linux-kernel - [PATCH v2 2/2] nbd: convert to use blk_mq_get_rq_by

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Date:   Mon, 9 Aug 2021 11:09:27 +0800
From:   Yu Kuai <yukuai3@...wei.com>
To:     <axboe@...nel.dk>, <josef@...icpanda.com>, <bvanassche@....org>,
        <ming.lei@...hat.com>
CC:     <linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <nbd@...er.debian.org>, <yukuai3@...wei.com>, <yi.zhang@...wei.com>
Subject: [PATCH v2 2/2] nbd: convert to use blk_mq_get_rq_by_tag()

blk_mq_tag_to_rq() might return freed request, use
blk_mq_get_rq_by_tag() instead.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 drivers/block/nbd.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index c38317979f74..9e56975a8eee 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -713,11 +713,10 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
 	tag = nbd_handle_to_tag(handle);
 	hwq = blk_mq_unique_tag_to_hwq(tag);
 	if (hwq < nbd->tag_set.nr_hw_queues)
-		req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
-				       blk_mq_unique_tag_to_tag(tag));
-	if (!req || !blk_mq_request_started(req)) {
-		dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
-			tag, req);
+		req = blk_mq_get_rq_by_tag(nbd->tag_set.tags[hwq],
+					   blk_mq_unique_tag_to_tag(tag));
+	if (!req) {
+		dev_err(disk_to_dev(nbd->disk), "Unexpected reply %d\n", tag);
 		return ERR_PTR(-ENOENT);
 	}
 	trace_nbd_header_received(req, handle);
@@ -779,6 +778,8 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
 	}
 out:
 	trace_nbd_payload_received(req, handle);
+	if (req)
+		blk_mq_put_rq_ref(req);
 	mutex_unlock(&cmd->lock);
 	return ret ? ERR_PTR(ret) : cmd;
 }
-- 
2.31.1