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   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/config.h>
  24 #include <linux/types.h>
  25 #include <linux/errno.h>
  26 #include <linux/kernel.h>
  27 #include <linux/sched.h>
  28 #include <linux/smp_lock.h>
  29 #include <linux/sunrpc/clnt.h>
  30 #include <linux/sunrpc/svc.h>
  31 #include <linux/lockd/nlm.h>
  32 #include <linux/lockd/lockd.h>
  33
  34 #define NLMDBG_FACILITY         NLMDBG_SVCLOCK
  35
  36 #ifdef CONFIG_LOCKD_V4
  37 #define nlm_deadlock    nlm4_deadlock
  38 #else
  39 #define nlm_deadlock    nlm_lck_denied
  40 #endif
  41
  42 static void nlmsvc_release_block(struct nlm_block *block);
  43 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
  44 static int      nlmsvc_remove_block(struct nlm_block *block);
  45
  46 static const struct rpc_call_ops nlmsvc_grant_ops;
  47
  48 /*
  49  * The list of blocked locks to retry
  50  */
  51 static struct nlm_block *       nlm_blocked;
  52
  53 /*
  54  * Insert a blocked lock into the global list
  55  */
  56 static void
  57 nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
  58 {
  59         struct nlm_block **bp, *b;
  60
  61         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  62         kref_get(&block->b_count);
  63         if (block->b_queued)
  64                 nlmsvc_remove_block(block);
  65         bp = &nlm_blocked;
  66         if (when != NLM_NEVER) {
  67                 if ((when += jiffies) == NLM_NEVER)
  68                         when ++;
  69                 while ((b = *bp) && time_before_eq(b->b_when,when) && b->b_when != NLM_NEVER)
  70                         bp = &b->b_next;
  71         } else
  72                 while ((b = *bp) != 0)
  73                         bp = &b->b_next;
  74
  75         block->b_queued = 1;
  76         block->b_when = when;
  77         block->b_next = b;
  78         *bp = block;
  79 }
  80
  81 /*
  82  * Remove a block from the global list
  83  */
  84 static int
  85 nlmsvc_remove_block(struct nlm_block *block)
  86 {
  87         struct nlm_block **bp, *b;
  88
  89         if (!block->b_queued)
  90                 return 1;
  91         for (bp = &nlm_blocked; (b = *bp) != 0; bp = &b->b_next) {
  92                 if (b == block) {
  93                         *bp = block->b_next;
  94                         block->b_queued = 0;
  95                         nlmsvc_release_block(block);
  96                         return 1;
  97                 }
  98         }
  99
 100         return 0;
 101 }
 102
 103 /*
 104  * Find a block for a given lock and optionally remove it from
 105  * the list.
 106  */
 107 static struct nlm_block *
 108 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock, int remove)
 109 {
 110         struct nlm_block        **head, *block;
 111         struct file_lock        *fl;
 112
 113         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 114                                 file, lock->fl.fl_pid,
 115                                 (long long)lock->fl.fl_start,
 116                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
 117         for (head = &nlm_blocked; (block = *head) != 0; head = &block->b_next) {
 118                 fl = &block->b_call.a_args.lock.fl;
 119                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 120                                 block->b_file, fl->fl_pid,
 121                                 (long long)fl->fl_start,
 122                                 (long long)fl->fl_end, fl->fl_type,
 123                                 nlmdbg_cookie2a(&block->b_call.a_args.cookie));
 124                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 125                         if (remove) {
 126                                 *head = block->b_next;
 127                                 block->b_queued = 0;
 128                         }
 129                         kref_get(&block->b_count);
 130                         return block;
 131                 }
 132         }
 133
 134         return NULL;
 135 }
 136
 137 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 138 {
 139         if(a->len != b->len)
 140                 return 0;
 141         if(memcmp(a->data,b->data,a->len))
 142                 return 0;
 143         return 1;
 144 }
 145
 146 /*
 147  * Find a block with a given NLM cookie.
 148  */
 149 static inline struct nlm_block *
 150 nlmsvc_find_block(struct nlm_cookie *cookie,  struct sockaddr_in *sin)
 151 {
 152         struct nlm_block *block;
 153
 154         for (block = nlm_blocked; block; block = block->b_next) {
 155                 dprintk("cookie: head of blocked queue %p, block %p\n",
 156                         nlm_blocked, block);
 157                 if (nlm_cookie_match(&block->b_call.a_args.cookie,cookie)
 158                                 && nlm_cmp_addr(sin, &block->b_host->h_addr))
 159                         break;
 160         }
 161
 162         if (block != NULL)
 163                 kref_get(&block->b_count);
 164         return block;
 165 }
 166
 167 /*
 168  * Create a block and initialize it.
 169  *
 170  * Note: we explicitly set the cookie of the grant reply to that of
 171  * the blocked lock request. The spec explicitly mentions that the client
 172  * should _not_ rely on the callback containing the same cookie as the
 173  * request, but (as I found out later) that's because some implementations
 174  * do just this. Never mind the standards comittees, they support our
 175  * logging industries.
 176  */
 177 static inline struct nlm_block *
 178 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
 179                                 struct nlm_lock *lock, struct nlm_cookie *cookie)
 180 {
 181         struct nlm_block        *block;
 182         struct nlm_host         *host;
 183         struct nlm_rqst         *call;
 184
 185         /* Create host handle for callback */
 186         host = nlmclnt_lookup_host(&rqstp->rq_addr,
 187                                 rqstp->rq_prot, rqstp->rq_vers);
 188         if (host == NULL)
 189                 return NULL;
 190
 191         /* Allocate memory for block, and initialize arguments */
 192         if (!(block = (struct nlm_block *) kmalloc(sizeof(*block), GFP_KERNEL)))
 193                 goto failed;
 194         memset(block, 0, sizeof(*block));
 195         locks_init_lock(&block->b_call.a_args.lock.fl);
 196         locks_init_lock(&block->b_call.a_res.lock.fl);
 197         kref_init(&block->b_count);
 198
 199         if (!nlmclnt_setgrantargs(&block->b_call, lock))
 200                 goto failed_free;
 201
 202         /* Set notifier function for VFS, and init args */
 203         block->b_call.a_args.lock.fl.fl_flags |= FL_SLEEP;
 204         block->b_call.a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
 205         block->b_call.a_args.cookie = *cookie;  /* see above */
 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
 214         /* Add to file's list of blocks */
 215         block->b_fnext  = file->f_blocks;
 216         file->f_blocks  = block;
 217
 218         /* Set up RPC arguments for callback */
 219         call = &block->b_call;
 220         call->a_host    = host;
 221         call->a_flags   = RPC_TASK_ASYNC;
 222
 223         return block;
 224
 225 failed_free:
 226         kfree(block);
 227 failed:
 228         nlm_release_host(host);
 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         struct nlm_block        **bp;
 254
 255         dprintk("lockd: freeing block %p...\n", block);
 256
 257         /* Remove block from file's list of blocks */
 258         for (bp = &file->f_blocks; *bp; bp = &(*bp)->b_fnext) {
 259                 if (*bp == block) {
 260                         *bp = block->b_fnext;
 261                         break;
 262                 }
 263         }
 264
 265         if (block->b_host)
 266                 nlm_release_host(block->b_host);
 267         nlmclnt_freegrantargs(&block->b_call);
 268         kfree(block);
 269 }
 270
 271 static void nlmsvc_release_block(struct nlm_block *block)
 272 {
 273         if (block != NULL)
 274                 kref_put(&block->b_count, nlmsvc_free_block);
 275 }
 276
 277 /*
 278  * Loop over all blocks and perform the action specified.
 279  * (NLM_ACT_CHECK handled by nlmsvc_inspect_file).
 280  */
 281 int
 282 nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action)
 283 {
 284         struct nlm_block        *block, *next;
 285         /* XXX: Will everything get cleaned up if we don't unlock here? */
 286
 287         down(&file->f_sema);
 288         for (block = file->f_blocks; block; block = next) {
 289                 next = block->b_fnext;
 290                 if (action == NLM_ACT_MARK)
 291                         block->b_host->h_inuse = 1;
 292                 else if (action == NLM_ACT_UNLOCK) {
 293                         if (host == NULL || host == block->b_host)
 294                                 nlmsvc_unlink_block(block);
 295                 }
 296         }
 297         up(&file->f_sema);
 298         return 0;
 299 }
 300
 301 /*
 302  * Attempt to establish a lock, and if it can't be granted, block it
 303  * if required.
 304  */
 305 u32
 306 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 307                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
 308 {
 309         struct nlm_block        *block, *newblock = NULL;
 310         int                     error;
 311         u32                     ret;
 312
 313         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
 314                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
 315                                 file->f_file->f_dentry->d_inode->i_ino,
 316                                 lock->fl.fl_type, lock->fl.fl_pid,
 317                                 (long long)lock->fl.fl_start,
 318                                 (long long)lock->fl.fl_end,
 319                                 wait);
 320
 321
 322         lock->fl.fl_flags &= ~FL_SLEEP;
 323 again:
 324         /* Lock file against concurrent access */
 325         down(&file->f_sema);
 326         /* Get existing block (in case client is busy-waiting) */
 327         block = nlmsvc_lookup_block(file, lock, 0);
 328         if (block == NULL) {
 329                 if (newblock != NULL)
 330                         lock = &newblock->b_call.a_args.lock;
 331         } else
 332                 lock = &block->b_call.a_args.lock;
 333
 334         error = posix_lock_file(file->f_file, &lock->fl);
 335         lock->fl.fl_flags &= ~FL_SLEEP;
 336
 337         dprintk("lockd: posix_lock_file returned %d\n", error);
 338
 339         switch(error) {
 340                 case 0:
 341                         ret = nlm_granted;
 342                         goto out;
 343                 case -EAGAIN:
 344                         break;
 345                 case -EDEADLK:
 346                         ret = nlm_deadlock;
 347                         goto out;
 348                 default:                        /* includes ENOLCK */
 349                         ret = nlm_lck_denied_nolocks;
 350                         goto out;
 351         }
 352
 353         ret = nlm_lck_denied;
 354         if (!wait)
 355                 goto out;
 356
 357         ret = nlm_lck_blocked;
 358         if (block != NULL)
 359                 goto out;
 360
 361         /* If we don't have a block, create and initialize it. Then
 362          * retry because we may have slept in kmalloc. */
 363         /* We have to release f_sema as nlmsvc_create_block may try to
 364          * to claim it while doing host garbage collection */
 365         if (newblock == NULL) {
 366                 up(&file->f_sema);
 367                 dprintk("lockd: blocking on this lock (allocating).\n");
 368                 if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))
 369                         return nlm_lck_denied_nolocks;
 370                 goto again;
 371         }
 372
 373         /* Append to list of blocked */
 374         nlmsvc_insert_block(newblock, NLM_NEVER);
 375 out:
 376         up(&file->f_sema);
 377         nlmsvc_release_block(newblock);
 378         nlmsvc_release_block(block);
 379         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 380         return ret;
 381 }
 382
 383 /*
 384  * Test for presence of a conflicting lock.
 385  */
 386 u32
 387 nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
 388                                        struct nlm_lock *conflock)
 389 {
 390         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 391                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
 392                                 file->f_file->f_dentry->d_inode->i_ino,
 393                                 lock->fl.fl_type,
 394                                 (long long)lock->fl.fl_start,
 395                                 (long long)lock->fl.fl_end);
 396
 397         if (posix_test_lock(file->f_file, &lock->fl, &conflock->fl)) {
 398                 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 399                                 conflock->fl.fl_type,
 400                                 (long long)conflock->fl.fl_start,
 401                                 (long long)conflock->fl.fl_end);
 402                 conflock->caller = "somehost";  /* FIXME */
 403                 conflock->oh.len = 0;           /* don't return OH info */
 404                 conflock->svid = conflock->fl.fl_pid;
 405                 return nlm_lck_denied;
 406         }
 407
 408         return nlm_granted;
 409 }
 410
 411 /*
 412  * Remove a lock.
 413  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 414  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 415  * afterwards. In this case the block will still be there, and hence
 416  * must be removed.
 417  */
 418 u32
 419 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
 420 {
 421         int     error;
 422
 423         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 424                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
 425                                 file->f_file->f_dentry->d_inode->i_ino,
 426                                 lock->fl.fl_pid,
 427                                 (long long)lock->fl.fl_start,
 428                                 (long long)lock->fl.fl_end);
 429
 430         /* First, cancel any lock that might be there */
 431         nlmsvc_cancel_blocked(file, lock);
 432
 433         lock->fl.fl_type = F_UNLCK;
 434         error = posix_lock_file(file->f_file, &lock->fl);
 435
 436         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 437 }
 438
 439 /*
 440  * Cancel a previously blocked request.
 441  *
 442  * A cancel request always overrides any grant that may currently
 443  * be in progress.
 444  * The calling procedure must check whether the file can be closed.
 445  */
 446 u32
 447 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
 448 {
 449         struct nlm_block        *block;
 450         int status = 0;
 451
 452         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 453                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
 454                                 file->f_file->f_dentry->d_inode->i_ino,
 455                                 lock->fl.fl_pid,
 456                                 (long long)lock->fl.fl_start,
 457                                 (long long)lock->fl.fl_end);
 458
 459         down(&file->f_sema);
 460         if ((block = nlmsvc_lookup_block(file, lock, 1)) != NULL) {
 461                 status = nlmsvc_unlink_block(block);
 462                 nlmsvc_release_block(block);
 463         }
 464         up(&file->f_sema);
 465         return status ? nlm_lck_denied : nlm_granted;
 466 }
 467
 468 /*
 469  * Unblock a blocked lock request. This is a callback invoked from the
 470  * VFS layer when a lock on which we blocked is removed.
 471  *
 472  * This function doesn't grant the blocked lock instantly, but rather moves
 473  * the block to the head of nlm_blocked where it can be picked up by lockd.
 474  */
 475 static void
 476 nlmsvc_notify_blocked(struct file_lock *fl)
 477 {
 478         struct nlm_block        **bp, *block;
 479
 480         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 481         for (bp = &nlm_blocked; (block = *bp) != 0; bp = &block->b_next) {
 482                 if (nlm_compare_locks(&block->b_call.a_args.lock.fl, fl)) {
 483                         nlmsvc_insert_block(block, 0);
 484                         svc_wake_up(block->b_daemon);
 485                         return;
 486                 }
 487         }
 488
 489         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 490 }
 491
 492 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 493 {
 494         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
 495 }
 496
 497 struct lock_manager_operations nlmsvc_lock_operations = {
 498         .fl_compare_owner = nlmsvc_same_owner,
 499         .fl_notify = nlmsvc_notify_blocked,
 500 };
 501
 502 /*
 503  * Try to claim a lock that was previously blocked.
 504  *
 505  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 506  * RPC thread when notifying the client. This seems like overkill...
 507  * Here's why:
 508  *  -   we don't want to use a synchronous RPC thread, otherwise
 509  *      we might find ourselves hanging on a dead portmapper.
 510  *  -   Some lockd implementations (e.g. HP) don't react to
 511  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 512  */
 513 static void
 514 nlmsvc_grant_blocked(struct nlm_block *block)
 515 {
 516         struct nlm_file         *file = block->b_file;
 517         struct nlm_lock         *lock = &block->b_call.a_args.lock;
 518         int                     error;
 519
 520         dprintk("lockd: grant blocked lock %p\n", block);
 521
 522         /* First thing is lock the file */
 523         down(&file->f_sema);
 524
 525         /* Unlink block request from list */
 526         nlmsvc_unlink_block(block);
 527
 528         /* If b_granted is true this means we've been here before.
 529          * Just retry the grant callback, possibly refreshing the RPC
 530          * binding */
 531         if (block->b_granted) {
 532                 nlm_rebind_host(block->b_host);
 533                 goto callback;
 534         }
 535
 536         /* Try the lock operation again */
 537         lock->fl.fl_flags |= FL_SLEEP;
 538         error = posix_lock_file(file->f_file, &lock->fl);
 539         lock->fl.fl_flags &= ~FL_SLEEP;
 540
 541         switch (error) {
 542         case 0:
 543                 break;
 544         case -EAGAIN:
 545                 dprintk("lockd: lock still blocked\n");
 546                 nlmsvc_insert_block(block, NLM_NEVER);
 547                 goto out_unlock;
 548         default:
 549                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 550                                 -error, __FUNCTION__);
 551                 nlmsvc_insert_block(block, 10 * HZ);
 552                 goto out_unlock;
 553         }
 554
 555 callback:
 556         /* Lock was granted by VFS. */
 557         dprintk("lockd: GRANTing blocked lock.\n");
 558         block->b_granted = 1;
 559
 560         /* Schedule next grant callback in 30 seconds */
 561         nlmsvc_insert_block(block, 30 * HZ);
 562
 563         /* Call the client */
 564         kref_get(&block->b_count);
 565         if (nlmsvc_async_call(&block->b_call, NLMPROC_GRANTED_MSG,
 566                                                 &nlmsvc_grant_ops) < 0)
 567                 nlmsvc_release_block(block);
 568 out_unlock:
 569         up(&file->f_sema);
 570 }
 571
 572 /*
 573  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 574  * RPC call has succeeded or timed out.
 575  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 576  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 577  * chain once more in order to have it removed by lockd itself (which can
 578  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 579  */
 580 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 581 {
 582         struct nlm_rqst         *call = data;
 583         struct nlm_block        *block = container_of(call, struct nlm_block, b_call);
 584         unsigned long           timeout;
 585
 586         dprintk("lockd: GRANT_MSG RPC callback\n");
 587
 588         /* Technically, we should down the file semaphore here. Since we
 589          * move the block towards the head of the queue only, no harm
 590          * can be done, though. */
 591         if (task->tk_status < 0) {
 592                 /* RPC error: Re-insert for retransmission */
 593                 timeout = 10 * HZ;
 594         } else if (block->b_done) {
 595                 /* Block already removed, kill it for real */
 596                 timeout = 0;
 597         } else {
 598                 /* Call was successful, now wait for client callback */
 599                 timeout = 60 * HZ;
 600         }
 601         nlmsvc_insert_block(block, timeout);
 602         svc_wake_up(block->b_daemon);
 603         nlmsvc_release_block(block);
 604 }
 605
 606 static const struct rpc_call_ops nlmsvc_grant_ops = {
 607         .rpc_call_done = nlmsvc_grant_callback,
 608 };
 609
 610 /*
 611  * We received a GRANT_RES callback. Try to find the corresponding
 612  * block.
 613  */
 614 void
 615 nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status)
 616 {
 617         struct nlm_block        *block;
 618         struct nlm_file         *file;
 619
 620         dprintk("grant_reply: looking for cookie %x, host (%08x), s=%d \n",
 621                 *(unsigned int *)(cookie->data),
 622                 ntohl(rqstp->rq_addr.sin_addr.s_addr), status);
 623         if (!(block = nlmsvc_find_block(cookie, &rqstp->rq_addr)))
 624                 return;
 625         file = block->b_file;
 626
 627         file->f_count++;
 628         down(&file->f_sema);
 629         if (block) {
 630                 if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 631                         /* Try again in a couple of seconds */
 632                         nlmsvc_insert_block(block, 10 * HZ);
 633                 } else {
 634                         /* Lock is now held by client, or has been rejected.
 635                          * In both cases, the block should be removed. */
 636                         nlmsvc_unlink_block(block);
 637                 }
 638         }
 639         up(&file->f_sema);
 640         nlm_release_file(file);
 641         nlmsvc_release_block(block);
 642 }
 643
 644 /*
 645  * Retry all blocked locks that have been notified. This is where lockd
 646  * picks up locks that can be granted, or grant notifications that must
 647  * be retransmitted.
 648  */
 649 unsigned long
 650 nlmsvc_retry_blocked(void)
 651 {
 652         struct nlm_block        *block;
 653
 654         dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
 655                         nlm_blocked,
 656                         nlm_blocked? nlm_blocked->b_when : 0);
 657         while ((block = nlm_blocked) != 0) {
 658                 if (block->b_when == NLM_NEVER)
 659                         break;
 660                 if (time_after(block->b_when,jiffies))
 661                         break;
 662                 dprintk("nlmsvc_retry_blocked(%p, when=%ld, done=%d)\n",
 663                         block, block->b_when, block->b_done);
 664                 kref_get(&block->b_count);
 665                 if (block->b_done)
 666                         nlmsvc_unlink_block(block);
 667                 else
 668                         nlmsvc_grant_blocked(block);
 669                 nlmsvc_release_block(block);
 670         }
 671
 672         if ((block = nlm_blocked) && block->b_when != NLM_NEVER)
 673                 return (block->b_when - jiffies);
 674
 675         return MAX_SCHEDULE_TIMEOUT;
 676 }