LXR linux/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
  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 inode vfs_inode;
 130};
 131
 132struct 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
 140static 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 */
 149static inline bool is_fat12(const struct msdos_sb_info *sbi)
 150{
 151        return sbi->fat_bits == 12;
 152}
 153
 154static inline bool is_fat16(const struct msdos_sb_info *sbi)
 155{
 156        return sbi->fat_bits == 16;
 157}
 158
 159static inline bool is_fat32(const struct msdos_sb_info *sbi)
 160{
 161        return sbi->fat_bits == 32;
 162}
 163
 164/* Maximum number of clusters */
 165static 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
 173static 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 */
 185static 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. */
 203static 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 */
 216static 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
 226static 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
 234static 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
 245static 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
 251static 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
 258static 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
 272static 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
 284static 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
 293static 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
 299static 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 */
 314extern void fat_cache_inval_inode(struct inode *inode);
 315extern int fat_get_cluster(struct inode *inode, int cluster,
 316                           int *fclus, int *dclus);
 317extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
 318                                  sector_t last_block,
 319                                  unsigned long *mapped_blocks, sector_t *bmap);
 320extern 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 */
 324extern const struct file_operations fat_dir_operations;
 325extern int fat_search_long(struct inode *inode, const unsigned char *name,
 326                           int name_len, struct fat_slot_info *sinfo);
 327extern int fat_dir_empty(struct inode *dir);
 328extern int fat_subdirs(struct inode *dir);
 329extern int fat_scan(struct inode *dir, const unsigned char *name,
 330                    struct fat_slot_info *sinfo);
 331extern int fat_scan_logstart(struct inode *dir, int i_logstart,
 332                             struct fat_slot_info *sinfo);
 333extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
 334                                struct msdos_dir_entry **de);
 335extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts);
 336extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
 337                           struct fat_slot_info *sinfo);
 338extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo);
 339
 340/* fat/fatent.c */
 341struct 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
 353static 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
 362static inline void fatent_set_entry(struct fat_entry *fatent, int entry)
 363{
 364        fatent->entry = entry;
 365        fatent->u.ent32_p = NULL;
 366}
 367
 368static 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
 379static 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
 384extern void fat_ent_access_init(struct super_block *sb);
 385extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
 386                        int entry);
 387extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
 388                         int new, int wait);
 389extern int fat_alloc_clusters(struct inode *inode, int *cluster,
 390                              int nr_cluster);
 391extern int fat_free_clusters(struct inode *inode, int cluster);
 392extern int fat_count_free_clusters(struct super_block *sb);
 393extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range);
 394
 395/* fat/file.c */
 396extern long fat_generic_ioctl(struct file *filp, unsigned int cmd,
 397                              unsigned long arg);
 398extern const struct file_operations fat_file_operations;
 399extern const struct inode_operations fat_file_inode_operations;
 400extern int fat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 401                       struct iattr *attr);
 402extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
 403extern int fat_getattr(struct user_namespace *mnt_userns,
 404                       const struct path *path, struct kstat *stat,
 405                       u32 request_mask, unsigned int flags);
 406extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
 407                          int datasync);
 408
 409/* fat/inode.c */
 410extern int fat_block_truncate_page(struct inode *inode, loff_t from);
 411extern void fat_attach(struct inode *inode, loff_t i_pos);
 412extern void fat_detach(struct inode *inode);
 413extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
 414extern struct inode *fat_build_inode(struct super_block *sb,
 415                        struct msdos_dir_entry *de, loff_t i_pos);
 416extern int fat_sync_inode(struct inode *inode);
 417extern int fat_fill_super(struct super_block *sb, void *data, int silent,
 418                          int isvfat, void (*setup)(struct super_block *));
 419extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
 420
 421extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
 422                            struct inode *i2);
 423static inline unsigned long fat_dir_hash(int logstart)
 424{
 425        return hash_32(logstart, FAT_HASH_BITS);
 426}
 427extern int fat_add_cluster(struct inode *inode);
 428
 429/* fat/misc.c */
 430extern __printf(3, 4) __cold
 431void __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
 437void 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)
 443extern int fat_clusters_flush(struct super_block *sb);
 444extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
 445extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 446                              __le16 __time, __le16 __date, u8 time_cs);
 447extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 448                              __le16 *time, __le16 *date, u8 *time_cs);
 449extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
 450                             int flags);
 451extern int fat_update_time(struct inode *inode, struct timespec64 *now,
 452                           int flags);
 453extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
 454
 455int fat_cache_init(void);
 456void fat_cache_destroy(void);
 457
 458/* fat/nfs.c */
 459extern const struct export_operations fat_export_ops;
 460extern const struct export_operations fat_export_ops_nostale;
 461
 462/* helper for printk */
 463typedef unsigned long long      llu;
 464
 465#endif /* !_FAT_H */
 466