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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/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/in.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/sunrpc/svc.h>
  17 #include <linux/lockd/lockd.h>
  18 #include <linux/lockd/sm_inter.h>
  19 #include <linux/mutex.h>
  20
  21
  22 #define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
  23 #define NLM_HOST_MAX            64
  24 #define NLM_HOST_NRHASH         32
  25 #define NLM_ADDRHASH(addr)      (ntohl(addr) & (NLM_HOST_NRHASH-1))
  26 #define NLM_HOST_REBIND         (60 * HZ)
  27 #define NLM_HOST_EXPIRE         ((nrhosts > NLM_HOST_MAX)? 300 * HZ : 120 * HZ)
  28 #define NLM_HOST_COLLECT        ((nrhosts > NLM_HOST_MAX)? 120 * HZ :  60 * HZ)
  29
  30 static struct hlist_head        nlm_hosts[NLM_HOST_NRHASH];
  31 static unsigned long            next_gc;
  32 static int                      nrhosts;
  33 static DEFINE_MUTEX(nlm_host_mutex);
  34
  35
  36 static void                     nlm_gc_hosts(void);
  37 static struct nsm_handle *      __nsm_find(const struct sockaddr_in *,
  38                                         const char *, int, int);
  39
  40 /*
  41  * Find an NLM server handle in the cache. If there is none, create it.
  42  */
  43 struct nlm_host *
  44 nlmclnt_lookup_host(const struct sockaddr_in *sin, int proto, int version,
  45                         const char *hostname, int hostname_len)
  46 {
  47         return nlm_lookup_host(0, sin, proto, version,
  48                                hostname, hostname_len);
  49 }
  50
  51 /*
  52  * Find an NLM client handle in the cache. If there is none, create it.
  53  */
  54 struct nlm_host *
  55 nlmsvc_lookup_host(struct svc_rqst *rqstp,
  56                         const char *hostname, int hostname_len)
  57 {
  58         return nlm_lookup_host(1, &rqstp->rq_addr,
  59                                rqstp->rq_prot, rqstp->rq_vers,
  60                                hostname, hostname_len);
  61 }
  62
  63 /*
  64  * Common host lookup routine for server & client
  65  */
  66 struct nlm_host *
  67 nlm_lookup_host(int server, const struct sockaddr_in *sin,
  68                                         int proto, int version,
  69                                         const char *hostname,
  70                                         int hostname_len)
  71 {
  72         struct hlist_head *chain;
  73         struct hlist_node *pos;
  74         struct nlm_host *host;
  75         struct nsm_handle *nsm = NULL;
  76         int             hash;
  77
  78         dprintk("lockd: nlm_lookup_host(%u.%u.%u.%u, p=%d, v=%d, my role=%s, name=%.*s)\n",
  79                         NIPQUAD(sin->sin_addr.s_addr), proto, version,
  80                         server? "server" : "client",
  81                         hostname_len,
  82                         hostname? hostname : "<none>");
  83
  84
  85         hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
  86
  87         /* Lock hash table */
  88         mutex_lock(&nlm_host_mutex);
  89
  90         if (time_after_eq(jiffies, next_gc))
  91                 nlm_gc_hosts();
  92
  93         /* We may keep several nlm_host objects for a peer, because each
  94          * nlm_host is identified by
  95          * (address, protocol, version, server/client)
  96          * We could probably simplify this a little by putting all those
  97          * different NLM rpc_clients into one single nlm_host object.
  98          * This would allow us to have one nlm_host per address.
  99          */
 100         chain = &nlm_hosts[hash];
 101         hlist_for_each_entry(host, pos, chain, h_hash) {
 102                 if (!nlm_cmp_addr(&host->h_addr, sin))
 103                         continue;
 104
 105                 /* See if we have an NSM handle for this client */
 106                 if (!nsm)
 107                         nsm = host->h_nsmhandle;
 108
 109                 if (host->h_proto != proto)
 110                         continue;
 111                 if (host->h_version != version)
 112                         continue;
 113                 if (host->h_server != server)
 114                         continue;
 115
 116                 /* Move to head of hash chain. */
 117                 hlist_del(&host->h_hash);
 118                 hlist_add_head(&host->h_hash, chain);
 119
 120                 nlm_get_host(host);
 121                 goto out;
 122         }
 123         if (nsm)
 124                 atomic_inc(&nsm->sm_count);
 125
 126         host = NULL;
 127
 128         /* Sadly, the host isn't in our hash table yet. See if
 129          * we have an NSM handle for it. If not, create one.
 130          */
 131         if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
 132                 goto out;
 133
 134         host = kzalloc(sizeof(*host), GFP_KERNEL);
 135         if (!host) {
 136                 nsm_release(nsm);
 137                 goto out;
 138         }
 139         host->h_name       = nsm->sm_name;
 140         host->h_addr       = *sin;
 141         host->h_addr.sin_port = 0;      /* ouch! */
 142         host->h_version    = version;
 143         host->h_proto      = proto;
 144         host->h_rpcclnt    = NULL;
 145         mutex_init(&host->h_mutex);
 146         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 147         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 148         atomic_set(&host->h_count, 1);
 149         init_waitqueue_head(&host->h_gracewait);
 150         init_rwsem(&host->h_rwsem);
 151         host->h_state      = 0;                 /* pseudo NSM state */
 152         host->h_nsmstate   = 0;                 /* real NSM state */
 153         host->h_nsmhandle  = nsm;
 154         host->h_server     = server;
 155         hlist_add_head(&host->h_hash, chain);
 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
 161         if (++nrhosts > NLM_HOST_MAX)
 162                 next_gc = 0;
 163
 164 out:
 165         mutex_unlock(&nlm_host_mutex);
 166         return host;
 167 }
 168
 169 /*
 170  * Destroy a host
 171  */
 172 static void
 173 nlm_destroy_host(struct nlm_host *host)
 174 {
 175         struct rpc_clnt *clnt;
 176
 177         BUG_ON(!list_empty(&host->h_lockowners));
 178         BUG_ON(atomic_read(&host->h_count));
 179
 180         /*
 181          * Release NSM handle and unmonitor host.
 182          */
 183         nsm_unmonitor(host);
 184
 185         if ((clnt = host->h_rpcclnt) != NULL) {
 186                 if (atomic_read(&clnt->cl_users)) {
 187                         printk(KERN_WARNING
 188                                 "lockd: active RPC handle\n");
 189                         clnt->cl_dead = 1;
 190                 } else {
 191                         rpc_destroy_client(host->h_rpcclnt);
 192                 }
 193         }
 194         kfree(host);
 195 }
 196
 197 /*
 198  * Create the NLM RPC client for an NLM peer
 199  */
 200 struct rpc_clnt *
 201 nlm_bind_host(struct nlm_host *host)
 202 {
 203         struct rpc_clnt *clnt;
 204
 205         dprintk("lockd: nlm_bind_host(%08x)\n",
 206                         (unsigned)ntohl(host->h_addr.sin_addr.s_addr));
 207
 208         /* Lock host handle */
 209         mutex_lock(&host->h_mutex);
 210
 211         /* If we've already created an RPC client, check whether
 212          * RPC rebind is required
 213          */
 214         if ((clnt = host->h_rpcclnt) != NULL) {
 215                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 216                         rpc_force_rebind(clnt);
 217                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 218                         dprintk("lockd: next rebind in %ld jiffies\n",
 219                                         host->h_nextrebind - jiffies);
 220                 }
 221         } else {
 222                 unsigned long increment = nlmsvc_timeout * HZ;
 223                 struct rpc_timeout timeparms = {
 224                         .to_initval     = increment,
 225                         .to_increment   = increment,
 226                         .to_maxval      = increment * 6UL,
 227                         .to_retries     = 5U,
 228                 };
 229                 struct rpc_create_args args = {
 230                         .protocol       = host->h_proto,
 231                         .address        = (struct sockaddr *)&host->h_addr,
 232                         .addrsize       = sizeof(host->h_addr),
 233                         .timeout        = &timeparms,
 234                         .servername     = host->h_name,
 235                         .program        = &nlm_program,
 236                         .version        = host->h_version,
 237                         .authflavor     = RPC_AUTH_UNIX,
 238                         .flags          = (RPC_CLNT_CREATE_HARDRTRY |
 239                                            RPC_CLNT_CREATE_AUTOBIND),
 240                 };
 241
 242                 clnt = rpc_create(&args);
 243                 if (!IS_ERR(clnt))
 244                         host->h_rpcclnt = clnt;
 245                 else {
 246                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 247                         clnt = NULL;
 248                 }
 249         }
 250
 251         mutex_unlock(&host->h_mutex);
 252         return clnt;
 253 }
 254
 255 /*
 256  * Force a portmap lookup of the remote lockd port
 257  */
 258 void
 259 nlm_rebind_host(struct nlm_host *host)
 260 {
 261         dprintk("lockd: rebind host %s\n", host->h_name);
 262         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 263                 rpc_force_rebind(host->h_rpcclnt);
 264                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 265         }
 266 }
 267
 268 /*
 269  * Increment NLM host count
 270  */
 271 struct nlm_host * nlm_get_host(struct nlm_host *host)
 272 {
 273         if (host) {
 274                 dprintk("lockd: get host %s\n", host->h_name);
 275                 atomic_inc(&host->h_count);
 276                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 277         }
 278         return host;
 279 }
 280
 281 /*
 282  * Release NLM host after use
 283  */
 284 void nlm_release_host(struct nlm_host *host)
 285 {
 286         if (host != NULL) {
 287                 dprintk("lockd: release host %s\n", host->h_name);
 288                 BUG_ON(atomic_read(&host->h_count) < 0);
 289                 if (atomic_dec_and_test(&host->h_count)) {
 290                         BUG_ON(!list_empty(&host->h_lockowners));
 291                         BUG_ON(!list_empty(&host->h_granted));
 292                         BUG_ON(!list_empty(&host->h_reclaim));
 293                 }
 294         }
 295 }
 296
 297 /*
 298  * We were notified that the host indicated by address &sin
 299  * has rebooted.
 300  * Release all resources held by that peer.
 301  */
 302 void nlm_host_rebooted(const struct sockaddr_in *sin,
 303                                 const char *hostname, int hostname_len,
 304                                 u32 new_state)
 305 {
 306         struct hlist_head *chain;
 307         struct hlist_node *pos;
 308         struct nsm_handle *nsm;
 309         struct nlm_host *host;
 310
 311         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 312                         hostname, NIPQUAD(sin->sin_addr));
 313
 314         /* Find the NSM handle for this peer */
 315         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 316                 return;
 317
 318         /* When reclaiming locks on this peer, make sure that
 319          * we set up a new notification */
 320         nsm->sm_monitored = 0;
 321
 322         /* Mark all hosts tied to this NSM state as having rebooted.
 323          * We run the loop repeatedly, because we drop the host table
 324          * lock for this.
 325          * To avoid processing a host several times, we match the nsmstate.
 326          */
 327 again:  mutex_lock(&nlm_host_mutex);
 328         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 329                 hlist_for_each_entry(host, pos, chain, h_hash) {
 330                         if (host->h_nsmhandle == nsm
 331                          && host->h_nsmstate != new_state) {
 332                                 host->h_nsmstate = new_state;
 333                                 host->h_state++;
 334
 335                                 nlm_get_host(host);
 336                                 mutex_unlock(&nlm_host_mutex);
 337
 338                                 if (host->h_server) {
 339                                         /* We're server for this guy, just ditch
 340                                          * all the locks he held. */
 341                                         nlmsvc_free_host_resources(host);
 342                                 } else {
 343                                         /* He's the server, initiate lock recovery. */
 344                                         nlmclnt_recovery(host);
 345                                 }
 346
 347                                 nlm_release_host(host);
 348                                 goto again;
 349                         }
 350                 }
 351         }
 352
 353         mutex_unlock(&nlm_host_mutex);
 354 }
 355
 356 /*
 357  * Shut down the hosts module.
 358  * Note that this routine is called only at server shutdown time.
 359  */
 360 void
 361 nlm_shutdown_hosts(void)
 362 {
 363         struct hlist_head *chain;
 364         struct hlist_node *pos;
 365         struct nlm_host *host;
 366
 367         dprintk("lockd: shutting down host module\n");
 368         mutex_lock(&nlm_host_mutex);
 369
 370         /* First, make all hosts eligible for gc */
 371         dprintk("lockd: nuking all hosts...\n");
 372         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 373                 hlist_for_each_entry(host, pos, chain, h_hash)
 374                         host->h_expires = jiffies - 1;
 375         }
 376
 377         /* Then, perform a garbage collection pass */
 378         nlm_gc_hosts();
 379         mutex_unlock(&nlm_host_mutex);
 380
 381         /* complain if any hosts are left */
 382         if (nrhosts) {
 383                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 384                 dprintk("lockd: %d hosts left:\n", nrhosts);
 385                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 386                         hlist_for_each_entry(host, pos, chain, h_hash) {
 387                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 388                                         host->h_name, atomic_read(&host->h_count),
 389                                         host->h_inuse, host->h_expires);
 390                         }
 391                 }
 392         }
 393 }
 394
 395 /*
 396  * Garbage collect any unused NLM hosts.
 397  * This GC combines reference counting for async operations with
 398  * mark & sweep for resources held by remote clients.
 399  */
 400 static void
 401 nlm_gc_hosts(void)
 402 {
 403         struct hlist_head *chain;
 404         struct hlist_node *pos, *next;
 405         struct nlm_host *host;
 406
 407         dprintk("lockd: host garbage collection\n");
 408         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 409                 hlist_for_each_entry(host, pos, chain, h_hash)
 410                         host->h_inuse = 0;
 411         }
 412
 413         /* Mark all hosts that hold locks, blocks or shares */
 414         nlmsvc_mark_resources();
 415
 416         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 417                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 418                         if (atomic_read(&host->h_count) || host->h_inuse
 419                          || time_before(jiffies, host->h_expires)) {
 420                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 421                                         host->h_name, atomic_read(&host->h_count),
 422                                         host->h_inuse, host->h_expires);
 423                                 continue;
 424                         }
 425                         dprintk("lockd: delete host %s\n", host->h_name);
 426                         hlist_del_init(&host->h_hash);
 427
 428                         nlm_destroy_host(host);
 429                         nrhosts--;
 430                 }
 431         }
 432
 433         next_gc = jiffies + NLM_HOST_COLLECT;
 434 }
 435
 436
 437 /*
 438  * Manage NSM handles
 439  */
 440 static LIST_HEAD(nsm_handles);
 441 static DEFINE_MUTEX(nsm_mutex);
 442
 443 static struct nsm_handle *
 444 __nsm_find(const struct sockaddr_in *sin,
 445                 const char *hostname, int hostname_len,
 446                 int create)
 447 {
 448         struct nsm_handle *nsm = NULL;
 449         struct list_head *pos;
 450
 451         if (!sin)
 452                 return NULL;
 453
 454         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 455                 if (printk_ratelimit()) {
 456                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 457                                             "in NFS lock request\n",
 458                                 hostname_len, hostname);
 459                 }
 460                 return NULL;
 461         }
 462
 463         mutex_lock(&nsm_mutex);
 464         list_for_each(pos, &nsm_handles) {
 465                 nsm = list_entry(pos, struct nsm_handle, sm_link);
 466
 467                 if (hostname && nsm_use_hostnames) {
 468                         if (strlen(nsm->sm_name) != hostname_len
 469                          || memcmp(nsm->sm_name, hostname, hostname_len))
 470                                 continue;
 471                 } else if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 472                         continue;
 473                 atomic_inc(&nsm->sm_count);
 474                 goto out;
 475         }
 476
 477         if (!create) {
 478                 nsm = NULL;
 479                 goto out;
 480         }
 481
 482         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 483         if (nsm != NULL) {
 484                 nsm->sm_addr = *sin;
 485                 nsm->sm_name = (char *) (nsm + 1);
 486                 memcpy(nsm->sm_name, hostname, hostname_len);
 487                 nsm->sm_name[hostname_len] = '\0';
 488                 atomic_set(&nsm->sm_count, 1);
 489
 490                 list_add(&nsm->sm_link, &nsm_handles);
 491         }
 492
 493 out:
 494         mutex_unlock(&nsm_mutex);
 495         return nsm;
 496 }
 497
 498 struct nsm_handle *
 499 nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)
 500 {
 501         return __nsm_find(sin, hostname, hostname_len, 1);
 502 }
 503
 504 /*
 505  * Release an NSM handle
 506  */
 507 void
 508 nsm_release(struct nsm_handle *nsm)
 509 {
 510         if (!nsm)
 511                 return;
 512         if (atomic_dec_and_test(&nsm->sm_count)) {
 513                 mutex_lock(&nsm_mutex);
 514                 if (atomic_read(&nsm->sm_count) == 0) {
 515                         list_del(&nsm->sm_link);
 516                         kfree(nsm);
 517                 }
 518                 mutex_unlock(&nsm_mutex);
 519         }
 520 }