dm: make flush bios explicitly sync
authorJan Kara <jack@suse.cz>
Wed, 31 May 2017 07:44:32 +0000 (09:44 +0200)
committerMike Snitzer <snitzer@redhat.com>
Wed, 31 May 2017 14:50:23 +0000 (10:50 -0400)
commitff0361b34ac63ef80c785c32d62e0e9d89a2cf89
treedf6bce75c164f09c052d464bfbf4d2ba7f44797e
parent8c1e2162f27b319da913683143c0c6c09b083ebb
dm: make flush bios explicitly sync

Commit b685d3d65ac7 ("block: treat REQ_FUA and REQ_PREFLUSH as
synchronous") removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...}
definitions.  generic_make_request_checks() however strips REQ_FUA and
REQ_PREFLUSH flags from a bio when the storage doesn't report volatile
write cache and thus write effectively becomes asynchronous which can
lead to performance regressions.

Fix the problem by making sure all bios which are synchronous are
properly marked with REQ_SYNC.

Fixes: b685d3d65ac7 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous")
Cc: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
drivers/md/dm-bufio.c
drivers/md/dm-integrity.c
drivers/md/dm-raid1.c
drivers/md/dm-snap-persistent.c
drivers/md/dm.c