aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/md/dm-raid.c
blob: b9e1e15ef11cb3d45f53b8c06a0dd6b709fa1164 (plain) (blame)
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
691
692
693
694
695
696
697
/*
 * Copyright (C) 2010-2011 Neil Brown
 * Copyright (C) 2010-2011 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the GPL.
 */

#include <linux/slab.h>

#include "md.h"
#include "raid5.h"
#include "dm.h"
#include "bitmap.h"

#define DM_MSG_PREFIX "raid"

/*
 * If the MD doesn't support MD_SYNC_STATE_FORCED yet, then
 * make it so the flag doesn't set anything.
 */
#ifndef MD_SYNC_STATE_FORCED
#define MD_SYNC_STATE_FORCED 0
#endif

struct raid_dev {
	/*
	 * Two DM devices, one to hold metadata and one to hold the
	 * actual data/parity.  The reason for this is to not confuse
	 * ti->len and give more flexibility in altering size and
	 * characteristics.
	 *
	 * While it is possible for this device to be associated
	 * with a different physical device than the data_dev, it
	 * is intended for it to be the same.
	 *    |--------- Physical Device ---------|
	 *    |- meta_dev -|------ data_dev ------|
	 */
	struct dm_dev *meta_dev;
	struct dm_dev *data_dev;
	struct mdk_rdev_s rdev;
};

/*
 * Flags for rs->print_flags field.
 */
#define DMPF_DAEMON_SLEEP      0x1
#define DMPF_MAX_WRITE_BEHIND  0x2
#define DMPF_SYNC              0x4
#define DMPF_NOSYNC            0x8
#define DMPF_STRIPE_CACHE      0x10
#define DMPF_MIN_RECOVERY_RATE 0x20
#define DMPF_MAX_RECOVERY_RATE 0x40

struct raid_set {
	struct dm_target *ti;

	uint64_t print_flags;

	struct mddev_s md;
	struct raid_type *raid_type;
	struct dm_target_callbacks callbacks;

	struct raid_dev dev[0];
};

/* Supported raid types and properties. */
static struct raid_type {
	const char *name;		/* RAID algorithm. */
	const char *descr;		/* Descriptor text for logging. */
	const unsigned parity_devs;	/* # of parity devices. */
	const unsigned minimal_devs;	/* minimal # of devices in set. */
	const unsigned level;		/* RAID level. */
	const unsigned algorithm;	/* RAID algorithm. */
} raid_types[] = {
	{"raid4",    "RAID4 (dedicated parity disk)",	1, 2, 5, ALGORITHM_PARITY_0},
	{"raid5_la", "RAID5 (left asymmetric)",		1, 2, 5, ALGORITHM_LEFT_ASYMMETRIC},
	{"raid5_ra", "RAID5 (right asymmetric)",	1, 2, 5, ALGORITHM_RIGHT_ASYMMETRIC},
	{"raid5_ls", "RAID5 (left symmetric)",		1, 2, 5, ALGORITHM_LEFT_SYMMETRIC},
	{"raid5_rs", "RAID5 (right symmetric)",		1, 2, 5, ALGORITHM_RIGHT_SYMMETRIC},
	{"raid6_zr", "RAID6 (zero restart)",		2, 4, 6, ALGORITHM_ROTATING_ZERO_RESTART},
	{"raid6_nr", "RAID6 (N restart)",		2, 4, 6, ALGORITHM_ROTATING_N_RESTART},
	{"raid6_nc", "RAID6 (N continue)",		2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE}
};

static struct raid_type *get_raid_type(char *name)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(raid_types); i++)
		if (!strcmp(raid_types[i].name, name))
			return &raid_types[i];

	return NULL;
}

static struct raid_set *context_alloc(struct dm_target *ti, struct raid_type *raid_type, unsigned raid_devs)
{
	unsigned i;
	struct raid_set *rs;
	sector_t sectors_per_dev;

	if (raid_devs <= raid_type->parity_devs) {
		ti->error = "Insufficient number of devices";
		return ERR_PTR(-EINVAL);
	}

	sectors_per_dev = ti->len;
	if (sector_div(sectors_per_dev, (raid_devs - raid_type->parity_devs))) {
		ti->error = "Target length not divisible by number of data devices";
		return ERR_PTR(-EINVAL);
	}

	rs = kzalloc(sizeof(*rs) + raid_devs * sizeof(rs->dev[0]), GFP_KERNEL);
	if (!rs) {
		ti->error = "Cannot allocate raid context";
		return ERR_PTR(-ENOMEM);
	}

	mddev_init(&rs->md);

	rs->ti = ti;
	rs->raid_type = raid_type;
	rs->md.raid_disks = raid_devs;
	rs->md.level = raid_type->level;
	rs->md.new_level = rs->md.level;
	rs->md.dev_sectors = sectors_per_dev;
	rs->md.layout = raid_type->algorithm;
	rs->md.new_layout = rs->md.layout;
	rs->md.delta_disks = 0;
	rs->md.recovery_cp = 0;

	for (i = 0; i < raid_devs; i++)
		md_rdev_init(&rs->dev[i].rdev);

	/*
	 * Remaining items to be initialized by further RAID params:
	 *  rs->md.persistent
	 *  rs->md.external
	 *  rs->md.chunk_sectors
	 *  rs->md.new_chunk_sectors
	 */

	return rs;
}

static void context_free(struct raid_set *rs)
{
	int i;

	for (i = 0; i < rs->md.raid_disks; i++)
		if (rs->dev[i].data_dev)
			dm_put_device(rs->ti, rs->dev[i].data_dev);

	kfree(rs);
}

/*
 * For every device we have two words
 *  <meta_dev>: meta device name or '-' if missing
 *  <data_dev>: data device name or '-' if missing
 *
 * This code parses those words.
 */
static int dev_parms(struct raid_set *rs, char **argv)
{
	int i;
	int rebuild = 0;
	int metadata_available = 0;
	int ret = 0;

	for (i = 0; i < rs->md.raid_disks; i++, argv += 2) {
		rs->dev[i].rdev.raid_disk = i;

		rs->dev[i].meta_dev = NULL;
		rs->dev[i].data_dev = NULL;

		/*
		 * There are no offsets, since there is a separate device
		 * for data and metadata.
		 */
		rs->dev[i].rdev.data_offset = 0;
		rs->dev[i].rdev.mddev = &rs->md;

		if (strcmp(argv[0], "-")) {
			rs->ti->error = "Metadata devices not supported";
			return -EINVAL;
		}

		if (!strcmp(argv[1], "-")) {
			if (!test_bit(In_sync, &rs->dev[i].rdev.flags) &&
			    (!rs->dev[i].rdev.recovery_offset)) {
				rs->ti->error = "Drive designated for rebuild not specified";
				return -EINVAL;
			}

			continue;
		}

		ret = dm_get_device(rs->ti, argv[1],
				    dm_table_get_mode(rs->ti->table),
				    &rs->dev[i].data_dev);
		if (ret) {
			rs->ti->error = "RAID device lookup failure";
			return ret;
		}

		rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev;
		list_add(&rs->dev[i].rdev.same_set, &rs->md.disks);
		if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
			rebuild++;
	}

	if (metadata_available) {
		rs->md.external = 0;
		rs->md.persistent = 1;
		rs->md.major_version = 2;
	} else if (rebuild && !rs->md.recovery_cp) {
		/*
		 * Without metadata, we will not be able to tell if the array
		 * is in-sync or not - we must assume it is not.  Therefore,
		 * it is impossible to rebuild a drive.
		 *
		 * Even if there is metadata, the on-disk information may
		 * indicate that the array is not in-sync and it will then
		 * fail at that time.
		 *
		 * User could specify 'nosync' option if desperate.
		 */
		DMERR("Unable to rebuild drive while array is not in-sync");
		rs->ti->error = "RAID device lookup failure";
		return -EINVAL;
	}

	return 0;
}

/*
 * Possible arguments are...
 * RAID456:
 *	<chunk_size> [optional_args]
 *
 * Optional args:
 *    [[no]sync]			Force or prevent recovery of the entire array
 *    [rebuild <idx>]			Rebuild the drive indicated by the index
 *    [daemon_sleep <ms>]		Time between bitmap daemon work to clear bits
 *    [min_recovery_rate <kB/sec/disk>]	Throttle RAID initialization
 *    [max_recovery_rate <kB/sec/disk>]	Throttle RAID initialization
 *    [max_write_behind <sectors>]	See '-write-behind=' (man mdadm)
 *    [stripe_cache <sectors>]		Stripe cache size for higher RAIDs
 */
static int parse_raid_params(struct raid_set *rs, char **argv,
			     unsigned num_raid_params)
{
	unsigned i, rebuild_cnt = 0;
	unsigned long value;
	char *key;

	/*
	 * First, parse the in-order required arguments
	 */
	if ((strict_strtoul(argv[0], 10, &value) < 0) ||
	    !is_power_of_2(value) || (value < 8)) {
		rs->ti->error = "Bad chunk size";
		return -EINVAL;
	}

	rs->md.new_chunk_sectors = rs->md.chunk_sectors = value;
	argv++;
	num_raid_params--;

	/*
	 * Second, parse the unordered optional arguments
	 */
	for (i = 0; i < rs->md.raid_disks; i++)
		set_bit(In_sync, &rs->dev[i].rdev.flags);

	for (i = 0; i < num_raid_params; i++) {
		if (!strcmp(argv[i], "nosync")) {
			rs->md.recovery_cp = MaxSector;
			rs->print_flags |= DMPF_NOSYNC;
			rs->md.flags |= MD_SYNC_STATE_FORCED;
			continue;
		}
		if (!strcmp(argv[i], "sync")) {
			rs->md.recovery_cp = 0;
			rs->print_flags |= DMPF_SYNC;
			rs->md.flags |= MD_SYNC_STATE_FORCED;
			continue;
		}

		/* The rest of the optional arguments come in key/value pairs */
		if ((i + 1) >= num_raid_params) {
			rs->ti->error = "Wrong number of raid parameters given";
			return -EINVAL;
		}

		key = argv[i++];
		if (strict_strtoul(argv[i], 10, &value) < 0) {
			rs->ti->error = "Bad numerical argument given in raid params";
			return -EINVAL;
		}

		if (!strcmp(key, "rebuild")) {
			if (++rebuild_cnt > rs->raid_type->parity_devs) {
				rs->ti->error = "Too many rebuild drives given";
				return -EINVAL;
			}
			if (value > rs->md.raid_disks) {
				rs->ti->error = "Invalid rebuild index given";
				return -EINVAL;
			}
			clear_bit(In_sync, &rs->dev[value].rdev.flags);
			rs->dev[value].rdev.recovery_offset = 0;
		} else if (!strcmp(key, "max_write_behind")) {
			rs->print_flags |= DMPF_MAX_WRITE_BEHIND;

			/*
			 * In device-mapper, we specify things in sectors, but
			 * MD records this value in kB
			 */
			value /= 2;
			if (value > COUNTER_MAX) {
				rs->ti->error = "Max write-behind limit out of range";
				return -EINVAL;
			}
			rs->md.bitmap_info.max_write_behind = value;
		} else if (!strcmp(key, "daemon_sleep")) {
			rs->print_flags |= DMPF_DAEMON_SLEEP;
			if (!value || (value > MAX_SCHEDULE_TIMEOUT)) {
				rs->ti->error = "daemon sleep period out of range";
				return -EINVAL;
			}
			rs->md.bitmap_info.daemon_sleep = value;
		} else if (!strcmp(key, "stripe_cache")) {
			rs->print_flags |= DMPF_STRIPE_CACHE;

			/*
			 * In device-mapper, we specify things in sectors, but
			 * MD records this value in kB
			 */
			value /= 2;

			if (rs->raid_type->level < 5) {
				rs->ti->error = "Inappropriate argument: stripe_cache";
				return -EINVAL;
			}
			if (raid5_set_cache_size(&rs->md, (int)value)) {
				rs->ti->error = "Bad stripe_cache size";
				return -EINVAL;
			}
		} else if (!strcmp(key, "min_recovery_rate")) {
			rs->print_flags |= DMPF_MIN_RECOVERY_RATE;
			if (value > INT_MAX) {
				rs->ti->error = "min_recovery_rate out of range";
				return -EINVAL;
			}
			rs->md.sync_speed_min = (int)value;
		} else if (!strcmp(key, "max_recovery_rate")) {
			rs->print_flags |= DMPF_MAX_RECOVERY_RATE;
			if (value > INT_MAX) {
				rs->ti->error = "max_recovery_rate out of range";
				return -EINVAL;
			}
			rs->md.sync_speed_max = (int)value;
		} else {
			DMERR("Unable to parse RAID parameter: %s", key);
			rs->ti->error = "Unable to parse RAID parameters";
			return -EINVAL;
		}
	}

	/* Assume there are no metadata devices until the drives are parsed */
	rs->md.persistent = 0;
	rs->md.external = 1;

	return 0;
}

static void do_table_event(struct work_struct *ws)
{
	struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);

	dm_table_event(rs->ti->table);
}

static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
{
	struct raid_set *rs = container_of(cb, struct raid_set, callbacks);

	return md_raid5_congested(&rs->md, bits);
}

static void raid_unplug(struct dm_target_callbacks *cb)
{
	struct raid_set *rs = container_of(cb, struct raid_set, callbacks);

	md_raid5_unplug_device(rs->md.private);
}

/*
 * Construct a RAID4/5/6 mapping:
 * Args:
 *	<raid_type> <#raid_params> <raid_params>		\
 *	<#raid_devs> { <meta_dev1> <dev1> .. <meta_devN> <devN> }
 *
 * ** metadata devices are not supported yet, use '-' instead **
 *
 * <raid_params> varies by <raid_type>.  See 'parse_raid_params' for
 * details on possible <raid_params>.
 */
static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
	int ret;
	struct raid_type *rt;
	unsigned long num_raid_params, num_raid_devs;
	struct raid_set *rs = NULL;

	/* Must have at least <raid_type> <#raid_params> */
	if (argc < 2) {
		ti->error = "Too few arguments";
		return -EINVAL;
	}

	/* raid type */
	rt = get_raid_type(argv[0]);
	if (!rt) {
		ti->error = "Unrecognised raid_type";
		return -EINVAL;
	}
	argc--;
	argv++;

	/* number of RAID parameters */
	if (strict_strtoul(argv[0], 10, &num_raid_params) < 0) {
		ti->error = "Cannot understand number of RAID parameters";
		return -EINVAL;
	}
	argc--;
	argv++;

	/* Skip over RAID params for now and find out # of devices */
	if (num_raid_params + 1 > argc) {
		ti->error = "Arguments do not agree with counts given";
		return -EINVAL;
	}

	if ((strict_strtoul(argv[num_raid_params], 10, &num_raid_devs) < 0) ||
	    (num_raid_devs >= INT_MAX)) {
		ti->error = "Cannot understand number of raid devices";
		return -EINVAL;
	}

	rs = context_alloc(ti, rt, (unsigned)num_raid_devs);
	if (IS_ERR(rs))
		return PTR_ERR(rs);

	ret = parse_raid_params(rs, argv, (unsigned)num_raid_params);
	if (ret)
		goto bad;

	ret = -EINVAL;

	argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */
	argv += num_raid_params + 1;

	if (argc != (num_raid_devs * 2)) {
		ti->error = "Supplied RAID devices does not match the count given";
		goto bad;
	}

	ret = dev_parms(rs, argv);
	if (ret)
		goto bad;

	INIT_WORK(&rs->md.event_work, do_table_event);
	ti->split_io = rs->md.chunk_sectors;
	ti->private = rs;

	mutex_lock(&rs->md.reconfig_mutex);
	ret = md_run(&rs->md);
	rs->md.in_sync = 0; /* Assume already marked dirty */
	mutex_unlock(&rs->md.reconfig_mutex);

	if (ret) {
		ti->error = "Fail to run raid array";
		goto bad;
	}

	rs->callbacks.congested_fn = raid_is_congested;
	rs->callbacks.unplug_fn = raid_unplug;
	dm_table_add_target_callbacks(ti->table, &rs->callbacks);

	return 0;

bad:
	context_free(rs);

	return ret;
}

static void raid_dtr(struct dm_target *ti)
{
	struct raid_set *rs = ti->private;

	list_del_init(&rs->callbacks.list);
	md_stop(&rs->md);
	context_free(rs);
}

static int raid_map(struct dm_target *ti, struct bio *bio, union map_info *map_context)
{
	struct raid_set *rs = ti->private;
	mddev_t *mddev = &rs->md;

	mddev->pers->make_request(mddev, bio);

	return DM_MAPIO_SUBMITTED;
}

static int raid_status(struct dm_target *ti, status_type_t type,
		       char *result, unsigned maxlen)
{
	struct raid_set *rs = ti->private;
	unsigned raid_param_cnt = 1; /* at least 1 for chunksize */
	unsigned sz = 0;
	int i;
	sector_t sync;

	switch (type) {
	case STATUSTYPE_INFO:
		DMEMIT("%s %d ", rs->raid_type->name, rs->md.raid_disks);

		for (i = 0; i < rs->md.raid_disks; i++) {
			if (test_bit(Faulty, &rs->dev[i].rdev.flags))
				DMEMIT("D");
			else if (test_bit(In_sync, &rs->dev[i].rdev.flags))
				DMEMIT("A");
			else
				DMEMIT("a");
		}

		if (test_bit(MD_RECOVERY_RUNNING, &rs->md.recovery))
			sync = rs->md.curr_resync_completed;
		else
			sync = rs->md.recovery_cp;

		if (sync > rs->md.resync_max_sectors)
			sync = rs->md.resync_max_sectors;

		DMEMIT(" %llu/%llu",
		       (unsigned long long) sync,
		       (unsigned long long) rs->md.resync_max_sectors);

		break;
	case STATUSTYPE_TABLE:
		/* The string you would use to construct this array */
		for (i = 0; i < rs->md.raid_disks; i++)
			if (rs->dev[i].data_dev &&
			    !test_bit(In_sync, &rs->dev[i].rdev.flags))
				raid_param_cnt++; /* for rebuilds */

		raid_param_cnt += (hweight64(rs->print_flags) * 2);
		if (rs->print_flags & (DMPF_SYNC | DMPF_NOSYNC))
			raid_param_cnt--;

		DMEMIT("%s %u %u", rs->raid_type->name,
		       raid_param_cnt, rs->md.chunk_sectors);

		if ((rs->print_flags & DMPF_SYNC) &&
		    (rs->md.recovery_cp == MaxSector))
			DMEMIT(" sync");
		if (rs->print_flags & DMPF_NOSYNC)
			DMEMIT(" nosync");

		for (i = 0; i < rs->md.raid_disks; i++)
			if (rs->dev[i].data_dev &&
			    !test_bit(In_sync, &rs->dev[i].rdev.flags))
				DMEMIT(" rebuild %u", i);

		if (rs->print_flags & DMPF_DAEMON_SLEEP)
			DMEMIT(" daemon_sleep %lu",
			       rs->md.bitmap_info.daemon_sleep);

		if (rs->print_flags & DMPF_MIN_RECOVERY_RATE)
			DMEMIT(" min_recovery_rate %d", rs->md.sync_speed_min);

		if (rs->print_flags & DMPF_MAX_RECOVERY_RATE)
			DMEMIT(" max_recovery_rate %d", rs->md.sync_speed_max);

		if (rs->print_flags & DMPF_MAX_WRITE_BEHIND)
			DMEMIT(" max_write_behind %lu",
			       rs->md.bitmap_info.max_write_behind);

		if (rs->print_flags & DMPF_STRIPE_CACHE) {
			raid5_conf_t *conf = rs->md.private;

			/* convert from kiB to sectors */
			DMEMIT(" stripe_cache %d",
			       conf ? conf->max_nr_stripes * 2 : 0);
		}

		DMEMIT(" %d", rs->md.raid_disks);
		for (i = 0; i < rs->md.raid_disks; i++) {
			DMEMIT(" -"); /* metadata device */

			if (rs->dev[i].data_dev)
				DMEMIT(" %s", rs->dev[i].data_dev->name);
			else
				DMEMIT(" -");
		}
	}

	return 0;
}

static int raid_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
{
	struct raid_set *rs = ti->private;
	unsigned i;
	int ret = 0;

	for (i = 0; !ret && i < rs->md.raid_disks; i++)
		if (rs->dev[i].data_dev)
			ret = fn(ti,
				 rs->dev[i].data_dev,
				 0, /* No offset on data devs */
				 rs->md.dev_sectors,
				 data);

	return ret;
}

static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
{
	struct raid_set *rs = ti->private;
	unsigned chunk_size = rs->md.chunk_sectors << 9;
	raid5_conf_t *conf = rs->md.private;

	blk_limits_io_min(limits, chunk_size);
	blk_limits_io_opt(limits, chunk_size * (conf->raid_disks - conf->max_degraded));
}

static void raid_presuspend(struct dm_target *ti)
{
	struct raid_set *rs = ti->private;

	md_stop_writes(&rs->md);
}

static void raid_postsuspend(struct dm_target *ti)
{
	struct raid_set *rs = ti->private;

	mddev_suspend(&rs->md);
}

static void raid_resume(struct dm_target *ti)
{
	struct raid_set *rs = ti->private;

	mddev_resume(&rs->md);
}

static struct target_type raid_target = {
	.name = "raid",
	.version = {1, 0, 0},
	.module = THIS_MODULE,
	.ctr = raid_ctr,
	.dtr = raid_dtr,
	.map = raid_map,
	.status = raid_status,
	.iterate_devices = raid_iterate_devices,
	.io_hints = raid_io_hints,
	.presuspend = raid_presuspend,
	.postsuspend = raid_postsuspend,
	.resume = raid_resume,
};

static int __init dm_raid_init(void)
{
	return dm_register_target(&raid_target);
}

static void __exit dm_raid_exit(void)
{
	dm_unregister_target(&raid_target);
}

module_init(dm_raid_init);
module_exit(dm_raid_exit);

MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target");
MODULE_ALIAS("dm-raid4");
MODULE_ALIAS("dm-raid5");
MODULE_ALIAS("dm-raid6");
MODULE_AUTHOR("Neil Brown <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");