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/buffer_head.h> 18 #include <linux/mutex.h> 19 #include <linux/mount.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 instr->state = MTD_ERASE_DONE; 94 mtd_erase_callback(instr); 95 return err; 96 } 97 98 99 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len, 100 size_t *retlen, u_char *buf) 101 { 102 struct block2mtd_dev *dev = mtd->priv; 103 struct page *page; 104 int index = from >> PAGE_SHIFT; 105 int offset = from & (PAGE_SIZE-1); 106 int cpylen; 107 108 if (from > mtd->size) 109 return -EINVAL; 110 if (from + len > mtd->size) 111 len = mtd->size - from; 112 113 if (retlen) 114 *retlen = 0; 115 116 while (len) { 117 if ((offset + len) > PAGE_SIZE) 118 cpylen = PAGE_SIZE - offset; // multiple pages 119 else 120 cpylen = len; // this page 121 len = len - cpylen; 122 123 page = page_read(dev->blkdev->bd_inode->i_mapping, index); 124 if (!page) 125 return -ENOMEM; 126 if (IS_ERR(page)) 127 return PTR_ERR(page); 128 129 memcpy(buf, page_address(page) + offset, cpylen); 130 page_cache_release(page); 131 132 if (retlen) 133 *retlen += cpylen; 134 buf += cpylen; 135 offset = 0; 136 index++; 137 } 138 return 0; 139 } 140 141 142 /* write data to the underlying device */ 143 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf, 144 loff_t to, size_t len, size_t *retlen) 145 { 146 struct page *page; 147 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping; 148 int index = to >> PAGE_SHIFT; // page index 149 int offset = to & ~PAGE_MASK; // page offset 150 int cpylen; 151 152 if (retlen) 153 *retlen = 0; 154 while (len) { 155 if ((offset+len) > PAGE_SIZE) 156 cpylen = PAGE_SIZE - offset; // multiple pages 157 else 158 cpylen = len; // this page 159 len = len - cpylen; 160 161 page = page_read(mapping, index); 162 if (!page) 163 return -ENOMEM; 164 if (IS_ERR(page)) 165 return PTR_ERR(page); 166 167 if (memcmp(page_address(page)+offset, buf, cpylen)) { 168 lock_page(page); 169 memcpy(page_address(page) + offset, buf, cpylen); 170 set_page_dirty(page); 171 unlock_page(page); 172 } 173 page_cache_release(page); 174 175 if (retlen) 176 *retlen += cpylen; 177 178 buf += cpylen; 179 offset = 0; 180 index++; 181 } 182 return 0; 183 } 184 185 186 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len, 187 size_t *retlen, const u_char *buf) 188 { 189 struct block2mtd_dev *dev = mtd->priv; 190 int err; 191 192 if (!len) 193 return 0; 194 if (to >= mtd->size) 195 return -ENOSPC; 196 if (to + len > mtd->size) 197 len = mtd->size - to; 198 199 mutex_lock(&dev->write_mutex); 200 err = _block2mtd_write(dev, buf, to, len, retlen); 201 mutex_unlock(&dev->write_mutex); 202 if (err > 0) 203 err = 0; 204 return err; 205 } 206 207 208 /* sync the device - wait until the write queue is empty */ 209 static void block2mtd_sync(struct mtd_info *mtd) 210 { 211 struct block2mtd_dev *dev = mtd->priv; 212 sync_blockdev(dev->blkdev); 213 return; 214 } 215 216 217 static void block2mtd_free_device(struct block2mtd_dev *dev) 218 { 219 if (!dev) 220 return; 221 222 kfree(dev->mtd.name); 223 224 if (dev->blkdev) { 225 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping, 226 0, -1); 227 close_bdev_exclusive(dev->blkdev, FMODE_READ|FMODE_WRITE); 228 } 229 230 kfree(dev); 231 } 232 233 234 /* FIXME: ensure that mtd->size % erase_size == 0 */ 235 static struct block2mtd_dev *add_device(char *devname, int erase_size) 236 { 237 struct block_device *bdev; 238 struct block2mtd_dev *dev; 239 char *name; 240 241 if (!devname) 242 return NULL; 243 244 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL); 245 if (!dev) 246 return NULL; 247 248 /* Get a handle on the device */ 249 bdev = open_bdev_exclusive(devname, FMODE_READ|FMODE_WRITE, NULL); 250 #ifndef MODULE 251 if (IS_ERR(bdev)) { 252 253 /* We might not have rootfs mounted at this point. Try 254 to resolve the device name by other means. */ 255 256 dev_t devt = name_to_dev_t(devname); 257 if (devt) { 258 bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ); 259 } 260 } 261 #endif 262 263 if (IS_ERR(bdev)) { 264 ERROR("error: cannot open device %s", devname); 265 goto devinit_err; 266 } 267 dev->blkdev = bdev; 268 269 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) { 270 ERROR("attempting to use an MTD device as a block device"); 271 goto devinit_err; 272 } 273 274 mutex_init(&dev->write_mutex); 275 276 /* Setup the MTD structure */ 277 /* make the name contain the block device in */ 278 name = kmalloc(sizeof("block2mtd: ") + strlen(devname) + 1, 279 GFP_KERNEL); 280 if (!name) 281 goto devinit_err; 282 283 sprintf(name, "block2mtd: %s", devname); 284 dev->mtd.name = name; 285 286 dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK; 287 dev->mtd.erasesize = erase_size; 288 dev->mtd.writesize = 1; 289 dev->mtd.type = MTD_RAM; 290 dev->mtd.flags = MTD_CAP_RAM; 291 dev->mtd.erase = block2mtd_erase; 292 dev->mtd.write = block2mtd_write; 293 dev->mtd.writev = default_mtd_writev; 294 dev->mtd.sync = block2mtd_sync; 295 dev->mtd.read = block2mtd_read; 296 dev->mtd.priv = dev; 297 dev->mtd.owner = THIS_MODULE; 298 299 if (add_mtd_device(&dev->mtd)) { 300 /* Device didnt get added, so free the entry */ 301 goto devinit_err; 302 } 303 list_add(&dev->list, &blkmtd_device_list); 304 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index, 305 dev->mtd.name + strlen("block2mtd: "), 306 dev->mtd.erasesize >> 10, dev->mtd.erasesize); 307 return dev; 308 309 devinit_err: 310 block2mtd_free_device(dev); 311 return NULL; 312 } 313 314 315 /* This function works similar to reguler strtoul. In addition, it 316 * allows some suffixes for a more human-readable number format: 317 * ki, Ki, kiB, KiB - multiply result with 1024 318 * Mi, MiB - multiply result with 1024^2 319 * Gi, GiB - multiply result with 1024^3 320 */ 321 static int ustrtoul(const char *cp, char **endp, unsigned int base) 322 { 323 unsigned long result = simple_strtoul(cp, endp, base); 324 switch (**endp) { 325 case 'G' : 326 result *= 1024; 327 case 'M': 328 result *= 1024; 329 case 'K': 330 case 'k': 331 result *= 1024; 332 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */ 333 if ((*endp)[1] == 'i') { 334 if ((*endp)[2] == 'B') 335 (*endp) += 3; 336 else 337 (*endp) += 2; 338 } 339 } 340 return result; 341 } 342 343 344 static int parse_num(size_t *num, const char *token) 345 { 346 char *endp; 347 size_t n; 348 349 n = (size_t) ustrtoul(token, &endp, 0); 350 if (*endp) 351 return -EINVAL; 352 353 *num = n; 354 return 0; 355 } 356 357 358 static inline void kill_final_newline(char *str) 359 { 360 char *newline = strrchr(str, '\n'); 361 if (newline && !newline[1]) 362 *newline = 0; 363 } 364 365 366 #define parse_err(fmt, args...) do { \ 367 ERROR(fmt, ## args); \ 368 return 0; \ 369 } while (0) 370 371 #ifndef MODULE 372 static int block2mtd_init_called = 0; 373 static char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */ 374 #endif 375 376 377 static int block2mtd_setup2(const char *val) 378 { 379 char buf[80 + 12]; /* 80 for device, 12 for erase size */ 380 char *str = buf; 381 char *token[2]; 382 char *name; 383 size_t erase_size = PAGE_SIZE; 384 int i, ret; 385 386 if (strnlen(val, sizeof(buf)) >= sizeof(buf)) 387 parse_err("parameter too long"); 388 389 strcpy(str, val); 390 kill_final_newline(str); 391 392 for (i = 0; i < 2; i++) 393 token[i] = strsep(&str, ","); 394 395 if (str) 396 parse_err("too many arguments"); 397 398 if (!token[0]) 399 parse_err("no argument"); 400 401 name = token[0]; 402 if (strlen(name) + 1 > 80) 403 parse_err("device name too long"); 404 405 if (token[1]) { 406 ret = parse_num(&erase_size, token[1]); 407 if (ret) { 408 parse_err("illegal erase size"); 409 } 410 } 411 412 add_device(name, erase_size); 413 414 return 0; 415 } 416 417 418 static int block2mtd_setup(const char *val, struct kernel_param *kp) 419 { 420 #ifdef MODULE 421 return block2mtd_setup2(val); 422 #else 423 /* If more parameters are later passed in via 424 /sys/module/block2mtd/parameters/block2mtd 425 and block2mtd_init() has already been called, 426 we can parse the argument now. */ 427 428 if (block2mtd_init_called) 429 return block2mtd_setup2(val); 430 431 /* During early boot stage, we only save the parameters 432 here. We must parse them later: if the param passed 433 from kernel boot command line, block2mtd_setup() is 434 called so early that it is not possible to resolve 435 the device (even kmalloc() fails). Deter that work to 436 block2mtd_setup2(). */ 437 438 strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline)); 439 440 return 0; 441 #endif 442 } 443 444 445 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200); 446 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\""); 447 448 static int __init block2mtd_init(void) 449 { 450 int ret = 0; 451 452 #ifndef MODULE 453 if (strlen(block2mtd_paramline)) 454 ret = block2mtd_setup2(block2mtd_paramline); 455 block2mtd_init_called = 1; 456 #endif 457 458 return ret; 459 } 460 461 462 static void __devexit block2mtd_exit(void) 463 { 464 struct list_head *pos, *next; 465 466 /* Remove the MTD devices */ 467 list_for_each_safe(pos, next, &blkmtd_device_list) { 468 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list); 469 block2mtd_sync(&dev->mtd); 470 del_mtd_device(&dev->mtd); 471 INFO("mtd%d: [%s] removed", dev->mtd.index, 472 dev->mtd.name + strlen("block2mtd: ")); 473 list_del(&dev->list); 474 block2mtd_free_device(dev); 475 } 476 } 477 478 479 module_init(block2mtd_init); 480 module_exit(block2mtd_exit); 481 482 MODULE_LICENSE("GPL"); 483 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>"); 484 MODULE_DESCRIPTION("Emulate an MTD using a block device"); 485