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
  20 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  21 #define NLMCLNT_GRACE_WAIT      (5*HZ)
  22 #define NLMCLNT_POLL_TIMEOUT    (30*HZ)
  23 #define NLMCLNT_MAX_RETRIES     3
  24
  25 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
  26 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
  27 static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
  28 static int      nlm_stat_to_errno(__be32 stat);
  29 static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
  30 static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
  31
  32 static const struct rpc_call_ops nlmclnt_unlock_ops;
  33 static const struct rpc_call_ops nlmclnt_cancel_ops;
  34
  35 /*
  36  * Cookie counter for NLM requests
  37  */
  38 static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
  39
  40 void nlmclnt_next_cookie(struct nlm_cookie *c)
  41 {
  42         u32     cookie = atomic_inc_return(&nlm_cookie);
  43
  44         memcpy(c->data, &cookie, 4);
  45         c->len=4;
  46 }
  47
  48 static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
  49 {
  50         atomic_inc(&lockowner->count);
  51         return lockowner;
  52 }
  53
  54 static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
  55 {
  56         if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
  57                 return;
  58         list_del(&lockowner->list);
  59         spin_unlock(&lockowner->host->h_lock);
  60         nlm_release_host(lockowner->host);
  61         kfree(lockowner);
  62 }
  63
  64 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
  65 {
  66         struct nlm_lockowner *lockowner;
  67         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  68                 if (lockowner->pid == pid)
  69                         return -EBUSY;
  70         }
  71         return 0;
  72 }
  73
  74 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
  75 {
  76         uint32_t res;
  77         do {
  78                 res = host->h_pidcount++;
  79         } while (nlm_pidbusy(host, res) < 0);
  80         return res;
  81 }
  82
  83 static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  84 {
  85         struct nlm_lockowner *lockowner;
  86         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  87                 if (lockowner->owner != owner)
  88                         continue;
  89                 return nlm_get_lockowner(lockowner);
  90         }
  91         return NULL;
  92 }
  93
  94 static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  95 {
  96         struct nlm_lockowner *res, *new = NULL;
  97
  98         spin_lock(&host->h_lock);
  99         res = __nlm_find_lockowner(host, owner);
 100         if (res == NULL) {
 101                 spin_unlock(&host->h_lock);
 102                 new = kmalloc(sizeof(*new), GFP_KERNEL);
 103                 spin_lock(&host->h_lock);
 104                 res = __nlm_find_lockowner(host, owner);
 105                 if (res == NULL && new != NULL) {
 106                         res = new;
 107                         atomic_set(&new->count, 1);
 108                         new->owner = owner;
 109                         new->pid = __nlm_alloc_pid(host);
 110                         new->host = nlm_get_host(host);
 111                         list_add(&new->list, &host->h_lockowners);
 112                         new = NULL;
 113                 }
 114         }
 115         spin_unlock(&host->h_lock);
 116         kfree(new);
 117         return res;
 118 }
 119
 120 /*
 121  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 122  */
 123 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 124 {
 125         struct nlm_args *argp = &req->a_args;
 126         struct nlm_lock *lock = &argp->lock;
 127
 128         nlmclnt_next_cookie(&argp->cookie);
 129         argp->state   = nsm_local_state;
 130         memcpy(&lock->fh, NFS_FH(fl->fl_file->f_path.dentry->d_inode), sizeof(struct nfs_fh));
 131         lock->caller  = utsname()->nodename;
 132         lock->oh.data = req->a_owner;
 133         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
 134                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
 135                                 utsname()->nodename);
 136         lock->svid = fl->fl_u.nfs_fl.owner->pid;
 137         lock->fl.fl_start = fl->fl_start;
 138         lock->fl.fl_end = fl->fl_end;
 139         lock->fl.fl_type = fl->fl_type;
 140 }
 141
 142 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
 143 {
 144         BUG_ON(req->a_args.lock.fl.fl_ops != NULL);
 145 }
 146
 147 /**
 148  * nlmclnt_proc - Perform a single client-side lock request
 149  * @host: address of a valid nlm_host context representing the NLM server
 150  * @cmd: fcntl-style file lock operation to perform
 151  * @fl: address of arguments for the lock operation
 152  *
 153  */
 154 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
 155 {
 156         struct nlm_rqst         *call;
 157         int                     status;
 158
 159         nlm_get_host(host);
 160         call = nlm_alloc_call(host);
 161         if (call == NULL)
 162                 return -ENOMEM;
 163
 164         nlmclnt_locks_init_private(fl, host);
 165         /* Set up the argument struct */
 166         nlmclnt_setlockargs(call, fl);
 167
 168         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 169                 if (fl->fl_type != F_UNLCK) {
 170                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 171                         status = nlmclnt_lock(call, fl);
 172                 } else
 173                         status = nlmclnt_unlock(call, fl);
 174         } else if (IS_GETLK(cmd))
 175                 status = nlmclnt_test(call, fl);
 176         else
 177                 status = -EINVAL;
 178
 179         fl->fl_ops->fl_release_private(fl);
 180         fl->fl_ops = NULL;
 181
 182         dprintk("lockd: clnt proc returns %d\n", status);
 183         return status;
 184 }
 185 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 186
 187 /*
 188  * Allocate an NLM RPC call struct
 189  *
 190  * Note: the caller must hold a reference to host. In case of failure,
 191  * this reference will be released.
 192  */
 193 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 194 {
 195         struct nlm_rqst *call;
 196
 197         for(;;) {
 198                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 199                 if (call != NULL) {
 200                         atomic_set(&call->a_count, 1);
 201                         locks_init_lock(&call->a_args.lock.fl);
 202                         locks_init_lock(&call->a_res.lock.fl);
 203                         call->a_host = host;
 204                         return call;
 205                 }
 206                 if (signalled())
 207                         break;
 208                 printk("nlm_alloc_call: failed, waiting for memory\n");
 209                 schedule_timeout_interruptible(5*HZ);
 210         }
 211         nlm_release_host(host);
 212         return NULL;
 213 }
 214
 215 void nlm_release_call(struct nlm_rqst *call)
 216 {
 217         if (!atomic_dec_and_test(&call->a_count))
 218                 return;
 219         nlm_release_host(call->a_host);
 220         nlmclnt_release_lockargs(call);
 221         kfree(call);
 222 }
 223
 224 static void nlmclnt_rpc_release(void *data)
 225 {
 226         lock_kernel();
 227         nlm_release_call(data);
 228         unlock_kernel();
 229 }
 230
 231 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 232 {
 233         DEFINE_WAIT(wait);
 234         int status = -EINTR;
 235
 236         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 237         if (!signalled ()) {
 238                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 239                 try_to_freeze();
 240                 if (!signalled ())
 241                         status = 0;
 242         }
 243         finish_wait(queue, &wait);
 244         return status;
 245 }
 246
 247 /*
 248  * Generic NLM call
 249  */
 250 static int
 251 nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc)
 252 {
 253         struct nlm_host *host = req->a_host;
 254         struct rpc_clnt *clnt;
 255         struct nlm_args *argp = &req->a_args;
 256         struct nlm_res  *resp = &req->a_res;
 257         struct rpc_message msg = {
 258                 .rpc_argp       = argp,
 259                 .rpc_resp       = resp,
 260                 .rpc_cred       = cred,
 261         };
 262         int             status;
 263
 264         dprintk("lockd: call procedure %d on %s\n",
 265                         (int)proc, host->h_name);
 266
 267         do {
 268                 if (host->h_reclaiming && !argp->reclaim)
 269                         goto in_grace_period;
 270
 271                 /* If we have no RPC client yet, create one. */
 272                 if ((clnt = nlm_bind_host(host)) == NULL)
 273                         return -ENOLCK;
 274                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 275
 276                 /* Perform the RPC call. If an error occurs, try again */
 277                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 278                         dprintk("lockd: rpc_call returned error %d\n", -status);
 279                         switch (status) {
 280                         case -EPROTONOSUPPORT:
 281                                 status = -EINVAL;
 282                                 break;
 283                         case -ECONNREFUSED:
 284                         case -ETIMEDOUT:
 285                         case -ENOTCONN:
 286                                 nlm_rebind_host(host);
 287                                 status = -EAGAIN;
 288                                 break;
 289                         case -ERESTARTSYS:
 290                                 return signalled () ? -EINTR : status;
 291                         default:
 292                                 break;
 293                         }
 294                         break;
 295                 } else
 296                 if (resp->status == nlm_lck_denied_grace_period) {
 297                         dprintk("lockd: server in grace period\n");
 298                         if (argp->reclaim) {
 299                                 printk(KERN_WARNING
 300                                      "lockd: spurious grace period reject?!\n");
 301                                 return -ENOLCK;
 302                         }
 303                 } else {
 304                         if (!argp->reclaim) {
 305                                 /* We appear to be out of the grace period */
 306                                 wake_up_all(&host->h_gracewait);
 307                         }
 308                         dprintk("lockd: server returns status %d\n", resp->status);
 309                         return 0;       /* Okay, call complete */
 310                 }
 311
 312 in_grace_period:
 313                 /*
 314                  * The server has rebooted and appears to be in the grace
 315                  * period during which locks are only allowed to be
 316                  * reclaimed.
 317                  * We can only back off and try again later.
 318                  */
 319                 status = nlm_wait_on_grace(&host->h_gracewait);
 320         } while (status == 0);
 321
 322         return status;
 323 }
 324
 325 /*
 326  * Generic NLM call, async version.
 327  */
 328 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 329 {
 330         struct nlm_host *host = req->a_host;
 331         struct rpc_clnt *clnt;
 332         struct rpc_task_setup task_setup_data = {
 333                 .rpc_message = msg,
 334                 .callback_ops = tk_ops,
 335                 .callback_data = req,
 336                 .flags = RPC_TASK_ASYNC,
 337         };
 338
 339         dprintk("lockd: call procedure %d on %s (async)\n",
 340                         (int)proc, host->h_name);
 341
 342         /* If we have no RPC client yet, create one. */
 343         clnt = nlm_bind_host(host);
 344         if (clnt == NULL)
 345                 goto out_err;
 346         msg->rpc_proc = &clnt->cl_procinfo[proc];
 347         task_setup_data.rpc_client = clnt;
 348
 349         /* bootstrap and kick off the async RPC call */
 350         return rpc_run_task(&task_setup_data);
 351 out_err:
 352         tk_ops->rpc_release(req);
 353         return ERR_PTR(-ENOLCK);
 354 }
 355
 356 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 357 {
 358         struct rpc_task *task;
 359
 360         task = __nlm_async_call(req, proc, msg, tk_ops);
 361         if (IS_ERR(task))
 362                 return PTR_ERR(task);
 363         rpc_put_task(task);
 364         return 0;
 365 }
 366
 367 /*
 368  * NLM asynchronous call.
 369  */
 370 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 371 {
 372         struct rpc_message msg = {
 373                 .rpc_argp       = &req->a_args,
 374                 .rpc_resp       = &req->a_res,
 375         };
 376         return nlm_do_async_call(req, proc, &msg, tk_ops);
 377 }
 378
 379 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 380 {
 381         struct rpc_message msg = {
 382                 .rpc_argp       = &req->a_res,
 383         };
 384         return nlm_do_async_call(req, proc, &msg, tk_ops);
 385 }
 386
 387 /*
 388  * NLM client asynchronous call.
 389  *
 390  * Note that although the calls are asynchronous, and are therefore
 391  *      guaranteed to complete, we still always attempt to wait for
 392  *      completion in order to be able to correctly track the lock
 393  *      state.
 394  */
 395 static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 396 {
 397         struct rpc_message msg = {
 398                 .rpc_argp       = &req->a_args,
 399                 .rpc_resp       = &req->a_res,
 400                 .rpc_cred       = cred,
 401         };
 402         struct rpc_task *task;
 403         int err;
 404
 405         task = __nlm_async_call(req, proc, &msg, tk_ops);
 406         if (IS_ERR(task))
 407                 return PTR_ERR(task);
 408         err = rpc_wait_for_completion_task(task);
 409         rpc_put_task(task);
 410         return err;
 411 }
 412
 413 /*
 414  * TEST for the presence of a conflicting lock
 415  */
 416 static int
 417 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 418 {
 419         int     status;
 420
 421         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 422         if (status < 0)
 423                 goto out;
 424
 425         switch (req->a_res.status) {
 426                 case nlm_granted:
 427                         fl->fl_type = F_UNLCK;
 428                         break;
 429                 case nlm_lck_denied:
 430                         /*
 431                          * Report the conflicting lock back to the application.
 432                          */
 433                         fl->fl_start = req->a_res.lock.fl.fl_start;
 434                         fl->fl_end = req->a_res.lock.fl.fl_end;
 435                         fl->fl_type = req->a_res.lock.fl.fl_type;
 436                         fl->fl_pid = 0;
 437                         break;
 438                 default:
 439                         status = nlm_stat_to_errno(req->a_res.status);
 440         }
 441 out:
 442         nlm_release_call(req);
 443         return status;
 444 }
 445
 446 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 447 {
 448         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 449         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
 450         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 451 }
 452
 453 static void nlmclnt_locks_release_private(struct file_lock *fl)
 454 {
 455         list_del(&fl->fl_u.nfs_fl.list);
 456         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 457 }
 458
 459 static struct file_lock_operations nlmclnt_lock_ops = {
 460         .fl_copy_lock = nlmclnt_locks_copy_lock,
 461         .fl_release_private = nlmclnt_locks_release_private,
 462 };
 463
 464 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 465 {
 466         BUG_ON(fl->fl_ops != NULL);
 467         fl->fl_u.nfs_fl.state = 0;
 468         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 469         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 470         fl->fl_ops = &nlmclnt_lock_ops;
 471 }
 472
 473 static int do_vfs_lock(struct file_lock *fl)
 474 {
 475         int res = 0;
 476         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
 477                 case FL_POSIX:
 478                         res = posix_lock_file_wait(fl->fl_file, fl);
 479                         break;
 480                 case FL_FLOCK:
 481                         res = flock_lock_file_wait(fl->fl_file, fl);
 482                         break;
 483                 default:
 484                         BUG();
 485         }
 486         return res;
 487 }
 488
 489 /*
 490  * LOCK: Try to create a lock
 491  *
 492  *                      Programmer Harassment Alert
 493  *
 494  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 495  * will faithfully return LCK_BLOCKED but never cares to notify us when
 496  * the lock could be granted. This way, our local process could hang
 497  * around forever waiting for the callback.
 498  *
 499  *  Solution A: Implement busy-waiting
 500  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 501  *
 502  * For now I am implementing solution A, because I hate the idea of
 503  * re-implementing lockd for a third time in two months. The async
 504  * calls shouldn't be too hard to do, however.
 505  *
 506  * This is one of the lovely things about standards in the NFS area:
 507  * they're so soft and squishy you can't really blame HP for doing this.
 508  */
 509 static int
 510 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 511 {
 512         struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
 513         struct nlm_host *host = req->a_host;
 514         struct nlm_res  *resp = &req->a_res;
 515         struct nlm_wait *block = NULL;
 516         unsigned char fl_flags = fl->fl_flags;
 517         unsigned char fl_type;
 518         int status = -ENOLCK;
 519
 520         if (nsm_monitor(host) < 0)
 521                 goto out;
 522
 523         fl->fl_flags |= FL_ACCESS;
 524         status = do_vfs_lock(fl);
 525         fl->fl_flags = fl_flags;
 526         if (status < 0)
 527                 goto out;
 528
 529         block = nlmclnt_prepare_block(host, fl);
 530 again:
 531         /*
 532          * Initialise resp->status to a valid non-zero value,
 533          * since 0 == nlm_lck_granted
 534          */
 535         resp->status = nlm_lck_blocked;
 536         for(;;) {
 537                 /* Reboot protection */
 538                 fl->fl_u.nfs_fl.state = host->h_state;
 539                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 540                 if (status < 0)
 541                         break;
 542                 /* Did a reclaimer thread notify us of a server reboot? */
 543                 if (resp->status ==  nlm_lck_denied_grace_period)
 544                         continue;
 545                 if (resp->status != nlm_lck_blocked)
 546                         break;
 547                 /* Wait on an NLM blocking lock */
 548                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 549                 if (status < 0)
 550                         break;
 551                 if (resp->status != nlm_lck_blocked)
 552                         break;
 553         }
 554
 555         /* if we were interrupted while blocking, then cancel the lock request
 556          * and exit
 557          */
 558         if (resp->status == nlm_lck_blocked) {
 559                 if (!req->a_args.block)
 560                         goto out_unlock;
 561                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 562                         goto out_unblock;
 563         }
 564
 565         if (resp->status == nlm_granted) {
 566                 down_read(&host->h_rwsem);
 567                 /* Check whether or not the server has rebooted */
 568                 if (fl->fl_u.nfs_fl.state != host->h_state) {
 569                         up_read(&host->h_rwsem);
 570                         goto again;
 571                 }
 572                 /* Ensure the resulting lock will get added to granted list */
 573                 fl->fl_flags |= FL_SLEEP;
 574                 if (do_vfs_lock(fl) < 0)
 575                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 576                 up_read(&host->h_rwsem);
 577                 fl->fl_flags = fl_flags;
 578                 status = 0;
 579         }
 580         if (status < 0)
 581                 goto out_unlock;
 582         /*
 583          * EAGAIN doesn't make sense for sleeping locks, and in some
 584          * cases NLM_LCK_DENIED is returned for a permanent error.  So
 585          * turn it into an ENOLCK.
 586          */
 587         if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
 588                 status = -ENOLCK;
 589         else
 590                 status = nlm_stat_to_errno(resp->status);
 591 out_unblock:
 592         nlmclnt_finish_block(block);
 593 out:
 594         nlm_release_call(req);
 595         return status;
 596 out_unlock:
 597         /* Fatal error: ensure that we remove the lock altogether */
 598         dprintk("lockd: lock attempt ended in fatal error.\n"
 599                 "       Attempting to unlock.\n");
 600         nlmclnt_finish_block(block);
 601         fl_type = fl->fl_type;
 602         fl->fl_type = F_UNLCK;
 603         down_read(&host->h_rwsem);
 604         do_vfs_lock(fl);
 605         up_read(&host->h_rwsem);
 606         fl->fl_type = fl_type;
 607         fl->fl_flags = fl_flags;
 608         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 609         return status;
 610 }
 611
 612 /*
 613  * RECLAIM: Try to reclaim a lock
 614  */
 615 int
 616 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
 617 {
 618         struct nlm_rqst reqst, *req;
 619         int             status;
 620
 621         req = &reqst;
 622         memset(req, 0, sizeof(*req));
 623         locks_init_lock(&req->a_args.lock.fl);
 624         locks_init_lock(&req->a_res.lock.fl);
 625         req->a_host  = host;
 626         req->a_flags = 0;
 627
 628         /* Set up the argument struct */
 629         nlmclnt_setlockargs(req, fl);
 630         req->a_args.reclaim = 1;
 631
 632         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 633         if (status >= 0 && req->a_res.status == nlm_granted)
 634                 return 0;
 635
 636         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 637                                 "(errno %d, status %d)\n", fl->fl_pid,
 638                                 status, ntohl(req->a_res.status));
 639
 640         /*
 641          * FIXME: This is a serious failure. We can
 642          *
 643          *  a.  Ignore the problem
 644          *  b.  Send the owning process some signal (Linux doesn't have
 645          *      SIGLOST, though...)
 646          *  c.  Retry the operation
 647          *
 648          * Until someone comes up with a simple implementation
 649          * for b or c, I'll choose option a.
 650          */
 651
 652         return -ENOLCK;
 653 }
 654
 655 /*
 656  * UNLOCK: remove an existing lock
 657  */
 658 static int
 659 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 660 {
 661         struct nlm_host *host = req->a_host;
 662         struct nlm_res  *resp = &req->a_res;
 663         int status;
 664         unsigned char fl_flags = fl->fl_flags;
 665
 666         /*
 667          * Note: the server is supposed to either grant us the unlock
 668          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 669          * case, we want to unlock.
 670          */
 671         fl->fl_flags |= FL_EXISTS;
 672         down_read(&host->h_rwsem);
 673         status = do_vfs_lock(fl);
 674         up_read(&host->h_rwsem);
 675         fl->fl_flags = fl_flags;
 676         if (status == -ENOENT) {
 677                 status = 0;
 678                 goto out;
 679         }
 680
 681         atomic_inc(&req->a_count);
 682         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 683                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 684         if (status < 0)
 685                 goto out;
 686
 687         if (resp->status == nlm_granted)
 688                 goto out;
 689
 690         if (resp->status != nlm_lck_denied_nolocks)
 691                 printk("lockd: unexpected unlock status: %d\n", resp->status);
 692         /* What to do now? I'm out of my depth... */
 693         status = -ENOLCK;
 694 out:
 695         nlm_release_call(req);
 696         return status;
 697 }
 698
 699 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 700 {
 701         struct nlm_rqst *req = data;
 702         u32 status = ntohl(req->a_res.status);
 703
 704         if (RPC_ASSASSINATED(task))
 705                 goto die;
 706
 707         if (task->tk_status < 0) {
 708                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 709                 goto retry_rebind;
 710         }
 711         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 712                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 713                 goto retry_unlock;
 714         }
 715         if (status != NLM_LCK_GRANTED)
 716                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 717 die:
 718         return;
 719  retry_rebind:
 720         lock_kernel();
 721         nlm_rebind_host(req->a_host);
 722         unlock_kernel();
 723  retry_unlock:
 724         rpc_restart_call(task);
 725 }
 726
 727 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 728         .rpc_call_done = nlmclnt_unlock_callback,
 729         .rpc_release = nlmclnt_rpc_release,
 730 };
 731
 732 /*
 733  * Cancel a blocked lock request.
 734  * We always use an async RPC call for this in order not to hang a
 735  * process that has been Ctrl-C'ed.
 736  */
 737 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 738 {
 739         struct nlm_rqst *req;
 740         int status;
 741
 742         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 743                 "       Attempting to cancel lock.\n");
 744
 745         req = nlm_alloc_call(nlm_get_host(host));
 746         if (!req)
 747                 return -ENOMEM;
 748         req->a_flags = RPC_TASK_ASYNC;
 749
 750         nlmclnt_setlockargs(req, fl);
 751         req->a_args.block = block;
 752
 753         atomic_inc(&req->a_count);
 754         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 755                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 756         if (status == 0 && req->a_res.status == nlm_lck_denied)
 757                 status = -ENOLCK;
 758         nlm_release_call(req);
 759         return status;
 760 }
 761
 762 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 763 {
 764         struct nlm_rqst *req = data;
 765         u32 status = ntohl(req->a_res.status);
 766
 767         if (RPC_ASSASSINATED(task))
 768                 goto die;
 769
 770         if (task->tk_status < 0) {
 771                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 772                                         task->tk_status);
 773                 goto retry_cancel;
 774         }
 775
 776         dprintk("lockd: cancel status %u (task %u)\n",
 777                         status, task->tk_pid);
 778
 779         switch (status) {
 780         case NLM_LCK_GRANTED:
 781         case NLM_LCK_DENIED_GRACE_PERIOD:
 782         case NLM_LCK_DENIED:
 783                 /* Everything's good */
 784                 break;
 785         case NLM_LCK_DENIED_NOLOCKS:
 786                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 787                 goto retry_cancel;
 788         default:
 789                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 790                         status);
 791         }
 792
 793 die:
 794         return;
 795
 796 retry_cancel:
 797         /* Don't ever retry more than 3 times */
 798         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 799                 goto die;
 800         lock_kernel();
 801         nlm_rebind_host(req->a_host);
 802         unlock_kernel();
 803         rpc_restart_call(task);
 804         rpc_delay(task, 30 * HZ);
 805 }
 806
 807 static const struct rpc_call_ops nlmclnt_cancel_ops = {
 808         .rpc_call_done = nlmclnt_cancel_callback,
 809         .rpc_release = nlmclnt_rpc_release,
 810 };
 811
 812 /*
 813  * Convert an NLM status code to a generic kernel errno
 814  */
 815 static int
 816 nlm_stat_to_errno(__be32 status)
 817 {
 818         switch(ntohl(status)) {
 819         case NLM_LCK_GRANTED:
 820                 return 0;
 821         case NLM_LCK_DENIED:
 822                 return -EAGAIN;
 823         case NLM_LCK_DENIED_NOLOCKS:
 824         case NLM_LCK_DENIED_GRACE_PERIOD:
 825                 return -ENOLCK;
 826         case NLM_LCK_BLOCKED:
 827                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 828                 return -ENOLCK;
 829 #ifdef CONFIG_LOCKD_V4
 830         case NLM_DEADLCK:
 831                 return -EDEADLK;
 832         case NLM_ROFS:
 833                 return -EROFS;
 834         case NLM_STALE_FH:
 835                 return -ESTALE;
 836         case NLM_FBIG:
 837                 return -EOVERFLOW;
 838         case NLM_FAILED:
 839                 return -ENOLCK;
 840 #endif
 841         }
 842         printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
 843         return -ENOLCK;
 844 }