linux-kernel - [PATCH v2 4/7] blk-mq: check bio_mergeable() early before merging

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Message-Id: <1445354037-27000-5-git-send-email-ming.lei@canonical.com>
Date:	Tue, 20 Oct 2015 23:13:54 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org
Cc:	Ming Lin <ming.l@....samsung.com>,
	Kent Overstreet <kent.overstreet@...il.com>,
	Christoph Hellwig <hch@...radead.org>,
	Jeff Moyer <jmoyer@...hat.com>,
	Ming Lei <ming.lei@...onical.com>
Subject: [PATCH v2 4/7] blk-mq: check bio_mergeable() early before merging

It isn't necessary to try to merge the bio which is marked
as NOMERGE.

Reviewed-by: Jeff Moyer <jmoyer@...hat.com>
Signed-off-by: Ming Lei <ming.lei@...onical.com>
---
 block/blk-mq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1796b31..edbc877 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1140,7 +1140,7 @@ static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
 					 struct blk_mq_ctx *ctx,
 					 struct request *rq, struct bio *bio)
 {
-	if (!hctx_allow_merges(hctx)) {
+	if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
 		blk_mq_bio_to_request(rq, bio);
 		spin_lock(&ctx->lock);
 insert_rq:
-- 
1.9.1

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