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