fat.h (16054B)
1/* SPDX-License-Identifier: GPL-2.0 */ 2#ifndef _FAT_H 3#define _FAT_H 4 5#include <linux/buffer_head.h> 6#include <linux/nls.h> 7#include <linux/hash.h> 8#include <linux/ratelimit.h> 9#include <linux/msdos_fs.h> 10 11/* 12 * vfat shortname flags 13 */ 14#define VFAT_SFN_DISPLAY_LOWER 0x0001 /* convert to lowercase for display */ 15#define VFAT_SFN_DISPLAY_WIN95 0x0002 /* emulate win95 rule for display */ 16#define VFAT_SFN_DISPLAY_WINNT 0x0004 /* emulate winnt rule for display */ 17#define VFAT_SFN_CREATE_WIN95 0x0100 /* emulate win95 rule for create */ 18#define VFAT_SFN_CREATE_WINNT 0x0200 /* emulate winnt rule for create */ 19 20#define FAT_ERRORS_CONT 1 /* ignore error and continue */ 21#define FAT_ERRORS_PANIC 2 /* panic on error */ 22#define FAT_ERRORS_RO 3 /* remount r/o on error */ 23 24#define FAT_NFS_STALE_RW 1 /* NFS RW support, can cause ESTALE */ 25#define FAT_NFS_NOSTALE_RO 2 /* NFS RO support, no ESTALE issue */ 26 27struct fat_mount_options { 28 kuid_t fs_uid; 29 kgid_t fs_gid; 30 unsigned short fs_fmask; 31 unsigned short fs_dmask; 32 unsigned short codepage; /* Codepage for shortname conversions */ 33 int time_offset; /* Offset of timestamps from UTC (in minutes) */ 34 char *iocharset; /* Charset used for filename input/display */ 35 unsigned short shortname; /* flags for shortname display/create rule */ 36 unsigned char name_check; /* r = relaxed, n = normal, s = strict */ 37 unsigned char errors; /* On error: continue, panic, remount-ro */ 38 unsigned char nfs; /* NFS support: nostale_ro, stale_rw */ 39 unsigned short allow_utime;/* permission for setting the [am]time */ 40 unsigned quiet:1, /* set = fake successful chmods and chowns */ 41 showexec:1, /* set = only set x bit for com/exe/bat */ 42 sys_immutable:1, /* set = system files are immutable */ 43 dotsOK:1, /* set = hidden and system files are named '.filename' */ 44 isvfat:1, /* 0=no vfat long filename support, 1=vfat support */ 45 utf8:1, /* Use of UTF-8 character set (Default) */ 46 unicode_xlate:1, /* create escape sequences for unhandled Unicode */ 47 numtail:1, /* Does first alias have a numeric '~1' type tail? */ 48 flush:1, /* write things quickly */ 49 nocase:1, /* Does this need case conversion? 0=need case conversion*/ 50 usefree:1, /* Use free_clusters for FAT32 */ 51 tz_set:1, /* Filesystem timestamps' offset set */ 52 rodir:1, /* allow ATTR_RO for directory */ 53 discard:1, /* Issue discard requests on deletions */ 54 dos1xfloppy:1; /* Assume default BPB for DOS 1.x floppies */ 55}; 56 57#define FAT_HASH_BITS 8 58#define FAT_HASH_SIZE (1UL << FAT_HASH_BITS) 59 60/* 61 * MS-DOS file system in-core superblock data 62 */ 63struct msdos_sb_info { 64 unsigned short sec_per_clus; /* sectors/cluster */ 65 unsigned short cluster_bits; /* log2(cluster_size) */ 66 unsigned int cluster_size; /* cluster size */ 67 unsigned char fats, fat_bits; /* number of FATs, FAT bits (12,16 or 32) */ 68 unsigned short fat_start; 69 unsigned long fat_length; /* FAT start & length (sec.) */ 70 unsigned long dir_start; 71 unsigned short dir_entries; /* root dir start & entries */ 72 unsigned long data_start; /* first data sector */ 73 unsigned long max_cluster; /* maximum cluster number */ 74 unsigned long root_cluster; /* first cluster of the root directory */ 75 unsigned long fsinfo_sector; /* sector number of FAT32 fsinfo */ 76 struct mutex fat_lock; 77 struct mutex nfs_build_inode_lock; 78 struct mutex s_lock; 79 unsigned int prev_free; /* previously allocated cluster number */ 80 unsigned int free_clusters; /* -1 if undefined */ 81 unsigned int free_clus_valid; /* is free_clusters valid? */ 82 struct fat_mount_options options; 83 struct nls_table *nls_disk; /* Codepage used on disk */ 84 struct nls_table *nls_io; /* Charset used for input and display */ 85 const void *dir_ops; /* Opaque; default directory operations */ 86 int dir_per_block; /* dir entries per block */ 87 int dir_per_block_bits; /* log2(dir_per_block) */ 88 unsigned int vol_id; /*volume ID*/ 89 90 int fatent_shift; 91 const struct fatent_operations *fatent_ops; 92 struct inode *fat_inode; 93 struct inode *fsinfo_inode; 94 95 struct ratelimit_state ratelimit; 96 97 spinlock_t inode_hash_lock; 98 struct hlist_head inode_hashtable[FAT_HASH_SIZE]; 99 100 spinlock_t dir_hash_lock; 101 struct hlist_head dir_hashtable[FAT_HASH_SIZE]; 102 103 unsigned int dirty; /* fs state before mount */ 104 struct rcu_head rcu; 105}; 106 107#define FAT_CACHE_VALID 0 /* special case for valid cache */ 108 109/* 110 * MS-DOS file system inode data in memory 111 */ 112struct msdos_inode_info { 113 spinlock_t cache_lru_lock; 114 struct list_head cache_lru; 115 int nr_caches; 116 /* for avoiding the race between fat_free() and fat_get_cluster() */ 117 unsigned int cache_valid_id; 118 119 /* NOTE: mmu_private is 64bits, so must hold ->i_mutex to access */ 120 loff_t mmu_private; /* physically allocated size */ 121 122 int i_start; /* first cluster or 0 */ 123 int i_logstart; /* logical first cluster */ 124 int i_attrs; /* unused attribute bits */ 125 loff_t i_pos; /* on-disk position of directory entry or 0 */ 126 struct hlist_node i_fat_hash; /* hash by i_location */ 127 struct hlist_node i_dir_hash; /* hash by i_logstart */ 128 struct rw_semaphore truncate_lock; /* protect bmap against truncate */ 129 struct timespec64 i_crtime; /* File creation (birth) time */ 130 struct inode vfs_inode; 131}; 132 133struct fat_slot_info { 134 loff_t i_pos; /* on-disk position of directory entry */ 135 loff_t slot_off; /* offset for slot or de start */ 136 int nr_slots; /* number of slots + 1(de) in filename */ 137 struct msdos_dir_entry *de; 138 struct buffer_head *bh; 139}; 140 141static inline struct msdos_sb_info *MSDOS_SB(struct super_block *sb) 142{ 143 return sb->s_fs_info; 144} 145 146/* 147 * Functions that determine the variant of the FAT file system (i.e., 148 * whether this is FAT12, FAT16 or FAT32. 149 */ 150static inline bool is_fat12(const struct msdos_sb_info *sbi) 151{ 152 return sbi->fat_bits == 12; 153} 154 155static inline bool is_fat16(const struct msdos_sb_info *sbi) 156{ 157 return sbi->fat_bits == 16; 158} 159 160static inline bool is_fat32(const struct msdos_sb_info *sbi) 161{ 162 return sbi->fat_bits == 32; 163} 164 165/* Maximum number of clusters */ 166static inline u32 max_fat(struct super_block *sb) 167{ 168 struct msdos_sb_info *sbi = MSDOS_SB(sb); 169 170 return is_fat32(sbi) ? MAX_FAT32 : 171 is_fat16(sbi) ? MAX_FAT16 : MAX_FAT12; 172} 173 174static inline struct msdos_inode_info *MSDOS_I(struct inode *inode) 175{ 176 return container_of(inode, struct msdos_inode_info, vfs_inode); 177} 178 179/* 180 * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to 181 * save ATTR_RO instead of ->i_mode. 182 * 183 * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only 184 * bit, it's just used as flag for app. 185 */ 186static inline int fat_mode_can_hold_ro(struct inode *inode) 187{ 188 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 189 umode_t mask; 190 191 if (S_ISDIR(inode->i_mode)) { 192 if (!sbi->options.rodir) 193 return 0; 194 mask = ~sbi->options.fs_dmask; 195 } else 196 mask = ~sbi->options.fs_fmask; 197 198 if (!(mask & S_IWUGO)) 199 return 0; 200 return 1; 201} 202 203/* Convert attribute bits and a mask to the UNIX mode. */ 204static inline umode_t fat_make_mode(struct msdos_sb_info *sbi, 205 u8 attrs, umode_t mode) 206{ 207 if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir)) 208 mode &= ~S_IWUGO; 209 210 if (attrs & ATTR_DIR) 211 return (mode & ~sbi->options.fs_dmask) | S_IFDIR; 212 else 213 return (mode & ~sbi->options.fs_fmask) | S_IFREG; 214} 215 216/* Return the FAT attribute byte for this inode */ 217static inline u8 fat_make_attrs(struct inode *inode) 218{ 219 u8 attrs = MSDOS_I(inode)->i_attrs; 220 if (S_ISDIR(inode->i_mode)) 221 attrs |= ATTR_DIR; 222 if (fat_mode_can_hold_ro(inode) && !(inode->i_mode & S_IWUGO)) 223 attrs |= ATTR_RO; 224 return attrs; 225} 226 227static inline void fat_save_attrs(struct inode *inode, u8 attrs) 228{ 229 if (fat_mode_can_hold_ro(inode)) 230 MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED; 231 else 232 MSDOS_I(inode)->i_attrs = attrs & (ATTR_UNUSED | ATTR_RO); 233} 234 235static inline unsigned char fat_checksum(const __u8 *name) 236{ 237 unsigned char s = name[0]; 238 s = (s<<7) + (s>>1) + name[1]; s = (s<<7) + (s>>1) + name[2]; 239 s = (s<<7) + (s>>1) + name[3]; s = (s<<7) + (s>>1) + name[4]; 240 s = (s<<7) + (s>>1) + name[5]; s = (s<<7) + (s>>1) + name[6]; 241 s = (s<<7) + (s>>1) + name[7]; s = (s<<7) + (s>>1) + name[8]; 242 s = (s<<7) + (s>>1) + name[9]; s = (s<<7) + (s>>1) + name[10]; 243 return s; 244} 245 246static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus) 247{ 248 return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus 249 + sbi->data_start; 250} 251 252static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi, 253 loff_t i_pos, sector_t *blknr, int *offset) 254{ 255 *blknr = i_pos >> sbi->dir_per_block_bits; 256 *offset = i_pos & (sbi->dir_per_block - 1); 257} 258 259static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi, 260 struct inode *inode) 261{ 262 loff_t i_pos; 263#if BITS_PER_LONG == 32 264 spin_lock(&sbi->inode_hash_lock); 265#endif 266 i_pos = MSDOS_I(inode)->i_pos; 267#if BITS_PER_LONG == 32 268 spin_unlock(&sbi->inode_hash_lock); 269#endif 270 return i_pos; 271} 272 273static inline void fat16_towchar(wchar_t *dst, const __u8 *src, size_t len) 274{ 275#ifdef __BIG_ENDIAN 276 while (len--) { 277 *dst++ = src[0] | (src[1] << 8); 278 src += 2; 279 } 280#else 281 memcpy(dst, src, len * 2); 282#endif 283} 284 285static inline int fat_get_start(const struct msdos_sb_info *sbi, 286 const struct msdos_dir_entry *de) 287{ 288 int cluster = le16_to_cpu(de->start); 289 if (is_fat32(sbi)) 290 cluster |= (le16_to_cpu(de->starthi) << 16); 291 return cluster; 292} 293 294static inline void fat_set_start(struct msdos_dir_entry *de, int cluster) 295{ 296 de->start = cpu_to_le16(cluster); 297 de->starthi = cpu_to_le16(cluster >> 16); 298} 299 300static inline void fatwchar_to16(__u8 *dst, const wchar_t *src, size_t len) 301{ 302#ifdef __BIG_ENDIAN 303 while (len--) { 304 dst[0] = *src & 0x00FF; 305 dst[1] = (*src & 0xFF00) >> 8; 306 dst += 2; 307 src++; 308 } 309#else 310 memcpy(dst, src, len * 2); 311#endif 312} 313 314/* fat/cache.c */ 315extern void fat_cache_inval_inode(struct inode *inode); 316extern int fat_get_cluster(struct inode *inode, int cluster, 317 int *fclus, int *dclus); 318extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector, 319 sector_t last_block, 320 unsigned long *mapped_blocks, sector_t *bmap); 321extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys, 322 unsigned long *mapped_blocks, int create, bool from_bmap); 323 324/* fat/dir.c */ 325extern const struct file_operations fat_dir_operations; 326extern int fat_search_long(struct inode *inode, const unsigned char *name, 327 int name_len, struct fat_slot_info *sinfo); 328extern int fat_dir_empty(struct inode *dir); 329extern int fat_subdirs(struct inode *dir); 330extern int fat_scan(struct inode *dir, const unsigned char *name, 331 struct fat_slot_info *sinfo); 332extern int fat_scan_logstart(struct inode *dir, int i_logstart, 333 struct fat_slot_info *sinfo); 334extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh, 335 struct msdos_dir_entry **de); 336extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts); 337extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots, 338 struct fat_slot_info *sinfo); 339extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo); 340 341/* fat/fatent.c */ 342struct fat_entry { 343 int entry; 344 union { 345 u8 *ent12_p[2]; 346 __le16 *ent16_p; 347 __le32 *ent32_p; 348 } u; 349 int nr_bhs; 350 struct buffer_head *bhs[2]; 351 struct inode *fat_inode; 352}; 353 354static inline void fatent_init(struct fat_entry *fatent) 355{ 356 fatent->nr_bhs = 0; 357 fatent->entry = 0; 358 fatent->u.ent32_p = NULL; 359 fatent->bhs[0] = fatent->bhs[1] = NULL; 360 fatent->fat_inode = NULL; 361} 362 363static inline void fatent_set_entry(struct fat_entry *fatent, int entry) 364{ 365 fatent->entry = entry; 366 fatent->u.ent32_p = NULL; 367} 368 369static inline void fatent_brelse(struct fat_entry *fatent) 370{ 371 int i; 372 fatent->u.ent32_p = NULL; 373 for (i = 0; i < fatent->nr_bhs; i++) 374 brelse(fatent->bhs[i]); 375 fatent->nr_bhs = 0; 376 fatent->bhs[0] = fatent->bhs[1] = NULL; 377 fatent->fat_inode = NULL; 378} 379 380static inline bool fat_valid_entry(struct msdos_sb_info *sbi, int entry) 381{ 382 return FAT_START_ENT <= entry && entry < sbi->max_cluster; 383} 384 385extern void fat_ent_access_init(struct super_block *sb); 386extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent, 387 int entry); 388extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 389 int new, int wait); 390extern int fat_alloc_clusters(struct inode *inode, int *cluster, 391 int nr_cluster); 392extern int fat_free_clusters(struct inode *inode, int cluster); 393extern int fat_count_free_clusters(struct super_block *sb); 394extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range); 395 396/* fat/file.c */ 397extern long fat_generic_ioctl(struct file *filp, unsigned int cmd, 398 unsigned long arg); 399extern const struct file_operations fat_file_operations; 400extern const struct inode_operations fat_file_inode_operations; 401extern int fat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, 402 struct iattr *attr); 403extern void fat_truncate_blocks(struct inode *inode, loff_t offset); 404extern int fat_getattr(struct user_namespace *mnt_userns, 405 const struct path *path, struct kstat *stat, 406 u32 request_mask, unsigned int flags); 407extern int fat_file_fsync(struct file *file, loff_t start, loff_t end, 408 int datasync); 409 410/* fat/inode.c */ 411extern int fat_block_truncate_page(struct inode *inode, loff_t from); 412extern void fat_attach(struct inode *inode, loff_t i_pos); 413extern void fat_detach(struct inode *inode); 414extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos); 415extern struct inode *fat_build_inode(struct super_block *sb, 416 struct msdos_dir_entry *de, loff_t i_pos); 417extern int fat_sync_inode(struct inode *inode); 418extern int fat_fill_super(struct super_block *sb, void *data, int silent, 419 int isvfat, void (*setup)(struct super_block *)); 420extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de); 421 422extern int fat_flush_inodes(struct super_block *sb, struct inode *i1, 423 struct inode *i2); 424static inline unsigned long fat_dir_hash(int logstart) 425{ 426 return hash_32(logstart, FAT_HASH_BITS); 427} 428extern int fat_add_cluster(struct inode *inode); 429 430/* fat/misc.c */ 431extern __printf(3, 4) __cold 432void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...); 433#define fat_fs_error(sb, fmt, args...) \ 434 __fat_fs_error(sb, 1, fmt , ## args) 435#define fat_fs_error_ratelimit(sb, fmt, args...) \ 436 __fat_fs_error(sb, __ratelimit(&MSDOS_SB(sb)->ratelimit), fmt , ## args) 437 438#define FAT_PRINTK_PREFIX "%sFAT-fs (%s): " 439#define fat_msg(sb, level, fmt, args...) \ 440do { \ 441 printk_index_subsys_emit(FAT_PRINTK_PREFIX, level, fmt, ##args);\ 442 _fat_msg(sb, level, fmt, ##args); \ 443} while (0) 444__printf(3, 4) __cold 445void _fat_msg(struct super_block *sb, const char *level, const char *fmt, ...); 446#define fat_msg_ratelimit(sb, level, fmt, args...) \ 447 do { \ 448 if (__ratelimit(&MSDOS_SB(sb)->ratelimit)) \ 449 fat_msg(sb, level, fmt, ## args); \ 450 } while (0) 451extern int fat_clusters_flush(struct super_block *sb); 452extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster); 453extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts, 454 __le16 __time, __le16 __date, u8 time_cs); 455extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts, 456 __le16 *time, __le16 *date, u8 *time_cs); 457extern struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi, 458 const struct timespec64 *ts); 459extern struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi, 460 const struct timespec64 *ts); 461extern int fat_truncate_time(struct inode *inode, struct timespec64 *now, 462 int flags); 463extern int fat_update_time(struct inode *inode, struct timespec64 *now, 464 int flags); 465extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs); 466 467int fat_cache_init(void); 468void fat_cache_destroy(void); 469 470/* fat/nfs.c */ 471extern const struct export_operations fat_export_ops; 472extern const struct export_operations fat_export_ops_nostale; 473 474/* helper for printk */ 475typedef unsigned long long llu; 476 477#endif /* !_FAT_H */