zap_maxcd
uint32_t zap_maxcd(zap_t *zap);
ASSERT3U(cd, <, zap_maxcd(zn->zn_zap));
ASSERT(cd < zap_maxcd(zap));
ASSERT((zc->zc_hash & zap_maxcd(zc->zc_zap)) == 0);
ASSERT(zc->zc_cd < zap_maxcd(zc->zc_zap));
if (zc->zc_cd >= zap_maxcd(zc->zc_zap)) /* corrupt serialized */