Commit 4c6a2934 authored by Shaohua Li's avatar Shaohua Li Committed by Sasha Levin

MD: make bio mergeable

[ Upstream commit 9c573de3 ]

blk_queue_split marks bio unmergeable, which makes sense for normal bio.
But if dispatching the bio to underlayer disk, the blk_queue_split
checks are invalid, hence it's possible the bio becomes mergeable.

In the reported bug, this bug causes trim against raid0 performance slash
https://bugzilla.kernel.org/show_bug.cgi?id=117051Reported-and-tested-by: default avatarPark Ju Hyung <qkrwngud825@gmail.com>
Fixes: 6ac45aeb(block: avoid to merge splitted bio)
Cc: stable@vger.kernel.org (v4.3+)
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Neil Brown <neilb@suse.de>
Reviewed-by: default avatarJens Axboe <axboe@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
parent 44c1efb3
......@@ -282,6 +282,8 @@ static void md_make_request(struct request_queue *q, struct bio *bio)
* go away inside make_request
*/
sectors = bio_sectors(bio);
/* bio could be mergeable after passing to underlayer */
bio->bi_rw &= ~REQ_NOMERGE;
mddev->pers->make_request(mddev, bio);
cpu = part_stat_lock();
......
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