linux.git/fs/netfs, branch v7.2

netfs: Fix folio_queue ENOMEM in writeback by adding a mempool

2026-07-28T13:42:31+00:00

Fix the handling of folio_queue allocation failure in writeback by adding a
mempool and passing in gfp_t flags to the rolling buffer functions that
allocate memory, using the mempool if gfp != GFP_KERNEL.

This is then extended upwards and the gfp to be used for a request is stored
in the netfs_io_request struct and is then used for both requests and
subrequests, eliminating the sleeping loops there.

The failure caused:

    folio != NULL
    WARNING: fs/netfs/write_issue.c:603 at netfs_writepages+0x883/0xa10 fs/netfs/write_issue.c:603, CPU#3: syz.0.17/5919

Fixes: cd0277ed0c18 ("netfs: Use new folio_queue data type and iterator instead of xarray iter")
Reported-by: syzbot+0da43efa72f88bd3a8af@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=0da43efa72f88bd3a8af
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260727130716.1099906-5-dhowells@redhat.com
Tested-by: syzbot+0da43efa72f88bd3a8af@syzkaller.appspotmail.com
cc: Paulo Alcantara 
cc: Yun Zhou 
cc: Matthew Wilcox 
cc: Christoph Hellwig 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: release readahead folios on iterator preparation failure

2026-07-28T13:42:31+00:00

netfs_prepare_read_iterator() batches readahead folios in put_batch so that
the folio references can be dropped after the I/O iterator has been
prepared.

If rolling_buffer_load_from_ra() fails after earlier folios have been
batched, the function returns immediately and leaves those references held.
Release the batch before returning the error.

Fixes: 06fa229ceb36 ("netfs: Abstract out a rolling folio buffer implementation")
Signed-off-by: Yichong Chen 
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260727130716.1099906-4-dhowells@redhat.com
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: handle single writeback rolling buffer allocation failure

2026-07-28T13:42:31+00:00

netfs_write_folio_single() takes an extra folio reference before
appending the folio to the rolling buffer.

rolling_buffer_append() can fail if it cannot allocate another
folio_queue. Check the return value and drop the extra folio reference
before returning the error.

Fixes: 49866ce7ea8d ("netfs: Add support for caching single monolithic objects such as AFS dirs")
Signed-off-by: Yichong Chen 
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260727130716.1099906-3-dhowells@redhat.com
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: clear PG_private_2 on copy-to-cache append failure

2026-07-28T13:42:31+00:00

netfs_pgpriv2_copy_to_cache() marks the folio with PG_private_2 before
netfs_pgpriv2_copy_folio() appends it to the copy-to-cache rolling
buffer.

If the append fails, the folio is not queued for cache writeback, so
the PG_private_2 state and its reference must be released immediately.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Signed-off-by: Yichong Chen 
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260727130716.1099906-2-dhowells@redhat.com
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: 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)