From: Jens Axboe <axboe@kernel.dk>
Date: Wed, 28 Nov 2018 00:07:17 +0000 (-0700)
Subject: blk-mq: fix failure to decrement plug count on single rq removal
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=4711b57317f0ff5ca9fbd5e2df6c73b2c07ddc53;p=openwrt%2Fstaging%2Fblogic.git

blk-mq: fix failure to decrement plug count on single rq removal

If we yank a 'same_queue_rq' request off the plug list, we should
also decrement the cached request count.

Fixes: 5f0ed774ed29 ("block: sum requests in the plug structure")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7b7dff85cf6c..a82830f39933 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1946,8 +1946,10 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 		 */
 		if (list_empty(&plug->mq_list))
 			same_queue_rq = NULL;
-		if (same_queue_rq)
+		if (same_queue_rq) {
 			list_del_init(&same_queue_rq->queuelist);
+			plug->rq_count--;
+		}
 		list_add_tail(&rq->queuelist, &plug->mq_list);
 		plug->rq_count++;