_PC_DEALLOC_PRESENT
error = VOP_PATHCONF(be_lun->vn, _PC_DEALLOC_PRESENT, &pconf);
error = VOP_PATHCONF(nd.ni_vp, _PC_DEALLOC_PRESENT, &v);
case _PC_DEALLOC_PRESENT:
candelete = fpathconf(fd, _PC_DEALLOC_PRESENT) == 1;