There's already some stuff on the struct net, that should better
be folded into netns_core structure. I'm making the per-proto inuse 
counter be per-net also, which is also a candidate for this, so 
introduce this structure and populate it a bit.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>