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