From ff0361b34ac63ef80c785c32d62e0e9d89a2cf89 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 31 May 2017 09:44:32 +0200 Subject: 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 Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/md/dm.c') diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 6ef9500226c0..37ccd73c79ec 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1657,7 +1657,7 @@ static struct mapped_device *alloc_dev(int minor) bio_init(&md->flush_bio, NULL, 0); md->flush_bio.bi_bdev = md->bdev; - md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH; + md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC; dm_stats_init(&md->stats); -- cgit v1.2.3