forked from torvalds/linux
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathdm-cache-metadata.c
1299 lines (1039 loc) · 30.6 KB
/
dm-cache-metadata.c
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
/*
* Copyright (C) 2012 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#include "dm-cache-metadata.h"
#include "persistent-data/dm-array.h"
#include "persistent-data/dm-bitset.h"
#include "persistent-data/dm-space-map.h"
#include "persistent-data/dm-space-map-disk.h"
#include "persistent-data/dm-transaction-manager.h"
#include <linux/device-mapper.h>
/*----------------------------------------------------------------*/
#define DM_MSG_PREFIX "cache metadata"
#define CACHE_SUPERBLOCK_MAGIC 06142003
#define CACHE_SUPERBLOCK_LOCATION 0
/*
* defines a range of metadata versions that this module can handle.
*/
#define MIN_CACHE_VERSION 1
#define MAX_CACHE_VERSION 1
#define CACHE_METADATA_CACHE_SIZE 64
/*
* 3 for btree insert +
* 2 for btree lookup used within space map
*/
#define CACHE_MAX_CONCURRENT_LOCKS 5
#define SPACE_MAP_ROOT_SIZE 128
enum superblock_flag_bits {
/* for spotting crashes that would invalidate the dirty bitset */
CLEAN_SHUTDOWN,
};
/*
* Each mapping from cache block -> origin block carries a set of flags.
*/
enum mapping_bits {
/*
* A valid mapping. Because we're using an array we clear this
* flag for an non existant mapping.
*/
M_VALID = 1,
/*
* The data on the cache is different from that on the origin.
*/
M_DIRTY = 2
};
struct cache_disk_superblock {
__le32 csum;
__le32 flags;
__le64 blocknr;
__u8 uuid[16];
__le64 magic;
__le32 version;
__u8 policy_name[CACHE_POLICY_NAME_SIZE];
__le32 policy_hint_size;
__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
__le64 mapping_root;
__le64 hint_root;
__le64 discard_root;
__le64 discard_block_size;
__le64 discard_nr_blocks;
__le32 data_block_size;
__le32 metadata_block_size;
__le32 cache_blocks;
__le32 compat_flags;
__le32 compat_ro_flags;
__le32 incompat_flags;
__le32 read_hits;
__le32 read_misses;
__le32 write_hits;
__le32 write_misses;
__le32 policy_version[CACHE_POLICY_VERSION_SIZE];
} __packed;
struct dm_cache_metadata {
struct block_device *bdev;
struct dm_block_manager *bm;
struct dm_space_map *metadata_sm;
struct dm_transaction_manager *tm;
struct dm_array_info info;
struct dm_array_info hint_info;
struct dm_disk_bitset discard_info;
struct rw_semaphore root_lock;
dm_block_t root;
dm_block_t hint_root;
dm_block_t discard_root;
sector_t discard_block_size;
dm_oblock_t discard_nr_blocks;
sector_t data_block_size;
dm_cblock_t cache_blocks;
bool changed:1;
bool clean_when_opened:1;
char policy_name[CACHE_POLICY_NAME_SIZE];
unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
size_t policy_hint_size;
struct dm_cache_statistics stats;
/*
* Reading the space map root can fail, so we read it into this
* buffer before the superblock is locked and updated.
*/
__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
};
/*-------------------------------------------------------------------
* superblock validator
*-----------------------------------------------------------------*/
#define SUPERBLOCK_CSUM_XOR 9031977
static void sb_prepare_for_write(struct dm_block_validator *v,
struct dm_block *b,
size_t sb_block_size)
{
struct cache_disk_superblock *disk_super = dm_block_data(b);
disk_super->blocknr = cpu_to_le64(dm_block_location(b));
disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
sb_block_size - sizeof(__le32),
SUPERBLOCK_CSUM_XOR));
}
static int check_metadata_version(struct cache_disk_superblock *disk_super)
{
uint32_t metadata_version = le32_to_cpu(disk_super->version);
if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
return -EINVAL;
}
return 0;
}
static int sb_check(struct dm_block_validator *v,
struct dm_block *b,
size_t sb_block_size)
{
struct cache_disk_superblock *disk_super = dm_block_data(b);
__le32 csum_le;
if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
DMERR("sb_check failed: blocknr %llu: wanted %llu",
le64_to_cpu(disk_super->blocknr),
(unsigned long long)dm_block_location(b));
return -ENOTBLK;
}
if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
DMERR("sb_check failed: magic %llu: wanted %llu",
le64_to_cpu(disk_super->magic),
(unsigned long long)CACHE_SUPERBLOCK_MAGIC);
return -EILSEQ;
}
csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
sb_block_size - sizeof(__le32),
SUPERBLOCK_CSUM_XOR));
if (csum_le != disk_super->csum) {
DMERR("sb_check failed: csum %u: wanted %u",
le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
return -EILSEQ;
}
return check_metadata_version(disk_super);
}
static struct dm_block_validator sb_validator = {
.name = "superblock",
.prepare_for_write = sb_prepare_for_write,
.check = sb_check
};
/*----------------------------------------------------------------*/
static int superblock_read_lock(struct dm_cache_metadata *cmd,
struct dm_block **sblock)
{
return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
&sb_validator, sblock);
}
static int superblock_lock_zero(struct dm_cache_metadata *cmd,
struct dm_block **sblock)
{
return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
&sb_validator, sblock);
}
static int superblock_lock(struct dm_cache_metadata *cmd,
struct dm_block **sblock)
{
return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
&sb_validator, sblock);
}
/*----------------------------------------------------------------*/
static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
{
int r;
unsigned i;
struct dm_block *b;
__le64 *data_le, zero = cpu_to_le64(0);
unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
/*
* We can't use a validator here - it may be all zeroes.
*/
r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
if (r)
return r;
data_le = dm_block_data(b);
*result = true;
for (i = 0; i < sb_block_size; i++) {
if (data_le[i] != zero) {
*result = false;
break;
}
}
return dm_bm_unlock(b);
}
static void __setup_mapping_info(struct dm_cache_metadata *cmd)
{
struct dm_btree_value_type vt;
vt.context = NULL;
vt.size = sizeof(__le64);
vt.inc = NULL;
vt.dec = NULL;
vt.equal = NULL;
dm_array_info_init(&cmd->info, cmd->tm, &vt);
if (cmd->policy_hint_size) {
vt.size = sizeof(__le32);
dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
}
}
static int __save_sm_root(struct dm_cache_metadata *cmd)
{
int r;
size_t metadata_len;
r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
if (r < 0)
return r;
return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
metadata_len);
}
static void __copy_sm_root(struct dm_cache_metadata *cmd,
struct cache_disk_superblock *disk_super)
{
memcpy(&disk_super->metadata_space_map_root,
&cmd->metadata_space_map_root,
sizeof(cmd->metadata_space_map_root));
}
static int __write_initial_superblock(struct dm_cache_metadata *cmd)
{
int r;
struct dm_block *sblock;
struct cache_disk_superblock *disk_super;
sector_t bdev_size = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT;
/* FIXME: see if we can lose the max sectors limit */
if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
r = dm_tm_pre_commit(cmd->tm);
if (r < 0)
return r;
/*
* dm_sm_copy_root() can fail. So we need to do it before we start
* updating the superblock.
*/
r = __save_sm_root(cmd);
if (r)
return r;
r = superblock_lock_zero(cmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
disk_super->flags = 0;
memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
disk_super->version = cpu_to_le32(MAX_CACHE_VERSION);
memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
disk_super->policy_hint_size = 0;
__copy_sm_root(cmd, disk_super);
disk_super->mapping_root = cpu_to_le64(cmd->root);
disk_super->hint_root = cpu_to_le64(cmd->hint_root);
disk_super->discard_root = cpu_to_le64(cmd->discard_root);
disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
disk_super->discard_nr_blocks = cpu_to_le64(from_oblock(cmd->discard_nr_blocks));
disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE);
disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
disk_super->cache_blocks = cpu_to_le32(0);
disk_super->read_hits = cpu_to_le32(0);
disk_super->read_misses = cpu_to_le32(0);
disk_super->write_hits = cpu_to_le32(0);
disk_super->write_misses = cpu_to_le32(0);
return dm_tm_commit(cmd->tm, sblock);
}
static int __format_metadata(struct dm_cache_metadata *cmd)
{
int r;
r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
&cmd->tm, &cmd->metadata_sm);
if (r < 0) {
DMERR("tm_create_with_sm failed");
return r;
}
__setup_mapping_info(cmd);
r = dm_array_empty(&cmd->info, &cmd->root);
if (r < 0)
goto bad;
dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
if (r < 0)
goto bad;
cmd->discard_block_size = 0;
cmd->discard_nr_blocks = 0;
r = __write_initial_superblock(cmd);
if (r)
goto bad;
cmd->clean_when_opened = true;
return 0;
bad:
dm_tm_destroy(cmd->tm);
dm_sm_destroy(cmd->metadata_sm);
return r;
}
static int __check_incompat_features(struct cache_disk_superblock *disk_super,
struct dm_cache_metadata *cmd)
{
uint32_t features;
features = le32_to_cpu(disk_super->incompat_flags) & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
if (features) {
DMERR("could not access metadata due to unsupported optional features (%lx).",
(unsigned long)features);
return -EINVAL;
}
/*
* Check for read-only metadata to skip the following RDWR checks.
*/
if (get_disk_ro(cmd->bdev->bd_disk))
return 0;
features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
if (features) {
DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
(unsigned long)features);
return -EINVAL;
}
return 0;
}
static int __open_metadata(struct dm_cache_metadata *cmd)
{
int r;
struct dm_block *sblock;
struct cache_disk_superblock *disk_super;
unsigned long sb_flags;
r = superblock_read_lock(cmd, &sblock);
if (r < 0) {
DMERR("couldn't read lock superblock");
return r;
}
disk_super = dm_block_data(sblock);
/* Verify the data block size hasn't changed */
if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) {
DMERR("changing the data block size (from %u to %llu) is not supported",
le32_to_cpu(disk_super->data_block_size),
(unsigned long long)cmd->data_block_size);
r = -EINVAL;
goto bad;
}
r = __check_incompat_features(disk_super, cmd);
if (r < 0)
goto bad;
r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
disk_super->metadata_space_map_root,
sizeof(disk_super->metadata_space_map_root),
&cmd->tm, &cmd->metadata_sm);
if (r < 0) {
DMERR("tm_open_with_sm failed");
goto bad;
}
__setup_mapping_info(cmd);
dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
sb_flags = le32_to_cpu(disk_super->flags);
cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
return dm_bm_unlock(sblock);
bad:
dm_bm_unlock(sblock);
return r;
}
static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
bool format_device)
{
int r;
bool unformatted = false;
r = __superblock_all_zeroes(cmd->bm, &unformatted);
if (r)
return r;
if (unformatted)
return format_device ? __format_metadata(cmd) : -EPERM;
return __open_metadata(cmd);
}
static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
bool may_format_device)
{
int r;
cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
CACHE_METADATA_CACHE_SIZE,
CACHE_MAX_CONCURRENT_LOCKS);
if (IS_ERR(cmd->bm)) {
DMERR("could not create block manager");
return PTR_ERR(cmd->bm);
}
r = __open_or_format_metadata(cmd, may_format_device);
if (r)
dm_block_manager_destroy(cmd->bm);
return r;
}
static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
{
dm_sm_destroy(cmd->metadata_sm);
dm_tm_destroy(cmd->tm);
dm_block_manager_destroy(cmd->bm);
}
typedef unsigned long (*flags_mutator)(unsigned long);
static void update_flags(struct cache_disk_superblock *disk_super,
flags_mutator mutator)
{
uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
disk_super->flags = cpu_to_le32(sb_flags);
}
static unsigned long set_clean_shutdown(unsigned long flags)
{
set_bit(CLEAN_SHUTDOWN, &flags);
return flags;
}
static unsigned long clear_clean_shutdown(unsigned long flags)
{
clear_bit(CLEAN_SHUTDOWN, &flags);
return flags;
}
static void read_superblock_fields(struct dm_cache_metadata *cmd,
struct cache_disk_superblock *disk_super)
{
cmd->root = le64_to_cpu(disk_super->mapping_root);
cmd->hint_root = le64_to_cpu(disk_super->hint_root);
cmd->discard_root = le64_to_cpu(disk_super->discard_root);
cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
cmd->discard_nr_blocks = to_oblock(le64_to_cpu(disk_super->discard_nr_blocks));
cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
cmd->changed = false;
}
/*
* The mutator updates the superblock flags.
*/
static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
flags_mutator mutator)
{
int r;
struct cache_disk_superblock *disk_super;
struct dm_block *sblock;
r = superblock_lock(cmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
update_flags(disk_super, mutator);
read_superblock_fields(cmd, disk_super);
dm_bm_unlock(sblock);
return dm_bm_flush(cmd->bm);
}
static int __begin_transaction(struct dm_cache_metadata *cmd)
{
int r;
struct cache_disk_superblock *disk_super;
struct dm_block *sblock;
/*
* We re-read the superblock every time. Shouldn't need to do this
* really.
*/
r = superblock_read_lock(cmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
read_superblock_fields(cmd, disk_super);
dm_bm_unlock(sblock);
return 0;
}
static int __commit_transaction(struct dm_cache_metadata *cmd,
flags_mutator mutator)
{
int r;
struct cache_disk_superblock *disk_super;
struct dm_block *sblock;
/*
* We need to know if the cache_disk_superblock exceeds a 512-byte sector.
*/
BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
&cmd->discard_root);
if (r)
return r;
r = dm_tm_pre_commit(cmd->tm);
if (r < 0)
return r;
r = __save_sm_root(cmd);
if (r)
return r;
r = superblock_lock(cmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
if (mutator)
update_flags(disk_super, mutator);
disk_super->mapping_root = cpu_to_le64(cmd->root);
disk_super->hint_root = cpu_to_le64(cmd->hint_root);
disk_super->discard_root = cpu_to_le64(cmd->discard_root);
disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
disk_super->discard_nr_blocks = cpu_to_le64(from_oblock(cmd->discard_nr_blocks));
disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
__copy_sm_root(cmd, disk_super);
return dm_tm_commit(cmd->tm, sblock);
}
/*----------------------------------------------------------------*/
/*
* The mappings are held in a dm-array that has 64-bit values stored in
* little-endian format. The index is the cblock, the high 48bits of the
* value are the oblock and the low 16 bit the flags.
*/
#define FLAGS_MASK ((1 << 16) - 1)
static __le64 pack_value(dm_oblock_t block, unsigned flags)
{
uint64_t value = from_oblock(block);
value <<= 16;
value = value | (flags & FLAGS_MASK);
return cpu_to_le64(value);
}
static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
{
uint64_t value = le64_to_cpu(value_le);
uint64_t b = value >> 16;
*block = to_oblock(b);
*flags = value & FLAGS_MASK;
}
/*----------------------------------------------------------------*/
struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
sector_t data_block_size,
bool may_format_device,
size_t policy_hint_size)
{
int r;
struct dm_cache_metadata *cmd;
cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
if (!cmd) {
DMERR("could not allocate metadata struct");
return NULL;
}
init_rwsem(&cmd->root_lock);
cmd->bdev = bdev;
cmd->data_block_size = data_block_size;
cmd->cache_blocks = 0;
cmd->policy_hint_size = policy_hint_size;
cmd->changed = true;
r = __create_persistent_data_objects(cmd, may_format_device);
if (r) {
kfree(cmd);
return ERR_PTR(r);
}
r = __begin_transaction_flags(cmd, clear_clean_shutdown);
if (r < 0) {
dm_cache_metadata_close(cmd);
return ERR_PTR(r);
}
return cmd;
}
void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
{
__destroy_persistent_data_objects(cmd);
kfree(cmd);
}
/*
* Checks that the given cache block is either unmapped or clean.
*/
static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
bool *result)
{
int r;
__le64 value;
dm_oblock_t ob;
unsigned flags;
r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
if (r) {
DMERR("block_unmapped_or_clean failed");
return r;
}
unpack_value(value, &ob, &flags);
*result = !((flags & M_VALID) && (flags & M_DIRTY));
return 0;
}
static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
dm_cblock_t begin, dm_cblock_t end,
bool *result)
{
int r;
*result = true;
while (begin != end) {
r = block_unmapped_or_clean(cmd, begin, result);
if (r)
return r;
if (!*result) {
DMERR("cache block %llu is dirty",
(unsigned long long) from_cblock(begin));
return 0;
}
begin = to_cblock(from_cblock(begin) + 1);
}
return 0;
}
int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
{
int r;
bool clean;
__le64 null_mapping = pack_value(0, 0);
down_write(&cmd->root_lock);
__dm_bless_for_disk(&null_mapping);
if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
if (r) {
__dm_unbless_for_disk(&null_mapping);
goto out;
}
if (!clean) {
DMERR("unable to shrink cache due to dirty blocks");
r = -EINVAL;
__dm_unbless_for_disk(&null_mapping);
goto out;
}
}
r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
from_cblock(new_cache_size),
&null_mapping, &cmd->root);
if (!r)
cmd->cache_blocks = new_cache_size;
cmd->changed = true;
out:
up_write(&cmd->root_lock);
return r;
}
int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
sector_t discard_block_size,
dm_oblock_t new_nr_entries)
{
int r;
down_write(&cmd->root_lock);
r = dm_bitset_resize(&cmd->discard_info,
cmd->discard_root,
from_oblock(cmd->discard_nr_blocks),
from_oblock(new_nr_entries),
false, &cmd->discard_root);
if (!r) {
cmd->discard_block_size = discard_block_size;
cmd->discard_nr_blocks = new_nr_entries;
}
cmd->changed = true;
up_write(&cmd->root_lock);
return r;
}
static int __set_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
{
return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
from_oblock(b), &cmd->discard_root);
}
static int __clear_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
{
return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
from_oblock(b), &cmd->discard_root);
}
static int __is_discarded(struct dm_cache_metadata *cmd, dm_oblock_t b,
bool *is_discarded)
{
return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
from_oblock(b), &cmd->discard_root,
is_discarded);
}
static int __discard(struct dm_cache_metadata *cmd,
dm_oblock_t dblock, bool discard)
{
int r;
r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
if (r)
return r;
cmd->changed = true;
return 0;
}
int dm_cache_set_discard(struct dm_cache_metadata *cmd,
dm_oblock_t dblock, bool discard)
{
int r;
down_write(&cmd->root_lock);
r = __discard(cmd, dblock, discard);
up_write(&cmd->root_lock);
return r;
}
static int __load_discards(struct dm_cache_metadata *cmd,
load_discard_fn fn, void *context)
{
int r = 0;
dm_block_t b;
bool discard;
for (b = 0; b < from_oblock(cmd->discard_nr_blocks); b++) {
dm_oblock_t dblock = to_oblock(b);
if (cmd->clean_when_opened) {
r = __is_discarded(cmd, dblock, &discard);
if (r)
return r;
} else
discard = false;
r = fn(context, cmd->discard_block_size, dblock, discard);
if (r)
break;
}
return r;
}
int dm_cache_load_discards(struct dm_cache_metadata *cmd,
load_discard_fn fn, void *context)
{
int r;
down_read(&cmd->root_lock);
r = __load_discards(cmd, fn, context);
up_read(&cmd->root_lock);
return r;
}
dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd)
{
dm_cblock_t r;
down_read(&cmd->root_lock);
r = cmd->cache_blocks;
up_read(&cmd->root_lock);
return r;
}
static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
{
int r;
__le64 value = pack_value(0, 0);
__dm_bless_for_disk(&value);
r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
&value, &cmd->root);
if (r)
return r;
cmd->changed = true;
return 0;
}
int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
{
int r;
down_write(&cmd->root_lock);
r = __remove(cmd, cblock);
up_write(&cmd->root_lock);
return r;
}
static int __insert(struct dm_cache_metadata *cmd,
dm_cblock_t cblock, dm_oblock_t oblock)
{
int r;
__le64 value = pack_value(oblock, M_VALID);
__dm_bless_for_disk(&value);
r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
&value, &cmd->root);
if (r)
return r;
cmd->changed = true;
return 0;
}
int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
dm_cblock_t cblock, dm_oblock_t oblock)
{
int r;
down_write(&cmd->root_lock);
r = __insert(cmd, cblock, oblock);
up_write(&cmd->root_lock);
return r;
}
struct thunk {
load_mapping_fn fn;
void *context;
struct dm_cache_metadata *cmd;
bool respect_dirty_flags;
bool hints_valid;
};
static bool policy_unchanged(struct dm_cache_metadata *cmd,
struct dm_cache_policy *policy)
{
const char *policy_name = dm_cache_policy_get_name(policy);
const unsigned *policy_version = dm_cache_policy_get_version(policy);
size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
/*
* Ensure policy names match.
*/
if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
return false;
/*
* Ensure policy major versions match.
*/
if (cmd->policy_version[0] != policy_version[0])
return false;
/*
* Ensure policy hint sizes match.
*/
if (cmd->policy_hint_size != policy_hint_size)
return false;