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(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         fl->fl_ops->fl_release_private(fl);
 179         fl->fl_ops = NULL;
 180
 181         dprintk("lockd: clnt proc returns %d\n", status);
 182         return status;
 183 }
 184 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 185
 186 /*
 187  * Allocate an NLM RPC call struct
 188  *
 189  * Note: the caller must hold a reference to host. In case of failure,
 190  * this reference will be released.
 191  */
 192 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 193 {
 194         struct nlm_rqst *call;
 195
 196         for(;;) {
 197                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 198                 if (call != NULL) {
 199                         atomic_set(&call->a_count, 1);
 200                         locks_init_lock(&call->a_args.lock.fl);
 201                         locks_init_lock(&call->a_res.lock.fl);
 202                         call->a_host = host;
 203                         return call;
 204                 }
 205                 if (signalled())
 206                         break;
 207                 printk("nlm_alloc_call: failed, waiting for memory\n");
 208                 schedule_timeout_interruptible(5*HZ);
 209         }
 210         nlmclnt_release_host(host);
 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", resp->status);
 306                         return 0;       /* Okay, call complete */
 307                 }
 308
 309 in_grace_period:
 310                 /*
 311                  * The server has rebooted and appears to be in the grace
 312                  * period during which locks are only allowed to be
 313                  * reclaimed.
 314                  * We can only back off and try again later.
 315                  */
 316                 status = nlm_wait_on_grace(&host->h_gracewait);
 317         } while (status == 0);
 318
 319         return status;
 320 }
 321
 322 /*
 323  * Generic NLM call, async version.
 324  */
 325 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 326 {
 327         struct nlm_host *host = req->a_host;
 328         struct rpc_clnt *clnt;
 329         struct rpc_task_setup task_setup_data = {
 330                 .rpc_message = msg,
 331                 .callback_ops = tk_ops,
 332                 .callback_data = req,
 333                 .flags = RPC_TASK_ASYNC,
 334         };
 335
 336         dprintk("lockd: call procedure %d on %s (async)\n",
 337                         (int)proc, host->h_name);
 338
 339         /* If we have no RPC client yet, create one. */
 340         clnt = nlm_bind_host(host);
 341         if (clnt == NULL)
 342                 goto out_err;
 343         msg->rpc_proc = &clnt->cl_procinfo[proc];
 344         task_setup_data.rpc_client = clnt;
 345
 346         /* bootstrap and kick off the async RPC call */
 347         return rpc_run_task(&task_setup_data);
 348 out_err:
 349         tk_ops->rpc_release(req);
 350         return ERR_PTR(-ENOLCK);
 351 }
 352
 353 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 354 {
 355         struct rpc_task *task;
 356
 357         task = __nlm_async_call(req, proc, msg, tk_ops);
 358         if (IS_ERR(task))
 359                 return PTR_ERR(task);
 360         rpc_put_task(task);
 361         return 0;
 362 }
 363
 364 /*
 365  * NLM asynchronous call.
 366  */
 367 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 368 {
 369         struct rpc_message msg = {
 370                 .rpc_argp       = &req->a_args,
 371                 .rpc_resp       = &req->a_res,
 372         };
 373         return nlm_do_async_call(req, proc, &msg, tk_ops);
 374 }
 375
 376 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 377 {
 378         struct rpc_message msg = {
 379                 .rpc_argp       = &req->a_res,
 380         };
 381         return nlm_do_async_call(req, proc, &msg, tk_ops);
 382 }
 383
 384 /*
 385  * NLM client asynchronous call.
 386  *
 387  * Note that although the calls are asynchronous, and are therefore
 388  *      guaranteed to complete, we still always attempt to wait for
 389  *      completion in order to be able to correctly track the lock
 390  *      state.
 391  */
 392 static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 393 {
 394         struct rpc_message msg = {
 395                 .rpc_argp       = &req->a_args,
 396                 .rpc_resp       = &req->a_res,
 397                 .rpc_cred       = cred,
 398         };
 399         struct rpc_task *task;
 400         int err;
 401
 402         task = __nlm_async_call(req, proc, &msg, tk_ops);
 403         if (IS_ERR(task))
 404                 return PTR_ERR(task);
 405         err = rpc_wait_for_completion_task(task);
 406         rpc_put_task(task);
 407         return err;
 408 }
 409
 410 /*
 411  * TEST for the presence of a conflicting lock
 412  */
 413 static int
 414 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 415 {
 416         int     status;
 417
 418         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 419         if (status < 0)
 420                 goto out;
 421
 422         switch (req->a_res.status) {
 423                 case nlm_granted:
 424                         fl->fl_type = F_UNLCK;
 425                         break;
 426                 case nlm_lck_denied:
 427                         /*
 428                          * Report the conflicting lock back to the application.
 429                          */
 430                         fl->fl_start = req->a_res.lock.fl.fl_start;
 431                         fl->fl_end = req->a_res.lock.fl.fl_end;
 432                         fl->fl_type = req->a_res.lock.fl.fl_type;
 433                         fl->fl_pid = 0;
 434                         break;
 435                 default:
 436                         status = nlm_stat_to_errno(req->a_res.status);
 437         }
 438 out:
 439         nlmclnt_release_call(req);
 440         return status;
 441 }
 442
 443 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 444 {
 445         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 446         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 447         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
 448         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 449         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 450 }
 451
 452 static void nlmclnt_locks_release_private(struct file_lock *fl)
 453 {
 454         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 455         list_del(&fl->fl_u.nfs_fl.list);
 456         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 457         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 458 }
 459
 460 static const struct file_lock_operations nlmclnt_lock_ops = {
 461         .fl_copy_lock = nlmclnt_locks_copy_lock,
 462         .fl_release_private = nlmclnt_locks_release_private,
 463 };
 464
 465 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 466 {
 467         BUG_ON(fl->fl_ops != NULL);
 468         fl->fl_u.nfs_fl.state = 0;
 469         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 470         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 471         fl->fl_ops = &nlmclnt_lock_ops;
 472 }
 473
 474 static int do_vfs_lock(struct file_lock *fl)
 475 {
 476         int res = 0;
 477         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
 478                 case FL_POSIX:
 479                         res = posix_lock_file_wait(fl->fl_file, fl);
 480                         break;
 481                 case FL_FLOCK:
 482                         res = flock_lock_file_wait(fl->fl_file, fl);
 483                         break;
 484                 default:
 485                         BUG();
 486         }
 487         return res;
 488 }
 489
 490 /*
 491  * LOCK: Try to create a lock
 492  *
 493  *                      Programmer Harassment Alert
 494  *
 495  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 496  * will faithfully return LCK_BLOCKED but never cares to notify us when
 497  * the lock could be granted. This way, our local process could hang
 498  * around forever waiting for the callback.
 499  *
 500  *  Solution A: Implement busy-waiting
 501  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 502  *
 503  * For now I am implementing solution A, because I hate the idea of
 504  * re-implementing lockd for a third time in two months. The async
 505  * calls shouldn't be too hard to do, however.
 506  *
 507  * This is one of the lovely things about standards in the NFS area:
 508  * they're so soft and squishy you can't really blame HP for doing this.
 509  */
 510 static int
 511 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 512 {
 513         struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
 514         struct nlm_host *host = req->a_host;
 515         struct nlm_res  *resp = &req->a_res;
 516         struct nlm_wait *block = NULL;
 517         unsigned char fl_flags = fl->fl_flags;
 518         unsigned char fl_type;
 519         int status = -ENOLCK;
 520
 521         if (nsm_monitor(host) < 0)
 522                 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 {
 620         struct nlm_rqst reqst, *req;
 621         int             status;
 622
 623         req = &reqst;
 624         memset(req, 0, sizeof(*req));
 625         locks_init_lock(&req->a_args.lock.fl);
 626         locks_init_lock(&req->a_res.lock.fl);
 627         req->a_host  = host;
 628         req->a_flags = 0;
 629
 630         /* Set up the argument struct */
 631         nlmclnt_setlockargs(req, fl);
 632         req->a_args.reclaim = 1;
 633
 634         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 635         if (status >= 0 && req->a_res.status == nlm_granted)
 636                 return 0;
 637
 638         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 639                                 "(errno %d, status %d)\n", fl->fl_pid,
 640                                 status, ntohl(req->a_res.status));
 641
 642         /*
 643          * FIXME: This is a serious failure. We can
 644          *
 645          *  a.  Ignore the problem
 646          *  b.  Send the owning process some signal (Linux doesn't have
 647          *      SIGLOST, though...)
 648          *  c.  Retry the operation
 649          *
 650          * Until someone comes up with a simple implementation
 651          * for b or c, I'll choose option a.
 652          */
 653
 654         return -ENOLCK;
 655 }
 656
 657 /*
 658  * UNLOCK: remove an existing lock
 659  */
 660 static int
 661 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 662 {
 663         struct nlm_host *host = req->a_host;
 664         struct nlm_res  *resp = &req->a_res;
 665         int status;
 666         unsigned char fl_flags = fl->fl_flags;
 667
 668         /*
 669          * Note: the server is supposed to either grant us the unlock
 670          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 671          * case, we want to unlock.
 672          */
 673         fl->fl_flags |= FL_EXISTS;
 674         down_read(&host->h_rwsem);
 675         status = do_vfs_lock(fl);
 676         up_read(&host->h_rwsem);
 677         fl->fl_flags = fl_flags;
 678         if (status == -ENOENT) {
 679                 status = 0;
 680                 goto out;
 681         }
 682
 683         atomic_inc(&req->a_count);
 684         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 685                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 686         if (status < 0)
 687                 goto out;
 688
 689         if (resp->status == nlm_granted)
 690                 goto out;
 691
 692         if (resp->status != nlm_lck_denied_nolocks)
 693                 printk("lockd: unexpected unlock status: %d\n", resp->status);
 694         /* What to do now? I'm out of my depth... */
 695         status = -ENOLCK;
 696 out:
 697         nlmclnt_release_call(req);
 698         return status;
 699 }
 700
 701 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 702 {
 703         struct nlm_rqst *req = data;
 704         u32 status = ntohl(req->a_res.status);
 705
 706         if (RPC_ASSASSINATED(task))
 707                 goto die;
 708
 709         if (task->tk_status < 0) {
 710                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 711                 switch (task->tk_status) {
 712                 case -EACCES:
 713                 case -EIO:
 714                         goto die;
 715                 default:
 716                         goto retry_rebind;
 717                 }
 718         }
 719         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 720                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 721                 goto retry_unlock;
 722         }
 723         if (status != NLM_LCK_GRANTED)
 724                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 725 die:
 726         return;
 727  retry_rebind:
 728         nlm_rebind_host(req->a_host);
 729  retry_unlock:
 730         rpc_restart_call(task);
 731 }
 732
 733 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 734         .rpc_call_done = nlmclnt_unlock_callback,
 735         .rpc_release = nlmclnt_rpc_release,
 736 };
 737
 738 /*
 739  * Cancel a blocked lock request.
 740  * We always use an async RPC call for this in order not to hang a
 741  * process that has been Ctrl-C'ed.
 742  */
 743 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 744 {
 745         struct nlm_rqst *req;
 746         int status;
 747
 748         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 749                 "       Attempting to cancel lock.\n");
 750
 751         req = nlm_alloc_call(nlm_get_host(host));
 752         if (!req)
 753                 return -ENOMEM;
 754         req->a_flags = RPC_TASK_ASYNC;
 755
 756         nlmclnt_setlockargs(req, fl);
 757         req->a_args.block = block;
 758
 759         atomic_inc(&req->a_count);
 760         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 761                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 762         if (status == 0 && req->a_res.status == nlm_lck_denied)
 763                 status = -ENOLCK;
 764         nlmclnt_release_call(req);
 765         return status;
 766 }
 767
 768 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 769 {
 770         struct nlm_rqst *req = data;
 771         u32 status = ntohl(req->a_res.status);
 772
 773         if (RPC_ASSASSINATED(task))
 774                 goto die;
 775
 776         if (task->tk_status < 0) {
 777                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 778                                         task->tk_status);
 779                 goto retry_cancel;
 780         }
 781
 782         dprintk("lockd: cancel status %u (task %u)\n",
 783                         status, task->tk_pid);
 784
 785         switch (status) {
 786         case NLM_LCK_GRANTED:
 787         case NLM_LCK_DENIED_GRACE_PERIOD:
 788         case NLM_LCK_DENIED:
 789                 /* Everything's good */
 790                 break;
 791         case NLM_LCK_DENIED_NOLOCKS:
 792                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 793                 goto retry_cancel;
 794         default:
 795                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 796                         status);
 797         }
 798
 799 die:
 800         return;
 801
 802 retry_cancel:
 803         /* Don't ever retry more than 3 times */
 804         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 805                 goto die;
 806         nlm_rebind_host(req->a_host);
 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 }