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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 nlm_host *        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 nlm_host *host, **hp;
  73         struct nsm_handle *nsm = NULL;
  74         int             hash;
  75
  76         dprintk("lockd: nlm_lookup_host(%u.%u.%u.%u, p=%d, v=%d, my role=%s, name=%.*s)\n",
  77                         NIPQUAD(sin->sin_addr.s_addr), proto, version,
  78                         server? "server" : "client",
  79                         hostname_len,
  80                         hostname? hostname : "<none>");
  81
  82
  83         hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
  84
  85         /* Lock hash table */
  86         mutex_lock(&nlm_host_mutex);
  87
  88         if (time_after_eq(jiffies, next_gc))
  89                 nlm_gc_hosts();
  90
  91         /* We may keep several nlm_host objects for a peer, because each
  92          * nlm_host is identified by
  93          * (address, protocol, version, server/client)
  94          * We could probably simplify this a little by putting all those
  95          * different NLM rpc_clients into one single nlm_host object.
  96          * This would allow us to have one nlm_host per address.
  97          */
  98         for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
  99                 if (!nlm_cmp_addr(&host->h_addr, sin))
 100                         continue;
 101
 102                 /* See if we have an NSM handle for this client */
 103                 if (!nsm && (nsm = host->h_nsmhandle) != 0)
 104                         atomic_inc(&nsm->sm_count);
 105
 106                 if (host->h_proto != proto)
 107                         continue;
 108                 if (host->h_version != version)
 109                         continue;
 110                 if (host->h_server != server)
 111                         continue;
 112
 113                 if (hp != nlm_hosts + hash) {
 114                         *hp = host->h_next;
 115                         host->h_next = nlm_hosts[hash];
 116                         nlm_hosts[hash] = host;
 117                 }
 118                 nlm_get_host(host);
 119                 goto out;
 120         }
 121
 122         /* Sadly, the host isn't in our hash table yet. See if
 123          * we have an NSM handle for it. If not, create one.
 124          */
 125         if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
 126                 goto out;
 127
 128         host = kzalloc(sizeof(*host), GFP_KERNEL);
 129         if (!host) {
 130                 nsm_release(nsm);
 131                 goto out;
 132         }
 133         host->h_name       = nsm->sm_name;
 134         host->h_addr       = *sin;
 135         host->h_addr.sin_port = 0;      /* ouch! */
 136         host->h_version    = version;
 137         host->h_proto      = proto;
 138         host->h_rpcclnt    = NULL;
 139         mutex_init(&host->h_mutex);
 140         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 141         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 142         atomic_set(&host->h_count, 1);
 143         init_waitqueue_head(&host->h_gracewait);
 144         init_rwsem(&host->h_rwsem);
 145         host->h_state      = 0;                 /* pseudo NSM state */
 146         host->h_nsmstate   = 0;                 /* real NSM state */
 147         host->h_nsmhandle  = nsm;
 148         host->h_server     = server;
 149         host->h_next       = nlm_hosts[hash];
 150         nlm_hosts[hash]    = host;
 151         INIT_LIST_HEAD(&host->h_lockowners);
 152         spin_lock_init(&host->h_lock);
 153         INIT_LIST_HEAD(&host->h_granted);
 154         INIT_LIST_HEAD(&host->h_reclaim);
 155
 156         if (++nrhosts > NLM_HOST_MAX)
 157                 next_gc = 0;
 158
 159 out:
 160         mutex_unlock(&nlm_host_mutex);
 161         return host;
 162 }
 163
 164 struct nlm_host *
 165 nlm_find_client(void)
 166 {
 167         /* find a nlm_host for a client for which h_killed == 0.
 168          * and return it
 169          */
 170         int hash;
 171         mutex_lock(&nlm_host_mutex);
 172         for (hash = 0 ; hash < NLM_HOST_NRHASH; hash++) {
 173                 struct nlm_host *host, **hp;
 174                 for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
 175                         if (host->h_server &&
 176                             host->h_killed == 0) {
 177                                 nlm_get_host(host);
 178                                 mutex_unlock(&nlm_host_mutex);
 179                                 return host;
 180                         }
 181                 }
 182         }
 183         mutex_unlock(&nlm_host_mutex);
 184         return NULL;
 185 }
 186
 187
 188 /*
 189  * Create the NLM RPC client for an NLM peer
 190  */
 191 struct rpc_clnt *
 192 nlm_bind_host(struct nlm_host *host)
 193 {
 194         struct rpc_clnt *clnt;
 195
 196         dprintk("lockd: nlm_bind_host(%08x)\n",
 197                         (unsigned)ntohl(host->h_addr.sin_addr.s_addr));
 198
 199         /* Lock host handle */
 200         mutex_lock(&host->h_mutex);
 201
 202         /* If we've already created an RPC client, check whether
 203          * RPC rebind is required
 204          */
 205         if ((clnt = host->h_rpcclnt) != NULL) {
 206                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 207                         rpc_force_rebind(clnt);
 208                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 209                         dprintk("lockd: next rebind in %ld jiffies\n",
 210                                         host->h_nextrebind - jiffies);
 211                 }
 212         } else {
 213                 unsigned long increment = nlmsvc_timeout * HZ;
 214                 struct rpc_timeout timeparms = {
 215                         .to_initval     = increment,
 216                         .to_increment   = increment,
 217                         .to_maxval      = increment * 6UL,
 218                         .to_retries     = 5U,
 219                 };
 220                 struct rpc_create_args args = {
 221                         .protocol       = host->h_proto,
 222                         .address        = (struct sockaddr *)&host->h_addr,
 223                         .addrsize       = sizeof(host->h_addr),
 224                         .timeout        = &timeparms,
 225                         .servername     = host->h_name,
 226                         .program        = &nlm_program,
 227                         .version        = host->h_version,
 228                         .authflavor     = RPC_AUTH_UNIX,
 229                         .flags          = (RPC_CLNT_CREATE_HARDRTRY |
 230                                            RPC_CLNT_CREATE_AUTOBIND),
 231                 };
 232
 233                 clnt = rpc_create(&args);
 234                 if (!IS_ERR(clnt))
 235                         host->h_rpcclnt = clnt;
 236                 else {
 237                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 238                         clnt = NULL;
 239                 }
 240         }
 241
 242         mutex_unlock(&host->h_mutex);
 243         return clnt;
 244 }
 245
 246 /*
 247  * Force a portmap lookup of the remote lockd port
 248  */
 249 void
 250 nlm_rebind_host(struct nlm_host *host)
 251 {
 252         dprintk("lockd: rebind host %s\n", host->h_name);
 253         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 254                 rpc_force_rebind(host->h_rpcclnt);
 255                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 256         }
 257 }
 258
 259 /*
 260  * Increment NLM host count
 261  */
 262 struct nlm_host * nlm_get_host(struct nlm_host *host)
 263 {
 264         if (host) {
 265                 dprintk("lockd: get host %s\n", host->h_name);
 266                 atomic_inc(&host->h_count);
 267                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 268         }
 269         return host;
 270 }
 271
 272 /*
 273  * Release NLM host after use
 274  */
 275 void nlm_release_host(struct nlm_host *host)
 276 {
 277         if (host != NULL) {
 278                 dprintk("lockd: release host %s\n", host->h_name);
 279                 BUG_ON(atomic_read(&host->h_count) < 0);
 280                 if (atomic_dec_and_test(&host->h_count)) {
 281                         BUG_ON(!list_empty(&host->h_lockowners));
 282                         BUG_ON(!list_empty(&host->h_granted));
 283                         BUG_ON(!list_empty(&host->h_reclaim));
 284                 }
 285         }
 286 }
 287
 288 /*
 289  * We were notified that the host indicated by address &sin
 290  * has rebooted.
 291  * Release all resources held by that peer.
 292  */
 293 void nlm_host_rebooted(const struct sockaddr_in *sin,
 294                                 const char *hostname, int hostname_len,
 295                                 u32 new_state)
 296 {
 297         struct nsm_handle *nsm;
 298         struct nlm_host *host, **hp;
 299         int             hash;
 300
 301         dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",
 302                         hostname, NIPQUAD(sin->sin_addr));
 303
 304         /* Find the NSM handle for this peer */
 305         if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))
 306                 return;
 307
 308         /* When reclaiming locks on this peer, make sure that
 309          * we set up a new notification */
 310         nsm->sm_monitored = 0;
 311
 312         /* Mark all hosts tied to this NSM state as having rebooted.
 313          * We run the loop repeatedly, because we drop the host table
 314          * lock for this.
 315          * To avoid processing a host several times, we match the nsmstate.
 316          */
 317 again:  mutex_lock(&nlm_host_mutex);
 318         for (hash = 0; hash < NLM_HOST_NRHASH; hash++) {
 319                 for (hp = &nlm_hosts[hash]; (host = *hp); hp = &host->h_next) {
 320                         if (host->h_nsmhandle == nsm
 321                          && host->h_nsmstate != new_state) {
 322                                 host->h_nsmstate = new_state;
 323                                 host->h_state++;
 324
 325                                 nlm_get_host(host);
 326                                 mutex_unlock(&nlm_host_mutex);
 327
 328                                 if (host->h_server) {
 329                                         /* We're server for this guy, just ditch
 330                                          * all the locks he held. */
 331                                         nlmsvc_free_host_resources(host);
 332                                 } else {
 333                                         /* He's the server, initiate lock recovery. */
 334                                         nlmclnt_recovery(host);
 335                                 }
 336
 337                                 nlm_release_host(host);
 338                                 goto again;
 339                         }
 340                 }
 341         }
 342
 343         mutex_unlock(&nlm_host_mutex);
 344 }
 345
 346 /*
 347  * Shut down the hosts module.
 348  * Note that this routine is called only at server shutdown time.
 349  */
 350 void
 351 nlm_shutdown_hosts(void)
 352 {
 353         struct nlm_host *host;
 354         int             i;
 355
 356         dprintk("lockd: shutting down host module\n");
 357         mutex_lock(&nlm_host_mutex);
 358
 359         /* First, make all hosts eligible for gc */
 360         dprintk("lockd: nuking all hosts...\n");
 361         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 362                 for (host = nlm_hosts[i]; host; host = host->h_next)
 363                         host->h_expires = jiffies - 1;
 364         }
 365
 366         /* Then, perform a garbage collection pass */
 367         nlm_gc_hosts();
 368         mutex_unlock(&nlm_host_mutex);
 369
 370         /* complain if any hosts are left */
 371         if (nrhosts) {
 372                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 373                 dprintk("lockd: %d hosts left:\n", nrhosts);
 374                 for (i = 0; i < NLM_HOST_NRHASH; i++) {
 375                         for (host = nlm_hosts[i]; host; host = host->h_next) {
 376                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 377                                         host->h_name, atomic_read(&host->h_count),
 378                                         host->h_inuse, host->h_expires);
 379                         }
 380                 }
 381         }
 382 }
 383
 384 /*
 385  * Garbage collect any unused NLM hosts.
 386  * This GC combines reference counting for async operations with
 387  * mark & sweep for resources held by remote clients.
 388  */
 389 static void
 390 nlm_gc_hosts(void)
 391 {
 392         struct nlm_host **q, *host;
 393         struct rpc_clnt *clnt;
 394         int             i;
 395
 396         dprintk("lockd: host garbage collection\n");
 397         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 398                 for (host = nlm_hosts[i]; host; host = host->h_next)
 399                         host->h_inuse = 0;
 400         }
 401
 402         /* Mark all hosts that hold locks, blocks or shares */
 403         nlmsvc_mark_resources();
 404
 405         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 406                 q = &nlm_hosts[i];
 407                 while ((host = *q) != NULL) {
 408                         if (atomic_read(&host->h_count) || host->h_inuse
 409                          || time_before(jiffies, host->h_expires)) {
 410                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 411                                         host->h_name, atomic_read(&host->h_count),
 412                                         host->h_inuse, host->h_expires);
 413                                 q = &host->h_next;
 414                                 continue;
 415                         }
 416                         dprintk("lockd: delete host %s\n", host->h_name);
 417                         *q = host->h_next;
 418
 419                         /*
 420                          * Unmonitor unless host was invalidated (i.e. lockd restarted)
 421                          */
 422                         nsm_unmonitor(host);
 423
 424                         if ((clnt = host->h_rpcclnt) != NULL) {
 425                                 if (atomic_read(&clnt->cl_users)) {
 426                                         printk(KERN_WARNING
 427                                                 "lockd: active RPC handle\n");
 428                                         clnt->cl_dead = 1;
 429                                 } else {
 430                                         rpc_destroy_client(host->h_rpcclnt);
 431                                 }
 432                         }
 433                         kfree(host);
 434                         nrhosts--;
 435                 }
 436         }
 437
 438         next_gc = jiffies + NLM_HOST_COLLECT;
 439 }
 440
 441
 442 /*
 443  * Manage NSM handles
 444  */
 445 static LIST_HEAD(nsm_handles);
 446 static DECLARE_MUTEX(nsm_sema);
 447
 448 static struct nsm_handle *
 449 __nsm_find(const struct sockaddr_in *sin,
 450                 const char *hostname, int hostname_len,
 451                 int create)
 452 {
 453         struct nsm_handle *nsm = NULL;
 454         struct list_head *pos;
 455
 456         if (!sin)
 457                 return NULL;
 458
 459         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 460                 if (printk_ratelimit()) {
 461                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 462                                             "in NFS lock request\n",
 463                                 hostname_len, hostname);
 464                 }
 465                 return NULL;
 466         }
 467
 468         down(&nsm_sema);
 469         list_for_each(pos, &nsm_handles) {
 470                 nsm = list_entry(pos, struct nsm_handle, sm_link);
 471
 472                 if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 473                         continue;
 474                 atomic_inc(&nsm->sm_count);
 475                 goto out;
 476         }
 477
 478         if (!create) {
 479                 nsm = NULL;
 480                 goto out;
 481         }
 482
 483         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
 484         if (nsm != NULL) {
 485                 nsm->sm_addr = *sin;
 486                 nsm->sm_name = (char *) (nsm + 1);
 487                 memcpy(nsm->sm_name, hostname, hostname_len);
 488                 nsm->sm_name[hostname_len] = '\0';
 489                 atomic_set(&nsm->sm_count, 1);
 490
 491                 list_add(&nsm->sm_link, &nsm_handles);
 492         }
 493
 494 out:    up(&nsm_sema);
 495         return nsm;
 496 }
 497
 498 struct nsm_handle *
 499 nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)
 500 {
 501         return __nsm_find(sin, hostname, hostname_len, 1);
 502 }
 503
 504 /*
 505  * Release an NSM handle
 506  */
 507 void
 508 nsm_release(struct nsm_handle *nsm)
 509 {
 510         if (!nsm)
 511                 return;
 512         if (atomic_dec_and_test(&nsm->sm_count)) {
 513                 down(&nsm_sema);
 514                 if (atomic_read(&nsm->sm_count) == 0) {
 515                         list_del(&nsm->sm_link);
 516                         kfree(nsm);
 517                 }
 518                 up(&nsm_sema);
 519         }
 520 }