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, pos, chain, table) \
  36         for ((chain) = (table); \
  37              (chain) < (table) + NLM_HOST_NRHASH; ++(chain)) \
  38                 hlist_for_each_entry((host), (pos), (chain), h_hash)
  39
  40 #define for_each_host_safe(host, pos, next, chain, table) \
  41         for ((chain) = (table); \
  42              (chain) < (table) + NLM_HOST_NRHASH; ++(chain)) \
  43                 hlist_for_each_entry_safe((host), (pos), (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         BUG_ON(!list_empty(&host->h_lockowners));
 181         BUG_ON(atomic_read(&host->h_count));
 182
 183         hlist_del_init(&host->h_hash);
 184
 185         nsm_unmonitor(host);
 186         nsm_release(host->h_nsmhandle);
 187
 188         clnt = host->h_rpcclnt;
 189         if (clnt != NULL)
 190                 rpc_shutdown_client(clnt);
 191         kfree(host);
 192
 193         ln->nrhosts--;
 194         nrhosts--;
 195 }
 196
 197 /**
 198  * nlmclnt_lookup_host - Find an NLM host handle matching a remote server
 199  * @sap: network address of server
 200  * @salen: length of server address
 201  * @protocol: transport protocol to use
 202  * @version: NLM protocol version
 203  * @hostname: '\0'-terminated hostname of server
 204  * @noresvport: 1 if non-privileged port should be used
 205  *
 206  * Returns an nlm_host structure that matches the passed-in
 207  * [server address, transport protocol, NLM version, server hostname].
 208  * If one doesn't already exist in the host cache, a new handle is
 209  * created and returned.
 210  */
 211 struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap,
 212                                      const size_t salen,
 213                                      const unsigned short protocol,
 214                                      const u32 version,
 215                                      const char *hostname,
 216                                      int noresvport,
 217                                      struct net *net)
 218 {
 219         struct nlm_lookup_host_info ni = {
 220                 .server         = 0,
 221                 .sap            = sap,
 222                 .salen          = salen,
 223                 .protocol       = protocol,
 224                 .version        = version,
 225                 .hostname       = hostname,
 226                 .hostname_len   = strlen(hostname),
 227                 .noresvport     = noresvport,
 228                 .net            = net,
 229         };
 230         struct hlist_head *chain;
 231         struct hlist_node *pos;
 232         struct nlm_host *host;
 233         struct nsm_handle *nsm = NULL;
 234         struct lockd_net *ln = net_generic(net, lockd_net_id);
 235
 236         dprintk("lockd: %s(host='%s', vers=%u, proto=%s)\n", __func__,
 237                         (hostname ? hostname : "<none>"), version,
 238                         (protocol == IPPROTO_UDP ? "udp" : "tcp"));
 239
 240         mutex_lock(&nlm_host_mutex);
 241
 242         chain = &nlm_client_hosts[nlm_hash_address(sap)];
 243         hlist_for_each_entry(host, pos, chain, h_hash) {
 244                 if (host->net != net)
 245                         continue;
 246                 if (!rpc_cmp_addr(nlm_addr(host), sap))
 247                         continue;
 248
 249                 /* Same address. Share an NSM handle if we already have one */
 250                 if (nsm == NULL)
 251                         nsm = host->h_nsmhandle;
 252
 253                 if (host->h_proto != protocol)
 254                         continue;
 255                 if (host->h_version != version)
 256                         continue;
 257
 258                 nlm_get_host(host);
 259                 dprintk("lockd: %s found host %s (%s)\n", __func__,
 260                         host->h_name, host->h_addrbuf);
 261                 goto out;
 262         }
 263
 264         host = nlm_alloc_host(&ni, nsm);
 265         if (unlikely(host == NULL))
 266                 goto out;
 267
 268         hlist_add_head(&host->h_hash, chain);
 269         ln->nrhosts++;
 270         nrhosts++;
 271
 272         dprintk("lockd: %s created host %s (%s)\n", __func__,
 273                 host->h_name, host->h_addrbuf);
 274
 275 out:
 276         mutex_unlock(&nlm_host_mutex);
 277         return host;
 278 }
 279
 280 /**
 281  * nlmclnt_release_host - release client nlm_host
 282  * @host: nlm_host to release
 283  *
 284  */
 285 void nlmclnt_release_host(struct nlm_host *host)
 286 {
 287         if (host == NULL)
 288                 return;
 289
 290         dprintk("lockd: release client host %s\n", host->h_name);
 291
 292         BUG_ON(atomic_read(&host->h_count) < 0);
 293         BUG_ON(host->h_server);
 294
 295         if (atomic_dec_and_test(&host->h_count)) {
 296                 BUG_ON(!list_empty(&host->h_lockowners));
 297                 BUG_ON(!list_empty(&host->h_granted));
 298                 BUG_ON(!list_empty(&host->h_reclaim));
 299
 300                 mutex_lock(&nlm_host_mutex);
 301                 nlm_destroy_host_locked(host);
 302                 mutex_unlock(&nlm_host_mutex);
 303         }
 304 }
 305
 306 /**
 307  * nlmsvc_lookup_host - Find an NLM host handle matching a remote client
 308  * @rqstp: incoming NLM request
 309  * @hostname: name of client host
 310  * @hostname_len: length of client hostname
 311  *
 312  * Returns an nlm_host structure that matches the [client address,
 313  * transport protocol, NLM version, client hostname] of the passed-in
 314  * NLM request.  If one doesn't already exist in the host cache, a
 315  * new handle is created and returned.
 316  *
 317  * Before possibly creating a new nlm_host, construct a sockaddr
 318  * for a specific source address in case the local system has
 319  * multiple network addresses.  The family of the address in
 320  * rq_daddr is guaranteed to be the same as the family of the
 321  * address in rq_addr, so it's safe to use the same family for
 322  * the source address.
 323  */
 324 struct nlm_host *nlmsvc_lookup_host(const struct svc_rqst *rqstp,
 325                                     const char *hostname,
 326                                     const size_t hostname_len)
 327 {
 328         struct hlist_head *chain;
 329         struct hlist_node *pos;
 330         struct nlm_host *host = NULL;
 331         struct nsm_handle *nsm = NULL;
 332         struct sockaddr *src_sap = svc_daddr(rqstp);
 333         size_t src_len = rqstp->rq_daddrlen;
 334         struct net *net = SVC_NET(rqstp);
 335         struct nlm_lookup_host_info ni = {
 336                 .server         = 1,
 337                 .sap            = svc_addr(rqstp),
 338                 .salen          = rqstp->rq_addrlen,
 339                 .protocol       = rqstp->rq_prot,
 340                 .version        = rqstp->rq_vers,
 341                 .hostname       = hostname,
 342                 .hostname_len   = hostname_len,
 343                 .net            = net,
 344         };
 345         struct lockd_net *ln = net_generic(net, lockd_net_id);
 346
 347         dprintk("lockd: %s(host='%*s', vers=%u, proto=%s)\n", __func__,
 348                         (int)hostname_len, hostname, rqstp->rq_vers,
 349                         (rqstp->rq_prot == IPPROTO_UDP ? "udp" : "tcp"));
 350
 351         mutex_lock(&nlm_host_mutex);
 352
 353         if (time_after_eq(jiffies, ln->next_gc))
 354                 nlm_gc_hosts(net);
 355
 356         chain = &nlm_server_hosts[nlm_hash_address(ni.sap)];
 357         hlist_for_each_entry(host, pos, chain, h_hash) {
 358                 if (host->net != net)
 359                         continue;
 360                 if (!rpc_cmp_addr(nlm_addr(host), ni.sap))
 361                         continue;
 362
 363                 /* Same address. Share an NSM handle if we already have one */
 364                 if (nsm == NULL)
 365                         nsm = host->h_nsmhandle;
 366
 367                 if (host->h_proto != ni.protocol)
 368                         continue;
 369                 if (host->h_version != ni.version)
 370                         continue;
 371                 if (!rpc_cmp_addr(nlm_srcaddr(host), src_sap))
 372                         continue;
 373
 374                 /* Move to head of hash chain. */
 375                 hlist_del(&host->h_hash);
 376                 hlist_add_head(&host->h_hash, chain);
 377
 378                 nlm_get_host(host);
 379                 dprintk("lockd: %s found host %s (%s)\n",
 380                         __func__, host->h_name, host->h_addrbuf);
 381                 goto out;
 382         }
 383
 384         host = nlm_alloc_host(&ni, nsm);
 385         if (unlikely(host == NULL))
 386                 goto out;
 387
 388         memcpy(nlm_srcaddr(host), src_sap, src_len);
 389         host->h_srcaddrlen = src_len;
 390         hlist_add_head(&host->h_hash, chain);
 391         ln->nrhosts++;
 392         nrhosts++;
 393
 394         dprintk("lockd: %s created host %s (%s)\n",
 395                 __func__, host->h_name, host->h_addrbuf);
 396
 397 out:
 398         mutex_unlock(&nlm_host_mutex);
 399         return host;
 400 }
 401
 402 /**
 403  * nlmsvc_release_host - release server nlm_host
 404  * @host: nlm_host to release
 405  *
 406  * Host is destroyed later in nlm_gc_host().
 407  */
 408 void nlmsvc_release_host(struct nlm_host *host)
 409 {
 410         if (host == NULL)
 411                 return;
 412
 413         dprintk("lockd: release server host %s\n", host->h_name);
 414
 415         BUG_ON(atomic_read(&host->h_count) < 0);
 416         BUG_ON(!host->h_server);
 417         atomic_dec(&host->h_count);
 418 }
 419
 420 /*
 421  * Create the NLM RPC client for an NLM peer
 422  */
 423 struct rpc_clnt *
 424 nlm_bind_host(struct nlm_host *host)
 425 {
 426         struct rpc_clnt *clnt;
 427
 428         dprintk("lockd: nlm_bind_host %s (%s)\n",
 429                         host->h_name, host->h_addrbuf);
 430
 431         /* Lock host handle */
 432         mutex_lock(&host->h_mutex);
 433
 434         /* If we've already created an RPC client, check whether
 435          * RPC rebind is required
 436          */
 437         if ((clnt = host->h_rpcclnt) != NULL) {
 438                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 439                         rpc_force_rebind(clnt);
 440                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 441                         dprintk("lockd: next rebind in %lu jiffies\n",
 442                                         host->h_nextrebind - jiffies);
 443                 }
 444         } else {
 445                 unsigned long increment = nlmsvc_timeout;
 446                 struct rpc_timeout timeparms = {
 447                         .to_initval     = increment,
 448                         .to_increment   = increment,
 449                         .to_maxval      = increment * 6UL,
 450                         .to_retries     = 5U,
 451                 };
 452                 struct rpc_create_args args = {
 453                         .net            = host->net,
 454                         .protocol       = host->h_proto,
 455                         .address        = nlm_addr(host),
 456                         .addrsize       = host->h_addrlen,
 457                         .timeout        = &timeparms,
 458                         .servername     = host->h_name,
 459                         .program        = &nlm_program,
 460                         .version        = host->h_version,
 461                         .authflavor     = RPC_AUTH_UNIX,
 462                         .flags          = (RPC_CLNT_CREATE_NOPING |
 463                                            RPC_CLNT_CREATE_AUTOBIND),
 464                 };
 465
 466                 /*
 467                  * lockd retries server side blocks automatically so we want
 468                  * those to be soft RPC calls. Client side calls need to be
 469                  * hard RPC tasks.
 470                  */
 471                 if (!host->h_server)
 472                         args.flags |= RPC_CLNT_CREATE_HARDRTRY;
 473                 if (host->h_noresvport)
 474                         args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
 475                 if (host->h_srcaddrlen)
 476                         args.saddress = nlm_srcaddr(host);
 477
 478                 clnt = rpc_create(&args);
 479                 if (!IS_ERR(clnt))
 480                         host->h_rpcclnt = clnt;
 481                 else {
 482                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 483                         clnt = NULL;
 484                 }
 485         }
 486
 487         mutex_unlock(&host->h_mutex);
 488         return clnt;
 489 }
 490
 491 /*
 492  * Force a portmap lookup of the remote lockd port
 493  */
 494 void
 495 nlm_rebind_host(struct nlm_host *host)
 496 {
 497         dprintk("lockd: rebind host %s\n", host->h_name);
 498         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 499                 rpc_force_rebind(host->h_rpcclnt);
 500                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 501         }
 502 }
 503
 504 /*
 505  * Increment NLM host count
 506  */
 507 struct nlm_host * nlm_get_host(struct nlm_host *host)
 508 {
 509         if (host) {
 510                 dprintk("lockd: get host %s\n", host->h_name);
 511                 atomic_inc(&host->h_count);
 512                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 513         }
 514         return host;
 515 }
 516
 517 static struct nlm_host *next_host_state(struct hlist_head *cache,
 518                                         struct nsm_handle *nsm,
 519                                         const struct nlm_reboot *info)
 520 {
 521         struct nlm_host *host;
 522         struct hlist_head *chain;
 523         struct hlist_node *pos;
 524
 525         mutex_lock(&nlm_host_mutex);
 526         for_each_host(host, pos, chain, cache) {
 527                 if (host->h_nsmhandle == nsm
 528                     && host->h_nsmstate != info->state) {
 529                         host->h_nsmstate = info->state;
 530                         host->h_state++;
 531
 532                         nlm_get_host(host);
 533                         mutex_unlock(&nlm_host_mutex);
 534                         return host;
 535                 }
 536         }
 537
 538         mutex_unlock(&nlm_host_mutex);
 539         return NULL;
 540 }
 541
 542 /**
 543  * nlm_host_rebooted - Release all resources held by rebooted host
 544  * @info: pointer to decoded results of NLM_SM_NOTIFY call
 545  *
 546  * We were notified that the specified host has rebooted.  Release
 547  * all resources held by that peer.
 548  */
 549 void nlm_host_rebooted(const struct nlm_reboot *info)
 550 {
 551         struct nsm_handle *nsm;
 552         struct nlm_host *host;
 553
 554         nsm = nsm_reboot_lookup(info);
 555         if (unlikely(nsm == NULL))
 556                 return;
 557
 558         /* Mark all hosts tied to this NSM state as having rebooted.
 559          * We run the loop repeatedly, because we drop the host table
 560          * lock for this.
 561          * To avoid processing a host several times, we match the nsmstate.
 562          */
 563         while ((host = next_host_state(nlm_server_hosts, nsm, info)) != NULL) {
 564                 nlmsvc_free_host_resources(host);
 565                 nlmsvc_release_host(host);
 566         }
 567         while ((host = next_host_state(nlm_client_hosts, nsm, info)) != NULL) {
 568                 nlmclnt_recovery(host);
 569                 nlmclnt_release_host(host);
 570         }
 571
 572         nsm_release(nsm);
 573 }
 574
 575 static void nlm_complain_hosts(struct net *net)
 576 {
 577         struct hlist_head *chain;
 578         struct hlist_node *pos;
 579         struct nlm_host *host;
 580
 581         if (net) {
 582                 struct lockd_net *ln = net_generic(net, lockd_net_id);
 583
 584                 if (ln->nrhosts == 0)
 585                         return;
 586                 printk(KERN_WARNING "lockd: couldn't shutdown host module for net %p!\n", net);
 587                 dprintk("lockd: %lu hosts left in net %p:\n", ln->nrhosts, net);
 588         } else {
 589                 if (nrhosts == 0)
 590                         return;
 591                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 592                 dprintk("lockd: %lu hosts left:\n", nrhosts);
 593         }
 594
 595         for_each_host(host, pos, chain, nlm_server_hosts) {
 596                 if (net && host->net != net)
 597                         continue;
 598                 dprintk("       %s (cnt %d use %d exp %ld net %p)\n",
 599                         host->h_name, atomic_read(&host->h_count),
 600                         host->h_inuse, host->h_expires, host->net);
 601         }
 602 }
 603
 604 void
 605 nlm_shutdown_hosts_net(struct net *net)
 606 {
 607         struct hlist_head *chain;
 608         struct hlist_node *pos;
 609         struct nlm_host *host;
 610
 611         mutex_lock(&nlm_host_mutex);
 612
 613         /* First, make all hosts eligible for gc */
 614         dprintk("lockd: nuking all hosts in net %p...\n", net);
 615         for_each_host(host, pos, chain, nlm_server_hosts) {
 616                 if (net && host->net != net)
 617                         continue;
 618                 host->h_expires = jiffies - 1;
 619                 if (host->h_rpcclnt) {
 620                         rpc_shutdown_client(host->h_rpcclnt);
 621                         host->h_rpcclnt = NULL;
 622                 }
 623         }
 624
 625         /* Then, perform a garbage collection pass */
 626         nlm_gc_hosts(net);
 627         mutex_unlock(&nlm_host_mutex);
 628
 629         nlm_complain_hosts(net);
 630 }
 631
 632 /*
 633  * Shut down the hosts module.
 634  * Note that this routine is called only at server shutdown time.
 635  */
 636 void
 637 nlm_shutdown_hosts(void)
 638 {
 639         dprintk("lockd: shutting down host module\n");
 640         nlm_shutdown_hosts_net(NULL);
 641 }
 642
 643 /*
 644  * Garbage collect any unused NLM hosts.
 645  * This GC combines reference counting for async operations with
 646  * mark & sweep for resources held by remote clients.
 647  */
 648 static void
 649 nlm_gc_hosts(struct net *net)
 650 {
 651         struct hlist_head *chain;
 652         struct hlist_node *pos, *next;
 653         struct nlm_host *host;
 654
 655         dprintk("lockd: host garbage collection for net %p\n", net);
 656         for_each_host(host, pos, chain, nlm_server_hosts) {
 657                 if (net && host->net != net)
 658                         continue;
 659                 host->h_inuse = 0;
 660         }
 661
 662         /* Mark all hosts that hold locks, blocks or shares */
 663         nlmsvc_mark_resources(net);
 664
 665         for_each_host_safe(host, pos, next, chain, nlm_server_hosts) {
 666                 if (net && host->net != net)
 667                         continue;
 668                 if (atomic_read(&host->h_count) || host->h_inuse
 669                  || time_before(jiffies, host->h_expires)) {
 670                         dprintk("nlm_gc_hosts skipping %s "
 671                                 "(cnt %d use %d exp %ld net %p)\n",
 672                                 host->h_name, atomic_read(&host->h_count),
 673                                 host->h_inuse, host->h_expires, host->net);
 674                         continue;
 675                 }
 676                 nlm_destroy_host_locked(host);
 677         }
 678
 679         if (net) {
 680                 struct lockd_net *ln = net_generic(net, lockd_net_id);
 681
 682                 ln->next_gc = jiffies + NLM_HOST_COLLECT;
 683         }
 684 }