block2mtd.c revision eadcf0d704a46979c29984fa05f1fc413c775bcb 
1/*
2 * $Id: block2mtd.c,v 1.30 2005/11/29 14:48:32 gleixner Exp $
3 *
4 * block2mtd.c - create an mtd from a block device
5 *
6 * Copyright (C) 2001,2002	Simon Evans <spse@secret.org.uk>
7 * Copyright (C) 2004-2006	Joern Engel <joern@wh.fh-wedel.de>
8 *
9 * Licence: GPL
10 */
11#include <linux/module.h>
12#include <linux/fs.h>
13#include <linux/blkdev.h>
14#include <linux/bio.h>
15#include <linux/pagemap.h>
16#include <linux/list.h>
17#include <linux/init.h>
18#include <linux/mtd/mtd.h>
19#include <linux/buffer_head.h>
20#include <linux/mutex.h>
21#include <linux/mount.h>
22
23#define VERSION "$Revision: 1.30 $"
24
25
26#define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
27#define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
28
29
30/* Info for the block device */
31struct block2mtd_dev {
32	struct list_head list;
33	struct block_device *blkdev;
34	struct mtd_info mtd;
35	struct mutex write_mutex;
36};
37
38
39/* Static info about the MTD, used in cleanup_module */
40static LIST_HEAD(blkmtd_device_list);
41
42
43static struct page *page_read(struct address_space *mapping, int index)
44{
45	return read_mapping_page(mapping, index, NULL);
46}
47
48/* erase a specified part of the device */
49static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
50{
51	struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
52	struct page *page;
53	int index = to >> PAGE_SHIFT;	// page index
54	int pages = len >> PAGE_SHIFT;
55	u_long *p;
56	u_long *max;
57
58	while (pages) {
59		page = page_read(mapping, index);
60		if (!page)
61			return -ENOMEM;
62		if (IS_ERR(page))
63			return PTR_ERR(page);
64
65		max = page_address(page) + PAGE_SIZE;
66		for (p=page_address(page); p<max; p++)
67			if (*p != -1UL) {
68				lock_page(page);
69				memset(page_address(page), 0xff, PAGE_SIZE);
70				set_page_dirty(page);
71				unlock_page(page);
72				break;
73			}
74
75		page_cache_release(page);
76		pages--;
77		index++;
78	}
79	return 0;
80}
81static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
82{
83	struct block2mtd_dev *dev = mtd->priv;
84	size_t from = instr->addr;
85	size_t len = instr->len;
86	int err;
87
88	instr->state = MTD_ERASING;
89	mutex_lock(&dev->write_mutex);
90	err = _block2mtd_erase(dev, from, len);
91	mutex_unlock(&dev->write_mutex);
92	if (err) {
93		ERROR("erase failed err = %d", err);
94		instr->state = MTD_ERASE_FAILED;
95	} else
96		instr->state = MTD_ERASE_DONE;
97
98	instr->state = MTD_ERASE_DONE;
99	mtd_erase_callback(instr);
100	return err;
101}
102
103
104static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
105		size_t *retlen, u_char *buf)
106{
107	struct block2mtd_dev *dev = mtd->priv;
108	struct page *page;
109	int index = from >> PAGE_SHIFT;
110	int offset = from & (PAGE_SIZE-1);
111	int cpylen;
112
113	if (from > mtd->size)
114		return -EINVAL;
115	if (from + len > mtd->size)
116		len = mtd->size - from;
117
118	if (retlen)
119		*retlen = 0;
120
121	while (len) {
122		if ((offset + len) > PAGE_SIZE)
123			cpylen = PAGE_SIZE - offset;	// multiple pages
124		else
125			cpylen = len;	// this page
126		len = len - cpylen;
127
128		page = page_read(dev->blkdev->bd_inode->i_mapping, index);
129		if (!page)
130			return -ENOMEM;
131		if (IS_ERR(page))
132			return PTR_ERR(page);
133
134		memcpy(buf, page_address(page) + offset, cpylen);
135		page_cache_release(page);
136
137		if (retlen)
138			*retlen += cpylen;
139		buf += cpylen;
140		offset = 0;
141		index++;
142	}
143	return 0;
144}
145
146
147/* write data to the underlying device */
148static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
149		loff_t to, size_t len, size_t *retlen)
150{
151	struct page *page;
152	struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
153	int index = to >> PAGE_SHIFT;	// page index
154	int offset = to & ~PAGE_MASK;	// page offset
155	int cpylen;
156
157	if (retlen)
158		*retlen = 0;
159	while (len) {
160		if ((offset+len) > PAGE_SIZE)
161			cpylen = PAGE_SIZE - offset;	// multiple pages
162		else
163			cpylen = len;			// this page
164		len = len - cpylen;
165
166		page = page_read(mapping, index);
167		if (!page)
168			return -ENOMEM;
169		if (IS_ERR(page))
170			return PTR_ERR(page);
171
172		if (memcmp(page_address(page)+offset, buf, cpylen)) {
173			lock_page(page);
174			memcpy(page_address(page) + offset, buf, cpylen);
175			set_page_dirty(page);
176			unlock_page(page);
177		}
178		page_cache_release(page);
179
180		if (retlen)
181			*retlen += cpylen;
182
183		buf += cpylen;
184		offset = 0;
185		index++;
186	}
187	return 0;
188}
189
190
191static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
192		size_t *retlen, const u_char *buf)
193{
194	struct block2mtd_dev *dev = mtd->priv;
195	int err;
196
197	if (!len)
198		return 0;
199	if (to >= mtd->size)
200		return -ENOSPC;
201	if (to + len > mtd->size)
202		len = mtd->size - to;
203
204	mutex_lock(&dev->write_mutex);
205	err = _block2mtd_write(dev, buf, to, len, retlen);
206	mutex_unlock(&dev->write_mutex);
207	if (err > 0)
208		err = 0;
209	return err;
210}
211
212
213/* sync the device - wait until the write queue is empty */
214static void block2mtd_sync(struct mtd_info *mtd)
215{
216	struct block2mtd_dev *dev = mtd->priv;
217	sync_blockdev(dev->blkdev);
218	return;
219}
220
221
222static void block2mtd_free_device(struct block2mtd_dev *dev)
223{
224	if (!dev)
225		return;
226
227	kfree(dev->mtd.name);
228
229	if (dev->blkdev) {
230		invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
231					0, -1);
232		close_bdev_excl(dev->blkdev);
233	}
234
235	kfree(dev);
236}
237
238
239/* FIXME: ensure that mtd->size % erase_size == 0 */
240static struct block2mtd_dev *add_device(char *devname, int erase_size)
241{
242	struct block_device *bdev;
243	struct block2mtd_dev *dev;
244	char *name;
245
246	if (!devname)
247		return NULL;
248
249	dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
250	if (!dev)
251		return NULL;
252
253	/* Get a handle on the device */
254	bdev = open_bdev_excl(devname, O_RDWR, NULL);
255#ifndef MODULE
256	if (IS_ERR(bdev)) {
257
258		/* We might not have rootfs mounted at this point. Try
259		   to resolve the device name by other means. */
260
261		dev_t devt = name_to_dev_t(devname);
262		if (devt) {
263			bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);
264		}
265	}
266#endif
267
268	if (IS_ERR(bdev)) {
269		ERROR("error: cannot open device %s", devname);
270		goto devinit_err;
271	}
272	dev->blkdev = bdev;
273
274	if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
275		ERROR("attempting to use an MTD device as a block device");
276		goto devinit_err;
277	}
278
279	mutex_init(&dev->write_mutex);
280
281	/* Setup the MTD structure */
282	/* make the name contain the block device in */
283	name = kmalloc(sizeof("block2mtd: ") + strlen(devname) + 1,
284			GFP_KERNEL);
285	if (!name)
286		goto devinit_err;
287
288	sprintf(name, "block2mtd: %s", devname);
289	dev->mtd.name = name;
290
291	dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
292	dev->mtd.erasesize = erase_size;
293	dev->mtd.writesize = 1;
294	dev->mtd.type = MTD_RAM;
295	dev->mtd.flags = MTD_CAP_RAM;
296	dev->mtd.erase = block2mtd_erase;
297	dev->mtd.write = block2mtd_write;
298	dev->mtd.writev = default_mtd_writev;
299	dev->mtd.sync = block2mtd_sync;
300	dev->mtd.read = block2mtd_read;
301	dev->mtd.priv = dev;
302	dev->mtd.owner = THIS_MODULE;
303
304	if (add_mtd_device(&dev->mtd)) {
305		/* Device didnt get added, so free the entry */
306		goto devinit_err;
307	}
308	list_add(&dev->list, &blkmtd_device_list);
309	INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
310			dev->mtd.name + strlen("block2mtd: "),
311			dev->mtd.erasesize >> 10, dev->mtd.erasesize);
312	return dev;
313
314devinit_err:
315	block2mtd_free_device(dev);
316	return NULL;
317}
318
319
320/* This function works similar to reguler strtoul.  In addition, it
321 * allows some suffixes for a more human-readable number format:
322 * ki, Ki, kiB, KiB	- multiply result with 1024
323 * Mi, MiB		- multiply result with 1024^2
324 * Gi, GiB		- multiply result with 1024^3
325 */
326static int ustrtoul(const char *cp, char **endp, unsigned int base)
327{
328	unsigned long result = simple_strtoul(cp, endp, base);
329	switch (**endp) {
330	case 'G' :
331		result *= 1024;
332	case 'M':
333		result *= 1024;
334	case 'K':
335	case 'k':
336		result *= 1024;
337	/* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
338		if ((*endp)[1] == 'i') {
339			if ((*endp)[2] == 'B')
340				(*endp) += 3;
341			else
342				(*endp) += 2;
343		}
344	}
345	return result;
346}
347
348
349static int parse_num(size_t *num, const char *token)
350{
351	char *endp;
352	size_t n;
353
354	n = (size_t) ustrtoul(token, &endp, 0);
355	if (*endp)
356		return -EINVAL;
357
358	*num = n;
359	return 0;
360}
361
362
363static inline void kill_final_newline(char *str)
364{
365	char *newline = strrchr(str, '\n');
366	if (newline && !newline[1])
367		*newline = 0;
368}
369
370
371#define parse_err(fmt, args...) do {	\
372	ERROR(fmt, ## args);		\
373	return 0;			\
374} while (0)
375
376#ifndef MODULE
377static int block2mtd_init_called = 0;
378static char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */
379#endif
380
381
382static int block2mtd_setup2(const char *val)
383{
384	char buf[80 + 12]; /* 80 for device, 12 for erase size */
385	char *str = buf;
386	char *token[2];
387	char *name;
388	size_t erase_size = PAGE_SIZE;
389	int i, ret;
390
391	if (strnlen(val, sizeof(buf)) >= sizeof(buf))
392		parse_err("parameter too long");
393
394	strcpy(str, val);
395	kill_final_newline(str);
396
397	for (i = 0; i < 2; i++)
398		token[i] = strsep(&str, ",");
399
400	if (str)
401		parse_err("too many arguments");
402
403	if (!token[0])
404		parse_err("no argument");
405
406	name = token[0];
407	if (strlen(name) + 1 > 80)
408		parse_err("device name too long");
409
410	if (token[1]) {
411		ret = parse_num(&erase_size, token[1]);
412		if (ret) {
413			parse_err("illegal erase size");
414		}
415	}
416
417	add_device(name, erase_size);
418
419	return 0;
420}
421
422
423static int block2mtd_setup(const char *val, struct kernel_param *kp)
424{
425#ifdef MODULE
426	return block2mtd_setup2(val);
427#else
428	/* If more parameters are later passed in via
429	   /sys/module/block2mtd/parameters/block2mtd
430	   and block2mtd_init() has already been called,
431	   we can parse the argument now. */
432
433	if (block2mtd_init_called)
434		return block2mtd_setup2(val);
435
436	/* During early boot stage, we only save the parameters
437	   here. We must parse them later: if the param passed
438	   from kernel boot command line, block2mtd_setup() is
439	   called so early that it is not possible to resolve
440	   the device (even kmalloc() fails). Deter that work to
441	   block2mtd_setup2(). */
442
443	strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
444
445	return 0;
446#endif
447}
448
449
450module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
451MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
452
453static int __init block2mtd_init(void)
454{
455	int ret = 0;
456	INFO("version " VERSION);
457
458#ifndef MODULE
459	if (strlen(block2mtd_paramline))
460		ret = block2mtd_setup2(block2mtd_paramline);
461	block2mtd_init_called = 1;
462#endif
463
464	return ret;
465}
466
467
468static void __devexit block2mtd_exit(void)
469{
470	struct list_head *pos, *next;
471
472	/* Remove the MTD devices */
473	list_for_each_safe(pos, next, &blkmtd_device_list) {
474		struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
475		block2mtd_sync(&dev->mtd);
476		del_mtd_device(&dev->mtd);
477		INFO("mtd%d: [%s] removed", dev->mtd.index,
478				dev->mtd.name + strlen("block2mtd: "));
479		list_del(&dev->list);
480		block2mtd_free_device(dev);
481	}
482}
483
484
485module_init(block2mtd_init);
486module_exit(block2mtd_exit);
487
488MODULE_LICENSE("GPL");
489MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
490MODULE_DESCRIPTION("Emulate an MTD using a block device");
491