1 /* 2 * block2mtd.c - create an mtd from a block device 3 * 4 * Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk> 5 * Copyright (C) 2004-2006 Joern Engel <joern@wh.fh-wedel.de> 6 * 7 * Licence: GPL 8 */ 9 #include <linux/module.h> 10 #include <linux/fs.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> 20 21 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args) 22 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args) 23 24 25 /* Info for the block device */ 26 struct block2mtd_dev { 27 struct list_head list; 28 struct block_device *blkdev; 29 struct mtd_info mtd; 30 struct mutex write_mutex; 31 }; 32 33 34 /* Static info about the MTD, used in cleanup_module */ 35 static LIST_HEAD(blkmtd_device_list); 36 37 38 static struct page *page_read(struct address_space *mapping, int index) 39 { 40 return read_mapping_page(mapping, index, NULL); 41 } 42 43 /* erase a specified part of the device */ 44 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len) 45 { 46 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping; 47 struct page *page; 48 int index = to >> PAGE_SHIFT; // page index 49 int pages = len >> PAGE_SHIFT; 50 u_long *p; 51 u_long *max; 52 53 while (pages) { 54 page = page_read(mapping, index); 55 if (!page) 56 return -ENOMEM; 57 if (IS_ERR(page)) 58 return PTR_ERR(page); 59 60 max = page_address(page) + PAGE_SIZE; 61 for (p=page_address(page); p<max; p++) 62 if (*p != -1UL) { 63 lock_page(page); 64 memset(page_address(page), 0xff, PAGE_SIZE); 65 set_page_dirty(page); 66 unlock_page(page); 67 break; 68 } 69 70 page_cache_release(page); 71 pages--; 72 index++; 73 } 74 return 0; 75 } 76 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr) 77 { 78 struct block2mtd_dev *dev = mtd->priv; 79 size_t from = instr->addr; 80 size_t len = instr->len; 81 int err; 82 83 instr->state = MTD_ERASING; 84 mutex_lock(&dev->write_mutex); 85 err = _block2mtd_erase(dev, from, len); 86 mutex_unlock(&dev->write_mutex); 87 if (err) { 88 ERROR("erase failed err = %d", err); 89 instr->state = MTD_ERASE_FAILED; 90 } else 91 instr->state = MTD_ERASE_DONE; 92 93 mtd_erase_callback(instr); 94 return err; 95 } 96 97 98 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len, 99 size_t *retlen, u_char *buf) 100 { 101 struct block2mtd_dev *dev = mtd->priv; 102 struct page *page; 103 int index = from >> PAGE_SHIFT; 104 int offset = from & (PAGE_SIZE-1); 105 int cpylen; 106 107 while (len) { 108 if ((offset + len) > PAGE_SIZE) 109 cpylen = PAGE_SIZE - offset; // multiple pages 110 else 111 cpylen = len; // this page 112 len = len - cpylen; 113 114 page = page_read(dev->blkdev->bd_inode->i_mapping, index); 115 if (!page) 116 return -ENOMEM; 117 if (IS_ERR(page)) 118 return PTR_ERR(page); 119 120 memcpy(buf, page_address(page) + offset, cpylen); 121 page_cache_release(page); 122 123 if (retlen) 124 *retlen += cpylen; 125 buf += cpylen; 126 offset = 0; 127 index++; 128 } 129 return 0; 130 } 131 132 133 /* write data to the underlying device */ 134 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf, 135 loff_t to, size_t len, size_t *retlen) 136 { 137 struct page *page; 138 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping; 139 int index = to >> PAGE_SHIFT; // page index 140 int offset = to & ~PAGE_MASK; // page offset 141 int cpylen; 142 143 while (len) { 144 if ((offset+len) > PAGE_SIZE) 145 cpylen = PAGE_SIZE - offset; // multiple pages 146 else 147 cpylen = len; // this page 148 len = len - cpylen; 149 150 page = page_read(mapping, index); 151 if (!page) 152 return -ENOMEM; 153 if (IS_ERR(page)) 154 return PTR_ERR(page); 155 156 if (memcmp(page_address(page)+offset, buf, cpylen)) { 157 lock_page(page); 158 memcpy(page_address(page) + offset, buf, cpylen); 159 set_page_dirty(page); 160 unlock_page(page); 161 } 162 page_cache_release(page); 163 164 if (retlen) 165 *retlen += cpylen; 166 167 buf += cpylen; 168 offset = 0; 169 index++; 170 } 171 return 0; 172 } 173 174 175 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len, 176 size_t *retlen, const u_char *buf) 177 { 178 struct block2mtd_dev *dev = mtd->priv; 179 int err; 180 181 mutex_lock(&dev->write_mutex); 182 err = _block2mtd_write(dev, buf, to, len, retlen); 183 mutex_unlock(&dev->write_mutex); 184 if (err > 0) 185 err = 0; 186 return err; 187 } 188 189 190 /* sync the device - wait until the write queue is empty */ 191 static void block2mtd_sync(struct mtd_info *mtd) 192 { 193 struct block2mtd_dev *dev = mtd->priv; 194 sync_blockdev(dev->blkdev); 195 return; 196 } 197 198 199 static void block2mtd_free_device(struct block2mtd_dev *dev) 200 { 201 if (!dev) 202 return; 203 204 kfree(dev->mtd.name); 205 206 if (dev->blkdev) { 207 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping, 208 0, -1); 209 blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); 210 } 211 212 kfree(dev); 213 } 214 215 216 /* FIXME: ensure that mtd->size % erase_size == 0 */ 217 static struct block2mtd_dev *add_device(char *devname, int erase_size) 218 { 219 const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL; 220 struct block_device *bdev; 221 struct block2mtd_dev *dev; 222 char *name; 223 224 if (!devname) 225 return NULL; 226 227 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL); 228 if (!dev) 229 return NULL; 230 231 /* Get a handle on the device */ 232 bdev = blkdev_get_by_path(devname, mode, dev); 233 #ifndef MODULE 234 if (IS_ERR(bdev)) { 235 236 /* We might not have rootfs mounted at this point. Try 237 to resolve the device name by other means. */ 238 239 dev_t devt = name_to_dev_t(devname); 240 if (devt) 241 bdev = blkdev_get_by_dev(devt, mode, dev); 242 } 243 #endif 244 245 if (IS_ERR(bdev)) { 246 ERROR("error: cannot open device %s", devname); 247 goto devinit_err; 248 } 249 dev->blkdev = bdev; 250 251 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) { 252 ERROR("attempting to use an MTD device as a block device"); 253 goto devinit_err; 254 } 255 256 mutex_init(&dev->write_mutex); 257 258 /* Setup the MTD structure */ 259 /* make the name contain the block device in */ 260 name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname); 261 if (!name) 262 goto devinit_err; 263 264 dev->mtd.name = name; 265 266 dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK; 267 dev->mtd.erasesize = erase_size; 268 dev->mtd.writesize = 1; 269 dev->mtd.writebufsize = PAGE_SIZE; 270 dev->mtd.type = MTD_RAM; 271 dev->mtd.flags = MTD_CAP_RAM; 272 dev->mtd._erase = block2mtd_erase; 273 dev->mtd._write = block2mtd_write; 274 dev->mtd._writev = mtd_writev; 275 dev->mtd._sync = block2mtd_sync; 276 dev->mtd._read = block2mtd_read; 277 dev->mtd.priv = dev; 278 dev->mtd.owner = THIS_MODULE; 279 280 if (mtd_device_register(&dev->mtd, NULL, 0)) { 281 /* Device didn't get added, so free the entry */ 282 goto devinit_err; 283 } 284 list_add(&dev->list, &blkmtd_device_list); 285 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index, 286 dev->mtd.name + strlen("block2mtd: "), 287 dev->mtd.erasesize >> 10, dev->mtd.erasesize); 288 return dev; 289 290 devinit_err: 291 block2mtd_free_device(dev); 292 return NULL; 293 } 294 295 296 /* This function works similar to reguler strtoul. In addition, it 297 * allows some suffixes for a more human-readable number format: 298 * ki, Ki, kiB, KiB - multiply result with 1024 299 * Mi, MiB - multiply result with 1024^2 300 * Gi, GiB - multiply result with 1024^3 301 */ 302 static int ustrtoul(const char *cp, char **endp, unsigned int base) 303 { 304 unsigned long result = simple_strtoul(cp, endp, base); 305 switch (**endp) { 306 case 'G' : 307 result *= 1024; 308 case 'M': 309 result *= 1024; 310 case 'K': 311 case 'k': 312 result *= 1024; 313 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */ 314 if ((*endp)[1] == 'i') { 315 if ((*endp)[2] == 'B') 316 (*endp) += 3; 317 else 318 (*endp) += 2; 319 } 320 } 321 return result; 322 } 323 324 325 static int parse_num(size_t *num, const char *token) 326 { 327 char *endp; 328 size_t n; 329 330 n = (size_t) ustrtoul(token, &endp, 0); 331 if (*endp) 332 return -EINVAL; 333 334 *num = n; 335 return 0; 336 } 337 338 339 static inline void kill_final_newline(char *str) 340 { 341 char *newline = strrchr(str, '\n'); 342 if (newline && !newline[1]) 343 *newline = 0; 344 } 345 346 347 #define parse_err(fmt, args...) do { \ 348 ERROR(fmt, ## args); \ 349 return 0; \ 350 } while (0) 351 352 #ifndef MODULE 353 static int block2mtd_init_called = 0; 354 static char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */ 355 #endif 356 357 358 static int block2mtd_setup2(const char *val) 359 { 360 char buf[80 + 12]; /* 80 for device, 12 for erase size */ 361 char *str = buf; 362 char *token[2]; 363 char *name; 364 size_t erase_size = PAGE_SIZE; 365 int i, ret; 366 367 if (strnlen(val, sizeof(buf)) >= sizeof(buf)) 368 parse_err("parameter too long"); 369 370 strcpy(str, val); 371 kill_final_newline(str); 372 373 for (i = 0; i < 2; i++) 374 token[i] = strsep(&str, ","); 375 376 if (str) 377 parse_err("too many arguments"); 378 379 if (!token[0]) 380 parse_err("no argument"); 381 382 name = token[0]; 383 if (strlen(name) + 1 > 80) 384 parse_err("device name too long"); 385 386 if (token[1]) { 387 ret = parse_num(&erase_size, token[1]); 388 if (ret) { 389 parse_err("illegal erase size"); 390 } 391 } 392 393 add_device(name, erase_size); 394 395 return 0; 396 } 397 398 399 static int block2mtd_setup(const char *val, struct kernel_param *kp) 400 { 401 #ifdef MODULE 402 return block2mtd_setup2(val); 403 #else 404 /* If more parameters are later passed in via 405 /sys/module/block2mtd/parameters/block2mtd 406 and block2mtd_init() has already been called, 407 we can parse the argument now. */ 408 409 if (block2mtd_init_called) 410 return block2mtd_setup2(val); 411 412 /* During early boot stage, we only save the parameters 413 here. We must parse them later: if the param passed 414 from kernel boot command line, block2mtd_setup() is 415 called so early that it is not possible to resolve 416 the device (even kmalloc() fails). Deter that work to 417 block2mtd_setup2(). */ 418 419 strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline)); 420 421 return 0; 422 #endif 423 } 424 425 426 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200); 427 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\""); 428 429 static int __init block2mtd_init(void) 430 { 431 int ret = 0; 432 433 #ifndef MODULE 434 if (strlen(block2mtd_paramline)) 435 ret = block2mtd_setup2(block2mtd_paramline); 436 block2mtd_init_called = 1; 437 #endif 438 439 return ret; 440 } 441 442 443 static void __devexit block2mtd_exit(void) 444 { 445 struct list_head *pos, *next; 446 447 /* Remove the MTD devices */ 448 list_for_each_safe(pos, next, &blkmtd_device_list) { 449 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list); 450 block2mtd_sync(&dev->mtd); 451 mtd_device_unregister(&dev->mtd); 452 INFO("mtd%d: [%s] removed", dev->mtd.index, 453 dev->mtd.name + strlen("block2mtd: ")); 454 list_del(&dev->list); 455 block2mtd_free_device(dev); 456 } 457 } 458 459 460 module_init(block2mtd_init); 461 module_exit(block2mtd_exit); 462 463 MODULE_LICENSE("GPL"); 464 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>"); 465 MODULE_DESCRIPTION("Emulate an MTD using a block device"); 466