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         refcount_inc(&lockowner->count);
  52         return lockowner;
  53 }
  54
  55 static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
  56 {
  57         if (!refcount_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                         refcount_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         char *nodename = req->a_host->h_rpcclnt->cl_nodename;
 129
 130         nlmclnt_next_cookie(&argp->cookie);
 131         memcpy(&lock->fh, NFS_FH(file_inode(fl->fl_file)), sizeof(struct nfs_fh));
 132         lock->caller  = 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                                 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         WARN_ON_ONCE(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  * @data: address of data to be sent to callback operations
 154  *
 155  */
 156 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data)
 157 {
 158         struct nlm_rqst         *call;
 159         int                     status;
 160         const struct nlmclnt_operations *nlmclnt_ops = host->h_nlmclnt_ops;
 161
 162         call = nlm_alloc_call(host);
 163         if (call == NULL)
 164                 return -ENOMEM;
 165
 166         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_alloc_call)
 167                 nlmclnt_ops->nlmclnt_alloc_call(data);
 168
 169         nlmclnt_locks_init_private(fl, host);
 170         if (!fl->fl_u.nfs_fl.owner) {
 171                 /* lockowner allocation has failed */
 172                 nlmclnt_release_call(call);
 173                 return -ENOMEM;
 174         }
 175         /* Set up the argument struct */
 176         nlmclnt_setlockargs(call, fl);
 177         call->a_callback_data = data;
 178
 179         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 180                 if (fl->fl_type != F_UNLCK) {
 181                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 182                         status = nlmclnt_lock(call, fl);
 183                 } else
 184                         status = nlmclnt_unlock(call, fl);
 185         } else if (IS_GETLK(cmd))
 186                 status = nlmclnt_test(call, fl);
 187         else
 188                 status = -EINVAL;
 189         fl->fl_ops->fl_release_private(fl);
 190         fl->fl_ops = NULL;
 191
 192         dprintk("lockd: clnt proc returns %d\n", status);
 193         return status;
 194 }
 195 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 196
 197 /*
 198  * Allocate an NLM RPC call struct
 199  */
 200 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 201 {
 202         struct nlm_rqst *call;
 203
 204         for(;;) {
 205                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 206                 if (call != NULL) {
 207                         refcount_set(&call->a_count, 1);
 208                         locks_init_lock(&call->a_args.lock.fl);
 209                         locks_init_lock(&call->a_res.lock.fl);
 210                         call->a_host = nlm_get_host(host);
 211                         return call;
 212                 }
 213                 if (signalled())
 214                         break;
 215                 printk("nlm_alloc_call: failed, waiting for memory\n");
 216                 schedule_timeout_interruptible(5*HZ);
 217         }
 218         return NULL;
 219 }
 220
 221 void nlmclnt_release_call(struct nlm_rqst *call)
 222 {
 223         const struct nlmclnt_operations *nlmclnt_ops = call->a_host->h_nlmclnt_ops;
 224
 225         if (!refcount_dec_and_test(&call->a_count))
 226                 return;
 227         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_release_call)
 228                 nlmclnt_ops->nlmclnt_release_call(call->a_callback_data);
 229         nlmclnt_release_host(call->a_host);
 230         nlmclnt_release_lockargs(call);
 231         kfree(call);
 232 }
 233
 234 static void nlmclnt_rpc_release(void *data)
 235 {
 236         nlmclnt_release_call(data);
 237 }
 238
 239 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 240 {
 241         DEFINE_WAIT(wait);
 242         int status = -EINTR;
 243
 244         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 245         if (!signalled ()) {
 246                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 247                 try_to_freeze();
 248                 if (!signalled ())
 249                         status = 0;
 250         }
 251         finish_wait(queue, &wait);
 252         return status;
 253 }
 254
 255 /*
 256  * Generic NLM call
 257  */
 258 static int
 259 nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc)
 260 {
 261         struct nlm_host *host = req->a_host;
 262         struct rpc_clnt *clnt;
 263         struct nlm_args *argp = &req->a_args;
 264         struct nlm_res  *resp = &req->a_res;
 265         struct rpc_message msg = {
 266                 .rpc_argp       = argp,
 267                 .rpc_resp       = resp,
 268                 .rpc_cred       = cred,
 269         };
 270         int             status;
 271
 272         dprintk("lockd: call procedure %d on %s\n",
 273                         (int)proc, host->h_name);
 274
 275         do {
 276                 if (host->h_reclaiming && !argp->reclaim)
 277                         goto in_grace_period;
 278
 279                 /* If we have no RPC client yet, create one. */
 280                 if ((clnt = nlm_bind_host(host)) == NULL)
 281                         return -ENOLCK;
 282                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 283
 284                 /* Perform the RPC call. If an error occurs, try again */
 285                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 286                         dprintk("lockd: rpc_call returned error %d\n", -status);
 287                         switch (status) {
 288                         case -EPROTONOSUPPORT:
 289                                 status = -EINVAL;
 290                                 break;
 291                         case -ECONNREFUSED:
 292                         case -ETIMEDOUT:
 293                         case -ENOTCONN:
 294                                 nlm_rebind_host(host);
 295                                 status = -EAGAIN;
 296                                 break;
 297                         case -ERESTARTSYS:
 298                                 return signalled () ? -EINTR : status;
 299                         default:
 300                                 break;
 301                         }
 302                         break;
 303                 } else
 304                 if (resp->status == nlm_lck_denied_grace_period) {
 305                         dprintk("lockd: server in grace period\n");
 306                         if (argp->reclaim) {
 307                                 printk(KERN_WARNING
 308                                      "lockd: spurious grace period reject?!\n");
 309                                 return -ENOLCK;
 310                         }
 311                 } else {
 312                         if (!argp->reclaim) {
 313                                 /* We appear to be out of the grace period */
 314                                 wake_up_all(&host->h_gracewait);
 315                         }
 316                         dprintk("lockd: server returns status %d\n",
 317                                 ntohl(resp->status));
 318                         return 0;       /* Okay, call complete */
 319                 }
 320
 321 in_grace_period:
 322                 /*
 323                  * The server has rebooted and appears to be in the grace
 324                  * period during which locks are only allowed to be
 325                  * reclaimed.
 326                  * We can only back off and try again later.
 327                  */
 328                 status = nlm_wait_on_grace(&host->h_gracewait);
 329         } while (status == 0);
 330
 331         return status;
 332 }
 333
 334 /*
 335  * Generic NLM call, async version.
 336  */
 337 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 338 {
 339         struct nlm_host *host = req->a_host;
 340         struct rpc_clnt *clnt;
 341         struct rpc_task_setup task_setup_data = {
 342                 .rpc_message = msg,
 343                 .callback_ops = tk_ops,
 344                 .callback_data = req,
 345                 .flags = RPC_TASK_ASYNC,
 346         };
 347
 348         dprintk("lockd: call procedure %d on %s (async)\n",
 349                         (int)proc, host->h_name);
 350
 351         /* If we have no RPC client yet, create one. */
 352         clnt = nlm_bind_host(host);
 353         if (clnt == NULL)
 354                 goto out_err;
 355         msg->rpc_proc = &clnt->cl_procinfo[proc];
 356         task_setup_data.rpc_client = clnt;
 357
 358         /* bootstrap and kick off the async RPC call */
 359         return rpc_run_task(&task_setup_data);
 360 out_err:
 361         tk_ops->rpc_release(req);
 362         return ERR_PTR(-ENOLCK);
 363 }
 364
 365 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 366 {
 367         struct rpc_task *task;
 368
 369         task = __nlm_async_call(req, proc, msg, tk_ops);
 370         if (IS_ERR(task))
 371                 return PTR_ERR(task);
 372         rpc_put_task(task);
 373         return 0;
 374 }
 375
 376 /*
 377  * NLM asynchronous call.
 378  */
 379 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 380 {
 381         struct rpc_message msg = {
 382                 .rpc_argp       = &req->a_args,
 383                 .rpc_resp       = &req->a_res,
 384         };
 385         return nlm_do_async_call(req, proc, &msg, tk_ops);
 386 }
 387
 388 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 389 {
 390         struct rpc_message msg = {
 391                 .rpc_argp       = &req->a_res,
 392         };
 393         return nlm_do_async_call(req, proc, &msg, tk_ops);
 394 }
 395
 396 /*
 397  * NLM client asynchronous call.
 398  *
 399  * Note that although the calls are asynchronous, and are therefore
 400  *      guaranteed to complete, we still always attempt to wait for
 401  *      completion in order to be able to correctly track the lock
 402  *      state.
 403  */
 404 static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 405 {
 406         struct rpc_message msg = {
 407                 .rpc_argp       = &req->a_args,
 408                 .rpc_resp       = &req->a_res,
 409                 .rpc_cred       = cred,
 410         };
 411         struct rpc_task *task;
 412         int err;
 413
 414         task = __nlm_async_call(req, proc, &msg, tk_ops);
 415         if (IS_ERR(task))
 416                 return PTR_ERR(task);
 417         err = rpc_wait_for_completion_task(task);
 418         rpc_put_task(task);
 419         return err;
 420 }
 421
 422 /*
 423  * TEST for the presence of a conflicting lock
 424  */
 425 static int
 426 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 427 {
 428         int     status;
 429
 430         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 431         if (status < 0)
 432                 goto out;
 433
 434         switch (req->a_res.status) {
 435                 case nlm_granted:
 436                         fl->fl_type = F_UNLCK;
 437                         break;
 438                 case nlm_lck_denied:
 439                         /*
 440                          * Report the conflicting lock back to the application.
 441                          */
 442                         fl->fl_start = req->a_res.lock.fl.fl_start;
 443                         fl->fl_end = req->a_res.lock.fl.fl_end;
 444                         fl->fl_type = req->a_res.lock.fl.fl_type;
 445                         fl->fl_pid = 0;
 446                         break;
 447                 default:
 448                         status = nlm_stat_to_errno(req->a_res.status);
 449         }
 450 out:
 451         nlmclnt_release_call(req);
 452         return status;
 453 }
 454
 455 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 456 {
 457         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 458         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 459         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
 460         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 461         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 462 }
 463
 464 static void nlmclnt_locks_release_private(struct file_lock *fl)
 465 {
 466         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 467         list_del(&fl->fl_u.nfs_fl.list);
 468         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 469         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 470 }
 471
 472 static const struct file_lock_operations nlmclnt_lock_ops = {
 473         .fl_copy_lock = nlmclnt_locks_copy_lock,
 474         .fl_release_private = nlmclnt_locks_release_private,
 475 };
 476
 477 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 478 {
 479         fl->fl_u.nfs_fl.state = 0;
 480         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 481         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 482         fl->fl_ops = &nlmclnt_lock_ops;
 483 }
 484
 485 static int do_vfs_lock(struct file_lock *fl)
 486 {
 487         return locks_lock_file_wait(fl->fl_file, fl);
 488 }
 489
 490 /*
 491  * LOCK: Try to create a lock
 492  *
 493  *                      Programmer Harassment Alert
 494  *
 495  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 496  * will faithfully return LCK_BLOCKED but never cares to notify us when
 497  * the lock could be granted. This way, our local process could hang
 498  * around forever waiting for the callback.
 499  *
 500  *  Solution A: Implement busy-waiting
 501  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 502  *
 503  * For now I am implementing solution A, because I hate the idea of
 504  * re-implementing lockd for a third time in two months. The async
 505  * calls shouldn't be too hard to do, however.
 506  *
 507  * This is one of the lovely things about standards in the NFS area:
 508  * they're so soft and squishy you can't really blame HP for doing this.
 509  */
 510 static int
 511 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 512 {
 513         struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
 514         struct nlm_host *host = req->a_host;
 515         struct nlm_res  *resp = &req->a_res;
 516         struct nlm_wait *block = NULL;
 517         unsigned char fl_flags = fl->fl_flags;
 518         unsigned char fl_type;
 519         int status = -ENOLCK;
 520
 521         if (nsm_monitor(host) < 0)
 522                 goto out;
 523         req->a_args.state = nsm_local_state;
 524
 525         fl->fl_flags |= FL_ACCESS;
 526         status = do_vfs_lock(fl);
 527         fl->fl_flags = fl_flags;
 528         if (status < 0)
 529                 goto out;
 530
 531         block = nlmclnt_prepare_block(host, fl);
 532 again:
 533         /*
 534          * Initialise resp->status to a valid non-zero value,
 535          * since 0 == nlm_lck_granted
 536          */
 537         resp->status = nlm_lck_blocked;
 538         for(;;) {
 539                 /* Reboot protection */
 540                 fl->fl_u.nfs_fl.state = host->h_state;
 541                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 542                 if (status < 0)
 543                         break;
 544                 /* Did a reclaimer thread notify us of a server reboot? */
 545                 if (resp->status ==  nlm_lck_denied_grace_period)
 546                         continue;
 547                 if (resp->status != nlm_lck_blocked)
 548                         break;
 549                 /* Wait on an NLM blocking lock */
 550                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 551                 if (status < 0)
 552                         break;
 553                 if (resp->status != nlm_lck_blocked)
 554                         break;
 555         }
 556
 557         /* if we were interrupted while blocking, then cancel the lock request
 558          * and exit
 559          */
 560         if (resp->status == nlm_lck_blocked) {
 561                 if (!req->a_args.block)
 562                         goto out_unlock;
 563                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 564                         goto out_unblock;
 565         }
 566
 567         if (resp->status == nlm_granted) {
 568                 down_read(&host->h_rwsem);
 569                 /* Check whether or not the server has rebooted */
 570                 if (fl->fl_u.nfs_fl.state != host->h_state) {
 571                         up_read(&host->h_rwsem);
 572                         goto again;
 573                 }
 574                 /* Ensure the resulting lock will get added to granted list */
 575                 fl->fl_flags |= FL_SLEEP;
 576                 if (do_vfs_lock(fl) < 0)
 577                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 578                 up_read(&host->h_rwsem);
 579                 fl->fl_flags = fl_flags;
 580                 status = 0;
 581         }
 582         if (status < 0)
 583                 goto out_unlock;
 584         /*
 585          * EAGAIN doesn't make sense for sleeping locks, and in some
 586          * cases NLM_LCK_DENIED is returned for a permanent error.  So
 587          * turn it into an ENOLCK.
 588          */
 589         if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
 590                 status = -ENOLCK;
 591         else
 592                 status = nlm_stat_to_errno(resp->status);
 593 out_unblock:
 594         nlmclnt_finish_block(block);
 595 out:
 596         nlmclnt_release_call(req);
 597         return status;
 598 out_unlock:
 599         /* Fatal error: ensure that we remove the lock altogether */
 600         dprintk("lockd: lock attempt ended in fatal error.\n"
 601                 "       Attempting to unlock.\n");
 602         nlmclnt_finish_block(block);
 603         fl_type = fl->fl_type;
 604         fl->fl_type = F_UNLCK;
 605         down_read(&host->h_rwsem);
 606         do_vfs_lock(fl);
 607         up_read(&host->h_rwsem);
 608         fl->fl_type = fl_type;
 609         fl->fl_flags = fl_flags;
 610         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 611         return status;
 612 }
 613
 614 /*
 615  * RECLAIM: Try to reclaim a lock
 616  */
 617 int
 618 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
 619                 struct nlm_rqst *req)
 620 {
 621         int             status;
 622
 623         memset(req, 0, sizeof(*req));
 624         locks_init_lock(&req->a_args.lock.fl);
 625         locks_init_lock(&req->a_res.lock.fl);
 626         req->a_host  = host;
 627
 628         /* Set up the argument struct */
 629         nlmclnt_setlockargs(req, fl);
 630         req->a_args.reclaim = 1;
 631
 632         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 633         if (status >= 0 && req->a_res.status == nlm_granted)
 634                 return 0;
 635
 636         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 637                                 "(errno %d, status %d)\n", fl->fl_pid,
 638                                 status, ntohl(req->a_res.status));
 639
 640         /*
 641          * FIXME: This is a serious failure. We can
 642          *
 643          *  a.  Ignore the problem
 644          *  b.  Send the owning process some signal (Linux doesn't have
 645          *      SIGLOST, though...)
 646          *  c.  Retry the operation
 647          *
 648          * Until someone comes up with a simple implementation
 649          * for b or c, I'll choose option a.
 650          */
 651
 652         return -ENOLCK;
 653 }
 654
 655 /*
 656  * UNLOCK: remove an existing lock
 657  */
 658 static int
 659 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 660 {
 661         struct nlm_host *host = req->a_host;
 662         struct nlm_res  *resp = &req->a_res;
 663         int status;
 664         unsigned char fl_flags = fl->fl_flags;
 665
 666         /*
 667          * Note: the server is supposed to either grant us the unlock
 668          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 669          * case, we want to unlock.
 670          */
 671         fl->fl_flags |= FL_EXISTS;
 672         down_read(&host->h_rwsem);
 673         status = do_vfs_lock(fl);
 674         up_read(&host->h_rwsem);
 675         fl->fl_flags = fl_flags;
 676         if (status == -ENOENT) {
 677                 status = 0;
 678                 goto out;
 679         }
 680
 681         refcount_inc(&req->a_count);
 682         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 683                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 684         if (status < 0)
 685                 goto out;
 686
 687         if (resp->status == nlm_granted)
 688                 goto out;
 689
 690         if (resp->status != nlm_lck_denied_nolocks)
 691                 printk("lockd: unexpected unlock status: %d\n",
 692                         ntohl(resp->status));
 693         /* What to do now? I'm out of my depth... */
 694         status = -ENOLCK;
 695 out:
 696         nlmclnt_release_call(req);
 697         return status;
 698 }
 699
 700 static void nlmclnt_unlock_prepare(struct rpc_task *task, void *data)
 701 {
 702         struct nlm_rqst *req = data;
 703         const struct nlmclnt_operations *nlmclnt_ops = req->a_host->h_nlmclnt_ops;
 704         bool defer_call = false;
 705
 706         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_unlock_prepare)
 707                 defer_call = nlmclnt_ops->nlmclnt_unlock_prepare(task, req->a_callback_data);
 708
 709         if (!defer_call)
 710                 rpc_call_start(task);
 711 }
 712
 713 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 714 {
 715         struct nlm_rqst *req = data;
 716         u32 status = ntohl(req->a_res.status);
 717
 718         if (RPC_ASSASSINATED(task))
 719                 goto die;
 720
 721         if (task->tk_status < 0) {
 722                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 723                 switch (task->tk_status) {
 724                 case -EACCES:
 725                 case -EIO:
 726                         goto die;
 727                 default:
 728                         goto retry_rebind;
 729                 }
 730         }
 731         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 732                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 733                 goto retry_unlock;
 734         }
 735         if (status != NLM_LCK_GRANTED)
 736                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 737 die:
 738         return;
 739  retry_rebind:
 740         nlm_rebind_host(req->a_host);
 741  retry_unlock:
 742         rpc_restart_call(task);
 743 }
 744
 745 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 746         .rpc_call_prepare = nlmclnt_unlock_prepare,
 747         .rpc_call_done = nlmclnt_unlock_callback,
 748         .rpc_release = nlmclnt_rpc_release,
 749 };
 750
 751 /*
 752  * Cancel a blocked lock request.
 753  * We always use an async RPC call for this in order not to hang a
 754  * process that has been Ctrl-C'ed.
 755  */
 756 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 757 {
 758         struct nlm_rqst *req;
 759         int status;
 760
 761         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 762                 "       Attempting to cancel lock.\n");
 763
 764         req = nlm_alloc_call(host);
 765         if (!req)
 766                 return -ENOMEM;
 767         req->a_flags = RPC_TASK_ASYNC;
 768
 769         nlmclnt_setlockargs(req, fl);
 770         req->a_args.block = block;
 771
 772         refcount_inc(&req->a_count);
 773         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 774                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 775         if (status == 0 && req->a_res.status == nlm_lck_denied)
 776                 status = -ENOLCK;
 777         nlmclnt_release_call(req);
 778         return status;
 779 }
 780
 781 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 782 {
 783         struct nlm_rqst *req = data;
 784         u32 status = ntohl(req->a_res.status);
 785
 786         if (RPC_ASSASSINATED(task))
 787                 goto die;
 788
 789         if (task->tk_status < 0) {
 790                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 791                                         task->tk_status);
 792                 goto retry_cancel;
 793         }
 794
 795         dprintk("lockd: cancel status %u (task %u)\n",
 796                         status, task->tk_pid);
 797
 798         switch (status) {
 799         case NLM_LCK_GRANTED:
 800         case NLM_LCK_DENIED_GRACE_PERIOD:
 801         case NLM_LCK_DENIED:
 802                 /* Everything's good */
 803                 break;
 804         case NLM_LCK_DENIED_NOLOCKS:
 805                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 806                 goto retry_cancel;
 807         default:
 808                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 809                         status);
 810         }
 811
 812 die:
 813         return;
 814
 815 retry_cancel:
 816         /* Don't ever retry more than 3 times */
 817         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 818                 goto die;
 819         nlm_rebind_host(req->a_host);
 820         rpc_restart_call(task);
 821         rpc_delay(task, 30 * HZ);
 822 }
 823
 824 static const struct rpc_call_ops nlmclnt_cancel_ops = {
 825         .rpc_call_done = nlmclnt_cancel_callback,
 826         .rpc_release = nlmclnt_rpc_release,
 827 };
 828
 829 /*
 830  * Convert an NLM status code to a generic kernel errno
 831  */
 832 static int
 833 nlm_stat_to_errno(__be32 status)
 834 {
 835         switch(ntohl(status)) {
 836         case NLM_LCK_GRANTED:
 837                 return 0;
 838         case NLM_LCK_DENIED:
 839                 return -EAGAIN;
 840         case NLM_LCK_DENIED_NOLOCKS:
 841         case NLM_LCK_DENIED_GRACE_PERIOD:
 842                 return -ENOLCK;
 843         case NLM_LCK_BLOCKED:
 844                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 845                 return -ENOLCK;
 846 #ifdef CONFIG_LOCKD_V4
 847         case NLM_DEADLCK:
 848                 return -EDEADLK;
 849         case NLM_ROFS:
 850                 return -EROFS;
 851         case NLM_STALE_FH:
 852                 return -ESTALE;
 853         case NLM_FBIG:
 854                 return -EOVERFLOW;
 855         case NLM_FAILED:
 856                 return -ENOLCK;
 857 #endif
 858         }
 859         printk(KERN_NOTICE "lockd: unexpected server status %d\n",
 860                  ntohl(status));
 861         return -ENOLCK;
 862 }