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/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 && (nsm = host->h_nsmhandle) != 0)
 107                         atomic_inc(&nsm->sm_count);
 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
 124         host = NULL;
 125
 126         /* Sadly, the host isn't in our hash table yet. See if
 127          * we have an NSM handle for it. If not, create one.
 128          */
 129         if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
 130                 goto out;
 131
 132         host = kzalloc(sizeof(*host), GFP_KERNEL);
 133         if (!host) {
 134                 nsm_release(nsm);
 135                 goto out;
 136         }
 137         host->h_name       = nsm->sm_name;
 138         host->h_addr       = *sin;
 139         host->h_addr.sin_port = 0;      /* ouch! */
 140         host->h_version    = version;
 141         host->h_proto      = proto;
 142         host->h_rpcclnt    = NULL;
 143         mutex_init(&host->h_mutex);
 144         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 145         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 146         atomic_set(&host->h_count, 1);
 147         init_waitqueue_head(&host->h_gracewait);
 148         init_rwsem(&host->h_rwsem);
 149         host->h_state      = 0;                 /* pseudo NSM state */
 150         host->h_nsmstate   = 0;                 /* real NSM state */
 151         host->h_nsmhandle  = nsm;
 152         host->h_server     = server;
 153         hlist_add_head(&host->h_hash, chain);
 154         INIT_LIST_HEAD(&host->h_lockowners);
 155         spin_lock_init(&host->h_lock);
 156         INIT_LIST_HEAD(&host->h_granted);
 157         INIT_LIST_HEAD(&host->h_reclaim);
 158
 159         if (++nrhosts > NLM_HOST_MAX)
 160                 next_gc = 0;
 161
 162 out:
 163         mutex_unlock(&nlm_host_mutex);
 164         return host;
 165 }
 166
 167 /*
 168  * Destroy a host
 169  */
 170 static void
 171 nlm_destroy_host(struct nlm_host *host)
 172 {
 173         struct rpc_clnt *clnt;
 174
 175         BUG_ON(!list_empty(&host->h_lockowners));
 176         BUG_ON(atomic_read(&host->h_count));
 177
 178         /*
 179          * Release NSM handle and unmonitor host.
 180          */
 181         nsm_unmonitor(host);
 182
 183         if ((clnt = host->h_rpcclnt) != NULL) {
 184                 if (atomic_read(&clnt->cl_users)) {
 185                         printk(KERN_WARNING
 186                                 "lockd: active RPC handle\n");
 187                         clnt->cl_dead = 1;
 188                 } else {
 189                         rpc_destroy_client(host->h_rpcclnt);
 190                 }
 191         }
 192         kfree(host);
 193 }
 194
 195 struct nlm_host *
 196 nlm_find_client(void)
 197 {
 198         struct hlist_head *chain;
 199         struct hlist_node *pos;
 200
 201         /* find a nlm_host for a client for which h_killed == 0.
 202          * and return it
 203          */
 204         mutex_lock(&nlm_host_mutex);
 205         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 206                 struct nlm_host *host;
 207
 208                 hlist_for_each_entry(host, pos, chain, h_hash) {
 209                         if (host->h_server &&
 210                             host->h_killed == 0) {
 211                                 nlm_get_host(host);
 212                                 mutex_unlock(&nlm_host_mutex);
 213                                 return host;
 214                         }
 215                 }
 216         }
 217         mutex_unlock(&nlm_host_mutex);
 218         return NULL;
 219 }
 220
 221
 222 /*
 223  * Create the NLM RPC client for an NLM peer
 224  */
 225 struct rpc_clnt *
 226 nlm_bind_host(struct nlm_host *host)
 227 {
 228         struct rpc_clnt *clnt;
 229
 230         dprintk("lockd: nlm_bind_host(%08x)\n",
 231                         (unsigned)ntohl(host->h_addr.sin_addr.s_addr));
 232
 233         /* Lock host handle */
 234         mutex_lock(&host->h_mutex);
 235
 236         /* If we've already created an RPC client, check whether
 237          * RPC rebind is required
 238          */
 239         if ((clnt = host->h_rpcclnt) != NULL) {
 240                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 241                         rpc_force_rebind(clnt);
 242                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 243                         dprintk("lockd: next rebind in %ld jiffies\n",
 244                                         host->h_nextrebind - jiffies);
 245                 }
 246         } else {
 247                 unsigned long increment = nlmsvc_timeout * HZ;
 248                 struct rpc_timeout timeparms = {
 249                         .to_initval     = increment,
 250                         .to_increment   = increment,
 251                         .to_maxval      = increment * 6UL,
 252                         .to_retries     = 5U,
 253                 };
 254                 struct rpc_create_args args = {
 255                         .protocol       = host->h_proto,
 256                         .address        = (struct sockaddr *)&host->h_addr,
 257                         .addrsize       = sizeof(host->h_addr),
 258                         .timeout        = &timeparms,
 259                         .servername     = host->h_name,
 260                         .program        = &nlm_program,
 261                         .version        = host->h_version,
 262                         .authflavor     = RPC_AUTH_UNIX,
 263                         .flags          = (RPC_CLNT_CREATE_HARDRTRY |
 264                                            RPC_CLNT_CREATE_AUTOBIND),
 265                 };
 266
 267                 clnt = rpc_create(&args);
 268                 if (!IS_ERR(clnt))
 269                         host->h_rpcclnt = clnt;
 270                 else {
 271                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 272                         clnt = NULL;
 273                 }
 274         }
 275
 276         mutex_unlock(&host->h_mutex);
 277         return clnt;
 278 }
 279
 280 /*
 281  * Force a portmap lookup of the remote lockd port
 282  */
 283 void
 284 nlm_rebind_host(struct nlm_host *host)
 285 {
 286         dprintk("lockd: rebind host %s\n", host->h_name);
 287         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 288                 rpc_force_rebind(host->h_rpcclnt);
 289                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 290         }
 291 }
 292
 293 /*
 294  * Increment NLM host count
 295  */
 296 struct nlm_host * nlm_get_host(struct nlm_host *host)
 297 {
 298         if (host) {
 299                 dprintk("lockd: get host %s\n", host->h_name);
 300                 atomic_inc(&host->h_count);
 301                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 302         }
 303         return host;
 304 }
 305
 306 /*
 307  * Release NLM host after use
 308  */
 309 void nlm_release_host(struct nlm_host *host)
 310 {
 311         if (host != NULL) {
 312                 dprintk("lockd: release host %s\n", host->h_name);
 313                 BUG_ON(atomic_read(&host->h_count) < 0);
 314                 if (atomic_dec_and_test(&host->h_count)) {
 315                         BUG_ON(!list_empty(&host->h_lockowners));
 316                         BUG_ON(!list_empty(&host->h_granted));
 317                         BUG_ON(!list_empty(&host->h_reclaim));
 318                 }
 319         }
 320 }
 321
 322 /*
 323  * We were notified that the host indicated by address &sin
 324  * has rebooted.
 325  * Release all resources held by that peer.
 326  */
 327 void nlm_host_rebooted(const struct sockaddr_in *sin,
 328                                 const char *hostname, int hostname_len,
 329                                 u32 new_state)
 330 {
 331         struct hlist_head *chain;
 332         struct hlist_node *pos;
 333         struct nsm_handle *nsm;
 334         struct nlm_host *host;
 335
 336         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 337                         hostname, NIPQUAD(sin->sin_addr));
 338
 339         /* Find the NSM handle for this peer */
 340         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 341                 return;
 342
 343         /* When reclaiming locks on this peer, make sure that
 344          * we set up a new notification */
 345         nsm->sm_monitored = 0;
 346
 347         /* Mark all hosts tied to this NSM state as having rebooted.
 348          * We run the loop repeatedly, because we drop the host table
 349          * lock for this.
 350          * To avoid processing a host several times, we match the nsmstate.
 351          */
 352 again:  mutex_lock(&nlm_host_mutex);
 353         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 354                 hlist_for_each_entry(host, pos, chain, h_hash) {
 355                         if (host->h_nsmhandle == nsm
 356                          && host->h_nsmstate != new_state) {
 357                                 host->h_nsmstate = new_state;
 358                                 host->h_state++;
 359
 360                                 nlm_get_host(host);
 361                                 mutex_unlock(&nlm_host_mutex);
 362
 363                                 if (host->h_server) {
 364                                         /* We're server for this guy, just ditch
 365                                          * all the locks he held. */
 366                                         nlmsvc_free_host_resources(host);
 367                                 } else {
 368                                         /* He's the server, initiate lock recovery. */
 369                                         nlmclnt_recovery(host);
 370                                 }
 371
 372                                 nlm_release_host(host);
 373                                 goto again;
 374                         }
 375                 }
 376         }
 377
 378         mutex_unlock(&nlm_host_mutex);
 379 }
 380
 381 /*
 382  * Shut down the hosts module.
 383  * Note that this routine is called only at server shutdown time.
 384  */
 385 void
 386 nlm_shutdown_hosts(void)
 387 {
 388         struct hlist_head *chain;
 389         struct hlist_node *pos;
 390         struct nlm_host *host;
 391
 392         dprintk("lockd: shutting down host module\n");
 393         mutex_lock(&nlm_host_mutex);
 394
 395         /* First, make all hosts eligible for gc */
 396         dprintk("lockd: nuking all hosts...\n");
 397         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 398                 hlist_for_each_entry(host, pos, chain, h_hash)
 399                         host->h_expires = jiffies - 1;
 400         }
 401
 402         /* Then, perform a garbage collection pass */
 403         nlm_gc_hosts();
 404         mutex_unlock(&nlm_host_mutex);
 405
 406         /* complain if any hosts are left */
 407         if (nrhosts) {
 408                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 409                 dprintk("lockd: %d hosts left:\n", nrhosts);
 410                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 411                         hlist_for_each_entry(host, pos, chain, h_hash) {
 412                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 413                                         host->h_name, atomic_read(&host->h_count),
 414                                         host->h_inuse, host->h_expires);
 415                         }
 416                 }
 417         }
 418 }
 419
 420 /*
 421  * Garbage collect any unused NLM hosts.
 422  * This GC combines reference counting for async operations with
 423  * mark & sweep for resources held by remote clients.
 424  */
 425 static void
 426 nlm_gc_hosts(void)
 427 {
 428         struct hlist_head *chain;
 429         struct hlist_node *pos, *next;
 430         struct nlm_host *host;
 431
 432         dprintk("lockd: host garbage collection\n");
 433         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 434                 hlist_for_each_entry(host, pos, chain, h_hash)
 435                         host->h_inuse = 0;
 436         }
 437
 438         /* Mark all hosts that hold locks, blocks or shares */
 439         nlmsvc_mark_resources();
 440
 441         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 442                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 443                         if (atomic_read(&host->h_count) || host->h_inuse
 444                          || time_before(jiffies, host->h_expires)) {
 445                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 446                                         host->h_name, atomic_read(&host->h_count),
 447                                         host->h_inuse, host->h_expires);
 448                                 continue;
 449                         }
 450                         dprintk("lockd: delete host %s\n", host->h_name);
 451                         hlist_del_init(&host->h_hash);
 452
 453                         nlm_destroy_host(host);
 454                         nrhosts--;
 455                 }
 456         }
 457
 458         next_gc = jiffies + NLM_HOST_COLLECT;
 459 }
 460
 461
 462 /*
 463  * Manage NSM handles
 464  */
 465 static LIST_HEAD(nsm_handles);
 466 static DECLARE_MUTEX(nsm_sema);
 467
 468 static struct nsm_handle *
 469 __nsm_find(const struct sockaddr_in *sin,
 470                 const char *hostname, int hostname_len,
 471                 int create)
 472 {
 473         struct nsm_handle *nsm = NULL;
 474         struct list_head *pos;
 475
 476         if (!sin)
 477                 return NULL;
 478
 479         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 480                 if (printk_ratelimit()) {
 481                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 482                                             "in NFS lock request\n",
 483                                 hostname_len, hostname);
 484                 }
 485                 return NULL;
 486         }
 487
 488         down(&nsm_sema);
 489         list_for_each(pos, &nsm_handles) {
 490                 nsm = list_entry(pos, struct nsm_handle, sm_link);
 491
 492                 if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 493                         continue;
 494                 atomic_inc(&nsm->sm_count);
 495                 goto out;
 496         }
 497
 498         if (!create) {
 499                 nsm = NULL;
 500                 goto out;
 501         }
 502
 503         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 504         if (nsm != NULL) {
 505                 nsm->sm_addr = *sin;
 506                 nsm->sm_name = (char *) (nsm + 1);
 507                 memcpy(nsm->sm_name, hostname, hostname_len);
 508                 nsm->sm_name[hostname_len] = '\0';
 509                 atomic_set(&nsm->sm_count, 1);
 510
 511                 list_add(&nsm->sm_link, &nsm_handles);
 512         }
 513
 514 out:    up(&nsm_sema);
 515         return nsm;
 516 }
 517
 518 struct nsm_handle *
 519 nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)
 520 {
 521         return __nsm_find(sin, hostname, hostname_len, 1);
 522 }
 523
 524 /*
 525  * Release an NSM handle
 526  */
 527 void
 528 nsm_release(struct nsm_handle *nsm)
 529 {
 530         if (!nsm)
 531                 return;
 532         if (atomic_dec_and_test(&nsm->sm_count)) {
 533                 down(&nsm_sema);
 534                 if (atomic_read(&nsm->sm_count) == 0) {
 535                         list_del(&nsm->sm_link);
 536                         kfree(nsm);
 537                 }
 538                 up(&nsm_sema);
 539         }
 540 }