VOP_PATHCONF
error = VOP_PATHCONF(vp, SCARG(uap, name), retval);
error = VOP_PATHCONF(nd.ni_vp, name, retval);
error = VOP_PATHCONF(vp, _PC_LINK_MAX, &linkmax);
error = VOP_PATHCONF(vp, _PC_NAME_MAX, &namemax);
error = VOP_PATHCONF(vp, _PC_CHOWN_RESTRICTED, &chownres);
error = VOP_PATHCONF(vp, _PC_NO_TRUNC, ¬runc);
int VOP_PATHCONF(struct vnode *, int, register_t *);