ipv4: Prepare for fib6_nh from a nexthop object

Convert more IPv4 code to use fib_nh_common over fib_nh to enable routes
to use a fib6_nh based nexthop. In the end, only code not using a
nexthop object in a fib_info should directly access fib_nh in a fib_info
without checking the famiy and going through fib_nh_common. Those
functions will be marked when it is not directly evident.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 42b1a80..7da8ea78 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -195,8 +195,8 @@ struct fib_result_nl {
 #define FIB_TABLE_HASHSZ 2
 #endif
 
-__be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh,
-				unsigned char scope);
+__be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
+				 unsigned char scope);
 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res);
 
 #define FIB_RES_NHC(res)		((res).nhc)
@@ -455,11 +455,18 @@ static inline void fib_combine_itag(u32 *itag, const struct fib_result *res)
 {
 #ifdef CONFIG_IP_ROUTE_CLASSID
 	struct fib_nh_common *nhc = res->nhc;
-	struct fib_nh *nh = container_of(nhc, struct fib_nh, nh_common);
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 	u32 rtag;
 #endif
-	*itag = nh->nh_tclassid << 16;
+	if (nhc->nhc_family == AF_INET) {
+		struct fib_nh *nh;
+
+		nh = container_of(nhc, struct fib_nh, nh_common);
+		*itag = nh->nh_tclassid << 16;
+	} else {
+		*itag = 0;
+	}
+
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 	rtag = res->tclassid;
 	if (*itag == 0)