linux.git/fs/netfs, branch master

netfs: Fix barriering when walking subrequest list

2026-07-03T09:52:41+00:00

Fix the barriering used when walking the subrequest list in retry as
there's a possibility of seeing a subreq that's just been added by the
application thread.

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Fixes: 288ace2f57c9 ("netfs: New writeback implementation")
Link: https://sashiko.dev/#/patchset/20260608145432.681865-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/138807.1782980582@warthog.procyon.org.uk
Reviewed-by: Paulo Alcantara (Red Hat) 
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: Fix DIO write retry for filesystems without a ->prepare_write()

2026-07-01T13:26:30+00:00

Fix netfs_unbuffered_write() so that it doesn't re-issue a write twice when
the filesystem doesn't have a ->prepare_write().  The resetting of the
iterator and the call to netfs_reissue_write() should just be removed as
almost everything it does is done again when the loop it's in goes back to
the top.

It does, however, still need the IN_PROGRESS flag setting, so that (and the
stat inc) are moved out of the if-statement.

Further, the MADE_PROGRESS flags should be cleared and wreq->transferred
should be updated, so fix those too.

Reported-by: syzbot+3c74b1f0c372e98efc32@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3c74b1f0c372e98efc32
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260625140640.3116900-16-dhowells@redhat.com
cc: Paulo Alcantara 
cc: hongao 
cc: ChenXiaoSong 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: Fix folio state after ENOMEM whilst under writeback iteration

2026-07-01T13:26:30+00:00

Fix the state of the current folio when ENOMEM occurs during writeback
iteration.  The folio needs to be redirtied and unlocked before the
terminal writeback_iter() is invoked.

Fixes: 06fa229ceb36 ("netfs: Abstract out a rolling folio buffer implementation")
Link: https://sashiko.dev/#/patchset/20260619140646.2633762-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260625140640.3116900-15-dhowells@redhat.com
cc: Paulo Alcantara 
cc: Matthew Wilcox 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: Fix writeback error handling

2026-07-01T13:26:30+00:00

Fix the error handling in writeback_iter() loop.  If an error occurs,
writeback_iter() needs to be called again with *error set to the error so
that it can clean up iteration state.  Further, the current folio needs
unlocking and redirtying.

Fixes: 288ace2f57c9 ("netfs: New writeback implementation")
Link: https://sashiko.dev/#/patchset/20260619140646.2633762-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260625140640.3116900-14-dhowells@redhat.com
cc: Paulo Alcantara 
cc: Matthew Wilcox 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: Fix writethrough to use collection offload

2026-07-01T13:26:30+00:00

Fix writethrough write to set NETFS_RREQ_OFFLOAD_COLLECTION on the request
so that collection is processed asynchronously rather than only right at
the end - and also so that asynchronous O_SYNC writes get collected at all.

Fixes: 288ace2f57c9 ("netfs: New writeback implementation")
Closes: https://sashiko.dev/#/patchset/20260616100821.2062304-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260625140640.3116900-13-dhowells@redhat.com
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: Replace wb_lock with a bit lock for asynchronicity

2026-07-01T13:26:29+00:00

The netfs_inode::wb_lock mutex is used to prevent multiple simultaneous
writebacks from fighting each other (a writeback thread will write multiple
discontiguous regions within the same request).  The mutex, however, only
serialises the issuing of subrequests; it doesn't serialise the collection
of results, and, in particular, the updating of file size information and
fscache populatedness data.

Unfortunately, the mutex cannot be held around the entire process as it has
to be unlocked in the same thread in which it is locked - and we don't want
to hold up the allocator whilst we complete the writeback.

Fix this by replacing the mutex with a bit flag and a list of lock waiters
so that the lock can be dropped in the collector thread after collection is
complete.

Link: https://sashiko.dev/#/patchset/20260608145432.681865-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260625140640.3116900-12-dhowells@redhat.com
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: Fix netfs_create_write_req() to handle async cache object creation

2026-07-01T13:26:28+00:00

netfs_create_write_req() will skip caching if the fscache cookie is
disabled, but this is a problem because async cache object creation might
not have got far enough yet that has been enabled - thereby causing the
call to fscache_begin_write_operation() to be skipped.

Fix this by removing the checks on the cookie and delegating this to
fscache_begin_write_operation().

Fixes: 7b589a9b45ae ("netfs: Fix handling of USE_PGPRIV2 and WRITE_TO_CACHE flags")
Closes: https://sashiko.dev/#/patchset/20260624115737.2964520-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260625140640.3116900-3-dhowells@redhat.com
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: Fix decision whether to disallow write-streaming due to fscache use

2026-07-01T13:26:28+00:00

netfs_perform_write() buffers data by writing it into the pagecache for
later writeback.  If the folio it wants to write to isn't present, it uses
"write streaming" in which is will store partial data in a non-uptodate,
but dirty folio.

However, when fscache is in use, this is a potential problem as writes to
the cache have to be aligned to the cache backend's DIO granularity, and so
netfs_perform_write() attempts to suppress write-streaming in such a case,
requiring the folio content to be fetched first unless the entire folio is
going to be overwritten.  This allows the content to be written to the
cache too.

Unfortunately, the test netfs_perform_write() uses isn't correct because it
doesn't take into account the fact that the object lookup is asynchronous
and farmed off to a work queue, so there's a short window in which the
cache is doing a lookup but the test fails because the answer is undefined.

This can be triggered by the generic/464 xfstest, and causes a warning to
be emitted in cachefiles (in code not yet upstream) because it sees a write
that doesn't have its bounds rounded out to DIO alignment.

Fix this by changing the condition to whether FSCACHE_COOKIE_IS_CACHING is
set on a cookie rather than whether the cookie is marked enabled.  Note
that this is really just a hint as to whether we allow write streaming or
not and no other aspects of the cookie or cache object are accessed.

Also apply the same fix to netfs_write_begin().

Reported-by: Marc Dionne 
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260625140640.3116900-2-dhowells@redhat.com
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs, afs: Fix write skipping in dir/link writepages

2026-05-12T12:42:32+00:00

Fix netfs_write_single() and afs_single_writepages() to better handle a
write that would be skipped due to lock contention and WB_SYNC_NONE by
returning 1 from netfs_write_single() if it skipped and making
afs_single_writepages() skip also.  If a skip occurs, the inode must be
re-marked as the VFS may have cleared the mark.

This is really only theoretical for directories in netfs_write_single() as
the only path to that is through afs_single_writepages() that takes the
->validate_lock around it, thereby serialising it.

Fixes: 6dd80936618c ("afs: Use netfslib for directories")
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260512123404.719402-24-dhowells@redhat.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner

netfs: Fix netfs_read_folio() to wait on writeback

2026-05-12T12:42:32+00:00

Fix netfs_read_folio() to wait for an ongoing writeback to complete so that
it can trust the dirty flag and whatever is attached to folio->private
(folio->private may get cleaned up by the collector before it clears the
writeback flag).

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260512123404.719402-23-dhowells@redhat.com
cc: Paulo Alcantara 
cc: Matthew Wilcox 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner