linux-kernel - [PATCH 5.14 020/151] dm rq: dont queue request to blk-mq during DM suspend

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Message-Id: <20211018132341.334019450@linuxfoundation.org>
Date:   Mon, 18 Oct 2021 15:23:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ming Lei <ming.lei@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>
Subject: [PATCH 5.14 020/151] dm rq: dont queue request to blk-mq during DM suspend

From: Ming Lei <ming.lei@...hat.com>

commit b4459b11e84092658fa195a2587aff3b9637f0e7 upstream.

DM uses blk-mq's quiesce/unquiesce to stop/start device mapper queue.

But blk-mq's unquiesce may come from outside events, such as elevator
switch, updating nr_requests or others, and request may come during
suspend, so simply ask for blk-mq to requeue it.

Fixes one kernel panic issue when running updating nr_requests and
dm-mpath suspend/resume stress test.

Cc: stable@...r.kernel.org
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/md/dm-rq.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -490,6 +490,14 @@ static blk_status_t dm_mq_queue_rq(struc
 	struct mapped_device *md = tio->md;
 	struct dm_target *ti = md->immutable_target;
 
+	/*
+	 * blk-mq's unquiesce may come from outside events, such as
+	 * elevator switch, updating nr_requests or others, and request may
+	 * come during suspend, so simply ask for blk-mq to requeue it.
+	 */
+	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)))
+		return BLK_STS_RESOURCE;
+
 	if (unlikely(!ti)) {
 		int srcu_idx;
 		struct dm_table *map = dm_get_live_table(md, &srcu_idx);