cfq: choose a new next_req when a request is dispatched

This patch addresses http://bugzilla.kernel.org/show_bug.cgi?id=13401, a
regression introduced in 2.6.30.

From the bug report:

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index a34686f091db..0e3814b662af 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1110,6 +1110,7 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
 
         cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
 
+        cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
         cfq_remove_request(rq);
         cfqq->dispatched++;
         elv_dispatch_sort(q, rq);