blk-mq: Put driver tag in blk_mq_dispatch_rq_list() when no budget

mainline inclusion
from mainline-5.7-rc2
commit 5fe56de7
category: bugfix
bugzilla: 42779
CVE: NA

---------------------------

If in blk_mq_dispatch_rq_list() we find no budget, then we break of the
dispatch loop, but the request may keep the driver tag, evaulated
in 'nxt' in the previous loop iteration.

Fix by putting the driver tag for that request.
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Conflict: block/blk-mq.c
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NYufen Yu <yuyufen@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

block/blk-mq.c

@@ -1154,8 +1154,10 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
 		rq = list_first_entry(list, struct request, queuelist);
 
 		hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
-		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;
+		}
 
 		if (!blk_mq_get_driver_tag(rq)) {
 			/*