summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/devices/block2mtd.c
blob: 0aaa0ced9aba0acd7d5105d16a4fe90b4323be73 (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
/*
 * $Id: block2mtd.c,v 1.29 2005/11/07 11:14:24 gleixner Exp $
 *
 * block2mtd.c - create an mtd from a block device
 *
 * Copyright (C) 2001,2002	Simon Evans <spse@secret.org.uk>
 * Copyright (C) 2004,2005	Jörn Engel <joern@wh.fh-wedel.de>
 *
 * Licence: GPL
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/pagemap.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/mtd/mtd.h>
#include <linux/buffer_head.h>

#define VERSION "$Revision: 1.29 $"


#define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
#define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)


/* Info for the block device */
struct block2mtd_dev {
	struct list_head list;
	struct block_device *blkdev;
	struct mtd_info mtd;
	struct semaphore write_mutex;
};


/* Static info about the MTD, used in cleanup_module */
static LIST_HEAD(blkmtd_device_list);


#define PAGE_READAHEAD 64
void cache_readahead(struct address_space *mapping, int index)
{
	filler_t *filler = (filler_t*)mapping->a_ops->readpage;
	int i, pagei;
	unsigned ret = 0;
	unsigned long end_index;
	struct page *page;
	LIST_HEAD(page_pool);
	struct inode *inode = mapping->host;
	loff_t isize = i_size_read(inode);

	if (!isize) {
		INFO("iSize=0 in cache_readahead\n");
		return;
	}

	end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);

	read_lock_irq(&mapping->tree_lock);
	for (i = 0; i < PAGE_READAHEAD; i++) {
		pagei = index + i;
		if (pagei > end_index) {
			INFO("Overrun end of disk in cache readahead\n");
			break;
		}
		page = radix_tree_lookup(&mapping->page_tree, pagei);
		if (page && (!i))
			break;
		if (page)
			continue;
		read_unlock_irq(&mapping->tree_lock);
		page = page_cache_alloc_cold(mapping);
		read_lock_irq(&mapping->tree_lock);
		if (!page)
			break;
		page->index = pagei;
		list_add(&page->lru, &page_pool);
		ret++;
	}
	read_unlock_irq(&mapping->tree_lock);
	if (ret)
		read_cache_pages(mapping, &page_pool, filler, NULL);
}


static struct page* page_readahead(struct address_space *mapping, int index)
{
	filler_t *filler = (filler_t*)mapping->a_ops->readpage;
	cache_readahead(mapping, index);
	return read_cache_page(mapping, index, filler, NULL);
}


/* erase a specified part of the device */
static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
{
	struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
	struct page *page;
	int index = to >> PAGE_SHIFT;	// page index
	int pages = len >> PAGE_SHIFT;
	u_long *p;
	u_long *max;

	while (pages) {
		page = page_readahead(mapping, index);
		if (!page)
			return -ENOMEM;
		if (IS_ERR(page))
			return PTR_ERR(page);

		max = (u_long*)page_address(page) + PAGE_SIZE;
		for (p=(u_long*)page_address(page); p<max; p++)
			if (*p != -1UL) {
				lock_page(page);
				memset(page_address(page), 0xff, PAGE_SIZE);
				set_page_dirty(page);
				unlock_page(page);
				break;
			}

		page_cache_release(page);
		pages--;
		index++;
	}
	return 0;
}
static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	struct block2mtd_dev *dev = mtd->priv;
	size_t from = instr->addr;
	size_t len = instr->len;
	int err;

	instr->state = MTD_ERASING;
	down(&dev->write_mutex);
	err = _block2mtd_erase(dev, from, len);
	up(&dev->write_mutex);
	if (err) {
		ERROR("erase failed err = %d", err);
		instr->state = MTD_ERASE_FAILED;
	} else
		instr->state = MTD_ERASE_DONE;

	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);
	return err;
}


static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
		size_t *retlen, u_char *buf)
{
	struct block2mtd_dev *dev = mtd->priv;
	struct page *page;
	int index = from >> PAGE_SHIFT;
	int offset = from & (PAGE_SIZE-1);
	int cpylen;

	if (from > mtd->size)
		return -EINVAL;
	if (from + len > mtd->size)
		len = mtd->size - from;

	if (retlen)
		*retlen = 0;

	while (len) {
		if ((offset + len) > PAGE_SIZE)
			cpylen = PAGE_SIZE - offset;	// multiple pages
		else
			cpylen = len;	// this page
		len = len - cpylen;

		//      Get page
		page = page_readahead(dev->blkdev->bd_inode->i_mapping, index);
		if (!page)
			return -ENOMEM;
		if (IS_ERR(page))
			return PTR_ERR(page);

		memcpy(buf, page_address(page) + offset, cpylen);
		page_cache_release(page);

		if (retlen)
			*retlen += cpylen;
		buf += cpylen;
		offset = 0;
		index++;
	}
	return 0;
}


/* write data to the underlying device */
static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
		loff_t to, size_t len, size_t *retlen)
{
	struct page *page;
	struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
	int index = to >> PAGE_SHIFT;	// page index
	int offset = to & ~PAGE_MASK;	// page offset
	int cpylen;

	if (retlen)
		*retlen = 0;
	while (len) {
		if ((offset+len) > PAGE_SIZE)
			cpylen = PAGE_SIZE - offset;	// multiple pages
		else
			cpylen = len;			// this page
		len = len - cpylen;

		//	Get page
		page = page_readahead(mapping, index);
		if (!page)
			return -ENOMEM;
		if (IS_ERR(page))
			return PTR_ERR(page);

		if (memcmp(page_address(page)+offset, buf, cpylen)) {
			lock_page(page);
			memcpy(page_address(page) + offset, buf, cpylen);
			set_page_dirty(page);
			unlock_page(page);
		}
		page_cache_release(page);

		if (retlen)
			*retlen += cpylen;

		buf += cpylen;
		offset = 0;
		index++;
	}
	return 0;
}
static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
		size_t *retlen, const u_char *buf)
{
	struct block2mtd_dev *dev = mtd->priv;
	int err;

	if (!len)
		return 0;
	if (to >= mtd->size)
		return -ENOSPC;
	if (to + len > mtd->size)
		len = mtd->size - to;

	down(&dev->write_mutex);
	err = _block2mtd_write(dev, buf, to, len, retlen);
	up(&dev->write_mutex);
	if (err > 0)
		err = 0;
	return err;
}


/* sync the device - wait until the write queue is empty */
static void block2mtd_sync(struct mtd_info *mtd)
{
	struct block2mtd_dev *dev = mtd->priv;
	sync_blockdev(dev->blkdev);
	return;
}


static void block2mtd_free_device(struct block2mtd_dev *dev)
{
	if (!dev)
		return;

	kfree(dev->mtd.name);

	if (dev->blkdev) {
		invalidate_inode_pages(dev->blkdev->bd_inode->i_mapping);
		close_bdev_excl(dev->blkdev);
	}

	kfree(dev);
}


/* FIXME: ensure that mtd->size % erase_size == 0 */
static struct block2mtd_dev *add_device(char *devname, int erase_size)
{
	struct block_device *bdev;
	struct block2mtd_dev *dev;

	if (!devname)
		return NULL;

	dev = kmalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
	if (!dev)
		return NULL;
	memset(dev, 0, sizeof(*dev));

	/* Get a handle on the device */
	bdev = open_bdev_excl(devname, O_RDWR, NULL);
	if (IS_ERR(bdev)) {
		ERROR("error: cannot open device %s", devname);
		goto devinit_err;
	}
	dev->blkdev = bdev;

	if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
		ERROR("attempting to use an MTD device as a block device");
		goto devinit_err;
	}

	init_MUTEX(&dev->write_mutex);

	/* Setup the MTD structure */
	/* make the name contain the block device in */
	dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
			GFP_KERNEL);
	if (!dev->mtd.name)
		goto devinit_err;

	sprintf(dev->mtd.name, "block2mtd: %s", devname);

	dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
	dev->mtd.erasesize = erase_size;
	dev->mtd.type = MTD_RAM;
	dev->mtd.flags = MTD_CAP_RAM;
	dev->mtd.erase = block2mtd_erase;
	dev->mtd.write = block2mtd_write;
	dev->mtd.writev = default_mtd_writev;
	dev->mtd.sync = block2mtd_sync;
	dev->mtd.read = block2mtd_read;
	dev->mtd.readv = default_mtd_readv;
	dev->mtd.priv = dev;
	dev->mtd.owner = THIS_MODULE;

	if (add_mtd_device(&dev->mtd)) {
		/* Device didnt get added, so free the entry */
		goto devinit_err;
	}
	list_add(&dev->list, &blkmtd_device_list);
	INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
			dev->mtd.name + strlen("blkmtd: "),
			dev->mtd.erasesize >> 10, dev->mtd.erasesize);
	return dev;

devinit_err:
	block2mtd_free_device(dev);
	return NULL;
}


static int ustrtoul(const char *cp, char **endp, unsigned int base)
{
	unsigned long result = simple_strtoul(cp, endp, base);
	switch (**endp) {
	case 'G' :
		result *= 1024;
	case 'M':
		result *= 1024;
	case 'k':
		result *= 1024;
	/* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
		if ((*endp)[1] == 'i')
			(*endp) += 2;
	}
	return result;
}


static int parse_num(size_t *num, const char *token)
{
	char *endp;
	size_t n;

	n = (size_t) ustrtoul(token, &endp, 0);
	if (*endp)
		return -EINVAL;

	*num = n;
	return 0;
}


static int parse_name(char **pname, const char *token, size_t limit)
{
	size_t len;
	char *name;

	len = strlen(token) + 1;
	if (len > limit)
		return -ENOSPC;

	name = kmalloc(len, GFP_KERNEL);
	if (!name)
		return -ENOMEM;

	strcpy(name, token);

	*pname = name;
	return 0;
}


static inline void kill_final_newline(char *str)
{
	char *newline = strrchr(str, '\n');
	if (newline && !newline[1])
		*newline = 0;
}


#define parse_err(fmt, args...) do {		\
	ERROR("block2mtd: " fmt "\n", ## args);	\
	return 0;				\
} while (0)

static int block2mtd_setup(const char *val, struct kernel_param *kp)
{
	char buf[80+12], *str=buf; /* 80 for device, 12 for erase size */
	char *token[2];
	char *name;
	size_t erase_size = PAGE_SIZE;
	int i, ret;

	if (strnlen(val, sizeof(buf)) >= sizeof(buf))
		parse_err("parameter too long");

	strcpy(str, val);
	kill_final_newline(str);

	for (i=0; i<2; i++)
		token[i] = strsep(&str, ",");

	if (str)
		parse_err("too many arguments");

	if (!token[0])
		parse_err("no argument");

	ret = parse_name(&name, token[0], 80);
	if (ret == -ENOMEM)
		parse_err("out of memory");
	if (ret == -ENOSPC)
		parse_err("name too long");
	if (ret)
		return 0;

	if (token[1]) {
		ret = parse_num(&erase_size, token[1]);
		if (ret)
			parse_err("illegal erase size");
	}

	add_device(name, erase_size);

	return 0;
}


module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");

static int __init block2mtd_init(void)
{
	INFO("version " VERSION);
	return 0;
}


static void __devexit block2mtd_exit(void)
{
	struct list_head *pos, *next;

	/* Remove the MTD devices */
	list_for_each_safe(pos, next, &blkmtd_device_list) {
		struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
		block2mtd_sync(&dev->mtd);
		del_mtd_device(&dev->mtd);
		INFO("mtd%d: [%s] removed", dev->mtd.index,
				dev->mtd.name + strlen("blkmtd: "));
		list_del(&dev->list);
		block2mtd_free_device(dev);
	}
}


module_init(block2mtd_init);
module_exit(block2mtd_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
MODULE_DESCRIPTION("Emulate an MTD using a block device");
OpenPOWER on IntegriCloud