dm-thin.c 107 KB
Newer Older
1
/*
2
 * Copyright (C) 2011-2012 Red Hat UK.
3
4
5
6
7
 *
 * This file is released under the GPL.
 */

#include "dm-thin-metadata.h"
8
#include "dm-bio-prison.h"
9
#include "dm.h"
10
11
12
13

#include <linux/device-mapper.h>
#include <linux/dm-io.h>
#include <linux/dm-kcopyd.h>
14
#include <linux/jiffies.h>
15
#include <linux/log2.h>
16
#include <linux/list.h>
17
#include <linux/rculist.h>
18
19
20
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
21
#include <linux/vmalloc.h>
22
#include <linux/sort.h>
23
#include <linux/rbtree.h>
24
25
26
27
28
29

#define	DM_MSG_PREFIX	"thin"

/*
 * Tunable constants
 */
30
#define ENDIO_HOOK_POOL_SIZE 1024
31
#define MAPPING_POOL_SIZE 1024
32
#define COMMIT_PERIOD HZ
33
34
35
#define NO_SPACE_TIMEOUT_SECS 60

static unsigned no_space_timeout_secs = NO_SPACE_TIMEOUT_SECS;
36

37
38
39
DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle,
		"A percentage of time allocated for copy on write");

40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
/*
 * The block size of the device holding pool data must be
 * between 64KB and 1GB.
 */
#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (64 * 1024 >> SECTOR_SHIFT)
#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)

/*
 * Device id is restricted to 24 bits.
 */
#define MAX_DEV_ID ((1 << 24) - 1)

/*
 * How do we handle breaking sharing of data blocks?
 * =================================================
 *
 * We use a standard copy-on-write btree to store the mappings for the
 * devices (note I'm talking about copy-on-write of the metadata here, not
 * the data).  When you take an internal snapshot you clone the root node
 * of the origin btree.  After this there is no concept of an origin or a
 * snapshot.  They are just two device trees that happen to point to the
 * same data blocks.
 *
 * When we get a write in we decide if it's to a shared data block using
 * some timestamp magic.  If it is, we have to break sharing.
 *
 * Let's say we write to a shared block in what was the origin.  The
 * steps are:
 *
 * i) plug io further to this physical block. (see bio_prison code).
 *
 * ii) quiesce any read io to that shared data block.  Obviously
72
 * including all devices that share this block.  (see dm_deferred_set code)
73
74
75
76
77
 *
 * iii) copy the data block to a newly allocate block.  This step can be
 * missed out if the io covers the block. (schedule_copy).
 *
 * iv) insert the new mapping into the origin's btree
Joe Thornber's avatar
Joe Thornber committed
78
 * (process_prepared_mapping).  This act of inserting breaks some
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
 * sharing of btree nodes between the two devices.  Breaking sharing only
 * effects the btree of that specific device.  Btrees for the other
 * devices that share the block never change.  The btree for the origin
 * device as it was after the last commit is untouched, ie. we're using
 * persistent data structures in the functional programming sense.
 *
 * v) unplug io to this physical block, including the io that triggered
 * the breaking of sharing.
 *
 * Steps (ii) and (iii) occur in parallel.
 *
 * The metadata _doesn't_ need to be committed before the io continues.  We
 * get away with this because the io is always written to a _new_ block.
 * If there's a crash, then:
 *
 * - The origin mapping will point to the old origin block (the shared
 * one).  This will contain the data as it was before the io that triggered
 * the breaking of sharing came in.
 *
 * - The snap mapping still points to the old block.  As it would after
 * the commit.
 *
 * The downside of this scheme is the timestamp magic isn't perfect, and
 * will continue to think that data block in the snapshot device is shared
 * even after the write to the origin has broken sharing.  I suspect data
 * blocks will typically be shared by many different devices, so we're
 * breaking sharing n + 1 times, rather than n, where n is the number of
 * devices that reference this data block.  At the moment I think the
 * benefits far, far outweigh the disadvantages.
 */

/*----------------------------------------------------------------*/

/*
 * Key building.
 */
Joe Thornber's avatar
Joe Thornber committed
115
116
117
118
119
120
121
enum lock_space {
	VIRTUAL,
	PHYSICAL
};

static void build_key(struct dm_thin_device *td, enum lock_space ls,
		      dm_block_t b, dm_block_t e, struct dm_cell_key *key)
122
{
Joe Thornber's avatar
Joe Thornber committed
123
	key->virtual = (ls == VIRTUAL);
124
	key->dev = dm_thin_dev_id(td);
125
	key->block_begin = b;
Joe Thornber's avatar
Joe Thornber committed
126
127
128
129
130
131
132
	key->block_end = e;
}

static void build_data_key(struct dm_thin_device *td, dm_block_t b,
			   struct dm_cell_key *key)
{
	build_key(td, PHYSICAL, b, b + 1llu, key);
133
134
135
}

static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
136
			      struct dm_cell_key *key)
137
{
Joe Thornber's avatar
Joe Thornber committed
138
	build_key(td, VIRTUAL, b, b + 1llu, key);
139
140
141
142
}

/*----------------------------------------------------------------*/

Joe Thornber's avatar
Joe Thornber committed
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
#define THROTTLE_THRESHOLD (1 * HZ)

struct throttle {
	struct rw_semaphore lock;
	unsigned long threshold;
	bool throttle_applied;
};

static void throttle_init(struct throttle *t)
{
	init_rwsem(&t->lock);
	t->throttle_applied = false;
}

static void throttle_work_start(struct throttle *t)
{
	t->threshold = jiffies + THROTTLE_THRESHOLD;
}

static void throttle_work_update(struct throttle *t)
{
	if (!t->throttle_applied && jiffies > t->threshold) {
		down_write(&t->lock);
		t->throttle_applied = true;
	}
}

static void throttle_work_complete(struct throttle *t)
{
	if (t->throttle_applied) {
		t->throttle_applied = false;
		up_write(&t->lock);
	}
}

static void throttle_lock(struct throttle *t)
{
	down_read(&t->lock);
}

static void throttle_unlock(struct throttle *t)
{
	up_read(&t->lock);
}

/*----------------------------------------------------------------*/

190
191
192
193
194
/*
 * A pool device ties together a metadata device and a data device.  It
 * also provides the interface for creating and destroying internal
 * devices.
 */
Mike Snitzer's avatar
Mike Snitzer committed
195
struct dm_thin_new_mapping;
196

197
/*
198
 * The pool runs in 4 modes.  Ordered in degraded order for comparisons.
199
200
201
 */
enum pool_mode {
	PM_WRITE,		/* metadata may be changed */
202
	PM_OUT_OF_DATA_SPACE,	/* metadata may be changed, though data may not be allocated */
203
204
205
206
	PM_READ_ONLY,		/* metadata may not be changed */
	PM_FAIL,		/* all I/O fails */
};

207
struct pool_features {
208
209
	enum pool_mode mode;

Mike Snitzer's avatar
Mike Snitzer committed
210
211
212
	bool zero_new_blocks:1;
	bool discard_enabled:1;
	bool discard_passdown:1;
213
	bool error_if_no_space:1;
214
215
};

216
217
struct thin_c;
typedef void (*process_bio_fn)(struct thin_c *tc, struct bio *bio);
218
typedef void (*process_cell_fn)(struct thin_c *tc, struct dm_bio_prison_cell *cell);
219
220
typedef void (*process_mapping_fn)(struct dm_thin_new_mapping *m);

221
222
#define CELL_SORT_ARRAY_SIZE 8192

223
224
225
226
227
228
229
230
231
struct pool {
	struct list_head list;
	struct dm_target *ti;	/* Only set if a pool target is bound */

	struct mapped_device *pool_md;
	struct block_device *md_dev;
	struct dm_pool_metadata *pmd;

	dm_block_t low_water_blocks;
232
	uint32_t sectors_per_block;
233
	int sectors_per_block_shift;
234

235
	struct pool_features pf;
236
	bool low_water_triggered:1;	/* A dm event has been sent */
237
	bool suspended:1;
238
	bool out_of_data_space:1;
239

240
	struct dm_bio_prison *prison;
241
242
243
	struct dm_kcopyd_client *copier;

	struct workqueue_struct *wq;
Joe Thornber's avatar
Joe Thornber committed
244
	struct throttle throttle;
245
	struct work_struct worker;
246
	struct delayed_work waker;
247
	struct delayed_work no_space_timeout;
248

249
	unsigned long last_commit_jiffies;
250
	unsigned ref_count;
251
252
253
254

	spinlock_t lock;
	struct bio_list deferred_flush_bios;
	struct list_head prepared_mappings;
Joe Thornber's avatar
Joe Thornber committed
255
	struct list_head prepared_discards;
256
	struct list_head active_thins;
257

258
259
	struct dm_deferred_set *shared_read_ds;
	struct dm_deferred_set *all_io_ds;
260

Mike Snitzer's avatar
Mike Snitzer committed
261
	struct dm_thin_new_mapping *next_mapping;
262
	mempool_t *mapping_pool;
263
264
265
266

	process_bio_fn process_bio;
	process_bio_fn process_discard;

267
268
269
	process_cell_fn process_cell;
	process_cell_fn process_discard_cell;

270
271
	process_mapping_fn process_prepared_mapping;
	process_mapping_fn process_prepared_discard;
272

273
	struct dm_bio_prison_cell **cell_sort_array;
274
275
};

276
static enum pool_mode get_pool_mode(struct pool *pool);
277
static void metadata_operation_failed(struct pool *pool, const char *op, int r);
278

279
280
281
282
283
284
285
286
287
288
289
/*
 * Target context for a pool.
 */
struct pool_c {
	struct dm_target *ti;
	struct pool *pool;
	struct dm_dev *data_dev;
	struct dm_dev *metadata_dev;
	struct dm_target_callbacks callbacks;

	dm_block_t low_water_blocks;
290
291
	struct pool_features requested_pf; /* Features requested during table load */
	struct pool_features adjusted_pf;  /* Features used after adjusting for constituent devices */
292
293
294
295
296
297
};

/*
 * Target context for a thin.
 */
struct thin_c {
298
	struct list_head list;
299
	struct dm_dev *pool_dev;
300
	struct dm_dev *origin_dev;
301
	sector_t origin_size;
302
303
304
305
	dm_thin_id dev_id;

	struct pool *pool;
	struct dm_thin_device *td;
306
307
	struct mapped_device *thin_md;

308
	bool requeue_mode:1;
309
	spinlock_t lock;
310
	struct list_head deferred_cells;
311
312
	struct bio_list deferred_bio_list;
	struct bio_list retry_on_resume_list;
313
	struct rb_root sort_bio_list; /* sorted list of deferred bios */
314
315
316
317
318
319
320

	/*
	 * Ensures the thin is not destroyed until the worker has finished
	 * iterating the active_thins list.
	 */
	atomic_t refcount;
	struct completion can_destroy;
321
322
323
324
};

/*----------------------------------------------------------------*/

Joe Thornber's avatar
Joe Thornber committed
325
326
327
328
329
330
331
332
333
334
335
336
static bool block_size_is_power_of_two(struct pool *pool)
{
	return pool->sectors_per_block_shift >= 0;
}

static sector_t block_to_sectors(struct pool *pool, dm_block_t b)
{
	return block_size_is_power_of_two(pool) ?
		(b << pool->sectors_per_block_shift) :
		(b * pool->sectors_per_block);
}

337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
/*----------------------------------------------------------------*/

struct discard_op {
	struct thin_c *tc;
	struct blk_plug plug;
	struct bio *parent_bio;
	struct bio *bio;
};

static void begin_discard(struct discard_op *op, struct thin_c *tc, struct bio *parent)
{
	BUG_ON(!parent);

	op->tc = tc;
	blk_start_plug(&op->plug);
	op->parent_bio = parent;
	op->bio = NULL;
}

static int issue_discard(struct discard_op *op, dm_block_t data_b, dm_block_t data_e)
Joe Thornber's avatar
Joe Thornber committed
357
{
358
	struct thin_c *tc = op->tc;
Joe Thornber's avatar
Joe Thornber committed
359
360
	sector_t s = block_to_sectors(tc->pool, data_b);
	sector_t len = block_to_sectors(tc->pool, data_e - data_b);
361

362
363
364
365
366
367
368
369
370
371
372
373
	return __blkdev_issue_discard(tc->pool_dev->bdev, s, len,
				      GFP_NOWAIT, REQ_WRITE | REQ_DISCARD, &op->bio);
}

static void end_discard(struct discard_op *op, int r)
{
	if (op->bio) {
		/*
		 * Even if one of the calls to issue_discard failed, we
		 * need to wait for the chain to complete.
		 */
		bio_chain(op->bio, op->parent_bio);
374
375
		op->bio->bi_rw = REQ_WRITE | REQ_DISCARD;
		submit_bio(op->bio);
376
	}
Joe Thornber's avatar
Joe Thornber committed
377

378
379
380
381
382
383
384
385
386
	blk_finish_plug(&op->plug);

	/*
	 * Even if r is set, there could be sub discards in flight that we
	 * need to wait for.
	 */
	if (r && !op->parent_bio->bi_error)
		op->parent_bio->bi_error = r;
	bio_endio(op->parent_bio);
Joe Thornber's avatar
Joe Thornber committed
387
388
389
390
}

/*----------------------------------------------------------------*/

391
392
393
394
395
396
397
398
399
400
401
/*
 * wake_worker() is used when new work is queued and when pool_resume is
 * ready to continue deferred IO processing.
 */
static void wake_worker(struct pool *pool)
{
	queue_work(pool->wq, &pool->worker);
}

/*----------------------------------------------------------------*/

402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
static int bio_detain(struct pool *pool, struct dm_cell_key *key, struct bio *bio,
		      struct dm_bio_prison_cell **cell_result)
{
	int r;
	struct dm_bio_prison_cell *cell_prealloc;

	/*
	 * Allocate a cell from the prison's mempool.
	 * This might block but it can't fail.
	 */
	cell_prealloc = dm_bio_prison_alloc_cell(pool->prison, GFP_NOIO);

	r = dm_bio_detain(pool->prison, key, bio, cell_prealloc, cell_result);
	if (r)
		/*
		 * We reused an old cell; we can get rid of
		 * the new one.
		 */
		dm_bio_prison_free_cell(pool->prison, cell_prealloc);

	return r;
}

static void cell_release(struct pool *pool,
			 struct dm_bio_prison_cell *cell,
			 struct bio_list *bios)
{
	dm_cell_release(pool->prison, cell, bios);
	dm_bio_prison_free_cell(pool->prison, cell);
}

433
434
435
436
437
438
439
440
441
static void cell_visit_release(struct pool *pool,
			       void (*fn)(void *, struct dm_bio_prison_cell *),
			       void *context,
			       struct dm_bio_prison_cell *cell)
{
	dm_cell_visit_release(pool->prison, fn, context, cell);
	dm_bio_prison_free_cell(pool->prison, cell);
}

442
443
444
445
446
447
448
449
static void cell_release_no_holder(struct pool *pool,
				   struct dm_bio_prison_cell *cell,
				   struct bio_list *bios)
{
	dm_cell_release_no_holder(pool->prison, cell, bios);
	dm_bio_prison_free_cell(pool->prison, cell);
}

450
451
static void cell_error_with_code(struct pool *pool,
				 struct dm_bio_prison_cell *cell, int error_code)
452
{
453
	dm_cell_error(pool->prison, cell, error_code);
454
455
456
	dm_bio_prison_free_cell(pool->prison, cell);
}

457
458
459
460
461
static int get_pool_io_error_code(struct pool *pool)
{
	return pool->out_of_data_space ? -ENOSPC : -EIO;
}

462
463
static void cell_error(struct pool *pool, struct dm_bio_prison_cell *cell)
{
464
465
466
	int error = get_pool_io_error_code(pool);

	cell_error_with_code(pool, cell, error);
467
468
}

469
470
471
472
473
474
475
476
477
478
static void cell_success(struct pool *pool, struct dm_bio_prison_cell *cell)
{
	cell_error_with_code(pool, cell, 0);
}

static void cell_requeue(struct pool *pool, struct dm_bio_prison_cell *cell)
{
	cell_error_with_code(pool, cell, DM_ENDIO_REQUEUE);
}

479
480
/*----------------------------------------------------------------*/

481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
/*
 * A global list of pools that uses a struct mapped_device as a key.
 */
static struct dm_thin_pool_table {
	struct mutex mutex;
	struct list_head pools;
} dm_thin_pool_table;

static void pool_table_init(void)
{
	mutex_init(&dm_thin_pool_table.mutex);
	INIT_LIST_HEAD(&dm_thin_pool_table.pools);
}

static void __pool_table_insert(struct pool *pool)
{
	BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
	list_add(&pool->list, &dm_thin_pool_table.pools);
}

static void __pool_table_remove(struct pool *pool)
{
	BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
	list_del(&pool->list);
}

static struct pool *__pool_table_lookup(struct mapped_device *md)
{
	struct pool *pool = NULL, *tmp;

	BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));

	list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) {
		if (tmp->pool_md == md) {
			pool = tmp;
			break;
		}
	}

	return pool;
}

static struct pool *__pool_table_lookup_metadata_dev(struct block_device *md_dev)
{
	struct pool *pool = NULL, *tmp;

	BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));

	list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) {
		if (tmp->md_dev == md_dev) {
			pool = tmp;
			break;
		}
	}

	return pool;
}

/*----------------------------------------------------------------*/

Mike Snitzer's avatar
Mike Snitzer committed
541
struct dm_thin_endio_hook {
542
	struct thin_c *tc;
543
544
	struct dm_deferred_entry *shared_read_entry;
	struct dm_deferred_entry *all_io_entry;
Mike Snitzer's avatar
Mike Snitzer committed
545
	struct dm_thin_new_mapping *overwrite_mapping;
546
	struct rb_node rb_node;
Joe Thornber's avatar
Joe Thornber committed
547
	struct dm_bio_prison_cell *cell;
548
549
};

550
551
552
553
554
555
556
static void __merge_bio_list(struct bio_list *bios, struct bio_list *master)
{
	bio_list_merge(bios, master);
	bio_list_init(master);
}

static void error_bio_list(struct bio_list *bios, int error)
557
558
{
	struct bio *bio;
559

560
561
562
563
	while ((bio = bio_list_pop(bios))) {
		bio->bi_error = error;
		bio_endio(bio);
	}
564
565
566
567
}

static void error_thin_bio_list(struct thin_c *tc, struct bio_list *master, int error)
{
568
	struct bio_list bios;
569
	unsigned long flags;
570
571

	bio_list_init(&bios);
572

573
	spin_lock_irqsave(&tc->lock, flags);
574
	__merge_bio_list(&bios, master);
575
	spin_unlock_irqrestore(&tc->lock, flags);
576

577
	error_bio_list(&bios, error);
578
579
}

580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
static void requeue_deferred_cells(struct thin_c *tc)
{
	struct pool *pool = tc->pool;
	unsigned long flags;
	struct list_head cells;
	struct dm_bio_prison_cell *cell, *tmp;

	INIT_LIST_HEAD(&cells);

	spin_lock_irqsave(&tc->lock, flags);
	list_splice_init(&tc->deferred_cells, &cells);
	spin_unlock_irqrestore(&tc->lock, flags);

	list_for_each_entry_safe(cell, tmp, &cells, user_list)
		cell_requeue(pool, cell);
}

597
598
static void requeue_io(struct thin_c *tc)
{
599
	struct bio_list bios;
600
	unsigned long flags;
601
602
603

	bio_list_init(&bios);

604
	spin_lock_irqsave(&tc->lock, flags);
605
606
	__merge_bio_list(&bios, &tc->deferred_bio_list);
	__merge_bio_list(&bios, &tc->retry_on_resume_list);
607
	spin_unlock_irqrestore(&tc->lock, flags);
608

609
610
	error_bio_list(&bios, DM_ENDIO_REQUEUE);
	requeue_deferred_cells(tc);
611
612
}

613
static void error_retry_list_with_code(struct pool *pool, int error)
614
615
616
617
618
{
	struct thin_c *tc;

	rcu_read_lock();
	list_for_each_entry_rcu(tc, &pool->active_thins, list)
619
		error_thin_bio_list(tc, &tc->retry_on_resume_list, error);
620
621
622
	rcu_read_unlock();
}

623
624
static void error_retry_list(struct pool *pool)
{
625
626
	int error = get_pool_io_error_code(pool);

627
	error_retry_list_with_code(pool, error);
628
629
}

630
631
632
633
634
635
636
637
638
/*
 * This section of code contains the logic for processing a thin device's IO.
 * Much of the code depends on pool object resources (lists, workqueues, etc)
 * but most is exclusively called from the thin target rather than the thin-pool
 * target.
 */

static dm_block_t get_bio_block(struct thin_c *tc, struct bio *bio)
{
639
	struct pool *pool = tc->pool;
640
	sector_t block_nr = bio->bi_iter.bi_sector;
641

642
643
	if (block_size_is_power_of_two(pool))
		block_nr >>= pool->sectors_per_block_shift;
644
	else
645
		(void) sector_div(block_nr, pool->sectors_per_block);
646
647

	return block_nr;
648
649
}

Joe Thornber's avatar
Joe Thornber committed
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
/*
 * Returns the _complete_ blocks that this bio covers.
 */
static void get_bio_block_range(struct thin_c *tc, struct bio *bio,
				dm_block_t *begin, dm_block_t *end)
{
	struct pool *pool = tc->pool;
	sector_t b = bio->bi_iter.bi_sector;
	sector_t e = b + (bio->bi_iter.bi_size >> SECTOR_SHIFT);

	b += pool->sectors_per_block - 1ull; /* so we round up */

	if (block_size_is_power_of_two(pool)) {
		b >>= pool->sectors_per_block_shift;
		e >>= pool->sectors_per_block_shift;
	} else {
		(void) sector_div(b, pool->sectors_per_block);
		(void) sector_div(e, pool->sectors_per_block);
	}

	if (e < b)
		/* Can happen if the bio is within a single block. */
		e = b;

	*begin = b;
	*end = e;
}

678
679
680
static void remap(struct thin_c *tc, struct bio *bio, dm_block_t block)
{
	struct pool *pool = tc->pool;
681
	sector_t bi_sector = bio->bi_iter.bi_sector;
682
683

	bio->bi_bdev = tc->pool_dev->bdev;
684
	if (block_size_is_power_of_two(pool))
685
686
687
		bio->bi_iter.bi_sector =
			(block << pool->sectors_per_block_shift) |
			(bi_sector & (pool->sectors_per_block - 1));
688
	else
689
		bio->bi_iter.bi_sector = (block * pool->sectors_per_block) +
690
				 sector_div(bi_sector, pool->sectors_per_block);
691
692
}

693
694
695
696
697
static void remap_to_origin(struct thin_c *tc, struct bio *bio)
{
	bio->bi_bdev = tc->origin_dev->bdev;
}

698
699
700
701
702
703
static int bio_triggers_commit(struct thin_c *tc, struct bio *bio)
{
	return (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) &&
		dm_thin_changed_this_transaction(tc->td);
}

704
705
706
707
708
709
710
static void inc_all_io_entry(struct pool *pool, struct bio *bio)
{
	struct dm_thin_endio_hook *h;

	if (bio->bi_rw & REQ_DISCARD)
		return;

711
	h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
712
713
714
	h->all_io_entry = dm_deferred_entry_inc(pool->all_io_ds);
}

715
static void issue(struct thin_c *tc, struct bio *bio)
716
717
718
719
{
	struct pool *pool = tc->pool;
	unsigned long flags;

720
721
722
723
724
	if (!bio_triggers_commit(tc, bio)) {
		generic_make_request(bio);
		return;
	}

725
	/*
726
727
728
	 * Complete bio with an error if earlier I/O caused changes to
	 * the metadata that can't be committed e.g, due to I/O errors
	 * on the metadata device.
729
	 */
730
731
732
733
734
735
736
737
738
739
740
741
	if (dm_thin_aborted_changes(tc->td)) {
		bio_io_error(bio);
		return;
	}

	/*
	 * Batch together any bios that trigger commits and then issue a
	 * single commit for them in process_deferred_bios().
	 */
	spin_lock_irqsave(&pool->lock, flags);
	bio_list_add(&pool->deferred_flush_bios, bio);
	spin_unlock_irqrestore(&pool->lock, flags);
742
743
}

744
745
746
747
748
749
750
751
752
753
754
755
756
static void remap_to_origin_and_issue(struct thin_c *tc, struct bio *bio)
{
	remap_to_origin(tc, bio);
	issue(tc, bio);
}

static void remap_and_issue(struct thin_c *tc, struct bio *bio,
			    dm_block_t block)
{
	remap(tc, bio, block);
	issue(tc, bio);
}

757
758
759
760
761
/*----------------------------------------------------------------*/

/*
 * Bio endio functions.
 */
Mike Snitzer's avatar
Mike Snitzer committed
762
struct dm_thin_new_mapping {
763
764
	struct list_head list;

765
	bool pass_discard:1;
Joe Thornber's avatar
Joe Thornber committed
766
	bool maybe_shared:1;
767

768
769
770
771
772
773
774
	/*
	 * Track quiescing, copying and zeroing preparation actions.  When this
	 * counter hits zero the block is prepared and can be inserted into the
	 * btree.
	 */
	atomic_t prepare_actions;

775
	int err;
776
	struct thin_c *tc;
Joe Thornber's avatar
Joe Thornber committed
777
	dm_block_t virt_begin, virt_end;
778
	dm_block_t data_block;
Joe Thornber's avatar
Joe Thornber committed
779
	struct dm_bio_prison_cell *cell;
780
781
782
783
784
785
786
787
788
789
790

	/*
	 * If the bio covers the whole area of a block then we can avoid
	 * zeroing or copying.  Instead this bio is hooked.  The bio will
	 * still be in the cell, so care has to be taken to avoid issuing
	 * the bio twice.
	 */
	struct bio *bio;
	bio_end_io_t *saved_bi_end_io;
};

791
static void __complete_mapping_preparation(struct dm_thin_new_mapping *m)
792
793
794
{
	struct pool *pool = m->tc->pool;

795
	if (atomic_dec_and_test(&m->prepare_actions)) {
796
		list_add_tail(&m->list, &pool->prepared_mappings);
797
798
799
800
		wake_worker(pool);
	}
}

801
static void complete_mapping_preparation(struct dm_thin_new_mapping *m)
802
803
804
805
806
{
	unsigned long flags;
	struct pool *pool = m->tc->pool;

	spin_lock_irqsave(&pool->lock, flags);
807
	__complete_mapping_preparation(m);
808
809
810
	spin_unlock_irqrestore(&pool->lock, flags);
}

811
812
813
814
815
816
817
818
static void copy_complete(int read_err, unsigned long write_err, void *context)
{
	struct dm_thin_new_mapping *m = context;

	m->err = read_err || write_err ? -EIO : 0;
	complete_mapping_preparation(m);
}

819
static void overwrite_endio(struct bio *bio)
820
{
821
	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
Mike Snitzer's avatar
Mike Snitzer committed
822
	struct dm_thin_new_mapping *m = h->overwrite_mapping;
823

824
825
	bio->bi_end_io = m->saved_bi_end_io;

826
	m->err = bio->bi_error;
827
	complete_mapping_preparation(m);
828
829
830
831
832
833
834
835
836
837
838
839
840
}

/*----------------------------------------------------------------*/

/*
 * Workqueue.
 */

/*
 * Prepared mapping jobs.
 */

/*
841
842
 * This sends the bios in the cell, except the original holder, back
 * to the deferred_bios list.
843
 */
844
static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *cell)
845
846
847
848
{
	struct pool *pool = tc->pool;
	unsigned long flags;

849
850
851
	spin_lock_irqsave(&tc->lock, flags);
	cell_release_no_holder(pool, cell, &tc->deferred_bio_list);
	spin_unlock_irqrestore(&tc->lock, flags);
852
853
854
855

	wake_worker(pool);
}

856
857
static void thin_defer_bio(struct thin_c *tc, struct bio *bio);

858
859
860
861
862
863
864
865
struct remap_info {
	struct thin_c *tc;
	struct bio_list defer_bios;
	struct bio_list issue_bios;
};

static void __inc_remap_and_issue_cell(void *context,
				       struct dm_bio_prison_cell *cell)
866
{
867
	struct remap_info *info = context;
868
869
	struct bio *bio;

870
	while ((bio = bio_list_pop(&cell->bios))) {
871
		if (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA))
872
			bio_list_add(&info->defer_bios, bio);
873
		else {
874
875
876
877
878
879
880
881
			inc_all_io_entry(info->tc->pool, bio);

			/*
			 * We can't issue the bios with the bio prison lock
			 * held, so we add them to a list to issue on
			 * return from this function.
			 */
			bio_list_add(&info->issue_bios, bio);
882
883
884
885
		}
	}
}

886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
static void inc_remap_and_issue_cell(struct thin_c *tc,
				     struct dm_bio_prison_cell *cell,
				     dm_block_t block)
{
	struct bio *bio;
	struct remap_info info;

	info.tc = tc;
	bio_list_init(&info.defer_bios);
	bio_list_init(&info.issue_bios);

	/*
	 * We have to be careful to inc any bios we're about to issue
	 * before the cell is released, and avoid a race with new bios
	 * being added to the cell.
	 */
	cell_visit_release(tc->pool, __inc_remap_and_issue_cell,
			   &info, cell);

	while ((bio = bio_list_pop(&info.defer_bios)))
		thin_defer_bio(tc, bio);

	while ((bio = bio_list_pop(&info.issue_bios)))
		remap_and_issue(info.tc, bio, block);
}

912
913
static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
{
914
	cell_error(m->tc->pool, m->cell);
915
916
917
	list_del(&m->list);
	mempool_free(m, m->tc->pool->mapping_pool);
}
918

Mike Snitzer's avatar
Mike Snitzer committed
919
static void process_prepared_mapping(struct dm_thin_new_mapping *m)
920
921
{
	struct thin_c *tc = m->tc;
922
	struct pool *pool = tc->pool;
923
	struct bio *bio = m->bio;
924
925
926
	int r;

	if (m->err) {
927
		cell_error(pool, m->cell);
928
		goto out;
929
930
931
932
933
934
935
	}

	/*
	 * Commit the prepared block into the mapping btree.
	 * Any I/O for this block arriving after this point will get
	 * remapped to it directly.
	 */
Joe Thornber's avatar
Joe Thornber committed
936
	r = dm_thin_insert_block(tc->td, m->virt_begin, m->data_block);
937
	if (r) {
938
		metadata_operation_failed(pool, "dm_thin_insert_block", r);
939
		cell_error(pool, m->cell);
940
		goto out;
941
942
943
944
945
946
947
948
949
	}

	/*
	 * Release any bios held while the block was being provisioned.
	 * If we are processing a write bio that completely covers the block,
	 * we already processed it so can ignore it now when processing
	 * the bios in the cell.
	 */
	if (bio) {
950
		inc_remap_and_issue_cell(tc, m->cell, m->data_block);
951
		bio_endio(bio);
952
953
954
955
956
	} else {
		inc_all_io_entry(tc->pool, m->cell->holder);
		remap_and_issue(tc, m->cell->holder, m->data_block);
		inc_remap_and_issue_cell(tc, m->cell, m->data_block);
	}
957

958
out:
959
	list_del(&m->list);
960
	mempool_free(m, pool->mapping_pool);
961
962
}

Joe Thornber's avatar
Joe Thornber committed
963
964
965
/*----------------------------------------------------------------*/

static void free_discard_mapping(struct dm_thin_new_mapping *m)
Joe Thornber's avatar
Joe Thornber committed
966
967
{
	struct thin_c *tc = m->tc;
Joe Thornber's avatar
Joe Thornber committed
968
969
970
971
	if (m->cell)
		cell_defer_no_holder(tc, m->cell);
	mempool_free(m, tc->pool->mapping_pool);
}
Joe Thornber's avatar
Joe Thornber committed
972

Joe Thornber's avatar
Joe Thornber committed
973
974
static void process_prepared_discard_fail(struct dm_thin_new_mapping *m)
{
975
	bio_io_error(m->bio);
Joe Thornber's avatar
Joe Thornber committed
976
977
978
979
980
	free_discard_mapping(m);
}

static void process_prepared_discard_success(struct dm_thin_new_mapping *m)
{
981
	bio_endio(m->bio);
Joe Thornber's avatar
Joe Thornber committed
982
983
984
985
986
987
988
989
990
991
992
993
994
	free_discard_mapping(m);
}

static void process_prepared_discard_no_passdown(struct dm_thin_new_mapping *m)
{
	int r;
	struct thin_c *tc = m->tc;

	r = dm_thin_remove_range(tc->td, m->cell->key.block_begin, m->cell->key.block_end);
	if (r) {
		metadata_operation_failed(tc->pool, "dm_thin_remove_range", r);
		bio_io_error(m->bio);
	} else
995
		bio_endio(m->bio);
Joe Thornber's avatar
Joe Thornber committed
996

997
	cell_defer_no_holder(tc, m->cell);
998
999
1000
	mempool_free(m, tc->pool->mapping_pool);
}

1001
1002
1003
/*----------------------------------------------------------------*/

static void passdown_double_checking_shared_status(struct dm_thin_new_mapping *m)
1004
{
Joe Thornber's avatar
Joe Thornber committed
1005
1006
1007
1008
	/*
	 * We've already unmapped this range of blocks, but before we
	 * passdown we have to check that these blocks are now unused.
	 */
1009
	int r = 0;
Joe Thornber's avatar
Joe Thornber committed
1010
	bool used = true;
1011
	struct thin_c *tc = m->tc;
Joe Thornber's avatar
Joe Thornber committed
1012
1013
	struct pool *pool = tc->pool;
	dm_block_t b = m->data_block, e, end = m->data_block + m->virt_end - m->virt_begin;
1014
	struct discard_op op;
Joe Thornber's avatar
Joe Thornber committed
1015

1016
	begin_discard(&op, tc, m->bio);
Joe Thornber's avatar
Joe Thornber committed
1017
1018
1019
1020
1021
	while (b != end) {
		/* find start of unmapped run */
		for (; b < end; b++) {
			r = dm_pool_block_is_used(pool->pmd, b, &used);
			if (r)
1022
				goto out;
1023

Joe Thornber's avatar
Joe Thornber committed
1024
1025
			if (!used)
				break;
1026
		}
Joe Thornber's avatar
Joe Thornber committed
1027

Joe Thornber's avatar
Joe Thornber committed
1028
1029
1030
1031
1032
1033
1034
		if (b == end)
			break;

		/* find end of run */
		for (e = b + 1; e != end; e++) {
			r = dm_pool_block_is_used(pool->pmd, e, &used);
			if (r)
1035
				goto out;
Joe Thornber's avatar
Joe Thornber committed
1036
1037
1038
1039
1040

			if (used)
				break;
		}

1041
		r = issue_discard(&op, b, e);
Joe Thornber's avatar
Joe Thornber committed
1042
		if (r)
1043
			goto out;
Joe Thornber's avatar
Joe Thornber committed
1044
1045
1046

		b = e;
	}
1047
1048
out:
	end_discard(&op, r);
Joe Thornber's avatar
Joe Thornber committed
1049
1050
}

Joe Thornber's avatar
Joe Thornber committed
1051
static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m)
1052
1053
1054
{
	int r;
	struct thin_c *tc = m->tc;
Joe Thornber's avatar
Joe Thornber committed
1055
	struct pool *pool = tc->pool;
1056

Joe Thornber's avatar
Joe Thornber committed
1057
	r = dm_thin_remove_range(tc->td, m->virt_begin, m->virt_end);
1058
	if (r) {
Joe Thornber's avatar
Joe Thornber committed
1059
		metadata_operation_failed(pool, "dm_thin_remove_range", r);
1060
		bio_io_error(m->bio);
Joe Thornber's avatar
Joe Thornber committed
1061

1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
	} else if (m->maybe_shared) {
		passdown_double_checking_shared_status(m);

	} else {
		struct discard_op op;
		begin_discard(&op, tc, m->bio);
		r = issue_discard(&op, m->data_block,
				  m->data_block + (m->virt_end - m->virt_begin));
		end_discard(&op, r);
	}
1072

Joe Thornber's avatar
Joe Thornber committed
1073
1074
	cell_defer_no_holder(tc, m->cell);
	mempool_free(m, pool->mapping_pool);
1075
1076
}

Joe Thornber's avatar
Joe Thornber committed
1077
static void process_prepared(struct pool *pool, struct list_head *head,
1078
			     process_mapping_fn *fn)
1079
1080
1081
{
	unsigned long flags;
	struct list_head maps;
Mike Snitzer's avatar
Mike Snitzer committed
1082
	struct dm_thin_new_mapping *m, *tmp;
1083
1084
1085

	INIT_LIST_HEAD(&maps);
	spin_lock_irqsave(&pool->lock, flags);
Joe Thornber's avatar
Joe Thornber committed
1086
	list_splice_init(head, &maps);
1087
1088
1089
	spin_unlock_irqrestore(&pool->lock, flags);

	list_for_each_entry_safe(m, tmp, &maps, list)
1090
		(*fn)(m);
1091
1092
1093
1094
1095
}

/*
 * Deferred bio jobs.
 */
Joe Thornber's avatar
Joe Thornber committed
1096
static int io_overlaps_block(struct pool *pool, struct bio *bio)
1097
{
1098
1099
	return bio->bi_iter.bi_size ==
		(pool->sectors_per_block << SECTOR_SHIFT);
Joe Thornber's avatar
Joe Thornber committed
1100
1101
1102
1103
1104
1105
}

static int io_overwrites_block(struct pool *pool, struct bio *bio)
{
	return (bio_data_dir(bio) == WRITE) &&
		io_overlaps_block(pool, bio);
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
}

static void save_and_set_endio(struct bio *bio, bio_end_io_t **save,
			       bio_end_io_t *fn)
{
	*save = bio->bi_end_io;
	bio->bi_end_io = fn;
}

static int ensure_next_mapping(struct pool *pool)
{
	if (pool->next_mapping)
		return 0;

	pool->next_mapping = mempool_alloc(pool->mapping_pool, GFP_ATOMIC);

	return pool->next_mapping ? 0 : -ENOMEM;
}

Mike Snitzer's avatar
Mike Snitzer committed
1125
static struct dm_thin_new_mapping *get_next_mapping(struct pool *pool)
1126
{
1127
	struct dm_thin_new_mapping *m = pool->next_mapping;
1128
1129
1130

	BUG_ON(!pool->next_mapping);

1131
1132
1133
1134
	memset(m, 0, sizeof(struct dm_thin_new_mapping));
	INIT_LIST_HEAD(&m->list);
	m->bio = NULL;

1135
1136
	pool->next_mapping = NULL;

1137
	return m;
1138
1139
}

1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
static void ll_zero(struct thin_c *tc, struct dm_thin_new_mapping *m,
		    sector_t begin, sector_t end)
{
	int r;
	struct dm_io_region to;

	to.bdev = tc->pool_dev->bdev;
	to.sector = begin;
	to.count = end - begin;

	r = dm_kcopyd_zero(tc->pool->copier, 1, &to, 0, copy_complete, m);
	if (r < 0) {
		DMERR_LIMIT("dm_kcopyd_zero() failed");
		copy_complete(1, 1, m);
	}
}

1157
static void remap_and_issue_overwrite(struct thin_c *tc, struct bio *bio,
Joe Thornber's avatar
Joe Thornber committed
1158
				      dm_block_t data_begin,
1159
1160
1161
1162
1163
1164
1165
1166
1167
				      struct dm_thin_new_mapping *m)
{
	struct pool *pool = tc->pool;
	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));

	h->overwrite_mapping = m;
	m->bio = bio;
	save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
	inc_all_io_entry(pool, bio);
Joe Thornber's avatar
Joe Thornber committed
1168
	remap_and_issue(tc, bio, data_begin);
1169
1170
}

1171
1172
1173
/*
 * A partial copy also needs to zero the uncopied region.
 */
1174
static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
1175
1176
			  struct dm_dev *origin, dm_block_t data_origin,
			  dm_block_t data_dest,
1177
1178
			  struct dm_bio_prison_cell *cell, struct bio *bio,
			  sector_t len)
1179
1180
1181
{
	int r;
	struct pool *pool = tc->pool;
Mike Snitzer's avatar
Mike Snitzer committed
1182
	struct dm_thin_new_mapping *m = get_next_mapping(pool);
1183
1184

	m->tc = tc;
Joe Thornber's avatar
Joe Thornber committed
1185
1186
	m->virt_begin = virt_block;
	m->virt_end = virt_block + 1u;
1187
1188
1189
	m->data_block = data_dest;
	m->cell = cell;

1190
1191
1192
1193
1194
1195
1196
	/*
	 * quiesce action + copy action + an extra reference held for the
	 * duration of this function (we may need to inc later for a
	 * partial zero).
	 */
	atomic_set(&m->prepare_actions, 3);

1197
	if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))
1198
		complete_mapping_preparation(m); /* already quiesced */
1199
1200
1201
1202
1203
1204
1205

	/*
	 * IO to pool_dev remaps to the pool target's data_dev.
	 *
	 * If the whole block of data is being overwritten, we can issue the
	 * bio immediately. Otherwise we use kcopyd to clone the data first.
	 */
1206
1207
1208
	if (io_overwrites_block(pool, bio))
		remap_and_issue_overwrite(tc, bio, data_dest, m);
	else {
1209
1210
		struct dm_io_region from, to;

1211
		from.bdev = origin->bdev;
1212
		from.sector = data_origin * pool->sectors_per_block;
1213
		from.count = len;
1214
1215
1216

		to.bdev = tc->pool_dev->bdev;
		to.sector = data_dest * pool->sectors_per_block;
1217
		to.count = len;
1218
1219
1220
1221

		r = dm_kcopyd_copy(pool->copier, &from, 1, &to,
				   0, copy_complete, m);
		if (r < 0) {
1222
			DMERR_LIMIT("dm_kcopyd_copy() failed");
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
			copy_complete(1, 1, m);

			/*
			 * We allow the zero to be issued, to simplify the
			 * error path.  Otherwise we'd need to start
			 * worrying about decrementing the prepare_actions
			 * counter.
			 */
		}

		/*
		 * Do we need to zero a tail region?
		 */
		if (len < pool->sectors_per_block && pool->pf.zero_new_blocks) {
			atomic_inc(&m->prepare_actions);
			ll_zero(tc, m,
				data_dest * pool->sectors_per_block + len,
				(data_dest + 1) * pool->sectors_per_block);
1241
1242
		}
	}
1243
1244

	complete_mapping_preparation(m); /* drop our ref */
1245
1246
}

1247
1248
static void schedule_internal_copy(struct thin_c *tc, dm_block_t virt_block,
				   dm_block_t data_origin, dm_block_t data_dest,
Mike Snitzer's avatar
Mike Snitzer committed
1249
				   struct dm_bio_prison_cell *cell, struct bio *bio)
1250
1251
{
	schedule_copy(tc, virt_block, tc->pool_dev,
1252
1253
		      data_origin, data_dest, cell, bio,
		      tc->pool->sectors_per_block);
1254
1255
}

1256
static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
Mike Snitzer's avatar
Mike Snitzer committed
1257
			  dm_block_t data_block, struct dm_bio_prison_cell *cell,
1258
1259
1260
			  struct bio *bio)
{
	struct pool *pool = tc->pool;
Mike Snitzer's avatar
Mike Snitzer committed
1261
	struct dm_thin_new_mapping *m = get_next_mapping(pool);
1262

1263
	atomic_set(&m->prepare_actions, 1); /* no need to quiesce */
1264
	m->tc = tc;
Joe Thornber's avatar
Joe Thornber committed
1265
1266
	m->virt_begin = virt_block;
	m->virt_end = virt_block + 1u;
1267
1268
1269
1270
1271
1272
1273
1274
	m->data_block = data_block;
	m->cell = cell;

	/*
	 * If the whole block of data is being overwritten or we are not
	 * zeroing pre-existing data, we can issue the bio immediately.
	 * Otherwise we use kcopyd to zero the data first.
	 */
1275
1276
1277
1278
1279
1280
1281
	if (pool->pf.zero_new_blocks) {
		if (io_overwrites_block(pool, bio))
			remap_and_issue_overwrite(tc, bio, data_block, m);
		else
			ll_zero(tc, m, data_block * pool->sectors_per_block,
				(data_block + 1) * pool->sectors_per_block);
	} else
1282
		process_prepared_mapping(m);
1283
}
Joe Thornber's avatar