block: Fix blk_start_queueing() to not kick a stopped queue

blk_start_queueing() should act like the generic queue unplugging
and kicking and ignore a stopped queue. Such a queue may not be
run until after a call to blk_start_queue().

Signed-off-by: Elias Oltmanns <eo@nebensachen.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/blk-core.c

@@ -890,9 +890,11 @@ EXPORT_SYMBOL(blk_get_request);
  */
 void blk_start_queueing(struct request_queue *q)
 {
-	if (!blk_queue_plugged(q))
+	if (!blk_queue_plugged(q)) {
+		if (unlikely(blk_queue_stopped(q)))
+			return;
 		q->request_fn(q);
-	else
+	} else
 		__generic_unplug_device(q);
 }
 EXPORT_SYMBOL(blk_start_queueing);