net: Abstract away all dst_entry metrics accesses.

Use helper functions to hide all direct accesses, especially writes,
to dst_entry metrics values.

This will allow us to:

1) More easily change how the metrics are stored.

2) Implement COW for metrics.

In particular this will help us put metrics into the inetpeer
cache if that is what we end up doing.  We can make the _metrics
member a pointer instead of an array, initially have it point
at the read-only metrics in the FIB, and then on the first set
grab an inetpeer entry and point the _metrics member there.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

2 files changed, 40 insertions, 31 deletions

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index e18f84130203..2342545a5ee9 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1259,7 +1259,8 @@ static void ndisc_router_discovery(struct sk_buff *skb)
         if (ra_msg->icmph.icmp6_hop_limit) {
                 in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit;
                 if (rt)
-                        rt->dst.metrics[RTAX_HOPLIMIT-1] = ra_msg->icmph.icmp6_hop_limit;
+                        dst_metric_set(&rt->dst, RTAX_HOPLIMIT,
+                                       ra_msg->icmph.icmp6_hop_limit);
         }
 
 skip_defrtr:
@@ -1377,7 +1378,7 @@ skip_linkparms:
                         in6_dev->cnf.mtu6 = mtu;
 
                         if (rt)
-                                rt->dst.metrics[RTAX_MTU-1] = mtu;
+                                dst_metric_set(&rt->dst, RTAX_MTU, mtu);
 
                         rt6_mtu_change(skb->dev, mtu);
                 }
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 026caef0326c..4aed0812b512 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -129,7 +129,6 @@ static struct rt6_info ip6_null_entry_template = {
                 .__use          = 1,
                 .obsolete       = -1,
                 .error          = -ENETUNREACH,
-                .metrics        = { [RTAX_HOPLIMIT - 1] = 255, },
                 .input          = ip6_pkt_discard,
                 .output         = ip6_pkt_discard_out,
         },
@@ -150,7 +149,6 @@ static struct rt6_info ip6_prohibit_entry_template = {
                 .__use          = 1,
                 .obsolete       = -1,
                 .error          = -EACCES,
-                .metrics        = { [RTAX_HOPLIMIT - 1] = 255, },
                 .input          = ip6_pkt_prohibit,
                 .output         = ip6_pkt_prohibit_out,
         },
@@ -166,7 +164,6 @@ static struct rt6_info ip6_blk_hole_entry_template = {
                 .__use          = 1,
                 .obsolete       = -1,
                 .error          = -EINVAL,
-                .metrics        = { [RTAX_HOPLIMIT - 1] = 255, },
                 .input          = dst_discard,
                 .output         = dst_discard,
         },
@@ -844,7 +841,7 @@ int ip6_dst_blackhole(struct sock *sk, struct dst_entry **dstp, struct flowi *fl
                 new->input = dst_discard;
                 new->output = dst_discard;
 
-                memcpy(new->metrics, ort->dst.metrics, RTAX_MAX*sizeof(u32));
+                dst_copy_metrics(new, &ort->dst);
                 new->dev = ort->dst.dev;
                 if (new->dev)
                         dev_hold(new->dev);
@@ -928,10 +925,12 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, u32 mtu)
         if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) {
                 rt6->rt6i_flags |= RTF_MODIFIED;
                 if (mtu < IPV6_MIN_MTU) {
+                        u32 features = dst_metric(dst, RTAX_FEATURES);
                         mtu = IPV6_MIN_MTU;
-                        dst->metrics[RTAX_FEATURES-1] |= RTAX_FEATURE_ALLFRAG;
+                        features |= RTAX_FEATURE_ALLFRAG;
+                        dst_metric_set(dst, RTAX_FEATURES, features);
                 }
-                dst->metrics[RTAX_MTU-1] = mtu;
+                dst_metric_set(dst, RTAX_MTU, mtu);
                 call_netevent_notifiers(NETEVENT_PMTU_UPDATE, dst);
         }
 }
@@ -989,9 +988,9 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
         rt->rt6i_idev     = idev;
         rt->rt6i_nexthop  = neigh;
         atomic_set(&rt->dst.__refcnt, 1);
-        rt->dst.metrics[RTAX_HOPLIMIT-1] = 255;
-        rt->dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(rt->rt6i_dev);
-        rt->dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(net, dst_mtu(&rt->dst));
+        dst_metric_set(&rt->dst, RTAX_HOPLIMIT, 255);
+        dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(rt->rt6i_dev));
+        dst_metric_set(&rt->dst, RTAX_ADVMSS, ipv6_advmss(net, dst_mtu(&rt->dst)));
         rt->dst.output  = ip6_output;
 
 #if 0   /* there's no chance to use these for ndisc */
@@ -1305,17 +1304,17 @@ install_route:
                                         goto out;
                                 }
 
-                                rt->dst.metrics[type - 1] = nla_get_u32(nla);
+                                dst_metric_set(&rt->dst, type, nla_get_u32(nla));
                         }
                 }
         }
 
         if (dst_metric(&rt->dst, RTAX_HOPLIMIT) == 0)
-                rt->dst.metrics[RTAX_HOPLIMIT-1] = -1;
+                dst_metric_set(&rt->dst, RTAX_HOPLIMIT, -1);
         if (!dst_mtu(&rt->dst))
-                rt->dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(dev);
+                dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(dev));
         if (!dst_metric(&rt->dst, RTAX_ADVMSS))
-                rt->dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(net, dst_mtu(&rt->dst));
+                dst_metric_set(&rt->dst, RTAX_ADVMSS, ipv6_advmss(net, dst_mtu(&rt->dst)));
         rt->dst.dev = dev;
         rt->rt6i_idev = idev;
         rt->rt6i_table = table;
@@ -1541,9 +1540,9 @@ void rt6_redirect(struct in6_addr *dest, struct in6_addr *src,
         ipv6_addr_copy(&nrt->rt6i_gateway, (struct in6_addr*)neigh->primary_key);
         nrt->rt6i_nexthop = neigh_clone(neigh);
         /* Reset pmtu, it may be better */
-        nrt->dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(neigh->dev);
-        nrt->dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(dev_net(neigh->dev),
-                                                        dst_mtu(&nrt->dst));
+        dst_metric_set(&nrt->dst, RTAX_MTU, ipv6_get_mtu(neigh->dev));
+        dst_metric_set(&nrt->dst, RTAX_ADVMSS, ipv6_advmss(dev_net(neigh->dev),
+                                                           dst_mtu(&nrt->dst)));
 
         if (ip6_ins_rt(nrt))
                 goto out;
@@ -1602,9 +1601,12 @@ static void rt6_do_pmtu_disc(struct in6_addr *daddr, struct in6_addr *saddr,
            would return automatically.
          */
         if (rt->rt6i_flags & RTF_CACHE) {
-                rt->dst.metrics[RTAX_MTU-1] = pmtu;
-                if (allfrag)
-                        rt->dst.metrics[RTAX_FEATURES-1] |= RTAX_FEATURE_ALLFRAG;
+                dst_metric_set(&rt->dst, RTAX_MTU, pmtu);
+                if (allfrag) {
+                        u32 features = dst_metric(&rt->dst, RTAX_FEATURES);
+                        features |= RTAX_FEATURE_ALLFRAG;
+                        dst_metric_set(&rt->dst, RTAX_FEATURES, features);
+                }
                 dst_set_expires(&rt->dst, net->ipv6.sysctl.ip6_rt_mtu_expires);
                 rt->rt6i_flags |= RTF_MODIFIED|RTF_EXPIRES;
                 goto out;
@@ -1621,9 +1623,12 @@ static void rt6_do_pmtu_disc(struct in6_addr *daddr, struct in6_addr *saddr,
                 nrt = rt6_alloc_clone(rt, daddr);
 
         if (nrt) {
-                nrt->dst.metrics[RTAX_MTU-1] = pmtu;
-                if (allfrag)
-                        nrt->dst.metrics[RTAX_FEATURES-1] |= RTAX_FEATURE_ALLFRAG;
+                dst_metric_set(&nrt->dst, RTAX_MTU, pmtu);
+                if (allfrag) {
+                        u32 features = dst_metric(&nrt->dst, RTAX_FEATURES);
+                        features |= RTAX_FEATURE_ALLFRAG;
+                        dst_metric_set(&nrt->dst, RTAX_FEATURES, features);
+                }
 
                 /* According to RFC 1981, detecting PMTU increase shouldn't be
                  * happened within 5 mins, the recommended timer is 10 mins.
@@ -1674,7 +1679,7 @@ static struct rt6_info * ip6_rt_copy(struct rt6_info *ort)
                 rt->dst.input = ort->dst.input;
                 rt->dst.output = ort->dst.output;
 
-                memcpy(rt->dst.metrics, ort->dst.metrics, RTAX_MAX*sizeof(u32));
+                dst_copy_metrics(&rt->dst, &ort->dst);
                 rt->dst.error = ort->dst.error;
                 rt->dst.dev = ort->dst.dev;
                 if (rt->dst.dev)
@@ -1966,9 +1971,9 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
         rt->dst.output = ip6_output;
         rt->rt6i_dev = net->loopback_dev;
         rt->rt6i_idev = idev;
-        rt->dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(rt->rt6i_dev);
-        rt->dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(net, dst_mtu(&rt->dst));
-        rt->dst.metrics[RTAX_HOPLIMIT-1] = -1;
+        dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(rt->rt6i_dev));
+        dst_metric_set(&rt->dst, RTAX_ADVMSS, ipv6_advmss(net, dst_mtu(&rt->dst)));
+        dst_metric_set(&rt->dst, RTAX_HOPLIMIT, -1);
         rt->dst.obsolete = -1;
 
         rt->rt6i_flags = RTF_UP | RTF_NONEXTHOP;
@@ -2068,8 +2073,8 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg)
             (dst_mtu(&rt->dst) >= arg->mtu ||
              (dst_mtu(&rt->dst) < arg->mtu &&
               dst_mtu(&rt->dst) == idev->cnf.mtu6))) {
-                rt->dst.metrics[RTAX_MTU-1] = arg->mtu;
-                rt->dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(net, arg->mtu);
+                dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu);
+                dst_metric_set(&rt->dst, RTAX_ADVMSS, ipv6_advmss(net, arg->mtu));
         }
         return 0;
 }
@@ -2295,7 +2300,7 @@ static int rt6_fill_node(struct net *net,
                         NLA_PUT(skb, RTA_PREFSRC, 16, &saddr_buf);
         }
 
-        if (rtnetlink_put_metrics(skb, rt->dst.metrics) < 0)
+        if (rtnetlink_put_metrics(skb, dst_metrics_ptr(&rt->dst)) < 0)
                 goto nla_put_failure;
 
         if (rt->dst.neighbour)
@@ -2686,6 +2691,7 @@ static int __net_init ip6_route_net_init(struct net *net)
         net->ipv6.ip6_null_entry->dst.path =
                 (struct dst_entry *)net->ipv6.ip6_null_entry;
         net->ipv6.ip6_null_entry->dst.ops = &net->ipv6.ip6_dst_ops;
+        dst_metric_set(&net->ipv6.ip6_null_entry->dst, RTAX_HOPLIMIT, 255);
 
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
         net->ipv6.ip6_prohibit_entry = kmemdup(&ip6_prohibit_entry_template,
@@ -2696,6 +2702,7 @@ static int __net_init ip6_route_net_init(struct net *net)
         net->ipv6.ip6_prohibit_entry->dst.path =
                 (struct dst_entry *)net->ipv6.ip6_prohibit_entry;
         net->ipv6.ip6_prohibit_entry->dst.ops = &net->ipv6.ip6_dst_ops;
+        dst_metric_set(&net->ipv6.ip6_prohibit_entry->dst, RTAX_HOPLIMIT, 255);
 
         net->ipv6.ip6_blk_hole_entry = kmemdup(&ip6_blk_hole_entry_template,
                                                sizeof(*net->ipv6.ip6_blk_hole_entry),
@@ -2705,6 +2712,7 @@ static int __net_init ip6_route_net_init(struct net *net)
         net->ipv6.ip6_blk_hole_entry->dst.path =
                 (struct dst_entry *)net->ipv6.ip6_blk_hole_entry;
         net->ipv6.ip6_blk_hole_entry->dst.ops = &net->ipv6.ip6_dst_ops;
+        dst_metric_set(&net->ipv6.ip6_blk_hole_entry->dst, RTAX_HOPLIMIT, 255);
 #endif
 
         net->ipv6.sysctl.flush_delay = 0;