MS_IOCWAIT
if (!(msd->msd_flags & MS_IOCWAIT) ||
msd->msd_flags &= ~MS_IOCWAIT;
msd->msd_flags |= MS_IOCWAIT; /* indicate that we're waiting for */
while (msd->msd_flags & MS_IOCWAIT) {
msd->msd_flags |= MS_IOCTOSS|MS_IOCWAIT;