source/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 #define ZERO_ZERO 0
  31
  32 /* This contains elements that differentiate locks. The smbpid is a
  33    client supplied pid, and is essentially the locking context for
  34    this client */
  35
  36 struct lock_context {
  37         uint16 smbpid;
  38         uint16 tid;
  39         pid_t pid;
  40 };
  41
  42 /* The data in brlock records is an unsorted linear array of these
  43    records.  It is unnecessary to store the count as tdb provides the
  44    size of the record */
  45
  46 struct lock_struct {
  47         struct lock_context context;
  48         br_off start;
  49         br_off size;
  50         int fnum;
  51         enum brl_type lock_type;
  52 };
  53
  54 /* The key used in the brlock database. */
  55
  56 struct lock_key {
  57         SMB_DEV_T device;
  58         SMB_INO_T inode;
  59 };
  60
  61 /* The open brlock.tdb database. */
  62
  63 static TDB_CONTEXT *tdb;
  64
  65 /****************************************************************************
  66  Create a locking key - ensuring zero filled for pad purposes.
  67 ****************************************************************************/
  68
  69 static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode)
  70 {
  71         static struct lock_key key;
  72         TDB_DATA kbuf;
  73
  74         memset(&key, '\0', sizeof(key));
  75         key.device = dev;
  76         key.inode = inode;
  77         kbuf.dptr = (char *)&key;
  78         kbuf.dsize = sizeof(key);
  79         return kbuf;
  80 }
  81
  82 /****************************************************************************
  83  See if two locking contexts are equal.
  84 ****************************************************************************/
  85
  86 static BOOL brl_same_context(struct lock_context *ctx1,
  87                              struct lock_context *ctx2)
  88 {
  89         return (ctx1->pid == ctx2->pid) &&
  90                 (ctx1->smbpid == ctx2->smbpid) &&
  91                 (ctx1->tid == ctx2->tid);
  92 }
  93
  94 /****************************************************************************
  95  See if lock2 can be added when lock1 is in place.
  96 ****************************************************************************/
  97
  98 static BOOL brl_conflict(struct lock_struct *lck1,
  99                          struct lock_struct *lck2)
 100 {
 101         if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
 102                 return False;
 103
 104         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
 105                 return False;
 106         }
 107
 108         if (brl_same_context(&lck1->context, &lck2->context) &&
 109             lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
 110                 return False;
 111         }
 112
 113         if (lck1->start >= (lck2->start + lck2->size) ||
 114             lck2->start >= (lck1->start + lck1->size)) {
 115                 return False;
 116         }
 117
 118         return True;
 119 }
 120
 121 #if ZERO_ZERO
 122 static BOOL brl_conflict1(struct lock_struct *lck1,
 123                          struct lock_struct *lck2)
 124 {
 125         if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
 126                 return False;
 127
 128         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
 129                 return False;
 130         }
 131
 132         if (brl_same_context(&lck1->context, &lck2->context) &&
 133             lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
 134                 return False;
 135         }
 136
 137         if (lck2->start == 0 && lck2->size == 0 && lck1->size != 0) {
 138                 return True;
 139         }
 140
 141         if (lck1->start >= (lck2->start + lck2->size) ||
 142             lck2->start >= (lck1->start + lck1->size)) {
 143                 return False;
 144         }
 145
 146         return True;
 147 }
 148 #endif
 149
 150 /****************************************************************************
 151  Check to see if this lock conflicts, but ignore our own locks on the
 152  same fnum only.
 153 ****************************************************************************/
 154
 155 static BOOL brl_conflict_other(struct lock_struct *lck1, struct lock_struct *lck2)
 156 {
 157         if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
 158                 return False;
 159
 160         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK)
 161                 return False;
 162
 163         /*
 164          * Incoming WRITE locks conflict with existing READ locks even
 165          * if the context is the same. JRA. See LOCKTEST7 in smbtorture.
 166          */
 167
 168         if (!(lck2->lock_type == WRITE_LOCK && lck1->lock_type == READ_LOCK)) {
 169                 if (brl_same_context(&lck1->context, &lck2->context) &&
 170                                         lck1->fnum == lck2->fnum)
 171                         return False;
 172         }
 173
 174         if (lck1->start >= (lck2->start + lck2->size) ||
 175             lck2->start >= (lck1->start + lck1->size)) return False;
 176
 177         return True;
 178 }
 179
 180
 181 #if DONT_DO_THIS
 182         /* doing this traversal could kill solaris machines under high load (tridge) */
 183         /* delete any dead locks */
 184
 185 /****************************************************************************
 186  Delete a record if it is for a dead process, if check_self is true, then
 187  delete any records belonging to this pid also (there shouldn't be any).
 188 ****************************************************************************/
 189
 190 static int delete_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
 191 {
 192         struct lock_struct *locks;
 193         int count, i;
 194         BOOL check_self = *(BOOL *)state;
 195         pid_t mypid = sys_getpid();
 196
 197         tdb_chainlock(tdb, kbuf);
 198
 199         locks = (struct lock_struct *)dbuf.dptr;
 200
 201         count = dbuf.dsize / sizeof(*locks);
 202         for (i=0; i<count; i++) {
 203                 struct lock_struct *lock = &locks[i];
 204
 205                 /* If check_self is true we want to remove our own records. */
 206                 if (check_self && (mypid == lock->context.pid)) {
 207
 208                         DEBUG(0,("brlock : delete_fn. LOGIC ERROR ! Shutting down and a record for my pid (%u) exists !\n",
 209                                         (unsigned int)lock->context.pid ));
 210
 211                 } else if (process_exists(lock->context.pid)) {
 212
 213                         DEBUG(10,("brlock : delete_fn. pid %u exists.\n", (unsigned int)lock->context.pid ));
 214                         continue;
 215                 }
 216
 217                 DEBUG(10,("brlock : delete_fn. Deleting record for process %u\n",
 218                                 (unsigned int)lock->context.pid ));
 219
 220                 if (count > 1 && i < count-1) {
 221                         memmove(&locks[i], &locks[i+1],
 222                                 sizeof(*locks)*((count-1) - i));
 223                 }
 224                 count--;
 225                 i--;
 226         }
 227
 228         if (count == 0) {
 229                 tdb_delete(tdb, kbuf);
 230         } else if (count < (dbuf.dsize / sizeof(*locks))) {
 231                 dbuf.dsize = count * sizeof(*locks);
 232                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 233         }
 234
 235         tdb_chainunlock(tdb, kbuf);
 236         return 0;
 237 }
 238 #endif
 239
 240 /****************************************************************************
 241  Open up the brlock.tdb database.
 242 ****************************************************************************/
 243
 244 void brl_init(int read_only)
 245 {
 246         if (tdb)
 247                 return;
 248         tdb = tdb_open_log(lock_path("brlock.tdb"), 0,  TDB_DEFAULT|(read_only?0x0:TDB_CLEAR_IF_FIRST),
 249                        read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644);
 250         if (!tdb) {
 251                 DEBUG(0,("Failed to open byte range locking database\n"));
 252                 return;
 253         }
 254
 255 #if DONT_DO_THIS
 256         /* doing this traversal could kill solaris machines under high load (tridge) */
 257         /* delete any dead locks */
 258         if (!read_only) {
 259                 BOOL check_self = False;
 260                 tdb_traverse(tdb, delete_fn, &check_self);
 261         }
 262 #endif
 263 }
 264
 265 /****************************************************************************
 266  Close down the brlock.tdb database.
 267 ****************************************************************************/
 268
 269 void brl_shutdown(int read_only)
 270 {
 271         if (!tdb)
 272                 return;
 273
 274 #if DONT_DO_THIS
 275         /* doing this traversal could kill solaris machines under high load (tridge) */
 276         /* delete any dead locks */
 277         if (!read_only) {
 278                 BOOL check_self = True;
 279                 tdb_traverse(tdb, delete_fn, &check_self);
 280         }
 281 #endif
 282
 283         tdb_close(tdb);
 284 }
 285
 286 #if ZERO_ZERO
 287 /****************************************************************************
 288 compare two locks for sorting
 289 ****************************************************************************/
 290 static int lock_compare(struct lock_struct *lck1,
 291                          struct lock_struct *lck2)
 292 {
 293         if (lck1->start != lck2->start) return (lck1->start - lck2->start);
 294         if (lck2->size != lck1->size) {
 295                 return ((int)lck1->size - (int)lck2->size);
 296         }
 297         return 0;
 298 }
 299 #endif
 300
 301 /****************************************************************************
 302  Lock a range of bytes.
 303 ****************************************************************************/
 304
 305 NTSTATUS brl_lock(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 306                   uint16 smbpid, pid_t pid, uint16 tid,
 307                   br_off start, br_off size,
 308                   enum brl_type lock_type)
 309 {
 310         TDB_DATA kbuf, dbuf;
 311         int count, i;
 312         struct lock_struct lock, *locks;
 313         char *tp;
 314         NTSTATUS status = NT_STATUS_OK;
 315         static int last_failed = -1;
 316         static br_off last_failed_start;
 317
 318         kbuf = locking_key(dev,ino);
 319
 320         dbuf.dptr = NULL;
 321
 322 #if !ZERO_ZERO
 323         if (start == 0 && size == 0) {
 324                 DEBUG(0,("client sent 0/0 lock - please report this\n"));
 325         }
 326 #endif
 327
 328         tdb_chainlock(tdb, kbuf);
 329         dbuf = tdb_fetch(tdb, kbuf);
 330
 331         lock.context.smbpid = smbpid;
 332         lock.context.pid = pid;
 333         lock.context.tid = tid;
 334         lock.start = start;
 335         lock.size = size;
 336         lock.fnum = fnum;
 337         lock.lock_type = lock_type;
 338
 339         if (dbuf.dptr) {
 340                 /* there are existing locks - make sure they don't conflict */
 341                 locks = (struct lock_struct *)dbuf.dptr;
 342                 count = dbuf.dsize / sizeof(*locks);
 343                 for (i=0; i<count; i++) {
 344                         if (brl_conflict(&locks[i], &lock)) {
 345                                 status = NT_STATUS_LOCK_NOT_GRANTED;
 346                                 goto fail;
 347                         }
 348 #if ZERO_ZERO
 349                         if (lock.start == 0 && lock.size == 0 &&
 350                             locks[i].size == 0) {
 351                                 break;
 352                         }
 353 #endif
 354                 }
 355         }
 356
 357         /* no conflicts - add it to the list of locks */
 358         tp = Realloc(dbuf.dptr, dbuf.dsize + sizeof(*locks));
 359         if (!tp) {
 360                 status = NT_STATUS_NO_MEMORY;
 361                 goto fail;
 362         } else {
 363                 dbuf.dptr = tp;
 364         }
 365         memcpy(dbuf.dptr + dbuf.dsize, &lock, sizeof(lock));
 366         dbuf.dsize += sizeof(lock);
 367
 368 #if ZERO_ZERO
 369         /* sort the lock list */
 370         qsort(dbuf.dptr, dbuf.dsize/sizeof(lock), sizeof(lock), lock_compare);
 371 #endif
 372
 373         tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 374
 375         SAFE_FREE(dbuf.dptr);
 376         tdb_chainunlock(tdb, kbuf);
 377         return NT_STATUS_OK;
 378
 379  fail:
 380         /* this is a nasty hack to try to simulate the lock result cache code in w2k.
 381            It isn't completely accurate as I haven't yet worked out the correct
 382            semantics (tridge)
 383         */
 384         if (last_failed == fnum &&
 385             last_failed_start == start &&
 386             NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 387                 status = NT_STATUS_FILE_LOCK_CONFLICT;
 388         }
 389         last_failed = fnum;
 390         last_failed_start = start;
 391
 392         SAFE_FREE(dbuf.dptr);
 393         tdb_chainunlock(tdb, kbuf);
 394         return status;
 395 }
 396
 397 /****************************************************************************
 398  Check if an unlock overlaps a pending lock.
 399 ****************************************************************************/
 400
 401 static BOOL brl_pending_overlap(struct lock_struct *lock, struct lock_struct *pend_lock)
 402 {
 403         if ((lock->start <= pend_lock->start) && (lock->start + lock->size > pend_lock->start))
 404                 return True;
 405         if ((lock->start >= pend_lock->start) && (lock->start <= pend_lock->start + pend_lock->size))
 406                 return True;
 407         return False;
 408 }
 409
 410 /****************************************************************************
 411  Unlock a range of bytes.
 412 ****************************************************************************/
 413
 414 BOOL brl_unlock(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 415                 uint16 smbpid, pid_t pid, uint16 tid,
 416                 br_off start, br_off size,
 417                 BOOL remove_pending_locks_only)
 418 {
 419         TDB_DATA kbuf, dbuf;
 420         int count, i, j;
 421         struct lock_struct *locks;
 422         struct lock_context context;
 423
 424         kbuf = locking_key(dev,ino);
 425
 426         dbuf.dptr = NULL;
 427
 428         tdb_chainlock(tdb, kbuf);
 429         dbuf = tdb_fetch(tdb, kbuf);
 430
 431         if (!dbuf.dptr) {
 432                 DEBUG(10,("brl_unlock: tdb_fetch failed !\n"));
 433                 goto fail;
 434         }
 435
 436         context.smbpid = smbpid;
 437         context.pid = pid;
 438         context.tid = tid;
 439
 440         /* there are existing locks - find a match */
 441         locks = (struct lock_struct *)dbuf.dptr;
 442         count = dbuf.dsize / sizeof(*locks);
 443
 444 #if ZERO_ZERO
 445         for (i=0; i<count; i++) {
 446                 struct lock_struct *lock = &locks[i];
 447
 448                 if (lock->lock_type == WRITE_LOCK &&
 449                     brl_same_context(&lock->context, &context) &&
 450                     lock->fnum == fnum &&
 451                     lock->start == start &&
 452                     lock->size == size) {
 453                         /* found it - delete it */
 454                         if (count == 1) {
 455                                 tdb_delete(tdb, kbuf);
 456                         } else {
 457                                 if (i < count-1) {
 458                                         memmove(&locks[i], &locks[i+1],
 459                                                 sizeof(*locks)*((count-1) - i));
 460                                 }
 461                                 dbuf.dsize -= sizeof(*locks);
 462                                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 463                         }
 464
 465                         SAFE_FREE(dbuf.dptr);
 466                         tdb_chainunlock(tdb, kbuf);
 467                         return True;
 468                 }
 469         }
 470 #endif
 471
 472         locks = (struct lock_struct *)dbuf.dptr;
 473         count = dbuf.dsize / sizeof(*locks);
 474         for (i=0; i<count; i++) {
 475                 struct lock_struct *lock = &locks[i];
 476
 477                 if (brl_same_context(&lock->context, &context) &&
 478                                 lock->fnum == fnum &&
 479                                 lock->start == start &&
 480                                 lock->size == size) {
 481
 482                         if (remove_pending_locks_only && lock->lock_type != PENDING_LOCK)
 483                                 continue;
 484
 485                         if (lock->lock_type != PENDING_LOCK) {
 486                                 /* Send unlock messages to any pending waiters that overlap. */
 487                                 for (j=0; j<count; j++) {
 488                                         struct lock_struct *pend_lock = &locks[j];
 489
 490                                         /* Ignore non-pending locks. */
 491                                         if (pend_lock->lock_type != PENDING_LOCK)
 492                                                 continue;
 493
 494                                         /* We could send specific lock info here... */
 495                                         if (brl_pending_overlap(lock, pend_lock)) {
 496                                                 DEBUG(10,("brl_unlock: sending unlock message to pid %u\n",
 497                                                                         (unsigned int)pend_lock->context.pid ));
 498
 499                                                 message_send_pid(pend_lock->context.pid,
 500                                                                 MSG_SMB_UNLOCK,
 501                                                                 NULL, 0, True);
 502                                         }
 503                                 }
 504                         }
 505
 506                         /* found it - delete it */
 507                         if (count == 1) {
 508                                 tdb_delete(tdb, kbuf);
 509                         } else {
 510                                 if (i < count-1) {
 511                                         memmove(&locks[i], &locks[i+1],
 512                                                 sizeof(*locks)*((count-1) - i));
 513                                 }
 514                                 dbuf.dsize -= sizeof(*locks);
 515                                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 516                         }
 517
 518                         SAFE_FREE(dbuf.dptr);
 519                         tdb_chainunlock(tdb, kbuf);
 520                         return True;
 521                 }
 522         }
 523
 524         /* we didn't find it */
 525
 526  fail:
 527         SAFE_FREE(dbuf.dptr);
 528         tdb_chainunlock(tdb, kbuf);
 529         return False;
 530 }
 531
 532
 533 /****************************************************************************
 534  Test if we could add a lock if we wanted to.
 535 ****************************************************************************/
 536
 537 BOOL brl_locktest(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 538                   uint16 smbpid, pid_t pid, uint16 tid,
 539                   br_off start, br_off size,
 540                   enum brl_type lock_type, int check_self)
 541 {
 542         TDB_DATA kbuf, dbuf;
 543         int count, i;
 544         struct lock_struct lock, *locks;
 545
 546         kbuf = locking_key(dev,ino);
 547
 548         dbuf.dptr = NULL;
 549
 550         tdb_chainlock(tdb, kbuf);
 551         dbuf = tdb_fetch(tdb, kbuf);
 552
 553         lock.context.smbpid = smbpid;
 554         lock.context.pid = pid;
 555         lock.context.tid = tid;
 556         lock.start = start;
 557         lock.size = size;
 558         lock.fnum = fnum;
 559         lock.lock_type = lock_type;
 560
 561         if (dbuf.dptr) {
 562                 /* there are existing locks - make sure they don't conflict */
 563                 locks = (struct lock_struct *)dbuf.dptr;
 564                 count = dbuf.dsize / sizeof(*locks);
 565                 for (i=0; i<count; i++) {
 566                         if (check_self) {
 567                                 if (brl_conflict(&locks[i], &lock))
 568                                         goto fail;
 569                         } else {
 570                                 /*
 571                                  * Our own locks don't conflict.
 572                                  */
 573                                 if (brl_conflict_other(&locks[i], &lock))
 574                                         goto fail;
 575                         }
 576                 }
 577         }
 578
 579         /* no conflicts - we could have added it */
 580         SAFE_FREE(dbuf.dptr);
 581         tdb_chainunlock(tdb, kbuf);
 582         return True;
 583
 584  fail:
 585         SAFE_FREE(dbuf.dptr);
 586         tdb_chainunlock(tdb, kbuf);
 587         return False;
 588 }
 589
 590 /****************************************************************************
 591  Remove any locks associated with a open file.
 592 ****************************************************************************/
 593
 594 void brl_close(SMB_DEV_T dev, SMB_INO_T ino, pid_t pid, int tid, int fnum)
 595 {
 596         TDB_DATA kbuf, dbuf;
 597         int count, i, j, dcount=0;
 598         struct lock_struct *locks;
 599
 600         kbuf = locking_key(dev,ino);
 601
 602         dbuf.dptr = NULL;
 603
 604         tdb_chainlock(tdb, kbuf);
 605         dbuf = tdb_fetch(tdb, kbuf);
 606
 607         if (!dbuf.dptr) goto fail;
 608
 609         /* there are existing locks - remove any for this fnum */
 610         locks = (struct lock_struct *)dbuf.dptr;
 611         count = dbuf.dsize / sizeof(*locks);
 612
 613         for (i=0; i<count; i++) {
 614                 struct lock_struct *lock = &locks[i];
 615
 616                 if (lock->context.tid == tid &&
 617                     lock->context.pid == pid &&
 618                     lock->fnum == fnum) {
 619
 620                         /* Send unlock messages to any pending waiters that overlap. */
 621                         for (j=0; j<count; j++) {
 622                                 struct lock_struct *pend_lock = &locks[j];
 623
 624                                 /* Ignore our own or non-pending locks. */
 625                                 if (pend_lock->lock_type != PENDING_LOCK)
 626                                         continue;
 627
 628                                 if (pend_lock->context.tid == tid &&
 629                                     pend_lock->context.pid == pid &&
 630                                     pend_lock->fnum == fnum)
 631                                         continue;
 632
 633                                 /* We could send specific lock info here... */
 634                                 if (brl_pending_overlap(lock, pend_lock))
 635                                         message_send_pid(pend_lock->context.pid,
 636                                                         MSG_SMB_UNLOCK,
 637                                                         NULL, 0, True);
 638                         }
 639
 640                         /* found it - delete it */
 641                         if (count > 1 && i < count-1) {
 642                                 memmove(&locks[i], &locks[i+1],
 643                                         sizeof(*locks)*((count-1) - i));
 644                         }
 645                         count--;
 646                         i--;
 647                         dcount++;
 648                 }
 649         }
 650
 651         if (count == 0) {
 652                 tdb_delete(tdb, kbuf);
 653         } else if (count < (dbuf.dsize / sizeof(*locks))) {
 654                 dbuf.dsize -= dcount * sizeof(*locks);
 655                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 656         }
 657
 658         /* we didn't find it */
 659  fail:
 660         SAFE_FREE(dbuf.dptr);
 661         tdb_chainunlock(tdb, kbuf);
 662 }
 663
 664 /****************************************************************************
 665  Traverse the whole database with this function, calling traverse_callback
 666  on each lock.
 667 ****************************************************************************/
 668
 669 static int traverse_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
 670 {
 671         struct lock_struct *locks;
 672         struct lock_key *key;
 673         int i;
 674
 675         BRLOCK_FN(traverse_callback) = (BRLOCK_FN_CAST())state;
 676
 677         locks = (struct lock_struct *)dbuf.dptr;
 678         key = (struct lock_key *)kbuf.dptr;
 679
 680         for (i=0;i<dbuf.dsize/sizeof(*locks);i++) {
 681                 traverse_callback(key->device, key->inode,
 682                                   locks[i].context.pid,
 683                                   locks[i].lock_type,
 684                                   locks[i].start,
 685                                   locks[i].size);
 686         }
 687         return 0;
 688 }
 689
 690 /*******************************************************************
 691  Call the specified function on each lock in the database.
 692 ********************************************************************/
 693
 694 int brl_forall(BRLOCK_FN(fn))
 695 {
 696         if (!tdb) return 0;
 697         return tdb_traverse(tdb, traverse_fn, (void *)fn);
 698 }