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