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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
 107         /*
 108          * The host wasn't in our hash table.  If we don't
 109          * have an NSM handle for it yet, create one.
 110          */
 111         if (nsm)
 112                 atomic_inc(&nsm->sm_count);
 113         else {
 114                 host = NULL;
 115                 nsm = nsm_find(sin, hostname, hostname_len);
 116                 if (!nsm)
 117                         goto out;
 118         }
 119
 120         host = kzalloc(sizeof(*host), GFP_KERNEL);
 121         if (!host) {
 122                 nsm_release(nsm);
 123                 goto out;
 124         }
 125         host->h_name       = nsm->sm_name;
 126         host->h_addr       = *sin;
 127         host->h_addr.sin_port = 0;      /* ouch! */
 128         host->h_saddr      = *ssin;
 129         host->h_version    = version;
 130         host->h_proto      = proto;
 131         host->h_rpcclnt    = NULL;
 132         mutex_init(&host->h_mutex);
 133         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 134         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 135         atomic_set(&host->h_count, 1);
 136         init_waitqueue_head(&host->h_gracewait);
 137         init_rwsem(&host->h_rwsem);
 138         host->h_state      = 0;                 /* pseudo NSM state */
 139         host->h_nsmstate   = 0;                 /* real NSM state */
 140         host->h_nsmhandle  = nsm;
 141         host->h_server     = server;
 142         hlist_add_head(&host->h_hash, chain);
 143         INIT_LIST_HEAD(&host->h_lockowners);
 144         spin_lock_init(&host->h_lock);
 145         INIT_LIST_HEAD(&host->h_granted);
 146         INIT_LIST_HEAD(&host->h_reclaim);
 147
 148         nrhosts++;
 149 out:
 150         mutex_unlock(&nlm_host_mutex);
 151         return host;
 152 }
 153
 154 /*
 155  * Destroy a host
 156  */
 157 static void
 158 nlm_destroy_host(struct nlm_host *host)
 159 {
 160         struct rpc_clnt *clnt;
 161
 162         BUG_ON(!list_empty(&host->h_lockowners));
 163         BUG_ON(atomic_read(&host->h_count));
 164
 165         /*
 166          * Release NSM handle and unmonitor host.
 167          */
 168         nsm_unmonitor(host);
 169
 170         clnt = host->h_rpcclnt;
 171         if (clnt != NULL)
 172                 rpc_shutdown_client(clnt);
 173         kfree(host);
 174 }
 175
 176 /*
 177  * Find an NLM server handle in the cache. If there is none, create it.
 178  */
 179 struct nlm_host *nlmclnt_lookup_host(const struct sockaddr_in *sin,
 180                                      int proto, u32 version,
 181                                      const char *hostname,
 182                                      unsigned int hostname_len)
 183 {
 184         struct sockaddr_in ssin = {0};
 185
 186         return nlm_lookup_host(0, sin, proto, version,
 187                                hostname, hostname_len, &ssin);
 188 }
 189
 190 /*
 191  * Find an NLM client handle in the cache. If there is none, create it.
 192  */
 193 struct nlm_host *
 194 nlmsvc_lookup_host(struct svc_rqst *rqstp,
 195                         const char *hostname, unsigned int hostname_len)
 196 {
 197         struct sockaddr_in ssin = {0};
 198
 199         ssin.sin_addr = rqstp->rq_daddr.addr;
 200         return nlm_lookup_host(1, svc_addr_in(rqstp),
 201                                rqstp->rq_prot, rqstp->rq_vers,
 202                                hostname, hostname_len, &ssin);
 203 }
 204
 205 /*
 206  * Create the NLM RPC client for an NLM peer
 207  */
 208 struct rpc_clnt *
 209 nlm_bind_host(struct nlm_host *host)
 210 {
 211         struct rpc_clnt *clnt;
 212
 213         dprintk("lockd: nlm_bind_host("NIPQUAD_FMT"->"NIPQUAD_FMT")\n",
 214                         NIPQUAD(host->h_saddr.sin_addr),
 215                         NIPQUAD(host->h_addr.sin_addr));
 216
 217         /* Lock host handle */
 218         mutex_lock(&host->h_mutex);
 219
 220         /* If we've already created an RPC client, check whether
 221          * RPC rebind is required
 222          */
 223         if ((clnt = host->h_rpcclnt) != NULL) {
 224                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 225                         rpc_force_rebind(clnt);
 226                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 227                         dprintk("lockd: next rebind in %ld jiffies\n",
 228                                         host->h_nextrebind - jiffies);
 229                 }
 230         } else {
 231                 unsigned long increment = nlmsvc_timeout;
 232                 struct rpc_timeout timeparms = {
 233                         .to_initval     = increment,
 234                         .to_increment   = increment,
 235                         .to_maxval      = increment * 6UL,
 236                         .to_retries     = 5U,
 237                 };
 238                 struct rpc_create_args args = {
 239                         .protocol       = host->h_proto,
 240                         .address        = (struct sockaddr *)&host->h_addr,
 241                         .addrsize       = sizeof(host->h_addr),
 242                         .saddress       = (struct sockaddr *)&host->h_saddr,
 243                         .timeout        = &timeparms,
 244                         .servername     = host->h_name,
 245                         .program        = &nlm_program,
 246                         .version        = host->h_version,
 247                         .authflavor     = RPC_AUTH_UNIX,
 248                         .flags          = (RPC_CLNT_CREATE_NOPING |
 249                                            RPC_CLNT_CREATE_AUTOBIND),
 250                 };
 251
 252                 /*
 253                  * lockd retries server side blocks automatically so we want
 254                  * those to be soft RPC calls. Client side calls need to be
 255                  * hard RPC tasks.
 256                  */
 257                 if (!host->h_server)
 258                         args.flags |= RPC_CLNT_CREATE_HARDRTRY;
 259
 260                 clnt = rpc_create(&args);
 261                 if (!IS_ERR(clnt))
 262                         host->h_rpcclnt = clnt;
 263                 else {
 264                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 265                         clnt = NULL;
 266                 }
 267         }
 268
 269         mutex_unlock(&host->h_mutex);
 270         return clnt;
 271 }
 272
 273 /*
 274  * Force a portmap lookup of the remote lockd port
 275  */
 276 void
 277 nlm_rebind_host(struct nlm_host *host)
 278 {
 279         dprintk("lockd: rebind host %s\n", host->h_name);
 280         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 281                 rpc_force_rebind(host->h_rpcclnt);
 282                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 283         }
 284 }
 285
 286 /*
 287  * Increment NLM host count
 288  */
 289 struct nlm_host * nlm_get_host(struct nlm_host *host)
 290 {
 291         if (host) {
 292                 dprintk("lockd: get host %s\n", host->h_name);
 293                 atomic_inc(&host->h_count);
 294                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 295         }
 296         return host;
 297 }
 298
 299 /*
 300  * Release NLM host after use
 301  */
 302 void nlm_release_host(struct nlm_host *host)
 303 {
 304         if (host != NULL) {
 305                 dprintk("lockd: release host %s\n", host->h_name);
 306                 BUG_ON(atomic_read(&host->h_count) < 0);
 307                 if (atomic_dec_and_test(&host->h_count)) {
 308                         BUG_ON(!list_empty(&host->h_lockowners));
 309                         BUG_ON(!list_empty(&host->h_granted));
 310                         BUG_ON(!list_empty(&host->h_reclaim));
 311                 }
 312         }
 313 }
 314
 315 /*
 316  * We were notified that the host indicated by address &sin
 317  * has rebooted.
 318  * Release all resources held by that peer.
 319  */
 320 void nlm_host_rebooted(const struct sockaddr_in *sin,
 321                                 const char *hostname,
 322                                 unsigned int hostname_len,
 323                                 u32 new_state)
 324 {
 325         struct hlist_head *chain;
 326         struct hlist_node *pos;
 327         struct nsm_handle *nsm;
 328         struct nlm_host *host;
 329
 330         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 331                         hostname, NIPQUAD(sin->sin_addr));
 332
 333         /* Find the NSM handle for this peer */
 334         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 335                 return;
 336
 337         /* When reclaiming locks on this peer, make sure that
 338          * we set up a new notification */
 339         nsm->sm_monitored = 0;
 340
 341         /* Mark all hosts tied to this NSM state as having rebooted.
 342          * We run the loop repeatedly, because we drop the host table
 343          * lock for this.
 344          * To avoid processing a host several times, we match the nsmstate.
 345          */
 346 again:  mutex_lock(&nlm_host_mutex);
 347         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 348                 hlist_for_each_entry(host, pos, chain, h_hash) {
 349                         if (host->h_nsmhandle == nsm
 350                          && host->h_nsmstate != new_state) {
 351                                 host->h_nsmstate = new_state;
 352                                 host->h_state++;
 353
 354                                 nlm_get_host(host);
 355                                 mutex_unlock(&nlm_host_mutex);
 356
 357                                 if (host->h_server) {
 358                                         /* We're server for this guy, just ditch
 359                                          * all the locks he held. */
 360                                         nlmsvc_free_host_resources(host);
 361                                 } else {
 362                                         /* He's the server, initiate lock recovery. */
 363                                         nlmclnt_recovery(host);
 364                                 }
 365
 366                                 nlm_release_host(host);
 367                                 goto again;
 368                         }
 369                 }
 370         }
 371
 372         mutex_unlock(&nlm_host_mutex);
 373 }
 374
 375 /*
 376  * Shut down the hosts module.
 377  * Note that this routine is called only at server shutdown time.
 378  */
 379 void
 380 nlm_shutdown_hosts(void)
 381 {
 382         struct hlist_head *chain;
 383         struct hlist_node *pos;
 384         struct nlm_host *host;
 385
 386         dprintk("lockd: shutting down host module\n");
 387         mutex_lock(&nlm_host_mutex);
 388
 389         /* First, make all hosts eligible for gc */
 390         dprintk("lockd: nuking all hosts...\n");
 391         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 392                 hlist_for_each_entry(host, pos, chain, h_hash) {
 393                         host->h_expires = jiffies - 1;
 394                         if (host->h_rpcclnt) {
 395                                 rpc_shutdown_client(host->h_rpcclnt);
 396                                 host->h_rpcclnt = NULL;
 397                         }
 398                 }
 399         }
 400
 401         /* Then, perform a garbage collection pass */
 402         nlm_gc_hosts();
 403         mutex_unlock(&nlm_host_mutex);
 404
 405         /* complain if any hosts are left */
 406         if (nrhosts) {
 407                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 408                 dprintk("lockd: %d hosts left:\n", nrhosts);
 409                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 410                         hlist_for_each_entry(host, pos, chain, h_hash) {
 411                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 412                                         host->h_name, atomic_read(&host->h_count),
 413                                         host->h_inuse, host->h_expires);
 414                         }
 415                 }
 416         }
 417 }
 418
 419 /*
 420  * Garbage collect any unused NLM hosts.
 421  * This GC combines reference counting for async operations with
 422  * mark & sweep for resources held by remote clients.
 423  */
 424 static void
 425 nlm_gc_hosts(void)
 426 {
 427         struct hlist_head *chain;
 428         struct hlist_node *pos, *next;
 429         struct nlm_host *host;
 430
 431         dprintk("lockd: host garbage collection\n");
 432         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 433                 hlist_for_each_entry(host, pos, chain, h_hash)
 434                         host->h_inuse = 0;
 435         }
 436
 437         /* Mark all hosts that hold locks, blocks or shares */
 438         nlmsvc_mark_resources();
 439
 440         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 441                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 442                         if (atomic_read(&host->h_count) || host->h_inuse
 443                          || time_before(jiffies, host->h_expires)) {
 444                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 445                                         host->h_name, atomic_read(&host->h_count),
 446                                         host->h_inuse, host->h_expires);
 447                                 continue;
 448                         }
 449                         dprintk("lockd: delete host %s\n", host->h_name);
 450                         hlist_del_init(&host->h_hash);
 451
 452                         nlm_destroy_host(host);
 453                         nrhosts--;
 454                 }
 455         }
 456
 457         next_gc = jiffies + NLM_HOST_COLLECT;
 458 }
 459
 460
 461 /*
 462  * Manage NSM handles
 463  */
 464 static LIST_HEAD(nsm_handles);
 465 static DEFINE_SPINLOCK(nsm_lock);
 466
 467 static struct nsm_handle *
 468 __nsm_find(const struct sockaddr_in *sin,
 469                 const char *hostname, unsigned int hostname_len,
 470                 int create)
 471 {
 472         struct nsm_handle *nsm = NULL;
 473         struct nsm_handle *pos;
 474
 475         if (!sin)
 476                 return NULL;
 477
 478         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 479                 if (printk_ratelimit()) {
 480                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 481                                             "in NFS lock request\n",
 482                                 hostname_len, hostname);
 483                 }
 484                 return NULL;
 485         }
 486
 487 retry:
 488         spin_lock(&nsm_lock);
 489         list_for_each_entry(pos, &nsm_handles, sm_link) {
 490
 491                 if (hostname && nsm_use_hostnames) {
 492                         if (strlen(pos->sm_name) != hostname_len
 493                          || memcmp(pos->sm_name, hostname, hostname_len))
 494                                 continue;
 495                 } else if (!nlm_cmp_addr(&pos->sm_addr, sin))
 496                         continue;
 497                 atomic_inc(&pos->sm_count);
 498                 kfree(nsm);
 499                 nsm = pos;
 500                 goto found;
 501         }
 502         if (nsm) {
 503                 list_add(&nsm->sm_link, &nsm_handles);
 504                 goto found;
 505         }
 506         spin_unlock(&nsm_lock);
 507
 508         if (!create)
 509                 return NULL;
 510
 511         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 512         if (nsm == NULL)
 513                 return NULL;
 514
 515         nsm->sm_addr = *sin;
 516         nsm->sm_name = (char *) (nsm + 1);
 517         memcpy(nsm->sm_name, hostname, hostname_len);
 518         nsm->sm_name[hostname_len] = '\0';
 519         atomic_set(&nsm->sm_count, 1);
 520         goto retry;
 521
 522 found:
 523         spin_unlock(&nsm_lock);
 524         return nsm;
 525 }
 526
 527 static struct nsm_handle *
 528 nsm_find(const struct sockaddr_in *sin, const char *hostname,
 529          unsigned int hostname_len)
 530 {
 531         return __nsm_find(sin, hostname, hostname_len, 1);
 532 }
 533
 534 /*
 535  * Release an NSM handle
 536  */
 537 void
 538 nsm_release(struct nsm_handle *nsm)
 539 {
 540         if (!nsm)
 541                 return;
 542         if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
 543                 list_del(&nsm->sm_link);
 544                 spin_unlock(&nsm_lock);
 545                 kfree(nsm);
 546         }
 547 }