fs/lockd/clntproc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/lockd/clntproc.c
   4  *
   5  * RPC procedures for the client side NLM implementation
   6  *
   7  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/types.h>
  13 #include <linux/errno.h>
  14 #include <linux/fs.h>
  15 #include <linux/nfs_fs.h>
  16 #include <linux/utsname.h>
  17 #include <linux/freezer.h>
  18 #include <linux/sunrpc/clnt.h>
  19 #include <linux/sunrpc/svc.h>
  20 #include <linux/lockd/lockd.h>
  21
  22 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  23 #define NLMCLNT_GRACE_WAIT      (5*HZ)
  24 #define NLMCLNT_POLL_TIMEOUT    (30*HZ)
  25 #define NLMCLNT_MAX_RETRIES     3
  26
  27 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
  28 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
  29 static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
  30 static int      nlm_stat_to_errno(__be32 stat);
  31 static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
  32 static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
  33
  34 static const struct rpc_call_ops nlmclnt_unlock_ops;
  35 static const struct rpc_call_ops nlmclnt_cancel_ops;
  36
  37 /*
  38  * Cookie counter for NLM requests
  39  */
  40 static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
  41
  42 void nlmclnt_next_cookie(struct nlm_cookie *c)
  43 {
  44         u32     cookie = atomic_inc_return(&nlm_cookie);
  45
  46         memcpy(c->data, &cookie, 4);
  47         c->len=4;
  48 }
  49
  50 static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
  51 {
  52         refcount_inc(&lockowner->count);
  53         return lockowner;
  54 }
  55
  56 static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
  57 {
  58         if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
  59                 return;
  60         list_del(&lockowner->list);
  61         spin_unlock(&lockowner->host->h_lock);
  62         nlmclnt_release_host(lockowner->host);
  63         kfree(lockowner);
  64 }
  65
  66 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
  67 {
  68         struct nlm_lockowner *lockowner;
  69         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  70                 if (lockowner->pid == pid)
  71                         return -EBUSY;
  72         }
  73         return 0;
  74 }
  75
  76 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
  77 {
  78         uint32_t res;
  79         do {
  80                 res = host->h_pidcount++;
  81         } while (nlm_pidbusy(host, res) < 0);
  82         return res;
  83 }
  84
  85 static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  86 {
  87         struct nlm_lockowner *lockowner;
  88         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  89                 if (lockowner->owner != owner)
  90                         continue;
  91                 return nlm_get_lockowner(lockowner);
  92         }
  93         return NULL;
  94 }
  95
  96 static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  97 {
  98         struct nlm_lockowner *res, *new = NULL;
  99
 100         spin_lock(&host->h_lock);
 101         res = __nlm_find_lockowner(host, owner);
 102         if (res == NULL) {
 103                 spin_unlock(&host->h_lock);
 104                 new = kmalloc(sizeof(*new), GFP_KERNEL);
 105                 spin_lock(&host->h_lock);
 106                 res = __nlm_find_lockowner(host, owner);
 107                 if (res == NULL && new != NULL) {
 108                         res = new;
 109                         refcount_set(&new->count, 1);
 110                         new->owner = owner;
 111                         new->pid = __nlm_alloc_pid(host);
 112                         new->host = nlm_get_host(host);
 113                         list_add(&new->list, &host->h_lockowners);
 114                         new = NULL;
 115                 }
 116         }
 117         spin_unlock(&host->h_lock);
 118         kfree(new);
 119         return res;
 120 }
 121
 122 /*
 123  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 124  */
 125 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 126 {
 127         struct nlm_args *argp = &req->a_args;
 128         struct nlm_lock *lock = &argp->lock;
 129         char *nodename = req->a_host->h_rpcclnt->cl_nodename;
 130
 131         nlmclnt_next_cookie(&argp->cookie);
 132         memcpy(&lock->fh, NFS_FH(locks_inode(fl->fl_file)), sizeof(struct nfs_fh));
 133         lock->caller  = nodename;
 134         lock->oh.data = req->a_owner;
 135         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
 136                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
 137                                 nodename);
 138         lock->svid = fl->fl_u.nfs_fl.owner->pid;
 139         lock->fl.fl_start = fl->fl_start;
 140         lock->fl.fl_end = fl->fl_end;
 141         lock->fl.fl_type = fl->fl_type;
 142 }
 143
 144 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
 145 {
 146         WARN_ON_ONCE(req->a_args.lock.fl.fl_ops != NULL);
 147 }
 148
 149 /**
 150  * nlmclnt_proc - Perform a single client-side lock request
 151  * @host: address of a valid nlm_host context representing the NLM server
 152  * @cmd: fcntl-style file lock operation to perform
 153  * @fl: address of arguments for the lock operation
 154  * @data: address of data to be sent to callback operations
 155  *
 156  */
 157 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data)
 158 {
 159         struct nlm_rqst         *call;
 160         int                     status;
 161         const struct nlmclnt_operations *nlmclnt_ops = host->h_nlmclnt_ops;
 162
 163         call = nlm_alloc_call(host);
 164         if (call == NULL)
 165                 return -ENOMEM;
 166
 167         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_alloc_call)
 168                 nlmclnt_ops->nlmclnt_alloc_call(data);
 169
 170         nlmclnt_locks_init_private(fl, host);
 171         if (!fl->fl_u.nfs_fl.owner) {
 172                 /* lockowner allocation has failed */
 173                 nlmclnt_release_call(call);
 174                 return -ENOMEM;
 175         }
 176         /* Set up the argument struct */
 177         nlmclnt_setlockargs(call, fl);
 178         call->a_callback_data = data;
 179
 180         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 181                 if (fl->fl_type != F_UNLCK) {
 182                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 183                         status = nlmclnt_lock(call, fl);
 184                 } else
 185                         status = nlmclnt_unlock(call, fl);
 186         } else if (IS_GETLK(cmd))
 187                 status = nlmclnt_test(call, fl);
 188         else
 189                 status = -EINVAL;
 190         fl->fl_ops->fl_release_private(fl);
 191         fl->fl_ops = NULL;
 192
 193         dprintk("lockd: clnt proc returns %d\n", status);
 194         return status;
 195 }
 196 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 197
 198 /*
 199  * Allocate an NLM RPC call struct
 200  */
 201 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 202 {
 203         struct nlm_rqst *call;
 204
 205         for(;;) {
 206                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 207                 if (call != NULL) {
 208                         refcount_set(&call->a_count, 1);
 209                         locks_init_lock(&call->a_args.lock.fl);
 210                         locks_init_lock(&call->a_res.lock.fl);
 211                         call->a_host = nlm_get_host(host);
 212                         return call;
 213                 }
 214                 if (signalled())
 215                         break;
 216                 printk("nlm_alloc_call: failed, waiting for memory\n");
 217                 schedule_timeout_interruptible(5*HZ);
 218         }
 219         return NULL;
 220 }
 221
 222 void nlmclnt_release_call(struct nlm_rqst *call)
 223 {
 224         const struct nlmclnt_operations *nlmclnt_ops = call->a_host->h_nlmclnt_ops;
 225
 226         if (!refcount_dec_and_test(&call->a_count))
 227                 return;
 228         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_release_call)
 229                 nlmclnt_ops->nlmclnt_release_call(call->a_callback_data);
 230         nlmclnt_release_host(call->a_host);
 231         nlmclnt_release_lockargs(call);
 232         kfree(call);
 233 }
 234
 235 static void nlmclnt_rpc_release(void *data)
 236 {
 237         nlmclnt_release_call(data);
 238 }
 239
 240 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 241 {
 242         DEFINE_WAIT(wait);
 243         int status = -EINTR;
 244
 245         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 246         if (!signalled ()) {
 247                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 248                 try_to_freeze();
 249                 if (!signalled ())
 250                         status = 0;
 251         }
 252         finish_wait(queue, &wait);
 253         return status;
 254 }
 255
 256 /*
 257  * Generic NLM call
 258  */
 259 static int
 260 nlmclnt_call(const struct cred *cred, struct nlm_rqst *req, u32 proc)
 261 {
 262         struct nlm_host *host = req->a_host;
 263         struct rpc_clnt *clnt;
 264         struct nlm_args *argp = &req->a_args;
 265         struct nlm_res  *resp = &req->a_res;
 266         struct rpc_message msg = {
 267                 .rpc_argp       = argp,
 268                 .rpc_resp       = resp,
 269                 .rpc_cred       = cred,
 270         };
 271         int             status;
 272
 273         dprintk("lockd: call procedure %d on %s\n",
 274                         (int)proc, host->h_name);
 275
 276         do {
 277                 if (host->h_reclaiming && !argp->reclaim)
 278                         goto in_grace_period;
 279
 280                 /* If we have no RPC client yet, create one. */
 281                 if ((clnt = nlm_bind_host(host)) == NULL)
 282                         return -ENOLCK;
 283                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 284
 285                 /* Perform the RPC call. If an error occurs, try again */
 286                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 287                         dprintk("lockd: rpc_call returned error %d\n", -status);
 288                         switch (status) {
 289                         case -EPROTONOSUPPORT:
 290                                 status = -EINVAL;
 291                                 break;
 292                         case -ECONNREFUSED:
 293                         case -ETIMEDOUT:
 294                         case -ENOTCONN:
 295                                 nlm_rebind_host(host);
 296                                 status = -EAGAIN;
 297                                 break;
 298                         case -ERESTARTSYS:
 299                                 return signalled () ? -EINTR : status;
 300                         default:
 301                                 break;
 302                         }
 303                         break;
 304                 } else
 305                 if (resp->status == nlm_lck_denied_grace_period) {
 306                         dprintk("lockd: server in grace period\n");
 307                         if (argp->reclaim) {
 308                                 printk(KERN_WARNING
 309                                      "lockd: spurious grace period reject?!\n");
 310                                 return -ENOLCK;
 311                         }
 312                 } else {
 313                         if (!argp->reclaim) {
 314                                 /* We appear to be out of the grace period */
 315                                 wake_up_all(&host->h_gracewait);
 316                         }
 317                         dprintk("lockd: server returns status %d\n",
 318                                 ntohl(resp->status));
 319                         return 0;       /* Okay, call complete */
 320                 }
 321
 322 in_grace_period:
 323                 /*
 324                  * The server has rebooted and appears to be in the grace
 325                  * period during which locks are only allowed to be
 326                  * reclaimed.
 327                  * We can only back off and try again later.
 328                  */
 329                 status = nlm_wait_on_grace(&host->h_gracewait);
 330         } while (status == 0);
 331
 332         return status;
 333 }
 334
 335 /*
 336  * Generic NLM call, async version.
 337  */
 338 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 339 {
 340         struct nlm_host *host = req->a_host;
 341         struct rpc_clnt *clnt;
 342         struct rpc_task_setup task_setup_data = {
 343                 .rpc_message = msg,
 344                 .callback_ops = tk_ops,
 345                 .callback_data = req,
 346                 .flags = RPC_TASK_ASYNC,
 347         };
 348
 349         dprintk("lockd: call procedure %d on %s (async)\n",
 350                         (int)proc, host->h_name);
 351
 352         /* If we have no RPC client yet, create one. */
 353         clnt = nlm_bind_host(host);
 354         if (clnt == NULL)
 355                 goto out_err;
 356         msg->rpc_proc = &clnt->cl_procinfo[proc];
 357         task_setup_data.rpc_client = clnt;
 358
 359         /* bootstrap and kick off the async RPC call */
 360         return rpc_run_task(&task_setup_data);
 361 out_err:
 362         tk_ops->rpc_release(req);
 363         return ERR_PTR(-ENOLCK);
 364 }
 365
 366 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 367 {
 368         struct rpc_task *task;
 369
 370         task = __nlm_async_call(req, proc, msg, tk_ops);
 371         if (IS_ERR(task))
 372                 return PTR_ERR(task);
 373         rpc_put_task(task);
 374         return 0;
 375 }
 376
 377 /*
 378  * NLM asynchronous call.
 379  */
 380 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 381 {
 382         struct rpc_message msg = {
 383                 .rpc_argp       = &req->a_args,
 384                 .rpc_resp       = &req->a_res,
 385         };
 386         return nlm_do_async_call(req, proc, &msg, tk_ops);
 387 }
 388
 389 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 390 {
 391         struct rpc_message msg = {
 392                 .rpc_argp       = &req->a_res,
 393         };
 394         return nlm_do_async_call(req, proc, &msg, tk_ops);
 395 }
 396
 397 /*
 398  * NLM client asynchronous call.
 399  *
 400  * Note that although the calls are asynchronous, and are therefore
 401  *      guaranteed to complete, we still always attempt to wait for
 402  *      completion in order to be able to correctly track the lock
 403  *      state.
 404  */
 405 static int nlmclnt_async_call(const struct cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 406 {
 407         struct rpc_message msg = {
 408                 .rpc_argp       = &req->a_args,
 409                 .rpc_resp       = &req->a_res,
 410                 .rpc_cred       = cred,
 411         };
 412         struct rpc_task *task;
 413         int err;
 414
 415         task = __nlm_async_call(req, proc, &msg, tk_ops);
 416         if (IS_ERR(task))
 417                 return PTR_ERR(task);
 418         err = rpc_wait_for_completion_task(task);
 419         rpc_put_task(task);
 420         return err;
 421 }
 422
 423 /*
 424  * TEST for the presence of a conflicting lock
 425  */
 426 static int
 427 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 428 {
 429         int     status;
 430
 431         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 432         if (status < 0)
 433                 goto out;
 434
 435         switch (req->a_res.status) {
 436                 case nlm_granted:
 437                         fl->fl_type = F_UNLCK;
 438                         break;
 439                 case nlm_lck_denied:
 440                         /*
 441                          * Report the conflicting lock back to the application.
 442                          */
 443                         fl->fl_start = req->a_res.lock.fl.fl_start;
 444                         fl->fl_end = req->a_res.lock.fl.fl_end;
 445                         fl->fl_type = req->a_res.lock.fl.fl_type;
 446                         fl->fl_pid = -req->a_res.lock.fl.fl_pid;
 447                         break;
 448                 default:
 449                         status = nlm_stat_to_errno(req->a_res.status);
 450         }
 451 out:
 452         nlmclnt_release_call(req);
 453         return status;
 454 }
 455
 456 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 457 {
 458         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 459         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 460         new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
 461         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 462         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 463 }
 464
 465 static void nlmclnt_locks_release_private(struct file_lock *fl)
 466 {
 467         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 468         list_del(&fl->fl_u.nfs_fl.list);
 469         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 470         nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 471 }
 472
 473 static const struct file_lock_operations nlmclnt_lock_ops = {
 474         .fl_copy_lock = nlmclnt_locks_copy_lock,
 475         .fl_release_private = nlmclnt_locks_release_private,
 476 };
 477
 478 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 479 {
 480         fl->fl_u.nfs_fl.state = 0;
 481         fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 482         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 483         fl->fl_ops = &nlmclnt_lock_ops;
 484 }
 485
 486 static int do_vfs_lock(struct file_lock *fl)
 487 {
 488         return locks_lock_file_wait(fl->fl_file, fl);
 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         const struct 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         nlmclnt_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                 struct nlm_rqst *req)
 621 {
 622         int             status;
 623
 624         memset(req, 0, sizeof(*req));
 625         locks_init_lock(&req->a_args.lock.fl);
 626         locks_init_lock(&req->a_res.lock.fl);
 627         req->a_host  = host;
 628
 629         /* Set up the argument struct */
 630         nlmclnt_setlockargs(req, fl);
 631         req->a_args.reclaim = 1;
 632
 633         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 634         if (status >= 0 && req->a_res.status == nlm_granted)
 635                 return 0;
 636
 637         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 638                                 "(errno %d, status %d)\n", fl->fl_pid,
 639                                 status, ntohl(req->a_res.status));
 640
 641         /*
 642          * FIXME: This is a serious failure. We can
 643          *
 644          *  a.  Ignore the problem
 645          *  b.  Send the owning process some signal (Linux doesn't have
 646          *      SIGLOST, though...)
 647          *  c.  Retry the operation
 648          *
 649          * Until someone comes up with a simple implementation
 650          * for b or c, I'll choose option a.
 651          */
 652
 653         return -ENOLCK;
 654 }
 655
 656 /*
 657  * UNLOCK: remove an existing lock
 658  */
 659 static int
 660 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 661 {
 662         struct nlm_host *host = req->a_host;
 663         struct nlm_res  *resp = &req->a_res;
 664         int status;
 665         unsigned char fl_flags = fl->fl_flags;
 666
 667         /*
 668          * Note: the server is supposed to either grant us the unlock
 669          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 670          * case, we want to unlock.
 671          */
 672         fl->fl_flags |= FL_EXISTS;
 673         down_read(&host->h_rwsem);
 674         status = do_vfs_lock(fl);
 675         up_read(&host->h_rwsem);
 676         fl->fl_flags = fl_flags;
 677         if (status == -ENOENT) {
 678                 status = 0;
 679                 goto out;
 680         }
 681
 682         refcount_inc(&req->a_count);
 683         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 684                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 685         if (status < 0)
 686                 goto out;
 687
 688         if (resp->status == nlm_granted)
 689                 goto out;
 690
 691         if (resp->status != nlm_lck_denied_nolocks)
 692                 printk("lockd: unexpected unlock status: %d\n",
 693                         ntohl(resp->status));
 694         /* What to do now? I'm out of my depth... */
 695         status = -ENOLCK;
 696 out:
 697         nlmclnt_release_call(req);
 698         return status;
 699 }
 700
 701 static void nlmclnt_unlock_prepare(struct rpc_task *task, void *data)
 702 {
 703         struct nlm_rqst *req = data;
 704         const struct nlmclnt_operations *nlmclnt_ops = req->a_host->h_nlmclnt_ops;
 705         bool defer_call = false;
 706
 707         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_unlock_prepare)
 708                 defer_call = nlmclnt_ops->nlmclnt_unlock_prepare(task, req->a_callback_data);
 709
 710         if (!defer_call)
 711                 rpc_call_start(task);
 712 }
 713
 714 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 715 {
 716         struct nlm_rqst *req = data;
 717         u32 status = ntohl(req->a_res.status);
 718
 719         if (RPC_SIGNALLED(task))
 720                 goto die;
 721
 722         if (task->tk_status < 0) {
 723                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 724                 switch (task->tk_status) {
 725                 case -EACCES:
 726                 case -EIO:
 727                         goto die;
 728                 default:
 729                         goto retry_rebind;
 730                 }
 731         }
 732         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 733                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 734                 goto retry_unlock;
 735         }
 736         if (status != NLM_LCK_GRANTED)
 737                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 738 die:
 739         return;
 740  retry_rebind:
 741         nlm_rebind_host(req->a_host);
 742  retry_unlock:
 743         rpc_restart_call(task);
 744 }
 745
 746 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 747         .rpc_call_prepare = nlmclnt_unlock_prepare,
 748         .rpc_call_done = nlmclnt_unlock_callback,
 749         .rpc_release = nlmclnt_rpc_release,
 750 };
 751
 752 /*
 753  * Cancel a blocked lock request.
 754  * We always use an async RPC call for this in order not to hang a
 755  * process that has been Ctrl-C'ed.
 756  */
 757 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 758 {
 759         struct nlm_rqst *req;
 760         int status;
 761
 762         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 763                 "       Attempting to cancel lock.\n");
 764
 765         req = nlm_alloc_call(host);
 766         if (!req)
 767                 return -ENOMEM;
 768         req->a_flags = RPC_TASK_ASYNC;
 769
 770         nlmclnt_setlockargs(req, fl);
 771         req->a_args.block = block;
 772
 773         refcount_inc(&req->a_count);
 774         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 775                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 776         if (status == 0 && req->a_res.status == nlm_lck_denied)
 777                 status = -ENOLCK;
 778         nlmclnt_release_call(req);
 779         return status;
 780 }
 781
 782 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 783 {
 784         struct nlm_rqst *req = data;
 785         u32 status = ntohl(req->a_res.status);
 786
 787         if (RPC_SIGNALLED(task))
 788                 goto die;
 789
 790         if (task->tk_status < 0) {
 791                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 792                                         task->tk_status);
 793                 goto retry_cancel;
 794         }
 795
 796         dprintk("lockd: cancel status %u (task %u)\n",
 797                         status, task->tk_pid);
 798
 799         switch (status) {
 800         case NLM_LCK_GRANTED:
 801         case NLM_LCK_DENIED_GRACE_PERIOD:
 802         case NLM_LCK_DENIED:
 803                 /* Everything's good */
 804                 break;
 805         case NLM_LCK_DENIED_NOLOCKS:
 806                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 807                 goto retry_cancel;
 808         default:
 809                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 810                         status);
 811         }
 812
 813 die:
 814         return;
 815
 816 retry_cancel:
 817         /* Don't ever retry more than 3 times */
 818         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 819                 goto die;
 820         nlm_rebind_host(req->a_host);
 821         rpc_restart_call(task);
 822         rpc_delay(task, 30 * HZ);
 823 }
 824
 825 static const struct rpc_call_ops nlmclnt_cancel_ops = {
 826         .rpc_call_done = nlmclnt_cancel_callback,
 827         .rpc_release = nlmclnt_rpc_release,
 828 };
 829
 830 /*
 831  * Convert an NLM status code to a generic kernel errno
 832  */
 833 static int
 834 nlm_stat_to_errno(__be32 status)
 835 {
 836         switch(ntohl(status)) {
 837         case NLM_LCK_GRANTED:
 838                 return 0;
 839         case NLM_LCK_DENIED:
 840                 return -EAGAIN;
 841         case NLM_LCK_DENIED_NOLOCKS:
 842         case NLM_LCK_DENIED_GRACE_PERIOD:
 843                 return -ENOLCK;
 844         case NLM_LCK_BLOCKED:
 845                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 846                 return -ENOLCK;
 847 #ifdef CONFIG_LOCKD_V4
 848         case NLM_DEADLCK:
 849                 return -EDEADLK;
 850         case NLM_ROFS:
 851                 return -EROFS;
 852         case NLM_STALE_FH:
 853                 return -ESTALE;
 854         case NLM_FBIG:
 855                 return -EOVERFLOW;
 856         case NLM_FAILED:
 857                 return -ENOLCK;
 858 #endif
 859         }
 860         printk(KERN_NOTICE "lockd: unexpected server status %d\n",
 861                  ntohl(status));
 862         return -ENOLCK;
 863 }