2 * $Id: block2mtd.c,v 1.23 2005/01/05 17:05:46 dwmw2 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 Gareth Bult <Gareth@Encryptec.net>
8 * Copyright (C) 2004,2005 Jörn Engel <joern@wh.fh-wedel.de>
12 #include <linux/config.h>
13 #include <linux/module.h>
15 #include <linux/blkdev.h>
16 #include <linux/bio.h>
17 #include <linux/pagemap.h>
18 #include <linux/list.h>
19 #include <linux/init.h>
20 #include <linux/mtd/mtd.h>
21 #include <linux/buffer_head.h>
23 #define VERSION "$Revision: 1.23 $"
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 semaphore 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 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 //do_page_cache_readahead(mapping, index, XXX, 64);
93 cache_readahead(mapping, index);
94 return read_cache_page(mapping, index, filler, NULL);
98 /* erase a specified part of the device */
99 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
101 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
103 int index = to >> PAGE_SHIFT; // page index
104 int pages = len >> PAGE_SHIFT;
109 page = page_readahead(mapping, index);
113 return PTR_ERR(page);
115 max = (u_long*)page_address(page) + PAGE_SIZE;
116 for (p=(u_long*)page_address(page); p<max; p++)
119 memset(page_address(page), 0xff, PAGE_SIZE);
120 set_page_dirty(page);
125 page_cache_release(page);
131 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
133 struct block2mtd_dev *dev = mtd->priv;
134 size_t from = instr->addr;
135 size_t len = instr->len;
138 instr->state = MTD_ERASING;
139 down(&dev->write_mutex);
140 err = _block2mtd_erase(dev, from, len);
141 up(&dev->write_mutex);
143 ERROR("erase failed err = %d", err);
144 instr->state = MTD_ERASE_FAILED;
146 instr->state = MTD_ERASE_DONE;
148 instr->state = MTD_ERASE_DONE;
149 mtd_erase_callback(instr);
154 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
155 size_t *retlen, u_char *buf)
157 struct block2mtd_dev *dev = mtd->priv;
159 int index = from >> PAGE_SHIFT;
160 int offset = from & (PAGE_SHIFT-1);
163 if (from > mtd->size)
165 if (from + len > mtd->size)
166 len = mtd->size - from;
172 if ((offset + len) > PAGE_SIZE)
173 cpylen = PAGE_SIZE - offset; // multiple pages
175 cpylen = len; // this page
179 page = page_readahead(dev->blkdev->bd_inode->i_mapping, index);
183 return PTR_ERR(page);
185 memcpy(buf, page_address(page) + offset, cpylen);
186 page_cache_release(page);
198 /* write data to the underlying device */
199 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
200 loff_t to, size_t len, size_t *retlen)
203 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
204 int index = to >> PAGE_SHIFT; // page index
205 int offset = to & ~PAGE_MASK; // page offset
211 if ((offset+len) > PAGE_SIZE)
212 cpylen = PAGE_SIZE - offset; // multiple pages
214 cpylen = len; // this page
218 page = page_readahead(mapping, index);
222 return PTR_ERR(page);
224 if (memcmp(page_address(page)+offset, buf, cpylen)) {
226 memcpy(page_address(page) + offset, buf, cpylen);
227 set_page_dirty(page);
230 page_cache_release(page);
241 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
242 size_t *retlen, const u_char *buf)
244 struct block2mtd_dev *dev = mtd->priv;
251 if (to + len > mtd->size)
252 len = mtd->size - to;
254 down(&dev->write_mutex);
255 err = _block2mtd_write(dev, buf, to, len, retlen);
256 up(&dev->write_mutex);
263 /* sync the device - wait until the write queue is empty */
264 static void block2mtd_sync(struct mtd_info *mtd)
266 struct block2mtd_dev *dev = mtd->priv;
267 sync_blockdev(dev->blkdev);
272 static void block2mtd_free_device(struct block2mtd_dev *dev)
277 kfree(dev->mtd.name);
280 invalidate_inode_pages(dev->blkdev->bd_inode->i_mapping);
281 close_bdev_excl(dev->blkdev);
288 /* FIXME: ensure that mtd->size % erase_size == 0 */
289 static struct block2mtd_dev *add_device(char *devname, int erase_size)
291 struct block_device *bdev;
292 struct block2mtd_dev *dev;
297 dev = kmalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
300 memset(dev, 0, sizeof(*dev));
302 /* Get a handle on the device */
303 bdev = open_bdev_excl(devname, O_RDWR, NULL);
305 ERROR("error: cannot open device %s", devname);
310 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
311 ERROR("attempting to use an MTD device as a block device");
315 init_MUTEX(&dev->write_mutex);
317 /* Setup the MTD structure */
318 /* make the name contain the block device in */
319 dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
324 sprintf(dev->mtd.name, "block2mtd: %s", devname);
326 dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
327 dev->mtd.erasesize = erase_size;
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;
335 dev->mtd.readv = default_mtd_readv;
337 dev->mtd.owner = THIS_MODULE;
339 if (add_mtd_device(&dev->mtd)) {
340 /* Device didnt get added, so free the entry */
343 list_add(&dev->list, &blkmtd_device_list);
344 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
345 dev->mtd.name + strlen("blkmtd: "),
346 dev->mtd.erasesize >> 10, dev->mtd.erasesize);
350 block2mtd_free_device(dev);
355 static int ustrtoul(const char *cp, char **endp, unsigned int base)
357 unsigned long result = simple_strtoul(cp, endp, base);
365 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
366 if ((*endp)[1] == 'i')
373 static int parse_num32(u32 *num32, const char *token)
378 n = ustrtoul(token, &endp, 0);
387 static int parse_name(char **pname, const char *token, size_t limit)
392 len = strlen(token) + 1;
396 name = kmalloc(len, GFP_KERNEL);
407 static inline void kill_final_newline(char *str)
409 char *newline = strrchr(str, '\n');
410 if (newline && !newline[1])
415 #define parse_err(fmt, args...) do { \
416 ERROR("block2mtd: " fmt "\n", ## args); \
420 static int block2mtd_setup(const char *val, struct kernel_param *kp)
422 char buf[80+12], *str=buf; /* 80 for device, 12 for erase size */
425 u32 erase_size = PAGE_SIZE;
428 if (strnlen(val, sizeof(buf)) >= sizeof(buf))
429 parse_err("parameter too long");
432 kill_final_newline(str);
435 token[i] = strsep(&str, ",");
438 parse_err("too many arguments");
441 parse_err("no argument");
443 ret = parse_name(&name, token[0], 80);
445 parse_err("out of memory");
447 parse_err("name too long");
452 ret = parse_num32(&erase_size, token[1]);
454 parse_err("illegal erase size");
457 add_device(name, erase_size);
463 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
464 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
466 static int __init block2mtd_init(void)
468 INFO("version " VERSION);
473 static void __devexit block2mtd_exit(void)
475 struct list_head *pos, *next;
477 /* Remove the MTD devices */
478 list_for_each_safe(pos, next, &blkmtd_device_list) {
479 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
480 block2mtd_sync(&dev->mtd);
481 del_mtd_device(&dev->mtd);
482 INFO("mtd%d: [%s] removed", dev->mtd.index,
483 dev->mtd.name + strlen("blkmtd: "));
484 list_del(&dev->list);
485 block2mtd_free_device(dev);
490 module_init(block2mtd_init);
491 module_exit(block2mtd_exit);
493 MODULE_LICENSE("GPL");
494 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
495 MODULE_DESCRIPTION("Emulate an MTD using a block device");