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-rw-r--r--block/cfq-iosched.c21
1 files changed, 8 insertions, 13 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9fc5eafa6c0..4b4217d9be7 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -577,25 +577,20 @@ static int cfq_allow_merge(request_queue_t *q, struct request *rq,
pid_t key;
/*
- * If bio is async or a write, always allow merge
+ * Disallow merge, if bio and rq aren't both sync or async
*/
- if (!bio_sync(bio) || rw == WRITE)
- return 1;
-
- /*
- * bio is sync. if request is not, disallow.
- */
- if (!rq_is_sync(rq))
+ if (!!bio_sync(bio) != !!rq_is_sync(rq))
return 0;
/*
- * Ok, both bio and request are sync. Allow merge if they are
- * from the same queue.
+ * Lookup the cfqq that this bio will be queued with. Allow
+ * merge only if rq is queued there.
*/
- key = cfq_queue_pid(current, rw, 1);
+ key = cfq_queue_pid(current, rw, bio_sync(bio));
cfqq = cfq_find_cfq_hash(cfqd, key, current->ioprio);
- if (cfqq != RQ_CFQQ(rq))
- return 0;
+
+ if (cfqq == RQ_CFQQ(rq))
+ return 1;
return 1;
}