source3/locking/brlock.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    byte range locking code
   4    Updated to handle range splits/merges.
   5
   6    Copyright (C) Andrew Tridgell 1992-2000
   7    Copyright (C) Jeremy Allison 1992-2000
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 /* This module implements a tdb based byte range locking service,
  25    replacing the fcntl() based byte range locking previously
  26    used. This allows us to provide the same semantics as NT */
  27
  28 #include "includes.h"
  29
  30 #undef DBGC_CLASS
  31 #define DBGC_CLASS DBGC_LOCKING
  32
  33 #define ZERO_ZERO 0
  34
  35 /* This contains elements that differentiate locks. The smbpid is a
  36    client supplied pid, and is essentially the locking context for
  37    this client */
  38
  39 struct lock_context {
  40         uint16 smbpid;
  41         uint16 tid;
  42         struct process_id pid;
  43 };
  44
  45 /* The data in brlock records is an unsorted linear array of these
  46    records.  It is unnecessary to store the count as tdb provides the
  47    size of the record */
  48
  49 struct lock_struct {
  50         struct lock_context context;
  51         br_off start;
  52         br_off size;
  53         int fnum;
  54         enum brl_type lock_type;
  55 };
  56
  57 /* The key used in the brlock database. */
  58
  59 struct lock_key {
  60         SMB_DEV_T device;
  61         SMB_INO_T inode;
  62 };
  63
  64 /* The open brlock.tdb database. */
  65
  66 static TDB_CONTEXT *tdb;
  67
  68 /****************************************************************************
  69  Create a locking key - ensuring zero filled for pad purposes.
  70 ****************************************************************************/
  71
  72 static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode)
  73 {
  74         static struct lock_key key;
  75         TDB_DATA kbuf;
  76
  77         memset(&key, '\0', sizeof(key));
  78         key.device = dev;
  79         key.inode = inode;
  80         kbuf.dptr = (char *)&key;
  81         kbuf.dsize = sizeof(key);
  82         return kbuf;
  83 }
  84
  85 /****************************************************************************
  86  See if two locking contexts are equal.
  87 ****************************************************************************/
  88
  89 static BOOL brl_same_context(struct lock_context *ctx1,
  90                              struct lock_context *ctx2)
  91 {
  92         return (procid_equal(&ctx1->pid, &ctx2->pid) &&
  93                 (ctx1->smbpid == ctx2->smbpid) &&
  94                 (ctx1->tid == ctx2->tid));
  95 }
  96
  97 /****************************************************************************
  98  See if lck1 and lck2 overlap.
  99 ****************************************************************************/
 100
 101 static BOOL brl_overlap(struct lock_struct *lck1,
 102                         struct lock_struct *lck2)
 103 {
 104         /* this extra check is not redundent - it copes with locks
 105            that go beyond the end of 64 bit file space */
 106         if (lck1->size != 0 &&
 107             lck1->start == lck2->start &&
 108             lck1->size == lck2->size) {
 109                 return True;
 110         }
 111
 112         if (lck1->start >= (lck2->start+lck2->size) ||
 113             lck2->start >= (lck1->start+lck1->size)) {
 114                 return False;
 115         }
 116         return True;
 117 }
 118
 119 /****************************************************************************
 120  See if lock2 can be added when lock1 is in place.
 121 ****************************************************************************/
 122
 123 static BOOL brl_conflict(struct lock_struct *lck1,
 124                          struct lock_struct *lck2)
 125 {
 126         if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
 127                 return False;
 128
 129         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
 130                 return False;
 131         }
 132
 133         if (brl_same_context(&lck1->context, &lck2->context) &&
 134             lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
 135                 return False;
 136         }
 137
 138         return brl_overlap(lck1, lck2);
 139 }
 140
 141 #if ZERO_ZERO
 142 static BOOL brl_conflict1(struct lock_struct *lck1,
 143                          struct lock_struct *lck2)
 144 {
 145         if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
 146                 return False;
 147
 148         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
 149                 return False;
 150         }
 151
 152         if (brl_same_context(&lck1->context, &lck2->context) &&
 153             lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
 154                 return False;
 155         }
 156
 157         if (lck2->start == 0 && lck2->size == 0 && lck1->size != 0) {
 158                 return True;
 159         }
 160
 161         if (lck1->start >= (lck2->start + lck2->size) ||
 162             lck2->start >= (lck1->start + lck1->size)) {
 163                 return False;
 164         }
 165
 166         return True;
 167 }
 168 #endif
 169
 170 /****************************************************************************
 171  Check to see if this lock conflicts, but ignore our own locks on the
 172  same fnum only.
 173 ****************************************************************************/
 174
 175 static BOOL brl_conflict_other(struct lock_struct *lck1, struct lock_struct *lck2)
 176 {
 177         if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
 178                 return False;
 179
 180         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK)
 181                 return False;
 182
 183         /*
 184          * Incoming WRITE locks conflict with existing READ locks even
 185          * if the context is the same. JRA. See LOCKTEST7 in smbtorture.
 186          */
 187
 188         if (!(lck2->lock_type == WRITE_LOCK && lck1->lock_type == READ_LOCK)) {
 189                 if (brl_same_context(&lck1->context, &lck2->context) &&
 190                                         lck1->fnum == lck2->fnum)
 191                         return False;
 192         }
 193
 194         return brl_overlap(lck1, lck2);
 195 }
 196
 197 /****************************************************************************
 198  Amazingly enough, w2k3 "remembers" whether the last lock failure
 199  is the same as this one and changes its error code. I wonder if any
 200  app depends on this ?
 201 ****************************************************************************/
 202
 203 static NTSTATUS brl_lock_failed(struct lock_struct *lock)
 204 {
 205         static struct lock_struct last_lock_failure;
 206
 207         if (brl_same_context(&lock->context, &last_lock_failure.context) &&
 208                         lock->fnum == last_lock_failure.fnum &&
 209                         lock->start == last_lock_failure.start &&
 210                         lock->size == last_lock_failure.size) {
 211                 return NT_STATUS_FILE_LOCK_CONFLICT;
 212         }
 213         last_lock_failure = *lock;
 214         if (lock->start >= 0xEF000000 &&
 215                         (lock->start >> 63) == 0) {
 216                 /* amazing the little things you learn with a test
 217                    suite. Locks beyond this offset (as a 64 bit
 218                    number!) always generate the conflict error code,
 219                    unless the top bit is set */
 220                 return NT_STATUS_FILE_LOCK_CONFLICT;
 221         }
 222         return NT_STATUS_LOCK_NOT_GRANTED;
 223 }
 224
 225 #if DONT_DO_THIS
 226         /* doing this traversal could kill solaris machines under high load (tridge) */
 227         /* delete any dead locks */
 228
 229 /****************************************************************************
 230  Delete a record if it is for a dead process, if check_self is true, then
 231  delete any records belonging to this pid also (there shouldn't be any).
 232 ****************************************************************************/
 233
 234 static int delete_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
 235 {
 236         struct lock_struct *locks;
 237         int count, i;
 238         BOOL check_self = *(BOOL *)state;
 239         pid_t mypid = sys_getpid();
 240
 241         tdb_chainlock(tdb, kbuf);
 242
 243         locks = (struct lock_struct *)dbuf.dptr;
 244
 245         count = dbuf.dsize / sizeof(*locks);
 246         for (i=0; i<count; i++) {
 247                 struct lock_struct *lock = &locks[i];
 248
 249                 /* If check_self is true we want to remove our own records. */
 250                 if (check_self && (mypid == lock->context.pid)) {
 251
 252                         DEBUG(0,("brlock : delete_fn. LOGIC ERROR ! Shutting down and a record for my pid (%u) exists !\n",
 253                                         (unsigned int)lock->context.pid ));
 254
 255                 } else if (process_exists(&lock->context.pid)) {
 256
 257                         DEBUG(10,("brlock : delete_fn. pid %u exists.\n", (unsigned int)lock->context.pid ));
 258                         continue;
 259                 }
 260
 261                 DEBUG(10,("brlock : delete_fn. Deleting record for process %u\n",
 262                                 (unsigned int)lock->context.pid ));
 263
 264                 if (count > 1 && i < count-1) {
 265                         memmove(&locks[i], &locks[i+1],
 266                                 sizeof(*locks)*((count-1) - i));
 267                 }
 268                 count--;
 269                 i--;
 270         }
 271
 272         if (count == 0) {
 273                 tdb_delete(tdb, kbuf);
 274         } else if (count < (dbuf.dsize / sizeof(*locks))) {
 275                 dbuf.dsize = count * sizeof(*locks);
 276                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 277         }
 278
 279         tdb_chainunlock(tdb, kbuf);
 280         return 0;
 281 }
 282 #endif
 283
 284 /****************************************************************************
 285  Open up the brlock.tdb database.
 286 ****************************************************************************/
 287
 288 void brl_init(int read_only)
 289 {
 290         if (tdb)
 291                 return;
 292         tdb = tdb_open_log(lock_path("brlock.tdb"), 0,  TDB_DEFAULT|(read_only?0x0:TDB_CLEAR_IF_FIRST),
 293                        read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644 );
 294         if (!tdb) {
 295                 DEBUG(0,("Failed to open byte range locking database\n"));
 296                 return;
 297         }
 298
 299 #if DONT_DO_THIS
 300         /* doing this traversal could kill solaris machines under high load (tridge) */
 301         /* delete any dead locks */
 302         if (!read_only) {
 303                 BOOL check_self = False;
 304                 tdb_traverse(tdb, delete_fn, &check_self);
 305         }
 306 #endif
 307 }
 308
 309 /****************************************************************************
 310  Close down the brlock.tdb database.
 311 ****************************************************************************/
 312
 313 void brl_shutdown(int read_only)
 314 {
 315         if (!tdb)
 316                 return;
 317
 318 #if DONT_DO_THIS
 319         /* doing this traversal could kill solaris machines under high load (tridge) */
 320         /* delete any dead locks */
 321         if (!read_only) {
 322                 BOOL check_self = True;
 323                 tdb_traverse(tdb, delete_fn, &check_self);
 324         }
 325 #endif
 326
 327         tdb_close(tdb);
 328 }
 329
 330 #if ZERO_ZERO
 331 /****************************************************************************
 332 compare two locks for sorting
 333 ****************************************************************************/
 334 static int lock_compare(struct lock_struct *lck1,
 335                          struct lock_struct *lck2)
 336 {
 337         if (lck1->start != lck2->start) return (lck1->start - lck2->start);
 338         if (lck2->size != lck1->size) {
 339                 return ((int)lck1->size - (int)lck2->size);
 340         }
 341         return 0;
 342 }
 343 #endif
 344
 345 /****************************************************************************
 346  Lock a range of bytes.
 347 ****************************************************************************/
 348
 349 NTSTATUS brl_lock(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 350                   uint16 smbpid, struct process_id pid, uint16 tid,
 351                   br_off start, br_off size,
 352                   enum brl_type lock_type, BOOL *my_lock_ctx)
 353 {
 354         TDB_DATA kbuf, dbuf;
 355         int count, i;
 356         struct lock_struct lock, *locks;
 357         char *tp;
 358         NTSTATUS status = NT_STATUS_OK;
 359
 360         *my_lock_ctx = False;
 361         kbuf = locking_key(dev,ino);
 362
 363         dbuf.dptr = NULL;
 364
 365 #if !ZERO_ZERO
 366         if (start == 0 && size == 0) {
 367                 DEBUG(0,("client sent 0/0 lock - please report this\n"));
 368         }
 369 #endif
 370
 371         tdb_chainlock(tdb, kbuf);
 372         dbuf = tdb_fetch(tdb, kbuf);
 373
 374         lock.context.smbpid = smbpid;
 375         lock.context.pid = pid;
 376         lock.context.tid = tid;
 377         lock.start = start;
 378         lock.size = size;
 379         lock.fnum = fnum;
 380         lock.lock_type = lock_type;
 381
 382         if (dbuf.dptr) {
 383                 /* there are existing locks - make sure they don't conflict */
 384                 locks = (struct lock_struct *)dbuf.dptr;
 385                 count = dbuf.dsize / sizeof(*locks);
 386                 for (i=0; i<count; i++) {
 387                         if (brl_conflict(&locks[i], &lock)) {
 388                                 status = brl_lock_failed(&lock);;
 389                                 /* Did we block ourselves ? */
 390                                 if (brl_same_context(&locks[i].context, &lock.context))
 391                                         *my_lock_ctx = True;
 392                                 goto fail;
 393                         }
 394 #if ZERO_ZERO
 395                         if (lock.start == 0 && lock.size == 0 &&
 396                             locks[i].size == 0) {
 397                                 break;
 398                         }
 399 #endif
 400                 }
 401         }
 402
 403         /* no conflicts - add it to the list of locks */
 404         tp = SMB_REALLOC(dbuf.dptr, dbuf.dsize + sizeof(*locks));
 405         if (!tp) {
 406                 status = NT_STATUS_NO_MEMORY;
 407                 goto fail;
 408         } else {
 409                 dbuf.dptr = tp;
 410         }
 411         memcpy(dbuf.dptr + dbuf.dsize, &lock, sizeof(lock));
 412         dbuf.dsize += sizeof(lock);
 413
 414 #if ZERO_ZERO
 415         /* sort the lock list */
 416         qsort(dbuf.dptr, dbuf.dsize/sizeof(lock), sizeof(lock), lock_compare);
 417 #endif
 418
 419         if (tdb_store(tdb, kbuf, dbuf, TDB_REPLACE) != 0) {
 420                 status = NT_STATUS_INTERNAL_DB_CORRUPTION;
 421                 goto fail;
 422         }
 423
 424         SAFE_FREE(dbuf.dptr);
 425         tdb_chainunlock(tdb, kbuf);
 426         return NT_STATUS_OK;
 427
 428  fail:
 429
 430         SAFE_FREE(dbuf.dptr);
 431         tdb_chainunlock(tdb, kbuf);
 432         return status;
 433 }
 434
 435 /****************************************************************************
 436  Check if an unlock overlaps a pending lock.
 437 ****************************************************************************/
 438
 439 static BOOL brl_pending_overlap(struct lock_struct *lock, struct lock_struct *pend_lock)
 440 {
 441         if ((lock->start <= pend_lock->start) && (lock->start + lock->size > pend_lock->start))
 442                 return True;
 443         if ((lock->start >= pend_lock->start) && (lock->start <= pend_lock->start + pend_lock->size))
 444                 return True;
 445         return False;
 446 }
 447
 448 /****************************************************************************
 449  Unlock a range of bytes.
 450 ****************************************************************************/
 451
 452 BOOL brl_unlock(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 453                 uint16 smbpid, struct process_id pid, uint16 tid,
 454                 br_off start, br_off size,
 455                 BOOL remove_pending_locks_only,
 456                 void (*pre_unlock_fn)(void *),
 457                 void *pre_unlock_data)
 458 {
 459         TDB_DATA kbuf, dbuf;
 460         int count, i, j;
 461         struct lock_struct *locks;
 462         struct lock_context context;
 463
 464         kbuf = locking_key(dev,ino);
 465
 466         dbuf.dptr = NULL;
 467
 468         tdb_chainlock(tdb, kbuf);
 469         dbuf = tdb_fetch(tdb, kbuf);
 470
 471         if (!dbuf.dptr) {
 472                 DEBUG(10,("brl_unlock: tdb_fetch failed !\n"));
 473                 goto fail;
 474         }
 475
 476         context.smbpid = smbpid;
 477         context.pid = pid;
 478         context.tid = tid;
 479
 480         /* there are existing locks - find a match */
 481         locks = (struct lock_struct *)dbuf.dptr;
 482         count = dbuf.dsize / sizeof(*locks);
 483
 484 #if ZERO_ZERO
 485         for (i=0; i<count; i++) {
 486                 struct lock_struct *lock = &locks[i];
 487
 488                 if (lock->lock_type == WRITE_LOCK &&
 489                     brl_same_context(&lock->context, &context) &&
 490                     lock->fnum == fnum &&
 491                     lock->start == start &&
 492                     lock->size == size) {
 493
 494                         if (pre_unlock_fn)
 495                                 (*pre_unlock_fn)(pre_unlock_data);
 496
 497                         /* found it - delete it */
 498                         if (count == 1) {
 499                                 tdb_delete(tdb, kbuf);
 500                         } else {
 501                                 if (i < count-1) {
 502                                         memmove(&locks[i], &locks[i+1],
 503                                                 sizeof(*locks)*((count-1) - i));
 504                                 }
 505                                 dbuf.dsize -= sizeof(*locks);
 506                                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 507                         }
 508
 509                         SAFE_FREE(dbuf.dptr);
 510                         tdb_chainunlock(tdb, kbuf);
 511                         return True;
 512                 }
 513         }
 514 #endif
 515
 516         locks = (struct lock_struct *)dbuf.dptr;
 517         count = dbuf.dsize / sizeof(*locks);
 518         for (i=0; i<count; i++) {
 519                 struct lock_struct *lock = &locks[i];
 520
 521                 if (brl_same_context(&lock->context, &context) &&
 522                                 lock->fnum == fnum &&
 523                                 lock->start == start &&
 524                                 lock->size == size) {
 525
 526                         if (remove_pending_locks_only && lock->lock_type != PENDING_LOCK)
 527                                 continue;
 528
 529                         if (lock->lock_type != PENDING_LOCK) {
 530
 531                                 /* Do any POSIX unlocks needed. */
 532                                 if (pre_unlock_fn)
 533                                         (*pre_unlock_fn)(pre_unlock_data);
 534
 535                                 /* Send unlock messages to any pending waiters that overlap. */
 536                                 for (j=0; j<count; j++) {
 537                                         struct lock_struct *pend_lock = &locks[j];
 538
 539                                         /* Ignore non-pending locks. */
 540                                         if (pend_lock->lock_type != PENDING_LOCK)
 541                                                 continue;
 542
 543                                         /* We could send specific lock info here... */
 544                                         if (brl_pending_overlap(lock, pend_lock)) {
 545                                                 DEBUG(10,("brl_unlock: sending unlock message to pid %s\n",
 546                                                                         procid_str_static(&pend_lock->context.pid )));
 547
 548                                                 message_send_pid(pend_lock->context.pid,
 549                                                                 MSG_SMB_UNLOCK,
 550                                                                 NULL, 0, True);
 551                                         }
 552                                 }
 553                         }
 554
 555                         /* found it - delete it */
 556                         if (count == 1) {
 557                                 tdb_delete(tdb, kbuf);
 558                         } else {
 559                                 if (i < count-1) {
 560                                         memmove(&locks[i], &locks[i+1],
 561                                                 sizeof(*locks)*((count-1) - i));
 562                                 }
 563                                 dbuf.dsize -= sizeof(*locks);
 564                                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 565                         }
 566
 567                         SAFE_FREE(dbuf.dptr);
 568                         tdb_chainunlock(tdb, kbuf);
 569                         return True;
 570                 }
 571         }
 572
 573         /* we didn't find it */
 574
 575  fail:
 576         SAFE_FREE(dbuf.dptr);
 577         tdb_chainunlock(tdb, kbuf);
 578         return False;
 579 }
 580
 581
 582 /****************************************************************************
 583  Test if we could add a lock if we wanted to.
 584 ****************************************************************************/
 585
 586 BOOL brl_locktest(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 587                   uint16 smbpid, struct process_id pid, uint16 tid,
 588                   br_off start, br_off size,
 589                   enum brl_type lock_type)
 590 {
 591         TDB_DATA kbuf, dbuf;
 592         int count, i;
 593         struct lock_struct lock, *locks;
 594
 595         kbuf = locking_key(dev,ino);
 596
 597         dbuf.dptr = NULL;
 598
 599         dbuf = tdb_fetch(tdb, kbuf);
 600
 601         lock.context.smbpid = smbpid;
 602         lock.context.pid = pid;
 603         lock.context.tid = tid;
 604         lock.start = start;
 605         lock.size = size;
 606         lock.fnum = fnum;
 607         lock.lock_type = lock_type;
 608
 609         if (dbuf.dptr) {
 610                 /* there are existing locks - make sure they don't conflict */
 611                 locks = (struct lock_struct *)dbuf.dptr;
 612                 count = dbuf.dsize / sizeof(*locks);
 613                 for (i=0; i<count; i++) {
 614                         /*
 615                          * Our own locks don't conflict.
 616                          */
 617                         if (brl_conflict_other(&locks[i], &lock))
 618                                 goto fail;
 619                 }
 620         }
 621
 622         /* no conflicts - we could have added it */
 623         SAFE_FREE(dbuf.dptr);
 624         return True;
 625
 626  fail:
 627         SAFE_FREE(dbuf.dptr);
 628         return False;
 629 }
 630
 631 /****************************************************************************
 632  Remove any locks associated with a open file.
 633 ****************************************************************************/
 634
 635 void brl_close(SMB_DEV_T dev, SMB_INO_T ino, struct process_id pid, int tid, int fnum)
 636 {
 637         TDB_DATA kbuf, dbuf;
 638         int count, i, j, dcount=0;
 639         struct lock_struct *locks;
 640
 641         kbuf = locking_key(dev,ino);
 642
 643         dbuf.dptr = NULL;
 644
 645         tdb_chainlock(tdb, kbuf);
 646         dbuf = tdb_fetch(tdb, kbuf);
 647
 648         if (!dbuf.dptr) goto fail;
 649
 650         /* there are existing locks - remove any for this fnum */
 651         locks = (struct lock_struct *)dbuf.dptr;
 652         count = dbuf.dsize / sizeof(*locks);
 653
 654         for (i=0; i<count; i++) {
 655                 struct lock_struct *lock = &locks[i];
 656
 657                 if (lock->context.tid == tid &&
 658                     procid_equal(&lock->context.pid, &pid) &&
 659                     lock->fnum == fnum) {
 660
 661                         /* Send unlock messages to any pending waiters that overlap. */
 662                         for (j=0; j<count; j++) {
 663                                 struct lock_struct *pend_lock = &locks[j];
 664
 665                                 /* Ignore our own or non-pending locks. */
 666                                 if (pend_lock->lock_type != PENDING_LOCK)
 667                                         continue;
 668
 669                                 if (pend_lock->context.tid == tid &&
 670                                     procid_equal(&pend_lock->context.pid, &pid) &&
 671                                     pend_lock->fnum == fnum)
 672                                         continue;
 673
 674                                 /* We could send specific lock info here... */
 675                                 if (brl_pending_overlap(lock, pend_lock))
 676                                         message_send_pid(pend_lock->context.pid,
 677                                                         MSG_SMB_UNLOCK,
 678                                                         NULL, 0, True);
 679                         }
 680
 681                         /* found it - delete it */
 682                         if (count > 1 && i < count-1) {
 683                                 memmove(&locks[i], &locks[i+1],
 684                                         sizeof(*locks)*((count-1) - i));
 685                         }
 686                         count--;
 687                         i--;
 688                         dcount++;
 689                 }
 690         }
 691
 692         if (count == 0) {
 693                 tdb_delete(tdb, kbuf);
 694         } else if (count < (dbuf.dsize / sizeof(*locks))) {
 695                 dbuf.dsize -= dcount * sizeof(*locks);
 696                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 697         }
 698
 699         /* we didn't find it */
 700  fail:
 701         SAFE_FREE(dbuf.dptr);
 702         tdb_chainunlock(tdb, kbuf);
 703 }
 704
 705 /****************************************************************************
 706  Traverse the whole database with this function, calling traverse_callback
 707  on each lock.
 708 ****************************************************************************/
 709
 710 static int traverse_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
 711 {
 712         struct lock_struct *locks;
 713         struct lock_key *key;
 714         int i;
 715
 716         BRLOCK_FN(traverse_callback) = (BRLOCK_FN_CAST())state;
 717
 718         locks = (struct lock_struct *)dbuf.dptr;
 719         key = (struct lock_key *)kbuf.dptr;
 720
 721         for (i=0;i<dbuf.dsize/sizeof(*locks);i++) {
 722                 traverse_callback(key->device, key->inode,
 723                                   locks[i].context.pid,
 724                                   locks[i].lock_type,
 725                                   locks[i].start,
 726                                   locks[i].size);
 727         }
 728         return 0;
 729 }
 730
 731 /*******************************************************************
 732  Call the specified function on each lock in the database.
 733 ********************************************************************/
 734
 735 int brl_forall(BRLOCK_FN(fn))
 736 {
 737         if (!tdb) return 0;
 738         return tdb_traverse(tdb, traverse_fn, (void *)fn);
 739 }