net/netfilter/ipvs/ip_vs_lblcr.c

   1 /*
   2  * IPVS:        Locality-Based Least-Connection with Replication scheduler
   3  *
   4  * Authors:     Wensong Zhang <wensong@gnuchina.org>
   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  *     Julian Anastasov        :    Added the missing (dest->weight>0)
  13  *                                  condition in the ip_vs_dest_set_max.
  14  *
  15  */
  16
  17 /*
  18  * The lblc/r algorithm is as follows (pseudo code):
  19  *
  20  *       if serverSet[dest_ip] is null then
  21  *               n, serverSet[dest_ip] <- {weighted least-conn node};
  22  *       else
  23  *               n <- {least-conn (alive) node in serverSet[dest_ip]};
  24  *               if (n is null) OR
  25  *                  (n.conns>n.weight AND
  26  *                   there is a node m with m.conns<m.weight/2) then
  27  *                   n <- {weighted least-conn node};
  28  *                   add n to serverSet[dest_ip];
  29  *               if |serverSet[dest_ip]| > 1 AND
  30  *                   now - serverSet[dest_ip].lastMod > T then
  31  *                   m <- {most conn node in serverSet[dest_ip]};
  32  *                   remove m from serverSet[dest_ip];
  33  *       if serverSet[dest_ip] changed then
  34  *               serverSet[dest_ip].lastMod <- now;
  35  *
  36  *       return n;
  37  *
  38  */
  39
  40 #define KMSG_COMPONENT "IPVS"
  41 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  42
  43 #include <linux/ip.h>
  44 #include <linux/module.h>
  45 #include <linux/kernel.h>
  46 #include <linux/skbuff.h>
  47 #include <linux/jiffies.h>
  48 #include <linux/list.h>
  49 #include <linux/slab.h>
  50
  51 /* for sysctl */
  52 #include <linux/fs.h>
  53 #include <linux/sysctl.h>
  54 #include <net/net_namespace.h>
  55
  56 #include <net/ip_vs.h>
  57
  58
  59 /*
  60  *    It is for garbage collection of stale IPVS lblcr entries,
  61  *    when the table is full.
  62  */
  63 #define CHECK_EXPIRE_INTERVAL   (60*HZ)
  64 #define ENTRY_TIMEOUT           (6*60*HZ)
  65
  66 /*
  67  *    It is for full expiration check.
  68  *    When there is no partial expiration check (garbage collection)
  69  *    in a half hour, do a full expiration check to collect stale
  70  *    entries that haven't been touched for a day.
  71  */
  72 #define COUNT_FOR_FULL_EXPIRATION   30
  73
  74 /*
  75  *     for IPVS lblcr entry hash table
  76  */
  77 #ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
  78 #define CONFIG_IP_VS_LBLCR_TAB_BITS      10
  79 #endif
  80 #define IP_VS_LBLCR_TAB_BITS     CONFIG_IP_VS_LBLCR_TAB_BITS
  81 #define IP_VS_LBLCR_TAB_SIZE     (1 << IP_VS_LBLCR_TAB_BITS)
  82 #define IP_VS_LBLCR_TAB_MASK     (IP_VS_LBLCR_TAB_SIZE - 1)
  83
  84
  85 /*
  86  *      IPVS destination set structure and operations
  87  */
  88 struct ip_vs_dest_set_elem {
  89         struct list_head        list;          /* list link */
  90         struct ip_vs_dest       *dest;          /* destination server */
  91 };
  92
  93 struct ip_vs_dest_set {
  94         atomic_t                size;           /* set size */
  95         unsigned long           lastmod;        /* last modified time */
  96         struct list_head        list;           /* destination list */
  97         rwlock_t                lock;           /* lock for this list */
  98 };
  99
 100
 101 static struct ip_vs_dest_set_elem *
 102 ip_vs_dest_set_insert(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 103 {
 104         struct ip_vs_dest_set_elem *e;
 105
 106         list_for_each_entry(e, &set->list, list) {
 107                 if (e->dest == dest)
 108                         /* already existed */
 109                         return NULL;
 110         }
 111
 112         e = kmalloc(sizeof(*e), GFP_ATOMIC);
 113         if (e == NULL) {
 114                 pr_err("%s(): no memory\n", __func__);
 115                 return NULL;
 116         }
 117
 118         atomic_inc(&dest->refcnt);
 119         e->dest = dest;
 120
 121         list_add(&e->list, &set->list);
 122         atomic_inc(&set->size);
 123
 124         set->lastmod = jiffies;
 125         return e;
 126 }
 127
 128 static void
 129 ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 130 {
 131         struct ip_vs_dest_set_elem *e;
 132
 133         list_for_each_entry(e, &set->list, list) {
 134                 if (e->dest == dest) {
 135                         /* HIT */
 136                         atomic_dec(&set->size);
 137                         set->lastmod = jiffies;
 138                         atomic_dec(&e->dest->refcnt);
 139                         list_del(&e->list);
 140                         kfree(e);
 141                         break;
 142                 }
 143         }
 144 }
 145
 146 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
 147 {
 148         struct ip_vs_dest_set_elem *e, *ep;
 149
 150         write_lock(&set->lock);
 151         list_for_each_entry_safe(e, ep, &set->list, list) {
 152                 /*
 153                  * We don't kfree dest because it is refered either
 154                  * by its service or by the trash dest list.
 155                  */
 156                 atomic_dec(&e->dest->refcnt);
 157                 list_del(&e->list);
 158                 kfree(e);
 159         }
 160         write_unlock(&set->lock);
 161 }
 162
 163 /* get weighted least-connection node in the destination set */
 164 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
 165 {
 166         register struct ip_vs_dest_set_elem *e;
 167         struct ip_vs_dest *dest, *least;
 168         int loh, doh;
 169
 170         if (set == NULL)
 171                 return NULL;
 172
 173         /* select the first destination server, whose weight > 0 */
 174         list_for_each_entry(e, &set->list, list) {
 175                 least = e->dest;
 176                 if (least->flags & IP_VS_DEST_F_OVERLOAD)
 177                         continue;
 178
 179                 if ((atomic_read(&least->weight) > 0)
 180                     && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
 181                         loh = ip_vs_dest_conn_overhead(least);
 182                         goto nextstage;
 183                 }
 184         }
 185         return NULL;
 186
 187         /* find the destination with the weighted least load */
 188   nextstage:
 189         list_for_each_entry(e, &set->list, list) {
 190                 dest = e->dest;
 191                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 192                         continue;
 193
 194                 doh = ip_vs_dest_conn_overhead(dest);
 195                 if ((loh * atomic_read(&dest->weight) >
 196                      doh * atomic_read(&least->weight))
 197                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 198                         least = dest;
 199                         loh = doh;
 200                 }
 201         }
 202
 203         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 204                       "activeconns %d refcnt %d weight %d overhead %d\n",
 205                       __func__,
 206                       IP_VS_DBG_ADDR(least->af, &least->addr),
 207                       ntohs(least->port),
 208                       atomic_read(&least->activeconns),
 209                       atomic_read(&least->refcnt),
 210                       atomic_read(&least->weight), loh);
 211         return least;
 212 }
 213
 214
 215 /* get weighted most-connection node in the destination set */
 216 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
 217 {
 218         register struct ip_vs_dest_set_elem *e;
 219         struct ip_vs_dest *dest, *most;
 220         int moh, doh;
 221
 222         if (set == NULL)
 223                 return NULL;
 224
 225         /* select the first destination server, whose weight > 0 */
 226         list_for_each_entry(e, &set->list, list) {
 227                 most = e->dest;
 228                 if (atomic_read(&most->weight) > 0) {
 229                         moh = ip_vs_dest_conn_overhead(most);
 230                         goto nextstage;
 231                 }
 232         }
 233         return NULL;
 234
 235         /* find the destination with the weighted most load */
 236   nextstage:
 237         list_for_each_entry(e, &set->list, list) {
 238                 dest = e->dest;
 239                 doh = ip_vs_dest_conn_overhead(dest);
 240                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
 241                 if ((moh * atomic_read(&dest->weight) <
 242                      doh * atomic_read(&most->weight))
 243                     && (atomic_read(&dest->weight) > 0)) {
 244                         most = dest;
 245                         moh = doh;
 246                 }
 247         }
 248
 249         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 250                       "activeconns %d refcnt %d weight %d overhead %d\n",
 251                       __func__,
 252                       IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
 253                       atomic_read(&most->activeconns),
 254                       atomic_read(&most->refcnt),
 255                       atomic_read(&most->weight), moh);
 256         return most;
 257 }
 258
 259
 260 /*
 261  *      IPVS lblcr entry represents an association between destination
 262  *      IP address and its destination server set
 263  */
 264 struct ip_vs_lblcr_entry {
 265         struct list_head        list;
 266         int                     af;             /* address family */
 267         union nf_inet_addr      addr;           /* destination IP address */
 268         struct ip_vs_dest_set   set;            /* destination server set */
 269         unsigned long           lastuse;        /* last used time */
 270 };
 271
 272
 273 /*
 274  *      IPVS lblcr hash table
 275  */
 276 struct ip_vs_lblcr_table {
 277         struct list_head        bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
 278         atomic_t                entries;        /* number of entries */
 279         int                     max_size;       /* maximum size of entries */
 280         struct timer_list       periodic_timer; /* collect stale entries */
 281         int                     rover;          /* rover for expire check */
 282         int                     counter;        /* counter for no expire */
 283 };
 284
 285
 286 /*
 287  *      IPVS LBLCR sysctl table
 288  */
 289
 290 static ctl_table vs_vars_table[] = {
 291         {
 292                 .procname       = "lblcr_expiration",
 293                 .data           = NULL,
 294                 .maxlen         = sizeof(int),
 295                 .mode           = 0644,
 296                 .proc_handler   = proc_dointvec_jiffies,
 297         },
 298         { }
 299 };
 300
 301 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
 302 {
 303         list_del(&en->list);
 304         ip_vs_dest_set_eraseall(&en->set);
 305         kfree(en);
 306 }
 307
 308
 309 /*
 310  *      Returns hash value for IPVS LBLCR entry
 311  */
 312 static inline unsigned
 313 ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
 314 {
 315         __be32 addr_fold = addr->ip;
 316
 317 #ifdef CONFIG_IP_VS_IPV6
 318         if (af == AF_INET6)
 319                 addr_fold = addr->ip6[0]^addr->ip6[1]^
 320                             addr->ip6[2]^addr->ip6[3];
 321 #endif
 322         return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
 323 }
 324
 325
 326 /*
 327  *      Hash an entry in the ip_vs_lblcr_table.
 328  *      returns bool success.
 329  */
 330 static void
 331 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
 332 {
 333         unsigned hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
 334
 335         list_add(&en->list, &tbl->bucket[hash]);
 336         atomic_inc(&tbl->entries);
 337 }
 338
 339
 340 /*
 341  *  Get ip_vs_lblcr_entry associated with supplied parameters. Called under
 342  *  read lock.
 343  */
 344 static inline struct ip_vs_lblcr_entry *
 345 ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
 346                 const union nf_inet_addr *addr)
 347 {
 348         unsigned hash = ip_vs_lblcr_hashkey(af, addr);
 349         struct ip_vs_lblcr_entry *en;
 350
 351         list_for_each_entry(en, &tbl->bucket[hash], list)
 352                 if (ip_vs_addr_equal(af, &en->addr, addr))
 353                         return en;
 354
 355         return NULL;
 356 }
 357
 358
 359 /*
 360  * Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
 361  * IP address to a server. Called under write lock.
 362  */
 363 static inline struct ip_vs_lblcr_entry *
 364 ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
 365                 struct ip_vs_dest *dest)
 366 {
 367         struct ip_vs_lblcr_entry *en;
 368
 369         en = ip_vs_lblcr_get(dest->af, tbl, daddr);
 370         if (!en) {
 371                 en = kmalloc(sizeof(*en), GFP_ATOMIC);
 372                 if (!en) {
 373                         pr_err("%s(): no memory\n", __func__);
 374                         return NULL;
 375                 }
 376
 377                 en->af = dest->af;
 378                 ip_vs_addr_copy(dest->af, &en->addr, daddr);
 379                 en->lastuse = jiffies;
 380
 381                 /* initialize its dest set */
 382                 atomic_set(&(en->set.size), 0);
 383                 INIT_LIST_HEAD(&en->set.list);
 384                 rwlock_init(&en->set.lock);
 385
 386                 ip_vs_lblcr_hash(tbl, en);
 387         }
 388
 389         write_lock(&en->set.lock);
 390         ip_vs_dest_set_insert(&en->set, dest);
 391         write_unlock(&en->set.lock);
 392
 393         return en;
 394 }
 395
 396
 397 /*
 398  *      Flush all the entries of the specified table.
 399  */
 400 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
 401 {
 402         int i;
 403         struct ip_vs_lblcr_entry *en, *nxt;
 404
 405         /* No locking required, only called during cleanup. */
 406         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 407                 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
 408                         ip_vs_lblcr_free(en);
 409                 }
 410         }
 411 }
 412
 413
 414 static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
 415 {
 416         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 417         unsigned long now = jiffies;
 418         int i, j;
 419         struct ip_vs_lblcr_entry *en, *nxt;
 420         struct netns_ipvs *ipvs = net_ipvs(svc->net);
 421
 422         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 423                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 424
 425                 write_lock(&svc->sched_lock);
 426                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 427                         if (time_after(en->lastuse
 428                                         + ipvs->sysctl_lblcr_expiration, now))
 429                                 continue;
 430
 431                         ip_vs_lblcr_free(en);
 432                         atomic_dec(&tbl->entries);
 433                 }
 434                 write_unlock(&svc->sched_lock);
 435         }
 436         tbl->rover = j;
 437 }
 438
 439
 440 /*
 441  *      Periodical timer handler for IPVS lblcr table
 442  *      It is used to collect stale entries when the number of entries
 443  *      exceeds the maximum size of the table.
 444  *
 445  *      Fixme: we probably need more complicated algorithm to collect
 446  *             entries that have not been used for a long time even
 447  *             if the number of entries doesn't exceed the maximum size
 448  *             of the table.
 449  *      The full expiration check is for this purpose now.
 450  */
 451 static void ip_vs_lblcr_check_expire(unsigned long data)
 452 {
 453         struct ip_vs_service *svc = (struct ip_vs_service *) data;
 454         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 455         unsigned long now = jiffies;
 456         int goal;
 457         int i, j;
 458         struct ip_vs_lblcr_entry *en, *nxt;
 459
 460         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
 461                 /* do full expiration check */
 462                 ip_vs_lblcr_full_check(svc);
 463                 tbl->counter = 1;
 464                 goto out;
 465         }
 466
 467         if (atomic_read(&tbl->entries) <= tbl->max_size) {
 468                 tbl->counter++;
 469                 goto out;
 470         }
 471
 472         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
 473         if (goal > tbl->max_size/2)
 474                 goal = tbl->max_size/2;
 475
 476         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 477                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 478
 479                 write_lock(&svc->sched_lock);
 480                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 481                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
 482                                 continue;
 483
 484                         ip_vs_lblcr_free(en);
 485                         atomic_dec(&tbl->entries);
 486                         goal--;
 487                 }
 488                 write_unlock(&svc->sched_lock);
 489                 if (goal <= 0)
 490                         break;
 491         }
 492         tbl->rover = j;
 493
 494   out:
 495         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
 496 }
 497
 498 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
 499 {
 500         int i;
 501         struct ip_vs_lblcr_table *tbl;
 502
 503         /*
 504          *    Allocate the ip_vs_lblcr_table for this service
 505          */
 506         tbl = kmalloc(sizeof(*tbl), GFP_ATOMIC);
 507         if (tbl == NULL) {
 508                 pr_err("%s(): no memory\n", __func__);
 509                 return -ENOMEM;
 510         }
 511         svc->sched_data = tbl;
 512         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
 513                   "current service\n", sizeof(*tbl));
 514
 515         /*
 516          *    Initialize the hash buckets
 517          */
 518         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 519                 INIT_LIST_HEAD(&tbl->bucket[i]);
 520         }
 521         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
 522         tbl->rover = 0;
 523         tbl->counter = 1;
 524
 525         /*
 526          *    Hook periodic timer for garbage collection
 527          */
 528         setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
 529                         (unsigned long)svc);
 530         mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
 531
 532         return 0;
 533 }
 534
 535
 536 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
 537 {
 538         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 539
 540         /* remove periodic timer */
 541         del_timer_sync(&tbl->periodic_timer);
 542
 543         /* got to clean up table entries here */
 544         ip_vs_lblcr_flush(tbl);
 545
 546         /* release the table itself */
 547         kfree(tbl);
 548         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
 549                   sizeof(*tbl));
 550
 551         return 0;
 552 }
 553
 554
 555 static inline struct ip_vs_dest *
 556 __ip_vs_lblcr_schedule(struct ip_vs_service *svc)
 557 {
 558         struct ip_vs_dest *dest, *least;
 559         int loh, doh;
 560
 561         /*
 562          * We use the following formula to estimate the load:
 563          *                (dest overhead) / dest->weight
 564          *
 565          * Remember -- no floats in kernel mode!!!
 566          * The comparison of h1*w2 > h2*w1 is equivalent to that of
 567          *                h1/w1 > h2/w2
 568          * if every weight is larger than zero.
 569          *
 570          * The server with weight=0 is quiesced and will not receive any
 571          * new connection.
 572          */
 573         list_for_each_entry(dest, &svc->destinations, n_list) {
 574                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 575                         continue;
 576
 577                 if (atomic_read(&dest->weight) > 0) {
 578                         least = dest;
 579                         loh = ip_vs_dest_conn_overhead(least);
 580                         goto nextstage;
 581                 }
 582         }
 583         return NULL;
 584
 585         /*
 586          *    Find the destination with the least load.
 587          */
 588   nextstage:
 589         list_for_each_entry_continue(dest, &svc->destinations, n_list) {
 590                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 591                         continue;
 592
 593                 doh = ip_vs_dest_conn_overhead(dest);
 594                 if (loh * atomic_read(&dest->weight) >
 595                     doh * atomic_read(&least->weight)) {
 596                         least = dest;
 597                         loh = doh;
 598                 }
 599         }
 600
 601         IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
 602                       "activeconns %d refcnt %d weight %d overhead %d\n",
 603                       IP_VS_DBG_ADDR(least->af, &least->addr),
 604                       ntohs(least->port),
 605                       atomic_read(&least->activeconns),
 606                       atomic_read(&least->refcnt),
 607                       atomic_read(&least->weight), loh);
 608
 609         return least;
 610 }
 611
 612
 613 /*
 614  *   If this destination server is overloaded and there is a less loaded
 615  *   server, then return true.
 616  */
 617 static inline int
 618 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
 619 {
 620         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
 621                 struct ip_vs_dest *d;
 622
 623                 list_for_each_entry(d, &svc->destinations, n_list) {
 624                         if (atomic_read(&d->activeconns)*2
 625                             < atomic_read(&d->weight)) {
 626                                 return 1;
 627                         }
 628                 }
 629         }
 630         return 0;
 631 }
 632
 633
 634 /*
 635  *    Locality-Based (weighted) Least-Connection scheduling
 636  */
 637 static struct ip_vs_dest *
 638 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 639 {
 640         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 641         struct ip_vs_iphdr iph;
 642         struct ip_vs_dest *dest = NULL;
 643         struct ip_vs_lblcr_entry *en;
 644
 645         ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);
 646
 647         IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
 648
 649         /* First look in our cache */
 650         read_lock(&svc->sched_lock);
 651         en = ip_vs_lblcr_get(svc->af, tbl, &iph.daddr);
 652         if (en) {
 653                 struct netns_ipvs *ipvs = net_ipvs(svc->net);
 654                 /* We only hold a read lock, but this is atomic */
 655                 en->lastuse = jiffies;
 656
 657                 /* Get the least loaded destination */
 658                 read_lock(&en->set.lock);
 659                 dest = ip_vs_dest_set_min(&en->set);
 660                 read_unlock(&en->set.lock);
 661
 662                 /* More than one destination + enough time passed by, cleanup */
 663                 if (atomic_read(&en->set.size) > 1 &&
 664                                 time_after(jiffies, en->set.lastmod +
 665                                 ipvs->sysctl_lblcr_expiration)) {
 666                         struct ip_vs_dest *m;
 667
 668                         write_lock(&en->set.lock);
 669                         m = ip_vs_dest_set_max(&en->set);
 670                         if (m)
 671                                 ip_vs_dest_set_erase(&en->set, m);
 672                         write_unlock(&en->set.lock);
 673                 }
 674
 675                 /* If the destination is not overloaded, use it */
 676                 if (dest && !is_overloaded(dest, svc)) {
 677                         read_unlock(&svc->sched_lock);
 678                         goto out;
 679                 }
 680
 681                 /* The cache entry is invalid, time to schedule */
 682                 dest = __ip_vs_lblcr_schedule(svc);
 683                 if (!dest) {
 684                         ip_vs_scheduler_err(svc, "no destination available");
 685                         read_unlock(&svc->sched_lock);
 686                         return NULL;
 687                 }
 688
 689                 /* Update our cache entry */
 690                 write_lock(&en->set.lock);
 691                 ip_vs_dest_set_insert(&en->set, dest);
 692                 write_unlock(&en->set.lock);
 693         }
 694         read_unlock(&svc->sched_lock);
 695
 696         if (dest)
 697                 goto out;
 698
 699         /* No cache entry, time to schedule */
 700         dest = __ip_vs_lblcr_schedule(svc);
 701         if (!dest) {
 702                 IP_VS_DBG(1, "no destination available\n");
 703                 return NULL;
 704         }
 705
 706         /* If we fail to create a cache entry, we'll just use the valid dest */
 707         write_lock(&svc->sched_lock);
 708         ip_vs_lblcr_new(tbl, &iph.daddr, dest);
 709         write_unlock(&svc->sched_lock);
 710
 711 out:
 712         IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
 713                       IP_VS_DBG_ADDR(svc->af, &iph.daddr),
 714                       IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port));
 715
 716         return dest;
 717 }
 718
 719
 720 /*
 721  *      IPVS LBLCR Scheduler structure
 722  */
 723 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
 724 {
 725         .name =                 "lblcr",
 726         .refcnt =               ATOMIC_INIT(0),
 727         .module =               THIS_MODULE,
 728         .n_list =               LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
 729         .init_service =         ip_vs_lblcr_init_svc,
 730         .done_service =         ip_vs_lblcr_done_svc,
 731         .schedule =             ip_vs_lblcr_schedule,
 732 };
 733
 734 /*
 735  *  per netns init.
 736  */
 737 static int __net_init __ip_vs_lblcr_init(struct net *net)
 738 {
 739         struct netns_ipvs *ipvs = net_ipvs(net);
 740
 741         if (!net_eq(net, &init_net)) {
 742                 ipvs->lblcr_ctl_table = kmemdup(vs_vars_table,
 743                                                 sizeof(vs_vars_table),
 744                                                 GFP_KERNEL);
 745                 if (ipvs->lblcr_ctl_table == NULL)
 746                         return -ENOMEM;
 747         } else
 748                 ipvs->lblcr_ctl_table = vs_vars_table;
 749         ipvs->sysctl_lblcr_expiration = 24*60*60*HZ;
 750         ipvs->lblcr_ctl_table[0].data = &ipvs->sysctl_lblcr_expiration;
 751
 752 #ifdef CONFIG_SYSCTL
 753         ipvs->lblcr_ctl_header =
 754                 register_net_sysctl_table(net, net_vs_ctl_path,
 755                                           ipvs->lblcr_ctl_table);
 756         if (!ipvs->lblcr_ctl_header) {
 757                 if (!net_eq(net, &init_net))
 758                         kfree(ipvs->lblcr_ctl_table);
 759                 return -ENOMEM;
 760         }
 761 #endif
 762
 763         return 0;
 764 }
 765
 766 static void __net_exit __ip_vs_lblcr_exit(struct net *net)
 767 {
 768         struct netns_ipvs *ipvs = net_ipvs(net);
 769
 770 #ifdef CONFIG_SYSCTL
 771         unregister_net_sysctl_table(ipvs->lblcr_ctl_header);
 772 #endif
 773
 774         if (!net_eq(net, &init_net))
 775                 kfree(ipvs->lblcr_ctl_table);
 776 }
 777
 778 static struct pernet_operations ip_vs_lblcr_ops = {
 779         .init = __ip_vs_lblcr_init,
 780         .exit = __ip_vs_lblcr_exit,
 781 };
 782
 783 static int __init ip_vs_lblcr_init(void)
 784 {
 785         int ret;
 786
 787         ret = register_pernet_subsys(&ip_vs_lblcr_ops);
 788         if (ret)
 789                 return ret;
 790
 791         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 792         if (ret)
 793                 unregister_pernet_subsys(&ip_vs_lblcr_ops);
 794         return ret;
 795 }
 796
 797 static void __exit ip_vs_lblcr_cleanup(void)
 798 {
 799         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 800         unregister_pernet_subsys(&ip_vs_lblcr_ops);
 801 }
 802
 803
 804 module_init(ip_vs_lblcr_init);
 805 module_exit(ip_vs_lblcr_cleanup);
 806 MODULE_LICENSE("GPL");