VFSTOISOFS
imp = VFSTOISOFS(mp);
isomp = VFSTOISOFS(mp);
struct iso_mnt *imp = VFSTOISOFS(mp);
isomp = VFSTOISOFS(mp);
VFSTOISOFS(mp)->iso_ftype == ISO_FTYPE_RRIP,
imp = VFSTOISOFS(mp);