summaryrefslogtreecommitdiff
path: root/drivers/mtd/ubi/block.c
blob: b2fb0528c0928bb9515d52a3ad9c762e08ba9bcc (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
691
/*
 * Copyright (c) 2014 Ezequiel Garcia
 * Copyright (c) 2011 Free Electrons
 *
 * Driver parameter handling strongly based on drivers/mtd/ubi/build.c
 *   Copyright (c) International Business Machines Corp., 2006
 *   Copyright (c) Nokia Corporation, 2007
 *   Authors: Artem Bityutskiy, Frank Haverkamp
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 */

/*
 * Read-only block devices on top of UBI volumes
 *
 * A simple implementation to allow a block device to be layered on top of a
 * UBI volume. The implementation is provided by creating a static 1-to-1
 * mapping between the block device and the UBI volume.
 *
 * The addressed byte is obtained from the addressed block sector, which is
 * mapped linearly into the corresponding LEB:
 *
 *   LEB number = addressed byte / LEB size
 *
 * This feature is compiled in the UBI core, and adds a 'block' parameter
 * to allow early creation of block devices on top of UBI volumes. Runtime
 * block creation/removal for UBI volumes is provided through two UBI ioctls:
 * UBI_IOCVOLCRBLK and UBI_IOCVOLRMBLK.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/mtd/ubi.h>
#include <linux/workqueue.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/hdreg.h>
#include <linux/scatterlist.h>
#include <linux/idr.h>
#include <asm/div64.h>

#include "ubi-media.h"
#include "ubi.h"

/* Maximum number of supported devices */
#define UBIBLOCK_MAX_DEVICES 32

/* Maximum length of the 'block=' parameter */
#define UBIBLOCK_PARAM_LEN 63

/* Maximum number of comma-separated items in the 'block=' parameter */
#define UBIBLOCK_PARAM_COUNT 2

struct ubiblock_param {
	int ubi_num;
	int vol_id;
	char name[UBIBLOCK_PARAM_LEN+1];
};

struct ubiblock_pdu {
	struct work_struct work;
	struct ubi_sgl usgl;
};

/* Numbers of elements set in the @ubiblock_param array */
static int ubiblock_devs __initdata;

/* MTD devices specification parameters */
static struct ubiblock_param ubiblock_param[UBIBLOCK_MAX_DEVICES] __initdata;

struct ubiblock {
	struct ubi_volume_desc *desc;
	int ubi_num;
	int vol_id;
	int refcnt;
	int leb_size;

	struct gendisk *gd;
	struct request_queue *rq;

	struct workqueue_struct *wq;

	struct mutex dev_mutex;
	struct list_head list;
	struct blk_mq_tag_set tag_set;
};

/* Linked list of all ubiblock instances */
static LIST_HEAD(ubiblock_devices);
static DEFINE_IDR(ubiblock_minor_idr);
/* Protects ubiblock_devices and ubiblock_minor_idr */
static DEFINE_MUTEX(devices_mutex);
static int ubiblock_major;

static int __init ubiblock_set_param(const char *val,
				     const struct kernel_param *kp)
{
	int i, ret;
	size_t len;
	struct ubiblock_param *param;
	char buf[UBIBLOCK_PARAM_LEN];
	char *pbuf = &buf[0];
	char *tokens[UBIBLOCK_PARAM_COUNT];

	if (!val)
		return -EINVAL;

	len = strnlen(val, UBIBLOCK_PARAM_LEN);
	if (len == 0) {
		pr_warn("UBI: block: empty 'block=' parameter - ignored\n");
		return 0;
	}

	if (len == UBIBLOCK_PARAM_LEN) {
		pr_err("UBI: block: parameter \"%s\" is too long, max. is %d\n",
		       val, UBIBLOCK_PARAM_LEN);
		return -EINVAL;
	}

	strcpy(buf, val);

	/* Get rid of the final newline */
	if (buf[len - 1] == '\n')
		buf[len - 1] = '\0';

	for (i = 0; i < UBIBLOCK_PARAM_COUNT; i++)
		tokens[i] = strsep(&pbuf, ",");

	param = &ubiblock_param[ubiblock_devs];
	if (tokens[1]) {
		/* Two parameters: can be 'ubi, vol_id' or 'ubi, vol_name' */
		ret = kstrtoint(tokens[0], 10, &param->ubi_num);
		if (ret < 0)
			return -EINVAL;

		/* Second param can be a number or a name */
		ret = kstrtoint(tokens[1], 10, &param->vol_id);
		if (ret < 0) {
			param->vol_id = -1;
			strcpy(param->name, tokens[1]);
		}

	} else {
		/* One parameter: must be device path */
		strcpy(param->name, tokens[0]);
		param->ubi_num = -1;
		param->vol_id = -1;
	}

	ubiblock_devs++;

	return 0;
}

static const struct kernel_param_ops ubiblock_param_ops = {
	.set    = ubiblock_set_param,
};
module_param_cb(block, &ubiblock_param_ops, NULL, 0);
MODULE_PARM_DESC(block, "Attach block devices to UBI volumes. Parameter format: block=<path|dev,num|dev,name>.\n"
			"Multiple \"block\" parameters may be specified.\n"
			"UBI volumes may be specified by their number, name, or path to the device node.\n"
			"Examples\n"
			"Using the UBI volume path:\n"
			"ubi.block=/dev/ubi0_0\n"
			"Using the UBI device, and the volume name:\n"
			"ubi.block=0,rootfs\n"
			"Using both UBI device number and UBI volume number:\n"
			"ubi.block=0,0\n");

static struct ubiblock *find_dev_nolock(int ubi_num, int vol_id)
{
	struct ubiblock *dev;

	list_for_each_entry(dev, &ubiblock_devices, list)
		if (dev->ubi_num == ubi_num && dev->vol_id == vol_id)
			return dev;
	return NULL;
}

static int ubiblock_read(struct ubiblock_pdu *pdu)
{
	int ret, leb, offset, bytes_left, to_read;
	u64 pos;
	struct request *req = blk_mq_rq_from_pdu(pdu);
	struct ubiblock *dev = req->q->queuedata;

	to_read = blk_rq_bytes(req);
	pos = blk_rq_pos(req) << 9;

	/* Get LEB:offset address to read from */
	offset = do_div(pos, dev->leb_size);
	leb = pos;
	bytes_left = to_read;

	while (bytes_left) {
		/*
		 * We can only read one LEB at a time. Therefore if the read
		 * length is larger than one LEB size, we split the operation.
		 */
		if (offset + to_read > dev->leb_size)
			to_read = dev->leb_size - offset;

		ret = ubi_read_sg(dev->desc, leb, &pdu->usgl, offset, to_read);
		if (ret < 0)
			return ret;

		bytes_left -= to_read;
		to_read = bytes_left;
		leb += 1;
		offset = 0;
	}
	return 0;
}

static int ubiblock_open(struct block_device *bdev, fmode_t mode)
{
	struct ubiblock *dev = bdev->bd_disk->private_data;
	int ret;

	mutex_lock(&dev->dev_mutex);
	if (dev->refcnt > 0) {
		/*
		 * The volume is already open, just increase the reference
		 * counter.
		 */
		goto out_done;
	}

	/*
	 * We want users to be aware they should only mount us as read-only.
	 * It's just a paranoid check, as write requests will get rejected
	 * in any case.
	 */
	if (mode & FMODE_WRITE) {
		ret = -EPERM;
		goto out_unlock;
	}

	dev->desc = ubi_open_volume(dev->ubi_num, dev->vol_id, UBI_READONLY);
	if (IS_ERR(dev->desc)) {
		dev_err(disk_to_dev(dev->gd), "failed to open ubi volume %d_%d",
			dev->ubi_num, dev->vol_id);
		ret = PTR_ERR(dev->desc);
		dev->desc = NULL;
		goto out_unlock;
	}

out_done:
	dev->refcnt++;
	mutex_unlock(&dev->dev_mutex);
	return 0;

out_unlock:
	mutex_unlock(&dev->dev_mutex);
	return ret;
}

static void ubiblock_release(struct gendisk *gd, fmode_t mode)
{
	struct ubiblock *dev = gd->private_data;

	mutex_lock(&dev->dev_mutex);
	dev->refcnt--;
	if (dev->refcnt == 0) {
		ubi_close_volume(dev->desc);
		dev->desc = NULL;
	}
	mutex_unlock(&dev->dev_mutex);
}

static int ubiblock_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
	/* Some tools might require this information */
	geo->heads = 1;
	geo->cylinders = 1;
	geo->sectors = get_capacity(bdev->bd_disk);
	geo->start = 0;
	return 0;
}

static const struct block_device_operations ubiblock_ops = {
	.owner = THIS_MODULE,
	.open = ubiblock_open,
	.release = ubiblock_release,
	.getgeo	= ubiblock_getgeo,
};

static void ubiblock_do_work(struct work_struct *work)
{
	int ret;
	struct ubiblock_pdu *pdu = container_of(work, struct ubiblock_pdu, work);
	struct request *req = blk_mq_rq_from_pdu(pdu);

	blk_mq_start_request(req);

	/*
	 * It is safe to ignore the return value of blk_rq_map_sg() because
	 * the number of sg entries is limited to UBI_MAX_SG_COUNT
	 * and ubi_read_sg() will check that limit.
	 */
	blk_rq_map_sg(req->q, req, pdu->usgl.sg);

	ret = ubiblock_read(pdu);
	rq_flush_dcache_pages(req);

	blk_mq_end_request(req, ret);
}

static int ubiblock_queue_rq(struct blk_mq_hw_ctx *hctx,
			     const struct blk_mq_queue_data *bd)
{
	struct request *req = bd->rq;
	struct ubiblock *dev = hctx->queue->queuedata;
	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);

	if (req->cmd_type != REQ_TYPE_FS)
		return BLK_MQ_RQ_QUEUE_ERROR;

	if (rq_data_dir(req) != READ)
		return BLK_MQ_RQ_QUEUE_ERROR; /* Write not implemented */

	ubi_sgl_init(&pdu->usgl);
	queue_work(dev->wq, &pdu->work);

	return BLK_MQ_RQ_QUEUE_OK;
}

static int ubiblock_init_request(void *data, struct request *req,
				 unsigned int hctx_idx,
				 unsigned int request_idx,
				 unsigned int numa_node)
{
	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);

	sg_init_table(pdu->usgl.sg, UBI_MAX_SG_COUNT);
	INIT_WORK(&pdu->work, ubiblock_do_work);

	return 0;
}

static struct blk_mq_ops ubiblock_mq_ops = {
	.queue_rq       = ubiblock_queue_rq,
	.init_request	= ubiblock_init_request,
	.map_queue      = blk_mq_map_queue,
};

int ubiblock_create(struct ubi_volume_info *vi)
{
	struct ubiblock *dev;
	struct gendisk *gd;
	u64 disk_capacity = vi->used_bytes >> 9;
	int ret;

	if ((sector_t)disk_capacity != disk_capacity)
		return -EFBIG;
	/* Check that the volume isn't already handled */
	mutex_lock(&devices_mutex);
	if (find_dev_nolock(vi->ubi_num, vi->vol_id)) {
		ret = -EEXIST;
		goto out_unlock;
	}

	dev = kzalloc(sizeof(struct ubiblock), GFP_KERNEL);
	if (!dev) {
		ret = -ENOMEM;
		goto out_unlock;
	}

	mutex_init(&dev->dev_mutex);

	dev->ubi_num = vi->ubi_num;
	dev->vol_id = vi->vol_id;
	dev->leb_size = vi->usable_leb_size;

	/* Initialize the gendisk of this ubiblock device */
	gd = alloc_disk(1);
	if (!gd) {
		pr_err("UBI: block: alloc_disk failed");
		ret = -ENODEV;
		goto out_free_dev;
	}

	gd->fops = &ubiblock_ops;
	gd->major = ubiblock_major;
	gd->first_minor = idr_alloc(&ubiblock_minor_idr, dev, 0, 0, GFP_KERNEL);
	if (gd->first_minor < 0) {
		dev_err(disk_to_dev(gd),
			"block: dynamic minor allocation failed");
		ret = -ENODEV;
		goto out_put_disk;
	}
	gd->private_data = dev;
	sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
	set_capacity(gd, disk_capacity);
	dev->gd = gd;

	dev->tag_set.ops = &ubiblock_mq_ops;
	dev->tag_set.queue_depth = 64;
	dev->tag_set.numa_node = NUMA_NO_NODE;
	dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
	dev->tag_set.cmd_size = sizeof(struct ubiblock_pdu);
	dev->tag_set.driver_data = dev;
	dev->tag_set.nr_hw_queues = 1;

	ret = blk_mq_alloc_tag_set(&dev->tag_set);
	if (ret) {
		dev_err(disk_to_dev(dev->gd), "blk_mq_alloc_tag_set failed");
		goto out_remove_minor;
	}

	dev->rq = blk_mq_init_queue(&dev->tag_set);
	if (IS_ERR(dev->rq)) {
		dev_err(disk_to_dev(gd), "blk_mq_init_queue failed");
		ret = PTR_ERR(dev->rq);
		goto out_free_tags;
	}
	blk_queue_max_segments(dev->rq, UBI_MAX_SG_COUNT);

	dev->rq->queuedata = dev;
	dev->gd->queue = dev->rq;

	/*
	 * Create one workqueue per volume (per registered block device).
	 * Rembember workqueues are cheap, they're not threads.
	 */
	dev->wq = alloc_workqueue("%s", 0, 0, gd->disk_name);
	if (!dev->wq) {
		ret = -ENOMEM;
		goto out_free_queue;
	}

	list_add_tail(&dev->list, &ubiblock_devices);

	/* Must be the last step: anyone can call file ops from now on */
	add_disk(dev->gd);
	dev_info(disk_to_dev(dev->gd), "created from ubi%d:%d(%s)",
		 dev->ubi_num, dev->vol_id, vi->name);
	mutex_unlock(&devices_mutex);
	return 0;

out_free_queue:
	blk_cleanup_queue(dev->rq);
out_free_tags:
	blk_mq_free_tag_set(&dev->tag_set);
out_remove_minor:
	idr_remove(&ubiblock_minor_idr, gd->first_minor);
out_put_disk:
	put_disk(dev->gd);
out_free_dev:
	kfree(dev);
out_unlock:
	mutex_unlock(&devices_mutex);

	return ret;
}

static void ubiblock_cleanup(struct ubiblock *dev)
{
	/* Stop new requests to arrive */
	del_gendisk(dev->gd);
	/* Flush pending work */
	destroy_workqueue(dev->wq);
	/* Finally destroy the blk queue */
	blk_cleanup_queue(dev->rq);
	blk_mq_free_tag_set(&dev->tag_set);
	dev_info(disk_to_dev(dev->gd), "released");
	idr_remove(&ubiblock_minor_idr, dev->gd->first_minor);
	put_disk(dev->gd);
}

int ubiblock_remove(struct ubi_volume_info *vi)
{
	struct ubiblock *dev;
	int ret;

	mutex_lock(&devices_mutex);
	dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
	if (!dev) {
		ret = -ENODEV;
		goto out_unlock;
	}

	/* Found a device, let's lock it so we can check if it's busy */
	mutex_lock(&dev->dev_mutex);
	if (dev->refcnt > 0) {
		ret = -EBUSY;
		goto out_unlock_dev;
	}

	/* Remove from device list */
	list_del(&dev->list);
	ubiblock_cleanup(dev);
	mutex_unlock(&dev->dev_mutex);
	mutex_unlock(&devices_mutex);

	kfree(dev);
	return 0;

out_unlock_dev:
	mutex_unlock(&dev->dev_mutex);
out_unlock:
	mutex_unlock(&devices_mutex);
	return ret;
}

static int ubiblock_resize(struct ubi_volume_info *vi)
{
	struct ubiblock *dev;
	u64 disk_capacity = vi->used_bytes >> 9;

	/*
	 * Need to lock the device list until we stop using the device,
	 * otherwise the device struct might get released in
	 * 'ubiblock_remove()'.
	 */
	mutex_lock(&devices_mutex);
	dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
	if (!dev) {
		mutex_unlock(&devices_mutex);
		return -ENODEV;
	}
	if ((sector_t)disk_capacity != disk_capacity) {
		mutex_unlock(&devices_mutex);
		dev_warn(disk_to_dev(dev->gd), "the volume is too big (%d LEBs), cannot resize",
			 vi->size);
		return -EFBIG;
	}

	mutex_lock(&dev->dev_mutex);

	if (get_capacity(dev->gd) != disk_capacity) {
		set_capacity(dev->gd, disk_capacity);
		dev_info(disk_to_dev(dev->gd), "resized to %lld bytes",
			 vi->used_bytes);
	}
	mutex_unlock(&dev->dev_mutex);
	mutex_unlock(&devices_mutex);
	return 0;
}

static int ubiblock_notify(struct notifier_block *nb,
			 unsigned long notification_type, void *ns_ptr)
{
	struct ubi_notification *nt = ns_ptr;

	switch (notification_type) {
	case UBI_VOLUME_ADDED:
		/*
		 * We want to enforce explicit block device creation for
		 * volumes, so when a volume is added we do nothing.
		 */
		break;
	case UBI_VOLUME_REMOVED:
		ubiblock_remove(&nt->vi);
		break;
	case UBI_VOLUME_RESIZED:
		ubiblock_resize(&nt->vi);
		break;
	case UBI_VOLUME_UPDATED:
		/*
		 * If the volume is static, a content update might mean the
		 * size (i.e. used_bytes) was also changed.
		 */
		if (nt->vi.vol_type == UBI_STATIC_VOLUME)
			ubiblock_resize(&nt->vi);
		break;
	default:
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block ubiblock_notifier = {
	.notifier_call = ubiblock_notify,
};

static struct ubi_volume_desc * __init
open_volume_desc(const char *name, int ubi_num, int vol_id)
{
	if (ubi_num == -1)
		/* No ubi num, name must be a vol device path */
		return ubi_open_volume_path(name, UBI_READONLY);
	else if (vol_id == -1)
		/* No vol_id, must be vol_name */
		return ubi_open_volume_nm(ubi_num, name, UBI_READONLY);
	else
		return ubi_open_volume(ubi_num, vol_id, UBI_READONLY);
}

static void __init ubiblock_create_from_param(void)
{
	int i, ret = 0;
	struct ubiblock_param *p;
	struct ubi_volume_desc *desc;
	struct ubi_volume_info vi;

	/*
	 * If there is an error creating one of the ubiblocks, continue on to
	 * create the following ubiblocks. This helps in a circumstance where
	 * the kernel command-line specifies multiple block devices and some
	 * may be broken, but we still want the working ones to come up.
	 */
	for (i = 0; i < ubiblock_devs; i++) {
		p = &ubiblock_param[i];

		desc = open_volume_desc(p->name, p->ubi_num, p->vol_id);
		if (IS_ERR(desc)) {
			pr_err(
			       "UBI: block: can't open volume on ubi%d_%d, err=%ld",
			       p->ubi_num, p->vol_id, PTR_ERR(desc));
			continue;
		}

		ubi_get_volume_info(desc, &vi);
		ubi_close_volume(desc);

		ret = ubiblock_create(&vi);
		if (ret) {
			pr_err(
			       "UBI: block: can't add '%s' volume on ubi%d_%d, err=%d",
			       vi.name, p->ubi_num, p->vol_id, ret);
			continue;
		}
	}
}

static void ubiblock_remove_all(void)
{
	struct ubiblock *next;
	struct ubiblock *dev;

	mutex_lock(&devices_mutex);
	list_for_each_entry_safe(dev, next, &ubiblock_devices, list) {
		/* The module is being forcefully removed */
		WARN_ON(dev->desc);
		/* Remove from device list */
		list_del(&dev->list);
		ubiblock_cleanup(dev);
		kfree(dev);
	}
	mutex_unlock(&devices_mutex);
}

int __init ubiblock_init(void)
{
	int ret;

	ubiblock_major = register_blkdev(0, "ubiblock");
	if (ubiblock_major < 0)
		return ubiblock_major;

	/*
	 * Attach block devices from 'block=' module param.
	 * Even if one block device in the param list fails to come up,
	 * still allow the module to load and leave any others up.
	 */
	ubiblock_create_from_param();

	/*
	 * Block devices are only created upon user requests, so we ignore
	 * existing volumes.
	 */
	ret = ubi_register_volume_notifier(&ubiblock_notifier, 1);
	if (ret)
		goto err_unreg;
	return 0;

err_unreg:
	unregister_blkdev(ubiblock_major, "ubiblock");
	ubiblock_remove_all();
	return ret;
}

void __exit ubiblock_exit(void)
{
	ubi_unregister_volume_notifier(&ubiblock_notifier);
	ubiblock_remove_all();
	unregister_blkdev(ubiblock_major, "ubiblock");
}