[PATCH 00/24] netfs: Read/write improvements

David Howells
2024-07-29T16:20:27Z

Hi Christian, Steve, Willy,

This set of patches includes one fscache fix and one cachefiles fix

(1) Fix a cookie access race in fscache.

(2) Fix the setxattr/removexattr syscalls to pull their arguments into
kernel space before taking the sb_writers lock to avoid a deadlock
against mm->mmap_lock.

A couple of adjustments to the /proc/fs/netfs/stats file:

(3) All the netfs stats lines begin 'Netfs:'. Change this to something a
bit more useful.

(4) Add a couple of stats counters to track the numbers of skips and waits
on the per-inode writeback serialisation lock to make it easier to
check for this as a source of performance loss.

Some miscellaneous bits:

(5) Reduce the number of conditional branches in netfs_perform_write().

(6) Move the CIFS_INO_MODIFIED_ATTR flag to the netfs_inode struct and
remove cifs_post_modify().

(7) Move the max_len/max_nr_segs members from netfs_io_subrequest to
netfs_io_request as they're only needed for one subreq at a time.

(8) Add an 'unknown' source value for tracing purposes.

(9) Remove NETFS_COPY_TO_CACHE as it's no longer used.

(10) Set the request work function up front at allocation time.

(11) Use bh-disabling spinlocks for rreq->lock as cachefiles completion may
be run from block-filesystem DIO completion in softirq context.

Then there's the main performance enhancing changes:

(12) Define a structure, struct folio_queue, and a new iterator type,
ITER_FOLIOQ, to hold a buffer as a replacement for ITER_XARRAY. See
that patch for questions about naming and form.

(13) Make cifs RDMA support ITER_FOLIOQ.

(14) Add a function to reset the iterator in a subrequest.

(15) Use folio queues in the write-side helpers instead of xarrays.

(16) Simplify the write-side helpers to use sheaves to skip gaps rather than
trying to work out where gaps are.

(17) In afs, make the read subrequests asynchronous, putting them into work
items to allow the next patch to do progressive unlocking/reading.

(18) Overhaul the read-side helpers to improve performance.

(19) Remove fs/netfs/io.c.

(20) Fix the caching of a partial block at the end of a file.

(21) Allow a store to be cancelled.

Then some changes for cifs to make it use folio queues instead of xarrays
for crypto bufferage:

(22) Use raw iteration functions rather than manually coding iteration when
hashing data.

(23) Switch to using folio_queue for crypto buffers.

(24) Remove the xarray bits.

David

David Howells (23):
cachefiles: Fix non-taking of sb_writers around set/removexattr
netfs: Adjust labels in /proc/fs/netfs/stats
netfs: Record contention stats for writeback lock
netfs: Reduce number of conditional branches in netfs_perform_write()
netfs, cifs: Move CIFS_INO_MODIFIED_ATTR to netfs_inode
netfs: Move max_len/max_nr_segs from netfs_io_subrequest to
netfs_io_stream
netfs: Reserve netfs_sreq_source 0 as unset/unknown
netfs: Remove NETFS_COPY_TO_CACHE
netfs: Set the request work function upon allocation
netfs: Use bh-disabling spinlocks for rreq->lock
mm: Define struct folio_queue and ITER_FOLIOQ to handle a sequence of
folios
cifs: Provide the capability to extract from ITER_FOLIOQ to RDMA SGEs
netfs: Use new folio_queue data type and iterator instead of xarray
iter
netfs: Provide an iterator-reset function
netfs: Simplify the writeback code
afs: Make read subreqs async
netfs: Speed up buffered reading
netfs: Remove fs/netfs/io.c
cachefiles, netfs: Fix write to partial block at EOF
netfs: Cancel dirty folios that have no storage destination
cifs: Use iterate_and_advance*() routines directly for hashing
cifs: Switch crypto buffer to use a folio_queue rather than an xarray
cifs: Don't support ITER_XARRAY

Max Kellermann (1):
fs/netfs/fscache_cookie: add missing "n_accesses" check

fs/9p/vfs_addr.c | 5 +-
fs/afs/file.c | 29 +-
fs/afs/fsclient.c | 9 +-
fs/afs/write.c | 4 +-
fs/afs/yfsclient.c | 9 +-
fs/cachefiles/io.c | 19 +-
fs/cachefiles/xattr.c | 34 +-
fs/ceph/addr.c | 72 ++--
fs/netfs/Makefile | 3 +-
fs/netfs/buffered_read.c | 677 ++++++++++++++++++++++++-----------
fs/netfs/buffered_write.c | 309 ++++++++--------
fs/netfs/direct_read.c | 147 +++++++-
fs/netfs/fscache_cookie.c | 4 +
fs/netfs/internal.h | 33 +-
fs/netfs/io.c | 647 ---------------------------------
fs/netfs/iterator.c | 50 +++
fs/netfs/main.c | 6 +-
fs/netfs/misc.c | 94 +++++
fs/netfs/objects.c | 16 +-
fs/netfs/read_collect.c | 540 ++++++++++++++++++++++++++++
fs/netfs/read_retry.c | 256 +++++++++++++
fs/netfs/stats.c | 23 +-
fs/netfs/write_collect.c | 243 ++++---------
fs/netfs/write_issue.c | 92 ++---
fs/nfs/fscache.c | 19 +-
fs/nfs/fscache.h | 7 +-
fs/smb/client/cifsencrypt.c | 144 +-------
fs/smb/client/cifsglob.h | 3 +-
fs/smb/client/cifssmb.c | 6 +-
fs/smb/client/file.c | 71 ++--
fs/smb/client/smb2ops.c | 218 ++++++-----
fs/smb/client/smb2pdu.c | 10 +-
fs/smb/client/smbdirect.c | 82 +++--
include/linux/folio_queue.h | 138 +++++++
include/linux/iov_iter.h | 104 ++++++
include/linux/netfs.h | 44 ++-
include/linux/uio.h | 18 +
include/trace/events/netfs.h | 140 ++++++--
lib/iov_iter.c | 229 +++++++++++-
lib/kunit_iov_iter.c | 259 ++++++++++++++
lib/scatterlist.c | 69 +++-
41 files changed, 3175 insertions(+), 1707 deletions(-)
delete mode 100644 fs/netfs/io.c
create mode 100644 fs/netfs/read_collect.c
create mode 100644 fs/netfs/read_retry.c
create mode 100644 include/linux/folio_queue.h