linux-kernel - [PATCH 2/3] block: Check bio can merge before call attempt_plug

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Date:	Wed, 30 Oct 2013 10:41:42 +0800
From:	majianpeng <majianpeng@...il.com>
To:	axboe <axboe@...nel.dk>, NeilBrown <neilb@...e.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	linux-raid <linux-raid@...r.kernel.org>
Subject: [PATCH 2/3] block: Check bio can merge before call attempt_plug_merge.

Signed-off-by: Jianpeng Ma <majianpeng@...il.com>
---
 block/blk-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 0a00e4e..fb970fd 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1492,7 +1492,7 @@ void blk_queue_bio(struct request_queue *q, struct bio *bio)
 	 * Check if we can merge with the plugged list before grabbing
 	 * any locks.
 	 */
-	if (attempt_plug_merge(q, bio, &request_count))
+	if (likely(bio_mergeable(bio)) && attempt_plug_merge(q, bio, &request_count))
 		return;
 
 	spin_lock_irq(q->queue_lock);
-- 
1.8.4