1 files changed, 3 insertions, 3 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 4b4217d9be78..07b706243772 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -577,9 +577,9 @@ static int cfq_allow_merge(request_queue_t *q, struct request *rq,
         pid_t key;
 
         /*
-         * Disallow merge, if bio and rq aren't both sync or async
+         * Disallow merge of a sync bio into an async request.
          */
-        if (!!bio_sync(bio) != !!rq_is_sync(rq))
+        if ((bio_data_dir(bio) == READ || bio_sync(bio)) && !rq_is_sync(rq))
                 return 0;
 
         /*
@@ -592,7 +592,7 @@ static int cfq_allow_merge(request_queue_t *q, struct request *rq,
         if (cfqq == RQ_CFQQ(rq))
                 return 1;
 
-        return 1;
+        return 0;
 }
 
 static inline void