summaryrefslogtreecommitdiffstats
path: root/fs/ntfs3/run.c
blob: 12d8682f33b538dea9dcd1120b6a59a8a7999ccd (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
// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
 *
 * TODO: try to use extents tree (instead of array)
 */

#include <linux/blkdev.h>
#include <linux/fs.h>
#include <linux/log2.h>

#include "debug.h"
#include "ntfs.h"
#include "ntfs_fs.h"

/* runs_tree is a continues memory. Try to avoid big size. */
#define NTFS3_RUN_MAX_BYTES 0x10000

struct ntfs_run {
	CLST vcn; /* Virtual cluster number. */
	CLST len; /* Length in clusters. */
	CLST lcn; /* Logical cluster number. */
};

/*
 * run_lookup - Lookup the index of a MCB entry that is first <= vcn.
 *
 * Case of success it will return non-zero value and set
 * @index parameter to index of entry been found.
 * Case of entry missing from list 'index' will be set to
 * point to insertion position for the entry question.
 */
static bool run_lookup(const struct runs_tree *run, CLST vcn, size_t *index)
{
	size_t min_idx, max_idx, mid_idx;
	struct ntfs_run *r;

	if (!run->count) {
		*index = 0;
		return false;
	}

	min_idx = 0;
	max_idx = run->count - 1;

	/* Check boundary cases specially, 'cause they cover the often requests. */
	r = run->runs;
	if (vcn < r->vcn) {
		*index = 0;
		return false;
	}

	if (vcn < r->vcn + r->len) {
		*index = 0;
		return true;
	}

	r += max_idx;
	if (vcn >= r->vcn + r->len) {
		*index = run->count;
		return false;
	}

	if (vcn >= r->vcn) {
		*index = max_idx;
		return true;
	}

	do {
		mid_idx = min_idx + ((max_idx - min_idx) >> 1);
		r = run->runs + mid_idx;

		if (vcn < r->vcn) {
			max_idx = mid_idx - 1;
			if (!mid_idx)
				break;
		} else if (vcn >= r->vcn + r->len) {
			min_idx = mid_idx + 1;
		} else {
			*index = mid_idx;
			return true;
		}
	} while (min_idx <= max_idx);

	*index = max_idx + 1;
	return false;
}

/*
 * run_consolidate - Consolidate runs starting from a given one.
 */
static void run_consolidate(struct runs_tree *run, size_t index)
{
	size_t i;
	struct ntfs_run *r = run->runs + index;

	while (index + 1 < run->count) {
		/*
		 * I should merge current run with next
		 * if start of the next run lies inside one being tested.
		 */
		struct ntfs_run *n = r + 1;
		CLST end = r->vcn + r->len;
		CLST dl;

		/* Stop if runs are not aligned one to another. */
		if (n->vcn > end)
			break;

		dl = end - n->vcn;

		/*
		 * If range at index overlaps with next one
		 * then I will either adjust it's start position
		 * or (if completely matches) dust remove one from the list.
		 */
		if (dl > 0) {
			if (n->len <= dl)
				goto remove_next_range;

			n->len -= dl;
			n->vcn += dl;
			if (n->lcn != SPARSE_LCN)
				n->lcn += dl;
			dl = 0;
		}

		/*
		 * Stop if sparse mode does not match
		 * both current and next runs.
		 */
		if ((n->lcn == SPARSE_LCN) != (r->lcn == SPARSE_LCN)) {
			index += 1;
			r = n;
			continue;
		}

		/*
		 * Check if volume block
		 * of a next run lcn does not match
		 * last volume block of the current run.
		 */
		if (n->lcn != SPARSE_LCN && n->lcn != r->lcn + r->len)
			break;

		/*
		 * Next and current are siblings.
		 * Eat/join.
		 */
		r->len += n->len - dl;

remove_next_range:
		i = run->count - (index + 1);
		if (i > 1)
			memmove(n, n + 1, sizeof(*n) * (i - 1));

		run->count -= 1;
	}
}

/*
 * run_is_mapped_full
 *
 * Return: True if range [svcn - evcn] is mapped.
 */
bool run_is_mapped_full(const struct runs_tree *run, CLST svcn, CLST evcn)
{
	size_t i;
	const struct ntfs_run *r, *end;
	CLST next_vcn;

	if (!run_lookup(run, svcn, &i))
		return false;

	end = run->runs + run->count;
	r = run->runs + i;

	for (;;) {
		next_vcn = r->vcn + r->len;
		if (next_vcn > evcn)
			return true;

		if (++r >= end)
			return false;

		if (r->vcn != next_vcn)
			return false;
	}
}

bool run_lookup_entry(const struct runs_tree *run, CLST vcn, CLST *lcn,
		      CLST *len, size_t *index)
{
	size_t idx;
	CLST gap;
	struct ntfs_run *r;

	/* Fail immediately if nrun was not touched yet. */
	if (!run->runs)
		return false;

	if (!run_lookup(run, vcn, &idx))
		return false;

	r = run->runs + idx;

	if (vcn >= r->vcn + r->len)
		return false;

	gap = vcn - r->vcn;
	if (r->len <= gap)
		return false;

	*lcn = r->lcn == SPARSE_LCN ? SPARSE_LCN : (r->lcn + gap);

	if (len)
		*len = r->len - gap;
	if (index)
		*index = idx;

	return true;
}

/*
 * run_truncate_head - Decommit the range before vcn.
 */
void run_truncate_head(struct runs_tree *run, CLST vcn)
{
	size_t index;
	struct ntfs_run *r;

	if (run_lookup(run, vcn, &index)) {
		r = run->runs + index;

		if (vcn > r->vcn) {
			CLST dlen = vcn - r->vcn;

			r->vcn = vcn;
			r->len -= dlen;
			if (r->lcn != SPARSE_LCN)
				r->lcn += dlen;
		}

		if (!index)
			return;
	}
	r = run->runs;
	memmove(r, r + index, sizeof(*r) * (run->count - index));

	run->count -= index;

	if (!run->count) {
		kvfree(run->runs);
		run->runs = NULL;
		run->allocated = 0;
	}
}

/*
 * run_truncate - Decommit the range after vcn.
 */
void run_truncate(struct runs_tree *run, CLST vcn)
{
	size_t index;

	/*
	 * If I hit the range then
	 * I have to truncate one.
	 * If range to be truncated is becoming empty
	 * then it will entirely be removed.
	 */
	if (run_lookup(run, vcn, &index)) {
		struct ntfs_run *r = run->runs + index;

		r->len = vcn - r->vcn;

		if (r->len > 0)
			index += 1;
	}

	/*
	 * At this point 'index' is set to position that
	 * should be thrown away (including index itself)
	 * Simple one - just set the limit.
	 */
	run->count = index;

	/* Do not reallocate array 'runs'. Only free if possible. */
	if (!index) {
		kvfree(run->runs);
		run->runs = NULL;
		run->allocated = 0;
	}
}

/*
 * run_truncate_around - Trim head and tail if necessary.
 */
void run_truncate_around(struct runs_tree *run, CLST vcn)
{
	run_truncate_head(run, vcn);

	if (run->count >= NTFS3_RUN_MAX_BYTES / sizeof(struct ntfs_run) / 2)
		run_truncate(run, (run->runs + (run->count >> 1))->vcn);
}

/*
 * run_add_entry
 *
 * Sets location to known state.
 * Run to be added may overlap with existing location.
 *
 * Return: false if of memory.
 */
bool run_add_entry(struct runs_tree *run, CLST vcn, CLST lcn, CLST len,
		   bool is_mft)
{
	size_t used, index;
	struct ntfs_run *r;
	bool inrange;
	CLST tail_vcn = 0, tail_len = 0, tail_lcn = 0;
	bool should_add_tail = false;

	/*
	 * Lookup the insertion point.
	 *
	 * Execute bsearch for the entry containing
	 * start position question.
	 */
	inrange = run_lookup(run, vcn, &index);

	/*
	 * Shortcut here would be case of
	 * range not been found but one been added
	 * continues previous run.
	 * This case I can directly make use of
	 * existing range as my start point.
	 */
	if (!inrange && index > 0) {
		struct ntfs_run *t = run->runs + index - 1;

		if (t->vcn + t->len == vcn &&
		    (t->lcn == SPARSE_LCN) == (lcn == SPARSE_LCN) &&
		    (lcn == SPARSE_LCN || lcn == t->lcn + t->len)) {
			inrange = true;
			index -= 1;
		}
	}

	/*
	 * At this point 'index' either points to the range
	 * containing start position or to the insertion position
	 * for a new range.
	 * So first let's check if range I'm probing is here already.
	 */
	if (!inrange) {
requires_new_range:
		/*
		 * Range was not found.
		 * Insert at position 'index'
		 */
		used = run->count * sizeof(struct ntfs_run);

		/*
		 * Check allocated space.
		 * If one is not enough to get one more entry
		 * then it will be reallocated.
		 */
		if (run->allocated < used + sizeof(struct ntfs_run)) {
			size_t bytes;
			struct ntfs_run *new_ptr;

			/* Use power of 2 for 'bytes'. */
			if (!used) {
				bytes = 64;
			} else if (used <= 16 * PAGE_SIZE) {
				if (is_power_of_2(run->allocated))
					bytes = run->allocated << 1;
				else
					bytes = (size_t)1
						<< (2 + blksize_bits(used));
			} else {
				bytes = run->allocated + (16 * PAGE_SIZE);
			}

			WARN_ON(!is_mft && bytes > NTFS3_RUN_MAX_BYTES);

			new_ptr = kvmalloc(bytes, GFP_KERNEL);

			if (!new_ptr)
				return false;

			r = new_ptr + index;
			memcpy(new_ptr, run->runs,
			       index * sizeof(struct ntfs_run));
			memcpy(r + 1, run->runs + index,
			       sizeof(struct ntfs_run) * (run->count - index));

			kvfree(run->runs);
			run->runs = new_ptr;
			run->allocated = bytes;

		} else {
			size_t i = run->count - index;

			r = run->runs + index;

			/* memmove appears to be a bottle neck here... */
			if (i > 0)
				memmove(r + 1, r, sizeof(struct ntfs_run) * i);
		}

		r->vcn = vcn;
		r->lcn = lcn;
		r->len = len;
		run->count += 1;
	} else {
		r = run->runs + index;

		/*
		 * If one of ranges was not allocated then we
		 * have to split location we just matched and
		 * insert current one.
		 * A common case this requires tail to be reinserted
		 * a recursive call.
		 */
		if (((lcn == SPARSE_LCN) != (r->lcn == SPARSE_LCN)) ||
		    (lcn != SPARSE_LCN && lcn != r->lcn + (vcn - r->vcn))) {
			CLST to_eat = vcn - r->vcn;
			CLST Tovcn = to_eat + len;

			should_add_tail = Tovcn < r->len;

			if (should_add_tail) {
				tail_lcn = r->lcn == SPARSE_LCN
						   ? SPARSE_LCN
						   : (r->lcn + Tovcn);
				tail_vcn = r->vcn + Tovcn;
				tail_len = r->len - Tovcn;
			}

			if (to_eat > 0) {
				r->len = to_eat;
				inrange = false;
				index += 1;
				goto requires_new_range;
			}

			/* lcn should match one were going to add. */
			r->lcn = lcn;
		}

		/*
		 * If existing range fits then were done.
		 * Otherwise extend found one and fall back to range jocode.
		 */
		if (r->vcn + r->len < vcn + len)
			r->len += len - ((r->vcn + r->len) - vcn);
	}

	/*
	 * And normalize it starting from insertion point.
	 * It's possible that no insertion needed case if
	 * start point lies within the range of an entry
	 * that 'index' points to.
	 */
	if (inrange && index > 0)
		index -= 1;
	run_consolidate(run, index);
	run_consolidate(run, index + 1);

	/*
	 * A special case.
	 * We have to add extra range a tail.
	 */
	if (should_add_tail &&
	    !run_add_entry(run, tail_vcn, tail_lcn, tail_len, is_mft))
		return false;

	return true;
}

/* run_collapse_range
 *
 * Helper for attr_collapse_range(),
 * which is helper for fallocate(collapse_range).
 */
bool run_collapse_range(struct runs_tree *run, CLST vcn, CLST len)
{
	size_t index, eat;
	struct ntfs_run *r, *e, *eat_start, *eat_end;
	CLST end;

	if (WARN_ON(!run_lookup(run, vcn, &index)))
		return true; /* Should never be here. */

	e = run->runs + run->count;
	r = run->runs + index;
	end = vcn + len;

	if (vcn > r->vcn) {
		if (r->vcn + r->len <= end) {
			/* Collapse tail of run .*/
			r->len = vcn - r->vcn;
		} else if (r->lcn == SPARSE_LCN) {
			/* Collapse a middle part of sparsed run. */
			r->len -= len;
		} else {
			/* Collapse a middle part of normal run, split. */
			if (!run_add_entry(run, vcn, SPARSE_LCN, len, false))
				return false;
			return run_collapse_range(run, vcn, len);
		}

		r += 1;
	}

	eat_start = r;
	eat_end = r;

	for (; r < e; r++) {
		CLST d;

		if (r->vcn >= end) {
			r->vcn -= len;
			continue;
		}

		if (r->vcn + r->len <= end) {
			/* Eat this run. */
			eat_end = r + 1;
			continue;
		}

		d = end - r->vcn;
		if (r->lcn != SPARSE_LCN)
			r->lcn += d;
		r->len -= d;
		r->vcn -= len - d;
	}

	eat = eat_end - eat_start;
	memmove(eat_start, eat_end, (e - eat_end) * sizeof(*r));
	run->count -= eat;

	return true;
}

/* run_insert_range
 *
 * Helper for attr_insert_range(),
 * which is helper for fallocate(insert_range).
 */
bool run_insert_range(struct runs_tree *run, CLST vcn, CLST len)
{
	size_t index;
	struct ntfs_run *r, *e;

	if (WARN_ON(!run_lookup(run, vcn, &index)))
		return false; /* Should never be here. */

	e = run->runs + run->count;
	r = run->runs + index;

	if (vcn > r->vcn)
		r += 1;

	for (; r < e; r++)
		r->vcn += len;

	r = run->runs + index;

	if (vcn > r->vcn) {
		/* split fragment. */
		CLST len1 = vcn - r->vcn;
		CLST len2 = r->len - len1;
		CLST lcn2 = r->lcn == SPARSE_LCN ? SPARSE_LCN : (r->lcn + len1);

		r->len = len1;

		if (!run_add_entry(run, vcn + len, lcn2, len2, false))
			return false;
	}

	if (!run_add_entry(run, vcn, SPARSE_LCN, len, false))
		return false;

	return true;
}

/*
 * run_get_entry - Return index-th mapped region.
 */
bool run_get_entry(const struct runs_tree *run, size_t index, CLST *vcn,
		   CLST *lcn, CLST *len)
{
	const struct ntfs_run *r;

	if (index >= run->count)
		return false;

	r = run->runs + index;

	if (!r->len)
		return false;

	if (vcn)
		*vcn = r->vcn;
	if (lcn)
		*lcn = r->lcn;
	if (len)
		*len = r->len;
	return true;
}

/*
 * run_packed_size - Calculate the size of packed int64.
 */
#ifdef __BIG_ENDIAN
static inline int run_packed_size(const s64 n)
{
	const u8 *p = (const u8 *)&n + sizeof(n) - 1;

	if (n >= 0) {
		if (p[-7] || p[-6] || p[-5] || p[-4])
			p -= 4;
		if (p[-3] || p[-2])
			p -= 2;
		if (p[-1])
			p -= 1;
		if (p[0] & 0x80)
			p -= 1;
	} else {
		if (p[-7] != 0xff || p[-6] != 0xff || p[-5] != 0xff ||
		    p[-4] != 0xff)
			p -= 4;
		if (p[-3] != 0xff || p[-2] != 0xff)
			p -= 2;
		if (p[-1] != 0xff)
			p -= 1;
		if (!(p[0] & 0x80))
			p -= 1;
	}
	return (const u8 *)&n + sizeof(n) - p;
}

/* Full trusted function. It does not check 'size' for errors. */
static inline void run_pack_s64(u8 *run_buf, u8 size, s64 v)
{
	const u8 *p = (u8 *)&v;

	switch (size) {
	case 8:
		run_buf[7] = p[0];
		fallthrough;
	case 7:
		run_buf[6] = p[1];
		fallthrough;
	case 6:
		run_buf[5] = p[2];
		fallthrough;
	case 5:
		run_buf[4] = p[3];
		fallthrough;
	case 4:
		run_buf[3] = p[4];
		fallthrough;
	case 3:
		run_buf[2] = p[5];
		fallthrough;
	case 2:
		run_buf[1] = p[6];
		fallthrough;
	case 1:
		run_buf[0] = p[7];
	}
}

/* Full trusted function. It does not check 'size' for errors. */
static inline s64 run_unpack_s64(const u8 *run_buf, u8 size, s64 v)
{
	u8 *p = (u8 *)&v;

	switch (size) {
	case 8:
		p[0] = run_buf[7];
		fallthrough;
	case 7:
		p[1] = run_buf[6];
		fallthrough;
	case 6:
		p[2] = run_buf[5];
		fallthrough;
	case 5:
		p[3] = run_buf[4];
		fallthrough;
	case 4:
		p[4] = run_buf[3];
		fallthrough;
	case 3:
		p[5] = run_buf[2];
		fallthrough;
	case 2:
		p[6] = run_buf[1];
		fallthrough;
	case 1:
		p[7] = run_buf[0];
	}
	return v;
}

#else

static inline int run_packed_size(const s64 n)
{
	const u8 *p = (const u8 *)&n;

	if (n >= 0) {
		if (p[7] || p[6] || p[5] || p[4])
			p += 4;
		if (p[3] || p[2])
			p += 2;
		if (p[1])
			p += 1;
		if (p[0] & 0x80)
			p += 1;
	} else {
		if (p[7] != 0xff || p[6] != 0xff || p[5] != 0xff ||
		    p[4] != 0xff)
			p += 4;
		if (p[3] != 0xff || p[2] != 0xff)
			p += 2;
		if (p[1] != 0xff)
			p += 1;
		if (!(p[0] & 0x80))
			p += 1;
	}

	return 1 + p - (const u8 *)&n;
}

/* Full trusted function. It does not check 'size' for errors. */
static inline void run_pack_s64(u8 *run_buf, u8 size, s64 v)
{
	const u8 *p = (u8 *)&v;

	/* memcpy( run_buf, &v, size); Is it faster? */
	switch (size) {
	case 8:
		run_buf[7] = p[7];
		fallthrough;
	case 7:
		run_buf[6] = p[6];
		fallthrough;
	case 6:
		run_buf[5] = p[5];
		fallthrough;
	case 5:
		run_buf[4] = p[4];
		fallthrough;
	case 4:
		run_buf[3] = p[3];
		fallthrough;
	case 3:
		run_buf[2] = p[2];
		fallthrough;
	case 2:
		run_buf[1] = p[1];
		fallthrough;
	case 1:
		run_buf[0] = p[0];
	}
}

/* full trusted function. It does not check 'size' for errors */
static inline s64 run_unpack_s64(const u8 *run_buf, u8 size, s64 v)
{
	u8 *p = (u8 *)&v;

	/* memcpy( &v, run_buf, size); Is it faster? */
	switch (size) {
	case 8:
		p[7] = run_buf[7];
		fallthrough;
	case 7:
		p[6] = run_buf[6];
		fallthrough;
	case 6:
		p[5] = run_buf[5];
		fallthrough;
	case 5:
		p[4] = run_buf[4];
		fallthrough;
	case 4:
		p[3] = run_buf[3];
		fallthrough;
	case 3:
		p[2] = run_buf[2];
		fallthrough;
	case 2:
		p[1] = run_buf[1];
		fallthrough;
	case 1:
		p[0] = run_buf[0];
	}
	return v;
}
#endif

/*
 * run_pack - Pack runs into buffer.
 *
 * packed_vcns - How much runs we have packed.
 * packed_size - How much bytes we have used run_buf.
 */
int run_pack(const struct runs_tree *run, CLST svcn, CLST len, u8 *run_buf,
	     u32 run_buf_size, CLST *packed_vcns)
{
	CLST next_vcn, vcn, lcn;
	CLST prev_lcn = 0;
	CLST evcn1 = svcn + len;
	const struct ntfs_run *r, *r_end;
	int packed_size = 0;
	size_t i;
	s64 dlcn;
	int offset_size, size_size, tmp;

	*packed_vcns = 0;

	if (!len)
		goto out;

	/* Check all required entries [svcn, encv1) available. */
	if (!run_lookup(run, svcn, &i))
		return -ENOENT;

	r_end = run->runs + run->count;
	r = run->runs + i;

	for (next_vcn = r->vcn + r->len; next_vcn < evcn1;
	     next_vcn = r->vcn + r->len) {
		if (++r >= r_end || r->vcn != next_vcn)
			return -ENOENT;
	}

	/* Repeat cycle above and pack runs. Assume no errors. */
	r = run->runs + i;
	len = svcn - r->vcn;
	vcn = svcn;
	lcn = r->lcn == SPARSE_LCN ? SPARSE_LCN : (r->lcn + len);
	len = r->len - len;

	for (;;) {
		next_vcn = vcn + len;
		if (next_vcn > evcn1)
			len = evcn1 - vcn;

		/* How much bytes required to pack len. */
		size_size = run_packed_size(len);

		/* offset_size - How much bytes is packed dlcn. */
		if (lcn == SPARSE_LCN) {
			offset_size = 0;
			dlcn = 0;
		} else {
			/* NOTE: lcn can be less than prev_lcn! */
			dlcn = (s64)lcn - prev_lcn;
			offset_size = run_packed_size(dlcn);
			prev_lcn = lcn;
		}

		tmp = run_buf_size - packed_size - 2 - offset_size;
		if (tmp <= 0)
			goto out;

		/* Can we store this entire run. */
		if (tmp < size_size)
			goto out;

		if (run_buf) {
			/* Pack run header. */
			run_buf[0] = ((u8)(size_size | (offset_size << 4)));
			run_buf += 1;

			/* Pack the length of run. */
			run_pack_s64(run_buf, size_size, len);

			run_buf += size_size;
			/* Pack the offset from previous LCN. */
			run_pack_s64(run_buf, offset_size, dlcn);
			run_buf += offset_size;
		}

		packed_size += 1 + offset_size + size_size;
		*packed_vcns += len;

		if (packed_size + 1 >= run_buf_size || next_vcn >= evcn1)
			goto out;

		r += 1;
		vcn = r->vcn;
		lcn = r->lcn;
		len = r->len;
	}

out:
	/* Store last zero. */
	if (run_buf)
		run_buf[0] = 0;

	return packed_size + 1;
}

/*
 * run_unpack - Unpack packed runs from @run_buf.
 *
 * Return: Error if negative, or real used bytes.
 */
int run_unpack(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino,
	       CLST svcn, CLST evcn, CLST vcn, const u8 *run_buf,
	       int run_buf_size)
{
	u64 prev_lcn, vcn64, lcn, next_vcn;
	const u8 *run_last, *run_0;
	bool is_mft = ino == MFT_REC_MFT;

	if (run_buf_size < 0)
		return -EINVAL;

	/* Check for empty. */
	if (evcn + 1 == svcn)
		return 0;

	if (evcn < svcn)
		return -EINVAL;

	run_0 = run_buf;
	run_last = run_buf + run_buf_size;
	prev_lcn = 0;
	vcn64 = svcn;

	/* Read all runs the chain. */
	/* size_size - How much bytes is packed len. */
	while (run_buf < run_last) {
		/* size_size - How much bytes is packed len. */
		u8 size_size = *run_buf & 0xF;
		/* offset_size - How much bytes is packed dlcn. */
		u8 offset_size = *run_buf++ >> 4;
		u64 len;

		if (!size_size)
			break;

		/*
		 * Unpack runs.
		 * NOTE: Runs are stored little endian order
		 * "len" is unsigned value, "dlcn" is signed.
		 * Large positive number requires to store 5 bytes
		 * e.g.: 05 FF 7E FF FF 00 00 00
		 */
		if (size_size > 8)
			return -EINVAL;

		len = run_unpack_s64(run_buf, size_size, 0);
		/* Skip size_size. */
		run_buf += size_size;

		if (!len)
			return -EINVAL;

		if (!offset_size)
			lcn = SPARSE_LCN64;
		else if (offset_size <= 8) {
			s64 dlcn;

			/* Initial value of dlcn is -1 or 0. */
			dlcn = (run_buf[offset_size - 1] & 0x80) ? (s64)-1 : 0;
			dlcn = run_unpack_s64(run_buf, offset_size, dlcn);
			/* Skip offset_size. */
			run_buf += offset_size;

			if (!dlcn)
				return -EINVAL;
			lcn = prev_lcn + dlcn;
			prev_lcn = lcn;
		} else
			return -EINVAL;

		next_vcn = vcn64 + len;
		/* Check boundary. */
		if (next_vcn > evcn + 1)
			return -EINVAL;

#ifndef CONFIG_NTFS3_64BIT_CLUSTER
		if (next_vcn > 0x100000000ull || (lcn + len) > 0x100000000ull) {
			ntfs_err(
				sbi->sb,
				"This driver is compiled without CONFIG_NTFS3_64BIT_CLUSTER (like windows driver).\n"
				"Volume contains 64 bits run: vcn %llx, lcn %llx, len %llx.\n"
				"Activate CONFIG_NTFS3_64BIT_CLUSTER to process this case",
				vcn64, lcn, len);
			return -EOPNOTSUPP;
		}
#endif
		if (lcn != SPARSE_LCN64 && lcn + len > sbi->used.bitmap.nbits) {
			/* LCN range is out of volume. */
			return -EINVAL;
		}

		if (!run)
			; /* Called from check_attr(fslog.c) to check run. */
		else if (run == RUN_DEALLOCATE) {
			/*
			 * Called from ni_delete_all to free clusters
			 * without storing in run.
			 */
			if (lcn != SPARSE_LCN64)
				mark_as_free_ex(sbi, lcn, len, true);
		} else if (vcn64 >= vcn) {
			if (!run_add_entry(run, vcn64, lcn, len, is_mft))
				return -ENOMEM;
		} else if (next_vcn > vcn) {
			u64 dlen = vcn - vcn64;

			if (!run_add_entry(run, vcn, lcn + dlen, len - dlen,
					   is_mft))
				return -ENOMEM;
		}

		vcn64 = next_vcn;
	}

	if (vcn64 != evcn + 1) {
		/* Not expected length of unpacked runs. */
		return -EINVAL;
	}

	return run_buf - run_0;
}

#ifdef NTFS3_CHECK_FREE_CLST
/*
 * run_unpack_ex - Unpack packed runs from "run_buf".
 *
 * Checks unpacked runs to be used in bitmap.
 *
 * Return: Error if negative, or real used bytes.
 */
int run_unpack_ex(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino,
		  CLST svcn, CLST evcn, CLST vcn, const u8 *run_buf,
		  int run_buf_size)
{
	int ret, err;
	CLST next_vcn, lcn, len;
	size_t index;
	bool ok;
	struct wnd_bitmap *wnd;

	ret = run_unpack(run, sbi, ino, svcn, evcn, vcn, run_buf, run_buf_size);
	if (ret <= 0)
		return ret;

	if (!sbi->used.bitmap.sb || !run || run == RUN_DEALLOCATE)
		return ret;

	if (ino == MFT_REC_BADCLUST)
		return ret;

	next_vcn = vcn = svcn;
	wnd = &sbi->used.bitmap;

	for (ok = run_lookup_entry(run, vcn, &lcn, &len, &index);
	     next_vcn <= evcn;
	     ok = run_get_entry(run, ++index, &vcn, &lcn, &len)) {
		if (!ok || next_vcn != vcn)
			return -EINVAL;

		next_vcn = vcn + len;

		if (lcn == SPARSE_LCN)
			continue;

		if (sbi->flags & NTFS_FLAGS_NEED_REPLAY)
			continue;

		down_read_nested(&wnd->rw_lock, BITMAP_MUTEX_CLUSTERS);
		/* Check for free blocks. */
		ok = wnd_is_used(wnd, lcn, len);
		up_read(&wnd->rw_lock);
		if (ok)
			continue;

		/* Looks like volume is corrupted. */
		ntfs_set_state(sbi, NTFS_DIRTY_ERROR);

		if (down_write_trylock(&wnd->rw_lock)) {
			/* Mark all zero bits as used in range [lcn, lcn+len). */
			CLST i, lcn_f = 0, len_f = 0;

			err = 0;
			for (i = 0; i < len; i++) {
				if (wnd_is_free(wnd, lcn + i, 1)) {
					if (!len_f)
						lcn_f = lcn + i;
					len_f += 1;
				} else if (len_f) {
					err = wnd_set_used(wnd, lcn_f, len_f);
					len_f = 0;
					if (err)
						break;
				}
			}

			if (len_f)
				err = wnd_set_used(wnd, lcn_f, len_f);

			up_write(&wnd->rw_lock);
			if (err)
				return err;
		}
	}

	return ret;
}
#endif

/*
 * run_get_highest_vcn
 *
 * Return the highest vcn from a mapping pairs array
 * it used while replaying log file.
 */
int run_get_highest_vcn(CLST vcn, const u8 *run_buf, u64 *highest_vcn)
{
	u64 vcn64 = vcn;
	u8 size_size;

	while ((size_size = *run_buf & 0xF)) {
		u8 offset_size = *run_buf++ >> 4;
		u64 len;

		if (size_size > 8 || offset_size > 8)
			return -EINVAL;

		len = run_unpack_s64(run_buf, size_size, 0);
		if (!len)
			return -EINVAL;

		run_buf += size_size + offset_size;
		vcn64 += len;

#ifndef CONFIG_NTFS3_64BIT_CLUSTER
		if (vcn64 > 0x100000000ull)
			return -EINVAL;
#endif
	}

	*highest_vcn = vcn64 - 1;
	return 0;
}

/*
 * run_clone
 *
 * Make a copy of run
 */
int run_clone(const struct runs_tree *run, struct runs_tree *new_run)
{
	size_t bytes = run->count * sizeof(struct ntfs_run);

	if (bytes > new_run->allocated) {
		struct ntfs_run *new_ptr = kvmalloc(bytes, GFP_KERNEL);

		if (!new_ptr)
			return -ENOMEM;

		kvfree(new_run->runs);
		new_run->runs = new_ptr;
		new_run->allocated = bytes;
	}

	memcpy(new_run->runs, run->runs, bytes);
	new_run->count = run->count;
	return 0;
}