fs: assert that open_mutex isn't held over holder ops

With recent block level changes we should never be in a situation where
we hold disk->open_mutex when calling into these helpers. So assert that
in the code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231017184823.1383356-6-hch@lst.deReviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/super.c

@@ -1433,6 +1433,7 @@ static struct super_block *bdev_super_lock_shared(struct block_device *bdev)
 
 	lockdep_assert_held(&bdev->bd_holder_lock);
 	lockdep_assert_not_held(&sb->s_umount);
+	lockdep_assert_not_held(&bdev->bd_disk->open_mutex);
 
 	/* Make sure sb doesn't go away from under us */
 	spin_lock(&sb_lock);