fnvlist_lookup_int32
type = (dmu_objset_type_t)fnvlist_lookup_int32(innvl, "type");
fd = fnvlist_lookup_int32(innvl, "fd");
instance = fnvlist_lookup_int32(nvlist, DEV_INSTANCE);
int32_t fnvlist_lookup_int32(nvlist_t *nvl, const char *name);