fs/lockd/host.c

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