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>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index dd57f48..b1e5d3a 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1861,8 +1861,10 @@
 {
 	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;