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netfs: Fix uninitialized return value in netfs_unbuffered_write()

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If preparation of the first subrequest fails,
netfs_unbuffered_write() exits its loop before ret is initialized. The
empty-iterator check can do the same.

For synchronous writes, netfs_unbuffered_write_iter_locked() may then
return an unrelated error instead of wreq->error. This is reachable
through CIFS if cifs_prepare_write() fails to reopen the file or obtain
credits.

Initialize ret to 0 so the caller returns wreq->error if no data was
written, or the number of bytes already written otherwise.

Found with Clang's -Wconditional-uninitialized.

Fixes: a0b4c7a491 ("netfs: Fix unbuffered/DIO writes to dispatch subrequests in strict sequence")
Cc: stable@vger.kernel.org
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260827134304.2075713-2-dhowells@redhat.com
Acked-by: Paulo Alcantara <pc@manguebit.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This commit is contained in:
Karl Mehltretter 2026-08-27 14:42:54 +01:00 committed by Christian Brauner
parent b12e20c6ac
commit f18e8774f4
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1 changed files with 1 additions and 1 deletions
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2
fs/netfs/direct_write.c
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@ -95,7 +95,7 @@ static int netfs_unbuffered_write(struct netfs_io_request *wreq)
{
struct netfs_io_subrequest *subreq = NULL;
struct netfs_io_stream *stream = &wreq->io_streams[0];
int ret;
int ret = 0;
_enter("%llx", wreq->len);