summaryrefslogtreecommitdiff
path: root/drivers/md/persistent-data/dm-space-map-common.c
blob: fd4cea718e68037c9c0615b260b9044def490669 (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011 Red Hat, Inc.
 *
 * This file is released under the GPL.
 */

#include "dm-space-map-common.h"
#include "dm-transaction-manager.h"
#include "dm-btree-internal.h"
#include "dm-persistent-data-internal.h"

#include <linux/bitops.h>
#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "space map common"

/*----------------------------------------------------------------*/

/*
 * Index validator.
 */
#define INDEX_CSUM_XOR 160478

static void index_prepare_for_write(struct dm_block_validator *v,
				    struct dm_block *b,
				    size_t block_size)
{
	struct disk_metadata_index *mi_le = dm_block_data(b);

	mi_le->blocknr = cpu_to_le64(dm_block_location(b));
	mi_le->csum = cpu_to_le32(dm_bm_checksum(&mi_le->padding,
						 block_size - sizeof(__le32),
						 INDEX_CSUM_XOR));
}

static int index_check(struct dm_block_validator *v,
		       struct dm_block *b,
		       size_t block_size)
{
	struct disk_metadata_index *mi_le = dm_block_data(b);
	__le32 csum_disk;

	if (dm_block_location(b) != le64_to_cpu(mi_le->blocknr)) {
		DMERR_LIMIT("index_check failed: blocknr %llu != wanted %llu",
			    le64_to_cpu(mi_le->blocknr), dm_block_location(b));
		return -ENOTBLK;
	}

	csum_disk = cpu_to_le32(dm_bm_checksum(&mi_le->padding,
					       block_size - sizeof(__le32),
					       INDEX_CSUM_XOR));
	if (csum_disk != mi_le->csum) {
		DMERR_LIMIT("index_check failed: csum %u != wanted %u",
			    le32_to_cpu(csum_disk), le32_to_cpu(mi_le->csum));
		return -EILSEQ;
	}

	return 0;
}

static struct dm_block_validator index_validator = {
	.name = "index",
	.prepare_for_write = index_prepare_for_write,
	.check = index_check
};

/*----------------------------------------------------------------*/

/*
 * Bitmap validator
 */
#define BITMAP_CSUM_XOR 240779

static void dm_bitmap_prepare_for_write(struct dm_block_validator *v,
					struct dm_block *b,
					size_t block_size)
{
	struct disk_bitmap_header *disk_header = dm_block_data(b);

	disk_header->blocknr = cpu_to_le64(dm_block_location(b));
	disk_header->csum = cpu_to_le32(dm_bm_checksum(&disk_header->not_used,
						       block_size - sizeof(__le32),
						       BITMAP_CSUM_XOR));
}

static int dm_bitmap_check(struct dm_block_validator *v,
			   struct dm_block *b,
			   size_t block_size)
{
	struct disk_bitmap_header *disk_header = dm_block_data(b);
	__le32 csum_disk;

	if (dm_block_location(b) != le64_to_cpu(disk_header->blocknr)) {
		DMERR_LIMIT("bitmap check failed: blocknr %llu != wanted %llu",
			    le64_to_cpu(disk_header->blocknr), dm_block_location(b));
		return -ENOTBLK;
	}

	csum_disk = cpu_to_le32(dm_bm_checksum(&disk_header->not_used,
					       block_size - sizeof(__le32),
					       BITMAP_CSUM_XOR));
	if (csum_disk != disk_header->csum) {
		DMERR_LIMIT("bitmap check failed: csum %u != wanted %u",
			    le32_to_cpu(csum_disk), le32_to_cpu(disk_header->csum));
		return -EILSEQ;
	}

	return 0;
}

static struct dm_block_validator dm_sm_bitmap_validator = {
	.name = "sm_bitmap",
	.prepare_for_write = dm_bitmap_prepare_for_write,
	.check = dm_bitmap_check,
};

/*----------------------------------------------------------------*/

#define ENTRIES_PER_WORD 32
#define ENTRIES_SHIFT	5

static void *dm_bitmap_data(struct dm_block *b)
{
	return dm_block_data(b) + sizeof(struct disk_bitmap_header);
}

#define WORD_MASK_HIGH 0xAAAAAAAAAAAAAAAAULL

static unsigned int dm_bitmap_word_used(void *addr, unsigned int b)
{
	__le64 *words_le = addr;
	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);

	uint64_t bits = le64_to_cpu(*w_le);
	uint64_t mask = (bits + WORD_MASK_HIGH + 1) & WORD_MASK_HIGH;

	return !(~bits & mask);
}

static unsigned int sm_lookup_bitmap(void *addr, unsigned int b)
{
	__le64 *words_le = addr;
	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);
	unsigned int hi, lo;

	b = (b & (ENTRIES_PER_WORD - 1)) << 1;
	hi = !!test_bit_le(b, (void *) w_le);
	lo = !!test_bit_le(b + 1, (void *) w_le);
	return (hi << 1) | lo;
}

static void sm_set_bitmap(void *addr, unsigned int b, unsigned int val)
{
	__le64 *words_le = addr;
	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);

	b = (b & (ENTRIES_PER_WORD - 1)) << 1;

	if (val & 2)
		__set_bit_le(b, (void *) w_le);
	else
		__clear_bit_le(b, (void *) w_le);

	if (val & 1)
		__set_bit_le(b + 1, (void *) w_le);
	else
		__clear_bit_le(b + 1, (void *) w_le);
}

static int sm_find_free(void *addr, unsigned int begin, unsigned int end,
			unsigned int *result)
{
	while (begin < end) {
		if (!(begin & (ENTRIES_PER_WORD - 1)) &&
		    dm_bitmap_word_used(addr, begin)) {
			begin += ENTRIES_PER_WORD;
			continue;
		}

		if (!sm_lookup_bitmap(addr, begin)) {
			*result = begin;
			return 0;
		}

		begin++;
	}

	return -ENOSPC;
}

/*----------------------------------------------------------------*/

static int sm_ll_init(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
	memset(ll, 0, sizeof(struct ll_disk));

	ll->tm = tm;

	ll->bitmap_info.tm = tm;
	ll->bitmap_info.levels = 1;

	/*
	 * Because the new bitmap blocks are created via a shadow
	 * operation, the old entry has already had its reference count
	 * decremented and we don't need the btree to do any bookkeeping.
	 */
	ll->bitmap_info.value_type.size = sizeof(struct disk_index_entry);
	ll->bitmap_info.value_type.inc = NULL;
	ll->bitmap_info.value_type.dec = NULL;
	ll->bitmap_info.value_type.equal = NULL;

	ll->ref_count_info.tm = tm;
	ll->ref_count_info.levels = 1;
	ll->ref_count_info.value_type.size = sizeof(uint32_t);
	ll->ref_count_info.value_type.inc = NULL;
	ll->ref_count_info.value_type.dec = NULL;
	ll->ref_count_info.value_type.equal = NULL;

	ll->block_size = dm_bm_block_size(dm_tm_get_bm(tm));

	if (ll->block_size > (1 << 30)) {
		DMERR("block size too big to hold bitmaps");
		return -EINVAL;
	}

	ll->entries_per_block = (ll->block_size - sizeof(struct disk_bitmap_header)) *
		ENTRIES_PER_BYTE;
	ll->nr_blocks = 0;
	ll->bitmap_root = 0;
	ll->ref_count_root = 0;
	ll->bitmap_index_changed = false;

	return 0;
}

int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks)
{
	int r;
	dm_block_t i, nr_blocks, nr_indexes;
	unsigned int old_blocks, blocks;

	nr_blocks = ll->nr_blocks + extra_blocks;
	old_blocks = dm_sector_div_up(ll->nr_blocks, ll->entries_per_block);
	blocks = dm_sector_div_up(nr_blocks, ll->entries_per_block);

	nr_indexes = dm_sector_div_up(nr_blocks, ll->entries_per_block);
	if (nr_indexes > ll->max_entries(ll)) {
		DMERR("space map too large");
		return -EINVAL;
	}

	/*
	 * We need to set this before the dm_tm_new_block() call below.
	 */
	ll->nr_blocks = nr_blocks;
	for (i = old_blocks; i < blocks; i++) {
		struct dm_block *b;
		struct disk_index_entry idx;

		r = dm_tm_new_block(ll->tm, &dm_sm_bitmap_validator, &b);
		if (r < 0)
			return r;

		idx.blocknr = cpu_to_le64(dm_block_location(b));

		dm_tm_unlock(ll->tm, b);

		idx.nr_free = cpu_to_le32(ll->entries_per_block);
		idx.none_free_before = 0;

		r = ll->save_ie(ll, i, &idx);
		if (r < 0)
			return r;
	}

	return 0;
}

int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result)
{
	int r;
	dm_block_t index = b;
	struct disk_index_entry ie_disk;
	struct dm_block *blk;

	if (b >= ll->nr_blocks) {
		DMERR_LIMIT("metadata block out of bounds");
		return -EINVAL;
	}

	b = do_div(index, ll->entries_per_block);
	r = ll->load_ie(ll, index, &ie_disk);
	if (r < 0)
		return r;

	r = dm_tm_read_lock(ll->tm, le64_to_cpu(ie_disk.blocknr),
			    &dm_sm_bitmap_validator, &blk);
	if (r < 0)
		return r;

	*result = sm_lookup_bitmap(dm_bitmap_data(blk), b);

	dm_tm_unlock(ll->tm, blk);

	return 0;
}

static int sm_ll_lookup_big_ref_count(struct ll_disk *ll, dm_block_t b,
				      uint32_t *result)
{
	__le32 le_rc;
	int r;

	r = dm_btree_lookup(&ll->ref_count_info, ll->ref_count_root, &b, &le_rc);
	if (r < 0)
		return r;

	*result = le32_to_cpu(le_rc);

	return r;
}

int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result)
{
	int r = sm_ll_lookup_bitmap(ll, b, result);

	if (r)
		return r;

	if (*result != 3)
		return r;

	return sm_ll_lookup_big_ref_count(ll, b, result);
}

int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
			  dm_block_t end, dm_block_t *result)
{
	int r;
	struct disk_index_entry ie_disk;
	dm_block_t i, index_begin = begin;
	dm_block_t index_end = dm_sector_div_up(end, ll->entries_per_block);

	/*
	 * FIXME: Use shifts
	 */
	begin = do_div(index_begin, ll->entries_per_block);
	end = do_div(end, ll->entries_per_block);
	if (end == 0)
		end = ll->entries_per_block;

	for (i = index_begin; i < index_end; i++, begin = 0) {
		struct dm_block *blk;
		unsigned int position;
		uint32_t bit_end;

		r = ll->load_ie(ll, i, &ie_disk);
		if (r < 0)
			return r;

		if (le32_to_cpu(ie_disk.nr_free) == 0)
			continue;

		r = dm_tm_read_lock(ll->tm, le64_to_cpu(ie_disk.blocknr),
				    &dm_sm_bitmap_validator, &blk);
		if (r < 0)
			return r;

		bit_end = (i == index_end - 1) ?  end : ll->entries_per_block;

		r = sm_find_free(dm_bitmap_data(blk),
				 max_t(unsigned int, begin, le32_to_cpu(ie_disk.none_free_before)),
				 bit_end, &position);
		if (r == -ENOSPC) {
			/*
			 * This might happen because we started searching
			 * part way through the bitmap.
			 */
			dm_tm_unlock(ll->tm, blk);
			continue;
		}

		dm_tm_unlock(ll->tm, blk);

		*result = i * ll->entries_per_block + (dm_block_t) position;
		return 0;
	}

	return -ENOSPC;
}

int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
				 dm_block_t begin, dm_block_t end, dm_block_t *b)
{
	int r;
	uint32_t count;

	do {
		r = sm_ll_find_free_block(new_ll, begin, new_ll->nr_blocks, b);
		if (r)
			break;

		/* double check this block wasn't used in the old transaction */
		if (*b >= old_ll->nr_blocks)
			count = 0;
		else {
			r = sm_ll_lookup(old_ll, *b, &count);
			if (r)
				break;

			if (count)
				begin = *b + 1;
		}
	} while (count);

	return r;
}

/*----------------------------------------------------------------*/

int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
		 uint32_t ref_count, int32_t *nr_allocations)
{
	int r;
	uint32_t bit, old;
	struct dm_block *nb;
	dm_block_t index = b;
	struct disk_index_entry ie_disk;
	void *bm_le;
	int inc;

	bit = do_div(index, ll->entries_per_block);
	r = ll->load_ie(ll, index, &ie_disk);
	if (r < 0)
		return r;

	r = dm_tm_shadow_block(ll->tm, le64_to_cpu(ie_disk.blocknr),
			       &dm_sm_bitmap_validator, &nb, &inc);
	if (r < 0) {
		DMERR("dm_tm_shadow_block() failed");
		return r;
	}
	ie_disk.blocknr = cpu_to_le64(dm_block_location(nb));
	bm_le = dm_bitmap_data(nb);

	old = sm_lookup_bitmap(bm_le, bit);
	if (old > 2) {
		r = sm_ll_lookup_big_ref_count(ll, b, &old);
		if (r < 0) {
			dm_tm_unlock(ll->tm, nb);
			return r;
		}
	}

	if (r) {
		dm_tm_unlock(ll->tm, nb);
		return r;
	}

	if (ref_count <= 2) {
		sm_set_bitmap(bm_le, bit, ref_count);
		dm_tm_unlock(ll->tm, nb);

		if (old > 2) {
			r = dm_btree_remove(&ll->ref_count_info,
					    ll->ref_count_root,
					    &b, &ll->ref_count_root);
			if (r)
				return r;
		}

	} else {
		__le32 le_rc = cpu_to_le32(ref_count);

		sm_set_bitmap(bm_le, bit, 3);
		dm_tm_unlock(ll->tm, nb);

		__dm_bless_for_disk(&le_rc);
		r = dm_btree_insert(&ll->ref_count_info, ll->ref_count_root,
				    &b, &le_rc, &ll->ref_count_root);
		if (r < 0) {
			DMERR("ref count insert failed");
			return r;
		}
	}

	if (ref_count && !old) {
		*nr_allocations = 1;
		ll->nr_allocated++;
		le32_add_cpu(&ie_disk.nr_free, -1);
		if (le32_to_cpu(ie_disk.none_free_before) == bit)
			ie_disk.none_free_before = cpu_to_le32(bit + 1);

	} else if (old && !ref_count) {
		*nr_allocations = -1;
		ll->nr_allocated--;
		le32_add_cpu(&ie_disk.nr_free, 1);
		ie_disk.none_free_before = cpu_to_le32(min(le32_to_cpu(ie_disk.none_free_before), bit));
	} else
		*nr_allocations = 0;

	return ll->save_ie(ll, index, &ie_disk);
}

/*----------------------------------------------------------------*/

/*
 * Holds useful intermediate results for the range based inc and dec
 * operations.
 */
struct inc_context {
	struct disk_index_entry ie_disk;
	struct dm_block *bitmap_block;
	void *bitmap;

	struct dm_block *overflow_leaf;
};

static inline void init_inc_context(struct inc_context *ic)
{
	ic->bitmap_block = NULL;
	ic->bitmap = NULL;
	ic->overflow_leaf = NULL;
}

static inline void exit_inc_context(struct ll_disk *ll, struct inc_context *ic)
{
	if (ic->bitmap_block)
		dm_tm_unlock(ll->tm, ic->bitmap_block);
	if (ic->overflow_leaf)
		dm_tm_unlock(ll->tm, ic->overflow_leaf);
}

static inline void reset_inc_context(struct ll_disk *ll, struct inc_context *ic)
{
	exit_inc_context(ll, ic);
	init_inc_context(ic);
}

/*
 * Confirms a btree node contains a particular key at an index.
 */
static bool contains_key(struct btree_node *n, uint64_t key, int index)
{
	return index >= 0 &&
		index < le32_to_cpu(n->header.nr_entries) &&
		le64_to_cpu(n->keys[index]) == key;
}

static int __sm_ll_inc_overflow(struct ll_disk *ll, dm_block_t b, struct inc_context *ic)
{
	int r;
	int index;
	struct btree_node *n;
	__le32 *v_ptr;
	uint32_t rc;

	/*
	 * bitmap_block needs to be unlocked because getting the
	 * overflow_leaf may need to allocate, and thus use the space map.
	 */
	reset_inc_context(ll, ic);

	r = btree_get_overwrite_leaf(&ll->ref_count_info, ll->ref_count_root,
				     b, &index, &ll->ref_count_root, &ic->overflow_leaf);
	if (r < 0)
		return r;

	n = dm_block_data(ic->overflow_leaf);

	if (!contains_key(n, b, index)) {
		DMERR("overflow btree is missing an entry");
		return -EINVAL;
	}

	v_ptr = value_ptr(n, index);
	rc = le32_to_cpu(*v_ptr) + 1;
	*v_ptr = cpu_to_le32(rc);

	return 0;
}

static int sm_ll_inc_overflow(struct ll_disk *ll, dm_block_t b, struct inc_context *ic)
{
	int index;
	struct btree_node *n;
	__le32 *v_ptr;
	uint32_t rc;

	/*
	 * Do we already have the correct overflow leaf?
	 */
	if (ic->overflow_leaf) {
		n = dm_block_data(ic->overflow_leaf);
		index = lower_bound(n, b);
		if (contains_key(n, b, index)) {
			v_ptr = value_ptr(n, index);
			rc = le32_to_cpu(*v_ptr) + 1;
			*v_ptr = cpu_to_le32(rc);

			return 0;
		}
	}

	return __sm_ll_inc_overflow(ll, b, ic);
}

static inline int shadow_bitmap(struct ll_disk *ll, struct inc_context *ic)
{
	int r, inc;

	r = dm_tm_shadow_block(ll->tm, le64_to_cpu(ic->ie_disk.blocknr),
			       &dm_sm_bitmap_validator, &ic->bitmap_block, &inc);
	if (r < 0) {
		DMERR("dm_tm_shadow_block() failed");
		return r;
	}
	ic->ie_disk.blocknr = cpu_to_le64(dm_block_location(ic->bitmap_block));
	ic->bitmap = dm_bitmap_data(ic->bitmap_block);
	return 0;
}

/*
 * Once shadow_bitmap has been called, which always happens at the start of inc/dec,
 * we can reopen the bitmap with a simple write lock, rather than re calling
 * dm_tm_shadow_block().
 */
static inline int ensure_bitmap(struct ll_disk *ll, struct inc_context *ic)
{
	if (!ic->bitmap_block) {
		int r = dm_bm_write_lock(dm_tm_get_bm(ll->tm), le64_to_cpu(ic->ie_disk.blocknr),
					 &dm_sm_bitmap_validator, &ic->bitmap_block);
		if (r) {
			DMERR("unable to re-get write lock for bitmap");
			return r;
		}
		ic->bitmap = dm_bitmap_data(ic->bitmap_block);
	}

	return 0;
}

/*
 * Loops round incrementing entries in a single bitmap.
 */
static inline int sm_ll_inc_bitmap(struct ll_disk *ll, dm_block_t b,
				   uint32_t bit, uint32_t bit_end,
				   int32_t *nr_allocations, dm_block_t *new_b,
				   struct inc_context *ic)
{
	int r;
	__le32 le_rc;
	uint32_t old;

	for (; bit != bit_end; bit++, b++) {
		/*
		 * We only need to drop the bitmap if we need to find a new btree
		 * leaf for the overflow.  So if it was dropped last iteration,
		 * we now re-get it.
		 */
		r = ensure_bitmap(ll, ic);
		if (r)
			return r;

		old = sm_lookup_bitmap(ic->bitmap, bit);
		switch (old) {
		case 0:
			/* inc bitmap, adjust nr_allocated */
			sm_set_bitmap(ic->bitmap, bit, 1);
			(*nr_allocations)++;
			ll->nr_allocated++;
			le32_add_cpu(&ic->ie_disk.nr_free, -1);
			if (le32_to_cpu(ic->ie_disk.none_free_before) == bit)
				ic->ie_disk.none_free_before = cpu_to_le32(bit + 1);
			break;

		case 1:
			/* inc bitmap */
			sm_set_bitmap(ic->bitmap, bit, 2);
			break;

		case 2:
			/* inc bitmap and insert into overflow */
			sm_set_bitmap(ic->bitmap, bit, 3);
			reset_inc_context(ll, ic);

			le_rc = cpu_to_le32(3);
			__dm_bless_for_disk(&le_rc);
			r = dm_btree_insert(&ll->ref_count_info, ll->ref_count_root,
					    &b, &le_rc, &ll->ref_count_root);
			if (r < 0) {
				DMERR("ref count insert failed");
				return r;
			}
			break;

		default:
			/*
			 * inc within the overflow tree only.
			 */
			r = sm_ll_inc_overflow(ll, b, ic);
			if (r < 0)
				return r;
		}
	}

	*new_b = b;
	return 0;
}

/*
 * Finds a bitmap that contains entries in the block range, and increments
 * them.
 */
static int __sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e,
		       int32_t *nr_allocations, dm_block_t *new_b)
{
	int r;
	struct inc_context ic;
	uint32_t bit, bit_end;
	dm_block_t index = b;

	init_inc_context(&ic);

	bit = do_div(index, ll->entries_per_block);
	r = ll->load_ie(ll, index, &ic.ie_disk);
	if (r < 0)
		return r;

	r = shadow_bitmap(ll, &ic);
	if (r)
		return r;

	bit_end = min(bit + (e - b), (dm_block_t) ll->entries_per_block);
	r = sm_ll_inc_bitmap(ll, b, bit, bit_end, nr_allocations, new_b, &ic);

	exit_inc_context(ll, &ic);

	if (r)
		return r;

	return ll->save_ie(ll, index, &ic.ie_disk);
}

int sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e,
	      int32_t *nr_allocations)
{
	*nr_allocations = 0;
	while (b != e) {
		int r = __sm_ll_inc(ll, b, e, nr_allocations, &b);

		if (r)
			return r;
	}

	return 0;
}

/*----------------------------------------------------------------*/

static int __sm_ll_del_overflow(struct ll_disk *ll, dm_block_t b,
				struct inc_context *ic)
{
	reset_inc_context(ll, ic);
	return dm_btree_remove(&ll->ref_count_info, ll->ref_count_root,
			       &b, &ll->ref_count_root);
}

static int __sm_ll_dec_overflow(struct ll_disk *ll, dm_block_t b,
				struct inc_context *ic, uint32_t *old_rc)
{
	int r;
	int index = -1;
	struct btree_node *n;
	__le32 *v_ptr;
	uint32_t rc;

	reset_inc_context(ll, ic);
	r = btree_get_overwrite_leaf(&ll->ref_count_info, ll->ref_count_root,
				     b, &index, &ll->ref_count_root, &ic->overflow_leaf);
	if (r < 0)
		return r;

	n = dm_block_data(ic->overflow_leaf);

	if (!contains_key(n, b, index)) {
		DMERR("overflow btree is missing an entry");
		return -EINVAL;
	}

	v_ptr = value_ptr(n, index);
	rc = le32_to_cpu(*v_ptr);
	*old_rc = rc;

	if (rc == 3) {
		return __sm_ll_del_overflow(ll, b, ic);
	} else {
		rc--;
		*v_ptr = cpu_to_le32(rc);
		return 0;
	}
}

static int sm_ll_dec_overflow(struct ll_disk *ll, dm_block_t b,
			      struct inc_context *ic, uint32_t *old_rc)
{
	/*
	 * Do we already have the correct overflow leaf?
	 */
	if (ic->overflow_leaf) {
		int index;
		struct btree_node *n;
		__le32 *v_ptr;
		uint32_t rc;

		n = dm_block_data(ic->overflow_leaf);
		index = lower_bound(n, b);
		if (contains_key(n, b, index)) {
			v_ptr = value_ptr(n, index);
			rc = le32_to_cpu(*v_ptr);
			*old_rc = rc;

			if (rc > 3) {
				rc--;
				*v_ptr = cpu_to_le32(rc);
				return 0;
			} else {
				return __sm_ll_del_overflow(ll, b, ic);
			}

		}
	}

	return __sm_ll_dec_overflow(ll, b, ic, old_rc);
}

/*
 * Loops round incrementing entries in a single bitmap.
 */
static inline int sm_ll_dec_bitmap(struct ll_disk *ll, dm_block_t b,
				   uint32_t bit, uint32_t bit_end,
				   struct inc_context *ic,
				   int32_t *nr_allocations, dm_block_t *new_b)
{
	int r;
	uint32_t old;

	for (; bit != bit_end; bit++, b++) {
		/*
		 * We only need to drop the bitmap if we need to find a new btree
		 * leaf for the overflow.  So if it was dropped last iteration,
		 * we now re-get it.
		 */
		r = ensure_bitmap(ll, ic);
		if (r)
			return r;

		old = sm_lookup_bitmap(ic->bitmap, bit);
		switch (old) {
		case 0:
			DMERR("unable to decrement block");
			return -EINVAL;

		case 1:
			/* dec bitmap */
			sm_set_bitmap(ic->bitmap, bit, 0);
			(*nr_allocations)--;
			ll->nr_allocated--;
			le32_add_cpu(&ic->ie_disk.nr_free, 1);
			ic->ie_disk.none_free_before =
				cpu_to_le32(min(le32_to_cpu(ic->ie_disk.none_free_before), bit));
			break;

		case 2:
			/* dec bitmap and insert into overflow */
			sm_set_bitmap(ic->bitmap, bit, 1);
			break;

		case 3:
			r = sm_ll_dec_overflow(ll, b, ic, &old);
			if (r < 0)
				return r;

			if (old == 3) {
				r = ensure_bitmap(ll, ic);
				if (r)
					return r;

				sm_set_bitmap(ic->bitmap, bit, 2);
			}
			break;
		}
	}

	*new_b = b;
	return 0;
}

static int __sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e,
		       int32_t *nr_allocations, dm_block_t *new_b)
{
	int r;
	uint32_t bit, bit_end;
	struct inc_context ic;
	dm_block_t index = b;

	init_inc_context(&ic);

	bit = do_div(index, ll->entries_per_block);
	r = ll->load_ie(ll, index, &ic.ie_disk);
	if (r < 0)
		return r;

	r = shadow_bitmap(ll, &ic);
	if (r)
		return r;

	bit_end = min(bit + (e - b), (dm_block_t) ll->entries_per_block);
	r = sm_ll_dec_bitmap(ll, b, bit, bit_end, &ic, nr_allocations, new_b);
	exit_inc_context(ll, &ic);

	if (r)
		return r;

	return ll->save_ie(ll, index, &ic.ie_disk);
}

int sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e,
	      int32_t *nr_allocations)
{
	*nr_allocations = 0;
	while (b != e) {
		int r = __sm_ll_dec(ll, b, e, nr_allocations, &b);

		if (r)
			return r;
	}

	return 0;
}

/*----------------------------------------------------------------*/

int sm_ll_commit(struct ll_disk *ll)
{
	int r = 0;

	if (ll->bitmap_index_changed) {
		r = ll->commit(ll);
		if (!r)
			ll->bitmap_index_changed = false;
	}

	return r;
}

/*----------------------------------------------------------------*/

static int metadata_ll_load_ie(struct ll_disk *ll, dm_block_t index,
			       struct disk_index_entry *ie)
{
	memcpy(ie, ll->mi_le.index + index, sizeof(*ie));
	return 0;
}

static int metadata_ll_save_ie(struct ll_disk *ll, dm_block_t index,
			       struct disk_index_entry *ie)
{
	ll->bitmap_index_changed = true;
	memcpy(ll->mi_le.index + index, ie, sizeof(*ie));
	return 0;
}

static int metadata_ll_init_index(struct ll_disk *ll)
{
	int r;
	struct dm_block *b;

	r = dm_tm_new_block(ll->tm, &index_validator, &b);
	if (r < 0)
		return r;

	ll->bitmap_root = dm_block_location(b);

	dm_tm_unlock(ll->tm, b);

	return 0;
}

static int metadata_ll_open(struct ll_disk *ll)
{
	int r;
	struct dm_block *block;

	r = dm_tm_read_lock(ll->tm, ll->bitmap_root,
			    &index_validator, &block);
	if (r)
		return r;

	memcpy(&ll->mi_le, dm_block_data(block), sizeof(ll->mi_le));
	dm_tm_unlock(ll->tm, block);

	return 0;
}

static dm_block_t metadata_ll_max_entries(struct ll_disk *ll)
{
	return MAX_METADATA_BITMAPS;
}

static int metadata_ll_commit(struct ll_disk *ll)
{
	int r, inc;
	struct dm_block *b;

	r = dm_tm_shadow_block(ll->tm, ll->bitmap_root, &index_validator, &b, &inc);
	if (r)
		return r;

	memcpy(dm_block_data(b), &ll->mi_le, sizeof(ll->mi_le));
	ll->bitmap_root = dm_block_location(b);

	dm_tm_unlock(ll->tm, b);

	return 0;
}

int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
	int r;

	r = sm_ll_init(ll, tm);
	if (r < 0)
		return r;

	ll->load_ie = metadata_ll_load_ie;
	ll->save_ie = metadata_ll_save_ie;
	ll->init_index = metadata_ll_init_index;
	ll->open_index = metadata_ll_open;
	ll->max_entries = metadata_ll_max_entries;
	ll->commit = metadata_ll_commit;

	ll->nr_blocks = 0;
	ll->nr_allocated = 0;

	r = ll->init_index(ll);
	if (r < 0)
		return r;

	r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
	if (r < 0)
		return r;

	return 0;
}

int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
			void *root_le, size_t len)
{
	int r;
	struct disk_sm_root smr;

	if (len < sizeof(struct disk_sm_root)) {
		DMERR("sm_metadata root too small");
		return -ENOMEM;
	}

	/*
	 * We don't know the alignment of the root_le buffer, so need to
	 * copy into a new structure.
	 */
	memcpy(&smr, root_le, sizeof(smr));

	r = sm_ll_init(ll, tm);
	if (r < 0)
		return r;

	ll->load_ie = metadata_ll_load_ie;
	ll->save_ie = metadata_ll_save_ie;
	ll->init_index = metadata_ll_init_index;
	ll->open_index = metadata_ll_open;
	ll->max_entries = metadata_ll_max_entries;
	ll->commit = metadata_ll_commit;

	ll->nr_blocks = le64_to_cpu(smr.nr_blocks);
	ll->nr_allocated = le64_to_cpu(smr.nr_allocated);
	ll->bitmap_root = le64_to_cpu(smr.bitmap_root);
	ll->ref_count_root = le64_to_cpu(smr.ref_count_root);

	return ll->open_index(ll);
}

/*----------------------------------------------------------------*/

static inline int ie_cache_writeback(struct ll_disk *ll, struct ie_cache *iec)
{
	iec->dirty = false;
	__dm_bless_for_disk(iec->ie);
	return dm_btree_insert(&ll->bitmap_info, ll->bitmap_root,
			       &iec->index, &iec->ie, &ll->bitmap_root);
}

static inline unsigned int hash_index(dm_block_t index)
{
	return dm_hash_block(index, IE_CACHE_MASK);
}

static int disk_ll_load_ie(struct ll_disk *ll, dm_block_t index,
			   struct disk_index_entry *ie)
{
	int r;
	unsigned int h = hash_index(index);
	struct ie_cache *iec = ll->ie_cache + h;

	if (iec->valid) {
		if (iec->index == index) {
			memcpy(ie, &iec->ie, sizeof(*ie));
			return 0;
		}

		if (iec->dirty) {
			r = ie_cache_writeback(ll, iec);
			if (r)
				return r;
		}
	}

	r = dm_btree_lookup(&ll->bitmap_info, ll->bitmap_root, &index, ie);
	if (!r) {
		iec->valid = true;
		iec->dirty = false;
		iec->index = index;
		memcpy(&iec->ie, ie, sizeof(*ie));
	}

	return r;
}

static int disk_ll_save_ie(struct ll_disk *ll, dm_block_t index,
			   struct disk_index_entry *ie)
{
	int r;
	unsigned int h = hash_index(index);
	struct ie_cache *iec = ll->ie_cache + h;

	ll->bitmap_index_changed = true;
	if (iec->valid) {
		if (iec->index == index) {
			memcpy(&iec->ie, ie, sizeof(*ie));
			iec->dirty = true;
			return 0;
		}

		if (iec->dirty) {
			r = ie_cache_writeback(ll, iec);
			if (r)
				return r;
		}
	}

	iec->valid = true;
	iec->dirty = true;
	iec->index = index;
	memcpy(&iec->ie, ie, sizeof(*ie));
	return 0;
}

static int disk_ll_init_index(struct ll_disk *ll)
{
	unsigned int i;

	for (i = 0; i < IE_CACHE_SIZE; i++) {
		struct ie_cache *iec = ll->ie_cache + i;

		iec->valid = false;
		iec->dirty = false;
	}
	return dm_btree_empty(&ll->bitmap_info, &ll->bitmap_root);
}

static int disk_ll_open(struct ll_disk *ll)
{
	return 0;
}

static dm_block_t disk_ll_max_entries(struct ll_disk *ll)
{
	return -1ULL;
}

static int disk_ll_commit(struct ll_disk *ll)
{
	int r = 0;
	unsigned int i;

	for (i = 0; i < IE_CACHE_SIZE; i++) {
		struct ie_cache *iec = ll->ie_cache + i;

		if (iec->valid && iec->dirty)
			r = ie_cache_writeback(ll, iec);
	}

	return r;
}

int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
	int r;

	r = sm_ll_init(ll, tm);
	if (r < 0)
		return r;

	ll->load_ie = disk_ll_load_ie;
	ll->save_ie = disk_ll_save_ie;
	ll->init_index = disk_ll_init_index;
	ll->open_index = disk_ll_open;
	ll->max_entries = disk_ll_max_entries;
	ll->commit = disk_ll_commit;

	ll->nr_blocks = 0;
	ll->nr_allocated = 0;

	r = ll->init_index(ll);
	if (r < 0)
		return r;

	r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
	if (r < 0)
		return r;

	return 0;
}

int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
		    void *root_le, size_t len)
{
	int r;
	struct disk_sm_root *smr = root_le;

	if (len < sizeof(struct disk_sm_root)) {
		DMERR("sm_metadata root too small");
		return -ENOMEM;
	}

	r = sm_ll_init(ll, tm);
	if (r < 0)
		return r;

	ll->load_ie = disk_ll_load_ie;
	ll->save_ie = disk_ll_save_ie;
	ll->init_index = disk_ll_init_index;
	ll->open_index = disk_ll_open;
	ll->max_entries = disk_ll_max_entries;
	ll->commit = disk_ll_commit;

	ll->nr_blocks = le64_to_cpu(smr->nr_blocks);
	ll->nr_allocated = le64_to_cpu(smr->nr_allocated);
	ll->bitmap_root = le64_to_cpu(smr->bitmap_root);
	ll->ref_count_root = le64_to_cpu(smr->ref_count_root);

	return ll->open_index(ll);
}

/*----------------------------------------------------------------*/