fs_readdir
extern int fs_readdir(struct fs_fhandle *, char *, long *,
erc = fs_readdir(&p_dir_info->fd_dir_fh,
rv = fs_readdir(&tsp->ts_fh, pn.tn_path,
rv = fs_readdir(&tsp->ts_fh, pn.tn_path,
static int fs_readdir(void *, struct l9p_request *);
backend->readdir = fs_readdir;