SBD_DEVS_UNREFERENCED
if (SBD_DEVS_RELEASED(sbp) == SBD_DEVS_UNREFERENCED(sbp)) {
devset = HD2MACHHD(hp)->sh_devset & SBD_DEVS_UNREFERENCED(sbp);
if (SBD_DEVS_UNREFERENCED(sbp) == 0) {