static int get_default_subvolid(int fd, u64 *default_id)

{

	struct btrfs_ioctl_search_args args;

	struct btrfs_ioctl_search_key *sk = &args.key;

	struct btrfs_ioctl_search_header *sh;

	u64 found = 0;

	int ret;

	memset(&args, 0, sizeof(args));

	/*

	 * search for a dir item with a name 'default' in the tree of

	 * tree roots, it should point us to a default root

	 */

	sk->tree_id = 1;

	/* don't worry about ancient format and request only one item */

	sk->nr_items = 1;

	sk->max_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;

	sk->min_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;

	sk->max_type = BTRFS_DIR_ITEM_KEY;

	sk->min_type = BTRFS_DIR_ITEM_KEY;

	sk->max_offset = (u64)-1;

	sk->max_transid = (u64)-1;

	ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);

	if (ret < 0)

		return ret;

	/* the ioctl returns the number of items it found in nr_items */

	if (sk->nr_items == 0)

		goto out;

	sh = (struct btrfs_ioctl_search_header *)args.buf;

	if (sh->type == BTRFS_DIR_ITEM_KEY) {

		struct btrfs_dir_item *di;

		int name_len;

		char *name;

		di = (struct btrfs_dir_item *)(sh + 1);

		name_len = btrfs_stack_dir_name_len(di);

		name = (char *)(di + 1);

		if (!strncmp("default", name, name_len))

			found = btrfs_disk_key_objectid(&di->location);

	}

out:

	*default_id = found;

	return 0;

}

	u64 default_id;

	if (get_default) {

		ret = get_default_subvolid(fd, &default_id);

		if (ret) {

			fprintf(stderr, "ERROR: can't perform the search - %s\n",

				strerror(errno));

			return ret;

		}

		if (default_id == 0) {

			fprintf(stderr, "ERROR: 'default' dir item not found\n");

			return ret;

		}

		/* no need to resolve roots if FS_TREE is default */

		if (default_id == BTRFS_FS_TREE_OBJECTID) {

			printf("ID 5 (FS_TREE)\n");

			return ret;

		}

	}

		if (get_default && entry->root_id != default_id) {

			n = rb_prev(n);

			continue;

		}

BTRFS_SETGET_STACK_FUNCS(stack_dir_name_len, struct btrfs_dir_item, name_len, 16);