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 #include <linux/slab.h> 21 22 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args) 23 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args) 24 25 26 /* Info for the block device */ 27 struct block2mtd_dev { 28 struct list_head list; 29 struct block_device *blkdev; 30 struct mtd_info mtd; 31 struct mutex write_mutex; 32 }; 33 34 35 /* Static info about the MTD, used in cleanup_module */ 36 static LIST_HEAD(blkmtd_device_list); 37 38 39 static struct page *page_read(struct address_space *mapping, int index) 40 { 41 return read_mapping_page(mapping, index, NULL); 42 } 43 44 /* erase a specified part of the device */ 45 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len) 46 { 47 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping; 48 struct page *page; 49 int index = to >> PAGE_SHIFT; // page index 50 int pages = len >> PAGE_SHIFT; 51 u_long *p; 52 u_long *max; 53 54 while (pages) { 55 page = page_read(mapping, index); 56 if (!page) 57 return -ENOMEM; 58 if (IS_ERR(page)) 59 return PTR_ERR(page); 60 61 max = page_address(page) + PAGE_SIZE; 62 for (p=page_address(page); p<max; p++) 63 if (*p != -1UL) { 64 lock_page(page); 65 memset(page_address(page), 0xff, PAGE_SIZE); 66 set_page_dirty(page); 67 unlock_page(page); 68 break; 69 } 70 71 page_cache_release(page); 72 pages--; 73 index++; 74 } 75 return 0; 76 } 77 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr) 78 { 79 struct block2mtd_dev *dev = mtd->priv; 80 size_t from = instr->addr; 81 size_t len = instr->len; 82 int err; 83 84 instr->state = MTD_ERASING; 85 mutex_lock(&dev->write_mutex); 86 err = _block2mtd_erase(dev, from, len); 87 mutex_unlock(&dev->write_mutex); 88 if (err) { 89 ERROR("erase failed err = %d", err); 90 instr->state = MTD_ERASE_FAILED; 91 } else 92 instr->state = MTD_ERASE_DONE; 93 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 blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); 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 const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL; 238 struct block_device *bdev; 239 struct block2mtd_dev *dev; 240 char *name; 241 242 if (!devname) 243 return NULL; 244 245 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL); 246 if (!dev) 247 return NULL; 248 249 /* Get a handle on the device */ 250 bdev = blkdev_get_by_path(devname, mode, dev); 251 #ifndef MODULE 252 if (IS_ERR(bdev)) { 253 254 /* We might not have rootfs mounted at this point. Try 255 to resolve the device name by other means. */ 256 257 dev_t devt = name_to_dev_t(devname); 258 if (devt) 259 bdev = blkdev_get_by_dev(devt, mode, dev); 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 = kasprintf(GFP_KERNEL, "block2mtd: %s", devname); 279 if (!name) 280 goto devinit_err; 281 282 dev->mtd.name = name; 283 284 dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK; 285 dev->mtd.erasesize = erase_size; 286 dev->mtd.writesize = 1; 287 dev->mtd.type = MTD_RAM; 288 dev->mtd.flags = MTD_CAP_RAM; 289 dev->mtd.erase = block2mtd_erase; 290 dev->mtd.write = block2mtd_write; 291 dev->mtd.writev = default_mtd_writev; 292 dev->mtd.sync = block2mtd_sync; 293 dev->mtd.read = block2mtd_read; 294 dev->mtd.priv = dev; 295 dev->mtd.owner = THIS_MODULE; 296 297 if (add_mtd_device(&dev->mtd)) { 298 /* Device didnt get added, so free the entry */ 299 goto devinit_err; 300 } 301 list_add(&dev->list, &blkmtd_device_list); 302 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index, 303 dev->mtd.name + strlen("block2mtd: "), 304 dev->mtd.erasesize >> 10, dev->mtd.erasesize); 305 return dev; 306 307 devinit_err: 308 block2mtd_free_device(dev); 309 return NULL; 310 } 311 312 313 /* This function works similar to reguler strtoul. In addition, it 314 * allows some suffixes for a more human-readable number format: 315 * ki, Ki, kiB, KiB - multiply result with 1024 316 * Mi, MiB - multiply result with 1024^2 317 * Gi, GiB - multiply result with 1024^3 318 */ 319 static int ustrtoul(const char *cp, char **endp, unsigned int base) 320 { 321 unsigned long result = simple_strtoul(cp, endp, base); 322 switch (**endp) { 323 case 'G' : 324 result *= 1024; 325 case 'M': 326 result *= 1024; 327 case 'K': 328 case 'k': 329 result *= 1024; 330 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */ 331 if ((*endp)[1] == 'i') { 332 if ((*endp)[2] == 'B') 333 (*endp) += 3; 334 else 335 (*endp) += 2; 336 } 337 } 338 return result; 339 } 340 341 342 static int parse_num(size_t *num, const char *token) 343 { 344 char *endp; 345 size_t n; 346 347 n = (size_t) ustrtoul(token, &endp, 0); 348 if (*endp) 349 return -EINVAL; 350 351 *num = n; 352 return 0; 353 } 354 355 356 static inline void kill_final_newline(char *str) 357 { 358 char *newline = strrchr(str, '\n'); 359 if (newline && !newline[1]) 360 *newline = 0; 361 } 362 363 364 #define parse_err(fmt, args...) do { \ 365 ERROR(fmt, ## args); \ 366 return 0; \ 367 } while (0) 368 369 #ifndef MODULE 370 static int block2mtd_init_called = 0; 371 static char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */ 372 #endif 373 374 375 static int block2mtd_setup2(const char *val) 376 { 377 char buf[80 + 12]; /* 80 for device, 12 for erase size */ 378 char *str = buf; 379 char *token[2]; 380 char *name; 381 size_t erase_size = PAGE_SIZE; 382 int i, ret; 383 384 if (strnlen(val, sizeof(buf)) >= sizeof(buf)) 385 parse_err("parameter too long"); 386 387 strcpy(str, val); 388 kill_final_newline(str); 389 390 for (i = 0; i < 2; i++) 391 token[i] = strsep(&str, ","); 392 393 if (str) 394 parse_err("too many arguments"); 395 396 if (!token[0]) 397 parse_err("no argument"); 398 399 name = token[0]; 400 if (strlen(name) + 1 > 80) 401 parse_err("device name too long"); 402 403 if (token[1]) { 404 ret = parse_num(&erase_size, token[1]); 405 if (ret) { 406 parse_err("illegal erase size"); 407 } 408 } 409 410 add_device(name, erase_size); 411 412 return 0; 413 } 414 415 416 static int block2mtd_setup(const char *val, struct kernel_param *kp) 417 { 418 #ifdef MODULE 419 return block2mtd_setup2(val); 420 #else 421 /* If more parameters are later passed in via 422 /sys/module/block2mtd/parameters/block2mtd 423 and block2mtd_init() has already been called, 424 we can parse the argument now. */ 425 426 if (block2mtd_init_called) 427 return block2mtd_setup2(val); 428 429 /* During early boot stage, we only save the parameters 430 here. We must parse them later: if the param passed 431 from kernel boot command line, block2mtd_setup() is 432 called so early that it is not possible to resolve 433 the device (even kmalloc() fails). Deter that work to 434 block2mtd_setup2(). */ 435 436 strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline)); 437 438 return 0; 439 #endif 440 } 441 442 443 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200); 444 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\""); 445 446 static int __init block2mtd_init(void) 447 { 448 int ret = 0; 449 450 #ifndef MODULE 451 if (strlen(block2mtd_paramline)) 452 ret = block2mtd_setup2(block2mtd_paramline); 453 block2mtd_init_called = 1; 454 #endif 455 456 return ret; 457 } 458 459 460 static void __devexit block2mtd_exit(void) 461 { 462 struct list_head *pos, *next; 463 464 /* Remove the MTD devices */ 465 list_for_each_safe(pos, next, &blkmtd_device_list) { 466 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list); 467 block2mtd_sync(&dev->mtd); 468 del_mtd_device(&dev->mtd); 469 INFO("mtd%d: [%s] removed", dev->mtd.index, 470 dev->mtd.name + strlen("block2mtd: ")); 471 list_del(&dev->list); 472 block2mtd_free_device(dev); 473 } 474 } 475 476 477 module_init(block2mtd_init); 478 module_exit(block2mtd_exit); 479 480 MODULE_LICENSE("GPL"); 481 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>"); 482 MODULE_DESCRIPTION("Emulate an MTD using a block device"); 483