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