849 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2004, OGAWA Hirofumi4 */5 6#include <linux/blkdev.h>7#include <linux/sched/signal.h>8#include <linux/backing-dev-defs.h>9#include "fat.h"10 11struct 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 21static DEFINE_SPINLOCK(fat12_entry_lock);22 23static 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 33static 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 43static 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 57static 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 63static 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 69static 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 94err_brelse:95 brelse(bhs[0]);96err:97 fat_msg_ratelimit(sb, KERN_ERR, "FAT read failed (blocknr %llu)",98 (llu)blocknr);99 return -EIO;100}101 102static 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 120static 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 else129 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 138static 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 147static 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 156static 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 178static 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 187static 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 195static 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 228static 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 240static 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 252static 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 261static 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 270static 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 279static inline void lock_fat(struct msdos_sb_info *sbi)280{281 mutex_lock(&sbi->fat_lock);282}283 284static inline void unlock_fat(struct msdos_sb_info *sbi)285{286 mutex_unlock(&sbi->fat_lock);287}288 289void 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 309static 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 319static 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 349int 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. */376static 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 }406error:407 return err;408}409 410int 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 426static 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 436static 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 448static 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 466int 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 535out: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 554int 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 longer582 * care about, batching contiguous clusters583 * into one request584 */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);625error: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}635EXPORT_SYMBOL_GPL(fat_free_clusters);636 637struct 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 647static 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 to656 * 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). */683static 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 with702 * 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 716int 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);750out:751 unlock_fat(sbi);752 return err;753}754 755static 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 762int 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 841error:842 fatent_brelse(&fatent);843 unlock_fat(sbi);844 845 range->len = trimmed << sbi->cluster_bits;846 847 return err;848}849