2 * block2mtd.c - create an mtd from a block device
4 * Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk>
5 * Copyright (C) 2004-2006 Joern Engel <joern@wh.fh-wedel.de>
9 #include <linux/module.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 #include <linux/slab.h>
22 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
23 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
26 /* Info for the block device */
27 struct block2mtd_dev
{
28 struct list_head list
;
29 struct block_device
*blkdev
;
31 struct mutex write_mutex
;
35 /* Static info about the MTD, used in cleanup_module */
36 static LIST_HEAD(blkmtd_device_list
);
39 static struct page
*page_read(struct address_space
*mapping
, int index
)
41 return read_mapping_page(mapping
, index
, NULL
);
44 /* erase a specified part of the device */
45 static int _block2mtd_erase(struct block2mtd_dev
*dev
, loff_t to
, size_t len
)
47 struct address_space
*mapping
= dev
->blkdev
->bd_inode
->i_mapping
;
49 int index
= to
>> PAGE_SHIFT
; // page index
50 int pages
= len
>> PAGE_SHIFT
;
55 page
= page_read(mapping
, index
);
61 max
= page_address(page
) + PAGE_SIZE
;
62 for (p
=page_address(page
); p
<max
; p
++)
65 memset(page_address(page
), 0xff, PAGE_SIZE
);
71 page_cache_release(page
);
77 static int block2mtd_erase(struct mtd_info
*mtd
, struct erase_info
*instr
)
79 struct block2mtd_dev
*dev
= mtd
->priv
;
80 size_t from
= instr
->addr
;
81 size_t len
= instr
->len
;
84 instr
->state
= MTD_ERASING
;
85 mutex_lock(&dev
->write_mutex
);
86 err
= _block2mtd_erase(dev
, from
, len
);
87 mutex_unlock(&dev
->write_mutex
);
89 ERROR("erase failed err = %d", err
);
90 instr
->state
= MTD_ERASE_FAILED
;
92 instr
->state
= MTD_ERASE_DONE
;
94 instr
->state
= MTD_ERASE_DONE
;
95 mtd_erase_callback(instr
);
100 static int block2mtd_read(struct mtd_info
*mtd
, loff_t from
, size_t len
,
101 size_t *retlen
, u_char
*buf
)
103 struct block2mtd_dev
*dev
= mtd
->priv
;
105 int index
= from
>> PAGE_SHIFT
;
106 int offset
= from
& (PAGE_SIZE
-1);
109 if (from
> mtd
->size
)
111 if (from
+ len
> mtd
->size
)
112 len
= mtd
->size
- from
;
118 if ((offset
+ len
) > PAGE_SIZE
)
119 cpylen
= PAGE_SIZE
- offset
; // multiple pages
121 cpylen
= len
; // this page
124 page
= page_read(dev
->blkdev
->bd_inode
->i_mapping
, index
);
128 return PTR_ERR(page
);
130 memcpy(buf
, page_address(page
) + offset
, cpylen
);
131 page_cache_release(page
);
143 /* write data to the underlying device */
144 static int _block2mtd_write(struct block2mtd_dev
*dev
, const u_char
*buf
,
145 loff_t to
, size_t len
, size_t *retlen
)
148 struct address_space
*mapping
= dev
->blkdev
->bd_inode
->i_mapping
;
149 int index
= to
>> PAGE_SHIFT
; // page index
150 int offset
= to
& ~PAGE_MASK
; // page offset
156 if ((offset
+len
) > PAGE_SIZE
)
157 cpylen
= PAGE_SIZE
- offset
; // multiple pages
159 cpylen
= len
; // this page
162 page
= page_read(mapping
, index
);
166 return PTR_ERR(page
);
168 if (memcmp(page_address(page
)+offset
, buf
, cpylen
)) {
170 memcpy(page_address(page
) + offset
, buf
, cpylen
);
171 set_page_dirty(page
);
174 page_cache_release(page
);
187 static int block2mtd_write(struct mtd_info
*mtd
, loff_t to
, size_t len
,
188 size_t *retlen
, const u_char
*buf
)
190 struct block2mtd_dev
*dev
= mtd
->priv
;
197 if (to
+ len
> mtd
->size
)
198 len
= mtd
->size
- to
;
200 mutex_lock(&dev
->write_mutex
);
201 err
= _block2mtd_write(dev
, buf
, to
, len
, retlen
);
202 mutex_unlock(&dev
->write_mutex
);
209 /* sync the device - wait until the write queue is empty */
210 static void block2mtd_sync(struct mtd_info
*mtd
)
212 struct block2mtd_dev
*dev
= mtd
->priv
;
213 sync_blockdev(dev
->blkdev
);
218 static void block2mtd_free_device(struct block2mtd_dev
*dev
)
223 kfree(dev
->mtd
.name
);
226 invalidate_mapping_pages(dev
->blkdev
->bd_inode
->i_mapping
,
228 close_bdev_exclusive(dev
->blkdev
, FMODE_READ
|FMODE_WRITE
);
235 /* FIXME: ensure that mtd->size % erase_size == 0 */
236 static struct block2mtd_dev
*add_device(char *devname
, int erase_size
)
238 struct block_device
*bdev
;
239 struct block2mtd_dev
*dev
;
245 dev
= kzalloc(sizeof(struct block2mtd_dev
), GFP_KERNEL
);
249 /* Get a handle on the device */
250 bdev
= open_bdev_exclusive(devname
, FMODE_READ
|FMODE_WRITE
, NULL
);
254 /* We might not have rootfs mounted at this point. Try
255 to resolve the device name by other means. */
257 dev_t devt
= name_to_dev_t(devname
);
259 bdev
= open_by_devnum(devt
, FMODE_WRITE
| FMODE_READ
);
265 ERROR("error: cannot open device %s", devname
);
270 if (MAJOR(bdev
->bd_dev
) == MTD_BLOCK_MAJOR
) {
271 ERROR("attempting to use an MTD device as a block device");
275 mutex_init(&dev
->write_mutex
);
277 /* Setup the MTD structure */
278 /* make the name contain the block device in */
279 name
= kasprintf(GFP_KERNEL
, "block2mtd: %s", devname
);
283 dev
->mtd
.name
= name
;
285 dev
->mtd
.size
= dev
->blkdev
->bd_inode
->i_size
& PAGE_MASK
;
286 dev
->mtd
.erasesize
= erase_size
;
287 dev
->mtd
.writesize
= 1;
288 dev
->mtd
.type
= MTD_RAM
;
289 dev
->mtd
.flags
= MTD_CAP_RAM
;
290 dev
->mtd
.erase
= block2mtd_erase
;
291 dev
->mtd
.write
= block2mtd_write
;
292 dev
->mtd
.writev
= default_mtd_writev
;
293 dev
->mtd
.sync
= block2mtd_sync
;
294 dev
->mtd
.read
= block2mtd_read
;
296 dev
->mtd
.owner
= THIS_MODULE
;
298 if (add_mtd_device(&dev
->mtd
)) {
299 /* Device didnt get added, so free the entry */
302 list_add(&dev
->list
, &blkmtd_device_list
);
303 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev
->mtd
.index
,
304 dev
->mtd
.name
+ strlen("block2mtd: "),
305 dev
->mtd
.erasesize
>> 10, dev
->mtd
.erasesize
);
309 block2mtd_free_device(dev
);
314 /* This function works similar to reguler strtoul. In addition, it
315 * allows some suffixes for a more human-readable number format:
316 * ki, Ki, kiB, KiB - multiply result with 1024
317 * Mi, MiB - multiply result with 1024^2
318 * Gi, GiB - multiply result with 1024^3
320 static int ustrtoul(const char *cp
, char **endp
, unsigned int base
)
322 unsigned long result
= simple_strtoul(cp
, endp
, base
);
331 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
332 if ((*endp
)[1] == 'i') {
333 if ((*endp
)[2] == 'B')
343 static int parse_num(size_t *num
, const char *token
)
348 n
= (size_t) ustrtoul(token
, &endp
, 0);
357 static inline void kill_final_newline(char *str
)
359 char *newline
= strrchr(str
, '\n');
360 if (newline
&& !newline
[1])
365 #define parse_err(fmt, args...) do { \
366 ERROR(fmt, ## args); \
371 static int block2mtd_init_called
= 0;
372 static char block2mtd_paramline
[80 + 12]; /* 80 for device, 12 for erase size */
376 static int block2mtd_setup2(const char *val
)
378 char buf
[80 + 12]; /* 80 for device, 12 for erase size */
382 size_t erase_size
= PAGE_SIZE
;
385 if (strnlen(val
, sizeof(buf
)) >= sizeof(buf
))
386 parse_err("parameter too long");
389 kill_final_newline(str
);
391 for (i
= 0; i
< 2; i
++)
392 token
[i
] = strsep(&str
, ",");
395 parse_err("too many arguments");
398 parse_err("no argument");
401 if (strlen(name
) + 1 > 80)
402 parse_err("device name too long");
405 ret
= parse_num(&erase_size
, token
[1]);
407 parse_err("illegal erase size");
411 add_device(name
, erase_size
);
417 static int block2mtd_setup(const char *val
, struct kernel_param
*kp
)
420 return block2mtd_setup2(val
);
422 /* If more parameters are later passed in via
423 /sys/module/block2mtd/parameters/block2mtd
424 and block2mtd_init() has already been called,
425 we can parse the argument now. */
427 if (block2mtd_init_called
)
428 return block2mtd_setup2(val
);
430 /* During early boot stage, we only save the parameters
431 here. We must parse them later: if the param passed
432 from kernel boot command line, block2mtd_setup() is
433 called so early that it is not possible to resolve
434 the device (even kmalloc() fails). Deter that work to
435 block2mtd_setup2(). */
437 strlcpy(block2mtd_paramline
, val
, sizeof(block2mtd_paramline
));
444 module_param_call(block2mtd
, block2mtd_setup
, NULL
, NULL
, 0200);
445 MODULE_PARM_DESC(block2mtd
, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
447 static int __init
block2mtd_init(void)
452 if (strlen(block2mtd_paramline
))
453 ret
= block2mtd_setup2(block2mtd_paramline
);
454 block2mtd_init_called
= 1;
461 static void __devexit
block2mtd_exit(void)
463 struct list_head
*pos
, *next
;
465 /* Remove the MTD devices */
466 list_for_each_safe(pos
, next
, &blkmtd_device_list
) {
467 struct block2mtd_dev
*dev
= list_entry(pos
, typeof(*dev
), list
);
468 block2mtd_sync(&dev
->mtd
);
469 del_mtd_device(&dev
->mtd
);
470 INFO("mtd%d: [%s] removed", dev
->mtd
.index
,
471 dev
->mtd
.name
+ strlen("block2mtd: "));
472 list_del(&dev
->list
);
473 block2mtd_free_device(dev
);
478 module_init(block2mtd_init
);
479 module_exit(block2mtd_exit
);
481 MODULE_LICENSE("GPL");
482 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
483 MODULE_DESCRIPTION("Emulate an MTD using a block device");