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   1 /*
   2  * linux/fs/lockd/host.c
   3  *
   4  * Management for NLM peer hosts. The nlm_host struct is shared
   5  * between client and server implementation. The only reason to
   6  * do so is to reduce code bloat.
   7  *
   8  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/slab.h>
  13 #include <linux/in.h>
  14 #include <linux/sunrpc/clnt.h>
  15 #include <linux/sunrpc/svc.h>
  16 #include <linux/lockd/lockd.h>
  17 #include <linux/lockd/sm_inter.h>
  18 #include <linux/mutex.h>
  19
  20
  21 #define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
  22 #define NLM_HOST_NRHASH         32
  23 #define NLM_ADDRHASH(addr)      (ntohl(addr) & (NLM_HOST_NRHASH-1))
  24 #define NLM_HOST_REBIND         (60 * HZ)
  25 #define NLM_HOST_EXPIRE         (300 * HZ)
  26 #define NLM_HOST_COLLECT        (120 * HZ)
  27
  28 static struct hlist_head        nlm_hosts[NLM_HOST_NRHASH];
  29 static unsigned long            next_gc;
  30 static int                      nrhosts;
  31 static DEFINE_MUTEX(nlm_host_mutex);
  32
  33
  34 static void                     nlm_gc_hosts(void);
  35 static struct nsm_handle *      __nsm_find(const struct sockaddr_in *,
  36                                         const char *, unsigned int, int);
  37 static struct nsm_handle *      nsm_find(const struct sockaddr_in *sin,
  38                                          const char *hostname,
  39                                          unsigned int hostname_len);
  40
  41 /*
  42  * Common host lookup routine for server & client
  43  */
  44 static struct nlm_host *nlm_lookup_host(int server,
  45                                         const struct sockaddr_in *sin,
  46                                         int proto, u32 version,
  47                                         const char *hostname,
  48                                         unsigned int hostname_len,
  49                                         const struct sockaddr_in *ssin)
  50 {
  51         struct hlist_head *chain;
  52         struct hlist_node *pos;
  53         struct nlm_host *host;
  54         struct nsm_handle *nsm = NULL;
  55         int             hash;
  56
  57         dprintk("lockd: nlm_lookup_host("NIPQUAD_FMT"->"NIPQUAD_FMT
  58                         ", p=%d, v=%u, my role=%s, name=%.*s)\n",
  59                         NIPQUAD(ssin->sin_addr.s_addr),
  60                         NIPQUAD(sin->sin_addr.s_addr), proto, version,
  61                         server? "server" : "client",
  62                         hostname_len,
  63                         hostname? hostname : "<none>");
  64
  65
  66         hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
  67
  68         /* Lock hash table */
  69         mutex_lock(&nlm_host_mutex);
  70
  71         if (time_after_eq(jiffies, next_gc))
  72                 nlm_gc_hosts();
  73
  74         /* We may keep several nlm_host objects for a peer, because each
  75          * nlm_host is identified by
  76          * (address, protocol, version, server/client)
  77          * We could probably simplify this a little by putting all those
  78          * different NLM rpc_clients into one single nlm_host object.
  79          * This would allow us to have one nlm_host per address.
  80          */
  81         chain = &nlm_hosts[hash];
  82         hlist_for_each_entry(host, pos, chain, h_hash) {
  83                 if (!nlm_cmp_addr(&host->h_addr, sin))
  84                         continue;
  85
  86                 /* See if we have an NSM handle for this client */
  87                 if (!nsm)
  88                         nsm = host->h_nsmhandle;
  89
  90                 if (host->h_proto != proto)
  91                         continue;
  92                 if (host->h_version != version)
  93                         continue;
  94                 if (host->h_server != server)
  95                         continue;
  96                 if (!nlm_cmp_addr(&host->h_saddr, ssin))
  97                         continue;
  98
  99                 /* Move to head of hash chain. */
 100                 hlist_del(&host->h_hash);
 101                 hlist_add_head(&host->h_hash, chain);
 102
 103                 nlm_get_host(host);
 104                 goto out;
 105         }
 106         if (nsm)
 107                 atomic_inc(&nsm->sm_count);
 108
 109         host = NULL;
 110
 111         /* Sadly, the host isn't in our hash table yet. See if
 112          * we have an NSM handle for it. If not, create one.
 113          */
 114         if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
 115                 goto out;
 116
 117         host = kzalloc(sizeof(*host), GFP_KERNEL);
 118         if (!host) {
 119                 nsm_release(nsm);
 120                 goto out;
 121         }
 122         host->h_name       = nsm->sm_name;
 123         host->h_addr       = *sin;
 124         host->h_addr.sin_port = 0;      /* ouch! */
 125         host->h_saddr      = *ssin;
 126         host->h_version    = version;
 127         host->h_proto      = proto;
 128         host->h_rpcclnt    = NULL;
 129         mutex_init(&host->h_mutex);
 130         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 131         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 132         atomic_set(&host->h_count, 1);
 133         init_waitqueue_head(&host->h_gracewait);
 134         init_rwsem(&host->h_rwsem);
 135         host->h_state      = 0;                 /* pseudo NSM state */
 136         host->h_nsmstate   = 0;                 /* real NSM state */
 137         host->h_nsmhandle  = nsm;
 138         host->h_server     = server;
 139         hlist_add_head(&host->h_hash, chain);
 140         INIT_LIST_HEAD(&host->h_lockowners);
 141         spin_lock_init(&host->h_lock);
 142         INIT_LIST_HEAD(&host->h_granted);
 143         INIT_LIST_HEAD(&host->h_reclaim);
 144
 145         nrhosts++;
 146 out:
 147         mutex_unlock(&nlm_host_mutex);
 148         return host;
 149 }
 150
 151 /*
 152  * Destroy a host
 153  */
 154 static void
 155 nlm_destroy_host(struct nlm_host *host)
 156 {
 157         struct rpc_clnt *clnt;
 158
 159         BUG_ON(!list_empty(&host->h_lockowners));
 160         BUG_ON(atomic_read(&host->h_count));
 161
 162         /*
 163          * Release NSM handle and unmonitor host.
 164          */
 165         nsm_unmonitor(host);
 166
 167         clnt = host->h_rpcclnt;
 168         if (clnt != NULL)
 169                 rpc_shutdown_client(clnt);
 170         kfree(host);
 171 }
 172
 173 /*
 174  * Find an NLM server handle in the cache. If there is none, create it.
 175  */
 176 struct nlm_host *nlmclnt_lookup_host(const struct sockaddr_in *sin,
 177                                      int proto, u32 version,
 178                                      const char *hostname,
 179                                      unsigned int hostname_len)
 180 {
 181         struct sockaddr_in ssin = {0};
 182
 183         return nlm_lookup_host(0, sin, proto, version,
 184                                hostname, hostname_len, &ssin);
 185 }
 186
 187 /*
 188  * Find an NLM client handle in the cache. If there is none, create it.
 189  */
 190 struct nlm_host *
 191 nlmsvc_lookup_host(struct svc_rqst *rqstp,
 192                         const char *hostname, unsigned int hostname_len)
 193 {
 194         struct sockaddr_in ssin = {0};
 195
 196         ssin.sin_addr = rqstp->rq_daddr.addr;
 197         return nlm_lookup_host(1, svc_addr_in(rqstp),
 198                                rqstp->rq_prot, rqstp->rq_vers,
 199                                hostname, hostname_len, &ssin);
 200 }
 201
 202 /*
 203  * Create the NLM RPC client for an NLM peer
 204  */
 205 struct rpc_clnt *
 206 nlm_bind_host(struct nlm_host *host)
 207 {
 208         struct rpc_clnt *clnt;
 209
 210         dprintk("lockd: nlm_bind_host("NIPQUAD_FMT"->"NIPQUAD_FMT")\n",
 211                         NIPQUAD(host->h_saddr.sin_addr),
 212                         NIPQUAD(host->h_addr.sin_addr));
 213
 214         /* Lock host handle */
 215         mutex_lock(&host->h_mutex);
 216
 217         /* If we've already created an RPC client, check whether
 218          * RPC rebind is required
 219          */
 220         if ((clnt = host->h_rpcclnt) != NULL) {
 221                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 222                         rpc_force_rebind(clnt);
 223                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 224                         dprintk("lockd: next rebind in %ld jiffies\n",
 225                                         host->h_nextrebind - jiffies);
 226                 }
 227         } else {
 228                 unsigned long increment = nlmsvc_timeout;
 229                 struct rpc_timeout timeparms = {
 230                         .to_initval     = increment,
 231                         .to_increment   = increment,
 232                         .to_maxval      = increment * 6UL,
 233                         .to_retries     = 5U,
 234                 };
 235                 struct rpc_create_args args = {
 236                         .protocol       = host->h_proto,
 237                         .address        = (struct sockaddr *)&host->h_addr,
 238                         .addrsize       = sizeof(host->h_addr),
 239                         .saddress       = (struct sockaddr *)&host->h_saddr,
 240                         .timeout        = &timeparms,
 241                         .servername     = host->h_name,
 242                         .program        = &nlm_program,
 243                         .version        = host->h_version,
 244                         .authflavor     = RPC_AUTH_UNIX,
 245                         .flags          = (RPC_CLNT_CREATE_NOPING |
 246                                            RPC_CLNT_CREATE_AUTOBIND),
 247                 };
 248
 249                 /*
 250                  * lockd retries server side blocks automatically so we want
 251                  * those to be soft RPC calls. Client side calls need to be
 252                  * hard RPC tasks.
 253                  */
 254                 if (!host->h_server)
 255                         args.flags |= RPC_CLNT_CREATE_HARDRTRY;
 256
 257                 clnt = rpc_create(&args);
 258                 if (!IS_ERR(clnt))
 259                         host->h_rpcclnt = clnt;
 260                 else {
 261                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 262                         clnt = NULL;
 263                 }
 264         }
 265
 266         mutex_unlock(&host->h_mutex);
 267         return clnt;
 268 }
 269
 270 /*
 271  * Force a portmap lookup of the remote lockd port
 272  */
 273 void
 274 nlm_rebind_host(struct nlm_host *host)
 275 {
 276         dprintk("lockd: rebind host %s\n", host->h_name);
 277         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 278                 rpc_force_rebind(host->h_rpcclnt);
 279                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 280         }
 281 }
 282
 283 /*
 284  * Increment NLM host count
 285  */
 286 struct nlm_host * nlm_get_host(struct nlm_host *host)
 287 {
 288         if (host) {
 289                 dprintk("lockd: get host %s\n", host->h_name);
 290                 atomic_inc(&host->h_count);
 291                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 292         }
 293         return host;
 294 }
 295
 296 /*
 297  * Release NLM host after use
 298  */
 299 void nlm_release_host(struct nlm_host *host)
 300 {
 301         if (host != NULL) {
 302                 dprintk("lockd: release host %s\n", host->h_name);
 303                 BUG_ON(atomic_read(&host->h_count) < 0);
 304                 if (atomic_dec_and_test(&host->h_count)) {
 305                         BUG_ON(!list_empty(&host->h_lockowners));
 306                         BUG_ON(!list_empty(&host->h_granted));
 307                         BUG_ON(!list_empty(&host->h_reclaim));
 308                 }
 309         }
 310 }
 311
 312 /*
 313  * We were notified that the host indicated by address &sin
 314  * has rebooted.
 315  * Release all resources held by that peer.
 316  */
 317 void nlm_host_rebooted(const struct sockaddr_in *sin,
 318                                 const char *hostname,
 319                                 unsigned int hostname_len,
 320                                 u32 new_state)
 321 {
 322         struct hlist_head *chain;
 323         struct hlist_node *pos;
 324         struct nsm_handle *nsm;
 325         struct nlm_host *host;
 326
 327         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 328                         hostname, NIPQUAD(sin->sin_addr));
 329
 330         /* Find the NSM handle for this peer */
 331         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 332                 return;
 333
 334         /* When reclaiming locks on this peer, make sure that
 335          * we set up a new notification */
 336         nsm->sm_monitored = 0;
 337
 338         /* Mark all hosts tied to this NSM state as having rebooted.
 339          * We run the loop repeatedly, because we drop the host table
 340          * lock for this.
 341          * To avoid processing a host several times, we match the nsmstate.
 342          */
 343 again:  mutex_lock(&nlm_host_mutex);
 344         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 345                 hlist_for_each_entry(host, pos, chain, h_hash) {
 346                         if (host->h_nsmhandle == nsm
 347                          && host->h_nsmstate != new_state) {
 348                                 host->h_nsmstate = new_state;
 349                                 host->h_state++;
 350
 351                                 nlm_get_host(host);
 352                                 mutex_unlock(&nlm_host_mutex);
 353
 354                                 if (host->h_server) {
 355                                         /* We're server for this guy, just ditch
 356                                          * all the locks he held. */
 357                                         nlmsvc_free_host_resources(host);
 358                                 } else {
 359                                         /* He's the server, initiate lock recovery. */
 360                                         nlmclnt_recovery(host);
 361                                 }
 362
 363                                 nlm_release_host(host);
 364                                 goto again;
 365                         }
 366                 }
 367         }
 368
 369         mutex_unlock(&nlm_host_mutex);
 370 }
 371
 372 /*
 373  * Shut down the hosts module.
 374  * Note that this routine is called only at server shutdown time.
 375  */
 376 void
 377 nlm_shutdown_hosts(void)
 378 {
 379         struct hlist_head *chain;
 380         struct hlist_node *pos;
 381         struct nlm_host *host;
 382
 383         dprintk("lockd: shutting down host module\n");
 384         mutex_lock(&nlm_host_mutex);
 385
 386         /* First, make all hosts eligible for gc */
 387         dprintk("lockd: nuking all hosts...\n");
 388         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 389                 hlist_for_each_entry(host, pos, chain, h_hash) {
 390                         host->h_expires = jiffies - 1;
 391                         if (host->h_rpcclnt) {
 392                                 rpc_shutdown_client(host->h_rpcclnt);
 393                                 host->h_rpcclnt = NULL;
 394                         }
 395                 }
 396         }
 397
 398         /* Then, perform a garbage collection pass */
 399         nlm_gc_hosts();
 400         mutex_unlock(&nlm_host_mutex);
 401
 402         /* complain if any hosts are left */
 403         if (nrhosts) {
 404                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 405                 dprintk("lockd: %d hosts left:\n", nrhosts);
 406                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 407                         hlist_for_each_entry(host, pos, chain, h_hash) {
 408                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 409                                         host->h_name, atomic_read(&host->h_count),
 410                                         host->h_inuse, host->h_expires);
 411                         }
 412                 }
 413         }
 414 }
 415
 416 /*
 417  * Garbage collect any unused NLM hosts.
 418  * This GC combines reference counting for async operations with
 419  * mark & sweep for resources held by remote clients.
 420  */
 421 static void
 422 nlm_gc_hosts(void)
 423 {
 424         struct hlist_head *chain;
 425         struct hlist_node *pos, *next;
 426         struct nlm_host *host;
 427
 428         dprintk("lockd: host garbage collection\n");
 429         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 430                 hlist_for_each_entry(host, pos, chain, h_hash)
 431                         host->h_inuse = 0;
 432         }
 433
 434         /* Mark all hosts that hold locks, blocks or shares */
 435         nlmsvc_mark_resources();
 436
 437         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 438                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 439                         if (atomic_read(&host->h_count) || host->h_inuse
 440                          || time_before(jiffies, host->h_expires)) {
 441                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 442                                         host->h_name, atomic_read(&host->h_count),
 443                                         host->h_inuse, host->h_expires);
 444                                 continue;
 445                         }
 446                         dprintk("lockd: delete host %s\n", host->h_name);
 447                         hlist_del_init(&host->h_hash);
 448
 449                         nlm_destroy_host(host);
 450                         nrhosts--;
 451                 }
 452         }
 453
 454         next_gc = jiffies + NLM_HOST_COLLECT;
 455 }
 456
 457
 458 /*
 459  * Manage NSM handles
 460  */
 461 static LIST_HEAD(nsm_handles);
 462 static DEFINE_SPINLOCK(nsm_lock);
 463
 464 static struct nsm_handle *
 465 __nsm_find(const struct sockaddr_in *sin,
 466                 const char *hostname, unsigned int hostname_len,
 467                 int create)
 468 {
 469         struct nsm_handle *nsm = NULL;
 470         struct nsm_handle *pos;
 471
 472         if (!sin)
 473                 return NULL;
 474
 475         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 476                 if (printk_ratelimit()) {
 477                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 478                                             "in NFS lock request\n",
 479                                 hostname_len, hostname);
 480                 }
 481                 return NULL;
 482         }
 483
 484 retry:
 485         spin_lock(&nsm_lock);
 486         list_for_each_entry(pos, &nsm_handles, sm_link) {
 487
 488                 if (hostname && nsm_use_hostnames) {
 489                         if (strlen(pos->sm_name) != hostname_len
 490                          || memcmp(pos->sm_name, hostname, hostname_len))
 491                                 continue;
 492                 } else if (!nlm_cmp_addr(&pos->sm_addr, sin))
 493                         continue;
 494                 atomic_inc(&pos->sm_count);
 495                 kfree(nsm);
 496                 nsm = pos;
 497                 goto found;
 498         }
 499         if (nsm) {
 500                 list_add(&nsm->sm_link, &nsm_handles);
 501                 goto found;
 502         }
 503         spin_unlock(&nsm_lock);
 504
 505         if (!create)
 506                 return NULL;
 507
 508         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 509         if (nsm == NULL)
 510                 return NULL;
 511
 512         nsm->sm_addr = *sin;
 513         nsm->sm_name = (char *) (nsm + 1);
 514         memcpy(nsm->sm_name, hostname, hostname_len);
 515         nsm->sm_name[hostname_len] = '\0';
 516         atomic_set(&nsm->sm_count, 1);
 517         goto retry;
 518
 519 found:
 520         spin_unlock(&nsm_lock);
 521         return nsm;
 522 }
 523
 524 static struct nsm_handle *
 525 nsm_find(const struct sockaddr_in *sin, const char *hostname,
 526          unsigned int hostname_len)
 527 {
 528         return __nsm_find(sin, hostname, hostname_len, 1);
 529 }
 530
 531 /*
 532  * Release an NSM handle
 533  */
 534 void
 535 nsm_release(struct nsm_handle *nsm)
 536 {
 537         if (!nsm)
 538                 return;
 539         if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
 540                 list_del(&nsm->sm_link);
 541                 spin_unlock(&nsm_lock);
 542                 kfree(nsm);
 543         }
 544 }