git.oblomov.eu Git - linux-2.6/blob - fs/lockd/svclock.c

   1 /*
   2  * linux/fs/lockd/svclock.c
   3  *
   4  * Handling of server-side locks, mostly of the blocked variety.
   5  * This is the ugliest part of lockd because we tread on very thin ice.
   6  * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
   7  * IMNSHO introducing the grant callback into the NLM protocol was one
   8  * of the worst ideas Sun ever had. Except maybe for the idea of doing
   9  * NFS file locking at all.
  10  *
  11  * I'm trying hard to avoid race conditions by protecting most accesses
  12  * to a file's list of blocked locks through a semaphore. The global
  13  * list of blocked locks is not protected in this fashion however.
  14  * Therefore, some functions (such as the RPC callback for the async grant
  15  * call) move blocked locks towards the head of the list *while some other
  16  * process might be traversing it*. This should not be a problem in
  17  * practice, because this will only cause functions traversing the list
  18  * to visit some blocks twice.
  19  *
  20  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
  21  */
  22
  23 #include <linux/types.h>
  24 #include <linux/errno.h>
  25 #include <linux/kernel.h>
  26 #include <linux/sched.h>
  27 #include <linux/smp_lock.h>
  28 #include <linux/sunrpc/clnt.h>
  29 #include <linux/sunrpc/svc.h>
  30 #include <linux/lockd/nlm.h>
  31 #include <linux/lockd/lockd.h>
  32
  33 #define NLMDBG_FACILITY         NLMDBG_SVCLOCK
  34
  35 #ifdef CONFIG_LOCKD_V4
  36 #define nlm_deadlock    nlm4_deadlock
  37 #else
  38 #define nlm_deadlock    nlm_lck_denied
  39 #endif
  40
  41 static void nlmsvc_release_block(struct nlm_block *block);
  42 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
  43 static void     nlmsvc_remove_block(struct nlm_block *block);
  44
  45 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
  46 static void nlmsvc_freegrantargs(struct nlm_rqst *call);
  47 static const struct rpc_call_ops nlmsvc_grant_ops;
  48
  49 /*
  50  * The list of blocked locks to retry
  51  */
  52 static LIST_HEAD(nlm_blocked);
  53
  54 /*
  55  * Insert a blocked lock into the global list
  56  */
  57 static void
  58 nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
  59 {
  60         struct nlm_block *b;
  61         struct list_head *pos;
  62
  63         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  64         if (list_empty(&block->b_list)) {
  65                 kref_get(&block->b_count);
  66         } else {
  67                 list_del_init(&block->b_list);
  68         }
  69
  70         pos = &nlm_blocked;
  71         if (when != NLM_NEVER) {
  72                 if ((when += jiffies) == NLM_NEVER)
  73                         when ++;
  74                 list_for_each(pos, &nlm_blocked) {
  75                         b = list_entry(pos, struct nlm_block, b_list);
  76                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
  77                                 break;
  78                 }
  79                 /* On normal exit from the loop, pos == &nlm_blocked,
  80                  * so we will be adding to the end of the list - good
  81                  */
  82         }
  83
  84         list_add_tail(&block->b_list, pos);
  85         block->b_when = when;
  86 }
  87
  88 /*
  89  * Remove a block from the global list
  90  */
  91 static inline void
  92 nlmsvc_remove_block(struct nlm_block *block)
  93 {
  94         if (!list_empty(&block->b_list)) {
  95                 list_del_init(&block->b_list);
  96                 nlmsvc_release_block(block);
  97         }
  98 }
  99
 100 /*
 101  * Find a block for a given lock
 102  */
 103 static struct nlm_block *
 104 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
 105 {
 106         struct nlm_block        *block;
 107         struct file_lock        *fl;
 108
 109         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 110                                 file, lock->fl.fl_pid,
 111                                 (long long)lock->fl.fl_start,
 112                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
 113         list_for_each_entry(block, &nlm_blocked, b_list) {
 114                 fl = &block->b_call->a_args.lock.fl;
 115                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 116                                 block->b_file, fl->fl_pid,
 117                                 (long long)fl->fl_start,
 118                                 (long long)fl->fl_end, fl->fl_type,
 119                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
 120                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 121                         kref_get(&block->b_count);
 122                         return block;
 123                 }
 124         }
 125
 126         return NULL;
 127 }
 128
 129 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 130 {
 131         if(a->len != b->len)
 132                 return 0;
 133         if(memcmp(a->data,b->data,a->len))
 134                 return 0;
 135         return 1;
 136 }
 137
 138 /*
 139  * Find a block with a given NLM cookie.
 140  */
 141 static inline struct nlm_block *
 142 nlmsvc_find_block(struct nlm_cookie *cookie)
 143 {
 144         struct nlm_block *block;
 145
 146         list_for_each_entry(block, &nlm_blocked, b_list) {
 147                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
 148                         goto found;
 149         }
 150
 151         return NULL;
 152
 153 found:
 154         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
 155         kref_get(&block->b_count);
 156         return block;
 157 }
 158
 159 /*
 160  * Create a block and initialize it.
 161  *
 162  * Note: we explicitly set the cookie of the grant reply to that of
 163  * the blocked lock request. The spec explicitly mentions that the client
 164  * should _not_ rely on the callback containing the same cookie as the
 165  * request, but (as I found out later) that's because some implementations
 166  * do just this. Never mind the standards comittees, they support our
 167  * logging industries.
 168  *
 169  * 10 years later: I hope we can safely ignore these old and broken
 170  * clients by now. Let's fix this so we can uniquely identify an incoming
 171  * GRANTED_RES message by cookie, without having to rely on the client's IP
 172  * address. --okir
 173  */
 174 static inline struct nlm_block *
 175 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
 176                                 struct nlm_lock *lock, struct nlm_cookie *cookie)
 177 {
 178         struct nlm_block        *block;
 179         struct nlm_host         *host;
 180         struct nlm_rqst         *call = NULL;
 181
 182         /* Create host handle for callback */
 183         host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len);
 184         if (host == NULL)
 185                 return NULL;
 186
 187         call = nlm_alloc_call(host);
 188         if (call == NULL)
 189                 return NULL;
 190
 191         /* Allocate memory for block, and initialize arguments */
 192         block = kzalloc(sizeof(*block), GFP_KERNEL);
 193         if (block == NULL)
 194                 goto failed;
 195         kref_init(&block->b_count);
 196         INIT_LIST_HEAD(&block->b_list);
 197         INIT_LIST_HEAD(&block->b_flist);
 198
 199         if (!nlmsvc_setgrantargs(call, lock))
 200                 goto failed_free;
 201
 202         /* Set notifier function for VFS, and init args */
 203         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
 204         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
 205         nlmclnt_next_cookie(&call->a_args.cookie);
 206
 207         dprintk("lockd: created block %p...\n", block);
 208
 209         /* Create and initialize the block */
 210         block->b_daemon = rqstp->rq_server;
 211         block->b_host   = host;
 212         block->b_file   = file;
 213         file->f_count++;
 214
 215         /* Add to file's list of blocks */
 216         list_add(&block->b_flist, &file->f_blocks);
 217
 218         /* Set up RPC arguments for callback */
 219         block->b_call = call;
 220         call->a_flags   = RPC_TASK_ASYNC;
 221         call->a_block = block;
 222
 223         return block;
 224
 225 failed_free:
 226         kfree(block);
 227 failed:
 228         nlm_release_call(call);
 229         return NULL;
 230 }
 231
 232 /*
 233  * Delete a block. If the lock was cancelled or the grant callback
 234  * failed, unlock is set to 1.
 235  * It is the caller's responsibility to check whether the file
 236  * can be closed hereafter.
 237  */
 238 static int nlmsvc_unlink_block(struct nlm_block *block)
 239 {
 240         int status;
 241         dprintk("lockd: unlinking block %p...\n", block);
 242
 243         /* Remove block from list */
 244         status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
 245         nlmsvc_remove_block(block);
 246         return status;
 247 }
 248
 249 static void nlmsvc_free_block(struct kref *kref)
 250 {
 251         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
 252         struct nlm_file         *file = block->b_file;
 253
 254         dprintk("lockd: freeing block %p...\n", block);
 255
 256         /* Remove block from file's list of blocks */
 257         mutex_lock(&file->f_mutex);
 258         list_del_init(&block->b_flist);
 259         mutex_unlock(&file->f_mutex);
 260
 261         nlmsvc_freegrantargs(block->b_call);
 262         nlm_release_call(block->b_call);
 263         nlm_release_file(block->b_file);
 264         kfree(block);
 265 }
 266
 267 static void nlmsvc_release_block(struct nlm_block *block)
 268 {
 269         if (block != NULL)
 270                 kref_put(&block->b_count, nlmsvc_free_block);
 271 }
 272
 273 /*
 274  * Loop over all blocks and delete blocks held by
 275  * a matching host.
 276  */
 277 void nlmsvc_traverse_blocks(struct nlm_host *host,
 278                         struct nlm_file *file,
 279                         nlm_host_match_fn_t match)
 280 {
 281         struct nlm_block *block, *next;
 282
 283 restart:
 284         mutex_lock(&file->f_mutex);
 285         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
 286                 if (!match(block->b_host, host))
 287                         continue;
 288                 /* Do not destroy blocks that are not on
 289                  * the global retry list - why? */
 290                 if (list_empty(&block->b_list))
 291                         continue;
 292                 kref_get(&block->b_count);
 293                 mutex_unlock(&file->f_mutex);
 294                 nlmsvc_unlink_block(block);
 295                 nlmsvc_release_block(block);
 296                 goto restart;
 297         }
 298         mutex_unlock(&file->f_mutex);
 299 }
 300
 301 /*
 302  * Initialize arguments for GRANTED call. The nlm_rqst structure
 303  * has been cleared already.
 304  */
 305 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
 306 {
 307         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
 308         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
 309         call->a_args.lock.caller = utsname()->nodename;
 310         call->a_args.lock.oh.len = lock->oh.len;
 311
 312         /* set default data area */
 313         call->a_args.lock.oh.data = call->a_owner;
 314         call->a_args.lock.svid = lock->fl.fl_pid;
 315
 316         if (lock->oh.len > NLMCLNT_OHSIZE) {
 317                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
 318                 if (!data)
 319                         return 0;
 320                 call->a_args.lock.oh.data = (u8 *) data;
 321         }
 322
 323         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
 324         return 1;
 325 }
 326
 327 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 328 {
 329         if (call->a_args.lock.oh.data != call->a_owner)
 330                 kfree(call->a_args.lock.oh.data);
 331 }
 332
 333 /*
 334  * Attempt to establish a lock, and if it can't be granted, block it
 335  * if required.
 336  */
 337 __be32
 338 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 339                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
 340 {
 341         struct nlm_block        *block, *newblock = NULL;
 342         int                     error;
 343         __be32                  ret;
 344
 345         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
 346                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 347                                 file->f_file->f_path.dentry->d_inode->i_ino,
 348                                 lock->fl.fl_type, lock->fl.fl_pid,
 349                                 (long long)lock->fl.fl_start,
 350                                 (long long)lock->fl.fl_end,
 351                                 wait);
 352
 353
 354         lock->fl.fl_flags &= ~FL_SLEEP;
 355 again:
 356         /* Lock file against concurrent access */
 357         mutex_lock(&file->f_mutex);
 358         /* Get existing block (in case client is busy-waiting) */
 359         block = nlmsvc_lookup_block(file, lock);
 360         if (block == NULL) {
 361                 if (newblock != NULL)
 362                         lock = &newblock->b_call->a_args.lock;
 363         } else
 364                 lock = &block->b_call->a_args.lock;
 365
 366         error = posix_lock_file(file->f_file, &lock->fl);
 367         lock->fl.fl_flags &= ~FL_SLEEP;
 368
 369         dprintk("lockd: posix_lock_file returned %d\n", error);
 370
 371         switch(error) {
 372                 case 0:
 373                         ret = nlm_granted;
 374                         goto out;
 375                 case -EAGAIN:
 376                         break;
 377                 case -EDEADLK:
 378                         ret = nlm_deadlock;
 379                         goto out;
 380                 default:                        /* includes ENOLCK */
 381                         ret = nlm_lck_denied_nolocks;
 382                         goto out;
 383         }
 384
 385         ret = nlm_lck_denied;
 386         if (!wait)
 387                 goto out;
 388
 389         ret = nlm_lck_blocked;
 390         if (block != NULL)
 391                 goto out;
 392
 393         /* If we don't have a block, create and initialize it. Then
 394          * retry because we may have slept in kmalloc. */
 395         /* We have to release f_mutex as nlmsvc_create_block may try to
 396          * to claim it while doing host garbage collection */
 397         if (newblock == NULL) {
 398                 mutex_unlock(&file->f_mutex);
 399                 dprintk("lockd: blocking on this lock (allocating).\n");
 400                 if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))
 401                         return nlm_lck_denied_nolocks;
 402                 goto again;
 403         }
 404
 405         /* Append to list of blocked */
 406         nlmsvc_insert_block(newblock, NLM_NEVER);
 407 out:
 408         mutex_unlock(&file->f_mutex);
 409         nlmsvc_release_block(newblock);
 410         nlmsvc_release_block(block);
 411         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 412         return ret;
 413 }
 414
 415 /*
 416  * Test for presence of a conflicting lock.
 417  */
 418 __be32
 419 nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
 420                                        struct nlm_lock *conflock)
 421 {
 422         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 423                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 424                                 file->f_file->f_path.dentry->d_inode->i_ino,
 425                                 lock->fl.fl_type,
 426                                 (long long)lock->fl.fl_start,
 427                                 (long long)lock->fl.fl_end);
 428
 429         if (posix_test_lock(file->f_file, &lock->fl, &conflock->fl)) {
 430                 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 431                                 conflock->fl.fl_type,
 432                                 (long long)conflock->fl.fl_start,
 433                                 (long long)conflock->fl.fl_end);
 434                 conflock->caller = "somehost";  /* FIXME */
 435                 conflock->len = strlen(conflock->caller);
 436                 conflock->oh.len = 0;           /* don't return OH info */
 437                 conflock->svid = conflock->fl.fl_pid;
 438                 return nlm_lck_denied;
 439         }
 440
 441         return nlm_granted;
 442 }
 443
 444 /*
 445  * Remove a lock.
 446  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 447  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 448  * afterwards. In this case the block will still be there, and hence
 449  * must be removed.
 450  */
 451 __be32
 452 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
 453 {
 454         int     error;
 455
 456         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 457                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 458                                 file->f_file->f_path.dentry->d_inode->i_ino,
 459                                 lock->fl.fl_pid,
 460                                 (long long)lock->fl.fl_start,
 461                                 (long long)lock->fl.fl_end);
 462
 463         /* First, cancel any lock that might be there */
 464         nlmsvc_cancel_blocked(file, lock);
 465
 466         lock->fl.fl_type = F_UNLCK;
 467         error = posix_lock_file(file->f_file, &lock->fl);
 468
 469         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 470 }
 471
 472 /*
 473  * Cancel a previously blocked request.
 474  *
 475  * A cancel request always overrides any grant that may currently
 476  * be in progress.
 477  * The calling procedure must check whether the file can be closed.
 478  */
 479 __be32
 480 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
 481 {
 482         struct nlm_block        *block;
 483         int status = 0;
 484
 485         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 486                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
 487                                 file->f_file->f_path.dentry->d_inode->i_ino,
 488                                 lock->fl.fl_pid,
 489                                 (long long)lock->fl.fl_start,
 490                                 (long long)lock->fl.fl_end);
 491
 492         mutex_lock(&file->f_mutex);
 493         block = nlmsvc_lookup_block(file, lock);
 494         mutex_unlock(&file->f_mutex);
 495         if (block != NULL) {
 496                 status = nlmsvc_unlink_block(block);
 497                 nlmsvc_release_block(block);
 498         }
 499         return status ? nlm_lck_denied : nlm_granted;
 500 }
 501
 502 /*
 503  * Unblock a blocked lock request. This is a callback invoked from the
 504  * VFS layer when a lock on which we blocked is removed.
 505  *
 506  * This function doesn't grant the blocked lock instantly, but rather moves
 507  * the block to the head of nlm_blocked where it can be picked up by lockd.
 508  */
 509 static void
 510 nlmsvc_notify_blocked(struct file_lock *fl)
 511 {
 512         struct nlm_block        *block;
 513
 514         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 515         list_for_each_entry(block, &nlm_blocked, b_list) {
 516                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 517                         nlmsvc_insert_block(block, 0);
 518                         svc_wake_up(block->b_daemon);
 519                         return;
 520                 }
 521         }
 522
 523         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 524 }
 525
 526 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 527 {
 528         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
 529 }
 530
 531 struct lock_manager_operations nlmsvc_lock_operations = {
 532         .fl_compare_owner = nlmsvc_same_owner,
 533         .fl_notify = nlmsvc_notify_blocked,
 534 };
 535
 536 /*
 537  * Try to claim a lock that was previously blocked.
 538  *
 539  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 540  * RPC thread when notifying the client. This seems like overkill...
 541  * Here's why:
 542  *  -   we don't want to use a synchronous RPC thread, otherwise
 543  *      we might find ourselves hanging on a dead portmapper.
 544  *  -   Some lockd implementations (e.g. HP) don't react to
 545  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 546  */
 547 static void
 548 nlmsvc_grant_blocked(struct nlm_block *block)
 549 {
 550         struct nlm_file         *file = block->b_file;
 551         struct nlm_lock         *lock = &block->b_call->a_args.lock;
 552         int                     error;
 553
 554         dprintk("lockd: grant blocked lock %p\n", block);
 555
 556         /* Unlink block request from list */
 557         nlmsvc_unlink_block(block);
 558
 559         /* If b_granted is true this means we've been here before.
 560          * Just retry the grant callback, possibly refreshing the RPC
 561          * binding */
 562         if (block->b_granted) {
 563                 nlm_rebind_host(block->b_host);
 564                 goto callback;
 565         }
 566
 567         /* Try the lock operation again */
 568         lock->fl.fl_flags |= FL_SLEEP;
 569         error = posix_lock_file(file->f_file, &lock->fl);
 570         lock->fl.fl_flags &= ~FL_SLEEP;
 571
 572         switch (error) {
 573         case 0:
 574                 break;
 575         case -EAGAIN:
 576                 dprintk("lockd: lock still blocked\n");
 577                 nlmsvc_insert_block(block, NLM_NEVER);
 578                 return;
 579         default:
 580                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 581                                 -error, __FUNCTION__);
 582                 nlmsvc_insert_block(block, 10 * HZ);
 583                 return;
 584         }
 585
 586 callback:
 587         /* Lock was granted by VFS. */
 588         dprintk("lockd: GRANTing blocked lock.\n");
 589         block->b_granted = 1;
 590
 591         /* Schedule next grant callback in 30 seconds */
 592         nlmsvc_insert_block(block, 30 * HZ);
 593
 594         /* Call the client */
 595         kref_get(&block->b_count);
 596         nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG, &nlmsvc_grant_ops);
 597 }
 598
 599 /*
 600  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 601  * RPC call has succeeded or timed out.
 602  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 603  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 604  * chain once more in order to have it removed by lockd itself (which can
 605  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 606  */
 607 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 608 {
 609         struct nlm_rqst         *call = data;
 610         struct nlm_block        *block = call->a_block;
 611         unsigned long           timeout;
 612
 613         dprintk("lockd: GRANT_MSG RPC callback\n");
 614
 615         /* Technically, we should down the file semaphore here. Since we
 616          * move the block towards the head of the queue only, no harm
 617          * can be done, though. */
 618         if (task->tk_status < 0) {
 619                 /* RPC error: Re-insert for retransmission */
 620                 timeout = 10 * HZ;
 621         } else {
 622                 /* Call was successful, now wait for client callback */
 623                 timeout = 60 * HZ;
 624         }
 625         nlmsvc_insert_block(block, timeout);
 626         svc_wake_up(block->b_daemon);
 627 }
 628
 629 static void nlmsvc_grant_release(void *data)
 630 {
 631         struct nlm_rqst         *call = data;
 632
 633         nlmsvc_release_block(call->a_block);
 634 }
 635
 636 static const struct rpc_call_ops nlmsvc_grant_ops = {
 637         .rpc_call_done = nlmsvc_grant_callback,
 638         .rpc_release = nlmsvc_grant_release,
 639 };
 640
 641 /*
 642  * We received a GRANT_RES callback. Try to find the corresponding
 643  * block.
 644  */
 645 void
 646 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
 647 {
 648         struct nlm_block        *block;
 649
 650         dprintk("grant_reply: looking for cookie %x, s=%d \n",
 651                 *(unsigned int *)(cookie->data), status);
 652         if (!(block = nlmsvc_find_block(cookie)))
 653                 return;
 654
 655         if (block) {
 656                 if (status == nlm_lck_denied_grace_period) {
 657                         /* Try again in a couple of seconds */
 658                         nlmsvc_insert_block(block, 10 * HZ);
 659                 } else {
 660                         /* Lock is now held by client, or has been rejected.
 661                          * In both cases, the block should be removed. */
 662                         nlmsvc_unlink_block(block);
 663                 }
 664         }
 665         nlmsvc_release_block(block);
 666 }
 667
 668 /*
 669  * Retry all blocked locks that have been notified. This is where lockd
 670  * picks up locks that can be granted, or grant notifications that must
 671  * be retransmitted.
 672  */
 673 unsigned long
 674 nlmsvc_retry_blocked(void)
 675 {
 676         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
 677         struct nlm_block *block;
 678
 679         while (!list_empty(&nlm_blocked)) {
 680                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
 681
 682                 if (block->b_when == NLM_NEVER)
 683                         break;
 684                 if (time_after(block->b_when,jiffies)) {
 685                         timeout = block->b_when - jiffies;
 686                         break;
 687                 }
 688
 689                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
 690                         block, block->b_when);
 691                 kref_get(&block->b_count);
 692                 nlmsvc_grant_blocked(block);
 693                 nlmsvc_release_block(block);
 694         }
 695
 696         return timeout;
 697 }