dm-thin.c 65.8 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
/*
 * Copyright (C) 2011 Red Hat UK.
 *
 * This file is released under the GPL.
 */

#include "dm-thin-metadata.h"

#include <linux/device-mapper.h>
#include <linux/dm-io.h>
#include <linux/dm-kcopyd.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>

#define	DM_MSG_PREFIX	"thin"

/*
 * Tunable constants
 */
#define ENDIO_HOOK_POOL_SIZE 10240
#define DEFERRED_SET_SIZE 64
#define MAPPING_POOL_SIZE 1024
#define PRISON_CELLS 1024
26
#define COMMIT_PERIOD HZ
27
28
29
30
31
32
33
34
35
36
37
38
39
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

/*
 * 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
 * including all devices that share this block.  (see deferred_set code)
 *
 * 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
66
 * (process_prepared_mapping).  This act of inserting breaks some
67
68
69
70
71
72
73
74
75
76
77
78
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
115
116
117
 * 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.
 */

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

/*
 * Sometimes we can't deal with a bio straight away.  We put them in prison
 * where they can't cause any mischief.  Bios are put in a cell identified
 * by a key, multiple bios can be in the same cell.  When the cell is
 * subsequently unlocked the bios become available.
 */
struct bio_prison;

struct cell_key {
	int virtual;
	dm_thin_id dev;
	dm_block_t block;
};

struct cell {
	struct hlist_node list;
	struct bio_prison *prison;
	struct cell_key key;
118
	struct bio *holder;
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
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
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
	struct bio_list bios;
};

struct bio_prison {
	spinlock_t lock;
	mempool_t *cell_pool;

	unsigned nr_buckets;
	unsigned hash_mask;
	struct hlist_head *cells;
};

static uint32_t calc_nr_buckets(unsigned nr_cells)
{
	uint32_t n = 128;

	nr_cells /= 4;
	nr_cells = min(nr_cells, 8192u);

	while (n < nr_cells)
		n <<= 1;

	return n;
}

/*
 * @nr_cells should be the number of cells you want in use _concurrently_.
 * Don't confuse it with the number of distinct keys.
 */
static struct bio_prison *prison_create(unsigned nr_cells)
{
	unsigned i;
	uint32_t nr_buckets = calc_nr_buckets(nr_cells);
	size_t len = sizeof(struct bio_prison) +
		(sizeof(struct hlist_head) * nr_buckets);
	struct bio_prison *prison = kmalloc(len, GFP_KERNEL);

	if (!prison)
		return NULL;

	spin_lock_init(&prison->lock);
	prison->cell_pool = mempool_create_kmalloc_pool(nr_cells,
							sizeof(struct cell));
	if (!prison->cell_pool) {
		kfree(prison);
		return NULL;
	}

	prison->nr_buckets = nr_buckets;
	prison->hash_mask = nr_buckets - 1;
	prison->cells = (struct hlist_head *) (prison + 1);
	for (i = 0; i < nr_buckets; i++)
		INIT_HLIST_HEAD(prison->cells + i);

	return prison;
}

static void prison_destroy(struct bio_prison *prison)
{
	mempool_destroy(prison->cell_pool);
	kfree(prison);
}

static uint32_t hash_key(struct bio_prison *prison, struct cell_key *key)
{
	const unsigned long BIG_PRIME = 4294967291UL;
	uint64_t hash = key->block * BIG_PRIME;

	return (uint32_t) (hash & prison->hash_mask);
}

static int keys_equal(struct cell_key *lhs, struct cell_key *rhs)
{
	       return (lhs->virtual == rhs->virtual) &&
		       (lhs->dev == rhs->dev) &&
		       (lhs->block == rhs->block);
}

static struct cell *__search_bucket(struct hlist_head *bucket,
				    struct cell_key *key)
{
	struct cell *cell;
	struct hlist_node *tmp;

	hlist_for_each_entry(cell, tmp, bucket, list)
		if (keys_equal(&cell->key, key))
			return cell;

	return NULL;
}

/*
 * This may block if a new cell needs allocating.  You must ensure that
 * cells will be unlocked even if the calling thread is blocked.
 *
214
 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
215
216
217
218
 */
static int bio_detain(struct bio_prison *prison, struct cell_key *key,
		      struct bio *inmate, struct cell **ref)
{
219
	int r = 1;
220
221
	unsigned long flags;
	uint32_t hash = hash_key(prison, key);
222
	struct cell *cell, *cell2;
223
224
225
226
227

	BUG_ON(hash > prison->nr_buckets);

	spin_lock_irqsave(&prison->lock, flags);

228
229
230
231
	cell = __search_bucket(prison->cells + hash, key);
	if (cell) {
		bio_list_add(&cell->bios, inmate);
		goto out;
232
233
	}

234
235
236
	/*
	 * Allocate a new cell
	 */
237
	spin_unlock_irqrestore(&prison->lock, flags);
238
239
	cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
	spin_lock_irqsave(&prison->lock, flags);
240

241
242
243
244
245
246
	/*
	 * We've been unlocked, so we have to double check that
	 * nobody else has inserted this cell in the meantime.
	 */
	cell = __search_bucket(prison->cells + hash, key);
	if (cell) {
247
		mempool_free(cell2, prison->cell_pool);
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
		bio_list_add(&cell->bios, inmate);
		goto out;
	}

	/*
	 * Use new cell.
	 */
	cell = cell2;

	cell->prison = prison;
	memcpy(&cell->key, key, sizeof(cell->key));
	cell->holder = inmate;
	bio_list_init(&cell->bios);
	hlist_add_head(&cell->list, prison->cells + hash);

	r = 0;

out:
	spin_unlock_irqrestore(&prison->lock, flags);
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281

	*ref = cell;

	return r;
}

/*
 * @inmates must have been initialised prior to this call
 */
static void __cell_release(struct cell *cell, struct bio_list *inmates)
{
	struct bio_prison *prison = cell->prison;

	hlist_del(&cell->list);

282
283
284
285
	if (inmates) {
		bio_list_add(inmates, cell->holder);
		bio_list_merge(inmates, &cell->bios);
	}
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305

	mempool_free(cell, prison->cell_pool);
}

static void cell_release(struct cell *cell, struct bio_list *bios)
{
	unsigned long flags;
	struct bio_prison *prison = cell->prison;

	spin_lock_irqsave(&prison->lock, flags);
	__cell_release(cell, bios);
	spin_unlock_irqrestore(&prison->lock, flags);
}

/*
 * There are a couple of places where we put a bio into a cell briefly
 * before taking it out again.  In these situations we know that no other
 * bio may be in the cell.  This function releases the cell, and also does
 * a sanity check.
 */
306
307
308
309
static void __cell_release_singleton(struct cell *cell, struct bio *bio)
{
	BUG_ON(cell->holder != bio);
	BUG_ON(!bio_list_empty(&cell->bios));
310
311

	__cell_release(cell, NULL);
312
313
}

314
315
316
static void cell_release_singleton(struct cell *cell, struct bio *bio)
{
	unsigned long flags;
317
	struct bio_prison *prison = cell->prison;
318
319

	spin_lock_irqsave(&prison->lock, flags);
320
	__cell_release_singleton(cell, bio);
321
	spin_unlock_irqrestore(&prison->lock, flags);
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
}

/*
 * Sometimes we don't want the holder, just the additional bios.
 */
static void __cell_release_no_holder(struct cell *cell, struct bio_list *inmates)
{
	struct bio_prison *prison = cell->prison;

	hlist_del(&cell->list);
	bio_list_merge(inmates, &cell->bios);

	mempool_free(cell, prison->cell_pool);
}

static void cell_release_no_holder(struct cell *cell, struct bio_list *inmates)
{
	unsigned long flags;
	struct bio_prison *prison = cell->prison;
341

342
343
344
	spin_lock_irqsave(&prison->lock, flags);
	__cell_release_no_holder(cell, inmates);
	spin_unlock_irqrestore(&prison->lock, flags);
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
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
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
}

static void cell_error(struct cell *cell)
{
	struct bio_prison *prison = cell->prison;
	struct bio_list bios;
	struct bio *bio;
	unsigned long flags;

	bio_list_init(&bios);

	spin_lock_irqsave(&prison->lock, flags);
	__cell_release(cell, &bios);
	spin_unlock_irqrestore(&prison->lock, flags);

	while ((bio = bio_list_pop(&bios)))
		bio_io_error(bio);
}

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

/*
 * We use the deferred set to keep track of pending reads to shared blocks.
 * We do this to ensure the new mapping caused by a write isn't performed
 * until these prior reads have completed.  Otherwise the insertion of the
 * new mapping could free the old block that the read bios are mapped to.
 */

struct deferred_set;
struct deferred_entry {
	struct deferred_set *ds;
	unsigned count;
	struct list_head work_items;
};

struct deferred_set {
	spinlock_t lock;
	unsigned current_entry;
	unsigned sweeper;
	struct deferred_entry entries[DEFERRED_SET_SIZE];
};

static void ds_init(struct deferred_set *ds)
{
	int i;

	spin_lock_init(&ds->lock);
	ds->current_entry = 0;
	ds->sweeper = 0;
	for (i = 0; i < DEFERRED_SET_SIZE; i++) {
		ds->entries[i].ds = ds;
		ds->entries[i].count = 0;
		INIT_LIST_HEAD(&ds->entries[i].work_items);
	}
}

static struct deferred_entry *ds_inc(struct deferred_set *ds)
{
	unsigned long flags;
	struct deferred_entry *entry;

	spin_lock_irqsave(&ds->lock, flags);
	entry = ds->entries + ds->current_entry;
	entry->count++;
	spin_unlock_irqrestore(&ds->lock, flags);

	return entry;
}

static unsigned ds_next(unsigned index)
{
	return (index + 1) % DEFERRED_SET_SIZE;
}

static void __sweep(struct deferred_set *ds, struct list_head *head)
{
	while ((ds->sweeper != ds->current_entry) &&
	       !ds->entries[ds->sweeper].count) {
		list_splice_init(&ds->entries[ds->sweeper].work_items, head);
		ds->sweeper = ds_next(ds->sweeper);
	}

	if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
		list_splice_init(&ds->entries[ds->sweeper].work_items, head);
}

static void ds_dec(struct deferred_entry *entry, struct list_head *head)
{
	unsigned long flags;

	spin_lock_irqsave(&entry->ds->lock, flags);
	BUG_ON(!entry->count);
	--entry->count;
	__sweep(entry->ds, head);
	spin_unlock_irqrestore(&entry->ds->lock, flags);
}

/*
 * Returns 1 if deferred or 0 if no pending items to delay job.
 */
static int ds_add_work(struct deferred_set *ds, struct list_head *work)
{
	int r = 1;
	unsigned long flags;
	unsigned next_entry;

	spin_lock_irqsave(&ds->lock, flags);
	if ((ds->sweeper == ds->current_entry) &&
	    !ds->entries[ds->current_entry].count)
		r = 0;
	else {
		list_add(work, &ds->entries[ds->current_entry].work_items);
		next_entry = ds_next(ds->current_entry);
		if (!ds->entries[next_entry].count)
			ds->current_entry = next_entry;
	}
	spin_unlock_irqrestore(&ds->lock, flags);

	return r;
}

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

/*
 * Key building.
 */
static void build_data_key(struct dm_thin_device *td,
			   dm_block_t b, struct cell_key *key)
{
	key->virtual = 0;
	key->dev = dm_thin_dev_id(td);
	key->block = b;
}

static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
			      struct cell_key *key)
{
	key->virtual = 1;
	key->dev = dm_thin_dev_id(td);
	key->block = b;
}

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

/*
 * A pool device ties together a metadata device and a data device.  It
 * also provides the interface for creating and destroying internal
 * devices.
 */
struct new_mapping;
495
496
497
498
499
500
501

struct pool_features {
	unsigned zero_new_blocks:1;
	unsigned discard_enabled:1;
	unsigned discard_passdown:1;
};

502
503
504
505
506
507
508
509
510
511
512
513
514
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;

	uint32_t sectors_per_block;
	unsigned block_shift;
	dm_block_t offset_mask;
	dm_block_t low_water_blocks;

515
	struct pool_features pf;
516
517
518
519
520
521
522
523
	unsigned low_water_triggered:1;	/* A dm event has been sent */
	unsigned no_free_space:1;	/* A -ENOSPC warning has been issued */

	struct bio_prison *prison;
	struct dm_kcopyd_client *copier;

	struct workqueue_struct *wq;
	struct work_struct worker;
524
	struct delayed_work waker;
525
526

	unsigned ref_count;
527
	unsigned long last_commit_jiffies;
528
529
530
531
532

	spinlock_t lock;
	struct bio_list deferred_bios;
	struct bio_list deferred_flush_bios;
	struct list_head prepared_mappings;
Joe Thornber's avatar
Joe Thornber committed
533
	struct list_head prepared_discards;
534
535
536

	struct bio_list retry_on_resume_list;

537
	struct deferred_set shared_read_ds;
Joe Thornber's avatar
Joe Thornber committed
538
	struct deferred_set all_io_ds;
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555

	struct new_mapping *next_mapping;
	mempool_t *mapping_pool;
	mempool_t *endio_hook_pool;
};

/*
 * 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;
556
	struct pool_features pf;
557
558
559
560
561
562
563
};

/*
 * Target context for a thin.
 */
struct thin_c {
	struct dm_dev *pool_dev;
564
	struct dm_dev *origin_dev;
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
	dm_thin_id dev_id;

	struct pool *pool;
	struct dm_thin_device *td;
};

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

/*
 * 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;
}

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

633
634
635
struct endio_hook {
	struct thin_c *tc;
	struct deferred_entry *shared_read_entry;
Joe Thornber's avatar
Joe Thornber committed
636
	struct deferred_entry *all_io_entry;
637
638
639
	struct new_mapping *overwrite_mapping;
};

640
641
642
643
644
645
646
647
648
649
static void __requeue_bio_list(struct thin_c *tc, struct bio_list *master)
{
	struct bio *bio;
	struct bio_list bios;

	bio_list_init(&bios);
	bio_list_merge(&bios, master);
	bio_list_init(master);

	while ((bio = bio_list_pop(&bios))) {
650
651
		struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
		if (h->tc == tc)
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
678
679
680
681
682
683
684
685
686
687
688
689
			bio_endio(bio, DM_ENDIO_REQUEUE);
		else
			bio_list_add(master, bio);
	}
}

static void requeue_io(struct thin_c *tc)
{
	struct pool *pool = tc->pool;
	unsigned long flags;

	spin_lock_irqsave(&pool->lock, flags);
	__requeue_bio_list(tc, &pool->deferred_bios);
	__requeue_bio_list(tc, &pool->retry_on_resume_list);
	spin_unlock_irqrestore(&pool->lock, flags);
}

/*
 * 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)
{
	return bio->bi_sector >> tc->pool->block_shift;
}

static void remap(struct thin_c *tc, struct bio *bio, dm_block_t block)
{
	struct pool *pool = tc->pool;

	bio->bi_bdev = tc->pool_dev->bdev;
	bio->bi_sector = (block << pool->block_shift) +
		(bio->bi_sector & pool->offset_mask);
}

690
691
692
693
694
695
static void remap_to_origin(struct thin_c *tc, struct bio *bio)
{
	bio->bi_bdev = tc->origin_dev->bdev;
}

static void issue(struct thin_c *tc, struct bio *bio)
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
{
	struct pool *pool = tc->pool;
	unsigned long flags;

	/*
	 * Batch together any FUA/FLUSH bios we find and then issue
	 * a single commit for them in process_deferred_bios().
	 */
	if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
		spin_lock_irqsave(&pool->lock, flags);
		bio_list_add(&pool->deferred_flush_bios, bio);
		spin_unlock_irqrestore(&pool->lock, flags);
	} else
		generic_make_request(bio);
}

712
713
714
715
716
717
718
719
720
721
722
723
724
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);
}

725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
/*
 * 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);
}

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

/*
 * Bio endio functions.
 */
struct new_mapping {
	struct list_head list;

742
743
	unsigned quiesced:1;
	unsigned prepared:1;
Joe Thornber's avatar
Joe Thornber committed
744
	unsigned pass_discard:1;
745
746
747
748

	struct thin_c *tc;
	dm_block_t virt_block;
	dm_block_t data_block;
Joe Thornber's avatar
Joe Thornber committed
749
	struct cell *cell, *cell2;
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
	int err;

	/*
	 * 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;
};

static void __maybe_add_mapping(struct new_mapping *m)
{
	struct pool *pool = m->tc->pool;

766
	if (m->quiesced && m->prepared) {
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
		list_add(&m->list, &pool->prepared_mappings);
		wake_worker(pool);
	}
}

static void copy_complete(int read_err, unsigned long write_err, void *context)
{
	unsigned long flags;
	struct new_mapping *m = context;
	struct pool *pool = m->tc->pool;

	m->err = read_err || write_err ? -EIO : 0;

	spin_lock_irqsave(&pool->lock, flags);
	m->prepared = 1;
	__maybe_add_mapping(m);
	spin_unlock_irqrestore(&pool->lock, flags);
}

static void overwrite_endio(struct bio *bio, int err)
{
	unsigned long flags;
789
790
	struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
	struct new_mapping *m = h->overwrite_mapping;
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
	struct pool *pool = m->tc->pool;

	m->err = err;

	spin_lock_irqsave(&pool->lock, flags);
	m->prepared = 1;
	__maybe_add_mapping(m);
	spin_unlock_irqrestore(&pool->lock, flags);
}

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

/*
 * Workqueue.
 */

/*
 * Prepared mapping jobs.
 */

/*
 * This sends the bios in the cell back to the deferred_bios list.
 */
static void cell_defer(struct thin_c *tc, struct cell *cell,
		       dm_block_t data_block)
{
	struct pool *pool = tc->pool;
	unsigned long flags;

	spin_lock_irqsave(&pool->lock, flags);
	cell_release(cell, &pool->deferred_bios);
	spin_unlock_irqrestore(&tc->pool->lock, flags);

	wake_worker(pool);
}

/*
 * Same as cell_defer above, except it omits one particular detainee,
 * a write bio that covers the block and has already been processed.
 */
831
static void cell_defer_except(struct thin_c *tc, struct cell *cell)
832
833
834
835
836
837
838
839
{
	struct bio_list bios;
	struct pool *pool = tc->pool;
	unsigned long flags;

	bio_list_init(&bios);

	spin_lock_irqsave(&pool->lock, flags);
840
	cell_release_no_holder(cell, &pool->deferred_bios);
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
	spin_unlock_irqrestore(&pool->lock, flags);

	wake_worker(pool);
}

static void process_prepared_mapping(struct new_mapping *m)
{
	struct thin_c *tc = m->tc;
	struct bio *bio;
	int r;

	bio = m->bio;
	if (bio)
		bio->bi_end_io = m->saved_bi_end_io;

	if (m->err) {
		cell_error(m->cell);
		return;
	}

	/*
	 * Commit the prepared block into the mapping btree.
	 * Any I/O for this block arriving after this point will get
	 * remapped to it directly.
	 */
	r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
	if (r) {
		DMERR("dm_thin_insert_block() failed");
		cell_error(m->cell);
		return;
	}

	/*
	 * 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) {
880
		cell_defer_except(tc, m->cell);
881
882
883
884
885
886
887
888
		bio_endio(bio, 0);
	} else
		cell_defer(tc, m->cell, m->data_block);

	list_del(&m->list);
	mempool_free(m, tc->pool->mapping_pool);
}

Joe Thornber's avatar
Joe Thornber committed
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
static void process_prepared_discard(struct new_mapping *m)
{
	int r;
	struct thin_c *tc = m->tc;

	r = dm_thin_remove_block(tc->td, m->virt_block);
	if (r)
		DMERR("dm_thin_remove_block() failed");

	/*
	 * Pass the discard down to the underlying device?
	 */
	if (m->pass_discard)
		remap_and_issue(tc, m->bio, m->data_block);
	else
		bio_endio(m->bio, 0);

	cell_defer_except(tc, m->cell);
	cell_defer_except(tc, m->cell2);
	mempool_free(m, tc->pool->mapping_pool);
}

static void process_prepared(struct pool *pool, struct list_head *head,
			     void (*fn)(struct new_mapping *))
913
914
915
916
917
918
919
{
	unsigned long flags;
	struct list_head maps;
	struct new_mapping *m, *tmp;

	INIT_LIST_HEAD(&maps);
	spin_lock_irqsave(&pool->lock, flags);
Joe Thornber's avatar
Joe Thornber committed
920
	list_splice_init(head, &maps);
921
922
923
	spin_unlock_irqrestore(&pool->lock, flags);

	list_for_each_entry_safe(m, tmp, &maps, list)
Joe Thornber's avatar
Joe Thornber committed
924
		fn(m);
925
926
927
928
929
}

/*
 * Deferred bio jobs.
 */
Joe Thornber's avatar
Joe Thornber committed
930
static int io_overlaps_block(struct pool *pool, struct bio *bio)
931
{
Joe Thornber's avatar
Joe Thornber committed
932
	return !(bio->bi_sector & pool->offset_mask) &&
933
		(bio->bi_size == (pool->sectors_per_block << SECTOR_SHIFT));
Joe Thornber's avatar
Joe Thornber committed
934
935
936
937
938
939
940

}

static int io_overwrites_block(struct pool *pool, struct bio *bio)
{
	return (bio_data_dir(bio) == WRITE) &&
		io_overlaps_block(pool, bio);
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
}

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;
}

static struct new_mapping *get_next_mapping(struct pool *pool)
{
	struct new_mapping *r = pool->next_mapping;

	BUG_ON(!pool->next_mapping);

	pool->next_mapping = NULL;

	return r;
}

static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
972
973
			  struct dm_dev *origin, dm_block_t data_origin,
			  dm_block_t data_dest,
974
975
976
977
978
979
980
			  struct cell *cell, struct bio *bio)
{
	int r;
	struct pool *pool = tc->pool;
	struct new_mapping *m = get_next_mapping(pool);

	INIT_LIST_HEAD(&m->list);
981
	m->quiesced = 0;
982
983
984
985
986
987
988
989
	m->prepared = 0;
	m->tc = tc;
	m->virt_block = virt_block;
	m->data_block = data_dest;
	m->cell = cell;
	m->err = 0;
	m->bio = NULL;

990
991
	if (!ds_add_work(&pool->shared_read_ds, &m->list))
		m->quiesced = 1;
992
993
994
995
996
997
998
999

	/*
	 * 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.
	 */
	if (io_overwrites_block(pool, bio)) {
1000
1001
		struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
		h->overwrite_mapping = m;
1002
1003
1004
1005
1006
1007
		m->bio = bio;
		save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
		remap_and_issue(tc, bio, data_dest);
	} else {
		struct dm_io_region from, to;

1008
		from.bdev = origin->bdev;
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
		from.sector = data_origin * pool->sectors_per_block;
		from.count = pool->sectors_per_block;

		to.bdev = tc->pool_dev->bdev;
		to.sector = data_dest * pool->sectors_per_block;
		to.count = pool->sectors_per_block;

		r = dm_kcopyd_copy(pool->copier, &from, 1, &to,
				   0, copy_complete, m);
		if (r < 0) {
			mempool_free(m, pool->mapping_pool);
			DMERR("dm_kcopyd_copy() failed");
			cell_error(cell);
		}
	}
}

1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
static void schedule_internal_copy(struct thin_c *tc, dm_block_t virt_block,
				   dm_block_t data_origin, dm_block_t data_dest,
				   struct cell *cell, struct bio *bio)
{
	schedule_copy(tc, virt_block, tc->pool_dev,
		      data_origin, data_dest, cell, bio);
}

static void schedule_external_copy(struct thin_c *tc, dm_block_t virt_block,
				   dm_block_t data_dest,
				   struct cell *cell, struct bio *bio)
{
	schedule_copy(tc, virt_block, tc->origin_dev,
		      virt_block, data_dest, cell, bio);
}

1042
1043
1044
1045
1046
1047
1048
1049
static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
			  dm_block_t data_block, struct cell *cell,
			  struct bio *bio)
{
	struct pool *pool = tc->pool;
	struct new_mapping *m = get_next_mapping(pool);

	INIT_LIST_HEAD(&m->list);
1050
	m->quiesced = 1;
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
	m->prepared = 0;
	m->tc = tc;
	m->virt_block = virt_block;
	m->data_block = data_block;
	m->cell = cell;
	m->err = 0;
	m->bio = NULL;

	/*
	 * 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.
	 */
1064
	if (!pool->pf.zero_new_blocks)
1065
1066
1067
		process_prepared_mapping(m);

	else if (io_overwrites_block(pool, bio)) {
1068
1069
		struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
		h->overwrite_mapping = m;
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
		m->bio = bio;
		save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
		remap_and_issue(tc, bio, data_block);

	} else {
		int r;
		struct dm_io_region to;

		to.bdev = tc->pool_dev->bdev;
		to.sector = data_block * pool->sectors_per_block;
		to.count = pool->sectors_per_block;

		r = dm_kcopyd_zero(pool->copier, 1, &to, 0, copy_complete, m);
		if (r < 0) {
			mempool_free(m, pool->mapping_pool);
			DMERR("dm_kcopyd_zero() failed");
			cell_error(cell);
		}
	}
}

static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
{
	int r;
	dm_block_t free_blocks;
	unsigned long flags;
	struct pool *pool = tc->pool;

	r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
	if (r)
		return r;

	if (free_blocks <= pool->low_water_blocks && !pool->low_water_triggered) {
		DMWARN("%s: reached low water mark, sending event.",
		       dm_device_name(pool->pool_md));
		spin_lock_irqsave(&pool->lock, flags);
		pool->low_water_triggered = 1;
		spin_unlock_irqrestore(&pool->lock, flags);
		dm_table_event(pool->ti->table);
	}

	if (!free_blocks) {
		if (pool->no_free_space)
			return -ENOSPC;
		else {
			/*
			 * Try to commit to see if that will free up some
			 * more space.
			 */
			r = dm_pool_commit_metadata(pool->pmd);
			if (r) {
				DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
				      __func__, r);
				return r;
			}

			r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
			if (r)
				return r;

			/*
			 * If we still have no space we set a flag to avoid
			 * doing all this checking and return -ENOSPC.
			 */
			if (!free_blocks) {
				DMWARN("%s: no free space available.",
				       dm_device_name(pool->pool_md));
				spin_lock_irqsave(&pool->lock, flags);
				pool->no_free_space = 1;
				spin_unlock_irqrestore(&pool->lock, flags);
				return -ENOSPC;
			}
		}
	}

	r = dm_pool_alloc_data_block(pool->pmd, result);
	if (r)
		return r;

	return 0;
}

/*
 * If we have run out of space, queue bios until the device is
 * resumed, presumably after having been reloaded with more space.
 */
static void retry_on_resume(struct bio *bio)
{
1158
1159
	struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
	struct thin_c *tc = h->tc;
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
	struct pool *pool = tc->pool;
	unsigned long flags;

	spin_lock_irqsave(&pool->lock, flags);
	bio_list_add(&pool->retry_on_resume_list, bio);
	spin_unlock_irqrestore(&pool->lock, flags);
}

static void no_space(struct cell *cell)
{
	struct bio *bio;
	struct bio_list bios;

	bio_list_init(&bios);
	cell_release(cell, &bios);

	while ((bio = bio_list_pop(&bios)))
		retry_on_resume(bio);
}

Joe Thornber's avatar
Joe Thornber committed
1180
1181
1182
static void process_discard(struct thin_c *tc, struct bio *bio)
{
	int r;
1183
	unsigned long flags;
Joe Thornber's avatar
Joe Thornber committed
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
	struct pool *pool = tc->pool;
	struct cell *cell, *cell2;
	struct cell_key key, key2;
	dm_block_t block = get_bio_block(tc, bio);
	struct dm_thin_lookup_result lookup_result;
	struct new_mapping *m;

	build_virtual_key(tc->td, block, &key);
	if (bio_detain(tc->pool->prison, &key, bio, &cell))
		return;

	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
	switch (r) {
	case 0:
		/*
		 * Check nobody is fiddling with this pool block.  This can
		 * happen if someone's in the process of breaking sharing
		 * on this block.
		 */
		build_data_key(tc->td, lookup_result.block, &key2);
		if (bio_detain(tc->pool->prison, &key2, bio, &cell2)) {
			cell_release_singleton(cell, bio);
			break;
		}

		if (io_overlaps_block(pool, bio)) {
			/*
			 * IO may still be going to the destination block.  We must
			 * quiesce before we can do the removal.
			 */
			m = get_next_mapping(pool);
			m->tc = tc;
1216
			m->pass_discard = (!lookup_result.shared) & pool->pf.discard_passdown;
Joe Thornber's avatar
Joe Thornber committed
1217
1218
1219
1220
1221
1222
1223
1224
			m->virt_block = block;
			m->data_block = lookup_result.block;
			m->cell = cell;
			m->cell2 = cell2;
			m->err = 0;
			m->bio = bio;

			if (!ds_add_work(&pool->all_io_ds, &m->list)) {
1225
				spin_lock_irqsave(&pool->lock, flags);
Joe Thornber's avatar
Joe Thornber committed
1226
				list_add(&m->list, &pool->prepared_discards);
1227
				spin_unlock_irqrestore(&pool->lock, flags);
Joe Thornber's avatar
Joe Thornber committed
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
				wake_worker(pool);
			}
		} else {
			/*
			 * This path is hit if people are ignoring
			 * limits->discard_granularity.  It ignores any
			 * part of the discard that is in a subsequent
			 * block.
			 */
			sector_t offset = bio->bi_sector - (block << pool->block_shift);
			unsigned remaining = (pool->sectors_per_block - offset) << 9;
			bio->bi_size = min(bio->bi_size, remaining);

			cell_release_singleton(cell, bio);
			cell_release_singleton(cell2, bio);
			remap_and_issue(tc, bio, lookup_result.block);
		}
		break;

	case -ENODATA:
		/*
		 * It isn't provisioned, just forget it.
		 */
		cell_release_singleton(cell, bio);
		bio_endio(bio, 0);
		break;

	default:
		DMERR("discard: find block unexpectedly returned %d", r);
		cell_release_singleton(cell, bio);
		bio_io_error(bio);
		break;
	}
}

1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
			  struct cell_key *key,
			  struct dm_thin_lookup_result *lookup_result,
			  struct cell *cell)
{
	int r;
	dm_block_t data_block;

	r = alloc_data_block(tc, &data_block);
	switch (r) {
	case 0:
1274
1275
		schedule_internal_copy(tc, block, lookup_result->block,
				       data_block, cell, bio);
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
		break;

	case -ENOSPC:
		no_space(cell);
		break;

	default:
		DMERR("%s: alloc_data_block() failed, error = %d", __func__, r);
		cell_error(cell);
		break;
	}
}

static void process_shared_bio(struct thin_c *tc, struct bio *bio,
			       dm_block_t block,
			       struct dm_thin_lookup_result *lookup_result)
{
	struct cell *cell;
	struct pool *pool = tc->pool;
	struct cell_key key;

	/*
	 * If cell is already occupied, then sharing is already in the process
	 * of being broken so we have nothing further to do here.
	 */
	build_data_key(tc->td, lookup_result->block, &key);
	if (bio_detain(pool->prison, &key, bio, &cell))
		return;

	if (bio_data_dir(bio) == WRITE)
		break_sharing(tc, bio, block, &key, lookup_result, cell);
	else {
1308
		struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
1309

1310
		h->shared_read_entry = ds_inc(&pool->shared_read_ds);
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344

		cell_release_singleton(cell, bio);
		remap_and_issue(tc, bio, lookup_result->block);
	}
}

static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block,
			    struct cell *cell)
{
	int r;
	dm_block_t data_block;

	/*
	 * Remap empty bios (flushes) immediately, without provisioning.
	 */
	if (!bio->bi_size) {
		cell_release_singleton(cell, bio);
		remap_and_issue(tc, bio, 0);
		return;
	}

	/*
	 * Fill read bios with zeroes and complete them immediately.
	 */
	if (bio_data_dir(bio) == READ) {
		zero_fill_bio(bio);
		cell_release_singleton(cell, bio);
		bio_endio(bio, 0);
		return;
	}

	r = alloc_data_block(tc, &data_block);
	switch (r) {
	case 0:
1345
1346
1347
1348
		if (tc->origin_dev)
			schedule_external_copy(tc, block, data_block, cell, bio);
		else
			schedule_zero(tc, block, data_block, cell, bio);
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
		break;

	case -ENOSPC:
		no_space(cell);
		break;

	default:
		DMERR("%s: alloc_data_block() failed, error = %d", __func__, r);
		cell_error(cell);
		break;
	}
}

static void process_bio(struct thin_c *tc, struct bio *bio)
{
	int r;
	dm_block_t block = get_bio_block(tc, bio);
	struct cell *cell;
	struct cell_key key;
	struct dm_thin_lookup_result lookup_result;

	/*
	 * If cell is already occupied, then the block is already
	 * being provisioned so we have nothing further to do here.
	 */
	build_virtual_key(tc->td, block, &key);
	if (bio_detain(tc->pool->prison, &key, bio, &cell))
		return;

	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
	switch (r) {
	case 0:
		/*
		 * We can release this cell now.  This thread is the only
		 * one that puts bios into a cell, and we know there were
		 * no preceding bios.
		 */
		/*
		 * TODO: this will probably have to change when discard goes
		 * back in.
		 */
		cell_release_singleton(cell, bio);

		if (lookup_result.shared)
			process_shared_bio(tc, bio, block, &lookup_result);
		else
			remap_and_issue(tc, bio, lookup_result.block);
		break;

	case -ENODATA:
1399
1400
1401
1402
1403
		if (bio_data_dir(bio) == READ && tc->origin_dev) {
			cell_release_singleton(cell, bio);
			remap_to_origin_and_issue(tc, bio);
		} else
			provision_block(tc, bio, block, cell);
1404
1405
1406
1407
		break;

	default:
		DMERR("dm_thin_find_block() failed, error = %d", r);
Joe Thornber's avatar
Joe Thornber committed
1408
		cell_release_singleton(cell, bio);
1409
1410
1411
1412
1413
		bio_io_error(bio);
		break;
	}
}

1414
1415
1416
1417
1418
1419
static int need_commit_due_to_time(struct pool *pool)
{
	return jiffies < pool->last_commit_jiffies ||
	       jiffies > pool->last_commit_jiffies + COMMIT_PERIOD;
}

1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
static void process_deferred_bios(struct pool *pool)
{
	unsigned long flags;
	struct bio *bio;
	struct bio_list bios;
	int r;

	bio_list_init(&bios);

	spin_lock_irqsave(&pool->lock, flags);
	bio_list_merge(&bios, &pool->deferred_bios);
	bio_list_init(&pool->deferred_bios);
	spin_unlock_irqrestore(&pool->lock, flags);

	while ((bio = bio_list_pop(&bios))) {
1435
1436
1437
		struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
		struct thin_c *tc = h->tc;

1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
		/*
		 * If we've got no free new_mapping structs, and processing
		 * this bio might require one, we pause until there are some
		 * prepared mappings to process.
		 */
		if (ensure_next_mapping(pool)) {
			spin_lock_irqsave(&pool->lock, flags);
			bio_list_merge(&pool->deferred_bios, &bios);
			spin_unlock_irqrestore(&pool->lock, flags);

			break;
		}
Joe Thornber's avatar
Joe Thornber committed
1450
1451
1452
1453
1454

		if (bio->bi_rw & REQ_DISCARD)
			process_discard(tc, bio);
		else
			process_bio(tc, bio);
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
	}

	/*
	 * If there are any deferred flush bios, we must commit
	 * the metadata before issuing them.
	 */
	bio_list_init(&bios);
	spin_lock_irqsave(&pool->lock, flags);
	bio_list_merge(&bios, &pool->deferred_flush_bios);
	bio_list_init(&pool->deferred_flush_bios);
	spin_unlock_irqrestore(&pool->lock, flags);

1467
	if (bio_list_empty(&bios) && !need_commit_due_to_time(pool))
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
		return;

	r = dm_pool_commit_metadata(pool->pmd);
	if (r) {
		DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
		      __func__, r);
		while ((bio = bio_list_pop(&bios)))
			bio_io_error(bio);
		return;
	}
1478
	pool->last_commit_jiffies = jiffies;
1479
1480
1481
1482
1483
1484
1485
1486
1487

	while ((bio = bio_list_pop(&bios)))
		generic_make_request(bio);
}

static void do_worker(struct work_struct *ws)
{
	struct pool *pool = container_of(ws, struct pool, worker);

Joe Thornber's avatar
Joe Thornber committed
1488
1489
	process_prepared(pool, &pool->prepared_mappings, process_prepared_mapping);
	process_prepared(pool, &pool->prepared_discards, process_prepared_discard);
1490
1491
1492
	process_deferred_bios(pool);
}

1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
/*
 * We want to commit periodically so that not too much
 * unwritten data builds up.
 */
static void do_waker(struct work_struct *ws)
{
	struct pool *pool = container_of(to_delayed_work(ws), struct pool, waker);
	wake_worker(pool);
	queue_delayed_work(pool->wq, &pool->waker, COMMIT_PERIOD);
}

1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
/*----------------------------------------------------------------*/

/*
 * Mapping functions.
 */

/*
 * Called only while mapping a thin bio to hand it over to the workqueue.
 */
static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
{
	unsigned long flags;
	struct pool *pool = tc->pool;

	spin_lock_irqsave(&pool->lock, flags);
	bio_list_add(&pool->deferred_bios, bio);
	spin_unlock_irqrestore(&pool->lock, flags);

	wake_worker(pool);
}

1525
1526
1527
1528
1529
1530
1531
static struct endio_hook *thin_hook_bio(struct thin_c *tc, struct bio *bio)
{
	struct pool *pool = tc->pool;
	struct endio_hook *h = mempool_alloc(pool->endio_hook_pool, GFP_NOIO);

	h->tc = tc;
	h->shared_read_entry = NULL;
Joe Thornber's avatar
Joe Thornber committed
1532
	h->all_io_entry = bio->bi_rw & REQ_DISCARD ? NULL : ds_inc(&pool->all_io_ds);
1533
1534
1535
1536
1537
	h->overwrite_mapping = NULL;

	return h;
}

1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
/*
 * Non-blocking function called from the thin target's map function.
 */
static int thin_bio_map(struct dm_target *ti, struct bio *bio,
			union map_info *map_context)
{
	int r;
	struct thin_c *tc = ti->private;
	dm_block_t block = get_bio_block(tc, bio);
	struct dm_thin_device *td = tc->td;
	struct dm_thin_lookup_result result;

1550
	map_context->ptr = thin_hook_bio(tc, bio);
Joe Thornber's avatar
Joe Thornber committed
1551
	if (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA)) {
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
		thin_defer_bio(tc, bio);
		return DM_MAPIO_SUBMITTED;
	}

	r = dm_thin_find_block(td, block, 0, &result);

	/*
	 * Note that we defer readahead too.
	 */
	switch (r) {
	case 0:
		if (unlikely(result.shared)) {
			/*
			 * We have a race condition here between the
			 * result.shared value returned by the lookup and
			 * snapshot creation, which may cause new
			 * sharing.
			 *
			 * To avoid this always quiesce the origin before
			 * taking the snap.  You want to do this anyway to
			 * ensure a consistent application view
			 * (i.e. lockfs).
			 *
			 * More distant ancestors are irrelevant. The
			 * shared flag will be set in their case.
			 */
			thin_defer_bio(tc, bio);
			r = DM_MAPIO_SUBMITTED;
		} else {
			remap(tc, bio, result.block);
			r = DM_MAPIO_REMAPPED;
		}
		break;

	case -ENODATA:
		/*
		 * In future, the failed dm_thin_find_block above could
		 * provide the hint to load the metadata into cache.
		 */
	case -EWOULDBLOCK:
		thin_defer_bio(tc, bio);
		r = DM_MAPIO_SUBMITTED;
		break;
	}

	return r;
}

static int pool_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
{
	int r;
	unsigned long flags;
	struct pool_c *pt = container_of(cb, struct pool_c, callbacks);

	spin_lock_irqsave(&pt->pool->lock, flags);
	r = !bio_list_empty(&pt->pool->retry_on_resume_list);
	spin_unlock_irqrestore(&pt->pool->lock, flags);

	if (!r) {
		struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
		r = bdi_congested(&q->backing_dev_info, bdi_bits);
	}

	return r;
}

static void __requeue_bios(struct pool *pool)
{
	bio_list_merge(&pool->deferred_bios, &pool->retry_on_resume_list);
	bio_list_init(&pool->retry_on_resume_list);
}

/*----------------------------------------------------------------
 * Binding of control targets to a pool object
 *--------------------------------------------------------------*/
static int bind_control_target(struct pool *pool, struct dm_target *ti)
{
	struct pool_c *pt = ti->private;

	pool->ti = ti;
	pool->low_water_blocks = pt->low_water_blocks;
1633
	pool->pf = pt->pf;
1634

1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
	/*
	 * If discard_passdown was enabled verify that the data device
	 * supports discards.  Disable discard_passdown if not; otherwise
	 * -EOPNOTSUPP will be returned.
	 */
	if (pt->pf.discard_passdown) {
		struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
		if (!q || !blk_queue_discard(q)) {
			char buf[BDEVNAME_SIZE];
			DMWARN("Discard unsupported by data device (%s): Disabling discard passdown.",
			       bdevname(pt->data_dev->bdev, buf));
			pool->pf.discard_passdown = 0;
		}
	}

1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
	return 0;
}

static void unbind_control_target(struct pool *pool, struct dm_target *ti)
{
	if (pool->ti == ti)
		pool->ti = NULL;
}

/*----------------------------------------------------------------
 * Pool creation
 *--------------------------------------------------------------*/
1662
1663
1664
1665
1666
1667
1668
1669
/* Initialize pool features. */
static void pool_features_init(struct pool_features *pf)
{
	pf->zero_new_blocks = 1;
	pf->discard_enabled = 1;
	pf->discard_passdown = 1;
}

1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
static void __pool_destroy(struct pool *pool)
{
	__pool_table_remove(pool);

	if (dm_pool_metadata_close(pool->pmd) < 0)
		DMWARN("%s: dm_pool_metadata_close() failed.", __func__);

	prison_destroy(pool->prison);
	dm_kcopyd_client_destroy(pool->copier);

	if (pool->wq)
		destroy_workqueue(pool->wq);

	if (pool->next_mapping)
		mempool_free(pool->next_mapping, pool->mapping_pool);
	mempool_destroy(pool->mapping_pool);
	mempool_destroy(pool->endio_hook_pool);
	kfree(pool);
}

static struct pool *pool_create(struct mapped_device *pool_md,
				struct block_device *metadata_dev,
				unsigned long block_size, char **error)
{
	int r;
	void *err_p;
	struct pool *pool;
	struct dm_pool_metadata *pmd;

	pmd = dm_pool_metadata_open(metadata_dev, block_size);
	if (IS_ERR(pmd)) {
		*error = "Error creating metadata object";
		return (struct pool *)pmd;
	}

	pool = kmalloc(sizeof(*pool), GFP_KERNEL);
	if (!pool) {
		*error = "Error allocating memory for pool";
		err_p = ERR_PTR(-ENOMEM);
		goto bad_pool;
	}

	pool->pmd = pmd;
	pool->sectors_per_block = block_size;
	pool->block_shift = ffs(block_size) - 1;
	pool->offset_mask = block_size - 1;
	pool->low_water_blocks = 0;
1717
	pool_features_init(&pool->pf);
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
	pool->prison = prison_create(PRISON_CELLS);
	if (!pool->prison) {
		*error = "Error creating pool's bio prison";
		err_p = ERR_PTR(-ENOMEM);
		goto bad_prison;
	}

	pool->copier = dm_kcopyd_client_create();
	if (IS_ERR(pool->copier)) {
		r = PTR_ERR(pool->copier);
		*error = "Error creating pool's kcopyd client";
		err_p = ERR_PTR(r);
		goto bad_kcopyd_client;
	}

	/*
	 * Create singlethreaded workqueue that will service all devices
	 * that use this metadata.
	 */
	pool->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
	if (!pool->wq) {
		*error = "Error creating pool's workqueue";
		err_p = ERR_PTR(-ENOMEM);
		goto bad_wq;
	}

	INIT_WORK(&pool->worker, do_worker);
1745
	INIT_DELAYED_WORK(&pool->waker, do_waker);
1746
1747
1748
1749
	spin_lock_init(&pool->lock);
	bio_list_init(&pool->deferred_bios);
	bio_list_init(&pool->deferred_flush_bios);
	INIT_LIST_HEAD(&pool->prepared_mappings);
Joe Thornber's avatar
Joe Thornber committed
1750
	INIT_LIST_HEAD(&pool->prepared_discards);
1751
1752
1753
	pool->low_water_triggered = 0;
	pool->no_free_space = 0;
	bio_list_init(&pool->retry_on_resume_list);
1754
	ds_init(&pool->shared_read_ds);
Joe Thornber's avatar
Joe Thornber committed
1755
	ds_init(&pool->all_io_ds);
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773

	pool->next_mapping = NULL;
	pool->mapping_pool =
		mempool_create_kmalloc_pool(MAPPING_POOL_SIZE, sizeof(struct new_mapping));
	if (!pool->mapping_pool) {
		*error = "Error creating pool's mapping mempool";
		err_p = ERR_PTR(-ENOMEM);
		goto bad_mapping_pool;
	}

	pool->endio_hook_pool =
		mempool_create_kmalloc_pool(ENDIO_HOOK_POOL_SIZE, sizeof(struct endio_hook));
	if (!pool->endio_hook_pool) {
		*error = "Error creating pool's endio_hook mempool";
		err_p = ERR_PTR(-ENOMEM);
		goto bad_endio_hook_pool;
	}
	pool->ref_count = 1;
1774
	pool->last_commit_jiffies = jiffies;
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
	pool->pool_md = pool_md;
	pool->md_dev = metadata_dev;
	__pool_table_insert(pool);

	return pool;

bad_endio_hook_pool:
	mempool_destroy(pool->mapping_pool);
bad_mapping_pool:
	destroy_workqueue(pool->wq);
bad_wq:
	dm_kcopyd_client_destroy(pool->copier);
bad_kcopyd_client:
	prison_destroy(pool->prison);
bad_prison:
	kfree(pool);
bad_pool:
	if (dm_pool_metadata_close(pmd))
		DMWARN("%s: dm_pool_metadata_close() failed.", __func__);

	return err_p;
}

static void __pool_inc(struct pool *pool)
{
	BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
	pool->ref_count++;
}

static void __pool_dec(struct pool *pool)
{
	BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
	BUG_ON(!pool->ref_count);
	if (!--pool->ref_count)
		__pool_destroy(pool);
}

static struct pool *__pool_find(struct mapped_device *pool_md,
				struct block_device *metadata_dev,
1814
1815
				unsigned long block_size, char **error,
				int *created)
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
{
	struct pool *pool = __pool_table_lookup_metadata_dev(metadata_dev);

	if (pool) {
		if (pool->pool_md != pool_md)
			return ERR_PTR(-EBUSY);
		__pool_inc(pool);

	} else {
		pool = __pool_table_lookup(pool_md);
		if (pool) {
			if (pool->md_dev != metadata_dev)
				return ERR_PTR(-EINVAL);
			__pool_inc(pool);

1831
		} else {
1832
			pool = pool_create(pool_md, metadata_dev, block_size, error);
1833
1834
			*created = 1;
		}
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
	}

	return pool;
}

/*----------------------------------------------------------------
 * Pool target methods
 *--------------------------------------------------------------*/
static void pool_dtr(struct dm_target *ti)
{
	struct pool_c *pt = ti->private;

	mutex_lock(&dm_thin_pool_table.mutex);

	unbind_control_target(pt->pool, ti);
	__pool_dec(pt->pool);
	dm_put_device(ti, pt->metadata_dev);
	dm_put_device(ti, pt->data_dev);
	kfree(pt);

	mutex_unlock(&dm_thin_pool_table.mutex);
}

static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
			       struct dm_target *ti)
{
	int r;
	unsigned argc;
	const char *arg_name;

	static struct dm_arg _args[] = {
1866
		{0, 3, "Invalid number of pool feature arguments"},
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
	};

	/*
	 * No feature arguments supplied.
	 */
	if (!as->argc)
		return 0;

	r = dm_read_arg_group(_args, as, &argc, &ti->error);
	if (r)
		return -EINVAL;

	while (argc && !r) {
		arg_name = dm_shift_arg(as);
		argc--;

		if (!strcasecmp(arg_name, "skip_block_zeroing")) {
			pf->zero_new_blocks = 0;
			continue;
1886
1887
1888
1889
1890
1891
		} else if (!strcasecmp(arg_name, "ignore_discard")) {
			pf->discard_enabled = 0;
			continue;
		} else if (!strcasecmp(arg_name, "no_discard_passdown")) {
			pf->discard_passdown = 0;
			continue;
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
		}

		ti->error = "Unrecognised pool feature requested";
		r = -EINVAL;
	}

	return r;
}

/*
 * thin-pool <metadata dev> <data dev>
 *	     <data block size (sectors)>
 *	     <low water mark (blocks)>
 *	     [<#feature args> [<arg>]*]
 *
 * Optional feature arguments are:
 *	     skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
1909
1910
 *	     ignore_discard: disable discard
 *	     no_discard_passdown: don't pass discards down to the data device
1911
1912
1913
 */
static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
1914
	int r, pool_created = 0;
1915
1916
1917
1918
1919
1920
1921
1922
1923
	struct pool_c *pt;
	struct pool *pool;
	struct pool_features pf;
	struct dm_arg_set as;
	struct dm_dev *data_dev;
	unsigned long block_size;
	dm_block_t low_water_blocks;
	struct dm_dev *metadata_dev;
	sector_t metadata_dev_size;
1924
	char b[BDEVNAME_SIZE];
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945

	/*
	 * FIXME Remove validation from scope of lock.
	 */
	mutex_lock(&dm_thin_pool_table.mutex);

	if (argc < 4) {
		ti->error = "Invalid argument count";
		r = -EINVAL;
		goto out_unlock;
	}
	as.argc = argc;
	as.argv = argv;

	r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &metadata_dev);
	if (r) {
		ti->error = "Error opening metadata block device";
		goto out_unlock;
	}

	metadata_dev_size = i_size_read(metadata_dev->bdev->bd_inode) >> SECTOR_SHIFT;
1946
1947
1948
	if (metadata_dev_size > THIN_METADATA_MAX_SECTORS_WARNING)
		DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
		       bdevname(metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973

	r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &data_dev);
	if (r) {
		ti->error = "Error getting data device";
		goto out_metadata;
	}

	if (kstrtoul(argv[2], 10, &block_size) || !block_size ||
	    block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
	    block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
	    !is_power_of_2(block_size)) {
		ti->error = "Invalid block size";
		r = -EINVAL;
		goto out;
	}

	if (kstrtoull(argv[3], 10, (unsigned long long *)&low_water_blocks)) {
		ti->error = "Invalid low water mark";
		r = -EINVAL;
		goto out;
	}

	/*
	 * Set default pool features.
	 */
1974
	pool_features_init(&pf);
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987

	dm_consume_args(&as, 4);
	r = parse_pool_features(&as, &pf, ti);
	if (r)
		goto out;

	pt = kzalloc(sizeof(*pt), GFP_KERNEL);
	if (!pt) {
		r = -ENOMEM;
		goto out;
	}

	pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev,
1988
			   block_size, &ti->error, &pool_created);
1989
1990
1991
1992
1993
	if (IS_ERR(pool)) {
		r = PTR_ERR(pool);
		goto out_free_pt;
	}

1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
	/*
	 * 'pool_created' reflects whether this is the first table load.
	 * Top level discard support is not allowed to be changed after
	 * initial load.  This would require a pool reload to trigger thin
	 * device changes.
	 */
	if (!pool_created && pf.discard_enabled != pool->pf.discard_enabled) {
		ti->error = "Discard support cannot be disabled once enabled";
		r = -EINVAL;
		goto out_flags_changed;
	}

2006
2007
2008
2009
2010
	pt->pool = pool;
	pt->ti = ti;
	pt->metadata_dev = metadata_dev;
	pt->data_dev = data_dev;
	pt->low_water_blocks = low_water_blocks;
2011
	pt->pf = pf;
2012
	ti->num_flush_requests = 1;
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
	/*
	 * Only need to enable discards if the pool should pass
	 * them down to the data device.  The thin device's discard
	 * processing will cause mappings to be removed from the btree.
	 */
	if (pf.discard_enabled && pf.discard_passdown) {
		ti->num_discard_requests = 1;
		/*
		 * Setting 'discards_supported' circumvents the normal
		 * stacking of discard limits (this keeps the pool and
		 * thin devices' discard limits consistent).
		 */
		ti->discards_supported = 1;
	}
2027
2028
2029
2030
2031
2032
2033
2034
2035
	ti->private = pt;

	pt->callbacks.congested_fn = pool_is_congested;
	dm_table_add_target_callbacks(ti->table, &pt->callbacks);

	mutex_unlock(&dm_thin_pool_table.mutex);

	return 0;

2036
2037
out_flags_changed:
	__pool_dec(pool);
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
out_free_pt:
	kfree(pt);
out:
	dm_put_device(ti, data_dev);
out_metadata:
	dm_put_device(ti, metadata_dev);
out_unlock:
	mutex_unlock(&dm_thin_pool_table.mutex);

	return r;
}

static int pool_map(struct dm_target *ti, struct bio *bio,
		    union map_info *map_context)
{
	int r;
	struct pool_c *pt = ti->private;
	struct pool *pool = pt->pool;
	unsigned long flags;

	/*
	 * As this is a singleton target, ti->begin is always zero.
	 */
	spin_lock_irqsave(&pool->lock, flags);
	bio->bi_bdev = pt->data_dev->bdev;
	r = DM_MAPIO_REMAPPED;
	spin_unlock_irqrestore(&pool->lock, flags);

	return r;
}

/*
 * Retrieves the number of blocks of the data device from
 * the superblock and compares it to the actual device size,
 * thus resizing the data device in case it has grown.
 *
 * This both copes with opening preallocated data devices in the ctr
 * being followed by a resume
 * -and-
 * calling the resume method individually after userspace has
 * grown the data device in reaction to a table event.
 */
static int pool_preresume(struct dm_target *ti)
{
	int r;
	struct pool_c *pt = ti->private;
	struct pool *pool = pt->pool;
	dm_block_t data_size, sb_data_size;

	/*
	 * Take control of the pool object.
	 */
	r = bind_control_target(pool, ti);
	if (r)
		return r;

	data_size = ti->len >> pool->block_shift;
	r = dm_pool_get_data_dev_size(pool->pmd, &sb_data_size);
	if (r) {
		DMERR("failed to retrieve data device size");
		return r;
	}

	if (data_size < sb_data_size) {
		DMERR("pool target too small, is %llu blocks (expected %llu)",
		      data_size, sb_data_size);
		return -EINVAL;

	} else if (data_size > sb_data_size) {
		r = dm_pool_resize_data_dev(pool->pmd, data_size);
		if (r) {
			DMERR("failed to resize data device");
			return r;
		}

		r = dm_pool_commit_metadata(pool->pmd);
		if (r) {
			DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
			      __func__, r);
			return r;
		}
	}

	return 0;
}

static void pool_resume(struct dm_target *ti)
{
	struct pool_c *pt = ti->private;
	struct pool *pool = pt->pool;
	unsigned long flags;

	spin_lock_irqsave(&pool->lock, flags);
	pool->low_water_triggered = 0;
	pool->no_free_space = 0;
	__requeue_bios(pool);
	spin_unlock_irqrestore(&pool->lock, flags);

2136
	do_waker(&pool->waker.work);
2137
2138
2139
2140
2141
2142
2143
2144
}

static void pool_postsuspend(struct dm_target *ti)
{
	int r;
	struct pool_c *pt = ti->private;
	struct pool *pool = pt->pool;