HDR_LEN
rv += msync((caddr_t)DB_HDR(hdp), HDR_LEN, MS_SYNC);
(void) munmap((caddr_t)DB_HDR(hdp), HDR_LEN);
if (rv == -1 || sz < HDR_LEN) {
cp = mmap(0, HDR_LEN, flg, MAP_SHARED, fd, 0);
sz = HDR_LEN;
sz = ((HDR_LEN / page_sz) + 1) * page_sz;