[NETNS][FRAGS]: Duplicate sysctl tables for new namespaces.

Each namespace has to have own tables to tune their
different parameters, so duplicate the tables and
register them.

All the tables in sub-namespaces are temporarily made
read-only.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 80680e0..15a0b05 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -16,6 +16,7 @@
 struct netns_ipv4 {
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header	*forw_hdr;
+	struct ctl_table_header	*frags_hdr;
 #endif
 	struct ipv4_devconf	*devconf_all;
 	struct ipv4_devconf	*devconf_dflt;