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 mmb_mark_buffer_dirty(fatent->bhs[0], 174 &MSDOS_I(fatent->fat_inode)->i_metadata_bhs); 175 if (fatent->nr_bhs == 2) 176 mmb_mark_buffer_dirty(fatent->bhs[1], 177 &MSDOS_I(fatent->fat_inode)->i_metadata_bhs); 178 } 179 180 static void fat16_ent_put(struct fat_entry *fatent, int new) 181 { 182 if (new == FAT_ENT_EOF) 183 new = EOF_FAT16; 184 185 *fatent->u.ent16_p = cpu_to_le16(new); 186 mmb_mark_buffer_dirty(fatent->bhs[0], 187 &MSDOS_I(fatent->fat_inode)->i_metadata_bhs); 188 } 189 190 static void fat32_ent_put(struct fat_entry *fatent, int new) 191 { 192 WARN_ON(new & 0xf0000000); 193 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; 194 *fatent->u.ent32_p = cpu_to_le32(new); 195 mmb_mark_buffer_dirty(fatent->bhs[0], 196 &MSDOS_I(fatent->fat_inode)->i_metadata_bhs); 197 } 198 199 static int fat12_ent_next(struct fat_entry *fatent) 200 { 201 u8 **ent12_p = fatent->u.ent12_p; 202 struct buffer_head **bhs = fatent->bhs; 203 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); 204 205 fatent->entry++; 206 if (fatent->nr_bhs == 1) { 207 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + 208 (bhs[0]->b_size - 2))); 209 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + 210 (bhs[0]->b_size - 1))); 211 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { 212 ent12_p[0] = nextp - 1; 213 ent12_p[1] = nextp; 214 return 1; 215 } 216 } else { 217 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + 218 (bhs[0]->b_size - 1))); 219 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); 220 ent12_p[0] = nextp - 1; 221 ent12_p[1] = nextp; 222 brelse(bhs[0]); 223 bhs[0] = bhs[1]; 224 fatent->nr_bhs = 1; 225 return 1; 226 } 227 ent12_p[0] = NULL; 228 ent12_p[1] = NULL; 229 return 0; 230 } 231 232 static int fat16_ent_next(struct fat_entry *fatent) 233 { 234 const struct buffer_head *bh = fatent->bhs[0]; 235 fatent->entry++; 236 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { 237 fatent->u.ent16_p++; 238 return 1; 239 } 240 fatent->u.ent16_p = NULL; 241 return 0; 242 } 243 244 static int fat32_ent_next(struct fat_entry *fatent) 245 { 246 const struct buffer_head *bh = fatent->bhs[0]; 247 fatent->entry++; 248 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { 249 fatent->u.ent32_p++; 250 return 1; 251 } 252 fatent->u.ent32_p = NULL; 253 return 0; 254 } 255 256 static const struct fatent_operations fat12_ops = { 257 .ent_blocknr = fat12_ent_blocknr, 258 .ent_set_ptr = fat12_ent_set_ptr, 259 .ent_bread = fat12_ent_bread, 260 .ent_get = fat12_ent_get, 261 .ent_put = fat12_ent_put, 262 .ent_next = fat12_ent_next, 263 }; 264 265 static const struct fatent_operations fat16_ops = { 266 .ent_blocknr = fat_ent_blocknr, 267 .ent_set_ptr = fat16_ent_set_ptr, 268 .ent_bread = fat_ent_bread, 269 .ent_get = fat16_ent_get, 270 .ent_put = fat16_ent_put, 271 .ent_next = fat16_ent_next, 272 }; 273 274 static const struct fatent_operations fat32_ops = { 275 .ent_blocknr = fat_ent_blocknr, 276 .ent_set_ptr = fat32_ent_set_ptr, 277 .ent_bread = fat_ent_bread, 278 .ent_get = fat32_ent_get, 279 .ent_put = fat32_ent_put, 280 .ent_next = fat32_ent_next, 281 }; 282 283 static inline void lock_fat(struct msdos_sb_info *sbi) 284 { 285 mutex_lock(&sbi->fat_lock); 286 } 287 288 static inline void unlock_fat(struct msdos_sb_info *sbi) 289 { 290 mutex_unlock(&sbi->fat_lock); 291 } 292 293 void fat_ent_access_init(struct super_block *sb) 294 { 295 struct msdos_sb_info *sbi = MSDOS_SB(sb); 296 297 mutex_init(&sbi->fat_lock); 298 299 if (is_fat32(sbi)) { 300 sbi->fatent_shift = 2; 301 sbi->fatent_ops = &fat32_ops; 302 } else if (is_fat16(sbi)) { 303 sbi->fatent_shift = 1; 304 sbi->fatent_ops = &fat16_ops; 305 } else if (is_fat12(sbi)) { 306 sbi->fatent_shift = -1; 307 sbi->fatent_ops = &fat12_ops; 308 } else { 309 fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits); 310 } 311 } 312 313 static void mark_fsinfo_dirty(struct super_block *sb) 314 { 315 struct msdos_sb_info *sbi = MSDOS_SB(sb); 316 317 if (sb_rdonly(sb) || !is_fat32(sbi)) 318 return; 319 320 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); 321 } 322 323 static inline int fat_ent_update_ptr(struct super_block *sb, 324 struct fat_entry *fatent, 325 int offset, sector_t blocknr) 326 { 327 struct msdos_sb_info *sbi = MSDOS_SB(sb); 328 const struct fatent_operations *ops = sbi->fatent_ops; 329 struct buffer_head **bhs = fatent->bhs; 330 331 /* Is this fatent's blocks including this entry? */ 332 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 333 return 0; 334 if (is_fat12(sbi)) { 335 if ((offset + 1) < sb->s_blocksize) { 336 /* This entry is on bhs[0]. */ 337 if (fatent->nr_bhs == 2) { 338 brelse(bhs[1]); 339 fatent->nr_bhs = 1; 340 } 341 } else { 342 /* This entry needs the next block. */ 343 if (fatent->nr_bhs != 2) 344 return 0; 345 if (bhs[1]->b_blocknr != (blocknr + 1)) 346 return 0; 347 } 348 } 349 ops->ent_set_ptr(fatent, offset); 350 return 1; 351 } 352 353 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 354 { 355 struct super_block *sb = inode->i_sb; 356 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 357 const struct fatent_operations *ops = sbi->fatent_ops; 358 int err, offset; 359 sector_t blocknr; 360 361 if (!fat_valid_entry(sbi, entry)) { 362 fatent_brelse(fatent); 363 fat_fs_error_ratelimit(sb, "invalid access to FAT (entry 0x%08x)", entry); 364 return -EIO; 365 } 366 367 fatent_set_entry(fatent, entry); 368 ops->ent_blocknr(sb, entry, &offset, &blocknr); 369 370 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 371 fatent_brelse(fatent); 372 err = ops->ent_bread(sb, fatent, offset, blocknr); 373 if (err) 374 return err; 375 } 376 return ops->ent_get(fatent); 377 } 378 379 /* FIXME: We can write the blocks as more big chunk. */ 380 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 381 int nr_bhs) 382 { 383 struct msdos_sb_info *sbi = MSDOS_SB(sb); 384 struct buffer_head *c_bh; 385 int err, n, copy; 386 387 err = 0; 388 for (copy = 1; copy < sbi->fats; copy++) { 389 sector_t backup_fat = sbi->fat_length * copy; 390 391 for (n = 0; n < nr_bhs; n++) { 392 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 393 if (!c_bh) { 394 err = -ENOMEM; 395 goto error; 396 } 397 /* Avoid race with userspace read via bdev */ 398 lock_buffer(c_bh); 399 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 400 set_buffer_uptodate(c_bh); 401 unlock_buffer(c_bh); 402 mmb_mark_buffer_dirty(c_bh, 403 &MSDOS_I(sbi->fat_inode)->i_metadata_bhs); 404 if (sb->s_flags & SB_SYNCHRONOUS) 405 err = sync_dirty_buffer(c_bh); 406 brelse(c_bh); 407 if (err) 408 goto error; 409 } 410 } 411 error: 412 return err; 413 } 414 415 int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 416 int new, int wait) 417 { 418 struct super_block *sb = inode->i_sb; 419 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 420 int err; 421 422 ops->ent_put(fatent, new); 423 if (wait) { 424 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 425 if (err) 426 return err; 427 } 428 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 429 } 430 431 static inline int fat_ent_next(struct msdos_sb_info *sbi, 432 struct fat_entry *fatent) 433 { 434 if (sbi->fatent_ops->ent_next(fatent)) { 435 if (fatent->entry < sbi->max_cluster) 436 return 1; 437 } 438 return 0; 439 } 440 441 static inline int fat_ent_read_block(struct super_block *sb, 442 struct fat_entry *fatent) 443 { 444 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 445 sector_t blocknr; 446 int offset; 447 448 fatent_brelse(fatent); 449 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 450 return ops->ent_bread(sb, fatent, offset, blocknr); 451 } 452 453 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 454 struct fat_entry *fatent) 455 { 456 int n, i; 457 458 for (n = 0; n < fatent->nr_bhs; n++) { 459 for (i = 0; i < *nr_bhs; i++) { 460 if (fatent->bhs[n] == bhs[i]) 461 break; 462 } 463 if (i == *nr_bhs) { 464 get_bh(fatent->bhs[n]); 465 bhs[i] = fatent->bhs[n]; 466 (*nr_bhs)++; 467 } 468 } 469 } 470 471 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 472 { 473 struct super_block *sb = inode->i_sb; 474 struct msdos_sb_info *sbi = MSDOS_SB(sb); 475 const struct fatent_operations *ops = sbi->fatent_ops; 476 struct fat_entry fatent, prev_ent; 477 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 478 int i, count, err, nr_bhs, idx_clus; 479 480 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 481 482 lock_fat(sbi); 483 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 484 sbi->free_clusters < nr_cluster) { 485 unlock_fat(sbi); 486 return -ENOSPC; 487 } 488 489 err = nr_bhs = idx_clus = 0; 490 count = FAT_START_ENT; 491 fatent_init(&prev_ent); 492 fatent_init(&fatent); 493 fatent_set_entry(&fatent, sbi->prev_free + 1); 494 while (count < sbi->max_cluster) { 495 if (fatent.entry >= sbi->max_cluster) 496 fatent.entry = FAT_START_ENT; 497 fatent_set_entry(&fatent, fatent.entry); 498 err = fat_ent_read_block(sb, &fatent); 499 if (err) 500 goto out; 501 502 /* Find the free entries in a block */ 503 do { 504 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 505 int entry = fatent.entry; 506 507 /* make the cluster chain */ 508 ops->ent_put(&fatent, FAT_ENT_EOF); 509 if (prev_ent.nr_bhs) 510 ops->ent_put(&prev_ent, entry); 511 512 fat_collect_bhs(bhs, &nr_bhs, &fatent); 513 514 sbi->prev_free = entry; 515 if (sbi->free_clusters != -1) 516 sbi->free_clusters--; 517 518 cluster[idx_clus] = entry; 519 idx_clus++; 520 if (idx_clus == nr_cluster) 521 goto out; 522 523 /* 524 * fat_collect_bhs() gets ref-count of bhs, 525 * so we can still use the prev_ent. 526 */ 527 prev_ent = fatent; 528 } 529 count++; 530 if (count == sbi->max_cluster) 531 break; 532 } while (fat_ent_next(sbi, &fatent)); 533 } 534 535 /* Couldn't allocate the free entries */ 536 sbi->free_clusters = 0; 537 sbi->free_clus_valid = 1; 538 err = -ENOSPC; 539 540 out: 541 unlock_fat(sbi); 542 mark_fsinfo_dirty(sb); 543 fatent_brelse(&fatent); 544 if (!err) { 545 if (inode_needs_sync(inode)) 546 err = fat_sync_bhs(bhs, nr_bhs); 547 if (!err) 548 err = fat_mirror_bhs(sb, bhs, nr_bhs); 549 } 550 for (i = 0; i < nr_bhs; i++) 551 brelse(bhs[i]); 552 553 if (err && idx_clus) 554 fat_free_clusters(inode, cluster[0]); 555 556 return err; 557 } 558 559 int fat_free_clusters(struct inode *inode, int cluster) 560 { 561 struct super_block *sb = inode->i_sb; 562 struct msdos_sb_info *sbi = MSDOS_SB(sb); 563 const struct fatent_operations *ops = sbi->fatent_ops; 564 struct fat_entry fatent; 565 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 566 int i, err, nr_bhs; 567 int first_cl = cluster, dirty_fsinfo = 0; 568 569 nr_bhs = 0; 570 fatent_init(&fatent); 571 lock_fat(sbi); 572 do { 573 cluster = fat_ent_read(inode, &fatent, cluster); 574 if (cluster < 0) { 575 err = cluster; 576 goto error; 577 } else if (cluster == FAT_ENT_FREE) { 578 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", 579 __func__); 580 err = -EIO; 581 goto error; 582 } 583 584 if (sbi->options.discard) { 585 /* 586 * Issue discard for the sectors we no longer 587 * care about, batching contiguous clusters 588 * into one request 589 */ 590 if (cluster != fatent.entry + 1) { 591 int nr_clus = fatent.entry - first_cl + 1; 592 593 sb_issue_discard(sb, 594 fat_clus_to_blknr(sbi, first_cl), 595 nr_clus * sbi->sec_per_clus, 596 GFP_NOFS, 0); 597 598 first_cl = cluster; 599 } 600 } 601 602 ops->ent_put(&fatent, FAT_ENT_FREE); 603 if (sbi->free_clusters != -1) { 604 sbi->free_clusters++; 605 dirty_fsinfo = 1; 606 } 607 608 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 609 if (sb->s_flags & SB_SYNCHRONOUS) { 610 err = fat_sync_bhs(bhs, nr_bhs); 611 if (err) 612 goto error; 613 } 614 err = fat_mirror_bhs(sb, bhs, nr_bhs); 615 if (err) 616 goto error; 617 for (i = 0; i < nr_bhs; i++) 618 brelse(bhs[i]); 619 nr_bhs = 0; 620 } 621 fat_collect_bhs(bhs, &nr_bhs, &fatent); 622 } while (cluster != FAT_ENT_EOF); 623 624 if (sb->s_flags & SB_SYNCHRONOUS) { 625 err = fat_sync_bhs(bhs, nr_bhs); 626 if (err) 627 goto error; 628 } 629 err = fat_mirror_bhs(sb, bhs, nr_bhs); 630 error: 631 fatent_brelse(&fatent); 632 for (i = 0; i < nr_bhs; i++) 633 brelse(bhs[i]); 634 unlock_fat(sbi); 635 if (dirty_fsinfo) 636 mark_fsinfo_dirty(sb); 637 638 return err; 639 } 640 EXPORT_SYMBOL_GPL(fat_free_clusters); 641 642 struct fatent_ra { 643 sector_t cur; 644 sector_t limit; 645 646 unsigned int ra_blocks; 647 sector_t ra_advance; 648 sector_t ra_next; 649 sector_t ra_limit; 650 }; 651 652 static void fat_ra_init(struct super_block *sb, struct fatent_ra *ra, 653 struct fat_entry *fatent, int ent_limit) 654 { 655 struct msdos_sb_info *sbi = MSDOS_SB(sb); 656 const struct fatent_operations *ops = sbi->fatent_ops; 657 sector_t blocknr, block_end; 658 int offset; 659 /* 660 * This is the sequential read, so ra_pages * 2 (but try to 661 * align the optimal hardware IO size). 662 * [BTW, 128kb covers the whole sectors for FAT12 and FAT16] 663 */ 664 unsigned long ra_pages = sb->s_bdi->ra_pages; 665 unsigned int reada_blocks; 666 667 if (fatent->entry >= ent_limit) 668 return; 669 670 if (ra_pages > sb->s_bdi->io_pages) 671 ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages); 672 reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1); 673 674 /* Initialize the range for sequential read */ 675 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 676 ops->ent_blocknr(sb, ent_limit - 1, &offset, &block_end); 677 ra->cur = 0; 678 ra->limit = (block_end + 1) - blocknr; 679 680 /* Advancing the window at half size */ 681 ra->ra_blocks = reada_blocks >> 1; 682 ra->ra_advance = ra->cur; 683 ra->ra_next = ra->cur; 684 ra->ra_limit = ra->cur + min_t(sector_t, reada_blocks, ra->limit); 685 } 686 687 /* Assuming to be called before reading a new block (increments ->cur). */ 688 static void fat_ent_reada(struct super_block *sb, struct fatent_ra *ra, 689 struct fat_entry *fatent) 690 { 691 if (ra->ra_next >= ra->ra_limit) 692 return; 693 694 if (ra->cur >= ra->ra_advance) { 695 struct msdos_sb_info *sbi = MSDOS_SB(sb); 696 const struct fatent_operations *ops = sbi->fatent_ops; 697 struct blk_plug plug; 698 sector_t blocknr, diff; 699 int offset; 700 701 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 702 703 diff = blocknr - ra->cur; 704 blk_start_plug(&plug); 705 /* 706 * FIXME: we would want to directly use the bio with 707 * pages to reduce the number of segments. 708 */ 709 for (; ra->ra_next < ra->ra_limit; ra->ra_next++) 710 sb_breadahead(sb, ra->ra_next + diff); 711 blk_finish_plug(&plug); 712 713 /* Advance the readahead window */ 714 ra->ra_advance += ra->ra_blocks; 715 ra->ra_limit += min_t(sector_t, 716 ra->ra_blocks, ra->limit - ra->ra_limit); 717 } 718 ra->cur++; 719 } 720 721 int fat_count_free_clusters(struct super_block *sb) 722 { 723 struct msdos_sb_info *sbi = MSDOS_SB(sb); 724 const struct fatent_operations *ops = sbi->fatent_ops; 725 struct fat_entry fatent; 726 struct fatent_ra fatent_ra; 727 int err = 0, free; 728 729 lock_fat(sbi); 730 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 731 goto out; 732 733 free = 0; 734 fatent_init(&fatent); 735 fatent_set_entry(&fatent, FAT_START_ENT); 736 fat_ra_init(sb, &fatent_ra, &fatent, sbi->max_cluster); 737 while (fatent.entry < sbi->max_cluster) { 738 /* readahead of fat blocks */ 739 fat_ent_reada(sb, &fatent_ra, &fatent); 740 741 err = fat_ent_read_block(sb, &fatent); 742 if (err) 743 goto out; 744 745 do { 746 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 747 free++; 748 } while (fat_ent_next(sbi, &fatent)); 749 cond_resched(); 750 } 751 sbi->free_clusters = free; 752 sbi->free_clus_valid = 1; 753 mark_fsinfo_dirty(sb); 754 fatent_brelse(&fatent); 755 out: 756 unlock_fat(sbi); 757 return err; 758 } 759 760 static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus) 761 { 762 struct msdos_sb_info *sbi = MSDOS_SB(sb); 763 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus), 764 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0); 765 } 766 767 int fat_trim_fs(struct inode *inode, struct fstrim_range *range) 768 { 769 struct super_block *sb = inode->i_sb; 770 struct msdos_sb_info *sbi = MSDOS_SB(sb); 771 const struct fatent_operations *ops = sbi->fatent_ops; 772 struct fat_entry fatent; 773 struct fatent_ra fatent_ra; 774 u64 ent_start, ent_end, minlen, trimmed = 0; 775 u32 free = 0; 776 int err = 0; 777 778 /* 779 * FAT data is organized as clusters, trim at the granulary of cluster. 780 * 781 * fstrim_range is in byte, convert values to cluster index. 782 * Treat sectors before data region as all used, not to trim them. 783 */ 784 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT); 785 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1; 786 minlen = range->minlen >> sbi->cluster_bits; 787 788 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size) 789 return -EINVAL; 790 if (ent_end >= sbi->max_cluster) 791 ent_end = sbi->max_cluster - 1; 792 793 fatent_init(&fatent); 794 lock_fat(sbi); 795 fatent_set_entry(&fatent, ent_start); 796 fat_ra_init(sb, &fatent_ra, &fatent, ent_end + 1); 797 while (fatent.entry <= ent_end) { 798 /* readahead of fat blocks */ 799 fat_ent_reada(sb, &fatent_ra, &fatent); 800 801 err = fat_ent_read_block(sb, &fatent); 802 if (err) 803 goto error; 804 do { 805 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 806 free++; 807 } else if (free) { 808 if (free >= minlen) { 809 u32 clus = fatent.entry - free; 810 811 err = fat_trim_clusters(sb, clus, free); 812 if (err && err != -EOPNOTSUPP) 813 goto error; 814 if (!err) 815 trimmed += free; 816 err = 0; 817 } 818 free = 0; 819 } 820 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end); 821 822 if (fatal_signal_pending(current)) { 823 err = -ERESTARTSYS; 824 goto error; 825 } 826 827 if (need_resched()) { 828 fatent_brelse(&fatent); 829 unlock_fat(sbi); 830 cond_resched(); 831 lock_fat(sbi); 832 } 833 } 834 /* handle scenario when tail entries are all free */ 835 if (free && free >= minlen) { 836 u32 clus = fatent.entry - free; 837 838 err = fat_trim_clusters(sb, clus, free); 839 if (err && err != -EOPNOTSUPP) 840 goto error; 841 if (!err) 842 trimmed += free; 843 err = 0; 844 } 845 846 error: 847 fatent_brelse(&fatent); 848 unlock_fat(sbi); 849 850 range->len = trimmed << sbi->cluster_bits; 851 852 return err; 853 } 854