linux-kernel - [PATCH v4 2/5] block: loop: set QUEUE_FLAG

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Message-Id: <1432881338-898-3-git-send-email-ming.lei@canonical.com>
Date:	Fri, 29 May 2015 14:35:35 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	linux-kernel@...r.kernel.org,
	Dave Kleikamp <dave.kleikamp@...cle.com>
Cc:	Jens Axboe <axboe@...nel.dk>, Zach Brown <zab@...bo.net>,
	Christoph Hellwig <hch@...radead.org>,
	Maxim Patlasov <mpatlasov@...allels.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Tejun Heo <tj@...nel.org>, Dave Chinner <david@...morbit.com>,
	Ming Lei <ming.lei@...onical.com>
Subject: [PATCH v4 2/5] block: loop: set QUEUE_FLAG_NOMERGES for request queue of loop

It doesn't make sense to enable merge because the I/O
submitted to backing file is handled page by page.

Signed-off-by: Ming Lei <ming.lei@...onical.com>
---
 drivers/block/loop.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 40580dc..10cc583 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1595,6 +1595,12 @@ static int loop_add(struct loop_device **l, int i)
 	}
 	lo->lo_queue->queuedata = lo;
 
+	/*
+	 * It doesn't make sense to enable merge because the I/O
+	 * submitted to backing file is handled page by page.
+	 */
+	queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, lo->lo_queue);
+
 	INIT_LIST_HEAD(&lo->write_cmd_head);
 	INIT_WORK(&lo->write_work, loop_queue_write_work);
 
-- 
1.9.1

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