B_COLD
if (ISSET(bp->b_flags, B_COLD)) {
CLR(bp->b_flags, B_COLD);
if (ISSET(bp->b_flags, B_COLD)) {
CLR(bp->b_flags, B_COLD);
if (ISSET(bp->b_flags, B_COLD)) {
SET(bp->b_flags, B_COLD);
if (ISSET(bp->b_flags, B_WARM | B_COLD)) {
CLR(bp->b_flags, B_COLD);
CLR(bp->b_flags, B_COLD);