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/slab.h>
  11 #include <linux/types.h>
  12 #include <linux/errno.h>
  13 #include <linux/fs.h>
  14 #include <linux/nfs_fs.h>
  15 #include <linux/utsname.h>
  16 #include <linux/freezer.h>
  17 #include <linux/sunrpc/clnt.h>
  18 #include <linux/sunrpc/svc.h>
  19 #include <linux/lockd/lockd.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         nlmclnt_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         memcpy(&lock->fh, NFS_FH(file_inode(fl->fl_file)), 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         WARN_ON_ONCE(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         call = nlm_alloc_call(host);
 160         if (call == NULL)
 161                 return -ENOMEM;
 162
 163         nlmclnt_locks_init_private(fl, host);
 164         if (!fl->fl_u.nfs_fl.owner) {
 165                 /* lockowner allocation has failed */
 166                 nlmclnt_release_call(call);
 167                 return -ENOMEM;
 168         }
 169         /* Set up the argument struct */
 170         nlmclnt_setlockargs(call, fl);
 171
 172         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 173                 if (fl->fl_type != F_UNLCK) {
 174                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 175                         status = nlmclnt_lock(call, fl);
 176                 } else
 177                         status = nlmclnt_unlock(call, fl);
 178         } else if (IS_GETLK(cmd))
 179                 status = nlmclnt_test(call, fl);
 180         else
 181                 status = -EINVAL;
 182         fl->fl_ops->fl_release_private(fl);
 183         fl->fl_ops = NULL;
 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 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 = nlm_get_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         return NULL;
 212 }
 213
 214 void nlmclnt_release_call(struct nlm_rqst *call)
 215 {
 216         if (!atomic_dec_and_test(&call->a_count))
 217                 return;
 218         nlmclnt_release_host(call->a_host);
 219         nlmclnt_release_lockargs(call);
 220         kfree(call);
 221 }
 222
 223 static void nlmclnt_rpc_release(void *data)
 224 {
 225         nlmclnt_release_call(data);
 226 }
 227
 228 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 229 {
 230         DEFINE_WAIT(wait);
 231         int status = -EINTR;
 232
 233         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 234         if (!signalled ()) {
 235                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 236                 try_to_freeze();
 237                 if (!signalled ())
 238                         status = 0;
 239         }
 240         finish_wait(queue, &wait);
 241         return status;
 242 }
 243
 244 /*
 245  * Generic NLM call
 246  */
 247 static int
 248 nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc)
 249 {
 250         struct nlm_host *host = req->a_host;
 251         struct rpc_clnt *clnt;
 252         struct nlm_args *argp = &req->a_args;
 253         struct nlm_res  *resp = &req->a_res;
 254         struct rpc_message msg = {
 255                 .rpc_argp       = argp,
 256                 .rpc_resp       = resp,
 257                 .rpc_cred       = cred,
 258         };
 259         int             status;
 260
 261         dprintk("lockd: call procedure %d on %s\n",
 262                         (int)proc, host->h_name);
 263
 264         do {
 265                 if (host->h_reclaiming && !argp->reclaim)
 266                         goto in_grace_period;
 267
 268                 /* If we have no RPC client yet, create one. */
 269                 if ((clnt = nlm_bind_host(host)) == NULL)
 270                         return -ENOLCK;
 271                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 272
 273                 /* Perform the RPC call. If an error occurs, try again */
 274                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 275                         dprintk("lockd: rpc_call returned error %d\n", -status);
 276                         switch (status) {
 277                         case -EPROTONOSUPPORT:
 278                                 status = -EINVAL;
 279                                 break;
 280                         case -ECONNREFUSED:
 281                         case -ETIMEDOUT:
 282                         case -ENOTCONN:
 283                                 nlm_rebind_host(host);
 284                                 status = -EAGAIN;
 285                                 break;
 286                         case -ERESTARTSYS:
 287                                 return signalled () ? -EINTR : status;
 288                         default:
 289                                 break;
 290                         }
 291                         break;
 292                 } else
 293                 if (resp->status == nlm_lck_denied_grace_period) {
 294                         dprintk("lockd: server in grace period\n");
 295                         if (argp->reclaim) {
 296                                 printk(KERN_WARNING
 297                                      "lockd: spurious grace period reject?!\n");
 298                                 return -ENOLCK;
 299                         }
 300                 } else {
 301                         if (!argp->reclaim) {
 302                                 /* We appear to be out of the grace period */
 303                                 wake_up_all(&host->h_gracewait);
 304                         }
 305                         dprintk("lockd: server returns status %d\n",
 306                                 ntohl(resp->status));
 307                         return 0;       /* Okay, call complete */
 308                 }
 309
 310 in_grace_period:
 311                 /*
 312                  * The server has rebooted and appears to be in the grace
 313                  * period during which locks are only allowed to be
 314                  * reclaimed.
 315                  * We can only back off and try again later.
 316                  */
 317                 status = nlm_wait_on_grace(&host->h_gracewait);
 318         } while (status == 0);
 319
 320         return status;
 321 }
 322
 323 /*
 324  * Generic NLM call, async version.
 325  */
 326 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 327 {
 328         struct nlm_host *host = req->a_host;
 329         struct rpc_clnt *clnt;
 330         struct rpc_task_setup task_setup_data = {
 331                 .rpc_message = msg,
 332                 .callback_ops = tk_ops,
 333                 .callback_data = req,
 334                 .flags = RPC_TASK_ASYNC,
 335         };
 336
 337         dprintk("lockd: call procedure %d on %s (async)\n",
 338                         (int)proc, host->h_name);
 339
 340         /* If we have no RPC client yet, create one. */
 341         clnt = nlm_bind_host(host);
 342         if (clnt == NULL)
 343                 goto out_err;
 344         msg->rpc_proc = &clnt->cl_procinfo[proc];
 345         task_setup_data.rpc_client = clnt;
 346
 347         /* bootstrap and kick off the async RPC call */
 348         return rpc_run_task(&task_setup_data);
 349 out_err:
 350         tk_ops->rpc_release(req);
 351         return ERR_PTR(-ENOLCK);
 352 }
 353
 354 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 355 {
 356         struct rpc_task *task;
 357
 358         task = __nlm_async_call(req, proc, msg, tk_ops);
 359         if (IS_ERR(task))
 360                 return PTR_ERR(task);
 361         rpc_put_task(task);
 362         return 0;
 363 }
 364
 365 /*
 366  * NLM asynchronous call.
 367  */
 368 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 369 {
 370         struct rpc_message msg = {
 371                 .rpc_argp       = &req->a_args,
 372                 .rpc_resp       = &req->a_res,
 373         };
 374         return nlm_do_async_call(req, proc, &msg, tk_ops);
 375 }
 376
 377 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 378 {
 379         struct rpc_message msg = {
 380                 .rpc_argp       = &req->a_res,
 381         };
 382         return nlm_do_async_call(req, proc, &msg, tk_ops);
 383 }
 384
 385 /*
 386  * NLM client asynchronous call.
 387  *
 388  * Note that although the calls are asynchronous, and are therefore
 389  *      guaranteed to complete, we still always attempt to wait for
 390  *      completion in order to be able to correctly track the lock
 391  *      state.
 392  */
 393 static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 394 {
 395         struct rpc_message msg = {
 396                 .rpc_argp       = &req->a_args,
 397                 .rpc_resp       = &req->a_res,
 398                 .rpc_cred       = cred,
 399         };
 400         struct rpc_task *task;
 401         int err;
 402
 403         task = __nlm_async_call(req, proc, &msg, tk_ops);
 404         if (IS_ERR(task))
 405                 return PTR_ERR(task);
 406         err = rpc_wait_for_completion_task(task);
 407         rpc_put_task(task);
 408         return err;
 409 }
 410
 411 /*
 412  * TEST for the presence of a conflicting lock
 413  */
 414 static int
 415 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 416 {
 417         int     status;
 418
 419         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 420         if (status < 0)
 421                 goto out;
 422
 423         switch (req->a_res.status) {
 424                 case nlm_granted:
 425                         fl->fl_type = F_UNLCK;
 426                         break;
 427                 case nlm_lck_denied:
 428                         /*
 429                          * Report the conflicting lock back to the application.
 430                          */
 431                         fl->fl_start = req->a_res.lock.fl.fl_start;
 432                         fl->fl_end = req->a_res.lock.fl.fl_end;
 433                         fl->fl_type = req->a_res.lock.fl.fl_type;
 434                         fl->fl_pid = 0;
 435                         break;
 436                 default:
 437                         status = nlm_stat_to_errno(req->a_res.status);
 438         }
 439 out:
 440         nlmclnt_release_call(req);
 441         return status;
 442 }
 443
 444 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 445 {
 446         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 447         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 448         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
 449         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 450         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 451 }
 452
 453 static void nlmclnt_locks_release_private(struct file_lock *fl)
 454 {
 455         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 456         list_del(&fl->fl_u.nfs_fl.list);
 457         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 458         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 459 }
 460
 461 static const struct file_lock_operations nlmclnt_lock_ops = {
 462         .fl_copy_lock = nlmclnt_locks_copy_lock,
 463         .fl_release_private = nlmclnt_locks_release_private,
 464 };
 465
 466 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 467 {
 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                 goto out;
 523         req->a_args.state = nsm_local_state;
 524
 525         fl->fl_flags |= FL_ACCESS;
 526         status = do_vfs_lock(fl);
 527         fl->fl_flags = fl_flags;
 528         if (status < 0)
 529                 goto out;
 530
 531         block = nlmclnt_prepare_block(host, fl);
 532 again:
 533         /*
 534          * Initialise resp->status to a valid non-zero value,
 535          * since 0 == nlm_lck_granted
 536          */
 537         resp->status = nlm_lck_blocked;
 538         for(;;) {
 539                 /* Reboot protection */
 540                 fl->fl_u.nfs_fl.state = host->h_state;
 541                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 542                 if (status < 0)
 543                         break;
 544                 /* Did a reclaimer thread notify us of a server reboot? */
 545                 if (resp->status ==  nlm_lck_denied_grace_period)
 546                         continue;
 547                 if (resp->status != nlm_lck_blocked)
 548                         break;
 549                 /* Wait on an NLM blocking lock */
 550                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 551                 if (status < 0)
 552                         break;
 553                 if (resp->status != nlm_lck_blocked)
 554                         break;
 555         }
 556
 557         /* if we were interrupted while blocking, then cancel the lock request
 558          * and exit
 559          */
 560         if (resp->status == nlm_lck_blocked) {
 561                 if (!req->a_args.block)
 562                         goto out_unlock;
 563                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 564                         goto out_unblock;
 565         }
 566
 567         if (resp->status == nlm_granted) {
 568                 down_read(&host->h_rwsem);
 569                 /* Check whether or not the server has rebooted */
 570                 if (fl->fl_u.nfs_fl.state != host->h_state) {
 571                         up_read(&host->h_rwsem);
 572                         goto again;
 573                 }
 574                 /* Ensure the resulting lock will get added to granted list */
 575                 fl->fl_flags |= FL_SLEEP;
 576                 if (do_vfs_lock(fl) < 0)
 577                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 578                 up_read(&host->h_rwsem);
 579                 fl->fl_flags = fl_flags;
 580                 status = 0;
 581         }
 582         if (status < 0)
 583                 goto out_unlock;
 584         /*
 585          * EAGAIN doesn't make sense for sleeping locks, and in some
 586          * cases NLM_LCK_DENIED is returned for a permanent error.  So
 587          * turn it into an ENOLCK.
 588          */
 589         if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
 590                 status = -ENOLCK;
 591         else
 592                 status = nlm_stat_to_errno(resp->status);
 593 out_unblock:
 594         nlmclnt_finish_block(block);
 595 out:
 596         nlmclnt_release_call(req);
 597         return status;
 598 out_unlock:
 599         /* Fatal error: ensure that we remove the lock altogether */
 600         dprintk("lockd: lock attempt ended in fatal error.\n"
 601                 "       Attempting to unlock.\n");
 602         nlmclnt_finish_block(block);
 603         fl_type = fl->fl_type;
 604         fl->fl_type = F_UNLCK;
 605         down_read(&host->h_rwsem);
 606         do_vfs_lock(fl);
 607         up_read(&host->h_rwsem);
 608         fl->fl_type = fl_type;
 609         fl->fl_flags = fl_flags;
 610         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 611         return status;
 612 }
 613
 614 /*
 615  * RECLAIM: Try to reclaim a lock
 616  */
 617 int
 618 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
 619                 struct nlm_rqst *req)
 620 {
 621         int             status;
 622
 623         memset(req, 0, sizeof(*req));
 624         locks_init_lock(&req->a_args.lock.fl);
 625         locks_init_lock(&req->a_res.lock.fl);
 626         req->a_host  = host;
 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",
 692                         ntohl(resp->status));
 693         /* What to do now? I'm out of my depth... */
 694         status = -ENOLCK;
 695 out:
 696         nlmclnt_release_call(req);
 697         return status;
 698 }
 699
 700 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 701 {
 702         struct nlm_rqst *req = data;
 703         u32 status = ntohl(req->a_res.status);
 704
 705         if (RPC_ASSASSINATED(task))
 706                 goto die;
 707
 708         if (task->tk_status < 0) {
 709                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 710                 switch (task->tk_status) {
 711                 case -EACCES:
 712                 case -EIO:
 713                         goto die;
 714                 default:
 715                         goto retry_rebind;
 716                 }
 717         }
 718         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 719                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 720                 goto retry_unlock;
 721         }
 722         if (status != NLM_LCK_GRANTED)
 723                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 724 die:
 725         return;
 726  retry_rebind:
 727         nlm_rebind_host(req->a_host);
 728  retry_unlock:
 729         rpc_restart_call(task);
 730 }
 731
 732 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 733         .rpc_call_done = nlmclnt_unlock_callback,
 734         .rpc_release = nlmclnt_rpc_release,
 735 };
 736
 737 /*
 738  * Cancel a blocked lock request.
 739  * We always use an async RPC call for this in order not to hang a
 740  * process that has been Ctrl-C'ed.
 741  */
 742 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 743 {
 744         struct nlm_rqst *req;
 745         int status;
 746
 747         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 748                 "       Attempting to cancel lock.\n");
 749
 750         req = nlm_alloc_call(host);
 751         if (!req)
 752                 return -ENOMEM;
 753         req->a_flags = RPC_TASK_ASYNC;
 754
 755         nlmclnt_setlockargs(req, fl);
 756         req->a_args.block = block;
 757
 758         atomic_inc(&req->a_count);
 759         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 760                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 761         if (status == 0 && req->a_res.status == nlm_lck_denied)
 762                 status = -ENOLCK;
 763         nlmclnt_release_call(req);
 764         return status;
 765 }
 766
 767 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 768 {
 769         struct nlm_rqst *req = data;
 770         u32 status = ntohl(req->a_res.status);
 771
 772         if (RPC_ASSASSINATED(task))
 773                 goto die;
 774
 775         if (task->tk_status < 0) {
 776                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 777                                         task->tk_status);
 778                 goto retry_cancel;
 779         }
 780
 781         dprintk("lockd: cancel status %u (task %u)\n",
 782                         status, task->tk_pid);
 783
 784         switch (status) {
 785         case NLM_LCK_GRANTED:
 786         case NLM_LCK_DENIED_GRACE_PERIOD:
 787         case NLM_LCK_DENIED:
 788                 /* Everything's good */
 789                 break;
 790         case NLM_LCK_DENIED_NOLOCKS:
 791                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 792                 goto retry_cancel;
 793         default:
 794                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 795                         status);
 796         }
 797
 798 die:
 799         return;
 800
 801 retry_cancel:
 802         /* Don't ever retry more than 3 times */
 803         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 804                 goto die;
 805         nlm_rebind_host(req->a_host);
 806         rpc_restart_call(task);
 807         rpc_delay(task, 30 * HZ);
 808 }
 809
 810 static const struct rpc_call_ops nlmclnt_cancel_ops = {
 811         .rpc_call_done = nlmclnt_cancel_callback,
 812         .rpc_release = nlmclnt_rpc_release,
 813 };
 814
 815 /*
 816  * Convert an NLM status code to a generic kernel errno
 817  */
 818 static int
 819 nlm_stat_to_errno(__be32 status)
 820 {
 821         switch(ntohl(status)) {
 822         case NLM_LCK_GRANTED:
 823                 return 0;
 824         case NLM_LCK_DENIED:
 825                 return -EAGAIN;
 826         case NLM_LCK_DENIED_NOLOCKS:
 827         case NLM_LCK_DENIED_GRACE_PERIOD:
 828                 return -ENOLCK;
 829         case NLM_LCK_BLOCKED:
 830                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 831                 return -ENOLCK;
 832 #ifdef CONFIG_LOCKD_V4
 833         case NLM_DEADLCK:
 834                 return -EDEADLK;
 835         case NLM_ROFS:
 836                 return -EROFS;
 837         case NLM_STALE_FH:
 838                 return -ESTALE;
 839         case NLM_FBIG:
 840                 return -EOVERFLOW;
 841         case NLM_FAILED:
 842                 return -ENOLCK;
 843 #endif
 844         }
 845         printk(KERN_NOTICE "lockd: unexpected server status %d\n",
 846                  ntohl(status));
 847         return -ENOLCK;
 848 }