2 * $Id: block2mtd.c,v 1.30 2005/11/29 14:48:32 gleixner Exp $
4 * block2mtd.c - create an mtd from a block device
6 * Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk>
7 * Copyright (C) 2004-2006 Jörn Engel <joern@wh.fh-wedel.de>
11 #include <linux/module.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>
23 #define VERSION "$Revision: 1.30 $"
26 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
27 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
30 /* Info for the block device */
31 struct block2mtd_dev
{
32 struct list_head list
;
33 struct block_device
*blkdev
;
35 struct mutex write_mutex
;
39 /* Static info about the MTD, used in cleanup_module */
40 static LIST_HEAD(blkmtd_device_list
);
43 #define PAGE_READAHEAD 64
44 static void cache_readahead(struct address_space
*mapping
, int index
)
46 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
49 unsigned long end_index
;
52 struct inode
*inode
= mapping
->host
;
53 loff_t isize
= i_size_read(inode
);
56 INFO("iSize=0 in cache_readahead\n");
60 end_index
= ((isize
- 1) >> PAGE_CACHE_SHIFT
);
62 read_lock_irq(&mapping
->tree_lock
);
63 for (i
= 0; i
< PAGE_READAHEAD
; i
++) {
65 if (pagei
> end_index
) {
66 INFO("Overrun end of disk in cache readahead\n");
69 page
= radix_tree_lookup(&mapping
->page_tree
, pagei
);
74 read_unlock_irq(&mapping
->tree_lock
);
75 page
= page_cache_alloc_cold(mapping
);
76 read_lock_irq(&mapping
->tree_lock
);
80 list_add(&page
->lru
, &page_pool
);
83 read_unlock_irq(&mapping
->tree_lock
);
85 read_cache_pages(mapping
, &page_pool
, filler
, NULL
);
89 static struct page
* page_readahead(struct address_space
*mapping
, int index
)
91 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
92 cache_readahead(mapping
, index
);
93 return read_cache_page(mapping
, index
, filler
, NULL
);
97 /* erase a specified part of the device */
98 static int _block2mtd_erase(struct block2mtd_dev
*dev
, loff_t to
, size_t len
)
100 struct address_space
*mapping
= dev
->blkdev
->bd_inode
->i_mapping
;
102 int index
= to
>> PAGE_SHIFT
; // page index
103 int pages
= len
>> PAGE_SHIFT
;
108 page
= page_readahead(mapping
, index
);
112 return PTR_ERR(page
);
114 max
= page_address(page
) + PAGE_SIZE
;
115 for (p
=page_address(page
); p
<max
; p
++)
118 memset(page_address(page
), 0xff, PAGE_SIZE
);
119 set_page_dirty(page
);
124 page_cache_release(page
);
130 static int block2mtd_erase(struct mtd_info
*mtd
, struct erase_info
*instr
)
132 struct block2mtd_dev
*dev
= mtd
->priv
;
133 size_t from
= instr
->addr
;
134 size_t len
= instr
->len
;
137 instr
->state
= MTD_ERASING
;
138 mutex_lock(&dev
->write_mutex
);
139 err
= _block2mtd_erase(dev
, from
, len
);
140 mutex_unlock(&dev
->write_mutex
);
142 ERROR("erase failed err = %d", err
);
143 instr
->state
= MTD_ERASE_FAILED
;
145 instr
->state
= MTD_ERASE_DONE
;
147 instr
->state
= MTD_ERASE_DONE
;
148 mtd_erase_callback(instr
);
153 static int block2mtd_read(struct mtd_info
*mtd
, loff_t from
, size_t len
,
154 size_t *retlen
, u_char
*buf
)
156 struct block2mtd_dev
*dev
= mtd
->priv
;
158 int index
= from
>> PAGE_SHIFT
;
159 int offset
= from
& (PAGE_SIZE
-1);
162 if (from
> mtd
->size
)
164 if (from
+ len
> mtd
->size
)
165 len
= mtd
->size
- from
;
171 if ((offset
+ len
) > PAGE_SIZE
)
172 cpylen
= PAGE_SIZE
- offset
; // multiple pages
174 cpylen
= len
; // this page
178 page
= page_readahead(dev
->blkdev
->bd_inode
->i_mapping
, index
);
182 return PTR_ERR(page
);
184 memcpy(buf
, page_address(page
) + offset
, cpylen
);
185 page_cache_release(page
);
197 /* write data to the underlying device */
198 static int _block2mtd_write(struct block2mtd_dev
*dev
, const u_char
*buf
,
199 loff_t to
, size_t len
, size_t *retlen
)
202 struct address_space
*mapping
= dev
->blkdev
->bd_inode
->i_mapping
;
203 int index
= to
>> PAGE_SHIFT
; // page index
204 int offset
= to
& ~PAGE_MASK
; // page offset
210 if ((offset
+len
) > PAGE_SIZE
)
211 cpylen
= PAGE_SIZE
- offset
; // multiple pages
213 cpylen
= len
; // this page
217 page
= page_readahead(mapping
, index
);
221 return PTR_ERR(page
);
223 if (memcmp(page_address(page
)+offset
, buf
, cpylen
)) {
225 memcpy(page_address(page
) + offset
, buf
, cpylen
);
226 set_page_dirty(page
);
229 page_cache_release(page
);
242 static int block2mtd_write(struct mtd_info
*mtd
, loff_t to
, size_t len
,
243 size_t *retlen
, const u_char
*buf
)
245 struct block2mtd_dev
*dev
= mtd
->priv
;
252 if (to
+ len
> mtd
->size
)
253 len
= mtd
->size
- to
;
255 mutex_lock(&dev
->write_mutex
);
256 err
= _block2mtd_write(dev
, buf
, to
, len
, retlen
);
257 mutex_unlock(&dev
->write_mutex
);
264 /* sync the device - wait until the write queue is empty */
265 static void block2mtd_sync(struct mtd_info
*mtd
)
267 struct block2mtd_dev
*dev
= mtd
->priv
;
268 sync_blockdev(dev
->blkdev
);
273 static void block2mtd_free_device(struct block2mtd_dev
*dev
)
278 kfree(dev
->mtd
.name
);
281 invalidate_mapping_pages(dev
->blkdev
->bd_inode
->i_mapping
,
283 close_bdev_excl(dev
->blkdev
);
290 /* FIXME: ensure that mtd->size % erase_size == 0 */
291 static struct block2mtd_dev
*add_device(char *devname
, int erase_size
)
293 struct block_device
*bdev
;
294 struct block2mtd_dev
*dev
;
299 dev
= kzalloc(sizeof(struct block2mtd_dev
), GFP_KERNEL
);
303 /* Get a handle on the device */
304 bdev
= open_bdev_excl(devname
, O_RDWR
, NULL
);
308 /* We might not have rootfs mounted at this point. Try
309 to resolve the device name by other means. */
311 dev_t dev
= name_to_dev_t(devname
);
313 bdev
= open_by_devnum(dev
, FMODE_WRITE
| FMODE_READ
);
319 ERROR("error: cannot open device %s", devname
);
324 if (MAJOR(bdev
->bd_dev
) == MTD_BLOCK_MAJOR
) {
325 ERROR("attempting to use an MTD device as a block device");
329 mutex_init(&dev
->write_mutex
);
331 /* Setup the MTD structure */
332 /* make the name contain the block device in */
333 dev
->mtd
.name
= kmalloc(sizeof("block2mtd: ") + strlen(devname
),
338 sprintf(dev
->mtd
.name
, "block2mtd: %s", devname
);
340 dev
->mtd
.size
= dev
->blkdev
->bd_inode
->i_size
& PAGE_MASK
;
341 dev
->mtd
.erasesize
= erase_size
;
342 dev
->mtd
.writesize
= 1;
343 dev
->mtd
.type
= MTD_RAM
;
344 dev
->mtd
.flags
= MTD_CAP_RAM
;
345 dev
->mtd
.erase
= block2mtd_erase
;
346 dev
->mtd
.write
= block2mtd_write
;
347 dev
->mtd
.writev
= default_mtd_writev
;
348 dev
->mtd
.sync
= block2mtd_sync
;
349 dev
->mtd
.read
= block2mtd_read
;
351 dev
->mtd
.owner
= THIS_MODULE
;
353 if (add_mtd_device(&dev
->mtd
)) {
354 /* Device didnt get added, so free the entry */
357 list_add(&dev
->list
, &blkmtd_device_list
);
358 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev
->mtd
.index
,
359 dev
->mtd
.name
+ strlen("blkmtd: "),
360 dev
->mtd
.erasesize
>> 10, dev
->mtd
.erasesize
);
364 block2mtd_free_device(dev
);
369 /* This function works similar to reguler strtoul. In addition, it
370 * allows some suffixes for a more human-readable number format:
371 * ki, Ki, kiB, KiB - multiply result with 1024
372 * Mi, MiB - multiply result with 1024^2
373 * Gi, GiB - multiply result with 1024^3
375 static int ustrtoul(const char *cp
, char **endp
, unsigned int base
)
377 unsigned long result
= simple_strtoul(cp
, endp
, base
);
386 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
387 if ((*endp
)[1] == 'i') {
388 if ((*endp
)[2] == 'B')
398 static int parse_num(size_t *num
, const char *token
)
403 n
= (size_t) ustrtoul(token
, &endp
, 0);
412 static inline void kill_final_newline(char *str
)
414 char *newline
= strrchr(str
, '\n');
415 if (newline
&& !newline
[1])
420 #define parse_err(fmt, args...) do { \
421 ERROR("block2mtd: " fmt "\n", ## args); \
426 static int block2mtd_init_called
= 0;
427 static __initdata
char block2mtd_paramline
[80 + 12]; /* 80 for device, 12 for erase size */
431 static int block2mtd_setup2(const char *val
)
433 char buf
[80 + 12]; /* 80 for device, 12 for erase size */
437 size_t erase_size
= PAGE_SIZE
;
440 if (strnlen(val
, sizeof(buf
)) >= sizeof(buf
))
441 parse_err("parameter too long");
444 kill_final_newline(str
);
446 for (i
= 0; i
< 2; i
++)
447 token
[i
] = strsep(&str
, ",");
450 parse_err("too many arguments");
453 parse_err("no argument");
456 if (strlen(name
) + 1 > 80)
457 parse_err("device name too long");
460 ret
= parse_num(&erase_size
, token
[1]);
463 parse_err("illegal erase size");
467 add_device(name
, erase_size
);
473 static int block2mtd_setup(const char *val
, struct kernel_param
*kp
)
476 return block2mtd_setup2(val
);
478 /* If more parameters are later passed in via
479 /sys/module/block2mtd/parameters/block2mtd
480 and block2mtd_init() has already been called,
481 we can parse the argument now. */
483 if (block2mtd_init_called
)
484 return block2mtd_setup2(val
);
486 /* During early boot stage, we only save the parameters
487 here. We must parse them later: if the param passed
488 from kernel boot command line, block2mtd_setup() is
489 called so early that it is not possible to resolve
490 the device (even kmalloc() fails). Deter that work to
491 block2mtd_setup2(). */
493 strlcpy(block2mtd_paramline
, val
, sizeof(block2mtd_paramline
));
500 module_param_call(block2mtd
, block2mtd_setup
, NULL
, NULL
, 0200);
501 MODULE_PARM_DESC(block2mtd
, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
503 static int __init
block2mtd_init(void)
506 INFO("version " VERSION
);
509 if (strlen(block2mtd_paramline
))
510 ret
= block2mtd_setup2(block2mtd_paramline
);
511 block2mtd_init_called
= 1;
518 static void __devexit
block2mtd_exit(void)
520 struct list_head
*pos
, *next
;
522 /* Remove the MTD devices */
523 list_for_each_safe(pos
, next
, &blkmtd_device_list
) {
524 struct block2mtd_dev
*dev
= list_entry(pos
, typeof(*dev
), list
);
525 block2mtd_sync(&dev
->mtd
);
526 del_mtd_device(&dev
->mtd
);
527 INFO("mtd%d: [%s] removed", dev
->mtd
.index
,
528 dev
->mtd
.name
+ strlen("blkmtd: "));
529 list_del(&dev
->list
);
530 block2mtd_free_device(dev
);
535 module_init(block2mtd_init
);
536 module_exit(block2mtd_exit
);
538 MODULE_LICENSE("GPL");
539 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
540 MODULE_DESCRIPTION("Emulate an MTD using a block device");