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