1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2004, OGAWA Hirofumi 4 */ 5 6 #include <linux/blkdev.h> 7 #include <linux/sched/signal.h> 8 #include <linux/backing-dev-defs.h> 9 #include "fat.h" 10 11 struct fatent_operations { 12 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *); 13 void (*ent_set_ptr)(struct fat_entry *, int); 14 int (*ent_bread)(struct super_block *, struct fat_entry *, 15 int, sector_t); 16 int (*ent_get)(struct fat_entry *); 17 void (*ent_put)(struct fat_entry *, int); 18 int (*ent_next)(struct fat_entry *); 19 }; 20 21 static DEFINE_SPINLOCK(fat12_entry_lock); 22 23 static void fat12_ent_blocknr(struct super_block *sb, int entry, 24 int *offset, sector_t *blocknr) 25 { 26 struct msdos_sb_info *sbi = MSDOS_SB(sb); 27 int bytes = entry + (entry >> 1); 28 WARN_ON(!fat_valid_entry(sbi, entry)); 29 *offset = bytes & (sb->s_blocksize - 1); 30 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 31 } 32 33 static void fat_ent_blocknr(struct super_block *sb, int entry, 34 int *offset, sector_t *blocknr) 35 { 36 struct msdos_sb_info *sbi = MSDOS_SB(sb); 37 int bytes = (entry << sbi->fatent_shift); 38 WARN_ON(!fat_valid_entry(sbi, entry)); 39 *offset = bytes & (sb->s_blocksize - 1); 40 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 41 } 42 43 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset) 44 { 45 struct buffer_head **bhs = fatent->bhs; 46 if (fatent->nr_bhs == 1) { 47 WARN_ON(offset >= (bhs[0]->b_size - 1)); 48 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 49 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1); 50 } else { 51 WARN_ON(offset != (bhs[0]->b_size - 1)); 52 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 53 fatent->u.ent12_p[1] = bhs[1]->b_data; 54 } 55 } 56 57 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset) 58 { 59 WARN_ON(offset & (2 - 1)); 60 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset); 61 } 62 63 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset) 64 { 65 WARN_ON(offset & (4 - 1)); 66 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset); 67 } 68 69 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent, 70 int offset, sector_t blocknr) 71 { 72 struct buffer_head **bhs = fatent->bhs; 73 74 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 75 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 76 77 bhs[0] = sb_bread(sb, blocknr); 78 if (!bhs[0]) 79 goto err; 80 81 if ((offset + 1) < sb->s_blocksize) 82 fatent->nr_bhs = 1; 83 else { 84 /* This entry is block boundary, it needs the next block */ 85 blocknr++; 86 bhs[1] = sb_bread(sb, blocknr); 87 if (!bhs[1]) 88 goto err_brelse; 89 fatent->nr_bhs = 2; 90 } 91 fat12_ent_set_ptr(fatent, offset); 92 return 0; 93 94 err_brelse: 95 brelse(bhs[0]); 96 err: 97 fat_msg_ratelimit(sb, KERN_ERR, "FAT read failed (blocknr %llu)", 98 (llu)blocknr); 99 return -EIO; 100 } 101 102 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent, 103 int offset, sector_t blocknr) 104 { 105 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 106 107 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 108 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 109 fatent->bhs[0] = sb_bread(sb, blocknr); 110 if (!fatent->bhs[0]) { 111 fat_msg_ratelimit(sb, KERN_ERR, "FAT read failed (blocknr %llu)", 112 (llu)blocknr); 113 return -EIO; 114 } 115 fatent->nr_bhs = 1; 116 ops->ent_set_ptr(fatent, offset); 117 return 0; 118 } 119 120 static int fat12_ent_get(struct fat_entry *fatent) 121 { 122 u8 **ent12_p = fatent->u.ent12_p; 123 int next; 124 125 spin_lock(&fat12_entry_lock); 126 if (fatent->entry & 1) 127 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4); 128 else 129 next = (*ent12_p[1] << 8) | *ent12_p[0]; 130 spin_unlock(&fat12_entry_lock); 131 132 next &= 0x0fff; 133 if (next >= BAD_FAT12) 134 next = FAT_ENT_EOF; 135 return next; 136 } 137 138 static int fat16_ent_get(struct fat_entry *fatent) 139 { 140 int next = le16_to_cpu(*fatent->u.ent16_p); 141 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1)); 142 if (next >= BAD_FAT16) 143 next = FAT_ENT_EOF; 144 return next; 145 } 146 147 static int fat32_ent_get(struct fat_entry *fatent) 148 { 149 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff; 150 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1)); 151 if (next >= BAD_FAT32) 152 next = FAT_ENT_EOF; 153 return next; 154 } 155 156 static void fat12_ent_put(struct fat_entry *fatent, int new) 157 { 158 u8 **ent12_p = fatent->u.ent12_p; 159 160 if (new == FAT_ENT_EOF) 161 new = EOF_FAT12; 162 163 spin_lock(&fat12_entry_lock); 164 if (fatent->entry & 1) { 165 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f); 166 *ent12_p[1] = new >> 4; 167 } else { 168 *ent12_p[0] = new & 0xff; 169 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8); 170 } 171 spin_unlock(&fat12_entry_lock); 172 173 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 174 if (fatent->nr_bhs == 2) 175 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode); 176 } 177 178 static void fat16_ent_put(struct fat_entry *fatent, int new) 179 { 180 if (new == FAT_ENT_EOF) 181 new = EOF_FAT16; 182 183 *fatent->u.ent16_p = cpu_to_le16(new); 184 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 185 } 186 187 static void fat32_ent_put(struct fat_entry *fatent, int new) 188 { 189 WARN_ON(new & 0xf0000000); 190 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; 191 *fatent->u.ent32_p = cpu_to_le32(new); 192 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 193 } 194 195 static int fat12_ent_next(struct fat_entry *fatent) 196 { 197 u8 **ent12_p = fatent->u.ent12_p; 198 struct buffer_head **bhs = fatent->bhs; 199 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); 200 201 fatent->entry++; 202 if (fatent->nr_bhs == 1) { 203 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + 204 (bhs[0]->b_size - 2))); 205 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + 206 (bhs[0]->b_size - 1))); 207 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { 208 ent12_p[0] = nextp - 1; 209 ent12_p[1] = nextp; 210 return 1; 211 } 212 } else { 213 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + 214 (bhs[0]->b_size - 1))); 215 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); 216 ent12_p[0] = nextp - 1; 217 ent12_p[1] = nextp; 218 brelse(bhs[0]); 219 bhs[0] = bhs[1]; 220 fatent->nr_bhs = 1; 221 return 1; 222 } 223 ent12_p[0] = NULL; 224 ent12_p[1] = NULL; 225 return 0; 226 } 227 228 static int fat16_ent_next(struct fat_entry *fatent) 229 { 230 const struct buffer_head *bh = fatent->bhs[0]; 231 fatent->entry++; 232 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { 233 fatent->u.ent16_p++; 234 return 1; 235 } 236 fatent->u.ent16_p = NULL; 237 return 0; 238 } 239 240 static int fat32_ent_next(struct fat_entry *fatent) 241 { 242 const struct buffer_head *bh = fatent->bhs[0]; 243 fatent->entry++; 244 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { 245 fatent->u.ent32_p++; 246 return 1; 247 } 248 fatent->u.ent32_p = NULL; 249 return 0; 250 } 251 252 static const struct fatent_operations fat12_ops = { 253 .ent_blocknr = fat12_ent_blocknr, 254 .ent_set_ptr = fat12_ent_set_ptr, 255 .ent_bread = fat12_ent_bread, 256 .ent_get = fat12_ent_get, 257 .ent_put = fat12_ent_put, 258 .ent_next = fat12_ent_next, 259 }; 260 261 static const struct fatent_operations fat16_ops = { 262 .ent_blocknr = fat_ent_blocknr, 263 .ent_set_ptr = fat16_ent_set_ptr, 264 .ent_bread = fat_ent_bread, 265 .ent_get = fat16_ent_get, 266 .ent_put = fat16_ent_put, 267 .ent_next = fat16_ent_next, 268 }; 269 270 static const struct fatent_operations fat32_ops = { 271 .ent_blocknr = fat_ent_blocknr, 272 .ent_set_ptr = fat32_ent_set_ptr, 273 .ent_bread = fat_ent_bread, 274 .ent_get = fat32_ent_get, 275 .ent_put = fat32_ent_put, 276 .ent_next = fat32_ent_next, 277 }; 278 279 static inline void lock_fat(struct msdos_sb_info *sbi) 280 { 281 mutex_lock(&sbi->fat_lock); 282 } 283 284 static inline void unlock_fat(struct msdos_sb_info *sbi) 285 { 286 mutex_unlock(&sbi->fat_lock); 287 } 288 289 void fat_ent_access_init(struct super_block *sb) 290 { 291 struct msdos_sb_info *sbi = MSDOS_SB(sb); 292 293 mutex_init(&sbi->fat_lock); 294 295 if (is_fat32(sbi)) { 296 sbi->fatent_shift = 2; 297 sbi->fatent_ops = &fat32_ops; 298 } else if (is_fat16(sbi)) { 299 sbi->fatent_shift = 1; 300 sbi->fatent_ops = &fat16_ops; 301 } else if (is_fat12(sbi)) { 302 sbi->fatent_shift = -1; 303 sbi->fatent_ops = &fat12_ops; 304 } else { 305 fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits); 306 } 307 } 308 309 static void mark_fsinfo_dirty(struct super_block *sb) 310 { 311 struct msdos_sb_info *sbi = MSDOS_SB(sb); 312 313 if (sb_rdonly(sb) || !is_fat32(sbi)) 314 return; 315 316 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); 317 } 318 319 static inline int fat_ent_update_ptr(struct super_block *sb, 320 struct fat_entry *fatent, 321 int offset, sector_t blocknr) 322 { 323 struct msdos_sb_info *sbi = MSDOS_SB(sb); 324 const struct fatent_operations *ops = sbi->fatent_ops; 325 struct buffer_head **bhs = fatent->bhs; 326 327 /* Is this fatent's blocks including this entry? */ 328 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 329 return 0; 330 if (is_fat12(sbi)) { 331 if ((offset + 1) < sb->s_blocksize) { 332 /* This entry is on bhs[0]. */ 333 if (fatent->nr_bhs == 2) { 334 brelse(bhs[1]); 335 fatent->nr_bhs = 1; 336 } 337 } else { 338 /* This entry needs the next block. */ 339 if (fatent->nr_bhs != 2) 340 return 0; 341 if (bhs[1]->b_blocknr != (blocknr + 1)) 342 return 0; 343 } 344 } 345 ops->ent_set_ptr(fatent, offset); 346 return 1; 347 } 348 349 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 350 { 351 struct super_block *sb = inode->i_sb; 352 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 353 const struct fatent_operations *ops = sbi->fatent_ops; 354 int err, offset; 355 sector_t blocknr; 356 357 if (!fat_valid_entry(sbi, entry)) { 358 fatent_brelse(fatent); 359 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); 360 return -EIO; 361 } 362 363 fatent_set_entry(fatent, entry); 364 ops->ent_blocknr(sb, entry, &offset, &blocknr); 365 366 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 367 fatent_brelse(fatent); 368 err = ops->ent_bread(sb, fatent, offset, blocknr); 369 if (err) 370 return err; 371 } 372 return ops->ent_get(fatent); 373 } 374 375 /* FIXME: We can write the blocks as more big chunk. */ 376 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 377 int nr_bhs) 378 { 379 struct msdos_sb_info *sbi = MSDOS_SB(sb); 380 struct buffer_head *c_bh; 381 int err, n, copy; 382 383 err = 0; 384 for (copy = 1; copy < sbi->fats; copy++) { 385 sector_t backup_fat = sbi->fat_length * copy; 386 387 for (n = 0; n < nr_bhs; n++) { 388 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 389 if (!c_bh) { 390 err = -ENOMEM; 391 goto error; 392 } 393 /* Avoid race with userspace read via bdev */ 394 lock_buffer(c_bh); 395 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 396 set_buffer_uptodate(c_bh); 397 unlock_buffer(c_bh); 398 mark_buffer_dirty_inode(c_bh, sbi->fat_inode); 399 if (sb->s_flags & SB_SYNCHRONOUS) 400 err = sync_dirty_buffer(c_bh); 401 brelse(c_bh); 402 if (err) 403 goto error; 404 } 405 } 406 error: 407 return err; 408 } 409 410 int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 411 int new, int wait) 412 { 413 struct super_block *sb = inode->i_sb; 414 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 415 int err; 416 417 ops->ent_put(fatent, new); 418 if (wait) { 419 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 420 if (err) 421 return err; 422 } 423 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 424 } 425 426 static inline int fat_ent_next(struct msdos_sb_info *sbi, 427 struct fat_entry *fatent) 428 { 429 if (sbi->fatent_ops->ent_next(fatent)) { 430 if (fatent->entry < sbi->max_cluster) 431 return 1; 432 } 433 return 0; 434 } 435 436 static inline int fat_ent_read_block(struct super_block *sb, 437 struct fat_entry *fatent) 438 { 439 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 440 sector_t blocknr; 441 int offset; 442 443 fatent_brelse(fatent); 444 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 445 return ops->ent_bread(sb, fatent, offset, blocknr); 446 } 447 448 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 449 struct fat_entry *fatent) 450 { 451 int n, i; 452 453 for (n = 0; n < fatent->nr_bhs; n++) { 454 for (i = 0; i < *nr_bhs; i++) { 455 if (fatent->bhs[n] == bhs[i]) 456 break; 457 } 458 if (i == *nr_bhs) { 459 get_bh(fatent->bhs[n]); 460 bhs[i] = fatent->bhs[n]; 461 (*nr_bhs)++; 462 } 463 } 464 } 465 466 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 467 { 468 struct super_block *sb = inode->i_sb; 469 struct msdos_sb_info *sbi = MSDOS_SB(sb); 470 const struct fatent_operations *ops = sbi->fatent_ops; 471 struct fat_entry fatent, prev_ent; 472 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 473 int i, count, err, nr_bhs, idx_clus; 474 475 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 476 477 lock_fat(sbi); 478 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 479 sbi->free_clusters < nr_cluster) { 480 unlock_fat(sbi); 481 return -ENOSPC; 482 } 483 484 err = nr_bhs = idx_clus = 0; 485 count = FAT_START_ENT; 486 fatent_init(&prev_ent); 487 fatent_init(&fatent); 488 fatent_set_entry(&fatent, sbi->prev_free + 1); 489 while (count < sbi->max_cluster) { 490 if (fatent.entry >= sbi->max_cluster) 491 fatent.entry = FAT_START_ENT; 492 fatent_set_entry(&fatent, fatent.entry); 493 err = fat_ent_read_block(sb, &fatent); 494 if (err) 495 goto out; 496 497 /* Find the free entries in a block */ 498 do { 499 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 500 int entry = fatent.entry; 501 502 /* make the cluster chain */ 503 ops->ent_put(&fatent, FAT_ENT_EOF); 504 if (prev_ent.nr_bhs) 505 ops->ent_put(&prev_ent, entry); 506 507 fat_collect_bhs(bhs, &nr_bhs, &fatent); 508 509 sbi->prev_free = entry; 510 if (sbi->free_clusters != -1) 511 sbi->free_clusters--; 512 513 cluster[idx_clus] = entry; 514 idx_clus++; 515 if (idx_clus == nr_cluster) 516 goto out; 517 518 /* 519 * fat_collect_bhs() gets ref-count of bhs, 520 * so we can still use the prev_ent. 521 */ 522 prev_ent = fatent; 523 } 524 count++; 525 if (count == sbi->max_cluster) 526 break; 527 } while (fat_ent_next(sbi, &fatent)); 528 } 529 530 /* Couldn't allocate the free entries */ 531 sbi->free_clusters = 0; 532 sbi->free_clus_valid = 1; 533 err = -ENOSPC; 534 535 out: 536 unlock_fat(sbi); 537 mark_fsinfo_dirty(sb); 538 fatent_brelse(&fatent); 539 if (!err) { 540 if (inode_needs_sync(inode)) 541 err = fat_sync_bhs(bhs, nr_bhs); 542 if (!err) 543 err = fat_mirror_bhs(sb, bhs, nr_bhs); 544 } 545 for (i = 0; i < nr_bhs; i++) 546 brelse(bhs[i]); 547 548 if (err && idx_clus) 549 fat_free_clusters(inode, cluster[0]); 550 551 return err; 552 } 553 554 int fat_free_clusters(struct inode *inode, int cluster) 555 { 556 struct super_block *sb = inode->i_sb; 557 struct msdos_sb_info *sbi = MSDOS_SB(sb); 558 const struct fatent_operations *ops = sbi->fatent_ops; 559 struct fat_entry fatent; 560 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 561 int i, err, nr_bhs; 562 int first_cl = cluster, dirty_fsinfo = 0; 563 564 nr_bhs = 0; 565 fatent_init(&fatent); 566 lock_fat(sbi); 567 do { 568 cluster = fat_ent_read(inode, &fatent, cluster); 569 if (cluster < 0) { 570 err = cluster; 571 goto error; 572 } else if (cluster == FAT_ENT_FREE) { 573 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", 574 __func__); 575 err = -EIO; 576 goto error; 577 } 578 579 if (sbi->options.discard) { 580 /* 581 * Issue discard for the sectors we no longer 582 * care about, batching contiguous clusters 583 * into one request 584 */ 585 if (cluster != fatent.entry + 1) { 586 int nr_clus = fatent.entry - first_cl + 1; 587 588 sb_issue_discard(sb, 589 fat_clus_to_blknr(sbi, first_cl), 590 nr_clus * sbi->sec_per_clus, 591 GFP_NOFS, 0); 592 593 first_cl = cluster; 594 } 595 } 596 597 ops->ent_put(&fatent, FAT_ENT_FREE); 598 if (sbi->free_clusters != -1) { 599 sbi->free_clusters++; 600 dirty_fsinfo = 1; 601 } 602 603 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 604 if (sb->s_flags & SB_SYNCHRONOUS) { 605 err = fat_sync_bhs(bhs, nr_bhs); 606 if (err) 607 goto error; 608 } 609 err = fat_mirror_bhs(sb, bhs, nr_bhs); 610 if (err) 611 goto error; 612 for (i = 0; i < nr_bhs; i++) 613 brelse(bhs[i]); 614 nr_bhs = 0; 615 } 616 fat_collect_bhs(bhs, &nr_bhs, &fatent); 617 } while (cluster != FAT_ENT_EOF); 618 619 if (sb->s_flags & SB_SYNCHRONOUS) { 620 err = fat_sync_bhs(bhs, nr_bhs); 621 if (err) 622 goto error; 623 } 624 err = fat_mirror_bhs(sb, bhs, nr_bhs); 625 error: 626 fatent_brelse(&fatent); 627 for (i = 0; i < nr_bhs; i++) 628 brelse(bhs[i]); 629 unlock_fat(sbi); 630 if (dirty_fsinfo) 631 mark_fsinfo_dirty(sb); 632 633 return err; 634 } 635 EXPORT_SYMBOL_GPL(fat_free_clusters); 636 637 struct fatent_ra { 638 sector_t cur; 639 sector_t limit; 640 641 unsigned int ra_blocks; 642 sector_t ra_advance; 643 sector_t ra_next; 644 sector_t ra_limit; 645 }; 646 647 static void fat_ra_init(struct super_block *sb, struct fatent_ra *ra, 648 struct fat_entry *fatent, int ent_limit) 649 { 650 struct msdos_sb_info *sbi = MSDOS_SB(sb); 651 const struct fatent_operations *ops = sbi->fatent_ops; 652 sector_t blocknr, block_end; 653 int offset; 654 /* 655 * This is the sequential read, so ra_pages * 2 (but try to 656 * align the optimal hardware IO size). 657 * [BTW, 128kb covers the whole sectors for FAT12 and FAT16] 658 */ 659 unsigned long ra_pages = sb->s_bdi->ra_pages; 660 unsigned int reada_blocks; 661 662 if (fatent->entry >= ent_limit) 663 return; 664 665 if (ra_pages > sb->s_bdi->io_pages) 666 ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages); 667 reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1); 668 669 /* Initialize the range for sequential read */ 670 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 671 ops->ent_blocknr(sb, ent_limit - 1, &offset, &block_end); 672 ra->cur = 0; 673 ra->limit = (block_end + 1) - blocknr; 674 675 /* Advancing the window at half size */ 676 ra->ra_blocks = reada_blocks >> 1; 677 ra->ra_advance = ra->cur; 678 ra->ra_next = ra->cur; 679 ra->ra_limit = ra->cur + min_t(sector_t, reada_blocks, ra->limit); 680 } 681 682 /* Assuming to be called before reading a new block (increments ->cur). */ 683 static void fat_ent_reada(struct super_block *sb, struct fatent_ra *ra, 684 struct fat_entry *fatent) 685 { 686 if (ra->ra_next >= ra->ra_limit) 687 return; 688 689 if (ra->cur >= ra->ra_advance) { 690 struct msdos_sb_info *sbi = MSDOS_SB(sb); 691 const struct fatent_operations *ops = sbi->fatent_ops; 692 struct blk_plug plug; 693 sector_t blocknr, diff; 694 int offset; 695 696 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 697 698 diff = blocknr - ra->cur; 699 blk_start_plug(&plug); 700 /* 701 * FIXME: we would want to directly use the bio with 702 * pages to reduce the number of segments. 703 */ 704 for (; ra->ra_next < ra->ra_limit; ra->ra_next++) 705 sb_breadahead(sb, ra->ra_next + diff); 706 blk_finish_plug(&plug); 707 708 /* Advance the readahead window */ 709 ra->ra_advance += ra->ra_blocks; 710 ra->ra_limit += min_t(sector_t, 711 ra->ra_blocks, ra->limit - ra->ra_limit); 712 } 713 ra->cur++; 714 } 715 716 int fat_count_free_clusters(struct super_block *sb) 717 { 718 struct msdos_sb_info *sbi = MSDOS_SB(sb); 719 const struct fatent_operations *ops = sbi->fatent_ops; 720 struct fat_entry fatent; 721 struct fatent_ra fatent_ra; 722 int err = 0, free; 723 724 lock_fat(sbi); 725 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 726 goto out; 727 728 free = 0; 729 fatent_init(&fatent); 730 fatent_set_entry(&fatent, FAT_START_ENT); 731 fat_ra_init(sb, &fatent_ra, &fatent, sbi->max_cluster); 732 while (fatent.entry < sbi->max_cluster) { 733 /* readahead of fat blocks */ 734 fat_ent_reada(sb, &fatent_ra, &fatent); 735 736 err = fat_ent_read_block(sb, &fatent); 737 if (err) 738 goto out; 739 740 do { 741 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 742 free++; 743 } while (fat_ent_next(sbi, &fatent)); 744 cond_resched(); 745 } 746 sbi->free_clusters = free; 747 sbi->free_clus_valid = 1; 748 mark_fsinfo_dirty(sb); 749 fatent_brelse(&fatent); 750 out: 751 unlock_fat(sbi); 752 return err; 753 } 754 755 static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus) 756 { 757 struct msdos_sb_info *sbi = MSDOS_SB(sb); 758 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus), 759 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0); 760 } 761 762 int fat_trim_fs(struct inode *inode, struct fstrim_range *range) 763 { 764 struct super_block *sb = inode->i_sb; 765 struct msdos_sb_info *sbi = MSDOS_SB(sb); 766 const struct fatent_operations *ops = sbi->fatent_ops; 767 struct fat_entry fatent; 768 struct fatent_ra fatent_ra; 769 u64 ent_start, ent_end, minlen, trimmed = 0; 770 u32 free = 0; 771 int err = 0; 772 773 /* 774 * FAT data is organized as clusters, trim at the granulary of cluster. 775 * 776 * fstrim_range is in byte, convert values to cluster index. 777 * Treat sectors before data region as all used, not to trim them. 778 */ 779 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT); 780 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1; 781 minlen = range->minlen >> sbi->cluster_bits; 782 783 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size) 784 return -EINVAL; 785 if (ent_end >= sbi->max_cluster) 786 ent_end = sbi->max_cluster - 1; 787 788 fatent_init(&fatent); 789 lock_fat(sbi); 790 fatent_set_entry(&fatent, ent_start); 791 fat_ra_init(sb, &fatent_ra, &fatent, ent_end + 1); 792 while (fatent.entry <= ent_end) { 793 /* readahead of fat blocks */ 794 fat_ent_reada(sb, &fatent_ra, &fatent); 795 796 err = fat_ent_read_block(sb, &fatent); 797 if (err) 798 goto error; 799 do { 800 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 801 free++; 802 } else if (free) { 803 if (free >= minlen) { 804 u32 clus = fatent.entry - free; 805 806 err = fat_trim_clusters(sb, clus, free); 807 if (err && err != -EOPNOTSUPP) 808 goto error; 809 if (!err) 810 trimmed += free; 811 err = 0; 812 } 813 free = 0; 814 } 815 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end); 816 817 if (fatal_signal_pending(current)) { 818 err = -ERESTARTSYS; 819 goto error; 820 } 821 822 if (need_resched()) { 823 fatent_brelse(&fatent); 824 unlock_fat(sbi); 825 cond_resched(); 826 lock_fat(sbi); 827 } 828 } 829 /* handle scenario when tail entries are all free */ 830 if (free && free >= minlen) { 831 u32 clus = fatent.entry - free; 832 833 err = fat_trim_clusters(sb, clus, free); 834 if (err && err != -EOPNOTSUPP) 835 goto error; 836 if (!err) 837 trimmed += free; 838 err = 0; 839 } 840 841 error: 842 fatent_brelse(&fatent); 843 unlock_fat(sbi); 844 845 range->len = trimmed << sbi->cluster_bits; 846 847 return err; 848 } 849