net/netfilter/ipvs/ip_vs_fo.c

   1 /*
   2  * IPVS:        Weighted Fail Over module
   3  *
   4  * Authors:     Kenny Mathis <kmathis@chokepoint.net>
   5  *
   6  *              This program is free software; you can redistribute it and/or
   7  *              modify it under the terms of the GNU General Public License
   8  *              as published by the Free Software Foundation; either version
   9  *              2 of the License, or (at your option) any later version.
  10  *
  11  * Changes:
  12  *     Kenny Mathis            :     added initial functionality based on weight
  13  *
  14  */
  15
  16 #define KMSG_COMPONENT "IPVS"
  17 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  18
  19 #include <linux/module.h>
  20 #include <linux/kernel.h>
  21
  22 #include <net/ip_vs.h>
  23
  24 /* Weighted Fail Over Module */
  25 static struct ip_vs_dest *
  26 ip_vs_fo_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
  27                   struct ip_vs_iphdr *iph)
  28 {
  29         struct ip_vs_dest *dest, *hweight = NULL;
  30         int hw = 0; /* Track highest weight */
  31
  32         IP_VS_DBG(6, "ip_vs_fo_schedule(): Scheduling...\n");
  33
  34         /* Basic failover functionality
  35          * Find virtual server with highest weight and send it traffic
  36          */
  37         list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
  38                 if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
  39                     atomic_read(&dest->weight) > hw) {
  40                         hweight = dest;
  41                         hw = atomic_read(&dest->weight);
  42                 }
  43         }
  44
  45         if (hweight) {
  46                 IP_VS_DBG_BUF(6, "FO: server %s:%u activeconns %d weight %d\n",
  47                               IP_VS_DBG_ADDR(hweight->af, &hweight->addr),
  48                               ntohs(hweight->port),
  49                               atomic_read(&hweight->activeconns),
  50                               atomic_read(&hweight->weight));
  51                 return hweight;
  52         }
  53
  54         ip_vs_scheduler_err(svc, "no destination available");
  55         return NULL;
  56 }
  57
  58 static struct ip_vs_scheduler ip_vs_fo_scheduler = {
  59         .name =                 "fo",
  60         .refcnt =               ATOMIC_INIT(0),
  61         .module =               THIS_MODULE,
  62         .n_list =               LIST_HEAD_INIT(ip_vs_fo_scheduler.n_list),
  63         .schedule =             ip_vs_fo_schedule,
  64 };
  65
  66 static int __init ip_vs_fo_init(void)
  67 {
  68         return register_ip_vs_scheduler(&ip_vs_fo_scheduler);
  69 }
  70
  71 static void __exit ip_vs_fo_cleanup(void)
  72 {
  73         unregister_ip_vs_scheduler(&ip_vs_fo_scheduler);
  74         synchronize_rcu();
  75 }
  76
  77 module_init(ip_vs_fo_init);
  78 module_exit(ip_vs_fo_cleanup);
  79 MODULE_LICENSE("GPL");