vop_mmap
.vop_mmap = (void *)vop_einval,
DO_OPS(ap->a_head.a_ops, error, ap, vop_mmap);
DO_OPS(ops, error, &ap, vop_mmap);
vop_mmap(*(vp)->v_ops, vp, fflags, cred)
int (*vop_mmap)(struct vop_mmap_args *);
int vop_mmap(struct vop_ops *ops, struct vnode *vp, int fflags,