net: Store ipv4/ipv6 COW'd metrics in inetpeer cache.

Please note that the IPSEC dst entry metrics keep using
the generic metrics COW'ing mechanism using kmalloc/kfree.

This gives the IPSEC routes an opportunity to use metrics
which are unique to their encapsulated paths.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 31 insertions, 2 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 691798c169a5..72609f1c6158 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -97,6 +97,36 @@ static struct rt6_info *rt6_get_route_info(struct net *net,
                                            struct in6_addr *gwaddr, int ifindex);
 #endif
 
+static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)
+{
+        struct rt6_info *rt = (struct rt6_info *) dst;
+        struct inet_peer *peer;
+        u32 *p = NULL;
+
+        if (!rt->rt6i_peer)
+                rt6_bind_peer(rt, 1);
+
+        peer = rt->rt6i_peer;
+        if (peer) {
+                u32 *old_p = __DST_METRICS_PTR(old);
+                unsigned long prev, new;
+
+                p = peer->metrics;
+                if (inet_metrics_new(peer))
+                        memcpy(p, old_p, sizeof(u32) * RTAX_MAX);
+
+                new = (unsigned long) p;
+                prev = cmpxchg(&dst->_metrics, old, new);
+
+                if (prev != old) {
+                        p = __DST_METRICS_PTR(prev);
+                        if (prev & DST_METRICS_READ_ONLY)
+                                p = NULL;
+                }
+        }
+        return p;
+}
+
 static struct dst_ops ip6_dst_ops_template = {
         .family                 =       AF_INET6,
         .protocol               =       cpu_to_be16(ETH_P_IPV6),
@@ -105,7 +135,7 @@ static struct dst_ops ip6_dst_ops_template = {
         .check                  =       ip6_dst_check,
         .default_advmss         =       ip6_default_advmss,
         .default_mtu            =       ip6_default_mtu,
-        .cow_metrics            =       dst_cow_metrics_generic,
+        .cow_metrics            =       ipv6_cow_metrics,
         .destroy                =       ip6_dst_destroy,
         .ifdown                 =       ip6_dst_ifdown,
         .negative_advice        =       ip6_negative_advice,
@@ -198,7 +228,6 @@ static void ip6_dst_destroy(struct dst_entry *dst)
                 rt->rt6i_idev = NULL;
                 in6_dev_put(idev);
         }
-        dst_destroy_metrics_generic(dst);
         if (peer) {
                 rt->rt6i_peer = NULL;
                 inet_putpeer(peer);