[NET] NETNS: Omit seq_net_private->net without CONFIG_NET_NS.

Without CONFIG_NET_NS, no namespace other than &init_net exists,
no need to store net in seq_net_private.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

fs/proc/proc_net.c

diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 4caa5f7..13cd783 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -44,7 +44,9 @@
 		put_net(net);
 		return -ENOMEM;
 	}
+#ifdef CONFIG_NET_NS
 	p->net = net;
+#endif
 	return 0;
 }
 EXPORT_SYMBOL_GPL(seq_open_net);
@@ -52,12 +54,10 @@
 int seq_release_net(struct inode *ino, struct file *f)
 {
 	struct seq_file *seq;
-	struct seq_net_private *p;
 
 	seq = f->private_data;
-	p = seq->private;
 
-	put_net(p->net);
+	put_net(seq_file_net(seq));
 	seq_release_private(ino, f);
 	return 0;
 }