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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_ipv6_address(const struct sockaddr *sap, char *buf,
 109                                      const size_t len)
 110 {
 111         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
 112
 113         if (ipv6_addr_v4mapped(&sin6->sin6_addr))
 114                 snprintf(buf, len, "%pI4", &sin6->sin6_addr.s6_addr32[3]);
 115         else if (sin6->sin6_scope_id != 0)
 116                 snprintf(buf, len, "%pI6%%%u", &sin6->sin6_addr,
 117                                 sin6->sin6_scope_id);
 118         else
 119                 snprintf(buf, len, "%pI6", &sin6->sin6_addr);
 120 }
 121
 122 static void nlm_display_address(const struct sockaddr *sap,
 123                                 char *buf, const size_t len)
 124 {
 125         const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
 126
 127         switch (sap->sa_family) {
 128         case AF_INET:
 129                 snprintf(buf, len, "%pI4", &sin->sin_addr.s_addr);
 130                 break;
 131         case AF_INET6:
 132                 nlm_display_ipv6_address(sap, buf, len);
 133                 break;
 134         default:
 135                 snprintf(buf, len, "unsupported address family");
 136                 break;
 137         }
 138 }
 139
 140 /*
 141  * Common host lookup routine for server & client
 142  */
 143 static struct nlm_host *nlm_lookup_host(struct nlm_lookup_host_info *ni)
 144 {
 145         struct hlist_head *chain;
 146         struct hlist_node *pos;
 147         struct nlm_host *host;
 148         struct nsm_handle *nsm = NULL;
 149
 150         mutex_lock(&nlm_host_mutex);
 151
 152         if (time_after_eq(jiffies, next_gc))
 153                 nlm_gc_hosts();
 154
 155         /* We may keep several nlm_host objects for a peer, because each
 156          * nlm_host is identified by
 157          * (address, protocol, version, server/client)
 158          * We could probably simplify this a little by putting all those
 159          * different NLM rpc_clients into one single nlm_host object.
 160          * This would allow us to have one nlm_host per address.
 161          */
 162         chain = &nlm_hosts[nlm_hash_address(ni->sap)];
 163         hlist_for_each_entry(host, pos, chain, h_hash) {
 164                 if (!nlm_cmp_addr(nlm_addr(host), ni->sap))
 165                         continue;
 166
 167                 /* See if we have an NSM handle for this client */
 168                 if (!nsm)
 169                         nsm = host->h_nsmhandle;
 170
 171                 if (host->h_proto != ni->protocol)
 172                         continue;
 173                 if (host->h_version != ni->version)
 174                         continue;
 175                 if (host->h_server != ni->server)
 176                         continue;
 177                 if (ni->server &&
 178                     !nlm_cmp_addr(nlm_srcaddr(host), ni->src_sap))
 179                         continue;
 180
 181                 /* Move to head of hash chain. */
 182                 hlist_del(&host->h_hash);
 183                 hlist_add_head(&host->h_hash, chain);
 184
 185                 nlm_get_host(host);
 186                 dprintk("lockd: nlm_lookup_host found host %s (%s)\n",
 187                                 host->h_name, host->h_addrbuf);
 188                 goto out;
 189         }
 190
 191         /*
 192          * The host wasn't in our hash table.  If we don't
 193          * have an NSM handle for it yet, create one.
 194          */
 195         if (nsm)
 196                 atomic_inc(&nsm->sm_count);
 197         else {
 198                 host = NULL;
 199                 nsm = nsm_find(ni->sap, ni->salen,
 200                                 ni->hostname, ni->hostname_len, 1);
 201                 if (!nsm) {
 202                         dprintk("lockd: nlm_lookup_host failed; "
 203                                 "no nsm handle\n");
 204                         goto out;
 205                 }
 206         }
 207
 208         host = kzalloc(sizeof(*host), GFP_KERNEL);
 209         if (!host) {
 210                 nsm_release(nsm);
 211                 dprintk("lockd: nlm_lookup_host failed; no memory\n");
 212                 goto out;
 213         }
 214         host->h_name       = nsm->sm_name;
 215         host->h_addrbuf    = nsm->sm_addrbuf;
 216         memcpy(nlm_addr(host), ni->sap, ni->salen);
 217         host->h_addrlen = ni->salen;
 218         nlm_clear_port(nlm_addr(host));
 219         memcpy(nlm_srcaddr(host), ni->src_sap, ni->src_len);
 220         host->h_version    = ni->version;
 221         host->h_proto      = ni->protocol;
 222         host->h_rpcclnt    = NULL;
 223         mutex_init(&host->h_mutex);
 224         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 225         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 226         atomic_set(&host->h_count, 1);
 227         init_waitqueue_head(&host->h_gracewait);
 228         init_rwsem(&host->h_rwsem);
 229         host->h_state      = 0;                 /* pseudo NSM state */
 230         host->h_nsmstate   = 0;                 /* real NSM state */
 231         host->h_nsmhandle  = nsm;
 232         host->h_server     = ni->server;
 233         host->h_noresvport = ni->noresvport;
 234         hlist_add_head(&host->h_hash, chain);
 235         INIT_LIST_HEAD(&host->h_lockowners);
 236         spin_lock_init(&host->h_lock);
 237         INIT_LIST_HEAD(&host->h_granted);
 238         INIT_LIST_HEAD(&host->h_reclaim);
 239
 240         nrhosts++;
 241
 242         dprintk("lockd: nlm_lookup_host created host %s\n",
 243                         host->h_name);
 244
 245 out:
 246         mutex_unlock(&nlm_host_mutex);
 247         return host;
 248 }
 249
 250 /*
 251  * Destroy a host
 252  */
 253 static void
 254 nlm_destroy_host(struct nlm_host *host)
 255 {
 256         struct rpc_clnt *clnt;
 257
 258         BUG_ON(!list_empty(&host->h_lockowners));
 259         BUG_ON(atomic_read(&host->h_count));
 260
 261         /*
 262          * Release NSM handle and unmonitor host.
 263          */
 264         nsm_unmonitor(host);
 265
 266         clnt = host->h_rpcclnt;
 267         if (clnt != NULL)
 268                 rpc_shutdown_client(clnt);
 269         kfree(host);
 270 }
 271
 272 /**
 273  * nlmclnt_lookup_host - Find an NLM host handle matching a remote server
 274  * @sap: network address of server
 275  * @salen: length of server address
 276  * @protocol: transport protocol to use
 277  * @version: NLM protocol version
 278  * @hostname: '\0'-terminated hostname of server
 279  * @noresvport: 1 if non-privileged port should be used
 280  *
 281  * Returns an nlm_host structure that matches the passed-in
 282  * [server address, transport protocol, NLM version, server hostname].
 283  * If one doesn't already exist in the host cache, a new handle is
 284  * created and returned.
 285  */
 286 struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap,
 287                                      const size_t salen,
 288                                      const unsigned short protocol,
 289                                      const u32 version,
 290                                      const char *hostname,
 291                                      int noresvport)
 292 {
 293         const struct sockaddr source = {
 294                 .sa_family      = AF_UNSPEC,
 295         };
 296         struct nlm_lookup_host_info ni = {
 297                 .server         = 0,
 298                 .sap            = sap,
 299                 .salen          = salen,
 300                 .protocol       = protocol,
 301                 .version        = version,
 302                 .hostname       = hostname,
 303                 .hostname_len   = strlen(hostname),
 304                 .src_sap        = &source,
 305                 .src_len        = sizeof(source),
 306                 .noresvport     = noresvport,
 307         };
 308
 309         dprintk("lockd: %s(host='%s', vers=%u, proto=%s)\n", __func__,
 310                         (hostname ? hostname : "<none>"), version,
 311                         (protocol == IPPROTO_UDP ? "udp" : "tcp"));
 312
 313         return nlm_lookup_host(&ni);
 314 }
 315
 316 /**
 317  * nlmsvc_lookup_host - Find an NLM host handle matching a remote client
 318  * @rqstp: incoming NLM request
 319  * @hostname: name of client host
 320  * @hostname_len: length of client hostname
 321  *
 322  * Returns an nlm_host structure that matches the [client address,
 323  * transport protocol, NLM version, client hostname] of the passed-in
 324  * NLM request.  If one doesn't already exist in the host cache, a
 325  * new handle is created and returned.
 326  *
 327  * Before possibly creating a new nlm_host, construct a sockaddr
 328  * for a specific source address in case the local system has
 329  * multiple network addresses.  The family of the address in
 330  * rq_daddr is guaranteed to be the same as the family of the
 331  * address in rq_addr, so it's safe to use the same family for
 332  * the source address.
 333  */
 334 struct nlm_host *nlmsvc_lookup_host(const struct svc_rqst *rqstp,
 335                                     const char *hostname,
 336                                     const size_t hostname_len)
 337 {
 338         struct sockaddr_in sin = {
 339                 .sin_family     = AF_INET,
 340         };
 341         struct sockaddr_in6 sin6 = {
 342                 .sin6_family    = AF_INET6,
 343         };
 344         struct nlm_lookup_host_info ni = {
 345                 .server         = 1,
 346                 .sap            = svc_addr(rqstp),
 347                 .salen          = rqstp->rq_addrlen,
 348                 .protocol       = rqstp->rq_prot,
 349                 .version        = rqstp->rq_vers,
 350                 .hostname       = hostname,
 351                 .hostname_len   = hostname_len,
 352                 .src_len        = rqstp->rq_addrlen,
 353         };
 354
 355         dprintk("lockd: %s(host='%*s', vers=%u, proto=%s)\n", __func__,
 356                         (int)hostname_len, hostname, rqstp->rq_vers,
 357                         (rqstp->rq_prot == IPPROTO_UDP ? "udp" : "tcp"));
 358
 359         switch (ni.sap->sa_family) {
 360         case AF_INET:
 361                 sin.sin_addr.s_addr = rqstp->rq_daddr.addr.s_addr;
 362                 ni.src_sap = (struct sockaddr *)&sin;
 363                 break;
 364         case AF_INET6:
 365                 ipv6_addr_copy(&sin6.sin6_addr, &rqstp->rq_daddr.addr6);
 366                 ni.src_sap = (struct sockaddr *)&sin6;
 367                 break;
 368         default:
 369                 return NULL;
 370         }
 371
 372         return nlm_lookup_host(&ni);
 373 }
 374
 375 /*
 376  * Create the NLM RPC client for an NLM peer
 377  */
 378 struct rpc_clnt *
 379 nlm_bind_host(struct nlm_host *host)
 380 {
 381         struct rpc_clnt *clnt;
 382
 383         dprintk("lockd: nlm_bind_host %s (%s)\n",
 384                         host->h_name, host->h_addrbuf);
 385
 386         /* Lock host handle */
 387         mutex_lock(&host->h_mutex);
 388
 389         /* If we've already created an RPC client, check whether
 390          * RPC rebind is required
 391          */
 392         if ((clnt = host->h_rpcclnt) != NULL) {
 393                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 394                         rpc_force_rebind(clnt);
 395                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 396                         dprintk("lockd: next rebind in %lu jiffies\n",
 397                                         host->h_nextrebind - jiffies);
 398                 }
 399         } else {
 400                 unsigned long increment = nlmsvc_timeout;
 401                 struct rpc_timeout timeparms = {
 402                         .to_initval     = increment,
 403                         .to_increment   = increment,
 404                         .to_maxval      = increment * 6UL,
 405                         .to_retries     = 5U,
 406                 };
 407                 struct rpc_create_args args = {
 408                         .protocol       = host->h_proto,
 409                         .address        = nlm_addr(host),
 410                         .addrsize       = host->h_addrlen,
 411                         .saddress       = nlm_srcaddr(host),
 412                         .timeout        = &timeparms,
 413                         .servername     = host->h_name,
 414                         .program        = &nlm_program,
 415                         .version        = host->h_version,
 416                         .authflavor     = RPC_AUTH_UNIX,
 417                         .flags          = (RPC_CLNT_CREATE_NOPING |
 418                                            RPC_CLNT_CREATE_AUTOBIND),
 419                 };
 420
 421                 /*
 422                  * lockd retries server side blocks automatically so we want
 423                  * those to be soft RPC calls. Client side calls need to be
 424                  * hard RPC tasks.
 425                  */
 426                 if (!host->h_server)
 427                         args.flags |= RPC_CLNT_CREATE_HARDRTRY;
 428                 if (host->h_noresvport)
 429                         args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
 430
 431                 clnt = rpc_create(&args);
 432                 if (!IS_ERR(clnt))
 433                         host->h_rpcclnt = clnt;
 434                 else {
 435                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 436                         clnt = NULL;
 437                 }
 438         }
 439
 440         mutex_unlock(&host->h_mutex);
 441         return clnt;
 442 }
 443
 444 /*
 445  * Force a portmap lookup of the remote lockd port
 446  */
 447 void
 448 nlm_rebind_host(struct nlm_host *host)
 449 {
 450         dprintk("lockd: rebind host %s\n", host->h_name);
 451         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 452                 rpc_force_rebind(host->h_rpcclnt);
 453                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 454         }
 455 }
 456
 457 /*
 458  * Increment NLM host count
 459  */
 460 struct nlm_host * nlm_get_host(struct nlm_host *host)
 461 {
 462         if (host) {
 463                 dprintk("lockd: get host %s\n", host->h_name);
 464                 atomic_inc(&host->h_count);
 465                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 466         }
 467         return host;
 468 }
 469
 470 /*
 471  * Release NLM host after use
 472  */
 473 void nlm_release_host(struct nlm_host *host)
 474 {
 475         if (host != NULL) {
 476                 dprintk("lockd: release host %s\n", host->h_name);
 477                 BUG_ON(atomic_read(&host->h_count) < 0);
 478                 if (atomic_dec_and_test(&host->h_count)) {
 479                         BUG_ON(!list_empty(&host->h_lockowners));
 480                         BUG_ON(!list_empty(&host->h_granted));
 481                         BUG_ON(!list_empty(&host->h_reclaim));
 482                 }
 483         }
 484 }
 485
 486 /*
 487  * We were notified that the host indicated by address &sin
 488  * has rebooted.
 489  * Release all resources held by that peer.
 490  */
 491 void nlm_host_rebooted(const struct sockaddr_in *sin,
 492                                 const char *hostname,
 493                                 unsigned int hostname_len,
 494                                 u32 new_state)
 495 {
 496         struct hlist_head *chain;
 497         struct hlist_node *pos;
 498         struct nsm_handle *nsm;
 499         struct nlm_host *host;
 500
 501         nsm = nsm_find((struct sockaddr *)sin, sizeof(*sin),
 502                         hostname, hostname_len, 0);
 503         if (nsm == NULL) {
 504                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
 505                                 hostname_len, hostname);
 506                 return;
 507         }
 508
 509         dprintk("lockd: nlm_host_rebooted(%.*s, %s)\n",
 510                         hostname_len, hostname, nsm->sm_addrbuf);
 511
 512         /* When reclaiming locks on this peer, make sure that
 513          * we set up a new notification */
 514         nsm->sm_monitored = 0;
 515
 516         /* Mark all hosts tied to this NSM state as having rebooted.
 517          * We run the loop repeatedly, because we drop the host table
 518          * lock for this.
 519          * To avoid processing a host several times, we match the nsmstate.
 520          */
 521 again:  mutex_lock(&nlm_host_mutex);
 522         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 523                 hlist_for_each_entry(host, pos, chain, h_hash) {
 524                         if (host->h_nsmhandle == nsm
 525                          && host->h_nsmstate != new_state) {
 526                                 host->h_nsmstate = new_state;
 527                                 host->h_state++;
 528
 529                                 nlm_get_host(host);
 530                                 mutex_unlock(&nlm_host_mutex);
 531
 532                                 if (host->h_server) {
 533                                         /* We're server for this guy, just ditch
 534                                          * all the locks he held. */
 535                                         nlmsvc_free_host_resources(host);
 536                                 } else {
 537                                         /* He's the server, initiate lock recovery. */
 538                                         nlmclnt_recovery(host);
 539                                 }
 540
 541                                 nlm_release_host(host);
 542                                 goto again;
 543                         }
 544                 }
 545         }
 546
 547         mutex_unlock(&nlm_host_mutex);
 548 }
 549
 550 /*
 551  * Shut down the hosts module.
 552  * Note that this routine is called only at server shutdown time.
 553  */
 554 void
 555 nlm_shutdown_hosts(void)
 556 {
 557         struct hlist_head *chain;
 558         struct hlist_node *pos;
 559         struct nlm_host *host;
 560
 561         dprintk("lockd: shutting down host module\n");
 562         mutex_lock(&nlm_host_mutex);
 563
 564         /* First, make all hosts eligible for gc */
 565         dprintk("lockd: nuking all hosts...\n");
 566         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 567                 hlist_for_each_entry(host, pos, chain, h_hash) {
 568                         host->h_expires = jiffies - 1;
 569                         if (host->h_rpcclnt) {
 570                                 rpc_shutdown_client(host->h_rpcclnt);
 571                                 host->h_rpcclnt = NULL;
 572                         }
 573                 }
 574         }
 575
 576         /* Then, perform a garbage collection pass */
 577         nlm_gc_hosts();
 578         mutex_unlock(&nlm_host_mutex);
 579
 580         /* complain if any hosts are left */
 581         if (nrhosts) {
 582                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 583                 dprintk("lockd: %d hosts left:\n", nrhosts);
 584                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 585                         hlist_for_each_entry(host, pos, chain, h_hash) {
 586                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 587                                         host->h_name, atomic_read(&host->h_count),
 588                                         host->h_inuse, host->h_expires);
 589                         }
 590                 }
 591         }
 592 }
 593
 594 /*
 595  * Garbage collect any unused NLM hosts.
 596  * This GC combines reference counting for async operations with
 597  * mark & sweep for resources held by remote clients.
 598  */
 599 static void
 600 nlm_gc_hosts(void)
 601 {
 602         struct hlist_head *chain;
 603         struct hlist_node *pos, *next;
 604         struct nlm_host *host;
 605
 606         dprintk("lockd: host garbage collection\n");
 607         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 608                 hlist_for_each_entry(host, pos, chain, h_hash)
 609                         host->h_inuse = 0;
 610         }
 611
 612         /* Mark all hosts that hold locks, blocks or shares */
 613         nlmsvc_mark_resources();
 614
 615         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 616                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 617                         if (atomic_read(&host->h_count) || host->h_inuse
 618                          || time_before(jiffies, host->h_expires)) {
 619                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 620                                         host->h_name, atomic_read(&host->h_count),
 621                                         host->h_inuse, host->h_expires);
 622                                 continue;
 623                         }
 624                         dprintk("lockd: delete host %s\n", host->h_name);
 625                         hlist_del_init(&host->h_hash);
 626
 627                         nlm_destroy_host(host);
 628                         nrhosts--;
 629                 }
 630         }
 631
 632         next_gc = jiffies + NLM_HOST_COLLECT;
 633 }
 634
 635
 636 /*
 637  * Manage NSM handles
 638  */
 639 static LIST_HEAD(nsm_handles);
 640 static DEFINE_SPINLOCK(nsm_lock);
 641
 642 static struct nsm_handle *nsm_find(const struct sockaddr *sap,
 643                                    const size_t salen,
 644                                    const char *hostname,
 645                                    const size_t hostname_len,
 646                                    const int create)
 647 {
 648         struct nsm_handle *nsm = NULL;
 649         struct nsm_handle *pos;
 650
 651         if (!sap)
 652                 return NULL;
 653
 654         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 655                 if (printk_ratelimit()) {
 656                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 657                                             "in NFS lock request\n",
 658                                 (int)hostname_len, hostname);
 659                 }
 660                 return NULL;
 661         }
 662
 663 retry:
 664         spin_lock(&nsm_lock);
 665         list_for_each_entry(pos, &nsm_handles, sm_link) {
 666
 667                 if (hostname && nsm_use_hostnames) {
 668                         if (strlen(pos->sm_name) != hostname_len
 669                          || memcmp(pos->sm_name, hostname, hostname_len))
 670                                 continue;
 671                 } else if (!nlm_cmp_addr(nsm_addr(pos), sap))
 672                         continue;
 673                 atomic_inc(&pos->sm_count);
 674                 kfree(nsm);
 675                 nsm = pos;
 676                 goto found;
 677         }
 678         if (nsm) {
 679                 list_add(&nsm->sm_link, &nsm_handles);
 680                 goto found;
 681         }
 682         spin_unlock(&nsm_lock);
 683
 684         if (!create)
 685                 return NULL;
 686
 687         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 688         if (nsm == NULL)
 689                 return NULL;
 690
 691         memcpy(nsm_addr(nsm), sap, salen);
 692         nsm->sm_addrlen = salen;
 693         nsm->sm_name = (char *) (nsm + 1);
 694         memcpy(nsm->sm_name, hostname, hostname_len);
 695         nsm->sm_name[hostname_len] = '\0';
 696         nlm_display_address((struct sockaddr *)&nsm->sm_addr,
 697                                 nsm->sm_addrbuf, sizeof(nsm->sm_addrbuf));
 698         atomic_set(&nsm->sm_count, 1);
 699         goto retry;
 700
 701 found:
 702         spin_unlock(&nsm_lock);
 703         return nsm;
 704 }
 705
 706 /*
 707  * Release an NSM handle
 708  */
 709 void
 710 nsm_release(struct nsm_handle *nsm)
 711 {
 712         if (!nsm)
 713                 return;
 714         if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
 715                 list_del(&nsm->sm_link);
 716                 spin_unlock(&nsm_lock);
 717                 kfree(nsm);
 718         }
 719 }