr_keep + i];
+		fuse_iext_rec_clear(&leaf->recs[nr_keep + i]);
+	}
+
+	if (cur->pos >= nr_keep) {
+		cur->leaf = new;
+		cur->pos -= nr_keep;
+		*nr_entries = nr_move;
+	} else {
+		*nr_entries = nr_keep;
+	}
+done:
+	if (leaf->next)
+		leaf->next->prev = new;
+	new->next = leaf->next;
+	new->prev = leaf;
+	leaf->next = new;
+	return new;
+}
+
+static void
+fuse_iext_alloc_root(
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_cursor	*cur)
+{
+	ASSERT(ifp->if_bytes == 0);
+
+	ifp->if_data = fuse_iext_alloc_node(sizeof(struct fuse_iomap_io));
+	ifp->if_height = 1;
+
+	/* now that we have a node step into it */
+	cur->leaf = ifp->if_data;
+	cur->pos = 0;
+}
+
+static void
+fuse_iext_realloc_root(
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_cursor	*cur)
+{
+	int64_t new_size = ifp->if_bytes + sizeof(struct fuse_iomap_io);
+	void *new;
+
+	/* account for the prev/next pointers */
+	if (new_size / sizeof(struct fuse_iomap_io) == RECS_PER_LEAF)
+		new_size = NODE_SIZE;
+
+	new = krealloc(ifp->if_data, new_size,
+			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+	memset(new + ifp->if_bytes, 0, new_size - ifp->if_bytes);
+	ifp->if_data = new;
+	cur->leaf = new;
+}
+
+/*
+ * Increment the sequence counter on extent tree changes. We use WRITE_ONCE
+ * here to ensure the update to the sequence counter is seen before the
+ * modifications to the extent tree itself take effect.
+ */
+static inline void fuse_iext_inc_seq(struct fuse_iomap_cache *ip)
+{
+	WRITE_ONCE(ip->im_seq, READ_ONCE(ip->im_seq) + 1);
+}
+
+void
+fuse_iext_insert_raw(
+	struct fuse_iomap_cache		*ip,
+	struct fuse_ifork		*ifp,
+	struct fuse_iext_cursor		*cur,
+	const struct fuse_iomap_io	*irec)
+{
+	loff_t				offset = irec->offset;
+	struct fuse_iext_leaf		*new = NULL;
+	int				nr_entries, i;
+
+	fuse_iext_inc_seq(ip);
+
+	if (ifp->if_height == 0)
+		fuse_iext_alloc_root(ifp, cur);
+	else if (ifp->if_height == 1)
+		fuse_iext_realloc_root(ifp, cur);
+
+	nr_entries = fuse_iext_leaf_nr_entries(ifp, cur->leaf, cur->pos);
+	ASSERT(nr_entries <= RECS_PER_LEAF);
+	ASSERT(cur->pos >= nr_entries ||
+	       fuse_iext_rec_cmp(cur_rec(cur), irec->offset) != 0);
+
+	if (nr_entries == RECS_PER_LEAF)
+		new = fuse_iext_split_leaf(cur, &nr_entries);
+
+	/*
+	 * Update the pointers in higher levels if the first entry changes
+	 * in an existing node.
+	 */
+	if (cur->leaf != new && cur->pos == 0 && nr_entries > 0) {
+		fuse_iext_update_node(ifp, fuse_iext_leaf_key(cur->leaf, 0),
+				offset, 1, cur->leaf);
+	}
+
+	for (i = nr_entries; i > cur->pos; i--)
+		cur->leaf->recs[i] = cur->leaf->recs[i - 1];
+	fuse_iext_set(cur_rec(cur), irec);
+	ifp->if_bytes += sizeof(struct fuse_iomap_io);
+
+	if (new)
+		fuse_iext_insert_node(ifp, fuse_iext_leaf_key(new, 0), new, 2);
+}
+
+void
+fuse_iext_insert(
+	struct fuse_iomap_cache		*ip,
+	struct fuse_iext_cursor		*cur,
+	const struct fuse_iomap_io	*irec,
+	int				state)
+{
+	struct fuse_ifork		*ifp = fuse_iext_state_to_fork(ip, state);
+
+	fuse_iext_insert_raw(ip, ifp, cur, irec);
+}
+
+static struct fuse_iext_node *
+fuse_iext_rebalance_node(
+	struct fuse_iext_node	*parent,
+	int			*pos,
+	struct fuse_iext_node	*node,
+	int			nr_entries)
+{
+	/*
+	 * If the neighbouring nodes are completely full, or have different
+	 * parents, we might never be able to merge our node, and will only
+	 * delete it once the number of entries hits zero.
+	 */
+	if (nr_entries == 0)
+		return node;
+
+	if (*pos > 0) {
+		struct fuse_iext_node *prev = parent->ptrs[*pos - 1];
+		int nr_prev = fuse_iext_node_nr_entries(prev, 0), i;
+
+		if (nr_prev + nr_entries <= KEYS_PER_NODE) {
+			for (i = 0; i < nr_entries; i++) {
+				prev->keys[nr_prev + i] = node->keys[i];
+				prev->ptrs[nr_prev + i] = node->ptrs[i];
+			}
+			return node;
+		}
+	}
+
+	if (*pos + 1 < fuse_iext_node_nr_entries(parent, *pos)) {
+		struct fuse_iext_node *next = parent->ptrs[*pos + 1];
+		int nr_next = fuse_iext_node_nr_entries(next, 0), i;
+
+		if (nr_entries + nr_next <= KEYS_PER_NODE) {
+			/*
+			 * Merge the next node into this node so that we don't
+			 * have to do an additional update of the keys in the
+			 * higher levels.
+			 */
+			for (i = 0; i < nr_next; i++) {
+				node->keys[nr_entries + i] = next->keys[i];
+				node->ptrs[nr_entries + i] = next->ptrs[i];
+			}
+
+			++*pos;
+			return next;
+		}
+	}
+
+	return NULL;
+}
+
+static void
+fuse_iext_remove_node(
+	struct fuse_ifork	*ifp,
+	loff_t			offset,
+	void			*victim)
+{
+	struct fuse_iext_node	*node, *parent;
+	int			level = 2, pos, nr_entries, i;
+
+	ASSERT(level <= ifp->if_height);
+	node = fuse_iext_find_level(ifp, offset, level);
+	pos = fuse_iext_node_pos(node, offset);
+again:
+	ASSERT(node->ptrs[pos]);
+	ASSERT(node->ptrs[pos] == victim);
+	kfree(victim);
+
+	nr_entries = fuse_iext_node_nr_entries(node, pos) - 1;
+	offset = node->keys[0];
+	for (i = pos; i < nr_entries; i++) {
+		node->keys[i] = node->keys[i + 1];
+		node->ptrs[i] = node->ptrs[i + 1];
+	}
+	node->keys[nr_entries] = FUSE_IEXT_KEY_INVALID;
+	node->ptrs[nr_entries] = NULL;
+
+	if (pos == 0 && nr_entries > 0) {
+		fuse_iext_update_node(ifp, offset, node->keys[0], level, node);
+		offset = node->keys[0];
+	}
+
+	if (nr_entries >= KEYS_PER_NODE / 2)
+		return;
+
+	if (level < ifp->if_height) {
+		/*
+		 * If we aren't at the root yet try to find a neighbour node to
+		 * merge with (or delete the node if it is empty), and then
+		 * recurse up to the next level.
+		 */
+		level++;
+		parent = fuse_iext_find_level(ifp, offset, level);
+		pos = fuse_iext_node_pos(parent, offset);
+
+		ASSERT(pos != KEYS_PER_NODE);
+		ASSERT(parent->ptrs[pos] == node);
+
+		node = fuse_iext_rebalance_node(parent, &pos, node, nr_entries);
+		if (node) {
+			victim = node;
+			node = parent;
+			goto again;
+		}
+	} else if (nr_entries == 1) {
+		/*
+		 * If we are at the root and only one entry is left we can just
+		 * free this node and update the root pointer.
+		 */
+		ASSERT(node == ifp->if_data);
+		ifp->if_data = node->ptrs[0];
+		ifp->if_height--;
+		kfree(node);
+	}
+}
+
+static void
+fuse_iext_rebalance_leaf(
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_cursor	*cur,
+	struct fuse_iext_leaf	*leaf,
+	loff_t			offset,
+	int			nr_entries)
+{
+	/*
+	 * If the neighbouring nodes are completely full we might never be able
+	 * to merge our node, and will only delete it once the number of
+	 * entries hits zero.
+	 */
+	if (nr_entries == 0)
+		goto remove_node;
+
+	if (leaf->prev) {
+		int nr_prev = fuse_iext_leaf_nr_entries(ifp, leaf->prev, 0), i;
+
+		if (nr_prev + nr_entries <= RECS_PER_LEAF) {
+			for (i = 0; i < nr_entries; i++)
+				leaf->prev->recs[nr_prev + i] = leaf->recs[i];
+
+			if (cur->leaf == leaf) {
+				cur->leaf = leaf->prev;
+				cur->pos += nr_prev;
+			}
+			goto remove_node;
+		}
+	}
+
+	if (leaf->next) {
+		int nr_next = fuse_iext_leaf_nr_entries(ifp, leaf->next, 0), i;
+
+		if (nr_entries + nr_next <= RECS_PER_LEAF) {
+			/*
+			 * Merge the next node into this node so that we don't
+			 * have to do an additional update of the keys in the
+			 * higher levels.
+			 */
+			for (i = 0; i < nr_next; i++) {
+				leaf->recs[nr_entries + i] =
+					leaf->next->recs[i];
+			}
+
+			if (cur->leaf == leaf->next) {
+				cur->leaf = leaf;
+				cur->pos += nr_entries;
+			}
+
+			offset = fuse_iext_leaf_key(leaf->next, 0);
+			leaf = leaf->next;
+			goto remove_node;
+		}
+	}
+
+	return;
+remove_node:
+	if (leaf->prev)
+		leaf->prev->next = leaf->next;
+	if (leaf->next)
+		leaf->next->prev = leaf->prev;
+	fuse_iext_remove_node(ifp, offset, leaf);
+}
+
+static void
+fuse_iext_free_last_leaf(
+	struct fuse_ifork	*ifp)
+{
+	ifp->if_height--;
+	kfree(ifp->if_data);
+	ifp->if_data = NULL;
+}
+
+void
+fuse_iext_remove(
+	struct fuse_iomap_cache	*ip,
+	struct fuse_iext_cursor	*cur,
+	int			state)
+{
+	struct fuse_ifork	*ifp = fuse_iext_state_to_fork(ip, state);
+	struct fuse_iext_leaf	*leaf = cur->leaf;
+	loff_t			offset = fuse_iext_leaf_key(leaf, 0);
+	int			i, nr_entries;
+
+	ASSERT(ifp->if_height > 0);
+	ASSERT(ifp->if_data != NULL);
+	ASSERT(fuse_iext_valid(ifp, cur));
+
+	fuse_iext_inc_seq(ip);
+
+	nr_entries = fuse_iext_leaf_nr_entries(ifp, leaf, cur->pos) - 1;
+	for (i = cur->pos; i < nr_entries; i++)
+		leaf->recs[i] = leaf->recs[i + 1];
+	fuse_iext_rec_clear(&leaf->recs[nr_entries]);
+	ifp->if_bytes -= sizeof(struct fuse_iomap_io);
+
+	if (cur->pos == 0 && nr_entries > 0) {
+		fuse_iext_update_node(ifp, offset, fuse_iext_leaf_key(leaf, 0), 1,
+				leaf);
+		offset = fuse_iext_leaf_key(leaf, 0);
+	} else if (cur->pos == nr_entries) {
+		if (ifp->if_height > 1 && leaf->next)
+			cur->leaf = leaf->next;
+		else
+			cur->leaf = NULL;
+		cur->pos = 0;
+	}
+
+	if (nr_entries >= RECS_PER_LEAF / 2)
+		return;
+
+	if (ifp->if_height > 1)
+		fuse_iext_rebalance_leaf(ifp, cur, leaf, offset, nr_entries);
+	else if (nr_entries == 0)
+		fuse_iext_free_last_leaf(ifp);
+}
+
+/*
+ * Lookup the extent covering offset.
+ *
+ * If there is an extent covering offset return the extent index, and store the
+ * expanded extent structure in *gotp, and the extent cursor in *cur.
+ * If there is no extent covering offset, but there is an extent after it (e.g.
+ * it lies in a hole) return that extent in *gotp and its cursor in *cur
+ * instead.
+ * If offset is beyond the last extent return false, and return an invalid
+ * cursor value.
+ */
+bool
+fuse_iext_lookup_extent(
+	struct fuse_iomap_cache	*ip,
+	struct fuse_ifork	*ifp,
+	loff_t			offset,
+	struct fuse_iext_cursor	*cur,
+	struct fuse_iomap_io	*gotp)
+{
+	cur->leaf = fuse_iext_find_level(ifp, offset, 1);
+	if (!cur->leaf) {
+		cur->pos = 0;
+		return false;
+	}
+
+	for (cur->pos = 0; cur->pos < fuse_iext_max_recs(ifp); cur->pos++) {
+		struct fuse_iomap_io *rec = cur_rec(cur);
+
+		if (fuse_iext_rec_is_empty(rec))
+			break;
+		if (fuse_iext_rec_cmp(rec, offset) >= 0)
+			goto found;
+	}
+
+	/* Try looking in the next node for an entry > offset */
+	if (ifp->if_height == 1 || !cur->leaf->next)
+		return false;
+	cur->leaf = cur->leaf->next;
+	cur->pos = 0;
+	if (!fuse_iext_valid(ifp, cur))
+		return false;
+found:
+	fuse_iext_get(gotp, cur_rec(cur));
+	return true;
+}
+
+/*
+ * Returns the last extent before end, and if this extent doesn't cover
+ * end, update end to the end of the extent.
+ */
+bool
+fuse_iext_lookup_extent_before(
+	struct fuse_iomap_cache	*ip,
+	struct fuse_ifork	*ifp,
+	loff_t			*end,
+	struct fuse_iext_cursor	*cur,
+	struct fuse_iomap_io	*gotp)
+{
+	/* could be optimized to not even look up the next on a match.. */
+	if (fuse_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
+	    gotp->offset <= *end - 1)
+		return true;
+	if (!fuse_iext_prev_extent(ifp, cur, gotp))
+		return false;
+	*end = gotp->offset + gotp->length;
+	return true;
+}
+
+void
+fuse_iext_update_extent(
+	struct fuse_iomap_cache	*ip,
+	int			state,
+	struct fuse_iext_cursor	*cur,
+	struct fuse_iomap_io	*new)
+{
+	struct fuse_ifork	*ifp = fuse_iext_state_to_fork(ip, state);
+
+	fuse_iext_inc_seq(ip);
+
+	if (cur->pos == 0) {
+		struct fuse_iomap_io	old;
+
+		fuse_iext_get(&old, cur_rec(cur));
+		if (new->offset != old.offset) {
+			fuse_iext_update_node(ifp, old.offset,
+					new->offset, 1, cur->leaf);
+		}
+	}
+
+	fuse_iext_set(cur_rec(cur), new);
+}
+
+/*
+ * Return true if the cursor points at an extent and return the extent structure
+ * in gotp.  Else return false.
+ */
+bool
+fuse_iext_get_extent(
+	const struct fuse_ifork		*ifp,
+	const struct fuse_iext_cursor	*cur,
+	struct fuse_iomap_io		*gotp)
+{
+	if (!fuse_iext_valid(ifp, cur))
+		return false;
+	fuse_iext_get(gotp, cur_rec(cur));
+	return true;
+}
+
+/*
+ * This is a recursive function, because of that we need to be extremely
+ * careful with stack usage.
+ */
+static void
+fuse_iext_destroy_node(
+	struct fuse_iext_node	*node,
+	int			level)
+{
+	int			i;
+
+	if (level > 1) {
+		for (i = 0; i < KEYS_PER_NODE; i++) {
+			if (node->keys[i] == FUSE_IEXT_KEY_INVALID)
+				break;
+			fuse_iext_destroy_node(node->ptrs[i], level - 1);
+		}
+	}
+
+	kfree(node);
+}
+
+void
+fuse_iext_destroy(
+	struct fuse_ifork	*ifp)
+{
+	fuse_iext_destroy_node(ifp->if_data, ifp->if_height);
+
+	ifp->if_bytes = 0;
+	ifp->if_height = 0;
+	ifp->if_data = NULL;
+}
+
+static inline struct fuse_ifork *
+fuse_iomap_fork_ptr(
+	struct fuse_iomap_cache	*ip,
+	enum fuse_iomap_iodir	iodir)
+{
+	switch (iodir) {
+	case READ_MAPPING:
+		return &ip->im_read;
+	case WRITE_MAPPING:
+		return ip->im_write;
+	default:
+		ASSERT(0);
+		return NULL;
+	}
+}
+
+static inline bool fuse_iomap_addrs_adjacent(const struct fuse_iomap_io *left,
+					     const struct fuse_iomap_io *right)
+{
+	switch (left->type) {
+	case FUSE_IOMAP_TYPE_MAPPED:
+	case FUSE_IOMAP_TYPE_UNWRITTEN:
+		return left->addr + left->length == right->addr;
+	default:
+		return left->addr  == FUSE_IOMAP_NULL_ADDR &&
+		       right->addr == FUSE_IOMAP_NULL_ADDR;
+	}
+}
+
+static inline bool fuse_iomap_can_merge(const struct fuse_iomap_io *left,
+					const struct fuse_iomap_io *right)
+{
+	return (left->dev == right->dev &&
+		left->offset + left->length == right->offset &&
+		left->type  == right->type &&
+		fuse_iomap_addrs_adjacent(left, right) &&
+		left->flags == right->flags &&
+		left->length + right->length <= FUSE_IOMAP_MAX_LEN);
+}
+
+static inline bool fuse_iomap_can_merge3(const struct fuse_iomap_io *left,
+					 const struct fuse_iomap_io *new,
+					 const struct fuse_iomap_io *right)
+{
+	return left->length + new->length + right->length <= FUSE_IOMAP_MAX_LEN;
+}
+
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
+static void fuse_iext_check_mappings(struct inode *inode,
+				      struct fuse_iomap_cache *ip,
+				      struct fuse_ifork *ifp)
+{
+	struct fuse_inode	*fi = FUSE_I(ip);
+	struct fuse_iext_cursor	icur;
+	struct fuse_iomap_io	prev, got;
+	unsigned long long	nr = 0;
+
+	if (!ifp || !static_branch_unlikely(&fuse_iomap_debug))
+		return;
+
+	fuse_iext_first(ifp, &icur);
+	if (!fuse_iext_get_extent(ifp, &icur, &prev))
+		return;
+	nr++;
+
+	fuse_iext_next(ifp, &icur);
+	while (fuse_iext_get_extent(ifp, &icur, &got)) {
+		if (got.length == 0 ||
+		    got.offset < prev.offset + prev.length ||
+		    fuse_iomap_can_merge(&prev, &got)) {
+			printk(KERN_ERR "FUSE IOMAP CORRUPTION ino=%llu nr=%llu",
+			       fi->orig_ino, nr);
+			printk(KERN_ERR "prev: offset=%llu length=%llu type=%u flags=0x%x dev=%u addr=%llu\n",
+			       prev.offset, prev.length, prev.type, prev.flags,
+			       prev.dev, prev.addr);
+			printk(KERN_ERR "curr: offset=%llu length=%llu type=%u flags=0x%x dev=%u addr=%llu\n",
+			       got.offset, got.length, got.type, got.flags,
+			       got.dev, got.addr);
+		}
+
+		prev = got;
+		nr++;
+		fuse_iext_next(ifp, &icur);
+	}
+}
+#else
+# define fuse_iext_check_mappings(...)	((void)0)
+#endif
+
+static void
+fuse_iext_del_mapping(
+	struct fuse_iomap_cache	*ip,
+	struct fuse_ifork	*ifp,
+	struct fuse_iext_cursor	*icur,
+	struct fuse_iomap_io	*got,	/* current extent entry */
+	struct fuse_iomap_io	*del)	/* data to remove from extents */
+{
+	struct fuse_iomap_io	new;	/* new record to be inserted */
+	/* first addr (fsblock aligned) past del */
+	uint64_t		del_endaddr;
+	/* first offset (fsblock aligned) past del */
+	uint64_t		del_endoff = del->offset + del->length;
+	/* first offset (fsblock aligned) past got */
+	uint64_t		got_endoff = got->offset + got->length;
+	uint32_t		state = fuse_iomap_fork_to_state(ip, ifp);
+
+	ASSERT(del->length > 0);
+	ASSERT(got->offset <= del->offset);
+	ASSERT(got_endoff >= del_endoff);
+
+	switch (del->type) {
+	case FUSE_IOMAP_TYPE_MAPPED:
+	case FUSE_IOMAP_TYPE_UNWRITTEN:
+		del_endaddr = del->addr + del->length;
+		break;
+	default:
+		del_endaddr = FUSE_IOMAP_NULL_ADDR;
+		break;
+	}
+
+	if (got->offset == del->offset)
+		state |= FUSE_IEXT_LEFT_FILLING;
+	if (got_endoff == del_endoff)
+		state |= FUSE_IEXT_RIGHT_FILLING;
+
+	switch (state & (FUSE_IEXT_LEFT_FILLING | FUSE_IEXT_RIGHT_FILLING)) {
+	case FUSE_IEXT_LEFT_FILLING | FUSE_IEXT_RIGHT_FILLING:
+		/*
+		 * Matches the whole extent.  Delete the entry.
+		 */
+		fuse_iext_remove(ip, icur, state);
+		fuse_iext_prev(ifp, icur);
+		break;
+	case FUSE_IEXT_LEFT_FILLING:
+		/*
+		 * Deleting the first part of the extent.
+		 */
+		got->offset = del_endoff;
+		got->addr = del_endaddr;
+		got->length -= del->length;
+		fuse_iext_update_extent(ip, state, icur, got);
+		break;
+	case FUSE_IEXT_RIGHT_FILLING:
+		/*
+		 * Deleting the last part of the extent.
+		 */
+		got->length -= del->length;
+		fuse_iext_update_extent(ip, state, icur, got);
+		break;
+	case 0:
+		/*
+		 * Deleting the middle of the extent.
+		 */
+		got->length = del->offset - got->offset;
+		fuse_iext_update_extent(ip, state, icur, got);
+
+		new.offset = del_endoff;
+		new.length = got_endoff - del_endoff;
+		new.type = got->type;
+		new.flags = got->flags;
+		new.addr = del_endaddr;
+		new.dev = got->dev;
+
+		fuse_iext_next(ifp, icur);
+		fuse_iext_insert(ip, icur, &new, state);
+		break;
+	}
+}
+
+int
+fuse_iomap_cache_remove(
+	struct inode		*inode,
+	enum fuse_iomap_iodir	iodir,
+	loff_t			start,		/* first file offset deleted */
+	uint64_t		len)		/* length to unmap */
+{
+	struct fuse_iext_cursor	icur;
+	struct fuse_iomap_io	got;		/* current extent record */
+	struct fuse_iomap_io	del;		/* extent being deleted */
+	loff_t			end;
+	struct fuse_inode	*fi = get_fuse_inode(inode);
+	struct fuse_iomap_cache	*ip = &fi->cache;
+	struct fuse_ifork	*ifp = fuse_iomap_fork_ptr(ip, iodir);
+	bool			wasreal;
+	bool			done = false;
+	int			ret = 0;
+
+	assert_cache_locked(ip);
+
+	if (!ifp || fuse_iext_count(ifp) == 0)
+		return 0;
+
+	/* Fast shortcut if the caller wants to erase everything */
+	if (start == 0 && len >= inode->i_sb->s_maxbytes) {
+		fuse_iext_destroy(ifp);
+		return 0;
+	}
+
+	if (!len)
+		goto out;
+
+	/*
+	 * If the caller wants us to remove everything to EOF, we set the end
+	 * of the removal range to the maximum file offset.  We don't support
+	 * unsigned file offsets.
+	 */
+	if (len == FUSE_IOMAP_INVAL_TO_EOF) {
+		const unsigned int blocksize = i_blocksize(inode);
+
+		len = round_up(inode->i_sb->s_maxbytes, blocksize) - start;
+	}
+
+	/*
+	 * Now that we've settled len, look up the extent before the end of the
+	 * range.
+	 */
+	end = start + len;
+	if (!fuse_iext_lookup_extent_before(ip, ifp, &end, &icur, &got))
+		goto out;
+	end--;
+
+	while (end != -1 && end >= start) {
+		/*
+		 * Is the found extent after a hole in which end lives?
+		 * Just back up to the previous extent, if so.
+		 */
+		if (got.offset > end &&
+		    !fuse_iext_prev_extent(ifp, &icur, &got)) {
+			done = true;
+			break;
+		}
+		/*
+		 * Is the last block of this extent before the range
+		 * we're supposed to delete?  If so, we're done.
+		 */
+		end = min_t(loff_t, end, got.offset + got.length - 1);
+		if (end < start)
+			break;
+		/*
+		 * Then deal with the (possibly delayed) allocated space
+		 * we found.
+		 */
+		del = got;
+		switch (del.type) {
+		case FUSE_IOMAP_TYPE_DELALLOC:
+		case FUSE_IOMAP_TYPE_HOLE:
+		case FUSE_IOMAP_TYPE_INLINE:
+		case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
+			wasreal = false;
+			break;
+		case FUSE_IOMAP_TYPE_MAPPED:
+		case FUSE_IOMAP_TYPE_UNWRITTEN:
+			wasreal = true;
+			break;
+		default:
+			ASSERT(0);
+			ret = -EFSCORRUPTED;
+			goto out;
+		}
+
+		if (got.offset < start) {
+			del.offset = start;
+			del.length -= start - got.offset;
+			if (wasreal)
+				del.addr += start - got.offset;
+		}
+		if (del.offset + del.length > end + 1)
+			del.length = end + 1 - del.offset;
+
+		fuse_iext_del_mapping(ip, ifp, &icur, &got, &del);
+		end = del.offset - 1;
+
+		/*
+		 * If not done go on to the next (previous) record.
+		 */
+		if (end != -1 && end >= start) {
+			if (!fuse_iext_get_extent(ifp, &icur, &got) ||
+			    (got.offset > end &&
+			     !fuse_iext_prev_extent(ifp, &icur, &got))) {
+				done = true;
+				break;
+			}
+		}
+	}
+
+	/* Should have removed everything */
+	if (len == 0 || done || end == (loff_t)-1 || end < start)
+		ret = 0;
+	else
+		ret = -EFSCORRUPTED;
+
+out:
+	fuse_iext_check_mappings(inode, ip, ifp);
+	return ret;
+}
+
+static void
+fuse_iext_add_mapping(
+	struct fuse_iomap_cache		*ip,
+	struct fuse_ifork		*ifp,
+	struct fuse_iext_cursor		*icur,
+	const struct fuse_iomap_io	*new)	/* new extent entry */
+{
+	struct fuse_iomap_io		left;	/* left neighbor extent entry */
+	struct fuse_iomap_io		right;	/* right neighbor extent entry */
+	uint32_t			state = fuse_iomap_fork_to_state(ip, ifp);
+
+	/*
+	 * Check and set flags if this segment has a left neighbor.
+	 */
+	if (fuse_iext_peek_prev_extent(ifp, icur, &left))
+		state |= FUSE_IEXT_LEFT_VALID;
+
+	/*
+	 * Check and set flags if this segment has a current value.
+	 * Not true if we're inserting into the "hole" at eof.
+	 */
+	if (fuse_iext_get_extent(ifp, icur, &right))
+		state |= FUSE_IEXT_RIGHT_VALID;
+
+	/*
+	 * We're inserting a real allocation between "left" and "right".
+	 * Set the contiguity flags.  Don't let extents get too large.
+	 */
+	if ((state & FUSE_IEXT_LEFT_VALID) && fuse_iomap_can_merge(&left, new))
+		state |= FUSE_IEXT_LEFT_CONTIG;
+
+	if ((state & FUSE_IEXT_RIGHT_VALID) &&
+	    fuse_iomap_can_merge(new, &right) &&
+	    (!(state & FUSE_IEXT_LEFT_CONTIG) ||
+	     fuse_iomap_can_merge3(&left, new, &right)))
+		state |= FUSE_IEXT_RIGHT_CONTIG;
+
+	/*
+	 * Select which case we're in here, and implement it.
+	 */
+	switch (state & (FUSE_IEXT_LEFT_CONTIG | FUSE_IEXT_RIGHT_CONTIG)) {
+	case FUSE_IEXT_LEFT_CONTIG | FUSE_IEXT_RIGHT_CONTIG:
+		/*
+		 * New allocation is contiguous with real allocations on the
+		 * left and on the right.
+		 * Merge all three into a single extent record.
+		 */
+		left.length += new->length + right.length;
+
+		fuse_iext_remove(ip, icur, state);
+		fuse_iext_prev(ifp, icur);
+		fuse_iext_update_extent(ip, state, icur, &left);
+		break;
+
+	case FUSE_IEXT_LEFT_CONTIG:
+		/*
+		 * New allocation is contiguous with a real allocation
+		 * on the left.
+		 * Merge the new allocation with the left neighbor.
+		 */
+		left.length += new->length;
+
+		fuse_iext_prev(ifp, icur);
+		fuse_iext_update_extent(ip, state, icur, &left);
+		break;
+
+	case FUSE_IEXT_RIGHT_CONTIG:
+		/*
+		 * New allocation is contiguous with a real allocation
+		 * on the right.
+		 * Merge the new allocation with the right neighbor.
+		 */
+		right.offset = new->offset;
+		right.addr = new->addr;
+		right.length += new->length;
+		fuse_iext_update_extent(ip, state, icur, &right);
+		break;
+
+	case 0:
+		/*
+		 * New allocation is not contiguous with another
+		 * real allocation.
+		 * Insert a new entry.
+		 */
+		fuse_iext_insert(ip, icur, new, state);
+		break;
+	}
+}
+
+static int
+fuse_iomap_cache_add(
+	struct inode			*inode,
+	enum fuse_iomap_iodir		iodir,
+	const struct fuse_iomap_io	*new)
+{
+	struct fuse_iext_cursor		icur;
+	struct fuse_iomap_io		got;
+	struct fuse_inode		*fi = get_fuse_inode(inode);
+	struct fuse_iomap_cache		*ip = &fi->cache;
+	struct fuse_ifork		*ifp = fuse_iomap_fork_ptr(ip, iodir);
+
+	assert_cache_locked(ip);
+	ASSERT(new->length > 0);
+	ASSERT(new->offset < inode->i_sb->s_maxbytes);
+
+	if (!ifp) {
+		ifp = kzalloc(sizeof(struct fuse_ifork),
+			      GFP_KERNEL | __GFP_NOFAIL);
+		if (!ifp)
+			return -ENOMEM;
+
+		ip->im_write = ifp;
+	}
+
+	if (fuse_iext_lookup_extent(ip, ifp, new->offset, &icur, &got)) {
+		/* make sure we only add into a hole. */
+		ASSERT(got.offset > new->offset);
+		ASSERT(got.offset - new->offset >= new->length);
+
+		if (got.offset <= new->offset ||
+		    got.offset - new->offset < new->length)
+			return -EFSCORRUPTED;
+	}
+
+	fuse_iext_add_mapping(ip, ifp, &icur, new);
+	fuse_iext_check_mappings(inode, ip, ifp);
+	return 0;
+}
+
+int
+fuse_iomap_cache_upsert(
+	struct inode			*inode,
+	enum fuse_iomap_iodir		iodir,
+	const struct fuse_iomap_io	*map)
+{
+	struct fuse_inode		*fi = get_fuse_inode(inode);
+	struct fuse_iomap_cache		*ip = &fi->cache;
+	int				err;
+
+	/*
+	 * We interpret no write fork to mean that all writes are pure
+	 * overwrites.  Avoid wasting memory if we're trying to upsert a
+	 * pure overwrite.
+	 */
+	if (iodir == WRITE_MAPPING &&
+	    map->type == FUSE_IOMAP_TYPE_PURE_OVERWRITE &&
+	    ip->im_write == NULL)
+		return 0;
+
+	err = fuse_iomap_cache_remove(inode, iodir, map->offset, map->length);
+	if (err)
+		return err;
+
+	return fuse_iomap_cache_add(inode, iodir, map);
+}
+
+/*
+ * Trim the returned map to the required bounds
+ */
+static void
+fuse_iomap_trim(
+	struct fuse_inode		*fi,
+	struct fuse_iomap_lookup	*mval,
+	const struct fuse_iomap_io	*got,
+	loff_t				off,
+	loff_t				len)
+{
+	struct fuse_iomap_cache		*ip = &fi->cache;
+	const unsigned int blocksize = i_blocksize(&fi->inode);
+	const loff_t aligned_off = round_down(off, blocksize);
+	const loff_t aligned_end = round_up(off + len, blocksize);
+	const loff_t aligned_len = aligned_end - aligned_off;
+
+	ASSERT(aligned_off >= got->offset);
+
+	switch (got->type) {
+	case FUSE_IOMAP_TYPE_MAPPED:
+	case FUSE_IOMAP_TYPE_UNWRITTEN:
+		mval->map.addr = got->addr + (aligned_off - got->offset);
+		break;
+	default:
+		mval->map.addr = FUSE_IOMAP_NULL_ADDR;
+		break;
+	}
+	mval->map.offset = aligned_off;
+	mval->map.length = min_t(loff_t, aligned_len,
+				 got->length - (aligned_off - got->offset));
+	mval->map.type = got->type;
+	mval->map.flags = got->flags;
+	mval->map.dev = got->dev;
+	mval->validity_cookie = fuse_iext_read_seq(ip);
+}
+
+enum fuse_iomap_lookup_result
+fuse_iomap_cache_lookup(
+	struct inode			*inode,
+	enum fuse_iomap_iodir		iodir,
+	loff_t				off,
+	uint64_t			len,
+	struct fuse_iomap_lookup	*mval)
+{
+	struct fuse_iomap_io		got;
+	struct fuse_iext_cursor		icur;
+	struct fuse_inode		*fi = get_fuse_inode(inode);
+	struct fuse_iomap_cache		*ip = &fi->cache;
+	struct fuse_ifork		*ifp = fuse_iomap_fork_ptr(ip, iodir);
+
+	assert_cache_locked_shared(ip);
+
+	if (!ifp) {
+		/*
+		 * No write fork at all means this filesystem doesn't do out of
+		 * place writes.
+		 */
+		return LOOKUP_NOFORK;
+	}
+
+	if (!fuse_iext_lookup_extent(ip, ifp, off, &icur, &got)) {
+		/*
+		 * Write fork does not contain a mapping at or beyond off,
+		 * which is a cache miss.
+		 */
+		return LOOKUP_MISS;
+	}
+
+	if (got.offset > off) {
+		/*
+		 * Found a mapping, but it doesn't cover the start of the
+		 * range, which is effectively a miss.
+		 */
+		return LOOKUP_MISS;
+	}
+
+	/* Found a mapping in the cache, return it */
+	fuse_iomap_trim(fi, mval, &got, off, len);
+	return LOOKUP_HIT;
+}

[PATCH 02/10] fuse_trace: cache iomaps

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h  |  295 +++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/iomap_cache.c |   31 +++++
 2 files changed, 325 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 1f900580b14937..6072ef187f9215 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -315,6 +315,8 @@ DEFINE_FUSE_BACKING_EVENT(fuse_backing_close);
 struct iomap_writepage_ctx;
 struct iomap_ioend;
 struct iomap;
+struct fuse_iext_cursor;
+struct fuse_iomap_lookup;
 
 /* tracepoint boilerplate so we don't have to keep doing this */
 #define FUSE_IOMAP_OPFLAGS_FIELD \
@@ -345,6 +347,16 @@ struct iomap;
 		__entry->prefix##addr, \
 		__print_flags(__entry->prefix##flags, "|", FUSE_IOMAP_F_STRINGS)
 
+#define FUSE_IOMAP_IODIR_FIELD \
+		__field(enum fuse_iomap_iodir,	iodir)
+
+#define FUSE_IOMAP_IODIR_FMT \
+		 " iodir %s"
+
+#define FUSE_IOMAP_IODIR_PRINTK_ARGS \
+		  __print_symbolic(__entry->iodir, FUSE_IOMAP_FORK_STRINGS)
+
+
 /* combinations of boilerplate to reduce typing further */
 #define FUSE_IOMAP_OP_FIELDS(prefix) \
 		FUSE_INODE_FIELDS \
@@ -414,6 +426,7 @@ TRACE_DEFINE_ENUM(FUSE_I_BTIME);
 TRACE_DEFINE_ENUM(FUSE_I_CACHE_IO_MODE);
 TRACE_DEFINE_ENUM(FUSE_I_IOMAP);
 TRACE_DEFINE_ENUM(FUSE_I_ATOMIC);
+TRACE_DEFINE_ENUM(FUSE_I_IOMAP_CACHE);
 
 #define FUSE_IFLAG_STRINGS \
 	{ 1 << FUSE_I_ADVISE_RDPLUS,		"advise_rdplus" }, \
@@ -423,7 +436,8 @@ TRACE_DEFINE_ENUM(FUSE_I_ATOMIC);
 	{ 1 << FUSE_I_BTIME,			"btime" }, \
 	{ 1 << FUSE_I_CACHE_IO_MODE,		"cacheio" }, \
 	{ 1 << FUSE_I_IOMAP,			"iomap" }, \
-	{ 1 << FUSE_I_ATOMIC,			"atomic" }
+	{ 1 << FUSE_I_ATOMIC,			"atomic" }, \
+	{ 1 << FUSE_I_IOMAP_CACHE,		"iomap_cache" }
 
 #define IOMAP_IOEND_STRINGS \
 	{ IOMAP_IOEND_SHARED,			"shared" }, \
@@ -439,6 +453,22 @@ TRACE_DEFINE_ENUM(FUSE_I_ATOMIC);
 	{ FUSE_IOMAP_CONFIG_TIME,		"time" }, \
 	{ FUSE_IOMAP_CONFIG_MAXBYTES,		"maxbytes" }
 
+TRACE_DEFINE_ENUM(READ_MAPPING);
+TRACE_DEFINE_ENUM(WRITE_MAPPING);
+
+#define FUSE_IOMAP_FORK_STRINGS \
+	{ READ_MAPPING,				"read" }, \
+	{ WRITE_MAPPING,			"write" }
+
+#define FUSE_IEXT_STATE_STRINGS \
+	{ FUSE_IEXT_LEFT_CONTIG,		"l_cont" }, \
+	{ FUSE_IEXT_RIGHT_CONTIG,		"r_cont" }, \
+	{ FUSE_IEXT_LEFT_FILLING,		"l_fill" }, \
+	{ FUSE_IEXT_RIGHT_FILLING,		"r_fill" }, \
+	{ FUSE_IEXT_LEFT_VALID,			"l_valid" }, \
+	{ FUSE_IEXT_RIGHT_VALID,		"r_valid" }, \
+	{ FUSE_IEXT_WRITE_MAPPING,		"write" }
+
 DECLARE_EVENT_CLASS(fuse_iomap_check_class,
 	TP_PROTO(const char *func, int line, const char *condition),
 
@@ -1178,6 +1208,269 @@ DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_inline_read);
 DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_inline_write);
 DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_set_inline_iomap);
 DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_set_inline_srcmap);
+
+DECLARE_EVENT_CLASS(fuse_iext_class,
+	TP_PROTO(const struct inode *inode, const struct fuse_iext_cursor *cur,
+		 int state, unsigned long caller_ip),
+
+	TP_ARGS(inode, cur, state, caller_ip),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		FUSE_IOMAP_MAP_FIELDS(map)
+		__field(void *,			leaf)
+		__field(int,			pos)
+		__field(int,			iext_state)
+		__field(unsigned long,		caller_ip)
+	),
+	TP_fast_assign(
+		const struct fuse_ifork *ifp;
+		struct fuse_iomap_io r = { };
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+
+		if (state & FUSE_IEXT_WRITE_MAPPING)
+			ifp = fi->cache.im_write;
+		else
+			ifp = &fi->cache.im_read;
+		if (ifp)
+			fuse_iext_get_extent(ifp, cur, &r);
+
+		__entry->mapoffset	=	r.offset;
+		__entry->mapaddr	=	r.addr;
+		__entry->maplength	=	r.length;
+		__entry->mapdev		=	r.dev;
+		__entry->maptype	=	r.type;
+		__entry->mapflags	=	r.flags;
+
+		__entry->leaf		=	cur->leaf;
+		__entry->pos		=	cur->pos;
+
+		__entry->iext_state	=	state;
+		__entry->caller_ip	=	caller_ip;
+	),
+	TP_printk(FUSE_INODE_FMT " state (%s) cur %p/%d " FUSE_IOMAP_MAP_FMT() " caller %pS",
+		  FUSE_INODE_PRINTK_ARGS,
+		  __print_flags(__entry->iext_state, "|", FUSE_IEXT_STATE_STRINGS),
+		  __entry->leaf,
+		  __entry->pos,
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map),
+		  (void *)__entry->caller_ip)
+)
+
+#define DEFINE_IEXT_EVENT(name) \
+DEFINE_EVENT(fuse_iext_class, name, \
+	TP_PROTO(const struct inode *inode, const struct fuse_iext_cursor *cur, \
+		 int state, unsigned long caller_ip), \
+	TP_ARGS(inode, cur, state, caller_ip))
+DEFINE_IEXT_EVENT(fuse_iext_insert);
+DEFINE_IEXT_EVENT(fuse_iext_remove);
+DEFINE_IEXT_EVENT(fuse_iext_pre_update);
+DEFINE_IEXT_EVENT(fuse_iext_post_update);
+
+TRACE_EVENT(fuse_iext_update_class,
+	TP_PROTO(const struct inode *inode, uint32_t iext_state,
+		 const struct fuse_iomap_io *map),
+	TP_ARGS(inode, iext_state, map),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		FUSE_IOMAP_MAP_FIELDS(map)
+		__field(uint32_t,		iext_state)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->mapoffset	=	map->offset;
+		__entry->maplength	=	map->length;
+		__entry->maptype	=	map->type;
+		__entry->mapflags	=	map->flags;
+		__entry->mapdev		=	map->dev;
+		__entry->mapaddr	=	map->addr;
+
+		__entry->iext_state	=	iext_state;
+	),
+
+	TP_printk(FUSE_INODE_FMT " state (%s)" FUSE_IOMAP_MAP_FMT(),
+		  FUSE_INODE_PRINTK_ARGS,
+		  __print_flags(__entry->iext_state, "|", FUSE_IEXT_STATE_STRINGS),
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map))
+);
+#define DEFINE_IEXT_UPDATE_EVENT(name) \
+DEFINE_EVENT(fuse_iext_update_class, name, \
+	TP_PROTO(const struct inode *inode, uint32_t iext_state, \
+		 const struct fuse_iomap_io *map), \
+	TP_ARGS(inode, iext_state, map))
+DEFINE_IEXT_UPDATE_EVENT(fuse_iext_del_mapping);
+DEFINE_IEXT_UPDATE_EVENT(fuse_iext_add_mapping);
+
+TRACE_EVENT(fuse_iext_alt_update_class,
+	TP_PROTO(const struct inode *inode, const struct fuse_iomap_io *map),
+	TP_ARGS(inode, map),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		FUSE_IOMAP_MAP_FIELDS(map)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+
+		__entry->mapoffset	=	map->offset;
+		__entry->maplength	=	map->length;
+		__entry->maptype	=	map->type;
+		__entry->mapflags	=	map->flags;
+		__entry->mapdev		=	map->dev;
+		__entry->mapaddr	=	map->addr;
+	),
+
+	TP_printk(FUSE_INODE_FMT FUSE_IOMAP_MAP_FMT(),
+		  FUSE_INODE_PRINTK_ARGS,
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map))
+);
+#define DEFINE_IEXT_ALT_UPDATE_EVENT(name) \
+DEFINE_EVENT(fuse_iext_alt_update_class, name, \
+	TP_PROTO(const struct inode *inode, const struct fuse_iomap_io *map), \
+	TP_ARGS(inode, map))
+DEFINE_IEXT_ALT_UPDATE_EVENT(fuse_iext_del_mapping_got);
+DEFINE_IEXT_ALT_UPDATE_EVENT(fuse_iext_add_mapping_left);
+DEFINE_IEXT_ALT_UPDATE_EVENT(fuse_iext_add_mapping_right);
+
+TRACE_EVENT(fuse_iomap_cache_remove,
+	TP_PROTO(const struct inode *inode, enum fuse_iomap_iodir iodir,
+		 loff_t offset, uint64_t length, unsigned long caller_ip),
+	TP_ARGS(inode, iodir, offset, length, caller_ip),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		FUSE_IOMAP_IODIR_FIELD
+		__field(unsigned long,		caller_ip)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->iodir		=	iodir;
+		__entry->offset		=	offset;
+		__entry->length		=	length;
+		__entry->caller_ip	=	caller_ip;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() FUSE_IOMAP_IODIR_FMT " caller %pS",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  FUSE_IOMAP_IODIR_PRINTK_ARGS,
+		  (void *)__entry->caller_ip)
+);
+
+TRACE_EVENT(fuse_iomap_cached_mapping_class,
+	TP_PROTO(const struct inode *inode, enum fuse_iomap_iodir iodir,
+		 const struct fuse_iomap_io *map, unsigned long caller_ip),
+	TP_ARGS(inode, iodir, map, caller_ip),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		FUSE_IOMAP_IODIR_FIELD
+		FUSE_IOMAP_MAP_FIELDS(map)
+		__field(unsigned long,		caller_ip)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->iodir		=	iodir;
+
+		__entry->mapoffset	=	map->offset;
+		__entry->maplength	=	map->length;
+		__entry->maptype	=	map->type;
+		__entry->mapflags	=	map->flags;
+		__entry->mapdev		=	map->dev;
+		__entry->mapaddr	=	map->addr;
+
+		__entry->caller_ip	=	caller_ip;
+	),
+
+	TP_printk(FUSE_INODE_FMT FUSE_IOMAP_IODIR_FMT FUSE_IOMAP_MAP_FMT() " caller %pS",
+		  FUSE_INODE_PRINTK_ARGS,
+		  FUSE_IOMAP_IODIR_PRINTK_ARGS,
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map),
+		  (void *)__entry->caller_ip)
+);
+#define DEFINE_FUSE_IOMAP_CACHED_MAPPING_EVENT(name) \
+DEFINE_EVENT(fuse_iomap_cached_mapping_class, name, \
+	TP_PROTO(const struct inode *inode, enum fuse_iomap_iodir iodir, \
+		 const struct fuse_iomap_io *map, unsigned long caller_ip), \
+	TP_ARGS(inode, iodir, map, caller_ip))
+DEFINE_FUSE_IOMAP_CACHED_MAPPING_EVENT(fuse_iomap_cache_add);
+DEFINE_FUSE_IOMAP_CACHED_MAPPING_EVENT(fuse_iext_check_mapping);
+
+TRACE_EVENT(fuse_iomap_cache_lookup,
+	TP_PROTO(const struct inode *inode, enum fuse_iomap_iodir iodir,
+		 loff_t pos, uint64_t count, unsigned long caller_ip),
+	TP_ARGS(inode, iodir, pos, count, caller_ip),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+		FUSE_IOMAP_IODIR_FIELD
+		__field(unsigned long,		caller_ip)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->iodir		=	iodir;
+		__entry->offset		=	pos;
+		__entry->length		=	count;
+		__entry->caller_ip	=	caller_ip;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() FUSE_IOMAP_IODIR_FMT " caller %pS",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  FUSE_IOMAP_IODIR_PRINTK_ARGS,
+		  (void *)__entry->caller_ip)
+);
+
+TRACE_EVENT(fuse_iomap_cache_lookup_result,
+	TP_PROTO(const struct inode *inode, enum fuse_iomap_iodir iodir,
+		 loff_t pos, uint64_t count, const struct fuse_iomap_io *got,
+		 const struct fuse_iomap_lookup *map),
+	TP_ARGS(inode, iodir, pos, count, got, map),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+
+		FUSE_IOMAP_MAP_FIELDS(got)
+		FUSE_IOMAP_MAP_FIELDS(map)
+
+		FUSE_IOMAP_IODIR_FIELD
+		__field(uint64_t,		validity_cookie)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->iodir		=	iodir;
+		__entry->offset		=	pos;
+		__entry->length		=	count;
+
+		__entry->gotoffset	=	got->offset;
+		__entry->gotlength	=	got->length;
+		__entry->gottype	=	got->type;
+		__entry->gotflags	=	got->flags;
+		__entry->gotdev		=	got->dev;
+		__entry->gotaddr	=	got->addr;
+
+		__entry->mapoffset	=	map->map.offset;
+		__entry->maplength	=	map->map.length;
+		__entry->maptype	=	map->map.type;
+		__entry->mapflags	=	map->map.flags;
+		__entry->mapdev		=	map->map.dev;
+		__entry->mapaddr	=	map->map.addr;
+
+		__entry->validity_cookie=	map->validity_cookie;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT() FUSE_IOMAP_IODIR_FMT FUSE_IOMAP_MAP_FMT("map") FUSE_IOMAP_MAP_FMT("got") " cookie 0x%llx",
+		  FUSE_IO_RANGE_PRINTK_ARGS(),
+		  FUSE_IOMAP_IODIR_PRINTK_ARGS,
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map),
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(got),
+		  __entry->validity_cookie)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/iomap_cache.c b/fs/fuse/iomap_cache.c
index 1fec9dcc6d3922..5bfa0e26346d1f 100644
--- a/fs/fuse/iomap_cache.c
+++ b/fs/fuse/iomap_cache.c
@@ -717,6 +717,7 @@ fuse_iext_insert(
 	struct fuse_ifork		*ifp = fuse_iext_state_to_fork(ip, state);
 
 	fuse_iext_insert_raw(ip, ifp, cur, irec);
+	trace_fuse_iext_insert(VFS_I(ip), cur, state, _RET_IP_);
 }
 
 static struct fuse_iext_node *
@@ -920,6 +921,8 @@ fuse_iext_remove(
 	loff_t			offset = fuse_iext_leaf_key(leaf, 0);
 	int			i, nr_entries;
 
+	trace_fuse_iext_remove(VFS_I(ip), cur, state, _RET_IP_);
+
 	ASSERT(ifp->if_height > 0);
 	ASSERT(ifp->if_data != NULL);
 	ASSERT(fuse_iext_valid(ifp, cur));
@@ -1042,7 +1045,9 @@ fuse_iext_update_extent(
 		}
 	}
 
+	trace_fuse_iext_pre_update(VFS_I(ip), cur, state, _RET_IP_);
 	fuse_iext_set(cur_rec(cur), new);
+	trace_fuse_iext_post_update(VFS_I(ip), cur, state, _RET_IP_);
 }
 
 /*
@@ -1150,17 +1155,25 @@ static void fuse_iext_check_mappings(struct inode *inode,
 	struct fuse_iext_cursor	icur;
 	struct fuse_iomap_io	prev, got;
 	unsigned long long	nr = 0;
+	enum fuse_iomap_iodir	iodir;
 
 	if (!ifp || !static_branch_unlikely(&fuse_iomap_debug))
 		return;
 
+	if (ifp == ip->im_write)
+		iodir = WRITE_MAPPING;
+	else
+		iodir = READ_MAPPING;
+
 	fuse_iext_first(ifp, &icur);
 	if (!fuse_iext_get_extent(ifp, &icur, &prev))
 		return;
+	trace_fuse_iext_check_mapping(inode, iodir, &prev, _RET_IP_);
 	nr++;
 
 	fuse_iext_next(ifp, &icur);
 	while (fuse_iext_get_extent(ifp, &icur, &got)) {
+		trace_fuse_iext_check_mapping(inode, iodir, &got, _RET_IP_);
 		if (got.length == 0 ||
 		    got.offset < prev.offset + prev.length ||
 		    fuse_iomap_can_merge(&prev, &got)) {
@@ -1219,6 +1232,9 @@ fuse_iext_del_mapping(
 	if (got_endoff == del_endoff)
 		state |= FUSE_IEXT_RIGHT_FILLING;
 
+	trace_fuse_iext_del_mapping(VFS_I(ip), state, del);
+	trace_fuse_iext_del_mapping_got(VFS_I(ip), got);
+
 	switch (state & (FUSE_IEXT_LEFT_FILLING | FUSE_IEXT_RIGHT_FILLING)) {
 	case FUSE_IEXT_LEFT_FILLING | FUSE_IEXT_RIGHT_FILLING:
 		/*
@@ -1283,6 +1299,8 @@ fuse_iomap_cache_remove(
 
 	assert_cache_locked(ip);
 
+	trace_fuse_iomap_cache_remove(inode, iodir, start, len, _RET_IP_);
+
 	if (!ifp || fuse_iext_count(ifp) == 0)
 		return 0;
 
@@ -1427,6 +1445,12 @@ fuse_iext_add_mapping(
 	     fuse_iomap_can_merge3(&left, new, &right)))
 		state |= FUSE_IEXT_RIGHT_CONTIG;
 
+	trace_fuse_iext_add_mapping(VFS_I(ip), state, new);
+	if (state & FUSE_IEXT_LEFT_VALID)
+		trace_fuse_iext_add_mapping_left(VFS_I(ip), &left);
+	if (state & FUSE_IEXT_RIGHT_VALID)
+		trace_fuse_iext_add_mapping_right(VFS_I(ip), &right);
+
 	/*
 	 * Select which case we're in here, and implement it.
 	 */
@@ -1495,6 +1519,8 @@ fuse_iomap_cache_add(
 	ASSERT(new->length > 0);
 	ASSERT(new->offset < inode->i_sb->s_maxbytes);
 
+	trace_fuse_iomap_cache_add(inode, iodir, new, _RET_IP_);
+
 	if (!ifp) {
 		ifp = kzalloc(sizeof(struct fuse_ifork),
 			      GFP_KERNEL | __GFP_NOFAIL);
@@ -1599,6 +1625,8 @@ fuse_iomap_cache_lookup(
 
 	assert_cache_locked_shared(ip);
 
+	trace_fuse_iomap_cache_lookup(inode, iodir, off, len, _RET_IP_);
+
 	if (!ifp) {
 		/*
 		 * No write fork at all means this filesystem doesn't do out of
@@ -1625,5 +1653,8 @@ fuse_iomap_cache_lookup(
 
 	/* Found a mapping in the cache, return it */
 	fuse_iomap_trim(fi, mval, &got, off, len);
+
+	trace_fuse_iomap_cache_lookup_result(inode, iodir, off, len, &got,
+					     mval);
 	return LOOKUP_HIT;
 }

[PATCH 03/10] fuse: use the iomap cache for iomap_begin

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Look inside the iomap cache to try to satisfy iomap_begin.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/iomap_priv.h  |    5 +
 fs/fuse/file_iomap.c  |  216 ++++++++++++++++++++++++++++++++++++++++++++++++-
 fs/fuse/iomap_cache.c |    6 +
 3 files changed, 221 insertions(+), 6 deletions(-)


diff --git a/fs/fuse/iomap_priv.h b/fs/fuse/iomap_priv.h
index 8e4a32879025a4..8f1aef381942b6 100644
--- a/fs/fuse/iomap_priv.h
+++ b/fs/fuse/iomap_priv.h
@@ -145,6 +145,11 @@ static inline bool fuse_iext_peek_prev_extent(struct fuse_ifork *ifp,
 	     fuse_iext_get_extent((ifp), (ext), (got));	\
 	     fuse_iext_next((ifp), (ext)))
 
+/* iomaps that come direct from the fuse server are presumed to be valid */
+#define FUSE_IOMAP_ALWAYS_VALID	((uint64_t)0)
+/* set initial iomap cookie value to avoid ALWAYS_VALID */
+#define FUSE_IOMAP_INIT_COOKIE	((uint64_t)1)
+
 static inline uint64_t fuse_iext_read_seq(struct fuse_iomap_cache *ip)
 {
 	return (uint64_t)READ_ONCE(ip->im_seq);
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index d35e69d03b0940..47c82ec29238e3 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -165,6 +165,7 @@ static inline bool fuse_iomap_check_type(uint16_t fuse_type)
 	case FUSE_IOMAP_TYPE_UNWRITTEN:
 	case FUSE_IOMAP_TYPE_INLINE:
 	case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
+	case FUSE_IOMAP_TYPE_RETRY_CACHE:
 		return true;
 	}
 
@@ -270,9 +271,14 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
 	const unsigned int blocksize = i_blocksize(inode);
 	uint64_t end;
 
-	/* Type and flags must be known */
+	/*
+	 * Type and flags must be known.  Mapping type "retry cache" doesn't
+	 * use any of the other fields.
+	 */
 	if (BAD_DATA(!fuse_iomap_check_type(map->type)))
 		return false;
+	if (map->type == FUSE_IOMAP_TYPE_RETRY_CACHE)
+		return true;
 	if (BAD_DATA(!fuse_iomap_check_flags(map->flags)))
 		return false;
 
@@ -303,6 +309,14 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
 		if (BAD_DATA(map->addr == FUSE_IOMAP_NULL_ADDR))
 			return false;
 		break;
+	case FUSE_IOMAP_TYPE_RETRY_CACHE:
+		/*
+		 * We only accept cache retries if we have a cache to query.
+		 * There must not be a device addr.
+		 */
+		if (BAD_DATA(!fuse_inode_caches_iomaps(inode)))
+			return false;
+		fallthrough;
 	case FUSE_IOMAP_TYPE_DELALLOC:
 	case FUSE_IOMAP_TYPE_HOLE:
 	case FUSE_IOMAP_TYPE_INLINE:
@@ -568,6 +582,149 @@ static int fuse_iomap_set_inline(struct inode *inode, unsigned opflags,
 	return 0;
 }
 
+/* Convert a mapping from the cache into something the kernel can use */
+static int fuse_iomap_from_cache(struct inode *inode, struct iomap *iomap,
+				 const struct fuse_iomap_lookup *lmap)
+{
+	struct fuse_mount *fm = get_fuse_mount(inode);
+	struct fuse_backing *fb;
+
+	fb = fuse_iomap_find_dev(fm->fc, &lmap->map);
+	if (IS_ERR(fb))
+		return PTR_ERR(fb);
+
+	fuse_iomap_from_server(inode, iomap, fb, &lmap->map);
+	iomap->validity_cookie = lmap->validity_cookie;
+
+	fuse_backing_put(fb);
+	return 0;
+}
+
+#if IS_ENABLED(CONFIG_FUSE_IOMAP_DEBUG)
+static inline int
+fuse_iomap_cached_validate(const struct inode *inode,
+			   enum fuse_iomap_iodir dir,
+			   const struct fuse_iomap_lookup *lmap)
+{
+	if (!static_branch_unlikely(&fuse_iomap_debug))
+		return 0;
+
+	/* Make sure the mappings aren't garbage */
+	if (!fuse_iomap_check_mapping(inode, &lmap->map, dir))
+		return -EFSCORRUPTED;
+
+	/* The cache should not be storing "retry cache" mappings */
+	if (BAD_DATA(lmap->map.type == FUSE_IOMAP_TYPE_RETRY_CACHE))
+		return -EFSCORRUPTED;
+
+	return 0;
+}
+#else
+# define fuse_iomap_cached_validate(...)	(0)
+#endif
+
+/*
+ * Look up iomappings from the cache.  Returns 1 if iomap and srcmap were
+ * satisfied from cache; 0 if not; or a negative errno.
+ */
+static int fuse_iomap_try_cache(struct inode *inode, loff_t pos, loff_t count,
+				unsigned opflags, struct iomap *iomap,
+				struct iomap *srcmap)
+{
+	struct fuse_iomap_lookup lmap;
+	struct iomap *dest = iomap;
+	enum fuse_iomap_lookup_result res;
+	int ret;
+
+	if (!fuse_inode_caches_iomaps(inode))
+		return 0;
+
+	fuse_iomap_cache_lock_shared(inode);
+
+	if (fuse_is_iomap_file_write(opflags)) {
+		res = fuse_iomap_cache_lookup(inode, WRITE_MAPPING, pos, count,
+					      &lmap);
+		switch (res) {
+		case LOOKUP_HIT:
+			ret = fuse_iomap_cached_validate(inode, WRITE_MAPPING,
+					&lmap);
+			if (ret)
+				goto out_unlock;
+
+			if (lmap.map.type != FUSE_IOMAP_TYPE_PURE_OVERWRITE) {
+				ret = fuse_iomap_from_cache(inode, dest, &lmap);
+				if (ret)
+					goto out_unlock;
+
+				dest = srcmap;
+			}
+			fallthrough;
+		case LOOKUP_NOFORK:
+			/* move on to the read fork */
+			break;
+		case LOOKUP_MISS:
+			ret = 0;
+			goto out_unlock;
+		}
+	}
+
+	res = fuse_iomap_cache_lookup(inode, READ_MAPPING, pos, count, &lmap);
+	switch (res) {
+	case LOOKUP_HIT:
+		break;
+	case LOOKUP_NOFORK:
+		ASSERT(res != LOOKUP_NOFORK);
+		ret = -EFSCORRUPTED;
+		goto out_unlock;
+	case LOOKUP_MISS:
+		ret = 0;
+		goto out_unlock;
+	}
+
+	ret = fuse_iomap_cached_validate(inode, READ_MAPPING, &lmap);
+	if (ret)
+		goto out_unlock;
+
+	ret = fuse_iomap_from_cache(inode, dest, &lmap);
+	if (ret)
+		goto out_unlock;
+
+	if (fuse_is_iomap_file_write(opflags)) {
+		switch (iomap->type) {
+		case IOMAP_HOLE:
+			if (opflags & (IOMAP_ZERO | IOMAP_UNSHARE))
+				ret = 1;
+			else
+				ret = 0;
+			break;
+		case IOMAP_DELALLOC:
+			if (opflags & IOMAP_DIRECT)
+				ret = 0;
+			else
+				ret = 1;
+			break;
+		default:
+			ret = 1;
+			break;
+		}
+	} else {
+		ret = 1;
+	}
+
+out_unlock:
+	fuse_iomap_cache_unlock_shared(inode);
+	if (ret < 1)
+		return ret;
+
+	if (iomap->type == IOMAP_INLINE || srcmap->type == IOMAP_INLINE) {
+		ret = fuse_iomap_set_inline(inode, opflags, pos, count, iomap,
+					    srcmap);
+		if (ret)
+			return ret;
+	}
+	return 1;
+}
+
 static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 			    unsigned opflags, struct iomap *iomap,
 			    struct iomap *srcmap)
@@ -588,6 +745,21 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 
 	trace_fuse_iomap_begin(inode, pos, count, opflags);
 
+	/*
+	 * Try to read mappings from the cache; if we find something then use
+	 * it; otherwise we upcall the fuse server.  For atomic writes we must
+	 * always query the server.
+	 */
+	if (!(opflags & FUSE_IOMAP_OP_ATOMIC)) {
+		err = fuse_iomap_try_cache(inode, pos, count, opflags, iomap,
+					   srcmap);
+		if (err < 0)
+			return err;
+		if (err == 1)
+			return 0;
+	}
+
+retry:
 	args.opcode = FUSE_IOMAP_BEGIN;
 	args.nodeid = get_node_id(inode);
 	args.in_numargs = 1;
@@ -609,6 +781,24 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 	if (err)
 		return err;
 
+	/*
+	 * If the fuse server tells us it populated the cache, we'll try the
+	 * cache lookup again.  Note that we dropped the cache lock, so it's
+	 * entirely possible that another thread could have invalidated the
+	 * cache -- if the cache misses, we'll call the server again.
+	 */
+	if (outarg.read.type == FUSE_IOMAP_TYPE_RETRY_CACHE) {
+		err = fuse_iomap_try_cache(inode, pos, count, opflags, iomap,
+					   srcmap);
+		if (err < 0)
+			return err;
+		if (err == 1)
+			return 0;
+		if (signal_pending(current))
+			return -EINTR;
+		goto retry;
+	}
+
 	read_dev = fuse_iomap_find_dev(fm->fc, &outarg.read);
 	if (IS_ERR(read_dev))
 		return PTR_ERR(read_dev);
@@ -636,6 +826,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
 		 */
 		fuse_iomap_from_server(inode, iomap, read_dev, &outarg.read);
 	}
+	iomap->validity_cookie = FUSE_IOMAP_ALWAYS_VALID;
+	srcmap->validity_cookie = FUSE_IOMAP_ALWAYS_VALID;
 
 	if (iomap->type == IOMAP_INLINE || srcmap->type == IOMAP_INLINE) {
 		err = fuse_iomap_set_inline(inode, opflags, pos, count, iomap,
@@ -1338,7 +1530,21 @@ static const struct iomap_dio_ops fuse_iomap_dio_write_ops = {
 	.end_io		= fuse_iomap_dio_write_end_io,
 };
 
+static bool fuse_iomap_revalidate(struct inode *inode,
+				  const struct iomap *iomap)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	uint64_t validity_cookie;
+
+	if (iomap->validity_cookie == FUSE_IOMAP_ALWAYS_VALID)
+		return true;
+
+	validity_cookie = fuse_iext_read_seq(&fi->cache);
+	return iomap->validity_cookie == validity_cookie;
+}
+
 static const struct iomap_write_ops fuse_iomap_write_ops = {
+	.iomap_valid		= fuse_iomap_revalidate,
 };
 
 static int
@@ -1606,14 +1812,14 @@ static void fuse_iomap_end_bio(struct bio *bio)
  * mapping is valid, false otherwise.
  */
 static bool fuse_iomap_revalidate_writeback(struct iomap_writepage_ctx *wpc,
+					    struct inode *inode,
 					    loff_t offset)
 {
 	if (offset < wpc->iomap.offset ||
 	    offset >= wpc->iomap.offset + wpc->iomap.length)
 		return false;
 
-	/* XXX actually use revalidation cookie */
-	return true;
+	return fuse_iomap_revalidate(inode, &wpc->iomap);
 }
 
 /*
@@ -1667,7 +1873,7 @@ static ssize_t fuse_iomap_writeback_range(struct iomap_writepage_ctx *wpc,
 
 	trace_fuse_iomap_writeback_range(inode, offset, len, end_pos);
 
-	if (!fuse_iomap_revalidate_writeback(wpc, offset)) {
+	if (!fuse_iomap_revalidate_writeback(wpc, inode, offset)) {
 		ret = fuse_iomap_begin(inode, offset, len,
 				       FUSE_IOMAP_OP_WRITEBACK,
 				       &write_iomap, &dontcare);
@@ -1804,7 +2010,7 @@ static inline void fuse_inode_set_iomap(struct inode *inode)
 	mapping_set_folio_min_order(inode->i_mapping, min_order);
 
 	memset(&fi->cache.im_read, 0, sizeof(fi->cache.im_read));
-	fi->cache.im_seq = 0;
+	fi->cache.im_seq = FUSE_IOMAP_INIT_COOKIE;
 	fi->cache.im_write = NULL;
 
 	init_rwsem(&fi->cache.im_lock);
diff --git a/fs/fuse/iomap_cache.c b/fs/fuse/iomap_cache.c
index 5bfa0e26346d1f..572bccf99a97a8 100644
--- a/fs/fuse/iomap_cache.c
+++ b/fs/fuse/iomap_cache.c
@@ -660,7 +660,11 @@ fuse_iext_realloc_root(
  */
 static inline void fuse_iext_inc_seq(struct fuse_iomap_cache *ip)
 {
-	WRITE_ONCE(ip->im_seq, READ_ONCE(ip->im_seq) + 1);
+	uint64_t new_val = READ_ONCE(ip->im_seq) + 1;
+
+	if (new_val == FUSE_IOMAP_ALWAYS_VALID)
+		new_val++;
+	WRITE_ONCE(ip->im_seq, new_val);
 }
 
 void

[PATCH 04/10] fuse_trace: use the iomap cache for iomap_begin

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   34 ++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |    7 ++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 6072ef187f9215..5f399b1604a2ac 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -400,6 +400,7 @@ struct fuse_iomap_lookup;
 
 #define FUSE_IOMAP_TYPE_STRINGS \
 	{ FUSE_IOMAP_TYPE_PURE_OVERWRITE,	"overwrite" }, \
+	{ FUSE_IOMAP_TYPE_RETRY_CACHE,		"retry" }, \
 	{ FUSE_IOMAP_TYPE_HOLE,			"hole" }, \
 	{ FUSE_IOMAP_TYPE_DELALLOC,		"delalloc" }, \
 	{ FUSE_IOMAP_TYPE_MAPPED,		"mapped" }, \
@@ -1471,6 +1472,39 @@ TRACE_EVENT(fuse_iomap_cache_lookup_result,
 		  FUSE_IOMAP_MAP_PRINTK_ARGS(got),
 		  __entry->validity_cookie)
 );
+
+TRACE_EVENT(fuse_iomap_invalid,
+	TP_PROTO(const struct inode *inode, const struct iomap *map,
+		 uint64_t validity_cookie),
+	TP_ARGS(inode, map, validity_cookie),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		FUSE_IOMAP_MAP_FIELDS(map)
+		__field(uint64_t,		old_validity_cookie)
+		__field(uint64_t,		validity_cookie)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+
+		__entry->mapoffset	=	map->offset;
+		__entry->maplength	=	map->length;
+		__entry->maptype	=	map->type;
+		__entry->mapflags	=	map->flags;
+		__entry->mapaddr	=	map->addr;
+		__entry->mapdev		=	FUSE_IOMAP_DEV_NULL;
+
+		__entry->old_validity_cookie=	map->validity_cookie;
+		__entry->validity_cookie=	validity_cookie;
+	),
+
+	TP_printk(FUSE_INODE_FMT FUSE_IOMAP_MAP_FMT() " old_cookie 0x%llx new_cookie 0x%llx",
+		  FUSE_INODE_PRINTK_ARGS,
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(map),
+		  __entry->old_validity_cookie,
+		  __entry->validity_cookie)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 47c82ec29238e3..b568a862f120ff 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -1540,7 +1540,12 @@ static bool fuse_iomap_revalidate(struct inode *inode,
 		return true;
 
 	validity_cookie = fuse_iext_read_seq(&fi->cache);
-	return iomap->validity_cookie == validity_cookie;
+	if (unlikely(iomap->validity_cookie != validity_cookie)) {
+		trace_fuse_iomap_invalid(inode, iomap, validity_cookie);
+		return false;
+	}
+
+	return true;
 }
 
 static const struct iomap_write_ops fuse_iomap_write_ops = {

[PATCH 05/10] fuse: invalidate iomap cache after file updates

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

The kernel doesn't know what the fuse server might have done in response
to truncate, fallocate, or ioend events.  Therefore, it must invalidate
the mapping cache after those operations to ensure cache coherency.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h      |    7 +++++++
 fs/fuse/iomap_priv.h  |    9 +++++++++
 fs/fuse/dir.c         |    6 ++++++
 fs/fuse/file.c        |   10 +++++++---
 fs/fuse/file_iomap.c  |   42 +++++++++++++++++++++++++++++++++++++++++-
 fs/fuse/iomap_cache.c |   27 +++++++++++++++++++++++++++
 6 files changed, 97 insertions(+), 4 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 33b65253b2e9be..c6ec9383a99ce5 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1831,10 +1831,14 @@ int fuse_iomap_mmap(struct file *file, struct vm_area_struct *vma);
 ssize_t fuse_iomap_buffered_read(struct kiocb *iocb, struct iov_iter *to);
 ssize_t fuse_iomap_buffered_write(struct kiocb *iocb, struct iov_iter *from);
 int fuse_iomap_setsize_start(struct inode *inode, loff_t newsize);
+int fuse_iomap_setsize_finish(struct inode *inode, loff_t newsize);
 int fuse_iomap_fallocate(struct file *file, int mode, loff_t offset,
 			 loff_t length, loff_t new_size);
 int fuse_iomap_flush_unmap_range(struct inode *inode, loff_t pos,
 				 loff_t endpos);
+void fuse_iomap_open_truncate(struct inode *inode);
+void fuse_iomap_copied_file_range(struct inode *inode, loff_t offset,
+				  size_t written);
 
 int fuse_dev_ioctl_iomap_support(struct file *file,
 				 struct fuse_iomap_support __user *argp);
@@ -1875,8 +1879,11 @@ enum fuse_iomap_iodir {
 # define fuse_iomap_buffered_read(...)		(-ENOSYS)
 # define fuse_iomap_buffered_write(...)		(-ENOSYS)
 # define fuse_iomap_setsize_start(...)		(-ENOSYS)
+# define fuse_iomap_setsize_finish(...)		(-ENOSYS)
 # define fuse_iomap_fallocate(...)		(-ENOSYS)
 # define fuse_iomap_flush_unmap_range(...)	(-ENOSYS)
+# define fuse_iomap_open_truncate(...)		((void)0)
+# define fuse_iomap_copied_file_range(...)	((void)0)
 # define fuse_dev_ioctl_iomap_support(...)	(-EOPNOTSUPP)
 # define fuse_iomap_dev_inval(...)		(-ENOSYS)
 # define fuse_iomap_fadvise			NULL
diff --git a/fs/fuse/iomap_priv.h b/fs/fuse/iomap_priv.h
index 8f1aef381942b6..e78c49af638e0f 100644
--- a/fs/fuse/iomap_priv.h
+++ b/fs/fuse/iomap_priv.h
@@ -177,6 +177,15 @@ fuse_iomap_cache_lookup(struct inode *inode, enum fuse_iomap_iodir iodir,
 			loff_t off, uint64_t len,
 			struct fuse_iomap_lookup *mval);
 
+int fuse_iomap_cache_invalidate_range(struct inode *inode, loff_t offset,
+				      uint64_t length);
+static inline int fuse_iomap_cache_invalidate(struct inode *inode,
+					      loff_t offset)
+{
+	return fuse_iomap_cache_invalidate_range(inode, offset,
+						 FUSE_IOMAP_INVAL_TO_EOF);
+}
+
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _FS_FUSE_IOMAP_PRIV_H */
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 9adaf262bda975..c7291d968ba89c 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -2208,6 +2208,12 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		goto error;
 	}
 
+	if (is_iomap && is_truncate) {
+		err = fuse_iomap_setsize_finish(inode, outarg.attr.size);
+		if (err)
+			goto error;
+	}
+
 	spin_lock(&fi->lock);
 	/* the kernel maintains i_mtime locally */
 	if (trust_local_cmtime) {
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 0ed13082d0d00d..130395403535dd 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -279,9 +279,11 @@ static int fuse_open(struct inode *inode, struct file *file)
 	if ((is_wb_truncate || dax_truncate) && !is_iomap)
 		fuse_release_nowrite(inode);
 	if (!err) {
-		if (is_truncate)
+		if (is_truncate) {
 			truncate_pagecache(inode, 0);
-		else if (!(ff->open_flags & FOPEN_KEEP_CACHE))
+			if (is_iomap)
+				fuse_iomap_open_truncate(inode);
+		} else if (!(ff->open_flags & FOPEN_KEEP_CACHE))
 			invalidate_inode_pages2(inode->i_mapping);
 	}
 	if (dax_truncate)
@@ -3140,7 +3142,9 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (err)
 		goto out;
 
-	if (!is_iomap)
+	if (is_iomap)
+		fuse_iomap_copied_file_range(inode_out, pos_out, outarg.size);
+	else
 		truncate_inode_pages_range(inode_out->i_mapping,
 				   ALIGN_DOWN(pos_out, PAGE_SIZE),
 				   ALIGN(pos_out + outarg.size, PAGE_SIZE) - 1);
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index b568a862f120ff..b410cae0dec5dd 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -895,6 +895,7 @@ static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t count,
 			fuse_iomap_inline_free(iomap);
 			if (err)
 				return err;
+			fuse_iomap_cache_invalidate_range(inode, pos, written);
 		} else {
 			fuse_iomap_inline_free(iomap);
 		}
@@ -1035,9 +1036,11 @@ static int fuse_iomap_ioend(struct inode *inode, loff_t pos, size_t written,
 
 	/*
 	 * If there weren't any ioend errors, update the incore isize, which
-	 * confusingly takes the new i_size as "pos".
+	 * confusingly takes the new i_size as "pos".  Invalidate cached
+	 * mappings for the file range that we just completed.
 	 */
 	fuse_write_update_attr(inode, pos + written, written);
+	fuse_iomap_cache_invalidate_range(inode, pos, written);
 	return 0;
 }
 
@@ -2220,6 +2223,18 @@ fuse_iomap_setsize_start(
 	return filemap_write_and_wait(inode->i_mapping);
 }
 
+int
+fuse_iomap_setsize_finish(
+	struct inode		*inode,
+	loff_t			newsize)
+{
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	trace_fuse_iomap_setsize(inode, newsize, 0);
+
+	return fuse_iomap_cache_invalidate(inode, newsize);
+}
+
 /*
  * Prepare for a file data block remapping operation by flushing and unmapping
  * all pagecache for the entire range.
@@ -2302,6 +2317,14 @@ fuse_iomap_fallocate(
 
 	trace_fuse_iomap_fallocate(inode, mode, offset, length, new_size);
 
+	if (mode & (FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE))
+		error = fuse_iomap_cache_invalidate(inode, offset);
+	else
+		error = fuse_iomap_cache_invalidate_range(inode, offset,
+							  length);
+	if (error)
+		return error;
+
 	/*
 	 * If we unmapped blocks from the file range, then we zero the
 	 * pagecache for those regions and push them to disk rather than make
@@ -2319,6 +2342,8 @@ fuse_iomap_fallocate(
 	 */
 	if (new_size) {
 		error = fuse_iomap_setsize_start(inode, new_size);
+		if (!error)
+			error = fuse_iomap_setsize_finish(inode, new_size);
 		if (error)
 			return error;
 
@@ -2403,3 +2428,18 @@ int fuse_iomap_dev_inval(struct fuse_conn *fc,
 	up_read(&fc->killsb);
 	return ret;
 }
+
+void fuse_iomap_open_truncate(struct inode *inode)
+{
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	fuse_iomap_cache_invalidate(inode, 0);
+}
+
+void fuse_iomap_copied_file_range(struct inode *inode, loff_t offset,
+				  size_t written)
+{
+	ASSERT(fuse_inode_has_iomap(inode));
+
+	fuse_iomap_cache_invalidate_range(inode, offset, written);
+}
diff --git a/fs/fuse/iomap_cache.c b/fs/fuse/iomap_cache.c
index 572bccf99a97a8..f1be73da571440 100644
--- a/fs/fuse/iomap_cache.c
+++ b/fs/fuse/iomap_cache.c
@@ -1412,6 +1412,33 @@ fuse_iomap_cache_remove(
 	return ret;
 }
 
+int fuse_iomap_cache_invalidate_range(struct inode *inode, loff_t offset,
+				      uint64_t length)
+{
+	loff_t aligned_offset;
+	const unsigned int blocksize = i_blocksize(inode);
+	int ret, ret2;
+
+	if (!fuse_inode_caches_iomaps(inode))
+		return 0;
+
+	aligned_offset = round_down(offset, blocksize);
+	if (length != FUSE_IOMAP_INVAL_TO_EOF) {
+		length += offset - aligned_offset;
+		length = round_up(length, blocksize);
+	}
+
+	fuse_iomap_cache_lock(inode);
+	ret = fuse_iomap_cache_remove(inode, READ_MAPPING,
+				      aligned_offset, length);
+	ret2 = fuse_iomap_cache_remove(inode, WRITE_MAPPING,
+				       aligned_offset, length);
+	fuse_iomap_cache_unlock(inode);
+	if (ret)
+		return ret;
+	return ret2;
+}
+
 static void
 fuse_iext_add_mapping(
 	struct fuse_iomap_cache		*ip,

[PATCH 06/10] fuse_trace: invalidate iomap cache after file updates

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h  |   37 +++++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c  |    4 ++++
 fs/fuse/iomap_cache.c |    2 ++
 3 files changed, 43 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 5f399b1604a2ac..1cfcc64de08817 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -1073,6 +1073,7 @@ DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_truncate_down);
 DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_punch_range);
 DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_setsize);
 DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_flush_unmap_range);
+DEFINE_FUSE_IOMAP_FILE_RANGE_EVENT(fuse_iomap_cache_invalidate_range);
 
 TRACE_EVENT(fuse_iomap_fallocate,
 	TP_PROTO(const struct inode *inode, int mode, loff_t offset,
@@ -1210,6 +1211,42 @@ DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_inline_write);
 DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_set_inline_iomap);
 DEFINE_FUSE_IOMAP_INLINE_EVENT(fuse_iomap_set_inline_srcmap);
 
+TRACE_EVENT(fuse_iomap_open_truncate,
+	TP_PROTO(const struct inode *inode),
+
+	TP_ARGS(inode),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+	),
+
+	TP_printk(FUSE_INODE_FMT,
+		  FUSE_INODE_PRINTK_ARGS)
+);
+
+TRACE_EVENT(fuse_iomap_copied_file_range,
+	TP_PROTO(const struct inode *inode, loff_t offset,
+		 size_t written),
+	TP_ARGS(inode, offset, written),
+
+	TP_STRUCT__entry(
+		FUSE_IO_RANGE_FIELDS()
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->offset		=	offset;
+		__entry->length		=	written;
+	),
+
+	TP_printk(FUSE_IO_RANGE_FMT(),
+		  FUSE_IO_RANGE_PRINTK_ARGS())
+);
+
 DECLARE_EVENT_CLASS(fuse_iext_class,
 	TP_PROTO(const struct inode *inode, const struct fuse_iext_cursor *cur,
 		 int state, unsigned long caller_ip),
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index b410cae0dec5dd..c7b0026bff75f3 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -2433,6 +2433,8 @@ void fuse_iomap_open_truncate(struct inode *inode)
 {
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_open_truncate(inode);
+
 	fuse_iomap_cache_invalidate(inode, 0);
 }
 
@@ -2441,5 +2443,7 @@ void fuse_iomap_copied_file_range(struct inode *inode, loff_t offset,
 {
 	ASSERT(fuse_inode_has_iomap(inode));
 
+	trace_fuse_iomap_copied_file_range(inode, offset, written);
+
 	fuse_iomap_cache_invalidate_range(inode, offset, written);
 }
diff --git a/fs/fuse/iomap_cache.c b/fs/fuse/iomap_cache.c
index f1be73da571440..a13eb5eec72415 100644
--- a/fs/fuse/iomap_cache.c
+++ b/fs/fuse/iomap_cache.c
@@ -1422,6 +1422,8 @@ int fuse_iomap_cache_invalidate_range(struct inode *inode, loff_t offset,
 	if (!fuse_inode_caches_iomaps(inode))
 		return 0;
 
+	trace_fuse_iomap_cache_invalidate_range(inode, offset, length);
+
 	aligned_offset = round_down(offset, blocksize);
 	if (length != FUSE_IOMAP_INVAL_TO_EOF) {
 		length += offset - aligned_offset;

[PATCH 07/10] fuse: enable iomap cache management

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Provide a means for the fuse server to upload iomappings to the kernel
and invalidate them.  This is how we enable iomap caching for better
performance.  This is also required for correct synchronization between
pagecache writes and writeback.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |    7 +
 include/uapi/linux/fuse.h |   28 +++++
 fs/fuse/dev.c             |   44 ++++++++
 fs/fuse/file_iomap.c      |  239 ++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 314 insertions(+), 4 deletions(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index c6ec9383a99ce5..d42737bac0af88 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1858,6 +1858,11 @@ enum fuse_iomap_iodir {
 	READ_MAPPING,
 	WRITE_MAPPING,
 };
+
+int fuse_iomap_upsert(struct fuse_conn *fc,
+		      const struct fuse_iomap_upsert_out *outarg);
+int fuse_iomap_inval(struct fuse_conn *fc,
+		     const struct fuse_iomap_inval_out *outarg);
 #else
 # define fuse_iomap_enabled(...)		(false)
 # define fuse_has_iomap(...)			(false)
@@ -1888,6 +1893,8 @@ enum fuse_iomap_iodir {
 # define fuse_iomap_dev_inval(...)		(-ENOSYS)
 # define fuse_iomap_fadvise			NULL
 # define fuse_inode_caches_iomaps(...)		(false)
+# define fuse_iomap_upsert(...)			(-ENOSYS)
+# define fuse_iomap_inval(...)			(-ENOSYS)
 #endif
 
 #endif /* _FS_FUSE_I_H */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index d4a257517915fd..5c2c594fc87892 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -244,6 +244,8 @@
  *  - add FUSE_ATTR_ATOMIC for single-fsblock atomic write support
  *  - add FUSE_ATTR_{SYNC,IMMUTABLE,APPEND} for VFS enforcement of file
  *    attributes
+ *  - add FUSE_NOTIFY_IOMAP_UPSERT and FUSE_NOTIFY_IOMAP_INVAL so fuse servers
+ *    can cache iomappings in the kernel
  */
 
 #ifndef _LINUX_FUSE_H
@@ -715,6 +717,8 @@ enum fuse_notify_code {
 	FUSE_NOTIFY_RESEND = 7,
 	FUSE_NOTIFY_INC_EPOCH = 8,
 	FUSE_NOTIFY_IOMAP_DEV_INVAL = 9,
+	FUSE_NOTIFY_IOMAP_UPSERT = 10,
+	FUSE_NOTIFY_IOMAP_INVAL = 11,
 	FUSE_NOTIFY_CODE_MAX,
 };
 
@@ -1360,6 +1364,8 @@ struct fuse_uring_cmd_req {
 #define FUSE_IOMAP_TYPE_PURE_OVERWRITE	(255)
 /* fuse-specific mapping type saying the server has populated the cache */
 #define FUSE_IOMAP_TYPE_RETRY_CACHE	(254)
+/* do not upsert this mapping */
+#define FUSE_IOMAP_TYPE_NOCACHE		(253)
 
 #define FUSE_IOMAP_DEV_NULL		(0U)	/* null device cookie */
 
@@ -1505,4 +1511,26 @@ struct fuse_iomap_dev_inval_out {
 /* invalidate all cached iomap mappings up to EOF */
 #define FUSE_IOMAP_INVAL_TO_EOF		(~0ULL)
 
+struct fuse_iomap_inval_out {
+	uint64_t nodeid;	/* Inode ID */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+
+	uint64_t read_offset;	/* range to invalidate read iomaps, bytes */
+	uint64_t read_length;	/* can be FUSE_IOMAP_INVAL_TO_EOF */
+
+	uint64_t write_offset;	/* range to invalidate write iomaps, bytes */
+	uint64_t write_length;	/* can be FUSE_IOMAP_INVAL_TO_EOF */
+};
+
+struct fuse_iomap_upsert_out {
+	uint64_t nodeid;	/* Inode ID */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+
+	/* read file data from here */
+	struct fuse_iomap_io	read;
+
+	/* write file data to here, if applicable */
+	struct fuse_iomap_io	write;
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index adbe2a65e6fe87..b144f67f06160f 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1892,6 +1892,46 @@ static int fuse_notify_iomap_dev_inval(struct fuse_conn *fc, unsigned int size,
 	return err;
 }
 
+static int fuse_notify_iomap_upsert(struct fuse_conn *fc, unsigned int size,
+				    struct fuse_copy_state *cs)
+{
+	struct fuse_iomap_upsert_out outarg;
+	int err = -EINVAL;
+
+	if (size != sizeof(outarg))
+		goto err;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto err;
+	fuse_copy_finish(cs);
+
+	return fuse_iomap_upsert(fc, &outarg);
+err:
+	fuse_copy_finish(cs);
+	return err;
+}
+
+static int fuse_notify_iomap_inval(struct fuse_conn *fc, unsigned int size,
+				   struct fuse_copy_state *cs)
+{
+	struct fuse_iomap_inval_out outarg;
+	int err = -EINVAL;
+
+	if (size != sizeof(outarg))
+		goto err;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto err;
+	fuse_copy_finish(cs);
+
+	return fuse_iomap_inval(fc, &outarg);
+err:
+	fuse_copy_finish(cs);
+	return err;
+}
+
 struct fuse_retrieve_args {
 	struct fuse_args_pages ap;
 	struct fuse_notify_retrieve_in inarg;
@@ -2140,6 +2180,10 @@ static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
 
 	case FUSE_NOTIFY_IOMAP_DEV_INVAL:
 		return fuse_notify_iomap_dev_inval(fc, size, cs);
+	case FUSE_NOTIFY_IOMAP_UPSERT:
+		return fuse_notify_iomap_upsert(fc, size, cs);
+	case FUSE_NOTIFY_IOMAP_INVAL:
+		return fuse_notify_iomap_inval(fc, size, cs);
 
 	default:
 		fuse_copy_finish(cs);
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index c7b0026bff75f3..ff79a30f6ff8d2 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -166,6 +166,7 @@ static inline bool fuse_iomap_check_type(uint16_t fuse_type)
 	case FUSE_IOMAP_TYPE_INLINE:
 	case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
 	case FUSE_IOMAP_TYPE_RETRY_CACHE:
+	case FUSE_IOMAP_TYPE_NOCACHE:
 		return true;
 	}
 
@@ -272,12 +273,13 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
 	uint64_t end;
 
 	/*
-	 * Type and flags must be known.  Mapping type "retry cache" doesn't
-	 * use any of the other fields.
+	 * Type and flags must be known.  Mapping types "retry cache" and "do
+	 * not insert in cache" don't use any of the other fields.
 	 */
 	if (BAD_DATA(!fuse_iomap_check_type(map->type)))
 		return false;
-	if (map->type == FUSE_IOMAP_TYPE_RETRY_CACHE)
+	if (map->type == FUSE_IOMAP_TYPE_RETRY_CACHE ||
+	    map->type == FUSE_IOMAP_TYPE_NOCACHE)
 		return true;
 	if (BAD_DATA(!fuse_iomap_check_flags(map->flags)))
 		return false;
@@ -331,6 +333,9 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
 		if (BAD_DATA(iodir != WRITE_MAPPING))
 			return false;
 		break;
+	case FUSE_IOMAP_TYPE_NOCACHE:
+		/* We're ignoring this mapping */
+		break;
 	default:
 		/* should have been caught already */
 		ASSERT(0);
@@ -386,6 +391,15 @@ fuse_iomap_begin_validate(const struct inode *inode,
 	if (!fuse_iomap_check_mapping(inode, &outarg->write, WRITE_MAPPING))
 		return -EFSCORRUPTED;
 
+	/*
+	 * ->iomap_begin requires real mappings or "retry from cache"; "do not
+	 * add to cache" does not apply here.
+	 */
+	if (BAD_DATA(outarg->read.type == FUSE_IOMAP_TYPE_NOCACHE))
+		return -EFSCORRUPTED;
+	if (BAD_DATA(outarg->write.type == FUSE_IOMAP_TYPE_NOCACHE))
+		return -EFSCORRUPTED;
+
 	/*
 	 * Must have returned a mapping for at least the first byte in the
 	 * range.  The main mapping check already validated that the length
@@ -613,9 +627,11 @@ fuse_iomap_cached_validate(const struct inode *inode,
 	if (!fuse_iomap_check_mapping(inode, &lmap->map, dir))
 		return -EFSCORRUPTED;
 
-	/* The cache should not be storing "retry cache" mappings */
+	/* The cache should not be storing cache management mappings */
 	if (BAD_DATA(lmap->map.type == FUSE_IOMAP_TYPE_RETRY_CACHE))
 		return -EFSCORRUPTED;
+	if (BAD_DATA(lmap->map.type == FUSE_IOMAP_TYPE_NOCACHE))
+		return -EFSCORRUPTED;
 
 	return 0;
 }
@@ -2447,3 +2463,218 @@ void fuse_iomap_copied_file_range(struct inode *inode, loff_t offset,
 
 	fuse_iomap_cache_invalidate_range(inode, offset, written);
 }
+
+static inline bool
+fuse_iomap_upsert_validate_dev(
+	const struct fuse_backing	*fb,
+	const struct fuse_iomap_io	*map)
+{
+	uint64_t			map_end;
+	sector_t			device_bytes;
+
+	if (!fb) {
+		if (BAD_DATA(map->addr != FUSE_IOMAP_NULL_ADDR))
+			return false;
+
+		return true;
+	}
+
+	if (BAD_DATA(map->addr == FUSE_IOMAP_NULL_ADDR))
+		return false;
+
+	if (BAD_DATA(check_add_overflow(map->addr, map->length, &map_end)))
+		return false;
+
+	device_bytes = bdev_nr_sectors(fb->bdev) << SECTOR_SHIFT;
+	if (BAD_DATA(map_end > device_bytes))
+		return false;
+
+	return true;
+}
+
+/* Validate one of the incoming upsert mappings */
+static inline bool
+fuse_iomap_upsert_validate_mapping(struct inode *inode,
+				   enum fuse_iomap_iodir iodir,
+				   const struct fuse_iomap_io *map)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_backing *fb;
+	bool ret;
+
+	if (!fuse_iomap_check_mapping(inode, map, iodir))
+		return false;
+
+	/*
+	 * A "retry cache" instruction makes no sense when we're adding to
+	 * the mapping cache.
+	 */
+	if (BAD_DATA(map->type == FUSE_IOMAP_TYPE_RETRY_CACHE))
+		return false;
+
+	if (map->type == FUSE_IOMAP_TYPE_NOCACHE)
+		return true;
+
+	/* Make sure we can find the device */
+	fb = fuse_iomap_find_dev(fc, map);
+	if (IS_ERR(fb))
+		return false;
+
+	ret = fuse_iomap_upsert_validate_dev(fb, map);
+	fuse_backing_put(fb);
+	return ret;
+}
+
+/* Check the incoming upsert mappings to make sure they're not nonsense */
+static inline int
+fuse_iomap_upsert_validate(struct inode *inode,
+			   const struct fuse_iomap_upsert_out *outarg)
+{
+	if (!fuse_iomap_upsert_validate_mapping(inode, READ_MAPPING,
+						&outarg->read))
+		return -EFSCORRUPTED;
+	if (!fuse_iomap_upsert_validate_mapping(inode, WRITE_MAPPING,
+						&outarg->write))
+		return -EFSCORRUPTED;
+
+	return 0;
+}
+
+int fuse_iomap_upsert(struct fuse_conn *fc,
+		      const struct fuse_iomap_upsert_out *outarg)
+{
+	struct inode *inode;
+	struct fuse_inode *fi;
+	int ret;
+
+	if (!fc->iomap)
+		return -EINVAL;
+
+	down_read(&fc->killsb);
+	inode = fuse_ilookup(fc, outarg->nodeid, NULL);
+	if (!inode) {
+		ret = -ESTALE;
+		goto out_sb;
+	}
+
+	fi = get_fuse_inode(inode);
+	if (BAD_DATA(fi->orig_ino != outarg->attr_ino)) {
+		ret = -EINVAL;
+		goto out_inode;
+	}
+
+	if (fuse_is_bad(inode)) {
+		ret = -EIO;
+		goto out_inode;
+	}
+
+	ret = fuse_iomap_upsert_validate(inode, outarg);
+	if (ret)
+		goto out_inode;
+
+	fuse_iomap_cache_lock(inode);
+
+	set_bit(FUSE_I_IOMAP_CACHE, &fi->state);
+
+	if (outarg->read.type != FUSE_IOMAP_TYPE_NOCACHE) {
+		ret = fuse_iomap_cache_upsert(inode, READ_MAPPING,
+					      &outarg->read);
+		if (ret)
+			goto out_unlock;
+	}
+
+	if (outarg->write.type != FUSE_IOMAP_TYPE_NOCACHE) {
+		ret = fuse_iomap_cache_upsert(inode, WRITE_MAPPING,
+					      &outarg->write);
+		if (ret)
+			goto out_unlock;
+	}
+
+out_unlock:
+	fuse_iomap_cache_unlock(inode);
+out_inode:
+	iput(inode);
+out_sb:
+	up_read(&fc->killsb);
+	return ret;
+}
+
+static inline bool fuse_iomap_inval_validate(const struct inode *inode,
+					     uint64_t offset, uint64_t length)
+{
+	const unsigned int blocksize = i_blocksize(inode);
+
+	if (length == 0)
+		return true;
+
+	/* Range can't start beyond maxbytes */
+	if (BAD_DATA(offset >= inode->i_sb->s_maxbytes))
+		return false;
+
+	/* File range must be aligned to blocksize */
+	if (BAD_DATA(!IS_ALIGNED(offset, blocksize)))
+		return false;
+	if (length != FUSE_IOMAP_INVAL_TO_EOF &&
+	    BAD_DATA(!IS_ALIGNED(length, blocksize)))
+		return false;
+
+	return true;
+}
+
+int fuse_iomap_inval(struct fuse_conn *fc,
+		     const struct fuse_iomap_inval_out *outarg)
+{
+	struct inode *inode;
+	struct fuse_inode *fi;
+	int ret = 0, ret2 = 0;
+
+	if (!fc->iomap)
+		return -EINVAL;
+
+	down_read(&fc->killsb);
+	inode = fuse_ilookup(fc, outarg->nodeid, NULL);
+	if (!inode) {
+		ret = -ESTALE;
+		goto out_sb;
+	}
+
+	fi = get_fuse_inode(inode);
+	if (BAD_DATA(fi->orig_ino != outarg->attr_ino)) {
+		ret = -EINVAL;
+		goto out_inode;
+	}
+
+	if (fuse_is_bad(inode)) {
+		ret = -EIO;
+		goto out_inode;
+	}
+
+	if (!fuse_iomap_inval_validate(inode, outarg->write_offset,
+				       outarg->write_length)) {
+		ret = -EFSCORRUPTED;
+		goto out_inode;
+	}
+
+	if (!fuse_iomap_inval_validate(inode, outarg->read_offset,
+				       outarg->read_length)) {
+		ret = -EFSCORRUPTED;
+		goto out_inode;
+	}
+
+	fuse_iomap_cache_lock(inode);
+	if (outarg->read_length)
+		ret2 = fuse_iomap_cache_remove(inode, READ_MAPPING,
+					       outarg->read_offset,
+					       outarg->read_length);
+	if (outarg->write_length)
+		ret = fuse_iomap_cache_remove(inode, WRITE_MAPPING,
+					      outarg->write_offset,
+					      outarg->write_length);
+	fuse_iomap_cache_unlock(inode);
+
+out_inode:
+	iput(inode);
+out_sb:
+	up_read(&fc->killsb);
+	return ret ? ret : ret2;
+}

[PATCH 08/10] fuse_trace: enable iomap cache management

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracepoints for the previous patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h |   68 ++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/file_iomap.c |    7 ++++-
 2 files changed, 74 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 1cfcc64de08817..202fc32f6b02e1 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -401,6 +401,7 @@ struct fuse_iomap_lookup;
 #define FUSE_IOMAP_TYPE_STRINGS \
 	{ FUSE_IOMAP_TYPE_PURE_OVERWRITE,	"overwrite" }, \
 	{ FUSE_IOMAP_TYPE_RETRY_CACHE,		"retry" }, \
+	{ FUSE_IOMAP_TYPE_NOCACHE,		"nocache" }, \
 	{ FUSE_IOMAP_TYPE_HOLE,			"hole" }, \
 	{ FUSE_IOMAP_TYPE_DELALLOC,		"delalloc" }, \
 	{ FUSE_IOMAP_TYPE_MAPPED,		"mapped" }, \
@@ -742,6 +743,7 @@ DEFINE_EVENT(fuse_inode_state_class, name,	\
 	TP_ARGS(inode))
 DEFINE_FUSE_INODE_STATE_EVENT(fuse_iomap_init_inode);
 DEFINE_FUSE_INODE_STATE_EVENT(fuse_iomap_evict_inode);
+DEFINE_FUSE_INODE_STATE_EVENT(fuse_iomap_cache_enable);
 
 TRACE_EVENT(fuse_iomap_fiemap,
 	TP_PROTO(const struct inode *inode, u64 start, u64 count,
@@ -1542,6 +1544,72 @@ TRACE_EVENT(fuse_iomap_invalid,
 		  __entry->old_validity_cookie,
 		  __entry->validity_cookie)
 );
+
+TRACE_EVENT(fuse_iomap_upsert,
+	TP_PROTO(const struct inode *inode,
+		 const struct fuse_iomap_upsert_out *outarg),
+	TP_ARGS(inode, outarg),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		__field(uint64_t,		attr_ino)
+
+		FUSE_IOMAP_MAP_FIELDS(read)
+		FUSE_IOMAP_MAP_FIELDS(write)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->attr_ino	=	outarg->attr_ino;
+		__entry->readoffset	=	outarg->read.offset;
+		__entry->readlength	=	outarg->read.length;
+		__entry->readaddr	=	outarg->read.addr;
+		__entry->readtype	=	outarg->read.type;
+		__entry->readflags	=	outarg->read.flags;
+		__entry->readdev	=	outarg->read.dev;
+		__entry->writeoffset	=	outarg->write.offset;
+		__entry->writelength	=	outarg->write.length;
+		__entry->writeaddr	=	outarg->write.addr;
+		__entry->writetype	=	outarg->write.type;
+		__entry->writeflags	=	outarg->write.flags;
+		__entry->writedev	=	outarg->write.dev;
+	),
+
+	TP_printk(FUSE_INODE_FMT " attr_ino 0x%llx" FUSE_IOMAP_MAP_FMT("read") FUSE_IOMAP_MAP_FMT("write"),
+		  FUSE_INODE_PRINTK_ARGS,
+		  __entry->attr_ino,
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(read),
+		  FUSE_IOMAP_MAP_PRINTK_ARGS(write))
+);
+
+TRACE_EVENT(fuse_iomap_inval,
+	TP_PROTO(const struct inode *inode,
+		 const struct fuse_iomap_inval_out *outarg),
+	TP_ARGS(inode, outarg),
+
+	TP_STRUCT__entry(
+		FUSE_INODE_FIELDS
+		__field(uint64_t,		attr_ino)
+
+		FUSE_FILE_RANGE_FIELDS(read)
+		FUSE_FILE_RANGE_FIELDS(write)
+	),
+
+	TP_fast_assign(
+		FUSE_INODE_ASSIGN(inode, fi, fm);
+		__entry->attr_ino	=	outarg->attr_ino;
+		__entry->readoffset	=	outarg->read_offset;
+		__entry->readlength	=	outarg->read_length;
+		__entry->writeoffset	=	outarg->write_offset;
+		__entry->writelength	=	outarg->write_length;
+	),
+
+	TP_printk(FUSE_INODE_FMT " attr_ino 0x%llx" FUSE_FILE_RANGE_FMT("read") FUSE_FILE_RANGE_FMT("write"),
+		  FUSE_INODE_PRINTK_ARGS,
+		  __entry->attr_ino,
+		  FUSE_FILE_RANGE_PRINTK_ARGS(read),
+		  FUSE_FILE_RANGE_PRINTK_ARGS(write))
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index ff79a30f6ff8d2..c82434674fb52b 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -2557,6 +2557,8 @@ int fuse_iomap_upsert(struct fuse_conn *fc,
 		goto out_sb;
 	}
 
+	trace_fuse_iomap_upsert(inode, outarg);
+
 	fi = get_fuse_inode(inode);
 	if (BAD_DATA(fi->orig_ino != outarg->attr_ino)) {
 		ret = -EINVAL;
@@ -2574,7 +2576,8 @@ int fuse_iomap_upsert(struct fuse_conn *fc,
 
 	fuse_iomap_cache_lock(inode);
 
-	set_bit(FUSE_I_IOMAP_CACHE, &fi->state);
+	if (!test_and_set_bit(FUSE_I_IOMAP_CACHE, &fi->state))
+		trace_fuse_iomap_cache_enable(inode);
 
 	if (outarg->read.type != FUSE_IOMAP_TYPE_NOCACHE) {
 		ret = fuse_iomap_cache_upsert(inode, READ_MAPPING,
@@ -2638,6 +2641,8 @@ int fuse_iomap_inval(struct fuse_conn *fc,
 		goto out_sb;
 	}
 
+	trace_fuse_iomap_inval(inode, outarg);
+
 	fi = get_fuse_inode(inode);
 	if (BAD_DATA(fi->orig_ino != outarg->attr_ino)) {
 		ret = -EINVAL;

[PATCH 09/10] fuse: overlay iomap inode info in struct fuse_inode

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

It's not possible for a regular file to use iomap mode and writeback
caching at the same time, so we can save some memory in struct
fuse_inode by overlaying them in the union.  This is a separate patch
because C unions are rather unsafe and I prefer any errors to be
bisectable to this patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index d42737bac0af88..8238c1cfd9c481 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -197,8 +197,11 @@ struct fuse_inode {
 
 			/* waitq for direct-io completion */
 			wait_queue_head_t direct_io_waitq;
+		};
 
 #ifdef CONFIG_FUSE_IOMAP
+		/* regular file iomap mode */
+		struct {
 			/* pending io completions */
 			spinlock_t ioend_lock;
 			struct work_struct ioend_work;
@@ -206,8 +209,8 @@ struct fuse_inode {
 
 			/* cached iomap mappings */
 			struct fuse_iomap_cache cache;
-#endif
 		};
+#endif
 
 		/* readdir cache (directory only) */
 		struct {

[PATCH 10/10] fuse: enable iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Remove the guard that we used to avoid bisection problems.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/file_iomap.c |    3 ---
 1 file changed, 3 deletions(-)


diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index c82434674fb52b..261490a322c289 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -104,9 +104,6 @@ void fuse_iomap_sysfs_cleanup(struct kobject *fuse_kobj)
 
 bool fuse_iomap_enabled(void)
 {
-	/* Don't let anyone touch iomap until the end of the patchset. */
-	return false;
-
 	/*
 	 * There are fears that a fuse+iomap server could somehow DoS the
 	 * system by doing things like going out to lunch during a writeback

[PATCH 1/2] fuse: allow privileged mount helpers to pre-approve iomap usage

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

For the upcoming safemount functionality in libfuse, we will create a
privileged "mount.safe" helper that starts the fuse server in a
completely unprivileged systemd container.  The mount helper will pass
the mount options and fds for /dev/fuse and any other files requested by
the fuse server into the container via a Unix socket.

Currently, the ability to turn on iomap for fuse depends on a module
parameter and the process that calls mount() having the CAP_SYS_RAWIO
capability.  However, the unprivilged fuse server might want to query
the /dev/fuse fd for iomap capabilities before mount or FUSE_INIT so
that it can get ready.

Similar to FUSE_DEV_SYNC_INIT, add a new bit for iomap that can be
squirreled away in file->private_data and an ioctl to set that bit.
That way the privileged mount helper can pass its iomap privilege to the
contained fuse server without the fuse server needing to have
CAP_SYS_RAWIO.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_dev_i.h      |   32 +++++++++++++++++++++++++++++---
 fs/fuse/fuse_i.h          |    9 +++++++++
 include/uapi/linux/fuse.h |    1 +
 fs/fuse/dev.c             |   11 +++++------
 fs/fuse/file_iomap.c      |   43 ++++++++++++++++++++++++++++++++++++++++++-
 fs/fuse/inode.c           |   18 ++++++++++++------
 6 files changed, 98 insertions(+), 16 deletions(-)


diff --git a/fs/fuse/fuse_dev_i.h b/fs/fuse/fuse_dev_i.h
index 6e8373f970409e..783ab1432c8691 100644
--- a/fs/fuse/fuse_dev_i.h
+++ b/fs/fuse/fuse_dev_i.h
@@ -39,8 +39,10 @@ struct fuse_copy_state {
 	} ring;
 };
 
-#define FUSE_DEV_SYNC_INIT ((struct fuse_dev *) 1)
-#define FUSE_DEV_PTR_MASK (~1UL)
+#define FUSE_DEV_SYNC_INIT	(1UL << 0)
+#define FUSE_DEV_INHERIT_IOMAP	(1UL << 1)
+#define FUSE_DEV_FLAGS_MASK	(FUSE_DEV_SYNC_INIT | FUSE_DEV_INHERIT_IOMAP)
+#define FUSE_DEV_PTR_MASK	(~FUSE_DEV_FLAGS_MASK)
 
 static inline struct fuse_dev *__fuse_get_dev(struct file *file)
 {
@@ -50,7 +52,31 @@ static inline struct fuse_dev *__fuse_get_dev(struct file *file)
 	 */
 	struct fuse_dev *fud = READ_ONCE(file->private_data);
 
-	return (typeof(fud)) ((unsigned long) fud & FUSE_DEV_PTR_MASK);
+	return (typeof(fud)) ((uintptr_t)fud & FUSE_DEV_PTR_MASK);
+}
+
+static inline struct fuse_dev *__fuse_get_dev_and_flags(struct file *file,
+							uintptr_t *flagsp)
+{
+	/*
+	 * Lockless access is OK, because file->private data is set
+	 * once during mount and is valid until the file is released.
+	 */
+	struct fuse_dev *fud = READ_ONCE(file->private_data);
+
+	*flagsp = ((uintptr_t)fud) & FUSE_DEV_FLAGS_MASK;
+	return (typeof(fud)) ((uintptr_t) fud & FUSE_DEV_PTR_MASK);
+}
+
+static inline int __fuse_set_dev_flags(struct file *file, uintptr_t flag)
+{
+	uintptr_t old_flags = 0;
+
+	if (__fuse_get_dev_and_flags(file, &old_flags))
+		return -EINVAL;
+
+	WRITE_ONCE(file->private_data, (struct fuse_dev *)(old_flags | flag));
+	return 0;
 }
 
 struct fuse_dev *fuse_get_dev(struct file *file);
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 8238c1cfd9c481..1a965d3dee6479 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -984,6 +984,13 @@ struct fuse_conn {
 	/* Enable fs/iomap for file operations */
 	unsigned int iomap:1;
 
+	/*
+	 * Are filesystems using this connection allowed to use iomap?  This is
+	 * determined by the privilege level of the process that initiated the
+	 * mount() call.
+	 */
+	unsigned int may_iomap:1;
+
 	/* Use io_uring for communication */
 	unsigned int io_uring;
 
@@ -1843,6 +1850,7 @@ void fuse_iomap_open_truncate(struct inode *inode);
 void fuse_iomap_copied_file_range(struct inode *inode, loff_t offset,
 				  size_t written);
 
+int fuse_dev_ioctl_add_iomap(struct file *file);
 int fuse_dev_ioctl_iomap_support(struct file *file,
 				 struct fuse_iomap_support __user *argp);
 int fuse_iomap_dev_inval(struct fuse_conn *fc,
@@ -1892,6 +1900,7 @@ int fuse_iomap_inval(struct fuse_conn *fc,
 # define fuse_iomap_flush_unmap_range(...)	(-ENOSYS)
 # define fuse_iomap_open_truncate(...)		((void)0)
 # define fuse_iomap_copied_file_range(...)	((void)0)
+# define fuse_dev_ioctl_add_iomap(...)		(-EOPNOTSUPP)
 # define fuse_dev_ioctl_iomap_support(...)	(-EOPNOTSUPP)
 # define fuse_iomap_dev_inval(...)		(-ENOSYS)
 # define fuse_iomap_fadvise			NULL
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 5c2c594fc87892..b59ce131513efd 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1187,6 +1187,7 @@ struct fuse_iomap_support {
 					     struct fuse_backing_map)
 #define FUSE_DEV_IOC_BACKING_CLOSE	_IOW(FUSE_DEV_IOC_MAGIC, 2, uint32_t)
 #define FUSE_DEV_IOC_SYNC_INIT		_IO(FUSE_DEV_IOC_MAGIC, 3)
+#define FUSE_DEV_IOC_ADD_IOMAP		_IO(FUSE_DEV_IOC_MAGIC, 99)
 #define FUSE_DEV_IOC_IOMAP_SUPPORT	_IOR(FUSE_DEV_IOC_MAGIC, 99, \
 					     struct fuse_iomap_support)
 
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index b144f67f06160f..7a24fbcdb2f919 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1556,7 +1556,7 @@ struct fuse_dev *fuse_get_dev(struct file *file)
 		return fud;
 
 	err = wait_event_interruptible(fuse_dev_waitq,
-				       READ_ONCE(file->private_data) != FUSE_DEV_SYNC_INIT);
+				       __fuse_get_dev(file) != NULL);
 	if (err)
 		return ERR_PTR(err);
 
@@ -2752,13 +2752,10 @@ static long fuse_dev_ioctl_backing_close(struct file *file, __u32 __user *argp)
 
 static long fuse_dev_ioctl_sync_init(struct file *file)
 {
-	int err = -EINVAL;
+	int err;
 
 	mutex_lock(&fuse_mutex);
-	if (!__fuse_get_dev(file)) {
-		WRITE_ONCE(file->private_data, FUSE_DEV_SYNC_INIT);
-		err = 0;
-	}
+	err = __fuse_set_dev_flags(file, FUSE_DEV_SYNC_INIT);
 	mutex_unlock(&fuse_mutex);
 	return err;
 }
@@ -2783,6 +2780,8 @@ static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 
 	case FUSE_DEV_IOC_IOMAP_SUPPORT:
 		return fuse_dev_ioctl_iomap_support(file, argp);
+	case FUSE_DEV_IOC_ADD_IOMAP:
+		return fuse_dev_ioctl_add_iomap(file);
 
 	default:
 		return -ENOTTY;
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 261490a322c289..70b01638006a2e 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -9,6 +9,7 @@
 #include <linux/falloc.h>
 #include <linux/fadvise.h>
 #include "fuse_i.h"
+#include "fuse_dev_i.h"
 #include "fuse_trace.h"
 #include "iomap_priv.h"
 
@@ -114,6 +115,12 @@ bool fuse_iomap_enabled(void)
 	return enable_iomap && has_capability_noaudit(current, CAP_SYS_RAWIO);
 }
 
+static inline bool fuse_iomap_may_enable(void)
+{
+	/* Same as above, but this time we log the denial in audit log */
+	return enable_iomap && capable(CAP_SYS_RAWIO);
+}
+
 /* Convert IOMAP_* mapping types to FUSE_IOMAP_TYPE_* */
 #define XMAP(word) \
 	case IOMAP_##word: \
@@ -2367,12 +2374,46 @@ fuse_iomap_fallocate(
 	return 0;
 }
 
+int fuse_dev_ioctl_add_iomap(struct file *file)
+{
+	uintptr_t flags = 0;
+	struct fuse_dev *fud;
+	int ret = 0;
+
+	mutex_lock(&fuse_mutex);
+	fud = __fuse_get_dev_and_flags(file, &flags);
+	if (fud) {
+		if (!fud->fc->may_iomap && !fuse_iomap_may_enable()) {
+			ret = -EPERM;
+			goto out_unlock;
+		}
+
+		fud->fc->may_iomap = 1;
+		goto out_unlock;
+	}
+
+	if (!(flags & FUSE_DEV_INHERIT_IOMAP) && !fuse_iomap_may_enable()) {
+		ret = -EPERM;
+		goto out_unlock;
+	}
+
+	ret = __fuse_set_dev_flags(file, FUSE_DEV_INHERIT_IOMAP);
+
+out_unlock:
+	mutex_unlock(&fuse_mutex);
+	return ret;
+}
+
 int fuse_dev_ioctl_iomap_support(struct file *file,
 				 struct fuse_iomap_support __user *argp)
 {
 	struct fuse_iomap_support ios = { };
+	uintptr_t flags = 0;
+	struct fuse_dev *fud = __fuse_get_dev_and_flags(file, &flags);
 
-	if (fuse_iomap_enabled())
+	if ((!fud && (flags & FUSE_DEV_INHERIT_IOMAP)) ||
+	    (fud && fud->fc->may_iomap) ||
+	    fuse_iomap_enabled())
 		ios.flags = FUSE_IOMAP_SUPPORT_FILEIO |
 			    FUSE_IOMAP_SUPPORT_ATOMIC;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index c29a8cbc55fa27..19b385b79f7cbe 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1022,6 +1022,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
 	fc->name_max = FUSE_NAME_LOW_MAX;
 	fc->timeout.req_timeout = 0;
 	fc->root_nodeid = FUSE_ROOT_ID;
+	fc->may_iomap = fuse_iomap_enabled();
 
 	if (IS_ENABLED(CONFIG_FUSE_BACKING))
 		fuse_backing_files_init(fc);
@@ -1481,7 +1482,7 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
 			if (flags & FUSE_REQUEST_TIMEOUT)
 				timeout = arg->request_timeout;
 
-			if ((flags & FUSE_IOMAP) && fuse_iomap_enabled()) {
+			if ((flags & FUSE_IOMAP) && fc->may_iomap) {
 				fc->local_fs = 1;
 				fc->iomap = 1;
 				printk(KERN_WARNING
@@ -1569,7 +1570,7 @@ static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
 	 */
 	if (fuse_uring_enabled())
 		flags |= FUSE_OVER_IO_URING;
-	if (fuse_iomap_enabled())
+	if (fm->fc->may_iomap)
 		flags |= FUSE_IOMAP;
 
 	ia->in.flags = flags;
@@ -1955,11 +1956,16 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 
 	mutex_lock(&fuse_mutex);
 	err = -EINVAL;
-	if (ctx->fudptr && *ctx->fudptr) {
-		if (*ctx->fudptr == FUSE_DEV_SYNC_INIT) {
-			fc->sync_init = 1;
-		} else
+	if (ctx->fudptr) {
+		uintptr_t raw = (uintptr_t)(*ctx->fudptr);
+		uintptr_t flags = raw & FUSE_DEV_FLAGS_MASK;
+
+		if (raw & FUSE_DEV_PTR_MASK)
 			goto err_unlock;
+		if (flags & FUSE_DEV_SYNC_INIT)
+			fc->sync_init = 1;
+		if (flags & FUSE_DEV_INHERIT_IOMAP)
+			fc->may_iomap = 1;
 	}
 
 	err = fuse_ctl_add_conn(fc);

[PATCH 2/2] fuse: set iomap backing device block size

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add a new ioctl so that an unprivileged fuse server can set the block
size of a bdev that's opened for iomap usage.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_i.h          |    3 +++
 include/uapi/linux/fuse.h |    7 +++++++
 fs/fuse/dev.c             |    2 ++
 fs/fuse/file_iomap.c      |   24 ++++++++++++++++++++++++
 4 files changed, 36 insertions(+)


diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 1a965d3dee6479..faef0efe6a9506 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1853,6 +1853,8 @@ void fuse_iomap_copied_file_range(struct inode *inode, loff_t offset,
 int fuse_dev_ioctl_add_iomap(struct file *file);
 int fuse_dev_ioctl_iomap_support(struct file *file,
 				 struct fuse_iomap_support __user *argp);
+int fuse_dev_ioctl_iomap_set_blocksize(struct file *file,
+				struct fuse_iomap_backing_info __user *argp);
 int fuse_iomap_dev_inval(struct fuse_conn *fc,
 			 const struct fuse_iomap_dev_inval_out *arg);
 
@@ -1902,6 +1904,7 @@ int fuse_iomap_inval(struct fuse_conn *fc,
 # define fuse_iomap_copied_file_range(...)	((void)0)
 # define fuse_dev_ioctl_add_iomap(...)		(-EOPNOTSUPP)
 # define fuse_dev_ioctl_iomap_support(...)	(-EOPNOTSUPP)
+# define fuse_dev_ioctl_iomap_set_blocksize(...) (-EOPNOTSUPP)
 # define fuse_iomap_dev_inval(...)		(-ENOSYS)
 # define fuse_iomap_fadvise			NULL
 # define fuse_inode_caches_iomaps(...)		(false)
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index b59ce131513efd..d360c39be43104 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1180,6 +1180,11 @@ struct fuse_iomap_support {
 	uint64_t	padding;
 };
 
+struct fuse_iomap_backing_info {
+	uint32_t	backing_id;
+	uint32_t	blocksize;
+};
+
 /* Device ioctls: */
 #define FUSE_DEV_IOC_MAGIC		229
 #define FUSE_DEV_IOC_CLONE		_IOR(FUSE_DEV_IOC_MAGIC, 0, uint32_t)
@@ -1190,6 +1195,8 @@ struct fuse_iomap_support {
 #define FUSE_DEV_IOC_ADD_IOMAP		_IO(FUSE_DEV_IOC_MAGIC, 99)
 #define FUSE_DEV_IOC_IOMAP_SUPPORT	_IOR(FUSE_DEV_IOC_MAGIC, 99, \
 					     struct fuse_iomap_support)
+#define FUSE_DEV_IOC_IOMAP_SET_BLOCKSIZE _IOW(FUSE_DEV_IOC_MAGIC, 99, \
+					      struct fuse_iomap_backing_info)
 
 struct fuse_lseek_in {
 	uint64_t	fh;
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 7a24fbcdb2f919..5003a862daf37a 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2782,6 +2782,8 @@ static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 		return fuse_dev_ioctl_iomap_support(file, argp);
 	case FUSE_DEV_IOC_ADD_IOMAP:
 		return fuse_dev_ioctl_add_iomap(file);
+	case FUSE_DEV_IOC_IOMAP_SET_BLOCKSIZE:
+		return fuse_dev_ioctl_iomap_set_blocksize(file, argp);
 
 	default:
 		return -ENOTTY;
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 70b01638006a2e..a915cc9520b532 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -2721,3 +2721,27 @@ int fuse_iomap_inval(struct fuse_conn *fc,
 	up_read(&fc->killsb);
 	return ret ? ret : ret2;
 }
+
+int fuse_dev_ioctl_iomap_set_blocksize(struct file *file,
+				struct fuse_iomap_backing_info __user *argp)
+{
+	struct fuse_iomap_backing_info fbi;
+	struct fuse_dev *fud = fuse_get_dev(file);
+	struct fuse_backing *fb;
+	int ret;
+
+	if (IS_ERR(fud))
+		return PTR_ERR(fud);
+
+	if (copy_from_user(&fbi, argp, sizeof(fbi)))
+		return -EFAULT;
+
+	fb = fuse_backing_lookup(fud->fc, &fuse_iomap_backing_ops,
+				 fbi.backing_id);
+	if (!fb)
+		return -ENOENT;
+
+	ret = set_blocksize(fb->file, fbi.blocksize);
+	fuse_backing_put(fb);
+	return ret;
+}

[PATCH 1/1] libfuse: don't put HAVE_STATX in a public header

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

fuse.h and fuse_lowlevel.h are public headers, don't expose internal
build system config variables to downstream clients.  This can also lead
to function pointer ordering issues if (say) libfuse gets built with
HAVE_STATX but the client program doesn't define a HAVE_STATX.

Get rid of the conditionals in the public header files to fix this.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h           |    2 --
 include/fuse_lowlevel.h  |    2 --
 example/memfs_ll.cc      |    2 +-
 example/passthrough.c    |    2 +-
 example/passthrough_fh.c |    2 +-
 example/passthrough_ll.c |    2 +-
 6 files changed, 4 insertions(+), 8 deletions(-)


diff --git a/include/fuse.h b/include/fuse.h
index 06feacb070fbfb..209102651e9454 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -854,7 +854,6 @@ struct fuse_operations {
 	 */
 	off_t (*lseek) (const char *, off_t off, int whence, struct fuse_file_info *);
 
-#ifdef HAVE_STATX
 	/**
 	 * Get extended file attributes.
 	 *
@@ -865,7 +864,6 @@ struct fuse_operations {
 	 */
 	int (*statx)(const char *path, int flags, int mask, struct statx *stxbuf,
 		     struct fuse_file_info *fi);
-#endif
 };
 
 /** Extra context that may be needed by some filesystems
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index dc4ec07e6dbb00..a6cce014391aec 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1327,7 +1327,6 @@ struct fuse_lowlevel_ops {
 	void (*tmpfile) (fuse_req_t req, fuse_ino_t parent,
 			mode_t mode, struct fuse_file_info *fi);
 
-#ifdef HAVE_STATX
 	/**
 	 * Get extended file attributes.
 	 *
@@ -1343,7 +1342,6 @@ struct fuse_lowlevel_ops {
 	 */
 	void (*statx)(fuse_req_t req, fuse_ino_t ino, int flags, int mask,
 		      struct fuse_file_info *fi);
-#endif
 };
 
 /**
diff --git a/example/memfs_ll.cc b/example/memfs_ll.cc
index edda34b4e43d39..7055a434a439cd 100644
--- a/example/memfs_ll.cc
+++ b/example/memfs_ll.cc
@@ -6,7 +6,7 @@
   See the file GPL2.txt.
 */
 
-#define FUSE_USE_VERSION 317
+#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 18)
 
 #include <algorithm>
 #include <stdio.h>
diff --git a/example/passthrough.c b/example/passthrough.c
index fdaa19e331a17d..1f09c2dc05df1e 100644
--- a/example/passthrough.c
+++ b/example/passthrough.c
@@ -23,7 +23,7 @@
  */
 
 
-#define FUSE_USE_VERSION 31
+#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 18)
 
 #define _GNU_SOURCE
 
diff --git a/example/passthrough_fh.c b/example/passthrough_fh.c
index 0d4fb5bd4df0d6..6403fbb74c7759 100644
--- a/example/passthrough_fh.c
+++ b/example/passthrough_fh.c
@@ -23,7 +23,7 @@
  * \include passthrough_fh.c
  */
 
-#define FUSE_USE_VERSION 31
+#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 18)
 
 #define _GNU_SOURCE
 
diff --git a/example/passthrough_ll.c b/example/passthrough_ll.c
index 5ca6efa2300abe..8a5ac2e9226b59 100644
--- a/example/passthrough_ll.c
+++ b/example/passthrough_ll.c
@@ -35,7 +35,7 @@
  */
 
 #define _GNU_SOURCE
-#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 12)
+#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 18)
 
 #include <fuse_lowlevel.h>
 #include <unistd.h>

[PATCH 01/18] libfuse: bump kernel and library ABI versions

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Bump the kernel ABI version to 7.99 and the libfuse ABI version to 3.99
to start our development.  This patch exists to avoid confusion during
the prototyping stage.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_kernel.h  |    4 +++-
 ChangeLog.rst          |   12 +++++++++++-
 lib/fuse_versionscript |    3 +++
 lib/meson.build        |    2 +-
 meson.build            |    2 +-
 5 files changed, 19 insertions(+), 4 deletions(-)


diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 122d6586e8d4da..4d68c4e8a71d5f 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -235,6 +235,8 @@
  *
  *  7.44
  *  - add FUSE_NOTIFY_INC_EPOCH
+ *
+ *  7.99
  */
 
 #ifndef _LINUX_FUSE_H
@@ -270,7 +272,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 44
+#define FUSE_KERNEL_MINOR_VERSION 99
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
diff --git a/ChangeLog.rst b/ChangeLog.rst
index 505d9dba84100f..bdb133a5f7db74 100644
--- a/ChangeLog.rst
+++ b/ChangeLog.rst
@@ -1,4 +1,14 @@
-libfuse 3.18
+libfuse 3.99
+
+libfuse 3.99-rc0 (2025-07-18)
+===============================
+
+* Add prototypes of iomap and syncfs (djwong)
+
+libfuse 3.18-rc0 (2025-07-18)
+===============================
+
+* Add statx, among other things (djwong)
 
 libfuse 3.17.1-rc0 (2024-02.10)
 ===============================
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 2feafcf83860c5..96a94e43f73909 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -218,6 +218,9 @@ FUSE_3.18 {
 		fuse_fs_statx;
 } FUSE_3.17;
 
+FUSE_3.99 {
+} FUSE_3.18;
+
 # Local Variables:
 # indent-tabs-mode: t
 # End:
diff --git a/lib/meson.build b/lib/meson.build
index fcd95741c9d374..8efe71abfabc9e 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -49,7 +49,7 @@ libfuse = library('fuse3',
                   dependencies: deps,
                   install: true,
                   link_depends: 'fuse_versionscript',
-                  c_args: [ '-DFUSE_USE_VERSION=317',
+                  c_args: [ '-DFUSE_USE_VERSION=399',
                             '-DFUSERMOUNT_DIR="@0@"'.format(fusermount_path) ],
                   link_args: ['-Wl,--version-script,' + meson.current_source_dir()
                               + '/fuse_versionscript' ])
diff --git a/meson.build b/meson.build
index 07c729581789e1..7214d24705c7fb 100644
--- a/meson.build
+++ b/meson.build
@@ -1,5 +1,5 @@
 project('libfuse3', ['c'],
-        version: '3.18.0-rc0',  # Version with RC suffix
+        version: '3.99.0-rc0',  # Version with RC suffix
         meson_version: '>= 0.60.0',
         default_options: [
             'buildtype=debugoptimized',

[PATCH 02/18] libfuse: add kernel gates for FUSE_IOMAP

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add some flags to query and request kernel support for filesystem iomap
for regular files.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h |    5 +++++
 include/fuse_kernel.h |    3 +++
 lib/fuse_lowlevel.c   |   12 +++++++++++-
 3 files changed, 19 insertions(+), 1 deletion(-)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index 041188ec7fa732..9d53354de78868 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -512,6 +512,11 @@ struct fuse_loop_config_v1 {
  */
 #define FUSE_CAP_OVER_IO_URING (1UL << 31)
 
+/**
+ * Client supports using iomap for regular file operations
+ */
+#define FUSE_CAP_IOMAP (1ULL << 32)
+
 /**
  * Ioctl flags
  *
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 4d68c4e8a71d5f..cfa71dab28fdde 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -237,6 +237,7 @@
  *  - add FUSE_NOTIFY_INC_EPOCH
  *
  *  7.99
+ *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
  */
 
 #ifndef _LINUX_FUSE_H
@@ -445,6 +446,7 @@ struct fuse_file_lock {
  * FUSE_OVER_IO_URING: Indicate that client supports io-uring
  * FUSE_REQUEST_TIMEOUT: kernel supports timing out requests.
  *			 init_out.request_timeout contains the timeout (in secs)
+ * FUSE_IOMAP: Client supports iomap for regular file operations
  */
 #define FUSE_ASYNC_READ		(1 << 0)
 #define FUSE_POSIX_LOCKS	(1 << 1)
@@ -492,6 +494,7 @@ struct fuse_file_lock {
 #define FUSE_ALLOW_IDMAP	(1ULL << 40)
 #define FUSE_OVER_IO_URING	(1ULL << 41)
 #define FUSE_REQUEST_TIMEOUT	(1ULL << 42)
+#define FUSE_IOMAP		(1ULL << 43)
 
 /**
  * CUSE INIT request/reply flags
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index e4544dfc30d5c6..649a500614b80e 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2686,7 +2686,10 @@ _do_init(fuse_req_t req, const fuse_ino_t nodeid, const void *op_in,
 			se->conn.capable_ext |= FUSE_CAP_NO_EXPORT_SUPPORT;
 		if (inargflags & FUSE_OVER_IO_URING)
 			se->conn.capable_ext |= FUSE_CAP_OVER_IO_URING;
-
+		if (inargflags & FUSE_IOMAP)
+			se->conn.capable_ext |= FUSE_CAP_IOMAP;
+		/* Don't let anyone touch iomap until the end of the patchset. */
+		se->conn.capable_ext &= ~FUSE_CAP_IOMAP;
 	} else {
 		se->conn.max_readahead = 0;
 	}
@@ -2732,6 +2735,9 @@ _do_init(fuse_req_t req, const fuse_ino_t nodeid, const void *op_in,
 		       FUSE_CAP_READDIRPLUS_AUTO);
 	LL_SET_DEFAULT(1, FUSE_CAP_OVER_IO_URING);
 
+	/* servers need to opt-in to iomap explicitly */
+	LL_SET_DEFAULT(0, FUSE_CAP_IOMAP);
+
 	/* This could safely become default, but libfuse needs an API extension
 	 * to support it
 	 * LL_SET_DEFAULT(1, FUSE_CAP_SETXATTR_EXT);
@@ -2850,6 +2856,8 @@ _do_init(fuse_req_t req, const fuse_ino_t nodeid, const void *op_in,
 		outargflags |= FUSE_REQUEST_TIMEOUT;
 		outarg.request_timeout = se->conn.request_timeout;
 	}
+	if (se->conn.want_ext & FUSE_CAP_IOMAP)
+		outargflags |= FUSE_IOMAP;
 
 	if (inargflags & FUSE_INIT_EXT) {
 		outargflags |= FUSE_INIT_EXT;
@@ -2891,6 +2899,8 @@ _do_init(fuse_req_t req, const fuse_ino_t nodeid, const void *op_in,
 		if (se->conn.want_ext & FUSE_CAP_PASSTHROUGH)
 			fuse_log(FUSE_LOG_DEBUG, "   max_stack_depth=%u\n",
 				outarg.max_stack_depth);
+		if (se->conn.want_ext & FUSE_CAP_IOMAP)
+			fuse_log(FUSE_LOG_DEBUG, "   iomap=1\n");
 	}
 	if (arg->minor < 5)
 		outargsize = FUSE_COMPAT_INIT_OUT_SIZE;

[PATCH 03/18] libfuse: add fuse commands for iomap_begin and end

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Teach the low level API how to handle iomap begin and end commands that
we get from the kernel.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h   |   71 +++++++++++++++++++++++++++++++++
 include/fuse_kernel.h   |   40 ++++++++++++++++++
 include/fuse_lowlevel.h |   59 +++++++++++++++++++++++++++
 lib/fuse_lowlevel.c     |  102 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/fuse_versionscript  |    3 +
 5 files changed, 275 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index 9d53354de78868..12b951039f0a67 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1135,7 +1135,78 @@ bool fuse_get_feature_flag(struct fuse_conn_info *conn, uint64_t flag);
  */
 int fuse_convert_to_conn_want_ext(struct fuse_conn_info *conn);
 
+/**
+ * iomap operations.
+ * These APIs are introduced in version 399 (FUSE_MAKE_VERSION(3, 99)).
+ */
 
+/* mapping types; see corresponding IOMAP_TYPE_ */
+#define FUSE_IOMAP_TYPE_HOLE		(0)
+#define FUSE_IOMAP_TYPE_DELALLOC	(1)
+#define FUSE_IOMAP_TYPE_MAPPED		(2)
+#define FUSE_IOMAP_TYPE_UNWRITTEN	(3)
+#define FUSE_IOMAP_TYPE_INLINE		(4)
+
+/* fuse-specific mapping type indicating that writes use the read mapping */
+#define FUSE_IOMAP_TYPE_PURE_OVERWRITE	(255)
+
+#define FUSE_IOMAP_DEV_NULL		(0U)	/* null device cookie */
+
+/* mapping flags passed back from iomap_begin; see corresponding IOMAP_F_ */
+#define FUSE_IOMAP_F_NEW		(1U << 0)
+#define FUSE_IOMAP_F_DIRTY		(1U << 1)
+#define FUSE_IOMAP_F_SHARED		(1U << 2)
+#define FUSE_IOMAP_F_MERGED		(1U << 3)
+#define FUSE_IOMAP_F_BOUNDARY		(1U << 4)
+#define FUSE_IOMAP_F_ANON_WRITE		(1U << 5)
+#define FUSE_IOMAP_F_ATOMIC_BIO		(1U << 6)
+
+/* fuse-specific mapping flag asking for ->iomap_end call */
+#define FUSE_IOMAP_F_WANT_IOMAP_END	(1U << 7)
+
+/* mapping flags passed to iomap_end */
+#define FUSE_IOMAP_F_SIZE_CHANGED	(1U << 8)
+#define FUSE_IOMAP_F_STALE		(1U << 9)
+
+/* operation flags from iomap; see corresponding IOMAP_* */
+#define FUSE_IOMAP_OP_WRITE		(1U << 0)
+#define FUSE_IOMAP_OP_ZERO		(1U << 1)
+#define FUSE_IOMAP_OP_REPORT		(1U << 2)
+#define FUSE_IOMAP_OP_FAULT		(1U << 3)
+#define FUSE_IOMAP_OP_DIRECT		(1U << 4)
+#define FUSE_IOMAP_OP_NOWAIT		(1U << 5)
+#define FUSE_IOMAP_OP_OVERWRITE_ONLY	(1U << 6)
+#define FUSE_IOMAP_OP_UNSHARE		(1U << 7)
+#define FUSE_IOMAP_OP_DAX		(1U << 8)
+#define FUSE_IOMAP_OP_ATOMIC		(1U << 9)
+#define FUSE_IOMAP_OP_DONTCACHE		(1U << 10)
+
+/* pagecache writeback operation */
+#define FUSE_IOMAP_OP_WRITEBACK		(1U << 31)
+
+#define FUSE_IOMAP_NULL_ADDR		(-1ULL)	/* addr is not valid */
+
+struct fuse_file_iomap {
+	uint64_t addr;		/* disk offset of mapping, bytes */
+	uint64_t offset;	/* file offset of mapping, bytes */
+	uint64_t length;	/* length of mapping, bytes */
+	uint16_t type;		/* FUSE_IOMAP_TYPE_* */
+	uint16_t flags;		/* FUSE_IOMAP_F_* */
+	uint32_t dev;		/* device cookie */
+};
+
+static inline bool fuse_iomap_is_write(unsigned int opflags)
+{
+	return opflags & (FUSE_IOMAP_OP_WRITE | FUSE_IOMAP_OP_ZERO |
+			  FUSE_IOMAP_OP_UNSHARE | FUSE_IOMAP_OP_WRITEBACK);
+}
+
+static inline bool fuse_iomap_need_write_allocate(unsigned int opflags,
+					const struct fuse_file_iomap *map)
+{
+	return map->type == FUSE_IOMAP_TYPE_HOLE &&
+		!(opflags & FUSE_IOMAP_OP_ZERO);
+}
 
 /* ----------------------------------------------------------- *
  * Compatibility stuff					       *
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index cfa71dab28fdde..111aef43e17245 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -663,6 +663,9 @@ enum fuse_opcode {
 	FUSE_TMPFILE		= 51,
 	FUSE_STATX		= 52,
 
+	FUSE_IOMAP_BEGIN	= 4094,
+	FUSE_IOMAP_END		= 4095,
+
 	/* CUSE specific operations */
 	CUSE_INIT		= 4096,
 
@@ -1295,4 +1298,41 @@ struct fuse_uring_cmd_req {
 	uint8_t padding[6];
 };
 
+struct fuse_iomap_io {
+	uint64_t offset;	/* file offset of mapping, bytes */
+	uint64_t length;	/* length of mapping, bytes */
+	uint64_t addr;		/* disk offset of mapping, bytes */
+	uint16_t type;		/* FUSE_IOMAP_TYPE_* */
+	uint16_t flags;		/* FUSE_IOMAP_F_* */
+	uint32_t dev;		/* device cookie */
+};
+
+struct fuse_iomap_begin_in {
+	uint32_t opflags;	/* FUSE_IOMAP_OP_* */
+	uint32_t reserved;	/* zero */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+	uint64_t pos;		/* file position, in bytes */
+	uint64_t count;		/* operation length, in bytes */
+};
+
+struct fuse_iomap_begin_out {
+	/* read file data from here */
+	struct fuse_iomap_io	read;
+
+	/* write file data to here, if applicable */
+	struct fuse_iomap_io	write;
+};
+
+struct fuse_iomap_end_in {
+	uint32_t opflags;	/* FUSE_IOMAP_OP_* */
+	uint32_t reserved;	/* zero */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+	uint64_t pos;		/* file position, in bytes */
+	uint64_t count;		/* operation length, in bytes */
+	int64_t written;	/* bytes processed */
+
+	/* mapping that the kernel acted upon */
+	struct fuse_iomap_io	map;
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index a6cce014391aec..e2a81948811554 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1342,6 +1342,43 @@ struct fuse_lowlevel_ops {
 	 */
 	void (*statx)(fuse_req_t req, fuse_ino_t ino, int flags, int mask,
 		      struct fuse_file_info *fi);
+
+	/**
+	 * Fetch file I/O mappings to begin an operation
+	 *
+	 * Valid replies:
+	 *   fuse_reply_iomap_begin
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param nodeid the inode number
+	 * @param attr_ino inode number as told by fuse_attr::ino
+	 * @param pos position in file, in bytes
+	 * @param count length of operation, in bytes
+	 * @param opflags mask of FUSE_IOMAP_OP_ flags specifying operation
+	 */
+	void (*iomap_begin) (fuse_req_t req, fuse_ino_t nodeid,
+			     uint64_t attr_ino, off_t pos, uint64_t count,
+			     uint32_t opflags);
+
+	/**
+	 * Complete an iomap operation
+	 *
+	 * Valid replies:
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param nodeid the inode number
+	 * @param attr_ino inode number as told by fuse_attr::ino
+	 * @param pos position in file, in bytes
+	 * @param count length of operation, in bytes
+	 * @param written number of bytes processed, or a negative errno
+	 * @param opflags mask of FUSE_IOMAP_OP_ flags specifying operation
+	 * @param iomap file I/O mapping that was acted upon
+	 */
+	void (*iomap_end) (fuse_req_t req, fuse_ino_t nodeid, uint64_t attr_ino,
+			   off_t pos, uint64_t count, uint32_t opflags,
+			   ssize_t written, const struct fuse_file_iomap *iomap);
 };
 
 /**
@@ -1736,6 +1773,28 @@ int fuse_reply_lseek(fuse_req_t req, off_t off);
  */
 int fuse_reply_statx(fuse_req_t req, int flags, struct statx *statx, double attr_timeout);
 
+/**
+ * Set an iomap write mapping to be a pure overwrite of the read mapping.
+ * @param write mapping for file data writes
+ * @param read mapping for file data reads
+ */
+void fuse_iomap_pure_overwrite(struct fuse_file_iomap *write,
+			       const struct fuse_file_iomap *read);
+
+/**
+ * Reply with iomappings for an iomap_begin operation
+ *
+ * Possible requests:
+ *   iomap_begin
+ *
+ * @param req request handle
+ * @param read mapping for file data reads
+ * @param write mapping for file data writes
+ * @return zero for success, -errno for failure to send reply
+ */
+int fuse_reply_iomap_begin(fuse_req_t req, const struct fuse_file_iomap *read,
+			   const struct fuse_file_iomap *write);
+
 /* ----------------------------------------------------------- *
  * Notification						       *
  * ----------------------------------------------------------- */
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 649a500614b80e..89fcdb87db7dee 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2491,6 +2491,104 @@ static void do_statx(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 	_do_statx(req, nodeid, inarg, NULL);
 }
 
+void fuse_iomap_pure_overwrite(struct fuse_file_iomap *write,
+			       const struct fuse_file_iomap *read)
+{
+	write->addr = FUSE_IOMAP_NULL_ADDR;
+	write->offset = read->offset;
+	write->length = read->length;
+	write->type = FUSE_IOMAP_TYPE_PURE_OVERWRITE;
+	write->flags = 0;
+	write->dev = FUSE_IOMAP_DEV_NULL;
+}
+
+static inline void fuse_iomap_to_kernel(struct fuse_iomap_io *fmap,
+					const struct fuse_file_iomap *fimap)
+{
+	fmap->addr = fimap->addr;
+	fmap->offset = fimap->offset;
+	fmap->length = fimap->length;
+	fmap->type = fimap->type;
+	fmap->flags = fimap->flags;
+	fmap->dev = fimap->dev;
+}
+
+static inline void fuse_iomap_from_kernel(struct fuse_file_iomap *fimap,
+					  const struct fuse_iomap_io *fmap)
+{
+	fimap->addr = fmap->addr;
+	fimap->offset = fmap->offset;
+	fimap->length = fmap->length;
+	fimap->type = fmap->type;
+	fimap->flags = fmap->flags;
+	fimap->dev = fmap->dev;
+}
+
+int fuse_reply_iomap_begin(fuse_req_t req, const struct fuse_file_iomap *read,
+			   const struct fuse_file_iomap *write)
+{
+	struct fuse_iomap_begin_out arg = {
+		.write = {
+			.addr = FUSE_IOMAP_NULL_ADDR,
+			.offset = read->offset,
+			.length = read->length,
+			.type = FUSE_IOMAP_TYPE_PURE_OVERWRITE,
+			.flags = 0,
+			.dev = FUSE_IOMAP_DEV_NULL,
+		},
+	};
+
+	fuse_iomap_to_kernel(&arg.read, read);
+	if (write)
+		fuse_iomap_to_kernel(&arg.write, write);
+
+	return send_reply_ok(req, &arg, sizeof(arg));
+}
+
+static void _do_iomap_begin(fuse_req_t req, const fuse_ino_t nodeid,
+			    const void *op_in, const void *in_payload)
+{
+	const struct fuse_iomap_begin_in *arg = op_in;
+	(void)in_payload;
+	(void)nodeid;
+
+	if (req->se->op.iomap_begin)
+		req->se->op.iomap_begin(req, nodeid, arg->attr_ino, arg->pos,
+					arg->count, arg->opflags);
+	else
+		fuse_reply_err(req, ENOSYS);
+}
+
+static void do_iomap_begin(fuse_req_t req, const fuse_ino_t nodeid,
+			   const void *inarg)
+{
+	_do_iomap_begin(req, nodeid, inarg, NULL);
+}
+
+static void _do_iomap_end(fuse_req_t req, const fuse_ino_t nodeid,
+			    const void *op_in, const void *in_payload)
+{
+	const struct fuse_iomap_end_in *arg = op_in;
+	(void)in_payload;
+	(void)nodeid;
+
+	if (req->se->op.iomap_end) {
+		struct fuse_file_iomap fimap;
+
+		fuse_iomap_from_kernel(&fimap, &arg->map);
+		req->se->op.iomap_end(req, nodeid, arg->attr_ino, arg->pos,
+				      arg->count, arg->opflags, arg->written,
+				      &fimap);
+	} else
+		fuse_reply_err(req, ENOSYS);
+}
+
+static void do_iomap_end(fuse_req_t req, const fuse_ino_t nodeid,
+			   const void *inarg)
+{
+	_do_iomap_end(req, nodeid, inarg, NULL);
+}
+
 static bool want_flags_valid(uint64_t capable, uint64_t want)
 {
 	uint64_t unknown_flags = want & (~capable);
@@ -3390,6 +3488,8 @@ static struct {
 	[FUSE_COPY_FILE_RANGE] = { do_copy_file_range, "COPY_FILE_RANGE" },
 	[FUSE_LSEEK]	   = { do_lseek,       "LSEEK"	     },
 	[FUSE_STATX]	   = { do_statx,       "STATX"	     },
+	[FUSE_IOMAP_BEGIN] = { do_iomap_begin,	"IOMAP_BEGIN" },
+	[FUSE_IOMAP_END]   = { do_iomap_end,	"IOMAP_END" },
 	[CUSE_INIT]	   = { cuse_lowlevel_init, "CUSE_INIT"   },
 };
 
@@ -3445,6 +3545,8 @@ static struct {
 	[FUSE_COPY_FILE_RANGE]	= { _do_copy_file_range, "COPY_FILE_RANGE" },
 	[FUSE_LSEEK]		= { _do_lseek,		"LSEEK" },
 	[FUSE_STATX]		= { _do_statx,		"STATX" },
+	[FUSE_IOMAP_BEGIN]	= { _do_iomap_begin,	"IOMAP_BEGIN" },
+	[FUSE_IOMAP_END]	= { _do_iomap_end,	"IOMAP_END" },
 	[CUSE_INIT]		= { _cuse_lowlevel_init, "CUSE_INIT" },
 };
 
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 96a94e43f73909..eb4d2f350ec63c 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -219,6 +219,9 @@ FUSE_3.18 {
 } FUSE_3.17;
 
 FUSE_3.99 {
+	global:
+		fuse_iomap_pure_overwrite;
+		fuse_reply_iomap_begin;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 04/18] libfuse: add upper level iomap commands

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Teach the upper level fuse library about the iomap begin and end
operations, and connect it to the lower level.  This is needed for
fuse2fs to start using iomap.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h |   17 ++++++++++
 lib/fuse.c     |   98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+)


diff --git a/include/fuse.h b/include/fuse.h
index 209102651e9454..958034a539abe6 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -864,6 +864,23 @@ struct fuse_operations {
 	 */
 	int (*statx)(const char *path, int flags, int mask, struct statx *stxbuf,
 		     struct fuse_file_info *fi);
+
+	/**
+	 * Send a mapping to the kernel so that a file IO operation can run.
+	 */
+	int (*iomap_begin) (const char *path, uint64_t nodeid,
+			    uint64_t attr_ino, off_t pos_in,
+			    uint64_t length_in, uint32_t opflags_in,
+			    struct fuse_file_iomap *read_out,
+			    struct fuse_file_iomap *write_out);
+
+	/**
+	 * Respond to the outcome of a previous file mapping operation.
+	 */
+	int (*iomap_end) (const char *path, uint64_t nodeid, uint64_t attr_ino,
+			  off_t pos_in, uint64_t length_in,
+			  uint32_t opflags_in, ssize_t written_in,
+			  const struct fuse_file_iomap *iomap);
 };
 
 /** Extra context that may be needed by some filesystems
diff --git a/lib/fuse.c b/lib/fuse.c
index e997531f4433bb..eef0967f796ed6 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -2793,6 +2793,45 @@ int fuse_fs_chmod(struct fuse_fs *fs, const char *path, mode_t mode,
 	return fs->op.chmod(path, mode, fi);
 }
 
+static int fuse_fs_iomap_begin(struct fuse_fs *fs, const char *path,
+			       fuse_ino_t nodeid, uint64_t attr_ino, off_t pos,
+			       uint64_t count, uint32_t opflags,
+			       struct fuse_file_iomap *read,
+			       struct fuse_file_iomap *write)
+{
+	fuse_get_context()->private_data = fs->user_data;
+	if (!fs->op.iomap_begin)
+		return -ENOSYS;
+
+	if (fs->debug) {
+		fuse_log(FUSE_LOG_DEBUG,
+			 "iomap_begin[%s] nodeid %llu attr_ino %llu pos %llu count %llu opflags 0x%x\n",
+			 path, nodeid, attr_ino, pos, count, opflags);
+	}
+
+	return fs->op.iomap_begin(path, nodeid, attr_ino, pos, count, opflags,
+				  read, write);
+}
+
+static int fuse_fs_iomap_end(struct fuse_fs *fs, const char *path,
+			     fuse_ino_t nodeid, uint64_t attr_ino, off_t pos,
+			     uint64_t count, uint32_t opflags, ssize_t written,
+			     const struct fuse_file_iomap *iomap)
+{
+	fuse_get_context()->private_data = fs->user_data;
+	if (!fs->op.iomap_end)
+		return -ENOSYS;
+
+	if (fs->debug) {
+		fuse_log(FUSE_LOG_DEBUG,
+			 "iomap_end[%s] nodeid %llu attr_ino %llu pos %llu count %llu opflags 0x%x written %zd\n",
+			 path, nodeid, attr_ino, pos, count, opflags, written);
+	}
+
+	return fs->op.iomap_end(path, nodeid, attr_ino, pos, count, opflags,
+				written, iomap);
+}
+
 static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
 			     int valid, struct fuse_file_info *fi)
 {
@@ -4466,6 +4505,63 @@ static void fuse_lib_statx(fuse_req_t req, fuse_ino_t ino, int flags, int mask,
 }
 #endif
 
+static void fuse_lib_iomap_begin(fuse_req_t req, fuse_ino_t nodeid,
+				 uint64_t attr_ino, off_t pos, uint64_t count,
+				 uint32_t opflags)
+{
+	struct fuse *f = req_fuse_prepare(req);
+	struct fuse_file_iomap read = { };
+	struct fuse_file_iomap write = { };
+	struct fuse_intr_data d;
+	char *path;
+	int err;
+
+	err = get_path_nullok(f, nodeid, &path);
+	if (err) {
+		reply_err(req, err);
+		return;
+	}
+
+	fuse_prepare_interrupt(f, req, &d);
+	err = fuse_fs_iomap_begin(f->fs, path, nodeid, attr_ino, pos, count,
+				  opflags, &read, &write);
+	fuse_finish_interrupt(f, req, &d);
+	free_path(f, nodeid, path);
+	if (err) {
+		reply_err(req, err);
+		return;
+	}
+
+	if (write.length == 0)
+		fuse_iomap_pure_overwrite(&write, &read);
+
+	fuse_reply_iomap_begin(req, &read, &write);
+}
+
+static void fuse_lib_iomap_end(fuse_req_t req, fuse_ino_t nodeid,
+			       uint64_t attr_ino, off_t pos, uint64_t count,
+			       uint32_t opflags, ssize_t written,
+			       const struct fuse_file_iomap *iomap)
+{
+	struct fuse *f = req_fuse_prepare(req);
+	struct fuse_intr_data d;
+	char *path;
+	int err;
+
+	err = get_path_nullok(f, nodeid, &path);
+	if (err) {
+		reply_err(req, err);
+		return;
+	}
+
+	fuse_prepare_interrupt(f, req, &d);
+	err = fuse_fs_iomap_end(f->fs, path, nodeid, attr_ino, pos, count,
+				opflags, written, iomap);
+	fuse_finish_interrupt(f, req, &d);
+	free_path(f, nodeid, path);
+	reply_err(req, err);
+}
+
 static int clean_delay(struct fuse *f)
 {
 	/*
@@ -4567,6 +4663,8 @@ static struct fuse_lowlevel_ops fuse_path_ops = {
 #ifdef HAVE_STATX
 	.statx = fuse_lib_statx,
 #endif
+	.iomap_begin = fuse_lib_iomap_begin,
+	.iomap_end = fuse_lib_iomap_end,
 };
 
 int fuse_notify_poll(struct fuse_pollhandle *ph)

[PATCH 05/18] libfuse: add a lowlevel notification to add a new device to iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Plumb in the pieces needed to attach block devices to a fuse+iomap mount
for use with iomap operations.  This enables us to have filesystems
where the metadata could live somewhere else, but the actual file IO
goes to locally attached storage.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_kernel.h   |    7 +++++++
 include/fuse_lowlevel.h |   29 ++++++++++++++++++++++++++++
 lib/fuse_lowlevel.c     |   49 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/fuse_versionscript  |    2 ++
 4 files changed, 87 insertions(+)


diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 111aef43e17245..b544d0700165e8 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -1122,6 +1122,13 @@ struct fuse_notify_retrieve_in {
 	uint64_t	dummy4;
 };
 
+#define FUSE_BACKING_TYPE_MASK		(0xFF)
+#define FUSE_BACKING_TYPE_PASSTHROUGH	(0)
+#define FUSE_BACKING_TYPE_IOMAP		(1)
+#define FUSE_BACKING_MAX_TYPE		(FUSE_BACKING_TYPE_IOMAP)
+
+#define FUSE_BACKING_FLAGS_ALL		(FUSE_BACKING_TYPE_MASK)
+
 struct fuse_backing_map {
 	int32_t		fd;
 	uint32_t	flags;
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index e2a81948811554..45e3cf8c79b91d 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1998,6 +1998,35 @@ int fuse_lowlevel_notify_store(struct fuse_session *se, fuse_ino_t ino,
 int fuse_lowlevel_notify_retrieve(struct fuse_session *se, fuse_ino_t ino,
 				  size_t size, off_t offset, void *cookie);
 
+/**
+ * Attach an open file descriptor to a fuse+iomap mount.  Currently must be
+ * a block device.
+ *
+ * Added in FUSE protocol version 7.99. If the kernel does not support
+ * this (or a newer) version, the function will return -ENOSYS and do
+ * nothing.
+ *
+ * @param se the session object
+ * @param fd file descriptor of an open block device
+ * @param flags flags for the operation; none defined so far
+ * @return positive nonzero device id on success, or negative errno on failure
+ */
+int fuse_lowlevel_iomap_device_add(struct fuse_session *se, int fd,
+				   unsigned int flags);
+
+/**
+ * Detach an open file from a fuse+iomap mount.  Must be a device id returned
+ * by fuse_lowlevel_iomap_device_add.
+ *
+ * Added in FUSE protocol version 7.99. If the kernel does not support
+ * this (or a newer) version, the function will return -ENOSYS and do
+ * nothing.
+ *
+ * @param se the session object
+ * @param device_id device index as returned by fuse_lowlevel_iomap_device_add
+ * @return 0 on success, or negative errno on failure
+ */
+int fuse_lowlevel_iomap_device_remove(struct fuse_session *se, int device_id);
 
 /* ----------------------------------------------------------- *
  * Utility functions					       *
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 89fcdb87db7dee..a3cc5491ff6a24 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -580,6 +580,55 @@ int fuse_passthrough_close(fuse_req_t req, int backing_id)
 	return ret;
 }
 
+int fuse_lowlevel_iomap_device_add(struct fuse_session *se, int fd,
+				   unsigned int flags)
+{
+	struct fuse_backing_map map = {
+		.fd = fd,
+		.flags = FUSE_BACKING_TYPE_IOMAP |
+			(flags & ~FUSE_BACKING_TYPE_MASK),
+	};
+	int ret;
+
+	if (!(se->conn.want_ext & FUSE_CAP_IOMAP))
+		return -ENOSYS;
+
+	ret = ioctl(se->fd, FUSE_DEV_IOC_BACKING_OPEN, &map);
+	if (ret == 0) {
+		/* not supposed to happen */
+		ret = -1;
+		errno = ERANGE;
+	}
+	if (ret < 0) {
+		int err = errno;
+
+		fuse_log(FUSE_LOG_ERR, "fuse: iomap_device_add: %s\n",
+			 strerror(err));
+		return -err;
+	}
+
+	return ret;
+}
+
+int fuse_lowlevel_iomap_device_remove(struct fuse_session *se, int device_id)
+{
+	int ret;
+
+	if (!(se->conn.want_ext & FUSE_CAP_IOMAP))
+		return -ENOSYS;
+
+	ret = ioctl(se->fd, FUSE_DEV_IOC_BACKING_CLOSE, &device_id);
+	if (ret < 0) {
+		int err = errno;
+
+		fuse_log(FUSE_LOG_ERR, "fuse: iomap_device_remove: %s\n",
+			 strerror(errno));
+		return -err;
+	}
+
+	return ret;
+}
+
 int fuse_reply_open(fuse_req_t req, const struct fuse_file_info *f)
 {
 	struct fuse_open_out arg;
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index eb4d2f350ec63c..e796100c5ee414 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -222,6 +222,8 @@ FUSE_3.99 {
 	global:
 		fuse_iomap_pure_overwrite;
 		fuse_reply_iomap_begin;
+		fuse_lowlevel_iomap_device_add;
+		fuse_lowlevel_iomap_device_remove;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 06/18] libfuse: add upper-level iomap add device function

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Make it so that the upper level fuse library can add iomap devices too.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h         |   19 +++++++++++++++++++
 lib/fuse.c             |   16 ++++++++++++++++
 lib/fuse_versionscript |    2 ++
 3 files changed, 37 insertions(+)


diff --git a/include/fuse.h b/include/fuse.h
index 958034a539abe6..524b77b5d7bbd0 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -1381,6 +1381,25 @@ void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn,
 		struct fuse_config *cfg);
 void fuse_fs_destroy(struct fuse_fs *fs);
 
+/**
+ * Attach an open file descriptor to a fuse+iomap mount.  Currently must be
+ * a block device.
+ *
+ * @param fd file descriptor of an open block device
+ * @param flags flags for the operation; none defined so far
+ * @return positive nonzero device id on success, or negative errno on failure
+ */
+int fuse_fs_iomap_device_add(int fd, unsigned int flags);
+
+/**
+ * Detach an open file from a fuse+iomap mount.  Must be a device id returned
+ * by fuse_lowlevel_iomap_device_add.
+ *
+ * @param device_id device index as returned by fuse_lowlevel_iomap_device_add
+ * @return 0 on success, or negative errno on failure
+ */
+int fuse_fs_iomap_device_remove(int device_id);
+
 int fuse_notify_poll(struct fuse_pollhandle *ph);
 
 /**
diff --git a/lib/fuse.c b/lib/fuse.c
index eef0967f796ed6..632e935b8dff3e 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -2832,6 +2832,22 @@ static int fuse_fs_iomap_end(struct fuse_fs *fs, const char *path,
 				written, iomap);
 }
 
+int fuse_fs_iomap_device_add(int fd, unsigned int flags)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse_session *se = fuse_get_session(ctxt->fuse);
+
+	return fuse_lowlevel_iomap_device_add(se, fd, flags);
+}
+
+int fuse_fs_iomap_device_remove(int device_id)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse_session *se = fuse_get_session(ctxt->fuse);
+
+	return fuse_lowlevel_iomap_device_remove(se, device_id);
+}
+
 static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
 			     int valid, struct fuse_file_info *fi)
 {
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index e796100c5ee414..c42fae5d4a3c50 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -224,6 +224,8 @@ FUSE_3.99 {
 		fuse_reply_iomap_begin;
 		fuse_lowlevel_iomap_device_add;
 		fuse_lowlevel_iomap_device_remove;
+		fuse_fs_iomap_device_add;
+		fuse_fs_iomap_device_remove;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 07/18] libfuse: add iomap ioend low level handler

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Teach the low level library about the iomap ioend handler, which gets
called by the kernel when we finish a file write that isn't a pure
overwrite operation.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h   |   13 +++++++++++++
 include/fuse_kernel.h   |   11 +++++++++++
 include/fuse_lowlevel.h |   20 ++++++++++++++++++++
 lib/fuse_lowlevel.c     |   23 +++++++++++++++++++++++
 4 files changed, 67 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index 12b951039f0a67..c75428dae64e2f 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1208,6 +1208,19 @@ static inline bool fuse_iomap_need_write_allocate(unsigned int opflags,
 		!(opflags & FUSE_IOMAP_OP_ZERO);
 }
 
+/* out of place write extent */
+#define FUSE_IOMAP_IOEND_SHARED		(1U << 0)
+/* unwritten extent */
+#define FUSE_IOMAP_IOEND_UNWRITTEN	(1U << 1)
+/* don't merge into previous ioend */
+#define FUSE_IOMAP_IOEND_BOUNDARY	(1U << 2)
+/* is direct I/O */
+#define FUSE_IOMAP_IOEND_DIRECT		(1U << 3)
+/* is append ioend */
+#define FUSE_IOMAP_IOEND_APPEND		(1U << 4)
+/* is pagecache writeback */
+#define FUSE_IOMAP_IOEND_WRITEBACK	(1U << 5)
+
 /* ----------------------------------------------------------- *
  * Compatibility stuff					       *
  * ----------------------------------------------------------- */
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index b544d0700165e8..b349ede09e494f 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -663,6 +663,7 @@ enum fuse_opcode {
 	FUSE_TMPFILE		= 51,
 	FUSE_STATX		= 52,
 
+	FUSE_IOMAP_IOEND	= 4093,
 	FUSE_IOMAP_BEGIN	= 4094,
 	FUSE_IOMAP_END		= 4095,
 
@@ -1342,4 +1343,14 @@ struct fuse_iomap_end_in {
 	struct fuse_iomap_io	map;
 };
 
+struct fuse_iomap_ioend_in {
+	uint32_t ioendflags;	/* FUSE_IOMAP_IOEND_* */
+	int32_t error;		/* negative errno or 0 */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+	uint64_t pos;		/* file position, in bytes */
+	uint64_t new_addr;	/* disk offset of new mapping, in bytes */
+	uint32_t written;	/* bytes processed */
+	uint32_t reserved1;	/* zero */
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 45e3cf8c79b91d..ab274091f2248f 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1379,6 +1379,26 @@ struct fuse_lowlevel_ops {
 	void (*iomap_end) (fuse_req_t req, fuse_ino_t nodeid, uint64_t attr_ino,
 			   off_t pos, uint64_t count, uint32_t opflags,
 			   ssize_t written, const struct fuse_file_iomap *iomap);
+
+	/**
+	 * Complete an iomap IO operation
+	 *
+	 * Valid replies:
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param nodeid the inode number
+	 * @param attr_ino inode number as told by fuse_attr::ino
+	 * @param pos position in file, in bytes
+	 * @param written number of bytes processed, or a negative errno
+	 * @param ioendflags mask of FUSE_IOMAP_IOEND_ flags specifying operation
+	 * @param error errno code of what went wrong
+	 * @param new_addr disk address of new mapping, in bytes
+	 */
+	void (*iomap_ioend) (fuse_req_t req, fuse_ino_t nodeid,
+			     uint64_t attr_ino, off_t pos, size_t written,
+			     uint32_t ioendflags, int error,
+			     uint64_t new_addr);
 };
 
 /**
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index a3cc5491ff6a24..e8b78622b8f850 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2638,6 +2638,27 @@ static void do_iomap_end(fuse_req_t req, const fuse_ino_t nodeid,
 	_do_iomap_end(req, nodeid, inarg, NULL);
 }
 
+static void _do_iomap_ioend(fuse_req_t req, const fuse_ino_t nodeid,
+			    const void *op_in, const void *in_payload)
+{
+	const struct fuse_iomap_ioend_in *arg = op_in;
+	(void)in_payload;
+	(void)nodeid;
+
+	if (req->se->op.iomap_ioend)
+		req->se->op.iomap_ioend(req, nodeid, arg->attr_ino, arg->pos,
+					arg->written, arg->ioendflags,
+					arg->error, arg->new_addr);
+	else
+		fuse_reply_err(req, ENOSYS);
+}
+
+static void do_iomap_ioend(fuse_req_t req, const fuse_ino_t nodeid,
+			   const void *inarg)
+{
+	_do_iomap_ioend(req, nodeid, inarg, NULL);
+}
+
 static bool want_flags_valid(uint64_t capable, uint64_t want)
 {
 	uint64_t unknown_flags = want & (~capable);
@@ -3539,6 +3560,7 @@ static struct {
 	[FUSE_STATX]	   = { do_statx,       "STATX"	     },
 	[FUSE_IOMAP_BEGIN] = { do_iomap_begin,	"IOMAP_BEGIN" },
 	[FUSE_IOMAP_END]   = { do_iomap_end,	"IOMAP_END" },
+	[FUSE_IOMAP_IOEND] = { do_iomap_ioend,	"IOMAP_IOEND" },
 	[CUSE_INIT]	   = { cuse_lowlevel_init, "CUSE_INIT"   },
 };
 
@@ -3596,6 +3618,7 @@ static struct {
 	[FUSE_STATX]		= { _do_statx,		"STATX" },
 	[FUSE_IOMAP_BEGIN]	= { _do_iomap_begin,	"IOMAP_BEGIN" },
 	[FUSE_IOMAP_END]	= { _do_iomap_end,	"IOMAP_END" },
+	[FUSE_IOMAP_IOEND]	= { _do_iomap_ioend,	"IOMAP_IOEND" },
 	[CUSE_INIT]		= { _cuse_lowlevel_init, "CUSE_INIT" },
 };
 

[PATCH 08/18] libfuse: add upper level iomap ioend commands

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Teach the upper level fuse library about iomap ioend events, which
happen when a write that isn't a pure overwrite completes.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h |    8 ++++++++
 lib/fuse.c     |   45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)


diff --git a/include/fuse.h b/include/fuse.h
index 524b77b5d7bbd0..1357f4319bcc21 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -881,6 +881,14 @@ struct fuse_operations {
 			  off_t pos_in, uint64_t length_in,
 			  uint32_t opflags_in, ssize_t written_in,
 			  const struct fuse_file_iomap *iomap);
+
+	/**
+	 * Respond to the outcome of a file IO operation.
+	 */
+	int (*iomap_ioend) (const char *path, uint64_t nodeid,
+			    uint64_t attr_ino, off_t pos_in, size_t written_in,
+			    uint32_t ioendflags_in, int error_in,
+			    uint64_t new_addr_in);
 };
 
 /** Extra context that may be needed by some filesystems
diff --git a/lib/fuse.c b/lib/fuse.c
index 632e935b8dff3e..725ab615d456e3 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -2848,6 +2848,26 @@ int fuse_fs_iomap_device_remove(int device_id)
 	return fuse_lowlevel_iomap_device_remove(se, device_id);
 }
 
+static int fuse_fs_iomap_ioend(struct fuse_fs *fs, const char *path,
+			       uint64_t nodeid, uint64_t attr_ino, off_t pos,
+			       size_t written, uint32_t ioendflags, int error,
+			       uint64_t new_addr)
+{
+	fuse_get_context()->private_data = fs->user_data;
+	if (!fs->op.iomap_ioend)
+		return -ENOSYS;
+
+	if (fs->debug) {
+		fuse_log(FUSE_LOG_DEBUG,
+			 "iomap_ioend[%s] nodeid %llu attr_ino %llu pos %llu written %zu ioendflags 0x%x error %d\n",
+			 path, nodeid, attr_ino, pos, written, ioendflags,
+			 error);
+	}
+
+	return fs->op.iomap_ioend(path, nodeid, attr_ino, pos, written,
+				  ioendflags, error, new_addr);
+}
+
 static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
 			     int valid, struct fuse_file_info *fi)
 {
@@ -4578,6 +4598,30 @@ static void fuse_lib_iomap_end(fuse_req_t req, fuse_ino_t nodeid,
 	reply_err(req, err);
 }
 
+static void fuse_lib_iomap_ioend(fuse_req_t req, fuse_ino_t nodeid,
+				 uint64_t attr_ino, off_t pos, size_t written,
+				 uint32_t ioendflags, int error,
+				 uint64_t new_addr)
+{
+	struct fuse *f = req_fuse_prepare(req);
+	struct fuse_intr_data d;
+	char *path;
+	int err;
+
+	err = get_path_nullok(f, nodeid, &path);
+	if (err) {
+		reply_err(req, err);
+		return;
+	}
+
+	fuse_prepare_interrupt(f, req, &d);
+	err = fuse_fs_iomap_ioend(f->fs, path, nodeid, attr_ino, pos, written,
+				  ioendflags, error, new_addr);
+	fuse_finish_interrupt(f, req, &d);
+	free_path(f, nodeid, path);
+	reply_err(req, err);
+}
+
 static int clean_delay(struct fuse *f)
 {
 	/*
@@ -4681,6 +4725,7 @@ static struct fuse_lowlevel_ops fuse_path_ops = {
 #endif
 	.iomap_begin = fuse_lib_iomap_begin,
 	.iomap_end = fuse_lib_iomap_end,
+	.iomap_ioend = fuse_lib_iomap_ioend,
 };
 
 int fuse_notify_poll(struct fuse_pollhandle *ph)

[PATCH 09/18] libfuse: add a reply function to send FUSE_ATTR_* to the kernel

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create new fuse_reply_{attr,create,entry}_iflags functions so that we
can send FUSE_ATTR_* flags to the kernel when instantiating an inode.
Servers are expected to send FUSE_IFLAG_* values, which will be
translated into what the kernel can understand.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h   |    3 ++
 include/fuse_lowlevel.h |   83 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/fuse_lowlevel.c     |   64 ++++++++++++++++++++++++++++--------
 lib/fuse_versionscript  |    4 ++
 4 files changed, 139 insertions(+), 15 deletions(-)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index c75428dae64e2f..faf0bc57bcdbe6 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1221,6 +1221,9 @@ static inline bool fuse_iomap_need_write_allocate(unsigned int opflags,
 /* is pagecache writeback */
 #define FUSE_IOMAP_IOEND_WRITEBACK	(1U << 5)
 
+/* enable fsdax */
+#define FUSE_IFLAG_DAX			(1U << 0)
+
 /* ----------------------------------------------------------- *
  * Compatibility stuff					       *
  * ----------------------------------------------------------- */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index ab274091f2248f..dfe28d33d8d0b8 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -243,6 +243,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_entry
+	 *   fuse_reply_entry_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -302,6 +303,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_attr
+	 *   fuse_reply_attr_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -337,6 +339,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_attr
+	 *   fuse_reply_attr_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -368,6 +371,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_entry
+	 *   fuse_reply_entry_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -384,6 +388,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_entry
+	 *   fuse_reply_entry_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -433,6 +438,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_entry
+	 *   fuse_reply_entry_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -481,6 +487,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_entry
+	 *   fuse_reply_entry_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -972,6 +979,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_create
+	 *   fuse_reply_create_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -1317,6 +1325,7 @@ struct fuse_lowlevel_ops {
 	 *
 	 * Valid replies:
 	 *   fuse_reply_create
+	 *   fuse_reply_create_iflags
 	 *   fuse_reply_err
 	 *
 	 * @param req request handle
@@ -1451,6 +1460,23 @@ void fuse_reply_none(fuse_req_t req);
  */
 int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e);
 
+/**
+ * Reply with a directory entry and FUSE_IFLAG_*
+ *
+ * Possible requests:
+ *   lookup, mknod, mkdir, symlink, link
+ *
+ * Side effects:
+ *   increments the lookup count on success
+ *
+ * @param req request handle
+ * @param e the entry parameters
+ * @param iflags	FUSE_IFLAG_*
+ * @return zero for success, -errno for failure to send reply
+ */
+int fuse_reply_entry_iflags(fuse_req_t req, const struct fuse_entry_param *e,
+			    unsigned int iflags);
+
 /**
  * Reply with a directory entry and open parameters
  *
@@ -1472,6 +1498,29 @@ int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e);
 int fuse_reply_create(fuse_req_t req, const struct fuse_entry_param *e,
 		      const struct fuse_file_info *fi);
 
+/**
+ * Reply with a directory entry, open parameters and FUSE_IFLAG_*
+ *
+ * currently the following members of 'fi' are used:
+ *   fh, direct_io, keep_cache, cache_readdir, nonseekable, noflush,
+ *   parallel_direct_writes
+ *
+ * Possible requests:
+ *   create
+ *
+ * Side effects:
+ *   increments the lookup count on success
+ *
+ * @param req request handle
+ * @param e the entry parameters
+ * @param iflags	FUSE_IFLAG_*
+ * @param fi file information
+ * @return zero for success, -errno for failure to send reply
+ */
+int fuse_reply_create_iflags(fuse_req_t req, const struct fuse_entry_param *e,
+			     unsigned int iflags,
+			     const struct fuse_file_info *fi);
+
 /**
  * Reply with attributes
  *
@@ -1486,6 +1535,21 @@ int fuse_reply_create(fuse_req_t req, const struct fuse_entry_param *e,
 int fuse_reply_attr(fuse_req_t req, const struct stat *attr,
 		    double attr_timeout);
 
+/**
+ * Reply with attributes and FUSE_IFLAG_* flags
+ *
+ * Possible requests:
+ *   getattr, setattr
+ *
+ * @param req request handle
+ * @param attr the attributes
+ * @param attr_timeout	validity timeout (in seconds) for the attributes
+ * @param iflags	set of FUSE_IFLAG_* flags
+ * @return zero for success, -errno for failure to send reply
+ */
+int fuse_reply_attr_iflags(fuse_req_t req, const struct stat *attr,
+			   unsigned int iflags, double attr_timeout);
+
 /**
  * Reply with the contents of a symbolic link
  *
@@ -1713,6 +1777,25 @@ size_t fuse_add_direntry_plus(fuse_req_t req, char *buf, size_t bufsize,
 			      const char *name,
 			      const struct fuse_entry_param *e, off_t off);
 
+/**
+ * Add a directory entry and FUSE_IFLAG_* to the buffer with the attributes
+ *
+ * See documentation of `fuse_add_direntry_plus()` for more details.
+ *
+ * @param req request handle
+ * @param buf the point where the new entry will be added to the buffer
+ * @param bufsize remaining size of the buffer
+ * @param name the name of the entry
+ * @param iflags	FUSE_IFLAG_*
+ * @param e the directory entry
+ * @param off the offset of the next entry
+ * @return the space needed for the entry
+ */
+size_t fuse_add_direntry_plus_iflags(fuse_req_t req, char *buf, size_t bufsize,
+				     const char *name, unsigned int iflags,
+				     const struct fuse_entry_param *e,
+				     off_t off);
+
 /**
  * Reply to ask for data fetch and output buffer preparation.  ioctl
  * will be retried with the specified input data fetched and output
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index e8b78622b8f850..bddc161412f33e 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -102,7 +102,8 @@ static void trace_request_reply(uint64_t unique, unsigned int len,
 }
 #endif
 
-static void convert_stat(const struct stat *stbuf, struct fuse_attr *attr)
+static void convert_stat(const struct stat *stbuf, struct fuse_attr *attr,
+			 unsigned int iflags)
 {
 	attr->ino	= stbuf->st_ino;
 	attr->mode	= stbuf->st_mode;
@@ -119,6 +120,10 @@ static void convert_stat(const struct stat *stbuf, struct fuse_attr *attr)
 	attr->atimensec = ST_ATIM_NSEC(stbuf);
 	attr->mtimensec = ST_MTIM_NSEC(stbuf);
 	attr->ctimensec = ST_CTIM_NSEC(stbuf);
+
+	attr->flags	= 0;
+	if (iflags & FUSE_IFLAG_DAX)
+		attr->flags |= FUSE_ATTR_DAX;
 }
 
 static void convert_attr(const struct fuse_setattr_in *attr, struct stat *stbuf)
@@ -438,7 +443,8 @@ static unsigned int calc_timeout_nsec(double t)
 }
 
 static void fill_entry(struct fuse_entry_out *arg,
-		       const struct fuse_entry_param *e)
+		       const struct fuse_entry_param *e,
+		       unsigned int iflags)
 {
 	arg->nodeid = e->ino;
 	arg->generation = e->generation;
@@ -446,14 +452,15 @@ static void fill_entry(struct fuse_entry_out *arg,
 	arg->entry_valid_nsec = calc_timeout_nsec(e->entry_timeout);
 	arg->attr_valid = calc_timeout_sec(e->attr_timeout);
 	arg->attr_valid_nsec = calc_timeout_nsec(e->attr_timeout);
-	convert_stat(&e->attr, &arg->attr);
+	convert_stat(&e->attr, &arg->attr, iflags);
 }
 
 /* `buf` is allowed to be empty so that the proper size may be
    allocated by the caller */
-size_t fuse_add_direntry_plus(fuse_req_t req, char *buf, size_t bufsize,
-			      const char *name,
-			      const struct fuse_entry_param *e, off_t off)
+size_t fuse_add_direntry_plus_iflags(fuse_req_t req, char *buf, size_t bufsize,
+				     const char *name, unsigned int iflags,
+				     const struct fuse_entry_param *e,
+				     off_t off)
 {
 	(void)req;
 	size_t namelen;
@@ -468,7 +475,7 @@ size_t fuse_add_direntry_plus(fuse_req_t req, char *buf, size_t bufsize,
 
 	struct fuse_direntplus *dp = (struct fuse_direntplus *) buf;
 	memset(&dp->entry_out, 0, sizeof(dp->entry_out));
-	fill_entry(&dp->entry_out, e);
+	fill_entry(&dp->entry_out, e, iflags);
 
 	struct fuse_dirent *dirent = &dp->dirent;
 	dirent->ino = e->attr.st_ino;
@@ -481,6 +488,14 @@ size_t fuse_add_direntry_plus(fuse_req_t req, char *buf, size_t bufsize,
 	return entlen_padded;
 }
 
+size_t fuse_add_direntry_plus(fuse_req_t req, char *buf, size_t bufsize,
+			      const char *name,
+			      const struct fuse_entry_param *e, off_t off)
+{
+	return fuse_add_direntry_plus_iflags(req, buf, bufsize, name, 0, e,
+					     off);
+}
+
 static void fill_open(struct fuse_open_out *arg,
 		      const struct fuse_file_info *f)
 {
@@ -503,7 +518,8 @@ static void fill_open(struct fuse_open_out *arg,
 		arg->open_flags |= FOPEN_PARALLEL_DIRECT_WRITES;
 }
 
-int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e)
+int fuse_reply_entry_iflags(fuse_req_t req, const struct fuse_entry_param *e,
+			    unsigned int iflags)
 {
 	struct fuse_entry_out arg;
 	size_t size = req->se->conn.proto_minor < 9 ?
@@ -515,12 +531,18 @@ int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e)
 		return fuse_reply_err(req, ENOENT);
 
 	memset(&arg, 0, sizeof(arg));
-	fill_entry(&arg, e);
+	fill_entry(&arg, e, iflags);
 	return send_reply_ok(req, &arg, size);
 }
 
-int fuse_reply_create(fuse_req_t req, const struct fuse_entry_param *e,
-		      const struct fuse_file_info *f)
+int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e)
+{
+	return fuse_reply_entry_iflags(req, e, 0);
+}
+
+int fuse_reply_create_iflags(fuse_req_t req, const struct fuse_entry_param *e,
+			     unsigned int iflags,
+			     const struct fuse_file_info *f)
 {
 	alignas(uint64_t) char buf[sizeof(struct fuse_entry_out) + sizeof(struct fuse_open_out)];
 	size_t entrysize = req->se->conn.proto_minor < 9 ?
@@ -529,14 +551,20 @@ int fuse_reply_create(fuse_req_t req, const struct fuse_entry_param *e,
 	struct fuse_open_out *oarg = (struct fuse_open_out *) (buf + entrysize);
 
 	memset(buf, 0, sizeof(buf));
-	fill_entry(earg, e);
+	fill_entry(earg, e, iflags);
 	fill_open(oarg, f);
 	return send_reply_ok(req, buf,
 			     entrysize + sizeof(struct fuse_open_out));
 }
 
-int fuse_reply_attr(fuse_req_t req, const struct stat *attr,
-		    double attr_timeout)
+int fuse_reply_create(fuse_req_t req, const struct fuse_entry_param *e,
+		      const struct fuse_file_info *f)
+{
+	return fuse_reply_create_iflags(req, e, 0, f);
+}
+
+int fuse_reply_attr_iflags(fuse_req_t req, const struct stat *attr,
+			   unsigned int iflags, double attr_timeout)
 {
 	struct fuse_attr_out arg;
 	size_t size = req->se->conn.proto_minor < 9 ?
@@ -545,11 +573,17 @@ int fuse_reply_attr(fuse_req_t req, const struct stat *attr,
 	memset(&arg, 0, sizeof(arg));
 	arg.attr_valid = calc_timeout_sec(attr_timeout);
 	arg.attr_valid_nsec = calc_timeout_nsec(attr_timeout);
-	convert_stat(attr, &arg.attr);
+	convert_stat(attr, &arg.attr, iflags);
 
 	return send_reply_ok(req, &arg, size);
 }
 
+int fuse_reply_attr(fuse_req_t req, const struct stat *attr,
+		    double attr_timeout)
+{
+	return fuse_reply_attr_iflags(req, attr, 0, attr_timeout);
+}
+
 int fuse_reply_readlink(fuse_req_t req, const char *linkname)
 {
 	return send_reply_ok(req, linkname, strlen(linkname));
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index c42fae5d4a3c50..29a000fff16104 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -226,6 +226,10 @@ FUSE_3.99 {
 		fuse_lowlevel_iomap_device_remove;
 		fuse_fs_iomap_device_add;
 		fuse_fs_iomap_device_remove;
+		fuse_reply_attr_iflags;
+		fuse_reply_create_iflags;
+		fuse_reply_entry_iflags;
+		fuse_add_direntry_plus_iflags;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 10/18] libfuse: connect high level fuse library to fuse_reply_attr_iflags

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create a new ->getattr_iflags function so that iomap filesystems can set
the appropriate in-kernel inode flags on instantiation.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h |    7 ++
 lib/fuse.c     |  191 ++++++++++++++++++++++++++++++++++++++++++--------------
 2 files changed, 151 insertions(+), 47 deletions(-)


diff --git a/include/fuse.h b/include/fuse.h
index 1357f4319bcc21..7256f43fd5c39a 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -889,6 +889,13 @@ struct fuse_operations {
 			    uint64_t attr_ino, off_t pos_in, size_t written_in,
 			    uint32_t ioendflags_in, int error_in,
 			    uint64_t new_addr_in);
+
+	/**
+	 * Get file attributes and FUSE_IFLAG_* flags.  Otherwise the same as
+	 * getattr.
+	 */
+	int (*getattr_iflags) (const char *path, struct stat *buf,
+			       unsigned int *iflags, struct fuse_file_info *fi);
 };
 
 /** Extra context that may be needed by some filesystems
diff --git a/lib/fuse.c b/lib/fuse.c
index 725ab615d456e3..6b211084e2175a 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -123,6 +123,7 @@ struct fuse {
 	struct list_head partial_slabs;
 	struct list_head full_slabs;
 	pthread_t prune_thread;
+	bool want_iflags;
 };
 
 struct lock {
@@ -144,6 +145,7 @@ struct node {
 	char *name;
 	uint64_t nlookup;
 	int open_count;
+	unsigned int iflags;
 	struct timespec stat_updated;
 	struct timespec mtime;
 	off_t size;
@@ -1628,6 +1630,24 @@ int fuse_fs_getattr(struct fuse_fs *fs, const char *path, struct stat *buf,
 	return fs->op.getattr(path, buf, fi);
 }
 
+static int fuse_fs_getattr_iflags(struct fuse_fs *fs, const char *path,
+				  struct stat *buf, unsigned int *iflags,
+				  struct fuse_file_info *fi)
+{
+	fuse_get_context()->private_data = fs->user_data;
+	if (!fs->op.getattr_iflags)
+		return -ENOSYS;
+
+	if (fs->debug) {
+		char buf[10];
+
+		fuse_log(FUSE_LOG_DEBUG, "getattr_iflags[%s] %s\n",
+			file_info_string(fi, buf, sizeof(buf)),
+			path);
+	}
+	return fs->op.getattr_iflags(path, buf, iflags, fi);
+}
+
 int fuse_fs_rename(struct fuse_fs *fs, const char *oldpath,
 		   const char *newpath, unsigned int flags)
 {
@@ -2473,7 +2493,7 @@ static void update_stat(struct node *node, const struct stat *stbuf)
 }
 
 static int do_lookup(struct fuse *f, fuse_ino_t nodeid, const char *name,
-		     struct fuse_entry_param *e)
+		     struct fuse_entry_param *e, unsigned int *iflags)
 {
 	struct node *node;
 
@@ -2491,25 +2511,64 @@ static int do_lookup(struct fuse *f, fuse_ino_t nodeid, const char *name,
 		pthread_mutex_unlock(&f->lock);
 	}
 	set_stat(f, e->ino, &e->attr);
+	*iflags = node->iflags;
 	return 0;
 }
 
+static int lookup_and_update(struct fuse *f, fuse_ino_t nodeid,
+			     const char *name, struct fuse_entry_param *e,
+			     unsigned int iflags)
+{
+	struct node *node;
+
+	node = find_node(f, nodeid, name);
+	if (node == NULL)
+		return -ENOMEM;
+
+	e->ino = node->nodeid;
+	e->generation = node->generation;
+	e->entry_timeout = f->conf.entry_timeout;
+	e->attr_timeout = f->conf.attr_timeout;
+	if (f->conf.auto_cache) {
+		pthread_mutex_lock(&f->lock);
+		update_stat(node, &e->attr);
+		pthread_mutex_unlock(&f->lock);
+	}
+	set_stat(f, e->ino, &e->attr);
+	node->iflags = iflags;
+	return 0;
+}
+
+static int getattr(struct fuse *f, const char *path, struct stat *buf,
+		   unsigned int *iflags, struct fuse_file_info *fi)
+{
+	if (f->want_iflags)
+		return fuse_fs_getattr_iflags(f->fs, path, buf, iflags, fi);
+	return fuse_fs_getattr(f->fs, path, buf, fi);
+}
+
 static int lookup_path(struct fuse *f, fuse_ino_t nodeid,
 		       const char *name, const char *path,
-		       struct fuse_entry_param *e, struct fuse_file_info *fi)
+		       struct fuse_entry_param *e, unsigned int *iflags,
+		       struct fuse_file_info *fi)
 {
 	int res;
 
 	memset(e, 0, sizeof(struct fuse_entry_param));
-	res = fuse_fs_getattr(f->fs, path, &e->attr, fi);
-	if (res == 0) {
-		res = do_lookup(f, nodeid, name, e);
-		if (res == 0 && f->conf.debug) {
-			fuse_log(FUSE_LOG_DEBUG, "   NODEID: %llu\n",
-				(unsigned long long) e->ino);
-		}
-	}
-	return res;
+	*iflags = 0;
+	res = getattr(f, path, &e->attr, iflags, fi);
+	if (res)
+		return res;
+
+	res = lookup_and_update(f, nodeid, name, e, *iflags);
+	if (res)
+		return res;
+
+	if (f->conf.debug)
+		fuse_log(FUSE_LOG_DEBUG, "   NODEID: %llu iflags 0x%x\n",
+			(unsigned long long) e->ino, *iflags);
+
+	return 0;
 }
 
 static struct fuse_context_i *fuse_get_context_internal(void)
@@ -2593,11 +2652,14 @@ static inline void reply_err(fuse_req_t req, int err)
 }
 
 static void reply_entry(fuse_req_t req, const struct fuse_entry_param *e,
-			int err)
+			unsigned int iflags, int err)
 {
 	if (!err) {
 		struct fuse *f = req_fuse(req);
-		if (fuse_reply_entry(req, e) == -ENOENT) {
+		int entry_res;
+
+		entry_res = fuse_reply_entry_iflags(req, e, iflags);
+		if (entry_res == -ENOENT) {
 			/* Skip forget for negative result */
 			if  (e->ino != 0)
 				forget_node(f, e->ino, 1);
@@ -2638,6 +2700,9 @@ static void fuse_lib_init(void *data, struct fuse_conn_info *conn)
 		/* Disable the receiving and processing of FUSE_INTERRUPT requests */
 		conn->no_interrupt = 1;
 	}
+
+	if (conn->want_ext & FUSE_CAP_IOMAP)
+		f->want_iflags = true;
 }
 
 void fuse_fs_destroy(struct fuse_fs *fs)
@@ -2661,6 +2726,7 @@ static void fuse_lib_lookup(fuse_req_t req, fuse_ino_t parent,
 	struct fuse *f = req_fuse_prepare(req);
 	struct fuse_entry_param e;
 	char *path;
+	unsigned int iflags = 0;
 	int err;
 	struct node *dot = NULL;
 
@@ -2675,7 +2741,7 @@ static void fuse_lib_lookup(fuse_req_t req, fuse_ino_t parent,
 				dot = get_node_nocheck(f, parent);
 				if (dot == NULL) {
 					pthread_mutex_unlock(&f->lock);
-					reply_entry(req, &e, -ESTALE);
+					reply_entry(req, &e, -ESTALE, 0);
 					return;
 				}
 				dot->refctr++;
@@ -2695,7 +2761,7 @@ static void fuse_lib_lookup(fuse_req_t req, fuse_ino_t parent,
 		if (f->conf.debug)
 			fuse_log(FUSE_LOG_DEBUG, "LOOKUP %s\n", path);
 		fuse_prepare_interrupt(f, req, &d);
-		err = lookup_path(f, parent, name, path, &e, NULL);
+		err = lookup_path(f, parent, name, path, &e, &iflags, NULL);
 		if (err == -ENOENT && f->conf.negative_timeout != 0.0) {
 			e.ino = 0;
 			e.entry_timeout = f->conf.negative_timeout;
@@ -2709,7 +2775,7 @@ static void fuse_lib_lookup(fuse_req_t req, fuse_ino_t parent,
 		unref_node(f, dot);
 		pthread_mutex_unlock(&f->lock);
 	}
-	reply_entry(req, &e, err);
+	reply_entry(req, &e, iflags, err);
 }
 
 static void do_forget(struct fuse *f, fuse_ino_t ino, uint64_t nlookup)
@@ -2745,6 +2811,7 @@ static void fuse_lib_getattr(fuse_req_t req, fuse_ino_t ino,
 	struct fuse *f = req_fuse_prepare(req);
 	struct stat buf;
 	char *path;
+	unsigned int iflags = 0;
 	int err;
 
 	memset(&buf, 0, sizeof(buf));
@@ -2756,7 +2823,7 @@ static void fuse_lib_getattr(fuse_req_t req, fuse_ino_t ino,
 	if (!err) {
 		struct fuse_intr_data d;
 		fuse_prepare_interrupt(f, req, &d);
-		err = fuse_fs_getattr(f->fs, path, &buf, fi);
+		err = getattr(f, path, &buf, &iflags, fi);
 		fuse_finish_interrupt(f, req, &d);
 		free_path(f, ino, path);
 	}
@@ -2769,9 +2836,11 @@ static void fuse_lib_getattr(fuse_req_t req, fuse_ino_t ino,
 			buf.st_nlink--;
 		if (f->conf.auto_cache)
 			update_stat(node, &buf);
+		node->iflags = iflags;
 		pthread_mutex_unlock(&f->lock);
 		set_stat(f, ino, &buf);
-		fuse_reply_attr(req, &buf, f->conf.attr_timeout);
+		fuse_reply_attr_iflags(req, &buf, iflags,
+				       f->conf.attr_timeout);
 	} else
 		reply_err(req, err);
 }
@@ -2874,6 +2943,7 @@ static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
 	struct fuse *f = req_fuse_prepare(req);
 	struct stat buf;
 	char *path;
+	unsigned int iflags = 0;
 	int err;
 
 	memset(&buf, 0, sizeof(buf));
@@ -2932,19 +3002,23 @@ static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
 			err = fuse_fs_utimens(f->fs, path, tv, fi);
 		}
 		if (!err) {
-			err = fuse_fs_getattr(f->fs, path, &buf, fi);
+			err = getattr(f, path, &buf, &iflags, fi);
 		}
 		fuse_finish_interrupt(f, req, &d);
 		free_path(f, ino, path);
 	}
 	if (!err) {
-		if (f->conf.auto_cache) {
-			pthread_mutex_lock(&f->lock);
-			update_stat(get_node(f, ino), &buf);
-			pthread_mutex_unlock(&f->lock);
-		}
+		struct node *node;
+
+		pthread_mutex_lock(&f->lock);
+		node = get_node(f, ino);
+		if (f->conf.auto_cache)
+			update_stat(node, &buf);
+		node->iflags = iflags;
+		pthread_mutex_unlock(&f->lock);
 		set_stat(f, ino, &buf);
-		fuse_reply_attr(req, &buf, f->conf.attr_timeout);
+		fuse_reply_attr_iflags(req, &buf, iflags,
+				       f->conf.attr_timeout);
 	} else
 		reply_err(req, err);
 }
@@ -2995,6 +3069,7 @@ static void fuse_lib_mknod(fuse_req_t req, fuse_ino_t parent, const char *name,
 	struct fuse *f = req_fuse_prepare(req);
 	struct fuse_entry_param e;
 	char *path;
+	unsigned int iflags = 0;
 	int err;
 
 	err = get_path_name(f, parent, name, &path);
@@ -3011,7 +3086,7 @@ static void fuse_lib_mknod(fuse_req_t req, fuse_ino_t parent, const char *name,
 			err = fuse_fs_create(f->fs, path, mode, &fi);
 			if (!err) {
 				err = lookup_path(f, parent, name, path, &e,
-						  &fi);
+						  &iflags, &fi);
 				fuse_fs_release(f->fs, path, &fi);
 			}
 		}
@@ -3019,12 +3094,12 @@ static void fuse_lib_mknod(fuse_req_t req, fuse_ino_t parent, const char *name,
 			err = fuse_fs_mknod(f->fs, path, mode, rdev);
 			if (!err)
 				err = lookup_path(f, parent, name, path, &e,
-						  NULL);
+						  &iflags, NULL);
 		}
 		fuse_finish_interrupt(f, req, &d);
 		free_path(f, parent, path);
 	}
-	reply_entry(req, &e, err);
+	reply_entry(req, &e, iflags, err);
 }
 
 static void fuse_lib_mkdir(fuse_req_t req, fuse_ino_t parent, const char *name,
@@ -3033,6 +3108,7 @@ static void fuse_lib_mkdir(fuse_req_t req, fuse_ino_t parent, const char *name,
 	struct fuse *f = req_fuse_prepare(req);
 	struct fuse_entry_param e;
 	char *path;
+	unsigned int iflags = 0;
 	int err;
 
 	err = get_path_name(f, parent, name, &path);
@@ -3042,11 +3118,12 @@ static void fuse_lib_mkdir(fuse_req_t req, fuse_ino_t parent, const char *name,
 		fuse_prepare_interrupt(f, req, &d);
 		err = fuse_fs_mkdir(f->fs, path, mode);
 		if (!err)
-			err = lookup_path(f, parent, name, path, &e, NULL);
+			err = lookup_path(f, parent, name, path, &e, &iflags,
+					  NULL);
 		fuse_finish_interrupt(f, req, &d);
 		free_path(f, parent, path);
 	}
-	reply_entry(req, &e, err);
+	reply_entry(req, &e, iflags, err);
 }
 
 static void fuse_lib_unlink(fuse_req_t req, fuse_ino_t parent,
@@ -3116,6 +3193,7 @@ static void fuse_lib_symlink(fuse_req_t req, const char *linkname,
 	struct fuse *f = req_fuse_prepare(req);
 	struct fuse_entry_param e;
 	char *path;
+	unsigned int iflags = 0;
 	int err;
 
 	err = get_path_name(f, parent, name, &path);
@@ -3125,11 +3203,12 @@ static void fuse_lib_symlink(fuse_req_t req, const char *linkname,
 		fuse_prepare_interrupt(f, req, &d);
 		err = fuse_fs_symlink(f->fs, linkname, path);
 		if (!err)
-			err = lookup_path(f, parent, name, path, &e, NULL);
+			err = lookup_path(f, parent, name, path, &e, &iflags,
+					  NULL);
 		fuse_finish_interrupt(f, req, &d);
 		free_path(f, parent, path);
 	}
-	reply_entry(req, &e, err);
+	reply_entry(req, &e, iflags, err);
 }
 
 static void fuse_lib_rename(fuse_req_t req, fuse_ino_t olddir,
@@ -3177,6 +3256,7 @@ static void fuse_lib_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t newparent,
 	struct fuse_entry_param e;
 	char *oldpath;
 	char *newpath;
+	unsigned int iflags = 0;
 	int err;
 
 	err = get_path2(f, ino, NULL, newparent, newname,
@@ -3188,11 +3268,11 @@ static void fuse_lib_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t newparent,
 		err = fuse_fs_link(f->fs, oldpath, newpath);
 		if (!err)
 			err = lookup_path(f, newparent, newname, newpath,
-					  &e, NULL);
+					  &e, &iflags, NULL);
 		fuse_finish_interrupt(f, req, &d);
 		free_path2(f, ino, newparent, NULL, NULL, oldpath, newpath);
 	}
-	reply_entry(req, &e, err);
+	reply_entry(req, &e, iflags, err);
 }
 
 static void fuse_do_release(struct fuse *f, fuse_ino_t ino, const char *path,
@@ -3235,6 +3315,7 @@ static void fuse_lib_create(fuse_req_t req, fuse_ino_t parent,
 	struct fuse_intr_data d;
 	struct fuse_entry_param e;
 	char *path;
+	unsigned int iflags;
 	int err;
 
 	err = get_path_name(f, parent, name, &path);
@@ -3242,7 +3323,8 @@ static void fuse_lib_create(fuse_req_t req, fuse_ino_t parent,
 		fuse_prepare_interrupt(f, req, &d);
 		err = fuse_fs_create(f->fs, path, mode, fi);
 		if (!err) {
-			err = lookup_path(f, parent, name, path, &e, fi);
+			err = lookup_path(f, parent, name, path, &e,
+					  &iflags, fi);
 			if (err)
 				fuse_fs_release(f->fs, path, fi);
 			else if (!S_ISREG(e.attr.st_mode)) {
@@ -3262,10 +3344,14 @@ static void fuse_lib_create(fuse_req_t req, fuse_ino_t parent,
 		fuse_finish_interrupt(f, req, &d);
 	}
 	if (!err) {
+		int create_res;
+
 		pthread_mutex_lock(&f->lock);
 		get_node(f, e.ino)->open_count++;
 		pthread_mutex_unlock(&f->lock);
-		if (fuse_reply_create(req, &e, fi) == -ENOENT) {
+
+		create_res = fuse_reply_create_iflags(req, &e, iflags, fi);
+		if (create_res == -ENOENT) {
 			/* The open syscall was interrupted, so it
 			   must be cancelled */
 			fuse_do_release(f, e.ino, path, fi);
@@ -3299,13 +3385,16 @@ static void open_auto_cache(struct fuse *f, fuse_ino_t ino, const char *path,
 		if (diff_timespec(&now, &node->stat_updated) >
 		    f->conf.ac_attr_timeout) {
 			struct stat stbuf;
+			unsigned int iflags = 0;
 			int err;
+
 			pthread_mutex_unlock(&f->lock);
-			err = fuse_fs_getattr(f->fs, path, &stbuf, fi);
+			err = getattr(f, path, &stbuf, &iflags, fi);
 			pthread_mutex_lock(&f->lock);
-			if (!err)
+			if (!err) {
 				update_stat(node, &stbuf);
-			else
+				node->iflags = iflags;
+			} else
 				node->cache_valid = 0;
 		}
 	}
@@ -3634,6 +3723,7 @@ static int fill_dir_plus(void *dh_, const char *name, const struct stat *statp,
 		.ino = 0,
 	};
 	struct fuse *f = dh->fuse;
+	unsigned int iflags = 0;
 	int res;
 
 	if ((flags & ~FUSE_FILL_DIR_PLUS) != 0) {
@@ -3658,6 +3748,7 @@ static int fill_dir_plus(void *dh_, const char *name, const struct stat *statp,
 
 	if (off) {
 		size_t newlen;
+		size_t thislen;
 
 		if (dh->filled) {
 			dh->error = -EIO;
@@ -3673,7 +3764,8 @@ static int fill_dir_plus(void *dh_, const char *name, const struct stat *statp,
 
 		if (statp && (flags & FUSE_FILL_DIR_PLUS)) {
 			if (!is_dot_or_dotdot(name)) {
-				res = do_lookup(f, dh->nodeid, name, &e);
+				res = do_lookup(f, dh->nodeid, name, &e,
+						&iflags);
 				if (res) {
 					dh->error = res;
 					return 1;
@@ -3681,10 +3773,12 @@ static int fill_dir_plus(void *dh_, const char *name, const struct stat *statp,
 			}
 		}
 
-		newlen = dh->len +
-			fuse_add_direntry_plus(dh->req, dh->contents + dh->len,
-					       dh->needlen - dh->len, name,
-					       &e, off);
+		thislen = fuse_add_direntry_plus_iflags(dh->req,
+							dh->contents + dh->len,
+							dh->needlen - dh->len,
+							name, iflags, &e, off);
+		newlen = dh->len + thislen;
+
 		if (newlen > dh->needlen)
 			return 1;
 		dh->len = newlen;
@@ -3771,6 +3865,7 @@ static int readdir_fill_from_list(fuse_req_t req, struct fuse_dh *dh,
 		unsigned rem = dh->needlen - dh->len;
 		unsigned thislen;
 		unsigned newlen;
+		unsigned int iflags = 0;
 		pos++;
 
 		if (flags & FUSE_READDIR_PLUS) {
@@ -3782,15 +3877,17 @@ static int readdir_fill_from_list(fuse_req_t req, struct fuse_dh *dh,
 			if (de->flags & FUSE_FILL_DIR_PLUS &&
 			    !is_dot_or_dotdot(de->name)) {
 				res = do_lookup(dh->fuse, dh->nodeid,
-						de->name, &e);
+						de->name, &e, &iflags);
 				if (res) {
 					dh->error = res;
 					return 1;
 				}
 			}
 
-			thislen = fuse_add_direntry_plus(req, p, rem,
-							 de->name, &e, pos);
+			thislen = fuse_add_direntry_plus_iflags(req, p, rem,
+								de->name,
+								iflags, &e,
+								pos);
 		} else {
 			thislen = fuse_add_direntry(req, p, rem,
 						    de->name, &de->stat, pos);

[PATCH 11/18] libfuse: support direct I/O through iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Make it so that fuse servers can ask the kernel fuse driver to use iomap
to support direct IO.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h |    2 ++
 include/fuse_kernel.h |    3 +++
 lib/fuse_lowlevel.c   |    2 ++
 3 files changed, 7 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index faf0bc57bcdbe6..191d9749960992 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1223,6 +1223,8 @@ static inline bool fuse_iomap_need_write_allocate(unsigned int opflags,
 
 /* enable fsdax */
 #define FUSE_IFLAG_DAX			(1U << 0)
+/* use iomap for this inode */
+#define FUSE_IFLAG_IOMAP		(1U << 1)
 
 /* ----------------------------------------------------------- *
  * Compatibility stuff					       *
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index b349ede09e494f..48db6ba118a47c 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -238,6 +238,7 @@
  *
  *  7.99
  *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
+ *  - add FUSE_ATTR_IOMAP to enable iomap for specific inodes
  */
 
 #ifndef _LINUX_FUSE_H
@@ -578,9 +579,11 @@ struct fuse_file_lock {
  *
  * FUSE_ATTR_SUBMOUNT: Object is a submount root
  * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
+ * FUSE_ATTR_IOMAP: Use iomap for this inode
  */
 #define FUSE_ATTR_SUBMOUNT      (1 << 0)
 #define FUSE_ATTR_DAX		(1 << 1)
+#define FUSE_ATTR_IOMAP		(1 << 2)
 
 /**
  * Open flags
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index bddc161412f33e..8654ca263b374d 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -124,6 +124,8 @@ static void convert_stat(const struct stat *stbuf, struct fuse_attr *attr,
 	attr->flags	= 0;
 	if (iflags & FUSE_IFLAG_DAX)
 		attr->flags |= FUSE_ATTR_DAX;
+	if (iflags & FUSE_IFLAG_IOMAP)
+		attr->flags |= FUSE_ATTR_IOMAP;
 }
 
 static void convert_attr(const struct fuse_setattr_in *attr, struct stat *stbuf)

[PATCH 12/18] libfuse: don't allow hardlinking of iomap files in the upper level fuse library

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

The upper level fuse library creates a separate node object for every
(i)node referenced by a directory entry.  Unfortunately, it doesn't
account for the possibility of hardlinks, which means that we can create
multiple nodeids that refer to the same hardlinked inode.  Inode locking
in iomap mode in the kernel relies there only being one inode object for
a hardlinked file, so we cannot allow anyone to hardlink an iomap file.
The client had better not turn on iomap for an existing hardlinked file.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h         |   18 ++++++++++
 lib/fuse.c             |   90 +++++++++++++++++++++++++++++++++++++++++++-----
 lib/fuse_versionscript |    2 +
 3 files changed, 101 insertions(+), 9 deletions(-)


diff --git a/include/fuse.h b/include/fuse.h
index 7256f43fd5c39a..4c4fff837437c8 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -1415,6 +1415,24 @@ int fuse_fs_iomap_device_add(int fd, unsigned int flags);
  */
 int fuse_fs_iomap_device_remove(int device_id);
 
+/**
+ * Decide if we can enable iomap mode for a particular file for an upper-level
+ * fuse server.
+ *
+ * @param statbuf stat information for the file.
+ * @return true if it can be enabled, false if not.
+ */
+bool fuse_fs_can_enable_iomap(const struct stat *statbuf);
+
+/**
+ * Decide if we can enable iomap mode for a particular file for an upper-level
+ * fuse server.
+ *
+ * @param statxbuf statx information for the file.
+ * @return true if it can be enabled, false if not.
+ */
+bool fuse_fs_can_enable_iomapx(const struct statx *statxbuf);
+
 int fuse_notify_poll(struct fuse_pollhandle *ph);
 
 /**
diff --git a/lib/fuse.c b/lib/fuse.c
index 6b211084e2175a..cbf2c5d3a67895 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -3249,10 +3249,66 @@ static void fuse_lib_rename(fuse_req_t req, fuse_ino_t olddir,
 	reply_err(req, err);
 }
 
+/*
+ * Decide if file IO for this inode can use iomap.
+ *
+ * The upper level libfuse creates internal node ids that have nothing to do
+ * with the ext2_ino_t that we give it.  These internal node ids are what
+ * actually gets igetted in the kernel, which means that there can be multiple
+ * fuse_inode objects in the kernel for a single hardlinked inode in the fuse
+ * server.
+ *
+ * What this means, horrifyingly, is that on a fuse filesystem that supports
+ * hard links, the in-kernel i_rwsem does not protect against concurrent writes
+ * between files that point to the same inode.  That in turn means that the
+ * file mode and size can get desynchronized between the multiple fuse_inode
+ * objects.  This also means that we cannot cache iomaps in the kernel AT ALL
+ * because the caches will get out of sync, leading to WARN_ONs from the iomap
+ * zeroing code and probably data corruption after that.
+ *
+ * Therefore, libfuse must never create hardlinks of iomap files, and the
+ * predicates below allow fuse servers to decide if they can turn on iomap for
+ * existing hardlinked files.
+ */
+bool fuse_fs_can_enable_iomap(const struct stat *statbuf)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse_session *se = fuse_get_session(ctxt->fuse);
+
+	if (!(se->conn.want_ext & FUSE_CAP_IOMAP))
+		return false;
+
+	return statbuf->st_nlink < 2;
+}
+
+bool fuse_fs_can_enable_iomapx(const struct statx *statxbuf)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse_session *se = fuse_get_session(ctxt->fuse);
+
+	if (!(se->conn.want_ext & FUSE_CAP_IOMAP))
+		return false;
+
+	return statxbuf->stx_nlink < 2;
+}
+
+static bool fuse_lib_can_link(fuse_req_t req, fuse_ino_t ino)
+{
+	struct fuse *f = req_fuse_prepare(req);
+	struct node *node;
+
+	if (!(req->se->conn.want_ext & FUSE_CAP_IOMAP))
+		return true;
+
+	node = get_node(f, ino);
+	return !(node->iflags & FUSE_IFLAG_IOMAP);
+}
+
 static void fuse_lib_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t newparent,
 			  const char *newname)
 {
 	struct fuse *f = req_fuse_prepare(req);
+	struct fuse_intr_data d;
 	struct fuse_entry_param e;
 	char *oldpath;
 	char *newpath;
@@ -3261,17 +3317,33 @@ static void fuse_lib_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t newparent,
 
 	err = get_path2(f, ino, NULL, newparent, newname,
 			&oldpath, &newpath, NULL, NULL);
-	if (!err) {
-		struct fuse_intr_data d;
+	if (err)
+		goto out_reply;
 
-		fuse_prepare_interrupt(f, req, &d);
-		err = fuse_fs_link(f->fs, oldpath, newpath);
-		if (!err)
-			err = lookup_path(f, newparent, newname, newpath,
-					  &e, &iflags, NULL);
-		fuse_finish_interrupt(f, req, &d);
-		free_path2(f, ino, newparent, NULL, NULL, oldpath, newpath);
+	/*
+	 * The upper level fuse library creates a separate node object for
+	 * every (i)node referenced by a directory entry.  Unfortunately, it
+	 * doesn't account for the possibility of hardlinks, which means that
+	 * we can create multiple nodeids that refer to the same hardlinked
+	 * inode.  Inode locking in iomap mode in the kernel relies there only
+	 * being one inode object for a hardlinked file, so we cannot allow
+	 * anyone to hardlink an iomap file.  The client had better not turn on
+	 * iomap for an existing hardlinked file.
+	 */
+	if (!fuse_lib_can_link(req, ino)) {
+		err = -EPERM;
+		goto out_path;
 	}
+
+	fuse_prepare_interrupt(f, req, &d);
+	err = fuse_fs_link(f->fs, oldpath, newpath);
+	if (!err)
+		err = lookup_path(f, newparent, newname, newpath,
+				  &e, &iflags, NULL);
+	fuse_finish_interrupt(f, req, &d);
+out_path:
+	free_path2(f, ino, newparent, NULL, NULL, oldpath, newpath);
+out_reply:
 	reply_entry(req, &e, iflags, err);
 }
 
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 29a000fff16104..25a3e04c6c5ec7 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -230,6 +230,8 @@ FUSE_3.99 {
 		fuse_reply_create_iflags;
 		fuse_reply_entry_iflags;
 		fuse_add_direntry_plus_iflags;
+		fuse_fs_can_enable_iomap;
+		fuse_fs_can_enable_iomapx;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 13/18] libfuse: allow discovery of the kernel's iomap capabilities

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create a library function so that we can discover the kernel's iomap
capabilities ahead of time.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h   |    7 +++++++
 include/fuse_kernel.h   |    7 +++++++
 include/fuse_lowlevel.h |   10 ++++++++++
 lib/fuse_lowlevel.c     |   19 +++++++++++++++++++
 lib/fuse_versionscript  |    1 +
 5 files changed, 44 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index 191d9749960992..86ae8894d81dbb 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -534,6 +534,13 @@ struct fuse_loop_config_v1 {
 
 #define FUSE_IOCTL_MAX_IOV	256
 
+/**
+ * iomap discovery flags
+ *
+ * FUSE_IOMAP_SUPPORT_FILEIO: basic file I/O functionality through iomap
+ */
+#define FUSE_IOMAP_SUPPORT_FILEIO	(1ULL << 0)
+
 /**
  * Connection information, passed to the ->init() method
  *
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 48db6ba118a47c..ea4243d09db53f 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -1139,12 +1139,19 @@ struct fuse_backing_map {
 	uint64_t	padding;
 };
 
+struct fuse_iomap_support {
+	uint64_t	flags;
+	uint64_t	padding;
+};
+
 /* Device ioctls: */
 #define FUSE_DEV_IOC_MAGIC		229
 #define FUSE_DEV_IOC_CLONE		_IOR(FUSE_DEV_IOC_MAGIC, 0, uint32_t)
 #define FUSE_DEV_IOC_BACKING_OPEN	_IOW(FUSE_DEV_IOC_MAGIC, 1, \
 					     struct fuse_backing_map)
 #define FUSE_DEV_IOC_BACKING_CLOSE	_IOW(FUSE_DEV_IOC_MAGIC, 2, uint32_t)
+#define FUSE_DEV_IOC_IOMAP_SUPPORT	_IOR(FUSE_DEV_IOC_MAGIC, 99, \
+					     struct fuse_iomap_support)
 
 struct fuse_lseek_in {
 	uint64_t	fh;
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index dfe28d33d8d0b8..a4117efdee6dea 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -2574,6 +2574,16 @@ bool fuse_req_is_uring(fuse_req_t req);
 int fuse_req_get_payload(fuse_req_t req, char **payload, size_t *payload_sz,
 			 void **mr);
 
+
+/**
+ * Discover the kernel's iomap capabilities.  Returns FUSE_CAP_IOMAP_* flags.
+ *
+ * @param fd open file descriptor to a fuse device, or -1 if you're running
+ *           in the same process that will call mount().
+ * @return FUSE_IOMAP_SUPPORT_* flags
+ */
+uint64_t fuse_lowlevel_discover_iomap(int fd);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 8654ca263b374d..a20f7fe3752ac5 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -4618,3 +4618,22 @@ int fuse_session_exited(struct fuse_session *se)
 
 	return exited ? 1 : 0;
 }
+
+uint64_t fuse_lowlevel_discover_iomap(int fd)
+{
+	struct fuse_iomap_support ios = { };
+
+	if (fd >= 0) {
+		ioctl(fd, FUSE_DEV_IOC_IOMAP_SUPPORT, &ios);
+		return ios.flags;
+	}
+
+	fd = open("/dev/fuse", O_RDONLY | O_CLOEXEC);
+	if (fd < 0)
+		return 0;
+
+	ioctl(fd, FUSE_DEV_IOC_IOMAP_SUPPORT, &ios);
+	close(fd);
+
+	return ios.flags;
+}
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 25a3e04c6c5ec7..704e8c2908ec4b 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -232,6 +232,7 @@ FUSE_3.99 {
 		fuse_add_direntry_plus_iflags;
 		fuse_fs_can_enable_iomap;
 		fuse_fs_can_enable_iomapx;
+		fuse_lowlevel_discover_iomap;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 14/18] libfuse: add lower level iomap_config implementation

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add FUSE_IOMAP_CONFIG helpers to the low level fuse library.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h   |   31 ++++++++++++++++++
 include/fuse_kernel.h   |   31 ++++++++++++++++++
 include/fuse_lowlevel.h |   27 +++++++++++++++
 lib/fuse_lowlevel.c     |   82 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/fuse_versionscript  |    1 +
 5 files changed, 172 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index 86ae8894d81dbb..59b79b44a36e8d 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1233,6 +1233,37 @@ static inline bool fuse_iomap_need_write_allocate(unsigned int opflags,
 /* use iomap for this inode */
 #define FUSE_IFLAG_IOMAP		(1U << 1)
 
+/* Which fields are set in fuse_iomap_config_out? */
+#define FUSE_IOMAP_CONFIG_SID		(1 << 0ULL)
+#define FUSE_IOMAP_CONFIG_UUID		(1 << 1ULL)
+#define FUSE_IOMAP_CONFIG_BLOCKSIZE	(1 << 2ULL)
+#define FUSE_IOMAP_CONFIG_MAX_LINKS	(1 << 3ULL)
+#define FUSE_IOMAP_CONFIG_TIME		(1 << 4ULL)
+#define FUSE_IOMAP_CONFIG_MAXBYTES	(1 << 5ULL)
+
+struct fuse_iomap_config{
+	uint64_t flags;		/* FUSE_IOMAP_CONFIG_* */
+
+	char s_id[32];		/* Informational name */
+	char s_uuid[16];	/* UUID */
+
+	uint8_t s_uuid_len;	/* length of s_uuid */
+
+	uint8_t s_pad[3];	/* must be zeroes */
+
+	uint32_t s_blocksize;	/* fs block size */
+	uint32_t s_max_links;	/* max hard links */
+
+	/* Granularity of c/m/atime in ns (cannot be worse than a second) */
+	uint32_t s_time_gran;
+
+	/* Time limits for c/m/atime in seconds */
+	int64_t s_time_min;
+	int64_t s_time_max;
+
+	int64_t s_maxbytes;	/* max file size */
+};
+
 /* ----------------------------------------------------------- *
  * Compatibility stuff					       *
  * ----------------------------------------------------------- */
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index ea4243d09db53f..4009d0109711d9 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -239,6 +239,7 @@
  *  7.99
  *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
  *  - add FUSE_ATTR_IOMAP to enable iomap for specific inodes
+ *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
  */
 
 #ifndef _LINUX_FUSE_H
@@ -666,6 +667,7 @@ enum fuse_opcode {
 	FUSE_TMPFILE		= 51,
 	FUSE_STATX		= 52,
 
+	FUSE_IOMAP_CONFIG	= 4092,
 	FUSE_IOMAP_IOEND	= 4093,
 	FUSE_IOMAP_BEGIN	= 4094,
 	FUSE_IOMAP_END		= 4095,
@@ -1363,4 +1365,33 @@ struct fuse_iomap_ioend_in {
 	uint32_t reserved1;	/* zero */
 };
 
+struct fuse_iomap_config_in {
+	uint64_t flags;		/* supported FUSE_IOMAP_CONFIG_* flags */
+	int64_t maxbytes;	/* max supported file size */
+	uint64_t padding[6];	/* zero */
+};
+
+struct fuse_iomap_config_out {
+	uint64_t flags;		/* FUSE_IOMAP_CONFIG_* */
+
+	char s_id[32];		/* Informational name */
+	char s_uuid[16];	/* UUID */
+
+	uint8_t s_uuid_len;	/* length of s_uuid */
+
+	uint8_t s_pad[3];	/* must be zeroes */
+
+	uint32_t s_blocksize;	/* fs block size */
+	uint32_t s_max_links;	/* max hard links */
+
+	/* Granularity of c/m/atime in ns (cannot be worse than a second) */
+	uint32_t s_time_gran;
+
+	/* Time limits for c/m/atime in seconds */
+	int64_t s_time_min;
+	int64_t s_time_max;
+
+	int64_t s_maxbytes;	/* max file size */
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index a4117efdee6dea..b79c73d1573c40 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1408,6 +1408,20 @@ struct fuse_lowlevel_ops {
 			     uint64_t attr_ino, off_t pos, size_t written,
 			     uint32_t ioendflags, int error,
 			     uint64_t new_addr);
+
+	/**
+	 * Configure the filesystem geometry for iomap mode
+	 *
+	 * Valid replies:
+	 *   fuse_reply_iomap_config
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param flags FUSE_IOMAP_CONFIG_* flags that can be passed back
+	 * @param maxbytes maximum supported file size
+	 */
+	void (*iomap_config) (fuse_req_t req, uint64_t flags,
+			      uint64_t maxbytes);
 };
 
 /**
@@ -1898,6 +1912,19 @@ void fuse_iomap_pure_overwrite(struct fuse_file_iomap *write,
 int fuse_reply_iomap_begin(fuse_req_t req, const struct fuse_file_iomap *read,
 			   const struct fuse_file_iomap *write);
 
+/**
+ * Reply with iomap configuration
+ *
+ * Possible requests:
+ *   iomap_config
+ *
+ * @param req request handle
+ * @param cfg iomap configuration
+ * @return zero for success, -errno for failure to send reply
+ */
+int fuse_reply_iomap_config(fuse_req_t req,
+			    const struct fuse_iomap_config *cfg);
+
 /* ----------------------------------------------------------- *
  * Notification						       *
  * ----------------------------------------------------------- */
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index a20f7fe3752ac5..26c23527439feb 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2695,6 +2695,86 @@ static void do_iomap_ioend(fuse_req_t req, const fuse_ino_t nodeid,
 	_do_iomap_ioend(req, nodeid, inarg, NULL);
 }
 
+#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
+#define offsetofend(TYPE, MEMBER) \
+	(offsetof(TYPE, MEMBER)	+ sizeof_field(TYPE, MEMBER))
+
+#define FUSE_IOMAP_CONFIG_V1 (FUSE_IOMAP_CONFIG_SID | \
+			      FUSE_IOMAP_CONFIG_UUID | \
+			      FUSE_IOMAP_CONFIG_BLOCKSIZE | \
+			      FUSE_IOMAP_CONFIG_MAX_LINKS | \
+			      FUSE_IOMAP_CONFIG_TIME | \
+			      FUSE_IOMAP_CONFIG_MAXBYTES)
+
+#define FUSE_IOMAP_CONFIG_ALL (FUSE_IOMAP_CONFIG_V1)
+
+static ssize_t iomap_config_reply_size(const struct fuse_iomap_config *cfg)
+{
+	if (cfg->flags & ~FUSE_IOMAP_CONFIG_ALL)
+		return -EINVAL;
+
+	return offsetofend(struct fuse_iomap_config_out, s_maxbytes);
+}
+
+int fuse_reply_iomap_config(fuse_req_t req, const struct fuse_iomap_config *cfg)
+{
+	struct fuse_iomap_config_out arg = {
+		.flags = cfg->flags,
+	};
+	const ssize_t reply_size = iomap_config_reply_size(cfg);
+
+	if (reply_size < 0)
+		fuse_reply_err(req, -reply_size);
+
+	if (cfg->flags & FUSE_IOMAP_CONFIG_BLOCKSIZE)
+		arg.s_blocksize = cfg->s_blocksize;
+
+	if (cfg->flags & FUSE_IOMAP_CONFIG_SID)
+		memcpy(arg.s_id, cfg->s_id, sizeof(arg.s_id));
+
+	if (cfg->flags & FUSE_IOMAP_CONFIG_UUID) {
+		arg.s_uuid_len = cfg->s_uuid_len;
+		if (arg.s_uuid_len > sizeof(arg.s_uuid))
+			arg.s_uuid_len = sizeof(arg.s_uuid);
+		memcpy(arg.s_uuid, cfg->s_uuid, arg.s_uuid_len);
+	}
+
+	if (cfg->flags & FUSE_IOMAP_CONFIG_MAX_LINKS)
+		arg.s_max_links = cfg->s_max_links;
+
+	if (cfg->flags & FUSE_IOMAP_CONFIG_TIME) {
+		arg.s_time_gran = cfg->s_time_gran;
+		arg.s_time_min = cfg->s_time_min;
+		arg.s_time_max = cfg->s_time_max;
+	}
+
+	if (cfg->flags & FUSE_IOMAP_CONFIG_MAXBYTES)
+		arg.s_maxbytes = cfg->s_maxbytes;
+
+	return send_reply_ok(req, &arg, reply_size);
+}
+
+static void _do_iomap_config(fuse_req_t req, const fuse_ino_t nodeid,
+		      const void *op_in, const void *in_payload)
+{
+	(void)nodeid;
+	(void)in_payload;
+	const struct fuse_iomap_config_in *arg = op_in;
+
+	if (req->se->op.iomap_config)
+		req->se->op.iomap_config(req,
+					 arg->flags & FUSE_IOMAP_CONFIG_ALL,
+					 arg->maxbytes);
+	else
+		fuse_reply_err(req, ENOSYS);
+}
+
+static void do_iomap_config(fuse_req_t req, const fuse_ino_t nodeid,
+			    const void *inarg)
+{
+	_do_iomap_config(req, nodeid, inarg, NULL);
+}
+
 static bool want_flags_valid(uint64_t capable, uint64_t want)
 {
 	uint64_t unknown_flags = want & (~capable);
@@ -3594,6 +3674,7 @@ static struct {
 	[FUSE_COPY_FILE_RANGE] = { do_copy_file_range, "COPY_FILE_RANGE" },
 	[FUSE_LSEEK]	   = { do_lseek,       "LSEEK"	     },
 	[FUSE_STATX]	   = { do_statx,       "STATX"	     },
+	[FUSE_IOMAP_CONFIG]= { do_iomap_config, "IOMAP_CONFIG" },
 	[FUSE_IOMAP_BEGIN] = { do_iomap_begin,	"IOMAP_BEGIN" },
 	[FUSE_IOMAP_END]   = { do_iomap_end,	"IOMAP_END" },
 	[FUSE_IOMAP_IOEND] = { do_iomap_ioend,	"IOMAP_IOEND" },
@@ -3652,6 +3733,7 @@ static struct {
 	[FUSE_COPY_FILE_RANGE]	= { _do_copy_file_range, "COPY_FILE_RANGE" },
 	[FUSE_LSEEK]		= { _do_lseek,		"LSEEK" },
 	[FUSE_STATX]		= { _do_statx,		"STATX" },
+	[FUSE_IOMAP_CONFIG]	= { _do_iomap_config,	"IOMAP_CONFIG" },
 	[FUSE_IOMAP_BEGIN]	= { _do_iomap_begin,	"IOMAP_BEGIN" },
 	[FUSE_IOMAP_END]	= { _do_iomap_end,	"IOMAP_END" },
 	[FUSE_IOMAP_IOEND]	= { _do_iomap_ioend,	"IOMAP_IOEND" },
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 704e8c2908ec4b..6e57e943a60e2d 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -233,6 +233,7 @@ FUSE_3.99 {
 		fuse_fs_can_enable_iomap;
 		fuse_fs_can_enable_iomapx;
 		fuse_lowlevel_discover_iomap;
+		fuse_reply_iomap_config;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 15/18] libfuse: add upper level iomap_config implementation

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add FUSE_IOMAP_CONFIG helpers to the upper level fuse library.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h |    7 +++++++
 lib/fuse.c     |   37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)


diff --git a/include/fuse.h b/include/fuse.h
index 4c4fff837437c8..74b86e8d27fb35 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -896,6 +896,13 @@ struct fuse_operations {
 	 */
 	int (*getattr_iflags) (const char *path, struct stat *buf,
 			       unsigned int *iflags, struct fuse_file_info *fi);
+
+	/**
+	 * Configure the filesystem geometry that will be used by iomap
+	 * files.
+	 */
+	int (*iomap_config) (uint64_t supported_flags, off_t maxbytes,
+			     struct fuse_iomap_config *cfg);
 };
 
 /** Extra context that may be needed by some filesystems
diff --git a/lib/fuse.c b/lib/fuse.c
index cbf2c5d3a67895..177c524eff736b 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -2937,6 +2937,23 @@ static int fuse_fs_iomap_ioend(struct fuse_fs *fs, const char *path,
 				  ioendflags, error, new_addr);
 }
 
+static int fuse_fs_iomap_config(struct fuse_fs *fs, uint64_t flags,
+				uint64_t maxbytes,
+				struct fuse_iomap_config *cfg)
+{
+	fuse_get_context()->private_data = fs->user_data;
+	if (!fs->op.iomap_config)
+		return -ENOSYS;
+
+	if (fs->debug) {
+		fuse_log(FUSE_LOG_DEBUG,
+			 "iomap_config flags 0x%x maxbytes %lld\n",
+			 flags, (long long)maxbytes);
+	}
+
+	return fs->op.iomap_config(flags, maxbytes, cfg);
+}
+
 static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
 			     int valid, struct fuse_file_info *fi)
 {
@@ -4791,6 +4808,25 @@ static void fuse_lib_iomap_ioend(fuse_req_t req, fuse_ino_t nodeid,
 	reply_err(req, err);
 }
 
+static void fuse_lib_iomap_config(fuse_req_t req, uint64_t flags,
+				  uint64_t maxbytes)
+{
+	struct fuse_iomap_config cfg = { };
+	struct fuse *f = req_fuse_prepare(req);
+	struct fuse_intr_data d;
+	int err;
+
+	fuse_prepare_interrupt(f, req, &d);
+	err = fuse_fs_iomap_config(f->fs, flags, maxbytes, &cfg);
+	fuse_finish_interrupt(f, req, &d);
+	if (err) {
+		reply_err(req, err);
+		return;
+	}
+
+	fuse_reply_iomap_config(req, &cfg);
+}
+
 static int clean_delay(struct fuse *f)
 {
 	/*
@@ -4895,6 +4931,7 @@ static struct fuse_lowlevel_ops fuse_path_ops = {
 	.iomap_begin = fuse_lib_iomap_begin,
 	.iomap_end = fuse_lib_iomap_end,
 	.iomap_ioend = fuse_lib_iomap_ioend,
+	.iomap_config = fuse_lib_iomap_config,
 };
 
 int fuse_notify_poll(struct fuse_pollhandle *ph)

[PATCH 16/18] libfuse: add low level code to invalidate iomap block device ranges

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Make it easier to invalidate the page cache for a block device that is
being used in conjunction with iomap.  This allows a fuse server to kill
all cached data for a block that is being freed, so that block reuse
doesn't result in file corruption.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_kernel.h   |    9 +++++++++
 include/fuse_lowlevel.h |   15 +++++++++++++++
 lib/fuse_lowlevel.c     |   22 ++++++++++++++++++++++
 lib/fuse_versionscript  |    1 +
 4 files changed, 47 insertions(+)


diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 4009d0109711d9..861c3d449db788 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -240,6 +240,7 @@
  *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
  *  - add FUSE_ATTR_IOMAP to enable iomap for specific inodes
  *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
+ *  - add FUSE_NOTIFY_IOMAP_DEV_INVAL to invalidate iomap bdev ranges
  */
 
 #ifndef _LINUX_FUSE_H
@@ -689,6 +690,7 @@ enum fuse_notify_code {
 	FUSE_NOTIFY_DELETE = 6,
 	FUSE_NOTIFY_RESEND = 7,
 	FUSE_NOTIFY_INC_EPOCH = 8,
+	FUSE_NOTIFY_IOMAP_DEV_INVAL = 9,
 	FUSE_NOTIFY_CODE_MAX,
 };
 
@@ -1394,4 +1396,11 @@ struct fuse_iomap_config_out {
 	int64_t s_maxbytes;	/* max file size */
 };
 
+struct fuse_iomap_dev_inval {
+	uint32_t dev;		/* device cookie */
+	uint32_t reserved;	/* zero */
+
+	uint64_t offset;	/* range to invalidate pagecache, bytes */
+	uint64_t length;
+};
 #endif /* _LINUX_FUSE_H */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index b79c73d1573c40..687e14b8fea64f 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -2158,6 +2158,21 @@ int fuse_lowlevel_iomap_device_add(struct fuse_session *se, int fd,
  */
 int fuse_lowlevel_iomap_device_remove(struct fuse_session *se, int device_id);
 
+/*
+ * Invalidate the page cache of a block device opened for use with iomap.
+ *
+ * Added in FUSE protocol version 7.99. If the kernel does not support
+ * this (or a newer) version, the function will return -ENOSYS and do
+ * nothing.
+ *
+ * @param se the session object
+ * @param dev device cookie returned by fuse_lowlevel_iomap_add_device
+ * @param offset start of the range to invalidate, in bytes
+ * @return length length of the range to invalidate, in bytes
+ */
+int fuse_lowlevel_iomap_device_invalidate(struct fuse_session *se, int dev,
+					  off_t offset, off_t length);
+
 /* ----------------------------------------------------------- *
  * Utility functions					       *
  * ----------------------------------------------------------- */
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 26c23527439feb..166bd82eca463b 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -3483,6 +3483,28 @@ int fuse_lowlevel_notify_store(struct fuse_session *se, fuse_ino_t ino,
 	return res;
 }
 
+int fuse_lowlevel_iomap_device_invalidate(struct fuse_session *se, int dev,
+					  off_t offset, off_t length)
+{
+	struct fuse_iomap_dev_inval arg = {
+		.dev = dev,
+		.offset = offset,
+		.length = length,
+	};
+	struct iovec iov[2];
+
+	if (!se)
+		return -EINVAL;
+
+	if (!(se->conn.want_ext & FUSE_CAP_IOMAP))
+		return -ENOSYS;
+
+	iov[1].iov_base = &arg;
+	iov[1].iov_len = sizeof(arg);
+
+	return send_notify_iov(se, FUSE_NOTIFY_IOMAP_DEV_INVAL, iov, 2);
+}
+
 struct fuse_retrieve_req {
 	struct fuse_notify_req nreq;
 	void *cookie;
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 6e57e943a60e2d..d268471ae5bd38 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -234,6 +234,7 @@ FUSE_3.99 {
 		fuse_fs_can_enable_iomapx;
 		fuse_lowlevel_discover_iomap;
 		fuse_reply_iomap_config;
+		fuse_lowlevel_iomap_device_invalidate;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 17/18] libfuse: add upper-level API to invalidate parts of an iomap block device

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Wire up the upper-level wrappers to
fuse_lowlevel_iomap_invalidate_device.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h         |   10 ++++++++++
 lib/fuse.c             |    9 +++++++++
 lib/fuse_versionscript |    1 +
 3 files changed, 20 insertions(+)


diff --git a/include/fuse.h b/include/fuse.h
index 74b86e8d27fb35..e53e92786cea08 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -1422,6 +1422,16 @@ int fuse_fs_iomap_device_add(int fd, unsigned int flags);
  */
 int fuse_fs_iomap_device_remove(int device_id);
 
+/**
+ * Invalidate any pagecache for the given iomap (block) device.
+ *
+ * @param device_id device index as returned by fuse_lowlevel_iomap_device_add
+ * @param offset starting offset of the range to invalidate
+ * @param length length of the range to invalidate
+ * @return 0 on success, or negative errno on failure
+ */
+int fuse_fs_iomap_device_invalidate(int device_id, off_t offset, off_t length);
+
 /**
  * Decide if we can enable iomap mode for a particular file for an upper-level
  * fuse server.
diff --git a/lib/fuse.c b/lib/fuse.c
index 177c524eff736b..1c813ec5a697a0 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -2917,6 +2917,15 @@ int fuse_fs_iomap_device_remove(int device_id)
 	return fuse_lowlevel_iomap_device_remove(se, device_id);
 }
 
+int fuse_fs_iomap_device_invalidate(int device_id, off_t offset, off_t length)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse_session *se = fuse_get_session(ctxt->fuse);
+
+	return fuse_lowlevel_iomap_device_invalidate(se, device_id, offset,
+						     length);
+}
+
 static int fuse_fs_iomap_ioend(struct fuse_fs *fs, const char *path,
 			       uint64_t nodeid, uint64_t attr_ino, off_t pos,
 			       size_t written, uint32_t ioendflags, int error,
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index d268471ae5bd38..a275b53c6f9f1a 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -235,6 +235,7 @@ FUSE_3.99 {
 		fuse_lowlevel_discover_iomap;
 		fuse_reply_iomap_config;
 		fuse_lowlevel_iomap_device_invalidate;
+		fuse_fs_iomap_device_invalidate;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 18/18] libfuse: add atomic write support

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add the single flag that we need to turn on atomic write support in
fuse.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h |    4 ++++
 include/fuse_kernel.h |    3 +++
 lib/fuse_lowlevel.c   |    2 ++
 3 files changed, 9 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index 59b79b44a36e8d..eb08320bc8863f 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -540,6 +540,8 @@ struct fuse_loop_config_v1 {
  * FUSE_IOMAP_SUPPORT_FILEIO: basic file I/O functionality through iomap
  */
 #define FUSE_IOMAP_SUPPORT_FILEIO	(1ULL << 0)
+/* untorn writes through iomap */
+#define FUSE_IOMAP_SUPPORT_ATOMIC	(1ULL << 1)
 
 /**
  * Connection information, passed to the ->init() method
@@ -1232,6 +1234,8 @@ static inline bool fuse_iomap_need_write_allocate(unsigned int opflags,
 #define FUSE_IFLAG_DAX			(1U << 0)
 /* use iomap for this inode */
 #define FUSE_IFLAG_IOMAP		(1U << 1)
+/* enable untorn writes */
+#define FUSE_IFLAG_ATOMIC		(1U << 2)
 
 /* Which fields are set in fuse_iomap_config_out? */
 #define FUSE_IOMAP_CONFIG_SID		(1 << 0ULL)
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 861c3d449db788..ed41792f94cf4f 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -241,6 +241,7 @@
  *  - add FUSE_ATTR_IOMAP to enable iomap for specific inodes
  *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
  *  - add FUSE_NOTIFY_IOMAP_DEV_INVAL to invalidate iomap bdev ranges
+ *  - add FUSE_ATTR_ATOMIC for single-fsblock atomic write support
  */
 
 #ifndef _LINUX_FUSE_H
@@ -582,10 +583,12 @@ struct fuse_file_lock {
  * FUSE_ATTR_SUBMOUNT: Object is a submount root
  * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
  * FUSE_ATTR_IOMAP: Use iomap for this inode
+ * FUSE_ATTR_ATOMIC: Enable untorn writes
  */
 #define FUSE_ATTR_SUBMOUNT      (1 << 0)
 #define FUSE_ATTR_DAX		(1 << 1)
 #define FUSE_ATTR_IOMAP		(1 << 2)
+#define FUSE_ATTR_ATOMIC	(1 << 3)
 
 /**
  * Open flags
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 166bd82eca463b..6108b1862a7eb8 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -126,6 +126,8 @@ static void convert_stat(const struct stat *stbuf, struct fuse_attr *attr,
 		attr->flags |= FUSE_ATTR_DAX;
 	if (iflags & FUSE_IFLAG_IOMAP)
 		attr->flags |= FUSE_ATTR_IOMAP;
+	if (iflags & FUSE_IFLAG_ATOMIC)
+		attr->flags |= FUSE_ATTR_ATOMIC;
 }
 
 static void convert_attr(const struct fuse_setattr_in *attr, struct stat *stbuf)

[PATCH 1/1] libfuse: allow root_nodeid mount option

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Allow this mount option so that fuse servers can configure the root
nodeid if they want to.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/mount.c |    1 +
 1 file changed, 1 insertion(+)


diff --git a/lib/mount.c b/lib/mount.c
index 2eb967399c9606..140489fa74bb55 100644
--- a/lib/mount.c
+++ b/lib/mount.c
@@ -100,6 +100,7 @@ static const struct fuse_opt fuse_mount_opts[] = {
 	FUSE_OPT_KEY("defcontext=",		KEY_KERN_OPT),
 	FUSE_OPT_KEY("rootcontext=",		KEY_KERN_OPT),
 	FUSE_OPT_KEY("max_read=",		KEY_KERN_OPT),
+	FUSE_OPT_KEY("root_nodeid=",		KEY_KERN_OPT),
 	FUSE_OPT_KEY("user=",			KEY_MTAB_OPT),
 	FUSE_OPT_KEY("-n",			KEY_MTAB_OPT),
 	FUSE_OPT_KEY("-r",			KEY_RO),

[PATCH 1/4] libfuse: add strictatime/lazytime mount options

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

fuse+iomap leaves the kernel completely in charge of handling
timestamps.  Add the lazytime and strictatime mount options so that
fuse+iomap filesystems can take advantage of those options.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/mount.c |   18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)


diff --git a/lib/mount.c b/lib/mount.c
index 140489fa74bb55..01d473902d50d7 100644
--- a/lib/mount.c
+++ b/lib/mount.c
@@ -117,9 +117,16 @@ static const struct fuse_opt fuse_mount_opts[] = {
 	FUSE_OPT_KEY("dirsync",			KEY_KERN_FLAG),
 	FUSE_OPT_KEY("noatime",			KEY_KERN_FLAG),
 	FUSE_OPT_KEY("nodiratime",		KEY_KERN_FLAG),
-	FUSE_OPT_KEY("nostrictatime",		KEY_KERN_FLAG),
 	FUSE_OPT_KEY("symfollow",		KEY_KERN_FLAG),
 	FUSE_OPT_KEY("nosymfollow",		KEY_KERN_FLAG),
+#ifdef MS_LAZYTIME
+	FUSE_OPT_KEY("lazytime",		KEY_KERN_FLAG),
+	FUSE_OPT_KEY("nolazytime",		KEY_KERN_FLAG),
+#endif
+#ifdef MS_STRICTATIME
+	FUSE_OPT_KEY("strictatime",		KEY_KERN_FLAG),
+	FUSE_OPT_KEY("nostrictatime",		KEY_KERN_FLAG),
+#endif
 	FUSE_OPT_END
 };
 
@@ -190,11 +197,18 @@ static const struct mount_flags mount_flags[] = {
 	{"noatime", MS_NOATIME,	    1},
 	{"nodiratime",	    MS_NODIRATIME,	1},
 	{"norelatime",	    MS_RELATIME,	0},
-	{"nostrictatime",   MS_STRICTATIME,	0},
 	{"symfollow",	    MS_NOSYMFOLLOW,	0},
 	{"nosymfollow",	    MS_NOSYMFOLLOW,	1},
 #ifndef __NetBSD__
 	{"dirsync", MS_DIRSYNC,	    1},
+#endif
+#ifdef MS_LAZYTIME
+	{"lazytime",	    MS_LAZYTIME,	1},
+	{"nolazytime",	    MS_LAZYTIME,	0},
+#endif
+#ifdef MS_STRICTATIME
+	{"strictatime",	    MS_STRICTATIME,	1},
+	{"nostrictatime",   MS_STRICTATIME,	0},
 #endif
 	{NULL,	    0,		    0}
 };

[PATCH 2/4] libfuse: set sync, immutable, and append when loading files

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add these three fuse_attr::flags bits so that servers can mark a file as
immutable or append-only and have the kernel advertise and enforce that.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h |    6 ++++++
 include/fuse_kernel.h |    8 ++++++++
 lib/fuse_lowlevel.c   |    6 ++++++
 3 files changed, 20 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index eb08320bc8863f..9016721320eb5a 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1236,6 +1236,12 @@ static inline bool fuse_iomap_need_write_allocate(unsigned int opflags,
 #define FUSE_IFLAG_IOMAP		(1U << 1)
 /* enable untorn writes */
 #define FUSE_IFLAG_ATOMIC		(1U << 2)
+/* file writes are synchronous */
+#define FUSE_IFLAG_SYNC			(1U << 3)
+/* file is immutable */
+#define FUSE_IFLAG_IMMUTABLE		(1U << 4)
+/* file is append only */
+#define FUSE_IFLAG_APPEND		(1U << 5)
 
 /* Which fields are set in fuse_iomap_config_out? */
 #define FUSE_IOMAP_CONFIG_SID		(1 << 0ULL)
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index ed41792f94cf4f..4721c4e36159e1 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -242,6 +242,8 @@
  *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
  *  - add FUSE_NOTIFY_IOMAP_DEV_INVAL to invalidate iomap bdev ranges
  *  - add FUSE_ATTR_ATOMIC for single-fsblock atomic write support
+ *  - add FUSE_ATTR_{SYNC,IMMUTABLE,APPEND} for VFS enforcement of file
+ *    attributes
  */
 
 #ifndef _LINUX_FUSE_H
@@ -584,11 +586,17 @@ struct fuse_file_lock {
  * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
  * FUSE_ATTR_IOMAP: Use iomap for this inode
  * FUSE_ATTR_ATOMIC: Enable untorn writes
+ * FUSE_ATTR_SYNC: File writes are always synchronous
+ * FUSE_ATTR_IMMUTABLE: File is immutable
+ * FUSE_ATTR_APPEND: File is append-only
  */
 #define FUSE_ATTR_SUBMOUNT      (1 << 0)
 #define FUSE_ATTR_DAX		(1 << 1)
 #define FUSE_ATTR_IOMAP		(1 << 2)
 #define FUSE_ATTR_ATOMIC	(1 << 3)
+#define FUSE_ATTR_SYNC		(1 << 4)
+#define FUSE_ATTR_IMMUTABLE	(1 << 5)
+#define FUSE_ATTR_APPEND	(1 << 6)
 
 /**
  * Open flags
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 6108b1862a7eb8..a6294c5c065cd2 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -128,6 +128,12 @@ static void convert_stat(const struct stat *stbuf, struct fuse_attr *attr,
 		attr->flags |= FUSE_ATTR_IOMAP;
 	if (iflags & FUSE_IFLAG_ATOMIC)
 		attr->flags |= FUSE_ATTR_ATOMIC;
+	if (iflags & FUSE_IFLAG_SYNC)
+		attr->flags |= FUSE_ATTR_SYNC;
+	if (iflags & FUSE_IFLAG_IMMUTABLE)
+		attr->flags |= FUSE_ATTR_IMMUTABLE;
+	if (iflags & FUSE_IFLAG_APPEND)
+		attr->flags |= FUSE_ATTR_APPEND;
 }
 
 static void convert_attr(const struct fuse_setattr_in *attr, struct stat *stbuf)

[PATCH 3/4] libfuse: wire up FUSE_SYNCFS to the low level library

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create hooks in the lowlevel library for syncfs.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_lowlevel.h |   16 ++++++++++++++++
 lib/fuse_lowlevel.c     |   19 +++++++++++++++++++
 2 files changed, 35 insertions(+)


diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 687e14b8fea64f..9de93392d6df67 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1422,6 +1422,22 @@ struct fuse_lowlevel_ops {
 	 */
 	void (*iomap_config) (fuse_req_t req, uint64_t flags,
 			      uint64_t maxbytes);
+
+	/**
+	 * Flush the entire filesystem to disk.
+	 *
+	 * If this request is answered with an error code of ENOSYS, this is
+	 * treated as a permanent failure, i.e. all future syncfs() requests
+	 * will fail with the same error code without being sent to the
+	 * filesystem process.
+	 *
+	 * Valid replies:
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param ino the inode number
+	 */
+	void (*syncfs) (fuse_req_t req, fuse_ino_t ino);
 };
 
 /**
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index a6294c5c065cd2..668645dd1c2e08 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2783,6 +2783,23 @@ static void do_iomap_config(fuse_req_t req, const fuse_ino_t nodeid,
 	_do_iomap_config(req, nodeid, inarg, NULL);
 }
 
+static void _do_syncfs(fuse_req_t req, const fuse_ino_t nodeid,
+		      const void *op_in, const void *in_payload)
+{
+	(void)op_in;
+	(void)in_payload;
+
+	if (req->se->op.syncfs)
+		req->se->op.syncfs(req, nodeid);
+	else
+		fuse_reply_err(req, ENOSYS);
+}
+
+static void do_syncfs(fuse_req_t req, const fuse_ino_t nodeid, const void *inarg)
+{
+	_do_syncfs(req, nodeid, inarg, NULL);
+}
+
 static bool want_flags_valid(uint64_t capable, uint64_t want)
 {
 	uint64_t unknown_flags = want & (~capable);
@@ -3704,6 +3721,7 @@ static struct {
 	[FUSE_COPY_FILE_RANGE] = { do_copy_file_range, "COPY_FILE_RANGE" },
 	[FUSE_LSEEK]	   = { do_lseek,       "LSEEK"	     },
 	[FUSE_STATX]	   = { do_statx,       "STATX"	     },
+	[FUSE_SYNCFS]	   = { do_syncfs,	"SYNCFS"     },
 	[FUSE_IOMAP_CONFIG]= { do_iomap_config, "IOMAP_CONFIG" },
 	[FUSE_IOMAP_BEGIN] = { do_iomap_begin,	"IOMAP_BEGIN" },
 	[FUSE_IOMAP_END]   = { do_iomap_end,	"IOMAP_END" },
@@ -3763,6 +3781,7 @@ static struct {
 	[FUSE_COPY_FILE_RANGE]	= { _do_copy_file_range, "COPY_FILE_RANGE" },
 	[FUSE_LSEEK]		= { _do_lseek,		"LSEEK" },
 	[FUSE_STATX]		= { _do_statx,		"STATX" },
+	[FUSE_SYNCFS]		= { _do_syncfs,		"SYNCFS" },
 	[FUSE_IOMAP_CONFIG]	= { _do_iomap_config,	"IOMAP_CONFIG" },
 	[FUSE_IOMAP_BEGIN]	= { _do_iomap_begin,	"IOMAP_BEGIN" },
 	[FUSE_IOMAP_END]	= { _do_iomap_end,	"IOMAP_END" },

[PATCH 4/4] libfuse: add syncfs support to the upper library

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Support syncfs in the upper level library.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h |    5 +++++
 lib/fuse.c     |   31 +++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)


diff --git a/include/fuse.h b/include/fuse.h
index e53e92786cea08..0b81a1259c4f09 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -903,6 +903,11 @@ struct fuse_operations {
 	 */
 	int (*iomap_config) (uint64_t supported_flags, off_t maxbytes,
 			     struct fuse_iomap_config *cfg);
+
+	/**
+	 * Flush the entire filesystem to disk.
+	 */
+	int (*syncfs) (const char *path);
 };
 
 /** Extra context that may be needed by some filesystems
diff --git a/lib/fuse.c b/lib/fuse.c
index 1c813ec5a697a0..ac0206f6ed4544 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -2963,6 +2963,16 @@ static int fuse_fs_iomap_config(struct fuse_fs *fs, uint64_t flags,
 	return fs->op.iomap_config(flags, maxbytes, cfg);
 }
 
+static int fuse_fs_syncfs(struct fuse_fs *fs, const char *path)
+{
+	fuse_get_context()->private_data = fs->user_data;
+	if (!fs->op.syncfs)
+		return -ENOSYS;
+	if (fs->debug)
+		fuse_log(FUSE_LOG_DEBUG, "syncfs[%s]\n", path);
+	return fs->op.syncfs(path);
+}
+
 static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
 			     int valid, struct fuse_file_info *fi)
 {
@@ -4836,6 +4846,26 @@ static void fuse_lib_iomap_config(fuse_req_t req, uint64_t flags,
 	fuse_reply_iomap_config(req, &cfg);
 }
 
+static void fuse_lib_syncfs(fuse_req_t req, fuse_ino_t ino)
+{
+	struct fuse *f = req_fuse_prepare(req);
+	struct fuse_intr_data d;
+	char *path;
+	int err;
+
+	err = get_path(f, ino, &path);
+	if (err) {
+		reply_err(req, err);
+		return;
+	}
+
+	fuse_prepare_interrupt(f, req, &d);
+	err = fuse_fs_syncfs(f->fs, path);
+	fuse_finish_interrupt(f, req, &d);
+	free_path(f, ino, path);
+	reply_err(req, err);
+}
+
 static int clean_delay(struct fuse *f)
 {
 	/*
@@ -4937,6 +4967,7 @@ static struct fuse_lowlevel_ops fuse_path_ops = {
 #ifdef HAVE_STATX
 	.statx = fuse_lib_statx,
 #endif
+	.syncfs = fuse_lib_syncfs,
 	.iomap_begin = fuse_lib_iomap_begin,
 	.iomap_end = fuse_lib_iomap_end,
 	.iomap_ioend = fuse_lib_iomap_ioend,

[PATCH 1/3] libfuse: enable iomap cache management for lowlevel fuse

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add the library methods so that fuse servers can manage an in-kernel
iomap cache.  This enables better performance on small IOs and is
required if the filesystem needs synchronization between pagecache
writes and writeback.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h   |   12 ++++++++
 include/fuse_kernel.h   |   26 +++++++++++++++++
 include/fuse_lowlevel.h |   41 ++++++++++++++++++++++++++
 lib/fuse_lowlevel.c     |   73 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/fuse_versionscript  |    2 +
 5 files changed, 154 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index 9016721320eb5a..ff245a82dd4069 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1158,6 +1158,10 @@ int fuse_convert_to_conn_want_ext(struct fuse_conn_info *conn);
 
 /* fuse-specific mapping type indicating that writes use the read mapping */
 #define FUSE_IOMAP_TYPE_PURE_OVERWRITE	(255)
+/* fuse-specific mapping type saying the server has populated the cache */
+#define FUSE_IOMAP_TYPE_RETRY_CACHE	(254)
+/* do not upsert this mapping */
+#define FUSE_IOMAP_TYPE_NOCACHE		(253)
 
 #define FUSE_IOMAP_DEV_NULL		(0U)	/* null device cookie */
 
@@ -1274,6 +1278,14 @@ struct fuse_iomap_config{
 	int64_t s_maxbytes;	/* max file size */
 };
 
+/* invalidate to end of file */
+#define FUSE_IOMAP_INVAL_TO_EOF		(~0ULL)
+
+struct fuse_iomap_inval {
+	uint64_t offset;	/* file offset to invalidate, bytes */
+	uint64_t length;	/* length to invalidate, bytes */
+};
+
 /* ----------------------------------------------------------- *
  * Compatibility stuff					       *
  * ----------------------------------------------------------- */
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 4721c4e36159e1..3bb26fce2f6a0e 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -244,6 +244,8 @@
  *  - add FUSE_ATTR_ATOMIC for single-fsblock atomic write support
  *  - add FUSE_ATTR_{SYNC,IMMUTABLE,APPEND} for VFS enforcement of file
  *    attributes
+ *  - add FUSE_NOTIFY_IOMAP_UPSERT and FUSE_NOTIFY_IOMAP_INVAL so fuse servers
+ *    can cache iomappings in the kernel
  */
 
 #ifndef _LINUX_FUSE_H
@@ -702,6 +704,8 @@ enum fuse_notify_code {
 	FUSE_NOTIFY_RESEND = 7,
 	FUSE_NOTIFY_INC_EPOCH = 8,
 	FUSE_NOTIFY_IOMAP_DEV_INVAL = 9,
+	FUSE_NOTIFY_IOMAP_UPSERT = 10,
+	FUSE_NOTIFY_IOMAP_INVAL = 11,
 	FUSE_NOTIFY_CODE_MAX,
 };
 
@@ -1414,4 +1418,26 @@ struct fuse_iomap_dev_inval {
 	uint64_t offset;	/* range to invalidate pagecache, bytes */
 	uint64_t length;
 };
+
+struct fuse_iomap_inval_out {
+	uint64_t nodeid;	/* Inode ID */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+
+	uint64_t read_offset;	/* range to invalidate read iomaps, bytes */
+	uint64_t read_length;	/* can be FUSE_IOMAP_INVAL_TO_EOF */
+
+	uint64_t write_offset;	/* range to invalidate write iomaps, bytes */
+	uint64_t write_length;	/* can be FUSE_IOMAP_INVAL_TO_EOF */
+};
+
+struct fuse_iomap_upsert_out {
+	uint64_t nodeid;	/* Inode ID */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+
+	/* read file data from here */
+	struct fuse_iomap_io	read;
+
+	/* write file data to here, if applicable */
+	struct fuse_iomap_io	write;
+};
 #endif /* _LINUX_FUSE_H */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 9de93392d6df67..1d73f2befc5f3c 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -2189,6 +2189,47 @@ int fuse_lowlevel_iomap_device_remove(struct fuse_session *se, int device_id);
 int fuse_lowlevel_iomap_device_invalidate(struct fuse_session *se, int dev,
 					  off_t offset, off_t length);
 
+/*
+ * Upsert some file mapping information into the kernel.  This is necessary
+ * for filesystems that require coordination of mapping state changes between
+ * buffered writes and writeback, and desirable for better performance
+ * elsewhere.
+ *
+ * Added in FUSE protocol version 7.99. If the kernel does not support
+ * this (or a newer) version, the function will return -ENOSYS and do
+ * nothing.
+ *
+ * @param se the session object
+ * @param nodeid the inode number
+ * @param attr_ino inode number as told by fuse_attr::ino
+ * @param read mapping information for file reads
+ * @param write mapping information for file writes
+ * @return zero for success, -errno for failure
+ */
+int fuse_lowlevel_notify_iomap_upsert(struct fuse_session *se,
+				      fuse_ino_t nodeid, uint64_t attr_ino,
+				      const struct fuse_file_iomap *read,
+				      const struct fuse_file_iomap *write);
+
+/**
+ * Invalidate some file mapping information in the kernel.
+ *
+ * Added in FUSE protocol version 7.99. If the kernel does not support
+ * this (or a newer) version, the function will return -ENOSYS and do
+ * nothing.
+ *
+ * @param se the session object
+ * @param nodeid the inode number
+ * @param attr_ino inode number as told by fuse_attr::ino
+ * @param read read mapping range to invalidate
+ * @param write write mapping range to invalidate
+ * @return zero for success, -errno for failure
+ */
+int fuse_lowlevel_notify_iomap_inval(struct fuse_session *se,
+				     fuse_ino_t nodeid, uint64_t attr_ino,
+				     const struct fuse_iomap_inval *read,
+				     const struct fuse_iomap_inval *write);
+
 /* ----------------------------------------------------------- *
  * Utility functions					       *
  * ----------------------------------------------------------- */
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 668645dd1c2e08..1dc0fcbe54be6c 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -3530,6 +3530,79 @@ int fuse_lowlevel_iomap_device_invalidate(struct fuse_session *se, int dev,
 	return send_notify_iov(se, FUSE_NOTIFY_IOMAP_DEV_INVAL, iov, 2);
 }
 
+int fuse_lowlevel_notify_iomap_upsert(struct fuse_session *se,
+				      fuse_ino_t nodeid, uint64_t attr_ino,
+				      const struct fuse_file_iomap *read,
+				      const struct fuse_file_iomap *write)
+{
+	struct fuse_iomap_upsert_out outarg = {
+		.nodeid		= nodeid,
+		.attr_ino	= attr_ino,
+		.read		= {
+			.type	= FUSE_IOMAP_TYPE_NOCACHE,
+		},
+		.write		= {
+			.type	= FUSE_IOMAP_TYPE_NOCACHE,
+		}
+	};
+	struct iovec iov[2];
+
+	if (!se)
+		return -EINVAL;
+
+	if (se->conn.proto_minor < 99)
+		return -ENOSYS;
+
+	if (!read && !write)
+		return 0;
+
+	if (read)
+		fuse_iomap_to_kernel(&outarg.read, read);
+
+	if (write)
+		fuse_iomap_to_kernel(&outarg.write, write);
+
+	iov[1].iov_base = &outarg;
+	iov[1].iov_len = sizeof(outarg);
+
+	return send_notify_iov(se, FUSE_NOTIFY_IOMAP_UPSERT, iov, 2);
+}
+
+int fuse_lowlevel_notify_iomap_inval(struct fuse_session *se,
+				     fuse_ino_t nodeid, uint64_t attr_ino,
+				     const struct fuse_iomap_inval *read,
+				     const struct fuse_iomap_inval *write)
+{
+	struct fuse_iomap_inval_out outarg = {
+		.nodeid		= nodeid,
+		.attr_ino	= attr_ino,
+	};
+	struct iovec iov[2];
+
+	if (!se)
+		return -EINVAL;
+
+	if (se->conn.proto_minor < 99)
+		return -ENOSYS;
+
+	if (!read && !write)
+		return 0;
+
+	if (read) {
+		outarg.read_offset = read->offset;
+		outarg.read_length = read->length;
+	}
+	if (write) {
+		outarg.write_offset = write->offset;
+		outarg.write_length = write->length;
+	}
+
+	iov[1].iov_base = &outarg;
+	iov[1].iov_len = sizeof(outarg);
+
+	return send_notify_iov(se, FUSE_NOTIFY_IOMAP_INVAL, iov, 2);
+}
+
 struct fuse_retrieve_req {
 	struct fuse_notify_req nreq;
 	void *cookie;
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index a275b53c6f9f1a..48918d94d822e0 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -236,6 +236,8 @@ FUSE_3.99 {
 		fuse_reply_iomap_config;
 		fuse_lowlevel_iomap_device_invalidate;
 		fuse_fs_iomap_device_invalidate;
+		fuse_lowlevel_notify_iomap_upsert;
+		fuse_lowlevel_notify_iomap_inval;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 2/3] libfuse: add upper-level iomap cache management

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Make it so that upper-level fuse servers can use the iomap cache too.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse.h         |   31 +++++++++++++++++++++++++++++++
 lib/fuse.c             |   30 ++++++++++++++++++++++++++++++
 lib/fuse_versionscript |    2 ++
 3 files changed, 63 insertions(+)


diff --git a/include/fuse.h b/include/fuse.h
index 0b81a1259c4f09..baf7a2e90af5e7 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -1455,6 +1455,37 @@ bool fuse_fs_can_enable_iomap(const struct stat *statbuf);
  */
 bool fuse_fs_can_enable_iomapx(const struct statx *statxbuf);
 
+/*
+ * Upsert some file mapping information into the kernel.  This is necessary
+ * for filesystems that require coordination of mapping state changes between
+ * buffered writes and writeback, and desirable for better performance
+ * elsewhere.
+ *
+ * @param nodeid the inode number
+ * @param attr_ino inode number as told by fuse_attr::ino
+ * @param read mapping information for file reads
+ * @param write mapping information for file writes
+ * @return zero for success, -errno for failure
+ */
+int fuse_fs_iomap_upsert(uint64_t nodeid, uint64_t attr_ino,
+			 const struct fuse_file_iomap *read,
+			 const struct fuse_file_iomap *write);
+
+/**
+ * Invalidate some file mapping information in the kernel.
+ *
+ * @param nodeid the inode number
+ * @param attr_ino inode number as told by fuse_attr::ino
+ * @param read_off start of the range of read mappings to invalidate
+ * @param read_len length of the range of read mappings to invalidate
+ * @param write_off start of the range of write mappings to invalidate
+ * @param write_len length of the range of write mappings to invalidate
+ * @return zero for success, -errno for failure
+ */
+int fuse_fs_iomap_inval(uint64_t nodeid, uint64_t attr_ino, loff_t read_off,
+			uint64_t read_len, loff_t write_off,
+			uint64_t write_len);
+
 int fuse_notify_poll(struct fuse_pollhandle *ph);
 
 /**
diff --git a/lib/fuse.c b/lib/fuse.c
index ac0206f6ed4544..372363f0089284 100644
--- a/lib/fuse.c
+++ b/lib/fuse.c
@@ -2973,6 +2973,36 @@ static int fuse_fs_syncfs(struct fuse_fs *fs, const char *path)
 	return fs->op.syncfs(path);
 }
 
+int fuse_fs_iomap_upsert(uint64_t nodeid, uint64_t attr_ino,
+			 const struct fuse_file_iomap *read,
+			 const struct fuse_file_iomap *write)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse_session *se = fuse_get_session(ctxt->fuse);
+
+	return fuse_lowlevel_notify_iomap_upsert(se, nodeid, attr_ino,
+						 read, write);
+}
+
+int fuse_fs_iomap_inval(uint64_t nodeid, uint64_t attr_ino, loff_t read_off,
+			uint64_t read_len, loff_t write_off,
+			uint64_t write_len)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse_session *se = fuse_get_session(ctxt->fuse);
+	struct fuse_iomap_inval read = {
+		.offset = read_off,
+		.length = read_len,
+	};
+	struct fuse_iomap_inval write = {
+		.offset = write_off,
+		.length = write_len,
+	};
+
+	return fuse_lowlevel_notify_iomap_inval(se, nodeid, attr_ino, &read,
+						&write);
+}
+
 static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
 			     int valid, struct fuse_file_info *fi)
 {
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 48918d94d822e0..db95fc6e7b1b41 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -238,6 +238,8 @@ FUSE_3.99 {
 		fuse_fs_iomap_device_invalidate;
 		fuse_lowlevel_notify_iomap_upsert;
 		fuse_lowlevel_notify_iomap_inval;
+		fuse_fs_iomap_upsert;
+		fuse_fs_iomap_inval;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 3/3] libfuse: enable iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Remove the guard that we used to avoid bisection problems.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/fuse_lowlevel.c |    2 --
 1 file changed, 2 deletions(-)


diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 1dc0fcbe54be6c..460ade5a9704a4 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2997,8 +2997,6 @@ _do_init(fuse_req_t req, const fuse_ino_t nodeid, const void *op_in,
 			se->conn.capable_ext |= FUSE_CAP_OVER_IO_URING;
 		if (inargflags & FUSE_IOMAP)
 			se->conn.capable_ext |= FUSE_CAP_IOMAP;
-		/* Don't let anyone touch iomap until the end of the patchset. */
-		se->conn.capable_ext &= ~FUSE_CAP_IOMAP;
 	} else {
 		se->conn.max_readahead = 0;
 	}

[PATCH 1/4] libfuse: add systemd/inetd socket service mounting helper

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create a mount.service helper that can start a fuse server that runs
as a socket-based systemd (or inetd) service.  To make things simpler
for fuse server authors, define a new library interface to wrap all the
functionality so that they don't have to know the details

This enables untrusted ext4 mounts via systemd service containers, which
avoids the problem of malicious filesystems compromising the integrity
of the running kernel through memory corruption.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_service.h      |  151 +++++++
 include/fuse_service_priv.h |   98 ++++
 lib/fuse_i.h                |    5 
 util/mount_service.h        |   32 +
 doc/fuservicemount3.8       |   24 +
 doc/meson.build             |    3 
 include/meson.build         |    4 
 lib/fuse_service.c          |  764 ++++++++++++++++++++++++++++++++++
 lib/fuse_service_stub.c     |   90 ++++
 lib/fuse_versionscript      |   13 +
 lib/helper.c                |   53 ++
 lib/meson.build             |   14 +
 lib/mount.c                 |   57 ++-
 meson.build                 |   36 ++
 meson_options.txt           |    6 
 util/fuservicemount.c       |   18 +
 util/meson.build            |    9 
 util/mount_service.c        |  962 +++++++++++++++++++++++++++++++++++++++++++
 18 files changed, 2325 insertions(+), 14 deletions(-)
 create mode 100644 include/fuse_service.h
 create mode 100644 include/fuse_service_priv.h
 create mode 100644 util/mount_service.h
 create mode 100644 doc/fuservicemount3.8
 create mode 100644 lib/fuse_service.c
 create mode 100644 lib/fuse_service_stub.c
 create mode 100644 util/fuservicemount.c
 create mode 100644 util/mount_service.c


diff --git a/include/fuse_service.h b/include/fuse_service.h
new file mode 100644
index 00000000000000..7c44c701bd695b
--- /dev/null
+++ b/include/fuse_service.h
@@ -0,0 +1,151 @@
+/*  FUSE: Filesystem in Userspace
+  Copyright (C) 2025 Oracle.
+  Author: Darrick J. Wong <djwong@kernel.org>
+
+  This program can be distributed under the terms of the GNU LGPLv2.
+  See the file LGPL2.txt.
+*/
+#ifndef FUSE_SERVICE_H_
+#define FUSE_SERVICE_H_
+
+struct fuse_service;
+
+/**
+ * Accept a socket created by mount.service for information exchange.
+ *
+ * @param sfp pointer to pointer to a service context
+ * @return -1 on error, 0 on success
+ */
+int fuse_service_accept(struct fuse_service **sfp);
+
+/**
+ * Has the fuse server accepted a service context?
+ *
+ * @param sf service context
+ */
+static inline bool fuse_service_accepted(struct fuse_service *sf)
+{
+	return sf != NULL;
+}
+
+/**
+ * Release all resources associated with the service context.
+ *
+ * @param sfp service context
+ */
+void fuse_service_release(struct fuse_service *sf);
+
+/**
+ * Destroy a service context and release all resources
+ *
+ * @param sfp pointer to pointer to a service context
+ */
+void fuse_service_destroy(struct fuse_service **sfp);
+
+/**
+ * Append the command line arguments from the mount service helper to an
+ * existing fuse_args structure.  The fuse_args should have been initialized
+ * with the argc and argv passed to main().
+ *
+ * @param sfp service context
+ * @param args arguments to modify (input+output)
+ * @return -1 on success, 0 on success
+ */
+int fuse_service_append_args(struct fuse_service *sf, struct fuse_args *args);
+
+/**
+ * Generate the effective fuse server command line from the args structure.
+ * The args structure should be the outcome from fuse_service_append_args.
+ * The resulting string is suitable for setproctitle and must be freed by the
+ * callre.
+ *
+ * @param argc argument count passed to main()
+ * @param argv argument vector passed to main()
+ * @param args fuse args structure
+ * @return effective command line string, or NULL
+ */
+char *fuse_service_cmdline(int argc, char *argv[], struct fuse_args *args);
+
+/**
+ * Take the fuse device fd passed from the mount.service helper
+ *
+ * @return device fd on success, -1 on error
+ */
+int fuse_service_take_fusedev(struct fuse_service *sfp);
+
+/**
+ * Utility function to parse common options for simple file systems
+ * using the low-level API. A help text that describes the available
+ * options can be printed with `fuse_cmdline_help`. A single
+ * non-option argument is treated as the mountpoint. Multiple
+ * non-option arguments will result in an error.
+ *
+ * If neither -o subtype= or -o fsname= options are given, a new
+ * subtype option will be added and set to the basename of the program
+ * (the fsname will remain unset, and then defaults to "fuse").
+ *
+ * Known options will be removed from *args*, unknown options will
+ * remain. The mountpoint will not be checked here; that is the job of
+ * mount.service.
+ *
+ * @param args argument vector (input+output)
+ * @param opts output argument for parsed options
+ * @return 0 on success, -1 on failure
+ */
+int fuse_service_parse_cmdline_opts(struct fuse_args *args,
+				    struct fuse_cmdline_opts *opts);
+
+/**
+ * Ask the mount.service helper to open a file on behalf of the fuse server.
+ *
+ * @param sf service context
+ * @param path path to file
+ * @param flags O_ flags
+ * @param mode mode with which to create the file
+ * @return 0 on success, -1 on failure
+ */
+int fuse_service_request_file(struct fuse_service *sf, const char *path,
+			      int flags, mode_t mode);
+
+/**
+ * Receive a file perviously requested.
+ *
+ * @param sf service context
+ * @param path to file
+ * @fdp pointer to file descriptor
+ * @return 0 on success, -1 on socket communication failure, -2 on file open
+ * failure
+ */
+int fuse_service_receive_file(struct fuse_service *sf,
+			      const char *path, int *fdp);
+
+/**
+ * Prevent the mount.service server from sending us any more open files.
+ *
+ * @param sf service context
+ */
+int fuse_service_finish_file_requests(struct fuse_service *sf);
+
+/**
+ * Ask the mount.service helper to mount the filesystem for us.  The fuse client
+ * will begin sending requests to the fuse server immediately after this.
+ *
+ * @param sf service context
+ * @param se fuse session
+ * @param mountpoint place to mount the filesystem
+ * @return 0 on success, -1 on error
+ */
+int fuse_service_mount(struct fuse_service *sf, struct fuse_session *se,
+		       const char *mountpoint);
+
+/**
+ * Bid farewell to the mount.service helper.  It is still necessary to call
+ * fuse_service_destroy after this.
+ *
+ * @param sf service context
+ * @param error any additional errors to send to the mount helper
+ * @return 0 on success, -1 on error
+ */
+int fuse_service_send_goodbye(struct fuse_service *sf, int error);
+
+#endif /* FUSE_SERVICE_H_ */
diff --git a/include/fuse_service_priv.h b/include/fuse_service_priv.h
new file mode 100644
index 00000000000000..1c01a7ba9614f2
--- /dev/null
+++ b/include/fuse_service_priv.h
@@ -0,0 +1,98 @@
+/*  FUSE: Filesystem in Userspace
+  Copyright (C) 2025 Oracle.
+  Author: Darrick J. Wong <djwong@kernel.org>
+
+  This program can be distributed under the terms of the GNU LGPLv2.
+  See the file LGPL2.txt.
+*/
+#ifndef FUSE_SERVICE_PRIV_H_
+#define FUSE_SERVICE_PRIV_H_
+
+struct fuse_service_memfd_arg {
+	__be32 pos;
+	__be32 len;
+};
+
+struct fuse_service_memfd_argv {
+	__be32 magic;
+	__be32 argc;
+};
+
+#define FUSE_SERVICE_ARGS_MAGIC		0x41524753	/* ARGS */
+
+/* mount.service sends a hello to the server and it replies */
+#define FUSE_SERVICE_HELLO_CMD		0x53414654	/* SAFT */
+#define FUSE_SERVICE_HELLO_REPLY	0x4c415354	/* LAST */
+
+/* fuse servers send commands to mount.service */
+#define FUSE_SERVICE_OPEN_CMD		0x4f50454e	/* OPEN */
+#define FUSE_SERVICE_FSOPEN_CMD		0x54595045	/* TYPE */
+#define FUSE_SERVICE_SOURCE_CMD		0x4e414d45	/* NAME */
+#define FUSE_SERVICE_MNTOPTS_CMD	0x4f505453	/* OPTS */
+#define FUSE_SERVICE_MNTPT_CMD		0x4d4e5450	/* MNTP */
+#define FUSE_SERVICE_MOUNT_CMD		0x444f4954	/* DOIT */
+#define FUSE_SERVICE_BYE_CMD		0x42594545	/* BYEE */
+
+/* mount.service sends replies to the fuse server */
+#define FUSE_SERVICE_OPEN_REPLY		0x46494c45	/* FILE */
+#define FUSE_SERVICE_SIMPLE_REPLY	0x5245504c	/* REPL */
+
+struct fuse_service_packet {
+	__be32 magic;			/* FUSE_SERVICE_*_{CMD,REPLY} */
+};
+
+struct fuse_service_simple_reply {
+	struct fuse_service_packet p;
+	__be32 error;
+};
+
+struct fuse_service_requested_file {
+	struct fuse_service_packet p;
+	__be32 error;			/* positive errno */
+	char path[];
+};
+
+static inline size_t sizeof_fuse_service_requested_file(size_t pathlen)
+{
+	return sizeof(struct fuse_service_requested_file) + pathlen + 1;
+}
+
+struct fuse_service_open_command {
+	struct fuse_service_packet p;
+	__be32 flags;
+	__be32 mode;
+	char path[];
+};
+
+static inline size_t sizeof_fuse_service_open_command(size_t pathlen)
+{
+	return sizeof(struct fuse_service_open_command) + pathlen + 1;
+}
+
+struct fuse_service_string_command {
+	struct fuse_service_packet p;
+	char value[];
+};
+
+static inline size_t sizeof_fuse_service_string_command(size_t len)
+{
+	return sizeof(struct fuse_service_string_command) + len + 1;
+}
+
+struct fuse_service_bye_command {
+	struct fuse_service_packet p;
+	__be32 error;
+};
+
+struct fuse_service_mount_command {
+	struct fuse_service_packet p;
+	__be32 flags;
+};
+
+int fuse_parse_cmdline_service(struct fuse_args *args,
+				 struct fuse_cmdline_opts *opts);
+
+#define FUSE_SERVICE_ARGV	"argv"
+#define FUSE_SERVICE_FUSEDEV	"fusedev"
+
+#endif /* FUSE_SERVICE_PRIV_H_ */
diff --git a/lib/fuse_i.h b/lib/fuse_i.h
index 0d0e637ae5a31c..5af8ed6a382a19 100644
--- a/lib/fuse_i.h
+++ b/lib/fuse_i.h
@@ -214,6 +214,11 @@ unsigned get_max_read(struct mount_opts *o);
 void fuse_kern_unmount(const char *mountpoint, int fd);
 int fuse_kern_mount(const char *mountpoint, struct mount_opts *mo);
 
+char *fuse_mountopts_fstype(const struct mount_opts *mo);
+char *fuse_mountopts_source(const struct mount_opts *mo, const char *devname);
+char *fuse_mountopts_kernel_opts(const struct mount_opts *mo);
+unsigned int fuse_mountopts_flags(const struct mount_opts *mo);
+
 int fuse_send_reply_iov_nofree(fuse_req_t req, int error, struct iovec *iov,
 			       int count);
 void fuse_free_req(fuse_req_t req);
diff --git a/util/mount_service.h b/util/mount_service.h
new file mode 100644
index 00000000000000..986a785bed3e74
--- /dev/null
+++ b/util/mount_service.h
@@ -0,0 +1,32 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2025 Oracle.
+  Author: Darrick J. Wong <djwong@kernel.org>
+
+  This program can be distributed under the terms of the GNU GPLv2.
+  See the file GPL2.txt.
+*/
+#ifndef MOUNT_SERVICE_H_
+#define MOUNT_SERVICE_H_
+
+/**
+ * Connect to a fuse service socket and try to mount the filesystem as
+ * specified with the CLI arguments.
+ *
+ * @argc argument count
+ * @argv vector of argument strings
+ * @return EXIT_SUCCESS for success, EXIT_FAILURE if mount fails
+ */
+int mount_service_main(int argc, char *argv[]);
+
+/**
+ * Return the fuse filesystem subtype from a full fuse filesystem type
+ * specification.  IOWs, fuse.Y -> Y; fuseblk.Z -> Z; or A -> A.  The returned
+ * pointer is within the caller's string.
+ *
+ * @param fstype full fuse filesystem type
+ * @return fuse subtype
+ */
+const char *mount_service_subtype(const char *fstype);
+
+#endif /* MOUNT_SERVICE_H_ */
diff --git a/doc/fuservicemount3.8 b/doc/fuservicemount3.8
new file mode 100644
index 00000000000000..e45d6a89c8b81a
--- /dev/null
+++ b/doc/fuservicemount3.8
@@ -0,0 +1,24 @@
+.TH fuservicemount3 "8"
+.SH NAME
+fuservicemount3 \- mount a FUSE filesystem that runs as a system socket service
+.SH SYNOPSIS
+.B fuservicemount3
+.B source
+.B mountpoint
+.BI -t " fstype"
+[
+.I options
+]
+.SH DESCRIPTION
+Mount a filesystem using a FUSE server that runs as a socket service.
+These servers can be contained using the platform's service management
+framework.
+.SH "AUTHORS"
+.LP
+The author of the fuse socket service code is Darrick J. Wong <djwong@kernel.org>.
+Debian GNU/Linux distribution.
+.SH SEE ALSO
+.BR fusermount3 (1)
+.BR fusermount (1)
+.BR mount (8)
+.BR fuse (4)
diff --git a/doc/meson.build b/doc/meson.build
index db3e0b26f71975..c105cf3471fdf4 100644
--- a/doc/meson.build
+++ b/doc/meson.build
@@ -2,3 +2,6 @@ if not platform.endswith('bsd') and platform != 'dragonfly'
   install_man('fusermount3.1', 'mount.fuse3.8')
 endif
 
+if private_cfg.get('HAVE_SERVICEMOUNT', false)
+  install_man('fuservicemount3.8')
+endif
diff --git a/include/meson.build b/include/meson.build
index bf671977a5a6a9..da51180f87eea2 100644
--- a/include/meson.build
+++ b/include/meson.build
@@ -1,4 +1,8 @@
 libfuse_headers = [ 'fuse.h', 'fuse_common.h', 'fuse_lowlevel.h',
 	            'fuse_opt.h', 'cuse_lowlevel.h', 'fuse_log.h' ]
 
+if private_cfg.get('HAVE_SERVICEMOUNT', false)
+  libfuse_headers += [ 'fuse_service.h' ]
+endif
+
 install_headers(libfuse_headers, subdir: 'fuse3')
diff --git a/lib/fuse_service.c b/lib/fuse_service.c
new file mode 100644
index 00000000000000..ab50f0017b255c
--- /dev/null
+++ b/lib/fuse_service.c
@@ -0,0 +1,764 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2025 Oracle.
+  Author: Darrick J. Wong <djwong@kernel.org>
+
+  Library functions to support fuse servers that can be run as "safe" systemd
+  containers.
+
+  This program can be distributed under the terms of the GNU LGPLv2.
+  See the file LGPL2.txt
+*/
+
+#define _GNU_SOURCE
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <systemd/sd-daemon.h>
+#include <arpa/inet.h>
+
+#include "fuse_config.h"
+#include "fuse_i.h"
+#include "fuse_service_priv.h"
+#include "fuse_service.h"
+
+struct fuse_service {
+	/* socket fd */
+	int sockfd;
+
+	/* /dev/fuse device */
+	int fusedevfd;
+
+	/* memfd for cli arguments */
+	int argvfd;
+};
+
+static int __recv_fd(int sockfd, struct fuse_service_requested_file *buf,
+		     ssize_t bufsize, int *fdp)
+{
+	struct iovec iov = {
+		.iov_base = buf,
+		.iov_len = bufsize,
+	};
+	union {
+		struct cmsghdr cmsghdr;
+		char control[CMSG_SPACE(sizeof (int))];
+	} cmsgu;
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+		.msg_control = cmsgu.control,
+		.msg_controllen = sizeof(cmsgu.control),
+	};
+	struct cmsghdr *cmsg;
+	ssize_t size;
+
+	memset(&cmsgu, 0, sizeof(cmsgu));
+
+	size = recvmsg(sockfd, &msg, MSG_TRUNC);
+	if (size < 0) {
+		perror("fuse: service file reply");
+		return -1;
+	}
+	if (size > bufsize ||
+	    size < offsetof(struct fuse_service_requested_file, path)) {
+		fprintf(stderr,
+ "fuse: wrong service file reply size %zd, expected %zd\n",
+			size, bufsize);
+		return -1;
+	}
+
+	cmsg = CMSG_FIRSTHDR(&msg);
+	if (!cmsg) {
+		/* no control message means mount.service sent us an error */
+		return 0;
+	}
+	if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
+		fprintf(stderr,
+ "fuse: wrong service file reply control data size %zd, expected %zd\n",
+			cmsg->cmsg_len, CMSG_LEN(sizeof(int)));
+		return -1;
+	}
+	if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
+		fprintf(stderr,
+ "fuse: wrong service file reply control data level %d type %d, expected %d and %d\n",
+			cmsg->cmsg_level, cmsg->cmsg_type, SOL_SOCKET,
+			SCM_RIGHTS);
+		return -1;
+	}
+
+	memcpy(fdp, (int *)CMSG_DATA(cmsg), sizeof(int));
+	return 0;
+}
+
+static int recv_requested_file(int sockfd, const char *path, int *fdp)
+{
+	struct fuse_service_requested_file *req;
+	const size_t req_sz = sizeof_fuse_service_requested_file(strlen(path));
+	int ret;
+
+	*fdp = -1;
+	req = calloc(1, req_sz + 1);
+	if (!req) {
+		perror("fuse: alloc service file reply");
+		return -1;
+	}
+
+	ret = __recv_fd(sockfd, req, req_sz, fdp);
+	if (ret)
+		goto out_req;
+
+	if (req->p.magic != ntohl(FUSE_SERVICE_OPEN_REPLY)) {
+		fprintf(stderr,
+ "fuse: service file reply contains wrong magic!\n");
+		ret = -1;
+		goto out_close;
+	}
+	if (strcmp(req->path, path)) {
+		fprintf(stderr,
+ "fuse: `%s': not the requested service file, got `%s'\n",
+			path, req->path);
+		ret = -1;
+		goto out_close;
+	}
+
+	if (req->error) {
+		errno = ntohl(req->error);
+		ret = -2;
+		goto out_req;
+	}
+
+	free(req);
+	return 0;
+
+out_close:
+	close(*fdp);
+	*fdp = -1;
+out_req:
+	free(req);
+	return ret;
+}
+
+int fuse_service_receive_file(struct fuse_service *sf, const char *path,
+			      int *fdp)
+{
+	return recv_requested_file(sf->sockfd, path, fdp);
+}
+
+int fuse_service_request_file(struct fuse_service *sf, const char *path,
+			      int flags, mode_t mode)
+{
+	struct iovec iov = {
+		.iov_len = sizeof_fuse_service_open_command(strlen(path)),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	struct fuse_service_open_command *cmd;
+	ssize_t size;
+	int ret;
+
+	cmd = calloc(1, iov.iov_len);
+	if (!cmd) {
+		perror("fuse: alloc service file request");
+		return -1;
+	}
+	cmd->p.magic = htonl(FUSE_SERVICE_OPEN_CMD);
+	cmd->flags = htonl(flags);
+	cmd->mode = htonl(mode);
+	strcpy(cmd->path, path);
+	iov.iov_base = cmd;
+
+	size = sendmsg(sf->sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+	if (size < 0) {
+		perror("fuse: request service file");
+		ret = -1;
+		goto out_free;
+	}
+
+	ret = 0;
+out_free:
+	free(cmd);
+	return ret;
+}
+
+int fuse_service_send_goodbye(struct fuse_service *sf, int error)
+{
+	struct fuse_service_bye_command c = {
+		.p.magic = htonl(FUSE_SERVICE_BYE_CMD),
+		.error = htonl(error),
+	};
+	struct iovec iov = {
+		.iov_base = &c,
+		.iov_len = sizeof(c),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	ssize_t size;
+
+	/* already gone? */
+	if (sf->sockfd < 0)
+		return 0;
+
+	size = sendmsg(sf->sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+	if (size < 0) {
+		perror("fuse: send service goodbye");
+		return -1;
+	}
+
+	shutdown(sf->sockfd, SHUT_RDWR);
+	close(sf->sockfd);
+	sf->sockfd = -1;
+	return 0;
+}
+
+static int find_socket_fd(void)
+{
+	struct stat statbuf;
+	char *listen_fds;
+	int nr_fds;
+	int ret;
+
+	listen_fds = getenv("LISTEN_FDS");
+	if (!listen_fds)
+		return -2;
+
+	nr_fds = atoi(listen_fds);
+	if (nr_fds != 1) {
+		fprintf(stderr,
+ "fuse: can only handle 1 service socket, got %d.\n",
+			nr_fds);
+		return -1;
+	}
+
+	ret = fstat(SD_LISTEN_FDS_START, &statbuf);
+	if (ret) {
+		perror("fuse: service socket");
+		return -1;
+	}
+
+	if (!S_ISSOCK(statbuf.st_mode)) {
+		fprintf(stderr,
+ "fuse: expected service fd %d to be a socket\n",
+				SD_LISTEN_FDS_START);
+		return -1;
+	}
+
+	return SD_LISTEN_FDS_START;
+}
+
+static int negotiate_hello(int sockfd)
+{
+	struct fuse_service_packet p = { };
+	struct iovec iov = {
+		.iov_base = &p,
+		.iov_len = sizeof(p),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	ssize_t size;
+
+	size = recvmsg(sockfd, &msg, MSG_TRUNC);
+	if (size < 0) {
+		perror("fuse: receive service hello");
+		return -1;
+	}
+	if (size != sizeof(p)) {
+		fprintf(stderr,
+ "fuse: wrong service hello size %zd, expected %zd\n",
+			size, sizeof(p));
+		return -1;
+	}
+
+	if (p.magic != ntohl(FUSE_SERVICE_HELLO_CMD)) {
+		fprintf(stderr,
+ "fuse: service server did not send hello command\n");
+		return -1;
+	}
+
+	p.magic = htonl(FUSE_SERVICE_HELLO_REPLY);
+	size = sendmsg(sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+	if (size < 0) {
+		perror("fuse: service hello reply");
+		return -1;
+	}
+
+	return 0;
+}
+
+int fuse_service_accept(struct fuse_service **sfp)
+{
+	struct fuse_service *sf;
+	int ret = 0;
+
+	*sfp = NULL;
+
+	sf = calloc(1, sizeof(struct fuse_service));
+	if (!sf) {
+		perror("fuse: service alloc");
+		return -1;
+	}
+
+	/* Find the socket that connects us to mount.service */
+	sf->sockfd = find_socket_fd();
+	if (sf->sockfd == -2) {
+		/* magic code that means no service configured */
+		ret = 0;
+		goto out_sf;
+	}
+	if (sf->sockfd < 0) {
+		ret = -1;
+		goto out_sf;
+	}
+
+	ret = negotiate_hello(sf->sockfd);
+	if (ret)
+		goto out_sf;
+
+	/* Receive the two critical sockets */
+	ret = recv_requested_file(sf->sockfd, FUSE_SERVICE_ARGV, &sf->argvfd);
+	if (ret == -2) {
+		perror("fuse: service mount options file");
+		goto out_sockfd;
+	}
+	if (ret < 0)
+		goto out_sockfd;
+
+	ret = recv_requested_file(sf->sockfd, FUSE_SERVICE_FUSEDEV,
+				  &sf->fusedevfd);
+	if (ret == -2) {
+		perror("fuse: service fuse device");
+		goto out_argvfd;
+	}
+	if (ret < 0)
+		goto out_argvfd;
+
+	*sfp = sf;
+	return 0;
+
+out_argvfd:
+	close(sf->argvfd);
+out_sockfd:
+	shutdown(sf->sockfd, SHUT_RDWR);
+	close(sf->sockfd);
+out_sf:
+	free(sf);
+	return ret;
+}
+
+int fuse_service_append_args(struct fuse_service *sf,
+			     struct fuse_args *existing_args)
+{
+	struct fuse_service_memfd_argv memfd_args = { };
+	struct fuse_args new_args = {
+		.allocated = 1,
+	};
+	char *str = NULL;
+	off_t memfd_pos = 0;
+	ssize_t received;
+	unsigned int i;
+	int ret;
+
+	/* Figure out how many arguments we're getting from the mount helper. */
+	received = pread(sf->argvfd, &memfd_args, sizeof(memfd_args), 0);
+	if (received < 0) {
+		perror("fuse: service args file");
+		return -1;
+	}
+	if (received < sizeof(memfd_args)) {
+		fprintf(stderr,
+ "fuse: service args file length unreadable\n");
+		return -1;
+	}
+	if (ntohl(memfd_args.magic) != FUSE_SERVICE_ARGS_MAGIC) {
+		fprintf(stderr, "fuse: service args file corrupt\n");
+		return -1;
+	}
+	memfd_args.magic = ntohl(memfd_args.magic);
+	memfd_args.argc = ntohl(memfd_args.argc);
+	memfd_pos += sizeof(memfd_args);
+
+	/* Allocate a new array of argv string pointers */
+	new_args.argv = calloc(memfd_args.argc + existing_args->argc,
+			       sizeof(char *));
+	if (!new_args.argv) {
+		perror("fuse: service new args");
+		return -1;
+	}
+
+	/*
+	 * Copy the fuse server's CLI arguments.  We'll leave new_args.argv[0]
+	 * unset for now, because we'll set it in the next step with the fstype
+	 * that the mount helper sent us.
+	 */
+	new_args.argc++;
+	for (i = 1; i < existing_args->argc; i++) {
+		if (existing_args->allocated) {
+			new_args.argv[new_args.argc] = existing_args->argv[i];
+			existing_args->argv[i] = NULL;
+		} else {
+			new_args.argv[new_args.argc] =
+						strdup(existing_args->argv[i]);
+			if (!new_args.argv[new_args.argc]) {
+				perror("fuse: service duplicate existing args");
+				ret = -1;
+				goto out_new_args;
+			}
+		}
+
+		new_args.argc++;
+	}
+
+	/* Copy the rest of the arguments from the helper */
+	for (i = 0; i < memfd_args.argc; i++) {
+		struct fuse_service_memfd_arg memfd_arg = { };
+
+		/* Read argv iovec */
+		received = pread(sf->argvfd, &memfd_arg, sizeof(memfd_arg),
+				 memfd_pos);
+		if (received < 0) {
+			perror("fuse: service args file iovec read");
+			ret = -1;
+			goto out_new_args;
+		}
+		if (received < sizeof(struct fuse_service_memfd_arg)) {
+			fprintf(stderr,
+ "fuse: service args file argv[%u] iovec short read %zd",
+				i, received);
+			ret = -1;
+			goto out_new_args;
+		}
+		memfd_arg.pos = ntohl(memfd_arg.pos);
+		memfd_arg.len = ntohl(memfd_arg.len);
+		memfd_pos += sizeof(memfd_arg);
+
+		/* read arg string from file */
+		str = calloc(1, memfd_arg.len + 1);
+		if (!str) {
+			perror("fuse: service arg alloc");
+			ret = -1;
+			goto out_new_args;
+		}
+
+		received = pread(sf->argvfd, str, memfd_arg.len, memfd_arg.pos);
+		if (received < 0) {
+			perror("fuse: service args file read");
+			ret = -1;
+			goto out_str;
+		}
+		if (received < memfd_arg.len) {
+			fprintf(stderr,
+ "fuse: service args file argv[%u] short read %zd",
+				i, received);
+			ret = -1;
+			goto out_str;
+		}
+
+		/* move string into the args structure */
+		if (i == 0) {
+			/* the first argument is the fs type */
+			new_args.argv[0] = str;
+		} else {
+			new_args.argv[new_args.argc] = str;
+			new_args.argc++;
+		}
+		str = NULL;
+	}
+
+	/* drop existing args, move new args to existing args */
+	fuse_opt_free_args(existing_args);
+	memcpy(existing_args, &new_args, sizeof(*existing_args));
+
+	close(sf->argvfd);
+	sf->argvfd = -1;
+
+	return 0;
+
+out_str:
+	free(str);
+out_new_args:
+	fuse_opt_free_args(&new_args);
+	return ret;
+}
+
+int fuse_service_take_fusedev(struct fuse_service *sfp)
+{
+	int ret = sfp->fusedevfd;
+
+	sfp->fusedevfd = -1;
+	return ret;
+}
+
+int fuse_service_finish_file_requests(struct fuse_service *sf)
+{
+#ifdef SO_PASSRIGHTS
+	int zero = 0;
+
+	/* don't let a malicious mount helper send us more fds */
+	return setsockopt(sf->sockfd, SOL_SOCKET, SO_PASSRIGHTS, &zero,
+			  sizeof(zero));
+#else
+	/* shut up gcc */
+	sf = sf;
+	return 0;
+#endif
+}
+
+static int send_string(struct fuse_service *sf, uint32_t command,
+		       const char *value, int *error)
+{
+	struct fuse_service_simple_reply reply = { };
+	struct iovec iov = {
+		.iov_len = sizeof_fuse_service_string_command(strlen(value)),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	struct fuse_service_string_command *cmd;
+	ssize_t size;
+
+	cmd = malloc(iov.iov_len);
+	if (!cmd) {
+		perror("fuse: alloc service string send");
+		return -1;
+	}
+	cmd->p.magic = ntohl(command);
+	strcpy(cmd->value, value);
+	iov.iov_base = cmd;
+
+	size = sendmsg(sf->sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+	if (size < 0) {
+		perror("fuse: send service string");
+		return -1;
+	}
+	free(cmd);
+
+	iov.iov_base = &reply;
+	iov.iov_len = sizeof(reply);
+	size = recvmsg(sf->sockfd, &msg, MSG_TRUNC);
+	if (size < 0) {
+		perror("fuse: service string reply");
+		return -1;
+	}
+	if (size != sizeof(reply)) {
+		fprintf(stderr,
+ "fuse: wrong service string reply size %zd, expected %zd\n",
+			size, sizeof(reply));
+		return -1;
+	}
+
+	if (ntohl(reply.p.magic) != FUSE_SERVICE_SIMPLE_REPLY) {
+		fprintf(stderr,
+ "fuse: service string reply contains wrong magic!\n");
+		return -1;
+	}
+
+	*error = ntohl(reply.error);
+	return 0;
+}
+
+static int send_mount(struct fuse_service *sf, unsigned int flags, int *error)
+{
+	struct fuse_service_simple_reply reply = { };
+	struct fuse_service_mount_command c = {
+		.p.magic = htonl(FUSE_SERVICE_MOUNT_CMD),
+		.flags = htonl(flags),
+	};
+	struct iovec iov = {
+		.iov_base = &c,
+		.iov_len = sizeof(c),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	ssize_t size;
+
+	size = sendmsg(sf->sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+	if (size < 0) {
+		perror("fuse: send service mount command");
+		return -1;
+	}
+
+	iov.iov_base = &reply;
+	iov.iov_len = sizeof(reply);
+	size = recvmsg(sf->sockfd, &msg, MSG_TRUNC);
+	if (size < 0) {
+		perror("fuse: service mount reply");
+		return -1;
+	}
+	if (size != sizeof(reply)) {
+		fprintf(stderr,
+ "fuse: wrong service mount reply size %zd, expected %zd\n",
+			size, sizeof(reply));
+		return -1;
+	}
+
+	if (ntohl(reply.p.magic) != FUSE_SERVICE_SIMPLE_REPLY) {
+		fprintf(stderr,
+ "fuse: service mount reply contains wrong magic!\n");
+		return -1;
+	}
+
+	*error = ntohl(reply.error);
+	return 0;
+}
+
+int fuse_service_mount(struct fuse_service *sf, struct fuse_session *se,
+		       const char *mountpoint)
+{
+	char *fstype = fuse_mountopts_fstype(se->mo);
+	char *source = fuse_mountopts_source(se->mo, "???");
+	char *mntopts = fuse_mountopts_kernel_opts(se->mo);
+	int ret;
+	int error;
+
+	if (!fstype || !source) {
+		fprintf(stderr, "fuse: cannot allocate service strings\n");
+		ret = -1;
+		goto out_strings;
+	}
+
+	ret = send_string(sf, FUSE_SERVICE_FSOPEN_CMD, fstype, &error);
+	if (ret)
+		goto out_strings;
+	if (error) {
+		fprintf(stderr, "fuse: service fsopen: %s\n",
+			strerror(error));
+		ret = -1;
+		goto out_strings;
+	}
+
+	ret = send_string(sf, FUSE_SERVICE_SOURCE_CMD, source, &error);
+	if (ret)
+		goto out_strings;
+	if (error) {
+		fprintf(stderr, "fuse: service fs source: %s\n",
+			strerror(error));
+		ret = -1;
+		goto out_strings;
+	}
+
+	ret = send_string(sf, FUSE_SERVICE_MNTPT_CMD, mountpoint, &error);
+	if (ret)
+		goto out_strings;
+	if (error) {
+		fprintf(stderr, "fuse: service fs mountpoint: %s\n",
+			strerror(error));
+		ret = -1;
+		goto out_strings;
+	}
+
+	if (mntopts) {
+		ret = send_string(sf, FUSE_SERVICE_MNTOPTS_CMD, mntopts,
+				  &error);
+		if (ret)
+			goto out_strings;
+		if (error) {
+			fprintf(stderr,
+ "fuse: service fs mount options: %s\n",
+				strerror(error));
+			ret = -1;
+			goto out_strings;
+		}
+	}
+
+	ret = send_mount(sf, fuse_mountopts_flags(se->mo), &error);
+	if (ret)
+		goto out_strings;
+	if (error) {
+		fprintf(stderr, "fuse: service mount: %s\n", strerror(error));
+		ret = -1;
+		goto out_strings;
+	}
+
+out_strings:
+	free(mntopts);
+	free(source);
+	free(fstype);
+	return ret;
+}
+
+void fuse_service_release(struct fuse_service *sf)
+{
+	close(sf->fusedevfd);
+	sf->fusedevfd = -1;
+	close(sf->argvfd);
+	sf->argvfd = -1;
+	shutdown(sf->sockfd, SHUT_RDWR);
+	close(sf->sockfd);
+	sf->sockfd = -1;
+}
+
+void fuse_service_destroy(struct fuse_service **sfp)
+{
+	struct fuse_service *sf = *sfp;
+
+	if (sf) {
+		fuse_service_release(*sfp);
+		free(sf);
+	}
+
+	*sfp = NULL;
+}
+
+char *fuse_service_cmdline(int argc, char *argv[], struct fuse_args *args)
+{
+	char *p, *dst;
+	size_t len = 1;
+	ssize_t ret;
+	char *argv0;
+	unsigned int i;
+
+	/* Try to preserve argv[0] */
+	if (argc > 0)
+		argv0 = argv[0];
+	else if (args->argc > 0)
+		argv0 = args->argv[0];
+	else
+		return NULL;
+
+	/* Pick up the alleged fstype from args->argv[0] */
+	if (args->argc == 0)
+		return NULL;
+
+	len += strlen(argv0) + 1;
+	len += 3; /* " -t" */
+	for (i = 0; i < args->argc; i++) {
+		len += strlen(args->argv[i]) + 1;
+	}
+
+	p = malloc(len);
+	if (!p)
+		return NULL;
+	dst = p;
+
+	/* Format: argv0 -t alleged_fstype [all other options...] */
+	ret = sprintf(dst, "%s -t", argv0);
+	dst += ret;
+	for (i = 0; i < args->argc; i++) {
+		ret = sprintf(dst, " %s", args->argv[i]);
+		dst += ret;
+	}
+
+	return p;
+}
+
+int fuse_service_parse_cmdline_opts(struct fuse_args *args,
+				    struct fuse_cmdline_opts *opts)
+{
+	return fuse_parse_cmdline_service(args, opts);
+}
diff --git a/lib/fuse_service_stub.c b/lib/fuse_service_stub.c
new file mode 100644
index 00000000000000..b65a711d5a9946
--- /dev/null
+++ b/lib/fuse_service_stub.c
@@ -0,0 +1,90 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2025 Oracle.
+  Author: Darrick J. Wong <djwong@kernel.org>
+
+  Stub functions for platforms where we cannot have fuse servers run as "safe"
+  systemd containers.
+
+  This program can be distributed under the terms of the GNU LGPLv2.
+  See the file LGPL2.txt
+*/
+
+/* shut up gcc */
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+
+#define _GNU_SOURCE
+#include <errno.h>
+
+#include "fuse_config.h"
+#include "fuse_i.h"
+#include "fuse_service_priv.h"
+#include "fuse_service.h"
+
+int fuse_service_receive_file(struct fuse_service *sf, const char *path,
+			      int *fdp)
+{
+	errno = EOPNOTSUPP;
+	return -1;
+}
+
+int fuse_service_request_file(struct fuse_service *sf, const char *path,
+			      int flags, mode_t mode)
+{
+	errno = EOPNOTSUPP;
+	return -1;
+}
+
+int fuse_service_send_goodbye(struct fuse_service *sf, int error)
+{
+	errno = EOPNOTSUPP;
+	return -1;
+}
+
+int fuse_service_accept(struct fuse_service **sfp)
+{
+	*sfp = NULL;
+	errno = EOPNOTSUPP;
+	return -1;
+}
+
+int fuse_service_append_args(struct fuse_service *sf,
+			     struct fuse_args *existing_args)
+{
+	errno = EOPNOTSUPP;
+	return -1;
+}
+
+int fuse_service_take_fusedev(struct fuse_service *sfp)
+{
+	return -1;
+}
+
+int fuse_service_finish_file_requests(struct fuse_service *sf)
+{
+	errno = EOPNOTSUPP;
+	return -1;
+}
+
+int fuse_service_mount(struct fuse_service *sf, struct fuse_session *se,
+		       const char *mountpoint)
+{
+	errno = EOPNOTSUPP;
+	return -1;
+}
+
+void fuse_service_release(struct fuse_service *sf)
+{
+}
+
+void fuse_service_destroy(struct fuse_service **sfp)
+{
+	*sfp = NULL;
+}
+
+int fuse_service_parse_cmdline(struct fuse_args *args,
+			       struct fuse_cmdline_opts *opts)
+{
+	errno = EOPNOTSUPP;
+	return -1;
+}
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index db95fc6e7b1b41..335e18063bab00 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -240,6 +240,19 @@ FUSE_3.99 {
 		fuse_lowlevel_notify_iomap_inval;
 		fuse_fs_iomap_upsert;
 		fuse_fs_iomap_inval;
+
+		fuse_service_accept;
+		fuse_service_append_args;
+		fuse_service_destroy;
+		fuse_service_finish_file_requests;
+		fuse_service_mount;
+		fuse_service_cmdline;
+		fuse_service_parse_cmdline_opts;
+		fuse_service_receive_file;
+		fuse_service_release;
+		fuse_service_request_file;
+		fuse_service_send_goodbye;
+		fuse_service_take_fusedev;
 } FUSE_3.18;
 
 # Local Variables:
diff --git a/lib/helper.c b/lib/helper.c
index 5c13b93a473181..3b57788621d902 100644
--- a/lib/helper.c
+++ b/lib/helper.c
@@ -26,6 +26,11 @@
 #include <errno.h>
 #include <sys/param.h>
 
+#ifdef HAVE_SERVICEMOUNT
+# include <linux/types.h>
+# include "fuse_service_priv.h"
+#endif
+
 #define FUSE_HELPER_OPT(t, p) \
 	{ t, offsetof(struct fuse_cmdline_opts, p), 1 }
 
@@ -174,6 +179,29 @@ static int fuse_helper_opt_proc(void *data, const char *arg, int key,
 	}
 }
 
+#ifdef HAVE_SERVICEMOUNT
+static int fuse_helper_opt_proc_service(void *data, const char *arg, int key,
+					struct fuse_args *outargs)
+{
+	(void) outargs;
+	struct fuse_cmdline_opts *opts = data;
+
+	switch (key) {
+	case FUSE_OPT_KEY_NONOPT:
+		if (!opts->mountpoint) {
+			return fuse_opt_add_opt(&opts->mountpoint, arg);
+		} else {
+			fuse_log(FUSE_LOG_ERR, "fuse: invalid argument `%s'\n", arg);
+			return -1;
+		}
+
+	default:
+		/* Pass through unknown options */
+		return 1;
+	}
+}
+#endif
+
 /* Under FreeBSD, there is no subtype option so this
    function actually sets the fsname */
 static int add_default_subtype(const char *progname, struct fuse_args *args)
@@ -228,6 +256,31 @@ int fuse_parse_cmdline_312(struct fuse_args *args,
 	return 0;
 }
 
+#ifdef HAVE_SERVICEMOUNT
+int fuse_parse_cmdline_service(struct fuse_args *args,
+			       struct fuse_cmdline_opts *opts)
+{
+	memset(opts, 0, sizeof(struct fuse_cmdline_opts));
+
+	opts->max_idle_threads = UINT_MAX; /* new default in fuse version 3.12 */
+	opts->max_threads = 10;
+
+	if (fuse_opt_parse(args, opts, fuse_helper_opts,
+			   fuse_helper_opt_proc_service) == -1)
+		return -1;
+
+	/* *Linux*: if neither -o subtype nor -o fsname are specified,
+	   set subtype to program's basename.
+	   *FreeBSD*: if fsname is not specified, set to program's
+	   basename. */
+	if (!opts->nodefault_subtype)
+		if (add_default_subtype(args->argv[0], args) == -1)
+			return -1;
+
+	return 0;
+}
+#endif
+
 /**
  * struct fuse_cmdline_opts got extended in libfuse-3.12
  */
diff --git a/lib/meson.build b/lib/meson.build
index 8efe71abfabc9e..83993d2f0e529c 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -10,6 +10,12 @@ else
    libfuse_sources += [ 'mount_bsd.c' ]
 endif
 
+if private_cfg.get('HAVE_SERVICEMOUNT', false)
+  libfuse_sources += [ 'fuse_service.c' ]
+else
+  libfuse_sources += [ 'fuse_service_stub.c' ]
+endif
+
 deps = [ thread_dep ]
 if private_cfg.get('HAVE_ICONV')
    libfuse_sources += [ 'modules/iconv.c' ]
@@ -54,13 +60,19 @@ libfuse = library('fuse3',
                   link_args: ['-Wl,--version-script,' + meson.current_source_dir()
                               + '/fuse_versionscript' ])
 
+vars = []
+if private_cfg.get('HAVE_SERVICEMOUNT', false)
+  service_socket_dir = private_cfg.get_unquoted('FUSE_SERVICE_SOCKET_DIR', '')
+  vars += ['service_socket_dir=' + service_socket_dir]
+endif
 pkg = import('pkgconfig')
 pkg.generate(libraries: [ libfuse, '-lpthread' ],
              libraries_private: '-ldl',
              version: meson.project_version(),
              name: 'fuse3',
              description: 'Filesystem in Userspace',
-             subdirs: 'fuse3')
+             subdirs: 'fuse3',
+             variables: vars)
 
 libfuse_dep = declare_dependency(include_directories: include_dirs,
                                  link_with: libfuse, dependencies: deps)
diff --git a/lib/mount.c b/lib/mount.c
index 01d473902d50d7..a116fe35eaa5ba 100644
--- a/lib/mount.c
+++ b/lib/mount.c
@@ -562,24 +562,13 @@ static int fuse_mount_sys(const char *mnt, struct mount_opts *mo,
 	if (res == -1)
 		goto out_close;
 
-	source = malloc((mo->fsname ? strlen(mo->fsname) : 0) +
-			(mo->subtype ? strlen(mo->subtype) : 0) +
-			strlen(devname) + 32);
-
-	type = malloc((mo->subtype ? strlen(mo->subtype) : 0) + 32);
+	type = fuse_mountopts_fstype(mo);
+	source = fuse_mountopts_source(mo, devname);
 	if (!type || !source) {
 		fuse_log(FUSE_LOG_ERR, "fuse: failed to allocate memory\n");
 		goto out_close;
 	}
 
-	strcpy(type, mo->blkdev ? "fuseblk" : "fuse");
-	if (mo->subtype) {
-		strcat(type, ".");
-		strcat(type, mo->subtype);
-	}
-	strcpy(source,
-	       mo->fsname ? mo->fsname : (mo->subtype ? mo->subtype : devname));
-
 	res = mount(source, mnt, type, mo->flags, mo->kernel_opts);
 	if (res == -1 && errno == ENODEV && mo->subtype) {
 		/* Probably missing subtype support */
@@ -690,6 +679,48 @@ void destroy_mount_opts(struct mount_opts *mo)
 	free(mo);
 }
 
+char *fuse_mountopts_fstype(const struct mount_opts *mo)
+{
+	char *type = malloc((mo->subtype ? strlen(mo->subtype) : 0) + 32);
+
+	if (!type)
+		return NULL;
+
+	strcpy(type, mo->blkdev ? "fuseblk" : "fuse");
+	if (mo->subtype) {
+		strcat(type, ".");
+		strcat(type, mo->subtype);
+	}
+
+	return type;
+}
+
+char *fuse_mountopts_source(const struct mount_opts *mo, const char *devname)
+{
+	char *source = malloc((mo->fsname ? strlen(mo->fsname) : 0) +
+			(mo->subtype ? strlen(mo->subtype) : 0) +
+			strlen(devname) + 32);
+
+	if (!source)
+		return NULL;
+
+	strcpy(source,
+	       mo->fsname ? mo->fsname : (mo->subtype ? mo->subtype : devname));
+
+	return source;
+}
+
+char *fuse_mountopts_kernel_opts(const struct mount_opts *mo)
+{
+	if (mo->kernel_opts)
+		return strdup(mo->kernel_opts);
+	return NULL;
+}
+
+unsigned int fuse_mountopts_flags(const struct mount_opts *mo)
+{
+	return mo->flags;
+}
 
 int fuse_kern_mount(const char *mountpoint, struct mount_opts *mo)
 {
diff --git a/meson.build b/meson.build
index 7214d24705c7fb..9b7a0a319a91a3 100644
--- a/meson.build
+++ b/meson.build
@@ -69,6 +69,11 @@ args_default = [ '-D_GNU_SOURCE' ]
 #
 private_cfg = configuration_data()
 private_cfg.set_quoted('PACKAGE_VERSION', meson.project_version())
+service_socket_dir = get_option('service-socket-dir')
+if service_socket_dir == ''
+  service_socket_dir = '/run/filesystems'
+endif
+private_cfg.set_quoted('FUSE_SERVICE_SOCKET_DIR', service_socket_dir)
 
 # Test for presence of some functions
 test_funcs = [ 'fork', 'fstatat', 'openat', 'readlinkat', 'pipe2',
@@ -163,6 +168,37 @@ if get_option('enable-io-uring') and liburing.found() and libnuma.found()
    endif
 endif
 
+# Check for systemd support
+systemd_system_unit_dir = get_option('systemdsystemunitdir')
+if systemd_system_unit_dir == ''
+  systemd = dependency('systemd', required: false)
+  if systemd.found()
+     systemd_system_unit_dir = systemd.get_variable(pkgconfig: 'systemd_system_unit_dir')
+  endif
+endif
+
+if systemd_system_unit_dir == ''
+  warning('could not determine systemdsystemunitdir, systemd stuff will not be installed')
+else
+  private_cfg.set_quoted('SYSTEMD_SYSTEM_UNIT_DIR', systemd_system_unit_dir)
+  private_cfg.set('HAVE_SYSTEMD', true)
+endif
+
+# Check for libc SCM_RIGHTS support (aka Linux)
+code = '''
+#include <sys/socket.h>
+int main(void) {
+    int moo = SCM_RIGHTS;
+    return moo;
+}'''
+if cc.links(code, name: 'libc SCM_RIGHTS support')
+  private_cfg.set('HAVE_SCM_RIGHTS', true)
+endif
+
+if private_cfg.get('HAVE_SCM_RIGHTS', false) and private_cfg.get('HAVE_SYSTEMD', false)
+  private_cfg.set('HAVE_SERVICEMOUNT', true)
+endif
+
 #
 # Compiler configuration
 #
diff --git a/meson_options.txt b/meson_options.txt
index c1f8fe69467184..95655a0d64895c 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -27,3 +27,9 @@ option('enable-usdt', type : 'boolean', value : false,
 
 option('enable-io-uring', type: 'boolean', value: true,
        description: 'Enable fuse-over-io-uring support')
+
+option('service-socket-dir', type : 'string', value : '',
+       description: 'Where to install fuse server sockets (if empty, /run/filesystems)')
+
+option('systemdsystemunitdir', type : 'string', value : '',
+       description: 'Where to install systemd unit files (if empty, query pkg-config(1))')
diff --git a/util/fuservicemount.c b/util/fuservicemount.c
new file mode 100644
index 00000000000000..c54d5b0767f760
--- /dev/null
+++ b/util/fuservicemount.c
@@ -0,0 +1,18 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2025 Oracle.
+  Author: Darrick J. Wong <djwong@kernel.org>
+
+  This program can be distributed under the terms of the GNU GPLv2.
+  See the file GPL2.txt.
+*/
+/* This program does the mounting of FUSE filesystems that run in systemd */
+
+#define _GNU_SOURCE
+#include "fuse_config.h"
+#include "mount_service.h"
+
+int main(int argc, char *argv[])
+{
+	return mount_service_main(argc, argv);
+}
diff --git a/util/meson.build b/util/meson.build
index 0e4b1cce95377e..68d8bb11f92955 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -6,6 +6,15 @@ executable('fusermount3', ['fusermount.c', '../lib/mount_util.c', '../lib/util.c
            install_dir: get_option('bindir'),
            c_args: '-DFUSE_CONF="@0@"'.format(fuseconf_path))
 
+if private_cfg.get('HAVE_SERVICEMOUNT', false)
+  executable('fuservicemount3', ['mount_service.c', 'fuservicemount.c'],
+             include_directories: include_dirs,
+             link_with: [ libfuse ],
+             install: true,
+             install_dir: get_option('sbindir'),
+             c_args: '-DFUSE_USE_VERSION=317')
+endif
+
 executable('mount.fuse3', ['mount.fuse.c'],
            include_directories: include_dirs,
            link_with: [ libfuse ],
diff --git a/util/mount_service.c b/util/mount_service.c
new file mode 100644
index 00000000000000..46d368d0cba922
--- /dev/null
+++ b/util/mount_service.c
@@ -0,0 +1,962 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2025 Oracle.
+  Author: Darrick J. Wong <djwong@kernel.org>
+
+  This program can be distributed under the terms of the GNU GPLv2.
+  See the file GPL2.txt.
+*/
+/* This program does the mounting of FUSE filesystems that run in systemd */
+
+#define _GNU_SOURCE
+#include <stdint.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/mount.h>
+#include <stdbool.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <arpa/inet.h>
+
+#include "fuse_config.h"
+#include "mount_util.h"
+#include "util.h"
+#include "fuse_i.h"
+#include "fuse_service_priv.h"
+#include "mount_service.h"
+
+#define FUSE_KERN_DEVICE_ENV	"FUSE_KERN_DEVICE"
+#define FUSE_DEV		"/dev/fuse"
+
+struct mount_service {
+	/* alleged fuse subtype based on -t cli argument */
+	const char *subtype;
+
+	/* full fuse filesystem type we give to mount() */
+	char *fstype;
+
+	/* source argument to mount() */
+	char *source;
+
+	/* target argument (aka mountpoint) to mount() */
+	char *mountpoint;
+
+	/* mount options */
+	char *mntopts;
+
+	/* socket fd */
+	int sockfd;
+
+	/* /dev/fuse device */
+	int fusedevfd;
+
+	/* memfd for cli arguments */
+	int argvfd;
+
+	/* fd for fsopen */
+	int fsopenfd;
+};
+
+/* Filter out the subtype of the filesystem (e.g. fuse.Y -> Y) */
+const char *mount_service_subtype(const char *fstype)
+{
+	char *period = strrchr(fstype, '.');
+	if (period)
+		return period + 1;
+
+	return fstype;
+}
+
+static int mount_service_init(struct mount_service *mo, int argc,
+			      char *argv[])
+{
+	char *fstype = NULL;
+	int i;
+
+	mo->sockfd = -1;
+	mo->fsopenfd = -1;
+
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argv[i], "-t") && i + 1 < argc) {
+			fstype = argv[i + 1];
+			break;
+		}
+	}
+	if (!fstype)
+		return -1;
+
+	mo->subtype = mount_service_subtype(fstype);
+	return 0;
+}
+
+static int mount_service_connect(struct mount_service *mo)
+{
+	struct sockaddr_un name = {
+		.sun_family = AF_UNIX,
+	};
+	int sockfd;
+	ssize_t written;
+	int ret;
+
+	written = snprintf(name.sun_path, sizeof(name.sun_path),
+			FUSE_SERVICE_SOCKET_DIR "/%s", mo->subtype);
+	if (written > sizeof(name.sun_path)) {
+		fprintf(stderr,
+ "mount.service: filesystem type name (\"%s\") is too long.\n",
+			mo->subtype);
+		return -1;
+	}
+
+	sockfd = socket(AF_UNIX, SOCK_SEQPACKET, 0);
+	if (sockfd < 0) {
+		fprintf(stderr,
+ "mount.service: opening %s service socket: %s\n", mo->subtype,
+			strerror(errno));
+		return -1;
+	}
+
+	ret = connect(sockfd, (const struct sockaddr *)&name, sizeof(name));
+	if (ret) {
+		if (errno == ENOENT)
+			fprintf(stderr,
+ "mount.service: no safe filesystem driver for %s available.\n",
+				mo->subtype);
+		else
+			perror(name.sun_path);
+		goto out;
+	}
+
+#ifdef SO_PASSRIGHTS
+	{
+		int zero = 0;
+
+		/* don't let a malicious fuse server send us more fds */
+		setsockopt(sockfd, SOL_SOCKET, SO_PASSRIGHTS, &zero,
+			   sizeof(zero));
+	}
+#endif
+
+	mo->sockfd = sockfd;
+	return 0;
+out:
+	close(sockfd);
+	return -1;
+}
+
+static int mount_service_send_hello(struct mount_service *mo)
+{
+	struct fuse_service_packet p = {
+		.magic = htonl(FUSE_SERVICE_HELLO_CMD),
+	};
+	struct iovec iov = {
+		.iov_base = &p,
+		.iov_len = sizeof(p),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	ssize_t size;
+
+	size = sendmsg(mo->sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+	if (size < 0) {
+		perror("mount.service: send hello");
+		return -1;
+	}
+
+	size = recvmsg(mo->sockfd, &msg, MSG_TRUNC);
+	if (size < 0) {
+		perror("mount.service: hello reply");
+		return -1;
+	}
+	if (size != sizeof(p)) {
+		fprintf(stderr,
+ "mount.service: wrong hello reply size %zd, expected %zd\n",
+			size, sizeof(p));
+		return -1;
+	}
+
+	if (p.magic != ntohl(FUSE_SERVICE_HELLO_REPLY)) {
+		fprintf(stderr,
+ "mount.service: %s service server did not reply to hello\n",
+			mo->subtype);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int mount_service_capture_arg(struct mount_service *mo,
+				     struct fuse_service_memfd_argv *args,
+				     const char *string, off_t *array_pos,
+				     off_t *string_pos)
+{
+	const size_t string_len = strlen(string) + 1;
+	struct fuse_service_memfd_arg arg = {
+		.pos = htonl(*string_pos),
+		.len = htonl(string_len),
+	};
+	ssize_t written;
+
+	written = pwrite(mo->argvfd, string, string_len, *string_pos);
+	if (written < 0) {
+		perror("mount.service: memfd argv write");
+		return -1;
+	}
+	if (written < string_len) {
+		fprintf(stderr, "mount.service: memfd argv[%u] write %zd\n",
+			args->argc, written);
+		return -1;
+	}
+
+	written = pwrite(mo->argvfd, &arg, sizeof(arg), *array_pos);
+	if (written < 0) {
+		perror("mount.service: memfd arg write");
+		return -1;
+	}
+	if (written < sizeof(arg)) {
+		fprintf(stderr, "mount.service: memfd arg[%u] write %zd\n",
+			args->argc, written);
+		return -1;
+	}
+
+	args->argc++;
+	*string_pos += string_len;
+	*array_pos += sizeof(arg);
+
+	return 0;
+}
+
+static int mount_service_capture_args(struct mount_service *mo, int argc,
+				      char *argv[])
+{
+	struct fuse_service_memfd_argv args = {
+		.magic = htonl(FUSE_SERVICE_ARGS_MAGIC),
+	};
+	off_t array_pos = sizeof(struct fuse_service_memfd_argv);
+	off_t string_pos = array_pos +
+			(argc * sizeof(struct fuse_service_memfd_arg));
+	ssize_t written;
+	int i;
+	int ret;
+
+	if (argc < 0) {
+		fprintf(stderr, "mount.service: argc cannot be negative\n");
+		return -1;
+	}
+
+	/*
+	 * Create the memfd in which we'll stash arguments, and set the write
+	 * pointer for the names.
+	 */
+	mo->argvfd = memfd_create("mount.service args", MFD_CLOEXEC);
+	if (mo->argvfd < 0) {
+		perror("mount.service: argvfd create");
+		return -1;
+	}
+
+	/*
+	 * Write the alleged subtype as if it were argv[0], then write the rest
+	 * of the argv arguments.
+	 */
+	ret = mount_service_capture_arg(mo, &args, mo->subtype, &array_pos,
+					&string_pos);
+	if (ret)
+		return ret;
+
+	for (i = 1; i < argc; i++) {
+		/* skip the -t(ype) argument */
+		if (!strcmp(argv[i], "-t")) {
+			i++;
+			continue;
+		}
+
+		ret = mount_service_capture_arg(mo, &args, argv[i],
+						&array_pos, &string_pos);
+		if (ret)
+			return ret;
+	}
+
+	/* Now write the header */
+	args.argc = htonl(args.argc);
+	written = pwrite(mo->argvfd, &args, sizeof(args), 0);
+	if (written < 0) {
+		perror("mount.service: memfd argv write");
+		return -1;
+	}
+	if (written < sizeof(args)) {
+		fprintf(stderr, "mount.service: memfd argv wrote %zd\n",
+			written);
+		return -1;
+	}
+
+	return 0;
+}
+
+static ssize_t __send_fd(int sockfd, struct fuse_service_requested_file *req,
+			 size_t req_sz, int fd)
+{
+	union {
+		struct cmsghdr cmsghdr;
+		char control[CMSG_SPACE(sizeof(int))];
+	} cmsgu;
+	struct iovec iov = {
+		.iov_base = req,
+		.iov_len = req_sz,
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+		.msg_control = cmsgu.control,
+		.msg_controllen = sizeof(cmsgu.control),
+	};
+	struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+
+	memset(&cmsgu, 0, sizeof(cmsgu));
+	cmsg->cmsg_len = CMSG_LEN(sizeof (int));
+	cmsg->cmsg_level = SOL_SOCKET;
+	cmsg->cmsg_type = SCM_RIGHTS;
+
+	*((int *)CMSG_DATA(cmsg)) = fd;
+
+	return sendmsg(sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+}
+
+static int mount_service_send_file(struct mount_service *mo,
+				   const char *path, int fd)
+{
+	struct fuse_service_requested_file *req;
+	const size_t req_sz =
+			sizeof_fuse_service_requested_file(strlen(path));
+	ssize_t written;
+	int ret = 0;
+
+	req = malloc(req_sz);
+	if (!req) {
+		perror("mount.service: alloc send file reply");
+		return -1;
+	}
+	req->p.magic = htonl(FUSE_SERVICE_OPEN_REPLY);
+	req->error = 0;
+	strcpy(req->path, path);
+
+	written = __send_fd(mo->sockfd, req, req_sz, fd);
+	if (written < 0) {
+		perror("mount.service: send file reply");
+		ret = -1;
+	}
+
+	free(req);
+	return ret;
+}
+
+static ssize_t __send_packet(int sockfd, void *buf, ssize_t buflen)
+{
+	struct iovec iov = {
+		.iov_base = buf,
+		.iov_len = buflen,
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+
+	return sendmsg(sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+}
+
+static int mount_service_send_file_error(struct mount_service *mo, int error,
+					 const char *path)
+{
+	struct fuse_service_requested_file *req;
+	const size_t req_sz =
+			sizeof_fuse_service_requested_file(strlen(path));
+	ssize_t written;
+	int ret = 0;
+
+	req = malloc(req_sz);
+	if (!req) {
+		perror("mount.service: alloc send file error");
+		return -1;
+	}
+	req->p.magic = htonl(FUSE_SERVICE_OPEN_REPLY);
+	req->error = htonl(error);
+	strcpy(req->path, path);
+
+	written = __send_packet(mo->sockfd, req, req_sz);
+	if (written < 0) {
+		perror("mount.service: send file error");
+		ret = -1;
+	}
+
+	free(req);
+	return ret;
+}
+
+static int mount_service_send_required_files(struct mount_service *mo,
+					     const char *fusedev)
+{
+	int ret;
+
+	mo->fusedevfd = open(fusedev, O_RDWR | O_CLOEXEC);
+	if (mo->fusedevfd < 0) {
+		perror(fusedev);
+		return -1;
+	}
+
+	ret = mount_service_send_file(mo, FUSE_SERVICE_ARGV, mo->argvfd);
+	close(mo->argvfd);
+	mo->argvfd = -1;
+	if (ret)
+		return ret;
+
+	return mount_service_send_file(mo, FUSE_SERVICE_FUSEDEV,
+				       mo->fusedevfd);
+}
+
+static int
+mount_service_receive_command(struct mount_service *mo,
+			      struct fuse_service_packet **commandp)
+{
+	struct iovec iov = {
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	struct fuse_service_packet *command;
+	ssize_t size;
+
+	size = recvmsg(mo->sockfd, &msg, MSG_PEEK | MSG_TRUNC);
+	if (size < 0) {
+		perror("mount.service: peek service command");
+		return -1;
+	}
+	if (size == 0) {
+		/* fuse server probably exited early */
+		return -1;
+	}
+	if (size < sizeof(struct fuse_service_packet)) {
+		fprintf(stderr,
+ "mount.service: wrong command packet size %zd, expected at least %zd\n",
+			size, sizeof(struct fuse_service_packet));
+		return -1;
+	}
+
+	command = calloc(1, size + 1);
+	if (!command) {
+		perror("mount.service: alloc service command");
+		return -1;
+	}
+	iov.iov_base = command;
+	iov.iov_len = size;
+
+	size = recvmsg(mo->sockfd, &msg, MSG_TRUNC);
+	if (size < 0) {
+		perror("mount.service: receive service command");
+		return -1;
+	}
+	if (size != iov.iov_len) {
+		fprintf(stderr,
+ "mount.service: wrong service command size %zd, expected %zd\n",
+			size, iov.iov_len);
+		return -1;
+	}
+
+	*commandp = command;
+	return 0;
+}
+
+static int mount_service_send_reply(struct mount_service *mo, int error)
+{
+	struct fuse_service_simple_reply reply = {
+		.p.magic = htonl(FUSE_SERVICE_SIMPLE_REPLY),
+		.error = htonl(error),
+	};
+	struct iovec iov = {
+		.iov_base = &reply,
+		.iov_len = sizeof(reply),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	ssize_t size;
+
+	size = sendmsg(mo->sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+	if (size < 0) {
+		perror("mount.service: send service reply");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int mount_service_handle_open_cmd(struct mount_service *mo,
+					 struct fuse_service_packet *p)
+{
+	struct fuse_service_open_command *oc =
+			container_of(p, struct fuse_service_open_command, p);
+	int ret;
+	int fd;
+
+	fd = open(oc->path, ntohl(oc->flags), ntohl(oc->mode));
+	if (fd >= 0) {
+		ret = mount_service_send_file(mo, oc->path, fd);
+	} else {
+		int error = errno;
+
+		perror(oc->path);
+		ret = mount_service_send_file_error(mo, error, oc->path);
+	}
+	close(fd);
+
+	return ret;
+}
+
+static int
+mount_service_handle_fsopen_cmd(struct mount_service *mo,
+				const struct fuse_service_packet *p)
+{
+	struct fuse_service_string_command *oc =
+			container_of(p, struct fuse_service_string_command, p);
+
+	mo->fsopenfd = -1;
+#if 0
+	mo->fsopenfd = fsopen(oc->value, FSOPEN_CLOEXEC);
+#endif
+	if (mo->fsopenfd >= 0)
+		return mount_service_send_reply(mo, 0);
+
+	if (mo->fstype) {
+		fprintf(stderr, "mount.service: fstype respecified!\n");
+		mount_service_send_reply(mo, EINVAL);
+		return -1;
+	}
+
+	mo->fstype = strdup(oc->value);
+	if (!mo->fstype) {
+		perror("mount.service: alloc fstype string");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	return mount_service_send_reply(mo, 0);
+}
+
+static int
+mount_service_handle_source_cmd(struct mount_service *mo,
+				const struct fuse_service_packet *p)
+{
+	struct fuse_service_string_command *oc =
+			container_of(p, struct fuse_service_string_command, p);
+	int ret;
+
+	if (mo->fsopenfd < 0) {
+		if (mo->source) {
+			fprintf(stderr, "mount.service: source respecified!\n");
+			mount_service_send_reply(mo, EINVAL);
+			return -1;
+		}
+
+		mo->source = strdup(oc->value);
+		if (!mo->source) {
+			perror("mount.service: alloc source string");
+			mount_service_send_reply(mo, errno);
+			return -1;
+		}
+
+		return mount_service_send_reply(mo, 0);
+	}
+
+	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "source", oc->value,
+		       0);
+	if (ret) {
+		perror("mount.service: fsconfig source");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	return mount_service_send_reply(mo, 0);
+}
+
+static int
+mount_service_handle_mntopts_cmd(struct mount_service *mo,
+				 const struct fuse_service_packet *p)
+{
+	struct fuse_service_string_command *oc =
+			container_of(p, struct fuse_service_string_command, p);
+	char *tokstr = oc->value;
+	char *tok, *savetok;
+	int ret;
+
+	if (mo->fsopenfd < 0) {
+		if (mo->mntopts) {
+			fprintf(stderr,
+ "mount.service: mount options respecified!\n");
+			mount_service_send_reply(mo, EINVAL);
+			return -1;
+		}
+
+		mo->mntopts = strdup(oc->value);
+		if (!mo->mntopts) {
+			perror("mount.service: alloc mount options string");
+			mount_service_send_reply(mo, errno);
+			return -1;
+		}
+
+		return mount_service_send_reply(mo, 0);
+	}
+
+	while ((tok = strtok_r(tokstr, ",", &savetok)) != NULL) {
+		char *equals = strchr(tok, '=');
+
+		if (equals) {
+			char oldchar = *equals;
+
+			*equals = 0;
+			ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, tok,
+				       equals + 1, 0);
+			*equals = oldchar;
+		} else {
+			ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_FLAG, tok,
+				       NULL, 0);
+		}
+		if (ret) {
+			perror("mount.service: set mount option");
+			mount_service_send_reply(mo, errno);
+			return -1;
+		}
+
+		tokstr = NULL;
+	}
+
+	return mount_service_send_reply(mo, 0);
+}
+
+static int
+mount_service_handle_mountpoint_cmd(struct mount_service *mo,
+				    const struct fuse_service_packet *p)
+{
+	struct fuse_service_string_command *oc =
+			container_of(p, struct fuse_service_string_command, p);
+
+	if (mo->mountpoint) {
+		fprintf(stderr, "mount.service: mount point respecified!\n");
+		mount_service_send_reply(mo, EINVAL);
+		return -1;
+	}
+
+	mo->mountpoint = strdup(oc->value);
+	if (!mo->mountpoint) {
+		perror("mount.service: alloc mount point string");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	return mount_service_send_reply(mo, 0);
+}
+
+static inline int format_libfuse_mntopts(char *buf, size_t bufsz,
+					 const struct mount_service *mo,
+					 const struct stat *statbuf)
+{
+	if (mo->mntopts)
+		return snprintf(buf, bufsz,
+				"%s,fd=%i,rootmode=%o,user_id=%u,group_id=%u",
+				mo->mntopts, mo->fusedevfd,
+				statbuf->st_mode & S_IFMT,
+				getuid(), getgid());
+
+	return snprintf(buf, bufsz,
+			"fd=%i,rootmode=%o,user_id=%u,group_id=%u",
+			mo->fusedevfd, statbuf->st_mode & S_IFMT,
+			getuid(), getgid());
+}
+
+static int mount_service_regular_mount(struct mount_service *mo,
+				       struct fuse_service_mount_command *oc,
+				       struct stat *stbuf)
+{
+	char *realmopts;
+	int ret;
+
+	if (!mo->fstype) {
+		fprintf(stderr, "mount.service: missing mount type parameter\n");
+		mount_service_send_reply(mo, EINVAL);
+		return -1;
+	}
+
+	if (!mo->source) {
+		fprintf(stderr, "mount.service: missing mount source parameter\n");
+		mount_service_send_reply(mo, EINVAL);
+		return -1;
+	}
+
+	ret = format_libfuse_mntopts(NULL, 0, mo, stbuf);
+	if (ret < 0) {
+		perror("mount.service: mount option preformatting");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	realmopts = malloc(ret + 1);
+	if (!realmopts) {
+		perror("mount.service: alloc real mount options string");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	ret = format_libfuse_mntopts(realmopts, ret + 1, mo, stbuf);
+	if (ret < 0) {
+		free(realmopts);
+		perror("mount.service: mount options formatting");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	ret = mount(mo->source, mo->mountpoint, mo->fstype, ntohl(oc->flags),
+		    realmopts);
+	free(realmopts);
+	if (ret) {
+		perror("mount.service");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	return mount_service_send_reply(mo, 0);
+}
+
+static int mount_service_fsopen_mount(struct mount_service *mo,
+				      struct fuse_service_mount_command *oc,
+				      struct stat *stbuf)
+{
+	char tmp[64];
+	int mfd;
+	int ret;
+
+	snprintf(tmp, sizeof(tmp), "%i", mo->fusedevfd);
+	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "fd", tmp, 0);
+	if (ret) {
+		perror("mount.service: set fd option");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	snprintf(tmp, sizeof(tmp), "%o", stbuf->st_mode & S_IFMT);
+	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "rootmode", tmp, 0);
+	if (ret) {
+		perror("mount.service: set rootmode option");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	snprintf(tmp, sizeof(tmp), "%u", getuid());
+	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "user_id", tmp, 0);
+	if (ret) {
+		perror("mount.service: set user_id option");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	snprintf(tmp, sizeof(tmp), "%u", getgid());
+	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "group_id", tmp, 0);
+	if (ret) {
+		perror("mount.service: set group_id option");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	mfd = fsmount(mo->fsopenfd, FSMOUNT_CLOEXEC, ntohl(oc->flags));
+	if (mfd < 0) {
+		perror("mount.service");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	ret = move_mount(mfd, "", AT_FDCWD, mo->mountpoint,
+			 MOVE_MOUNT_F_EMPTY_PATH);
+	close(mfd);
+	if (ret) {
+		perror("mount.service: move_mount");
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	return mount_service_send_reply(mo, 0);
+}
+
+static int mount_service_handle_mount_cmd(struct mount_service *mo,
+					  struct fuse_service_packet *p)
+{
+	struct stat stbuf;
+	char mountpoint[PATH_MAX] = "";
+	struct fuse_service_mount_command *oc =
+			container_of(p, struct fuse_service_mount_command, p);
+	int ret;
+
+	if (!mo->mountpoint) {
+		fprintf(stderr, "mount.service: missing mount point parameter\n");
+		mount_service_send_reply(mo, EINVAL);
+		return -1;
+	}
+
+	if (realpath(mo->mountpoint, mountpoint) == NULL) {
+		int error = errno;
+
+		fprintf(stderr, "mount.service: bad mount point `%s': %s\n",
+			mo->mountpoint, strerror(error));
+		mount_service_send_reply(mo, error);
+		return -1;
+	}
+
+	ret = stat(mo->mountpoint, &stbuf);
+	if (ret == -1) {
+		perror(mo->mountpoint);
+		mount_service_send_reply(mo, errno);
+		return -1;
+	}
+
+	if (mo->fsopenfd >= 0)
+		return mount_service_fsopen_mount(mo, oc, &stbuf);
+	return mount_service_regular_mount(mo, oc, &stbuf);
+}
+
+static int mount_service_handle_bye_cmd(struct fuse_service_packet *p)
+{
+	int error;
+
+	struct fuse_service_bye_command *bc =
+			container_of(p, struct fuse_service_bye_command, p);
+
+	error = ntohl(bc->error);
+	if (error) {
+		fprintf(stderr, "mount.service: initialization failed: %s\n",
+			strerror(error));
+		return -1;
+	}
+
+	return 0;
+}
+
+static void mount_service_destroy(struct mount_service *mo)
+{
+	close(mo->fusedevfd);
+	close(mo->argvfd);
+	close(mo->fsopenfd);
+	shutdown(mo->sockfd, SHUT_RDWR);
+	close(mo->sockfd);
+
+	free(mo->source);
+	free(mo->mountpoint);
+	free(mo->mntopts);
+	free(mo->fstype);
+
+	memset(mo, 0, sizeof(*mo));
+	mo->fsopenfd = -1;
+	mo->sockfd = -1;
+	mo->argvfd = -1;
+	mo->fusedevfd = -1;
+}
+
+int mount_service_main(int argc, char *argv[])
+{
+	const char *fusedev = getenv(FUSE_KERN_DEVICE_ENV) ?: FUSE_DEV;
+	struct mount_service mo = { };
+	bool running = true;
+	int ret;
+
+	if (argc < 3 || !strcmp(argv[1], "--help")) {
+		printf("Usage: %s source mountpoint -t type [-o options]\n",
+				argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	ret = mount_service_init(&mo, argc, argv);
+	if (ret) {
+		fprintf(stderr, "%s: cannot determine filesystem type.\n",
+			argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	ret = mount_service_connect(&mo);
+	if (ret) {
+		ret = EXIT_FAILURE;
+		goto out;
+	}
+
+	ret = mount_service_send_hello(&mo);
+	if (ret) {
+		ret = EXIT_FAILURE;
+		goto out;
+	}
+
+	ret = mount_service_capture_args(&mo, argc, argv);
+	if (ret) {
+		ret = EXIT_FAILURE;
+		goto out;
+	}
+
+	ret = mount_service_send_required_files(&mo, fusedev);
+	if (ret) {
+		ret = EXIT_FAILURE;
+		goto out;
+	}
+
+	while (running) {
+		struct fuse_service_packet *p = NULL;
+
+		ret = mount_service_receive_command(&mo, &p);
+		if (ret) {
+			ret = EXIT_FAILURE;
+			goto out;
+		}
+
+		switch (ntohl(p->magic)) {
+		case FUSE_SERVICE_OPEN_CMD:
+			ret = mount_service_handle_open_cmd(&mo, p);
+			break;
+		case FUSE_SERVICE_FSOPEN_CMD:
+			ret = mount_service_handle_fsopen_cmd(&mo, p);
+			break;
+		case FUSE_SERVICE_SOURCE_CMD:
+			ret = mount_service_handle_source_cmd(&mo, p);
+			break;
+		case FUSE_SERVICE_MNTOPTS_CMD:
+			ret = mount_service_handle_mntopts_cmd(&mo, p);
+			break;
+		case FUSE_SERVICE_MNTPT_CMD:
+			ret = mount_service_handle_mountpoint_cmd(&mo, p);
+			break;
+		case FUSE_SERVICE_MOUNT_CMD:
+			ret = mount_service_handle_mount_cmd(&mo, p);
+			break;
+		case FUSE_SERVICE_BYE_CMD:
+			ret = mount_service_handle_bye_cmd(p);
+			running = false;
+			break;
+		default:
+			fprintf(stderr, "unrecognized packet 0x%x\n",
+				ntohl(p->magic));
+			ret = EXIT_FAILURE;
+			break;
+		}
+		free(p);
+
+		if (ret) {
+			ret = EXIT_FAILURE;
+			goto out;
+		}
+	}
+
+	ret = EXIT_SUCCESS;
+out:
+	mount_service_destroy(&mo);
+	return ret;
+}

[PATCH 2/4] libfuse: integrate fuse services into mount.fuse3

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Teach mount.fuse3 how to start fuse via service, if present.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 util/mount_service.h  |    9 ++++++++
 doc/fuservicemount3.8 |   10 ++++++++
 util/fuservicemount.c |   48 +++++++++++++++++++++++++++++++++++++++++
 util/meson.build      |    4 +++
 util/mount.fuse.c     |   58 +++++++++++++++++++++++++++++++------------------
 util/mount_service.c  |   18 +++++++++++++++
 6 files changed, 124 insertions(+), 23 deletions(-)


diff --git a/util/mount_service.h b/util/mount_service.h
index 986a785bed3e74..b3e449ef005231 100644
--- a/util/mount_service.h
+++ b/util/mount_service.h
@@ -29,4 +29,13 @@ int mount_service_main(int argc, char *argv[]);
  */
 const char *mount_service_subtype(const char *fstype);
 
+/**
+ * Discover if there is a fuse service socket for the given fuse subtype.
+ *
+ * @param subtype subtype of a fuse filesystem type (e.g. Y from
+ *                mount_service_subtype)
+ * @return true if available, false if not
+ */
+bool mount_service_present(const char *subtype);
+
 #endif /* MOUNT_SERVICE_H_ */
diff --git a/doc/fuservicemount3.8 b/doc/fuservicemount3.8
index e45d6a89c8b81a..aa2167cb4872c6 100644
--- a/doc/fuservicemount3.8
+++ b/doc/fuservicemount3.8
@@ -7,12 +7,20 @@ .SH SYNOPSIS
 .B mountpoint
 .BI -t " fstype"
 [
-.I options
+.BI -o " options"
 ]
+
+.B fuservicemount3
+.BI -t " fstype"
+.B --check
+
 .SH DESCRIPTION
 Mount a filesystem using a FUSE server that runs as a socket service.
 These servers can be contained using the platform's service management
 framework.
+
+The second form checks if there is a FUSE service available for the given
+filesystem type.
 .SH "AUTHORS"
 .LP
 The author of the fuse socket service code is Darrick J. Wong <djwong@kernel.org>.
diff --git a/util/fuservicemount.c b/util/fuservicemount.c
index c54d5b0767f760..edff2ed08ac23b 100644
--- a/util/fuservicemount.c
+++ b/util/fuservicemount.c
@@ -9,10 +9,58 @@
 /* This program does the mounting of FUSE filesystems that run in systemd */
 
 #define _GNU_SOURCE
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
 #include "fuse_config.h"
 #include "mount_service.h"
 
+static int check_service(const char *fstype)
+{
+	const char *subtype;
+
+	if (!fstype) {
+		fprintf(stderr,
+			"fuservicemount: expected fs type for --check\n");
+		return EXIT_FAILURE;
+	}
+
+	subtype = mount_service_subtype(fstype);
+	return mount_service_present(subtype) ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+
 int main(int argc, char *argv[])
 {
+	char *fstype = NULL;
+	bool check = false;
+	int i;
+
+	/*
+	 * If the user passes us exactly the args -t FSTYPE --check then
+	 * we'll just check if there's a service for the FSTYPE fuse server.
+	 */
+	for (i = 1; i < argc; i++) {
+		if (!strcmp(argv[i], "--check")) {
+			if (check) {
+				check = false;
+				break;
+			}
+			check = true;
+		} else if (!strcmp(argv[i], "-t") && i + 1 < argc) {
+			if (fstype) {
+				check = false;
+				break;
+			}
+			fstype = argv[i + 1];
+			i++;
+		} else {
+			check = false;
+			break;
+		}
+	}
+	if (check)
+		return check_service(fstype);
+
 	return mount_service_main(argc, argv);
 }
diff --git a/util/meson.build b/util/meson.build
index 68d8bb11f92955..3adf395bfb6386 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -6,7 +6,9 @@ executable('fusermount3', ['fusermount.c', '../lib/mount_util.c', '../lib/util.c
            install_dir: get_option('bindir'),
            c_args: '-DFUSE_CONF="@0@"'.format(fuseconf_path))
 
+mount_fuse3_sources = ['mount.fuse.c']
 if private_cfg.get('HAVE_SERVICEMOUNT', false)
+  mount_fuse3_sources += ['mount_service.c']
   executable('fuservicemount3', ['mount_service.c', 'fuservicemount.c'],
              include_directories: include_dirs,
              link_with: [ libfuse ],
@@ -15,7 +17,7 @@ if private_cfg.get('HAVE_SERVICEMOUNT', false)
              c_args: '-DFUSE_USE_VERSION=317')
 endif
 
-executable('mount.fuse3', ['mount.fuse.c'],
+executable('mount.fuse3', mount_fuse3_sources,
            include_directories: include_dirs,
            link_with: [ libfuse ],
            install: true,
diff --git a/util/mount.fuse.c b/util/mount.fuse.c
index f1a90fe8abae7c..b6a55eebb7f88b 100644
--- a/util/mount.fuse.c
+++ b/util/mount.fuse.c
@@ -49,6 +49,9 @@
 #endif
 
 #include "fuse.h"
+#ifdef HAVE_SERVICEMOUNT
+# include "mount_service.h"
+#endif
 
 static char *progname;
 
@@ -280,9 +283,7 @@ int main(int argc, char *argv[])
 	mountpoint = argv[2];
 
 	for (i = 3; i < argc; i++) {
-		if (strcmp(argv[i], "-v") == 0) {
-			continue;
-		} else if (strcmp(argv[i], "-t") == 0) {
+		if (strcmp(argv[i], "-t") == 0) {
 			i++;
 
 			if (i == argc) {
@@ -303,6 +304,39 @@ int main(int argc, char *argv[])
 					progname);
 				exit(1);
 			}
+		}
+	}
+
+	if (!type) {
+		if (source) {
+			dup_source = xstrdup(source);
+			type = dup_source;
+			source = strchr(type, '#');
+			if (source)
+				*source++ = '\0';
+			if (!type[0]) {
+				fprintf(stderr, "%s: empty filesystem type\n",
+					progname);
+				exit(1);
+			}
+		} else {
+			fprintf(stderr, "%s: empty source\n", progname);
+			exit(1);
+		}
+	}
+
+#ifdef HAVE_SERVICEMOUNT
+	/*
+	 * Now that we know the desired filesystem type, see if we can find
+	 * a socket service implementing that.
+	 */
+	if (mount_service_present(type))
+		return mount_service_main(argc, argv);
+#endif
+
+	for (i = 3; i < argc; i++) {
+		if (strcmp(argv[i], "-v") == 0) {
+			continue;
 		} else	if (strcmp(argv[i], "-o") == 0) {
 			char *opts;
 			char *opt;
@@ -366,24 +400,6 @@ int main(int argc, char *argv[])
 	if (suid)
 		options = add_option("suid", options);
 
-	if (!type) {
-		if (source) {
-			dup_source = xstrdup(source);
-			type = dup_source;
-			source = strchr(type, '#');
-			if (source)
-				*source++ = '\0';
-			if (!type[0]) {
-				fprintf(stderr, "%s: empty filesystem type\n",
-					progname);
-				exit(1);
-			}
-		} else {
-			fprintf(stderr, "%s: empty source\n", progname);
-			exit(1);
-		}
-	}
-
 	if (setuid_name && setuid_name[0]) {
 #ifdef linux
 		if (drop_privileges) {
diff --git a/util/mount_service.c b/util/mount_service.c
index 46d368d0cba922..612fec327cedde 100644
--- a/util/mount_service.c
+++ b/util/mount_service.c
@@ -960,3 +960,21 @@ int mount_service_main(int argc, char *argv[])
 	mount_service_destroy(&mo);
 	return ret;
 }
+
+bool mount_service_present(const char *fstype)
+{
+	struct stat stbuf;
+	char path[PATH_MAX];
+	int ret;
+
+	snprintf(path, sizeof(path), FUSE_SERVICE_SOCKET_DIR "/%s", fstype);
+	ret = stat(path, &stbuf);
+	if (ret)
+		return false;
+
+	if (!S_ISSOCK(stbuf.st_mode))
+		return false;
+
+	ret = access(path, R_OK | W_OK);
+	return ret == 0;
+}

[PATCH 3/4] libfuse: delegate iomap privilege from mount.service to fuse services

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Enable the mount.service helper to attach whatever privileges it might
have to enable iomap to a /dev/fuse fd before passing that fd to the
fuse server.  Assuming that the fuse service itself does not have
sufficient privilege to enable iomap on its own, it can now inherit that
privilege via the fd.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_kernel.h       |    1 +
 include/fuse_lowlevel.h     |   11 +++++++
 include/fuse_service.h      |   11 +++++++
 include/fuse_service_priv.h |   10 +++++++
 lib/fuse_lowlevel.c         |    5 +++
 lib/fuse_service.c          |   49 +++++++++++++++++++++++++++++++++
 lib/fuse_versionscript      |    2 +
 util/mount_service.c        |   64 +++++++++++++++++++++++++++++++++++++++++++
 8 files changed, 152 insertions(+), 1 deletion(-)


diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 3bb26fce2f6a0e..3b88b36c04ae02 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -1169,6 +1169,7 @@ struct fuse_iomap_support {
 #define FUSE_DEV_IOC_BACKING_OPEN	_IOW(FUSE_DEV_IOC_MAGIC, 1, \
 					     struct fuse_backing_map)
 #define FUSE_DEV_IOC_BACKING_CLOSE	_IOW(FUSE_DEV_IOC_MAGIC, 2, uint32_t)
+#define FUSE_DEV_IOC_ADD_IOMAP		_IO(FUSE_DEV_IOC_MAGIC, 99)
 #define FUSE_DEV_IOC_IOMAP_SUPPORT	_IOR(FUSE_DEV_IOC_MAGIC, 99, \
 					     struct fuse_iomap_support)
 
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 1d73f2befc5f3c..7a99f05e2de841 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -2673,7 +2673,6 @@ bool fuse_req_is_uring(fuse_req_t req);
 int fuse_req_get_payload(fuse_req_t req, char **payload, size_t *payload_sz,
 			 void **mr);
 
-
 /**
  * Discover the kernel's iomap capabilities.  Returns FUSE_CAP_IOMAP_* flags.
  *
@@ -2683,6 +2682,16 @@ int fuse_req_get_payload(fuse_req_t req, char **payload, size_t *payload_sz,
  */
 uint64_t fuse_lowlevel_discover_iomap(int fd);
 
+/**
+ * Request that iomap capabilities be added to this fuse device.  This enables
+ * a privileged mount helper to convey the privileges that allow iomap usage to
+ * a completely unprivileged fuse server.
+ *
+ * @param fd open file descriptor to a fuse device
+ * @return 0 on success, -1 on failure with errno set
+ */
+int fuse_lowlevel_add_iomap(int fd);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/fuse_service.h b/include/fuse_service.h
index 7c44c701bd695b..4e0923bafb0703 100644
--- a/include/fuse_service.h
+++ b/include/fuse_service.h
@@ -126,6 +126,17 @@ int fuse_service_receive_file(struct fuse_service *sf,
  */
 int fuse_service_finish_file_requests(struct fuse_service *sf);
 
+/**
+ * Attach iomap to the fuse connection.
+ *
+ * @param sf service context
+ * @param mandatory true if the server requires iomap
+ * @param error result of trying to enable iomap
+ * @return 0 on success, -1 on error
+ */
+int fuse_service_configure_iomap(struct fuse_service *sf, bool mandatory,
+				 int *error);
+
 /**
  * Ask the mount.service helper to mount the filesystem for us.  The fuse client
  * will begin sending requests to the fuse server immediately after this.
diff --git a/include/fuse_service_priv.h b/include/fuse_service_priv.h
index 1c01a7ba9614f2..c57fd4c563bac3 100644
--- a/include/fuse_service_priv.h
+++ b/include/fuse_service_priv.h
@@ -32,6 +32,7 @@ struct fuse_service_memfd_argv {
 #define FUSE_SERVICE_MNTPT_CMD		0x4d4e5450	/* MNTP */
 #define FUSE_SERVICE_MOUNT_CMD		0x444f4954	/* DOIT */
 #define FUSE_SERVICE_BYE_CMD		0x42594545	/* BYEE */
+#define FUSE_SERVICE_IOMAP_CMD		0x494f4d41	/* IOMA */
 
 /* mount.service sends replies to the fuse server */
 #define FUSE_SERVICE_OPEN_REPLY		0x46494c45	/* FILE */
@@ -69,6 +70,15 @@ static inline size_t sizeof_fuse_service_open_command(size_t pathlen)
 	return sizeof(struct fuse_service_open_command) + pathlen + 1;
 }
 
+#define FUSE_IOMAP_MODE_OPTIONAL	0x503F /* P? */
+#define FUSE_IOMAP_MODE_MANDATORY	0x5021 /* P! */
+
+struct fuse_service_iomap_command {
+	struct fuse_service_packet p;
+	__be16 mode;
+	__be16 padding;
+};
+
 struct fuse_service_string_command {
 	struct fuse_service_packet p;
 	char value[];
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 460ade5a9704a4..784c90d8cd1e3f 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -4839,3 +4839,8 @@ uint64_t fuse_lowlevel_discover_iomap(int fd)
 
 	return ios.flags;
 }
+
+int fuse_lowlevel_add_iomap(int fd)
+{
+	return ioctl(fd, FUSE_DEV_IOC_ADD_IOMAP);
+}
diff --git a/lib/fuse_service.c b/lib/fuse_service.c
index ab50f0017b255c..d378cb01f72665 100644
--- a/lib/fuse_service.c
+++ b/lib/fuse_service.c
@@ -617,6 +617,55 @@ static int send_mount(struct fuse_service *sf, unsigned int flags, int *error)
 	return 0;
 }
 
+int fuse_service_configure_iomap(struct fuse_service *sf, bool mandatory,
+				 int *error)
+{
+	struct fuse_service_iomap_command cmd = {
+		.p.magic = ntohl(FUSE_SERVICE_IOMAP_CMD),
+		.mode = mandatory ? ntohs(FUSE_IOMAP_MODE_MANDATORY) :
+				    ntohs(FUSE_IOMAP_MODE_OPTIONAL),
+	};
+	struct fuse_service_simple_reply reply = { };
+	struct iovec iov = {
+		.iov_base = &cmd,
+		.iov_len = sizeof(cmd),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	ssize_t size;
+
+	size = sendmsg(sf->sockfd, &msg, MSG_EOR | MSG_NOSIGNAL);
+	if (size < 0) {
+		perror("fuse: send iomap command");
+		return -1;
+	}
+
+	iov.iov_base = &reply;
+	iov.iov_len = sizeof(reply);
+	size = recvmsg(sf->sockfd, &msg, MSG_TRUNC);
+	if (size < 0) {
+		perror("fuse: iomap command reply");
+		return -1;
+	}
+	if (size != sizeof(reply)) {
+		fprintf(stderr,
+ "fuse: wrong iomap command reply size %zd, expected %zd\n",
+			size, sizeof(reply));
+		return -1;
+	}
+
+	if (ntohl(reply.p.magic) != FUSE_SERVICE_SIMPLE_REPLY) {
+		fprintf(stderr,
+ "fuse: iomap command reply contains wrong magic!\n");
+		return -1;
+	}
+
+	*error = ntohl(reply.error);
+	return 0;
+}
+
 int fuse_service_mount(struct fuse_service *sf, struct fuse_session *se,
 		       const char *mountpoint)
 {
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 335e18063bab00..39bc1e1036007a 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -240,9 +240,11 @@ FUSE_3.99 {
 		fuse_lowlevel_notify_iomap_inval;
 		fuse_fs_iomap_upsert;
 		fuse_fs_iomap_inval;
+		fuse_lowlevel_add_iomap;
 
 		fuse_service_accept;
 		fuse_service_append_args;
+		fuse_service_configure_iomap;
 		fuse_service_destroy;
 		fuse_service_finish_file_requests;
 		fuse_service_mount;
diff --git a/util/mount_service.c b/util/mount_service.c
index 612fec327cedde..ceaa74f8a6127e 100644
--- a/util/mount_service.c
+++ b/util/mount_service.c
@@ -62,6 +62,9 @@ struct mount_service {
 
 	/* fd for fsopen */
 	int fsopenfd;
+
+	/* did someone configure iomap already? */
+	int iomap_configured:1;
 };
 
 /* Filter out the subtype of the filesystem (e.g. fuse.Y -> Y) */
@@ -399,6 +402,22 @@ static int mount_service_send_file_error(struct mount_service *mo, int error,
 	return ret;
 }
 
+static int mount_service_config_iomap(struct mount_service *mo,
+				      bool mandatory)
+{
+	int ret;
+
+	mo->iomap_configured = 1;
+
+	ret = fuse_lowlevel_add_iomap(mo->fusedevfd);
+	if (ret && mandatory) {
+		perror("mount.service: adding iomap capability");
+		return -errno;
+	}
+
+	return 0;
+}
+
 static int mount_service_send_required_files(struct mount_service *mo,
 					     const char *fusedev)
 {
@@ -721,6 +740,13 @@ static int mount_service_regular_mount(struct mount_service *mo,
 		return -1;
 	}
 
+	/*
+	 * If nobody tried to configure iomap, try to enable it but don't
+	 * fail if we can't.
+	 */
+	if (!mo->iomap_configured)
+		mount_service_config_iomap(mo, false);
+
 	ret = mount(mo->source, mo->mountpoint, mo->fstype, ntohl(oc->flags),
 		    realmopts);
 	free(realmopts);
@@ -792,6 +818,41 @@ static int mount_service_fsopen_mount(struct mount_service *mo,
 	return mount_service_send_reply(mo, 0);
 }
 
+static int mount_service_handle_iomap_cmd(struct mount_service *mo,
+					  struct fuse_service_packet *p)
+{
+	struct fuse_service_iomap_command *oc =
+			container_of(p, struct fuse_service_iomap_command, p);
+	bool mandatory = false;
+	int ret;
+
+	if (oc->padding) {
+		fprintf(stderr, "mount.service: invalid iomap command\n");
+		mount_service_send_reply(mo, EINVAL);
+		return -1;
+	}
+
+	switch (ntohs(oc->mode)) {
+	case FUSE_IOMAP_MODE_MANDATORY:
+		mandatory = true;
+		/* fallthrough */
+	case FUSE_IOMAP_MODE_OPTIONAL:
+		ret = mount_service_config_iomap(mo, mandatory);
+		break;
+	default:
+		fprintf(stderr, "mount.service: invalid iomap command mode\n");
+		ret = -1;
+	}
+
+	if (ret < 0) {
+		mount_service_send_reply(mo, -ret);
+		return -1;
+	}
+
+	mount_service_send_reply(mo, 0);
+	return 0;
+}
+
 static int mount_service_handle_mount_cmd(struct mount_service *mo,
 					  struct fuse_service_packet *p)
 {
@@ -934,6 +995,9 @@ int mount_service_main(int argc, char *argv[])
 		case FUSE_SERVICE_MNTPT_CMD:
 			ret = mount_service_handle_mountpoint_cmd(&mo, p);
 			break;
+		case FUSE_SERVICE_IOMAP_CMD:
+			ret = mount_service_handle_iomap_cmd(&mo, p);
+			break;
 		case FUSE_SERVICE_MOUNT_CMD:
 			ret = mount_service_handle_mount_cmd(&mo, p);
 			break;

[PATCH 4/4] libfuse: enable setting iomap block device block size

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create a means for an unprivileged fuse server to set the block size of
a block device that it previously opened and associated with the fuse
connection.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_kernel.h   |    7 +++++++
 include/fuse_lowlevel.h |   12 ++++++++++++
 lib/fuse_lowlevel.c     |   11 +++++++++++
 lib/fuse_versionscript  |    1 +
 4 files changed, 31 insertions(+)


diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 3b88b36c04ae02..01a1372afb40b3 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -1163,6 +1163,11 @@ struct fuse_iomap_support {
 	uint64_t	padding;
 };
 
+struct fuse_iomap_backing_info {
+	uint32_t	backing_id;
+	uint32_t	blocksize;
+};
+
 /* Device ioctls: */
 #define FUSE_DEV_IOC_MAGIC		229
 #define FUSE_DEV_IOC_CLONE		_IOR(FUSE_DEV_IOC_MAGIC, 0, uint32_t)
@@ -1172,6 +1177,8 @@ struct fuse_iomap_support {
 #define FUSE_DEV_IOC_ADD_IOMAP		_IO(FUSE_DEV_IOC_MAGIC, 99)
 #define FUSE_DEV_IOC_IOMAP_SUPPORT	_IOR(FUSE_DEV_IOC_MAGIC, 99, \
 					     struct fuse_iomap_support)
+#define FUSE_DEV_IOC_IOMAP_SET_BLOCKSIZE _IOW(FUSE_DEV_IOC_MAGIC, 99, \
+					      struct fuse_iomap_backing_info)
 
 struct fuse_lseek_in {
 	uint64_t	fh;
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 7a99f05e2de841..43098cb655effa 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -2692,6 +2692,18 @@ uint64_t fuse_lowlevel_discover_iomap(int fd);
  */
 int fuse_lowlevel_add_iomap(int fd);
 
+/**
+ * Set the block size of an open block device that has been opened for use with
+ * iomap.
+ *
+ * @param fd open file descriptor to a fuse device
+ * @param dev_index device index returned by fuse_lowlevel_iomap_device_add
+ * @param blocksize block size in bytes
+ * @return 0 on success, -1 on failure with errno set
+ */
+int fuse_lowlevel_iomap_set_blocksize(int fd, int dev_index,
+				      unsigned int blocksize);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 784c90d8cd1e3f..68e979e2ab334e 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -4844,3 +4844,14 @@ int fuse_lowlevel_add_iomap(int fd)
 {
 	return ioctl(fd, FUSE_DEV_IOC_ADD_IOMAP);
 }
+
+int fuse_lowlevel_iomap_set_blocksize(int fd, int dev_index,
+				      unsigned int blocksize)
+{
+	struct fuse_iomap_backing_info fbi = {
+		.backing_id = dev_index,
+		.blocksize = blocksize,
+	};
+
+	return ioctl(fd, FUSE_DEV_IOC_IOMAP_SET_BLOCKSIZE, &fbi);
+}
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 39bc1e1036007a..c45be2a92e59b9 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -255,6 +255,7 @@ FUSE_3.99 {
 		fuse_service_request_file;
 		fuse_service_send_goodbye;
 		fuse_service_take_fusedev;
+		fuse_lowlevel_iomap_set_blocksize;
 } FUSE_3.18;
 
 # Local Variables:

[PATCH 01/21] fuse2fs: separate libfuse3 and fuse2fs detection in configure

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Separate the detection of libfuse and fuse2fs so that we can add another
fuse server (fuse4fs) without tangling it up in --disable-fuse2fs.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 configure        |  301 +++++++++++++-----------------------------------------
 configure.ac     |   79 ++++++++------
 misc/Makefile.in |    6 +
 3 files changed, 116 insertions(+), 270 deletions(-)


diff --git a/configure b/configure
index 86c9bc77321eee..22031343f078ab 100755
--- a/configure
+++ b/configure
@@ -701,7 +701,7 @@ gcc_ranlib
 gcc_ar
 UNI_DIFF_OPTS
 SEM_INIT_LIB
-FUSE_CMT
+FUSE2FS_CMT
 FUSE_LIB
 fuse3_LIBS
 fuse3_CFLAGS
@@ -14052,214 +14052,8 @@ then :
 fi
 
 
-FUSE_CMT=
+
 FUSE_LIB=
-# Check whether --enable-fuse2fs was given.
-if test ${enable_fuse2fs+y}
-then :
-  enableval=$enable_fuse2fs;
-	if test "$enableval" = "no"
-	then
-		FUSE_CMT="#"
-		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Disabling fuse2fs" >&5
-printf "%s\n" "Disabling fuse2fs" >&6; }
-	else
-		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#ifdef __linux__
-	#include <linux/fs.h>
-	#include <linux/falloc.h>
-	#include <linux/xattr.h>
-	#endif
-
-int
-main (void)
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_cpp "$LINENO"
-then :
-
-else $as_nop
-  { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "Cannot find fuse2fs Linux headers.
-See \`config.log' for more details" "$LINENO" 5; }
-fi
-rm -f conftest.err conftest.i conftest.$ac_ext
-
-
-pkg_failed=no
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse3" >&5
-printf %s "checking for fuse3... " >&6; }
-
-if test -n "$fuse3_CFLAGS"; then
-    pkg_cv_fuse3_CFLAGS="$fuse3_CFLAGS"
- elif test -n "$PKG_CONFIG"; then
-    if test -n "$PKG_CONFIG" && \
-    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"fuse3\""; } >&5
-  ($PKG_CONFIG --exists --print-errors "fuse3") 2>&5
-  ac_status=$?
-  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
-  test $ac_status = 0; }; then
-  pkg_cv_fuse3_CFLAGS=`$PKG_CONFIG --cflags "fuse3" 2>/dev/null`
-		      test "x$?" != "x0" && pkg_failed=yes
-else
-  pkg_failed=yes
-fi
- else
-    pkg_failed=untried
-fi
-if test -n "$fuse3_LIBS"; then
-    pkg_cv_fuse3_LIBS="$fuse3_LIBS"
- elif test -n "$PKG_CONFIG"; then
-    if test -n "$PKG_CONFIG" && \
-    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"fuse3\""; } >&5
-  ($PKG_CONFIG --exists --print-errors "fuse3") 2>&5
-  ac_status=$?
-  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
-  test $ac_status = 0; }; then
-  pkg_cv_fuse3_LIBS=`$PKG_CONFIG --libs "fuse3" 2>/dev/null`
-		      test "x$?" != "x0" && pkg_failed=yes
-else
-  pkg_failed=yes
-fi
- else
-    pkg_failed=untried
-fi
-
-
-
-if test $pkg_failed = yes; then
-        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-
-if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
-        _pkg_short_errors_supported=yes
-else
-        _pkg_short_errors_supported=no
-fi
-        if test $_pkg_short_errors_supported = yes; then
-                fuse3_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "fuse3" 2>&1`
-        else
-                fuse3_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "fuse3" 2>&1`
-        fi
-        # Put the nasty error message in config.log where it belongs
-        echo "$fuse3_PKG_ERRORS" >&5
-
-
-			{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse_main in -losxfuse" >&5
-printf %s "checking for fuse_main in -losxfuse... " >&6; }
-if test ${ac_cv_lib_osxfuse_fuse_main+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  ac_check_lib_save_LIBS=$LIBS
-LIBS="-losxfuse  $LIBS"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-char fuse_main ();
-int
-main (void)
-{
-return fuse_main ();
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"
-then :
-  ac_cv_lib_osxfuse_fuse_main=yes
-else $as_nop
-  ac_cv_lib_osxfuse_fuse_main=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_osxfuse_fuse_main" >&5
-printf "%s\n" "$ac_cv_lib_osxfuse_fuse_main" >&6; }
-if test "x$ac_cv_lib_osxfuse_fuse_main" = xyes
-then :
-  FUSE_LIB=-losxfuse
-else $as_nop
-  { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "Cannot find fuse library.
-See \`config.log' for more details" "$LINENO" 5; }
-fi
-
-
-elif test $pkg_failed = untried; then
-        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-
-			{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse_main in -losxfuse" >&5
-printf %s "checking for fuse_main in -losxfuse... " >&6; }
-if test ${ac_cv_lib_osxfuse_fuse_main+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  ac_check_lib_save_LIBS=$LIBS
-LIBS="-losxfuse  $LIBS"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-char fuse_main ();
-int
-main (void)
-{
-return fuse_main ();
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"
-then :
-  ac_cv_lib_osxfuse_fuse_main=yes
-else $as_nop
-  ac_cv_lib_osxfuse_fuse_main=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_osxfuse_fuse_main" >&5
-printf "%s\n" "$ac_cv_lib_osxfuse_fuse_main" >&6; }
-if test "x$ac_cv_lib_osxfuse_fuse_main" = xyes
-then :
-  FUSE_LIB=-losxfuse
-else $as_nop
-  { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "Cannot find fuse library.
-See \`config.log' for more details" "$LINENO" 5; }
-fi
-
-
-else
-        fuse3_CFLAGS=$pkg_cv_fuse3_CFLAGS
-        fuse3_LIBS=$pkg_cv_fuse3_LIBS
-        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-printf "%s\n" "yes" >&6; }
-        FUSE_LIB=-lfuse3
-fi
-		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Enabling fuse2fs" >&5
-printf "%s\n" "Enabling fuse2fs" >&6; }
-	fi
-
-else $as_nop
-
 
 pkg_failed=no
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse3" >&5
@@ -14320,7 +14114,7 @@ fi
         echo "$fuse3_PKG_ERRORS" >&5
 
 
-		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse_main in -losxfuse" >&5
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse_main in -losxfuse" >&5
 printf %s "checking for fuse_main in -losxfuse... " >&6; }
 if test ${ac_cv_lib_osxfuse_fuse_main+y}
 then :
@@ -14358,8 +14152,6 @@ printf "%s\n" "$ac_cv_lib_osxfuse_fuse_main" >&6; }
 if test "x$ac_cv_lib_osxfuse_fuse_main" = xyes
 then :
   FUSE_LIB=-losxfuse
-else $as_nop
-  FUSE_CMT="#"
 fi
 
 
@@ -14367,7 +14159,7 @@ elif test $pkg_failed = untried; then
         { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
 
-		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse_main in -losxfuse" >&5
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse_main in -losxfuse" >&5
 printf %s "checking for fuse_main in -losxfuse... " >&6; }
 if test ${ac_cv_lib_osxfuse_fuse_main+y}
 then :
@@ -14405,8 +14197,6 @@ printf "%s\n" "$ac_cv_lib_osxfuse_fuse_main" >&6; }
 if test "x$ac_cv_lib_osxfuse_fuse_main" = xyes
 then :
   FUSE_LIB=-losxfuse
-else $as_nop
-  FUSE_CMT="#"
 fi
 
 
@@ -14417,15 +14207,6 @@ else
 printf "%s\n" "yes" >&6; }
         FUSE_LIB=-lfuse3
 fi
-	if test -z "$FUSE_CMT"
-	then
-		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Enabling fuse2fs by default." >&5
-printf "%s\n" "Enabling fuse2fs by default." >&6; }
-	fi
-
-
-fi
-
 
 
 if test -n "$FUSE_LIB"
@@ -14437,12 +14218,7 @@ then
 do :
   as_ac_Header=`printf "%s\n" "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "#define _FILE_OFFSET_BITS	64
-#define FUSE_USE_VERSION 314
-#ifdef __linux__
-#include <linux/fs.h>
-#include <linux/falloc.h>
-#include <linux/xattr.h>
-#endif
+#define FUSE_USE_VERSION	314
 "
 if eval test \"x\$"$as_ac_Header"\" = x"yes"
 then :
@@ -14453,7 +14229,7 @@ _ACEOF
 else $as_nop
   { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
 printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "Cannot find fuse3 fuse2fs headers.
+as_fn_error $? "Cannot build against fuse3 headers
 See \`config.log' for more details" "$LINENO" 5; }
 fi
 
@@ -14466,6 +14242,71 @@ printf "%s\n" "#define FUSE_USE_VERSION $FUSE_USE_VERSION" >>confdefs.h
 
 fi
 
+FUSE2FS_CMT=
+# Check whether --enable-fuse2fs was given.
+if test ${enable_fuse2fs+y}
+then :
+  enableval=$enable_fuse2fs;
+	if test "$enableval" = "no"
+	then
+		FUSE2FS_CMT="#"
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Disabling fuse2fs" >&5
+printf "%s\n" "Disabling fuse2fs" >&6; }
+	else
+		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#ifdef __linux__
+	#include <linux/fs.h>
+	#include <linux/falloc.h>
+	#include <linux/xattr.h>
+	#endif
+
+int
+main (void)
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_cpp "$LINENO"
+then :
+
+else $as_nop
+  { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "Cannot find fuse2fs Linux headers
+See \`config.log' for more details" "$LINENO" 5; }
+fi
+rm -f conftest.err conftest.i conftest.$ac_ext
+
+		if test -z "$FUSE_USE_VERSION"
+		then
+			{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "Cannot find fuse library.
+See \`config.log' for more details" "$LINENO" 5; }
+		fi
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Enabling fuse2fs" >&5
+printf "%s\n" "Enabling fuse2fs" >&6; }
+	fi
+
+else $as_nop
+
+	if test -n "$FUSE_USE_VERSION"
+	then
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Enabling fuse2fs by default" >&5
+printf "%s\n" "Enabling fuse2fs by default" >&6; }
+	else
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Disabling fuse2fs by default" >&5
+printf "%s\n" "Disabling fuse2fs by default" >&6; }
+	fi
+
+
+fi
+
+
+
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for PR_SET_IO_FLUSHER" >&5
 printf %s "checking for PR_SET_IO_FLUSHER... " >&6; }
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
diff --git a/configure.ac b/configure.ac
index bf1b57377cd848..b40ed1456d1515 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1366,18 +1366,48 @@ dnl Check to see if librt is required for clock_gettime() (glibc < 2.17)
 dnl
 AC_CHECK_LIB(rt, clock_gettime, [CLOCK_GETTIME_LIB=-lrt])
 AC_SUBST(CLOCK_GETTIME_LIB)
+
 dnl
 dnl Check to see if the FUSE library is -lfuse3 or -losxfuse
 dnl
-FUSE_CMT=
 FUSE_LIB=
 dnl osxfuse.dylib supersedes fuselib.dylib
+PKG_CHECK_MODULES([fuse3], [fuse3], [FUSE_LIB=-lfuse3],
+[
+	AC_CHECK_LIB(osxfuse, fuse_main, [FUSE_LIB=-losxfuse])
+])
+AC_SUBST(FUSE_LIB)
+
+dnl
+dnl Set FUSE_USE_VERSION, which is how fuse servers build against a particular
+dnl libfuse ABI.  Currently we link against the libfuse 3.14 ABI (hence 314)
+dnl
+if test -n "$FUSE_LIB"
+then
+	FUSE_USE_VERSION=314
+	CFLAGS="$fuse3_CFLAGS $CFLAGS"
+	FUSE_LIB="$fuse3_LIBS"
+	AC_CHECK_HEADERS([pthread.h fuse.h], [],
+		[AC_MSG_FAILURE([Cannot build against fuse3 headers])],
+[#define _FILE_OFFSET_BITS	64
+#define FUSE_USE_VERSION	314])
+fi
+if test -n "$FUSE_USE_VERSION"
+then
+	AC_DEFINE_UNQUOTED(FUSE_USE_VERSION, $FUSE_USE_VERSION,
+		[Define to the version of FUSE to use])
+fi
+
+dnl
+dnl Check if fuse2fs is actually built.
+dnl
+FUSE2FS_CMT=
 AC_ARG_ENABLE([fuse2fs],
 AS_HELP_STRING([--disable-fuse2fs],[do not build fuse2fs]),
 [
 	if test "$enableval" = "no"
 	then
-		FUSE_CMT="#"
+		FUSE2FS_CMT="#"
 		AC_MSG_RESULT([Disabling fuse2fs])
 	else
 		AC_PREPROC_IFELSE(
@@ -1386,49 +1416,24 @@ AS_HELP_STRING([--disable-fuse2fs],[do not build fuse2fs]),
 	#include <linux/falloc.h>
 	#include <linux/xattr.h>
 	#endif
-	]], [])], [], [AC_MSG_FAILURE([Cannot find fuse2fs Linux headers.])])
+	]], [])], [], [AC_MSG_FAILURE([Cannot find fuse2fs Linux headers])])
 
-		PKG_CHECK_MODULES([fuse3], [fuse3], [FUSE_LIB=-lfuse3],
-		[
-			AC_CHECK_LIB(osxfuse, fuse_main, [FUSE_LIB=-losxfuse],
-				[AC_MSG_FAILURE([Cannot find fuse library.])])
-		])
+		if test -z "$FUSE_USE_VERSION"
+		then
+			AC_MSG_FAILURE([Cannot find fuse library.])
+		fi
 		AC_MSG_RESULT([Enabling fuse2fs])
 	fi
 ], [
-	PKG_CHECK_MODULES([fuse3], [fuse3], [FUSE_LIB=-lfuse3],
-	[
-		AC_CHECK_LIB(osxfuse, fuse_main, [FUSE_LIB=-losxfuse],
-			[FUSE_CMT="#"])
-	])
-	if test -z "$FUSE_CMT"
+	if test -n "$FUSE_USE_VERSION"
 	then
-		AC_MSG_RESULT([Enabling fuse2fs by default.])
+		AC_MSG_RESULT([Enabling fuse2fs by default])
+	else
+		AC_MSG_RESULT([Disabling fuse2fs by default])
 	fi
 ]
 )
-AC_SUBST(FUSE_LIB)
-AC_SUBST(FUSE_CMT)
-if test -n "$FUSE_LIB"
-then
-	FUSE_USE_VERSION=314
-	CFLAGS="$fuse3_CFLAGS $CFLAGS"
-	FUSE_LIB="$fuse3_LIBS"
-	AC_CHECK_HEADERS([pthread.h fuse.h], [],
-		[AC_MSG_FAILURE([Cannot find fuse3 fuse2fs headers.])],
-[#define _FILE_OFFSET_BITS	64
-#define FUSE_USE_VERSION 314
-#ifdef __linux__
-#include <linux/fs.h>
-#include <linux/falloc.h>
-#include <linux/xattr.h>
-#endif])
-fi
-if test -n "$FUSE_USE_VERSION"
-then
-	AC_DEFINE_UNQUOTED(FUSE_USE_VERSION, $FUSE_USE_VERSION,
-		[Define to the version of FUSE to use])
-fi
+AC_SUBST(FUSE2FS_CMT)
 
 dnl
 dnl see if PR_SET_IO_FLUSHER exists
diff --git a/misc/Makefile.in b/misc/Makefile.in
index 0e3bed66dcb63d..b63a0424b19fec 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -34,7 +34,7 @@ MKDIR_P = @MKDIR_P@
 @BLKID_CMT@FINDFS_LINK= findfs
 @BLKID_CMT@FINDFS_MAN= findfs.8
 
-@FUSE_CMT@FUSE_PROG= fuse2fs
+@FUSE2FS_CMT@FUSE2FS_PROG= fuse2fs
 
 SPROGS=		mke2fs badblocks tune2fs dumpe2fs $(BLKID_PROG) logsave \
 			$(E2IMAGE_PROG) @FSCK_PROG@ e2undo
@@ -47,9 +47,9 @@ SMANPAGES=	tune2fs.8 mklost+found.8 mke2fs.8 dumpe2fs.8 badblocks.8 \
 			e2mmpstatus.8
 FMANPAGES=	mke2fs.conf.5 ext4.5
 
-UPROGS=		chattr lsattr $(FUSE_PROG) @UUID_CMT@ uuidgen
+UPROGS=		chattr lsattr $(FUSE2FS_PROG) @UUID_CMT@ uuidgen
 UMANPAGES=	chattr.1 lsattr.1 @UUID_CMT@ uuidgen.1
-UMANPAGES+=	@FUSE_CMT@ fuse2fs.1
+UMANPAGES+=	@FUSE2FS_CMT@ fuse2fs.1
 
 LPROGS=		@E2INITRD_PROG@
 

[PATCH 02/21] fuse2fs: start porting fuse2fs to lowlevel libfuse API

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Copy fuse2fs.c to fuse4fs.c.  This will become our testbed for trying
out lowlevel fuse server support in the next few patches.

Namespacing conversions performed via:
sed -e 's/fuse2fs/fuse4fs/g' -e 's/FUSE2FS/FUSE4FS/g' -e 's/F2OP_/F4OP_/g' -e 's/FUSE server/FUSE low-level server/g'

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 Makefile.in          |    3 
 configure            |  113 +
 configure.ac         |   65 +
 fuse4fs/Makefile.in  |  192 ++
 fuse4fs/fuse4fs.1.in |  118 +
 fuse4fs/fuse4fs.c    | 5516 ++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/config.h.in      |    3 
 7 files changed, 6007 insertions(+), 3 deletions(-)
 create mode 100644 fuse4fs/Makefile.in
 create mode 100644 fuse4fs/fuse4fs.1.in
 create mode 100644 fuse4fs/fuse4fs.c


diff --git a/Makefile.in b/Makefile.in
index 277b500bbc9acc..d000f94bc88f0f 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -18,12 +18,13 @@ MKDIR_P = @MKDIR_P@
 @ALL_CMT@SUPPORT_LIB_SUBDIR= lib/support
 @ALL_CMT@E2P_LIB_SUBDIR= lib/e2p
 @ALL_CMT@EXT2FS_LIB_SUBDIR= lib/ext2fs
+@FUSE4FS_CMT@FUSE4FS_DIR=fuse4fs
 
 LIB_SUBDIRS=lib/et lib/ss $(E2P_LIB_SUBDIR) $(UUID_LIB_SUBDIR) \
 	$(BLKID_LIB_SUBDIR) $(SUPPORT_LIB_SUBDIR) $(EXT2FS_LIB_SUBDIR)
 
 PROG_SUBDIRS=e2fsck $(DEBUGFS_DIR) misc $(RESIZE_DIR) tests/progs \
-	tests/fuzz po $(E2SCRUB_DIR)
+	tests/fuzz po $(E2SCRUB_DIR) $(FUSE4FS_DIR)
 
 SUBDIRS=util $(LIB_SUBDIRS) $(PROG_SUBDIRS) tests
 
diff --git a/configure b/configure
index 22031343f078ab..7f5fb7c1a62084 100755
--- a/configure
+++ b/configure
@@ -701,6 +701,7 @@ gcc_ranlib
 gcc_ar
 UNI_DIFF_OPTS
 SEM_INIT_LIB
+FUSE4FS_CMT
 FUSE2FS_CMT
 FUSE_LIB
 fuse3_LIBS
@@ -933,6 +934,7 @@ with_libintl_prefix
 enable_largefile
 with_libarchive
 enable_fuse2fs
+enable_fuse4fs
 enable_lto
 enable_ubsan
 enable_addrsan
@@ -1628,6 +1630,7 @@ Optional Features:
   --disable-rpath         do not hardcode runtime library paths
   --disable-largefile     omit support for large files
   --disable-fuse2fs       do not build fuse2fs
+  --disable-fuse4fs       do not build fuse4fs
   --enable-lto            enable link time optimization
   --enable-ubsan          enable undefined behavior sanitizer
   --enable-addrsan        enable address sanitizer
@@ -14242,6 +14245,49 @@ printf "%s\n" "#define FUSE_USE_VERSION $FUSE_USE_VERSION" >>confdefs.h
 
 fi
 
+have_fuse_lowlevel=
+if test -n "$FUSE_USE_VERSION"
+then
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for lowlevel interface in libfuse" >&5
+printf %s "checking for lowlevel interface in libfuse... " >&6; }
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+	#define _GNU_SOURCE
+	#define _FILE_OFFSET_BITS	64
+	#define FUSE_USE_VERSION	314
+	#include <fuse_lowlevel.h>
+
+int
+main (void)
+{
+
+	struct fuse_lowlevel_ops fs_ops = { };
+
+  ;
+  return 0;
+}
+
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  have_fuse_lowlevel=yes
+	   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; }
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+if test -n "$have_fuse_lowlevel"
+then
+
+printf "%s\n" "#define HAVE_FUSE_LOWLEVEL 1" >>confdefs.h
+
+fi
+
 FUSE2FS_CMT=
 # Check whether --enable-fuse2fs was given.
 if test ${enable_fuse2fs+y}
@@ -14307,6 +14353,71 @@ fi
 
 
 
+FUSE4FS_CMT=
+# Check whether --enable-fuse4fs was given.
+if test ${enable_fuse4fs+y}
+then :
+  enableval=$enable_fuse4fs;
+	if test "$enableval" = "no"
+	then
+		FUSE4FS_CMT="#"
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Disabling fuse4fs" >&5
+printf "%s\n" "Disabling fuse4fs" >&6; }
+	else
+		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#ifdef __linux__
+	#include <linux/fs.h>
+	#include <linux/falloc.h>
+	#include <linux/xattr.h>
+	#endif
+
+int
+main (void)
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_cpp "$LINENO"
+then :
+
+else $as_nop
+  { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "Cannot find fuse4fs Linux headers
+See \`config.log' for more details" "$LINENO" 5; }
+fi
+rm -f conftest.err conftest.i conftest.$ac_ext
+
+		if test -z "$have_fuse_lowlevel"
+		then
+			{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "Cannot find fuse lowlevel library.
+See \`config.log' for more details" "$LINENO" 5; }
+		fi
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Enabling fuse4fs" >&5
+printf "%s\n" "Enabling fuse4fs" >&6; }
+	fi
+
+else $as_nop
+
+	if test -n "$have_fuse_lowlevel"
+	then
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Enabling fuse4fs by default" >&5
+printf "%s\n" "Enabling fuse4fs by default" >&6; }
+	else
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: Disabling fuse4fs by default" >&5
+printf "%s\n" "Disabling fuse4fs by default" >&6; }
+	fi
+
+
+fi
+
+
+
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for PR_SET_IO_FLUSHER" >&5
 printf %s "checking for PR_SET_IO_FLUSHER... " >&6; }
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -15984,7 +16095,7 @@ for i in MCONFIG Makefile \
 	misc/Makefile ext2ed/Makefile e2fsck/Makefile \
 	debugfs/Makefile tests/Makefile tests/progs/Makefile \
 	tests/fuzz/Makefile resize/Makefile doc/Makefile \
-	po/Makefile.in scrub/Makefile; do
+	po/Makefile.in scrub/Makefile fuse4fs/Makefile; do
 	if test -d `dirname ${srcdir}/$i` ; then
 		outlist="$outlist $i"
 	fi
diff --git a/configure.ac b/configure.ac
index b40ed1456d1515..2eb11873ea0e50 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1398,6 +1398,32 @@ then
 		[Define to the version of FUSE to use])
 fi
 
+dnl
+dnl Check if the FUSE lowlevel library is supported
+dnl
+have_fuse_lowlevel=
+if test -n "$FUSE_USE_VERSION"
+then
+	AC_MSG_CHECKING(for lowlevel interface in libfuse)
+	AC_LINK_IFELSE(
+	[	AC_LANG_PROGRAM([[
+	#define _GNU_SOURCE
+	#define _FILE_OFFSET_BITS	64
+	#define FUSE_USE_VERSION	314
+	#include <fuse_lowlevel.h>
+		]], [[
+	struct fuse_lowlevel_ops fs_ops = { };
+		]])
+	], have_fuse_lowlevel=yes
+	   AC_MSG_RESULT(yes),
+	   AC_MSG_RESULT(no))
+fi
+if test -n "$have_fuse_lowlevel"
+then
+	AC_DEFINE(HAVE_FUSE_LOWLEVEL, 1,
+		  [Define to 1 if fuse supports lowlevel API])
+fi
+
 dnl
 dnl Check if fuse2fs is actually built.
 dnl
@@ -1435,6 +1461,43 @@ AS_HELP_STRING([--disable-fuse2fs],[do not build fuse2fs]),
 )
 AC_SUBST(FUSE2FS_CMT)
 
+dnl
+dnl Check if fuse4fs is actually built.
+dnl
+FUSE4FS_CMT=
+AC_ARG_ENABLE([fuse4fs],
+AS_HELP_STRING([--disable-fuse4fs],[do not build fuse4fs]),
+[
+	if test "$enableval" = "no"
+	then
+		FUSE4FS_CMT="#"
+		AC_MSG_RESULT([Disabling fuse4fs])
+	else
+		AC_PREPROC_IFELSE(
+	[AC_LANG_PROGRAM([[#ifdef __linux__
+	#include <linux/fs.h>
+	#include <linux/falloc.h>
+	#include <linux/xattr.h>
+	#endif
+	]], [])], [], [AC_MSG_FAILURE([Cannot find fuse4fs Linux headers])])
+
+		if test -z "$have_fuse_lowlevel"
+		then
+			AC_MSG_FAILURE([Cannot find fuse lowlevel library.])
+		fi
+		AC_MSG_RESULT([Enabling fuse4fs])
+	fi
+], [
+	if test -n "$have_fuse_lowlevel"
+	then
+		AC_MSG_RESULT([Enabling fuse4fs by default])
+	else
+		AC_MSG_RESULT([Disabling fuse4fs by default])
+	fi
+]
+)
+AC_SUBST(FUSE4FS_CMT)
+
 dnl
 dnl see if PR_SET_IO_FLUSHER exists
 dnl
@@ -2042,7 +2105,7 @@ for i in MCONFIG Makefile \
 	misc/Makefile ext2ed/Makefile e2fsck/Makefile \
 	debugfs/Makefile tests/Makefile tests/progs/Makefile \
 	tests/fuzz/Makefile resize/Makefile doc/Makefile \
-	po/Makefile.in scrub/Makefile; do
+	po/Makefile.in scrub/Makefile fuse4fs/Makefile; do
 	if test -d `dirname ${srcdir}/$i` ; then
 		outlist="$outlist $i"
 	fi
diff --git a/fuse4fs/Makefile.in b/fuse4fs/Makefile.in
new file mode 100644
index 00000000000000..bc137a765ee2b7
--- /dev/null
+++ b/fuse4fs/Makefile.in
@@ -0,0 +1,192 @@
+#
+# Standard e2fsprogs prologue....
+#
+
+srcdir = @srcdir@
+top_srcdir = @top_srcdir@
+VPATH = @srcdir@
+top_builddir = ..
+my_dir = misc
+INSTALL = @INSTALL@
+MKDIR_P = @MKDIR_P@
+
+@MCONFIG@
+
+UPROGS=
+UMANPAGES=
+@FUSE4FS_CMT@UPROGS+=fuse4fs
+@FUSE4FS_CMT@UMANPAGES+=fuse4fs.1
+
+FUSE4FS_OBJS=	fuse4fs.o journal.o recovery.o revoke.o
+
+PROFILED_FUSE4FS_OJBS=	profiled/fuse4fs.o profiled/journal.o \
+			profiled/recovery.o profiled/revoke.o
+
+SRCS=\
+	$(srcdir)/fuse4fs.c \
+	$(srcdir)/../debugfs/journal.c \
+	$(srcdir)/../e2fsck/revoke.c \
+	$(srcdir)/../e2fsck/recovery.c
+
+LIBS= $(LIBEXT2FS) $(LIBCOM_ERR) $(LIBSUPPORT)
+DEPLIBS= $(LIBEXT2FS) $(DEPLIBCOM_ERR) $(DEPLIBSUPPORT)
+PROFILED_LIBS= $(LIBSUPPORT) $(PROFILED_LIBEXT2FS) $(PROFILED_LIBCOM_ERR)
+PROFILED_DEPLIBS= $(DEPLIBSUPPORT) $(PROFILED_LIBEXT2FS) $(DEPPROFILED_LIBCOM_ERR)
+
+STATIC_LIBS= $(LIBSUPPORT) $(STATIC_LIBEXT2FS) $(STATIC_LIBCOM_ERR)
+STATIC_DEPLIBS= $(DEPLIBSUPPORT) $(STATIC_LIBEXT2FS) $(DEPSTATIC_LIBCOM_ERR)
+
+LIBS_E2P= $(LIBE2P) $(LIBCOM_ERR)
+DEPLIBS_E2P= $(LIBE2P) $(DEPLIBCOM_ERR)
+
+COMPILE_ET=	_ET_DIR_OVERRIDE=$(srcdir)/../lib/et/et ../lib/et/compile_et
+
+# This nastiness is needed because of jfs_user.h hackery; when we finally
+# clean up this mess, we should be able to drop it
+JOURNAL_CFLAGS = -I$(srcdir)/../e2fsck $(ALL_CFLAGS) -DDEBUGFS
+DEPEND_CFLAGS = -I$(top_srcdir)/e2fsck
+
+.c.o:
+	$(E) "	CC $<"
+	$(Q) $(CC) -c $(ALL_CFLAGS) $< -o $@
+	$(Q) $(CHECK_CMD) $(ALL_CFLAGS) $<
+	$(Q) $(CPPCHECK_CMD) $(CPPFLAGS) $<
+@PROFILE_CMT@	$(Q) $(CC) $(ALL_CFLAGS) -g -pg -o profiled/$*.o -c $<
+
+all:: profiled $(SPROGS) $(UPROGS) $(USPROGS) $(SMANPAGES) $(UMANPAGES) \
+	$(FMANPAGES) $(LPROGS)
+
+all-static::
+
+@PROFILE_CMT@all:: fuse4fs.profiled
+
+profiled:
+@PROFILE_CMT@	$(E) "	MKDIR $@"
+@PROFILE_CMT@	$(Q) mkdir profiled
+
+fuse4fs: $(FUSE4FS_OBJS) $(DEPLIBS) $(DEPLIBBLKID) $(DEPLIBUUID) \
+		$(LIBEXT2FS) $(DEPLIBS_E2P)
+	$(E) "	LD $@"
+	$(Q) $(CC) $(ALL_LDFLAGS) -o fuse4fs $(FUSE4FS_OBJS) $(LIBS) \
+		$(LIBFUSE) $(LIBBLKID) $(LIBUUID) $(LIBEXT2FS) $(LIBINTL) \
+		$(CLOCK_GETTIME_LIB) $(SYSLIBS) $(LIBS_E2P)
+
+journal.o: $(srcdir)/../debugfs/journal.c
+	$(E) "	CC $<"
+	$(Q) $(CC) -c $(JOURNAL_CFLAGS) -I$(srcdir) \
+		$(srcdir)/../debugfs/journal.c -o $@
+@PROFILE_CMT@	$(Q) $(CC) $(JOURNAL_CFLAGS) -g -pg -o profiled/$*.o -c $<
+
+recovery.o: $(srcdir)/../e2fsck/recovery.c
+	$(E) "	CC $<"
+	$(Q) $(CC) -c $(JOURNAL_CFLAGS) -I$(srcdir) \
+		$(srcdir)/../e2fsck/recovery.c -o $@
+@PROFILE_CMT@	$(Q) $(CC) $(JOURNAL_CFLAGS) -g -pg -o profiled/$*.o -c $<
+
+revoke.o: $(srcdir)/../e2fsck/revoke.c
+	$(E) "	CC $<"
+	$(Q) $(CC) -c $(JOURNAL_CFLAGS) -I$(srcdir) \
+		$(srcdir)/../e2fsck/revoke.c -o $@
+@PROFILE_CMT@	$(Q) $(CC) $(JOURNAL_CFLAGS) -g -pg -o profiled/$*.o -c $<
+
+fuse4fs.1: $(DEP_SUBSTITUTE) $(srcdir)/fuse4fs.1.in
+	$(E) "	SUBST $@"
+	$(Q) $(SUBSTITUTE_UPTIME) $(srcdir)/fuse4fs.1.in fuse4fs.1
+
+installdirs:
+	$(E) "	MKDIR_P $(bindir) $(man1dir)"
+	$(Q) $(MKDIR_P) $(DESTDIR)$(bindir) $(DESTDIR)$(man1dir)
+
+install: all $(UMANPAGES) installdirs
+	$(Q) for i in $(UPROGS); do \
+		$(ES) "	INSTALL $(bindir)/$$i"; \
+		$(INSTALL_PROGRAM) $$i $(DESTDIR)$(bindir)/$$i; \
+	done
+	$(Q) for i in $(UMANPAGES); do \
+		for j in $(COMPRESS_EXT); do \
+			$(RM) -f $(DESTDIR)$(man1dir)/$$i.$$j; \
+		done; \
+		$(ES) "	INSTALL_DATA $(man1dir)/$$i"; \
+		$(INSTALL_DATA) $$i $(DESTDIR)$(man1dir)/$$i; \
+	done
+
+install-strip: install
+	$(Q) for i in $(UPROGS); do \
+		$(E) "	STRIP $(bindir)/$$i"; \
+		$(STRIP) $(DESTDIR)$(bindir)/$$i; \
+	done
+
+uninstall:
+	for i in $(UPROGS); do \
+		$(RM) -f $(DESTDIR)$(bindir)/$$i; \
+	done
+	for i in $(UMANPAGES); do \
+		$(RM) -f $(DESTDIR)$(man1dir)/$$i; \
+	done
+
+clean::
+	$(RM) -f $(UPROGS) $(UMANPAGES) profile.h \
+		fuse4fs.profiled \
+		profiled/*.o \#* *.s *.o *.a *~ core gmon.out
+
+mostlyclean: clean
+distclean: clean
+	$(RM) -f .depend Makefile $(srcdir)/TAGS $(srcdir)/Makefile.in.old
+
+# +++ Dependency line eater +++
+#
+# Makefile dependencies follow.  This must be the last section in
+# the Makefile.in file
+#
+fuse4fs.o: $(srcdir)/fuse4fs.c $(top_builddir)/lib/config.h \
+ $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/ext2fs/ext2fs.h \
+ $(top_builddir)/lib/ext2fs/ext2_types.h $(top_srcdir)/lib/ext2fs/ext2_fs.h \
+ $(top_srcdir)/lib/ext2fs/ext3_extents.h $(top_srcdir)/lib/et/com_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
+ $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/ext2fsP.h \
+ $(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/version.h \
+ $(top_srcdir)/lib/e2p/e2p.h
+journal.o: $(srcdir)/../debugfs/journal.c $(top_builddir)/lib/config.h \
+ $(top_builddir)/lib/dirpaths.h $(srcdir)/../debugfs/journal.h \
+ $(top_srcdir)/e2fsck/jfs_user.h $(top_srcdir)/e2fsck/e2fsck.h \
+ $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
+ $(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/lib/ext2fs/ext3_extents.h \
+ $(top_srcdir)/lib/et/com_err.h $(top_srcdir)/lib/ext2fs/ext2_io.h \
+ $(top_builddir)/lib/ext2fs/ext2_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
+ $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/support/profile.h \
+ $(top_builddir)/lib/support/prof_err.h $(top_srcdir)/lib/support/quotaio.h \
+ $(top_srcdir)/lib/support/dqblk_v2.h \
+ $(top_srcdir)/lib/support/quotaio_tree.h \
+ $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
+ $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/ext2fs/kernel-jbd.h
+revoke.o: $(srcdir)/../e2fsck/revoke.c $(srcdir)/../e2fsck/jfs_user.h \
+ $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
+ $(srcdir)/../e2fsck/e2fsck.h $(top_srcdir)/lib/ext2fs/ext2_fs.h \
+ $(top_builddir)/lib/ext2fs/ext2_types.h $(top_srcdir)/lib/ext2fs/ext2fs.h \
+ $(top_srcdir)/lib/ext2fs/ext3_extents.h $(top_srcdir)/lib/et/com_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
+ $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/support/profile.h \
+ $(top_builddir)/lib/support/prof_err.h $(top_srcdir)/lib/support/quotaio.h \
+ $(top_srcdir)/lib/support/dqblk_v2.h \
+ $(top_srcdir)/lib/support/quotaio_tree.h \
+ $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
+ $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/ext2fs/kernel-jbd.h
+recovery.o: $(srcdir)/../e2fsck/recovery.c $(srcdir)/../e2fsck/jfs_user.h \
+ $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
+ $(srcdir)/../e2fsck/e2fsck.h $(top_srcdir)/lib/ext2fs/ext2_fs.h \
+ $(top_builddir)/lib/ext2fs/ext2_types.h $(top_srcdir)/lib/ext2fs/ext2fs.h \
+ $(top_srcdir)/lib/ext2fs/ext3_extents.h $(top_srcdir)/lib/et/com_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
+ $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/support/profile.h \
+ $(top_builddir)/lib/support/prof_err.h $(top_srcdir)/lib/support/quotaio.h \
+ $(top_srcdir)/lib/support/dqblk_v2.h \
+ $(top_srcdir)/lib/support/quotaio_tree.h \
+ $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
+ $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/ext2fs/kernel-jbd.h
diff --git a/fuse4fs/fuse4fs.1.in b/fuse4fs/fuse4fs.1.in
new file mode 100644
index 00000000000000..8bef5f48802385
--- /dev/null
+++ b/fuse4fs/fuse4fs.1.in
@@ -0,0 +1,118 @@
+.\" -*- nroff -*-
+.\" Copyright 2025 Oracle.  All Rights Reserved.
+.\" This file may be copied under the terms of the GNU Public License.
+.\"
+.TH FUSE4FS 1 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
+.SH NAME
+fuse4fs \- FUSE file system client for ext2/ext3/ext4 file systems
+.SH SYNOPSIS
+.B fuse4fs
+[
+.B device/image
+]
+[
+.B mountpoint
+]
+[
+.I options
+]
+.SH DESCRIPTION
+.B fuse4fs
+is a FUSE file system client that supports reading and writing from
+devices or image files containing ext2, ext3, and ext4 file systems.
+.SH OPTIONS
+.SS "general options:"
+.TP
+\fB\-o\fR opt,[opt...]
+mount options
+.TP
+\fB\-h\fR   \fB\-\-help\fR
+print help
+.TP
+\fB\-V\fR   \fB\-\-version\fR
+print version
+.SS "fuse4fs options:"
+.TP
+\fB-o\fR ro
+read-only mount
+.TP
+\fB-o\fR rw
+read-write mount (default)
+.TP
+\fB-o\fR bsddf
+bsd-style df (default)
+.TP
+\fB-o\fR minixdf
+minix-style df
+.TP
+\fB-o\fR acl
+enable file access control lists
+.TP
+\fB-o\fR cache_size
+Set the disk cache size to this quantity.
+The quantity may contain the suffixes k, m, or g.
+By default, the size is 32MB.
+The size may not be larger than 2GB.
+.TP
+\fB-o\fR direct
+Use O_DIRECT to access the block device.
+.TP
+\fB-o\fR dirsync
+Flush dirty metadata to disk after every directory update.
+.TP
+\fB-o\fR errors=continue
+ignore errors
+.TP
+\fB-o\fR errors=remount-ro
+stop allowing writes after errors
+.TP
+\fB-o\fR errors=panic
+dump core on error
+.TP
+\fB-o\fR fakeroot
+pretend to be root for permission checks
+.TP
+\fB-o\fR fuse4fs_debug
+enable fuse4fs debugging
+.TP
+\fB-o\fR kernel
+Behave more like the kernel ext4 driver in the following ways:
+Allows processes owned by other users to access the filesystem.
+Uses the kernel's permissions checking logic instead of fuse4fs's.
+Enables setuid and device files.
+Note that these options can still be overridden (e.g.
+.I nosuid
+) later.
+.TP
+\fB-o\fR lockfile=path
+use this file to control access to the filesystem
+.TP
+\fB-o\fR no_default_opts
+do not include default fuse options
+.TP
+\fB-o\fR norecovery
+do not replay the journal and mount the file system read-only
+.SS "FUSE options:"
+.TP
+\fB-d -o\fR debug
+enable debug output (implies -f)
+.TP
+\fB-f\fR
+foreground operation
+.TP
+\fB-s\fR
+disable multi-threaded operation
+.P
+For other FUSE options please see
+.BR mount.fuse (8)
+or see the output of
+.I fuse4fs \-\-helpfull
+.SH AVAILABILITY
+.B fuse4fs
+is part of the e2fsprogs package and is available from
+http://e2fsprogs.sourceforge.net.
+.SH SEE ALSO
+.BR ext4 (5)
+.BR e2fsck (8),
+.BR mount.fuse (8)
+
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
new file mode 100644
index 00000000000000..99b9b902b37a57
--- /dev/null
+++ b/fuse4fs/fuse4fs.c
@@ -0,0 +1,5516 @@
+/*
+ * fuse4fs.c - FUSE low-level server for e2fsprogs.
+ *
+ * Copyright (C) 2014-2025 Oracle.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include "config.h"
+#include <pthread.h>
+#ifdef __linux__
+# include <linux/fs.h>
+# include <linux/falloc.h>
+# include <linux/xattr.h>
+# include <sys/prctl.h>
+#endif
+#ifdef HAVE_SYS_XATTR_H
+#include <sys/xattr.h>
+#endif
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <stdbool.h>
+#define FUSE_DARWIN_ENABLE_EXTENSIONS 0
+#ifdef __SET_FOB_FOR_FUSE
+# error Do not set magic value __SET_FOB_FOR_FUSE!!!!
+#endif
+#ifndef _FILE_OFFSET_BITS
+/*
+ * Old versions of libfuse (e.g. Debian 2.9.9 package) required that the build
+ * system set _FILE_OFFSET_BITS explicitly, even if doing so isn't required to
+ * get a 64-bit off_t.  AC_SYS_LARGEFILE doesn't set any _FILE_OFFSET_BITS if
+ * it's not required (such as on aarch64), so we must inject it here.
+ */
+# define __SET_FOB_FOR_FUSE
+# define _FILE_OFFSET_BITS 64
+#endif /* _FILE_OFFSET_BITS */
+#include <fuse.h>
+#ifdef __SET_FOB_FOR_FUSE
+# undef _FILE_OFFSET_BITS
+#endif /* __SET_FOB_FOR_FUSE */
+#include <inttypes.h>
+#include "ext2fs/ext2fs.h"
+#include "ext2fs/ext2_fs.h"
+#include "ext2fs/ext2fsP.h"
+
+#include "../version.h"
+#include "uuid/uuid.h"
+#include "e2p/e2p.h"
+
+#ifdef ENABLE_NLS
+#include <libintl.h>
+#include <locale.h>
+#define _(a) (gettext(a))
+#ifdef gettext_noop
+#define N_(a) gettext_noop(a)
+#else
+#define N_(a) (a)
+#endif
+#define P_(singular, plural, n) (ngettext(singular, plural, n))
+#ifndef NLS_CAT_NAME
+#define NLS_CAT_NAME "e2fsprogs"
+#endif
+#ifndef LOCALEDIR
+#define LOCALEDIR "/usr/share/locale"
+#endif
+#else
+#define _(a) (a)
+#define N_(a) a
+#define P_(singular, plural, n) ((n) == 1 ? (singular) : (plural))
+#endif
+
+#ifndef XATTR_NAME_POSIX_ACL_DEFAULT
+#define XATTR_NAME_POSIX_ACL_DEFAULT "posix_acl_default"
+#endif
+#ifndef XATTR_SECURITY_PREFIX
+#define XATTR_SECURITY_PREFIX "security."
+#define XATTR_SECURITY_PREFIX_LEN (sizeof (XATTR_SECURITY_PREFIX) - 1)
+#endif
+
+/*
+ * Linux and MacOS implement the setxattr(2) interface, which defines
+ * XATTR_CREATE and XATTR_REPLACE.  However, FreeBSD uses
+ * extattr_set_file(2), which does not have a flags or options
+ * parameter, and does not define XATTR_CREATE and XATTR_REPLACE.
+ */
+#ifndef XATTR_CREATE
+#define XATTR_CREATE 0
+#endif
+
+#ifndef XATTR_REPLACE
+#define XATTR_REPLACE 0
+#endif
+
+#if !defined(EUCLEAN)
+#if !defined(EBADMSG)
+#define EUCLEAN EBADMSG
+#elif !defined(EPROTO)
+#define EUCLEAN EPROTO
+#else
+#define EUCLEAN EIO
+#endif
+#endif /* !defined(EUCLEAN) */
+
+#if !defined(ENODATA)
+#ifdef ENOATTR
+#define ENODATA ENOATTR
+#else
+#define ENODATA ENOENT
+#endif
+#endif /* !defined(ENODATA) */
+
+static inline uint64_t round_up(uint64_t b, unsigned int align)
+{
+	unsigned int m;
+
+	if (align == 0)
+		return b;
+	m = b % align;
+	if (m)
+		b += align - m;
+	return b;
+}
+
+static inline uint64_t round_down(uint64_t b, unsigned int align)
+{
+	unsigned int m;
+
+	if (align == 0)
+		return b;
+	m = b % align;
+	return b - m;
+}
+
+#define dbg_printf(fuse4fs, format, ...) \
+	while ((fuse4fs)->debug) { \
+		printf("FUSE4FS (%s): tid=%d " format, (fuse4fs)->shortdev, gettid(), ##__VA_ARGS__); \
+		fflush(stdout); \
+		break; \
+	}
+
+#define log_printf(fuse4fs, format, ...) \
+	do { \
+		printf("FUSE4FS (%s): " format, (fuse4fs)->shortdev, ##__VA_ARGS__); \
+		fflush(stdout); \
+	} while (0)
+
+#define err_printf(fuse4fs, format, ...) \
+	do { \
+		fprintf(stderr, "FUSE4FS (%s): " format, (fuse4fs)->shortdev, ##__VA_ARGS__); \
+		fflush(stderr); \
+	} while (0)
+
+#define timing_printf(fuse4fs, format, ...) \
+	while ((fuse4fs)->timing) { \
+		printf("FUSE4FS (%s): " format, (fuse4fs)->shortdev, ##__VA_ARGS__); \
+		break; \
+	}
+
+#ifdef _IOR
+# ifdef _IOW
+#  define SUPPORT_I_FLAGS
+# endif
+#endif
+
+#ifdef FALLOC_FL_KEEP_SIZE
+# define FL_KEEP_SIZE_FLAG FALLOC_FL_KEEP_SIZE
+# define SUPPORT_FALLOCATE
+#else
+# define FL_KEEP_SIZE_FLAG (0)
+#endif
+
+#ifdef FALLOC_FL_PUNCH_HOLE
+# define FL_PUNCH_HOLE_FLAG FALLOC_FL_PUNCH_HOLE
+#else
+# define FL_PUNCH_HOLE_FLAG (0)
+#endif
+
+#ifdef FALLOC_FL_ZERO_RANGE
+# define FL_ZERO_RANGE_FLAG FALLOC_FL_ZERO_RANGE
+#else
+# define FL_ZERO_RANGE_FLAG (0)
+#endif
+
+errcode_t ext2fs_run_ext3_journal(ext2_filsys *fs);
+
+const char *err_shortdev;
+
+#ifdef CONFIG_JBD_DEBUG		/* Enabled by configure --enable-jbd-debug */
+int journal_enable_debug = -1;
+#endif
+
+/*
+ * ext2_file_t contains a struct inode, so we can't leave files open.
+ * Use this as a proxy instead.
+ */
+#define FUSE4FS_FILE_MAGIC	(0xEF53DEAFUL)
+struct fuse4fs_file_handle {
+	unsigned long magic;
+	ext2_ino_t ino;
+	int open_flags;
+	int check_flags;
+};
+
+enum fuse4fs_opstate {
+	F4OP_READONLY,
+	F4OP_WRITABLE,
+	F4OP_SHUTDOWN,
+};
+
+/* Main program context */
+#define FUSE4FS_MAGIC		(0xEF53DEADUL)
+struct fuse4fs {
+	unsigned long magic;
+	ext2_filsys fs;
+	pthread_mutex_t bfl;
+	char *device;
+	char *shortdev;
+
+	/* options set by fuse_opt_parse must be of type int */
+	int ro;
+	int debug;
+	int no_default_opts;
+	int errors_behavior; /* actually an enum */
+	int minixdf;
+	int fakeroot;
+	int alloc_all_blocks;
+	int norecovery;
+	int kernel;
+	int directio;
+	int acl;
+	int dirsync;
+	int unmount_in_destroy;
+	int noblkdev;
+
+	enum fuse4fs_opstate opstate;
+	int logfd;
+	int blocklog;
+	unsigned int blockmask;
+	unsigned long offset;
+	unsigned int next_generation;
+	unsigned long long cache_size;
+	char *lockfile;
+#ifdef HAVE_CLOCK_MONOTONIC
+	struct timespec lock_start_time;
+	struct timespec op_start_time;
+
+	/* options set by fuse_opt_parse must be of type int */
+	int timing;
+#endif
+};
+
+#define FUSE4FS_CHECK_HANDLE(ff, fh) \
+	do { \
+		if ((fh) == NULL || (fh)->magic != FUSE4FS_FILE_MAGIC) { \
+			fprintf(stderr, \
+				"FUSE4FS: Corrupt in-memory file handle at %s:%d!\n", \
+				__func__, __LINE__); \
+			fflush(stderr); \
+			return -EUCLEAN; \
+		} \
+	} while (0)
+
+#define __FUSE4FS_CHECK_CONTEXT(ff, retcode, shutcode) \
+	do { \
+		if ((ff) == NULL || (ff)->magic != FUSE4FS_MAGIC) { \
+			fprintf(stderr, \
+				"FUSE4FS: Corrupt in-memory data at %s:%d!\n", \
+				__func__, __LINE__); \
+			fflush(stderr); \
+			retcode; \
+		} \
+		if ((ff)->opstate == F4OP_SHUTDOWN) { \
+			shutcode; \
+		} \
+	} while (0)
+
+#define FUSE4FS_CHECK_CONTEXT(ff) \
+	__FUSE4FS_CHECK_CONTEXT((ff), return -EUCLEAN, return -EIO)
+#define FUSE4FS_CHECK_CONTEXT_RETURN(ff) \
+	__FUSE4FS_CHECK_CONTEXT((ff), return, return)
+#define FUSE4FS_CHECK_CONTEXT_ABORT(ff) \
+	__FUSE4FS_CHECK_CONTEXT((ff), abort(), abort())
+
+static int __translate_error(ext2_filsys fs, ext2_ino_t ino, errcode_t err,
+			     const char *func, int line);
+#define translate_error(fs, ino, err) __translate_error((fs), (ino), (err), \
+			__func__, __LINE__)
+
+/* for macosx */
+#ifndef W_OK
+#  define W_OK 2
+#endif
+
+#ifndef R_OK
+#  define R_OK 4
+#endif
+
+static inline int u_log2(unsigned int arg)
+{
+	int	l = 0;
+
+	arg >>= 1;
+	while (arg) {
+		l++;
+		arg >>= 1;
+	}
+	return l;
+}
+
+static inline blk64_t FUSE4FS_B_TO_FSBT(const struct fuse4fs *ff, off_t pos)
+{
+	return pos >> ff->blocklog;
+}
+
+static inline blk64_t FUSE4FS_B_TO_FSB(const struct fuse4fs *ff, off_t pos)
+{
+	return (pos + ff->blockmask) >> ff->blocklog;
+}
+
+static inline unsigned int FUSE4FS_OFF_IN_FSB(const struct fuse4fs *ff,
+					      off_t pos)
+{
+	return pos & ff->blockmask;
+}
+
+static inline off_t FUSE4FS_FSB_TO_B(const struct fuse4fs *ff, blk64_t bno)
+{
+	return bno << ff->blocklog;
+}
+
+#define EXT4_EPOCH_BITS 2
+#define EXT4_EPOCH_MASK ((1 << EXT4_EPOCH_BITS) - 1)
+#define EXT4_NSEC_MASK  (~0UL << EXT4_EPOCH_BITS)
+
+/*
+ * Extended fields will fit into an inode if the filesystem was formatted
+ * with large inodes (-I 256 or larger) and there are not currently any EAs
+ * consuming all of the available space. For new inodes we always reserve
+ * enough space for the kernel's known extended fields, but for inodes
+ * created with an old kernel this might not have been the case. None of
+ * the extended inode fields is critical for correct filesystem operation.
+ * This macro checks if a certain field fits in the inode. Note that
+ * inode-size = GOOD_OLD_INODE_SIZE + i_extra_isize
+ */
+#define EXT4_FITS_IN_INODE(ext4_inode, field)		\
+	((offsetof(typeof(*ext4_inode), field) +	\
+	  sizeof((ext4_inode)->field))			\
+	 <= ((size_t) EXT2_GOOD_OLD_INODE_SIZE +		\
+	    (ext4_inode)->i_extra_isize))		\
+
+static inline __u32 ext4_encode_extra_time(const struct timespec *time)
+{
+	__u32 extra = sizeof(time->tv_sec) > 4 ?
+			((time->tv_sec - (__s32)time->tv_sec) >> 32) &
+			EXT4_EPOCH_MASK : 0;
+	return extra | (time->tv_nsec << EXT4_EPOCH_BITS);
+}
+
+static inline void ext4_decode_extra_time(struct timespec *time, __u32 extra)
+{
+	if (sizeof(time->tv_sec) > 4 && (extra & EXT4_EPOCH_MASK)) {
+		__u64 extra_bits = extra & EXT4_EPOCH_MASK;
+		/*
+		 * Prior to kernel 3.14?, we had a broken decode function,
+		 * wherein we effectively did this:
+		 * if (extra_bits == 3)
+		 *     extra_bits = 0;
+		 */
+		time->tv_sec += extra_bits << 32;
+	}
+	time->tv_nsec = ((extra) & EXT4_NSEC_MASK) >> EXT4_EPOCH_BITS;
+}
+
+#define EXT4_CLAMP_TIMESTAMP(xtime, timespec, raw_inode)		       \
+do {									       \
+	if ((timespec)->tv_sec < EXT4_TIMESTAMP_MIN)			       \
+		(timespec)->tv_sec = EXT4_TIMESTAMP_MIN;		       \
+	if ((timespec)->tv_sec < EXT4_TIMESTAMP_MIN)			       \
+		(timespec)->tv_sec = EXT4_TIMESTAMP_MIN;		       \
+									       \
+	if (EXT4_FITS_IN_INODE(raw_inode, xtime ## _extra)) {		       \
+		if ((timespec)->tv_sec > EXT4_EXTRA_TIMESTAMP_MAX)	       \
+			(timespec)->tv_sec = EXT4_EXTRA_TIMESTAMP_MAX;	       \
+	} else {							       \
+		if ((timespec)->tv_sec > EXT4_NON_EXTRA_TIMESTAMP_MAX)	       \
+			(timespec)->tv_sec = EXT4_NON_EXTRA_TIMESTAMP_MAX;     \
+	}								       \
+} while (0)
+
+#define EXT4_INODE_SET_XTIME(xtime, timespec, raw_inode)		       \
+do {									       \
+	typeof(*(timespec)) _ts = *(timespec);				       \
+									       \
+	EXT4_CLAMP_TIMESTAMP(xtime, &_ts, raw_inode);			       \
+	(raw_inode)->xtime = _ts.tv_sec;				       \
+	if (EXT4_FITS_IN_INODE(raw_inode, xtime ## _extra))		       \
+		(raw_inode)->xtime ## _extra =				       \
+				ext4_encode_extra_time(&_ts);		       \
+} while (0)
+
+#define EXT4_EINODE_SET_XTIME(xtime, timespec, raw_inode)		       \
+do {									       \
+	typeof(*(timespec)) _ts = *(timespec);				       \
+									       \
+	EXT4_CLAMP_TIMESTAMP(xtime, &_ts, raw_inode);			       \
+	if (EXT4_FITS_IN_INODE(raw_inode, xtime))			       \
+		(raw_inode)->xtime = _ts.tv_sec;			       \
+	if (EXT4_FITS_IN_INODE(raw_inode, xtime ## _extra))		       \
+		(raw_inode)->xtime ## _extra =				       \
+				ext4_encode_extra_time(&_ts);		       \
+} while (0)
+
+#define EXT4_INODE_GET_XTIME(xtime, timespec, raw_inode)		       \
+do {									       \
+	(timespec)->tv_sec = (signed)((raw_inode)->xtime);		       \
+	if (EXT4_FITS_IN_INODE(raw_inode, xtime ## _extra))		       \
+		ext4_decode_extra_time((timespec),			       \
+				       (raw_inode)->xtime ## _extra);	       \
+	else								       \
+		(timespec)->tv_nsec = 0;				       \
+} while (0)
+
+#define EXT4_EINODE_GET_XTIME(xtime, timespec, raw_inode)		       \
+do {									       \
+	if (EXT4_FITS_IN_INODE(raw_inode, xtime))			       \
+		(timespec)->tv_sec =					       \
+			(signed)((raw_inode)->xtime);			       \
+	if (EXT4_FITS_IN_INODE(raw_inode, xtime ## _extra))		       \
+		ext4_decode_extra_time((timespec),			       \
+				       raw_inode->xtime ## _extra);	       \
+	else								       \
+		(timespec)->tv_nsec = 0;				       \
+} while (0)
+
+static inline errcode_t fuse4fs_read_inode(ext2_filsys fs, ext2_ino_t ino,
+					   struct ext2_inode_large *inode)
+{
+	memset(inode, 0, sizeof(*inode));
+	return ext2fs_read_inode_full(fs, ino, EXT2_INODE(inode),
+				      sizeof(*inode));
+}
+
+static inline errcode_t fuse4fs_write_inode(ext2_filsys fs, ext2_ino_t ino,
+					    struct ext2_inode_large *inode)
+{
+	return ext2fs_write_inode_full(fs, ino, EXT2_INODE(inode),
+				       sizeof(*inode));
+}
+
+static inline struct fuse4fs *fuse4fs_get(void)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+
+	return ctxt->private_data;
+}
+
+static inline struct fuse4fs_file_handle *
+fuse4fs_get_handle(const struct fuse_file_info *fp)
+{
+	return (struct fuse4fs_file_handle *)(uintptr_t)fp->fh;
+}
+
+static inline void
+fuse4fs_set_handle(struct fuse_file_info *fp, struct fuse4fs_file_handle *fh)
+{
+	fp->fh = (uintptr_t)fh;
+}
+
+#ifdef HAVE_CLOCK_MONOTONIC
+static inline ext2_filsys fuse4fs_start(struct fuse4fs *ff)
+{
+	struct timespec lock_time;
+	int ret;
+
+	if (ff->timing)
+		clock_gettime(CLOCK_MONOTONIC, &lock_time);
+
+	pthread_mutex_lock(&ff->bfl);
+	if (ff->timing) {
+		ret = clock_gettime(CLOCK_MONOTONIC, &ff->op_start_time);
+		if (ret)
+			ff->timing = 0;
+		ff->lock_start_time = lock_time;
+	}
+	return ff->fs;
+}
+
+static inline double ms_from_timespec(const struct timespec *ts)
+{
+	return ((double)ts->tv_sec * 1000) + ((double)ts->tv_nsec / 1000000);
+}
+
+static inline void fuse4fs_finish_timing(struct fuse4fs *ff, const char *func)
+{
+	struct timespec now;
+	double lockf, startf, nowf;
+	int ret;
+
+	if (!ff->timing)
+		return;
+
+	ret = clock_gettime(CLOCK_MONOTONIC, &now);
+	if (ret) {
+		ff->timing = 0;
+		return;
+	}
+
+	lockf = ms_from_timespec(&ff->lock_start_time);
+	startf = ms_from_timespec(&ff->op_start_time);
+	nowf = ms_from_timespec(&now);
+	timing_printf(ff, "%s: lock=%.2fms elapsed=%.2fms\n", func,
+		      startf - lockf, nowf - startf);
+}
+#else
+static inline ext2_filsys fuse4fs_start(struct fuse4fs *ff)
+{
+	pthread_mutex_lock(&ff->bfl);
+	return ff->fs;
+}
+# define fuse4fs_finish_timing(...)	((void)0)
+#endif
+
+static inline void __fuse4fs_finish(struct fuse4fs *ff, int ret,
+				    const char *func)
+{
+	fuse4fs_finish_timing(ff, func);
+	if (ret)
+		dbg_printf(ff, "%s: libfuse ret=%d\n", func, ret);
+	pthread_mutex_unlock(&ff->bfl);
+}
+#define fuse4fs_finish(ff, ret) __fuse4fs_finish((ff), (ret), __func__)
+
+static void get_now(struct timespec *now)
+{
+#ifdef CLOCK_REALTIME
+	if (!clock_gettime(CLOCK_REALTIME, now))
+		return;
+#endif
+
+	now->tv_sec = time(NULL);
+	now->tv_nsec = 0;
+}
+
+static void increment_version(struct ext2_inode_large *inode)
+{
+	__u64 ver;
+
+	ver = inode->osd1.linux1.l_i_version;
+	if (EXT4_FITS_IN_INODE(inode, i_version_hi))
+		ver |= (__u64)inode->i_version_hi << 32;
+	ver++;
+	inode->osd1.linux1.l_i_version = ver;
+	if (EXT4_FITS_IN_INODE(inode, i_version_hi))
+		inode->i_version_hi = ver >> 32;
+}
+
+static void init_times(struct ext2_inode_large *inode)
+{
+	struct timespec now;
+
+	get_now(&now);
+	EXT4_INODE_SET_XTIME(i_atime, &now, inode);
+	EXT4_INODE_SET_XTIME(i_ctime, &now, inode);
+	EXT4_INODE_SET_XTIME(i_mtime, &now, inode);
+	EXT4_EINODE_SET_XTIME(i_crtime, &now, inode);
+	increment_version(inode);
+}
+
+static int update_ctime(ext2_filsys fs, ext2_ino_t ino,
+			struct ext2_inode_large *pinode)
+{
+	errcode_t err;
+	struct timespec now;
+	struct ext2_inode_large inode;
+
+	get_now(&now);
+
+	/* If user already has a inode buffer, just update that */
+	if (pinode) {
+		increment_version(pinode);
+		EXT4_INODE_SET_XTIME(i_ctime, &now, pinode);
+		return 0;
+	}
+
+	/* Otherwise we have to read-modify-write the inode */
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	increment_version(&inode);
+	EXT4_INODE_SET_XTIME(i_ctime, &now, &inode);
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
+static int update_atime(ext2_filsys fs, ext2_ino_t ino)
+{
+	errcode_t err;
+	struct ext2_inode_large inode, *pinode;
+	struct timespec atime, mtime, now;
+	double datime, dmtime, dnow;
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	pinode = &inode;
+	EXT4_INODE_GET_XTIME(i_atime, &atime, pinode);
+	EXT4_INODE_GET_XTIME(i_mtime, &mtime, pinode);
+	get_now(&now);
+
+	datime = atime.tv_sec + ((double)atime.tv_nsec / 1000000000);
+	dmtime = mtime.tv_sec + ((double)mtime.tv_nsec / 1000000000);
+	dnow = now.tv_sec + ((double)now.tv_nsec / 1000000000);
+
+	/*
+	 * If atime is newer than mtime and atime hasn't been updated in thirty
+	 * seconds, skip the atime update.  Same idea as Linux "relatime".  Use
+	 * doubles to account for nanosecond resolution.
+	 */
+	if (datime >= dmtime && datime >= dnow - 30)
+		return 0;
+	EXT4_INODE_SET_XTIME(i_atime, &now, &inode);
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
+static int update_mtime(ext2_filsys fs, ext2_ino_t ino,
+			struct ext2_inode_large *pinode)
+{
+	errcode_t err;
+	struct ext2_inode_large inode;
+	struct timespec now;
+
+	if (pinode) {
+		get_now(&now);
+		EXT4_INODE_SET_XTIME(i_mtime, &now, pinode);
+		EXT4_INODE_SET_XTIME(i_ctime, &now, pinode);
+		increment_version(pinode);
+		return 0;
+	}
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	get_now(&now);
+	EXT4_INODE_SET_XTIME(i_mtime, &now, &inode);
+	EXT4_INODE_SET_XTIME(i_ctime, &now, &inode);
+	increment_version(&inode);
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
+static int ext2_file_type(unsigned int mode)
+{
+	if (LINUX_S_ISREG(mode))
+		return EXT2_FT_REG_FILE;
+
+	if (LINUX_S_ISDIR(mode))
+		return EXT2_FT_DIR;
+
+	if (LINUX_S_ISCHR(mode))
+		return EXT2_FT_CHRDEV;
+
+	if (LINUX_S_ISBLK(mode))
+		return EXT2_FT_BLKDEV;
+
+	if (LINUX_S_ISLNK(mode))
+		return EXT2_FT_SYMLINK;
+
+	if (LINUX_S_ISFIFO(mode))
+		return EXT2_FT_FIFO;
+
+	if (LINUX_S_ISSOCK(mode))
+		return EXT2_FT_SOCK;
+
+	return 0;
+}
+
+static int fs_can_allocate(struct fuse4fs *ff, blk64_t num)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t reserved;
+
+	dbg_printf(ff, "%s: Asking for %llu; alloc_all=%d total=%llu free=%llu "
+		   "rsvd=%llu\n", __func__, num, ff->alloc_all_blocks,
+		   ext2fs_blocks_count(fs->super),
+		   ext2fs_free_blocks_count(fs->super),
+		   ext2fs_r_blocks_count(fs->super));
+	if (num > ext2fs_blocks_count(fs->super))
+		return 0;
+
+	if (ff->alloc_all_blocks)
+		return 1;
+
+	/*
+	 * Different meaning for r_blocks -- libext2fs has bugs where the FS
+	 * can get corrupted if it totally runs out of blocks.  Avoid this
+	 * by refusing to allocate any of the reserve blocks to anybody.
+	 */
+	reserved = ext2fs_r_blocks_count(fs->super);
+	if (reserved == 0)
+		reserved = ext2fs_blocks_count(fs->super) / 10;
+	return ext2fs_free_blocks_count(fs->super) > reserved + num;
+}
+
+static int fuse4fs_is_writeable(struct fuse4fs *ff)
+{
+	return ff->opstate == F4OP_WRITABLE &&
+		(ff->fs->super->s_error_count == 0);
+}
+
+static inline int is_superuser(struct fuse4fs *ff, struct fuse_context *ctxt)
+{
+	if (ff->fakeroot)
+		return 1;
+	return ctxt->uid == 0;
+}
+
+static inline int want_check_owner(struct fuse4fs *ff,
+				   struct fuse_context *ctxt)
+{
+	/*
+	 * The kernel is responsible for access control, so we allow anything
+	 * that the superuser can do.
+	 */
+	if (ff->kernel)
+		return 0;
+	return !is_superuser(ff, ctxt);
+}
+
+/* Test for append permission */
+#define A_OK	16
+
+static int check_iflags_access(struct fuse4fs *ff, ext2_ino_t ino,
+			       const struct ext2_inode *inode, int mask)
+{
+	EXT2FS_BUILD_BUG_ON((A_OK & (R_OK | W_OK | X_OK | F_OK)) != 0);
+
+	/* no writing or metadata changes to read-only or broken fs */
+	if ((mask & (W_OK | A_OK)) && !fuse4fs_is_writeable(ff))
+		return -EROFS;
+
+	dbg_printf(ff, "access ino=%d mask=e%s%s%s%s iflags=0x%x\n",
+		   ino,
+		   (mask & R_OK ? "r" : ""),
+		   (mask & W_OK ? "w" : ""),
+		   (mask & X_OK ? "x" : ""),
+		   (mask & A_OK ? "a" : ""),
+		   inode->i_flags);
+
+	/* is immutable? */
+	if ((mask & W_OK) &&
+	    (inode->i_flags & EXT2_IMMUTABLE_FL))
+		return -EPERM;
+
+	/* is append-only? */
+	if ((inode->i_flags & EXT2_APPEND_FL) && (mask & W_OK) && !(mask & A_OK))
+		return -EPERM;
+
+	return 0;
+}
+
+static int check_inum_access(struct fuse4fs *ff, ext2_ino_t ino, int mask)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	ext2_filsys fs = ff->fs;
+	struct ext2_inode inode;
+	mode_t perms;
+	errcode_t err;
+	int ret;
+
+	/* no writing to read-only or broken fs */
+	if ((mask & (W_OK | A_OK)) && !fuse4fs_is_writeable(ff))
+		return -EROFS;
+
+	err = ext2fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+	perms = inode.i_mode & 0777;
+
+	dbg_printf(ff, "access ino=%d mask=e%s%s%s%s perms=0%o iflags=0x%x "
+		   "fuid=%d fgid=%d uid=%d gid=%d\n", ino,
+		   (mask & R_OK ? "r" : ""),
+		   (mask & W_OK ? "w" : ""),
+		   (mask & X_OK ? "x" : ""),
+		   (mask & A_OK ? "a" : ""),
+		   perms, inode.i_flags,
+		   inode_uid(inode), inode_gid(inode),
+		   ctxt->uid, ctxt->gid);
+
+	/* existence check */
+	if (mask == 0)
+		return 0;
+
+	ret = check_iflags_access(ff, ino, &inode, mask);
+	if (ret)
+		return ret;
+
+	/* If kernel is responsible for mode and acl checks, we're done. */
+	if (ff->kernel)
+		return 0;
+
+	/* Figure out what root's allowed to do */
+	if (is_superuser(ff, ctxt)) {
+		/* Non-file access always ok */
+		if (!LINUX_S_ISREG(inode.i_mode))
+			return 0;
+
+		/* R/W access to a file always ok */
+		if (!(mask & X_OK))
+			return 0;
+
+		/* X access to a file ok if a user/group/other can X */
+		if (perms & 0111)
+			return 0;
+
+		/* Trying to execute a file that's not executable. BZZT! */
+		return -EACCES;
+	}
+
+	/* Remove the O_APPEND flag before testing permissions */
+	mask &= ~A_OK;
+
+	/* allow owner, if perms match */
+	if (inode_uid(inode) == ctxt->uid) {
+		if ((mask & (perms >> 6)) == mask)
+			return 0;
+		return -EACCES;
+	}
+
+	/* allow group, if perms match */
+	if (inode_gid(inode) == ctxt->gid) {
+		if ((mask & (perms >> 3)) == mask)
+			return 0;
+		return -EACCES;
+	}
+
+	/* otherwise check other */
+	if ((mask & perms) == mask)
+		return 0;
+	return -EACCES;
+}
+
+static errcode_t fuse4fs_acquire_lockfile(struct fuse4fs *ff)
+{
+	char *resolved;
+	int lockfd;
+	errcode_t err;
+
+	lockfd = open(ff->lockfile, O_RDWR | O_CREAT | O_EXCL, 0400);
+	if (lockfd < 0) {
+		if (errno == EEXIST)
+			err = EWOULDBLOCK;
+		else
+			err = errno;
+		err_printf(ff, "%s: %s: %s\n", ff->lockfile,
+			   _("opening lockfile failed"),
+			   strerror(err));
+		ff->lockfile = NULL;
+		return err;
+	}
+	close(lockfd);
+
+	resolved = realpath(ff->lockfile, NULL);
+	if (!resolved) {
+		err = errno;
+		err_printf(ff, "%s: %s: %s\n", ff->lockfile,
+			   _("resolving lockfile failed"),
+			   strerror(err));
+		unlink(ff->lockfile);
+		ff->lockfile = NULL;
+		return err;
+	}
+	free(ff->lockfile);
+	ff->lockfile = resolved;
+
+	return 0;
+}
+
+static void fuse4fs_release_lockfile(struct fuse4fs *ff)
+{
+	if (unlink(ff->lockfile)) {
+		errcode_t err = errno;
+
+		err_printf(ff, "%s: %s: %s\n", ff->lockfile,
+			   _("removing lockfile failed"),
+			   strerror(err));
+	}
+	free(ff->lockfile);
+}
+
+static void fuse4fs_unmount(struct fuse4fs *ff)
+{
+	errcode_t err;
+
+	if (!ff->fs)
+		return;
+
+	err = ext2fs_close(ff->fs);
+	if (err) {
+		err_printf(ff, "%s: %s\n", _("while closing fs"),
+			   error_message(err));
+		ext2fs_free(ff->fs);
+	}
+	ff->fs = NULL;
+
+	if (ff->lockfile)
+		fuse4fs_release_lockfile(ff);
+}
+
+static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
+{
+	char options[128];
+	int flags = EXT2_FLAG_64BITS | EXT2_FLAG_THREADS | EXT2_FLAG_RW |
+		    libext2_flags;
+	errcode_t err;
+
+	if (ff->lockfile) {
+		err = fuse4fs_acquire_lockfile(ff);
+		if (err)
+			return err;
+	}
+
+	snprintf(options, sizeof(options) - 1, "offset=%lu", ff->offset);
+	ff->opstate = F4OP_READONLY;
+
+	if (ff->directio)
+		flags |= EXT2_FLAG_DIRECT_IO;
+
+	err = ext2fs_open2(ff->device, options, flags, 0, 0, unix_io_manager,
+			   &ff->fs);
+	if (err == EPERM) {
+		err_printf(ff, "%s.\n",
+			   _("read-only device, trying to mount norecovery"));
+		flags &= ~EXT2_FLAG_RW;
+		ff->ro = 1;
+		ff->norecovery = 1;
+		err = ext2fs_open2(ff->device, options, flags, 0, 0,
+				   unix_io_manager, &ff->fs);
+	}
+	if (err) {
+		err_printf(ff, "%s.\n", error_message(err));
+		err_printf(ff, "%s\n", _("Please run e2fsck -fy."));
+		return err;
+	}
+
+	ff->fs->priv_data = ff;
+	ff->blocklog = u_log2(ff->fs->blocksize);
+	ff->blockmask = ff->fs->blocksize - 1;
+	return 0;
+}
+
+static inline bool fuse4fs_on_bdev(const struct fuse4fs *ff)
+{
+	return ff->fs->io->flags & CHANNEL_FLAGS_BLOCK_DEVICE;
+}
+
+static errcode_t fuse4fs_config_cache(struct fuse4fs *ff)
+{
+	char buf[128];
+	errcode_t err;
+
+	snprintf(buf, sizeof(buf), "cache_blocks=%llu",
+		 FUSE4FS_B_TO_FSBT(ff, ff->cache_size));
+	err = io_channel_set_options(ff->fs->io, buf);
+	if (err) {
+		err_printf(ff, "%s %lluk: %s\n",
+			   _("cannot set disk cache size to"),
+			   ff->cache_size >> 10,
+			   error_message(err));
+		return err;
+	}
+
+	return 0;
+}
+
+static errcode_t fuse4fs_check_support(struct fuse4fs *ff)
+{
+	ext2_filsys fs = ff->fs;
+
+	if (ext2fs_has_feature_quota(fs->super)) {
+		err_printf(ff, "%s\n", _("quotas not supported."));
+		return EXT2_ET_UNSUPP_FEATURE;
+	}
+	if (ext2fs_has_feature_verity(fs->super)) {
+		err_printf(ff, "%s\n", _("verity not supported."));
+		return EXT2_ET_UNSUPP_FEATURE;
+	}
+	if (ext2fs_has_feature_encrypt(fs->super)) {
+		err_printf(ff, "%s\n", _("encryption not supported."));
+		return EXT2_ET_UNSUPP_FEATURE;
+	}
+	if (ext2fs_has_feature_casefold(fs->super)) {
+		err_printf(ff, "%s\n", _("casefolding not supported."));
+		return EXT2_ET_UNSUPP_FEATURE;
+	}
+
+	if (fs->super->s_state & EXT2_ERROR_FS) {
+		err_printf(ff, "%s\n",
+ _("Errors detected; running e2fsck is required."));
+		return EXT2_ET_FILESYSTEM_CORRUPTED;
+	}
+
+	return 0;
+}
+
+static int fuse4fs_check_norecovery(struct fuse4fs *ff)
+{
+	if (ext2fs_has_feature_journal_needs_recovery(ff->fs->super) &&
+	    !ff->ro) {
+		log_printf(ff, "%s\n",
+ _("Required journal recovery suppressed and not mounted read-only."));
+		return 32;
+	}
+
+	/*
+	 * Amazingly, norecovery allows a rw mount when there's a clean journal
+	 * present.
+	 */
+	return 0;
+}
+
+static int fuse4fs_mount(struct fuse4fs *ff)
+{
+	struct ext2_inode_large inode;
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+
+	if (ext2fs_has_feature_journal_needs_recovery(fs->super)) {
+		if (ff->norecovery) {
+			log_printf(ff, "%s\n",
+ _("Mounting read-only without recovering journal."));
+		} else {
+			log_printf(ff, "%s\n", _("Recovering journal."));
+			err = ext2fs_run_ext3_journal(&ff->fs);
+			if (err) {
+				err_printf(ff, "%s.\n", error_message(err));
+				err_printf(ff, "%s\n",
+						_("Please run e2fsck -fy."));
+				return translate_error(fs, 0, err);
+			}
+			fs = ff->fs;
+			ext2fs_clear_feature_journal_needs_recovery(fs->super);
+			ext2fs_mark_super_dirty(fs);
+
+			err = fuse4fs_check_support(ff);
+			if (err)
+				return err;
+		}
+	}
+
+	/* Make sure the root directory is readable. */
+	err = fuse4fs_read_inode(fs, EXT2_ROOT_INO, &inode);
+	if (err)
+		return translate_error(fs, EXT2_ROOT_INO, err);
+
+	if (fs->flags & EXT2_FLAG_RW) {
+		if (ext2fs_has_feature_journal(fs->super))
+			log_printf(ff, "%s",
+ _("Warning: fuse4fs does not support using the journal.\n"
+   "There may be file system corruption or data loss if\n"
+   "the file system is not gracefully unmounted.\n"));
+		ff->opstate = F4OP_WRITABLE;
+	}
+
+	if (!(fs->super->s_state & EXT2_VALID_FS))
+		err_printf(ff, "%s\n",
+ _("Warning: Mounting unchecked fs, running e2fsck is recommended."));
+	if (fs->super->s_max_mnt_count > 0 &&
+	    fs->super->s_mnt_count >= fs->super->s_max_mnt_count)
+		err_printf(ff, "%s\n",
+ _("Warning: Maximal mount count reached, running e2fsck is recommended."));
+	if (fs->super->s_checkinterval > 0 &&
+	    (time_t) (fs->super->s_lastcheck +
+		      fs->super->s_checkinterval) <= time(0))
+		err_printf(ff, "%s\n",
+ _("Warning: Check time reached; running e2fsck is recommended."));
+	if (fs->super->s_last_orphan)
+		err_printf(ff, "%s\n",
+ _("Orphans detected; running e2fsck is recommended."));
+
+	if (!ff->errors_behavior)
+		ff->errors_behavior = fs->super->s_errors;
+
+	/* Clear the valid flag so that an unclean shutdown forces a fsck */
+	if (ff->opstate == F4OP_WRITABLE) {
+		fs->super->s_mnt_count++;
+		ext2fs_set_tstamp(fs->super, s_mtime, time(NULL));
+		fs->super->s_state &= ~EXT2_VALID_FS;
+		ext2fs_mark_super_dirty(fs);
+		err = ext2fs_flush2(fs, 0);
+		if (err)
+			return translate_error(fs, 0, err);
+	}
+
+	return 0;
+}
+
+static void op_destroy(void *p EXT2FS_ATTR((unused)))
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	errcode_t err;
+
+	FUSE4FS_CHECK_CONTEXT_RETURN(ff);
+
+	fs = fuse4fs_start(ff);
+
+	dbg_printf(ff, "%s: dev=%s\n", __func__, fs->device_name);
+	if (ff->opstate == F4OP_WRITABLE) {
+		fs->super->s_state |= EXT2_VALID_FS;
+		if (fs->super->s_error_count)
+			fs->super->s_state |= EXT2_ERROR_FS;
+		ext2fs_mark_super_dirty(fs);
+		err = ext2fs_set_gdt_csum(fs);
+		if (err)
+			translate_error(fs, 0, err);
+
+		err = ext2fs_flush2(fs, 0);
+		if (err)
+			translate_error(fs, 0, err);
+	}
+
+	if (ff->debug && fs->io->manager->get_stats) {
+		io_stats stats = NULL;
+
+		fs->io->manager->get_stats(fs->io, &stats);
+		dbg_printf(ff, "read: %lluk\n",  stats->bytes_read >> 10);
+		dbg_printf(ff, "write: %lluk\n", stats->bytes_written >> 10);
+		dbg_printf(ff, "hits: %llu\n",   stats->cache_hits);
+		dbg_printf(ff, "misses: %llu\n", stats->cache_misses);
+		dbg_printf(ff, "hit_ratio: %.1f%%\n",
+				(100.0 * stats->cache_hits) /
+				(stats->cache_hits + stats->cache_misses));
+	}
+
+	if (ff->kernel) {
+		char uuid[UUID_STR_SIZE];
+
+		uuid_unparse(fs->super->s_uuid, uuid);
+		log_printf(ff, "%s %s.\n", _("unmounting filesystem"), uuid);
+	}
+
+	if (ff->unmount_in_destroy)
+		fuse4fs_unmount(ff);
+
+	fuse4fs_finish(ff, 0);
+}
+
+/* Reopen @stream with @fileno */
+static int fuse4fs_freopen_stream(const char *path, int fileno, FILE *stream)
+{
+	char _fdpath[256];
+	const char *fdpath;
+	FILE *fp;
+	int ret;
+
+	ret = snprintf(_fdpath, sizeof(_fdpath), "/dev/fd/%d", fileno);
+	if (ret >= sizeof(_fdpath))
+		fdpath = path;
+	else
+		fdpath = _fdpath;
+
+	/*
+	 * C23 defines std{out,err} as an expression of type FILE* that need
+	 * not be an lvalue.  What this means is that we can't just assign to
+	 * stdout: we have to use freopen, which takes a path.
+	 *
+	 * There's no guarantee that the OS provides a /dev/fd/X alias for open
+	 * file descriptors, so if that fails, fall back to the original log
+	 * file path.  We'd rather not do a path-based reopen because that
+	 * exposes us to rename race attacks.
+	 */
+	fp = freopen(fdpath, "a", stream);
+	if (!fp && errno == ENOENT && fdpath == _fdpath)
+		fp = freopen(path, "a", stream);
+	if (!fp) {
+		perror(fdpath);
+		return -1;
+	}
+
+	return 0;
+}
+
+/* Redirect stdout/stderr to a file, or return a mount-compatible error. */
+static int fuse4fs_capture_output(struct fuse4fs *ff, const char *path)
+{
+	int ret;
+	int fd;
+
+	/*
+	 * First, open the log file path with system calls so that we can
+	 * redirect the stdout/stderr file numbers (typically 1 and 2) to our
+	 * logfile descriptor.  We'd like to avoid allocating extra file
+	 * objects in the kernel if we can because pos will be the same between
+	 * stdout and stderr.
+	 */
+	if (ff->logfd < 0) {
+		fd = open(path, O_WRONLY | O_CREAT | O_APPEND, 0600);
+		if (fd < 0) {
+			perror(path);
+			return -1;
+		}
+
+		/*
+		 * Save the newly opened fd in case we have to do this again in
+		 * op_init.
+		 */
+		ff->logfd = fd;
+	}
+
+	ret = dup2(ff->logfd, STDOUT_FILENO);
+	if (ret < 0) {
+		perror(path);
+		return -1;
+	}
+
+	ret = dup2(ff->logfd, STDERR_FILENO);
+	if (ret < 0) {
+		perror(path);
+		return -1;
+	}
+
+	/*
+	 * Now that we've changed STD{OUT,ERR}_FILENO to be the log file, use
+	 * freopen to make sure that std{out,err} (the C library abstractions)
+	 * point to the STDXXX_FILENO because any of our library dependencies
+	 * might decide to printf to one of those streams and we want to
+	 * capture all output in the log.
+	 */
+	ret = fuse4fs_freopen_stream(path, STDOUT_FILENO, stdout);
+	if (ret)
+		return ret;
+	ret = fuse4fs_freopen_stream(path, STDERR_FILENO, stderr);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+/* Set up debug and error logging files */
+static int fuse4fs_setup_logging(struct fuse4fs *ff)
+{
+	char *logfile = getenv("FUSE4FS_LOGFILE");
+	if (logfile)
+		return fuse4fs_capture_output(ff, logfile);
+
+	/* in kernel mode, try to log errors to the kernel log */
+	if (ff->kernel)
+		fuse4fs_capture_output(ff, "/dev/ttyprintk");
+
+	return 0;
+}
+
+static int fuse4fs_read_bitmaps(struct fuse4fs *ff)
+{
+	errcode_t err;
+
+	err = ext2fs_read_inode_bitmap(ff->fs);
+	if (err)
+		return translate_error(ff->fs, 0, err);
+
+	err = ext2fs_read_block_bitmap(ff->fs);
+	if (err)
+		return translate_error(ff->fs, 0, err);
+
+	return 0;
+}
+
+#if FUSE_VERSION < FUSE_MAKE_VERSION(3, 17)
+static inline int fuse_set_feature_flag(struct fuse_conn_info *conn,
+					 uint64_t flag)
+{
+	if (conn->capable & flag) {
+		conn->want |= flag;
+		return 1;
+	}
+
+	return 0;
+}
+#endif
+
+static void *op_init(struct fuse_conn_info *conn,
+		     struct fuse_config *cfg EXT2FS_ATTR((unused)))
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+
+	FUSE4FS_CHECK_CONTEXT_ABORT(ff);
+
+	/*
+	 * Configure logging a second time, because libfuse might have
+	 * redirected std{out,err} as part of daemonization.  If this fails,
+	 * give up and move on.
+	 */
+	fuse4fs_setup_logging(ff);
+	if (ff->logfd >= 0)
+		close(ff->logfd);
+	ff->logfd = -1;
+
+	fs = ff->fs;
+	dbg_printf(ff, "%s: dev=%s\n", __func__, fs->device_name);
+#ifdef FUSE_CAP_IOCTL_DIR
+	fuse_set_feature_flag(conn, FUSE_CAP_IOCTL_DIR);
+#endif
+#ifdef FUSE_CAP_POSIX_ACL
+	if (ff->acl)
+		fuse_set_feature_flag(conn, FUSE_CAP_POSIX_ACL);
+#endif
+#ifdef FUSE_CAP_CACHE_SYMLINKS
+	fuse_set_feature_flag(conn, FUSE_CAP_CACHE_SYMLINKS);
+#endif
+#ifdef FUSE_CAP_NO_EXPORT_SUPPORT
+	fuse_set_feature_flag(conn, FUSE_CAP_NO_EXPORT_SUPPORT);
+#endif
+	conn->time_gran = 1;
+	cfg->use_ino = 1;
+	if (ff->debug)
+		cfg->debug = 1;
+	cfg->nullpath_ok = 1;
+
+	if (ff->kernel) {
+		char uuid[UUID_STR_SIZE];
+
+		uuid_unparse(fs->super->s_uuid, uuid);
+		log_printf(ff, "%s %s.\n", _("mounted filesystem"), uuid);
+	}
+
+	if (ff->opstate == F4OP_WRITABLE)
+		fuse4fs_read_bitmaps(ff);
+
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 17)
+	/*
+	 * THIS MUST GO LAST!
+	 *
+	 * fuse_set_feature_flag in 3.17.0 has a strange bug: it sets feature
+	 * flags in conn->want_ext, but not conn->want.  Upon return to
+	 * libfuse, the lower level library observes that want and want_ext
+	 * have gotten out of sync, and refuses to mount.  Therefore,
+	 * synchronize the two.  This bug went away in 3.17.3, but we're stuck
+	 * with this forever because Debian trixie released with 3.17.2.
+	 */
+	conn->want = conn->want_ext & 0xFFFFFFFF;
+#endif
+	return ff;
+}
+
+static int stat_inode(ext2_filsys fs, ext2_ino_t ino, struct stat *statbuf)
+{
+	struct ext2_inode_large inode;
+	dev_t fakedev = 0;
+	errcode_t err;
+	int ret = 0;
+	struct timespec tv;
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	memcpy(&fakedev, fs->super->s_uuid, sizeof(fakedev));
+	statbuf->st_dev = fakedev;
+	statbuf->st_ino = ino;
+	statbuf->st_mode = inode.i_mode;
+	statbuf->st_nlink = inode.i_links_count;
+	statbuf->st_uid = inode_uid(inode);
+	statbuf->st_gid = inode_gid(inode);
+	statbuf->st_size = EXT2_I_SIZE(&inode);
+	statbuf->st_blksize = fs->blocksize;
+	statbuf->st_blocks = ext2fs_get_stat_i_blocks(fs,
+						EXT2_INODE(&inode));
+	EXT4_INODE_GET_XTIME(i_atime, &tv, &inode);
+#if HAVE_STRUCT_STAT_ST_ATIM
+	statbuf->st_atim = tv;
+#else
+	statbuf->st_atime = tv.tv_sec;
+#endif
+	EXT4_INODE_GET_XTIME(i_mtime, &tv, &inode);
+#if HAVE_STRUCT_STAT_ST_ATIM
+	statbuf->st_mtim = tv;
+#else
+	statbuf->st_mtime = tv.tv_sec;
+#endif
+	EXT4_INODE_GET_XTIME(i_ctime, &tv, &inode);
+#if HAVE_STRUCT_STAT_ST_ATIM
+	statbuf->st_ctim = tv;
+#else
+	statbuf->st_ctime = tv.tv_sec;
+#endif
+	if (LINUX_S_ISCHR(inode.i_mode) ||
+	    LINUX_S_ISBLK(inode.i_mode)) {
+		if (inode.i_block[0])
+			statbuf->st_rdev = inode.i_block[0];
+		else
+			statbuf->st_rdev = inode.i_block[1];
+	}
+
+	return ret;
+}
+
+static int __fuse4fs_file_ino(struct fuse4fs *ff, const char *path,
+			      struct fuse_file_info *fp EXT2FS_ATTR((unused)),
+			      ext2_ino_t *inop,
+			      const char *func,
+			      int line)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+
+	if (fp) {
+		struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+
+		if (fh->ino == 0)
+			return -ESTALE;
+
+		*inop = fh->ino;
+		dbg_printf(ff, "%s: get ino=%d\n", func, fh->ino);
+		return 0;
+	}
+
+	dbg_printf(ff, "%s: get path=%s\n", func, path);
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, inop);
+	if (err)
+		return __translate_error(fs, 0, err, func, line);
+
+	return 0;
+}
+
+# define fuse4fs_file_ino(ff, path, fp, inop) \
+	__fuse4fs_file_ino((ff), (path), (fp), (inop), __func__, __LINE__)
+
+static int op_getattr(const char *path, struct stat *statbuf,
+		      struct fuse_file_info *fi)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	ext2_ino_t ino;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	ret = fuse4fs_file_ino(ff, path, fi, &ino);
+	if (ret)
+		goto out;
+	ret = stat_inode(fs, ino, statbuf);
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int op_readlink(const char *path, char *buf, size_t len)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	errcode_t err;
+	ext2_ino_t ino;
+	struct ext2_inode inode;
+	unsigned int got;
+	ext2_file_t file;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: path=%s\n", __func__, path);
+	fs = fuse4fs_start(ff);
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	if (err || ino == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+
+	err = ext2fs_read_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+	if (!LINUX_S_ISLNK(inode.i_mode)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	len--;
+	if (inode.i_size < len)
+		len = inode.i_size;
+	if (ext2fs_is_fast_symlink(&inode))
+		memcpy(buf, (char *)inode.i_block, len);
+	else {
+		/* big/inline symlink */
+
+		err = ext2fs_file_open(fs, ino, 0, &file);
+		if (err) {
+			ret = translate_error(fs, ino, err);
+			goto out;
+		}
+
+		err = ext2fs_file_read(file, buf, len, &got);
+		if (err)
+			ret = translate_error(fs, ino, err);
+		else if (got != len)
+			ret = translate_error(fs, ino, EXT2_ET_INODE_CORRUPTED);
+
+		err = ext2fs_file_close(file);
+		if (ret)
+			goto out;
+		if (err) {
+			ret = translate_error(fs, ino, err);
+			goto out;
+		}
+	}
+	buf[len] = 0;
+
+	if (fuse4fs_is_writeable(ff)) {
+		ret = update_atime(fs, ino);
+		if (ret)
+			goto out;
+	}
+
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int __getxattr(struct fuse4fs *ff, ext2_ino_t ino, const char *name,
+		      void **value, size_t *value_len)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_xattr_handle *h;
+	errcode_t err;
+	int ret = 0;
+
+	err = ext2fs_xattrs_open(fs, ino, &h);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_xattrs_read(h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_close;
+	}
+
+	err = ext2fs_xattr_get(h, name, value, value_len);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_close;
+	}
+
+out_close:
+	err = ext2fs_xattrs_close(&h);
+	if (err && !ret)
+		ret = translate_error(fs, ino, err);
+	return ret;
+}
+
+static int __setxattr(struct fuse4fs *ff, ext2_ino_t ino, const char *name,
+		      void *value, size_t valuelen)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_xattr_handle *h;
+	errcode_t err;
+	int ret = 0;
+
+	err = ext2fs_xattrs_open(fs, ino, &h);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_xattrs_read(h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_close;
+	}
+
+	err = ext2fs_xattr_set(h, name, value, valuelen);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_close;
+	}
+
+out_close:
+	err = ext2fs_xattrs_close(&h);
+	if (err && !ret)
+		ret = translate_error(fs, ino, err);
+	return ret;
+}
+
+static int propagate_default_acls(struct fuse4fs *ff, ext2_ino_t parent,
+				  ext2_ino_t child, mode_t mode)
+{
+	void *def;
+	size_t deflen;
+	int ret;
+
+	if (!ff->acl || S_ISDIR(mode))
+		return 0;
+
+	ret = __getxattr(ff, parent, XATTR_NAME_POSIX_ACL_DEFAULT, &def,
+			 &deflen);
+	switch (ret) {
+	case -ENODATA:
+	case -ENOENT:
+		/* no default acl */
+		return 0;
+	case 0:
+		break;
+	default:
+		return ret;
+	}
+
+	ret = __setxattr(ff, child, XATTR_NAME_POSIX_ACL_DEFAULT, def, deflen);
+	ext2fs_free_mem(&def);
+	return ret;
+}
+
+static inline void fuse4fs_set_uid(struct ext2_inode_large *inode, uid_t uid)
+{
+	inode->i_uid = uid;
+	ext2fs_set_i_uid_high(*inode, uid >> 16);
+}
+
+static inline void fuse4fs_set_gid(struct ext2_inode_large *inode, gid_t gid)
+{
+	inode->i_gid = gid;
+	ext2fs_set_i_gid_high(*inode, gid >> 16);
+}
+
+static int fuse4fs_new_child_gid(struct fuse4fs *ff, ext2_ino_t parent,
+				 gid_t *gid, int *parent_sgid)
+{
+	struct ext2_inode_large inode;
+	struct fuse_context *ctxt = fuse_get_context();
+	errcode_t err;
+
+	err = fuse4fs_read_inode(ff->fs, parent, &inode);
+	if (err)
+		return translate_error(ff->fs, parent, err);
+
+	if (inode.i_mode & S_ISGID) {
+		if (parent_sgid)
+			*parent_sgid = 1;
+		*gid = inode.i_gid;
+	} else {
+		if (parent_sgid)
+			*parent_sgid = 0;
+		*gid = ctxt->gid;
+	}
+
+	return 0;
+}
+
+/*
+ * Flush dirty data to disk if we're running in dirsync mode.  If @flushed is a
+ * non-null pointer, this function sets @flushed to 1 if we decided to flush
+ * data, or 0 if not.
+ */
+static inline int fuse4fs_dirsync_flush(struct fuse4fs *ff, ext2_ino_t ino,
+					int *flushed)
+{
+	struct ext2_inode_large inode;
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+
+	if (ff->dirsync)
+		goto flush;
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, 0, err);
+
+	if (inode.i_flags & EXT2_DIRSYNC_FL)
+		goto flush;
+
+	if (flushed)
+		*flushed = 0;
+	return 0;
+flush:
+	err = ext2fs_flush2(fs, 0);
+	if (err)
+		return translate_error(fs, 0, err);
+
+	if (flushed)
+		*flushed = 1;
+	return 0;
+}
+
+static void fuse4fs_set_extra_isize(struct fuse4fs *ff, ext2_ino_t ino,
+				    struct ext2_inode_large *inode)
+{
+	ext2_filsys fs = ff->fs;
+	size_t extra = sizeof(struct ext2_inode_large) -
+		EXT2_GOOD_OLD_INODE_SIZE;
+
+	if (ext2fs_has_feature_extra_isize(fs->super)) {
+		dbg_printf(ff, "%s: ino=%u extra=%zu want=%u min=%u\n",
+			   __func__, ino, extra, fs->super->s_want_extra_isize,
+			   fs->super->s_min_extra_isize);
+
+		if (fs->super->s_want_extra_isize > extra)
+			extra = fs->super->s_want_extra_isize;
+		if (fs->super->s_min_extra_isize > extra)
+			extra = fs->super->s_min_extra_isize;
+	}
+
+	inode->i_extra_isize = extra;
+}
+
+static int op_mknod(const char *path, mode_t mode, dev_t dev)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	ext2_ino_t parent, child;
+	char *temp_path;
+	errcode_t err;
+	char *node_name, a;
+	int filetype;
+	struct ext2_inode_large inode;
+	gid_t gid;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: path=%s mode=0%o dev=0x%x\n", __func__, path, mode,
+		   (unsigned int)dev);
+	temp_path = strdup(path);
+	if (!temp_path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name = strrchr(temp_path, '/');
+	if (!node_name) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name++;
+	a = *node_name;
+	*node_name = 0;
+
+	fs = fuse4fs_start(ff);
+	if (!fs_can_allocate(ff, 2)) {
+		ret = -ENOSPC;
+		goto out2;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
+			   &parent);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+
+	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	if (ret)
+		goto out2;
+
+	*node_name = a;
+
+	if (LINUX_S_ISCHR(mode))
+		filetype = EXT2_FT_CHRDEV;
+	else if (LINUX_S_ISBLK(mode))
+		filetype = EXT2_FT_BLKDEV;
+	else if (LINUX_S_ISFIFO(mode))
+		filetype = EXT2_FT_FIFO;
+	else if (LINUX_S_ISSOCK(mode))
+		filetype = EXT2_FT_SOCK;
+	else {
+		ret = -EINVAL;
+		goto out2;
+	}
+
+	err = fuse4fs_new_child_gid(ff, parent, &gid, NULL);
+	if (err)
+		goto out2;
+
+	err = ext2fs_new_inode(fs, parent, mode, 0, &child);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+
+	dbg_printf(ff, "%s: create ino=%d/name=%s in dir=%d\n", __func__, child,
+		   node_name, parent);
+	err = ext2fs_link(fs, parent, node_name, child,
+			  filetype | EXT2FS_LINK_EXPAND);
+	if (err) {
+		ret = translate_error(fs, parent, err);
+		goto out2;
+	}
+
+	ret = update_mtime(fs, parent, NULL);
+	if (ret)
+		goto out2;
+
+	memset(&inode, 0, sizeof(inode));
+	inode.i_mode = mode;
+
+	if (dev & ~0xFFFF)
+		inode.i_block[1] = dev;
+	else
+		inode.i_block[0] = dev;
+	inode.i_links_count = 1;
+	fuse4fs_set_extra_isize(ff, child, &inode);
+	fuse4fs_set_uid(&inode, ctxt->uid);
+	fuse4fs_set_gid(&inode, gid);
+
+	err = ext2fs_write_new_inode(fs, child, EXT2_INODE(&inode));
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+
+	inode.i_generation = ff->next_generation++;
+	init_times(&inode);
+	err = fuse4fs_write_inode(fs, child, &inode);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+
+	ext2fs_inode_alloc_stats2(fs, child, 1, 0);
+
+	ret = propagate_default_acls(ff, parent, child, inode.i_mode);
+	if (ret)
+		goto out2;
+
+	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+	if (ret)
+		goto out2;
+
+out2:
+	fuse4fs_finish(ff, ret);
+out:
+	free(temp_path);
+	return ret;
+}
+
+static int op_mkdir(const char *path, mode_t mode)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	ext2_ino_t parent, child;
+	char *temp_path;
+	errcode_t err;
+	char *node_name, a;
+	struct ext2_inode_large inode;
+	char *block;
+	blk64_t blk;
+	int ret = 0;
+	gid_t gid;
+	int parent_sgid;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: path=%s mode=0%o\n", __func__, path, mode);
+	temp_path = strdup(path);
+	if (!temp_path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name = strrchr(temp_path, '/');
+	if (!node_name) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name++;
+	a = *node_name;
+	*node_name = 0;
+
+	fs = fuse4fs_start(ff);
+	if (!fs_can_allocate(ff, 1)) {
+		ret = -ENOSPC;
+		goto out2;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
+			   &parent);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+
+	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	if (ret)
+		goto out2;
+
+	err = fuse4fs_new_child_gid(ff, parent, &gid, &parent_sgid);
+	if (err)
+		goto out2;
+
+	*node_name = a;
+
+	err = ext2fs_mkdir2(fs, parent, 0, 0, EXT2FS_LINK_EXPAND,
+			    node_name, NULL);
+	if (err) {
+		ret = translate_error(fs, parent, err);
+		goto out2;
+	}
+
+	ret = update_mtime(fs, parent, NULL);
+	if (ret)
+		goto out2;
+
+	/* Still have to update the uid/gid of the dir */
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
+			   &child);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+	dbg_printf(ff, "%s: created ino=%d/path=%s in dir=%d\n", __func__, child,
+		   node_name, parent);
+
+	err = fuse4fs_read_inode(fs, child, &inode);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+
+	fuse4fs_set_extra_isize(ff, child, &inode);
+	fuse4fs_set_uid(&inode, ctxt->uid);
+	fuse4fs_set_gid(&inode, gid);
+	inode.i_mode = LINUX_S_IFDIR | (mode & ~S_ISUID);
+	if (parent_sgid)
+		inode.i_mode |= S_ISGID;
+	inode.i_generation = ff->next_generation++;
+	init_times(&inode);
+
+	err = fuse4fs_write_inode(fs, child, &inode);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+
+	/* Rewrite the directory block checksum, having set i_generation */
+	if ((inode.i_flags & EXT4_INLINE_DATA_FL) ||
+	    !ext2fs_has_feature_metadata_csum(fs->super))
+		goto out2;
+	err = ext2fs_new_dir_block(fs, child, parent, &block);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+	err = ext2fs_bmap2(fs, child, EXT2_INODE(&inode), NULL, 0, 0,
+			   NULL, &blk);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out3;
+	}
+	err = ext2fs_write_dir_block4(fs, blk, block, 0, child);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out3;
+	}
+
+	ret = propagate_default_acls(ff, parent, child, inode.i_mode);
+	if (ret)
+		goto out3;
+
+	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+	if (ret)
+		goto out3;
+
+out3:
+	ext2fs_free_mem(&block);
+out2:
+	fuse4fs_finish(ff, ret);
+out:
+	free(temp_path);
+	return ret;
+}
+
+static int fuse4fs_unlink(struct fuse4fs *ff, const char *path,
+			  ext2_ino_t *parent)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	ext2_ino_t dir;
+	char *filename = strdup(path);
+	char *base_name;
+	int ret;
+
+	base_name = strrchr(filename, '/');
+	if (base_name) {
+		*base_name++ = '\0';
+		err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, filename,
+				   &dir);
+		if (err) {
+			free(filename);
+			return translate_error(fs, 0, err);
+		}
+	} else {
+		dir = EXT2_ROOT_INO;
+		base_name = filename;
+	}
+
+	ret = check_inum_access(ff, dir, W_OK);
+	if (ret) {
+		free(filename);
+		return ret;
+	}
+
+	dbg_printf(ff, "%s: unlinking name=%s from dir=%d\n", __func__,
+		   base_name, dir);
+	err = ext2fs_unlink(fs, dir, base_name, 0, 0);
+	free(filename);
+	if (err)
+		return translate_error(fs, dir, err);
+
+	ret = update_mtime(fs, dir, NULL);
+	if (ret)
+		return ret;
+
+	if (parent)
+		*parent = dir;
+	return 0;
+}
+
+static int remove_ea_inodes(struct fuse4fs *ff, ext2_ino_t ino,
+			    struct ext2_inode_large *inode)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_xattr_handle *h;
+	errcode_t err;
+	int ret = 0;
+
+	/*
+	 * The xattr handle maintains its own private copy of the inode, so
+	 * write ours to disk so that we can read it.
+	 */
+	err = fuse4fs_write_inode(fs, ino, inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_xattrs_open(fs, ino, &h);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_xattrs_read(h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_close;
+	}
+
+	err = ext2fs_xattr_remove_all(h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_close;
+	}
+
+out_close:
+	ext2fs_xattrs_close(&h);
+	if (ret)
+		return ret;
+
+	/* Now read the inode back in. */
+	err = fuse4fs_read_inode(fs, ino, inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
+static int remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	struct ext2_inode_large inode;
+	int ret = 0;
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	dbg_printf(ff, "%s: put ino=%d links=%d\n", __func__, ino,
+		   inode.i_links_count);
+
+	switch (inode.i_links_count) {
+	case 0:
+		return 0; /* XXX: already done? */
+	case 1:
+		inode.i_links_count--;
+		ext2fs_set_dtime(fs, EXT2_INODE(&inode));
+		break;
+	default:
+		inode.i_links_count--;
+	}
+
+	ret = update_ctime(fs, ino, &inode);
+	if (ret)
+		return ret;
+
+	if (inode.i_links_count)
+		goto write_out;
+
+	if (ext2fs_has_feature_ea_inode(fs->super)) {
+		ret = remove_ea_inodes(ff, ino, &inode);
+		if (ret)
+			return ret;
+	}
+
+	/* Nobody holds this file; free its blocks! */
+	err = ext2fs_free_ext_attr(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	if (ext2fs_inode_has_valid_blocks2(fs, EXT2_INODE(&inode))) {
+		err = ext2fs_punch(fs, ino, EXT2_INODE(&inode), NULL,
+				   0, ~0ULL);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	ext2fs_inode_alloc_stats2(fs, ino, -1,
+				  LINUX_S_ISDIR(inode.i_mode));
+
+write_out:
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
+static int __op_unlink(struct fuse4fs *ff, const char *path)
+{
+	ext2_filsys fs = ff->fs;
+	ext2_ino_t parent, ino;
+	errcode_t err;
+	int ret = 0;
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+
+	ret = check_inum_access(ff, ino, W_OK);
+	if (ret)
+		goto out;
+
+	ret = fuse4fs_unlink(ff, path, &parent);
+	if (ret)
+		goto out;
+
+	ret = remove_inode(ff, ino);
+	if (ret)
+		goto out;
+
+	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+	if (ret)
+		goto out;
+
+out:
+	return ret;
+}
+
+static int op_unlink(const char *path)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	int ret;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fuse4fs_start(ff);
+	ret = __op_unlink(ff, path);
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+struct rd_struct {
+	ext2_ino_t	parent;
+	int		empty;
+};
+
+static int rmdir_proc(ext2_ino_t dir EXT2FS_ATTR((unused)),
+		      int	entry EXT2FS_ATTR((unused)),
+		      struct ext2_dir_entry *dirent,
+		      int	offset EXT2FS_ATTR((unused)),
+		      int	blocksize EXT2FS_ATTR((unused)),
+		      char	*buf EXT2FS_ATTR((unused)),
+		      void	*private)
+{
+	struct rd_struct *rds = (struct rd_struct *) private;
+
+	if (dirent->inode == 0)
+		return 0;
+	if (((dirent->name_len & 0xFF) == 1) && (dirent->name[0] == '.'))
+		return 0;
+	if (((dirent->name_len & 0xFF) == 2) && (dirent->name[0] == '.') &&
+	    (dirent->name[1] == '.')) {
+		rds->parent = dirent->inode;
+		return 0;
+	}
+	rds->empty = 0;
+	return 0;
+}
+
+static int __op_rmdir(struct fuse4fs *ff, const char *path)
+{
+	ext2_filsys fs = ff->fs;
+	ext2_ino_t parent, child;
+	errcode_t err;
+	struct ext2_inode_large inode;
+	struct rd_struct rds;
+	int ret = 0;
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &child);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+	dbg_printf(ff, "%s: rmdir path=%s ino=%d\n", __func__, path, child);
+
+	ret = check_inum_access(ff, child, W_OK);
+	if (ret)
+		goto out;
+
+	rds.parent = 0;
+	rds.empty = 1;
+
+	err = ext2fs_dir_iterate2(fs, child, 0, 0, rmdir_proc, &rds);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out;
+	}
+
+	/* the kernel checks parent permissions before emptiness */
+	if (rds.parent == 0) {
+		ret = translate_error(fs, child, EXT2_ET_FILESYSTEM_CORRUPTED);
+		goto out;
+	}
+
+	ret = check_inum_access(ff, rds.parent, W_OK);
+	if (ret)
+		goto out;
+
+	if (rds.empty == 0) {
+		ret = -ENOTEMPTY;
+		goto out;
+	}
+
+	ret = fuse4fs_unlink(ff, path, &parent);
+	if (ret)
+		goto out;
+	/* Directories have to be "removed" twice. */
+	ret = remove_inode(ff, child);
+	if (ret)
+		goto out;
+	ret = remove_inode(ff, child);
+	if (ret)
+		goto out;
+
+	if (rds.parent) {
+		dbg_printf(ff, "%s: decr dir=%d link count\n", __func__,
+			   rds.parent);
+		err = fuse4fs_read_inode(fs, rds.parent, &inode);
+		if (err) {
+			ret = translate_error(fs, rds.parent, err);
+			goto out;
+		}
+		if (inode.i_links_count > 1)
+			inode.i_links_count--;
+		ret = update_mtime(fs, rds.parent, &inode);
+		if (ret)
+			goto out;
+		err = fuse4fs_write_inode(fs, rds.parent, &inode);
+		if (err) {
+			ret = translate_error(fs, rds.parent, err);
+			goto out;
+		}
+	}
+
+	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+	if (ret)
+		goto out;
+
+out:
+	return ret;
+}
+
+static int op_rmdir(const char *path)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	int ret;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fuse4fs_start(ff);
+	ret = __op_rmdir(ff, path);
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int op_symlink(const char *src, const char *dest)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	ext2_ino_t parent, child;
+	char *temp_path;
+	errcode_t err;
+	char *node_name, a;
+	struct ext2_inode_large inode;
+	gid_t gid;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: symlink %s to %s\n", __func__, src, dest);
+	temp_path = strdup(dest);
+	if (!temp_path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name = strrchr(temp_path, '/');
+	if (!node_name) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name++;
+	a = *node_name;
+	*node_name = 0;
+
+	fs = fuse4fs_start(ff);
+	if (!fs_can_allocate(ff, 1)) {
+		ret = -ENOSPC;
+		goto out2;
+	}
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
+			   &parent);
+	*node_name = a;
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+
+	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	if (ret)
+		goto out2;
+
+	err = fuse4fs_new_child_gid(ff, parent, &gid, NULL);
+	if (err)
+		goto out2;
+
+	/* Create symlink */
+	err = ext2fs_symlink(fs, parent, 0, node_name, src);
+	if (err == EXT2_ET_DIR_NO_SPACE) {
+		err = ext2fs_expand_dir(fs, parent);
+		if (err) {
+			ret = translate_error(fs, parent, err);
+			goto out2;
+		}
+
+		err = ext2fs_symlink(fs, parent, 0, node_name, src);
+	}
+	if (err) {
+		ret = translate_error(fs, parent, err);
+		goto out2;
+	}
+
+	/* Update parent dir's mtime */
+	ret = update_mtime(fs, parent, NULL);
+	if (ret)
+		goto out2;
+
+	/* Still have to update the uid/gid of the symlink */
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
+			   &child);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+	dbg_printf(ff, "%s: symlinking ino=%d/name=%s to dir=%d\n", __func__,
+		   child, node_name, parent);
+
+	err = fuse4fs_read_inode(fs, child, &inode);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+
+	fuse4fs_set_extra_isize(ff, child, &inode);
+	fuse4fs_set_uid(&inode, ctxt->uid);
+	fuse4fs_set_gid(&inode, gid);
+	inode.i_generation = ff->next_generation++;
+	init_times(&inode);
+
+	err = fuse4fs_write_inode(fs, child, &inode);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+
+	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+	if (ret)
+		goto out2;
+
+out2:
+	fuse4fs_finish(ff, ret);
+out:
+	free(temp_path);
+	return ret;
+}
+
+struct update_dotdot {
+	ext2_ino_t new_dotdot;
+};
+
+static int update_dotdot_helper(ext2_ino_t dir EXT2FS_ATTR((unused)),
+				int entry EXT2FS_ATTR((unused)),
+				struct ext2_dir_entry *dirent,
+				int offset EXT2FS_ATTR((unused)),
+				int blocksize EXT2FS_ATTR((unused)),
+				char *buf EXT2FS_ATTR((unused)),
+				void *priv_data)
+{
+	struct update_dotdot *ud = priv_data;
+
+	if (ext2fs_dirent_name_len(dirent) == 2 &&
+	    dirent->name[0] == '.' && dirent->name[1] == '.') {
+		dirent->inode = ud->new_dotdot;
+		return DIRENT_CHANGED | DIRENT_ABORT;
+	}
+
+	return 0;
+}
+
+static int op_rename(const char *from, const char *to,
+		     unsigned int flags EXT2FS_ATTR((unused)))
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	errcode_t err;
+	ext2_ino_t from_ino, to_ino, to_dir_ino, from_dir_ino;
+	char *temp_to = NULL, *temp_from = NULL;
+	char *cp, a;
+	struct ext2_inode inode;
+	struct update_dotdot ud;
+	int flushed = 0;
+	int ret = 0;
+
+	/* renameat2 is not supported */
+	if (flags)
+		return -ENOSYS;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: renaming %s to %s\n", __func__, from, to);
+	fs = fuse4fs_start(ff);
+	if (!fs_can_allocate(ff, 5)) {
+		ret = -ENOSPC;
+		goto out;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, from, &from_ino);
+	if (err || from_ino == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, to, &to_ino);
+	if (err && err != EXT2_ET_FILE_NOT_FOUND) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+
+	if (err == EXT2_ET_FILE_NOT_FOUND)
+		to_ino = 0;
+
+	/* Already the same file? */
+	if (to_ino != 0 && to_ino == from_ino) {
+		ret = 0;
+		goto out;
+	}
+
+	ret = check_inum_access(ff, from_ino, W_OK);
+	if (ret)
+		goto out;
+
+	if (to_ino) {
+		ret = check_inum_access(ff, to_ino, W_OK);
+		if (ret)
+			goto out;
+	}
+
+	temp_to = strdup(to);
+	if (!temp_to) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	temp_from = strdup(from);
+	if (!temp_from) {
+		ret = -ENOMEM;
+		goto out2;
+	}
+
+	/* Find parent dir of the source and check write access */
+	cp = strrchr(temp_from, '/');
+	if (!cp) {
+		ret = -EINVAL;
+		goto out2;
+	}
+
+	a = *(cp + 1);
+	*(cp + 1) = 0;
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_from,
+			   &from_dir_ino);
+	*(cp + 1) = a;
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+	if (from_dir_ino == 0) {
+		ret = -ENOENT;
+		goto out2;
+	}
+
+	ret = check_inum_access(ff, from_dir_ino, W_OK);
+	if (ret)
+		goto out2;
+
+	/* Find parent dir of the destination and check write access */
+	cp = strrchr(temp_to, '/');
+	if (!cp) {
+		ret = -EINVAL;
+		goto out2;
+	}
+
+	a = *(cp + 1);
+	*(cp + 1) = 0;
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_to,
+			   &to_dir_ino);
+	*(cp + 1) = a;
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+	if (to_dir_ino == 0) {
+		ret = -ENOENT;
+		goto out2;
+	}
+
+	ret = check_inum_access(ff, to_dir_ino, W_OK);
+	if (ret)
+		goto out2;
+
+	/* If the target exists, unlink it first */
+	if (to_ino != 0) {
+		err = ext2fs_read_inode(fs, to_ino, &inode);
+		if (err) {
+			ret = translate_error(fs, to_ino, err);
+			goto out2;
+		}
+
+		dbg_printf(ff, "%s: unlinking %s ino=%d\n", __func__,
+			   LINUX_S_ISDIR(inode.i_mode) ? "dir" : "file",
+			   to_ino);
+		if (LINUX_S_ISDIR(inode.i_mode))
+			ret = __op_rmdir(ff, to);
+		else
+			ret = __op_unlink(ff, to);
+		if (ret)
+			goto out2;
+	}
+
+	/* Get ready to do the move */
+	err = ext2fs_read_inode(fs, from_ino, &inode);
+	if (err) {
+		ret = translate_error(fs, from_ino, err);
+		goto out2;
+	}
+
+	/* Link in the new file */
+	dbg_printf(ff, "%s: linking ino=%d/path=%s to dir=%d\n", __func__,
+		   from_ino, cp + 1, to_dir_ino);
+	err = ext2fs_link(fs, to_dir_ino, cp + 1, from_ino,
+			  ext2_file_type(inode.i_mode) | EXT2FS_LINK_EXPAND);
+	if (err) {
+		ret = translate_error(fs, to_dir_ino, err);
+		goto out2;
+	}
+
+	/* Update '..' pointer if dir */
+	err = ext2fs_read_inode(fs, from_ino, &inode);
+	if (err) {
+		ret = translate_error(fs, from_ino, err);
+		goto out2;
+	}
+
+	if (LINUX_S_ISDIR(inode.i_mode)) {
+		ud.new_dotdot = to_dir_ino;
+		dbg_printf(ff, "%s: updating .. entry for dir=%d\n", __func__,
+			   to_dir_ino);
+		err = ext2fs_dir_iterate2(fs, from_ino, 0, NULL,
+					  update_dotdot_helper, &ud);
+		if (err) {
+			ret = translate_error(fs, from_ino, err);
+			goto out2;
+		}
+
+		/* Decrease from_dir_ino's links_count */
+		dbg_printf(ff, "%s: moving linkcount from dir=%d to dir=%d\n",
+			   __func__, from_dir_ino, to_dir_ino);
+		err = ext2fs_read_inode(fs, from_dir_ino, &inode);
+		if (err) {
+			ret = translate_error(fs, from_dir_ino, err);
+			goto out2;
+		}
+		inode.i_links_count--;
+		err = ext2fs_write_inode(fs, from_dir_ino, &inode);
+		if (err) {
+			ret = translate_error(fs, from_dir_ino, err);
+			goto out2;
+		}
+
+		/* Increase to_dir_ino's links_count */
+		err = ext2fs_read_inode(fs, to_dir_ino, &inode);
+		if (err) {
+			ret = translate_error(fs, to_dir_ino, err);
+			goto out2;
+		}
+		inode.i_links_count++;
+		err = ext2fs_write_inode(fs, to_dir_ino, &inode);
+		if (err) {
+			ret = translate_error(fs, to_dir_ino, err);
+			goto out2;
+		}
+	}
+
+	/* Update timestamps */
+	ret = update_ctime(fs, from_ino, NULL);
+	if (ret)
+		goto out2;
+
+	ret = update_mtime(fs, to_dir_ino, NULL);
+	if (ret)
+		goto out2;
+
+	/* Remove the old file */
+	ret = fuse4fs_unlink(ff, from, NULL);
+	if (ret)
+		goto out2;
+
+	ret = fuse4fs_dirsync_flush(ff, from_dir_ino, &flushed);
+	if (ret)
+		goto out2;
+
+	if (from_dir_ino != to_dir_ino && !flushed) {
+		ret = fuse4fs_dirsync_flush(ff, to_dir_ino, NULL);
+		if (ret)
+			goto out2;
+	}
+
+out2:
+	free(temp_from);
+	free(temp_to);
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int op_link(const char *src, const char *dest)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	char *temp_path;
+	errcode_t err;
+	char *node_name, a;
+	ext2_ino_t parent, ino;
+	struct ext2_inode_large inode;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: src=%s dest=%s\n", __func__, src, dest);
+	temp_path = strdup(dest);
+	if (!temp_path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name = strrchr(temp_path, '/');
+	if (!node_name) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name++;
+	a = *node_name;
+	*node_name = 0;
+
+	fs = fuse4fs_start(ff);
+	if (!fs_can_allocate(ff, 2)) {
+		ret = -ENOSPC;
+		goto out2;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
+			   &parent);
+	*node_name = a;
+	if (err) {
+		err = -ENOENT;
+		goto out2;
+	}
+
+	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	if (ret)
+		goto out2;
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, src, &ino);
+	if (err || ino == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	ret = check_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	if (ret)
+		goto out2;
+
+	inode.i_links_count++;
+	ret = update_ctime(fs, ino, &inode);
+	if (ret)
+		goto out2;
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	dbg_printf(ff, "%s: linking ino=%d/name=%s to dir=%d\n", __func__, ino,
+		   node_name, parent);
+	err = ext2fs_link(fs, parent, node_name, ino,
+			  ext2_file_type(inode.i_mode) | EXT2FS_LINK_EXPAND);
+	if (err) {
+		ret = translate_error(fs, parent, err);
+		goto out2;
+	}
+
+	ret = update_mtime(fs, parent, NULL);
+	if (ret)
+		goto out2;
+
+	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+	if (ret)
+		goto out2;
+
+out2:
+	fuse4fs_finish(ff, ret);
+out:
+	free(temp_path);
+	return ret;
+}
+
+/* Obtain group ids of the process that sent us a command(?) */
+static int get_req_groups(struct fuse4fs *ff, gid_t **gids, size_t *nr_gids)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	gid_t *array;
+	int nr = 32;	/* nobody has more than 32 groups right? */
+	int ret;
+
+	do {
+		err = ext2fs_get_array(nr, sizeof(gid_t), &array);
+		if (err)
+			return translate_error(fs, 0, err);
+
+		ret = fuse_getgroups(nr, array);
+		if (ret < 0) {
+			/*
+			 * If there's an error, we failed to find the group
+			 * membership of the process that initiated the file
+			 * change, either because the process went away or
+			 * because there's no Linux procfs.  Regardless of the
+			 * cause, we return -ENOENT.
+			 */
+			ext2fs_free_mem(&array);
+			return -ENOENT;
+		}
+
+		if (ret <= nr) {
+			*gids = array;
+			*nr_gids = ret;
+			return 0;
+		}
+
+		ext2fs_free_mem(&array);
+		nr = ret;
+	} while (0);
+
+	/* shut up gcc */
+	return -ENOMEM;
+}
+
+/*
+ * Is this file's group id in the set of groups associated with the process
+ * that initiated the fuse request?  Returns 1 for yes, 0 for no, or a negative
+ * errno.
+ */
+static int in_file_group(struct fuse_context *ctxt,
+			 const struct ext2_inode_large *inode)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	gid_t *gids = NULL;
+	size_t i, nr_gids = 0;
+	gid_t gid = inode_gid(*inode);
+	int ret;
+
+	/* If the inode gid matches the process' primary group, we're done. */
+	if (ctxt->gid == gid)
+		return 1;
+
+	ret = get_req_groups(ff, &gids, &nr_gids);
+	if (ret == -ENOENT) {
+		/* magic return code for "could not get caller group info" */
+		return 0;
+	}
+	if (ret < 0)
+		return ret;
+
+	ret = 0;
+	for (i = 0; i < nr_gids; i++) {
+		if (gids[i] == gid) {
+			ret = 1;
+			break;
+		}
+	}
+
+	ext2fs_free_mem(&gids);
+	return ret;
+}
+
+static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	errcode_t err;
+	ext2_ino_t ino;
+	struct ext2_inode_large inode;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	ret = fuse4fs_file_ino(ff, path, fi, &ino);
+	if (ret)
+		goto out;
+	dbg_printf(ff, "%s: path=%s mode=0%o ino=%d\n", __func__, path, mode, ino);
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+	ret = check_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	if (ret)
+		goto out;
+
+	if (want_check_owner(ff, ctxt) && ctxt->uid != inode_uid(inode)) {
+		ret = -EPERM;
+		goto out;
+	}
+
+	/*
+	 * XXX: We should really check that the inode gid is not in /any/
+	 * of the user's groups, but FUSE only tells us about the primary
+	 * group.
+	 */
+	if (!is_superuser(ff, ctxt)) {
+		ret = in_file_group(ctxt, &inode);
+		if (ret < 0)
+			goto out;
+
+		if (!ret)
+			mode &= ~S_ISGID;
+	}
+
+	inode.i_mode &= ~0xFFF;
+	inode.i_mode |= mode & 0xFFF;
+
+	dbg_printf(ff, "%s: path=%s new_mode=0%o ino=%d\n", __func__,
+		   path, inode.i_mode, ino);
+
+	ret = update_ctime(fs, ino, &inode);
+	if (ret)
+		goto out;
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int op_chown(const char *path, uid_t owner, gid_t group,
+		    struct fuse_file_info *fi)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	errcode_t err;
+	ext2_ino_t ino;
+	struct ext2_inode_large inode;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	ret = fuse4fs_file_ino(ff, path, fi, &ino);
+	if (ret)
+		goto out;
+	dbg_printf(ff, "%s: path=%s owner=%d group=%d ino=%d\n", __func__,
+		   path, owner, group, ino);
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+	ret = check_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	if (ret)
+		goto out;
+
+	/* FUSE seems to feed us ~0 to mean "don't change" */
+	if (owner != (uid_t) ~0) {
+		/* Only root gets to change UID. */
+		if (want_check_owner(ff, ctxt) &&
+		    !(inode_uid(inode) == ctxt->uid && owner == ctxt->uid)) {
+			ret = -EPERM;
+			goto out;
+		}
+		fuse4fs_set_uid(&inode, owner);
+	}
+
+	if (group != (gid_t) ~0) {
+		/* Only root or the owner get to change GID. */
+		if (want_check_owner(ff, ctxt) &&
+		    inode_uid(inode) != ctxt->uid) {
+			ret = -EPERM;
+			goto out;
+		}
+
+		/* XXX: We /should/ check group membership but FUSE */
+		fuse4fs_set_gid(&inode, group);
+	}
+
+	ret = update_ctime(fs, ino, &inode);
+	if (ret)
+		goto out;
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int fuse4fs_punch_posteof(struct fuse4fs *ff, ext2_ino_t ino,
+				 off_t new_size)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_inode_large inode;
+	blk64_t truncate_block = FUSE4FS_B_TO_FSB(ff, new_size);
+	errcode_t err;
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_punch(fs, ino, EXT2_INODE(&inode), 0, truncate_block,
+			   ~0ULL);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
+static int fuse4fs_truncate(struct fuse4fs *ff, ext2_ino_t ino, off_t new_size)
+{
+	ext2_filsys fs = ff->fs;
+	ext2_file_t file;
+	__u64 old_isize;
+	errcode_t err;
+	int ret = 0;
+
+	err = ext2fs_file_open(fs, ino, EXT2_FILE_WRITE, &file);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_file_get_lsize(file, &old_isize);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_close;
+	}
+
+	dbg_printf(ff, "%s: ino=%u isize=0x%llx new_size=0x%llx\n", __func__,
+		   ino,
+		   (unsigned long long)old_isize,
+		   (unsigned long long)new_size);
+
+	err = ext2fs_file_set_size2(file, new_size);
+	if (err)
+		ret = translate_error(fs, ino, err);
+
+out_close:
+	err = ext2fs_file_close(file);
+	if (ret)
+		return ret;
+	if (err)
+		return translate_error(fs, ino, err);
+
+	ret = update_mtime(fs, ino, NULL);
+	if (ret)
+		return ret;
+
+	/*
+	 * Truncating to the current size is usually understood to mean that
+	 * we should clear out post-EOF preallocations.
+	 */
+	if (new_size == old_isize)
+		return fuse4fs_punch_posteof(ff, ino, new_size);
+
+	return 0;
+}
+
+static int op_truncate(const char *path, off_t len, struct fuse_file_info *fi)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_ino_t ino;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fuse4fs_start(ff);
+	ret = fuse4fs_file_ino(ff, path, fi, &ino);
+	if (ret)
+		goto out;
+	dbg_printf(ff, "%s: ino=%d len=%jd\n", __func__, ino, (intmax_t) len);
+
+	ret = check_inum_access(ff, ino, W_OK);
+	if (ret)
+		goto out;
+
+	ret = fuse4fs_truncate(ff, ino, len);
+	if (ret)
+		goto out;
+
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+#ifdef __linux__
+static void detect_linux_executable_open(int kernel_flags, int *access_check,
+				  int *e2fs_open_flags)
+{
+	/*
+	 * On Linux, execve will bleed __FMODE_EXEC into the file mode flags,
+	 * and FUSE is more than happy to let that slip through.
+	 */
+	if (kernel_flags & 0x20) {
+		*access_check = X_OK;
+		*e2fs_open_flags &= ~EXT2_FILE_WRITE;
+	}
+}
+#else
+static void detect_linux_executable_open(int kernel_flags, int *access_check,
+				  int *e2fs_open_flags)
+{
+	/* empty */
+}
+#endif /* __linux__ */
+
+static int __op_open(struct fuse4fs *ff, const char *path,
+		     struct fuse_file_info *fp)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	struct fuse4fs_file_handle *file;
+	int check = 0, ret = 0;
+
+	dbg_printf(ff, "%s: path=%s oflags=0o%o\n", __func__, path, fp->flags);
+	err = ext2fs_get_mem(sizeof(*file), &file);
+	if (err)
+		return translate_error(fs, 0, err);
+	file->magic = FUSE4FS_FILE_MAGIC;
+
+	file->open_flags = 0;
+	switch (fp->flags & O_ACCMODE) {
+	case O_RDONLY:
+		check = R_OK;
+		break;
+	case O_WRONLY:
+		check = W_OK;
+		file->open_flags |= EXT2_FILE_WRITE;
+		break;
+	case O_RDWR:
+		check = R_OK | W_OK;
+		file->open_flags |= EXT2_FILE_WRITE;
+		break;
+	}
+
+	/*
+	 * If the caller wants to truncate the file, we need to ask for full
+	 * write access even if the caller claims to be appending.
+	 */
+	if ((fp->flags & O_APPEND) && !(fp->flags & O_TRUNC))
+		check |= A_OK;
+
+	detect_linux_executable_open(fp->flags, &check, &file->open_flags);
+
+	if (fp->flags & O_CREAT)
+		file->open_flags |= EXT2_FILE_CREATE;
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &file->ino);
+	if (err || file->ino == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+	dbg_printf(ff, "%s: ino=%d\n", __func__, file->ino);
+
+	ret = check_inum_access(ff, file->ino, check);
+	if (ret) {
+		/*
+		 * In a regular (Linux) fs driver, the kernel will open
+		 * binaries for reading if the user has --x privileges (i.e.
+		 * execute without read).  Since the kernel doesn't have any
+		 * way to tell us if it's opening a file via execve, we'll
+		 * just assume that allowing access is ok if asking for ro mode
+		 * fails but asking for x mode succeeds.  Of course we can
+		 * also employ undocumented hacks (see above).
+		 */
+		if (check == R_OK) {
+			ret = check_inum_access(ff, file->ino, X_OK);
+			if (ret)
+				goto out;
+			check = X_OK;
+		} else
+			goto out;
+	}
+
+	if (fp->flags & O_TRUNC) {
+		ret = fuse4fs_truncate(ff, file->ino, 0);
+		if (ret)
+			goto out;
+	}
+
+	file->check_flags = check;
+	fuse4fs_set_handle(fp, file);
+
+out:
+	if (ret)
+		ext2fs_free_mem(&file);
+	return ret;
+}
+
+static int op_open(const char *path, struct fuse_file_info *fp)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	int ret;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fuse4fs_start(ff);
+	ret = __op_open(ff, path, fp);
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int op_read(const char *path EXT2FS_ATTR((unused)), char *buf,
+		   size_t len, off_t offset,
+		   struct fuse_file_info *fp)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	ext2_filsys fs;
+	ext2_file_t efp;
+	errcode_t err;
+	unsigned int got = 0;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_HANDLE(ff, fh);
+	dbg_printf(ff, "%s: ino=%d off=0x%llx len=0x%zx\n", __func__, fh->ino,
+		   (unsigned long long)offset, len);
+	fs = fuse4fs_start(ff);
+	err = ext2fs_file_open(fs, fh->ino, fh->open_flags, &efp);
+	if (err) {
+		ret = translate_error(fs, fh->ino, err);
+		goto out;
+	}
+
+	err = ext2fs_file_llseek(efp, offset, SEEK_SET, NULL);
+	if (err) {
+		ret = translate_error(fs, fh->ino, err);
+		goto out2;
+	}
+
+	err = ext2fs_file_read(efp, buf, len, &got);
+	if (err) {
+		ret = translate_error(fs, fh->ino, err);
+		goto out2;
+	}
+
+out2:
+	err = ext2fs_file_close(efp);
+	if (ret)
+		goto out;
+	if (err) {
+		ret = translate_error(fs, fh->ino, err);
+		goto out;
+	}
+
+	if (fh->check_flags != X_OK && fuse4fs_is_writeable(ff)) {
+		ret = update_atime(fs, fh->ino);
+		if (ret)
+			goto out;
+	}
+out:
+	fuse4fs_finish(ff, ret);
+	return got ? (int) got : ret;
+}
+
+static int op_write(const char *path EXT2FS_ATTR((unused)),
+		    const char *buf, size_t len, off_t offset,
+		    struct fuse_file_info *fp)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	ext2_filsys fs;
+	ext2_file_t efp;
+	errcode_t err;
+	unsigned int got = 0;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_HANDLE(ff, fh);
+	dbg_printf(ff, "%s: ino=%d off=0x%llx len=0x%zx\n", __func__, fh->ino,
+		   (unsigned long long) offset, len);
+	fs = fuse4fs_start(ff);
+	if (!fuse4fs_is_writeable(ff)) {
+		ret = -EROFS;
+		goto out;
+	}
+
+	if (!fs_can_allocate(ff, FUSE4FS_B_TO_FSB(ff, len))) {
+		ret = -ENOSPC;
+		goto out;
+	}
+
+	err = ext2fs_file_open(fs, fh->ino, fh->open_flags, &efp);
+	if (err) {
+		ret = translate_error(fs, fh->ino, err);
+		goto out;
+	}
+
+	err = ext2fs_file_llseek(efp, offset, SEEK_SET, NULL);
+	if (err) {
+		ret = translate_error(fs, fh->ino, err);
+		goto out2;
+	}
+
+	err = ext2fs_file_write(efp, buf, len, &got);
+	if (err) {
+		ret = translate_error(fs, fh->ino, err);
+		goto out2;
+	}
+
+	err = ext2fs_file_flush(efp);
+	if (err) {
+		got = 0;
+		ret = translate_error(fs, fh->ino, err);
+		goto out2;
+	}
+
+out2:
+	err = ext2fs_file_close(efp);
+	if (ret)
+		goto out;
+	if (err) {
+		ret = translate_error(fs, fh->ino, err);
+		goto out;
+	}
+
+	ret = update_mtime(fs, fh->ino, NULL);
+	if (ret)
+		goto out;
+
+out:
+	fuse4fs_finish(ff, ret);
+	return got ? (int) got : ret;
+}
+
+static int op_release(const char *path EXT2FS_ATTR((unused)),
+		      struct fuse_file_info *fp)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	ext2_filsys fs;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_HANDLE(ff, fh);
+	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	fs = fuse4fs_start(ff);
+
+	if ((fp->flags & O_SYNC) &&
+	    fuse4fs_is_writeable(ff) &&
+	    (fh->open_flags & EXT2_FILE_WRITE)) {
+		err = ext2fs_flush2(fs, EXT2_FLAG_FLUSH_NO_SYNC);
+		if (err)
+			ret = translate_error(fs, fh->ino, err);
+	}
+
+	fp->fh = 0;
+	fuse4fs_finish(ff, ret);
+
+	ext2fs_free_mem(&fh);
+
+	return ret;
+}
+
+static int op_fsync(const char *path EXT2FS_ATTR((unused)),
+		    int datasync EXT2FS_ATTR((unused)),
+		    struct fuse_file_info *fp)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	ext2_filsys fs;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_HANDLE(ff, fh);
+	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	fs = fuse4fs_start(ff);
+	/* For now, flush everything, even if it's slow */
+	if (fuse4fs_is_writeable(ff) && fh->open_flags & EXT2_FILE_WRITE) {
+		err = ext2fs_flush2(fs, 0);
+		if (err)
+			ret = translate_error(fs, fh->ino, err);
+	}
+	fuse4fs_finish(ff, ret);
+
+	return ret;
+}
+
+static int op_statfs(const char *path EXT2FS_ATTR((unused)),
+		     struct statvfs *buf)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	uint64_t fsid, *f;
+	blk64_t overhead, reserved, free;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: path=%s\n", __func__, path);
+	fs = fuse4fs_start(ff);
+	buf->f_bsize = fs->blocksize;
+	buf->f_frsize = 0;
+
+	if (ff->minixdf)
+		overhead = 0;
+	else
+		overhead = fs->desc_blocks +
+			   (blk64_t)fs->group_desc_count *
+			   (fs->inode_blocks_per_group + 2);
+	reserved = ext2fs_r_blocks_count(fs->super);
+	if (!reserved)
+		reserved = ext2fs_blocks_count(fs->super) / 10;
+	free = ext2fs_free_blocks_count(fs->super);
+
+	buf->f_blocks = ext2fs_blocks_count(fs->super) - overhead;
+	buf->f_bfree = free;
+	if (free < reserved)
+		buf->f_bavail = 0;
+	else
+		buf->f_bavail = free - reserved;
+	buf->f_files = fs->super->s_inodes_count;
+	buf->f_ffree = fs->super->s_free_inodes_count;
+	buf->f_favail = fs->super->s_free_inodes_count;
+	f = (uint64_t *)fs->super->s_uuid;
+	fsid = *f;
+	f++;
+	fsid ^= *f;
+	buf->f_fsid = fsid;
+	buf->f_flag = 0;
+	if (ff->opstate != F4OP_WRITABLE)
+		buf->f_flag |= ST_RDONLY;
+	buf->f_namemax = EXT2_NAME_LEN;
+	fuse4fs_finish(ff, 0);
+
+	return 0;
+}
+
+static const char *valid_xattr_prefixes[] = {
+	"user.",
+	"trusted.",
+	"security.",
+	"gnu.",
+	"system.",
+};
+
+static int validate_xattr_name(const char *name)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(valid_xattr_prefixes); i++) {
+		if (!strncmp(name, valid_xattr_prefixes[i],
+					strlen(valid_xattr_prefixes[i])))
+			return 1;
+	}
+
+	return 0;
+}
+
+static int op_getxattr(const char *path, const char *key, char *value,
+		       size_t len)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	void *ptr;
+	size_t plen;
+	ext2_ino_t ino;
+	errcode_t err;
+	int ret = 0;
+
+	if (!validate_xattr_name(key))
+		return -ENODATA;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	if (!ext2fs_has_feature_xattr(fs->super)) {
+		ret = -ENOTSUP;
+		goto out;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	if (err || ino == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
+
+	ret = check_inum_access(ff, ino, R_OK);
+	if (ret)
+		goto out;
+
+	ret = __getxattr(ff, ino, key, &ptr, &plen);
+	if (ret)
+		goto out;
+
+	if (!len) {
+		ret = plen;
+	} else if (len < plen) {
+		ret = -ERANGE;
+	} else {
+		memcpy(value, ptr, plen);
+		ret = plen;
+	}
+
+	ext2fs_free_mem(&ptr);
+out:
+	fuse4fs_finish(ff, ret);
+
+	return ret;
+}
+
+static int count_buffer_space(char *name, char *value EXT2FS_ATTR((unused)),
+			      size_t value_len EXT2FS_ATTR((unused)),
+			      void *data)
+{
+	unsigned int *x = data;
+
+	*x = *x + strlen(name) + 1;
+	return 0;
+}
+
+static int copy_names(char *name, char *value EXT2FS_ATTR((unused)),
+		      size_t value_len EXT2FS_ATTR((unused)), void *data)
+{
+	char **b = data;
+	size_t name_len = strlen(name);
+
+	memcpy(*b, name, name_len + 1);
+	*b = *b + name_len + 1;
+
+	return 0;
+}
+
+static int op_listxattr(const char *path, char *names, size_t len)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	struct ext2_xattr_handle *h;
+	unsigned int bufsz;
+	ext2_ino_t ino;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	if (!ext2fs_has_feature_xattr(fs->super)) {
+		ret = -ENOTSUP;
+		goto out;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	if (err || ino == 0) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+	dbg_printf(ff, "%s: ino=%d\n", __func__, ino);
+
+	ret = check_inum_access(ff, ino, R_OK);
+	if (ret)
+		goto out;
+
+	err = ext2fs_xattrs_open(fs, ino, &h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+	err = ext2fs_xattrs_read(h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	/* Count buffer space needed for names */
+	bufsz = 0;
+	err = ext2fs_xattrs_iterate(h, count_buffer_space, &bufsz);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	if (len == 0) {
+		ret = bufsz;
+		goto out2;
+	} else if (len < bufsz) {
+		ret = -ERANGE;
+		goto out2;
+	}
+
+	/* Copy names out */
+	memset(names, 0, len);
+	err = ext2fs_xattrs_iterate(h, copy_names, &names);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+	ret = bufsz;
+out2:
+	err = ext2fs_xattrs_close(&h);
+	if (err && !ret)
+		ret = translate_error(fs, ino, err);
+out:
+	fuse4fs_finish(ff, ret);
+
+	return ret;
+}
+
+static int op_setxattr(const char *path EXT2FS_ATTR((unused)),
+		       const char *key, const char *value,
+		       size_t len, int flags)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	struct ext2_xattr_handle *h;
+	ext2_ino_t ino;
+	errcode_t err;
+	int ret = 0;
+
+	if (flags & ~(XATTR_CREATE | XATTR_REPLACE))
+		return -EOPNOTSUPP;
+
+	if (!validate_xattr_name(key))
+		return -EINVAL;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	if (!ext2fs_has_feature_xattr(fs->super)) {
+		ret = -ENOTSUP;
+		goto out;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	if (err || ino == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
+
+	ret = check_inum_access(ff, ino, W_OK);
+	if (ret == -EACCES) {
+		ret = -EPERM;
+		goto out;
+	} else if (ret)
+		goto out;
+
+	err = ext2fs_xattrs_open(fs, ino, &h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+	err = ext2fs_xattrs_read(h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	if (flags & (XATTR_CREATE | XATTR_REPLACE)) {
+		void *buf;
+		size_t buflen;
+
+		err = ext2fs_xattr_get(h, key, &buf, &buflen);
+		switch (err) {
+		case EXT2_ET_EA_KEY_NOT_FOUND:
+			if (flags & XATTR_REPLACE) {
+				ret = -ENODATA;
+				goto out2;
+			}
+			break;
+		case 0:
+			ext2fs_free_mem(&buf);
+			if (flags & XATTR_CREATE) {
+				ret = -EEXIST;
+				goto out2;
+			}
+			break;
+		default:
+			ret = translate_error(fs, ino, err);
+			goto out2;
+		}
+	}
+
+	err = ext2fs_xattr_set(h, key, value, len);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	ret = update_ctime(fs, ino, NULL);
+out2:
+	err = ext2fs_xattrs_close(&h);
+	if (!ret && err)
+		ret = translate_error(fs, ino, err);
+out:
+	fuse4fs_finish(ff, ret);
+
+	return ret;
+}
+
+static int op_removexattr(const char *path, const char *key)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	struct ext2_xattr_handle *h;
+	void *buf;
+	size_t buflen;
+	ext2_ino_t ino;
+	errcode_t err;
+	int ret = 0;
+
+	/*
+	 * Once in a while libfuse gives us a no-name xattr to delete as part
+	 * of clearing ACLs.  Just pretend we cleared them.
+	 */
+	if (key[0] == 0)
+		return 0;
+
+	if (!validate_xattr_name(key))
+		return -ENODATA;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	if (!ext2fs_has_feature_xattr(fs->super)) {
+		ret = -ENOTSUP;
+		goto out;
+	}
+
+	if (!fs_can_allocate(ff, 1)) {
+		ret = -ENOSPC;
+		goto out;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	if (err || ino == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
+
+	ret = check_inum_access(ff, ino, W_OK);
+	if (ret)
+		goto out;
+
+	err = ext2fs_xattrs_open(fs, ino, &h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+	err = ext2fs_xattrs_read(h);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	err = ext2fs_xattr_get(h, key, &buf, &buflen);
+	switch (err) {
+	case EXT2_ET_EA_KEY_NOT_FOUND:
+		/*
+		 * ACLs are special snowflakes that require a 0 return when
+		 * the ACL never existed in the first place.
+		 */
+		if (!strncmp(XATTR_SECURITY_PREFIX, key,
+			     XATTR_SECURITY_PREFIX_LEN))
+			ret = 0;
+		else
+			ret = -ENODATA;
+		goto out2;
+	case 0:
+		ext2fs_free_mem(&buf);
+		break;
+	default:
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	err = ext2fs_xattr_remove(h, key);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out2;
+	}
+
+	ret = update_ctime(fs, ino, NULL);
+out2:
+	err = ext2fs_xattrs_close(&h);
+	if (err && !ret)
+		ret = translate_error(fs, ino, err);
+out:
+	fuse4fs_finish(ff, ret);
+
+	return ret;
+}
+
+struct readdir_iter {
+	void *buf;
+	ext2_filsys fs;
+	fuse_fill_dir_t func;
+
+	struct fuse4fs *ff;
+	enum fuse_readdir_flags flags;
+	unsigned int nr;
+	off_t startpos;
+	off_t dirpos;
+};
+
+static inline mode_t dirent_fmode(ext2_filsys fs,
+				   const struct ext2_dir_entry *dirent)
+{
+	if (!ext2fs_has_feature_filetype(fs->super))
+		return 0;
+
+	switch (ext2fs_dirent_file_type(dirent)) {
+	case EXT2_FT_REG_FILE:
+		return S_IFREG;
+	case EXT2_FT_DIR:
+		return S_IFDIR;
+	case EXT2_FT_CHRDEV:
+		return S_IFCHR;
+	case EXT2_FT_BLKDEV:
+		return S_IFBLK;
+	case EXT2_FT_FIFO:
+		return S_IFIFO;
+	case EXT2_FT_SOCK:
+		return S_IFSOCK;
+	case EXT2_FT_SYMLINK:
+		return S_IFLNK;
+	}
+
+	return 0;
+}
+
+static int op_readdir_iter(ext2_ino_t dir EXT2FS_ATTR((unused)),
+			   int entry EXT2FS_ATTR((unused)),
+			   struct ext2_dir_entry *dirent,
+			   int offset EXT2FS_ATTR((unused)),
+			   int blocksize EXT2FS_ATTR((unused)),
+			   char *buf EXT2FS_ATTR((unused)), void *data)
+{
+	struct readdir_iter *i = data;
+	char namebuf[EXT2_NAME_LEN + 1];
+	struct stat stat = {
+		.st_ino = dirent->inode,
+		.st_mode = dirent_fmode(i->fs, dirent),
+	};
+	int ret;
+
+	i->dirpos++;
+	if (i->startpos >= i->dirpos)
+		return 0;
+
+	dbg_printf(i->ff, "READDIR%s ino=%d %u offset=0x%llx\n",
+			i->flags == FUSE_READDIR_PLUS ? "PLUS" : "",
+			dir,
+			i->nr++,
+			(unsigned long long)i->dirpos);
+
+	if (i->flags == FUSE_READDIR_PLUS) {
+		ret = stat_inode(i->fs, dirent->inode, &stat);
+		if (ret)
+			return DIRENT_ABORT;
+	}
+
+	memcpy(namebuf, dirent->name, dirent->name_len & 0xFF);
+	namebuf[dirent->name_len & 0xFF] = 0;
+	ret = i->func(i->buf, namebuf, &stat, i->dirpos , 0);
+	if (ret)
+		return DIRENT_ABORT;
+
+	return 0;
+}
+
+static int op_readdir(const char *path EXT2FS_ATTR((unused)), void *buf,
+		      fuse_fill_dir_t fill_func, off_t offset,
+		      struct fuse_file_info *fp, enum fuse_readdir_flags flags)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	errcode_t err;
+	struct readdir_iter i = {
+		.ff = ff,
+		.dirpos = 0,
+		.startpos = offset,
+		.flags = flags,
+	};
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_HANDLE(ff, fh);
+	dbg_printf(ff, "%s: ino=%d offset=0x%llx\n", __func__, fh->ino,
+			(unsigned long long)offset);
+	i.fs = fuse4fs_start(ff);
+	i.buf = buf;
+	i.func = fill_func;
+	err = ext2fs_dir_iterate2(i.fs, fh->ino, 0, NULL, op_readdir_iter, &i);
+	if (err) {
+		ret = translate_error(i.fs, fh->ino, err);
+		goto out;
+	}
+
+	if (fuse4fs_is_writeable(ff)) {
+		ret = update_atime(i.fs, fh->ino);
+		if (ret)
+			goto out;
+	}
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int op_access(const char *path, int mask)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	errcode_t err;
+	ext2_ino_t ino;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: path=%s mask=0x%x\n", __func__, path, mask);
+	fs = fuse4fs_start(ff);
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	if (err || ino == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+
+	ret = check_inum_access(ff, ino, mask);
+	if (ret)
+		goto out;
+
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	ext2_ino_t parent, child;
+	char *temp_path;
+	errcode_t err;
+	char *node_name, a;
+	int filetype;
+	struct ext2_inode_large inode;
+	gid_t gid;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: path=%s mode=0%o\n", __func__, path, mode);
+	temp_path = strdup(path);
+	if (!temp_path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name = strrchr(temp_path, '/');
+	if (!node_name) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	node_name++;
+	a = *node_name;
+	*node_name = 0;
+
+	fs = fuse4fs_start(ff);
+	if (!fs_can_allocate(ff, 1)) {
+		ret = -ENOSPC;
+		goto out2;
+	}
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
+			   &parent);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out2;
+	}
+
+	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	if (ret)
+		goto out2;
+
+	err = fuse4fs_new_child_gid(ff, parent, &gid, NULL);
+	if (err)
+		goto out2;
+
+	*node_name = a;
+
+	filetype = ext2_file_type(mode);
+
+	err = ext2fs_new_inode(fs, parent, mode, 0, &child);
+	if (err) {
+		ret = translate_error(fs, parent, err);
+		goto out2;
+	}
+
+	dbg_printf(ff, "%s: creating ino=%d/name=%s in dir=%d\n", __func__, child,
+		   node_name, parent);
+	err = ext2fs_link(fs, parent, node_name, child,
+			  filetype | EXT2FS_LINK_EXPAND);
+	if (err) {
+		ret = translate_error(fs, parent, err);
+		goto out2;
+	}
+
+	ret = update_mtime(fs, parent, NULL);
+	if (ret)
+		goto out2;
+
+	memset(&inode, 0, sizeof(inode));
+	inode.i_mode = mode;
+	inode.i_links_count = 1;
+	fuse4fs_set_extra_isize(ff, child, &inode);
+	fuse4fs_set_uid(&inode, ctxt->uid);
+	fuse4fs_set_gid(&inode, gid);
+	if (ext2fs_has_feature_extents(fs->super)) {
+		ext2_extent_handle_t handle;
+
+		inode.i_flags &= ~EXT4_EXTENTS_FL;
+		ret = ext2fs_extent_open2(fs, child,
+					  EXT2_INODE(&inode), &handle);
+		if (ret) {
+			ret = translate_error(fs, child, err);
+			goto out2;
+		}
+
+		ext2fs_extent_free(handle);
+	}
+
+	err = ext2fs_write_new_inode(fs, child, EXT2_INODE(&inode));
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+
+	inode.i_generation = ff->next_generation++;
+	init_times(&inode);
+	err = fuse4fs_write_inode(fs, child, &inode);
+	if (err) {
+		ret = translate_error(fs, child, err);
+		goto out2;
+	}
+
+	ext2fs_inode_alloc_stats2(fs, child, 1, 0);
+
+	ret = propagate_default_acls(ff, parent, child, inode.i_mode);
+	if (ret)
+		goto out2;
+
+	fp->flags &= ~O_TRUNC;
+	ret = __op_open(ff, path, fp);
+	if (ret)
+		goto out2;
+
+	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+	if (ret)
+		goto out2;
+
+out2:
+	fuse4fs_finish(ff, ret);
+out:
+	free(temp_path);
+	return ret;
+}
+
+static int op_utimens(const char *path, const struct timespec ctv[2],
+		      struct fuse_file_info *fi)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	struct timespec tv[2];
+	ext2_filsys fs;
+	errcode_t err;
+	ext2_ino_t ino;
+	struct ext2_inode_large inode;
+	int access = W_OK;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	ret = fuse4fs_file_ino(ff, path, fi, &ino);
+	if (ret)
+		goto out;
+	dbg_printf(ff, "%s: ino=%d atime=%lld.%ld mtime=%lld.%ld\n", __func__,
+			ino,
+			(long long int)ctv[0].tv_sec, ctv[0].tv_nsec,
+			(long long int)ctv[1].tv_sec, ctv[1].tv_nsec);
+
+	/*
+	 * ext4 allows timestamp updates of append-only files but only if we're
+	 * setting to current time
+	 */
+	if (ctv[0].tv_nsec == UTIME_NOW && ctv[1].tv_nsec == UTIME_NOW)
+		access |= A_OK;
+	ret = check_inum_access(ff, ino, access);
+	if (ret)
+		goto out;
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+	tv[0] = ctv[0];
+	tv[1] = ctv[1];
+#ifdef UTIME_NOW
+	if (tv[0].tv_nsec == UTIME_NOW)
+		get_now(tv);
+	if (tv[1].tv_nsec == UTIME_NOW)
+		get_now(tv + 1);
+#endif /* UTIME_NOW */
+#ifdef UTIME_OMIT
+	if (tv[0].tv_nsec != UTIME_OMIT)
+		EXT4_INODE_SET_XTIME(i_atime, &tv[0], &inode);
+	if (tv[1].tv_nsec != UTIME_OMIT)
+		EXT4_INODE_SET_XTIME(i_mtime, &tv[1], &inode);
+#endif /* UTIME_OMIT */
+	ret = update_ctime(fs, ino, &inode);
+	if (ret)
+		goto out;
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+#define FUSE4FS_MODIFIABLE_IFLAGS \
+	(EXT2_FL_USER_MODIFIABLE & ~(EXT4_EXTENTS_FL | EXT4_CASEFOLD_FL | \
+				     EXT3_JOURNAL_DATA_FL))
+
+static inline int set_iflags(struct ext2_inode_large *inode, __u32 iflags)
+{
+	if ((inode->i_flags ^ iflags) & ~FUSE4FS_MODIFIABLE_IFLAGS)
+		return -EINVAL;
+
+	inode->i_flags = (inode->i_flags & ~FUSE4FS_MODIFIABLE_IFLAGS) |
+			 (iflags & FUSE4FS_MODIFIABLE_IFLAGS);
+	return 0;
+}
+
+#ifdef SUPPORT_I_FLAGS
+static int ioctl_getflags(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
+			  void *data)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	struct ext2_inode_large inode;
+
+	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	err = fuse4fs_read_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	*(__u32 *)data = inode.i_flags & EXT2_FL_USER_VISIBLE;
+	return 0;
+}
+
+static int ioctl_setflags(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
+			  void *data)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	struct ext2_inode_large inode;
+	int ret;
+	__u32 flags = *(__u32 *)data;
+	struct fuse_context *ctxt = fuse_get_context();
+
+	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	err = fuse4fs_read_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	if (want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
+		return -EPERM;
+
+	ret = set_iflags(&inode, flags);
+	if (ret)
+		return ret;
+
+	ret = update_ctime(fs, fh->ino, &inode);
+	if (ret)
+		return ret;
+
+	err = fuse4fs_write_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	return 0;
+}
+
+static int ioctl_getversion(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
+			    void *data)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	struct ext2_inode_large inode;
+
+	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	err = fuse4fs_read_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	*(__u32 *)data = inode.i_generation;
+	return 0;
+}
+
+static int ioctl_setversion(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
+			    void *data)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	struct ext2_inode_large inode;
+	int ret;
+	__u32 generation = *(__u32 *)data;
+	struct fuse_context *ctxt = fuse_get_context();
+
+	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	err = fuse4fs_read_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	if (want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
+		return -EPERM;
+
+	inode.i_generation = generation;
+
+	ret = update_ctime(fs, fh->ino, &inode);
+	if (ret)
+		return ret;
+
+	err = fuse4fs_write_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	return 0;
+}
+#endif /* SUPPORT_I_FLAGS */
+
+#ifdef FS_IOC_FSGETXATTR
+static __u32 iflags_to_fsxflags(__u32 iflags)
+{
+	__u32 xflags = 0;
+
+	if (iflags & FS_SYNC_FL)
+		xflags |= FS_XFLAG_SYNC;
+	if (iflags & FS_IMMUTABLE_FL)
+		xflags |= FS_XFLAG_IMMUTABLE;
+	if (iflags & FS_APPEND_FL)
+		xflags |= FS_XFLAG_APPEND;
+	if (iflags & FS_NODUMP_FL)
+		xflags |= FS_XFLAG_NODUMP;
+	if (iflags & FS_NOATIME_FL)
+		xflags |= FS_XFLAG_NOATIME;
+	if (iflags & FS_DAX_FL)
+		xflags |= FS_XFLAG_DAX;
+	if (iflags & FS_PROJINHERIT_FL)
+		xflags |= FS_XFLAG_PROJINHERIT;
+	return xflags;
+}
+
+static int ioctl_fsgetxattr(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
+			    void *data)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	struct ext2_inode_large inode;
+	struct fsxattr *fsx = data;
+	unsigned int inode_size;
+
+	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	err = fuse4fs_read_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	memset(fsx, 0, sizeof(*fsx));
+	inode_size = EXT2_GOOD_OLD_INODE_SIZE + inode.i_extra_isize;
+	if (ext2fs_inode_includes(inode_size, i_projid))
+		fsx->fsx_projid = inode_projid(inode);
+	fsx->fsx_xflags = iflags_to_fsxflags(inode.i_flags);
+	return 0;
+}
+
+static __u32 fsxflags_to_iflags(__u32 xflags)
+{
+	__u32 iflags = 0;
+
+	if (xflags & FS_XFLAG_IMMUTABLE)
+		iflags |= FS_IMMUTABLE_FL;
+	if (xflags & FS_XFLAG_APPEND)
+		iflags |= FS_APPEND_FL;
+	if (xflags & FS_XFLAG_SYNC)
+		iflags |= FS_SYNC_FL;
+	if (xflags & FS_XFLAG_NOATIME)
+		iflags |= FS_NOATIME_FL;
+	if (xflags & FS_XFLAG_NODUMP)
+		iflags |= FS_NODUMP_FL;
+	if (xflags & FS_XFLAG_DAX)
+		iflags |= FS_DAX_FL;
+	if (xflags & FS_XFLAG_PROJINHERIT)
+		iflags |= FS_PROJINHERIT_FL;
+	return iflags;
+}
+
+#define FUSE4FS_MODIFIABLE_XFLAGS (FS_XFLAG_IMMUTABLE | \
+				   FS_XFLAG_APPEND | \
+				   FS_XFLAG_SYNC | \
+				   FS_XFLAG_NOATIME | \
+				   FS_XFLAG_NODUMP | \
+				   FS_XFLAG_PROJINHERIT)
+
+#define FUSE4FS_MODIFIABLE_IXFLAGS (FS_IMMUTABLE_FL | \
+				    FS_APPEND_FL | \
+				    FS_SYNC_FL | \
+				    FS_NOATIME_FL | \
+				    FS_NODUMP_FL | \
+				    FS_PROJINHERIT_FL)
+
+static inline int set_xflags(struct ext2_inode_large *inode, __u32 xflags)
+{
+	__u32 iflags;
+
+	if (xflags & ~FUSE4FS_MODIFIABLE_XFLAGS)
+		return -EINVAL;
+
+	iflags = fsxflags_to_iflags(xflags);
+	inode->i_flags = (inode->i_flags & ~FUSE4FS_MODIFIABLE_IXFLAGS) |
+			 (iflags & FUSE4FS_MODIFIABLE_IXFLAGS);
+	return 0;
+}
+
+static int ioctl_fssetxattr(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
+			    void *data)
+{
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	struct ext2_inode_large inode;
+	int ret;
+	struct fuse_context *ctxt = fuse_get_context();
+	struct fsxattr *fsx = data;
+	unsigned int inode_size;
+
+	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	err = fuse4fs_read_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	if (want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
+		return -EPERM;
+
+	ret = set_xflags(&inode, fsx->fsx_xflags);
+	if (ret)
+		return ret;
+
+	inode_size = EXT2_GOOD_OLD_INODE_SIZE + inode.i_extra_isize;
+	if (ext2fs_inode_includes(inode_size, i_projid))
+		inode.i_projid = fsx->fsx_projid;
+
+	ret = update_ctime(fs, fh->ino, &inode);
+	if (ret)
+		return ret;
+
+	err = fuse4fs_write_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	return 0;
+}
+#endif /* FS_IOC_FSGETXATTR */
+
+#ifdef FITRIM
+static int ioctl_fitrim(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
+			void *data)
+{
+	ext2_filsys fs = ff->fs;
+	struct fstrim_range *fr = data;
+	blk64_t start, end, max_blocks, b, cleared, minlen;
+	blk64_t max_blks = ext2fs_blocks_count(fs->super);
+	errcode_t err = 0;
+
+	if (!fuse4fs_is_writeable(ff))
+		return -EROFS;
+
+	start = FUSE4FS_B_TO_FSBT(ff, fr->start);
+	if (fr->len == -1ULL)
+		end = -1ULL;
+	else
+		end = FUSE4FS_B_TO_FSBT(ff, fr->start + fr->len - 1);
+	minlen = FUSE4FS_B_TO_FSBT(ff, fr->minlen);
+
+	if (EXT2FS_NUM_B2C(fs, minlen) > EXT2_CLUSTERS_PER_GROUP(fs->super) ||
+	    start >= max_blks ||
+	    fr->len < fs->blocksize)
+		return -EINVAL;
+
+	dbg_printf(ff, "%s: start=0x%llx end=0x%llx minlen=0x%llx\n", __func__,
+		   start, end, minlen);
+
+	if (start < fs->super->s_first_data_block)
+		start = fs->super->s_first_data_block;
+
+	if (end < fs->super->s_first_data_block)
+		end = fs->super->s_first_data_block;
+	if (end >= ext2fs_blocks_count(fs->super))
+		end = ext2fs_blocks_count(fs->super) - 1;
+
+	cleared = 0;
+	max_blocks = FUSE4FS_B_TO_FSBT(ff, 2048ULL * 1024 * 1024);
+
+	fr->len = 0;
+	while (start <= end) {
+		err = ext2fs_find_first_zero_block_bitmap2(fs->block_map,
+							   start, end, &start);
+		switch (err) {
+		case 0:
+			break;
+		case ENOENT:
+			/* no free blocks found, so we're done */
+			err = 0;
+			goto out;
+		default:
+			return translate_error(fs, fh->ino, err);
+		}
+
+		b = start + max_blocks < end ? start + max_blocks : end;
+		err =  ext2fs_find_first_set_block_bitmap2(fs->block_map,
+							   start, b, &b);
+		switch (err) {
+		case 0:
+			break;
+		case ENOENT:
+			/*
+			 * No free blocks found between start and b; discard
+			 * the entire range.
+			 */
+			err = 0;
+			break;
+		default:
+			return translate_error(fs, fh->ino, err);
+		}
+
+		if (b - start >= minlen) {
+			err = io_channel_discard(fs->io, start, b - start);
+			if (err == EBUSY) {
+				/*
+				 * Apparently dm-thinp can return EBUSY when
+				 * it's too busy deallocating thinp units to
+				 * deallocate more.  Swallow these errors.
+				 */
+				err = 0;
+			}
+			if (err)
+				return translate_error(fs, fh->ino, err);
+			cleared += b - start;
+			fr->len = FUSE4FS_FSB_TO_B(ff, cleared);
+		}
+		start = b + 1;
+	}
+
+out:
+	fr->len = FUSE4FS_FSB_TO_B(ff, cleared);
+	dbg_printf(ff, "%s: len=%llu err=%ld\n", __func__, fr->len, err);
+	return err;
+}
+#endif /* FITRIM */
+
+#ifndef EXT4_IOC_SHUTDOWN
+# define EXT4_IOC_SHUTDOWN	_IOR('X', 125, __u32)
+#endif
+
+static int ioctl_shutdown(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
+			  void *data)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	ext2_filsys fs = ff->fs;
+
+	if (!is_superuser(ff, ctxt))
+		return -EPERM;
+
+	err_printf(ff, "%s.\n", _("shut down requested"));
+
+	/*
+	 * EXT4_IOC_SHUTDOWN inherited the inverted polarity on the ioctl
+	 * direction from XFS.  Unfortunately, that means we can't implement
+	 * any of the flags.  Flush whatever is dirty and shut down.
+	 */
+	if (ff->opstate == F4OP_WRITABLE)
+		ext2fs_flush2(fs, 0);
+	ff->opstate = F4OP_SHUTDOWN;
+
+	return 0;
+}
+
+static int op_ioctl(const char *path EXT2FS_ATTR((unused)),
+		    unsigned int cmd,
+		    void *arg EXT2FS_ATTR((unused)),
+		    struct fuse_file_info *fp,
+		    unsigned int flags EXT2FS_ATTR((unused)), void *data)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_HANDLE(ff, fh);
+	fuse4fs_start(ff);
+	switch ((unsigned long) cmd) {
+#ifdef SUPPORT_I_FLAGS
+	case EXT2_IOC_GETFLAGS:
+		ret = ioctl_getflags(ff, fh, data);
+		break;
+	case EXT2_IOC_SETFLAGS:
+		ret = ioctl_setflags(ff, fh, data);
+		break;
+	case EXT2_IOC_GETVERSION:
+		ret = ioctl_getversion(ff, fh, data);
+		break;
+	case EXT2_IOC_SETVERSION:
+		ret = ioctl_setversion(ff, fh, data);
+		break;
+#endif
+#ifdef FS_IOC_FSGETXATTR
+	case FS_IOC_FSGETXATTR:
+		ret = ioctl_fsgetxattr(ff, fh, data);
+		break;
+	case FS_IOC_FSSETXATTR:
+		ret = ioctl_fssetxattr(ff, fh, data);
+		break;
+#endif
+#ifdef FITRIM
+	case FITRIM:
+		ret = ioctl_fitrim(ff, fh, data);
+		break;
+#endif
+	case EXT4_IOC_SHUTDOWN:
+		ret = ioctl_shutdown(ff, fh, data);
+		break;
+	default:
+		dbg_printf(ff, "%s: Unknown ioctl %d\n", __func__, cmd);
+		ret = -ENOTTY;
+	}
+	fuse4fs_finish(ff, ret);
+
+	return ret;
+}
+
+static int op_bmap(const char *path, size_t blocksize EXT2FS_ATTR((unused)),
+		   uint64_t *idx)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	ext2_filsys fs;
+	ext2_ino_t ino;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	fs = fuse4fs_start(ff);
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+	dbg_printf(ff, "%s: ino=%d blk=%"PRIu64"\n", __func__, ino, *idx);
+
+	err = ext2fs_bmap2(fs, ino, NULL, NULL, 0, *idx, 0, (blk64_t *)idx);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out;
+	}
+
+out:
+	fuse4fs_finish(ff, ret);
+	return ret;
+}
+
+#ifdef SUPPORT_FALLOCATE
+static int fuse4fs_allocate_range(struct fuse4fs *ff,
+				  struct fuse4fs_file_handle *fh, int mode,
+				  off_t offset, off_t len)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_inode_large inode;
+	blk64_t start, end;
+	__u64 fsize;
+	errcode_t err;
+	int flags;
+
+	start = FUSE4FS_B_TO_FSBT(ff, offset);
+	end = FUSE4FS_B_TO_FSBT(ff, offset + len - 1);
+	dbg_printf(ff, "%s: ino=%d mode=0x%x offset=0x%llx len=0x%llx start=0x%llx end=0x%llx\n",
+		   __func__, fh->ino, mode,
+		   (unsigned long long)offset,
+		   (unsigned long long)len,
+		   (unsigned long long)start,
+		   (unsigned long long)end);
+	if (!fs_can_allocate(ff, FUSE4FS_B_TO_FSB(ff, len)))
+		return -ENOSPC;
+
+	err = fuse4fs_read_inode(fs, fh->ino, &inode);
+	if (err)
+		return err;
+	fsize = EXT2_I_SIZE(&inode);
+
+	/* Indirect files do not support unwritten extents */
+	if (!(inode.i_flags & EXT4_EXTENTS_FL))
+		return -EOPNOTSUPP;
+
+	/* Allocate a bunch of blocks */
+	flags = (mode & FL_KEEP_SIZE_FLAG ? 0 :
+			EXT2_FALLOCATE_INIT_BEYOND_EOF);
+	err = ext2fs_fallocate(fs, flags, fh->ino,
+			       EXT2_INODE(&inode),
+			       ~0ULL, start, end - start + 1);
+	if (err && err != EXT2_ET_BLOCK_ALLOC_FAIL)
+		return translate_error(fs, fh->ino, err);
+
+	/* Update i_size */
+	if (!(mode & FL_KEEP_SIZE_FLAG)) {
+		if ((__u64) offset + len > fsize) {
+			err = ext2fs_inode_size_set(fs,
+						EXT2_INODE(&inode),
+						offset + len);
+			if (err)
+				return translate_error(fs, fh->ino, err);
+		}
+	}
+
+	err = update_mtime(fs, fh->ino, &inode);
+	if (err)
+		return err;
+
+	err = fuse4fs_write_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	return err;
+}
+
+static errcode_t clean_block_middle(struct fuse4fs *ff, ext2_ino_t ino,
+				    struct ext2_inode_large *inode,
+				    off_t offset, off_t len, char **buf)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t blk;
+	off_t residue = FUSE4FS_OFF_IN_FSB(ff, offset);
+	int retflags;
+	errcode_t err;
+
+	if (!*buf) {
+		err = ext2fs_get_mem(fs->blocksize, buf);
+		if (err)
+			return err;
+	}
+
+	err = ext2fs_bmap2(fs, ino, EXT2_INODE(inode), *buf, 0,
+			   FUSE4FS_B_TO_FSBT(ff, offset), &retflags, &blk);
+	if (err)
+		return err;
+	if (!blk || (retflags & BMAP_RET_UNINIT))
+		return 0;
+
+	err = io_channel_read_blk64(fs->io, blk, 1, *buf);
+	if (err)
+		return err;
+
+	dbg_printf(ff, "%s: ino=%d offset=0x%llx len=0x%llx\n",
+		   __func__, ino,
+		   (unsigned long long)offset + residue,
+		   (unsigned long long)len);
+	memset(*buf + residue, 0, len);
+
+	return io_channel_write_blk64(fs->io, blk, 1, *buf);
+}
+
+static errcode_t clean_block_edge(struct fuse4fs *ff, ext2_ino_t ino,
+				  struct ext2_inode_large *inode, off_t offset,
+				  int clean_before, char **buf)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t blk;
+	int retflags;
+	off_t residue;
+	errcode_t err;
+
+	residue = FUSE4FS_OFF_IN_FSB(ff, offset);
+	if (residue == 0)
+		return 0;
+
+	if (!*buf) {
+		err = ext2fs_get_mem(fs->blocksize, buf);
+		if (err)
+			return err;
+	}
+
+	err = ext2fs_bmap2(fs, ino, EXT2_INODE(inode), *buf, 0,
+			   FUSE4FS_B_TO_FSBT(ff, offset), &retflags, &blk);
+	if (err)
+		return err;
+
+	err = io_channel_read_blk64(fs->io, blk, 1, *buf);
+	if (err)
+		return err;
+	if (!blk || (retflags & BMAP_RET_UNINIT))
+		return 0;
+
+	if (clean_before) {
+		dbg_printf(ff, "%s: ino=%d before offset=0x%llx len=0x%llx\n",
+			   __func__, ino,
+			   (unsigned long long)offset,
+			   (unsigned long long)residue);
+		memset(*buf, 0, residue);
+	} else {
+		dbg_printf(ff, "%s: ino=%d after offset=0x%llx len=0x%llx\n",
+			   __func__, ino,
+			   (unsigned long long)offset,
+			   (unsigned long long)fs->blocksize - residue);
+		memset(*buf + residue, 0, fs->blocksize - residue);
+	}
+
+	return io_channel_write_blk64(fs->io, blk, 1, *buf);
+}
+
+static int fuse4fs_punch_range(struct fuse4fs *ff,
+			       struct fuse4fs_file_handle *fh, int mode,
+			       off_t offset, off_t len)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_inode_large inode;
+	blk64_t start, end;
+	errcode_t err;
+	char *buf = NULL;
+
+	/* kernel ext4 punch requires this flag to be set */
+	if (!(mode & FL_KEEP_SIZE_FLAG))
+		return -EINVAL;
+
+	/*
+	 * Unmap out all full blocks in the middle of the range being punched.
+	 * The start of the unmap range should be the first byte of the first
+	 * fsblock that starts within the range.  The end of the range should
+	 * be the next byte after the last fsblock to end in the range.
+	 */
+	start = FUSE4FS_B_TO_FSBT(ff, round_up(offset, fs->blocksize));
+	end = FUSE4FS_B_TO_FSBT(ff, round_down(offset + len, fs->blocksize));
+
+	dbg_printf(ff,
+ "%s: ino=%d mode=0x%x offset=0x%llx len=0x%llx start=0x%llx end=0x%llx\n",
+		   __func__, fh->ino, mode,
+		   (unsigned long long)offset,
+		   (unsigned long long)len,
+		   (unsigned long long)start,
+		   (unsigned long long)end);
+
+	err = fuse4fs_read_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	/*
+	 * Indirect files do not support unwritten extents, which means we
+	 * can't support zero range.  Punch goes first in zero-range, which
+	 * is why the check is here.
+	 */
+	if ((mode & FL_ZERO_RANGE_FLAG) && !(inode.i_flags & EXT4_EXTENTS_FL))
+		return -EOPNOTSUPP;
+
+	/* Zero everything before the first block and after the last block */
+	if (FUSE4FS_B_TO_FSBT(ff, offset) == FUSE4FS_B_TO_FSBT(ff, offset + len))
+		err = clean_block_middle(ff, fh->ino, &inode, offset,
+					 len, &buf);
+	else {
+		err = clean_block_edge(ff, fh->ino, &inode, offset, 0, &buf);
+		if (!err)
+			err = clean_block_edge(ff, fh->ino, &inode,
+					       offset + len, 1, &buf);
+	}
+	if (buf)
+		ext2fs_free_mem(&buf);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	/*
+	 * Unmap full blocks in the middle, which is to say that start - end
+	 * must be at least one fsblock.  ext2fs_punch takes a closed interval
+	 * as its argument, so we pass [start, end - 1].
+	 */
+	if (start < end) {
+		err = ext2fs_punch(fs, fh->ino, EXT2_INODE(&inode),
+				   NULL, start, end - 1);
+		if (err)
+			return translate_error(fs, fh->ino, err);
+	}
+
+	err = update_mtime(fs, fh->ino, &inode);
+	if (err)
+		return err;
+
+	err = fuse4fs_write_inode(fs, fh->ino, &inode);
+	if (err)
+		return translate_error(fs, fh->ino, err);
+
+	return 0;
+}
+
+static int fuse4fs_zero_range(struct fuse4fs *ff,
+			      struct fuse4fs_file_handle *fh, int mode,
+			      off_t offset, off_t len)
+{
+	int ret = fuse4fs_punch_range(ff, fh, mode | FL_KEEP_SIZE_FLAG, offset,
+				      len);
+
+	if (!ret)
+		ret = fuse4fs_allocate_range(ff, fh, mode, offset, len);
+	return ret;
+}
+
+static int op_fallocate(const char *path EXT2FS_ATTR((unused)), int mode,
+			off_t offset, off_t len,
+			struct fuse_file_info *fp)
+{
+	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	int ret;
+
+	/* Catch unknown flags */
+	if (mode & ~(FL_ZERO_RANGE_FLAG | FL_PUNCH_HOLE_FLAG | FL_KEEP_SIZE_FLAG))
+		return -EOPNOTSUPP;
+
+	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_HANDLE(ff, fh);
+	fuse4fs_start(ff);
+	if (!fuse4fs_is_writeable(ff)) {
+		ret = -EROFS;
+		goto out;
+	}
+
+	dbg_printf(ff, "%s: ino=%d mode=0x%x start=0x%llx end=0x%llx\n", __func__,
+		   fh->ino, mode,
+		   (unsigned long long)offset,
+		   (unsigned long long)offset + len);
+
+	if (mode & FL_ZERO_RANGE_FLAG)
+		ret = fuse4fs_zero_range(ff, fh, mode, offset, len);
+	else if (mode & FL_PUNCH_HOLE_FLAG)
+		ret = fuse4fs_punch_range(ff, fh, mode, offset, len);
+	else
+		ret = fuse4fs_allocate_range(ff, fh, mode, offset, len);
+out:
+	fuse4fs_finish(ff, ret);
+
+	return ret;
+}
+#endif /* SUPPORT_FALLOCATE */
+
+static struct fuse_operations fs_ops = {
+	.init = op_init,
+	.destroy = op_destroy,
+	.getattr = op_getattr,
+	.readlink = op_readlink,
+	.mknod = op_mknod,
+	.mkdir = op_mkdir,
+	.unlink = op_unlink,
+	.rmdir = op_rmdir,
+	.symlink = op_symlink,
+	.rename = op_rename,
+	.link = op_link,
+	.chmod = op_chmod,
+	.chown = op_chown,
+	.truncate = op_truncate,
+	.open = op_open,
+	.read = op_read,
+	.write = op_write,
+	.statfs = op_statfs,
+	.release = op_release,
+	.fsync = op_fsync,
+	.setxattr = op_setxattr,
+	.getxattr = op_getxattr,
+	.listxattr = op_listxattr,
+	.removexattr = op_removexattr,
+	.opendir = op_open,
+	.readdir = op_readdir,
+	.releasedir = op_release,
+	.fsyncdir = op_fsync,
+	.access = op_access,
+	.create = op_create,
+	.utimens = op_utimens,
+	.bmap = op_bmap,
+#ifdef SUPERFLUOUS
+	.lock = op_lock,
+	.poll = op_poll,
+#endif
+	.ioctl = op_ioctl,
+#ifdef SUPPORT_FALLOCATE
+	.fallocate = op_fallocate,
+#endif
+};
+
+static int get_random_bytes(void *p, size_t sz)
+{
+	int fd;
+	ssize_t r;
+
+	fd = open("/dev/urandom", O_RDONLY);
+	if (fd < 0) {
+		perror("/dev/urandom");
+		return 0;
+	}
+
+	r = read(fd, p, sz);
+
+	close(fd);
+	return (size_t) r == sz;
+}
+
+enum {
+	FUSE4FS_IGNORED,
+	FUSE4FS_VERSION,
+	FUSE4FS_HELP,
+	FUSE4FS_HELPFULL,
+	FUSE4FS_CACHE_SIZE,
+	FUSE4FS_DIRSYNC,
+	FUSE4FS_ERRORS_BEHAVIOR,
+};
+
+#define FUSE4FS_OPT(t, p, v) { t, offsetof(struct fuse4fs, p), v }
+
+static struct fuse_opt fuse4fs_opts[] = {
+	FUSE4FS_OPT("ro",		ro,			1),
+	FUSE4FS_OPT("rw",		ro,			0),
+	FUSE4FS_OPT("minixdf",		minixdf,		1),
+	FUSE4FS_OPT("bsddf",		minixdf,		0),
+	FUSE4FS_OPT("fakeroot",		fakeroot,		1),
+	FUSE4FS_OPT("fuse4fs_debug",	debug,			1),
+	FUSE4FS_OPT("no_default_opts",	no_default_opts,	1),
+	FUSE4FS_OPT("norecovery",	norecovery,		1),
+	FUSE4FS_OPT("noload",		norecovery,		1),
+	FUSE4FS_OPT("offset=%lu",	offset,			0),
+	FUSE4FS_OPT("kernel",		kernel,			1),
+	FUSE4FS_OPT("directio",		directio,		1),
+	FUSE4FS_OPT("acl",		acl,			1),
+	FUSE4FS_OPT("noacl",		acl,			0),
+	FUSE4FS_OPT("lockfile=%s",	lockfile,		0),
+#ifdef HAVE_CLOCK_MONOTONIC
+	FUSE4FS_OPT("timing",		timing,			1),
+#endif
+	FUSE4FS_OPT("noblkdev",		noblkdev,		1),
+
+	FUSE_OPT_KEY("user_xattr",	FUSE4FS_IGNORED),
+	FUSE_OPT_KEY("noblock_validity", FUSE4FS_IGNORED),
+	FUSE_OPT_KEY("nodelalloc",	FUSE4FS_IGNORED),
+	FUSE_OPT_KEY("cache_size=%s",	FUSE4FS_CACHE_SIZE),
+	FUSE_OPT_KEY("dirsync",		FUSE4FS_DIRSYNC),
+	FUSE_OPT_KEY("errors=%s",	FUSE4FS_ERRORS_BEHAVIOR),
+
+	FUSE_OPT_KEY("-V",             FUSE4FS_VERSION),
+	FUSE_OPT_KEY("--version",      FUSE4FS_VERSION),
+	FUSE_OPT_KEY("-h",             FUSE4FS_HELP),
+	FUSE_OPT_KEY("--help",         FUSE4FS_HELP),
+	FUSE_OPT_KEY("--helpfull",     FUSE4FS_HELPFULL),
+	FUSE_OPT_END
+};
+
+
+static int fuse4fs_opt_proc(void *data, const char *arg,
+			    int key, struct fuse_args *outargs)
+{
+	struct fuse4fs *ff = data;
+
+	switch (key) {
+	case FUSE4FS_DIRSYNC:
+		ff->dirsync = 1;
+		/* pass through to libfuse */
+		return 1;
+	case FUSE_OPT_KEY_NONOPT:
+		if (!ff->device) {
+			ff->device = strdup(arg);
+			return 0;
+		}
+		return 1;
+	case FUSE4FS_CACHE_SIZE:
+		ff->cache_size = parse_num_blocks2(arg + 11, -1);
+		if (ff->cache_size < 1 || ff->cache_size > INT32_MAX) {
+			fprintf(stderr, "%s: %s\n", arg,
+ _("cache size must be between 1 block and 2GB."));
+			return -1;
+		}
+
+		/* do not pass through to libfuse */
+		return 0;
+	case FUSE4FS_ERRORS_BEHAVIOR:
+		if (strcmp(arg + 7, "continue") == 0)
+			ff->errors_behavior = EXT2_ERRORS_CONTINUE;
+		else if (strcmp(arg + 7, "remount-ro") == 0)
+			ff->errors_behavior = EXT2_ERRORS_RO;
+		else if (strcmp(arg + 7, "panic") == 0)
+			ff->errors_behavior = EXT2_ERRORS_PANIC;
+		else {
+			fprintf(stderr, "%s: %s\n", arg,
+ _("unknown errors behavior."));
+			return -1;
+		}
+
+		/* do not pass through to libfuse */
+		return 0;
+	case FUSE4FS_IGNORED:
+		return 0;
+	case FUSE4FS_HELP:
+	case FUSE4FS_HELPFULL:
+		fprintf(stderr,
+	"usage: %s device/image mountpoint [options]\n"
+	"\n"
+	"general options:\n"
+	"    -o opt,[opt...]  mount options\n"
+	"    -h   --help      print help\n"
+	"    -V   --version   print version\n"
+	"\n"
+	"fuse4fs options:\n"
+	"    -o errors=panic        dump core on error\n"
+	"    -o minixdf             minix-style df\n"
+	"    -o fakeroot            pretend to be root for permission checks\n"
+	"    -o no_default_opts     do not include default fuse options\n"
+	"    -o offset=<bytes>      similar to mount -o offset=<bytes>, mount the partition starting at <bytes>\n"
+	"    -o norecovery          don't replay the journal\n"
+	"    -o fuse4fs_debug       enable fuse4fs debugging\n"
+	"    -o lockfile=<file>     file to show that fuse is still using the file system image\n"
+	"    -o kernel              run this as if it were the kernel, which sets:\n"
+	"                           allow_others,default_permissions,suid,dev\n"
+	"    -o directio            use O_DIRECT to read and write the disk\n"
+	"    -o cache_size=N[KMG]   use a disk cache of this size\n"
+	"    -o errors=             behavior when an error is encountered:\n"
+	"                           continue|remount-ro|panic\n"
+	"\n",
+			outargs->argv[0]);
+		if (key == FUSE4FS_HELPFULL) {
+			fuse_opt_add_arg(outargs, "-h");
+			fuse_main(outargs->argc, outargs->argv, &fs_ops, NULL);
+		} else {
+			fprintf(stderr, "Try --helpfull to get a list of "
+				"all flags, including the FUSE options.\n");
+		}
+		exit(1);
+
+	case FUSE4FS_VERSION:
+		fprintf(stderr, "fuse4fs %s (%s)\n", E2FSPROGS_VERSION,
+			E2FSPROGS_DATE);
+		fuse_opt_add_arg(outargs, "--version");
+		fuse_main(outargs->argc, outargs->argv, &fs_ops, NULL);
+		exit(0);
+	}
+	return 1;
+}
+
+static const char *get_subtype(const char *argv0)
+{
+	size_t argvlen = strlen(argv0);
+
+	if (argvlen < 4)
+		goto out_default;
+
+	if (argv0[argvlen - 4] == 'e' &&
+	    argv0[argvlen - 3] == 'x' &&
+	    argv0[argvlen - 2] == 't' &&
+	    isdigit(argv0[argvlen - 1]))
+		return &argv0[argvlen - 4];
+
+out_default:
+	return "ext4";
+}
+
+/* Figure out a reasonable default size for the disk cache */
+static unsigned long long default_cache_size(void)
+{
+	long pages = 0, pagesize = 0;
+	unsigned long long max_cache;
+	unsigned long long ret = 32ULL << 20; /* 32 MB */
+
+#ifdef _SC_PHYS_PAGES
+	pages = sysconf(_SC_PHYS_PAGES);
+#endif
+#ifdef _SC_PAGESIZE
+	pagesize = sysconf(_SC_PAGESIZE);
+#endif
+	if (pages > 0 && pagesize > 0) {
+		max_cache = (unsigned long long)pagesize * pages / 20;
+
+		if (max_cache > 0 && ret > max_cache)
+			ret = max_cache;
+	}
+	return ret;
+}
+
+static inline bool fuse4fs_want_fuseblk(const struct fuse4fs *ff)
+{
+	if (ff->noblkdev)
+		return false;
+
+	/* libfuse won't let non-root do fuseblk mounts */
+	if (getuid() != 0)
+		return false;
+
+	return fuse4fs_on_bdev(ff);
+}
+
+static void fuse4fs_com_err_proc(const char *whoami, errcode_t code,
+				 const char *fmt, va_list args)
+{
+	fprintf(stderr, "FUSE4FS (%s): ", err_shortdev ? err_shortdev : "?");
+	if (whoami)
+		fprintf(stderr, "%s: ", whoami);
+	fprintf(stderr, "%s ", error_message(code));
+        vfprintf(stderr, fmt, args);
+	fprintf(stderr, "\n");
+	fflush(stderr);
+}
+
+int main(int argc, char *argv[])
+{
+	struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
+	struct fuse4fs fctx;
+	errcode_t err;
+	FILE *orig_stderr = stderr;
+	char extra_args[BUFSIZ];
+	int ret;
+
+	memset(&fctx, 0, sizeof(fctx));
+	fctx.magic = FUSE4FS_MAGIC;
+	fctx.logfd = -1;
+	fctx.opstate = F4OP_WRITABLE;
+
+	ret = fuse_opt_parse(&args, &fctx, fuse4fs_opts, fuse4fs_opt_proc);
+	if (ret)
+		exit(1);
+	if (fctx.device == NULL) {
+		fprintf(stderr, "Missing ext4 device/image\n");
+		fprintf(stderr, "See '%s -h' for usage\n", argv[0]);
+		exit(1);
+	}
+
+	/* /dev/sda -> sda for reporting */
+	fctx.shortdev = strrchr(fctx.device, '/');
+	if (fctx.shortdev)
+		fctx.shortdev++;
+	else
+		fctx.shortdev = fctx.device;
+
+	/* capture library error messages */
+	err_shortdev = fctx.shortdev;
+	set_com_err_hook(fuse4fs_com_err_proc);
+
+#ifdef ENABLE_NLS
+	setlocale(LC_MESSAGES, "");
+	setlocale(LC_CTYPE, "");
+	bindtextdomain(NLS_CAT_NAME, LOCALEDIR);
+	textdomain(NLS_CAT_NAME);
+	set_com_err_gettext(gettext);
+#endif
+	add_error_table(&et_ext2_error_table);
+
+	ret = fuse4fs_setup_logging(&fctx);
+	if (ret) {
+		/* operational error */
+		ret = 2;
+		goto out;
+	}
+
+#ifdef HAVE_PR_SET_IO_FLUSHER
+	/*
+	 * Register as a filesystem I/O server process so that our memory
+	 * allocations don't cause fs reclaim.
+	 */
+	ret = prctl(PR_GET_IO_FLUSHER, 0, 0, 0, 0);
+	if (ret == 0) {
+		ret = prctl(PR_SET_IO_FLUSHER, 1, 0, 0, 0);
+		if (ret < 0) {
+			err_printf(&fctx, "%s: %s.\n",
+ _("Could not register as IO flusher thread"),
+					strerror(errno));
+			ret = 0;
+		}
+	}
+#endif
+
+	/* Will we allow users to allocate every last block? */
+	if (getenv("FUSE4FS_ALLOC_ALL_BLOCKS")) {
+		log_printf(&fctx, "%s\n",
+ _("Allowing users to allocate all blocks. This is dangerous!"));
+		fctx.alloc_all_blocks = 1;
+	}
+
+	err = fuse4fs_open(&fctx, EXT2_FLAG_EXCLUSIVE);
+	if (err) {
+		ret = 32;
+		goto out;
+	}
+
+	if (fuse4fs_want_fuseblk(&fctx)) {
+		/*
+		 * If this is a block device, we want to close the fs, reopen
+		 * the block device in non-exclusive mode, and start the fuse
+		 * driver in fuseblk mode (which will reopen the block device
+		 * in exclusive mode) so that unmount will wait until
+		 * op_destroy completes.
+		 */
+		fuse4fs_unmount(&fctx);
+		err = fuse4fs_open(&fctx, 0);
+		if (err) {
+			ret = 32;
+			goto out;
+		}
+
+		/* "blkdev" is the magic mount option for fuseblk mode */
+		snprintf(extra_args, BUFSIZ, "-oblkdev,blksize=%u",
+			 fctx.fs->blocksize);
+		fuse_opt_add_arg(&args, extra_args);
+		fctx.unmount_in_destroy = 1;
+	}
+
+	if (!fctx.cache_size)
+		fctx.cache_size = default_cache_size();
+	if (fctx.cache_size) {
+		err = fuse4fs_config_cache(&fctx);
+		if (err) {
+			ret = 32;
+			goto out;
+		}
+	}
+
+	err = fuse4fs_check_support(&fctx);
+	if (err) {
+		ret = 32;
+		goto out;
+	}
+
+	/*
+	 * ext4 can't do COW of shared blocks, so if the feature is enabled,
+	 * we must force ro mode.
+	 */
+	if (ext2fs_has_feature_shared_blocks(fctx.fs->super))
+		fctx.ro = 1;
+
+	if (fctx.norecovery) {
+		ret = fuse4fs_check_norecovery(&fctx);
+		if (ret)
+			goto out;
+	}
+
+	err = fuse4fs_mount(&fctx);
+	if (err) {
+		ret = 32;
+		goto out;
+	}
+
+	/* Initialize generation counter */
+	get_random_bytes(&fctx.next_generation, sizeof(unsigned int));
+
+	/* Set up default fuse parameters */
+	snprintf(extra_args, BUFSIZ, "-okernel_cache,subtype=%s,"
+		 "fsname=%s,attr_timeout=0",
+		 get_subtype(argv[0]),
+		 fctx.device);
+	if (fctx.no_default_opts == 0)
+		fuse_opt_add_arg(&args, extra_args);
+
+	if (fctx.ro)
+		fuse_opt_add_arg(&args, "-oro");
+
+	if (fctx.fakeroot) {
+#ifdef HAVE_MOUNT_NODEV
+		fuse_opt_add_arg(&args,"-onodev");
+#endif
+#ifdef HAVE_MOUNT_NOSUID
+		fuse_opt_add_arg(&args,"-onosuid");
+#endif
+	}
+
+	if (fctx.kernel) {
+		/*
+		 * ACLs are always enforced when kernel mode is enabled, to
+		 * match the kernel ext4 driver which always enables ACLs.
+		 */
+		fctx.acl = 1;
+		fuse_opt_insert_arg(&args, 1,
+ "-oallow_other,default_permissions,suid,dev");
+	}
+
+	/*
+	 * Since there's a Big Kernel Lock around all the libext2fs code, we
+	 * only need to start four threads -- one to decode a request, another
+	 * to do the filesystem work, a third to transmit the reply, and a
+	 * fourth to handle fuse notifications.
+	 */
+	fuse_opt_insert_arg(&args, 1, "-omax_threads=4");
+
+	if (fctx.debug) {
+		int	i;
+
+		printf("FUSE4FS (%s): fuse arguments:", fctx.shortdev);
+		for (i = 0; i < args.argc; i++)
+			printf(" '%s'", args.argv[i]);
+		printf("\n");
+		fflush(stdout);
+	}
+
+	pthread_mutex_init(&fctx.bfl, NULL);
+	ret = fuse_main(args.argc, args.argv, &fs_ops, &fctx);
+	pthread_mutex_destroy(&fctx.bfl);
+
+	switch(ret) {
+	case 0:
+		/* success */
+		ret = 0;
+		break;
+	case 1:
+	case 2:
+		/* invalid option or no mountpoint */
+		ret = 1;
+		break;
+	case 3:
+	case 4:
+	case 5:
+	case 6:
+	case 7:
+		/* setup or mounting failed */
+		ret = 32;
+		break;
+	default:
+		/* fuse started up enough to call op_init */
+		ret = 0;
+		break;
+	}
+out:
+	if (ret & 1) {
+		fprintf(orig_stderr, "%s\n",
+ _("Mount failed due to unrecognized options.  Check dmesg(1) for details."));
+		fflush(orig_stderr);
+	}
+	if (ret & 32) {
+		fprintf(orig_stderr, "%s\n",
+ _("Mount failed while opening filesystem.  Check dmesg(1) for details."));
+		fflush(orig_stderr);
+	}
+	fuse4fs_unmount(&fctx);
+	reset_com_err_hook();
+	err_shortdev = NULL;
+	if (fctx.device)
+		free(fctx.device);
+	fuse_opt_free_args(&args);
+	return ret;
+}
+
+static int __translate_error(ext2_filsys fs, ext2_ino_t ino, errcode_t err,
+			     const char *func, int line)
+{
+	struct timespec now;
+	int ret = err;
+	struct fuse4fs *ff = fs->priv_data;
+	int is_err = 0;
+
+	/* Translate ext2 error to unix error code */
+	switch (err) {
+	case 0:
+		break;
+	case EXT2_ET_NO_MEMORY:
+	case EXT2_ET_TDB_ERR_OOM:
+		ret = -ENOMEM;
+		break;
+	case EXT2_ET_INVALID_ARGUMENT:
+	case EXT2_ET_LLSEEK_FAILED:
+		ret = -EINVAL;
+		break;
+	case EXT2_ET_NO_DIRECTORY:
+		ret = -ENOTDIR;
+		break;
+	case EXT2_ET_FILE_NOT_FOUND:
+		ret = -ENOENT;
+		break;
+	case EXT2_ET_DIR_NO_SPACE:
+		is_err = 1;
+		/* fallthrough */
+	case EXT2_ET_TOOSMALL:
+	case EXT2_ET_BLOCK_ALLOC_FAIL:
+	case EXT2_ET_INODE_ALLOC_FAIL:
+	case EXT2_ET_EA_NO_SPACE:
+		ret = -ENOSPC;
+		break;
+	case EXT2_ET_SYMLINK_LOOP:
+		ret = -EMLINK;
+		break;
+	case EXT2_ET_FILE_TOO_BIG:
+		ret = -EFBIG;
+		break;
+	case EXT2_ET_TDB_ERR_EXISTS:
+	case EXT2_ET_FILE_EXISTS:
+		ret = -EEXIST;
+		break;
+	case EXT2_ET_MMP_FAILED:
+	case EXT2_ET_MMP_FSCK_ON:
+		ret = -EBUSY;
+		break;
+	case EXT2_ET_EA_KEY_NOT_FOUND:
+		ret = -ENODATA;
+		break;
+	case EXT2_ET_UNIMPLEMENTED:
+		ret = -EOPNOTSUPP;
+		break;
+	case EXT2_ET_RO_FILSYS:
+		ret = -EROFS;
+		break;
+	case EXT2_ET_MAGIC_EXT2_FILE:
+	case EXT2_ET_MAGIC_EXT2FS_FILSYS:
+	case EXT2_ET_MAGIC_BADBLOCKS_LIST:
+	case EXT2_ET_MAGIC_BADBLOCKS_ITERATE:
+	case EXT2_ET_MAGIC_INODE_SCAN:
+	case EXT2_ET_MAGIC_IO_CHANNEL:
+	case EXT2_ET_MAGIC_UNIX_IO_CHANNEL:
+	case EXT2_ET_MAGIC_IO_MANAGER:
+	case EXT2_ET_MAGIC_BLOCK_BITMAP:
+	case EXT2_ET_MAGIC_INODE_BITMAP:
+	case EXT2_ET_MAGIC_GENERIC_BITMAP:
+	case EXT2_ET_MAGIC_TEST_IO_CHANNEL:
+	case EXT2_ET_MAGIC_DBLIST:
+	case EXT2_ET_MAGIC_ICOUNT:
+	case EXT2_ET_MAGIC_PQ_IO_CHANNEL:
+	case EXT2_ET_MAGIC_E2IMAGE:
+	case EXT2_ET_MAGIC_INODE_IO_CHANNEL:
+	case EXT2_ET_MAGIC_EXTENT_HANDLE:
+	case EXT2_ET_BAD_MAGIC:
+	case EXT2_ET_MAGIC_EXTENT_PATH:
+	case EXT2_ET_MAGIC_GENERIC_BITMAP64:
+	case EXT2_ET_MAGIC_BLOCK_BITMAP64:
+	case EXT2_ET_MAGIC_INODE_BITMAP64:
+	case EXT2_ET_MAGIC_RESERVED_13:
+	case EXT2_ET_MAGIC_RESERVED_14:
+	case EXT2_ET_MAGIC_RESERVED_15:
+	case EXT2_ET_MAGIC_RESERVED_16:
+	case EXT2_ET_MAGIC_RESERVED_17:
+	case EXT2_ET_MAGIC_RESERVED_18:
+	case EXT2_ET_MAGIC_RESERVED_19:
+	case EXT2_ET_MMP_MAGIC_INVALID:
+	case EXT2_ET_MAGIC_EA_HANDLE:
+	case EXT2_ET_DIR_CORRUPTED:
+	case EXT2_ET_CORRUPT_SUPERBLOCK:
+	case EXT2_ET_RESIZE_INODE_CORRUPT:
+	case EXT2_ET_TDB_ERR_CORRUPT:
+	case EXT2_ET_UNDO_FILE_CORRUPT:
+	case EXT2_ET_FILESYSTEM_CORRUPTED:
+	case EXT2_ET_CORRUPT_JOURNAL_SB:
+	case EXT2_ET_INODE_CORRUPTED:
+	case EXT2_ET_EA_INODE_CORRUPTED:
+		/* same errno that linux uses */
+		is_err = 1;
+		ret = -EUCLEAN;
+		break;
+	case EIO:
+#ifdef EILSEQ
+	case EILSEQ:
+#endif
+	case EUCLEAN:
+		/* these errnos usually denote corruption or persistence fail */
+		is_err = 1;
+		ret = -err;
+		break;
+	default:
+		if (err < 256) {
+			/* other errno are usually operational errors */
+			ret = -err;
+		} else {
+			is_err = 1;
+			ret = -EIO;
+		}
+		break;
+	}
+
+	if (!is_err)
+		return ret;
+
+	if (ino)
+		err_printf(ff, "%s (inode #%d) at %s:%d.\n",
+			error_message(err), ino, func, line);
+	else
+		err_printf(ff, "%s at %s:%d.\n",
+			error_message(err), func, line);
+
+	/* Make a note in the error log */
+	get_now(&now);
+	ext2fs_set_tstamp(fs->super, s_last_error_time, now.tv_sec);
+	fs->super->s_last_error_ino = ino;
+	fs->super->s_last_error_line = line;
+	fs->super->s_last_error_block = err; /* Yeah... */
+	strncpy((char *)fs->super->s_last_error_func, func,
+		sizeof(fs->super->s_last_error_func));
+	if (ext2fs_get_tstamp(fs->super, s_first_error_time) == 0) {
+		ext2fs_set_tstamp(fs->super, s_first_error_time, now.tv_sec);
+		fs->super->s_first_error_ino = ino;
+		fs->super->s_first_error_line = line;
+		fs->super->s_first_error_block = err;
+		strncpy((char *)fs->super->s_first_error_func, func,
+			sizeof(fs->super->s_first_error_func));
+	}
+
+	fs->super->s_state |= EXT2_ERROR_FS;
+	fs->super->s_error_count++;
+	ext2fs_mark_super_dirty(fs);
+	ext2fs_flush(fs);
+	switch (ff->errors_behavior) {
+	case EXT2_ERRORS_CONTINUE:
+		err_printf(ff, "%s\n",
+ _("Continuing after errors; is this a good idea?"));
+		break;
+	case EXT2_ERRORS_RO:
+		if (ff->opstate == F4OP_WRITABLE) {
+			err_printf(ff, "%s\n",
+ _("Remounting read-only due to errors."));
+			ff->opstate = F4OP_READONLY;
+		}
+		fs->flags &= ~EXT2_FLAG_RW;
+		break;
+	case EXT2_ERRORS_PANIC:
+		err_printf(ff, "%s\n",
+ _("Aborting filesystem mount due to errors."));
+		abort();
+		break;
+	}
+
+	return ret;
+}
diff --git a/lib/config.h.in b/lib/config.h.in
index a4d8ce1c3765ed..c3379758c3c9bc 100644
--- a/lib/config.h.in
+++ b/lib/config.h.in
@@ -73,6 +73,9 @@
 /* Define to 1 if PR_SET_IO_FLUSHER is present */
 #undef HAVE_PR_SET_IO_FLUSHER
 
+/* Define to 1 if fuse supports lowlevel API */
+#undef HAVE_FUSE_LOWLEVEL
+
 /* Define to 1 if you have the Mac OS X function
    CFLocaleCopyPreferredLanguages in the CoreFoundation framework. */
 #undef HAVE_CFLOCALECOPYPREFERREDLANGUAGES

[PATCH 03/21] debian: create new package for fuse4fs

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create a new package for fuse4fs.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 debian/control         |   12 +++++++++++-
 debian/fuse4fs.install |    2 ++
 debian/rules           |   11 +++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 debian/fuse4fs.install


diff --git a/debian/control b/debian/control
index fb3487cd32b99a..94c6b82e25a97e 100644
--- a/debian/control
+++ b/debian/control
@@ -2,7 +2,7 @@ Source: e2fsprogs
 Section: admin
 Priority: important
 Maintainer: Theodore Y. Ts'o <tytso@mit.edu>
-Build-Depends: dpkg-dev (>= 1.22.5), gettext, texinfo, pkgconf, libarchive-dev <!nocheck>, libfuse3-dev [linux-any kfreebsd-any] <!pkg.e2fsprogs.no-fuse2fs>, debhelper-compat (= 12), dh-exec, libblkid-dev, uuid-dev, m4, udev [linux-any], systemd [linux-any], systemd-dev [linux-any], cron [linux-any], dh-sequence-movetousr
+Build-Depends: dpkg-dev (>= 1.22.5), gettext, texinfo, pkgconf, libarchive-dev <!nocheck>, libfuse3-dev [linux-any kfreebsd-any] <!pkg.e2fsprogs.no-fuse2fs> <!pkg.e2fsprogs.no-fuse4fs>, debhelper-compat (= 12), dh-exec, libblkid-dev, uuid-dev, m4, udev [linux-any], systemd [linux-any], systemd-dev [linux-any], cron [linux-any], dh-sequence-movetousr
 Rules-Requires-Root: no
 Standards-Version: 4.7.2
 Homepage: http://e2fsprogs.sourceforge.net
@@ -21,6 +21,16 @@ Description: ext2 / ext3 / ext4 file system driver for FUSE
  writing from devices or image files containing ext2, ext3, and ext4
  file systems.
 
+Package: fuse4fs
+Build-Profiles: <!pkg.e2fsprogs.no-fuse4fs>
+Priority: optional
+Depends: ${shlibs:Depends}, ${misc:Depends}
+Architecture: linux-any kfreebsd-any
+Description: ext2 / ext3 / ext4 file system driver for FUSE
+ fuse4fs is a faster FUSE file system client that supports reading and
+ writing from devices or image files containing ext2, ext3, and ext4
+ file systems.
+
 Package: fuseext2
 Build-Profiles: <!pkg.e2fsprogs.no-fuse2fs>
 Depends: fuse2fs (>= 1.47.1-2), ${misc:Depends}
diff --git a/debian/fuse4fs.install b/debian/fuse4fs.install
new file mode 100644
index 00000000000000..fb8c8ab671c73c
--- /dev/null
+++ b/debian/fuse4fs.install
@@ -0,0 +1,2 @@
+/usr/bin/fuse4fs
+/usr/share/man/man1/fuse4fs.1
diff --git a/debian/rules b/debian/rules
index 4cb80652115317..3240d6bc2640c9 100755
--- a/debian/rules
+++ b/debian/rules
@@ -12,6 +12,7 @@ export LC_ALL ?= C
 
 ifeq ($(DEB_HOST_ARCH_OS), hurd)
 SKIP_FUSE2FS=yes
+SKIP_FUSE4FS=yes
 endif
 
 ifeq ($(DEB_HOST_ARCH_OS), linux)
@@ -22,6 +23,9 @@ endif
 ifneq ($(filter pkg.e2fsprogs.no-fuse2fs,$(DEB_BUILD_PROFILES)),)
 SKIP_FUSE2FS=yes
 endif
+ifneq ($(filter pkg.e2fsprogs.no-fuse4fs,$(DEB_BUILD_PROFILES)),)
+SKIP_FUSE4FS=yes
+endif
 
 ifneq (,$(filter-out parallel=1,$(filter parallel=%,$(DEB_BUILD_OPTIONS))))
     NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
@@ -60,6 +64,9 @@ COMMON_CONF_FLAGS = --enable-elf-shlibs --disable-ubsan \
 ifneq ($(SKIP_FUSE2FS),)
 COMMON_CONF_FLAGS +=  --disable-fuse2fs
 endif
+ifneq ($(SKIP_FUSE4FS),)
+COMMON_CONF_FLAGS +=  --disable-fuse4fs
+endif
 
 ifneq ($(DEB_BUILD_GNU_TYPE),$(DEB_HOST_GNU_TYPE))
 CC ?= $(DEB_HOST_GNU_TYPE)-gcc
@@ -189,6 +196,10 @@ endif
 ifeq ($(SKIP_FUSE2FS),)
 	dh_shlibdeps -pfuse2fs -l${stdbuilddir}/lib \
 		-- -Ldebian/e2fsprogs.shlibs.local
+endif
+ifeq ($(SKIP_FUSE4FS),)
+	dh_shlibdeps -pfuse4fs -l${stdbuilddir}/lib \
+		-- -Ldebian/e2fsprogs.shlibs.local
 endif
 	dh_shlibdeps --remaining-packages -l${stdbuilddir}/lib
 

[PATCH 04/21] fuse4fs: namespace some helpers

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Prepend "fuse4fs_" to all helper functions that take a struct fuse4fs
object pointer.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |  177 +++++++++++++++++++++++++++--------------------------
 1 file changed, 90 insertions(+), 87 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 99b9b902b37a57..a4eeb86201db0c 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -2,6 +2,7 @@
  * fuse4fs.c - FUSE low-level server for e2fsprogs.
  *
  * Copyright (C) 2014-2025 Oracle.
+ * Copyright (C) 2025 CTERA Networks.
  *
  * %Begin-Header%
  * This file may be redistributed under the terms of the GNU Public
@@ -696,7 +697,7 @@ static int ext2_file_type(unsigned int mode)
 	return 0;
 }
 
-static int fs_can_allocate(struct fuse4fs *ff, blk64_t num)
+static int fuse4fs_can_allocate(struct fuse4fs *ff, blk64_t num)
 {
 	ext2_filsys fs = ff->fs;
 	blk64_t reserved;
@@ -723,21 +724,22 @@ static int fs_can_allocate(struct fuse4fs *ff, blk64_t num)
 	return ext2fs_free_blocks_count(fs->super) > reserved + num;
 }
 
-static int fuse4fs_is_writeable(struct fuse4fs *ff)
+static int fuse4fs_is_writeable(const struct fuse4fs *ff)
 {
 	return ff->opstate == F4OP_WRITABLE &&
 		(ff->fs->super->s_error_count == 0);
 }
 
-static inline int is_superuser(struct fuse4fs *ff, struct fuse_context *ctxt)
+static inline int fuse4fs_is_superuser(struct fuse4fs *ff,
+				       const struct fuse_context *ctxt)
 {
 	if (ff->fakeroot)
 		return 1;
 	return ctxt->uid == 0;
 }
 
-static inline int want_check_owner(struct fuse4fs *ff,
-				   struct fuse_context *ctxt)
+static inline int fuse4fs_want_check_owner(struct fuse4fs *ff,
+					   const struct fuse_context *ctxt)
 {
 	/*
 	 * The kernel is responsible for access control, so we allow anything
@@ -745,14 +747,14 @@ static inline int want_check_owner(struct fuse4fs *ff,
 	 */
 	if (ff->kernel)
 		return 0;
-	return !is_superuser(ff, ctxt);
+	return !fuse4fs_is_superuser(ff, ctxt);
 }
 
 /* Test for append permission */
 #define A_OK	16
 
-static int check_iflags_access(struct fuse4fs *ff, ext2_ino_t ino,
-			       const struct ext2_inode *inode, int mask)
+static int fuse4fs_iflags_access(struct fuse4fs *ff, ext2_ino_t ino,
+				 const struct ext2_inode *inode, int mask)
 {
 	EXT2FS_BUILD_BUG_ON((A_OK & (R_OK | W_OK | X_OK | F_OK)) != 0);
 
@@ -780,7 +782,7 @@ static int check_iflags_access(struct fuse4fs *ff, ext2_ino_t ino,
 	return 0;
 }
 
-static int check_inum_access(struct fuse4fs *ff, ext2_ino_t ino, int mask)
+static int fuse4fs_inum_access(struct fuse4fs *ff, ext2_ino_t ino, int mask)
 {
 	struct fuse_context *ctxt = fuse_get_context();
 	ext2_filsys fs = ff->fs;
@@ -812,7 +814,7 @@ static int check_inum_access(struct fuse4fs *ff, ext2_ino_t ino, int mask)
 	if (mask == 0)
 		return 0;
 
-	ret = check_iflags_access(ff, ino, &inode, mask);
+	ret = fuse4fs_iflags_access(ff, ino, &inode, mask);
 	if (ret)
 		return ret;
 
@@ -821,7 +823,7 @@ static int check_inum_access(struct fuse4fs *ff, ext2_ino_t ino, int mask)
 		return 0;
 
 	/* Figure out what root's allowed to do */
-	if (is_superuser(ff, ctxt)) {
+	if (fuse4fs_is_superuser(ff, ctxt)) {
 		/* Non-file access always ok */
 		if (!LINUX_S_ISREG(inode.i_mode))
 			return 0;
@@ -1539,8 +1541,8 @@ static int op_readlink(const char *path, char *buf, size_t len)
 	return ret;
 }
 
-static int __getxattr(struct fuse4fs *ff, ext2_ino_t ino, const char *name,
-		      void **value, size_t *value_len)
+static int fuse4fs_getxattr(struct fuse4fs *ff, ext2_ino_t ino,
+			    const char *name, void **value, size_t *value_len)
 {
 	ext2_filsys fs = ff->fs;
 	struct ext2_xattr_handle *h;
@@ -1570,8 +1572,8 @@ static int __getxattr(struct fuse4fs *ff, ext2_ino_t ino, const char *name,
 	return ret;
 }
 
-static int __setxattr(struct fuse4fs *ff, ext2_ino_t ino, const char *name,
-		      void *value, size_t valuelen)
+static int fuse4fs_setxattr(struct fuse4fs *ff, ext2_ino_t ino,
+			    const char *name, void *value, size_t valuelen)
 {
 	ext2_filsys fs = ff->fs;
 	struct ext2_xattr_handle *h;
@@ -1601,8 +1603,8 @@ static int __setxattr(struct fuse4fs *ff, ext2_ino_t ino, const char *name,
 	return ret;
 }
 
-static int propagate_default_acls(struct fuse4fs *ff, ext2_ino_t parent,
-				  ext2_ino_t child, mode_t mode)
+static int fuse4fs_propagate_default_acls(struct fuse4fs *ff, ext2_ino_t parent,
+					  ext2_ino_t child, mode_t mode)
 {
 	void *def;
 	size_t deflen;
@@ -1611,8 +1613,8 @@ static int propagate_default_acls(struct fuse4fs *ff, ext2_ino_t parent,
 	if (!ff->acl || S_ISDIR(mode))
 		return 0;
 
-	ret = __getxattr(ff, parent, XATTR_NAME_POSIX_ACL_DEFAULT, &def,
-			 &deflen);
+	ret = fuse4fs_getxattr(ff, parent, XATTR_NAME_POSIX_ACL_DEFAULT, &def,
+			       &deflen);
 	switch (ret) {
 	case -ENODATA:
 	case -ENOENT:
@@ -1624,7 +1626,8 @@ static int propagate_default_acls(struct fuse4fs *ff, ext2_ino_t parent,
 		return ret;
 	}
 
-	ret = __setxattr(ff, child, XATTR_NAME_POSIX_ACL_DEFAULT, def, deflen);
+	ret = fuse4fs_setxattr(ff, child, XATTR_NAME_POSIX_ACL_DEFAULT, def,
+			       deflen);
 	ext2fs_free_mem(&def);
 	return ret;
 }
@@ -1753,7 +1756,7 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
 	*node_name = 0;
 
 	fs = fuse4fs_start(ff);
-	if (!fs_can_allocate(ff, 2)) {
+	if (!fuse4fs_can_allocate(ff, 2)) {
 		ret = -ENOSPC;
 		goto out2;
 	}
@@ -1765,7 +1768,7 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
 		goto out2;
 	}
 
-	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
@@ -1835,7 +1838,7 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
 
 	ext2fs_inode_alloc_stats2(fs, child, 1, 0);
 
-	ret = propagate_default_acls(ff, parent, child, inode.i_mode);
+	ret = fuse4fs_propagate_default_acls(ff, parent, child, inode.i_mode);
 	if (ret)
 		goto out2;
 
@@ -1883,7 +1886,7 @@ static int op_mkdir(const char *path, mode_t mode)
 	*node_name = 0;
 
 	fs = fuse4fs_start(ff);
-	if (!fs_can_allocate(ff, 1)) {
+	if (!fuse4fs_can_allocate(ff, 1)) {
 		ret = -ENOSPC;
 		goto out2;
 	}
@@ -1895,7 +1898,7 @@ static int op_mkdir(const char *path, mode_t mode)
 		goto out2;
 	}
 
-	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
@@ -1968,7 +1971,7 @@ static int op_mkdir(const char *path, mode_t mode)
 		goto out3;
 	}
 
-	ret = propagate_default_acls(ff, parent, child, inode.i_mode);
+	ret = fuse4fs_propagate_default_acls(ff, parent, child, inode.i_mode);
 	if (ret)
 		goto out3;
 
@@ -2009,7 +2012,7 @@ static int fuse4fs_unlink(struct fuse4fs *ff, const char *path,
 		base_name = filename;
 	}
 
-	ret = check_inum_access(ff, dir, W_OK);
+	ret = fuse4fs_inum_access(ff, dir, W_OK);
 	if (ret) {
 		free(filename);
 		return ret;
@@ -2031,8 +2034,8 @@ static int fuse4fs_unlink(struct fuse4fs *ff, const char *path,
 	return 0;
 }
 
-static int remove_ea_inodes(struct fuse4fs *ff, ext2_ino_t ino,
-			    struct ext2_inode_large *inode)
+static int fuse4fs_remove_ea_inodes(struct fuse4fs *ff, ext2_ino_t ino,
+				    struct ext2_inode_large *inode)
 {
 	ext2_filsys fs = ff->fs;
 	struct ext2_xattr_handle *h;
@@ -2076,7 +2079,7 @@ static int remove_ea_inodes(struct fuse4fs *ff, ext2_ino_t ino,
 	return 0;
 }
 
-static int remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
+static int fuse4fs_remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
@@ -2109,7 +2112,7 @@ static int remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 		goto write_out;
 
 	if (ext2fs_has_feature_ea_inode(fs->super)) {
-		ret = remove_ea_inodes(ff, ino, &inode);
+		ret = fuse4fs_remove_ea_inodes(ff, ino, &inode);
 		if (ret)
 			return ret;
 	}
@@ -2150,7 +2153,7 @@ static int __op_unlink(struct fuse4fs *ff, const char *path)
 		goto out;
 	}
 
-	ret = check_inum_access(ff, ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ino, W_OK);
 	if (ret)
 		goto out;
 
@@ -2158,7 +2161,7 @@ static int __op_unlink(struct fuse4fs *ff, const char *path)
 	if (ret)
 		goto out;
 
-	ret = remove_inode(ff, ino);
+	ret = fuse4fs_remove_inode(ff, ino);
 	if (ret)
 		goto out;
 
@@ -2226,7 +2229,7 @@ static int __op_rmdir(struct fuse4fs *ff, const char *path)
 	}
 	dbg_printf(ff, "%s: rmdir path=%s ino=%d\n", __func__, path, child);
 
-	ret = check_inum_access(ff, child, W_OK);
+	ret = fuse4fs_inum_access(ff, child, W_OK);
 	if (ret)
 		goto out;
 
@@ -2245,7 +2248,7 @@ static int __op_rmdir(struct fuse4fs *ff, const char *path)
 		goto out;
 	}
 
-	ret = check_inum_access(ff, rds.parent, W_OK);
+	ret = fuse4fs_inum_access(ff, rds.parent, W_OK);
 	if (ret)
 		goto out;
 
@@ -2258,10 +2261,10 @@ static int __op_rmdir(struct fuse4fs *ff, const char *path)
 	if (ret)
 		goto out;
 	/* Directories have to be "removed" twice. */
-	ret = remove_inode(ff, child);
+	ret = fuse4fs_remove_inode(ff, child);
 	if (ret)
 		goto out;
-	ret = remove_inode(ff, child);
+	ret = fuse4fs_remove_inode(ff, child);
 	if (ret)
 		goto out;
 
@@ -2347,7 +2350,7 @@ static int op_symlink(const char *src, const char *dest)
 		goto out2;
 	}
 
-	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
@@ -2459,7 +2462,7 @@ static int op_rename(const char *from, const char *to,
 	FUSE4FS_CHECK_CONTEXT(ff);
 	dbg_printf(ff, "%s: renaming %s to %s\n", __func__, from, to);
 	fs = fuse4fs_start(ff);
-	if (!fs_can_allocate(ff, 5)) {
+	if (!fuse4fs_can_allocate(ff, 5)) {
 		ret = -ENOSPC;
 		goto out;
 	}
@@ -2485,12 +2488,12 @@ static int op_rename(const char *from, const char *to,
 		goto out;
 	}
 
-	ret = check_inum_access(ff, from_ino, W_OK);
+	ret = fuse4fs_inum_access(ff, from_ino, W_OK);
 	if (ret)
 		goto out;
 
 	if (to_ino) {
-		ret = check_inum_access(ff, to_ino, W_OK);
+		ret = fuse4fs_inum_access(ff, to_ino, W_OK);
 		if (ret)
 			goto out;
 	}
@@ -2528,7 +2531,7 @@ static int op_rename(const char *from, const char *to,
 		goto out2;
 	}
 
-	ret = check_inum_access(ff, from_dir_ino, W_OK);
+	ret = fuse4fs_inum_access(ff, from_dir_ino, W_OK);
 	if (ret)
 		goto out2;
 
@@ -2553,7 +2556,7 @@ static int op_rename(const char *from, const char *to,
 		goto out2;
 	}
 
-	ret = check_inum_access(ff, to_dir_ino, W_OK);
+	ret = fuse4fs_inum_access(ff, to_dir_ino, W_OK);
 	if (ret)
 		goto out2;
 
@@ -2700,7 +2703,7 @@ static int op_link(const char *src, const char *dest)
 	*node_name = 0;
 
 	fs = fuse4fs_start(ff);
-	if (!fs_can_allocate(ff, 2)) {
+	if (!fuse4fs_can_allocate(ff, 2)) {
 		ret = -ENOSPC;
 		goto out2;
 	}
@@ -2713,7 +2716,7 @@ static int op_link(const char *src, const char *dest)
 		goto out2;
 	}
 
-	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
@@ -2729,7 +2732,7 @@ static int op_link(const char *src, const char *dest)
 		goto out2;
 	}
 
-	ret = check_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	ret = fuse4fs_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
 	if (ret)
 		goto out2;
 
@@ -2769,7 +2772,7 @@ static int op_link(const char *src, const char *dest)
 }
 
 /* Obtain group ids of the process that sent us a command(?) */
-static int get_req_groups(struct fuse4fs *ff, gid_t **gids, size_t *nr_gids)
+static int fuse4fs_get_groups(struct fuse4fs *ff, gid_t **gids, size_t *nr_gids)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
@@ -2814,8 +2817,8 @@ static int get_req_groups(struct fuse4fs *ff, gid_t **gids, size_t *nr_gids)
  * that initiated the fuse request?  Returns 1 for yes, 0 for no, or a negative
  * errno.
  */
-static int in_file_group(struct fuse_context *ctxt,
-			 const struct ext2_inode_large *inode)
+static int fuse4fs_in_file_group(struct fuse_context *ctxt,
+				 const struct ext2_inode_large *inode)
 {
 	struct fuse4fs *ff = fuse4fs_get();
 	gid_t *gids = NULL;
@@ -2827,7 +2830,7 @@ static int in_file_group(struct fuse_context *ctxt,
 	if (ctxt->gid == gid)
 		return 1;
 
-	ret = get_req_groups(ff, &gids, &nr_gids);
+	ret = fuse4fs_get_groups(ff, &gids, &nr_gids);
 	if (ret == -ENOENT) {
 		/* magic return code for "could not get caller group info" */
 		return 0;
@@ -2870,11 +2873,11 @@ static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
 		goto out;
 	}
 
-	ret = check_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	ret = fuse4fs_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
 	if (ret)
 		goto out;
 
-	if (want_check_owner(ff, ctxt) && ctxt->uid != inode_uid(inode)) {
+	if (fuse4fs_want_check_owner(ff, ctxt) && ctxt->uid != inode_uid(inode)) {
 		ret = -EPERM;
 		goto out;
 	}
@@ -2884,8 +2887,8 @@ static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
 	 * of the user's groups, but FUSE only tells us about the primary
 	 * group.
 	 */
-	if (!is_superuser(ff, ctxt)) {
-		ret = in_file_group(ctxt, &inode);
+	if (!fuse4fs_is_superuser(ff, ctxt)) {
+		ret = fuse4fs_in_file_group(ctxt, &inode);
 		if (ret < 0)
 			goto out;
 
@@ -2939,14 +2942,14 @@ static int op_chown(const char *path, uid_t owner, gid_t group,
 		goto out;
 	}
 
-	ret = check_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	ret = fuse4fs_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
 	if (ret)
 		goto out;
 
 	/* FUSE seems to feed us ~0 to mean "don't change" */
 	if (owner != (uid_t) ~0) {
 		/* Only root gets to change UID. */
-		if (want_check_owner(ff, ctxt) &&
+		if (fuse4fs_want_check_owner(ff, ctxt) &&
 		    !(inode_uid(inode) == ctxt->uid && owner == ctxt->uid)) {
 			ret = -EPERM;
 			goto out;
@@ -2956,7 +2959,7 @@ static int op_chown(const char *path, uid_t owner, gid_t group,
 
 	if (group != (gid_t) ~0) {
 		/* Only root or the owner get to change GID. */
-		if (want_check_owner(ff, ctxt) &&
+		if (fuse4fs_want_check_owner(ff, ctxt) &&
 		    inode_uid(inode) != ctxt->uid) {
 			ret = -EPERM;
 			goto out;
@@ -3066,7 +3069,7 @@ static int op_truncate(const char *path, off_t len, struct fuse_file_info *fi)
 		goto out;
 	dbg_printf(ff, "%s: ino=%d len=%jd\n", __func__, ino, (intmax_t) len);
 
-	ret = check_inum_access(ff, ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ino, W_OK);
 	if (ret)
 		goto out;
 
@@ -3148,7 +3151,7 @@ static int __op_open(struct fuse4fs *ff, const char *path,
 	}
 	dbg_printf(ff, "%s: ino=%d\n", __func__, file->ino);
 
-	ret = check_inum_access(ff, file->ino, check);
+	ret = fuse4fs_inum_access(ff, file->ino, check);
 	if (ret) {
 		/*
 		 * In a regular (Linux) fs driver, the kernel will open
@@ -3160,7 +3163,7 @@ static int __op_open(struct fuse4fs *ff, const char *path,
 		 * also employ undocumented hacks (see above).
 		 */
 		if (check == R_OK) {
-			ret = check_inum_access(ff, file->ino, X_OK);
+			ret = fuse4fs_inum_access(ff, file->ino, X_OK);
 			if (ret)
 				goto out;
 			check = X_OK;
@@ -3271,7 +3274,7 @@ static int op_write(const char *path EXT2FS_ATTR((unused)),
 		goto out;
 	}
 
-	if (!fs_can_allocate(ff, FUSE4FS_B_TO_FSB(ff, len))) {
+	if (!fuse4fs_can_allocate(ff, FUSE4FS_B_TO_FSB(ff, len))) {
 		ret = -ENOSPC;
 		goto out;
 	}
@@ -3471,11 +3474,11 @@ static int op_getxattr(const char *path, const char *key, char *value,
 	}
 	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
 
-	ret = check_inum_access(ff, ino, R_OK);
+	ret = fuse4fs_inum_access(ff, ino, R_OK);
 	if (ret)
 		goto out;
 
-	ret = __getxattr(ff, ino, key, &ptr, &plen);
+	ret = fuse4fs_getxattr(ff, ino, key, &ptr, &plen);
 	if (ret)
 		goto out;
 
@@ -3541,7 +3544,7 @@ static int op_listxattr(const char *path, char *names, size_t len)
 	}
 	dbg_printf(ff, "%s: ino=%d\n", __func__, ino);
 
-	ret = check_inum_access(ff, ino, R_OK);
+	ret = fuse4fs_inum_access(ff, ino, R_OK);
 	if (ret)
 		goto out;
 
@@ -3622,7 +3625,7 @@ static int op_setxattr(const char *path EXT2FS_ATTR((unused)),
 	}
 	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
 
-	ret = check_inum_access(ff, ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ino, W_OK);
 	if (ret == -EACCES) {
 		ret = -EPERM;
 		goto out;
@@ -3711,7 +3714,7 @@ static int op_removexattr(const char *path, const char *key)
 		goto out;
 	}
 
-	if (!fs_can_allocate(ff, 1)) {
+	if (!fuse4fs_can_allocate(ff, 1)) {
 		ret = -ENOSPC;
 		goto out;
 	}
@@ -3723,7 +3726,7 @@ static int op_removexattr(const char *path, const char *key)
 	}
 	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
 
-	ret = check_inum_access(ff, ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ino, W_OK);
 	if (ret)
 		goto out;
 
@@ -3910,7 +3913,7 @@ static int op_access(const char *path, int mask)
 		goto out;
 	}
 
-	ret = check_inum_access(ff, ino, mask);
+	ret = fuse4fs_inum_access(ff, ino, mask);
 	if (ret)
 		goto out;
 
@@ -3950,7 +3953,7 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 	*node_name = 0;
 
 	fs = fuse4fs_start(ff);
-	if (!fs_can_allocate(ff, 1)) {
+	if (!fuse4fs_can_allocate(ff, 1)) {
 		ret = -ENOSPC;
 		goto out2;
 	}
@@ -3962,7 +3965,7 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 		goto out2;
 	}
 
-	ret = check_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
@@ -4029,7 +4032,7 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 
 	ext2fs_inode_alloc_stats2(fs, child, 1, 0);
 
-	ret = propagate_default_acls(ff, parent, child, inode.i_mode);
+	ret = fuse4fs_propagate_default_acls(ff, parent, child, inode.i_mode);
 	if (ret)
 		goto out2;
 
@@ -4077,7 +4080,7 @@ static int op_utimens(const char *path, const struct timespec ctv[2],
 	 */
 	if (ctv[0].tv_nsec == UTIME_NOW && ctv[1].tv_nsec == UTIME_NOW)
 		access |= A_OK;
-	ret = check_inum_access(ff, ino, access);
+	ret = fuse4fs_inum_access(ff, ino, access);
 	if (ret)
 		goto out;
 
@@ -4162,7 +4165,7 @@ static int ioctl_setflags(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 	if (err)
 		return translate_error(fs, fh->ino, err);
 
-	if (want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
+	if (fuse4fs_want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
 		return -EPERM;
 
 	ret = set_iflags(&inode, flags);
@@ -4211,7 +4214,7 @@ static int ioctl_setversion(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 	if (err)
 		return translate_error(fs, fh->ino, err);
 
-	if (want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
+	if (fuse4fs_want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
 		return -EPERM;
 
 	inode.i_generation = generation;
@@ -4336,7 +4339,7 @@ static int ioctl_fssetxattr(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 	if (err)
 		return translate_error(fs, fh->ino, err);
 
-	if (want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
+	if (fuse4fs_want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
 		return -EPERM;
 
 	ret = set_xflags(&inode, fsx->fsx_xflags);
@@ -4465,7 +4468,7 @@ static int ioctl_shutdown(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 	struct fuse_context *ctxt = fuse_get_context();
 	ext2_filsys fs = ff->fs;
 
-	if (!is_superuser(ff, ctxt))
+	if (!fuse4fs_is_superuser(ff, ctxt))
 		return -EPERM;
 
 	err_printf(ff, "%s.\n", _("shut down requested"));
@@ -4584,7 +4587,7 @@ static int fuse4fs_allocate_range(struct fuse4fs *ff,
 		   (unsigned long long)len,
 		   (unsigned long long)start,
 		   (unsigned long long)end);
-	if (!fs_can_allocate(ff, FUSE4FS_B_TO_FSB(ff, len)))
+	if (!fuse4fs_can_allocate(ff, FUSE4FS_B_TO_FSB(ff, len)))
 		return -ENOSPC;
 
 	err = fuse4fs_read_inode(fs, fh->ino, &inode);
@@ -4627,9 +4630,9 @@ static int fuse4fs_allocate_range(struct fuse4fs *ff,
 	return err;
 }
 
-static errcode_t clean_block_middle(struct fuse4fs *ff, ext2_ino_t ino,
-				    struct ext2_inode_large *inode,
-				    off_t offset, off_t len, char **buf)
+static errcode_t fuse4fs_zero_middle(struct fuse4fs *ff, ext2_ino_t ino,
+				     struct ext2_inode_large *inode,
+				     off_t offset, off_t len, char **buf)
 {
 	ext2_filsys fs = ff->fs;
 	blk64_t blk;
@@ -4663,9 +4666,9 @@ static errcode_t clean_block_middle(struct fuse4fs *ff, ext2_ino_t ino,
 	return io_channel_write_blk64(fs->io, blk, 1, *buf);
 }
 
-static errcode_t clean_block_edge(struct fuse4fs *ff, ext2_ino_t ino,
-				  struct ext2_inode_large *inode, off_t offset,
-				  int clean_before, char **buf)
+static errcode_t fuse4fs_zero_edge(struct fuse4fs *ff, ext2_ino_t ino,
+				   struct ext2_inode_large *inode, off_t offset,
+				   int clean_before, char **buf)
 {
 	ext2_filsys fs = ff->fs;
 	blk64_t blk;
@@ -4756,13 +4759,13 @@ static int fuse4fs_punch_range(struct fuse4fs *ff,
 
 	/* Zero everything before the first block and after the last block */
 	if (FUSE4FS_B_TO_FSBT(ff, offset) == FUSE4FS_B_TO_FSBT(ff, offset + len))
-		err = clean_block_middle(ff, fh->ino, &inode, offset,
+		err = fuse4fs_zero_middle(ff, fh->ino, &inode, offset,
 					 len, &buf);
 	else {
-		err = clean_block_edge(ff, fh->ino, &inode, offset, 0, &buf);
+		err = fuse4fs_zero_edge(ff, fh->ino, &inode, offset, 0, &buf);
 		if (!err)
-			err = clean_block_edge(ff, fh->ino, &inode,
-					       offset + len, 1, &buf);
+			err = fuse4fs_zero_edge(ff, fh->ino, &inode,
+						offset + len, 1, &buf);
 	}
 	if (buf)
 		ext2fs_free_mem(&buf);

[PATCH 05/21] fuse4fs: convert to low level API

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Convert fuse4fs to the lowlevel fuse API.  Amir supplied the auto
translation; I ported and cleaned it up by hand, and did the QA work to
make sure it still runs correctly.

Co-developed-by: Claude claude-4-sonnet
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c | 2012 ++++++++++++++++++++++++++++-------------------------
 1 file changed, 1072 insertions(+), 940 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index a4eeb86201db0c..8b65dd1b419eaa 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -41,7 +41,7 @@
 # define __SET_FOB_FOR_FUSE
 # define _FILE_OFFSET_BITS 64
 #endif /* _FILE_OFFSET_BITS */
-#include <fuse.h>
+#include <fuse_lowlevel.h>
 #ifdef __SET_FOB_FOR_FUSE
 # undef _FILE_OFFSET_BITS
 #endif /* __SET_FOB_FOR_FUSE */
@@ -116,6 +116,8 @@
 #endif
 #endif /* !defined(ENODATA) */
 
+#define FUSE4FS_ATTR_TIMEOUT	(0.0)
+
 static inline uint64_t round_up(uint64_t b, unsigned int align)
 {
 	unsigned int m;
@@ -254,16 +256,18 @@ struct fuse4fs {
 	/* options set by fuse_opt_parse must be of type int */
 	int timing;
 #endif
+	struct fuse_session *fuse;
 };
 
-#define FUSE4FS_CHECK_HANDLE(ff, fh) \
+#define FUSE4FS_CHECK_HANDLE(req, fh) \
 	do { \
 		if ((fh) == NULL || (fh)->magic != FUSE4FS_FILE_MAGIC) { \
 			fprintf(stderr, \
 				"FUSE4FS: Corrupt in-memory file handle at %s:%d!\n", \
 				__func__, __LINE__); \
 			fflush(stderr); \
-			return -EUCLEAN; \
+			fuse_reply_err(req, EUCLEAN); \
+			return; \
 		} \
 	} while (0)
 
@@ -275,19 +279,52 @@ struct fuse4fs {
 				__func__, __LINE__); \
 			fflush(stderr); \
 			retcode; \
+			return; \
 		} \
 		if ((ff)->opstate == F4OP_SHUTDOWN) { \
 			shutcode; \
+			return; \
 		} \
 	} while (0)
 
-#define FUSE4FS_CHECK_CONTEXT(ff) \
-	__FUSE4FS_CHECK_CONTEXT((ff), return -EUCLEAN, return -EIO)
+#define FUSE4FS_CHECK_CONTEXT(req) \
+	__FUSE4FS_CHECK_CONTEXT(fuse4fs_get(req), \
+				fuse_reply_err((req), EUCLEAN), \
+				fuse_reply_err((req), EIO))
 #define FUSE4FS_CHECK_CONTEXT_RETURN(ff) \
 	__FUSE4FS_CHECK_CONTEXT((ff), return, return)
 #define FUSE4FS_CHECK_CONTEXT_ABORT(ff) \
 	__FUSE4FS_CHECK_CONTEXT((ff), abort(), abort())
 
+static inline void fuse4fs_ino_from_fuse(ext2_ino_t *inop, fuse_ino_t fino)
+{
+	if (fino == FUSE_ROOT_ID)
+		*inop = EXT2_ROOT_INO;
+	else
+		*inop = fino;
+}
+
+static inline void fuse4fs_ino_to_fuse(fuse_ino_t *finop, ext2_ino_t ino)
+{
+	if (ino == EXT2_ROOT_INO)
+		*finop = FUSE_ROOT_ID;
+	else
+		*finop = ino;
+}
+
+#define FUSE4FS_CONVERT_FINO(req, ext2_inop, fuse_ino) \
+	do { \
+		if ((fuse_ino) > UINT32_MAX) { \
+			fprintf(stderr, \
+				"FUSE4FS: Bogus inode number 0x%llx at %s:%d!\n", \
+				(unsigned long long)(fuse_ino), __func__, __LINE__); \
+			fflush(stderr); \
+			fuse_reply_err((req), EIO); \
+			return; \
+		} \
+		fuse4fs_ino_from_fuse(ext2_inop, fuse_ino); \
+	} while (0)
+
 static int __translate_error(ext2_filsys fs, ext2_ino_t ino, errcode_t err,
 			     const char *func, int line);
 #define translate_error(fs, ino, err) __translate_error((fs), (ino), (err), \
@@ -454,11 +491,9 @@ static inline errcode_t fuse4fs_write_inode(ext2_filsys fs, ext2_ino_t ino,
 				       sizeof(*inode));
 }
 
-static inline struct fuse4fs *fuse4fs_get(void)
+static inline struct fuse4fs *fuse4fs_get(fuse_req_t req)
 {
-	struct fuse_context *ctxt = fuse_get_context();
-
-	return ctxt->private_data;
+	return (struct fuse4fs *)fuse_req_userdata(req);
 }
 
 static inline struct fuse4fs_file_handle *
@@ -471,6 +506,7 @@ static inline void
 fuse4fs_set_handle(struct fuse_file_info *fp, struct fuse4fs_file_handle *fh)
 {
 	fp->fh = (uintptr_t)fh;
+	fp->keep_cache = 1;
 }
 
 #ifdef HAVE_CLOCK_MONOTONIC
@@ -731,7 +767,7 @@ static int fuse4fs_is_writeable(const struct fuse4fs *ff)
 }
 
 static inline int fuse4fs_is_superuser(struct fuse4fs *ff,
-				       const struct fuse_context *ctxt)
+				       const struct fuse_ctx *ctxt)
 {
 	if (ff->fakeroot)
 		return 1;
@@ -739,7 +775,7 @@ static inline int fuse4fs_is_superuser(struct fuse4fs *ff,
 }
 
 static inline int fuse4fs_want_check_owner(struct fuse4fs *ff,
-					   const struct fuse_context *ctxt)
+					   const struct fuse_ctx *ctxt)
 {
 	/*
 	 * The kernel is responsible for access control, so we allow anything
@@ -782,9 +818,9 @@ static int fuse4fs_iflags_access(struct fuse4fs *ff, ext2_ino_t ino,
 	return 0;
 }
 
-static int fuse4fs_inum_access(struct fuse4fs *ff, ext2_ino_t ino, int mask)
+static int fuse4fs_inum_access(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			       ext2_ino_t ino, int mask)
 {
-	struct fuse_context *ctxt = fuse_get_context();
 	ext2_filsys fs = ff->fs;
 	struct ext2_inode inode;
 	mode_t perms;
@@ -1118,9 +1154,9 @@ static int fuse4fs_mount(struct fuse4fs *ff)
 	return 0;
 }
 
-static void op_destroy(void *p EXT2FS_ATTR((unused)))
+static void op_destroy(void *userdata)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = userdata;
 	ext2_filsys fs;
 	errcode_t err;
 
@@ -1302,24 +1338,13 @@ static inline int fuse_set_feature_flag(struct fuse_conn_info *conn,
 }
 #endif
 
-static void *op_init(struct fuse_conn_info *conn,
-		     struct fuse_config *cfg EXT2FS_ATTR((unused)))
+static void op_init(void *userdata, struct fuse_conn_info *conn)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = userdata;
 	ext2_filsys fs;
 
 	FUSE4FS_CHECK_CONTEXT_ABORT(ff);
 
-	/*
-	 * Configure logging a second time, because libfuse might have
-	 * redirected std{out,err} as part of daemonization.  If this fails,
-	 * give up and move on.
-	 */
-	fuse4fs_setup_logging(ff);
-	if (ff->logfd >= 0)
-		close(ff->logfd);
-	ff->logfd = -1;
-
 	fs = ff->fs;
 	dbg_printf(ff, "%s: dev=%s\n", __func__, fs->device_name);
 #ifdef FUSE_CAP_IOCTL_DIR
@@ -1336,10 +1361,6 @@ static void *op_init(struct fuse_conn_info *conn,
 	fuse_set_feature_flag(conn, FUSE_CAP_NO_EXPORT_SUPPORT);
 #endif
 	conn->time_gran = 1;
-	cfg->use_ino = 1;
-	if (ff->debug)
-		cfg->debug = 1;
-	cfg->nullpath_ok = 1;
 
 	if (ff->kernel) {
 		char uuid[UUID_STR_SIZE];
@@ -1364,132 +1385,151 @@ static void *op_init(struct fuse_conn_info *conn,
 	 */
 	conn->want = conn->want_ext & 0xFFFFFFFF;
 #endif
-	return ff;
 }
 
-static int stat_inode(ext2_filsys fs, ext2_ino_t ino, struct stat *statbuf)
+struct fuse4fs_stat {
+	struct fuse_entry_param	entry;
+};
+
+static int fuse4fs_stat_inode(struct fuse4fs *ff, ext2_ino_t ino,
+			      struct ext2_inode_large *inodep,
+			      struct fuse4fs_stat *fstat)
 {
 	struct ext2_inode_large inode;
+	ext2_filsys fs = ff->fs;
+	struct fuse_entry_param *entry = &fstat->entry;
+	struct stat *statbuf = &entry->attr;
 	dev_t fakedev = 0;
 	errcode_t err;
-	int ret = 0;
 	struct timespec tv;
 
-	err = fuse4fs_read_inode(fs, ino, &inode);
-	if (err)
-		return translate_error(fs, ino, err);
+	memset(fstat, 0, sizeof(*fstat));
+
+	if (!inodep) {
+		err = fuse4fs_read_inode(fs, ino, &inode);
+		if (err)
+			return translate_error(fs, ino, err);
+		inodep = &inode;
+	}
 
 	memcpy(&fakedev, fs->super->s_uuid, sizeof(fakedev));
 	statbuf->st_dev = fakedev;
 	statbuf->st_ino = ino;
-	statbuf->st_mode = inode.i_mode;
-	statbuf->st_nlink = inode.i_links_count;
-	statbuf->st_uid = inode_uid(inode);
-	statbuf->st_gid = inode_gid(inode);
-	statbuf->st_size = EXT2_I_SIZE(&inode);
+	statbuf->st_mode = inodep->i_mode;
+	statbuf->st_nlink = inodep->i_links_count;
+	statbuf->st_uid = inode_uid(*inodep);
+	statbuf->st_gid = inode_gid(*inodep);
+	statbuf->st_size = EXT2_I_SIZE(inodep);
 	statbuf->st_blksize = fs->blocksize;
 	statbuf->st_blocks = ext2fs_get_stat_i_blocks(fs,
-						EXT2_INODE(&inode));
-	EXT4_INODE_GET_XTIME(i_atime, &tv, &inode);
+						EXT2_INODE(inodep));
+	EXT4_INODE_GET_XTIME(i_atime, &tv, inodep);
 #if HAVE_STRUCT_STAT_ST_ATIM
 	statbuf->st_atim = tv;
 #else
 	statbuf->st_atime = tv.tv_sec;
 #endif
-	EXT4_INODE_GET_XTIME(i_mtime, &tv, &inode);
+	EXT4_INODE_GET_XTIME(i_mtime, &tv, inodep);
 #if HAVE_STRUCT_STAT_ST_ATIM
 	statbuf->st_mtim = tv;
 #else
 	statbuf->st_mtime = tv.tv_sec;
 #endif
-	EXT4_INODE_GET_XTIME(i_ctime, &tv, &inode);
+	EXT4_INODE_GET_XTIME(i_ctime, &tv, inodep);
 #if HAVE_STRUCT_STAT_ST_ATIM
 	statbuf->st_ctim = tv;
 #else
 	statbuf->st_ctime = tv.tv_sec;
 #endif
-	if (LINUX_S_ISCHR(inode.i_mode) ||
-	    LINUX_S_ISBLK(inode.i_mode)) {
-		if (inode.i_block[0])
-			statbuf->st_rdev = inode.i_block[0];
+	if (LINUX_S_ISCHR(inodep->i_mode) ||
+	    LINUX_S_ISBLK(inodep->i_mode)) {
+		if (inodep->i_block[0])
+			statbuf->st_rdev = inodep->i_block[0];
 		else
-			statbuf->st_rdev = inode.i_block[1];
+			statbuf->st_rdev = inodep->i_block[1];
 	}
 
-	return ret;
-}
-
-static int __fuse4fs_file_ino(struct fuse4fs *ff, const char *path,
-			      struct fuse_file_info *fp EXT2FS_ATTR((unused)),
-			      ext2_ino_t *inop,
-			      const char *func,
-			      int line)
-{
-	ext2_filsys fs = ff->fs;
-	errcode_t err;
-
-	if (fp) {
-		struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
-
-		if (fh->ino == 0)
-			return -ESTALE;
-
-		*inop = fh->ino;
-		dbg_printf(ff, "%s: get ino=%d\n", func, fh->ino);
-		return 0;
-	}
-
-	dbg_printf(ff, "%s: get path=%s\n", func, path);
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, inop);
-	if (err)
-		return __translate_error(fs, 0, err, func, line);
+	fuse4fs_ino_to_fuse(&entry->ino, ino);
+	entry->generation = inodep->i_generation;
+	entry->attr_timeout = FUSE4FS_ATTR_TIMEOUT;
+	entry->entry_timeout = FUSE4FS_ATTR_TIMEOUT;
 
 	return 0;
 }
 
-# define fuse4fs_file_ino(ff, path, fp, inop) \
-	__fuse4fs_file_ino((ff), (path), (fp), (inop), __func__, __LINE__)
-
-static int op_getattr(const char *path, struct stat *statbuf,
-		      struct fuse_file_info *fi)
+static void op_lookup(fuse_req_t req, fuse_ino_t fino, const char *name)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_stat fstat;
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
-	ext2_ino_t ino;
+	ext2_ino_t parent, child;
+	errcode_t err;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &parent, fino);
+	dbg_printf(ff, "%s: parent=%d name='%s'\n", __func__, parent, name);
 	fs = fuse4fs_start(ff);
-	ret = fuse4fs_file_ino(ff, path, fi, &ino);
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, parent, name, &child);
+	if (err || child == 0) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+
+	ret = fuse4fs_stat_inode(ff, child, NULL, &fstat);
 	if (ret)
 		goto out;
-	ret = stat_inode(fs, ino, statbuf);
+
 out:
 	fuse4fs_finish(ff, ret);
-	return ret;
+
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_entry(req, &fstat.entry);
 }
 
-static int op_readlink(const char *path, char *buf, size_t len)
+static void op_getattr(fuse_req_t req, fuse_ino_t fino,
+		       struct fuse_file_info *fi EXT2FS_ATTR((unused)))
 {
-	struct fuse4fs *ff = fuse4fs_get();
-	ext2_filsys fs;
-	errcode_t err;
+	struct fuse4fs_stat fstat;
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_ino_t ino;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+	fuse4fs_start(ff);
+	ret = fuse4fs_stat_inode(ff, ino, NULL, &fstat);
+	fuse4fs_finish(ff, ret);
+
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_attr(req, &fstat.entry.attr,
+				fstat.entry.attr_timeout);
+}
+
+static void op_readlink(fuse_req_t req, fuse_ino_t fino)
+{
 	struct ext2_inode inode;
+	char buf[PATH_MAX + 1];
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_filsys fs;
+	ext2_file_t file;
+	errcode_t err;
+	ext2_ino_t ino;
+	size_t len = PATH_MAX;
 	unsigned int got;
-	ext2_file_t file;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: path=%s\n", __func__, path);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+	dbg_printf(ff, "%s: ino=%d\n", __func__, ino);
 	fs = fuse4fs_start(ff);
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
-	if (err || ino == 0) {
-		ret = translate_error(fs, 0, err);
-		goto out;
-	}
 
-	err = ext2fs_read_inode(fs, ino, &inode);
+	err = ext2fs_read_inode(fs, fino, &inode);
 	if (err) {
 		ret = translate_error(fs, ino, err);
 		goto out;
@@ -1500,7 +1540,6 @@ static int op_readlink(const char *path, char *buf, size_t len)
 		goto out;
 	}
 
-	len--;
 	if (inode.i_size < len)
 		len = inode.i_size;
 	if (ext2fs_is_fast_symlink(&inode))
@@ -1538,7 +1577,11 @@ static int op_readlink(const char *path, char *buf, size_t len)
 
 out:
 	fuse4fs_finish(ff, ret);
-	return ret;
+
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_readlink(req, buf);
 }
 
 static int fuse4fs_getxattr(struct fuse4fs *ff, ext2_ino_t ino,
@@ -1644,11 +1687,12 @@ static inline void fuse4fs_set_gid(struct ext2_inode_large *inode, gid_t gid)
 	ext2fs_set_i_gid_high(*inode, gid >> 16);
 }
 
-static int fuse4fs_new_child_gid(struct fuse4fs *ff, ext2_ino_t parent,
-				 gid_t *gid, int *parent_sgid)
+static int fuse4fs_new_child_gid(struct fuse4fs *ff,
+				 const struct fuse_ctx *ctxt,
+				 ext2_ino_t parent, gid_t *gid,
+				 int *parent_sgid)
 {
 	struct ext2_inode_large inode;
-	struct fuse_context *ctxt = fuse_get_context();
 	errcode_t err;
 
 	err = fuse4fs_read_inode(ff->fs, parent, &inode);
@@ -1724,36 +1768,44 @@ static void fuse4fs_set_extra_isize(struct fuse4fs *ff, ext2_ino_t ino,
 	inode->i_extra_isize = extra;
 }
 
-static int op_mknod(const char *path, mode_t mode, dev_t dev)
+static void fuse4fs_reply_entry(fuse_req_t req, ext2_ino_t ino,
+				struct ext2_inode_large *inode, int ret)
 {
-	struct fuse_context *ctxt = fuse_get_context();
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs_stat fstat;
+	struct fuse4fs *ff = fuse4fs_get(req);
+
+	if (ret) {
+		fuse_reply_err(req, -ret);
+		return;
+	}
+
+	/* Get stat info for the new entry */
+	ret = fuse4fs_stat_inode(ff, ino, inode, &fstat);
+	if (ret) {
+		fuse_reply_err(req, -ret);
+		return;
+	}
+
+	fuse_reply_entry(req, &fstat.entry);
+}
+
+static void op_mknod(fuse_req_t req, fuse_ino_t fino, const char *name,
+		     mode_t mode, dev_t dev)
+{
+	struct ext2_inode_large inode;
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	ext2_ino_t parent, child;
-	char *temp_path;
 	errcode_t err;
-	char *node_name, a;
 	int filetype;
-	struct ext2_inode_large inode;
 	gid_t gid;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: path=%s mode=0%o dev=0x%x\n", __func__, path, mode,
-		   (unsigned int)dev);
-	temp_path = strdup(path);
-	if (!temp_path) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name = strrchr(temp_path, '/');
-	if (!node_name) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name++;
-	a = *node_name;
-	*node_name = 0;
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &parent, fino);
+	dbg_printf(ff, "%s: parent=%d name='%s' mode=0%o dev=0x%x\n",
+		   __func__, parent, name, mode, (unsigned int)dev);
 
 	fs = fuse4fs_start(ff);
 	if (!fuse4fs_can_allocate(ff, 2)) {
@@ -1761,33 +1813,14 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
 		goto out2;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
-			   &parent);
-	if (err) {
-		ret = translate_error(fs, 0, err);
-		goto out2;
-	}
-
-	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
-	*node_name = a;
+	/* On a low level server, mknod handles all non-directory types */
+	filetype = ext2_file_type(mode);
 
-	if (LINUX_S_ISCHR(mode))
-		filetype = EXT2_FT_CHRDEV;
-	else if (LINUX_S_ISBLK(mode))
-		filetype = EXT2_FT_BLKDEV;
-	else if (LINUX_S_ISFIFO(mode))
-		filetype = EXT2_FT_FIFO;
-	else if (LINUX_S_ISSOCK(mode))
-		filetype = EXT2_FT_SOCK;
-	else {
-		ret = -EINVAL;
-		goto out2;
-	}
-
-	err = fuse4fs_new_child_gid(ff, parent, &gid, NULL);
+	err = fuse4fs_new_child_gid(ff, ctxt, parent, &gid, NULL);
 	if (err)
 		goto out2;
 
@@ -1797,9 +1830,9 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
 		goto out2;
 	}
 
-	dbg_printf(ff, "%s: create ino=%d/name=%s in dir=%d\n", __func__, child,
-		   node_name, parent);
-	err = ext2fs_link(fs, parent, node_name, child,
+	dbg_printf(ff, "%s: create ino=%d name='%s' in dir=%d\n", __func__,
+		   child, name, parent);
+	err = ext2fs_link(fs, parent, name, child,
 			  filetype | EXT2FS_LINK_EXPAND);
 	if (err) {
 		ret = translate_error(fs, parent, err);
@@ -1848,42 +1881,28 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
 
 out2:
 	fuse4fs_finish(ff, ret);
-out:
-	free(temp_path);
-	return ret;
+	fuse4fs_reply_entry(req, child, &inode, ret);
 }
 
-static int op_mkdir(const char *path, mode_t mode)
+static void op_mkdir(fuse_req_t req, fuse_ino_t fino, const char *name,
+		     mode_t mode)
 {
-	struct fuse_context *ctxt = fuse_get_context();
-	struct fuse4fs *ff = fuse4fs_get();
+	struct ext2_inode_large inode;
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	ext2_ino_t parent, child;
-	char *temp_path;
 	errcode_t err;
-	char *node_name, a;
-	struct ext2_inode_large inode;
 	char *block;
 	blk64_t blk;
 	int ret = 0;
 	gid_t gid;
 	int parent_sgid;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: path=%s mode=0%o\n", __func__, path, mode);
-	temp_path = strdup(path);
-	if (!temp_path) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name = strrchr(temp_path, '/');
-	if (!node_name) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name++;
-	a = *node_name;
-	*node_name = 0;
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &parent, fino);
+	dbg_printf(ff, "%s: parent=%d name='%s' mode=0%o\n",
+		   __func__, parent, name, mode);
 
 	fs = fuse4fs_start(ff);
 	if (!fuse4fs_can_allocate(ff, 1)) {
@@ -1891,25 +1910,15 @@ static int op_mkdir(const char *path, mode_t mode)
 		goto out2;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
-			   &parent);
-	if (err) {
-		ret = translate_error(fs, 0, err);
-		goto out2;
-	}
-
-	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
-	err = fuse4fs_new_child_gid(ff, parent, &gid, &parent_sgid);
+	err = fuse4fs_new_child_gid(ff, ctxt, parent, &gid, &parent_sgid);
 	if (err)
 		goto out2;
 
-	*node_name = a;
-
-	err = ext2fs_mkdir2(fs, parent, 0, 0, EXT2FS_LINK_EXPAND,
-			    node_name, NULL);
+	err = ext2fs_mkdir2(fs, parent, 0, 0, EXT2FS_LINK_EXPAND, name, NULL);
 	if (err) {
 		ret = translate_error(fs, parent, err);
 		goto out2;
@@ -1920,14 +1929,13 @@ static int op_mkdir(const char *path, mode_t mode)
 		goto out2;
 
 	/* Still have to update the uid/gid of the dir */
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
-			   &child);
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, parent, name, &child);
 	if (err) {
 		ret = translate_error(fs, 0, err);
 		goto out2;
 	}
-	dbg_printf(ff, "%s: created ino=%d/path=%s in dir=%d\n", __func__, child,
-		   node_name, parent);
+	dbg_printf(ff, "%s: created ino=%d name='%s' in dir=%d\n",
+		   __func__, child, name, parent);
 
 	err = fuse4fs_read_inode(fs, child, &inode);
 	if (err) {
@@ -1983,55 +1991,7 @@ static int op_mkdir(const char *path, mode_t mode)
 	ext2fs_free_mem(&block);
 out2:
 	fuse4fs_finish(ff, ret);
-out:
-	free(temp_path);
-	return ret;
-}
-
-static int fuse4fs_unlink(struct fuse4fs *ff, const char *path,
-			  ext2_ino_t *parent)
-{
-	ext2_filsys fs = ff->fs;
-	errcode_t err;
-	ext2_ino_t dir;
-	char *filename = strdup(path);
-	char *base_name;
-	int ret;
-
-	base_name = strrchr(filename, '/');
-	if (base_name) {
-		*base_name++ = '\0';
-		err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, filename,
-				   &dir);
-		if (err) {
-			free(filename);
-			return translate_error(fs, 0, err);
-		}
-	} else {
-		dir = EXT2_ROOT_INO;
-		base_name = filename;
-	}
-
-	ret = fuse4fs_inum_access(ff, dir, W_OK);
-	if (ret) {
-		free(filename);
-		return ret;
-	}
-
-	dbg_printf(ff, "%s: unlinking name=%s from dir=%d\n", __func__,
-		   base_name, dir);
-	err = ext2fs_unlink(fs, dir, base_name, 0, 0);
-	free(filename);
-	if (err)
-		return translate_error(fs, dir, err);
-
-	ret = update_mtime(fs, dir, NULL);
-	if (ret)
-		return ret;
-
-	if (parent)
-		*parent = dir;
-	return 0;
+	fuse4fs_reply_entry(req, child, &inode, ret);
 }
 
 static int fuse4fs_remove_ea_inodes(struct fuse4fs *ff, ext2_ino_t ino,
@@ -2140,49 +2100,78 @@ static int fuse4fs_remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 	return 0;
 }
 
-static int __op_unlink(struct fuse4fs *ff, const char *path)
+static int fuse4fs_unlink(struct fuse4fs *ff, ext2_ino_t parent,
+			  const char *name, ext2_ino_t child)
 {
 	ext2_filsys fs = ff->fs;
-	ext2_ino_t parent, ino;
 	errcode_t err;
 	int ret = 0;
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
+	err = ext2fs_unlink(fs, parent, name, child, 0);
+	if (err) {
+		ret = translate_error(fs, parent, err);
+		goto out;
+	}
+
+	ret = update_mtime(fs, parent, NULL);
+	if (ret)
+		goto out;
+out:
+	return ret;
+}
+
+static int fuse4fs_rmfile(struct fuse4fs *ff, ext2_ino_t parent,
+			  const char *name, ext2_ino_t child)
+{
+	int ret;
+
+	ret = fuse4fs_unlink(ff, parent, name, child);
+	if (ret)
+		return ret;
+
+	return fuse4fs_remove_inode(ff, child);
+}
+
+static void op_unlink(fuse_req_t req, fuse_ino_t fino, const char *name)
+{
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_filsys fs;
+	ext2_ino_t parent, child;
+	errcode_t err;
+	int ret;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &parent, fino);
+	fs = fuse4fs_start(ff);
+
+	/* Get the inode number for the file */
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, parent, name, &child);
 	if (err) {
 		ret = translate_error(fs, 0, err);
 		goto out;
 	}
 
-	ret = fuse4fs_inum_access(ff, ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, child, W_OK);
 	if (ret)
 		goto out;
 
-	ret = fuse4fs_unlink(ff, path, &parent);
+	ret = fuse4fs_inum_access(ff, ctxt, parent, W_OK);
 	if (ret)
 		goto out;
 
-	ret = fuse4fs_remove_inode(ff, ino);
+	dbg_printf(ff, "%s: unlink parent=%d name='%s' child=%d\n",
+		   __func__, parent, name, child);
+	ret = fuse4fs_rmfile(ff, parent, name, child);
 	if (ret)
 		goto out;
 
 	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
 	if (ret)
 		goto out;
-
 out:
-	return ret;
-}
-
-static int op_unlink(const char *path)
-{
-	struct fuse4fs *ff = fuse4fs_get();
-	int ret;
-
-	FUSE4FS_CHECK_CONTEXT(ff);
-	fuse4fs_start(ff);
-	ret = __op_unlink(ff, path);
 	fuse4fs_finish(ff, ret);
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 
 struct rd_struct {
@@ -2213,51 +2202,36 @@ static int rmdir_proc(ext2_ino_t dir EXT2FS_ATTR((unused)),
 	return 0;
 }
 
-static int __op_rmdir(struct fuse4fs *ff, const char *path)
+static int fuse4fs_rmdir(struct fuse4fs *ff, ext2_ino_t parent,
+			 const char *name, ext2_ino_t child)
 {
 	ext2_filsys fs = ff->fs;
-	ext2_ino_t parent, child;
 	errcode_t err;
 	struct ext2_inode_large inode;
-	struct rd_struct rds;
+	struct rd_struct rds = {
+		.parent = 0,
+		.empty = 1,
+	};
 	int ret = 0;
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &child);
-	if (err) {
-		ret = translate_error(fs, 0, err);
-		goto out;
-	}
-	dbg_printf(ff, "%s: rmdir path=%s ino=%d\n", __func__, path, child);
-
-	ret = fuse4fs_inum_access(ff, child, W_OK);
-	if (ret)
-		goto out;
-
-	rds.parent = 0;
-	rds.empty = 1;
-
 	err = ext2fs_dir_iterate2(fs, child, 0, 0, rmdir_proc, &rds);
 	if (err) {
 		ret = translate_error(fs, child, err);
 		goto out;
 	}
 
-	/* the kernel checks parent permissions before emptiness */
+	/* Make sure we found a dotdot entry */
 	if (rds.parent == 0) {
 		ret = translate_error(fs, child, EXT2_ET_FILESYSTEM_CORRUPTED);
 		goto out;
 	}
 
-	ret = fuse4fs_inum_access(ff, rds.parent, W_OK);
-	if (ret)
-		goto out;
-
 	if (rds.empty == 0) {
 		ret = -ENOTEMPTY;
 		goto out;
 	}
 
-	ret = fuse4fs_unlink(ff, path, &parent);
+	ret = fuse4fs_unlink(ff, parent, name, child);
 	if (ret)
 		goto out;
 	/* Directories have to be "removed" twice. */
@@ -2288,78 +2262,85 @@ static int __op_rmdir(struct fuse4fs *ff, const char *path)
 		}
 	}
 
-	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
-	if (ret)
-		goto out;
-
 out:
 	return ret;
 }
 
-static int op_rmdir(const char *path)
+static void op_rmdir(fuse_req_t req, fuse_ino_t fino, const char *name)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_filsys fs;
+	ext2_ino_t parent, child;
+	errcode_t err;
 	int ret;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	fuse4fs_start(ff);
-	ret = __op_rmdir(ff, path);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &parent, fino);
+	fs = fuse4fs_start(ff);
+
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, parent, name, &child);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+
+	ret = fuse4fs_inum_access(ff, ctxt, parent, W_OK);
+	if (ret)
+		goto out;
+
+	ret = fuse4fs_inum_access(ff, ctxt, child, W_OK);
+	if (ret)
+		goto out;
+
+	dbg_printf(ff, "%s: unlink parent=%d name='%s' child=%d\n",
+		   __func__, parent, name, child);
+	ret = fuse4fs_rmdir(ff, parent, name, child);
+	if (ret)
+		goto out;
+
+	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+	if (ret)
+		goto out;
+
+out:
 	fuse4fs_finish(ff, ret);
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 
-static int op_symlink(const char *src, const char *dest)
+static void op_symlink(fuse_req_t req, const char *target, fuse_ino_t fino,
+		       const char *name)
 {
-	struct fuse_context *ctxt = fuse_get_context();
-	struct fuse4fs *ff = fuse4fs_get();
-	ext2_filsys fs;
-	ext2_ino_t parent, child;
-	char *temp_path;
-	errcode_t err;
-	char *node_name, a;
 	struct ext2_inode_large inode;
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_filsys fs;
+	ext2_ino_t parent, child;
+	errcode_t err;
 	gid_t gid;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: symlink %s to %s\n", __func__, src, dest);
-	temp_path = strdup(dest);
-	if (!temp_path) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name = strrchr(temp_path, '/');
-	if (!node_name) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name++;
-	a = *node_name;
-	*node_name = 0;
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &parent, fino);
+	dbg_printf(ff, "%s: symlink dir=%d name='%s' target='%s'\n",
+		   __func__, parent, name, target);
 
 	fs = fuse4fs_start(ff);
-	if (!fs_can_allocate(ff, 1)) {
+	if (!fuse4fs_can_allocate(ff, 1)) {
 		ret = -ENOSPC;
 		goto out2;
 	}
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
-			   &parent);
-	*node_name = a;
-	if (err) {
-		ret = translate_error(fs, 0, err);
-		goto out2;
-	}
 
-	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
-	err = fuse4fs_new_child_gid(ff, parent, &gid, NULL);
+	err = fuse4fs_new_child_gid(ff, ctxt, parent, &gid, NULL);
 	if (err)
 		goto out2;
 
 	/* Create symlink */
-	err = ext2fs_symlink(fs, parent, 0, node_name, src);
+	err = ext2fs_symlink(fs, parent, 0, name, target);
 	if (err == EXT2_ET_DIR_NO_SPACE) {
 		err = ext2fs_expand_dir(fs, parent);
 		if (err) {
@@ -2367,7 +2348,7 @@ static int op_symlink(const char *src, const char *dest)
 			goto out2;
 		}
 
-		err = ext2fs_symlink(fs, parent, 0, node_name, src);
+		err = ext2fs_symlink(fs, parent, 0, name, target);
 	}
 	if (err) {
 		ret = translate_error(fs, parent, err);
@@ -2380,14 +2361,13 @@ static int op_symlink(const char *src, const char *dest)
 		goto out2;
 
 	/* Still have to update the uid/gid of the symlink */
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
-			   &child);
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, parent, name, &child);
 	if (err) {
 		ret = translate_error(fs, 0, err);
 		goto out2;
 	}
-	dbg_printf(ff, "%s: symlinking ino=%d/name=%s to dir=%d\n", __func__,
-		   child, node_name, parent);
+	dbg_printf(ff, "%s: symlinking dir=%d name='%s' child=%d\n",
+		   __func__, parent, name, child);
 
 	err = fuse4fs_read_inode(fs, child, &inode);
 	if (err) {
@@ -2413,9 +2393,7 @@ static int op_symlink(const char *src, const char *dest)
 
 out2:
 	fuse4fs_finish(ff, ret);
-out:
-	free(temp_path);
-	return ret;
+	fuse4fs_reply_entry(req, child, &inode, ret);
 }
 
 struct update_dotdot {
@@ -2441,39 +2419,43 @@ static int update_dotdot_helper(ext2_ino_t dir EXT2FS_ATTR((unused)),
 	return 0;
 }
 
-static int op_rename(const char *from, const char *to,
-		     unsigned int flags EXT2FS_ATTR((unused)))
+static void op_rename(fuse_req_t req, fuse_ino_t from_parent, const char *from,
+		      fuse_ino_t to_parent, const char *to, unsigned int flags)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	errcode_t err;
 	ext2_ino_t from_ino, to_ino, to_dir_ino, from_dir_ino;
-	char *temp_to = NULL, *temp_from = NULL;
-	char *cp, a;
 	struct ext2_inode inode;
 	struct update_dotdot ud;
 	int flushed = 0;
 	int ret = 0;
 
 	/* renameat2 is not supported */
-	if (flags)
-		return -ENOSYS;
+	if (flags) {
+		fuse_reply_err(req, ENOSYS);
+		return;
+	}
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: renaming %s to %s\n", __func__, from, to);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &from_dir_ino, from_parent);
+	FUSE4FS_CONVERT_FINO(req, &to_dir_ino, to_parent);
+	dbg_printf(ff, "%s: renaming dir=%d name='%s' to dir=%d name='%s'\n",
+		   __func__, from_dir_ino, from, to_dir_ino, to);
 	fs = fuse4fs_start(ff);
 	if (!fuse4fs_can_allocate(ff, 5)) {
 		ret = -ENOSPC;
 		goto out;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, from, &from_ino);
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, from_dir_ino, from, &from_ino);
 	if (err || from_ino == 0) {
 		ret = translate_error(fs, 0, err);
 		goto out;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, to, &to_ino);
+	err = ext2fs_namei(fs, EXT2_ROOT_INO, to_dir_ino, to, &to_ino);
 	if (err && err != EXT2_ET_FILE_NOT_FOUND) {
 		ret = translate_error(fs, 0, err);
 		goto out;
@@ -2482,136 +2464,80 @@ static int op_rename(const char *from, const char *to,
 	if (err == EXT2_ET_FILE_NOT_FOUND)
 		to_ino = 0;
 
+	dbg_printf(ff,
+ "%s: renaming dir=%d name='%s' child=%d to dir=%d name='%s' child=%d\n",
+		   __func__, from_dir_ino, from, from_ino, to_dir_ino, to,
+		   to_ino);
+
 	/* Already the same file? */
 	if (to_ino != 0 && to_ino == from_ino) {
 		ret = 0;
 		goto out;
 	}
 
-	ret = fuse4fs_inum_access(ff, from_ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, from_ino, W_OK);
 	if (ret)
 		goto out;
 
 	if (to_ino) {
-		ret = fuse4fs_inum_access(ff, to_ino, W_OK);
+		ret = fuse4fs_inum_access(ff, ctxt, to_ino, W_OK);
 		if (ret)
 			goto out;
 	}
 
-	temp_to = strdup(to);
-	if (!temp_to) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	temp_from = strdup(from);
-	if (!temp_from) {
-		ret = -ENOMEM;
-		goto out2;
-	}
-
-	/* Find parent dir of the source and check write access */
-	cp = strrchr(temp_from, '/');
-	if (!cp) {
-		ret = -EINVAL;
-		goto out2;
-	}
-
-	a = *(cp + 1);
-	*(cp + 1) = 0;
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_from,
-			   &from_dir_ino);
-	*(cp + 1) = a;
-	if (err) {
-		ret = translate_error(fs, 0, err);
-		goto out2;
-	}
-	if (from_dir_ino == 0) {
-		ret = -ENOENT;
-		goto out2;
-	}
-
-	ret = fuse4fs_inum_access(ff, from_dir_ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, from_dir_ino, W_OK);
 	if (ret)
-		goto out2;
-
-	/* Find parent dir of the destination and check write access */
-	cp = strrchr(temp_to, '/');
-	if (!cp) {
-		ret = -EINVAL;
-		goto out2;
-	}
-
-	a = *(cp + 1);
-	*(cp + 1) = 0;
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_to,
-			   &to_dir_ino);
-	*(cp + 1) = a;
-	if (err) {
-		ret = translate_error(fs, 0, err);
-		goto out2;
-	}
-	if (to_dir_ino == 0) {
-		ret = -ENOENT;
-		goto out2;
-	}
+		goto out;
 
-	ret = fuse4fs_inum_access(ff, to_dir_ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, to_dir_ino, W_OK);
 	if (ret)
-		goto out2;
+		goto out;
 
 	/* If the target exists, unlink it first */
 	if (to_ino != 0) {
 		err = ext2fs_read_inode(fs, to_ino, &inode);
 		if (err) {
 			ret = translate_error(fs, to_ino, err);
-			goto out2;
+			goto out;
 		}
 
-		dbg_printf(ff, "%s: unlinking %s ino=%d\n", __func__,
-			   LINUX_S_ISDIR(inode.i_mode) ? "dir" : "file",
-			   to_ino);
+		dbg_printf(ff, "%s: unlink dir=%d name='%s' child=%d\n",
+			   __func__, to_dir_ino, to, to_ino);
 		if (LINUX_S_ISDIR(inode.i_mode))
-			ret = __op_rmdir(ff, to);
+			ret = fuse4fs_rmdir(ff, to_dir_ino, to, to_ino);
 		else
-			ret = __op_unlink(ff, to);
+			ret = fuse4fs_rmfile(ff, to_dir_ino, to, to_ino);
 		if (ret)
-			goto out2;
+			goto out;
 	}
 
 	/* Get ready to do the move */
 	err = ext2fs_read_inode(fs, from_ino, &inode);
 	if (err) {
 		ret = translate_error(fs, from_ino, err);
-		goto out2;
+		goto out;
 	}
 
 	/* Link in the new file */
-	dbg_printf(ff, "%s: linking ino=%d/path=%s to dir=%d\n", __func__,
-		   from_ino, cp + 1, to_dir_ino);
-	err = ext2fs_link(fs, to_dir_ino, cp + 1, from_ino,
+	dbg_printf(ff, "%s: link dir=%d name='%s' child=%d\n",
+		   __func__, to_dir_ino, to, from_ino);
+	err = ext2fs_link(fs, to_dir_ino, to, from_ino,
 			  ext2_file_type(inode.i_mode) | EXT2FS_LINK_EXPAND);
 	if (err) {
 		ret = translate_error(fs, to_dir_ino, err);
-		goto out2;
+		goto out;
 	}
 
 	/* Update '..' pointer if dir */
-	err = ext2fs_read_inode(fs, from_ino, &inode);
-	if (err) {
-		ret = translate_error(fs, from_ino, err);
-		goto out2;
-	}
-
 	if (LINUX_S_ISDIR(inode.i_mode)) {
 		ud.new_dotdot = to_dir_ino;
-		dbg_printf(ff, "%s: updating .. entry for dir=%d\n", __func__,
-			   to_dir_ino);
+		dbg_printf(ff, "%s: updating .. entry for child=%d parent=%d\n",
+			   __func__, from_ino, to_dir_ino);
 		err = ext2fs_dir_iterate2(fs, from_ino, 0, NULL,
 					  update_dotdot_helper, &ud);
 		if (err) {
 			ret = translate_error(fs, from_ino, err);
-			goto out2;
+			goto out;
 		}
 
 		/* Decrease from_dir_ino's links_count */
@@ -2620,87 +2546,76 @@ static int op_rename(const char *from, const char *to,
 		err = ext2fs_read_inode(fs, from_dir_ino, &inode);
 		if (err) {
 			ret = translate_error(fs, from_dir_ino, err);
-			goto out2;
+			goto out;
 		}
 		inode.i_links_count--;
 		err = ext2fs_write_inode(fs, from_dir_ino, &inode);
 		if (err) {
 			ret = translate_error(fs, from_dir_ino, err);
-			goto out2;
+			goto out;
 		}
 
 		/* Increase to_dir_ino's links_count */
 		err = ext2fs_read_inode(fs, to_dir_ino, &inode);
 		if (err) {
 			ret = translate_error(fs, to_dir_ino, err);
-			goto out2;
+			goto out;
 		}
 		inode.i_links_count++;
 		err = ext2fs_write_inode(fs, to_dir_ino, &inode);
 		if (err) {
 			ret = translate_error(fs, to_dir_ino, err);
-			goto out2;
+			goto out;
 		}
 	}
 
 	/* Update timestamps */
 	ret = update_ctime(fs, from_ino, NULL);
 	if (ret)
-		goto out2;
+		goto out;
 
 	ret = update_mtime(fs, to_dir_ino, NULL);
 	if (ret)
-		goto out2;
+		goto out;
 
 	/* Remove the old file */
-	ret = fuse4fs_unlink(ff, from, NULL);
+	dbg_printf(ff, "%s: unlink dir=%d name='%s' child=%d\n",
+		   __func__, from_dir_ino, from, from_ino);
+	ret = fuse4fs_unlink(ff, from_dir_ino, from, from_ino);
 	if (ret)
-		goto out2;
+		goto out;
 
 	ret = fuse4fs_dirsync_flush(ff, from_dir_ino, &flushed);
 	if (ret)
-		goto out2;
+		goto out;
 
 	if (from_dir_ino != to_dir_ino && !flushed) {
 		ret = fuse4fs_dirsync_flush(ff, to_dir_ino, NULL);
 		if (ret)
-			goto out2;
+			goto out;
 	}
 
-out2:
-	free(temp_from);
-	free(temp_to);
 out:
 	fuse4fs_finish(ff, ret);
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 
-static int op_link(const char *src, const char *dest)
+static void op_link(fuse_req_t req, fuse_ino_t child_fino,
+		    fuse_ino_t parent_fino, const char *name)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct ext2_inode_large inode;
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
-	char *temp_path;
 	errcode_t err;
-	char *node_name, a;
-	ext2_ino_t parent, ino;
-	struct ext2_inode_large inode;
+	ext2_ino_t parent, child;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: src=%s dest=%s\n", __func__, src, dest);
-	temp_path = strdup(dest);
-	if (!temp_path) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name = strrchr(temp_path, '/');
-	if (!node_name) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name++;
-	a = *node_name;
-	*node_name = 0;
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &parent, parent_fino);
+	FUSE4FS_CONVERT_FINO(req, &child, child_fino);
+	dbg_printf(ff, "%s: link dir=%d name='%s' child=%d\n",
+		   __func__, parent, name, child);
 
 	fs = fuse4fs_start(ff);
 	if (!fuse4fs_can_allocate(ff, 2)) {
@@ -2708,48 +2623,32 @@ static int op_link(const char *src, const char *dest)
 		goto out2;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
-			   &parent);
-	*node_name = a;
-	if (err) {
-		err = -ENOENT;
-		goto out2;
-	}
-
-	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, src, &ino);
-	if (err || ino == 0) {
-		ret = translate_error(fs, 0, err);
-		goto out2;
-	}
-
-	err = fuse4fs_read_inode(fs, ino, &inode);
+	err = fuse4fs_read_inode(fs, child, &inode);
 	if (err) {
-		ret = translate_error(fs, ino, err);
+		ret = translate_error(fs, child, err);
 		goto out2;
 	}
 
-	ret = fuse4fs_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	ret = fuse4fs_iflags_access(ff, child, EXT2_INODE(&inode), W_OK);
 	if (ret)
 		goto out2;
 
 	inode.i_links_count++;
-	ret = update_ctime(fs, ino, &inode);
+	ret = update_ctime(fs, child, &inode);
 	if (ret)
 		goto out2;
 
-	err = fuse4fs_write_inode(fs, ino, &inode);
+	err = fuse4fs_write_inode(fs, child, &inode);
 	if (err) {
-		ret = translate_error(fs, ino, err);
+		ret = translate_error(fs, child, err);
 		goto out2;
 	}
 
-	dbg_printf(ff, "%s: linking ino=%d/name=%s to dir=%d\n", __func__, ino,
-		   node_name, parent);
-	err = ext2fs_link(fs, parent, node_name, ino,
+	err = ext2fs_link(fs, parent, name, child,
 			  ext2_file_type(inode.i_mode) | EXT2FS_LINK_EXPAND);
 	if (err) {
 		ret = translate_error(fs, parent, err);
@@ -2766,13 +2665,12 @@ static int op_link(const char *src, const char *dest)
 
 out2:
 	fuse4fs_finish(ff, ret);
-out:
-	free(temp_path);
-	return ret;
+	fuse4fs_reply_entry(req, child, &inode, ret);
 }
 
 /* Obtain group ids of the process that sent us a command(?) */
-static int fuse4fs_get_groups(struct fuse4fs *ff, gid_t **gids, size_t *nr_gids)
+static int fuse4fs_get_groups(struct fuse4fs *ff, fuse_req_t req, gid_t **gids,
+			      size_t *nr_gids)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
@@ -2785,7 +2683,7 @@ static int fuse4fs_get_groups(struct fuse4fs *ff, gid_t **gids, size_t *nr_gids)
 		if (err)
 			return translate_error(fs, 0, err);
 
-		ret = fuse_getgroups(nr, array);
+		ret = fuse_req_getgroups(req, nr, array);
 		if (ret < 0) {
 			/*
 			 * If there's an error, we failed to find the group
@@ -2817,10 +2715,10 @@ static int fuse4fs_get_groups(struct fuse4fs *ff, gid_t **gids, size_t *nr_gids)
  * that initiated the fuse request?  Returns 1 for yes, 0 for no, or a negative
  * errno.
  */
-static int fuse4fs_in_file_group(struct fuse_context *ctxt,
+static int fuse4fs_in_file_group(struct fuse4fs *ff, fuse_req_t req,
 				 const struct ext2_inode_large *inode)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
 	gid_t *gids = NULL;
 	size_t i, nr_gids = 0;
 	gid_t gid = inode_gid(*inode);
@@ -2830,7 +2728,7 @@ static int fuse4fs_in_file_group(struct fuse_context *ctxt,
 	if (ctxt->gid == gid)
 		return 1;
 
-	ret = fuse4fs_get_groups(ff, &gids, &nr_gids);
+	ret = fuse4fs_get_groups(ff, req, &gids, &nr_gids);
 	if (ret == -ENOENT) {
 		/* magic return code for "could not get caller group info" */
 		return 0;
@@ -2850,37 +2748,21 @@ static int fuse4fs_in_file_group(struct fuse_context *ctxt,
 	return ret;
 }
 
-static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
+static int fuse4fs_chmod(struct fuse4fs *ff, fuse_req_t req, ext2_ino_t ino,
+			 mode_t mode, struct ext2_inode_large *inode)
 {
-	struct fuse_context *ctxt = fuse_get_context();
-	struct fuse4fs *ff = fuse4fs_get();
-	ext2_filsys fs;
-	errcode_t err;
-	ext2_ino_t ino;
-	struct ext2_inode_large inode;
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	fs = fuse4fs_start(ff);
-	ret = fuse4fs_file_ino(ff, path, fi, &ino);
-	if (ret)
-		goto out;
-	dbg_printf(ff, "%s: path=%s mode=0%o ino=%d\n", __func__, path, mode, ino);
-
-	err = fuse4fs_read_inode(fs, ino, &inode);
-	if (err) {
-		ret = translate_error(fs, ino, err);
-		goto out;
-	}
+	dbg_printf(ff, "%s: ino=%d mode=0%o\n", __func__, ino, mode);
 
-	ret = fuse4fs_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	ret = fuse4fs_iflags_access(ff, ino, EXT2_INODE(inode), W_OK);
 	if (ret)
-		goto out;
+		return ret;
 
-	if (fuse4fs_want_check_owner(ff, ctxt) && ctxt->uid != inode_uid(inode)) {
-		ret = -EPERM;
-		goto out;
-	}
+	if (fuse4fs_want_check_owner(ff, ctxt) &&
+	    ctxt->uid != inode_uid(*inode))
+		return -EPERM;
 
 	/*
 	 * XXX: We should really check that the inode gid is not in /any/
@@ -2888,100 +2770,60 @@ static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
 	 * group.
 	 */
 	if (!fuse4fs_is_superuser(ff, ctxt)) {
-		ret = fuse4fs_in_file_group(ctxt, &inode);
+		ret = fuse4fs_in_file_group(ff, req, inode);
 		if (ret < 0)
-			goto out;
+			return ret;
 
 		if (!ret)
 			mode &= ~S_ISGID;
 	}
 
-	inode.i_mode &= ~0xFFF;
-	inode.i_mode |= mode & 0xFFF;
+	inode->i_mode &= ~0xFFF;
+	inode->i_mode |= mode & 0xFFF;
 
-	dbg_printf(ff, "%s: path=%s new_mode=0%o ino=%d\n", __func__,
-		   path, inode.i_mode, ino);
+	dbg_printf(ff, "%s: ino=%d new_mode=0%o\n",
+		   __func__, ino, inode->i_mode);
 
-	ret = update_ctime(fs, ino, &inode);
-	if (ret)
-		goto out;
-
-	err = fuse4fs_write_inode(fs, ino, &inode);
-	if (err) {
-		ret = translate_error(fs, ino, err);
-		goto out;
-	}
-
-out:
-	fuse4fs_finish(ff, ret);
-	return ret;
+	return 0;
 }
 
-static int op_chown(const char *path, uid_t owner, gid_t group,
-		    struct fuse_file_info *fi)
+static int fuse4fs_chown(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			 ext2_ino_t ino, const int to_set,
+			 const struct stat *attr,
+			 struct ext2_inode_large *inode)
 {
-	struct fuse_context *ctxt = fuse_get_context();
-	struct fuse4fs *ff = fuse4fs_get();
-	ext2_filsys fs;
-	errcode_t err;
-	ext2_ino_t ino;
-	struct ext2_inode_large inode;
+	uid_t owner = (to_set & FUSE_SET_ATTR_UID) ? attr->st_uid : (uid_t)~0;
+	gid_t group = (to_set & FUSE_SET_ATTR_GID) ? attr->st_gid : (gid_t)~0;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	fs = fuse4fs_start(ff);
-	ret = fuse4fs_file_ino(ff, path, fi, &ino);
-	if (ret)
-		goto out;
-	dbg_printf(ff, "%s: path=%s owner=%d group=%d ino=%d\n", __func__,
-		   path, owner, group, ino);
-
-	err = fuse4fs_read_inode(fs, ino, &inode);
-	if (err) {
-		ret = translate_error(fs, ino, err);
-		goto out;
-	}
+	dbg_printf(ff, "%s: ino=%d owner=%d group=%d\n",
+		   __func__, ino, owner, group);
 
-	ret = fuse4fs_iflags_access(ff, ino, EXT2_INODE(&inode), W_OK);
+	ret = fuse4fs_iflags_access(ff, ino, EXT2_INODE(inode), W_OK);
 	if (ret)
-		goto out;
+		return ret;
 
 	/* FUSE seems to feed us ~0 to mean "don't change" */
 	if (owner != (uid_t) ~0) {
 		/* Only root gets to change UID. */
 		if (fuse4fs_want_check_owner(ff, ctxt) &&
-		    !(inode_uid(inode) == ctxt->uid && owner == ctxt->uid)) {
-			ret = -EPERM;
-			goto out;
-		}
-		fuse4fs_set_uid(&inode, owner);
+		    !(inode_uid(*inode) == ctxt->uid && owner == ctxt->uid))
+			return -EPERM;
+
+		fuse4fs_set_uid(inode, owner);
 	}
 
 	if (group != (gid_t) ~0) {
 		/* Only root or the owner get to change GID. */
 		if (fuse4fs_want_check_owner(ff, ctxt) &&
-		    inode_uid(inode) != ctxt->uid) {
-			ret = -EPERM;
-			goto out;
-		}
+		    inode_uid(*inode) != ctxt->uid)
+			return -EPERM;
 
 		/* XXX: We /should/ check group membership but FUSE */
-		fuse4fs_set_gid(&inode, group);
+		fuse4fs_set_gid(inode, group);
 	}
 
-	ret = update_ctime(fs, ino, &inode);
-	if (ret)
-		goto out;
-
-	err = fuse4fs_write_inode(fs, ino, &inode);
-	if (err) {
-		ret = translate_error(fs, ino, err);
-		goto out;
-	}
-
-out:
-	fuse4fs_finish(ff, ret);
-	return ret;
+	return 0;
 }
 
 static int fuse4fs_punch_posteof(struct fuse4fs *ff, ext2_ino_t ino,
@@ -3056,32 +2898,6 @@ static int fuse4fs_truncate(struct fuse4fs *ff, ext2_ino_t ino, off_t new_size)
 	return 0;
 }
 
-static int op_truncate(const char *path, off_t len, struct fuse_file_info *fi)
-{
-	struct fuse4fs *ff = fuse4fs_get();
-	ext2_ino_t ino;
-	int ret = 0;
-
-	FUSE4FS_CHECK_CONTEXT(ff);
-	fuse4fs_start(ff);
-	ret = fuse4fs_file_ino(ff, path, fi, &ino);
-	if (ret)
-		goto out;
-	dbg_printf(ff, "%s: ino=%d len=%jd\n", __func__, ino, (intmax_t) len);
-
-	ret = fuse4fs_inum_access(ff, ino, W_OK);
-	if (ret)
-		goto out;
-
-	ret = fuse4fs_truncate(ff, ino, len);
-	if (ret)
-		goto out;
-
-out:
-	fuse4fs_finish(ff, ret);
-	return ret;
-}
-
 #ifdef __linux__
 static void detect_linux_executable_open(int kernel_flags, int *access_check,
 				  int *e2fs_open_flags)
@@ -3103,19 +2919,20 @@ static void detect_linux_executable_open(int kernel_flags, int *access_check,
 }
 #endif /* __linux__ */
 
-static int __op_open(struct fuse4fs *ff, const char *path,
-		     struct fuse_file_info *fp)
+static int fuse4fs_open_file(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			     ext2_ino_t ino, struct fuse_file_info *fp)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct fuse4fs_file_handle *file;
 	int check = 0, ret = 0;
 
-	dbg_printf(ff, "%s: path=%s oflags=0o%o\n", __func__, path, fp->flags);
+	dbg_printf(ff, "%s: ino=%d oflags=0o%o\n", __func__, ino, fp->flags);
 	err = ext2fs_get_mem(sizeof(*file), &file);
 	if (err)
 		return translate_error(fs, 0, err);
 	file->magic = FUSE4FS_FILE_MAGIC;
+	file->ino = ino;
 
 	file->open_flags = 0;
 	switch (fp->flags & O_ACCMODE) {
@@ -3144,14 +2961,7 @@ static int __op_open(struct fuse4fs *ff, const char *path,
 	if (fp->flags & O_CREAT)
 		file->open_flags |= EXT2_FILE_CREATE;
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &file->ino);
-	if (err || file->ino == 0) {
-		ret = translate_error(fs, 0, err);
-		goto out;
-	}
-	dbg_printf(ff, "%s: ino=%d\n", __func__, file->ino);
-
-	ret = fuse4fs_inum_access(ff, file->ino, check);
+	ret = fuse4fs_inum_access(ff, ctxt, file->ino, check);
 	if (ret) {
 		/*
 		 * In a regular (Linux) fs driver, the kernel will open
@@ -3163,7 +2973,7 @@ static int __op_open(struct fuse4fs *ff, const char *path,
 		 * also employ undocumented hacks (see above).
 		 */
 		if (check == R_OK) {
-			ret = fuse4fs_inum_access(ff, file->ino, X_OK);
+			ret = fuse4fs_inum_access(ff, ctxt, file->ino, X_OK);
 			if (ret)
 				goto out;
 			check = X_OK;
@@ -3186,34 +2996,48 @@ static int __op_open(struct fuse4fs *ff, const char *path,
 	return ret;
 }
 
-static int op_open(const char *path, struct fuse_file_info *fp)
+static void op_open(fuse_req_t req, fuse_ino_t fino, struct fuse_file_info *fp)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_ino_t ino;
 	int ret;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
 	fuse4fs_start(ff);
-	ret = __op_open(ff, path, fp);
+	ret = fuse4fs_open_file(ff, ctxt, ino, fp);
 	fuse4fs_finish(ff, ret);
-	return ret;
+
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_open(req, fp);
 }
 
-static int op_read(const char *path EXT2FS_ATTR((unused)), char *buf,
-		   size_t len, off_t offset,
-		   struct fuse_file_info *fp)
+static void op_read(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
+		    size_t len, off_t offset, struct fuse_file_info *fp)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = fuse4fs_get(req);
 	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	char *buf;
 	ext2_filsys fs;
 	ext2_file_t efp;
 	errcode_t err;
 	unsigned int got = 0;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	FUSE4FS_CHECK_HANDLE(ff, fh);
+	buf = calloc(len, sizeof(char));
+	if (!buf) {
+		fuse_reply_err(req, errno);
+		return;
+	}
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CHECK_HANDLE(req, fh);
 	dbg_printf(ff, "%s: ino=%d off=0x%llx len=0x%zx\n", __func__, fh->ino,
 		   (unsigned long long)offset, len);
+
 	fs = fuse4fs_start(ff);
 	err = ext2fs_file_open(fs, fh->ino, fh->open_flags, &efp);
 	if (err) {
@@ -3249,14 +3073,18 @@ static int op_read(const char *path EXT2FS_ATTR((unused)), char *buf,
 	}
 out:
 	fuse4fs_finish(ff, ret);
-	return got ? (int) got : ret;
+	if (got)
+		fuse_reply_buf(req, buf, got);
+	else
+		fuse_reply_err(req, -ret);
+	ext2fs_free_mem(&buf);
 }
 
-static int op_write(const char *path EXT2FS_ATTR((unused)),
-		    const char *buf, size_t len, off_t offset,
-		    struct fuse_file_info *fp)
+static void op_write(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
+		     const char *buf, size_t len, off_t offset,
+		     struct fuse_file_info *fp)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = fuse4fs_get(req);
 	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
 	ext2_filsys fs;
 	ext2_file_t efp;
@@ -3264,8 +3092,8 @@ static int op_write(const char *path EXT2FS_ATTR((unused)),
 	unsigned int got = 0;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	FUSE4FS_CHECK_HANDLE(ff, fh);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CHECK_HANDLE(req, fh);
 	dbg_printf(ff, "%s: ino=%d off=0x%llx len=0x%zx\n", __func__, fh->ino,
 		   (unsigned long long) offset, len);
 	fs = fuse4fs_start(ff);
@@ -3319,20 +3147,23 @@ static int op_write(const char *path EXT2FS_ATTR((unused)),
 
 out:
 	fuse4fs_finish(ff, ret);
-	return got ? (int) got : ret;
+	if (got)
+		fuse_reply_write(req, got);
+	else
+		fuse_reply_err(req, -ret);
 }
 
-static int op_release(const char *path EXT2FS_ATTR((unused)),
-		      struct fuse_file_info *fp)
+static void op_release(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
+		       struct fuse_file_info *fp)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = fuse4fs_get(req);
 	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
 	ext2_filsys fs;
 	errcode_t err;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	FUSE4FS_CHECK_HANDLE(ff, fh);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CHECK_HANDLE(req, fh);
 	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
 	fs = fuse4fs_start(ff);
 
@@ -3349,21 +3180,21 @@ static int op_release(const char *path EXT2FS_ATTR((unused)),
 
 	ext2fs_free_mem(&fh);
 
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 
-static int op_fsync(const char *path EXT2FS_ATTR((unused)),
-		    int datasync EXT2FS_ATTR((unused)),
-		    struct fuse_file_info *fp)
+static void op_fsync(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
+		     int datasync EXT2FS_ATTR((unused)),
+		     struct fuse_file_info *fp)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = fuse4fs_get(req);
 	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
 	ext2_filsys fs;
 	errcode_t err;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	FUSE4FS_CHECK_HANDLE(ff, fh);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CHECK_HANDLE(req, fh);
 	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
 	fs = fuse4fs_start(ff);
 	/* For now, flush everything, even if it's slow */
@@ -3374,22 +3205,24 @@ static int op_fsync(const char *path EXT2FS_ATTR((unused)),
 	}
 	fuse4fs_finish(ff, ret);
 
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 
-static int op_statfs(const char *path EXT2FS_ATTR((unused)),
-		     struct statvfs *buf)
+static void op_statfs(fuse_req_t req, fuse_ino_t fino)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct statvfs buf;
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	uint64_t fsid, *f;
+	ext2_ino_t ino;
 	blk64_t overhead, reserved, free;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: path=%s\n", __func__, path);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+	dbg_printf(ff, "%s: ino=%d\n", __func__, ino);
 	fs = fuse4fs_start(ff);
-	buf->f_bsize = fs->blocksize;
-	buf->f_frsize = 0;
+	buf.f_bsize = fs->blocksize;
+	buf.f_frsize = 0;
 
 	if (ff->minixdf)
 		overhead = 0;
@@ -3402,27 +3235,27 @@ static int op_statfs(const char *path EXT2FS_ATTR((unused)),
 		reserved = ext2fs_blocks_count(fs->super) / 10;
 	free = ext2fs_free_blocks_count(fs->super);
 
-	buf->f_blocks = ext2fs_blocks_count(fs->super) - overhead;
-	buf->f_bfree = free;
+	buf.f_blocks = ext2fs_blocks_count(fs->super) - overhead;
+	buf.f_bfree = free;
 	if (free < reserved)
-		buf->f_bavail = 0;
+		buf.f_bavail = 0;
 	else
-		buf->f_bavail = free - reserved;
-	buf->f_files = fs->super->s_inodes_count;
-	buf->f_ffree = fs->super->s_free_inodes_count;
-	buf->f_favail = fs->super->s_free_inodes_count;
+		buf.f_bavail = free - reserved;
+	buf.f_files = fs->super->s_inodes_count;
+	buf.f_ffree = fs->super->s_free_inodes_count;
+	buf.f_favail = fs->super->s_free_inodes_count;
 	f = (uint64_t *)fs->super->s_uuid;
 	fsid = *f;
 	f++;
 	fsid ^= *f;
-	buf->f_fsid = fsid;
-	buf->f_flag = 0;
+	buf.f_fsid = fsid;
+	buf.f_flag = 0;
 	if (ff->opstate != F4OP_WRITABLE)
-		buf->f_flag |= ST_RDONLY;
-	buf->f_namemax = EXT2_NAME_LEN;
+		buf.f_flag |= ST_RDONLY;
+	buf.f_namemax = EXT2_NAME_LEN;
 	fuse4fs_finish(ff, 0);
 
-	return 0;
+	fuse_reply_statfs(req, &buf);
 }
 
 static const char *valid_xattr_prefixes[] = {
@@ -3446,35 +3279,33 @@ static int validate_xattr_name(const char *name)
 	return 0;
 }
 
-static int op_getxattr(const char *path, const char *key, char *value,
-		       size_t len)
+static void op_getxattr(fuse_req_t req, fuse_ino_t fino, const char *key,
+			size_t len)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
-	void *ptr;
+	void *ptr = NULL;
 	size_t plen;
 	ext2_ino_t ino;
-	errcode_t err;
 	int ret = 0;
 
-	if (!validate_xattr_name(key))
-		return -ENODATA;
+	if (!validate_xattr_name(key)) {
+		fuse_reply_err(req, ENODATA);
+		return;
+	}
 
-	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
 	fs = fuse4fs_start(ff);
 	if (!ext2fs_has_feature_xattr(fs->super)) {
 		ret = -ENOTSUP;
 		goto out;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
-	if (err || ino == 0) {
-		ret = translate_error(fs, 0, err);
-		goto out;
-	}
-	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
+	dbg_printf(ff, "%s: ino=%d name='%s'\n", __func__, ino, key);
 
-	ret = fuse4fs_inum_access(ff, ino, R_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, ino, R_OK);
 	if (ret)
 		goto out;
 
@@ -3483,19 +3314,26 @@ static int op_getxattr(const char *path, const char *key, char *value,
 		goto out;
 
 	if (!len) {
+		/* Just tell us the length */
 		ret = plen;
 	} else if (len < plen) {
+		/* Caller's buffer wasn't big enough */
 		ret = -ERANGE;
 	} else {
-		memcpy(value, ptr, plen);
+		/* We have data */
 		ret = plen;
 	}
 
+out:
+	fuse4fs_finish(ff, ret);
+
+	if (ret < 0)
+		fuse_reply_err(req, -ret);
+	else if (!len)
+		fuse_reply_xattr(req, ret);
+	else
+		fuse_reply_buf(req, ptr, ret);
 	ext2fs_free_mem(&ptr);
-out:
-	fuse4fs_finish(ff, ret);
-
-	return ret;
 }
 
 static int count_buffer_space(char *name, char *value EXT2FS_ATTR((unused)),
@@ -3520,31 +3358,30 @@ static int copy_names(char *name, char *value EXT2FS_ATTR((unused)),
 	return 0;
 }
 
-static int op_listxattr(const char *path, char *names, size_t len)
+static void op_listxattr(fuse_req_t req, fuse_ino_t fino, size_t len)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	struct ext2_xattr_handle *h;
+	char *names = NULL;
+	char *next_name;
 	unsigned int bufsz;
 	ext2_ino_t ino;
 	errcode_t err;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
 	fs = fuse4fs_start(ff);
 	if (!ext2fs_has_feature_xattr(fs->super)) {
 		ret = -ENOTSUP;
 		goto out;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
-	if (err || ino == 0) {
-		ret = translate_error(fs, ino, err);
-		goto out;
-	}
 	dbg_printf(ff, "%s: ino=%d\n", __func__, ino);
 
-	ret = fuse4fs_inum_access(ff, ino, R_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, ino, R_OK);
 	if (ret)
 		goto out;
 
@@ -3569,21 +3406,28 @@ static int op_listxattr(const char *path, char *names, size_t len)
 	}
 
 	if (len == 0) {
-		ret = bufsz;
+		/* Just tell us the length */
 		goto out2;
 	} else if (len < bufsz) {
+		/* Caller's buffer wasn't big enough */
 		ret = -ERANGE;
 		goto out2;
 	}
 
 	/* Copy names out */
-	memset(names, 0, len);
-	err = ext2fs_xattrs_iterate(h, copy_names, &names);
+	names = calloc(len, sizeof(char));
+	if (!names) {
+		ret = translate_error(fs, ino, errno);
+		goto out2;
+	}
+	next_name = names;
+
+	err = ext2fs_xattrs_iterate(h, copy_names, &next_name);
 	if (err) {
 		ret = translate_error(fs, ino, err);
 		goto out2;
 	}
-	ret = bufsz;
+
 out2:
 	err = ext2fs_xattrs_close(&h);
 	if (err && !ret)
@@ -3591,41 +3435,47 @@ static int op_listxattr(const char *path, char *names, size_t len)
 out:
 	fuse4fs_finish(ff, ret);
 
-	return ret;
+	if (ret < 0)
+		fuse_reply_err(req, -ret);
+	else if (names)
+		fuse_reply_buf(req, names, bufsz);
+	else
+		fuse_reply_xattr(req, bufsz);
+	free(names);
 }
 
-static int op_setxattr(const char *path EXT2FS_ATTR((unused)),
-		       const char *key, const char *value,
-		       size_t len, int flags)
+static void op_setxattr(fuse_req_t req, fuse_ino_t fino, const char *key,
+			const char *value, size_t len, int flags)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	struct ext2_xattr_handle *h;
 	ext2_ino_t ino;
 	errcode_t err;
 	int ret = 0;
 
-	if (flags & ~(XATTR_CREATE | XATTR_REPLACE))
-		return -EOPNOTSUPP;
+	if (flags & ~(XATTR_CREATE | XATTR_REPLACE)) {
+		fuse_reply_err(req, EOPNOTSUPP);
+		return;
+	}
 
-	if (!validate_xattr_name(key))
-		return -EINVAL;
+	if (!validate_xattr_name(key)) {
+		fuse_reply_err(req, EINVAL);
+		return;
+	}
 
-	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
 	fs = fuse4fs_start(ff);
 	if (!ext2fs_has_feature_xattr(fs->super)) {
 		ret = -ENOTSUP;
 		goto out;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
-	if (err || ino == 0) {
-		ret = translate_error(fs, 0, err);
-		goto out;
-	}
-	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
+	dbg_printf(ff, "%s: ino=%d name='%s'\n", __func__, ino, key);
 
-	ret = fuse4fs_inum_access(ff, ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, ino, W_OK);
 	if (ret == -EACCES) {
 		ret = -EPERM;
 		goto out;
@@ -3682,13 +3532,13 @@ static int op_setxattr(const char *path EXT2FS_ATTR((unused)),
 		ret = translate_error(fs, ino, err);
 out:
 	fuse4fs_finish(ff, ret);
-
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 
-static int op_removexattr(const char *path, const char *key)
+static void op_removexattr(fuse_req_t req, fuse_ino_t fino, const char *key)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	struct ext2_xattr_handle *h;
 	void *buf;
@@ -3701,13 +3551,18 @@ static int op_removexattr(const char *path, const char *key)
 	 * Once in a while libfuse gives us a no-name xattr to delete as part
 	 * of clearing ACLs.  Just pretend we cleared them.
 	 */
-	if (key[0] == 0)
-		return 0;
+	if (key[0] == 0) {
+		fuse_reply_err(req, 0);
+		return;
+	}
 
-	if (!validate_xattr_name(key))
-		return -ENODATA;
+	if (!validate_xattr_name(key)) {
+		fuse_reply_err(req, ENODATA);
+		return;
+	}
 
-	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
 	fs = fuse4fs_start(ff);
 	if (!ext2fs_has_feature_xattr(fs->super)) {
 		ret = -ENOTSUP;
@@ -3719,14 +3574,9 @@ static int op_removexattr(const char *path, const char *key)
 		goto out;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
-	if (err || ino == 0) {
-		ret = translate_error(fs, 0, err);
-		goto out;
-	}
 	dbg_printf(ff, "%s: ino=%d name=%s\n", __func__, ino, key);
 
-	ret = fuse4fs_inum_access(ff, ino, W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, ino, W_OK);
 	if (ret)
 		goto out;
 
@@ -3776,24 +3626,26 @@ static int op_removexattr(const char *path, const char *key)
 		ret = translate_error(fs, ino, err);
 out:
 	fuse4fs_finish(ff, ret);
-
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 
 struct readdir_iter {
 	void *buf;
-	ext2_filsys fs;
-	fuse_fill_dir_t func;
+	size_t bufsz;
+	size_t bufused;
 
+	ext2_filsys fs;
 	struct fuse4fs *ff;
-	enum fuse_readdir_flags flags;
+	fuse_req_t req;
+
+	bool readdirplus;
 	unsigned int nr;
 	off_t startpos;
 	off_t dirpos;
 };
 
 static inline mode_t dirent_fmode(ext2_filsys fs,
-				   const struct ext2_dir_entry *dirent)
+				  const struct ext2_dir_entry *dirent)
 {
 	if (!ext2fs_has_feature_filetype(fs->super))
 		return 0;
@@ -3827,10 +3679,15 @@ static int op_readdir_iter(ext2_ino_t dir EXT2FS_ATTR((unused)),
 {
 	struct readdir_iter *i = data;
 	char namebuf[EXT2_NAME_LEN + 1];
-	struct stat stat = {
-		.st_ino = dirent->inode,
-		.st_mode = dirent_fmode(i->fs, dirent),
+	struct fuse4fs_stat fstat = {
+		.entry = {
+			.attr = {
+				.st_ino = dirent->inode,
+				.st_mode = dirent_fmode(i->fs, dirent),
+			},
+		},
 	};
+	size_t entrysize;
 	int ret;
 
 	i->dirpos++;
@@ -3838,48 +3695,67 @@ static int op_readdir_iter(ext2_ino_t dir EXT2FS_ATTR((unused)),
 		return 0;
 
 	dbg_printf(i->ff, "READDIR%s ino=%d %u offset=0x%llx\n",
-			i->flags == FUSE_READDIR_PLUS ? "PLUS" : "",
+			i->readdirplus ? "PLUS" : "",
 			dir,
 			i->nr++,
 			(unsigned long long)i->dirpos);
 
-	if (i->flags == FUSE_READDIR_PLUS) {
-		ret = stat_inode(i->fs, dirent->inode, &stat);
+	if (i->readdirplus) {
+		ret = fuse4fs_stat_inode(i->ff, dirent->inode, NULL, &fstat);
 		if (ret)
 			return DIRENT_ABORT;
 	}
 
 	memcpy(namebuf, dirent->name, dirent->name_len & 0xFF);
 	namebuf[dirent->name_len & 0xFF] = 0;
-	ret = i->func(i->buf, namebuf, &stat, i->dirpos , 0);
-	if (ret)
+
+	if (i->readdirplus) {
+		entrysize = fuse_add_direntry_plus(i->req, i->buf + i->bufused,
+						   i->bufsz - i->bufused,
+						   namebuf, &fstat.entry,
+						   i->dirpos);
+	} else {
+		entrysize = fuse_add_direntry(i->req, i->buf + i->bufused,
+					      i->bufsz - i->bufused, namebuf,
+					      &fstat.entry.attr, i->dirpos);
+	}
+	if (entrysize > i->bufsz - i->bufused) {
+		/* Buffer is full */
 		return DIRENT_ABORT;
+	}
 
+	i->bufused += entrysize;
 	return 0;
 }
 
-static int op_readdir(const char *path EXT2FS_ATTR((unused)), void *buf,
-		      fuse_fill_dir_t fill_func, off_t offset,
-		      struct fuse_file_info *fp, enum fuse_readdir_flags flags)
+static void __op_readdir(fuse_req_t req, fuse_ino_t fino, size_t size,
+			 off_t offset, bool plus, struct fuse_file_info *fp)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = fuse4fs_get(req);
 	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
 	errcode_t err;
 	struct readdir_iter i = {
 		.ff = ff,
+		.req = req,
 		.dirpos = 0,
 		.startpos = offset,
-		.flags = flags,
+		.readdirplus = plus,
+		.bufsz = size,
 	};
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	FUSE4FS_CHECK_HANDLE(ff, fh);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CHECK_HANDLE(req, fh);
 	dbg_printf(ff, "%s: ino=%d offset=0x%llx\n", __func__, fh->ino,
 			(unsigned long long)offset);
+
+	err = ext2fs_get_mem(size, &i.buf);
+	if (err) {
+		ret = translate_error(i.fs, fh->ino, err);
+		goto out;
+	}
+
 	i.fs = fuse4fs_start(ff);
-	i.buf = buf;
-	i.func = fill_func;
 	err = ext2fs_dir_iterate2(i.fs, fh->ino, 0, NULL, op_readdir_iter, &i);
 	if (err) {
 		ret = translate_error(i.fs, fh->ino, err);
@@ -3893,64 +3769,66 @@ static int op_readdir(const char *path EXT2FS_ATTR((unused)), void *buf,
 	}
 out:
 	fuse4fs_finish(ff, ret);
-	return ret;
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_buf(req, i.buf, i.bufused);
+
+	ext2fs_free_mem(&i.buf);
+}
+
+static void op_readdir(fuse_req_t req, fuse_ino_t fino, size_t size,
+		       off_t offset, struct fuse_file_info *fp)
+{
+	__op_readdir(req, fino, size, offset, false, fp);
+}
+
+static void op_readdirplus(fuse_req_t req, fuse_ino_t fino, size_t size,
+			   off_t offset, struct fuse_file_info *fp)
+{
+	__op_readdir(req, fino, size, offset, true, fp);
 }
 
-static int op_access(const char *path, int mask)
+static void op_access(fuse_req_t req, fuse_ino_t fino, int mask)
 {
-	struct fuse4fs *ff = fuse4fs_get();
-	ext2_filsys fs;
-	errcode_t err;
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_ino_t ino;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: path=%s mask=0x%x\n", __func__, path, mask);
-	fs = fuse4fs_start(ff);
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
-	if (err || ino == 0) {
-		ret = translate_error(fs, 0, err);
-		goto out;
-	}
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+	dbg_printf(ff, "%s: ino=%d mask=0x%x\n",
+		   __func__, ino, mask);
+	fuse4fs_start(ff);
 
-	ret = fuse4fs_inum_access(ff, ino, mask);
+	ret = fuse4fs_inum_access(ff, ctxt, ino, mask);
 	if (ret)
 		goto out;
 
 out:
 	fuse4fs_finish(ff, ret);
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 
-static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
+static void op_create(fuse_req_t req, fuse_ino_t fino, const char *name,
+		      mode_t mode, struct fuse_file_info *fp)
 {
-	struct fuse_context *ctxt = fuse_get_context();
-	struct fuse4fs *ff = fuse4fs_get();
+	struct ext2_inode_large inode;
+	struct fuse4fs_stat fstat;
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	ext2_ino_t parent, child;
-	char *temp_path;
 	errcode_t err;
-	char *node_name, a;
 	int filetype;
-	struct ext2_inode_large inode;
 	gid_t gid;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	dbg_printf(ff, "%s: path=%s mode=0%o\n", __func__, path, mode);
-	temp_path = strdup(path);
-	if (!temp_path) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name = strrchr(temp_path, '/');
-	if (!node_name) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	node_name++;
-	a = *node_name;
-	*node_name = 0;
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &parent, fino);
+	dbg_printf(ff, "%s: parent=%d name='%s' mode=0%o\n",
+		   __func__, parent, name, mode);
 
 	fs = fuse4fs_start(ff);
 	if (!fuse4fs_can_allocate(ff, 1)) {
@@ -3958,23 +3836,14 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 		goto out2;
 	}
 
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, temp_path,
-			   &parent);
-	if (err) {
-		ret = translate_error(fs, 0, err);
-		goto out2;
-	}
-
-	ret = fuse4fs_inum_access(ff, parent, A_OK | W_OK);
+	ret = fuse4fs_inum_access(ff, ctxt, parent, A_OK | W_OK);
 	if (ret)
 		goto out2;
 
-	err = fuse4fs_new_child_gid(ff, parent, &gid, NULL);
+	err = fuse4fs_new_child_gid(ff, ctxt, parent, &gid, NULL);
 	if (err)
 		goto out2;
 
-	*node_name = a;
-
 	filetype = ext2_file_type(mode);
 
 	err = ext2fs_new_inode(fs, parent, mode, 0, &child);
@@ -3983,9 +3852,9 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 		goto out2;
 	}
 
-	dbg_printf(ff, "%s: creating ino=%d/name=%s in dir=%d\n", __func__, child,
-		   node_name, parent);
-	err = ext2fs_link(fs, parent, node_name, child,
+	dbg_printf(ff, "%s: creating dir=%d name='%s' child=%d\n",
+		   __func__, parent, name, child);
+	err = ext2fs_link(fs, parent, name, child,
 			  filetype | EXT2FS_LINK_EXPAND);
 	if (err) {
 		ret = translate_error(fs, parent, err);
@@ -4037,7 +3906,7 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 		goto out2;
 
 	fp->flags &= ~O_TRUNC;
-	ret = __op_open(ff, path, fp);
+	ret = fuse4fs_open_file(ff, ctxt, child, fp);
 	if (ret)
 		goto out2;
 
@@ -4045,44 +3914,152 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 	if (ret)
 		goto out2;
 
+	ret = fuse4fs_stat_inode(ff, child, NULL, &fstat);
+	if (ret)
+		goto out2;
+
 out2:
 	fuse4fs_finish(ff, ret);
-out:
-	free(temp_path);
-	return ret;
+
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_create(req, &fstat.entry, fp);
+}
+
+enum fuse4fs_time_action {
+	TA_NOW,		/* set to current time */
+	TA_OMIT,	/* do not set timestamp */
+	TA_THIS,	/* set to specific timestamp */
+};
+
+static inline const char *
+fuse4fs_time_action_string(enum fuse4fs_time_action act)
+{
+	switch (act) {
+	case TA_NOW:
+		return "now";
+	case TA_OMIT:
+		return "omit";
+	case TA_THIS:
+		return "specific";
+	}
+	return NULL; /* shut up gcc */
 }
 
-static int op_utimens(const char *path, const struct timespec ctv[2],
-		      struct fuse_file_info *fi)
+static int fuse4fs_utimens(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			   ext2_ino_t ino, const int to_set,
+			   const struct stat *attr,
+			   struct ext2_inode_large *inode)
 {
-	struct fuse4fs *ff = fuse4fs_get();
-	struct timespec tv[2];
-	ext2_filsys fs;
-	errcode_t err;
-	ext2_ino_t ino;
-	struct ext2_inode_large inode;
+	enum fuse4fs_time_action aact = TA_OMIT;
+	enum fuse4fs_time_action mact = TA_OMIT;
+	struct timespec atime = { };
+	struct timespec mtime = { };
+	struct timespec now = { };
 	int access = W_OK;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	fs = fuse4fs_start(ff);
-	ret = fuse4fs_file_ino(ff, path, fi, &ino);
-	if (ret)
-		goto out;
-	dbg_printf(ff, "%s: ino=%d atime=%lld.%ld mtime=%lld.%ld\n", __func__,
-			ino,
-			(long long int)ctv[0].tv_sec, ctv[0].tv_nsec,
-			(long long int)ctv[1].tv_sec, ctv[1].tv_nsec);
+	if (to_set & (FUSE_SET_ATTR_ATIME_NOW | FUSE_SET_ATTR_MTIME_NOW))
+		get_now(&now);
+
+	if (to_set & FUSE_SET_ATTR_ATIME_NOW) {
+		atime = now;
+		aact = TA_NOW;
+	} else if (to_set & FUSE_SET_ATTR_ATIME) {
+#if HAVE_STRUCT_STAT_ST_ATIM
+		atime = attr->st_atim;
+#else
+		atime.tv_sec = attr->st_atime;
+#endif
+		aact = TA_THIS;
+	}
+
+	if (to_set & FUSE_SET_ATTR_MTIME_NOW) {
+		mtime = now;
+		mact = TA_NOW;
+	} else if (to_set & FUSE_SET_ATTR_MTIME) {
+#if HAVE_STRUCT_STAT_ST_ATIM
+		mtime = attr->st_mtim;
+#else
+		mtime.tv_sec = attr->st_mtime;
+#endif
+		mact = TA_THIS;
+	}
+
+	dbg_printf(ff, "%s: ino=%d atime=%s:%lld.%ld mtime=%s:%lld.%ld\n",
+		   __func__, ino, fuse4fs_time_action_string(aact),
+		   (long long int)atime.tv_sec, atime.tv_nsec,
+		   fuse4fs_time_action_string(mact),
+		   (long long int)mtime.tv_sec, mtime.tv_nsec);
 
 	/*
 	 * ext4 allows timestamp updates of append-only files but only if we're
 	 * setting to current time
 	 */
-	if (ctv[0].tv_nsec == UTIME_NOW && ctv[1].tv_nsec == UTIME_NOW)
+	if (aact == TA_NOW && mact == TA_NOW)
 		access |= A_OK;
-	ret = fuse4fs_inum_access(ff, ino, access);
+	ret = fuse4fs_inum_access(ff, ctxt, ino, access);
 	if (ret)
+		return ret;
+
+	if (aact != TA_OMIT)
+		EXT4_INODE_SET_XTIME(i_atime, &atime, inode);
+	if (mact != TA_OMIT)
+		EXT4_INODE_SET_XTIME(i_mtime, &mtime, inode);
+
+	return 0;
+}
+
+static int fuse4fs_setsize(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			   ext2_ino_t ino, off_t new_size,
+			   struct ext2_inode_large *inode)
+{
+	errcode_t err;
+	int ret;
+
+	/* Write inode because truncate makes its own copy */
+	err = fuse4fs_write_inode(ff->fs, ino, inode);
+	if (err)
+		return translate_error(ff->fs, ino, err);
+
+	ret = fuse4fs_inum_access(ff, ctxt, ino, W_OK);
+	if (ret)
+		return ret;
+
+	ret = fuse4fs_truncate(ff, ino, new_size);
+	if (ret)
+		return ret;
+
+	/* Re-read inode after truncate */
+	err = fuse4fs_read_inode(ff->fs, ino, inode);
+	if (err)
+		return translate_error(ff->fs, ino, err);
+
+	return 0;
+}
+
+static void op_setattr(fuse_req_t req, fuse_ino_t fino, struct stat *attr,
+		       int to_set, struct fuse_file_info *fi EXT2FS_ATTR((unused)))
+{
+	struct ext2_inode_large inode;
+	struct fuse4fs_stat fstat;
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_filsys fs;
+	ext2_ino_t ino;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+	dbg_printf(ff, "%s: ino=%d to_set=0x%x\n", __func__, ino, to_set);
+	fs = fuse4fs_start(ff);
+
+	if (!fuse4fs_is_writeable(ff)) {
+		ret = -EROFS;
 		goto out;
+	}
 
 	err = fuse4fs_read_inode(fs, ino, &inode);
 	if (err) {
@@ -4090,20 +4067,35 @@ static int op_utimens(const char *path, const struct timespec ctv[2],
 		goto out;
 	}
 
-	tv[0] = ctv[0];
-	tv[1] = ctv[1];
-#ifdef UTIME_NOW
-	if (tv[0].tv_nsec == UTIME_NOW)
-		get_now(tv);
-	if (tv[1].tv_nsec == UTIME_NOW)
-		get_now(tv + 1);
-#endif /* UTIME_NOW */
-#ifdef UTIME_OMIT
-	if (tv[0].tv_nsec != UTIME_OMIT)
-		EXT4_INODE_SET_XTIME(i_atime, &tv[0], &inode);
-	if (tv[1].tv_nsec != UTIME_OMIT)
-		EXT4_INODE_SET_XTIME(i_mtime, &tv[1], &inode);
-#endif /* UTIME_OMIT */
+	/* Handle mode change using helper */
+	if (to_set & FUSE_SET_ATTR_MODE) {
+		ret = fuse4fs_chmod(ff, req, ino, attr->st_mode, &inode);
+		if (ret)
+			goto out;
+	}
+
+	/* Handle owner/group change using helper */
+	if (to_set & (FUSE_SET_ATTR_UID | FUSE_SET_ATTR_GID)) {
+		ret = fuse4fs_chown(ff, ctxt, ino, to_set, attr, &inode);
+		if (ret)
+			goto out;
+	}
+
+	/* Handle size change using helper */
+	if (to_set & FUSE_SET_ATTR_SIZE) {
+		ret = fuse4fs_setsize(ff, ctxt, ino, attr->st_size, &inode);
+		if (ret)
+			goto out;
+	}
+
+	/* Handle time changes using helper */
+	if (to_set & (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME)) {
+		ret = fuse4fs_utimens(ff, ctxt, ino, to_set, attr, &inode);
+		if (ret)
+			goto out;
+	}
+
+	/* Update ctime for any attribute change */
 	ret = update_ctime(fs, ino, &inode);
 	if (ret)
 		goto out;
@@ -4114,9 +4106,17 @@ static int op_utimens(const char *path, const struct timespec ctv[2],
 		goto out;
 	}
 
+	/* Get updated stat info to return */
+	ret = fuse4fs_stat_inode(ff, ino, &inode, &fstat);
+
 out:
 	fuse4fs_finish(ff, ret);
-	return ret;
+
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_attr(req, &fstat.entry.attr,
+				fstat.entry.attr_timeout);
 }
 
 #define FUSE4FS_MODIFIABLE_IFLAGS \
@@ -4135,32 +4135,38 @@ static inline int set_iflags(struct ext2_inode_large *inode, __u32 iflags)
 
 #ifdef SUPPORT_I_FLAGS
 static int ioctl_getflags(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
-			  void *data)
+			  __u32 *outdata, size_t *outsize)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct ext2_inode_large inode;
 
+	if (*outsize < sizeof(__u32))
+		return -EFAULT;
+
 	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
 	err = fuse4fs_read_inode(fs, fh->ino, &inode);
 	if (err)
 		return translate_error(fs, fh->ino, err);
 
-	*(__u32 *)data = inode.i_flags & EXT2_FL_USER_VISIBLE;
+	*outdata = inode.i_flags & EXT2_FL_USER_VISIBLE;
+	*outsize = sizeof(__u32);
 	return 0;
 }
 
-static int ioctl_setflags(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
-			  void *data)
+static int ioctl_setflags(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			  struct fuse4fs_file_handle *fh, const __u32 *indata,
+			  size_t insize)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct ext2_inode_large inode;
 	int ret;
-	__u32 flags = *(__u32 *)data;
-	struct fuse_context *ctxt = fuse_get_context();
 
-	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	if (insize < sizeof(__u32))
+		return -EFAULT;
+
+	dbg_printf(ff, "%s: ino=%d iflags=0x%x\n", __func__, fh->ino, *indata);
 	err = fuse4fs_read_inode(fs, fh->ino, &inode);
 	if (err)
 		return translate_error(fs, fh->ino, err);
@@ -4168,7 +4174,7 @@ static int ioctl_setflags(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 	if (fuse4fs_want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
 		return -EPERM;
 
-	ret = set_iflags(&inode, flags);
+	ret = set_iflags(&inode, *indata);
 	if (ret)
 		return ret;
 
@@ -4184,32 +4190,38 @@ static int ioctl_setflags(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 }
 
 static int ioctl_getversion(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
-			    void *data)
+			    __u32 *outdata, size_t *outsize)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct ext2_inode_large inode;
 
+	if (*outsize < sizeof(__u32))
+		return -EFAULT;
+
 	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
 	err = fuse4fs_read_inode(fs, fh->ino, &inode);
 	if (err)
 		return translate_error(fs, fh->ino, err);
 
-	*(__u32 *)data = inode.i_generation;
+	*outdata = inode.i_generation;
+	*outsize = sizeof(__u32);
 	return 0;
 }
 
-static int ioctl_setversion(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
-			    void *data)
+static int ioctl_setversion(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			    struct fuse4fs_file_handle *fh, const __u32 *indata,
+			    size_t insize)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct ext2_inode_large inode;
 	int ret;
-	__u32 generation = *(__u32 *)data;
-	struct fuse_context *ctxt = fuse_get_context();
 
-	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	if (insize < sizeof(__u32))
+		return -EFAULT;
+
+	dbg_printf(ff, "%s: ino=%d generation=%d\n", __func__, fh->ino, *indata);
 	err = fuse4fs_read_inode(fs, fh->ino, &inode);
 	if (err)
 		return translate_error(fs, fh->ino, err);
@@ -4217,7 +4229,7 @@ static int ioctl_setversion(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 	if (fuse4fs_want_check_owner(ff, ctxt) && inode_uid(inode) != ctxt->uid)
 		return -EPERM;
 
-	inode.i_generation = generation;
+	inode.i_generation = *indata;
 
 	ret = update_ctime(fs, fh->ino, &inode);
 	if (ret)
@@ -4254,14 +4266,16 @@ static __u32 iflags_to_fsxflags(__u32 iflags)
 }
 
 static int ioctl_fsgetxattr(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
-			    void *data)
+			    struct fsxattr *fsx, size_t *outsize)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct ext2_inode_large inode;
-	struct fsxattr *fsx = data;
 	unsigned int inode_size;
 
+	if (*outsize < sizeof(struct fsxattr))
+		return -EFAULT;
+
 	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
 	err = fuse4fs_read_inode(fs, fh->ino, &inode);
 	if (err)
@@ -4272,6 +4286,7 @@ static int ioctl_fsgetxattr(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 	if (ext2fs_inode_includes(inode_size, i_projid))
 		fsx->fsx_projid = inode_projid(inode);
 	fsx->fsx_xflags = iflags_to_fsxflags(inode.i_flags);
+	*outsize = sizeof(struct fsxattr);
 	return 0;
 }
 
@@ -4323,17 +4338,19 @@ static inline int set_xflags(struct ext2_inode_large *inode, __u32 xflags)
 	return 0;
 }
 
-static int ioctl_fssetxattr(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
-			    void *data)
+static int ioctl_fssetxattr(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			    struct fuse4fs_file_handle *fh,
+			    const struct fsxattr *fsx, size_t insize)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct ext2_inode_large inode;
 	int ret;
-	struct fuse_context *ctxt = fuse_get_context();
-	struct fsxattr *fsx = data;
 	unsigned int inode_size;
 
+	if (insize < sizeof(struct fsxattr))
+		return -EFAULT;
+
 	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
 	err = fuse4fs_read_inode(fs, fh->ino, &inode);
 	if (err)
@@ -4364,17 +4381,24 @@ static int ioctl_fssetxattr(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 
 #ifdef FITRIM
 static int ioctl_fitrim(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
-			void *data)
+			const struct fstrim_range *fr_in, size_t insize,
+			struct fstrim_range *fr, size_t *outsize)
 {
 	ext2_filsys fs = ff->fs;
-	struct fstrim_range *fr = data;
 	blk64_t start, end, max_blocks, b, cleared, minlen;
 	blk64_t max_blks = ext2fs_blocks_count(fs->super);
 	errcode_t err = 0;
 
+	if (insize < sizeof(struct fstrim_range))
+		return -EFAULT;
+
+	if (*outsize < sizeof(struct fstrim_range))
+		return -EFAULT;
+
 	if (!fuse4fs_is_writeable(ff))
 		return -EROFS;
 
+	memcpy(fr, fr_in, sizeof(*fr));
 	start = FUSE4FS_B_TO_FSBT(ff, fr->start);
 	if (fr->len == -1ULL)
 		end = -1ULL;
@@ -4453,6 +4477,7 @@ static int ioctl_fitrim(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 
 out:
 	fr->len = FUSE4FS_FSB_TO_B(ff, cleared);
+	*outsize = sizeof(struct fstrim_range);
 	dbg_printf(ff, "%s: len=%llu err=%ld\n", __func__, fr->len, err);
 	return err;
 }
@@ -4462,10 +4487,10 @@ static int ioctl_fitrim(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 # define EXT4_IOC_SHUTDOWN	_IOR('X', 125, __u32)
 #endif
 
-static int ioctl_shutdown(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
-			  void *data)
+static int ioctl_shutdown(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
+			  struct fuse4fs_file_handle *fh, const void *indata,
+			  size_t insize)
 {
-	struct fuse_context *ctxt = fuse_get_context();
 	ext2_filsys fs = ff->fs;
 
 	if (!fuse4fs_is_superuser(ff, ctxt))
@@ -4485,49 +4510,61 @@ static int ioctl_shutdown(struct fuse4fs *ff, struct fuse4fs_file_handle *fh,
 	return 0;
 }
 
-static int op_ioctl(const char *path EXT2FS_ATTR((unused)),
-		    unsigned int cmd,
-		    void *arg EXT2FS_ATTR((unused)),
-		    struct fuse_file_info *fp,
-		    unsigned int flags EXT2FS_ATTR((unused)), void *data)
+static void op_ioctl(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
+		     unsigned int cmd,
+		     void *arg EXT2FS_ATTR((unused)),
+		     struct fuse_file_info *fp,
+		     unsigned int flags EXT2FS_ATTR((unused)),
+		     const void *indata, size_t insize,
+		     size_t outsize)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	struct fuse4fs *ff = fuse4fs_get(req);
 	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
+	void *outdata = NULL;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	FUSE4FS_CHECK_HANDLE(ff, fh);
+	if (outsize > 0) {
+		outdata = calloc(outsize, sizeof(char));
+		if (!outdata) {
+			fuse_reply_err(req, errno);
+			return;
+		}
+	}
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CHECK_HANDLE(req, fh);
 	fuse4fs_start(ff);
 	switch ((unsigned long) cmd) {
 #ifdef SUPPORT_I_FLAGS
 	case EXT2_IOC_GETFLAGS:
-		ret = ioctl_getflags(ff, fh, data);
+		ret = ioctl_getflags(ff, fh, outdata, &outsize);
 		break;
 	case EXT2_IOC_SETFLAGS:
-		ret = ioctl_setflags(ff, fh, data);
+		ret = ioctl_setflags(ff, ctxt, fh, indata, insize);
 		break;
 	case EXT2_IOC_GETVERSION:
-		ret = ioctl_getversion(ff, fh, data);
+		ret = ioctl_getversion(ff, fh, outdata, &outsize);
 		break;
 	case EXT2_IOC_SETVERSION:
-		ret = ioctl_setversion(ff, fh, data);
+		ret = ioctl_setversion(ff, ctxt, fh, indata, insize);
 		break;
 #endif
 #ifdef FS_IOC_FSGETXATTR
 	case FS_IOC_FSGETXATTR:
-		ret = ioctl_fsgetxattr(ff, fh, data);
+		ret = ioctl_fsgetxattr(ff, fh, outdata, &outsize);
 		break;
 	case FS_IOC_FSSETXATTR:
-		ret = ioctl_fssetxattr(ff, fh, data);
+		ret = ioctl_fssetxattr(ff, ctxt, fh, indata, insize);
 		break;
 #endif
 #ifdef FITRIM
 	case FITRIM:
-		ret = ioctl_fitrim(ff, fh, data);
+		ret = ioctl_fitrim(ff, fh, indata, insize, outdata, &outsize);
 		break;
 #endif
 	case EXT4_IOC_SHUTDOWN:
-		ret = ioctl_shutdown(ff, fh, data);
+		ret = ioctl_shutdown(ff, ctxt, fh, indata, insize);
 		break;
 	default:
 		dbg_printf(ff, "%s: Unknown ioctl %d\n", __func__, cmd);
@@ -4535,28 +4572,29 @@ static int op_ioctl(const char *path EXT2FS_ATTR((unused)),
 	}
 	fuse4fs_finish(ff, ret);
 
-	return ret;
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_ioctl(req, 0, outdata, outsize);
+	free(outdata);
 }
 
-static int op_bmap(const char *path, size_t blocksize EXT2FS_ATTR((unused)),
-		   uint64_t *idx)
+static void op_bmap(fuse_req_t req, fuse_ino_t fino,
+		    size_t blocksize EXT2FS_ATTR((unused)), uint64_t idx)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
 	ext2_ino_t ino;
+	blk64_t blkno;
 	errcode_t err;
 	int ret = 0;
 
-	FUSE4FS_CHECK_CONTEXT(ff);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
 	fs = fuse4fs_start(ff);
-	err = ext2fs_namei(fs, EXT2_ROOT_INO, EXT2_ROOT_INO, path, &ino);
-	if (err) {
-		ret = translate_error(fs, 0, err);
-		goto out;
-	}
-	dbg_printf(ff, "%s: ino=%d blk=%"PRIu64"\n", __func__, ino, *idx);
+	dbg_printf(ff, "%s: ino=%d blk=%"PRIu64"\n", __func__, ino, idx);
 
-	err = ext2fs_bmap2(fs, ino, NULL, NULL, 0, *idx, 0, (blk64_t *)idx);
+	err = ext2fs_bmap2(fs, ino, NULL, NULL, 0, idx, 0, &blkno);
 	if (err) {
 		ret = translate_error(fs, ino, err);
 		goto out;
@@ -4564,7 +4602,10 @@ static int op_bmap(const char *path, size_t blocksize EXT2FS_ATTR((unused)),
 
 out:
 	fuse4fs_finish(ff, ret);
-	return ret;
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_bmap(req, blkno);
 }
 
 #ifdef SUPPORT_FALLOCATE
@@ -4807,20 +4848,22 @@ static int fuse4fs_zero_range(struct fuse4fs *ff,
 	return ret;
 }
 
-static int op_fallocate(const char *path EXT2FS_ATTR((unused)), int mode,
-			off_t offset, off_t len,
-			struct fuse_file_info *fp)
+static void op_fallocate(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
+			 int mode, off_t offset, off_t len,
+			 struct fuse_file_info *fp)
 {
-	struct fuse4fs *ff = fuse4fs_get();
+	struct fuse4fs *ff = fuse4fs_get(req);
 	struct fuse4fs_file_handle *fh = fuse4fs_get_handle(fp);
 	int ret;
 
 	/* Catch unknown flags */
-	if (mode & ~(FL_ZERO_RANGE_FLAG | FL_PUNCH_HOLE_FLAG | FL_KEEP_SIZE_FLAG))
-		return -EOPNOTSUPP;
+	if (mode & ~(FL_ZERO_RANGE_FLAG | FL_PUNCH_HOLE_FLAG | FL_KEEP_SIZE_FLAG)) {
+		fuse_reply_err(req, EOPNOTSUPP);
+		return;
+	}
 
-	FUSE4FS_CHECK_CONTEXT(ff);
-	FUSE4FS_CHECK_HANDLE(ff, fh);
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CHECK_HANDLE(req, fh);
 	fuse4fs_start(ff);
 	if (!fuse4fs_is_writeable(ff)) {
 		ret = -EROFS;
@@ -4840,12 +4883,13 @@ static int op_fallocate(const char *path EXT2FS_ATTR((unused)), int mode,
 		ret = fuse4fs_allocate_range(ff, fh, mode, offset, len);
 out:
 	fuse4fs_finish(ff, ret);
-
-	return ret;
+	fuse_reply_err(req, -ret);
 }
 #endif /* SUPPORT_FALLOCATE */
 
-static struct fuse_operations fs_ops = {
+static struct fuse_lowlevel_ops fs_ops = {
+	.lookup = op_lookup,
+	.setattr = op_setattr,
 	.init = op_init,
 	.destroy = op_destroy,
 	.getattr = op_getattr,
@@ -4857,9 +4901,6 @@ static struct fuse_operations fs_ops = {
 	.symlink = op_symlink,
 	.rename = op_rename,
 	.link = op_link,
-	.chmod = op_chmod,
-	.chown = op_chown,
-	.truncate = op_truncate,
 	.open = op_open,
 	.read = op_read,
 	.write = op_write,
@@ -4872,11 +4913,11 @@ static struct fuse_operations fs_ops = {
 	.removexattr = op_removexattr,
 	.opendir = op_open,
 	.readdir = op_readdir,
+	.readdirplus = op_readdirplus,
 	.releasedir = op_release,
 	.fsyncdir = op_fsync,
 	.access = op_access,
 	.create = op_create,
-	.utimens = op_utimens,
 	.bmap = op_bmap,
 #ifdef SUPERFLUOUS
 	.lock = op_lock,
@@ -5025,8 +5066,8 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
 	"\n",
 			outargs->argv[0]);
 		if (key == FUSE4FS_HELPFULL) {
-			fuse_opt_add_arg(outargs, "-h");
-			fuse_main(outargs->argc, outargs->argv, &fs_ops, NULL);
+			printf("FUSE options:\n");
+			fuse_cmdline_help();
 		} else {
 			fprintf(stderr, "Try --helpfull to get a list of "
 				"all flags, including the FUSE options.\n");
@@ -5036,8 +5077,7 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
 	case FUSE4FS_VERSION:
 		fprintf(stderr, "fuse4fs %s (%s)\n", E2FSPROGS_VERSION,
 			E2FSPROGS_DATE);
-		fuse_opt_add_arg(outargs, "--version");
-		fuse_main(outargs->argc, outargs->argv, &fs_ops, NULL);
+		fprintf(stderr, "FUSE library version %s\n", fuse_pkgversion());
 		exit(0);
 	}
 	return 1;
@@ -5106,6 +5146,107 @@ static void fuse4fs_com_err_proc(const char *whoami, errcode_t code,
 	fflush(stderr);
 }
 
+static int fuse4fs_main(struct fuse_args *args, struct fuse4fs *ff)
+{
+	struct fuse_cmdline_opts opts;
+	struct fuse_session *se;
+	struct fuse_loop_config *loop_config = NULL;
+	int ret;
+
+	if (fuse_parse_cmdline(args, &opts) != 0) {
+		ret = 1;
+		goto out;
+	}
+
+	if (ff->debug)
+		opts.debug = true;
+
+	if (opts.show_help) {
+		fuse_cmdline_help();
+		ret = 0;
+		goto out_free_opts;
+	}
+
+	if (opts.show_version) {
+		printf("FUSE library version %s\n", fuse_pkgversion());
+		ret = 0;
+		goto out_free_opts;
+	}
+
+	if (!opts.mountpoint) {
+		fprintf(stderr, "error: no mountpoint specified\n");
+		ret = 2;
+		goto out_free_opts;
+	}
+
+	se = fuse_session_new(args, &fs_ops, sizeof(fs_ops), ff);
+	if (se == NULL) {
+		ret = 3;
+		goto out_free_opts;
+	}
+	ff->fuse = se;
+
+	if (fuse_session_mount(se, opts.mountpoint) != 0) {
+		ret = 4;
+		goto out_destroy_session;
+	}
+
+	if (fuse_daemonize(opts.foreground) != 0) {
+		ret = 5;
+		goto out_unmount;
+	}
+
+	/*
+	 * Configure logging a second time, because libfuse might have
+	 * redirected std{out,err} as part of daemonization.  If this fails,
+	 * give up and move on.
+	 */
+	fuse4fs_setup_logging(ff);
+	if (ff->logfd >= 0)
+		close(ff->logfd);
+	ff->logfd = -1;
+
+	if (fuse_set_signal_handlers(se) != 0) {
+		ret = 6;
+		goto out_unmount;
+	}
+
+	loop_config = fuse_loop_cfg_create();
+	if (loop_config == NULL) {
+		ret = 7;
+		goto out_remove_signal_handlers;
+	}
+
+	/*
+	 * Since there's a Big Kernel Lock around all the libext2fs code, we
+	 * only need to start four threads -- one to decode a request, another
+	 * to do the filesystem work, a third to transmit the reply, and a
+	 * fourth to handle fuse notifications.
+	 */
+	fuse_loop_cfg_set_clone_fd(loop_config, opts.clone_fd);
+	fuse_loop_cfg_set_idle_threads(loop_config, opts.max_idle_threads);
+	fuse_loop_cfg_set_max_threads(loop_config, 4);
+
+	if (fuse_session_loop_mt(se, loop_config) != 0) {
+		ret = 8;
+		goto out_loopcfg;
+	}
+
+out_loopcfg:
+	fuse_loop_cfg_destroy(loop_config);
+out_remove_signal_handlers:
+	fuse_remove_signal_handlers(se);
+out_unmount:
+	fuse_session_unmount(se);
+out_destroy_session:
+	ff->fuse = NULL;
+	fuse_session_destroy(se);
+out_free_opts:
+	free(opts.mountpoint);
+out:
+	return ret;
+}
+
 int main(int argc, char *argv[])
 {
 	struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
@@ -5247,8 +5388,7 @@ int main(int argc, char *argv[])
 	get_random_bytes(&fctx.next_generation, sizeof(unsigned int));
 
 	/* Set up default fuse parameters */
-	snprintf(extra_args, BUFSIZ, "-okernel_cache,subtype=%s,"
-		 "fsname=%s,attr_timeout=0",
+	snprintf(extra_args, BUFSIZ, "-osubtype=%s,fsname=%s",
 		 get_subtype(argv[0]),
 		 fctx.device);
 	if (fctx.no_default_opts == 0)
@@ -5276,14 +5416,6 @@ int main(int argc, char *argv[])
  "-oallow_other,default_permissions,suid,dev");
 	}
 
-	/*
-	 * Since there's a Big Kernel Lock around all the libext2fs code, we
-	 * only need to start four threads -- one to decode a request, another
-	 * to do the filesystem work, a third to transmit the reply, and a
-	 * fourth to handle fuse notifications.
-	 */
-	fuse_opt_insert_arg(&args, 1, "-omax_threads=4");
-
 	if (fctx.debug) {
 		int	i;
 
@@ -5295,7 +5427,7 @@ int main(int argc, char *argv[])
 	}
 
 	pthread_mutex_init(&fctx.bfl, NULL);
-	ret = fuse_main(args.argc, args.argv, &fs_ops, &fctx);
+	ret = fuse4fs_main(&args, &fctx);
 	pthread_mutex_destroy(&fctx.bfl);
 
 	switch(ret) {

[PATCH 06/21] libsupport: port the kernel list.h to libsupport

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

In the next patch, we're going to add the xfsprogs cache manager code to
e2fsprogs.  That code is going into libsupport so that it doesn't become
part of the libext2fs ABI, and it depends on a richer set of list_head
helpers than what is in kernel-list.h, so port the Linux 6.17 list.h to
libsupport and drop the one in libext2fs.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/jfs_compat.h  |    2 
 lib/ext2fs/kernel-list.h |  111 ------
 lib/support/list.h       |  894 ++++++++++++++++++++++++++++++++++++++++++++++
 debugfs/Makefile.in      |   12 -
 e2fsck/Makefile.in       |   56 +--
 fuse4fs/Makefile.in      |    6 
 lib/e2p/Makefile.in      |    4 
 lib/ext2fs/Makefile.in   |   14 -
 misc/Makefile.in         |   12 -
 misc/tune2fs.c           |    4 
 10 files changed, 947 insertions(+), 168 deletions(-)
 delete mode 100644 lib/ext2fs/kernel-list.h
 create mode 100644 lib/support/list.h


diff --git a/lib/ext2fs/jfs_compat.h b/lib/ext2fs/jfs_compat.h
index 30b05822b6fd4d..8e598bcfa73ef7 100644
--- a/lib/ext2fs/jfs_compat.h
+++ b/lib/ext2fs/jfs_compat.h
@@ -2,7 +2,7 @@
 #ifndef _JFS_COMPAT_H
 #define _JFS_COMPAT_H
 
-#include "kernel-list.h"
+#include "support/list.h"
 #include <errno.h>
 #ifdef HAVE_NETINET_IN_H
 #include <netinet/in.h>
diff --git a/lib/ext2fs/kernel-list.h b/lib/ext2fs/kernel-list.h
deleted file mode 100644
index dd7b8e07dd56c4..00000000000000
--- a/lib/ext2fs/kernel-list.h
+++ /dev/null
@@ -1,111 +0,0 @@
-#ifndef _LINUX_LIST_H
-#define _LINUX_LIST_H
-
-#include "compiler.h"
-
-/*
- * Simple doubly linked list implementation.
- *
- * Some of the internal functions ("__xxx") are useful when
- * manipulating whole lists rather than single entries, as
- * sometimes we already know the next/prev entries and we can
- * generate better code by using them directly rather than
- * using the generic single-entry routines.
- */
-
-struct list_head {
-	struct list_head *next, *prev;
-};
-
-#define LIST_HEAD_INIT(name) { &(name), &(name) }
-
-#define INIT_LIST_HEAD(ptr) do { \
-	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
-} while (0)
-
-#if (!defined(__GNUC__) && !defined(__WATCOMC__))
-#define __inline__
-#endif
-
-/*
- * Insert a new entry between two known consecutive entries.
- *
- * This is only for internal list manipulation where we know
- * the prev/next entries already!
- */
-static __inline__ void __list_add(struct list_head * new,
-	struct list_head * prev,
-	struct list_head * next)
-{
-	next->prev = new;
-	new->next = next;
-	new->prev = prev;
-	prev->next = new;
-}
-
-/*
- * Insert a new entry after the specified head..
- */
-static __inline__ void list_add(struct list_head *new, struct list_head *head)
-{
-	__list_add(new, head, head->next);
-}
-
-/*
- * Insert a new entry at the tail
- */
-static __inline__ void list_add_tail(struct list_head *new, struct list_head *head)
-{
-	__list_add(new, head->prev, head);
-}
-
-/*
- * Delete a list entry by making the prev/next entries
- * point to each other.
- *
- * This is only for internal list manipulation where we know
- * the prev/next entries already!
- */
-static __inline__ void __list_del(struct list_head * prev,
-				  struct list_head * next)
-{
-	next->prev = prev;
-	prev->next = next;
-}
-
-static __inline__ void list_del(struct list_head *entry)
-{
-	__list_del(entry->prev, entry->next);
-}
-
-static __inline__ int list_empty(struct list_head *head)
-{
-	return head->next == head;
-}
-
-/*
- * Splice in "list" into "head"
- */
-static __inline__ void list_splice(struct list_head *list, struct list_head *head)
-{
-	struct list_head *first = list->next;
-
-	if (first != list) {
-		struct list_head *last = list->prev;
-		struct list_head *at = head->next;
-
-		first->prev = head;
-		head->next = first;
-
-		last->next = at;
-		at->prev = last;
-	}
-}
-
-#define list_entry(ptr, type, member) \
-	container_of(ptr, type, member)
-
-#define list_for_each(pos, head) \
-        for (pos = (head)->next; pos != (head); pos = pos->next)
-
-#endif
diff --git a/lib/support/list.h b/lib/support/list.h
new file mode 100644
index 00000000000000..df6c99708e4a8e
--- /dev/null
+++ b/lib/support/list.h
@@ -0,0 +1,894 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_LIST_H
+#define _LINUX_LIST_H
+
+#include <stdbool.h>
+
+struct list_head {
+	struct list_head *next, *prev;
+};
+
+#ifdef __GNUC__
+#define container_of(ptr, type, member) ({				\
+	__typeof__( ((type *)0)->member ) *__mptr = (ptr);	\
+	(type *)( (char *)__mptr - offsetof(type,member) );})
+#else
+#define container_of(ptr, type, member)				\
+	((type *)((char *)(ptr) - offsetof(type, member)))
+#endif
+
+/*
+ * Circular doubly linked list implementation.
+ *
+ * Some of the internal functions ("__xxx") are useful when
+ * manipulating whole lists rather than single entries, as
+ * sometimes we already know the next/prev entries and we can
+ * generate better code by using them directly rather than
+ * using the generic single-entry routines.
+ */
+
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+
+#define LIST_HEAD(name) \
+	struct list_head name = LIST_HEAD_INIT(name)
+
+/**
+ * INIT_LIST_HEAD - Initialize a list_head structure
+ * @list: list_head structure to be initialized.
+ *
+ * Initializes the list_head to point to itself.  If it is a list header,
+ * the result is an empty list.
+ */
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+	list->next = list;
+	list->prev = list;
+}
+
+#ifdef CONFIG_LIST_HARDENED
+
+#ifdef CONFIG_DEBUG_LIST
+# define __list_valid_slowpath
+#else
+# define __list_valid_slowpath __cold __preserve_most
+#endif
+
+/*
+ * Performs the full set of list corruption checks before __list_add().
+ * On list corruption reports a warning, and returns false.
+ */
+bool __list_valid_slowpath __list_add_valid_or_report(struct list_head *new,
+						      struct list_head *prev,
+						      struct list_head *next);
+
+/*
+ * Performs list corruption checks before __list_add(). Returns false if a
+ * corruption is detected, true otherwise.
+ *
+ * With CONFIG_LIST_HARDENED only, performs minimal list integrity checking
+ * inline to catch non-faulting corruptions, and only if a corruption is
+ * detected calls the reporting function __list_add_valid_or_report().
+ */
+static __always_inline bool __list_add_valid(struct list_head *new,
+					     struct list_head *prev,
+					     struct list_head *next)
+{
+	bool ret = true;
+
+	if (!IS_ENABLED(CONFIG_DEBUG_LIST)) {
+		/*
+		 * With the hardening version, elide checking if next and prev
+		 * are NULL, since the immediate dereference of them below would
+		 * result in a fault if NULL.
+		 *
+		 * With the reduced set of checks, we can afford to inline the
+		 * checks, which also gives the compiler a chance to elide some
+		 * of them completely if they can be proven at compile-time. If
+		 * one of the pre-conditions does not hold, the slow-path will
+		 * show a report which pre-condition failed.
+		 */
+		if (likely(next->prev == prev && prev->next == next && new != prev && new != next))
+			return true;
+		ret = false;
+	}
+
+	ret &= __list_add_valid_or_report(new, prev, next);
+	return ret;
+}
+
+/*
+ * Performs the full set of list corruption checks before __list_del_entry().
+ * On list corruption reports a warning, and returns false.
+ */
+bool __list_valid_slowpath __list_del_entry_valid_or_report(struct list_head *entry);
+
+/*
+ * Performs list corruption checks before __list_del_entry(). Returns false if a
+ * corruption is detected, true otherwise.
+ *
+ * With CONFIG_LIST_HARDENED only, performs minimal list integrity checking
+ * inline to catch non-faulting corruptions, and only if a corruption is
+ * detected calls the reporting function __list_del_entry_valid_or_report().
+ */
+static __always_inline bool __list_del_entry_valid(struct list_head *entry)
+{
+	bool ret = true;
+
+	if (!IS_ENABLED(CONFIG_DEBUG_LIST)) {
+		struct list_head *prev = entry->prev;
+		struct list_head *next = entry->next;
+
+		/*
+		 * With the hardening version, elide checking if next and prev
+		 * are NULL, LIST_POISON1 or LIST_POISON2, since the immediate
+		 * dereference of them below would result in a fault.
+		 */
+		if (likely(prev->next == entry && next->prev == entry))
+			return true;
+		ret = false;
+	}
+
+	ret &= __list_del_entry_valid_or_report(entry);
+	return ret;
+}
+#else
+static inline bool __list_add_valid(struct list_head *new,
+				struct list_head *prev,
+				struct list_head *next)
+{
+	return true;
+}
+static inline bool __list_del_entry_valid(struct list_head *entry)
+{
+	return true;
+}
+#endif
+
+/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_add(struct list_head *new,
+			      struct list_head *prev,
+			      struct list_head *next)
+{
+	if (!__list_add_valid(new, prev, next))
+		return;
+
+	next->prev = new;
+	new->next = next;
+	new->prev = prev;
+	prev->next = new;
+}
+
+/**
+ * list_add - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+	__list_add(new, head, head->next);
+}
+
+
+/**
+ * list_add_tail - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it before
+ *
+ * Insert a new entry before the specified head.
+ * This is useful for implementing queues.
+ */
+static inline void list_add_tail(struct list_head *new, struct list_head *head)
+{
+	__list_add(new, head->prev, head);
+}
+
+/*
+ * Delete a list entry by making the prev/next entries
+ * point to each other.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_del(struct list_head * prev, struct list_head * next)
+{
+	next->prev = prev;
+	prev->next = next;
+}
+
+/*
+ * Delete a list entry and clear the 'prev' pointer.
+ *
+ * This is a special-purpose list clearing method used in the networking code
+ * for lists allocated as per-cpu, where we don't want to incur the extra
+ * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this
+ * needs to check the node 'prev' pointer instead of calling list_empty().
+ */
+static inline void __list_del_clearprev(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+	entry->prev = NULL;
+}
+
+static inline void __list_del_entry(struct list_head *entry)
+{
+	if (!__list_del_entry_valid(entry))
+		return;
+
+	__list_del(entry->prev, entry->next);
+}
+
+/**
+ * list_del - deletes entry from list.
+ * @entry: the element to delete from the list.
+ * Note: list_empty() on entry does not return true after this, the entry is
+ * in an undefined state.
+ */
+static inline void list_del(struct list_head *entry)
+{
+	__list_del_entry(entry);
+	entry->next = NULL;
+	entry->prev = NULL;
+}
+
+/**
+ * list_replace - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * If @old was empty, it will be overwritten.
+ */
+static inline void list_replace(struct list_head *old,
+				struct list_head *new)
+{
+	new->next = old->next;
+	new->next->prev = new;
+	new->prev = old->prev;
+	new->prev->next = new;
+}
+
+/**
+ * list_replace_init - replace old entry by new one and initialize the old one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * If @old was empty, it will be overwritten.
+ */
+static inline void list_replace_init(struct list_head *old,
+				     struct list_head *new)
+{
+	list_replace(old, new);
+	INIT_LIST_HEAD(old);
+}
+
+/**
+ * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position
+ * @entry1: the location to place entry2
+ * @entry2: the location to place entry1
+ */
+static inline void list_swap(struct list_head *entry1,
+			     struct list_head *entry2)
+{
+	struct list_head *pos = entry2->prev;
+
+	list_del(entry2);
+	list_replace(entry1, entry2);
+	if (pos == entry1)
+		pos = entry2;
+	list_add(entry1, pos);
+}
+
+/**
+ * list_del_init - deletes entry from list and reinitialize it.
+ * @entry: the element to delete from the list.
+ */
+static inline void list_del_init(struct list_head *entry)
+{
+	__list_del_entry(entry);
+	INIT_LIST_HEAD(entry);
+}
+
+/**
+ * list_move - delete from one list and add as another's head
+ * @list: the entry to move
+ * @head: the head that will precede our entry
+ */
+static inline void list_move(struct list_head *list, struct list_head *head)
+{
+	__list_del_entry(list);
+	list_add(list, head);
+}
+
+/**
+ * list_move_tail - delete from one list and add as another's tail
+ * @list: the entry to move
+ * @head: the head that will follow our entry
+ */
+static inline void list_move_tail(struct list_head *list,
+				  struct list_head *head)
+{
+	__list_del_entry(list);
+	list_add_tail(list, head);
+}
+
+/**
+ * list_bulk_move_tail - move a subsection of a list to its tail
+ * @head: the head that will follow our entry
+ * @first: first entry to move
+ * @last: last entry to move, can be the same as first
+ *
+ * Move all entries between @first and including @last before @head.
+ * All three entries must belong to the same linked list.
+ */
+static inline void list_bulk_move_tail(struct list_head *head,
+				       struct list_head *first,
+				       struct list_head *last)
+{
+	first->prev->next = last->next;
+	last->next->prev = first->prev;
+
+	head->prev->next = first;
+	first->prev = head->prev;
+
+	last->next = head;
+	head->prev = last;
+}
+
+/**
+ * list_is_first -- tests whether @list is the first entry in list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_first(const struct list_head *list, const struct list_head *head)
+{
+	return list->prev == head;
+}
+
+/**
+ * list_is_last - tests whether @list is the last entry in list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_last(const struct list_head *list, const struct list_head *head)
+{
+	return list->next == head;
+}
+
+/**
+ * list_is_head - tests whether @list is the list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_head(const struct list_head *list, const struct list_head *head)
+{
+	return list == head;
+}
+
+/**
+ * list_empty - tests whether a list is empty
+ * @head: the list to test.
+ */
+static inline int list_empty(const struct list_head *head)
+{
+	return head->next == head;
+}
+
+/**
+ * list_rotate_left - rotate the list to the left
+ * @head: the head of the list
+ */
+static inline void list_rotate_left(struct list_head *head)
+{
+	struct list_head *first;
+
+	if (!list_empty(head)) {
+		first = head->next;
+		list_move_tail(first, head);
+	}
+}
+
+/**
+ * list_rotate_to_front() - Rotate list to specific item.
+ * @list: The desired new front of the list.
+ * @head: The head of the list.
+ *
+ * Rotates list so that @list becomes the new front of the list.
+ */
+static inline void list_rotate_to_front(struct list_head *list,
+					struct list_head *head)
+{
+	/*
+	 * Deletes the list head from the list denoted by @head and
+	 * places it as the tail of @list, this effectively rotates the
+	 * list so that @list is at the front.
+	 */
+	list_move_tail(head, list);
+}
+
+/**
+ * list_is_singular - tests whether a list has just one entry.
+ * @head: the list to test.
+ */
+static inline int list_is_singular(const struct list_head *head)
+{
+	return !list_empty(head) && (head->next == head->prev);
+}
+
+static inline void __list_cut_position(struct list_head *list,
+		struct list_head *head, struct list_head *entry)
+{
+	struct list_head *new_first = entry->next;
+	list->next = head->next;
+	list->next->prev = list;
+	list->prev = entry;
+	entry->next = list;
+	head->next = new_first;
+	new_first->prev = head;
+}
+
+/**
+ * list_cut_position - cut a list into two
+ * @list: a new list to add all removed entries
+ * @head: a list with entries
+ * @entry: an entry within head, could be the head itself
+ *	and if so we won't cut the list
+ *
+ * This helper moves the initial part of @head, up to and
+ * including @entry, from @head to @list. You should
+ * pass on @entry an element you know is on @head. @list
+ * should be an empty list or a list you do not care about
+ * losing its data.
+ *
+ */
+static inline void list_cut_position(struct list_head *list,
+		struct list_head *head, struct list_head *entry)
+{
+	if (list_empty(head))
+		return;
+	if (list_is_singular(head) && !list_is_head(entry, head) && (entry != head->next))
+		return;
+	if (list_is_head(entry, head))
+		INIT_LIST_HEAD(list);
+	else
+		__list_cut_position(list, head, entry);
+}
+
+/**
+ * list_cut_before - cut a list into two, before given entry
+ * @list: a new list to add all removed entries
+ * @head: a list with entries
+ * @entry: an entry within head, could be the head itself
+ *
+ * This helper moves the initial part of @head, up to but
+ * excluding @entry, from @head to @list.  You should pass
+ * in @entry an element you know is on @head.  @list should
+ * be an empty list or a list you do not care about losing
+ * its data.
+ * If @entry == @head, all entries on @head are moved to
+ * @list.
+ */
+static inline void list_cut_before(struct list_head *list,
+				   struct list_head *head,
+				   struct list_head *entry)
+{
+	if (head->next == entry) {
+		INIT_LIST_HEAD(list);
+		return;
+	}
+	list->next = head->next;
+	list->next->prev = list;
+	list->prev = entry->prev;
+	list->prev->next = list;
+	head->next = entry;
+	entry->prev = head;
+}
+
+static inline void __list_splice(const struct list_head *list,
+				 struct list_head *prev,
+				 struct list_head *next)
+{
+	struct list_head *first = list->next;
+	struct list_head *last = list->prev;
+
+	first->prev = prev;
+	prev->next = first;
+
+	last->next = next;
+	next->prev = last;
+}
+
+/**
+ * list_splice - join two lists, this is designed for stacks
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice(const struct list_head *list,
+				struct list_head *head)
+{
+	if (!list_empty(list))
+		__list_splice(list, head, head->next);
+}
+
+/**
+ * list_splice_tail - join two lists, each list being a queue
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice_tail(struct list_head *list,
+				struct list_head *head)
+{
+	if (!list_empty(list))
+		__list_splice(list, head->prev, head);
+}
+
+/**
+ * list_splice_init - join two lists and reinitialise the emptied list.
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_init(struct list_head *list,
+				    struct list_head *head)
+{
+	if (!list_empty(list)) {
+		__list_splice(list, head, head->next);
+		INIT_LIST_HEAD(list);
+	}
+}
+
+/**
+ * list_splice_tail_init - join two lists and reinitialise the emptied list
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * Each of the lists is a queue.
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_tail_init(struct list_head *list,
+					 struct list_head *head)
+{
+	if (!list_empty(list)) {
+		__list_splice(list, head->prev, head);
+		INIT_LIST_HEAD(list);
+	}
+}
+
+/**
+ * list_entry - get the struct for this entry
+ * @ptr:	the &struct list_head pointer.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_head within the struct.
+ */
+#define list_entry(ptr, type, member) \
+	container_of(ptr, type, member)
+
+/**
+ * list_first_entry - get the first element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_first_entry(ptr, type, member) \
+	list_entry((ptr)->next, type, member)
+
+/**
+ * list_last_entry - get the last element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_last_entry(ptr, type, member) \
+	list_entry((ptr)->prev, type, member)
+
+/**
+ * list_first_entry_or_null - get the first element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ */
+#define list_first_entry_or_null(ptr, type, member) ({ \
+	struct list_head *head__ = (ptr); \
+	struct list_head *pos__ = head__->next; \
+	pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
+})
+
+/**
+ * list_next_entry - get the next element in list
+ * @pos:	the type * to cursor
+ * @member:	the name of the list_head within the struct.
+ */
+#define list_next_entry(pos, member) \
+	list_entry((pos)->member.next, typeof(*(pos)), member)
+
+/**
+ * list_next_entry_circular - get the next element in list
+ * @pos:	the type * to cursor.
+ * @head:	the list head to take the element from.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Wraparound if pos is the last element (return the first element).
+ * Note, that list is expected to be not empty.
+ */
+#define list_next_entry_circular(pos, head, member) \
+	(list_is_last(&(pos)->member, head) ? \
+	list_first_entry(head, typeof(*(pos)), member) : list_next_entry(pos, member))
+
+/**
+ * list_prev_entry - get the prev element in list
+ * @pos:	the type * to cursor
+ * @member:	the name of the list_head within the struct.
+ */
+#define list_prev_entry(pos, member) \
+	list_entry((pos)->member.prev, typeof(*(pos)), member)
+
+/**
+ * list_prev_entry_circular - get the prev element in list
+ * @pos:	the type * to cursor.
+ * @head:	the list head to take the element from.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Wraparound if pos is the first element (return the last element).
+ * Note, that list is expected to be not empty.
+ */
+#define list_prev_entry_circular(pos, head, member) \
+	(list_is_first(&(pos)->member, head) ? \
+	list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(pos, member))
+
+/**
+ * list_for_each	-	iterate over a list
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each(pos, head) \
+	for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
+
+/**
+ * list_for_each_rcu - Iterate over a list in an RCU-safe fashion
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each_rcu(pos, head)		  \
+	for (pos = rcu_dereference((head)->next); \
+	     !list_is_head(pos, (head)); \
+	     pos = rcu_dereference(pos->next))
+
+/**
+ * list_for_each_continue - continue iteration over a list
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ *
+ * Continue to iterate over a list, continuing after the current position.
+ */
+#define list_for_each_continue(pos, head) \
+	for (pos = pos->next; !list_is_head(pos, (head)); pos = pos->next)
+
+/**
+ * list_for_each_prev	-	iterate over a list backwards
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each_prev(pos, head) \
+	for (pos = (head)->prev; !list_is_head(pos, (head)); pos = pos->prev)
+
+/**
+ * list_for_each_safe - iterate over a list safe against removal of list entry
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @n:		another &struct list_head to use as temporary storage
+ * @head:	the head for your list.
+ */
+#define list_for_each_safe(pos, n, head) \
+	for (pos = (head)->next, n = pos->next; \
+	     !list_is_head(pos, (head)); \
+	     pos = n, n = pos->next)
+
+/**
+ * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @n:		another &struct list_head to use as temporary storage
+ * @head:	the head for your list.
+ */
+#define list_for_each_prev_safe(pos, n, head) \
+	for (pos = (head)->prev, n = pos->prev; \
+	     !list_is_head(pos, (head)); \
+	     pos = n, n = pos->prev)
+
+/**
+ * list_count_nodes - count nodes in the list
+ * @head:	the head for your list.
+ */
+static inline size_t list_count_nodes(struct list_head *head)
+{
+	struct list_head *pos;
+	size_t count = 0;
+
+	list_for_each(pos, head)
+		count++;
+
+	return count;
+}
+
+/**
+ * list_entry_is_head - test if the entry points to the head of the list
+ * @pos:	the type * to cursor
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ */
+#define list_entry_is_head(pos, head, member)				\
+	list_is_head(&pos->member, (head))
+
+/**
+ * list_for_each_entry	-	iterate over list of given type
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ */
+#define list_for_each_entry(pos, head, member)				\
+	for (pos = list_first_entry(head, typeof(*pos), member);	\
+	     !list_entry_is_head(pos, head, member);			\
+	     pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_reverse - iterate backwards over list of given type.
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ */
+#define list_for_each_entry_reverse(pos, head, member)			\
+	for (pos = list_last_entry(head, typeof(*pos), member);		\
+	     !list_entry_is_head(pos, head, member); 			\
+	     pos = list_prev_entry(pos, member))
+
+/**
+ * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
+ * @pos:	the type * to use as a start point
+ * @head:	the head of the list
+ * @member:	the name of the list_head within the struct.
+ *
+ * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
+ */
+#define list_prepare_entry(pos, head, member) \
+	((pos) ? : list_entry(head, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_continue - continue iteration over list of given type
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Continue to iterate over list of given type, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue(pos, head, member) 		\
+	for (pos = list_next_entry(pos, member);			\
+	     !list_entry_is_head(pos, head, member);			\
+	     pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_continue_reverse - iterate backwards from the given point
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Start to iterate over list of given type backwards, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue_reverse(pos, head, member)		\
+	for (pos = list_prev_entry(pos, member);			\
+	     !list_entry_is_head(pos, head, member);			\
+	     pos = list_prev_entry(pos, member))
+
+/**
+ * list_for_each_entry_from - iterate over list of given type from the current point
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Iterate over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from(pos, head, member) 			\
+	for (; !list_entry_is_head(pos, head, member);			\
+	     pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_from_reverse - iterate backwards over list of given type
+ *                                    from the current point
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Iterate backwards over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from_reverse(pos, head, member)		\
+	for (; !list_entry_is_head(pos, head, member);			\
+	     pos = list_prev_entry(pos, member))
+
+/**
+ * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ */
+#define list_for_each_entry_safe(pos, n, head, member)			\
+	for (pos = list_first_entry(head, typeof(*pos), member),	\
+		n = list_next_entry(pos, member);			\
+	     !list_entry_is_head(pos, head, member); 			\
+	     pos = n, n = list_next_entry(n, member))
+
+/**
+ * list_for_each_entry_safe_continue - continue list iteration safe against removal
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Iterate over list of given type, continuing after current point,
+ * safe against removal of list entry.
+ */
+#define list_for_each_entry_safe_continue(pos, n, head, member) 		\
+	for (pos = list_next_entry(pos, member), 				\
+		n = list_next_entry(pos, member);				\
+	     !list_entry_is_head(pos, head, member);				\
+	     pos = n, n = list_next_entry(n, member))
+
+/**
+ * list_for_each_entry_safe_from - iterate over list from current point safe against removal
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Iterate over list of given type from current point, safe against
+ * removal of list entry.
+ */
+#define list_for_each_entry_safe_from(pos, n, head, member) 			\
+	for (n = list_next_entry(pos, member);					\
+	     !list_entry_is_head(pos, head, member);				\
+	     pos = n, n = list_next_entry(n, member))
+
+/**
+ * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Iterate backwards over list of given type, safe against removal
+ * of list entry.
+ */
+#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
+	for (pos = list_last_entry(head, typeof(*pos), member),		\
+		n = list_prev_entry(pos, member);			\
+	     !list_entry_is_head(pos, head, member); 			\
+	     pos = n, n = list_prev_entry(n, member))
+
+/**
+ * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
+ * @pos:	the loop cursor used in the list_for_each_entry_safe loop
+ * @n:		temporary storage used in list_for_each_entry_safe
+ * @member:	the name of the list_head within the struct.
+ *
+ * list_safe_reset_next is not safe to use in general if the list may be
+ * modified concurrently (eg. the lock is dropped in the loop body). An
+ * exception to this is if the cursor element (pos) is pinned in the list,
+ * and list_safe_reset_next is called after re-taking the lock and before
+ * completing the current iteration of the loop body.
+ */
+#define list_safe_reset_next(pos, n, member)				\
+	n = list_next_entry(pos, member)
+
+#endif
diff --git a/debugfs/Makefile.in b/debugfs/Makefile.in
index 689bf0c4a3c13d..700ae87418c268 100644
--- a/debugfs/Makefile.in
+++ b/debugfs/Makefile.in
@@ -195,7 +195,7 @@ debugfs.o: $(srcdir)/debugfs.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h $(top_srcdir)/version.h \
  $(srcdir)/../e2fsck/jfs_user.h $(top_srcdir)/lib/ext2fs/kernel-jbd.h \
- $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/ext2fs/kernel-list.h \
+ $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/support/list.h \
  $(top_srcdir)/lib/ext2fs/compiler.h $(top_srcdir)/lib/support/plausible.h
 util.o: $(srcdir)/util.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/ss/ss.h \
@@ -287,7 +287,7 @@ logdump.o: $(srcdir)/logdump.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h $(srcdir)/../e2fsck/jfs_user.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h
 htree.o: $(srcdir)/htree.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/debugfs.h $(top_srcdir)/lib/ss/ss.h \
@@ -408,7 +408,7 @@ journal.o: $(srcdir)/journal.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/ext2fs/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/kernel-jbd.h \
- $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/ext2fs/kernel-list.h \
+ $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/support/list.h \
  $(top_srcdir)/lib/ext2fs/compiler.h
 revoke.o: $(srcdir)/../e2fsck/revoke.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -418,7 +418,7 @@ revoke.o: $(srcdir)/../e2fsck/revoke.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_builddir)/lib/ext2fs/ext2_err.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/kernel-jbd.h \
- $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/ext2fs/kernel-list.h \
+ $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/support/list.h \
  $(top_srcdir)/lib/ext2fs/compiler.h
 recovery.o: $(srcdir)/../e2fsck/recovery.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -428,7 +428,7 @@ recovery.o: $(srcdir)/../e2fsck/recovery.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_builddir)/lib/ext2fs/ext2_err.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/kernel-jbd.h \
- $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/ext2fs/kernel-list.h \
+ $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/support/list.h \
  $(top_srcdir)/lib/ext2fs/compiler.h
 do_journal.o: $(srcdir)/do_journal.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/debugfs.h $(top_srcdir)/lib/ss/ss.h \
@@ -442,7 +442,7 @@ do_journal.o: $(srcdir)/do_journal.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/journal.h $(srcdir)/../e2fsck/jfs_user.h
 do_orphan.o: $(srcdir)/do_orphan.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/debugfs.h $(top_srcdir)/lib/ss/ss.h \
diff --git a/e2fsck/Makefile.in b/e2fsck/Makefile.in
index fbb7b156d5c759..52fad9cbfd2b23 100644
--- a/e2fsck/Makefile.in
+++ b/e2fsck/Makefile.in
@@ -282,7 +282,7 @@ e2fsck.o: $(srcdir)/e2fsck.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h
 super.o: $(srcdir)/super.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -296,7 +296,7 @@ super.o: $(srcdir)/super.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h
 pass1.o: $(srcdir)/pass1.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -310,7 +310,7 @@ pass1.o: $(srcdir)/pass1.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/e2p/e2p.h $(srcdir)/problem.h
 pass1b.o: $(srcdir)/pass1b.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/et/com_err.h \
@@ -324,7 +324,7 @@ pass1b.o: $(srcdir)/pass1b.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h $(top_srcdir)/lib/support/dict.h
 pass2.o: $(srcdir)/pass2.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -338,7 +338,7 @@ pass2.o: $(srcdir)/pass2.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h $(top_srcdir)/lib/support/dict.h
 pass3.o: $(srcdir)/pass3.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -352,7 +352,7 @@ pass3.o: $(srcdir)/pass3.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h
 pass4.o: $(srcdir)/pass4.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -366,7 +366,7 @@ pass4.o: $(srcdir)/pass4.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h
 pass5.o: $(srcdir)/pass5.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -380,7 +380,7 @@ pass5.o: $(srcdir)/pass5.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h
 journal.o: $(srcdir)/journal.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/jfs_user.h $(srcdir)/e2fsck.h \
@@ -394,7 +394,7 @@ journal.o: $(srcdir)/journal.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h $(srcdir)/problem.h
 recovery.o: $(srcdir)/recovery.c $(srcdir)/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -408,7 +408,7 @@ recovery.o: $(srcdir)/recovery.c $(srcdir)/jfs_user.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h
 revoke.o: $(srcdir)/revoke.c $(srcdir)/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -422,7 +422,7 @@ revoke.o: $(srcdir)/revoke.c $(srcdir)/jfs_user.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h
 badblocks.o: $(srcdir)/badblocks.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/et/com_err.h \
@@ -436,7 +436,7 @@ badblocks.o: $(srcdir)/badblocks.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 util.o: $(srcdir)/util.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -449,7 +449,7 @@ util.o: $(srcdir)/util.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 unix.o: $(srcdir)/unix.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/e2p/e2p.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -463,7 +463,7 @@ unix.o: $(srcdir)/unix.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h $(srcdir)/jfs_user.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h $(top_srcdir)/version.h
 dirinfo.o: $(srcdir)/dirinfo.c $(top_builddir)/lib/config.h \
@@ -478,7 +478,7 @@ dirinfo.o: $(srcdir)/dirinfo.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/tdb.h
 dx_dirinfo.o: $(srcdir)/dx_dirinfo.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -492,7 +492,7 @@ dx_dirinfo.o: $(srcdir)/dx_dirinfo.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 ehandler.o: $(srcdir)/ehandler.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -505,7 +505,7 @@ ehandler.o: $(srcdir)/ehandler.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 problem.o: $(srcdir)/problem.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -518,7 +518,7 @@ problem.o: $(srcdir)/problem.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h $(srcdir)/problemP.h
 message.o: $(srcdir)/message.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/support/quotaio.h \
@@ -531,7 +531,7 @@ message.o: $(srcdir)/message.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/quotaio_tree.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/support/profile.h $(top_builddir)/lib/support/prof_err.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h
 ea_refcount.o: $(srcdir)/ea_refcount.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -545,7 +545,7 @@ ea_refcount.o: $(srcdir)/ea_refcount.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 rehash.o: $(srcdir)/rehash.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -558,7 +558,7 @@ rehash.o: $(srcdir)/rehash.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h $(top_srcdir)/lib/support/sort_r.h
 readahead.o: $(srcdir)/readahead.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -572,7 +572,7 @@ readahead.o: $(srcdir)/readahead.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 region.o: $(srcdir)/region.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -585,7 +585,7 @@ region.o: $(srcdir)/region.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 sigcatcher.o: $(srcdir)/sigcatcher.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -598,7 +598,7 @@ sigcatcher.o: $(srcdir)/sigcatcher.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 logfile.o: $(srcdir)/logfile.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -611,7 +611,7 @@ logfile.o: $(srcdir)/logfile.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 quota.o: $(srcdir)/quota.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
@@ -624,7 +624,7 @@ quota.o: $(srcdir)/quota.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h
 extents.o: $(srcdir)/extents.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -638,7 +638,7 @@ extents.o: $(srcdir)/extents.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h
 encrypted_files.o: $(srcdir)/encrypted_files.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2fsck.h \
@@ -652,5 +652,5 @@ encrypted_files.o: $(srcdir)/encrypted_files.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(srcdir)/problem.h $(top_srcdir)/lib/ext2fs/rbtree.h
diff --git a/fuse4fs/Makefile.in b/fuse4fs/Makefile.in
index bc137a765ee2b7..6b41d1dd5ffe8d 100644
--- a/fuse4fs/Makefile.in
+++ b/fuse4fs/Makefile.in
@@ -160,7 +160,7 @@ journal.o: $(srcdir)/../debugfs/journal.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h
 revoke.o: $(srcdir)/../e2fsck/revoke.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -174,7 +174,7 @@ revoke.o: $(srcdir)/../e2fsck/revoke.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h
 recovery.o: $(srcdir)/../e2fsck/recovery.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -188,5 +188,5 @@ recovery.o: $(srcdir)/../e2fsck/recovery.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h
diff --git a/lib/e2p/Makefile.in b/lib/e2p/Makefile.in
index 92d9c018fe46c8..f642f5ec367c93 100644
--- a/lib/e2p/Makefile.in
+++ b/lib/e2p/Makefile.in
@@ -130,7 +130,7 @@ feature.o: $(srcdir)/feature.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/ext2fs/ext2_err.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/kernel-jbd.h \
- $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/ext2fs/kernel-list.h \
+ $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/support/list.h \
  $(top_srcdir)/lib/ext2fs/compiler.h
 fgetflags.o: $(srcdir)/fgetflags.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2p.h \
@@ -173,7 +173,7 @@ ljs.o: $(srcdir)/ljs.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(srcdir)/e2p.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h
 mntopts.o: $(srcdir)/mntopts.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/e2p.h \
  $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h
diff --git a/lib/ext2fs/Makefile.in b/lib/ext2fs/Makefile.in
index e9a6ced244ea26..1d0991defff804 100644
--- a/lib/ext2fs/Makefile.in
+++ b/lib/ext2fs/Makefile.in
@@ -1032,7 +1032,7 @@ mkjournal.o: $(srcdir)/mkjournal.c $(top_builddir)/lib/config.h \
  $(srcdir)/ext3_extents.h $(top_srcdir)/lib/et/com_err.h $(srcdir)/ext2_io.h \
  $(top_builddir)/lib/ext2fs/ext2_err.h $(srcdir)/ext2_ext_attr.h \
  $(srcdir)/hashmap.h $(srcdir)/bitops.h $(srcdir)/kernel-jbd.h \
- $(srcdir)/jfs_compat.h $(srcdir)/kernel-list.h $(srcdir)/compiler.h
+ $(srcdir)/jfs_compat.h $(srcdir)/../support/list.h $(srcdir)/compiler.h
 mmp.o: $(srcdir)/mmp.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/ext2_fs.h \
  $(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h \
@@ -1263,7 +1263,7 @@ debugfs.o: $(top_srcdir)/debugfs/debugfs.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/quotaio.h $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h $(top_srcdir)/debugfs/../version.h \
  $(srcdir)/../../e2fsck/jfs_user.h $(srcdir)/kernel-jbd.h \
- $(srcdir)/jfs_compat.h $(srcdir)/kernel-list.h $(srcdir)/compiler.h \
+ $(srcdir)/jfs_compat.h $(srcdir)/../support/list.h $(srcdir)/compiler.h \
  $(top_srcdir)/lib/support/plausible.h
 util.o: $(top_srcdir)/debugfs/util.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/ss/ss.h \
@@ -1353,7 +1353,7 @@ logdump.o: $(top_srcdir)/debugfs/logdump.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/debugfs/../misc/create_inode.h $(top_srcdir)/lib/e2p/e2p.h \
  $(top_srcdir)/lib/support/quotaio.h $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h $(srcdir)/../../e2fsck/jfs_user.h \
- $(srcdir)/kernel-jbd.h $(srcdir)/jfs_compat.h $(srcdir)/kernel-list.h \
+ $(srcdir)/kernel-jbd.h $(srcdir)/jfs_compat.h $(srcdir)/../support/list.h \
  $(srcdir)/compiler.h $(srcdir)/fast_commit.h
 htree.o: $(top_srcdir)/debugfs/htree.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/debugfs/debugfs.h \
@@ -1469,14 +1469,14 @@ journal.o: $(top_srcdir)/debugfs/journal.c $(top_builddir)/lib/config.h \
  $(srcdir)/ext3_extents.h $(top_srcdir)/lib/et/com_err.h $(srcdir)/ext2_io.h \
  $(top_builddir)/lib/ext2fs/ext2_err.h $(srcdir)/ext2_ext_attr.h \
  $(srcdir)/hashmap.h $(srcdir)/bitops.h $(srcdir)/kernel-jbd.h \
- $(srcdir)/jfs_compat.h $(srcdir)/kernel-list.h $(srcdir)/compiler.h
+ $(srcdir)/jfs_compat.h $(srcdir)/../support/list.h $(srcdir)/compiler.h
 revoke.o: $(top_srcdir)/e2fsck/revoke.c $(top_srcdir)/e2fsck/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
  $(srcdir)/ext2_fs.h $(top_builddir)/lib/ext2fs/ext2_types.h \
  $(srcdir)/ext2fs.h $(srcdir)/ext3_extents.h $(top_srcdir)/lib/et/com_err.h \
  $(srcdir)/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h \
  $(srcdir)/ext2_ext_attr.h $(srcdir)/hashmap.h $(srcdir)/bitops.h \
- $(srcdir)/kernel-jbd.h $(srcdir)/jfs_compat.h $(srcdir)/kernel-list.h \
+ $(srcdir)/kernel-jbd.h $(srcdir)/jfs_compat.h $(srcdir)/../support/list.h \
  $(srcdir)/compiler.h
 recovery.o: $(top_srcdir)/e2fsck/recovery.c $(top_srcdir)/e2fsck/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -1484,7 +1484,7 @@ recovery.o: $(top_srcdir)/e2fsck/recovery.c $(top_srcdir)/e2fsck/jfs_user.h \
  $(srcdir)/ext2fs.h $(srcdir)/ext3_extents.h $(top_srcdir)/lib/et/com_err.h \
  $(srcdir)/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h \
  $(srcdir)/ext2_ext_attr.h $(srcdir)/hashmap.h $(srcdir)/bitops.h \
- $(srcdir)/kernel-jbd.h $(srcdir)/jfs_compat.h $(srcdir)/kernel-list.h \
+ $(srcdir)/kernel-jbd.h $(srcdir)/jfs_compat.h $(srcdir)/../support/list.h \
  $(srcdir)/compiler.h
 do_journal.o: $(top_srcdir)/debugfs/do_journal.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/debugfs/debugfs.h \
@@ -1497,7 +1497,7 @@ do_journal.o: $(top_srcdir)/debugfs/do_journal.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/debugfs/../misc/create_inode.h $(top_srcdir)/lib/e2p/e2p.h \
  $(top_srcdir)/lib/support/quotaio.h $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h $(srcdir)/kernel-jbd.h \
- $(srcdir)/jfs_compat.h $(srcdir)/kernel-list.h $(srcdir)/compiler.h \
+ $(srcdir)/jfs_compat.h $(srcdir)/../support/list.h $(srcdir)/compiler.h \
  $(top_srcdir)/debugfs/journal.h $(srcdir)/../../e2fsck/jfs_user.h
 do_orphan.o: $(top_srcdir)/debugfs/do_orphan.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/debugfs/debugfs.h \
diff --git a/misc/Makefile.in b/misc/Makefile.in
index b63a0424b19fec..ec964688acd623 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -736,7 +736,7 @@ tune2fs.o: $(srcdir)/tune2fs.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/ext2fs/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/kernel-jbd.h \
- $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/ext2fs/kernel-list.h \
+ $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/support/list.h \
  $(top_srcdir)/lib/ext2fs/compiler.h $(top_srcdir)/lib/support/plausible.h \
  $(top_srcdir)/lib/support/quotaio.h $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h $(top_srcdir)/lib/support/devname.h \
@@ -789,7 +789,7 @@ dumpe2fs.o: $(srcdir)/dumpe2fs.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/e2p/e2p.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/support/devname.h $(top_srcdir)/lib/support/nls-enable.h \
  $(top_srcdir)/lib/support/plausible.h $(top_srcdir)/version.h
 badblocks.o: $(srcdir)/badblocks.c $(top_builddir)/lib/config.h \
@@ -812,7 +812,7 @@ util.o: $(srcdir)/util.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/ext2fs/ext2_err.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/kernel-jbd.h \
- $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/ext2fs/kernel-list.h \
+ $(top_srcdir)/lib/ext2fs/jfs_compat.h $(top_srcdir)/lib/support/list.h \
  $(top_srcdir)/lib/ext2fs/compiler.h $(top_srcdir)/lib/support/nls-enable.h \
  $(top_srcdir)/lib/support/devname.h $(srcdir)/util.h
 uuidgen.o: $(srcdir)/uuidgen.c $(top_builddir)/lib/config.h \
@@ -907,7 +907,7 @@ journal.o: $(srcdir)/../debugfs/journal.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h
 revoke.o: $(srcdir)/../e2fsck/revoke.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -921,7 +921,7 @@ revoke.o: $(srcdir)/../e2fsck/revoke.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h
 recovery.o: $(srcdir)/../e2fsck/recovery.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_builddir)/lib/config.h $(top_builddir)/lib/dirpaths.h \
@@ -935,5 +935,5 @@ recovery.o: $(srcdir)/../e2fsck/recovery.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_srcdir)/lib/support/dqblk_v2.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/fast_commit.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
- $(top_srcdir)/lib/ext2fs/kernel-list.h $(top_srcdir)/lib/ext2fs/compiler.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/ext2fs/compiler.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 3db57632c88d42..ac440176351e83 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -2857,10 +2857,6 @@ static int expand_inode_table(ext2_filsys fs, unsigned long new_ino_size)
 }
 
 
-#define list_for_each_safe(pos, pnext, head) \
-	for (pos = (head)->next, pnext = pos->next; pos != (head); \
-	     pos = pnext, pnext = pos->next)
-
 static void free_blk_move_list(void)
 {
 	struct list_head *entry, *tmp;

[PATCH 07/21] libsupport: add a cache

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Reuse the cache code from xfsprogs.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h     |  139 +++++++++
 lib/support/list.h      |    7 
 lib/support/xbitops.h   |  128 ++++++++
 lib/support/Makefile.in |    8 -
 lib/support/cache.c     |  739 +++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 1019 insertions(+), 2 deletions(-)
 create mode 100644 lib/support/cache.h
 create mode 100644 lib/support/xbitops.h
 create mode 100644 lib/support/cache.c


diff --git a/lib/support/cache.h b/lib/support/cache.h
new file mode 100644
index 00000000000000..16b17a9b7a1a51
--- /dev/null
+++ b/lib/support/cache.h
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2006 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#ifndef __CACHE_H__
+#define __CACHE_H__
+
+/*
+ * initialisation flags
+ */
+/*
+ * xfs_db always writes changes immediately, and so we need to purge buffers
+ * when we get a buffer lookup mismatch due to reading the same block with a
+ * different buffer configuration.
+ */
+#define CACHE_MISCOMPARE_PURGE	(1 << 0)
+
+/*
+ * cache object campare return values
+ */
+enum {
+	CACHE_HIT,
+	CACHE_MISS,
+	CACHE_PURGE,
+};
+
+#define	HASH_CACHE_RATIO	8
+
+/*
+ * Cache priorities range from BASE to MAX.
+ *
+ * For prefetch support, the top half of the range starts at
+ * CACHE_PREFETCH_PRIORITY and everytime the buffer is fetched and is at or
+ * above this priority level, it is reduced to below this level (refer to
+ * libxfs_buf_get).
+ *
+ * If we have dirty nodes, we can't recycle them until they've been cleaned. To
+ * keep these out of the reclaimable lists (as there can be lots of them) give
+ * them their own priority that the shaker doesn't attempt to walk.
+ */
+
+#define CACHE_BASE_PRIORITY	0
+#define CACHE_PREFETCH_PRIORITY	8
+#define CACHE_MAX_PRIORITY	15
+#define CACHE_DIRTY_PRIORITY	(CACHE_MAX_PRIORITY + 1)
+#define CACHE_NR_PRIORITIES	CACHE_DIRTY_PRIORITY
+
+/*
+ * Simple, generic implementation of a cache (arbitrary data).
+ * Provides a hash table with a capped number of cache entries.
+ */
+
+struct cache;
+struct cache_node;
+
+typedef void *cache_key_t;
+
+typedef void (*cache_walk_t)(struct cache_node *);
+typedef struct cache_node * (*cache_node_alloc_t)(cache_key_t);
+typedef int (*cache_node_flush_t)(struct cache_node *);
+typedef void (*cache_node_relse_t)(struct cache_node *);
+typedef unsigned int (*cache_node_hash_t)(cache_key_t, unsigned int,
+					  unsigned int);
+typedef int (*cache_node_compare_t)(struct cache_node *, cache_key_t);
+typedef unsigned int (*cache_bulk_relse_t)(struct cache *, struct list_head *);
+typedef int (*cache_node_get_t)(struct cache_node *);
+typedef void (*cache_node_put_t)(struct cache_node *);
+
+struct cache_operations {
+	cache_node_hash_t	hash;
+	cache_node_alloc_t	alloc;
+	cache_node_flush_t	flush;
+	cache_node_relse_t	relse;
+	cache_node_compare_t	compare;
+	cache_bulk_relse_t	bulkrelse;	/* optional */
+	cache_node_get_t	get;		/* optional */
+	cache_node_put_t	put;		/* optional */
+};
+
+struct cache_hash {
+	struct list_head	ch_list;	/* hash chain head */
+	unsigned int		ch_count;	/* hash chain length */
+	pthread_mutex_t		ch_mutex;	/* hash chain mutex */
+};
+
+struct cache_mru {
+	struct list_head	cm_list;	/* MRU head */
+	unsigned int		cm_count;	/* MRU length */
+	pthread_mutex_t		cm_mutex;	/* MRU lock */
+};
+
+struct cache_node {
+	struct list_head	cn_hash;	/* hash chain */
+	struct list_head	cn_mru;		/* MRU chain */
+	unsigned int		cn_count;	/* reference count */
+	unsigned int		cn_hashidx;	/* hash chain index */
+	int			cn_priority;	/* priority, -1 = free list */
+	int			cn_old_priority;/* saved pre-dirty prio */
+	pthread_mutex_t		cn_mutex;	/* node mutex */
+};
+
+struct cache {
+	int			c_flags;	/* behavioural flags */
+	unsigned int		c_maxcount;	/* max cache nodes */
+	unsigned int		c_count;	/* count of nodes */
+	pthread_mutex_t		c_mutex;	/* node count mutex */
+	cache_node_hash_t	hash;		/* node hash function */
+	cache_node_alloc_t	alloc;		/* allocation function */
+	cache_node_flush_t	flush;		/* flush dirty data function */
+	cache_node_relse_t	relse;		/* memory free function */
+	cache_node_compare_t	compare;	/* comparison routine */
+	cache_bulk_relse_t	bulkrelse;	/* bulk release routine */
+	cache_node_get_t	get;		/* prepare cache node after get */
+	cache_node_put_t	put;		/* prepare to put cache node */
+	unsigned int		c_hashsize;	/* hash bucket count */
+	unsigned int		c_hashshift;	/* hash key shift */
+	struct cache_hash	*c_hash;	/* hash table buckets */
+	struct cache_mru	c_mrus[CACHE_DIRTY_PRIORITY + 1];
+	unsigned long long	c_misses;	/* cache misses */
+	unsigned long long	c_hits;		/* cache hits */
+	unsigned int 		c_max;		/* max nodes ever used */
+};
+
+struct cache *cache_init(int, unsigned int, const struct cache_operations *);
+void cache_destroy(struct cache *);
+void cache_walk(struct cache *, cache_walk_t);
+void cache_purge(struct cache *);
+void cache_flush(struct cache *);
+
+int cache_node_get(struct cache *, cache_key_t, struct cache_node **);
+void cache_node_put(struct cache *, struct cache_node *);
+void cache_node_set_priority(struct cache *, struct cache_node *, int);
+int cache_node_get_priority(struct cache_node *);
+int cache_node_purge(struct cache *, cache_key_t, struct cache_node *);
+void cache_report(FILE *fp, const char *, struct cache *);
+int cache_overflowed(struct cache *);
+
+#endif	/* __CACHE_H__ */
diff --git a/lib/support/list.h b/lib/support/list.h
index df6c99708e4a8e..0e00e446dd7214 100644
--- a/lib/support/list.h
+++ b/lib/support/list.h
@@ -17,6 +17,13 @@ struct list_head {
 	((type *)((char *)(ptr) - offsetof(type, member)))
 #endif
 
+static inline void list_head_destroy(struct list_head *list)
+{
+	list->next = list->prev = NULL;
+}
+
+#define list_head_init(list) INIT_LIST_HEAD(list)
+
 /*
  * Circular doubly linked list implementation.
  *
diff --git a/lib/support/xbitops.h b/lib/support/xbitops.h
new file mode 100644
index 00000000000000..78a8f2a8545f4c
--- /dev/null
+++ b/lib/support/xbitops.h
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef __BITOPS_H__
+#define __BITOPS_H__
+
+/*
+ * fls: find last bit set.
+ */
+
+static inline int fls(int x)
+{
+	int r = 32;
+
+	if (!x)
+		return 0;
+	if (!(x & 0xffff0000u)) {
+		x = (x & 0xffffu) << 16;
+		r -= 16;
+	}
+	if (!(x & 0xff000000u)) {
+		x = (x & 0xffffffu) << 8;
+		r -= 8;
+	}
+	if (!(x & 0xf0000000u)) {
+		x = (x & 0xfffffffu) << 4;
+		r -= 4;
+	}
+	if (!(x & 0xc0000000u)) {
+		x = (x & 0x3fffffffu) << 2;
+		r -= 2;
+	}
+	if (!(x & 0x80000000u)) {
+		r -= 1;
+	}
+	return r;
+}
+
+static inline int fls64(uint64_t x)
+{
+	uint32_t h = x >> 32;
+	if (h)
+		return fls(h) + 32;
+	return fls(x);
+}
+
+static inline unsigned fls_long(unsigned long l)
+{
+        if (sizeof(l) == 4)
+                return fls(l);
+        return fls64(l);
+}
+
+/*
+ * ffz: find first zero bit.
+ * Result is undefined if no zero bit exists.
+ */
+#define ffz(x)	ffs(~(x))
+
+/*
+ * XFS bit manipulation routines.  Repeated here so that some programs
+ * don't have to link in all of libxfs just to have bit manipulation.
+ */
+
+/*
+ * masks with n high/low bits set, 64-bit values
+ */
+static inline uint64_t mask64hi(int n)
+{
+	return (uint64_t)-1 << (64 - (n));
+}
+static inline uint32_t mask32lo(int n)
+{
+	return ((uint32_t)1 << (n)) - 1;
+}
+static inline uint64_t mask64lo(int n)
+{
+	return ((uint64_t)1 << (n)) - 1;
+}
+
+/* Get high bit set out of 32-bit argument, -1 if none set */
+static inline int highbit32(uint32_t v)
+{
+	return fls(v) - 1;
+}
+
+/* Get high bit set out of 64-bit argument, -1 if none set */
+static inline int highbit64(uint64_t v)
+{
+	return fls64(v) - 1;
+}
+
+/* Get low bit set out of 32-bit argument, -1 if none set */
+static inline int lowbit32(uint32_t v)
+{
+	return ffs(v) - 1;
+}
+
+/* Get low bit set out of 64-bit argument, -1 if none set */
+static inline int lowbit64(uint64_t v)
+{
+	uint32_t	w = (uint32_t)v;
+	int		n = 0;
+
+	if (w) {	/* lower bits */
+		n = ffs(w);
+	} else {	/* upper bits */
+		w = (uint32_t)(v >> 32);
+		if (w) {
+			n = ffs(w);
+			if (n)
+				n += 32;
+		}
+	}
+	return n - 1;
+}
+
+/**
+ * __rounddown_pow_of_two() - round down to nearest power of two
+ * @n: value to round down
+ */
+static inline __attribute__((const))
+unsigned long __rounddown_pow_of_two(unsigned long n)
+{
+	return 1UL << (fls_long(n) - 1);
+}
+
+#define rounddown_pow_of_two(n) __rounddown_pow_of_two(n)
+
+#endif
diff --git a/lib/support/Makefile.in b/lib/support/Makefile.in
index 3f26cd30172f51..13d6f06f150afd 100644
--- a/lib/support/Makefile.in
+++ b/lib/support/Makefile.in
@@ -25,7 +25,8 @@ OBJS=		cstring.o \
 		quotaio_v2.o \
 		quotaio_tree.o \
 		dict.o \
-		devname.o
+		devname.o \
+		cache.o
 
 SRCS=		$(srcdir)/argv_parse.c \
 		$(srcdir)/cstring.c \
@@ -40,7 +41,8 @@ SRCS=		$(srcdir)/argv_parse.c \
 		$(srcdir)/quotaio_tree.c \
 		$(srcdir)/quotaio_v2.c \
 		$(srcdir)/dict.c \
-		$(srcdir)/devname.c
+		$(srcdir)/devname.c \
+		$(srcdir)/cache.c
 
 LIBRARY= libsupport
 LIBDIR= support
@@ -183,3 +185,5 @@ dict.o: $(srcdir)/dict.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/dict.h
 devname.o: $(srcdir)/devname.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/devname.h $(srcdir)/nls-enable.h
+cache.o: $(srcdir)/cache.c $(top_builddir)/lib/config.h \
+ $(srcdir)/cache.h $(srcdir)/list.h $(srcdir)/xbitops.h
diff --git a/lib/support/cache.c b/lib/support/cache.c
new file mode 100644
index 00000000000000..fe04f62f262aaa
--- /dev/null
+++ b/lib/support/cache.c
@@ -0,0 +1,739 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2006 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "list.h"
+#include "cache.h"
+#include "xbitops.h"
+
+#define CACHE_DEBUG 1
+#undef CACHE_DEBUG
+#define CACHE_DEBUG 1
+#undef CACHE_ABORT
+/* #define CACHE_ABORT 1 */
+
+#define CACHE_SHAKE_COUNT	64
+
+#ifdef CACHE_DEBUG
+# include <assert.h>
+# define ASSERT(x)		assert(x)
+#endif
+
+static unsigned int cache_generic_bulkrelse(struct cache *, struct list_head *);
+
+struct cache *
+cache_init(
+	int			flags,
+	unsigned int		hashsize,
+	const struct cache_operations	*cache_operations)
+{
+	struct cache *		cache;
+	unsigned int		i, maxcount;
+
+	maxcount = hashsize * HASH_CACHE_RATIO;
+
+	if (!(cache = malloc(sizeof(struct cache))))
+		return NULL;
+	if (!(cache->c_hash = calloc(hashsize, sizeof(struct cache_hash)))) {
+		free(cache);
+		return NULL;
+	}
+
+	cache->c_flags = flags;
+	cache->c_count = 0;
+	cache->c_max = 0;
+	cache->c_hits = 0;
+	cache->c_misses = 0;
+	cache->c_maxcount = maxcount;
+	cache->c_hashsize = hashsize;
+	cache->c_hashshift = fls(hashsize) - 1;
+	cache->hash = cache_operations->hash;
+	cache->alloc = cache_operations->alloc;
+	cache->flush = cache_operations->flush;
+	cache->relse = cache_operations->relse;
+	cache->compare = cache_operations->compare;
+	cache->bulkrelse = cache_operations->bulkrelse ?
+		cache_operations->bulkrelse : cache_generic_bulkrelse;
+	cache->get = cache_operations->get;
+	cache->put = cache_operations->put;
+	pthread_mutex_init(&cache->c_mutex, NULL);
+
+	for (i = 0; i < hashsize; i++) {
+		list_head_init(&cache->c_hash[i].ch_list);
+		cache->c_hash[i].ch_count = 0;
+		pthread_mutex_init(&cache->c_hash[i].ch_mutex, NULL);
+	}
+
+	for (i = 0; i <= CACHE_DIRTY_PRIORITY; i++) {
+		list_head_init(&cache->c_mrus[i].cm_list);
+		cache->c_mrus[i].cm_count = 0;
+		pthread_mutex_init(&cache->c_mrus[i].cm_mutex, NULL);
+	}
+	return cache;
+}
+
+static void
+cache_expand(
+	struct cache *		cache)
+{
+	pthread_mutex_lock(&cache->c_mutex);
+#ifdef CACHE_DEBUG
+	fprintf(stderr, "doubling cache size to %d\n", 2 * cache->c_maxcount);
+#endif
+	cache->c_maxcount *= 2;
+	pthread_mutex_unlock(&cache->c_mutex);
+}
+
+void
+cache_walk(
+	struct cache *		cache,
+	cache_walk_t		visit)
+{
+	struct cache_hash *	hash;
+	struct list_head *	head;
+	struct list_head *	pos;
+	unsigned int		i;
+
+	for (i = 0; i < cache->c_hashsize; i++) {
+		hash = &cache->c_hash[i];
+		head = &hash->ch_list;
+		pthread_mutex_lock(&hash->ch_mutex);
+		for (pos = head->next; pos != head; pos = pos->next)
+			visit((struct cache_node *)pos);
+		pthread_mutex_unlock(&hash->ch_mutex);
+	}
+}
+
+#ifdef CACHE_ABORT
+#define cache_abort()	abort()
+#else
+#define cache_abort()	do { } while (0)
+#endif
+
+#ifdef CACHE_DEBUG
+static void
+cache_zero_check(
+	struct cache_node *	node)
+{
+	if (node->cn_count > 0) {
+		fprintf(stderr, "%s: refcount is %u, not zero (node=%p)\n",
+			__FUNCTION__, node->cn_count, node);
+		cache_abort();
+	}
+}
+#define cache_destroy_check(c)	cache_walk((c), cache_zero_check)
+#else
+#define cache_destroy_check(c)	do { } while (0)
+#endif
+
+void
+cache_destroy(
+	struct cache *		cache)
+{
+	unsigned int		i;
+
+	cache_destroy_check(cache);
+	for (i = 0; i < cache->c_hashsize; i++) {
+		list_head_destroy(&cache->c_hash[i].ch_list);
+		pthread_mutex_destroy(&cache->c_hash[i].ch_mutex);
+	}
+	for (i = 0; i <= CACHE_DIRTY_PRIORITY; i++) {
+		list_head_destroy(&cache->c_mrus[i].cm_list);
+		pthread_mutex_destroy(&cache->c_mrus[i].cm_mutex);
+	}
+	pthread_mutex_destroy(&cache->c_mutex);
+	free(cache->c_hash);
+	free(cache);
+}
+
+static unsigned int
+cache_generic_bulkrelse(
+	struct cache *		cache,
+	struct list_head *	list)
+{
+	struct cache_node *	node;
+	unsigned int		count = 0;
+
+	while (!list_empty(list)) {
+		node = list_entry(list->next, struct cache_node, cn_mru);
+		pthread_mutex_destroy(&node->cn_mutex);
+		list_del_init(&node->cn_mru);
+		cache->relse(node);
+		count++;
+	}
+
+	return count;
+}
+
+/*
+ * Park unflushable nodes on their own special MRU so that cache_shake() doesn't
+ * end up repeatedly scanning them in the futile attempt to clean them before
+ * reclaim.
+ */
+static void
+cache_add_to_dirty_mru(
+	struct cache		*cache,
+	struct cache_node	*node)
+{
+	struct cache_mru	*mru = &cache->c_mrus[CACHE_DIRTY_PRIORITY];
+
+	pthread_mutex_lock(&mru->cm_mutex);
+	node->cn_old_priority = node->cn_priority;
+	node->cn_priority = CACHE_DIRTY_PRIORITY;
+	list_add(&node->cn_mru, &mru->cm_list);
+	mru->cm_count++;
+	pthread_mutex_unlock(&mru->cm_mutex);
+}
+
+/*
+ * We've hit the limit on cache size, so we need to start reclaiming nodes we've
+ * used. The MRU specified by the priority is shaken.  Returns new priority at
+ * end of the call (in case we call again). We are not allowed to reclaim dirty
+ * objects, so we have to flush them first. If flushing fails, we move them to
+ * the "dirty, unreclaimable" list.
+ *
+ * Hence we skip priorities > CACHE_MAX_PRIORITY unless "purge" is set as we
+ * park unflushable (and hence unreclaimable) buffers at these priorities.
+ * Trying to shake unreclaimable buffer lists when there is memory pressure is a
+ * waste of time and CPU and greatly slows down cache node recycling operations.
+ * Hence we only try to free them if we are being asked to purge the cache of
+ * all entries.
+ */
+static unsigned int
+cache_shake(
+	struct cache *		cache,
+	unsigned int		priority,
+	bool			purge)
+{
+	struct cache_mru	*mru;
+	struct cache_hash *	hash;
+	struct list_head	temp;
+	struct list_head *	head;
+	struct list_head *	pos;
+	struct list_head *	n;
+	struct cache_node *	node;
+	unsigned int		count;
+
+	ASSERT(priority <= CACHE_DIRTY_PRIORITY);
+	if (priority > CACHE_MAX_PRIORITY && !purge)
+		priority = 0;
+
+	mru = &cache->c_mrus[priority];
+	count = 0;
+	list_head_init(&temp);
+	head = &mru->cm_list;
+
+	pthread_mutex_lock(&mru->cm_mutex);
+	for (pos = head->prev, n = pos->prev; pos != head;
+						pos = n, n = pos->prev) {
+		node = list_entry(pos, struct cache_node, cn_mru);
+
+		if (pthread_mutex_trylock(&node->cn_mutex) != 0)
+			continue;
+
+		/* memory pressure is not allowed to release dirty objects */
+		if (cache->flush(node) && !purge) {
+			list_del(&node->cn_mru);
+			mru->cm_count--;
+			node->cn_priority = -1;
+			pthread_mutex_unlock(&node->cn_mutex);
+			cache_add_to_dirty_mru(cache, node);
+			continue;
+		}
+
+		hash = cache->c_hash + node->cn_hashidx;
+		if (pthread_mutex_trylock(&hash->ch_mutex) != 0) {
+			pthread_mutex_unlock(&node->cn_mutex);
+			continue;
+		}
+		ASSERT(node->cn_count == 0);
+		ASSERT(node->cn_priority == priority);
+		node->cn_priority = -1;
+
+		list_move(&node->cn_mru, &temp);
+		list_del_init(&node->cn_hash);
+		hash->ch_count--;
+		mru->cm_count--;
+		pthread_mutex_unlock(&hash->ch_mutex);
+		pthread_mutex_unlock(&node->cn_mutex);
+
+		count++;
+		if (!purge && count == CACHE_SHAKE_COUNT)
+			break;
+	}
+	pthread_mutex_unlock(&mru->cm_mutex);
+
+	if (count > 0) {
+		cache->bulkrelse(cache, &temp);
+
+		pthread_mutex_lock(&cache->c_mutex);
+		cache->c_count -= count;
+		pthread_mutex_unlock(&cache->c_mutex);
+	}
+
+	return (count == CACHE_SHAKE_COUNT) ? priority : ++priority;
+}
+
+/*
+ * Allocate a new hash node (updating atomic counter in the process),
+ * unless doing so will push us over the maximum cache size.
+ */
+static struct cache_node *
+cache_node_allocate(
+	struct cache *		cache,
+	cache_key_t		key)
+{
+	unsigned int		nodesfree;
+	struct cache_node *	node;
+
+	pthread_mutex_lock(&cache->c_mutex);
+	nodesfree = (cache->c_count < cache->c_maxcount);
+	if (nodesfree) {
+		cache->c_count++;
+		if (cache->c_count > cache->c_max)
+			cache->c_max = cache->c_count;
+	}
+	cache->c_misses++;
+	pthread_mutex_unlock(&cache->c_mutex);
+	if (!nodesfree)
+		return NULL;
+	node = cache->alloc(key);
+	if (node == NULL) {	/* uh-oh */
+		pthread_mutex_lock(&cache->c_mutex);
+		cache->c_count--;
+		pthread_mutex_unlock(&cache->c_mutex);
+		return NULL;
+	}
+	pthread_mutex_init(&node->cn_mutex, NULL);
+	list_head_init(&node->cn_mru);
+	node->cn_count = 1;
+	node->cn_priority = 0;
+	node->cn_old_priority = -1;
+	return node;
+}
+
+int
+cache_overflowed(
+	struct cache *		cache)
+{
+	return cache->c_maxcount == cache->c_max;
+}
+
+
+static int
+__cache_node_purge(
+	struct cache *		cache,
+	struct cache_node *	node)
+{
+	int			count;
+	struct cache_mru *	mru;
+
+	pthread_mutex_lock(&node->cn_mutex);
+	count = node->cn_count;
+	if (count != 0) {
+		pthread_mutex_unlock(&node->cn_mutex);
+		return count;
+	}
+
+	/* can't purge dirty objects */
+	if (cache->flush(node)) {
+		pthread_mutex_unlock(&node->cn_mutex);
+		return 1;
+	}
+
+	mru = &cache->c_mrus[node->cn_priority];
+	pthread_mutex_lock(&mru->cm_mutex);
+	list_del_init(&node->cn_mru);
+	mru->cm_count--;
+	pthread_mutex_unlock(&mru->cm_mutex);
+
+	pthread_mutex_unlock(&node->cn_mutex);
+	pthread_mutex_destroy(&node->cn_mutex);
+	list_del_init(&node->cn_hash);
+	cache->relse(node);
+	return 0;
+}
+
+/*
+ * Lookup in the cache hash table.  With any luck we'll get a cache
+ * hit, in which case this will all be over quickly and painlessly.
+ * Otherwise, we allocate a new node, taking care not to expand the
+ * cache beyond the requested maximum size (shrink it if it would).
+ * Returns one if hit in cache, otherwise zero.  A node is _always_
+ * returned, however.
+ */
+int
+cache_node_get(
+	struct cache *		cache,
+	cache_key_t		key,
+	struct cache_node **	nodep)
+{
+	struct cache_node *	node = NULL;
+	struct cache_hash *	hash;
+	struct cache_mru *	mru;
+	struct list_head *	head;
+	struct list_head *	pos;
+	struct list_head *	n;
+	unsigned int		hashidx;
+	int			priority = 0;
+	int			purged = 0;
+
+	hashidx = cache->hash(key, cache->c_hashsize, cache->c_hashshift);
+	hash = cache->c_hash + hashidx;
+	head = &hash->ch_list;
+
+	for (;;) {
+		pthread_mutex_lock(&hash->ch_mutex);
+		for (pos = head->next, n = pos->next; pos != head;
+						pos = n, n = pos->next) {
+			int result;
+
+			node = list_entry(pos, struct cache_node, cn_hash);
+			result = cache->compare(node, key);
+			switch (result) {
+			case CACHE_HIT:
+				break;
+			case CACHE_PURGE:
+				if ((cache->c_flags & CACHE_MISCOMPARE_PURGE) &&
+				    !__cache_node_purge(cache, node)) {
+					purged++;
+					hash->ch_count--;
+				}
+				/* FALL THROUGH */
+			case CACHE_MISS:
+				goto next_object;
+			}
+
+			/*
+			 * node found, bump node's reference count, remove it
+			 * from its MRU list, and update stats.
+			 */
+			pthread_mutex_lock(&node->cn_mutex);
+
+			if (node->cn_count == 0 && cache->get) {
+				int err = cache->get(node);
+				if (err) {
+					pthread_mutex_unlock(&node->cn_mutex);
+					goto next_object;
+				}
+			}
+			if (node->cn_count == 0) {
+				ASSERT(node->cn_priority >= 0);
+				ASSERT(!list_empty(&node->cn_mru));
+				mru = &cache->c_mrus[node->cn_priority];
+				pthread_mutex_lock(&mru->cm_mutex);
+				mru->cm_count--;
+				list_del_init(&node->cn_mru);
+				pthread_mutex_unlock(&mru->cm_mutex);
+				if (node->cn_old_priority != -1) {
+					ASSERT(node->cn_priority ==
+							CACHE_DIRTY_PRIORITY);
+					node->cn_priority = node->cn_old_priority;
+					node->cn_old_priority = -1;
+				}
+			}
+			node->cn_count++;
+
+			pthread_mutex_unlock(&node->cn_mutex);
+			pthread_mutex_unlock(&hash->ch_mutex);
+
+			pthread_mutex_lock(&cache->c_mutex);
+			cache->c_hits++;
+			pthread_mutex_unlock(&cache->c_mutex);
+
+			*nodep = node;
+			return 0;
+next_object:
+			continue;	/* what the hell, gcc? */
+		}
+		pthread_mutex_unlock(&hash->ch_mutex);
+		/*
+		 * not found, allocate a new entry
+		 */
+		node = cache_node_allocate(cache, key);
+		if (node)
+			break;
+		priority = cache_shake(cache, priority, false);
+		/*
+		 * We start at 0; if we free CACHE_SHAKE_COUNT we get
+		 * back the same priority, if not we get back priority+1.
+		 * If we exceed CACHE_MAX_PRIORITY all slots are full; grow it.
+		 */
+		if (priority > CACHE_MAX_PRIORITY) {
+			priority = 0;
+			cache_expand(cache);
+		}
+	}
+
+	node->cn_hashidx = hashidx;
+
+	/* add new node to appropriate hash */
+	pthread_mutex_lock(&hash->ch_mutex);
+	hash->ch_count++;
+	list_add(&node->cn_hash, &hash->ch_list);
+	pthread_mutex_unlock(&hash->ch_mutex);
+
+	if (purged) {
+		pthread_mutex_lock(&cache->c_mutex);
+		cache->c_count -= purged;
+		pthread_mutex_unlock(&cache->c_mutex);
+	}
+
+	*nodep = node;
+	return 1;
+}
+
+void
+cache_node_put(
+	struct cache *		cache,
+	struct cache_node *	node)
+{
+	struct cache_mru *	mru;
+
+	pthread_mutex_lock(&node->cn_mutex);
+#ifdef CACHE_DEBUG
+	if (node->cn_count < 1) {
+		fprintf(stderr, "%s: node put on refcount %u (node=%p)\n",
+				__FUNCTION__, node->cn_count, node);
+		cache_abort();
+	}
+	if (!list_empty(&node->cn_mru)) {
+		fprintf(stderr, "%s: node put on node (%p) in MRU list\n",
+				__FUNCTION__, node);
+		cache_abort();
+	}
+#endif
+	node->cn_count--;
+
+	if (node->cn_count == 0 && cache->put)
+		cache->put(node);
+	if (node->cn_count == 0) {
+		/* add unreferenced node to appropriate MRU for shaker */
+		mru = &cache->c_mrus[node->cn_priority];
+		pthread_mutex_lock(&mru->cm_mutex);
+		mru->cm_count++;
+		list_add(&node->cn_mru, &mru->cm_list);
+		pthread_mutex_unlock(&mru->cm_mutex);
+	}
+
+	pthread_mutex_unlock(&node->cn_mutex);
+}
+
+void
+cache_node_set_priority(
+	struct cache *		cache,
+	struct cache_node *	node,
+	int			priority)
+{
+	if (priority < 0)
+		priority = 0;
+	else if (priority > CACHE_MAX_PRIORITY)
+		priority = CACHE_MAX_PRIORITY;
+
+	pthread_mutex_lock(&node->cn_mutex);
+	ASSERT(node->cn_count > 0);
+	node->cn_priority = priority;
+	node->cn_old_priority = -1;
+	pthread_mutex_unlock(&node->cn_mutex);
+}
+
+int
+cache_node_get_priority(
+	struct cache_node *	node)
+{
+	int			priority;
+
+	pthread_mutex_lock(&node->cn_mutex);
+	priority = node->cn_priority;
+	pthread_mutex_unlock(&node->cn_mutex);
+
+	return priority;
+}
+
+
+/*
+ * Purge a specific node from the cache.  Reference count must be zero.
+ */
+int
+cache_node_purge(
+	struct cache *		cache,
+	cache_key_t		key,
+	struct cache_node *	node)
+{
+	struct list_head *	head;
+	struct list_head *	pos;
+	struct list_head *	n;
+	struct cache_hash *	hash;
+	int			count = -1;
+
+	hash = cache->c_hash + cache->hash(key, cache->c_hashsize,
+					   cache->c_hashshift);
+	head = &hash->ch_list;
+	pthread_mutex_lock(&hash->ch_mutex);
+	for (pos = head->next, n = pos->next; pos != head;
+						pos = n, n = pos->next) {
+		if ((struct cache_node *)pos != node)
+			continue;
+
+		count = __cache_node_purge(cache, node);
+		if (!count)
+			hash->ch_count--;
+		break;
+	}
+	pthread_mutex_unlock(&hash->ch_mutex);
+
+	if (count == 0) {
+		pthread_mutex_lock(&cache->c_mutex);
+		cache->c_count--;
+		pthread_mutex_unlock(&cache->c_mutex);
+	}
+#ifdef CACHE_DEBUG
+	if (count >= 1) {
+		fprintf(stderr, "%s: refcount was %u, not zero (node=%p)\n",
+				__FUNCTION__, count, node);
+		cache_abort();
+	}
+	if (count == -1) {
+		fprintf(stderr, "%s: purge node not found! (node=%p)\n",
+			__FUNCTION__, node);
+		cache_abort();
+	}
+#endif
+	return count == 0;
+}
+
+/*
+ * Purge all nodes from the cache.  All reference counts must be zero.
+ */
+void
+cache_purge(
+	struct cache *		cache)
+{
+	int			i;
+
+	for (i = 0; i <= CACHE_DIRTY_PRIORITY; i++)
+		cache_shake(cache, i, true);
+
+#ifdef CACHE_DEBUG
+	if (cache->c_count != 0) {
+		/* flush referenced nodes to disk */
+		cache_flush(cache);
+		fprintf(stderr, "%s: shake on cache %p left %u nodes!?\n",
+				__FUNCTION__, cache, cache->c_count);
+		cache_abort();
+	}
+#endif
+}
+
+/*
+ * Flush all nodes in the cache to disk.
+ */
+void
+cache_flush(
+	struct cache *		cache)
+{
+	struct cache_hash *	hash;
+	struct list_head *	head;
+	struct list_head *	pos;
+	struct cache_node *	node;
+	int			i;
+
+	if (!cache->flush)
+		return;
+
+	for (i = 0; i < cache->c_hashsize; i++) {
+		hash = &cache->c_hash[i];
+
+		pthread_mutex_lock(&hash->ch_mutex);
+		head = &hash->ch_list;
+		for (pos = head->next; pos != head; pos = pos->next) {
+			node = (struct cache_node *)pos;
+			pthread_mutex_lock(&node->cn_mutex);
+			cache->flush(node);
+			pthread_mutex_unlock(&node->cn_mutex);
+		}
+		pthread_mutex_unlock(&hash->ch_mutex);
+	}
+}
+
+#define	HASH_REPORT	(3 * HASH_CACHE_RATIO)
+void
+cache_report(
+	FILE		*fp,
+	const char	*name,
+	struct cache	*cache)
+{
+	int		i;
+	unsigned long	count, index, total;
+	unsigned long	hash_bucket_lengths[HASH_REPORT + 2];
+
+	if ((cache->c_hits + cache->c_misses) == 0)
+		return;
+
+	/* report cache summary */
+	fprintf(fp, "%s: %p\n"
+			"Max supported entries = %u\n"
+			"Max utilized entries = %u\n"
+			"Active entries = %u\n"
+			"Hash table size = %u\n"
+			"Hits = %llu\n"
+			"Misses = %llu\n"
+			"Hit ratio = %5.2f\n",
+			name, cache,
+			cache->c_maxcount,
+			cache->c_max,
+			cache->c_count,
+			cache->c_hashsize,
+			cache->c_hits,
+			cache->c_misses,
+			(double)cache->c_hits * 100 /
+				(cache->c_hits + cache->c_misses)
+	);
+
+	for (i = 0; i <= CACHE_MAX_PRIORITY; i++)
+		fprintf(fp, "MRU %d entries = %6u (%3u%%)\n",
+			i, cache->c_mrus[i].cm_count,
+			cache->c_mrus[i].cm_count * 100 / cache->c_count);
+
+	i = CACHE_DIRTY_PRIORITY;
+	fprintf(fp, "Dirty MRU %d entries = %6u (%3u%%)\n",
+		i, cache->c_mrus[i].cm_count,
+		cache->c_mrus[i].cm_count * 100 / cache->c_count);
+
+	/* report hash bucket lengths */
+	bzero(hash_bucket_lengths, sizeof(hash_bucket_lengths));
+
+	for (i = 0; i < cache->c_hashsize; i++) {
+		count = cache->c_hash[i].ch_count;
+		if (count > HASH_REPORT)
+			index = HASH_REPORT + 1;
+		else
+			index = count;
+		hash_bucket_lengths[index]++;
+	}
+
+	total = 0;
+	for (i = 0; i < HASH_REPORT + 1; i++) {
+		total += i * hash_bucket_lengths[i];
+		if (hash_bucket_lengths[i] == 0)
+			continue;
+		fprintf(fp, "Hash buckets with  %2d entries %6ld (%3ld%%)\n",
+			i, hash_bucket_lengths[i],
+			(i * hash_bucket_lengths[i] * 100) / cache->c_count);
+	}
+	if (hash_bucket_lengths[i])	/* last report bucket is the overflow bucket */
+		fprintf(fp, "Hash buckets with >%2d entries %6ld (%3ld%%)\n",
+			i - 1, hash_bucket_lengths[i],
+			((cache->c_count - total) * 100) / cache->c_count);
+}

[PATCH 08/21] cache: disable debugging

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Not sure why debugging is turned on by default in the xfsprogs cache
code, but let's turn it off.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)


diff --git a/lib/support/cache.c b/lib/support/cache.c
index fe04f62f262aaa..08e0b484cca298 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -17,9 +17,8 @@
 #include "cache.h"
 #include "xbitops.h"
 
-#define CACHE_DEBUG 1
 #undef CACHE_DEBUG
-#define CACHE_DEBUG 1
+/* #define CACHE_DEBUG 1 */
 #undef CACHE_ABORT
 /* #define CACHE_ABORT 1 */
 
@@ -28,6 +27,8 @@
 #ifdef CACHE_DEBUG
 # include <assert.h>
 # define ASSERT(x)		assert(x)
+#else
+# define ASSERT(x)		do { } while (0)
 #endif
 
 static unsigned int cache_generic_bulkrelse(struct cache *, struct list_head *);

[PATCH 09/21] cache: use modern list iterator macros

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Use the list iterator macros from list.h.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.c |   71 +++++++++++++++++----------------------------------
 1 file changed, 24 insertions(+), 47 deletions(-)


diff --git a/lib/support/cache.c b/lib/support/cache.c
index 08e0b484cca298..d8f8231ac36d28 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -98,20 +98,18 @@ cache_expand(
 
 void
 cache_walk(
-	struct cache *		cache,
+	struct cache		*cache,
 	cache_walk_t		visit)
 {
-	struct cache_hash *	hash;
-	struct list_head *	head;
-	struct list_head *	pos;
+	struct cache_hash	*hash;
+	struct cache_node	*pos;
 	unsigned int		i;
 
 	for (i = 0; i < cache->c_hashsize; i++) {
 		hash = &cache->c_hash[i];
-		head = &hash->ch_list;
 		pthread_mutex_lock(&hash->ch_mutex);
-		for (pos = head->next; pos != head; pos = pos->next)
-			visit((struct cache_node *)pos);
+		list_for_each_entry(pos, &hash->ch_list, cn_hash)
+			visit(pos);
 		pthread_mutex_unlock(&hash->ch_mutex);
 	}
 }
@@ -218,12 +216,9 @@ cache_shake(
 	bool			purge)
 {
 	struct cache_mru	*mru;
-	struct cache_hash *	hash;
+	struct cache_hash	*hash;
 	struct list_head	temp;
-	struct list_head *	head;
-	struct list_head *	pos;
-	struct list_head *	n;
-	struct cache_node *	node;
+	struct cache_node	*node, *n;
 	unsigned int		count;
 
 	ASSERT(priority <= CACHE_DIRTY_PRIORITY);
@@ -233,13 +228,9 @@ cache_shake(
 	mru = &cache->c_mrus[priority];
 	count = 0;
 	list_head_init(&temp);
-	head = &mru->cm_list;
 
 	pthread_mutex_lock(&mru->cm_mutex);
-	for (pos = head->prev, n = pos->prev; pos != head;
-						pos = n, n = pos->prev) {
-		node = list_entry(pos, struct cache_node, cn_mru);
-
+	list_for_each_entry_safe_reverse(node, n, &mru->cm_list, cn_mru) {
 		if (pthread_mutex_trylock(&node->cn_mutex) != 0)
 			continue;
 
@@ -376,31 +367,25 @@ __cache_node_purge(
  */
 int
 cache_node_get(
-	struct cache *		cache,
+	struct cache		*cache,
 	cache_key_t		key,
-	struct cache_node **	nodep)
+	struct cache_node	**nodep)
 {
-	struct cache_node *	node = NULL;
-	struct cache_hash *	hash;
-	struct cache_mru *	mru;
-	struct list_head *	head;
-	struct list_head *	pos;
-	struct list_head *	n;
+	struct cache_hash	*hash;
+	struct cache_mru	*mru;
+	struct cache_node	*node = NULL, *n;
 	unsigned int		hashidx;
 	int			priority = 0;
 	int			purged = 0;
 
 	hashidx = cache->hash(key, cache->c_hashsize, cache->c_hashshift);
 	hash = cache->c_hash + hashidx;
-	head = &hash->ch_list;
 
 	for (;;) {
 		pthread_mutex_lock(&hash->ch_mutex);
-		for (pos = head->next, n = pos->next; pos != head;
-						pos = n, n = pos->next) {
+		list_for_each_entry_safe(node, n, &hash->ch_list, cn_hash) {
 			int result;
 
-			node = list_entry(pos, struct cache_node, cn_hash);
 			result = cache->compare(node, key);
 			switch (result) {
 			case CACHE_HIT:
@@ -568,23 +553,19 @@ cache_node_get_priority(
  */
 int
 cache_node_purge(
-	struct cache *		cache,
+	struct cache		*cache,
 	cache_key_t		key,
-	struct cache_node *	node)
+	struct cache_node	*node)
 {
-	struct list_head *	head;
-	struct list_head *	pos;
-	struct list_head *	n;
-	struct cache_hash *	hash;
+	struct cache_node	*pos, *n;
+	struct cache_hash	*hash;
 	int			count = -1;
 
 	hash = cache->c_hash + cache->hash(key, cache->c_hashsize,
 					   cache->c_hashshift);
-	head = &hash->ch_list;
 	pthread_mutex_lock(&hash->ch_mutex);
-	for (pos = head->next, n = pos->next; pos != head;
-						pos = n, n = pos->next) {
-		if ((struct cache_node *)pos != node)
+	list_for_each_entry_safe(pos, n, &hash->ch_list, cn_hash) {
+		if (pos != node)
 			continue;
 
 		count = __cache_node_purge(cache, node);
@@ -642,12 +623,10 @@ cache_purge(
  */
 void
 cache_flush(
-	struct cache *		cache)
+	struct cache		*cache)
 {
-	struct cache_hash *	hash;
-	struct list_head *	head;
-	struct list_head *	pos;
-	struct cache_node *	node;
+	struct cache_hash	*hash;
+	struct cache_node	*node;
 	int			i;
 
 	if (!cache->flush)
@@ -657,9 +636,7 @@ cache_flush(
 		hash = &cache->c_hash[i];
 
 		pthread_mutex_lock(&hash->ch_mutex);
-		head = &hash->ch_list;
-		for (pos = head->next; pos != head; pos = pos->next) {
-			node = (struct cache_node *)pos;
+		list_for_each_entry(node, &hash->ch_list, cn_hash) {
 			pthread_mutex_lock(&node->cn_mutex);
 			cache->flush(node);
 			pthread_mutex_unlock(&node->cn_mutex);

[PATCH 10/21] cache: embed struct cache in the owner

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

It'll be easier to embed a struct cache into the object that owns the
cache rather than passing pointers around.  This is the prelude to the
next patch, which will enable cache functions to walk back to the owning
struct.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |   10 ++++++++--
 lib/support/cache.c |   38 ++++++++++++++++++++------------------
 2 files changed, 28 insertions(+), 20 deletions(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index 16b17a9b7a1a51..993f1385dedcee 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -122,8 +122,14 @@ struct cache {
 	unsigned int 		c_max;		/* max nodes ever used */
 };
 
-struct cache *cache_init(int, unsigned int, const struct cache_operations *);
-void cache_destroy(struct cache *);
+static inline bool cache_initialized(const struct cache *cache)
+{
+	return cache->hash != NULL;
+}
+
+int cache_init(int flags, unsigned int size,
+	       const struct cache_operations *ops, struct cache *cache);
+void cache_destroy(struct cache *cache);
 void cache_walk(struct cache *, cache_walk_t);
 void cache_purge(struct cache *);
 void cache_flush(struct cache *);
diff --git a/lib/support/cache.c b/lib/support/cache.c
index d8f8231ac36d28..8b4f9f03c3899b 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -12,6 +12,7 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <errno.h>
 
 #include "list.h"
 #include "cache.h"
@@ -33,23 +34,18 @@
 
 static unsigned int cache_generic_bulkrelse(struct cache *, struct list_head *);
 
-struct cache *
+int
 cache_init(
 	int			flags,
 	unsigned int		hashsize,
-	const struct cache_operations	*cache_operations)
+	const struct cache_operations	*cache_operations,
+	struct cache		*cache)
 {
-	struct cache *		cache;
 	unsigned int		i, maxcount;
 
 	maxcount = hashsize * HASH_CACHE_RATIO;
 
-	if (!(cache = malloc(sizeof(struct cache))))
-		return NULL;
-	if (!(cache->c_hash = calloc(hashsize, sizeof(struct cache_hash)))) {
-		free(cache);
-		return NULL;
-	}
+	memset(cache, 0, sizeof(*cache));
 
 	cache->c_flags = flags;
 	cache->c_count = 0;
@@ -57,8 +53,6 @@ cache_init(
 	cache->c_hits = 0;
 	cache->c_misses = 0;
 	cache->c_maxcount = maxcount;
-	cache->c_hashsize = hashsize;
-	cache->c_hashshift = fls(hashsize) - 1;
 	cache->hash = cache_operations->hash;
 	cache->alloc = cache_operations->alloc;
 	cache->flush = cache_operations->flush;
@@ -70,18 +64,26 @@ cache_init(
 	cache->put = cache_operations->put;
 	pthread_mutex_init(&cache->c_mutex, NULL);
 
+	for (i = 0; i <= CACHE_DIRTY_PRIORITY; i++) {
+		list_head_init(&cache->c_mrus[i].cm_list);
+		cache->c_mrus[i].cm_count = 0;
+		pthread_mutex_init(&cache->c_mrus[i].cm_mutex, NULL);
+	}
+
+	cache->c_hash = calloc(hashsize, sizeof(struct cache_hash));
+	if (!cache->c_hash)
+		return ENOMEM;
+
+	cache->c_hashsize = hashsize;
+	cache->c_hashshift = fls(hashsize) - 1;
+
 	for (i = 0; i < hashsize; i++) {
 		list_head_init(&cache->c_hash[i].ch_list);
 		cache->c_hash[i].ch_count = 0;
 		pthread_mutex_init(&cache->c_hash[i].ch_mutex, NULL);
 	}
 
-	for (i = 0; i <= CACHE_DIRTY_PRIORITY; i++) {
-		list_head_init(&cache->c_mrus[i].cm_list);
-		cache->c_mrus[i].cm_count = 0;
-		pthread_mutex_init(&cache->c_mrus[i].cm_mutex, NULL);
-	}
-	return cache;
+	return 0;
 }
 
 static void
@@ -153,7 +155,7 @@ cache_destroy(
 	}
 	pthread_mutex_destroy(&cache->c_mutex);
 	free(cache->c_hash);
-	free(cache);
+	memset(cache, 0, sizeof(*cache));
 }
 
 static unsigned int

[PATCH 11/21] cache: pass cache pointer to callbacks

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Pass the cache pointer to the cache node callbacks so that subsequent
patches don't have to waste memory putting pointers to struct fuse4fs in
the cached objects.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |   12 ++++++------
 lib/support/cache.c |   21 +++++++++++----------
 2 files changed, 17 insertions(+), 16 deletions(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index 993f1385dedcee..0168fdca027896 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -56,16 +56,16 @@ struct cache_node;
 
 typedef void *cache_key_t;
 
-typedef void (*cache_walk_t)(struct cache_node *);
-typedef struct cache_node * (*cache_node_alloc_t)(cache_key_t);
-typedef int (*cache_node_flush_t)(struct cache_node *);
-typedef void (*cache_node_relse_t)(struct cache_node *);
+typedef void (*cache_walk_t)(struct cache *c, struct cache_node *cn);
+typedef struct cache_node * (*cache_node_alloc_t)(struct cache *c, cache_key_t k);
+typedef int (*cache_node_flush_t)(struct cache *c, struct cache_node *cn);
+typedef void (*cache_node_relse_t)(struct cache *c, struct cache_node *cn);
 typedef unsigned int (*cache_node_hash_t)(cache_key_t, unsigned int,
 					  unsigned int);
 typedef int (*cache_node_compare_t)(struct cache_node *, cache_key_t);
 typedef unsigned int (*cache_bulk_relse_t)(struct cache *, struct list_head *);
-typedef int (*cache_node_get_t)(struct cache_node *);
-typedef void (*cache_node_put_t)(struct cache_node *);
+typedef int (*cache_node_get_t)(struct cache *c, struct cache_node *cn);
+typedef void (*cache_node_put_t)(struct cache *c, struct cache_node *cn);
 
 struct cache_operations {
 	cache_node_hash_t	hash;
diff --git a/lib/support/cache.c b/lib/support/cache.c
index 8b4f9f03c3899b..2e2e36ccc3ef78 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -111,7 +111,7 @@ cache_walk(
 		hash = &cache->c_hash[i];
 		pthread_mutex_lock(&hash->ch_mutex);
 		list_for_each_entry(pos, &hash->ch_list, cn_hash)
-			visit(pos);
+			visit(cache, pos);
 		pthread_mutex_unlock(&hash->ch_mutex);
 	}
 }
@@ -125,7 +125,8 @@ cache_walk(
 #ifdef CACHE_DEBUG
 static void
 cache_zero_check(
-	struct cache_node *	node)
+	struct cache		*cache,
+	struct cache_node	*node)
 {
 	if (node->cn_count > 0) {
 		fprintf(stderr, "%s: refcount is %u, not zero (node=%p)\n",
@@ -170,7 +171,7 @@ cache_generic_bulkrelse(
 		node = list_entry(list->next, struct cache_node, cn_mru);
 		pthread_mutex_destroy(&node->cn_mutex);
 		list_del_init(&node->cn_mru);
-		cache->relse(node);
+		cache->relse(cache, node);
 		count++;
 	}
 
@@ -237,7 +238,7 @@ cache_shake(
 			continue;
 
 		/* memory pressure is not allowed to release dirty objects */
-		if (cache->flush(node) && !purge) {
+		if (cache->flush(cache, node) && !purge) {
 			list_del(&node->cn_mru);
 			mru->cm_count--;
 			node->cn_priority = -1;
@@ -302,7 +303,7 @@ cache_node_allocate(
 	pthread_mutex_unlock(&cache->c_mutex);
 	if (!nodesfree)
 		return NULL;
-	node = cache->alloc(key);
+	node = cache->alloc(cache, key);
 	if (node == NULL) {	/* uh-oh */
 		pthread_mutex_lock(&cache->c_mutex);
 		cache->c_count--;
@@ -341,7 +342,7 @@ __cache_node_purge(
 	}
 
 	/* can't purge dirty objects */
-	if (cache->flush(node)) {
+	if (cache->flush(cache, node)) {
 		pthread_mutex_unlock(&node->cn_mutex);
 		return 1;
 	}
@@ -355,7 +356,7 @@ __cache_node_purge(
 	pthread_mutex_unlock(&node->cn_mutex);
 	pthread_mutex_destroy(&node->cn_mutex);
 	list_del_init(&node->cn_hash);
-	cache->relse(node);
+	cache->relse(cache, node);
 	return 0;
 }
 
@@ -410,7 +411,7 @@ cache_node_get(
 			pthread_mutex_lock(&node->cn_mutex);
 
 			if (node->cn_count == 0 && cache->get) {
-				int err = cache->get(node);
+				int err = cache->get(cache, node);
 				if (err) {
 					pthread_mutex_unlock(&node->cn_mutex);
 					goto next_object;
@@ -505,7 +506,7 @@ cache_node_put(
 	node->cn_count--;
 
 	if (node->cn_count == 0 && cache->put)
-		cache->put(node);
+		cache->put(cache, node);
 	if (node->cn_count == 0) {
 		/* add unreferenced node to appropriate MRU for shaker */
 		mru = &cache->c_mrus[node->cn_priority];
@@ -640,7 +641,7 @@ cache_flush(
 		pthread_mutex_lock(&hash->ch_mutex);
 		list_for_each_entry(node, &hash->ch_list, cn_hash) {
 			pthread_mutex_lock(&node->cn_mutex);
-			cache->flush(node);
+			cache->flush(cache, node);
 			pthread_mutex_unlock(&node->cn_mutex);
 		}
 		pthread_mutex_unlock(&hash->ch_mutex);

[PATCH 12/21] cache: pass a private data pointer through cache_walk

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Allow cache_walk callers to pass a pointer to the callback function.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |    4 ++--
 lib/support/cache.c |   10 ++++++----
 2 files changed, 8 insertions(+), 6 deletions(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index 0168fdca027896..b18b6d3325e9ad 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -56,7 +56,7 @@ struct cache_node;
 
 typedef void *cache_key_t;
 
-typedef void (*cache_walk_t)(struct cache *c, struct cache_node *cn);
+typedef void (*cache_walk_t)(struct cache *c, struct cache_node *cn, void *d);
 typedef struct cache_node * (*cache_node_alloc_t)(struct cache *c, cache_key_t k);
 typedef int (*cache_node_flush_t)(struct cache *c, struct cache_node *cn);
 typedef void (*cache_node_relse_t)(struct cache *c, struct cache_node *cn);
@@ -130,7 +130,7 @@ static inline bool cache_initialized(const struct cache *cache)
 int cache_init(int flags, unsigned int size,
 	       const struct cache_operations *ops, struct cache *cache);
 void cache_destroy(struct cache *cache);
-void cache_walk(struct cache *, cache_walk_t);
+void cache_walk(struct cache *cache, cache_walk_t fn, void *data);
 void cache_purge(struct cache *);
 void cache_flush(struct cache *);
 
diff --git a/lib/support/cache.c b/lib/support/cache.c
index 2e2e36ccc3ef78..606acd5453cf10 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -101,7 +101,8 @@ cache_expand(
 void
 cache_walk(
 	struct cache		*cache,
-	cache_walk_t		visit)
+	cache_walk_t		visit,
+	void			*data)
 {
 	struct cache_hash	*hash;
 	struct cache_node	*pos;
@@ -111,7 +112,7 @@ cache_walk(
 		hash = &cache->c_hash[i];
 		pthread_mutex_lock(&hash->ch_mutex);
 		list_for_each_entry(pos, &hash->ch_list, cn_hash)
-			visit(cache, pos);
+			visit(cache, pos, data);
 		pthread_mutex_unlock(&hash->ch_mutex);
 	}
 }
@@ -126,7 +127,8 @@ cache_walk(
 static void
 cache_zero_check(
 	struct cache		*cache,
-	struct cache_node	*node)
+	struct cache_node	*node,
+	void			*data)
 {
 	if (node->cn_count > 0) {
 		fprintf(stderr, "%s: refcount is %u, not zero (node=%p)\n",
@@ -134,7 +136,7 @@ cache_zero_check(
 		cache_abort();
 	}
 }
-#define cache_destroy_check(c)	cache_walk((c), cache_zero_check)
+#define cache_destroy_check(c)	cache_walk((c), cache_zero_check, NULL)
 #else
 #define cache_destroy_check(c)	do { } while (0)
 #endif

[PATCH 13/21] cache: add a helper to grab a new refcount for a cache_node

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create a helper to bump the refcount of a cache node.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |    1 +
 lib/support/cache.c |   57 +++++++++++++++++++++++++++++----------------------
 2 files changed, 33 insertions(+), 25 deletions(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index b18b6d3325e9ad..e8f1c82ef7869c 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -141,5 +141,6 @@ int cache_node_get_priority(struct cache_node *);
 int cache_node_purge(struct cache *, cache_key_t, struct cache_node *);
 void cache_report(FILE *fp, const char *, struct cache *);
 int cache_overflowed(struct cache *);
+struct cache_node *cache_node_grab(struct cache *cache, struct cache_node *node);
 
 #endif	/* __CACHE_H__ */
diff --git a/lib/support/cache.c b/lib/support/cache.c
index 606acd5453cf10..49568ffa6de2e4 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -362,6 +362,35 @@ __cache_node_purge(
 	return 0;
 }
 
+/* Grab a new refcount to the cache node object.  Caller must hold cn_mutex. */
+struct cache_node *cache_node_grab(struct cache *cache, struct cache_node *node)
+{
+	struct cache_mru *mru;
+
+	if (node->cn_count == 0 && cache->get) {
+		int err = cache->get(cache, node);
+		if (err)
+			return NULL;
+	}
+	if (node->cn_count == 0) {
+		ASSERT(node->cn_priority >= 0);
+		ASSERT(!list_empty(&node->cn_mru));
+		mru = &cache->c_mrus[node->cn_priority];
+		pthread_mutex_lock(&mru->cm_mutex);
+		mru->cm_count--;
+		list_del_init(&node->cn_mru);
+		pthread_mutex_unlock(&mru->cm_mutex);
+		if (node->cn_old_priority != -1) {
+			ASSERT(node->cn_priority ==
+					CACHE_DIRTY_PRIORITY);
+			node->cn_priority = node->cn_old_priority;
+			node->cn_old_priority = -1;
+		}
+	}
+	node->cn_count++;
+	return node;
+}
+
 /*
  * Lookup in the cache hash table.  With any luck we'll get a cache
  * hit, in which case this will all be over quickly and painlessly.
@@ -377,7 +406,6 @@ cache_node_get(
 	struct cache_node	**nodep)
 {
 	struct cache_hash	*hash;
-	struct cache_mru	*mru;
 	struct cache_node	*node = NULL, *n;
 	unsigned int		hashidx;
 	int			priority = 0;
@@ -411,31 +439,10 @@ cache_node_get(
 			 * from its MRU list, and update stats.
 			 */
 			pthread_mutex_lock(&node->cn_mutex);
-
-			if (node->cn_count == 0 && cache->get) {
-				int err = cache->get(cache, node);
-				if (err) {
-					pthread_mutex_unlock(&node->cn_mutex);
-					goto next_object;
-				}
+			if (!cache_node_grab(cache, node)) {
+				pthread_mutex_unlock(&node->cn_mutex);
+				goto next_object;
 			}
-			if (node->cn_count == 0) {
-				ASSERT(node->cn_priority >= 0);
-				ASSERT(!list_empty(&node->cn_mru));
-				mru = &cache->c_mrus[node->cn_priority];
-				pthread_mutex_lock(&mru->cm_mutex);
-				mru->cm_count--;
-				list_del_init(&node->cn_mru);
-				pthread_mutex_unlock(&mru->cm_mutex);
-				if (node->cn_old_priority != -1) {
-					ASSERT(node->cn_priority ==
-							CACHE_DIRTY_PRIORITY);
-					node->cn_priority = node->cn_old_priority;
-					node->cn_old_priority = -1;
-				}
-			}
-			node->cn_count++;
-
 			pthread_mutex_unlock(&node->cn_mutex);
 			pthread_mutex_unlock(&hash->ch_mutex);
 

[PATCH 14/21] cache: return results of a cache flush

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Modify cache_flush to return whether or not there were errors whilst
flushing the cache.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |    4 ++--
 lib/support/cache.c |   11 +++++++----
 2 files changed, 9 insertions(+), 6 deletions(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index e8f1c82ef7869c..8d39ca5c02a285 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -58,7 +58,7 @@ typedef void *cache_key_t;
 
 typedef void (*cache_walk_t)(struct cache *c, struct cache_node *cn, void *d);
 typedef struct cache_node * (*cache_node_alloc_t)(struct cache *c, cache_key_t k);
-typedef int (*cache_node_flush_t)(struct cache *c, struct cache_node *cn);
+typedef bool (*cache_node_flush_t)(struct cache *c, struct cache_node *cn);
 typedef void (*cache_node_relse_t)(struct cache *c, struct cache_node *cn);
 typedef unsigned int (*cache_node_hash_t)(cache_key_t, unsigned int,
 					  unsigned int);
@@ -132,7 +132,7 @@ int cache_init(int flags, unsigned int size,
 void cache_destroy(struct cache *cache);
 void cache_walk(struct cache *cache, cache_walk_t fn, void *data);
 void cache_purge(struct cache *);
-void cache_flush(struct cache *);
+bool cache_flush(struct cache *cache);
 
 int cache_node_get(struct cache *, cache_key_t, struct cache_node **);
 void cache_node_put(struct cache *, struct cache_node *);
diff --git a/lib/support/cache.c b/lib/support/cache.c
index 49568ffa6de2e4..fa07b4ad8222d2 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -631,18 +631,19 @@ cache_purge(
 }
 
 /*
- * Flush all nodes in the cache to disk.
+ * Flush all nodes in the cache to disk.  Returns true if the flush succeeded.
  */
-void
+bool
 cache_flush(
 	struct cache		*cache)
 {
 	struct cache_hash	*hash;
 	struct cache_node	*node;
 	int			i;
+	bool			still_dirty = false;
 
 	if (!cache->flush)
-		return;
+		return true;
 
 	for (i = 0; i < cache->c_hashsize; i++) {
 		hash = &cache->c_hash[i];
@@ -650,11 +651,13 @@ cache_flush(
 		pthread_mutex_lock(&hash->ch_mutex);
 		list_for_each_entry(node, &hash->ch_list, cn_hash) {
 			pthread_mutex_lock(&node->cn_mutex);
-			cache->flush(cache, node);
+			still_dirty |= cache->flush(cache, node);
 			pthread_mutex_unlock(&node->cn_mutex);
 		}
 		pthread_mutex_unlock(&hash->ch_mutex);
 	}
+
+	return !still_dirty;
 }
 
 #define	HASH_REPORT	(3 * HASH_CACHE_RATIO)

[PATCH 15/21] cache: add a "get only if incore" flag to cache_node_get

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add a new flag to cache_node_get so that callers can specify that they
only want the cache to return an existing cache node, and not create a
new one.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |    5 ++++-
 lib/support/cache.c |    7 +++++++
 2 files changed, 11 insertions(+), 1 deletion(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index 8d39ca5c02a285..98b2182d49a6e0 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -134,7 +134,10 @@ void cache_walk(struct cache *cache, cache_walk_t fn, void *data);
 void cache_purge(struct cache *);
 bool cache_flush(struct cache *cache);
 
-int cache_node_get(struct cache *, cache_key_t, struct cache_node **);
+/* don't allocate a new node */
+#define CACHE_GET_INCORE	(1U << 0)
+int cache_node_get(struct cache *c, cache_key_t key, unsigned int cgflags,
+		   struct cache_node **nodep);
 void cache_node_put(struct cache *, struct cache_node *);
 void cache_node_set_priority(struct cache *, struct cache_node *, int);
 int cache_node_get_priority(struct cache_node *);
diff --git a/lib/support/cache.c b/lib/support/cache.c
index fa07b4ad8222d2..9da6c59b3b6391 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -403,6 +403,7 @@ int
 cache_node_get(
 	struct cache		*cache,
 	cache_key_t		key,
+	unsigned int		cgflags,
 	struct cache_node	**nodep)
 {
 	struct cache_hash	*hash;
@@ -456,6 +457,12 @@ cache_node_get(
 			continue;	/* what the hell, gcc? */
 		}
 		pthread_mutex_unlock(&hash->ch_mutex);
+
+		if (cgflags & CACHE_GET_INCORE) {
+			*nodep = NULL;
+			return 0;
+		}
+
 		/*
 		 * not found, allocate a new entry
 		 */

[PATCH 16/21] cache: support gradual expansion

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

It's probably not a good idea to expand the cache size by powers of two
beyond some random limit, so let the users figure that out if they want
to.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |   10 ++++++++++
 lib/support/cache.c |   12 ++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index 98b2182d49a6e0..ae37945c545f46 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -66,6 +66,14 @@ typedef int (*cache_node_compare_t)(struct cache_node *, cache_key_t);
 typedef unsigned int (*cache_bulk_relse_t)(struct cache *, struct list_head *);
 typedef int (*cache_node_get_t)(struct cache *c, struct cache_node *cn);
 typedef void (*cache_node_put_t)(struct cache *c, struct cache_node *cn);
+typedef unsigned int (*cache_node_resize_t)(const struct cache *c,
+					    unsigned int curr_size);
+
+static inline unsigned int cache_gradual_resize(const struct cache *cache,
+						unsigned int curr_size)
+{
+	return curr_size * 5 / 4;
+}
 
 struct cache_operations {
 	cache_node_hash_t	hash;
@@ -76,6 +84,7 @@ struct cache_operations {
 	cache_bulk_relse_t	bulkrelse;	/* optional */
 	cache_node_get_t	get;		/* optional */
 	cache_node_put_t	put;		/* optional */
+	cache_node_resize_t	resize;		/* optional */
 };
 
 struct cache_hash {
@@ -113,6 +122,7 @@ struct cache {
 	cache_bulk_relse_t	bulkrelse;	/* bulk release routine */
 	cache_node_get_t	get;		/* prepare cache node after get */
 	cache_node_put_t	put;		/* prepare to put cache node */
+	cache_node_resize_t	resize;		/* compute new maxcount */
 	unsigned int		c_hashsize;	/* hash bucket count */
 	unsigned int		c_hashshift;	/* hash key shift */
 	struct cache_hash	*c_hash;	/* hash table buckets */
diff --git a/lib/support/cache.c b/lib/support/cache.c
index 9da6c59b3b6391..dbaddc1bd36d3d 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -62,6 +62,7 @@ cache_init(
 		cache_operations->bulkrelse : cache_generic_bulkrelse;
 	cache->get = cache_operations->get;
 	cache->put = cache_operations->put;
+	cache->resize = cache_operations->resize;
 	pthread_mutex_init(&cache->c_mutex, NULL);
 
 	for (i = 0; i <= CACHE_DIRTY_PRIORITY; i++) {
@@ -90,11 +91,18 @@ static void
 cache_expand(
 	struct cache *		cache)
 {
+	unsigned int		new_size = 0;
+
 	pthread_mutex_lock(&cache->c_mutex);
+	if (cache->resize)
+		new_size = cache->resize(cache, cache->c_maxcount);
+	if (new_size <= cache->c_maxcount)
+		new_size = cache->c_maxcount * 2;
 #ifdef CACHE_DEBUG
-	fprintf(stderr, "doubling cache size to %d\n", 2 * cache->c_maxcount);
+	fprintf(stderr, "increasing cache max size from %u to %u\n",
+			cache->c_maxcount, new_size);
 #endif
-	cache->c_maxcount *= 2;
+	cache->c_maxcount = new_size;
 	pthread_mutex_unlock(&cache->c_mutex);
 }
 

[PATCH 17/21] cache: implement automatic shrinking

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Shrink the cache whenever maxcount has been expanded beyond its initial
value, we release a cached object to one of the mru lists and the number
of objects sitting on the mru is enough to drop the cache count down a
level.  This enables a cache to reduce its memory consumption after a
spike in which reclamation wasn't possible.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |   17 ++++++-
 lib/support/cache.c |  118 ++++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 126 insertions(+), 9 deletions(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index ae37945c545f46..cd738b6cd3a460 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -16,6 +16,9 @@
  */
 #define CACHE_MISCOMPARE_PURGE	(1 << 0)
 
+/* Automatically shrink the cache's max_count when possible. */
+#define CACHE_CAN_SHRINK	(1U << 1)
+
 /*
  * cache object campare return values
  */
@@ -67,12 +70,18 @@ typedef unsigned int (*cache_bulk_relse_t)(struct cache *, struct list_head *);
 typedef int (*cache_node_get_t)(struct cache *c, struct cache_node *cn);
 typedef void (*cache_node_put_t)(struct cache *c, struct cache_node *cn);
 typedef unsigned int (*cache_node_resize_t)(const struct cache *c,
-					    unsigned int curr_size);
+					    unsigned int curr_size,
+					    int dir);
 
 static inline unsigned int cache_gradual_resize(const struct cache *cache,
-						unsigned int curr_size)
+						unsigned int curr_size,
+						int dir)
 {
-	return curr_size * 5 / 4;
+	if (dir < 0)
+		return curr_size * 9 / 10;
+	else if (dir > 0)
+		return curr_size * 5 / 4;
+	return curr_size;
 }
 
 struct cache_operations {
@@ -111,6 +120,7 @@ struct cache_node {
 
 struct cache {
 	int			c_flags;	/* behavioural flags */
+	unsigned int		c_orig_max;	/* original max cache nodes */
 	unsigned int		c_maxcount;	/* max cache nodes */
 	unsigned int		c_count;	/* count of nodes */
 	pthread_mutex_t		c_mutex;	/* node count mutex */
@@ -143,6 +153,7 @@ void cache_destroy(struct cache *cache);
 void cache_walk(struct cache *cache, cache_walk_t fn, void *data);
 void cache_purge(struct cache *);
 bool cache_flush(struct cache *cache);
+void cache_shrink(struct cache *cache);
 
 /* don't allocate a new node */
 #define CACHE_GET_INCORE	(1U << 0)
diff --git a/lib/support/cache.c b/lib/support/cache.c
index dbaddc1bd36d3d..7e1ddc3cc8788d 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -53,6 +53,7 @@ cache_init(
 	cache->c_hits = 0;
 	cache->c_misses = 0;
 	cache->c_maxcount = maxcount;
+	cache->c_orig_max = maxcount;
 	cache->hash = cache_operations->hash;
 	cache->alloc = cache_operations->alloc;
 	cache->flush = cache_operations->flush;
@@ -95,7 +96,7 @@ cache_expand(
 
 	pthread_mutex_lock(&cache->c_mutex);
 	if (cache->resize)
-		new_size = cache->resize(cache, cache->c_maxcount);
+		new_size = cache->resize(cache, cache->c_maxcount, 1);
 	if (new_size <= cache->c_maxcount)
 		new_size = cache->c_maxcount * 2;
 #ifdef CACHE_DEBUG
@@ -226,7 +227,8 @@ static unsigned int
 cache_shake(
 	struct cache *		cache,
 	unsigned int		priority,
-	bool			purge)
+	bool			purge,
+	unsigned int		nr_to_shake)
 {
 	struct cache_mru	*mru;
 	struct cache_hash	*hash;
@@ -274,7 +276,7 @@ cache_shake(
 		pthread_mutex_unlock(&node->cn_mutex);
 
 		count++;
-		if (!purge && count == CACHE_SHAKE_COUNT)
+		if (!purge && count == nr_to_shake)
 			break;
 	}
 	pthread_mutex_unlock(&mru->cm_mutex);
@@ -287,7 +289,7 @@ cache_shake(
 		pthread_mutex_unlock(&cache->c_mutex);
 	}
 
-	return (count == CACHE_SHAKE_COUNT) ? priority : ++priority;
+	return (count == nr_to_shake) ? priority : ++priority;
 }
 
 /*
@@ -477,7 +479,7 @@ cache_node_get(
 		node = cache_node_allocate(cache, key);
 		if (node)
 			break;
-		priority = cache_shake(cache, priority, false);
+		priority = cache_shake(cache, priority, false, CACHE_SHAKE_COUNT);
 		/*
 		 * We start at 0; if we free CACHE_SHAKE_COUNT we get
 		 * back the same priority, if not we get back priority+1.
@@ -507,12 +509,112 @@ cache_node_get(
 	return 1;
 }
 
+static unsigned int cache_mru_count(const struct cache *cache)
+{
+	const struct cache_mru	*mru = cache->c_mrus;
+	unsigned int		mru_count = 0;
+	unsigned int		i;
+
+	for (i = 0; i < CACHE_NR_PRIORITIES; i++, mru++)
+		mru_count += mru->cm_count;
+
+	return mru_count;
+}
+
+
+void cache_shrink(struct cache *cache)
+{
+	unsigned int		mru_count = 0;
+	unsigned int		threshold = 0;
+	unsigned int		priority = 0;
+	unsigned int		new_size;
+
+	pthread_mutex_lock(&cache->c_mutex);
+	/* Don't shrink below the original cache size */
+	if (cache->c_maxcount <= cache->c_orig_max)
+		goto out_unlock;
+
+	mru_count = cache_mru_count(cache);
+
+	/*
+	 * If there's not even a batch of nodes on the MRU to try to free,
+	 * don't bother with the rest.
+	 */
+	if (mru_count < CACHE_SHAKE_COUNT)
+		goto out_unlock;
+
+	/*
+	 * Figure out the next step down in size, but don't go below the
+	 * original size.
+	 */
+	if (cache->resize)
+		new_size = cache->resize(cache, cache->c_maxcount, -1);
+	else
+		new_size = cache->c_maxcount / 2;
+	if (new_size >= cache->c_maxcount)
+		goto out_unlock;
+	if (new_size < cache->c_orig_max)
+		new_size = cache->c_orig_max;
+
+	/*
+	 * If we can't purge enough nodes to get the node count below new_size,
+	 * don't resize the cache.
+	 */
+	if (cache->c_count - mru_count >= new_size)
+		goto out_unlock;
+
+#ifdef CACHE_DEBUG
+	fprintf(stderr, "decreasing cache max size from %u to %u (currently %u)\n",
+		cache->c_maxcount, new_size, cache->c_count);
+#endif
+	cache->c_maxcount = new_size;
+
+	/* Try to reduce the number of cached objects. */
+	do {
+		unsigned int new_priority;
+
+		/*
+		 * The threshold is the amount we need to purge to get c_count
+		 * below the new maxcount.  Try to free some objects off the
+		 * MRU.  Drop c_mutex because cache_shake will take it.
+		 */
+		threshold = cache->c_count - new_size;
+		pthread_mutex_unlock(&cache->c_mutex);
+
+		new_priority = cache_shake(cache, priority, false, threshold);
+
+		/* Either we made no progress or we ran out of MRU levels */
+		if (new_priority == priority ||
+		    new_priority > CACHE_MAX_PRIORITY)
+			return;
+		priority = new_priority;
+
+		pthread_mutex_lock(&cache->c_mutex);
+		/*
+		 * Someone could have walked in and changed the cache maxsize
+		 * again while we had the lock dropped.  If that happened, stop
+		 * clearing.
+		 */
+		if (cache->c_maxcount != new_size)
+			goto out_unlock;
+
+		mru_count = cache_mru_count(cache);
+		if (cache->c_count - mru_count >= new_size)
+			goto out_unlock;
+	} while (1);
+
+out_unlock:
+	pthread_mutex_unlock(&cache->c_mutex);
+	return;
+}
+
 void
 cache_node_put(
 	struct cache *		cache,
 	struct cache_node *	node)
 {
 	struct cache_mru *	mru;
+	bool was_put = false;
 
 	pthread_mutex_lock(&node->cn_mutex);
 #ifdef CACHE_DEBUG
@@ -528,6 +630,7 @@ cache_node_put(
 	}
 #endif
 	node->cn_count--;
+	was_put = (node->cn_count == 0);
 
 	if (node->cn_count == 0 && cache->put)
 		cache->put(cache, node);
@@ -541,6 +644,9 @@ cache_node_put(
 	}
 
 	pthread_mutex_unlock(&node->cn_mutex);
+
+	if (was_put && (cache->c_flags & CACHE_CAN_SHRINK))
+		cache_shrink(cache);
 }
 
 void
@@ -632,7 +738,7 @@ cache_purge(
 	int			i;
 
 	for (i = 0; i <= CACHE_DIRTY_PRIORITY; i++)
-		cache_shake(cache, i, true);
+		cache_shake(cache, i, true, CACHE_SHAKE_COUNT);
 
 #ifdef CACHE_DEBUG
 	if (cache->c_count != 0) {

[PATCH 18/21] fuse4fs: add cache to track open files

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add our own inode cache so that we can track open files.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h |    7 +++
 fuse4fs/Makefile.in |    3 +
 fuse4fs/fuse4fs.c   |  132 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 141 insertions(+), 1 deletion(-)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index cd738b6cd3a460..f482948a3b6331 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -6,6 +6,13 @@
 #ifndef __CACHE_H__
 #define __CACHE_H__
 
+/*  2^63 + 2^61 - 2^57 + 2^54 - 2^51 - 2^18 + 1 */
+#define GOLDEN_RATIO_PRIME	0x9e37fffffffc0001UL
+#ifndef CACHE_LINE_SIZE
+/* if the system didn't tell us, guess something reasonable */
+#define CACHE_LINE_SIZE		64
+#endif
+
 /*
  * initialisation flags
  */
diff --git a/fuse4fs/Makefile.in b/fuse4fs/Makefile.in
index 6b41d1dd5ffe8d..9f3547c271638f 100644
--- a/fuse4fs/Makefile.in
+++ b/fuse4fs/Makefile.in
@@ -146,7 +146,8 @@ fuse4fs.o: $(srcdir)/fuse4fs.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/ext2fsP.h \
  $(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/version.h \
- $(top_srcdir)/lib/e2p/e2p.h
+ $(top_srcdir)/lib/e2p/e2p.h $(top_srcdir)/lib/support/cache.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/support/xbitops.h
 journal.o: $(srcdir)/../debugfs/journal.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/../debugfs/journal.h \
  $(top_srcdir)/e2fsck/jfs_user.h $(top_srcdir)/e2fsck/e2fsck.h \
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 8b65dd1b419eaa..5b06e5a5b9668e 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -27,6 +27,7 @@
 #include <unistd.h>
 #include <ctype.h>
 #include <stdbool.h>
+#include <assert.h>
 #define FUSE_DARWIN_ENABLE_EXTENSIONS 0
 #ifdef __SET_FOB_FOR_FUSE
 # error Do not set magic value __SET_FOB_FOR_FUSE!!!!
@@ -49,6 +50,8 @@
 #include "ext2fs/ext2fs.h"
 #include "ext2fs/ext2_fs.h"
 #include "ext2fs/ext2fsP.h"
+#include "support/list.h"
+#include "support/cache.h"
 
 #include "../version.h"
 #include "uuid/uuid.h"
@@ -205,6 +208,7 @@ int journal_enable_debug = -1;
 #define FUSE4FS_FILE_MAGIC	(0xEF53DEAFUL)
 struct fuse4fs_file_handle {
 	unsigned long magic;
+	struct fuse4fs_inode *fi;
 	ext2_ino_t ino;
 	int open_flags;
 	int check_flags;
@@ -257,6 +261,7 @@ struct fuse4fs {
 	int timing;
 #endif
 	struct fuse_session *fuse;
+	struct cache inodes;
 };
 
 #define FUSE4FS_CHECK_HANDLE(req, fh) \
@@ -351,6 +356,115 @@ static inline int u_log2(unsigned int arg)
 	return l;
 }
 
+struct fuse4fs_inode {
+	struct cache_node	i_cnode;
+	ext2_ino_t		i_ino;
+	unsigned int		i_open_count;
+};
+
+struct fuse4fs_ikey {
+	ext2_ino_t		i_ino;
+};
+
+#define ICKEY(key)	((struct fuse4fs_ikey *)(key))
+#define ICNODE(node)	(container_of((node), struct fuse4fs_inode, i_cnode))
+
+static unsigned int
+icache_hash(cache_key_t key, unsigned int hashsize, unsigned int hashshift)
+{
+	uint64_t	hashval = ICKEY(key)->i_ino;
+	uint64_t	tmp;
+
+	tmp = hashval ^ (GOLDEN_RATIO_PRIME + hashval) / CACHE_LINE_SIZE;
+	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> hashshift);
+	return tmp % hashsize;
+}
+
+static int icache_compare(struct cache_node *node, cache_key_t key)
+{
+	struct fuse4fs_inode *fi = ICNODE(node);
+	struct fuse4fs_ikey *ikey = ICKEY(key);
+
+	if (fi->i_ino == ikey->i_ino)
+		return CACHE_HIT;
+
+	return CACHE_MISS;
+}
+
+static struct cache_node *icache_alloc(struct cache *c, cache_key_t key)
+{
+	struct fuse4fs_ikey *ikey = ICKEY(key);
+	struct fuse4fs_inode *fi;
+
+	fi = calloc(1, sizeof(struct fuse4fs_inode));
+	if (!fi)
+		return NULL;
+
+	fi->i_ino = ikey->i_ino;
+	return &fi->i_cnode;
+}
+
+static bool icache_flush(struct cache *c, struct cache_node *node)
+{
+	return false;
+}
+
+static void icache_relse(struct cache *c, struct cache_node *node)
+{
+	struct fuse4fs_inode *fi = ICNODE(node);
+
+	assert(fi->i_open_count == 0);
+	free(fi);
+}
+
+static unsigned int icache_bulkrelse(struct cache *cache,
+				     struct list_head *list)
+{
+	struct cache_node *cn, *n;
+	int count = 0;
+
+	if (list_empty(list))
+		return 0;
+
+	list_for_each_entry_safe(cn, n, list, cn_mru) {
+		icache_relse(cache, cn);
+		count++;
+	}
+
+	return count;
+}
+
+static const struct cache_operations icache_ops = {
+	.hash		= icache_hash,
+	.alloc		= icache_alloc,
+	.flush		= icache_flush,
+	.relse		= icache_relse,
+	.compare	= icache_compare,
+	.bulkrelse	= icache_bulkrelse,
+	.resize		= cache_gradual_resize,
+};
+
+static errcode_t fuse4fs_iget(struct fuse4fs *ff, ext2_ino_t ino,
+			      struct fuse4fs_inode **fip)
+{
+	struct fuse4fs_ikey ikey = {
+		.i_ino = ino,
+	};
+	struct cache_node *node = NULL;
+
+	cache_node_get(&ff->inodes, &ikey, 0, &node);
+	if (!node)
+		return ENOMEM;
+
+	*fip = ICNODE(node);
+	return 0;
+}
+
+static void fuse4fs_iput(struct fuse4fs *ff, struct fuse4fs_inode *fi)
+{
+	cache_node_put(&ff->inodes, &fi->i_cnode);
+}
+
 static inline blk64_t FUSE4FS_B_TO_FSBT(const struct fuse4fs *ff, off_t pos)
 {
 	return pos >> ff->blocklog;
@@ -954,6 +1068,11 @@ static void fuse4fs_unmount(struct fuse4fs *ff)
 	if (!ff->fs)
 		return;
 
+	if (cache_initialized(&ff->inodes)) {
+		cache_purge(&ff->inodes);
+		cache_destroy(&ff->inodes);
+	}
+
 	err = ext2fs_close(ff->fs);
 	if (err) {
 		err_printf(ff, "%s: %s\n", _("while closing fs"),
@@ -1002,6 +1121,10 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
 		return err;
 	}
 
+	err = cache_init(CACHE_CAN_SHRINK, 1U << 10, &icache_ops, &ff->inodes);
+	if (err)
+		return translate_error(ff->fs, 0, err);
+
 	ff->fs->priv_data = ff;
 	ff->blocklog = u_log2(ff->fs->blocksize);
 	ff->blockmask = ff->fs->blocksize - 1;
@@ -2071,6 +2194,7 @@ static int fuse4fs_remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 	if (inode.i_links_count)
 		goto write_out;
 
+
 	if (ext2fs_has_feature_ea_inode(fs->super)) {
 		ret = fuse4fs_remove_ea_inodes(ff, ino, &inode);
 		if (ret)
@@ -2987,6 +3111,13 @@ static int fuse4fs_open_file(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 			goto out;
 	}
 
+	err = fuse4fs_iget(ff, file->ino, &file->fi);
+	if (err) {
+		ret = translate_error(fs, 0, err);
+		goto out;
+	}
+	file->fi->i_open_count++;
+
 	file->check_flags = check;
 	fuse4fs_set_handle(fp, file);
 
@@ -3175,6 +3306,7 @@ static void op_release(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 			ret = translate_error(fs, fh->ino, err);
 	}
 
+	fuse4fs_iput(ff, fh->fi);
 	fp->fh = 0;
 	fuse4fs_finish(ff, ret);
 

[PATCH 19/21] fuse4fs: use the orphaned inode list

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Put open but unlinked files on the orphan list, and remove them when the
last open fd releases the inode.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |  181 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 178 insertions(+), 3 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 5b06e5a5b9668e..e046c782957e60 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -960,6 +960,13 @@ static int fuse4fs_inum_access(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 		   inode_uid(inode), inode_gid(inode),
 		   ctxt->uid, ctxt->gid);
 
+	/* linked files cannot be on the unlinked list or deleted */
+	if (inode.i_dtime != 0) {
+		dbg_printf(ff, "%s: unlinked ino=%d dtime=0x%x\n",
+			   __func__, ino, inode.i_dtime);
+		return -ENOENT;
+	}
+
 	/* existence check */
 	if (mask == 0)
 		return 0;
@@ -2162,9 +2169,80 @@ static int fuse4fs_remove_ea_inodes(struct fuse4fs *ff, ext2_ino_t ino,
 	return 0;
 }
 
+static int fuse4fs_add_to_orphans(struct fuse4fs *ff, ext2_ino_t ino,
+				  struct ext2_inode_large *inode)
+{
+	ext2_filsys fs = ff->fs;
+
+	dbg_printf(ff, "%s: orphan ino=%d dtime=%d next=%d\n",
+		   __func__, ino, inode->i_dtime, fs->super->s_last_orphan);
+
+	inode->i_dtime = fs->super->s_last_orphan;
+	fs->super->s_last_orphan = ino;
+	ext2fs_mark_super_dirty(fs);
+
+	return 0;
+}
+
+static int fuse4fs_remove_from_orphans(struct fuse4fs *ff, ext2_ino_t ino,
+				       struct ext2_inode_large *inode)
+{
+	ext2_filsys fs = ff->fs;
+	ext2_ino_t prev_orphan;
+	errcode_t err;
+
+	dbg_printf(ff, "%s: super=%d ino=%d next=%d\n",
+		   __func__, fs->super->s_last_orphan, ino, inode->i_dtime);
+
+	/* If we're lucky, the ondisk superblock points to us */
+	if (fs->super->s_last_orphan == ino) {
+		dbg_printf(ff, "%s: superblock\n", __func__);
+
+		fs->super->s_last_orphan = inode->i_dtime;
+		inode->i_dtime = 0;
+		ext2fs_mark_super_dirty(fs);
+		return 0;
+	}
+
+	/* Otherwise walk the ondisk orphan list. */
+	prev_orphan = fs->super->s_last_orphan;
+	while (prev_orphan != 0) {
+		struct ext2_inode_large orphan;
+
+		err = fuse4fs_read_inode(fs, prev_orphan, &orphan);
+		if (err)
+			return translate_error(fs, prev_orphan, err);
+
+		if (orphan.i_dtime == prev_orphan)
+			return translate_error(fs, prev_orphan,
+					       EXT2_ET_FILESYSTEM_CORRUPTED);
+
+		if (orphan.i_dtime == ino) {
+			dbg_printf(ff, "%s: prev=%d\n",
+				   __func__, prev_orphan);
+
+			orphan.i_dtime = inode->i_dtime;
+			inode->i_dtime = 0;
+
+			err = fuse4fs_write_inode(fs, prev_orphan, &orphan);
+			if (err)
+				return translate_error(fs, prev_orphan, err);
+
+			return 0;
+		}
+
+		dbg_printf(ff, "%s: orphan=%d next=%d\n",
+			   __func__, prev_orphan, orphan.i_dtime);
+		prev_orphan = orphan.i_dtime;
+	}
+
+	return translate_error(fs, ino, EXT2_ET_FILESYSTEM_CORRUPTED);
+}
+
 static int fuse4fs_remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 {
 	ext2_filsys fs = ff->fs;
+	struct fuse4fs_inode *fi;
 	errcode_t err;
 	struct ext2_inode_large inode;
 	int ret = 0;
@@ -2181,7 +2259,6 @@ static int fuse4fs_remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 		return 0; /* XXX: already done? */
 	case 1:
 		inode.i_links_count--;
-		ext2fs_set_dtime(fs, EXT2_INODE(&inode));
 		break;
 	default:
 		inode.i_links_count--;
@@ -2194,6 +2271,26 @@ static int fuse4fs_remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 	if (inode.i_links_count)
 		goto write_out;
 
+	err = fuse4fs_iget(ff, ino, &fi);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	dbg_printf(ff, "%s: put ino=%d opencount=%d\n", __func__, ino,
+		   fi->i_open_count);
+
+	/*
+	 * The file is unlinked but still open; add it to the orphan list and
+	 * free it later.
+	 */
+	if (fi->i_open_count > 0) {
+		fuse4fs_iput(ff, fi);
+		ret = fuse4fs_add_to_orphans(ff, ino, &inode);
+		if (ret)
+			return ret;
+
+		goto write_out;
+	}
+	fuse4fs_iput(ff, fi);
 
 	if (ext2fs_has_feature_ea_inode(fs->super)) {
 		ret = fuse4fs_remove_ea_inodes(ff, ino, &inode);
@@ -2213,6 +2310,7 @@ static int fuse4fs_remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 			return translate_error(fs, ino, err);
 	}
 
+	ext2fs_set_dtime(fs, EXT2_INODE(&inode));
 	ext2fs_inode_alloc_stats2(fs, ino, -1,
 				  LINUX_S_ISDIR(inode.i_mode));
 
@@ -2761,6 +2859,16 @@ static void op_link(fuse_req_t req, fuse_ino_t child_fino,
 	if (ret)
 		goto out2;
 
+	/*
+	 * Linking a file back into the filesystem requires removing it from
+	 * the orphan list.
+	 */
+	if (inode.i_links_count == 0) {
+		ret = fuse4fs_remove_from_orphans(ff, child, &inode);
+		if (ret)
+			goto out2;
+	}
+
 	inode.i_links_count++;
 	ret = update_ctime(fs, child, &inode);
 	if (ret)
@@ -3044,7 +3152,8 @@ static void detect_linux_executable_open(int kernel_flags, int *access_check,
 #endif /* __linux__ */
 
 static int fuse4fs_open_file(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
-			     ext2_ino_t ino, struct fuse_file_info *fp)
+			     ext2_ino_t ino,
+			     struct fuse_file_info *fp)
 {
 	ext2_filsys fs = ff->fs;
 	errcode_t err;
@@ -3120,6 +3229,8 @@ static int fuse4fs_open_file(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 
 	file->check_flags = check;
 	fuse4fs_set_handle(fp, file);
+	dbg_printf(ff, "%s: ino=%d fh=%p opencount=%d\n", __func__, ino, file,
+		   file->fi->i_open_count);
 
 out:
 	if (ret)
@@ -3136,6 +3247,8 @@ static void op_open(fuse_req_t req, fuse_ino_t fino, struct fuse_file_info *fp)
 
 	FUSE4FS_CHECK_CONTEXT(req);
 	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+	dbg_printf(ff, "%s: ino=%d\n", __func__, ino);
+
 	fuse4fs_start(ff);
 	ret = fuse4fs_open_file(ff, ctxt, ino, fp);
 	fuse4fs_finish(ff, ret);
@@ -3284,6 +3397,55 @@ static void op_write(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 		fuse_reply_err(req, -ret);
 }
 
+static int fuse4fs_free_unlinked(struct fuse4fs *ff, ext2_ino_t ino)
+{
+	struct ext2_inode_large inode;
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
+	int ret = 0;
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	if (inode.i_links_count > 0)
+		return 0;
+
+	dbg_printf(ff, "%s: ino=%d links=%d\n", __func__, ino,
+		   inode.i_links_count);
+
+	if (ext2fs_has_feature_ea_inode(fs->super)) {
+		ret = fuse4fs_remove_ea_inodes(ff, ino, &inode);
+		if (ret)
+			return ret;
+	}
+
+	/* Nobody holds this file; free its blocks! */
+	err = ext2fs_free_ext_attr(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	if (ext2fs_inode_has_valid_blocks2(fs, EXT2_INODE(&inode))) {
+		err = ext2fs_punch(fs, ino, EXT2_INODE(&inode), NULL,
+				   0, ~0ULL);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	ret = fuse4fs_remove_from_orphans(ff, ino, &inode);
+	if (ret)
+		return ret;
+
+	ext2fs_set_dtime(fs, EXT2_INODE(&inode));
+	ext2fs_inode_alloc_stats2(fs, ino, -1, LINUX_S_ISDIR(inode.i_mode));
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
 static void op_release(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 		       struct fuse_file_info *fp)
 {
@@ -3295,9 +3457,21 @@ static void op_release(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 
 	FUSE4FS_CHECK_CONTEXT(req);
 	FUSE4FS_CHECK_HANDLE(req, fh);
-	dbg_printf(ff, "%s: ino=%d\n", __func__, fh->ino);
+	dbg_printf(ff, "%s: ino=%d fh=%p opencount=%u\n",
+		   __func__, fh->ino, fh, fh->fi->i_open_count);
+
 	fs = fuse4fs_start(ff);
 
+	/*
+	 * If the file is no longer open and is unlinked, free it, which
+	 * removes it from the ondisk list.
+	 */
+	if (--fh->fi->i_open_count == 0) {
+		ret = fuse4fs_free_unlinked(ff, fh->ino);
+		if (ret)
+			goto out_iput;
+	}
+
 	if ((fp->flags & O_SYNC) &&
 	    fuse4fs_is_writeable(ff) &&
 	    (fh->open_flags & EXT2_FILE_WRITE)) {
@@ -3306,6 +3480,7 @@ static void op_release(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 			ret = translate_error(fs, fh->ino, err);
 	}
 
+out_iput:
 	fuse4fs_iput(ff, fh->fi);
 	fp->fh = 0;
 	fuse4fs_finish(ff, ret);

[PATCH 20/21] fuse4fs: implement FUSE_TMPFILE

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Allow creation of O_TMPFILE files now that we know how to use the
unlinked list.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   93 ++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 67 insertions(+), 26 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index e046c782957e60..1015b13f4adac7 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -902,22 +902,25 @@ static inline int fuse4fs_want_check_owner(struct fuse4fs *ff,
 
 /* Test for append permission */
 #define A_OK	16
+/* Test for linked file */
+#define L_OK	32
 
 static int fuse4fs_iflags_access(struct fuse4fs *ff, ext2_ino_t ino,
 				 const struct ext2_inode *inode, int mask)
 {
-	EXT2FS_BUILD_BUG_ON((A_OK & (R_OK | W_OK | X_OK | F_OK)) != 0);
+	EXT2FS_BUILD_BUG_ON(((A_OK | L_OK) & (R_OK | W_OK | X_OK | F_OK)) != 0);
 
 	/* no writing or metadata changes to read-only or broken fs */
 	if ((mask & (W_OK | A_OK)) && !fuse4fs_is_writeable(ff))
 		return -EROFS;
 
-	dbg_printf(ff, "access ino=%d mask=e%s%s%s%s iflags=0x%x\n",
+	dbg_printf(ff, "access ino=%d mask=e%s%s%s%s%s iflags=0x%x\n",
 		   ino,
 		   (mask & R_OK ? "r" : ""),
 		   (mask & W_OK ? "w" : ""),
 		   (mask & X_OK ? "x" : ""),
 		   (mask & A_OK ? "a" : ""),
+		   (mask & L_OK ? "l" : ""),
 		   inode->i_flags);
 
 	/* is immutable? */
@@ -950,21 +953,31 @@ static int fuse4fs_inum_access(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 		return translate_error(fs, ino, err);
 	perms = inode.i_mode & 0777;
 
-	dbg_printf(ff, "access ino=%d mask=e%s%s%s%s perms=0%o iflags=0x%x "
+	dbg_printf(ff, "access ino=%d mask=e%s%s%s%s%s perms=0%o iflags=0x%x "
 		   "fuid=%d fgid=%d uid=%d gid=%d\n", ino,
 		   (mask & R_OK ? "r" : ""),
 		   (mask & W_OK ? "w" : ""),
 		   (mask & X_OK ? "x" : ""),
 		   (mask & A_OK ? "a" : ""),
+		   (mask & L_OK ? "l" : ""),
 		   perms, inode.i_flags,
 		   inode_uid(inode), inode_gid(inode),
 		   ctxt->uid, ctxt->gid);
 
-	/* linked files cannot be on the unlinked list or deleted */
-	if (inode.i_dtime != 0) {
-		dbg_printf(ff, "%s: unlinked ino=%d dtime=0x%x\n",
-			   __func__, ino, inode.i_dtime);
-		return -ENOENT;
+	if (mask & L_OK) {
+		/* linked files cannot be on the unlinked list or deleted */
+		if (inode.i_dtime != 0) {
+			dbg_printf(ff, "%s: unlinked ino=%d dtime=0x%x\n",
+				   __func__, ino, inode.i_dtime);
+			return -ENOENT;
+		}
+	} else {
+		/* unlinked files cannot be deleted */
+		if (inode.i_dtime >= fs->super->s_inodes_count) {
+			dbg_printf(ff, "%s: deleted ino=%d dtime=0x%x\n",
+				   __func__, ino, inode.i_dtime);
+			return -ENOENT;
+		}
 	}
 
 	/* existence check */
@@ -3152,7 +3165,7 @@ static void detect_linux_executable_open(int kernel_flags, int *access_check,
 #endif /* __linux__ */
 
 static int fuse4fs_open_file(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
-			     ext2_ino_t ino,
+			     ext2_ino_t ino, bool linked,
 			     struct fuse_file_info *fp)
 {
 	ext2_filsys fs = ff->fs;
@@ -3182,6 +3195,9 @@ static int fuse4fs_open_file(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 		break;
 	}
 
+	if (linked)
+		check |= L_OK;
+
 	/*
 	 * If the caller wants to truncate the file, we need to ask for full
 	 * write access even if the caller claims to be appending.
@@ -3250,7 +3266,7 @@ static void op_open(fuse_req_t req, fuse_ino_t fino, struct fuse_file_info *fp)
 	dbg_printf(ff, "%s: ino=%d\n", __func__, ino);
 
 	fuse4fs_start(ff);
-	ret = fuse4fs_open_file(ff, ctxt, ino, fp);
+	ret = fuse4fs_open_file(ff, ctxt, ino, true, fp);
 	fuse4fs_finish(ff, ret);
 
 	if (ret)
@@ -4159,22 +4175,28 @@ static void op_create(fuse_req_t req, fuse_ino_t fino, const char *name,
 		goto out2;
 	}
 
-	dbg_printf(ff, "%s: creating dir=%d name='%s' child=%d\n",
-		   __func__, parent, name, child);
-	err = ext2fs_link(fs, parent, name, child,
-			  filetype | EXT2FS_LINK_EXPAND);
-	if (err) {
-		ret = translate_error(fs, parent, err);
-		goto out2;
+	if (name) {
+		dbg_printf(ff, "%s: creating dir=%d name='%s' child=%d\n",
+			   __func__, parent, name, child);
+
+		err = ext2fs_link(fs, parent, name, child,
+				  filetype | EXT2FS_LINK_EXPAND);
+		if (err) {
+			ret = translate_error(fs, parent, err);
+			goto out2;
+		}
+
+		ret = update_mtime(fs, parent, NULL);
+		if (ret)
+			goto out2;
+	} else {
+		dbg_printf(ff, "%s: creating dir=%d tempfile=%d\n",
+			   __func__, parent, child);
 	}
 
-	ret = update_mtime(fs, parent, NULL);
-	if (ret)
-		goto out2;
-
 	memset(&inode, 0, sizeof(inode));
 	inode.i_mode = mode;
-	inode.i_links_count = 1;
+	inode.i_links_count = name ? 1 : 0;
 	fuse4fs_set_extra_isize(ff, child, &inode);
 	fuse4fs_set_uid(&inode, ctxt->uid);
 	fuse4fs_set_gid(&inode, gid);
@@ -4192,6 +4214,12 @@ static void op_create(fuse_req_t req, fuse_ino_t fino, const char *name,
 		ext2fs_extent_free(handle);
 	}
 
+	if (!name) {
+		ret = fuse4fs_add_to_orphans(ff, child, &inode);
+		if (ret)
+			goto out2;
+	}
+
 	err = ext2fs_write_new_inode(fs, child, EXT2_INODE(&inode));
 	if (err) {
 		ret = translate_error(fs, child, err);
@@ -4213,13 +4241,15 @@ static void op_create(fuse_req_t req, fuse_ino_t fino, const char *name,
 		goto out2;
 
 	fp->flags &= ~O_TRUNC;
-	ret = fuse4fs_open_file(ff, ctxt, child, fp);
+	ret = fuse4fs_open_file(ff, ctxt, child, name != NULL, fp);
 	if (ret)
 		goto out2;
 
-	ret = fuse4fs_dirsync_flush(ff, parent, NULL);
-	if (ret)
-		goto out2;
+	if (name) {
+		ret = fuse4fs_dirsync_flush(ff, parent, NULL);
+		if (ret)
+			goto out2;
+	}
 
 	ret = fuse4fs_stat_inode(ff, child, NULL, &fstat);
 	if (ret)
@@ -4234,6 +4264,14 @@ static void op_create(fuse_req_t req, fuse_ino_t fino, const char *name,
 		fuse_reply_create(req, &fstat.entry, fp);
 }
 
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 17)
+static void op_tmpfile(fuse_req_t req, fuse_ino_t fino, mode_t mode,
+		       struct fuse_file_info *fp)
+{
+	op_create(req, fino, NULL, mode, fp);
+}
+#endif
+
 enum fuse4fs_time_action {
 	TA_NOW,		/* set to current time */
 	TA_OMIT,	/* do not set timestamp */
@@ -5225,6 +5263,9 @@ static struct fuse_lowlevel_ops fs_ops = {
 	.fsyncdir = op_fsync,
 	.access = op_access,
 	.create = op_create,
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 17)
+	.tmpfile = op_tmpfile,
+#endif
 	.bmap = op_bmap,
 #ifdef SUPERFLUOUS
 	.lock = op_lock,

[PATCH 21/21] fuse4fs: create incore reverse orphan list

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Create an incore orphan list so that removing open unlinked inodes
doesn't take forever.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |  178 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 174 insertions(+), 4 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 1015b13f4adac7..9a6913f6eef16a 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -356,10 +356,20 @@ static inline int u_log2(unsigned int arg)
 	return l;
 }
 
+/* inode is not on unlinked list */
+#define FUSE4FS_NULL_INO	((ext2_ino_t)~0ULL)
+
 struct fuse4fs_inode {
 	struct cache_node	i_cnode;
 	ext2_ino_t		i_ino;
 	unsigned int		i_open_count;
+
+	/*
+	 * FUSE4FS_NULL_INO: inode is not on the orphan list
+	 * 0: inode is the first on the orphan list
+	 * otherwise: inode is in the middle of the list
+	 */
+	ext2_ino_t		i_prev_orphan;
 };
 
 struct fuse4fs_ikey {
@@ -401,12 +411,15 @@ static struct cache_node *icache_alloc(struct cache *c, cache_key_t key)
 		return NULL;
 
 	fi->i_ino = ikey->i_ino;
+	fi->i_prev_orphan = FUSE4FS_NULL_INO;
 	return &fi->i_cnode;
 }
 
 static bool icache_flush(struct cache *c, struct cache_node *node)
 {
-	return false;
+	struct fuse4fs_inode *fi = ICNODE(node);
+
+	return fi->i_prev_orphan != FUSE4FS_NULL_INO;
 }
 
 static void icache_relse(struct cache *c, struct cache_node *node)
@@ -2186,10 +2199,31 @@ static int fuse4fs_add_to_orphans(struct fuse4fs *ff, ext2_ino_t ino,
 				  struct ext2_inode_large *inode)
 {
 	ext2_filsys fs = ff->fs;
+	struct fuse4fs_inode *fi;
+	ext2_ino_t orphan_ino = fs->super->s_last_orphan;
+	errcode_t err;
 
 	dbg_printf(ff, "%s: orphan ino=%d dtime=%d next=%d\n",
 		   __func__, ino, inode->i_dtime, fs->super->s_last_orphan);
 
+	/* Make the first orphan on the list point back to us */
+	if (orphan_ino != 0) {
+		err = fuse4fs_iget(ff, orphan_ino, &fi);
+		if (err)
+			return translate_error(fs, orphan_ino, err);
+
+		fi->i_prev_orphan = ino;
+		fuse4fs_iput(ff, fi);
+	}
+
+	/* Add ourselves to the head of the orphan list */
+	err = fuse4fs_iget(ff, ino, &fi);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	fi->i_prev_orphan = 0;
+	fuse4fs_iput(ff, fi);
+
 	inode->i_dtime = fs->super->s_last_orphan;
 	fs->super->s_last_orphan = ino;
 	ext2fs_mark_super_dirty(fs);
@@ -2197,24 +2231,158 @@ static int fuse4fs_add_to_orphans(struct fuse4fs *ff, ext2_ino_t ino,
 	return 0;
 }
 
+/*
+ * Given the orphan list excerpt: prev_orphan -> ino -> next_orphan, set
+ * next_orphan's backpointer to ino's backpointer (prev_orphan), having removed
+ * ino from the orphan list.
+ */
+static int fuse2fs_update_next_orphan_backlink(struct fuse4fs *ff,
+					       ext2_ino_t prev_orphan,
+					       ext2_ino_t ino,
+					       ext2_ino_t next_orphan)
+{
+	struct fuse4fs_inode *fi;
+	errcode_t err;
+	int ret = 0;
+
+	err = fuse4fs_iget(ff, next_orphan, &fi);
+	if (err)
+		return translate_error(ff->fs, next_orphan, err);
+
+	dbg_printf(ff, "%s: ino=%d cached next=%d nextprev=%d prev=%d\n",
+		   __func__, ino, next_orphan, fi->i_prev_orphan,
+		   prev_orphan);
+
+	if (fi->i_prev_orphan != ino) {
+		ret = translate_error(ff->fs, next_orphan,
+				      EXT2_ET_FILESYSTEM_CORRUPTED);
+		goto out_iput;
+	}
+
+	fi->i_prev_orphan = prev_orphan;
+out_iput:
+	fuse4fs_iput(ff, fi);
+	return ret;
+}
+
+/*
+ * Remove ino from the orphan list the fast way.  Returns 1 for success, 0 if
+ * it didn't do anything, or a negative errno.
+ */
+static int fuse4fs_fast_remove_from_orphans(struct fuse4fs *ff, ext2_ino_t ino,
+					    struct ext2_inode_large *inode)
+{
+	struct ext2_inode_large orphan;
+	ext2_filsys fs = ff->fs;
+	struct fuse4fs_inode *fi;
+	ext2_ino_t prev_orphan;
+	ext2_ino_t next_orphan = 0;
+	errcode_t err;
+	int ret = 0;
+
+	err = fuse4fs_iget(ff, ino, &fi);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	prev_orphan = fi->i_prev_orphan;
+	switch (prev_orphan) {
+	case 0:
+		/* First inode in the list */
+		dbg_printf(ff, "%s: ino=%d cached superblock\n", __func__, ino);
+
+		fs->super->s_last_orphan = inode->i_dtime;
+		next_orphan = inode->i_dtime;
+		inode->i_dtime = 0;
+		ext2fs_mark_super_dirty(fs);
+		fi->i_prev_orphan = FUSE4FS_NULL_INO;
+		break;
+	case FUSE4FS_NULL_INO:
+		/* unknown */
+		dbg_printf(ff, "%s: ino=%d broken list??\n", __func__, ino);
+		ret = 0;
+		goto out_iput;
+	default:
+		/* We're in the middle of the list */
+		err = fuse4fs_read_inode(fs, prev_orphan, &orphan);
+		if (err) {
+			ret = translate_error(fs, prev_orphan, err);
+			goto out_iput;
+		}
+
+		dbg_printf(ff,
+ "%s: ino=%d cached prev=%d prevnext=%d next=%d\n",
+			   __func__, ino, prev_orphan, orphan.i_dtime,
+			   inode->i_dtime);
+
+		if (orphan.i_dtime != ino) {
+			ret = translate_error(fs, prev_orphan,
+					      EXT2_ET_FILESYSTEM_CORRUPTED);
+			goto out_iput;
+		}
+
+		fi->i_prev_orphan = FUSE4FS_NULL_INO;
+		orphan.i_dtime = inode->i_dtime;
+		next_orphan = inode->i_dtime;
+		inode->i_dtime = 0;
+
+		err = fuse4fs_write_inode(fs, prev_orphan, &orphan);
+		if (err) {
+			ret = translate_error(fs, prev_orphan, err);
+			goto out_iput;
+		}
+
+		break;
+	}
+
+	/*
+	 * Make the next orphaned inode point back to the our own previous list
+	 * entry
+	 */
+	if (next_orphan != 0) {
+		ret = fuse2fs_update_next_orphan_backlink(ff, prev_orphan, ino,
+							  next_orphan);
+		if (ret)
+			goto out_iput;
+	}
+	ret = 1;
+
+out_iput:
+	fuse4fs_iput(ff, fi);
+	return ret;
+}
+
 static int fuse4fs_remove_from_orphans(struct fuse4fs *ff, ext2_ino_t ino,
 				       struct ext2_inode_large *inode)
 {
 	ext2_filsys fs = ff->fs;
 	ext2_ino_t prev_orphan;
+	ext2_ino_t next_orphan;
 	errcode_t err;
+	int ret;
 
 	dbg_printf(ff, "%s: super=%d ino=%d next=%d\n",
 		   __func__, fs->super->s_last_orphan, ino, inode->i_dtime);
 
-	/* If we're lucky, the ondisk superblock points to us */
+	/*
+	 * Fast way: use the incore list, which doesn't include any orphans
+	 * that were already on the superblock when we mounted.
+	 */
+	ret = fuse4fs_fast_remove_from_orphans(ff, ino, inode);
+	if (ret < 0)
+		return ret;
+	if (ret == 1)
+		return 0;
+
+	/* Slow way: If we're lucky, the ondisk superblock points to us */
 	if (fs->super->s_last_orphan == ino) {
 		dbg_printf(ff, "%s: superblock\n", __func__);
 
+		next_orphan = inode->i_dtime;
 		fs->super->s_last_orphan = inode->i_dtime;
 		inode->i_dtime = 0;
 		ext2fs_mark_super_dirty(fs);
-		return 0;
+		return fuse2fs_update_next_orphan_backlink(ff, 0, ino,
+							   next_orphan);
 	}
 
 	/* Otherwise walk the ondisk orphan list. */
@@ -2234,6 +2402,7 @@ static int fuse4fs_remove_from_orphans(struct fuse4fs *ff, ext2_ino_t ino,
 			dbg_printf(ff, "%s: prev=%d\n",
 				   __func__, prev_orphan);
 
+			next_orphan = inode->i_dtime;
 			orphan.i_dtime = inode->i_dtime;
 			inode->i_dtime = 0;
 
@@ -2241,7 +2410,8 @@ static int fuse4fs_remove_from_orphans(struct fuse4fs *ff, ext2_ino_t ino,
 			if (err)
 				return translate_error(fs, prev_orphan, err);
 
-			return 0;
+			return fuse2fs_update_next_orphan_backlink(ff,
+					prev_orphan, ino, next_orphan);
 		}
 
 		dbg_printf(ff, "%s: orphan=%d next=%d\n",

[PATCH 01/10] libext2fs: make it possible to extract the fd from an IO manager

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Make it so that we can extract the fd from an open IO manager.  This
will be used in subsequent patches to register the open block device
with the fuse iomap kernel driver.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/ext2_io.h         |    4 +++-
 debian/libext2fs2t64.symbols |    1 +
 lib/ext2fs/io_manager.c      |    8 ++++++++
 lib/ext2fs/unix_io.c         |   15 +++++++++++++++
 4 files changed, 27 insertions(+), 1 deletion(-)


diff --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h
index 39a4e8fcf6b515..f53983b30996b4 100644
--- a/lib/ext2fs/ext2_io.h
+++ b/lib/ext2fs/ext2_io.h
@@ -102,7 +102,8 @@ struct struct_io_manager {
 				     unsigned long long count);
 	errcode_t (*zeroout)(io_channel channel, unsigned long long block,
 			     unsigned long long count);
-	long	reserved[14];
+	errcode_t (*get_fd)(io_channel channel, int *fd);
+	long	reserved[13];
 };
 
 #define IO_FLAG_RW		0x0001
@@ -145,6 +146,7 @@ extern errcode_t io_channel_alloc_buf(io_channel channel,
 extern errcode_t io_channel_cache_readahead(io_channel io,
 					    unsigned long long block,
 					    unsigned long long count);
+extern errcode_t io_channel_get_fd(io_channel io, int *fd);
 
 #ifdef _WIN32
 /* windows_io.c */
diff --git a/debian/libext2fs2t64.symbols b/debian/libext2fs2t64.symbols
index a3042c3292da93..8e3214ee31e337 100644
--- a/debian/libext2fs2t64.symbols
+++ b/debian/libext2fs2t64.symbols
@@ -693,6 +693,7 @@ libext2fs.so.2 libext2fs2t64 #MINVER#
  io_channel_alloc_buf@Base 1.42.3
  io_channel_cache_readahead@Base 1.43
  io_channel_discard@Base 1.42
+ io_channel_get_fd@Base 1.47.99
  io_channel_read_blk64@Base 1.41.1
  io_channel_set_options@Base 1.37
  io_channel_write_blk64@Base 1.41.1
diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
index dca6af09996b70..6b4dca5e4dbca2 100644
--- a/lib/ext2fs/io_manager.c
+++ b/lib/ext2fs/io_manager.c
@@ -150,3 +150,11 @@ errcode_t io_channel_cache_readahead(io_channel io, unsigned long long block,
 
 	return io->manager->cache_readahead(io, block, count);
 }
+
+errcode_t io_channel_get_fd(io_channel io, int *fd)
+{
+	if (!io->manager->get_fd)
+		return EXT2_ET_OP_NOT_SUPPORTED;
+
+	return io->manager->get_fd(io, fd);
+}
diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 723a5c2474cdd5..a540572a840d17 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -1662,6 +1662,19 @@ static errcode_t unix_zeroout(io_channel channel, unsigned long long block,
 unimplemented:
 	return EXT2_ET_UNIMPLEMENTED;
 }
+
+static errcode_t unix_get_fd(io_channel channel, int *fd)
+{
+	struct unix_private_data *data;
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	data = (struct unix_private_data *) channel->private_data;
+	EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+	*fd = data->dev;
+	return 0;
+}
+
 #if __GNUC_PREREQ (4, 6)
 #pragma GCC diagnostic pop
 #endif
@@ -1683,6 +1696,7 @@ static struct struct_io_manager struct_unix_manager = {
 	.discard	= unix_discard,
 	.cache_readahead	= unix_cache_readahead,
 	.zeroout	= unix_zeroout,
+	.get_fd		= unix_get_fd,
 };
 
 io_manager unix_io_manager = &struct_unix_manager;
@@ -1704,6 +1718,7 @@ static struct struct_io_manager struct_unixfd_manager = {
 	.discard	= unix_discard,
 	.cache_readahead	= unix_cache_readahead,
 	.zeroout	= unix_zeroout,
+	.get_fd		= unix_get_fd,
 };
 
 io_manager unixfd_io_manager = &struct_unixfd_manager;

[PATCH 02/10] libext2fs: always fsync the device when flushing the cache

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

When we're flushing the unix IO manager's buffer cache, we should always
fsync the block device, because something could have written to the
block device -- either the buffer cache itself, or a direct write.
Regardless, the callers all want all dirtied regions to be persisted to
stable media.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/unix_io.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)


diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index a540572a840d17..f716de35cf5cb1 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -1462,7 +1462,8 @@ static errcode_t unix_flush(io_channel channel)
 	retval = flush_cached_blocks(channel, data, 0);
 #endif
 #ifdef HAVE_FSYNC
-	if (!retval && fsync(data->dev) != 0)
+	/* always fsync the device, even if flushing our own cache failed */
+	if (fsync(data->dev) != 0 && !retval)
 		return errno;
 #endif
 	return retval;

[PATCH 03/10] libext2fs: always fsync the device when closing the unix IO manager

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

unix_close is the last chance that libext2fs has to report write
failures to users.  Although it's likely that ext2fs_close already
called ext2fs_flush and told the IO manager to flush, we could do one
more sync before we close the file descriptor.  Also don't override the
fsync's errno with the close's errno.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/unix_io.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)


diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index f716de35cf5cb1..b04e8a89a951dd 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -1146,8 +1146,11 @@ static errcode_t unix_close(io_channel channel)
 #ifndef NO_IO_CACHE
 	retval = flush_cached_blocks(channel, data, 0);
 #endif
+	/* always fsync the device, even if flushing our own cache failed */
+	if (fsync(data->dev) != 0 && !retval)
+		retval = errno;
 
-	if (close(data->dev) < 0)
+	if (close(data->dev) < 0 && !retval)
 		retval = errno;
 	free_cache(data);
 	free(data->cache);

[PATCH 04/10] libext2fs: only fsync the unix fd if we wrote to the device

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

As an optimization, only fsync the block device fd if we tried to write
to the io channel.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/unix_io.c |   48 ++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 42 insertions(+), 6 deletions(-)


diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index b04e8a89a951dd..b462c587e3e2ac 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -129,10 +129,13 @@ struct unix_cache {
 #define WRITE_DIRECT_SIZE 4	/* Must be smaller than CACHE_SIZE */
 #define READ_DIRECT_SIZE 4	/* Should be smaller than CACHE_SIZE */
 
+#define UNIX_STATE_DIRTY	(1U << 0) /* device needs fsyncing */
+
 struct unix_private_data {
 	int	magic;
 	int	dev;
 	int	flags;
+	unsigned int	state; /* UNIX_STATE_* */
 	int	align;
 	int	access_time;
 	ext2_loff_t offset;
@@ -1131,10 +1134,37 @@ static errcode_t unix_open(const char *name, int flags,
 	return unix_open_channel(name, fd, flags, channel, unix_io_manager);
 }
 
+static void mark_dirty(io_channel channel)
+{
+	struct unix_private_data *data =
+		(struct unix_private_data *) channel->private_data;
+
+	mutex_lock(data, CACHE_MTX);
+	data->state |= UNIX_STATE_DIRTY;
+	mutex_unlock(data, CACHE_MTX);
+}
+
+static errcode_t maybe_fsync(io_channel channel)
+{
+	struct unix_private_data *data =
+		(struct unix_private_data *) channel->private_data;
+	int was_dirty;
+
+	mutex_lock(data, CACHE_MTX);
+	was_dirty = data->state & UNIX_STATE_DIRTY;
+	data->state &= ~UNIX_STATE_DIRTY;
+	mutex_unlock(data, CACHE_MTX);
+
+	if (was_dirty && fsync(data->dev) != 0)
+		return errno;
+
+	return 0;
+}
+
 static errcode_t unix_close(io_channel channel)
 {
 	struct unix_private_data *data;
-	errcode_t	retval = 0;
+	errcode_t	retval = 0, retval2;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	data = (struct unix_private_data *) channel->private_data;
@@ -1147,8 +1177,9 @@ static errcode_t unix_close(io_channel channel)
 	retval = flush_cached_blocks(channel, data, 0);
 #endif
 	/* always fsync the device, even if flushing our own cache failed */
-	if (fsync(data->dev) != 0 && !retval)
-		retval = errno;
+	retval2 = maybe_fsync(channel);
+	if (retval2 && !retval)
+		retval = retval2;
 
 	if (close(data->dev) < 0 && !retval)
 		retval = errno;
@@ -1316,6 +1347,8 @@ static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
 	data = (struct unix_private_data *) channel->private_data;
 	EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 
+	mark_dirty(channel);
+
 #ifdef NO_IO_CACHE
 	return raw_write_blk(channel, data, block, count, buf, 0);
 #else
@@ -1440,6 +1473,8 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
 	if (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)
 		return errno;
 
+	mark_dirty(channel);
+
 	actual = write(data->dev, buf, size);
 	if (actual < 0)
 		return errno;
@@ -1455,7 +1490,7 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
 static errcode_t unix_flush(io_channel channel)
 {
 	struct unix_private_data *data;
-	errcode_t retval = 0;
+	errcode_t retval = 0, retval2;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	data = (struct unix_private_data *) channel->private_data;
@@ -1466,8 +1501,9 @@ static errcode_t unix_flush(io_channel channel)
 #endif
 #ifdef HAVE_FSYNC
 	/* always fsync the device, even if flushing our own cache failed */
-	if (fsync(data->dev) != 0 && !retval)
-		return errno;
+	retval2 = maybe_fsync(channel);
+	if (retval2 && !retval)
+		retval = retval2;
 #endif
 	return retval;
 }

[PATCH 05/10] libext2fs: invalidate cached blocks when freeing them

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

When we're freeing blocks, we should tell the IO manager to drop them
from any cache it might be maintaining to improve performance.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/ext2_io.h         |    8 +++++++-
 debian/libext2fs2t64.symbols |    1 +
 lib/ext2fs/alloc_stats.c     |    6 ++++++
 lib/ext2fs/io_manager.c      |    9 +++++++++
 lib/ext2fs/unix_io.c         |   35 +++++++++++++++++++++++++++++++++++
 5 files changed, 58 insertions(+), 1 deletion(-)


diff --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h
index f53983b30996b4..26ecd128954a0e 100644
--- a/lib/ext2fs/ext2_io.h
+++ b/lib/ext2fs/ext2_io.h
@@ -103,7 +103,10 @@ struct struct_io_manager {
 	errcode_t (*zeroout)(io_channel channel, unsigned long long block,
 			     unsigned long long count);
 	errcode_t (*get_fd)(io_channel channel, int *fd);
-	long	reserved[13];
+	errcode_t (*invalidate_blocks)(io_channel channel,
+				       unsigned long long block,
+				       unsigned long long count);
+	long	reserved[12];
 };
 
 #define IO_FLAG_RW		0x0001
@@ -147,6 +150,9 @@ extern errcode_t io_channel_cache_readahead(io_channel io,
 					    unsigned long long block,
 					    unsigned long long count);
 extern errcode_t io_channel_get_fd(io_channel io, int *fd);
+extern errcode_t io_channel_invalidate_blocks(io_channel io,
+					      unsigned long long block,
+					      unsigned long long count);
 
 #ifdef _WIN32
 /* windows_io.c */
diff --git a/debian/libext2fs2t64.symbols b/debian/libext2fs2t64.symbols
index 8e3214ee31e337..864a284b940009 100644
--- a/debian/libext2fs2t64.symbols
+++ b/debian/libext2fs2t64.symbols
@@ -694,6 +694,7 @@ libext2fs.so.2 libext2fs2t64 #MINVER#
  io_channel_cache_readahead@Base 1.43
  io_channel_discard@Base 1.42
  io_channel_get_fd@Base 1.47.99
+ io_channel_invalidate_blocks@Base 1.47.99
  io_channel_read_blk64@Base 1.41.1
  io_channel_set_options@Base 1.37
  io_channel_write_blk64@Base 1.41.1
diff --git a/lib/ext2fs/alloc_stats.c b/lib/ext2fs/alloc_stats.c
index 95a6438f252e0f..68bbe6807a8ed3 100644
--- a/lib/ext2fs/alloc_stats.c
+++ b/lib/ext2fs/alloc_stats.c
@@ -82,6 +82,9 @@ void ext2fs_block_alloc_stats2(ext2_filsys fs, blk64_t blk, int inuse)
 			     -inuse * (blk64_t) EXT2FS_CLUSTER_RATIO(fs));
 	ext2fs_mark_super_dirty(fs);
 	ext2fs_mark_bb_dirty(fs);
+	if (inuse < 0)
+		io_channel_invalidate_blocks(fs->io, blk,
+					     EXT2FS_CLUSTER_RATIO(fs));
 	if (fs->block_alloc_stats)
 		(fs->block_alloc_stats)(fs, (blk64_t) blk, inuse);
 }
@@ -144,11 +147,14 @@ void ext2fs_block_alloc_stats_range(ext2_filsys fs, blk64_t blk,
 		ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 		ext2fs_group_desc_csum_set(fs, group);
 		ext2fs_free_blocks_count_add(fs->super, -inuse * (blk64_t) n);
+
 		blk += n;
 		num -= n;
 	}
 	ext2fs_mark_super_dirty(fs);
 	ext2fs_mark_bb_dirty(fs);
+	if (inuse < 0)
+		io_channel_invalidate_blocks(fs->io, orig_blk, orig_num);
 	if (fs->block_alloc_stats_range)
 		(fs->block_alloc_stats_range)(fs, orig_blk, orig_num, inuse);
 }
diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
index 6b4dca5e4dbca2..c91fab4eb290d5 100644
--- a/lib/ext2fs/io_manager.c
+++ b/lib/ext2fs/io_manager.c
@@ -158,3 +158,12 @@ errcode_t io_channel_get_fd(io_channel io, int *fd)
 
 	return io->manager->get_fd(io, fd);
 }
+
+errcode_t io_channel_invalidate_blocks(io_channel io, unsigned long long block,
+				       unsigned long long count)
+{
+	if (!io->manager->invalidate_blocks)
+		return EXT2_ET_OP_NOT_SUPPORTED;
+
+	return io->manager->invalidate_blocks(io, block, count);
+}
diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index b462c587e3e2ac..be253b5fddf281 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -667,6 +667,25 @@ static errcode_t reuse_cache(io_channel channel,
 #define FLUSH_INVALIDATE	0x01
 #define FLUSH_NOLOCK		0x02
 
+/* Remove blocks from the cache.  Dirty contents are discarded. */
+static void invalidate_cached_blocks(io_channel channel,
+				     struct unix_private_data *data,
+				     unsigned long long block,
+				     unsigned long long count)
+{
+	struct unix_cache	*cache;
+	int			i;
+
+	mutex_lock(data, CACHE_MTX);
+	for (i = 0, cache = data->cache; i < data->cache_size; i++, cache++) {
+		if (!cache->in_use || cache->block < block ||
+		    cache->block >= block + count)
+			continue;
+		cache->in_use = 0;
+	}
+	mutex_unlock(data, CACHE_MTX);
+}
+
 /*
  * Flush all of the blocks in the cache
  */
@@ -1715,6 +1734,20 @@ static errcode_t unix_get_fd(io_channel channel, int *fd)
 	return 0;
 }
 
+static errcode_t unix_invalidate_blocks(io_channel channel,
+					unsigned long long block,
+					unsigned long long count)
+{
+	struct unix_private_data *data;
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	data = (struct unix_private_data *) channel->private_data;
+	EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+	invalidate_cached_blocks(channel, data, block, count);
+	return 0;
+}
+
 #if __GNUC_PREREQ (4, 6)
 #pragma GCC diagnostic pop
 #endif
@@ -1737,6 +1770,7 @@ static struct struct_io_manager struct_unix_manager = {
 	.cache_readahead	= unix_cache_readahead,
 	.zeroout	= unix_zeroout,
 	.get_fd		= unix_get_fd,
+	.invalidate_blocks = unix_invalidate_blocks,
 };
 
 io_manager unix_io_manager = &struct_unix_manager;
@@ -1759,6 +1793,7 @@ static struct struct_io_manager struct_unixfd_manager = {
 	.cache_readahead	= unix_cache_readahead,
 	.zeroout	= unix_zeroout,
 	.get_fd		= unix_get_fd,
+	.invalidate_blocks = unix_invalidate_blocks,
 };
 
 io_manager unixfd_io_manager = &struct_unixfd_manager;

[PATCH 06/10] libext2fs: only flush affected blocks in unix_write_byte

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

There's no need to invalidate the entire cache when writing a range of
bytes to the device.  The only ones we need to invalidate are the ones
that we're writing separately.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/unix_io.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)


diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index be253b5fddf281..d4973d1a878057 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -1468,6 +1468,7 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
 {
 	struct unix_private_data *data;
 	errcode_t	retval = 0;
+	unsigned long long bno, nbno;
 	ssize_t		actual;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
@@ -1483,10 +1484,17 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
 
 #ifndef NO_IO_CACHE
 	/*
-	 * Flush out the cache completely
+	 * Flush all the dirty blocks, then invalidate the blocks we're about
+	 * to write.
 	 */
-	if ((retval = flush_cached_blocks(channel, data, FLUSH_INVALIDATE)))
+	retval = flush_cached_blocks(channel, data, 0);
+	if (retval)
 		return retval;
+
+	bno = offset / channel->block_size;
+	nbno = (offset + size + channel->block_size - 1) / channel->block_size;
+
+	invalidate_cached_blocks(channel, data, bno, nbno - bno);
 #endif
 
 	if (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)

[PATCH 07/10] libext2fs: allow unix_write_byte when the write would be aligned

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

If someone calls write_byte on an IO channel with an alignment
requirement and the range to be written is aligned correctly, go ahead
and do the write.  This will be needed later when we try to speed up
superblock writes.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/unix_io.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)


diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index d4973d1a878057..068be689326443 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -1479,7 +1479,9 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
 #ifdef ALIGN_DEBUG
 		printf("unix_write_byte: O_DIRECT fallback\n");
 #endif
-		return EXT2_ET_UNIMPLEMENTED;
+		if (!IS_ALIGNED(data->offset + offset, channel->align) ||
+		    !IS_ALIGNED(data->offset + offset + size, channel->align))
+			return EXT2_ET_UNIMPLEMENTED;
 	}
 
 #ifndef NO_IO_CACHE

[PATCH 08/10] libext2fs: allow clients to ask to write full superblocks

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

write_primary_superblock currently does this weird dance where it will
try to write only the dirty bytes of the primary superblock to disk.  In
theory, this is done so that tune2fs can incrementally update superblock
bytes when the filesystem is mounted; ext2 was famous for allowing using
this dance to set new fs parameters and have them take effect in real
time.

The ability to do this safely was obliterated back in 2001 when ext3 was
introduced with journalling, because tune2fs has no way to know if the
journal has already logged an updated primary superblock but not yet
written it to disk, which means that they can race to write, and changes
can be lost.

This (non-)safety was further obliterated back in 2012 when I added
checksums to all the metadata blocks in ext4 because anyone else with
the block device open can see the primary superblock in an intermediate
state where the checksum does not match the superblock contents.

At this point in 2025 it's kind of stupid for fuse2fs to be doing this
because you can't have the kernel and fuse2fs mount the same filesystem
at the same time.  It also makes fuse2fs op_fsync slow because libext2fs
performs a bunch of small writes and introduce extra fsyncs.

So, add a new flag to ask for full superblock writes, which fuse2fs will
use later.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/ext2fs.h  |    1 +
 lib/ext2fs/closefs.c |    7 +++++++
 2 files changed, 8 insertions(+)


diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index bb2170b78d6308..dee9feb02624ed 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -220,6 +220,7 @@ typedef struct ext2_file *ext2_file_t;
 #define EXT2_FLAG_IBITMAP_TAIL_PROBLEM	0x2000000
 #define EXT2_FLAG_THREADS		0x4000000
 #define EXT2_FLAG_IGNORE_SWAP_DIRENT	0x8000000
+#define EXT2_FLAG_WRITE_FULL_SUPER	0x10000000
 
 /*
  * Internal flags for use by the ext2fs library only
diff --git a/lib/ext2fs/closefs.c b/lib/ext2fs/closefs.c
index 8e5bec03a050de..9a67db76e7b326 100644
--- a/lib/ext2fs/closefs.c
+++ b/lib/ext2fs/closefs.c
@@ -196,6 +196,13 @@ static errcode_t write_primary_superblock(ext2_filsys fs,
 	int		check_idx, write_idx, size;
 	errcode_t	retval;
 
+	if (fs->flags & EXT2_FLAG_WRITE_FULL_SUPER) {
+		retval = io_channel_write_byte(fs->io, SUPERBLOCK_OFFSET,
+					       SUPERBLOCK_SIZE, super);
+		if (!retval)
+			return 0;
+	}
+
 	if (!fs->io->manager->write_byte || !fs->orig_super) {
 	fallback:
 		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);

[PATCH 09/10] libext2fs: allow callers to disallow I/O to file data blocks

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add a flag to ext2_file_t to disallow read and write I/O to file data
blocks.  This supports fuse2fs iomap support, which will keep all the
file data I/O inside the kerne.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/ext2fs.h |    3 +++
 lib/ext2fs/fileio.c |   12 +++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)


diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index dee9feb02624ed..7d36b1a839dc57 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -178,6 +178,9 @@ typedef struct ext2_struct_dblist *ext2_dblist;
 #define EXT2_FILE_WRITE		0x0001
 #define EXT2_FILE_CREATE	0x0002
 
+/* no file I/O to disk blocks, only to inline data */
+#define EXT2_FILE_NOBLOCKIO	0x0004
+
 #define EXT2_FILE_MASK		0x00FF
 
 #define EXT2_FILE_BUF_DIRTY	0x4000
diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
index 3a36e9e7fff43b..95ee45ec7371ae 100644
--- a/lib/ext2fs/fileio.c
+++ b/lib/ext2fs/fileio.c
@@ -314,6 +314,11 @@ errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
 	if (file->inode.i_flags & EXT4_INLINE_DATA_FL)
 		return ext2fs_file_read_inline_data(file, buf, wanted, got);
 
+	if (file->flags & EXT2_FILE_NOBLOCKIO) {
+		retval = EXT2_ET_OP_NOT_SUPPORTED;
+		goto fail;
+	}
+
 	while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
 		retval = sync_buffer_position(file);
 		if (retval)
@@ -441,6 +446,11 @@ errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
 		retval = 0;
 	}
 
+	if (file->flags & EXT2_FILE_NOBLOCKIO) {
+		retval = EXT2_ET_OP_NOT_SUPPORTED;
+		goto fail;
+	}
+
 	while (nbytes > 0) {
 		retval = sync_buffer_position(file);
 		if (retval)
@@ -609,7 +619,7 @@ static errcode_t ext2fs_file_zero_past_offset(ext2_file_t file,
 	int ret_flags;
 	errcode_t retval;
 
-	if (off == 0)
+	if (off == 0 || (file->flags & EXT2_FILE_NOBLOCKIO))
 		return 0;
 
 	retval = sync_buffer_position(file);

[PATCH 10/10] libext2fs: add posix advisory locking to the unix IO manager

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add support for using flock() to protect the files opened by the Unix IO
manager so that we can't mount the same fs multiple times.  This also
prevents systemd and udev from accessing the device while e2fsprogs is
doing something with the device.

Link: https://systemd.io/BLOCK_DEVICE_LOCKING/
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/unix_io.c |   64 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)


diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 068be689326443..55007ad7d2ae15 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -65,6 +65,12 @@
 #include <pthread.h>
 #endif
 
+#if defined(HAVE_SYS_FILE_H) && defined(HAVE_SIGNAL_H)
+# include <sys/file.h>
+# include <signal.h>
+# define WANT_LOCK_UNIX_FD
+#endif
+
 #if defined(__linux__) && defined(_IO) && !defined(BLKROGET)
 #define BLKROGET   _IO(0x12, 94) /* Get read-only status (0 = read_write).  */
 #endif
@@ -149,6 +155,9 @@ struct unix_private_data {
 	pthread_mutex_t bounce_mutex;
 	pthread_mutex_t stats_mutex;
 #endif
+#ifdef WANT_LOCK_UNIX_FD
+	int	lock_flags;
+#endif
 };
 
 #define IS_ALIGNED(n, align) ((((uintptr_t) n) & \
@@ -897,6 +906,47 @@ int ext2fs_fstat(int fd, ext2fs_struct_stat *buf)
 #endif
 }
 
+#ifdef WANT_LOCK_UNIX_FD
+static void unix_lock_alarm_handler(int signal, siginfo_t *data, void *p)
+{
+	/* do nothing, the signal will abort the flock operation */
+}
+
+static int unix_lock_fd(int fd, int flags)
+{
+	struct sigaction newsa = {
+		.sa_flags = SA_SIGINFO,
+		.sa_sigaction = unix_lock_alarm_handler,
+	};
+	struct sigaction oldsa;
+	const int operation = (flags & IO_FLAG_EXCLUSIVE) ? LOCK_EX : LOCK_SH;
+	int ret;
+
+	/* wait five seconds for the lock */
+	ret = sigaction(SIGALRM, &newsa, &oldsa);
+	if (ret)
+		return ret;
+
+	alarm(5);
+
+	ret = flock(fd, operation);
+	if (ret == 0)
+		ret = operation;
+	else if (errno == EINTR) {
+		errno = EWOULDBLOCK;
+		ret = -1;
+	}
+
+	alarm(0);
+	sigaction(SIGALRM, &oldsa, NULL);
+	return ret;
+}
+
+static void unix_unlock_fd(int fd)
+{
+	flock(fd, LOCK_UN);
+}
+#endif
 
 static errcode_t unix_open_channel(const char *name, int fd,
 				   int flags, io_channel *channel,
@@ -935,6 +985,16 @@ static errcode_t unix_open_channel(const char *name, int fd,
 	if (retval)
 		goto cleanup;
 
+#ifdef WANT_LOCK_UNIX_FD
+	if (flags & IO_FLAG_RW) {
+		data->lock_flags = unix_lock_fd(fd, flags);
+		if (data->lock_flags < 0) {
+			retval = errno;
+			goto cleanup;
+		}
+	}
+#endif
+
 	strcpy(io->name, name);
 	io->private_data = data;
 	io->block_size = 1024;
@@ -1200,6 +1260,10 @@ static errcode_t unix_close(io_channel channel)
 	if (retval2 && !retval)
 		retval = retval2;
 
+#ifdef WANT_LOCK_UNIX_FD
+	if (data->lock_flags)
+		unix_unlock_fd(data->dev);
+#endif
 	if (close(data->dev) < 0 && !retval)
 		retval = errno;
 	free_cache(data);

[PATCH 01/17] fuse2fs: implement bare minimum iomap for file mapping reporting

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add enough of an iomap implementation that we can do FIEMAP and
SEEK_DATA and SEEK_HOLE.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 configure         |   48 +++++
 configure.ac      |   31 +++
 fuse4fs/fuse4fs.c |  525 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 lib/config.h.in   |    3 
 misc/fuse2fs.c    |  525 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 5 files changed, 1118 insertions(+), 14 deletions(-)


diff --git a/configure b/configure
index 7f5fb7c1a62084..4137f942efaef5 100755
--- a/configure
+++ b/configure
@@ -14212,6 +14212,7 @@ printf "%s\n" "yes" >&6; }
 fi
 
 
+have_fuse_iomap=
 if test -n "$FUSE_LIB"
 then
 	FUSE_USE_VERSION=314
@@ -14237,12 +14238,59 @@ See \`config.log' for more details" "$LINENO" 5; }
 fi
 
 done
+
+					{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for iomap_begin in libfuse" >&5
+printf %s "checking for iomap_begin in libfuse... " >&6; }
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+	#define _GNU_SOURCE
+	#define _FILE_OFFSET_BITS	64
+	#define FUSE_USE_VERSION	399
+	#include <fuse.h>
+
+int
+main (void)
+{
+
+	struct fuse_operations fs_ops = {
+		.iomap_begin = NULL,
+		.iomap_end = NULL,
+	};
+	struct fuse_file_iomap narf = { };
+
+  ;
+  return 0;
+}
+
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  have_fuse_iomap=yes
+	   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; }
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+	if test "$have_fuse_iomap" = yes
+	then
+		FUSE_USE_VERSION=399
+	fi
 fi
 if test -n "$FUSE_USE_VERSION"
 then
 
 printf "%s\n" "#define FUSE_USE_VERSION $FUSE_USE_VERSION" >>confdefs.h
 
+fi
+if test -n "$have_fuse_iomap"
+then
+
+printf "%s\n" "#define HAVE_FUSE_IOMAP 1" >>confdefs.h
+
 fi
 
 have_fuse_lowlevel=
diff --git a/configure.ac b/configure.ac
index 2eb11873ea0e50..a1057c07b8c056 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1382,6 +1382,7 @@ dnl
 dnl Set FUSE_USE_VERSION, which is how fuse servers build against a particular
 dnl libfuse ABI.  Currently we link against the libfuse 3.14 ABI (hence 314)
 dnl
+have_fuse_iomap=
 if test -n "$FUSE_LIB"
 then
 	FUSE_USE_VERSION=314
@@ -1391,12 +1392,42 @@ then
 		[AC_MSG_FAILURE([Cannot build against fuse3 headers])],
 [#define _FILE_OFFSET_BITS	64
 #define FUSE_USE_VERSION	314])
+
+	dnl
+	dnl Check if the fuse library supports iomap, which requires a higher
+	dnl FUSE_USE_VERSION ABI version (3.99)
+	dnl
+	AC_MSG_CHECKING(for iomap_begin in libfuse)
+	AC_LINK_IFELSE(
+	[	AC_LANG_PROGRAM([[
+	#define _GNU_SOURCE
+	#define _FILE_OFFSET_BITS	64
+	#define FUSE_USE_VERSION	399
+	#include <fuse.h>
+		]], [[
+	struct fuse_operations fs_ops = {
+		.iomap_begin = NULL,
+		.iomap_end = NULL,
+	};
+	struct fuse_file_iomap narf = { };
+		]])
+	], have_fuse_iomap=yes
+	   AC_MSG_RESULT(yes),
+	   AC_MSG_RESULT(no))
+	if test "$have_fuse_iomap" = yes
+	then
+		FUSE_USE_VERSION=399
+	fi
 fi
 if test -n "$FUSE_USE_VERSION"
 then
 	AC_DEFINE_UNQUOTED(FUSE_USE_VERSION, $FUSE_USE_VERSION,
 		[Define to the version of FUSE to use])
 fi
+if test -n "$have_fuse_iomap"
+then
+	AC_DEFINE(HAVE_FUSE_IOMAP, 1, [Define to 1 if fuse supports iomap])
+fi
 
 dnl
 dnl Check if the FUSE lowlevel library is supported
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 9a6913f6eef16a..bf9c2081702132 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -143,6 +143,9 @@ static inline uint64_t round_down(uint64_t b, unsigned int align)
 	return b - m;
 }
 
+#define max(a, b)	((a) > (b) ? (a) : (b))
+#define min(a, b)	((a) < (b) ? (a) : (b))
+
 #define dbg_printf(fuse4fs, format, ...) \
 	while ((fuse4fs)->debug) { \
 		printf("FUSE4FS (%s): tid=%d " format, (fuse4fs)->shortdev, gettid(), ##__VA_ARGS__); \
@@ -220,6 +223,14 @@ enum fuse4fs_opstate {
 	F4OP_SHUTDOWN,
 };
 
+#ifdef HAVE_FUSE_IOMAP
+enum fuse4fs_iomap_state {
+	IOMAP_DISABLED,
+	IOMAP_UNKNOWN,
+	IOMAP_ENABLED,
+};
+#endif
+
 /* Main program context */
 #define FUSE4FS_MAGIC		(0xEF53DEADUL)
 struct fuse4fs {
@@ -248,6 +259,9 @@ struct fuse4fs {
 	enum fuse4fs_opstate opstate;
 	int logfd;
 	int blocklog;
+#ifdef HAVE_FUSE_IOMAP
+	enum fuse4fs_iomap_state iomap_state;
+#endif
 	unsigned int blockmask;
 	unsigned long offset;
 	unsigned int next_generation;
@@ -700,6 +714,15 @@ static inline void __fuse4fs_finish(struct fuse4fs *ff, int ret,
 }
 #define fuse4fs_finish(ff, ret) __fuse4fs_finish((ff), (ret), __func__)
 
+#ifdef HAVE_FUSE_IOMAP
+static inline int fuse4fs_iomap_enabled(const struct fuse4fs *ff)
+{
+	return ff->iomap_state >= IOMAP_ENABLED;
+}
+#else
+# define fuse4fs_iomap_enabled(...)	(0)
+#endif
+
 static void get_now(struct timespec *now)
 {
 #ifdef CLOCK_REALTIME
@@ -1122,7 +1145,7 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
 {
 	char options[128];
 	int flags = EXT2_FLAG_64BITS | EXT2_FLAG_THREADS | EXT2_FLAG_RW |
-		    libext2_flags;
+		    EXT2_FLAG_WRITE_FULL_SUPER | libext2_flags;
 	errcode_t err;
 
 	if (ff->lockfile) {
@@ -1494,6 +1517,33 @@ static inline int fuse_set_feature_flag(struct fuse_conn_info *conn,
 }
 #endif
 
+#ifdef HAVE_FUSE_IOMAP
+static void fuse4fs_iomap_enable(struct fuse_conn_info *conn,
+				 struct fuse4fs *ff)
+{
+	/* Don't let anyone touch iomap until the end of the patchset. */
+	ff->iomap_state = IOMAP_DISABLED;
+	return;
+
+	/* iomap only works with block devices */
+	if (ff->iomap_state != IOMAP_DISABLED && fuse4fs_on_bdev(ff) &&
+	    fuse_set_feature_flag(conn, FUSE_CAP_IOMAP)) {
+		/*
+		 * If we're mounting in iomap mode, we need to unmount in
+		 * op_destroy so that the block device will be released before
+		 * umount(2) returns.
+		 */
+		ff->unmount_in_destroy = 1;
+		ff->iomap_state = IOMAP_ENABLED;
+	}
+
+	if (ff->iomap_state == IOMAP_UNKNOWN)
+		ff->iomap_state = IOMAP_DISABLED;
+}
+#else
+# define fuse4fs_iomap_enable(...)	((void)0)
+#endif
+
 static void op_init(void *userdata, struct fuse_conn_info *conn)
 {
 	struct fuse4fs *ff = userdata;
@@ -1516,6 +1566,7 @@ static void op_init(void *userdata, struct fuse_conn_info *conn)
 #ifdef FUSE_CAP_NO_EXPORT_SUPPORT
 	fuse_set_feature_flag(conn, FUSE_CAP_NO_EXPORT_SUPPORT);
 #endif
+	fuse4fs_iomap_enable(conn, ff);
 	conn->time_gran = 1;
 
 	if (ff->kernel) {
@@ -5402,6 +5453,460 @@ static void op_fallocate(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 }
 #endif /* SUPPORT_FALLOCATE */
 
+#ifdef HAVE_FUSE_IOMAP
+static void fuse4fs_iomap_hole(struct fuse4fs *ff, struct fuse_file_iomap *iomap,
+			       off_t pos, uint64_t count)
+{
+	iomap->dev = FUSE_IOMAP_DEV_NULL;
+	iomap->addr = FUSE_IOMAP_NULL_ADDR;
+	iomap->offset = pos;
+	iomap->length = count;
+	iomap->type = FUSE_IOMAP_TYPE_HOLE;
+}
+
+static void fuse4fs_iomap_hole_to_eof(struct fuse4fs *ff,
+				      struct fuse_file_iomap *iomap, off_t pos,
+				      off_t count,
+				      const struct ext2_inode_large *inode)
+{
+	ext2_filsys fs = ff->fs;
+	uint64_t isize = EXT2_I_SIZE(inode);
+
+	/*
+	 * We have to be careful about handling a hole to the right of the
+	 * entire mapping tree.  First, the mapping must start and end on a
+	 * block boundary because they must be aligned to at least an LBA for
+	 * the block layer; and to the fsblock for smoother operation.
+	 *
+	 * As for the length -- we could return a mapping all the way to
+	 * i_size, but i_size could be less than pos/count if we're zeroing the
+	 * EOF block in anticipation of a truncate operation.  Similarly, we
+	 * don't want to end the mapping at pos+count because we know there's
+	 * nothing mapped byeond here.
+	 */
+	uint64_t startoff = round_down(pos, fs->blocksize);
+	uint64_t eofoff = round_up(max(pos + count, isize), fs->blocksize);
+
+	dbg_printf(ff,
+ "pos=0x%llx count=0x%llx isize=0x%llx startoff=0x%llx eofoff=0x%llx\n",
+		   (unsigned long long)pos,
+		   (unsigned long long)count,
+		   (unsigned long long)isize,
+		   (unsigned long long)startoff,
+		   (unsigned long long)eofoff);
+
+	fuse4fs_iomap_hole(ff, iomap, startoff, eofoff - startoff);
+}
+
+#define DEBUG_IOMAP
+#ifdef DEBUG_IOMAP
+# define __DUMP_EXTENT(ff, func, tag, startoff, err, extent) \
+	do { \
+		dbg_printf((ff), \
+ "%s: %s startoff 0x%llx err %ld lblk 0x%llx pblk 0x%llx len 0x%x flags 0x%x\n", \
+			   (func), (tag), (startoff), (err), (extent)->e_lblk, \
+			   (extent)->e_pblk, (extent)->e_len, \
+			   (extent)->e_flags & EXT2_EXTENT_FLAGS_UNINIT); \
+	} while(0)
+# define DUMP_EXTENT(ff, tag, startoff, err, extent) \
+	__DUMP_EXTENT((ff), __func__, (tag), (startoff), (err), (extent))
+
+# define __DUMP_INFO(ff, func, tag, startoff, err, info) \
+	do { \
+		dbg_printf((ff), \
+ "%s: %s startoff 0x%llx err %ld entry %d/%d/%d level  %d/%d\n", \
+			   (func), (tag), (startoff), (err), \
+			   (info)->curr_entry, (info)->num_entries, \
+			   (info)->max_entries, (info)->curr_level, \
+			   (info)->max_depth); \
+	} while(0)
+# define DUMP_INFO(ff, tag, startoff, err, info) \
+	__DUMP_INFO((ff), __func__, (tag), (startoff), (err), (info))
+#else
+# define __DUMP_EXTENT(...)	((void)0)
+# define DUMP_EXTENT(...)	((void)0)
+# define DUMP_INFO(...)		((void)0)
+#endif
+
+static inline errcode_t __fuse4fs_get_mapping_at(struct fuse4fs *ff,
+						 ext2_extent_handle_t handle,
+						 blk64_t startoff,
+						 struct ext2fs_extent *bmap,
+						 const char *func)
+{
+	errcode_t err;
+
+	/*
+	 * Find the file mapping at startoff.  We don't check the return value
+	 * of _goto because _get will error out if _goto failed.  There's a
+	 * subtlety to the outcome of _goto when startoff falls in a sparse
+	 * hole however:
+	 *
+	 * Most of the time, _goto points the cursor at the mapping whose lblk
+	 * is just to the left of startoff.  The mapping may or may not overlap
+	 * startoff; this is ok.  In other words, the tree lookup behaves as if
+	 * we asked it to use a less than or equals comparison.
+	 *
+	 * However, if startoff is to the left of the first mapping in the
+	 * extent tree, _goto points the cursor at that first mapping because
+	 * it doesn't know how to deal with this situation.  In this case,
+	 * the tree lookup behaves as if we asked it to use a greater than
+	 * or equals comparison.
+	 *
+	 * Note: If _get() returns 'no current node', that means that there
+	 * aren't any mappings at all.
+	 */
+	ext2fs_extent_goto(handle, startoff);
+	err = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, bmap);
+	__DUMP_EXTENT(ff, func, "lookup", startoff, err, bmap);
+	if (err == EXT2_ET_NO_CURRENT_NODE)
+		err = EXT2_ET_EXTENT_NOT_FOUND;
+	return err;
+}
+
+static inline errcode_t __fuse4fs_get_next_mapping(struct fuse4fs *ff,
+						   ext2_extent_handle_t handle,
+						   blk64_t startoff,
+						   struct ext2fs_extent *bmap,
+						   const char *func)
+{
+	struct ext2fs_extent newex;
+	struct ext2_extent_info info;
+	errcode_t err;
+
+	/*
+	 * The extent tree code has this (probably broken) behavior that if
+	 * more than two of the highest levels of the cursor point at the
+	 * rightmost edge of an extent tree block, a _NEXT_LEAF movement fails
+	 * to move the cursor position of any of the lower levels.  IOWs, if
+	 * leaf level N is at the right edge, it will only advance level N-1
+	 * to the right.  If N-1 was at the right edge, the cursor resets to
+	 * record 0 of that level and goes down to the wrong leaf.
+	 *
+	 * Work around this by walking up (towards root level 0) the extent
+	 * tree until we find a level where we're not already at the rightmost
+	 * edge.  The _NEXT_LEAF movement will walk down the tree to find the
+	 * leaves.
+	 */
+	err = ext2fs_extent_get_info(handle, &info);
+	DUMP_INFO(ff, "UP?", startoff, err, &info);
+	if (err)
+		return err;
+
+	while (info.curr_entry == info.num_entries && info.curr_level > 0) {
+		err = ext2fs_extent_get(handle, EXT2_EXTENT_UP, &newex);
+		DUMP_EXTENT(ff, "UP", startoff, err, &newex);
+		if (err)
+			return err;
+		err = ext2fs_extent_get_info(handle, &info);
+		DUMP_INFO(ff, "UP", startoff, err, &info);
+		if (err)
+			return err;
+	}
+
+	/*
+	 * If we're at the root and there are no more entries, there's nothing
+	 * else to be found.
+	 */
+	if (info.curr_level == 0 && info.curr_entry == info.num_entries)
+		return EXT2_ET_EXTENT_NOT_FOUND;
+
+	/* Otherwise grab this next leaf and return it. */
+	err = ext2fs_extent_get(handle, EXT2_EXTENT_NEXT_LEAF, &newex);
+	DUMP_EXTENT(ff, "NEXT", startoff, err, &newex);
+	if (err)
+		return err;
+
+	*bmap = newex;
+	return 0;
+}
+
+#define fuse4fs_get_mapping_at(ff, handle, startoff, bmap) \
+	__fuse4fs_get_mapping_at((ff), (handle), (startoff), (bmap), __func__)
+#define fuse4fs_get_next_mapping(ff, handle, startoff, bmap) \
+	__fuse4fs_get_next_mapping((ff), (handle), (startoff), (bmap), __func__)
+
+static errcode_t fuse4fs_iomap_begin_extent(struct fuse4fs *ff, uint64_t ino,
+					    struct ext2_inode_large *inode,
+					    off_t pos, uint64_t count,
+					    uint32_t opflags,
+					    struct fuse_file_iomap *iomap)
+{
+	ext2_extent_handle_t handle;
+	struct ext2fs_extent extent = { };
+	ext2_filsys fs = ff->fs;
+	const blk64_t startoff = FUSE4FS_B_TO_FSBT(ff, pos);
+	errcode_t err;
+	int ret = 0;
+
+	err = ext2fs_extent_open2(fs, ino, EXT2_INODE(inode), &handle);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = fuse4fs_get_mapping_at(ff, handle, startoff, &extent);
+	if (err == EXT2_ET_EXTENT_NOT_FOUND) {
+		/* No mappings at all; the whole range is a hole. */
+		fuse4fs_iomap_hole_to_eof(ff, iomap, pos, count, inode);
+		goto out_handle;
+	}
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_handle;
+	}
+
+	if (startoff < extent.e_lblk) {
+		/*
+		 * Mapping starts to the right of the current position.
+		 * Synthesize a hole going to that next extent.
+		 */
+		fuse4fs_iomap_hole(ff, iomap, FUSE4FS_FSB_TO_B(ff, startoff),
+				FUSE4FS_FSB_TO_B(ff, extent.e_lblk - startoff));
+		goto out_handle;
+	}
+
+	if (startoff >= extent.e_lblk + extent.e_len) {
+		/*
+		 * Mapping ends to the left of the current position.  Try to
+		 * find the next mapping.  If there is no next mapping, the
+		 * whole range is in a hole.
+		 */
+		err = fuse4fs_get_next_mapping(ff, handle, startoff, &extent);
+		if (err == EXT2_ET_EXTENT_NOT_FOUND) {
+			fuse4fs_iomap_hole_to_eof(ff, iomap, pos, count, inode);
+			goto out_handle;
+		}
+
+		/*
+		 * If the new mapping starts to the right of startoff, there's
+		 * a hole from startoff to the start of the new mapping.
+		 */
+		if (startoff < extent.e_lblk) {
+			fuse4fs_iomap_hole(ff, iomap,
+				FUSE4FS_FSB_TO_B(ff, startoff),
+				FUSE4FS_FSB_TO_B(ff, extent.e_lblk - startoff));
+			goto out_handle;
+		}
+
+		/*
+		 * The new mapping starts at startoff.  Something weird
+		 * happened in the extent tree lookup, but we found a valid
+		 * mapping so we'll run with it.
+		 */
+	}
+
+	/* Mapping overlaps startoff, report this. */
+	iomap->dev = FUSE_IOMAP_DEV_NULL;
+	iomap->addr = FUSE4FS_FSB_TO_B(ff, extent.e_pblk);
+	iomap->offset = FUSE4FS_FSB_TO_B(ff, extent.e_lblk);
+	iomap->length = FUSE4FS_FSB_TO_B(ff, extent.e_len);
+	if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
+		iomap->type = FUSE_IOMAP_TYPE_UNWRITTEN;
+	else
+		iomap->type = FUSE_IOMAP_TYPE_MAPPED;
+
+out_handle:
+	ext2fs_extent_free(handle);
+	return ret;
+}
+
+static int fuse4fs_iomap_begin_indirect(struct fuse4fs *ff, uint64_t ino,
+					struct ext2_inode_large *inode,
+					off_t pos, uint64_t count,
+					uint32_t opflags,
+					struct fuse_file_iomap *iomap)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t startoff = FUSE4FS_B_TO_FSBT(ff, pos);
+	uint64_t isize = EXT2_I_SIZE(inode);
+	uint64_t real_count = min(count, 131072);
+	const blk64_t endoff = FUSE4FS_B_TO_FSB(ff, pos + real_count);
+	blk64_t startblock;
+	errcode_t err;
+
+	err = ext2fs_bmap2(fs, ino, EXT2_INODE(inode), NULL, 0, startoff, NULL,
+			   &startblock);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	iomap->dev = FUSE_IOMAP_DEV_NULL;
+	iomap->offset = FUSE4FS_FSB_TO_B(ff, startoff);
+	iomap->flags |= FUSE_IOMAP_F_MERGED;
+	if (startblock) {
+		iomap->addr = FUSE4FS_FSB_TO_B(ff, startblock);
+		iomap->type = FUSE_IOMAP_TYPE_MAPPED;
+	} else {
+		iomap->addr = FUSE_IOMAP_NULL_ADDR;
+		iomap->type = FUSE_IOMAP_TYPE_HOLE;
+	}
+	iomap->length = fs->blocksize;
+
+	/* See how long the mapping goes for. */
+	for (startoff++; startoff < endoff; startoff++) {
+		blk64_t prev_startblock = startblock;
+
+		err = ext2fs_bmap2(fs, ino, EXT2_INODE(inode), NULL, 0,
+				   startoff, NULL, &startblock);
+		if (err)
+			break;
+
+		if (iomap->type == FUSE_IOMAP_TYPE_MAPPED) {
+			if (startblock == prev_startblock + 1)
+				iomap->length += fs->blocksize;
+			else
+				break;
+		} else {
+			if (startblock == 0)
+				iomap->length += fs->blocksize;
+			else
+				break;
+		}
+	}
+
+	/*
+	 * If this is a hole that goes beyond EOF, report this as a hole to the
+	 * end of the range queried so that FIEMAP doesn't go mad.
+	 */
+	if (iomap->type == FUSE_IOMAP_TYPE_HOLE &&
+	    iomap->offset + iomap->length >= isize)
+		fuse4fs_iomap_hole_to_eof(ff, iomap, pos, count, inode);
+
+	return 0;
+}
+
+static int fuse4fs_iomap_begin_inline(struct fuse4fs *ff, ext2_ino_t ino,
+				      struct ext2_inode_large *inode, off_t pos,
+				      uint64_t count, struct fuse_file_iomap *iomap)
+{
+	uint64_t one_fsb = FUSE4FS_FSB_TO_B(ff, 1);
+
+	if (pos >= one_fsb) {
+		fuse4fs_iomap_hole_to_eof(ff, iomap, pos, count, inode);
+	} else {
+		/* ext4 only supports inline data files up to 1 fsb */
+		iomap->dev = FUSE_IOMAP_DEV_NULL;
+		iomap->addr = FUSE_IOMAP_NULL_ADDR;
+		iomap->offset = 0;
+		iomap->length = one_fsb;
+		iomap->type = FUSE_IOMAP_TYPE_INLINE;
+	}
+
+	return 0;
+}
+
+static int fuse4fs_iomap_begin_report(struct fuse4fs *ff, ext2_ino_t ino,
+				      struct ext2_inode_large *inode,
+				      off_t pos, uint64_t count,
+				      uint32_t opflags,
+				      struct fuse_file_iomap *read)
+{
+	if (inode->i_flags & EXT4_INLINE_DATA_FL)
+		return fuse4fs_iomap_begin_inline(ff, ino, inode, pos, count,
+						  read);
+
+	if (inode->i_flags & EXT4_EXTENTS_FL)
+		return fuse4fs_iomap_begin_extent(ff, ino, inode, pos, count,
+						  opflags, read);
+
+	return fuse4fs_iomap_begin_indirect(ff, ino, inode, pos, count,
+					    opflags, read);
+}
+
+static int fuse4fs_iomap_begin_read(struct fuse4fs *ff, ext2_ino_t ino,
+				    struct ext2_inode_large *inode, off_t pos,
+				    uint64_t count, uint32_t opflags,
+				    struct fuse_file_iomap *read)
+{
+	return -ENOSYS;
+}
+
+static int fuse4fs_iomap_begin_write(struct fuse4fs *ff, ext2_ino_t ino,
+				     struct ext2_inode_large *inode, off_t pos,
+				     uint64_t count, uint32_t opflags,
+				     struct fuse_file_iomap *read)
+{
+	return -ENOSYS;
+}
+
+static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
+			   off_t pos, uint64_t count, uint32_t opflags)
+{
+	struct fuse4fs *ff = fuse4fs_get(req);
+	struct ext2_inode_large inode;
+	struct fuse_file_iomap read = { };
+	ext2_filsys fs;
+	ext2_ino_t ino;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+
+	dbg_printf(ff, "%s: ino=%d pos=0x%llx count=0x%llx opflags=0x%x\n",
+		   __func__, ino,
+		   (unsigned long long)pos,
+		   (unsigned long long)count,
+		   opflags);
+
+	fs = fuse4fs_start(ff);
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_unlock;
+	}
+
+	if (opflags & FUSE_IOMAP_OP_REPORT)
+		ret = fuse4fs_iomap_begin_report(ff, ino, &inode, pos, count,
+						 opflags, &read);
+	else if (fuse_iomap_is_write(opflags))
+		ret = fuse4fs_iomap_begin_write(ff, ino, &inode, pos, count,
+						opflags, &read);
+	else
+		ret = fuse4fs_iomap_begin_read(ff, ino, &inode, pos, count,
+					       opflags, &read);
+	if (ret)
+		goto out_unlock;
+
+	dbg_printf(ff,
+ "%s: ino=%d pos=0x%llx -> addr=0x%llx offset=0x%llx length=0x%llx type=%u flags=0x%x\n",
+		   __func__, ino,
+		   (unsigned long long)pos,
+		   (unsigned long long)read.addr,
+		   (unsigned long long)read.offset,
+		   (unsigned long long)read.length,
+		   read.type,
+		   read.flags);
+
+out_unlock:
+	fuse4fs_finish(ff, ret);
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_iomap_begin(req, &read, NULL);
+}
+
+static void op_iomap_end(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
+			 off_t pos, uint64_t count, uint32_t opflags,
+			 ssize_t written, const struct fuse_file_iomap *iomap)
+{
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_ino_t ino;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+
+	dbg_printf(ff,
+ "%s: ino=%d pos=0x%llx count=0x%llx opflags=0x%x written=0x%zx mapflags=0x%x\n",
+		   __func__, ino,
+		   (unsigned long long)pos,
+		   (unsigned long long)count,
+		   opflags,
+		   written,
+		   iomap->flags);
+
+	fuse_reply_err(req, 0);
+}
+#endif /* HAVE_FUSE_IOMAP */
+
 static struct fuse_lowlevel_ops fs_ops = {
 	.lookup = op_lookup,
 	.setattr = op_setattr,
@@ -5445,6 +5950,10 @@ static struct fuse_lowlevel_ops fs_ops = {
 #ifdef SUPPORT_FALLOCATE
 	.fallocate = op_fallocate,
 #endif
+#ifdef HAVE_FUSE_IOMAP
+	.iomap_begin = op_iomap_begin,
+	.iomap_end = op_iomap_end,
+#endif /* HAVE_FUSE_IOMAP */
 };
 
 static int get_random_bytes(void *p, size_t sz)
@@ -5768,17 +6277,19 @@ static int fuse4fs_main(struct fuse_args *args, struct fuse4fs *ff)
 int main(int argc, char *argv[])
 {
 	struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
-	struct fuse4fs fctx;
+	struct fuse4fs fctx = {
+		.magic = FUSE4FS_MAGIC,
+		.opstate = F4OP_WRITABLE,
+		.logfd = -1,
+#ifdef HAVE_FUSE_IOMAP
+		.iomap_state = IOMAP_UNKNOWN,
+#endif
+	};
 	errcode_t err;
 	FILE *orig_stderr = stderr;
 	char extra_args[BUFSIZ];
 	int ret;
 
-	memset(&fctx, 0, sizeof(fctx));
-	fctx.magic = FUSE4FS_MAGIC;
-	fctx.logfd = -1;
-	fctx.opstate = F4OP_WRITABLE;
-
 	ret = fuse_opt_parse(&args, &fctx, fuse4fs_opts, fuse4fs_opt_proc);
 	if (ret)
 		exit(1);
diff --git a/lib/config.h.in b/lib/config.h.in
index c3379758c3c9bc..55e515020af422 100644
--- a/lib/config.h.in
+++ b/lib/config.h.in
@@ -76,6 +76,9 @@
 /* Define to 1 if fuse supports lowlevel API */
 #undef HAVE_FUSE_LOWLEVEL
 
+/* Define to 1 if fuse supports iomap */
+#undef HAVE_FUSE_IOMAP
+
 /* Define to 1 if you have the Mac OS X function
    CFLocaleCopyPreferredLanguages in the CoreFoundation framework. */
 #undef HAVE_CFLOCALECOPYPREFERREDLANGUAGES
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 6290d22f2b9658..ca61fbc89f5fda 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -137,6 +137,9 @@ static inline uint64_t round_down(uint64_t b, unsigned int align)
 	return b - m;
 }
 
+#define max(a, b)	((a) > (b) ? (a) : (b))
+#define min(a, b)	((a) < (b) ? (a) : (b))
+
 #define dbg_printf(fuse2fs, format, ...) \
 	while ((fuse2fs)->debug) { \
 		printf("FUSE2FS (%s): tid=%d " format, (fuse2fs)->shortdev, gettid(), ##__VA_ARGS__); \
@@ -213,6 +216,14 @@ enum fuse2fs_opstate {
 	F2OP_SHUTDOWN,
 };
 
+#ifdef HAVE_FUSE_IOMAP
+enum fuse2fs_iomap_state {
+	IOMAP_DISABLED,
+	IOMAP_UNKNOWN,
+	IOMAP_ENABLED,
+};
+#endif
+
 /* Main program context */
 #define FUSE2FS_MAGIC		(0xEF53DEADUL)
 struct fuse2fs {
@@ -241,6 +252,9 @@ struct fuse2fs {
 	enum fuse2fs_opstate opstate;
 	int logfd;
 	int blocklog;
+#ifdef HAVE_FUSE_IOMAP
+	enum fuse2fs_iomap_state iomap_state;
+#endif
 	unsigned int blockmask;
 	unsigned long offset;
 	unsigned int next_generation;
@@ -536,6 +550,15 @@ static inline void __fuse2fs_finish(struct fuse2fs *ff, int ret,
 }
 #define fuse2fs_finish(ff, ret) __fuse2fs_finish((ff), (ret), __func__)
 
+#ifdef HAVE_FUSE_IOMAP
+static inline int fuse2fs_iomap_enabled(const struct fuse2fs *ff)
+{
+	return ff->iomap_state >= IOMAP_ENABLED;
+}
+#else
+# define fuse2fs_iomap_enabled(...)	(0)
+#endif
+
 static void get_now(struct timespec *now)
 {
 #ifdef CLOCK_REALTIME
@@ -932,7 +955,7 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff, int libext2_flags)
 {
 	char options[128];
 	int flags = EXT2_FLAG_64BITS | EXT2_FLAG_THREADS | EXT2_FLAG_RW |
-		    libext2_flags;
+		    EXT2_FLAG_WRITE_FULL_SUPER | libext2_flags;
 	errcode_t err;
 
 	if (ff->lockfile) {
@@ -1300,6 +1323,33 @@ static inline int fuse_set_feature_flag(struct fuse_conn_info *conn,
 }
 #endif
 
+#ifdef HAVE_FUSE_IOMAP
+static void fuse2fs_iomap_enable(struct fuse_conn_info *conn,
+				 struct fuse2fs *ff)
+{
+	/* Don't let anyone touch iomap until the end of the patchset. */
+	ff->iomap_state = IOMAP_DISABLED;
+	return;
+
+	/* iomap only works with block devices */
+	if (ff->iomap_state != IOMAP_DISABLED && fuse2fs_on_bdev(ff) &&
+	    fuse_set_feature_flag(conn, FUSE_CAP_IOMAP)) {
+		/*
+		 * If we're mounting in iomap mode, we need to unmount in
+		 * op_destroy so that the block device will be released before
+		 * umount(2) returns.
+		 */
+		ff->unmount_in_destroy = 1;
+		ff->iomap_state = IOMAP_ENABLED;
+	}
+
+	if (ff->iomap_state == IOMAP_UNKNOWN)
+		ff->iomap_state = IOMAP_DISABLED;
+}
+#else
+# define fuse2fs_iomap_enable(...)	((void)0)
+#endif
+
 static void *op_init(struct fuse_conn_info *conn,
 		     struct fuse_config *cfg EXT2FS_ATTR((unused)))
 {
@@ -1333,6 +1383,8 @@ static void *op_init(struct fuse_conn_info *conn,
 #ifdef FUSE_CAP_NO_EXPORT_SUPPORT
 	fuse_set_feature_flag(conn, FUSE_CAP_NO_EXPORT_SUPPORT);
 #endif
+	fuse2fs_iomap_enable(conn, ff);
+
 	conn->time_gran = 1;
 	cfg->use_ino = 1;
 	if (ff->debug)
@@ -4842,6 +4894,459 @@ static int op_fallocate(const char *path EXT2FS_ATTR((unused)), int mode,
 }
 #endif /* SUPPORT_FALLOCATE */
 
+#ifdef HAVE_FUSE_IOMAP
+static void fuse2fs_iomap_hole(struct fuse2fs *ff, struct fuse_file_iomap *iomap,
+			       off_t pos, uint64_t count)
+{
+	iomap->dev = FUSE_IOMAP_DEV_NULL;
+	iomap->addr = FUSE_IOMAP_NULL_ADDR;
+	iomap->offset = pos;
+	iomap->length = count;
+	iomap->type = FUSE_IOMAP_TYPE_HOLE;
+}
+
+static void fuse2fs_iomap_hole_to_eof(struct fuse2fs *ff,
+				      struct fuse_file_iomap *iomap, off_t pos,
+				      off_t count,
+				      const struct ext2_inode_large *inode)
+{
+	ext2_filsys fs = ff->fs;
+	uint64_t isize = EXT2_I_SIZE(inode);
+
+	/*
+	 * We have to be careful about handling a hole to the right of the
+	 * entire mapping tree.  First, the mapping must start and end on a
+	 * block boundary because they must be aligned to at least an LBA for
+	 * the block layer; and to the fsblock for smoother operation.
+	 *
+	 * As for the length -- we could return a mapping all the way to
+	 * i_size, but i_size could be less than pos/count if we're zeroing the
+	 * EOF block in anticipation of a truncate operation.  Similarly, we
+	 * don't want to end the mapping at pos+count because we know there's
+	 * nothing mapped byeond here.
+	 */
+	uint64_t startoff = round_down(pos, fs->blocksize);
+	uint64_t eofoff = round_up(max(pos + count, isize), fs->blocksize);
+
+	dbg_printf(ff,
+ "pos=0x%llx count=0x%llx isize=0x%llx startoff=0x%llx eofoff=0x%llx\n",
+		   (unsigned long long)pos,
+		   (unsigned long long)count,
+		   (unsigned long long)isize,
+		   (unsigned long long)startoff,
+		   (unsigned long long)eofoff);
+
+	fuse2fs_iomap_hole(ff, iomap, startoff, eofoff - startoff);
+}
+
+#define DEBUG_IOMAP
+#ifdef DEBUG_IOMAP
+# define __DUMP_EXTENT(ff, func, tag, startoff, err, extent) \
+	do { \
+		dbg_printf((ff), \
+ "%s: %s startoff 0x%llx err %ld lblk 0x%llx pblk 0x%llx len 0x%x flags 0x%x\n", \
+			   (func), (tag), (startoff), (err), (extent)->e_lblk, \
+			   (extent)->e_pblk, (extent)->e_len, \
+			   (extent)->e_flags & EXT2_EXTENT_FLAGS_UNINIT); \
+	} while(0)
+# define DUMP_EXTENT(ff, tag, startoff, err, extent) \
+	__DUMP_EXTENT((ff), __func__, (tag), (startoff), (err), (extent))
+
+# define __DUMP_INFO(ff, func, tag, startoff, err, info) \
+	do { \
+		dbg_printf((ff), \
+ "%s: %s startoff 0x%llx err %ld entry %d/%d/%d level  %d/%d\n", \
+			   (func), (tag), (startoff), (err), \
+			   (info)->curr_entry, (info)->num_entries, \
+			   (info)->max_entries, (info)->curr_level, \
+			   (info)->max_depth); \
+	} while(0)
+# define DUMP_INFO(ff, tag, startoff, err, info) \
+	__DUMP_INFO((ff), __func__, (tag), (startoff), (err), (info))
+#else
+# define __DUMP_EXTENT(...)	((void)0)
+# define DUMP_EXTENT(...)	((void)0)
+# define DUMP_INFO(...)		((void)0)
+#endif
+
+static inline errcode_t __fuse2fs_get_mapping_at(struct fuse2fs *ff,
+						 ext2_extent_handle_t handle,
+						 blk64_t startoff,
+						 struct ext2fs_extent *bmap,
+						 const char *func)
+{
+	errcode_t err;
+
+	/*
+	 * Find the file mapping at startoff.  We don't check the return value
+	 * of _goto because _get will error out if _goto failed.  There's a
+	 * subtlety to the outcome of _goto when startoff falls in a sparse
+	 * hole however:
+	 *
+	 * Most of the time, _goto points the cursor at the mapping whose lblk
+	 * is just to the left of startoff.  The mapping may or may not overlap
+	 * startoff; this is ok.  In other words, the tree lookup behaves as if
+	 * we asked it to use a less than or equals comparison.
+	 *
+	 * However, if startoff is to the left of the first mapping in the
+	 * extent tree, _goto points the cursor at that first mapping because
+	 * it doesn't know how to deal with this situation.  In this case,
+	 * the tree lookup behaves as if we asked it to use a greater than
+	 * or equals comparison.
+	 *
+	 * Note: If _get() returns 'no current node', that means that there
+	 * aren't any mappings at all.
+	 */
+	ext2fs_extent_goto(handle, startoff);
+	err = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, bmap);
+	__DUMP_EXTENT(ff, func, "lookup", startoff, err, bmap);
+	if (err == EXT2_ET_NO_CURRENT_NODE)
+		err = EXT2_ET_EXTENT_NOT_FOUND;
+	return err;
+}
+
+static inline errcode_t __fuse2fs_get_next_mapping(struct fuse2fs *ff,
+						   ext2_extent_handle_t handle,
+						   blk64_t startoff,
+						   struct ext2fs_extent *bmap,
+						   const char *func)
+{
+	struct ext2fs_extent newex;
+	struct ext2_extent_info info;
+	errcode_t err;
+
+	/*
+	 * The extent tree code has this (probably broken) behavior that if
+	 * more than two of the highest levels of the cursor point at the
+	 * rightmost edge of an extent tree block, a _NEXT_LEAF movement fails
+	 * to move the cursor position of any of the lower levels.  IOWs, if
+	 * leaf level N is at the right edge, it will only advance level N-1
+	 * to the right.  If N-1 was at the right edge, the cursor resets to
+	 * record 0 of that level and goes down to the wrong leaf.
+	 *
+	 * Work around this by walking up (towards root level 0) the extent
+	 * tree until we find a level where we're not already at the rightmost
+	 * edge.  The _NEXT_LEAF movement will walk down the tree to find the
+	 * leaves.
+	 */
+	err = ext2fs_extent_get_info(handle, &info);
+	DUMP_INFO(ff, "UP?", startoff, err, &info);
+	if (err)
+		return err;
+
+	while (info.curr_entry == info.num_entries && info.curr_level > 0) {
+		err = ext2fs_extent_get(handle, EXT2_EXTENT_UP, &newex);
+		DUMP_EXTENT(ff, "UP", startoff, err, &newex);
+		if (err)
+			return err;
+		err = ext2fs_extent_get_info(handle, &info);
+		DUMP_INFO(ff, "UP", startoff, err, &info);
+		if (err)
+			return err;
+	}
+
+	/*
+	 * If we're at the root and there are no more entries, there's nothing
+	 * else to be found.
+	 */
+	if (info.curr_level == 0 && info.curr_entry == info.num_entries)
+		return EXT2_ET_EXTENT_NOT_FOUND;
+
+	/* Otherwise grab this next leaf and return it. */
+	err = ext2fs_extent_get(handle, EXT2_EXTENT_NEXT_LEAF, &newex);
+	DUMP_EXTENT(ff, "NEXT", startoff, err, &newex);
+	if (err)
+		return err;
+
+	*bmap = newex;
+	return 0;
+}
+
+#define fuse2fs_get_mapping_at(ff, handle, startoff, bmap) \
+	__fuse2fs_get_mapping_at((ff), (handle), (startoff), (bmap), __func__)
+#define fuse2fs_get_next_mapping(ff, handle, startoff, bmap) \
+	__fuse2fs_get_next_mapping((ff), (handle), (startoff), (bmap), __func__)
+
+static errcode_t fuse2fs_iomap_begin_extent(struct fuse2fs *ff, uint64_t ino,
+					    struct ext2_inode_large *inode,
+					    off_t pos, uint64_t count,
+					    uint32_t opflags,
+					    struct fuse_file_iomap *iomap)
+{
+	ext2_extent_handle_t handle;
+	struct ext2fs_extent extent = { };
+	ext2_filsys fs = ff->fs;
+	const blk64_t startoff = FUSE2FS_B_TO_FSBT(ff, pos);
+	errcode_t err;
+	int ret = 0;
+
+	err = ext2fs_extent_open2(fs, ino, EXT2_INODE(inode), &handle);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = fuse2fs_get_mapping_at(ff, handle, startoff, &extent);
+	if (err == EXT2_ET_EXTENT_NOT_FOUND) {
+		/* No mappings at all; the whole range is a hole. */
+		fuse2fs_iomap_hole_to_eof(ff, iomap, pos, count, inode);
+		goto out_handle;
+	}
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_handle;
+	}
+
+	if (startoff < extent.e_lblk) {
+		/*
+		 * Mapping starts to the right of the current position.
+		 * Synthesize a hole going to that next extent.
+		 */
+		fuse2fs_iomap_hole(ff, iomap, FUSE2FS_FSB_TO_B(ff, startoff),
+				FUSE2FS_FSB_TO_B(ff, extent.e_lblk - startoff));
+		goto out_handle;
+	}
+
+	if (startoff >= extent.e_lblk + extent.e_len) {
+		/*
+		 * Mapping ends to the left of the current position.  Try to
+		 * find the next mapping.  If there is no next mapping, the
+		 * whole range is in a hole.
+		 */
+		err = fuse2fs_get_next_mapping(ff, handle, startoff, &extent);
+		if (err == EXT2_ET_EXTENT_NOT_FOUND) {
+			fuse2fs_iomap_hole_to_eof(ff, iomap, pos, count, inode);
+			goto out_handle;
+		}
+
+		/*
+		 * If the new mapping starts to the right of startoff, there's
+		 * a hole from startoff to the start of the new mapping.
+		 */
+		if (startoff < extent.e_lblk) {
+			fuse2fs_iomap_hole(ff, iomap,
+				FUSE2FS_FSB_TO_B(ff, startoff),
+				FUSE2FS_FSB_TO_B(ff, extent.e_lblk - startoff));
+			goto out_handle;
+		}
+
+		/*
+		 * The new mapping starts at startoff.  Something weird
+		 * happened in the extent tree lookup, but we found a valid
+		 * mapping so we'll run with it.
+		 */
+	}
+
+	/* Mapping overlaps startoff, report this. */
+	iomap->dev = FUSE_IOMAP_DEV_NULL;
+	iomap->addr = FUSE2FS_FSB_TO_B(ff, extent.e_pblk);
+	iomap->offset = FUSE2FS_FSB_TO_B(ff, extent.e_lblk);
+	iomap->length = FUSE2FS_FSB_TO_B(ff, extent.e_len);
+	if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
+		iomap->type = FUSE_IOMAP_TYPE_UNWRITTEN;
+	else
+		iomap->type = FUSE_IOMAP_TYPE_MAPPED;
+
+out_handle:
+	ext2fs_extent_free(handle);
+	return ret;
+}
+
+static int fuse2fs_iomap_begin_indirect(struct fuse2fs *ff, uint64_t ino,
+					struct ext2_inode_large *inode,
+					off_t pos, uint64_t count,
+					uint32_t opflags,
+					struct fuse_file_iomap *iomap)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t startoff = FUSE2FS_B_TO_FSBT(ff, pos);
+	uint64_t isize = EXT2_I_SIZE(inode);
+	uint64_t real_count = min(count, 131072);
+	const blk64_t endoff = FUSE2FS_B_TO_FSB(ff, pos + real_count);
+	blk64_t startblock;
+	errcode_t err;
+
+	err = ext2fs_bmap2(fs, ino, EXT2_INODE(inode), NULL, 0, startoff, NULL,
+			   &startblock);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	iomap->dev = FUSE_IOMAP_DEV_NULL;
+	iomap->offset = FUSE2FS_FSB_TO_B(ff, startoff);
+	iomap->flags |= FUSE_IOMAP_F_MERGED;
+	if (startblock) {
+		iomap->addr = FUSE2FS_FSB_TO_B(ff, startblock);
+		iomap->type = FUSE_IOMAP_TYPE_MAPPED;
+	} else {
+		iomap->addr = FUSE_IOMAP_NULL_ADDR;
+		iomap->type = FUSE_IOMAP_TYPE_HOLE;
+	}
+	iomap->length = fs->blocksize;
+
+	/* See how long the mapping goes for. */
+	for (startoff++; startoff < endoff; startoff++) {
+		blk64_t prev_startblock = startblock;
+
+		err = ext2fs_bmap2(fs, ino, EXT2_INODE(inode), NULL, 0,
+				   startoff, NULL, &startblock);
+		if (err)
+			break;
+
+		if (iomap->type == FUSE_IOMAP_TYPE_MAPPED) {
+			if (startblock == prev_startblock + 1)
+				iomap->length += fs->blocksize;
+			else
+				break;
+		} else {
+			if (startblock == 0)
+				iomap->length += fs->blocksize;
+			else
+				break;
+		}
+	}
+
+	/*
+	 * If this is a hole that goes beyond EOF, report this as a hole to the
+	 * end of the range queried so that FIEMAP doesn't go mad.
+	 */
+	if (iomap->type == FUSE_IOMAP_TYPE_HOLE &&
+	    iomap->offset + iomap->length >= isize)
+		fuse2fs_iomap_hole_to_eof(ff, iomap, pos, count, inode);
+
+	return 0;
+}
+
+static int fuse2fs_iomap_begin_inline(struct fuse2fs *ff, ext2_ino_t ino,
+				      struct ext2_inode_large *inode, off_t pos,
+				      uint64_t count, struct fuse_file_iomap *iomap)
+{
+	uint64_t one_fsb = FUSE2FS_FSB_TO_B(ff, 1);
+
+	if (pos >= one_fsb) {
+		fuse2fs_iomap_hole_to_eof(ff, iomap, pos, count, inode);
+	} else {
+		/* ext4 only supports inline data files up to 1 fsb */
+		iomap->dev = FUSE_IOMAP_DEV_NULL;
+		iomap->addr = FUSE_IOMAP_NULL_ADDR;
+		iomap->offset = 0;
+		iomap->length = one_fsb;
+		iomap->type = FUSE_IOMAP_TYPE_INLINE;
+	}
+
+	return 0;
+}
+
+static int fuse2fs_iomap_begin_report(struct fuse2fs *ff, ext2_ino_t ino,
+				      struct ext2_inode_large *inode,
+				      off_t pos, uint64_t count,
+				      uint32_t opflags,
+				      struct fuse_file_iomap *read)
+{
+	if (inode->i_flags & EXT4_INLINE_DATA_FL)
+		return fuse2fs_iomap_begin_inline(ff, ino, inode, pos, count,
+						  read);
+
+	if (inode->i_flags & EXT4_EXTENTS_FL)
+		return fuse2fs_iomap_begin_extent(ff, ino, inode, pos, count,
+						  opflags, read);
+
+	return fuse2fs_iomap_begin_indirect(ff, ino, inode, pos, count,
+					    opflags, read);
+}
+
+static int fuse2fs_iomap_begin_read(struct fuse2fs *ff, ext2_ino_t ino,
+				    struct ext2_inode_large *inode, off_t pos,
+				    uint64_t count, uint32_t opflags,
+				    struct fuse_file_iomap *read)
+{
+	return -ENOSYS;
+}
+
+static int fuse2fs_iomap_begin_write(struct fuse2fs *ff, ext2_ino_t ino,
+				     struct ext2_inode_large *inode, off_t pos,
+				     uint64_t count, uint32_t opflags,
+				     struct fuse_file_iomap *read)
+{
+	return -ENOSYS;
+}
+
+static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
+			  off_t pos, uint64_t count, uint32_t opflags,
+			  struct fuse_file_iomap *read,
+			  struct fuse_file_iomap *write)
+{
+	struct fuse2fs *ff = fuse2fs_get();
+	struct ext2_inode_large inode;
+	ext2_filsys fs;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE2FS_CHECK_CONTEXT(ff);
+
+	dbg_printf(ff,
+ "%s: path=%s nodeid=%llu attr_ino=%llu pos=0x%llx count=0x%llx opflags=0x%x\n",
+		   __func__, path,
+		   (unsigned long long)nodeid,
+		   (unsigned long long)attr_ino,
+		   (unsigned long long)pos,
+		   (unsigned long long)count,
+		   opflags);
+
+	fs = fuse2fs_start(ff);
+	err = fuse2fs_read_inode(fs, attr_ino, &inode);
+	if (err) {
+		ret = translate_error(fs, attr_ino, err);
+		goto out_unlock;
+	}
+
+	if (opflags & FUSE_IOMAP_OP_REPORT)
+		ret = fuse2fs_iomap_begin_report(ff, attr_ino, &inode, pos,
+						 count, opflags, read);
+	else if (fuse_iomap_is_write(opflags))
+		ret = fuse2fs_iomap_begin_write(ff, attr_ino, &inode, pos,
+						count, opflags, read);
+	else
+		ret = fuse2fs_iomap_begin_read(ff, attr_ino, &inode, pos,
+					       count, opflags, read);
+	if (ret)
+		goto out_unlock;
+
+	dbg_printf(ff, "%s: nodeid=%llu attr_ino=%llu pos=0x%llx -> addr=0x%llx offset=0x%llx length=0x%llx type=%u\n",
+		   __func__,
+		   (unsigned long long)nodeid,
+		   (unsigned long long)attr_ino,
+		   (unsigned long long)pos,
+		   (unsigned long long)read->addr,
+		   (unsigned long long)read->offset,
+		   (unsigned long long)read->length,
+		   read->type);
+
+out_unlock:
+	fuse2fs_finish(ff, ret);
+	return ret;
+}
+
+static int op_iomap_end(const char *path, uint64_t nodeid, uint64_t attr_ino,
+			off_t pos, uint64_t count, uint32_t opflags,
+			ssize_t written, const struct fuse_file_iomap *iomap)
+{
+	struct fuse2fs *ff = fuse2fs_get();
+
+	FUSE2FS_CHECK_CONTEXT(ff);
+
+	dbg_printf(ff,
+ "%s: path=%s nodeid=%llu attr_ino=%llu pos=0x%llx count=0x%llx opflags=0x%x written=0x%zx mapflags=0x%x\n",
+		   __func__, path,
+		   (unsigned long long)nodeid,
+		   (unsigned long long)attr_ino,
+		   (unsigned long long)pos,
+		   (unsigned long long)count,
+		   opflags,
+		   written,
+		   iomap->flags);
+
+	return 0;
+}
+#endif /* HAVE_FUSE_IOMAP */
+
 static struct fuse_operations fs_ops = {
 	.init = op_init,
 	.destroy = op_destroy,
@@ -4883,6 +5388,10 @@ static struct fuse_operations fs_ops = {
 #ifdef SUPPORT_FALLOCATE
 	.fallocate = op_fallocate,
 #endif
+#ifdef HAVE_FUSE_IOMAP
+	.iomap_begin = op_iomap_begin,
+	.iomap_end = op_iomap_end,
+#endif /* HAVE_FUSE_IOMAP */
 };
 
 static int get_random_bytes(void *p, size_t sz)
@@ -5106,17 +5615,19 @@ static void fuse2fs_com_err_proc(const char *whoami, errcode_t code,
 int main(int argc, char *argv[])
 {
 	struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
-	struct fuse2fs fctx;
+	struct fuse2fs fctx = {
+		.magic = FUSE2FS_MAGIC,
+		.opstate = F2OP_WRITABLE,
+		.logfd = -1,
+#ifdef HAVE_FUSE_IOMAP
+		.iomap_state = IOMAP_UNKNOWN,
+#endif
+	};
 	errcode_t err;
 	FILE *orig_stderr = stderr;
 	char extra_args[BUFSIZ];
 	int ret;
 
-	memset(&fctx, 0, sizeof(fctx));
-	fctx.magic = FUSE2FS_MAGIC;
-	fctx.logfd = -1;
-	fctx.opstate = F2OP_WRITABLE;
-
 	ret = fuse_opt_parse(&args, &fctx, fuse2fs_opts, fuse2fs_opt_proc);
 	if (ret)
 		exit(1);

[PATCH 02/17] fuse2fs: add iomap= mount option

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add a mount option to control iomap usage so that we can test before and
after scenarios.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.1.in |    6 ++++++
 fuse4fs/fuse4fs.c    |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 misc/fuse2fs.1.in    |    6 ++++++
 misc/fuse2fs.c       |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 104 insertions(+)


diff --git a/fuse4fs/fuse4fs.1.in b/fuse4fs/fuse4fs.1.in
index 8bef5f48802385..8855867d27101d 100644
--- a/fuse4fs/fuse4fs.1.in
+++ b/fuse4fs/fuse4fs.1.in
@@ -75,6 +75,12 @@ .SS "fuse4fs options:"
 \fB-o\fR fuse4fs_debug
 enable fuse4fs debugging
 .TP
+\fB-o\fR iomap=
+If set to \fI1\fR, requires iomap to be enabled.
+If set to \fI0\fR, forbids use of iomap.
+If set to \fIdefault\fR (or not set), enables iomap if present.
+This substantially improves the performance of the fuse4fs server.
+.TP
 \fB-o\fR kernel
 Behave more like the kernel ext4 driver in the following ways:
 Allows processes owned by other users to access the filesystem.
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index bf9c2081702132..2d7b40911ce0f7 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -223,6 +223,12 @@ enum fuse4fs_opstate {
 	F4OP_SHUTDOWN,
 };
 
+enum fuse4fs_feature_toggle {
+	FT_DISABLE,
+	FT_ENABLE,
+	FT_DEFAULT,
+};
+
 #ifdef HAVE_FUSE_IOMAP
 enum fuse4fs_iomap_state {
 	IOMAP_DISABLED,
@@ -260,6 +266,7 @@ struct fuse4fs {
 	int logfd;
 	int blocklog;
 #ifdef HAVE_FUSE_IOMAP
+	enum fuse4fs_feature_toggle iomap_want;
 	enum fuse4fs_iomap_state iomap_state;
 #endif
 	unsigned int blockmask;
@@ -1539,6 +1546,12 @@ static void fuse4fs_iomap_enable(struct fuse_conn_info *conn,
 
 	if (ff->iomap_state == IOMAP_UNKNOWN)
 		ff->iomap_state = IOMAP_DISABLED;
+
+	if (!fuse4fs_iomap_enabled(ff)) {
+		if (ff->iomap_want == FT_ENABLE)
+			err_printf(ff, "%s\n", _("Could not enable iomap."));
+		return;
+	}
 }
 #else
 # define fuse4fs_iomap_enable(...)	((void)0)
@@ -5981,6 +5994,9 @@ enum {
 	FUSE4FS_CACHE_SIZE,
 	FUSE4FS_DIRSYNC,
 	FUSE4FS_ERRORS_BEHAVIOR,
+#ifdef HAVE_FUSE_IOMAP
+	FUSE4FS_IOMAP,
+#endif
 };
 
 #define FUSE4FS_OPT(t, p, v) { t, offsetof(struct fuse4fs, p), v }
@@ -6012,6 +6028,10 @@ static struct fuse_opt fuse4fs_opts[] = {
 	FUSE_OPT_KEY("cache_size=%s",	FUSE4FS_CACHE_SIZE),
 	FUSE_OPT_KEY("dirsync",		FUSE4FS_DIRSYNC),
 	FUSE_OPT_KEY("errors=%s",	FUSE4FS_ERRORS_BEHAVIOR),
+#ifdef HAVE_FUSE_IOMAP
+	FUSE_OPT_KEY("iomap=%s",	FUSE4FS_IOMAP),
+	FUSE_OPT_KEY("iomap",		FUSE4FS_IOMAP),
+#endif
 
 	FUSE_OPT_KEY("-V",             FUSE4FS_VERSION),
 	FUSE_OPT_KEY("--version",      FUSE4FS_VERSION),
@@ -6063,6 +6083,23 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
 
 		/* do not pass through to libfuse */
 		return 0;
+#ifdef HAVE_FUSE_IOMAP
+	case FUSE4FS_IOMAP:
+		if (strcmp(arg, "iomap") == 0 || strcmp(arg + 6, "1") == 0)
+			ff->iomap_want = FT_ENABLE;
+		else if (strcmp(arg + 6, "0") == 0)
+			ff->iomap_want = FT_DISABLE;
+		else if (strcmp(arg + 6, "default") == 0)
+			ff->iomap_want = FT_DEFAULT;
+		else {
+			fprintf(stderr, "%s: %s\n", arg,
+ _("unknown iomap= behavior."));
+			return -1;
+		}
+
+		/* do not pass through to libfuse */
+		return 0;
+#endif
 	case FUSE4FS_IGNORED:
 		return 0;
 	case FUSE4FS_HELP:
@@ -6090,6 +6127,9 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
 	"    -o cache_size=N[KMG]   use a disk cache of this size\n"
 	"    -o errors=             behavior when an error is encountered:\n"
 	"                           continue|remount-ro|panic\n"
+#ifdef HAVE_FUSE_IOMAP
+	"    -o iomap=              0 to disable iomap, 1 to enable iomap\n"
+#endif
 	"\n",
 			outargs->argv[0]);
 		if (key == FUSE4FS_HELPFULL) {
@@ -6282,6 +6322,7 @@ int main(int argc, char *argv[])
 		.opstate = F4OP_WRITABLE,
 		.logfd = -1,
 #ifdef HAVE_FUSE_IOMAP
+		.iomap_want = FT_DEFAULT,
 		.iomap_state = IOMAP_UNKNOWN,
 #endif
 	};
@@ -6299,6 +6340,11 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 
+#ifdef HAVE_FUSE_IOMAP
+	if (fctx.iomap_want == FT_DISABLE)
+		fctx.iomap_state = IOMAP_DISABLED;
+#endif
+
 	/* /dev/sda -> sda for reporting */
 	fctx.shortdev = strrchr(fctx.device, '/');
 	if (fctx.shortdev)
diff --git a/misc/fuse2fs.1.in b/misc/fuse2fs.1.in
index 6acfa092851292..2b55fa0e723966 100644
--- a/misc/fuse2fs.1.in
+++ b/misc/fuse2fs.1.in
@@ -75,6 +75,12 @@ .SS "fuse2fs options:"
 \fB-o\fR fuse2fs_debug
 enable fuse2fs debugging
 .TP
+\fB-o\fR iomap=
+If set to \fI1\fR, requires iomap to be enabled.
+If set to \fI0\fR, forbids use of iomap.
+If set to \fIdefault\fR (or not set), enables iomap if present.
+This substantially improves the performance of the fuse2fs server.
+.TP
 \fB-o\fR kernel
 Behave more like the kernel ext4 driver in the following ways:
 Allows processes owned by other users to access the filesystem.
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index ca61fbc89f5fda..95d3dedbdb8b80 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -216,6 +216,12 @@ enum fuse2fs_opstate {
 	F2OP_SHUTDOWN,
 };
 
+enum fuse2fs_feature_toggle {
+	FT_DISABLE,
+	FT_ENABLE,
+	FT_DEFAULT,
+};
+
 #ifdef HAVE_FUSE_IOMAP
 enum fuse2fs_iomap_state {
 	IOMAP_DISABLED,
@@ -253,6 +259,7 @@ struct fuse2fs {
 	int logfd;
 	int blocklog;
 #ifdef HAVE_FUSE_IOMAP
+	enum fuse2fs_feature_toggle iomap_want;
 	enum fuse2fs_iomap_state iomap_state;
 #endif
 	unsigned int blockmask;
@@ -1345,6 +1352,12 @@ static void fuse2fs_iomap_enable(struct fuse_conn_info *conn,
 
 	if (ff->iomap_state == IOMAP_UNKNOWN)
 		ff->iomap_state = IOMAP_DISABLED;
+
+	if (!fuse2fs_iomap_enabled(ff)) {
+		if (ff->iomap_want == FT_ENABLE)
+			err_printf(ff, "%s\n", _("Could not enable iomap."));
+		return;
+	}
 }
 #else
 # define fuse2fs_iomap_enable(...)	((void)0)
@@ -5419,6 +5432,9 @@ enum {
 	FUSE2FS_CACHE_SIZE,
 	FUSE2FS_DIRSYNC,
 	FUSE2FS_ERRORS_BEHAVIOR,
+#ifdef HAVE_FUSE_IOMAP
+	FUSE2FS_IOMAP,
+#endif
 };
 
 #define FUSE2FS_OPT(t, p, v) { t, offsetof(struct fuse2fs, p), v }
@@ -5450,6 +5466,10 @@ static struct fuse_opt fuse2fs_opts[] = {
 	FUSE_OPT_KEY("cache_size=%s",	FUSE2FS_CACHE_SIZE),
 	FUSE_OPT_KEY("dirsync",		FUSE2FS_DIRSYNC),
 	FUSE_OPT_KEY("errors=%s",	FUSE2FS_ERRORS_BEHAVIOR),
+#ifdef HAVE_FUSE_IOMAP
+	FUSE_OPT_KEY("iomap=%s",	FUSE2FS_IOMAP),
+	FUSE_OPT_KEY("iomap",		FUSE2FS_IOMAP),
+#endif
 
 	FUSE_OPT_KEY("-V",             FUSE2FS_VERSION),
 	FUSE_OPT_KEY("--version",      FUSE2FS_VERSION),
@@ -5501,6 +5521,23 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
 
 		/* do not pass through to libfuse */
 		return 0;
+#ifdef HAVE_FUSE_IOMAP
+	case FUSE2FS_IOMAP:
+		if (strcmp(arg, "iomap") == 0 || strcmp(arg + 6, "1") == 0)
+			ff->iomap_want = FT_ENABLE;
+		else if (strcmp(arg + 6, "0") == 0)
+			ff->iomap_want = FT_DISABLE;
+		else if (strcmp(arg + 6, "default") == 0)
+			ff->iomap_want = FT_DEFAULT;
+		else {
+			fprintf(stderr, "%s: %s\n", arg,
+ _("unknown iomap= behavior."));
+			return -1;
+		}
+
+		/* do not pass through to libfuse */
+		return 0;
+#endif
 	case FUSE2FS_IGNORED:
 		return 0;
 	case FUSE2FS_HELP:
@@ -5528,6 +5565,9 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
 	"    -o cache_size=N[KMG]   use a disk cache of this size\n"
 	"    -o errors=             behavior when an error is encountered:\n"
 	"                           continue|remount-ro|panic\n"
+#ifdef HAVE_FUSE_IOMAP
+	"    -o iomap=              0 to disable iomap, 1 to enable iomap\n"
+#endif
 	"\n",
 			outargs->argv[0]);
 		if (key == FUSE2FS_HELPFULL) {
@@ -5620,6 +5660,7 @@ int main(int argc, char *argv[])
 		.opstate = F2OP_WRITABLE,
 		.logfd = -1,
 #ifdef HAVE_FUSE_IOMAP
+		.iomap_want = FT_DEFAULT,
 		.iomap_state = IOMAP_UNKNOWN,
 #endif
 	};
@@ -5637,6 +5678,11 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 
+#ifdef HAVE_FUSE_IOMAP
+	if (fctx.iomap_want == FT_DISABLE)
+		fctx.iomap_state = IOMAP_DISABLED;
+#endif
+
 	/* /dev/sda -> sda for reporting */
 	fctx.shortdev = strrchr(fctx.device, '/');
 	if (fctx.shortdev)

[PATCH 03/17] fuse2fs: implement iomap configuration

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Upload the filesystem geometry to the kernel when asked.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   96 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 misc/fuse2fs.c    |   96 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 186 insertions(+), 6 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 2d7b40911ce0f7..66683a416749d8 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -196,6 +196,10 @@ static inline uint64_t round_down(uint64_t b, unsigned int align)
 # define FL_ZERO_RANGE_FLAG (0)
 #endif
 
+#ifndef NSEC_PER_SEC
+# define NSEC_PER_SEC	(1000000000L)
+#endif
+
 errcode_t ext2fs_run_ext3_journal(ext2_filsys *fs);
 
 const char *err_shortdev;
@@ -813,9 +817,9 @@ static int update_atime(ext2_filsys fs, ext2_ino_t ino)
 	EXT4_INODE_GET_XTIME(i_mtime, &mtime, pinode);
 	get_now(&now);
 
-	datime = atime.tv_sec + ((double)atime.tv_nsec / 1000000000);
-	dmtime = mtime.tv_sec + ((double)mtime.tv_nsec / 1000000000);
-	dnow = now.tv_sec + ((double)now.tv_nsec / 1000000000);
+	datime = atime.tv_sec + ((double)atime.tv_nsec / NSEC_PER_SEC);
+	dmtime = mtime.tv_sec + ((double)mtime.tv_nsec / NSEC_PER_SEC);
+	dnow = now.tv_sec + ((double)now.tv_nsec / NSEC_PER_SEC);
 
 	/*
 	 * If atime is newer than mtime and atime hasn't been updated in thirty
@@ -5918,6 +5922,91 @@ static void op_iomap_end(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 
 	fuse_reply_err(req, 0);
 }
+
+/*
+ * Maximal extent format file size.
+ * Resulting logical blkno at s_maxbytes must fit in our on-disk
+ * extent format containers, within a sector_t, and within i_blocks
+ * in the vfs.  ext4 inode has 48 bits of i_block in fsblock units,
+ * so that won't be a limiting factor.
+ *
+ * However there is other limiting factor. We do store extents in the form
+ * of starting block and length, hence the resulting length of the extent
+ * covering maximum file size must fit into on-disk format containers as
+ * well. Given that length is always by 1 unit bigger than max unit (because
+ * we count 0 as well) we have to lower the s_maxbytes by one fs block.
+ *
+ * Note, this does *not* consider any metadata overhead for vfs i_blocks.
+ */
+static off_t fuse4fs_max_size(struct fuse4fs *ff, off_t upper_limit)
+{
+	off_t res;
+
+	if (!ext2fs_has_feature_huge_file(ff->fs->super)) {
+		upper_limit = (1LL << 32) - 1;
+
+		/* total blocks in file system block size */
+		upper_limit >>= (ff->blocklog - 9);
+		upper_limit <<= ff->blocklog;
+	}
+
+	/*
+	 * 32-bit extent-start container, ee_block. We lower the maxbytes
+	 * by one fs block, so ee_len can cover the extent of maximum file
+	 * size
+	 */
+	res = (1LL << 32) - 1;
+	res <<= ff->blocklog;
+
+	/* Sanity check against vm- & vfs- imposed limits */
+	if (res > upper_limit)
+		res = upper_limit;
+
+	return res;
+}
+
+static void op_iomap_config(fuse_req_t req, uint64_t flags, uint64_t maxbytes)
+{
+	struct fuse_iomap_config cfg = { };
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_filsys fs;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+
+	dbg_printf(ff, "%s: flags=0x%llx maxbytes=0x%llx\n", __func__,
+		   (unsigned long long)flags,
+		   (unsigned long long)maxbytes);
+	fs = fuse4fs_start(ff);
+
+	cfg.flags |= FUSE_IOMAP_CONFIG_UUID;
+	memcpy(cfg.s_uuid, fs->super->s_uuid, sizeof(cfg.s_uuid));
+	cfg.s_uuid_len = sizeof(fs->super->s_uuid);
+
+	cfg.flags |= FUSE_IOMAP_CONFIG_BLOCKSIZE;
+	cfg.s_blocksize = FUSE4FS_FSB_TO_B(ff, 1);
+
+	/*
+	 * If there inode is large enough to house i_[acm]time_extra then we
+	 * can turn on nanosecond timestamps; i_crtime was the next field added
+	 * after i_atime_extra.
+	 */
+	cfg.flags |= FUSE_IOMAP_CONFIG_TIME;
+	if (fs->super->s_inode_size >=
+	    offsetof(struct ext2_inode_large, i_crtime)) {
+		cfg.s_time_gran = 1;
+		cfg.s_time_max = EXT4_EXTRA_TIMESTAMP_MAX;
+	} else {
+		cfg.s_time_gran = NSEC_PER_SEC;
+		cfg.s_time_max = EXT4_NON_EXTRA_TIMESTAMP_MAX;
+	}
+	cfg.s_time_min = EXT4_TIMESTAMP_MIN;
+
+	cfg.flags |= FUSE_IOMAP_CONFIG_MAXBYTES;
+	cfg.s_maxbytes = fuse4fs_max_size(ff, maxbytes);
+
+	fuse4fs_finish(ff, 0);
+	fuse_reply_iomap_config(req, &cfg);
+}
 #endif /* HAVE_FUSE_IOMAP */
 
 static struct fuse_lowlevel_ops fs_ops = {
@@ -5966,6 +6055,7 @@ static struct fuse_lowlevel_ops fs_ops = {
 #ifdef HAVE_FUSE_IOMAP
 	.iomap_begin = op_iomap_begin,
 	.iomap_end = op_iomap_end,
+	.iomap_config = op_iomap_config,
 #endif /* HAVE_FUSE_IOMAP */
 };
 
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 95d3dedbdb8b80..5b5a0934062b64 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -190,6 +190,10 @@ static inline uint64_t round_down(uint64_t b, unsigned int align)
 # define FL_ZERO_RANGE_FLAG (0)
 #endif
 
+#ifndef NSEC_PER_SEC
+# define NSEC_PER_SEC	(1000000000L)
+#endif
+
 errcode_t ext2fs_run_ext3_journal(ext2_filsys *fs);
 
 const char *err_shortdev;
@@ -649,9 +653,9 @@ static int update_atime(ext2_filsys fs, ext2_ino_t ino)
 	EXT4_INODE_GET_XTIME(i_mtime, &mtime, pinode);
 	get_now(&now);
 
-	datime = atime.tv_sec + ((double)atime.tv_nsec / 1000000000);
-	dmtime = mtime.tv_sec + ((double)mtime.tv_nsec / 1000000000);
-	dnow = now.tv_sec + ((double)now.tv_nsec / 1000000000);
+	datime = atime.tv_sec + ((double)atime.tv_nsec / NSEC_PER_SEC);
+	dmtime = mtime.tv_sec + ((double)mtime.tv_nsec / NSEC_PER_SEC);
+	dnow = now.tv_sec + ((double)now.tv_nsec / NSEC_PER_SEC);
 
 	/*
 	 * If atime is newer than mtime and atime hasn't been updated in thirty
@@ -5358,6 +5362,91 @@ static int op_iomap_end(const char *path, uint64_t nodeid, uint64_t attr_ino,
 
 	return 0;
 }
+
+/*
+ * Maximal extent format file size.
+ * Resulting logical blkno at s_maxbytes must fit in our on-disk
+ * extent format containers, within a sector_t, and within i_blocks
+ * in the vfs.  ext4 inode has 48 bits of i_block in fsblock units,
+ * so that won't be a limiting factor.
+ *
+ * However there is other limiting factor. We do store extents in the form
+ * of starting block and length, hence the resulting length of the extent
+ * covering maximum file size must fit into on-disk format containers as
+ * well. Given that length is always by 1 unit bigger than max unit (because
+ * we count 0 as well) we have to lower the s_maxbytes by one fs block.
+ *
+ * Note, this does *not* consider any metadata overhead for vfs i_blocks.
+ */
+static off_t fuse2fs_max_size(struct fuse2fs *ff, off_t upper_limit)
+{
+	off_t res;
+
+	if (!ext2fs_has_feature_huge_file(ff->fs->super)) {
+		upper_limit = (1LL << 32) - 1;
+
+		/* total blocks in file system block size */
+		upper_limit >>= (ff->blocklog - 9);
+		upper_limit <<= ff->blocklog;
+	}
+
+	/*
+	 * 32-bit extent-start container, ee_block. We lower the maxbytes
+	 * by one fs block, so ee_len can cover the extent of maximum file
+	 * size
+	 */
+	res = (1LL << 32) - 1;
+	res <<= ff->blocklog;
+
+	/* Sanity check against vm- & vfs- imposed limits */
+	if (res > upper_limit)
+		res = upper_limit;
+
+	return res;
+}
+
+static int op_iomap_config(uint64_t flags, off_t maxbytes,
+			   struct fuse_iomap_config *cfg)
+{
+	struct fuse2fs *ff = fuse2fs_get();
+	ext2_filsys fs;
+
+	FUSE2FS_CHECK_CONTEXT(ff);
+
+	dbg_printf(ff, "%s: flags=0x%llx maxbytes=0x%llx\n", __func__,
+		   (unsigned long long)flags,
+		   (unsigned long long)maxbytes);
+	fs = fuse2fs_start(ff);
+
+	cfg->flags |= FUSE_IOMAP_CONFIG_UUID;
+	memcpy(cfg->s_uuid, fs->super->s_uuid, sizeof(cfg->s_uuid));
+	cfg->s_uuid_len = sizeof(fs->super->s_uuid);
+
+	cfg->flags |= FUSE_IOMAP_CONFIG_BLOCKSIZE;
+	cfg->s_blocksize = FUSE2FS_FSB_TO_B(ff, 1);
+
+	/*
+	 * If there inode is large enough to house i_[acm]time_extra then we
+	 * can turn on nanosecond timestamps; i_crtime was the next field added
+	 * after i_atime_extra.
+	 */
+	cfg->flags |= FUSE_IOMAP_CONFIG_TIME;
+	if (fs->super->s_inode_size >=
+	    offsetof(struct ext2_inode_large, i_crtime)) {
+		cfg->s_time_gran = 1;
+		cfg->s_time_max = EXT4_EXTRA_TIMESTAMP_MAX;
+	} else {
+		cfg->s_time_gran = NSEC_PER_SEC;
+		cfg->s_time_max = EXT4_NON_EXTRA_TIMESTAMP_MAX;
+	}
+	cfg->s_time_min = EXT4_TIMESTAMP_MIN;
+
+	cfg->flags |= FUSE_IOMAP_CONFIG_MAXBYTES;
+	cfg->s_maxbytes = fuse2fs_max_size(ff, maxbytes);
+
+	fuse2fs_finish(ff, 0);
+	return 0;
+}
 #endif /* HAVE_FUSE_IOMAP */
 
 static struct fuse_operations fs_ops = {
@@ -5404,6 +5493,7 @@ static struct fuse_operations fs_ops = {
 #ifdef HAVE_FUSE_IOMAP
 	.iomap_begin = op_iomap_begin,
 	.iomap_end = op_iomap_end,
+	.iomap_config = op_iomap_config,
 #endif /* HAVE_FUSE_IOMAP */
 };
 

[PATCH 04/17] fuse2fs: register block devices for use with iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Register the ext4 block device with the kernel for use with iomap.  For
now this is redundant with using fuseblk mode because the kernel
automatically registers any fuseblk devices, but eventually we'll go
back to regular fuse mode and we'll have to pin the bdev ourselves.
In theory this interface supports strange beasts where the metadata can
exist somewhere else entirely (or be made up by AI) while the file data
persists to real disks.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   44 ++++++++++++++++++++++++++++++++++++++++----
 misc/fuse2fs.c    |   42 ++++++++++++++++++++++++++++++++++++++----
 2 files changed, 78 insertions(+), 8 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 66683a416749d8..958427efef04b7 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -272,6 +272,7 @@ struct fuse4fs {
 #ifdef HAVE_FUSE_IOMAP
 	enum fuse4fs_feature_toggle iomap_want;
 	enum fuse4fs_iomap_state iomap_state;
+	uint32_t iomap_dev;
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -5712,7 +5713,7 @@ static errcode_t fuse4fs_iomap_begin_extent(struct fuse4fs *ff, uint64_t ino,
 	}
 
 	/* Mapping overlaps startoff, report this. */
-	iomap->dev = FUSE_IOMAP_DEV_NULL;
+	iomap->dev = ff->iomap_dev;
 	iomap->addr = FUSE4FS_FSB_TO_B(ff, extent.e_pblk);
 	iomap->offset = FUSE4FS_FSB_TO_B(ff, extent.e_lblk);
 	iomap->length = FUSE4FS_FSB_TO_B(ff, extent.e_len);
@@ -5745,13 +5746,14 @@ static int fuse4fs_iomap_begin_indirect(struct fuse4fs *ff, uint64_t ino,
 	if (err)
 		return translate_error(fs, ino, err);
 
-	iomap->dev = FUSE_IOMAP_DEV_NULL;
 	iomap->offset = FUSE4FS_FSB_TO_B(ff, startoff);
 	iomap->flags |= FUSE_IOMAP_F_MERGED;
 	if (startblock) {
+		iomap->dev = ff->iomap_dev;
 		iomap->addr = FUSE4FS_FSB_TO_B(ff, startblock);
 		iomap->type = FUSE_IOMAP_TYPE_MAPPED;
 	} else {
+		iomap->dev = FUSE_IOMAP_DEV_NULL;
 		iomap->addr = FUSE_IOMAP_NULL_ADDR;
 		iomap->type = FUSE_IOMAP_TYPE_HOLE;
 	}
@@ -5965,11 +5967,36 @@ static off_t fuse4fs_max_size(struct fuse4fs *ff, off_t upper_limit)
 	return res;
 }
 
+static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)
+{
+	errcode_t err;
+	int fd;
+	int ret;
+
+	err = io_channel_get_fd(ff->fs->io, &fd);
+	if (err)
+		return translate_error(ff->fs, 0, err);
+
+	ret = fuse_lowlevel_iomap_device_add(ff->fuse, fd, 0);
+	if (ret < 0) {
+		dbg_printf(ff, "%s: cannot register iomap dev fd=%d, err=%d\n",
+			   __func__, fd, -ret);
+		return translate_error(ff->fs, 0, -ret);
+	}
+
+	dbg_printf(ff, "%s: registered iomap dev fd=%d iomap_dev=%u\n",
+		   __func__, fd, ff->iomap_dev);
+
+	ff->iomap_dev = ret;
+	return 0;
+}
+
 static void op_iomap_config(fuse_req_t req, uint64_t flags, uint64_t maxbytes)
 {
 	struct fuse_iomap_config cfg = { };
 	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_filsys fs;
+	int ret = 0;
 
 	FUSE4FS_CHECK_CONTEXT(req);
 
@@ -6004,8 +6031,16 @@ static void op_iomap_config(fuse_req_t req, uint64_t flags, uint64_t maxbytes)
 	cfg.flags |= FUSE_IOMAP_CONFIG_MAXBYTES;
 	cfg.s_maxbytes = fuse4fs_max_size(ff, maxbytes);
 
-	fuse4fs_finish(ff, 0);
-	fuse_reply_iomap_config(req, &cfg);
+	ret = fuse4fs_iomap_config_devices(ff);
+	if (ret)
+		goto out_unlock;
+
+out_unlock:
+	fuse4fs_finish(ff, ret);
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_iomap_config(req, &cfg);
 }
 #endif /* HAVE_FUSE_IOMAP */
 
@@ -6414,6 +6449,7 @@ int main(int argc, char *argv[])
 #ifdef HAVE_FUSE_IOMAP
 		.iomap_want = FT_DEFAULT,
 		.iomap_state = IOMAP_UNKNOWN,
+		.iomap_dev = FUSE_IOMAP_DEV_NULL,
 #endif
 	};
 	errcode_t err;
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 5b5a0934062b64..adaa25718ddaaf 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -41,6 +41,7 @@
 # define _FILE_OFFSET_BITS 64
 #endif /* _FILE_OFFSET_BITS */
 #include <fuse.h>
+#include <fuse_lowlevel.h>
 #ifdef __SET_FOB_FOR_FUSE
 # undef _FILE_OFFSET_BITS
 #endif /* __SET_FOB_FOR_FUSE */
@@ -265,6 +266,7 @@ struct fuse2fs {
 #ifdef HAVE_FUSE_IOMAP
 	enum fuse2fs_feature_toggle iomap_want;
 	enum fuse2fs_iomap_state iomap_state;
+	uint32_t iomap_dev;
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -5153,7 +5155,7 @@ static errcode_t fuse2fs_iomap_begin_extent(struct fuse2fs *ff, uint64_t ino,
 	}
 
 	/* Mapping overlaps startoff, report this. */
-	iomap->dev = FUSE_IOMAP_DEV_NULL;
+	iomap->dev = ff->iomap_dev;
 	iomap->addr = FUSE2FS_FSB_TO_B(ff, extent.e_pblk);
 	iomap->offset = FUSE2FS_FSB_TO_B(ff, extent.e_lblk);
 	iomap->length = FUSE2FS_FSB_TO_B(ff, extent.e_len);
@@ -5186,13 +5188,14 @@ static int fuse2fs_iomap_begin_indirect(struct fuse2fs *ff, uint64_t ino,
 	if (err)
 		return translate_error(fs, ino, err);
 
-	iomap->dev = FUSE_IOMAP_DEV_NULL;
 	iomap->offset = FUSE2FS_FSB_TO_B(ff, startoff);
 	iomap->flags |= FUSE_IOMAP_F_MERGED;
 	if (startblock) {
+		iomap->dev = ff->iomap_dev;
 		iomap->addr = FUSE2FS_FSB_TO_B(ff, startblock);
 		iomap->type = FUSE_IOMAP_TYPE_MAPPED;
 	} else {
+		iomap->dev = FUSE_IOMAP_DEV_NULL;
 		iomap->addr = FUSE_IOMAP_NULL_ADDR;
 		iomap->type = FUSE_IOMAP_TYPE_HOLE;
 	}
@@ -5405,11 +5408,36 @@ static off_t fuse2fs_max_size(struct fuse2fs *ff, off_t upper_limit)
 	return res;
 }
 
+static int fuse2fs_iomap_config_devices(struct fuse2fs *ff)
+{
+	errcode_t err;
+	int fd;
+	int ret;
+
+	err = io_channel_get_fd(ff->fs->io, &fd);
+	if (err)
+		return translate_error(ff->fs, 0, err);
+
+	ret = fuse_fs_iomap_device_add(fd, 0);
+	if (ret < 0) {
+		dbg_printf(ff, "%s: cannot register iomap dev fd=%d, err=%d\n",
+			   __func__, fd, -ret);
+		return translate_error(ff->fs, 0, -ret);
+	}
+
+	dbg_printf(ff, "%s: registered iomap dev fd=%d iomap_dev=%u\n",
+		   __func__, fd, ff->iomap_dev);
+
+	ff->iomap_dev = ret;
+	return 0;
+}
+
 static int op_iomap_config(uint64_t flags, off_t maxbytes,
 			   struct fuse_iomap_config *cfg)
 {
 	struct fuse2fs *ff = fuse2fs_get();
 	ext2_filsys fs;
+	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
 
@@ -5444,8 +5472,13 @@ static int op_iomap_config(uint64_t flags, off_t maxbytes,
 	cfg->flags |= FUSE_IOMAP_CONFIG_MAXBYTES;
 	cfg->s_maxbytes = fuse2fs_max_size(ff, maxbytes);
 
-	fuse2fs_finish(ff, 0);
-	return 0;
+	ret = fuse2fs_iomap_config_devices(ff);
+	if (ret)
+		goto out_unlock;
+
+out_unlock:
+	fuse2fs_finish(ff, ret);
+	return ret;
 }
 #endif /* HAVE_FUSE_IOMAP */
 
@@ -5752,6 +5785,7 @@ int main(int argc, char *argv[])
 #ifdef HAVE_FUSE_IOMAP
 		.iomap_want = FT_DEFAULT,
 		.iomap_state = IOMAP_UNKNOWN,
+		.iomap_dev = FUSE_IOMAP_DEV_NULL,
 #endif
 	};
 	errcode_t err;

[PATCH 05/17] fuse2fs: implement directio file reads

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Implement file reads via iomap.  Currently only directio is supported.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   14 +++++++++++++-
 misc/fuse2fs.c    |   14 +++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 958427efef04b7..90d94bb7404f90 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -5835,7 +5835,19 @@ static int fuse4fs_iomap_begin_read(struct fuse4fs *ff, ext2_ino_t ino,
 				    uint64_t count, uint32_t opflags,
 				    struct fuse_file_iomap *read)
 {
-	return -ENOSYS;
+	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
+		return -ENOSYS;
+
+	/* fall back to slow path for inline data reads */
+	if (inode->i_flags & EXT4_INLINE_DATA_FL)
+		return -ENOSYS;
+
+	if (inode->i_flags & EXT4_EXTENTS_FL)
+		return fuse4fs_iomap_begin_extent(ff, ino, inode, pos, count,
+						  opflags, read);
+
+	return fuse4fs_iomap_begin_indirect(ff, ino, inode, pos, count,
+					    opflags, read);
 }
 
 static int fuse4fs_iomap_begin_write(struct fuse4fs *ff, ext2_ino_t ino,
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index adaa25718ddaaf..31fd882dac4ef6 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -5277,7 +5277,19 @@ static int fuse2fs_iomap_begin_read(struct fuse2fs *ff, ext2_ino_t ino,
 				    uint64_t count, uint32_t opflags,
 				    struct fuse_file_iomap *read)
 {
-	return -ENOSYS;
+	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
+		return -ENOSYS;
+
+	/* fall back to slow path for inline data reads */
+	if (inode->i_flags & EXT4_INLINE_DATA_FL)
+		return -ENOSYS;
+
+	if (inode->i_flags & EXT4_EXTENTS_FL)
+		return fuse2fs_iomap_begin_extent(ff, ino, inode, pos, count,
+						  opflags, read);
+
+	return fuse2fs_iomap_begin_indirect(ff, ino, inode, pos, count,
+					    opflags, read);
 }
 
 static int fuse2fs_iomap_begin_write(struct fuse2fs *ff, ext2_ino_t ino,

[PATCH 06/17] fuse2fs: add extent dump function for debugging

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add a function to dump an inode's extent map for debugging purposes.
This helped debug a problem with generic/299 failing on 1k fsblock
filesystems:

 --- a/tests/generic/299.out	2025-07-15 14:45:15.030113607 -0700
 +++ b/tests/generic/299.out.bad	2025-07-16 19:33:50.889344998 -0700
 @@ -3,3 +3,4 @@ QA output created by 299
  Run fio with random aio-dio pattern

  Start fallocate/truncate loop
 +fio: io_u error on file /opt/direct_aio.0.0: Input/output error: write offset=2602827776, buflen=131072

(The cause of this was misuse of the libext2fs extent code)

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   73 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 misc/fuse2fs.c    |   73 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 146 insertions(+)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 90d94bb7404f90..03fc25de7b6fbb 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -735,6 +735,74 @@ static inline int fuse4fs_iomap_enabled(const struct fuse4fs *ff)
 # define fuse4fs_iomap_enabled(...)	(0)
 #endif
 
+static inline void fuse4fs_dump_extents(struct fuse4fs *ff, ext2_ino_t ino,
+					struct ext2_inode_large *inode,
+					const char *why)
+{
+	ext2_filsys fs = ff->fs;
+	unsigned int nr = 0;
+	blk64_t blockcount = 0;
+	struct ext2_inode_large xinode;
+	struct ext2fs_extent extent;
+	ext2_extent_handle_t extents;
+	int op = EXT2_EXTENT_ROOT;
+	errcode_t retval;
+
+	if (!inode) {
+		inode = &xinode;
+
+		retval = fuse4fs_read_inode(fs, ino, inode);
+		if (retval) {
+			com_err(__func__, retval, _("reading ino %u"), ino);
+			return;
+		}
+	}
+
+	if (!(inode->i_flags & EXT4_EXTENTS_FL))
+		return;
+
+	printf("%s: %s ino=%u isize %llu iblocks %llu\n", __func__, why, ino,
+	       EXT2_I_SIZE(inode),
+	       (ext2fs_get_stat_i_blocks(fs, EXT2_INODE(inode)) * 512) /
+	        fs->blocksize);
+	fflush(stdout);
+
+	retval = ext2fs_extent_open(fs, ino, &extents);
+	if (retval) {
+		com_err(__func__, retval, _("opening extents of ino \"%u\""),
+			ino);
+		return;
+	}
+
+	while ((retval = ext2fs_extent_get(extents, op, &extent)) == 0) {
+		op = EXT2_EXTENT_NEXT;
+
+		if (extent.e_flags & EXT2_EXTENT_FLAGS_SECOND_VISIT)
+			continue;
+
+		printf("[%u]: %s ino=%u lblk 0x%llx pblk 0x%llx len 0x%x flags 0x%x\n",
+		       nr++, why, ino, extent.e_lblk, extent.e_pblk,
+		       extent.e_len, extent.e_flags);
+		fflush(stdout);
+		if (extent.e_flags & EXT2_EXTENT_FLAGS_LEAF)
+			blockcount += extent.e_len;
+		else
+			blockcount++;
+	}
+	if (retval == EXT2_ET_EXTENT_NO_NEXT)
+		retval = 0;
+	if (retval) {
+		com_err(__func__, retval, ("getting extents of ino %u"),
+			ino);
+	}
+	if (inode->i_file_acl)
+		blockcount++;
+	printf("%s: %s sum(e_len) %llu\n", __func__, why, blockcount);
+	fflush(stdout);
+
+	ext2fs_extent_free(extents);
+}
+
 static void get_now(struct timespec *now)
 {
 #ifdef CLOCK_REALTIME
@@ -5907,6 +5975,11 @@ static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 		   read.type,
 		   read.flags);
 
+	/* Not filling even the first byte will make the kernel unhappy. */
+	if (ff->debug && (read.offset > pos ||
+			  read.offset + read.length <= pos))
+		fuse4fs_dump_extents(ff, ino, &inode, "BAD DATA");
+
 out_unlock:
 	fuse4fs_finish(ff, ret);
 	if (ret)
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 31fd882dac4ef6..76540f4fc3c694 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -572,6 +572,74 @@ static inline int fuse2fs_iomap_enabled(const struct fuse2fs *ff)
 # define fuse2fs_iomap_enabled(...)	(0)
 #endif
 
+static inline void fuse2fs_dump_extents(struct fuse2fs *ff, ext2_ino_t ino,
+					struct ext2_inode_large *inode,
+					const char *why)
+{
+	ext2_filsys fs = ff->fs;
+	unsigned int nr = 0;
+	blk64_t blockcount = 0;
+	struct ext2_inode_large xinode;
+	struct ext2fs_extent extent;
+	ext2_extent_handle_t extents;
+	int op = EXT2_EXTENT_ROOT;
+	errcode_t retval;
+
+	if (!inode) {
+		inode = &xinode;
+
+		retval = fuse2fs_read_inode(fs, ino, inode);
+		if (retval) {
+			com_err(__func__, retval, _("reading ino %u"), ino);
+			return;
+		}
+	}
+
+	if (!(inode->i_flags & EXT4_EXTENTS_FL))
+		return;
+
+	printf("%s: %s ino=%u isize %llu iblocks %llu\n", __func__, why, ino,
+	       EXT2_I_SIZE(inode),
+	       (ext2fs_get_stat_i_blocks(fs, EXT2_INODE(inode)) * 512) /
+	        fs->blocksize);
+	fflush(stdout);
+
+	retval = ext2fs_extent_open(fs, ino, &extents);
+	if (retval) {
+		com_err(__func__, retval, _("opening extents of ino \"%u\""),
+			ino);
+		return;
+	}
+
+	while ((retval = ext2fs_extent_get(extents, op, &extent)) == 0) {
+		op = EXT2_EXTENT_NEXT;
+
+		if (extent.e_flags & EXT2_EXTENT_FLAGS_SECOND_VISIT)
+			continue;
+
+		printf("[%u]: %s ino=%u lblk 0x%llx pblk 0x%llx len 0x%x flags 0x%x\n",
+		       nr++, why, ino, extent.e_lblk, extent.e_pblk,
+		       extent.e_len, extent.e_flags);
+		fflush(stdout);
+		if (extent.e_flags & EXT2_EXTENT_FLAGS_LEAF)
+			blockcount += extent.e_len;
+		else
+			blockcount++;
+	}
+	if (retval == EXT2_ET_EXTENT_NO_NEXT)
+		retval = 0;
+	if (retval) {
+		com_err(__func__, retval, ("getting extents of ino %u"),
+			ino);
+	}
+	if (inode->i_file_acl)
+		blockcount++;
+	printf("%s: %s sum(e_len) %llu\n", __func__, why, blockcount);
+	fflush(stdout);
+
+	ext2fs_extent_free(extents);
+}
+
 static void get_now(struct timespec *now)
 {
 #ifdef CLOCK_REALTIME
@@ -5351,6 +5419,11 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 		   (unsigned long long)read->length,
 		   read->type);
 
+	/* Not filling even the first byte will make the kernel unhappy. */
+	if (ff->debug && (read->offset > pos ||
+			  read->offset + read->length <= pos))
+		fuse2fs_dump_extents(ff, attr_ino, &inode, "BAD DATA");
+
 out_unlock:
 	fuse2fs_finish(ff, ret);
 	return ret;

[PATCH 07/17] fuse2fs: implement direct write support

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Wire up an iomap_begin method that can allocate into holes so that we
can do directio writes.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |  473 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 misc/fuse2fs.c    |  470 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 937 insertions(+), 6 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 03fc25de7b6fbb..b7184e3416860d 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -5918,12 +5918,106 @@ static int fuse4fs_iomap_begin_read(struct fuse4fs *ff, ext2_ino_t ino,
 					    opflags, read);
 }
 
+static int fuse4fs_iomap_write_allocate(struct fuse4fs *ff, ext2_ino_t ino,
+					struct ext2_inode_large *inode,
+					off_t pos, uint64_t count,
+					uint32_t opflags,
+					struct fuse_file_iomap *read,
+					bool *dirty)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t startoff = FUSE4FS_B_TO_FSBT(ff, pos);
+	blk64_t stopoff = FUSE4FS_B_TO_FSB(ff, pos + count);
+	blk64_t old_iblocks;
+	errcode_t err;
+	int ret;
+
+	dbg_printf(ff,
+ "%s: ino=%d startoff 0x%llx blockcount 0x%llx\n",
+		   __func__, ino, startoff, stopoff - startoff);
+
+	if (!fuse4fs_can_allocate(ff, stopoff - startoff))
+		return -ENOSPC;
+
+	old_iblocks = ext2fs_get_stat_i_blocks(fs, EXT2_INODE(inode));
+	err = ext2fs_fallocate(fs, EXT2_FALLOCATE_FORCE_UNINIT, ino,
+			       EXT2_INODE(inode), ~0ULL, startoff,
+			       stopoff - startoff);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/*
+	 * New allocations for file data blocks on indirect mapped files are
+	 * zeroed through the IO manager so we have to flush it to disk.
+	 */
+	if (!(inode->i_flags & EXT4_EXTENTS_FL) &&
+	    old_iblocks != ext2fs_get_stat_i_blocks(fs, EXT2_INODE(inode))) {
+		err = io_channel_flush(fs->io);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	/* pick up the newly allocated mapping */
+	ret = fuse4fs_iomap_begin_read(ff, ino, inode, pos, count, opflags,
+				       read);
+	if (ret)
+		return ret;
+
+	read->flags |= FUSE_IOMAP_F_DIRTY;
+	*dirty = true;
+	return 0;
+}
+
+static off_t fuse4fs_max_file_size(const struct fuse4fs *ff,
+				   const struct ext2_inode_large *inode)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t addr_per_block, max_map_block;
+
+	if (inode->i_flags & EXT4_EXTENTS_FL) {
+		max_map_block = (1ULL << 32) - 1;
+	} else {
+		addr_per_block = fs->blocksize >> 2;
+		max_map_block = addr_per_block;
+		max_map_block += addr_per_block * addr_per_block;
+		max_map_block += addr_per_block * addr_per_block * addr_per_block;
+		max_map_block += 12;
+	}
+
+	return FUSE4FS_FSB_TO_B(ff, max_map_block) + (fs->blocksize - 1);
+}
+
 static int fuse4fs_iomap_begin_write(struct fuse4fs *ff, ext2_ino_t ino,
 				     struct ext2_inode_large *inode, off_t pos,
 				     uint64_t count, uint32_t opflags,
-				     struct fuse_file_iomap *read)
+				     struct fuse_file_iomap *read,
+				     bool *dirty)
 {
-	return -ENOSYS;
+	off_t max_size = fuse4fs_max_file_size(ff, inode);
+	int ret;
+
+	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
+		return -ENOSYS;
+
+	if (pos >= max_size)
+		return -EFBIG;
+
+	if (pos >= max_size - count)
+		count = max_size - pos;
+
+	ret = fuse4fs_iomap_begin_read(ff, ino, inode, pos, count, opflags,
+				       read);
+	if (ret)
+		return ret;
+
+	if (fuse_iomap_need_write_allocate(opflags, read)) {
+		ret = fuse4fs_iomap_write_allocate(ff, ino, inode, pos, count,
+						   opflags, read, dirty);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
 
 static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
@@ -5935,6 +6029,7 @@ static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 	ext2_filsys fs;
 	ext2_ino_t ino;
 	errcode_t err;
+	bool dirty = false;
 	int ret = 0;
 
 	FUSE4FS_CHECK_CONTEXT(req);
@@ -5958,7 +6053,7 @@ static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 						 opflags, &read);
 	else if (fuse_iomap_is_write(opflags))
 		ret = fuse4fs_iomap_begin_write(ff, ino, &inode, pos, count,
-						opflags, &read);
+						opflags, &read, &dirty);
 	else
 		ret = fuse4fs_iomap_begin_read(ff, ino, &inode, pos, count,
 					       opflags, &read);
@@ -5980,6 +6075,14 @@ static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 			  read.offset + read.length <= pos))
 		fuse4fs_dump_extents(ff, ino, &inode, "BAD DATA");
 
+	if (dirty) {
+		err = fuse4fs_write_inode(fs, ino, &inode);
+		if (err) {
+			ret = translate_error(fs, ino, err);
+			goto out_unlock;
+		}
+	}
+
 out_unlock:
 	fuse4fs_finish(ff, ret);
 	if (ret)
@@ -6127,6 +6230,369 @@ static void op_iomap_config(fuse_req_t req, uint64_t flags, uint64_t maxbytes)
 	else
 		fuse_reply_iomap_config(req, &cfg);
 }
+
+static inline bool fuse4fs_can_merge_mappings(const struct ext2fs_extent *left,
+					      const struct ext2fs_extent *right)
+{
+	uint64_t max_len = (left->e_flags & EXT2_EXTENT_FLAGS_UNINIT) ?
+				EXT_UNINIT_MAX_LEN : EXT_INIT_MAX_LEN;
+
+	return left->e_lblk + left->e_len == right->e_lblk &&
+	       left->e_pblk + left->e_len == right->e_pblk &&
+	       (left->e_flags & EXT2_EXTENT_FLAGS_UNINIT) ==
+	        (right->e_flags & EXT2_EXTENT_FLAGS_UNINIT) &&
+	       (uint64_t)left->e_len + right->e_len <= max_len;
+}
+
+static int fuse4fs_try_merge_mappings(struct fuse4fs *ff, ext2_ino_t ino,
+				      ext2_extent_handle_t handle,
+				      blk64_t startoff)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2fs_extent left, right;
+	errcode_t err;
+
+	/* Look up the mappings before startoff */
+	err = fuse4fs_get_mapping_at(ff, handle, startoff - 1, &left);
+	if (err == EXT2_ET_EXTENT_NOT_FOUND)
+		return 0;
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/* Look up the mapping at startoff */
+	err = fuse4fs_get_mapping_at(ff, handle, startoff, &right);
+	if (err == EXT2_ET_EXTENT_NOT_FOUND)
+		return 0;
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/* Can we combine them? */
+	if (!fuse4fs_can_merge_mappings(&left, &right))
+		return 0;
+
+	/*
+	 * Delete the mapping after startoff because libext2fs cannot handle
+	 * overlapping mappings.
+	 */
+	err = ext2fs_extent_delete(handle, 0);
+	DUMP_EXTENT(ff, "remover", startoff, err, &right);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_extent_fix_parents(handle);
+	DUMP_EXTENT(ff, "fixremover", startoff, err, &right);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/* Move back and lengthen the mapping before startoff */
+	err = ext2fs_extent_goto(handle, left.e_lblk);
+	DUMP_EXTENT(ff, "movel", startoff - 1, err, &left);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	left.e_len += right.e_len;
+	err = ext2fs_extent_replace(handle, 0, &left);
+	DUMP_EXTENT(ff, "replacel", startoff - 1, err, &left);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_extent_fix_parents(handle);
+	DUMP_EXTENT(ff, "fixreplacel", startoff - 1, err, &left);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
+static int fuse4fs_convert_unwritten_mapping(struct fuse4fs *ff,
+					     ext2_ino_t ino,
+					     struct ext2_inode_large *inode,
+					     ext2_extent_handle_t handle,
+					     blk64_t *cursor, blk64_t stopoff)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2fs_extent extent;
+	blk64_t startoff = *cursor;
+	errcode_t err;
+
+	/*
+	 * Find the mapping at startoff.  Note that we can find holes because
+	 * the mapping data can change due to racing writes.
+	 */
+	err = fuse4fs_get_mapping_at(ff, handle, startoff, &extent);
+	if (err == EXT2_ET_EXTENT_NOT_FOUND) {
+		/*
+		 * If we didn't find any mappings at all then the file is
+		 * completely sparse.  There's nothing to convert.
+		 */
+		*cursor = stopoff;
+		return 0;
+	}
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/*
+	 * The mapping is completely to the left of the range that we want.
+	 * Let's see what's in the next extent, if there is one.
+	 */
+	if (startoff >= extent.e_lblk + extent.e_len) {
+		/*
+		 * Mapping ends to the left of the current position.  Try to
+		 * find the next mapping.  If there is no next mapping, then
+		 * we're done.
+		 */
+		err = fuse4fs_get_next_mapping(ff, handle, startoff, &extent);
+		if (err == EXT2_ET_EXTENT_NOT_FOUND) {
+			*cursor = stopoff;
+			return 0;
+		}
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	/*
+	 * The mapping is completely to the right of the range that we want,
+	 * so we're done.
+	 */
+	if (extent.e_lblk >= stopoff) {
+		*cursor = stopoff;
+		return 0;
+	}
+
+	/*
+	 * At this point, we have a mapping that overlaps (startoff, stopoff].
+	 * If the mapping is already written, move on to the next one.
+	 */
+	if (!(extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT))
+		goto next;
+
+	if (startoff > extent.e_lblk) {
+		struct ext2fs_extent newex = extent;
+
+		/*
+		 * Unwritten mapping starts before startoff.  Shorten
+		 * the previous mapping...
+		 */
+		newex.e_len = startoff - extent.e_lblk;
+		err = ext2fs_extent_replace(handle, 0, &newex);
+		DUMP_EXTENT(ff, "shortenp", startoff, err, &newex);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixshortenp", startoff, err, &newex);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		/* ...and create new written mapping at startoff. */
+		extent.e_len -= newex.e_len;
+		extent.e_lblk += newex.e_len;
+		extent.e_pblk += newex.e_len;
+		extent.e_flags = newex.e_flags & ~EXT2_EXTENT_FLAGS_UNINIT;
+
+		err = ext2fs_extent_insert(handle,
+					   EXT2_EXTENT_INSERT_AFTER,
+					   &extent);
+		DUMP_EXTENT(ff, "insertx", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixinsertx", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	if (extent.e_lblk + extent.e_len > stopoff) {
+		struct ext2fs_extent newex = extent;
+
+		/*
+		 * Unwritten mapping ends after stopoff.  Shorten the current
+		 * mapping...
+		 */
+		extent.e_len = stopoff - extent.e_lblk;
+		extent.e_flags &= ~EXT2_EXTENT_FLAGS_UNINIT;
+
+		err = ext2fs_extent_replace(handle, 0, &extent);
+		DUMP_EXTENT(ff, "shortenn", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixshortenn", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		/* ..and create a new unwritten mapping at stopoff. */
+		newex.e_pblk += extent.e_len;
+		newex.e_lblk += extent.e_len;
+		newex.e_len -= extent.e_len;
+		newex.e_flags |= EXT2_EXTENT_FLAGS_UNINIT;
+
+		err = ext2fs_extent_insert(handle,
+					   EXT2_EXTENT_INSERT_AFTER,
+					   &newex);
+		DUMP_EXTENT(ff, "insertn", startoff, err, &newex);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixinsertn", startoff, err, &newex);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	/* Still unwritten?  Update the state. */
+	if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT) {
+		extent.e_flags &= ~EXT2_EXTENT_FLAGS_UNINIT;
+
+		err = ext2fs_extent_replace(handle, 0, &extent);
+		DUMP_EXTENT(ff, "replacex", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixreplacex", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+next:
+	/* Try to merge with the previous extent */
+	if (startoff > 0) {
+		err = fuse4fs_try_merge_mappings(ff, ino, handle, startoff);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	*cursor = extent.e_lblk + extent.e_len;
+	return 0;
+}
+
+static int fuse4fs_convert_unwritten_mappings(struct fuse4fs *ff,
+					      ext2_ino_t ino,
+					      struct ext2_inode_large *inode,
+					      off_t pos, size_t written)
+{
+	ext2_extent_handle_t handle;
+	ext2_filsys fs = ff->fs;
+	blk64_t startoff = FUSE4FS_B_TO_FSBT(ff, pos);
+	const blk64_t stopoff = FUSE4FS_B_TO_FSB(ff, pos + written);
+	errcode_t err;
+	int ret;
+
+	err = ext2fs_extent_open2(fs, ino, EXT2_INODE(inode), &handle);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/* Walk every mapping in the range, converting them. */
+	while (startoff < stopoff) {
+		blk64_t old_startoff = startoff;
+
+		ret = fuse4fs_convert_unwritten_mapping(ff, ino, inode, handle,
+							&startoff, stopoff);
+		if (ret)
+			goto out_handle;
+		if (startoff <= old_startoff) {
+			/* Do not go backwards. */
+			ret = translate_error(fs, ino, EXT2_ET_INODE_CORRUPTED);
+			goto out_handle;
+		}
+	}
+
+	/* Try to merge the right edge */
+	ret = fuse4fs_try_merge_mappings(ff, ino, handle, stopoff);
+out_handle:
+	ext2fs_extent_free(handle);
+	return ret;
+}
+
+static void op_iomap_ioend(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
+			   off_t pos, size_t written, uint32_t ioendflags,
+			   int error, uint64_t new_addr)
+{
+	struct fuse4fs *ff = fuse4fs_get(req);
+	struct ext2_inode_large inode;
+	ext2_filsys fs;
+	ext2_ino_t ino;
+	errcode_t err;
+	bool dirty = false;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+
+	dbg_printf(ff,
+ "%s: ino=%d pos=0x%llx written=0x%zx ioendflags=0x%x error=%d new_addr=0x%llx\n",
+		   __func__, ino,
+		   (unsigned long long)pos,
+		   written,
+		   ioendflags,
+		   error,
+		   (unsigned long long)new_addr);
+
+	if (error) {
+		fuse_reply_err(req, -error);
+		return;
+	}
+
+	fs = fuse4fs_start(ff);
+
+	/* should never see these ioend types */
+	if (ioendflags & FUSE_IOMAP_IOEND_SHARED) {
+		ret = translate_error(fs, ino, EXT2_ET_FILESYSTEM_CORRUPTED);
+		goto out_unlock;
+	}
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err) {
+		ret = translate_error(fs, ino, err);
+		goto out_unlock;
+	}
+
+	if (ioendflags & FUSE_IOMAP_IOEND_UNWRITTEN) {
+		/* unwritten extents are only supported on extents files */
+		if (!(inode.i_flags & EXT4_EXTENTS_FL)) {
+			ret = translate_error(fs, ino,
+					      EXT2_ET_FILESYSTEM_CORRUPTED);
+			goto out_unlock;
+		}
+
+		ret = fuse4fs_convert_unwritten_mappings(ff, ino, &inode,
+							 pos, written);
+		if (ret)
+			goto out_unlock;
+
+		dirty = true;
+	}
+
+	if (ioendflags & FUSE_IOMAP_IOEND_APPEND) {
+		ext2_off64_t isize = EXT2_I_SIZE(&inode);
+
+		if (pos + written > isize) {
+			err = ext2fs_inode_size_set(fs, EXT2_INODE(&inode),
+						    pos + written);
+			if (err) {
+				ret = translate_error(fs, ino, err);
+				goto out_unlock;
+			}
+
+			dirty = true;
+		}
+	}
+
+	if (dirty) {
+		err = fuse4fs_write_inode(fs, ino, &inode);
+		if (err) {
+			ret = translate_error(fs, ino, err);
+			goto out_unlock;
+		}
+	}
+
+out_unlock:
+	fuse4fs_finish(ff, ret);
+	fuse_reply_err(req, -ret);
+}
 #endif /* HAVE_FUSE_IOMAP */
 
 static struct fuse_lowlevel_ops fs_ops = {
@@ -6176,6 +6642,7 @@ static struct fuse_lowlevel_ops fs_ops = {
 	.iomap_begin = op_iomap_begin,
 	.iomap_end = op_iomap_end,
 	.iomap_config = op_iomap_config,
+	.iomap_ioend = op_iomap_ioend,
 #endif /* HAVE_FUSE_IOMAP */
 };
 
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 76540f4fc3c694..9bcf2c81b7e732 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -5360,12 +5360,103 @@ static int fuse2fs_iomap_begin_read(struct fuse2fs *ff, ext2_ino_t ino,
 					    opflags, read);
 }
 
+static int fuse2fs_iomap_write_allocate(struct fuse2fs *ff, ext2_ino_t ino,
+				     struct ext2_inode_large *inode, off_t pos,
+				     uint64_t count, uint32_t opflags,
+				     struct fuse_file_iomap *read, bool *dirty)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t startoff = FUSE2FS_B_TO_FSBT(ff, pos);
+	blk64_t stopoff = FUSE2FS_B_TO_FSB(ff, pos + count);
+	blk64_t old_iblocks;
+	errcode_t err;
+	int ret;
+
+	dbg_printf(ff, "%s: write_alloc ino=%u startoff 0x%llx blockcount 0x%llx\n",
+		   __func__, ino, startoff, stopoff - startoff);
+
+	if (!fs_can_allocate(ff, stopoff - startoff))
+		return -ENOSPC;
+
+	old_iblocks = ext2fs_get_stat_i_blocks(fs, EXT2_INODE(inode));
+	err = ext2fs_fallocate(fs, EXT2_FALLOCATE_FORCE_UNINIT, ino,
+			       EXT2_INODE(inode), ~0ULL, startoff,
+			       stopoff - startoff);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/*
+	 * New allocations for file data blocks on indirect mapped files are
+	 * zeroed through the IO manager so we have to flush it to disk.
+	 */
+	if (!(inode->i_flags & EXT4_EXTENTS_FL) &&
+	    old_iblocks != ext2fs_get_stat_i_blocks(fs, EXT2_INODE(inode))) {
+		err = io_channel_flush(fs->io);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	/* pick up the newly allocated mapping */
+	ret = fuse2fs_iomap_begin_read(ff, ino, inode, pos, count, opflags,
+				       read);
+	if (ret)
+		return ret;
+
+	read->flags |= FUSE_IOMAP_F_DIRTY;
+	*dirty = true;
+	return 0;
+}
+
+static off_t fuse2fs_max_file_size(const struct fuse2fs *ff,
+				   const struct ext2_inode_large *inode)
+{
+	ext2_filsys fs = ff->fs;
+	blk64_t addr_per_block, max_map_block;
+
+	if (inode->i_flags & EXT4_EXTENTS_FL) {
+		max_map_block = (1ULL << 32) - 1;
+	} else {
+		addr_per_block = fs->blocksize >> 2;
+		max_map_block = addr_per_block;
+		max_map_block += addr_per_block * addr_per_block;
+		max_map_block += addr_per_block * addr_per_block * addr_per_block;
+		max_map_block += 12;
+	}
+
+	return FUSE2FS_FSB_TO_B(ff, max_map_block) + (fs->blocksize - 1);
+}
+
 static int fuse2fs_iomap_begin_write(struct fuse2fs *ff, ext2_ino_t ino,
 				     struct ext2_inode_large *inode, off_t pos,
 				     uint64_t count, uint32_t opflags,
-				     struct fuse_file_iomap *read)
+				     struct fuse_file_iomap *read,
+				     bool *dirty)
 {
-	return -ENOSYS;
+	off_t max_size = fuse2fs_max_file_size(ff, inode);
+	int ret;
+
+	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
+		return -ENOSYS;
+
+	if (pos >= max_size)
+		return -EFBIG;
+
+	if (pos >= max_size - count)
+		count = max_size - pos;
+
+	ret = fuse2fs_iomap_begin_read(ff, ino, inode, pos, count, opflags,
+				       read);
+	if (ret)
+		return ret;
+
+	if (fuse_iomap_need_write_allocate(opflags, read)) {
+		ret = fuse2fs_iomap_write_allocate(ff, ino, inode, pos, count,
+						   opflags, read, dirty);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
 
 static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
@@ -5377,6 +5468,7 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 	struct ext2_inode_large inode;
 	ext2_filsys fs;
 	errcode_t err;
+	bool dirty = false;
 	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
@@ -5402,7 +5494,7 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 						 count, opflags, read);
 	else if (fuse_iomap_is_write(opflags))
 		ret = fuse2fs_iomap_begin_write(ff, attr_ino, &inode, pos,
-						count, opflags, read);
+						count, opflags, read, &dirty);
 	else
 		ret = fuse2fs_iomap_begin_read(ff, attr_ino, &inode, pos,
 					       count, opflags, read);
@@ -5424,6 +5516,14 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 			  read->offset + read->length <= pos))
 		fuse2fs_dump_extents(ff, attr_ino, &inode, "BAD DATA");
 
+	if (dirty) {
+		err = fuse2fs_write_inode(fs, attr_ino, &inode);
+		if (err) {
+			ret = translate_error(fs, attr_ino, err);
+			goto out_unlock;
+		}
+	}
+
 out_unlock:
 	fuse2fs_finish(ff, ret);
 	return ret;
@@ -5561,6 +5661,369 @@ static int op_iomap_config(uint64_t flags, off_t maxbytes,
 	if (ret)
 		goto out_unlock;
 
+out_unlock:
+	fuse2fs_finish(ff, ret);
+	return ret;
+}
+
+static inline bool fuse2fs_can_merge_mappings(const struct ext2fs_extent *left,
+					      const struct ext2fs_extent *right)
+{
+	uint64_t max_len = (left->e_flags & EXT2_EXTENT_FLAGS_UNINIT) ?
+				EXT_UNINIT_MAX_LEN : EXT_INIT_MAX_LEN;
+
+	return left->e_lblk + left->e_len == right->e_lblk &&
+	       left->e_pblk + left->e_len == right->e_pblk &&
+	       (left->e_flags & EXT2_EXTENT_FLAGS_UNINIT) ==
+	        (right->e_flags & EXT2_EXTENT_FLAGS_UNINIT) &&
+	       (uint64_t)left->e_len + right->e_len <= max_len;
+}
+
+static int fuse2fs_try_merge_mappings(struct fuse2fs *ff, ext2_ino_t ino,
+				      ext2_extent_handle_t handle,
+				      blk64_t startoff)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2fs_extent left, right;
+	errcode_t err;
+
+	/* Look up the mappings before startoff */
+	err = fuse2fs_get_mapping_at(ff, handle, startoff - 1, &left);
+	if (err == EXT2_ET_EXTENT_NOT_FOUND)
+		return 0;
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/* Look up the mapping at startoff */
+	err = fuse2fs_get_mapping_at(ff, handle, startoff, &right);
+	if (err == EXT2_ET_EXTENT_NOT_FOUND)
+		return 0;
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/* Can we combine them? */
+	if (!fuse2fs_can_merge_mappings(&left, &right))
+		return 0;
+
+	/*
+	 * Delete the mapping after startoff because libext2fs cannot handle
+	 * overlapping mappings.
+	 */
+	err = ext2fs_extent_delete(handle, 0);
+	DUMP_EXTENT(ff, "remover", startoff, err, &right);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_extent_fix_parents(handle);
+	DUMP_EXTENT(ff, "fixremover", startoff, err, &right);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/* Move back and lengthen the mapping before startoff */
+	err = ext2fs_extent_goto(handle, left.e_lblk);
+	DUMP_EXTENT(ff, "movel", startoff - 1, err, &left);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	left.e_len += right.e_len;
+	err = ext2fs_extent_replace(handle, 0, &left);
+	DUMP_EXTENT(ff, "replacel", startoff - 1, err, &left);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_extent_fix_parents(handle);
+	DUMP_EXTENT(ff, "fixreplacel", startoff - 1, err, &left);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
+static int fuse2fs_convert_unwritten_mapping(struct fuse2fs *ff,
+					     ext2_ino_t ino,
+					     struct ext2_inode_large *inode,
+					     ext2_extent_handle_t handle,
+					     blk64_t *cursor, blk64_t stopoff)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2fs_extent extent;
+	blk64_t startoff = *cursor;
+	errcode_t err;
+
+	/*
+	 * Find the mapping at startoff.  Note that we can find holes because
+	 * the mapping data can change due to racing writes.
+	 */
+	err = fuse2fs_get_mapping_at(ff, handle, startoff, &extent);
+	if (err == EXT2_ET_EXTENT_NOT_FOUND) {
+		/*
+		 * If we didn't find any mappings at all then the file is
+		 * completely sparse.  There's nothing to convert.
+		 */
+		*cursor = stopoff;
+		return 0;
+	}
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/*
+	 * The mapping is completely to the left of the range that we want.
+	 * Let's see what's in the next extent, if there is one.
+	 */
+	if (startoff >= extent.e_lblk + extent.e_len) {
+		/*
+		 * Mapping ends to the left of the current position.  Try to
+		 * find the next mapping.  If there is no next mapping, then
+		 * we're done.
+		 */
+		err = fuse2fs_get_next_mapping(ff, handle, startoff, &extent);
+		if (err == EXT2_ET_EXTENT_NOT_FOUND) {
+			*cursor = stopoff;
+			return 0;
+		}
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	/*
+	 * The mapping is completely to the right of the range that we want,
+	 * so we're done.
+	 */
+	if (extent.e_lblk >= stopoff) {
+		*cursor = stopoff;
+		return 0;
+	}
+
+	/*
+	 * At this point, we have a mapping that overlaps (startoff, stopoff].
+	 * If the mapping is already written, move on to the next one.
+	 */
+	if (!(extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT))
+		goto next;
+
+	if (startoff > extent.e_lblk) {
+		struct ext2fs_extent newex = extent;
+
+		/*
+		 * Unwritten mapping starts before startoff.  Shorten
+		 * the previous mapping...
+		 */
+		newex.e_len = startoff - extent.e_lblk;
+		err = ext2fs_extent_replace(handle, 0, &newex);
+		DUMP_EXTENT(ff, "shortenp", startoff, err, &newex);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixshortenp", startoff, err, &newex);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		/* ...and create new written mapping at startoff. */
+		extent.e_len -= newex.e_len;
+		extent.e_lblk += newex.e_len;
+		extent.e_pblk += newex.e_len;
+		extent.e_flags = newex.e_flags & ~EXT2_EXTENT_FLAGS_UNINIT;
+
+		err = ext2fs_extent_insert(handle,
+					   EXT2_EXTENT_INSERT_AFTER,
+					   &extent);
+		DUMP_EXTENT(ff, "insertx", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixinsertx", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	if (extent.e_lblk + extent.e_len > stopoff) {
+		struct ext2fs_extent newex = extent;
+
+		/*
+		 * Unwritten mapping ends after stopoff.  Shorten the current
+		 * mapping...
+		 */
+		extent.e_len = stopoff - extent.e_lblk;
+		extent.e_flags &= ~EXT2_EXTENT_FLAGS_UNINIT;
+
+		err = ext2fs_extent_replace(handle, 0, &extent);
+		DUMP_EXTENT(ff, "shortenn", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixshortenn", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		/* ..and create a new unwritten mapping at stopoff. */
+		newex.e_pblk += extent.e_len;
+		newex.e_lblk += extent.e_len;
+		newex.e_len -= extent.e_len;
+		newex.e_flags |= EXT2_EXTENT_FLAGS_UNINIT;
+
+		err = ext2fs_extent_insert(handle,
+					   EXT2_EXTENT_INSERT_AFTER,
+					   &newex);
+		DUMP_EXTENT(ff, "insertn", startoff, err, &newex);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixinsertn", startoff, err, &newex);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	/* Still unwritten?  Update the state. */
+	if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT) {
+		extent.e_flags &= ~EXT2_EXTENT_FLAGS_UNINIT;
+
+		err = ext2fs_extent_replace(handle, 0, &extent);
+		DUMP_EXTENT(ff, "replacex", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+
+		err = ext2fs_extent_fix_parents(handle);
+		DUMP_EXTENT(ff, "fixreplacex", startoff, err, &extent);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+next:
+	/* Try to merge with the previous extent */
+	if (startoff > 0) {
+		err = fuse2fs_try_merge_mappings(ff, ino, handle, startoff);
+		if (err)
+			return translate_error(fs, ino, err);
+	}
+
+	*cursor = extent.e_lblk + extent.e_len;
+	return 0;
+}
+
+static int fuse2fs_convert_unwritten_mappings(struct fuse2fs *ff,
+					      ext2_ino_t ino,
+					      struct ext2_inode_large *inode,
+					      off_t pos, size_t written)
+{
+	ext2_extent_handle_t handle;
+	ext2_filsys fs = ff->fs;
+	blk64_t startoff = FUSE2FS_B_TO_FSBT(ff, pos);
+	const blk64_t stopoff = FUSE2FS_B_TO_FSB(ff, pos + written);
+	errcode_t err;
+	int ret;
+
+	err = ext2fs_extent_open2(fs, ino, EXT2_INODE(inode), &handle);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	/* Walk every mapping in the range, converting them. */
+	while (startoff < stopoff) {
+		blk64_t old_startoff = startoff;
+
+		ret = fuse2fs_convert_unwritten_mapping(ff, ino, inode, handle,
+							&startoff, stopoff);
+		if (ret)
+			goto out_handle;
+		if (startoff <= old_startoff) {
+			/* Do not go backwards. */
+			ret = translate_error(fs, ino, EXT2_ET_INODE_CORRUPTED);
+			goto out_handle;
+		}
+	}
+
+	/* Try to merge the right edge */
+	ret = fuse2fs_try_merge_mappings(ff, ino, handle, stopoff);
+out_handle:
+	ext2fs_extent_free(handle);
+	return ret;
+}
+
+static int op_iomap_ioend(const char *path, uint64_t nodeid, uint64_t attr_ino,
+			  off_t pos, size_t written, uint32_t ioendflags,
+			  int error, uint64_t new_addr)
+{
+	struct fuse2fs *ff = fuse2fs_get();
+	struct ext2_inode_large inode;
+	ext2_filsys fs;
+	errcode_t err;
+	bool dirty = false;
+	int ret = 0;
+
+	FUSE2FS_CHECK_CONTEXT(ff);
+
+	dbg_printf(ff,
+ "%s: path=%s nodeid=%llu attr_ino=%llu pos=0x%llx written=0x%zx ioendflags=0x%x error=%d new_addr=%llu\n",
+		   __func__, path,
+		   (unsigned long long)nodeid,
+		   (unsigned long long)attr_ino,
+		   (unsigned long long)pos,
+		   written,
+		   ioendflags,
+		   error,
+		   (unsigned long long)new_addr);
+
+	fs = fuse2fs_start(ff);
+	if (error) {
+		ret = error;
+		goto out_unlock;
+	}
+
+	/* should never see these ioend types */
+	if (ioendflags & FUSE_IOMAP_IOEND_SHARED) {
+		ret = translate_error(fs, attr_ino,
+				      EXT2_ET_FILESYSTEM_CORRUPTED);
+		goto out_unlock;
+	}
+
+	err = fuse2fs_read_inode(fs, attr_ino, &inode);
+	if (err) {
+		ret = translate_error(fs, attr_ino, err);
+		goto out_unlock;
+	}
+
+	if (ioendflags & FUSE_IOMAP_IOEND_UNWRITTEN) {
+		/* unwritten extents are only supported on extents files */
+		if (!(inode.i_flags & EXT4_EXTENTS_FL)) {
+			ret = translate_error(fs, attr_ino,
+					      EXT2_ET_FILESYSTEM_CORRUPTED);
+			goto out_unlock;
+		}
+
+		ret = fuse2fs_convert_unwritten_mappings(ff, attr_ino, &inode,
+							 pos, written);
+		if (ret)
+			goto out_unlock;
+
+		dirty = true;
+	}
+
+	if (ioendflags & FUSE_IOMAP_IOEND_APPEND) {
+		ext2_off64_t isize = EXT2_I_SIZE(&inode);
+
+		if (pos + written > isize) {
+			err = ext2fs_inode_size_set(fs, EXT2_INODE(&inode),
+						    pos + written);
+			if (err) {
+				ret = translate_error(fs, attr_ino, err);
+				goto out_unlock;
+			}
+
+			dirty = true;
+		}
+	}
+
+	if (dirty) {
+		err = fuse2fs_write_inode(fs, attr_ino, &inode);
+		if (err) {
+			ret = translate_error(fs, attr_ino, err);
+			goto out_unlock;
+		}
+	}
+
 out_unlock:
 	fuse2fs_finish(ff, ret);
 	return ret;
@@ -5612,6 +6075,7 @@ static struct fuse_operations fs_ops = {
 	.iomap_begin = op_iomap_begin,
 	.iomap_end = op_iomap_end,
 	.iomap_config = op_iomap_config,
+	.iomap_ioend = op_iomap_ioend,
 #endif /* HAVE_FUSE_IOMAP */
 };
 

[PATCH 08/17] fuse2fs: turn on iomap for pagecache IO

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Turn on iomap for pagecache IO to regular files.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   61 +++++++++++++++++++++++++++++++++++++++++++++++------
 misc/fuse2fs.c    |   61 +++++++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 108 insertions(+), 14 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index b7184e3416860d..6b5d14e4f044cb 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -5903,9 +5903,6 @@ static int fuse4fs_iomap_begin_read(struct fuse4fs *ff, ext2_ino_t ino,
 				    uint64_t count, uint32_t opflags,
 				    struct fuse_file_iomap *read)
 {
-	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
-		return -ENOSYS;
-
 	/* fall back to slow path for inline data reads */
 	if (inode->i_flags & EXT4_INLINE_DATA_FL)
 		return -ENOSYS;
@@ -5996,9 +5993,6 @@ static int fuse4fs_iomap_begin_write(struct fuse4fs *ff, ext2_ino_t ino,
 	off_t max_size = fuse4fs_max_file_size(ff, inode);
 	int ret;
 
-	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
-		return -ENOSYS;
-
 	if (pos >= max_size)
 		return -EFBIG;
 
@@ -6091,12 +6085,51 @@ static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 		fuse_reply_iomap_begin(req, &read, NULL);
 }
 
+static int fuse4fs_iomap_append_setsize(struct fuse4fs *ff, ext2_ino_t ino,
+					loff_t newsize)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_inode_large inode;
+	ext2_off64_t isize;
+	errcode_t err;
+
+	dbg_printf(ff, "%s: ino=%u newsize=%llu\n", __func__, ino,
+		   (unsigned long long)newsize);
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	isize = EXT2_I_SIZE(&inode);
+	if (newsize <= isize)
+		return 0;
+
+	dbg_printf(ff, "%s: ino=%u oldsize=%llu newsize=%llu\n", __func__, ino,
+		   (unsigned long long)isize,
+		   (unsigned long long)newsize);
+
+	/*
+	 * XXX cheesily update the ondisk size even though we only want to do
+	 * the incore size until writeback happens
+	 */
+	err = ext2fs_inode_size_set(fs, EXT2_INODE(&inode), newsize);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = fuse4fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
 static void op_iomap_end(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 			 off_t pos, uint64_t count, uint32_t opflags,
 			 ssize_t written, const struct fuse_file_iomap *iomap)
 {
 	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_ino_t ino;
+	int ret = 0;
 
 	FUSE4FS_CHECK_CONTEXT(req);
 	FUSE4FS_CONVERT_FINO(req, &ino, fino);
@@ -6110,7 +6143,21 @@ static void op_iomap_end(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 		   written,
 		   iomap->flags);
 
-	fuse_reply_err(req, 0);
+	fuse4fs_start(ff);
+
+	/* XXX is this really necessary? */
+	if ((opflags & FUSE_IOMAP_OP_WRITE) &&
+	    !(opflags & FUSE_IOMAP_OP_DIRECT) &&
+	    (iomap->flags & FUSE_IOMAP_F_SIZE_CHANGED) &&
+	    written > 0) {
+		ret = fuse4fs_iomap_append_setsize(ff, ino, pos + written);
+		if (ret)
+			goto out_unlock;
+	}
+
+out_unlock:
+	fuse4fs_finish(ff, ret);
+	fuse_reply_err(req, -ret);
 }
 
 /*
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 9bcf2c81b7e732..afc65c774dc148 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -5345,9 +5345,6 @@ static int fuse2fs_iomap_begin_read(struct fuse2fs *ff, ext2_ino_t ino,
 				    uint64_t count, uint32_t opflags,
 				    struct fuse_file_iomap *read)
 {
-	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
-		return -ENOSYS;
-
 	/* fall back to slow path for inline data reads */
 	if (inode->i_flags & EXT4_INLINE_DATA_FL)
 		return -ENOSYS;
@@ -5435,9 +5432,6 @@ static int fuse2fs_iomap_begin_write(struct fuse2fs *ff, ext2_ino_t ino,
 	off_t max_size = fuse2fs_max_file_size(ff, inode);
 	int ret;
 
-	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
-		return -ENOSYS;
-
 	if (pos >= max_size)
 		return -EFBIG;
 
@@ -5529,11 +5523,50 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 	return ret;
 }
 
+static int fuse2fs_iomap_append_setsize(struct fuse2fs *ff, ext2_ino_t ino,
+					loff_t newsize)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_inode_large inode;
+	ext2_off64_t isize;
+	errcode_t err;
+
+	dbg_printf(ff, "%s: ino=%u newsize=%llu\n", __func__, ino,
+		   (unsigned long long)newsize);
+
+	err = fuse2fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	isize = EXT2_I_SIZE(&inode);
+	if (newsize <= isize)
+		return 0;
+
+	dbg_printf(ff, "%s: ino=%u oldsize=%llu newsize=%llu\n", __func__, ino,
+		   (unsigned long long)isize,
+		   (unsigned long long)newsize);
+
+	/*
+	 * XXX cheesily update the ondisk size even though we only want to do
+	 * the incore size until writeback happens
+	 */
+	err = ext2fs_inode_size_set(fs, EXT2_INODE(&inode), newsize);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = fuse2fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
 static int op_iomap_end(const char *path, uint64_t nodeid, uint64_t attr_ino,
 			off_t pos, uint64_t count, uint32_t opflags,
 			ssize_t written, const struct fuse_file_iomap *iomap)
 {
 	struct fuse2fs *ff = fuse2fs_get();
+	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
 
@@ -5548,7 +5581,21 @@ static int op_iomap_end(const char *path, uint64_t nodeid, uint64_t attr_ino,
 		   written,
 		   iomap->flags);
 
-	return 0;
+	fuse2fs_start(ff);
+
+	/* XXX is this really necessary? */
+	if ((opflags & FUSE_IOMAP_OP_WRITE) &&
+	    !(opflags & FUSE_IOMAP_OP_DIRECT) &&
+	    (iomap->flags & FUSE_IOMAP_F_SIZE_CHANGED) &&
+	    written > 0) {
+		ret = fuse2fs_iomap_append_setsize(ff, attr_ino, pos + written);
+		if (ret)
+			goto out_unlock;
+	}
+
+out_unlock:
+	fuse2fs_finish(ff, ret);
+	return ret;
 }
 
 /*

[PATCH 09/17] fuse2fs: don't zero bytes in punch hole

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

When iomap is in use for the pagecache, it will take care of zeroing the
unaligned parts of punched out regions so we don't have to do it
ourselves.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |    8 ++++++++
 misc/fuse2fs.c    |    9 +++++++++
 2 files changed, 17 insertions(+)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 6b5d14e4f044cb..6c9e725d54b87a 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -5333,6 +5333,10 @@ static errcode_t fuse4fs_zero_middle(struct fuse4fs *ff, ext2_ino_t ino,
 	int retflags;
 	errcode_t err;
 
+	/* the kernel does this for us in iomap mode */
+	if (fuse4fs_iomap_enabled(ff))
+		return 0;
+
 	if (!*buf) {
 		err = ext2fs_get_mem(fs->blocksize, buf);
 		if (err)
@@ -5369,6 +5373,10 @@ static errcode_t fuse4fs_zero_edge(struct fuse4fs *ff, ext2_ino_t ino,
 	off_t residue;
 	errcode_t err;
 
+	/* the kernel does this for us in iomap mode */
+	if (fuse4fs_iomap_enabled(ff))
+		return 0;
+
 	residue = FUSE4FS_OFF_IN_FSB(ff, offset);
 	if (residue == 0)
 		return 0;
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index afc65c774dc148..5dbd8c5a17f79d 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -570,6 +570,7 @@ static inline int fuse2fs_iomap_enabled(const struct fuse2fs *ff)
 }
 #else
 # define fuse2fs_iomap_enabled(...)	(0)
+# define fuse2fs_iomap_enabled(...)	(0)
 #endif
 
 static inline void fuse2fs_dump_extents(struct fuse2fs *ff, ext2_ino_t ino,
@@ -4776,6 +4777,10 @@ static errcode_t clean_block_middle(struct fuse2fs *ff, ext2_ino_t ino,
 	int retflags;
 	errcode_t err;
 
+	/* the kernel does this for us in iomap mode */
+	if (fuse2fs_iomap_enabled(ff))
+		return 0;
+
 	if (!*buf) {
 		err = ext2fs_get_mem(fs->blocksize, buf);
 		if (err)
@@ -4812,6 +4817,10 @@ static errcode_t clean_block_edge(struct fuse2fs *ff, ext2_ino_t ino,
 	off_t residue;
 	errcode_t err;
 
+	/* the kernel does this for us in iomap mode */
+	if (fuse2fs_iomap_enabled(ff))
+		return 0;
+
 	residue = FUSE2FS_OFF_IN_FSB(ff, offset);
 	if (residue == 0)
 		return 0;

[PATCH 10/17] fuse2fs: don't do file data block IO when iomap is enabled

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

When iomap is in use for the page cache, the kernel will take care of
all the file data block IO for us, including zeroing of punched ranges
and post-EOF bytes.  fuse2fs only needs to do IO for inline data.

Therefore, set the NOBLOCKIO ext2_file flag so that libext2fs will not
do any regular file IO to or from disk blocks at all.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   11 +++++++-
 misc/fuse2fs.c    |   72 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 81 insertions(+), 2 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 6c9e725d54b87a..e482b00f14d572 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -3408,9 +3408,14 @@ static int fuse4fs_truncate(struct fuse4fs *ff, ext2_ino_t ino, off_t new_size)
 	ext2_file_t file;
 	__u64 old_isize;
 	errcode_t err;
+	int flags = EXT2_FILE_WRITE;
 	int ret = 0;
 
-	err = ext2fs_file_open(fs, ino, EXT2_FILE_WRITE, &file);
+	/* the kernel handles all eof zeroing for us in iomap mode */
+	if (fuse4fs_iomap_enabled(ff))
+		flags |= EXT2_FILE_NOBLOCKIO;
+
+	err = ext2fs_file_open(fs, ino, flags, &file);
 	if (err)
 		return translate_error(fs, ino, err);
 
@@ -3505,6 +3510,10 @@ static int fuse4fs_open_file(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 	if (linked)
 		check |= L_OK;
 
+	/* the kernel handles all block IO for us in iomap mode */
+	if (fuse4fs_iomap_enabled(ff))
+		file->open_flags |= EXT2_FILE_NOBLOCKIO;
+
 	/*
 	 * If the caller wants to truncate the file, we need to ask for full
 	 * write access even if the caller claims to be appending.
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 5dbd8c5a17f79d..c13bd6c3baf9c9 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -3145,15 +3145,72 @@ static int fuse2fs_punch_posteof(struct fuse2fs *ff, ext2_ino_t ino,
 	return 0;
 }
 
+/*
+ * Decide if file IO for this inode can use iomap.
+ *
+ * It turns out that libfuse creates internal node ids that have nothing to do
+ * with the ext2_ino_t that we give it.  These internal node ids are what
+ * actually gets igetted in the kernel, which means that there can be multiple
+ * fuse_inode objects in the kernel for a single hardlinked ondisk ext2 inode.
+ *
+ * What this means, horrifyingly, is that on a fuse filesystem that supports
+ * hard links, the in-kernel i_rwsem does not protect against concurrent writes
+ * between files that point to the same inode.  That in turn means that the
+ * file mode and size can get desynchronized between the multiple fuse_inode
+ * objects.  This also means that we cannot cache iomaps in the kernel AT ALL
+ * because the caches will get out of sync, leading to WARN_ONs from the iomap
+ * zeroing code and probably data corruption after that.
+ *
+ * Therefore, libfuse won't let us create hardlinks of iomap files, and we must
+ * never turn on iomap for existing hardlinked files.  Long term it means we
+ * have to find a way around this loss of functionality.  fuse4fs gets around
+ * this by being a low level fuse driver and controlling the nodeids itself.
+ *
+ * Returns 0 for no, 1 for yes, or a negative errno.
+ */
+#ifdef HAVE_FUSE_IOMAP
+static int fuse2fs_file_uses_iomap(struct fuse2fs *ff, ext2_ino_t ino)
+{
+	struct stat statbuf;
+	int ret;
+
+	if (!fuse2fs_iomap_enabled(ff))
+		return 0;
+
+	ret = stat_inode(ff->fs, ino, &statbuf);
+	if (ret)
+		return ret;
+
+	/* the kernel handles all block IO for us in iomap mode */
+	return fuse_fs_can_enable_iomap(&statbuf);
+}
+#else
+# define fuse2fs_file_uses_iomap(...)	(0)
+#endif
+
 static int fuse2fs_truncate(struct fuse2fs *ff, ext2_ino_t ino, off_t new_size)
 {
 	ext2_filsys fs = ff->fs;
 	ext2_file_t file;
 	__u64 old_isize;
 	errcode_t err;
+	int flags = EXT2_FILE_WRITE;
 	int ret = 0;
 
-	err = ext2fs_file_open(fs, ino, EXT2_FILE_WRITE, &file);
+	/* the kernel handles all eof zeroing for us in iomap mode */
+	ret = fuse2fs_file_uses_iomap(ff, ino);
+	switch (ret) {
+	case 0:
+		break;
+	case 1:
+		flags |= EXT2_FILE_NOBLOCKIO;
+		ret = 0;
+		break;
+	default:
+		return ret;
+	}
+
+	err = ext2fs_file_open(fs, ino, flags, &file);
 	if (err)
 		return translate_error(fs, ino, err);
 
@@ -3308,6 +3365,19 @@ static int __op_open(struct fuse2fs *ff, const char *path,
 			goto out;
 	}
 
+	/* the kernel handles all block IO for us in iomap mode */
+	ret = fuse2fs_file_uses_iomap(ff, file->ino);
+	switch (ret) {
+	case 0:
+		break;
+	case 1:
+		file->open_flags |= EXT2_FILE_NOBLOCKIO;
+		ret = 0;
+		break;
+	default:
+		goto out;
+	}
+
 	if (fp->flags & O_TRUNC) {
 		ret = fuse2fs_truncate(ff, file->ino, 0);
 		if (ret)

[PATCH 11/17] fuse2fs: avoid fuseblk mode if fuse-iomap support is likely

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Since fuse in iomap mode guarantees that op_destroy will be called
before umount returns, we don't need to use fuseblk mode to get that
guarantee.  Disable fuseblk mode, which saves us the trouble of closing
and reopening the device.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   20 +++++++++++++++++++-
 misc/fuse2fs.c    |   20 +++++++++++++++++++-
 2 files changed, 38 insertions(+), 2 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index e482b00f14d572..8965edbaf9b834 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -273,6 +273,7 @@ struct fuse4fs {
 	enum fuse4fs_feature_toggle iomap_want;
 	enum fuse4fs_iomap_state iomap_state;
 	uint32_t iomap_dev;
+	uint64_t iomap_cap;
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -1240,6 +1241,8 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
 	if (ff->directio)
 		flags |= EXT2_FLAG_DIRECT_IO;
 
+	dbg_printf(ff, "opening with flags=0x%x\n", flags);
+
 	err = ext2fs_open2(ff->device, options, flags, 0, 0, unix_io_manager,
 			   &ff->fs);
 	if (err == EPERM) {
@@ -6930,6 +6933,19 @@ static unsigned long long default_cache_size(void)
 	return ret;
 }
 
+#ifdef HAVE_FUSE_IOMAP
+static inline bool fuse4fs_discover_iomap(struct fuse4fs *ff)
+{
+	if (ff->iomap_want == FT_DISABLE)
+		return false;
+
+	ff->iomap_cap = fuse_lowlevel_discover_iomap(-1);
+	return ff->iomap_cap & FUSE_IOMAP_SUPPORT_FILEIO;
+}
+#else
+# define fuse4fs_discover_iomap(...)	(false)
+#endif
+
 static inline bool fuse4fs_want_fuseblk(const struct fuse4fs *ff)
 {
 	if (ff->noblkdev)
@@ -7071,6 +7087,7 @@ int main(int argc, char *argv[])
 	errcode_t err;
 	FILE *orig_stderr = stderr;
 	char extra_args[BUFSIZ];
+	bool iomap_detected = false;
 	int ret;
 
 	ret = fuse_opt_parse(&args, &fctx, fuse4fs_opts, fuse4fs_opt_proc);
@@ -7144,7 +7161,8 @@ int main(int argc, char *argv[])
 		goto out;
 	}
 
-	if (fuse4fs_want_fuseblk(&fctx)) {
+	iomap_detected = fuse4fs_discover_iomap(&fctx);
+	if (!iomap_detected && fuse4fs_want_fuseblk(&fctx)) {
 		/*
 		 * If this is a block device, we want to close the fs, reopen
 		 * the block device in non-exclusive mode, and start the fuse
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index c13bd6c3baf9c9..7fa4070dee0367 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -267,6 +267,7 @@ struct fuse2fs {
 	enum fuse2fs_feature_toggle iomap_want;
 	enum fuse2fs_iomap_state iomap_state;
 	uint32_t iomap_dev;
+	uint64_t iomap_cap;
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -1052,6 +1053,8 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff, int libext2_flags)
 	if (ff->directio)
 		flags |= EXT2_FLAG_DIRECT_IO;
 
+	dbg_printf(ff, "opening with flags=0x%x\n", flags);
+
 	err = ext2fs_open2(ff->device, options, flags, 0, 0, unix_io_manager,
 			   &ff->fs);
 	if (err == EPERM) {
@@ -6426,6 +6429,19 @@ static unsigned long long default_cache_size(void)
 	return ret;
 }
 
+#ifdef HAVE_FUSE_IOMAP
+static inline bool fuse2fs_discover_iomap(struct fuse2fs *ff)
+{
+	if (ff->iomap_want == FT_DISABLE)
+		return false;
+
+	ff->iomap_cap = fuse_lowlevel_discover_iomap(-1);
+	return ff->iomap_cap & FUSE_IOMAP_SUPPORT_FILEIO;
+}
+#else
+# define fuse2fs_discover_iomap(...)	(false)
+#endif
+
 static inline bool fuse2fs_want_fuseblk(const struct fuse2fs *ff)
 {
 	if (ff->noblkdev)
@@ -6466,6 +6482,7 @@ int main(int argc, char *argv[])
 	errcode_t err;
 	FILE *orig_stderr = stderr;
 	char extra_args[BUFSIZ];
+	bool iomap_detected = false;
 	int ret;
 
 	ret = fuse_opt_parse(&args, &fctx, fuse2fs_opts, fuse2fs_opt_proc);
@@ -6539,7 +6556,8 @@ int main(int argc, char *argv[])
 		goto out;
 	}
 
-	if (fuse2fs_want_fuseblk(&fctx)) {
+	iomap_detected = fuse2fs_discover_iomap(&fctx);
+	if (!iomap_detected && fuse2fs_want_fuseblk(&fctx)) {
 		/*
 		 * If this is a block device, we want to close the fs, reopen
 		 * the block device in non-exclusive mode, and start the fuse

[PATCH 12/17] fuse2fs: enable file IO to inline data files

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Enable file reads and writes from inline data files.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |    3 ++-
 misc/fuse2fs.c    |   42 ++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 42 insertions(+), 3 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 8965edbaf9b834..47ad8215c3e1d1 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -5925,7 +5925,8 @@ static int fuse4fs_iomap_begin_read(struct fuse4fs *ff, ext2_ino_t ino,
 {
 	/* fall back to slow path for inline data reads */
 	if (inode->i_flags & EXT4_INLINE_DATA_FL)
-		return -ENOSYS;
+		return fuse4fs_iomap_begin_inline(ff, ino, inode, pos, count,
+						  read);
 
 	if (inode->i_flags & EXT4_EXTENTS_FL)
 		return fuse4fs_iomap_begin_extent(ff, ino, inode, pos, count,
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 7fa4070dee0367..5dc0b0606112af 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1480,7 +1480,16 @@ static void *op_init(struct fuse_conn_info *conn,
 	cfg->use_ino = 1;
 	if (ff->debug)
 		cfg->debug = 1;
-	cfg->nullpath_ok = 1;
+
+	/*
+	 * Inline data file io depends on op_read/write being fed a path, so we
+	 * have to slow everyone down to look up the path from the nodeid.
+	 */
+	if (fuse2fs_iomap_enabled(ff) &&
+	    ext2fs_has_feature_inline_data(ff->fs->super))
+		cfg->nullpath_ok = 0;
+	else
+		cfg->nullpath_ok = 1;
 
 	if (ff->kernel) {
 		char uuid[UUID_STR_SIZE];
@@ -3412,6 +3421,9 @@ static int op_read(const char *path EXT2FS_ATTR((unused)), char *buf,
 		   size_t len, off_t offset,
 		   struct fuse_file_info *fp)
 {
+	struct fuse2fs_file_handle fhurk = {
+		.magic = FUSE2FS_FILE_MAGIC,
+	};
 	struct fuse2fs *ff = fuse2fs_get();
 	struct fuse2fs_file_handle *fh = fuse2fs_get_handle(fp);
 	ext2_filsys fs;
@@ -3421,10 +3433,21 @@ static int op_read(const char *path EXT2FS_ATTR((unused)), char *buf,
 	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
+
+	if (!fh)
+		fh = &fhurk;
+
 	FUSE2FS_CHECK_HANDLE(ff, fh);
 	dbg_printf(ff, "%s: ino=%d off=0x%llx len=0x%zx\n", __func__, fh->ino,
 		   (unsigned long long)offset, len);
 	fs = fuse2fs_start(ff);
+
+	if (fh == &fhurk) {
+		ret = fuse2fs_file_ino(ff, path, NULL, &fhurk.ino);
+		if (ret)
+			goto out;
+	}
+
 	err = ext2fs_file_open(fs, fh->ino, fh->open_flags, &efp);
 	if (err) {
 		ret = translate_error(fs, fh->ino, err);
@@ -3466,6 +3489,10 @@ static int op_write(const char *path EXT2FS_ATTR((unused)),
 		    const char *buf, size_t len, off_t offset,
 		    struct fuse_file_info *fp)
 {
+	struct fuse2fs_file_handle fhurk = {
+		.magic = FUSE2FS_FILE_MAGIC,
+		.open_flags = EXT2_FILE_WRITE,
+	};
 	struct fuse2fs *ff = fuse2fs_get();
 	struct fuse2fs_file_handle *fh = fuse2fs_get_handle(fp);
 	ext2_filsys fs;
@@ -3475,6 +3502,10 @@ static int op_write(const char *path EXT2FS_ATTR((unused)),
 	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
+
+	if (!fh)
+		fh = &fhurk;
+
 	FUSE2FS_CHECK_HANDLE(ff, fh);
 	dbg_printf(ff, "%s: ino=%d off=0x%llx len=0x%zx\n", __func__, fh->ino,
 		   (unsigned long long) offset, len);
@@ -3489,6 +3520,12 @@ static int op_write(const char *path EXT2FS_ATTR((unused)),
 		goto out;
 	}
 
+	if (fh == &fhurk) {
+		ret = fuse2fs_file_ino(ff, path, NULL, &fhurk.ino);
+		if (ret)
+			goto out;
+	}
+
 	err = ext2fs_file_open(fs, fh->ino, fh->open_flags, &efp);
 	if (err) {
 		ret = translate_error(fs, fh->ino, err);
@@ -5429,7 +5466,8 @@ static int fuse2fs_iomap_begin_read(struct fuse2fs *ff, ext2_ino_t ino,
 {
 	/* fall back to slow path for inline data reads */
 	if (inode->i_flags & EXT4_INLINE_DATA_FL)
-		return -ENOSYS;
+		return fuse2fs_iomap_begin_inline(ff, ino, inode, pos, count,
+						  read);
 
 	if (inode->i_flags & EXT4_EXTENTS_FL)
 		return fuse2fs_iomap_begin_extent(ff, ino, inode, pos, count,

[PATCH 13/17] fuse2fs: set iomap-related inode flags

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Set FUSE_IFLAG_* when we do a getattr, so that all files will have iomap
enabled.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   46 +++++++++++++++++++++++++++++++++++-----------
 misc/fuse2fs.c    |   20 ++++++++++++++++++++
 2 files changed, 55 insertions(+), 11 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 47ad8215c3e1d1..37999d864a05e5 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -1685,6 +1685,7 @@ static void op_init(void *userdata, struct fuse_conn_info *conn)
 
 struct fuse4fs_stat {
 	struct fuse_entry_param	entry;
+	unsigned int iflags;
 };
 
 static int fuse4fs_stat_inode(struct fuse4fs *ff, ext2_ino_t ino,
@@ -1750,9 +1751,29 @@ static int fuse4fs_stat_inode(struct fuse4fs *ff, ext2_ino_t ino,
 	entry->attr_timeout = FUSE4FS_ATTR_TIMEOUT;
 	entry->entry_timeout = FUSE4FS_ATTR_TIMEOUT;
 
+	fstat->iflags = 0;
+#ifdef HAVE_FUSE_IOMAP
+	if (fuse4fs_iomap_enabled(ff))
+		fstat->iflags |= FUSE_IFLAG_IOMAP;
+#endif
+
 	return 0;
 }
 
+#if FUSE_VERSION < FUSE_MAKE_VERSION(3, 99)
+#define fuse_reply_entry_iflags(req, entry, iflags) \
+	fuse_reply_entry((req), (entry))
+
+#define fuse_reply_attr_iflags(req, entry, iflags, timeout) \
+	fuse_reply_attr((req), (entry), (timeout))
+
+#define fuse_add_direntry_plus_iflags(req, buf, sz, name, iflags, entry, dirpos) \
+	fuse_add_direntry_plus((req), (buf), (sz), (name), (entry), (dirpos))
+
+#define fuse_reply_create_iflags(req, entry, iflags, fp) \
+	fuse_reply_create((req), (entry), (fp))
+#endif
+
 static void op_lookup(fuse_req_t req, fuse_ino_t fino, const char *name)
 {
 	struct fuse4fs_stat fstat;
@@ -1783,7 +1804,7 @@ static void op_lookup(fuse_req_t req, fuse_ino_t fino, const char *name)
 	if (ret)
 		fuse_reply_err(req, -ret);
 	else
-		fuse_reply_entry(req, &fstat.entry);
+		fuse_reply_entry_iflags(req, &fstat.entry, fstat.iflags);
 }
 
 static void op_getattr(fuse_req_t req, fuse_ino_t fino,
@@ -1803,8 +1824,8 @@ static void op_getattr(fuse_req_t req, fuse_ino_t fino,
 	if (ret)
 		fuse_reply_err(req, -ret);
 	else
-		fuse_reply_attr(req, &fstat.entry.attr,
-				fstat.entry.attr_timeout);
+		fuse_reply_attr_iflags(req, &fstat.entry.attr, fstat.iflags,
+				       fstat.entry.attr_timeout);
 }
 
 static void op_readlink(fuse_req_t req, fuse_ino_t fino)
@@ -2082,7 +2103,7 @@ static void fuse4fs_reply_entry(fuse_req_t req, ext2_ino_t ino,
 		return;
 	}
 
-	fuse_reply_entry(req, &fstat.entry);
+	fuse_reply_entry_iflags(req, &fstat.entry, fstat.iflags);
 }
 
 static void op_mknod(fuse_req_t req, fuse_ino_t fino, const char *name,
@@ -4352,10 +4373,13 @@ static int op_readdir_iter(ext2_ino_t dir EXT2FS_ATTR((unused)),
 	namebuf[dirent->name_len & 0xFF] = 0;
 
 	if (i->readdirplus) {
-		entrysize = fuse_add_direntry_plus(i->req, i->buf + i->bufused,
-						   i->bufsz - i->bufused,
-						   namebuf, &fstat.entry,
-						   i->dirpos);
+		entrysize = fuse_add_direntry_plus_iflags(i->req,
+							  i->buf + i->bufused,
+							  i->bufsz - i->bufused,
+							  namebuf,
+							  fstat.iflags,
+							  &fstat.entry,
+							  i->dirpos);
 	} else {
 		entrysize = fuse_add_direntry(i->req, i->buf + i->bufused,
 					      i->bufsz - i->bufused, namebuf,
@@ -4580,7 +4604,7 @@ static void op_create(fuse_req_t req, fuse_ino_t fino, const char *name,
 	if (ret)
 		fuse_reply_err(req, -ret);
 	else
-		fuse_reply_create(req, &fstat.entry, fp);
+		fuse_reply_create_iflags(req, &fstat.entry, fstat.iflags, fp);
 }
 
 #if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 17)
@@ -4779,8 +4803,8 @@ static void op_setattr(fuse_req_t req, fuse_ino_t fino, struct stat *attr,
 	if (ret)
 		fuse_reply_err(req, -ret);
 	else
-		fuse_reply_attr(req, &fstat.entry.attr,
-				fstat.entry.attr_timeout);
+		fuse_reply_attr_iflags(req, &fstat.entry.attr, fstat.iflags,
+				       fstat.entry.attr_timeout);
 }
 
 #define FUSE4FS_MODIFIABLE_IFLAGS \
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 5dc0b0606112af..32fcada0426752 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1619,6 +1619,23 @@ static int op_getattr(const char *path, struct stat *statbuf,
 	return ret;
 }
 
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
+static int op_getattr_iflags(const char *path, struct stat *statbuf,
+			     unsigned int *iflags, struct fuse_file_info *fi)
+{
+	int ret = op_getattr(path, statbuf, fi);
+
+	if (ret)
+		return ret;
+
+	if (fuse_fs_can_enable_iomap(statbuf))
+		*iflags |= FUSE_IFLAG_IOMAP;
+
+	return 0;
+}
+#endif
+
+
 static int op_readlink(const char *path, char *buf, size_t len)
 {
 	struct fuse2fs *ff = fuse2fs_get();
@@ -6238,6 +6255,9 @@ static struct fuse_operations fs_ops = {
 #ifdef SUPPORT_FALLOCATE
 	.fallocate = op_fallocate,
 #endif
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
+	.getattr_iflags = op_getattr_iflags,
+#endif
 #ifdef HAVE_FUSE_IOMAP
 	.iomap_begin = op_iomap_begin,
 	.iomap_end = op_iomap_end,

[PATCH 14/17] fuse2fs: configure block device block size

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Set the blocksize of the block device to the filesystem blocksize.
This prevents the bdev pagecache from caching file data blocks that
iomap will read and write directly.  Cache duplication is dangerous.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   43 +++++++++++++++++++++++++++++++++++++++++++
 misc/fuse2fs.c    |   43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 37999d864a05e5..6f3ddceea85c27 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -6247,6 +6247,45 @@ static off_t fuse4fs_max_size(struct fuse4fs *ff, off_t upper_limit)
 	return res;
 }
 
+/*
+ * Set the block device's blocksize to the fs blocksize.
+ *
+ * This is required to avoid creating uptodate bdev pagecache that aliases file
+ * data blocks because iomap reads and writes directly to file data blocks.
+ */
+static int fuse4fs_set_bdev_blocksize(struct fuse4fs *ff, int fd)
+{
+	int blocksize = ff->fs->blocksize;
+	int set_error;
+	int ret;
+
+	ret = ioctl(fd, BLKBSZSET, &blocksize);
+	if (!ret)
+		return 0;
+
+	/*
+	 * Save the original errno so we can report that if the block device
+	 * blocksize isn't set in an agreeable way.
+	 */
+	set_error = errno;
+
+	ret = ioctl(fd, BLKBSZGET, &blocksize);
+	if (ret)
+		goto out_bad;
+
+	/* Pretend that BLKBSZSET rejected our proposed block size */
+	if (blocksize > ff->fs->blocksize) {
+		set_error = EINVAL;
+		goto out_bad;
+	}
+
+	return 0;
+out_bad:
+	err_printf(ff, "%s: cannot set blocksize %u: %s\n", __func__,
+		   blocksize, strerror(set_error));
+	return -EIO;
+}
+
 static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)
 {
 	errcode_t err;
@@ -6257,6 +6296,10 @@ static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)
 	if (err)
 		return translate_error(ff->fs, 0, err);
 
+	ret = fuse4fs_set_bdev_blocksize(ff, fd);
+	if (ret)
+		return ret;
+
 	ret = fuse_lowlevel_iomap_device_add(ff->fuse, fd, 0);
 	if (ret < 0) {
 		dbg_printf(ff, "%s: cannot register iomap dev fd=%d, err=%d\n",
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 32fcada0426752..9212235495dc22 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -5777,6 +5777,45 @@ static off_t fuse2fs_max_size(struct fuse2fs *ff, off_t upper_limit)
 	return res;
 }
 
+/*
+ * Set the block device's blocksize to the fs blocksize.
+ *
+ * This is required to avoid creating uptodate bdev pagecache that aliases file
+ * data blocks because iomap reads and writes directly to file data blocks.
+ */
+static int fuse2fs_set_bdev_blocksize(struct fuse2fs *ff, int fd)
+{
+	int blocksize = ff->fs->blocksize;
+	int set_error;
+	int ret;
+
+	ret = ioctl(fd, BLKBSZSET, &blocksize);
+	if (!ret)
+		return 0;
+
+	/*
+	 * Save the original errno so we can report that if the block device
+	 * blocksize isn't set in an agreeable way.
+	 */
+	set_error = errno;
+
+	ret = ioctl(fd, BLKBSZGET, &blocksize);
+	if (ret)
+		goto out_bad;
+
+	/* Pretend that BLKBSZSET rejected our proposed block size */
+	if (blocksize > ff->fs->blocksize) {
+		set_error = EINVAL;
+		goto out_bad;
+	}
+
+	return 0;
+out_bad:
+	err_printf(ff, "%s: cannot set blocksize %u: %s\n", __func__,
+		   blocksize, strerror(set_error));
+	return -EIO;
+}
+
 static int fuse2fs_iomap_config_devices(struct fuse2fs *ff)
 {
 	errcode_t err;
@@ -5787,6 +5826,10 @@ static int fuse2fs_iomap_config_devices(struct fuse2fs *ff)
 	if (err)
 		return translate_error(ff->fs, 0, err);
 
+	ret = fuse2fs_set_bdev_blocksize(ff, fd);
+	if (ret)
+		return ret;
+
 	ret = fuse_fs_iomap_device_add(fd, 0);
 	if (ret < 0) {
 		dbg_printf(ff, "%s: cannot register iomap dev fd=%d, err=%d\n",

[PATCH 15/17] fuse4fs: separate invalidation

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Use the new stuff

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   61 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 misc/fuse2fs.c    |   60 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 121 insertions(+)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 6f3ddceea85c27..c633bb9eca068a 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -274,6 +274,9 @@ struct fuse4fs {
 	enum fuse4fs_iomap_state iomap_state;
 	uint32_t iomap_dev;
 	uint64_t iomap_cap;
+	void (*old_alloc_stats)(ext2_filsys fs, blk64_t blk, int inuse);
+	void (*old_alloc_stats_range)(ext2_filsys fs, blk64_t blk, blk_t num,
+				      int inuse);
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -6314,6 +6317,51 @@ static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)
 	return 0;
 }
 
+static void fuse4fs_invalidate_bdev(struct fuse4fs *ff, blk64_t blk, blk_t num)
+{
+	off_t offset = FUSE4FS_FSB_TO_B(ff, blk);
+	off_t length = FUSE4FS_FSB_TO_B(ff, num);
+	int ret;
+
+	ret = fuse_lowlevel_iomap_device_invalidate(ff->fuse, ff->iomap_dev,
+						    offset, length);
+	if (!ret)
+		return;
+
+	if (num == 1)
+		err_printf(ff, "%s %llu: %s\n",
+			   _("error invalidating block"),
+			   (unsigned long long)blk,
+			   strerror(ret));
+	else
+		err_printf(ff, "%s %llu-%llu: %s\n",
+			   _("error invalidating blocks"),
+			   (unsigned long long)blk,
+			   (unsigned long long)blk + num - 1,
+			   strerror(ret));
+}
+
+static void fuse4fs_alloc_stats(ext2_filsys fs, blk64_t blk, int inuse)
+{
+	struct fuse4fs *ff = fs->priv_data;
+
+	if (inuse < 0)
+		fuse4fs_invalidate_bdev(ff, blk, 1);
+	if (ff->old_alloc_stats)
+		ff->old_alloc_stats(fs, blk, inuse);
+}
+
+static void fuse4fs_alloc_stats_range(ext2_filsys fs, blk64_t blk, blk_t num,
+				      int inuse)
+{
+	struct fuse4fs *ff = fs->priv_data;
+
+	if (inuse < 0)
+		fuse4fs_invalidate_bdev(ff, blk, num);
+	if (ff->old_alloc_stats_range)
+		ff->old_alloc_stats_range(fs, blk, num, inuse);
+}
+
 static void op_iomap_config(fuse_req_t req, uint64_t flags, uint64_t maxbytes)
 {
 	struct fuse_iomap_config cfg = { };
@@ -6358,6 +6406,19 @@ static void op_iomap_config(fuse_req_t req, uint64_t flags, uint64_t maxbytes)
 	if (ret)
 		goto out_unlock;
 
+	/*
+	 * If we let iomap do all file block IO, then we need to watch for
+	 * freed blocks so that we can invalidate any page cache that might
+	 * get written to the block deivce.
+	 */
+	if (fuse4fs_iomap_enabled(ff)) {
+		ext2fs_set_block_alloc_stats_callback(ff->fs,
+				fuse4fs_alloc_stats, &ff->old_alloc_stats);
+		ext2fs_set_block_alloc_stats_range_callback(ff->fs,
+				fuse4fs_alloc_stats_range,
+				&ff->old_alloc_stats_range);
+	}
+
 out_unlock:
 	fuse4fs_finish(ff, ret);
 	if (ret)
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 9212235495dc22..1567c2e72279c2 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -268,6 +268,9 @@ struct fuse2fs {
 	enum fuse2fs_iomap_state iomap_state;
 	uint32_t iomap_dev;
 	uint64_t iomap_cap;
+	void (*old_alloc_stats)(ext2_filsys fs, blk64_t blk, int inuse);
+	void (*old_alloc_stats_range)(ext2_filsys fs, blk64_t blk, blk_t num,
+				      int inuse);
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -5844,6 +5847,50 @@ static int fuse2fs_iomap_config_devices(struct fuse2fs *ff)
 	return 0;
 }
 
+static void fuse2fs_invalidate_bdev(struct fuse2fs *ff, blk64_t blk, blk_t num)
+{
+	off_t offset = FUSE2FS_FSB_TO_B(ff, blk);
+	off_t length = FUSE2FS_FSB_TO_B(ff, num);
+	int ret;
+
+	ret = fuse_fs_iomap_device_invalidate(ff->iomap_dev, offset, length);
+	if (!ret)
+		return;
+
+	if (num == 1)
+		err_printf(ff, "%s %llu: %s\n",
+			   _("error invalidating block"),
+			   (unsigned long long)blk,
+			   strerror(ret));
+	else
+		err_printf(ff, "%s %llu-%llu: %s\n",
+			   _("error invalidating blocks"),
+			   (unsigned long long)blk,
+			   (unsigned long long)blk + num - 1,
+			   strerror(ret));
+}
+
+static void fuse2fs_alloc_stats(ext2_filsys fs, blk64_t blk, int inuse)
+{
+	struct fuse2fs *ff = fs->priv_data;
+
+	if (inuse < 0)
+		fuse2fs_invalidate_bdev(ff, blk, 1);
+	if (ff->old_alloc_stats)
+		ff->old_alloc_stats(fs, blk, inuse);
+}
+
+static void fuse2fs_alloc_stats_range(ext2_filsys fs, blk64_t blk, blk_t num,
+				      int inuse)
+{
+	struct fuse2fs *ff = fs->priv_data;
+
+	if (inuse < 0)
+		fuse2fs_invalidate_bdev(ff, blk, num);
+	if (ff->old_alloc_stats_range)
+		ff->old_alloc_stats_range(fs, blk, num, inuse);
+}
+
 static int op_iomap_config(uint64_t flags, off_t maxbytes,
 			   struct fuse_iomap_config *cfg)
 {
@@ -5888,6 +5935,19 @@ static int op_iomap_config(uint64_t flags, off_t maxbytes,
 	if (ret)
 		goto out_unlock;
 
+	/*
+	 * If we let iomap do all file block IO, then we need to watch for
+	 * freed blocks so that we can invalidate any page cache that might
+	 * get written to the block deivce.
+	 */
+	if (fuse2fs_iomap_enabled(ff)) {
+		ext2fs_set_block_alloc_stats_callback(ff->fs,
+				fuse2fs_alloc_stats, &ff->old_alloc_stats);
+		ext2fs_set_block_alloc_stats_range_callback(ff->fs,
+				fuse2fs_alloc_stats_range,
+				&ff->old_alloc_stats_range);
+	}
+
 out_unlock:
 	fuse2fs_finish(ff, ret);
 	return ret;

[PATCH 16/17] fuse2fs: implement statx

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Implement statx.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |  133 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 misc/fuse2fs.c    |  128 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 261 insertions(+)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index c633bb9eca068a..6c3e2992a04211 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -24,6 +24,7 @@
 #include <sys/xattr.h>
 #endif
 #include <sys/ioctl.h>
+#include <sys/sysmacros.h>
 #include <unistd.h>
 #include <ctype.h>
 #include <stdbool.h>
@@ -1831,6 +1832,135 @@ static void op_getattr(fuse_req_t req, fuse_ino_t fino,
 				       fstat.entry.attr_timeout);
 }
 
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 18) && defined(STATX_BASIC_STATS)
+static inline void fuse4fs_set_statx_attr(struct statx *stx,
+					  uint64_t statx_flag, int set)
+{
+	if (set)
+		stx->stx_attributes |= statx_flag;
+	stx->stx_attributes_mask |= statx_flag;
+}
+
+static void fuse4fs_statx_directio(struct fuse4fs *ff, struct statx *stx)
+{
+	struct statx devx;
+	errcode_t err;
+	int fd;
+
+	err = io_channel_get_fd(ff->fs->io, &fd);
+	if (err)
+		return;
+
+	err = statx(fd, "", AT_EMPTY_PATH, STATX_DIOALIGN, &devx);
+	if (err)
+		return;
+	if (!(devx.stx_mask & STATX_DIOALIGN))
+		return;
+
+	stx->stx_mask |= STATX_DIOALIGN;
+	stx->stx_dio_mem_align = devx.stx_dio_mem_align;
+	stx->stx_dio_offset_align = devx.stx_dio_offset_align;
+}
+
+static int fuse4fs_statx(struct fuse4fs *ff, ext2_ino_t ino, int statx_mask,
+			 struct statx *stx)
+{
+	struct ext2_inode_large inode;
+	ext2_filsys fs = ff->fs;;
+	dev_t fakedev = 0;
+	errcode_t err;
+	struct timespec tv;
+
+	err = fuse4fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	memcpy(&fakedev, fs->super->s_uuid, sizeof(fakedev));
+	stx->stx_mask = STATX_BASIC_STATS | STATX_BTIME;
+	stx->stx_dev_major = major(fakedev);
+	stx->stx_dev_minor = minor(fakedev);
+	stx->stx_ino = ino;
+	stx->stx_mode = inode.i_mode;
+	stx->stx_nlink = inode.i_links_count;
+	stx->stx_uid = inode_uid(inode);
+	stx->stx_gid = inode_gid(inode);
+	stx->stx_size = EXT2_I_SIZE(&inode);
+	stx->stx_blksize = fs->blocksize;
+	stx->stx_blocks = ext2fs_get_stat_i_blocks(fs,
+						EXT2_INODE(&inode));
+	EXT4_INODE_GET_XTIME(i_atime, &tv, &inode);
+	stx->stx_atime.tv_sec = tv.tv_sec;
+	stx->stx_atime.tv_nsec = tv.tv_nsec;
+
+	EXT4_INODE_GET_XTIME(i_mtime, &tv, &inode);
+	stx->stx_mtime.tv_sec = tv.tv_sec;
+	stx->stx_mtime.tv_nsec = tv.tv_nsec;
+
+	EXT4_INODE_GET_XTIME(i_ctime, &tv, &inode);
+	stx->stx_ctime.tv_sec = tv.tv_sec;
+	stx->stx_ctime.tv_nsec = tv.tv_nsec;
+
+	EXT4_INODE_GET_XTIME(i_crtime, &tv, &inode);
+	stx->stx_btime.tv_sec = tv.tv_sec;
+	stx->stx_btime.tv_nsec = tv.tv_nsec;
+
+	dbg_printf(ff, "%s: ino=%d atime=%lld.%d mtime=%lld.%d ctime=%lld.%d btime=%lld.%d\n",
+		   __func__, ino,
+		   (long long int)stx->stx_atime.tv_sec, stx->stx_atime.tv_nsec,
+		   (long long int)stx->stx_mtime.tv_sec, stx->stx_mtime.tv_nsec,
+		   (long long int)stx->stx_ctime.tv_sec, stx->stx_ctime.tv_nsec,
+		   (long long int)stx->stx_btime.tv_sec, stx->stx_btime.tv_nsec);
+
+	if (LINUX_S_ISCHR(inode.i_mode) ||
+	    LINUX_S_ISBLK(inode.i_mode)) {
+		if (inode.i_block[0]) {
+			stx->stx_rdev_major = major(inode.i_block[0]);
+			stx->stx_rdev_minor = minor(inode.i_block[0]);
+		} else {
+			stx->stx_rdev_major = major(inode.i_block[1]);
+			stx->stx_rdev_minor = minor(inode.i_block[1]);
+		}
+	}
+
+	fuse4fs_set_statx_attr(stx, STATX_ATTR_COMPRESSED,
+			       inode.i_flags & EXT2_COMPR_FL);
+	fuse4fs_set_statx_attr(stx, STATX_ATTR_IMMUTABLE,
+			       inode.i_flags & EXT2_IMMUTABLE_FL);
+	fuse4fs_set_statx_attr(stx, STATX_ATTR_APPEND,
+			       inode.i_flags & EXT2_APPEND_FL);
+	fuse4fs_set_statx_attr(stx, STATX_ATTR_NODUMP,
+			       inode.i_flags & EXT2_NODUMP_FL);
+
+	fuse4fs_statx_directio(ff, stx);
+
+	return 0;
+}
+
+static void op_statx(fuse_req_t req, fuse_ino_t fino, int flags, int mask,
+		     struct fuse_file_info *fi)
+{
+	struct statx stx;
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_ino_t ino;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	FUSE4FS_CONVERT_FINO(req, &ino, fino);
+	fuse4fs_start(ff);
+	ret = fuse4fs_statx(ff, ino, mask, &stx);
+	if (ret)
+		goto out;
+out:
+	fuse4fs_finish(ff, ret);
+	if (ret)
+		fuse_reply_err(req, -ret);
+	else
+		fuse_reply_statx(req, 0, &stx, FUSE4FS_ATTR_TIMEOUT);
+}
+#else
+# define op_statx		NULL
+#endif
+
 static void op_readlink(fuse_req_t req, fuse_ino_t fino)
 {
 	struct ext2_inode inode;
@@ -6834,6 +6964,9 @@ static struct fuse_lowlevel_ops fs_ops = {
 #ifdef SUPPORT_FALLOCATE
 	.fallocate = op_fallocate,
 #endif
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 18)
+	.statx = op_statx,
+#endif
 #ifdef HAVE_FUSE_IOMAP
 	.iomap_begin = op_iomap_begin,
 	.iomap_end = op_iomap_end,
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 1567c2e72279c2..d6bf7357653acd 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -23,6 +23,7 @@
 #include <sys/xattr.h>
 #endif
 #include <sys/ioctl.h>
+#include <sys/sysmacros.h>
 #include <unistd.h>
 #include <ctype.h>
 #include <stdbool.h>
@@ -1638,6 +1639,130 @@ static int op_getattr_iflags(const char *path, struct stat *statbuf,
 }
 #endif
 
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 18) && defined(STATX_BASIC_STATS)
+static inline void fuse2fs_set_statx_attr(struct statx *stx,
+					  uint64_t statx_flag, int set)
+{
+	if (set)
+		stx->stx_attributes |= statx_flag;
+	stx->stx_attributes_mask |= statx_flag;
+}
+
+static void fuse2fs_statx_directio(struct fuse2fs *ff, struct statx *stx)
+{
+	struct statx devx;
+	errcode_t err;
+	int fd;
+
+	err = io_channel_get_fd(ff->fs->io, &fd);
+	if (err)
+		return;
+
+	err = statx(fd, "", AT_EMPTY_PATH, STATX_DIOALIGN, &devx);
+	if (err)
+		return;
+	if (!(devx.stx_mask & STATX_DIOALIGN))
+		return;
+
+	stx->stx_mask |= STATX_DIOALIGN;
+	stx->stx_dio_mem_align = devx.stx_dio_mem_align;
+	stx->stx_dio_offset_align = devx.stx_dio_offset_align;
+}
+
+static int fuse2fs_statx(struct fuse2fs *ff, ext2_ino_t ino, int statx_mask,
+			 struct statx *stx)
+{
+	struct ext2_inode_large inode;
+	ext2_filsys fs = ff->fs;;
+	dev_t fakedev = 0;
+	errcode_t err;
+	struct timespec tv;
+
+	err = fuse2fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	memcpy(&fakedev, fs->super->s_uuid, sizeof(fakedev));
+	stx->stx_mask = STATX_BASIC_STATS | STATX_BTIME;
+	stx->stx_dev_major = major(fakedev);
+	stx->stx_dev_minor = minor(fakedev);
+	stx->stx_ino = ino;
+	stx->stx_mode = inode.i_mode;
+	stx->stx_nlink = inode.i_links_count;
+	stx->stx_uid = inode_uid(inode);
+	stx->stx_gid = inode_gid(inode);
+	stx->stx_size = EXT2_I_SIZE(&inode);
+	stx->stx_blksize = fs->blocksize;
+	stx->stx_blocks = ext2fs_get_stat_i_blocks(fs,
+						EXT2_INODE(&inode));
+	EXT4_INODE_GET_XTIME(i_atime, &tv, &inode);
+	stx->stx_atime.tv_sec = tv.tv_sec;
+	stx->stx_atime.tv_nsec = tv.tv_nsec;
+
+	EXT4_INODE_GET_XTIME(i_mtime, &tv, &inode);
+	stx->stx_mtime.tv_sec = tv.tv_sec;
+	stx->stx_mtime.tv_nsec = tv.tv_nsec;
+
+	EXT4_INODE_GET_XTIME(i_ctime, &tv, &inode);
+	stx->stx_ctime.tv_sec = tv.tv_sec;
+	stx->stx_ctime.tv_nsec = tv.tv_nsec;
+
+	EXT4_INODE_GET_XTIME(i_crtime, &tv, &inode);
+	stx->stx_btime.tv_sec = tv.tv_sec;
+	stx->stx_btime.tv_nsec = tv.tv_nsec;
+
+	dbg_printf(ff, "%s: ino=%d atime=%lld.%d mtime=%lld.%d ctime=%lld.%d btime=%lld.%d\n",
+		   __func__, ino,
+		   (long long int)stx->stx_atime.tv_sec, stx->stx_atime.tv_nsec,
+		   (long long int)stx->stx_mtime.tv_sec, stx->stx_mtime.tv_nsec,
+		   (long long int)stx->stx_ctime.tv_sec, stx->stx_ctime.tv_nsec,
+		   (long long int)stx->stx_btime.tv_sec, stx->stx_btime.tv_nsec);
+
+	if (LINUX_S_ISCHR(inode.i_mode) ||
+	    LINUX_S_ISBLK(inode.i_mode)) {
+		if (inode.i_block[0]) {
+			stx->stx_rdev_major = major(inode.i_block[0]);
+			stx->stx_rdev_minor = minor(inode.i_block[0]);
+		} else {
+			stx->stx_rdev_major = major(inode.i_block[1]);
+			stx->stx_rdev_minor = minor(inode.i_block[1]);
+		}
+	}
+
+	fuse2fs_set_statx_attr(stx, STATX_ATTR_COMPRESSED,
+			       inode.i_flags & EXT2_COMPR_FL);
+	fuse2fs_set_statx_attr(stx, STATX_ATTR_IMMUTABLE,
+			       inode.i_flags & EXT2_IMMUTABLE_FL);
+	fuse2fs_set_statx_attr(stx, STATX_ATTR_APPEND,
+			       inode.i_flags & EXT2_APPEND_FL);
+	fuse2fs_set_statx_attr(stx, STATX_ATTR_NODUMP,
+			       inode.i_flags & EXT2_NODUMP_FL);
+
+	fuse2fs_statx_directio(ff, stx);
+
+	return 0;
+}
+
+static int op_statx(const char *path, int statx_flags, int statx_mask,
+		    struct statx *stx, struct fuse_file_info *fi)
+{
+	struct fuse2fs *ff = fuse2fs_get();
+	ext2_ino_t ino;
+	int ret = 0;
+
+	FUSE2FS_CHECK_CONTEXT(ff);
+	fuse2fs_start(ff);
+	ret = fuse2fs_file_ino(ff, path, fi, &ino);
+	if (ret)
+		goto out;
+	ret = fuse2fs_statx(ff, ino, statx_mask, stx);
+out:
+	fuse2fs_finish(ff, ret);
+	return ret;
+}
+#else
+# define op_statx		NULL
+#endif
 
 static int op_readlink(const char *path, char *buf, size_t len)
 {
@@ -6358,6 +6483,9 @@ static struct fuse_operations fs_ops = {
 #ifdef SUPPORT_FALLOCATE
 	.fallocate = op_fallocate,
 #endif
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 18)
+	.statx = op_statx,
+#endif
 #if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
 	.getattr_iflags = op_getattr_iflags,
 #endif

[PATCH 17/17] fuse2fs: enable atomic writes

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Advertise the single-fsblock atomic write capability that iomap can do.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   67 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 misc/fuse2fs.c    |   68 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 133 insertions(+), 2 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 6c3e2992a04211..abbc67bccef786 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -278,6 +278,9 @@ struct fuse4fs {
 	void (*old_alloc_stats)(ext2_filsys fs, blk64_t blk, int inuse);
 	void (*old_alloc_stats_range)(ext2_filsys fs, blk64_t blk, blk_t num,
 				      int inuse);
+#ifdef STATX_WRITE_ATOMIC
+	unsigned int awu_min, awu_max;
+#endif
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -736,8 +739,20 @@ static inline int fuse4fs_iomap_enabled(const struct fuse4fs *ff)
 {
 	return ff->iomap_state >= IOMAP_ENABLED;
 }
+
+static inline int fuse4fs_iomap_can_hw_atomic(const struct fuse4fs *ff)
+{
+	return fuse4fs_iomap_enabled(ff) &&
+	       (ff->iomap_cap & FUSE_IOMAP_SUPPORT_ATOMIC) &&
+#ifdef STATX_WRITE_ATOMIC
+		ff->awu_min > 0 && ff->awu_min > 0;
+#else
+		0;
+#endif
+}
 #else
 # define fuse4fs_iomap_enabled(...)	(0)
+# define fuse4fs_iomap_can_hw_atomic(...)	(0)
 #endif
 
 static inline void fuse4fs_dump_extents(struct fuse4fs *ff, ext2_ino_t ino,
@@ -1757,8 +1772,12 @@ static int fuse4fs_stat_inode(struct fuse4fs *ff, ext2_ino_t ino,
 
 	fstat->iflags = 0;
 #ifdef HAVE_FUSE_IOMAP
-	if (fuse4fs_iomap_enabled(ff))
+	if (fuse4fs_iomap_enabled(ff)) {
 		fstat->iflags |= FUSE_IFLAG_IOMAP;
+
+		if (fuse4fs_iomap_can_hw_atomic(ff))
+			fstat->iflags |= FUSE_IFLAG_ATOMIC;
+	}
 #endif
 
 	return 0;
@@ -1933,6 +1952,15 @@ static int fuse4fs_statx(struct fuse4fs *ff, ext2_ino_t ino, int statx_mask,
 
 	fuse4fs_statx_directio(ff, stx);
 
+#ifdef STATX_WRITE_ATOMIC
+	if (fuse4fs_iomap_can_hw_atomic(ff)) {
+		stx->stx_mask |= STATX_WRITE_ATOMIC;
+		stx->stx_atomic_write_unit_min = ff->awu_min;
+		stx->stx_atomic_write_unit_max = ff->awu_max;
+		stx->stx_atomic_write_segments_max = 1;
+	}
+#endif
+
 	return 0;
 }
 
@@ -6255,6 +6283,9 @@ static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 		}
 	}
 
+	if (opflags & FUSE_IOMAP_OP_ATOMIC)
+		read.flags |= FUSE_IOMAP_F_ATOMIC_BIO;
+
 out_unlock:
 	fuse4fs_finish(ff, ret);
 	if (ret)
@@ -6419,6 +6450,38 @@ static int fuse4fs_set_bdev_blocksize(struct fuse4fs *ff, int fd)
 	return -EIO;
 }
 
+#ifdef STATX_WRITE_ATOMIC
+static void fuse4fs_configure_atomic_write(struct fuse4fs *ff, int bdev_fd)
+{
+	struct statx devx;
+	unsigned int awu_min, awu_max;
+	int ret;
+
+	if (!ext2fs_has_feature_extents(ff->fs->super))
+		return;
+
+	ret = statx(bdev_fd, "", AT_EMPTY_PATH, STATX_WRITE_ATOMIC, &devx);
+	if (ret)
+		return;
+	if (!(devx.stx_mask & STATX_WRITE_ATOMIC))
+		return;
+
+	awu_min = max(ff->fs->blocksize, devx.stx_atomic_write_unit_min);
+	awu_max = min(ff->fs->blocksize, devx.stx_atomic_write_unit_max);
+	if (awu_min > awu_max)
+		return;
+
+	log_printf(ff, "%s awu_min: %u, awu_max: %u\n",
+		   _("Supports (experimental) DIO atomic writes"),
+		   awu_min, awu_max);
+
+	ff->awu_min = awu_min;
+	ff->awu_max = awu_max;
+}
+#else
+# define fuse4fs_configure_atomic_write(...)	((void)0)
+#endif
+
 static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)
 {
 	errcode_t err;
@@ -6443,6 +6506,8 @@ static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)
 	dbg_printf(ff, "%s: registered iomap dev fd=%d iomap_dev=%u\n",
 		   __func__, fd, ff->iomap_dev);
 
+	fuse4fs_configure_atomic_write(ff, fd);
+
 	ff->iomap_dev = ret;
 	return 0;
 }
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index d6bf7357653acd..0832a758bdad79 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -272,6 +272,9 @@ struct fuse2fs {
 	void (*old_alloc_stats)(ext2_filsys fs, blk64_t blk, int inuse);
 	void (*old_alloc_stats_range)(ext2_filsys fs, blk64_t blk, blk_t num,
 				      int inuse);
+#ifdef STATX_WRITE_ATOMIC
+	unsigned int awu_min, awu_max;
+#endif
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -573,9 +576,21 @@ static inline int fuse2fs_iomap_enabled(const struct fuse2fs *ff)
 {
 	return ff->iomap_state >= IOMAP_ENABLED;
 }
+
+static inline int fuse2fs_iomap_can_hw_atomic(const struct fuse2fs *ff)
+{
+	return fuse2fs_iomap_enabled(ff) &&
+	       (ff->iomap_cap & FUSE_IOMAP_SUPPORT_ATOMIC) &&
+#ifdef STATX_WRITE_ATOMIC
+		ff->awu_min > 0 && ff->awu_min > 0;
+#else
+		0;
+#endif
+}
 #else
 # define fuse2fs_iomap_enabled(...)	(0)
 # define fuse2fs_iomap_enabled(...)	(0)
+# define fuse2fs_iomap_can_hw_atomic(...)	(0)
 #endif
 
 static inline void fuse2fs_dump_extents(struct fuse2fs *ff, ext2_ino_t ino,
@@ -1627,14 +1642,19 @@ static int op_getattr(const char *path, struct stat *statbuf,
 static int op_getattr_iflags(const char *path, struct stat *statbuf,
 			     unsigned int *iflags, struct fuse_file_info *fi)
 {
+	struct fuse2fs *ff = fuse2fs_get();
 	int ret = op_getattr(path, statbuf, fi);
 
 	if (ret)
 		return ret;
 
-	if (fuse_fs_can_enable_iomap(statbuf))
+	if (fuse_fs_can_enable_iomap(statbuf)) {
 		*iflags |= FUSE_IFLAG_IOMAP;
 
+		if (fuse2fs_iomap_can_hw_atomic(ff))
+			*iflags |= FUSE_IFLAG_ATOMIC;
+	}
+
 	return 0;
 }
 #endif
@@ -1740,6 +1760,15 @@ static int fuse2fs_statx(struct fuse2fs *ff, ext2_ino_t ino, int statx_mask,
 
 	fuse2fs_statx_directio(ff, stx);
 
+#ifdef STATX_WRITE_ATOMIC
+	if (fuse_fs_can_enable_iomapx(stx) && fuse2fs_iomap_can_hw_atomic(ff)) {
+		stx->stx_mask |= STATX_WRITE_ATOMIC;
+		stx->stx_atomic_write_unit_min = ff->awu_min;
+		stx->stx_atomic_write_unit_max = ff->awu_max;
+		stx->stx_atomic_write_segments_max = 1;
+	}
+#endif
+
 	return 0;
 }
 
@@ -5783,6 +5812,9 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 		}
 	}
 
+	if (opflags & FUSE_IOMAP_OP_ATOMIC)
+		read->flags |= FUSE_IOMAP_F_ATOMIC_BIO;
+
 out_unlock:
 	fuse2fs_finish(ff, ret);
 	return ret;
@@ -5944,6 +5976,38 @@ static int fuse2fs_set_bdev_blocksize(struct fuse2fs *ff, int fd)
 	return -EIO;
 }
 
+#ifdef STATX_WRITE_ATOMIC
+static void fuse2fs_configure_atomic_write(struct fuse2fs *ff, int bdev_fd)
+{
+	struct statx devx;
+	unsigned int awu_min, awu_max;
+	int ret;
+
+	if (!ext2fs_has_feature_extents(ff->fs->super))
+		return;
+
+	ret = statx(bdev_fd, "", AT_EMPTY_PATH, STATX_WRITE_ATOMIC, &devx);
+	if (ret)
+		return;
+	if (!(devx.stx_mask & STATX_WRITE_ATOMIC))
+		return;
+
+	awu_min = max(ff->fs->blocksize, devx.stx_atomic_write_unit_min);
+	awu_max = min(ff->fs->blocksize, devx.stx_atomic_write_unit_max);
+	if (awu_min > awu_max)
+		return;
+
+	log_printf(ff, "%s awu_min: %u, awu_max: %u\n",
+		   _("Supports (experimental) DIO atomic writes"),
+		   awu_min, awu_max);
+
+	ff->awu_min = awu_min;
+	ff->awu_max = awu_max;
+}
+#else
+# define fuse2fs_configure_atomic_write(...)	((void)0)
+#endif
+
 static int fuse2fs_iomap_config_devices(struct fuse2fs *ff)
 {
 	errcode_t err;
@@ -5968,6 +6032,8 @@ static int fuse2fs_iomap_config_devices(struct fuse2fs *ff)
 	dbg_printf(ff, "%s: registered iomap dev fd=%d iomap_dev=%u\n",
 		   __func__, fd, ff->iomap_dev);
 
+	fuse2fs_configure_atomic_write(ff, fd);
+
 	ff->iomap_dev = ret;
 	return 0;
 }

[PATCH 1/1] fuse4fs: don't use inode number translation when possible

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Prior to the integration of iomap into fuse, the fuse client (aka the
kernel) required that the root directory have an inumber of
FUSE_ROOT_ID, which is 1.  However, the ext2 filesystem defines the root
inode number to be EXT2_ROOT_INO, which is 2.  This dissonance means
that we have to have translator functions, and that any access to
inumber 1 (the ext2 badblocks file) will instead redirect to the root
directory.

That's horrible.  Use the new mount option to set the root directory
nodeid to EXT2_ROOT_INO so that we don't need this translation.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index abbc67bccef786..3be19f59fc3976 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -266,6 +266,7 @@ struct fuse4fs {
 	int dirsync;
 	int unmount_in_destroy;
 	int noblkdev;
+	int translate_inums;
 
 	enum fuse4fs_opstate opstate;
 	int logfd;
@@ -335,17 +336,19 @@ struct fuse4fs {
 #define FUSE4FS_CHECK_CONTEXT_ABORT(ff) \
 	__FUSE4FS_CHECK_CONTEXT((ff), abort(), abort())
 
-static inline void fuse4fs_ino_from_fuse(ext2_ino_t *inop, fuse_ino_t fino)
+static inline void fuse4fs_ino_from_fuse(const struct fuse4fs *ff,
+					 ext2_ino_t *inop, fuse_ino_t fino)
 {
-	if (fino == FUSE_ROOT_ID)
+	if (ff->translate_inums && fino == FUSE_ROOT_ID)
 		*inop = EXT2_ROOT_INO;
 	else
 		*inop = fino;
 }
 
-static inline void fuse4fs_ino_to_fuse(fuse_ino_t *finop, ext2_ino_t ino)
+static inline void fuse4fs_ino_to_fuse(const struct fuse4fs *ff,
+				       fuse_ino_t *finop, ext2_ino_t ino)
 {
-	if (ino == EXT2_ROOT_INO)
+	if (ff->translate_inums && ino == EXT2_ROOT_INO)
 		*finop = FUSE_ROOT_ID;
 	else
 		*finop = ino;
@@ -361,7 +364,7 @@ static inline void fuse4fs_ino_to_fuse(fuse_ino_t *finop, ext2_ino_t ino)
 			fuse_reply_err((req), EIO); \
 			return; \
 		} \
-		fuse4fs_ino_from_fuse(ext2_inop, fuse_ino); \
+		fuse4fs_ino_from_fuse(fuse4fs_get(req), ext2_inop, fuse_ino); \
 	} while (0)
 
 static int __translate_error(ext2_filsys fs, ext2_ino_t ino, errcode_t err,
@@ -1765,7 +1768,7 @@ static int fuse4fs_stat_inode(struct fuse4fs *ff, ext2_ino_t ino,
 			statbuf->st_rdev = inodep->i_block[1];
 	}
 
-	fuse4fs_ino_to_fuse(&entry->ino, ino);
+	fuse4fs_ino_to_fuse(ff, &entry->ino, ino);
 	entry->generation = inodep->i_generation;
 	entry->attr_timeout = FUSE4FS_ATTR_TIMEOUT;
 	entry->entry_timeout = FUSE4FS_ATTR_TIMEOUT;
@@ -7410,6 +7413,7 @@ int main(int argc, char *argv[])
 		.iomap_state = IOMAP_UNKNOWN,
 		.iomap_dev = FUSE_IOMAP_DEV_NULL,
 #endif
+		.translate_inums = 1,
 	};
 	errcode_t err;
 	FILE *orig_stderr = stderr;
@@ -7511,6 +7515,19 @@ int main(int argc, char *argv[])
 		fctx.unmount_in_destroy = 1;
 	}
 
+	if (iomap_detected) {
+		/*
+		 * The root_nodeid mount option was added when iomap support
+		 * was added to fuse.  This enables us to control the root
+		 * nodeid in the kernel, which enables a 1:1 translation of
+		 * ext2 to kernel inumbers.
+		 */
+		snprintf(extra_args, BUFSIZ, "-oroot_nodeid=%d",
+			 EXT2_ROOT_INO);
+		fuse_opt_add_arg(&args, extra_args);
+		fctx.translate_inums = 0;
+	}
+
 	if (!fctx.cache_size)
 		fctx.cache_size = default_cache_size();
 	if (fctx.cache_size) {

[PATCH 01/10] fuse2fs: add strictatime/lazytime mount options

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

In iomap mode, we can support the strictatime/lazytime mount options.
Add them to fuse2fs.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.1.in |    6 ++++++
 fuse4fs/fuse4fs.c    |   28 ++++++++++++++++++++++++++++
 misc/fuse2fs.1.in    |    6 ++++++
 misc/fuse2fs.c       |   28 ++++++++++++++++++++++++++++
 4 files changed, 68 insertions(+)


diff --git a/fuse4fs/fuse4fs.1.in b/fuse4fs/fuse4fs.1.in
index 8855867d27101d..119cbcc903d8af 100644
--- a/fuse4fs/fuse4fs.1.in
+++ b/fuse4fs/fuse4fs.1.in
@@ -90,6 +90,9 @@ .SS "fuse4fs options:"
 .I nosuid
 ) later.
 .TP
+\fB-o\fR lazytime
+if iomap is enabled, enable lazy updates of timestamps
+.TP
 \fB-o\fR lockfile=path
 use this file to control access to the filesystem
 .TP
@@ -98,6 +101,9 @@ .SS "fuse4fs options:"
 .TP
 \fB-o\fR norecovery
 do not replay the journal and mount the file system read-only
+.TP
+\fB-o\fR strictatime
+if iomap is enabled, update atime on every access
 .SS "FUSE options:"
 .TP
 \fB-d -o\fR debug
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 3be19f59fc3976..bc2cf41085695f 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -267,6 +267,7 @@ struct fuse4fs {
 	int unmount_in_destroy;
 	int noblkdev;
 	int translate_inums;
+	int iomap_passthrough_options;
 
 	enum fuse4fs_opstate opstate;
 	int logfd;
@@ -1648,6 +1649,8 @@ static void fuse4fs_iomap_enable(struct fuse_conn_info *conn,
 	if (!fuse4fs_iomap_enabled(ff)) {
 		if (ff->iomap_want == FT_ENABLE)
 			err_printf(ff, "%s\n", _("Could not enable iomap."));
+		if (ff->iomap_passthrough_options)
+			err_printf(ff, "%s\n", _("Some mount options require iomap."));
 		return;
 	}
 }
@@ -7070,6 +7073,7 @@ enum {
 	FUSE4FS_ERRORS_BEHAVIOR,
 #ifdef HAVE_FUSE_IOMAP
 	FUSE4FS_IOMAP,
+	FUSE4FS_IOMAP_PASSTHROUGH,
 #endif
 };
 
@@ -7096,6 +7100,17 @@ static struct fuse_opt fuse4fs_opts[] = {
 #endif
 	FUSE4FS_OPT("noblkdev",		noblkdev,		1),
 
+#ifdef HAVE_FUSE_IOMAP
+#ifdef MS_LAZYTIME
+	FUSE_OPT_KEY("lazytime",	FUSE4FS_IOMAP_PASSTHROUGH),
+	FUSE_OPT_KEY("nolazytime",	FUSE4FS_IOMAP_PASSTHROUGH),
+#endif
+#ifdef MS_STRICTATIME
+	FUSE_OPT_KEY("strictatime",	FUSE4FS_IOMAP_PASSTHROUGH),
+	FUSE_OPT_KEY("nostrictatime",	FUSE4FS_IOMAP_PASSTHROUGH),
+#endif
+#endif
+
 	FUSE_OPT_KEY("user_xattr",	FUSE4FS_IGNORED),
 	FUSE_OPT_KEY("noblock_validity", FUSE4FS_IGNORED),
 	FUSE_OPT_KEY("nodelalloc",	FUSE4FS_IGNORED),
@@ -7122,6 +7137,12 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
 	struct fuse4fs *ff = data;
 
 	switch (key) {
+#ifdef HAVE_FUSE_IOMAP
+	case FUSE4FS_IOMAP_PASSTHROUGH:
+		ff->iomap_passthrough_options = 1;
+		/* pass through to libfuse */
+		return 1;
+#endif
 	case FUSE4FS_DIRSYNC:
 		ff->dirsync = 1;
 		/* pass through to libfuse */
@@ -7515,6 +7536,13 @@ int main(int argc, char *argv[])
 		fctx.unmount_in_destroy = 1;
 	}
 
+	if (fctx.iomap_passthrough_options && !iomap_detected) {
+		err_printf(&fctx, "%s\n",
+			   _("Some mount options require iomap."));
+		ret |= 1;
+		goto out;
+	}
+
 	if (iomap_detected) {
 		/*
 		 * The root_nodeid mount option was added when iomap support
diff --git a/misc/fuse2fs.1.in b/misc/fuse2fs.1.in
index 2b55fa0e723966..0c0934f03c9543 100644
--- a/misc/fuse2fs.1.in
+++ b/misc/fuse2fs.1.in
@@ -90,6 +90,9 @@ .SS "fuse2fs options:"
 .I nosuid
 ) later.
 .TP
+\fB-o\fR lazytime
+if iomap is enabled, enable lazy updates of timestamps
+.TP
 \fB-o\fR lockfile=path
 use this file to control access to the filesystem
 .TP
@@ -98,6 +101,9 @@ .SS "fuse2fs options:"
 .TP
 \fB-o\fR norecovery
 do not replay the journal and mount the file system read-only
+.TP
+\fB-o\fR strictatime
+if iomap is enabled, update atime on every access
 .SS "FUSE options:"
 .TP
 \fB-d -o\fR debug
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 0832a758bdad79..8f7194f4f815ee 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -260,6 +260,7 @@ struct fuse2fs {
 	int dirsync;
 	int unmount_in_destroy;
 	int noblkdev;
+	int iomap_passthrough_options;
 
 	enum fuse2fs_opstate opstate;
 	int logfd;
@@ -1453,6 +1454,8 @@ static void fuse2fs_iomap_enable(struct fuse_conn_info *conn,
 	if (!fuse2fs_iomap_enabled(ff)) {
 		if (ff->iomap_want == FT_ENABLE)
 			err_printf(ff, "%s\n", _("Could not enable iomap."));
+		if (ff->iomap_passthrough_options)
+			err_printf(ff, "%s\n", _("Some mount options require iomap."));
 		return;
 	}
 }
@@ -6590,6 +6593,7 @@ enum {
 	FUSE2FS_ERRORS_BEHAVIOR,
 #ifdef HAVE_FUSE_IOMAP
 	FUSE2FS_IOMAP,
+	FUSE2FS_IOMAP_PASSTHROUGH,
 #endif
 };
 
@@ -6616,6 +6620,17 @@ static struct fuse_opt fuse2fs_opts[] = {
 #endif
 	FUSE2FS_OPT("noblkdev",		noblkdev,		1),
 
+#ifdef HAVE_FUSE_IOMAP
+#ifdef MS_LAZYTIME
+	FUSE_OPT_KEY("lazytime",	FUSE2FS_IOMAP_PASSTHROUGH),
+	FUSE_OPT_KEY("nolazytime",	FUSE2FS_IOMAP_PASSTHROUGH),
+#endif
+#ifdef MS_STRICTATIME
+	FUSE_OPT_KEY("strictatime",	FUSE2FS_IOMAP_PASSTHROUGH),
+	FUSE_OPT_KEY("nostrictatime",	FUSE2FS_IOMAP_PASSTHROUGH),
+#endif
+#endif
+
 	FUSE_OPT_KEY("user_xattr",	FUSE2FS_IGNORED),
 	FUSE_OPT_KEY("noblock_validity", FUSE2FS_IGNORED),
 	FUSE_OPT_KEY("nodelalloc",	FUSE2FS_IGNORED),
@@ -6642,6 +6657,12 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
 	struct fuse2fs *ff = data;
 
 	switch (key) {
+#ifdef HAVE_FUSE_IOMAP
+	case FUSE2FS_IOMAP_PASSTHROUGH:
+		ff->iomap_passthrough_options = 1;
+		/* pass through to libfuse */
+		return 1;
+#endif
 	case FUSE2FS_DIRSYNC:
 		ff->dirsync = 1;
 		/* pass through to libfuse */
@@ -6934,6 +6955,13 @@ int main(int argc, char *argv[])
 		fctx.unmount_in_destroy = 1;
 	}
 
+	if (fctx.iomap_passthrough_options && !iomap_detected) {
+		err_printf(&fctx, "%s\n",
+			   _("Some mount options require iomap."));
+		ret |= 1;
+		goto out;
+	}
+
 	if (!fctx.cache_size)
 		fctx.cache_size = default_cache_size();
 	if (fctx.cache_size) {

[PATCH 02/10] fuse2fs: skip permission checking on utimens when iomap is enabled

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

When iomap is enabled, the kernel is in charge of enforcing permissions
checks on timestamp updates for files.  We needn't do that in userspace
anymore.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   11 +++++++----
 misc/fuse2fs.c    |   11 +++++++----
 2 files changed, 14 insertions(+), 8 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index bc2cf41085695f..06be49164c783d 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -4850,13 +4850,16 @@ static int fuse4fs_utimens(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 
 	/*
 	 * ext4 allows timestamp updates of append-only files but only if we're
-	 * setting to current time
+	 * setting to current time.  If iomap is enabled, the kernel does the
+	 * permission checking for timestamp updates; skip the access check.
 	 */
 	if (aact == TA_NOW && mact == TA_NOW)
 		access |= A_OK;
-	ret = fuse4fs_inum_access(ff, ctxt, ino, access);
-	if (ret)
-		return ret;
+	if (!fuse4fs_iomap_enabled(ff)) {
+		ret = fuse4fs_inum_access(ff, ctxt, ino, access);
+		if (ret)
+			return ret;
+	}
 
 	if (aact != TA_OMIT)
 		EXT4_INODE_SET_XTIME(i_atime, &atime, inode);
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 8f7194f4f815ee..716793b5fa485c 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -4500,13 +4500,16 @@ static int op_utimens(const char *path, const struct timespec ctv[2],
 
 	/*
 	 * ext4 allows timestamp updates of append-only files but only if we're
-	 * setting to current time
+	 * setting to current time.  If iomap is enabled, the kernel does the
+	 * permission checking for timestamp updates; skip the access check.
 	 */
 	if (ctv[0].tv_nsec == UTIME_NOW && ctv[1].tv_nsec == UTIME_NOW)
 		access |= A_OK;
-	ret = check_inum_access(ff, ino, access);
-	if (ret)
-		goto out;
+	if (!fuse2fs_iomap_enabled(ff)) {
+		ret = check_inum_access(ff, ino, access);
+		if (ret)
+			goto out;
+	}
 
 	err = fuse2fs_read_inode(fs, ino, &inode);
 	if (err) {

[PATCH 03/10] fuse2fs: let the kernel tell us about acl/mode updates

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

When the kernel is running in iomap mode, it will also manage all the
ACL updates and the resulting file mode changes for us.  Disable the
manual implementation of it in fuse2fs.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |    4 ++--
 misc/fuse2fs.c    |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 06be49164c783d..184066855517b1 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -2137,7 +2137,7 @@ static int fuse4fs_propagate_default_acls(struct fuse4fs *ff, ext2_ino_t parent,
 	size_t deflen;
 	int ret;
 
-	if (!ff->acl || S_ISDIR(mode))
+	if (!ff->acl || S_ISDIR(mode) || fuse4fs_iomap_enabled(ff))
 		return 0;
 
 	ret = fuse4fs_getxattr(ff, parent, XATTR_NAME_POSIX_ACL_DEFAULT, &def,
@@ -3512,7 +3512,7 @@ static int fuse4fs_chmod(struct fuse4fs *ff, fuse_req_t req, ext2_ino_t ino,
 	 * of the user's groups, but FUSE only tells us about the primary
 	 * group.
 	 */
-	if (!fuse4fs_is_superuser(ff, ctxt)) {
+	if (!fuse4fs_iomap_enabled(ff) && !fuse4fs_is_superuser(ff, ctxt)) {
 		ret = fuse4fs_in_file_group(ff, req, inode);
 		if (ret < 0)
 			return ret;
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 716793b5fa485c..2b3c09a59270bc 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1937,7 +1937,7 @@ static int propagate_default_acls(struct fuse2fs *ff, ext2_ino_t parent,
 	size_t deflen;
 	int ret;
 
-	if (!ff->acl || S_ISDIR(mode))
+	if (!ff->acl || S_ISDIR(mode) || fuse2fs_iomap_enabled(ff))
 		return 0;
 
 	ret = __getxattr(ff, parent, XATTR_NAME_POSIX_ACL_DEFAULT, &def,
@@ -3213,7 +3213,7 @@ static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
 	 * of the user's groups, but FUSE only tells us about the primary
 	 * group.
 	 */
-	if (!is_superuser(ff, ctxt)) {
+	if (!fuse2fs_iomap_enabled(ff) && !is_superuser(ff, ctxt)) {
 		ret = in_file_group(ctxt, &inode);
 		if (ret < 0)
 			goto out;

[PATCH 04/10] fuse2fs: better debugging for file mode updates

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Improve the tracing of a chmod operation so that we can debug file mode
updates.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   10 ++++++----
 misc/fuse2fs.c    |   12 +++++++-----
 2 files changed, 13 insertions(+), 9 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 184066855517b1..ab807f1479870c 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -3495,6 +3495,7 @@ static int fuse4fs_chmod(struct fuse4fs *ff, fuse_req_t req, ext2_ino_t ino,
 			 mode_t mode, struct ext2_inode_large *inode)
 {
 	const struct fuse_ctx *ctxt = fuse_req_ctx(req);
+	mode_t new_mode;
 	int ret = 0;
 
 	dbg_printf(ff, "%s: ino=%d mode=0%o\n", __func__, ino, mode);
@@ -3521,11 +3522,12 @@ static int fuse4fs_chmod(struct fuse4fs *ff, fuse_req_t req, ext2_ino_t ino,
 			mode &= ~S_ISGID;
 	}
 
-	inode->i_mode &= ~0xFFF;
-	inode->i_mode |= mode & 0xFFF;
+	new_mode = (inode->i_mode & ~0xFFF) | (mode & 0xFFF);
 
-	dbg_printf(ff, "%s: ino=%d new_mode=0%o\n",
-		   __func__, ino, inode->i_mode);
+	dbg_printf(ff, "%s: ino=%d old_mode=0%o new_mode=0%o\n",
+		   __func__, ino, inode->i_mode, new_mode);
+
+	inode->i_mode = new_mode;
 
 	return 0;
 }
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 2b3c09a59270bc..53adf8542e2f42 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -3184,6 +3184,7 @@ static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
 	errcode_t err;
 	ext2_ino_t ino;
 	struct ext2_inode_large inode;
+	mode_t new_mode;
 	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
@@ -3222,11 +3223,12 @@ static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
 			mode &= ~S_ISGID;
 	}
 
-	inode.i_mode &= ~0xFFF;
-	inode.i_mode |= mode & 0xFFF;
+	new_mode = (inode.i_mode & ~0xFFF) | (mode & 0xFFF);
 
-	dbg_printf(ff, "%s: path=%s new_mode=0%o ino=%d\n", __func__,
-		   path, inode.i_mode, ino);
+	dbg_printf(ff, "%s: path=%s old_mode=0%o new_mode=0%o ino=%d\n",
+		   __func__, path, inode.i_mode, new_mode, ino);
+
+	inode.i_mode = new_mode;
 
 	ret = update_ctime(fs, ino, &inode);
 	if (ret)
@@ -3246,12 +3248,12 @@ static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
 static int op_chown(const char *path, uid_t owner, gid_t group,
 		    struct fuse_file_info *fi)
 {
+	struct ext2_inode_large inode;
 	struct fuse_context *ctxt = fuse_get_context();
 	struct fuse2fs *ff = fuse2fs_get();
 	ext2_filsys fs;
 	errcode_t err;
 	ext2_ino_t ino;
-	struct ext2_inode_large inode;
 	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);

[PATCH 05/10] fuse2fs: debug timestamp updates

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracing for timestamp updates to files.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 misc/fuse2fs.c |   97 +++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 61 insertions(+), 36 deletions(-)


diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 53adf8542e2f42..aedd1add48db82 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -686,7 +686,8 @@ static void increment_version(struct ext2_inode_large *inode)
 		inode->i_version_hi = ver >> 32;
 }
 
-static void init_times(struct ext2_inode_large *inode)
+static void fuse2fs_init_timestamps(struct fuse2fs *ff, ext2_ino_t ino,
+				    struct ext2_inode_large *inode)
 {
 	struct timespec now;
 
@@ -696,11 +697,15 @@ static void init_times(struct ext2_inode_large *inode)
 	EXT4_INODE_SET_XTIME(i_mtime, &now, inode);
 	EXT4_EINODE_SET_XTIME(i_crtime, &now, inode);
 	increment_version(inode);
+
+	dbg_printf(ff, "%s: ino=%u time %ld:%lu\n", __func__, ino, now.tv_sec,
+		   now.tv_nsec);
 }
 
-static int update_ctime(ext2_filsys fs, ext2_ino_t ino,
-			struct ext2_inode_large *pinode)
+static int fuse2fs_update_ctime(struct fuse2fs *ff, ext2_ino_t ino,
+				struct ext2_inode_large *pinode)
 {
+	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct timespec now;
 	struct ext2_inode_large inode;
@@ -711,6 +716,10 @@ static int update_ctime(ext2_filsys fs, ext2_ino_t ino,
 	if (pinode) {
 		increment_version(pinode);
 		EXT4_INODE_SET_XTIME(i_ctime, &now, pinode);
+
+		dbg_printf(ff, "%s: ino=%u ctime %ld:%lu\n", __func__, ino,
+			   now.tv_sec, now.tv_nsec);
+
 		return 0;
 	}
 
@@ -722,6 +731,9 @@ static int update_ctime(ext2_filsys fs, ext2_ino_t ino,
 	increment_version(&inode);
 	EXT4_INODE_SET_XTIME(i_ctime, &now, &inode);
 
+	dbg_printf(ff, "%s: ino=%u ctime %ld:%lu\n", __func__, ino,
+		   now.tv_sec, now.tv_nsec);
+
 	err = fuse2fs_write_inode(fs, ino, &inode);
 	if (err)
 		return translate_error(fs, ino, err);
@@ -729,8 +741,9 @@ static int update_ctime(ext2_filsys fs, ext2_ino_t ino,
 	return 0;
 }
 
-static int update_atime(ext2_filsys fs, ext2_ino_t ino)
+static int fuse2fs_update_atime(struct fuse2fs *ff, ext2_ino_t ino)
 {
+	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct ext2_inode_large inode, *pinode;
 	struct timespec atime, mtime, now;
@@ -749,6 +762,10 @@ static int update_atime(ext2_filsys fs, ext2_ino_t ino)
 	dmtime = mtime.tv_sec + ((double)mtime.tv_nsec / NSEC_PER_SEC);
 	dnow = now.tv_sec + ((double)now.tv_nsec / NSEC_PER_SEC);
 
+	dbg_printf(ff, "%s: ino=%u atime %ld:%lu mtime %ld:%lu now %ld:%lu\n",
+		   __func__, ino, atime.tv_sec, atime.tv_nsec, mtime.tv_sec,
+		   mtime.tv_nsec, now.tv_sec, now.tv_nsec);
+
 	/*
 	 * If atime is newer than mtime and atime hasn't been updated in thirty
 	 * seconds, skip the atime update.  Same idea as Linux "relatime".  Use
@@ -765,9 +782,10 @@ static int update_atime(ext2_filsys fs, ext2_ino_t ino)
 	return 0;
 }
 
-static int update_mtime(ext2_filsys fs, ext2_ino_t ino,
-			struct ext2_inode_large *pinode)
+static int fuse2fs_update_mtime(struct fuse2fs *ff, ext2_ino_t ino,
+				struct ext2_inode_large *pinode)
 {
+	ext2_filsys fs = ff->fs;
 	errcode_t err;
 	struct ext2_inode_large inode;
 	struct timespec now;
@@ -777,6 +795,10 @@ static int update_mtime(ext2_filsys fs, ext2_ino_t ino,
 		EXT4_INODE_SET_XTIME(i_mtime, &now, pinode);
 		EXT4_INODE_SET_XTIME(i_ctime, &now, pinode);
 		increment_version(pinode);
+
+		dbg_printf(ff, "%s: ino=%u mtime/ctime %ld:%lu\n",
+			   __func__, ino, now.tv_sec, now.tv_nsec);
+
 		return 0;
 	}
 
@@ -789,6 +811,9 @@ static int update_mtime(ext2_filsys fs, ext2_ino_t ino,
 	EXT4_INODE_SET_XTIME(i_ctime, &now, &inode);
 	increment_version(&inode);
 
+	dbg_printf(ff, "%s: ino=%u mtime/ctime %ld:%lu\n",
+		   __func__, ino, now.tv_sec, now.tv_nsec);
+
 	err = fuse2fs_write_inode(fs, ino, &inode);
 	if (err)
 		return translate_error(fs, ino, err);
@@ -1858,7 +1883,7 @@ static int op_readlink(const char *path, char *buf, size_t len)
 	buf[len] = 0;
 
 	if (fuse2fs_is_writeable(ff)) {
-		ret = update_atime(fs, ino);
+		ret = fuse2fs_update_atime(ff, ino);
 		if (ret)
 			goto out;
 	}
@@ -2132,7 +2157,7 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
 		goto out2;
 	}
 
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse2fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -2155,7 +2180,7 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
 	}
 
 	inode.i_generation = ff->next_generation++;
-	init_times(&inode);
+	fuse2fs_init_timestamps(ff, child, &inode);
 	err = fuse2fs_write_inode(fs, child, &inode);
 	if (err) {
 		ret = translate_error(fs, child, err);
@@ -2241,7 +2266,7 @@ static int op_mkdir(const char *path, mode_t mode)
 		goto out2;
 	}
 
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse2fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -2268,7 +2293,7 @@ static int op_mkdir(const char *path, mode_t mode)
 	if (parent_sgid)
 		inode.i_mode |= S_ISGID;
 	inode.i_generation = ff->next_generation++;
-	init_times(&inode);
+	fuse2fs_init_timestamps(ff, child, &inode);
 
 	err = fuse2fs_write_inode(fs, child, &inode);
 	if (err) {
@@ -2351,7 +2376,7 @@ static int fuse2fs_unlink(struct fuse2fs *ff, const char *path,
 	if (err)
 		return translate_error(fs, dir, err);
 
-	ret = update_mtime(fs, dir, NULL);
+	ret = fuse2fs_update_mtime(ff, dir, NULL);
 	if (ret)
 		return ret;
 
@@ -2430,7 +2455,7 @@ static int remove_inode(struct fuse2fs *ff, ext2_ino_t ino)
 		inode.i_links_count--;
 	}
 
-	ret = update_ctime(fs, ino, &inode);
+	ret = fuse2fs_update_ctime(ff, ino, &inode);
 	if (ret)
 		return ret;
 
@@ -2604,7 +2629,7 @@ static int __op_rmdir(struct fuse2fs *ff, const char *path)
 		}
 		if (inode.i_links_count > 1)
 			inode.i_links_count--;
-		ret = update_mtime(fs, rds.parent, &inode);
+		ret = fuse2fs_update_mtime(ff, rds.parent, &inode);
 		if (ret)
 			goto out;
 		err = fuse2fs_write_inode(fs, rds.parent, &inode);
@@ -2701,7 +2726,7 @@ static int op_symlink(const char *src, const char *dest)
 	}
 
 	/* Update parent dir's mtime */
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse2fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -2725,7 +2750,7 @@ static int op_symlink(const char *src, const char *dest)
 	fuse2fs_set_uid(&inode, ctxt->uid);
 	fuse2fs_set_gid(&inode, gid);
 	inode.i_generation = ff->next_generation++;
-	init_times(&inode);
+	fuse2fs_init_timestamps(ff, child, &inode);
 
 	err = fuse2fs_write_inode(fs, child, &inode);
 	if (err) {
@@ -2970,11 +2995,11 @@ static int op_rename(const char *from, const char *to,
 	}
 
 	/* Update timestamps */
-	ret = update_ctime(fs, from_ino, NULL);
+	ret = fuse2fs_update_ctime(ff, from_ino, NULL);
 	if (ret)
 		goto out2;
 
-	ret = update_mtime(fs, to_dir_ino, NULL);
+	ret = fuse2fs_update_mtime(ff, to_dir_ino, NULL);
 	if (ret)
 		goto out2;
 
@@ -3063,7 +3088,7 @@ static int op_link(const char *src, const char *dest)
 		goto out2;
 
 	inode.i_links_count++;
-	ret = update_ctime(fs, ino, &inode);
+	ret = fuse2fs_update_ctime(ff, ino, &inode);
 	if (ret)
 		goto out2;
 
@@ -3082,7 +3107,7 @@ static int op_link(const char *src, const char *dest)
 		goto out2;
 	}
 
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse2fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -3230,7 +3255,7 @@ static int op_chmod(const char *path, mode_t mode, struct fuse_file_info *fi)
 
 	inode.i_mode = new_mode;
 
-	ret = update_ctime(fs, ino, &inode);
+	ret = fuse2fs_update_ctime(ff, ino, &inode);
 	if (ret)
 		goto out;
 
@@ -3297,7 +3322,7 @@ static int op_chown(const char *path, uid_t owner, gid_t group,
 		fuse2fs_set_gid(&inode, group);
 	}
 
-	ret = update_ctime(fs, ino, &inode);
+	ret = fuse2fs_update_ctime(ff, ino, &inode);
 	if (ret)
 		goto out;
 
@@ -3427,7 +3452,7 @@ static int fuse2fs_truncate(struct fuse2fs *ff, ext2_ino_t ino, off_t new_size)
 	if (err)
 		return translate_error(fs, ino, err);
 
-	ret = update_mtime(fs, ino, NULL);
+	ret = fuse2fs_update_mtime(ff, ino, NULL);
 	if (ret)
 		return ret;
 
@@ -3655,7 +3680,7 @@ static int op_read(const char *path EXT2FS_ATTR((unused)), char *buf,
 	}
 
 	if (fh->check_flags != X_OK && fuse2fs_is_writeable(ff)) {
-		ret = update_atime(fs, fh->ino);
+		ret = fuse2fs_update_atime(ff, fh->ino);
 		if (ret)
 			goto out;
 	}
@@ -3739,7 +3764,7 @@ static int op_write(const char *path EXT2FS_ATTR((unused)),
 		goto out;
 	}
 
-	ret = update_mtime(fs, fh->ino, NULL);
+	ret = fuse2fs_update_mtime(ff, fh->ino, NULL);
 	if (ret)
 		goto out;
 
@@ -4101,7 +4126,7 @@ static int op_setxattr(const char *path EXT2FS_ATTR((unused)),
 		goto out2;
 	}
 
-	ret = update_ctime(fs, ino, NULL);
+	ret = fuse2fs_update_ctime(ff, ino, NULL);
 out2:
 	err = ext2fs_xattrs_close(&h);
 	if (!ret && err)
@@ -4195,7 +4220,7 @@ static int op_removexattr(const char *path, const char *key)
 		goto out2;
 	}
 
-	ret = update_ctime(fs, ino, NULL);
+	ret = fuse2fs_update_ctime(ff, ino, NULL);
 out2:
 	err = ext2fs_xattrs_close(&h);
 	if (err && !ret)
@@ -4313,7 +4338,7 @@ static int op_readdir(const char *path EXT2FS_ATTR((unused)), void *buf,
 	}
 
 	if (fuse2fs_is_writeable(ff)) {
-		ret = update_atime(i.fs, fh->ino);
+		ret = fuse2fs_update_atime(ff, fh->ino);
 		if (ret)
 			goto out;
 	}
@@ -4418,7 +4443,7 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 		goto out2;
 	}
 
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse2fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -4449,7 +4474,7 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
 	}
 
 	inode.i_generation = ff->next_generation++;
-	init_times(&inode);
+	fuse2fs_init_timestamps(ff, child, &inode);
 	err = fuse2fs_write_inode(fs, child, &inode);
 	if (err) {
 		ret = translate_error(fs, child, err);
@@ -4533,7 +4558,7 @@ static int op_utimens(const char *path, const struct timespec ctv[2],
 	if (tv[1].tv_nsec != UTIME_OMIT)
 		EXT4_INODE_SET_XTIME(i_mtime, &tv[1], &inode);
 #endif /* UTIME_OMIT */
-	ret = update_ctime(fs, ino, &inode);
+	ret = fuse2fs_update_ctime(ff, ino, &inode);
 	if (ret)
 		goto out;
 
@@ -4601,7 +4626,7 @@ static int ioctl_setflags(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
 	if (ret)
 		return ret;
 
-	ret = update_ctime(fs, fh->ino, &inode);
+	ret = fuse2fs_update_ctime(ff, fh->ino, &inode);
 	if (ret)
 		return ret;
 
@@ -4648,7 +4673,7 @@ static int ioctl_setversion(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
 
 	inode.i_generation = generation;
 
-	ret = update_ctime(fs, fh->ino, &inode);
+	ret = fuse2fs_update_ctime(ff, fh->ino, &inode);
 	if (ret)
 		return ret;
 
@@ -4779,7 +4804,7 @@ static int ioctl_fssetxattr(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
 	if (ext2fs_inode_includes(inode_size, i_projid))
 		inode.i_projid = fsx->fsx_projid;
 
-	ret = update_ctime(fs, fh->ino, &inode);
+	ret = fuse2fs_update_ctime(ff, fh->ino, &inode);
 	if (ret)
 		return ret;
 
@@ -5048,7 +5073,7 @@ static int fuse2fs_allocate_range(struct fuse2fs *ff,
 		}
 	}
 
-	err = update_mtime(fs, fh->ino, &inode);
+	err = fuse2fs_update_mtime(ff, fh->ino, &inode);
 	if (err)
 		return err;
 
@@ -5221,7 +5246,7 @@ static int fuse2fs_punch_range(struct fuse2fs *ff,
 			return translate_error(fs, fh->ino, err);
 	}
 
-	err = update_mtime(fs, fh->ino, &inode);
+	err = fuse2fs_update_mtime(ff, fh->ino, &inode);
 	if (err)
 		return err;
 

[PATCH 06/10] fuse2fs: use coarse timestamps for iomap mode

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

In iomap mode, the kernel is responsible for maintaining timestamps
because file writes don't upcall to fuse2fs.  The kernel's predicate for
deciding if [cm]time should be updated bases its decisions off [cm]time
being an exact match for the coarse clock (instead of checking that
[cm]time < coarse_clock) which means that fuse2fs setting a fine-grained
timestamp that is slightly ahead of the coarse clock can result in
timestamps appearing to go backwards.  generic/423 doesn't like seeing
btime > ctime from statx, so we'll use the coarse clock in iomap mode.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |  110 +++++++++++++++++++++++++++++++----------------------
 misc/fuse2fs.c    |   34 ++++++++++++----
 2 files changed, 90 insertions(+), 54 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index ab807f1479870c..5673a545b06b31 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -827,8 +827,24 @@ static inline void fuse4fs_dump_extents(struct fuse4fs *ff, ext2_ino_t ino,
 	ext2fs_extent_free(extents);
 }
 
-static void get_now(struct timespec *now)
+static void fuse4fs_get_now(struct fuse4fs *ff, struct timespec *now)
 {
+#ifdef CLOCK_REALTIME_COARSE
+	/*
+	 * In iomap mode, the kernel is responsible for maintaining timestamps
+	 * because file writes don't upcall to fuse4fs.  The kernel's predicate
+	 * for deciding if [cm]time should be updated bases its decisions off
+	 * [cm]time being an exact match for the coarse clock (instead of
+	 * checking that [cm]time < coarse_clock) which means that fuse4fs
+	 * setting a fine-grained timestamp that is slightly ahead of the
+	 * coarse clock can result in timestamps appearing to go backwards.
+	 * generic/423 doesn't like seeing btime > ctime from statx, so we'll
+	 * use the coarse clock in iomap mode.
+	 */
+	if (fuse4fs_iomap_enabled(ff) &&
+	    !clock_gettime(CLOCK_REALTIME_COARSE, now))
+		return;
+#endif
 #ifdef CLOCK_REALTIME
 	if (!clock_gettime(CLOCK_REALTIME, now))
 		return;
@@ -851,11 +867,12 @@ static void increment_version(struct ext2_inode_large *inode)
 		inode->i_version_hi = ver >> 32;
 }
 
-static void init_times(struct ext2_inode_large *inode)
+static void fuse4fs_init_timestamps(struct fuse4fs *ff,
+				    struct ext2_inode_large *inode)
 {
 	struct timespec now;
 
-	get_now(&now);
+	fuse4fs_get_now(ff, &now);
 	EXT4_INODE_SET_XTIME(i_atime, &now, inode);
 	EXT4_INODE_SET_XTIME(i_ctime, &now, inode);
 	EXT4_INODE_SET_XTIME(i_mtime, &now, inode);
@@ -863,14 +880,15 @@ static void init_times(struct ext2_inode_large *inode)
 	increment_version(inode);
 }
 
-static int update_ctime(ext2_filsys fs, ext2_ino_t ino,
-			struct ext2_inode_large *pinode)
+static int fuse4fs_update_ctime(struct fuse4fs *ff, ext2_ino_t ino,
+				struct ext2_inode_large *pinode)
 {
-	errcode_t err;
 	struct timespec now;
 	struct ext2_inode_large inode;
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
 
-	get_now(&now);
+	fuse4fs_get_now(ff, &now);
 
 	/* If user already has a inode buffer, just update that */
 	if (pinode) {
@@ -894,12 +912,13 @@ static int update_ctime(ext2_filsys fs, ext2_ino_t ino,
 	return 0;
 }
 
-static int update_atime(ext2_filsys fs, ext2_ino_t ino)
+static int fuse4fs_update_atime(struct fuse4fs *ff, ext2_ino_t ino)
 {
-	errcode_t err;
 	struct ext2_inode_large inode, *pinode;
 	struct timespec atime, mtime, now;
+	ext2_filsys fs = ff->fs;
 	double datime, dmtime, dnow;
+	errcode_t err;
 
 	err = fuse4fs_read_inode(fs, ino, &inode);
 	if (err)
@@ -908,7 +927,7 @@ static int update_atime(ext2_filsys fs, ext2_ino_t ino)
 	pinode = &inode;
 	EXT4_INODE_GET_XTIME(i_atime, &atime, pinode);
 	EXT4_INODE_GET_XTIME(i_mtime, &mtime, pinode);
-	get_now(&now);
+	fuse4fs_get_now(ff, &now);
 
 	datime = atime.tv_sec + ((double)atime.tv_nsec / NSEC_PER_SEC);
 	dmtime = mtime.tv_sec + ((double)mtime.tv_nsec / NSEC_PER_SEC);
@@ -930,15 +949,16 @@ static int update_atime(ext2_filsys fs, ext2_ino_t ino)
 	return 0;
 }
 
-static int update_mtime(ext2_filsys fs, ext2_ino_t ino,
-			struct ext2_inode_large *pinode)
+static int fuse4fs_update_mtime(struct fuse4fs *ff, ext2_ino_t ino,
+				struct ext2_inode_large *pinode)
 {
-	errcode_t err;
 	struct ext2_inode_large inode;
 	struct timespec now;
+	ext2_filsys fs = ff->fs;
+	errcode_t err;
 
 	if (pinode) {
-		get_now(&now);
+		fuse4fs_get_now(ff, &now);
 		EXT4_INODE_SET_XTIME(i_mtime, &now, pinode);
 		EXT4_INODE_SET_XTIME(i_ctime, &now, pinode);
 		increment_version(pinode);
@@ -949,7 +969,7 @@ static int update_mtime(ext2_filsys fs, ext2_ino_t ino,
 	if (err)
 		return translate_error(fs, ino, err);
 
-	get_now(&now);
+	fuse4fs_get_now(ff, &now);
 	EXT4_INODE_SET_XTIME(i_mtime, &now, &inode);
 	EXT4_INODE_SET_XTIME(i_ctime, &now, &inode);
 	increment_version(&inode);
@@ -2054,7 +2074,7 @@ static void op_readlink(fuse_req_t req, fuse_ino_t fino)
 	buf[len] = 0;
 
 	if (fuse4fs_is_writeable(ff)) {
-		ret = update_atime(fs, ino);
+		ret = fuse4fs_update_atime(ff, ino);
 		if (ret)
 			goto out;
 	}
@@ -2323,7 +2343,7 @@ static void op_mknod(fuse_req_t req, fuse_ino_t fino, const char *name,
 		goto out2;
 	}
 
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse4fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -2346,7 +2366,7 @@ static void op_mknod(fuse_req_t req, fuse_ino_t fino, const char *name,
 	}
 
 	inode.i_generation = ff->next_generation++;
-	init_times(&inode);
+	fuse4fs_init_timestamps(ff, &inode);
 	err = fuse4fs_write_inode(fs, child, &inode);
 	if (err) {
 		ret = translate_error(fs, child, err);
@@ -2408,7 +2428,7 @@ static void op_mkdir(fuse_req_t req, fuse_ino_t fino, const char *name,
 		goto out2;
 	}
 
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse4fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -2434,7 +2454,7 @@ static void op_mkdir(fuse_req_t req, fuse_ino_t fino, const char *name,
 	if (parent_sgid)
 		inode.i_mode |= S_ISGID;
 	inode.i_generation = ff->next_generation++;
-	init_times(&inode);
+	fuse4fs_init_timestamps(ff, &inode);
 
 	err = fuse4fs_write_inode(fs, child, &inode);
 	if (err) {
@@ -2775,7 +2795,7 @@ static int fuse4fs_remove_inode(struct fuse4fs *ff, ext2_ino_t ino)
 		inode.i_links_count--;
 	}
 
-	ret = update_ctime(fs, ino, &inode);
+	ret = fuse4fs_update_ctime(ff, ino, &inode);
 	if (ret)
 		return ret;
 
@@ -2846,7 +2866,7 @@ static int fuse4fs_unlink(struct fuse4fs *ff, ext2_ino_t parent,
 		goto out;
 	}
 
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse4fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out;
 out:
@@ -2985,7 +3005,7 @@ static int fuse4fs_rmdir(struct fuse4fs *ff, ext2_ino_t parent,
 		}
 		if (inode.i_links_count > 1)
 			inode.i_links_count--;
-		ret = update_mtime(fs, rds.parent, &inode);
+		ret = fuse4fs_update_mtime(ff, rds.parent, &inode);
 		if (ret)
 			goto out;
 		err = fuse4fs_write_inode(fs, rds.parent, &inode);
@@ -3089,7 +3109,7 @@ static void op_symlink(fuse_req_t req, const char *target, fuse_ino_t fino,
 	}
 
 	/* Update parent dir's mtime */
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse4fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -3112,7 +3132,7 @@ static void op_symlink(fuse_req_t req, const char *target, fuse_ino_t fino,
 	fuse4fs_set_uid(&inode, ctxt->uid);
 	fuse4fs_set_gid(&inode, gid);
 	inode.i_generation = ff->next_generation++;
-	init_times(&inode);
+	fuse4fs_init_timestamps(ff, &inode);
 
 	err = fuse4fs_write_inode(fs, child, &inode);
 	if (err) {
@@ -3303,11 +3323,11 @@ static void op_rename(fuse_req_t req, fuse_ino_t from_parent, const char *from,
 	}
 
 	/* Update timestamps */
-	ret = update_ctime(fs, from_ino, NULL);
+	ret = fuse4fs_update_ctime(ff, from_ino, NULL);
 	if (ret)
 		goto out;
 
-	ret = update_mtime(fs, to_dir_ino, NULL);
+	ret = fuse4fs_update_mtime(ff, to_dir_ino, NULL);
 	if (ret)
 		goto out;
 
@@ -3381,7 +3401,7 @@ static void op_link(fuse_req_t req, fuse_ino_t child_fino,
 	}
 
 	inode.i_links_count++;
-	ret = update_ctime(fs, child, &inode);
+	ret = fuse4fs_update_ctime(ff, child, &inode);
 	if (ret)
 		goto out2;
 
@@ -3398,7 +3418,7 @@ static void op_link(fuse_req_t req, fuse_ino_t child_fino,
 		goto out2;
 	}
 
-	ret = update_mtime(fs, parent, NULL);
+	ret = fuse4fs_update_mtime(ff, parent, NULL);
 	if (ret)
 		goto out2;
 
@@ -3634,7 +3654,7 @@ static int fuse4fs_truncate(struct fuse4fs *ff, ext2_ino_t ino, off_t new_size)
 	if (err)
 		return translate_error(fs, ino, err);
 
-	ret = update_mtime(fs, ino, NULL);
+	ret = fuse4fs_update_mtime(ff, ino, NULL);
 	if (ret)
 		return ret;
 
@@ -3836,7 +3856,7 @@ static void op_read(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 	}
 
 	if (fh->check_flags != X_OK && fuse4fs_is_writeable(ff)) {
-		ret = update_atime(fs, fh->ino);
+		ret = fuse4fs_update_atime(ff, fh->ino);
 		if (ret)
 			goto out;
 	}
@@ -3910,7 +3930,7 @@ static void op_write(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 		goto out;
 	}
 
-	ret = update_mtime(fs, fh->ino, NULL);
+	ret = fuse4fs_update_mtime(ff, fh->ino, NULL);
 	if (ret)
 		goto out;
 
@@ -4357,7 +4377,7 @@ static void op_setxattr(fuse_req_t req, fuse_ino_t fino, const char *key,
 		goto out2;
 	}
 
-	ret = update_ctime(fs, ino, NULL);
+	ret = fuse4fs_update_ctime(ff, ino, NULL);
 out2:
 	err = ext2fs_xattrs_close(&h);
 	if (!ret && err)
@@ -4451,7 +4471,7 @@ static void op_removexattr(fuse_req_t req, fuse_ino_t fino, const char *key)
 		goto out2;
 	}
 
-	ret = update_ctime(fs, ino, NULL);
+	ret = fuse4fs_update_ctime(ff, ino, NULL);
 out2:
 	err = ext2fs_xattrs_close(&h);
 	if (err && !ret)
@@ -4598,7 +4618,7 @@ static void __op_readdir(fuse_req_t req, fuse_ino_t fino, size_t size,
 	}
 
 	if (fuse4fs_is_writeable(ff)) {
-		ret = update_atime(i.fs, fh->ino);
+		ret = fuse4fs_update_atime(i.ff, fh->ino);
 		if (ret)
 			goto out;
 	}
@@ -4698,7 +4718,7 @@ static void op_create(fuse_req_t req, fuse_ino_t fino, const char *name,
 			goto out2;
 		}
 
-		ret = update_mtime(fs, parent, NULL);
+		ret = fuse4fs_update_mtime(ff, parent, NULL);
 		if (ret)
 			goto out2;
 	} else {
@@ -4739,7 +4759,7 @@ static void op_create(fuse_req_t req, fuse_ino_t fino, const char *name,
 	}
 
 	inode.i_generation = ff->next_generation++;
-	init_times(&inode);
+	fuse4fs_init_timestamps(ff, &inode);
 	err = fuse4fs_write_inode(fs, child, &inode);
 	if (err) {
 		ret = translate_error(fs, child, err);
@@ -4818,7 +4838,7 @@ static int fuse4fs_utimens(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 	int ret = 0;
 
 	if (to_set & (FUSE_SET_ATTR_ATIME_NOW | FUSE_SET_ATTR_MTIME_NOW))
-		get_now(&now);
+		fuse4fs_get_now(ff, &now);
 
 	if (to_set & FUSE_SET_ATTR_ATIME_NOW) {
 		atime = now;
@@ -4956,7 +4976,7 @@ static void op_setattr(fuse_req_t req, fuse_ino_t fino, struct stat *attr,
 	}
 
 	/* Update ctime for any attribute change */
-	ret = update_ctime(fs, ino, &inode);
+	ret = fuse4fs_update_ctime(ff, ino, &inode);
 	if (ret)
 		goto out;
 
@@ -5038,7 +5058,7 @@ static int ioctl_setflags(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 	if (ret)
 		return ret;
 
-	ret = update_ctime(fs, fh->ino, &inode);
+	ret = fuse4fs_update_ctime(ff, fh->ino, &inode);
 	if (ret)
 		return ret;
 
@@ -5091,7 +5111,7 @@ static int ioctl_setversion(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 
 	inode.i_generation = *indata;
 
-	ret = update_ctime(fs, fh->ino, &inode);
+	ret = fuse4fs_update_ctime(ff, fh->ino, &inode);
 	if (ret)
 		return ret;
 
@@ -5227,7 +5247,7 @@ static int ioctl_fssetxattr(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 	if (ext2fs_inode_includes(inode_size, i_projid))
 		inode.i_projid = fsx->fsx_projid;
 
-	ret = update_ctime(fs, fh->ino, &inode);
+	ret = fuse4fs_update_ctime(ff, fh->ino, &inode);
 	if (ret)
 		return ret;
 
@@ -5520,7 +5540,7 @@ static int fuse4fs_allocate_range(struct fuse4fs *ff,
 		}
 	}
 
-	err = update_mtime(fs, fh->ino, &inode);
+	err = fuse4fs_update_mtime(ff, fh->ino, &inode);
 	if (err)
 		return err;
 
@@ -5693,7 +5713,7 @@ static int fuse4fs_punch_range(struct fuse4fs *ff,
 			return translate_error(fs, fh->ino, err);
 	}
 
-	err = update_mtime(fs, fh->ino, &inode);
+	err = fuse4fs_update_mtime(ff, fh->ino, &inode);
 	if (err)
 		return err;
 
@@ -7819,7 +7839,7 @@ static int __translate_error(ext2_filsys fs, ext2_ino_t ino, errcode_t err,
 			error_message(err), func, line);
 
 	/* Make a note in the error log */
-	get_now(&now);
+	fuse4fs_get_now(ff, &now);
 	ext2fs_set_tstamp(fs->super, s_last_error_time, now.tv_sec);
 	fs->super->s_last_error_ino = ino;
 	fs->super->s_last_error_line = line;
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index aedd1add48db82..fa4359133a79fc 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -662,8 +662,24 @@ static inline void fuse2fs_dump_extents(struct fuse2fs *ff, ext2_ino_t ino,
 	ext2fs_extent_free(extents);
 }
 
-static void get_now(struct timespec *now)
+static void fuse2fs_get_now(struct fuse2fs *ff, struct timespec *now)
 {
+#ifdef CLOCK_REALTIME_COARSE
+	/*
+	 * In iomap mode, the kernel is responsible for maintaining timestamps
+	 * because file writes don't upcall to fuse2fs.  The kernel's predicate
+	 * for deciding if [cm]time should be updated bases its decisions off
+	 * [cm]time being an exact match for the coarse clock (instead of
+	 * checking that [cm]time < coarse_clock) which means that fuse2fs
+	 * setting a fine-grained timestamp that is slightly ahead of the
+	 * coarse clock can result in timestamps appearing to go backwards.
+	 * generic/423 doesn't like seeing btime > ctime from statx, so we'll
+	 * use the coarse clock in iomap mode.
+	 */
+	if (fuse2fs_iomap_enabled(ff) &&
+	    !clock_gettime(CLOCK_REALTIME_COARSE, now))
+		return;
+#endif
 #ifdef CLOCK_REALTIME
 	if (!clock_gettime(CLOCK_REALTIME, now))
 		return;
@@ -691,7 +707,7 @@ static void fuse2fs_init_timestamps(struct fuse2fs *ff, ext2_ino_t ino,
 {
 	struct timespec now;
 
-	get_now(&now);
+	fuse2fs_get_now(ff, &now);
 	EXT4_INODE_SET_XTIME(i_atime, &now, inode);
 	EXT4_INODE_SET_XTIME(i_ctime, &now, inode);
 	EXT4_INODE_SET_XTIME(i_mtime, &now, inode);
@@ -710,7 +726,7 @@ static int fuse2fs_update_ctime(struct fuse2fs *ff, ext2_ino_t ino,
 	struct timespec now;
 	struct ext2_inode_large inode;
 
-	get_now(&now);
+	fuse2fs_get_now(ff, &now);
 
 	/* If user already has a inode buffer, just update that */
 	if (pinode) {
@@ -756,7 +772,7 @@ static int fuse2fs_update_atime(struct fuse2fs *ff, ext2_ino_t ino)
 	pinode = &inode;
 	EXT4_INODE_GET_XTIME(i_atime, &atime, pinode);
 	EXT4_INODE_GET_XTIME(i_mtime, &mtime, pinode);
-	get_now(&now);
+	fuse2fs_get_now(ff, &now);
 
 	datime = atime.tv_sec + ((double)atime.tv_nsec / NSEC_PER_SEC);
 	dmtime = mtime.tv_sec + ((double)mtime.tv_nsec / NSEC_PER_SEC);
@@ -791,7 +807,7 @@ static int fuse2fs_update_mtime(struct fuse2fs *ff, ext2_ino_t ino,
 	struct timespec now;
 
 	if (pinode) {
-		get_now(&now);
+		fuse2fs_get_now(ff, &now);
 		EXT4_INODE_SET_XTIME(i_mtime, &now, pinode);
 		EXT4_INODE_SET_XTIME(i_ctime, &now, pinode);
 		increment_version(pinode);
@@ -806,7 +822,7 @@ static int fuse2fs_update_mtime(struct fuse2fs *ff, ext2_ino_t ino,
 	if (err)
 		return translate_error(fs, ino, err);
 
-	get_now(&now);
+	fuse2fs_get_now(ff, &now);
 	EXT4_INODE_SET_XTIME(i_mtime, &now, &inode);
 	EXT4_INODE_SET_XTIME(i_ctime, &now, &inode);
 	increment_version(&inode);
@@ -4548,9 +4564,9 @@ static int op_utimens(const char *path, const struct timespec ctv[2],
 	tv[1] = ctv[1];
 #ifdef UTIME_NOW
 	if (tv[0].tv_nsec == UTIME_NOW)
-		get_now(tv);
+		fuse2fs_get_now(ff, tv);
 	if (tv[1].tv_nsec == UTIME_NOW)
-		get_now(tv + 1);
+		fuse2fs_get_now(ff, tv + 1);
 #endif /* UTIME_NOW */
 #ifdef UTIME_OMIT
 	if (tv[0].tv_nsec != UTIME_OMIT)
@@ -7259,7 +7275,7 @@ static int __translate_error(ext2_filsys fs, ext2_ino_t ino, errcode_t err,
 			error_message(err), func, line);
 
 	/* Make a note in the error log */
-	get_now(&now);
+	fuse2fs_get_now(ff, &now);
 	ext2fs_set_tstamp(fs->super, s_last_error_time, now.tv_sec);
 	fs->super->s_last_error_ino = ino;
 	fs->super->s_last_error_line = line;

[PATCH 07/10] fuse2fs: add tracing for retrieving timestamps

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Add tracing for retrieving timestamps so we can debug the weird
behavior.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 misc/fuse2fs.c |   20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)


diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index fa4359133a79fc..00dafec79f7766 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1580,9 +1580,11 @@ static void *op_init(struct fuse_conn_info *conn,
 	return ff;
 }
 
-static int stat_inode(ext2_filsys fs, ext2_ino_t ino, struct stat *statbuf)
+static int fuse2fs_stat(struct fuse2fs *ff, ext2_ino_t ino,
+			struct stat *statbuf)
 {
 	struct ext2_inode_large inode;
+	ext2_filsys fs = ff->fs;
 	dev_t fakedev = 0;
 	errcode_t err;
 	int ret = 0;
@@ -1621,6 +1623,13 @@ static int stat_inode(ext2_filsys fs, ext2_ino_t ino, struct stat *statbuf)
 #else
 	statbuf->st_ctime = tv.tv_sec;
 #endif
+
+	dbg_printf(ff, "%s: ino=%d atime=%lld.%ld mtime=%lld.%ld ctime=%lld.%ld\n",
+		   __func__, ino,
+		   (long long int)statbuf->st_atim.tv_sec, statbuf->st_atim.tv_nsec,
+		   (long long int)statbuf->st_mtim.tv_sec, statbuf->st_mtim.tv_nsec,
+		   (long long int)statbuf->st_ctim.tv_sec, statbuf->st_ctim.tv_nsec);
+
 	if (LINUX_S_ISCHR(inode.i_mode) ||
 	    LINUX_S_ISBLK(inode.i_mode)) {
 		if (inode.i_block[0])
@@ -1667,16 +1676,15 @@ static int op_getattr(const char *path, struct stat *statbuf,
 		      struct fuse_file_info *fi)
 {
 	struct fuse2fs *ff = fuse2fs_get();
-	ext2_filsys fs;
 	ext2_ino_t ino;
 	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
-	fs = fuse2fs_start(ff);
+	fuse2fs_start(ff);
 	ret = fuse2fs_file_ino(ff, path, fi, &ino);
 	if (ret)
 		goto out;
-	ret = stat_inode(fs, ino, statbuf);
+	ret = fuse2fs_stat(ff, ino, statbuf);
 out:
 	fuse2fs_finish(ff, ret);
 	return ret;
@@ -3409,7 +3417,7 @@ static int fuse2fs_file_uses_iomap(struct fuse2fs *ff, ext2_ino_t ino)
 	if (!fuse2fs_iomap_enabled(ff))
 		return 0;
 
-	ret = stat_inode(ff->fs, ino, &statbuf);
+	ret = fuse2fs_stat(ff, ino, &statbuf);
 	if (ret)
 		return ret;
 
@@ -4311,7 +4319,7 @@ static int op_readdir_iter(ext2_ino_t dir EXT2FS_ATTR((unused)),
 			(unsigned long long)i->dirpos);
 
 	if (i->flags == FUSE_READDIR_PLUS) {
-		ret = stat_inode(i->fs, dirent->inode, &stat);
+		ret = fuse2fs_stat(i->ff, dirent->inode, &stat);
 		if (ret)
 			return DIRENT_ABORT;
 	}

[PATCH 08/10] fuse2fs: enable syncfs

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Enable syncfs calls in fuse2fs.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   39 ++++++++++++++++++++++++++++++++++++++-
 misc/fuse2fs.c    |   36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+), 1 deletion(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 5673a545b06b31..25c19c0f0deca0 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -1993,7 +1993,7 @@ static int fuse4fs_statx(struct fuse4fs *ff, ext2_ino_t ino, int statx_mask,
 static void op_statx(fuse_req_t req, fuse_ino_t fino, int flags, int mask,
 		     struct fuse_file_info *fi)
 {
-	struct statx stx;
+	struct statx stx = { };
 	struct fuse4fs *ff = fuse4fs_get(req);
 	ext2_ino_t ino;
 	int ret = 0;
@@ -5775,6 +5775,40 @@ static void op_fallocate(fuse_req_t req, fuse_ino_t fino EXT2FS_ATTR((unused)),
 }
 #endif /* SUPPORT_FALLOCATE */
 
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
+static void op_syncfs(fuse_req_t req, fuse_ino_t ino)
+{
+	struct fuse4fs *ff = fuse4fs_get(req);
+	ext2_filsys fs;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE4FS_CHECK_CONTEXT(req);
+	fs = fuse4fs_start(ff);
+
+	if (ff->opstate == F4OP_WRITABLE) {
+		if (fs->super->s_error_count)
+			fs->super->s_state |= EXT2_ERROR_FS;
+		ext2fs_mark_super_dirty(fs);
+		err = ext2fs_set_gdt_csum(fs);
+		if (err) {
+			ret = translate_error(fs, 0, err);
+			goto out_unlock;
+		}
+
+		err = ext2fs_flush2(fs, 0);
+		if (err) {
+			ret = translate_error(fs, 0, err);
+			goto out_unlock;
+		}
+	}
+
+out_unlock:
+	fuse4fs_finish(ff, ret);
+	fuse_reply_err(req, -ret);
+}
+#endif
+
 #ifdef HAVE_FUSE_IOMAP
 static void fuse4fs_iomap_hole(struct fuse4fs *ff, struct fuse_file_iomap *iomap,
 			       off_t pos, uint64_t count)
@@ -7063,6 +7097,9 @@ static struct fuse_lowlevel_ops fs_ops = {
 #if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 18)
 	.statx = op_statx,
 #endif
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
+	.syncfs = op_syncfs,
+#endif
 #ifdef HAVE_FUSE_IOMAP
 	.iomap_begin = op_iomap_begin,
 	.iomap_end = op_iomap_end,
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 00dafec79f7766..d4f1825dd695ad 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -5331,6 +5331,41 @@ static int op_fallocate(const char *path EXT2FS_ATTR((unused)), int mode,
 }
 #endif /* SUPPORT_FALLOCATE */
 
+#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
+static int op_syncfs(const char *path)
+{
+	struct fuse2fs *ff = fuse2fs_get();
+	ext2_filsys fs;
+	errcode_t err;
+	int ret = 0;
+
+	FUSE2FS_CHECK_CONTEXT(ff);
+	dbg_printf(ff, "%s: path=%s\n", __func__, path);
+	fs = fuse2fs_start(ff);
+
+	if (ff->opstate == F2OP_WRITABLE) {
+		if (fs->super->s_error_count)
+			fs->super->s_state |= EXT2_ERROR_FS;
+		ext2fs_mark_super_dirty(fs);
+		err = ext2fs_set_gdt_csum(fs);
+		if (err) {
+			ret = translate_error(fs, 0, err);
+			goto out_unlock;
+		}
+
+		err = ext2fs_flush2(fs, 0);
+		if (err) {
+			ret = translate_error(fs, 0, err);
+			goto out_unlock;
+		}
+	}
+
+out_unlock:
+	fuse2fs_finish(ff, ret);
+	return ret;
+}
+#endif
+
 #ifdef HAVE_FUSE_IOMAP
 static void fuse2fs_iomap_hole(struct fuse2fs *ff, struct fuse_file_iomap *iomap,
 			       off_t pos, uint64_t count)
@@ -6611,6 +6646,7 @@ static struct fuse_operations fs_ops = {
 #endif
 #if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
 	.getattr_iflags = op_getattr_iflags,
+	.syncfs = op_syncfs,
 #endif
 #ifdef HAVE_FUSE_IOMAP
 	.iomap_begin = op_iomap_begin,

[PATCH 09/10] fuse2fs: skip the gdt write in op_destroy if syncfs is working

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

As an umount-time performance enhancement, don't bother to write the
group descriptor tables in op_destroy if we know that op_syncfs will do
it for us.  That only happens if iomap is enabled.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   19 ++++++++++++++++---
 misc/fuse2fs.c    |   19 ++++++++++++++++---
 2 files changed, 32 insertions(+), 6 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 25c19c0f0deca0..4f5618e64a93c3 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -268,6 +268,7 @@ struct fuse4fs {
 	int noblkdev;
 	int translate_inums;
 	int iomap_passthrough_options;
+	int write_gdt_on_destroy;
 
 	enum fuse4fs_opstate opstate;
 	int logfd;
@@ -1475,9 +1476,11 @@ static void op_destroy(void *userdata)
 		if (fs->super->s_error_count)
 			fs->super->s_state |= EXT2_ERROR_FS;
 		ext2fs_mark_super_dirty(fs);
-		err = ext2fs_set_gdt_csum(fs);
-		if (err)
-			translate_error(fs, 0, err);
+		if (ff->write_gdt_on_destroy) {
+			err = ext2fs_set_gdt_csum(fs);
+			if (err)
+				translate_error(fs, 0, err);
+		}
 
 		err = ext2fs_flush2(fs, 0);
 		if (err)
@@ -5803,6 +5806,15 @@ static void op_syncfs(fuse_req_t req, fuse_ino_t ino)
 		}
 	}
 
+	/*
+	 * When iomap is enabled, the kernel will call syncfs right before
+	 * calling the destroy method.  If any syncfs succeeds, then we know
+	 * that there will be a last syncfs and that it will write the GDT, so
+	 * destroy doesn't need to waste time doing that.
+	 */
+	if (fuse4fs_iomap_enabled(ff))
+		ff->write_gdt_on_destroy = 0;
+
 out_unlock:
 	fuse4fs_finish(ff, ret);
 	fuse_reply_err(req, -ret);
@@ -7497,6 +7509,7 @@ int main(int argc, char *argv[])
 		.iomap_dev = FUSE_IOMAP_DEV_NULL,
 #endif
 		.translate_inums = 1,
+		.write_gdt_on_destroy = 1,
 	};
 	errcode_t err;
 	FILE *orig_stderr = stderr;
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index d4f1825dd695ad..b193e0b2c06b69 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -261,6 +261,7 @@ struct fuse2fs {
 	int unmount_in_destroy;
 	int noblkdev;
 	int iomap_passthrough_options;
+	int write_gdt_on_destroy;
 
 	enum fuse2fs_opstate opstate;
 	int logfd;
@@ -1301,9 +1302,11 @@ static void op_destroy(void *p EXT2FS_ATTR((unused)))
 		if (fs->super->s_error_count)
 			fs->super->s_state |= EXT2_ERROR_FS;
 		ext2fs_mark_super_dirty(fs);
-		err = ext2fs_set_gdt_csum(fs);
-		if (err)
-			translate_error(fs, 0, err);
+		if (ff->write_gdt_on_destroy) {
+			err = ext2fs_set_gdt_csum(fs);
+			if (err)
+				translate_error(fs, 0, err);
+		}
 
 		err = ext2fs_flush2(fs, 0);
 		if (err)
@@ -5360,6 +5363,15 @@ static int op_syncfs(const char *path)
 		}
 	}
 
+	/*
+	 * When iomap is enabled, the kernel will call syncfs right before
+	 * calling the destroy method.  If any syncfs succeeds, then we know
+	 * that there will be a last syncfs and that it will write the GDT, so
+	 * destroy doesn't need to waste time doing that.
+	 */
+	if (fuse2fs_iomap_enabled(ff))
+		ff->write_gdt_on_destroy = 0;
+
 out_unlock:
 	fuse2fs_finish(ff, ret);
 	return ret;
@@ -6944,6 +6956,7 @@ int main(int argc, char *argv[])
 		.iomap_state = IOMAP_UNKNOWN,
 		.iomap_dev = FUSE_IOMAP_DEV_NULL,
 #endif
+		.write_gdt_on_destroy = 1,
 	};
 	errcode_t err;
 	FILE *orig_stderr = stderr;

[PATCH 10/10] fuse2fs: set sync, immutable, and append at file load time

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Convey these three inode flags to the kernel when we're loading a file.
This way the kernel can advertise and enforce those flags so that the
fuse server doesn't have to.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   10 ++++++++++
 misc/fuse2fs.c    |   53 ++++++++++++++++++++++++++++++++++++++---------------
 2 files changed, 48 insertions(+), 15 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 4f5618e64a93c3..a7709a7e6fb699 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -1800,6 +1800,16 @@ static int fuse4fs_stat_inode(struct fuse4fs *ff, ext2_ino_t ino,
 	entry->entry_timeout = FUSE4FS_ATTR_TIMEOUT;
 
 	fstat->iflags = 0;
+
+	if (inodep->i_flags & EXT2_SYNC_FL)
+		fstat->iflags |= FUSE_IFLAG_SYNC;
+
+	if (inodep->i_flags & EXT2_IMMUTABLE_FL)
+		fstat->iflags |= FUSE_IFLAG_IMMUTABLE;
+
+	if (inodep->i_flags & EXT2_APPEND_FL)
+		fstat->iflags |= FUSE_IFLAG_APPEND;
+
 #ifdef HAVE_FUSE_IOMAP
 	if (fuse4fs_iomap_enabled(ff)) {
 		fstat->iflags |= FUSE_IFLAG_IOMAP;
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index b193e0b2c06b69..260d1b77e3f24b 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1584,7 +1584,7 @@ static void *op_init(struct fuse_conn_info *conn,
 }
 
 static int fuse2fs_stat(struct fuse2fs *ff, ext2_ino_t ino,
-			struct stat *statbuf)
+			struct stat *statbuf, unsigned int *iflags)
 {
 	struct ext2_inode_large inode;
 	ext2_filsys fs = ff->fs;
@@ -1641,6 +1641,7 @@ static int fuse2fs_stat(struct fuse2fs *ff, ext2_ino_t ino,
 			statbuf->st_rdev = inode.i_block[1];
 	}
 
+	*iflags = inode.i_flags;
 	return ret;
 }
 
@@ -1675,22 +1676,31 @@ static int __fuse2fs_file_ino(struct fuse2fs *ff, const char *path,
 # define fuse2fs_file_ino(ff, path, fp, inop) \
 	__fuse2fs_file_ino((ff), (path), (fp), (inop), __func__, __LINE__)
 
+static int fuse2fs_getattr(struct fuse2fs *ff, const char *path,
+			   struct stat *statbuf, struct fuse_file_info *fi,
+			   unsigned int *iflags)
+{
+	ext2_ino_t ino;
+	int ret = 0;
+
+	FUSE2FS_CHECK_CONTEXT(ff);
+	fuse2fs_start(ff);
+	ret = fuse2fs_file_ino(ff, path, fi, &ino);
+	if (ret)
+		goto out;
+	ret = fuse2fs_stat(ff, ino, statbuf, iflags);
+out:
+	fuse2fs_finish(ff, ret);
+	return ret;
+}
+
 static int op_getattr(const char *path, struct stat *statbuf,
 		      struct fuse_file_info *fi)
 {
 	struct fuse2fs *ff = fuse2fs_get();
-	ext2_ino_t ino;
-	int ret = 0;
+	unsigned int dontcare;
 
-	FUSE2FS_CHECK_CONTEXT(ff);
-	fuse2fs_start(ff);
-	ret = fuse2fs_file_ino(ff, path, fi, &ino);
-	if (ret)
-		goto out;
-	ret = fuse2fs_stat(ff, ino, statbuf);
-out:
-	fuse2fs_finish(ff, ret);
-	return ret;
+	return fuse2fs_getattr(ff, path, statbuf, fi, &dontcare);
 }
 
 #if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
@@ -1698,11 +1708,21 @@ static int op_getattr_iflags(const char *path, struct stat *statbuf,
 			     unsigned int *iflags, struct fuse_file_info *fi)
 {
 	struct fuse2fs *ff = fuse2fs_get();
-	int ret = op_getattr(path, statbuf, fi);
+	unsigned int i_flags;
+	int ret = fuse2fs_getattr(ff, path, statbuf, fi, &i_flags);
 
 	if (ret)
 		return ret;
 
+	if (i_flags & EXT2_IMMUTABLE_FL)
+		*iflags |= FUSE_IFLAG_IMMUTABLE;
+
+	if (i_flags & EXT2_SYNC_FL)
+		*iflags |= FUSE_IFLAG_SYNC;
+
+	if (i_flags & EXT2_APPEND_FL)
+		*iflags |= FUSE_IFLAG_APPEND;
+
 	if (fuse_fs_can_enable_iomap(statbuf)) {
 		*iflags |= FUSE_IFLAG_IOMAP;
 
@@ -3415,12 +3435,13 @@ static int fuse2fs_punch_posteof(struct fuse2fs *ff, ext2_ino_t ino,
 static int fuse2fs_file_uses_iomap(struct fuse2fs *ff, ext2_ino_t ino)
 {
 	struct stat statbuf;
+	unsigned int dontcare;
 	int ret;
 
 	if (!fuse2fs_iomap_enabled(ff))
 		return 0;
 
-	ret = fuse2fs_stat(ff, ino, &statbuf);
+	ret = fuse2fs_stat(ff, ino, &statbuf, &dontcare);
 	if (ret)
 		return ret;
 
@@ -4322,7 +4343,9 @@ static int op_readdir_iter(ext2_ino_t dir EXT2FS_ATTR((unused)),
 			(unsigned long long)i->dirpos);
 
 	if (i->flags == FUSE_READDIR_PLUS) {
-		ret = fuse2fs_stat(i->ff, dirent->inode, &stat);
+		unsigned int dontcare;
+
+		ret = fuse2fs_stat(i->ff, dirent->inode, &stat, &dontcare);
 		if (ret)
 			return DIRENT_ABORT;
 	}

[PATCH 1/3] fuse2fs: enable caching of iomaps

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Cache the iomaps we generate in the kernel for better performance.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   25 +++++++++++++++++++++++++
 misc/fuse2fs.c    |   24 ++++++++++++++++++++++++
 2 files changed, 49 insertions(+)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index a7709a7e6fb699..6ab660b36d0472 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -284,6 +284,8 @@ struct fuse4fs {
 #ifdef STATX_WRITE_ATOMIC
 	unsigned int awu_min, awu_max;
 #endif
+	/* options set by fuse_opt_parse must be of type int */
+	int iomap_cache;
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -6373,6 +6375,24 @@ static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 	if (opflags & FUSE_IOMAP_OP_ATOMIC)
 		read.flags |= FUSE_IOMAP_F_ATOMIC_BIO;
 
+	/*
+	 * Cache the mapping in the kernel so that we can reuse them for
+	 * subsequent IO.
+	 */
+	if (ff->iomap_cache) {
+		ret = fuse_lowlevel_notify_iomap_upsert(ff->fuse, fino, ino,
+							&read, NULL);
+		if (ret) {
+			ret = translate_error(fs, ino, -ret);
+			goto out_unlock;
+		} else {
+			/* Tell the kernel to retry from cache */
+			read.type = FUSE_IOMAP_TYPE_RETRY_CACHE;
+			read.dev = FUSE_IOMAP_DEV_NULL;
+			read.addr = FUSE_IOMAP_NULL_ADDR;
+		}
+	}
+
 out_unlock:
 	fuse4fs_finish(ff, ret);
 	if (ret)
@@ -7183,6 +7203,10 @@ static struct fuse_opt fuse4fs_opts[] = {
 	FUSE4FS_OPT("timing",		timing,			1),
 #endif
 	FUSE4FS_OPT("noblkdev",		noblkdev,		1),
+#ifdef HAVE_FUSE_IOMAP
+	FUSE4FS_OPT("iomap_cache",	iomap_cache,		1),
+	FUSE4FS_OPT("noiomap_cache",	iomap_cache,		0),
+#endif
 
 #ifdef HAVE_FUSE_IOMAP
 #ifdef MS_LAZYTIME
@@ -7517,6 +7541,7 @@ int main(int argc, char *argv[])
 		.iomap_want = FT_DEFAULT,
 		.iomap_state = IOMAP_UNKNOWN,
 		.iomap_dev = FUSE_IOMAP_DEV_NULL,
+		.iomap_cache = 1,
 #endif
 		.translate_inums = 1,
 		.write_gdt_on_destroy = 1,
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 260d1b77e3f24b..14a1ceeea46a0b 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -277,6 +277,8 @@ struct fuse2fs {
 #ifdef STATX_WRITE_ATOMIC
 	unsigned int awu_min, awu_max;
 #endif
+	/* options set by fuse_opt_parse must be of type int */
+	int iomap_cache;
 #endif
 	unsigned int blockmask;
 	unsigned long offset;
@@ -5942,6 +5944,23 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 	if (opflags & FUSE_IOMAP_OP_ATOMIC)
 		read->flags |= FUSE_IOMAP_F_ATOMIC_BIO;
 
+	/*
+	 * Cache the mapping in the kernel so that we can reuse them for
+	 * subsequent IO.
+	 */
+	if (ff->iomap_cache) {
+		ret = fuse_fs_iomap_upsert(nodeid, attr_ino, read, NULL);
+		if (ret) {
+			ret = translate_error(fs, attr_ino, -ret);
+			goto out_unlock;
+		} else {
+			/* Tell the kernel to retry from cache */
+			read->type = FUSE_IOMAP_TYPE_RETRY_CACHE;
+			read->dev = FUSE_IOMAP_DEV_NULL;
+			read->addr = FUSE_IOMAP_NULL_ADDR;
+		}
+	}
+
 out_unlock:
 	fuse2fs_finish(ff, ret);
 	return ret;
@@ -6744,6 +6763,10 @@ static struct fuse_opt fuse2fs_opts[] = {
 	FUSE2FS_OPT("timing",		timing,			1),
 #endif
 	FUSE2FS_OPT("noblkdev",		noblkdev,		1),
+#ifdef HAVE_FUSE_IOMAP
+	FUSE2FS_OPT("iomap_cache",	iomap_cache,		1),
+	FUSE2FS_OPT("noiomap_cache",	iomap_cache,		0),
+#endif
 
 #ifdef HAVE_FUSE_IOMAP
 #ifdef MS_LAZYTIME
@@ -6978,6 +7001,7 @@ int main(int argc, char *argv[])
 		.iomap_want = FT_DEFAULT,
 		.iomap_state = IOMAP_UNKNOWN,
 		.iomap_dev = FUSE_IOMAP_DEV_NULL,
+		.iomap_cache = 1,
 #endif
 		.write_gdt_on_destroy = 1,
 	};

[PATCH 2/3] fuse2fs: be smarter about caching iomaps

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

There's no point in caching iomaps when we're initiating a disk write to
an unwritten region -- we'll just replace the mapping in the ioend.
Save ourselves a bit of overhead by screening for that.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   27 ++++++++++++++++++++++++++-
 misc/fuse2fs.c    |   24 +++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 2 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 6ab660b36d0472..5c563eff1c38c1 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -6309,6 +6309,31 @@ static int fuse4fs_iomap_begin_write(struct fuse4fs *ff, ext2_ino_t ino,
 	return 0;
 }
 
+static inline int fuse4fs_should_cache_iomap(struct fuse4fs *ff,
+					     uint32_t opflags,
+					     const struct fuse_file_iomap *map)
+{
+	if (!ff->iomap_cache)
+		return 0;
+
+	/* XXX I think this is stupid */
+	return 1;
+
+	/*
+	 * Don't cache small unwritten extents that are being written to the
+	 * device because the overhead of keeping the cache updated will tank
+	 * performance.
+	 */
+	if ((opflags & (FUSE_IOMAP_OP_WRITE | FUSE_IOMAP_OP_DIRECT)) == 0)
+		return 1;
+	if (map->type != FUSE_IOMAP_TYPE_UNWRITTEN)
+		return 1;
+	if (map->length >= FUSE4FS_FSB_TO_B(ff, 16))
+		return 1;
+
+	return 0;
+}
+
 static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 			   off_t pos, uint64_t count, uint32_t opflags)
 {
@@ -6379,7 +6404,7 @@ static void op_iomap_begin(fuse_req_t req, fuse_ino_t fino, uint64_t dontcare,
 	 * Cache the mapping in the kernel so that we can reuse them for
 	 * subsequent IO.
 	 */
-	if (ff->iomap_cache) {
+	if (fuse4fs_should_cache_iomap(ff, opflags, &read)) {
 		ret = fuse_lowlevel_notify_iomap_upsert(ff->fuse, fino, ino,
 							&read, NULL);
 		if (ret) {
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 14a1ceeea46a0b..7a10b6cab87f7c 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -5876,6 +5876,28 @@ static int fuse2fs_iomap_begin_write(struct fuse2fs *ff, ext2_ino_t ino,
 	return 0;
 }
 
+static inline int fuse2fs_should_cache_iomap(struct fuse2fs *ff,
+					     uint32_t opflags,
+					     const struct fuse_file_iomap *map)
+{
+	if (!ff->iomap_cache)
+		return 0;
+
+	/*
+	 * Don't cache small unwritten extents that are being written to the
+	 * device because the overhead of keeping the cache updated will tank
+	 * performance.
+	 */
+	if ((opflags & (FUSE_IOMAP_OP_WRITE | FUSE_IOMAP_OP_DIRECT)) == 0)
+		return 1;
+	if (map->type != FUSE_IOMAP_TYPE_UNWRITTEN)
+		return 1;
+	if (map->length >= FUSE2FS_FSB_TO_B(ff, 16))
+		return 1;
+
+	return 0;
+}
+
 static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 			  off_t pos, uint64_t count, uint32_t opflags,
 			  struct fuse_file_iomap *read,
@@ -5948,7 +5970,7 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 	 * Cache the mapping in the kernel so that we can reuse them for
 	 * subsequent IO.
 	 */
-	if (ff->iomap_cache) {
+	if (fuse2fs_should_cache_iomap(ff, opflags, read)) {
 		ret = fuse_fs_iomap_upsert(nodeid, attr_ino, read, NULL);
 		if (ret) {
 			ret = translate_error(fs, attr_ino, -ret);

[PATCH 3/3] fuse2fs: enable iomap

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Now that iomap functionality is complete, enable this for users.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |    4 ----
 misc/fuse2fs.c    |    4 ----
 2 files changed, 8 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 5c563eff1c38c1..c4397fc365ced7 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -1652,10 +1652,6 @@ static inline int fuse_set_feature_flag(struct fuse_conn_info *conn,
 static void fuse4fs_iomap_enable(struct fuse_conn_info *conn,
 				 struct fuse4fs *ff)
 {
-	/* Don't let anyone touch iomap until the end of the patchset. */
-	ff->iomap_state = IOMAP_DISABLED;
-	return;
-
 	/* iomap only works with block devices */
 	if (ff->iomap_state != IOMAP_DISABLED && fuse4fs_on_bdev(ff) &&
 	    fuse_set_feature_flag(conn, FUSE_CAP_IOMAP)) {
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 7a10b6cab87f7c..5e4680ca023282 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1478,10 +1478,6 @@ static inline int fuse_set_feature_flag(struct fuse_conn_info *conn,
 static void fuse2fs_iomap_enable(struct fuse_conn_info *conn,
 				 struct fuse2fs *ff)
 {
-	/* Don't let anyone touch iomap until the end of the patchset. */
-	ff->iomap_state = IOMAP_DISABLED;
-	return;
-
 	/* iomap only works with block devices */
 	if (ff->iomap_state != IOMAP_DISABLED && fuse2fs_on_bdev(ff) &&
 	    fuse_set_feature_flag(conn, FUSE_CAP_IOMAP)) {

[PATCH 1/6] libsupport: add caching IO manager

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Start creating a caching IO manager so that we can have better caching
of metadata blocks in fuse2fs.  For now it's just a passthrough cache.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/iocache.h   |   17 +++
 lib/ext2fs/io_manager.c |    3 
 lib/support/Makefile.in |    6 +
 lib/support/iocache.c   |  306 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 331 insertions(+), 1 deletion(-)
 create mode 100644 lib/support/iocache.h
 create mode 100644 lib/support/iocache.c


diff --git a/lib/support/iocache.h b/lib/support/iocache.h
new file mode 100644
index 00000000000000..3c1d1df00e25bd
--- /dev/null
+++ b/lib/support/iocache.h
@@ -0,0 +1,17 @@
+/*
+ * iocache.h - IO cache
+ *
+ * Copyright (C) 2025 Oracle.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+#ifndef __IOCACHE_H__
+#define __IOCACHE_H__
+
+errcode_t iocache_set_backing_manager(io_manager manager);
+extern io_manager iocache_io_manager;
+
+#endif /* __IOCACHE_H__ */
diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
index c91fab4eb290d5..7a6a6bfedc8a1c 100644
--- a/lib/ext2fs/io_manager.c
+++ b/lib/ext2fs/io_manager.c
@@ -16,9 +16,12 @@
 #if HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
+#include <stdbool.h>
 
 #include "ext2_fs.h"
 #include "ext2fs.h"
+#include "support/list.h"
+#include "support/cache.h"
 
 errcode_t io_channel_set_options(io_channel channel, const char *opts)
 {
diff --git a/lib/support/Makefile.in b/lib/support/Makefile.in
index 13d6f06f150afd..98a9bd42eef55e 100644
--- a/lib/support/Makefile.in
+++ b/lib/support/Makefile.in
@@ -14,6 +14,7 @@ MKDIR_P = @MKDIR_P@
 all::
 
 OBJS=		cstring.o \
+		iocache.o \
 		mkquota.o \
 		plausible.o \
 		profile.o \
@@ -42,7 +43,8 @@ SRCS=		$(srcdir)/argv_parse.c \
 		$(srcdir)/quotaio_v2.c \
 		$(srcdir)/dict.c \
 		$(srcdir)/devname.c \
-		$(srcdir)/cache.c
+		$(srcdir)/cache.c \
+		$(srcdir)/iocache.c
 
 LIBRARY= libsupport
 LIBDIR= support
@@ -187,3 +189,5 @@ devname.o: $(srcdir)/devname.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/devname.h $(srcdir)/nls-enable.h
 cache.o: $(srcdir)/cache.c $(top_builddir)/lib/config.h \
  $(srcdir)/cache.h $(srcdir)/list.h $(srcdir)/xbitops.h
+iocache.o: $(srcdir)/iocache.c $(top_builddir)/lib/config.h \
+ $(srcdir)/iocache.h $(srcdir)/cache.h $(srcdir)/list.h $(srcdir)/xbitops.h
diff --git a/lib/support/iocache.c b/lib/support/iocache.c
new file mode 100644
index 00000000000000..9870780d65ef61
--- /dev/null
+++ b/lib/support/iocache.c
@@ -0,0 +1,306 @@
+/*
+ * fuse4fs.c - FUSE low-level server for e2fsprogs.
+ *
+ * Copyright (C) 2025 Oracle.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+#include "config.h"
+#include "ext2fs/ext2_fs.h"
+#include "ext2fs/ext2fs.h"
+#include "ext2fs/ext2fsP.h"
+#include "support/iocache.h"
+
+#define IOCACHE_IO_CHANNEL_MAGIC	0x424F5254	/* BORT */
+
+static io_manager iocache_backing_manager;
+
+struct iocache_private_data {
+	int			magic;
+	io_channel		real;
+};
+
+static struct iocache_private_data *IOCACHE(io_channel channel)
+{
+	return (struct iocache_private_data *)channel->private_data;
+}
+
+static errcode_t iocache_read_error(io_channel channel, unsigned long block,
+				    int count, void *data, size_t size,
+				    int actual_bytes_read, errcode_t error)
+{
+	io_channel iocache_channel = channel->app_data;
+
+	return iocache_channel->read_error(iocache_channel, block, count, data,
+					   size, actual_bytes_read, error);
+}
+
+static errcode_t iocache_write_error(io_channel channel, unsigned long block,
+				     int count, const void *data, size_t size,
+				     int actual_bytes_written,
+				     errcode_t error)
+{
+	io_channel iocache_channel = channel->app_data;
+
+	return iocache_channel->write_error(iocache_channel, block, count, data,
+					    size, actual_bytes_written, error);
+}
+
+static errcode_t iocache_open(const char *name, int flags, io_channel *channel)
+{
+	io_channel	io = NULL;
+	io_channel	real;
+	struct iocache_private_data *data = NULL;
+	errcode_t	retval;
+
+	if (!name)
+		return EXT2_ET_BAD_DEVICE_NAME;
+	if (!iocache_backing_manager)
+		return EXT2_ET_INVALID_ARGUMENT;
+
+	retval = iocache_backing_manager->open(name, flags, &real);
+	if (retval)
+		return retval;
+
+	retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
+	if (retval)
+		goto out_backing;
+	memset(io, 0, sizeof(struct struct_io_channel));
+	io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
+
+	retval = ext2fs_get_mem(sizeof(struct iocache_private_data), &data);
+	if (retval)
+		goto out_channel;
+	memset(data, 0, sizeof(struct iocache_private_data));
+	data->magic = IOCACHE_IO_CHANNEL_MAGIC;
+
+	io->manager = iocache_io_manager;
+	retval = ext2fs_get_mem(strlen(name) + 1, &io->name);
+	if (retval)
+		goto out_data;
+
+	strcpy(io->name, name);
+	io->private_data = data;
+	io->block_size = real->block_size;
+	io->read_error = 0;
+	io->write_error = 0;
+	io->refcount = 1;
+	io->flags = real->flags;
+	data->real = real;
+	real->app_data = io;
+	real->read_error = iocache_read_error;
+	real->write_error = iocache_write_error;
+
+	*channel = io;
+	return 0;
+
+out_data:
+	ext2fs_free_mem(&data);
+out_channel:
+	ext2fs_free_mem(&io);
+out_backing:
+	io_channel_close(real);
+	return retval;
+}
+
+static errcode_t iocache_close(io_channel channel)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+	errcode_t	retval = 0;
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	if (--channel->refcount > 0)
+		return 0;
+	if (data->real)
+		retval = io_channel_close(data->real);
+	ext2fs_free_mem(&channel->private_data);
+	if (channel->name)
+		ext2fs_free_mem(&channel->name);
+	ext2fs_free_mem(&channel);
+
+	return retval;
+}
+
+static errcode_t iocache_set_blksize(io_channel channel, int blksize)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+	errcode_t retval;
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	retval = io_channel_set_blksize(data->real, blksize);
+	if (retval)
+		return retval;
+
+	channel->block_size = data->real->block_size;
+	return 0;
+}
+
+static errcode_t iocache_flush(io_channel channel)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_flush(data->real);
+}
+
+static errcode_t iocache_write_byte(io_channel channel, unsigned long offset,
+				    int count, const void *buf)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_write_byte(data->real, offset, count, buf);
+}
+
+static errcode_t iocache_set_option(io_channel channel, const char *option,
+				    const char *arg)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return data->real->manager->set_option(data->real, option, arg);
+}
+
+static errcode_t iocache_get_stats(io_channel channel, io_stats *io_stats)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return data->real->manager->get_stats(data->real, io_stats);
+}
+
+static errcode_t iocache_read_blk64(io_channel channel,
+				    unsigned long long block, int count,
+				    void *buf)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_read_blk64(data->real, block, count, buf);
+}
+
+static errcode_t iocache_write_blk64(io_channel channel,
+				     unsigned long long block, int count,
+				     const void *buf)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_write_blk64(data->real, block, count, buf);
+}
+
+static errcode_t iocache_read_blk(io_channel channel, unsigned long block,
+				  int count, void *buf)
+{
+	return iocache_read_blk64(channel, block, count, buf);
+}
+
+static errcode_t iocache_write_blk(io_channel channel, unsigned long block,
+				   int count, const void *buf)
+{
+	return iocache_write_blk64(channel, block, count, buf);
+}
+
+static errcode_t iocache_discard(io_channel channel, unsigned long long block,
+				 unsigned long long count)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_discard(data->real, block, count);
+}
+
+static errcode_t iocache_cache_readahead(io_channel channel,
+					 unsigned long long block,
+					 unsigned long long count)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_cache_readahead(data->real, block, count);
+}
+
+static errcode_t iocache_zeroout(io_channel channel, unsigned long long block,
+				 unsigned long long count)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_zeroout(data->real, block, count);
+}
+
+static errcode_t iocache_get_fd(io_channel channel, int *fd)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_get_fd(data->real, fd);
+}
+
+static errcode_t iocache_invalidate_blocks(io_channel channel,
+					   unsigned long long block,
+					   unsigned long long count)
+{
+	struct iocache_private_data *data = IOCACHE(channel);
+
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+
+	return io_channel_invalidate_blocks(data->real, block, count);
+}
+
+static struct struct_io_manager struct_iocache_manager = {
+	.magic			= EXT2_ET_MAGIC_IO_MANAGER,
+	.name			= "iocache I/O manager",
+	.open			= iocache_open,
+	.close			= iocache_close,
+	.set_blksize		= iocache_set_blksize,
+	.read_blk		= iocache_read_blk,
+	.write_blk		= iocache_write_blk,
+	.flush			= iocache_flush,
+	.write_byte		= iocache_write_byte,
+	.set_option		= iocache_set_option,
+	.get_stats		= iocache_get_stats,
+	.read_blk64		= iocache_read_blk64,
+	.write_blk64		= iocache_write_blk64,
+	.discard		= iocache_discard,
+	.cache_readahead	= iocache_cache_readahead,
+	.zeroout		= iocache_zeroout,
+	.get_fd			= iocache_get_fd,
+	.invalidate_blocks	= iocache_invalidate_blocks,
+};
+
+io_manager iocache_io_manager = &struct_iocache_manager;
+
+errcode_t iocache_set_backing_manager(io_manager manager)
+{
+	iocache_backing_manager = manager;
+	return 0;
+}

[PATCH 2/6] iocache: add the actual buffer cache

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Wire up buffer caching into our new caching IO manager.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/iocache.c |  469 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 447 insertions(+), 22 deletions(-)


diff --git a/lib/support/iocache.c b/lib/support/iocache.c
index 9870780d65ef61..ab879e85d18f2a 100644
--- a/lib/support/iocache.c
+++ b/lib/support/iocache.c
@@ -9,46 +9,288 @@
  * %End-Header%
  */
 #include "config.h"
+#include <assert.h>
+#include <stdbool.h>
+#include <pthread.h>
+#include <unistd.h>
 #include "ext2fs/ext2_fs.h"
 #include "ext2fs/ext2fs.h"
 #include "ext2fs/ext2fsP.h"
 #include "support/iocache.h"
+#include "support/list.h"
+#include "support/cache.h"
 
 #define IOCACHE_IO_CHANNEL_MAGIC	0x424F5254	/* BORT */
 
 static io_manager iocache_backing_manager;
 
+static inline uint64_t B_TO_FSBT(io_channel channel, uint64_t number) {
+	return number / channel->block_size;
+}
+
+static inline uint64_t B_TO_FSB(io_channel channel, uint64_t number) {
+	return (number + channel->block_size - 1) / channel->block_size;
+}
+
 struct iocache_private_data {
 	int			magic;
-	io_channel		real;
+	io_channel		real;		/* lower level io channel */
+	io_channel		channel;	/* cache channel */
+	struct cache		cache;
+	pthread_mutex_t		stats_lock;
+	struct struct_io_stats	io_stats;
+	unsigned long long	write_errors;
 };
 
+#define IOCACHEDATA(cache) \
+	(container_of(cache, struct iocache_private_data, cache))
+
 static struct iocache_private_data *IOCACHE(io_channel channel)
 {
 	return (struct iocache_private_data *)channel->private_data;
 }
 
-static errcode_t iocache_read_error(io_channel channel, unsigned long block,
-				    int count, void *data, size_t size,
-				    int actual_bytes_read, errcode_t error)
+struct iocache_buf {
+	struct cache_node	node;
+	struct list_head	list;
+	blk64_t			block;
+	void			*buf;
+	errcode_t		write_error;
+	unsigned int		uptodate:1;
+	unsigned int		dirty:1;
+};
+
+static inline void iocache_buf_lock(struct iocache_buf *ubuf)
 {
-	io_channel iocache_channel = channel->app_data;
+	pthread_mutex_lock(&ubuf->node.cn_mutex);
+}
 
-	return iocache_channel->read_error(iocache_channel, block, count, data,
-					   size, actual_bytes_read, error);
+static inline void iocache_buf_unlock(struct iocache_buf *ubuf)
+{
+	pthread_mutex_unlock(&ubuf->node.cn_mutex);
 }
 
-static errcode_t iocache_write_error(io_channel channel, unsigned long block,
-				     int count, const void *data, size_t size,
-				     int actual_bytes_written,
-				     errcode_t error)
+struct iocache_key {
+	blk64_t			block;
+};
+
+#define IOKEY(key)	((struct iocache_key *)(key))
+#define IOBUF(node)	(container_of((node), struct iocache_buf, node))
+
+static unsigned int
+iocache_hash(cache_key_t key, unsigned int hashsize, unsigned int hashshift)
 {
-	io_channel iocache_channel = channel->app_data;
+	uint64_t	hashval = IOKEY(key)->block;
+	uint64_t	tmp;
 
-	return iocache_channel->write_error(iocache_channel, block, count, data,
-					    size, actual_bytes_written, error);
+	tmp = hashval ^ (GOLDEN_RATIO_PRIME + hashval) / CACHE_LINE_SIZE;
+	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> hashshift);
+	return tmp % hashsize;
 }
 
+static int iocache_compare(struct cache_node *node, cache_key_t key)
+{
+	struct iocache_buf *ubuf = IOBUF(node);
+	struct iocache_key *ukey = IOKEY(key);
+
+	if (ubuf->block == ukey->block)
+		return CACHE_HIT;
+
+	return CACHE_MISS;
+}
+
+static struct cache_node *iocache_alloc_node(struct cache *cache,
+					     cache_key_t key)
+{
+	struct iocache_private_data *data = IOCACHEDATA(cache);
+	struct iocache_key *ukey = IOKEY(key);
+	struct iocache_buf *ubuf;
+	errcode_t retval;
+
+	retval = ext2fs_get_mem(sizeof(struct iocache_buf), &ubuf);
+	if (retval)
+		return NULL;
+	memset(ubuf, 0, sizeof(*ubuf));
+
+	retval = io_channel_alloc_buf(data->channel, 0, &ubuf->buf);
+	if (retval) {
+		free(ubuf);
+		return NULL;
+	}
+	memset(ubuf->buf, 0, data->channel->block_size);
+
+	INIT_LIST_HEAD(&ubuf->list);
+	ubuf->block = ukey->block;
+	return &ubuf->node;
+}
+
+static bool iocache_flush_node(struct cache *cache, struct cache_node *node)
+{
+	struct iocache_private_data *data = IOCACHEDATA(cache);
+	struct iocache_buf *ubuf = IOBUF(node);
+	errcode_t retval;
+
+	if (ubuf->dirty) {
+		retval = io_channel_write_blk64(data->real, ubuf->block, 1,
+						ubuf->buf);
+		if (retval) {
+			ubuf->write_error = retval;
+			data->write_errors++;
+		} else {
+			ubuf->dirty = 0;
+			ubuf->write_error = 0;
+		}
+	}
+
+	return ubuf->dirty;
+}
+
+static void iocache_relse(struct cache *cache, struct cache_node *node)
+{
+	struct iocache_buf *ubuf = IOBUF(node);
+
+	assert(!ubuf->dirty);
+
+	ext2fs_free_mem(&ubuf->buf);
+	ext2fs_free_mem(&ubuf);
+}
+
+static unsigned int iocache_bulkrelse(struct cache *cache,
+				      struct list_head *list)
+{
+	struct cache_node *cn, *n;
+	int count = 0;
+
+	if (list_empty(list))
+		return 0;
+
+	list_for_each_entry_safe(cn, n, list, cn_mru) {
+		iocache_relse(cache, cn);
+		count++;
+	}
+
+	return count;
+}
+
+/* Flush all dirty buffers in the cache to disk. */
+static errcode_t iocache_flush_cache(struct iocache_private_data *data)
+{
+	return cache_flush(&data->cache) ? 0 : EIO;
+}
+
+/* Flush all dirty buffers in this range of the cache to disk. */
+static errcode_t iocache_flush_range(struct iocache_private_data *data,
+				     blk64_t block, uint64_t count)
+{
+	uint64_t i;
+	bool still_dirty = false;
+
+	for (i = 0; i < count; i++) {
+		struct iocache_key ukey = {
+			.block = block + i,
+		};
+		struct cache_node *node;
+
+		cache_node_get(&data->cache, &ukey, CACHE_GET_INCORE,
+			       &node);
+		if (!node)
+			continue;
+
+		/* cache_flush holds cn_mutex across the node flush */
+		pthread_mutex_unlock(&node->cn_mutex);
+		still_dirty |= iocache_flush_node(&data->cache, node);
+		pthread_mutex_unlock(&node->cn_mutex);
+
+		cache_node_put(&data->cache, node);
+	}
+
+	return still_dirty ? EIO : 0;
+}
+
+static void iocache_add_list(struct cache *cache, struct cache_node *node,
+			     void *data)
+{
+	struct iocache_buf *ubuf = IOBUF(node);
+	struct list_head *list = data;
+
+	assert(node->cn_count == 0 || node->cn_count == 1);
+
+	iocache_buf_lock(ubuf);
+	cache_node_grab(cache, node);
+	list_add_tail(&ubuf->list, list);
+	iocache_buf_unlock(ubuf);
+}
+
+static void iocache_invalidate_bufs(struct iocache_private_data *data,
+				    struct list_head *list)
+{
+	struct iocache_buf *ubuf, *n;
+
+	list_for_each_entry_safe(ubuf, n, list, list) {
+		struct iocache_key ukey = {
+			.block = ubuf->block,
+		};
+
+		assert(ubuf->node.cn_count == 1);
+
+		iocache_buf_lock(ubuf);
+		ubuf->dirty = 0;
+		list_del_init(&ubuf->list);
+		iocache_buf_unlock(ubuf);
+
+		cache_node_put(&data->cache, &ubuf->node);
+		cache_node_purge(&data->cache, &ukey, &ubuf->node);
+	}
+}
+
+/*
+ * Remove all blocks from the cache.  Dirty contents are discarded.  Buffer
+ * refcounts must be zero!
+ */
+static void iocache_invalidate_cache(struct iocache_private_data *data)
+{
+	LIST_HEAD(list);
+
+	cache_walk(&data->cache, iocache_add_list, &list);
+	iocache_invalidate_bufs(data, &list);
+}
+
+/*
+ * Remove a range of blocks from the cache.  Dirty contents are discarded.
+ * Buffer refcounts must be zero!
+ */
+static void iocache_invalidate_range(struct iocache_private_data *data,
+				     blk64_t block, uint64_t count)
+{
+	LIST_HEAD(list);
+	uint64_t i;
+
+	for (i = 0; i < count; i++) {
+		struct iocache_key ukey = {
+			.block = block + i,
+		};
+		struct cache_node *node;
+
+		cache_node_get(&data->cache, &ukey, CACHE_GET_INCORE,
+			       &node);
+		if (node) {
+			iocache_add_list(&data->cache, node, &list);
+			cache_node_put(&data->cache, node);
+		}
+	}
+	iocache_invalidate_bufs(data, &list);
+}
+
+static const struct cache_operations iocache_ops = {
+	.hash		= iocache_hash,
+	.alloc		= iocache_alloc_node,
+	.flush		= iocache_flush_node,
+	.relse		= iocache_relse,
+	.compare	= iocache_compare,
+	.bulkrelse	= iocache_bulkrelse,
+	.resize		= cache_gradual_resize,
+};
+
 static errcode_t iocache_open(const char *name, int flags, io_channel *channel)
 {
 	io_channel	io = NULL;
@@ -65,6 +307,9 @@ static errcode_t iocache_open(const char *name, int flags, io_channel *channel)
 	if (retval)
 		return retval;
 
+	/* disable any static cache in the lower io manager */
+	real->manager->set_option(real, "cache", "off");
+
 	retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
 	if (retval)
 		goto out_backing;
@@ -76,12 +321,19 @@ static errcode_t iocache_open(const char *name, int flags, io_channel *channel)
 		goto out_channel;
 	memset(data, 0, sizeof(struct iocache_private_data));
 	data->magic = IOCACHE_IO_CHANNEL_MAGIC;
+	data->io_stats.num_fields = 4;
+	data->channel = io;
 
 	io->manager = iocache_io_manager;
 	retval = ext2fs_get_mem(strlen(name) + 1, &io->name);
 	if (retval)
 		goto out_data;
 
+	retval = cache_init(CACHE_CAN_SHRINK, 1U << 10, &iocache_ops,
+			    &data->cache);
+	if (retval)
+		goto out_name;
+
 	strcpy(io->name, name);
 	io->private_data = data;
 	io->block_size = real->block_size;
@@ -91,12 +343,14 @@ static errcode_t iocache_open(const char *name, int flags, io_channel *channel)
 	io->flags = real->flags;
 	data->real = real;
 	real->app_data = io;
-	real->read_error = iocache_read_error;
-	real->write_error = iocache_write_error;
+
+	pthread_mutex_init(&data->stats_lock, NULL);
 
 	*channel = io;
 	return 0;
 
+out_name:
+	ext2fs_free_mem(&io->name);
 out_data:
 	ext2fs_free_mem(&data);
 out_channel:
@@ -116,6 +370,10 @@ static errcode_t iocache_close(io_channel channel)
 
 	if (--channel->refcount > 0)
 		return 0;
+	pthread_mutex_destroy(&data->stats_lock);
+	cache_flush(&data->cache);
+	cache_purge(&data->cache);
+	cache_destroy(&data->cache);
 	if (data->real)
 		retval = io_channel_close(data->real);
 	ext2fs_free_mem(&channel->private_data);
@@ -134,6 +392,11 @@ static errcode_t iocache_set_blksize(io_channel channel, int blksize)
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
+	retval = iocache_flush_cache(data);
+	if (retval)
+		return retval;
+	iocache_invalidate_cache(data);
+
 	retval = io_channel_set_blksize(data->real, blksize);
 	if (retval)
 		return retval;
@@ -145,21 +408,34 @@ static errcode_t iocache_set_blksize(io_channel channel, int blksize)
 static errcode_t iocache_flush(io_channel channel)
 {
 	struct iocache_private_data *data = IOCACHE(channel);
+	errcode_t retval = 0;
+	errcode_t retval2;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
-	return io_channel_flush(data->real);
+	retval = iocache_flush_cache(data);
+	retval2 = io_channel_flush(data->real);
+	if (retval)
+		return retval;
+	return retval2;
 }
 
 static errcode_t iocache_write_byte(io_channel channel, unsigned long offset,
 				    int count, const void *buf)
 {
 	struct iocache_private_data *data = IOCACHE(channel);
+	blk64_t bno = B_TO_FSBT(channel, offset);
+	blk64_t next_bno = B_TO_FSB(channel, offset + count);
+	errcode_t retval;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
+	retval = iocache_flush_range(data, bno, next_bno - bno);
+	if (retval)
+		return retval;
+	iocache_invalidate_range(data, bno, next_bno - bno);
 	return io_channel_write_byte(data->real, offset, count, buf);
 }
 
@@ -170,6 +446,16 @@ static errcode_t iocache_set_option(io_channel channel, const char *option,
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
+	errcode_t retval;
+
+	/* don't let unix io cache options leak through */
+	if (!strcmp(option, "cache_blocks") || !strcmp(option, "cache"))
+		return 0;
+
+	retval = iocache_flush_cache(data);
+	if (retval)
+		return retval;
+	iocache_invalidate_cache(data);
 
 	return data->real->manager->set_option(data->real, option, arg);
 }
@@ -181,31 +467,157 @@ static errcode_t iocache_get_stats(io_channel channel, io_stats *io_stats)
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
-	return data->real->manager->get_stats(data->real, io_stats);
+	/*
+	 * Yes, io_stats is a double-pointer, and we let the caller scribble on
+	 * our stats struct WITHOUT LOCKING!
+	 */
+	if (io_stats)
+		*io_stats = &data->io_stats;
+	return 0;
+}
+
+static void iocache_update_stats(struct iocache_private_data *data,
+				 unsigned long long bytes_read,
+				 unsigned long long bytes_written,
+				 int cache_op)
+{
+	pthread_mutex_lock(&data->stats_lock);
+	data->io_stats.bytes_read += bytes_read;
+	data->io_stats.bytes_written += bytes_written;
+	if (cache_op == CACHE_HIT)
+		data->io_stats.cache_hits++;
+	else
+		data->io_stats.cache_misses++;
+	pthread_mutex_unlock(&data->stats_lock);
 }
 
 static errcode_t iocache_read_blk64(io_channel channel,
 				    unsigned long long block, int count,
 				    void *buf)
 {
+	struct iocache_key ukey = {
+		.block = block,
+	};
 	struct iocache_private_data *data = IOCACHE(channel);
+	unsigned long long i;
+	errcode_t retval;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
-	return io_channel_read_blk64(data->real, block, count, buf);
+	/*
+	 * If we're doing an odd-sized read, flush out the cache and then do a
+	 * direct read.
+	 */
+	if (count < 0) {
+		uint64_t fsbcount = B_TO_FSB(channel, -count);
+
+		retval = iocache_flush_range(data, block, fsbcount);
+		if (retval)
+			return retval;
+		iocache_invalidate_range(data, block, fsbcount);
+		iocache_update_stats(data, 0, 0, CACHE_MISS);
+		return io_channel_read_blk64(data->real, block, count, buf);
+	}
+
+	for (i = 0; i < count; i++, ukey.block++, buf += channel->block_size) {
+		struct cache_node *node;
+		struct iocache_buf *ubuf;
+
+		cache_node_get(&data->cache, &ukey, 0, &node);
+		if (!node) {
+			/* cannot instantiate cache, just do a direct read */
+			retval = io_channel_read_blk64(data->real, ukey.block,
+						       1, buf);
+			if (retval)
+				return retval;
+			iocache_update_stats(data, channel->block_size, 0,
+					     CACHE_MISS);
+			continue;
+		}
+
+		ubuf = IOBUF(node);
+		iocache_buf_lock(ubuf);
+		if (!ubuf->uptodate) {
+			retval = io_channel_read_blk64(data->real, ukey.block,
+						       1, ubuf->buf);
+			if (!retval) {
+				ubuf->uptodate = 1;
+				iocache_update_stats(data, channel->block_size,
+						     0, CACHE_MISS);
+			}
+		} else {
+			iocache_update_stats(data, channel->block_size, 0,
+					     CACHE_HIT);
+		}
+		if (ubuf->uptodate)
+			memcpy(buf, ubuf->buf, channel->block_size);
+		iocache_buf_unlock(ubuf);
+		cache_node_put(&data->cache, node);
+		if (retval)
+			return retval;
+	}
+
+	return 0;
 }
 
 static errcode_t iocache_write_blk64(io_channel channel,
 				     unsigned long long block, int count,
 				     const void *buf)
 {
+	struct iocache_key ukey = {
+		.block = block,
+	};
 	struct iocache_private_data *data = IOCACHE(channel);
+	unsigned long long i;
+	errcode_t retval;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
-	return io_channel_write_blk64(data->real, block, count, buf);
+	/*
+	 * If we're doing an odd-sized write, flush out the cache and then do a
+	 * direct write.
+	 */
+	if (count < 0) {
+		uint64_t fsbcount = B_TO_FSB(channel, -count);
+
+		retval = iocache_flush_range(data, block, fsbcount);
+		if (retval)
+			return retval;
+		iocache_invalidate_range(data, block, fsbcount);
+		iocache_update_stats(data, 0, 0, CACHE_MISS);
+		return io_channel_write_blk64(data->real, block, count, buf);
+	}
+
+	for (i = 0; i < count; i++, ukey.block++, buf += channel->block_size) {
+		struct cache_node *node;
+		struct iocache_buf *ubuf;
+
+		cache_node_get(&data->cache, &ukey, 0, &node);
+		if (!node) {
+			/* cannot instantiate cache, do a direct write */
+			retval = io_channel_write_blk64(data->real, ukey.block,
+							1, buf);
+			if (retval)
+				return retval;
+			iocache_update_stats(data, 0, channel->block_size,
+					     CACHE_MISS);
+			continue;
+		}
+
+		ubuf = IOBUF(node);
+		iocache_buf_lock(ubuf);
+		memcpy(ubuf->buf, buf, channel->block_size);
+		iocache_update_stats(data, 0, channel->block_size,
+				     ubuf->uptodate ? CACHE_HIT : CACHE_MISS);
+		ubuf->dirty = 1;
+		ubuf->uptodate = 1;
+		iocache_buf_unlock(ubuf);
+		cache_node_put(&data->cache, node);
+	}
+
+	return 0;
 }
 
 static errcode_t iocache_read_blk(io_channel channel, unsigned long block,
@@ -224,11 +636,17 @@ static errcode_t iocache_discard(io_channel channel, unsigned long long block,
 				 unsigned long long count)
 {
 	struct iocache_private_data *data = IOCACHE(channel);
+	errcode_t retval;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
-	return io_channel_discard(data->real, block, count);
+	retval = io_channel_discard(data->real, block, count);
+	if (retval)
+		return retval;
+
+	iocache_invalidate_range(data, block, count);
+	return 0;
 }
 
 static errcode_t iocache_cache_readahead(io_channel channel,
@@ -247,11 +665,17 @@ static errcode_t iocache_zeroout(io_channel channel, unsigned long long block,
 				 unsigned long long count)
 {
 	struct iocache_private_data *data = IOCACHE(channel);
+	errcode_t retval;
 
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
-	return io_channel_zeroout(data->real, block, count);
+	retval = io_channel_zeroout(data->real, block, count);
+	if (retval)
+		return retval;
+
+	iocache_invalidate_range(data, block, count);
+	return 0;
 }
 
 static errcode_t iocache_get_fd(io_channel channel, int *fd)
@@ -273,6 +697,7 @@ static errcode_t iocache_invalidate_blocks(io_channel channel,
 	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 	EXT2_CHECK_MAGIC(data, IOCACHE_IO_CHANNEL_MAGIC);
 
+	iocache_invalidate_range(data, block, count);
 	return io_channel_invalidate_blocks(data->real, block, count);
 }
 

[PATCH 3/6] iocache: bump buffer mru priority every 50 accesses

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

If a buffer is hot enough to survive more than 50 access without being
reclaimed, bump its priority to the next MRU so it sticks around longer.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/support/cache.h   |    1 +
 lib/support/cache.c   |   16 ++++++++++++++++
 lib/support/iocache.c |    9 +++++++++
 3 files changed, 26 insertions(+)


diff --git a/lib/support/cache.h b/lib/support/cache.h
index f482948a3b6331..5a8e19f5d18e78 100644
--- a/lib/support/cache.h
+++ b/lib/support/cache.h
@@ -173,5 +173,6 @@ int cache_node_purge(struct cache *, cache_key_t, struct cache_node *);
 void cache_report(FILE *fp, const char *, struct cache *);
 int cache_overflowed(struct cache *);
 struct cache_node *cache_node_grab(struct cache *cache, struct cache_node *node);
+void cache_node_bump_priority(struct cache *cache, struct cache_node *node);
 
 #endif	/* __CACHE_H__ */
diff --git a/lib/support/cache.c b/lib/support/cache.c
index 7e1ddc3cc8788d..34df5cb51cd5e4 100644
--- a/lib/support/cache.c
+++ b/lib/support/cache.c
@@ -649,6 +649,22 @@ cache_node_put(
 		cache_shrink(cache);
 }
 
+/* Bump the priority of a cache node.  Caller must hold cn_mutex. */
+void
+cache_node_bump_priority(
+	struct cache		*cache,
+	struct cache_node	*node)
+{
+	int			*priop;
+
+	if (node->cn_priority == CACHE_DIRTY_PRIORITY)
+		priop = &node->cn_old_priority;
+	else
+		priop = &node->cn_priority;
+	if (*priop < CACHE_MAX_PRIORITY)
+		(*priop)++;
+}
+
 void
 cache_node_set_priority(
 	struct cache *		cache,
diff --git a/lib/support/iocache.c b/lib/support/iocache.c
index ab879e85d18f2a..92d88331bfa54d 100644
--- a/lib/support/iocache.c
+++ b/lib/support/iocache.c
@@ -56,6 +56,7 @@ struct iocache_buf {
 	blk64_t			block;
 	void			*buf;
 	errcode_t		write_error;
+	uint8_t			access;
 	unsigned int		uptodate:1;
 	unsigned int		dirty:1;
 };
@@ -552,6 +553,10 @@ static errcode_t iocache_read_blk64(io_channel channel,
 		}
 		if (ubuf->uptodate)
 			memcpy(buf, ubuf->buf, channel->block_size);
+		if (++ubuf->access > 50) {
+			cache_node_bump_priority(&data->cache, node);
+			ubuf->access = 0;
+		}
 		iocache_buf_unlock(ubuf);
 		cache_node_put(&data->cache, node);
 		if (retval)
@@ -613,6 +618,10 @@ static errcode_t iocache_write_blk64(io_channel channel,
 				     ubuf->uptodate ? CACHE_HIT : CACHE_MISS);
 		ubuf->dirty = 1;
 		ubuf->uptodate = 1;
+		if (++ubuf->access > 50) {
+			cache_node_bump_priority(&data->cache, node);
+			ubuf->access = 0;
+		}
 		iocache_buf_unlock(ubuf);
 		cache_node_put(&data->cache, node);
 	}

[PATCH 4/6] fuse2fs: enable caching IO manager

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Enable the new dynamic iocache I/O manager in the fuse server, and turn
off all the other cache control.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/Makefile.in  |    3 +-
 fuse4fs/fuse4fs.1.in |    6 ----
 fuse4fs/fuse4fs.c    |   71 +++----------------------------------------------
 misc/Makefile.in     |    4 ++-
 misc/fuse2fs.1.in    |    6 ----
 misc/fuse2fs.c       |   73 ++++----------------------------------------------
 6 files changed, 15 insertions(+), 148 deletions(-)


diff --git a/fuse4fs/Makefile.in b/fuse4fs/Makefile.in
index 9f3547c271638f..0a558da23ced81 100644
--- a/fuse4fs/Makefile.in
+++ b/fuse4fs/Makefile.in
@@ -147,7 +147,8 @@ fuse4fs.o: $(srcdir)/fuse4fs.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/ext2fsP.h \
  $(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/version.h \
  $(top_srcdir)/lib/e2p/e2p.h $(top_srcdir)/lib/support/cache.h \
- $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/support/xbitops.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/support/xbitops.h \
+ $(top_srcdir)/lib/support/iocache.h
 journal.o: $(srcdir)/../debugfs/journal.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/../debugfs/journal.h \
  $(top_srcdir)/e2fsck/jfs_user.h $(top_srcdir)/e2fsck/e2fsck.h \
diff --git a/fuse4fs/fuse4fs.1.in b/fuse4fs/fuse4fs.1.in
index 119cbcc903d8af..7ab197465c9713 100644
--- a/fuse4fs/fuse4fs.1.in
+++ b/fuse4fs/fuse4fs.1.in
@@ -48,12 +48,6 @@ .SS "fuse4fs options:"
 \fB-o\fR acl
 enable file access control lists
 .TP
-\fB-o\fR cache_size
-Set the disk cache size to this quantity.
-The quantity may contain the suffixes k, m, or g.
-By default, the size is 32MB.
-The size may not be larger than 2GB.
-.TP
 \fB-o\fR direct
 Use O_DIRECT to access the block device.
 .TP
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index c4397fc365ced7..2dd7c0f6759de5 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -53,6 +53,7 @@
 #include "ext2fs/ext2fsP.h"
 #include "support/list.h"
 #include "support/cache.h"
+#include "support/iocache.h"
 
 #include "../version.h"
 #include "uuid/uuid.h"
@@ -290,7 +291,6 @@ struct fuse4fs {
 	unsigned int blockmask;
 	unsigned long offset;
 	unsigned int next_generation;
-	unsigned long long cache_size;
 	char *lockfile;
 #ifdef HAVE_CLOCK_MONOTONIC
 	struct timespec lock_start_time;
@@ -1289,7 +1289,8 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
 
 	dbg_printf(ff, "opening with flags=0x%x\n", flags);
 
-	err = ext2fs_open2(ff->device, options, flags, 0, 0, unix_io_manager,
+	iocache_set_backing_manager(unix_io_manager);
+	err = ext2fs_open2(ff->device, options, flags, 0, 0, iocache_io_manager,
 			   &ff->fs);
 	if (err == EPERM) {
 		err_printf(ff, "%s.\n",
@@ -1298,7 +1299,7 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
 		ff->ro = 1;
 		ff->norecovery = 1;
 		err = ext2fs_open2(ff->device, options, flags, 0, 0,
-				   unix_io_manager, &ff->fs);
+				   iocache_io_manager, &ff->fs);
 	}
 	if (err) {
 		err_printf(ff, "%s.\n", error_message(err));
@@ -1321,25 +1322,6 @@ static inline bool fuse4fs_on_bdev(const struct fuse4fs *ff)
 	return ff->fs->io->flags & CHANNEL_FLAGS_BLOCK_DEVICE;
 }
 
-static errcode_t fuse4fs_config_cache(struct fuse4fs *ff)
-{
-	char buf[128];
-	errcode_t err;
-
-	snprintf(buf, sizeof(buf), "cache_blocks=%llu",
-		 FUSE4FS_B_TO_FSBT(ff, ff->cache_size));
-	err = io_channel_set_options(ff->fs->io, buf);
-	if (err) {
-		err_printf(ff, "%s %lluk: %s\n",
-			   _("cannot set disk cache size to"),
-			   ff->cache_size >> 10,
-			   error_message(err));
-		return err;
-	}
-
-	return 0;
-}
-
 static errcode_t fuse4fs_check_support(struct fuse4fs *ff)
 {
 	ext2_filsys fs = ff->fs;
@@ -7193,7 +7175,6 @@ enum {
 	FUSE4FS_VERSION,
 	FUSE4FS_HELP,
 	FUSE4FS_HELPFULL,
-	FUSE4FS_CACHE_SIZE,
 	FUSE4FS_DIRSYNC,
 	FUSE4FS_ERRORS_BEHAVIOR,
 #ifdef HAVE_FUSE_IOMAP
@@ -7243,7 +7224,6 @@ static struct fuse_opt fuse4fs_opts[] = {
 	FUSE_OPT_KEY("user_xattr",	FUSE4FS_IGNORED),
 	FUSE_OPT_KEY("noblock_validity", FUSE4FS_IGNORED),
 	FUSE_OPT_KEY("nodelalloc",	FUSE4FS_IGNORED),
-	FUSE_OPT_KEY("cache_size=%s",	FUSE4FS_CACHE_SIZE),
 	FUSE_OPT_KEY("dirsync",		FUSE4FS_DIRSYNC),
 	FUSE_OPT_KEY("errors=%s",	FUSE4FS_ERRORS_BEHAVIOR),
 #ifdef HAVE_FUSE_IOMAP
@@ -7282,16 +7262,6 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
 			return 0;
 		}
 		return 1;
-	case FUSE4FS_CACHE_SIZE:
-		ff->cache_size = parse_num_blocks2(arg + 11, -1);
-		if (ff->cache_size < 1 || ff->cache_size > INT32_MAX) {
-			fprintf(stderr, "%s: %s\n", arg,
- _("cache size must be between 1 block and 2GB."));
-			return -1;
-		}
-
-		/* do not pass through to libfuse */
-		return 0;
 	case FUSE4FS_ERRORS_BEHAVIOR:
 		if (strcmp(arg + 7, "continue") == 0)
 			ff->errors_behavior = EXT2_ERRORS_CONTINUE;
@@ -7348,7 +7318,6 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
 	"    -o kernel              run this as if it were the kernel, which sets:\n"
 	"                           allow_others,default_permissions,suid,dev\n"
 	"    -o directio            use O_DIRECT to read and write the disk\n"
-	"    -o cache_size=N[KMG]   use a disk cache of this size\n"
 	"    -o errors=             behavior when an error is encountered:\n"
 	"                           continue|remount-ro|panic\n"
 #ifdef HAVE_FUSE_IOMAP
@@ -7391,28 +7360,6 @@ static const char *get_subtype(const char *argv0)
 	return "ext4";
 }
 
-/* Figure out a reasonable default size for the disk cache */
-static unsigned long long default_cache_size(void)
-{
-	long pages = 0, pagesize = 0;
-	unsigned long long max_cache;
-	unsigned long long ret = 32ULL << 20; /* 32 MB */
-
-#ifdef _SC_PHYS_PAGES
-	pages = sysconf(_SC_PHYS_PAGES);
-#endif
-#ifdef _SC_PAGESIZE
-	pagesize = sysconf(_SC_PAGESIZE);
-#endif
-	if (pages > 0 && pagesize > 0) {
-		max_cache = (unsigned long long)pagesize * pages / 20;
-
-		if (max_cache > 0 && ret > max_cache)
-			ret = max_cache;
-	}
-	return ret;
-}
-
 #ifdef HAVE_FUSE_IOMAP
 static inline bool fuse4fs_discover_iomap(struct fuse4fs *ff)
 {
@@ -7687,16 +7634,6 @@ int main(int argc, char *argv[])
 		fctx.translate_inums = 0;
 	}
 
-	if (!fctx.cache_size)
-		fctx.cache_size = default_cache_size();
-	if (fctx.cache_size) {
-		err = fuse4fs_config_cache(&fctx);
-		if (err) {
-			ret = 32;
-			goto out;
-		}
-	}
-
 	err = fuse4fs_check_support(&fctx);
 	if (err) {
 		ret = 32;
diff --git a/misc/Makefile.in b/misc/Makefile.in
index ec964688acd623..8a3adc70fb736e 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -880,7 +880,9 @@ fuse2fs.o: $(srcdir)/fuse2fs.c $(top_builddir)/lib/config.h \
  $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
  $(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/ext2fsP.h \
  $(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/version.h \
- $(top_srcdir)/lib/e2p/e2p.h
+ $(top_srcdir)/lib/e2p/e2p.h $(top_srcdir)/lib/support/cache.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/support/xbitops.h \
+ $(top_srcdir)/lib/support/iocache.h
 e2fuzz.o: $(srcdir)/e2fuzz.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/ext2fs/ext2_fs.h \
  $(top_builddir)/lib/ext2fs/ext2_types.h $(top_srcdir)/lib/ext2fs/ext2fs.h \
diff --git a/misc/fuse2fs.1.in b/misc/fuse2fs.1.in
index 0c0934f03c9543..21917bdda31a12 100644
--- a/misc/fuse2fs.1.in
+++ b/misc/fuse2fs.1.in
@@ -48,12 +48,6 @@ .SS "fuse2fs options:"
 \fB-o\fR acl
 enable file access control lists
 .TP
-\fB-o\fR cache_size
-Set the disk cache size to this quantity.
-The quantity may contain the suffixes k, m, or g.
-By default, the size is 32MB.
-The size may not be larger than 2GB.
-.TP
 \fB-o\fR direct
 Use O_DIRECT to access the block device.
 .TP
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 5e4680ca023282..8bd7cedc9f1ca8 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -50,6 +50,9 @@
 #include "ext2fs/ext2fs.h"
 #include "ext2fs/ext2_fs.h"
 #include "ext2fs/ext2fsP.h"
+#include "support/list.h"
+#include "support/cache.h"
+#include "support/iocache.h"
 
 #include "../version.h"
 #include "uuid/uuid.h"
@@ -283,7 +286,6 @@ struct fuse2fs {
 	unsigned int blockmask;
 	unsigned long offset;
 	unsigned int next_generation;
-	unsigned long long cache_size;
 	char *lockfile;
 #ifdef HAVE_CLOCK_MONOTONIC
 	struct timespec lock_start_time;
@@ -1119,7 +1121,8 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff, int libext2_flags)
 
 	dbg_printf(ff, "opening with flags=0x%x\n", flags);
 
-	err = ext2fs_open2(ff->device, options, flags, 0, 0, unix_io_manager,
+	iocache_set_backing_manager(unix_io_manager);
+	err = ext2fs_open2(ff->device, options, flags, 0, 0, iocache_io_manager,
 			   &ff->fs);
 	if (err == EPERM) {
 		err_printf(ff, "%s.\n",
@@ -1128,7 +1131,7 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff, int libext2_flags)
 		ff->ro = 1;
 		ff->norecovery = 1;
 		err = ext2fs_open2(ff->device, options, flags, 0, 0,
-				   unix_io_manager, &ff->fs);
+				   iocache_io_manager, &ff->fs);
 	}
 	if (err) {
 		err_printf(ff, "%s.\n", error_message(err));
@@ -1147,25 +1150,6 @@ static inline bool fuse2fs_on_bdev(const struct fuse2fs *ff)
 	return ff->fs->io->flags & CHANNEL_FLAGS_BLOCK_DEVICE;
 }
 
-static errcode_t fuse2fs_config_cache(struct fuse2fs *ff)
-{
-	char buf[128];
-	errcode_t err;
-
-	snprintf(buf, sizeof(buf), "cache_blocks=%llu",
-		 FUSE2FS_B_TO_FSBT(ff, ff->cache_size));
-	err = io_channel_set_options(ff->fs->io, buf);
-	if (err) {
-		err_printf(ff, "%s %lluk: %s\n",
-			   _("cannot set disk cache size to"),
-			   ff->cache_size >> 10,
-			   error_message(err));
-		return err;
-	}
-
-	return 0;
-}
-
 static errcode_t fuse2fs_check_support(struct fuse2fs *ff)
 {
 	ext2_filsys fs = ff->fs;
@@ -6750,7 +6734,6 @@ enum {
 	FUSE2FS_VERSION,
 	FUSE2FS_HELP,
 	FUSE2FS_HELPFULL,
-	FUSE2FS_CACHE_SIZE,
 	FUSE2FS_DIRSYNC,
 	FUSE2FS_ERRORS_BEHAVIOR,
 #ifdef HAVE_FUSE_IOMAP
@@ -6800,7 +6783,6 @@ static struct fuse_opt fuse2fs_opts[] = {
 	FUSE_OPT_KEY("user_xattr",	FUSE2FS_IGNORED),
 	FUSE_OPT_KEY("noblock_validity", FUSE2FS_IGNORED),
 	FUSE_OPT_KEY("nodelalloc",	FUSE2FS_IGNORED),
-	FUSE_OPT_KEY("cache_size=%s",	FUSE2FS_CACHE_SIZE),
 	FUSE_OPT_KEY("dirsync",		FUSE2FS_DIRSYNC),
 	FUSE_OPT_KEY("errors=%s",	FUSE2FS_ERRORS_BEHAVIOR),
 #ifdef HAVE_FUSE_IOMAP
@@ -6839,16 +6821,6 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
 			return 0;
 		}
 		return 1;
-	case FUSE2FS_CACHE_SIZE:
-		ff->cache_size = parse_num_blocks2(arg + 11, -1);
-		if (ff->cache_size < 1 || ff->cache_size > INT32_MAX) {
-			fprintf(stderr, "%s: %s\n", arg,
- _("cache size must be between 1 block and 2GB."));
-			return -1;
-		}
-
-		/* do not pass through to libfuse */
-		return 0;
 	case FUSE2FS_ERRORS_BEHAVIOR:
 		if (strcmp(arg + 7, "continue") == 0)
 			ff->errors_behavior = EXT2_ERRORS_CONTINUE;
@@ -6905,7 +6877,6 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
 	"    -o kernel              run this as if it were the kernel, which sets:\n"
 	"                           allow_others,default_permissions,suid,dev\n"
 	"    -o directio            use O_DIRECT to read and write the disk\n"
-	"    -o cache_size=N[KMG]   use a disk cache of this size\n"
 	"    -o errors=             behavior when an error is encountered:\n"
 	"                           continue|remount-ro|panic\n"
 #ifdef HAVE_FUSE_IOMAP
@@ -6949,28 +6920,6 @@ static const char *get_subtype(const char *argv0)
 	return "ext4";
 }
 
-/* Figure out a reasonable default size for the disk cache */
-static unsigned long long default_cache_size(void)
-{
-	long pages = 0, pagesize = 0;
-	unsigned long long max_cache;
-	unsigned long long ret = 32ULL << 20; /* 32 MB */
-
-#ifdef _SC_PHYS_PAGES
-	pages = sysconf(_SC_PHYS_PAGES);
-#endif
-#ifdef _SC_PAGESIZE
-	pagesize = sysconf(_SC_PAGESIZE);
-#endif
-	if (pages > 0 && pagesize > 0) {
-		max_cache = (unsigned long long)pagesize * pages / 20;
-
-		if (max_cache > 0 && ret > max_cache)
-			ret = max_cache;
-	}
-	return ret;
-}
-
 #ifdef HAVE_FUSE_IOMAP
 static inline bool fuse2fs_discover_iomap(struct fuse2fs *ff)
 {
@@ -7130,16 +7079,6 @@ int main(int argc, char *argv[])
 		goto out;
 	}
 
-	if (!fctx.cache_size)
-		fctx.cache_size = default_cache_size();
-	if (fctx.cache_size) {
-		err = fuse2fs_config_cache(&fctx);
-		if (err) {
-			ret = 32;
-			goto out;
-		}
-	}
-
 	err = fuse2fs_check_support(&fctx);
 	if (err) {
 		ret = 32;

[PATCH 5/6] fuse2fs: increase inode cache size

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Increase the internal inode cache size.  Does this improve performance
any?

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |    4 ++++
 misc/fuse2fs.c    |    4 ++++
 2 files changed, 8 insertions(+)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 2dd7c0f6759de5..3e8822fac08630 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -1311,6 +1311,10 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
 	if (err)
 		return translate_error(ff->fs, 0, err);
 
+	err = ext2fs_create_inode_cache(ff->fs, 1024);
+	if (err)
+		return translate_error(ff->fs, 0, err);
+
 	ff->fs->priv_data = ff;
 	ff->blocklog = u_log2(ff->fs->blocksize);
 	ff->blockmask = ff->fs->blocksize - 1;
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 8bd7cedc9f1ca8..83a3ed3ac3450e 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1139,6 +1139,10 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff, int libext2_flags)
 		return err;
 	}
 
+	err = ext2fs_create_inode_cache(ff->fs, 1024);
+	if (err)
+		return translate_error(ff->fs, 0, err);
+
 	ff->fs->priv_data = ff;
 	ff->blocklog = u_log2(ff->fs->blocksize);
 	ff->blockmask = ff->fs->blocksize - 1;

[PATCH 6/6] libext2fs: improve caching for inodes

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Use our new cache code to improve the ondisk inode cache inside
libext2fs.  Oops, list.h duplication, and libext2fs needs to link
against libsupport now.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/ext2fsP.h    |   13 ++-
 debugfs/Makefile.in     |    4 -
 e2fsck/Makefile.in      |    4 -
 lib/ext2fs/Makefile.in  |    4 +
 lib/ext2fs/inode.c      |  215 +++++++++++++++++++++++++++++++++++++----------
 resize/Makefile.in      |    4 -
 tests/progs/Makefile.in |    4 -
 7 files changed, 187 insertions(+), 61 deletions(-)


diff --git a/lib/ext2fs/ext2fsP.h b/lib/ext2fs/ext2fsP.h
index 428081c9e2ff38..8490dd5139d543 100644
--- a/lib/ext2fs/ext2fsP.h
+++ b/lib/ext2fs/ext2fsP.h
@@ -82,21 +82,26 @@ struct dir_context {
 	errcode_t	errcode;
 };
 
+#include "support/list.h"
+#include "support/cache.h"
+
 /*
  * Inode cache structure
  */
 struct ext2_inode_cache {
 	void *				buffer;
 	blk64_t				buffer_blk;
-	int				cache_last;
-	unsigned int			cache_size;
 	int				refcount;
-	struct ext2_inode_cache_ent	*cache;
+	struct cache			cache;
 };
 
 struct ext2_inode_cache_ent {
+	struct cache_node	node;
 	ext2_ino_t		ino;
-	struct ext2_inode	*inode;
+	uint8_t			access;
+
+	/* bytes representing a host-endian ext2_inode_large object */
+	char			raw[];
 };
 
 /*
diff --git a/debugfs/Makefile.in b/debugfs/Makefile.in
index 700ae87418c268..8dfd802692b839 100644
--- a/debugfs/Makefile.in
+++ b/debugfs/Makefile.in
@@ -38,9 +38,9 @@ SRCS= debug_cmds.c $(srcdir)/debugfs.c $(srcdir)/util.c $(srcdir)/ls.c \
 	$(srcdir)/../e2fsck/recovery.c $(srcdir)/do_journal.c \
 	$(srcdir)/do_orphan.c
 
-LIBS= $(LIBSUPPORT) $(LIBEXT2FS) $(LIBE2P) $(LIBSS) $(LIBCOM_ERR) $(LIBBLKID) \
+LIBS= $(LIBEXT2FS) $(LIBSUPPORT) $(LIBE2P) $(LIBSS) $(LIBCOM_ERR) $(LIBBLKID) \
 	$(LIBUUID) $(LIBMAGIC) $(SYSLIBS) $(LIBARCHIVE)
-DEPLIBS= $(DEPLIBSUPPORT) $(LIBEXT2FS) $(LIBE2P) $(DEPLIBSS) $(DEPLIBCOM_ERR) \
+DEPLIBS= $(LIBEXT2FS) $(DEPLIBSUPPORT) $(LIBE2P) $(DEPLIBSS) $(DEPLIBCOM_ERR) \
 	$(DEPLIBBLKID) $(DEPLIBUUID)
 
 STATIC_LIBS= $(STATIC_LIBSUPPORT) $(STATIC_LIBEXT2FS) $(STATIC_LIBSS) \
diff --git a/e2fsck/Makefile.in b/e2fsck/Makefile.in
index 52fad9cbfd2b23..61451f2d9e3276 100644
--- a/e2fsck/Makefile.in
+++ b/e2fsck/Makefile.in
@@ -16,9 +16,9 @@ PROGS=		e2fsck
 MANPAGES=	e2fsck.8
 FMANPAGES=	e2fsck.conf.5
 
-LIBS= $(LIBSUPPORT) $(LIBEXT2FS) $(LIBCOM_ERR) $(LIBBLKID) $(LIBUUID) \
+LIBS= $(LIBEXT2FS) $(LIBSUPPORT) $(LIBCOM_ERR) $(LIBBLKID) $(LIBUUID) \
 	$(LIBINTL) $(LIBE2P) $(LIBMAGIC) $(SYSLIBS)
-DEPLIBS= $(DEPLIBSUPPORT) $(LIBEXT2FS) $(DEPLIBCOM_ERR) $(DEPLIBBLKID) \
+DEPLIBS= $(LIBEXT2FS) $(DEPLIBSUPPORT) $(DEPLIBCOM_ERR) $(DEPLIBBLKID) \
 	 $(DEPLIBUUID) $(DEPLIBE2P)
 
 STATIC_LIBS= $(STATIC_LIBSUPPORT) $(STATIC_LIBEXT2FS) $(STATIC_LIBCOM_ERR) \
diff --git a/lib/ext2fs/Makefile.in b/lib/ext2fs/Makefile.in
index 1d0991defff804..89254ded7c0723 100644
--- a/lib/ext2fs/Makefile.in
+++ b/lib/ext2fs/Makefile.in
@@ -976,7 +976,9 @@ inode.o: $(srcdir)/inode.c $(top_builddir)/lib/config.h \
  $(srcdir)/ext2fs.h $(srcdir)/ext2_fs.h $(srcdir)/ext3_extents.h \
  $(top_srcdir)/lib/et/com_err.h $(srcdir)/ext2_io.h \
  $(top_builddir)/lib/ext2fs/ext2_err.h $(srcdir)/ext2_ext_attr.h \
- $(srcdir)/hashmap.h $(srcdir)/bitops.h $(srcdir)/e2image.h
+ $(srcdir)/hashmap.h $(srcdir)/bitops.h $(srcdir)/e2image.h \
+ $(srcdir)/../support/cache.h $(srcdir)/../support/list.h \
+ $(srcdir)/../support/xbitops.h 
 inode_io.o: $(srcdir)/inode_io.c $(top_builddir)/lib/config.h \
  $(top_builddir)/lib/dirpaths.h $(srcdir)/ext2_fs.h \
  $(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h \
diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c
index c9389a2324be07..8ca82af1ab35d3 100644
--- a/lib/ext2fs/inode.c
+++ b/lib/ext2fs/inode.c
@@ -59,18 +59,145 @@ struct ext2_struct_inode_scan {
 	int			reserved[6];
 };
 
+struct ext2_inode_cache_key {
+	ext2_filsys		fs;
+	ext2_ino_t		ino;
+};
+
+#define ICKEY(key)	((struct ext2_inode_cache_key *)(key))
+#define ICNODE(node)	(container_of((node), struct ext2_inode_cache_ent, node))
+
+static unsigned int
+ext2_inode_cache_hash(cache_key_t key, unsigned int hashsize,
+		      unsigned int hashshift)
+{
+	uint64_t	hashval = ICKEY(key)->ino;
+	uint64_t	tmp;
+
+	tmp = hashval ^ (GOLDEN_RATIO_PRIME + hashval) / CACHE_LINE_SIZE;
+	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> hashshift);
+	return tmp % hashsize;
+}
+
+static int ext2_inode_cache_compare(struct cache_node *node, cache_key_t key)
+{
+	struct ext2_inode_cache_ent *ent = ICNODE(node);
+	struct ext2_inode_cache_key *ikey = ICKEY(key);
+
+	if (ent->ino == ikey->ino)
+		return CACHE_HIT;
+
+	return CACHE_MISS;
+}
+
+static struct cache_node *ext2_inode_cache_alloc(struct cache *c,
+						 cache_key_t key)
+{
+	struct ext2_inode_cache_key *ikey = ICKEY(key);
+	struct ext2_inode_cache_ent *ent;
+
+	ent = calloc(1, sizeof(struct ext2_inode_cache_ent) +
+			EXT2_INODE_SIZE(ikey->fs->super));
+	if (!ent)
+		return NULL;
+
+	ent->ino = ikey->ino;
+	return &ent->node;
+}
+
+static bool ext2_inode_cache_flush(struct cache *c, struct cache_node *node)
+{
+	/* can always drop inode cache */
+	return 0;
+}
+
+static void ext2_inode_cache_relse(struct cache *c, struct cache_node *node)
+{
+	struct ext2_inode_cache_ent *ent = ICNODE(node);
+
+	free(ent);
+}
+
+static unsigned int ext2_inode_cache_bulkrelse(struct cache *cache,
+					       struct list_head *list)
+{
+	struct cache_node *cn, *n;
+	int count = 0;
+
+	if (list_empty(list))
+		return 0;
+
+	list_for_each_entry_safe(cn, n, list, cn_mru) {
+		ext2_inode_cache_relse(cache, cn);
+		count++;
+	}
+
+	return count;
+}
+
+static const struct cache_operations ext2_inode_cache_ops = {
+	.hash		= ext2_inode_cache_hash,
+	.alloc		= ext2_inode_cache_alloc,
+	.flush		= ext2_inode_cache_flush,
+	.relse		= ext2_inode_cache_relse,
+	.compare	= ext2_inode_cache_compare,
+	.bulkrelse	= ext2_inode_cache_bulkrelse,
+	.resize		= cache_gradual_resize,
+};
+
+static errcode_t ext2_inode_cache_iget(ext2_filsys fs, ext2_ino_t ino,
+				       unsigned int getflags,
+				       struct ext2_inode_cache_ent **entp)
+{
+	struct ext2_inode_cache_key ikey = {
+		.fs = fs,
+		.ino = ino,
+	};
+	struct cache_node *node = NULL;
+
+	cache_node_get(&fs->icache->cache, &ikey, getflags, &node);
+	if (!node)
+		return ENOMEM;
+
+	*entp = ICNODE(node);
+	return 0;
+}
+
+static void ext2_inode_cache_iput(ext2_filsys fs,
+				  struct ext2_inode_cache_ent *ent)
+{
+	cache_node_put(&fs->icache->cache, &ent->node);
+}
+
+static int ext2_inode_cache_ipurge(ext2_filsys fs, ext2_ino_t ino,
+				   struct ext2_inode_cache_ent *ent)
+{
+	struct ext2_inode_cache_key ikey = {
+		.fs = fs,
+		.ino = ino,
+	};
+
+	return cache_node_purge(&fs->icache->cache, &ikey, &ent->node);
+}
+
+static void ext2_inode_cache_ibump(ext2_filsys fs,
+				   struct ext2_inode_cache_ent *ent)
+{
+	if (++ent->access > 50) {
+		cache_node_bump_priority(&fs->icache->cache, &ent->node);
+		ent->access = 0;
+	}
+}
+
 /*
  * This routine flushes the icache, if it exists.
  */
 errcode_t ext2fs_flush_icache(ext2_filsys fs)
 {
-	unsigned	i;
-
 	if (!fs->icache)
 		return 0;
 
-	for (i=0; i < fs->icache->cache_size; i++)
-		fs->icache->cache[i].ino = 0;
+	cache_purge(&fs->icache->cache);
 
 	fs->icache->buffer_blk = 0;
 	return 0;
@@ -81,23 +208,20 @@ errcode_t ext2fs_flush_icache(ext2_filsys fs)
  */
 void ext2fs_free_inode_cache(struct ext2_inode_cache *icache)
 {
-	unsigned i;
-
 	if (--icache->refcount)
 		return;
 	if (icache->buffer)
 		ext2fs_free_mem(&icache->buffer);
-	for (i = 0; i < icache->cache_size; i++)
-		ext2fs_free_mem(&icache->cache[i].inode);
-	if (icache->cache)
-		ext2fs_free_mem(&icache->cache);
+	if (cache_initialized(&icache->cache)) {
+		cache_purge(&icache->cache);
+		cache_destroy(&icache->cache);
+	}
 	icache->buffer_blk = 0;
 	ext2fs_free_mem(&icache);
 }
 
 errcode_t ext2fs_create_inode_cache(ext2_filsys fs, unsigned int cache_size)
 {
-	unsigned	i;
 	errcode_t	retval;
 
 	if (fs->icache)
@@ -112,22 +236,12 @@ errcode_t ext2fs_create_inode_cache(ext2_filsys fs, unsigned int cache_size)
 		goto errout;
 
 	fs->icache->buffer_blk = 0;
-	fs->icache->cache_last = -1;
-	fs->icache->cache_size = cache_size;
 	fs->icache->refcount = 1;
-	retval = ext2fs_get_array(fs->icache->cache_size,
-				  sizeof(struct ext2_inode_cache_ent),
-				  &fs->icache->cache);
+	retval = cache_init(0, cache_size, &ext2_inode_cache_ops,
+			    &fs->icache->cache);
 	if (retval)
 		goto errout;
 
-	for (i = 0; i < fs->icache->cache_size; i++) {
-		retval = ext2fs_get_mem(EXT2_INODE_SIZE(fs->super),
-					&fs->icache->cache[i].inode);
-		if (retval)
-			goto errout;
-	}
-
 	ext2fs_flush_icache(fs);
 	return 0;
 errout:
@@ -762,12 +876,12 @@ errcode_t ext2fs_read_inode2(ext2_filsys fs, ext2_ino_t ino,
 	unsigned long 	block, offset;
 	char 		*ptr;
 	errcode_t	retval;
-	unsigned	i;
 	int		clen, inodes_per_block;
 	io_channel	io;
 	int		length = EXT2_INODE_SIZE(fs->super);
 	struct ext2_inode_large	*iptr;
-	int		cache_slot, fail_csum;
+	struct ext2_inode_cache_ent *ent = NULL;
+	int		fail_csum;
 
 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 
@@ -794,12 +908,12 @@ errcode_t ext2fs_read_inode2(ext2_filsys fs, ext2_ino_t ino,
 			return retval;
 	}
 	/* Check to see if it's in the inode cache */
-	for (i = 0; i < fs->icache->cache_size; i++) {
-		if (fs->icache->cache[i].ino == ino) {
-			memcpy(inode, fs->icache->cache[i].inode,
-			       (bufsize > length) ? length : bufsize);
-			return 0;
-		}
+	ext2_inode_cache_iget(fs, ino, CACHE_GET_INCORE, &ent);
+	if (ent) {
+		memcpy(inode, ent->raw, (bufsize > length) ? length : bufsize);
+		ext2_inode_cache_ibump(fs, ent);
+		ext2_inode_cache_iput(fs, ent);
+		return 0;
 	}
 	if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
 		inodes_per_block = fs->blocksize / EXT2_INODE_SIZE(fs->super);
@@ -827,8 +941,10 @@ errcode_t ext2fs_read_inode2(ext2_filsys fs, ext2_ino_t ino,
 	}
 	offset &= (EXT2_BLOCK_SIZE(fs->super) - 1);
 
-	cache_slot = (fs->icache->cache_last + 1) % fs->icache->cache_size;
-	iptr = (struct ext2_inode_large *)fs->icache->cache[cache_slot].inode;
+	retval = ext2_inode_cache_iget(fs, ino, 0, &ent);
+	if (retval)
+		return retval;
+	iptr = (struct ext2_inode_large *)ent->raw;
 
 	ptr = (char *) iptr;
 	while (length) {
@@ -863,13 +979,15 @@ errcode_t ext2fs_read_inode2(ext2_filsys fs, ext2_ino_t ino,
 			       0, length);
 #endif
 
-	/* Update the inode cache bookkeeping */
-	if (!fail_csum) {
-		fs->icache->cache_last = cache_slot;
-		fs->icache->cache[cache_slot].ino = ino;
-	}
 	memcpy(inode, iptr, (bufsize > length) ? length : bufsize);
 
+	/* Update the inode cache bookkeeping */
+	if (!fail_csum)
+		ext2_inode_cache_ibump(fs, ent);
+	ext2_inode_cache_iput(fs, ent);
+	if (fail_csum)
+		ext2_inode_cache_ipurge(fs, ino, ent);
+
 	if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
 	    !(flags & READ_INODE_NOCSUM) && fail_csum)
 		return EXT2_ET_INODE_CSUM_INVALID;
@@ -899,8 +1017,8 @@ errcode_t ext2fs_write_inode2(ext2_filsys fs, ext2_ino_t ino,
 	unsigned long block, offset;
 	errcode_t retval = 0;
 	struct ext2_inode_large *w_inode;
+	struct ext2_inode_cache_ent *ent;
 	char *ptr;
-	unsigned i;
 	int clen;
 	int length = EXT2_INODE_SIZE(fs->super);
 
@@ -933,19 +1051,20 @@ errcode_t ext2fs_write_inode2(ext2_filsys fs, ext2_ino_t ino,
 	}
 
 	/* Check to see if the inode cache needs to be updated */
-	if (fs->icache) {
-		for (i=0; i < fs->icache->cache_size; i++) {
-			if (fs->icache->cache[i].ino == ino) {
-				memcpy(fs->icache->cache[i].inode, inode,
-				       (bufsize > length) ? length : bufsize);
-				break;
-			}
-		}
-	} else {
+	if (!fs->icache) {
 		retval = ext2fs_create_inode_cache(fs, 4);
 		if (retval)
 			goto errout;
 	}
+
+	retval = ext2_inode_cache_iget(fs, ino, 0, &ent);
+	if (retval)
+		goto errout;
+
+	memcpy(ent->raw, inode, (bufsize > length) ? length : bufsize);
+	ext2_inode_cache_ibump(fs, ent);
+	ext2_inode_cache_iput(fs, ent);
+
 	memcpy(w_inode, inode, (bufsize > length) ? length : bufsize);
 
 	if (!(fs->flags & EXT2_FLAG_RW)) {
diff --git a/resize/Makefile.in b/resize/Makefile.in
index 27f721305e052e..d03d3bfc309968 100644
--- a/resize/Makefile.in
+++ b/resize/Makefile.in
@@ -28,8 +28,8 @@ SRCS= $(srcdir)/extent.c \
 	$(srcdir)/resource_track.c \
 	$(srcdir)/sim_progress.c
 
-LIBS= $(LIBE2P) $(LIBEXT2FS) $(LIBCOM_ERR) $(LIBINTL) $(SYSLIBS)
-DEPLIBS= $(LIBE2P) $(LIBEXT2FS) $(DEPLIBCOM_ERR)
+LIBS= $(LIBE2P) $(LIBEXT2FS) $(LIBSUPPORT) $(LIBCOM_ERR) $(LIBINTL) $(SYSLIBS)
+DEPLIBS= $(LIBE2P) $(LIBEXT2FS) $(DEPLIBSUPPORT) $(DEPLIBCOM_ERR)
 
 STATIC_LIBS= $(STATIC_LIBE2P) $(STATIC_LIBEXT2FS) $(STATIC_LIBCOM_ERR) \
 	$(LIBINTL) $(SYSLIBS)
diff --git a/tests/progs/Makefile.in b/tests/progs/Makefile.in
index 1a8e9299a1c1ca..64069a52c57cd3 100644
--- a/tests/progs/Makefile.in
+++ b/tests/progs/Makefile.in
@@ -23,8 +23,8 @@ TEST_ICOUNT_OBJS=	test_icount.o test_icount_cmds.o
 SRCS=	$(srcdir)/test_icount.c \
 	$(srcdir)/test_rel.c
 
-LIBS= $(LIBEXT2FS) $(LIBSS) $(LIBCOM_ERR) $(SYSLIBS)
-DEPLIBS= $(LIBEXT2FS) $(DEPLIBSS) $(DEPLIBCOM_ERR)
+LIBS= $(LIBEXT2FS) $(LIBSUPPORT) $(LIBSS) $(LIBCOM_ERR) $(SYSLIBS)
+DEPLIBS= $(LIBEXT2FS) $(DEPLIBSUPPORT) $(DEPLIBSS) $(DEPLIBCOM_ERR)
 
 .c.o:
 	$(E) "	CC $<"

[PATCH 1/4] libext2fs: fix MMP code to work with unixfd IO manager

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

The MMP code assumes that it can (re)open() the filesystem via
fs->device_name.  However, if the Unix FD IO manager is in use the path
will be the string representation of the fd number.  This is a horrible
layering violation, but let's take the easy route and reroute the open()
call to dup() if desirable.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 lib/ext2fs/mmp.c |   46 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)


diff --git a/lib/ext2fs/mmp.c b/lib/ext2fs/mmp.c
index eb9417020e6d3f..936ae920563fc5 100644
--- a/lib/ext2fs/mmp.c
+++ b/lib/ext2fs/mmp.c
@@ -26,6 +26,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <limits.h>
 
 #include "ext2fs/ext2_fs.h"
 #include "ext2fs/ext2fs.h"
@@ -41,6 +42,49 @@
 #endif
 #endif
 
+static int ext2fs_mmp_open_device(ext2_filsys fs, int flags)
+{
+	struct stat st;
+	char *endptr = NULL;
+	long maybe_fd;
+	int new_fd;
+	int want_directio = 1;
+	int ret;
+
+	/*
+	 * If the device name is only a number, then most likely the unixfd IO
+	 * manager is in use here.  Try to extract the fd number; if we can't,
+	 * then fall back to regular open.
+	 */
+	errno = 0;
+	maybe_fd = strtol(fs->device_name, &endptr, 10);
+	if (errno || endptr != fs->device_name + strlen(fs->device_name))
+		return open(fs->device_name, flags);
+
+	if (maybe_fd < 0 || maybe_fd > INT_MAX)
+		return -1;
+
+	/* Skip directio if this is a regular file, just like below */
+	ret = fstat(maybe_fd, &st);
+	if (ret == 0 && S_ISREG(st.st_mode))
+		want_directio = 0;
+
+	/* Duplicate the fd so that the MMP code can close it later */
+	new_fd = dup(maybe_fd);
+	if (new_fd < 0)
+		return -1;
+
+	if (want_directio) {
+		ret = fcntl(new_fd, F_SETFL, O_DIRECT);
+		if (ret) {
+			close(new_fd);
+			return -1;
+		}
+	}
+
+	return new_fd;
+}
+
 errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
 {
 #ifdef CONFIG_MMP
@@ -70,7 +114,7 @@ errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
 		    S_ISREG(st.st_mode))
 			flags &= ~O_DIRECT;
 
-		fs->mmp_fd = open(fs->device_name, flags);
+		fs->mmp_fd = ext2fs_mmp_open_device(fs, flags);
 		if (fs->mmp_fd < 0) {
 			retval = EXT2_ET_MMP_OPEN_DIRECT;
 			goto out;

[PATCH 2/4] fuse4fs: enable safe service mode

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Make it possible to run fuse4fs as a safe systemd service, wherein the
fuse server only has access to the fds that we pass in.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 MCONFIG.in                  |    1 
 configure                   |  133 +++++++++++++++++++++++
 configure.ac                |   45 ++++++++
 debian/fuse4fs.install      |    2 
 fuse4fs/Makefile.in         |   40 ++++++-
 fuse4fs/fuse4fs.c           |  253 ++++++++++++++++++++++++++++++++++++++++++-
 fuse4fs/fuse4fs.socket.in   |   14 ++
 fuse4fs/fuse4fs@.service.in |   95 ++++++++++++++++
 lib/config.h.in             |    3 +
 util/subst.conf.in          |    2 
 10 files changed, 577 insertions(+), 11 deletions(-)
 create mode 100644 fuse4fs/fuse4fs.socket.in
 create mode 100644 fuse4fs/fuse4fs@.service.in


diff --git a/MCONFIG.in b/MCONFIG.in
index 96c6fe8928b1d6..7f94ebf23c2124 100644
--- a/MCONFIG.in
+++ b/MCONFIG.in
@@ -42,6 +42,7 @@ HAVE_CROND = @have_crond@
 CROND_DIR = @crond_dir@
 HAVE_SYSTEMD = @have_systemd@
 SYSTEMD_SYSTEM_UNIT_DIR = @systemd_system_unit_dir@
+HAVE_FUSE_SERVICE = @have_fuse_service@
 
 @SET_MAKE@
 
diff --git a/configure b/configure
index 4137f942efaef5..b2b8bbf2f92ea3 100755
--- a/configure
+++ b/configure
@@ -703,6 +703,8 @@ UNI_DIFF_OPTS
 SEM_INIT_LIB
 FUSE4FS_CMT
 FUSE2FS_CMT
+fuse_service_socket_dir
+have_fuse_service
 FUSE_LIB
 fuse3_LIBS
 fuse3_CFLAGS
@@ -933,6 +935,7 @@ with_libiconv_prefix
 with_libintl_prefix
 enable_largefile
 with_libarchive
+with_fuse_service_socket_dir
 enable_fuse2fs
 enable_fuse4fs
 enable_lto
@@ -1654,6 +1657,8 @@ Optional Packages:
   --with-libintl-prefix[=DIR]  search for libintl in DIR/include and DIR/lib
   --without-libintl-prefix     don't search for libintl in includedir and libdir
   --without-libarchive    disable use of libarchive
+  --with-fuse-service-socket-dir[=DIR]
+                          Create fuse3 filesystem service sockets in DIR.
   --with-multiarch=ARCH   specify the multiarch triplet
   --with-udev-rules-dir[=DIR]
                           Install udev rules into DIR.
@@ -14336,6 +14341,134 @@ printf "%s\n" "#define HAVE_FUSE_LOWLEVEL 1" >>confdefs.h
 
 fi
 
+have_fuse_service=
+fuse_service_socket_dir=
+if test -n "$have_fuse_lowlevel"
+then
+
+# Check whether --with-fuse_service_socket_dir was given.
+if test ${with_fuse_service_socket_dir+y}
+then :
+  withval=$with_fuse_service_socket_dir;
+else $as_nop
+  with_fuse_service_socket_dir=yes
+fi
+
+	if test "x${with_fuse_service_socket_dir}" != "xno"
+then :
+
+		if test "x${with_fuse_service_socket_dir}" = "xyes"
+then :
+
+
+pkg_failed=no
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse3" >&5
+printf %s "checking for fuse3... " >&6; }
+
+if test -n "$fuse3_CFLAGS"; then
+    pkg_cv_fuse3_CFLAGS="$fuse3_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"fuse3\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "fuse3") 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_fuse3_CFLAGS=`$PKG_CONFIG --cflags "fuse3" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+if test -n "$fuse3_LIBS"; then
+    pkg_cv_fuse3_LIBS="$fuse3_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"fuse3\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "fuse3") 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_fuse3_LIBS=`$PKG_CONFIG --libs "fuse3" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+
+
+
+if test $pkg_failed = yes; then
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi
+        if test $_pkg_short_errors_supported = yes; then
+                fuse3_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "fuse3" 2>&1`
+        else
+                fuse3_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "fuse3" 2>&1`
+        fi
+        # Put the nasty error message in config.log where it belongs
+        echo "$fuse3_PKG_ERRORS" >&5
+
+
+				with_fuse_service_socket_dir=""
+
+elif test $pkg_failed = untried; then
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+
+				with_fuse_service_socket_dir=""
+
+else
+        fuse3_CFLAGS=$pkg_cv_fuse3_CFLAGS
+        fuse3_LIBS=$pkg_cv_fuse3_LIBS
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; }
+
+				with_fuse_service_socket_dir="$($PKG_CONFIG --variable=service_socket_dir fuse3)"
+
+fi
+
+
+fi
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for fuse3 service socket dir" >&5
+printf %s "checking for fuse3 service socket dir... " >&6; }
+		fuse_service_socket_dir="${with_fuse_service_socket_dir}"
+		if test -n "${fuse_service_socket_dir}"
+then :
+
+			{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: ${fuse_service_socket_dir}" >&5
+printf "%s\n" "${fuse_service_socket_dir}" >&6; }
+			have_fuse_service="yes"
+
+else $as_nop
+
+			{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+			have_fuse_service="no"
+
+fi
+
+fi
+fi
+
+
+if test "$have_fuse_service" = yes
+then
+
+printf "%s\n" "#define HAVE_FUSE_SERVICE 1" >>confdefs.h
+
+fi
+
 FUSE2FS_CMT=
 # Check whether --enable-fuse2fs was given.
 if test ${enable_fuse2fs+y}
diff --git a/configure.ac b/configure.ac
index a1057c07b8c056..7d3e3d86fff94e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1455,6 +1455,51 @@ then
 		  [Define to 1 if fuse supports lowlevel API])
 fi
 
+dnl
+dnl Check if the FUSE library tells us where to put fs service sockets
+dnl
+have_fuse_service=
+fuse_service_socket_dir=
+if test -n "$have_fuse_lowlevel"
+then
+	AC_ARG_WITH([fuse_service_socket_dir],
+	  [AS_HELP_STRING([--with-fuse-service-socket-dir@<:@=DIR@:>@],
+		  [Create fuse3 filesystem service sockets in DIR.])],
+	  [],
+	  [with_fuse_service_socket_dir=yes])
+	AS_IF([test "x${with_fuse_service_socket_dir}" != "xno"],
+	  [
+		AS_IF([test "x${with_fuse_service_socket_dir}" = "xyes"],
+		  [
+			PKG_CHECK_MODULES([fuse3], [fuse3],
+			  [
+				with_fuse_service_socket_dir="$($PKG_CONFIG --variable=service_socket_dir fuse3)"
+			  ], [
+				with_fuse_service_socket_dir=""
+			  ])
+			m4_pattern_allow([^PKG_(MAJOR|MINOR|BUILD|REVISION)$])
+		  ])
+		AC_MSG_CHECKING([for fuse3 service socket dir])
+		fuse_service_socket_dir="${with_fuse_service_socket_dir}"
+		AS_IF([test -n "${fuse_service_socket_dir}"],
+		  [
+			AC_MSG_RESULT(${fuse_service_socket_dir})
+			have_fuse_service="yes"
+		  ],
+		  [
+			AC_MSG_RESULT(no)
+			have_fuse_service="no"
+		  ])
+	  ],
+	  [])
+fi
+AC_SUBST(have_fuse_service)
+AC_SUBST(fuse_service_socket_dir)
+if test "$have_fuse_service" = yes
+then
+	AC_DEFINE(HAVE_FUSE_SERVICE, 1, [Define to 1 if fuse supports service])
+fi
+
 dnl
 dnl Check if fuse2fs is actually built.
 dnl
diff --git a/debian/fuse4fs.install b/debian/fuse4fs.install
index fb8c8ab671c73c..2da71546e8c1d5 100644
--- a/debian/fuse4fs.install
+++ b/debian/fuse4fs.install
@@ -1,2 +1,4 @@
 /usr/bin/fuse4fs
 /usr/share/man/man1/fuse4fs.1
+[linux-any] lib/systemd/system/fuse4fs.socket
+[linux-any] lib/systemd/system/fuse4fs@.service
diff --git a/fuse4fs/Makefile.in b/fuse4fs/Makefile.in
index 0a558da23ced81..ef15316eff59ca 100644
--- a/fuse4fs/Makefile.in
+++ b/fuse4fs/Makefile.in
@@ -17,6 +17,13 @@ UMANPAGES=
 @FUSE4FS_CMT@UPROGS+=fuse4fs
 @FUSE4FS_CMT@UMANPAGES+=fuse4fs.1
 
+ifeq ($(HAVE_SYSTEMD),yes)
+SERVICE_FILES	+= fuse4fs.socket fuse4fs@.service
+INSTALLDIRS_TGT	+= installdirs-systemd
+INSTALL_TGT	+= install-systemd
+UNINSTALL_TGT	+= uninstall-systemd
+endif
+
 FUSE4FS_OBJS=	fuse4fs.o journal.o recovery.o revoke.o
 
 PROFILED_FUSE4FS_OJBS=	profiled/fuse4fs.o profiled/journal.o \
@@ -54,7 +61,7 @@ DEPEND_CFLAGS = -I$(top_srcdir)/e2fsck
 @PROFILE_CMT@	$(Q) $(CC) $(ALL_CFLAGS) -g -pg -o profiled/$*.o -c $<
 
 all:: profiled $(SPROGS) $(UPROGS) $(USPROGS) $(SMANPAGES) $(UMANPAGES) \
-	$(FMANPAGES) $(LPROGS)
+	$(FMANPAGES) $(LPROGS) $(SERVICE_FILES)
 
 all-static::
 
@@ -71,6 +78,14 @@ fuse4fs: $(FUSE4FS_OBJS) $(DEPLIBS) $(DEPLIBBLKID) $(DEPLIBUUID) \
 		$(LIBFUSE) $(LIBBLKID) $(LIBUUID) $(LIBEXT2FS) $(LIBINTL) \
 		$(CLOCK_GETTIME_LIB) $(SYSLIBS) $(LIBS_E2P)
 
+%.socket: %.socket.in $(DEP_SUBSTITUTE)
+	$(E) "	SUBST $@"
+	$(Q) $(SUBSTITUTE_UPTIME) $< $@
+
+%.service: %.service.in $(DEP_SUBSTITUTE)
+	$(E) "	SUBST $@"
+	$(Q) $(SUBSTITUTE_UPTIME) $< $@
+
 journal.o: $(srcdir)/../debugfs/journal.c
 	$(E) "	CC $<"
 	$(Q) $(CC) -c $(JOURNAL_CFLAGS) -I$(srcdir) \
@@ -93,11 +108,15 @@ fuse4fs.1: $(DEP_SUBSTITUTE) $(srcdir)/fuse4fs.1.in
 	$(E) "	SUBST $@"
 	$(Q) $(SUBSTITUTE_UPTIME) $(srcdir)/fuse4fs.1.in fuse4fs.1
 
-installdirs:
+installdirs: $(INSTALLDIRS_TGT)
 	$(E) "	MKDIR_P $(bindir) $(man1dir)"
 	$(Q) $(MKDIR_P) $(DESTDIR)$(bindir) $(DESTDIR)$(man1dir)
 
-install: all $(UMANPAGES) installdirs
+installdirs-systemd:
+	$(E) "	MKDIR_P $(SYSTEMD_SYSTEM_UNIT_DIR)"
+	$(Q) $(MKDIR_P) $(DESTDIR)$(SYSTEMD_SYSTEM_UNIT_DIR)
+
+install: all $(UMANPAGES) installdirs $(INSTALL_TGT)
 	$(Q) for i in $(UPROGS); do \
 		$(ES) "	INSTALL $(bindir)/$$i"; \
 		$(INSTALL_PROGRAM) $$i $(DESTDIR)$(bindir)/$$i; \
@@ -110,13 +129,19 @@ install: all $(UMANPAGES) installdirs
 		$(INSTALL_DATA) $$i $(DESTDIR)$(man1dir)/$$i; \
 	done
 
+install-systemd: $(SERVICE_FILES) installdirs-systemd
+	$(Q) for i in $(SERVICE_FILES); do \
+		$(ES) "	INSTALL_DATA $(SYSTEMD_SYSTEM_UNIT_DIR)/$$i"; \
+		$(INSTALL_DATA) $$i $(DESTDIR)$(SYSTEMD_SYSTEM_UNIT_DIR)/$$i; \
+	done
+
 install-strip: install
 	$(Q) for i in $(UPROGS); do \
 		$(E) "	STRIP $(bindir)/$$i"; \
 		$(STRIP) $(DESTDIR)$(bindir)/$$i; \
 	done
 
-uninstall:
+uninstall: $(UNINSTALL_TGT)
 	for i in $(UPROGS); do \
 		$(RM) -f $(DESTDIR)$(bindir)/$$i; \
 	done
@@ -124,9 +149,16 @@ uninstall:
 		$(RM) -f $(DESTDIR)$(man1dir)/$$i; \
 	done
 
+uninstall-systemd:
+	for i in $(SERVICE_FILES); do \
+		$(RM) -f $(DESTDIR)$(SYSTEMD_SYSTEM_UNIT_DIR)/$$i; \
+	done
+
 clean::
 	$(RM) -f $(UPROGS) $(UMANPAGES) profile.h \
 		fuse4fs.profiled \
+		$(SERVICE_FILES) \
+		fuse4fs.socket \
 		profiled/*.o \#* *.s *.o *.a *~ core gmon.out
 
 mostlyclean: clean
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 3e8822fac08630..db86a749b74af0 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -44,6 +44,10 @@
 # define _FILE_OFFSET_BITS 64
 #endif /* _FILE_OFFSET_BITS */
 #include <fuse_lowlevel.h>
+#ifdef HAVE_FUSE_SERVICE
+# include <sys/mount.h>
+# include <fuse_service.h>
+#endif
 #ifdef __SET_FOB_FOR_FUSE
 # undef _FILE_OFFSET_BITS
 #endif /* __SET_FOB_FOR_FUSE */
@@ -301,6 +305,11 @@ struct fuse4fs {
 #endif
 	struct fuse_session *fuse;
 	struct cache inodes;
+#ifdef HAVE_FUSE_SERVICE
+	struct fuse_service *service;
+	int bdev_fd;
+	int fusedev_fd;
+#endif
 };
 
 #define FUSE4FS_CHECK_HANDLE(req, fh) \
@@ -1196,6 +1205,167 @@ static int fuse4fs_inum_access(struct fuse4fs *ff, const struct fuse_ctx *ctxt,
 	return -EACCES;
 }
 
+#ifdef HAVE_FUSE_SERVICE
+static inline bool fuse4fs_is_service(const struct fuse4fs *ff)
+{
+	return fuse_service_accepted(ff->service);
+}
+
+static int fuse4fs_service_connect(struct fuse4fs *ff, struct fuse_args *args)
+{
+	int ret;
+
+	ret = fuse_service_accept(&ff->service);
+	if (ret)
+		return ret;
+
+	if (fuse4fs_is_service(ff))
+		fuse_service_append_args(ff->service, args);
+
+	return 0;
+}
+
+static inline int
+fuse4fs_service_parse_cmdline(struct fuse_args *args,
+			      struct fuse_cmdline_opts *opts)
+{
+	return fuse_service_parse_cmdline_opts(args, opts);
+}
+
+static void fuse4fs_service_release(struct fuse4fs *ff, int mount_ret)
+{
+	if (fuse4fs_is_service(ff)) {
+		fuse_service_send_goodbye(ff->service, mount_ret);
+		fuse_service_release(ff->service);
+	}
+}
+
+static int fuse4fs_service_finish(struct fuse4fs *ff, int ret)
+{
+	if (!fuse4fs_is_service(ff))
+		return ret;
+
+	fuse_service_destroy(&ff->service);
+
+	/*
+	 * If we're being run as a service, the return code must fit the LSB
+	 * init script action error guidelines, which is to say that we
+	 * compress all errors to 1 ("generic or unspecified error", LSB 5.0
+	 * section 22.2) and hope the admin will scan the log for what actually
+	 * happened.
+	 *
+	 * We have to sleep 2 seconds here because journald uses the pid to
+	 * connect our log messages to the systemd service.  This is critical
+	 * for capturing all the log messages if the scrub fails, because the
+	 * fail service uses the service name to gather log messages for the
+	 * error report.
+	 */
+	sleep(2);
+	if (ret != EXIT_SUCCESS)
+		return EXIT_FAILURE;
+	return EXIT_SUCCESS;
+}
+
+static int fuse4fs_service_get_config(struct fuse4fs *ff)
+{
+	int open_flags = O_RDWR | O_EXCL;
+	int ret;
+
+retry:
+	ret = fuse_service_request_file(ff->service, ff->device, open_flags,
+					0);
+	if (ret)
+		return ret;
+
+	ret = fuse_service_receive_file(ff->service, ff->device, &ff->bdev_fd);
+	if (ret == -2) {
+		if (errno == EACCES && (open_flags & O_ACCMODE) != O_RDONLY) {
+			open_flags = O_RDONLY | O_EXCL;
+			goto retry;
+		}
+		err_printf(ff, "opening %s: %s.\n", ff->device, strerror(errno));
+		return ret;
+	}
+	if (ret)
+		return ret;
+
+	if (ff->bdev_fd < 0) {
+		err_printf(ff, "%s: %s: %s.\n", ff->device,
+			   _("opening service"), strerror(-ff->bdev_fd));
+		return -1;
+	}
+
+	ret = fuse_service_finish_file_requests(ff->service);
+	if (ret)
+		return ret;
+
+	ff->fusedev_fd = fuse_service_take_fusedev(ff->service);
+	return 0;
+}
+
+static errcode_t fuse4fs_service_openfs(struct fuse4fs *ff, char *options,
+					int flags)
+{
+	char path[32];
+
+	snprintf(path, sizeof(path), "%d", ff->bdev_fd);
+	iocache_set_backing_manager(unixfd_io_manager);
+	return ext2fs_open2(path, options, flags, 0, 0, iocache_io_manager,
+			&ff->fs);
+}
+
+static int fuse4fs_service_configure_iomap(struct fuse4fs *ff)
+{
+	int error = 0;
+	int ret;
+
+	ret = fuse_service_configure_iomap(ff->service,
+					   ff->iomap_want == FT_ENABLE,
+					   &error);
+	if (ret)
+		return -1;
+
+	if (error) {
+		err_printf(ff, "%s: %s.\n", _("enabling iomap"),
+			   strerror(error));
+		return -1;
+	}
+
+	return 0;
+}
+
+static int fuse4fs_service(struct fuse4fs *ff, struct fuse_session *se,
+			   const char *mountpoint)
+{
+	char path[32];
+	int ret = 0;
+
+	snprintf(path, sizeof(path), "/dev/fd/%d", ff->fusedev_fd);
+	ret = fuse_session_mount(se, path);
+	if (ret)
+		return ret;
+
+	ret = fuse_service_mount(ff->service, se, mountpoint);
+	if (ret) {
+		err_printf(ff, "%s: %s\n", _("mounting filesystem"),
+			   strerror(errno));
+		return ret;
+	}
+
+	return 0;
+}
+#else
+# define fuse4fs_is_service(...)		(false)
+# define fuse4fs_service_connect(...)		(0)
+# define fuse4fs_service_parse_cmdline(...)	(EOPNOTSUPP)
+# define fuse4fs_service_release(...)		((void)0)
+# define fuse4fs_service_finish(ret)		(ret)
+# define fuse4fs_service_get_config(...)	(EOPNOTSUPP)
+# define fuse4fs_service_openfs(...)		(EOPNOTSUPP)
+# define fuse4fs_service_configure_iomap(...)	(EOPNOTSUPP)
+# define fuse4fs_service(...)			(EOPNOTSUPP)
+#endif
+
 static errcode_t fuse4fs_acquire_lockfile(struct fuse4fs *ff)
 {
 	char *resolved;
@@ -1290,16 +1460,22 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
 	dbg_printf(ff, "opening with flags=0x%x\n", flags);
 
 	iocache_set_backing_manager(unix_io_manager);
-	err = ext2fs_open2(ff->device, options, flags, 0, 0, iocache_io_manager,
-			   &ff->fs);
+	if (fuse4fs_is_service(ff))
+		err = fuse4fs_service_openfs(ff, options, flags);
+	else
+		err = ext2fs_open2(ff->device, options, flags, 0, 0,
+				   iocache_io_manager, &ff->fs);
 	if (err == EPERM) {
 		err_printf(ff, "%s.\n",
 			   _("read-only device, trying to mount norecovery"));
 		flags &= ~EXT2_FLAG_RW;
 		ff->ro = 1;
 		ff->norecovery = 1;
-		err = ext2fs_open2(ff->device, options, flags, 0, 0,
-				   iocache_io_manager, &ff->fs);
+		if (fuse4fs_is_service(ff))
+			err = fuse4fs_service_openfs(ff, options, flags);
+		else
+			err = ext2fs_open2(ff->device, options, flags, 0, 0,
+					   iocache_io_manager, &ff->fs);
 	}
 	if (err) {
 		err_printf(ff, "%s.\n", error_message(err));
@@ -1599,6 +1775,10 @@ static int fuse4fs_setup_logging(struct fuse4fs *ff)
 	if (logfile)
 		return fuse4fs_capture_output(ff, logfile);
 
+	/* systemd already hooked us up to /dev/ttyprintk */
+	if (fuse4fs_is_service(ff))
+		return 0;
+
 	/* in kernel mode, try to log errors to the kernel log */
 	if (ff->kernel)
 		fuse4fs_capture_output(ff, "/dev/ttyprintk");
@@ -7370,7 +7550,11 @@ static inline bool fuse4fs_discover_iomap(struct fuse4fs *ff)
 	if (ff->iomap_want == FT_DISABLE)
 		return false;
 
+#ifdef HAVE_FUSE_SERVICE
+	ff->iomap_cap = fuse_lowlevel_discover_iomap(ff->fusedev_fd);
+#else
 	ff->iomap_cap = fuse_lowlevel_discover_iomap(-1);
+#endif
 	return ff->iomap_cap & FUSE_IOMAP_SUPPORT_FILEIO;
 }
 #else
@@ -7408,7 +7592,11 @@ static int fuse4fs_main(struct fuse_args *args, struct fuse4fs *ff)
 	struct fuse_loop_config *loop_config = NULL;
 	int ret;
 
-	if (fuse_parse_cmdline(args, &opts) != 0) {
+	if (fuse4fs_is_service(ff))
+		ret = fuse4fs_service_parse_cmdline(args, &opts);
+	else
+		ret = fuse_parse_cmdline(args, &opts);
+	if (ret != 0) {
 		ret = 1;
 		goto out;
 	}
@@ -7441,7 +7629,18 @@ static int fuse4fs_main(struct fuse_args *args, struct fuse4fs *ff)
 	}
 	ff->fuse = se;
 
-	if (fuse_session_mount(se, opts.mountpoint) != 0) {
+	if (fuse4fs_is_service(ff)) {
+		/*
+		 * foreground mode is needed so that systemd actually tracks
+		 * the service correctly and doesnt try to kill it; and so that
+		 * stdout/stderr don't get zapped
+		 */
+		opts.foreground = 1;
+		ret = fuse4fs_service(ff, se, opts.mountpoint);
+	} else {
+		ret = fuse_session_mount(se, opts.mountpoint);
+	}
+	if (ret != 0) {
 		ret = 4;
 		goto out_destroy_session;
 	}
@@ -7482,6 +7681,8 @@ static int fuse4fs_main(struct fuse_args *args, struct fuse4fs *ff)
 	fuse_loop_cfg_set_idle_threads(loop_config, opts.max_idle_threads);
 	fuse_loop_cfg_set_max_threads(loop_config, 4);
 
+	fuse4fs_service_release(ff, 0);
+
 	if (fuse_session_loop_mt(se, loop_config) != 0) {
 		ret = 8;
 		goto out_loopcfg;
@@ -7499,6 +7700,7 @@ static int fuse4fs_main(struct fuse_args *args, struct fuse4fs *ff)
 out_free_opts:
 	free(opts.mountpoint);
 out:
+	fuse4fs_service_release(ff, ret);
 	return ret;
 }
 
@@ -7517,6 +7719,10 @@ int main(int argc, char *argv[])
 #endif
 		.translate_inums = 1,
 		.write_gdt_on_destroy = 1,
+#ifdef HAVE_FUSE_SERVICE
+		.bdev_fd = -1,
+		.fusedev_fd = -1,
+#endif
 	};
 	errcode_t err;
 	FILE *orig_stderr = stderr;
@@ -7524,6 +7730,22 @@ int main(int argc, char *argv[])
 	bool iomap_detected = false;
 	int ret;
 
+	/* XXX */
+	if (getenv("FUSE4FS_DEBUGGER")) {
+		char *moo = getenv("FUSE4FS_DEBUGGER");
+		int del = atoi(moo);
+
+		fprintf(stderr, "WAITING %ds FOR DEBUGGER\n", del);
+		fflush(stderr);
+		sleep(del);
+	}
+
+	ret = fuse4fs_service_connect(&fctx, &args);
+	if (ret) {
+		fprintf(stderr, "Could not connect to service socket!\n");
+		exit(1);
+	}
+
 	ret = fuse_opt_parse(&args, &fctx, fuse4fs_opts, fuse4fs_opt_proc);
 	if (ret)
 		exit(1);
@@ -7565,6 +7787,22 @@ int main(int argc, char *argv[])
 		goto out;
 	}
 
+	if (fuse4fs_is_service(&fctx)) {
+		ret = fuse4fs_service_get_config(&fctx);
+		if (ret) {
+			ret = 2;
+			goto out;
+		}
+
+		if (fctx.iomap_want != FT_DISABLE) {
+			ret = fuse4fs_service_configure_iomap(&fctx);
+			if (ret) {
+				ret = 2;
+				goto out;
+			}
+		}
+	}
+
 #ifdef HAVE_PR_SET_IO_FLUSHER
 	/*
 	 * Register as a filesystem I/O server process so that our memory
@@ -7668,7 +7906,7 @@ int main(int argc, char *argv[])
 
 	/* Set up default fuse parameters */
 	snprintf(extra_args, BUFSIZ, "-osubtype=%s,fsname=%s",
-		 get_subtype(argv[0]),
+		 get_subtype(args.argv[0]),
 		 fctx.device);
 	if (fctx.no_default_opts == 0)
 		fuse_opt_add_arg(&args, extra_args);
@@ -7748,6 +7986,7 @@ int main(int argc, char *argv[])
 	err_shortdev = NULL;
 	if (fctx.device)
 		free(fctx.device);
+	ret = fuse4fs_service_finish(&fctx, ret);
 	fuse_opt_free_args(&args);
 	return ret;
 }
diff --git a/fuse4fs/fuse4fs.socket.in b/fuse4fs/fuse4fs.socket.in
new file mode 100644
index 00000000000000..58b9173c0bd727
--- /dev/null
+++ b/fuse4fs/fuse4fs.socket.in
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Copyright (C) 2025 Oracle.  All Rights Reserved.
+# Author: Darrick J. Wong <djwong@kernel.org>
+[Unit]
+Description=Socket for ext4 Service
+
+[Socket]
+ListenSequentialPacket=@fuse_service_socket_dir@/ext2
+ListenSequentialPacket=@fuse_service_socket_dir@/ext3
+ListenSequentialPacket=@fuse_service_socket_dir@/ext4
+Accept=yes
+SocketMode=0660
+RemoveOnStop=yes
diff --git a/fuse4fs/fuse4fs@.service.in b/fuse4fs/fuse4fs@.service.in
new file mode 100644
index 00000000000000..4765df462c6461
--- /dev/null
+++ b/fuse4fs/fuse4fs@.service.in
@@ -0,0 +1,95 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Copyright (C) 2025 Oracle.  All Rights Reserved.
+# Author: Darrick J. Wong <djwong@kernel.org>
+[Unit]
+Description=ext4 Service
+
+[Service]
+Type=exec
+ExecStart=@bindir@/fuse4fs -o kernel
+
+# Try to capture core dumps
+LimitCORE=infinity
+
+SyslogIdentifier=%N
+
+# No realtime CPU scheduling
+RestrictRealtime=true
+
+# Don't let us see anything in the regular system, and don't run as root
+DynamicUser=true
+ProtectSystem=strict
+ProtectHome=true
+PrivateTmp=true
+PrivateDevices=true
+PrivateUsers=true
+
+# No network access
+PrivateNetwork=true
+ProtectHostname=true
+RestrictAddressFamilies=none
+IPAddressDeny=any
+
+# Don't let the program mess with the kernel configuration at all
+ProtectKernelLogs=true
+ProtectKernelModules=true
+ProtectKernelTunables=true
+ProtectControlGroups=true
+ProtectProc=invisible
+RestrictNamespaces=true
+RestrictFileSystems=
+
+# Hide everything in /proc, even /proc/mounts
+ProcSubset=pid
+
+# Only allow the default personality Linux
+LockPersonality=true
+
+# No writable memory pages
+MemoryDenyWriteExecute=true
+
+# Don't let our mounts leak out to the host
+PrivateMounts=true
+
+# Restrict system calls to the native arch and only enough to get things going
+SystemCallArchitectures=native
+SystemCallFilter=@system-service
+SystemCallFilter=~@privileged
+SystemCallFilter=~@resources
+
+SystemCallFilter=~@clock
+SystemCallFilter=~@cpu-emulation
+SystemCallFilter=~@debug
+SystemCallFilter=~@module
+SystemCallFilter=~@reboot
+SystemCallFilter=~@swap
+
+SystemCallFilter=~@mount
+
+# Leave a breadcrumb if we get whacked by the system call filter
+SystemCallErrorNumber=EL3RST
+
+# Log to the kernel dmesg, just like an in-kernel ext4 driver
+StandardOutput=append:/dev/ttyprintk
+StandardError=append:/dev/ttyprintk
+
+# Run with no capabilities at all
+CapabilityBoundingSet=
+AmbientCapabilities=
+NoNewPrivileges=true
+
+# fuse4fs doesn't create files
+UMask=7777
+
+# No access to hardware /dev files at all
+ProtectClock=true
+DevicePolicy=closed
+
+# Don't mess with set[ug]id anything.
+RestrictSUIDSGID=true
+
+# Don't let OOM kills of processes in this containment group kill the whole
+# service, because we don't want filesystem drivers to go down.
+OOMPolicy=continue
+OOMScoreAdjust=-1000
diff --git a/lib/config.h.in b/lib/config.h.in
index 55e515020af422..dcbbb3a7bf1ac4 100644
--- a/lib/config.h.in
+++ b/lib/config.h.in
@@ -79,6 +79,9 @@
 /* Define to 1 if fuse supports iomap */
 #undef HAVE_FUSE_IOMAP
 
+/* Define to 1 if fuse supports service */
+#undef HAVE_FUSE_SERVICE
+
 /* Define to 1 if you have the Mac OS X function
    CFLocaleCopyPreferredLanguages in the CoreFoundation framework. */
 #undef HAVE_CFLOCALECOPYPREFERREDLANGUAGES
diff --git a/util/subst.conf.in b/util/subst.conf.in
index 5af5e356d46ac7..5fc7cf8f33fa76 100644
--- a/util/subst.conf.in
+++ b/util/subst.conf.in
@@ -24,3 +24,5 @@ root_bindir		@root_bindir@
 libdir			@libdir@
 $exec_prefix		@exec_prefix@
 pkglibexecdir		@libexecdir@/e2fsprogs
+bindir			@bindir@
+fuse_service_socket_dir	@fuse_service_socket_dir@

[PATCH 3/4] fuse4fs: set proc title when in fuse service mode

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

When in fuse service mode, set the proc title so that we can identify
fuse servers by mount arguments.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 configure           |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 configure.ac        |   24 ++++++++++++++++++++++++
 fuse4fs/Makefile.in |    2 +-
 fuse4fs/fuse4fs.c   |   23 ++++++++++++++++++++++-
 lib/config.h.in     |    3 +++
 5 files changed, 98 insertions(+), 2 deletions(-)


diff --git a/configure b/configure
index b2b8bbf2f92ea3..d089e5e35a66c3 100755
--- a/configure
+++ b/configure
@@ -701,6 +701,7 @@ gcc_ranlib
 gcc_ar
 UNI_DIFF_OPTS
 SEM_INIT_LIB
+LIBBSD_LIB
 FUSE4FS_CMT
 FUSE2FS_CMT
 fuse_service_socket_dir
@@ -14599,6 +14600,53 @@ fi
 
 
 
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for setproctitle in -lbsd" >&5
+printf %s "checking for setproctitle in -lbsd... " >&6; }
+if test ${ac_cv_lib_bsd_setproctitle+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lbsd  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+char setproctitle ();
+int
+main (void)
+{
+return setproctitle ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_lib_bsd_setproctitle=yes
+else $as_nop
+  ac_cv_lib_bsd_setproctitle=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_bsd_setproctitle" >&5
+printf "%s\n" "$ac_cv_lib_bsd_setproctitle" >&6; }
+if test "x$ac_cv_lib_bsd_setproctitle" = xyes
+then :
+  LIBBSD_LIB=-lbsd
+fi
+
+
+if test "$ac_cv_lib_bsd_setproctitle" = yes ; then
+	printf "%s\n" "#define HAVE_SETPROCTITLE 1" >>confdefs.h
+
+fi
+
+
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for PR_SET_IO_FLUSHER" >&5
 printf %s "checking for PR_SET_IO_FLUSHER... " >&6; }
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
diff --git a/configure.ac b/configure.ac
index 7d3e3d86fff94e..603d6ec1a1712c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1574,6 +1574,30 @@ AS_HELP_STRING([--disable-fuse4fs],[do not build fuse4fs]),
 )
 AC_SUBST(FUSE4FS_CMT)
 
+dnl
+dnl see if setproctitle exists
+dnl
+AC_CHECK_LIB(bsd, setproctitle, [LIBBSD_LIB=-lbsd])
+AC_SUBST(LIBBSD_LIB)
+if test "$ac_cv_lib_bsd_setproctitle" = yes ; then
+	AC_DEFINE(HAVE_SETPROCTITLE, 1, Define to 1 if setproctitle])
+fi
+
+dnl AC_LINK_IFELSE(
+dnl [	AC_LANG_PROGRAM([[
+dnl #define _GNU_SOURCE
+dnl #include <bsd/unistd.h>
+dnl 	]], [[
+dnl setproctitle_init(argc, argv, environ);
+dnl setproctitle("-What sourcery is this???");
+dnl 	]])
+dnl ], have_setproctitle=yes
+dnl    AC_MSG_RESULT(yes),
+dnl    AC_MSG_RESULT(no))
+dnl if test "$setproctitle" = yes; then
+dnl   AC_DEFINE(HAVE_SETPROCTITLE, 1, [Define to 1 if setproctitle exists])
+dnl fi
+
 dnl
 dnl see if PR_SET_IO_FLUSHER exists
 dnl
diff --git a/fuse4fs/Makefile.in b/fuse4fs/Makefile.in
index ef15316eff59ca..447212f836cbc0 100644
--- a/fuse4fs/Makefile.in
+++ b/fuse4fs/Makefile.in
@@ -76,7 +76,7 @@ fuse4fs: $(FUSE4FS_OBJS) $(DEPLIBS) $(DEPLIBBLKID) $(DEPLIBUUID) \
 	$(E) "	LD $@"
 	$(Q) $(CC) $(ALL_LDFLAGS) -o fuse4fs $(FUSE4FS_OBJS) $(LIBS) \
 		$(LIBFUSE) $(LIBBLKID) $(LIBUUID) $(LIBEXT2FS) $(LIBINTL) \
-		$(CLOCK_GETTIME_LIB) $(SYSLIBS) $(LIBS_E2P)
+		$(CLOCK_GETTIME_LIB) $(SYSLIBS) $(LIBS_E2P) @LIBBSD_LIB@
 
 %.socket: %.socket.in $(DEP_SUBSTITUTE)
 	$(E) "	SUBST $@"
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index db86a749b74af0..0e43e99c3c080d 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -47,6 +47,9 @@
 #ifdef HAVE_FUSE_SERVICE
 # include <sys/mount.h>
 # include <fuse_service.h>
+# ifdef HAVE_SETPROCTITLE
+#  include <bsd/unistd.h>
+# endif
 #endif
 #ifdef __SET_FOB_FOR_FUSE
 # undef _FILE_OFFSET_BITS
@@ -1221,10 +1224,24 @@ static int fuse4fs_service_connect(struct fuse4fs *ff, struct fuse_args *args)
 
 	if (fuse4fs_is_service(ff))
 		fuse_service_append_args(ff->service, args);
-
 	return 0;
 }
 
+static void fuse4fs_service_set_proc_cmdline(struct fuse4fs *ff, int argc,
+					     char *argv[],
+					     struct fuse_args *args)
+{
+	char *cmdline;
+
+	setproctitle_init(argc, argv, environ);
+	cmdline = fuse_service_cmdline(argc, argv, args);
+	if (!cmdline)
+		return;
+
+	setproctitle("-%s", cmdline);
+	free(cmdline);
+}
+
 static inline int
 fuse4fs_service_parse_cmdline(struct fuse_args *args,
 			      struct fuse_cmdline_opts *opts)
@@ -1357,6 +1374,7 @@ static int fuse4fs_service(struct fuse4fs *ff, struct fuse_session *se,
 #else
 # define fuse4fs_is_service(...)		(false)
 # define fuse4fs_service_connect(...)		(0)
+# define fuse4fs_service_set_proc_cmdline(...)	(0)
 # define fuse4fs_service_parse_cmdline(...)	(EOPNOTSUPP)
 # define fuse4fs_service_release(...)		((void)0)
 # define fuse4fs_service_finish(ret)		(ret)
@@ -7746,6 +7764,9 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 
+	if (fuse4fs_is_service(&fctx))
+		fuse4fs_service_set_proc_cmdline(&fctx, argc, argv, &args);
+
 	ret = fuse_opt_parse(&args, &fctx, fuse4fs_opts, fuse4fs_opt_proc);
 	if (ret)
 		exit(1);
diff --git a/lib/config.h.in b/lib/config.h.in
index dcbbb3a7bf1ac4..7ef6a815213856 100644
--- a/lib/config.h.in
+++ b/lib/config.h.in
@@ -358,6 +358,9 @@
 /* Define to 1 if you have the `setmntent' function. */
 #undef HAVE_SETMNTENT
 
+/* Define to 1 if setproctitle */
+#undef HAVE_SETPROCTITLE
+
 /* Define to 1 if you have the `setresgid' function. */
 #undef HAVE_SETRESGID
 

[PATCH 4/4] fuse4fs: set iomap backing device blocksize

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

If we're running as an unprivileged iomap fuse server, we must ask the
kernel to set the blocksize of the block device.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fuse4fs/fuse4fs.c |   41 +++++++++++++++++++++++++++++++----------
 1 file changed, 31 insertions(+), 10 deletions(-)


diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 0e43e99c3c080d..40171a8cab5279 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -1371,6 +1371,21 @@ static int fuse4fs_service(struct fuse4fs *ff, struct fuse_session *se,
 
 	return 0;
 }
+
+int fuse4fs_service_set_bdev_blocksize(struct fuse4fs *ff, int dev_index)
+{
+	int ret;
+
+	ret = fuse_lowlevel_iomap_set_blocksize(ff->fusedev_fd, dev_index,
+						ff->fs->blocksize);
+	if (ret) {
+		err_printf(ff, "%s: cannot set blocksize %u: %s\n", __func__,
+			   ff->fs->blocksize, strerror(errno));
+		return -EIO;
+	}
+
+	return 0;
+}
 #else
 # define fuse4fs_is_service(...)		(false)
 # define fuse4fs_service_connect(...)		(0)
@@ -1382,6 +1397,7 @@ static int fuse4fs_service(struct fuse4fs *ff, struct fuse_session *se,
 # define fuse4fs_service_openfs(...)		(EOPNOTSUPP)
 # define fuse4fs_service_configure_iomap(...)	(EOPNOTSUPP)
 # define fuse4fs_service(...)			(EOPNOTSUPP)
+# define fuse4fs_service_set_bdev_blocksize(...) (EOPNOTSUPP)
 #endif
 
 static errcode_t fuse4fs_acquire_lockfile(struct fuse4fs *ff)
@@ -6798,21 +6814,19 @@ static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)
 {
 	errcode_t err;
 	int fd;
+	int dev_index;
 	int ret;
 
 	err = io_channel_get_fd(ff->fs->io, &fd);
 	if (err)
 		return translate_error(ff->fs, 0, err);
 
-	ret = fuse4fs_set_bdev_blocksize(ff, fd);
-	if (ret)
-		return ret;
-
-	ret = fuse_lowlevel_iomap_device_add(ff->fuse, fd, 0);
-	if (ret < 0) {
-		dbg_printf(ff, "%s: cannot register iomap dev fd=%d, err=%d\n",
-			   __func__, fd, -ret);
-		return translate_error(ff->fs, 0, -ret);
+	dev_index = fuse_lowlevel_iomap_device_add(ff->fuse, fd, 0);
+	if (dev_index < 0) {
+		ret = -dev_index;
+		dbg_printf(ff, "%s: cannot register iomap dev fd=%d: %s\n",
+			   __func__, fd, strerror(ret));
+		return translate_error(ff->fs, 0, ret);
 	}
 
 	dbg_printf(ff, "%s: registered iomap dev fd=%d iomap_dev=%u\n",
@@ -6820,7 +6834,14 @@ static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)
 
 	fuse4fs_configure_atomic_write(ff, fd);
 
-	ff->iomap_dev = ret;
+	if (fuse4fs_is_service(ff))
+		ret = fuse4fs_service_set_bdev_blocksize(ff, dev_index);
+	else
+		ret = fuse4fs_set_bdev_blocksize(ff, fd);
+	if (ret)
+		return ret;
+
+	ff->iomap_dev = dev_index;
 	return 0;
 }
 

Re: [PATCH 7/8] fuse: propagate default and file acls on creation

[Chen Linxuan]

On Tue, Sep 16, 2025 at 8:26 AM Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> For local filesystems, propagate the default and file access ACLs to new
> children when creating them, just like the other in-kernel local
> filesystems.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  fs/fuse/fuse_i.h |    4 ++
>  fs/fuse/acl.c    |   65 ++++++++++++++++++++++++++++++++++++++
>  fs/fuse/dir.c    |   92 +++++++++++++++++++++++++++++++++++++++++-------------
>  3 files changed, 138 insertions(+), 23 deletions(-)
>
>
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index 52776b77efc0e4..b9306678dcda0d 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -1507,6 +1507,10 @@ struct posix_acl *fuse_get_acl(struct mnt_idmap *idmap,
>                                struct dentry *dentry, int type);
>  int fuse_set_acl(struct mnt_idmap *, struct dentry *dentry,
>                  struct posix_acl *acl, int type);
> +int fuse_acl_create(struct inode *dir, umode_t *mode,
> +                   struct posix_acl **default_acl, struct posix_acl **acl);
> +int fuse_init_acls(struct inode *inode, const struct posix_acl *default_acl,
> +                  const struct posix_acl *acl);
>
>  /* readdir.c */
>  int fuse_readdir(struct file *file, struct dir_context *ctx);
> diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
> index 4997827ee83c6d..4faee72f1365a5 100644
> --- a/fs/fuse/acl.c
> +++ b/fs/fuse/acl.c
> @@ -203,3 +203,68 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
>
>         return ret;
>  }
> +
> +int fuse_acl_create(struct inode *dir, umode_t *mode,
> +                   struct posix_acl **default_acl, struct posix_acl **acl)
> +{
> +       struct fuse_conn *fc = get_fuse_conn(dir);
> +
> +       if (fuse_is_bad(dir))
> +               return -EIO;
> +
> +       if (IS_POSIXACL(dir) && fuse_has_local_acls(fc))
> +               return posix_acl_create(dir, mode, default_acl, acl);
> +
> +       if (!fc->dont_mask)
> +               *mode &= ~current_umask();
> +
> +       *default_acl = NULL;
> +       *acl = NULL;
> +       return 0;
> +}
> +
> +static int __fuse_set_acl(struct inode *inode, const char *name,
> +                         const struct posix_acl *acl)
> +{
> +       struct fuse_conn *fc = get_fuse_conn(inode);
> +       size_t size = posix_acl_xattr_size(acl->a_count);
> +       void *value;
> +       int ret;
> +
> +       if (size > PAGE_SIZE)
> +               return -E2BIG;
> +
> +       value = kmalloc(size, GFP_KERNEL);
> +       if (!value)
> +               return -ENOMEM;
> +
> +       ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);
> +       if (ret < 0)
> +               goto out_value;
> +
> +       ret = fuse_setxattr(inode, name, value, size, 0, 0);
> +out_value:
> +       kfree(value);
> +       return ret;
> +}
> +
> +int fuse_init_acls(struct inode *inode, const struct posix_acl *default_acl,
> +                  const struct posix_acl *acl)
> +{
> +       int ret;
> +
> +       if (default_acl) {
> +               ret = __fuse_set_acl(inode, XATTR_NAME_POSIX_ACL_DEFAULT,
> +                                    default_acl);
> +               if (ret)
> +                       return ret;
> +       }
> +
> +       if (acl) {
> +               ret = __fuse_set_acl(inode, XATTR_NAME_POSIX_ACL_ACCESS, acl);
> +               if (ret)
> +                       return ret;
> +       }
> +
> +       return 0;
> +}
> diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
> index a7f47e43692f1c..b116e42431ee12 100644
> --- a/fs/fuse/dir.c
> +++ b/fs/fuse/dir.c
> @@ -628,26 +628,28 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
>         struct fuse_entry_out outentry;
>         struct fuse_inode *fi;
>         struct fuse_file *ff;
> +       struct posix_acl *default_acl = NULL, *acl = NULL;
>         int epoch, err;
>         bool trunc = flags & O_TRUNC;
>
>         /* Userspace expects S_IFREG in create mode */
>         BUG_ON((mode & S_IFMT) != S_IFREG);
>
> +       err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> +       if (err)
> +               return err;
> +
>         epoch = atomic_read(&fm->fc->epoch);
>         forget = fuse_alloc_forget();
>         err = -ENOMEM;
>         if (!forget)
> -               goto out_err;
> +               goto out_acl_release;
>
>         err = -ENOMEM;
>         ff = fuse_file_alloc(fm, true);
>         if (!ff)
>                 goto out_put_forget_req;
>
> -       if (!fm->fc->dont_mask)
> -               mode &= ~current_umask();
> -
>         flags &= ~O_NOCTTY;
>         memset(&inarg, 0, sizeof(inarg));
>         memset(&outentry, 0, sizeof(outentry));
> @@ -699,12 +701,16 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
>                 fuse_sync_release(NULL, ff, flags);
>                 fuse_queue_forget(fm->fc, forget, outentry.nodeid, 1);
>                 err = -ENOMEM;
> -               goto out_err;
> +               goto out_acl_release;
>         }
>         kfree(forget);
>         d_instantiate(entry, inode);
>         entry->d_time = epoch;
>         fuse_change_entry_timeout(entry, &outentry);
> +
> +       err = fuse_init_acls(inode, default_acl, acl);
> +       if (err)
> +               goto out_acl_release;
>         fuse_dir_changed(dir);
>         err = generic_file_open(inode, file);
>         if (!err) {
> @@ -726,7 +732,9 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
>         fuse_file_free(ff);
>  out_put_forget_req:
>         kfree(forget);
> -out_err:
> +out_acl_release:
> +       posix_acl_release(default_acl);
> +       posix_acl_release(acl);
>         return err;
>  }
>
> @@ -785,7 +793,9 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
>   */
>  static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm,
>                                        struct fuse_args *args, struct inode *dir,
> -                                      struct dentry *entry, umode_t mode)
> +                                      struct dentry *entry, umode_t mode,
> +                                      struct posix_acl *default_acl,
> +                                      struct posix_acl *acl)
>  {
>         struct fuse_entry_out outarg;
>         struct inode *inode;
> @@ -793,14 +803,18 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
>         struct fuse_forget_link *forget;
>         int epoch, err;
>
> -       if (fuse_is_bad(dir))
> -               return ERR_PTR(-EIO);
> +       if (fuse_is_bad(dir)) {
> +               err = -EIO;
> +               goto out_acl_release;
> +       }
>
>         epoch = atomic_read(&fm->fc->epoch);
>
>         forget = fuse_alloc_forget();
> -       if (!forget)
> -               return ERR_PTR(-ENOMEM);
> +       if (!forget) {
> +               err = -ENOMEM;
> +               goto out_acl_release;
> +       }
>
>         memset(&outarg, 0, sizeof(outarg));
>         args->nodeid = get_node_id(dir);
> @@ -830,7 +844,8 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
>                           &outarg.attr, ATTR_TIMEOUT(&outarg), 0, 0);
>         if (!inode) {
>                 fuse_queue_forget(fm->fc, forget, outarg.nodeid, 1);
> -               return ERR_PTR(-ENOMEM);
> +               err = -ENOMEM;
> +               goto out_acl_release;
>         }
>         kfree(forget);
>
> @@ -846,19 +861,31 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
>                 entry->d_time = epoch;
>                 fuse_change_entry_timeout(entry, &outarg);
>         }
> +
> +       err = fuse_init_acls(inode, default_acl, acl);
> +       if (err)
> +               goto out_acl_release;
>         fuse_dir_changed(dir);
> +
> +       posix_acl_release(default_acl);
> +       posix_acl_release(acl);
>         return d;
>
>   out_put_forget_req:
>         if (err == -EEXIST)
>                 fuse_invalidate_entry(entry);
>         kfree(forget);
> + out_acl_release:
> +       posix_acl_release(default_acl);
> +       posix_acl_release(acl);
>         return ERR_PTR(err);
>  }
>
>  static int create_new_nondir(struct mnt_idmap *idmap, struct fuse_mount *fm,
>                              struct fuse_args *args, struct inode *dir,
> -                            struct dentry *entry, umode_t mode)
> +                            struct dentry *entry, umode_t mode,
> +                            struct posix_acl *default_acl,
> +                            struct posix_acl *acl)
>  {
>         /*
>          * Note that when creating anything other than a directory we
> @@ -869,7 +896,8 @@ static int create_new_nondir(struct mnt_idmap *idmap, struct fuse_mount *fm,
>          */
>         WARN_ON_ONCE(S_ISDIR(mode));
>
> -       return PTR_ERR(create_new_entry(idmap, fm, args, dir, entry, mode));
> +       return PTR_ERR(create_new_entry(idmap, fm, args, dir, entry, mode,
> +                                       default_acl, acl));
>  }
>
>  static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
> @@ -877,10 +905,13 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
>  {
>         struct fuse_mknod_in inarg;
>         struct fuse_mount *fm = get_fuse_mount(dir);
> +       struct posix_acl *default_acl, *acl;
>         FUSE_ARGS(args);
> +       int err;
>
> -       if (!fm->fc->dont_mask)
> -               mode &= ~current_umask();
> +       err = fuse_acl_create(dir, &mode, &default_acl, &acl);

Please excuse me if this is a dumb question.
In this function (including fuse_mkdir and fuse_symlink),
why can't we pair fuse_acl_create and posix_acl_release together
within the same function,
just like in fuse_create_open?

Thanks,
Chen Linxuan

> +       if (err)
> +               return err;
>
>         memset(&inarg, 0, sizeof(inarg));
>         inarg.mode = mode;
> @@ -892,7 +923,8 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
>         args.in_args[0].value = &inarg;
>         args.in_args[1].size = entry->d_name.len + 1;
>         args.in_args[1].value = entry->d_name.name;
> -       return create_new_nondir(idmap, fm, &args, dir, entry, mode);
> +       return create_new_nondir(idmap, fm, &args, dir, entry, mode,
> +                                default_acl, acl);
>  }
>
>  static int fuse_create(struct mnt_idmap *idmap, struct inode *dir,
> @@ -924,13 +956,17 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
>  {
>         struct fuse_mkdir_in inarg;
>         struct fuse_mount *fm = get_fuse_mount(dir);
> +       struct posix_acl *default_acl, *acl;
>         FUSE_ARGS(args);
> +       int err;
>
> -       if (!fm->fc->dont_mask)
> -               mode &= ~current_umask();
> +       mode |= S_IFDIR;        /* vfs doesn't set S_IFDIR for us */
> +       err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> +       if (err)
> +               return ERR_PTR(err);
>
>         memset(&inarg, 0, sizeof(inarg));
> -       inarg.mode = mode;
> +       inarg.mode = mode & ~S_IFDIR;
>         inarg.umask = current_umask();
>         args.opcode = FUSE_MKDIR;
>         args.in_numargs = 2;
> @@ -938,7 +974,8 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
>         args.in_args[0].value = &inarg;
>         args.in_args[1].size = entry->d_name.len + 1;
>         args.in_args[1].value = entry->d_name.name;
> -       return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR);
> +       return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR,
> +                               default_acl, acl);
>  }
>
>  static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
> @@ -946,7 +983,14 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
>  {
>         struct fuse_mount *fm = get_fuse_mount(dir);
>         unsigned len = strlen(link) + 1;
> +       struct posix_acl *default_acl, *acl;
> +       umode_t mode = S_IFLNK | 0777;
>         FUSE_ARGS(args);
> +       int err;
> +
> +       err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> +       if (err)
> +               return err;
>
>         args.opcode = FUSE_SYMLINK;
>         args.in_numargs = 3;
> @@ -955,7 +999,8 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
>         args.in_args[1].value = entry->d_name.name;
>         args.in_args[2].size = len;
>         args.in_args[2].value = link;
> -       return create_new_nondir(idmap, fm, &args, dir, entry, S_IFLNK);
> +       return create_new_nondir(idmap, fm, &args, dir, entry, S_IFLNK,
> +                                default_acl, acl);
>  }
>
>  void fuse_flush_time_update(struct inode *inode)
> @@ -1155,7 +1200,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir,
>         args.in_args[0].value = &inarg;
>         args.in_args[1].size = newent->d_name.len + 1;
>         args.in_args[1].value = newent->d_name.name;
> -       err = create_new_nondir(&invalid_mnt_idmap, fm, &args, newdir, newent, inode->i_mode);
> +       err = create_new_nondir(&invalid_mnt_idmap, fm, &args, newdir, newent,
> +                               inode->i_mode, NULL, NULL);
>         if (!err)
>                 fuse_update_ctime_in_cache(inode);
>         else if (err == -EINTR)
>
>
>

Re: [PATCH 1/2] iomap: trace iomap_zero_iter zeroing activities

[Christoph Hellwig]

On Mon, Sep 15, 2025 at 05:26:24PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Trace which bytes actually get zeroed.

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Can you send this out separately so that we can get it queued up ASAP?

Re: [PATCH 2/2] iomap: error out on file IO when there is no inline_data buffer

[Christoph Hellwig]

> +	if (WARN_ON_ONCE(iomap->inline_data == NULL))

Shorten this to just !iomap->inline_data instead of checking for NULL?

Same for the other two.

Otherwise this looks good, and I'd prefer to see it go upstream ASAP
instead of hiding it in your big patch pile if possible.

Re: [PATCH 1/1] libfuse: don't put HAVE_STATX in a public header

[Bernd Schubert]

On 9/16/25 02:41, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> fuse.h and fuse_lowlevel.h are public headers, don't expose internal
> build system config variables to downstream clients.  This can also lead
> to function pointer ordering issues if (say) libfuse gets built with
> HAVE_STATX but the client program doesn't define a HAVE_STATX.
> 
> Get rid of the conditionals in the public header files to fix this.

Thank you, PR with an updated commit message and removal of HAVE_STATX
from the public libfuse_config.h created here
https://github.com/libfuse/libfuse/pull/1333


Thanks,
Bernd

Re: [PATCH 7/8] fuse: propagate default and file acls on creation

[Darrick J. Wong]

On Tue, Sep 16, 2025 at 02:41:30PM +0800, Chen Linxuan wrote:
> On Tue, Sep 16, 2025 at 8:26 AM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > From: Darrick J. Wong <djwong@kernel.org>
> >
> > For local filesystems, propagate the default and file access ACLs to new
> > children when creating them, just like the other in-kernel local
> > filesystems.
> >
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  fs/fuse/fuse_i.h |    4 ++
> >  fs/fuse/acl.c    |   65 ++++++++++++++++++++++++++++++++++++++
> >  fs/fuse/dir.c    |   92 +++++++++++++++++++++++++++++++++++++++++-------------
> >  3 files changed, 138 insertions(+), 23 deletions(-)
> >
> >
<snip>
> > diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
> > index a7f47e43692f1c..b116e42431ee12 100644
> > --- a/fs/fuse/dir.c
> > +++ b/fs/fuse/dir.c
> > @@ -877,10 +905,13 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
> >  {
> >         struct fuse_mknod_in inarg;
> >         struct fuse_mount *fm = get_fuse_mount(dir);
> > +       struct posix_acl *default_acl, *acl;
> >         FUSE_ARGS(args);
> > +       int err;
> >
> > -       if (!fm->fc->dont_mask)
> > -               mode &= ~current_umask();
> > +       err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> 
> Please excuse me if this is a dumb question.
> In this function (including fuse_mkdir and fuse_symlink),
> why can't we pair fuse_acl_create and posix_acl_release together
> within the same function,
> just like in fuse_create_open?

It seemed cleaner to have create_new_{entry,nondir} consume the two acl
arguments rather than have to change every callsite:

	fuse_acl_create(...., &default_acl, &acl);

	...

	ret = create_new_nondir(..., default_acl, acl);
	posix_acl_release(default_acl);
	posix_acl_release(acl);
	return ret;

since create_new_entry is really the bottom half of mknod, mkdir,
symlink, and link.

--D

> Thanks,
> Chen Linxuan
> 
> > +       if (err)
> > +               return err;
> >
> >         memset(&inarg, 0, sizeof(inarg));
> >         inarg.mode = mode;
> > @@ -892,7 +923,8 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
> >         args.in_args[0].value = &inarg;
> >         args.in_args[1].size = entry->d_name.len + 1;
> >         args.in_args[1].value = entry->d_name.name;
> > -       return create_new_nondir(idmap, fm, &args, dir, entry, mode);
> > +       return create_new_nondir(idmap, fm, &args, dir, entry, mode,
> > +                                default_acl, acl);
> >  }
> >
> >  static int fuse_create(struct mnt_idmap *idmap, struct inode *dir,
> > @@ -924,13 +956,17 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> >  {
> >         struct fuse_mkdir_in inarg;
> >         struct fuse_mount *fm = get_fuse_mount(dir);
> > +       struct posix_acl *default_acl, *acl;
> >         FUSE_ARGS(args);
> > +       int err;
> >
> > -       if (!fm->fc->dont_mask)
> > -               mode &= ~current_umask();
> > +       mode |= S_IFDIR;        /* vfs doesn't set S_IFDIR for us */
> > +       err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> > +       if (err)
> > +               return ERR_PTR(err);
> >
> >         memset(&inarg, 0, sizeof(inarg));
> > -       inarg.mode = mode;
> > +       inarg.mode = mode & ~S_IFDIR;
> >         inarg.umask = current_umask();
> >         args.opcode = FUSE_MKDIR;
> >         args.in_numargs = 2;
> > @@ -938,7 +974,8 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> >         args.in_args[0].value = &inarg;
> >         args.in_args[1].size = entry->d_name.len + 1;
> >         args.in_args[1].value = entry->d_name.name;
> > -       return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR);
> > +       return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR,
> > +                               default_acl, acl);
> >  }
> >
> >  static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
> > @@ -946,7 +983,14 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
> >  {
> >         struct fuse_mount *fm = get_fuse_mount(dir);
> >         unsigned len = strlen(link) + 1;
> > +       struct posix_acl *default_acl, *acl;
> > +       umode_t mode = S_IFLNK | 0777;
> >         FUSE_ARGS(args);
> > +       int err;
> > +
> > +       err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> > +       if (err)
> > +               return err;
> >
> >         args.opcode = FUSE_SYMLINK;
> >         args.in_numargs = 3;
> > @@ -955,7 +999,8 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
> >         args.in_args[1].value = entry->d_name.name;
> >         args.in_args[2].size = len;
> >         args.in_args[2].value = link;
> > -       return create_new_nondir(idmap, fm, &args, dir, entry, S_IFLNK);
> > +       return create_new_nondir(idmap, fm, &args, dir, entry, S_IFLNK,
> > +                                default_acl, acl);
> >  }
> >
> >  void fuse_flush_time_update(struct inode *inode)
> > @@ -1155,7 +1200,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir,
> >         args.in_args[0].value = &inarg;
> >         args.in_args[1].size = newent->d_name.len + 1;
> >         args.in_args[1].value = newent->d_name.name;
> > -       err = create_new_nondir(&invalid_mnt_idmap, fm, &args, newdir, newent, inode->i_mode);
> > +       err = create_new_nondir(&invalid_mnt_idmap, fm, &args, newdir, newent,
> > +                               inode->i_mode, NULL, NULL);
> >         if (!err)
> >                 fuse_update_ctime_in_cache(inode);
> >         else if (err == -EINTR)
> >
> >
> >
> 

Re: [PATCH 1/2] iomap: trace iomap_zero_iter zeroing activities

[Darrick J. Wong]

On Tue, Sep 16, 2025 at 06:49:20AM -0700, Christoph Hellwig wrote:
> On Mon, Sep 15, 2025 at 05:26:24PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > Trace which bytes actually get zeroed.
> 
> Looks good:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> 
> Can you send this out separately so that we can get it queued up ASAP?

Will do.  Thanks for the review.

--D

Re: [PATCH 2/2] iomap: error out on file IO when there is no inline_data buffer

[Darrick J. Wong]

On Tue, Sep 16, 2025 at 06:50:27AM -0700, Christoph Hellwig wrote:
> > +	if (WARN_ON_ONCE(iomap->inline_data == NULL))
> 
> Shorten this to just !iomap->inline_data instead of checking for NULL?
> 
> Same for the other two.
> 
> Otherwise this looks good, and I'd prefer to see it go upstream ASAP
> instead of hiding it in your big patch pile if possible.

Ok.  Will fix and resend as an independent series.

--D

[PATCH 2/2] iomap: error out on file IO when there is no inline_data buffer

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Return IO errors if an ->iomap_begin implementation returns an
IOMAP_INLINE buffer but forgets to set the inline_data pointer.
Filesystems should never do this, but we could help fs developers (me)
fix their bugs by handling this more gracefully than crashing the
kernel.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/iomap/buffered-io.c |   15 ++++++++++-----
 fs/iomap/direct-io.c   |    3 +++
 2 files changed, 13 insertions(+), 5 deletions(-)


diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 741f1f6001e1ff..8dd5421cb910b5 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -312,6 +312,9 @@ static int iomap_read_inline_data(const struct iomap_iter *iter,
 	size_t size = i_size_read(iter->inode) - iomap->offset;
 	size_t offset = offset_in_folio(folio, iomap->offset);
 
+	if (WARN_ON_ONCE(!iomap->inline_data))
+		return -EIO;
+
 	if (folio_test_uptodate(folio))
 		return 0;
 
@@ -913,7 +916,7 @@ static bool __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
 	return true;
 }
 
-static void iomap_write_end_inline(const struct iomap_iter *iter,
+static bool iomap_write_end_inline(const struct iomap_iter *iter,
 		struct folio *folio, loff_t pos, size_t copied)
 {
 	const struct iomap *iomap = &iter->iomap;
@@ -922,12 +925,16 @@ static void iomap_write_end_inline(const struct iomap_iter *iter,
 	WARN_ON_ONCE(!folio_test_uptodate(folio));
 	BUG_ON(!iomap_inline_data_valid(iomap));
 
+	if (WARN_ON_ONCE(!iomap->inline_data))
+		return false;
+
 	flush_dcache_folio(folio);
 	addr = kmap_local_folio(folio, pos);
 	memcpy(iomap_inline_data(iomap, pos), addr, copied);
 	kunmap_local(addr);
 
 	mark_inode_dirty(iter->inode);
+	return true;
 }
 
 /*
@@ -940,10 +947,8 @@ static bool iomap_write_end(struct iomap_iter *iter, size_t len, size_t copied,
 	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 	loff_t pos = iter->pos;
 
-	if (srcmap->type == IOMAP_INLINE) {
-		iomap_write_end_inline(iter, folio, pos, copied);
-		return true;
-	}
+	if (srcmap->type == IOMAP_INLINE)
+		return iomap_write_end_inline(iter, folio, pos, copied);
 
 	if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
 		size_t bh_written;
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 6dc4e18f93a40a..efb684bdb2cc10 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -523,6 +523,9 @@ static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio)
 	loff_t pos = iomi->pos;
 	u64 copied;
 
+	if (WARN_ON_ONCE(!inline_data))
+		return -EIO;
+
 	if (WARN_ON_ONCE(!iomap_inline_data_valid(iomap)))
 		return -EIO;
 

Re: [PATCH 1/1] libfuse: don't put HAVE_STATX in a public header

[Darrick J. Wong]

On Tue, Sep 16, 2025 at 02:38:07PM +0000, Bernd Schubert wrote:
> On 9/16/25 02:41, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > fuse.h and fuse_lowlevel.h are public headers, don't expose internal
> > build system config variables to downstream clients.  This can also lead
> > to function pointer ordering issues if (say) libfuse gets built with
> > HAVE_STATX but the client program doesn't define a HAVE_STATX.
> > 
> > Get rid of the conditionals in the public header files to fix this.
> 
> Thank you, PR with an updated commit message and removal of HAVE_STATX
> from the public libfuse_config.h created here
> https://github.com/libfuse/libfuse/pull/1333

That looks reasonable, thanks for picking this up. :)

--D

Re: [PATCH 2/2] iomap: error out on file IO when there is no inline_data buffer

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH 3/5] fuse: move the passthrough-specific code back to passthrough.c

[Amir Goldstein]

On Tue, Sep 16, 2025 at 2:27 AM Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> In preparation for iomap, move the passthrough-specific validation code
> back to passthrough.c and create a new Kconfig item for conditional
> compilation of backing.c.  In the next patch, iomap will share the
> backing structures.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  fs/fuse/fuse_i.h          |   23 +++++++++--
>  include/uapi/linux/fuse.h |    8 +++-
>  fs/fuse/Kconfig           |    4 ++
>  fs/fuse/Makefile          |    3 +
>  fs/fuse/backing.c         |   95 ++++++++++++++++++++++++++++++++++-----------
>  fs/fuse/dev.c             |    4 +-
>  fs/fuse/inode.c           |    4 +-
>  fs/fuse/passthrough.c     |   37 +++++++++++++++++-
>  8 files changed, 144 insertions(+), 34 deletions(-)
>
>
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index 52db609e63eb54..4560687d619d76 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -96,10 +96,21 @@ struct fuse_submount_lookup {
>         struct fuse_forget_link *forget;
>  };
>
> +struct fuse_conn;
> +
> +/** Operations for subsystems that want to use a backing file */
> +struct fuse_backing_ops {
> +       int (*may_admin)(struct fuse_conn *fc, uint32_t flags);
> +       int (*may_open)(struct fuse_conn *fc, struct file *file);
> +       int (*may_close)(struct fuse_conn *fc, struct file *file);
> +       unsigned int type;
> +};
> +
>  /** Container for data related to mapping to backing file */
>  struct fuse_backing {
>         struct file *file;
>         struct cred *cred;
> +       const struct fuse_backing_ops *ops;

Please argue why we need a mix of passthrough backing
files and iomap backing bdev on the same filesystem.

Same as my argument against passthrough/iomap on
same fuse_backing:
If you do not plan to test it, and nobody asked for it, please do
not allow it - it's bad for code test coverage.

I think at this point in time FUSE_PASSTHROUGH and
FUSE_IOMAP should be mutually exclusive and
fuse_backing_ops could be set at fc level.
If we want to move them for per fuse_backing later
we can always do that when the use cases and tests arrive.

Thanks,
Amir.

>
>         /** refcount */
>         refcount_t count;
> @@ -968,7 +979,7 @@ struct fuse_conn {
>         /* New writepages go into this bucket */
>         struct fuse_sync_bucket __rcu *curr_bucket;
>
> -#ifdef CONFIG_FUSE_PASSTHROUGH
> +#ifdef CONFIG_FUSE_BACKING
>         /** IDR for backing files ids */
>         struct idr backing_files_map;
>  #endif
> @@ -1571,10 +1582,12 @@ void fuse_file_release(struct inode *inode, struct fuse_file *ff,
>                        unsigned int open_flags, fl_owner_t id, bool isdir);
>
>  /* backing.c */
> -#ifdef CONFIG_FUSE_PASSTHROUGH
> +#ifdef CONFIG_FUSE_BACKING
>  struct fuse_backing *fuse_backing_get(struct fuse_backing *fb);
>  void fuse_backing_put(struct fuse_backing *fb);
> -struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id);
> +struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
> +                                        const struct fuse_backing_ops *ops,
> +                                        int backing_id);
>  #else
>
>  static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
> @@ -1631,6 +1644,10 @@ static inline struct file *fuse_file_passthrough(struct fuse_file *ff)
>  #endif
>  }
>
> +#ifdef CONFIG_FUSE_PASSTHROUGH
> +extern const struct fuse_backing_ops fuse_passthrough_backing_ops;
> +#endif
> +
>  ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter);
>  ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, struct iov_iter *iter);
>  ssize_t fuse_passthrough_splice_read(struct file *in, loff_t *ppos,
> diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> index 1d76d0332f46f6..31b80f93211b81 100644
> --- a/include/uapi/linux/fuse.h
> +++ b/include/uapi/linux/fuse.h
> @@ -1114,9 +1114,15 @@ struct fuse_notify_retrieve_in {
>         uint64_t        dummy4;
>  };
>
> +#define FUSE_BACKING_TYPE_MASK         (0xFF)
> +#define FUSE_BACKING_TYPE_PASSTHROUGH  (0)
> +#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_PASSTHROUGH)
> +
> +#define FUSE_BACKING_FLAGS_ALL         (FUSE_BACKING_TYPE_MASK)
> +
>  struct fuse_backing_map {
>         int32_t         fd;
> -       uint32_t        flags;
> +       uint32_t        flags; /* FUSE_BACKING_* */
>         uint64_t        padding;
>  };
>
> diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> index a774166264de69..9563fa5387a241 100644
> --- a/fs/fuse/Kconfig
> +++ b/fs/fuse/Kconfig
> @@ -59,12 +59,16 @@ config FUSE_PASSTHROUGH
>         default y
>         depends on FUSE_FS
>         select FS_STACK
> +       select FUSE_BACKING
>         help
>           This allows bypassing FUSE server by mapping specific FUSE operations
>           to be performed directly on a backing file.
>
>           If you want to allow passthrough operations, answer Y.
>
> +config FUSE_BACKING
> +       bool
> +
>  config FUSE_IO_URING
>         bool "FUSE communication over io-uring"
>         default y
> diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
> index 8ddd8f0b204ee5..36be6d715b111a 100644
> --- a/fs/fuse/Makefile
> +++ b/fs/fuse/Makefile
> @@ -13,7 +13,8 @@ obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
>  fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
>  fuse-y += iomode.o
>  fuse-$(CONFIG_FUSE_DAX) += dax.o
> -fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o backing.o
> +fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
> +fuse-$(CONFIG_FUSE_BACKING) += backing.o
>  fuse-$(CONFIG_SYSCTL) += sysctl.o
>  fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
>
> diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
> index 4afda419dd1416..da0dff288396ed 100644
> --- a/fs/fuse/backing.c
> +++ b/fs/fuse/backing.c
> @@ -6,6 +6,7 @@
>   */
>
>  #include "fuse_i.h"
> +#include "fuse_trace.h"
>
>  #include <linux/file.h>
>
> @@ -69,32 +70,53 @@ static int fuse_backing_id_free(int id, void *p, void *data)
>         struct fuse_backing *fb = p;
>
>         WARN_ON_ONCE(refcount_read(&fb->count) != 1);
> +
>         fuse_backing_free(fb);
>         return 0;
>  }
>
>  void fuse_backing_files_free(struct fuse_conn *fc)
>  {
> -       idr_for_each(&fc->backing_files_map, fuse_backing_id_free, NULL);
> +       idr_for_each(&fc->backing_files_map, fuse_backing_id_free, fc);
>         idr_destroy(&fc->backing_files_map);
>  }
>
> +static inline const struct fuse_backing_ops *
> +fuse_backing_ops_from_map(const struct fuse_backing_map *map)
> +{
> +       switch (map->flags & FUSE_BACKING_TYPE_MASK) {
> +#ifdef CONFIG_FUSE_PASSTHROUGH
> +       case FUSE_BACKING_TYPE_PASSTHROUGH:
> +               return &fuse_passthrough_backing_ops;
> +#endif
> +       default:
> +               break;
> +       }
> +
> +       return NULL;
> +}
> +
>  int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
>  {
>         struct file *file;
> -       struct super_block *backing_sb;
>         struct fuse_backing *fb = NULL;
> +       const struct fuse_backing_ops *ops = fuse_backing_ops_from_map(map);
> +       uint32_t op_flags = map->flags & ~FUSE_BACKING_TYPE_MASK;
>         int res;
>
>         pr_debug("%s: fd=%d flags=0x%x\n", __func__, map->fd, map->flags);
>
> -       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
> -       res = -EPERM;
> -       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
> +       res = -EOPNOTSUPP;
> +       if (!ops)
> +               goto out;
> +       WARN_ON(ops->type != (map->flags & FUSE_BACKING_TYPE_MASK));
> +
> +       res = ops->may_admin ? ops->may_admin(fc, op_flags) : 0;
> +       if (res)
>                 goto out;
>
>         res = -EINVAL;
> -       if (map->flags || map->padding)
> +       if (map->padding)
>                 goto out;
>
>         file = fget_raw(map->fd);
> @@ -102,14 +124,8 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
>         if (!file)
>                 goto out;
>
> -       /* read/write/splice/mmap passthrough only relevant for regular files */
> -       res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
> -       if (!d_is_reg(file->f_path.dentry))
> -               goto out_fput;
> -
> -       backing_sb = file_inode(file)->i_sb;
> -       res = -ELOOP;
> -       if (backing_sb->s_stack_depth >= fc->max_stack_depth)
> +       res = ops->may_open ? ops->may_open(fc, file) : 0;
> +       if (res)
>                 goto out_fput;
>
>         fb = kmalloc(sizeof(struct fuse_backing), GFP_KERNEL);
> @@ -119,14 +135,15 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
>
>         fb->file = file;
>         fb->cred = prepare_creds();
> +       fb->ops = ops;
>         refcount_set(&fb->count, 1);
>
>         res = fuse_backing_id_alloc(fc, fb);
>         if (res < 0) {
>                 fuse_backing_free(fb);
>                 fb = NULL;
> +               goto out;
>         }
> -
>  out:
>         pr_debug("%s: fb=0x%p, ret=%i\n", __func__, fb, res);
>
> @@ -137,41 +154,71 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
>         goto out;
>  }
>
> +static struct fuse_backing *__fuse_backing_lookup(struct fuse_conn *fc,
> +                                                 int backing_id)
> +{
> +       struct fuse_backing *fb;
> +
> +       rcu_read_lock();
> +       fb = idr_find(&fc->backing_files_map, backing_id);
> +       fb = fuse_backing_get(fb);
> +       rcu_read_unlock();
> +
> +       return fb;
> +}
> +
>  int fuse_backing_close(struct fuse_conn *fc, int backing_id)
>  {
> -       struct fuse_backing *fb = NULL;
> +       struct fuse_backing *fb, *test_fb;
> +       const struct fuse_backing_ops *ops;
>         int err;
>
>         pr_debug("%s: backing_id=%d\n", __func__, backing_id);
>
> -       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
> -       err = -EPERM;
> -       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
> -               goto out;
> -
>         err = -EINVAL;
>         if (backing_id <= 0)
>                 goto out;
>
>         err = -ENOENT;
> -       fb = fuse_backing_id_remove(fc, backing_id);
> +       fb = __fuse_backing_lookup(fc, backing_id);
>         if (!fb)
>                 goto out;
> +       ops = fb->ops;
>
> -       fuse_backing_put(fb);
> +       err = ops->may_admin ? ops->may_admin(fc, 0) : 0;
> +       if (err)
> +               goto out_fb;
> +
> +       err = ops->may_close ? ops->may_close(fc, fb->file) : 0;
> +       if (err)
> +               goto out_fb;
> +
> +       err = -ENOENT;
> +       test_fb = fuse_backing_id_remove(fc, backing_id);
> +       if (!test_fb)
> +               goto out_fb;
> +
> +       WARN_ON(fb != test_fb);
>         err = 0;
> +       fuse_backing_put(test_fb);
> +out_fb:
> +       fuse_backing_put(fb);
>  out:
>         pr_debug("%s: fb=0x%p, err=%i\n", __func__, fb, err);
>
>         return err;
>  }
>
> -struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id)
> +struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
> +                                        const struct fuse_backing_ops *ops,
> +                                        int backing_id)
>  {
>         struct fuse_backing *fb;
>
>         rcu_read_lock();
>         fb = idr_find(&fc->backing_files_map, backing_id);
> +       if (fb && fb->ops != ops)
> +               fb = NULL;
>         fb = fuse_backing_get(fb);
>         rcu_read_unlock();
>
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index e5aaf0c668bc11..281bc81f3b448b 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -2654,7 +2654,7 @@ static long fuse_dev_ioctl_backing_open(struct file *file,
>         if (IS_ERR(fud))
>                 return PTR_ERR(fud);
>
> -       if (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
> +       if (!IS_ENABLED(CONFIG_FUSE_BACKING))
>                 return -EOPNOTSUPP;
>
>         if (copy_from_user(&map, argp, sizeof(map)))
> @@ -2671,7 +2671,7 @@ static long fuse_dev_ioctl_backing_close(struct file *file, __u32 __user *argp)
>         if (IS_ERR(fud))
>                 return PTR_ERR(fud);
>
> -       if (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
> +       if (!IS_ENABLED(CONFIG_FUSE_BACKING))
>                 return -EOPNOTSUPP;
>
>         if (get_user(backing_id, argp))
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index 14c35ce12b87d6..1e7298b2b89b58 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -995,7 +995,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
>         fc->name_max = FUSE_NAME_LOW_MAX;
>         fc->timeout.req_timeout = 0;
>
> -       if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
> +       if (IS_ENABLED(CONFIG_FUSE_BACKING))
>                 fuse_backing_files_init(fc);
>
>         INIT_LIST_HEAD(&fc->mounts);
> @@ -1032,7 +1032,7 @@ void fuse_conn_put(struct fuse_conn *fc)
>                         WARN_ON(atomic_read(&bucket->count) != 1);
>                         kfree(bucket);
>                 }
> -               if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
> +               if (IS_ENABLED(CONFIG_FUSE_BACKING))
>                         fuse_backing_files_free(fc);
>                 call_rcu(&fc->rcu, delayed_release);
>         }
> diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c
> index e0b8d885bc81f3..9792d7b12a775b 100644
> --- a/fs/fuse/passthrough.c
> +++ b/fs/fuse/passthrough.c
> @@ -164,7 +164,7 @@ struct fuse_backing *fuse_passthrough_open(struct file *file,
>                 goto out;
>
>         err = -ENOENT;
> -       fb = fuse_backing_lookup(fc, backing_id);
> +       fb = fuse_backing_lookup(fc, &fuse_passthrough_backing_ops, backing_id);
>         if (!fb)
>                 goto out;
>
> @@ -197,3 +197,38 @@ void fuse_passthrough_release(struct fuse_file *ff, struct fuse_backing *fb)
>         put_cred(ff->cred);
>         ff->cred = NULL;
>  }
> +
> +static int fuse_passthrough_may_admin(struct fuse_conn *fc, unsigned int flags)
> +{
> +       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
> +       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
> +               return -EPERM;
> +
> +       if (flags)
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +
> +static int fuse_passthrough_may_open(struct fuse_conn *fc, struct file *file)
> +{
> +       struct super_block *backing_sb;
> +       int res;
> +
> +       /* read/write/splice/mmap passthrough only relevant for regular files */
> +       res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
> +       if (!d_is_reg(file->f_path.dentry))
> +               return res;
> +
> +       backing_sb = file_inode(file)->i_sb;
> +       if (backing_sb->s_stack_depth >= fc->max_stack_depth)
> +               return -ELOOP;
> +
> +       return 0;
> +}
> +
> +const struct fuse_backing_ops fuse_passthrough_backing_ops = {
> +       .type = FUSE_BACKING_TYPE_PASSTHROUGH,
> +       .may_admin = fuse_passthrough_may_admin,
> +       .may_open = fuse_passthrough_may_open,
> +};
>
>

Re: [PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Amir Goldstein]

On Tue, Sep 16, 2025 at 2:30 AM Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> Enable the use of the backing file open/close ioctls so that fuse
> servers can register block devices for use with iomap.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  fs/fuse/fuse_i.h          |    5 ++
>  include/uapi/linux/fuse.h |    3 +
>  fs/fuse/Kconfig           |    1
>  fs/fuse/backing.c         |   12 +++++
>  fs/fuse/file_iomap.c      |   99 +++++++++++++++++++++++++++++++++++++++++----
>  fs/fuse/trace.c           |    1
>  6 files changed, 111 insertions(+), 10 deletions(-)
>
>
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index 389b123f0bf144..791f210c13a876 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -97,12 +97,14 @@ struct fuse_submount_lookup {
>  };
>
>  struct fuse_conn;
> +struct fuse_backing;
>
>  /** Operations for subsystems that want to use a backing file */
>  struct fuse_backing_ops {
>         int (*may_admin)(struct fuse_conn *fc, uint32_t flags);
>         int (*may_open)(struct fuse_conn *fc, struct file *file);
>         int (*may_close)(struct fuse_conn *fc, struct file *file);
> +       int (*post_open)(struct fuse_conn *fc, struct fuse_backing *fb);
>         unsigned int type;
>  };
>
> @@ -110,6 +112,7 @@ struct fuse_backing_ops {
>  struct fuse_backing {
>         struct file *file;
>         struct cred *cred;
> +       struct block_device *bdev;
>         const struct fuse_backing_ops *ops;
>
>         /** refcount */
> @@ -1704,6 +1707,8 @@ static inline bool fuse_has_iomap(const struct inode *inode)
>  {
>         return get_fuse_conn_c(inode)->iomap;
>  }
> +
> +extern const struct fuse_backing_ops fuse_iomap_backing_ops;
>  #else
>  # define fuse_iomap_enabled(...)               (false)
>  # define fuse_has_iomap(...)                   (false)
> diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> index 3634cbe602cd9c..3a367f387795ff 100644
> --- a/include/uapi/linux/fuse.h
> +++ b/include/uapi/linux/fuse.h
> @@ -1124,7 +1124,8 @@ struct fuse_notify_retrieve_in {
>
>  #define FUSE_BACKING_TYPE_MASK         (0xFF)
>  #define FUSE_BACKING_TYPE_PASSTHROUGH  (0)
> -#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_PASSTHROUGH)
> +#define FUSE_BACKING_TYPE_IOMAP                (1)
> +#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_IOMAP)
>
>  #define FUSE_BACKING_FLAGS_ALL         (FUSE_BACKING_TYPE_MASK)
>
> diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> index 52e1a04183e760..baa38cf0f295ff 100644
> --- a/fs/fuse/Kconfig
> +++ b/fs/fuse/Kconfig
> @@ -75,6 +75,7 @@ config FUSE_IOMAP
>         depends on FUSE_FS
>         depends on BLOCK
>         select FS_IOMAP
> +       select FUSE_BACKING
>         help
>           Enable fuse servers to operate the regular file I/O path through
>           the fs-iomap library in the kernel.  This enables higher performance
> diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
> index 229c101ab46b0e..fc58636ac78eaa 100644
> --- a/fs/fuse/backing.c
> +++ b/fs/fuse/backing.c
> @@ -89,6 +89,10 @@ fuse_backing_ops_from_map(const struct fuse_backing_map *map)
>  #ifdef CONFIG_FUSE_PASSTHROUGH
>         case FUSE_BACKING_TYPE_PASSTHROUGH:
>                 return &fuse_passthrough_backing_ops;
> +#endif
> +#ifdef CONFIG_FUSE_IOMAP
> +       case FUSE_BACKING_TYPE_IOMAP:
> +               return &fuse_iomap_backing_ops;
>  #endif
>         default:
>                 break;
> @@ -137,8 +141,16 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
>         fb->file = file;
>         fb->cred = prepare_creds();
>         fb->ops = ops;
> +       fb->bdev = NULL;
>         refcount_set(&fb->count, 1);
>
> +       res = ops->post_open ? ops->post_open(fc, fb) : 0;
> +       if (res) {
> +               fuse_backing_free(fb);
> +               fb = NULL;
> +               goto out;
> +       }
> +
>         res = fuse_backing_id_alloc(fc, fb);
>         if (res < 0) {
>                 fuse_backing_free(fb);
> diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> index e7d19e2aee4541..3a4161633add0e 100644
> --- a/fs/fuse/file_iomap.c
> +++ b/fs/fuse/file_iomap.c
> @@ -319,10 +319,6 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
>                 return false;
>         }
>
> -       /* XXX: we don't support devices yet */
> -       if (BAD_DATA(map->dev != FUSE_IOMAP_DEV_NULL))
> -               return false;
> -
>         /* No overflows in the device range, if supplied */
>         if (map->addr != FUSE_IOMAP_NULL_ADDR &&
>             BAD_DATA(check_add_overflow(map->addr, map->length, &end)))
> @@ -334,6 +330,7 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
>  /* Convert a mapping from the server into something the kernel can use */
>  static inline void fuse_iomap_from_server(struct inode *inode,
>                                           struct iomap *iomap,
> +                                         const struct fuse_backing *fb,
>                                           const struct fuse_iomap_io *fmap)
>  {
>         iomap->addr = fmap->addr;
> @@ -341,7 +338,9 @@ static inline void fuse_iomap_from_server(struct inode *inode,
>         iomap->length = fmap->length;
>         iomap->type = fuse_iomap_type_from_server(fmap->type);
>         iomap->flags = fuse_iomap_flags_from_server(fmap->flags);
> -       iomap->bdev = inode->i_sb->s_bdev; /* XXX */
> +
> +       iomap->bdev = fb ? fb->bdev : NULL;
> +       iomap->dax_dev = NULL;
>  }
>
>  /* Convert a mapping from the kernel into something the server can use */
> @@ -392,6 +391,27 @@ static inline bool fuse_is_iomap_file_write(unsigned int opflags)
>         return opflags & (IOMAP_WRITE | IOMAP_ZERO | IOMAP_UNSHARE);
>  }
>
> +static inline struct fuse_backing *
> +fuse_iomap_find_dev(struct fuse_conn *fc, const struct fuse_iomap_io *map)
> +{
> +       struct fuse_backing *ret = NULL;
> +
> +       if (map->dev != FUSE_IOMAP_DEV_NULL && map->dev < INT_MAX)
> +               ret = fuse_backing_lookup(fc, &fuse_iomap_backing_ops,
> +                                         map->dev);
> +
> +       switch (map->type) {
> +       case FUSE_IOMAP_TYPE_MAPPED:
> +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> +               /* Mappings backed by space must have a device/addr */
> +               if (BAD_DATA(ret == NULL))
> +                       return ERR_PTR(-EFSCORRUPTED);
> +               break;
> +       }
> +
> +       return ret;
> +}
> +
>  static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
>                             unsigned opflags, struct iomap *iomap,
>                             struct iomap *srcmap)
> @@ -405,6 +425,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
>         };
>         struct fuse_iomap_begin_out outarg = { };
>         struct fuse_mount *fm = get_fuse_mount(inode);
> +       struct fuse_backing *read_dev = NULL;
> +       struct fuse_backing *write_dev = NULL;
>         FUSE_ARGS(args);
>         int err;
>
> @@ -431,24 +453,44 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
>         if (err)
>                 return err;
>
> +       read_dev = fuse_iomap_find_dev(fm->fc, &outarg.read);
> +       if (IS_ERR(read_dev))
> +               return PTR_ERR(read_dev);
> +
>         if (fuse_is_iomap_file_write(opflags) &&
>             outarg.write.type != FUSE_IOMAP_TYPE_PURE_OVERWRITE) {
> +               /* open the write device */
> +               write_dev = fuse_iomap_find_dev(fm->fc, &outarg.write);
> +               if (IS_ERR(write_dev)) {
> +                       err = PTR_ERR(write_dev);
> +                       goto out_read_dev;
> +               }
> +
>                 /*
>                  * For an out of place write, we must supply the write mapping
>                  * via @iomap, and the read mapping via @srcmap.
>                  */
> -               fuse_iomap_from_server(inode, iomap, &outarg.write);
> -               fuse_iomap_from_server(inode, srcmap, &outarg.read);
> +               fuse_iomap_from_server(inode, iomap, write_dev, &outarg.write);
> +               fuse_iomap_from_server(inode, srcmap, read_dev, &outarg.read);
>         } else {
>                 /*
>                  * For everything else (reads, reporting, and pure overwrites),
>                  * we can return the sole mapping through @iomap and leave
>                  * @srcmap unchanged from its default (HOLE).
>                  */
> -               fuse_iomap_from_server(inode, iomap, &outarg.read);
> +               fuse_iomap_from_server(inode, iomap, read_dev, &outarg.read);
>         }
>
> -       return 0;
> +       /*
> +        * XXX: if we ever want to support closing devices, we need a way to
> +        * track the fuse_backing refcount all the way through bio endios.
> +        * For now we put the refcount here because you can't remove an iomap
> +        * device until unmount time.
> +        */
> +       fuse_backing_put(write_dev);
> +out_read_dev:
> +       fuse_backing_put(read_dev);
> +       return err;
>  }
>
>  /* Decide if we send FUSE_IOMAP_END to the fuse server */
> @@ -523,3 +565,42 @@ const struct iomap_ops fuse_iomap_ops = {
>         .iomap_begin            = fuse_iomap_begin,
>         .iomap_end              = fuse_iomap_end,
>  };
> +
> +static int fuse_iomap_may_admin(struct fuse_conn *fc, unsigned int flags)
> +{
> +       if (!fc->iomap)
> +               return -EPERM;
> +

IIRC, on RFC I asked why is iomap exempt from CAP_SYS_ADMIN
check. If there was a good reason, I forgot it.

The problem is that while fuse-iomap fs is only expected to open
a handful of backing devs, we would like to prevent abuse of this ioctl
by a buggy or malicious user.

I think that if you want to avoid CAP_SYS_ADMIN here you should
enforce a limit on the number of backing bdevs.

If you accept my suggestion to mutually exclude passthrough and
iomap features per fs, then you'd just need to keep track on numbers
of fuse_backing ids and place a limit for iomap fs.

BTW, I think it is enough keep track of the number of backing ids
and no need to keep track of the number of fuse_backing objects
(which can outlive a backing id), because an "anonymous" fuse_backing
object is always associated with an open fuse file - that's the same as
an overlayfs backing file, which is not accounted for in ulimit.

Thanks,
Amir.

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Joanne Koong]

On Mon, Sep 15, 2025 at 5:25 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> Create a new fuse context flag that indicates that the kernel should
> implement various local filesystem behaviors instead of passing vfs
> commands straight through to the fuse server and expecting the server to
> do all the work.  For example, this means that we'll use the kernel to
> transform some ACL updates into mode changes, and later to do
> enforcement of the immutable and append iflags.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  fs/fuse/fuse_i.h |    4 ++++
>  fs/fuse/inode.c  |    2 ++
>  2 files changed, 6 insertions(+)
>
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index e93a3c3f11d901..e13e8270f4f58d 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -603,6 +603,7 @@ struct fuse_fs_context {
>         bool no_control:1;
>         bool no_force_umount:1;
>         bool legacy_opts_show:1;
> +       bool local_fs:1;
>         enum fuse_dax_mode dax_mode;
>         unsigned int max_read;
>         unsigned int blksize;
> @@ -901,6 +902,9 @@ struct fuse_conn {
>         /* Is link not implemented by fs? */
>         unsigned int no_link:1;
>
> +       /* Should this filesystem behave like a local filesystem? */
> +       unsigned int local_fs:1;
> +
>         /* Use io_uring for communication */
>         unsigned int io_uring;
>
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index c94aba627a6f11..c8dd0bcb7e6f9f 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -1862,6 +1862,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
>         fc->destroy = ctx->destroy;
>         fc->no_control = ctx->no_control;
>         fc->no_force_umount = ctx->no_force_umount;
> +       fc->local_fs = ctx->local_fs;
>

If I'm understanding it correctly, fc->local_fs is set to true if it's
a fuseblk device? Why do we need a new "ctx->local_fs" instead of
reusing ctx->is_bdev?

Thanks,
Joanne

>         err = -ENOMEM;
>         root = fuse_get_root_inode(sb, ctx->rootmode);
> @@ -2029,6 +2030,7 @@ static int fuse_init_fs_context(struct fs_context *fsc)
>         if (fsc->fs_type == &fuseblk_fs_type) {
>                 ctx->is_bdev = true;
>                 ctx->destroy = true;
> +               ctx->local_fs = true;
>         }
>  #endif
>
>

Re: [PATCH 1/5] fuse: allow synchronous FUSE_INIT

[Joanne Koong]

On Mon, Sep 15, 2025 at 5:26 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Miklos Szeredi <mszeredi@redhat.com>
>
> FUSE_INIT has always been asynchronous with mount.  That means that the
> server processed this request after the mount syscall returned.
>
> This means that FUSE_INIT can't supply the root inode's ID, hence it
> currently has a hardcoded value.  There are other limitations such as not
> being able to perform getxattr during mount, which is needed by selinux.
>
> To remove these limitations allow server to process FUSE_INIT while
> initializing the in-core super block for the fuse filesystem.  This can
> only be done if the server is prepared to handle this, so add
> FUSE_DEV_IOC_SYNC_INIT ioctl, which
>
>  a) lets the server know whether this feature is supported, returning
>  ENOTTY othewrwise.
>
>  b) lets the kernel know to perform a synchronous initialization
>
> The implementation is slightly tricky, since fuse_dev/fuse_conn are set up
> only during super block creation.  This is solved by setting the private
> data of the fuse device file to a special value ((struct fuse_dev *) 1) and
> waiting for this to be turned into a proper fuse_dev before commecing with
> operations on the device file.
>
> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  fs/fuse/fuse_dev_i.h      |   13 +++++++-
>  fs/fuse/fuse_i.h          |    5 ++-
>  include/uapi/linux/fuse.h |    1 +
>  fs/fuse/cuse.c            |    3 +-
>  fs/fuse/dev.c             |   74 +++++++++++++++++++++++++++++++++------------
>  fs/fuse/dev_uring.c       |    4 +-
>  fs/fuse/inode.c           |   50 ++++++++++++++++++++++++------
>  7 files changed, 115 insertions(+), 35 deletions(-)

btw, I think an updated version of this has already been merged into
the fuse for-next tree (commit dfb84c330794)

Thanks,
Joanne

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Darrick J. Wong]

On Wed, Sep 17, 2025 at 10:18:40AM -0700, Joanne Koong wrote:
> On Mon, Sep 15, 2025 at 5:25 PM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > From: Darrick J. Wong <djwong@kernel.org>
> >
> > Create a new fuse context flag that indicates that the kernel should
> > implement various local filesystem behaviors instead of passing vfs
> > commands straight through to the fuse server and expecting the server to
> > do all the work.  For example, this means that we'll use the kernel to
> > transform some ACL updates into mode changes, and later to do
> > enforcement of the immutable and append iflags.
> >
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  fs/fuse/fuse_i.h |    4 ++++
> >  fs/fuse/inode.c  |    2 ++
> >  2 files changed, 6 insertions(+)
> >
> > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > index e93a3c3f11d901..e13e8270f4f58d 100644
> > --- a/fs/fuse/fuse_i.h
> > +++ b/fs/fuse/fuse_i.h
> > @@ -603,6 +603,7 @@ struct fuse_fs_context {
> >         bool no_control:1;
> >         bool no_force_umount:1;
> >         bool legacy_opts_show:1;
> > +       bool local_fs:1;
> >         enum fuse_dax_mode dax_mode;
> >         unsigned int max_read;
> >         unsigned int blksize;
> > @@ -901,6 +902,9 @@ struct fuse_conn {
> >         /* Is link not implemented by fs? */
> >         unsigned int no_link:1;
> >
> > +       /* Should this filesystem behave like a local filesystem? */
> > +       unsigned int local_fs:1;
> > +
> >         /* Use io_uring for communication */
> >         unsigned int io_uring;
> >
> > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > index c94aba627a6f11..c8dd0bcb7e6f9f 100644
> > --- a/fs/fuse/inode.c
> > +++ b/fs/fuse/inode.c
> > @@ -1862,6 +1862,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
> >         fc->destroy = ctx->destroy;
> >         fc->no_control = ctx->no_control;
> >         fc->no_force_umount = ctx->no_force_umount;
> > +       fc->local_fs = ctx->local_fs;
> >
> 
> If I'm understanding it correctly, fc->local_fs is set to true if it's
> a fuseblk device? Why do we need a new "ctx->local_fs" instead of
> reusing ctx->is_bdev?

Eventually, enabling iomap will also set local_fs=1, as Miklos and I
sort of touched on a couple weeks ago:

https://lore.kernel.org/linux-fsdevel/CAJfpegvmXnZc=nC4UGw5Gya2cAr-kR0s=WNecnMhdTM_mGyuUg@mail.gmail.com/

--D

> Thanks,
> Joanne
> 
> >         err = -ENOMEM;
> >         root = fuse_get_root_inode(sb, ctx->rootmode);
> > @@ -2029,6 +2030,7 @@ static int fuse_init_fs_context(struct fs_context *fsc)
> >         if (fsc->fs_type == &fuseblk_fs_type) {
> >                 ctx->is_bdev = true;
> >                 ctx->destroy = true;
> > +               ctx->local_fs = true;
> >         }
> >  #endif
> >
> >

Re: [PATCH 3/5] fuse: move the passthrough-specific code back to passthrough.c

[Darrick J. Wong]

On Wed, Sep 17, 2025 at 04:47:19AM +0200, Amir Goldstein wrote:
> On Tue, Sep 16, 2025 at 2:27 AM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > From: Darrick J. Wong <djwong@kernel.org>
> >
> > In preparation for iomap, move the passthrough-specific validation code
> > back to passthrough.c and create a new Kconfig item for conditional
> > compilation of backing.c.  In the next patch, iomap will share the
> > backing structures.
> >
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  fs/fuse/fuse_i.h          |   23 +++++++++--
> >  include/uapi/linux/fuse.h |    8 +++-
> >  fs/fuse/Kconfig           |    4 ++
> >  fs/fuse/Makefile          |    3 +
> >  fs/fuse/backing.c         |   95 ++++++++++++++++++++++++++++++++++-----------
> >  fs/fuse/dev.c             |    4 +-
> >  fs/fuse/inode.c           |    4 +-
> >  fs/fuse/passthrough.c     |   37 +++++++++++++++++-
> >  8 files changed, 144 insertions(+), 34 deletions(-)
> >
> >
> > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > index 52db609e63eb54..4560687d619d76 100644
> > --- a/fs/fuse/fuse_i.h
> > +++ b/fs/fuse/fuse_i.h
> > @@ -96,10 +96,21 @@ struct fuse_submount_lookup {
> >         struct fuse_forget_link *forget;
> >  };
> >
> > +struct fuse_conn;
> > +
> > +/** Operations for subsystems that want to use a backing file */
> > +struct fuse_backing_ops {
> > +       int (*may_admin)(struct fuse_conn *fc, uint32_t flags);
> > +       int (*may_open)(struct fuse_conn *fc, struct file *file);
> > +       int (*may_close)(struct fuse_conn *fc, struct file *file);
> > +       unsigned int type;
> > +};
> > +
> >  /** Container for data related to mapping to backing file */
> >  struct fuse_backing {
> >         struct file *file;
> >         struct cred *cred;
> > +       const struct fuse_backing_ops *ops;
> 
> Please argue why we need a mix of passthrough backing
> files and iomap backing bdev on the same filesystem.

I've no particular reason to allow both on the same filesystem.  I
simply didn't want to add restrictions to existing functionality.

> Same as my argument against passthrough/iomap on
> same fuse_backing:
> If you do not plan to test it, and nobody asked for it, please do
> not allow it - it's bad for code test coverage.
> 
> I think at this point in time FUSE_PASSTHROUGH and
> FUSE_IOMAP should be mutually exclusive and
> fuse_backing_ops could be set at fc level.
> If we want to move them for per fuse_backing later
> we can always do that when the use cases and tests arrive.

With Miklos' ok I'll constrain fuse not to allow passthrough and iomap
files on the same filesystem, but as it is now there's no technical
reason to make it so that they can't coexist.

--D

> Thanks,
> Amir.
> 
> >
> >         /** refcount */
> >         refcount_t count;
> > @@ -968,7 +979,7 @@ struct fuse_conn {
> >         /* New writepages go into this bucket */
> >         struct fuse_sync_bucket __rcu *curr_bucket;
> >
> > -#ifdef CONFIG_FUSE_PASSTHROUGH
> > +#ifdef CONFIG_FUSE_BACKING
> >         /** IDR for backing files ids */
> >         struct idr backing_files_map;
> >  #endif
> > @@ -1571,10 +1582,12 @@ void fuse_file_release(struct inode *inode, struct fuse_file *ff,
> >                        unsigned int open_flags, fl_owner_t id, bool isdir);
> >
> >  /* backing.c */
> > -#ifdef CONFIG_FUSE_PASSTHROUGH
> > +#ifdef CONFIG_FUSE_BACKING
> >  struct fuse_backing *fuse_backing_get(struct fuse_backing *fb);
> >  void fuse_backing_put(struct fuse_backing *fb);
> > -struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id);
> > +struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
> > +                                        const struct fuse_backing_ops *ops,
> > +                                        int backing_id);
> >  #else
> >
> >  static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
> > @@ -1631,6 +1644,10 @@ static inline struct file *fuse_file_passthrough(struct fuse_file *ff)
> >  #endif
> >  }
> >
> > +#ifdef CONFIG_FUSE_PASSTHROUGH
> > +extern const struct fuse_backing_ops fuse_passthrough_backing_ops;
> > +#endif
> > +
> >  ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter);
> >  ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, struct iov_iter *iter);
> >  ssize_t fuse_passthrough_splice_read(struct file *in, loff_t *ppos,
> > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > index 1d76d0332f46f6..31b80f93211b81 100644
> > --- a/include/uapi/linux/fuse.h
> > +++ b/include/uapi/linux/fuse.h
> > @@ -1114,9 +1114,15 @@ struct fuse_notify_retrieve_in {
> >         uint64_t        dummy4;
> >  };
> >
> > +#define FUSE_BACKING_TYPE_MASK         (0xFF)
> > +#define FUSE_BACKING_TYPE_PASSTHROUGH  (0)
> > +#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_PASSTHROUGH)
> > +
> > +#define FUSE_BACKING_FLAGS_ALL         (FUSE_BACKING_TYPE_MASK)
> > +
> >  struct fuse_backing_map {
> >         int32_t         fd;
> > -       uint32_t        flags;
> > +       uint32_t        flags; /* FUSE_BACKING_* */
> >         uint64_t        padding;
> >  };
> >
> > diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> > index a774166264de69..9563fa5387a241 100644
> > --- a/fs/fuse/Kconfig
> > +++ b/fs/fuse/Kconfig
> > @@ -59,12 +59,16 @@ config FUSE_PASSTHROUGH
> >         default y
> >         depends on FUSE_FS
> >         select FS_STACK
> > +       select FUSE_BACKING
> >         help
> >           This allows bypassing FUSE server by mapping specific FUSE operations
> >           to be performed directly on a backing file.
> >
> >           If you want to allow passthrough operations, answer Y.
> >
> > +config FUSE_BACKING
> > +       bool
> > +
> >  config FUSE_IO_URING
> >         bool "FUSE communication over io-uring"
> >         default y
> > diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
> > index 8ddd8f0b204ee5..36be6d715b111a 100644
> > --- a/fs/fuse/Makefile
> > +++ b/fs/fuse/Makefile
> > @@ -13,7 +13,8 @@ obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
> >  fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
> >  fuse-y += iomode.o
> >  fuse-$(CONFIG_FUSE_DAX) += dax.o
> > -fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o backing.o
> > +fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
> > +fuse-$(CONFIG_FUSE_BACKING) += backing.o
> >  fuse-$(CONFIG_SYSCTL) += sysctl.o
> >  fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
> >
> > diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
> > index 4afda419dd1416..da0dff288396ed 100644
> > --- a/fs/fuse/backing.c
> > +++ b/fs/fuse/backing.c
> > @@ -6,6 +6,7 @@
> >   */
> >
> >  #include "fuse_i.h"
> > +#include "fuse_trace.h"
> >
> >  #include <linux/file.h>
> >
> > @@ -69,32 +70,53 @@ static int fuse_backing_id_free(int id, void *p, void *data)
> >         struct fuse_backing *fb = p;
> >
> >         WARN_ON_ONCE(refcount_read(&fb->count) != 1);
> > +
> >         fuse_backing_free(fb);
> >         return 0;
> >  }
> >
> >  void fuse_backing_files_free(struct fuse_conn *fc)
> >  {
> > -       idr_for_each(&fc->backing_files_map, fuse_backing_id_free, NULL);
> > +       idr_for_each(&fc->backing_files_map, fuse_backing_id_free, fc);
> >         idr_destroy(&fc->backing_files_map);
> >  }
> >
> > +static inline const struct fuse_backing_ops *
> > +fuse_backing_ops_from_map(const struct fuse_backing_map *map)
> > +{
> > +       switch (map->flags & FUSE_BACKING_TYPE_MASK) {
> > +#ifdef CONFIG_FUSE_PASSTHROUGH
> > +       case FUSE_BACKING_TYPE_PASSTHROUGH:
> > +               return &fuse_passthrough_backing_ops;
> > +#endif
> > +       default:
> > +               break;
> > +       }
> > +
> > +       return NULL;
> > +}
> > +
> >  int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
> >  {
> >         struct file *file;
> > -       struct super_block *backing_sb;
> >         struct fuse_backing *fb = NULL;
> > +       const struct fuse_backing_ops *ops = fuse_backing_ops_from_map(map);
> > +       uint32_t op_flags = map->flags & ~FUSE_BACKING_TYPE_MASK;
> >         int res;
> >
> >         pr_debug("%s: fd=%d flags=0x%x\n", __func__, map->fd, map->flags);
> >
> > -       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
> > -       res = -EPERM;
> > -       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
> > +       res = -EOPNOTSUPP;
> > +       if (!ops)
> > +               goto out;
> > +       WARN_ON(ops->type != (map->flags & FUSE_BACKING_TYPE_MASK));
> > +
> > +       res = ops->may_admin ? ops->may_admin(fc, op_flags) : 0;
> > +       if (res)
> >                 goto out;
> >
> >         res = -EINVAL;
> > -       if (map->flags || map->padding)
> > +       if (map->padding)
> >                 goto out;
> >
> >         file = fget_raw(map->fd);
> > @@ -102,14 +124,8 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
> >         if (!file)
> >                 goto out;
> >
> > -       /* read/write/splice/mmap passthrough only relevant for regular files */
> > -       res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
> > -       if (!d_is_reg(file->f_path.dentry))
> > -               goto out_fput;
> > -
> > -       backing_sb = file_inode(file)->i_sb;
> > -       res = -ELOOP;
> > -       if (backing_sb->s_stack_depth >= fc->max_stack_depth)
> > +       res = ops->may_open ? ops->may_open(fc, file) : 0;
> > +       if (res)
> >                 goto out_fput;
> >
> >         fb = kmalloc(sizeof(struct fuse_backing), GFP_KERNEL);
> > @@ -119,14 +135,15 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
> >
> >         fb->file = file;
> >         fb->cred = prepare_creds();
> > +       fb->ops = ops;
> >         refcount_set(&fb->count, 1);
> >
> >         res = fuse_backing_id_alloc(fc, fb);
> >         if (res < 0) {
> >                 fuse_backing_free(fb);
> >                 fb = NULL;
> > +               goto out;
> >         }
> > -
> >  out:
> >         pr_debug("%s: fb=0x%p, ret=%i\n", __func__, fb, res);
> >
> > @@ -137,41 +154,71 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
> >         goto out;
> >  }
> >
> > +static struct fuse_backing *__fuse_backing_lookup(struct fuse_conn *fc,
> > +                                                 int backing_id)
> > +{
> > +       struct fuse_backing *fb;
> > +
> > +       rcu_read_lock();
> > +       fb = idr_find(&fc->backing_files_map, backing_id);
> > +       fb = fuse_backing_get(fb);
> > +       rcu_read_unlock();
> > +
> > +       return fb;
> > +}
> > +
> >  int fuse_backing_close(struct fuse_conn *fc, int backing_id)
> >  {
> > -       struct fuse_backing *fb = NULL;
> > +       struct fuse_backing *fb, *test_fb;
> > +       const struct fuse_backing_ops *ops;
> >         int err;
> >
> >         pr_debug("%s: backing_id=%d\n", __func__, backing_id);
> >
> > -       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
> > -       err = -EPERM;
> > -       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
> > -               goto out;
> > -
> >         err = -EINVAL;
> >         if (backing_id <= 0)
> >                 goto out;
> >
> >         err = -ENOENT;
> > -       fb = fuse_backing_id_remove(fc, backing_id);
> > +       fb = __fuse_backing_lookup(fc, backing_id);
> >         if (!fb)
> >                 goto out;
> > +       ops = fb->ops;
> >
> > -       fuse_backing_put(fb);
> > +       err = ops->may_admin ? ops->may_admin(fc, 0) : 0;
> > +       if (err)
> > +               goto out_fb;
> > +
> > +       err = ops->may_close ? ops->may_close(fc, fb->file) : 0;
> > +       if (err)
> > +               goto out_fb;
> > +
> > +       err = -ENOENT;
> > +       test_fb = fuse_backing_id_remove(fc, backing_id);
> > +       if (!test_fb)
> > +               goto out_fb;
> > +
> > +       WARN_ON(fb != test_fb);
> >         err = 0;
> > +       fuse_backing_put(test_fb);
> > +out_fb:
> > +       fuse_backing_put(fb);
> >  out:
> >         pr_debug("%s: fb=0x%p, err=%i\n", __func__, fb, err);
> >
> >         return err;
> >  }
> >
> > -struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id)
> > +struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
> > +                                        const struct fuse_backing_ops *ops,
> > +                                        int backing_id)
> >  {
> >         struct fuse_backing *fb;
> >
> >         rcu_read_lock();
> >         fb = idr_find(&fc->backing_files_map, backing_id);
> > +       if (fb && fb->ops != ops)
> > +               fb = NULL;
> >         fb = fuse_backing_get(fb);
> >         rcu_read_unlock();
> >
> > diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> > index e5aaf0c668bc11..281bc81f3b448b 100644
> > --- a/fs/fuse/dev.c
> > +++ b/fs/fuse/dev.c
> > @@ -2654,7 +2654,7 @@ static long fuse_dev_ioctl_backing_open(struct file *file,
> >         if (IS_ERR(fud))
> >                 return PTR_ERR(fud);
> >
> > -       if (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
> > +       if (!IS_ENABLED(CONFIG_FUSE_BACKING))
> >                 return -EOPNOTSUPP;
> >
> >         if (copy_from_user(&map, argp, sizeof(map)))
> > @@ -2671,7 +2671,7 @@ static long fuse_dev_ioctl_backing_close(struct file *file, __u32 __user *argp)
> >         if (IS_ERR(fud))
> >                 return PTR_ERR(fud);
> >
> > -       if (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
> > +       if (!IS_ENABLED(CONFIG_FUSE_BACKING))
> >                 return -EOPNOTSUPP;
> >
> >         if (get_user(backing_id, argp))
> > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > index 14c35ce12b87d6..1e7298b2b89b58 100644
> > --- a/fs/fuse/inode.c
> > +++ b/fs/fuse/inode.c
> > @@ -995,7 +995,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
> >         fc->name_max = FUSE_NAME_LOW_MAX;
> >         fc->timeout.req_timeout = 0;
> >
> > -       if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
> > +       if (IS_ENABLED(CONFIG_FUSE_BACKING))
> >                 fuse_backing_files_init(fc);
> >
> >         INIT_LIST_HEAD(&fc->mounts);
> > @@ -1032,7 +1032,7 @@ void fuse_conn_put(struct fuse_conn *fc)
> >                         WARN_ON(atomic_read(&bucket->count) != 1);
> >                         kfree(bucket);
> >                 }
> > -               if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
> > +               if (IS_ENABLED(CONFIG_FUSE_BACKING))
> >                         fuse_backing_files_free(fc);
> >                 call_rcu(&fc->rcu, delayed_release);
> >         }
> > diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c
> > index e0b8d885bc81f3..9792d7b12a775b 100644
> > --- a/fs/fuse/passthrough.c
> > +++ b/fs/fuse/passthrough.c
> > @@ -164,7 +164,7 @@ struct fuse_backing *fuse_passthrough_open(struct file *file,
> >                 goto out;
> >
> >         err = -ENOENT;
> > -       fb = fuse_backing_lookup(fc, backing_id);
> > +       fb = fuse_backing_lookup(fc, &fuse_passthrough_backing_ops, backing_id);
> >         if (!fb)
> >                 goto out;
> >
> > @@ -197,3 +197,38 @@ void fuse_passthrough_release(struct fuse_file *ff, struct fuse_backing *fb)
> >         put_cred(ff->cred);
> >         ff->cred = NULL;
> >  }
> > +
> > +static int fuse_passthrough_may_admin(struct fuse_conn *fc, unsigned int flags)
> > +{
> > +       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
> > +       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
> > +               return -EPERM;
> > +
> > +       if (flags)
> > +               return -EINVAL;
> > +
> > +       return 0;
> > +}
> > +
> > +static int fuse_passthrough_may_open(struct fuse_conn *fc, struct file *file)
> > +{
> > +       struct super_block *backing_sb;
> > +       int res;
> > +
> > +       /* read/write/splice/mmap passthrough only relevant for regular files */
> > +       res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
> > +       if (!d_is_reg(file->f_path.dentry))
> > +               return res;
> > +
> > +       backing_sb = file_inode(file)->i_sb;
> > +       if (backing_sb->s_stack_depth >= fc->max_stack_depth)
> > +               return -ELOOP;
> > +
> > +       return 0;
> > +}
> > +
> > +const struct fuse_backing_ops fuse_passthrough_backing_ops = {
> > +       .type = FUSE_BACKING_TYPE_PASSTHROUGH,
> > +       .may_admin = fuse_passthrough_may_admin,
> > +       .may_open = fuse_passthrough_may_open,
> > +};
> >
> >

Re: [PATCH 1/5] fuse: allow synchronous FUSE_INIT

[Darrick J. Wong]

On Wed, Sep 17, 2025 at 10:22:21AM -0700, Joanne Koong wrote:
> On Mon, Sep 15, 2025 at 5:26 PM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > From: Miklos Szeredi <mszeredi@redhat.com>
> >
> > FUSE_INIT has always been asynchronous with mount.  That means that the
> > server processed this request after the mount syscall returned.
> >
> > This means that FUSE_INIT can't supply the root inode's ID, hence it
> > currently has a hardcoded value.  There are other limitations such as not
> > being able to perform getxattr during mount, which is needed by selinux.
> >
> > To remove these limitations allow server to process FUSE_INIT while
> > initializing the in-core super block for the fuse filesystem.  This can
> > only be done if the server is prepared to handle this, so add
> > FUSE_DEV_IOC_SYNC_INIT ioctl, which
> >
> >  a) lets the server know whether this feature is supported, returning
> >  ENOTTY othewrwise.
> >
> >  b) lets the kernel know to perform a synchronous initialization
> >
> > The implementation is slightly tricky, since fuse_dev/fuse_conn are set up
> > only during super block creation.  This is solved by setting the private
> > data of the fuse device file to a special value ((struct fuse_dev *) 1) and
> > waiting for this to be turned into a proper fuse_dev before commecing with
> > operations on the device file.
> >
> > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> > Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  fs/fuse/fuse_dev_i.h      |   13 +++++++-
> >  fs/fuse/fuse_i.h          |    5 ++-
> >  include/uapi/linux/fuse.h |    1 +
> >  fs/fuse/cuse.c            |    3 +-
> >  fs/fuse/dev.c             |   74 +++++++++++++++++++++++++++++++++------------
> >  fs/fuse/dev_uring.c       |    4 +-
> >  fs/fuse/inode.c           |   50 ++++++++++++++++++++++++------
> >  7 files changed, 115 insertions(+), 35 deletions(-)
> 
> btw, I think an updated version of this has already been merged into
> the fuse for-next tree (commit dfb84c330794)

Thanks for letting me know!

(I don't develop against for-next. ;))

--D

> Thanks,
> Joanne
> 

Re: [PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Darrick J. Wong]

On Wed, Sep 17, 2025 at 05:09:14AM +0200, Amir Goldstein wrote:
> On Tue, Sep 16, 2025 at 2:30 AM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > From: Darrick J. Wong <djwong@kernel.org>
> >
> > Enable the use of the backing file open/close ioctls so that fuse
> > servers can register block devices for use with iomap.
> >
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  fs/fuse/fuse_i.h          |    5 ++
> >  include/uapi/linux/fuse.h |    3 +
> >  fs/fuse/Kconfig           |    1
> >  fs/fuse/backing.c         |   12 +++++
> >  fs/fuse/file_iomap.c      |   99 +++++++++++++++++++++++++++++++++++++++++----
> >  fs/fuse/trace.c           |    1
> >  6 files changed, 111 insertions(+), 10 deletions(-)
> >
> >
> > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > index 389b123f0bf144..791f210c13a876 100644
> > --- a/fs/fuse/fuse_i.h
> > +++ b/fs/fuse/fuse_i.h
> > @@ -97,12 +97,14 @@ struct fuse_submount_lookup {
> >  };
> >
> >  struct fuse_conn;
> > +struct fuse_backing;
> >
> >  /** Operations for subsystems that want to use a backing file */
> >  struct fuse_backing_ops {
> >         int (*may_admin)(struct fuse_conn *fc, uint32_t flags);
> >         int (*may_open)(struct fuse_conn *fc, struct file *file);
> >         int (*may_close)(struct fuse_conn *fc, struct file *file);
> > +       int (*post_open)(struct fuse_conn *fc, struct fuse_backing *fb);
> >         unsigned int type;
> >  };
> >
> > @@ -110,6 +112,7 @@ struct fuse_backing_ops {
> >  struct fuse_backing {
> >         struct file *file;
> >         struct cred *cred;
> > +       struct block_device *bdev;
> >         const struct fuse_backing_ops *ops;
> >
> >         /** refcount */
> > @@ -1704,6 +1707,8 @@ static inline bool fuse_has_iomap(const struct inode *inode)
> >  {
> >         return get_fuse_conn_c(inode)->iomap;
> >  }
> > +
> > +extern const struct fuse_backing_ops fuse_iomap_backing_ops;
> >  #else
> >  # define fuse_iomap_enabled(...)               (false)
> >  # define fuse_has_iomap(...)                   (false)
> > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > index 3634cbe602cd9c..3a367f387795ff 100644
> > --- a/include/uapi/linux/fuse.h
> > +++ b/include/uapi/linux/fuse.h
> > @@ -1124,7 +1124,8 @@ struct fuse_notify_retrieve_in {
> >
> >  #define FUSE_BACKING_TYPE_MASK         (0xFF)
> >  #define FUSE_BACKING_TYPE_PASSTHROUGH  (0)
> > -#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_PASSTHROUGH)
> > +#define FUSE_BACKING_TYPE_IOMAP                (1)
> > +#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_IOMAP)
> >
> >  #define FUSE_BACKING_FLAGS_ALL         (FUSE_BACKING_TYPE_MASK)
> >
> > diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> > index 52e1a04183e760..baa38cf0f295ff 100644
> > --- a/fs/fuse/Kconfig
> > +++ b/fs/fuse/Kconfig
> > @@ -75,6 +75,7 @@ config FUSE_IOMAP
> >         depends on FUSE_FS
> >         depends on BLOCK
> >         select FS_IOMAP
> > +       select FUSE_BACKING
> >         help
> >           Enable fuse servers to operate the regular file I/O path through
> >           the fs-iomap library in the kernel.  This enables higher performance
> > diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
> > index 229c101ab46b0e..fc58636ac78eaa 100644
> > --- a/fs/fuse/backing.c
> > +++ b/fs/fuse/backing.c
> > @@ -89,6 +89,10 @@ fuse_backing_ops_from_map(const struct fuse_backing_map *map)
> >  #ifdef CONFIG_FUSE_PASSTHROUGH
> >         case FUSE_BACKING_TYPE_PASSTHROUGH:
> >                 return &fuse_passthrough_backing_ops;
> > +#endif
> > +#ifdef CONFIG_FUSE_IOMAP
> > +       case FUSE_BACKING_TYPE_IOMAP:
> > +               return &fuse_iomap_backing_ops;
> >  #endif
> >         default:
> >                 break;
> > @@ -137,8 +141,16 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
> >         fb->file = file;
> >         fb->cred = prepare_creds();
> >         fb->ops = ops;
> > +       fb->bdev = NULL;
> >         refcount_set(&fb->count, 1);
> >
> > +       res = ops->post_open ? ops->post_open(fc, fb) : 0;
> > +       if (res) {
> > +               fuse_backing_free(fb);
> > +               fb = NULL;
> > +               goto out;
> > +       }
> > +
> >         res = fuse_backing_id_alloc(fc, fb);
> >         if (res < 0) {
> >                 fuse_backing_free(fb);
> > diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> > index e7d19e2aee4541..3a4161633add0e 100644
> > --- a/fs/fuse/file_iomap.c
> > +++ b/fs/fuse/file_iomap.c
> > @@ -319,10 +319,6 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
> >                 return false;
> >         }
> >
> > -       /* XXX: we don't support devices yet */
> > -       if (BAD_DATA(map->dev != FUSE_IOMAP_DEV_NULL))
> > -               return false;
> > -
> >         /* No overflows in the device range, if supplied */
> >         if (map->addr != FUSE_IOMAP_NULL_ADDR &&
> >             BAD_DATA(check_add_overflow(map->addr, map->length, &end)))
> > @@ -334,6 +330,7 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
> >  /* Convert a mapping from the server into something the kernel can use */
> >  static inline void fuse_iomap_from_server(struct inode *inode,
> >                                           struct iomap *iomap,
> > +                                         const struct fuse_backing *fb,
> >                                           const struct fuse_iomap_io *fmap)
> >  {
> >         iomap->addr = fmap->addr;
> > @@ -341,7 +338,9 @@ static inline void fuse_iomap_from_server(struct inode *inode,
> >         iomap->length = fmap->length;
> >         iomap->type = fuse_iomap_type_from_server(fmap->type);
> >         iomap->flags = fuse_iomap_flags_from_server(fmap->flags);
> > -       iomap->bdev = inode->i_sb->s_bdev; /* XXX */
> > +
> > +       iomap->bdev = fb ? fb->bdev : NULL;
> > +       iomap->dax_dev = NULL;
> >  }
> >
> >  /* Convert a mapping from the kernel into something the server can use */
> > @@ -392,6 +391,27 @@ static inline bool fuse_is_iomap_file_write(unsigned int opflags)
> >         return opflags & (IOMAP_WRITE | IOMAP_ZERO | IOMAP_UNSHARE);
> >  }
> >
> > +static inline struct fuse_backing *
> > +fuse_iomap_find_dev(struct fuse_conn *fc, const struct fuse_iomap_io *map)
> > +{
> > +       struct fuse_backing *ret = NULL;
> > +
> > +       if (map->dev != FUSE_IOMAP_DEV_NULL && map->dev < INT_MAX)
> > +               ret = fuse_backing_lookup(fc, &fuse_iomap_backing_ops,
> > +                                         map->dev);
> > +
> > +       switch (map->type) {
> > +       case FUSE_IOMAP_TYPE_MAPPED:
> > +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> > +               /* Mappings backed by space must have a device/addr */
> > +               if (BAD_DATA(ret == NULL))
> > +                       return ERR_PTR(-EFSCORRUPTED);
> > +               break;
> > +       }
> > +
> > +       return ret;
> > +}
> > +
> >  static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> >                             unsigned opflags, struct iomap *iomap,
> >                             struct iomap *srcmap)
> > @@ -405,6 +425,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> >         };
> >         struct fuse_iomap_begin_out outarg = { };
> >         struct fuse_mount *fm = get_fuse_mount(inode);
> > +       struct fuse_backing *read_dev = NULL;
> > +       struct fuse_backing *write_dev = NULL;
> >         FUSE_ARGS(args);
> >         int err;
> >
> > @@ -431,24 +453,44 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> >         if (err)
> >                 return err;
> >
> > +       read_dev = fuse_iomap_find_dev(fm->fc, &outarg.read);
> > +       if (IS_ERR(read_dev))
> > +               return PTR_ERR(read_dev);
> > +
> >         if (fuse_is_iomap_file_write(opflags) &&
> >             outarg.write.type != FUSE_IOMAP_TYPE_PURE_OVERWRITE) {
> > +               /* open the write device */
> > +               write_dev = fuse_iomap_find_dev(fm->fc, &outarg.write);
> > +               if (IS_ERR(write_dev)) {
> > +                       err = PTR_ERR(write_dev);
> > +                       goto out_read_dev;
> > +               }
> > +
> >                 /*
> >                  * For an out of place write, we must supply the write mapping
> >                  * via @iomap, and the read mapping via @srcmap.
> >                  */
> > -               fuse_iomap_from_server(inode, iomap, &outarg.write);
> > -               fuse_iomap_from_server(inode, srcmap, &outarg.read);
> > +               fuse_iomap_from_server(inode, iomap, write_dev, &outarg.write);
> > +               fuse_iomap_from_server(inode, srcmap, read_dev, &outarg.read);
> >         } else {
> >                 /*
> >                  * For everything else (reads, reporting, and pure overwrites),
> >                  * we can return the sole mapping through @iomap and leave
> >                  * @srcmap unchanged from its default (HOLE).
> >                  */
> > -               fuse_iomap_from_server(inode, iomap, &outarg.read);
> > +               fuse_iomap_from_server(inode, iomap, read_dev, &outarg.read);
> >         }
> >
> > -       return 0;
> > +       /*
> > +        * XXX: if we ever want to support closing devices, we need a way to
> > +        * track the fuse_backing refcount all the way through bio endios.
> > +        * For now we put the refcount here because you can't remove an iomap
> > +        * device until unmount time.
> > +        */
> > +       fuse_backing_put(write_dev);
> > +out_read_dev:
> > +       fuse_backing_put(read_dev);
> > +       return err;
> >  }
> >
> >  /* Decide if we send FUSE_IOMAP_END to the fuse server */
> > @@ -523,3 +565,42 @@ const struct iomap_ops fuse_iomap_ops = {
> >         .iomap_begin            = fuse_iomap_begin,
> >         .iomap_end              = fuse_iomap_end,
> >  };
> > +
> > +static int fuse_iomap_may_admin(struct fuse_conn *fc, unsigned int flags)
> > +{
> > +       if (!fc->iomap)
> > +               return -EPERM;
> > +
> 
> IIRC, on RFC I asked why is iomap exempt from CAP_SYS_ADMIN
> check. If there was a good reason, I forgot it.

CAP_SYS_ADMIN means that the fuse server (or the fuservicemount helper)
can make quite a lot of other changes to the system that are not at all
related to being a filesystem.  I'd rather not use that one.

Instead I require CAP_SYS_RAWIO to enable fc->iomap, so that the fuse
server has to have *some* privilege, but only enough to write to raw
block devices since that's what iomap does.

> The problem is that while fuse-iomap fs is only expected to open
> a handful of backing devs, we would like to prevent abuse of this ioctl
> by a buggy or malicious user.
> 
> I think that if you want to avoid CAP_SYS_ADMIN here you should
> enforce a limit on the number of backing bdevs.
> 
> If you accept my suggestion to mutually exclude passthrough and
> iomap features per fs, then you'd just need to keep track on numbers
> of fuse_backing ids and place a limit for iomap fs.
> 
> BTW, I think it is enough keep track of the number of backing ids
> and no need to keep track of the number of fuse_backing objects
> (which can outlive a backing id), because an "anonymous" fuse_backing
> object is always associated with an open fuse file - that's the same as
> an overlayfs backing file, which is not accounted for in ulimit.

How about restricting the backing ids to RLIMIT_NOFILE?  The @end param
to idr_alloc_cyclic constrains them in exactly that way.

--D

> Thanks,
> Amir.
> 

Re: [PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Amir Goldstein]

On Thu, Sep 18, 2025 at 8:17 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Wed, Sep 17, 2025 at 05:09:14AM +0200, Amir Goldstein wrote:
> > On Tue, Sep 16, 2025 at 2:30 AM Darrick J. Wong <djwong@kernel.org> wrote:
> > >
> > > From: Darrick J. Wong <djwong@kernel.org>
> > >
> > > Enable the use of the backing file open/close ioctls so that fuse
> > > servers can register block devices for use with iomap.
> > >
> > > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > > ---
> > >  fs/fuse/fuse_i.h          |    5 ++
> > >  include/uapi/linux/fuse.h |    3 +
> > >  fs/fuse/Kconfig           |    1
> > >  fs/fuse/backing.c         |   12 +++++
> > >  fs/fuse/file_iomap.c      |   99 +++++++++++++++++++++++++++++++++++++++++----
> > >  fs/fuse/trace.c           |    1
> > >  6 files changed, 111 insertions(+), 10 deletions(-)
> > >
> > >
> > > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > > index 389b123f0bf144..791f210c13a876 100644
> > > --- a/fs/fuse/fuse_i.h
> > > +++ b/fs/fuse/fuse_i.h
> > > @@ -97,12 +97,14 @@ struct fuse_submount_lookup {
> > >  };
> > >
> > >  struct fuse_conn;
> > > +struct fuse_backing;
> > >
> > >  /** Operations for subsystems that want to use a backing file */
> > >  struct fuse_backing_ops {
> > >         int (*may_admin)(struct fuse_conn *fc, uint32_t flags);
> > >         int (*may_open)(struct fuse_conn *fc, struct file *file);
> > >         int (*may_close)(struct fuse_conn *fc, struct file *file);
> > > +       int (*post_open)(struct fuse_conn *fc, struct fuse_backing *fb);
> > >         unsigned int type;
> > >  };
> > >
> > > @@ -110,6 +112,7 @@ struct fuse_backing_ops {
> > >  struct fuse_backing {
> > >         struct file *file;
> > >         struct cred *cred;
> > > +       struct block_device *bdev;
> > >         const struct fuse_backing_ops *ops;
> > >
> > >         /** refcount */
> > > @@ -1704,6 +1707,8 @@ static inline bool fuse_has_iomap(const struct inode *inode)
> > >  {
> > >         return get_fuse_conn_c(inode)->iomap;
> > >  }
> > > +
> > > +extern const struct fuse_backing_ops fuse_iomap_backing_ops;
> > >  #else
> > >  # define fuse_iomap_enabled(...)               (false)
> > >  # define fuse_has_iomap(...)                   (false)
> > > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > > index 3634cbe602cd9c..3a367f387795ff 100644
> > > --- a/include/uapi/linux/fuse.h
> > > +++ b/include/uapi/linux/fuse.h
> > > @@ -1124,7 +1124,8 @@ struct fuse_notify_retrieve_in {
> > >
> > >  #define FUSE_BACKING_TYPE_MASK         (0xFF)
> > >  #define FUSE_BACKING_TYPE_PASSTHROUGH  (0)
> > > -#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_PASSTHROUGH)
> > > +#define FUSE_BACKING_TYPE_IOMAP                (1)
> > > +#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_IOMAP)
> > >
> > >  #define FUSE_BACKING_FLAGS_ALL         (FUSE_BACKING_TYPE_MASK)
> > >
> > > diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> > > index 52e1a04183e760..baa38cf0f295ff 100644
> > > --- a/fs/fuse/Kconfig
> > > +++ b/fs/fuse/Kconfig
> > > @@ -75,6 +75,7 @@ config FUSE_IOMAP
> > >         depends on FUSE_FS
> > >         depends on BLOCK
> > >         select FS_IOMAP
> > > +       select FUSE_BACKING
> > >         help
> > >           Enable fuse servers to operate the regular file I/O path through
> > >           the fs-iomap library in the kernel.  This enables higher performance
> > > diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
> > > index 229c101ab46b0e..fc58636ac78eaa 100644
> > > --- a/fs/fuse/backing.c
> > > +++ b/fs/fuse/backing.c
> > > @@ -89,6 +89,10 @@ fuse_backing_ops_from_map(const struct fuse_backing_map *map)
> > >  #ifdef CONFIG_FUSE_PASSTHROUGH
> > >         case FUSE_BACKING_TYPE_PASSTHROUGH:
> > >                 return &fuse_passthrough_backing_ops;
> > > +#endif
> > > +#ifdef CONFIG_FUSE_IOMAP
> > > +       case FUSE_BACKING_TYPE_IOMAP:
> > > +               return &fuse_iomap_backing_ops;
> > >  #endif
> > >         default:
> > >                 break;
> > > @@ -137,8 +141,16 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
> > >         fb->file = file;
> > >         fb->cred = prepare_creds();
> > >         fb->ops = ops;
> > > +       fb->bdev = NULL;
> > >         refcount_set(&fb->count, 1);
> > >
> > > +       res = ops->post_open ? ops->post_open(fc, fb) : 0;
> > > +       if (res) {
> > > +               fuse_backing_free(fb);
> > > +               fb = NULL;
> > > +               goto out;
> > > +       }
> > > +
> > >         res = fuse_backing_id_alloc(fc, fb);
> > >         if (res < 0) {
> > >                 fuse_backing_free(fb);
> > > diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> > > index e7d19e2aee4541..3a4161633add0e 100644
> > > --- a/fs/fuse/file_iomap.c
> > > +++ b/fs/fuse/file_iomap.c
> > > @@ -319,10 +319,6 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
> > >                 return false;
> > >         }
> > >
> > > -       /* XXX: we don't support devices yet */
> > > -       if (BAD_DATA(map->dev != FUSE_IOMAP_DEV_NULL))
> > > -               return false;
> > > -
> > >         /* No overflows in the device range, if supplied */
> > >         if (map->addr != FUSE_IOMAP_NULL_ADDR &&
> > >             BAD_DATA(check_add_overflow(map->addr, map->length, &end)))
> > > @@ -334,6 +330,7 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
> > >  /* Convert a mapping from the server into something the kernel can use */
> > >  static inline void fuse_iomap_from_server(struct inode *inode,
> > >                                           struct iomap *iomap,
> > > +                                         const struct fuse_backing *fb,
> > >                                           const struct fuse_iomap_io *fmap)
> > >  {
> > >         iomap->addr = fmap->addr;
> > > @@ -341,7 +338,9 @@ static inline void fuse_iomap_from_server(struct inode *inode,
> > >         iomap->length = fmap->length;
> > >         iomap->type = fuse_iomap_type_from_server(fmap->type);
> > >         iomap->flags = fuse_iomap_flags_from_server(fmap->flags);
> > > -       iomap->bdev = inode->i_sb->s_bdev; /* XXX */
> > > +
> > > +       iomap->bdev = fb ? fb->bdev : NULL;
> > > +       iomap->dax_dev = NULL;
> > >  }
> > >
> > >  /* Convert a mapping from the kernel into something the server can use */
> > > @@ -392,6 +391,27 @@ static inline bool fuse_is_iomap_file_write(unsigned int opflags)
> > >         return opflags & (IOMAP_WRITE | IOMAP_ZERO | IOMAP_UNSHARE);
> > >  }
> > >
> > > +static inline struct fuse_backing *
> > > +fuse_iomap_find_dev(struct fuse_conn *fc, const struct fuse_iomap_io *map)
> > > +{
> > > +       struct fuse_backing *ret = NULL;
> > > +
> > > +       if (map->dev != FUSE_IOMAP_DEV_NULL && map->dev < INT_MAX)
> > > +               ret = fuse_backing_lookup(fc, &fuse_iomap_backing_ops,
> > > +                                         map->dev);
> > > +
> > > +       switch (map->type) {
> > > +       case FUSE_IOMAP_TYPE_MAPPED:
> > > +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> > > +               /* Mappings backed by space must have a device/addr */
> > > +               if (BAD_DATA(ret == NULL))
> > > +                       return ERR_PTR(-EFSCORRUPTED);
> > > +               break;
> > > +       }
> > > +
> > > +       return ret;
> > > +}
> > > +
> > >  static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> > >                             unsigned opflags, struct iomap *iomap,
> > >                             struct iomap *srcmap)
> > > @@ -405,6 +425,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> > >         };
> > >         struct fuse_iomap_begin_out outarg = { };
> > >         struct fuse_mount *fm = get_fuse_mount(inode);
> > > +       struct fuse_backing *read_dev = NULL;
> > > +       struct fuse_backing *write_dev = NULL;
> > >         FUSE_ARGS(args);
> > >         int err;
> > >
> > > @@ -431,24 +453,44 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> > >         if (err)
> > >                 return err;
> > >
> > > +       read_dev = fuse_iomap_find_dev(fm->fc, &outarg.read);
> > > +       if (IS_ERR(read_dev))
> > > +               return PTR_ERR(read_dev);
> > > +
> > >         if (fuse_is_iomap_file_write(opflags) &&
> > >             outarg.write.type != FUSE_IOMAP_TYPE_PURE_OVERWRITE) {
> > > +               /* open the write device */
> > > +               write_dev = fuse_iomap_find_dev(fm->fc, &outarg.write);
> > > +               if (IS_ERR(write_dev)) {
> > > +                       err = PTR_ERR(write_dev);
> > > +                       goto out_read_dev;
> > > +               }
> > > +
> > >                 /*
> > >                  * For an out of place write, we must supply the write mapping
> > >                  * via @iomap, and the read mapping via @srcmap.
> > >                  */
> > > -               fuse_iomap_from_server(inode, iomap, &outarg.write);
> > > -               fuse_iomap_from_server(inode, srcmap, &outarg.read);
> > > +               fuse_iomap_from_server(inode, iomap, write_dev, &outarg.write);
> > > +               fuse_iomap_from_server(inode, srcmap, read_dev, &outarg.read);
> > >         } else {
> > >                 /*
> > >                  * For everything else (reads, reporting, and pure overwrites),
> > >                  * we can return the sole mapping through @iomap and leave
> > >                  * @srcmap unchanged from its default (HOLE).
> > >                  */
> > > -               fuse_iomap_from_server(inode, iomap, &outarg.read);
> > > +               fuse_iomap_from_server(inode, iomap, read_dev, &outarg.read);
> > >         }
> > >
> > > -       return 0;
> > > +       /*
> > > +        * XXX: if we ever want to support closing devices, we need a way to
> > > +        * track the fuse_backing refcount all the way through bio endios.
> > > +        * For now we put the refcount here because you can't remove an iomap
> > > +        * device until unmount time.
> > > +        */
> > > +       fuse_backing_put(write_dev);
> > > +out_read_dev:
> > > +       fuse_backing_put(read_dev);
> > > +       return err;
> > >  }
> > >
> > >  /* Decide if we send FUSE_IOMAP_END to the fuse server */
> > > @@ -523,3 +565,42 @@ const struct iomap_ops fuse_iomap_ops = {
> > >         .iomap_begin            = fuse_iomap_begin,
> > >         .iomap_end              = fuse_iomap_end,
> > >  };
> > > +
> > > +static int fuse_iomap_may_admin(struct fuse_conn *fc, unsigned int flags)
> > > +{
> > > +       if (!fc->iomap)
> > > +               return -EPERM;
> > > +
> >
> > IIRC, on RFC I asked why is iomap exempt from CAP_SYS_ADMIN
> > check. If there was a good reason, I forgot it.
>
> CAP_SYS_ADMIN means that the fuse server (or the fuservicemount helper)
> can make quite a lot of other changes to the system that are not at all
> related to being a filesystem.  I'd rather not use that one.
>
> Instead I require CAP_SYS_RAWIO to enable fc->iomap, so that the fuse
> server has to have *some* privilege, but only enough to write to raw
> block devices since that's what iomap does.
>
> > The problem is that while fuse-iomap fs is only expected to open
> > a handful of backing devs, we would like to prevent abuse of this ioctl
> > by a buggy or malicious user.
> >
> > I think that if you want to avoid CAP_SYS_ADMIN here you should
> > enforce a limit on the number of backing bdevs.
> >
> > If you accept my suggestion to mutually exclude passthrough and
> > iomap features per fs, then you'd just need to keep track on numbers
> > of fuse_backing ids and place a limit for iomap fs.
> >
> > BTW, I think it is enough keep track of the number of backing ids
> > and no need to keep track of the number of fuse_backing objects
> > (which can outlive a backing id), because an "anonymous" fuse_backing
> > object is always associated with an open fuse file - that's the same as
> > an overlayfs backing file, which is not accounted for in ulimit.
>
> How about restricting the backing ids to RLIMIT_NOFILE?  The @end param
> to idr_alloc_cyclic constrains them in exactly that way.

IDK. My impression was that Miklos didn't like having a large number
of unaccounted files, but it's up to him.

Do you have an estimate on the worst case number of backing blockdev
for fuse iomap?

Thanks,
Amir.

Re: [PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Darrick J. Wong]

On Thu, Sep 18, 2025 at 08:42:08PM +0200, Amir Goldstein wrote:
> On Thu, Sep 18, 2025 at 8:17 PM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > On Wed, Sep 17, 2025 at 05:09:14AM +0200, Amir Goldstein wrote:
> > > On Tue, Sep 16, 2025 at 2:30 AM Darrick J. Wong <djwong@kernel.org> wrote:
> > > >
> > > > From: Darrick J. Wong <djwong@kernel.org>
> > > >
> > > > Enable the use of the backing file open/close ioctls so that fuse
> > > > servers can register block devices for use with iomap.
> > > >
> > > > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > > > ---
> > > >  fs/fuse/fuse_i.h          |    5 ++
> > > >  include/uapi/linux/fuse.h |    3 +
> > > >  fs/fuse/Kconfig           |    1
> > > >  fs/fuse/backing.c         |   12 +++++
> > > >  fs/fuse/file_iomap.c      |   99 +++++++++++++++++++++++++++++++++++++++++----
> > > >  fs/fuse/trace.c           |    1
> > > >  6 files changed, 111 insertions(+), 10 deletions(-)
> > > >
> > > >
> > > > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > > > index 389b123f0bf144..791f210c13a876 100644
> > > > --- a/fs/fuse/fuse_i.h
> > > > +++ b/fs/fuse/fuse_i.h
> > > > @@ -97,12 +97,14 @@ struct fuse_submount_lookup {
> > > >  };
> > > >
> > > >  struct fuse_conn;
> > > > +struct fuse_backing;
> > > >
> > > >  /** Operations for subsystems that want to use a backing file */
> > > >  struct fuse_backing_ops {
> > > >         int (*may_admin)(struct fuse_conn *fc, uint32_t flags);
> > > >         int (*may_open)(struct fuse_conn *fc, struct file *file);
> > > >         int (*may_close)(struct fuse_conn *fc, struct file *file);
> > > > +       int (*post_open)(struct fuse_conn *fc, struct fuse_backing *fb);
> > > >         unsigned int type;
> > > >  };
> > > >
> > > > @@ -110,6 +112,7 @@ struct fuse_backing_ops {
> > > >  struct fuse_backing {
> > > >         struct file *file;
> > > >         struct cred *cred;
> > > > +       struct block_device *bdev;
> > > >         const struct fuse_backing_ops *ops;
> > > >
> > > >         /** refcount */
> > > > @@ -1704,6 +1707,8 @@ static inline bool fuse_has_iomap(const struct inode *inode)
> > > >  {
> > > >         return get_fuse_conn_c(inode)->iomap;
> > > >  }
> > > > +
> > > > +extern const struct fuse_backing_ops fuse_iomap_backing_ops;
> > > >  #else
> > > >  # define fuse_iomap_enabled(...)               (false)
> > > >  # define fuse_has_iomap(...)                   (false)
> > > > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > > > index 3634cbe602cd9c..3a367f387795ff 100644
> > > > --- a/include/uapi/linux/fuse.h
> > > > +++ b/include/uapi/linux/fuse.h
> > > > @@ -1124,7 +1124,8 @@ struct fuse_notify_retrieve_in {
> > > >
> > > >  #define FUSE_BACKING_TYPE_MASK         (0xFF)
> > > >  #define FUSE_BACKING_TYPE_PASSTHROUGH  (0)
> > > > -#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_PASSTHROUGH)
> > > > +#define FUSE_BACKING_TYPE_IOMAP                (1)
> > > > +#define FUSE_BACKING_MAX_TYPE          (FUSE_BACKING_TYPE_IOMAP)
> > > >
> > > >  #define FUSE_BACKING_FLAGS_ALL         (FUSE_BACKING_TYPE_MASK)
> > > >
> > > > diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> > > > index 52e1a04183e760..baa38cf0f295ff 100644
> > > > --- a/fs/fuse/Kconfig
> > > > +++ b/fs/fuse/Kconfig
> > > > @@ -75,6 +75,7 @@ config FUSE_IOMAP
> > > >         depends on FUSE_FS
> > > >         depends on BLOCK
> > > >         select FS_IOMAP
> > > > +       select FUSE_BACKING
> > > >         help
> > > >           Enable fuse servers to operate the regular file I/O path through
> > > >           the fs-iomap library in the kernel.  This enables higher performance
> > > > diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
> > > > index 229c101ab46b0e..fc58636ac78eaa 100644
> > > > --- a/fs/fuse/backing.c
> > > > +++ b/fs/fuse/backing.c
> > > > @@ -89,6 +89,10 @@ fuse_backing_ops_from_map(const struct fuse_backing_map *map)
> > > >  #ifdef CONFIG_FUSE_PASSTHROUGH
> > > >         case FUSE_BACKING_TYPE_PASSTHROUGH:
> > > >                 return &fuse_passthrough_backing_ops;
> > > > +#endif
> > > > +#ifdef CONFIG_FUSE_IOMAP
> > > > +       case FUSE_BACKING_TYPE_IOMAP:
> > > > +               return &fuse_iomap_backing_ops;
> > > >  #endif
> > > >         default:
> > > >                 break;
> > > > @@ -137,8 +141,16 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
> > > >         fb->file = file;
> > > >         fb->cred = prepare_creds();
> > > >         fb->ops = ops;
> > > > +       fb->bdev = NULL;
> > > >         refcount_set(&fb->count, 1);
> > > >
> > > > +       res = ops->post_open ? ops->post_open(fc, fb) : 0;
> > > > +       if (res) {
> > > > +               fuse_backing_free(fb);
> > > > +               fb = NULL;
> > > > +               goto out;
> > > > +       }
> > > > +
> > > >         res = fuse_backing_id_alloc(fc, fb);
> > > >         if (res < 0) {
> > > >                 fuse_backing_free(fb);
> > > > diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> > > > index e7d19e2aee4541..3a4161633add0e 100644
> > > > --- a/fs/fuse/file_iomap.c
> > > > +++ b/fs/fuse/file_iomap.c
> > > > @@ -319,10 +319,6 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
> > > >                 return false;
> > > >         }
> > > >
> > > > -       /* XXX: we don't support devices yet */
> > > > -       if (BAD_DATA(map->dev != FUSE_IOMAP_DEV_NULL))
> > > > -               return false;
> > > > -
> > > >         /* No overflows in the device range, if supplied */
> > > >         if (map->addr != FUSE_IOMAP_NULL_ADDR &&
> > > >             BAD_DATA(check_add_overflow(map->addr, map->length, &end)))
> > > > @@ -334,6 +330,7 @@ static inline bool fuse_iomap_check_mapping(const struct inode *inode,
> > > >  /* Convert a mapping from the server into something the kernel can use */
> > > >  static inline void fuse_iomap_from_server(struct inode *inode,
> > > >                                           struct iomap *iomap,
> > > > +                                         const struct fuse_backing *fb,
> > > >                                           const struct fuse_iomap_io *fmap)
> > > >  {
> > > >         iomap->addr = fmap->addr;
> > > > @@ -341,7 +338,9 @@ static inline void fuse_iomap_from_server(struct inode *inode,
> > > >         iomap->length = fmap->length;
> > > >         iomap->type = fuse_iomap_type_from_server(fmap->type);
> > > >         iomap->flags = fuse_iomap_flags_from_server(fmap->flags);
> > > > -       iomap->bdev = inode->i_sb->s_bdev; /* XXX */
> > > > +
> > > > +       iomap->bdev = fb ? fb->bdev : NULL;
> > > > +       iomap->dax_dev = NULL;
> > > >  }
> > > >
> > > >  /* Convert a mapping from the kernel into something the server can use */
> > > > @@ -392,6 +391,27 @@ static inline bool fuse_is_iomap_file_write(unsigned int opflags)
> > > >         return opflags & (IOMAP_WRITE | IOMAP_ZERO | IOMAP_UNSHARE);
> > > >  }
> > > >
> > > > +static inline struct fuse_backing *
> > > > +fuse_iomap_find_dev(struct fuse_conn *fc, const struct fuse_iomap_io *map)
> > > > +{
> > > > +       struct fuse_backing *ret = NULL;
> > > > +
> > > > +       if (map->dev != FUSE_IOMAP_DEV_NULL && map->dev < INT_MAX)
> > > > +               ret = fuse_backing_lookup(fc, &fuse_iomap_backing_ops,
> > > > +                                         map->dev);
> > > > +
> > > > +       switch (map->type) {
> > > > +       case FUSE_IOMAP_TYPE_MAPPED:
> > > > +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> > > > +               /* Mappings backed by space must have a device/addr */
> > > > +               if (BAD_DATA(ret == NULL))
> > > > +                       return ERR_PTR(-EFSCORRUPTED);
> > > > +               break;
> > > > +       }
> > > > +
> > > > +       return ret;
> > > > +}
> > > > +
> > > >  static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> > > >                             unsigned opflags, struct iomap *iomap,
> > > >                             struct iomap *srcmap)
> > > > @@ -405,6 +425,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> > > >         };
> > > >         struct fuse_iomap_begin_out outarg = { };
> > > >         struct fuse_mount *fm = get_fuse_mount(inode);
> > > > +       struct fuse_backing *read_dev = NULL;
> > > > +       struct fuse_backing *write_dev = NULL;
> > > >         FUSE_ARGS(args);
> > > >         int err;
> > > >
> > > > @@ -431,24 +453,44 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t count,
> > > >         if (err)
> > > >                 return err;
> > > >
> > > > +       read_dev = fuse_iomap_find_dev(fm->fc, &outarg.read);
> > > > +       if (IS_ERR(read_dev))
> > > > +               return PTR_ERR(read_dev);
> > > > +
> > > >         if (fuse_is_iomap_file_write(opflags) &&
> > > >             outarg.write.type != FUSE_IOMAP_TYPE_PURE_OVERWRITE) {
> > > > +               /* open the write device */
> > > > +               write_dev = fuse_iomap_find_dev(fm->fc, &outarg.write);
> > > > +               if (IS_ERR(write_dev)) {
> > > > +                       err = PTR_ERR(write_dev);
> > > > +                       goto out_read_dev;
> > > > +               }
> > > > +
> > > >                 /*
> > > >                  * For an out of place write, we must supply the write mapping
> > > >                  * via @iomap, and the read mapping via @srcmap.
> > > >                  */
> > > > -               fuse_iomap_from_server(inode, iomap, &outarg.write);
> > > > -               fuse_iomap_from_server(inode, srcmap, &outarg.read);
> > > > +               fuse_iomap_from_server(inode, iomap, write_dev, &outarg.write);
> > > > +               fuse_iomap_from_server(inode, srcmap, read_dev, &outarg.read);
> > > >         } else {
> > > >                 /*
> > > >                  * For everything else (reads, reporting, and pure overwrites),
> > > >                  * we can return the sole mapping through @iomap and leave
> > > >                  * @srcmap unchanged from its default (HOLE).
> > > >                  */
> > > > -               fuse_iomap_from_server(inode, iomap, &outarg.read);
> > > > +               fuse_iomap_from_server(inode, iomap, read_dev, &outarg.read);
> > > >         }
> > > >
> > > > -       return 0;
> > > > +       /*
> > > > +        * XXX: if we ever want to support closing devices, we need a way to
> > > > +        * track the fuse_backing refcount all the way through bio endios.
> > > > +        * For now we put the refcount here because you can't remove an iomap
> > > > +        * device until unmount time.
> > > > +        */
> > > > +       fuse_backing_put(write_dev);
> > > > +out_read_dev:
> > > > +       fuse_backing_put(read_dev);
> > > > +       return err;
> > > >  }
> > > >
> > > >  /* Decide if we send FUSE_IOMAP_END to the fuse server */
> > > > @@ -523,3 +565,42 @@ const struct iomap_ops fuse_iomap_ops = {
> > > >         .iomap_begin            = fuse_iomap_begin,
> > > >         .iomap_end              = fuse_iomap_end,
> > > >  };
> > > > +
> > > > +static int fuse_iomap_may_admin(struct fuse_conn *fc, unsigned int flags)
> > > > +{
> > > > +       if (!fc->iomap)
> > > > +               return -EPERM;
> > > > +
> > >
> > > IIRC, on RFC I asked why is iomap exempt from CAP_SYS_ADMIN
> > > check. If there was a good reason, I forgot it.
> >
> > CAP_SYS_ADMIN means that the fuse server (or the fuservicemount helper)
> > can make quite a lot of other changes to the system that are not at all
> > related to being a filesystem.  I'd rather not use that one.
> >
> > Instead I require CAP_SYS_RAWIO to enable fc->iomap, so that the fuse
> > server has to have *some* privilege, but only enough to write to raw
> > block devices since that's what iomap does.
> >
> > > The problem is that while fuse-iomap fs is only expected to open
> > > a handful of backing devs, we would like to prevent abuse of this ioctl
> > > by a buggy or malicious user.
> > >
> > > I think that if you want to avoid CAP_SYS_ADMIN here you should
> > > enforce a limit on the number of backing bdevs.
> > >
> > > If you accept my suggestion to mutually exclude passthrough and
> > > iomap features per fs, then you'd just need to keep track on numbers
> > > of fuse_backing ids and place a limit for iomap fs.
> > >
> > > BTW, I think it is enough keep track of the number of backing ids
> > > and no need to keep track of the number of fuse_backing objects
> > > (which can outlive a backing id), because an "anonymous" fuse_backing
> > > object is always associated with an open fuse file - that's the same as
> > > an overlayfs backing file, which is not accounted for in ulimit.
> >
> > How about restricting the backing ids to RLIMIT_NOFILE?  The @end param
> > to idr_alloc_cyclic constrains them in exactly that way.
> 
> IDK. My impression was that Miklos didn't like having a large number
> of unaccounted files, but it's up to him.
> 
> Do you have an estimate on the worst case number of backing blockdev
> for fuse iomap?

It's the upper limit on the number of block devices that you can attach
to a multi-device filesystem for use with files.  For ext4 it's 1, for
XFS it would be 2, for btrfs I have no idea.

--D

> Thanks,
> Amir.

Re: [PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Miklos Szeredi]

On Thu, 18 Sept 2025 at 20:42, Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Thu, Sep 18, 2025 at 8:17 PM Darrick J. Wong <djwong@kernel.org> wrote:

> > How about restricting the backing ids to RLIMIT_NOFILE?  The @end param
> > to idr_alloc_cyclic constrains them in exactly that way.
>
> IDK. My impression was that Miklos didn't like having a large number
> of unaccounted files, but it's up to him.

There's no 1:1 mapping between a fuse instance and a "fuse server
process", so the question is whose RLIMIT_NOFILE?  Accounting to the
process that registered the fd would be good, but implementing it
looks exceedingly complex.  Just taking RLIMIT_NOFILE value from the
process that is doing the fd registering should work, I guess.

There's still the question of unhiding these files.  Latest discussion
ended with lets create a proper directory tree for open files in proc.
I.e. /proc/PID/fdtree/FD/hidden/...

Thanks,
Miklos

Re: [PATCH 3/5] fuse: move the passthrough-specific code back to passthrough.c

[Miklos Szeredi]

On Thu, 18 Sept 2025 at 20:02, Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Wed, Sep 17, 2025 at 04:47:19AM +0200, Amir Goldstein wrote:

> > I think at this point in time FUSE_PASSTHROUGH and
> > FUSE_IOMAP should be mutually exclusive and
> > fuse_backing_ops could be set at fc level.
> > If we want to move them for per fuse_backing later
> > we can always do that when the use cases and tests arrive.
>
> With Miklos' ok I'll constrain fuse not to allow passthrough and iomap
> files on the same filesystem, but as it is now there's no technical
> reason to make it so that they can't coexist.

Is there a good reason to add the restriction?   If restricting it
doesn't simplify anything or even makes it more complex, then I'd opt
for leaving it more general, even if it doesn't seem to make sense.

Thanks,
Miklos

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Miklos Szeredi]

On Thu, 18 Sept 2025 at 18:52, Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Wed, Sep 17, 2025 at 10:18:40AM -0700, Joanne Koong wrote:

> > If I'm understanding it correctly, fc->local_fs is set to true if it's
> > a fuseblk device? Why do we need a new "ctx->local_fs" instead of
> > reusing ctx->is_bdev?
>
> Eventually, enabling iomap will also set local_fs=1, as Miklos and I
> sort of touched on a couple weeks ago:
>
> https://lore.kernel.org/linux-fsdevel/CAJfpegvmXnZc=nC4UGw5Gya2cAr-kR0s=WNecnMhdTM_mGyuUg@mail.gmail.com/

I think it might be worth making this property per-inode.   I.e. a
distributed filesystem could allow one inode to be completely "owned"
by one client.  This would be similar to NFSv4 delegations and could
be refined to read-only (shared) and read-write (exclusive) ownership.
A local filesystem would have all inodes excusively owned.

This's been long on my todo list and also have some prior experiments,
so it's a good opportunity to start working on it again:)

Thanks,
Miklos






>
> --D
>
> > Thanks,
> > Joanne
> >
> > >         err = -ENOMEM;
> > >         root = fuse_get_root_inode(sb, ctx->rootmode);
> > > @@ -2029,6 +2030,7 @@ static int fuse_init_fs_context(struct fs_context *fsc)
> > >         if (fsc->fs_type == &fuseblk_fs_type) {
> > >                 ctx->is_bdev = true;
> > >                 ctx->destroy = true;
> > > +               ctx->local_fs = true;
> > >         }
> > >  #endif
> > >
> > >

Re: [PATCH 3/5] fuse: move the passthrough-specific code back to passthrough.c

[Amir Goldstein]

On Fri, Sep 19, 2025 at 9:34 AM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Thu, 18 Sept 2025 at 20:02, Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > On Wed, Sep 17, 2025 at 04:47:19AM +0200, Amir Goldstein wrote:
>
> > > I think at this point in time FUSE_PASSTHROUGH and
> > > FUSE_IOMAP should be mutually exclusive and
> > > fuse_backing_ops could be set at fc level.
> > > If we want to move them for per fuse_backing later
> > > we can always do that when the use cases and tests arrive.
> >
> > With Miklos' ok I'll constrain fuse not to allow passthrough and iomap
> > files on the same filesystem, but as it is now there's no technical
> > reason to make it so that they can't coexist.
>
> Is there a good reason to add the restriction?   If restricting it

I guess "good reason" is subjective.
I do not like to have never tested code, but it's your fs, so up to you.

> doesn't simplify anything or even makes it more complex, then I'd opt
> for leaving it more general, even if it doesn't seem to make sense.

I don't think either restricting or not is more complex.
It's just a matter of whether fuse_backing_ops are per fuse_backing
or per fuse_conn.

It may come handy to limit the number of backing ids per fuse_conn
so that can be negotiated on FUSE_INIT, but that is independent
on the question of mutually excluding the two features.

Thanks,
Amir.

Re: [PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Amir Goldstein]

On Fri, Sep 19, 2025 at 9:14 AM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Thu, 18 Sept 2025 at 20:42, Amir Goldstein <amir73il@gmail.com> wrote:
> >
> > On Thu, Sep 18, 2025 at 8:17 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> > > How about restricting the backing ids to RLIMIT_NOFILE?  The @end param
> > > to idr_alloc_cyclic constrains them in exactly that way.
> >
> > IDK. My impression was that Miklos didn't like having a large number
> > of unaccounted files, but it's up to him.
>
> There's no 1:1 mapping between a fuse instance and a "fuse server
> process", so the question is whose RLIMIT_NOFILE?  Accounting to the
> process that registered the fd would be good, but implementing it
> looks exceedingly complex.  Just taking RLIMIT_NOFILE value from the
> process that is doing the fd registering should work, I guess.
>
> There's still the question of unhiding these files.  Latest discussion
> ended with lets create a proper directory tree for open files in proc.
> I.e. /proc/PID/fdtree/FD/hidden/...
>

Yes, well, fuse_backing_open() says:
/* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
So that's the reason I was saying there is no justification to
relax this for FUSE_IOMAP as long as this issue is not resolved.

As Darrick writes, fuse4fs needs only 1 backing blockdev
and other iomap fuse fs are unlikely to need more than a few
backing blockdevs.

So maybe, similar to max_stack_depth, we require the server to
negotiate the max_backing_id at FUSE_INIT time.

We could allow any "reasonable" number without any capabilities
and regardless of RLIMIT_NOFILE or we can account max_backing_id
in advance for the user setting up the connection.

For backward compat (or for privileged servers) zero max_backing_id
means unlimited (within the int32 range) and that requires
CAP_SYS_ADMIN for fuse_backing_open() regardless of which
type of backing file it is.

WDYT?

Thanks,
Amir.

Re: [PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Darrick J. Wong]

On Fri, Sep 19, 2025 at 11:54:39AM +0200, Amir Goldstein wrote:
> On Fri, Sep 19, 2025 at 9:14 AM Miklos Szeredi <miklos@szeredi.hu> wrote:
> >
> > On Thu, 18 Sept 2025 at 20:42, Amir Goldstein <amir73il@gmail.com> wrote:
> > >
> > > On Thu, Sep 18, 2025 at 8:17 PM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > > > How about restricting the backing ids to RLIMIT_NOFILE?  The @end param
> > > > to idr_alloc_cyclic constrains them in exactly that way.
> > >
> > > IDK. My impression was that Miklos didn't like having a large number
> > > of unaccounted files, but it's up to him.
> >
> > There's no 1:1 mapping between a fuse instance and a "fuse server
> > process", so the question is whose RLIMIT_NOFILE?  Accounting to the
> > process that registered the fd would be good, but implementing it
> > looks exceedingly complex.  Just taking RLIMIT_NOFILE value from the
> > process that is doing the fd registering should work, I guess.

Or perhaps a static limit of 1024 for now, and if someone comes up with
a humongous filesystem that needs more, we can figure out how to support
that later.

Since we're already adding flag bits to the /dev/fuse file::private_data
for synchronous init, I guess we could expand that into a full struct so
that you could open /dev/fuse, ask for various config options, and then
apply them to the fuse_dev when it gets created?

> > There's still the question of unhiding these files.  Latest discussion
> > ended with lets create a proper directory tree for open files in proc.
> > I.e. /proc/PID/fdtree/FD/hidden/...

All the iomap backing files are block devices, perhaps we could put a
symlink in /sys/block/XXX/holders/ to something associated with the
fuse_mount?  Perhaps the s_bdi?

This is a more general problem, because there's no standard way to
figure out that a given bdev is an auxiliary device attached to a
multi-device filesystems (e.g. xfs realtime volume or external log).

The downsides are that "holders" is sysfs-happy and even symlinks
require a target kobject; and lsof doesn't know about holders.  But at
least it wouldn't be 100% invisible like it is now.

> Yes, well, fuse_backing_open() says:
> /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
> So that's the reason I was saying there is no justification to
> relax this for FUSE_IOMAP as long as this issue is not resolved.
> 
> As Darrick writes, fuse4fs needs only 1 backing blockdev
> and other iomap fuse fs are unlikely to need more than a few
> backing blockdevs.

Until someone has a go at making btrfs-fuse fully functional.  But that
can be their problem. ;)

> So maybe, similar to max_stack_depth, we require the server to
> negotiate the max_backing_id at FUSE_INIT time.
> 
> We could allow any "reasonable" number without any capabilities
> and regardless of RLIMIT_NOFILE or we can account max_backing_id
> in advance for the user setting up the connection.
> 
> For backward compat (or for privileged servers) zero max_backing_id
> means unlimited (within the int32 range) and that requires
> CAP_SYS_ADMIN for fuse_backing_open() regardless of which
> type of backing file it is.
> 
> WDYT?

I think capping at 1024 now (or 256, or even 8) is fine for now, and we
can figure out the request protocol later when someone wants more.

Alternately, I wonder if there's a way to pin the fd that is used to
create the backing id so that the fuse server can't close it?  There's
probably no non-awful way to pin the fd table entry though.

--D

> Thanks,
> Amir.

Re: [PATCH 3/5] fuse: move the passthrough-specific code back to passthrough.c

[Darrick J. Wong]

On Fri, Sep 19, 2025 at 09:34:06AM +0200, Miklos Szeredi wrote:
> On Thu, 18 Sept 2025 at 20:02, Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > On Wed, Sep 17, 2025 at 04:47:19AM +0200, Amir Goldstein wrote:
> 
> > > I think at this point in time FUSE_PASSTHROUGH and
> > > FUSE_IOMAP should be mutually exclusive and
> > > fuse_backing_ops could be set at fc level.
> > > If we want to move them for per fuse_backing later
> > > we can always do that when the use cases and tests arrive.
> >
> > With Miklos' ok I'll constrain fuse not to allow passthrough and iomap
> > files on the same filesystem, but as it is now there's no technical
> > reason to make it so that they can't coexist.
> 
> Is there a good reason to add the restriction?   If restricting it
> doesn't simplify anything or even makes it more complex, then I'd opt
> for leaving it more general, even if it doesn't seem to make sense.

I don't have a good reason to add a restriction; it's entirely Amir's
concern about testing the two together.

--D

> Thanks,
> Miklos

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Darrick J. Wong]

On Fri, Sep 19, 2025 at 11:24:09AM +0200, Miklos Szeredi wrote:
> On Thu, 18 Sept 2025 at 18:52, Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > On Wed, Sep 17, 2025 at 10:18:40AM -0700, Joanne Koong wrote:
> 
> > > If I'm understanding it correctly, fc->local_fs is set to true if it's
> > > a fuseblk device? Why do we need a new "ctx->local_fs" instead of
> > > reusing ctx->is_bdev?
> >
> > Eventually, enabling iomap will also set local_fs=1, as Miklos and I
> > sort of touched on a couple weeks ago:
> >
> > https://lore.kernel.org/linux-fsdevel/CAJfpegvmXnZc=nC4UGw5Gya2cAr-kR0s=WNecnMhdTM_mGyuUg@mail.gmail.com/
> 
> I think it might be worth making this property per-inode.   I.e. a
> distributed filesystem could allow one inode to be completely "owned"
> by one client.  This would be similar to NFSv4 delegations and could
> be refined to read-only (shared) and read-write (exclusive) ownership.
> A local filesystem would have all inodes excusively owned.
> 
> This's been long on my todo list and also have some prior experiments,
> so it's a good opportunity to start working on it again:)

Since I already have per-fs and per-inode iomap flags, I can add a
per-inode localfs flag pretty easily for v6.  ATM I see 2 existing flags
and 5 proposed (out of 32 possible):

/**
 * fuse_attr flags
 *
 * FUSE_ATTR_SUBMOUNT: Object is a submount root
 * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
 * FUSE_ATTR_IOMAP: Use iomap for this inode
 * FUSE_ATTR_ATOMIC: Enable untorn writes
 * FUSE_ATTR_SYNC: File writes are synchronous
 * FUSE_ATTR_IMMUTABLE: File is immutable
 * FUSE_ATTR_APPEND: File is append-only
 */

So we still have plenty of space.

Would you like to allow any server set the per-inode flag?  Or would you
rather keep the per-fs flag and require that it's set before setting the
per-inode flag?  That would be useful for privilege checking of the fuse
server.

--D

> Thanks,
> Miklos
> 
> 
> 
> 
> 
> 
> >
> > --D
> >
> > > Thanks,
> > > Joanne
> > >
> > > >         err = -ENOMEM;
> > > >         root = fuse_get_root_inode(sb, ctx->rootmode);
> > > > @@ -2029,6 +2030,7 @@ static int fuse_init_fs_context(struct fs_context *fsc)
> > > >         if (fsc->fs_type == &fuseblk_fs_type) {
> > > >                 ctx->is_bdev = true;
> > > >                 ctx->destroy = true;
> > > > +               ctx->local_fs = true;
> > > >         }
> > > >  #endif
> > > >
> > > >

Re: [PATCH 01/28] fuse: implement the basic iomap mechanisms

[Joanne Koong]

On Mon, Sep 15, 2025 at 5:28 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> Implement functions to enable upcalling of iomap_begin and iomap_end to
> userspace fuse servers.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  fs/fuse/fuse_i.h          |   35 ++++
>  fs/fuse/iomap_priv.h      |   36 ++++
>  include/uapi/linux/fuse.h |   90 +++++++++
>  fs/fuse/Kconfig           |   32 +++
>  fs/fuse/Makefile          |    1
>  fs/fuse/file_iomap.c      |  434 +++++++++++++++++++++++++++++++++++++++++++++
>  fs/fuse/inode.c           |    9 +
>  7 files changed, 636 insertions(+), 1 deletion(-)
>  create mode 100644 fs/fuse/iomap_priv.h
>  create mode 100644 fs/fuse/file_iomap.c
>
>
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index 4560687d619d76..f0d408a6e12c32 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -923,6 +923,9 @@ struct fuse_conn {
>         /* Is synchronous FUSE_INIT allowed? */
>         unsigned int sync_init:1;
>
> +       /* Enable fs/iomap for file operations */
> +       unsigned int iomap:1;
> +
>         /* Use io_uring for communication */
>         unsigned int io_uring;
>
> @@ -1047,6 +1050,11 @@ static inline struct fuse_mount *get_fuse_mount_super(struct super_block *sb)
>         return sb->s_fs_info;
>  }
>
> +static inline const struct fuse_mount *get_fuse_mount_super_c(const struct super_block *sb)
> +{
> +       return sb->s_fs_info;
> +}
> +
>  static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
>  {
>         return get_fuse_mount_super(sb)->fc;
> @@ -1057,16 +1065,31 @@ static inline struct fuse_mount *get_fuse_mount(struct inode *inode)
>         return get_fuse_mount_super(inode->i_sb);
>  }
>
> +static inline const struct fuse_mount *get_fuse_mount_c(const struct inode *inode)
> +{
> +       return get_fuse_mount_super_c(inode->i_sb);
> +}
> +
>  static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
>  {
>         return get_fuse_mount_super(inode->i_sb)->fc;
>  }
>
> +static inline const struct fuse_conn *get_fuse_conn_c(const struct inode *inode)
> +{
> +       return get_fuse_mount_super_c(inode->i_sb)->fc;
> +}
> +
>  static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
>  {
>         return container_of(inode, struct fuse_inode, inode);
>  }
>
> +static inline const struct fuse_inode *get_fuse_inode_c(const struct inode *inode)
> +{
> +       return container_of(inode, struct fuse_inode, inode);
> +}

Do we need these new set of helpers? AFAICT it does two things: a)
guarantee constness of the arg passed in b) guarantee constness of the
pointer returned

But it seems like for a) we could get that by modifying the existing
functions to take in a const arg, eg

-static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
+static inline struct fuse_inode *get_fuse_inode(const struct inode *inode)
 {
      return container_of(inode, struct fuse_inode, inode);
 }

and for b) it seems to me like the caller enforces the constness of
the pointer returned whether the actual function returns a const
pointer or not,

eg
const struct fuse_inode *fi = get_fuse_inode{_c}(inode);

Maybe I'm missing something here but it seems to me like we don't need
these new helpers?

> +
> diff --git a/fs/fuse/iomap_priv.h b/fs/fuse/iomap_priv.h

btw, i think the general convention is to use "_i.h" suffixing for
private internal files, eg fuse_i.h, fuse_dev_i.h, dev_uring_i.h

> new file mode 100644
> index 00000000000000..243d92cb625095
> --- /dev/null
> +++ b/fs/fuse/iomap_priv.h
> @@ -0,0 +1,36 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> + * Author: Darrick J. Wong <djwong@kernel.org>
> + */
> +#ifndef _FS_FUSE_IOMAP_PRIV_H
> +#define _FS_FUSE_IOMAP_PRIV_H
> +
...
> diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> index 31b80f93211b81..3634cbe602cd9c 100644
> --- a/include/uapi/linux/fuse.h
> +++ b/include/uapi/linux/fuse.h
> @@ -235,6 +235,9 @@
>   *
>   *  7.44
>   *  - add FUSE_NOTIFY_INC_EPOCH
> + *
> + *  7.99

Just curious, where did you get the .99 from?

> + *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
>   */
>
>  #ifndef _LINUX_FUSE_H
> @@ -270,7 +273,7 @@
>  #define FUSE_KERNEL_VERSION 7
> diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> index 9563fa5387a241..67dfe300bf2e07 100644
> --- a/fs/fuse/Kconfig
> +++ b/fs/fuse/Kconfig
> @@ -69,6 +69,38 @@ config FUSE_PASSTHROUGH
> +config FUSE_IOMAP_DEBUG
> +       bool "Debug FUSE file IO over iomap"
> +       default n
> +       depends on FUSE_IOMAP
> +       help
> +         Enable debugging assertions for the fuse iomap code paths and logging
> +         of bad iomap file mapping data being sent to the kernel.
> +

I wonder if we should have a general FUSE_DEBUG that this would fall
under instead of creating one that's iomap_debug specific

>  config FUSE_IO_URING
>         bool "FUSE communication over io-uring"
>         default y
> diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
> index 46041228e5be2c..27be39317701d6 100644
> --- a/fs/fuse/Makefile
> +++ b/fs/fuse/Makefile
> @@ -18,5 +18,6 @@ fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
>  fuse-$(CONFIG_FUSE_BACKING) += backing.o
>  fuse-$(CONFIG_SYSCTL) += sysctl.o
>  fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
> +fuse-$(CONFIG_FUSE_IOMAP) += file_iomap.o
>
>  virtiofs-y := virtio_fs.o
> diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> new file mode 100644
> index 00000000000000..dda757768d3ea6
> --- /dev/null
> +++ b/fs/fuse/file_iomap.c
> @@ -0,0 +1,434 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> + * Author: Darrick J. Wong <djwong@kernel.org>
> + */
> +#include <linux/iomap.h>
> +#include "fuse_i.h"
> +#include "fuse_trace.h"
> +#include "iomap_priv.h"
> +
> +/* Validate FUSE_IOMAP_TYPE_* */
> +static inline bool fuse_iomap_check_type(uint16_t fuse_type)
> +{
> +       switch (fuse_type) {
> +       case FUSE_IOMAP_TYPE_HOLE:
> +       case FUSE_IOMAP_TYPE_DELALLOC:
> +       case FUSE_IOMAP_TYPE_MAPPED:
> +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> +       case FUSE_IOMAP_TYPE_INLINE:
> +       case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
> +               return true;
> +       }
> +
> +       return false;
> +}

Maybe faster to check by using a bitmask instead?


> +
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index 1e7298b2b89b58..32f4b7c9a20a8a 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -1448,6 +1448,13 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
>
>                         if (flags & FUSE_REQUEST_TIMEOUT)
>                                 timeout = arg->request_timeout;
> +
> +                       if ((flags & FUSE_IOMAP) && fuse_iomap_enabled()) {
> +                               fc->local_fs = 1;
> +                               fc->iomap = 1;
> +                               printk(KERN_WARNING
> + "fuse: EXPERIMENTAL iomap feature enabled.  Use at your own risk!");
> +                       }

pr_warn() seems to be the convention elsewhere in the fuse code


Thanks,
Joanne
>                 } else {
>                         ra_pages = fc->max_read / PAGE_SIZE;
>                         fc->no_lock = 1;
> @@ -1516,6 +1523,8 @@ static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
>          */
>         if (fuse_uring_enabled())
>                 flags |= FUSE_OVER_IO_URING;
> +       if (fuse_iomap_enabled())
> +               flags |= FUSE_IOMAP;
>
>         ia->in.flags = flags;
>         ia->in.flags2 = flags >> 32;
>

Re: [PATCH 04/28] fuse: adapt FUSE_DEV_IOC_BACKING_{OPEN,CLOSE} to add new iomap devices

[Miklos Szeredi]

On Fri, 19 Sept 2025 at 19:42, Darrick J. Wong <djwong@kernel.org> wrote:
> I think capping at 1024 now (or 256, or even 8) is fine for now, and we
> can figure out the request protocol later when someone wants more.

Yeah, whichever.

> Alternately, I wonder if there's a way to pin the fd that is used to
> create the backing id so that the fuse server can't close it?  There's
> probably no non-awful way to pin the fd table entry though.

I don't think this could work.

My idea back then was to create a kernel thread for each fuse instance
and have FUSE_DEV_IOC_BACKING_OPEN/_CLOSE operate on the file table of
this thread.  Not sure how practical this would be.

Thanks,
Miklos


>
> --D
>
> > Thanks,
> > Amir.

Re: [PATCH 1/8] fuse: fix livelock in synchronous file put from fuseblk workers

[Miklos Szeredi]

On Tue, 16 Sept 2025 at 02:24, Darrick J. Wong <djwong@kernel.org> wrote:

> Fix this by only using asynchronous fputs when closing files, and leave
> a comment explaining why.
>
> Cc: <stable@vger.kernel.org> # v2.6.38
> Fixes: 5a18ec176c934c ("fuse: fix hang of single threaded fuseblk filesystem")
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

Applied, thanks.

Miklos

Re: [PATCH 3/8] fuse: capture the unique id of fuse commands being sent

[Miklos Szeredi]

On Tue, 16 Sept 2025 at 02:24, Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> The fuse_request_{send,end} tracepoints capture the value of
> req->in.h.unique in the trace output.  It would be really nice if we
> could use this to match a request to its response for debugging and
> latency analysis, but the call to trace_fuse_request_send occurs before
> the unique id has been set:
>
> fuse_request_send:    connection 8388608 req 0 opcode 1 (FUSE_LOOKUP) len 107
> fuse_request_end:     connection 8388608 req 6 len 16 error -2
>
> (Notice that req moves from 0 to 6)
>
> Move the callsites to trace_fuse_request_send to after the unique id has
> been set by introducing a helper to do that for standard fuse_req
> requests.  FUSE_FORGET requests are not covered by this because they
> appear to be synthesized into the event stream without a fuse_req
> object and are never replied to.
>
> Requests that are aborted without ever having been submitted to the fuse
> server retain the behavior that only the fuse_request_end tracepoint
> shows up in the trace record, and with req==0.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

Applied, thanks.

Miklos

Re: [PATCH 8/8] fuse: enable FUSE_SYNCFS for all fuseblk servers

[Miklos Szeredi]

On Tue, 16 Sept 2025 at 02:26, Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> Turn on syncfs for all fuseblk servers so that the ones in the know can
> flush cached intermediate data and logs to disk.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

Applied, thanks.

Miklos

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Miklos Szeredi]

On Tue, 16 Sept 2025 at 02:24, Darrick J. Wong <djwong@kernel.org> wrote:

> +       /*
> +        * Wait for all the events to complete or abort.  Touch the watchdog
> +        * once per second so that we don't trip the hangcheck timer while
> +        * waiting for the fuse server.
> +        */
> +       smp_mb();
> +       while (wait_event_timeout(fc->blocked_waitq,
> +                       !fc->connected || atomic_read(&fc->num_waiting) == 0,
> +                       HZ) == 0)

I applied this patch, but then realized that I don't understand what's
going on here.

Why is this site special?  Should the other waits for server response
be treated like this?

Thanks,
Miklos

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Darrick J. Wong]

On Tue, Sep 23, 2025 at 01:11:39PM +0200, Miklos Szeredi wrote:
> On Tue, 16 Sept 2025 at 02:24, Darrick J. Wong <djwong@kernel.org> wrote:
> 
> > +       /*
> > +        * Wait for all the events to complete or abort.  Touch the watchdog
> > +        * once per second so that we don't trip the hangcheck timer while
> > +        * waiting for the fuse server.
> > +        */
> > +       smp_mb();
> > +       while (wait_event_timeout(fc->blocked_waitq,
> > +                       !fc->connected || atomic_read(&fc->num_waiting) == 0,
> > +                       HZ) == 0)
> 
> I applied this patch, but then realized that I don't understand what's
> going on here.

We go around this tight loop until either 1 second goes by, the fuse
connection drops, or the number of fuse commands hits zero.  Non-timeout
Wakeups are stimulated by the wake_up_all(&fc->blocked_waitq) in
fuse_drop_waiting() after the request is completed or aborted.

The loop body touches the soft lockup watchdog so that we don't get hung
task warnings while waiting for a possibly large number of RELEASE
requests (or whatever's queued up at that point) to be processed by the
server.  I didn't use wait_event_killable_timeout because I don't know
how to clean up an in-progress unmount midway through.

> Why is this site special?  Should the other waits for server response
> be treated like this?

I'm not sure what you're referring to by "special" -- are you asking
about why I added the touch_softlockup_watchdog() call here but not in
fuse_wait_aborted()?  I think it could use that treatment too, but once
you abort all the pending requests they tend to go away very quickly.
It might be the case that nobody's gotten a warning simply because the
aborted requests all go away in under 30 seconds.

--D

> Thanks,
> Miklos

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Miklos Szeredi]

On Fri, 19 Sept 2025 at 19:50, Darrick J. Wong <djwong@kernel.org> wrote:

> /**
>  * fuse_attr flags
>  *
>  * FUSE_ATTR_SUBMOUNT: Object is a submount root
>  * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
>  * FUSE_ATTR_IOMAP: Use iomap for this inode
>  * FUSE_ATTR_ATOMIC: Enable untorn writes
>  * FUSE_ATTR_SYNC: File writes are synchronous
>  * FUSE_ATTR_IMMUTABLE: File is immutable
>  * FUSE_ATTR_APPEND: File is append-only
>  */
>
> So we still have plenty of space.

No, I was thinking of an internal flag or flags.  Exporting this to
the server will come at some point, but not now.

So for now something like

/** FUSE inode state bits */
enum {
...
    /* Exclusive access to file, either because fs is local or have an
exclusive "lease" on distributed fs */
    FUSE_I_EXCLUSIVE,
};

Thanks,
Miklos

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Miklos Szeredi]

On Tue, 23 Sept 2025 at 16:54, Darrick J. Wong <djwong@kernel.org> wrote:

> I'm not sure what you're referring to by "special" -- are you asking
> about why I added the touch_softlockup_watchdog() call here but not in
> fuse_wait_aborted()?  I think it could use that treatment too, but once
> you abort all the pending requests they tend to go away very quickly.
> It might be the case that nobody's gotten a warning simply because the
> aborted requests all go away in under 30 seconds.

Maybe I'm not understanding how the softlockup detector works.  I
thought that it triggers if task is spinning in a tight loop.  That
precludes any timeouts, since that means that the task went to sleep.

So what's happening here?

Thanks,
Miklos

Re: [PATCH 01/28] fuse: implement the basic iomap mechanisms

[Darrick J. Wong]

On Fri, Sep 19, 2025 at 03:36:52PM -0700, Joanne Koong wrote:
> On Mon, Sep 15, 2025 at 5:28 PM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > From: Darrick J. Wong <djwong@kernel.org>
> >
> > Implement functions to enable upcalling of iomap_begin and iomap_end to
> > userspace fuse servers.
> >
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  fs/fuse/fuse_i.h          |   35 ++++
> >  fs/fuse/iomap_priv.h      |   36 ++++
> >  include/uapi/linux/fuse.h |   90 +++++++++
> >  fs/fuse/Kconfig           |   32 +++
> >  fs/fuse/Makefile          |    1
> >  fs/fuse/file_iomap.c      |  434 +++++++++++++++++++++++++++++++++++++++++++++
> >  fs/fuse/inode.c           |    9 +
> >  7 files changed, 636 insertions(+), 1 deletion(-)
> >  create mode 100644 fs/fuse/iomap_priv.h
> >  create mode 100644 fs/fuse/file_iomap.c
> >
> >
> > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > index 4560687d619d76..f0d408a6e12c32 100644
> > --- a/fs/fuse/fuse_i.h
> > +++ b/fs/fuse/fuse_i.h
> > @@ -923,6 +923,9 @@ struct fuse_conn {
> >         /* Is synchronous FUSE_INIT allowed? */
> >         unsigned int sync_init:1;
> >
> > +       /* Enable fs/iomap for file operations */
> > +       unsigned int iomap:1;
> > +
> >         /* Use io_uring for communication */
> >         unsigned int io_uring;
> >
> > @@ -1047,6 +1050,11 @@ static inline struct fuse_mount *get_fuse_mount_super(struct super_block *sb)
> >         return sb->s_fs_info;
> >  }
> >
> > +static inline const struct fuse_mount *get_fuse_mount_super_c(const struct super_block *sb)
> > +{
> > +       return sb->s_fs_info;
> > +}
> > +
> >  static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
> >  {
> >         return get_fuse_mount_super(sb)->fc;
> > @@ -1057,16 +1065,31 @@ static inline struct fuse_mount *get_fuse_mount(struct inode *inode)
> >         return get_fuse_mount_super(inode->i_sb);
> >  }
> >
> > +static inline const struct fuse_mount *get_fuse_mount_c(const struct inode *inode)
> > +{
> > +       return get_fuse_mount_super_c(inode->i_sb);
> > +}
> > +
> >  static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
> >  {
> >         return get_fuse_mount_super(inode->i_sb)->fc;
> >  }
> >
> > +static inline const struct fuse_conn *get_fuse_conn_c(const struct inode *inode)
> > +{
> > +       return get_fuse_mount_super_c(inode->i_sb)->fc;
> > +}
> > +
> >  static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
> >  {
> >         return container_of(inode, struct fuse_inode, inode);
> >  }
> >
> > +static inline const struct fuse_inode *get_fuse_inode_c(const struct inode *inode)
> > +{
> > +       return container_of(inode, struct fuse_inode, inode);
> > +}
> 
> Do we need these new set of helpers? AFAICT it does two things: a)
> guarantee constness of the arg passed in b) guarantee constness of the
> pointer returned
> 
> But it seems like for a) we could get that by modifying the existing
> functions to take in a const arg, eg
> 
> -static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
> +static inline struct fuse_inode *get_fuse_inode(const struct inode *inode)
>  {
>       return container_of(inode, struct fuse_inode, inode);
>  }
> 
> and for b) it seems to me like the caller enforces the constness of
> the pointer returned whether the actual function returns a const
> pointer or not,
> 
> eg
> const struct fuse_inode *fi = get_fuse_inode{_c}(inode);
> 
> Maybe I'm missing something here but it seems to me like we don't need
> these new helpers?

Heh.  I had mistakenly thought that one cannot cast a const struct
pointer to a mutable const struct pointer, but I just tried your
suggestion and it seemed to work fine.  So I guess we don't need
get_fuse_mount_c either.

Yay C, all it's doing is taking a number pointing to something that
can't be changed, subtracting from it, and thus returning a different
number.  Perhaps Rust has polluted my brain.

> > +
> > diff --git a/fs/fuse/iomap_priv.h b/fs/fuse/iomap_priv.h
> 
> btw, i think the general convention is to use "_i.h" suffixing for
> private internal files, eg fuse_i.h, fuse_dev_i.h, dev_uring_i.h

Noted, thank you.

> > new file mode 100644
> > index 00000000000000..243d92cb625095
> > --- /dev/null
> > +++ b/fs/fuse/iomap_priv.h
> > @@ -0,0 +1,36 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> > + * Author: Darrick J. Wong <djwong@kernel.org>
> > + */
> > +#ifndef _FS_FUSE_IOMAP_PRIV_H
> > +#define _FS_FUSE_IOMAP_PRIV_H
> > +
> ...
> > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > index 31b80f93211b81..3634cbe602cd9c 100644
> > --- a/include/uapi/linux/fuse.h
> > +++ b/include/uapi/linux/fuse.h
> > @@ -235,6 +235,9 @@
> >   *
> >   *  7.44
> >   *  - add FUSE_NOTIFY_INC_EPOCH
> > + *
> > + *  7.99
> 
> Just curious, where did you get the .99 from?

Any time I go adding to a versioned ABI, I try to use high numbers (and
high bits for flags) so that it's really obvious that the new flags are
in use when I poke through crash/gdb/etc.

For permanent artifacts like an ondisk format, it's convenient to cache
fs images for fuzz testing, etc.  Using a high bit/number reduces the
chance that someone else's new feature will get merged and cause
conflicts, which force me to regenerate all cached images.

Obviously at merge time I change these values to use lower bit positions
or version numbers to fit the merge target so it doesn't completely
eliminate the caching problems.

> > + *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
> >   */
> >
> >  #ifndef _LINUX_FUSE_H
> > @@ -270,7 +273,7 @@
> >  #define FUSE_KERNEL_VERSION 7
> > diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> > index 9563fa5387a241..67dfe300bf2e07 100644
> > --- a/fs/fuse/Kconfig
> > +++ b/fs/fuse/Kconfig
> > @@ -69,6 +69,38 @@ config FUSE_PASSTHROUGH
> > +config FUSE_IOMAP_DEBUG
> > +       bool "Debug FUSE file IO over iomap"
> > +       default n
> > +       depends on FUSE_IOMAP
> > +       help
> > +         Enable debugging assertions for the fuse iomap code paths and logging
> > +         of bad iomap file mapping data being sent to the kernel.
> > +
> 
> I wonder if we should have a general FUSE_DEBUG that this would fall
> under instead of creating one that's iomap_debug specific

Probably, but I was also trying to keep this as localized to iomap as
possible.  If Miklos would rather I extend it to all of fuse (which is
probably a good idea!) then I'm happy to do so.

> >  config FUSE_IO_URING
> >         bool "FUSE communication over io-uring"
> >         default y
> > diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
> > index 46041228e5be2c..27be39317701d6 100644
> > --- a/fs/fuse/Makefile
> > +++ b/fs/fuse/Makefile
> > @@ -18,5 +18,6 @@ fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
> >  fuse-$(CONFIG_FUSE_BACKING) += backing.o
> >  fuse-$(CONFIG_SYSCTL) += sysctl.o
> >  fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
> > +fuse-$(CONFIG_FUSE_IOMAP) += file_iomap.o
> >
> >  virtiofs-y := virtio_fs.o
> > diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> > new file mode 100644
> > index 00000000000000..dda757768d3ea6
> > --- /dev/null
> > +++ b/fs/fuse/file_iomap.c
> > @@ -0,0 +1,434 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> > + * Author: Darrick J. Wong <djwong@kernel.org>
> > + */
> > +#include <linux/iomap.h>
> > +#include "fuse_i.h"
> > +#include "fuse_trace.h"
> > +#include "iomap_priv.h"
> > +
> > +/* Validate FUSE_IOMAP_TYPE_* */
> > +static inline bool fuse_iomap_check_type(uint16_t fuse_type)
> > +{
> > +       switch (fuse_type) {
> > +       case FUSE_IOMAP_TYPE_HOLE:
> > +       case FUSE_IOMAP_TYPE_DELALLOC:
> > +       case FUSE_IOMAP_TYPE_MAPPED:
> > +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> > +       case FUSE_IOMAP_TYPE_INLINE:
> > +       case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
> > +               return true;
> > +       }
> > +
> > +       return false;
> > +}
> 
> Maybe faster to check by using a bitmask instead?

They're consecutive; one could #define a FUSE_IOMAP_TYPE_MAX to alias
PURE_OVERWRITE and collapse the whole check to:

	return fuse_type <= FUSE_IOMAP_TYPE_MAX;

> > +
> > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > index 1e7298b2b89b58..32f4b7c9a20a8a 100644
> > --- a/fs/fuse/inode.c
> > +++ b/fs/fuse/inode.c
> > @@ -1448,6 +1448,13 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
> >
> >                         if (flags & FUSE_REQUEST_TIMEOUT)
> >                                 timeout = arg->request_timeout;
> > +
> > +                       if ((flags & FUSE_IOMAP) && fuse_iomap_enabled()) {
> > +                               fc->local_fs = 1;
> > +                               fc->iomap = 1;
> > +                               printk(KERN_WARNING
> > + "fuse: EXPERIMENTAL iomap feature enabled.  Use at your own risk!");
> > +                       }
> 
> pr_warn() seems to be the convention elsewhere in the fuse code

Ah, thanks.  Do you know why fuse calls pr_warn("fuse: XXX") instead of
the usual sequence of

#define pr_fmt(fmt) "fuse: " fmt

so that "fuse: " gets included automatically?

--D

> 
> Thanks,
> Joanne
> >                 } else {
> >                         ra_pages = fc->max_read / PAGE_SIZE;
> >                         fc->no_lock = 1;
> > @@ -1516,6 +1523,8 @@ static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
> >          */
> >         if (fuse_uring_enabled())
> >                 flags |= FUSE_OVER_IO_URING;
> > +       if (fuse_iomap_enabled())
> > +               flags |= FUSE_IOMAP;
> >
> >         ia->in.flags = flags;
> >         ia->in.flags2 = flags >> 32;
> >
> 

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Darrick J. Wong]

On Tue, Sep 23, 2025 at 04:57:30PM +0200, Miklos Szeredi wrote:
> On Fri, 19 Sept 2025 at 19:50, Darrick J. Wong <djwong@kernel.org> wrote:
> 
> > /**
> >  * fuse_attr flags
> >  *
> >  * FUSE_ATTR_SUBMOUNT: Object is a submount root
> >  * FUSE_ATTR_DAX: Enable DAX for this file in per inode DAX mode
> >  * FUSE_ATTR_IOMAP: Use iomap for this inode
> >  * FUSE_ATTR_ATOMIC: Enable untorn writes
> >  * FUSE_ATTR_SYNC: File writes are synchronous
> >  * FUSE_ATTR_IMMUTABLE: File is immutable
> >  * FUSE_ATTR_APPEND: File is append-only
> >  */
> >
> > So we still have plenty of space.
> 
> No, I was thinking of an internal flag or flags.  Exporting this to
> the server will come at some point, but not now.
> 
> So for now something like
> 
> /** FUSE inode state bits */
> enum {
> ...
>     /* Exclusive access to file, either because fs is local or have an
> exclusive "lease" on distributed fs */
>     FUSE_I_EXCLUSIVE,
> };

Oh, ok.  I can do that.  Just to be clear about what I need to do for
v6:

* fuse_conn::is_local goes away
* FUSE_I_* gains a new FUSE_I_EXCLUSIVE flag
* "local" operations check for FUSE_I_EXCLUSIVE instead of local_fs
* fuseblk filesystems always set FUSE_I_EXCLUSIVE
* iomap filesystems (when they arrive) always set FUSE_I_EXCLUSIVE

Right?

--D

> Thanks,
> Miklos
> 

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Darrick J. Wong]

On Tue, Sep 23, 2025 at 08:56:47PM +0200, Miklos Szeredi wrote:
> On Tue, 23 Sept 2025 at 16:54, Darrick J. Wong <djwong@kernel.org> wrote:
> 
> > I'm not sure what you're referring to by "special" -- are you asking
> > about why I added the touch_softlockup_watchdog() call here but not in
> > fuse_wait_aborted()?  I think it could use that treatment too, but once
> > you abort all the pending requests they tend to go away very quickly.
> > It might be the case that nobody's gotten a warning simply because the
> > aborted requests all go away in under 30 seconds.
> 
> Maybe I'm not understanding how the softlockup detector works.  I
> thought that it triggers if task is spinning in a tight loop.  That
> precludes any timeouts, since that means that the task went to sleep.
> 
> So what's happening here?

Hrm, I thought the softlockup detector also complains about tasks stuck
in uninterruptible sleep, but you're right, it *does* schedule() so the
softlockup detector won't complain about it.

I think.  Let me go try to prove that empirically. :)

--D

> Thanks,
> Miklos
> 

Re: [PATCH 01/28] fuse: implement the basic iomap mechanisms

[Joanne Koong]

On Tue, Sep 23, 2025 at 1:32 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Fri, Sep 19, 2025 at 03:36:52PM -0700, Joanne Koong wrote:
> > On Mon, Sep 15, 2025 at 5:28 PM Darrick J. Wong <djwong@kernel.org> wrote:
> > >
> > > From: Darrick J. Wong <djwong@kernel.org>
> > >
> > > Implement functions to enable upcalling of iomap_begin and iomap_end to
> > > userspace fuse servers.
> > >
> > > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > > ---
> > >  fs/fuse/fuse_i.h          |   35 ++++
> > >  fs/fuse/iomap_priv.h      |   36 ++++
> > >  include/uapi/linux/fuse.h |   90 +++++++++
> > >  fs/fuse/Kconfig           |   32 +++
> > >  fs/fuse/Makefile          |    1
> > >  fs/fuse/file_iomap.c      |  434 +++++++++++++++++++++++++++++++++++++++++++++
> > >  fs/fuse/inode.c           |    9 +
> > >  7 files changed, 636 insertions(+), 1 deletion(-)
> > >  create mode 100644 fs/fuse/iomap_priv.h
> > >  create mode 100644 fs/fuse/file_iomap.c
> > >
> > > new file mode 100644
> > > index 00000000000000..243d92cb625095
> > > --- /dev/null
> > > +++ b/fs/fuse/iomap_priv.h
> > > @@ -0,0 +1,36 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> > > + * Author: Darrick J. Wong <djwong@kernel.org>
> > > + */
> > > +#ifndef _FS_FUSE_IOMAP_PRIV_H
> > > +#define _FS_FUSE_IOMAP_PRIV_H
> > > +
> > ...
> > > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > > index 31b80f93211b81..3634cbe602cd9c 100644
> > > --- a/include/uapi/linux/fuse.h
> > > +++ b/include/uapi/linux/fuse.h
> > > @@ -235,6 +235,9 @@
> > >   *
> > >   *  7.44
> > >   *  - add FUSE_NOTIFY_INC_EPOCH
> > > + *
> > > + *  7.99
> >
> > Just curious, where did you get the .99 from?
>
> Any time I go adding to a versioned ABI, I try to use high numbers (and
> high bits for flags) so that it's really obvious that the new flags are
> in use when I poke through crash/gdb/etc.
>
> For permanent artifacts like an ondisk format, it's convenient to cache
> fs images for fuzz testing, etc.  Using a high bit/number reduces the
> chance that someone else's new feature will get merged and cause
> conflicts, which force me to regenerate all cached images.
>
> Obviously at merge time I change these values to use lower bit positions
> or version numbers to fit the merge target so it doesn't completely
> eliminate the caching problems.

Ahh okay I see, thanks for the explanation!

>
> > > + *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
> > >   */
> > >
> > >  #ifndef _LINUX_FUSE_H
> > > @@ -270,7 +273,7 @@
> > >  #define FUSE_KERNEL_VERSION 7
> > > diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> > > index 9563fa5387a241..67dfe300bf2e07 100644
> > > --- a/fs/fuse/Kconfig
> > > +++ b/fs/fuse/Kconfig
> > > @@ -69,6 +69,38 @@ config FUSE_PASSTHROUGH
> > > +config FUSE_IOMAP_DEBUG
> > > +       bool "Debug FUSE file IO over iomap"
> > > +       default n
> > > +       depends on FUSE_IOMAP
> > > +       help
> > > +         Enable debugging assertions for the fuse iomap code paths and logging
> > > +         of bad iomap file mapping data being sent to the kernel.
> > > +
> >
> > I wonder if we should have a general FUSE_DEBUG that this would fall
> > under instead of creating one that's iomap_debug specific
>
> Probably, but I was also trying to keep this as localized to iomap as
> possible.  If Miklos would rather I extend it to all of fuse (which is
> probably a good idea!) then I'm happy to do so.
>
> > >  config FUSE_IO_URING
> > >         bool "FUSE communication over io-uring"
> > >         default y
> > > diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
> > > index 46041228e5be2c..27be39317701d6 100644
> > > --- a/fs/fuse/Makefile
> > > +++ b/fs/fuse/Makefile
> > > @@ -18,5 +18,6 @@ fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
> > >  fuse-$(CONFIG_FUSE_BACKING) += backing.o
> > >  fuse-$(CONFIG_SYSCTL) += sysctl.o
> > >  fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
> > > +fuse-$(CONFIG_FUSE_IOMAP) += file_iomap.o
> > >
> > >  virtiofs-y := virtio_fs.o
> > > diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> > > new file mode 100644
> > > index 00000000000000..dda757768d3ea6
> > > --- /dev/null
> > > +++ b/fs/fuse/file_iomap.c
> > > @@ -0,0 +1,434 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> > > + * Author: Darrick J. Wong <djwong@kernel.org>
> > > + */
> > > +#include <linux/iomap.h>
> > > +#include "fuse_i.h"
> > > +#include "fuse_trace.h"
> > > +#include "iomap_priv.h"
> > > +
> > > +/* Validate FUSE_IOMAP_TYPE_* */
> > > +static inline bool fuse_iomap_check_type(uint16_t fuse_type)
> > > +{
> > > +       switch (fuse_type) {
> > > +       case FUSE_IOMAP_TYPE_HOLE:
> > > +       case FUSE_IOMAP_TYPE_DELALLOC:
> > > +       case FUSE_IOMAP_TYPE_MAPPED:
> > > +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> > > +       case FUSE_IOMAP_TYPE_INLINE:
> > > +       case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
> > > +               return true;
> > > +       }
> > > +
> > > +       return false;
> > > +}
> >
> > Maybe faster to check by using a bitmask instead?
>
> They're consecutive; one could #define a FUSE_IOMAP_TYPE_MAX to alias
> PURE_OVERWRITE and collapse the whole check to:
>
>         return fuse_type <= FUSE_IOMAP_TYPE_MAX;
>
> > > +
> > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > > index 1e7298b2b89b58..32f4b7c9a20a8a 100644
> > > --- a/fs/fuse/inode.c
> > > +++ b/fs/fuse/inode.c
> > > @@ -1448,6 +1448,13 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
> > >
> > >                         if (flags & FUSE_REQUEST_TIMEOUT)
> > >                                 timeout = arg->request_timeout;
> > > +
> > > +                       if ((flags & FUSE_IOMAP) && fuse_iomap_enabled()) {
> > > +                               fc->local_fs = 1;
> > > +                               fc->iomap = 1;
> > > +                               printk(KERN_WARNING
> > > + "fuse: EXPERIMENTAL iomap feature enabled.  Use at your own risk!");
> > > +                       }
> >
> > pr_warn() seems to be the convention elsewhere in the fuse code
>
> Ah, thanks.  Do you know why fuse calls pr_warn("fuse: XXX") instead of
> the usual sequence of
>
> #define pr_fmt(fmt) "fuse: " fmt
>
> so that "fuse: " gets included automatically?

I think it does do this, or at least that's what I see in fuse_i.h :D

Thanks,
Joanne
>
> --D
>
> >
> > Thanks,
> > Joanne
> > >                 } else {
> > >                         ra_pages = fc->max_read / PAGE_SIZE;
> > >                         fc->no_lock = 1;
> > > @@ -1516,6 +1523,8 @@ static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
> > >          */
> > >         if (fuse_uring_enabled())
> > >                 flags |= FUSE_OVER_IO_URING;
> > > +       if (fuse_iomap_enabled())
> > > +               flags |= FUSE_IOMAP;
> > >
> > >         ia->in.flags = flags;
> > >         ia->in.flags2 = flags >> 32;
> > >
> >

Re: [PATCH 01/28] fuse: implement the basic iomap mechanisms

[Darrick J. Wong]

On Tue, Sep 23, 2025 at 02:24:21PM -0700, Joanne Koong wrote:
> On Tue, Sep 23, 2025 at 1:32 PM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > On Fri, Sep 19, 2025 at 03:36:52PM -0700, Joanne Koong wrote:
> > > On Mon, Sep 15, 2025 at 5:28 PM Darrick J. Wong <djwong@kernel.org> wrote:
> > > >
> > > > From: Darrick J. Wong <djwong@kernel.org>
> > > >
> > > > Implement functions to enable upcalling of iomap_begin and iomap_end to
> > > > userspace fuse servers.
> > > >
> > > > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > > > ---
> > > >  fs/fuse/fuse_i.h          |   35 ++++
> > > >  fs/fuse/iomap_priv.h      |   36 ++++
> > > >  include/uapi/linux/fuse.h |   90 +++++++++
> > > >  fs/fuse/Kconfig           |   32 +++
> > > >  fs/fuse/Makefile          |    1
> > > >  fs/fuse/file_iomap.c      |  434 +++++++++++++++++++++++++++++++++++++++++++++
> > > >  fs/fuse/inode.c           |    9 +
> > > >  7 files changed, 636 insertions(+), 1 deletion(-)
> > > >  create mode 100644 fs/fuse/iomap_priv.h
> > > >  create mode 100644 fs/fuse/file_iomap.c
> > > >
> > > > new file mode 100644
> > > > index 00000000000000..243d92cb625095
> > > > --- /dev/null
> > > > +++ b/fs/fuse/iomap_priv.h
> > > > @@ -0,0 +1,36 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> > > > + * Author: Darrick J. Wong <djwong@kernel.org>
> > > > + */
> > > > +#ifndef _FS_FUSE_IOMAP_PRIV_H
> > > > +#define _FS_FUSE_IOMAP_PRIV_H
> > > > +
> > > ...
> > > > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > > > index 31b80f93211b81..3634cbe602cd9c 100644
> > > > --- a/include/uapi/linux/fuse.h
> > > > +++ b/include/uapi/linux/fuse.h
> > > > @@ -235,6 +235,9 @@
> > > >   *
> > > >   *  7.44
> > > >   *  - add FUSE_NOTIFY_INC_EPOCH
> > > > + *
> > > > + *  7.99
> > >
> > > Just curious, where did you get the .99 from?
> >
> > Any time I go adding to a versioned ABI, I try to use high numbers (and
> > high bits for flags) so that it's really obvious that the new flags are
> > in use when I poke through crash/gdb/etc.
> >
> > For permanent artifacts like an ondisk format, it's convenient to cache
> > fs images for fuzz testing, etc.  Using a high bit/number reduces the
> > chance that someone else's new feature will get merged and cause
> > conflicts, which force me to regenerate all cached images.
> >
> > Obviously at merge time I change these values to use lower bit positions
> > or version numbers to fit the merge target so it doesn't completely
> > eliminate the caching problems.
> 
> Ahh okay I see, thanks for the explanation!
> 
> >
> > > > + *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
> > > >   */
> > > >
> > > >  #ifndef _LINUX_FUSE_H
> > > > @@ -270,7 +273,7 @@
> > > >  #define FUSE_KERNEL_VERSION 7
> > > > diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> > > > index 9563fa5387a241..67dfe300bf2e07 100644
> > > > --- a/fs/fuse/Kconfig
> > > > +++ b/fs/fuse/Kconfig
> > > > @@ -69,6 +69,38 @@ config FUSE_PASSTHROUGH
> > > > +config FUSE_IOMAP_DEBUG
> > > > +       bool "Debug FUSE file IO over iomap"
> > > > +       default n
> > > > +       depends on FUSE_IOMAP
> > > > +       help
> > > > +         Enable debugging assertions for the fuse iomap code paths and logging
> > > > +         of bad iomap file mapping data being sent to the kernel.
> > > > +
> > >
> > > I wonder if we should have a general FUSE_DEBUG that this would fall
> > > under instead of creating one that's iomap_debug specific
> >
> > Probably, but I was also trying to keep this as localized to iomap as
> > possible.  If Miklos would rather I extend it to all of fuse (which is
> > probably a good idea!) then I'm happy to do so.
> >
> > > >  config FUSE_IO_URING
> > > >         bool "FUSE communication over io-uring"
> > > >         default y
> > > > diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
> > > > index 46041228e5be2c..27be39317701d6 100644
> > > > --- a/fs/fuse/Makefile
> > > > +++ b/fs/fuse/Makefile
> > > > @@ -18,5 +18,6 @@ fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
> > > >  fuse-$(CONFIG_FUSE_BACKING) += backing.o
> > > >  fuse-$(CONFIG_SYSCTL) += sysctl.o
> > > >  fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
> > > > +fuse-$(CONFIG_FUSE_IOMAP) += file_iomap.o
> > > >
> > > >  virtiofs-y := virtio_fs.o
> > > > diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> > > > new file mode 100644
> > > > index 00000000000000..dda757768d3ea6
> > > > --- /dev/null
> > > > +++ b/fs/fuse/file_iomap.c
> > > > @@ -0,0 +1,434 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> > > > + * Author: Darrick J. Wong <djwong@kernel.org>
> > > > + */
> > > > +#include <linux/iomap.h>
> > > > +#include "fuse_i.h"
> > > > +#include "fuse_trace.h"
> > > > +#include "iomap_priv.h"
> > > > +
> > > > +/* Validate FUSE_IOMAP_TYPE_* */
> > > > +static inline bool fuse_iomap_check_type(uint16_t fuse_type)
> > > > +{
> > > > +       switch (fuse_type) {
> > > > +       case FUSE_IOMAP_TYPE_HOLE:
> > > > +       case FUSE_IOMAP_TYPE_DELALLOC:
> > > > +       case FUSE_IOMAP_TYPE_MAPPED:
> > > > +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> > > > +       case FUSE_IOMAP_TYPE_INLINE:
> > > > +       case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
> > > > +               return true;
> > > > +       }
> > > > +
> > > > +       return false;
> > > > +}
> > >
> > > Maybe faster to check by using a bitmask instead?
> >
> > They're consecutive; one could #define a FUSE_IOMAP_TYPE_MAX to alias
> > PURE_OVERWRITE and collapse the whole check to:
> >
> >         return fuse_type <= FUSE_IOMAP_TYPE_MAX;
> >
> > > > +
> > > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > > > index 1e7298b2b89b58..32f4b7c9a20a8a 100644
> > > > --- a/fs/fuse/inode.c
> > > > +++ b/fs/fuse/inode.c
> > > > @@ -1448,6 +1448,13 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
> > > >
> > > >                         if (flags & FUSE_REQUEST_TIMEOUT)
> > > >                                 timeout = arg->request_timeout;
> > > > +
> > > > +                       if ((flags & FUSE_IOMAP) && fuse_iomap_enabled()) {
> > > > +                               fc->local_fs = 1;
> > > > +                               fc->iomap = 1;
> > > > +                               printk(KERN_WARNING
> > > > + "fuse: EXPERIMENTAL iomap feature enabled.  Use at your own risk!");
> > > > +                       }
> > >
> > > pr_warn() seems to be the convention elsewhere in the fuse code
> >
> > Ah, thanks.  Do you know why fuse calls pr_warn("fuse: XXX") instead of
> > the usual sequence of
> >
> > #define pr_fmt(fmt) "fuse: " fmt
> >
> > so that "fuse: " gets included automatically?
> 
> I think it does do this, or at least that's what I see in fuse_i.h :D

Whoooops, sorry for the noise :)

--D

> Thanks,
> Joanne
> >
> > --D
> >
> > >
> > > Thanks,
> > > Joanne
> > > >                 } else {
> > > >                         ra_pages = fc->max_read / PAGE_SIZE;
> > > >                         fc->no_lock = 1;
> > > > @@ -1516,6 +1523,8 @@ static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
> > > >          */
> > > >         if (fuse_uring_enabled())
> > > >                 flags |= FUSE_OVER_IO_URING;
> > > > +       if (fuse_iomap_enabled())
> > > > +               flags |= FUSE_IOMAP;
> > > >
> > > >         ia->in.flags = flags;
> > > >         ia->in.flags2 = flags >> 32;
> > > >
> > >

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Darrick J. Wong]

On Tue, Sep 23, 2025 at 01:59:36PM -0700, Darrick J. Wong wrote:
> On Tue, Sep 23, 2025 at 08:56:47PM +0200, Miklos Szeredi wrote:
> > On Tue, 23 Sept 2025 at 16:54, Darrick J. Wong <djwong@kernel.org> wrote:
> > 
> > > I'm not sure what you're referring to by "special" -- are you asking
> > > about why I added the touch_softlockup_watchdog() call here but not in
> > > fuse_wait_aborted()?  I think it could use that treatment too, but once
> > > you abort all the pending requests they tend to go away very quickly.
> > > It might be the case that nobody's gotten a warning simply because the
> > > aborted requests all go away in under 30 seconds.
> > 
> > Maybe I'm not understanding how the softlockup detector works.  I
> > thought that it triggers if task is spinning in a tight loop.  That
> > precludes any timeouts, since that means that the task went to sleep.
> > 
> > So what's happening here?
> 
> Hrm, I thought the softlockup detector also complains about tasks stuck
> in uninterruptible sleep, but you're right, it *does* schedule() so the
> softlockup detector won't complain about it.
> 
> I think.  Let me go try to prove that empirically. :)

Hrm.  If I change the bottom of the function to:

wait_event(fc->blocked_waitq, <some false expression>);

Then I get softlockup warnings because the process state gets set to
UNINTERRUPTIBLE, schedule() is called to pick another process, and the
umount process never reaches runnable state ever again.

If instead I change it to:

while (wait_event_timeout(fc->blocked_waitq, <false expr>, HZ) == 0) {
	/* empty */
}

then I do not get softlockup warnings, because the umount process
actually does get scheduled off and on the system, repeatedly.

Conclusion: The loop is necessary to avoid softlockup warnings while the
fuse requests are processed by the server, but it is not necessary to
touch the watchdog in the loop body.

Thanks for challenging me, now I've learned something useful. :)

--D

Re: [PATCH 01/28] fuse: implement the basic iomap mechanisms

[Darrick J. Wong]

On Tue, Sep 23, 2025 at 03:10:14PM -0700, Darrick J. Wong wrote:
> On Tue, Sep 23, 2025 at 02:24:21PM -0700, Joanne Koong wrote:
> > On Tue, Sep 23, 2025 at 1:32 PM Darrick J. Wong <djwong@kernel.org> wrote:
> > >
> > > On Fri, Sep 19, 2025 at 03:36:52PM -0700, Joanne Koong wrote:
> > > > On Mon, Sep 15, 2025 at 5:28 PM Darrick J. Wong <djwong@kernel.org> wrote:
> > > > >
> > > > > From: Darrick J. Wong <djwong@kernel.org>
> > > > >
> > > > > Implement functions to enable upcalling of iomap_begin and iomap_end to
> > > > > userspace fuse servers.
> > > > >
> > > > > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > > > > ---
> > > > >  fs/fuse/fuse_i.h          |   35 ++++
> > > > >  fs/fuse/iomap_priv.h      |   36 ++++
> > > > >  include/uapi/linux/fuse.h |   90 +++++++++
> > > > >  fs/fuse/Kconfig           |   32 +++
> > > > >  fs/fuse/Makefile          |    1
> > > > >  fs/fuse/file_iomap.c      |  434 +++++++++++++++++++++++++++++++++++++++++++++
> > > > >  fs/fuse/inode.c           |    9 +
> > > > >  7 files changed, 636 insertions(+), 1 deletion(-)
> > > > >  create mode 100644 fs/fuse/iomap_priv.h
> > > > >  create mode 100644 fs/fuse/file_iomap.c
> > > > >
> > > > > new file mode 100644
> > > > > index 00000000000000..243d92cb625095
> > > > > --- /dev/null
> > > > > +++ b/fs/fuse/iomap_priv.h
> > > > > @@ -0,0 +1,36 @@
> > > > > +// SPDX-License-Identifier: GPL-2.0
> > > > > +/*
> > > > > + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> > > > > + * Author: Darrick J. Wong <djwong@kernel.org>
> > > > > + */
> > > > > +#ifndef _FS_FUSE_IOMAP_PRIV_H
> > > > > +#define _FS_FUSE_IOMAP_PRIV_H
> > > > > +
> > > > ...
> > > > > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > > > > index 31b80f93211b81..3634cbe602cd9c 100644
> > > > > --- a/include/uapi/linux/fuse.h
> > > > > +++ b/include/uapi/linux/fuse.h
> > > > > @@ -235,6 +235,9 @@
> > > > >   *
> > > > >   *  7.44
> > > > >   *  - add FUSE_NOTIFY_INC_EPOCH
> > > > > + *
> > > > > + *  7.99
> > > >
> > > > Just curious, where did you get the .99 from?
> > >
> > > Any time I go adding to a versioned ABI, I try to use high numbers (and
> > > high bits for flags) so that it's really obvious that the new flags are
> > > in use when I poke through crash/gdb/etc.
> > >
> > > For permanent artifacts like an ondisk format, it's convenient to cache
> > > fs images for fuzz testing, etc.  Using a high bit/number reduces the
> > > chance that someone else's new feature will get merged and cause
> > > conflicts, which force me to regenerate all cached images.
> > >
> > > Obviously at merge time I change these values to use lower bit positions
> > > or version numbers to fit the merge target so it doesn't completely
> > > eliminate the caching problems.
> > 
> > Ahh okay I see, thanks for the explanation!
> > 
> > >
> > > > > + *  - add FUSE_IOMAP and iomap_{begin,end,ioend} for regular file operations
> > > > >   */
> > > > >
> > > > >  #ifndef _LINUX_FUSE_H
> > > > > @@ -270,7 +273,7 @@
> > > > >  #define FUSE_KERNEL_VERSION 7
> > > > > diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> > > > > index 9563fa5387a241..67dfe300bf2e07 100644
> > > > > --- a/fs/fuse/Kconfig
> > > > > +++ b/fs/fuse/Kconfig
> > > > > @@ -69,6 +69,38 @@ config FUSE_PASSTHROUGH
> > > > > +config FUSE_IOMAP_DEBUG
> > > > > +       bool "Debug FUSE file IO over iomap"
> > > > > +       default n
> > > > > +       depends on FUSE_IOMAP
> > > > > +       help
> > > > > +         Enable debugging assertions for the fuse iomap code paths and logging
> > > > > +         of bad iomap file mapping data being sent to the kernel.
> > > > > +
> > > >
> > > > I wonder if we should have a general FUSE_DEBUG that this would fall
> > > > under instead of creating one that's iomap_debug specific
> > >
> > > Probably, but I was also trying to keep this as localized to iomap as
> > > possible.  If Miklos would rather I extend it to all of fuse (which is
> > > probably a good idea!) then I'm happy to do so.
> > >
> > > > >  config FUSE_IO_URING
> > > > >         bool "FUSE communication over io-uring"
> > > > >         default y
> > > > > diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
> > > > > index 46041228e5be2c..27be39317701d6 100644
> > > > > --- a/fs/fuse/Makefile
> > > > > +++ b/fs/fuse/Makefile
> > > > > @@ -18,5 +18,6 @@ fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
> > > > >  fuse-$(CONFIG_FUSE_BACKING) += backing.o
> > > > >  fuse-$(CONFIG_SYSCTL) += sysctl.o
> > > > >  fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
> > > > > +fuse-$(CONFIG_FUSE_IOMAP) += file_iomap.o
> > > > >
> > > > >  virtiofs-y := virtio_fs.o
> > > > > diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
> > > > > new file mode 100644
> > > > > index 00000000000000..dda757768d3ea6
> > > > > --- /dev/null
> > > > > +++ b/fs/fuse/file_iomap.c
> > > > > @@ -0,0 +1,434 @@
> > > > > +// SPDX-License-Identifier: GPL-2.0
> > > > > +/*
> > > > > + * Copyright (C) 2025 Oracle.  All Rights Reserved.
> > > > > + * Author: Darrick J. Wong <djwong@kernel.org>
> > > > > + */
> > > > > +#include <linux/iomap.h>
> > > > > +#include "fuse_i.h"
> > > > > +#include "fuse_trace.h"
> > > > > +#include "iomap_priv.h"
> > > > > +
> > > > > +/* Validate FUSE_IOMAP_TYPE_* */
> > > > > +static inline bool fuse_iomap_check_type(uint16_t fuse_type)
> > > > > +{
> > > > > +       switch (fuse_type) {
> > > > > +       case FUSE_IOMAP_TYPE_HOLE:
> > > > > +       case FUSE_IOMAP_TYPE_DELALLOC:
> > > > > +       case FUSE_IOMAP_TYPE_MAPPED:
> > > > > +       case FUSE_IOMAP_TYPE_UNWRITTEN:
> > > > > +       case FUSE_IOMAP_TYPE_INLINE:
> > > > > +       case FUSE_IOMAP_TYPE_PURE_OVERWRITE:
> > > > > +               return true;
> > > > > +       }
> > > > > +
> > > > > +       return false;
> > > > > +}
> > > >
> > > > Maybe faster to check by using a bitmask instead?
> > >
> > > They're consecutive; one could #define a FUSE_IOMAP_TYPE_MAX to alias
> > > PURE_OVERWRITE and collapse the whole check to:
> > >
> > >         return fuse_type <= FUSE_IOMAP_TYPE_MAX;

I godbolted this with gcc -O0, and got (arm64):

        sub     sp, sp, #16
        strh    w0, [sp, 14]
        ldrh    w0, [sp, 14]	/* load first arg in w0 */
        cmp     w0, 4
        bgt     .L2		/* goto L2 if arg > _INLINE */
        cmp     w0, 0
        bge     .L3		/* goto L3 if _HOLE <= arg <= _INLINE */
        b       .L4		/* goto L4 if arg < _HOLE */
.L2:
        cmp     w0, 255		/* goto L4 if arg != _PURE_OVERWRITE */
        bne     .L4
.L3:
        mov     w0, 1		/* input was good */
        b       .L5
.L4:
        mov     w0, 0		/* input was bad */
.L5:				/* return result in w0 */
        add     sp, sp, 16
        ret

The compiler is apparently smart enough to recognize the adjacent case
statements and merge them into the appropriate integer comparisons.

--D

> > >
> > > > > +
> > > > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > > > > index 1e7298b2b89b58..32f4b7c9a20a8a 100644
> > > > > --- a/fs/fuse/inode.c
> > > > > +++ b/fs/fuse/inode.c
> > > > > @@ -1448,6 +1448,13 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
> > > > >
> > > > >                         if (flags & FUSE_REQUEST_TIMEOUT)
> > > > >                                 timeout = arg->request_timeout;
> > > > > +
> > > > > +                       if ((flags & FUSE_IOMAP) && fuse_iomap_enabled()) {
> > > > > +                               fc->local_fs = 1;
> > > > > +                               fc->iomap = 1;
> > > > > +                               printk(KERN_WARNING
> > > > > + "fuse: EXPERIMENTAL iomap feature enabled.  Use at your own risk!");
> > > > > +                       }
> > > >
> > > > pr_warn() seems to be the convention elsewhere in the fuse code
> > >
> > > Ah, thanks.  Do you know why fuse calls pr_warn("fuse: XXX") instead of
> > > the usual sequence of
> > >
> > > #define pr_fmt(fmt) "fuse: " fmt
> > >
> > > so that "fuse: " gets included automatically?
> > 
> > I think it does do this, or at least that's what I see in fuse_i.h :D
> 
> Whoooops, sorry for the noise :)
> 
> --D
> 
> > Thanks,
> > Joanne
> > >
> > > --D
> > >
> > > >
> > > > Thanks,
> > > > Joanne
> > > > >                 } else {
> > > > >                         ra_pages = fc->max_read / PAGE_SIZE;
> > > > >                         fc->no_lock = 1;
> > > > > @@ -1516,6 +1523,8 @@ static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
> > > > >          */
> > > > >         if (fuse_uring_enabled())
> > > > >                 flags |= FUSE_OVER_IO_URING;
> > > > > +       if (fuse_iomap_enabled())
> > > > > +               flags |= FUSE_IOMAP;
> > > > >
> > > > >         ia->in.flags = flags;
> > > > >         ia->in.flags2 = flags >> 32;
> > > > >
> > > >
> 

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Miklos Szeredi]

On Wed, 24 Sept 2025 at 00:34, Darrick J. Wong <djwong@kernel.org> wrote:

> Conclusion: The loop is necessary to avoid softlockup warnings while the
> fuse requests are processed by the server, but it is not necessary to
> touch the watchdog in the loop body.

I'm still confused.

What is the kernel message you get?

"watchdog: BUG: soft lockup - CPU#X stuck for NNs!"

or

"INFO: task PROC blocked for more than NN seconds."

Thanks,
Miklos

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Miklos Szeredi]

On Tue, 23 Sept 2025 at 22:51, Darrick J. Wong <djwong@kernel.org> wrote:

> Oh, ok.  I can do that.  Just to be clear about what I need to do for
> v6:
>
> * fuse_conn::is_local goes away
> * FUSE_I_* gains a new FUSE_I_EXCLUSIVE flag
> * "local" operations check for FUSE_I_EXCLUSIVE instead of local_fs
> * fuseblk filesystems always set FUSE_I_EXCLUSIVE

Not sure if we want to touch fuseblk, as that carries a risk of regressions.

> * iomap filesystems (when they arrive) always set FUSE_I_EXCLUSIVE

Yes.

Thanks,
Miklos

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Darrick J. Wong]

On Wed, Sep 24, 2025 at 03:55:48PM +0200, Miklos Szeredi wrote:
> On Tue, 23 Sept 2025 at 22:51, Darrick J. Wong <djwong@kernel.org> wrote:
> 
> > Oh, ok.  I can do that.  Just to be clear about what I need to do for
> > v6:
> >
> > * fuse_conn::is_local goes away
> > * FUSE_I_* gains a new FUSE_I_EXCLUSIVE flag
> > * "local" operations check for FUSE_I_EXCLUSIVE instead of local_fs
> > * fuseblk filesystems always set FUSE_I_EXCLUSIVE
> 
> Not sure if we want to touch fuseblk, as that carries a risk of regressions.

Hrm.  As it stands today, setting FUSE_I_EXCLUSIVE in fuseblk mode
solves various mode/acl failures in fstests.

On the other hand, mounting with fuseblk requires fsname to point to a
block device that the mount()ing process can open, and if you're working
with a local filesystem on a block device, why wouldn't you use iomap
mode?

Add to that Ted's reluctance to merge the fuseblk support patches into
fuse2fs, and perhaps I should take that as a sign to abandon fuseblk
work entirely.  It'd get rid of an entire test configuration, since I'd
only have to check fuse4fs-iomap on a bdev; and classic fuse4fs on a
regular file.  Even in that second case, fuse4fs could losetup to take
advantage of iomap mode.

Yeah ok I've persuaded myself to drop the fuseblk stuff entirely.  If
anyone /really/ wants me to keep it, holler in the next couple of hours.

> > * iomap filesystems (when they arrive) always set FUSE_I_EXCLUSIVE
> 
> Yes.

Ok, thanks for the quick responses! :)

--D

> Thanks,
> Miklos

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Darrick J. Wong]

On Wed, Sep 24, 2025 at 02:04:20PM +0200, Miklos Szeredi wrote:
> On Wed, 24 Sept 2025 at 00:34, Darrick J. Wong <djwong@kernel.org> wrote:
> 
> > Conclusion: The loop is necessary to avoid softlockup warnings while the
> > fuse requests are processed by the server, but it is not necessary to
> > touch the watchdog in the loop body.
> 
> I'm still confused.
> 
> What is the kernel message you get?
> 
> "watchdog: BUG: soft lockup - CPU#X stuck for NNs!"
> 
> or
> 
> "INFO: task PROC blocked for more than NN seconds."

Oh!  The second:

INFO: task umount:1279 blocked for more than 20 seconds.
      Not tainted 6.17.0-rc7-xfsx #rc7
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this messag.
task:umount          state:D stack:11984 pid:1279  tgid:1279  ppid:10690
Call Trace:
 <TASK>
 __schedule+0x4cb/0x1a70
 ? vprintk_emit+0x10e/0x330
 schedule+0x2a/0xe0
 fuse_flush_requests_and_wait+0xe5/0x110 [fuse 810ab4024704e943aea18e16]
 ? cpuacct_css_alloc+0xa0/0xa0
 fuse_iomap_unmount+0x15/0x30 [fuse 810ab4024704e943aea18e1670e01b473ed]
 fuse_conn_destroy+0xdb/0xe0 [fuse 810ab4024704e943aea18e1670e01b473ed1]
 fuse_kill_sb_anon+0xb7/0xc0 [fuse 810ab4024704e943aea18e1670e01b473ed1]
 deactivate_locked_super+0x29/0xa0
 cleanup_mnt+0xbd/0x150
 task_work_run+0x55/0x90
 exit_to_user_mode_loop+0xa0/0xb0
 do_syscall_64+0x16b/0x1a0
 entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7f24c342ab77
RSP: 002b:00007ffd683ce5e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00005648fc1208a8 RCX: 00007f24c342ab77
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00005648fc1209c0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000073
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f24c3566264
R13: 00005648fc1209c0 R14: 0000000000000000 R15: 00005648fc120790
 </TASK>

Apologies for my imprecise description of what I was trying to avoid; I
should have paid closer attention.

The wait_event_timeout() loop causes the process to schedule at least
once per second, which avoids the "blocked for more than..." warning.
Since the process actually does go to sleep, it's not necessary to touch
the softlockup watchdog because we're not preventing another process
from being scheduled on a CPU.

I can copy the above into the commit message if that resolves the
confusion.

--D

> Thanks,
> Miklos

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Miklos Szeredi]

On Wed, 24 Sept 2025 at 19:50, Darrick J. Wong <djwong@kernel.org> wrote:

> The wait_event_timeout() loop causes the process to schedule at least
> once per second, which avoids the "blocked for more than..." warning.
> Since the process actually does go to sleep, it's not necessary to touch
> the softlockup watchdog because we're not preventing another process
> from being scheduled on a CPU.

To be clear, this triggers because no RELEASE reply is received for
more than 20 seconds?  That sounds weird.  What is the server doing
all that time?

If a reply *is* received, then the task doing the umount should have
woken up (to check fc->num_waiting), which would have prevented the
hung task warning.

What am I missing?

Thanks,
Miklos

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Darrick J. Wong]

On Wed, Sep 24, 2025 at 08:19:59PM +0200, Miklos Szeredi wrote:
> On Wed, 24 Sept 2025 at 19:50, Darrick J. Wong <djwong@kernel.org> wrote:
> 
> > The wait_event_timeout() loop causes the process to schedule at least
> > once per second, which avoids the "blocked for more than..." warning.
> > Since the process actually does go to sleep, it's not necessary to touch
> > the softlockup watchdog because we're not preventing another process
> > from being scheduled on a CPU.
> 
> To be clear, this triggers because no RELEASE reply is received for
> more than 20 seconds?  That sounds weird.  What is the server doing
> all that time?
> 
> If a reply *is* received, then the task doing the umount should have
> woken up (to check fc->num_waiting), which would have prevented the
> hung task warning.
> 
> What am I missing?

(Note: I set /proc/sys/kernel/hung_task_timeout_secs to 10 seconds to
generate the 20 second warning)

I think what you're missing is the fuse server taking more than 20
seconds to process one RELEASE command successfully.  Say you create a
sparse file with 1 million extents, open it, and unlink the the file.
The file's still open, so the unlink can't truncate it or free it.

Next, you close the file and unmount the filesystem.  Inode eviction
causes a RELEASE command to be issued, so the fuse server starts
truncating the file to free it.  There's a million extents to free, but
the server is slow and can't process more than (say) 1000 extent freeing
operations per second.  That implies that the truncation will take 1000
seconds to complete, which means the reply to the RELEASE doesn't arrive
for 1000 seconds.  Meanwhile, the umount process doesn't see a change in
fc->waiting for 1000 seconds, so it isn't woken up for that amount of
time and we get the stuck task warning.

I think we don't want stuck task warnings because the "stuck" task
(umount) is not the task that is actually doing the work.  For an
in-kernel filesystem like XFS, the inode eviction process would be
generating enough context switches from all the metadata IOs to avoid
the hung task warning.

--D

> Thanks,
> Miklos
> 

Re: [PATCH 2/5] fuse: move the backing file idr and code into a new source file

[Miklos Szeredi]

On Tue, 16 Sept 2025 at 02:27, Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> iomap support for fuse is also going to want the ability to attach
> backing files to a fuse filesystem.  Move the fuse_backing code into a
> separate file so that both can use it.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>

Applied, thanks.

Miklos

Re: [PATCH 5/5] fuse: move CREATE_TRACE_POINTS to a separate file

[Miklos Szeredi]

On Tue, 16 Sept 2025 at 02:27, Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> Before we start adding new tracepoints for fuse+iomap, move the
> tracepoint creation itself to a separate source file so that we don't
> have to start pulling iomap dependencies into dev.c just for the iomap
> structures.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

Applied, thanks.
Miklos

Re: [PATCH 4/8] fuse: signal that a fuse filesystem should exhibit local fs behaviors

[Darrick J. Wong]

On Wed, Sep 24, 2025 at 10:31:36AM -0700, Darrick J. Wong wrote:
> On Wed, Sep 24, 2025 at 03:55:48PM +0200, Miklos Szeredi wrote:
> > On Tue, 23 Sept 2025 at 22:51, Darrick J. Wong <djwong@kernel.org> wrote:
> > 
> > > Oh, ok.  I can do that.  Just to be clear about what I need to do for
> > > v6:
> > >
> > > * fuse_conn::is_local goes away
> > > * FUSE_I_* gains a new FUSE_I_EXCLUSIVE flag
> > > * "local" operations check for FUSE_I_EXCLUSIVE instead of local_fs
> > > * fuseblk filesystems always set FUSE_I_EXCLUSIVE
> > 
> > Not sure if we want to touch fuseblk, as that carries a risk of regressions.
> 
> Hrm.  As it stands today, setting FUSE_I_EXCLUSIVE in fuseblk mode
> solves various mode/acl failures in fstests.
> 
> On the other hand, mounting with fuseblk requires fsname to point to a
> block device that the mount()ing process can open, and if you're working
> with a local filesystem on a block device, why wouldn't you use iomap
> mode?
> 
> Add to that Ted's reluctance to merge the fuseblk support patches into
> fuse2fs, and perhaps I should take that as a sign to abandon fuseblk
> work entirely.  It'd get rid of an entire test configuration, since I'd
> only have to check fuse4fs-iomap on a bdev; and classic fuse4fs on a
> regular file.  Even in that second case, fuse4fs could losetup to take
> advantage of iomap mode.
> 
> Yeah ok I've persuaded myself to drop the fuseblk stuff entirely.  If
> anyone /really/ wants me to keep it, holler in the next couple of hours.

Ted agrees with this, so I'm dropping fuseblk support for fuse[24]fs.

--D

> > > * iomap filesystems (when they arrive) always set FUSE_I_EXCLUSIVE
> > 
> > Yes.
> 
> Ok, thanks for the quick responses! :)
> 
> --D
> 
> > Thanks,
> > Miklos
> 

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Miklos Szeredi]

On Wed, 24 Sept 2025 at 22:54, Darrick J. Wong <djwong@kernel.org> wrote:

> I think we don't want stuck task warnings because the "stuck" task
> (umount) is not the task that is actually doing the work.

Agreed.

I do wonder why this isn't happening during normal operation.  There
could be multiple explanations:

 - release is async, so this particular case would not trigger the hang warning

 - some other op could be taking a long time to complete (fsync?), but
request_wait_answer() starts with interruptible sleep and falls back
to uninterruptible sleep after a signal is received.  So unless
there's a signal, even a very slow request would fail to trigger the
hang warning.

A more generic solution would be to introduce a mechanism that would
tell the kernel that while the request is taking long, it's not
stalled (e.g. periodic progress reports).

But I also get the feeling that this is not very urgent and possibly
more of a test checkbox than a real life issue.

Thanks,
Miklos

Re: [PATCH 2/8] fuse: flush pending fuse events before aborting the connection

[Darrick J. Wong]

On Tue, Sep 30, 2025 at 12:29:30PM +0200, Miklos Szeredi wrote:
> On Wed, 24 Sept 2025 at 22:54, Darrick J. Wong <djwong@kernel.org> wrote:
> 
> > I think we don't want stuck task warnings because the "stuck" task
> > (umount) is not the task that is actually doing the work.
> 
> Agreed.
> 
> I do wonder why this isn't happening during normal operation.  There
> could be multiple explanations:
> 
>  - release is async, so this particular case would not trigger the hang warning

<nod> I confirm that a normal release takes place asynchronously, so
nothing in the kernel gets hung up if ->release takes a long time.

It's only my new code that causes the hang warnings, and only because
it's using the non-interruptible wait_event variant to flush the
requests.

(I /could/ solve the problem differently by calling
wait_event_interruptible in a loop and ignoring the EINTR, but that
seems like a misuse of APIs.)

>  - some other op could be taking a long time to complete (fsync?), but
> request_wait_answer() starts with interruptible sleep and falls back
> to uninterruptible sleep after a signal is received.  So unless
> there's a signal, even a very slow request would fail to trigger the
> hang warning.

Yes, that's what happens if I inject a "stall" into, say, fallocate by
adding a gdb breakpoint on the fallocate handler in fuse4fs.  The xfs_io
process calling fallocate() then just blocks in interruptible sleep
and I see no complaints from the hangcheck timer.  But it's fallocate(),
which is quite interruptible.

Unmount is different -- the kernel has already torn down some of the
mount state, so we can't back out after some sort of interruption.

> A more generic solution would be to introduce a mechanism that would
> tell the kernel that while the request is taking long, it's not
> stalled (e.g. periodic progress reports).
> 
> But I also get the feeling that this is not very urgent and possibly
> more of a test checkbox than a real life issue.

It's probably not an issue for 99% of filesystems and use cases, but
unprivileged userspace can set up the conditions for a stall warning.
Some customers file bug reports for /any/ kernel backtrace, even if it's
a stall warning caused by slow IO, so I'd prefer not to create a new
opening for this to happen.

--D

> 
> Thanks,
> Miklos

Re: [PATCH 10/10] libext2fs: add posix advisory locking to the unix IO manager

[Darrick J. Wong]

On Mon, Sep 15, 2025 at 05:58:43PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Add support for using flock() to protect the files opened by the Unix IO
> manager so that we can't mount the same fs multiple times.  This also
> prevents systemd and udev from accessing the device while e2fsprogs is
> doing something with the device.
> 
> Link: https://systemd.io/BLOCK_DEVICE_LOCKING/
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

This actually causes a lot of problems with fstests -- if fuse2fs
flock()s the block device, then udevd will spin in a slow trylock loop
until the bdev can be locked.  Meanwhile, any scripts calling udevadm
settle will block until fuse2fs exits (or it gives up after 2 minutes go
by), because udev still has a uevent that it cannot settle.  This causes
any test that uses udevadm settle to take forever to run.

In general, we don't want to block udev from reading the block device
while fuse2fs has it mounted.  For block devices this is unnecessary
anyway because we have O_EXCL.

However, the advisory locking is still useful for coordinating access to
filesystem images in regular files, so I'll rework this to only do it
for regular files.

--D

> ---
>  lib/ext2fs/unix_io.c |   64 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
> 
> 
> diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
> index 068be689326443..55007ad7d2ae15 100644
> --- a/lib/ext2fs/unix_io.c
> +++ b/lib/ext2fs/unix_io.c
> @@ -65,6 +65,12 @@
>  #include <pthread.h>
>  #endif
>  
> +#if defined(HAVE_SYS_FILE_H) && defined(HAVE_SIGNAL_H)
> +# include <sys/file.h>
> +# include <signal.h>
> +# define WANT_LOCK_UNIX_FD
> +#endif
> +
>  #if defined(__linux__) && defined(_IO) && !defined(BLKROGET)
>  #define BLKROGET   _IO(0x12, 94) /* Get read-only status (0 = read_write).  */
>  #endif
> @@ -149,6 +155,9 @@ struct unix_private_data {
>  	pthread_mutex_t bounce_mutex;
>  	pthread_mutex_t stats_mutex;
>  #endif
> +#ifdef WANT_LOCK_UNIX_FD
> +	int	lock_flags;
> +#endif
>  };
>  
>  #define IS_ALIGNED(n, align) ((((uintptr_t) n) & \
> @@ -897,6 +906,47 @@ int ext2fs_fstat(int fd, ext2fs_struct_stat *buf)
>  #endif
>  }
>  
> +#ifdef WANT_LOCK_UNIX_FD
> +static void unix_lock_alarm_handler(int signal, siginfo_t *data, void *p)
> +{
> +	/* do nothing, the signal will abort the flock operation */
> +}
> +
> +static int unix_lock_fd(int fd, int flags)
> +{
> +	struct sigaction newsa = {
> +		.sa_flags = SA_SIGINFO,
> +		.sa_sigaction = unix_lock_alarm_handler,
> +	};
> +	struct sigaction oldsa;
> +	const int operation = (flags & IO_FLAG_EXCLUSIVE) ? LOCK_EX : LOCK_SH;
> +	int ret;
> +
> +	/* wait five seconds for the lock */
> +	ret = sigaction(SIGALRM, &newsa, &oldsa);
> +	if (ret)
> +		return ret;
> +
> +	alarm(5);
> +
> +	ret = flock(fd, operation);
> +	if (ret == 0)
> +		ret = operation;
> +	else if (errno == EINTR) {
> +		errno = EWOULDBLOCK;
> +		ret = -1;
> +	}
> +
> +	alarm(0);
> +	sigaction(SIGALRM, &oldsa, NULL);
> +	return ret;
> +}
> +
> +static void unix_unlock_fd(int fd)
> +{
> +	flock(fd, LOCK_UN);
> +}
> +#endif
>  
>  static errcode_t unix_open_channel(const char *name, int fd,
>  				   int flags, io_channel *channel,
> @@ -935,6 +985,16 @@ static errcode_t unix_open_channel(const char *name, int fd,
>  	if (retval)
>  		goto cleanup;
>  
> +#ifdef WANT_LOCK_UNIX_FD
> +	if (flags & IO_FLAG_RW) {
> +		data->lock_flags = unix_lock_fd(fd, flags);
> +		if (data->lock_flags < 0) {
> +			retval = errno;
> +			goto cleanup;
> +		}
> +	}
> +#endif
> +
>  	strcpy(io->name, name);
>  	io->private_data = data;
>  	io->block_size = 1024;
> @@ -1200,6 +1260,10 @@ static errcode_t unix_close(io_channel channel)
>  	if (retval2 && !retval)
>  		retval = retval2;
>  
> +#ifdef WANT_LOCK_UNIX_FD
> +	if (data->lock_flags)
> +		unix_unlock_fd(data->dev);
> +#endif
>  	if (close(data->dev) < 0 && !retval)
>  		retval = errno;
>  	free_cache(data);
> 
>