[PATCH 4.8 64/85] dm table: an all_blk_mq table must be loaded for a blk-mq DM device

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>

commit 301fc3f5efb98633115bd887655b19f42c6dfaa8 upstream.

When dm_table_set_type() is used by a target to establish a DM table's
type (e.g. DM_TYPE_MQ_REQUEST_BASED in the case of DM multipath) the
DM core must go on to verify that the devices in the table are
compatible with the established type.

Fixes: e83068a5 ("dm mpath: add optional "queue_mode" feature")
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/md/dm-table.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -981,6 +981,11 @@ verify_rq_based:
 		t->all_blk_mq = true;
 	}
 
+	if (t->type == DM_TYPE_MQ_REQUEST_BASED && !t->all_blk_mq) {
+		DMERR("table load rejected: all devices are not blk-mq request-stackable");
+		return -EINVAL;
+	}
+
 	return 0;
 }