ipv4: If fib metrics are default, no need to grab ref to FIB info.

The fib metric memory in this case is static in the kernel image,
so we don't need to reference count it since it's never going
to go away on us.

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

net/ipv4/route.c

@@ -1861,8 +1861,10 @@ static void rt_init_metrics(struct rtable *rt, struct fib_info *fi)
 {
 	if (!(rt->fl.flags & FLOWI_FLAG_PRECOW_METRICS)) {
 	no_cow:
-		rt->fi = fi;
-		atomic_inc(&fi->fib_clntref);
+		if (fi->fib_metrics != (u32 *) dst_default_metrics) {
+			rt->fi = fi;
+			atomic_inc(&fi->fib_clntref);
+		}
 		dst_init_metrics(&rt->dst, fi->fib_metrics, true);
 	} else {
 		struct inet_peer *peer;