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