[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/ipv6/anycast.c b/net/ipv6/anycast.c
index b8c533f..0bd66549 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -30,6 +30,7 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 
+#include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/snmp.h>
 
@@ -578,7 +579,7 @@
 
 int __init ac6_proc_init(void)
 {
-	if (!proc_net_fops_create("anycast6", S_IRUGO, &ac6_seq_fops))
+	if (!proc_net_fops_create(&init_net, "anycast6", S_IRUGO, &ac6_seq_fops))
 		return -ENOMEM;
 
 	return 0;
@@ -586,7 +587,7 @@
 
 void ac6_proc_exit(void)
 {
-	proc_net_remove("anycast6");
+	proc_net_remove(&init_net, "anycast6");
 }
 #endif