dm: convert to blk_alloc_disk/blk_cleanup_disk

Convert the dm driver to use the blk_alloc_disk and blk_cleanup_disk
helpers to simplify gendisk and request_queue allocation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/dm.c

@@ -1801,13 +1801,13 @@ static void cleanup_mapped_device(struct mapped_device *md)
 		md->disk->private_data = NULL;
 		spin_unlock(&_minor_lock);
 		del_gendisk(md->disk);
-		put_disk(md->disk);
 	}
 
-	if (md->queue) {
+	if (md->queue)
 		dm_queue_destroy_keyslot_manager(md->queue);
-		blk_cleanup_queue(md->queue);
-	}
+
+	if (md->disk)
+		blk_cleanup_disk(md->disk);
 
 	cleanup_srcu_struct(&md->io_barrier);
 
@@ -1869,13 +1869,10 @@ static struct mapped_device *alloc_dev(int minor)
 	 * established. If request-based table is loaded: blk-mq will
 	 * override accordingly.
 	 */
-	md->queue = blk_alloc_queue(numa_node_id);
-	if (!md->queue)
-		goto bad;
-
-	md->disk = alloc_disk_node(1, md->numa_node_id);
+	md->disk = blk_alloc_disk(md->numa_node_id);
 	if (!md->disk)
 		goto bad;
+	md->queue = md->disk->queue;
 
 	init_waitqueue_head(&md->wait);
 	INIT_WORK(&md->work, dm_wq_work);
@@ -1888,6 +1885,7 @@ static struct mapped_device *alloc_dev(int minor)
 
 	md->disk->major = _major;
 	md->disk->first_minor = minor;
+	md->disk->minors = 1;
 	md->disk->fops = &dm_blk_dops;
 	md->disk->queue = md->queue;
 	md->disk->private_data = md;