ipvs: add sync_persist_mode flag

Add sync_persist_mode flag to reduce sync traffic
by syncing only persistent templates.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Tested-by: Aleksey Chudov <aleksey.chudov@gmail.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

4 files changed, 43 insertions, 0 deletions

diff --git a/Documentation/networking/ipvs-sysctl.txt b/Documentation/networking/ipvs-sysctl.txt
index 9573d0c48c6e..7a3c04729591 100644
--- a/Documentation/networking/ipvs-sysctl.txt
+++ b/Documentation/networking/ipvs-sysctl.txt
@@ -181,6 +181,19 @@ snat_reroute - BOOLEAN
         always be the same as the original route so it is an optimisation
         to disable snat_reroute and avoid the recalculation.
 
+sync_persist_mode - INTEGER
+        default 0
+
+        Controls the synchronisation of connections when using persistence
+
+        0: All types of connections are synchronised
+        1: Attempt to reduce the synchronisation traffic depending on
+        the connection type. For persistent services avoid synchronisation
+        for normal connections, do it only for persistence templates.
+        In such case, for TCP and SCTP it may need enabling sloppy_tcp and
+        sloppy_sctp flags on backup servers. For non-persistent services
+        such optimization is not applied, mode 0 is assumed.
+
 sync_version - INTEGER
         default 1
 
diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index e667df171003..f0d70f066f3d 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -975,6 +975,7 @@ struct netns_ipvs {
         int                     sysctl_snat_reroute;
         int                     sysctl_sync_ver;
         int                     sysctl_sync_ports;
+        int                     sysctl_sync_persist_mode;
         unsigned long           sysctl_sync_qlen_max;
         int                     sysctl_sync_sock_size;
         int                     sysctl_cache_bypass;
@@ -1076,6 +1077,11 @@ static inline int sysctl_sync_ports(struct netns_ipvs *ipvs)
         return ACCESS_ONCE(ipvs->sysctl_sync_ports);
 }
 
+static inline int sysctl_sync_persist_mode(struct netns_ipvs *ipvs)
+{
+        return ipvs->sysctl_sync_persist_mode;
+}
+
 static inline unsigned long sysctl_sync_qlen_max(struct netns_ipvs *ipvs)
 {
         return ipvs->sysctl_sync_qlen_max;
@@ -1139,6 +1145,11 @@ static inline int sysctl_sync_ports(struct netns_ipvs *ipvs)
         return 1;
 }
 
+static inline int sysctl_sync_persist_mode(struct netns_ipvs *ipvs)
+{
+        return 0;
+}
+
 static inline unsigned long sysctl_sync_qlen_max(struct netns_ipvs *ipvs)
 {
         return IPVS_SYNC_QLEN_MAX;
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index da035fc01eb2..c8148e487386 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -1715,6 +1715,12 @@ static struct ctl_table vs_vars[] = {
                 .proc_handler   = &proc_do_sync_ports,
         },
         {
+                .procname       = "sync_persist_mode",
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec,
+        },
+        {
                 .procname       = "sync_qlen_max",
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0644,
@@ -3729,6 +3735,7 @@ static int __net_init ip_vs_control_net_init_sysctl(struct net *net)
         tbl[idx++].data = &ipvs->sysctl_sync_ver;
         ipvs->sysctl_sync_ports = 1;
         tbl[idx++].data = &ipvs->sysctl_sync_ports;
+        tbl[idx++].data = &ipvs->sysctl_sync_persist_mode;
         ipvs->sysctl_sync_qlen_max = nr_free_buffer_pages() / 32;
         tbl[idx++].data = &ipvs->sysctl_sync_qlen_max;
         ipvs->sysctl_sync_sock_size = 0;
diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
index 2fc66394d86d..f4484719f3e6 100644
--- a/net/netfilter/ipvs/ip_vs_sync.c
+++ b/net/netfilter/ipvs/ip_vs_sync.c
@@ -425,6 +425,16 @@ ip_vs_sync_buff_create_v0(struct netns_ipvs *ipvs)
         return sb;
 }
 
+/* Check if connection is controlled by persistence */
+static inline bool in_persistence(struct ip_vs_conn *cp)
+{
+        for (cp = cp->control; cp; cp = cp->control) {
+                if (cp->flags & IP_VS_CONN_F_TEMPLATE)
+                        return true;
+        }
+        return false;
+}
+
 /* Check if conn should be synced.
  * pkts: conn packets, use sysctl_sync_threshold to avoid packet check
  * - (1) sync_refresh_period: reduce sync rate. Additionally, retry
@@ -447,6 +457,8 @@ static int ip_vs_sync_conn_needed(struct netns_ipvs *ipvs,
         /* Check if we sync in current state */
         if (unlikely(cp->flags & IP_VS_CONN_F_TEMPLATE))
                 force = 0;
+        else if (unlikely(sysctl_sync_persist_mode(ipvs) && in_persistence(cp)))
+                return 0;
         else if (likely(cp->protocol == IPPROTO_TCP)) {
                 if (!((1 << cp->state) &
                       ((1 << IP_VS_TCP_S_ESTABLISHED) |