net: ib_net pointer should depends on CONFIG_NET_NS

We can shrink size of "struct inet_bind_bucket" by 50%, using
read_pnet() and write_pnet()

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 5cc182f..cb31fbf 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -77,13 +77,20 @@
  * ports are created in O(1) time?  I thought so. ;-)	-DaveM
  */
 struct inet_bind_bucket {
+#ifdef CONFIG_NET_NS
 	struct net		*ib_net;
+#endif
 	unsigned short		port;
 	signed short		fastreuse;
 	struct hlist_node	node;
 	struct hlist_head	owners;
 };
 
+static inline struct net *ib_net(struct inet_bind_bucket *ib)
+{
+	return read_pnet(&ib->ib_net);
+}
+
 #define inet_bind_bucket_for_each(tb, node, head) \
 	hlist_for_each_entry(tb, node, head, node)