RSLOP
if (nbytes <= (n = pagesz - sizeof (*op) - RSLOP)) {
n = -((long)sizeof (*op) + RSLOP);
op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
onb -= sizeof (*op) + RSLOP;
onb += pagesz - sizeof (*op) - RSLOP;
i -= sizeof (*op) + RSLOP;
i += pagesz - sizeof (*op) - RSLOP;
op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);