[PATCH 14/20] blkio: Do not allow request merging across cfq groups

[Vivek Goyal]

o Do not allow request merging across cfq groups.

Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
 block/cfq-iosched.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 6936519..87b1799 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1381,6 +1381,9 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
 	struct cfq_io_context *cic;
 	struct cfq_queue *cfqq;
 
+	/* Deny merge if bio and rq don't belong to same cfq group */
+	if (cfqq_to_cfqg(RQ_CFQQ(rq)) != cfq_get_cfqg(cfqd, 0))
+		return false;
 	/*
 	 * Disallow merge of a sync bio into an async request.
 	 */
-- 
1.6.2.5

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