VOP_MKDIR
error = VOP_MKDIR(ndp->ni_dvp, &ndp->ni_vp, &ndp->ni_cnd,
error = VOP_MKDIR(dvp, vpp, &cn, &va);
error = VOP_MKDIR(dvp, &vp, cnp, ap->a_vap);
error = VOP_MKDIR(udvp, &uvp, &cn, &va);
if ((error = VOP_MKDIR(udvp, &uvp, cnp, ap->a_vap)) == 0) {
error = VOP_MKDIR(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr);
error = VOP_MKDIR(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &va);
error = VOP_MKDIR(dvp, vpp, cnp, vap);
int VOP_MKDIR(struct vnode *, struct vnode **, struct componentname *,