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/config.h>
12 #include <linux/module.h>
14 #include <linux/blkdev.h>
15 #include <linux/bio.h>
16 #include <linux/pagemap.h>
17 #include <linux/list.h>
18 #include <linux/init.h>
19 #include <linux/mtd/mtd.h>
20 #include <linux/buffer_head.h>
21 #include <linux/mutex.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
= (u_long
*)page_address(page
) + PAGE_SIZE
;
115 for (p
=(u_long
*)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
);
240 static int block2mtd_write(struct mtd_info
*mtd
, loff_t to
, size_t len
,
241 size_t *retlen
, const u_char
*buf
)
243 struct block2mtd_dev
*dev
= mtd
->priv
;
250 if (to
+ len
> mtd
->size
)
251 len
= mtd
->size
- to
;
253 mutex_lock(&dev
->write_mutex
);
254 err
= _block2mtd_write(dev
, buf
, to
, len
, retlen
);
255 mutex_unlock(&dev
->write_mutex
);
262 /* sync the device - wait until the write queue is empty */
263 static void block2mtd_sync(struct mtd_info
*mtd
)
265 struct block2mtd_dev
*dev
= mtd
->priv
;
266 sync_blockdev(dev
->blkdev
);
271 static void block2mtd_free_device(struct block2mtd_dev
*dev
)
276 kfree(dev
->mtd
.name
);
279 invalidate_inode_pages(dev
->blkdev
->bd_inode
->i_mapping
);
280 close_bdev_excl(dev
->blkdev
);
287 /* FIXME: ensure that mtd->size % erase_size == 0 */
288 static struct block2mtd_dev
*add_device(char *devname
, int erase_size
)
290 struct block_device
*bdev
;
291 struct block2mtd_dev
*dev
;
296 dev
= kmalloc(sizeof(struct block2mtd_dev
), GFP_KERNEL
);
299 memset(dev
, 0, sizeof(*dev
));
301 /* Get a handle on the device */
302 bdev
= open_bdev_excl(devname
, O_RDWR
, NULL
);
304 ERROR("error: cannot open device %s", devname
);
309 if (MAJOR(bdev
->bd_dev
) == MTD_BLOCK_MAJOR
) {
310 ERROR("attempting to use an MTD device as a block device");
314 mutex_init(&dev
->write_mutex
);
316 /* Setup the MTD structure */
317 /* make the name contain the block device in */
318 dev
->mtd
.name
= kmalloc(sizeof("block2mtd: ") + strlen(devname
),
323 sprintf(dev
->mtd
.name
, "block2mtd: %s", devname
);
325 dev
->mtd
.size
= dev
->blkdev
->bd_inode
->i_size
& PAGE_MASK
;
326 dev
->mtd
.erasesize
= erase_size
;
327 dev
->mtd
.writesize
= 1;
328 dev
->mtd
.type
= MTD_RAM
;
329 dev
->mtd
.flags
= MTD_CAP_RAM
;
330 dev
->mtd
.erase
= block2mtd_erase
;
331 dev
->mtd
.write
= block2mtd_write
;
332 dev
->mtd
.writev
= default_mtd_writev
;
333 dev
->mtd
.sync
= block2mtd_sync
;
334 dev
->mtd
.read
= block2mtd_read
;
336 dev
->mtd
.owner
= THIS_MODULE
;
338 if (add_mtd_device(&dev
->mtd
)) {
339 /* Device didnt get added, so free the entry */
342 list_add(&dev
->list
, &blkmtd_device_list
);
343 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev
->mtd
.index
,
344 dev
->mtd
.name
+ strlen("blkmtd: "),
345 dev
->mtd
.erasesize
>> 10, dev
->mtd
.erasesize
);
349 block2mtd_free_device(dev
);
354 /* This function works similar to reguler strtoul. In addition, it
355 * allows some suffixes for a more human-readable number format:
356 * ki, Ki, kiB, KiB - multiply result with 1024
357 * Mi, MiB - multiply result with 1024^2
358 * Gi, GiB - multiply result with 1024^3
360 static int ustrtoul(const char *cp
, char **endp
, unsigned int base
)
362 unsigned long result
= simple_strtoul(cp
, endp
, base
);
371 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
372 if ((*endp
)[1] == 'i') {
373 if ((*endp
)[2] == 'B')
383 static int parse_num(size_t *num
, const char *token
)
388 n
= (size_t) ustrtoul(token
, &endp
, 0);
397 static int parse_name(char **pname
, const char *token
, size_t limit
)
402 len
= strlen(token
) + 1;
406 name
= kmalloc(len
, GFP_KERNEL
);
417 static inline void kill_final_newline(char *str
)
419 char *newline
= strrchr(str
, '\n');
420 if (newline
&& !newline
[1])
425 #define parse_err(fmt, args...) do { \
426 ERROR("block2mtd: " fmt "\n", ## args); \
430 static int block2mtd_setup(const char *val
, struct kernel_param
*kp
)
432 char buf
[80+12]; /* 80 for device, 12 for erase size */
436 size_t erase_size
= PAGE_SIZE
;
439 if (strnlen(val
, sizeof(buf
)) >= sizeof(buf
))
440 parse_err("parameter too long");
443 kill_final_newline(str
);
445 for (i
= 0; i
< 2; i
++)
446 token
[i
] = strsep(&str
, ",");
449 parse_err("too many arguments");
452 parse_err("no argument");
454 ret
= parse_name(&name
, token
[0], 80);
456 parse_err("out of memory");
458 parse_err("name too long");
463 ret
= parse_num(&erase_size
, token
[1]);
466 parse_err("illegal erase size");
470 add_device(name
, erase_size
);
476 module_param_call(block2mtd
, block2mtd_setup
, NULL
, NULL
, 0200);
477 MODULE_PARM_DESC(block2mtd
, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
479 static int __init
block2mtd_init(void)
481 INFO("version " VERSION
);
486 static void __devexit
block2mtd_exit(void)
488 struct list_head
*pos
, *next
;
490 /* Remove the MTD devices */
491 list_for_each_safe(pos
, next
, &blkmtd_device_list
) {
492 struct block2mtd_dev
*dev
= list_entry(pos
, typeof(*dev
), list
);
493 block2mtd_sync(&dev
->mtd
);
494 del_mtd_device(&dev
->mtd
);
495 INFO("mtd%d: [%s] removed", dev
->mtd
.index
,
496 dev
->mtd
.name
+ strlen("blkmtd: "));
497 list_del(&dev
->list
);
498 block2mtd_free_device(dev
);
503 module_init(block2mtd_init
);
504 module_exit(block2mtd_exit
);
506 MODULE_LICENSE("GPL");
507 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
508 MODULE_DESCRIPTION("Emulate an MTD using a block device");