tcp: Namespace-ify sysctl_tcp_rmem and sysctl_tcp_wmem

Note that when a new netns is created, it inherits its
sysctl_tcp_rmem and sysctl_tcp_wmem from initial netns.

This change is needed so that we can refine TCP rcvbuf autotuning,
to take RTT into consideration.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 0162c57..1eac84b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2409,8 +2409,8 @@ struct proto tcp_prot = {
 	.memory_allocated	= &tcp_memory_allocated,
 	.memory_pressure	= &tcp_memory_pressure,
 	.sysctl_mem		= sysctl_tcp_mem,
-	.sysctl_wmem		= sysctl_tcp_wmem,
-	.sysctl_rmem		= sysctl_tcp_rmem,
+	.sysctl_wmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_wmem),
+	.sysctl_rmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_rmem),
 	.max_header		= MAX_TCP_HEADER,
 	.obj_size		= sizeof(struct tcp_sock),
 	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
@@ -2509,7 +2509,14 @@ static int __net_init tcp_sk_init(struct net *net)
 	net->ipv4.sysctl_tcp_invalid_ratelimit = HZ/2;
 	net->ipv4.sysctl_tcp_pacing_ss_ratio = 200;
 	net->ipv4.sysctl_tcp_pacing_ca_ratio = 120;
-
+	if (net != &init_net) {
+		memcpy(net->ipv4.sysctl_tcp_rmem,
+		       init_net.ipv4.sysctl_tcp_rmem,
+		       sizeof(init_net.ipv4.sysctl_tcp_rmem));
+		memcpy(net->ipv4.sysctl_tcp_wmem,
+		       init_net.ipv4.sysctl_tcp_wmem,
+		       sizeof(init_net.ipv4.sysctl_tcp_wmem));
+	}
 	net->ipv4.sysctl_tcp_fastopen = TFO_CLIENT_ENABLE;
 	spin_lock_init(&net->ipv4.tcp_fastopen_ctx_lock);
 	net->ipv4.sysctl_tcp_fastopen_blackhole_timeout = 60 * 60;