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   1 /*
   2  * linux/fs/lockd/host.c
   3  *
   4  * Management for NLM peer hosts. The nlm_host struct is shared
   5  * between client and server implementation. The only reason to
   6  * do so is to reduce code bloat.
   7  *
   8  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/slab.h>
  13 #include <linux/in.h>
  14 #include <linux/in6.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/sunrpc/svc.h>
  17 #include <linux/lockd/lockd.h>
  18 #include <linux/lockd/sm_inter.h>
  19 #include <linux/mutex.h>
  20
  21 #include <net/ipv6.h>
  22
  23 #define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
  24 #define NLM_HOST_NRHASH         32
  25 #define NLM_HOST_REBIND         (60 * HZ)
  26 #define NLM_HOST_EXPIRE         (300 * HZ)
  27 #define NLM_HOST_COLLECT        (120 * HZ)
  28
  29 static struct hlist_head        nlm_hosts[NLM_HOST_NRHASH];
  30 static unsigned long            next_gc;
  31 static int                      nrhosts;
  32 static DEFINE_MUTEX(nlm_host_mutex);
  33
  34 static void                     nlm_gc_hosts(void);
  35 static struct nsm_handle        *nsm_find(const struct sockaddr *sap,
  36                                                 const size_t salen,
  37                                                 const char *hostname,
  38                                                 const size_t hostname_len,
  39                                                 const int create);
  40
  41 struct nlm_lookup_host_info {
  42         const int               server;         /* search for server|client */
  43         const struct sockaddr   *sap;           /* address to search for */
  44         const size_t            salen;          /* it's length */
  45         const unsigned short    protocol;       /* transport to search for*/
  46         const u32               version;        /* NLM version to search for */
  47         const char              *hostname;      /* remote's hostname */
  48         const size_t            hostname_len;   /* it's length */
  49         const struct sockaddr   *src_sap;       /* our address (optional) */
  50         const size_t            src_len;        /* it's length */
  51         const int               noresvport;     /* use non-priv port */
  52 };
  53
  54 /*
  55  * Hash function must work well on big- and little-endian platforms
  56  */
  57 static unsigned int __nlm_hash32(const __be32 n)
  58 {
  59         unsigned int hash = (__force u32)n ^ ((__force u32)n >> 16);
  60         return hash ^ (hash >> 8);
  61 }
  62
  63 static unsigned int __nlm_hash_addr4(const struct sockaddr *sap)
  64 {
  65         const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
  66         return __nlm_hash32(sin->sin_addr.s_addr);
  67 }
  68
  69 static unsigned int __nlm_hash_addr6(const struct sockaddr *sap)
  70 {
  71         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
  72         const struct in6_addr addr = sin6->sin6_addr;
  73         return __nlm_hash32(addr.s6_addr32[0]) ^
  74                __nlm_hash32(addr.s6_addr32[1]) ^
  75                __nlm_hash32(addr.s6_addr32[2]) ^
  76                __nlm_hash32(addr.s6_addr32[3]);
  77 }
  78
  79 static unsigned int nlm_hash_address(const struct sockaddr *sap)
  80 {
  81         unsigned int hash;
  82
  83         switch (sap->sa_family) {
  84         case AF_INET:
  85                 hash = __nlm_hash_addr4(sap);
  86                 break;
  87         case AF_INET6:
  88                 hash = __nlm_hash_addr6(sap);
  89                 break;
  90         default:
  91                 hash = 0;
  92         }
  93         return hash & (NLM_HOST_NRHASH - 1);
  94 }
  95
  96 static void nlm_clear_port(struct sockaddr *sap)
  97 {
  98         switch (sap->sa_family) {
  99         case AF_INET:
 100                 ((struct sockaddr_in *)sap)->sin_port = 0;
 101                 break;
 102         case AF_INET6:
 103                 ((struct sockaddr_in6 *)sap)->sin6_port = 0;
 104                 break;
 105         }
 106 }
 107
 108 static void nlm_display_ipv4_address(const struct sockaddr *sap, char *buf,
 109                                      const size_t len)
 110 {
 111         const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
 112         snprintf(buf, len, "%pI4", &sin->sin_addr.s_addr);
 113 }
 114
 115 static void nlm_display_ipv6_address(const struct sockaddr *sap, char *buf,
 116                                      const size_t len)
 117 {
 118         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
 119
 120         if (ipv6_addr_v4mapped(&sin6->sin6_addr))
 121                 snprintf(buf, len, "%pI4", &sin6->sin6_addr.s6_addr32[3]);
 122         else if (sin6->sin6_scope_id != 0)
 123                 snprintf(buf, len, "%pI6%%%u", &sin6->sin6_addr,
 124                                 sin6->sin6_scope_id);
 125         else
 126                 snprintf(buf, len, "%pI6", &sin6->sin6_addr);
 127 }
 128
 129 static void nlm_display_address(const struct sockaddr *sap,
 130                                 char *buf, const size_t len)
 131 {
 132         switch (sap->sa_family) {
 133         case AF_INET:
 134                 nlm_display_ipv4_address(sap, buf, len);
 135                 break;
 136         case AF_INET6:
 137                 nlm_display_ipv6_address(sap, buf, len);
 138                 break;
 139         default:
 140                 snprintf(buf, len, "unsupported address family");
 141                 break;
 142         }
 143 }
 144
 145 /*
 146  * Common host lookup routine for server & client
 147  */
 148 static struct nlm_host *nlm_lookup_host(struct nlm_lookup_host_info *ni)
 149 {
 150         struct hlist_head *chain;
 151         struct hlist_node *pos;
 152         struct nlm_host *host;
 153         struct nsm_handle *nsm = NULL;
 154
 155         mutex_lock(&nlm_host_mutex);
 156
 157         if (time_after_eq(jiffies, next_gc))
 158                 nlm_gc_hosts();
 159
 160         /* We may keep several nlm_host objects for a peer, because each
 161          * nlm_host is identified by
 162          * (address, protocol, version, server/client)
 163          * We could probably simplify this a little by putting all those
 164          * different NLM rpc_clients into one single nlm_host object.
 165          * This would allow us to have one nlm_host per address.
 166          */
 167         chain = &nlm_hosts[nlm_hash_address(ni->sap)];
 168         hlist_for_each_entry(host, pos, chain, h_hash) {
 169                 if (!nlm_cmp_addr(nlm_addr(host), ni->sap))
 170                         continue;
 171
 172                 /* See if we have an NSM handle for this client */
 173                 if (!nsm)
 174                         nsm = host->h_nsmhandle;
 175
 176                 if (host->h_proto != ni->protocol)
 177                         continue;
 178                 if (host->h_version != ni->version)
 179                         continue;
 180                 if (host->h_server != ni->server)
 181                         continue;
 182                 if (ni->server &&
 183                     !nlm_cmp_addr(nlm_srcaddr(host), ni->src_sap))
 184                         continue;
 185
 186                 /* Move to head of hash chain. */
 187                 hlist_del(&host->h_hash);
 188                 hlist_add_head(&host->h_hash, chain);
 189
 190                 nlm_get_host(host);
 191                 dprintk("lockd: nlm_lookup_host found host %s (%s)\n",
 192                                 host->h_name, host->h_addrbuf);
 193                 goto out;
 194         }
 195
 196         /*
 197          * The host wasn't in our hash table.  If we don't
 198          * have an NSM handle for it yet, create one.
 199          */
 200         if (nsm)
 201                 atomic_inc(&nsm->sm_count);
 202         else {
 203                 host = NULL;
 204                 nsm = nsm_find(ni->sap, ni->salen,
 205                                 ni->hostname, ni->hostname_len, 1);
 206                 if (!nsm) {
 207                         dprintk("lockd: nlm_lookup_host failed; "
 208                                 "no nsm handle\n");
 209                         goto out;
 210                 }
 211         }
 212
 213         host = kzalloc(sizeof(*host), GFP_KERNEL);
 214         if (!host) {
 215                 nsm_release(nsm);
 216                 dprintk("lockd: nlm_lookup_host failed; no memory\n");
 217                 goto out;
 218         }
 219         host->h_name       = nsm->sm_name;
 220         host->h_addrbuf    = nsm->sm_addrbuf;
 221         memcpy(nlm_addr(host), ni->sap, ni->salen);
 222         host->h_addrlen = ni->salen;
 223         nlm_clear_port(nlm_addr(host));
 224         memcpy(nlm_srcaddr(host), ni->src_sap, ni->src_len);
 225         host->h_version    = ni->version;
 226         host->h_proto      = ni->protocol;
 227         host->h_rpcclnt    = NULL;
 228         mutex_init(&host->h_mutex);
 229         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 230         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 231         atomic_set(&host->h_count, 1);
 232         init_waitqueue_head(&host->h_gracewait);
 233         init_rwsem(&host->h_rwsem);
 234         host->h_state      = 0;                 /* pseudo NSM state */
 235         host->h_nsmstate   = 0;                 /* real NSM state */
 236         host->h_nsmhandle  = nsm;
 237         host->h_server     = ni->server;
 238         host->h_noresvport = ni->noresvport;
 239         hlist_add_head(&host->h_hash, chain);
 240         INIT_LIST_HEAD(&host->h_lockowners);
 241         spin_lock_init(&host->h_lock);
 242         INIT_LIST_HEAD(&host->h_granted);
 243         INIT_LIST_HEAD(&host->h_reclaim);
 244
 245         nrhosts++;
 246
 247         dprintk("lockd: nlm_lookup_host created host %s\n",
 248                         host->h_name);
 249
 250 out:
 251         mutex_unlock(&nlm_host_mutex);
 252         return host;
 253 }
 254
 255 /*
 256  * Destroy a host
 257  */
 258 static void
 259 nlm_destroy_host(struct nlm_host *host)
 260 {
 261         struct rpc_clnt *clnt;
 262
 263         BUG_ON(!list_empty(&host->h_lockowners));
 264         BUG_ON(atomic_read(&host->h_count));
 265
 266         /*
 267          * Release NSM handle and unmonitor host.
 268          */
 269         nsm_unmonitor(host);
 270
 271         clnt = host->h_rpcclnt;
 272         if (clnt != NULL)
 273                 rpc_shutdown_client(clnt);
 274         kfree(host);
 275 }
 276
 277 /**
 278  * nlmclnt_lookup_host - Find an NLM host handle matching a remote server
 279  * @sap: network address of server
 280  * @salen: length of server address
 281  * @protocol: transport protocol to use
 282  * @version: NLM protocol version
 283  * @hostname: '\0'-terminated hostname of server
 284  * @noresvport: 1 if non-privileged port should be used
 285  *
 286  * Returns an nlm_host structure that matches the passed-in
 287  * [server address, transport protocol, NLM version, server hostname].
 288  * If one doesn't already exist in the host cache, a new handle is
 289  * created and returned.
 290  */
 291 struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap,
 292                                      const size_t salen,
 293                                      const unsigned short protocol,
 294                                      const u32 version,
 295                                      const char *hostname,
 296                                      int noresvport)
 297 {
 298         const struct sockaddr source = {
 299                 .sa_family      = AF_UNSPEC,
 300         };
 301         struct nlm_lookup_host_info ni = {
 302                 .server         = 0,
 303                 .sap            = sap,
 304                 .salen          = salen,
 305                 .protocol       = protocol,
 306                 .version        = version,
 307                 .hostname       = hostname,
 308                 .hostname_len   = strlen(hostname),
 309                 .src_sap        = &source,
 310                 .src_len        = sizeof(source),
 311                 .noresvport     = noresvport,
 312         };
 313
 314         dprintk("lockd: %s(host='%s', vers=%u, proto=%s)\n", __func__,
 315                         (hostname ? hostname : "<none>"), version,
 316                         (protocol == IPPROTO_UDP ? "udp" : "tcp"));
 317
 318         return nlm_lookup_host(&ni);
 319 }
 320
 321 /**
 322  * nlmsvc_lookup_host - Find an NLM host handle matching a remote client
 323  * @rqstp: incoming NLM request
 324  * @hostname: name of client host
 325  * @hostname_len: length of client hostname
 326  *
 327  * Returns an nlm_host structure that matches the [client address,
 328  * transport protocol, NLM version, client hostname] of the passed-in
 329  * NLM request.  If one doesn't already exist in the host cache, a
 330  * new handle is created and returned.
 331  *
 332  * Before possibly creating a new nlm_host, construct a sockaddr
 333  * for a specific source address in case the local system has
 334  * multiple network addresses.  The family of the address in
 335  * rq_daddr is guaranteed to be the same as the family of the
 336  * address in rq_addr, so it's safe to use the same family for
 337  * the source address.
 338  */
 339 struct nlm_host *nlmsvc_lookup_host(const struct svc_rqst *rqstp,
 340                                     const char *hostname,
 341                                     const size_t hostname_len)
 342 {
 343         struct sockaddr_in sin = {
 344                 .sin_family     = AF_INET,
 345         };
 346         struct sockaddr_in6 sin6 = {
 347                 .sin6_family    = AF_INET6,
 348         };
 349         struct nlm_lookup_host_info ni = {
 350                 .server         = 1,
 351                 .sap            = svc_addr(rqstp),
 352                 .salen          = rqstp->rq_addrlen,
 353                 .protocol       = rqstp->rq_prot,
 354                 .version        = rqstp->rq_vers,
 355                 .hostname       = hostname,
 356                 .hostname_len   = hostname_len,
 357                 .src_len        = rqstp->rq_addrlen,
 358         };
 359
 360         dprintk("lockd: %s(host='%*s', vers=%u, proto=%s)\n", __func__,
 361                         (int)hostname_len, hostname, rqstp->rq_vers,
 362                         (rqstp->rq_prot == IPPROTO_UDP ? "udp" : "tcp"));
 363
 364         switch (ni.sap->sa_family) {
 365         case AF_INET:
 366                 sin.sin_addr.s_addr = rqstp->rq_daddr.addr.s_addr;
 367                 ni.src_sap = (struct sockaddr *)&sin;
 368                 break;
 369         case AF_INET6:
 370                 ipv6_addr_copy(&sin6.sin6_addr, &rqstp->rq_daddr.addr6);
 371                 ni.src_sap = (struct sockaddr *)&sin6;
 372                 break;
 373         default:
 374                 return NULL;
 375         }
 376
 377         return nlm_lookup_host(&ni);
 378 }
 379
 380 /*
 381  * Create the NLM RPC client for an NLM peer
 382  */
 383 struct rpc_clnt *
 384 nlm_bind_host(struct nlm_host *host)
 385 {
 386         struct rpc_clnt *clnt;
 387
 388         dprintk("lockd: nlm_bind_host %s (%s)\n",
 389                         host->h_name, host->h_addrbuf);
 390
 391         /* Lock host handle */
 392         mutex_lock(&host->h_mutex);
 393
 394         /* If we've already created an RPC client, check whether
 395          * RPC rebind is required
 396          */
 397         if ((clnt = host->h_rpcclnt) != NULL) {
 398                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 399                         rpc_force_rebind(clnt);
 400                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 401                         dprintk("lockd: next rebind in %lu jiffies\n",
 402                                         host->h_nextrebind - jiffies);
 403                 }
 404         } else {
 405                 unsigned long increment = nlmsvc_timeout;
 406                 struct rpc_timeout timeparms = {
 407                         .to_initval     = increment,
 408                         .to_increment   = increment,
 409                         .to_maxval      = increment * 6UL,
 410                         .to_retries     = 5U,
 411                 };
 412                 struct rpc_create_args args = {
 413                         .protocol       = host->h_proto,
 414                         .address        = nlm_addr(host),
 415                         .addrsize       = host->h_addrlen,
 416                         .saddress       = nlm_srcaddr(host),
 417                         .timeout        = &timeparms,
 418                         .servername     = host->h_name,
 419                         .program        = &nlm_program,
 420                         .version        = host->h_version,
 421                         .authflavor     = RPC_AUTH_UNIX,
 422                         .flags          = (RPC_CLNT_CREATE_NOPING |
 423                                            RPC_CLNT_CREATE_AUTOBIND),
 424                 };
 425
 426                 /*
 427                  * lockd retries server side blocks automatically so we want
 428                  * those to be soft RPC calls. Client side calls need to be
 429                  * hard RPC tasks.
 430                  */
 431                 if (!host->h_server)
 432                         args.flags |= RPC_CLNT_CREATE_HARDRTRY;
 433                 if (host->h_noresvport)
 434                         args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
 435
 436                 clnt = rpc_create(&args);
 437                 if (!IS_ERR(clnt))
 438                         host->h_rpcclnt = clnt;
 439                 else {
 440                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 441                         clnt = NULL;
 442                 }
 443         }
 444
 445         mutex_unlock(&host->h_mutex);
 446         return clnt;
 447 }
 448
 449 /*
 450  * Force a portmap lookup of the remote lockd port
 451  */
 452 void
 453 nlm_rebind_host(struct nlm_host *host)
 454 {
 455         dprintk("lockd: rebind host %s\n", host->h_name);
 456         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 457                 rpc_force_rebind(host->h_rpcclnt);
 458                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 459         }
 460 }
 461
 462 /*
 463  * Increment NLM host count
 464  */
 465 struct nlm_host * nlm_get_host(struct nlm_host *host)
 466 {
 467         if (host) {
 468                 dprintk("lockd: get host %s\n", host->h_name);
 469                 atomic_inc(&host->h_count);
 470                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 471         }
 472         return host;
 473 }
 474
 475 /*
 476  * Release NLM host after use
 477  */
 478 void nlm_release_host(struct nlm_host *host)
 479 {
 480         if (host != NULL) {
 481                 dprintk("lockd: release host %s\n", host->h_name);
 482                 BUG_ON(atomic_read(&host->h_count) < 0);
 483                 if (atomic_dec_and_test(&host->h_count)) {
 484                         BUG_ON(!list_empty(&host->h_lockowners));
 485                         BUG_ON(!list_empty(&host->h_granted));
 486                         BUG_ON(!list_empty(&host->h_reclaim));
 487                 }
 488         }
 489 }
 490
 491 /*
 492  * We were notified that the host indicated by address &sin
 493  * has rebooted.
 494  * Release all resources held by that peer.
 495  */
 496 void nlm_host_rebooted(const struct sockaddr_in *sin,
 497                                 const char *hostname,
 498                                 unsigned int hostname_len,
 499                                 u32 new_state)
 500 {
 501         struct hlist_head *chain;
 502         struct hlist_node *pos;
 503         struct nsm_handle *nsm;
 504         struct nlm_host *host;
 505
 506         nsm = nsm_find((struct sockaddr *)sin, sizeof(*sin),
 507                         hostname, hostname_len, 0);
 508         if (nsm == NULL) {
 509                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
 510                                 hostname_len, hostname);
 511                 return;
 512         }
 513
 514         dprintk("lockd: nlm_host_rebooted(%.*s, %s)\n",
 515                         hostname_len, hostname, nsm->sm_addrbuf);
 516
 517         /* When reclaiming locks on this peer, make sure that
 518          * we set up a new notification */
 519         nsm->sm_monitored = 0;
 520
 521         /* Mark all hosts tied to this NSM state as having rebooted.
 522          * We run the loop repeatedly, because we drop the host table
 523          * lock for this.
 524          * To avoid processing a host several times, we match the nsmstate.
 525          */
 526 again:  mutex_lock(&nlm_host_mutex);
 527         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 528                 hlist_for_each_entry(host, pos, chain, h_hash) {
 529                         if (host->h_nsmhandle == nsm
 530                          && host->h_nsmstate != new_state) {
 531                                 host->h_nsmstate = new_state;
 532                                 host->h_state++;
 533
 534                                 nlm_get_host(host);
 535                                 mutex_unlock(&nlm_host_mutex);
 536
 537                                 if (host->h_server) {
 538                                         /* We're server for this guy, just ditch
 539                                          * all the locks he held. */
 540                                         nlmsvc_free_host_resources(host);
 541                                 } else {
 542                                         /* He's the server, initiate lock recovery. */
 543                                         nlmclnt_recovery(host);
 544                                 }
 545
 546                                 nlm_release_host(host);
 547                                 goto again;
 548                         }
 549                 }
 550         }
 551
 552         mutex_unlock(&nlm_host_mutex);
 553 }
 554
 555 /*
 556  * Shut down the hosts module.
 557  * Note that this routine is called only at server shutdown time.
 558  */
 559 void
 560 nlm_shutdown_hosts(void)
 561 {
 562         struct hlist_head *chain;
 563         struct hlist_node *pos;
 564         struct nlm_host *host;
 565
 566         dprintk("lockd: shutting down host module\n");
 567         mutex_lock(&nlm_host_mutex);
 568
 569         /* First, make all hosts eligible for gc */
 570         dprintk("lockd: nuking all hosts...\n");
 571         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 572                 hlist_for_each_entry(host, pos, chain, h_hash) {
 573                         host->h_expires = jiffies - 1;
 574                         if (host->h_rpcclnt) {
 575                                 rpc_shutdown_client(host->h_rpcclnt);
 576                                 host->h_rpcclnt = NULL;
 577                         }
 578                 }
 579         }
 580
 581         /* Then, perform a garbage collection pass */
 582         nlm_gc_hosts();
 583         mutex_unlock(&nlm_host_mutex);
 584
 585         /* complain if any hosts are left */
 586         if (nrhosts) {
 587                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 588                 dprintk("lockd: %d hosts left:\n", nrhosts);
 589                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 590                         hlist_for_each_entry(host, pos, chain, h_hash) {
 591                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 592                                         host->h_name, atomic_read(&host->h_count),
 593                                         host->h_inuse, host->h_expires);
 594                         }
 595                 }
 596         }
 597 }
 598
 599 /*
 600  * Garbage collect any unused NLM hosts.
 601  * This GC combines reference counting for async operations with
 602  * mark & sweep for resources held by remote clients.
 603  */
 604 static void
 605 nlm_gc_hosts(void)
 606 {
 607         struct hlist_head *chain;
 608         struct hlist_node *pos, *next;
 609         struct nlm_host *host;
 610
 611         dprintk("lockd: host garbage collection\n");
 612         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 613                 hlist_for_each_entry(host, pos, chain, h_hash)
 614                         host->h_inuse = 0;
 615         }
 616
 617         /* Mark all hosts that hold locks, blocks or shares */
 618         nlmsvc_mark_resources();
 619
 620         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 621                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 622                         if (atomic_read(&host->h_count) || host->h_inuse
 623                          || time_before(jiffies, host->h_expires)) {
 624                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 625                                         host->h_name, atomic_read(&host->h_count),
 626                                         host->h_inuse, host->h_expires);
 627                                 continue;
 628                         }
 629                         dprintk("lockd: delete host %s\n", host->h_name);
 630                         hlist_del_init(&host->h_hash);
 631
 632                         nlm_destroy_host(host);
 633                         nrhosts--;
 634                 }
 635         }
 636
 637         next_gc = jiffies + NLM_HOST_COLLECT;
 638 }
 639
 640
 641 /*
 642  * Manage NSM handles
 643  */
 644 static LIST_HEAD(nsm_handles);
 645 static DEFINE_SPINLOCK(nsm_lock);
 646
 647 static struct nsm_handle *nsm_find(const struct sockaddr *sap,
 648                                    const size_t salen,
 649                                    const char *hostname,
 650                                    const size_t hostname_len,
 651                                    const int create)
 652 {
 653         struct nsm_handle *nsm = NULL;
 654         struct nsm_handle *pos;
 655
 656         if (!sap)
 657                 return NULL;
 658
 659         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 660                 if (printk_ratelimit()) {
 661                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 662                                             "in NFS lock request\n",
 663                                 (int)hostname_len, hostname);
 664                 }
 665                 return NULL;
 666         }
 667
 668 retry:
 669         spin_lock(&nsm_lock);
 670         list_for_each_entry(pos, &nsm_handles, sm_link) {
 671
 672                 if (hostname && nsm_use_hostnames) {
 673                         if (strlen(pos->sm_name) != hostname_len
 674                          || memcmp(pos->sm_name, hostname, hostname_len))
 675                                 continue;
 676                 } else if (!nlm_cmp_addr(nsm_addr(pos), sap))
 677                         continue;
 678                 atomic_inc(&pos->sm_count);
 679                 kfree(nsm);
 680                 nsm = pos;
 681                 goto found;
 682         }
 683         if (nsm) {
 684                 list_add(&nsm->sm_link, &nsm_handles);
 685                 goto found;
 686         }
 687         spin_unlock(&nsm_lock);
 688
 689         if (!create)
 690                 return NULL;
 691
 692         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 693         if (nsm == NULL)
 694                 return NULL;
 695
 696         memcpy(nsm_addr(nsm), sap, salen);
 697         nsm->sm_addrlen = salen;
 698         nsm->sm_name = (char *) (nsm + 1);
 699         memcpy(nsm->sm_name, hostname, hostname_len);
 700         nsm->sm_name[hostname_len] = '\0';
 701         nlm_display_address((struct sockaddr *)&nsm->sm_addr,
 702                                 nsm->sm_addrbuf, sizeof(nsm->sm_addrbuf));
 703         atomic_set(&nsm->sm_count, 1);
 704         goto retry;
 705
 706 found:
 707         spin_unlock(&nsm_lock);
 708         return nsm;
 709 }
 710
 711 /*
 712  * Release an NSM handle
 713  */
 714 void
 715 nsm_release(struct nsm_handle *nsm)
 716 {
 717         if (!nsm)
 718                 return;
 719         if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
 720                 list_del(&nsm->sm_link);
 721                 spin_unlock(&nsm_lock);
 722                 kfree(nsm);
 723         }
 724 }