MTF_WRT
if ((sc->sc_flags & MTF_WRT) != 0) {
sc->sc_flags &= ~MTF_WRT;
sc->sc_flags |= MTF_WRT | MTF_IO;
if (sc->sc_flags & MTF_WRT) {
sc->sc_flags &= ~MTF_WRT;
sc->sc_flags |= MTF_WRT | MTF_IO;