summaryrefslogtreecommitdiffstats
path: root/drivers/md/dm-log.c
blob: 6a9261351848ba7e3272de48a51d100345a45a7f (plain)
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
26
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
66
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
118
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
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
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
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
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
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
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
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
678
679
680
681
682
683
684
685
686
687
688
689
690
/*
 * Copyright (C) 2003 Sistina Software
 *
 * This file is released under the LGPL.
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/vmalloc.h>

#include "dm-log.h"
#include "dm-io.h"

#define DM_MSG_PREFIX "mirror log"

static LIST_HEAD(_log_types);
static DEFINE_SPINLOCK(_lock);

int dm_register_dirty_log_type(struct dirty_log_type *type)
{
	spin_lock(&_lock);
	type->use_count = 0;
	list_add(&type->list, &_log_types);
	spin_unlock(&_lock);

	return 0;
}

int dm_unregister_dirty_log_type(struct dirty_log_type *type)
{
	spin_lock(&_lock);

	if (type->use_count)
		DMWARN("Attempt to unregister a log type that is still in use");
	else
		list_del(&type->list);

	spin_unlock(&_lock);

	return 0;
}

static struct dirty_log_type *get_type(const char *type_name)
{
	struct dirty_log_type *type;

	spin_lock(&_lock);
	list_for_each_entry (type, &_log_types, list)
		if (!strcmp(type_name, type->name)) {
			if (!type->use_count && !try_module_get(type->module)){
				spin_unlock(&_lock);
				return NULL;
			}
			type->use_count++;
			spin_unlock(&_lock);
			return type;
		}

	spin_unlock(&_lock);
	return NULL;
}

static void put_type(struct dirty_log_type *type)
{
	spin_lock(&_lock);
	if (!--type->use_count)
		module_put(type->module);
	spin_unlock(&_lock);
}

struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
				      unsigned int argc, char **argv)
{
	struct dirty_log_type *type;
	struct dirty_log *log;

	log = kmalloc(sizeof(*log), GFP_KERNEL);
	if (!log)
		return NULL;

	type = get_type(type_name);
	if (!type) {
		kfree(log);
		return NULL;
	}

	log->type = type;
	if (type->ctr(log, ti, argc, argv)) {
		kfree(log);
		put_type(type);
		return NULL;
	}

	return log;
}

void dm_destroy_dirty_log(struct dirty_log *log)
{
	log->type->dtr(log);
	put_type(log->type);
	kfree(log);
}

/*-----------------------------------------------------------------
 * Persistent and core logs share a lot of their implementation.
 * FIXME: need a reload method to be called from a resume
 *---------------------------------------------------------------*/
/*
 * Magic for persistent mirrors: "MiRr"
 */
#define MIRROR_MAGIC 0x4D695272

/*
 * The on-disk version of the metadata.
 */
#define MIRROR_DISK_VERSION 2
#define LOG_OFFSET 2

struct log_header {
	uint32_t magic;

	/*
	 * Simple, incrementing version. no backward
	 * compatibility.
	 */
	uint32_t version;
	sector_t nr_regions;
};

struct log_c {
	struct dm_target *ti;
	int touched;
	uint32_t region_size;
	unsigned int region_count;
	region_t sync_count;

	unsigned bitset_uint32_count;
	uint32_t *clean_bits;
	uint32_t *sync_bits;
	uint32_t *recovering_bits;	/* FIXME: this seems excessive */

	int sync_search;

	/* Resync flag */
	enum sync {
		DEFAULTSYNC,	/* Synchronize if necessary */
		NOSYNC,		/* Devices known to be already in sync */
		FORCESYNC,	/* Force a sync to happen */
	} sync;

	/*
	 * Disk log fields
	 */
	struct dm_dev *log_dev;
	struct log_header header;

	struct io_region header_location;
	struct log_header *disk_header;
};

/*
 * The touched member needs to be updated every time we access
 * one of the bitsets.
 */
static  inline int log_test_bit(uint32_t *bs, unsigned bit)
{
	return ext2_test_bit(bit, (unsigned long *) bs) ? 1 : 0;
}

static inline void log_set_bit(struct log_c *l,
			       uint32_t *bs, unsigned bit)
{
	ext2_set_bit(bit, (unsigned long *) bs);
	l->touched = 1;
}

static inline void log_clear_bit(struct log_c *l,
				 uint32_t *bs, unsigned bit)
{
	ext2_clear_bit(bit, (unsigned long *) bs);
	l->touched = 1;
}

/*----------------------------------------------------------------
 * Header IO
 *--------------------------------------------------------------*/
static void header_to_disk(struct log_header *core, struct log_header *disk)
{
	disk->magic = cpu_to_le32(core->magic);
	disk->version = cpu_to_le32(core->version);
	disk->nr_regions = cpu_to_le64(core->nr_regions);
}

static void header_from_disk(struct log_header *core, struct log_header *disk)
{
	core->magic = le32_to_cpu(disk->magic);
	core->version = le32_to_cpu(disk->version);
	core->nr_regions = le64_to_cpu(disk->nr_regions);
}

static int read_header(struct log_c *log)
{
	int r;
	unsigned long ebits;

	r = dm_io_sync_vm(1, &log->header_location, READ,
			  log->disk_header, &ebits);
	if (r)
		return r;

	header_from_disk(&log->header, log->disk_header);

	/* New log required? */
	if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
		log->header.magic = MIRROR_MAGIC;
		log->header.version = MIRROR_DISK_VERSION;
		log->header.nr_regions = 0;
	}

#ifdef __LITTLE_ENDIAN
	if (log->header.version == 1)
		log->header.version = 2;
#endif

	if (log->header.version != MIRROR_DISK_VERSION) {
		DMWARN("incompatible disk log version");
		return -EINVAL;
	}

	return 0;
}

static inline int write_header(struct log_c *log)
{
	unsigned long ebits;

	header_to_disk(&log->header, log->disk_header);
	return dm_io_sync_vm(1, &log->header_location, WRITE,
			     log->disk_header, &ebits);
}

/*----------------------------------------------------------------
 * core log constructor/destructor
 *
 * argv contains region_size followed optionally by [no]sync
 *--------------------------------------------------------------*/
#define BYTE_SHIFT 3
static int create_log_context(struct dirty_log *log, struct dm_target *ti,
			      unsigned int argc, char **argv,
			      struct dm_dev *dev)
{
	enum sync sync = DEFAULTSYNC;

	struct log_c *lc;
	uint32_t region_size;
	unsigned int region_count;
	size_t bitset_size, buf_size;

	if (argc < 1 || argc > 2) {
		DMWARN("wrong number of arguments to mirror log");
		return -EINVAL;
	}

	if (argc > 1) {
		if (!strcmp(argv[1], "sync"))
			sync = FORCESYNC;
		else if (!strcmp(argv[1], "nosync"))
			sync = NOSYNC;
		else {
			DMWARN("unrecognised sync argument to mirror log: %s",
			       argv[1]);
			return -EINVAL;
		}
	}

	if (sscanf(argv[0], "%u", &region_size) != 1) {
		DMWARN("invalid region size string");
		return -EINVAL;
	}

	region_count = dm_sector_div_up(ti->len, region_size);

	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
	if (!lc) {
		DMWARN("couldn't allocate core log");
		return -ENOMEM;
	}

	lc->ti = ti;
	lc->touched = 0;
	lc->region_size = region_size;
	lc->region_count = region_count;
	lc->sync = sync;

	/*
	 * Work out how many "unsigned long"s we need to hold the bitset.
	 */
	bitset_size = dm_round_up(region_count,
				  sizeof(*lc->clean_bits) << BYTE_SHIFT);
	bitset_size >>= BYTE_SHIFT;

	lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits);

	/*
	 * Disk log?
	 */
	if (!dev) {
		lc->clean_bits = vmalloc(bitset_size);
		if (!lc->clean_bits) {
			DMWARN("couldn't allocate clean bitset");
			kfree(lc);
			return -ENOMEM;
		}
		lc->disk_header = NULL;
	} else {
		lc->log_dev = dev;
		lc->header_location.bdev = lc->log_dev->bdev;
		lc->header_location.sector = 0;

		/*
		 * Buffer holds both header and bitset.
		 */
		buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
				       bitset_size, ti->limits.hardsect_size);
		lc->header_location.count = buf_size >> SECTOR_SHIFT;

		lc->disk_header = vmalloc(buf_size);
		if (!lc->disk_header) {
			DMWARN("couldn't allocate disk log buffer");
			kfree(lc);
			return -ENOMEM;
		}

		lc->clean_bits = (void *)lc->disk_header +
				 (LOG_OFFSET << SECTOR_SHIFT);
	}

	memset(lc->clean_bits, -1, bitset_size);

	lc->sync_bits = vmalloc(bitset_size);
	if (!lc->sync_bits) {
		DMWARN("couldn't allocate sync bitset");
		if (!dev)
			vfree(lc->clean_bits);
		vfree(lc->disk_header);
		kfree(lc);
		return -ENOMEM;
	}
	memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
	lc->sync_count = (sync == NOSYNC) ? region_count : 0;

	lc->recovering_bits = vmalloc(bitset_size);
	if (!lc->recovering_bits) {
		DMWARN("couldn't allocate sync bitset");
		vfree(lc->sync_bits);
		if (!dev)
			vfree(lc->clean_bits);
		vfree(lc->disk_header);
		kfree(lc);
		return -ENOMEM;
	}
	memset(lc->recovering_bits, 0, bitset_size);
	lc->sync_search = 0;
	log->context = lc;

	return 0;
}

static int core_ctr(struct dirty_log *log, struct dm_target *ti,
		    unsigned int argc, char **argv)
{
	return create_log_context(log, ti, argc, argv, NULL);
}

static void destroy_log_context(struct log_c *lc)
{
	vfree(lc->sync_bits);
	vfree(lc->recovering_bits);
	kfree(lc);
}

static void core_dtr(struct dirty_log *log)
{
	struct log_c *lc = (struct log_c *) log->context;

	vfree(lc->clean_bits);
	destroy_log_context(lc);
}

/*----------------------------------------------------------------
 * disk log constructor/destructor
 *
 * argv contains log_device region_size followed optionally by [no]sync
 *--------------------------------------------------------------*/
static int disk_ctr(struct dirty_log *log, struct dm_target *ti,
		    unsigned int argc, char **argv)
{
	int r;
	struct dm_dev *dev;

	if (argc < 2 || argc > 3) {
		DMWARN("wrong number of arguments to disk mirror log");
		return -EINVAL;
	}

	r = dm_get_device(ti, argv[0], 0, 0 /* FIXME */,
			  FMODE_READ | FMODE_WRITE, &dev);
	if (r)
		return r;

	r = create_log_context(log, ti, argc - 1, argv + 1, dev);
	if (r) {
		dm_put_device(ti, dev);
		return r;
	}

	return 0;
}

static void disk_dtr(struct dirty_log *log)
{
	struct log_c *lc = (struct log_c *) log->context;

	dm_put_device(lc->ti, lc->log_dev);
	vfree(lc->disk_header);
	destroy_log_context(lc);
}

static int count_bits32(uint32_t *addr, unsigned size)
{
	int count = 0, i;

	for (i = 0; i < size; i++) {
		count += hweight32(*(addr+i));
	}
	return count;
}

static int disk_resume(struct dirty_log *log)
{
	int r;
	unsigned i;
	struct log_c *lc = (struct log_c *) log->context;
	size_t size = lc->bitset_uint32_count * sizeof(uint32_t);

	/* read the disk header */
	r = read_header(lc);
	if (r)
		return r;

	/* set or clear any new bits -- device has grown */
	if (lc->sync == NOSYNC)
		for (i = lc->header.nr_regions; i < lc->region_count; i++)
			/* FIXME: amazingly inefficient */
			log_set_bit(lc, lc->clean_bits, i);
	else
		for (i = lc->header.nr_regions; i < lc->region_count; i++)
			/* FIXME: amazingly inefficient */
			log_clear_bit(lc, lc->clean_bits, i);

	/* clear any old bits -- device has shrunk */
	for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
		log_clear_bit(lc, lc->clean_bits, i);

	/* copy clean across to sync */
	memcpy(lc->sync_bits, lc->clean_bits, size);
	lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
	lc->sync_search = 0;

	/* set the correct number of regions in the header */
	lc->header.nr_regions = lc->region_count;

	/* write the new header */
	return write_header(lc);
}

static uint32_t core_get_region_size(struct dirty_log *log)
{
	struct log_c *lc = (struct log_c *) log->context;
	return lc->region_size;
}

static int core_resume(struct dirty_log *log)
{
	struct log_c *lc = (struct log_c *) log->context;
	lc->sync_search = 0;
	return 0;
}

static int core_is_clean(struct dirty_log *log, region_t region)
{
	struct log_c *lc = (struct log_c *) log->context;
	return log_test_bit(lc->clean_bits, region);
}

static int core_in_sync(struct dirty_log *log, region_t region, int block)
{
	struct log_c *lc = (struct log_c *) log->context;
	return log_test_bit(lc->sync_bits, region);
}

static int core_flush(struct dirty_log *log)
{
	/* no op */
	return 0;
}

static int disk_flush(struct dirty_log *log)
{
	int r;
	struct log_c *lc = (struct log_c *) log->context;

	/* only write if the log has changed */
	if (!lc->touched)
		return 0;

	r = write_header(lc);
	if (!r)
		lc->touched = 0;

	return r;
}

static void core_mark_region(struct dirty_log *log, region_t region)
{
	struct log_c *lc = (struct log_c *) log->context;
	log_clear_bit(lc, lc->clean_bits, region);
}

static void core_clear_region(struct dirty_log *log, region_t region)
{
	struct log_c *lc = (struct log_c *) log->context;
	log_set_bit(lc, lc->clean_bits, region);
}

static int core_get_resync_work(struct dirty_log *log, region_t *region)
{
	struct log_c *lc = (struct log_c *) log->context;

	if (lc->sync_search >= lc->region_count)
		return 0;

	do {
		*region = ext2_find_next_zero_bit(
					     (unsigned long *) lc->sync_bits,
					     lc->region_count,
					     lc->sync_search);
		lc->sync_search = *region + 1;

		if (*region >= lc->region_count)
			return 0;

	} while (log_test_bit(lc->recovering_bits, *region));

	log_set_bit(lc, lc->recovering_bits, *region);
	return 1;
}

static void core_set_region_sync(struct dirty_log *log, region_t region,
				 int in_sync)
{
	struct log_c *lc = (struct log_c *) log->context;

	log_clear_bit(lc, lc->recovering_bits, region);
	if (in_sync) {
		log_set_bit(lc, lc->sync_bits, region);
                lc->sync_count++;
        } else if (log_test_bit(lc->sync_bits, region)) {
		lc->sync_count--;
		log_clear_bit(lc, lc->sync_bits, region);
	}
}

static region_t core_get_sync_count(struct dirty_log *log)
{
        struct log_c *lc = (struct log_c *) log->context;

        return lc->sync_count;
}

#define	DMEMIT_SYNC \
	if (lc->sync != DEFAULTSYNC) \
		DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")

static int core_status(struct dirty_log *log, status_type_t status,
		       char *result, unsigned int maxlen)
{
	int sz = 0;
	struct log_c *lc = log->context;

	switch(status) {
	case STATUSTYPE_INFO:
		break;

	case STATUSTYPE_TABLE:
		DMEMIT("%s %u %u ", log->type->name,
		       lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
		DMEMIT_SYNC;
	}

	return sz;
}

static int disk_status(struct dirty_log *log, status_type_t status,
		       char *result, unsigned int maxlen)
{
	int sz = 0;
	char buffer[16];
	struct log_c *lc = log->context;

	switch(status) {
	case STATUSTYPE_INFO:
		break;

	case STATUSTYPE_TABLE:
		format_dev_t(buffer, lc->log_dev->bdev->bd_dev);
		DMEMIT("%s %u %s %u ", log->type->name,
		       lc->sync == DEFAULTSYNC ? 2 : 3, buffer,
		       lc->region_size);
		DMEMIT_SYNC;
	}

	return sz;
}

static struct dirty_log_type _core_type = {
	.name = "core",
	.module = THIS_MODULE,
	.ctr = core_ctr,
	.dtr = core_dtr,
	.resume = core_resume,
	.get_region_size = core_get_region_size,
	.is_clean = core_is_clean,
	.in_sync = core_in_sync,
	.flush = core_flush,
	.mark_region = core_mark_region,
	.clear_region = core_clear_region,
	.get_resync_work = core_get_resync_work,
	.set_region_sync = core_set_region_sync,
	.get_sync_count = core_get_sync_count,
	.status = core_status,
};

static struct dirty_log_type _disk_type = {
	.name = "disk",
	.module = THIS_MODULE,
	.ctr = disk_ctr,
	.dtr = disk_dtr,
	.suspend = disk_flush,
	.resume = disk_resume,
	.get_region_size = core_get_region_size,
	.is_clean = core_is_clean,
	.in_sync = core_in_sync,
	.flush = disk_flush,
	.mark_region = core_mark_region,
	.clear_region = core_clear_region,
	.get_resync_work = core_get_resync_work,
	.set_region_sync = core_set_region_sync,
	.get_sync_count = core_get_sync_count,
	.status = disk_status,
};

int __init dm_dirty_log_init(void)
{
	int r;

	r = dm_register_dirty_log_type(&_core_type);
	if (r)
		DMWARN("couldn't register core log");

	r = dm_register_dirty_log_type(&_disk_type);
	if (r) {
		DMWARN("couldn't register disk type");
		dm_unregister_dirty_log_type(&_core_type);
	}

	return r;
}

void dm_dirty_log_exit(void)
{
	dm_unregister_dirty_log_type(&_disk_type);
	dm_unregister_dirty_log_type(&_core_type);
}

EXPORT_SYMBOL(dm_register_dirty_log_type);
EXPORT_SYMBOL(dm_unregister_dirty_log_type);
EXPORT_SYMBOL(dm_create_dirty_log);
EXPORT_SYMBOL(dm_destroy_dirty_log);