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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 *, unsigned int, int);
  38 static struct nsm_handle *      nsm_find(const struct sockaddr_in *sin,
  39                                          const char *hostname,
  40                                          unsigned 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                 unsigned int hostname_len,
  49                 const struct sockaddr_in *ssin)
  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("NIPQUAD_FMT"->"NIPQUAD_FMT
  58                         ", p=%d, v=%d, my role=%s, name=%.*s)\n",
  59                         NIPQUAD(ssin->sin_addr.s_addr),
  60                         NIPQUAD(sin->sin_addr.s_addr), proto, version,
  61                         server? "server" : "client",
  62                         hostname_len,
  63                         hostname? hostname : "<none>");
  64
  65
  66         hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
  67
  68         /* Lock hash table */
  69         mutex_lock(&nlm_host_mutex);
  70
  71         if (time_after_eq(jiffies, next_gc))
  72                 nlm_gc_hosts();
  73
  74         /* We may keep several nlm_host objects for a peer, because each
  75          * nlm_host is identified by
  76          * (address, protocol, version, server/client)
  77          * We could probably simplify this a little by putting all those
  78          * different NLM rpc_clients into one single nlm_host object.
  79          * This would allow us to have one nlm_host per address.
  80          */
  81         chain = &nlm_hosts[hash];
  82         hlist_for_each_entry(host, pos, chain, h_hash) {
  83                 if (!nlm_cmp_addr(&host->h_addr, sin))
  84                         continue;
  85
  86                 /* See if we have an NSM handle for this client */
  87                 if (!nsm)
  88                         nsm = host->h_nsmhandle;
  89
  90                 if (host->h_proto != proto)
  91                         continue;
  92                 if (host->h_version != version)
  93                         continue;
  94                 if (host->h_server != server)
  95                         continue;
  96                 if (!nlm_cmp_addr(&host->h_saddr, ssin))
  97                         continue;
  98
  99                 /* Move to head of hash chain. */
 100                 hlist_del(&host->h_hash);
 101                 hlist_add_head(&host->h_hash, chain);
 102
 103                 nlm_get_host(host);
 104                 goto out;
 105         }
 106         if (nsm)
 107                 atomic_inc(&nsm->sm_count);
 108
 109         host = NULL;
 110
 111         /* Sadly, the host isn't in our hash table yet. See if
 112          * we have an NSM handle for it. If not, create one.
 113          */
 114         if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
 115                 goto out;
 116
 117         host = kzalloc(sizeof(*host), GFP_KERNEL);
 118         if (!host) {
 119                 nsm_release(nsm);
 120                 goto out;
 121         }
 122         host->h_name       = nsm->sm_name;
 123         host->h_addr       = *sin;
 124         host->h_addr.sin_port = 0;      /* ouch! */
 125         host->h_saddr      = *ssin;
 126         host->h_version    = version;
 127         host->h_proto      = proto;
 128         host->h_rpcclnt    = NULL;
 129         mutex_init(&host->h_mutex);
 130         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 131         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 132         atomic_set(&host->h_count, 1);
 133         init_waitqueue_head(&host->h_gracewait);
 134         init_rwsem(&host->h_rwsem);
 135         host->h_state      = 0;                 /* pseudo NSM state */
 136         host->h_nsmstate   = 0;                 /* real NSM state */
 137         host->h_nsmhandle  = nsm;
 138         host->h_server     = server;
 139         hlist_add_head(&host->h_hash, chain);
 140         INIT_LIST_HEAD(&host->h_lockowners);
 141         spin_lock_init(&host->h_lock);
 142         INIT_LIST_HEAD(&host->h_granted);
 143         INIT_LIST_HEAD(&host->h_reclaim);
 144
 145         if (++nrhosts > NLM_HOST_MAX)
 146                 next_gc = 0;
 147
 148 out:
 149         mutex_unlock(&nlm_host_mutex);
 150         return host;
 151 }
 152
 153 /*
 154  * Destroy a host
 155  */
 156 static void
 157 nlm_destroy_host(struct nlm_host *host)
 158 {
 159         struct rpc_clnt *clnt;
 160
 161         BUG_ON(!list_empty(&host->h_lockowners));
 162         BUG_ON(atomic_read(&host->h_count));
 163
 164         /*
 165          * Release NSM handle and unmonitor host.
 166          */
 167         nsm_unmonitor(host);
 168
 169         clnt = host->h_rpcclnt;
 170         if (clnt != NULL)
 171                 rpc_shutdown_client(clnt);
 172         kfree(host);
 173 }
 174
 175 /*
 176  * Find an NLM server handle in the cache. If there is none, create it.
 177  */
 178 struct nlm_host *
 179 nlmclnt_lookup_host(const struct sockaddr_in *sin, int proto, int version,
 180                         const char *hostname, unsigned int hostname_len)
 181 {
 182         struct sockaddr_in ssin = {0};
 183
 184         return nlm_lookup_host(0, sin, proto, version,
 185                                hostname, hostname_len, &ssin);
 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, unsigned int hostname_len)
 194 {
 195         struct sockaddr_in ssin = {0};
 196
 197         ssin.sin_addr = rqstp->rq_daddr.addr;
 198         return nlm_lookup_host(1, svc_addr_in(rqstp),
 199                                rqstp->rq_prot, rqstp->rq_vers,
 200                                hostname, hostname_len, &ssin);
 201 }
 202
 203 /*
 204  * Create the NLM RPC client for an NLM peer
 205  */
 206 struct rpc_clnt *
 207 nlm_bind_host(struct nlm_host *host)
 208 {
 209         struct rpc_clnt *clnt;
 210
 211         dprintk("lockd: nlm_bind_host("NIPQUAD_FMT"->"NIPQUAD_FMT")\n",
 212                         NIPQUAD(host->h_saddr.sin_addr),
 213                         NIPQUAD(host->h_addr.sin_addr));
 214
 215         /* Lock host handle */
 216         mutex_lock(&host->h_mutex);
 217
 218         /* If we've already created an RPC client, check whether
 219          * RPC rebind is required
 220          */
 221         if ((clnt = host->h_rpcclnt) != NULL) {
 222                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 223                         rpc_force_rebind(clnt);
 224                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 225                         dprintk("lockd: next rebind in %ld jiffies\n",
 226                                         host->h_nextrebind - jiffies);
 227                 }
 228         } else {
 229                 unsigned long increment = nlmsvc_timeout;
 230                 struct rpc_timeout timeparms = {
 231                         .to_initval     = increment,
 232                         .to_increment   = increment,
 233                         .to_maxval      = increment * 6UL,
 234                         .to_retries     = 5U,
 235                 };
 236                 struct rpc_create_args args = {
 237                         .protocol       = host->h_proto,
 238                         .address        = (struct sockaddr *)&host->h_addr,
 239                         .addrsize       = sizeof(host->h_addr),
 240                         .saddress       = (struct sockaddr *)&host->h_saddr,
 241                         .timeout        = &timeparms,
 242                         .servername     = host->h_name,
 243                         .program        = &nlm_program,
 244                         .version        = host->h_version,
 245                         .authflavor     = RPC_AUTH_UNIX,
 246                         .flags          = (RPC_CLNT_CREATE_HARDRTRY |
 247                                            RPC_CLNT_CREATE_NOPING |
 248                                            RPC_CLNT_CREATE_AUTOBIND),
 249                 };
 250
 251                 clnt = rpc_create(&args);
 252                 if (!IS_ERR(clnt))
 253                         host->h_rpcclnt = clnt;
 254                 else {
 255                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 256                         clnt = NULL;
 257                 }
 258         }
 259
 260         mutex_unlock(&host->h_mutex);
 261         return clnt;
 262 }
 263
 264 /*
 265  * Force a portmap lookup of the remote lockd port
 266  */
 267 void
 268 nlm_rebind_host(struct nlm_host *host)
 269 {
 270         dprintk("lockd: rebind host %s\n", host->h_name);
 271         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 272                 rpc_force_rebind(host->h_rpcclnt);
 273                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 274         }
 275 }
 276
 277 /*
 278  * Increment NLM host count
 279  */
 280 struct nlm_host * nlm_get_host(struct nlm_host *host)
 281 {
 282         if (host) {
 283                 dprintk("lockd: get host %s\n", host->h_name);
 284                 atomic_inc(&host->h_count);
 285                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 286         }
 287         return host;
 288 }
 289
 290 /*
 291  * Release NLM host after use
 292  */
 293 void nlm_release_host(struct nlm_host *host)
 294 {
 295         if (host != NULL) {
 296                 dprintk("lockd: release host %s\n", host->h_name);
 297                 BUG_ON(atomic_read(&host->h_count) < 0);
 298                 if (atomic_dec_and_test(&host->h_count)) {
 299                         BUG_ON(!list_empty(&host->h_lockowners));
 300                         BUG_ON(!list_empty(&host->h_granted));
 301                         BUG_ON(!list_empty(&host->h_reclaim));
 302                 }
 303         }
 304 }
 305
 306 /*
 307  * We were notified that the host indicated by address &sin
 308  * has rebooted.
 309  * Release all resources held by that peer.
 310  */
 311 void nlm_host_rebooted(const struct sockaddr_in *sin,
 312                                 const char *hostname,
 313                                 unsigned int hostname_len,
 314                                 u32 new_state)
 315 {
 316         struct hlist_head *chain;
 317         struct hlist_node *pos;
 318         struct nsm_handle *nsm;
 319         struct nlm_host *host;
 320
 321         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 322                         hostname, NIPQUAD(sin->sin_addr));
 323
 324         /* Find the NSM handle for this peer */
 325         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 326                 return;
 327
 328         /* When reclaiming locks on this peer, make sure that
 329          * we set up a new notification */
 330         nsm->sm_monitored = 0;
 331
 332         /* Mark all hosts tied to this NSM state as having rebooted.
 333          * We run the loop repeatedly, because we drop the host table
 334          * lock for this.
 335          * To avoid processing a host several times, we match the nsmstate.
 336          */
 337 again:  mutex_lock(&nlm_host_mutex);
 338         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 339                 hlist_for_each_entry(host, pos, chain, h_hash) {
 340                         if (host->h_nsmhandle == nsm
 341                          && host->h_nsmstate != new_state) {
 342                                 host->h_nsmstate = new_state;
 343                                 host->h_state++;
 344
 345                                 nlm_get_host(host);
 346                                 mutex_unlock(&nlm_host_mutex);
 347
 348                                 if (host->h_server) {
 349                                         /* We're server for this guy, just ditch
 350                                          * all the locks he held. */
 351                                         nlmsvc_free_host_resources(host);
 352                                 } else {
 353                                         /* He's the server, initiate lock recovery. */
 354                                         nlmclnt_recovery(host);
 355                                 }
 356
 357                                 nlm_release_host(host);
 358                                 goto again;
 359                         }
 360                 }
 361         }
 362
 363         mutex_unlock(&nlm_host_mutex);
 364 }
 365
 366 /*
 367  * Shut down the hosts module.
 368  * Note that this routine is called only at server shutdown time.
 369  */
 370 void
 371 nlm_shutdown_hosts(void)
 372 {
 373         struct hlist_head *chain;
 374         struct hlist_node *pos;
 375         struct nlm_host *host;
 376
 377         dprintk("lockd: shutting down host module\n");
 378         mutex_lock(&nlm_host_mutex);
 379
 380         /* First, make all hosts eligible for gc */
 381         dprintk("lockd: nuking all hosts...\n");
 382         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 383                 hlist_for_each_entry(host, pos, chain, h_hash) {
 384                         host->h_expires = jiffies - 1;
 385                         if (host->h_rpcclnt) {
 386                                 rpc_shutdown_client(host->h_rpcclnt);
 387                                 host->h_rpcclnt = NULL;
 388                         }
 389                 }
 390         }
 391
 392         /* Then, perform a garbage collection pass */
 393         nlm_gc_hosts();
 394         mutex_unlock(&nlm_host_mutex);
 395
 396         /* complain if any hosts are left */
 397         if (nrhosts) {
 398                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 399                 dprintk("lockd: %d hosts left:\n", nrhosts);
 400                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 401                         hlist_for_each_entry(host, pos, chain, h_hash) {
 402                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 403                                         host->h_name, atomic_read(&host->h_count),
 404                                         host->h_inuse, host->h_expires);
 405                         }
 406                 }
 407         }
 408 }
 409
 410 /*
 411  * Garbage collect any unused NLM hosts.
 412  * This GC combines reference counting for async operations with
 413  * mark & sweep for resources held by remote clients.
 414  */
 415 static void
 416 nlm_gc_hosts(void)
 417 {
 418         struct hlist_head *chain;
 419         struct hlist_node *pos, *next;
 420         struct nlm_host *host;
 421
 422         dprintk("lockd: host garbage collection\n");
 423         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 424                 hlist_for_each_entry(host, pos, chain, h_hash)
 425                         host->h_inuse = 0;
 426         }
 427
 428         /* Mark all hosts that hold locks, blocks or shares */
 429         nlmsvc_mark_resources();
 430
 431         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
 432                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
 433                         if (atomic_read(&host->h_count) || host->h_inuse
 434                          || time_before(jiffies, host->h_expires)) {
 435                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 436                                         host->h_name, atomic_read(&host->h_count),
 437                                         host->h_inuse, host->h_expires);
 438                                 continue;
 439                         }
 440                         dprintk("lockd: delete host %s\n", host->h_name);
 441                         hlist_del_init(&host->h_hash);
 442
 443                         nlm_destroy_host(host);
 444                         nrhosts--;
 445                 }
 446         }
 447
 448         next_gc = jiffies + NLM_HOST_COLLECT;
 449 }
 450
 451
 452 /*
 453  * Manage NSM handles
 454  */
 455 static LIST_HEAD(nsm_handles);
 456 static DEFINE_MUTEX(nsm_mutex);
 457
 458 static struct nsm_handle *
 459 __nsm_find(const struct sockaddr_in *sin,
 460                 const char *hostname, unsigned int hostname_len,
 461                 int create)
 462 {
 463         struct nsm_handle *nsm = NULL;
 464         struct list_head *pos;
 465
 466         if (!sin)
 467                 return NULL;
 468
 469         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 470                 if (printk_ratelimit()) {
 471                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 472                                             "in NFS lock request\n",
 473                                 hostname_len, hostname);
 474                 }
 475                 return NULL;
 476         }
 477
 478         mutex_lock(&nsm_mutex);
 479         list_for_each(pos, &nsm_handles) {
 480                 nsm = list_entry(pos, struct nsm_handle, sm_link);
 481
 482                 if (hostname && nsm_use_hostnames) {
 483                         if (strlen(nsm->sm_name) != hostname_len
 484                          || memcmp(nsm->sm_name, hostname, hostname_len))
 485                                 continue;
 486                 } else if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 487                         continue;
 488                 atomic_inc(&nsm->sm_count);
 489                 goto out;
 490         }
 491
 492         if (!create) {
 493                 nsm = NULL;
 494                 goto out;
 495         }
 496
 497         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 498         if (nsm != NULL) {
 499                 nsm->sm_addr = *sin;
 500                 nsm->sm_name = (char *) (nsm + 1);
 501                 memcpy(nsm->sm_name, hostname, hostname_len);
 502                 nsm->sm_name[hostname_len] = '\0';
 503                 atomic_set(&nsm->sm_count, 1);
 504
 505                 list_add(&nsm->sm_link, &nsm_handles);
 506         }
 507
 508 out:
 509         mutex_unlock(&nsm_mutex);
 510         return nsm;
 511 }
 512
 513 static struct nsm_handle *
 514 nsm_find(const struct sockaddr_in *sin, const char *hostname,
 515          unsigned int hostname_len)
 516 {
 517         return __nsm_find(sin, hostname, hostname_len, 1);
 518 }
 519
 520 /*
 521  * Release an NSM handle
 522  */
 523 void
 524 nsm_release(struct nsm_handle *nsm)
 525 {
 526         if (!nsm)
 527                 return;
 528         if (atomic_dec_and_test(&nsm->sm_count)) {
 529                 mutex_lock(&nsm_mutex);
 530                 if (atomic_read(&nsm->sm_count) == 0) {
 531                         list_del(&nsm->sm_link);
 532                         kfree(nsm);
 533                 }
 534                 mutex_unlock(&nsm_mutex);
 535         }
 536 }