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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2019 Arrikto, Inc. All Rights Reserved.
4 */
5
6#include <linux/mm.h>
7#include <linux/err.h>
8#include <linux/slab.h>
9#include <linux/rwsem.h>
10#include <linux/bitops.h>
11#include <linux/bitmap.h>
12#include <linux/device-mapper.h>
13
14#include "persistent-data/dm-bitset.h"
15#include "persistent-data/dm-space-map.h"
16#include "persistent-data/dm-block-manager.h"
17#include "persistent-data/dm-transaction-manager.h"
18
19#include "dm-clone-metadata.h"
20
21#define DM_MSG_PREFIX "clone metadata"
22
23#define SUPERBLOCK_LOCATION 0
24#define SUPERBLOCK_MAGIC 0x8af27f64
25#define SUPERBLOCK_CSUM_XOR 257649492
26
27#define DM_CLONE_MAX_CONCURRENT_LOCKS 5
28
29#define UUID_LEN 16
30
31/* Min and max dm-clone metadata versions supported */
32#define DM_CLONE_MIN_METADATA_VERSION 1
33#define DM_CLONE_MAX_METADATA_VERSION 1
34
35/*
36 * On-disk metadata layout
37 */
38struct superblock_disk {
39 __le32 csum;
40 __le32 flags;
41 __le64 blocknr;
42
43 __u8 uuid[UUID_LEN];
44 __le64 magic;
45 __le32 version;
46
47 __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
48
49 __le64 region_size;
50 __le64 target_size;
51
52 __le64 bitset_root;
53} __packed;
54
55/*
56 * Region and Dirty bitmaps.
57 *
58 * dm-clone logically splits the source and destination devices in regions of
59 * fixed size. The destination device's regions are gradually hydrated, i.e.,
60 * we copy (clone) the source's regions to the destination device. Eventually,
61 * all regions will get hydrated and all I/O will be served from the
62 * destination device.
63 *
64 * We maintain an on-disk bitmap which tracks the state of each of the
65 * destination device's regions, i.e., whether they are hydrated or not.
66 *
67 * To save constantly doing look ups on disk we keep an in core copy of the
68 * on-disk bitmap, the region_map.
69 *
70 * In order to track which regions are hydrated during a metadata transaction,
71 * we use a second set of bitmaps, the dmap (dirty bitmap), which includes two
72 * bitmaps, namely dirty_regions and dirty_words. The dirty_regions bitmap
73 * tracks the regions that got hydrated during the current metadata
74 * transaction. The dirty_words bitmap tracks the dirty words, i.e. longs, of
75 * the dirty_regions bitmap.
76 *
77 * This allows us to precisely track the regions that were hydrated during the
78 * current metadata transaction and update the metadata accordingly, when we
79 * commit the current transaction. This is important because dm-clone should
80 * only commit the metadata of regions that were properly flushed to the
81 * destination device beforehand. Otherwise, in case of a crash, we could end
82 * up with a corrupted dm-clone device.
83 *
84 * When a region finishes hydrating dm-clone calls
85 * dm_clone_set_region_hydrated(), or for discard requests
86 * dm_clone_cond_set_range(), which sets the corresponding bits in region_map
87 * and dmap.
88 *
89 * During a metadata commit we scan dmap->dirty_words and dmap->dirty_regions
90 * and update the on-disk metadata accordingly. Thus, we don't have to flush to
91 * disk the whole region_map. We can just flush the dirty region_map bits.
92 *
93 * We use the helper dmap->dirty_words bitmap, which is smaller than the
94 * original region_map, to reduce the amount of memory accesses during a
95 * metadata commit. Moreover, as dm-bitset also accesses the on-disk bitmap in
96 * 64-bit word granularity, the dirty_words bitmap helps us avoid useless disk
97 * accesses.
98 *
99 * We could update directly the on-disk bitmap, when dm-clone calls either
100 * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), buts this
101 * inserts significant metadata I/O overhead in dm-clone's I/O path. Also, as
102 * these two functions don't block, we can call them in interrupt context,
103 * e.g., in a hooked overwrite bio's completion routine, and further reduce the
104 * I/O completion latency.
105 *
106 * We maintain two dirty bitmap sets. During a metadata commit we atomically
107 * swap the currently used dmap with the unused one. This allows the metadata
108 * update functions to run concurrently with an ongoing commit.
109 */
110struct dirty_map {
111 unsigned long *dirty_words;
112 unsigned long *dirty_regions;
113 unsigned int changed;
114};
115
116struct dm_clone_metadata {
117 /* The metadata block device */
118 struct block_device *bdev;
119
120 sector_t target_size;
121 sector_t region_size;
122 unsigned long nr_regions;
123 unsigned long nr_words;
124
125 /* Spinlock protecting the region and dirty bitmaps. */
126 spinlock_t bitmap_lock;
127 struct dirty_map dmap[2];
128 struct dirty_map *current_dmap;
129
130 /* Protected by lock */
131 struct dirty_map *committing_dmap;
132
133 /*
134 * In core copy of the on-disk bitmap to save constantly doing look ups
135 * on disk.
136 */
137 unsigned long *region_map;
138
139 /* Protected by bitmap_lock */
140 unsigned int read_only;
141
142 struct dm_block_manager *bm;
143 struct dm_space_map *sm;
144 struct dm_transaction_manager *tm;
145
146 struct rw_semaphore lock;
147
148 struct dm_disk_bitset bitset_info;
149 dm_block_t bitset_root;
150
151 /*
152 * Reading the space map root can fail, so we read it into this
153 * buffer before the superblock is locked and updated.
154 */
155 __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
156
157 bool hydration_done:1;
158 bool fail_io:1;
159};
160
161/*---------------------------------------------------------------------------*/
162
163/*
164 * Superblock validation.
165 */
166static void sb_prepare_for_write(struct dm_block_validator *v,
167 struct dm_block *b, size_t sb_block_size)
168{
169 struct superblock_disk *sb;
170 u32 csum;
171
172 sb = dm_block_data(b);
173 sb->blocknr = cpu_to_le64(dm_block_location(b));
174
175 csum = dm_bm_checksum(&sb->flags, sb_block_size - sizeof(__le32),
176 SUPERBLOCK_CSUM_XOR);
177 sb->csum = cpu_to_le32(csum);
178}
179
180static int sb_check(struct dm_block_validator *v, struct dm_block *b,
181 size_t sb_block_size)
182{
183 struct superblock_disk *sb;
184 u32 csum, metadata_version;
185
186 sb = dm_block_data(b);
187
188 if (dm_block_location(b) != le64_to_cpu(sb->blocknr)) {
189 DMERR("Superblock check failed: blocknr %llu, expected %llu",
190 le64_to_cpu(sb->blocknr),
191 (unsigned long long)dm_block_location(b));
192 return -ENOTBLK;
193 }
194
195 if (le64_to_cpu(sb->magic) != SUPERBLOCK_MAGIC) {
196 DMERR("Superblock check failed: magic %llu, expected %llu",
197 le64_to_cpu(sb->magic),
198 (unsigned long long)SUPERBLOCK_MAGIC);
199 return -EILSEQ;
200 }
201
202 csum = dm_bm_checksum(&sb->flags, sb_block_size - sizeof(__le32),
203 SUPERBLOCK_CSUM_XOR);
204 if (sb->csum != cpu_to_le32(csum)) {
205 DMERR("Superblock check failed: checksum %u, expected %u",
206 csum, le32_to_cpu(sb->csum));
207 return -EILSEQ;
208 }
209
210 /* Check metadata version */
211 metadata_version = le32_to_cpu(sb->version);
212 if (metadata_version < DM_CLONE_MIN_METADATA_VERSION ||
213 metadata_version > DM_CLONE_MAX_METADATA_VERSION) {
214 DMERR("Clone metadata version %u found, but only versions between %u and %u supported.",
215 metadata_version, DM_CLONE_MIN_METADATA_VERSION,
216 DM_CLONE_MAX_METADATA_VERSION);
217 return -EINVAL;
218 }
219
220 return 0;
221}
222
223static struct dm_block_validator sb_validator = {
224 .name = "superblock",
225 .prepare_for_write = sb_prepare_for_write,
226 .check = sb_check
227};
228
229/*
230 * Check if the superblock is formatted or not. We consider the superblock to
231 * be formatted in case we find non-zero bytes in it.
232 */
233static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *formatted)
234{
235 int r;
236 unsigned int i, nr_words;
237 struct dm_block *sblock;
238 __le64 *data_le, zero = cpu_to_le64(0);
239
240 /*
241 * We don't use a validator here because the superblock could be all
242 * zeroes.
243 */
244 r = dm_bm_read_lock(bm, SUPERBLOCK_LOCATION, NULL, &sblock);
245 if (r) {
246 DMERR("Failed to read_lock superblock");
247 return r;
248 }
249
250 data_le = dm_block_data(sblock);
251 *formatted = false;
252
253 /* This assumes that the block size is a multiple of 8 bytes */
254 BUG_ON(dm_bm_block_size(bm) % sizeof(__le64));
255 nr_words = dm_bm_block_size(bm) / sizeof(__le64);
256 for (i = 0; i < nr_words; i++) {
257 if (data_le[i] != zero) {
258 *formatted = true;
259 break;
260 }
261 }
262
263 dm_bm_unlock(sblock);
264
265 return 0;
266}
267
268/*---------------------------------------------------------------------------*/
269
270/*
271 * Low-level metadata handling.
272 */
273static inline int superblock_read_lock(struct dm_clone_metadata *cmd,
274 struct dm_block **sblock)
275{
276 return dm_bm_read_lock(cmd->bm, SUPERBLOCK_LOCATION, &sb_validator, sblock);
277}
278
279static inline int superblock_write_lock_zero(struct dm_clone_metadata *cmd,
280 struct dm_block **sblock)
281{
282 return dm_bm_write_lock_zero(cmd->bm, SUPERBLOCK_LOCATION, &sb_validator, sblock);
283}
284
285static int __copy_sm_root(struct dm_clone_metadata *cmd)
286{
287 int r;
288 size_t root_size;
289
290 r = dm_sm_root_size(cmd->sm, &root_size);
291 if (r)
292 return r;
293
294 return dm_sm_copy_root(cmd->sm, &cmd->metadata_space_map_root, root_size);
295}
296
297/* Save dm-clone metadata in superblock */
298static void __prepare_superblock(struct dm_clone_metadata *cmd,
299 struct superblock_disk *sb)
300{
301 sb->flags = cpu_to_le32(0UL);
302
303 /* FIXME: UUID is currently unused */
304 memset(sb->uuid, 0, sizeof(sb->uuid));
305
306 sb->magic = cpu_to_le64(SUPERBLOCK_MAGIC);
307 sb->version = cpu_to_le32(DM_CLONE_MAX_METADATA_VERSION);
308
309 /* Save the metadata space_map root */
310 memcpy(&sb->metadata_space_map_root, &cmd->metadata_space_map_root,
311 sizeof(cmd->metadata_space_map_root));
312
313 sb->region_size = cpu_to_le64(cmd->region_size);
314 sb->target_size = cpu_to_le64(cmd->target_size);
315 sb->bitset_root = cpu_to_le64(cmd->bitset_root);
316}
317
318static int __open_metadata(struct dm_clone_metadata *cmd)
319{
320 int r;
321 struct dm_block *sblock;
322 struct superblock_disk *sb;
323
324 r = superblock_read_lock(cmd, &sblock);
325
326 if (r) {
327 DMERR("Failed to read_lock superblock");
328 return r;
329 }
330
331 sb = dm_block_data(sblock);
332
333 /* Verify that target_size and region_size haven't changed. */
334 if (cmd->region_size != le64_to_cpu(sb->region_size) ||
335 cmd->target_size != le64_to_cpu(sb->target_size)) {
336 DMERR("Region and/or target size don't match the ones in metadata");
337 r = -EINVAL;
338 goto out_with_lock;
339 }
340
341 r = dm_tm_open_with_sm(cmd->bm, SUPERBLOCK_LOCATION,
342 sb->metadata_space_map_root,
343 sizeof(sb->metadata_space_map_root),
344 &cmd->tm, &cmd->sm);
345
346 if (r) {
347 DMERR("dm_tm_open_with_sm failed");
348 goto out_with_lock;
349 }
350
351 dm_disk_bitset_init(cmd->tm, &cmd->bitset_info);
352 cmd->bitset_root = le64_to_cpu(sb->bitset_root);
353
354out_with_lock:
355 dm_bm_unlock(sblock);
356
357 return r;
358}
359
360static int __format_metadata(struct dm_clone_metadata *cmd)
361{
362 int r;
363 struct dm_block *sblock;
364 struct superblock_disk *sb;
365
366 r = dm_tm_create_with_sm(cmd->bm, SUPERBLOCK_LOCATION, &cmd->tm, &cmd->sm);
367 if (r) {
368 DMERR("Failed to create transaction manager");
369 return r;
370 }
371
372 dm_disk_bitset_init(cmd->tm, &cmd->bitset_info);
373
374 r = dm_bitset_empty(&cmd->bitset_info, &cmd->bitset_root);
375 if (r) {
376 DMERR("Failed to create empty on-disk bitset");
377 goto err_with_tm;
378 }
379
380 r = dm_bitset_resize(&cmd->bitset_info, cmd->bitset_root, 0,
381 cmd->nr_regions, false, &cmd->bitset_root);
382 if (r) {
383 DMERR("Failed to resize on-disk bitset to %lu entries", cmd->nr_regions);
384 goto err_with_tm;
385 }
386
387 /* Flush to disk all blocks, except the superblock */
388 r = dm_tm_pre_commit(cmd->tm);
389 if (r) {
390 DMERR("dm_tm_pre_commit failed");
391 goto err_with_tm;
392 }
393
394 r = __copy_sm_root(cmd);
395 if (r) {
396 DMERR("__copy_sm_root failed");
397 goto err_with_tm;
398 }
399
400 r = superblock_write_lock_zero(cmd, &sblock);
401 if (r) {
402 DMERR("Failed to write_lock superblock");
403 goto err_with_tm;
404 }
405
406 sb = dm_block_data(sblock);
407 __prepare_superblock(cmd, sb);
408 r = dm_tm_commit(cmd->tm, sblock);
409 if (r) {
410 DMERR("Failed to commit superblock");
411 goto err_with_tm;
412 }
413
414 return 0;
415
416err_with_tm:
417 dm_sm_destroy(cmd->sm);
418 dm_tm_destroy(cmd->tm);
419
420 return r;
421}
422
423static int __open_or_format_metadata(struct dm_clone_metadata *cmd, bool may_format_device)
424{
425 int r;
426 bool formatted = false;
427
428 r = __superblock_all_zeroes(cmd->bm, &formatted);
429 if (r)
430 return r;
431
432 if (!formatted)
433 return may_format_device ? __format_metadata(cmd) : -EPERM;
434
435 return __open_metadata(cmd);
436}
437
438static int __create_persistent_data_structures(struct dm_clone_metadata *cmd,
439 bool may_format_device)
440{
441 int r;
442
443 /* Create block manager */
444 cmd->bm = dm_block_manager_create(cmd->bdev,
445 DM_CLONE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
446 DM_CLONE_MAX_CONCURRENT_LOCKS);
447 if (IS_ERR(cmd->bm)) {
448 DMERR("Failed to create block manager");
449 return PTR_ERR(cmd->bm);
450 }
451
452 r = __open_or_format_metadata(cmd, may_format_device);
453 if (r)
454 dm_block_manager_destroy(cmd->bm);
455
456 return r;
457}
458
459static void __destroy_persistent_data_structures(struct dm_clone_metadata *cmd)
460{
461 dm_sm_destroy(cmd->sm);
462 dm_tm_destroy(cmd->tm);
463 dm_block_manager_destroy(cmd->bm);
464}
465
466/*---------------------------------------------------------------------------*/
467
468static size_t bitmap_size(unsigned long nr_bits)
469{
470 return BITS_TO_LONGS(nr_bits) * sizeof(long);
471}
472
473static int __dirty_map_init(struct dirty_map *dmap, unsigned long nr_words,
474 unsigned long nr_regions)
475{
476 dmap->changed = 0;
477
478 dmap->dirty_words = kvzalloc(bitmap_size(nr_words), GFP_KERNEL);
479 if (!dmap->dirty_words)
480 return -ENOMEM;
481
482 dmap->dirty_regions = kvzalloc(bitmap_size(nr_regions), GFP_KERNEL);
483 if (!dmap->dirty_regions) {
484 kvfree(dmap->dirty_words);
485 return -ENOMEM;
486 }
487
488 return 0;
489}
490
491static void __dirty_map_exit(struct dirty_map *dmap)
492{
493 kvfree(dmap->dirty_words);
494 kvfree(dmap->dirty_regions);
495}
496
497static int dirty_map_init(struct dm_clone_metadata *cmd)
498{
499 if (__dirty_map_init(&cmd->dmap[0], cmd->nr_words, cmd->nr_regions)) {
500 DMERR("Failed to allocate dirty bitmap");
501 return -ENOMEM;
502 }
503
504 if (__dirty_map_init(&cmd->dmap[1], cmd->nr_words, cmd->nr_regions)) {
505 DMERR("Failed to allocate dirty bitmap");
506 __dirty_map_exit(&cmd->dmap[0]);
507 return -ENOMEM;
508 }
509
510 cmd->current_dmap = &cmd->dmap[0];
511 cmd->committing_dmap = NULL;
512
513 return 0;
514}
515
516static void dirty_map_exit(struct dm_clone_metadata *cmd)
517{
518 __dirty_map_exit(&cmd->dmap[0]);
519 __dirty_map_exit(&cmd->dmap[1]);
520}
521
522static int __load_bitset_in_core(struct dm_clone_metadata *cmd)
523{
524 int r;
525 unsigned long i;
526 struct dm_bitset_cursor c;
527
528 /* Flush bitset cache */
529 r = dm_bitset_flush(&cmd->bitset_info, cmd->bitset_root, &cmd->bitset_root);
530 if (r)
531 return r;
532
533 r = dm_bitset_cursor_begin(&cmd->bitset_info, cmd->bitset_root, cmd->nr_regions, &c);
534 if (r)
535 return r;
536
537 for (i = 0; ; i++) {
538 if (dm_bitset_cursor_get_value(&c))
539 __set_bit(i, cmd->region_map);
540 else
541 __clear_bit(i, cmd->region_map);
542
543 if (i >= (cmd->nr_regions - 1))
544 break;
545
546 r = dm_bitset_cursor_next(&c);
547
548 if (r)
549 break;
550 }
551
552 dm_bitset_cursor_end(&c);
553
554 return r;
555}
556
557struct dm_clone_metadata *dm_clone_metadata_open(struct block_device *bdev,
558 sector_t target_size,
559 sector_t region_size)
560{
561 int r;
562 struct dm_clone_metadata *cmd;
563
564 cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
565 if (!cmd) {
566 DMERR("Failed to allocate memory for dm-clone metadata");
567 return ERR_PTR(-ENOMEM);
568 }
569
570 cmd->bdev = bdev;
571 cmd->target_size = target_size;
572 cmd->region_size = region_size;
573 cmd->nr_regions = dm_sector_div_up(cmd->target_size, cmd->region_size);
574 cmd->nr_words = BITS_TO_LONGS(cmd->nr_regions);
575
576 init_rwsem(&cmd->lock);
577 spin_lock_init(&cmd->bitmap_lock);
578 cmd->read_only = 0;
579 cmd->fail_io = false;
580 cmd->hydration_done = false;
581
582 cmd->region_map = kvmalloc(bitmap_size(cmd->nr_regions), GFP_KERNEL);
583 if (!cmd->region_map) {
584 DMERR("Failed to allocate memory for region bitmap");
585 r = -ENOMEM;
586 goto out_with_md;
587 }
588
589 r = __create_persistent_data_structures(cmd, true);
590 if (r)
591 goto out_with_region_map;
592
593 r = __load_bitset_in_core(cmd);
594 if (r) {
595 DMERR("Failed to load on-disk region map");
596 goto out_with_pds;
597 }
598
599 r = dirty_map_init(cmd);
600 if (r)
601 goto out_with_pds;
602
603 if (bitmap_full(cmd->region_map, cmd->nr_regions))
604 cmd->hydration_done = true;
605
606 return cmd;
607
608out_with_pds:
609 __destroy_persistent_data_structures(cmd);
610
611out_with_region_map:
612 kvfree(cmd->region_map);
613
614out_with_md:
615 kfree(cmd);
616
617 return ERR_PTR(r);
618}
619
620void dm_clone_metadata_close(struct dm_clone_metadata *cmd)
621{
622 if (!cmd->fail_io)
623 __destroy_persistent_data_structures(cmd);
624
625 dirty_map_exit(cmd);
626 kvfree(cmd->region_map);
627 kfree(cmd);
628}
629
630bool dm_clone_is_hydration_done(struct dm_clone_metadata *cmd)
631{
632 return cmd->hydration_done;
633}
634
635bool dm_clone_is_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr)
636{
637 return dm_clone_is_hydration_done(cmd) || test_bit(region_nr, cmd->region_map);
638}
639
640bool dm_clone_is_range_hydrated(struct dm_clone_metadata *cmd,
641 unsigned long start, unsigned long nr_regions)
642{
643 unsigned long bit;
644
645 if (dm_clone_is_hydration_done(cmd))
646 return true;
647
648 bit = find_next_zero_bit(cmd->region_map, cmd->nr_regions, start);
649
650 return (bit >= (start + nr_regions));
651}
652
653unsigned int dm_clone_nr_of_hydrated_regions(struct dm_clone_metadata *cmd)
654{
655 return bitmap_weight(cmd->region_map, cmd->nr_regions);
656}
657
658unsigned long dm_clone_find_next_unhydrated_region(struct dm_clone_metadata *cmd,
659 unsigned long start)
660{
661 return find_next_zero_bit(cmd->region_map, cmd->nr_regions, start);
662}
663
664static int __update_metadata_word(struct dm_clone_metadata *cmd,
665 unsigned long *dirty_regions,
666 unsigned long word)
667{
668 int r;
669 unsigned long index = word * BITS_PER_LONG;
670 unsigned long max_index = min(cmd->nr_regions, (word + 1) * BITS_PER_LONG);
671
672 while (index < max_index) {
673 if (test_bit(index, dirty_regions)) {
674 r = dm_bitset_set_bit(&cmd->bitset_info, cmd->bitset_root,
675 index, &cmd->bitset_root);
676 if (r) {
677 DMERR("dm_bitset_set_bit failed");
678 return r;
679 }
680 __clear_bit(index, dirty_regions);
681 }
682 index++;
683 }
684
685 return 0;
686}
687
688static int __metadata_commit(struct dm_clone_metadata *cmd)
689{
690 int r;
691 struct dm_block *sblock;
692 struct superblock_disk *sb;
693
694 /* Flush bitset cache */
695 r = dm_bitset_flush(&cmd->bitset_info, cmd->bitset_root, &cmd->bitset_root);
696 if (r) {
697 DMERR("dm_bitset_flush failed");
698 return r;
699 }
700
701 /* Flush to disk all blocks, except the superblock */
702 r = dm_tm_pre_commit(cmd->tm);
703 if (r) {
704 DMERR("dm_tm_pre_commit failed");
705 return r;
706 }
707
708 /* Save the space map root in cmd->metadata_space_map_root */
709 r = __copy_sm_root(cmd);
710 if (r) {
711 DMERR("__copy_sm_root failed");
712 return r;
713 }
714
715 /* Lock the superblock */
716 r = superblock_write_lock_zero(cmd, &sblock);
717 if (r) {
718 DMERR("Failed to write_lock superblock");
719 return r;
720 }
721
722 /* Save the metadata in superblock */
723 sb = dm_block_data(sblock);
724 __prepare_superblock(cmd, sb);
725
726 /* Unlock superblock and commit it to disk */
727 r = dm_tm_commit(cmd->tm, sblock);
728 if (r) {
729 DMERR("Failed to commit superblock");
730 return r;
731 }
732
733 /*
734 * FIXME: Find a more efficient way to check if the hydration is done.
735 */
736 if (bitmap_full(cmd->region_map, cmd->nr_regions))
737 cmd->hydration_done = true;
738
739 return 0;
740}
741
742static int __flush_dmap(struct dm_clone_metadata *cmd, struct dirty_map *dmap)
743{
744 int r;
745 unsigned long word;
746
747 word = 0;
748 do {
749 word = find_next_bit(dmap->dirty_words, cmd->nr_words, word);
750
751 if (word == cmd->nr_words)
752 break;
753
754 r = __update_metadata_word(cmd, dmap->dirty_regions, word);
755
756 if (r)
757 return r;
758
759 __clear_bit(word, dmap->dirty_words);
760 word++;
761 } while (word < cmd->nr_words);
762
763 r = __metadata_commit(cmd);
764
765 if (r)
766 return r;
767
768 /* Update the changed flag */
769 spin_lock_irq(&cmd->bitmap_lock);
770 dmap->changed = 0;
771 spin_unlock_irq(&cmd->bitmap_lock);
772
773 return 0;
774}
775
776int dm_clone_metadata_pre_commit(struct dm_clone_metadata *cmd)
777{
778 int r = 0;
779 struct dirty_map *dmap, *next_dmap;
780
781 down_write(&cmd->lock);
782
783 if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
784 r = -EPERM;
785 goto out;
786 }
787
788 /* Get current dirty bitmap */
789 dmap = cmd->current_dmap;
790
791 /* Get next dirty bitmap */
792 next_dmap = (dmap == &cmd->dmap[0]) ? &cmd->dmap[1] : &cmd->dmap[0];
793
794 /*
795 * The last commit failed, so we don't have a clean dirty-bitmap to
796 * use.
797 */
798 if (WARN_ON(next_dmap->changed || cmd->committing_dmap)) {
799 r = -EINVAL;
800 goto out;
801 }
802
803 /* Swap dirty bitmaps */
804 spin_lock_irq(&cmd->bitmap_lock);
805 cmd->current_dmap = next_dmap;
806 spin_unlock_irq(&cmd->bitmap_lock);
807
808 /* Set old dirty bitmap as currently committing */
809 cmd->committing_dmap = dmap;
810out:
811 up_write(&cmd->lock);
812
813 return r;
814}
815
816int dm_clone_metadata_commit(struct dm_clone_metadata *cmd)
817{
818 int r = -EPERM;
819
820 down_write(&cmd->lock);
821
822 if (cmd->fail_io || dm_bm_is_read_only(cmd->bm))
823 goto out;
824
825 if (WARN_ON(!cmd->committing_dmap)) {
826 r = -EINVAL;
827 goto out;
828 }
829
830 r = __flush_dmap(cmd, cmd->committing_dmap);
831 if (!r) {
832 /* Clear committing dmap */
833 cmd->committing_dmap = NULL;
834 }
835out:
836 up_write(&cmd->lock);
837
838 return r;
839}
840
841int dm_clone_set_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr)
842{
843 int r = 0;
844 struct dirty_map *dmap;
845 unsigned long word, flags;
846
847 if (unlikely(region_nr >= cmd->nr_regions)) {
848 DMERR("Region %lu out of range (total number of regions %lu)",
849 region_nr, cmd->nr_regions);
850 return -ERANGE;
851 }
852
853 word = region_nr / BITS_PER_LONG;
854
855 spin_lock_irqsave(&cmd->bitmap_lock, flags);
856
857 if (cmd->read_only) {
858 r = -EPERM;
859 goto out;
860 }
861
862 dmap = cmd->current_dmap;
863
864 __set_bit(word, dmap->dirty_words);
865 __set_bit(region_nr, dmap->dirty_regions);
866 __set_bit(region_nr, cmd->region_map);
867 dmap->changed = 1;
868
869out:
870 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
871
872 return r;
873}
874
875int dm_clone_cond_set_range(struct dm_clone_metadata *cmd, unsigned long start,
876 unsigned long nr_regions)
877{
878 int r = 0;
879 struct dirty_map *dmap;
880 unsigned long word, region_nr;
881
882 if (unlikely(start >= cmd->nr_regions || (start + nr_regions) < start ||
883 (start + nr_regions) > cmd->nr_regions)) {
884 DMERR("Invalid region range: start %lu, nr_regions %lu (total number of regions %lu)",
885 start, nr_regions, cmd->nr_regions);
886 return -ERANGE;
887 }
888
889 spin_lock_irq(&cmd->bitmap_lock);
890
891 if (cmd->read_only) {
892 r = -EPERM;
893 goto out;
894 }
895
896 dmap = cmd->current_dmap;
897 for (region_nr = start; region_nr < (start + nr_regions); region_nr++) {
898 if (!test_bit(region_nr, cmd->region_map)) {
899 word = region_nr / BITS_PER_LONG;
900 __set_bit(word, dmap->dirty_words);
901 __set_bit(region_nr, dmap->dirty_regions);
902 __set_bit(region_nr, cmd->region_map);
903 dmap->changed = 1;
904 }
905 }
906out:
907 spin_unlock_irq(&cmd->bitmap_lock);
908
909 return r;
910}
911
912/*
913 * WARNING: This must not be called concurrently with either
914 * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), as it changes
915 * cmd->region_map without taking the cmd->bitmap_lock spinlock. The only
916 * exception is after setting the metadata to read-only mode, using
917 * dm_clone_metadata_set_read_only().
918 *
919 * We don't take the spinlock because __load_bitset_in_core() does I/O, so it
920 * may block.
921 */
922int dm_clone_reload_in_core_bitset(struct dm_clone_metadata *cmd)
923{
924 int r = -EINVAL;
925
926 down_write(&cmd->lock);
927
928 if (cmd->fail_io)
929 goto out;
930
931 r = __load_bitset_in_core(cmd);
932out:
933 up_write(&cmd->lock);
934
935 return r;
936}
937
938bool dm_clone_changed_this_transaction(struct dm_clone_metadata *cmd)
939{
940 bool r;
941 unsigned long flags;
942
943 spin_lock_irqsave(&cmd->bitmap_lock, flags);
944 r = cmd->dmap[0].changed || cmd->dmap[1].changed;
945 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
946
947 return r;
948}
949
950int dm_clone_metadata_abort(struct dm_clone_metadata *cmd)
951{
952 int r = -EPERM;
953
954 down_write(&cmd->lock);
955
956 if (cmd->fail_io || dm_bm_is_read_only(cmd->bm))
957 goto out;
958
959 __destroy_persistent_data_structures(cmd);
960
961 r = __create_persistent_data_structures(cmd, false);
962 if (r) {
963 /* If something went wrong we can neither write nor read the metadata */
964 cmd->fail_io = true;
965 }
966out:
967 up_write(&cmd->lock);
968
969 return r;
970}
971
972void dm_clone_metadata_set_read_only(struct dm_clone_metadata *cmd)
973{
974 down_write(&cmd->lock);
975
976 spin_lock_irq(&cmd->bitmap_lock);
977 cmd->read_only = 1;
978 spin_unlock_irq(&cmd->bitmap_lock);
979
980 if (!cmd->fail_io)
981 dm_bm_set_read_only(cmd->bm);
982
983 up_write(&cmd->lock);
984}
985
986void dm_clone_metadata_set_read_write(struct dm_clone_metadata *cmd)
987{
988 down_write(&cmd->lock);
989
990 spin_lock_irq(&cmd->bitmap_lock);
991 cmd->read_only = 0;
992 spin_unlock_irq(&cmd->bitmap_lock);
993
994 if (!cmd->fail_io)
995 dm_bm_set_read_write(cmd->bm);
996
997 up_write(&cmd->lock);
998}
999
1000int dm_clone_get_free_metadata_block_count(struct dm_clone_metadata *cmd,
1001 dm_block_t *result)
1002{
1003 int r = -EINVAL;
1004
1005 down_read(&cmd->lock);
1006
1007 if (!cmd->fail_io)
1008 r = dm_sm_get_nr_free(cmd->sm, result);
1009
1010 up_read(&cmd->lock);
1011
1012 return r;
1013}
1014
1015int dm_clone_get_metadata_dev_size(struct dm_clone_metadata *cmd,
1016 dm_block_t *result)
1017{
1018 int r = -EINVAL;
1019
1020 down_read(&cmd->lock);
1021
1022 if (!cmd->fail_io)
1023 r = dm_sm_get_nr_blocks(cmd->sm, result);
1024
1025 up_read(&cmd->lock);
1026
1027 return r;
1028}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2019 Arrikto, Inc. All Rights Reserved.
4 */
5
6#include <linux/mm.h>
7#include <linux/err.h>
8#include <linux/slab.h>
9#include <linux/rwsem.h>
10#include <linux/bitops.h>
11#include <linux/bitmap.h>
12#include <linux/device-mapper.h>
13
14#include "persistent-data/dm-bitset.h"
15#include "persistent-data/dm-space-map.h"
16#include "persistent-data/dm-block-manager.h"
17#include "persistent-data/dm-transaction-manager.h"
18
19#include "dm-clone-metadata.h"
20
21#define DM_MSG_PREFIX "clone metadata"
22
23#define SUPERBLOCK_LOCATION 0
24#define SUPERBLOCK_MAGIC 0x8af27f64
25#define SUPERBLOCK_CSUM_XOR 257649492
26
27#define DM_CLONE_MAX_CONCURRENT_LOCKS 5
28
29#define UUID_LEN 16
30
31/* Min and max dm-clone metadata versions supported */
32#define DM_CLONE_MIN_METADATA_VERSION 1
33#define DM_CLONE_MAX_METADATA_VERSION 1
34
35/*
36 * On-disk metadata layout
37 */
38struct superblock_disk {
39 __le32 csum;
40 __le32 flags;
41 __le64 blocknr;
42
43 __u8 uuid[UUID_LEN];
44 __le64 magic;
45 __le32 version;
46
47 __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
48
49 __le64 region_size;
50 __le64 target_size;
51
52 __le64 bitset_root;
53} __packed;
54
55/*
56 * Region and Dirty bitmaps.
57 *
58 * dm-clone logically splits the source and destination devices in regions of
59 * fixed size. The destination device's regions are gradually hydrated, i.e.,
60 * we copy (clone) the source's regions to the destination device. Eventually,
61 * all regions will get hydrated and all I/O will be served from the
62 * destination device.
63 *
64 * We maintain an on-disk bitmap which tracks the state of each of the
65 * destination device's regions, i.e., whether they are hydrated or not.
66 *
67 * To save constantly doing look ups on disk we keep an in core copy of the
68 * on-disk bitmap, the region_map.
69 *
70 * To further reduce metadata I/O overhead we use a second bitmap, the dmap
71 * (dirty bitmap), which tracks the dirty words, i.e. longs, of the region_map.
72 *
73 * When a region finishes hydrating dm-clone calls
74 * dm_clone_set_region_hydrated(), or for discard requests
75 * dm_clone_cond_set_range(), which sets the corresponding bits in region_map
76 * and dmap.
77 *
78 * During a metadata commit we scan the dmap for dirty region_map words (longs)
79 * and update accordingly the on-disk metadata. Thus, we don't have to flush to
80 * disk the whole region_map. We can just flush the dirty region_map words.
81 *
82 * We use a dirty bitmap, which is smaller than the original region_map, to
83 * reduce the amount of memory accesses during a metadata commit. As dm-bitset
84 * accesses the on-disk bitmap in 64-bit word granularity, there is no
85 * significant benefit in tracking the dirty region_map bits with a smaller
86 * granularity.
87 *
88 * We could update directly the on-disk bitmap, when dm-clone calls either
89 * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), buts this
90 * inserts significant metadata I/O overhead in dm-clone's I/O path. Also, as
91 * these two functions don't block, we can call them in interrupt context,
92 * e.g., in a hooked overwrite bio's completion routine, and further reduce the
93 * I/O completion latency.
94 *
95 * We maintain two dirty bitmaps. During a metadata commit we atomically swap
96 * the currently used dmap with the unused one. This allows the metadata update
97 * functions to run concurrently with an ongoing commit.
98 */
99struct dirty_map {
100 unsigned long *dirty_words;
101 unsigned int changed;
102};
103
104struct dm_clone_metadata {
105 /* The metadata block device */
106 struct block_device *bdev;
107
108 sector_t target_size;
109 sector_t region_size;
110 unsigned long nr_regions;
111 unsigned long nr_words;
112
113 /* Spinlock protecting the region and dirty bitmaps. */
114 spinlock_t bitmap_lock;
115 struct dirty_map dmap[2];
116 struct dirty_map *current_dmap;
117
118 /*
119 * In core copy of the on-disk bitmap to save constantly doing look ups
120 * on disk.
121 */
122 unsigned long *region_map;
123
124 /* Protected by bitmap_lock */
125 unsigned int read_only;
126
127 struct dm_block_manager *bm;
128 struct dm_space_map *sm;
129 struct dm_transaction_manager *tm;
130
131 struct rw_semaphore lock;
132
133 struct dm_disk_bitset bitset_info;
134 dm_block_t bitset_root;
135
136 /*
137 * Reading the space map root can fail, so we read it into this
138 * buffer before the superblock is locked and updated.
139 */
140 __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
141
142 bool hydration_done:1;
143 bool fail_io:1;
144};
145
146/*---------------------------------------------------------------------------*/
147
148/*
149 * Superblock validation.
150 */
151static void sb_prepare_for_write(struct dm_block_validator *v,
152 struct dm_block *b, size_t sb_block_size)
153{
154 struct superblock_disk *sb;
155 u32 csum;
156
157 sb = dm_block_data(b);
158 sb->blocknr = cpu_to_le64(dm_block_location(b));
159
160 csum = dm_bm_checksum(&sb->flags, sb_block_size - sizeof(__le32),
161 SUPERBLOCK_CSUM_XOR);
162 sb->csum = cpu_to_le32(csum);
163}
164
165static int sb_check(struct dm_block_validator *v, struct dm_block *b,
166 size_t sb_block_size)
167{
168 struct superblock_disk *sb;
169 u32 csum, metadata_version;
170
171 sb = dm_block_data(b);
172
173 if (dm_block_location(b) != le64_to_cpu(sb->blocknr)) {
174 DMERR("Superblock check failed: blocknr %llu, expected %llu",
175 le64_to_cpu(sb->blocknr),
176 (unsigned long long)dm_block_location(b));
177 return -ENOTBLK;
178 }
179
180 if (le64_to_cpu(sb->magic) != SUPERBLOCK_MAGIC) {
181 DMERR("Superblock check failed: magic %llu, expected %llu",
182 le64_to_cpu(sb->magic),
183 (unsigned long long)SUPERBLOCK_MAGIC);
184 return -EILSEQ;
185 }
186
187 csum = dm_bm_checksum(&sb->flags, sb_block_size - sizeof(__le32),
188 SUPERBLOCK_CSUM_XOR);
189 if (sb->csum != cpu_to_le32(csum)) {
190 DMERR("Superblock check failed: checksum %u, expected %u",
191 csum, le32_to_cpu(sb->csum));
192 return -EILSEQ;
193 }
194
195 /* Check metadata version */
196 metadata_version = le32_to_cpu(sb->version);
197 if (metadata_version < DM_CLONE_MIN_METADATA_VERSION ||
198 metadata_version > DM_CLONE_MAX_METADATA_VERSION) {
199 DMERR("Clone metadata version %u found, but only versions between %u and %u supported.",
200 metadata_version, DM_CLONE_MIN_METADATA_VERSION,
201 DM_CLONE_MAX_METADATA_VERSION);
202 return -EINVAL;
203 }
204
205 return 0;
206}
207
208static struct dm_block_validator sb_validator = {
209 .name = "superblock",
210 .prepare_for_write = sb_prepare_for_write,
211 .check = sb_check
212};
213
214/*
215 * Check if the superblock is formatted or not. We consider the superblock to
216 * be formatted in case we find non-zero bytes in it.
217 */
218static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *formatted)
219{
220 int r;
221 unsigned int i, nr_words;
222 struct dm_block *sblock;
223 __le64 *data_le, zero = cpu_to_le64(0);
224
225 /*
226 * We don't use a validator here because the superblock could be all
227 * zeroes.
228 */
229 r = dm_bm_read_lock(bm, SUPERBLOCK_LOCATION, NULL, &sblock);
230 if (r) {
231 DMERR("Failed to read_lock superblock");
232 return r;
233 }
234
235 data_le = dm_block_data(sblock);
236 *formatted = false;
237
238 /* This assumes that the block size is a multiple of 8 bytes */
239 BUG_ON(dm_bm_block_size(bm) % sizeof(__le64));
240 nr_words = dm_bm_block_size(bm) / sizeof(__le64);
241 for (i = 0; i < nr_words; i++) {
242 if (data_le[i] != zero) {
243 *formatted = true;
244 break;
245 }
246 }
247
248 dm_bm_unlock(sblock);
249
250 return 0;
251}
252
253/*---------------------------------------------------------------------------*/
254
255/*
256 * Low-level metadata handling.
257 */
258static inline int superblock_read_lock(struct dm_clone_metadata *cmd,
259 struct dm_block **sblock)
260{
261 return dm_bm_read_lock(cmd->bm, SUPERBLOCK_LOCATION, &sb_validator, sblock);
262}
263
264static inline int superblock_write_lock(struct dm_clone_metadata *cmd,
265 struct dm_block **sblock)
266{
267 return dm_bm_write_lock(cmd->bm, SUPERBLOCK_LOCATION, &sb_validator, sblock);
268}
269
270static inline int superblock_write_lock_zero(struct dm_clone_metadata *cmd,
271 struct dm_block **sblock)
272{
273 return dm_bm_write_lock_zero(cmd->bm, SUPERBLOCK_LOCATION, &sb_validator, sblock);
274}
275
276static int __copy_sm_root(struct dm_clone_metadata *cmd)
277{
278 int r;
279 size_t root_size;
280
281 r = dm_sm_root_size(cmd->sm, &root_size);
282 if (r)
283 return r;
284
285 return dm_sm_copy_root(cmd->sm, &cmd->metadata_space_map_root, root_size);
286}
287
288/* Save dm-clone metadata in superblock */
289static void __prepare_superblock(struct dm_clone_metadata *cmd,
290 struct superblock_disk *sb)
291{
292 sb->flags = cpu_to_le32(0UL);
293
294 /* FIXME: UUID is currently unused */
295 memset(sb->uuid, 0, sizeof(sb->uuid));
296
297 sb->magic = cpu_to_le64(SUPERBLOCK_MAGIC);
298 sb->version = cpu_to_le32(DM_CLONE_MAX_METADATA_VERSION);
299
300 /* Save the metadata space_map root */
301 memcpy(&sb->metadata_space_map_root, &cmd->metadata_space_map_root,
302 sizeof(cmd->metadata_space_map_root));
303
304 sb->region_size = cpu_to_le64(cmd->region_size);
305 sb->target_size = cpu_to_le64(cmd->target_size);
306 sb->bitset_root = cpu_to_le64(cmd->bitset_root);
307}
308
309static int __open_metadata(struct dm_clone_metadata *cmd)
310{
311 int r;
312 struct dm_block *sblock;
313 struct superblock_disk *sb;
314
315 r = superblock_read_lock(cmd, &sblock);
316
317 if (r) {
318 DMERR("Failed to read_lock superblock");
319 return r;
320 }
321
322 sb = dm_block_data(sblock);
323
324 /* Verify that target_size and region_size haven't changed. */
325 if (cmd->region_size != le64_to_cpu(sb->region_size) ||
326 cmd->target_size != le64_to_cpu(sb->target_size)) {
327 DMERR("Region and/or target size don't match the ones in metadata");
328 r = -EINVAL;
329 goto out_with_lock;
330 }
331
332 r = dm_tm_open_with_sm(cmd->bm, SUPERBLOCK_LOCATION,
333 sb->metadata_space_map_root,
334 sizeof(sb->metadata_space_map_root),
335 &cmd->tm, &cmd->sm);
336
337 if (r) {
338 DMERR("dm_tm_open_with_sm failed");
339 goto out_with_lock;
340 }
341
342 dm_disk_bitset_init(cmd->tm, &cmd->bitset_info);
343 cmd->bitset_root = le64_to_cpu(sb->bitset_root);
344
345out_with_lock:
346 dm_bm_unlock(sblock);
347
348 return r;
349}
350
351static int __format_metadata(struct dm_clone_metadata *cmd)
352{
353 int r;
354 struct dm_block *sblock;
355 struct superblock_disk *sb;
356
357 r = dm_tm_create_with_sm(cmd->bm, SUPERBLOCK_LOCATION, &cmd->tm, &cmd->sm);
358 if (r) {
359 DMERR("Failed to create transaction manager");
360 return r;
361 }
362
363 dm_disk_bitset_init(cmd->tm, &cmd->bitset_info);
364
365 r = dm_bitset_empty(&cmd->bitset_info, &cmd->bitset_root);
366 if (r) {
367 DMERR("Failed to create empty on-disk bitset");
368 goto err_with_tm;
369 }
370
371 r = dm_bitset_resize(&cmd->bitset_info, cmd->bitset_root, 0,
372 cmd->nr_regions, false, &cmd->bitset_root);
373 if (r) {
374 DMERR("Failed to resize on-disk bitset to %lu entries", cmd->nr_regions);
375 goto err_with_tm;
376 }
377
378 /* Flush to disk all blocks, except the superblock */
379 r = dm_tm_pre_commit(cmd->tm);
380 if (r) {
381 DMERR("dm_tm_pre_commit failed");
382 goto err_with_tm;
383 }
384
385 r = __copy_sm_root(cmd);
386 if (r) {
387 DMERR("__copy_sm_root failed");
388 goto err_with_tm;
389 }
390
391 r = superblock_write_lock_zero(cmd, &sblock);
392 if (r) {
393 DMERR("Failed to write_lock superblock");
394 goto err_with_tm;
395 }
396
397 sb = dm_block_data(sblock);
398 __prepare_superblock(cmd, sb);
399 r = dm_tm_commit(cmd->tm, sblock);
400 if (r) {
401 DMERR("Failed to commit superblock");
402 goto err_with_tm;
403 }
404
405 return 0;
406
407err_with_tm:
408 dm_sm_destroy(cmd->sm);
409 dm_tm_destroy(cmd->tm);
410
411 return r;
412}
413
414static int __open_or_format_metadata(struct dm_clone_metadata *cmd, bool may_format_device)
415{
416 int r;
417 bool formatted = false;
418
419 r = __superblock_all_zeroes(cmd->bm, &formatted);
420 if (r)
421 return r;
422
423 if (!formatted)
424 return may_format_device ? __format_metadata(cmd) : -EPERM;
425
426 return __open_metadata(cmd);
427}
428
429static int __create_persistent_data_structures(struct dm_clone_metadata *cmd,
430 bool may_format_device)
431{
432 int r;
433
434 /* Create block manager */
435 cmd->bm = dm_block_manager_create(cmd->bdev,
436 DM_CLONE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
437 DM_CLONE_MAX_CONCURRENT_LOCKS);
438 if (IS_ERR(cmd->bm)) {
439 DMERR("Failed to create block manager");
440 return PTR_ERR(cmd->bm);
441 }
442
443 r = __open_or_format_metadata(cmd, may_format_device);
444 if (r)
445 dm_block_manager_destroy(cmd->bm);
446
447 return r;
448}
449
450static void __destroy_persistent_data_structures(struct dm_clone_metadata *cmd)
451{
452 dm_sm_destroy(cmd->sm);
453 dm_tm_destroy(cmd->tm);
454 dm_block_manager_destroy(cmd->bm);
455}
456
457/*---------------------------------------------------------------------------*/
458
459static size_t bitmap_size(unsigned long nr_bits)
460{
461 return BITS_TO_LONGS(nr_bits) * sizeof(long);
462}
463
464static int dirty_map_init(struct dm_clone_metadata *cmd)
465{
466 cmd->dmap[0].changed = 0;
467 cmd->dmap[0].dirty_words = kvzalloc(bitmap_size(cmd->nr_words), GFP_KERNEL);
468
469 if (!cmd->dmap[0].dirty_words) {
470 DMERR("Failed to allocate dirty bitmap");
471 return -ENOMEM;
472 }
473
474 cmd->dmap[1].changed = 0;
475 cmd->dmap[1].dirty_words = kvzalloc(bitmap_size(cmd->nr_words), GFP_KERNEL);
476
477 if (!cmd->dmap[1].dirty_words) {
478 DMERR("Failed to allocate dirty bitmap");
479 kvfree(cmd->dmap[0].dirty_words);
480 return -ENOMEM;
481 }
482
483 cmd->current_dmap = &cmd->dmap[0];
484
485 return 0;
486}
487
488static void dirty_map_exit(struct dm_clone_metadata *cmd)
489{
490 kvfree(cmd->dmap[0].dirty_words);
491 kvfree(cmd->dmap[1].dirty_words);
492}
493
494static int __load_bitset_in_core(struct dm_clone_metadata *cmd)
495{
496 int r;
497 unsigned long i;
498 struct dm_bitset_cursor c;
499
500 /* Flush bitset cache */
501 r = dm_bitset_flush(&cmd->bitset_info, cmd->bitset_root, &cmd->bitset_root);
502 if (r)
503 return r;
504
505 r = dm_bitset_cursor_begin(&cmd->bitset_info, cmd->bitset_root, cmd->nr_regions, &c);
506 if (r)
507 return r;
508
509 for (i = 0; ; i++) {
510 if (dm_bitset_cursor_get_value(&c))
511 __set_bit(i, cmd->region_map);
512 else
513 __clear_bit(i, cmd->region_map);
514
515 if (i >= (cmd->nr_regions - 1))
516 break;
517
518 r = dm_bitset_cursor_next(&c);
519
520 if (r)
521 break;
522 }
523
524 dm_bitset_cursor_end(&c);
525
526 return r;
527}
528
529struct dm_clone_metadata *dm_clone_metadata_open(struct block_device *bdev,
530 sector_t target_size,
531 sector_t region_size)
532{
533 int r;
534 struct dm_clone_metadata *cmd;
535
536 cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
537 if (!cmd) {
538 DMERR("Failed to allocate memory for dm-clone metadata");
539 return ERR_PTR(-ENOMEM);
540 }
541
542 cmd->bdev = bdev;
543 cmd->target_size = target_size;
544 cmd->region_size = region_size;
545 cmd->nr_regions = dm_sector_div_up(cmd->target_size, cmd->region_size);
546 cmd->nr_words = BITS_TO_LONGS(cmd->nr_regions);
547
548 init_rwsem(&cmd->lock);
549 spin_lock_init(&cmd->bitmap_lock);
550 cmd->read_only = 0;
551 cmd->fail_io = false;
552 cmd->hydration_done = false;
553
554 cmd->region_map = kvmalloc(bitmap_size(cmd->nr_regions), GFP_KERNEL);
555 if (!cmd->region_map) {
556 DMERR("Failed to allocate memory for region bitmap");
557 r = -ENOMEM;
558 goto out_with_md;
559 }
560
561 r = __create_persistent_data_structures(cmd, true);
562 if (r)
563 goto out_with_region_map;
564
565 r = __load_bitset_in_core(cmd);
566 if (r) {
567 DMERR("Failed to load on-disk region map");
568 goto out_with_pds;
569 }
570
571 r = dirty_map_init(cmd);
572 if (r)
573 goto out_with_pds;
574
575 if (bitmap_full(cmd->region_map, cmd->nr_regions))
576 cmd->hydration_done = true;
577
578 return cmd;
579
580out_with_pds:
581 __destroy_persistent_data_structures(cmd);
582
583out_with_region_map:
584 kvfree(cmd->region_map);
585
586out_with_md:
587 kfree(cmd);
588
589 return ERR_PTR(r);
590}
591
592void dm_clone_metadata_close(struct dm_clone_metadata *cmd)
593{
594 if (!cmd->fail_io)
595 __destroy_persistent_data_structures(cmd);
596
597 dirty_map_exit(cmd);
598 kvfree(cmd->region_map);
599 kfree(cmd);
600}
601
602bool dm_clone_is_hydration_done(struct dm_clone_metadata *cmd)
603{
604 return cmd->hydration_done;
605}
606
607bool dm_clone_is_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr)
608{
609 return dm_clone_is_hydration_done(cmd) || test_bit(region_nr, cmd->region_map);
610}
611
612bool dm_clone_is_range_hydrated(struct dm_clone_metadata *cmd,
613 unsigned long start, unsigned long nr_regions)
614{
615 unsigned long bit;
616
617 if (dm_clone_is_hydration_done(cmd))
618 return true;
619
620 bit = find_next_zero_bit(cmd->region_map, cmd->nr_regions, start);
621
622 return (bit >= (start + nr_regions));
623}
624
625unsigned long dm_clone_nr_of_hydrated_regions(struct dm_clone_metadata *cmd)
626{
627 return bitmap_weight(cmd->region_map, cmd->nr_regions);
628}
629
630unsigned long dm_clone_find_next_unhydrated_region(struct dm_clone_metadata *cmd,
631 unsigned long start)
632{
633 return find_next_zero_bit(cmd->region_map, cmd->nr_regions, start);
634}
635
636static int __update_metadata_word(struct dm_clone_metadata *cmd, unsigned long word)
637{
638 int r;
639 unsigned long index = word * BITS_PER_LONG;
640 unsigned long max_index = min(cmd->nr_regions, (word + 1) * BITS_PER_LONG);
641
642 while (index < max_index) {
643 if (test_bit(index, cmd->region_map)) {
644 r = dm_bitset_set_bit(&cmd->bitset_info, cmd->bitset_root,
645 index, &cmd->bitset_root);
646
647 if (r) {
648 DMERR("dm_bitset_set_bit failed");
649 return r;
650 }
651 }
652 index++;
653 }
654
655 return 0;
656}
657
658static int __metadata_commit(struct dm_clone_metadata *cmd)
659{
660 int r;
661 struct dm_block *sblock;
662 struct superblock_disk *sb;
663
664 /* Flush bitset cache */
665 r = dm_bitset_flush(&cmd->bitset_info, cmd->bitset_root, &cmd->bitset_root);
666 if (r) {
667 DMERR("dm_bitset_flush failed");
668 return r;
669 }
670
671 /* Flush to disk all blocks, except the superblock */
672 r = dm_tm_pre_commit(cmd->tm);
673 if (r) {
674 DMERR("dm_tm_pre_commit failed");
675 return r;
676 }
677
678 /* Save the space map root in cmd->metadata_space_map_root */
679 r = __copy_sm_root(cmd);
680 if (r) {
681 DMERR("__copy_sm_root failed");
682 return r;
683 }
684
685 /* Lock the superblock */
686 r = superblock_write_lock_zero(cmd, &sblock);
687 if (r) {
688 DMERR("Failed to write_lock superblock");
689 return r;
690 }
691
692 /* Save the metadata in superblock */
693 sb = dm_block_data(sblock);
694 __prepare_superblock(cmd, sb);
695
696 /* Unlock superblock and commit it to disk */
697 r = dm_tm_commit(cmd->tm, sblock);
698 if (r) {
699 DMERR("Failed to commit superblock");
700 return r;
701 }
702
703 /*
704 * FIXME: Find a more efficient way to check if the hydration is done.
705 */
706 if (bitmap_full(cmd->region_map, cmd->nr_regions))
707 cmd->hydration_done = true;
708
709 return 0;
710}
711
712static int __flush_dmap(struct dm_clone_metadata *cmd, struct dirty_map *dmap)
713{
714 int r;
715 unsigned long word, flags;
716
717 word = 0;
718 do {
719 word = find_next_bit(dmap->dirty_words, cmd->nr_words, word);
720
721 if (word == cmd->nr_words)
722 break;
723
724 r = __update_metadata_word(cmd, word);
725
726 if (r)
727 return r;
728
729 __clear_bit(word, dmap->dirty_words);
730 word++;
731 } while (word < cmd->nr_words);
732
733 r = __metadata_commit(cmd);
734
735 if (r)
736 return r;
737
738 /* Update the changed flag */
739 spin_lock_irqsave(&cmd->bitmap_lock, flags);
740 dmap->changed = 0;
741 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
742
743 return 0;
744}
745
746int dm_clone_metadata_commit(struct dm_clone_metadata *cmd)
747{
748 int r = -EPERM;
749 unsigned long flags;
750 struct dirty_map *dmap, *next_dmap;
751
752 down_write(&cmd->lock);
753
754 if (cmd->fail_io || dm_bm_is_read_only(cmd->bm))
755 goto out;
756
757 /* Get current dirty bitmap */
758 dmap = cmd->current_dmap;
759
760 /* Get next dirty bitmap */
761 next_dmap = (dmap == &cmd->dmap[0]) ? &cmd->dmap[1] : &cmd->dmap[0];
762
763 /*
764 * The last commit failed, so we don't have a clean dirty-bitmap to
765 * use.
766 */
767 if (WARN_ON(next_dmap->changed)) {
768 r = -EINVAL;
769 goto out;
770 }
771
772 /* Swap dirty bitmaps */
773 spin_lock_irqsave(&cmd->bitmap_lock, flags);
774 cmd->current_dmap = next_dmap;
775 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
776
777 /*
778 * No one is accessing the old dirty bitmap anymore, so we can flush
779 * it.
780 */
781 r = __flush_dmap(cmd, dmap);
782out:
783 up_write(&cmd->lock);
784
785 return r;
786}
787
788int dm_clone_set_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr)
789{
790 int r = 0;
791 struct dirty_map *dmap;
792 unsigned long word, flags;
793
794 word = region_nr / BITS_PER_LONG;
795
796 spin_lock_irqsave(&cmd->bitmap_lock, flags);
797
798 if (cmd->read_only) {
799 r = -EPERM;
800 goto out;
801 }
802
803 dmap = cmd->current_dmap;
804
805 __set_bit(word, dmap->dirty_words);
806 __set_bit(region_nr, cmd->region_map);
807 dmap->changed = 1;
808
809out:
810 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
811
812 return r;
813}
814
815int dm_clone_cond_set_range(struct dm_clone_metadata *cmd, unsigned long start,
816 unsigned long nr_regions)
817{
818 int r = 0;
819 struct dirty_map *dmap;
820 unsigned long word, region_nr, flags;
821
822 spin_lock_irqsave(&cmd->bitmap_lock, flags);
823
824 if (cmd->read_only) {
825 r = -EPERM;
826 goto out;
827 }
828
829 dmap = cmd->current_dmap;
830 for (region_nr = start; region_nr < (start + nr_regions); region_nr++) {
831 if (!test_bit(region_nr, cmd->region_map)) {
832 word = region_nr / BITS_PER_LONG;
833 __set_bit(word, dmap->dirty_words);
834 __set_bit(region_nr, cmd->region_map);
835 dmap->changed = 1;
836 }
837 }
838out:
839 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
840
841 return r;
842}
843
844/*
845 * WARNING: This must not be called concurrently with either
846 * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), as it changes
847 * cmd->region_map without taking the cmd->bitmap_lock spinlock. The only
848 * exception is after setting the metadata to read-only mode, using
849 * dm_clone_metadata_set_read_only().
850 *
851 * We don't take the spinlock because __load_bitset_in_core() does I/O, so it
852 * may block.
853 */
854int dm_clone_reload_in_core_bitset(struct dm_clone_metadata *cmd)
855{
856 int r = -EINVAL;
857
858 down_write(&cmd->lock);
859
860 if (cmd->fail_io)
861 goto out;
862
863 r = __load_bitset_in_core(cmd);
864out:
865 up_write(&cmd->lock);
866
867 return r;
868}
869
870bool dm_clone_changed_this_transaction(struct dm_clone_metadata *cmd)
871{
872 bool r;
873 unsigned long flags;
874
875 spin_lock_irqsave(&cmd->bitmap_lock, flags);
876 r = cmd->dmap[0].changed || cmd->dmap[1].changed;
877 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
878
879 return r;
880}
881
882int dm_clone_metadata_abort(struct dm_clone_metadata *cmd)
883{
884 int r = -EPERM;
885
886 down_write(&cmd->lock);
887
888 if (cmd->fail_io || dm_bm_is_read_only(cmd->bm))
889 goto out;
890
891 __destroy_persistent_data_structures(cmd);
892
893 r = __create_persistent_data_structures(cmd, false);
894 if (r) {
895 /* If something went wrong we can neither write nor read the metadata */
896 cmd->fail_io = true;
897 }
898out:
899 up_write(&cmd->lock);
900
901 return r;
902}
903
904void dm_clone_metadata_set_read_only(struct dm_clone_metadata *cmd)
905{
906 unsigned long flags;
907
908 down_write(&cmd->lock);
909
910 spin_lock_irqsave(&cmd->bitmap_lock, flags);
911 cmd->read_only = 1;
912 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
913
914 if (!cmd->fail_io)
915 dm_bm_set_read_only(cmd->bm);
916
917 up_write(&cmd->lock);
918}
919
920void dm_clone_metadata_set_read_write(struct dm_clone_metadata *cmd)
921{
922 unsigned long flags;
923
924 down_write(&cmd->lock);
925
926 spin_lock_irqsave(&cmd->bitmap_lock, flags);
927 cmd->read_only = 0;
928 spin_unlock_irqrestore(&cmd->bitmap_lock, flags);
929
930 if (!cmd->fail_io)
931 dm_bm_set_read_write(cmd->bm);
932
933 up_write(&cmd->lock);
934}
935
936int dm_clone_get_free_metadata_block_count(struct dm_clone_metadata *cmd,
937 dm_block_t *result)
938{
939 int r = -EINVAL;
940
941 down_read(&cmd->lock);
942
943 if (!cmd->fail_io)
944 r = dm_sm_get_nr_free(cmd->sm, result);
945
946 up_read(&cmd->lock);
947
948 return r;
949}
950
951int dm_clone_get_metadata_dev_size(struct dm_clone_metadata *cmd,
952 dm_block_t *result)
953{
954 int r = -EINVAL;
955
956 down_read(&cmd->lock);
957
958 if (!cmd->fail_io)
959 r = dm_sm_get_nr_blocks(cmd->sm, result);
960
961 up_read(&cmd->lock);
962
963 return r;
964}