[NET]: Make /proc/net per network namespace

This patch makes /proc/net per network namespace.  It modifies the global
variables proc_net and proc_net_stat to be per network namespace.
The proc_net file helpers are modified to take a network namespace argument,
and all of their callers are fixed to pass &init_net for that argument.
This ensures that all of the /proc/net files are only visible and
usable in the initial network namespace until the code behind them
has been updated to be handle multiple network namespaces.

Making /proc/net per namespace is necessary as at least some files
in /proc/net depend upon the set of network devices which is per
network namespace, and even more files in /proc/net have contents
that are relevant to a single network namespace.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/appletalk/atalk_proc.c

@@ -11,6 +11,7 @@
 #include <linux/init.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
+#include <net/net_namespace.h>
 #include <net/sock.h>
 #include <linux/atalk.h>
 
@@ -271,7 +272,7 @@ int __init atalk_proc_init(void)
 	struct proc_dir_entry *p;
 	int rc = -ENOMEM;
 
-	atalk_proc_dir = proc_mkdir("atalk", proc_net);
+	atalk_proc_dir = proc_mkdir("atalk", init_net.proc_net);
 	if (!atalk_proc_dir)
 		goto out;
 	atalk_proc_dir->owner = THIS_MODULE;
@@ -306,7 +307,7 @@ out_socket:
 out_route:
 	remove_proc_entry("interface", atalk_proc_dir);
 out_interface:
-	remove_proc_entry("atalk", proc_net);
+	remove_proc_entry("atalk", init_net.proc_net);
 	goto out;
 }
 
@@ -316,5 +317,5 @@ void __exit atalk_proc_exit(void)
 	remove_proc_entry("route", atalk_proc_dir);
 	remove_proc_entry("socket", atalk_proc_dir);
 	remove_proc_entry("arp", atalk_proc_dir);
-	remove_proc_entry("atalk", proc_net);
+	remove_proc_entry("atalk", init_net.proc_net);
 }