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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_MAX            64
  23 #define NLM_HOST_NRHASH         32
  24 #define NLM_ADDRHASH(addr)      (ntohl(addr) & (NLM_HOST_NRHASH-1))
  25 #define NLM_HOST_REBIND         (60 * HZ)
  26 #define NLM_HOST_EXPIRE         ((nrhosts > NLM_HOST_MAX)? 300 * HZ : 120 * HZ)
  27 #define NLM_HOST_COLLECT        ((nrhosts > NLM_HOST_MAX)? 120 * HZ :  60 * HZ)
  28
  29 static struct hlist_head        nlm_hosts[NLM_HOST_NRHASH];
  30 static unsigned long            next_gc;
  31 static int                      nrhosts;
  32 static DEFINE_MUTEX(nlm_host_mutex);
  33
  34
  35 static void                     nlm_gc_hosts(void);
  36 static struct nsm_handle *      __nsm_find(const struct sockaddr_in *,
  37                                         const char *, unsigned int, int);
  38 static struct nsm_handle *      nsm_find(const struct sockaddr_in *sin,
  39                                          const char *hostname,
  40                                          unsigned int hostname_len);
  41
  42 /*
  43  * Common host lookup routine for server & client
  44  */
  45 static struct nlm_host *
  46 nlm_lookup_host(int server, const struct sockaddr_in *sin,
  47                 int proto, int version, 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=%d, 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         if (++nrhosts > NLM_HOST_MAX)
 146                 next_gc = 0;
 147
 148 out:
 149         mutex_unlock(&nlm_host_mutex);
 150         return host;
 151 }
 152
 153 /*
 154  * Destroy a host
 155  */
 156 static void
 157 nlm_destroy_host(struct nlm_host *host)
 158 {
 159         struct rpc_clnt *clnt;
 160
 161         BUG_ON(!list_empty(&host->h_lockowners));
 162         BUG_ON(atomic_read(&host->h_count));
 163
 164         /*
 165          * Release NSM handle and unmonitor host.
 166          */
 167         nsm_unmonitor(host);
 168
 169         clnt = host->h_rpcclnt;
 170         if (clnt != NULL)
 171                 rpc_shutdown_client(clnt);
 172         kfree(host);
 173 }
 174
 175 /*
 176  * Find an NLM server handle in the cache. If there is none, create it.
 177  */
 178 struct nlm_host *
 179 nlmclnt_lookup_host(const struct sockaddr_in *sin, int proto, int version,
 180                         const char *hostname, unsigned int hostname_len)
 181 {
 182         struct sockaddr_in ssin = {0};
 183
 184         return nlm_lookup_host(0, sin, proto, version,
 185                                hostname, hostname_len, &ssin);
 186 }
 187
 188 /*
 189  * Find an NLM client handle in the cache. If there is none, create it.
 190  */
 191 struct nlm_host *
 192 nlmsvc_lookup_host(struct svc_rqst *rqstp,
 193                         const char *hostname, unsigned int hostname_len)
 194 {
 195         struct sockaddr_in ssin = {0};
 196
 197         ssin.sin_addr = rqstp->rq_daddr.addr;
 198         return nlm_lookup_host(1, svc_addr_in(rqstp),
 199                                rqstp->rq_prot, rqstp->rq_vers,
 200                                hostname, hostname_len, &ssin);
 201 }
 202
 203 /*
 204  * Create the NLM RPC client for an NLM peer
 205  */
 206 struct rpc_clnt *
 207 nlm_bind_host(struct nlm_host *host)
 208 {
 209         struct rpc_clnt *clnt;
 210
 211         dprintk("lockd: nlm_bind_host("NIPQUAD_FMT"->"NIPQUAD_FMT")\n",
 212                         NIPQUAD(host->h_saddr.sin_addr),
 213                         NIPQUAD(host->h_addr.sin_addr));
 214
 215         /* Lock host handle */
 216         mutex_lock(&host->h_mutex);
 217
 218         /* If we've already created an RPC client, check whether
 219          * RPC rebind is required
 220          */
 221         if ((clnt = host->h_rpcclnt) != NULL) {
 222                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 223                         rpc_force_rebind(clnt);
 224                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 225                         dprintk("lockd: next rebind in %ld jiffies\n",
 226                                         host->h_nextrebind - jiffies);
 227                 }
 228         } else {
 229                 unsigned long increment = nlmsvc_timeout;
 230                 struct rpc_timeout timeparms = {
 231                         .to_initval     = increment,
 232                         .to_increment   = increment,
 233                         .to_maxval      = increment * 6UL,
 234                         .to_retries     = 5U,
 235                 };
 236                 struct rpc_create_args args = {
 237                         .protocol       = host->h_proto,
 238                         .address        = (struct sockaddr *)&host->h_addr,
 239                         .addrsize       = sizeof(host->h_addr),
 240                         .saddress       = (struct sockaddr *)&host->h_saddr,
 241                         .timeout        = &timeparms,
 242                         .servername     = host->h_name,
 243                         .program        = &nlm_program,
 244                         .version        = host->h_version,
 245                         .authflavor     = RPC_AUTH_UNIX,
 246                         .flags          = (RPC_CLNT_CREATE_NOPING |
 247                                            RPC_CLNT_CREATE_AUTOBIND),
 248                 };
 249
 250                 /*
 251                  * lockd retries server side blocks automatically so we want
 252                  * those to be soft RPC calls. Client side calls need to be
 253                  * hard RPC tasks.
 254                  */
 255                 if (!host->h_server)
 256                         args.flags |= RPC_CLNT_CREATE_HARDRTRY;
 257
 258                 clnt = rpc_create(&args);
 259                 if (!IS_ERR(clnt))
 260                         host->h_rpcclnt = clnt;
 261                 else {
 262                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 263                         clnt = NULL;
 264                 }
 265         }
 266
 267         mutex_unlock(&host->h_mutex);
 268         return clnt;
 269 }
 270
 271 /*
 272  * Force a portmap lookup of the remote lockd port
 273  */
 274 void
 275 nlm_rebind_host(struct nlm_host *host)
 276 {
 277         dprintk("lockd: rebind host %s\n", host->h_name);
 278         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 279                 rpc_force_rebind(host->h_rpcclnt);
 280                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 281         }
 282 }
 283
 284 /*
 285  * Increment NLM host count
 286  */
 287 struct nlm_host * nlm_get_host(struct nlm_host *host)
 288 {
 289         if (host) {
 290                 dprintk("lockd: get host %s\n", host->h_name);
 291                 atomic_inc(&host->h_count);
 292                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 293         }
 294         return host;
 295 }
 296
 297 /*
 298  * Release NLM host after use
 299  */
 300 void nlm_release_host(struct nlm_host *host)
 301 {
 302         if (host != NULL) {
 303                 dprintk("lockd: release host %s\n", host->h_name);
 304                 BUG_ON(atomic_read(&host->h_count) < 0);
 305                 if (atomic_dec_and_test(&host->h_count)) {
 306                         BUG_ON(!list_empty(&host->h_lockowners));
 307                         BUG_ON(!list_empty(&host->h_granted));
 308                         BUG_ON(!list_empty(&host->h_reclaim));
 309                 }
 310         }
 311 }
 312
 313 /*
 314  * We were notified that the host indicated by address &sin
 315  * has rebooted.
 316  * Release all resources held by that peer.
 317  */
 318 void nlm_host_rebooted(const struct sockaddr_in *sin,
 319                                 const char *hostname,
 320                                 unsigned int hostname_len,
 321                                 u32 new_state)
 322 {
 323         struct hlist_head *chain;
 324         struct hlist_node *pos;
 325         struct nsm_handle *nsm;
 326         struct nlm_host *host;
 327
 328         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 329                         hostname, NIPQUAD(sin->sin_addr));
 330
 331         /* Find the NSM handle for this peer */
 332         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 333                 return;
 334
 335         /* When reclaiming locks on this peer, make sure that
 336          * we set up a new notification */
 337         nsm->sm_monitored = 0;
 338
 339         /* Mark all hosts tied to this NSM state as having rebooted.
 340          * We run the loop repeatedly, because we drop the host table
 341          * lock for this.
 342          * To avoid processing a host several times, we match the nsmstate.
 343          */
 344 again:  mutex_lock(&nlm_host_mutex);
 345         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 346                 hlist_for_each_entry(host, pos, chain, h_hash) {
 347                         if (host->h_nsmhandle == nsm
 348                          && host->h_nsmstate != new_state) {
 349                                 host->h_nsmstate = new_state;
 350                                 host->h_state++;
 351
 352                                 nlm_get_host(host);
 353                                 mutex_unlock(&nlm_host_mutex);
 354
 355                                 if (host->h_server) {
 356                                         /* We're server for this guy, just ditch
 357                                          * all the locks he held. */
 358                                         nlmsvc_free_host_resources(host);
 359                                 } else {
 360                                         /* He's the server, initiate lock recovery. */
 361                                         nlmclnt_recovery(host);
 362                                 }
 363
 364                                 nlm_release_host(host);
 365                                 goto again;
 366                         }
 367                 }
 368         }
 369
 370         mutex_unlock(&nlm_host_mutex);
 371 }
 372
 373 /*
 374  * Shut down the hosts module.
 375  * Note that this routine is called only at server shutdown time.
 376  */
 377 void
 378 nlm_shutdown_hosts(void)
 379 {
 380         struct hlist_head *chain;
 381         struct hlist_node *pos;
 382         struct nlm_host *host;
 383
 384         dprintk("lockd: shutting down host module\n");
 385         mutex_lock(&nlm_host_mutex);
 386
 387         /* First, make all hosts eligible for gc */
 388         dprintk("lockd: nuking all hosts...\n");
 389         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 390                 hlist_for_each_entry(host, pos, chain, h_hash) {
 391                         host->h_expires = jiffies - 1;
 392                         if (host->h_rpcclnt) {
 393                                 rpc_shutdown_client(host->h_rpcclnt);
 394                                 host->h_rpcclnt = NULL;
 395                         }
 396                 }
 397         }
 398
 399         /* Then, perform a garbage collection pass */
 400         nlm_gc_hosts();
 401         mutex_unlock(&nlm_host_mutex);
 402
 403         /* complain if any hosts are left */
 404         if (nrhosts) {
 405                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 406                 dprintk("lockd: %d hosts left:\n", nrhosts);
 407                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 408                         hlist_for_each_entry(host, pos, chain, h_hash) {
 409                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 410                                         host->h_name, atomic_read(&host->h_count),
 411                                         host->h_inuse, host->h_expires);
 412                         }
 413                 }
 414         }
 415 }
 416
 417 /*
 418  * Garbage collect any unused NLM hosts.
 419  * This GC combines reference counting for async operations with
 420  * mark & sweep for resources held by remote clients.
 421  */
 422 static void
 423 nlm_gc_hosts(void)
 424 {
 425         struct hlist_head *chain;
 426         struct hlist_node *pos, *next;
 427         struct nlm_host *host;
 428
 429         dprintk("lockd: host garbage collection\n");
 430         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 431                 hlist_for_each_entry(host, pos, chain, h_hash)
 432                         host->h_inuse = 0;
 433         }
 434
 435         /* Mark all hosts that hold locks, blocks or shares */
 436         nlmsvc_mark_resources();
 437
 438         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 439                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 440                         if (atomic_read(&host->h_count) || host->h_inuse
 441                          || time_before(jiffies, host->h_expires)) {
 442                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 443                                         host->h_name, atomic_read(&host->h_count),
 444                                         host->h_inuse, host->h_expires);
 445                                 continue;
 446                         }
 447                         dprintk("lockd: delete host %s\n", host->h_name);
 448                         hlist_del_init(&host->h_hash);
 449
 450                         nlm_destroy_host(host);
 451                         nrhosts--;
 452                 }
 453         }
 454
 455         next_gc = jiffies + NLM_HOST_COLLECT;
 456 }
 457
 458
 459 /*
 460  * Manage NSM handles
 461  */
 462 static LIST_HEAD(nsm_handles);
 463 static DEFINE_MUTEX(nsm_mutex);
 464
 465 static struct nsm_handle *
 466 __nsm_find(const struct sockaddr_in *sin,
 467                 const char *hostname, unsigned int hostname_len,
 468                 int create)
 469 {
 470         struct nsm_handle *nsm = NULL;
 471         struct list_head *pos;
 472
 473         if (!sin)
 474                 return NULL;
 475
 476         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 477                 if (printk_ratelimit()) {
 478                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 479                                             "in NFS lock request\n",
 480                                 hostname_len, hostname);
 481                 }
 482                 return NULL;
 483         }
 484
 485         mutex_lock(&nsm_mutex);
 486         list_for_each(pos, &nsm_handles) {
 487                 nsm = list_entry(pos, struct nsm_handle, sm_link);
 488
 489                 if (hostname && nsm_use_hostnames) {
 490                         if (strlen(nsm->sm_name) != hostname_len
 491                          || memcmp(nsm->sm_name, hostname, hostname_len))
 492                                 continue;
 493                 } else if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 494                         continue;
 495                 atomic_inc(&nsm->sm_count);
 496                 goto out;
 497         }
 498
 499         if (!create) {
 500                 nsm = NULL;
 501                 goto out;
 502         }
 503
 504         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 505         if (nsm != NULL) {
 506                 nsm->sm_addr = *sin;
 507                 nsm->sm_name = (char *) (nsm + 1);
 508                 memcpy(nsm->sm_name, hostname, hostname_len);
 509                 nsm->sm_name[hostname_len] = '\0';
 510                 atomic_set(&nsm->sm_count, 1);
 511
 512                 list_add(&nsm->sm_link, &nsm_handles);
 513         }
 514
 515 out:
 516         mutex_unlock(&nsm_mutex);
 517         return nsm;
 518 }
 519
 520 static struct nsm_handle *
 521 nsm_find(const struct sockaddr_in *sin, const char *hostname,
 522          unsigned int hostname_len)
 523 {
 524         return __nsm_find(sin, hostname, hostname_len, 1);
 525 }
 526
 527 /*
 528  * Release an NSM handle
 529  */
 530 void
 531 nsm_release(struct nsm_handle *nsm)
 532 {
 533         if (!nsm)
 534                 return;
 535         if (atomic_dec_and_test(&nsm->sm_count)) {
 536                 mutex_lock(&nsm_mutex);
 537                 if (atomic_read(&nsm->sm_count) == 0) {
 538                         list_del(&nsm->sm_link);
 539                         kfree(nsm);
 540                 }
 541                 mutex_unlock(&nsm_mutex);
 542         }
 543 }