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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * linux/fs/fat/inode.c4 *5 * Written 1992,1993 by Werner Almesberger6 * VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner7 * Rewritten for the constant inumbers support by Al Viro8 *9 * Fixes:10 *11 * Max Cohan: Fixed invalid FSINFO offset when info_sector is 012 */13 14#include <linux/module.h>15#include <linux/pagemap.h>16#include <linux/mpage.h>17#include <linux/vfs.h>18#include <linux/seq_file.h>19#include <linux/uio.h>20#include <linux/blkdev.h>21#include <linux/backing-dev.h>22#include <linux/unaligned.h>23#include <linux/random.h>24#include <linux/iversion.h>25#include "fat.h"26 27#ifndef CONFIG_FAT_DEFAULT_IOCHARSET28/* if user don't select VFAT, this is undefined. */29#define CONFIG_FAT_DEFAULT_IOCHARSET ""30#endif31 32#define KB_IN_SECTORS 233 34/* DOS dates from 1980/1/1 through 2107/12/31 */35#define FAT_DATE_MIN (0<<9 | 1<<5 | 1)36#define FAT_DATE_MAX (127<<9 | 12<<5 | 31)37#define FAT_TIME_MAX (23<<11 | 59<<5 | 29)38 39/*40 * A deserialized copy of the on-disk structure laid out in struct41 * fat_boot_sector.42 */43struct fat_bios_param_block {44 u16 fat_sector_size;45 u8 fat_sec_per_clus;46 u16 fat_reserved;47 u8 fat_fats;48 u16 fat_dir_entries;49 u16 fat_sectors;50 u16 fat_fat_length;51 u32 fat_total_sect;52 53 u8 fat16_state;54 u32 fat16_vol_id;55 56 u32 fat32_length;57 u32 fat32_root_cluster;58 u16 fat32_info_sector;59 u8 fat32_state;60 u32 fat32_vol_id;61};62 63static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;64static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;65 66static struct fat_floppy_defaults {67 unsigned nr_sectors;68 unsigned sec_per_clus;69 unsigned dir_entries;70 unsigned media;71 unsigned fat_length;72} floppy_defaults[] = {73{74 .nr_sectors = 160 * KB_IN_SECTORS,75 .sec_per_clus = 1,76 .dir_entries = 64,77 .media = 0xFE,78 .fat_length = 1,79},80{81 .nr_sectors = 180 * KB_IN_SECTORS,82 .sec_per_clus = 1,83 .dir_entries = 64,84 .media = 0xFC,85 .fat_length = 2,86},87{88 .nr_sectors = 320 * KB_IN_SECTORS,89 .sec_per_clus = 2,90 .dir_entries = 112,91 .media = 0xFF,92 .fat_length = 1,93},94{95 .nr_sectors = 360 * KB_IN_SECTORS,96 .sec_per_clus = 2,97 .dir_entries = 112,98 .media = 0xFD,99 .fat_length = 2,100},101};102 103int fat_add_cluster(struct inode *inode)104{105 int err, cluster;106 107 err = fat_alloc_clusters(inode, &cluster, 1);108 if (err)109 return err;110 /* FIXME: this cluster should be added after data of this111 * cluster is writed */112 err = fat_chain_add(inode, cluster, 1);113 if (err)114 fat_free_clusters(inode, cluster);115 return err;116}117 118static inline int __fat_get_block(struct inode *inode, sector_t iblock,119 unsigned long *max_blocks,120 struct buffer_head *bh_result, int create)121{122 struct super_block *sb = inode->i_sb;123 struct msdos_sb_info *sbi = MSDOS_SB(sb);124 unsigned long mapped_blocks;125 sector_t phys, last_block;126 int err, offset;127 128 err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);129 if (err)130 return err;131 if (phys) {132 map_bh(bh_result, sb, phys);133 *max_blocks = min(mapped_blocks, *max_blocks);134 return 0;135 }136 if (!create)137 return 0;138 139 if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {140 fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",141 MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);142 return -EIO;143 }144 145 last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);146 offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);147 /*148 * allocate a cluster according to the following.149 * 1) no more available blocks150 * 2) not part of fallocate region151 */152 if (!offset && !(iblock < last_block)) {153 /* TODO: multiple cluster allocation would be desirable. */154 err = fat_add_cluster(inode);155 if (err)156 return err;157 }158 /* available blocks on this cluster */159 mapped_blocks = sbi->sec_per_clus - offset;160 161 *max_blocks = min(mapped_blocks, *max_blocks);162 MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;163 164 err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);165 if (err)166 return err;167 if (!phys) {168 fat_fs_error(sb,169 "invalid FAT chain (i_pos %lld, last_block %llu)",170 MSDOS_I(inode)->i_pos,171 (unsigned long long)last_block);172 return -EIO;173 }174 175 BUG_ON(*max_blocks != mapped_blocks);176 set_buffer_new(bh_result);177 map_bh(bh_result, sb, phys);178 179 return 0;180}181 182static int fat_get_block(struct inode *inode, sector_t iblock,183 struct buffer_head *bh_result, int create)184{185 struct super_block *sb = inode->i_sb;186 unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;187 int err;188 189 err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);190 if (err)191 return err;192 bh_result->b_size = max_blocks << sb->s_blocksize_bits;193 return 0;194}195 196static int fat_writepages(struct address_space *mapping,197 struct writeback_control *wbc)198{199 return mpage_writepages(mapping, wbc, fat_get_block);200}201 202static int fat_read_folio(struct file *file, struct folio *folio)203{204 return mpage_read_folio(folio, fat_get_block);205}206 207static void fat_readahead(struct readahead_control *rac)208{209 mpage_readahead(rac, fat_get_block);210}211 212static void fat_write_failed(struct address_space *mapping, loff_t to)213{214 struct inode *inode = mapping->host;215 216 if (to > inode->i_size) {217 truncate_pagecache(inode, inode->i_size);218 fat_truncate_blocks(inode, inode->i_size);219 }220}221 222static int fat_write_begin(struct file *file, struct address_space *mapping,223 loff_t pos, unsigned len,224 struct folio **foliop, void **fsdata)225{226 int err;227 228 err = cont_write_begin(file, mapping, pos, len,229 foliop, fsdata, fat_get_block,230 &MSDOS_I(mapping->host)->mmu_private);231 if (err < 0)232 fat_write_failed(mapping, pos + len);233 return err;234}235 236static int fat_write_end(struct file *file, struct address_space *mapping,237 loff_t pos, unsigned len, unsigned copied,238 struct folio *folio, void *fsdata)239{240 struct inode *inode = mapping->host;241 int err;242 err = generic_write_end(file, mapping, pos, len, copied, folio, fsdata);243 if (err < len)244 fat_write_failed(mapping, pos + len);245 if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {246 fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);247 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;248 mark_inode_dirty(inode);249 }250 return err;251}252 253static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)254{255 struct file *file = iocb->ki_filp;256 struct address_space *mapping = file->f_mapping;257 struct inode *inode = mapping->host;258 size_t count = iov_iter_count(iter);259 loff_t offset = iocb->ki_pos;260 ssize_t ret;261 262 if (iov_iter_rw(iter) == WRITE) {263 /*264 * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),265 * so we need to update the ->mmu_private to block boundary.266 *267 * But we must fill the remaining area or hole by nul for268 * updating ->mmu_private.269 *270 * Return 0, and fallback to normal buffered write.271 */272 loff_t size = offset + count;273 if (MSDOS_I(inode)->mmu_private < size)274 return 0;275 }276 277 /*278 * FAT need to use the DIO_LOCKING for avoiding the race279 * condition of fat_get_block() and ->truncate().280 */281 ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);282 if (ret < 0 && iov_iter_rw(iter) == WRITE)283 fat_write_failed(mapping, offset + count);284 285 return ret;286}287 288static int fat_get_block_bmap(struct inode *inode, sector_t iblock,289 struct buffer_head *bh_result, int create)290{291 struct super_block *sb = inode->i_sb;292 unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;293 int err;294 sector_t bmap;295 unsigned long mapped_blocks;296 297 BUG_ON(create != 0);298 299 err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);300 if (err)301 return err;302 303 if (bmap) {304 map_bh(bh_result, sb, bmap);305 max_blocks = min(mapped_blocks, max_blocks);306 }307 308 bh_result->b_size = max_blocks << sb->s_blocksize_bits;309 310 return 0;311}312 313static sector_t _fat_bmap(struct address_space *mapping, sector_t block)314{315 sector_t blocknr;316 317 /* fat_get_cluster() assumes the requested blocknr isn't truncated. */318 down_read(&MSDOS_I(mapping->host)->truncate_lock);319 blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);320 up_read(&MSDOS_I(mapping->host)->truncate_lock);321 322 return blocknr;323}324 325/*326 * fat_block_truncate_page() zeroes out a mapping from file offset `from'327 * up to the end of the block which corresponds to `from'.328 * This is required during truncate to physically zeroout the tail end329 * of that block so it doesn't yield old data if the file is later grown.330 * Also, avoid causing failure from fsx for cases of "data past EOF"331 */332int fat_block_truncate_page(struct inode *inode, loff_t from)333{334 return block_truncate_page(inode->i_mapping, from, fat_get_block);335}336 337static const struct address_space_operations fat_aops = {338 .dirty_folio = block_dirty_folio,339 .invalidate_folio = block_invalidate_folio,340 .read_folio = fat_read_folio,341 .readahead = fat_readahead,342 .writepages = fat_writepages,343 .write_begin = fat_write_begin,344 .write_end = fat_write_end,345 .direct_IO = fat_direct_IO,346 .bmap = _fat_bmap,347 .migrate_folio = buffer_migrate_folio,348};349 350/*351 * New FAT inode stuff. We do the following:352 * a) i_ino is constant and has nothing with on-disk location.353 * b) FAT manages its own cache of directory entries.354 * c) *This* cache is indexed by on-disk location.355 * d) inode has an associated directory entry, all right, but356 * it may be unhashed.357 * e) currently entries are stored within struct inode. That should358 * change.359 * f) we deal with races in the following way:360 * 1. readdir() and lookup() do FAT-dir-cache lookup.361 * 2. rename() unhashes the F-d-c entry and rehashes it in362 * a new place.363 * 3. unlink() and rmdir() unhash F-d-c entry.364 * 4. fat_write_inode() checks whether the thing is unhashed.365 * If it is we silently return. If it isn't we do bread(),366 * check if the location is still valid and retry if it367 * isn't. Otherwise we do changes.368 * 5. Spinlock is used to protect hash/unhash/location check/lookup369 * 6. fat_evict_inode() unhashes the F-d-c entry.370 * 7. lookup() and readdir() do igrab() if they find a F-d-c entry371 * and consider negative result as cache miss.372 */373 374static void fat_hash_init(struct super_block *sb)375{376 struct msdos_sb_info *sbi = MSDOS_SB(sb);377 int i;378 379 spin_lock_init(&sbi->inode_hash_lock);380 for (i = 0; i < FAT_HASH_SIZE; i++)381 INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);382}383 384static inline unsigned long fat_hash(loff_t i_pos)385{386 return hash_32(i_pos, FAT_HASH_BITS);387}388 389static void dir_hash_init(struct super_block *sb)390{391 struct msdos_sb_info *sbi = MSDOS_SB(sb);392 int i;393 394 spin_lock_init(&sbi->dir_hash_lock);395 for (i = 0; i < FAT_HASH_SIZE; i++)396 INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);397}398 399void fat_attach(struct inode *inode, loff_t i_pos)400{401 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);402 403 if (inode->i_ino != MSDOS_ROOT_INO) {404 struct hlist_head *head = sbi->inode_hashtable405 + fat_hash(i_pos);406 407 spin_lock(&sbi->inode_hash_lock);408 MSDOS_I(inode)->i_pos = i_pos;409 hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);410 spin_unlock(&sbi->inode_hash_lock);411 }412 413 /* If NFS support is enabled, cache the mapping of start cluster414 * to directory inode. This is used during reconnection of415 * dentries to the filesystem root.416 */417 if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {418 struct hlist_head *d_head = sbi->dir_hashtable;419 d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);420 421 spin_lock(&sbi->dir_hash_lock);422 hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);423 spin_unlock(&sbi->dir_hash_lock);424 }425}426EXPORT_SYMBOL_GPL(fat_attach);427 428void fat_detach(struct inode *inode)429{430 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);431 spin_lock(&sbi->inode_hash_lock);432 MSDOS_I(inode)->i_pos = 0;433 hlist_del_init(&MSDOS_I(inode)->i_fat_hash);434 spin_unlock(&sbi->inode_hash_lock);435 436 if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {437 spin_lock(&sbi->dir_hash_lock);438 hlist_del_init(&MSDOS_I(inode)->i_dir_hash);439 spin_unlock(&sbi->dir_hash_lock);440 }441}442EXPORT_SYMBOL_GPL(fat_detach);443 444struct inode *fat_iget(struct super_block *sb, loff_t i_pos)445{446 struct msdos_sb_info *sbi = MSDOS_SB(sb);447 struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);448 struct msdos_inode_info *i;449 struct inode *inode = NULL;450 451 spin_lock(&sbi->inode_hash_lock);452 hlist_for_each_entry(i, head, i_fat_hash) {453 BUG_ON(i->vfs_inode.i_sb != sb);454 if (i->i_pos != i_pos)455 continue;456 inode = igrab(&i->vfs_inode);457 if (inode)458 break;459 }460 spin_unlock(&sbi->inode_hash_lock);461 return inode;462}463 464static int is_exec(unsigned char *extension)465{466 unsigned char exe_extensions[] = "EXECOMBAT", *walk;467 468 for (walk = exe_extensions; *walk; walk += 3)469 if (!strncmp(extension, walk, 3))470 return 1;471 return 0;472}473 474static int fat_calc_dir_size(struct inode *inode)475{476 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);477 int ret, fclus, dclus;478 479 inode->i_size = 0;480 if (MSDOS_I(inode)->i_start == 0)481 return 0;482 483 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);484 if (ret < 0)485 return ret;486 inode->i_size = (fclus + 1) << sbi->cluster_bits;487 488 return 0;489}490 491static int fat_validate_dir(struct inode *dir)492{493 struct super_block *sb = dir->i_sb;494 495 if (dir->i_nlink < 2) {496 /* Directory should have "."/".." entries at least. */497 fat_fs_error(sb, "corrupted directory (invalid entries)");498 return -EIO;499 }500 if (MSDOS_I(dir)->i_start == 0 ||501 MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {502 /* Directory should point valid cluster. */503 fat_fs_error(sb, "corrupted directory (invalid i_start)");504 return -EIO;505 }506 return 0;507}508 509/* doesn't deal with root inode */510int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)511{512 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);513 struct timespec64 mtime;514 int error;515 516 MSDOS_I(inode)->i_pos = 0;517 inode->i_uid = sbi->options.fs_uid;518 inode->i_gid = sbi->options.fs_gid;519 inode_inc_iversion(inode);520 inode->i_generation = get_random_u32();521 522 if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {523 inode->i_generation &= ~1;524 inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);525 inode->i_op = sbi->dir_ops;526 inode->i_fop = &fat_dir_operations;527 528 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);529 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;530 error = fat_calc_dir_size(inode);531 if (error < 0)532 return error;533 MSDOS_I(inode)->mmu_private = inode->i_size;534 535 set_nlink(inode, fat_subdirs(inode));536 537 error = fat_validate_dir(inode);538 if (error < 0)539 return error;540 } else { /* not a directory */541 inode->i_generation |= 1;542 inode->i_mode = fat_make_mode(sbi, de->attr,543 ((sbi->options.showexec && !is_exec(de->name + 8))544 ? S_IRUGO|S_IWUGO : S_IRWXUGO));545 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);546 547 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;548 inode->i_size = le32_to_cpu(de->size);549 inode->i_op = &fat_file_inode_operations;550 inode->i_fop = &fat_file_operations;551 inode->i_mapping->a_ops = &fat_aops;552 MSDOS_I(inode)->mmu_private = inode->i_size;553 }554 if (de->attr & ATTR_SYS) {555 if (sbi->options.sys_immutable)556 inode->i_flags |= S_IMMUTABLE;557 }558 fat_save_attrs(inode, de->attr);559 560 inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))561 & ~((loff_t)sbi->cluster_size - 1)) >> 9;562 563 fat_time_fat2unix(sbi, &mtime, de->time, de->date, 0);564 inode_set_mtime_to_ts(inode, mtime);565 inode_set_ctime_to_ts(inode, mtime);566 if (sbi->options.isvfat) {567 struct timespec64 atime;568 569 fat_time_fat2unix(sbi, &atime, 0, de->adate, 0);570 inode_set_atime_to_ts(inode, atime);571 fat_time_fat2unix(sbi, &MSDOS_I(inode)->i_crtime, de->ctime,572 de->cdate, de->ctime_cs);573 } else574 inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, &mtime));575 576 return 0;577}578 579static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)580{581 if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)582 mutex_lock(&sbi->nfs_build_inode_lock);583}584 585static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)586{587 if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)588 mutex_unlock(&sbi->nfs_build_inode_lock);589}590 591struct inode *fat_build_inode(struct super_block *sb,592 struct msdos_dir_entry *de, loff_t i_pos)593{594 struct inode *inode;595 int err;596 597 fat_lock_build_inode(MSDOS_SB(sb));598 inode = fat_iget(sb, i_pos);599 if (inode)600 goto out;601 inode = new_inode(sb);602 if (!inode) {603 inode = ERR_PTR(-ENOMEM);604 goto out;605 }606 inode->i_ino = iunique(sb, MSDOS_ROOT_INO);607 inode_set_iversion(inode, 1);608 err = fat_fill_inode(inode, de);609 if (err) {610 iput(inode);611 inode = ERR_PTR(err);612 goto out;613 }614 fat_attach(inode, i_pos);615 insert_inode_hash(inode);616out:617 fat_unlock_build_inode(MSDOS_SB(sb));618 return inode;619}620 621EXPORT_SYMBOL_GPL(fat_build_inode);622 623static int __fat_write_inode(struct inode *inode, int wait);624 625static void fat_free_eofblocks(struct inode *inode)626{627 /* Release unwritten fallocated blocks on inode eviction. */628 if ((inode->i_blocks << 9) >629 round_up(MSDOS_I(inode)->mmu_private,630 MSDOS_SB(inode->i_sb)->cluster_size)) {631 int err;632 633 fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);634 /* Fallocate results in updating the i_start/iogstart635 * for the zero byte file. So, make it return to636 * original state during evict and commit it to avoid637 * any corruption on the next access to the cluster638 * chain for the file.639 */640 err = __fat_write_inode(inode, inode_needs_sync(inode));641 if (err) {642 fat_msg(inode->i_sb, KERN_WARNING, "Failed to "643 "update on disk inode for unused "644 "fallocated blocks, inode could be "645 "corrupted. Please run fsck");646 }647 648 }649}650 651static void fat_evict_inode(struct inode *inode)652{653 truncate_inode_pages_final(&inode->i_data);654 if (!inode->i_nlink) {655 inode->i_size = 0;656 fat_truncate_blocks(inode, 0);657 } else658 fat_free_eofblocks(inode);659 660 invalidate_inode_buffers(inode);661 clear_inode(inode);662 fat_cache_inval_inode(inode);663 fat_detach(inode);664}665 666static void fat_set_state(struct super_block *sb,667 unsigned int set, unsigned int force)668{669 struct buffer_head *bh;670 struct fat_boot_sector *b;671 struct msdos_sb_info *sbi = MSDOS_SB(sb);672 673 /* do not change any thing if mounted read only */674 if (sb_rdonly(sb) && !force)675 return;676 677 /* do not change state if fs was dirty */678 if (sbi->dirty) {679 /* warn only on set (mount). */680 if (set)681 fat_msg(sb, KERN_WARNING, "Volume was not properly "682 "unmounted. Some data may be corrupt. "683 "Please run fsck.");684 return;685 }686 687 bh = sb_bread(sb, 0);688 if (bh == NULL) {689 fat_msg(sb, KERN_ERR, "unable to read boot sector "690 "to mark fs as dirty");691 return;692 }693 694 b = (struct fat_boot_sector *) bh->b_data;695 696 if (is_fat32(sbi)) {697 if (set)698 b->fat32.state |= FAT_STATE_DIRTY;699 else700 b->fat32.state &= ~FAT_STATE_DIRTY;701 } else /* fat 16 and 12 */ {702 if (set)703 b->fat16.state |= FAT_STATE_DIRTY;704 else705 b->fat16.state &= ~FAT_STATE_DIRTY;706 }707 708 mark_buffer_dirty(bh);709 sync_dirty_buffer(bh);710 brelse(bh);711}712 713static void fat_reset_iocharset(struct fat_mount_options *opts)714{715 if (opts->iocharset != fat_default_iocharset) {716 /* Note: opts->iocharset can be NULL here */717 kfree(opts->iocharset);718 opts->iocharset = fat_default_iocharset;719 }720}721 722static void delayed_free(struct rcu_head *p)723{724 struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);725 unload_nls(sbi->nls_disk);726 unload_nls(sbi->nls_io);727 fat_reset_iocharset(&sbi->options);728 kfree(sbi);729}730 731static void fat_put_super(struct super_block *sb)732{733 struct msdos_sb_info *sbi = MSDOS_SB(sb);734 735 fat_set_state(sb, 0, 0);736 737 iput(sbi->fsinfo_inode);738 iput(sbi->fat_inode);739 740 call_rcu(&sbi->rcu, delayed_free);741}742 743static struct kmem_cache *fat_inode_cachep;744 745static struct inode *fat_alloc_inode(struct super_block *sb)746{747 struct msdos_inode_info *ei;748 ei = alloc_inode_sb(sb, fat_inode_cachep, GFP_NOFS);749 if (!ei)750 return NULL;751 752 init_rwsem(&ei->truncate_lock);753 /* Zeroing to allow iput() even if partial initialized inode. */754 ei->mmu_private = 0;755 ei->i_start = 0;756 ei->i_logstart = 0;757 ei->i_attrs = 0;758 ei->i_pos = 0;759 ei->i_crtime.tv_sec = 0;760 ei->i_crtime.tv_nsec = 0;761 762 return &ei->vfs_inode;763}764 765static void fat_free_inode(struct inode *inode)766{767 kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));768}769 770static void init_once(void *foo)771{772 struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;773 774 spin_lock_init(&ei->cache_lru_lock);775 ei->nr_caches = 0;776 ei->cache_valid_id = FAT_CACHE_VALID + 1;777 INIT_LIST_HEAD(&ei->cache_lru);778 INIT_HLIST_NODE(&ei->i_fat_hash);779 INIT_HLIST_NODE(&ei->i_dir_hash);780 inode_init_once(&ei->vfs_inode);781}782 783static int __init fat_init_inodecache(void)784{785 fat_inode_cachep = kmem_cache_create("fat_inode_cache",786 sizeof(struct msdos_inode_info),787 0, (SLAB_RECLAIM_ACCOUNT|788 SLAB_ACCOUNT),789 init_once);790 if (fat_inode_cachep == NULL)791 return -ENOMEM;792 return 0;793}794 795static void __exit fat_destroy_inodecache(void)796{797 /*798 * Make sure all delayed rcu free inodes are flushed before we799 * destroy cache.800 */801 rcu_barrier();802 kmem_cache_destroy(fat_inode_cachep);803}804 805int fat_reconfigure(struct fs_context *fc)806{807 bool new_rdonly;808 struct super_block *sb = fc->root->d_sb;809 struct msdos_sb_info *sbi = MSDOS_SB(sb);810 fc->sb_flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);811 812 sync_filesystem(sb);813 814 /* make sure we update state on remount. */815 new_rdonly = fc->sb_flags & SB_RDONLY;816 if (new_rdonly != sb_rdonly(sb)) {817 if (new_rdonly)818 fat_set_state(sb, 0, 0);819 else820 fat_set_state(sb, 1, 1);821 }822 return 0;823}824EXPORT_SYMBOL_GPL(fat_reconfigure);825 826static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)827{828 struct super_block *sb = dentry->d_sb;829 struct msdos_sb_info *sbi = MSDOS_SB(sb);830 u64 id = huge_encode_dev(sb->s_bdev->bd_dev);831 832 /* If the count of free cluster is still unknown, counts it here. */833 if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {834 int err = fat_count_free_clusters(dentry->d_sb);835 if (err)836 return err;837 }838 839 buf->f_type = dentry->d_sb->s_magic;840 buf->f_bsize = sbi->cluster_size;841 buf->f_blocks = sbi->max_cluster - FAT_START_ENT;842 buf->f_bfree = sbi->free_clusters;843 buf->f_bavail = sbi->free_clusters;844 buf->f_fsid = u64_to_fsid(id);845 buf->f_namelen =846 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;847 848 return 0;849}850 851static int __fat_write_inode(struct inode *inode, int wait)852{853 struct super_block *sb = inode->i_sb;854 struct msdos_sb_info *sbi = MSDOS_SB(sb);855 struct buffer_head *bh;856 struct msdos_dir_entry *raw_entry;857 struct timespec64 mtime;858 loff_t i_pos;859 sector_t blocknr;860 int err, offset;861 862 if (inode->i_ino == MSDOS_ROOT_INO)863 return 0;864 865retry:866 i_pos = fat_i_pos_read(sbi, inode);867 if (!i_pos)868 return 0;869 870 fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);871 bh = sb_bread(sb, blocknr);872 if (!bh) {873 fat_msg(sb, KERN_ERR, "unable to read inode block "874 "for updating (i_pos %lld)", i_pos);875 return -EIO;876 }877 spin_lock(&sbi->inode_hash_lock);878 if (i_pos != MSDOS_I(inode)->i_pos) {879 spin_unlock(&sbi->inode_hash_lock);880 brelse(bh);881 goto retry;882 }883 884 raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];885 if (S_ISDIR(inode->i_mode))886 raw_entry->size = 0;887 else888 raw_entry->size = cpu_to_le32(inode->i_size);889 raw_entry->attr = fat_make_attrs(inode);890 fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);891 mtime = inode_get_mtime(inode);892 fat_time_unix2fat(sbi, &mtime, &raw_entry->time,893 &raw_entry->date, NULL);894 if (sbi->options.isvfat) {895 struct timespec64 ts = inode_get_atime(inode);896 __le16 atime;897 898 fat_time_unix2fat(sbi, &ts, &atime, &raw_entry->adate, NULL);899 fat_time_unix2fat(sbi, &MSDOS_I(inode)->i_crtime, &raw_entry->ctime,900 &raw_entry->cdate, &raw_entry->ctime_cs);901 }902 spin_unlock(&sbi->inode_hash_lock);903 mark_buffer_dirty(bh);904 err = 0;905 if (wait)906 err = sync_dirty_buffer(bh);907 brelse(bh);908 return err;909}910 911static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)912{913 int err;914 915 if (inode->i_ino == MSDOS_FSINFO_INO) {916 struct super_block *sb = inode->i_sb;917 918 mutex_lock(&MSDOS_SB(sb)->s_lock);919 err = fat_clusters_flush(sb);920 mutex_unlock(&MSDOS_SB(sb)->s_lock);921 } else922 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);923 924 return err;925}926 927int fat_sync_inode(struct inode *inode)928{929 return __fat_write_inode(inode, 1);930}931 932EXPORT_SYMBOL_GPL(fat_sync_inode);933 934static int fat_show_options(struct seq_file *m, struct dentry *root);935static const struct super_operations fat_sops = {936 .alloc_inode = fat_alloc_inode,937 .free_inode = fat_free_inode,938 .write_inode = fat_write_inode,939 .evict_inode = fat_evict_inode,940 .put_super = fat_put_super,941 .statfs = fat_statfs,942 .show_options = fat_show_options,943};944 945static int fat_show_options(struct seq_file *m, struct dentry *root)946{947 struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);948 struct fat_mount_options *opts = &sbi->options;949 int isvfat = opts->isvfat;950 951 if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))952 seq_printf(m, ",uid=%u",953 from_kuid_munged(&init_user_ns, opts->fs_uid));954 if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))955 seq_printf(m, ",gid=%u",956 from_kgid_munged(&init_user_ns, opts->fs_gid));957 seq_printf(m, ",fmask=%04o", opts->fs_fmask);958 seq_printf(m, ",dmask=%04o", opts->fs_dmask);959 if (opts->allow_utime)960 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);961 if (sbi->nls_disk)962 /* strip "cp" prefix from displayed option */963 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);964 if (isvfat) {965 if (sbi->nls_io)966 seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);967 968 switch (opts->shortname) {969 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:970 seq_puts(m, ",shortname=win95");971 break;972 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:973 seq_puts(m, ",shortname=winnt");974 break;975 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:976 seq_puts(m, ",shortname=mixed");977 break;978 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:979 seq_puts(m, ",shortname=lower");980 break;981 default:982 seq_puts(m, ",shortname=unknown");983 break;984 }985 }986 if (opts->name_check != 'n')987 seq_printf(m, ",check=%c", opts->name_check);988 if (opts->usefree)989 seq_puts(m, ",usefree");990 if (opts->quiet)991 seq_puts(m, ",quiet");992 if (opts->showexec)993 seq_puts(m, ",showexec");994 if (opts->sys_immutable)995 seq_puts(m, ",sys_immutable");996 if (!isvfat) {997 if (opts->dotsOK)998 seq_puts(m, ",dotsOK=yes");999 if (opts->nocase)1000 seq_puts(m, ",nocase");1001 } else {1002 if (opts->utf8)1003 seq_puts(m, ",utf8");1004 if (opts->unicode_xlate)1005 seq_puts(m, ",uni_xlate");1006 if (!opts->numtail)1007 seq_puts(m, ",nonumtail");1008 if (opts->rodir)1009 seq_puts(m, ",rodir");1010 }1011 if (opts->flush)1012 seq_puts(m, ",flush");1013 if (opts->tz_set) {1014 if (opts->time_offset)1015 seq_printf(m, ",time_offset=%d", opts->time_offset);1016 else1017 seq_puts(m, ",tz=UTC");1018 }1019 if (opts->errors == FAT_ERRORS_CONT)1020 seq_puts(m, ",errors=continue");1021 else if (opts->errors == FAT_ERRORS_PANIC)1022 seq_puts(m, ",errors=panic");1023 else1024 seq_puts(m, ",errors=remount-ro");1025 if (opts->nfs == FAT_NFS_NOSTALE_RO)1026 seq_puts(m, ",nfs=nostale_ro");1027 else if (opts->nfs)1028 seq_puts(m, ",nfs=stale_rw");1029 if (opts->discard)1030 seq_puts(m, ",discard");1031 if (opts->dos1xfloppy)1032 seq_puts(m, ",dos1xfloppy");1033 1034 return 0;1035}1036 1037enum {1038 Opt_check, Opt_uid, Opt_gid, Opt_umask, Opt_dmask, Opt_fmask,1039 Opt_allow_utime, Opt_codepage, Opt_usefree, Opt_nocase, Opt_quiet,1040 Opt_showexec, Opt_debug, Opt_immutable, Opt_dots, Opt_dotsOK,1041 Opt_charset, Opt_shortname, Opt_utf8, Opt_utf8_bool,1042 Opt_uni_xl, Opt_uni_xl_bool, Opt_nonumtail, Opt_nonumtail_bool,1043 Opt_obsolete, Opt_flush, Opt_tz, Opt_rodir, Opt_errors, Opt_discard,1044 Opt_nfs, Opt_nfs_enum, Opt_time_offset, Opt_dos1xfloppy,1045};1046 1047static const struct constant_table fat_param_check[] = {1048 {"relaxed", 'r'},1049 {"r", 'r'},1050 {"strict", 's'},1051 {"s", 's'},1052 {"normal", 'n'},1053 {"n", 'n'},1054 {}1055};1056 1057static const struct constant_table fat_param_tz[] = {1058 {"UTC", 0},1059 {}1060};1061 1062static const struct constant_table fat_param_errors[] = {1063 {"continue", FAT_ERRORS_CONT},1064 {"panic", FAT_ERRORS_PANIC},1065 {"remount-ro", FAT_ERRORS_RO},1066 {}1067};1068 1069 1070static const struct constant_table fat_param_nfs[] = {1071 {"stale_rw", FAT_NFS_STALE_RW},1072 {"nostale_ro", FAT_NFS_NOSTALE_RO},1073 {}1074};1075 1076/*1077 * These are all obsolete but we still reject invalid options.1078 * The corresponding values are therefore meaningless.1079 */1080static const struct constant_table fat_param_conv[] = {1081 {"binary", 0},1082 {"text", 0},1083 {"auto", 0},1084 {"b", 0},1085 {"t", 0},1086 {"a", 0},1087 {}1088};1089 1090/* Core options. See below for vfat and msdos extras */1091const struct fs_parameter_spec fat_param_spec[] = {1092 fsparam_enum ("check", Opt_check, fat_param_check),1093 fsparam_uid ("uid", Opt_uid),1094 fsparam_gid ("gid", Opt_gid),1095 fsparam_u32oct ("umask", Opt_umask),1096 fsparam_u32oct ("dmask", Opt_dmask),1097 fsparam_u32oct ("fmask", Opt_fmask),1098 fsparam_u32oct ("allow_utime", Opt_allow_utime),1099 fsparam_u32 ("codepage", Opt_codepage),1100 fsparam_flag ("usefree", Opt_usefree),1101 fsparam_flag ("nocase", Opt_nocase),1102 fsparam_flag ("quiet", Opt_quiet),1103 fsparam_flag ("showexec", Opt_showexec),1104 fsparam_flag ("debug", Opt_debug),1105 fsparam_flag ("sys_immutable", Opt_immutable),1106 fsparam_flag ("flush", Opt_flush),1107 fsparam_enum ("tz", Opt_tz, fat_param_tz),1108 fsparam_s32 ("time_offset", Opt_time_offset),1109 fsparam_enum ("errors", Opt_errors, fat_param_errors),1110 fsparam_flag ("discard", Opt_discard),1111 fsparam_flag ("nfs", Opt_nfs),1112 fsparam_enum ("nfs", Opt_nfs_enum, fat_param_nfs),1113 fsparam_flag ("dos1xfloppy", Opt_dos1xfloppy),1114 __fsparam(fs_param_is_enum, "conv",1115 Opt_obsolete, fs_param_deprecated, fat_param_conv),1116 __fsparam(fs_param_is_u32, "fat",1117 Opt_obsolete, fs_param_deprecated, NULL),1118 __fsparam(fs_param_is_u32, "blocksize",1119 Opt_obsolete, fs_param_deprecated, NULL),1120 __fsparam(fs_param_is_string, "cvf_format",1121 Opt_obsolete, fs_param_deprecated, NULL),1122 __fsparam(fs_param_is_string, "cvf_options",1123 Opt_obsolete, fs_param_deprecated, NULL),1124 __fsparam(NULL, "posix",1125 Opt_obsolete, fs_param_deprecated, NULL),1126 {}1127};1128EXPORT_SYMBOL_GPL(fat_param_spec);1129 1130static const struct fs_parameter_spec msdos_param_spec[] = {1131 fsparam_flag_no ("dots", Opt_dots),1132 fsparam_bool ("dotsOK", Opt_dotsOK),1133 {}1134};1135 1136static const struct constant_table fat_param_shortname[] = {1137 {"lower", VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95},1138 {"win95", VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95},1139 {"winnt", VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT},1140 {"mixed", VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95},1141 {}1142};1143 1144static const struct fs_parameter_spec vfat_param_spec[] = {1145 fsparam_string ("iocharset", Opt_charset),1146 fsparam_enum ("shortname", Opt_shortname, fat_param_shortname),1147 fsparam_flag ("utf8", Opt_utf8),1148 fsparam_bool ("utf8", Opt_utf8_bool),1149 fsparam_flag ("uni_xlate", Opt_uni_xl),1150 fsparam_bool ("uni_xlate", Opt_uni_xl_bool),1151 fsparam_flag ("nonumtail", Opt_nonumtail),1152 fsparam_bool ("nonumtail", Opt_nonumtail_bool),1153 fsparam_flag ("rodir", Opt_rodir),1154 {}1155};1156 1157int fat_parse_param(struct fs_context *fc, struct fs_parameter *param,1158 bool is_vfat)1159{1160 struct fat_mount_options *opts = fc->fs_private;1161 struct fs_parse_result result;1162 int opt;1163 1164 /* remount options have traditionally been ignored */1165 if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE)1166 return 0;1167 1168 opt = fs_parse(fc, fat_param_spec, param, &result);1169 /* If option not found in fat_param_spec, try vfat/msdos options */1170 if (opt == -ENOPARAM) {1171 if (is_vfat)1172 opt = fs_parse(fc, vfat_param_spec, param, &result);1173 else1174 opt = fs_parse(fc, msdos_param_spec, param, &result);1175 }1176 1177 if (opt < 0)1178 return opt;1179 1180 switch (opt) {1181 case Opt_check:1182 opts->name_check = result.uint_32;1183 break;1184 case Opt_usefree:1185 opts->usefree = 1;1186 break;1187 case Opt_nocase:1188 if (!is_vfat)1189 opts->nocase = 1;1190 else {1191 /* for backward compatibility */1192 opts->shortname = VFAT_SFN_DISPLAY_WIN951193 | VFAT_SFN_CREATE_WIN95;1194 }1195 break;1196 case Opt_quiet:1197 opts->quiet = 1;1198 break;1199 case Opt_showexec:1200 opts->showexec = 1;1201 break;1202 case Opt_debug:1203 opts->debug = 1;1204 break;1205 case Opt_immutable:1206 opts->sys_immutable = 1;1207 break;1208 case Opt_uid:1209 opts->fs_uid = result.uid;1210 break;1211 case Opt_gid:1212 opts->fs_gid = result.gid;1213 break;1214 case Opt_umask:1215 opts->fs_fmask = opts->fs_dmask = result.uint_32;1216 break;1217 case Opt_dmask:1218 opts->fs_dmask = result.uint_32;1219 break;1220 case Opt_fmask:1221 opts->fs_fmask = result.uint_32;1222 break;1223 case Opt_allow_utime:1224 opts->allow_utime = result.uint_32 & (S_IWGRP | S_IWOTH);1225 break;1226 case Opt_codepage:1227 opts->codepage = result.uint_32;1228 break;1229 case Opt_flush:1230 opts->flush = 1;1231 break;1232 case Opt_time_offset:1233 /*1234 * GMT+-12 zones may have DST corrections so at least1235 * 13 hours difference is needed. Make the limit 241236 * just in case someone invents something unusual.1237 */1238 if (result.int_32 < -24 * 60 || result.int_32 > 24 * 60)1239 return -EINVAL;1240 opts->tz_set = 1;1241 opts->time_offset = result.int_32;1242 break;1243 case Opt_tz:1244 opts->tz_set = 1;1245 opts->time_offset = result.uint_32;1246 break;1247 case Opt_errors:1248 opts->errors = result.uint_32;1249 break;1250 case Opt_nfs:1251 opts->nfs = FAT_NFS_STALE_RW;1252 break;1253 case Opt_nfs_enum:1254 opts->nfs = result.uint_32;1255 break;1256 case Opt_dos1xfloppy:1257 opts->dos1xfloppy = 1;1258 break;1259 1260 /* msdos specific */1261 case Opt_dots: /* dots / nodots */1262 opts->dotsOK = !result.negated;1263 break;1264 case Opt_dotsOK: /* dotsOK = yes/no */1265 opts->dotsOK = result.boolean;1266 break;1267 1268 /* vfat specific */1269 case Opt_charset:1270 fat_reset_iocharset(opts);1271 opts->iocharset = param->string;1272 param->string = NULL; /* Steal string */1273 break;1274 case Opt_shortname:1275 opts->shortname = result.uint_32;1276 break;1277 case Opt_utf8:1278 opts->utf8 = 1;1279 break;1280 case Opt_utf8_bool:1281 opts->utf8 = result.boolean;1282 break;1283 case Opt_uni_xl:1284 opts->unicode_xlate = 1;1285 break;1286 case Opt_uni_xl_bool:1287 opts->unicode_xlate = result.boolean;1288 break;1289 case Opt_nonumtail:1290 opts->numtail = 0; /* negated option */1291 break;1292 case Opt_nonumtail_bool:1293 opts->numtail = !result.boolean; /* negated option */1294 break;1295 case Opt_rodir:1296 opts->rodir = 1;1297 break;1298 case Opt_discard:1299 opts->discard = 1;1300 break;1301 1302 /* obsolete mount options */1303 case Opt_obsolete:1304 printk(KERN_INFO "FAT-fs: \"%s\" option is obsolete, "1305 "not supported now", param->key);1306 break;1307 default:1308 return -EINVAL;1309 }1310 1311 return 0;1312}1313EXPORT_SYMBOL_GPL(fat_parse_param);1314 1315static int fat_read_root(struct inode *inode)1316{1317 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);1318 int error;1319 1320 MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;1321 inode->i_uid = sbi->options.fs_uid;1322 inode->i_gid = sbi->options.fs_gid;1323 inode_inc_iversion(inode);1324 inode->i_generation = 0;1325 inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);1326 inode->i_op = sbi->dir_ops;1327 inode->i_fop = &fat_dir_operations;1328 if (is_fat32(sbi)) {1329 MSDOS_I(inode)->i_start = sbi->root_cluster;1330 error = fat_calc_dir_size(inode);1331 if (error < 0)1332 return error;1333 } else {1334 MSDOS_I(inode)->i_start = 0;1335 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);1336 }1337 inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))1338 & ~((loff_t)sbi->cluster_size - 1)) >> 9;1339 MSDOS_I(inode)->i_logstart = 0;1340 MSDOS_I(inode)->mmu_private = inode->i_size;1341 1342 fat_save_attrs(inode, ATTR_DIR);1343 inode_set_mtime_to_ts(inode,1344 inode_set_atime_to_ts(inode, inode_set_ctime(inode, 0, 0)));1345 set_nlink(inode, fat_subdirs(inode)+2);1346 1347 return 0;1348}1349 1350static unsigned long calc_fat_clusters(struct super_block *sb)1351{1352 struct msdos_sb_info *sbi = MSDOS_SB(sb);1353 1354 /* Divide first to avoid overflow */1355 if (!is_fat12(sbi)) {1356 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;1357 return ent_per_sec * sbi->fat_length;1358 }1359 1360 return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;1361}1362 1363static bool fat_bpb_is_zero(struct fat_boot_sector *b)1364{1365 if (get_unaligned_le16(&b->sector_size))1366 return false;1367 if (b->sec_per_clus)1368 return false;1369 if (b->reserved)1370 return false;1371 if (b->fats)1372 return false;1373 if (get_unaligned_le16(&b->dir_entries))1374 return false;1375 if (get_unaligned_le16(&b->sectors))1376 return false;1377 if (b->media)1378 return false;1379 if (b->fat_length)1380 return false;1381 if (b->secs_track)1382 return false;1383 if (b->heads)1384 return false;1385 return true;1386}1387 1388static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,1389 int silent, struct fat_bios_param_block *bpb)1390{1391 int error = -EINVAL;1392 1393 /* Read in BPB ... */1394 memset(bpb, 0, sizeof(*bpb));1395 bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);1396 bpb->fat_sec_per_clus = b->sec_per_clus;1397 bpb->fat_reserved = le16_to_cpu(b->reserved);1398 bpb->fat_fats = b->fats;1399 bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);1400 bpb->fat_sectors = get_unaligned_le16(&b->sectors);1401 bpb->fat_fat_length = le16_to_cpu(b->fat_length);1402 bpb->fat_total_sect = le32_to_cpu(b->total_sect);1403 1404 bpb->fat16_state = b->fat16.state;1405 bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);1406 1407 bpb->fat32_length = le32_to_cpu(b->fat32.length);1408 bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);1409 bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);1410 bpb->fat32_state = b->fat32.state;1411 bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);1412 1413 /* Validate this looks like a FAT filesystem BPB */1414 if (!bpb->fat_reserved) {1415 if (!silent)1416 fat_msg(sb, KERN_ERR,1417 "bogus number of reserved sectors");1418 goto out;1419 }1420 if (!bpb->fat_fats) {1421 if (!silent)1422 fat_msg(sb, KERN_ERR, "bogus number of FAT structure");1423 goto out;1424 }1425 1426 /*1427 * Earlier we checked here that b->secs_track and b->head are nonzero,1428 * but it turns out valid FAT filesystems can have zero there.1429 */1430 1431 if (!fat_valid_media(b->media)) {1432 if (!silent)1433 fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",1434 (unsigned)b->media);1435 goto out;1436 }1437 1438 if (!is_power_of_2(bpb->fat_sector_size)1439 || (bpb->fat_sector_size < 512)1440 || (bpb->fat_sector_size > 4096)) {1441 if (!silent)1442 fat_msg(sb, KERN_ERR, "bogus logical sector size %u",1443 (unsigned)bpb->fat_sector_size);1444 goto out;1445 }1446 1447 if (!is_power_of_2(bpb->fat_sec_per_clus)) {1448 if (!silent)1449 fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",1450 (unsigned)bpb->fat_sec_per_clus);1451 goto out;1452 }1453 1454 if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {1455 if (!silent)1456 fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");1457 goto out;1458 }1459 1460 error = 0;1461 1462out:1463 return error;1464}1465 1466static int fat_read_static_bpb(struct super_block *sb,1467 struct fat_boot_sector *b, int silent,1468 struct fat_bios_param_block *bpb)1469{1470 static const char *notdos1x = "This doesn't look like a DOS 1.x volume";1471 sector_t bd_sects = bdev_nr_sectors(sb->s_bdev);1472 struct fat_floppy_defaults *fdefaults = NULL;1473 int error = -EINVAL;1474 unsigned i;1475 1476 /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */1477 if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {1478 if (!silent)1479 fat_msg(sb, KERN_ERR,1480 "%s; no bootstrapping code", notdos1x);1481 goto out;1482 }1483 1484 /*1485 * If any value in this region is non-zero, it isn't archaic1486 * DOS.1487 */1488 if (!fat_bpb_is_zero(b)) {1489 if (!silent)1490 fat_msg(sb, KERN_ERR,1491 "%s; DOS 2.x BPB is non-zero", notdos1x);1492 goto out;1493 }1494 1495 for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {1496 if (floppy_defaults[i].nr_sectors == bd_sects) {1497 fdefaults = &floppy_defaults[i];1498 break;1499 }1500 }1501 1502 if (fdefaults == NULL) {1503 if (!silent)1504 fat_msg(sb, KERN_WARNING,1505 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",1506 (u64)bd_sects);1507 goto out;1508 }1509 1510 if (!silent)1511 fat_msg(sb, KERN_INFO,1512 "This looks like a DOS 1.x volume; assuming default BPB values");1513 1514 memset(bpb, 0, sizeof(*bpb));1515 bpb->fat_sector_size = SECTOR_SIZE;1516 bpb->fat_sec_per_clus = fdefaults->sec_per_clus;1517 bpb->fat_reserved = 1;1518 bpb->fat_fats = 2;1519 bpb->fat_dir_entries = fdefaults->dir_entries;1520 bpb->fat_sectors = fdefaults->nr_sectors;1521 bpb->fat_fat_length = fdefaults->fat_length;1522 1523 error = 0;1524 1525out:1526 return error;1527}1528 1529/*1530 * Read the super block of an MS-DOS FS.1531 */1532int fat_fill_super(struct super_block *sb, struct fs_context *fc,1533 void (*setup)(struct super_block *))1534{1535 struct fat_mount_options *opts = fc->fs_private;1536 int silent = fc->sb_flags & SB_SILENT;1537 struct inode *root_inode = NULL, *fat_inode = NULL;1538 struct inode *fsinfo_inode = NULL;1539 struct buffer_head *bh;1540 struct fat_bios_param_block bpb;1541 struct msdos_sb_info *sbi;1542 u16 logical_sector_size;1543 u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;1544 long error;1545 char buf[50];1546 struct timespec64 ts;1547 1548 /*1549 * GFP_KERNEL is ok here, because while we do hold the1550 * superblock lock, memory pressure can't call back into1551 * the filesystem, since we're only just about to mount1552 * it and have no inodes etc active!1553 */1554 sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);1555 if (!sbi)1556 return -ENOMEM;1557 sb->s_fs_info = sbi;1558 1559 sb->s_flags |= SB_NODIRATIME;1560 sb->s_magic = MSDOS_SUPER_MAGIC;1561 sb->s_op = &fat_sops;1562 sb->s_export_op = &fat_export_ops;1563 /*1564 * fat timestamps are complex and truncated by fat itself, so1565 * we set 1 here to be fast1566 */1567 sb->s_time_gran = 1;1568 mutex_init(&sbi->nfs_build_inode_lock);1569 ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,1570 DEFAULT_RATELIMIT_BURST);1571 1572 /* UTF-8 doesn't provide FAT semantics */1573 if (!strcmp(opts->iocharset, "utf8")) {1574 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"1575 " for FAT filesystems, filesystem will be"1576 " case sensitive!");1577 }1578 1579 /* If user doesn't specify allow_utime, it's initialized from dmask. */1580 if (opts->allow_utime == (unsigned short)-1)1581 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);1582 if (opts->unicode_xlate)1583 opts->utf8 = 0;1584 if (opts->nfs == FAT_NFS_NOSTALE_RO) {1585 sb->s_flags |= SB_RDONLY;1586 sb->s_export_op = &fat_export_ops_nostale;1587 }1588 1589 /* Apply parsed options to sbi (structure copy) */1590 sbi->options = *opts;1591 /* Transfer ownership of iocharset to sbi->options */1592 opts->iocharset = NULL;1593 1594 setup(sb); /* flavour-specific stuff that needs options */1595 1596 error = -EIO;1597 sb_min_blocksize(sb, 512);1598 bh = sb_bread(sb, 0);1599 if (bh == NULL) {1600 fat_msg(sb, KERN_ERR, "unable to read boot sector");1601 goto out_fail;1602 }1603 1604 error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,1605 &bpb);1606 if (error == -EINVAL && sbi->options.dos1xfloppy)1607 error = fat_read_static_bpb(sb,1608 (struct fat_boot_sector *)bh->b_data, silent, &bpb);1609 brelse(bh);1610 1611 if (error == -EINVAL)1612 goto out_invalid;1613 else if (error)1614 goto out_fail;1615 1616 logical_sector_size = bpb.fat_sector_size;1617 sbi->sec_per_clus = bpb.fat_sec_per_clus;1618 1619 error = -EIO;1620 if (logical_sector_size < sb->s_blocksize) {1621 fat_msg(sb, KERN_ERR, "logical sector size too small for device"1622 " (logical sector size = %u)", logical_sector_size);1623 goto out_fail;1624 }1625 1626 if (logical_sector_size > sb->s_blocksize) {1627 struct buffer_head *bh_resize;1628 1629 if (!sb_set_blocksize(sb, logical_sector_size)) {1630 fat_msg(sb, KERN_ERR, "unable to set blocksize %u",1631 logical_sector_size);1632 goto out_fail;1633 }1634 1635 /* Verify that the larger boot sector is fully readable */1636 bh_resize = sb_bread(sb, 0);1637 if (bh_resize == NULL) {1638 fat_msg(sb, KERN_ERR, "unable to read boot sector"1639 " (logical sector size = %lu)",1640 sb->s_blocksize);1641 goto out_fail;1642 }1643 brelse(bh_resize);1644 }1645 1646 mutex_init(&sbi->s_lock);1647 sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;1648 sbi->cluster_bits = ffs(sbi->cluster_size) - 1;1649 sbi->fats = bpb.fat_fats;1650 sbi->fat_bits = 0; /* Don't know yet */1651 sbi->fat_start = bpb.fat_reserved;1652 sbi->fat_length = bpb.fat_fat_length;1653 sbi->root_cluster = 0;1654 sbi->free_clusters = -1; /* Don't know yet */1655 sbi->free_clus_valid = 0;1656 sbi->prev_free = FAT_START_ENT;1657 sb->s_maxbytes = 0xffffffff;1658 fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);1659 sb->s_time_min = ts.tv_sec;1660 1661 fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),1662 cpu_to_le16(FAT_DATE_MAX), 0);1663 sb->s_time_max = ts.tv_sec;1664 1665 if (!sbi->fat_length && bpb.fat32_length) {1666 struct fat_boot_fsinfo *fsinfo;1667 struct buffer_head *fsinfo_bh;1668 1669 /* Must be FAT32 */1670 sbi->fat_bits = 32;1671 sbi->fat_length = bpb.fat32_length;1672 sbi->root_cluster = bpb.fat32_root_cluster;1673 1674 /* MC - if info_sector is 0, don't multiply by 0 */1675 sbi->fsinfo_sector = bpb.fat32_info_sector;1676 if (sbi->fsinfo_sector == 0)1677 sbi->fsinfo_sector = 1;1678 1679 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);1680 if (fsinfo_bh == NULL) {1681 fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"1682 " (sector = %lu)", sbi->fsinfo_sector);1683 goto out_fail;1684 }1685 1686 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;1687 if (!IS_FSINFO(fsinfo)) {1688 fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "1689 "0x%08x, 0x%08x (sector = %lu)",1690 le32_to_cpu(fsinfo->signature1),1691 le32_to_cpu(fsinfo->signature2),1692 sbi->fsinfo_sector);1693 } else {1694 if (sbi->options.usefree)1695 sbi->free_clus_valid = 1;1696 sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);1697 sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);1698 }1699 1700 brelse(fsinfo_bh);1701 }1702 1703 /* interpret volume ID as a little endian 32 bit integer */1704 if (is_fat32(sbi))1705 sbi->vol_id = bpb.fat32_vol_id;1706 else /* fat 16 or 12 */1707 sbi->vol_id = bpb.fat16_vol_id;1708 1709 __le32 vol_id_le = cpu_to_le32(sbi->vol_id);1710 super_set_uuid(sb, (void *) &vol_id_le, sizeof(vol_id_le));1711 1712 sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);1713 sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;1714 1715 sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;1716 sbi->dir_entries = bpb.fat_dir_entries;1717 if (sbi->dir_entries & (sbi->dir_per_block - 1)) {1718 if (!silent)1719 fat_msg(sb, KERN_ERR, "bogus number of directory entries"1720 " (%u)", sbi->dir_entries);1721 goto out_invalid;1722 }1723 1724 rootdir_sectors = sbi->dir_entries1725 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;1726 sbi->data_start = sbi->dir_start + rootdir_sectors;1727 total_sectors = bpb.fat_sectors;1728 if (total_sectors == 0)1729 total_sectors = bpb.fat_total_sect;1730 1731 total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;1732 1733 if (!is_fat32(sbi))1734 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;1735 1736 /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */1737 if (is_fat32(sbi))1738 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;1739 else /* fat 16 or 12 */1740 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;1741 1742 /* check that FAT table does not overflow */1743 fat_clusters = calc_fat_clusters(sb);1744 total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);1745 if (total_clusters > max_fat(sb)) {1746 if (!silent)1747 fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",1748 total_clusters);1749 goto out_invalid;1750 }1751 1752 sbi->max_cluster = total_clusters + FAT_START_ENT;1753 /* check the free_clusters, it's not necessarily correct */1754 if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)1755 sbi->free_clusters = -1;1756 /* check the prev_free, it's not necessarily correct */1757 sbi->prev_free %= sbi->max_cluster;1758 if (sbi->prev_free < FAT_START_ENT)1759 sbi->prev_free = FAT_START_ENT;1760 1761 /* set up enough so that it can read an inode */1762 fat_hash_init(sb);1763 dir_hash_init(sb);1764 fat_ent_access_init(sb);1765 1766 /*1767 * The low byte of the first FAT entry must have the same value as1768 * the media field of the boot sector. But in real world, too many1769 * devices are writing wrong values. So, removed that validity check.1770 *1771 * The removed check compared the first FAT entry to a value dependent1772 * on the media field like this:1773 * == (0x0F00 | media), for FAT121774 * == (0XFF00 | media), for FAT161775 * == (0x0FFFFF | media), for FAT321776 */1777 1778 error = -EINVAL;1779 sprintf(buf, "cp%d", sbi->options.codepage);1780 sbi->nls_disk = load_nls(buf);1781 if (!sbi->nls_disk) {1782 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);1783 goto out_fail;1784 }1785 1786 /* FIXME: utf8 is using iocharset for upper/lower conversion */1787 if (sbi->options.isvfat) {1788 sbi->nls_io = load_nls(sbi->options.iocharset);1789 if (!sbi->nls_io) {1790 fat_msg(sb, KERN_ERR, "IO charset %s not found",1791 sbi->options.iocharset);1792 goto out_fail;1793 }1794 }1795 1796 error = -ENOMEM;1797 fat_inode = new_inode(sb);1798 if (!fat_inode)1799 goto out_fail;1800 sbi->fat_inode = fat_inode;1801 1802 fsinfo_inode = new_inode(sb);1803 if (!fsinfo_inode)1804 goto out_fail;1805 fsinfo_inode->i_ino = MSDOS_FSINFO_INO;1806 sbi->fsinfo_inode = fsinfo_inode;1807 insert_inode_hash(fsinfo_inode);1808 1809 root_inode = new_inode(sb);1810 if (!root_inode)1811 goto out_fail;1812 root_inode->i_ino = MSDOS_ROOT_INO;1813 inode_set_iversion(root_inode, 1);1814 error = fat_read_root(root_inode);1815 if (error < 0) {1816 iput(root_inode);1817 goto out_fail;1818 }1819 error = -ENOMEM;1820 insert_inode_hash(root_inode);1821 fat_attach(root_inode, 0);1822 sb->s_root = d_make_root(root_inode);1823 if (!sb->s_root) {1824 fat_msg(sb, KERN_ERR, "get root inode failed");1825 goto out_fail;1826 }1827 1828 if (sbi->options.discard && !bdev_max_discard_sectors(sb->s_bdev))1829 fat_msg(sb, KERN_WARNING,1830 "mounting with \"discard\" option, but the device does not support discard");1831 1832 fat_set_state(sb, 1, 0);1833 return 0;1834 1835out_invalid:1836 error = -EINVAL;1837 if (!silent)1838 fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");1839 1840out_fail:1841 iput(fsinfo_inode);1842 iput(fat_inode);1843 unload_nls(sbi->nls_io);1844 unload_nls(sbi->nls_disk);1845 fat_reset_iocharset(&sbi->options);1846 sb->s_fs_info = NULL;1847 kfree(sbi);1848 return error;1849}1850 1851EXPORT_SYMBOL_GPL(fat_fill_super);1852 1853/*1854 * helper function for fat_flush_inodes. This writes both the inode1855 * and the file data blocks, waiting for in flight data blocks before1856 * the start of the call. It does not wait for any io started1857 * during the call1858 */1859static int writeback_inode(struct inode *inode)1860{1861 1862 int ret;1863 1864 /* if we used wait=1, sync_inode_metadata waits for the io for the1865 * inode to finish. So wait=0 is sent down to sync_inode_metadata1866 * and filemap_fdatawrite is used for the data blocks1867 */1868 ret = sync_inode_metadata(inode, 0);1869 if (!ret)1870 ret = filemap_fdatawrite(inode->i_mapping);1871 return ret;1872}1873 1874/*1875 * write data and metadata corresponding to i1 and i2. The io is1876 * started but we do not wait for any of it to finish.1877 *1878 * filemap_flush is used for the block device, so if there is a dirty1879 * page for a block already in flight, we will not wait and start the1880 * io over again1881 */1882int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)1883{1884 int ret = 0;1885 if (!MSDOS_SB(sb)->options.flush)1886 return 0;1887 if (i1)1888 ret = writeback_inode(i1);1889 if (!ret && i2)1890 ret = writeback_inode(i2);1891 if (!ret)1892 ret = sync_blockdev_nowait(sb->s_bdev);1893 return ret;1894}1895EXPORT_SYMBOL_GPL(fat_flush_inodes);1896 1897int fat_init_fs_context(struct fs_context *fc, bool is_vfat)1898{1899 struct fat_mount_options *opts;1900 1901 opts = kzalloc(sizeof(*opts), GFP_KERNEL);1902 if (!opts)1903 return -ENOMEM;1904 1905 opts->isvfat = is_vfat;1906 opts->fs_uid = current_uid();1907 opts->fs_gid = current_gid();1908 opts->fs_fmask = opts->fs_dmask = current_umask();1909 opts->allow_utime = -1;1910 opts->codepage = fat_default_codepage;1911 fat_reset_iocharset(opts);1912 if (is_vfat) {1913 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;1914 opts->rodir = 0;1915 } else {1916 opts->shortname = 0;1917 opts->rodir = 1;1918 }1919 opts->name_check = 'n';1920 opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK = 0;1921 opts->unicode_xlate = 0;1922 opts->numtail = 1;1923 opts->usefree = opts->nocase = 0;1924 opts->tz_set = 0;1925 opts->nfs = 0;1926 opts->errors = FAT_ERRORS_RO;1927 opts->debug = 0;1928 1929 opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;1930 1931 fc->fs_private = opts;1932 /* fc->ops assigned by caller */1933 1934 return 0;1935}1936EXPORT_SYMBOL_GPL(fat_init_fs_context);1937 1938void fat_free_fc(struct fs_context *fc)1939{1940 struct fat_mount_options *opts = fc->fs_private;1941 1942 if (opts->iocharset != fat_default_iocharset)1943 kfree(opts->iocharset);1944 kfree(fc->fs_private);1945}1946EXPORT_SYMBOL_GPL(fat_free_fc);1947 1948static int __init init_fat_fs(void)1949{1950 int err;1951 1952 err = fat_cache_init();1953 if (err)1954 return err;1955 1956 err = fat_init_inodecache();1957 if (err)1958 goto failed;1959 1960 return 0;1961 1962failed:1963 fat_cache_destroy();1964 return err;1965}1966 1967static void __exit exit_fat_fs(void)1968{1969 fat_cache_destroy();1970 fat_destroy_inodecache();1971}1972 1973module_init(init_fat_fs)1974module_exit(exit_fat_fs)1975 1976MODULE_DESCRIPTION("Core FAT filesystem support");1977MODULE_LICENSE("GPL");1978