rem: err = EINVAL;
add: err = FS_EINVAL;
context: sys_wstat(bool kernel, int fd, const char *path, struct my_stat *st, long mask,        bool eatlink){    int         err;    vnode       *vn;    op_wstat    *op;    err = get_file_fd(kernel, fd, path, eatlink, &vn);    if (err)        goto error1;    op = vn->ns->fs->ops.wstat;    if (!op) {        err = EINVAL;        goto error2;    }    err = (*op)(vn->ns->data, vn->data, st, mask);    if (err)        goto error2;    dec_vnode(vn, FALSE);    return 0;error2:    dec_vnode(vn, FALSE);error1:    return err;}