Commit 3654e611 authored by Julian Anastasov's avatar Julian Anastasov Committed by Simon Horman
Browse files

ipvs: add pmtu_disc option to disable IP DF for TUN packets 



	Disabling PMTU discovery can increase the output packet
rate but some users have enough resources and prefer to fragment
than to drop traffic. By default, we copy the DF bit but if
pmtu_disc is disabled we do not send FRAG_NEEDED messages anymore.

Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarSimon Horman <horms@verge.net.au>
parent f2edb9f7

include/net/ip_vs.h

+11 −0
Original line number Diff line number Diff line
@@ -888,6 +888,7 @@ struct netns_ipvs { 
	unsigned int		sysctl_sync_refresh_period;

	int			sysctl_sync_retries;

	int			sysctl_nat_icmp_send;

	int			sysctl_pmtu_disc;



	/* ip_vs_lblc */

	int			sysctl_lblc_expiration;
@@ -974,6 +975,11 @@ static inline int sysctl_sync_sock_size(struct netns_ipvs *ipvs) 
	return ipvs->sysctl_sync_sock_size;

}



static inline int sysctl_pmtu_disc(struct netns_ipvs *ipvs)

{

	return ipvs->sysctl_pmtu_disc;

}



#else



static inline int sysctl_sync_threshold(struct netns_ipvs *ipvs)
@@ -1016,6 +1022,11 @@ static inline int sysctl_sync_sock_size(struct netns_ipvs *ipvs) 
	return 0;

}



static inline int sysctl_pmtu_disc(struct netns_ipvs *ipvs)

{

	return 1;

}



#endif



/*

net/netfilter/ipvs/ip_vs_ctl.c

+8 −0
Original line number Diff line number Diff line
@@ -1801,6 +1801,12 @@ static struct ctl_table vs_vars[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dointvec,

	},

	{

		.procname	= "pmtu_disc",

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= proc_dointvec,

	},

#ifdef CONFIG_IP_VS_DEBUG

	{

		.procname	= "debug_level",
@@ -3726,6 +3732,8 @@ static int __net_init ip_vs_control_net_init_sysctl(struct net *net) 
	ipvs->sysctl_sync_retries = clamp_t(int, DEFAULT_SYNC_RETRIES, 0, 3);

	tbl[idx++].data = &ipvs->sysctl_sync_retries;

	tbl[idx++].data = &ipvs->sysctl_nat_icmp_send;

	ipvs->sysctl_pmtu_disc = 1;

	tbl[idx++].data = &ipvs->sysctl_pmtu_disc;





	ipvs->sysctl_hdr = register_net_sysctl(net, "net/ipv4/vs", tbl);

net/netfilter/ipvs/ip_vs_xmit.c

+3 −3
Original line number Diff line number Diff line
@@ -795,6 +795,7 @@ int 
ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,

		  struct ip_vs_protocol *pp)

{

	struct netns_ipvs *ipvs = net_ipvs(skb_net(skb));

	struct rtable *rt;			/* Route to the other host */

	__be32 saddr;				/* Source for tunnel */

	struct net_device *tdev;		/* Device to other host */
@@ -830,10 +831,9 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, 
		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);



	/* Copy DF, reset fragment offset and MF */

	df = old_iph->frag_off & htons(IP_DF);

	df = sysctl_pmtu_disc(ipvs) ? old_iph->frag_off & htons(IP_DF) : 0;



	if ((old_iph->frag_off & htons(IP_DF) &&

	    mtu < ntohs(old_iph->tot_len) && !skb_is_gso(skb))) {

	if (df && mtu < ntohs(old_iph->tot_len) && !skb_is_gso(skb)) {

		icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));

		IP_VS_DBG_RL("%s(): frag needed\n", __func__);

		goto tx_error_put;

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