root/fs/lockd/clntproc.c

DEFINITIONS

1. nlmclnt_next_cookie
2. nlmclnt_get_lockowner
3. nlmclnt_put_lockowner
4. nlm_pidbusy
5. __nlm_alloc_pid
6. __nlmclnt_find_lockowner
7. nlmclnt_find_lockowner
8. nlmclnt_setlockargs
9. nlmclnt_release_lockargs
10. nlmclnt_proc
11. nlm_alloc_call
12. nlmclnt_release_call
13. nlmclnt_rpc_release
14. nlm_wait_on_grace
15. nlmclnt_call
16. __nlm_async_call
17. nlm_do_async_call
18. nlm_async_call
19. nlm_async_reply
20. nlmclnt_async_call
21. nlmclnt_test
22. nlmclnt_locks_copy_lock
23. nlmclnt_locks_release_private
24. nlmclnt_locks_init_private
25. do_vfs_lock
26. nlmclnt_lock
27. nlmclnt_reclaim
28. nlmclnt_unlock
29. nlmclnt_unlock_prepare
30. nlmclnt_unlock_callback
31. nlmclnt_cancel
32. nlmclnt_cancel_callback
33. nlm_stat_to_errno

   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 *
  51 nlmclnt_get_lockowner(struct nlm_lockowner *lockowner)
  52 {
  53         refcount_inc(&lockowner->count);
  54         return lockowner;
  55 }
  56 
  57 static void nlmclnt_put_lockowner(struct nlm_lockowner *lockowner)
  58 {
  59         if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
  60                 return;
  61         list_del(&lockowner->list);
  62         spin_unlock(&lockowner->host->h_lock);
  63         nlmclnt_release_host(lockowner->host);
  64         kfree(lockowner);
  65 }
  66 
  67 static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
  68 {
  69         struct nlm_lockowner *lockowner;
  70         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  71                 if (lockowner->pid == pid)
  72                         return -EBUSY;
  73         }
  74         return 0;
  75 }
  76 
  77 static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
  78 {
  79         uint32_t res;
  80         do {
  81                 res = host->h_pidcount++;
  82         } while (nlm_pidbusy(host, res) < 0);
  83         return res;
  84 }
  85 
  86 static struct nlm_lockowner *__nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  87 {
  88         struct nlm_lockowner *lockowner;
  89         list_for_each_entry(lockowner, &host->h_lockowners, list) {
  90                 if (lockowner->owner != owner)
  91                         continue;
  92                 return nlmclnt_get_lockowner(lockowner);
  93         }
  94         return NULL;
  95 }
  96 
  97 static struct nlm_lockowner *nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  98 {
  99         struct nlm_lockowner *res, *new = NULL;
 100 
 101         spin_lock(&host->h_lock);
 102         res = __nlmclnt_find_lockowner(host, owner);
 103         if (res == NULL) {
 104                 spin_unlock(&host->h_lock);
 105                 new = kmalloc(sizeof(*new), GFP_KERNEL);
 106                 spin_lock(&host->h_lock);
 107                 res = __nlmclnt_find_lockowner(host, owner);
 108                 if (res == NULL && new != NULL) {
 109                         res = new;
 110                         refcount_set(&new->count, 1);
 111                         new->owner = owner;
 112                         new->pid = __nlm_alloc_pid(host);
 113                         new->host = nlm_get_host(host);
 114                         list_add(&new->list, &host->h_lockowners);
 115                         new = NULL;
 116                 }
 117         }
 118         spin_unlock(&host->h_lock);
 119         kfree(new);
 120         return res;
 121 }
 122 
 123 /*
 124  * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 125  */
 126 static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 127 {
 128         struct nlm_args *argp = &req->a_args;
 129         struct nlm_lock *lock = &argp->lock;
 130         char *nodename = req->a_host->h_rpcclnt->cl_nodename;
 131 
 132         nlmclnt_next_cookie(&argp->cookie);
 133         memcpy(&lock->fh, NFS_FH(locks_inode(fl->fl_file)), sizeof(struct nfs_fh));
 134         lock->caller  = nodename;
 135         lock->oh.data = req->a_owner;
 136         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
 137                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
 138                                 nodename);
 139         lock->svid = fl->fl_u.nfs_fl.owner->pid;
 140         lock->fl.fl_start = fl->fl_start;
 141         lock->fl.fl_end = fl->fl_end;
 142         lock->fl.fl_type = fl->fl_type;
 143 }
 144 
 145 static void nlmclnt_release_lockargs(struct nlm_rqst *req)
 146 {
 147         WARN_ON_ONCE(req->a_args.lock.fl.fl_ops != NULL);
 148 }
 149 
 150 /**
 151  * nlmclnt_proc - Perform a single client-side lock request
 152  * @host: address of a valid nlm_host context representing the NLM server
 153  * @cmd: fcntl-style file lock operation to perform
 154  * @fl: address of arguments for the lock operation
 155  * @data: address of data to be sent to callback operations
 156  *
 157  */
 158 int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data)
 159 {
 160         struct nlm_rqst         *call;
 161         int                     status;
 162         const struct nlmclnt_operations *nlmclnt_ops = host->h_nlmclnt_ops;
 163 
 164         call = nlm_alloc_call(host);
 165         if (call == NULL)
 166                 return -ENOMEM;
 167 
 168         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_alloc_call)
 169                 nlmclnt_ops->nlmclnt_alloc_call(data);
 170 
 171         nlmclnt_locks_init_private(fl, host);
 172         if (!fl->fl_u.nfs_fl.owner) {
 173                 /* lockowner allocation has failed */
 174                 nlmclnt_release_call(call);
 175                 return -ENOMEM;
 176         }
 177         /* Set up the argument struct */
 178         nlmclnt_setlockargs(call, fl);
 179         call->a_callback_data = data;
 180 
 181         if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 182                 if (fl->fl_type != F_UNLCK) {
 183                         call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 184                         status = nlmclnt_lock(call, fl);
 185                 } else
 186                         status = nlmclnt_unlock(call, fl);
 187         } else if (IS_GETLK(cmd))
 188                 status = nlmclnt_test(call, fl);
 189         else
 190                 status = -EINVAL;
 191         fl->fl_ops->fl_release_private(fl);
 192         fl->fl_ops = NULL;
 193 
 194         dprintk("lockd: clnt proc returns %d\n", status);
 195         return status;
 196 }
 197 EXPORT_SYMBOL_GPL(nlmclnt_proc);
 198 
 199 /*
 200  * Allocate an NLM RPC call struct
 201  */
 202 struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 203 {
 204         struct nlm_rqst *call;
 205 
 206         for(;;) {
 207                 call = kzalloc(sizeof(*call), GFP_KERNEL);
 208                 if (call != NULL) {
 209                         refcount_set(&call->a_count, 1);
 210                         locks_init_lock(&call->a_args.lock.fl);
 211                         locks_init_lock(&call->a_res.lock.fl);
 212                         call->a_host = nlm_get_host(host);
 213                         return call;
 214                 }
 215                 if (signalled())
 216                         break;
 217                 printk("nlm_alloc_call: failed, waiting for memory\n");
 218                 schedule_timeout_interruptible(5*HZ);
 219         }
 220         return NULL;
 221 }
 222 
 223 void nlmclnt_release_call(struct nlm_rqst *call)
 224 {
 225         const struct nlmclnt_operations *nlmclnt_ops = call->a_host->h_nlmclnt_ops;
 226 
 227         if (!refcount_dec_and_test(&call->a_count))
 228                 return;
 229         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_release_call)
 230                 nlmclnt_ops->nlmclnt_release_call(call->a_callback_data);
 231         nlmclnt_release_host(call->a_host);
 232         nlmclnt_release_lockargs(call);
 233         kfree(call);
 234 }
 235 
 236 static void nlmclnt_rpc_release(void *data)
 237 {
 238         nlmclnt_release_call(data);
 239 }
 240 
 241 static int nlm_wait_on_grace(wait_queue_head_t *queue)
 242 {
 243         DEFINE_WAIT(wait);
 244         int status = -EINTR;
 245 
 246         prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 247         if (!signalled ()) {
 248                 schedule_timeout(NLMCLNT_GRACE_WAIT);
 249                 try_to_freeze();
 250                 if (!signalled ())
 251                         status = 0;
 252         }
 253         finish_wait(queue, &wait);
 254         return status;
 255 }
 256 
 257 /*
 258  * Generic NLM call
 259  */
 260 static int
 261 nlmclnt_call(const struct cred *cred, struct nlm_rqst *req, u32 proc)
 262 {
 263         struct nlm_host *host = req->a_host;
 264         struct rpc_clnt *clnt;
 265         struct nlm_args *argp = &req->a_args;
 266         struct nlm_res  *resp = &req->a_res;
 267         struct rpc_message msg = {
 268                 .rpc_argp       = argp,
 269                 .rpc_resp       = resp,
 270                 .rpc_cred       = cred,
 271         };
 272         int             status;
 273 
 274         dprintk("lockd: call procedure %d on %s\n",
 275                         (int)proc, host->h_name);
 276 
 277         do {
 278                 if (host->h_reclaiming && !argp->reclaim)
 279                         goto in_grace_period;
 280 
 281                 /* If we have no RPC client yet, create one. */
 282                 if ((clnt = nlm_bind_host(host)) == NULL)
 283                         return -ENOLCK;
 284                 msg.rpc_proc = &clnt->cl_procinfo[proc];
 285 
 286                 /* Perform the RPC call. If an error occurs, try again */
 287                 if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 288                         dprintk("lockd: rpc_call returned error %d\n", -status);
 289                         switch (status) {
 290                         case -EPROTONOSUPPORT:
 291                                 status = -EINVAL;
 292                                 break;
 293                         case -ECONNREFUSED:
 294                         case -ETIMEDOUT:
 295                         case -ENOTCONN:
 296                                 nlm_rebind_host(host);
 297                                 status = -EAGAIN;
 298                                 break;
 299                         case -ERESTARTSYS:
 300                                 return signalled () ? -EINTR : status;
 301                         default:
 302                                 break;
 303                         }
 304                         break;
 305                 } else
 306                 if (resp->status == nlm_lck_denied_grace_period) {
 307                         dprintk("lockd: server in grace period\n");
 308                         if (argp->reclaim) {
 309                                 printk(KERN_WARNING
 310                                      "lockd: spurious grace period reject?!\n");
 311                                 return -ENOLCK;
 312                         }
 313                 } else {
 314                         if (!argp->reclaim) {
 315                                 /* We appear to be out of the grace period */
 316                                 wake_up_all(&host->h_gracewait);
 317                         }
 318                         dprintk("lockd: server returns status %d\n",
 319                                 ntohl(resp->status));
 320                         return 0;       /* Okay, call complete */
 321                 }
 322 
 323 in_grace_period:
 324                 /*
 325                  * The server has rebooted and appears to be in the grace
 326                  * period during which locks are only allowed to be
 327                  * reclaimed.
 328                  * We can only back off and try again later.
 329                  */
 330                 status = nlm_wait_on_grace(&host->h_gracewait);
 331         } while (status == 0);
 332 
 333         return status;
 334 }
 335 
 336 /*
 337  * Generic NLM call, async version.
 338  */
 339 static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 340 {
 341         struct nlm_host *host = req->a_host;
 342         struct rpc_clnt *clnt;
 343         struct rpc_task_setup task_setup_data = {
 344                 .rpc_message = msg,
 345                 .callback_ops = tk_ops,
 346                 .callback_data = req,
 347                 .flags = RPC_TASK_ASYNC,
 348         };
 349 
 350         dprintk("lockd: call procedure %d on %s (async)\n",
 351                         (int)proc, host->h_name);
 352 
 353         /* If we have no RPC client yet, create one. */
 354         clnt = nlm_bind_host(host);
 355         if (clnt == NULL)
 356                 goto out_err;
 357         msg->rpc_proc = &clnt->cl_procinfo[proc];
 358         task_setup_data.rpc_client = clnt;
 359 
 360         /* bootstrap and kick off the async RPC call */
 361         return rpc_run_task(&task_setup_data);
 362 out_err:
 363         tk_ops->rpc_release(req);
 364         return ERR_PTR(-ENOLCK);
 365 }
 366 
 367 static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 368 {
 369         struct rpc_task *task;
 370 
 371         task = __nlm_async_call(req, proc, msg, tk_ops);
 372         if (IS_ERR(task))
 373                 return PTR_ERR(task);
 374         rpc_put_task(task);
 375         return 0;
 376 }
 377 
 378 /*
 379  * NLM asynchronous call.
 380  */
 381 int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 382 {
 383         struct rpc_message msg = {
 384                 .rpc_argp       = &req->a_args,
 385                 .rpc_resp       = &req->a_res,
 386         };
 387         return nlm_do_async_call(req, proc, &msg, tk_ops);
 388 }
 389 
 390 int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 391 {
 392         struct rpc_message msg = {
 393                 .rpc_argp       = &req->a_res,
 394         };
 395         return nlm_do_async_call(req, proc, &msg, tk_ops);
 396 }
 397 
 398 /*
 399  * NLM client asynchronous call.
 400  *
 401  * Note that although the calls are asynchronous, and are therefore
 402  *      guaranteed to complete, we still always attempt to wait for
 403  *      completion in order to be able to correctly track the lock
 404  *      state.
 405  */
 406 static int nlmclnt_async_call(const struct cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 407 {
 408         struct rpc_message msg = {
 409                 .rpc_argp       = &req->a_args,
 410                 .rpc_resp       = &req->a_res,
 411                 .rpc_cred       = cred,
 412         };
 413         struct rpc_task *task;
 414         int err;
 415 
 416         task = __nlm_async_call(req, proc, &msg, tk_ops);
 417         if (IS_ERR(task))
 418                 return PTR_ERR(task);
 419         err = rpc_wait_for_completion_task(task);
 420         rpc_put_task(task);
 421         return err;
 422 }
 423 
 424 /*
 425  * TEST for the presence of a conflicting lock
 426  */
 427 static int
 428 nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 429 {
 430         int     status;
 431 
 432         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 433         if (status < 0)
 434                 goto out;
 435 
 436         switch (req->a_res.status) {
 437                 case nlm_granted:
 438                         fl->fl_type = F_UNLCK;
 439                         break;
 440                 case nlm_lck_denied:
 441                         /*
 442                          * Report the conflicting lock back to the application.
 443                          */
 444                         fl->fl_start = req->a_res.lock.fl.fl_start;
 445                         fl->fl_end = req->a_res.lock.fl.fl_end;
 446                         fl->fl_type = req->a_res.lock.fl.fl_type;
 447                         fl->fl_pid = -req->a_res.lock.fl.fl_pid;
 448                         break;
 449                 default:
 450                         status = nlm_stat_to_errno(req->a_res.status);
 451         }
 452 out:
 453         nlmclnt_release_call(req);
 454         return status;
 455 }
 456 
 457 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 458 {
 459         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 460         new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 461         new->fl_u.nfs_fl.owner = nlmclnt_get_lockowner(fl->fl_u.nfs_fl.owner);
 462         list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 463         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 464 }
 465 
 466 static void nlmclnt_locks_release_private(struct file_lock *fl)
 467 {
 468         spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 469         list_del(&fl->fl_u.nfs_fl.list);
 470         spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 471         nlmclnt_put_lockowner(fl->fl_u.nfs_fl.owner);
 472 }
 473 
 474 static const struct file_lock_operations nlmclnt_lock_ops = {
 475         .fl_copy_lock = nlmclnt_locks_copy_lock,
 476         .fl_release_private = nlmclnt_locks_release_private,
 477 };
 478 
 479 static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 480 {
 481         fl->fl_u.nfs_fl.state = 0;
 482         fl->fl_u.nfs_fl.owner = nlmclnt_find_lockowner(host, fl->fl_owner);
 483         INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 484         fl->fl_ops = &nlmclnt_lock_ops;
 485 }
 486 
 487 static int do_vfs_lock(struct file_lock *fl)
 488 {
 489         return locks_lock_file_wait(fl->fl_file, fl);
 490 }
 491 
 492 /*
 493  * LOCK: Try to create a lock
 494  *
 495  *                      Programmer Harassment Alert
 496  *
 497  * When given a blocking lock request in a sync RPC call, the HPUX lockd
 498  * will faithfully return LCK_BLOCKED but never cares to notify us when
 499  * the lock could be granted. This way, our local process could hang
 500  * around forever waiting for the callback.
 501  *
 502  *  Solution A: Implement busy-waiting
 503  *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 504  *
 505  * For now I am implementing solution A, because I hate the idea of
 506  * re-implementing lockd for a third time in two months. The async
 507  * calls shouldn't be too hard to do, however.
 508  *
 509  * This is one of the lovely things about standards in the NFS area:
 510  * they're so soft and squishy you can't really blame HP for doing this.
 511  */
 512 static int
 513 nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 514 {
 515         const struct cred *cred = nfs_file_cred(fl->fl_file);
 516         struct nlm_host *host = req->a_host;
 517         struct nlm_res  *resp = &req->a_res;
 518         struct nlm_wait *block = NULL;
 519         unsigned char fl_flags = fl->fl_flags;
 520         unsigned char fl_type;
 521         int status = -ENOLCK;
 522 
 523         if (nsm_monitor(host) < 0)
 524                 goto out;
 525         req->a_args.state = nsm_local_state;
 526 
 527         fl->fl_flags |= FL_ACCESS;
 528         status = do_vfs_lock(fl);
 529         fl->fl_flags = fl_flags;
 530         if (status < 0)
 531                 goto out;
 532 
 533         block = nlmclnt_prepare_block(host, fl);
 534 again:
 535         /*
 536          * Initialise resp->status to a valid non-zero value,
 537          * since 0 == nlm_lck_granted
 538          */
 539         resp->status = nlm_lck_blocked;
 540         for(;;) {
 541                 /* Reboot protection */
 542                 fl->fl_u.nfs_fl.state = host->h_state;
 543                 status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 544                 if (status < 0)
 545                         break;
 546                 /* Did a reclaimer thread notify us of a server reboot? */
 547                 if (resp->status ==  nlm_lck_denied_grace_period)
 548                         continue;
 549                 if (resp->status != nlm_lck_blocked)
 550                         break;
 551                 /* Wait on an NLM blocking lock */
 552                 status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 553                 if (status < 0)
 554                         break;
 555                 if (resp->status != nlm_lck_blocked)
 556                         break;
 557         }
 558 
 559         /* if we were interrupted while blocking, then cancel the lock request
 560          * and exit
 561          */
 562         if (resp->status == nlm_lck_blocked) {
 563                 if (!req->a_args.block)
 564                         goto out_unlock;
 565                 if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 566                         goto out_unblock;
 567         }
 568 
 569         if (resp->status == nlm_granted) {
 570                 down_read(&host->h_rwsem);
 571                 /* Check whether or not the server has rebooted */
 572                 if (fl->fl_u.nfs_fl.state != host->h_state) {
 573                         up_read(&host->h_rwsem);
 574                         goto again;
 575                 }
 576                 /* Ensure the resulting lock will get added to granted list */
 577                 fl->fl_flags |= FL_SLEEP;
 578                 if (do_vfs_lock(fl) < 0)
 579                         printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 580                 up_read(&host->h_rwsem);
 581                 fl->fl_flags = fl_flags;
 582                 status = 0;
 583         }
 584         if (status < 0)
 585                 goto out_unlock;
 586         /*
 587          * EAGAIN doesn't make sense for sleeping locks, and in some
 588          * cases NLM_LCK_DENIED is returned for a permanent error.  So
 589          * turn it into an ENOLCK.
 590          */
 591         if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
 592                 status = -ENOLCK;
 593         else
 594                 status = nlm_stat_to_errno(resp->status);
 595 out_unblock:
 596         nlmclnt_finish_block(block);
 597 out:
 598         nlmclnt_release_call(req);
 599         return status;
 600 out_unlock:
 601         /* Fatal error: ensure that we remove the lock altogether */
 602         dprintk("lockd: lock attempt ended in fatal error.\n"
 603                 "       Attempting to unlock.\n");
 604         nlmclnt_finish_block(block);
 605         fl_type = fl->fl_type;
 606         fl->fl_type = F_UNLCK;
 607         down_read(&host->h_rwsem);
 608         do_vfs_lock(fl);
 609         up_read(&host->h_rwsem);
 610         fl->fl_type = fl_type;
 611         fl->fl_flags = fl_flags;
 612         nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 613         return status;
 614 }
 615 
 616 /*
 617  * RECLAIM: Try to reclaim a lock
 618  */
 619 int
 620 nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
 621                 struct nlm_rqst *req)
 622 {
 623         int             status;
 624 
 625         memset(req, 0, sizeof(*req));
 626         locks_init_lock(&req->a_args.lock.fl);
 627         locks_init_lock(&req->a_res.lock.fl);
 628         req->a_host  = host;
 629 
 630         /* Set up the argument struct */
 631         nlmclnt_setlockargs(req, fl);
 632         req->a_args.reclaim = 1;
 633 
 634         status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 635         if (status >= 0 && req->a_res.status == nlm_granted)
 636                 return 0;
 637 
 638         printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 639                                 "(errno %d, status %d)\n", fl->fl_pid,
 640                                 status, ntohl(req->a_res.status));
 641 
 642         /*
 643          * FIXME: This is a serious failure. We can
 644          *
 645          *  a.  Ignore the problem
 646          *  b.  Send the owning process some signal (Linux doesn't have
 647          *      SIGLOST, though...)
 648          *  c.  Retry the operation
 649          *
 650          * Until someone comes up with a simple implementation
 651          * for b or c, I'll choose option a.
 652          */
 653 
 654         return -ENOLCK;
 655 }
 656 
 657 /*
 658  * UNLOCK: remove an existing lock
 659  */
 660 static int
 661 nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 662 {
 663         struct nlm_host *host = req->a_host;
 664         struct nlm_res  *resp = &req->a_res;
 665         int status;
 666         unsigned char fl_flags = fl->fl_flags;
 667 
 668         /*
 669          * Note: the server is supposed to either grant us the unlock
 670          * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 671          * case, we want to unlock.
 672          */
 673         fl->fl_flags |= FL_EXISTS;
 674         down_read(&host->h_rwsem);
 675         status = do_vfs_lock(fl);
 676         up_read(&host->h_rwsem);
 677         fl->fl_flags = fl_flags;
 678         if (status == -ENOENT) {
 679                 status = 0;
 680                 goto out;
 681         }
 682 
 683         refcount_inc(&req->a_count);
 684         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 685                         NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 686         if (status < 0)
 687                 goto out;
 688 
 689         if (resp->status == nlm_granted)
 690                 goto out;
 691 
 692         if (resp->status != nlm_lck_denied_nolocks)
 693                 printk("lockd: unexpected unlock status: %d\n",
 694                         ntohl(resp->status));
 695         /* What to do now? I'm out of my depth... */
 696         status = -ENOLCK;
 697 out:
 698         nlmclnt_release_call(req);
 699         return status;
 700 }
 701 
 702 static void nlmclnt_unlock_prepare(struct rpc_task *task, void *data)
 703 {
 704         struct nlm_rqst *req = data;
 705         const struct nlmclnt_operations *nlmclnt_ops = req->a_host->h_nlmclnt_ops;
 706         bool defer_call = false;
 707 
 708         if (nlmclnt_ops && nlmclnt_ops->nlmclnt_unlock_prepare)
 709                 defer_call = nlmclnt_ops->nlmclnt_unlock_prepare(task, req->a_callback_data);
 710 
 711         if (!defer_call)
 712                 rpc_call_start(task);
 713 }
 714 
 715 static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 716 {
 717         struct nlm_rqst *req = data;
 718         u32 status = ntohl(req->a_res.status);
 719 
 720         if (RPC_SIGNALLED(task))
 721                 goto die;
 722 
 723         if (task->tk_status < 0) {
 724                 dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 725                 switch (task->tk_status) {
 726                 case -EACCES:
 727                 case -EIO:
 728                         goto die;
 729                 default:
 730                         goto retry_rebind;
 731                 }
 732         }
 733         if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 734                 rpc_delay(task, NLMCLNT_GRACE_WAIT);
 735                 goto retry_unlock;
 736         }
 737         if (status != NLM_LCK_GRANTED)
 738                 printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 739 die:
 740         return;
 741  retry_rebind:
 742         nlm_rebind_host(req->a_host);
 743  retry_unlock:
 744         rpc_restart_call(task);
 745 }
 746 
 747 static const struct rpc_call_ops nlmclnt_unlock_ops = {
 748         .rpc_call_prepare = nlmclnt_unlock_prepare,
 749         .rpc_call_done = nlmclnt_unlock_callback,
 750         .rpc_release = nlmclnt_rpc_release,
 751 };
 752 
 753 /*
 754  * Cancel a blocked lock request.
 755  * We always use an async RPC call for this in order not to hang a
 756  * process that has been Ctrl-C'ed.
 757  */
 758 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 759 {
 760         struct nlm_rqst *req;
 761         int status;
 762 
 763         dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 764                 "       Attempting to cancel lock.\n");
 765 
 766         req = nlm_alloc_call(host);
 767         if (!req)
 768                 return -ENOMEM;
 769         req->a_flags = RPC_TASK_ASYNC;
 770 
 771         nlmclnt_setlockargs(req, fl);
 772         req->a_args.block = block;
 773 
 774         refcount_inc(&req->a_count);
 775         status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 776                         NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 777         if (status == 0 && req->a_res.status == nlm_lck_denied)
 778                 status = -ENOLCK;
 779         nlmclnt_release_call(req);
 780         return status;
 781 }
 782 
 783 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 784 {
 785         struct nlm_rqst *req = data;
 786         u32 status = ntohl(req->a_res.status);
 787 
 788         if (RPC_SIGNALLED(task))
 789                 goto die;
 790 
 791         if (task->tk_status < 0) {
 792                 dprintk("lockd: CANCEL call error %d, retrying.\n",
 793                                         task->tk_status);
 794                 goto retry_cancel;
 795         }
 796 
 797         dprintk("lockd: cancel status %u (task %u)\n",
 798                         status, task->tk_pid);
 799 
 800         switch (status) {
 801         case NLM_LCK_GRANTED:
 802         case NLM_LCK_DENIED_GRACE_PERIOD:
 803         case NLM_LCK_DENIED:
 804                 /* Everything's good */
 805                 break;
 806         case NLM_LCK_DENIED_NOLOCKS:
 807                 dprintk("lockd: CANCEL failed (server has no locks)\n");
 808                 goto retry_cancel;
 809         default:
 810                 printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 811                         status);
 812         }
 813 
 814 die:
 815         return;
 816 
 817 retry_cancel:
 818         /* Don't ever retry more than 3 times */
 819         if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 820                 goto die;
 821         nlm_rebind_host(req->a_host);
 822         rpc_restart_call(task);
 823         rpc_delay(task, 30 * HZ);
 824 }
 825 
 826 static const struct rpc_call_ops nlmclnt_cancel_ops = {
 827         .rpc_call_done = nlmclnt_cancel_callback,
 828         .rpc_release = nlmclnt_rpc_release,
 829 };
 830 
 831 /*
 832  * Convert an NLM status code to a generic kernel errno
 833  */
 834 static int
 835 nlm_stat_to_errno(__be32 status)
 836 {
 837         switch(ntohl(status)) {
 838         case NLM_LCK_GRANTED:
 839                 return 0;
 840         case NLM_LCK_DENIED:
 841                 return -EAGAIN;
 842         case NLM_LCK_DENIED_NOLOCKS:
 843         case NLM_LCK_DENIED_GRACE_PERIOD:
 844                 return -ENOLCK;
 845         case NLM_LCK_BLOCKED:
 846                 printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 847                 return -ENOLCK;
 848 #ifdef CONFIG_LOCKD_V4
 849         case NLM_DEADLCK:
 850                 return -EDEADLK;
 851         case NLM_ROFS:
 852                 return -EROFS;
 853         case NLM_STALE_FH:
 854                 return -ESTALE;
 855         case NLM_FBIG:
 856                 return -EOVERFLOW;
 857         case NLM_FAILED:
 858                 return -ENOLCK;
 859 #endif
 860         }
 861         printk(KERN_NOTICE "lockd: unexpected server status %d\n",
 862                  ntohl(status));
 863         return -ENOLCK;
 864 }