dm: don't schedule delayed run of the queue if nothing to do

In request-based DM's dm_request_fn(), if blk_peek_request() returns
NULL just return.  Avoids unnecessary blk_delay_queue().

Reported-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 7924c00..6f85428 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1963,7 +1963,7 @@ static void dm_request_fn(struct request_queue *q)
        while (!blk_queue_stopped(q)) {
                rq = blk_peek_request(q);
                if (!rq)
-                       goto delay_and_out;
+                       goto out;
 
                /* always use block 0 to find the target for flushes for now */
                pos = 0;