1// SPDX-License-Identifier: GPL-2.0-only
   2#include "dm.h"
   3#include "persistent-data/dm-transaction-manager.h"
   4#include "persistent-data/dm-bitset.h"
   5#include "persistent-data/dm-space-map.h"
   6
   7#include <linux/dm-io.h>
   8#include <linux/dm-kcopyd.h>
   9#include <linux/init.h>
  10#include <linux/mempool.h>
  11#include <linux/module.h>
  12#include <linux/slab.h>
  13#include <linux/vmalloc.h>
  14
  15#define DM_MSG_PREFIX "era"
  16
  17#define SUPERBLOCK_LOCATION 0
  18#define SUPERBLOCK_MAGIC 2126579579
  19#define SUPERBLOCK_CSUM_XOR 146538381
  20#define MIN_ERA_VERSION 1
  21#define MAX_ERA_VERSION 1
  22#define INVALID_WRITESET_ROOT SUPERBLOCK_LOCATION
  23#define MIN_BLOCK_SIZE 8
  24
  25/*----------------------------------------------------------------
  26 * Writeset
  27 *--------------------------------------------------------------*/
  28struct writeset_metadata {
  29	uint32_t nr_bits;
  30	dm_block_t root;
  31};
  32
  33struct writeset {
  34	struct writeset_metadata md;
  35
  36	/*
  37	 * An in core copy of the bits to save constantly doing look ups on
  38	 * disk.
  39	 */
  40	unsigned long *bits;
  41};
  42
  43/*
  44 * This does not free off the on disk bitset as this will normally be done
  45 * after digesting into the era array.
  46 */
  47static void writeset_free(struct writeset *ws)
  48{
  49	vfree(ws->bits);
  50	ws->bits = NULL;
  51}
  52
  53static int setup_on_disk_bitset(struct dm_disk_bitset *info,
  54				unsigned nr_bits, dm_block_t *root)
  55{
  56	int r;
  57
  58	r = dm_bitset_empty(info, root);
  59	if (r)
  60		return r;
  61
  62	return dm_bitset_resize(info, *root, 0, nr_bits, false, root);
  63}
  64
  65static size_t bitset_size(unsigned nr_bits)
  66{
  67	return sizeof(unsigned long) * dm_div_up(nr_bits, BITS_PER_LONG);
  68}
  69
  70/*
  71 * Allocates memory for the in core bitset.
  72 */
  73static int writeset_alloc(struct writeset *ws, dm_block_t nr_blocks)
  74{
 
 
  75	ws->bits = vzalloc(bitset_size(nr_blocks));
  76	if (!ws->bits) {
  77		DMERR("%s: couldn't allocate in memory bitset", __func__);
  78		return -ENOMEM;
  79	}
  80
  81	return 0;
  82}
  83
  84/*
  85 * Wipes the in-core bitset, and creates a new on disk bitset.
  86 */
  87static int writeset_init(struct dm_disk_bitset *info, struct writeset *ws,
  88			 dm_block_t nr_blocks)
  89{
  90	int r;
  91
  92	memset(ws->bits, 0, bitset_size(nr_blocks));
  93
  94	ws->md.nr_bits = nr_blocks;
  95	r = setup_on_disk_bitset(info, ws->md.nr_bits, &ws->md.root);
  96	if (r) {
  97		DMERR("%s: setup_on_disk_bitset failed", __func__);
  98		return r;
  99	}
 100
 101	return 0;
 102}
 103
 104static bool writeset_marked(struct writeset *ws, dm_block_t block)
 105{
 106	return test_bit(block, ws->bits);
 107}
 108
 109static int writeset_marked_on_disk(struct dm_disk_bitset *info,
 110				   struct writeset_metadata *m, dm_block_t block,
 111				   bool *result)
 112{
 113	dm_block_t old = m->root;
 114
 115	/*
 116	 * The bitset was flushed when it was archived, so we know there'll
 117	 * be no change to the root.
 118	 */
 119	int r = dm_bitset_test_bit(info, m->root, block, &m->root, result);
 120	if (r) {
 121		DMERR("%s: dm_bitset_test_bit failed", __func__);
 122		return r;
 123	}
 124
 125	BUG_ON(m->root != old);
 126
 127	return r;
 128}
 129
 130/*
 131 * Returns < 0 on error, 0 if the bit wasn't previously set, 1 if it was.
 132 */
 133static int writeset_test_and_set(struct dm_disk_bitset *info,
 134				 struct writeset *ws, uint32_t block)
 135{
 136	int r;
 137
 138	if (!test_bit(block, ws->bits)) {
 139		r = dm_bitset_set_bit(info, ws->md.root, block, &ws->md.root);
 140		if (r) {
 141			/* FIXME: fail mode */
 142			return r;
 143		}
 144
 145		return 0;
 146	}
 147
 148	return 1;
 149}
 150
 151/*----------------------------------------------------------------
 152 * On disk metadata layout
 153 *--------------------------------------------------------------*/
 154#define SPACE_MAP_ROOT_SIZE 128
 155#define UUID_LEN 16
 156
 157struct writeset_disk {
 158	__le32 nr_bits;
 159	__le64 root;
 160} __packed;
 161
 162struct superblock_disk {
 163	__le32 csum;
 164	__le32 flags;
 165	__le64 blocknr;
 166
 167	__u8 uuid[UUID_LEN];
 168	__le64 magic;
 169	__le32 version;
 170
 171	__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 172
 173	__le32 data_block_size;
 174	__le32 metadata_block_size;
 175	__le32 nr_blocks;
 176
 177	__le32 current_era;
 178	struct writeset_disk current_writeset;
 179
 180	/*
 181	 * Only these two fields are valid within the metadata snapshot.
 182	 */
 183	__le64 writeset_tree_root;
 184	__le64 era_array_root;
 185
 186	__le64 metadata_snap;
 187} __packed;
 188
 189/*----------------------------------------------------------------
 190 * Superblock validation
 191 *--------------------------------------------------------------*/
 192static void sb_prepare_for_write(struct dm_block_validator *v,
 193				 struct dm_block *b,
 194				 size_t sb_block_size)
 195{
 196	struct superblock_disk *disk = dm_block_data(b);
 197
 198	disk->blocknr = cpu_to_le64(dm_block_location(b));
 199	disk->csum = cpu_to_le32(dm_bm_checksum(&disk->flags,
 200						sb_block_size - sizeof(__le32),
 201						SUPERBLOCK_CSUM_XOR));
 202}
 203
 204static int check_metadata_version(struct superblock_disk *disk)
 205{
 206	uint32_t metadata_version = le32_to_cpu(disk->version);
 207	if (metadata_version < MIN_ERA_VERSION || metadata_version > MAX_ERA_VERSION) {
 208		DMERR("Era metadata version %u found, but only versions between %u and %u supported.",
 209		      metadata_version, MIN_ERA_VERSION, MAX_ERA_VERSION);
 210		return -EINVAL;
 211	}
 212
 213	return 0;
 214}
 215
 216static int sb_check(struct dm_block_validator *v,
 217		    struct dm_block *b,
 218		    size_t sb_block_size)
 219{
 220	struct superblock_disk *disk = dm_block_data(b);
 221	__le32 csum_le;
 222
 223	if (dm_block_location(b) != le64_to_cpu(disk->blocknr)) {
 224		DMERR("sb_check failed: blocknr %llu: wanted %llu",
 225		      le64_to_cpu(disk->blocknr),
 226		      (unsigned long long)dm_block_location(b));
 227		return -ENOTBLK;
 228	}
 229
 230	if (le64_to_cpu(disk->magic) != SUPERBLOCK_MAGIC) {
 231		DMERR("sb_check failed: magic %llu: wanted %llu",
 232		      le64_to_cpu(disk->magic),
 233		      (unsigned long long) SUPERBLOCK_MAGIC);
 234		return -EILSEQ;
 235	}
 236
 237	csum_le = cpu_to_le32(dm_bm_checksum(&disk->flags,
 238					     sb_block_size - sizeof(__le32),
 239					     SUPERBLOCK_CSUM_XOR));
 240	if (csum_le != disk->csum) {
 241		DMERR("sb_check failed: csum %u: wanted %u",
 242		      le32_to_cpu(csum_le), le32_to_cpu(disk->csum));
 243		return -EILSEQ;
 244	}
 245
 246	return check_metadata_version(disk);
 247}
 248
 249static struct dm_block_validator sb_validator = {
 250	.name = "superblock",
 251	.prepare_for_write = sb_prepare_for_write,
 252	.check = sb_check
 253};
 254
 255/*----------------------------------------------------------------
 256 * Low level metadata handling
 257 *--------------------------------------------------------------*/
 258#define DM_ERA_METADATA_BLOCK_SIZE 4096
 259#define ERA_MAX_CONCURRENT_LOCKS 5
 260
 261struct era_metadata {
 262	struct block_device *bdev;
 263	struct dm_block_manager *bm;
 264	struct dm_space_map *sm;
 265	struct dm_transaction_manager *tm;
 266
 267	dm_block_t block_size;
 268	uint32_t nr_blocks;
 269
 270	uint32_t current_era;
 271
 272	/*
 273	 * We preallocate 2 writesets.  When an era rolls over we
 274	 * switch between them. This means the allocation is done at
 275	 * preresume time, rather than on the io path.
 276	 */
 277	struct writeset writesets[2];
 278	struct writeset *current_writeset;
 279
 280	dm_block_t writeset_tree_root;
 281	dm_block_t era_array_root;
 282
 283	struct dm_disk_bitset bitset_info;
 284	struct dm_btree_info writeset_tree_info;
 285	struct dm_array_info era_array_info;
 286
 287	dm_block_t metadata_snap;
 288
 289	/*
 290	 * A flag that is set whenever a writeset has been archived.
 291	 */
 292	bool archived_writesets;
 293
 294	/*
 295	 * Reading the space map root can fail, so we read it into this
 296	 * buffer before the superblock is locked and updated.
 297	 */
 298	__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 299};
 300
 301static int superblock_read_lock(struct era_metadata *md,
 302				struct dm_block **sblock)
 303{
 304	return dm_bm_read_lock(md->bm, SUPERBLOCK_LOCATION,
 305			       &sb_validator, sblock);
 306}
 307
 308static int superblock_lock_zero(struct era_metadata *md,
 309				struct dm_block **sblock)
 310{
 311	return dm_bm_write_lock_zero(md->bm, SUPERBLOCK_LOCATION,
 312				     &sb_validator, sblock);
 313}
 314
 315static int superblock_lock(struct era_metadata *md,
 316			   struct dm_block **sblock)
 317{
 318	return dm_bm_write_lock(md->bm, SUPERBLOCK_LOCATION,
 319				&sb_validator, sblock);
 320}
 321
 322/* FIXME: duplication with cache and thin */
 323static int superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 324{
 325	int r;
 326	unsigned i;
 327	struct dm_block *b;
 328	__le64 *data_le, zero = cpu_to_le64(0);
 329	unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64);
 330
 331	/*
 332	 * We can't use a validator here - it may be all zeroes.
 333	 */
 334	r = dm_bm_read_lock(bm, SUPERBLOCK_LOCATION, NULL, &b);
 335	if (r)
 336		return r;
 337
 338	data_le = dm_block_data(b);
 339	*result = true;
 340	for (i = 0; i < sb_block_size; i++) {
 341		if (data_le[i] != zero) {
 342			*result = false;
 343			break;
 344		}
 345	}
 346
 347	dm_bm_unlock(b);
 348
 349	return 0;
 350}
 351
 352/*----------------------------------------------------------------*/
 353
 354static void ws_pack(const struct writeset_metadata *core, struct writeset_disk *disk)
 355{
 356	disk->nr_bits = cpu_to_le32(core->nr_bits);
 357	disk->root = cpu_to_le64(core->root);
 358}
 359
 360static void ws_unpack(const struct writeset_disk *disk, struct writeset_metadata *core)
 361{
 362	core->nr_bits = le32_to_cpu(disk->nr_bits);
 363	core->root = le64_to_cpu(disk->root);
 364}
 365
 366static void ws_inc(void *context, const void *value, unsigned count)
 367{
 368	struct era_metadata *md = context;
 369	struct writeset_disk ws_d;
 370	dm_block_t b;
 371	unsigned i;
 372
 373	for (i = 0; i < count; i++) {
 374		memcpy(&ws_d, value + (i * sizeof(ws_d)), sizeof(ws_d));
 375		b = le64_to_cpu(ws_d.root);
 376		dm_tm_inc(md->tm, b);
 377	}
 378}
 379
 380static void ws_dec(void *context, const void *value, unsigned count)
 381{
 382	struct era_metadata *md = context;
 383	struct writeset_disk ws_d;
 384	dm_block_t b;
 385	unsigned i;
 386
 387	for (i = 0; i < count; i++) {
 388		memcpy(&ws_d, value + (i * sizeof(ws_d)), sizeof(ws_d));
 389		b = le64_to_cpu(ws_d.root);
 390		dm_bitset_del(&md->bitset_info, b);
 391	}
 392}
 393
 394static int ws_eq(void *context, const void *value1, const void *value2)
 395{
 396	return !memcmp(value1, value2, sizeof(struct writeset_disk));
 397}
 398
 399/*----------------------------------------------------------------*/
 400
 401static void setup_writeset_tree_info(struct era_metadata *md)
 402{
 403	struct dm_btree_value_type *vt = &md->writeset_tree_info.value_type;
 404	md->writeset_tree_info.tm = md->tm;
 405	md->writeset_tree_info.levels = 1;
 406	vt->context = md;
 407	vt->size = sizeof(struct writeset_disk);
 408	vt->inc = ws_inc;
 409	vt->dec = ws_dec;
 410	vt->equal = ws_eq;
 411}
 412
 413static void setup_era_array_info(struct era_metadata *md)
 414
 415{
 416	struct dm_btree_value_type vt;
 417	vt.context = NULL;
 418	vt.size = sizeof(__le32);
 419	vt.inc = NULL;
 420	vt.dec = NULL;
 421	vt.equal = NULL;
 422
 423	dm_array_info_init(&md->era_array_info, md->tm, &vt);
 424}
 425
 426static void setup_infos(struct era_metadata *md)
 427{
 428	dm_disk_bitset_init(md->tm, &md->bitset_info);
 429	setup_writeset_tree_info(md);
 430	setup_era_array_info(md);
 431}
 432
 433/*----------------------------------------------------------------*/
 434
 435static int create_fresh_metadata(struct era_metadata *md)
 436{
 437	int r;
 438
 439	r = dm_tm_create_with_sm(md->bm, SUPERBLOCK_LOCATION,
 440				 &md->tm, &md->sm);
 441	if (r < 0) {
 442		DMERR("dm_tm_create_with_sm failed");
 443		return r;
 444	}
 445
 446	setup_infos(md);
 447
 448	r = dm_btree_empty(&md->writeset_tree_info, &md->writeset_tree_root);
 449	if (r) {
 450		DMERR("couldn't create new writeset tree");
 451		goto bad;
 452	}
 453
 454	r = dm_array_empty(&md->era_array_info, &md->era_array_root);
 455	if (r) {
 456		DMERR("couldn't create era array");
 457		goto bad;
 458	}
 459
 460	return 0;
 461
 462bad:
 463	dm_sm_destroy(md->sm);
 464	dm_tm_destroy(md->tm);
 465
 466	return r;
 467}
 468
 469static int save_sm_root(struct era_metadata *md)
 470{
 471	int r;
 472	size_t metadata_len;
 473
 474	r = dm_sm_root_size(md->sm, &metadata_len);
 475	if (r < 0)
 476		return r;
 477
 478	return dm_sm_copy_root(md->sm, &md->metadata_space_map_root,
 479			       metadata_len);
 480}
 481
 482static void copy_sm_root(struct era_metadata *md, struct superblock_disk *disk)
 483{
 484	memcpy(&disk->metadata_space_map_root,
 485	       &md->metadata_space_map_root,
 486	       sizeof(md->metadata_space_map_root));
 487}
 488
 489/*
 490 * Writes a superblock, including the static fields that don't get updated
 491 * with every commit (possible optimisation here).  'md' should be fully
 492 * constructed when this is called.
 493 */
 494static void prepare_superblock(struct era_metadata *md, struct superblock_disk *disk)
 495{
 496	disk->magic = cpu_to_le64(SUPERBLOCK_MAGIC);
 497	disk->flags = cpu_to_le32(0ul);
 498
 499	/* FIXME: can't keep blanking the uuid (uuid is currently unused though) */
 500	memset(disk->uuid, 0, sizeof(disk->uuid));
 501	disk->version = cpu_to_le32(MAX_ERA_VERSION);
 502
 503	copy_sm_root(md, disk);
 504
 505	disk->data_block_size = cpu_to_le32(md->block_size);
 506	disk->metadata_block_size = cpu_to_le32(DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
 507	disk->nr_blocks = cpu_to_le32(md->nr_blocks);
 508	disk->current_era = cpu_to_le32(md->current_era);
 509
 510	ws_pack(&md->current_writeset->md, &disk->current_writeset);
 511	disk->writeset_tree_root = cpu_to_le64(md->writeset_tree_root);
 512	disk->era_array_root = cpu_to_le64(md->era_array_root);
 513	disk->metadata_snap = cpu_to_le64(md->metadata_snap);
 514}
 515
 516static int write_superblock(struct era_metadata *md)
 517{
 518	int r;
 519	struct dm_block *sblock;
 520	struct superblock_disk *disk;
 521
 522	r = save_sm_root(md);
 523	if (r) {
 524		DMERR("%s: save_sm_root failed", __func__);
 525		return r;
 526	}
 527
 528	r = superblock_lock_zero(md, &sblock);
 529	if (r)
 530		return r;
 531
 532	disk = dm_block_data(sblock);
 533	prepare_superblock(md, disk);
 534
 535	return dm_tm_commit(md->tm, sblock);
 536}
 537
 538/*
 539 * Assumes block_size and the infos are set.
 540 */
 541static int format_metadata(struct era_metadata *md)
 542{
 543	int r;
 544
 545	r = create_fresh_metadata(md);
 546	if (r)
 547		return r;
 548
 549	r = write_superblock(md);
 550	if (r) {
 551		dm_sm_destroy(md->sm);
 552		dm_tm_destroy(md->tm);
 553		return r;
 554	}
 555
 556	return 0;
 557}
 558
 559static int open_metadata(struct era_metadata *md)
 560{
 561	int r;
 562	struct dm_block *sblock;
 563	struct superblock_disk *disk;
 564
 565	r = superblock_read_lock(md, &sblock);
 566	if (r) {
 567		DMERR("couldn't read_lock superblock");
 568		return r;
 569	}
 570
 571	disk = dm_block_data(sblock);
 572
 573	/* Verify the data block size hasn't changed */
 574	if (le32_to_cpu(disk->data_block_size) != md->block_size) {
 575		DMERR("changing the data block size (from %u to %llu) is not supported",
 576		      le32_to_cpu(disk->data_block_size), md->block_size);
 577		r = -EINVAL;
 578		goto bad;
 579	}
 580
 581	r = dm_tm_open_with_sm(md->bm, SUPERBLOCK_LOCATION,
 582			       disk->metadata_space_map_root,
 583			       sizeof(disk->metadata_space_map_root),
 584			       &md->tm, &md->sm);
 585	if (r) {
 586		DMERR("dm_tm_open_with_sm failed");
 587		goto bad;
 588	}
 589
 590	setup_infos(md);
 591
 
 592	md->nr_blocks = le32_to_cpu(disk->nr_blocks);
 593	md->current_era = le32_to_cpu(disk->current_era);
 594
 595	ws_unpack(&disk->current_writeset, &md->current_writeset->md);
 596	md->writeset_tree_root = le64_to_cpu(disk->writeset_tree_root);
 597	md->era_array_root = le64_to_cpu(disk->era_array_root);
 598	md->metadata_snap = le64_to_cpu(disk->metadata_snap);
 599	md->archived_writesets = true;
 600
 601	dm_bm_unlock(sblock);
 602
 603	return 0;
 604
 605bad:
 606	dm_bm_unlock(sblock);
 607	return r;
 608}
 609
 610static int open_or_format_metadata(struct era_metadata *md,
 611				   bool may_format)
 612{
 613	int r;
 614	bool unformatted = false;
 615
 616	r = superblock_all_zeroes(md->bm, &unformatted);
 617	if (r)
 618		return r;
 619
 620	if (unformatted)
 621		return may_format ? format_metadata(md) : -EPERM;
 622
 623	return open_metadata(md);
 624}
 625
 626static int create_persistent_data_objects(struct era_metadata *md,
 627					  bool may_format)
 628{
 629	int r;
 630
 631	md->bm = dm_block_manager_create(md->bdev, DM_ERA_METADATA_BLOCK_SIZE,
 632					 ERA_MAX_CONCURRENT_LOCKS);
 633	if (IS_ERR(md->bm)) {
 634		DMERR("could not create block manager");
 635		return PTR_ERR(md->bm);
 636	}
 637
 638	r = open_or_format_metadata(md, may_format);
 639	if (r)
 640		dm_block_manager_destroy(md->bm);
 641
 642	return r;
 643}
 644
 645static void destroy_persistent_data_objects(struct era_metadata *md)
 646{
 647	dm_sm_destroy(md->sm);
 648	dm_tm_destroy(md->tm);
 649	dm_block_manager_destroy(md->bm);
 650}
 651
 652/*
 653 * This waits until all era_map threads have picked up the new filter.
 654 */
 655static void swap_writeset(struct era_metadata *md, struct writeset *new_writeset)
 656{
 657	rcu_assign_pointer(md->current_writeset, new_writeset);
 658	synchronize_rcu();
 659}
 660
 661/*----------------------------------------------------------------
 662 * Writesets get 'digested' into the main era array.
 663 *
 664 * We're using a coroutine here so the worker thread can do the digestion,
 665 * thus avoiding synchronisation of the metadata.  Digesting a whole
 666 * writeset in one go would cause too much latency.
 667 *--------------------------------------------------------------*/
 668struct digest {
 669	uint32_t era;
 670	unsigned nr_bits, current_bit;
 671	struct writeset_metadata writeset;
 672	__le32 value;
 673	struct dm_disk_bitset info;
 674
 675	int (*step)(struct era_metadata *, struct digest *);
 676};
 677
 678static int metadata_digest_lookup_writeset(struct era_metadata *md,
 679					   struct digest *d);
 680
 681static int metadata_digest_remove_writeset(struct era_metadata *md,
 682					   struct digest *d)
 683{
 684	int r;
 685	uint64_t key = d->era;
 686
 687	r = dm_btree_remove(&md->writeset_tree_info, md->writeset_tree_root,
 688			    &key, &md->writeset_tree_root);
 689	if (r) {
 690		DMERR("%s: dm_btree_remove failed", __func__);
 691		return r;
 692	}
 693
 694	d->step = metadata_digest_lookup_writeset;
 695	return 0;
 696}
 697
 698#define INSERTS_PER_STEP 100
 699
 700static int metadata_digest_transcribe_writeset(struct era_metadata *md,
 701					       struct digest *d)
 702{
 703	int r;
 704	bool marked;
 705	unsigned b, e = min(d->current_bit + INSERTS_PER_STEP, d->nr_bits);
 706
 707	for (b = d->current_bit; b < e; b++) {
 708		r = writeset_marked_on_disk(&d->info, &d->writeset, b, &marked);
 709		if (r) {
 710			DMERR("%s: writeset_marked_on_disk failed", __func__);
 711			return r;
 712		}
 713
 714		if (!marked)
 715			continue;
 716
 717		__dm_bless_for_disk(&d->value);
 718		r = dm_array_set_value(&md->era_array_info, md->era_array_root,
 719				       b, &d->value, &md->era_array_root);
 720		if (r) {
 721			DMERR("%s: dm_array_set_value failed", __func__);
 722			return r;
 723		}
 724	}
 725
 726	if (b == d->nr_bits)
 727		d->step = metadata_digest_remove_writeset;
 728	else
 729		d->current_bit = b;
 730
 731	return 0;
 732}
 733
 734static int metadata_digest_lookup_writeset(struct era_metadata *md,
 735					   struct digest *d)
 736{
 737	int r;
 738	uint64_t key;
 739	struct writeset_disk disk;
 740
 741	r = dm_btree_find_lowest_key(&md->writeset_tree_info,
 742				     md->writeset_tree_root, &key);
 743	if (r < 0)
 744		return r;
 745
 746	d->era = key;
 747
 748	r = dm_btree_lookup(&md->writeset_tree_info,
 749			    md->writeset_tree_root, &key, &disk);
 750	if (r) {
 751		if (r == -ENODATA) {
 752			d->step = NULL;
 753			return 0;
 754		}
 755
 756		DMERR("%s: dm_btree_lookup failed", __func__);
 757		return r;
 758	}
 759
 760	ws_unpack(&disk, &d->writeset);
 761	d->value = cpu_to_le32(key);
 762
 763	/*
 764	 * We initialise another bitset info to avoid any caching side effects
 765	 * with the previous one.
 766	 */
 767	dm_disk_bitset_init(md->tm, &d->info);
 768
 769	d->nr_bits = min(d->writeset.nr_bits, md->nr_blocks);
 770	d->current_bit = 0;
 771	d->step = metadata_digest_transcribe_writeset;
 772
 773	return 0;
 774}
 775
 776static int metadata_digest_start(struct era_metadata *md, struct digest *d)
 777{
 778	if (d->step)
 779		return 0;
 780
 781	memset(d, 0, sizeof(*d));
 
 
 
 
 
 
 782	d->step = metadata_digest_lookup_writeset;
 783
 784	return 0;
 785}
 786
 787/*----------------------------------------------------------------
 788 * High level metadata interface.  Target methods should use these, and not
 789 * the lower level ones.
 790 *--------------------------------------------------------------*/
 791static struct era_metadata *metadata_open(struct block_device *bdev,
 792					  sector_t block_size,
 793					  bool may_format)
 794{
 795	int r;
 796	struct era_metadata *md = kzalloc(sizeof(*md), GFP_KERNEL);
 797
 798	if (!md)
 799		return NULL;
 800
 801	md->bdev = bdev;
 802	md->block_size = block_size;
 803
 804	md->writesets[0].md.root = INVALID_WRITESET_ROOT;
 805	md->writesets[1].md.root = INVALID_WRITESET_ROOT;
 806	md->current_writeset = &md->writesets[0];
 807
 808	r = create_persistent_data_objects(md, may_format);
 809	if (r) {
 810		kfree(md);
 811		return ERR_PTR(r);
 812	}
 813
 814	return md;
 815}
 816
 817static void metadata_close(struct era_metadata *md)
 818{
 819	writeset_free(&md->writesets[0]);
 820	writeset_free(&md->writesets[1]);
 821	destroy_persistent_data_objects(md);
 822	kfree(md);
 823}
 824
 825static bool valid_nr_blocks(dm_block_t n)
 826{
 827	/*
 828	 * dm_bitset restricts us to 2^32.  test_bit & co. restrict us
 829	 * further to 2^31 - 1
 830	 */
 831	return n < (1ull << 31);
 832}
 833
 834static int metadata_resize(struct era_metadata *md, void *arg)
 835{
 836	int r;
 837	dm_block_t *new_size = arg;
 838	__le32 value;
 839
 840	if (!valid_nr_blocks(*new_size)) {
 841		DMERR("Invalid number of origin blocks %llu",
 842		      (unsigned long long) *new_size);
 843		return -EINVAL;
 844	}
 845
 846	writeset_free(&md->writesets[0]);
 847	writeset_free(&md->writesets[1]);
 848
 849	r = writeset_alloc(&md->writesets[0], *new_size);
 850	if (r) {
 851		DMERR("%s: writeset_alloc failed for writeset 0", __func__);
 852		return r;
 853	}
 854
 855	r = writeset_alloc(&md->writesets[1], *new_size);
 856	if (r) {
 857		DMERR("%s: writeset_alloc failed for writeset 1", __func__);
 858		writeset_free(&md->writesets[0]);
 859		return r;
 860	}
 861
 862	value = cpu_to_le32(0u);
 863	__dm_bless_for_disk(&value);
 864	r = dm_array_resize(&md->era_array_info, md->era_array_root,
 865			    md->nr_blocks, *new_size,
 866			    &value, &md->era_array_root);
 867	if (r) {
 868		DMERR("%s: dm_array_resize failed", __func__);
 869		writeset_free(&md->writesets[0]);
 870		writeset_free(&md->writesets[1]);
 871		return r;
 872	}
 873
 874	md->nr_blocks = *new_size;
 875	return 0;
 876}
 877
 878static int metadata_era_archive(struct era_metadata *md)
 879{
 880	int r;
 881	uint64_t keys[1];
 882	struct writeset_disk value;
 883
 884	r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 885			    &md->current_writeset->md.root);
 886	if (r) {
 887		DMERR("%s: dm_bitset_flush failed", __func__);
 888		return r;
 889	}
 890
 891	ws_pack(&md->current_writeset->md, &value);
 
 892
 893	keys[0] = md->current_era;
 894	__dm_bless_for_disk(&value);
 895	r = dm_btree_insert(&md->writeset_tree_info, md->writeset_tree_root,
 896			    keys, &value, &md->writeset_tree_root);
 897	if (r) {
 898		DMERR("%s: couldn't insert writeset into btree", __func__);
 899		/* FIXME: fail mode */
 900		return r;
 901	}
 902
 903	md->current_writeset->md.root = INVALID_WRITESET_ROOT;
 904	md->archived_writesets = true;
 905
 906	return 0;
 907}
 908
 909static struct writeset *next_writeset(struct era_metadata *md)
 910{
 911	return (md->current_writeset == &md->writesets[0]) ?
 912		&md->writesets[1] : &md->writesets[0];
 913}
 914
 915static int metadata_new_era(struct era_metadata *md)
 916{
 917	int r;
 918	struct writeset *new_writeset = next_writeset(md);
 919
 920	r = writeset_init(&md->bitset_info, new_writeset, md->nr_blocks);
 921	if (r) {
 922		DMERR("%s: writeset_init failed", __func__);
 923		return r;
 924	}
 925
 926	swap_writeset(md, new_writeset);
 927	md->current_era++;
 928
 929	return 0;
 930}
 931
 932static int metadata_era_rollover(struct era_metadata *md)
 933{
 934	int r;
 935
 936	if (md->current_writeset->md.root != INVALID_WRITESET_ROOT) {
 937		r = metadata_era_archive(md);
 938		if (r) {
 939			DMERR("%s: metadata_archive_era failed", __func__);
 940			/* FIXME: fail mode? */
 941			return r;
 942		}
 943	}
 944
 945	r = metadata_new_era(md);
 946	if (r) {
 947		DMERR("%s: new era failed", __func__);
 948		/* FIXME: fail mode */
 949		return r;
 950	}
 951
 952	return 0;
 953}
 954
 955static bool metadata_current_marked(struct era_metadata *md, dm_block_t block)
 956{
 957	bool r;
 958	struct writeset *ws;
 959
 960	rcu_read_lock();
 961	ws = rcu_dereference(md->current_writeset);
 962	r = writeset_marked(ws, block);
 963	rcu_read_unlock();
 964
 965	return r;
 966}
 967
 968static int metadata_commit(struct era_metadata *md)
 969{
 970	int r;
 971	struct dm_block *sblock;
 972
 973	if (md->current_writeset->md.root != INVALID_WRITESET_ROOT) {
 974		r = dm_bitset_flush(&md->bitset_info, md->current_writeset->md.root,
 975				    &md->current_writeset->md.root);
 976		if (r) {
 977			DMERR("%s: bitset flush failed", __func__);
 978			return r;
 979		}
 980	}
 981
 982	r = dm_tm_pre_commit(md->tm);
 983	if (r) {
 984		DMERR("%s: pre commit failed", __func__);
 985		return r;
 986	}
 987
 988	r = save_sm_root(md);
 989	if (r) {
 990		DMERR("%s: save_sm_root failed", __func__);
 991		return r;
 992	}
 993
 994	r = superblock_lock(md, &sblock);
 995	if (r) {
 996		DMERR("%s: superblock lock failed", __func__);
 997		return r;
 998	}
 999
1000	prepare_superblock(md, dm_block_data(sblock));
1001
1002	return dm_tm_commit(md->tm, sblock);
1003}
1004
1005static int metadata_checkpoint(struct era_metadata *md)
1006{
1007	/*
1008	 * For now we just rollover, but later I want to put a check in to
1009	 * avoid this if the filter is still pretty fresh.
1010	 */
1011	return metadata_era_rollover(md);
1012}
1013
1014/*
1015 * Metadata snapshots allow userland to access era data.
1016 */
1017static int metadata_take_snap(struct era_metadata *md)
1018{
1019	int r, inc;
1020	struct dm_block *clone;
1021
1022	if (md->metadata_snap != SUPERBLOCK_LOCATION) {
1023		DMERR("%s: metadata snapshot already exists", __func__);
1024		return -EINVAL;
1025	}
1026
1027	r = metadata_era_rollover(md);
1028	if (r) {
1029		DMERR("%s: era rollover failed", __func__);
1030		return r;
1031	}
1032
1033	r = metadata_commit(md);
1034	if (r) {
1035		DMERR("%s: pre commit failed", __func__);
1036		return r;
1037	}
1038
1039	r = dm_sm_inc_block(md->sm, SUPERBLOCK_LOCATION);
1040	if (r) {
1041		DMERR("%s: couldn't increment superblock", __func__);
1042		return r;
1043	}
1044
1045	r = dm_tm_shadow_block(md->tm, SUPERBLOCK_LOCATION,
1046			       &sb_validator, &clone, &inc);
1047	if (r) {
1048		DMERR("%s: couldn't shadow superblock", __func__);
1049		dm_sm_dec_block(md->sm, SUPERBLOCK_LOCATION);
1050		return r;
1051	}
1052	BUG_ON(!inc);
1053
1054	r = dm_sm_inc_block(md->sm, md->writeset_tree_root);
1055	if (r) {
1056		DMERR("%s: couldn't inc writeset tree root", __func__);
1057		dm_tm_unlock(md->tm, clone);
1058		return r;
1059	}
1060
1061	r = dm_sm_inc_block(md->sm, md->era_array_root);
1062	if (r) {
1063		DMERR("%s: couldn't inc era tree root", __func__);
1064		dm_sm_dec_block(md->sm, md->writeset_tree_root);
1065		dm_tm_unlock(md->tm, clone);
1066		return r;
1067	}
1068
1069	md->metadata_snap = dm_block_location(clone);
1070
1071	dm_tm_unlock(md->tm, clone);
1072
1073	return 0;
1074}
1075
1076static int metadata_drop_snap(struct era_metadata *md)
1077{
1078	int r;
1079	dm_block_t location;
1080	struct dm_block *clone;
1081	struct superblock_disk *disk;
1082
1083	if (md->metadata_snap == SUPERBLOCK_LOCATION) {
1084		DMERR("%s: no snap to drop", __func__);
1085		return -EINVAL;
1086	}
1087
1088	r = dm_tm_read_lock(md->tm, md->metadata_snap, &sb_validator, &clone);
1089	if (r) {
1090		DMERR("%s: couldn't read lock superblock clone", __func__);
1091		return r;
1092	}
1093
1094	/*
1095	 * Whatever happens now we'll commit with no record of the metadata
1096	 * snap.
1097	 */
1098	md->metadata_snap = SUPERBLOCK_LOCATION;
1099
1100	disk = dm_block_data(clone);
1101	r = dm_btree_del(&md->writeset_tree_info,
1102			 le64_to_cpu(disk->writeset_tree_root));
1103	if (r) {
1104		DMERR("%s: error deleting writeset tree clone", __func__);
1105		dm_tm_unlock(md->tm, clone);
1106		return r;
1107	}
1108
1109	r = dm_array_del(&md->era_array_info, le64_to_cpu(disk->era_array_root));
1110	if (r) {
1111		DMERR("%s: error deleting era array clone", __func__);
1112		dm_tm_unlock(md->tm, clone);
1113		return r;
1114	}
1115
1116	location = dm_block_location(clone);
1117	dm_tm_unlock(md->tm, clone);
1118
1119	return dm_sm_dec_block(md->sm, location);
1120}
1121
1122struct metadata_stats {
1123	dm_block_t used;
1124	dm_block_t total;
1125	dm_block_t snap;
1126	uint32_t era;
1127};
1128
1129static int metadata_get_stats(struct era_metadata *md, void *ptr)
1130{
1131	int r;
1132	struct metadata_stats *s = ptr;
1133	dm_block_t nr_free, nr_total;
1134
1135	r = dm_sm_get_nr_free(md->sm, &nr_free);
1136	if (r) {
1137		DMERR("dm_sm_get_nr_free returned %d", r);
1138		return r;
1139	}
1140
1141	r = dm_sm_get_nr_blocks(md->sm, &nr_total);
1142	if (r) {
1143		DMERR("dm_pool_get_metadata_dev_size returned %d", r);
1144		return r;
1145	}
1146
1147	s->used = nr_total - nr_free;
1148	s->total = nr_total;
1149	s->snap = md->metadata_snap;
1150	s->era = md->current_era;
1151
1152	return 0;
1153}
1154
1155/*----------------------------------------------------------------*/
1156
1157struct era {
1158	struct dm_target *ti;
 
1159
1160	struct dm_dev *metadata_dev;
1161	struct dm_dev *origin_dev;
1162
1163	dm_block_t nr_blocks;
1164	uint32_t sectors_per_block;
1165	int sectors_per_block_shift;
1166	struct era_metadata *md;
1167
1168	struct workqueue_struct *wq;
1169	struct work_struct worker;
1170
1171	spinlock_t deferred_lock;
1172	struct bio_list deferred_bios;
1173
1174	spinlock_t rpc_lock;
1175	struct list_head rpc_calls;
1176
1177	struct digest digest;
1178	atomic_t suspended;
1179};
1180
1181struct rpc {
1182	struct list_head list;
1183
1184	int (*fn0)(struct era_metadata *);
1185	int (*fn1)(struct era_metadata *, void *);
1186	void *arg;
1187	int result;
1188
1189	struct completion complete;
1190};
1191
1192/*----------------------------------------------------------------
1193 * Remapping.
1194 *---------------------------------------------------------------*/
1195static bool block_size_is_power_of_two(struct era *era)
1196{
1197	return era->sectors_per_block_shift >= 0;
1198}
1199
1200static dm_block_t get_block(struct era *era, struct bio *bio)
1201{
1202	sector_t block_nr = bio->bi_iter.bi_sector;
1203
1204	if (!block_size_is_power_of_two(era))
1205		(void) sector_div(block_nr, era->sectors_per_block);
1206	else
1207		block_nr >>= era->sectors_per_block_shift;
1208
1209	return block_nr;
1210}
1211
1212static void remap_to_origin(struct era *era, struct bio *bio)
1213{
1214	bio_set_dev(bio, era->origin_dev->bdev);
1215}
1216
1217/*----------------------------------------------------------------
1218 * Worker thread
1219 *--------------------------------------------------------------*/
1220static void wake_worker(struct era *era)
1221{
1222	if (!atomic_read(&era->suspended))
1223		queue_work(era->wq, &era->worker);
1224}
1225
1226static void process_old_eras(struct era *era)
1227{
1228	int r;
1229
1230	if (!era->digest.step)
1231		return;
1232
1233	r = era->digest.step(era->md, &era->digest);
1234	if (r < 0) {
1235		DMERR("%s: digest step failed, stopping digestion", __func__);
1236		era->digest.step = NULL;
1237
1238	} else if (era->digest.step)
1239		wake_worker(era);
1240}
1241
1242static void process_deferred_bios(struct era *era)
1243{
1244	int r;
1245	struct bio_list deferred_bios, marked_bios;
1246	struct bio *bio;
1247	struct blk_plug plug;
1248	bool commit_needed = false;
1249	bool failed = false;
1250	struct writeset *ws = era->md->current_writeset;
1251
1252	bio_list_init(&deferred_bios);
1253	bio_list_init(&marked_bios);
1254
1255	spin_lock(&era->deferred_lock);
1256	bio_list_merge(&deferred_bios, &era->deferred_bios);
1257	bio_list_init(&era->deferred_bios);
1258	spin_unlock(&era->deferred_lock);
1259
1260	if (bio_list_empty(&deferred_bios))
1261		return;
1262
1263	while ((bio = bio_list_pop(&deferred_bios))) {
1264		r = writeset_test_and_set(&era->md->bitset_info, ws,
 
1265					  get_block(era, bio));
1266		if (r < 0) {
1267			/*
1268			 * This is bad news, we need to rollback.
1269			 * FIXME: finish.
1270			 */
1271			failed = true;
 
1272		} else if (r == 0)
1273			commit_needed = true;
1274
1275		bio_list_add(&marked_bios, bio);
1276	}
1277
1278	if (commit_needed) {
1279		r = metadata_commit(era->md);
1280		if (r)
1281			failed = true;
1282	}
1283
1284	if (failed)
1285		while ((bio = bio_list_pop(&marked_bios)))
1286			bio_io_error(bio);
1287	else {
1288		blk_start_plug(&plug);
1289		while ((bio = bio_list_pop(&marked_bios))) {
1290			/*
1291			 * Only update the in-core writeset if the on-disk one
1292			 * was updated too.
1293			 */
1294			if (commit_needed)
1295				set_bit(get_block(era, bio), ws->bits);
1296			submit_bio_noacct(bio);
1297		}
1298		blk_finish_plug(&plug);
1299	}
1300}
1301
1302static void process_rpc_calls(struct era *era)
1303{
1304	int r;
1305	bool need_commit = false;
1306	struct list_head calls;
1307	struct rpc *rpc, *tmp;
1308
1309	INIT_LIST_HEAD(&calls);
1310	spin_lock(&era->rpc_lock);
1311	list_splice_init(&era->rpc_calls, &calls);
1312	spin_unlock(&era->rpc_lock);
1313
1314	list_for_each_entry_safe(rpc, tmp, &calls, list) {
1315		rpc->result = rpc->fn0 ? rpc->fn0(era->md) : rpc->fn1(era->md, rpc->arg);
1316		need_commit = true;
1317	}
1318
1319	if (need_commit) {
1320		r = metadata_commit(era->md);
1321		if (r)
1322			list_for_each_entry_safe(rpc, tmp, &calls, list)
1323				rpc->result = r;
1324	}
1325
1326	list_for_each_entry_safe(rpc, tmp, &calls, list)
1327		complete(&rpc->complete);
1328}
1329
1330static void kick_off_digest(struct era *era)
1331{
1332	if (era->md->archived_writesets) {
1333		era->md->archived_writesets = false;
1334		metadata_digest_start(era->md, &era->digest);
1335	}
1336}
1337
1338static void do_work(struct work_struct *ws)
1339{
1340	struct era *era = container_of(ws, struct era, worker);
1341
1342	kick_off_digest(era);
1343	process_old_eras(era);
1344	process_deferred_bios(era);
1345	process_rpc_calls(era);
1346}
1347
1348static void defer_bio(struct era *era, struct bio *bio)
1349{
1350	spin_lock(&era->deferred_lock);
1351	bio_list_add(&era->deferred_bios, bio);
1352	spin_unlock(&era->deferred_lock);
1353
1354	wake_worker(era);
1355}
1356
1357/*
1358 * Make an rpc call to the worker to change the metadata.
1359 */
1360static int perform_rpc(struct era *era, struct rpc *rpc)
1361{
1362	rpc->result = 0;
1363	init_completion(&rpc->complete);
1364
1365	spin_lock(&era->rpc_lock);
1366	list_add(&rpc->list, &era->rpc_calls);
1367	spin_unlock(&era->rpc_lock);
1368
1369	wake_worker(era);
1370	wait_for_completion(&rpc->complete);
1371
1372	return rpc->result;
1373}
1374
1375static int in_worker0(struct era *era, int (*fn)(struct era_metadata *))
1376{
1377	struct rpc rpc;
1378	rpc.fn0 = fn;
1379	rpc.fn1 = NULL;
1380
1381	return perform_rpc(era, &rpc);
1382}
1383
1384static int in_worker1(struct era *era,
1385		      int (*fn)(struct era_metadata *, void *), void *arg)
1386{
1387	struct rpc rpc;
1388	rpc.fn0 = NULL;
1389	rpc.fn1 = fn;
1390	rpc.arg = arg;
1391
1392	return perform_rpc(era, &rpc);
1393}
1394
1395static void start_worker(struct era *era)
1396{
1397	atomic_set(&era->suspended, 0);
1398}
1399
1400static void stop_worker(struct era *era)
1401{
1402	atomic_set(&era->suspended, 1);
1403	drain_workqueue(era->wq);
1404}
1405
1406/*----------------------------------------------------------------
1407 * Target methods
1408 *--------------------------------------------------------------*/
 
 
 
 
 
 
 
 
 
 
 
 
1409static void era_destroy(struct era *era)
1410{
1411	if (era->md)
1412		metadata_close(era->md);
1413
1414	if (era->wq)
1415		destroy_workqueue(era->wq);
1416
1417	if (era->origin_dev)
1418		dm_put_device(era->ti, era->origin_dev);
1419
1420	if (era->metadata_dev)
1421		dm_put_device(era->ti, era->metadata_dev);
1422
1423	kfree(era);
1424}
1425
1426static dm_block_t calc_nr_blocks(struct era *era)
1427{
1428	return dm_sector_div_up(era->ti->len, era->sectors_per_block);
1429}
1430
1431static bool valid_block_size(dm_block_t block_size)
1432{
1433	bool greater_than_zero = block_size > 0;
1434	bool multiple_of_min_block_size = (block_size & (MIN_BLOCK_SIZE - 1)) == 0;
1435
1436	return greater_than_zero && multiple_of_min_block_size;
1437}
1438
1439/*
1440 * <metadata dev> <data dev> <data block size (sectors)>
1441 */
1442static int era_ctr(struct dm_target *ti, unsigned argc, char **argv)
1443{
1444	int r;
1445	char dummy;
1446	struct era *era;
1447	struct era_metadata *md;
1448
1449	if (argc != 3) {
1450		ti->error = "Invalid argument count";
1451		return -EINVAL;
1452	}
1453
1454	era = kzalloc(sizeof(*era), GFP_KERNEL);
1455	if (!era) {
1456		ti->error = "Error allocating era structure";
1457		return -ENOMEM;
1458	}
1459
1460	era->ti = ti;
1461
1462	r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &era->metadata_dev);
1463	if (r) {
1464		ti->error = "Error opening metadata device";
1465		era_destroy(era);
1466		return -EINVAL;
1467	}
1468
1469	r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &era->origin_dev);
1470	if (r) {
1471		ti->error = "Error opening data device";
1472		era_destroy(era);
1473		return -EINVAL;
1474	}
1475
1476	r = sscanf(argv[2], "%u%c", &era->sectors_per_block, &dummy);
1477	if (r != 1) {
1478		ti->error = "Error parsing block size";
1479		era_destroy(era);
1480		return -EINVAL;
1481	}
1482
1483	r = dm_set_target_max_io_len(ti, era->sectors_per_block);
1484	if (r) {
1485		ti->error = "could not set max io len";
1486		era_destroy(era);
1487		return -EINVAL;
1488	}
1489
1490	if (!valid_block_size(era->sectors_per_block)) {
1491		ti->error = "Invalid block size";
1492		era_destroy(era);
1493		return -EINVAL;
1494	}
1495	if (era->sectors_per_block & (era->sectors_per_block - 1))
1496		era->sectors_per_block_shift = -1;
1497	else
1498		era->sectors_per_block_shift = __ffs(era->sectors_per_block);
1499
1500	md = metadata_open(era->metadata_dev->bdev, era->sectors_per_block, true);
1501	if (IS_ERR(md)) {
1502		ti->error = "Error reading metadata";
1503		era_destroy(era);
1504		return PTR_ERR(md);
1505	}
1506	era->md = md;
1507
 
 
 
 
 
 
 
 
 
1508	era->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
1509	if (!era->wq) {
1510		ti->error = "could not create workqueue for metadata object";
1511		era_destroy(era);
1512		return -ENOMEM;
1513	}
1514	INIT_WORK(&era->worker, do_work);
1515
1516	spin_lock_init(&era->deferred_lock);
1517	bio_list_init(&era->deferred_bios);
1518
1519	spin_lock_init(&era->rpc_lock);
1520	INIT_LIST_HEAD(&era->rpc_calls);
1521
1522	ti->private = era;
1523	ti->num_flush_bios = 1;
1524	ti->flush_supported = true;
1525
1526	ti->num_discard_bios = 1;
 
 
1527
1528	return 0;
1529}
1530
1531static void era_dtr(struct dm_target *ti)
1532{
1533	era_destroy(ti->private);
1534}
1535
1536static int era_map(struct dm_target *ti, struct bio *bio)
1537{
1538	struct era *era = ti->private;
1539	dm_block_t block = get_block(era, bio);
1540
1541	/*
1542	 * All bios get remapped to the origin device.  We do this now, but
1543	 * it may not get issued until later.  Depending on whether the
1544	 * block is marked in this era.
1545	 */
1546	remap_to_origin(era, bio);
1547
1548	/*
1549	 * REQ_PREFLUSH bios carry no data, so we're not interested in them.
1550	 */
1551	if (!(bio->bi_opf & REQ_PREFLUSH) &&
1552	    (bio_data_dir(bio) == WRITE) &&
1553	    !metadata_current_marked(era->md, block)) {
1554		defer_bio(era, bio);
1555		return DM_MAPIO_SUBMITTED;
1556	}
1557
1558	return DM_MAPIO_REMAPPED;
1559}
1560
1561static void era_postsuspend(struct dm_target *ti)
1562{
1563	int r;
1564	struct era *era = ti->private;
1565
1566	r = in_worker0(era, metadata_era_archive);
1567	if (r) {
1568		DMERR("%s: couldn't archive current era", __func__);
1569		/* FIXME: fail mode */
1570	}
1571
1572	stop_worker(era);
1573
1574	r = metadata_commit(era->md);
1575	if (r) {
1576		DMERR("%s: metadata_commit failed", __func__);
1577		/* FIXME: fail mode */
1578	}
1579}
1580
1581static int era_preresume(struct dm_target *ti)
1582{
1583	int r;
1584	struct era *era = ti->private;
1585	dm_block_t new_size = calc_nr_blocks(era);
1586
1587	if (era->nr_blocks != new_size) {
1588		r = metadata_resize(era->md, &new_size);
1589		if (r) {
1590			DMERR("%s: metadata_resize failed", __func__);
1591			return r;
1592		}
1593
1594		r = metadata_commit(era->md);
1595		if (r) {
1596			DMERR("%s: metadata_commit failed", __func__);
1597			return r;
1598		}
1599
1600		era->nr_blocks = new_size;
1601	}
1602
1603	start_worker(era);
1604
1605	r = in_worker0(era, metadata_era_rollover);
1606	if (r) {
1607		DMERR("%s: metadata_era_rollover failed", __func__);
1608		return r;
1609	}
1610
1611	return 0;
1612}
1613
1614/*
1615 * Status format:
1616 *
1617 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
1618 * <current era> <held metadata root | '-'>
1619 */
1620static void era_status(struct dm_target *ti, status_type_t type,
1621		       unsigned status_flags, char *result, unsigned maxlen)
1622{
1623	int r;
1624	struct era *era = ti->private;
1625	ssize_t sz = 0;
1626	struct metadata_stats stats;
1627	char buf[BDEVNAME_SIZE];
1628
1629	switch (type) {
1630	case STATUSTYPE_INFO:
1631		r = in_worker1(era, metadata_get_stats, &stats);
1632		if (r)
1633			goto err;
1634
1635		DMEMIT("%u %llu/%llu %u",
1636		       (unsigned) (DM_ERA_METADATA_BLOCK_SIZE >> SECTOR_SHIFT),
1637		       (unsigned long long) stats.used,
1638		       (unsigned long long) stats.total,
1639		       (unsigned) stats.era);
1640
1641		if (stats.snap != SUPERBLOCK_LOCATION)
1642			DMEMIT(" %llu", stats.snap);
1643		else
1644			DMEMIT(" -");
1645		break;
1646
1647	case STATUSTYPE_TABLE:
1648		format_dev_t(buf, era->metadata_dev->bdev->bd_dev);
1649		DMEMIT("%s ", buf);
1650		format_dev_t(buf, era->origin_dev->bdev->bd_dev);
1651		DMEMIT("%s %u", buf, era->sectors_per_block);
1652		break;
1653
1654	case STATUSTYPE_IMA:
1655		*result = '\0';
1656		break;
1657	}
1658
1659	return;
1660
1661err:
1662	DMEMIT("Error");
1663}
1664
1665static int era_message(struct dm_target *ti, unsigned argc, char **argv,
1666		       char *result, unsigned maxlen)
1667{
1668	struct era *era = ti->private;
1669
1670	if (argc != 1) {
1671		DMERR("incorrect number of message arguments");
1672		return -EINVAL;
1673	}
1674
1675	if (!strcasecmp(argv[0], "checkpoint"))
1676		return in_worker0(era, metadata_checkpoint);
1677
1678	if (!strcasecmp(argv[0], "take_metadata_snap"))
1679		return in_worker0(era, metadata_take_snap);
1680
1681	if (!strcasecmp(argv[0], "drop_metadata_snap"))
1682		return in_worker0(era, metadata_drop_snap);
1683
1684	DMERR("unsupported message '%s'", argv[0]);
1685	return -EINVAL;
1686}
1687
1688static sector_t get_dev_size(struct dm_dev *dev)
1689{
1690	return bdev_nr_sectors(dev->bdev);
1691}
1692
1693static int era_iterate_devices(struct dm_target *ti,
1694			       iterate_devices_callout_fn fn, void *data)
1695{
1696	struct era *era = ti->private;
1697	return fn(ti, era->origin_dev, 0, get_dev_size(era->origin_dev), data);
1698}
1699
1700static void era_io_hints(struct dm_target *ti, struct queue_limits *limits)
1701{
1702	struct era *era = ti->private;
1703	uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
1704
1705	/*
1706	 * If the system-determined stacked limits are compatible with the
1707	 * era device's blocksize (io_opt is a factor) do not override them.
1708	 */
1709	if (io_opt_sectors < era->sectors_per_block ||
1710	    do_div(io_opt_sectors, era->sectors_per_block)) {
1711		blk_limits_io_min(limits, 0);
1712		blk_limits_io_opt(limits, era->sectors_per_block << SECTOR_SHIFT);
1713	}
1714}
1715
1716/*----------------------------------------------------------------*/
1717
1718static struct target_type era_target = {
1719	.name = "era",
1720	.version = {1, 0, 0},
1721	.module = THIS_MODULE,
1722	.ctr = era_ctr,
1723	.dtr = era_dtr,
1724	.map = era_map,
1725	.postsuspend = era_postsuspend,
1726	.preresume = era_preresume,
1727	.status = era_status,
1728	.message = era_message,
1729	.iterate_devices = era_iterate_devices,
1730	.io_hints = era_io_hints
1731};
1732
1733static int __init dm_era_init(void)
1734{
1735	int r;
1736
1737	r = dm_register_target(&era_target);
1738	if (r) {
1739		DMERR("era target registration failed: %d", r);
1740		return r;
1741	}
1742
1743	return 0;
1744}
1745
1746static void __exit dm_era_exit(void)
1747{
1748	dm_unregister_target(&era_target);
1749}
1750
1751module_init(dm_era_init);
1752module_exit(dm_era_exit);
1753
1754MODULE_DESCRIPTION(DM_NAME " era target");
1755MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
1756MODULE_LICENSE("GPL");