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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, const char *hostname,
  48                 int hostname_len, const struct sockaddr_in *ssin)
  49 {
  50         struct hlist_head *chain;
  51         struct hlist_node *pos;
  52         struct nlm_host *host;
  53         struct nsm_handle *nsm = NULL;
  54         int             hash;
  55
  56         dprintk("lockd: nlm_lookup_host("NIPQUAD_FMT"->"NIPQUAD_FMT
  57                         ", p=%d, v=%d, my role=%s, name=%.*s)\n",
  58                         NIPQUAD(ssin->sin_addr.s_addr),
  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                 if (!nlm_cmp_addr(&host->h_saddr, ssin))
  96                         continue;
  97
  98                 /* Move to head of hash chain. */
  99                 hlist_del(&host->h_hash);
 100                 hlist_add_head(&host->h_hash, chain);
 101
 102                 nlm_get_host(host);
 103                 goto out;
 104         }
 105         if (nsm)
 106                 atomic_inc(&nsm->sm_count);
 107
 108         host = NULL;
 109
 110         /* Sadly, the host isn't in our hash table yet. See if
 111          * we have an NSM handle for it. If not, create one.
 112          */
 113         if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
 114                 goto out;
 115
 116         host = kzalloc(sizeof(*host), GFP_KERNEL);
 117         if (!host) {
 118                 nsm_release(nsm);
 119                 goto out;
 120         }
 121         host->h_name       = nsm->sm_name;
 122         host->h_addr       = *sin;
 123         host->h_addr.sin_port = 0;      /* ouch! */
 124         host->h_saddr      = *ssin;
 125         host->h_version    = version;
 126         host->h_proto      = proto;
 127         host->h_rpcclnt    = NULL;
 128         mutex_init(&host->h_mutex);
 129         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 130         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 131         atomic_set(&host->h_count, 1);
 132         init_waitqueue_head(&host->h_gracewait);
 133         init_rwsem(&host->h_rwsem);
 134         host->h_state      = 0;                 /* pseudo NSM state */
 135         host->h_nsmstate   = 0;                 /* real NSM state */
 136         host->h_nsmhandle  = nsm;
 137         host->h_server     = server;
 138         hlist_add_head(&host->h_hash, chain);
 139         INIT_LIST_HEAD(&host->h_lockowners);
 140         spin_lock_init(&host->h_lock);
 141         INIT_LIST_HEAD(&host->h_granted);
 142         INIT_LIST_HEAD(&host->h_reclaim);
 143
 144         if (++nrhosts > NLM_HOST_MAX)
 145                 next_gc = 0;
 146
 147 out:
 148         mutex_unlock(&nlm_host_mutex);
 149         return host;
 150 }
 151
 152 /*
 153  * Destroy a host
 154  */
 155 static void
 156 nlm_destroy_host(struct nlm_host *host)
 157 {
 158         struct rpc_clnt *clnt;
 159
 160         BUG_ON(!list_empty(&host->h_lockowners));
 161         BUG_ON(atomic_read(&host->h_count));
 162
 163         /*
 164          * Release NSM handle and unmonitor host.
 165          */
 166         nsm_unmonitor(host);
 167
 168         clnt = host->h_rpcclnt;
 169         if (clnt != NULL)
 170                 rpc_shutdown_client(clnt);
 171         kfree(host);
 172 }
 173
 174 /*
 175  * Find an NLM server handle in the cache. If there is none, create it.
 176  */
 177 struct nlm_host *
 178 nlmclnt_lookup_host(const struct sockaddr_in *sin, int proto, int version,
 179                         const char *hostname, int hostname_len)
 180 {
 181         struct sockaddr_in ssin = {0};
 182
 183         return nlm_lookup_host(0, sin, proto, version,
 184                                hostname, hostname_len, &ssin);
 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         struct sockaddr_in ssin = {0};
 195
 196         ssin.sin_addr = rqstp->rq_daddr.addr;
 197         return nlm_lookup_host(1, svc_addr_in(rqstp),
 198                                rqstp->rq_prot, rqstp->rq_vers,
 199                                hostname, hostname_len, &ssin);
 200 }
 201
 202 /*
 203  * Create the NLM RPC client for an NLM peer
 204  */
 205 struct rpc_clnt *
 206 nlm_bind_host(struct nlm_host *host)
 207 {
 208         struct rpc_clnt *clnt;
 209
 210         dprintk("lockd: nlm_bind_host("NIPQUAD_FMT"->"NIPQUAD_FMT")\n",
 211                         NIPQUAD(host->h_saddr.sin_addr),
 212                         NIPQUAD(host->h_addr.sin_addr));
 213
 214         /* Lock host handle */
 215         mutex_lock(&host->h_mutex);
 216
 217         /* If we've already created an RPC client, check whether
 218          * RPC rebind is required
 219          */
 220         if ((clnt = host->h_rpcclnt) != NULL) {
 221                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 222                         rpc_force_rebind(clnt);
 223                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 224                         dprintk("lockd: next rebind in %ld jiffies\n",
 225                                         host->h_nextrebind - jiffies);
 226                 }
 227         } else {
 228                 unsigned long increment = nlmsvc_timeout;
 229                 struct rpc_timeout timeparms = {
 230                         .to_initval     = increment,
 231                         .to_increment   = increment,
 232                         .to_maxval      = increment * 6UL,
 233                         .to_retries     = 5U,
 234                 };
 235                 struct rpc_create_args args = {
 236                         .protocol       = host->h_proto,
 237                         .address        = (struct sockaddr *)&host->h_addr,
 238                         .addrsize       = sizeof(host->h_addr),
 239                         .saddress       = (struct sockaddr *)&host->h_saddr,
 240                         .timeout        = &timeparms,
 241                         .servername     = host->h_name,
 242                         .program        = &nlm_program,
 243                         .version        = host->h_version,
 244                         .authflavor     = RPC_AUTH_UNIX,
 245                         .flags          = (RPC_CLNT_CREATE_HARDRTRY |
 246                                            RPC_CLNT_CREATE_AUTOBIND),
 247                 };
 248
 249                 clnt = rpc_create(&args);
 250                 if (!IS_ERR(clnt))
 251                         host->h_rpcclnt = clnt;
 252                 else {
 253                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 254                         clnt = NULL;
 255                 }
 256         }
 257
 258         mutex_unlock(&host->h_mutex);
 259         return clnt;
 260 }
 261
 262 /*
 263  * Force a portmap lookup of the remote lockd port
 264  */
 265 void
 266 nlm_rebind_host(struct nlm_host *host)
 267 {
 268         dprintk("lockd: rebind host %s\n", host->h_name);
 269         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 270                 rpc_force_rebind(host->h_rpcclnt);
 271                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 272         }
 273 }
 274
 275 /*
 276  * Increment NLM host count
 277  */
 278 struct nlm_host * nlm_get_host(struct nlm_host *host)
 279 {
 280         if (host) {
 281                 dprintk("lockd: get host %s\n", host->h_name);
 282                 atomic_inc(&host->h_count);
 283                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 284         }
 285         return host;
 286 }
 287
 288 /*
 289  * Release NLM host after use
 290  */
 291 void nlm_release_host(struct nlm_host *host)
 292 {
 293         if (host != NULL) {
 294                 dprintk("lockd: release host %s\n", host->h_name);
 295                 BUG_ON(atomic_read(&host->h_count) < 0);
 296                 if (atomic_dec_and_test(&host->h_count)) {
 297                         BUG_ON(!list_empty(&host->h_lockowners));
 298                         BUG_ON(!list_empty(&host->h_granted));
 299                         BUG_ON(!list_empty(&host->h_reclaim));
 300                 }
 301         }
 302 }
 303
 304 /*
 305  * We were notified that the host indicated by address &sin
 306  * has rebooted.
 307  * Release all resources held by that peer.
 308  */
 309 void nlm_host_rebooted(const struct sockaddr_in *sin,
 310                                 const char *hostname, int hostname_len,
 311                                 u32 new_state)
 312 {
 313         struct hlist_head *chain;
 314         struct hlist_node *pos;
 315         struct nsm_handle *nsm;
 316         struct nlm_host *host;
 317
 318         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 319                         hostname, NIPQUAD(sin->sin_addr));
 320
 321         /* Find the NSM handle for this peer */
 322         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 323                 return;
 324
 325         /* When reclaiming locks on this peer, make sure that
 326          * we set up a new notification */
 327         nsm->sm_monitored = 0;
 328
 329         /* Mark all hosts tied to this NSM state as having rebooted.
 330          * We run the loop repeatedly, because we drop the host table
 331          * lock for this.
 332          * To avoid processing a host several times, we match the nsmstate.
 333          */
 334 again:  mutex_lock(&nlm_host_mutex);
 335         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 336                 hlist_for_each_entry(host, pos, chain, h_hash) {
 337                         if (host->h_nsmhandle == nsm
 338                          && host->h_nsmstate != new_state) {
 339                                 host->h_nsmstate = new_state;
 340                                 host->h_state++;
 341
 342                                 nlm_get_host(host);
 343                                 mutex_unlock(&nlm_host_mutex);
 344
 345                                 if (host->h_server) {
 346                                         /* We're server for this guy, just ditch
 347                                          * all the locks he held. */
 348                                         nlmsvc_free_host_resources(host);
 349                                 } else {
 350                                         /* He's the server, initiate lock recovery. */
 351                                         nlmclnt_recovery(host);
 352                                 }
 353
 354                                 nlm_release_host(host);
 355                                 goto again;
 356                         }
 357                 }
 358         }
 359
 360         mutex_unlock(&nlm_host_mutex);
 361 }
 362
 363 /*
 364  * Shut down the hosts module.
 365  * Note that this routine is called only at server shutdown time.
 366  */
 367 void
 368 nlm_shutdown_hosts(void)
 369 {
 370         struct hlist_head *chain;
 371         struct hlist_node *pos;
 372         struct nlm_host *host;
 373
 374         dprintk("lockd: shutting down host module\n");
 375         mutex_lock(&nlm_host_mutex);
 376
 377         /* First, make all hosts eligible for gc */
 378         dprintk("lockd: nuking all hosts...\n");
 379         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 380                 hlist_for_each_entry(host, pos, chain, h_hash)
 381                         host->h_expires = jiffies - 1;
 382         }
 383
 384         /* Then, perform a garbage collection pass */
 385         nlm_gc_hosts();
 386         mutex_unlock(&nlm_host_mutex);
 387
 388         /* complain if any hosts are left */
 389         if (nrhosts) {
 390                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 391                 dprintk("lockd: %d hosts left:\n", nrhosts);
 392                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 393                         hlist_for_each_entry(host, pos, chain, h_hash) {
 394                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 395                                         host->h_name, atomic_read(&host->h_count),
 396                                         host->h_inuse, host->h_expires);
 397                         }
 398                 }
 399         }
 400 }
 401
 402 /*
 403  * Garbage collect any unused NLM hosts.
 404  * This GC combines reference counting for async operations with
 405  * mark & sweep for resources held by remote clients.
 406  */
 407 static void
 408 nlm_gc_hosts(void)
 409 {
 410         struct hlist_head *chain;
 411         struct hlist_node *pos, *next;
 412         struct nlm_host *host;
 413
 414         dprintk("lockd: host garbage collection\n");
 415         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 416                 hlist_for_each_entry(host, pos, chain, h_hash)
 417                         host->h_inuse = 0;
 418         }
 419
 420         /* Mark all hosts that hold locks, blocks or shares */
 421         nlmsvc_mark_resources();
 422
 423         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 424                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 425                         if (atomic_read(&host->h_count) || host->h_inuse
 426                          || time_before(jiffies, host->h_expires)) {
 427                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 428                                         host->h_name, atomic_read(&host->h_count),
 429                                         host->h_inuse, host->h_expires);
 430                                 continue;
 431                         }
 432                         dprintk("lockd: delete host %s\n", host->h_name);
 433                         hlist_del_init(&host->h_hash);
 434
 435                         nlm_destroy_host(host);
 436                         nrhosts--;
 437                 }
 438         }
 439
 440         next_gc = jiffies + NLM_HOST_COLLECT;
 441 }
 442
 443
 444 /*
 445  * Manage NSM handles
 446  */
 447 static LIST_HEAD(nsm_handles);
 448 static DEFINE_MUTEX(nsm_mutex);
 449
 450 static struct nsm_handle *
 451 __nsm_find(const struct sockaddr_in *sin,
 452                 const char *hostname, int hostname_len,
 453                 int create)
 454 {
 455         struct nsm_handle *nsm = NULL;
 456         struct list_head *pos;
 457
 458         if (!sin)
 459                 return NULL;
 460
 461         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 462                 if (printk_ratelimit()) {
 463                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 464                                             "in NFS lock request\n",
 465                                 hostname_len, hostname);
 466                 }
 467                 return NULL;
 468         }
 469
 470         mutex_lock(&nsm_mutex);
 471         list_for_each(pos, &nsm_handles) {
 472                 nsm = list_entry(pos, struct nsm_handle, sm_link);
 473
 474                 if (hostname && nsm_use_hostnames) {
 475                         if (strlen(nsm->sm_name) != hostname_len
 476                          || memcmp(nsm->sm_name, hostname, hostname_len))
 477                                 continue;
 478                 } else if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 479                         continue;
 480                 atomic_inc(&nsm->sm_count);
 481                 goto out;
 482         }
 483
 484         if (!create) {
 485                 nsm = NULL;
 486                 goto out;
 487         }
 488
 489         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 490         if (nsm != NULL) {
 491                 nsm->sm_addr = *sin;
 492                 nsm->sm_name = (char *) (nsm + 1);
 493                 memcpy(nsm->sm_name, hostname, hostname_len);
 494                 nsm->sm_name[hostname_len] = '\0';
 495                 atomic_set(&nsm->sm_count, 1);
 496
 497                 list_add(&nsm->sm_link, &nsm_handles);
 498         }
 499
 500 out:
 501         mutex_unlock(&nsm_mutex);
 502         return nsm;
 503 }
 504
 505 static struct nsm_handle *
 506 nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)
 507 {
 508         return __nsm_find(sin, hostname, hostname_len, 1);
 509 }
 510
 511 /*
 512  * Release an NSM handle
 513  */
 514 void
 515 nsm_release(struct nsm_handle *nsm)
 516 {
 517         if (!nsm)
 518                 return;
 519         if (atomic_dec_and_test(&nsm->sm_count)) {
 520                 mutex_lock(&nsm_mutex);
 521                 if (atomic_read(&nsm->sm_count) == 0) {
 522                         list_del(&nsm->sm_link);
 523                         kfree(nsm);
 524                 }
 525                 mutex_unlock(&nsm_mutex);
 526         }
 527 }