fs/fat/fat.h

   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
  27 struct 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  */
  63 struct 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  */
 112 struct 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
 133 struct 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
 141 static 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  */
 150 static inline bool is_fat12(const struct msdos_sb_info *sbi)
 151 {
 152         return sbi->fat_bits == 12;
 153 }
 154
 155 static inline bool is_fat16(const struct msdos_sb_info *sbi)
 156 {
 157         return sbi->fat_bits == 16;
 158 }
 159
 160 static inline bool is_fat32(const struct msdos_sb_info *sbi)
 161 {
 162         return sbi->fat_bits == 32;
 163 }
 164
 165 /* Maximum number of clusters */
 166 static 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
 174 static 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  */
 186 static 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. */
 204 static 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 */
 217 static 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
 227 static 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
 235 static 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
 246 static 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
 252 static 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
 259 static 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
 273 static 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
 285 static 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
 294 static 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
 300 static 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 */
 315 extern void fat_cache_inval_inode(struct inode *inode);
 316 extern int fat_get_cluster(struct inode *inode, int cluster,
 317                            int *fclus, int *dclus);
 318 extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
 319                                   sector_t last_block,
 320                                   unsigned long *mapped_blocks, sector_t *bmap);
 321 extern 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 */
 325 extern const struct file_operations fat_dir_operations;
 326 extern int fat_search_long(struct inode *inode, const unsigned char *name,
 327                            int name_len, struct fat_slot_info *sinfo);
 328 extern int fat_dir_empty(struct inode *dir);
 329 extern int fat_subdirs(struct inode *dir);
 330 extern int fat_scan(struct inode *dir, const unsigned char *name,
 331                     struct fat_slot_info *sinfo);
 332 extern int fat_scan_logstart(struct inode *dir, int i_logstart,
 333                              struct fat_slot_info *sinfo);
 334 extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
 335                                 struct msdos_dir_entry **de);
 336 extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts);
 337 extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
 338                            struct fat_slot_info *sinfo);
 339 extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo);
 340
 341 /* fat/fatent.c */
 342 struct 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
 354 static 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
 363 static inline void fatent_set_entry(struct fat_entry *fatent, int entry)
 364 {
 365         fatent->entry = entry;
 366         fatent->u.ent32_p = NULL;
 367 }
 368
 369 static 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
 380 static 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
 385 extern void fat_ent_access_init(struct super_block *sb);
 386 extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
 387                         int entry);
 388 extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
 389                          int new, int wait);
 390 extern int fat_alloc_clusters(struct inode *inode, int *cluster,
 391                               int nr_cluster);
 392 extern int fat_free_clusters(struct inode *inode, int cluster);
 393 extern int fat_count_free_clusters(struct super_block *sb);
 394 extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range);
 395
 396 /* fat/file.c */
 397 extern long fat_generic_ioctl(struct file *filp, unsigned int cmd,
 398                               unsigned long arg);
 399 extern const struct file_operations fat_file_operations;
 400 extern const struct inode_operations fat_file_inode_operations;
 401 extern int fat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 402                        struct iattr *attr);
 403 extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
 404 extern int fat_getattr(struct user_namespace *mnt_userns,
 405                        const struct path *path, struct kstat *stat,
 406                        u32 request_mask, unsigned int flags);
 407 extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
 408                           int datasync);
 409
 410 /* fat/inode.c */
 411 extern int fat_block_truncate_page(struct inode *inode, loff_t from);
 412 extern void fat_attach(struct inode *inode, loff_t i_pos);
 413 extern void fat_detach(struct inode *inode);
 414 extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
 415 extern struct inode *fat_build_inode(struct super_block *sb,
 416                         struct msdos_dir_entry *de, loff_t i_pos);
 417 extern int fat_sync_inode(struct inode *inode);
 418 extern int fat_fill_super(struct super_block *sb, void *data, int silent,
 419                           int isvfat, void (*setup)(struct super_block *));
 420 extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
 421
 422 extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
 423                             struct inode *i2);
 424 static inline unsigned long fat_dir_hash(int logstart)
 425 {
 426         return hash_32(logstart, FAT_HASH_BITS);
 427 }
 428 extern int fat_add_cluster(struct inode *inode);
 429
 430 /* fat/misc.c */
 431 extern __printf(3, 4) __cold
 432 void __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...)                                \
 440 do {                                                                    \
 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
 445 void _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)
 451 extern int fat_clusters_flush(struct super_block *sb);
 452 extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
 453 extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 454                               __le16 __time, __le16 __date, u8 time_cs);
 455 extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 456                               __le16 *time, __le16 *date, u8 *time_cs);
 457 extern struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
 458                                             const struct timespec64 *ts);
 459 extern struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
 460                                             const struct timespec64 *ts);
 461 extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
 462                              int flags);
 463 extern int fat_update_time(struct inode *inode, struct timespec64 *now,
 464                            int flags);
 465 extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
 466
 467 int fat_cache_init(void);
 468 void fat_cache_destroy(void);
 469
 470 /* fat/nfs.c */
 471 extern const struct export_operations fat_export_ops;
 472 extern const struct export_operations fat_export_ops_nostale;
 473
 474 /* helper for printk */
 475 typedef unsigned long long      llu;
 476
 477 #endif /* !_FAT_H */