btrfs_drop_and_free_fs_root
btrfs_drop_and_free_fs_root(fs_info, gang[0]);
btrfs_drop_and_free_fs_root(fs_info, gang[i]);
btrfs_drop_and_free_fs_root(fs_info, fs_info->data_reloc_root);
void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
btrfs_drop_and_free_fs_root(fs_info, root);