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) 2004,2005      Jörn Engel <joern@wh.fh-wedel.de>
   8  *
   9  * Licence: GPL
  10  */
  11 #include <linux/config.h>
  12 #include <linux/module.h>
  13 #include <linux/fs.h>
  14 #include <linux/blkdev.h>
  15 #include <linux/bio.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/list.h>
  18 #include <linux/init.h>
  19 #include <linux/mtd/mtd.h>
  20 #include <linux/buffer_head.h>
  21 #include <linux/mutex.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 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
 241                 size_t *retlen, const u_char *buf)
 242 {
 243         struct block2mtd_dev *dev = mtd->priv;
 244         int err;
 245
 246         if (!len)
 247                 return 0;
 248         if (to >= mtd->size)
 249                 return -ENOSPC;
 250         if (to + len > mtd->size)
 251                 len = mtd->size - to;
 252
 253         mutex_lock(&dev->write_mutex);
 254         err = _block2mtd_write(dev, buf, to, len, retlen);
 255         mutex_unlock(&dev->write_mutex);
 256         if (err > 0)
 257                 err = 0;
 258         return err;
 259 }
 260
 261
 262 /* sync the device - wait until the write queue is empty */
 263 static void block2mtd_sync(struct mtd_info *mtd)
 264 {
 265         struct block2mtd_dev *dev = mtd->priv;
 266         sync_blockdev(dev->blkdev);
 267         return;
 268 }
 269
 270
 271 static void block2mtd_free_device(struct block2mtd_dev *dev)
 272 {
 273         if (!dev)
 274                 return;
 275
 276         kfree(dev->mtd.name);
 277
 278         if (dev->blkdev) {
 279                 invalidate_inode_pages(dev->blkdev->bd_inode->i_mapping);
 280                 close_bdev_excl(dev->blkdev);
 281         }
 282
 283         kfree(dev);
 284 }
 285
 286
 287 /* FIXME: ensure that mtd->size % erase_size == 0 */
 288 static struct block2mtd_dev *add_device(char *devname, int erase_size)
 289 {
 290         struct block_device *bdev;
 291         struct block2mtd_dev *dev;
 292
 293         if (!devname)
 294                 return NULL;
 295
 296         dev = kmalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
 297         if (!dev)
 298                 return NULL;
 299         memset(dev, 0, sizeof(*dev));
 300
 301         /* Get a handle on the device */
 302         bdev = open_bdev_excl(devname, O_RDWR, NULL);
 303         if (IS_ERR(bdev)) {
 304                 ERROR("error: cannot open device %s", devname);
 305                 goto devinit_err;
 306         }
 307         dev->blkdev = bdev;
 308
 309         if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
 310                 ERROR("attempting to use an MTD device as a block device");
 311                 goto devinit_err;
 312         }
 313
 314         mutex_init(&dev->write_mutex);
 315
 316         /* Setup the MTD structure */
 317         /* make the name contain the block device in */
 318         dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
 319                         GFP_KERNEL);
 320         if (!dev->mtd.name)
 321                 goto devinit_err;
 322
 323         sprintf(dev->mtd.name, "block2mtd: %s", devname);
 324
 325         dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
 326         dev->mtd.erasesize = erase_size;
 327         dev->mtd.type = MTD_RAM;
 328         dev->mtd.flags = MTD_CAP_RAM;
 329         dev->mtd.erase = block2mtd_erase;
 330         dev->mtd.write = block2mtd_write;
 331         dev->mtd.writev = default_mtd_writev;
 332         dev->mtd.sync = block2mtd_sync;
 333         dev->mtd.read = block2mtd_read;
 334         dev->mtd.readv = default_mtd_readv;
 335         dev->mtd.priv = dev;
 336         dev->mtd.owner = THIS_MODULE;
 337
 338         if (add_mtd_device(&dev->mtd)) {
 339                 /* Device didnt get added, so free the entry */
 340                 goto devinit_err;
 341         }
 342         list_add(&dev->list, &blkmtd_device_list);
 343         INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
 344                         dev->mtd.name + strlen("blkmtd: "),
 345                         dev->mtd.erasesize >> 10, dev->mtd.erasesize);
 346         return dev;
 347
 348 devinit_err:
 349         block2mtd_free_device(dev);
 350         return NULL;
 351 }
 352
 353
 354 static int ustrtoul(const char *cp, char **endp, unsigned int base)
 355 {
 356         unsigned long result = simple_strtoul(cp, endp, base);
 357         switch (**endp) {
 358         case 'G' :
 359                 result *= 1024;
 360         case 'M':
 361                 result *= 1024;
 362         case 'k':
 363                 result *= 1024;
 364         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 365                 if ((*endp)[1] == 'i')
 366                         (*endp) += 2;
 367         }
 368         return result;
 369 }
 370
 371
 372 static int parse_num(size_t *num, const char *token)
 373 {
 374         char *endp;
 375         size_t n;
 376
 377         n = (size_t) ustrtoul(token, &endp, 0);
 378         if (*endp)
 379                 return -EINVAL;
 380
 381         *num = n;
 382         return 0;
 383 }
 384
 385
 386 static int parse_name(char **pname, const char *token, size_t limit)
 387 {
 388         size_t len;
 389         char *name;
 390
 391         len = strlen(token) + 1;
 392         if (len > limit)
 393                 return -ENOSPC;
 394
 395         name = kmalloc(len, GFP_KERNEL);
 396         if (!name)
 397                 return -ENOMEM;
 398
 399         strcpy(name, token);
 400
 401         *pname = name;
 402         return 0;
 403 }
 404
 405
 406 static inline void kill_final_newline(char *str)
 407 {
 408         char *newline = strrchr(str, '\n');
 409         if (newline && !newline[1])
 410                 *newline = 0;
 411 }
 412
 413
 414 #define parse_err(fmt, args...) do {            \
 415         ERROR("block2mtd: " fmt "\n", ## args); \
 416         return 0;                               \
 417 } while (0)
 418
 419 static int block2mtd_setup(const char *val, struct kernel_param *kp)
 420 {
 421         char buf[80+12], *str=buf; /* 80 for device, 12 for erase size */
 422         char *token[2];
 423         char *name;
 424         size_t erase_size = PAGE_SIZE;
 425         int i, ret;
 426
 427         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 428                 parse_err("parameter too long");
 429
 430         strcpy(str, val);
 431         kill_final_newline(str);
 432
 433         for (i=0; i<2; i++)
 434                 token[i] = strsep(&str, ",");
 435
 436         if (str)
 437                 parse_err("too many arguments");
 438
 439         if (!token[0])
 440                 parse_err("no argument");
 441
 442         ret = parse_name(&name, token[0], 80);
 443         if (ret == -ENOMEM)
 444                 parse_err("out of memory");
 445         if (ret == -ENOSPC)
 446                 parse_err("name too long");
 447         if (ret)
 448                 return 0;
 449
 450         if (token[1]) {
 451                 ret = parse_num(&erase_size, token[1]);
 452                 if (ret)
 453                         parse_err("illegal erase size");
 454         }
 455
 456         add_device(name, erase_size);
 457
 458         return 0;
 459 }
 460
 461
 462 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
 463 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
 464
 465 static int __init block2mtd_init(void)
 466 {
 467         INFO("version " VERSION);
 468         return 0;
 469 }
 470
 471
 472 static void __devexit block2mtd_exit(void)
 473 {
 474         struct list_head *pos, *next;
 475
 476         /* Remove the MTD devices */
 477         list_for_each_safe(pos, next, &blkmtd_device_list) {
 478                 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
 479                 block2mtd_sync(&dev->mtd);
 480                 del_mtd_device(&dev->mtd);
 481                 INFO("mtd%d: [%s] removed", dev->mtd.index,
 482                                 dev->mtd.name + strlen("blkmtd: "));
 483                 list_del(&dev->list);
 484                 block2mtd_free_device(dev);
 485         }
 486 }
 487
 488
 489 module_init(block2mtd_init);
 490 module_exit(block2mtd_exit);
 491
 492 MODULE_LICENSE("GPL");
 493 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
 494 MODULE_DESCRIPTION("Emulate an MTD using a block device");