1/* 2 * Copyright (C) 2004, OGAWA Hirofumi 3 * Released under GPL v2. 4 */ 5 6#include <linux/module.h> 7#include <linux/fs.h> 8#include <linux/msdos_fs.h> 9 10struct fatent_operations { 11 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *); 12 void (*ent_set_ptr)(struct fat_entry *, int); 13 int (*ent_bread)(struct super_block *, struct fat_entry *, 14 int, sector_t); 15 int (*ent_get)(struct fat_entry *); 16 void (*ent_put)(struct fat_entry *, int); 17 int (*ent_next)(struct fat_entry *); 18}; 19 20static void fat12_ent_blocknr(struct super_block *sb, int entry, 21 int *offset, sector_t *blocknr) 22{ 23 struct msdos_sb_info *sbi = MSDOS_SB(sb); 24 int bytes = entry + (entry >> 1); 25 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); 26 *offset = bytes & (sb->s_blocksize - 1); 27 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 28} 29 30static void fat_ent_blocknr(struct super_block *sb, int entry, 31 int *offset, sector_t *blocknr) 32{ 33 struct msdos_sb_info *sbi = MSDOS_SB(sb); 34 int bytes = (entry << sbi->fatent_shift); 35 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); 36 *offset = bytes & (sb->s_blocksize - 1); 37 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 38} 39 40static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset) 41{ 42 struct buffer_head **bhs = fatent->bhs; 43 if (fatent->nr_bhs == 1) { 44 WARN_ON(offset >= (bhs[0]->b_size - 1)); 45 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 46 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1); 47 } else { 48 WARN_ON(offset != (bhs[0]->b_size - 1)); 49 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 50 fatent->u.ent12_p[1] = bhs[1]->b_data; 51 } 52} 53 54static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset) 55{ 56 WARN_ON(offset & (2 - 1)); 57 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset); 58} 59 60static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset) 61{ 62 WARN_ON(offset & (4 - 1)); 63 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset); 64} 65 66static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent, 67 int offset, sector_t blocknr) 68{ 69 struct buffer_head **bhs = fatent->bhs; 70 71 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 72 bhs[0] = sb_bread(sb, blocknr); 73 if (!bhs[0]) 74 goto err; 75 76 if ((offset + 1) < sb->s_blocksize) 77 fatent->nr_bhs = 1; 78 else { 79 /* This entry is block boundary, it needs the next block */ 80 blocknr++; 81 bhs[1] = sb_bread(sb, blocknr); 82 if (!bhs[1]) 83 goto err_brelse; 84 fatent->nr_bhs = 2; 85 } 86 fat12_ent_set_ptr(fatent, offset); 87 return 0; 88 89err_brelse: 90 brelse(bhs[0]); 91err: 92 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n", 93 (unsigned long long)blocknr); 94 return -EIO; 95} 96 97static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent, 98 int offset, sector_t blocknr) 99{ 100 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 101 102 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 103 fatent->bhs[0] = sb_bread(sb, blocknr); 104 if (!fatent->bhs[0]) { 105 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n", 106 (unsigned long long)blocknr); 107 return -EIO; 108 } 109 fatent->nr_bhs = 1; 110 ops->ent_set_ptr(fatent, offset); 111 return 0; 112} 113 114static int fat12_ent_get(struct fat_entry *fatent) 115{ 116 u8 **ent12_p = fatent->u.ent12_p; 117 int next; 118 119 if (fatent->entry & 1) 120 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4); 121 else 122 next = (*ent12_p[1] << 8) | *ent12_p[0]; 123 next &= 0x0fff; 124 if (next >= BAD_FAT12) 125 next = FAT_ENT_EOF; 126 return next; 127} 128 129static int fat16_ent_get(struct fat_entry *fatent) 130{ 131 int next = le16_to_cpu(*fatent->u.ent16_p); 132 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1)); 133 if (next >= BAD_FAT16) 134 next = FAT_ENT_EOF; 135 return next; 136} 137 138static int fat32_ent_get(struct fat_entry *fatent) 139{ 140 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff; 141 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1)); 142 if (next >= BAD_FAT32) 143 next = FAT_ENT_EOF; 144 return next; 145} 146 147static void fat12_ent_put(struct fat_entry *fatent, int new) 148{ 149 u8 **ent12_p = fatent->u.ent12_p; 150 151 if (new == FAT_ENT_EOF) 152 new = EOF_FAT12; 153 154 if (fatent->entry & 1) { 155 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f); 156 *ent12_p[1] = new >> 4; 157 } else { 158 *ent12_p[0] = new & 0xff; 159 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8); 160 } 161 162 mark_buffer_dirty(fatent->bhs[0]); 163 if (fatent->nr_bhs == 2) 164 mark_buffer_dirty(fatent->bhs[1]); 165} 166 167static void fat16_ent_put(struct fat_entry *fatent, int new) 168{ 169 if (new == FAT_ENT_EOF) 170 new = EOF_FAT16; 171 172 *fatent->u.ent16_p = cpu_to_le16(new); 173 mark_buffer_dirty(fatent->bhs[0]); 174} 175 176static void fat32_ent_put(struct fat_entry *fatent, int new) 177{ 178 if (new == FAT_ENT_EOF) 179 new = EOF_FAT32; 180 181 WARN_ON(new & 0xf0000000); 182 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; 183 *fatent->u.ent32_p = cpu_to_le32(new); 184 mark_buffer_dirty(fatent->bhs[0]); 185} 186 187static int fat12_ent_next(struct fat_entry *fatent) 188{ 189 u8 **ent12_p = fatent->u.ent12_p; 190 struct buffer_head **bhs = fatent->bhs; 191 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); 192 193 fatent->entry++; 194 if (fatent->nr_bhs == 1) { 195 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2))); 196 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))); 197 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { 198 ent12_p[0] = nextp - 1; 199 ent12_p[1] = nextp; 200 return 1; 201 } 202 } else { 203 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))); 204 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); 205 ent12_p[0] = nextp - 1; 206 ent12_p[1] = nextp; 207 brelse(bhs[0]); 208 bhs[0] = bhs[1]; 209 fatent->nr_bhs = 1; 210 return 1; 211 } 212 ent12_p[0] = NULL; 213 ent12_p[1] = NULL; 214 return 0; 215} 216 217static int fat16_ent_next(struct fat_entry *fatent) 218{ 219 const struct buffer_head *bh = fatent->bhs[0]; 220 fatent->entry++; 221 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { 222 fatent->u.ent16_p++; 223 return 1; 224 } 225 fatent->u.ent16_p = NULL; 226 return 0; 227} 228 229static int fat32_ent_next(struct fat_entry *fatent) 230{ 231 const struct buffer_head *bh = fatent->bhs[0]; 232 fatent->entry++; 233 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { 234 fatent->u.ent32_p++; 235 return 1; 236 } 237 fatent->u.ent32_p = NULL; 238 return 0; 239} 240 241static struct fatent_operations fat12_ops = { 242 .ent_blocknr = fat12_ent_blocknr, 243 .ent_set_ptr = fat12_ent_set_ptr, 244 .ent_bread = fat12_ent_bread, 245 .ent_get = fat12_ent_get, 246 .ent_put = fat12_ent_put, 247 .ent_next = fat12_ent_next, 248}; 249 250static struct fatent_operations fat16_ops = { 251 .ent_blocknr = fat_ent_blocknr, 252 .ent_set_ptr = fat16_ent_set_ptr, 253 .ent_bread = fat_ent_bread, 254 .ent_get = fat16_ent_get, 255 .ent_put = fat16_ent_put, 256 .ent_next = fat16_ent_next, 257}; 258 259static struct fatent_operations fat32_ops = { 260 .ent_blocknr = fat_ent_blocknr, 261 .ent_set_ptr = fat32_ent_set_ptr, 262 .ent_bread = fat_ent_bread, 263 .ent_get = fat32_ent_get, 264 .ent_put = fat32_ent_put, 265 .ent_next = fat32_ent_next, 266}; 267 268static inline void lock_fat(struct msdos_sb_info *sbi) 269{ 270 mutex_lock(&sbi->fat_lock); 271} 272 273static inline void unlock_fat(struct msdos_sb_info *sbi) 274{ 275 mutex_unlock(&sbi->fat_lock); 276} 277 278void fat_ent_access_init(struct super_block *sb) 279{ 280 struct msdos_sb_info *sbi = MSDOS_SB(sb); 281 282 mutex_init(&sbi->fat_lock); 283 284 switch (sbi->fat_bits) { 285 case 32: 286 sbi->fatent_shift = 2; 287 sbi->fatent_ops = &fat32_ops; 288 break; 289 case 16: 290 sbi->fatent_shift = 1; 291 sbi->fatent_ops = &fat16_ops; 292 break; 293 case 12: 294 sbi->fatent_shift = -1; 295 sbi->fatent_ops = &fat12_ops; 296 break; 297 } 298} 299 300static inline int fat_ent_update_ptr(struct super_block *sb, 301 struct fat_entry *fatent, 302 int offset, sector_t blocknr) 303{ 304 struct msdos_sb_info *sbi = MSDOS_SB(sb); 305 struct fatent_operations *ops = sbi->fatent_ops; 306 struct buffer_head **bhs = fatent->bhs; 307 308 /* Is this fatent's blocks including this entry? */ 309 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 310 return 0; 311 /* Does this entry need the next block? */ 312 if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) { 313 if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1)) 314 return 0; 315 } 316 ops->ent_set_ptr(fatent, offset); 317 return 1; 318} 319 320int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 321{ 322 struct super_block *sb = inode->i_sb; 323 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 324 struct fatent_operations *ops = sbi->fatent_ops; 325 int err, offset; 326 sector_t blocknr; 327 328 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) { 329 fatent_brelse(fatent); 330 fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry); 331 return -EIO; 332 } 333 334 fatent_set_entry(fatent, entry); 335 ops->ent_blocknr(sb, entry, &offset, &blocknr); 336 337 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 338 fatent_brelse(fatent); 339 err = ops->ent_bread(sb, fatent, offset, blocknr); 340 if (err) 341 return err; 342 } 343 return ops->ent_get(fatent); 344} 345 346static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 347 int nr_bhs) 348{ 349 struct msdos_sb_info *sbi = MSDOS_SB(sb); 350 struct buffer_head *c_bh; 351 int err, n, copy; 352 353 err = 0; 354 for (copy = 1; copy < sbi->fats; copy++) { 355 sector_t backup_fat = sbi->fat_length * copy; 356 357 for (n = 0; n < nr_bhs; n++) { 358 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 359 if (!c_bh) { 360 err = -ENOMEM; 361 goto error; 362 } 363 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 364 set_buffer_uptodate(c_bh); 365 mark_buffer_dirty(c_bh); 366 if (sb->s_flags & MS_SYNCHRONOUS) 367 err = sync_dirty_buffer(c_bh); 368 brelse(c_bh); 369 if (err) 370 goto error; 371 } 372 } 373error: 374 return err; 375} 376 377int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 378 int new, int wait) 379{ 380 struct super_block *sb = inode->i_sb; 381 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 382 int err; 383 384 ops->ent_put(fatent, new); 385 if (wait) { 386 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 387 if (err) 388 return err; 389 } 390 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 391} 392 393static inline int fat_ent_next(struct msdos_sb_info *sbi, 394 struct fat_entry *fatent) 395{ 396 if (sbi->fatent_ops->ent_next(fatent)) { 397 if (fatent->entry < sbi->max_cluster) 398 return 1; 399 } 400 return 0; 401} 402 403static inline int fat_ent_read_block(struct super_block *sb, 404 struct fat_entry *fatent) 405{ 406 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 407 sector_t blocknr; 408 int offset; 409 410 fatent_brelse(fatent); 411 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 412 return ops->ent_bread(sb, fatent, offset, blocknr); 413} 414 415static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 416 struct fat_entry *fatent) 417{ 418 int n, i; 419 420 for (n = 0; n < fatent->nr_bhs; n++) { 421 for (i = 0; i < *nr_bhs; i++) { 422 if (fatent->bhs[n] == bhs[i]) 423 break; 424 } 425 if (i == *nr_bhs) { 426 get_bh(fatent->bhs[n]); 427 bhs[i] = fatent->bhs[n]; 428 (*nr_bhs)++; 429 } 430 } 431} 432 433int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 434{ 435 struct super_block *sb = inode->i_sb; 436 struct msdos_sb_info *sbi = MSDOS_SB(sb); 437 struct fatent_operations *ops = sbi->fatent_ops; 438 struct fat_entry fatent, prev_ent; 439 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 440 int i, count, err, nr_bhs, idx_clus; 441 442 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 443 444 lock_fat(sbi); 445 if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) { 446 unlock_fat(sbi); 447 return -ENOSPC; 448 } 449 450 err = nr_bhs = idx_clus = 0; 451 count = FAT_START_ENT; 452 fatent_init(&prev_ent); 453 fatent_init(&fatent); 454 fatent_set_entry(&fatent, sbi->prev_free + 1); 455 while (count < sbi->max_cluster) { 456 if (fatent.entry >= sbi->max_cluster) 457 fatent.entry = FAT_START_ENT; 458 fatent_set_entry(&fatent, fatent.entry); 459 err = fat_ent_read_block(sb, &fatent); 460 if (err) 461 goto out; 462 463 /* Find the free entries in a block */ 464 do { 465 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 466 int entry = fatent.entry; 467 468 /* make the cluster chain */ 469 ops->ent_put(&fatent, FAT_ENT_EOF); 470 if (prev_ent.nr_bhs) 471 ops->ent_put(&prev_ent, entry); 472 473 fat_collect_bhs(bhs, &nr_bhs, &fatent); 474 475 sbi->prev_free = entry; 476 if (sbi->free_clusters != -1) 477 sbi->free_clusters--; 478 sb->s_dirt = 1; 479 480 cluster[idx_clus] = entry; 481 idx_clus++; 482 if (idx_clus == nr_cluster) 483 goto out; 484 485 /* 486 * fat_collect_bhs() gets ref-count of bhs, 487 * so we can still use the prev_ent. 488 */ 489 prev_ent = fatent; 490 } 491 count++; 492 if (count == sbi->max_cluster) 493 break; 494 } while (fat_ent_next(sbi, &fatent)); 495 } 496 497 /* Couldn't allocate the free entries */ 498 sbi->free_clusters = 0; 499 sb->s_dirt = 1; 500 err = -ENOSPC; 501 502out: 503 unlock_fat(sbi); 504 fatent_brelse(&fatent); 505 if (!err) { 506 if (inode_needs_sync(inode)) 507 err = fat_sync_bhs(bhs, nr_bhs); 508 if (!err) 509 err = fat_mirror_bhs(sb, bhs, nr_bhs); 510 } 511 for (i = 0; i < nr_bhs; i++) 512 brelse(bhs[i]); 513 514 if (err && idx_clus) 515 fat_free_clusters(inode, cluster[0]); 516 517 return err; 518} 519 520int fat_free_clusters(struct inode *inode, int cluster) 521{ 522 struct super_block *sb = inode->i_sb; 523 struct msdos_sb_info *sbi = MSDOS_SB(sb); 524 struct fatent_operations *ops = sbi->fatent_ops; 525 struct fat_entry fatent; 526 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 527 int i, err, nr_bhs; 528 529 nr_bhs = 0; 530 fatent_init(&fatent); 531 lock_fat(sbi); 532 do { 533 cluster = fat_ent_read(inode, &fatent, cluster); 534 if (cluster < 0) { 535 err = cluster; 536 goto error; 537 } else if (cluster == FAT_ENT_FREE) { 538 fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF", 539 __FUNCTION__); 540 err = -EIO; 541 goto error; 542 } 543 544 ops->ent_put(&fatent, FAT_ENT_FREE); 545 if (sbi->free_clusters != -1) { 546 sbi->free_clusters++; 547 sb->s_dirt = 1; 548 } 549 550 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 551 if (sb->s_flags & MS_SYNCHRONOUS) { 552 err = fat_sync_bhs(bhs, nr_bhs); 553 if (err) 554 goto error; 555 } 556 err = fat_mirror_bhs(sb, bhs, nr_bhs); 557 if (err) 558 goto error; 559 for (i = 0; i < nr_bhs; i++) 560 brelse(bhs[i]); 561 nr_bhs = 0; 562 } 563 fat_collect_bhs(bhs, &nr_bhs, &fatent); 564 } while (cluster != FAT_ENT_EOF); 565 566 if (sb->s_flags & MS_SYNCHRONOUS) { 567 err = fat_sync_bhs(bhs, nr_bhs); 568 if (err) 569 goto error; 570 } 571 err = fat_mirror_bhs(sb, bhs, nr_bhs); 572error: 573 fatent_brelse(&fatent); 574 for (i = 0; i < nr_bhs; i++) 575 brelse(bhs[i]); 576 unlock_fat(sbi); 577 578 fat_clusters_flush(sb); 579 580 return err; 581} 582 583EXPORT_SYMBOL_GPL(fat_free_clusters); 584 585int fat_count_free_clusters(struct super_block *sb) 586{ 587 struct msdos_sb_info *sbi = MSDOS_SB(sb); 588 struct fatent_operations *ops = sbi->fatent_ops; 589 struct fat_entry fatent; 590 int err = 0, free; 591 592 lock_fat(sbi); 593 if (sbi->free_clusters != -1) 594 goto out; 595 596 free = 0; 597 fatent_init(&fatent); 598 fatent_set_entry(&fatent, FAT_START_ENT); 599 while (fatent.entry < sbi->max_cluster) { 600 err = fat_ent_read_block(sb, &fatent); 601 if (err) 602 goto out; 603 604 do { 605 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 606 free++; 607 } while (fat_ent_next(sbi, &fatent)); 608 } 609 sbi->free_clusters = free; 610 sb->s_dirt = 1; 611 fatent_brelse(&fatent); 612out: 613 unlock_fat(sbi); 614 return err; 615} 616