[PATCH 01/15] ipvs: Add simple weighted failover scheduler

[Simon Horman <horms@xxxxxxxxxxxx>]

From: Kenny Mathis <kmathis@xxxxxxxxxxxxxx>

Add simple weighted IPVS failover support to the Linux kernel. All
other scheduling modules implement some form of load balancing, while
this offers a simple failover solution. Connections are directed to
the appropriate server based solely on highest weight value and server
availability. Tested functionality with keepalived.

Signed-off-by: Kenny Mathis <kmathis@xxxxxxxxxxxxxx>
Acked-by: Julian Anastasov <ja@xxxxxx>
Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
---
 net/netfilter/ipvs/Kconfig    | 10 ++++++
 net/netfilter/ipvs/Makefile   |  1 +
 net/netfilter/ipvs/ip_vs_fo.c | 79 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+)
 create mode 100644 net/netfilter/ipvs/ip_vs_fo.c

diff --git a/net/netfilter/ipvs/Kconfig b/net/netfilter/ipvs/Kconfig
index 0c3b167..3b6929d 100644
--- a/net/netfilter/ipvs/Kconfig
+++ b/net/netfilter/ipvs/Kconfig
@@ -152,6 +152,16 @@ config     IP_VS_WLC
          If you want to compile it in kernel, say Y. To compile it as a
          module, choose M here. If unsure, say N.
 
+config  IP_VS_FO
+               tristate "weighted failover scheduling"
+       ---help---
+         The weighted failover scheduling algorithm directs network
+         connections to the server with the highest weight that is
+         currently available.
+
+         If you want to compile it in kernel, say Y. To compile it as a
+         module, choose M here. If unsure, say N.
+
 config IP_VS_LBLC
        tristate "locality-based least-connection scheduling"
        ---help---
diff --git a/net/netfilter/ipvs/Makefile b/net/netfilter/ipvs/Makefile
index 34ee602..38b2723 100644
--- a/net/netfilter/ipvs/Makefile
+++ b/net/netfilter/ipvs/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_IP_VS_RR) += ip_vs_rr.o
 obj-$(CONFIG_IP_VS_WRR) += ip_vs_wrr.o
 obj-$(CONFIG_IP_VS_LC) += ip_vs_lc.o
 obj-$(CONFIG_IP_VS_WLC) += ip_vs_wlc.o
+obj-$(CONFIG_IP_VS_FO) += ip_vs_fo.o
 obj-$(CONFIG_IP_VS_LBLC) += ip_vs_lblc.o
 obj-$(CONFIG_IP_VS_LBLCR) += ip_vs_lblcr.o
 obj-$(CONFIG_IP_VS_DH) += ip_vs_dh.o
diff --git a/net/netfilter/ipvs/ip_vs_fo.c b/net/netfilter/ipvs/ip_vs_fo.c
new file mode 100644
index 0000000..6a2647d
--- /dev/null
+++ b/net/netfilter/ipvs/ip_vs_fo.c
@@ -0,0 +1,79 @@
+/*
+ * IPVS:        Weighted Fail Over module
+ *
+ * Authors:     Kenny Mathis <kmathis@xxxxxxxxxxxxxx>
+ *
+ *              This program is free software; you can redistribute it and/or
+ *              modify it under the terms of the GNU General Public License
+ *              as published by the Free Software Foundation; either version
+ *              2 of the License, or (at your option) any later version.
+ *
+ * Changes:
+ *     Kenny Mathis            :     added initial functionality based on 
weight
+ *
+ */
+
+#define KMSG_COMPONENT "IPVS"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include <net/ip_vs.h>
+
+/* Weighted Fail Over Module */
+static struct ip_vs_dest *
+ip_vs_fo_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
+                 struct ip_vs_iphdr *iph)
+{
+       struct ip_vs_dest *dest, *hweight = NULL;
+       int hw = 0; /* Track highest weight */
+
+       IP_VS_DBG(6, "ip_vs_fo_schedule(): Scheduling...\n");
+
+       /* Basic failover functionality
+        * Find virtual server with highest weight and send it traffic
+        */
+       list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
+               if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
+                   atomic_read(&dest->weight) > hw) {
+                       hweight = dest;
+                       hw = atomic_read(&dest->weight);
+               }
+       }
+
+       if (hweight) {
+               IP_VS_DBG_BUF(6, "FO: server %s:%u activeconns %d weight %d\n",
+                             IP_VS_DBG_ADDR(svc->af, &hweight->addr),
+                             ntohs(hweight->port),
+                             atomic_read(&hweight->activeconns),
+                             atomic_read(&hweight->weight));
+               return hweight;
+       }
+
+       ip_vs_scheduler_err(svc, "no destination available");
+       return NULL;
+}
+
+static struct ip_vs_scheduler ip_vs_fo_scheduler = {
+       .name =                 "fo",
+       .refcnt =               ATOMIC_INIT(0),
+       .module =               THIS_MODULE,
+       .n_list =               LIST_HEAD_INIT(ip_vs_fo_scheduler.n_list),
+       .schedule =             ip_vs_fo_schedule,
+};
+
+static int __init ip_vs_fo_init(void)
+{
+       return register_ip_vs_scheduler(&ip_vs_fo_scheduler);
+}
+
+static void __exit ip_vs_fo_cleanup(void)
+{
+       unregister_ip_vs_scheduler(&ip_vs_fo_scheduler);
+       synchronize_rcu();
+}
+
+module_init(ip_vs_fo_init);
+module_exit(ip_vs_fo_cleanup);
+MODULE_LICENSE("GPL");
-- 
2.0.1

--
To unsubscribe from this list: send the line "unsubscribe lvs-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html