From 9c573de3283af007ea11c17bde1e4568d9417328 Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Mon, 25 Apr 2016 16:52:38 -0700 Subject: [PATCH] MD: make bio mergeable 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=117051 Reported-and-tested-by: Park Ju Hyung Fixes: 6ac45aeb6bca(block: avoid to merge splitted bio) Cc: stable@vger.kernel.org (v4.3+) Cc: Ming Lei Cc: Neil Brown Reviewed-by: Jens Axboe Signed-off-by: Shaohua Li --- drivers/md/md.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/md/md.c b/drivers/md/md.c index 194580fba7fd..14d3b37944df 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -284,6 +284,8 @@ static blk_qc_t 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(); -- 2.20.1