drivers/mtd/devices/block2mtd.c

   1 /*
   2  * $Id: block2mtd.c,v 1.23 2005/01/05 17:05:46 dwmw2 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           Gareth Bult <Gareth@Encryptec.net>
   8  * Copyright (C) 2004,2005      Jörn Engel <joern@wh.fh-wedel.de>
   9  *
  10  * Licence: GPL
  11  */
  12 #include <linux/config.h>
  13 #include <linux/module.h>
  14 #include <linux/fs.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/bio.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/list.h>
  19 #include <linux/init.h>
  20 #include <linux/mtd/mtd.h>
  21 #include <linux/buffer_head.h>
  22
  23 #define VERSION "$Revision: 1.23 $"
  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 semaphore 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 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         //do_page_cache_readahead(mapping, index, XXX, 64);
  93         cache_readahead(mapping, index);
  94         return read_cache_page(mapping, index, filler, NULL);
  95 }
  96
  97
  98 /* erase a specified part of the device */
  99 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
 100 {
 101         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
 102         struct page *page;
 103         int index = to >> PAGE_SHIFT;   // page index
 104         int pages = len >> PAGE_SHIFT;
 105         u_long *p;
 106         u_long *max;
 107
 108         while (pages) {
 109                 page = page_readahead(mapping, index);
 110                 if (!page)
 111                         return -ENOMEM;
 112                 if (IS_ERR(page))
 113                         return PTR_ERR(page);
 114
 115                 max = (u_long*)page_address(page) + PAGE_SIZE;
 116                 for (p=(u_long*)page_address(page); p<max; p++)
 117                         if (*p != -1UL) {
 118                                 lock_page(page);
 119                                 memset(page_address(page), 0xff, PAGE_SIZE);
 120                                 set_page_dirty(page);
 121                                 unlock_page(page);
 122                                 break;
 123                         }
 124
 125                 page_cache_release(page);
 126                 pages--;
 127                 index++;
 128         }
 129         return 0;
 130 }
 131 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
 132 {
 133         struct block2mtd_dev *dev = mtd->priv;
 134         size_t from = instr->addr;
 135         size_t len = instr->len;
 136         int err;
 137
 138         instr->state = MTD_ERASING;
 139         down(&dev->write_mutex);
 140         err = _block2mtd_erase(dev, from, len);
 141         up(&dev->write_mutex);
 142         if (err) {
 143                 ERROR("erase failed err = %d", err);
 144                 instr->state = MTD_ERASE_FAILED;
 145         } else
 146                 instr->state = MTD_ERASE_DONE;
 147
 148         instr->state = MTD_ERASE_DONE;
 149         mtd_erase_callback(instr);
 150         return err;
 151 }
 152
 153
 154 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
 155                 size_t *retlen, u_char *buf)
 156 {
 157         struct block2mtd_dev *dev = mtd->priv;
 158         struct page *page;
 159         int index = from >> PAGE_SHIFT;
 160         int offset = from & (PAGE_SHIFT-1);
 161         int cpylen;
 162
 163         if (from > mtd->size)
 164                 return -EINVAL;
 165         if (from + len > mtd->size)
 166                 len = mtd->size - from;
 167
 168         if (retlen)
 169                 *retlen = 0;
 170
 171         while (len) {
 172                 if ((offset + len) > PAGE_SIZE)
 173                         cpylen = PAGE_SIZE - offset;    // multiple pages
 174                 else
 175                         cpylen = len;   // this page
 176                 len = len - cpylen;
 177
 178                 //      Get page
 179                 page = page_readahead(dev->blkdev->bd_inode->i_mapping, index);
 180                 if (!page)
 181                         return -ENOMEM;
 182                 if (IS_ERR(page))
 183                         return PTR_ERR(page);
 184
 185                 memcpy(buf, page_address(page) + offset, cpylen);
 186                 page_cache_release(page);
 187
 188                 if (retlen)
 189                         *retlen += cpylen;
 190                 buf += cpylen;
 191                 offset = 0;
 192                 index++;
 193         }
 194         return 0;
 195 }
 196
 197
 198 /* write data to the underlying device */
 199 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
 200                 loff_t to, size_t len, size_t *retlen)
 201 {
 202         struct page *page;
 203         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
 204         int index = to >> PAGE_SHIFT;   // page index
 205         int offset = to & ~PAGE_MASK;   // page offset
 206         int cpylen;
 207
 208         if (retlen)
 209                 *retlen = 0;
 210         while (len) {
 211                 if ((offset+len) > PAGE_SIZE)
 212                         cpylen = PAGE_SIZE - offset;    // multiple pages
 213                 else
 214                         cpylen = len;                   // this page
 215                 len = len - cpylen;
 216
 217                 //      Get page
 218                 page = page_readahead(mapping, index);
 219                 if (!page)
 220                         return -ENOMEM;
 221                 if (IS_ERR(page))
 222                         return PTR_ERR(page);
 223
 224                 if (memcmp(page_address(page)+offset, buf, cpylen)) {
 225                         lock_page(page);
 226                         memcpy(page_address(page) + offset, buf, cpylen);
 227                         set_page_dirty(page);
 228                         unlock_page(page);
 229                 }
 230                 page_cache_release(page);
 231
 232                 if (retlen)
 233                         *retlen += cpylen;
 234
 235                 buf += cpylen;
 236                 offset = 0;
 237                 index++;
 238         }
 239         return 0;
 240 }
 241 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
 242                 size_t *retlen, const u_char *buf)
 243 {
 244         struct block2mtd_dev *dev = mtd->priv;
 245         int err;
 246
 247         if (!len)
 248                 return 0;
 249         if (to >= mtd->size)
 250                 return -ENOSPC;
 251         if (to + len > mtd->size)
 252                 len = mtd->size - to;
 253
 254         down(&dev->write_mutex);
 255         err = _block2mtd_write(dev, buf, to, len, retlen);
 256         up(&dev->write_mutex);
 257         if (err > 0)
 258                 err = 0;
 259         return err;
 260 }
 261
 262
 263 /* sync the device - wait until the write queue is empty */
 264 static void block2mtd_sync(struct mtd_info *mtd)
 265 {
 266         struct block2mtd_dev *dev = mtd->priv;
 267         sync_blockdev(dev->blkdev);
 268         return;
 269 }
 270
 271
 272 static void block2mtd_free_device(struct block2mtd_dev *dev)
 273 {
 274         if (!dev)
 275                 return;
 276
 277         kfree(dev->mtd.name);
 278
 279         if (dev->blkdev) {
 280                 invalidate_inode_pages(dev->blkdev->bd_inode->i_mapping);
 281                 close_bdev_excl(dev->blkdev);
 282         }
 283
 284         kfree(dev);
 285 }
 286
 287
 288 /* FIXME: ensure that mtd->size % erase_size == 0 */
 289 static struct block2mtd_dev *add_device(char *devname, int erase_size)
 290 {
 291         struct block_device *bdev;
 292         struct block2mtd_dev *dev;
 293
 294         if (!devname)
 295                 return NULL;
 296
 297         dev = kmalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
 298         if (!dev)
 299                 return NULL;
 300         memset(dev, 0, sizeof(*dev));
 301
 302         /* Get a handle on the device */
 303         bdev = open_bdev_excl(devname, O_RDWR, NULL);
 304         if (IS_ERR(bdev)) {
 305                 ERROR("error: cannot open device %s", devname);
 306                 goto devinit_err;
 307         }
 308         dev->blkdev = bdev;
 309
 310         if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
 311                 ERROR("attempting to use an MTD device as a block device");
 312                 goto devinit_err;
 313         }
 314
 315         init_MUTEX(&dev->write_mutex);
 316
 317         /* Setup the MTD structure */
 318         /* make the name contain the block device in */
 319         dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
 320                         GFP_KERNEL);
 321         if (!dev->mtd.name)
 322                 goto devinit_err;
 323
 324         sprintf(dev->mtd.name, "block2mtd: %s", devname);
 325
 326         dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
 327         dev->mtd.erasesize = erase_size;
 328         dev->mtd.type = MTD_RAM;
 329         dev->mtd.flags = MTD_CAP_RAM;
 330         dev->mtd.erase = block2mtd_erase;
 331         dev->mtd.write = block2mtd_write;
 332         dev->mtd.writev = default_mtd_writev;
 333         dev->mtd.sync = block2mtd_sync;
 334         dev->mtd.read = block2mtd_read;
 335         dev->mtd.readv = default_mtd_readv;
 336         dev->mtd.priv = dev;
 337         dev->mtd.owner = THIS_MODULE;
 338
 339         if (add_mtd_device(&dev->mtd)) {
 340                 /* Device didnt get added, so free the entry */
 341                 goto devinit_err;
 342         }
 343         list_add(&dev->list, &blkmtd_device_list);
 344         INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
 345                         dev->mtd.name + strlen("blkmtd: "),
 346                         dev->mtd.erasesize >> 10, dev->mtd.erasesize);
 347         return dev;
 348
 349 devinit_err:
 350         block2mtd_free_device(dev);
 351         return NULL;
 352 }
 353
 354
 355 static int ustrtoul(const char *cp, char **endp, unsigned int base)
 356 {
 357         unsigned long result = simple_strtoul(cp, endp, base);
 358         switch (**endp) {
 359         case 'G' :
 360                 result *= 1024;
 361         case 'M':
 362                 result *= 1024;
 363         case 'k':
 364                 result *= 1024;
 365         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 366                 if ((*endp)[1] == 'i')
 367                         (*endp) += 2;
 368         }
 369         return result;
 370 }
 371
 372
 373 static int parse_num32(u32 *num32, const char *token)
 374 {
 375         char *endp;
 376         unsigned long n;
 377
 378         n = ustrtoul(token, &endp, 0);
 379         if (*endp)
 380                 return -EINVAL;
 381
 382         *num32 = n;
 383         return 0;
 384 }
 385
 386
 387 static int parse_name(char **pname, const char *token, size_t limit)
 388 {
 389         size_t len;
 390         char *name;
 391
 392         len = strlen(token) + 1;
 393         if (len > limit)
 394                 return -ENOSPC;
 395
 396         name = kmalloc(len, GFP_KERNEL);
 397         if (!name)
 398                 return -ENOMEM;
 399
 400         strcpy(name, token);
 401
 402         *pname = name;
 403         return 0;
 404 }
 405
 406
 407 static inline void kill_final_newline(char *str)
 408 {
 409         char *newline = strrchr(str, '\n');
 410         if (newline && !newline[1])
 411                 *newline = 0;
 412 }
 413
 414
 415 #define parse_err(fmt, args...) do {            \
 416         ERROR("block2mtd: " fmt "\n", ## args); \
 417         return 0;                               \
 418 } while (0)
 419
 420 static int block2mtd_setup(const char *val, struct kernel_param *kp)
 421 {
 422         char buf[80+12], *str=buf; /* 80 for device, 12 for erase size */
 423         char *token[2];
 424         char *name;
 425         u32 erase_size = PAGE_SIZE;
 426         int i, ret;
 427
 428         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 429                 parse_err("parameter too long");
 430
 431         strcpy(str, val);
 432         kill_final_newline(str);
 433
 434         for (i=0; i<2; i++)
 435                 token[i] = strsep(&str, ",");
 436
 437         if (str)
 438                 parse_err("too many arguments");
 439
 440         if (!token[0])
 441                 parse_err("no argument");
 442
 443         ret = parse_name(&name, token[0], 80);
 444         if (ret == -ENOMEM)
 445                 parse_err("out of memory");
 446         if (ret == -ENOSPC)
 447                 parse_err("name too long");
 448         if (ret)
 449                 return 0;
 450
 451         if (token[1]) {
 452                 ret = parse_num32(&erase_size, token[1]);
 453                 if (ret)
 454                         parse_err("illegal erase size");
 455         }
 456
 457         add_device(name, erase_size);
 458
 459         return 0;
 460 }
 461
 462
 463 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
 464 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
 465
 466 static int __init block2mtd_init(void)
 467 {
 468         INFO("version " VERSION);
 469         return 0;
 470 }
 471
 472
 473 static void __devexit block2mtd_exit(void)
 474 {
 475         struct list_head *pos, *next;
 476
 477         /* Remove the MTD devices */
 478         list_for_each_safe(pos, next, &blkmtd_device_list) {
 479                 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
 480                 block2mtd_sync(&dev->mtd);
 481                 del_mtd_device(&dev->mtd);
 482                 INFO("mtd%d: [%s] removed", dev->mtd.index,
 483                                 dev->mtd.name + strlen("blkmtd: "));
 484                 list_del(&dev->list);
 485                 block2mtd_free_device(dev);
 486         }
 487 }
 488
 489
 490 module_init(block2mtd_init);
 491 module_exit(block2mtd_exit);
 492
 493 MODULE_LICENSE("GPL");
 494 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
 495 MODULE_DESCRIPTION("Emulate an MTD using a block device");