void btrfs_put_block_group(struct btrfs_block_group *cache)
{
	if (refcount_dec_and_test(&cache->refs)) {
		WARN_ON(cache->pinned > 0);
		WARN_ON(cache->reserved > 0);

		/*
		 * A block_group shouldn't be on the discard_list anymore.
		 * Remove the block_group from the discard_list to prevent us
		 * from causing a panic due to NULL pointer dereference.
		 */
		if (WARN_ON(!list_empty(&cache->discard_list)))
			btrfs_discard_cancel_work(&cache->fs_info->discard_ctl,
						  cache);

		/*
		 * If not empty, someone is still holding mutex of
		 * full_stripe_lock, which can only be released by caller.
		 * And it will definitely cause use-after-free when caller
		 * tries to release full stripe lock.
		 *
		 * No better way to resolve, but only to warn.
		 */
		WARN_ON(!RB_EMPTY_ROOT(&cache->full_stripe_locks_root.root));
		kfree(cache->free_space_ctl);
		kfree(cache);
	}
}
void btrfs_put_block_group(struct btrfs_block_group *cache)
{
	if (refcount_dec_and_test(&cache->refs)) {
		WARN_ON(cache->pinned > 0);
		WARN_ON(cache->reserved > 0);

		 
		if (WARN_ON(!list_empty(&cache->discard_list)))
			btrfs_discard_cancel_work(&cache->fs_info->discard_ctl,
						  cache);

		 
		WARN_ON(!RB_EMPTY_ROOT(&cache->full_stripe_locks_root.root));
		kfree(cache->free_space_ctl);
		kfree(cache);
	}
}