drivers/mtd/devices/block2mtd.c

   1 /*
   2  * $Id: block2mtd.c,v 1.30 2005/11/29 14:48:32 gleixner Exp $
   3  *
   4  * block2mtd.c - create an mtd from a block device
   5  *
   6  * Copyright (C) 2001,2002      Simon Evans <spse@secret.org.uk>
   7  * Copyright (C) 2004-2006      Jörn Engel <joern@wh.fh-wedel.de>
   8  *
   9  * Licence: GPL
  10  */
  11 #include <linux/module.h>
  12 #include <linux/fs.h>
  13 #include <linux/blkdev.h>
  14 #include <linux/bio.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/list.h>
  17 #include <linux/init.h>
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/buffer_head.h>
  20 #include <linux/mutex.h>
  21 #include <linux/mount.h>
  22
  23 #define VERSION "$Revision: 1.30 $"
  24
  25
  26 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
  27 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
  28
  29
  30 /* Info for the block device */
  31 struct block2mtd_dev {
  32         struct list_head list;
  33         struct block_device *blkdev;
  34         struct mtd_info mtd;
  35         struct mutex write_mutex;
  36 };
  37
  38
  39 /* Static info about the MTD, used in cleanup_module */
  40 static LIST_HEAD(blkmtd_device_list);
  41
  42
  43 #define PAGE_READAHEAD 64
  44 static void cache_readahead(struct address_space *mapping, int index)
  45 {
  46         filler_t *filler = (filler_t*)mapping->a_ops->readpage;
  47         int i, pagei;
  48         unsigned ret = 0;
  49         unsigned long end_index;
  50         struct page *page;
  51         LIST_HEAD(page_pool);
  52         struct inode *inode = mapping->host;
  53         loff_t isize = i_size_read(inode);
  54
  55         if (!isize) {
  56                 INFO("iSize=0 in cache_readahead\n");
  57                 return;
  58         }
  59
  60         end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);
  61
  62         read_lock_irq(&mapping->tree_lock);
  63         for (i = 0; i < PAGE_READAHEAD; i++) {
  64                 pagei = index + i;
  65                 if (pagei > end_index) {
  66                         INFO("Overrun end of disk in cache readahead\n");
  67                         break;
  68                 }
  69                 page = radix_tree_lookup(&mapping->page_tree, pagei);
  70                 if (page && (!i))
  71                         break;
  72                 if (page)
  73                         continue;
  74                 read_unlock_irq(&mapping->tree_lock);
  75                 page = page_cache_alloc_cold(mapping);
  76                 read_lock_irq(&mapping->tree_lock);
  77                 if (!page)
  78                         break;
  79                 page->index = pagei;
  80                 list_add(&page->lru, &page_pool);
  81                 ret++;
  82         }
  83         read_unlock_irq(&mapping->tree_lock);
  84         if (ret)
  85                 read_cache_pages(mapping, &page_pool, filler, NULL);
  86 }
  87
  88
  89 static struct page* page_readahead(struct address_space *mapping, int index)
  90 {
  91         filler_t *filler = (filler_t*)mapping->a_ops->readpage;
  92         cache_readahead(mapping, index);
  93         return read_cache_page(mapping, index, filler, NULL);
  94 }
  95
  96
  97 /* erase a specified part of the device */
  98 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
  99 {
 100         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
 101         struct page *page;
 102         int index = to >> PAGE_SHIFT;   // page index
 103         int pages = len >> PAGE_SHIFT;
 104         u_long *p;
 105         u_long *max;
 106
 107         while (pages) {
 108                 page = page_readahead(mapping, index);
 109                 if (!page)
 110                         return -ENOMEM;
 111                 if (IS_ERR(page))
 112                         return PTR_ERR(page);
 113
 114                 max = (u_long*)page_address(page) + PAGE_SIZE;
 115                 for (p=(u_long*)page_address(page); p<max; p++)
 116                         if (*p != -1UL) {
 117                                 lock_page(page);
 118                                 memset(page_address(page), 0xff, PAGE_SIZE);
 119                                 set_page_dirty(page);
 120                                 unlock_page(page);
 121                                 break;
 122                         }
 123
 124                 page_cache_release(page);
 125                 pages--;
 126                 index++;
 127         }
 128         return 0;
 129 }
 130 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
 131 {
 132         struct block2mtd_dev *dev = mtd->priv;
 133         size_t from = instr->addr;
 134         size_t len = instr->len;
 135         int err;
 136
 137         instr->state = MTD_ERASING;
 138         mutex_lock(&dev->write_mutex);
 139         err = _block2mtd_erase(dev, from, len);
 140         mutex_unlock(&dev->write_mutex);
 141         if (err) {
 142                 ERROR("erase failed err = %d", err);
 143                 instr->state = MTD_ERASE_FAILED;
 144         } else
 145                 instr->state = MTD_ERASE_DONE;
 146
 147         instr->state = MTD_ERASE_DONE;
 148         mtd_erase_callback(instr);
 149         return err;
 150 }
 151
 152
 153 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
 154                 size_t *retlen, u_char *buf)
 155 {
 156         struct block2mtd_dev *dev = mtd->priv;
 157         struct page *page;
 158         int index = from >> PAGE_SHIFT;
 159         int offset = from & (PAGE_SIZE-1);
 160         int cpylen;
 161
 162         if (from > mtd->size)
 163                 return -EINVAL;
 164         if (from + len > mtd->size)
 165                 len = mtd->size - from;
 166
 167         if (retlen)
 168                 *retlen = 0;
 169
 170         while (len) {
 171                 if ((offset + len) > PAGE_SIZE)
 172                         cpylen = PAGE_SIZE - offset;    // multiple pages
 173                 else
 174                         cpylen = len;   // this page
 175                 len = len - cpylen;
 176
 177                 //      Get page
 178                 page = page_readahead(dev->blkdev->bd_inode->i_mapping, index);
 179                 if (!page)
 180                         return -ENOMEM;
 181                 if (IS_ERR(page))
 182                         return PTR_ERR(page);
 183
 184                 memcpy(buf, page_address(page) + offset, cpylen);
 185                 page_cache_release(page);
 186
 187                 if (retlen)
 188                         *retlen += cpylen;
 189                 buf += cpylen;
 190                 offset = 0;
 191                 index++;
 192         }
 193         return 0;
 194 }
 195
 196
 197 /* write data to the underlying device */
 198 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
 199                 loff_t to, size_t len, size_t *retlen)
 200 {
 201         struct page *page;
 202         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
 203         int index = to >> PAGE_SHIFT;   // page index
 204         int offset = to & ~PAGE_MASK;   // page offset
 205         int cpylen;
 206
 207         if (retlen)
 208                 *retlen = 0;
 209         while (len) {
 210                 if ((offset+len) > PAGE_SIZE)
 211                         cpylen = PAGE_SIZE - offset;    // multiple pages
 212                 else
 213                         cpylen = len;                   // this page
 214                 len = len - cpylen;
 215
 216                 //      Get page
 217                 page = page_readahead(mapping, index);
 218                 if (!page)
 219                         return -ENOMEM;
 220                 if (IS_ERR(page))
 221                         return PTR_ERR(page);
 222
 223                 if (memcmp(page_address(page)+offset, buf, cpylen)) {
 224                         lock_page(page);
 225                         memcpy(page_address(page) + offset, buf, cpylen);
 226                         set_page_dirty(page);
 227                         unlock_page(page);
 228                 }
 229                 page_cache_release(page);
 230
 231                 if (retlen)
 232                         *retlen += cpylen;
 233
 234                 buf += cpylen;
 235                 offset = 0;
 236                 index++;
 237         }
 238         return 0;
 239 }
 240
 241
 242 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
 243                 size_t *retlen, const u_char *buf)
 244 {
 245         struct block2mtd_dev *dev = mtd->priv;
 246         int err;
 247
 248         if (!len)
 249                 return 0;
 250         if (to >= mtd->size)
 251                 return -ENOSPC;
 252         if (to + len > mtd->size)
 253                 len = mtd->size - to;
 254
 255         mutex_lock(&dev->write_mutex);
 256         err = _block2mtd_write(dev, buf, to, len, retlen);
 257         mutex_unlock(&dev->write_mutex);
 258         if (err > 0)
 259                 err = 0;
 260         return err;
 261 }
 262
 263
 264 /* sync the device - wait until the write queue is empty */
 265 static void block2mtd_sync(struct mtd_info *mtd)
 266 {
 267         struct block2mtd_dev *dev = mtd->priv;
 268         sync_blockdev(dev->blkdev);
 269         return;
 270 }
 271
 272
 273 static void block2mtd_free_device(struct block2mtd_dev *dev)
 274 {
 275         if (!dev)
 276                 return;
 277
 278         kfree(dev->mtd.name);
 279
 280         if (dev->blkdev) {
 281                 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
 282                                         0, -1);
 283                 close_bdev_excl(dev->blkdev);
 284         }
 285
 286         kfree(dev);
 287 }
 288
 289
 290 /* FIXME: ensure that mtd->size % erase_size == 0 */
 291 static struct block2mtd_dev *add_device(char *devname, int erase_size)
 292 {
 293         struct block_device *bdev;
 294         struct block2mtd_dev *dev;
 295
 296         if (!devname)
 297                 return NULL;
 298
 299         dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
 300         if (!dev)
 301                 return NULL;
 302
 303         /* Get a handle on the device */
 304         bdev = open_bdev_excl(devname, O_RDWR, NULL);
 305 #ifndef MODULE
 306         if (IS_ERR(bdev)) {
 307
 308                 /* We might not have rootfs mounted at this point. Try
 309                    to resolve the device name by other means. */
 310
 311                 dev_t dev = name_to_dev_t(devname);
 312                 if (dev != 0) {
 313                         bdev = open_by_devnum(dev, FMODE_WRITE | FMODE_READ);
 314                 }
 315         }
 316 #endif
 317
 318         if (IS_ERR(bdev)) {
 319                 ERROR("error: cannot open device %s", devname);
 320                 goto devinit_err;
 321         }
 322         dev->blkdev = bdev;
 323
 324         if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
 325                 ERROR("attempting to use an MTD device as a block device");
 326                 goto devinit_err;
 327         }
 328
 329         mutex_init(&dev->write_mutex);
 330
 331         /* Setup the MTD structure */
 332         /* make the name contain the block device in */
 333         dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
 334                         GFP_KERNEL);
 335         if (!dev->mtd.name)
 336                 goto devinit_err;
 337
 338         sprintf(dev->mtd.name, "block2mtd: %s", devname);
 339
 340         dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
 341         dev->mtd.erasesize = erase_size;
 342         dev->mtd.writesize = 1;
 343         dev->mtd.type = MTD_RAM;
 344         dev->mtd.flags = MTD_CAP_RAM;
 345         dev->mtd.erase = block2mtd_erase;
 346         dev->mtd.write = block2mtd_write;
 347         dev->mtd.writev = default_mtd_writev;
 348         dev->mtd.sync = block2mtd_sync;
 349         dev->mtd.read = block2mtd_read;
 350         dev->mtd.priv = dev;
 351         dev->mtd.owner = THIS_MODULE;
 352
 353         if (add_mtd_device(&dev->mtd)) {
 354                 /* Device didnt get added, so free the entry */
 355                 goto devinit_err;
 356         }
 357         list_add(&dev->list, &blkmtd_device_list);
 358         INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
 359                         dev->mtd.name + strlen("blkmtd: "),
 360                         dev->mtd.erasesize >> 10, dev->mtd.erasesize);
 361         return dev;
 362
 363 devinit_err:
 364         block2mtd_free_device(dev);
 365         return NULL;
 366 }
 367
 368
 369 /* This function works similar to reguler strtoul.  In addition, it
 370  * allows some suffixes for a more human-readable number format:
 371  * ki, Ki, kiB, KiB     - multiply result with 1024
 372  * Mi, MiB              - multiply result with 1024^2
 373  * Gi, GiB              - multiply result with 1024^3
 374  */
 375 static int ustrtoul(const char *cp, char **endp, unsigned int base)
 376 {
 377         unsigned long result = simple_strtoul(cp, endp, base);
 378         switch (**endp) {
 379         case 'G' :
 380                 result *= 1024;
 381         case 'M':
 382                 result *= 1024;
 383         case 'K':
 384         case 'k':
 385                 result *= 1024;
 386         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 387                 if ((*endp)[1] == 'i') {
 388                         if ((*endp)[2] == 'B')
 389                                 (*endp) += 3;
 390                         else
 391                                 (*endp) += 2;
 392                 }
 393         }
 394         return result;
 395 }
 396
 397
 398 static int parse_num(size_t *num, const char *token)
 399 {
 400         char *endp;
 401         size_t n;
 402
 403         n = (size_t) ustrtoul(token, &endp, 0);
 404         if (*endp)
 405                 return -EINVAL;
 406
 407         *num = n;
 408         return 0;
 409 }
 410
 411
 412 static inline void kill_final_newline(char *str)
 413 {
 414         char *newline = strrchr(str, '\n');
 415         if (newline && !newline[1])
 416                 *newline = 0;
 417 }
 418
 419
 420 #define parse_err(fmt, args...) do {            \
 421         ERROR("block2mtd: " fmt "\n", ## args); \
 422         return 0;                               \
 423 } while (0)
 424
 425 #ifndef MODULE
 426 static int block2mtd_init_called = 0;
 427 static __initdata char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */
 428 #endif
 429
 430
 431 static int block2mtd_setup2(const char *val)
 432 {
 433         char buf[80 + 12]; /* 80 for device, 12 for erase size */
 434         char *str = buf;
 435         char *token[2];
 436         char *name;
 437         size_t erase_size = PAGE_SIZE;
 438         int i, ret;
 439
 440         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 441                 parse_err("parameter too long");
 442
 443         strcpy(str, val);
 444         kill_final_newline(str);
 445
 446         for (i = 0; i < 2; i++)
 447                 token[i] = strsep(&str, ",");
 448
 449         if (str)
 450                 parse_err("too many arguments");
 451
 452         if (!token[0])
 453                 parse_err("no argument");
 454
 455         name = token[0];
 456         if (strlen(name) + 1 > 80)
 457                 parse_err("device name too long");
 458
 459         if (token[1]) {
 460                 ret = parse_num(&erase_size, token[1]);
 461                 if (ret) {
 462                         kfree(name);
 463                         parse_err("illegal erase size");
 464                 }
 465         }
 466
 467         add_device(name, erase_size);
 468
 469         return 0;
 470 }
 471
 472
 473 static int block2mtd_setup(const char *val, struct kernel_param *kp)
 474 {
 475 #ifdef MODULE
 476         return block2mtd_setup2(val);
 477 #else
 478         /* If more parameters are later passed in via
 479            /sys/module/block2mtd/parameters/block2mtd
 480            and block2mtd_init() has already been called,
 481            we can parse the argument now. */
 482
 483         if (block2mtd_init_called)
 484                 return block2mtd_setup2(val);
 485
 486         /* During early boot stage, we only save the parameters
 487            here. We must parse them later: if the param passed
 488            from kernel boot command line, block2mtd_setup() is
 489            called so early that it is not possible to resolve
 490            the device (even kmalloc() fails). Deter that work to
 491            block2mtd_setup2(). */
 492
 493         strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
 494
 495         return 0;
 496 #endif
 497 }
 498
 499
 500 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
 501 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
 502
 503 static int __init block2mtd_init(void)
 504 {
 505         int ret = 0;
 506         INFO("version " VERSION);
 507
 508 #ifndef MODULE
 509         if (strlen(block2mtd_paramline))
 510                 ret = block2mtd_setup2(block2mtd_paramline);
 511         block2mtd_init_called = 1;
 512 #endif
 513
 514         return ret;
 515 }
 516
 517
 518 static void __devexit block2mtd_exit(void)
 519 {
 520         struct list_head *pos, *next;
 521
 522         /* Remove the MTD devices */
 523         list_for_each_safe(pos, next, &blkmtd_device_list) {
 524                 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
 525                 block2mtd_sync(&dev->mtd);
 526                 del_mtd_device(&dev->mtd);
 527                 INFO("mtd%d: [%s] removed", dev->mtd.index,
 528                                 dev->mtd.name + strlen("blkmtd: "));
 529                 list_del(&dev->list);
 530                 block2mtd_free_device(dev);
 531         }
 532 }
 533
 534
 535 module_init(block2mtd_init);
 536 module_exit(block2mtd_exit);
 537
 538 MODULE_LICENSE("GPL");
 539 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
 540 MODULE_DESCRIPTION("Emulate an MTD using a block device");