fs/lockd/clntproc.c

   1 /*
   2  * linux/fs/lockd/clntproc.c
   3  *
   4  * RPC procedures for the client side NLM implementation
   5  *
   6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/errno.h>
  11 #include <linux/fs.h>
  12 #include <linux/nfs_fs.h>
  13 #include <linux/utsname.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
  19 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  20
  21 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
  22 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
  23 static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
  24 static void     nlmclnt_unlock_callback(struct rpc_task *);
  25 static void     nlmclnt_cancel_callback(struct rpc_task *);
  26 static int      nlm_stat_to_errno(u32 stat);
  27
  28 /*
  29  * Cookie counter for NLM requests
  30  */
  31 static u32      nlm_cookie = 0x1234;
  32
  33 /*
  34  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
  35  */
  36 static inline void
  37 nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
  38 {
  39         struct nlm_args *argp = &req->a_args;
  40         struct nlm_lock *lock = &argp->lock;
  41
  42         memset(argp, 0, sizeof(*argp));
  43         argp->cookie  = nlm_cookie++;
  44         argp->state   = nsm_local_state;
  45         lock->fh      = *NFS_FH(fl->fl_file->f_dentry);
  46         lock->caller  = system_utsname.nodename;
  47         lock->oh.data = req->a_owner;
  48         lock->oh.len  = sprintf(req->a_owner, "%d@%s",
  49                                 current->pid, system_utsname.nodename);
  50         lock->fl      = *fl;
  51 }
  52
  53 /*
  54  * Initialize arguments for GRANTED call. The nlm_rqst structure
  55  * has been cleared already.
  56  */
  57 int
  58 nlmclnt_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
  59 {
  60         call->a_args.cookie  = nlm_cookie++;
  61         call->a_args.lock    = *lock;
  62         call->a_args.lock.caller = system_utsname.nodename;
  63
  64         /* set default data area */
  65         call->a_args.lock.oh.data = call->a_owner;
  66
  67         if (lock->oh.len > NLMCLNT_OHSIZE) {
  68                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
  69                 if (!data)
  70                         return 0;
  71                 call->a_args.lock.oh.data = (u8 *) data;
  72         }
  73
  74         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
  75         return 1;
  76 }
  77
  78 void
  79 nlmclnt_freegrantargs(struct nlm_rqst *call)
  80 {
  81         /*
  82          * Check whether we allocated memory for the owner.
  83          */
  84         if (call->a_args.lock.oh.data != (u8 *) call->a_owner) {
  85                 kfree(call->a_args.lock.oh.data);
  86         }
  87 }
  88
  89 /*
  90  * This is the main entry point for the NLM client.
  91  */
  92 int
  93 nlmclnt_proc(struct inode *inode, int cmd, struct file_lock *fl)
  94 {
  95         struct nfs_server       *nfssrv = NFS_SERVER(inode);
  96         struct nlm_host         *host;
  97         struct nlm_rqst         reqst, *call = &reqst;
  98         sigset_t                oldset;
  99         unsigned long           flags;
 100         int                     status;
 101
 102         /* Always use NLM version 1 over UDP for now... */
 103         if (!(host = nlmclnt_lookup_host(NFS_ADDR(inode), IPPROTO_UDP, 1)))
 104                 return -ENOLCK;
 105
 106         /* Create RPC client handle if not there, and copy soft
 107          * and intr flags from NFS client. */
 108         if (host->h_rpcclnt == NULL) {
 109                 struct rpc_clnt *clnt;
 110
 111                 /* Bind an rpc client to this host handle (does not
 112                  * perform a portmapper lookup) */
 113                 if (!(clnt = nlm_bind_host(host))) {
 114                         status = -ENOLCK;
 115                         goto done;
 116                 }
 117                 clnt->cl_softrtry = nfssrv->client->cl_softrtry;
 118                 clnt->cl_intr     = nfssrv->client->cl_intr;
 119                 clnt->cl_chatty   = nfssrv->client->cl_chatty;
 120         }
 121
 122         /* Keep the old signal mask */
 123         spin_lock_irqsave(&current->sigmask_lock, flags);
 124         oldset = current->blocked;
 125
 126         /* If we're cleaning up locks because the process is exiting,
 127          * perform the RPC call asynchronously. */
 128         if (cmd == F_SETLK && fl->fl_type == F_UNLCK
 129             && (current->flags & PF_EXITING)) {
 130                 sigfillset(&current->blocked);  /* Mask all signals */
 131                 recalc_sigpending(current);
 132                 spin_unlock_irqrestore(&current->sigmask_lock, flags);
 133
 134                 call = nlmclnt_alloc_call();
 135                 call->a_flags = RPC_TASK_ASYNC;
 136         } else {
 137                 spin_unlock_irqrestore(&current->sigmask_lock, flags);
 138                 call->a_flags = 0;
 139         }
 140         call->a_host = host;
 141
 142         /* Set up the argument struct */
 143         nlmclnt_setlockargs(call, fl);
 144
 145         if (cmd == F_GETLK) {
 146                 status = nlmclnt_test(call, fl);
 147         } else if (cmd == F_SETLK && fl->fl_type == F_UNLCK) {
 148                 status = nlmclnt_unlock(call, fl);
 149         } else if (cmd == F_SETLK || cmd == F_SETLKW) {
 150                 call->a_args.block = (cmd == F_SETLKW)? 1 : 0;
 151                 status = nlmclnt_lock(call, fl);
 152         } else {
 153                 status = -EINVAL;
 154         }
 155
 156         if (status < 0 && (call->a_flags & RPC_TASK_ASYNC))
 157                 rpc_free(call);
 158
 159         spin_lock_irqsave(&current->sigmask_lock, flags);
 160         current->blocked = oldset;
 161         recalc_sigpending(current);
 162         spin_unlock_irqrestore(&current->sigmask_lock, flags);
 163
 164 done:
 165         dprintk("lockd: clnt proc returns %d\n", status);
 166         nlm_release_host(host);
 167         return status;
 168 }
 169
 170 /*
 171  * Wait while server is in grace period
 172  */
 173 static inline int
 174 nlmclnt_grace_wait(struct nlm_host *host)
 175 {
 176         if (!host->h_reclaiming)
 177                 current->timeout = jiffies + 10 * HZ;
 178         interruptible_sleep_on(&host->h_gracewait);
 179         current->timeout = 0;
 180         return signalled()? -ERESTARTSYS : 0;
 181 }
 182
 183 /*
 184  * Allocate an NLM RPC call struct
 185  */
 186 struct nlm_rqst *
 187 nlmclnt_alloc_call(void)
 188 {
 189         struct nlm_rqst *call;
 190
 191         while (!signalled()) {
 192                 call = (struct nlm_rqst *) rpc_allocate(RPC_TASK_ASYNC,
 193                                         sizeof(struct nlm_rqst));
 194                 if (call)
 195                         return call;
 196                 printk("nlmclnt_alloc_call: failed, waiting for memory\n");
 197                 current->timeout = jiffies + 5 * HZ;
 198                 current->state = TASK_INTERRUPTIBLE;
 199                 schedule();
 200                 current->timeout = 0;
 201         }
 202         return NULL;
 203 }
 204
 205 /*
 206  * Generic NLM call
 207  */
 208 int
 209 nlmclnt_call(struct nlm_rqst *req, u32 proc)
 210 {
 211         struct nlm_host *host = req->a_host;
 212         struct rpc_clnt *clnt;
 213         struct nlm_args *argp = &req->a_args;
 214         struct nlm_res  *resp = &req->a_res;
 215         int             status;
 216
 217         dprintk("lockd: call procedure %s on %s\n",
 218                         nlm_procname(proc), host->h_name);
 219
 220         do {
 221                 if (host->h_reclaiming && !argp->reclaim) {
 222                         interruptible_sleep_on(&host->h_gracewait);
 223                         continue;
 224                 }
 225
 226                 /* If we have no RPC client yet, create one. */
 227                 if ((clnt = nlm_bind_host(host)) == NULL)
 228                         return -ENOLCK;
 229
 230                 /* Perform the RPC call. If an error occurs, try again */
 231                 if ((status = rpc_call(clnt, proc, argp, resp, 0)) < 0) {
 232                         dprintk("lockd: rpc_call returned error %d\n", -status);
 233                         if (status == -ERESTARTSYS)
 234                                 return status;
 235                         nlm_rebind_host(host);
 236                 } else
 237                 if (resp->status == NLM_LCK_DENIED_GRACE_PERIOD) {
 238                         dprintk("lockd: server in grace period\n");
 239                         if (argp->reclaim) {
 240                                 printk(KERN_WARNING
 241                                      "lockd: spurious grace period reject?!\n");
 242                                 return -ENOLCK;
 243                         }
 244                 } else {
 245                         dprintk("lockd: server returns status %d\n", resp->status);
 246                         return 0;       /* Okay, call complete */
 247                 }
 248
 249                 /* Back off a little and try again */
 250                 current->timeout = jiffies + 15 * HZ;
 251                 interruptible_sleep_on(&host->h_gracewait);
 252                 current->timeout = 0;
 253         } while (!signalled());
 254
 255         return -ERESTARTSYS;
 256 }
 257
 258 /*
 259  * Generic NLM call, async version.
 260  */
 261 int
 262 nlmclnt_async_call(struct nlm_rqst *req, u32 proc, rpc_action callback)
 263 {
 264         struct nlm_host *host = req->a_host;
 265         struct rpc_clnt *clnt;
 266         struct nlm_args *argp = &req->a_args;
 267         struct nlm_res  *resp = &req->a_res;
 268         int             status;
 269
 270         dprintk("lockd: call procedure %s on %s (async)\n",
 271                         nlm_procname(proc), host->h_name);
 272
 273         /* If we have no RPC client yet, create one. */
 274         if ((clnt = nlm_bind_host(host)) == NULL)
 275                 return -ENOLCK;
 276
 277         /* bootstrap and kick off the async RPC call */
 278         status = rpc_do_call(clnt, proc, argp, resp, RPC_TASK_ASYNC,
 279                                         callback, req);
 280
 281         /* If the async call is proceeding, increment host refcount */
 282         if (status >= 0 && (req->a_flags & RPC_TASK_ASYNC))
 283                 host->h_count++;
 284         return status;
 285 }
 286
 287 /*
 288  * TEST for the presence of a conflicting lock
 289  */
 290 static int
 291 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 292 {
 293         int     status;
 294
 295         if ((status = nlmclnt_call(req, NLMPROC_TEST)) < 0)
 296                 return status;
 297
 298         status = req->a_res.status;
 299         if (status == NLM_LCK_GRANTED) {
 300                 fl->fl_type = F_UNLCK;
 301         } if (status == NLM_LCK_DENIED) {
 302                 /*
 303                  * Report the conflicting lock back to the application.
 304                  * FIXME: Is it OK to report the pid back as well?
 305                  */
 306                 memcpy(fl, &req->a_res.lock.fl, sizeof(*fl));
 307                 /* fl->fl_pid = 0; */
 308         } else {
 309                 return nlm_stat_to_errno(req->a_res.status);
 310         }
 311
 312         return 0;
 313 }
 314
 315 /*
 316  * LOCK: Try to create a lock
 317  *
 318  *                      Programmer Harassment Alert
 319  *
 320  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 321  * will faithfully return LCK_BLOCKED but never cares to notify us when
 322  * the lock could be granted. This way, our local process could hang
 323  * around forever waiting for the callback.
 324  *
 325  *  Solution A: Implement busy-waiting
 326  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 327  *
 328  * For now I am implementing solution A, because I hate the idea of
 329  * re-implementing lockd for a third time in two months. The async
 330  * calls shouldn't be too hard to do, however.
 331  *
 332  * This is one of the lovely things about standards in the NFS area:
 333  * they're so soft and squishy you can't really blame HP for doing this.
 334  */
 335 static int
 336 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 337 {
 338         struct nlm_host *host = req->a_host;
 339         struct nlm_res  *resp = &req->a_res;
 340         int             status;
 341
 342         if (!host->h_monitored && nsm_monitor(host) < 0) {
 343                 printk(KERN_NOTICE "lockd: failed to monitor %s\n",
 344                                         host->h_name);
 345                 return -ENOLCK;
 346         }
 347
 348         while (1) {
 349                 if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0) {
 350                         if (resp->status != NLM_LCK_BLOCKED)
 351                                 break;
 352                         status = nlmclnt_block(host, fl, &resp->status);
 353                 }
 354                 if (status < 0)
 355                         return status;
 356         }
 357
 358         if (resp->status == NLM_LCK_GRANTED) {
 359                 fl->fl_u.nfs_fl.state = host->h_state;
 360                 fl->fl_u.nfs_fl.flags |= NFS_LCK_GRANTED;
 361         }
 362
 363         return nlm_stat_to_errno(resp->status);
 364 }
 365
 366 /*
 367  * RECLAIM: Try to reclaim a lock
 368  */
 369 int
 370 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
 371 {
 372         struct nlm_rqst reqst, *req;
 373         int             status;
 374
 375         req = &reqst;
 376         req->a_host  = host;
 377         req->a_flags = 0;
 378
 379         /* Set up the argument struct */
 380         nlmclnt_setlockargs(req, fl);
 381         req->a_args.reclaim = 1;
 382
 383         if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0
 384          && req->a_res.status == NLM_LCK_GRANTED)
 385                 return 0;
 386
 387         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 388                                 "(errno %d, status %d)\n", fl->fl_pid,
 389                                 status, req->a_res.status);
 390
 391         /*
 392          * FIXME: This is a serious failure. We can
 393          *
 394          *  a.  Ignore the problem
 395          *  b.  Send the owning process some signal (Linux doesn't have
 396          *      SIGLOST, though...)
 397          *  c.  Retry the operation
 398          *
 399          * Until someone comes up with a simple implementation
 400          * for b or c, I'll choose option a.
 401          */
 402
 403         return -ENOLCK;
 404 }
 405
 406 /*
 407  * UNLOCK: remove an existing lock
 408  */
 409 static int
 410 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 411 {
 412         struct nlm_host *host = req->a_host;
 413         struct nlm_res  *resp = &req->a_res;
 414         int             status;
 415
 416         /* No monitor, no lock: see nlmclnt_lock().
 417          * Since this is an UNLOCK, don't try to setup monitoring here. */
 418         if (!host->h_monitored)
 419                 return -ENOLCK;
 420
 421         /* Clean the GRANTED flag now so the lock doesn't get
 422          * reclaimed while we're stuck in the unlock call. */
 423         fl->fl_u.nfs_fl.flags &= ~NFS_LCK_GRANTED;
 424
 425         if (req->a_flags & RPC_TASK_ASYNC) {
 426                 return nlmclnt_async_call(req, NLMPROC_UNLOCK,
 427                                         nlmclnt_unlock_callback);
 428         }
 429
 430         if ((status = nlmclnt_call(req, NLMPROC_UNLOCK)) < 0)
 431                 return status;
 432
 433         if (resp->status == NLM_LCK_GRANTED)
 434                 return 0;
 435
 436         if (resp->status != NLM_LCK_DENIED_NOLOCKS)
 437                 printk("lockd: unexpected unlock status: %d\n", resp->status);
 438
 439         /* What to do now? I'm out of my depth... */
 440
 441         return -ENOLCK;
 442 }
 443
 444 static void
 445 nlmclnt_unlock_callback(struct rpc_task *task)
 446 {
 447         struct nlm_rqst *req = (struct nlm_rqst *) task->tk_calldata;
 448         int             status = req->a_res.status;
 449
 450         if (RPC_ASSASSINATED(task))
 451                 goto die;
 452
 453         if (task->tk_status < 0) {
 454                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 455                 nlm_rebind_host(req->a_host);
 456                 rpc_restart_call(task);
 457                 return;
 458         }
 459         if (status != NLM_LCK_GRANTED
 460          && status != NLM_LCK_DENIED_GRACE_PERIOD) {
 461                 printk("lockd: unexpected unlock status: %d\n", status);
 462         }
 463
 464 die:
 465         rpc_release_task(task);
 466 }
 467
 468 /*
 469  * Cancel a blocked lock request.
 470  * We always use an async RPC call for this in order not to hang a
 471  * process that has been Ctrl-C'ed.
 472  */
 473 int
 474 nlmclnt_cancel(struct nlm_host *host, struct file_lock *fl)
 475 {
 476         struct nlm_rqst *req;
 477         unsigned long   flags;
 478         sigset_t        oldset;
 479         int             status;
 480
 481         /* Block all signals while setting up call */
 482         spin_lock_irqsave(&current->sigmask_lock, flags);
 483         oldset = current->blocked;
 484         sigfillset(&current->blocked);
 485         recalc_sigpending(current);
 486         spin_unlock_irqrestore(&current->sigmask_lock, flags);
 487
 488         do {
 489                 req = (struct nlm_rqst *) rpc_allocate(RPC_TASK_ASYNC,
 490                                                         sizeof(*req));
 491         } while (req == NULL);
 492         req->a_host  = host;
 493         req->a_flags = RPC_TASK_ASYNC;
 494
 495         nlmclnt_setlockargs(req, fl);
 496
 497         status = nlmclnt_async_call(req, NLMPROC_CANCEL,
 498                                         nlmclnt_cancel_callback);
 499         if (status < 0)
 500                 rpc_free(req);
 501
 502         spin_lock_irqsave(&current->sigmask_lock, flags);
 503         current->blocked = oldset;
 504         recalc_sigpending(current);
 505         spin_unlock_irqrestore(&current->sigmask_lock, flags);
 506
 507         return status;
 508 }
 509
 510 static void
 511 nlmclnt_cancel_callback(struct rpc_task *task)
 512 {
 513         struct nlm_rqst *req = (struct nlm_rqst *) task->tk_calldata;
 514
 515         if (RPC_ASSASSINATED(task))
 516                 goto die;
 517
 518         if (task->tk_status < 0) {
 519                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 520                                         task->tk_status);
 521                 goto retry_cancel;
 522         }
 523
 524         dprintk("lockd: cancel status %d (task %d)\n",
 525                         req->a_res.status, task->tk_pid);
 526
 527         switch (req->a_res.status) {
 528         case NLM_LCK_GRANTED:
 529         case NLM_LCK_DENIED_GRACE_PERIOD:
 530                 /* Everything's good */
 531                 break;
 532         case NLM_LCK_DENIED_NOLOCKS:
 533                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 534                 goto retry_cancel;
 535         default:
 536                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 537                         req->a_res.status);
 538         }
 539
 540 die:
 541         rpc_release_task(task);
 542         nlm_release_host(req->a_host);
 543         kfree(req);
 544         return;
 545
 546 retry_cancel:
 547         nlm_rebind_host(req->a_host);
 548         rpc_restart_call(task);
 549         rpc_delay(task, 30 * HZ);
 550         return;
 551 }
 552
 553 /*
 554  * Convert an NLM status code to a generic kernel errno
 555  */
 556 static int
 557 nlm_stat_to_errno(u32 status)
 558 {
 559         switch(status) {
 560         case NLM_LCK_GRANTED:
 561                 return 0;
 562         case NLM_LCK_DENIED:
 563                 return -EAGAIN;
 564         case NLM_LCK_DENIED_NOLOCKS:
 565         case NLM_LCK_DENIED_GRACE_PERIOD:
 566                 return -ENOLCK;
 567         case NLM_LCK_BLOCKED:
 568                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 569                 return -ENOLCK;
 570         }
 571         printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
 572         return -ENOLCK;
 573 }