summaryrefslogtreecommitdiff
path: root/source3/locking/brlock.c
blob: 60c94c2b98df62feb1ee6bf9cdd8b1e16dc2d509 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
/* 
   Unix SMB/CIFS implementation.
   byte range locking code
   Updated to handle range splits/merges.

   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 1992-2000
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* This module implements a tdb based byte range locking service,
   replacing the fcntl() based byte range locking previously
   used. This allows us to provide the same semantics as NT */

#include "includes.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING

#define ZERO_ZERO 0

/* This contains elements that differentiate locks. The smbpid is a
   client supplied pid, and is essentially the locking context for
   this client */

struct lock_context {
	uint16 smbpid;
	uint16 tid;
	struct process_id pid;
};

/* The data in brlock records is an unsorted linear array of these
   records.  It is unnecessary to store the count as tdb provides the
   size of the record */

struct lock_struct {
	struct lock_context context;
	br_off start;
	br_off size;
	int fnum;
	enum brl_type lock_type;
	enum brl_flavour lock_flav;
};

/* The open brlock.tdb database. */

static TDB_CONTEXT *tdb;

/****************************************************************************
 Debug info at level 10 for lock struct.
****************************************************************************/

static void print_lock_struct(unsigned int i, struct lock_struct *pls)
{
	DEBUG(10,("[%u]: smbpid = %u, tid = %u, pid = %u, ",
			i,
			(unsigned int)pls->context.smbpid,
			(unsigned int)pls->context.tid,
			(unsigned int)procid_to_pid(&pls->context.pid) ));
	
	DEBUG(10,("start = %.0f, size = %.0f, fnum = %d, %s %s\n",
		(double)pls->start,
		(double)pls->size,
		pls->fnum,
		lock_type_name(pls->lock_type),
		lock_flav_name(pls->lock_flav) ));
}

/****************************************************************************
 See if two locking contexts are equal.
****************************************************************************/

static BOOL brl_same_context(const struct lock_context *ctx1, 
			     const struct lock_context *ctx2)
{
	return (procid_equal(&ctx1->pid, &ctx2->pid) &&
		(ctx1->smbpid == ctx2->smbpid) &&
		(ctx1->tid == ctx2->tid));
}

/****************************************************************************
 See if lck1 and lck2 overlap.
****************************************************************************/

static BOOL brl_overlap(const struct lock_struct *lck1,
                        const struct lock_struct *lck2)
{
	/* this extra check is not redundent - it copes with locks
	   that go beyond the end of 64 bit file space */
	if (lck1->size != 0 &&
	    lck1->start == lck2->start &&
	    lck1->size == lck2->size) {
		return True;
	}

	if (lck1->start >= (lck2->start+lck2->size) ||
	    lck2->start >= (lck1->start+lck1->size)) {
		return False;
	}
	return True;
}

/****************************************************************************
 See if lock2 can be added when lock1 is in place.
****************************************************************************/

static BOOL brl_conflict(const struct lock_struct *lck1, 
			 const struct lock_struct *lck2)
{
	/* Ignore PENDING locks. */
	if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
		return False;

	/* Read locks never conflict. */
	if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
		return False;
	}

	if (brl_same_context(&lck1->context, &lck2->context) &&
	    lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
		return False;
	}

	return brl_overlap(lck1, lck2);
} 

/****************************************************************************
 See if lock2 can be added when lock1 is in place - when both locks are POSIX
 flavour. POSIX locks ignore fnum - they only care about dev/ino which we
 know already match.
****************************************************************************/

static BOOL brl_conflict_posix(const struct lock_struct *lck1, 
			 	const struct lock_struct *lck2)
{
#if defined(DEVELOPER)
	SMB_ASSERT(lck1->lock_flav == POSIX_LOCK);
	SMB_ASSERT(lck2->lock_flav == POSIX_LOCK);
#endif

	/* Ignore PENDING locks. */
	if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
		return False;

	/* Read locks never conflict. */
	if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
		return False;
	}

	/* Locks on the same context con't conflict. Ignore fnum. */
	if (brl_same_context(&lck1->context, &lck2->context)) {
		return False;
	}

	/* One is read, the other write, or the context is different,
	   do they overlap ? */
	return brl_overlap(lck1, lck2);
} 

#if ZERO_ZERO
static BOOL brl_conflict1(const struct lock_struct *lck1, 
			 const struct lock_struct *lck2)
{
	if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
		return False;

	if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
		return False;
	}

	if (brl_same_context(&lck1->context, &lck2->context) &&
	    lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
		return False;
	}

	if (lck2->start == 0 && lck2->size == 0 && lck1->size != 0) {
		return True;
	}

	if (lck1->start >= (lck2->start + lck2->size) ||
	    lck2->start >= (lck1->start + lck1->size)) {
		return False;
	}
	    
	return True;
} 
#endif

/****************************************************************************
 Check to see if this lock conflicts, but ignore our own locks on the
 same fnum only. This is the read/write lock check code path.
 This is never used in the POSIX lock case.
****************************************************************************/

static BOOL brl_conflict_other(const struct lock_struct *lck1, const struct lock_struct *lck2)
{
	if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
		return False;

	if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) 
		return False;

	/* POSIX flavour locks never conflict here - this is only called
	   in the read/write path. */

	if (lck1->lock_flav == POSIX_LOCK && lck2->lock_flav == POSIX_LOCK)
		return False;

	/*
	 * Incoming WRITE locks conflict with existing READ locks even
	 * if the context is the same. JRA. See LOCKTEST7 in smbtorture.
	 */

	if (!(lck2->lock_type == WRITE_LOCK && lck1->lock_type == READ_LOCK)) {
		if (brl_same_context(&lck1->context, &lck2->context) &&
					lck1->fnum == lck2->fnum)
			return False;
	}

	return brl_overlap(lck1, lck2);
} 

/****************************************************************************
 Amazingly enough, w2k3 "remembers" whether the last lock failure
 is the same as this one and changes its error code. I wonder if any
 app depends on this ?
****************************************************************************/

static NTSTATUS brl_lock_failed(const struct lock_struct *lock)
{
	static struct lock_struct last_lock_failure;

	if (brl_same_context(&lock->context, &last_lock_failure.context) &&
			lock->fnum == last_lock_failure.fnum &&
			lock->start == last_lock_failure.start &&
			lock->size == last_lock_failure.size) {
		return NT_STATUS_FILE_LOCK_CONFLICT;
	}
	last_lock_failure = *lock;
	if (lock->start >= 0xEF000000 &&
			(lock->start >> 63) == 0) {
		/* amazing the little things you learn with a test
		   suite. Locks beyond this offset (as a 64 bit
		   number!) always generate the conflict error code,
		   unless the top bit is set */
		return NT_STATUS_FILE_LOCK_CONFLICT;
	}
	return NT_STATUS_LOCK_NOT_GRANTED;
}

/****************************************************************************
 Open up the brlock.tdb database.
****************************************************************************/

void brl_init(int read_only)
{
	if (tdb) {
		return;
	}
	tdb = tdb_open_log(lock_path("brlock.tdb"),
			lp_open_files_db_hash_size(),
			TDB_DEFAULT|(read_only?0x0:TDB_CLEAR_IF_FIRST),
			read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644 );
	if (!tdb) {
		DEBUG(0,("Failed to open byte range locking database %s\n",
			lock_path("brlock.tdb")));
		return;
	}
}

/****************************************************************************
 Close down the brlock.tdb database.
****************************************************************************/

void brl_shutdown(int read_only)
{
	if (!tdb) {
		return;
	}
	tdb_close(tdb);
}

#if ZERO_ZERO
/****************************************************************************
 Compare two locks for sorting.
****************************************************************************/

static int lock_compare(const struct lock_struct *lck1, 
			 const struct lock_struct *lck2)
{
	if (lck1->start != lck2->start) {
		return (lck1->start - lck2->start);
	}
	if (lck2->size != lck1->size) {
		return ((int)lck1->size - (int)lck2->size);
	}
	return 0;
}
#endif

/****************************************************************************
 Lock a range of bytes - Windows lock semantics.
****************************************************************************/

static NTSTATUS brl_lock_windows(struct byte_range_lock *br_lck,
			const struct lock_struct *plock,
			BOOL *my_lock_ctx)
{
	unsigned int i;
	files_struct *fsp = br_lck->fsp;
	struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;

	for (i=0; i < br_lck->num_locks; i++) {
		/* Do any Windows or POSIX locks conflict ? */
		if (brl_conflict(&locks[i], plock)) {
			NTSTATUS status = brl_lock_failed(plock);;
			/* Did we block ourselves ? */
			if (brl_same_context(&locks[i].context, &plock->context)) {
				*my_lock_ctx = True;
			}
			return status;
		}
#if ZERO_ZERO
		if (plock->start == 0 && plock->size == 0 && 
				locks[i].size == 0) {
			break;
		}
#endif
	}

	/* We can get the Windows lock, now see if it needs to
	   be mapped into a lower level POSIX one, and if so can
	   we get it ? We tell the lower lock layer about the
	   lock type so it can cope with the difference between
	   Windows "stacking" locks and POSIX "flat" ones. */

	if ((plock->lock_type != PENDING_LOCK) && lp_posix_locking(SNUM(fsp->conn))) {
		if (!set_posix_lock(fsp, plock->start, plock->size, plock->lock_type, WINDOWS_LOCK)) {
			if (errno == EACCES || errno == EAGAIN) {
				return NT_STATUS_FILE_LOCK_CONFLICT;
			} else {
				return map_nt_error_from_unix(errno);
			}
		}
	}

	/* no conflicts - add it to the list of locks */
	locks = (struct lock_struct *)SMB_REALLOC(locks, (br_lck->num_locks + 1) * sizeof(*locks));
	if (!locks) {
		return NT_STATUS_NO_MEMORY;
	}

	memcpy(&locks[br_lck->num_locks], plock, sizeof(struct lock_struct));
	br_lck->num_locks += 1;
	br_lck->lock_data = (void *)locks;
	br_lck->modified = True;

	return NT_STATUS_OK;
}

/****************************************************************************
 Cope with POSIX range splits and merges.
****************************************************************************/

static unsigned int brlock_posix_split_merge(struct lock_struct *lck_arr,
						const struct lock_struct *ex,
						const struct lock_struct *plock,
						BOOL *lock_was_added)
{
	BOOL lock_types_differ = (ex->lock_type != plock->lock_type);

	/* We can't merge non-conflicting locks on different context - ignore fnum. */

	if (!brl_same_context(&ex->context, &plock->context)) {
		/* Just copy. */
		memcpy(&lck_arr[0], ex, sizeof(struct lock_struct));
		return 1;
	}

	/* We now know we have the same context. */

	/* Did we overlap ? */

/*********************************************
                                             +---------+
                                             | ex      |
                                             +---------+
                                +-------+
                                | plock |
                                +-------+
OR....
             +---------+
             |  ex     |
             +---------+
**********************************************/

	if ( (ex->start >= (plock->start + plock->size)) ||
			(plock->start >= (ex->start + ex->size))) {
		/* No overlap with this lock - copy existing. */
		memcpy(&lck_arr[0], ex, sizeof(struct lock_struct));
		return 1;
	}

/*********************************************
                +---------+
                |  ex     |
                +---------+
        +---------------------------+
        |       plock               | -> replace with plock.
        +---------------------------+
**********************************************/

	if ( (ex->start >= plock->start) &&
			(ex->start + ex->size <= plock->start + plock->size) ) {
		memcpy(&lck_arr[0], plock, sizeof(struct lock_struct));
		*lock_was_added = True;
		return 1;
	}

/*********************************************
                +---------------+
                |  ex           |
                +---------------+
        +---------------+
        |   plock       |
        +---------------+
BECOMES....
        +---------------+-------+
        |   plock       | ex    | - different lock types.
        +---------------+-------+
OR....
        +-----------------------+
        |   ex                  | - same lock type.
        +-----------------------+
**********************************************/

	if ( (ex->start >= plock->start) &&
				(ex->start < plock->start + plock->size) &&
				(ex->start + ex->size > plock->start + plock->size) ) {

		*lock_was_added = True;

		/* If the lock types are the same, we merge, if different, we
		   add the new lock before the old. */

		if (lock_types_differ) {
			/* Add new. */
			memcpy(&lck_arr[0], plock, sizeof(struct lock_struct));
			memcpy(&lck_arr[1], ex, sizeof(struct lock_struct));
			/* Adjust existing start and size. */
			lck_arr[1].start = plock->start + plock->size;
			lck_arr[1].size = (ex->start + ex->size) - (plock->start + plock->size);
			return 2;
		} else {
			/* Merge. */
			memcpy(&lck_arr[0], plock, sizeof(struct lock_struct));
			/* Set new start and size. */
			lck_arr[0].start = plock->start;
			lck_arr[0].size = (ex->start + ex->size) - plock->start;
			return 1;
		}
	}

/*********************************************
   +---------------+
   |  ex           |
   +---------------+
           +---------------+
           |   plock       |
           +---------------+
BECOMES....
   +-------+---------------+
   | ex    |   plock       | - different lock types
   +-------+---------------+

OR
   +-----------------------+
   | ex                    | - same lock type.
   +-----------------------+

**********************************************/

	if ( (ex->start < plock->start) &&
			(ex->start + ex->size > plock->start) &&
			(ex->start + ex->size <= plock->start + plock->size) ) {

		*lock_was_added = True;

		/* If the lock types are the same, we merge, if different, we
		   add the new lock after the old. */

		if (lock_types_differ) {
			memcpy(&lck_arr[0], ex, sizeof(struct lock_struct));
			memcpy(&lck_arr[1], plock, sizeof(struct lock_struct));
			/* Adjust existing size. */
			lck_arr[0].size = plock->start - ex->start;
			return 2;
		} else {
			/* Merge. */
			memcpy(&lck_arr[0], ex, sizeof(struct lock_struct));
			/* Adjust existing size. */
			lck_arr[0].size = (plock->start + plock->size) - ex->start;
			return 1;
		}
	}

/*********************************************
        +---------------------------+
        |        ex                 |
        +---------------------------+
                +---------+
                |  plock  |
                +---------+
BECOMES.....
        +-------+---------+---------+
        | ex    |  plock  | ex      | - different lock types.
        +-------+---------+---------+
OR
        +---------------------------+
        |        ex                 | - same lock type.
        +---------------------------+
**********************************************/

	if ( (ex->start < plock->start) && (ex->start + ex->size > plock->start + plock->size) ) {
		*lock_was_added = True;

		if (lock_types_differ) {

			/* We have to split ex into two locks here. */

			memcpy(&lck_arr[0], ex, sizeof(struct lock_struct));
			memcpy(&lck_arr[1], plock, sizeof(struct lock_struct));
			memcpy(&lck_arr[2], ex, sizeof(struct lock_struct));

			/* Adjust first existing size. */
			lck_arr[0].size = plock->start - ex->start;

			/* Adjust second existing start and size. */
			lck_arr[2].start = plock->start + plock->size;
			lck_arr[2].size = (ex->start + ex->size) - (plock->start + plock->size);
			return 3;
		} else {
			/* Just eat plock. */
			memcpy(&lck_arr[0], ex, sizeof(struct lock_struct));
			return 1;
		}
	}

	/* Never get here. */
	smb_panic("brlock_posix_split_merge\n");
	/* Notreached. */
	abort();
}

/****************************************************************************
 Lock a range of bytes - POSIX lock semantics.
 We must cope with range splits and merges.
****************************************************************************/

static NTSTATUS brl_lock_posix(struct byte_range_lock *br_lck,
			const struct lock_struct *plock,
			BOOL *my_lock_ctx)
{
	unsigned int i, count;
	struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;
	struct lock_struct *tp;
	BOOL lock_was_added = False;

	/* No zero-zero locks for POSIX. */
	if (plock->start == 0 && plock->size == 0) {
		return NT_STATUS_INVALID_PARAMETER;
	}

	/* Don't allow 64-bit lock wrap. */
	if (plock->start + plock->size < plock->start ||
			plock->start + plock->size < plock->size) {
		return NT_STATUS_INVALID_PARAMETER;
	}

	/* The worst case scenario here is we have to split an
	   existing POSIX lock range into two, and add our lock,
	   so we need at most 2 more entries. */

	tp = SMB_MALLOC_ARRAY(struct lock_struct, (br_lck->num_locks + 2));
	if (!tp) {
		return NT_STATUS_NO_MEMORY;
	}
	
	count = 0;
	for (i=0; i < br_lck->num_locks; i++) {
		if (locks[i].lock_flav == WINDOWS_LOCK) {
			/* Do any Windows flavour locks conflict ? */
			if (brl_conflict(&locks[i], plock)) {
				/* Did we block ourselves ? */
				if (brl_same_context(&locks[i].context, &plock->context)) {
					*my_lock_ctx = True;
				}
				/* No games with error messages. */
				SAFE_FREE(tp);
				return NT_STATUS_FILE_LOCK_CONFLICT;
			}
			/* Just copy the Windows lock into the new array. */
			memcpy(&tp[count], &locks[i], sizeof(struct lock_struct));
			count++;
		} else {
			/* POSIX conflict semantics are different. */
			if (brl_conflict_posix(&locks[i], plock)) {
				/* Can't block ourselves with POSIX locks. */
				/* No games with error messages. */
				SAFE_FREE(tp);
				return NT_STATUS_FILE_LOCK_CONFLICT;
			}

			/* Work out overlaps. */
			count += brlock_posix_split_merge(&tp[count], &locks[i], plock, &lock_was_added);
		}
	}

	/* We can get the POSIX lock, now see if it needs to
	   be mapped into a lower level POSIX one, and if so can
	   we get it ? We well the lower lock layer about the
	   lock type so it can cope with the difference between
	   Windows "stacking" locks and POSIX "flat" ones. */

#if 0
	/* FIXME - this call doesn't work correctly yet for POSIX locks... */

	if ((plock->lock_type != PENDING_LOCK) && lp_posix_locking(SNUM(fsp->conn))) {
		files_struct *fsp = br_lck->fsp;

		if (!set_posix_lock(fsp, plock->start, plock->size, plock->lock_type, POSIX_LOCK)) {
			if (errno == EACCES || errno == EAGAIN) {
				SAFE_FREE(tp);
				return NT_STATUS_FILE_LOCK_CONFLICT;
			} else {
				SAFE_FREE(tp);
				return map_nt_error_from_unix(errno);
			}
		}
	}
#endif

	if (!lock_was_added) {
		memcpy(&tp[count], plock, sizeof(struct lock_struct));
		count++;
	}

	/* Realloc so we don't leak entries per lock call. */
	tp = (struct lock_struct *)SMB_REALLOC(tp, count * sizeof(*locks));
	if (!tp) {
		return NT_STATUS_NO_MEMORY;
	}
	br_lck->num_locks = count;
	br_lck->lock_data = (void *)tp;
	br_lck->modified = True;
	return NT_STATUS_OK;
}

/****************************************************************************
 Lock a range of bytes.
****************************************************************************/

NTSTATUS brl_lock(struct byte_range_lock *br_lck,
		uint16 smbpid,
		struct process_id pid,
		br_off start,
		br_off size, 
		enum brl_type lock_type,
		enum brl_flavour lock_flav,
		BOOL *my_lock_ctx)
{
	NTSTATUS ret;
	struct lock_struct lock;

	*my_lock_ctx = False;

#if !ZERO_ZERO
	if (start == 0 && size == 0) {
		DEBUG(0,("client sent 0/0 lock - please report this\n"));
	}
#endif

	lock.context.smbpid = smbpid;
	lock.context.pid = pid;
	lock.context.tid = br_lck->fsp->conn->cnum;
	lock.start = start;
	lock.size = size;
	lock.fnum = br_lck->fsp->fnum;
	lock.lock_type = lock_type;
	lock.lock_flav = lock_flav;

	if (lock_flav == WINDOWS_LOCK) {
		ret = brl_lock_windows(br_lck, &lock, my_lock_ctx);
	} else {
		ret = brl_lock_posix(br_lck, &lock, my_lock_ctx);
	}

#if ZERO_ZERO
	/* sort the lock list */
	qsort(br_lck->lock_data, (size_t)br_lck->num_locks, sizeof(lock), lock_compare);
#endif

	return ret;
}

/****************************************************************************
 Check if an unlock overlaps a pending lock.
****************************************************************************/

static BOOL brl_pending_overlap(struct lock_struct *lock, struct lock_struct *pend_lock)
{
	if ((lock->start <= pend_lock->start) && (lock->start + lock->size > pend_lock->start))
		return True;
	if ((lock->start >= pend_lock->start) && (lock->start <= pend_lock->start + pend_lock->size))
		return True;
	return False;
}

/****************************************************************************
 Unlock a range of bytes - Windows semantics.
****************************************************************************/

static BOOL brl_unlock_windows(struct byte_range_lock *br_lck, const struct lock_struct *plock)
{
	unsigned int i, j;
	struct lock_struct *lock = NULL;
	struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;

#if ZERO_ZERO
	for (i = 0; i < br_lck->num_locks; i++) {
		lock = &locks[i];

		if (lock->lock_type == WRITE_LOCK &&
		    brl_same_context(&lock->context, &plock->context) &&
		    lock->fnum == plock->fnum &&
		    lock->lock_flav == WINDOWS_LOCK &&
		    lock->start == plock->start &&
		    lock->size == plock->size) {

			/* found it - delete it */
			if (i < br_lck->num_locks - 1) {
				memmove(&locks[i], &locks[i+1], 
					sizeof(*locks)*((br_lck->num_locks-1) - i));
			}

			br_lck->num_locks -= 1;
			br_lck->modified = True;
			return True;
		}
	}
#endif

	for (i = 0; i < br_lck->num_locks; i++) {
		lock = &locks[i];

		/* Only remove our own locks that match in start, size, and flavour. */
		if (brl_same_context(&lock->context, &plock->context) &&
					lock->fnum == plock->fnum &&
					lock->lock_flav == WINDOWS_LOCK &&
					lock->start == plock->start &&
					lock->size == plock->size ) {
			break;
		}
	}

	if (i == br_lck->num_locks) {
		/* we didn't find it */
		return False;
	}

	/* Unlock any POSIX regions. */
	if(lp_posix_locking(br_lck->fsp->conn->cnum)) {
		release_posix_lock(br_lck->fsp, plock->start, plock->size);
	}

	/* Send unlock messages to any pending waiters that overlap. */
	for (j=0; j < br_lck->num_locks; j++) {
		struct lock_struct *pend_lock = &locks[j];

		/* Ignore non-pending locks. */
		if (pend_lock->lock_type != PENDING_LOCK) {
			continue;
		}

		/* We could send specific lock info here... */
		if (brl_pending_overlap(lock, pend_lock)) {
			DEBUG(10,("brl_unlock: sending unlock message to pid %s\n",
				procid_str_static(&pend_lock->context.pid )));

			become_root();
			message_send_pid(pend_lock->context.pid,
					MSG_SMB_UNLOCK,
					NULL, 0, True);
			unbecome_root();
		}
	}

	/* Actually delete the lock. */
	if (i < br_lck->num_locks - 1) {
		memmove(&locks[i], &locks[i+1], 
			sizeof(*locks)*((br_lck->num_locks-1) - i));
	}

	br_lck->num_locks -= 1;
	br_lck->modified = True;
	return True;
}

/****************************************************************************
 Unlock a range of bytes - POSIX semantics.
****************************************************************************/

static BOOL brl_unlock_posix(struct byte_range_lock *br_lck, const struct lock_struct *plock)
{
	unsigned int i, j, count;
	struct lock_struct *lock = NULL;
	struct lock_struct *tp;
	struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;
	BOOL overlap_found = False;

	/* No zero-zero locks for POSIX. */
	if (plock->start == 0 && plock->size == 0) {
		return False;
	}

	/* Don't allow 64-bit lock wrap. */
	if (plock->start + plock->size < plock->start ||
			plock->start + plock->size < plock->size) {
		DEBUG(10,("brl_unlock_posix: lock wrap\n"));
		return False;
	}

	/* The worst case scenario here is we have to split an
	   existing POSIX lock range into two, so we need at most
	   1 more entry. */

	tp = SMB_MALLOC_ARRAY(struct lock_struct, (br_lck->num_locks + 1));
	if (!tp) {
		DEBUG(10,("brl_unlock_posix: malloc fail\n"));
		return False;
	}

	count = 0;
	for (i = 0; i < br_lck->num_locks; i++) {
		struct lock_struct tmp_lock[3];
		BOOL lock_was_added = False;
		unsigned int tmp_count;

		lock = &locks[i];

		/* Only remove our own locks - ignore fnum. */
		if (lock->lock_type == PENDING_LOCK ||
				!brl_same_context(&lock->context, &plock->context)) {
			memcpy(&tp[count], lock, sizeof(struct lock_struct));
			count++;
			continue;
		}

		/* Work out overlaps. */
		tmp_count = brlock_posix_split_merge(&tmp_lock[0], &locks[i], plock, &lock_was_added);

		if (tmp_count == 1) {
			/* Ether the locks didn't overlap, or the unlock completely
			   overlapped this lock. If it didn't overlap, then there's
			   no change in the locks. */
			if (tmp_lock[0].lock_type != UNLOCK_LOCK) {
				SMB_ASSERT(tmp_lock[0].lock_type == locks[i].lock_type);
				/* No change in this lock. */
				memcpy(&tp[count], &tmp_lock[0], sizeof(struct lock_struct));
				count++;
			} else {
				SMB_ASSERT(tmp_lock[0].lock_type == UNLOCK_LOCK);
				overlap_found = True;
			}
			continue;
		} else if (tmp_count == 2) {
			/* The unlock overlapped an existing lock. Copy the truncated
			   lock into the lock array. */
			if (tmp_lock[0].lock_type != UNLOCK_LOCK) {
				SMB_ASSERT(tmp_lock[0].lock_type == locks[i].lock_type);
				SMB_ASSERT(tmp_lock[1].lock_type == UNLOCK_LOCK);
				memcpy(&tp[count], &tmp_lock[0], sizeof(struct lock_struct));
			} else {
				SMB_ASSERT(tmp_lock[0].lock_type == UNLOCK_LOCK);
				SMB_ASSERT(tmp_lock[1].lock_type == locks[i].lock_type);
				memcpy(&tp[count], &tmp_lock[1], sizeof(struct lock_struct));
			}
			count++;
			overlap_found = True;
			continue;
		} else {
			/* tmp_count == 3 - (we split a lock range in two). */
			SMB_ASSERT(tmp_lock[0].lock_type == locks[i].lock_type);
			SMB_ASSERT(tmp_lock[1].lock_type == UNLOCK_LOCK);
			SMB_ASSERT(tmp_lock[2].lock_type != locks[i].lock_type);

			memcpy(&tp[count], &tmp_lock[0], sizeof(struct lock_struct));
			count++;
			memcpy(&tp[count], &tmp_lock[2], sizeof(struct lock_struct));
			count++;
			overlap_found = True;
			/* Optimisation... */
			/* We know we're finished here as we can't overlap any
			   more POSIX locks. Copy the rest of the lock array. */
			if (i < br_lck->num_locks - 1) {
				memcpy(&tp[count], &locks[i+1], 
					sizeof(*locks)*((br_lck->num_locks-1) - i));
				count += ((br_lck->num_locks-1) - i);
			}
			break;
		}
	}

	if (!overlap_found) {
		/* Just ignore - no change. */
		SAFE_FREE(tp);
		DEBUG(10,("brl_unlock_posix: No overlap - unlocked.\n"));
		return True;
	}

#if 0
	/* FIXME - this call doesn't work correctly yet for POSIX locks... */

	/* Unlock any POSIX regions. */
	if(lp_posix_locking(br_lck->fsp->conn->cnum)) {
		release_posix_lock(br_lck->fsp, plock->start, plock->size);
	}
#endif

	/* Realloc so we don't leak entries per unlock call. */
	if (count) {
		tp = (struct lock_struct *)SMB_REALLOC(tp, count * sizeof(*locks));
		if (!tp) {
			DEBUG(10,("brl_unlock_posix: realloc fail\n"));
			return False;
		}
	} else {
		/* We deleted the last lock. */
		SAFE_FREE(tp);
		tp = NULL;
	}

	br_lck->num_locks = count;
	br_lck->lock_data = (void *)tp;
	br_lck->modified = True;

	/* Send unlock messages to any pending waiters that overlap. */
	locks = tp;

	for (j=0; j < br_lck->num_locks; j++) {
		struct lock_struct *pend_lock = &locks[j];

		/* Ignore non-pending locks. */
		if (pend_lock->lock_type != PENDING_LOCK) {
			continue;
		}

		/* We could send specific lock info here... */
		if (brl_pending_overlap(lock, pend_lock)) {
			DEBUG(10,("brl_unlock: sending unlock message to pid %s\n",
				procid_str_static(&pend_lock->context.pid )));

			become_root();
			message_send_pid(pend_lock->context.pid,
					MSG_SMB_UNLOCK,
					NULL, 0, True);
			unbecome_root();
		}
	}

	return True;
}

/****************************************************************************
 Unlock a range of bytes.
****************************************************************************/

BOOL brl_unlock(struct byte_range_lock *br_lck,
		uint16 smbpid,
		struct process_id pid,
		br_off start,
		br_off size,
		enum brl_flavour lock_flav)
{
	struct lock_struct lock;

	lock.context.smbpid = smbpid;
	lock.context.pid = pid;
	lock.context.tid = br_lck->fsp->conn->cnum;
	lock.start = start;
	lock.size = size;
	lock.fnum = br_lck->fsp->fnum;
	lock.lock_type = UNLOCK_LOCK;
	lock.lock_flav = lock_flav;

	if (lock_flav == WINDOWS_LOCK) {
		return brl_unlock_windows(br_lck, &lock);
	} else {
		return brl_unlock_posix(br_lck, &lock);
	}
}

/****************************************************************************
 Test if we could add a lock if we wanted to.
 Returns True if the region required is currently unlocked, False if locked.
****************************************************************************/

BOOL brl_locktest(struct byte_range_lock *br_lck,
		uint16 smbpid,
		struct process_id pid,
		br_off start,
		br_off size, 
		enum brl_type lock_type,
		enum brl_flavour lock_flav)
{
	BOOL ret = True;
	unsigned int i;
	struct lock_struct lock;
	struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;
	files_struct *fsp = br_lck->fsp;

	lock.context.smbpid = smbpid;
	lock.context.pid = pid;
	lock.context.tid = br_lck->fsp->conn->cnum;
	lock.start = start;
	lock.size = size;
	lock.fnum = fsp->fnum;
	lock.lock_type = lock_type;
	lock.lock_flav = lock_flav;

	/* Make sure existing locks don't conflict */
	for (i=0; i < br_lck->num_locks; i++) {
		/*
		 * Our own locks don't conflict.
		 */
		if (brl_conflict_other(&locks[i], &lock)) {
			return False;
		}
	}

	/*
	 * There is no lock held by an SMB daemon, check to
	 * see if there is a POSIX lock from a UNIX or NFS process.
	 * This only conflicts with Windows locks, not POSIX locks.
	 */

	if(lp_posix_locking(fsp->conn->cnum) && (lock_flav == WINDOWS_LOCK)) {
		ret = is_posix_locked(fsp, &start, &size, &lock_type, WINDOWS_LOCK);

		DEBUG(10,("brl_locktest: posix start=%.0f len=%.0f %s for fnum %d file %s\n",
			(double)start, (double)size, ret ? "locked" : "unlocked",
			fsp->fnum, fsp->fsp_name ));

		/* We need to return the inverse of is_posix_locked. */
		ret = !ret;
        }

	/* no conflicts - we could have added it */
	return ret;
}

/****************************************************************************
 Query for existing locks.
****************************************************************************/

NTSTATUS brl_lockquery(struct byte_range_lock *br_lck,
		uint16 *psmbpid,
		struct process_id pid,
		br_off *pstart,
		br_off *psize, 
		enum brl_type *plock_type,
		enum brl_flavour lock_flav)
{
	unsigned int i;
	struct lock_struct lock;
	struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;
	files_struct *fsp = br_lck->fsp;

	lock.context.smbpid = *psmbpid;
	lock.context.pid = pid;
	lock.context.tid = br_lck->fsp->conn->cnum;
	lock.start = *pstart;
	lock.size = *psize;
	lock.fnum = fsp->fnum;
	lock.lock_type = *plock_type;
	lock.lock_flav = lock_flav;

	/* Make sure existing locks don't conflict */
	for (i=0; i < br_lck->num_locks; i++) {
		struct lock_struct *exlock = &locks[i];
		BOOL conflict = False;

		if (exlock->lock_flav == WINDOWS_LOCK) {
			conflict = brl_conflict(exlock, &lock);
		} else {	
			conflict = brl_conflict_posix(exlock, &lock);
		}

		if (conflict) {
			*psmbpid = exlock->context.smbpid;
        		*pstart = exlock->start;
		        *psize = exlock->size;
        		*plock_type = exlock->lock_type;
			return NT_STATUS_LOCK_NOT_GRANTED;
		}
	}

	/*
	 * There is no lock held by an SMB daemon, check to
	 * see if there is a POSIX lock from a UNIX or NFS process.
	 */

	if(lp_posix_locking(fsp->conn->cnum)) {
		BOOL ret = is_posix_locked(fsp, pstart, psize, plock_type, POSIX_LOCK);

		DEBUG(10,("brl_lockquery: posix start=%.0f len=%.0f %s for fnum %d file %s\n",
			(double)*pstart, (double)*psize, ret ? "locked" : "unlocked",
			fsp->fnum, fsp->fsp_name ));

		if (ret) {
			/* Hmmm. No clue what to set smbpid to - use -1. */
			*psmbpid = 0xFFFF;
			return NT_STATUS_LOCK_NOT_GRANTED;
		}
        }

	return NT_STATUS_OK;
}


/****************************************************************************
 Remove a particular pending lock.
****************************************************************************/

BOOL brl_remove_pending_lock(struct byte_range_lock *br_lck,
		uint16 smbpid,
		struct process_id pid,
		br_off start,
		br_off size,
		enum brl_flavour lock_flav)
{
	unsigned int i;
	struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;
	struct lock_context context;

	context.smbpid = smbpid;
	context.pid = pid;
	context.tid = br_lck->fsp->conn->cnum;

	for (i = 0; i < br_lck->num_locks; i++) {
		struct lock_struct *lock = &locks[i];

		/* For pending locks we *always* care about the fnum. */
		if (brl_same_context(&lock->context, &context) &&
				lock->fnum == br_lck->fsp->fnum &&
				lock->lock_type == PENDING_LOCK &&
				lock->lock_flav == lock_flav &&
				lock->start == start &&
				lock->size == size) {
			break;
		}
	}

	if (i == br_lck->num_locks) {
		/* Didn't find it. */
		return False;
	}

	if (i < br_lck->num_locks - 1) {
		/* Found this particular pending lock - delete it */
		memmove(&locks[i], &locks[i+1], 
			sizeof(*locks)*((br_lck->num_locks-1) - i));
	}

	br_lck->num_locks -= 1;
	br_lck->modified = True;
	return True;
}


/****************************************************************************
 Remove any locks associated with a open file.
****************************************************************************/

void brl_close_fnum(struct byte_range_lock *br_lck, struct process_id pid)
{
	files_struct *fsp = br_lck->fsp;
	uint16 tid = fsp->conn->cnum;
	int fnum = fsp->fnum;
	unsigned int i, j, dcount=0;
	struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;

	/* Remove any existing locks for this fnum (or any fnum if they're POSIX). */

	for (i=0; i < br_lck->num_locks; i++) {
		struct lock_struct *lock = &locks[i];
		BOOL del_this_lock = False;

		if (lock->context.tid == tid && procid_equal(&lock->context.pid, &pid)) {
			if ((lock->lock_flav == WINDOWS_LOCK) && (lock->fnum == fnum)) {
				del_this_lock = True;
			} else if (lock->lock_flav == POSIX_LOCK) {
				del_this_lock = True;
			}
		}

		if (del_this_lock) {
			/* Send unlock messages to any pending waiters that overlap. */
			for (j=0; j < br_lck->num_locks; j++) {
				struct lock_struct *pend_lock = &locks[j];

				/* Ignore our own or non-pending locks. */
				if (pend_lock->lock_type != PENDING_LOCK) {
					continue;
				}

				/* Optimisation - don't send to this fnum as we're
				   closing it. */
				if (pend_lock->context.tid == tid &&
				    procid_equal(&pend_lock->context.pid, &pid) &&
				    pend_lock->fnum == fnum) {
					continue;
				}

				/* We could send specific lock info here... */
				if (brl_pending_overlap(lock, pend_lock)) {
					become_root();
					message_send_pid(pend_lock->context.pid,
							MSG_SMB_UNLOCK,
							NULL, 0, True);
					unbecome_root();
				}
			}

			/* found it - delete it */
			if (br_lck->num_locks > 1 && i < br_lck->num_locks - 1) {
				memmove(&locks[i], &locks[i+1], 
					sizeof(*locks)*((br_lck->num_locks-1) - i));
			}
			br_lck->num_locks--;
			br_lck->modified = True;
			i--;
			dcount++;
		}
	}
}

/****************************************************************************
 Traverse the whole database with this function, calling traverse_callback
 on each lock.
****************************************************************************/

static int traverse_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
{
	struct lock_struct *locks;
	struct lock_key *key;
	int i;

	BRLOCK_FN(traverse_callback) = (BRLOCK_FN_CAST())state;

	locks = (struct lock_struct *)dbuf.dptr;
	key = (struct lock_key *)kbuf.dptr;

	for (i=0;i<dbuf.dsize/sizeof(*locks);i++) {
		traverse_callback(key->device,
				  key->inode,
				  locks[i].context.pid,
				  locks[i].lock_type,
				  locks[i].lock_flav,
				  locks[i].start,
				  locks[i].size);
	}
	return 0;
}

/*******************************************************************
 Call the specified function on each lock in the database.
********************************************************************/

int brl_forall(BRLOCK_FN(fn))
{
	if (!tdb) {
		return 0;
	}
	return tdb_traverse(tdb, traverse_fn, (void *)fn);
}

/*******************************************************************
 Store a potentially modified set of byte range lock data back into
 the database.
 Unlock the record.
********************************************************************/

static int byte_range_lock_destructor(void *p)
{
	struct byte_range_lock *br_lck =
		talloc_get_type_abort(p, struct byte_range_lock);
	TDB_DATA key;

	key.dptr = (char *)&br_lck->key;
	key.dsize = sizeof(struct lock_key);

	if (!br_lck->modified) {
		goto done;
	}

	if (br_lck->num_locks == 0) {
		/* No locks - delete this entry. */
		if (tdb_delete(tdb, key) == -1) {
			smb_panic("Could not delete byte range lock entry\n");
		}
	} else {
		TDB_DATA data;
		data.dptr = br_lck->lock_data;
		data.dsize = br_lck->num_locks * sizeof(struct lock_struct);

		if (tdb_store(tdb, key, data, TDB_REPLACE) == -1) {
			smb_panic("Could not store byte range mode entry\n");
		}
	}

 done:

	tdb_chainunlock(tdb, key);
	SAFE_FREE(br_lck->lock_data);
	return 0;
}

/*******************************************************************
 Fetch a set of byte range lock data from the database.
 Leave the record locked.
********************************************************************/

struct byte_range_lock *brl_get_locks(TALLOC_CTX *mem_ctx,
					files_struct *fsp)
{
	TDB_DATA key;
	TDB_DATA data;
	struct byte_range_lock *br_lck = TALLOC_P(mem_ctx, struct byte_range_lock);

	if (br_lck == NULL) {
		return NULL;
	}

	br_lck->fsp = fsp;
	br_lck->num_locks = 0;
	br_lck->modified = False;
	memset(&br_lck->key, '\0', sizeof(struct lock_key));
	br_lck->key.device = fsp->dev;
	br_lck->key.inode = fsp->inode;

	key.dptr = (char *)&br_lck->key;
	key.dsize = sizeof(struct lock_key);

	if (tdb_chainlock(tdb, key) != 0) {
		DEBUG(3, ("Could not lock byte range lock entry\n"));
		TALLOC_FREE(br_lck);
		return NULL;
	}

	talloc_set_destructor(br_lck, byte_range_lock_destructor);

	data = tdb_fetch(tdb, key);
	br_lck->lock_data = (void *)data.dptr;
	br_lck->num_locks = data.dsize / sizeof(struct lock_struct);

	if (DEBUGLEVEL >= 10) {
		unsigned int i;
		struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;
		DEBUG(10,("brl_get_locks: %u current locks on dev=%.0f, inode=%.0f\n",
			br_lck->num_locks,
			(double)fsp->dev, (double)fsp->inode ));
		for( i = 0; i < br_lck->num_locks; i++) {
			print_lock_struct(i, &locks[i]);
		}
	}
	return br_lck;
}