Commit 92b914e2 authored by Shin'ichiro Kawasaki's avatar Shin'ichiro Kawasaki Committed by Mike Snitzer
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dm: fix bio length of empty flush 



The commit 92986f6b ("dm: use bio_clone_fast in alloc_io/alloc_tio")
removed bio_clone_fast() call from alloc_tio() when ci->io->tio is
available. In this case, ci->bio is not copied to ci->io->tio.clone.
This is fine since init_clone_info() sets same values to ci->bio and
ci->io->tio.clone.

However, when incoming bios have REQ_PREFLUSH flag, __send_empty_flush()
prepares a zero length bio on stack and set it to ci->bio. At this time,
ci->io->tio.clone still keeps non-zero length. When alloc_tio() chooses
this ci->io->tio.clone as the bio to map, it is passed to targets as
non-empty flush bio. It causes bio length check failure in dm-zoned and
unexpected operation such as dm_accept_partial_bio() call.

To avoid the non-empty flush bio, set zero length to ci->io->tio.clone
in __send_empty_flush().

Fixes: 92986f6b ("dm: use bio_clone_fast in alloc_io/alloc_tio")
Signed-off-by: default avatarShin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent 7dd06a25

drivers/md/dm.c

+1 −0
Original line number Diff line number Diff line
@@ -1391,6 +1391,7 @@ static void __send_empty_flush(struct clone_info *ci) 


	ci->bio = &flush_bio;

	ci->sector_count = 0;

	ci->io->tio.clone.bi_iter.bi_size = 0;



	while ((ti = dm_table_get_target(ci->map, target_nr++)))

		__send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);