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/bio.h>
   8#include <linux/err.h>
   9#include <linux/hash.h>
  10#include <linux/list.h>
  11#include <linux/log2.h>
  12#include <linux/init.h>
  13#include <linux/slab.h>
  14#include <linux/wait.h>
  15#include <linux/dm-io.h>
  16#include <linux/mutex.h>
  17#include <linux/atomic.h>
  18#include <linux/bitops.h>
  19#include <linux/blkdev.h>
  20#include <linux/kdev_t.h>
  21#include <linux/kernel.h>
  22#include <linux/module.h>
  23#include <linux/jiffies.h>
  24#include <linux/mempool.h>
  25#include <linux/spinlock.h>
  26#include <linux/blk_types.h>
  27#include <linux/dm-kcopyd.h>
  28#include <linux/workqueue.h>
  29#include <linux/backing-dev.h>
  30#include <linux/device-mapper.h>
  31
  32#include "dm.h"
  33#include "dm-clone-metadata.h"
  34
  35#define DM_MSG_PREFIX "clone"
  36
  37/*
  38 * Minimum and maximum allowed region sizes
  39 */
  40#define MIN_REGION_SIZE (1 << 3)  /* 4KB */
  41#define MAX_REGION_SIZE (1 << 21) /* 1GB */
  42
  43#define MIN_HYDRATIONS 256 /* Size of hydration mempool */
  44#define DEFAULT_HYDRATION_THRESHOLD 1 /* 1 region */
  45#define DEFAULT_HYDRATION_BATCH_SIZE 1 /* Hydrate in batches of 1 region */
  46
  47#define COMMIT_PERIOD HZ /* 1 sec */
  48
  49/*
  50 * Hydration hash table size: 1 << HASH_TABLE_BITS
  51 */
  52#define HASH_TABLE_BITS 15
  53
  54DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(clone_hydration_throttle,
  55	"A percentage of time allocated for hydrating regions");
  56
  57/* Slab cache for struct dm_clone_region_hydration */
  58static struct kmem_cache *_hydration_cache;
  59
  60/* dm-clone metadata modes */
  61enum clone_metadata_mode {
  62	CM_WRITE,		/* metadata may be changed */
  63	CM_READ_ONLY,		/* metadata may not be changed */
  64	CM_FAIL,		/* all metadata I/O fails */
  65};
  66
  67struct hash_table_bucket;
  68
  69struct clone {
  70	struct dm_target *ti;
  71
  72	struct dm_dev *metadata_dev;
  73	struct dm_dev *dest_dev;
  74	struct dm_dev *source_dev;
  75
  76	unsigned long nr_regions;
  77	sector_t region_size;
  78	unsigned int region_shift;
  79
  80	/*
  81	 * A metadata commit and the actions taken in case it fails should run
  82	 * as a single atomic step.
  83	 */
  84	struct mutex commit_lock;
  85
  86	struct dm_clone_metadata *cmd;
  87
  88	/*
  89	 * bio used to flush the destination device, before committing the
  90	 * metadata.
  91	 */
  92	struct bio flush_bio;
  93
  94	/* Region hydration hash table */
  95	struct hash_table_bucket *ht;
  96
  97	atomic_t ios_in_flight;
  98
  99	wait_queue_head_t hydration_stopped;
 100
 101	mempool_t hydration_pool;
 102
 103	unsigned long last_commit_jiffies;
 104
 105	/*
 106	 * We defer incoming WRITE bios for regions that are not hydrated,
 107	 * until after these regions have been hydrated.
 108	 *
 109	 * Also, we defer REQ_FUA and REQ_PREFLUSH bios, until after the
 110	 * metadata have been committed.
 111	 */
 112	spinlock_t lock;
 113	struct bio_list deferred_bios;
 114	struct bio_list deferred_discard_bios;
 115	struct bio_list deferred_flush_bios;
 116	struct bio_list deferred_flush_completions;
 117
 118	/* Maximum number of regions being copied during background hydration. */
 119	unsigned int hydration_threshold;
 120
 121	/* Number of regions to batch together during background hydration. */
 122	unsigned int hydration_batch_size;
 123
 124	/* Which region to hydrate next */
 125	unsigned long hydration_offset;
 126
 127	atomic_t hydrations_in_flight;
 128
 129	/*
 130	 * Save a copy of the table line rather than reconstructing it for the
 131	 * status.
 132	 */
 133	unsigned int nr_ctr_args;
 134	const char **ctr_args;
 135
 136	struct workqueue_struct *wq;
 137	struct work_struct worker;
 138	struct delayed_work waker;
 139
 140	struct dm_kcopyd_client *kcopyd_client;
 141
 142	enum clone_metadata_mode mode;
 143	unsigned long flags;
 144};
 145
 146/*
 147 * dm-clone flags
 148 */
 149#define DM_CLONE_DISCARD_PASSDOWN 0
 150#define DM_CLONE_HYDRATION_ENABLED 1
 151#define DM_CLONE_HYDRATION_SUSPENDED 2
 152
 153/*---------------------------------------------------------------------------*/
 154
 155/*
 156 * Metadata failure handling.
 157 */
 158static enum clone_metadata_mode get_clone_mode(struct clone *clone)
 159{
 160	return READ_ONCE(clone->mode);
 161}
 162
 163static const char *clone_device_name(struct clone *clone)
 164{
 165	return dm_table_device_name(clone->ti->table);
 166}
 167
 168static void __set_clone_mode(struct clone *clone, enum clone_metadata_mode new_mode)
 169{
 170	const char *descs[] = {
 171		"read-write",
 172		"read-only",
 173		"fail"
 174	};
 175
 176	enum clone_metadata_mode old_mode = get_clone_mode(clone);
 177
 178	/* Never move out of fail mode */
 179	if (old_mode == CM_FAIL)
 180		new_mode = CM_FAIL;
 181
 182	switch (new_mode) {
 183	case CM_FAIL:
 184	case CM_READ_ONLY:
 185		dm_clone_metadata_set_read_only(clone->cmd);
 186		break;
 187
 188	case CM_WRITE:
 189		dm_clone_metadata_set_read_write(clone->cmd);
 190		break;
 191	}
 192
 193	WRITE_ONCE(clone->mode, new_mode);
 194
 195	if (new_mode != old_mode) {
 196		dm_table_event(clone->ti->table);
 197		DMINFO("%s: Switching to %s mode", clone_device_name(clone),
 198		       descs[(int)new_mode]);
 199	}
 200}
 201
 202static void __abort_transaction(struct clone *clone)
 203{
 204	const char *dev_name = clone_device_name(clone);
 205
 206	if (get_clone_mode(clone) >= CM_READ_ONLY)
 207		return;
 208
 209	DMERR("%s: Aborting current metadata transaction", dev_name);
 210	if (dm_clone_metadata_abort(clone->cmd)) {
 211		DMERR("%s: Failed to abort metadata transaction", dev_name);
 212		__set_clone_mode(clone, CM_FAIL);
 213	}
 214}
 215
 216static void __reload_in_core_bitset(struct clone *clone)
 217{
 218	const char *dev_name = clone_device_name(clone);
 219
 220	if (get_clone_mode(clone) == CM_FAIL)
 221		return;
 222
 223	/* Reload the on-disk bitset */
 224	DMINFO("%s: Reloading on-disk bitmap", dev_name);
 225	if (dm_clone_reload_in_core_bitset(clone->cmd)) {
 226		DMERR("%s: Failed to reload on-disk bitmap", dev_name);
 227		__set_clone_mode(clone, CM_FAIL);
 228	}
 229}
 230
 231static void __metadata_operation_failed(struct clone *clone, const char *op, int r)
 232{
 233	DMERR("%s: Metadata operation `%s' failed: error = %d",
 234	      clone_device_name(clone), op, r);
 235
 236	__abort_transaction(clone);
 237	__set_clone_mode(clone, CM_READ_ONLY);
 238
 239	/*
 240	 * dm_clone_reload_in_core_bitset() may run concurrently with either
 241	 * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), but
 242	 * it's safe as we have already set the metadata to read-only mode.
 243	 */
 244	__reload_in_core_bitset(clone);
 245}
 246
 247/*---------------------------------------------------------------------------*/
 248
 249/* Wake up anyone waiting for region hydrations to stop */
 250static inline void wakeup_hydration_waiters(struct clone *clone)
 251{
 252	wake_up_all(&clone->hydration_stopped);
 253}
 254
 255static inline void wake_worker(struct clone *clone)
 256{
 257	queue_work(clone->wq, &clone->worker);
 258}
 259
 260/*---------------------------------------------------------------------------*/
 261
 262/*
 263 * bio helper functions.
 264 */
 265static inline void remap_to_source(struct clone *clone, struct bio *bio)
 266{
 267	bio_set_dev(bio, clone->source_dev->bdev);
 268}
 269
 270static inline void remap_to_dest(struct clone *clone, struct bio *bio)
 271{
 272	bio_set_dev(bio, clone->dest_dev->bdev);
 273}
 274
 275static bool bio_triggers_commit(struct clone *clone, struct bio *bio)
 276{
 277	return op_is_flush(bio->bi_opf) &&
 278		dm_clone_changed_this_transaction(clone->cmd);
 279}
 280
 281/* Get the address of the region in sectors */
 282static inline sector_t region_to_sector(struct clone *clone, unsigned long region_nr)
 283{
 284	return ((sector_t)region_nr << clone->region_shift);
 285}
 286
 287/* Get the region number of the bio */
 288static inline unsigned long bio_to_region(struct clone *clone, struct bio *bio)
 289{
 290	return (bio->bi_iter.bi_sector >> clone->region_shift);
 291}
 292
 293/* Get the region range covered by the bio */
 294static void bio_region_range(struct clone *clone, struct bio *bio,
 295			     unsigned long *rs, unsigned long *nr_regions)
 296{
 297	unsigned long end;
 298
 299	*rs = dm_sector_div_up(bio->bi_iter.bi_sector, clone->region_size);
 300	end = bio_end_sector(bio) >> clone->region_shift;
 301
 302	if (*rs >= end)
 303		*nr_regions = 0;
 304	else
 305		*nr_regions = end - *rs;
 306}
 307
 308/* Check whether a bio overwrites a region */
 309static inline bool is_overwrite_bio(struct clone *clone, struct bio *bio)
 310{
 311	return (bio_data_dir(bio) == WRITE && bio_sectors(bio) == clone->region_size);
 312}
 313
 314static void fail_bios(struct bio_list *bios, blk_status_t status)
 315{
 316	struct bio *bio;
 317
 318	while ((bio = bio_list_pop(bios))) {
 319		bio->bi_status = status;
 320		bio_endio(bio);
 321	}
 322}
 323
 324static void submit_bios(struct bio_list *bios)
 325{
 326	struct bio *bio;
 327	struct blk_plug plug;
 328
 329	blk_start_plug(&plug);
 330
 331	while ((bio = bio_list_pop(bios)))
 332		submit_bio_noacct(bio);
 333
 334	blk_finish_plug(&plug);
 335}
 336
 337/*
 338 * Submit bio to the underlying device.
 339 *
 340 * If the bio triggers a commit, delay it, until after the metadata have been
 341 * committed.
 342 *
 343 * NOTE: The bio remapping must be performed by the caller.
 344 */
 345static void issue_bio(struct clone *clone, struct bio *bio)
 346{
 347	if (!bio_triggers_commit(clone, bio)) {
 348		submit_bio_noacct(bio);
 349		return;
 350	}
 351
 352	/*
 353	 * If the metadata mode is RO or FAIL we won't be able to commit the
 354	 * metadata, so we complete the bio with an error.
 355	 */
 356	if (unlikely(get_clone_mode(clone) >= CM_READ_ONLY)) {
 357		bio_io_error(bio);
 358		return;
 359	}
 360
 361	/*
 362	 * Batch together any bios that trigger commits and then issue a single
 363	 * commit for them in process_deferred_flush_bios().
 364	 */
 365	spin_lock_irq(&clone->lock);
 366	bio_list_add(&clone->deferred_flush_bios, bio);
 367	spin_unlock_irq(&clone->lock);
 368
 369	wake_worker(clone);
 370}
 371
 372/*
 373 * Remap bio to the destination device and submit it.
 374 *
 375 * If the bio triggers a commit, delay it, until after the metadata have been
 376 * committed.
 377 */
 378static void remap_and_issue(struct clone *clone, struct bio *bio)
 379{
 380	remap_to_dest(clone, bio);
 381	issue_bio(clone, bio);
 382}
 383
 384/*
 385 * Issue bios that have been deferred until after their region has finished
 386 * hydrating.
 387 *
 388 * We delegate the bio submission to the worker thread, so this is safe to call
 389 * from interrupt context.
 390 */
 391static void issue_deferred_bios(struct clone *clone, struct bio_list *bios)
 392{
 393	struct bio *bio;
 394	unsigned long flags;
 395	struct bio_list flush_bios = BIO_EMPTY_LIST;
 396	struct bio_list normal_bios = BIO_EMPTY_LIST;
 397
 398	if (bio_list_empty(bios))
 399		return;
 400
 401	while ((bio = bio_list_pop(bios))) {
 402		if (bio_triggers_commit(clone, bio))
 403			bio_list_add(&flush_bios, bio);
 404		else
 405			bio_list_add(&normal_bios, bio);
 406	}
 407
 408	spin_lock_irqsave(&clone->lock, flags);
 409	bio_list_merge(&clone->deferred_bios, &normal_bios);
 410	bio_list_merge(&clone->deferred_flush_bios, &flush_bios);
 411	spin_unlock_irqrestore(&clone->lock, flags);
 412
 413	wake_worker(clone);
 414}
 415
 416static void complete_overwrite_bio(struct clone *clone, struct bio *bio)
 417{
 418	unsigned long flags;
 419
 420	/*
 421	 * If the bio has the REQ_FUA flag set we must commit the metadata
 422	 * before signaling its completion.
 423	 *
 424	 * complete_overwrite_bio() is only called by hydration_complete(),
 425	 * after having successfully updated the metadata. This means we don't
 426	 * need to call dm_clone_changed_this_transaction() to check if the
 427	 * metadata has changed and thus we can avoid taking the metadata spin
 428	 * lock.
 429	 */
 430	if (!(bio->bi_opf & REQ_FUA)) {
 431		bio_endio(bio);
 432		return;
 433	}
 434
 435	/*
 436	 * If the metadata mode is RO or FAIL we won't be able to commit the
 437	 * metadata, so we complete the bio with an error.
 438	 */
 439	if (unlikely(get_clone_mode(clone) >= CM_READ_ONLY)) {
 440		bio_io_error(bio);
 441		return;
 442	}
 443
 444	/*
 445	 * Batch together any bios that trigger commits and then issue a single
 446	 * commit for them in process_deferred_flush_bios().
 447	 */
 448	spin_lock_irqsave(&clone->lock, flags);
 449	bio_list_add(&clone->deferred_flush_completions, bio);
 450	spin_unlock_irqrestore(&clone->lock, flags);
 451
 452	wake_worker(clone);
 453}
 454
 455static void trim_bio(struct bio *bio, sector_t sector, unsigned int len)
 456{
 457	bio->bi_iter.bi_sector = sector;
 458	bio->bi_iter.bi_size = to_bytes(len);
 459}
 460
 461static void complete_discard_bio(struct clone *clone, struct bio *bio, bool success)
 462{
 463	unsigned long rs, nr_regions;
 464
 465	/*
 466	 * If the destination device supports discards, remap and trim the
 467	 * discard bio and pass it down. Otherwise complete the bio
 468	 * immediately.
 469	 */
 470	if (test_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags) && success) {
 471		remap_to_dest(clone, bio);
 472		bio_region_range(clone, bio, &rs, &nr_regions);
 473		trim_bio(bio, region_to_sector(clone, rs),
 474			 nr_regions << clone->region_shift);
 475		submit_bio_noacct(bio);
 476	} else
 477		bio_endio(bio);
 478}
 479
 480static void process_discard_bio(struct clone *clone, struct bio *bio)
 481{
 482	unsigned long rs, nr_regions;
 483
 484	bio_region_range(clone, bio, &rs, &nr_regions);
 485	if (!nr_regions) {
 486		bio_endio(bio);
 487		return;
 488	}
 489
 490	if (WARN_ON(rs >= clone->nr_regions || (rs + nr_regions) < rs ||
 491		    (rs + nr_regions) > clone->nr_regions)) {
 492		DMERR("%s: Invalid range (%lu + %lu, total regions %lu) for discard (%llu + %u)",
 493		      clone_device_name(clone), rs, nr_regions,
 494		      clone->nr_regions,
 495		      (unsigned long long)bio->bi_iter.bi_sector,
 496		      bio_sectors(bio));
 497		bio_endio(bio);
 498		return;
 499	}
 500
 501	/*
 502	 * The covered regions are already hydrated so we just need to pass
 503	 * down the discard.
 504	 */
 505	if (dm_clone_is_range_hydrated(clone->cmd, rs, nr_regions)) {
 506		complete_discard_bio(clone, bio, true);
 507		return;
 508	}
 509
 510	/*
 511	 * If the metadata mode is RO or FAIL we won't be able to update the
 512	 * metadata for the regions covered by the discard so we just ignore
 513	 * it.
 514	 */
 515	if (unlikely(get_clone_mode(clone) >= CM_READ_ONLY)) {
 516		bio_endio(bio);
 517		return;
 518	}
 519
 520	/*
 521	 * Defer discard processing.
 522	 */
 523	spin_lock_irq(&clone->lock);
 524	bio_list_add(&clone->deferred_discard_bios, bio);
 525	spin_unlock_irq(&clone->lock);
 526
 527	wake_worker(clone);
 528}
 529
 530/*---------------------------------------------------------------------------*/
 531
 532/*
 533 * dm-clone region hydrations.
 534 */
 535struct dm_clone_region_hydration {
 536	struct clone *clone;
 537	unsigned long region_nr;
 538
 539	struct bio *overwrite_bio;
 540	bio_end_io_t *overwrite_bio_end_io;
 541
 542	struct bio_list deferred_bios;
 543
 544	blk_status_t status;
 545
 546	/* Used by hydration batching */
 547	struct list_head list;
 548
 549	/* Used by hydration hash table */
 550	struct hlist_node h;
 551};
 552
 553/*
 554 * Hydration hash table implementation.
 555 *
 556 * Ideally we would like to use list_bl, which uses bit spin locks and employs
 557 * the least significant bit of the list head to lock the corresponding bucket,
 558 * reducing the memory overhead for the locks. But, currently, list_bl and bit
 559 * spin locks don't support IRQ safe versions. Since we have to take the lock
 560 * in both process and interrupt context, we must fall back to using regular
 561 * spin locks; one per hash table bucket.
 562 */
 563struct hash_table_bucket {
 564	struct hlist_head head;
 565
 566	/* Spinlock protecting the bucket */
 567	spinlock_t lock;
 568};
 569
 570#define bucket_lock_irqsave(bucket, flags) \
 571	spin_lock_irqsave(&(bucket)->lock, flags)
 572
 573#define bucket_unlock_irqrestore(bucket, flags) \
 574	spin_unlock_irqrestore(&(bucket)->lock, flags)
 575
 576#define bucket_lock_irq(bucket) \
 577	spin_lock_irq(&(bucket)->lock)
 578
 579#define bucket_unlock_irq(bucket) \
 580	spin_unlock_irq(&(bucket)->lock)
 581
 582static int hash_table_init(struct clone *clone)
 583{
 584	unsigned int i, sz;
 585	struct hash_table_bucket *bucket;
 586
 587	sz = 1 << HASH_TABLE_BITS;
 588
 589	clone->ht = kvmalloc(sz * sizeof(struct hash_table_bucket), GFP_KERNEL);
 590	if (!clone->ht)
 591		return -ENOMEM;
 592
 593	for (i = 0; i < sz; i++) {
 594		bucket = clone->ht + i;
 595
 596		INIT_HLIST_HEAD(&bucket->head);
 597		spin_lock_init(&bucket->lock);
 598	}
 599
 600	return 0;
 601}
 602
 603static void hash_table_exit(struct clone *clone)
 604{
 605	kvfree(clone->ht);
 606}
 607
 608static struct hash_table_bucket *get_hash_table_bucket(struct clone *clone,
 609						       unsigned long region_nr)
 610{
 611	return &clone->ht[hash_long(region_nr, HASH_TABLE_BITS)];
 612}
 613
 614/*
 615 * Search hash table for a hydration with hd->region_nr == region_nr
 616 *
 617 * NOTE: Must be called with the bucket lock held
 618 */
 619static struct dm_clone_region_hydration *__hash_find(struct hash_table_bucket *bucket,
 620						     unsigned long region_nr)
 621{
 622	struct dm_clone_region_hydration *hd;
 623
 624	hlist_for_each_entry(hd, &bucket->head, h) {
 625		if (hd->region_nr == region_nr)
 626			return hd;
 627	}
 628
 629	return NULL;
 630}
 631
 632/*
 633 * Insert a hydration into the hash table.
 634 *
 635 * NOTE: Must be called with the bucket lock held.
 636 */
 637static inline void __insert_region_hydration(struct hash_table_bucket *bucket,
 638					     struct dm_clone_region_hydration *hd)
 639{
 640	hlist_add_head(&hd->h, &bucket->head);
 641}
 642
 643/*
 644 * This function inserts a hydration into the hash table, unless someone else
 645 * managed to insert a hydration for the same region first. In the latter case
 646 * it returns the existing hydration descriptor for this region.
 647 *
 648 * NOTE: Must be called with the hydration hash table lock held.
 649 */
 650static struct dm_clone_region_hydration *
 651__find_or_insert_region_hydration(struct hash_table_bucket *bucket,
 652				  struct dm_clone_region_hydration *hd)
 653{
 654	struct dm_clone_region_hydration *hd2;
 655
 656	hd2 = __hash_find(bucket, hd->region_nr);
 657	if (hd2)
 658		return hd2;
 659
 660	__insert_region_hydration(bucket, hd);
 661
 662	return hd;
 663}
 664
 665/*---------------------------------------------------------------------------*/
 666
 667/* Allocate a hydration */
 668static struct dm_clone_region_hydration *alloc_hydration(struct clone *clone)
 669{
 670	struct dm_clone_region_hydration *hd;
 671
 672	/*
 673	 * Allocate a hydration from the hydration mempool.
 674	 * This might block but it can't fail.
 675	 */
 676	hd = mempool_alloc(&clone->hydration_pool, GFP_NOIO);
 677	hd->clone = clone;
 678
 679	return hd;
 680}
 681
 682static inline void free_hydration(struct dm_clone_region_hydration *hd)
 683{
 684	mempool_free(hd, &hd->clone->hydration_pool);
 685}
 686
 687/* Initialize a hydration */
 688static void hydration_init(struct dm_clone_region_hydration *hd, unsigned long region_nr)
 689{
 690	hd->region_nr = region_nr;
 691	hd->overwrite_bio = NULL;
 692	bio_list_init(&hd->deferred_bios);
 693	hd->status = 0;
 694
 695	INIT_LIST_HEAD(&hd->list);
 696	INIT_HLIST_NODE(&hd->h);
 697}
 698
 699/*---------------------------------------------------------------------------*/
 700
 701/*
 702 * Update dm-clone's metadata after a region has finished hydrating and remove
 703 * hydration from the hash table.
 704 */
 705static int hydration_update_metadata(struct dm_clone_region_hydration *hd)
 706{
 707	int r = 0;
 708	unsigned long flags;
 709	struct hash_table_bucket *bucket;
 710	struct clone *clone = hd->clone;
 711
 712	if (unlikely(get_clone_mode(clone) >= CM_READ_ONLY))
 713		r = -EPERM;
 714
 715	/* Update the metadata */
 716	if (likely(!r) && hd->status == BLK_STS_OK)
 717		r = dm_clone_set_region_hydrated(clone->cmd, hd->region_nr);
 718
 719	bucket = get_hash_table_bucket(clone, hd->region_nr);
 720
 721	/* Remove hydration from hash table */
 722	bucket_lock_irqsave(bucket, flags);
 723	hlist_del(&hd->h);
 724	bucket_unlock_irqrestore(bucket, flags);
 725
 726	return r;
 727}
 728
 729/*
 730 * Complete a region's hydration:
 731 *
 732 *	1. Update dm-clone's metadata.
 733 *	2. Remove hydration from hash table.
 734 *	3. Complete overwrite bio.
 735 *	4. Issue deferred bios.
 736 *	5. If this was the last hydration, wake up anyone waiting for
 737 *	   hydrations to finish.
 738 */
 739static void hydration_complete(struct dm_clone_region_hydration *hd)
 740{
 741	int r;
 742	blk_status_t status;
 743	struct clone *clone = hd->clone;
 744
 745	r = hydration_update_metadata(hd);
 746
 747	if (hd->status == BLK_STS_OK && likely(!r)) {
 748		if (hd->overwrite_bio)
 749			complete_overwrite_bio(clone, hd->overwrite_bio);
 750
 751		issue_deferred_bios(clone, &hd->deferred_bios);
 752	} else {
 753		status = r ? BLK_STS_IOERR : hd->status;
 754
 755		if (hd->overwrite_bio)
 756			bio_list_add(&hd->deferred_bios, hd->overwrite_bio);
 757
 758		fail_bios(&hd->deferred_bios, status);
 759	}
 760
 761	free_hydration(hd);
 762
 763	if (atomic_dec_and_test(&clone->hydrations_in_flight))
 764		wakeup_hydration_waiters(clone);
 765}
 766
 767static void hydration_kcopyd_callback(int read_err, unsigned long write_err, void *context)
 768{
 769	blk_status_t status;
 770
 771	struct dm_clone_region_hydration *tmp, *hd = context;
 772	struct clone *clone = hd->clone;
 773
 774	LIST_HEAD(batched_hydrations);
 775
 776	if (read_err || write_err) {
 777		DMERR_LIMIT("%s: hydration failed", clone_device_name(clone));
 778		status = BLK_STS_IOERR;
 779	} else {
 780		status = BLK_STS_OK;
 781	}
 782	list_splice_tail(&hd->list, &batched_hydrations);
 783
 784	hd->status = status;
 785	hydration_complete(hd);
 786
 787	/* Complete batched hydrations */
 788	list_for_each_entry_safe(hd, tmp, &batched_hydrations, list) {
 789		hd->status = status;
 790		hydration_complete(hd);
 791	}
 792
 793	/* Continue background hydration, if there is no I/O in-flight */
 794	if (test_bit(DM_CLONE_HYDRATION_ENABLED, &clone->flags) &&
 795	    !atomic_read(&clone->ios_in_flight))
 796		wake_worker(clone);
 797}
 798
 799static void hydration_copy(struct dm_clone_region_hydration *hd, unsigned int nr_regions)
 800{
 801	unsigned long region_start, region_end;
 802	sector_t tail_size, region_size, total_size;
 803	struct dm_io_region from, to;
 804	struct clone *clone = hd->clone;
 805
 806	if (WARN_ON(!nr_regions))
 807		return;
 808
 809	region_size = clone->region_size;
 810	region_start = hd->region_nr;
 811	region_end = region_start + nr_regions - 1;
 812
 813	total_size = region_to_sector(clone, nr_regions - 1);
 814
 815	if (region_end == clone->nr_regions - 1) {
 816		/*
 817		 * The last region of the target might be smaller than
 818		 * region_size.
 819		 */
 820		tail_size = clone->ti->len & (region_size - 1);
 821		if (!tail_size)
 822			tail_size = region_size;
 823	} else {
 824		tail_size = region_size;
 825	}
 826
 827	total_size += tail_size;
 828
 829	from.bdev = clone->source_dev->bdev;
 830	from.sector = region_to_sector(clone, region_start);
 831	from.count = total_size;
 832
 833	to.bdev = clone->dest_dev->bdev;
 834	to.sector = from.sector;
 835	to.count = from.count;
 836
 837	/* Issue copy */
 838	atomic_add(nr_regions, &clone->hydrations_in_flight);
 839	dm_kcopyd_copy(clone->kcopyd_client, &from, 1, &to, 0,
 840		       hydration_kcopyd_callback, hd);
 841}
 842
 843static void overwrite_endio(struct bio *bio)
 844{
 845	struct dm_clone_region_hydration *hd = bio->bi_private;
 846
 847	bio->bi_end_io = hd->overwrite_bio_end_io;
 848	hd->status = bio->bi_status;
 849
 850	hydration_complete(hd);
 851}
 852
 853static void hydration_overwrite(struct dm_clone_region_hydration *hd, struct bio *bio)
 854{
 855	/*
 856	 * We don't need to save and restore bio->bi_private because device
 857	 * mapper core generates a new bio for us to use, with clean
 858	 * bi_private.
 859	 */
 860	hd->overwrite_bio = bio;
 861	hd->overwrite_bio_end_io = bio->bi_end_io;
 862
 863	bio->bi_end_io = overwrite_endio;
 864	bio->bi_private = hd;
 865
 866	atomic_inc(&hd->clone->hydrations_in_flight);
 867	submit_bio_noacct(bio);
 868}
 869
 870/*
 871 * Hydrate bio's region.
 872 *
 873 * This function starts the hydration of the bio's region and puts the bio in
 874 * the list of deferred bios for this region. In case, by the time this
 875 * function is called, the region has finished hydrating it's submitted to the
 876 * destination device.
 877 *
 878 * NOTE: The bio remapping must be performed by the caller.
 879 */
 880static void hydrate_bio_region(struct clone *clone, struct bio *bio)
 881{
 882	unsigned long region_nr;
 883	struct hash_table_bucket *bucket;
 884	struct dm_clone_region_hydration *hd, *hd2;
 885
 886	region_nr = bio_to_region(clone, bio);
 887	bucket = get_hash_table_bucket(clone, region_nr);
 888
 889	bucket_lock_irq(bucket);
 890
 891	hd = __hash_find(bucket, region_nr);
 892	if (hd) {
 893		/* Someone else is hydrating the region */
 894		bio_list_add(&hd->deferred_bios, bio);
 895		bucket_unlock_irq(bucket);
 896		return;
 897	}
 898
 899	if (dm_clone_is_region_hydrated(clone->cmd, region_nr)) {
 900		/* The region has been hydrated */
 901		bucket_unlock_irq(bucket);
 902		issue_bio(clone, bio);
 903		return;
 904	}
 905
 906	/*
 907	 * We must allocate a hydration descriptor and start the hydration of
 908	 * the corresponding region.
 909	 */
 910	bucket_unlock_irq(bucket);
 911
 912	hd = alloc_hydration(clone);
 913	hydration_init(hd, region_nr);
 914
 915	bucket_lock_irq(bucket);
 916
 917	/* Check if the region has been hydrated in the meantime. */
 918	if (dm_clone_is_region_hydrated(clone->cmd, region_nr)) {
 919		bucket_unlock_irq(bucket);
 920		free_hydration(hd);
 921		issue_bio(clone, bio);
 922		return;
 923	}
 924
 925	hd2 = __find_or_insert_region_hydration(bucket, hd);
 926	if (hd2 != hd) {
 927		/* Someone else started the region's hydration. */
 928		bio_list_add(&hd2->deferred_bios, bio);
 929		bucket_unlock_irq(bucket);
 930		free_hydration(hd);
 931		return;
 932	}
 933
 934	/*
 935	 * If the metadata mode is RO or FAIL then there is no point starting a
 936	 * hydration, since we will not be able to update the metadata when the
 937	 * hydration finishes.
 938	 */
 939	if (unlikely(get_clone_mode(clone) >= CM_READ_ONLY)) {
 940		hlist_del(&hd->h);
 941		bucket_unlock_irq(bucket);
 942		free_hydration(hd);
 943		bio_io_error(bio);
 944		return;
 945	}
 946
 947	/*
 948	 * Start region hydration.
 949	 *
 950	 * If a bio overwrites a region, i.e., its size is equal to the
 951	 * region's size, then we don't need to copy the region from the source
 952	 * to the destination device.
 953	 */
 954	if (is_overwrite_bio(clone, bio)) {
 955		bucket_unlock_irq(bucket);
 956		hydration_overwrite(hd, bio);
 957	} else {
 958		bio_list_add(&hd->deferred_bios, bio);
 959		bucket_unlock_irq(bucket);
 960		hydration_copy(hd, 1);
 961	}
 962}
 963
 964/*---------------------------------------------------------------------------*/
 965
 966/*
 967 * Background hydrations.
 968 */
 969
 970/*
 971 * Batch region hydrations.
 972 *
 973 * To better utilize device bandwidth we batch together the hydration of
 974 * adjacent regions. This allows us to use small region sizes, e.g., 4KB, which
 975 * is good for small, random write performance (because of the overwriting of
 976 * un-hydrated regions) and at the same time issue big copy requests to kcopyd
 977 * to achieve high hydration bandwidth.
 978 */
 979struct batch_info {
 980	struct dm_clone_region_hydration *head;
 981	unsigned int nr_batched_regions;
 982};
 983
 984static void __batch_hydration(struct batch_info *batch,
 985			      struct dm_clone_region_hydration *hd)
 986{
 987	struct clone *clone = hd->clone;
 988	unsigned int max_batch_size = READ_ONCE(clone->hydration_batch_size);
 989
 990	if (batch->head) {
 991		/* Try to extend the current batch */
 992		if (batch->nr_batched_regions < max_batch_size &&
 993		    (batch->head->region_nr + batch->nr_batched_regions) == hd->region_nr) {
 994			list_add_tail(&hd->list, &batch->head->list);
 995			batch->nr_batched_regions++;
 996			hd = NULL;
 997		}
 998
 999		/* Check if we should issue the current batch */
1000		if (batch->nr_batched_regions >= max_batch_size || hd) {
1001			hydration_copy(batch->head, batch->nr_batched_regions);
1002			batch->head = NULL;
1003			batch->nr_batched_regions = 0;
1004		}
1005	}
1006
1007	if (!hd)
1008		return;
1009
1010	/* We treat max batch sizes of zero and one equivalently */
1011	if (max_batch_size <= 1) {
1012		hydration_copy(hd, 1);
1013		return;
1014	}
1015
1016	/* Start a new batch */
1017	BUG_ON(!list_empty(&hd->list));
1018	batch->head = hd;
1019	batch->nr_batched_regions = 1;
1020}
1021
1022static unsigned long __start_next_hydration(struct clone *clone,
1023					    unsigned long offset,
1024					    struct batch_info *batch)
1025{
1026	struct hash_table_bucket *bucket;
1027	struct dm_clone_region_hydration *hd;
1028	unsigned long nr_regions = clone->nr_regions;
1029
1030	hd = alloc_hydration(clone);
1031
1032	/* Try to find a region to hydrate. */
1033	do {
1034		offset = dm_clone_find_next_unhydrated_region(clone->cmd, offset);
1035		if (offset == nr_regions)
1036			break;
1037
1038		bucket = get_hash_table_bucket(clone, offset);
1039		bucket_lock_irq(bucket);
1040
1041		if (!dm_clone_is_region_hydrated(clone->cmd, offset) &&
1042		    !__hash_find(bucket, offset)) {
1043			hydration_init(hd, offset);
1044			__insert_region_hydration(bucket, hd);
1045			bucket_unlock_irq(bucket);
1046
1047			/* Batch hydration */
1048			__batch_hydration(batch, hd);
1049
1050			return (offset + 1);
1051		}
1052
1053		bucket_unlock_irq(bucket);
1054
1055	} while (++offset < nr_regions);
1056
1057	if (hd)
1058		free_hydration(hd);
1059
1060	return offset;
1061}
1062
1063/*
1064 * This function searches for regions that still reside in the source device
1065 * and starts their hydration.
1066 */
1067static void do_hydration(struct clone *clone)
1068{
1069	unsigned int current_volume;
1070	unsigned long offset, nr_regions = clone->nr_regions;
1071
1072	struct batch_info batch = {
1073		.head = NULL,
1074		.nr_batched_regions = 0,
1075	};
1076
1077	if (unlikely(get_clone_mode(clone) >= CM_READ_ONLY))
1078		return;
1079
1080	if (dm_clone_is_hydration_done(clone->cmd))
1081		return;
1082
1083	/*
1084	 * Avoid race with device suspension.
1085	 */
1086	atomic_inc(&clone->hydrations_in_flight);
1087
1088	/*
1089	 * Make sure atomic_inc() is ordered before test_bit(), otherwise we
1090	 * might race with clone_postsuspend() and start a region hydration
1091	 * after the target has been suspended.
1092	 *
1093	 * This is paired with the smp_mb__after_atomic() in
1094	 * clone_postsuspend().
1095	 */
1096	smp_mb__after_atomic();
1097
1098	offset = clone->hydration_offset;
1099	while (likely(!test_bit(DM_CLONE_HYDRATION_SUSPENDED, &clone->flags)) &&
1100	       !atomic_read(&clone->ios_in_flight) &&
1101	       test_bit(DM_CLONE_HYDRATION_ENABLED, &clone->flags) &&
1102	       offset < nr_regions) {
1103		current_volume = atomic_read(&clone->hydrations_in_flight);
1104		current_volume += batch.nr_batched_regions;
1105
1106		if (current_volume > READ_ONCE(clone->hydration_threshold))
1107			break;
1108
1109		offset = __start_next_hydration(clone, offset, &batch);
1110	}
1111
1112	if (batch.head)
1113		hydration_copy(batch.head, batch.nr_batched_regions);
1114
1115	if (offset >= nr_regions)
1116		offset = 0;
1117
1118	clone->hydration_offset = offset;
1119
1120	if (atomic_dec_and_test(&clone->hydrations_in_flight))
1121		wakeup_hydration_waiters(clone);
1122}
1123
1124/*---------------------------------------------------------------------------*/
1125
1126static bool need_commit_due_to_time(struct clone *clone)
1127{
1128	return !time_in_range(jiffies, clone->last_commit_jiffies,
1129			      clone->last_commit_jiffies + COMMIT_PERIOD);
1130}
1131
1132/*
1133 * A non-zero return indicates read-only or fail mode.
1134 */
1135static int commit_metadata(struct clone *clone, bool *dest_dev_flushed)
1136{
1137	int r = 0;
1138
1139	if (dest_dev_flushed)
1140		*dest_dev_flushed = false;
1141
1142	mutex_lock(&clone->commit_lock);
1143
1144	if (!dm_clone_changed_this_transaction(clone->cmd))
1145		goto out;
1146
1147	if (unlikely(get_clone_mode(clone) >= CM_READ_ONLY)) {
1148		r = -EPERM;
1149		goto out;
1150	}
1151
1152	r = dm_clone_metadata_pre_commit(clone->cmd);
1153	if (unlikely(r)) {
1154		__metadata_operation_failed(clone, "dm_clone_metadata_pre_commit", r);
1155		goto out;
1156	}
1157
1158	bio_reset(&clone->flush_bio);
1159	bio_set_dev(&clone->flush_bio, clone->dest_dev->bdev);
1160	clone->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
1161
1162	r = submit_bio_wait(&clone->flush_bio);
1163	if (unlikely(r)) {
1164		__metadata_operation_failed(clone, "flush destination device", r);
1165		goto out;
1166	}
1167
1168	if (dest_dev_flushed)
1169		*dest_dev_flushed = true;
1170
1171	r = dm_clone_metadata_commit(clone->cmd);
1172	if (unlikely(r)) {
1173		__metadata_operation_failed(clone, "dm_clone_metadata_commit", r);
1174		goto out;
1175	}
1176
1177	if (dm_clone_is_hydration_done(clone->cmd))
1178		dm_table_event(clone->ti->table);
1179out:
1180	mutex_unlock(&clone->commit_lock);
1181
1182	return r;
1183}
1184
1185static void process_deferred_discards(struct clone *clone)
1186{
1187	int r = -EPERM;
1188	struct bio *bio;
1189	struct blk_plug plug;
1190	unsigned long rs, nr_regions;
1191	struct bio_list discards = BIO_EMPTY_LIST;
1192
1193	spin_lock_irq(&clone->lock);
1194	bio_list_merge(&discards, &clone->deferred_discard_bios);
1195	bio_list_init(&clone->deferred_discard_bios);
1196	spin_unlock_irq(&clone->lock);
1197
1198	if (bio_list_empty(&discards))
1199		return;
1200
1201	if (unlikely(get_clone_mode(clone) >= CM_READ_ONLY))
1202		goto out;
1203
1204	/* Update the metadata */
1205	bio_list_for_each(bio, &discards) {
1206		bio_region_range(clone, bio, &rs, &nr_regions);
1207		/*
1208		 * A discard request might cover regions that have been already
1209		 * hydrated. There is no need to update the metadata for these
1210		 * regions.
1211		 */
1212		r = dm_clone_cond_set_range(clone->cmd, rs, nr_regions);
1213		if (unlikely(r))
1214			break;
1215	}
1216out:
1217	blk_start_plug(&plug);
1218	while ((bio = bio_list_pop(&discards)))
1219		complete_discard_bio(clone, bio, r == 0);
1220	blk_finish_plug(&plug);
1221}
1222
1223static void process_deferred_bios(struct clone *clone)
1224{
1225	struct bio_list bios = BIO_EMPTY_LIST;
1226
1227	spin_lock_irq(&clone->lock);
1228	bio_list_merge(&bios, &clone->deferred_bios);
1229	bio_list_init(&clone->deferred_bios);
1230	spin_unlock_irq(&clone->lock);
1231
1232	if (bio_list_empty(&bios))
1233		return;
1234
1235	submit_bios(&bios);
1236}
1237
1238static void process_deferred_flush_bios(struct clone *clone)
1239{
1240	struct bio *bio;
1241	bool dest_dev_flushed;
1242	struct bio_list bios = BIO_EMPTY_LIST;
1243	struct bio_list bio_completions = BIO_EMPTY_LIST;
1244
1245	/*
1246	 * If there are any deferred flush bios, we must commit the metadata
1247	 * before issuing them or signaling their completion.
1248	 */
1249	spin_lock_irq(&clone->lock);
1250	bio_list_merge(&bios, &clone->deferred_flush_bios);
1251	bio_list_init(&clone->deferred_flush_bios);
1252
1253	bio_list_merge(&bio_completions, &clone->deferred_flush_completions);
1254	bio_list_init(&clone->deferred_flush_completions);
1255	spin_unlock_irq(&clone->lock);
1256
1257	if (bio_list_empty(&bios) && bio_list_empty(&bio_completions) &&
1258	    !(dm_clone_changed_this_transaction(clone->cmd) && need_commit_due_to_time(clone)))
1259		return;
1260
1261	if (commit_metadata(clone, &dest_dev_flushed)) {
1262		bio_list_merge(&bios, &bio_completions);
1263
1264		while ((bio = bio_list_pop(&bios)))
1265			bio_io_error(bio);
1266
1267		return;
1268	}
1269
1270	clone->last_commit_jiffies = jiffies;
1271
1272	while ((bio = bio_list_pop(&bio_completions)))
1273		bio_endio(bio);
1274
1275	while ((bio = bio_list_pop(&bios))) {
1276		if ((bio->bi_opf & REQ_PREFLUSH) && dest_dev_flushed) {
1277			/* We just flushed the destination device as part of
1278			 * the metadata commit, so there is no reason to send
1279			 * another flush.
1280			 */
1281			bio_endio(bio);
1282		} else {
1283			submit_bio_noacct(bio);
1284		}
1285	}
1286}
1287
1288static void do_worker(struct work_struct *work)
1289{
1290	struct clone *clone = container_of(work, typeof(*clone), worker);
1291
1292	process_deferred_bios(clone);
1293	process_deferred_discards(clone);
1294
1295	/*
1296	 * process_deferred_flush_bios():
1297	 *
1298	 *   - Commit metadata
1299	 *
1300	 *   - Process deferred REQ_FUA completions
1301	 *
1302	 *   - Process deferred REQ_PREFLUSH bios
1303	 */
1304	process_deferred_flush_bios(clone);
1305
1306	/* Background hydration */
1307	do_hydration(clone);
1308}
1309
1310/*
1311 * Commit periodically so that not too much unwritten data builds up.
1312 *
1313 * Also, restart background hydration, if it has been stopped by in-flight I/O.
1314 */
1315static void do_waker(struct work_struct *work)
1316{
1317	struct clone *clone = container_of(to_delayed_work(work), struct clone, waker);
1318
1319	wake_worker(clone);
1320	queue_delayed_work(clone->wq, &clone->waker, COMMIT_PERIOD);
1321}
1322
1323/*---------------------------------------------------------------------------*/
1324
1325/*
1326 * Target methods
1327 */
1328static int clone_map(struct dm_target *ti, struct bio *bio)
1329{
1330	struct clone *clone = ti->private;
1331	unsigned long region_nr;
1332
1333	atomic_inc(&clone->ios_in_flight);
1334
1335	if (unlikely(get_clone_mode(clone) == CM_FAIL))
1336		return DM_MAPIO_KILL;
1337
1338	/*
1339	 * REQ_PREFLUSH bios carry no data:
1340	 *
1341	 * - Commit metadata, if changed
1342	 *
1343	 * - Pass down to destination device
1344	 */
1345	if (bio->bi_opf & REQ_PREFLUSH) {
1346		remap_and_issue(clone, bio);
1347		return DM_MAPIO_SUBMITTED;
1348	}
1349
1350	bio->bi_iter.bi_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
1351
1352	/*
1353	 * dm-clone interprets discards and performs a fast hydration of the
1354	 * discarded regions, i.e., we skip the copy from the source device and
1355	 * just mark the regions as hydrated.
1356	 */
1357	if (bio_op(bio) == REQ_OP_DISCARD) {
1358		process_discard_bio(clone, bio);
1359		return DM_MAPIO_SUBMITTED;
1360	}
1361
1362	/*
1363	 * If the bio's region is hydrated, redirect it to the destination
1364	 * device.
1365	 *
1366	 * If the region is not hydrated and the bio is a READ, redirect it to
1367	 * the source device.
1368	 *
1369	 * Else, defer WRITE bio until after its region has been hydrated and
1370	 * start the region's hydration immediately.
1371	 */
1372	region_nr = bio_to_region(clone, bio);
1373	if (dm_clone_is_region_hydrated(clone->cmd, region_nr)) {
1374		remap_and_issue(clone, bio);
1375		return DM_MAPIO_SUBMITTED;
1376	} else if (bio_data_dir(bio) == READ) {
1377		remap_to_source(clone, bio);
1378		return DM_MAPIO_REMAPPED;
1379	}
1380
1381	remap_to_dest(clone, bio);
1382	hydrate_bio_region(clone, bio);
1383
1384	return DM_MAPIO_SUBMITTED;
1385}
1386
1387static int clone_endio(struct dm_target *ti, struct bio *bio, blk_status_t *error)
1388{
1389	struct clone *clone = ti->private;
1390
1391	atomic_dec(&clone->ios_in_flight);
1392
1393	return DM_ENDIO_DONE;
1394}
1395
1396static void emit_flags(struct clone *clone, char *result, unsigned int maxlen,
1397		       ssize_t *sz_ptr)
1398{
1399	ssize_t sz = *sz_ptr;
1400	unsigned int count;
1401
1402	count = !test_bit(DM_CLONE_HYDRATION_ENABLED, &clone->flags);
1403	count += !test_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags);
1404
1405	DMEMIT("%u ", count);
1406
1407	if (!test_bit(DM_CLONE_HYDRATION_ENABLED, &clone->flags))
1408		DMEMIT("no_hydration ");
1409
1410	if (!test_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags))
1411		DMEMIT("no_discard_passdown ");
1412
1413	*sz_ptr = sz;
1414}
1415
1416static void emit_core_args(struct clone *clone, char *result,
1417			   unsigned int maxlen, ssize_t *sz_ptr)
1418{
1419	ssize_t sz = *sz_ptr;
1420	unsigned int count = 4;
1421
1422	DMEMIT("%u hydration_threshold %u hydration_batch_size %u ", count,
1423	       READ_ONCE(clone->hydration_threshold),
1424	       READ_ONCE(clone->hydration_batch_size));
1425
1426	*sz_ptr = sz;
1427}
1428
1429/*
1430 * Status format:
1431 *
1432 * <metadata block size> <#used metadata blocks>/<#total metadata blocks>
1433 * <clone region size> <#hydrated regions>/<#total regions> <#hydrating regions>
1434 * <#features> <features>* <#core args> <core args>* <clone metadata mode>
1435 */
1436static void clone_status(struct dm_target *ti, status_type_t type,
1437			 unsigned int status_flags, char *result,
1438			 unsigned int maxlen)
1439{
1440	int r;
1441	unsigned int i;
1442	ssize_t sz = 0;
1443	dm_block_t nr_free_metadata_blocks = 0;
1444	dm_block_t nr_metadata_blocks = 0;
1445	char buf[BDEVNAME_SIZE];
1446	struct clone *clone = ti->private;
1447
1448	switch (type) {
1449	case STATUSTYPE_INFO:
1450		if (get_clone_mode(clone) == CM_FAIL) {
1451			DMEMIT("Fail");
1452			break;
1453		}
1454
1455		/* Commit to ensure statistics aren't out-of-date */
1456		if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
1457			(void) commit_metadata(clone, NULL);
1458
1459		r = dm_clone_get_free_metadata_block_count(clone->cmd, &nr_free_metadata_blocks);
1460
1461		if (r) {
1462			DMERR("%s: dm_clone_get_free_metadata_block_count returned %d",
1463			      clone_device_name(clone), r);
1464			goto error;
1465		}
1466
1467		r = dm_clone_get_metadata_dev_size(clone->cmd, &nr_metadata_blocks);
1468
1469		if (r) {
1470			DMERR("%s: dm_clone_get_metadata_dev_size returned %d",
1471			      clone_device_name(clone), r);
1472			goto error;
1473		}
1474
1475		DMEMIT("%u %llu/%llu %llu %u/%lu %u ",
1476		       DM_CLONE_METADATA_BLOCK_SIZE,
1477		       (unsigned long long)(nr_metadata_blocks - nr_free_metadata_blocks),
1478		       (unsigned long long)nr_metadata_blocks,
1479		       (unsigned long long)clone->region_size,
1480		       dm_clone_nr_of_hydrated_regions(clone->cmd),
1481		       clone->nr_regions,
1482		       atomic_read(&clone->hydrations_in_flight));
1483
1484		emit_flags(clone, result, maxlen, &sz);
1485		emit_core_args(clone, result, maxlen, &sz);
1486
1487		switch (get_clone_mode(clone)) {
1488		case CM_WRITE:
1489			DMEMIT("rw");
1490			break;
1491		case CM_READ_ONLY:
1492			DMEMIT("ro");
1493			break;
1494		case CM_FAIL:
1495			DMEMIT("Fail");
1496		}
1497
1498		break;
1499
1500	case STATUSTYPE_TABLE:
1501		format_dev_t(buf, clone->metadata_dev->bdev->bd_dev);
1502		DMEMIT("%s ", buf);
1503
1504		format_dev_t(buf, clone->dest_dev->bdev->bd_dev);
1505		DMEMIT("%s ", buf);
1506
1507		format_dev_t(buf, clone->source_dev->bdev->bd_dev);
1508		DMEMIT("%s", buf);
1509
1510		for (i = 0; i < clone->nr_ctr_args; i++)
1511			DMEMIT(" %s", clone->ctr_args[i]);
 
 
 
 
 
1512	}
1513
1514	return;
1515
1516error:
1517	DMEMIT("Error");
1518}
1519
1520static sector_t get_dev_size(struct dm_dev *dev)
1521{
1522	return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
1523}
1524
1525/*---------------------------------------------------------------------------*/
1526
1527/*
1528 * Construct a clone device mapping:
1529 *
1530 * clone <metadata dev> <destination dev> <source dev> <region size>
1531 *	[<#feature args> [<feature arg>]* [<#core args> [key value]*]]
1532 *
1533 * metadata dev: Fast device holding the persistent metadata
1534 * destination dev: The destination device, which will become a clone of the
1535 *                  source device
1536 * source dev: The read-only source device that gets cloned
1537 * region size: dm-clone unit size in sectors
1538 *
1539 * #feature args: Number of feature arguments passed
1540 * feature args: E.g. no_hydration, no_discard_passdown
1541 *
1542 * #core arguments: An even number of core arguments
1543 * core arguments: Key/value pairs for tuning the core
1544 *		   E.g. 'hydration_threshold 256'
1545 */
1546static int parse_feature_args(struct dm_arg_set *as, struct clone *clone)
1547{
1548	int r;
1549	unsigned int argc;
1550	const char *arg_name;
1551	struct dm_target *ti = clone->ti;
1552
1553	const struct dm_arg args = {
1554		.min = 0,
1555		.max = 2,
1556		.error = "Invalid number of feature arguments"
1557	};
1558
1559	/* No feature arguments supplied */
1560	if (!as->argc)
1561		return 0;
1562
1563	r = dm_read_arg_group(&args, as, &argc, &ti->error);
1564	if (r)
1565		return r;
1566
1567	while (argc) {
1568		arg_name = dm_shift_arg(as);
1569		argc--;
1570
1571		if (!strcasecmp(arg_name, "no_hydration")) {
1572			__clear_bit(DM_CLONE_HYDRATION_ENABLED, &clone->flags);
1573		} else if (!strcasecmp(arg_name, "no_discard_passdown")) {
1574			__clear_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags);
1575		} else {
1576			ti->error = "Invalid feature argument";
1577			return -EINVAL;
1578		}
1579	}
1580
1581	return 0;
1582}
1583
1584static int parse_core_args(struct dm_arg_set *as, struct clone *clone)
1585{
1586	int r;
1587	unsigned int argc;
1588	unsigned int value;
1589	const char *arg_name;
1590	struct dm_target *ti = clone->ti;
1591
1592	const struct dm_arg args = {
1593		.min = 0,
1594		.max = 4,
1595		.error = "Invalid number of core arguments"
1596	};
1597
1598	/* Initialize core arguments */
1599	clone->hydration_batch_size = DEFAULT_HYDRATION_BATCH_SIZE;
1600	clone->hydration_threshold = DEFAULT_HYDRATION_THRESHOLD;
1601
1602	/* No core arguments supplied */
1603	if (!as->argc)
1604		return 0;
1605
1606	r = dm_read_arg_group(&args, as, &argc, &ti->error);
1607	if (r)
1608		return r;
1609
1610	if (argc & 1) {
1611		ti->error = "Number of core arguments must be even";
1612		return -EINVAL;
1613	}
1614
1615	while (argc) {
1616		arg_name = dm_shift_arg(as);
1617		argc -= 2;
1618
1619		if (!strcasecmp(arg_name, "hydration_threshold")) {
1620			if (kstrtouint(dm_shift_arg(as), 10, &value)) {
1621				ti->error = "Invalid value for argument `hydration_threshold'";
1622				return -EINVAL;
1623			}
1624			clone->hydration_threshold = value;
1625		} else if (!strcasecmp(arg_name, "hydration_batch_size")) {
1626			if (kstrtouint(dm_shift_arg(as), 10, &value)) {
1627				ti->error = "Invalid value for argument `hydration_batch_size'";
1628				return -EINVAL;
1629			}
1630			clone->hydration_batch_size = value;
1631		} else {
1632			ti->error = "Invalid core argument";
1633			return -EINVAL;
1634		}
1635	}
1636
1637	return 0;
1638}
1639
1640static int parse_region_size(struct clone *clone, struct dm_arg_set *as, char **error)
1641{
1642	int r;
1643	unsigned int region_size;
1644	struct dm_arg arg;
1645
1646	arg.min = MIN_REGION_SIZE;
1647	arg.max = MAX_REGION_SIZE;
1648	arg.error = "Invalid region size";
1649
1650	r = dm_read_arg(&arg, as, &region_size, error);
1651	if (r)
1652		return r;
1653
1654	/* Check region size is a power of 2 */
1655	if (!is_power_of_2(region_size)) {
1656		*error = "Region size is not a power of 2";
1657		return -EINVAL;
1658	}
1659
1660	/* Validate the region size against the device logical block size */
1661	if (region_size % (bdev_logical_block_size(clone->source_dev->bdev) >> 9) ||
1662	    region_size % (bdev_logical_block_size(clone->dest_dev->bdev) >> 9)) {
1663		*error = "Region size is not a multiple of device logical block size";
1664		return -EINVAL;
1665	}
1666
1667	clone->region_size = region_size;
1668
1669	return 0;
1670}
1671
1672static int validate_nr_regions(unsigned long n, char **error)
1673{
1674	/*
1675	 * dm_bitset restricts us to 2^32 regions. test_bit & co. restrict us
1676	 * further to 2^31 regions.
1677	 */
1678	if (n > (1UL << 31)) {
1679		*error = "Too many regions. Consider increasing the region size";
1680		return -EINVAL;
1681	}
1682
1683	return 0;
1684}
1685
1686static int parse_metadata_dev(struct clone *clone, struct dm_arg_set *as, char **error)
1687{
1688	int r;
1689	sector_t metadata_dev_size;
1690	char b[BDEVNAME_SIZE];
1691
1692	r = dm_get_device(clone->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1693			  &clone->metadata_dev);
1694	if (r) {
1695		*error = "Error opening metadata device";
1696		return r;
1697	}
1698
1699	metadata_dev_size = get_dev_size(clone->metadata_dev);
1700	if (metadata_dev_size > DM_CLONE_METADATA_MAX_SECTORS_WARNING)
1701		DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1702		       bdevname(clone->metadata_dev->bdev, b), DM_CLONE_METADATA_MAX_SECTORS);
1703
1704	return 0;
1705}
1706
1707static int parse_dest_dev(struct clone *clone, struct dm_arg_set *as, char **error)
1708{
1709	int r;
1710	sector_t dest_dev_size;
1711
1712	r = dm_get_device(clone->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
1713			  &clone->dest_dev);
1714	if (r) {
1715		*error = "Error opening destination device";
1716		return r;
1717	}
1718
1719	dest_dev_size = get_dev_size(clone->dest_dev);
1720	if (dest_dev_size < clone->ti->len) {
1721		dm_put_device(clone->ti, clone->dest_dev);
1722		*error = "Device size larger than destination device";
1723		return -EINVAL;
1724	}
1725
1726	return 0;
1727}
1728
1729static int parse_source_dev(struct clone *clone, struct dm_arg_set *as, char **error)
1730{
1731	int r;
1732	sector_t source_dev_size;
1733
1734	r = dm_get_device(clone->ti, dm_shift_arg(as), FMODE_READ,
1735			  &clone->source_dev);
1736	if (r) {
1737		*error = "Error opening source device";
1738		return r;
1739	}
1740
1741	source_dev_size = get_dev_size(clone->source_dev);
1742	if (source_dev_size < clone->ti->len) {
1743		dm_put_device(clone->ti, clone->source_dev);
1744		*error = "Device size larger than source device";
1745		return -EINVAL;
1746	}
1747
1748	return 0;
1749}
1750
1751static int copy_ctr_args(struct clone *clone, int argc, const char **argv, char **error)
1752{
1753	unsigned int i;
1754	const char **copy;
1755
1756	copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
1757	if (!copy)
1758		goto error;
1759
1760	for (i = 0; i < argc; i++) {
1761		copy[i] = kstrdup(argv[i], GFP_KERNEL);
1762
1763		if (!copy[i]) {
1764			while (i--)
1765				kfree(copy[i]);
1766			kfree(copy);
1767			goto error;
1768		}
1769	}
1770
1771	clone->nr_ctr_args = argc;
1772	clone->ctr_args = copy;
1773	return 0;
1774
1775error:
1776	*error = "Failed to allocate memory for table line";
1777	return -ENOMEM;
1778}
1779
1780static int clone_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1781{
1782	int r;
1783	sector_t nr_regions;
1784	struct clone *clone;
1785	struct dm_arg_set as;
1786
1787	if (argc < 4) {
1788		ti->error = "Invalid number of arguments";
1789		return -EINVAL;
1790	}
1791
1792	as.argc = argc;
1793	as.argv = argv;
1794
1795	clone = kzalloc(sizeof(*clone), GFP_KERNEL);
1796	if (!clone) {
1797		ti->error = "Failed to allocate clone structure";
1798		return -ENOMEM;
1799	}
1800
1801	clone->ti = ti;
1802
1803	/* Initialize dm-clone flags */
1804	__set_bit(DM_CLONE_HYDRATION_ENABLED, &clone->flags);
1805	__set_bit(DM_CLONE_HYDRATION_SUSPENDED, &clone->flags);
1806	__set_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags);
1807
1808	r = parse_metadata_dev(clone, &as, &ti->error);
1809	if (r)
1810		goto out_with_clone;
1811
1812	r = parse_dest_dev(clone, &as, &ti->error);
1813	if (r)
1814		goto out_with_meta_dev;
1815
1816	r = parse_source_dev(clone, &as, &ti->error);
1817	if (r)
1818		goto out_with_dest_dev;
1819
1820	r = parse_region_size(clone, &as, &ti->error);
1821	if (r)
1822		goto out_with_source_dev;
1823
1824	clone->region_shift = __ffs(clone->region_size);
1825	nr_regions = dm_sector_div_up(ti->len, clone->region_size);
1826
1827	/* Check for overflow */
1828	if (nr_regions != (unsigned long)nr_regions) {
1829		ti->error = "Too many regions. Consider increasing the region size";
1830		r = -EOVERFLOW;
1831		goto out_with_source_dev;
1832	}
1833
1834	clone->nr_regions = nr_regions;
1835
1836	r = validate_nr_regions(clone->nr_regions, &ti->error);
1837	if (r)
1838		goto out_with_source_dev;
1839
1840	r = dm_set_target_max_io_len(ti, clone->region_size);
1841	if (r) {
1842		ti->error = "Failed to set max io len";
1843		goto out_with_source_dev;
1844	}
1845
1846	r = parse_feature_args(&as, clone);
1847	if (r)
1848		goto out_with_source_dev;
1849
1850	r = parse_core_args(&as, clone);
1851	if (r)
1852		goto out_with_source_dev;
1853
1854	/* Load metadata */
1855	clone->cmd = dm_clone_metadata_open(clone->metadata_dev->bdev, ti->len,
1856					    clone->region_size);
1857	if (IS_ERR(clone->cmd)) {
1858		ti->error = "Failed to load metadata";
1859		r = PTR_ERR(clone->cmd);
1860		goto out_with_source_dev;
1861	}
1862
1863	__set_clone_mode(clone, CM_WRITE);
1864
1865	if (get_clone_mode(clone) != CM_WRITE) {
1866		ti->error = "Unable to get write access to metadata, please check/repair metadata";
1867		r = -EPERM;
1868		goto out_with_metadata;
1869	}
1870
1871	clone->last_commit_jiffies = jiffies;
1872
1873	/* Allocate hydration hash table */
1874	r = hash_table_init(clone);
1875	if (r) {
1876		ti->error = "Failed to allocate hydration hash table";
1877		goto out_with_metadata;
1878	}
1879
1880	atomic_set(&clone->ios_in_flight, 0);
1881	init_waitqueue_head(&clone->hydration_stopped);
1882	spin_lock_init(&clone->lock);
1883	bio_list_init(&clone->deferred_bios);
1884	bio_list_init(&clone->deferred_discard_bios);
1885	bio_list_init(&clone->deferred_flush_bios);
1886	bio_list_init(&clone->deferred_flush_completions);
1887	clone->hydration_offset = 0;
1888	atomic_set(&clone->hydrations_in_flight, 0);
1889	bio_init(&clone->flush_bio, NULL, 0);
1890
1891	clone->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
1892	if (!clone->wq) {
1893		ti->error = "Failed to allocate workqueue";
1894		r = -ENOMEM;
1895		goto out_with_ht;
1896	}
1897
1898	INIT_WORK(&clone->worker, do_worker);
1899	INIT_DELAYED_WORK(&clone->waker, do_waker);
1900
1901	clone->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle);
1902	if (IS_ERR(clone->kcopyd_client)) {
1903		r = PTR_ERR(clone->kcopyd_client);
1904		goto out_with_wq;
1905	}
1906
1907	r = mempool_init_slab_pool(&clone->hydration_pool, MIN_HYDRATIONS,
1908				   _hydration_cache);
1909	if (r) {
1910		ti->error = "Failed to create dm_clone_region_hydration memory pool";
1911		goto out_with_kcopyd;
1912	}
1913
1914	/* Save a copy of the table line */
1915	r = copy_ctr_args(clone, argc - 3, (const char **)argv + 3, &ti->error);
1916	if (r)
1917		goto out_with_mempool;
1918
1919	mutex_init(&clone->commit_lock);
1920
1921	/* Enable flushes */
1922	ti->num_flush_bios = 1;
1923	ti->flush_supported = true;
1924
1925	/* Enable discards */
1926	ti->discards_supported = true;
1927	ti->num_discard_bios = 1;
1928
1929	ti->private = clone;
1930
1931	return 0;
1932
1933out_with_mempool:
1934	mempool_exit(&clone->hydration_pool);
1935out_with_kcopyd:
1936	dm_kcopyd_client_destroy(clone->kcopyd_client);
1937out_with_wq:
1938	destroy_workqueue(clone->wq);
1939out_with_ht:
1940	hash_table_exit(clone);
1941out_with_metadata:
1942	dm_clone_metadata_close(clone->cmd);
1943out_with_source_dev:
1944	dm_put_device(ti, clone->source_dev);
1945out_with_dest_dev:
1946	dm_put_device(ti, clone->dest_dev);
1947out_with_meta_dev:
1948	dm_put_device(ti, clone->metadata_dev);
1949out_with_clone:
1950	kfree(clone);
1951
1952	return r;
1953}
1954
1955static void clone_dtr(struct dm_target *ti)
1956{
1957	unsigned int i;
1958	struct clone *clone = ti->private;
1959
1960	mutex_destroy(&clone->commit_lock);
1961	bio_uninit(&clone->flush_bio);
1962
1963	for (i = 0; i < clone->nr_ctr_args; i++)
1964		kfree(clone->ctr_args[i]);
1965	kfree(clone->ctr_args);
1966
1967	mempool_exit(&clone->hydration_pool);
1968	dm_kcopyd_client_destroy(clone->kcopyd_client);
 
1969	destroy_workqueue(clone->wq);
1970	hash_table_exit(clone);
1971	dm_clone_metadata_close(clone->cmd);
1972	dm_put_device(ti, clone->source_dev);
1973	dm_put_device(ti, clone->dest_dev);
1974	dm_put_device(ti, clone->metadata_dev);
1975
1976	kfree(clone);
1977}
1978
1979/*---------------------------------------------------------------------------*/
1980
1981static void clone_postsuspend(struct dm_target *ti)
1982{
1983	struct clone *clone = ti->private;
1984
1985	/*
1986	 * To successfully suspend the device:
1987	 *
1988	 *	- We cancel the delayed work for periodic commits and wait for
1989	 *	  it to finish.
1990	 *
1991	 *	- We stop the background hydration, i.e. we prevent new region
1992	 *	  hydrations from starting.
1993	 *
1994	 *	- We wait for any in-flight hydrations to finish.
1995	 *
1996	 *	- We flush the workqueue.
1997	 *
1998	 *	- We commit the metadata.
1999	 */
2000	cancel_delayed_work_sync(&clone->waker);
2001
2002	set_bit(DM_CLONE_HYDRATION_SUSPENDED, &clone->flags);
2003
2004	/*
2005	 * Make sure set_bit() is ordered before atomic_read(), otherwise we
2006	 * might race with do_hydration() and miss some started region
2007	 * hydrations.
2008	 *
2009	 * This is paired with smp_mb__after_atomic() in do_hydration().
2010	 */
2011	smp_mb__after_atomic();
2012
2013	wait_event(clone->hydration_stopped, !atomic_read(&clone->hydrations_in_flight));
2014	flush_workqueue(clone->wq);
2015
2016	(void) commit_metadata(clone, NULL);
2017}
2018
2019static void clone_resume(struct dm_target *ti)
2020{
2021	struct clone *clone = ti->private;
2022
2023	clear_bit(DM_CLONE_HYDRATION_SUSPENDED, &clone->flags);
2024	do_waker(&clone->waker.work);
2025}
2026
2027static bool bdev_supports_discards(struct block_device *bdev)
2028{
2029	struct request_queue *q = bdev_get_queue(bdev);
2030
2031	return (q && blk_queue_discard(q));
2032}
2033
2034/*
2035 * If discard_passdown was enabled verify that the destination device supports
2036 * discards. Disable discard_passdown if not.
2037 */
2038static void disable_passdown_if_not_supported(struct clone *clone)
2039{
2040	struct block_device *dest_dev = clone->dest_dev->bdev;
2041	struct queue_limits *dest_limits = &bdev_get_queue(dest_dev)->limits;
2042	const char *reason = NULL;
2043	char buf[BDEVNAME_SIZE];
2044
2045	if (!test_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags))
2046		return;
2047
2048	if (!bdev_supports_discards(dest_dev))
2049		reason = "discard unsupported";
2050	else if (dest_limits->max_discard_sectors < clone->region_size)
2051		reason = "max discard sectors smaller than a region";
2052
2053	if (reason) {
2054		DMWARN("Destination device (%s) %s: Disabling discard passdown.",
2055		       bdevname(dest_dev, buf), reason);
2056		clear_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags);
2057	}
2058}
2059
2060static void set_discard_limits(struct clone *clone, struct queue_limits *limits)
2061{
2062	struct block_device *dest_bdev = clone->dest_dev->bdev;
2063	struct queue_limits *dest_limits = &bdev_get_queue(dest_bdev)->limits;
2064
2065	if (!test_bit(DM_CLONE_DISCARD_PASSDOWN, &clone->flags)) {
2066		/* No passdown is done so we set our own virtual limits */
2067		limits->discard_granularity = clone->region_size << SECTOR_SHIFT;
2068		limits->max_discard_sectors = round_down(UINT_MAX >> SECTOR_SHIFT, clone->region_size);
2069		return;
2070	}
2071
2072	/*
2073	 * clone_iterate_devices() is stacking both the source and destination
2074	 * device limits but discards aren't passed to the source device, so
2075	 * inherit destination's limits.
2076	 */
2077	limits->max_discard_sectors = dest_limits->max_discard_sectors;
2078	limits->max_hw_discard_sectors = dest_limits->max_hw_discard_sectors;
2079	limits->discard_granularity = dest_limits->discard_granularity;
2080	limits->discard_alignment = dest_limits->discard_alignment;
2081	limits->discard_misaligned = dest_limits->discard_misaligned;
2082	limits->max_discard_segments = dest_limits->max_discard_segments;
2083}
2084
2085static void clone_io_hints(struct dm_target *ti, struct queue_limits *limits)
2086{
2087	struct clone *clone = ti->private;
2088	u64 io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
2089
2090	/*
2091	 * If the system-determined stacked limits are compatible with
2092	 * dm-clone's region size (io_opt is a factor) do not override them.
2093	 */
2094	if (io_opt_sectors < clone->region_size ||
2095	    do_div(io_opt_sectors, clone->region_size)) {
2096		blk_limits_io_min(limits, clone->region_size << SECTOR_SHIFT);
2097		blk_limits_io_opt(limits, clone->region_size << SECTOR_SHIFT);
2098	}
2099
2100	disable_passdown_if_not_supported(clone);
2101	set_discard_limits(clone, limits);
2102}
2103
2104static int clone_iterate_devices(struct dm_target *ti,
2105				 iterate_devices_callout_fn fn, void *data)
2106{
2107	int ret;
2108	struct clone *clone = ti->private;
2109	struct dm_dev *dest_dev = clone->dest_dev;
2110	struct dm_dev *source_dev = clone->source_dev;
2111
2112	ret = fn(ti, source_dev, 0, ti->len, data);
2113	if (!ret)
2114		ret = fn(ti, dest_dev, 0, ti->len, data);
2115	return ret;
2116}
2117
2118/*
2119 * dm-clone message functions.
2120 */
2121static void set_hydration_threshold(struct clone *clone, unsigned int nr_regions)
2122{
2123	WRITE_ONCE(clone->hydration_threshold, nr_regions);
2124
2125	/*
2126	 * If user space sets hydration_threshold to zero then the hydration
2127	 * will stop. If at a later time the hydration_threshold is increased
2128	 * we must restart the hydration process by waking up the worker.
2129	 */
2130	wake_worker(clone);
2131}
2132
2133static void set_hydration_batch_size(struct clone *clone, unsigned int nr_regions)
2134{
2135	WRITE_ONCE(clone->hydration_batch_size, nr_regions);
2136}
2137
2138static void enable_hydration(struct clone *clone)
2139{
2140	if (!test_and_set_bit(DM_CLONE_HYDRATION_ENABLED, &clone->flags))
2141		wake_worker(clone);
2142}
2143
2144static void disable_hydration(struct clone *clone)
2145{
2146	clear_bit(DM_CLONE_HYDRATION_ENABLED, &clone->flags);
2147}
2148
2149static int clone_message(struct dm_target *ti, unsigned int argc, char **argv,
2150			 char *result, unsigned int maxlen)
2151{
2152	struct clone *clone = ti->private;
2153	unsigned int value;
2154
2155	if (!argc)
2156		return -EINVAL;
2157
2158	if (!strcasecmp(argv[0], "enable_hydration")) {
2159		enable_hydration(clone);
2160		return 0;
2161	}
2162
2163	if (!strcasecmp(argv[0], "disable_hydration")) {
2164		disable_hydration(clone);
2165		return 0;
2166	}
2167
2168	if (argc != 2)
2169		return -EINVAL;
2170
2171	if (!strcasecmp(argv[0], "hydration_threshold")) {
2172		if (kstrtouint(argv[1], 10, &value))
2173			return -EINVAL;
2174
2175		set_hydration_threshold(clone, value);
2176
2177		return 0;
2178	}
2179
2180	if (!strcasecmp(argv[0], "hydration_batch_size")) {
2181		if (kstrtouint(argv[1], 10, &value))
2182			return -EINVAL;
2183
2184		set_hydration_batch_size(clone, value);
2185
2186		return 0;
2187	}
2188
2189	DMERR("%s: Unsupported message `%s'", clone_device_name(clone), argv[0]);
2190	return -EINVAL;
2191}
2192
2193static struct target_type clone_target = {
2194	.name = "clone",
2195	.version = {1, 0, 0},
2196	.module = THIS_MODULE,
2197	.ctr = clone_ctr,
2198	.dtr =  clone_dtr,
2199	.map = clone_map,
2200	.end_io = clone_endio,
2201	.postsuspend = clone_postsuspend,
2202	.resume = clone_resume,
2203	.status = clone_status,
2204	.message = clone_message,
2205	.io_hints = clone_io_hints,
2206	.iterate_devices = clone_iterate_devices,
2207};
2208
2209/*---------------------------------------------------------------------------*/
2210
2211/* Module functions */
2212static int __init dm_clone_init(void)
2213{
2214	int r;
2215
2216	_hydration_cache = KMEM_CACHE(dm_clone_region_hydration, 0);
2217	if (!_hydration_cache)
2218		return -ENOMEM;
2219
2220	r = dm_register_target(&clone_target);
2221	if (r < 0) {
2222		DMERR("Failed to register clone target");
2223		return r;
2224	}
2225
2226	return 0;
2227}
2228
2229static void __exit dm_clone_exit(void)
2230{
2231	dm_unregister_target(&clone_target);
2232
2233	kmem_cache_destroy(_hydration_cache);
2234	_hydration_cache = NULL;
2235}
2236
2237/* Module hooks */
2238module_init(dm_clone_init);
2239module_exit(dm_clone_exit);
2240
2241MODULE_DESCRIPTION(DM_NAME " clone target");
2242MODULE_AUTHOR("Nikos Tsironis <ntsironis@arrikto.com>");
2243MODULE_LICENSE("GPL");