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/smp_lock.h>
  11 #include <linux/slab.h>
  12 #include <linux/types.h>
  13 #include <linux/errno.h>
  14 #include <linux/fs.h>
  15 #include <linux/nfs_fs.h>
  16 #include <linux/utsname.h>
  17 #include <linux/freezer.h>
  18 #include <linux/sunrpc/clnt.h>
  19 #include <linux/sunrpc/svc.h>
  20 #include <linux/lockd/lockd.h>
  21
  22 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  23 #define NLMCLNT_GRACE_WAIT      (5*HZ)
  24 #define NLMCLNT_POLL_TIMEOUT    (30*HZ)
  25 #define NLMCLNT_MAX_RETRIES     3
  26
  27 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
  28 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
  29 static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
  30 static int      nlm_stat_to_errno(__be32 stat);
  31 static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
  32 static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
  33
  34 static const struct rpc_call_ops nlmclnt_unlock_ops;
  35 static const struct rpc_call_ops nlmclnt_cancel_ops;
  36
  37 /*
  38  * Cookie counter for NLM requests
  39  */
  40 static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
  41
  42 void nlmclnt_next_cookie(struct nlm_cookie *c)
  43 {
  44         u32     cookie = atomic_inc_return(&nlm_cookie);
  45
  46         memcpy(c->data, &cookie, 4);
  47         c->len=4;
  48 }
  49
  50 static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
  51 {
  52         atomic_inc(&lockowner->count);
  53         return lockowner;
  54 }
  55
  56 static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
  57 {
  58         if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
  59                 return;
  60         list_del(&lockowner->list);
  61         spin_unlock(&lockowner->host->h_lock);
  62         nlm_release_host(lockowner->host);
  63         kfree(lockowner);
  64 }
  65
  66 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
  67 {
  68         struct nlm_lockowner *lockowner;
  69         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  70                 if (lockowner->pid == pid)
  71                         return -EBUSY;
  72         }
  73         return 0;
  74 }
  75
  76 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
  77 {
  78         uint32_t res;
  79         do {
  80                 res = host->h_pidcount++;
  81         } while (nlm_pidbusy(host, res) < 0);
  82         return res;
  83 }
  84
  85 static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  86 {
  87         struct nlm_lockowner *lockowner;
  88         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  89                 if (lockowner->owner != owner)
  90                         continue;
  91                 return nlm_get_lockowner(lockowner);
  92         }
  93         return NULL;
  94 }
  95
  96 static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  97 {
  98         struct nlm_lockowner *res, *new = NULL;
  99
 100         spin_lock(&host->h_lock);
 101         res = __nlm_find_lockowner(host, owner);
 102         if (res == NULL) {
 103                 spin_unlock(&host->h_lock);
 104                 new = kmalloc(sizeof(*new), GFP_KERNEL);
 105                 spin_lock(&host->h_lock);
 106                 res = __nlm_find_lockowner(host, owner);
 107                 if (res == NULL && new != NULL) {
 108                         res = new;
 109                         atomic_set(&new->count, 1);
 110                         new->owner = owner;
 111                         new->pid = __nlm_alloc_pid(host);
 112                         new->host = nlm_get_host(host);
 113                         list_add(&new->list, &host->h_lockowners);
 114                         new = NULL;
 115                 }
 116         }
 117         spin_unlock(&host->h_lock);
 118         kfree(new);
 119         return res;
 120 }
 121
 122 /*
 123  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 124  */
 125 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 126 {
 127         struct nlm_args *argp = &req->a_args;
 128         struct nlm_lock *lock = &argp->lock;
 129
 130         nlmclnt_next_cookie(&argp->cookie);
 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         lock_kernel();
 170         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 171                 if (fl->fl_type != F_UNLCK) {
 172                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 173                         status = nlmclnt_lock(call, fl);
 174                 } else
 175                         status = nlmclnt_unlock(call, fl);
 176         } else if (IS_GETLK(cmd))
 177                 status = nlmclnt_test(call, fl);
 178         else
 179                 status = -EINVAL;
 180
 181         fl->fl_ops->fl_release_private(fl);
 182         fl->fl_ops = NULL;
 183         unlock_kernel();
 184
 185         dprintk("lockd: clnt proc returns %d\n", status);
 186         return status;
 187 }
 188 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 189
 190 /*
 191  * Allocate an NLM RPC call struct
 192  *
 193  * Note: the caller must hold a reference to host. In case of failure,
 194  * this reference will be released.
 195  */
 196 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 197 {
 198         struct nlm_rqst *call;
 199
 200         for(;;) {
 201                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 202                 if (call != NULL) {
 203                         atomic_set(&call->a_count, 1);
 204                         locks_init_lock(&call->a_args.lock.fl);
 205                         locks_init_lock(&call->a_res.lock.fl);
 206                         call->a_host = host;
 207                         return call;
 208                 }
 209                 if (signalled())
 210                         break;
 211                 printk("nlm_alloc_call: failed, waiting for memory\n");
 212                 schedule_timeout_interruptible(5*HZ);
 213         }
 214         nlm_release_host(host);
 215         return NULL;
 216 }
 217
 218 void nlm_release_call(struct nlm_rqst *call)
 219 {
 220         if (!atomic_dec_and_test(&call->a_count))
 221                 return;
 222         nlm_release_host(call->a_host);
 223         nlmclnt_release_lockargs(call);
 224         kfree(call);
 225 }
 226
 227 static void nlmclnt_rpc_release(void *data)
 228 {
 229         lock_kernel();
 230         nlm_release_call(data);
 231         unlock_kernel();
 232 }
 233
 234 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 235 {
 236         DEFINE_WAIT(wait);
 237         int status = -EINTR;
 238
 239         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 240         if (!signalled ()) {
 241                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 242                 try_to_freeze();
 243                 if (!signalled ())
 244                         status = 0;
 245         }
 246         finish_wait(queue, &wait);
 247         return status;
 248 }
 249
 250 /*
 251  * Generic NLM call
 252  */
 253 static int
 254 nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc)
 255 {
 256         struct nlm_host *host = req->a_host;
 257         struct rpc_clnt *clnt;
 258         struct nlm_args *argp = &req->a_args;
 259         struct nlm_res  *resp = &req->a_res;
 260         struct rpc_message msg = {
 261                 .rpc_argp       = argp,
 262                 .rpc_resp       = resp,
 263                 .rpc_cred       = cred,
 264         };
 265         int             status;
 266
 267         dprintk("lockd: call procedure %d on %s\n",
 268                         (int)proc, host->h_name);
 269
 270         do {
 271                 if (host->h_reclaiming && !argp->reclaim)
 272                         goto in_grace_period;
 273
 274                 /* If we have no RPC client yet, create one. */
 275                 if ((clnt = nlm_bind_host(host)) == NULL)
 276                         return -ENOLCK;
 277                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 278
 279                 /* Perform the RPC call. If an error occurs, try again */
 280                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 281                         dprintk("lockd: rpc_call returned error %d\n", -status);
 282                         switch (status) {
 283                         case -EPROTONOSUPPORT:
 284                                 status = -EINVAL;
 285                                 break;
 286                         case -ECONNREFUSED:
 287                         case -ETIMEDOUT:
 288                         case -ENOTCONN:
 289                                 nlm_rebind_host(host);
 290                                 status = -EAGAIN;
 291                                 break;
 292                         case -ERESTARTSYS:
 293                                 return signalled () ? -EINTR : status;
 294                         default:
 295                                 break;
 296                         }
 297                         break;
 298                 } else
 299                 if (resp->status == nlm_lck_denied_grace_period) {
 300                         dprintk("lockd: server in grace period\n");
 301                         if (argp->reclaim) {
 302                                 printk(KERN_WARNING
 303                                      "lockd: spurious grace period reject?!\n");
 304                                 return -ENOLCK;
 305                         }
 306                 } else {
 307                         if (!argp->reclaim) {
 308                                 /* We appear to be out of the grace period */
 309                                 wake_up_all(&host->h_gracewait);
 310                         }
 311                         dprintk("lockd: server returns status %d\n", resp->status);
 312                         return 0;       /* Okay, call complete */
 313                 }
 314
 315 in_grace_period:
 316                 /*
 317                  * The server has rebooted and appears to be in the grace
 318                  * period during which locks are only allowed to be
 319                  * reclaimed.
 320                  * We can only back off and try again later.
 321                  */
 322                 status = nlm_wait_on_grace(&host->h_gracewait);
 323         } while (status == 0);
 324
 325         return status;
 326 }
 327
 328 /*
 329  * Generic NLM call, async version.
 330  */
 331 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 332 {
 333         struct nlm_host *host = req->a_host;
 334         struct rpc_clnt *clnt;
 335         struct rpc_task_setup task_setup_data = {
 336                 .rpc_message = msg,
 337                 .callback_ops = tk_ops,
 338                 .callback_data = req,
 339                 .flags = RPC_TASK_ASYNC,
 340         };
 341
 342         dprintk("lockd: call procedure %d on %s (async)\n",
 343                         (int)proc, host->h_name);
 344
 345         /* If we have no RPC client yet, create one. */
 346         clnt = nlm_bind_host(host);
 347         if (clnt == NULL)
 348                 goto out_err;
 349         msg->rpc_proc = &clnt->cl_procinfo[proc];
 350         task_setup_data.rpc_client = clnt;
 351
 352         /* bootstrap and kick off the async RPC call */
 353         return rpc_run_task(&task_setup_data);
 354 out_err:
 355         tk_ops->rpc_release(req);
 356         return ERR_PTR(-ENOLCK);
 357 }
 358
 359 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 360 {
 361         struct rpc_task *task;
 362
 363         task = __nlm_async_call(req, proc, msg, tk_ops);
 364         if (IS_ERR(task))
 365                 return PTR_ERR(task);
 366         rpc_put_task(task);
 367         return 0;
 368 }
 369
 370 /*
 371  * NLM asynchronous call.
 372  */
 373 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 374 {
 375         struct rpc_message msg = {
 376                 .rpc_argp       = &req->a_args,
 377                 .rpc_resp       = &req->a_res,
 378         };
 379         return nlm_do_async_call(req, proc, &msg, tk_ops);
 380 }
 381
 382 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 383 {
 384         struct rpc_message msg = {
 385                 .rpc_argp       = &req->a_res,
 386         };
 387         return nlm_do_async_call(req, proc, &msg, tk_ops);
 388 }
 389
 390 /*
 391  * NLM client asynchronous call.
 392  *
 393  * Note that although the calls are asynchronous, and are therefore
 394  *      guaranteed to complete, we still always attempt to wait for
 395  *      completion in order to be able to correctly track the lock
 396  *      state.
 397  */
 398 static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 399 {
 400         struct rpc_message msg = {
 401                 .rpc_argp       = &req->a_args,
 402                 .rpc_resp       = &req->a_res,
 403                 .rpc_cred       = cred,
 404         };
 405         struct rpc_task *task;
 406         int err;
 407
 408         task = __nlm_async_call(req, proc, &msg, tk_ops);
 409         if (IS_ERR(task))
 410                 return PTR_ERR(task);
 411         err = rpc_wait_for_completion_task(task);
 412         rpc_put_task(task);
 413         return err;
 414 }
 415
 416 /*
 417  * TEST for the presence of a conflicting lock
 418  */
 419 static int
 420 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 421 {
 422         int     status;
 423
 424         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 425         if (status < 0)
 426                 goto out;
 427
 428         switch (req->a_res.status) {
 429                 case nlm_granted:
 430                         fl->fl_type = F_UNLCK;
 431                         break;
 432                 case nlm_lck_denied:
 433                         /*
 434                          * Report the conflicting lock back to the application.
 435                          */
 436                         fl->fl_start = req->a_res.lock.fl.fl_start;
 437                         fl->fl_end = req->a_res.lock.fl.fl_end;
 438                         fl->fl_type = req->a_res.lock.fl.fl_type;
 439                         fl->fl_pid = 0;
 440                         break;
 441                 default:
 442                         status = nlm_stat_to_errno(req->a_res.status);
 443         }
 444 out:
 445         nlm_release_call(req);
 446         return status;
 447 }
 448
 449 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 450 {
 451         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 452         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
 453         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 454 }
 455
 456 static void nlmclnt_locks_release_private(struct file_lock *fl)
 457 {
 458         list_del(&fl->fl_u.nfs_fl.list);
 459         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 460 }
 461
 462 static const struct file_lock_operations nlmclnt_lock_ops = {
 463         .fl_copy_lock = nlmclnt_locks_copy_lock,
 464         .fl_release_private = nlmclnt_locks_release_private,
 465 };
 466
 467 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 468 {
 469         BUG_ON(fl->fl_ops != NULL);
 470         fl->fl_u.nfs_fl.state = 0;
 471         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 472         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 473         fl->fl_ops = &nlmclnt_lock_ops;
 474 }
 475
 476 static int do_vfs_lock(struct file_lock *fl)
 477 {
 478         int res = 0;
 479         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
 480                 case FL_POSIX:
 481                         res = posix_lock_file_wait(fl->fl_file, fl);
 482                         break;
 483                 case FL_FLOCK:
 484                         res = flock_lock_file_wait(fl->fl_file, fl);
 485                         break;
 486                 default:
 487                         BUG();
 488         }
 489         return res;
 490 }
 491
 492 /*
 493  * LOCK: Try to create a lock
 494  *
 495  *                      Programmer Harassment Alert
 496  *
 497  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 498  * will faithfully return LCK_BLOCKED but never cares to notify us when
 499  * the lock could be granted. This way, our local process could hang
 500  * around forever waiting for the callback.
 501  *
 502  *  Solution A: Implement busy-waiting
 503  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 504  *
 505  * For now I am implementing solution A, because I hate the idea of
 506  * re-implementing lockd for a third time in two months. The async
 507  * calls shouldn't be too hard to do, however.
 508  *
 509  * This is one of the lovely things about standards in the NFS area:
 510  * they're so soft and squishy you can't really blame HP for doing this.
 511  */
 512 static int
 513 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 514 {
 515         struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
 516         struct nlm_host *host = req->a_host;
 517         struct nlm_res  *resp = &req->a_res;
 518         struct nlm_wait *block = NULL;
 519         unsigned char fl_flags = fl->fl_flags;
 520         unsigned char fl_type;
 521         int status = -ENOLCK;
 522
 523         if (nsm_monitor(host) < 0)
 524                 goto out;
 525         req->a_args.state = nsm_local_state;
 526
 527         fl->fl_flags |= FL_ACCESS;
 528         status = do_vfs_lock(fl);
 529         fl->fl_flags = fl_flags;
 530         if (status < 0)
 531                 goto out;
 532
 533         block = nlmclnt_prepare_block(host, fl);
 534 again:
 535         /*
 536          * Initialise resp->status to a valid non-zero value,
 537          * since 0 == nlm_lck_granted
 538          */
 539         resp->status = nlm_lck_blocked;
 540         for(;;) {
 541                 /* Reboot protection */
 542                 fl->fl_u.nfs_fl.state = host->h_state;
 543                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 544                 if (status < 0)
 545                         break;
 546                 /* Did a reclaimer thread notify us of a server reboot? */
 547                 if (resp->status ==  nlm_lck_denied_grace_period)
 548                         continue;
 549                 if (resp->status != nlm_lck_blocked)
 550                         break;
 551                 /* Wait on an NLM blocking lock */
 552                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 553                 if (status < 0)
 554                         break;
 555                 if (resp->status != nlm_lck_blocked)
 556                         break;
 557         }
 558
 559         /* if we were interrupted while blocking, then cancel the lock request
 560          * and exit
 561          */
 562         if (resp->status == nlm_lck_blocked) {
 563                 if (!req->a_args.block)
 564                         goto out_unlock;
 565                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 566                         goto out_unblock;
 567         }
 568
 569         if (resp->status == nlm_granted) {
 570                 down_read(&host->h_rwsem);
 571                 /* Check whether or not the server has rebooted */
 572                 if (fl->fl_u.nfs_fl.state != host->h_state) {
 573                         up_read(&host->h_rwsem);
 574                         goto again;
 575                 }
 576                 /* Ensure the resulting lock will get added to granted list */
 577                 fl->fl_flags |= FL_SLEEP;
 578                 if (do_vfs_lock(fl) < 0)
 579                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 580                 up_read(&host->h_rwsem);
 581                 fl->fl_flags = fl_flags;
 582                 status = 0;
 583         }
 584         if (status < 0)
 585                 goto out_unlock;
 586         /*
 587          * EAGAIN doesn't make sense for sleeping locks, and in some
 588          * cases NLM_LCK_DENIED is returned for a permanent error.  So
 589          * turn it into an ENOLCK.
 590          */
 591         if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
 592                 status = -ENOLCK;
 593         else
 594                 status = nlm_stat_to_errno(resp->status);
 595 out_unblock:
 596         nlmclnt_finish_block(block);
 597 out:
 598         nlm_release_call(req);
 599         return status;
 600 out_unlock:
 601         /* Fatal error: ensure that we remove the lock altogether */
 602         dprintk("lockd: lock attempt ended in fatal error.\n"
 603                 "       Attempting to unlock.\n");
 604         nlmclnt_finish_block(block);
 605         fl_type = fl->fl_type;
 606         fl->fl_type = F_UNLCK;
 607         down_read(&host->h_rwsem);
 608         do_vfs_lock(fl);
 609         up_read(&host->h_rwsem);
 610         fl->fl_type = fl_type;
 611         fl->fl_flags = fl_flags;
 612         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 613         return status;
 614 }
 615
 616 /*
 617  * RECLAIM: Try to reclaim a lock
 618  */
 619 int
 620 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
 621 {
 622         struct nlm_rqst reqst, *req;
 623         int             status;
 624
 625         req = &reqst;
 626         memset(req, 0, sizeof(*req));
 627         locks_init_lock(&req->a_args.lock.fl);
 628         locks_init_lock(&req->a_res.lock.fl);
 629         req->a_host  = host;
 630         req->a_flags = 0;
 631
 632         /* Set up the argument struct */
 633         nlmclnt_setlockargs(req, fl);
 634         req->a_args.reclaim = 1;
 635
 636         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 637         if (status >= 0 && req->a_res.status == nlm_granted)
 638                 return 0;
 639
 640         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 641                                 "(errno %d, status %d)\n", fl->fl_pid,
 642                                 status, ntohl(req->a_res.status));
 643
 644         /*
 645          * FIXME: This is a serious failure. We can
 646          *
 647          *  a.  Ignore the problem
 648          *  b.  Send the owning process some signal (Linux doesn't have
 649          *      SIGLOST, though...)
 650          *  c.  Retry the operation
 651          *
 652          * Until someone comes up with a simple implementation
 653          * for b or c, I'll choose option a.
 654          */
 655
 656         return -ENOLCK;
 657 }
 658
 659 /*
 660  * UNLOCK: remove an existing lock
 661  */
 662 static int
 663 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 664 {
 665         struct nlm_host *host = req->a_host;
 666         struct nlm_res  *resp = &req->a_res;
 667         int status;
 668         unsigned char fl_flags = fl->fl_flags;
 669
 670         /*
 671          * Note: the server is supposed to either grant us the unlock
 672          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 673          * case, we want to unlock.
 674          */
 675         fl->fl_flags |= FL_EXISTS;
 676         down_read(&host->h_rwsem);
 677         status = do_vfs_lock(fl);
 678         up_read(&host->h_rwsem);
 679         fl->fl_flags = fl_flags;
 680         if (status == -ENOENT) {
 681                 status = 0;
 682                 goto out;
 683         }
 684
 685         atomic_inc(&req->a_count);
 686         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 687                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 688         if (status < 0)
 689                 goto out;
 690
 691         if (resp->status == nlm_granted)
 692                 goto out;
 693
 694         if (resp->status != nlm_lck_denied_nolocks)
 695                 printk("lockd: unexpected unlock status: %d\n", resp->status);
 696         /* What to do now? I'm out of my depth... */
 697         status = -ENOLCK;
 698 out:
 699         nlm_release_call(req);
 700         return status;
 701 }
 702
 703 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 704 {
 705         struct nlm_rqst *req = data;
 706         u32 status = ntohl(req->a_res.status);
 707
 708         if (RPC_ASSASSINATED(task))
 709                 goto die;
 710
 711         if (task->tk_status < 0) {
 712                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 713                 goto retry_rebind;
 714         }
 715         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 716                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 717                 goto retry_unlock;
 718         }
 719         if (status != NLM_LCK_GRANTED)
 720                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 721 die:
 722         return;
 723  retry_rebind:
 724         lock_kernel();
 725         nlm_rebind_host(req->a_host);
 726         unlock_kernel();
 727  retry_unlock:
 728         rpc_restart_call(task);
 729 }
 730
 731 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 732         .rpc_call_done = nlmclnt_unlock_callback,
 733         .rpc_release = nlmclnt_rpc_release,
 734 };
 735
 736 /*
 737  * Cancel a blocked lock request.
 738  * We always use an async RPC call for this in order not to hang a
 739  * process that has been Ctrl-C'ed.
 740  */
 741 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 742 {
 743         struct nlm_rqst *req;
 744         int status;
 745
 746         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 747                 "       Attempting to cancel lock.\n");
 748
 749         req = nlm_alloc_call(nlm_get_host(host));
 750         if (!req)
 751                 return -ENOMEM;
 752         req->a_flags = RPC_TASK_ASYNC;
 753
 754         nlmclnt_setlockargs(req, fl);
 755         req->a_args.block = block;
 756
 757         atomic_inc(&req->a_count);
 758         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 759                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 760         if (status == 0 && req->a_res.status == nlm_lck_denied)
 761                 status = -ENOLCK;
 762         nlm_release_call(req);
 763         return status;
 764 }
 765
 766 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 767 {
 768         struct nlm_rqst *req = data;
 769         u32 status = ntohl(req->a_res.status);
 770
 771         if (RPC_ASSASSINATED(task))
 772                 goto die;
 773
 774         if (task->tk_status < 0) {
 775                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 776                                         task->tk_status);
 777                 goto retry_cancel;
 778         }
 779
 780         dprintk("lockd: cancel status %u (task %u)\n",
 781                         status, task->tk_pid);
 782
 783         switch (status) {
 784         case NLM_LCK_GRANTED:
 785         case NLM_LCK_DENIED_GRACE_PERIOD:
 786         case NLM_LCK_DENIED:
 787                 /* Everything's good */
 788                 break;
 789         case NLM_LCK_DENIED_NOLOCKS:
 790                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 791                 goto retry_cancel;
 792         default:
 793                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 794                         status);
 795         }
 796
 797 die:
 798         return;
 799
 800 retry_cancel:
 801         /* Don't ever retry more than 3 times */
 802         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 803                 goto die;
 804         lock_kernel();
 805         nlm_rebind_host(req->a_host);
 806         unlock_kernel();
 807         rpc_restart_call(task);
 808         rpc_delay(task, 30 * HZ);
 809 }
 810
 811 static const struct rpc_call_ops nlmclnt_cancel_ops = {
 812         .rpc_call_done = nlmclnt_cancel_callback,
 813         .rpc_release = nlmclnt_rpc_release,
 814 };
 815
 816 /*
 817  * Convert an NLM status code to a generic kernel errno
 818  */
 819 static int
 820 nlm_stat_to_errno(__be32 status)
 821 {
 822         switch(ntohl(status)) {
 823         case NLM_LCK_GRANTED:
 824                 return 0;
 825         case NLM_LCK_DENIED:
 826                 return -EAGAIN;
 827         case NLM_LCK_DENIED_NOLOCKS:
 828         case NLM_LCK_DENIED_GRACE_PERIOD:
 829                 return -ENOLCK;
 830         case NLM_LCK_BLOCKED:
 831                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 832                 return -ENOLCK;
 833 #ifdef CONFIG_LOCKD_V4
 834         case NLM_DEADLCK:
 835                 return -EDEADLK;
 836         case NLM_ROFS:
 837                 return -EROFS;
 838         case NLM_STALE_FH:
 839                 return -ESTALE;
 840         case NLM_FBIG:
 841                 return -EOVERFLOW;
 842         case NLM_FAILED:
 843                 return -ENOLCK;
 844 #endif
 845         }
 846         printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
 847         return -ENOLCK;
 848 }