fs/lockd/clntproc.c

   1 /*
   2  * linux/fs/lockd/clntproc.c
   3  *
   4  * RPC procedures for the client side NLM implementation
   5  *
   6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/types.h>
  11 #include <linux/errno.h>
  12 #include <linux/fs.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/utsname.h>
  15 #include <linux/freezer.h>
  16 #include <linux/sunrpc/clnt.h>
  17 #include <linux/sunrpc/svc.h>
  18 #include <linux/lockd/lockd.h>
  19 #include <linux/lockd/sm_inter.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         argp->state   = nsm_local_state;
 131         memcpy(&lock->fh, NFS_FH(fl->fl_file->f_path.dentry->d_inode), sizeof(struct nfs_fh));
 132         lock->caller  = utsname()->nodename;
 133         lock->oh.data = req->a_owner;
 134         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
 135                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
 136                                 utsname()->nodename);
 137         lock->svid = fl->fl_u.nfs_fl.owner->pid;
 138         lock->fl.fl_start = fl->fl_start;
 139         lock->fl.fl_end = fl->fl_end;
 140         lock->fl.fl_type = fl->fl_type;
 141 }
 142
 143 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
 144 {
 145         BUG_ON(req->a_args.lock.fl.fl_ops != NULL);
 146 }
 147
 148 /**
 149  * nlmclnt_proc - Perform a single client-side lock request
 150  * @host: address of a valid nlm_host context representing the NLM server
 151  * @cmd: fcntl-style file lock operation to perform
 152  * @fl: address of arguments for the lock operation
 153  *
 154  */
 155 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
 156 {
 157         struct nlm_rqst         *call;
 158         int                     status;
 159
 160         nlm_get_host(host);
 161         call = nlm_alloc_call(host);
 162         if (call == NULL)
 163                 return -ENOMEM;
 164
 165         nlmclnt_locks_init_private(fl, host);
 166         /* Set up the argument struct */
 167         nlmclnt_setlockargs(call, fl);
 168
 169         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
 183         dprintk("lockd: clnt proc returns %d\n", status);
 184         return status;
 185 }
 186 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 187
 188 /*
 189  * Allocate an NLM RPC call struct
 190  *
 191  * Note: the caller must hold a reference to host. In case of failure,
 192  * this reference will be released.
 193  */
 194 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 195 {
 196         struct nlm_rqst *call;
 197
 198         for(;;) {
 199                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 200                 if (call != NULL) {
 201                         atomic_set(&call->a_count, 1);
 202                         locks_init_lock(&call->a_args.lock.fl);
 203                         locks_init_lock(&call->a_res.lock.fl);
 204                         call->a_host = host;
 205                         return call;
 206                 }
 207                 if (signalled())
 208                         break;
 209                 printk("nlm_alloc_call: failed, waiting for memory\n");
 210                 schedule_timeout_interruptible(5*HZ);
 211         }
 212         nlm_release_host(host);
 213         return NULL;
 214 }
 215
 216 void nlm_release_call(struct nlm_rqst *call)
 217 {
 218         if (!atomic_dec_and_test(&call->a_count))
 219                 return;
 220         nlm_release_host(call->a_host);
 221         nlmclnt_release_lockargs(call);
 222         kfree(call);
 223 }
 224
 225 static void nlmclnt_rpc_release(void *data)
 226 {
 227         nlm_release_call(data);
 228 }
 229
 230 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 231 {
 232         DEFINE_WAIT(wait);
 233         int status = -EINTR;
 234
 235         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 236         if (!signalled ()) {
 237                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 238                 try_to_freeze();
 239                 if (!signalled ())
 240                         status = 0;
 241         }
 242         finish_wait(queue, &wait);
 243         return status;
 244 }
 245
 246 /*
 247  * Generic NLM call
 248  */
 249 static int
 250 nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc)
 251 {
 252         struct nlm_host *host = req->a_host;
 253         struct rpc_clnt *clnt;
 254         struct nlm_args *argp = &req->a_args;
 255         struct nlm_res  *resp = &req->a_res;
 256         struct rpc_message msg = {
 257                 .rpc_argp       = argp,
 258                 .rpc_resp       = resp,
 259                 .rpc_cred       = cred,
 260         };
 261         int             status;
 262
 263         dprintk("lockd: call procedure %d on %s\n",
 264                         (int)proc, host->h_name);
 265
 266         do {
 267                 if (host->h_reclaiming && !argp->reclaim)
 268                         goto in_grace_period;
 269
 270                 /* If we have no RPC client yet, create one. */
 271                 if ((clnt = nlm_bind_host(host)) == NULL)
 272                         return -ENOLCK;
 273                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 274
 275                 /* Perform the RPC call. If an error occurs, try again */
 276                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 277                         dprintk("lockd: rpc_call returned error %d\n", -status);
 278                         switch (status) {
 279                         case -EPROTONOSUPPORT:
 280                                 status = -EINVAL;
 281                                 break;
 282                         case -ECONNREFUSED:
 283                         case -ETIMEDOUT:
 284                         case -ENOTCONN:
 285                                 nlm_rebind_host(host);
 286                                 status = -EAGAIN;
 287                                 break;
 288                         case -ERESTARTSYS:
 289                                 return signalled () ? -EINTR : status;
 290                         default:
 291                                 break;
 292                         }
 293                         break;
 294                 } else
 295                 if (resp->status == nlm_lck_denied_grace_period) {
 296                         dprintk("lockd: server in grace period\n");
 297                         if (argp->reclaim) {
 298                                 printk(KERN_WARNING
 299                                      "lockd: spurious grace period reject?!\n");
 300                                 return -ENOLCK;
 301                         }
 302                 } else {
 303                         if (!argp->reclaim) {
 304                                 /* We appear to be out of the grace period */
 305                                 wake_up_all(&host->h_gracewait);
 306                         }
 307                         dprintk("lockd: server returns status %d\n", resp->status);
 308                         return 0;       /* Okay, call complete */
 309                 }
 310
 311 in_grace_period:
 312                 /*
 313                  * The server has rebooted and appears to be in the grace
 314                  * period during which locks are only allowed to be
 315                  * reclaimed.
 316                  * We can only back off and try again later.
 317                  */
 318                 status = nlm_wait_on_grace(&host->h_gracewait);
 319         } while (status == 0);
 320
 321         return status;
 322 }
 323
 324 /*
 325  * Generic NLM call, async version.
 326  */
 327 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 328 {
 329         struct nlm_host *host = req->a_host;
 330         struct rpc_clnt *clnt;
 331         struct rpc_task_setup task_setup_data = {
 332                 .rpc_message = msg,
 333                 .callback_ops = tk_ops,
 334                 .callback_data = req,
 335                 .flags = RPC_TASK_ASYNC,
 336         };
 337
 338         dprintk("lockd: call procedure %d on %s (async)\n",
 339                         (int)proc, host->h_name);
 340
 341         /* If we have no RPC client yet, create one. */
 342         clnt = nlm_bind_host(host);
 343         if (clnt == NULL)
 344                 goto out_err;
 345         msg->rpc_proc = &clnt->cl_procinfo[proc];
 346         task_setup_data.rpc_client = clnt;
 347
 348         /* bootstrap and kick off the async RPC call */
 349         return rpc_run_task(&task_setup_data);
 350 out_err:
 351         tk_ops->rpc_release(req);
 352         return ERR_PTR(-ENOLCK);
 353 }
 354
 355 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 356 {
 357         struct rpc_task *task;
 358
 359         task = __nlm_async_call(req, proc, msg, tk_ops);
 360         if (IS_ERR(task))
 361                 return PTR_ERR(task);
 362         rpc_put_task(task);
 363         return 0;
 364 }
 365
 366 /*
 367  * NLM asynchronous call.
 368  */
 369 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 370 {
 371         struct rpc_message msg = {
 372                 .rpc_argp       = &req->a_args,
 373                 .rpc_resp       = &req->a_res,
 374         };
 375         return nlm_do_async_call(req, proc, &msg, tk_ops);
 376 }
 377
 378 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 379 {
 380         struct rpc_message msg = {
 381                 .rpc_argp       = &req->a_res,
 382         };
 383         return nlm_do_async_call(req, proc, &msg, tk_ops);
 384 }
 385
 386 /*
 387  * NLM client asynchronous call.
 388  *
 389  * Note that although the calls are asynchronous, and are therefore
 390  *      guaranteed to complete, we still always attempt to wait for
 391  *      completion in order to be able to correctly track the lock
 392  *      state.
 393  */
 394 static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 395 {
 396         struct rpc_message msg = {
 397                 .rpc_argp       = &req->a_args,
 398                 .rpc_resp       = &req->a_res,
 399                 .rpc_cred       = cred,
 400         };
 401         struct rpc_task *task;
 402         int err;
 403
 404         task = __nlm_async_call(req, proc, &msg, tk_ops);
 405         if (IS_ERR(task))
 406                 return PTR_ERR(task);
 407         err = rpc_wait_for_completion_task(task);
 408         rpc_put_task(task);
 409         return err;
 410 }
 411
 412 /*
 413  * TEST for the presence of a conflicting lock
 414  */
 415 static int
 416 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 417 {
 418         int     status;
 419
 420         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 421         if (status < 0)
 422                 goto out;
 423
 424         switch (req->a_res.status) {
 425                 case nlm_granted:
 426                         fl->fl_type = F_UNLCK;
 427                         break;
 428                 case nlm_lck_denied:
 429                         /*
 430                          * Report the conflicting lock back to the application.
 431                          */
 432                         fl->fl_start = req->a_res.lock.fl.fl_start;
 433                         fl->fl_end = req->a_res.lock.fl.fl_start;
 434                         fl->fl_type = req->a_res.lock.fl.fl_type;
 435                         fl->fl_pid = 0;
 436                         break;
 437                 default:
 438                         status = nlm_stat_to_errno(req->a_res.status);
 439         }
 440 out:
 441         nlm_release_call(req);
 442         return status;
 443 }
 444
 445 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 446 {
 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 }
 451
 452 static void nlmclnt_locks_release_private(struct file_lock *fl)
 453 {
 454         list_del(&fl->fl_u.nfs_fl.list);
 455         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 456 }
 457
 458 static struct file_lock_operations nlmclnt_lock_ops = {
 459         .fl_copy_lock = nlmclnt_locks_copy_lock,
 460         .fl_release_private = nlmclnt_locks_release_private,
 461 };
 462
 463 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 464 {
 465         BUG_ON(fl->fl_ops != NULL);
 466         fl->fl_u.nfs_fl.state = 0;
 467         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 468         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 469         fl->fl_ops = &nlmclnt_lock_ops;
 470 }
 471
 472 static int do_vfs_lock(struct file_lock *fl)
 473 {
 474         int res = 0;
 475         switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
 476                 case FL_POSIX:
 477                         res = posix_lock_file_wait(fl->fl_file, fl);
 478                         break;
 479                 case FL_FLOCK:
 480                         res = flock_lock_file_wait(fl->fl_file, fl);
 481                         break;
 482                 default:
 483                         BUG();
 484         }
 485         return res;
 486 }
 487
 488 /*
 489  * LOCK: Try to create a lock
 490  *
 491  *                      Programmer Harassment Alert
 492  *
 493  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 494  * will faithfully return LCK_BLOCKED but never cares to notify us when
 495  * the lock could be granted. This way, our local process could hang
 496  * around forever waiting for the callback.
 497  *
 498  *  Solution A: Implement busy-waiting
 499  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 500  *
 501  * For now I am implementing solution A, because I hate the idea of
 502  * re-implementing lockd for a third time in two months. The async
 503  * calls shouldn't be too hard to do, however.
 504  *
 505  * This is one of the lovely things about standards in the NFS area:
 506  * they're so soft and squishy you can't really blame HP for doing this.
 507  */
 508 static int
 509 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 510 {
 511         struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
 512         struct nlm_host *host = req->a_host;
 513         struct nlm_res  *resp = &req->a_res;
 514         struct nlm_wait *block = NULL;
 515         unsigned char fl_flags = fl->fl_flags;
 516         unsigned char fl_type;
 517         int status = -ENOLCK;
 518
 519         if (nsm_monitor(host) < 0) {
 520                 printk(KERN_NOTICE "lockd: failed to monitor %s\n",
 521                                         host->h_name);
 522                 goto out;
 523         }
 524         fl->fl_flags |= FL_ACCESS;
 525         status = do_vfs_lock(fl);
 526         fl->fl_flags = fl_flags;
 527         if (status < 0)
 528                 goto out;
 529
 530         block = nlmclnt_prepare_block(host, fl);
 531 again:
 532         /*
 533          * Initialise resp->status to a valid non-zero value,
 534          * since 0 == nlm_lck_granted
 535          */
 536         resp->status = nlm_lck_blocked;
 537         for(;;) {
 538                 /* Reboot protection */
 539                 fl->fl_u.nfs_fl.state = host->h_state;
 540                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 541                 if (status < 0)
 542                         break;
 543                 /* Did a reclaimer thread notify us of a server reboot? */
 544                 if (resp->status ==  nlm_lck_denied_grace_period)
 545                         continue;
 546                 if (resp->status != nlm_lck_blocked)
 547                         break;
 548                 /* Wait on an NLM blocking lock */
 549                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 550                 if (status < 0)
 551                         break;
 552                 if (resp->status != nlm_lck_blocked)
 553                         break;
 554         }
 555
 556         /* if we were interrupted while blocking, then cancel the lock request
 557          * and exit
 558          */
 559         if (resp->status == nlm_lck_blocked) {
 560                 if (!req->a_args.block)
 561                         goto out_unlock;
 562                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 563                         goto out_unblock;
 564         }
 565
 566         if (resp->status == nlm_granted) {
 567                 down_read(&host->h_rwsem);
 568                 /* Check whether or not the server has rebooted */
 569                 if (fl->fl_u.nfs_fl.state != host->h_state) {
 570                         up_read(&host->h_rwsem);
 571                         goto again;
 572                 }
 573                 /* Ensure the resulting lock will get added to granted list */
 574                 fl->fl_flags |= FL_SLEEP;
 575                 if (do_vfs_lock(fl) < 0)
 576                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 577                 up_read(&host->h_rwsem);
 578                 fl->fl_flags = fl_flags;
 579                 status = 0;
 580         }
 581         if (status < 0)
 582                 goto out_unlock;
 583         status = nlm_stat_to_errno(resp->status);
 584 out_unblock:
 585         nlmclnt_finish_block(block);
 586 out:
 587         nlm_release_call(req);
 588         return status;
 589 out_unlock:
 590         /* Fatal error: ensure that we remove the lock altogether */
 591         dprintk("lockd: lock attempt ended in fatal error.\n"
 592                 "       Attempting to unlock.\n");
 593         nlmclnt_finish_block(block);
 594         fl_type = fl->fl_type;
 595         fl->fl_type = F_UNLCK;
 596         down_read(&host->h_rwsem);
 597         do_vfs_lock(fl);
 598         up_read(&host->h_rwsem);
 599         fl->fl_type = fl_type;
 600         fl->fl_flags = fl_flags;
 601         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 602         return status;
 603 }
 604
 605 /*
 606  * RECLAIM: Try to reclaim a lock
 607  */
 608 int
 609 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
 610 {
 611         struct nlm_rqst reqst, *req;
 612         int             status;
 613
 614         req = &reqst;
 615         memset(req, 0, sizeof(*req));
 616         locks_init_lock(&req->a_args.lock.fl);
 617         locks_init_lock(&req->a_res.lock.fl);
 618         req->a_host  = host;
 619         req->a_flags = 0;
 620
 621         /* Set up the argument struct */
 622         nlmclnt_setlockargs(req, fl);
 623         req->a_args.reclaim = 1;
 624
 625         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 626         if (status >= 0 && req->a_res.status == nlm_granted)
 627                 return 0;
 628
 629         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 630                                 "(errno %d, status %d)\n", fl->fl_pid,
 631                                 status, ntohl(req->a_res.status));
 632
 633         /*
 634          * FIXME: This is a serious failure. We can
 635          *
 636          *  a.  Ignore the problem
 637          *  b.  Send the owning process some signal (Linux doesn't have
 638          *      SIGLOST, though...)
 639          *  c.  Retry the operation
 640          *
 641          * Until someone comes up with a simple implementation
 642          * for b or c, I'll choose option a.
 643          */
 644
 645         return -ENOLCK;
 646 }
 647
 648 /*
 649  * UNLOCK: remove an existing lock
 650  */
 651 static int
 652 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 653 {
 654         struct nlm_host *host = req->a_host;
 655         struct nlm_res  *resp = &req->a_res;
 656         int status;
 657         unsigned char fl_flags = fl->fl_flags;
 658
 659         /*
 660          * Note: the server is supposed to either grant us the unlock
 661          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 662          * case, we want to unlock.
 663          */
 664         fl->fl_flags |= FL_EXISTS;
 665         down_read(&host->h_rwsem);
 666         status = do_vfs_lock(fl);
 667         up_read(&host->h_rwsem);
 668         fl->fl_flags = fl_flags;
 669         if (status == -ENOENT) {
 670                 status = 0;
 671                 goto out;
 672         }
 673
 674         atomic_inc(&req->a_count);
 675         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 676                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 677         if (status < 0)
 678                 goto out;
 679
 680         if (resp->status == nlm_granted)
 681                 goto out;
 682
 683         if (resp->status != nlm_lck_denied_nolocks)
 684                 printk("lockd: unexpected unlock status: %d\n", resp->status);
 685         /* What to do now? I'm out of my depth... */
 686         status = -ENOLCK;
 687 out:
 688         nlm_release_call(req);
 689         return status;
 690 }
 691
 692 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 693 {
 694         struct nlm_rqst *req = data;
 695         u32 status = ntohl(req->a_res.status);
 696
 697         if (RPC_ASSASSINATED(task))
 698                 goto die;
 699
 700         if (task->tk_status < 0) {
 701                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 702                 goto retry_rebind;
 703         }
 704         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 705                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 706                 goto retry_unlock;
 707         }
 708         if (status != NLM_LCK_GRANTED)
 709                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 710 die:
 711         return;
 712  retry_rebind:
 713         nlm_rebind_host(req->a_host);
 714  retry_unlock:
 715         rpc_restart_call(task);
 716 }
 717
 718 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 719         .rpc_call_done = nlmclnt_unlock_callback,
 720         .rpc_release = nlmclnt_rpc_release,
 721 };
 722
 723 /*
 724  * Cancel a blocked lock request.
 725  * We always use an async RPC call for this in order not to hang a
 726  * process that has been Ctrl-C'ed.
 727  */
 728 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 729 {
 730         struct nlm_rqst *req;
 731         int status;
 732
 733         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 734                 "       Attempting to cancel lock.\n");
 735
 736         req = nlm_alloc_call(nlm_get_host(host));
 737         if (!req)
 738                 return -ENOMEM;
 739         req->a_flags = RPC_TASK_ASYNC;
 740
 741         nlmclnt_setlockargs(req, fl);
 742         req->a_args.block = block;
 743
 744         atomic_inc(&req->a_count);
 745         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 746                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 747         if (status == 0 && req->a_res.status == nlm_lck_denied)
 748                 status = -ENOLCK;
 749         nlm_release_call(req);
 750         return status;
 751 }
 752
 753 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 754 {
 755         struct nlm_rqst *req = data;
 756         u32 status = ntohl(req->a_res.status);
 757
 758         if (RPC_ASSASSINATED(task))
 759                 goto die;
 760
 761         if (task->tk_status < 0) {
 762                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 763                                         task->tk_status);
 764                 goto retry_cancel;
 765         }
 766
 767         dprintk("lockd: cancel status %u (task %u)\n",
 768                         status, task->tk_pid);
 769
 770         switch (status) {
 771         case NLM_LCK_GRANTED:
 772         case NLM_LCK_DENIED_GRACE_PERIOD:
 773         case NLM_LCK_DENIED:
 774                 /* Everything's good */
 775                 break;
 776         case NLM_LCK_DENIED_NOLOCKS:
 777                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 778                 goto retry_cancel;
 779         default:
 780                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 781                         status);
 782         }
 783
 784 die:
 785         return;
 786
 787 retry_cancel:
 788         /* Don't ever retry more than 3 times */
 789         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 790                 goto die;
 791         nlm_rebind_host(req->a_host);
 792         rpc_restart_call(task);
 793         rpc_delay(task, 30 * HZ);
 794 }
 795
 796 static const struct rpc_call_ops nlmclnt_cancel_ops = {
 797         .rpc_call_done = nlmclnt_cancel_callback,
 798         .rpc_release = nlmclnt_rpc_release,
 799 };
 800
 801 /*
 802  * Convert an NLM status code to a generic kernel errno
 803  */
 804 static int
 805 nlm_stat_to_errno(__be32 status)
 806 {
 807         switch(ntohl(status)) {
 808         case NLM_LCK_GRANTED:
 809                 return 0;
 810         case NLM_LCK_DENIED:
 811                 return -EAGAIN;
 812         case NLM_LCK_DENIED_NOLOCKS:
 813         case NLM_LCK_DENIED_GRACE_PERIOD:
 814                 return -ENOLCK;
 815         case NLM_LCK_BLOCKED:
 816                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 817                 return -ENOLCK;
 818 #ifdef CONFIG_LOCKD_V4
 819         case NLM_DEADLCK:
 820                 return -EDEADLK;
 821         case NLM_ROFS:
 822                 return -EROFS;
 823         case NLM_STALE_FH:
 824                 return -ESTALE;
 825         case NLM_FBIG:
 826                 return -EOVERFLOW;
 827         case NLM_FAILED:
 828                 return -ENOLCK;
 829 #endif
 830         }
 831         printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
 832         return -ENOLCK;
 833 }