{
 }
 
+static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
+                                         unsigned long old)
+{
+       return NULL;
+}
+
 static struct dst_ops ipv4_dst_blackhole_ops = {
        .family                 =       AF_INET,
        .protocol               =       cpu_to_be16(ETH_P_IP),
        .default_mtu            =       ipv4_blackhole_default_mtu,
        .default_advmss         =       ipv4_default_advmss,
        .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
+       .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
 };
 
 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
 
 {
 }
 
+static u32 *ip6_rt_blackhole_cow_metrics(struct dst_entry *dst,
+                                        unsigned long old)
+{
+       return NULL;
+}
+
 static struct dst_ops ip6_dst_blackhole_ops = {
        .family                 =       AF_INET6,
        .protocol               =       cpu_to_be16(ETH_P_IPV6),
        .default_mtu            =       ip6_blackhole_default_mtu,
        .default_advmss         =       ip6_default_advmss,
        .update_pmtu            =       ip6_rt_blackhole_update_pmtu,
+       .cow_metrics            =       ip6_rt_blackhole_cow_metrics,
 };
 
 static const u32 ip6_template_metrics[RTAX_MAX] = {