mtd/ubi/block: add error handling support for add_disk()

We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20211103230437.1639990-10-mcgrof@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: mcgrof

drivers/mtd/ubi/block.c

@@ -447,12 +447,18 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	list_add_tail(&dev->list, &ubiblock_devices);
 
 	/* Must be the last step: anyone can call file ops from now on */
-	add_disk(dev->gd);
+	ret = add_disk(dev->gd);
+	if (ret)
+		goto out_destroy_wq;
+
 	dev_info(disk_to_dev(dev->gd), "created from ubi%d:%d(%s)",
 		 dev->ubi_num, dev->vol_id, vi->name);
 	mutex_unlock(&devices_mutex);
 	return 0;
 
+out_destroy_wq:
+	list_del(&dev->list);
+	destroy_workqueue(dev->wq);
 out_remove_minor:
 	idr_remove(&ubiblock_minor_idr, gd->first_minor);
 out_cleanup_disk: