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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 static struct nsm_handle *      nsm_find(const struct sockaddr_in *sin,
  40                                          const char *hostname,
  41                                          int hostname_len);
  42
  43 /*
  44  * Common host lookup routine for server & client
  45  */
  46 static struct nlm_host *
  47 nlm_lookup_host(int server, const struct sockaddr_in *sin,
  48                                         int proto, int version,
  49                                         const char *hostname,
  50                                         int hostname_len)
  51 {
  52         struct hlist_head *chain;
  53         struct hlist_node *pos;
  54         struct nlm_host *host;
  55         struct nsm_handle *nsm = NULL;
  56         int             hash;
  57
  58         dprintk("lockd: nlm_lookup_host(%u.%u.%u.%u, p=%d, v=%d, my role=%s, name=%.*s)\n",
  59                         NIPQUAD(sin->sin_addr.s_addr), proto, version,
  60                         server? "server" : "client",
  61                         hostname_len,
  62                         hostname? hostname : "<none>");
  63
  64
  65         hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
  66
  67         /* Lock hash table */
  68         mutex_lock(&nlm_host_mutex);
  69
  70         if (time_after_eq(jiffies, next_gc))
  71                 nlm_gc_hosts();
  72
  73         /* We may keep several nlm_host objects for a peer, because each
  74          * nlm_host is identified by
  75          * (address, protocol, version, server/client)
  76          * We could probably simplify this a little by putting all those
  77          * different NLM rpc_clients into one single nlm_host object.
  78          * This would allow us to have one nlm_host per address.
  79          */
  80         chain = &nlm_hosts[hash];
  81         hlist_for_each_entry(host, pos, chain, h_hash) {
  82                 if (!nlm_cmp_addr(&host->h_addr, sin))
  83                         continue;
  84
  85                 /* See if we have an NSM handle for this client */
  86                 if (!nsm)
  87                         nsm = host->h_nsmhandle;
  88
  89                 if (host->h_proto != proto)
  90                         continue;
  91                 if (host->h_version != version)
  92                         continue;
  93                 if (host->h_server != server)
  94                         continue;
  95
  96                 /* Move to head of hash chain. */
  97                 hlist_del(&host->h_hash);
  98                 hlist_add_head(&host->h_hash, chain);
  99
 100                 nlm_get_host(host);
 101                 goto out;
 102         }
 103         if (nsm)
 104                 atomic_inc(&nsm->sm_count);
 105
 106         host = NULL;
 107
 108         /* Sadly, the host isn't in our hash table yet. See if
 109          * we have an NSM handle for it. If not, create one.
 110          */
 111         if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
 112                 goto out;
 113
 114         host = kzalloc(sizeof(*host), GFP_KERNEL);
 115         if (!host) {
 116                 nsm_release(nsm);
 117                 goto out;
 118         }
 119         host->h_name       = nsm->sm_name;
 120         host->h_addr       = *sin;
 121         host->h_addr.sin_port = 0;      /* ouch! */
 122         host->h_version    = version;
 123         host->h_proto      = proto;
 124         host->h_rpcclnt    = NULL;
 125         mutex_init(&host->h_mutex);
 126         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 127         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 128         atomic_set(&host->h_count, 1);
 129         init_waitqueue_head(&host->h_gracewait);
 130         init_rwsem(&host->h_rwsem);
 131         host->h_state      = 0;                 /* pseudo NSM state */
 132         host->h_nsmstate   = 0;                 /* real NSM state */
 133         host->h_nsmhandle  = nsm;
 134         host->h_server     = server;
 135         hlist_add_head(&host->h_hash, chain);
 136         INIT_LIST_HEAD(&host->h_lockowners);
 137         spin_lock_init(&host->h_lock);
 138         INIT_LIST_HEAD(&host->h_granted);
 139         INIT_LIST_HEAD(&host->h_reclaim);
 140
 141         if (++nrhosts > NLM_HOST_MAX)
 142                 next_gc = 0;
 143
 144 out:
 145         mutex_unlock(&nlm_host_mutex);
 146         return host;
 147 }
 148
 149 /*
 150  * Destroy a host
 151  */
 152 static void
 153 nlm_destroy_host(struct nlm_host *host)
 154 {
 155         struct rpc_clnt *clnt;
 156
 157         BUG_ON(!list_empty(&host->h_lockowners));
 158         BUG_ON(atomic_read(&host->h_count));
 159
 160         /*
 161          * Release NSM handle and unmonitor host.
 162          */
 163         nsm_unmonitor(host);
 164
 165         if ((clnt = host->h_rpcclnt) != NULL) {
 166                 if (atomic_read(&clnt->cl_users)) {
 167                         printk(KERN_WARNING
 168                                 "lockd: active RPC handle\n");
 169                         clnt->cl_dead = 1;
 170                 } else {
 171                         rpc_destroy_client(host->h_rpcclnt);
 172                 }
 173         }
 174         kfree(host);
 175 }
 176
 177 /*
 178  * Find an NLM server handle in the cache. If there is none, create it.
 179  */
 180 struct nlm_host *
 181 nlmclnt_lookup_host(const struct sockaddr_in *sin, int proto, int version,
 182                         const char *hostname, int hostname_len)
 183 {
 184         return nlm_lookup_host(0, sin, proto, version,
 185                                hostname, hostname_len);
 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, int hostname_len)
 194 {
 195         return nlm_lookup_host(1, svc_addr_in(rqstp),
 196                                rqstp->rq_prot, rqstp->rq_vers,
 197                                hostname, hostname_len);
 198 }
 199
 200 /*
 201  * Create the NLM RPC client for an NLM peer
 202  */
 203 struct rpc_clnt *
 204 nlm_bind_host(struct nlm_host *host)
 205 {
 206         struct rpc_clnt *clnt;
 207
 208         dprintk("lockd: nlm_bind_host(%08x)\n",
 209                         (unsigned)ntohl(host->h_addr.sin_addr.s_addr));
 210
 211         /* Lock host handle */
 212         mutex_lock(&host->h_mutex);
 213
 214         /* If we've already created an RPC client, check whether
 215          * RPC rebind is required
 216          */
 217         if ((clnt = host->h_rpcclnt) != NULL) {
 218                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 219                         rpc_force_rebind(clnt);
 220                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 221                         dprintk("lockd: next rebind in %ld jiffies\n",
 222                                         host->h_nextrebind - jiffies);
 223                 }
 224         } else {
 225                 unsigned long increment = nlmsvc_timeout * HZ;
 226                 struct rpc_timeout timeparms = {
 227                         .to_initval     = increment,
 228                         .to_increment   = increment,
 229                         .to_maxval      = increment * 6UL,
 230                         .to_retries     = 5U,
 231                 };
 232                 struct rpc_create_args args = {
 233                         .protocol       = host->h_proto,
 234                         .address        = (struct sockaddr *)&host->h_addr,
 235                         .addrsize       = sizeof(host->h_addr),
 236                         .timeout        = &timeparms,
 237                         .servername     = host->h_name,
 238                         .program        = &nlm_program,
 239                         .version        = host->h_version,
 240                         .authflavor     = RPC_AUTH_UNIX,
 241                         .flags          = (RPC_CLNT_CREATE_HARDRTRY |
 242                                            RPC_CLNT_CREATE_AUTOBIND),
 243                 };
 244
 245                 clnt = rpc_create(&args);
 246                 if (!IS_ERR(clnt))
 247                         host->h_rpcclnt = clnt;
 248                 else {
 249                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 250                         clnt = NULL;
 251                 }
 252         }
 253
 254         mutex_unlock(&host->h_mutex);
 255         return clnt;
 256 }
 257
 258 /*
 259  * Force a portmap lookup of the remote lockd port
 260  */
 261 void
 262 nlm_rebind_host(struct nlm_host *host)
 263 {
 264         dprintk("lockd: rebind host %s\n", host->h_name);
 265         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 266                 rpc_force_rebind(host->h_rpcclnt);
 267                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 268         }
 269 }
 270
 271 /*
 272  * Increment NLM host count
 273  */
 274 struct nlm_host * nlm_get_host(struct nlm_host *host)
 275 {
 276         if (host) {
 277                 dprintk("lockd: get host %s\n", host->h_name);
 278                 atomic_inc(&host->h_count);
 279                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 280         }
 281         return host;
 282 }
 283
 284 /*
 285  * Release NLM host after use
 286  */
 287 void nlm_release_host(struct nlm_host *host)
 288 {
 289         if (host != NULL) {
 290                 dprintk("lockd: release host %s\n", host->h_name);
 291                 BUG_ON(atomic_read(&host->h_count) < 0);
 292                 if (atomic_dec_and_test(&host->h_count)) {
 293                         BUG_ON(!list_empty(&host->h_lockowners));
 294                         BUG_ON(!list_empty(&host->h_granted));
 295                         BUG_ON(!list_empty(&host->h_reclaim));
 296                 }
 297         }
 298 }
 299
 300 /*
 301  * We were notified that the host indicated by address &sin
 302  * has rebooted.
 303  * Release all resources held by that peer.
 304  */
 305 void nlm_host_rebooted(const struct sockaddr_in *sin,
 306                                 const char *hostname, int hostname_len,
 307                                 u32 new_state)
 308 {
 309         struct hlist_head *chain;
 310         struct hlist_node *pos;
 311         struct nsm_handle *nsm;
 312         struct nlm_host *host;
 313
 314         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 315                         hostname, NIPQUAD(sin->sin_addr));
 316
 317         /* Find the NSM handle for this peer */
 318         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 319                 return;
 320
 321         /* When reclaiming locks on this peer, make sure that
 322          * we set up a new notification */
 323         nsm->sm_monitored = 0;
 324
 325         /* Mark all hosts tied to this NSM state as having rebooted.
 326          * We run the loop repeatedly, because we drop the host table
 327          * lock for this.
 328          * To avoid processing a host several times, we match the nsmstate.
 329          */
 330 again:  mutex_lock(&nlm_host_mutex);
 331         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 332                 hlist_for_each_entry(host, pos, chain, h_hash) {
 333                         if (host->h_nsmhandle == nsm
 334                          && host->h_nsmstate != new_state) {
 335                                 host->h_nsmstate = new_state;
 336                                 host->h_state++;
 337
 338                                 nlm_get_host(host);
 339                                 mutex_unlock(&nlm_host_mutex);
 340
 341                                 if (host->h_server) {
 342                                         /* We're server for this guy, just ditch
 343                                          * all the locks he held. */
 344                                         nlmsvc_free_host_resources(host);
 345                                 } else {
 346                                         /* He's the server, initiate lock recovery. */
 347                                         nlmclnt_recovery(host);
 348                                 }
 349
 350                                 nlm_release_host(host);
 351                                 goto again;
 352                         }
 353                 }
 354         }
 355
 356         mutex_unlock(&nlm_host_mutex);
 357 }
 358
 359 /*
 360  * Shut down the hosts module.
 361  * Note that this routine is called only at server shutdown time.
 362  */
 363 void
 364 nlm_shutdown_hosts(void)
 365 {
 366         struct hlist_head *chain;
 367         struct hlist_node *pos;
 368         struct nlm_host *host;
 369
 370         dprintk("lockd: shutting down host module\n");
 371         mutex_lock(&nlm_host_mutex);
 372
 373         /* First, make all hosts eligible for gc */
 374         dprintk("lockd: nuking all hosts...\n");
 375         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 376                 hlist_for_each_entry(host, pos, chain, h_hash)
 377                         host->h_expires = jiffies - 1;
 378         }
 379
 380         /* Then, perform a garbage collection pass */
 381         nlm_gc_hosts();
 382         mutex_unlock(&nlm_host_mutex);
 383
 384         /* complain if any hosts are left */
 385         if (nrhosts) {
 386                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 387                 dprintk("lockd: %d hosts left:\n", nrhosts);
 388                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 389                         hlist_for_each_entry(host, pos, chain, h_hash) {
 390                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 391                                         host->h_name, atomic_read(&host->h_count),
 392                                         host->h_inuse, host->h_expires);
 393                         }
 394                 }
 395         }
 396 }
 397
 398 /*
 399  * Garbage collect any unused NLM hosts.
 400  * This GC combines reference counting for async operations with
 401  * mark & sweep for resources held by remote clients.
 402  */
 403 static void
 404 nlm_gc_hosts(void)
 405 {
 406         struct hlist_head *chain;
 407         struct hlist_node *pos, *next;
 408         struct nlm_host *host;
 409
 410         dprintk("lockd: host garbage collection\n");
 411         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 412                 hlist_for_each_entry(host, pos, chain, h_hash)
 413                         host->h_inuse = 0;
 414         }
 415
 416         /* Mark all hosts that hold locks, blocks or shares */
 417         nlmsvc_mark_resources();
 418
 419         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 420                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 421                         if (atomic_read(&host->h_count) || host->h_inuse
 422                          || time_before(jiffies, host->h_expires)) {
 423                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 424                                         host->h_name, atomic_read(&host->h_count),
 425                                         host->h_inuse, host->h_expires);
 426                                 continue;
 427                         }
 428                         dprintk("lockd: delete host %s\n", host->h_name);
 429                         hlist_del_init(&host->h_hash);
 430
 431                         nlm_destroy_host(host);
 432                         nrhosts--;
 433                 }
 434         }
 435
 436         next_gc = jiffies + NLM_HOST_COLLECT;
 437 }
 438
 439
 440 /*
 441  * Manage NSM handles
 442  */
 443 static LIST_HEAD(nsm_handles);
 444 static DEFINE_MUTEX(nsm_mutex);
 445
 446 static struct nsm_handle *
 447 __nsm_find(const struct sockaddr_in *sin,
 448                 const char *hostname, int hostname_len,
 449                 int create)
 450 {
 451         struct nsm_handle *nsm = NULL;
 452         struct list_head *pos;
 453
 454         if (!sin)
 455                 return NULL;
 456
 457         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 458                 if (printk_ratelimit()) {
 459                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 460                                             "in NFS lock request\n",
 461                                 hostname_len, hostname);
 462                 }
 463                 return NULL;
 464         }
 465
 466         mutex_lock(&nsm_mutex);
 467         list_for_each(pos, &nsm_handles) {
 468                 nsm = list_entry(pos, struct nsm_handle, sm_link);
 469
 470                 if (hostname && nsm_use_hostnames) {
 471                         if (strlen(nsm->sm_name) != hostname_len
 472                          || memcmp(nsm->sm_name, hostname, hostname_len))
 473                                 continue;
 474                 } else if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 475                         continue;
 476                 atomic_inc(&nsm->sm_count);
 477                 goto out;
 478         }
 479
 480         if (!create) {
 481                 nsm = NULL;
 482                 goto out;
 483         }
 484
 485         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 486         if (nsm != NULL) {
 487                 nsm->sm_addr = *sin;
 488                 nsm->sm_name = (char *) (nsm + 1);
 489                 memcpy(nsm->sm_name, hostname, hostname_len);
 490                 nsm->sm_name[hostname_len] = '\0';
 491                 atomic_set(&nsm->sm_count, 1);
 492
 493                 list_add(&nsm->sm_link, &nsm_handles);
 494         }
 495
 496 out:
 497         mutex_unlock(&nsm_mutex);
 498         return nsm;
 499 }
 500
 501 static struct nsm_handle *
 502 nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)
 503 {
 504         return __nsm_find(sin, hostname, hostname_len, 1);
 505 }
 506
 507 /*
 508  * Release an NSM handle
 509  */
 510 void
 511 nsm_release(struct nsm_handle *nsm)
 512 {
 513         if (!nsm)
 514                 return;
 515         if (atomic_dec_and_test(&nsm->sm_count)) {
 516                 mutex_lock(&nsm_mutex);
 517                 if (atomic_read(&nsm->sm_count) == 0) {
 518                         list_del(&nsm->sm_link);
 519                         kfree(nsm);
 520                 }
 521                 mutex_unlock(&nsm_mutex);
 522         }
 523 }