[PATCH] block layer: elv_iosched_show should get elv_list_lock

elv_iosched_show function iterates other elv_list, hence
elv_list_lock should be got.

Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Signed-off-by: Vasily Tarasov <jens.axboe@oracle.com>
diff --git a/block/elevator.c b/block/elevator.c
index d8030a8..8ccd163 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -1085,7 +1085,7 @@
 	struct list_head *entry;
 	int len = 0;
 
-	spin_lock_irq(q->queue_lock);
+	spin_lock_irq(&elv_list_lock);
 	list_for_each(entry, &elv_list) {
 		struct elevator_type *__e;
 
@@ -1095,7 +1095,7 @@
 		else
 			len += sprintf(name+len, "%s ", __e->elevator_name);
 	}
-	spin_unlock_irq(q->queue_lock);
+	spin_unlock_irq(&elv_list_lock);
 
 	len += sprintf(len+name, "\n");
 	return len;