block: assert the locking state in delete_partition

Add a lockdep assert instead of the outdated locking comment.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Chaitanya Kulkarni <ckulkarnilinux@gmail.com>
Link: https://lore.kernel.org/r/20210722075402.983367-3-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/partitions/core.c

@@ -281,12 +281,10 @@ struct device_type part_type = {
 	.uevent		= part_uevent,
 };
 
-/*
- * Must be called either with open_mutex held, before a disk can be opened or
- * after all disk users are gone.
- */
 static void delete_partition(struct block_device *part)
 {
+	lockdep_assert_held(&part->bd_disk->open_mutex);
+
 	fsync_bdev(part);
 	__invalidate_device(part, true);