Use WARN() in block/

Use WARN() instead of a printk+WARN_ON() pair; this way the message
becomes part of the warning section for better reporting/collection.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

block/as-iosched.c

@@ -837,8 +837,7 @@ static void as_completed_request(struct request_queue *q, struct request *rq)
 	WARN_ON(!list_empty(&rq->queuelist));
 
 	if (RQ_STATE(rq) != AS_RQ_REMOVED) {
-		printk("rq->state %d\n", RQ_STATE(rq));
-		WARN_ON(1);
+		WARN(1, "rq->state %d\n", RQ_STATE(rq));
 		goto out;
 	}