net/netfilter/ipvs/ip_vs

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This source file includes following definitions.
ip_vs_dh_hashkey
ip_vs_dh_get
ip_vs_dh_reassign
ip_vs_dh_flush
ip_vs_dh_init_svc
ip_vs_dh_done_svc
ip_vs_dh_dest_changed
is_overloaded
ip_vs_dh_schedule
ip_vs_dh_init
ip_vs_dh_cleanup
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * IPVS:        Destination Hashing scheduling module
   4  *
   5  * Authors:     Wensong Zhang <wensong@gnuchina.org>
   6  *
   7  *              Inspired by the consistent hashing scheduler patch from
   8  *              Thomas Proell <proellt@gmx.de>
   9  *
  10  * Changes:
  11  */
  12 
  13 /*
  14  * The dh algorithm is to select server by the hash key of destination IP
  15  * address. The pseudo code is as follows:
  16  *
  17  *       n <- servernode[dest_ip];
  18  *       if (n is dead) OR
  19  *          (n is overloaded) OR (n.weight <= 0) then
  20  *                 return NULL;
  21  *
  22  *       return n;
  23  *
  24  * Notes that servernode is a 256-bucket hash table that maps the hash
  25  * index derived from packet destination IP address to the current server
  26  * array. If the dh scheduler is used in cache cluster, it is good to
  27  * combine it with cache_bypass feature. When the statically assigned
  28  * server is dead or overloaded, the load balancer can bypass the cache
  29  * server and send requests to the original server directly.
  30  *
  31  */
  32 
  33 #define KMSG_COMPONENT "IPVS"
  34 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  35 
  36 #include <linux/ip.h>
  37 #include <linux/slab.h>
  38 #include <linux/module.h>
  39 #include <linux/kernel.h>
  40 #include <linux/skbuff.h>
  41 #include <linux/hash.h>
  42 
  43 #include <net/ip_vs.h>
  44 
  45 
  46 /*
  47  *      IPVS DH bucket
  48  */
  49 struct ip_vs_dh_bucket {
  50         struct ip_vs_dest __rcu *dest;  /* real server (cache) */
  51 };
  52 
  53 /*
  54  *     for IPVS DH entry hash table
  55  */
  56 #ifndef CONFIG_IP_VS_DH_TAB_BITS
  57 #define CONFIG_IP_VS_DH_TAB_BITS        8
  58 #endif
  59 #define IP_VS_DH_TAB_BITS               CONFIG_IP_VS_DH_TAB_BITS
  60 #define IP_VS_DH_TAB_SIZE               (1 << IP_VS_DH_TAB_BITS)
  61 #define IP_VS_DH_TAB_MASK               (IP_VS_DH_TAB_SIZE - 1)
  62 
  63 struct ip_vs_dh_state {
  64         struct ip_vs_dh_bucket          buckets[IP_VS_DH_TAB_SIZE];
  65         struct rcu_head                 rcu_head;
  66 };
  67 
  68 /*
  69  *      Returns hash value for IPVS DH entry
  70  */
  71 static inline unsigned int ip_vs_dh_hashkey(int af, const union nf_inet_addr *addr)
  72 {
  73         __be32 addr_fold = addr->ip;
  74 
  75 #ifdef CONFIG_IP_VS_IPV6
  76         if (af == AF_INET6)
  77                 addr_fold = addr->ip6[0]^addr->ip6[1]^
  78                             addr->ip6[2]^addr->ip6[3];
  79 #endif
  80         return hash_32(ntohl(addr_fold), IP_VS_DH_TAB_BITS);
  81 }
  82 
  83 
  84 /*
  85  *      Get ip_vs_dest associated with supplied parameters.
  86  */
  87 static inline struct ip_vs_dest *
  88 ip_vs_dh_get(int af, struct ip_vs_dh_state *s, const union nf_inet_addr *addr)
  89 {
  90         return rcu_dereference(s->buckets[ip_vs_dh_hashkey(af, addr)].dest);
  91 }
  92 
  93 
  94 /*
  95  *      Assign all the hash buckets of the specified table with the service.
  96  */
  97 static int
  98 ip_vs_dh_reassign(struct ip_vs_dh_state *s, struct ip_vs_service *svc)
  99 {
 100         int i;
 101         struct ip_vs_dh_bucket *b;
 102         struct list_head *p;
 103         struct ip_vs_dest *dest;
 104         bool empty;
 105 
 106         b = &s->buckets[0];
 107         p = &svc->destinations;
 108         empty = list_empty(p);
 109         for (i=0; i<IP_VS_DH_TAB_SIZE; i++) {
 110                 dest = rcu_dereference_protected(b->dest, 1);
 111                 if (dest)
 112                         ip_vs_dest_put(dest);
 113                 if (empty)
 114                         RCU_INIT_POINTER(b->dest, NULL);
 115                 else {
 116                         if (p == &svc->destinations)
 117                                 p = p->next;
 118 
 119                         dest = list_entry(p, struct ip_vs_dest, n_list);
 120                         ip_vs_dest_hold(dest);
 121                         RCU_INIT_POINTER(b->dest, dest);
 122 
 123                         p = p->next;
 124                 }
 125                 b++;
 126         }
 127         return 0;
 128 }
 129 
 130 
 131 /*
 132  *      Flush all the hash buckets of the specified table.
 133  */
 134 static void ip_vs_dh_flush(struct ip_vs_dh_state *s)
 135 {
 136         int i;
 137         struct ip_vs_dh_bucket *b;
 138         struct ip_vs_dest *dest;
 139 
 140         b = &s->buckets[0];
 141         for (i=0; i<IP_VS_DH_TAB_SIZE; i++) {
 142                 dest = rcu_dereference_protected(b->dest, 1);
 143                 if (dest) {
 144                         ip_vs_dest_put(dest);
 145                         RCU_INIT_POINTER(b->dest, NULL);
 146                 }
 147                 b++;
 148         }
 149 }
 150 
 151 
 152 static int ip_vs_dh_init_svc(struct ip_vs_service *svc)
 153 {
 154         struct ip_vs_dh_state *s;
 155 
 156         /* allocate the DH table for this service */
 157         s = kzalloc(sizeof(struct ip_vs_dh_state), GFP_KERNEL);
 158         if (s == NULL)
 159                 return -ENOMEM;
 160 
 161         svc->sched_data = s;
 162         IP_VS_DBG(6, "DH hash table (memory=%zdbytes) allocated for "
 163                   "current service\n",
 164                   sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE);
 165 
 166         /* assign the hash buckets with current dests */
 167         ip_vs_dh_reassign(s, svc);
 168 
 169         return 0;
 170 }
 171 
 172 
 173 static void ip_vs_dh_done_svc(struct ip_vs_service *svc)
 174 {
 175         struct ip_vs_dh_state *s = svc->sched_data;
 176 
 177         /* got to clean up hash buckets here */
 178         ip_vs_dh_flush(s);
 179 
 180         /* release the table itself */
 181         kfree_rcu(s, rcu_head);
 182         IP_VS_DBG(6, "DH hash table (memory=%zdbytes) released\n",
 183                   sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE);
 184 }
 185 
 186 
 187 static int ip_vs_dh_dest_changed(struct ip_vs_service *svc,
 188                                  struct ip_vs_dest *dest)
 189 {
 190         struct ip_vs_dh_state *s = svc->sched_data;
 191 
 192         /* assign the hash buckets with the updated service */
 193         ip_vs_dh_reassign(s, svc);
 194 
 195         return 0;
 196 }
 197 
 198 
 199 /*
 200  *      If the dest flags is set with IP_VS_DEST_F_OVERLOAD,
 201  *      consider that the server is overloaded here.
 202  */
 203 static inline int is_overloaded(struct ip_vs_dest *dest)
 204 {
 205         return dest->flags & IP_VS_DEST_F_OVERLOAD;
 206 }
 207 
 208 
 209 /*
 210  *      Destination hashing scheduling
 211  */
 212 static struct ip_vs_dest *
 213 ip_vs_dh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
 214                   struct ip_vs_iphdr *iph)
 215 {
 216         struct ip_vs_dest *dest;
 217         struct ip_vs_dh_state *s;
 218 
 219         IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
 220 
 221         s = (struct ip_vs_dh_state *) svc->sched_data;
 222         dest = ip_vs_dh_get(svc->af, s, &iph->daddr);
 223         if (!dest
 224             || !(dest->flags & IP_VS_DEST_F_AVAILABLE)
 225             || atomic_read(&dest->weight) <= 0
 226             || is_overloaded(dest)) {
 227                 ip_vs_scheduler_err(svc, "no destination available");
 228                 return NULL;
 229         }
 230 
 231         IP_VS_DBG_BUF(6, "DH: destination IP address %s --> server %s:%d\n",
 232                       IP_VS_DBG_ADDR(svc->af, &iph->daddr),
 233                       IP_VS_DBG_ADDR(dest->af, &dest->addr),
 234                       ntohs(dest->port));
 235 
 236         return dest;
 237 }
 238 
 239 
 240 /*
 241  *      IPVS DH Scheduler structure
 242  */
 243 static struct ip_vs_scheduler ip_vs_dh_scheduler =
 244 {
 245         .name =                 "dh",
 246         .refcnt =               ATOMIC_INIT(0),
 247         .module =               THIS_MODULE,
 248         .n_list =               LIST_HEAD_INIT(ip_vs_dh_scheduler.n_list),
 249         .init_service =         ip_vs_dh_init_svc,
 250         .done_service =         ip_vs_dh_done_svc,
 251         .add_dest =             ip_vs_dh_dest_changed,
 252         .del_dest =             ip_vs_dh_dest_changed,
 253         .schedule =             ip_vs_dh_schedule,
 254 };
 255 
 256 
 257 static int __init ip_vs_dh_init(void)
 258 {
 259         return register_ip_vs_scheduler(&ip_vs_dh_scheduler);
 260 }
 261 
 262 
 263 static void __exit ip_vs_dh_cleanup(void)
 264 {
 265         unregister_ip_vs_scheduler(&ip_vs_dh_scheduler);
 266         synchronize_rcu();
 267 }
 268 
 269 
 270 module_init(ip_vs_dh_init);
 271 module_exit(ip_vs_dh_cleanup);
 272 MODULE_LICENSE("GPL");
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root/net/netfilter/ipvs/ip_vs_dh.c

DEFINITIONS
