| /* |
| * IPVS: Destination Hashing scheduling module |
| * |
| * Authors: Wensong Zhang <wensong@gnuchina.org> |
| * |
| * Inspired by the consistent hashing scheduler patch from |
| * Thomas Proell <proellt@gmx.de> |
| * |
| * 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: |
| * |
| */ |
| |
| /* |
| * The dh algorithm is to select server by the hash key of destination IP |
| * address. The pseudo code is as follows: |
| * |
| * n <- servernode[dest_ip]; |
| * if (n is dead) OR |
| * (n is overloaded) OR (n.weight <= 0) then |
| * return NULL; |
| * |
| * return n; |
| * |
| * Notes that servernode is a 256-bucket hash table that maps the hash |
| * index derived from packet destination IP address to the current server |
| * array. If the dh scheduler is used in cache cluster, it is good to |
| * combine it with cache_bypass feature. When the statically assigned |
| * server is dead or overloaded, the load balancer can bypass the cache |
| * server and send requests to the original server directly. |
| * |
| */ |
| |
| #define KMSG_COMPONENT "IPVS" |
| #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
| |
| #include <linux/ip.h> |
| #include <linux/slab.h> |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/skbuff.h> |
| |
| #include <net/ip_vs.h> |
| |
| |
| /* |
| * IPVS DH bucket |
| */ |
| struct ip_vs_dh_bucket { |
| struct ip_vs_dest __rcu *dest; /* real server (cache) */ |
| }; |
| |
| /* |
| * for IPVS DH entry hash table |
| */ |
| #ifndef CONFIG_IP_VS_DH_TAB_BITS |
| #define CONFIG_IP_VS_DH_TAB_BITS 8 |
| #endif |
| #define IP_VS_DH_TAB_BITS CONFIG_IP_VS_DH_TAB_BITS |
| #define IP_VS_DH_TAB_SIZE (1 << IP_VS_DH_TAB_BITS) |
| #define IP_VS_DH_TAB_MASK (IP_VS_DH_TAB_SIZE - 1) |
| |
| struct ip_vs_dh_state { |
| struct ip_vs_dh_bucket buckets[IP_VS_DH_TAB_SIZE]; |
| struct rcu_head rcu_head; |
| }; |
| |
| /* |
| * Returns hash value for IPVS DH entry |
| */ |
| static inline unsigned int ip_vs_dh_hashkey(int af, const union nf_inet_addr *addr) |
| { |
| __be32 addr_fold = addr->ip; |
| |
| #ifdef CONFIG_IP_VS_IPV6 |
| if (af == AF_INET6) |
| addr_fold = addr->ip6[0]^addr->ip6[1]^ |
| addr->ip6[2]^addr->ip6[3]; |
| #endif |
| return (ntohl(addr_fold)*2654435761UL) & IP_VS_DH_TAB_MASK; |
| } |
| |
| |
| /* |
| * Get ip_vs_dest associated with supplied parameters. |
| */ |
| static inline struct ip_vs_dest * |
| ip_vs_dh_get(int af, struct ip_vs_dh_state *s, const union nf_inet_addr *addr) |
| { |
| return rcu_dereference(s->buckets[ip_vs_dh_hashkey(af, addr)].dest); |
| } |
| |
| |
| /* |
| * Assign all the hash buckets of the specified table with the service. |
| */ |
| static int |
| ip_vs_dh_reassign(struct ip_vs_dh_state *s, struct ip_vs_service *svc) |
| { |
| int i; |
| struct ip_vs_dh_bucket *b; |
| struct list_head *p; |
| struct ip_vs_dest *dest; |
| bool empty; |
| |
| b = &s->buckets[0]; |
| p = &svc->destinations; |
| empty = list_empty(p); |
| for (i=0; i<IP_VS_DH_TAB_SIZE; i++) { |
| dest = rcu_dereference_protected(b->dest, 1); |
| if (dest) |
| ip_vs_dest_put(dest); |
| if (empty) |
| RCU_INIT_POINTER(b->dest, NULL); |
| else { |
| if (p == &svc->destinations) |
| p = p->next; |
| |
| dest = list_entry(p, struct ip_vs_dest, n_list); |
| ip_vs_dest_hold(dest); |
| RCU_INIT_POINTER(b->dest, dest); |
| |
| p = p->next; |
| } |
| b++; |
| } |
| return 0; |
| } |
| |
| |
| /* |
| * Flush all the hash buckets of the specified table. |
| */ |
| static void ip_vs_dh_flush(struct ip_vs_dh_state *s) |
| { |
| int i; |
| struct ip_vs_dh_bucket *b; |
| struct ip_vs_dest *dest; |
| |
| b = &s->buckets[0]; |
| for (i=0; i<IP_VS_DH_TAB_SIZE; i++) { |
| dest = rcu_dereference_protected(b->dest, 1); |
| if (dest) { |
| ip_vs_dest_put(dest); |
| RCU_INIT_POINTER(b->dest, NULL); |
| } |
| b++; |
| } |
| } |
| |
| |
| static int ip_vs_dh_init_svc(struct ip_vs_service *svc) |
| { |
| struct ip_vs_dh_state *s; |
| |
| /* allocate the DH table for this service */ |
| s = kzalloc(sizeof(struct ip_vs_dh_state), GFP_KERNEL); |
| if (s == NULL) |
| return -ENOMEM; |
| |
| svc->sched_data = s; |
| IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) allocated for " |
| "current service\n", |
| sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE); |
| |
| /* assign the hash buckets with current dests */ |
| ip_vs_dh_reassign(s, svc); |
| |
| return 0; |
| } |
| |
| |
| static void ip_vs_dh_done_svc(struct ip_vs_service *svc) |
| { |
| struct ip_vs_dh_state *s = svc->sched_data; |
| |
| /* got to clean up hash buckets here */ |
| ip_vs_dh_flush(s); |
| |
| /* release the table itself */ |
| kfree_rcu(s, rcu_head); |
| IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) released\n", |
| sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE); |
| } |
| |
| |
| static int ip_vs_dh_dest_changed(struct ip_vs_service *svc, |
| struct ip_vs_dest *dest) |
| { |
| struct ip_vs_dh_state *s = svc->sched_data; |
| |
| /* assign the hash buckets with the updated service */ |
| ip_vs_dh_reassign(s, svc); |
| |
| return 0; |
| } |
| |
| |
| /* |
| * If the dest flags is set with IP_VS_DEST_F_OVERLOAD, |
| * consider that the server is overloaded here. |
| */ |
| static inline int is_overloaded(struct ip_vs_dest *dest) |
| { |
| return dest->flags & IP_VS_DEST_F_OVERLOAD; |
| } |
| |
| |
| /* |
| * Destination hashing scheduling |
| */ |
| static struct ip_vs_dest * |
| ip_vs_dh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, |
| struct ip_vs_iphdr *iph) |
| { |
| struct ip_vs_dest *dest; |
| struct ip_vs_dh_state *s; |
| |
| IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); |
| |
| s = (struct ip_vs_dh_state *) svc->sched_data; |
| dest = ip_vs_dh_get(svc->af, s, &iph->daddr); |
| if (!dest |
| || !(dest->flags & IP_VS_DEST_F_AVAILABLE) |
| || atomic_read(&dest->weight) <= 0 |
| || is_overloaded(dest)) { |
| ip_vs_scheduler_err(svc, "no destination available"); |
| return NULL; |
| } |
| |
| IP_VS_DBG_BUF(6, "DH: destination IP address %s --> server %s:%d\n", |
| IP_VS_DBG_ADDR(svc->af, &iph->daddr), |
| IP_VS_DBG_ADDR(dest->af, &dest->addr), |
| ntohs(dest->port)); |
| |
| return dest; |
| } |
| |
| |
| /* |
| * IPVS DH Scheduler structure |
| */ |
| static struct ip_vs_scheduler ip_vs_dh_scheduler = |
| { |
| .name = "dh", |
| .refcnt = ATOMIC_INIT(0), |
| .module = THIS_MODULE, |
| .n_list = LIST_HEAD_INIT(ip_vs_dh_scheduler.n_list), |
| .init_service = ip_vs_dh_init_svc, |
| .done_service = ip_vs_dh_done_svc, |
| .add_dest = ip_vs_dh_dest_changed, |
| .del_dest = ip_vs_dh_dest_changed, |
| .schedule = ip_vs_dh_schedule, |
| }; |
| |
| |
| static int __init ip_vs_dh_init(void) |
| { |
| return register_ip_vs_scheduler(&ip_vs_dh_scheduler); |
| } |
| |
| |
| static void __exit ip_vs_dh_cleanup(void) |
| { |
| unregister_ip_vs_scheduler(&ip_vs_dh_scheduler); |
| synchronize_rcu(); |
| } |
| |
| |
| module_init(ip_vs_dh_init); |
| module_exit(ip_vs_dh_cleanup); |
| MODULE_LICENSE("GPL"); |