summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/mtd_blkdevs.c
blob: f336a9b855765e5ea236fddf9564f5f084793597 (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
/*
 * Interface to Linux block layer for MTD 'translation layers'.
 *
 * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/mtd/blktrans.h>
#include <linux/mtd/mtd.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
#include <linux/spinlock.h>
#include <linux/hdreg.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>

#include "mtdcore.h"

static LIST_HEAD(blktrans_majors);
static DEFINE_MUTEX(blktrans_ref_mutex);

static void blktrans_dev_release(struct kref *kref)
{
	struct mtd_blktrans_dev *dev =
		container_of(kref, struct mtd_blktrans_dev, ref);

	dev->disk->private_data = NULL;
	blk_cleanup_queue(dev->rq);
	put_disk(dev->disk);
	list_del(&dev->list);
	kfree(dev);
}

static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
{
	struct mtd_blktrans_dev *dev;

	mutex_lock(&blktrans_ref_mutex);
	dev = disk->private_data;

	if (!dev)
		goto unlock;
	kref_get(&dev->ref);
unlock:
	mutex_unlock(&blktrans_ref_mutex);
	return dev;
}

static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
{
	mutex_lock(&blktrans_ref_mutex);
	kref_put(&dev->ref, blktrans_dev_release);
	mutex_unlock(&blktrans_ref_mutex);
}


static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr,
			       struct mtd_blktrans_dev *dev,
			       struct request *req)
{
	unsigned long block, nsect;
	char *buf;

	block = blk_rq_pos(req) << 9 >> tr->blkshift;
	nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
	buf = bio_data(req->bio);

	if (req_op(req) == REQ_OP_FLUSH) {
		if (tr->flush(dev))
			return BLK_STS_IOERR;
		return BLK_STS_OK;
	}

	if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
	    get_capacity(req->rq_disk))
		return BLK_STS_IOERR;

	switch (req_op(req)) {
	case REQ_OP_DISCARD:
		if (tr->discard(dev, block, nsect))
			return BLK_STS_IOERR;
		return BLK_STS_OK;
	case REQ_OP_READ:
		for (; nsect > 0; nsect--, block++, buf += tr->blksize)
			if (tr->readsect(dev, block, buf))
				return BLK_STS_IOERR;
		rq_flush_dcache_pages(req);
		return BLK_STS_OK;
	case REQ_OP_WRITE:
		if (!tr->writesect)
			return BLK_STS_IOERR;

		rq_flush_dcache_pages(req);
		for (; nsect > 0; nsect--, block++, buf += tr->blksize)
			if (tr->writesect(dev, block, buf))
				return BLK_STS_IOERR;
	default:
		return BLK_STS_IOERR;
	}
}

int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
{
	return dev->bg_stop;
}
EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);

static void mtd_blktrans_work(struct work_struct *work)
{
	struct mtd_blktrans_dev *dev =
		container_of(work, struct mtd_blktrans_dev, work);
	struct mtd_blktrans_ops *tr = dev->tr;
	struct request_queue *rq = dev->rq;
	struct request *req = NULL;
	int background_done = 0;

	spin_lock_irq(rq->queue_lock);

	while (1) {
		blk_status_t res;

		dev->bg_stop = false;
		if (!req && !(req = blk_fetch_request(rq))) {
			if (tr->background && !background_done) {
				spin_unlock_irq(rq->queue_lock);
				mutex_lock(&dev->lock);
				tr->background(dev);
				mutex_unlock(&dev->lock);
				spin_lock_irq(rq->queue_lock);
				/*
				 * Do background processing just once per idle
				 * period.
				 */
				background_done = !dev->bg_stop;
				continue;
			}
			break;
		}

		spin_unlock_irq(rq->queue_lock);

		mutex_lock(&dev->lock);
		res = do_blktrans_request(dev->tr, dev, req);
		mutex_unlock(&dev->lock);

		spin_lock_irq(rq->queue_lock);

		if (!__blk_end_request_cur(req, res))
			req = NULL;

		background_done = 0;
	}

	spin_unlock_irq(rq->queue_lock);
}

static void mtd_blktrans_request(struct request_queue *rq)
{
	struct mtd_blktrans_dev *dev;
	struct request *req = NULL;

	dev = rq->queuedata;

	if (!dev)
		while ((req = blk_fetch_request(rq)) != NULL)
			__blk_end_request_all(req, BLK_STS_IOERR);
	else
		queue_work(dev->wq, &dev->work);
}

static int blktrans_open(struct block_device *bdev, fmode_t mode)
{
	struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
	int ret = 0;

	if (!dev)
		return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/

	mutex_lock(&mtd_table_mutex);
	mutex_lock(&dev->lock);

	if (dev->open)
		goto unlock;

	kref_get(&dev->ref);
	__module_get(dev->tr->owner);

	if (!dev->mtd)
		goto unlock;

	if (dev->tr->open) {
		ret = dev->tr->open(dev);
		if (ret)
			goto error_put;
	}

	ret = __get_mtd_device(dev->mtd);
	if (ret)
		goto error_release;
	dev->file_mode = mode;

unlock:
	dev->open++;
	mutex_unlock(&dev->lock);
	mutex_unlock(&mtd_table_mutex);
	blktrans_dev_put(dev);
	return ret;

error_release:
	if (dev->tr->release)
		dev->tr->release(dev);
error_put:
	module_put(dev->tr->owner);
	kref_put(&dev->ref, blktrans_dev_release);
	mutex_unlock(&dev->lock);
	mutex_unlock(&mtd_table_mutex);
	blktrans_dev_put(dev);
	return ret;
}

static void blktrans_release(struct gendisk *disk, fmode_t mode)
{
	struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);

	if (!dev)
		return;

	mutex_lock(&mtd_table_mutex);
	mutex_lock(&dev->lock);

	if (--dev->open)
		goto unlock;

	kref_put(&dev->ref, blktrans_dev_release);
	module_put(dev->tr->owner);

	if (dev->mtd) {
		if (dev->tr->release)
			dev->tr->release(dev);
		__put_mtd_device(dev->mtd);
	}
unlock:
	mutex_unlock(&dev->lock);
	mutex_unlock(&mtd_table_mutex);
	blktrans_dev_put(dev);
}

static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
	struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
	int ret = -ENXIO;

	if (!dev)
		return ret;

	mutex_lock(&dev->lock);

	if (!dev->mtd)
		goto unlock;

	ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
unlock:
	mutex_unlock(&dev->lock);
	blktrans_dev_put(dev);
	return ret;
}

static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
			      unsigned int cmd, unsigned long arg)
{
	struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
	int ret = -ENXIO;

	if (!dev)
		return ret;

	mutex_lock(&dev->lock);

	if (!dev->mtd)
		goto unlock;

	switch (cmd) {
	case BLKFLSBUF:
		ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
		break;
	default:
		ret = -ENOTTY;
	}
unlock:
	mutex_unlock(&dev->lock);
	blktrans_dev_put(dev);
	return ret;
}

static const struct block_device_operations mtd_block_ops = {
	.owner		= THIS_MODULE,
	.open		= blktrans_open,
	.release	= blktrans_release,
	.ioctl		= blktrans_ioctl,
	.getgeo		= blktrans_getgeo,
};

int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
{
	struct mtd_blktrans_ops *tr = new->tr;
	struct mtd_blktrans_dev *d;
	int last_devnum = -1;
	struct gendisk *gd;
	int ret;

	if (mutex_trylock(&mtd_table_mutex)) {
		mutex_unlock(&mtd_table_mutex);
		BUG();
	}

	mutex_lock(&blktrans_ref_mutex);
	list_for_each_entry(d, &tr->devs, list) {
		if (new->devnum == -1) {
			/* Use first free number */
			if (d->devnum != last_devnum+1) {
				/* Found a free devnum. Plug it in here */
				new->devnum = last_devnum+1;
				list_add_tail(&new->list, &d->list);
				goto added;
			}
		} else if (d->devnum == new->devnum) {
			/* Required number taken */
			mutex_unlock(&blktrans_ref_mutex);
			return -EBUSY;
		} else if (d->devnum > new->devnum) {
			/* Required number was free */
			list_add_tail(&new->list, &d->list);
			goto added;
		}
		last_devnum = d->devnum;
	}

	ret = -EBUSY;
	if (new->devnum == -1)
		new->devnum = last_devnum+1;

	/* Check that the device and any partitions will get valid
	 * minor numbers and that the disk naming code below can cope
	 * with this number. */
	if (new->devnum > (MINORMASK >> tr->part_bits) ||
	    (tr->part_bits && new->devnum >= 27 * 26)) {
		mutex_unlock(&blktrans_ref_mutex);
		goto error1;
	}

	list_add_tail(&new->list, &tr->devs);
 added:
	mutex_unlock(&blktrans_ref_mutex);

	mutex_init(&new->lock);
	kref_init(&new->ref);
	if (!tr->writesect)
		new->readonly = 1;

	/* Create gendisk */
	ret = -ENOMEM;
	gd = alloc_disk(1 << tr->part_bits);

	if (!gd)
		goto error2;

	new->disk = gd;
	gd->private_data = new;
	gd->major = tr->major;
	gd->first_minor = (new->devnum) << tr->part_bits;
	gd->fops = &mtd_block_ops;

	if (tr->part_bits)
		if (new->devnum < 26)
			snprintf(gd->disk_name, sizeof(gd->disk_name),
				 "%s%c", tr->name, 'a' + new->devnum);
		else
			snprintf(gd->disk_name, sizeof(gd->disk_name),
				 "%s%c%c", tr->name,
				 'a' - 1 + new->devnum / 26,
				 'a' + new->devnum % 26);
	else
		snprintf(gd->disk_name, sizeof(gd->disk_name),
			 "%s%d", tr->name, new->devnum);

	set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);

	/* Create the request queue */
	spin_lock_init(&new->queue_lock);
	new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);

	if (!new->rq)
		goto error3;

	if (tr->flush)
		blk_queue_write_cache(new->rq, true, false);

	new->rq->queuedata = new;
	blk_queue_logical_block_size(new->rq, tr->blksize);

	blk_queue_bounce_limit(new->rq, BLK_BOUNCE_HIGH);
	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, new->rq);

	if (tr->discard) {
		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
		blk_queue_max_discard_sectors(new->rq, UINT_MAX);
	}

	gd->queue = new->rq;

	/* Create processing workqueue */
	new->wq = alloc_workqueue("%s%d", 0, 0,
				  tr->name, new->mtd->index);
	if (!new->wq)
		goto error4;
	INIT_WORK(&new->work, mtd_blktrans_work);

	if (new->readonly)
		set_disk_ro(gd, 1);

	device_add_disk(&new->mtd->dev, gd);

	if (new->disk_attributes) {
		ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
					new->disk_attributes);
		WARN_ON(ret);
	}
	return 0;
error4:
	blk_cleanup_queue(new->rq);
error3:
	put_disk(new->disk);
error2:
	list_del(&new->list);
error1:
	return ret;
}

int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
{
	unsigned long flags;

	if (mutex_trylock(&mtd_table_mutex)) {
		mutex_unlock(&mtd_table_mutex);
		BUG();
	}

	if (old->disk_attributes)
		sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
						old->disk_attributes);

	/* Stop new requests to arrive */
	del_gendisk(old->disk);

	/* Stop workqueue. This will perform any pending request. */
	destroy_workqueue(old->wq);

	/* Kill current requests */
	spin_lock_irqsave(&old->queue_lock, flags);
	old->rq->queuedata = NULL;
	blk_start_queue(old->rq);
	spin_unlock_irqrestore(&old->queue_lock, flags);

	/* If the device is currently open, tell trans driver to close it,
		then put mtd device, and don't touch it again */
	mutex_lock(&old->lock);
	if (old->open) {
		if (old->tr->release)
			old->tr->release(old);
		__put_mtd_device(old->mtd);
	}

	old->mtd = NULL;

	mutex_unlock(&old->lock);
	blktrans_dev_put(old);
	return 0;
}

static void blktrans_notify_remove(struct mtd_info *mtd)
{
	struct mtd_blktrans_ops *tr;
	struct mtd_blktrans_dev *dev, *next;

	list_for_each_entry(tr, &blktrans_majors, list)
		list_for_each_entry_safe(dev, next, &tr->devs, list)
			if (dev->mtd == mtd)
				tr->remove_dev(dev);
}

static void blktrans_notify_add(struct mtd_info *mtd)
{
	struct mtd_blktrans_ops *tr;

	if (mtd->type == MTD_ABSENT)
		return;

	list_for_each_entry(tr, &blktrans_majors, list)
		tr->add_mtd(tr, mtd);
}

static struct mtd_notifier blktrans_notifier = {
	.add = blktrans_notify_add,
	.remove = blktrans_notify_remove,
};

int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
{
	struct mtd_info *mtd;
	int ret;

	/* Register the notifier if/when the first device type is
	   registered, to prevent the link/init ordering from fucking
	   us over. */
	if (!blktrans_notifier.list.next)
		register_mtd_user(&blktrans_notifier);


	mutex_lock(&mtd_table_mutex);

	ret = register_blkdev(tr->major, tr->name);
	if (ret < 0) {
		printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
		       tr->name, tr->major, ret);
		mutex_unlock(&mtd_table_mutex);
		return ret;
	}

	if (ret)
		tr->major = ret;

	tr->blkshift = ffs(tr->blksize) - 1;

	INIT_LIST_HEAD(&tr->devs);
	list_add(&tr->list, &blktrans_majors);

	mtd_for_each_device(mtd)
		if (mtd->type != MTD_ABSENT)
			tr->add_mtd(tr, mtd);

	mutex_unlock(&mtd_table_mutex);
	return 0;
}

int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
{
	struct mtd_blktrans_dev *dev, *next;

	mutex_lock(&mtd_table_mutex);

	/* Remove it from the list of active majors */
	list_del(&tr->list);

	list_for_each_entry_safe(dev, next, &tr->devs, list)
		tr->remove_dev(dev);

	unregister_blkdev(tr->major, tr->name);
	mutex_unlock(&mtd_table_mutex);

	BUG_ON(!list_empty(&tr->devs));
	return 0;
}

static void __exit mtd_blktrans_exit(void)
{
	/* No race here -- if someone's currently in register_mtd_blktrans
	   we're screwed anyway. */
	if (blktrans_notifier.list.next)
		unregister_mtd_user(&blktrans_notifier);
}

module_exit(mtd_blktrans_exit);

EXPORT_SYMBOL_GPL(register_mtd_blktrans);
EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);

MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");