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/mutex.h>
18 #include <linux/mount.h>
19 #include <linux/slab.h>
21 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
22 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
25 /* Info for the block device */
26 struct block2mtd_dev {
27 struct list_head list;
28 struct block_device *blkdev;
30 struct mutex write_mutex;
34 /* Static info about the MTD, used in cleanup_module */
35 static LIST_HEAD(blkmtd_device_list);
38 static struct page *page_read(struct address_space *mapping, int index)
40 return read_mapping_page(mapping, index, NULL);
43 /* erase a specified part of the device */
44 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
46 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
48 int index = to >> PAGE_SHIFT; // page index
49 int pages = len >> PAGE_SHIFT;
54 page = page_read(mapping, index);
58 max = page_address(page) + PAGE_SIZE;
59 for (p=page_address(page); p<max; p++)
62 memset(page_address(page), 0xff, PAGE_SIZE);
65 balance_dirty_pages_ratelimited(mapping);
69 page_cache_release(page);
75 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
77 struct block2mtd_dev *dev = mtd->priv;
78 size_t from = instr->addr;
79 size_t len = instr->len;
82 instr->state = MTD_ERASING;
83 mutex_lock(&dev->write_mutex);
84 err = _block2mtd_erase(dev, from, len);
85 mutex_unlock(&dev->write_mutex);
87 ERROR("erase failed err = %d", err);
88 instr->state = MTD_ERASE_FAILED;
90 instr->state = MTD_ERASE_DONE;
92 mtd_erase_callback(instr);
97 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
98 size_t *retlen, u_char *buf)
100 struct block2mtd_dev *dev = mtd->priv;
102 int index = from >> PAGE_SHIFT;
103 int offset = from & (PAGE_SIZE-1);
107 if ((offset + len) > PAGE_SIZE)
108 cpylen = PAGE_SIZE - offset; // multiple pages
110 cpylen = len; // this page
113 page = page_read(dev->blkdev->bd_inode->i_mapping, index);
115 return PTR_ERR(page);
117 memcpy(buf, page_address(page) + offset, cpylen);
118 page_cache_release(page);
130 /* write data to the underlying device */
131 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
132 loff_t to, size_t len, size_t *retlen)
135 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
136 int index = to >> PAGE_SHIFT; // page index
137 int offset = to & ~PAGE_MASK; // page offset
141 if ((offset+len) > PAGE_SIZE)
142 cpylen = PAGE_SIZE - offset; // multiple pages
144 cpylen = len; // this page
147 page = page_read(mapping, index);
149 return PTR_ERR(page);
151 if (memcmp(page_address(page)+offset, buf, cpylen)) {
153 memcpy(page_address(page) + offset, buf, cpylen);
154 set_page_dirty(page);
156 balance_dirty_pages_ratelimited(mapping);
158 page_cache_release(page);
171 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
172 size_t *retlen, const u_char *buf)
174 struct block2mtd_dev *dev = mtd->priv;
177 mutex_lock(&dev->write_mutex);
178 err = _block2mtd_write(dev, buf, to, len, retlen);
179 mutex_unlock(&dev->write_mutex);
186 /* sync the device - wait until the write queue is empty */
187 static void block2mtd_sync(struct mtd_info *mtd)
189 struct block2mtd_dev *dev = mtd->priv;
190 sync_blockdev(dev->blkdev);
195 static void block2mtd_free_device(struct block2mtd_dev *dev)
200 kfree(dev->mtd.name);
203 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
205 blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
212 /* FIXME: ensure that mtd->size % erase_size == 0 */
213 static struct block2mtd_dev *add_device(char *devname, int erase_size)
215 const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
216 struct block_device *bdev;
217 struct block2mtd_dev *dev;
223 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
227 /* Get a handle on the device */
228 bdev = blkdev_get_by_path(devname, mode, dev);
232 /* We might not have rootfs mounted at this point. Try
233 to resolve the device name by other means. */
235 dev_t devt = name_to_dev_t(devname);
237 bdev = blkdev_get_by_dev(devt, mode, dev);
242 ERROR("error: cannot open device %s", devname);
247 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
248 ERROR("attempting to use an MTD device as a block device");
252 mutex_init(&dev->write_mutex);
254 /* Setup the MTD structure */
255 /* make the name contain the block device in */
256 name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
260 dev->mtd.name = name;
262 dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
263 dev->mtd.erasesize = erase_size;
264 dev->mtd.writesize = 1;
265 dev->mtd.writebufsize = PAGE_SIZE;
266 dev->mtd.type = MTD_RAM;
267 dev->mtd.flags = MTD_CAP_RAM;
268 dev->mtd._erase = block2mtd_erase;
269 dev->mtd._write = block2mtd_write;
270 dev->mtd._sync = block2mtd_sync;
271 dev->mtd._read = block2mtd_read;
273 dev->mtd.owner = THIS_MODULE;
275 if (mtd_device_register(&dev->mtd, NULL, 0)) {
276 /* Device didn't get added, so free the entry */
279 list_add(&dev->list, &blkmtd_device_list);
280 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
281 dev->mtd.name + strlen("block2mtd: "),
282 dev->mtd.erasesize >> 10, dev->mtd.erasesize);
286 block2mtd_free_device(dev);
291 /* This function works similar to reguler strtoul. In addition, it
292 * allows some suffixes for a more human-readable number format:
293 * ki, Ki, kiB, KiB - multiply result with 1024
294 * Mi, MiB - multiply result with 1024^2
295 * Gi, GiB - multiply result with 1024^3
297 static int ustrtoul(const char *cp, char **endp, unsigned int base)
299 unsigned long result = simple_strtoul(cp, endp, base);
308 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
309 if ((*endp)[1] == 'i') {
310 if ((*endp)[2] == 'B')
320 static int parse_num(size_t *num, const char *token)
325 n = (size_t) ustrtoul(token, &endp, 0);
334 static inline void kill_final_newline(char *str)
336 char *newline = strrchr(str, '\n');
337 if (newline && !newline[1])
342 #define parse_err(fmt, args...) do { \
343 ERROR(fmt, ## args); \
348 static int block2mtd_init_called = 0;
349 static char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */
353 static int block2mtd_setup2(const char *val)
355 char buf[80 + 12]; /* 80 for device, 12 for erase size */
359 size_t erase_size = PAGE_SIZE;
362 if (strnlen(val, sizeof(buf)) >= sizeof(buf))
363 parse_err("parameter too long");
366 kill_final_newline(str);
368 for (i = 0; i < 2; i++)
369 token[i] = strsep(&str, ",");
372 parse_err("too many arguments");
375 parse_err("no argument");
378 if (strlen(name) + 1 > 80)
379 parse_err("device name too long");
382 ret = parse_num(&erase_size, token[1]);
384 parse_err("illegal erase size");
388 add_device(name, erase_size);
394 static int block2mtd_setup(const char *val, struct kernel_param *kp)
397 return block2mtd_setup2(val);
399 /* If more parameters are later passed in via
400 /sys/module/block2mtd/parameters/block2mtd
401 and block2mtd_init() has already been called,
402 we can parse the argument now. */
404 if (block2mtd_init_called)
405 return block2mtd_setup2(val);
407 /* During early boot stage, we only save the parameters
408 here. We must parse them later: if the param passed
409 from kernel boot command line, block2mtd_setup() is
410 called so early that it is not possible to resolve
411 the device (even kmalloc() fails). Deter that work to
412 block2mtd_setup2(). */
414 strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
421 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
422 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
424 static int __init block2mtd_init(void)
429 if (strlen(block2mtd_paramline))
430 ret = block2mtd_setup2(block2mtd_paramline);
431 block2mtd_init_called = 1;
438 static void block2mtd_exit(void)
440 struct list_head *pos, *next;
442 /* Remove the MTD devices */
443 list_for_each_safe(pos, next, &blkmtd_device_list) {
444 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
445 block2mtd_sync(&dev->mtd);
446 mtd_device_unregister(&dev->mtd);
447 INFO("mtd%d: [%s] removed", dev->mtd.index,
448 dev->mtd.name + strlen("block2mtd: "));
449 list_del(&dev->list);
450 block2mtd_free_device(dev);
455 module_init(block2mtd_init);
456 module_exit(block2mtd_exit);
458 MODULE_LICENSE("GPL");
459 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
460 MODULE_DESCRIPTION("Emulate an MTD using a block device");