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
  22 #define VERSION "$Revision: 1.30 $"
  23
  24
  25 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
  26 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
  27
  28
  29 /* Info for the block device */
  30 struct block2mtd_dev {
  31         struct list_head list;
  32         struct block_device *blkdev;
  33         struct mtd_info mtd;
  34         struct semaphore write_mutex;
  35 };
  36
  37
  38 /* Static info about the MTD, used in cleanup_module */
  39 static LIST_HEAD(blkmtd_device_list);
  40
  41
  42 #define PAGE_READAHEAD 64
  43 static void cache_readahead(struct address_space *mapping, int index)
  44 {
  45         filler_t *filler = (filler_t*)mapping->a_ops->readpage;
  46         int i, pagei;
  47         unsigned ret = 0;
  48         unsigned long end_index;
  49         struct page *page;
  50         LIST_HEAD(page_pool);
  51         struct inode *inode = mapping->host;
  52         loff_t isize = i_size_read(inode);
  53
  54         if (!isize) {
  55                 INFO("iSize=0 in cache_readahead\n");
  56                 return;
  57         }
  58
  59         end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);
  60
  61         read_lock_irq(&mapping->tree_lock);
  62         for (i = 0; i < PAGE_READAHEAD; i++) {
  63                 pagei = index + i;
  64                 if (pagei > end_index) {
  65                         INFO("Overrun end of disk in cache readahead\n");
  66                         break;
  67                 }
  68                 page = radix_tree_lookup(&mapping->page_tree, pagei);
  69                 if (page && (!i))
  70                         break;
  71                 if (page)
  72                         continue;
  73                 read_unlock_irq(&mapping->tree_lock);
  74                 page = page_cache_alloc_cold(mapping);
  75                 read_lock_irq(&mapping->tree_lock);
  76                 if (!page)
  77                         break;
  78                 page->index = pagei;
  79                 list_add(&page->lru, &page_pool);
  80                 ret++;
  81         }
  82         read_unlock_irq(&mapping->tree_lock);
  83         if (ret)
  84                 read_cache_pages(mapping, &page_pool, filler, NULL);
  85 }
  86
  87
  88 static struct page* page_readahead(struct address_space *mapping, int index)
  89 {
  90         filler_t *filler = (filler_t*)mapping->a_ops->readpage;
  91         cache_readahead(mapping, index);
  92         return read_cache_page(mapping, index, filler, NULL);
  93 }
  94
  95
  96 /* erase a specified part of the device */
  97 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
  98 {
  99         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
 100         struct page *page;
 101         int index = to >> PAGE_SHIFT;   // page index
 102         int pages = len >> PAGE_SHIFT;
 103         u_long *p;
 104         u_long *max;
 105
 106         while (pages) {
 107                 page = page_readahead(mapping, index);
 108                 if (!page)
 109                         return -ENOMEM;
 110                 if (IS_ERR(page))
 111                         return PTR_ERR(page);
 112
 113                 max = (u_long*)page_address(page) + PAGE_SIZE;
 114                 for (p=(u_long*)page_address(page); p<max; p++)
 115                         if (*p != -1UL) {
 116                                 lock_page(page);
 117                                 memset(page_address(page), 0xff, PAGE_SIZE);
 118                                 set_page_dirty(page);
 119                                 unlock_page(page);
 120                                 break;
 121                         }
 122
 123                 page_cache_release(page);
 124                 pages--;
 125                 index++;
 126         }
 127         return 0;
 128 }
 129 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
 130 {
 131         struct block2mtd_dev *dev = mtd->priv;
 132         size_t from = instr->addr;
 133         size_t len = instr->len;
 134         int err;
 135
 136         instr->state = MTD_ERASING;
 137         down(&dev->write_mutex);
 138         err = _block2mtd_erase(dev, from, len);
 139         up(&dev->write_mutex);
 140         if (err) {
 141                 ERROR("erase failed err = %d", err);
 142                 instr->state = MTD_ERASE_FAILED;
 143         } else
 144                 instr->state = MTD_ERASE_DONE;
 145
 146         instr->state = MTD_ERASE_DONE;
 147         mtd_erase_callback(instr);
 148         return err;
 149 }
 150
 151
 152 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
 153                 size_t *retlen, u_char *buf)
 154 {
 155         struct block2mtd_dev *dev = mtd->priv;
 156         struct page *page;
 157         int index = from >> PAGE_SHIFT;
 158         int offset = from & (PAGE_SIZE-1);
 159         int cpylen;
 160
 161         if (from > mtd->size)
 162                 return -EINVAL;
 163         if (from + len > mtd->size)
 164                 len = mtd->size - from;
 165
 166         if (retlen)
 167                 *retlen = 0;
 168
 169         while (len) {
 170                 if ((offset + len) > PAGE_SIZE)
 171                         cpylen = PAGE_SIZE - offset;    // multiple pages
 172                 else
 173                         cpylen = len;   // this page
 174                 len = len - cpylen;
 175
 176                 //      Get page
 177                 page = page_readahead(dev->blkdev->bd_inode->i_mapping, index);
 178                 if (!page)
 179                         return -ENOMEM;
 180                 if (IS_ERR(page))
 181                         return PTR_ERR(page);
 182
 183                 memcpy(buf, page_address(page) + offset, cpylen);
 184                 page_cache_release(page);
 185
 186                 if (retlen)
 187                         *retlen += cpylen;
 188                 buf += cpylen;
 189                 offset = 0;
 190                 index++;
 191         }
 192         return 0;
 193 }
 194
 195
 196 /* write data to the underlying device */
 197 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
 198                 loff_t to, size_t len, size_t *retlen)
 199 {
 200         struct page *page;
 201         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
 202         int index = to >> PAGE_SHIFT;   // page index
 203         int offset = to & ~PAGE_MASK;   // page offset
 204         int cpylen;
 205
 206         if (retlen)
 207                 *retlen = 0;
 208         while (len) {
 209                 if ((offset+len) > PAGE_SIZE)
 210                         cpylen = PAGE_SIZE - offset;    // multiple pages
 211                 else
 212                         cpylen = len;                   // this page
 213                 len = len - cpylen;
 214
 215                 //      Get page
 216                 page = page_readahead(mapping, index);
 217                 if (!page)
 218                         return -ENOMEM;
 219                 if (IS_ERR(page))
 220                         return PTR_ERR(page);
 221
 222                 if (memcmp(page_address(page)+offset, buf, cpylen)) {
 223                         lock_page(page);
 224                         memcpy(page_address(page) + offset, buf, cpylen);
 225                         set_page_dirty(page);
 226                         unlock_page(page);
 227                 }
 228                 page_cache_release(page);
 229
 230                 if (retlen)
 231                         *retlen += cpylen;
 232
 233                 buf += cpylen;
 234                 offset = 0;
 235                 index++;
 236         }
 237         return 0;
 238 }
 239 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
 240                 size_t *retlen, const u_char *buf)
 241 {
 242         struct block2mtd_dev *dev = mtd->priv;
 243         int err;
 244
 245         if (!len)
 246                 return 0;
 247         if (to >= mtd->size)
 248                 return -ENOSPC;
 249         if (to + len > mtd->size)
 250                 len = mtd->size - to;
 251
 252         down(&dev->write_mutex);
 253         err = _block2mtd_write(dev, buf, to, len, retlen);
 254         up(&dev->write_mutex);
 255         if (err > 0)
 256                 err = 0;
 257         return err;
 258 }
 259
 260
 261 /* sync the device - wait until the write queue is empty */
 262 static void block2mtd_sync(struct mtd_info *mtd)
 263 {
 264         struct block2mtd_dev *dev = mtd->priv;
 265         sync_blockdev(dev->blkdev);
 266         return;
 267 }
 268
 269
 270 static void block2mtd_free_device(struct block2mtd_dev *dev)
 271 {
 272         if (!dev)
 273                 return;
 274
 275         kfree(dev->mtd.name);
 276
 277         if (dev->blkdev) {
 278                 invalidate_inode_pages(dev->blkdev->bd_inode->i_mapping);
 279                 close_bdev_excl(dev->blkdev);
 280         }
 281
 282         kfree(dev);
 283 }
 284
 285
 286 /* FIXME: ensure that mtd->size % erase_size == 0 */
 287 static struct block2mtd_dev *add_device(char *devname, int erase_size)
 288 {
 289         struct block_device *bdev;
 290         struct block2mtd_dev *dev;
 291
 292         if (!devname)
 293                 return NULL;
 294
 295         dev = kmalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
 296         if (!dev)
 297                 return NULL;
 298         memset(dev, 0, sizeof(*dev));
 299
 300         /* Get a handle on the device */
 301         bdev = open_bdev_excl(devname, O_RDWR, NULL);
 302         if (IS_ERR(bdev)) {
 303                 ERROR("error: cannot open device %s", devname);
 304                 goto devinit_err;
 305         }
 306         dev->blkdev = bdev;
 307
 308         if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
 309                 ERROR("attempting to use an MTD device as a block device");
 310                 goto devinit_err;
 311         }
 312
 313         init_MUTEX(&dev->write_mutex);
 314
 315         /* Setup the MTD structure */
 316         /* make the name contain the block device in */
 317         dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
 318                         GFP_KERNEL);
 319         if (!dev->mtd.name)
 320                 goto devinit_err;
 321
 322         sprintf(dev->mtd.name, "block2mtd: %s", devname);
 323
 324         dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
 325         dev->mtd.erasesize = erase_size;
 326         dev->mtd.type = MTD_RAM;
 327         dev->mtd.flags = MTD_CAP_RAM;
 328         dev->mtd.erase = block2mtd_erase;
 329         dev->mtd.write = block2mtd_write;
 330         dev->mtd.writev = default_mtd_writev;
 331         dev->mtd.sync = block2mtd_sync;
 332         dev->mtd.read = block2mtd_read;
 333         dev->mtd.readv = default_mtd_readv;
 334         dev->mtd.priv = dev;
 335         dev->mtd.owner = THIS_MODULE;
 336
 337         if (add_mtd_device(&dev->mtd)) {
 338                 /* Device didnt get added, so free the entry */
 339                 goto devinit_err;
 340         }
 341         list_add(&dev->list, &blkmtd_device_list);
 342         INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
 343                         dev->mtd.name + strlen("blkmtd: "),
 344                         dev->mtd.erasesize >> 10, dev->mtd.erasesize);
 345         return dev;
 346
 347 devinit_err:
 348         block2mtd_free_device(dev);
 349         return NULL;
 350 }
 351
 352
 353 static int ustrtoul(const char *cp, char **endp, unsigned int base)
 354 {
 355         unsigned long result = simple_strtoul(cp, endp, base);
 356         switch (**endp) {
 357         case 'G' :
 358                 result *= 1024;
 359         case 'M':
 360                 result *= 1024;
 361         case 'k':
 362                 result *= 1024;
 363         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 364                 if ((*endp)[1] == 'i')
 365                         (*endp) += 2;
 366         }
 367         return result;
 368 }
 369
 370
 371 static int parse_num(size_t *num, const char *token)
 372 {
 373         char *endp;
 374         size_t n;
 375
 376         n = (size_t) ustrtoul(token, &endp, 0);
 377         if (*endp)
 378                 return -EINVAL;
 379
 380         *num = n;
 381         return 0;
 382 }
 383
 384
 385 static int parse_name(char **pname, const char *token, size_t limit)
 386 {
 387         size_t len;
 388         char *name;
 389
 390         len = strlen(token) + 1;
 391         if (len > limit)
 392                 return -ENOSPC;
 393
 394         name = kmalloc(len, GFP_KERNEL);
 395         if (!name)
 396                 return -ENOMEM;
 397
 398         strcpy(name, token);
 399
 400         *pname = name;
 401         return 0;
 402 }
 403
 404
 405 static inline void kill_final_newline(char *str)
 406 {
 407         char *newline = strrchr(str, '\n');
 408         if (newline && !newline[1])
 409                 *newline = 0;
 410 }
 411
 412
 413 #define parse_err(fmt, args...) do {            \
 414         ERROR("block2mtd: " fmt "\n", ## args); \
 415         return 0;                               \
 416 } while (0)
 417
 418 static int block2mtd_setup(const char *val, struct kernel_param *kp)
 419 {
 420         char buf[80+12], *str=buf; /* 80 for device, 12 for erase size */
 421         char *token[2];
 422         char *name;
 423         size_t erase_size = PAGE_SIZE;
 424         int i, ret;
 425
 426         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 427                 parse_err("parameter too long");
 428
 429         strcpy(str, val);
 430         kill_final_newline(str);
 431
 432         for (i=0; i<2; i++)
 433                 token[i] = strsep(&str, ",");
 434
 435         if (str)
 436                 parse_err("too many arguments");
 437
 438         if (!token[0])
 439                 parse_err("no argument");
 440
 441         ret = parse_name(&name, token[0], 80);
 442         if (ret == -ENOMEM)
 443                 parse_err("out of memory");
 444         if (ret == -ENOSPC)
 445                 parse_err("name too long");
 446         if (ret)
 447                 return 0;
 448
 449         if (token[1]) {
 450                 ret = parse_num(&erase_size, token[1]);
 451                 if (ret)
 452                         parse_err("illegal erase size");
 453         }
 454
 455         add_device(name, erase_size);
 456
 457         return 0;
 458 }
 459
 460
 461 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
 462 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
 463
 464 static int __init block2mtd_init(void)
 465 {
 466         INFO("version " VERSION);
 467         return 0;
 468 }
 469
 470
 471 static void __devexit block2mtd_exit(void)
 472 {
 473         struct list_head *pos, *next;
 474
 475         /* Remove the MTD devices */
 476         list_for_each_safe(pos, next, &blkmtd_device_list) {
 477                 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
 478                 block2mtd_sync(&dev->mtd);
 479                 del_mtd_device(&dev->mtd);
 480                 INFO("mtd%d: [%s] removed", dev->mtd.index,
 481                                 dev->mtd.name + strlen("blkmtd: "));
 482                 list_del(&dev->list);
 483                 block2mtd_free_device(dev);
 484         }
 485 }
 486
 487
 488 module_init(block2mtd_init);
 489 module_exit(block2mtd_exit);
 490
 491 MODULE_LICENSE("GPL");
 492 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
 493 MODULE_DESCRIPTION("Emulate an MTD using a block device");