blk-mq: put driver tag if dispatch budget can't be got

We have to put the driver tag if dispatch budget can't be got, otherwise it might cause IO deadlock, especially in case that size of tags is very small. Fixes: de14829(blk-mq: introduce .get_budget and .put_budget in blk_mq_ops) Signed-off-by: Ming Lei <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
kyagi · Nov 11, 2017 · 0c6af1c · 0c6af1c
1 parent f00c4d8
commit 0c6af1c
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/block/blk-mq.c b/block/blk-mq.c
@@ -1080,8 +1080,10 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
 			}
 		}
 
-		if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
+		if (!got_budget && !blk_mq_get_dispatch_budget(hctx)) {
+			blk_mq_put_driver_tag(rq);
 			break;
+		}
 
 		list_del_init(&rq->queuelist);