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cb7f6a7b JV |
1 | /* |
2 | * IPVS: Destination Hashing scheduling module | |
3 | * | |
4 | * Authors: Wensong Zhang <wensong@gnuchina.org> | |
5 | * | |
6 | * Inspired by the consistent hashing scheduler patch from | |
7 | * Thomas Proell <proellt@gmx.de> | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU General Public License | |
11 | * as published by the Free Software Foundation; either version | |
12 | * 2 of the License, or (at your option) any later version. | |
13 | * | |
14 | * Changes: | |
15 | * | |
16 | */ | |
17 | ||
18 | /* | |
19 | * The dh algorithm is to select server by the hash key of destination IP | |
20 | * address. The pseudo code is as follows: | |
21 | * | |
22 | * n <- servernode[dest_ip]; | |
23 | * if (n is dead) OR | |
24 | * (n is overloaded) OR (n.weight <= 0) then | |
25 | * return NULL; | |
26 | * | |
27 | * return n; | |
28 | * | |
29 | * Notes that servernode is a 256-bucket hash table that maps the hash | |
30 | * index derived from packet destination IP address to the current server | |
31 | * array. If the dh scheduler is used in cache cluster, it is good to | |
32 | * combine it with cache_bypass feature. When the statically assigned | |
33 | * server is dead or overloaded, the load balancer can bypass the cache | |
34 | * server and send requests to the original server directly. | |
35 | * | |
36 | */ | |
37 | ||
9aada7ac HE |
38 | #define KMSG_COMPONENT "IPVS" |
39 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt | |
40 | ||
cb7f6a7b | 41 | #include <linux/ip.h> |
5a0e3ad6 | 42 | #include <linux/slab.h> |
cb7f6a7b JV |
43 | #include <linux/module.h> |
44 | #include <linux/kernel.h> | |
45 | #include <linux/skbuff.h> | |
46 | ||
47 | #include <net/ip_vs.h> | |
48 | ||
49 | ||
50 | /* | |
51 | * IPVS DH bucket | |
52 | */ | |
53 | struct ip_vs_dh_bucket { | |
8f3d0023 | 54 | struct ip_vs_dest __rcu *dest; /* real server (cache) */ |
cb7f6a7b JV |
55 | }; |
56 | ||
57 | /* | |
58 | * for IPVS DH entry hash table | |
59 | */ | |
60 | #ifndef CONFIG_IP_VS_DH_TAB_BITS | |
61 | #define CONFIG_IP_VS_DH_TAB_BITS 8 | |
62 | #endif | |
63 | #define IP_VS_DH_TAB_BITS CONFIG_IP_VS_DH_TAB_BITS | |
64 | #define IP_VS_DH_TAB_SIZE (1 << IP_VS_DH_TAB_BITS) | |
65 | #define IP_VS_DH_TAB_MASK (IP_VS_DH_TAB_SIZE - 1) | |
66 | ||
8f3d0023 JA |
67 | struct ip_vs_dh_state { |
68 | struct ip_vs_dh_bucket buckets[IP_VS_DH_TAB_SIZE]; | |
69 | struct rcu_head rcu_head; | |
70 | }; | |
cb7f6a7b JV |
71 | |
72 | /* | |
73 | * Returns hash value for IPVS DH entry | |
74 | */ | |
95c96174 | 75 | static inline unsigned int ip_vs_dh_hashkey(int af, const union nf_inet_addr *addr) |
cb7f6a7b | 76 | { |
20971a0a JV |
77 | __be32 addr_fold = addr->ip; |
78 | ||
79 | #ifdef CONFIG_IP_VS_IPV6 | |
80 | if (af == AF_INET6) | |
81 | addr_fold = addr->ip6[0]^addr->ip6[1]^ | |
82 | addr->ip6[2]^addr->ip6[3]; | |
83 | #endif | |
84 | return (ntohl(addr_fold)*2654435761UL) & IP_VS_DH_TAB_MASK; | |
cb7f6a7b JV |
85 | } |
86 | ||
87 | ||
88 | /* | |
89 | * Get ip_vs_dest associated with supplied parameters. | |
90 | */ | |
91 | static inline struct ip_vs_dest * | |
8f3d0023 | 92 | ip_vs_dh_get(int af, struct ip_vs_dh_state *s, const union nf_inet_addr *addr) |
cb7f6a7b | 93 | { |
8f3d0023 | 94 | return rcu_dereference(s->buckets[ip_vs_dh_hashkey(af, addr)].dest); |
cb7f6a7b JV |
95 | } |
96 | ||
97 | ||
98 | /* | |
99 | * Assign all the hash buckets of the specified table with the service. | |
100 | */ | |
101 | static int | |
8f3d0023 | 102 | ip_vs_dh_reassign(struct ip_vs_dh_state *s, struct ip_vs_service *svc) |
cb7f6a7b JV |
103 | { |
104 | int i; | |
105 | struct ip_vs_dh_bucket *b; | |
106 | struct list_head *p; | |
107 | struct ip_vs_dest *dest; | |
8f3d0023 | 108 | bool empty; |
cb7f6a7b | 109 | |
8f3d0023 | 110 | b = &s->buckets[0]; |
cb7f6a7b | 111 | p = &svc->destinations; |
8f3d0023 | 112 | empty = list_empty(p); |
cb7f6a7b | 113 | for (i=0; i<IP_VS_DH_TAB_SIZE; i++) { |
8f3d0023 JA |
114 | dest = rcu_dereference_protected(b->dest, 1); |
115 | if (dest) | |
116 | ip_vs_dest_put(dest); | |
117 | if (empty) | |
118 | RCU_INIT_POINTER(b->dest, NULL); | |
119 | else { | |
cb7f6a7b JV |
120 | if (p == &svc->destinations) |
121 | p = p->next; | |
122 | ||
123 | dest = list_entry(p, struct ip_vs_dest, n_list); | |
8f3d0023 JA |
124 | ip_vs_dest_hold(dest); |
125 | RCU_INIT_POINTER(b->dest, dest); | |
cb7f6a7b JV |
126 | |
127 | p = p->next; | |
128 | } | |
129 | b++; | |
130 | } | |
131 | return 0; | |
132 | } | |
133 | ||
134 | ||
135 | /* | |
136 | * Flush all the hash buckets of the specified table. | |
137 | */ | |
8f3d0023 | 138 | static void ip_vs_dh_flush(struct ip_vs_dh_state *s) |
cb7f6a7b JV |
139 | { |
140 | int i; | |
141 | struct ip_vs_dh_bucket *b; | |
8f3d0023 | 142 | struct ip_vs_dest *dest; |
cb7f6a7b | 143 | |
8f3d0023 | 144 | b = &s->buckets[0]; |
cb7f6a7b | 145 | for (i=0; i<IP_VS_DH_TAB_SIZE; i++) { |
8f3d0023 JA |
146 | dest = rcu_dereference_protected(b->dest, 1); |
147 | if (dest) { | |
148 | ip_vs_dest_put(dest); | |
149 | RCU_INIT_POINTER(b->dest, NULL); | |
cb7f6a7b JV |
150 | } |
151 | b++; | |
152 | } | |
153 | } | |
154 | ||
155 | ||
156 | static int ip_vs_dh_init_svc(struct ip_vs_service *svc) | |
157 | { | |
8f3d0023 | 158 | struct ip_vs_dh_state *s; |
cb7f6a7b JV |
159 | |
160 | /* allocate the DH table for this service */ | |
8f3d0023 JA |
161 | s = kzalloc(sizeof(struct ip_vs_dh_state), GFP_KERNEL); |
162 | if (s == NULL) | |
cb7f6a7b | 163 | return -ENOMEM; |
0a9ee813 | 164 | |
8f3d0023 | 165 | svc->sched_data = s; |
cb7f6a7b JV |
166 | IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) allocated for " |
167 | "current service\n", | |
168 | sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE); | |
169 | ||
8f3d0023 JA |
170 | /* assign the hash buckets with current dests */ |
171 | ip_vs_dh_reassign(s, svc); | |
cb7f6a7b JV |
172 | |
173 | return 0; | |
174 | } | |
175 | ||
176 | ||
ed3ffc4e | 177 | static void ip_vs_dh_done_svc(struct ip_vs_service *svc) |
cb7f6a7b | 178 | { |
8f3d0023 | 179 | struct ip_vs_dh_state *s = svc->sched_data; |
cb7f6a7b JV |
180 | |
181 | /* got to clean up hash buckets here */ | |
8f3d0023 | 182 | ip_vs_dh_flush(s); |
cb7f6a7b JV |
183 | |
184 | /* release the table itself */ | |
8f3d0023 | 185 | kfree_rcu(s, rcu_head); |
cb7f6a7b JV |
186 | IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) released\n", |
187 | sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE); | |
cb7f6a7b JV |
188 | } |
189 | ||
190 | ||
8f3d0023 JA |
191 | static int ip_vs_dh_dest_changed(struct ip_vs_service *svc, |
192 | struct ip_vs_dest *dest) | |
cb7f6a7b | 193 | { |
8f3d0023 | 194 | struct ip_vs_dh_state *s = svc->sched_data; |
cb7f6a7b JV |
195 | |
196 | /* assign the hash buckets with the updated service */ | |
8f3d0023 | 197 | ip_vs_dh_reassign(s, svc); |
cb7f6a7b JV |
198 | |
199 | return 0; | |
200 | } | |
201 | ||
202 | ||
203 | /* | |
204 | * If the dest flags is set with IP_VS_DEST_F_OVERLOAD, | |
205 | * consider that the server is overloaded here. | |
206 | */ | |
207 | static inline int is_overloaded(struct ip_vs_dest *dest) | |
208 | { | |
209 | return dest->flags & IP_VS_DEST_F_OVERLOAD; | |
210 | } | |
211 | ||
212 | ||
213 | /* | |
214 | * Destination hashing scheduling | |
215 | */ | |
216 | static struct ip_vs_dest * | |
bba54de5 JA |
217 | ip_vs_dh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, |
218 | struct ip_vs_iphdr *iph) | |
cb7f6a7b JV |
219 | { |
220 | struct ip_vs_dest *dest; | |
8f3d0023 | 221 | struct ip_vs_dh_state *s; |
cb7f6a7b | 222 | |
1e3e238e | 223 | IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); |
cb7f6a7b | 224 | |
8f3d0023 | 225 | s = (struct ip_vs_dh_state *) svc->sched_data; |
bba54de5 | 226 | dest = ip_vs_dh_get(svc->af, s, &iph->daddr); |
cb7f6a7b JV |
227 | if (!dest |
228 | || !(dest->flags & IP_VS_DEST_F_AVAILABLE) | |
229 | || atomic_read(&dest->weight) <= 0 | |
230 | || is_overloaded(dest)) { | |
8f3d0023 | 231 | ip_vs_scheduler_err(svc, "no destination available"); |
cb7f6a7b JV |
232 | return NULL; |
233 | } | |
234 | ||
20971a0a | 235 | IP_VS_DBG_BUF(6, "DH: destination IP address %s --> server %s:%d\n", |
bba54de5 | 236 | IP_VS_DBG_ADDR(svc->af, &iph->daddr), |
4d316f3f | 237 | IP_VS_DBG_ADDR(dest->af, &dest->addr), |
20971a0a | 238 | ntohs(dest->port)); |
cb7f6a7b JV |
239 | |
240 | return dest; | |
241 | } | |
242 | ||
243 | ||
244 | /* | |
245 | * IPVS DH Scheduler structure | |
246 | */ | |
247 | static struct ip_vs_scheduler ip_vs_dh_scheduler = | |
248 | { | |
249 | .name = "dh", | |
250 | .refcnt = ATOMIC_INIT(0), | |
251 | .module = THIS_MODULE, | |
252 | .n_list = LIST_HEAD_INIT(ip_vs_dh_scheduler.n_list), | |
cb7f6a7b JV |
253 | .init_service = ip_vs_dh_init_svc, |
254 | .done_service = ip_vs_dh_done_svc, | |
8f3d0023 JA |
255 | .add_dest = ip_vs_dh_dest_changed, |
256 | .del_dest = ip_vs_dh_dest_changed, | |
cb7f6a7b JV |
257 | .schedule = ip_vs_dh_schedule, |
258 | }; | |
259 | ||
260 | ||
261 | static int __init ip_vs_dh_init(void) | |
262 | { | |
263 | return register_ip_vs_scheduler(&ip_vs_dh_scheduler); | |
264 | } | |
265 | ||
266 | ||
267 | static void __exit ip_vs_dh_cleanup(void) | |
268 | { | |
269 | unregister_ip_vs_scheduler(&ip_vs_dh_scheduler); | |
ceec4c38 | 270 | synchronize_rcu(); |
cb7f6a7b JV |
271 | } |
272 | ||
273 | ||
274 | module_init(ip_vs_dh_init); | |
275 | module_exit(ip_vs_dh_cleanup); | |
276 | MODULE_LICENSE("GPL"); |