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From: Shaohua Li <shli@fb.com>
To: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-raid@vger.kernel.org
Cc: qkrwngud825@gmail.com, Kernel-team@fb.com,
	"v4.3+" <stable@vger.kernel.org>,
	Ming Lei <ming.lei@canonical.com>, Jens Axboe <axboe@fb.com>,
	Neil Brown <neilb@suse.de>
Subject: [PATCH] MD: make bio mergeable
Date: Mon, 25 Apr 2016 16:52:38 -0700	[thread overview]
Message-ID: <384a0e0c7d6f2700aadbcbdef003cece88fa7dd7.1461626533.git.shli@fb.com> (raw)

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-by: Park Ju Hyung <qkrwngud825@gmail.com>
Fixes: 6ac45aeb6bca(block: avoid to merge splitted bio)
Cc: stable@vger.kernel.org (v4.3+)
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Shaohua Li <shli@fb.com>
---
 drivers/md/md.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 194580f..14d3b37 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();
-- 
2.8.0.rc2

WARNING: multiple messages have this Message-ID (diff)
From: Shaohua Li <shli@fb.com>
To: <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-raid@vger.kernel.org>
Cc: <qkrwngud825@gmail.com>, <Kernel-team@fb.com>,
	"v4.3+" <stable@vger.kernel.org>,
	Ming Lei <ming.lei@canonical.com>, Jens Axboe <axboe@fb.com>,
	Neil Brown <neilb@suse.de>
Subject: [PATCH] MD: make bio mergeable
Date: Mon, 25 Apr 2016 16:52:38 -0700	[thread overview]
Message-ID: <384a0e0c7d6f2700aadbcbdef003cece88fa7dd7.1461626533.git.shli@fb.com> (raw)

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-by: Park Ju Hyung <qkrwngud825@gmail.com>
Fixes: 6ac45aeb6bca(block: avoid to merge splitted bio)
Cc: stable@vger.kernel.org (v4.3+)
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Shaohua Li <shli@fb.com>
---
 drivers/md/md.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 194580f..14d3b37 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();
-- 
2.8.0.rc2

             reply	other threads:[~2016-04-25 23:52 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-25 23:52 Shaohua Li [this message]
2016-04-25 23:52 ` [PATCH] MD: make bio mergeable Shaohua Li
2016-04-26  0:59 ` Jens Axboe
2016-04-26  1:15   ` Jens Axboe
2016-04-26  9:56 ` Ming Lei
2016-04-26  9:56   ` Ming Lei
2016-04-26 14:21   ` Jens Axboe
2016-04-26 14:21     ` Jens Axboe
2016-04-26 15:17     ` Ming Lei
2016-04-26 15:17       ` Ming Lei
2016-04-28 20:00 ` Holger Kiehl
2016-04-28 21:19   ` Shaohua Li
2016-04-28 21:19     ` Shaohua Li
2016-04-29  9:23     ` Holger Kiehl

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