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/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 *, int, int);
  38 static struct nsm_handle *      nsm_find(const struct sockaddr_in *sin,
  39                                          const char *hostname,
  40                                          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,
  48                                         const char *hostname,
  49                                         int hostname_len)
  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(%u.%u.%u.%u, p=%d, v=%d, my role=%s, name=%.*s)\n",
  58                         NIPQUAD(sin->sin_addr.s_addr), proto, version,
  59                         server? "server" : "client",
  60                         hostname_len,
  61                         hostname? hostname : "<none>");
  62
  63
  64         hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
  65
  66         /* Lock hash table */
  67         mutex_lock(&nlm_host_mutex);
  68
  69         if (time_after_eq(jiffies, next_gc))
  70                 nlm_gc_hosts();
  71
  72         /* We may keep several nlm_host objects for a peer, because each
  73          * nlm_host is identified by
  74          * (address, protocol, version, server/client)
  75          * We could probably simplify this a little by putting all those
  76          * different NLM rpc_clients into one single nlm_host object.
  77          * This would allow us to have one nlm_host per address.
  78          */
  79         chain = &nlm_hosts[hash];
  80         hlist_for_each_entry(host, pos, chain, h_hash) {
  81                 if (!nlm_cmp_addr(&host->h_addr, sin))
  82                         continue;
  83
  84                 /* See if we have an NSM handle for this client */
  85                 if (!nsm)
  86                         nsm = host->h_nsmhandle;
  87
  88                 if (host->h_proto != proto)
  89                         continue;
  90                 if (host->h_version != version)
  91                         continue;
  92                 if (host->h_server != server)
  93                         continue;
  94
  95                 /* Move to head of hash chain. */
  96                 hlist_del(&host->h_hash);
  97                 hlist_add_head(&host->h_hash, chain);
  98
  99                 nlm_get_host(host);
 100                 goto out;
 101         }
 102         if (nsm)
 103                 atomic_inc(&nsm->sm_count);
 104
 105         host = NULL;
 106
 107         /* Sadly, the host isn't in our hash table yet. See if
 108          * we have an NSM handle for it. If not, create one.
 109          */
 110         if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
 111                 goto out;
 112
 113         host = kzalloc(sizeof(*host), GFP_KERNEL);
 114         if (!host) {
 115                 nsm_release(nsm);
 116                 goto out;
 117         }
 118         host->h_name       = nsm->sm_name;
 119         host->h_addr       = *sin;
 120         host->h_addr.sin_port = 0;      /* ouch! */
 121         host->h_version    = version;
 122         host->h_proto      = proto;
 123         host->h_rpcclnt    = NULL;
 124         mutex_init(&host->h_mutex);
 125         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 126         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 127         atomic_set(&host->h_count, 1);
 128         init_waitqueue_head(&host->h_gracewait);
 129         init_rwsem(&host->h_rwsem);
 130         host->h_state      = 0;                 /* pseudo NSM state */
 131         host->h_nsmstate   = 0;                 /* real NSM state */
 132         host->h_nsmhandle  = nsm;
 133         host->h_server     = server;
 134         hlist_add_head(&host->h_hash, chain);
 135         INIT_LIST_HEAD(&host->h_lockowners);
 136         spin_lock_init(&host->h_lock);
 137         INIT_LIST_HEAD(&host->h_granted);
 138         INIT_LIST_HEAD(&host->h_reclaim);
 139
 140         if (++nrhosts > NLM_HOST_MAX)
 141                 next_gc = 0;
 142
 143 out:
 144         mutex_unlock(&nlm_host_mutex);
 145         return host;
 146 }
 147
 148 /*
 149  * Destroy a host
 150  */
 151 static void
 152 nlm_destroy_host(struct nlm_host *host)
 153 {
 154         struct rpc_clnt *clnt;
 155
 156         BUG_ON(!list_empty(&host->h_lockowners));
 157         BUG_ON(atomic_read(&host->h_count));
 158
 159         /*
 160          * Release NSM handle and unmonitor host.
 161          */
 162         nsm_unmonitor(host);
 163
 164         clnt = host->h_rpcclnt;
 165         if (clnt != NULL)
 166                 rpc_shutdown_client(clnt);
 167         kfree(host);
 168 }
 169
 170 /*
 171  * Find an NLM server handle in the cache. If there is none, create it.
 172  */
 173 struct nlm_host *
 174 nlmclnt_lookup_host(const struct sockaddr_in *sin, int proto, int version,
 175                         const char *hostname, int hostname_len)
 176 {
 177         return nlm_lookup_host(0, sin, proto, version,
 178                                hostname, hostname_len);
 179 }
 180
 181 /*
 182  * Find an NLM client handle in the cache. If there is none, create it.
 183  */
 184 struct nlm_host *
 185 nlmsvc_lookup_host(struct svc_rqst *rqstp,
 186                         const char *hostname, int hostname_len)
 187 {
 188         return nlm_lookup_host(1, svc_addr_in(rqstp),
 189                                rqstp->rq_prot, rqstp->rq_vers,
 190                                hostname, hostname_len);
 191 }
 192
 193 /*
 194  * Create the NLM RPC client for an NLM peer
 195  */
 196 struct rpc_clnt *
 197 nlm_bind_host(struct nlm_host *host)
 198 {
 199         struct rpc_clnt *clnt;
 200
 201         dprintk("lockd: nlm_bind_host(%08x)\n",
 202                         (unsigned)ntohl(host->h_addr.sin_addr.s_addr));
 203
 204         /* Lock host handle */
 205         mutex_lock(&host->h_mutex);
 206
 207         /* If we've already created an RPC client, check whether
 208          * RPC rebind is required
 209          */
 210         if ((clnt = host->h_rpcclnt) != NULL) {
 211                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 212                         rpc_force_rebind(clnt);
 213                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 214                         dprintk("lockd: next rebind in %ld jiffies\n",
 215                                         host->h_nextrebind - jiffies);
 216                 }
 217         } else {
 218                 unsigned long increment = nlmsvc_timeout;
 219                 struct rpc_timeout timeparms = {
 220                         .to_initval     = increment,
 221                         .to_increment   = increment,
 222                         .to_maxval      = increment * 6UL,
 223                         .to_retries     = 5U,
 224                 };
 225                 struct rpc_create_args args = {
 226                         .protocol       = host->h_proto,
 227                         .address        = (struct sockaddr *)&host->h_addr,
 228                         .addrsize       = sizeof(host->h_addr),
 229                         .timeout        = &timeparms,
 230                         .servername     = host->h_name,
 231                         .program        = &nlm_program,
 232                         .version        = host->h_version,
 233                         .authflavor     = RPC_AUTH_UNIX,
 234                         .flags          = (RPC_CLNT_CREATE_HARDRTRY |
 235                                            RPC_CLNT_CREATE_AUTOBIND),
 236                 };
 237
 238                 clnt = rpc_create(&args);
 239                 if (!IS_ERR(clnt))
 240                         host->h_rpcclnt = clnt;
 241                 else {
 242                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 243                         clnt = NULL;
 244                 }
 245         }
 246
 247         mutex_unlock(&host->h_mutex);
 248         return clnt;
 249 }
 250
 251 /*
 252  * Force a portmap lookup of the remote lockd port
 253  */
 254 void
 255 nlm_rebind_host(struct nlm_host *host)
 256 {
 257         dprintk("lockd: rebind host %s\n", host->h_name);
 258         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 259                 rpc_force_rebind(host->h_rpcclnt);
 260                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 261         }
 262 }
 263
 264 /*
 265  * Increment NLM host count
 266  */
 267 struct nlm_host * nlm_get_host(struct nlm_host *host)
 268 {
 269         if (host) {
 270                 dprintk("lockd: get host %s\n", host->h_name);
 271                 atomic_inc(&host->h_count);
 272                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 273         }
 274         return host;
 275 }
 276
 277 /*
 278  * Release NLM host after use
 279  */
 280 void nlm_release_host(struct nlm_host *host)
 281 {
 282         if (host != NULL) {
 283                 dprintk("lockd: release host %s\n", host->h_name);
 284                 BUG_ON(atomic_read(&host->h_count) < 0);
 285                 if (atomic_dec_and_test(&host->h_count)) {
 286                         BUG_ON(!list_empty(&host->h_lockowners));
 287                         BUG_ON(!list_empty(&host->h_granted));
 288                         BUG_ON(!list_empty(&host->h_reclaim));
 289                 }
 290         }
 291 }
 292
 293 /*
 294  * We were notified that the host indicated by address &sin
 295  * has rebooted.
 296  * Release all resources held by that peer.
 297  */
 298 void nlm_host_rebooted(const struct sockaddr_in *sin,
 299                                 const char *hostname, int hostname_len,
 300                                 u32 new_state)
 301 {
 302         struct hlist_head *chain;
 303         struct hlist_node *pos;
 304         struct nsm_handle *nsm;
 305         struct nlm_host *host;
 306
 307         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 308                         hostname, NIPQUAD(sin->sin_addr));
 309
 310         /* Find the NSM handle for this peer */
 311         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 312                 return;
 313
 314         /* When reclaiming locks on this peer, make sure that
 315          * we set up a new notification */
 316         nsm->sm_monitored = 0;
 317
 318         /* Mark all hosts tied to this NSM state as having rebooted.
 319          * We run the loop repeatedly, because we drop the host table
 320          * lock for this.
 321          * To avoid processing a host several times, we match the nsmstate.
 322          */
 323 again:  mutex_lock(&nlm_host_mutex);
 324         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 325                 hlist_for_each_entry(host, pos, chain, h_hash) {
 326                         if (host->h_nsmhandle == nsm
 327                          && host->h_nsmstate != new_state) {
 328                                 host->h_nsmstate = new_state;
 329                                 host->h_state++;
 330
 331                                 nlm_get_host(host);
 332                                 mutex_unlock(&nlm_host_mutex);
 333
 334                                 if (host->h_server) {
 335                                         /* We're server for this guy, just ditch
 336                                          * all the locks he held. */
 337                                         nlmsvc_free_host_resources(host);
 338                                 } else {
 339                                         /* He's the server, initiate lock recovery. */
 340                                         nlmclnt_recovery(host);
 341                                 }
 342
 343                                 nlm_release_host(host);
 344                                 goto again;
 345                         }
 346                 }
 347         }
 348
 349         mutex_unlock(&nlm_host_mutex);
 350 }
 351
 352 /*
 353  * Shut down the hosts module.
 354  * Note that this routine is called only at server shutdown time.
 355  */
 356 void
 357 nlm_shutdown_hosts(void)
 358 {
 359         struct hlist_head *chain;
 360         struct hlist_node *pos;
 361         struct nlm_host *host;
 362
 363         dprintk("lockd: shutting down host module\n");
 364         mutex_lock(&nlm_host_mutex);
 365
 366         /* First, make all hosts eligible for gc */
 367         dprintk("lockd: nuking all hosts...\n");
 368         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 369                 hlist_for_each_entry(host, pos, chain, h_hash)
 370                         host->h_expires = jiffies - 1;
 371         }
 372
 373         /* Then, perform a garbage collection pass */
 374         nlm_gc_hosts();
 375         mutex_unlock(&nlm_host_mutex);
 376
 377         /* complain if any hosts are left */
 378         if (nrhosts) {
 379                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 380                 dprintk("lockd: %d hosts left:\n", nrhosts);
 381                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 382                         hlist_for_each_entry(host, pos, chain, h_hash) {
 383                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 384                                         host->h_name, atomic_read(&host->h_count),
 385                                         host->h_inuse, host->h_expires);
 386                         }
 387                 }
 388         }
 389 }
 390
 391 /*
 392  * Garbage collect any unused NLM hosts.
 393  * This GC combines reference counting for async operations with
 394  * mark & sweep for resources held by remote clients.
 395  */
 396 static void
 397 nlm_gc_hosts(void)
 398 {
 399         struct hlist_head *chain;
 400         struct hlist_node *pos, *next;
 401         struct nlm_host *host;
 402
 403         dprintk("lockd: host garbage collection\n");
 404         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 405                 hlist_for_each_entry(host, pos, chain, h_hash)
 406                         host->h_inuse = 0;
 407         }
 408
 409         /* Mark all hosts that hold locks, blocks or shares */
 410         nlmsvc_mark_resources();
 411
 412         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 413                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 414                         if (atomic_read(&host->h_count) || host->h_inuse
 415                          || time_before(jiffies, host->h_expires)) {
 416                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 417                                         host->h_name, atomic_read(&host->h_count),
 418                                         host->h_inuse, host->h_expires);
 419                                 continue;
 420                         }
 421                         dprintk("lockd: delete host %s\n", host->h_name);
 422                         hlist_del_init(&host->h_hash);
 423
 424                         nlm_destroy_host(host);
 425                         nrhosts--;
 426                 }
 427         }
 428
 429         next_gc = jiffies + NLM_HOST_COLLECT;
 430 }
 431
 432
 433 /*
 434  * Manage NSM handles
 435  */
 436 static LIST_HEAD(nsm_handles);
 437 static DEFINE_MUTEX(nsm_mutex);
 438
 439 static struct nsm_handle *
 440 __nsm_find(const struct sockaddr_in *sin,
 441                 const char *hostname, int hostname_len,
 442                 int create)
 443 {
 444         struct nsm_handle *nsm = NULL;
 445         struct list_head *pos;
 446
 447         if (!sin)
 448                 return NULL;
 449
 450         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 451                 if (printk_ratelimit()) {
 452                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 453                                             "in NFS lock request\n",
 454                                 hostname_len, hostname);
 455                 }
 456                 return NULL;
 457         }
 458
 459         mutex_lock(&nsm_mutex);
 460         list_for_each(pos, &nsm_handles) {
 461                 nsm = list_entry(pos, struct nsm_handle, sm_link);
 462
 463                 if (hostname && nsm_use_hostnames) {
 464                         if (strlen(nsm->sm_name) != hostname_len
 465                          || memcmp(nsm->sm_name, hostname, hostname_len))
 466                                 continue;
 467                 } else if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 468                         continue;
 469                 atomic_inc(&nsm->sm_count);
 470                 goto out;
 471         }
 472
 473         if (!create) {
 474                 nsm = NULL;
 475                 goto out;
 476         }
 477
 478         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 479         if (nsm != NULL) {
 480                 nsm->sm_addr = *sin;
 481                 nsm->sm_name = (char *) (nsm + 1);
 482                 memcpy(nsm->sm_name, hostname, hostname_len);
 483                 nsm->sm_name[hostname_len] = '\0';
 484                 atomic_set(&nsm->sm_count, 1);
 485
 486                 list_add(&nsm->sm_link, &nsm_handles);
 487         }
 488
 489 out:
 490         mutex_unlock(&nsm_mutex);
 491         return nsm;
 492 }
 493
 494 static struct nsm_handle *
 495 nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)
 496 {
 497         return __nsm_find(sin, hostname, hostname_len, 1);
 498 }
 499
 500 /*
 501  * Release an NSM handle
 502  */
 503 void
 504 nsm_release(struct nsm_handle *nsm)
 505 {
 506         if (!nsm)
 507                 return;
 508         if (atomic_dec_and_test(&nsm->sm_count)) {
 509                 mutex_lock(&nsm_mutex);
 510                 if (atomic_read(&nsm->sm_count) == 0) {
 511                         list_del(&nsm->sm_link);
 512                         kfree(nsm);
 513                 }
 514                 mutex_unlock(&nsm_mutex);
 515         }
 516 }