video: tegra: nvmap: add handle share count to debug stats
[linux-3.10.git] / drivers / md / dm-cache-metadata.c
1 /*
2  * Copyright (C) 2012 Red Hat, Inc.
3  *
4  * This file is released under the GPL.
5  */
6
7 #include "dm-cache-metadata.h"
8
9 #include "persistent-data/dm-array.h"
10 #include "persistent-data/dm-bitset.h"
11 #include "persistent-data/dm-space-map.h"
12 #include "persistent-data/dm-space-map-disk.h"
13 #include "persistent-data/dm-transaction-manager.h"
14
15 #include <linux/device-mapper.h>
16
17 /*----------------------------------------------------------------*/
18
19 #define DM_MSG_PREFIX   "cache metadata"
20
21 #define CACHE_SUPERBLOCK_MAGIC 06142003
22 #define CACHE_SUPERBLOCK_LOCATION 0
23 #define CACHE_VERSION 1
24 #define CACHE_METADATA_CACHE_SIZE 64
25
26 /*
27  *  3 for btree insert +
28  *  2 for btree lookup used within space map
29  */
30 #define CACHE_MAX_CONCURRENT_LOCKS 5
31 #define SPACE_MAP_ROOT_SIZE 128
32
33 enum superblock_flag_bits {
34         /* for spotting crashes that would invalidate the dirty bitset */
35         CLEAN_SHUTDOWN,
36 };
37
38 /*
39  * Each mapping from cache block -> origin block carries a set of flags.
40  */
41 enum mapping_bits {
42         /*
43          * A valid mapping.  Because we're using an array we clear this
44          * flag for an non existant mapping.
45          */
46         M_VALID = 1,
47
48         /*
49          * The data on the cache is different from that on the origin.
50          */
51         M_DIRTY = 2
52 };
53
54 struct cache_disk_superblock {
55         __le32 csum;
56         __le32 flags;
57         __le64 blocknr;
58
59         __u8 uuid[16];
60         __le64 magic;
61         __le32 version;
62
63         __u8 policy_name[CACHE_POLICY_NAME_SIZE];
64         __le32 policy_hint_size;
65
66         __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
67         __le64 mapping_root;
68         __le64 hint_root;
69
70         __le64 discard_root;
71         __le64 discard_block_size;
72         __le64 discard_nr_blocks;
73
74         __le32 data_block_size;
75         __le32 metadata_block_size;
76         __le32 cache_blocks;
77
78         __le32 compat_flags;
79         __le32 compat_ro_flags;
80         __le32 incompat_flags;
81
82         __le32 read_hits;
83         __le32 read_misses;
84         __le32 write_hits;
85         __le32 write_misses;
86
87         __le32 policy_version[CACHE_POLICY_VERSION_SIZE];
88 } __packed;
89
90 struct dm_cache_metadata {
91         struct block_device *bdev;
92         struct dm_block_manager *bm;
93         struct dm_space_map *metadata_sm;
94         struct dm_transaction_manager *tm;
95
96         struct dm_array_info info;
97         struct dm_array_info hint_info;
98         struct dm_disk_bitset discard_info;
99
100         struct rw_semaphore root_lock;
101         dm_block_t root;
102         dm_block_t hint_root;
103         dm_block_t discard_root;
104
105         sector_t discard_block_size;
106         dm_dblock_t discard_nr_blocks;
107
108         sector_t data_block_size;
109         dm_cblock_t cache_blocks;
110         bool changed:1;
111         bool clean_when_opened:1;
112
113         char policy_name[CACHE_POLICY_NAME_SIZE];
114         unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
115         size_t policy_hint_size;
116         struct dm_cache_statistics stats;
117 };
118
119 /*-------------------------------------------------------------------
120  * superblock validator
121  *-----------------------------------------------------------------*/
122
123 #define SUPERBLOCK_CSUM_XOR 9031977
124
125 static void sb_prepare_for_write(struct dm_block_validator *v,
126                                  struct dm_block *b,
127                                  size_t sb_block_size)
128 {
129         struct cache_disk_superblock *disk_super = dm_block_data(b);
130
131         disk_super->blocknr = cpu_to_le64(dm_block_location(b));
132         disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
133                                                       sb_block_size - sizeof(__le32),
134                                                       SUPERBLOCK_CSUM_XOR));
135 }
136
137 static int sb_check(struct dm_block_validator *v,
138                     struct dm_block *b,
139                     size_t sb_block_size)
140 {
141         struct cache_disk_superblock *disk_super = dm_block_data(b);
142         __le32 csum_le;
143
144         if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
145                 DMERR("sb_check failed: blocknr %llu: wanted %llu",
146                       le64_to_cpu(disk_super->blocknr),
147                       (unsigned long long)dm_block_location(b));
148                 return -ENOTBLK;
149         }
150
151         if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) {
152                 DMERR("sb_check failed: magic %llu: wanted %llu",
153                       le64_to_cpu(disk_super->magic),
154                       (unsigned long long)CACHE_SUPERBLOCK_MAGIC);
155                 return -EILSEQ;
156         }
157
158         csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
159                                              sb_block_size - sizeof(__le32),
160                                              SUPERBLOCK_CSUM_XOR));
161         if (csum_le != disk_super->csum) {
162                 DMERR("sb_check failed: csum %u: wanted %u",
163                       le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
164                 return -EILSEQ;
165         }
166
167         return 0;
168 }
169
170 static struct dm_block_validator sb_validator = {
171         .name = "superblock",
172         .prepare_for_write = sb_prepare_for_write,
173         .check = sb_check
174 };
175
176 /*----------------------------------------------------------------*/
177
178 static int superblock_read_lock(struct dm_cache_metadata *cmd,
179                                 struct dm_block **sblock)
180 {
181         return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
182                                &sb_validator, sblock);
183 }
184
185 static int superblock_lock_zero(struct dm_cache_metadata *cmd,
186                                 struct dm_block **sblock)
187 {
188         return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
189                                      &sb_validator, sblock);
190 }
191
192 static int superblock_lock(struct dm_cache_metadata *cmd,
193                            struct dm_block **sblock)
194 {
195         return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
196                                 &sb_validator, sblock);
197 }
198
199 /*----------------------------------------------------------------*/
200
201 static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
202 {
203         int r;
204         unsigned i;
205         struct dm_block *b;
206         __le64 *data_le, zero = cpu_to_le64(0);
207         unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
208
209         /*
210          * We can't use a validator here - it may be all zeroes.
211          */
212         r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
213         if (r)
214                 return r;
215
216         data_le = dm_block_data(b);
217         *result = 1;
218         for (i = 0; i < sb_block_size; i++) {
219                 if (data_le[i] != zero) {
220                         *result = 0;
221                         break;
222                 }
223         }
224
225         return dm_bm_unlock(b);
226 }
227
228 static void __setup_mapping_info(struct dm_cache_metadata *cmd)
229 {
230         struct dm_btree_value_type vt;
231
232         vt.context = NULL;
233         vt.size = sizeof(__le64);
234         vt.inc = NULL;
235         vt.dec = NULL;
236         vt.equal = NULL;
237         dm_array_info_init(&cmd->info, cmd->tm, &vt);
238
239         if (cmd->policy_hint_size) {
240                 vt.size = sizeof(__le32);
241                 dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
242         }
243 }
244
245 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
246 {
247         int r;
248         struct dm_block *sblock;
249         size_t metadata_len;
250         struct cache_disk_superblock *disk_super;
251         sector_t bdev_size = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT;
252
253         /* FIXME: see if we can lose the max sectors limit */
254         if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
255                 bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
256
257         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
258         if (r < 0)
259                 return r;
260
261         r = dm_tm_pre_commit(cmd->tm);
262         if (r < 0)
263                 return r;
264
265         r = superblock_lock_zero(cmd, &sblock);
266         if (r)
267                 return r;
268
269         disk_super = dm_block_data(sblock);
270         disk_super->flags = 0;
271         memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
272         disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
273         disk_super->version = cpu_to_le32(CACHE_VERSION);
274         memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
275         memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
276         disk_super->policy_hint_size = 0;
277
278         r = dm_sm_copy_root(cmd->metadata_sm, &disk_super->metadata_space_map_root,
279                             metadata_len);
280         if (r < 0)
281                 goto bad_locked;
282
283         disk_super->mapping_root = cpu_to_le64(cmd->root);
284         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
285         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
286         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
287         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
288         disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
289         disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
290         disk_super->cache_blocks = cpu_to_le32(0);
291
292         disk_super->read_hits = cpu_to_le32(0);
293         disk_super->read_misses = cpu_to_le32(0);
294         disk_super->write_hits = cpu_to_le32(0);
295         disk_super->write_misses = cpu_to_le32(0);
296
297         return dm_tm_commit(cmd->tm, sblock);
298
299 bad_locked:
300         dm_bm_unlock(sblock);
301         return r;
302 }
303
304 static int __format_metadata(struct dm_cache_metadata *cmd)
305 {
306         int r;
307
308         r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
309                                  &cmd->tm, &cmd->metadata_sm);
310         if (r < 0) {
311                 DMERR("tm_create_with_sm failed");
312                 return r;
313         }
314
315         __setup_mapping_info(cmd);
316
317         r = dm_array_empty(&cmd->info, &cmd->root);
318         if (r < 0)
319                 goto bad;
320
321         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
322
323         r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
324         if (r < 0)
325                 goto bad;
326
327         cmd->discard_block_size = 0;
328         cmd->discard_nr_blocks = 0;
329
330         r = __write_initial_superblock(cmd);
331         if (r)
332                 goto bad;
333
334         cmd->clean_when_opened = true;
335         return 0;
336
337 bad:
338         dm_tm_destroy(cmd->tm);
339         dm_sm_destroy(cmd->metadata_sm);
340
341         return r;
342 }
343
344 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
345                                      struct dm_cache_metadata *cmd)
346 {
347         uint32_t features;
348
349         features = le32_to_cpu(disk_super->incompat_flags) & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
350         if (features) {
351                 DMERR("could not access metadata due to unsupported optional features (%lx).",
352                       (unsigned long)features);
353                 return -EINVAL;
354         }
355
356         /*
357          * Check for read-only metadata to skip the following RDWR checks.
358          */
359         if (get_disk_ro(cmd->bdev->bd_disk))
360                 return 0;
361
362         features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP;
363         if (features) {
364                 DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
365                       (unsigned long)features);
366                 return -EINVAL;
367         }
368
369         return 0;
370 }
371
372 static int __open_metadata(struct dm_cache_metadata *cmd)
373 {
374         int r;
375         struct dm_block *sblock;
376         struct cache_disk_superblock *disk_super;
377         unsigned long sb_flags;
378
379         r = superblock_read_lock(cmd, &sblock);
380         if (r < 0) {
381                 DMERR("couldn't read lock superblock");
382                 return r;
383         }
384
385         disk_super = dm_block_data(sblock);
386
387         r = __check_incompat_features(disk_super, cmd);
388         if (r < 0)
389                 goto bad;
390
391         r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
392                                disk_super->metadata_space_map_root,
393                                sizeof(disk_super->metadata_space_map_root),
394                                &cmd->tm, &cmd->metadata_sm);
395         if (r < 0) {
396                 DMERR("tm_open_with_sm failed");
397                 goto bad;
398         }
399
400         __setup_mapping_info(cmd);
401         dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
402         sb_flags = le32_to_cpu(disk_super->flags);
403         cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
404         return dm_bm_unlock(sblock);
405
406 bad:
407         dm_bm_unlock(sblock);
408         return r;
409 }
410
411 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
412                                      bool format_device)
413 {
414         int r, unformatted;
415
416         r = __superblock_all_zeroes(cmd->bm, &unformatted);
417         if (r)
418                 return r;
419
420         if (unformatted)
421                 return format_device ? __format_metadata(cmd) : -EPERM;
422
423         return __open_metadata(cmd);
424 }
425
426 static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
427                                             bool may_format_device)
428 {
429         int r;
430         cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE,
431                                           CACHE_METADATA_CACHE_SIZE,
432                                           CACHE_MAX_CONCURRENT_LOCKS);
433         if (IS_ERR(cmd->bm)) {
434                 DMERR("could not create block manager");
435                 return PTR_ERR(cmd->bm);
436         }
437
438         r = __open_or_format_metadata(cmd, may_format_device);
439         if (r)
440                 dm_block_manager_destroy(cmd->bm);
441
442         return r;
443 }
444
445 static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
446 {
447         dm_sm_destroy(cmd->metadata_sm);
448         dm_tm_destroy(cmd->tm);
449         dm_block_manager_destroy(cmd->bm);
450 }
451
452 typedef unsigned long (*flags_mutator)(unsigned long);
453
454 static void update_flags(struct cache_disk_superblock *disk_super,
455                          flags_mutator mutator)
456 {
457         uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
458         disk_super->flags = cpu_to_le32(sb_flags);
459 }
460
461 static unsigned long set_clean_shutdown(unsigned long flags)
462 {
463         set_bit(CLEAN_SHUTDOWN, &flags);
464         return flags;
465 }
466
467 static unsigned long clear_clean_shutdown(unsigned long flags)
468 {
469         clear_bit(CLEAN_SHUTDOWN, &flags);
470         return flags;
471 }
472
473 static void read_superblock_fields(struct dm_cache_metadata *cmd,
474                                    struct cache_disk_superblock *disk_super)
475 {
476         cmd->root = le64_to_cpu(disk_super->mapping_root);
477         cmd->hint_root = le64_to_cpu(disk_super->hint_root);
478         cmd->discard_root = le64_to_cpu(disk_super->discard_root);
479         cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
480         cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
481         cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
482         cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
483         strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
484         cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
485         cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
486         cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
487         cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
488
489         cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
490         cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
491         cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
492         cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
493
494         cmd->changed = false;
495 }
496
497 /*
498  * The mutator updates the superblock flags.
499  */
500 static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
501                                      flags_mutator mutator)
502 {
503         int r;
504         struct cache_disk_superblock *disk_super;
505         struct dm_block *sblock;
506
507         r = superblock_lock(cmd, &sblock);
508         if (r)
509                 return r;
510
511         disk_super = dm_block_data(sblock);
512         update_flags(disk_super, mutator);
513         read_superblock_fields(cmd, disk_super);
514         dm_bm_unlock(sblock);
515
516         return dm_bm_flush(cmd->bm);
517 }
518
519 static int __begin_transaction(struct dm_cache_metadata *cmd)
520 {
521         int r;
522         struct cache_disk_superblock *disk_super;
523         struct dm_block *sblock;
524
525         /*
526          * We re-read the superblock every time.  Shouldn't need to do this
527          * really.
528          */
529         r = superblock_read_lock(cmd, &sblock);
530         if (r)
531                 return r;
532
533         disk_super = dm_block_data(sblock);
534         read_superblock_fields(cmd, disk_super);
535         dm_bm_unlock(sblock);
536
537         return 0;
538 }
539
540 static int __commit_transaction(struct dm_cache_metadata *cmd,
541                                 flags_mutator mutator)
542 {
543         int r;
544         size_t metadata_len;
545         struct cache_disk_superblock *disk_super;
546         struct dm_block *sblock;
547
548         /*
549          * We need to know if the cache_disk_superblock exceeds a 512-byte sector.
550          */
551         BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
552
553         r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
554                             &cmd->discard_root);
555         if (r)
556                 return r;
557
558         r = dm_tm_pre_commit(cmd->tm);
559         if (r < 0)
560                 return r;
561
562         r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
563         if (r < 0)
564                 return r;
565
566         r = superblock_lock(cmd, &sblock);
567         if (r)
568                 return r;
569
570         disk_super = dm_block_data(sblock);
571
572         if (mutator)
573                 update_flags(disk_super, mutator);
574
575         disk_super->mapping_root = cpu_to_le64(cmd->root);
576         disk_super->hint_root = cpu_to_le64(cmd->hint_root);
577         disk_super->discard_root = cpu_to_le64(cmd->discard_root);
578         disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
579         disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
580         disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
581         strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
582         disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
583         disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
584         disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
585
586         disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
587         disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
588         disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
589         disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
590
591         r = dm_sm_copy_root(cmd->metadata_sm, &disk_super->metadata_space_map_root,
592                             metadata_len);
593         if (r < 0) {
594                 dm_bm_unlock(sblock);
595                 return r;
596         }
597
598         return dm_tm_commit(cmd->tm, sblock);
599 }
600
601 /*----------------------------------------------------------------*/
602
603 /*
604  * The mappings are held in a dm-array that has 64-bit values stored in
605  * little-endian format.  The index is the cblock, the high 48bits of the
606  * value are the oblock and the low 16 bit the flags.
607  */
608 #define FLAGS_MASK ((1 << 16) - 1)
609
610 static __le64 pack_value(dm_oblock_t block, unsigned flags)
611 {
612         uint64_t value = from_oblock(block);
613         value <<= 16;
614         value = value | (flags & FLAGS_MASK);
615         return cpu_to_le64(value);
616 }
617
618 static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
619 {
620         uint64_t value = le64_to_cpu(value_le);
621         uint64_t b = value >> 16;
622         *block = to_oblock(b);
623         *flags = value & FLAGS_MASK;
624 }
625
626 /*----------------------------------------------------------------*/
627
628 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
629                                                  sector_t data_block_size,
630                                                  bool may_format_device,
631                                                  size_t policy_hint_size)
632 {
633         int r;
634         struct dm_cache_metadata *cmd;
635
636         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
637         if (!cmd) {
638                 DMERR("could not allocate metadata struct");
639                 return NULL;
640         }
641
642         init_rwsem(&cmd->root_lock);
643         cmd->bdev = bdev;
644         cmd->data_block_size = data_block_size;
645         cmd->cache_blocks = 0;
646         cmd->policy_hint_size = policy_hint_size;
647         cmd->changed = true;
648
649         r = __create_persistent_data_objects(cmd, may_format_device);
650         if (r) {
651                 kfree(cmd);
652                 return ERR_PTR(r);
653         }
654
655         r = __begin_transaction_flags(cmd, clear_clean_shutdown);
656         if (r < 0) {
657                 dm_cache_metadata_close(cmd);
658                 return ERR_PTR(r);
659         }
660
661         return cmd;
662 }
663
664 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
665 {
666         __destroy_persistent_data_objects(cmd);
667         kfree(cmd);
668 }
669
670 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
671 {
672         int r;
673         __le64 null_mapping = pack_value(0, 0);
674
675         down_write(&cmd->root_lock);
676         __dm_bless_for_disk(&null_mapping);
677         r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
678                             from_cblock(new_cache_size),
679                             &null_mapping, &cmd->root);
680         if (!r)
681                 cmd->cache_blocks = new_cache_size;
682         cmd->changed = true;
683         up_write(&cmd->root_lock);
684
685         return r;
686 }
687
688 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
689                                    sector_t discard_block_size,
690                                    dm_dblock_t new_nr_entries)
691 {
692         int r;
693
694         down_write(&cmd->root_lock);
695         r = dm_bitset_resize(&cmd->discard_info,
696                              cmd->discard_root,
697                              from_dblock(cmd->discard_nr_blocks),
698                              from_dblock(new_nr_entries),
699                              false, &cmd->discard_root);
700         if (!r) {
701                 cmd->discard_block_size = discard_block_size;
702                 cmd->discard_nr_blocks = new_nr_entries;
703         }
704
705         cmd->changed = true;
706         up_write(&cmd->root_lock);
707
708         return r;
709 }
710
711 static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
712 {
713         return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
714                                  from_dblock(b), &cmd->discard_root);
715 }
716
717 static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
718 {
719         return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
720                                    from_dblock(b), &cmd->discard_root);
721 }
722
723 static int __is_discarded(struct dm_cache_metadata *cmd, dm_dblock_t b,
724                           bool *is_discarded)
725 {
726         return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
727                                   from_dblock(b), &cmd->discard_root,
728                                   is_discarded);
729 }
730
731 static int __discard(struct dm_cache_metadata *cmd,
732                      dm_dblock_t dblock, bool discard)
733 {
734         int r;
735
736         r = (discard ? __set_discard : __clear_discard)(cmd, dblock);
737         if (r)
738                 return r;
739
740         cmd->changed = true;
741         return 0;
742 }
743
744 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
745                          dm_dblock_t dblock, bool discard)
746 {
747         int r;
748
749         down_write(&cmd->root_lock);
750         r = __discard(cmd, dblock, discard);
751         up_write(&cmd->root_lock);
752
753         return r;
754 }
755
756 static int __load_discards(struct dm_cache_metadata *cmd,
757                            load_discard_fn fn, void *context)
758 {
759         int r = 0;
760         dm_block_t b;
761         bool discard;
762
763         for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
764                 dm_dblock_t dblock = to_dblock(b);
765
766                 if (cmd->clean_when_opened) {
767                         r = __is_discarded(cmd, dblock, &discard);
768                         if (r)
769                                 return r;
770                 } else
771                         discard = false;
772
773                 r = fn(context, cmd->discard_block_size, dblock, discard);
774                 if (r)
775                         break;
776         }
777
778         return r;
779 }
780
781 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
782                            load_discard_fn fn, void *context)
783 {
784         int r;
785
786         down_read(&cmd->root_lock);
787         r = __load_discards(cmd, fn, context);
788         up_read(&cmd->root_lock);
789
790         return r;
791 }
792
793 dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd)
794 {
795         dm_cblock_t r;
796
797         down_read(&cmd->root_lock);
798         r = cmd->cache_blocks;
799         up_read(&cmd->root_lock);
800
801         return r;
802 }
803
804 static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
805 {
806         int r;
807         __le64 value = pack_value(0, 0);
808
809         __dm_bless_for_disk(&value);
810         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
811                                &value, &cmd->root);
812         if (r)
813                 return r;
814
815         cmd->changed = true;
816         return 0;
817 }
818
819 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock)
820 {
821         int r;
822
823         down_write(&cmd->root_lock);
824         r = __remove(cmd, cblock);
825         up_write(&cmd->root_lock);
826
827         return r;
828 }
829
830 static int __insert(struct dm_cache_metadata *cmd,
831                     dm_cblock_t cblock, dm_oblock_t oblock)
832 {
833         int r;
834         __le64 value = pack_value(oblock, M_VALID);
835         __dm_bless_for_disk(&value);
836
837         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
838                                &value, &cmd->root);
839         if (r)
840                 return r;
841
842         cmd->changed = true;
843         return 0;
844 }
845
846 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd,
847                             dm_cblock_t cblock, dm_oblock_t oblock)
848 {
849         int r;
850
851         down_write(&cmd->root_lock);
852         r = __insert(cmd, cblock, oblock);
853         up_write(&cmd->root_lock);
854
855         return r;
856 }
857
858 struct thunk {
859         load_mapping_fn fn;
860         void *context;
861
862         struct dm_cache_metadata *cmd;
863         bool respect_dirty_flags;
864         bool hints_valid;
865 };
866
867 static bool policy_unchanged(struct dm_cache_metadata *cmd,
868                              struct dm_cache_policy *policy)
869 {
870         const char *policy_name = dm_cache_policy_get_name(policy);
871         const unsigned *policy_version = dm_cache_policy_get_version(policy);
872         size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
873
874         /*
875          * Ensure policy names match.
876          */
877         if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
878                 return false;
879
880         /*
881          * Ensure policy major versions match.
882          */
883         if (cmd->policy_version[0] != policy_version[0])
884                 return false;
885
886         /*
887          * Ensure policy hint sizes match.
888          */
889         if (cmd->policy_hint_size != policy_hint_size)
890                 return false;
891
892         return true;
893 }
894
895 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
896 {
897         return cmd->hint_root && cmd->policy_hint_size;
898 }
899
900 static bool hints_array_available(struct dm_cache_metadata *cmd,
901                                   struct dm_cache_policy *policy)
902 {
903         return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
904                 hints_array_initialized(cmd);
905 }
906
907 static int __load_mapping(void *context, uint64_t cblock, void *leaf)
908 {
909         int r = 0;
910         bool dirty;
911         __le64 value;
912         __le32 hint_value = 0;
913         dm_oblock_t oblock;
914         unsigned flags;
915         struct thunk *thunk = context;
916         struct dm_cache_metadata *cmd = thunk->cmd;
917
918         memcpy(&value, leaf, sizeof(value));
919         unpack_value(value, &oblock, &flags);
920
921         if (flags & M_VALID) {
922                 if (thunk->hints_valid) {
923                         r = dm_array_get_value(&cmd->hint_info, cmd->hint_root,
924                                                cblock, &hint_value);
925                         if (r && r != -ENODATA)
926                                 return r;
927                 }
928
929                 dirty = thunk->respect_dirty_flags ? (flags & M_DIRTY) : true;
930                 r = thunk->fn(thunk->context, oblock, to_cblock(cblock),
931                               dirty, le32_to_cpu(hint_value), thunk->hints_valid);
932         }
933
934         return r;
935 }
936
937 static int __load_mappings(struct dm_cache_metadata *cmd,
938                            struct dm_cache_policy *policy,
939                            load_mapping_fn fn, void *context)
940 {
941         struct thunk thunk;
942
943         thunk.fn = fn;
944         thunk.context = context;
945
946         thunk.cmd = cmd;
947         thunk.respect_dirty_flags = cmd->clean_when_opened;
948         thunk.hints_valid = hints_array_available(cmd, policy);
949
950         return dm_array_walk(&cmd->info, cmd->root, __load_mapping, &thunk);
951 }
952
953 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
954                            struct dm_cache_policy *policy,
955                            load_mapping_fn fn, void *context)
956 {
957         int r;
958
959         down_read(&cmd->root_lock);
960         r = __load_mappings(cmd, policy, fn, context);
961         up_read(&cmd->root_lock);
962
963         return r;
964 }
965
966 static int __dump_mapping(void *context, uint64_t cblock, void *leaf)
967 {
968         int r = 0;
969         __le64 value;
970         dm_oblock_t oblock;
971         unsigned flags;
972
973         memcpy(&value, leaf, sizeof(value));
974         unpack_value(value, &oblock, &flags);
975
976         return r;
977 }
978
979 static int __dump_mappings(struct dm_cache_metadata *cmd)
980 {
981         return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL);
982 }
983
984 void dm_cache_dump(struct dm_cache_metadata *cmd)
985 {
986         down_read(&cmd->root_lock);
987         __dump_mappings(cmd);
988         up_read(&cmd->root_lock);
989 }
990
991 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd)
992 {
993         int r;
994
995         down_read(&cmd->root_lock);
996         r = cmd->changed;
997         up_read(&cmd->root_lock);
998
999         return r;
1000 }
1001
1002 static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty)
1003 {
1004         int r;
1005         unsigned flags;
1006         dm_oblock_t oblock;
1007         __le64 value;
1008
1009         r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value);
1010         if (r)
1011                 return r;
1012
1013         unpack_value(value, &oblock, &flags);
1014
1015         if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty))
1016                 /* nothing to be done */
1017                 return 0;
1018
1019         value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
1020         __dm_bless_for_disk(&value);
1021
1022         r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
1023                                &value, &cmd->root);
1024         if (r)
1025                 return r;
1026
1027         cmd->changed = true;
1028         return 0;
1029
1030 }
1031
1032 int dm_cache_set_dirty(struct dm_cache_metadata *cmd,
1033                        dm_cblock_t cblock, bool dirty)
1034 {
1035         int r;
1036
1037         down_write(&cmd->root_lock);
1038         r = __dirty(cmd, cblock, dirty);
1039         up_write(&cmd->root_lock);
1040
1041         return r;
1042 }
1043
1044 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
1045                                  struct dm_cache_statistics *stats)
1046 {
1047         down_read(&cmd->root_lock);
1048         *stats = cmd->stats;
1049         up_read(&cmd->root_lock);
1050 }
1051
1052 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
1053                                  struct dm_cache_statistics *stats)
1054 {
1055         down_write(&cmd->root_lock);
1056         cmd->stats = *stats;
1057         up_write(&cmd->root_lock);
1058 }
1059
1060 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
1061 {
1062         int r;
1063         flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
1064                                  clear_clean_shutdown);
1065
1066         down_write(&cmd->root_lock);
1067         r = __commit_transaction(cmd, mutator);
1068         if (r)
1069                 goto out;
1070
1071         r = __begin_transaction(cmd);
1072
1073 out:
1074         up_write(&cmd->root_lock);
1075         return r;
1076 }
1077
1078 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
1079                                            dm_block_t *result)
1080 {
1081         int r = -EINVAL;
1082
1083         down_read(&cmd->root_lock);
1084         r = dm_sm_get_nr_free(cmd->metadata_sm, result);
1085         up_read(&cmd->root_lock);
1086
1087         return r;
1088 }
1089
1090 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
1091                                    dm_block_t *result)
1092 {
1093         int r = -EINVAL;
1094
1095         down_read(&cmd->root_lock);
1096         r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
1097         up_read(&cmd->root_lock);
1098
1099         return r;
1100 }
1101
1102 /*----------------------------------------------------------------*/
1103
1104 static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1105 {
1106         int r;
1107         __le32 value;
1108         size_t hint_size;
1109         const char *policy_name = dm_cache_policy_get_name(policy);
1110         const unsigned *policy_version = dm_cache_policy_get_version(policy);
1111
1112         if (!policy_name[0] ||
1113             (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
1114                 return -EINVAL;
1115
1116         if (!policy_unchanged(cmd, policy)) {
1117                 strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
1118                 memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
1119
1120                 hint_size = dm_cache_policy_get_hint_size(policy);
1121                 if (!hint_size)
1122                         return 0; /* short-circuit hints initialization */
1123                 cmd->policy_hint_size = hint_size;
1124
1125                 if (cmd->hint_root) {
1126                         r = dm_array_del(&cmd->hint_info, cmd->hint_root);
1127                         if (r)
1128                                 return r;
1129                 }
1130
1131                 r = dm_array_empty(&cmd->hint_info, &cmd->hint_root);
1132                 if (r)
1133                         return r;
1134
1135                 value = cpu_to_le32(0);
1136                 __dm_bless_for_disk(&value);
1137                 r = dm_array_resize(&cmd->hint_info, cmd->hint_root, 0,
1138                                     from_cblock(cmd->cache_blocks),
1139                                     &value, &cmd->hint_root);
1140                 if (r)
1141                         return r;
1142         }
1143
1144         return 0;
1145 }
1146
1147 int dm_cache_begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
1148 {
1149         int r;
1150
1151         down_write(&cmd->root_lock);
1152         r = begin_hints(cmd, policy);
1153         up_write(&cmd->root_lock);
1154
1155         return r;
1156 }
1157
1158 static int save_hint(struct dm_cache_metadata *cmd, dm_cblock_t cblock,
1159                      uint32_t hint)
1160 {
1161         int r;
1162         __le32 value = cpu_to_le32(hint);
1163         __dm_bless_for_disk(&value);
1164
1165         r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,
1166                                from_cblock(cblock), &value, &cmd->hint_root);
1167         cmd->changed = true;
1168
1169         return r;
1170 }
1171
1172 int dm_cache_save_hint(struct dm_cache_metadata *cmd, dm_cblock_t cblock,
1173                        uint32_t hint)
1174 {
1175         int r;
1176
1177         if (!hints_array_initialized(cmd))
1178                 return 0;
1179
1180         down_write(&cmd->root_lock);
1181         r = save_hint(cmd, cblock, hint);
1182         up_write(&cmd->root_lock);
1183
1184         return r;
1185 }