btrfs_file_extent_calc_inline_size
size = btrfs_file_extent_calc_inline_size(size);
datasize = btrfs_file_extent_calc_inline_size(cur_size);
drop_args.extent_item_size = btrfs_file_extent_calc_inline_size(data_len);
datasize = btrfs_file_extent_calc_inline_size(name_len);
const size_t inline_size = size - btrfs_file_extent_calc_inline_size(0);
char *data_start = inline_data + btrfs_file_extent_calc_inline_size(0);