[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>
diff --git a/net/atm/proc.c b/net/atm/proc.c
index 99fc1fe..3a6be64 100644
--- a/net/atm/proc.c
+++ b/net/atm/proc.c
@@ -22,6 +22,7 @@
 #include <linux/netdevice.h>
 #include <linux/atmclip.h>
 #include <linux/init.h> /* for __init */
+#include <net/net_namespace.h>
 #include <net/atmclip.h>
 #include <asm/uaccess.h>
 #include <asm/atomic.h>
@@ -475,7 +476,7 @@
 		if (e->dirent)
 			remove_proc_entry(e->name, atm_proc_root);
 	}
-	remove_proc_entry("net/atm", NULL);
+	remove_proc_entry("atm", init_net.proc_net);
 }
 
 int __init atm_proc_init(void)
@@ -483,7 +484,7 @@
 	static struct atm_proc_entry *e;
 	int ret;
 
-	atm_proc_root = proc_mkdir("net/atm",NULL);
+	atm_proc_root = proc_mkdir("atm", init_net.proc_net);
 	if (!atm_proc_root)
 		goto err_out;
 	for (e = atm_proc_ents; e->name; e++) {