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

Greg Kroah-Hartman
2021-10-18T13:49:53Z

From: Ming Lei <ming.lei@redhat.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@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>
---
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);