From d752c364571743d696c2a54a449ce77550c35ac5 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Mon, 23 Feb 2015 15:02:34 -0300 Subject: [PATCH] ipvs: allow rescheduling of new connections when port reuse is detected Currently, when TCP/SCTP port reusing happens, IPVS will find the old entry and use it for the new one, behaving like a forced persistence. But if you consider a cluster with a heavy load of small connections, such reuse will happen often and may lead to a not optimal load balancing and might prevent a new node from getting a fair load. This patch introduces a new sysctl, conn_reuse_mode, that allows controlling how to proceed when port reuse is detected. The default value will allow rescheduling of new connections only if the old entry was in TIME_WAIT state for TCP or CLOSED for SCTP. Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: Julian Anastasov Signed-off-by: Simon Horman --- Documentation/networking/ipvs-sysctl.txt | 21 +++++++++++++++ include/net/ip_vs.h | 11 ++++++++ net/netfilter/ipvs/ip_vs_core.c | 33 +++++++++++++++++++++--- net/netfilter/ipvs/ip_vs_ctl.c | 8 ++++++ net/netfilter/ipvs/ip_vs_sync.c | 21 +++++++++++++-- 5 files changed, 88 insertions(+), 6 deletions(-) diff --git a/Documentation/networking/ipvs-sysctl.txt b/Documentation/networking/ipvs-sysctl.txt index 7a3c047295914c..3ba709531adba9 100644 --- a/Documentation/networking/ipvs-sysctl.txt +++ b/Documentation/networking/ipvs-sysctl.txt @@ -22,6 +22,27 @@ backup_only - BOOLEAN If set, disable the director function while the server is in backup mode to avoid packet loops for DR/TUN methods. +conn_reuse_mode - INTEGER + 1 - default + + Controls how ipvs will deal with connections that are detected + port reuse. It is a bitmap, with the values being: + + 0: disable any special handling on port reuse. The new + connection will be delivered to the same real server that was + servicing the previous connection. This will effectively + disable expire_nodest_conn. + + bit 1: enable rescheduling of new connections when it is safe. + That is, whenever expire_nodest_conn and for TCP sockets, when + the connection is in TIME_WAIT state (which is only possible if + you use NAT mode). + + bit 2: it is bit 1 plus, for TCP connections, when connections + are in FIN_WAIT state, as this is the last state seen by load + balancer in Direct Routing mode. This bit helps on adding new + real servers to a very busy cluster. + conntrack - BOOLEAN 0 - disabled (default) not 0 - enabled diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h index a627fe690c19c7..20fd23398537c3 100644 --- a/include/net/ip_vs.h +++ b/include/net/ip_vs.h @@ -941,6 +941,7 @@ struct netns_ipvs { int sysctl_nat_icmp_send; int sysctl_pmtu_disc; int sysctl_backup_only; + int sysctl_conn_reuse_mode; /* ip_vs_lblc */ int sysctl_lblc_expiration; @@ -1059,6 +1060,11 @@ static inline int sysctl_backup_only(struct netns_ipvs *ipvs) ipvs->sysctl_backup_only; } +static inline int sysctl_conn_reuse_mode(struct netns_ipvs *ipvs) +{ + return ipvs->sysctl_conn_reuse_mode; +} + #else static inline int sysctl_sync_threshold(struct netns_ipvs *ipvs) @@ -1126,6 +1132,11 @@ static inline int sysctl_backup_only(struct netns_ipvs *ipvs) return 0; } +static inline int sysctl_conn_reuse_mode(struct netns_ipvs *ipvs) +{ + return 1; +} + #endif /* IPVS core functions diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c index c9470c86308f5f..6103ab933c5b2b 100644 --- a/net/netfilter/ipvs/ip_vs_core.c +++ b/net/netfilter/ipvs/ip_vs_core.c @@ -1042,6 +1042,26 @@ static inline bool is_new_conn(const struct sk_buff *skb, } } +static inline bool is_new_conn_expected(const struct ip_vs_conn *cp, + int conn_reuse_mode) +{ + /* Controlled (FTP DATA or persistence)? */ + if (cp->control) + return false; + + switch (cp->protocol) { + case IPPROTO_TCP: + return (cp->state == IP_VS_TCP_S_TIME_WAIT) || + ((conn_reuse_mode & 2) && + (cp->state == IP_VS_TCP_S_FIN_WAIT) && + (cp->flags & IP_VS_CONN_F_NOOUTPUT)); + case IPPROTO_SCTP: + return cp->state == IP_VS_SCTP_S_CLOSED; + default: + return false; + } +} + /* Handle response packets: rewrite addresses and send away... */ static unsigned int @@ -1580,6 +1600,7 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, int af) struct ip_vs_conn *cp; int ret, pkts; struct netns_ipvs *ipvs; + int conn_reuse_mode; /* Already marked as IPVS request or reply? */ if (skb->ipvs_property) @@ -1648,10 +1669,14 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, int af) */ cp = pp->conn_in_get(af, skb, &iph, 0); - if (unlikely(sysctl_expire_nodest_conn(ipvs)) && cp && cp->dest && - unlikely(!atomic_read(&cp->dest->weight)) && !iph.fragoffs && - is_new_conn(skb, &iph)) { - ip_vs_conn_expire_now(cp); + conn_reuse_mode = sysctl_conn_reuse_mode(ipvs); + if (conn_reuse_mode && !iph.fragoffs && + is_new_conn(skb, &iph) && cp && + ((unlikely(sysctl_expire_nodest_conn(ipvs)) && cp->dest && + unlikely(!atomic_read(&cp->dest->weight))) || + unlikely(is_new_conn_expected(cp, conn_reuse_mode)))) { + if (!atomic_read(&cp->n_control)) + ip_vs_conn_expire_now(cp); __ip_vs_conn_put(cp); cp = NULL; } diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index 6fd60059faf01a..76cc9ffd87fa80 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -1823,6 +1823,12 @@ static struct ctl_table vs_vars[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "conn_reuse_mode", + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, #ifdef CONFIG_IP_VS_DEBUG { .procname = "debug_level", @@ -3790,6 +3796,8 @@ static int __net_init ip_vs_control_net_init_sysctl(struct net *net) ipvs->sysctl_pmtu_disc = 1; tbl[idx++].data = &ipvs->sysctl_pmtu_disc; tbl[idx++].data = &ipvs->sysctl_backup_only; + ipvs->sysctl_conn_reuse_mode = 1; + tbl[idx++].data = &ipvs->sysctl_conn_reuse_mode; ipvs->sysctl_hdr = register_net_sysctl(net, "net/ipv4/vs", tbl); diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c index c47ffd7a0a709c..f96229cdb6e184 100644 --- a/net/netfilter/ipvs/ip_vs_sync.c +++ b/net/netfilter/ipvs/ip_vs_sync.c @@ -845,10 +845,27 @@ static void ip_vs_proc_conn(struct net *net, struct ip_vs_conn_param *param, struct ip_vs_conn *cp; struct netns_ipvs *ipvs = net_ipvs(net); - if (!(flags & IP_VS_CONN_F_TEMPLATE)) + if (!(flags & IP_VS_CONN_F_TEMPLATE)) { cp = ip_vs_conn_in_get(param); - else + if (cp && ((cp->dport != dport) || + !ip_vs_addr_equal(cp->daf, &cp->daddr, daddr))) { + if (!(flags & IP_VS_CONN_F_INACTIVE)) { + ip_vs_conn_expire_now(cp); + __ip_vs_conn_put(cp); + cp = NULL; + } else { + /* This is the expiration message for the + * connection that was already replaced, so we + * just ignore it. + */ + __ip_vs_conn_put(cp); + kfree(param->pe_data); + return; + } + } + } else { cp = ip_vs_ct_in_get(param); + } if (cp) { /* Free pe_data */