KFILTER_BYFILTER
IOCTL_STRUCT_CONV_TO(KFILTER_BYFILTER, kfilter_mapping);
case KFILTER_BYFILTER: /* convert filter -> name */
RL(ioctl(kq, KFILTER_BYFILTER, &km));
ATF_REQUIRE_EQ(ioctl(kq, KFILTER_BYFILTER, &km), -1);