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>

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Karl Mehltretter 2026-08-27 14:42:54 +01:00 • committed by Christian Brauner

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commit f18e8774f4

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fs/netfs/direct_write.c

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