net/ipv4: Add support for specifying metric of connected routes

Add support for IFA_RT_PRIORITY to ipv4 addresses.

If the metric is changed on an existing address then the new route
is inserted before removing the old one. Since the metric is one
of the route keys, the prefix route can not be replaced.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/route.h b/include/net/route.h
index dbb032d..bb53cdb 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -225,6 +225,7 @@ struct rtable *rt_dst_alloc(struct net_device *dev,
 struct in_ifaddr;
 void fib_add_ifaddr(struct in_ifaddr *);
 void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
+void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric);
 
 void rt_add_uncached_list(struct rtable *rt);
 void rt_del_uncached_list(struct rtable *rt);