1 /* 2 * Copyright (C) 2004, OGAWA Hirofumi 3 * Released under GPL v2. 4 */ 5 6 #include <linux/blkdev.h> 7 #include <linux/sched/signal.h> 8 #include "fat.h" 9 10 struct 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 20 static DEFINE_SPINLOCK(fat12_entry_lock); 21 22 static void fat12_ent_blocknr(struct super_block *sb, int entry, 23 int *offset, sector_t *blocknr) 24 { 25 struct msdos_sb_info *sbi = MSDOS_SB(sb); 26 int bytes = entry + (entry >> 1); 27 WARN_ON(!fat_valid_entry(sbi, entry)); 28 *offset = bytes & (sb->s_blocksize - 1); 29 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 30 } 31 32 static void fat_ent_blocknr(struct super_block *sb, int entry, 33 int *offset, sector_t *blocknr) 34 { 35 struct msdos_sb_info *sbi = MSDOS_SB(sb); 36 int bytes = (entry << sbi->fatent_shift); 37 WARN_ON(!fat_valid_entry(sbi, entry)); 38 *offset = bytes & (sb->s_blocksize - 1); 39 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 40 } 41 42 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset) 43 { 44 struct buffer_head **bhs = fatent->bhs; 45 if (fatent->nr_bhs == 1) { 46 WARN_ON(offset >= (bhs[0]->b_size - 1)); 47 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 48 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1); 49 } else { 50 WARN_ON(offset != (bhs[0]->b_size - 1)); 51 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 52 fatent->u.ent12_p[1] = bhs[1]->b_data; 53 } 54 } 55 56 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset) 57 { 58 WARN_ON(offset & (2 - 1)); 59 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset); 60 } 61 62 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset) 63 { 64 WARN_ON(offset & (4 - 1)); 65 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset); 66 } 67 68 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent, 69 int offset, sector_t blocknr) 70 { 71 struct buffer_head **bhs = fatent->bhs; 72 73 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 74 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 75 76 bhs[0] = sb_bread(sb, blocknr); 77 if (!bhs[0]) 78 goto err; 79 80 if ((offset + 1) < sb->s_blocksize) 81 fatent->nr_bhs = 1; 82 else { 83 /* This entry is block boundary, it needs the next block */ 84 blocknr++; 85 bhs[1] = sb_bread(sb, blocknr); 86 if (!bhs[1]) 87 goto err_brelse; 88 fatent->nr_bhs = 2; 89 } 90 fat12_ent_set_ptr(fatent, offset); 91 return 0; 92 93 err_brelse: 94 brelse(bhs[0]); 95 err: 96 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr); 97 return -EIO; 98 } 99 100 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent, 101 int offset, sector_t blocknr) 102 { 103 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 104 105 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 106 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 107 fatent->bhs[0] = sb_bread(sb, blocknr); 108 if (!fatent->bhs[0]) { 109 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", 110 (llu)blocknr); 111 return -EIO; 112 } 113 fatent->nr_bhs = 1; 114 ops->ent_set_ptr(fatent, offset); 115 return 0; 116 } 117 118 static int fat12_ent_get(struct fat_entry *fatent) 119 { 120 u8 **ent12_p = fatent->u.ent12_p; 121 int next; 122 123 spin_lock(&fat12_entry_lock); 124 if (fatent->entry & 1) 125 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4); 126 else 127 next = (*ent12_p[1] << 8) | *ent12_p[0]; 128 spin_unlock(&fat12_entry_lock); 129 130 next &= 0x0fff; 131 if (next >= BAD_FAT12) 132 next = FAT_ENT_EOF; 133 return next; 134 } 135 136 static int fat16_ent_get(struct fat_entry *fatent) 137 { 138 int next = le16_to_cpu(*fatent->u.ent16_p); 139 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1)); 140 if (next >= BAD_FAT16) 141 next = FAT_ENT_EOF; 142 return next; 143 } 144 145 static int fat32_ent_get(struct fat_entry *fatent) 146 { 147 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff; 148 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1)); 149 if (next >= BAD_FAT32) 150 next = FAT_ENT_EOF; 151 return next; 152 } 153 154 static void fat12_ent_put(struct fat_entry *fatent, int new) 155 { 156 u8 **ent12_p = fatent->u.ent12_p; 157 158 if (new == FAT_ENT_EOF) 159 new = EOF_FAT12; 160 161 spin_lock(&fat12_entry_lock); 162 if (fatent->entry & 1) { 163 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f); 164 *ent12_p[1] = new >> 4; 165 } else { 166 *ent12_p[0] = new & 0xff; 167 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8); 168 } 169 spin_unlock(&fat12_entry_lock); 170 171 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 172 if (fatent->nr_bhs == 2) 173 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode); 174 } 175 176 static void fat16_ent_put(struct fat_entry *fatent, int new) 177 { 178 if (new == FAT_ENT_EOF) 179 new = EOF_FAT16; 180 181 *fatent->u.ent16_p = cpu_to_le16(new); 182 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 183 } 184 185 static void fat32_ent_put(struct fat_entry *fatent, int new) 186 { 187 WARN_ON(new & 0xf0000000); 188 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; 189 *fatent->u.ent32_p = cpu_to_le32(new); 190 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 191 } 192 193 static int fat12_ent_next(struct fat_entry *fatent) 194 { 195 u8 **ent12_p = fatent->u.ent12_p; 196 struct buffer_head **bhs = fatent->bhs; 197 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); 198 199 fatent->entry++; 200 if (fatent->nr_bhs == 1) { 201 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + 202 (bhs[0]->b_size - 2))); 203 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + 204 (bhs[0]->b_size - 1))); 205 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { 206 ent12_p[0] = nextp - 1; 207 ent12_p[1] = nextp; 208 return 1; 209 } 210 } else { 211 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + 212 (bhs[0]->b_size - 1))); 213 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); 214 ent12_p[0] = nextp - 1; 215 ent12_p[1] = nextp; 216 brelse(bhs[0]); 217 bhs[0] = bhs[1]; 218 fatent->nr_bhs = 1; 219 return 1; 220 } 221 ent12_p[0] = NULL; 222 ent12_p[1] = NULL; 223 return 0; 224 } 225 226 static int fat16_ent_next(struct fat_entry *fatent) 227 { 228 const struct buffer_head *bh = fatent->bhs[0]; 229 fatent->entry++; 230 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { 231 fatent->u.ent16_p++; 232 return 1; 233 } 234 fatent->u.ent16_p = NULL; 235 return 0; 236 } 237 238 static int fat32_ent_next(struct fat_entry *fatent) 239 { 240 const struct buffer_head *bh = fatent->bhs[0]; 241 fatent->entry++; 242 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { 243 fatent->u.ent32_p++; 244 return 1; 245 } 246 fatent->u.ent32_p = NULL; 247 return 0; 248 } 249 250 static const struct fatent_operations fat12_ops = { 251 .ent_blocknr = fat12_ent_blocknr, 252 .ent_set_ptr = fat12_ent_set_ptr, 253 .ent_bread = fat12_ent_bread, 254 .ent_get = fat12_ent_get, 255 .ent_put = fat12_ent_put, 256 .ent_next = fat12_ent_next, 257 }; 258 259 static const struct fatent_operations fat16_ops = { 260 .ent_blocknr = fat_ent_blocknr, 261 .ent_set_ptr = fat16_ent_set_ptr, 262 .ent_bread = fat_ent_bread, 263 .ent_get = fat16_ent_get, 264 .ent_put = fat16_ent_put, 265 .ent_next = fat16_ent_next, 266 }; 267 268 static const struct fatent_operations fat32_ops = { 269 .ent_blocknr = fat_ent_blocknr, 270 .ent_set_ptr = fat32_ent_set_ptr, 271 .ent_bread = fat_ent_bread, 272 .ent_get = fat32_ent_get, 273 .ent_put = fat32_ent_put, 274 .ent_next = fat32_ent_next, 275 }; 276 277 static inline void lock_fat(struct msdos_sb_info *sbi) 278 { 279 mutex_lock(&sbi->fat_lock); 280 } 281 282 static inline void unlock_fat(struct msdos_sb_info *sbi) 283 { 284 mutex_unlock(&sbi->fat_lock); 285 } 286 287 void fat_ent_access_init(struct super_block *sb) 288 { 289 struct msdos_sb_info *sbi = MSDOS_SB(sb); 290 291 mutex_init(&sbi->fat_lock); 292 293 if (is_fat32(sbi)) { 294 sbi->fatent_shift = 2; 295 sbi->fatent_ops = &fat32_ops; 296 } else if (is_fat16(sbi)) { 297 sbi->fatent_shift = 1; 298 sbi->fatent_ops = &fat16_ops; 299 } else if (is_fat12(sbi)) { 300 sbi->fatent_shift = -1; 301 sbi->fatent_ops = &fat12_ops; 302 } else { 303 fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits); 304 } 305 } 306 307 static void mark_fsinfo_dirty(struct super_block *sb) 308 { 309 struct msdos_sb_info *sbi = MSDOS_SB(sb); 310 311 if (sb_rdonly(sb) || !is_fat32(sbi)) 312 return; 313 314 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); 315 } 316 317 static inline int fat_ent_update_ptr(struct super_block *sb, 318 struct fat_entry *fatent, 319 int offset, sector_t blocknr) 320 { 321 struct msdos_sb_info *sbi = MSDOS_SB(sb); 322 const struct fatent_operations *ops = sbi->fatent_ops; 323 struct buffer_head **bhs = fatent->bhs; 324 325 /* Is this fatent's blocks including this entry? */ 326 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 327 return 0; 328 if (is_fat12(sbi)) { 329 if ((offset + 1) < sb->s_blocksize) { 330 /* This entry is on bhs[0]. */ 331 if (fatent->nr_bhs == 2) { 332 brelse(bhs[1]); 333 fatent->nr_bhs = 1; 334 } 335 } else { 336 /* This entry needs the next block. */ 337 if (fatent->nr_bhs != 2) 338 return 0; 339 if (bhs[1]->b_blocknr != (blocknr + 1)) 340 return 0; 341 } 342 } 343 ops->ent_set_ptr(fatent, offset); 344 return 1; 345 } 346 347 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 348 { 349 struct super_block *sb = inode->i_sb; 350 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 351 const struct fatent_operations *ops = sbi->fatent_ops; 352 int err, offset; 353 sector_t blocknr; 354 355 if (!fat_valid_entry(sbi, entry)) { 356 fatent_brelse(fatent); 357 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); 358 return -EIO; 359 } 360 361 fatent_set_entry(fatent, entry); 362 ops->ent_blocknr(sb, entry, &offset, &blocknr); 363 364 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 365 fatent_brelse(fatent); 366 err = ops->ent_bread(sb, fatent, offset, blocknr); 367 if (err) 368 return err; 369 } 370 return ops->ent_get(fatent); 371 } 372 373 /* FIXME: We can write the blocks as more big chunk. */ 374 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 375 int nr_bhs) 376 { 377 struct msdos_sb_info *sbi = MSDOS_SB(sb); 378 struct buffer_head *c_bh; 379 int err, n, copy; 380 381 err = 0; 382 for (copy = 1; copy < sbi->fats; copy++) { 383 sector_t backup_fat = sbi->fat_length * copy; 384 385 for (n = 0; n < nr_bhs; n++) { 386 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 387 if (!c_bh) { 388 err = -ENOMEM; 389 goto error; 390 } 391 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 392 set_buffer_uptodate(c_bh); 393 mark_buffer_dirty_inode(c_bh, sbi->fat_inode); 394 if (sb->s_flags & SB_SYNCHRONOUS) 395 err = sync_dirty_buffer(c_bh); 396 brelse(c_bh); 397 if (err) 398 goto error; 399 } 400 } 401 error: 402 return err; 403 } 404 405 int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 406 int new, int wait) 407 { 408 struct super_block *sb = inode->i_sb; 409 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 410 int err; 411 412 ops->ent_put(fatent, new); 413 if (wait) { 414 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 415 if (err) 416 return err; 417 } 418 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 419 } 420 421 static inline int fat_ent_next(struct msdos_sb_info *sbi, 422 struct fat_entry *fatent) 423 { 424 if (sbi->fatent_ops->ent_next(fatent)) { 425 if (fatent->entry < sbi->max_cluster) 426 return 1; 427 } 428 return 0; 429 } 430 431 static inline int fat_ent_read_block(struct super_block *sb, 432 struct fat_entry *fatent) 433 { 434 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 435 sector_t blocknr; 436 int offset; 437 438 fatent_brelse(fatent); 439 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 440 return ops->ent_bread(sb, fatent, offset, blocknr); 441 } 442 443 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 444 struct fat_entry *fatent) 445 { 446 int n, i; 447 448 for (n = 0; n < fatent->nr_bhs; n++) { 449 for (i = 0; i < *nr_bhs; i++) { 450 if (fatent->bhs[n] == bhs[i]) 451 break; 452 } 453 if (i == *nr_bhs) { 454 get_bh(fatent->bhs[n]); 455 bhs[i] = fatent->bhs[n]; 456 (*nr_bhs)++; 457 } 458 } 459 } 460 461 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 462 { 463 struct super_block *sb = inode->i_sb; 464 struct msdos_sb_info *sbi = MSDOS_SB(sb); 465 const struct fatent_operations *ops = sbi->fatent_ops; 466 struct fat_entry fatent, prev_ent; 467 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 468 int i, count, err, nr_bhs, idx_clus; 469 470 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 471 472 lock_fat(sbi); 473 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 474 sbi->free_clusters < nr_cluster) { 475 unlock_fat(sbi); 476 return -ENOSPC; 477 } 478 479 err = nr_bhs = idx_clus = 0; 480 count = FAT_START_ENT; 481 fatent_init(&prev_ent); 482 fatent_init(&fatent); 483 fatent_set_entry(&fatent, sbi->prev_free + 1); 484 while (count < sbi->max_cluster) { 485 if (fatent.entry >= sbi->max_cluster) 486 fatent.entry = FAT_START_ENT; 487 fatent_set_entry(&fatent, fatent.entry); 488 err = fat_ent_read_block(sb, &fatent); 489 if (err) 490 goto out; 491 492 /* Find the free entries in a block */ 493 do { 494 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 495 int entry = fatent.entry; 496 497 /* make the cluster chain */ 498 ops->ent_put(&fatent, FAT_ENT_EOF); 499 if (prev_ent.nr_bhs) 500 ops->ent_put(&prev_ent, entry); 501 502 fat_collect_bhs(bhs, &nr_bhs, &fatent); 503 504 sbi->prev_free = entry; 505 if (sbi->free_clusters != -1) 506 sbi->free_clusters--; 507 508 cluster[idx_clus] = entry; 509 idx_clus++; 510 if (idx_clus == nr_cluster) 511 goto out; 512 513 /* 514 * fat_collect_bhs() gets ref-count of bhs, 515 * so we can still use the prev_ent. 516 */ 517 prev_ent = fatent; 518 } 519 count++; 520 if (count == sbi->max_cluster) 521 break; 522 } while (fat_ent_next(sbi, &fatent)); 523 } 524 525 /* Couldn't allocate the free entries */ 526 sbi->free_clusters = 0; 527 sbi->free_clus_valid = 1; 528 err = -ENOSPC; 529 530 out: 531 unlock_fat(sbi); 532 mark_fsinfo_dirty(sb); 533 fatent_brelse(&fatent); 534 if (!err) { 535 if (inode_needs_sync(inode)) 536 err = fat_sync_bhs(bhs, nr_bhs); 537 if (!err) 538 err = fat_mirror_bhs(sb, bhs, nr_bhs); 539 } 540 for (i = 0; i < nr_bhs; i++) 541 brelse(bhs[i]); 542 543 if (err && idx_clus) 544 fat_free_clusters(inode, cluster[0]); 545 546 return err; 547 } 548 549 int fat_free_clusters(struct inode *inode, int cluster) 550 { 551 struct super_block *sb = inode->i_sb; 552 struct msdos_sb_info *sbi = MSDOS_SB(sb); 553 const struct fatent_operations *ops = sbi->fatent_ops; 554 struct fat_entry fatent; 555 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 556 int i, err, nr_bhs; 557 int first_cl = cluster, dirty_fsinfo = 0; 558 559 nr_bhs = 0; 560 fatent_init(&fatent); 561 lock_fat(sbi); 562 do { 563 cluster = fat_ent_read(inode, &fatent, cluster); 564 if (cluster < 0) { 565 err = cluster; 566 goto error; 567 } else if (cluster == FAT_ENT_FREE) { 568 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", 569 __func__); 570 err = -EIO; 571 goto error; 572 } 573 574 if (sbi->options.discard) { 575 /* 576 * Issue discard for the sectors we no longer 577 * care about, batching contiguous clusters 578 * into one request 579 */ 580 if (cluster != fatent.entry + 1) { 581 int nr_clus = fatent.entry - first_cl + 1; 582 583 sb_issue_discard(sb, 584 fat_clus_to_blknr(sbi, first_cl), 585 nr_clus * sbi->sec_per_clus, 586 GFP_NOFS, 0); 587 588 first_cl = cluster; 589 } 590 } 591 592 ops->ent_put(&fatent, FAT_ENT_FREE); 593 if (sbi->free_clusters != -1) { 594 sbi->free_clusters++; 595 dirty_fsinfo = 1; 596 } 597 598 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 599 if (sb->s_flags & SB_SYNCHRONOUS) { 600 err = fat_sync_bhs(bhs, nr_bhs); 601 if (err) 602 goto error; 603 } 604 err = fat_mirror_bhs(sb, bhs, nr_bhs); 605 if (err) 606 goto error; 607 for (i = 0; i < nr_bhs; i++) 608 brelse(bhs[i]); 609 nr_bhs = 0; 610 } 611 fat_collect_bhs(bhs, &nr_bhs, &fatent); 612 } while (cluster != FAT_ENT_EOF); 613 614 if (sb->s_flags & SB_SYNCHRONOUS) { 615 err = fat_sync_bhs(bhs, nr_bhs); 616 if (err) 617 goto error; 618 } 619 err = fat_mirror_bhs(sb, bhs, nr_bhs); 620 error: 621 fatent_brelse(&fatent); 622 for (i = 0; i < nr_bhs; i++) 623 brelse(bhs[i]); 624 unlock_fat(sbi); 625 if (dirty_fsinfo) 626 mark_fsinfo_dirty(sb); 627 628 return err; 629 } 630 EXPORT_SYMBOL_GPL(fat_free_clusters); 631 632 /* 128kb is the whole sectors for FAT12 and FAT16 */ 633 #define FAT_READA_SIZE (128 * 1024) 634 635 static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent, 636 unsigned long reada_blocks) 637 { 638 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 639 sector_t blocknr; 640 int i, offset; 641 642 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 643 644 for (i = 0; i < reada_blocks; i++) 645 sb_breadahead(sb, blocknr + i); 646 } 647 648 int fat_count_free_clusters(struct super_block *sb) 649 { 650 struct msdos_sb_info *sbi = MSDOS_SB(sb); 651 const struct fatent_operations *ops = sbi->fatent_ops; 652 struct fat_entry fatent; 653 unsigned long reada_blocks, reada_mask, cur_block; 654 int err = 0, free; 655 656 lock_fat(sbi); 657 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 658 goto out; 659 660 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; 661 reada_mask = reada_blocks - 1; 662 cur_block = 0; 663 664 free = 0; 665 fatent_init(&fatent); 666 fatent_set_entry(&fatent, FAT_START_ENT); 667 while (fatent.entry < sbi->max_cluster) { 668 /* readahead of fat blocks */ 669 if ((cur_block & reada_mask) == 0) { 670 unsigned long rest = sbi->fat_length - cur_block; 671 fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); 672 } 673 cur_block++; 674 675 err = fat_ent_read_block(sb, &fatent); 676 if (err) 677 goto out; 678 679 do { 680 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 681 free++; 682 } while (fat_ent_next(sbi, &fatent)); 683 cond_resched(); 684 } 685 sbi->free_clusters = free; 686 sbi->free_clus_valid = 1; 687 mark_fsinfo_dirty(sb); 688 fatent_brelse(&fatent); 689 out: 690 unlock_fat(sbi); 691 return err; 692 } 693 694 static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus) 695 { 696 struct msdos_sb_info *sbi = MSDOS_SB(sb); 697 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus), 698 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0); 699 } 700 701 int fat_trim_fs(struct inode *inode, struct fstrim_range *range) 702 { 703 struct super_block *sb = inode->i_sb; 704 struct msdos_sb_info *sbi = MSDOS_SB(sb); 705 const struct fatent_operations *ops = sbi->fatent_ops; 706 struct fat_entry fatent; 707 u64 ent_start, ent_end, minlen, trimmed = 0; 708 u32 free = 0; 709 unsigned long reada_blocks, reada_mask, cur_block = 0; 710 int err = 0; 711 712 /* 713 * FAT data is organized as clusters, trim at the granulary of cluster. 714 * 715 * fstrim_range is in byte, convert vaules to cluster index. 716 * Treat sectors before data region as all used, not to trim them. 717 */ 718 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT); 719 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1; 720 minlen = range->minlen >> sbi->cluster_bits; 721 722 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size) 723 return -EINVAL; 724 if (ent_end >= sbi->max_cluster) 725 ent_end = sbi->max_cluster - 1; 726 727 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; 728 reada_mask = reada_blocks - 1; 729 730 fatent_init(&fatent); 731 lock_fat(sbi); 732 fatent_set_entry(&fatent, ent_start); 733 while (fatent.entry <= ent_end) { 734 /* readahead of fat blocks */ 735 if ((cur_block & reada_mask) == 0) { 736 unsigned long rest = sbi->fat_length - cur_block; 737 fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); 738 } 739 cur_block++; 740 741 err = fat_ent_read_block(sb, &fatent); 742 if (err) 743 goto error; 744 do { 745 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 746 free++; 747 } else if (free) { 748 if (free >= minlen) { 749 u32 clus = fatent.entry - free; 750 751 err = fat_trim_clusters(sb, clus, free); 752 if (err && err != -EOPNOTSUPP) 753 goto error; 754 if (!err) 755 trimmed += free; 756 err = 0; 757 } 758 free = 0; 759 } 760 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end); 761 762 if (fatal_signal_pending(current)) { 763 err = -ERESTARTSYS; 764 goto error; 765 } 766 767 if (need_resched()) { 768 fatent_brelse(&fatent); 769 unlock_fat(sbi); 770 cond_resched(); 771 lock_fat(sbi); 772 } 773 } 774 /* handle scenario when tail entries are all free */ 775 if (free && free >= minlen) { 776 u32 clus = fatent.entry - free; 777 778 err = fat_trim_clusters(sb, clus, free); 779 if (err && err != -EOPNOTSUPP) 780 goto error; 781 if (!err) 782 trimmed += free; 783 err = 0; 784 } 785 786 error: 787 fatent_brelse(&fatent); 788 unlock_fat(sbi); 789 790 range->len = trimmed << sbi->cluster_bits; 791 792 return err; 793 } 794