Re: [PATCH RESEND v9 0/9] fs: interface for directly reading/writing compressed data

[Omar Sandoval <osandov@osandov.com>]

On Tue, May 04, 2021 at 10:15:51AM -0700, Omar Sandoval wrote:
> On Mon, Apr 26, 2021 at 12:06:03PM -0700, Omar Sandoval wrote:
> > From: Omar Sandoval <osandov@fb.com>
> > 
> > This series adds an API for reading compressed data on a filesystem
> > without decompressing it as well as support for writing compressed data
> > directly to the filesystem. I have test cases (including fsstress
> > support) and example programs which I'll send up once the dust settles
> > [1].
> > 
> > The main use-case is Btrfs send/receive: currently, when sending data
> > from one compressed filesystem to another, the sending side decompresses
> > the data and the receiving side recompresses it before writing it out.
> > This is wasteful and can be avoided if we can just send and write
> > compressed extents. The patches implementing the send/receive support
> > were sent with the last submission of this series [2].
> > 
> > Patches 1-3 add the VFS support, UAPI, and documentation. Patches 4-7
> > are Btrfs prep patches. Patch 8 adds Btrfs encoded read support and
> > patch 9 adds Btrfs encoded write support.
> > 
> > These patches are based on Dave Sterba's Btrfs misc-next branch [3],
> > which is in turn currently based on v5.12-rc8.
> > 
> > This is a resend of v9 [4], rebased on the latest kdave/misc-next
> > branch.
> > 
> > Omar Sandoval (9):
> >   iov_iter: add copy_struct_from_iter()
> >   fs: add O_ALLOW_ENCODED open flag
> >   fs: add RWF_ENCODED for reading/writing compressed data
> >   btrfs: don't advance offset for compressed bios in
> >     btrfs_csum_one_bio()
> >   btrfs: add ram_bytes and offset to btrfs_ordered_extent
> >   btrfs: support different disk extent size for delalloc
> >   btrfs: optionally extend i_size in cow_file_range_inline()
> >   btrfs: implement RWF_ENCODED reads
> >   btrfs: implement RWF_ENCODED writes
> > 
> > 1: https://github.com/osandov/xfstests/tree/rwf-encoded
> > 2: https://lore.kernel.org/linux-btrfs/cover.1615922753.git.osandov@fb.com/
> > 3: https://github.com/kdave/btrfs-devel/tree/misc-next
> > 4: https://lore.kernel.org/linux-btrfs/cover.1617258892.git.osandov@fb.com/
> > 
> > Omar Sandoval (9):
> >   iov_iter: add copy_struct_from_iter()
> >   fs: add O_ALLOW_ENCODED open flag
> >   fs: add RWF_ENCODED for reading/writing compressed data
> >   btrfs: don't advance offset for compressed bios in
> >     btrfs_csum_one_bio()
> >   btrfs: add ram_bytes and offset to btrfs_ordered_extent
> >   btrfs: support different disk extent size for delalloc
> >   btrfs: optionally extend i_size in cow_file_range_inline()
> >   btrfs: implement RWF_ENCODED reads
> >   btrfs: implement RWF_ENCODED writes
> > 
> >  Documentation/filesystems/encoded_io.rst | 240 ++++++
> >  Documentation/filesystems/index.rst      |   1 +
> >  arch/alpha/include/uapi/asm/fcntl.h      |   1 +
> >  arch/parisc/include/uapi/asm/fcntl.h     |   1 +
> >  arch/sparc/include/uapi/asm/fcntl.h      |   1 +
> >  fs/btrfs/compression.c                   |  12 +-
> >  fs/btrfs/compression.h                   |   6 +-
> >  fs/btrfs/ctree.h                         |   9 +-
> >  fs/btrfs/delalloc-space.c                |  18 +-
> >  fs/btrfs/file-item.c                     |  35 +-
> >  fs/btrfs/file.c                          |  46 +-
> >  fs/btrfs/inode.c                         | 929 +++++++++++++++++++++--
> >  fs/btrfs/ordered-data.c                  | 124 +--
> >  fs/btrfs/ordered-data.h                  |  25 +-
> >  fs/btrfs/relocation.c                    |   4 +-
> >  fs/fcntl.c                               |  10 +-
> >  fs/namei.c                               |   4 +
> >  fs/read_write.c                          | 168 +++-
> >  include/linux/encoded_io.h               |  17 +
> >  include/linux/fcntl.h                    |   2 +-
> >  include/linux/fs.h                       |  13 +
> >  include/linux/uio.h                      |   1 +
> >  include/uapi/asm-generic/fcntl.h         |   4 +
> >  include/uapi/linux/encoded_io.h          |  30 +
> >  include/uapi/linux/fs.h                  |   5 +-
> >  lib/iov_iter.c                           |  91 +++
> >  26 files changed, 1563 insertions(+), 234 deletions(-)
> >  create mode 100644 Documentation/filesystems/encoded_io.rst
> >  create mode 100644 include/linux/encoded_io.h
> >  create mode 100644 include/uapi/linux/encoded_io.h
> 
> Ping.

Ping. Al, I originally sent v9 over a month ago, and I've been sending
out this series for over a year, so I'd appreciate it if you could take
a look. It's fine if you hate it, but I'd like to know where to go from
here.

Thanks,
Omar