git.oblomov.eu Git - linux-2.6/blob - 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/module.h>
  10 #include <linux/types.h>
  11 #include <linux/errno.h>
  12 #include <linux/fs.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/utsname.h>
  15 #include <linux/freezer.h>
  16 #include <linux/sunrpc/clnt.h>
  17 #include <linux/sunrpc/svc.h>
  18 #include <linux/lockd/lockd.h>
  19 #include <linux/lockd/sm_inter.h>
  20
  21 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  22 #define NLMCLNT_GRACE_WAIT      (5*HZ)
  23 #define NLMCLNT_POLL_TIMEOUT    (30*HZ)
  24 #define NLMCLNT_MAX_RETRIES     3
  25
  26 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
  27 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
  28 static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
  29 static int      nlm_stat_to_errno(__be32 stat);
  30 static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
  31 static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
  32
  33 static const struct rpc_call_ops nlmclnt_unlock_ops;
  34 static const struct rpc_call_ops nlmclnt_cancel_ops;
  35
  36 /*
  37  * Cookie counter for NLM requests
  38  */
  39 static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
  40
  41 void nlmclnt_next_cookie(struct nlm_cookie *c)
  42 {
  43         u32     cookie = atomic_inc_return(&nlm_cookie);
  44
  45         memcpy(c->data, &cookie, 4);
  46         c->len=4;
  47 }
  48
  49 static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
  50 {
  51         atomic_inc(&lockowner->count);
  52         return lockowner;
  53 }
  54
  55 static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
  56 {
  57         if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
  58                 return;
  59         list_del(&lockowner->list);
  60         spin_unlock(&lockowner->host->h_lock);
  61         nlm_release_host(lockowner->host);
  62         kfree(lockowner);
  63 }
  64
  65 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
  66 {
  67         struct nlm_lockowner *lockowner;
  68         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  69                 if (lockowner->pid == pid)
  70                         return -EBUSY;
  71         }
  72         return 0;
  73 }
  74
  75 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
  76 {
  77         uint32_t res;
  78         do {
  79                 res = host->h_pidcount++;
  80         } while (nlm_pidbusy(host, res) < 0);
  81         return res;
  82 }
  83
  84 static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  85 {
  86         struct nlm_lockowner *lockowner;
  87         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  88                 if (lockowner->owner != owner)
  89                         continue;
  90                 return nlm_get_lockowner(lockowner);
  91         }
  92         return NULL;
  93 }
  94
  95 static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  96 {
  97         struct nlm_lockowner *res, *new = NULL;
  98
  99         spin_lock(&host->h_lock);
 100         res = __nlm_find_lockowner(host, owner);
 101         if (res == NULL) {
 102                 spin_unlock(&host->h_lock);
 103                 new = kmalloc(sizeof(*new), GFP_KERNEL);
 104                 spin_lock(&host->h_lock);
 105                 res = __nlm_find_lockowner(host, owner);
 106                 if (res == NULL && new != NULL) {
 107                         res = new;
 108                         atomic_set(&new->count, 1);
 109                         new->owner = owner;
 110                         new->pid = __nlm_alloc_pid(host);
 111                         new->host = nlm_get_host(host);
 112                         list_add(&new->list, &host->h_lockowners);
 113                         new = NULL;
 114                 }
 115         }
 116         spin_unlock(&host->h_lock);
 117         kfree(new);
 118         return res;
 119 }
 120
 121 /*
 122  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 123  */
 124 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 125 {
 126         struct nlm_args *argp = &req->a_args;
 127         struct nlm_lock *lock = &argp->lock;
 128
 129         nlmclnt_next_cookie(&argp->cookie);
 130         argp->state   = nsm_local_state;
 131         memcpy(&lock->fh, NFS_FH(fl->fl_file->f_path.dentry->d_inode), sizeof(struct nfs_fh));
 132         lock->caller  = utsname()->nodename;
 133         lock->oh.data = req->a_owner;
 134         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
 135                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
 136                                 utsname()->nodename);
 137         lock->svid = fl->fl_u.nfs_fl.owner->pid;
 138         lock->fl.fl_start = fl->fl_start;
 139         lock->fl.fl_end = fl->fl_end;
 140         lock->fl.fl_type = fl->fl_type;
 141 }
 142
 143 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
 144 {
 145         BUG_ON(req->a_args.lock.fl.fl_ops != NULL);
 146 }
 147
 148 /**
 149  * nlmclnt_proc - Perform a single client-side lock request
 150  * @host: address of a valid nlm_host context representing the NLM server
 151  * @cmd: fcntl-style file lock operation to perform
 152  * @fl: address of arguments for the lock operation
 153  *
 154  */
 155 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
 156 {
 157         struct nlm_rqst         *call;
 158         int                     status;
 159
 160         nlm_get_host(host);
 161         call = nlm_alloc_call(host);
 162         if (call == NULL)
 163                 return -ENOMEM;
 164
 165         nlmclnt_locks_init_private(fl, host);
 166         /* Set up the argument struct */
 167         nlmclnt_setlockargs(call, fl);
 168
 169         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 170                 if (fl->fl_type != F_UNLCK) {
 171                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 172                         status = nlmclnt_lock(call, fl);
 173                 } else
 174                         status = nlmclnt_unlock(call, fl);
 175         } else if (IS_GETLK(cmd))
 176                 status = nlmclnt_test(call, fl);
 177         else
 178                 status = -EINVAL;
 179
 180         fl->fl_ops->fl_release_private(fl);
 181         fl->fl_ops = NULL;
 182
 183         dprintk("lockd: clnt proc returns %d\n", status);
 184         return status;
 185 }
 186 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 187
 188 /*
 189  * Allocate an NLM RPC call struct
 190  *
 191  * Note: the caller must hold a reference to host. In case of failure,
 192  * this reference will be released.
 193  */
 194 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 195 {
 196         struct nlm_rqst *call;
 197
 198         for(;;) {
 199                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 200                 if (call != NULL) {
 201                         atomic_set(&call->a_count, 1);
 202                         locks_init_lock(&call->a_args.lock.fl);
 203                         locks_init_lock(&call->a_res.lock.fl);
 204                         call->a_host = host;
 205                         return call;
 206                 }
 207                 if (signalled())
 208                         break;
 209                 printk("nlm_alloc_call: failed, waiting for memory\n");
 210                 schedule_timeout_interruptible(5*HZ);
 211         }
 212         nlm_release_host(host);
 213         return NULL;
 214 }
 215
 216 void nlm_release_call(struct nlm_rqst *call)
 217 {
 218         if (!atomic_dec_and_test(&call->a_count))
 219                 return;
 220         nlm_release_host(call->a_host);
 221         nlmclnt_release_lockargs(call);
 222         kfree(call);
 223 }
 224
 225 static void nlmclnt_rpc_release(void *data)
 226 {
 227         lock_kernel();
 228         nlm_release_call(data);
 229         unlock_kernel();
 230 }
 231
 232 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 233 {
 234         DEFINE_WAIT(wait);
 235         int status = -EINTR;
 236
 237         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 238         if (!signalled ()) {
 239                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 240                 try_to_freeze();
 241                 if (!signalled ())
 242                         status = 0;
 243         }
 244         finish_wait(queue, &wait);
 245         return status;
 246 }
 247
 248 /*
 249  * Generic NLM call
 250  */
 251 static int
 252 nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc)
 253 {
 254         struct nlm_host *host = req->a_host;
 255         struct rpc_clnt *clnt;
 256         struct nlm_args *argp = &req->a_args;
 257         struct nlm_res  *resp = &req->a_res;
 258         struct rpc_message msg = {
 259                 .rpc_argp       = argp,
 260                 .rpc_resp       = resp,
 261                 .rpc_cred       = cred,
 262         };
 263         int             status;
 264
 265         dprintk("lockd: call procedure %d on %s\n",
 266                         (int)proc, host->h_name);
 267
 268         do {
 269                 if (host->h_reclaiming && !argp->reclaim)
 270                         goto in_grace_period;
 271
 272                 /* If we have no RPC client yet, create one. */
 273                 if ((clnt = nlm_bind_host(host)) == NULL)
 274                         return -ENOLCK;
 275                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 276
 277                 /* Perform the RPC call. If an error occurs, try again */
 278                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 279                         dprintk("lockd: rpc_call returned error %d\n", -status);
 280                         switch (status) {
 281                         case -EPROTONOSUPPORT:
 282                                 status = -EINVAL;
 283                                 break;
 284                         case -ECONNREFUSED:
 285                         case -ETIMEDOUT:
 286                         case -ENOTCONN:
 287                                 nlm_rebind_host(host);
 288                                 status = -EAGAIN;
 289                                 break;
 290                         case -ERESTARTSYS:
 291                                 return signalled () ? -EINTR : status;
 292                         default:
 293                                 break;
 294                         }
 295                         break;
 296                 } else
 297                 if (resp->status == nlm_lck_denied_grace_period) {
 298                         dprintk("lockd: server in grace period\n");
 299                         if (argp->reclaim) {
 300                                 printk(KERN_WARNING
 301                                      "lockd: spurious grace period reject?!\n");
 302                                 return -ENOLCK;
 303                         }
 304                 } else {
 305                         if (!argp->reclaim) {
 306                                 /* We appear to be out of the grace period */
 307                                 wake_up_all(&host->h_gracewait);
 308                         }
 309                         dprintk("lockd: server returns status %d\n", resp->status);
 310                         return 0;       /* Okay, call complete */
 311                 }
 312
 313 in_grace_period:
 314                 /*
 315                  * The server has rebooted and appears to be in the grace
 316                  * period during which locks are only allowed to be
 317                  * reclaimed.
 318                  * We can only back off and try again later.
 319                  */
 320                 status = nlm_wait_on_grace(&host->h_gracewait);
 321         } while (status == 0);
 322
 323         return status;
 324 }
 325
 326 /*
 327  * Generic NLM call, async version.
 328  */
 329 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 330 {
 331         struct nlm_host *host = req->a_host;
 332         struct rpc_clnt *clnt;
 333         struct rpc_task_setup task_setup_data = {
 334                 .rpc_message = msg,
 335                 .callback_ops = tk_ops,
 336                 .callback_data = req,
 337                 .flags = RPC_TASK_ASYNC,
 338         };
 339
 340         dprintk("lockd: call procedure %d on %s (async)\n",
 341                         (int)proc, host->h_name);
 342
 343         /* If we have no RPC client yet, create one. */
 344         clnt = nlm_bind_host(host);
 345         if (clnt == NULL)
 346                 goto out_err;
 347         msg->rpc_proc = &clnt->cl_procinfo[proc];
 348         task_setup_data.rpc_client = clnt;
 349
 350         /* bootstrap and kick off the async RPC call */
 351         return rpc_run_task(&task_setup_data);
 352 out_err:
 353         tk_ops->rpc_release(req);
 354         return ERR_PTR(-ENOLCK);
 355 }
 356
 357 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 358 {
 359         struct rpc_task *task;
 360
 361         task = __nlm_async_call(req, proc, msg, tk_ops);
 362         if (IS_ERR(task))
 363                 return PTR_ERR(task);
 364         rpc_put_task(task);
 365         return 0;
 366 }
 367
 368 /*
 369  * NLM asynchronous call.
 370  */
 371 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 372 {
 373         struct rpc_message msg = {
 374                 .rpc_argp       = &req->a_args,
 375                 .rpc_resp       = &req->a_res,
 376         };
 377         return nlm_do_async_call(req, proc, &msg, tk_ops);
 378 }
 379
 380 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 381 {
 382         struct rpc_message msg = {
 383                 .rpc_argp       = &req->a_res,
 384         };
 385         return nlm_do_async_call(req, proc, &msg, tk_ops);
 386 }
 387
 388 /*
 389  * NLM client asynchronous call.
 390  *
 391  * Note that although the calls are asynchronous, and are therefore
 392  *      guaranteed to complete, we still always attempt to wait for
 393  *      completion in order to be able to correctly track the lock
 394  *      state.
 395  */
 396 static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 397 {
 398         struct rpc_message msg = {
 399                 .rpc_argp       = &req->a_args,
 400                 .rpc_resp       = &req->a_res,
 401                 .rpc_cred       = cred,
 402         };
 403         struct rpc_task *task;
 404         int err;
 405
 406         task = __nlm_async_call(req, proc, &msg, tk_ops);
 407         if (IS_ERR(task))
 408                 return PTR_ERR(task);
 409         err = rpc_wait_for_completion_task(task);
 410         rpc_put_task(task);
 411         return err;
 412 }
 413
 414 /*
 415  * TEST for the presence of a conflicting lock
 416  */
 417 static int
 418 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 419 {
 420         int     status;
 421
 422         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 423         if (status < 0)
 424                 goto out;
 425
 426         switch (req->a_res.status) {
 427                 case nlm_granted:
 428                         fl->fl_type = F_UNLCK;
 429                         break;
 430                 case nlm_lck_denied:
 431                         /*
 432                          * Report the conflicting lock back to the application.
 433                          */
 434                         fl->fl_start = req->a_res.lock.fl.fl_start;
 435                         fl->fl_end = req->a_res.lock.fl.fl_end;
 436                         fl->fl_type = req->a_res.lock.fl.fl_type;
 437                         fl->fl_pid = 0;
 438                         break;
 439                 default:
 440                         status = nlm_stat_to_errno(req->a_res.status);
 441         }
 442 out:
 443         nlm_release_call(req);
 444         return status;
 445 }
 446
 447 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 448 {
 449         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 450         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
 451         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 452 }
 453
 454 static void nlmclnt_locks_release_private(struct file_lock *fl)
 455 {
 456         list_del(&fl->fl_u.nfs_fl.list);
 457         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 458 }
 459
 460 static struct file_lock_operations nlmclnt_lock_ops = {
 461         .fl_copy_lock = nlmclnt_locks_copy_lock,
 462         .fl_release_private = nlmclnt_locks_release_private,
 463 };
 464
 465 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 466 {
 467         BUG_ON(fl->fl_ops != NULL);
 468         fl->fl_u.nfs_fl.state = 0;
 469         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 470         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 471         fl->fl_ops = &nlmclnt_lock_ops;
 472 }
 473
 474 static int do_vfs_lock(struct file_lock *fl)
 475 {
 476         int res = 0;
 477         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
 478                 case FL_POSIX:
 479                         res = posix_lock_file_wait(fl->fl_file, fl);
 480                         break;
 481                 case FL_FLOCK:
 482                         res = flock_lock_file_wait(fl->fl_file, fl);
 483                         break;
 484                 default:
 485                         BUG();
 486         }
 487         return res;
 488 }
 489
 490 /*
 491  * LOCK: Try to create a lock
 492  *
 493  *                      Programmer Harassment Alert
 494  *
 495  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 496  * will faithfully return LCK_BLOCKED but never cares to notify us when
 497  * the lock could be granted. This way, our local process could hang
 498  * around forever waiting for the callback.
 499  *
 500  *  Solution A: Implement busy-waiting
 501  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 502  *
 503  * For now I am implementing solution A, because I hate the idea of
 504  * re-implementing lockd for a third time in two months. The async
 505  * calls shouldn't be too hard to do, however.
 506  *
 507  * This is one of the lovely things about standards in the NFS area:
 508  * they're so soft and squishy you can't really blame HP for doing this.
 509  */
 510 static int
 511 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 512 {
 513         struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
 514         struct nlm_host *host = req->a_host;
 515         struct nlm_res  *resp = &req->a_res;
 516         struct nlm_wait *block = NULL;
 517         unsigned char fl_flags = fl->fl_flags;
 518         unsigned char fl_type;
 519         int status = -ENOLCK;
 520
 521         if (nsm_monitor(host) < 0) {
 522                 printk(KERN_NOTICE "lockd: failed to monitor %s\n",
 523                                         host->h_name);
 524                 goto out;
 525         }
 526         fl->fl_flags |= FL_ACCESS;
 527         status = do_vfs_lock(fl);
 528         fl->fl_flags = fl_flags;
 529         if (status < 0)
 530                 goto out;
 531
 532         block = nlmclnt_prepare_block(host, fl);
 533 again:
 534         /*
 535          * Initialise resp->status to a valid non-zero value,
 536          * since 0 == nlm_lck_granted
 537          */
 538         resp->status = nlm_lck_blocked;
 539         for(;;) {
 540                 /* Reboot protection */
 541                 fl->fl_u.nfs_fl.state = host->h_state;
 542                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 543                 if (status < 0)
 544                         break;
 545                 /* Did a reclaimer thread notify us of a server reboot? */
 546                 if (resp->status ==  nlm_lck_denied_grace_period)
 547                         continue;
 548                 if (resp->status != nlm_lck_blocked)
 549                         break;
 550                 /* Wait on an NLM blocking lock */
 551                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 552                 if (status < 0)
 553                         break;
 554                 if (resp->status != nlm_lck_blocked)
 555                         break;
 556         }
 557
 558         /* if we were interrupted while blocking, then cancel the lock request
 559          * and exit
 560          */
 561         if (resp->status == nlm_lck_blocked) {
 562                 if (!req->a_args.block)
 563                         goto out_unlock;
 564                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 565                         goto out_unblock;
 566         }
 567
 568         if (resp->status == nlm_granted) {
 569                 down_read(&host->h_rwsem);
 570                 /* Check whether or not the server has rebooted */
 571                 if (fl->fl_u.nfs_fl.state != host->h_state) {
 572                         up_read(&host->h_rwsem);
 573                         goto again;
 574                 }
 575                 /* Ensure the resulting lock will get added to granted list */
 576                 fl->fl_flags |= FL_SLEEP;
 577                 if (do_vfs_lock(fl) < 0)
 578                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 579                 up_read(&host->h_rwsem);
 580                 fl->fl_flags = fl_flags;
 581                 status = 0;
 582         }
 583         if (status < 0)
 584                 goto out_unlock;
 585         status = nlm_stat_to_errno(resp->status);
 586 out_unblock:
 587         nlmclnt_finish_block(block);
 588 out:
 589         nlm_release_call(req);
 590         return status;
 591 out_unlock:
 592         /* Fatal error: ensure that we remove the lock altogether */
 593         dprintk("lockd: lock attempt ended in fatal error.\n"
 594                 "       Attempting to unlock.\n");
 595         nlmclnt_finish_block(block);
 596         fl_type = fl->fl_type;
 597         fl->fl_type = F_UNLCK;
 598         down_read(&host->h_rwsem);
 599         do_vfs_lock(fl);
 600         up_read(&host->h_rwsem);
 601         fl->fl_type = fl_type;
 602         fl->fl_flags = fl_flags;
 603         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 604         return status;
 605 }
 606
 607 /*
 608  * RECLAIM: Try to reclaim a lock
 609  */
 610 int
 611 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
 612 {
 613         struct nlm_rqst reqst, *req;
 614         int             status;
 615
 616         req = &reqst;
 617         memset(req, 0, sizeof(*req));
 618         locks_init_lock(&req->a_args.lock.fl);
 619         locks_init_lock(&req->a_res.lock.fl);
 620         req->a_host  = host;
 621         req->a_flags = 0;
 622
 623         /* Set up the argument struct */
 624         nlmclnt_setlockargs(req, fl);
 625         req->a_args.reclaim = 1;
 626
 627         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 628         if (status >= 0 && req->a_res.status == nlm_granted)
 629                 return 0;
 630
 631         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 632                                 "(errno %d, status %d)\n", fl->fl_pid,
 633                                 status, ntohl(req->a_res.status));
 634
 635         /*
 636          * FIXME: This is a serious failure. We can
 637          *
 638          *  a.  Ignore the problem
 639          *  b.  Send the owning process some signal (Linux doesn't have
 640          *      SIGLOST, though...)
 641          *  c.  Retry the operation
 642          *
 643          * Until someone comes up with a simple implementation
 644          * for b or c, I'll choose option a.
 645          */
 646
 647         return -ENOLCK;
 648 }
 649
 650 /*
 651  * UNLOCK: remove an existing lock
 652  */
 653 static int
 654 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 655 {
 656         struct nlm_host *host = req->a_host;
 657         struct nlm_res  *resp = &req->a_res;
 658         int status;
 659         unsigned char fl_flags = fl->fl_flags;
 660
 661         /*
 662          * Note: the server is supposed to either grant us the unlock
 663          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 664          * case, we want to unlock.
 665          */
 666         fl->fl_flags |= FL_EXISTS;
 667         down_read(&host->h_rwsem);
 668         status = do_vfs_lock(fl);
 669         up_read(&host->h_rwsem);
 670         fl->fl_flags = fl_flags;
 671         if (status == -ENOENT) {
 672                 status = 0;
 673                 goto out;
 674         }
 675
 676         atomic_inc(&req->a_count);
 677         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 678                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 679         if (status < 0)
 680                 goto out;
 681
 682         if (resp->status == nlm_granted)
 683                 goto out;
 684
 685         if (resp->status != nlm_lck_denied_nolocks)
 686                 printk("lockd: unexpected unlock status: %d\n", resp->status);
 687         /* What to do now? I'm out of my depth... */
 688         status = -ENOLCK;
 689 out:
 690         nlm_release_call(req);
 691         return status;
 692 }
 693
 694 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 695 {
 696         struct nlm_rqst *req = data;
 697         u32 status = ntohl(req->a_res.status);
 698
 699         if (RPC_ASSASSINATED(task))
 700                 goto die;
 701
 702         if (task->tk_status < 0) {
 703                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 704                 goto retry_rebind;
 705         }
 706         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 707                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 708                 goto retry_unlock;
 709         }
 710         if (status != NLM_LCK_GRANTED)
 711                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 712 die:
 713         return;
 714  retry_rebind:
 715         lock_kernel();
 716         nlm_rebind_host(req->a_host);
 717         unlock_kernel();
 718  retry_unlock:
 719         rpc_restart_call(task);
 720 }
 721
 722 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 723         .rpc_call_done = nlmclnt_unlock_callback,
 724         .rpc_release = nlmclnt_rpc_release,
 725 };
 726
 727 /*
 728  * Cancel a blocked lock request.
 729  * We always use an async RPC call for this in order not to hang a
 730  * process that has been Ctrl-C'ed.
 731  */
 732 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 733 {
 734         struct nlm_rqst *req;
 735         int status;
 736
 737         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 738                 "       Attempting to cancel lock.\n");
 739
 740         req = nlm_alloc_call(nlm_get_host(host));
 741         if (!req)
 742                 return -ENOMEM;
 743         req->a_flags = RPC_TASK_ASYNC;
 744
 745         nlmclnt_setlockargs(req, fl);
 746         req->a_args.block = block;
 747
 748         atomic_inc(&req->a_count);
 749         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 750                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 751         if (status == 0 && req->a_res.status == nlm_lck_denied)
 752                 status = -ENOLCK;
 753         nlm_release_call(req);
 754         return status;
 755 }
 756
 757 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 758 {
 759         struct nlm_rqst *req = data;
 760         u32 status = ntohl(req->a_res.status);
 761
 762         if (RPC_ASSASSINATED(task))
 763                 goto die;
 764
 765         if (task->tk_status < 0) {
 766                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 767                                         task->tk_status);
 768                 goto retry_cancel;
 769         }
 770
 771         dprintk("lockd: cancel status %u (task %u)\n",
 772                         status, task->tk_pid);
 773
 774         switch (status) {
 775         case NLM_LCK_GRANTED:
 776         case NLM_LCK_DENIED_GRACE_PERIOD:
 777         case NLM_LCK_DENIED:
 778                 /* Everything's good */
 779                 break;
 780         case NLM_LCK_DENIED_NOLOCKS:
 781                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 782                 goto retry_cancel;
 783         default:
 784                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 785                         status);
 786         }
 787
 788 die:
 789         return;
 790
 791 retry_cancel:
 792         /* Don't ever retry more than 3 times */
 793         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 794                 goto die;
 795         lock_kernel();
 796         nlm_rebind_host(req->a_host);
 797         unlock_kernel();
 798         rpc_restart_call(task);
 799         rpc_delay(task, 30 * HZ);
 800 }
 801
 802 static const struct rpc_call_ops nlmclnt_cancel_ops = {
 803         .rpc_call_done = nlmclnt_cancel_callback,
 804         .rpc_release = nlmclnt_rpc_release,
 805 };
 806
 807 /*
 808  * Convert an NLM status code to a generic kernel errno
 809  */
 810 static int
 811 nlm_stat_to_errno(__be32 status)
 812 {
 813         switch(ntohl(status)) {
 814         case NLM_LCK_GRANTED:
 815                 return 0;
 816         case NLM_LCK_DENIED:
 817                 return -EAGAIN;
 818         case NLM_LCK_DENIED_NOLOCKS:
 819         case NLM_LCK_DENIED_GRACE_PERIOD:
 820                 return -ENOLCK;
 821         case NLM_LCK_BLOCKED:
 822                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 823                 return -ENOLCK;
 824 #ifdef CONFIG_LOCKD_V4
 825         case NLM_DEADLCK:
 826                 return -EDEADLK;
 827         case NLM_ROFS:
 828                 return -EROFS;
 829         case NLM_STALE_FH:
 830                 return -ESTALE;
 831         case NLM_FBIG:
 832                 return -EOVERFLOW;
 833         case NLM_FAILED:
 834                 return -ENOLCK;
 835 #endif
 836         }
 837         printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
 838         return -ENOLCK;
 839 }