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 inode vfs_inode;
 130 };
 131
 132 struct fat_slot_info {
 133         loff_t i_pos;           /* on-disk position of directory entry */
 134         loff_t slot_off;        /* offset for slot or de start */
 135         int nr_slots;           /* number of slots + 1(de) in filename */
 136         struct msdos_dir_entry *de;
 137         struct buffer_head *bh;
 138 };
 139
 140 static inline struct msdos_sb_info *MSDOS_SB(struct super_block *sb)
 141 {
 142         return sb->s_fs_info;
 143 }
 144
 145 /*
 146  * Functions that determine the variant of the FAT file system (i.e.,
 147  * whether this is FAT12, FAT16 or FAT32.
 148  */
 149 static inline bool is_fat12(const struct msdos_sb_info *sbi)
 150 {
 151         return sbi->fat_bits == 12;
 152 }
 153
 154 static inline bool is_fat16(const struct msdos_sb_info *sbi)
 155 {
 156         return sbi->fat_bits == 16;
 157 }
 158
 159 static inline bool is_fat32(const struct msdos_sb_info *sbi)
 160 {
 161         return sbi->fat_bits == 32;
 162 }
 163
 164 /* Maximum number of clusters */
 165 static inline u32 max_fat(struct super_block *sb)
 166 {
 167         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 168
 169         return is_fat32(sbi) ? MAX_FAT32 :
 170                 is_fat16(sbi) ? MAX_FAT16 : MAX_FAT12;
 171 }
 172
 173 static inline struct msdos_inode_info *MSDOS_I(struct inode *inode)
 174 {
 175         return container_of(inode, struct msdos_inode_info, vfs_inode);
 176 }
 177
 178 /*
 179  * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to
 180  * save ATTR_RO instead of ->i_mode.
 181  *
 182  * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only
 183  * bit, it's just used as flag for app.
 184  */
 185 static inline int fat_mode_can_hold_ro(struct inode *inode)
 186 {
 187         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 188         umode_t mask;
 189
 190         if (S_ISDIR(inode->i_mode)) {
 191                 if (!sbi->options.rodir)
 192                         return 0;
 193                 mask = ~sbi->options.fs_dmask;
 194         } else
 195                 mask = ~sbi->options.fs_fmask;
 196
 197         if (!(mask & S_IWUGO))
 198                 return 0;
 199         return 1;
 200 }
 201
 202 /* Convert attribute bits and a mask to the UNIX mode. */
 203 static inline umode_t fat_make_mode(struct msdos_sb_info *sbi,
 204                                    u8 attrs, umode_t mode)
 205 {
 206         if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir))
 207                 mode &= ~S_IWUGO;
 208
 209         if (attrs & ATTR_DIR)
 210                 return (mode & ~sbi->options.fs_dmask) | S_IFDIR;
 211         else
 212                 return (mode & ~sbi->options.fs_fmask) | S_IFREG;
 213 }
 214
 215 /* Return the FAT attribute byte for this inode */
 216 static inline u8 fat_make_attrs(struct inode *inode)
 217 {
 218         u8 attrs = MSDOS_I(inode)->i_attrs;
 219         if (S_ISDIR(inode->i_mode))
 220                 attrs |= ATTR_DIR;
 221         if (fat_mode_can_hold_ro(inode) && !(inode->i_mode & S_IWUGO))
 222                 attrs |= ATTR_RO;
 223         return attrs;
 224 }
 225
 226 static inline void fat_save_attrs(struct inode *inode, u8 attrs)
 227 {
 228         if (fat_mode_can_hold_ro(inode))
 229                 MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED;
 230         else
 231                 MSDOS_I(inode)->i_attrs = attrs & (ATTR_UNUSED | ATTR_RO);
 232 }
 233
 234 static inline unsigned char fat_checksum(const __u8 *name)
 235 {
 236         unsigned char s = name[0];
 237         s = (s<<7) + (s>>1) + name[1];  s = (s<<7) + (s>>1) + name[2];
 238         s = (s<<7) + (s>>1) + name[3];  s = (s<<7) + (s>>1) + name[4];
 239         s = (s<<7) + (s>>1) + name[5];  s = (s<<7) + (s>>1) + name[6];
 240         s = (s<<7) + (s>>1) + name[7];  s = (s<<7) + (s>>1) + name[8];
 241         s = (s<<7) + (s>>1) + name[9];  s = (s<<7) + (s>>1) + name[10];
 242         return s;
 243 }
 244
 245 static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus)
 246 {
 247         return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus
 248                 + sbi->data_start;
 249 }
 250
 251 static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi,
 252                                 loff_t i_pos, sector_t *blknr, int *offset)
 253 {
 254         *blknr = i_pos >> sbi->dir_per_block_bits;
 255         *offset = i_pos & (sbi->dir_per_block - 1);
 256 }
 257
 258 static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
 259                                         struct inode *inode)
 260 {
 261         loff_t i_pos;
 262 #if BITS_PER_LONG == 32
 263         spin_lock(&sbi->inode_hash_lock);
 264 #endif
 265         i_pos = MSDOS_I(inode)->i_pos;
 266 #if BITS_PER_LONG == 32
 267         spin_unlock(&sbi->inode_hash_lock);
 268 #endif
 269         return i_pos;
 270 }
 271
 272 static inline void fat16_towchar(wchar_t *dst, const __u8 *src, size_t len)
 273 {
 274 #ifdef __BIG_ENDIAN
 275         while (len--) {
 276                 *dst++ = src[0] | (src[1] << 8);
 277                 src += 2;
 278         }
 279 #else
 280         memcpy(dst, src, len * 2);
 281 #endif
 282 }
 283
 284 static inline int fat_get_start(const struct msdos_sb_info *sbi,
 285                                 const struct msdos_dir_entry *de)
 286 {
 287         int cluster = le16_to_cpu(de->start);
 288         if (is_fat32(sbi))
 289                 cluster |= (le16_to_cpu(de->starthi) << 16);
 290         return cluster;
 291 }
 292
 293 static inline void fat_set_start(struct msdos_dir_entry *de, int cluster)
 294 {
 295         de->start   = cpu_to_le16(cluster);
 296         de->starthi = cpu_to_le16(cluster >> 16);
 297 }
 298
 299 static inline void fatwchar_to16(__u8 *dst, const wchar_t *src, size_t len)
 300 {
 301 #ifdef __BIG_ENDIAN
 302         while (len--) {
 303                 dst[0] = *src & 0x00FF;
 304                 dst[1] = (*src & 0xFF00) >> 8;
 305                 dst += 2;
 306                 src++;
 307         }
 308 #else
 309         memcpy(dst, src, len * 2);
 310 #endif
 311 }
 312
 313 /* fat/cache.c */
 314 extern void fat_cache_inval_inode(struct inode *inode);
 315 extern int fat_get_cluster(struct inode *inode, int cluster,
 316                            int *fclus, int *dclus);
 317 extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
 318                                   sector_t last_block,
 319                                   unsigned long *mapped_blocks, sector_t *bmap);
 320 extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
 321                     unsigned long *mapped_blocks, int create, bool from_bmap);
 322
 323 /* fat/dir.c */
 324 extern const struct file_operations fat_dir_operations;
 325 extern int fat_search_long(struct inode *inode, const unsigned char *name,
 326                            int name_len, struct fat_slot_info *sinfo);
 327 extern int fat_dir_empty(struct inode *dir);
 328 extern int fat_subdirs(struct inode *dir);
 329 extern int fat_scan(struct inode *dir, const unsigned char *name,
 330                     struct fat_slot_info *sinfo);
 331 extern int fat_scan_logstart(struct inode *dir, int i_logstart,
 332                              struct fat_slot_info *sinfo);
 333 extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
 334                                 struct msdos_dir_entry **de);
 335 extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts);
 336 extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
 337                            struct fat_slot_info *sinfo);
 338 extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo);
 339
 340 /* fat/fatent.c */
 341 struct fat_entry {
 342         int entry;
 343         union {
 344                 u8 *ent12_p[2];
 345                 __le16 *ent16_p;
 346                 __le32 *ent32_p;
 347         } u;
 348         int nr_bhs;
 349         struct buffer_head *bhs[2];
 350         struct inode *fat_inode;
 351 };
 352
 353 static inline void fatent_init(struct fat_entry *fatent)
 354 {
 355         fatent->nr_bhs = 0;
 356         fatent->entry = 0;
 357         fatent->u.ent32_p = NULL;
 358         fatent->bhs[0] = fatent->bhs[1] = NULL;
 359         fatent->fat_inode = NULL;
 360 }
 361
 362 static inline void fatent_set_entry(struct fat_entry *fatent, int entry)
 363 {
 364         fatent->entry = entry;
 365         fatent->u.ent32_p = NULL;
 366 }
 367
 368 static inline void fatent_brelse(struct fat_entry *fatent)
 369 {
 370         int i;
 371         fatent->u.ent32_p = NULL;
 372         for (i = 0; i < fatent->nr_bhs; i++)
 373                 brelse(fatent->bhs[i]);
 374         fatent->nr_bhs = 0;
 375         fatent->bhs[0] = fatent->bhs[1] = NULL;
 376         fatent->fat_inode = NULL;
 377 }
 378
 379 static inline bool fat_valid_entry(struct msdos_sb_info *sbi, int entry)
 380 {
 381         return FAT_START_ENT <= entry && entry < sbi->max_cluster;
 382 }
 383
 384 extern void fat_ent_access_init(struct super_block *sb);
 385 extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
 386                         int entry);
 387 extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
 388                          int new, int wait);
 389 extern int fat_alloc_clusters(struct inode *inode, int *cluster,
 390                               int nr_cluster);
 391 extern int fat_free_clusters(struct inode *inode, int cluster);
 392 extern int fat_count_free_clusters(struct super_block *sb);
 393 extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range);
 394
 395 /* fat/file.c */
 396 extern long fat_generic_ioctl(struct file *filp, unsigned int cmd,
 397                               unsigned long arg);
 398 extern const struct file_operations fat_file_operations;
 399 extern const struct inode_operations fat_file_inode_operations;
 400 extern int fat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 401                        struct iattr *attr);
 402 extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
 403 extern int fat_getattr(struct user_namespace *mnt_userns,
 404                        const struct path *path, struct kstat *stat,
 405                        u32 request_mask, unsigned int flags);
 406 extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
 407                           int datasync);
 408
 409 /* fat/inode.c */
 410 extern int fat_block_truncate_page(struct inode *inode, loff_t from);
 411 extern void fat_attach(struct inode *inode, loff_t i_pos);
 412 extern void fat_detach(struct inode *inode);
 413 extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
 414 extern struct inode *fat_build_inode(struct super_block *sb,
 415                         struct msdos_dir_entry *de, loff_t i_pos);
 416 extern int fat_sync_inode(struct inode *inode);
 417 extern int fat_fill_super(struct super_block *sb, void *data, int silent,
 418                           int isvfat, void (*setup)(struct super_block *));
 419 extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
 420
 421 extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
 422                             struct inode *i2);
 423 static inline unsigned long fat_dir_hash(int logstart)
 424 {
 425         return hash_32(logstart, FAT_HASH_BITS);
 426 }
 427 extern int fat_add_cluster(struct inode *inode);
 428
 429 /* fat/misc.c */
 430 extern __printf(3, 4) __cold
 431 void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...);
 432 #define fat_fs_error(sb, fmt, args...)          \
 433         __fat_fs_error(sb, 1, fmt , ## args)
 434 #define fat_fs_error_ratelimit(sb, fmt, args...) \
 435         __fat_fs_error(sb, __ratelimit(&MSDOS_SB(sb)->ratelimit), fmt , ## args)
 436 __printf(3, 4) __cold
 437 void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...);
 438 #define fat_msg_ratelimit(sb, level, fmt, args...)      \
 439         do {    \
 440                         if (__ratelimit(&MSDOS_SB(sb)->ratelimit))      \
 441                                 fat_msg(sb, level, fmt, ## args);       \
 442          } while (0)
 443 extern int fat_clusters_flush(struct super_block *sb);
 444 extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
 445 extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 446                               __le16 __time, __le16 __date, u8 time_cs);
 447 extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 448                               __le16 *time, __le16 *date, u8 *time_cs);
 449 extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
 450                              int flags);
 451 extern int fat_update_time(struct inode *inode, struct timespec64 *now,
 452                            int flags);
 453 extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
 454
 455 int fat_cache_init(void);
 456 void fat_cache_destroy(void);
 457
 458 /* fat/nfs.c */
 459 extern const struct export_operations fat_export_ops;
 460 extern const struct export_operations fat_export_ops_nostale;
 461
 462 /* helper for printk */
 463 typedef unsigned long long      llu;
 464
 465 #endif /* !_FAT_H */