dm-table: fix checking for rq stackable devices

Due to the semantics of iterate_devices(), the current code allows a
request-based dm table as long as it includes one request-stackable
device. It is supposed to only allow tables where there are no
non-request-stackable devices.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Reviewed-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Author: bmarzins

drivers/md/dm-table.c

@@ -899,17 +899,17 @@ static bool dm_table_supports_dax(struct dm_table *t,
 	return true;
 }
 
-static int device_is_rq_stackable(struct dm_target *ti, struct dm_dev *dev,
-				  sector_t start, sector_t len, void *data)
+static int device_is_not_rq_stackable(struct dm_target *ti, struct dm_dev *dev,
+				      sector_t start, sector_t len, void *data)
 {
 	struct block_device *bdev = dev->bdev;
 	struct request_queue *q = bdev_get_queue(bdev);
 
 	/* request-based cannot stack on partitions! */
 	if (bdev_is_partition(bdev))
-		return false;
+		return true;
 
-	return queue_is_mq(q);
+	return !queue_is_mq(q);
 }
 
 static int dm_table_determine_type(struct dm_table *t)
@@ -1005,7 +1005,7 @@ static int dm_table_determine_type(struct dm_table *t)
 
 	/* Non-request-stackable devices can't be used for request-based dm */
 	if (!ti->type->iterate_devices ||
-	    !ti->type->iterate_devices(ti, device_is_rq_stackable, NULL)) {
+	    ti->type->iterate_devices(ti, device_is_not_rq_stackable, NULL)) {
 		DMERR("table load rejected: including non-request-stackable devices");
 		return -EINVAL;
 	}