From 8ca9745efe3528feb06ca4e117188038eea2d351 Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@redhat.com>
Date: Thu, 23 Sep 2021 17:11:31 +0800
Subject: [PATCH] dm rq: don't queue request to blk-mq during DM suspend
Git-commit: b4459b11e84092658fa195a2587aff3b9637f0e7
Patch-mainline: v5.15-rc6
References: stable-5.14.14

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@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/md/dm-rq.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 0dbd48cbdff9..231efbe38c21 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -490,6 +490,14 @@ static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 	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);
-- 
2.26.2