RDONLY
(un->un_oflags & FWRITE) ? RDWR : RDONLY;
(un->un_oflags & FWRITE) ? RDWR : RDONLY;
un->un_read_only = RDONLY;
un->un_read_only = RDONLY;
if (un->un_mspl->wp || un->un_read_only & RDONLY) {