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 */
31 struct 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 */
40 static LIST_HEAD(blkmtd_device_list);
41
42
43 static 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 */
49 static 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 }
81 static 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
104 static 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 */
148 static 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
191 static 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 */
214 static 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
222 static 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 */
240 static struct block2mtd_dev *add_device(char *devname, int erase_size)
241 {
242 struct block_device *bdev;
243 struct block2mtd_dev *dev;
244
245 if (!devname)
246 return NULL;
247
248 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
249 if (!dev)
250 return NULL;
251
252 /* Get a handle on the device */
253 bdev = open_bdev_excl(devname, O_RDWR, NULL);
254 #ifndef MODULE
255 if (IS_ERR(bdev)) {
256
257 /* We might not have rootfs mounted at this point. Try
258 to resolve the device name by other means. */
259
260 dev_t devt = name_to_dev_t(devname);
261 if (devt) {
262 bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);
263 }
264 }
265 #endif
266
267 if (IS_ERR(bdev)) {
268 ERROR("error: cannot open device %s", devname);
269 goto devinit_err;
270 }
271 dev->blkdev = bdev;
272
273 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
274 ERROR("attempting to use an MTD device as a block device");
275 goto devinit_err;
276 }
277
278 mutex_init(&dev->write_mutex);
279
280 /* Setup the MTD structure */
281 /* make the name contain the block device in */
282 dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
283 GFP_KERNEL);
284 if (!dev->mtd.name)
285 goto devinit_err;
286
287 sprintf(dev->mtd.name, "block2mtd: %s", devname);
288
289 dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
290 dev->mtd.erasesize = erase_size;
291 dev->mtd.writesize = 1;
292 dev->mtd.type = MTD_RAM;
293 dev->mtd.flags = MTD_CAP_RAM;
294 dev->mtd.erase = block2mtd_erase;
295 dev->mtd.write = block2mtd_write;
296 dev->mtd.writev = default_mtd_writev;
297 dev->mtd.sync = block2mtd_sync;
298 dev->mtd.read = block2mtd_read;
299 dev->mtd.priv = dev;
300 dev->mtd.owner = THIS_MODULE;
301
302 if (add_mtd_device(&dev->mtd)) {
303 /* Device didnt get added, so free the entry */
304 goto devinit_err;
305 }
306 list_add(&dev->list, &blkmtd_device_list);
307 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
308 dev->mtd.name + strlen("blkmtd: "),
309 dev->mtd.erasesize >> 10, dev->mtd.erasesize);
310 return dev;
311
312 devinit_err:
313 block2mtd_free_device(dev);
314 return NULL;
315 }
316
317
318 /* This function works similar to reguler strtoul. In addition, it
319 * allows some suffixes for a more human-readable number format:
320 * ki, Ki, kiB, KiB - multiply result with 1024
321 * Mi, MiB - multiply result with 1024^2
322 * Gi, GiB - multiply result with 1024^3
323 */
324 static int ustrtoul(const char *cp, char **endp, unsigned int base)
325 {
326 unsigned long result = simple_strtoul(cp, endp, base);
327 switch (**endp) {
328 case 'G' :
329 result *= 1024;
330 case 'M':
331 result *= 1024;
332 case 'K':
333 case 'k':
334 result *= 1024;
335 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
336 if ((*endp)[1] == 'i') {
337 if ((*endp)[2] == 'B')
338 (*endp) += 3;
339 else
340 (*endp) += 2;
341 }
342 }
343 return result;
344 }
345
346
347 static int parse_num(size_t *num, const char *token)
348 {
349 char *endp;
350 size_t n;
351
352 n = (size_t) ustrtoul(token, &endp, 0);
353 if (*endp)
354 return -EINVAL;
355
356 *num = n;
357 return 0;
358 }
359
360
361 static inline void kill_final_newline(char *str)
362 {
363 char *newline = strrchr(str, '\n');
364 if (newline && !newline[1])
365 *newline = 0;
366 }
367
368
369 #define parse_err(fmt, args...) do { \
370 ERROR("block2mtd: " fmt "\n", ## args); \
371 return 0; \
372 } while (0)
373
374 #ifndef MODULE
375 static int block2mtd_init_called = 0;
376 static char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */
377 #endif
378
379
380 static int block2mtd_setup2(const char *val)
381 {
382 char buf[80 + 12]; /* 80 for device, 12 for erase size */
383 char *str = buf;
384 char *token[2];
385 char *name;
386 size_t erase_size = PAGE_SIZE;
387 int i, ret;
388
389 if (strnlen(val, sizeof(buf)) >= sizeof(buf))
390 parse_err("parameter too long");
391
392 strcpy(str, val);
393 kill_final_newline(str);
394
395 for (i = 0; i < 2; i++)
396 token[i] = strsep(&str, ",");
397
398 if (str)
399 parse_err("too many arguments");
400
401 if (!token[0])
402 parse_err("no argument");
403
404 name = token[0];
405 if (strlen(name) + 1 > 80)
406 parse_err("device name too long");
407
408 if (token[1]) {
409 ret = parse_num(&erase_size, token[1]);
410 if (ret) {
411 parse_err("illegal erase size");
412 }
413 }
414
415 add_device(name, erase_size);
416
417 return 0;
418 }
419
420
421 static int block2mtd_setup(const char *val, struct kernel_param *kp)
422 {
423 #ifdef MODULE
424 return block2mtd_setup2(val);
425 #else
426 /* If more parameters are later passed in via
427 /sys/module/block2mtd/parameters/block2mtd
428 and block2mtd_init() has already been called,
429 we can parse the argument now. */
430
431 if (block2mtd_init_called)
432 return block2mtd_setup2(val);
433
434 /* During early boot stage, we only save the parameters
435 here. We must parse them later: if the param passed
436 from kernel boot command line, block2mtd_setup() is
437 called so early that it is not possible to resolve
438 the device (even kmalloc() fails). Deter that work to
439 block2mtd_setup2(). */
440
441 strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
442
443 return 0;
444 #endif
445 }
446
447
448 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
449 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
450
451 static int __init block2mtd_init(void)
452 {
453 int ret = 0;
454 INFO("version " VERSION);
455
456 #ifndef MODULE
457 if (strlen(block2mtd_paramline))
458 ret = block2mtd_setup2(block2mtd_paramline);
459 block2mtd_init_called = 1;
460 #endif
461
462 return ret;
463 }
464
465
466 static void __devexit block2mtd_exit(void)
467 {
468 struct list_head *pos, *next;
469
470 /* Remove the MTD devices */
471 list_for_each_safe(pos, next, &blkmtd_device_list) {
472 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
473 block2mtd_sync(&dev->mtd);
474 del_mtd_device(&dev->mtd);
475 INFO("mtd%d: [%s] removed", dev->mtd.index,
476 dev->mtd.name + strlen("blkmtd: "));
477 list_del(&dev->list);
478 block2mtd_free_device(dev);
479 }
480 }
481
482
483 module_init(block2mtd_init);
484 module_exit(block2mtd_exit);
485
486 MODULE_LICENSE("GPL");
487 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
488 MODULE_DESCRIPTION("Emulate an MTD using a block device");
489
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