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/filelock.h>
  16 #include <linux/nfs_fs.h>
  17 #include <linux/utsname.h>
  18 #include <linux/freezer.h>
  19 #include <linux/sunrpc/clnt.h>
  20 #include <linux/sunrpc/svc.h>
  21 #include <linux/lockd/lockd.h>
  22
  23 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  24 #define NLMCLNT_GRACE_WAIT      (5*HZ)
  25 #define NLMCLNT_POLL_TIMEOUT    (30*HZ)
  26 #define NLMCLNT_MAX_RETRIES     3
  27
  28 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
  29 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
  30 static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
  31 static int      nlm_stat_to_errno(__be32 stat);
  32 static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
  33 static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
  34
  35 static const struct rpc_call_ops nlmclnt_unlock_ops;
  36 static const struct rpc_call_ops nlmclnt_cancel_ops;
  37
  38 /*
  39  * Cookie counter for NLM requests
  40  */
  41 static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
  42
  43 void nlmclnt_next_cookie(struct nlm_cookie *c)
  44 {
  45         u32     cookie = atomic_inc_return(&nlm_cookie);
  46
  47         memcpy(c->data, &cookie, 4);
  48         c->len=4;
  49 }
  50
  51 static struct nlm_lockowner *
  52 nlmclnt_get_lockowner(struct nlm_lockowner *lockowner)
  53 {
  54         refcount_inc(&lockowner->count);
  55         return lockowner;
  56 }
  57
  58 static void nlmclnt_put_lockowner(struct nlm_lockowner *lockowner)
  59 {
  60         if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
  61                 return;
  62         list_del(&lockowner->list);
  63         spin_unlock(&lockowner->host->h_lock);
  64         nlmclnt_release_host(lockowner->host);
  65         kfree(lockowner);
  66 }
  67
  68 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
  69 {
  70         struct nlm_lockowner *lockowner;
  71         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  72                 if (lockowner->pid == pid)
  73                         return -EBUSY;
  74         }
  75         return 0;
  76 }
  77
  78 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
  79 {
  80         uint32_t res;
  81         do {
  82                 res = host->h_pidcount++;
  83         } while (nlm_pidbusy(host, res) < 0);
  84         return res;
  85 }
  86
  87 static struct nlm_lockowner *__nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  88 {
  89         struct nlm_lockowner *lockowner;
  90         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  91                 if (lockowner->owner != owner)
  92                         continue;
  93                 return nlmclnt_get_lockowner(lockowner);
  94         }
  95         return NULL;
  96 }
  97
  98 static struct nlm_lockowner *nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  99 {
 100         struct nlm_lockowner *res, *new = NULL;
 101
 102         spin_lock(&host->h_lock);
 103         res = __nlmclnt_find_lockowner(host, owner);
 104         if (res == NULL) {
 105                 spin_unlock(&host->h_lock);
 106                 new = kmalloc(sizeof(*new), GFP_KERNEL);
 107                 spin_lock(&host->h_lock);
 108                 res = __nlmclnt_find_lockowner(host, owner);
 109                 if (res == NULL && new != NULL) {
 110                         res = new;
 111                         refcount_set(&new->count, 1);
 112                         new->owner = owner;
 113                         new->pid = __nlm_alloc_pid(host);
 114                         new->host = nlm_get_host(host);
 115                         list_add(&new->list, &host->h_lockowners);
 116                         new = NULL;
 117                 }
 118         }
 119         spin_unlock(&host->h_lock);
 120         kfree(new);
 121         return res;
 122 }
 123
 124 /*
 125  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 126  */
 127 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 128 {
 129         struct nlm_args *argp = &req->a_args;
 130         struct nlm_lock *lock = &argp->lock;
 131         char *nodename = req->a_host->h_rpcclnt->cl_nodename;
 132
 133         nlmclnt_next_cookie(&argp->cookie);
 134         memcpy(&lock->fh, NFS_FH(locks_inode(fl->fl_file)), sizeof(struct nfs_fh));
 135         lock->caller  = nodename;
 136         lock->oh.data = req->a_owner;
 137         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
 138                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
 139                                 nodename);
 140         lock->svid = fl->fl_u.nfs_fl.owner->pid;
 141         lock->fl.fl_start = fl->fl_start;
 142         lock->fl.fl_end = fl->fl_end;
 143         lock->fl.fl_type = fl->fl_type;
 144 }
 145
 146 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
 147 {
 148         WARN_ON_ONCE(req->a_args.lock.fl.fl_ops != NULL);
 149 }
 150
 151 /**
 152  * nlmclnt_proc - Perform a single client-side lock request
 153  * @host: address of a valid nlm_host context representing the NLM server
 154  * @cmd: fcntl-style file lock operation to perform
 155  * @fl: address of arguments for the lock operation
 156  * @data: address of data to be sent to callback operations
 157  *
 158  */
 159 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data)
 160 {
 161         struct nlm_rqst         *call;
 162         int                     status;
 163         const struct nlmclnt_operations *nlmclnt_ops = host->h_nlmclnt_ops;
 164
 165         call = nlm_alloc_call(host);
 166         if (call == NULL)
 167                 return -ENOMEM;
 168
 169         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_alloc_call)
 170                 nlmclnt_ops->nlmclnt_alloc_call(data);
 171
 172         nlmclnt_locks_init_private(fl, host);
 173         if (!fl->fl_u.nfs_fl.owner) {
 174                 /* lockowner allocation has failed */
 175                 nlmclnt_release_call(call);
 176                 return -ENOMEM;
 177         }
 178         /* Set up the argument struct */
 179         nlmclnt_setlockargs(call, fl);
 180         call->a_callback_data = data;
 181
 182         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 183                 if (fl->fl_type != F_UNLCK) {
 184                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 185                         status = nlmclnt_lock(call, fl);
 186                 } else
 187                         status = nlmclnt_unlock(call, fl);
 188         } else if (IS_GETLK(cmd))
 189                 status = nlmclnt_test(call, fl);
 190         else
 191                 status = -EINVAL;
 192         fl->fl_ops->fl_release_private(fl);
 193         fl->fl_ops = NULL;
 194
 195         dprintk("lockd: clnt proc returns %d\n", status);
 196         return status;
 197 }
 198 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 199
 200 /*
 201  * Allocate an NLM RPC call struct
 202  */
 203 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 204 {
 205         struct nlm_rqst *call;
 206
 207         for(;;) {
 208                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 209                 if (call != NULL) {
 210                         refcount_set(&call->a_count, 1);
 211                         locks_init_lock(&call->a_args.lock.fl);
 212                         locks_init_lock(&call->a_res.lock.fl);
 213                         call->a_host = nlm_get_host(host);
 214                         return call;
 215                 }
 216                 if (signalled())
 217                         break;
 218                 printk("nlm_alloc_call: failed, waiting for memory\n");
 219                 schedule_timeout_interruptible(5*HZ);
 220         }
 221         return NULL;
 222 }
 223
 224 void nlmclnt_release_call(struct nlm_rqst *call)
 225 {
 226         const struct nlmclnt_operations *nlmclnt_ops = call->a_host->h_nlmclnt_ops;
 227
 228         if (!refcount_dec_and_test(&call->a_count))
 229                 return;
 230         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_release_call)
 231                 nlmclnt_ops->nlmclnt_release_call(call->a_callback_data);
 232         nlmclnt_release_host(call->a_host);
 233         nlmclnt_release_lockargs(call);
 234         kfree(call);
 235 }
 236
 237 static void nlmclnt_rpc_release(void *data)
 238 {
 239         nlmclnt_release_call(data);
 240 }
 241
 242 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 243 {
 244         DEFINE_WAIT(wait);
 245         int status = -EINTR;
 246
 247         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 248         if (!signalled ()) {
 249                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 250                 try_to_freeze();
 251                 if (!signalled ())
 252                         status = 0;
 253         }
 254         finish_wait(queue, &wait);
 255         return status;
 256 }
 257
 258 /*
 259  * Generic NLM call
 260  */
 261 static int
 262 nlmclnt_call(const struct cred *cred, struct nlm_rqst *req, u32 proc)
 263 {
 264         struct nlm_host *host = req->a_host;
 265         struct rpc_clnt *clnt;
 266         struct nlm_args *argp = &req->a_args;
 267         struct nlm_res  *resp = &req->a_res;
 268         struct rpc_message msg = {
 269                 .rpc_argp       = argp,
 270                 .rpc_resp       = resp,
 271                 .rpc_cred       = cred,
 272         };
 273         int             status;
 274
 275         dprintk("lockd: call procedure %d on %s\n",
 276                         (int)proc, host->h_name);
 277
 278         do {
 279                 if (host->h_reclaiming && !argp->reclaim)
 280                         goto in_grace_period;
 281
 282                 /* If we have no RPC client yet, create one. */
 283                 if ((clnt = nlm_bind_host(host)) == NULL)
 284                         return -ENOLCK;
 285                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 286
 287                 /* Perform the RPC call. If an error occurs, try again */
 288                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 289                         dprintk("lockd: rpc_call returned error %d\n", -status);
 290                         switch (status) {
 291                         case -EPROTONOSUPPORT:
 292                                 status = -EINVAL;
 293                                 break;
 294                         case -ECONNREFUSED:
 295                         case -ETIMEDOUT:
 296                         case -ENOTCONN:
 297                                 nlm_rebind_host(host);
 298                                 status = -EAGAIN;
 299                                 break;
 300                         case -ERESTARTSYS:
 301                                 return signalled () ? -EINTR : status;
 302                         default:
 303                                 break;
 304                         }
 305                         break;
 306                 } else
 307                 if (resp->status == nlm_lck_denied_grace_period) {
 308                         dprintk("lockd: server in grace period\n");
 309                         if (argp->reclaim) {
 310                                 printk(KERN_WARNING
 311                                      "lockd: spurious grace period reject?!\n");
 312                                 return -ENOLCK;
 313                         }
 314                 } else {
 315                         if (!argp->reclaim) {
 316                                 /* We appear to be out of the grace period */
 317                                 wake_up_all(&host->h_gracewait);
 318                         }
 319                         dprintk("lockd: server returns status %d\n",
 320                                 ntohl(resp->status));
 321                         return 0;       /* Okay, call complete */
 322                 }
 323
 324 in_grace_period:
 325                 /*
 326                  * The server has rebooted and appears to be in the grace
 327                  * period during which locks are only allowed to be
 328                  * reclaimed.
 329                  * We can only back off and try again later.
 330                  */
 331                 status = nlm_wait_on_grace(&host->h_gracewait);
 332         } while (status == 0);
 333
 334         return status;
 335 }
 336
 337 /*
 338  * Generic NLM call, async version.
 339  */
 340 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 341 {
 342         struct nlm_host *host = req->a_host;
 343         struct rpc_clnt *clnt;
 344         struct rpc_task_setup task_setup_data = {
 345                 .rpc_message = msg,
 346                 .callback_ops = tk_ops,
 347                 .callback_data = req,
 348                 .flags = RPC_TASK_ASYNC,
 349         };
 350
 351         dprintk("lockd: call procedure %d on %s (async)\n",
 352                         (int)proc, host->h_name);
 353
 354         /* If we have no RPC client yet, create one. */
 355         clnt = nlm_bind_host(host);
 356         if (clnt == NULL)
 357                 goto out_err;
 358         msg->rpc_proc = &clnt->cl_procinfo[proc];
 359         task_setup_data.rpc_client = clnt;
 360
 361         /* bootstrap and kick off the async RPC call */
 362         return rpc_run_task(&task_setup_data);
 363 out_err:
 364         tk_ops->rpc_release(req);
 365         return ERR_PTR(-ENOLCK);
 366 }
 367
 368 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 369 {
 370         struct rpc_task *task;
 371
 372         task = __nlm_async_call(req, proc, msg, tk_ops);
 373         if (IS_ERR(task))
 374                 return PTR_ERR(task);
 375         rpc_put_task(task);
 376         return 0;
 377 }
 378
 379 /*
 380  * NLM asynchronous call.
 381  */
 382 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 383 {
 384         struct rpc_message msg = {
 385                 .rpc_argp       = &req->a_args,
 386                 .rpc_resp       = &req->a_res,
 387         };
 388         return nlm_do_async_call(req, proc, &msg, tk_ops);
 389 }
 390
 391 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 392 {
 393         struct rpc_message msg = {
 394                 .rpc_argp       = &req->a_res,
 395         };
 396         return nlm_do_async_call(req, proc, &msg, tk_ops);
 397 }
 398
 399 /*
 400  * NLM client asynchronous call.
 401  *
 402  * Note that although the calls are asynchronous, and are therefore
 403  *      guaranteed to complete, we still always attempt to wait for
 404  *      completion in order to be able to correctly track the lock
 405  *      state.
 406  */
 407 static int nlmclnt_async_call(const struct cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 408 {
 409         struct rpc_message msg = {
 410                 .rpc_argp       = &req->a_args,
 411                 .rpc_resp       = &req->a_res,
 412                 .rpc_cred       = cred,
 413         };
 414         struct rpc_task *task;
 415         int err;
 416
 417         task = __nlm_async_call(req, proc, &msg, tk_ops);
 418         if (IS_ERR(task))
 419                 return PTR_ERR(task);
 420         err = rpc_wait_for_completion_task(task);
 421         rpc_put_task(task);
 422         return err;
 423 }
 424
 425 /*
 426  * TEST for the presence of a conflicting lock
 427  */
 428 static int
 429 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 430 {
 431         int     status;
 432
 433         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 434         if (status < 0)
 435                 goto out;
 436
 437         switch (req->a_res.status) {
 438                 case nlm_granted:
 439                         fl->fl_type = F_UNLCK;
 440                         break;
 441                 case nlm_lck_denied:
 442                         /*
 443                          * Report the conflicting lock back to the application.
 444                          */
 445                         fl->fl_start = req->a_res.lock.fl.fl_start;
 446                         fl->fl_end = req->a_res.lock.fl.fl_end;
 447                         fl->fl_type = req->a_res.lock.fl.fl_type;
 448                         fl->fl_pid = -req->a_res.lock.fl.fl_pid;
 449                         break;
 450                 default:
 451                         status = nlm_stat_to_errno(req->a_res.status);
 452         }
 453 out:
 454         nlmclnt_release_call(req);
 455         return status;
 456 }
 457
 458 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 459 {
 460         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 461         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 462         new->fl_u.nfs_fl.owner = nlmclnt_get_lockowner(fl->fl_u.nfs_fl.owner);
 463         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 464         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 465 }
 466
 467 static void nlmclnt_locks_release_private(struct file_lock *fl)
 468 {
 469         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 470         list_del(&fl->fl_u.nfs_fl.list);
 471         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 472         nlmclnt_put_lockowner(fl->fl_u.nfs_fl.owner);
 473 }
 474
 475 static const struct file_lock_operations nlmclnt_lock_ops = {
 476         .fl_copy_lock = nlmclnt_locks_copy_lock,
 477         .fl_release_private = nlmclnt_locks_release_private,
 478 };
 479
 480 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 481 {
 482         fl->fl_u.nfs_fl.state = 0;
 483         fl->fl_u.nfs_fl.owner = nlmclnt_find_lockowner(host, fl->fl_owner);
 484         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 485         fl->fl_ops = &nlmclnt_lock_ops;
 486 }
 487
 488 static int do_vfs_lock(struct file_lock *fl)
 489 {
 490         return locks_lock_file_wait(fl->fl_file, fl);
 491 }
 492
 493 /*
 494  * LOCK: Try to create a lock
 495  *
 496  *                      Programmer Harassment Alert
 497  *
 498  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 499  * will faithfully return LCK_BLOCKED but never cares to notify us when
 500  * the lock could be granted. This way, our local process could hang
 501  * around forever waiting for the callback.
 502  *
 503  *  Solution A: Implement busy-waiting
 504  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 505  *
 506  * For now I am implementing solution A, because I hate the idea of
 507  * re-implementing lockd for a third time in two months. The async
 508  * calls shouldn't be too hard to do, however.
 509  *
 510  * This is one of the lovely things about standards in the NFS area:
 511  * they're so soft and squishy you can't really blame HP for doing this.
 512  */
 513 static int
 514 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 515 {
 516         const struct cred *cred = nfs_file_cred(fl->fl_file);
 517         struct nlm_host *host = req->a_host;
 518         struct nlm_res  *resp = &req->a_res;
 519         struct nlm_wait *block = NULL;
 520         unsigned char fl_flags = fl->fl_flags;
 521         unsigned char fl_type;
 522         int status = -ENOLCK;
 523
 524         if (nsm_monitor(host) < 0)
 525                 goto out;
 526         req->a_args.state = nsm_local_state;
 527
 528         fl->fl_flags |= FL_ACCESS;
 529         status = do_vfs_lock(fl);
 530         fl->fl_flags = fl_flags;
 531         if (status < 0)
 532                 goto out;
 533
 534         block = nlmclnt_prepare_block(host, fl);
 535 again:
 536         /*
 537          * Initialise resp->status to a valid non-zero value,
 538          * since 0 == nlm_lck_granted
 539          */
 540         resp->status = nlm_lck_blocked;
 541         for(;;) {
 542                 /* Reboot protection */
 543                 fl->fl_u.nfs_fl.state = host->h_state;
 544                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 545                 if (status < 0)
 546                         break;
 547                 /* Did a reclaimer thread notify us of a server reboot? */
 548                 if (resp->status ==  nlm_lck_denied_grace_period)
 549                         continue;
 550                 if (resp->status != nlm_lck_blocked)
 551                         break;
 552                 /* Wait on an NLM blocking lock */
 553                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 554                 if (status < 0)
 555                         break;
 556                 if (resp->status != nlm_lck_blocked)
 557                         break;
 558         }
 559
 560         /* if we were interrupted while blocking, then cancel the lock request
 561          * and exit
 562          */
 563         if (resp->status == nlm_lck_blocked) {
 564                 if (!req->a_args.block)
 565                         goto out_unlock;
 566                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 567                         goto out_unblock;
 568         }
 569
 570         if (resp->status == nlm_granted) {
 571                 down_read(&host->h_rwsem);
 572                 /* Check whether or not the server has rebooted */
 573                 if (fl->fl_u.nfs_fl.state != host->h_state) {
 574                         up_read(&host->h_rwsem);
 575                         goto again;
 576                 }
 577                 /* Ensure the resulting lock will get added to granted list */
 578                 fl->fl_flags |= FL_SLEEP;
 579                 if (do_vfs_lock(fl) < 0)
 580                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 581                 up_read(&host->h_rwsem);
 582                 fl->fl_flags = fl_flags;
 583                 status = 0;
 584         }
 585         if (status < 0)
 586                 goto out_unlock;
 587         /*
 588          * EAGAIN doesn't make sense for sleeping locks, and in some
 589          * cases NLM_LCK_DENIED is returned for a permanent error.  So
 590          * turn it into an ENOLCK.
 591          */
 592         if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
 593                 status = -ENOLCK;
 594         else
 595                 status = nlm_stat_to_errno(resp->status);
 596 out_unblock:
 597         nlmclnt_finish_block(block);
 598 out:
 599         nlmclnt_release_call(req);
 600         return status;
 601 out_unlock:
 602         /* Fatal error: ensure that we remove the lock altogether */
 603         dprintk("lockd: lock attempt ended in fatal error.\n"
 604                 "       Attempting to unlock.\n");
 605         nlmclnt_finish_block(block);
 606         fl_type = fl->fl_type;
 607         fl->fl_type = F_UNLCK;
 608         down_read(&host->h_rwsem);
 609         do_vfs_lock(fl);
 610         up_read(&host->h_rwsem);
 611         fl->fl_type = fl_type;
 612         fl->fl_flags = fl_flags;
 613         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 614         return status;
 615 }
 616
 617 /*
 618  * RECLAIM: Try to reclaim a lock
 619  */
 620 int
 621 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
 622                 struct nlm_rqst *req)
 623 {
 624         int             status;
 625
 626         memset(req, 0, sizeof(*req));
 627         locks_init_lock(&req->a_args.lock.fl);
 628         locks_init_lock(&req->a_res.lock.fl);
 629         req->a_host  = host;
 630
 631         /* Set up the argument struct */
 632         nlmclnt_setlockargs(req, fl);
 633         req->a_args.reclaim = 1;
 634
 635         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 636         if (status >= 0 && req->a_res.status == nlm_granted)
 637                 return 0;
 638
 639         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 640                                 "(errno %d, status %d)\n", fl->fl_pid,
 641                                 status, ntohl(req->a_res.status));
 642
 643         /*
 644          * FIXME: This is a serious failure. We can
 645          *
 646          *  a.  Ignore the problem
 647          *  b.  Send the owning process some signal (Linux doesn't have
 648          *      SIGLOST, though...)
 649          *  c.  Retry the operation
 650          *
 651          * Until someone comes up with a simple implementation
 652          * for b or c, I'll choose option a.
 653          */
 654
 655         return -ENOLCK;
 656 }
 657
 658 /*
 659  * UNLOCK: remove an existing lock
 660  */
 661 static int
 662 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 663 {
 664         struct nlm_host *host = req->a_host;
 665         struct nlm_res  *resp = &req->a_res;
 666         int status;
 667         unsigned char fl_flags = fl->fl_flags;
 668
 669         /*
 670          * Note: the server is supposed to either grant us the unlock
 671          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 672          * case, we want to unlock.
 673          */
 674         fl->fl_flags |= FL_EXISTS;
 675         down_read(&host->h_rwsem);
 676         status = do_vfs_lock(fl);
 677         up_read(&host->h_rwsem);
 678         fl->fl_flags = fl_flags;
 679         if (status == -ENOENT) {
 680                 status = 0;
 681                 goto out;
 682         }
 683
 684         refcount_inc(&req->a_count);
 685         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 686                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 687         if (status < 0)
 688                 goto out;
 689
 690         if (resp->status == nlm_granted)
 691                 goto out;
 692
 693         if (resp->status != nlm_lck_denied_nolocks)
 694                 printk("lockd: unexpected unlock status: %d\n",
 695                         ntohl(resp->status));
 696         /* What to do now? I'm out of my depth... */
 697         status = -ENOLCK;
 698 out:
 699         nlmclnt_release_call(req);
 700         return status;
 701 }
 702
 703 static void nlmclnt_unlock_prepare(struct rpc_task *task, void *data)
 704 {
 705         struct nlm_rqst *req = data;
 706         const struct nlmclnt_operations *nlmclnt_ops = req->a_host->h_nlmclnt_ops;
 707         bool defer_call = false;
 708
 709         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_unlock_prepare)
 710                 defer_call = nlmclnt_ops->nlmclnt_unlock_prepare(task, req->a_callback_data);
 711
 712         if (!defer_call)
 713                 rpc_call_start(task);
 714 }
 715
 716 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 717 {
 718         struct nlm_rqst *req = data;
 719         u32 status = ntohl(req->a_res.status);
 720
 721         if (RPC_SIGNALLED(task))
 722                 goto die;
 723
 724         if (task->tk_status < 0) {
 725                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 726                 switch (task->tk_status) {
 727                 case -EACCES:
 728                 case -EIO:
 729                         goto die;
 730                 default:
 731                         goto retry_rebind;
 732                 }
 733         }
 734         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 735                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 736                 goto retry_unlock;
 737         }
 738         if (status != NLM_LCK_GRANTED)
 739                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 740 die:
 741         return;
 742  retry_rebind:
 743         nlm_rebind_host(req->a_host);
 744  retry_unlock:
 745         rpc_restart_call(task);
 746 }
 747
 748 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 749         .rpc_call_prepare = nlmclnt_unlock_prepare,
 750         .rpc_call_done = nlmclnt_unlock_callback,
 751         .rpc_release = nlmclnt_rpc_release,
 752 };
 753
 754 /*
 755  * Cancel a blocked lock request.
 756  * We always use an async RPC call for this in order not to hang a
 757  * process that has been Ctrl-C'ed.
 758  */
 759 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 760 {
 761         struct nlm_rqst *req;
 762         int status;
 763
 764         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 765                 "       Attempting to cancel lock.\n");
 766
 767         req = nlm_alloc_call(host);
 768         if (!req)
 769                 return -ENOMEM;
 770         req->a_flags = RPC_TASK_ASYNC;
 771
 772         nlmclnt_setlockargs(req, fl);
 773         req->a_args.block = block;
 774
 775         refcount_inc(&req->a_count);
 776         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 777                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 778         if (status == 0 && req->a_res.status == nlm_lck_denied)
 779                 status = -ENOLCK;
 780         nlmclnt_release_call(req);
 781         return status;
 782 }
 783
 784 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 785 {
 786         struct nlm_rqst *req = data;
 787         u32 status = ntohl(req->a_res.status);
 788
 789         if (RPC_SIGNALLED(task))
 790                 goto die;
 791
 792         if (task->tk_status < 0) {
 793                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 794                                         task->tk_status);
 795                 goto retry_cancel;
 796         }
 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 }