VRING_DESC_F_NEXT
if ((vp->flags & VRING_DESC_F_NEXT) == 0)
if ((vdir->flags & VRING_DESC_F_NEXT) == 0)
if ((vp.vd_flags & VRING_DESC_F_NEXT) == 0) {
if ((vdir.vd_flags & VRING_DESC_F_NEXT) != 0) {
if ((vdir.vd_flags & VRING_DESC_F_NEXT) == 0) {