[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/sunrpc/stats.c b/net/sunrpc/stats.c
index 74ba7d4..4d4f373 100644
--- a/net/sunrpc/stats.c
+++ b/net/sunrpc/stats.c
@@ -21,6 +21,7 @@
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/svcsock.h>
 #include <linux/sunrpc/metrics.h>
+#include <net/net_namespace.h>
 
 #define RPCDBG_FACILITY	RPCDBG_MISC
 
@@ -265,7 +266,7 @@
 	dprintk("RPC:       registering /proc/net/rpc\n");
 	if (!proc_net_rpc) {
 		struct proc_dir_entry *ent;
-		ent = proc_mkdir("rpc", proc_net);
+		ent = proc_mkdir("rpc", init_net.proc_net);
 		if (ent) {
 			ent->owner = THIS_MODULE;
 			proc_net_rpc = ent;
@@ -279,7 +280,7 @@
 	dprintk("RPC:       unregistering /proc/net/rpc\n");
 	if (proc_net_rpc) {
 		proc_net_rpc = NULL;
-		remove_proc_entry("net/rpc", NULL);
+		remove_proc_entry("rpc", init_net.proc_net);
 	}
 }