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0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _FAT_H
0003 #define _FAT_H
0004 
0005 #include <linux/buffer_head.h>
0006 #include <linux/nls.h>
0007 #include <linux/hash.h>
0008 #include <linux/ratelimit.h>
0009 #include <linux/msdos_fs.h>
0010 
0011 /*
0012  * vfat shortname flags
0013  */
0014 #define VFAT_SFN_DISPLAY_LOWER  0x0001 /* convert to lowercase for display */
0015 #define VFAT_SFN_DISPLAY_WIN95  0x0002 /* emulate win95 rule for display */
0016 #define VFAT_SFN_DISPLAY_WINNT  0x0004 /* emulate winnt rule for display */
0017 #define VFAT_SFN_CREATE_WIN95   0x0100 /* emulate win95 rule for create */
0018 #define VFAT_SFN_CREATE_WINNT   0x0200 /* emulate winnt rule for create */
0019 
0020 #define FAT_ERRORS_CONT     1      /* ignore error and continue */
0021 #define FAT_ERRORS_PANIC    2      /* panic on error */
0022 #define FAT_ERRORS_RO       3      /* remount r/o on error */
0023 
0024 #define FAT_NFS_STALE_RW    1      /* NFS RW support, can cause ESTALE */
0025 #define FAT_NFS_NOSTALE_RO  2      /* NFS RO support, no ESTALE issue */
0026 
0027 struct fat_mount_options {
0028     kuid_t fs_uid;
0029     kgid_t fs_gid;
0030     unsigned short fs_fmask;
0031     unsigned short fs_dmask;
0032     unsigned short codepage;   /* Codepage for shortname conversions */
0033     int time_offset;       /* Offset of timestamps from UTC (in minutes) */
0034     char *iocharset;           /* Charset used for filename input/display */
0035     unsigned short shortname;  /* flags for shortname display/create rule */
0036     unsigned char name_check;  /* r = relaxed, n = normal, s = strict */
0037     unsigned char errors;      /* On error: continue, panic, remount-ro */
0038     unsigned char nfs;    /* NFS support: nostale_ro, stale_rw */
0039     unsigned short allow_utime;/* permission for setting the [am]time */
0040     unsigned quiet:1,          /* set = fake successful chmods and chowns */
0041          showexec:1,       /* set = only set x bit for com/exe/bat */
0042          sys_immutable:1,  /* set = system files are immutable */
0043          dotsOK:1,         /* set = hidden and system files are named '.filename' */
0044          isvfat:1,         /* 0=no vfat long filename support, 1=vfat support */
0045          utf8:1,       /* Use of UTF-8 character set (Default) */
0046          unicode_xlate:1,  /* create escape sequences for unhandled Unicode */
0047          numtail:1,        /* Does first alias have a numeric '~1' type tail? */
0048          flush:1,      /* write things quickly */
0049          nocase:1,     /* Does this need case conversion? 0=need case conversion*/
0050          usefree:1,    /* Use free_clusters for FAT32 */
0051          tz_set:1,     /* Filesystem timestamps' offset set */
0052          rodir:1,      /* allow ATTR_RO for directory */
0053          discard:1,    /* Issue discard requests on deletions */
0054          dos1xfloppy:1;    /* Assume default BPB for DOS 1.x floppies */
0055 };
0056 
0057 #define FAT_HASH_BITS   8
0058 #define FAT_HASH_SIZE   (1UL << FAT_HASH_BITS)
0059 
0060 /*
0061  * MS-DOS file system in-core superblock data
0062  */
0063 struct msdos_sb_info {
0064     unsigned short sec_per_clus;  /* sectors/cluster */
0065     unsigned short cluster_bits;  /* log2(cluster_size) */
0066     unsigned int cluster_size;    /* cluster size */
0067     unsigned char fats, fat_bits; /* number of FATs, FAT bits (12,16 or 32) */
0068     unsigned short fat_start;
0069     unsigned long fat_length;     /* FAT start & length (sec.) */
0070     unsigned long dir_start;
0071     unsigned short dir_entries;   /* root dir start & entries */
0072     unsigned long data_start;     /* first data sector */
0073     unsigned long max_cluster;    /* maximum cluster number */
0074     unsigned long root_cluster;   /* first cluster of the root directory */
0075     unsigned long fsinfo_sector;  /* sector number of FAT32 fsinfo */
0076     struct mutex fat_lock;
0077     struct mutex nfs_build_inode_lock;
0078     struct mutex s_lock;
0079     unsigned int prev_free;      /* previously allocated cluster number */
0080     unsigned int free_clusters;  /* -1 if undefined */
0081     unsigned int free_clus_valid; /* is free_clusters valid? */
0082     struct fat_mount_options options;
0083     struct nls_table *nls_disk;   /* Codepage used on disk */
0084     struct nls_table *nls_io;     /* Charset used for input and display */
0085     const void *dir_ops;          /* Opaque; default directory operations */
0086     int dir_per_block;        /* dir entries per block */
0087     int dir_per_block_bits;       /* log2(dir_per_block) */
0088     unsigned int vol_id;        /*volume ID*/
0089 
0090     int fatent_shift;
0091     const struct fatent_operations *fatent_ops;
0092     struct inode *fat_inode;
0093     struct inode *fsinfo_inode;
0094 
0095     struct ratelimit_state ratelimit;
0096 
0097     spinlock_t inode_hash_lock;
0098     struct hlist_head inode_hashtable[FAT_HASH_SIZE];
0099 
0100     spinlock_t dir_hash_lock;
0101     struct hlist_head dir_hashtable[FAT_HASH_SIZE];
0102 
0103     unsigned int dirty;           /* fs state before mount */
0104     struct rcu_head rcu;
0105 };
0106 
0107 #define FAT_CACHE_VALID 0   /* special case for valid cache */
0108 
0109 /*
0110  * MS-DOS file system inode data in memory
0111  */
0112 struct msdos_inode_info {
0113     spinlock_t cache_lru_lock;
0114     struct list_head cache_lru;
0115     int nr_caches;
0116     /* for avoiding the race between fat_free() and fat_get_cluster() */
0117     unsigned int cache_valid_id;
0118 
0119     /* NOTE: mmu_private is 64bits, so must hold ->i_mutex to access */
0120     loff_t mmu_private; /* physically allocated size */
0121 
0122     int i_start;        /* first cluster or 0 */
0123     int i_logstart;     /* logical first cluster */
0124     int i_attrs;        /* unused attribute bits */
0125     loff_t i_pos;       /* on-disk position of directory entry or 0 */
0126     struct hlist_node i_fat_hash;   /* hash by i_location */
0127     struct hlist_node i_dir_hash;   /* hash by i_logstart */
0128     struct rw_semaphore truncate_lock; /* protect bmap against truncate */
0129     struct timespec64 i_crtime; /* File creation (birth) time */
0130     struct inode vfs_inode;
0131 };
0132 
0133 struct fat_slot_info {
0134     loff_t i_pos;       /* on-disk position of directory entry */
0135     loff_t slot_off;    /* offset for slot or de start */
0136     int nr_slots;       /* number of slots + 1(de) in filename */
0137     struct msdos_dir_entry *de;
0138     struct buffer_head *bh;
0139 };
0140 
0141 static inline struct msdos_sb_info *MSDOS_SB(struct super_block *sb)
0142 {
0143     return sb->s_fs_info;
0144 }
0145 
0146 /*
0147  * Functions that determine the variant of the FAT file system (i.e.,
0148  * whether this is FAT12, FAT16 or FAT32.
0149  */
0150 static inline bool is_fat12(const struct msdos_sb_info *sbi)
0151 {
0152     return sbi->fat_bits == 12;
0153 }
0154 
0155 static inline bool is_fat16(const struct msdos_sb_info *sbi)
0156 {
0157     return sbi->fat_bits == 16;
0158 }
0159 
0160 static inline bool is_fat32(const struct msdos_sb_info *sbi)
0161 {
0162     return sbi->fat_bits == 32;
0163 }
0164 
0165 /* Maximum number of clusters */
0166 static inline u32 max_fat(struct super_block *sb)
0167 {
0168     struct msdos_sb_info *sbi = MSDOS_SB(sb);
0169 
0170     return is_fat32(sbi) ? MAX_FAT32 :
0171         is_fat16(sbi) ? MAX_FAT16 : MAX_FAT12;
0172 }
0173 
0174 static inline struct msdos_inode_info *MSDOS_I(struct inode *inode)
0175 {
0176     return container_of(inode, struct msdos_inode_info, vfs_inode);
0177 }
0178 
0179 /*
0180  * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to
0181  * save ATTR_RO instead of ->i_mode.
0182  *
0183  * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only
0184  * bit, it's just used as flag for app.
0185  */
0186 static inline int fat_mode_can_hold_ro(struct inode *inode)
0187 {
0188     struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
0189     umode_t mask;
0190 
0191     if (S_ISDIR(inode->i_mode)) {
0192         if (!sbi->options.rodir)
0193             return 0;
0194         mask = ~sbi->options.fs_dmask;
0195     } else
0196         mask = ~sbi->options.fs_fmask;
0197 
0198     if (!(mask & S_IWUGO))
0199         return 0;
0200     return 1;
0201 }
0202 
0203 /* Convert attribute bits and a mask to the UNIX mode. */
0204 static inline umode_t fat_make_mode(struct msdos_sb_info *sbi,
0205                    u8 attrs, umode_t mode)
0206 {
0207     if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir))
0208         mode &= ~S_IWUGO;
0209 
0210     if (attrs & ATTR_DIR)
0211         return (mode & ~sbi->options.fs_dmask) | S_IFDIR;
0212     else
0213         return (mode & ~sbi->options.fs_fmask) | S_IFREG;
0214 }
0215 
0216 /* Return the FAT attribute byte for this inode */
0217 static inline u8 fat_make_attrs(struct inode *inode)
0218 {
0219     u8 attrs = MSDOS_I(inode)->i_attrs;
0220     if (S_ISDIR(inode->i_mode))
0221         attrs |= ATTR_DIR;
0222     if (fat_mode_can_hold_ro(inode) && !(inode->i_mode & S_IWUGO))
0223         attrs |= ATTR_RO;
0224     return attrs;
0225 }
0226 
0227 static inline void fat_save_attrs(struct inode *inode, u8 attrs)
0228 {
0229     if (fat_mode_can_hold_ro(inode))
0230         MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED;
0231     else
0232         MSDOS_I(inode)->i_attrs = attrs & (ATTR_UNUSED | ATTR_RO);
0233 }
0234 
0235 static inline unsigned char fat_checksum(const __u8 *name)
0236 {
0237     unsigned char s = name[0];
0238     s = (s<<7) + (s>>1) + name[1];  s = (s<<7) + (s>>1) + name[2];
0239     s = (s<<7) + (s>>1) + name[3];  s = (s<<7) + (s>>1) + name[4];
0240     s = (s<<7) + (s>>1) + name[5];  s = (s<<7) + (s>>1) + name[6];
0241     s = (s<<7) + (s>>1) + name[7];  s = (s<<7) + (s>>1) + name[8];
0242     s = (s<<7) + (s>>1) + name[9];  s = (s<<7) + (s>>1) + name[10];
0243     return s;
0244 }
0245 
0246 static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus)
0247 {
0248     return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus
0249         + sbi->data_start;
0250 }
0251 
0252 static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi,
0253                 loff_t i_pos, sector_t *blknr, int *offset)
0254 {
0255     *blknr = i_pos >> sbi->dir_per_block_bits;
0256     *offset = i_pos & (sbi->dir_per_block - 1);
0257 }
0258 
0259 static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
0260                     struct inode *inode)
0261 {
0262     loff_t i_pos;
0263 #if BITS_PER_LONG == 32
0264     spin_lock(&sbi->inode_hash_lock);
0265 #endif
0266     i_pos = MSDOS_I(inode)->i_pos;
0267 #if BITS_PER_LONG == 32
0268     spin_unlock(&sbi->inode_hash_lock);
0269 #endif
0270     return i_pos;
0271 }
0272 
0273 static inline void fat16_towchar(wchar_t *dst, const __u8 *src, size_t len)
0274 {
0275 #ifdef __BIG_ENDIAN
0276     while (len--) {
0277         *dst++ = src[0] | (src[1] << 8);
0278         src += 2;
0279     }
0280 #else
0281     memcpy(dst, src, len * 2);
0282 #endif
0283 }
0284 
0285 static inline int fat_get_start(const struct msdos_sb_info *sbi,
0286                 const struct msdos_dir_entry *de)
0287 {
0288     int cluster = le16_to_cpu(de->start);
0289     if (is_fat32(sbi))
0290         cluster |= (le16_to_cpu(de->starthi) << 16);
0291     return cluster;
0292 }
0293 
0294 static inline void fat_set_start(struct msdos_dir_entry *de, int cluster)
0295 {
0296     de->start   = cpu_to_le16(cluster);
0297     de->starthi = cpu_to_le16(cluster >> 16);
0298 }
0299 
0300 static inline void fatwchar_to16(__u8 *dst, const wchar_t *src, size_t len)
0301 {
0302 #ifdef __BIG_ENDIAN
0303     while (len--) {
0304         dst[0] = *src & 0x00FF;
0305         dst[1] = (*src & 0xFF00) >> 8;
0306         dst += 2;
0307         src++;
0308     }
0309 #else
0310     memcpy(dst, src, len * 2);
0311 #endif
0312 }
0313 
0314 /* fat/cache.c */
0315 extern void fat_cache_inval_inode(struct inode *inode);
0316 extern int fat_get_cluster(struct inode *inode, int cluster,
0317                int *fclus, int *dclus);
0318 extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
0319                   sector_t last_block,
0320                   unsigned long *mapped_blocks, sector_t *bmap);
0321 extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
0322             unsigned long *mapped_blocks, int create, bool from_bmap);
0323 
0324 /* fat/dir.c */
0325 extern const struct file_operations fat_dir_operations;
0326 extern int fat_search_long(struct inode *inode, const unsigned char *name,
0327                int name_len, struct fat_slot_info *sinfo);
0328 extern int fat_dir_empty(struct inode *dir);
0329 extern int fat_subdirs(struct inode *dir);
0330 extern int fat_scan(struct inode *dir, const unsigned char *name,
0331             struct fat_slot_info *sinfo);
0332 extern int fat_scan_logstart(struct inode *dir, int i_logstart,
0333                  struct fat_slot_info *sinfo);
0334 extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
0335                 struct msdos_dir_entry **de);
0336 extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts);
0337 extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
0338                struct fat_slot_info *sinfo);
0339 extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo);
0340 
0341 /* fat/fatent.c */
0342 struct fat_entry {
0343     int entry;
0344     union {
0345         u8 *ent12_p[2];
0346         __le16 *ent16_p;
0347         __le32 *ent32_p;
0348     } u;
0349     int nr_bhs;
0350     struct buffer_head *bhs[2];
0351     struct inode *fat_inode;
0352 };
0353 
0354 static inline void fatent_init(struct fat_entry *fatent)
0355 {
0356     fatent->nr_bhs = 0;
0357     fatent->entry = 0;
0358     fatent->u.ent32_p = NULL;
0359     fatent->bhs[0] = fatent->bhs[1] = NULL;
0360     fatent->fat_inode = NULL;
0361 }
0362 
0363 static inline void fatent_set_entry(struct fat_entry *fatent, int entry)
0364 {
0365     fatent->entry = entry;
0366     fatent->u.ent32_p = NULL;
0367 }
0368 
0369 static inline void fatent_brelse(struct fat_entry *fatent)
0370 {
0371     int i;
0372     fatent->u.ent32_p = NULL;
0373     for (i = 0; i < fatent->nr_bhs; i++)
0374         brelse(fatent->bhs[i]);
0375     fatent->nr_bhs = 0;
0376     fatent->bhs[0] = fatent->bhs[1] = NULL;
0377     fatent->fat_inode = NULL;
0378 }
0379 
0380 static inline bool fat_valid_entry(struct msdos_sb_info *sbi, int entry)
0381 {
0382     return FAT_START_ENT <= entry && entry < sbi->max_cluster;
0383 }
0384 
0385 extern void fat_ent_access_init(struct super_block *sb);
0386 extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
0387             int entry);
0388 extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
0389              int new, int wait);
0390 extern int fat_alloc_clusters(struct inode *inode, int *cluster,
0391                   int nr_cluster);
0392 extern int fat_free_clusters(struct inode *inode, int cluster);
0393 extern int fat_count_free_clusters(struct super_block *sb);
0394 extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range);
0395 
0396 /* fat/file.c */
0397 extern long fat_generic_ioctl(struct file *filp, unsigned int cmd,
0398                   unsigned long arg);
0399 extern const struct file_operations fat_file_operations;
0400 extern const struct inode_operations fat_file_inode_operations;
0401 extern int fat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
0402                struct iattr *attr);
0403 extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
0404 extern int fat_getattr(struct user_namespace *mnt_userns,
0405                const struct path *path, struct kstat *stat,
0406                u32 request_mask, unsigned int flags);
0407 extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
0408               int datasync);
0409 
0410 /* fat/inode.c */
0411 extern int fat_block_truncate_page(struct inode *inode, loff_t from);
0412 extern void fat_attach(struct inode *inode, loff_t i_pos);
0413 extern void fat_detach(struct inode *inode);
0414 extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
0415 extern struct inode *fat_build_inode(struct super_block *sb,
0416             struct msdos_dir_entry *de, loff_t i_pos);
0417 extern int fat_sync_inode(struct inode *inode);
0418 extern int fat_fill_super(struct super_block *sb, void *data, int silent,
0419               int isvfat, void (*setup)(struct super_block *));
0420 extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
0421 
0422 extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
0423                 struct inode *i2);
0424 static inline unsigned long fat_dir_hash(int logstart)
0425 {
0426     return hash_32(logstart, FAT_HASH_BITS);
0427 }
0428 extern int fat_add_cluster(struct inode *inode);
0429 
0430 /* fat/misc.c */
0431 extern __printf(3, 4) __cold
0432 void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...);
0433 #define fat_fs_error(sb, fmt, args...)      \
0434     __fat_fs_error(sb, 1, fmt , ## args)
0435 #define fat_fs_error_ratelimit(sb, fmt, args...) \
0436     __fat_fs_error(sb, __ratelimit(&MSDOS_SB(sb)->ratelimit), fmt , ## args)
0437 
0438 #define FAT_PRINTK_PREFIX "%sFAT-fs (%s): "
0439 #define fat_msg(sb, level, fmt, args...)                \
0440 do {                                    \
0441     printk_index_subsys_emit(FAT_PRINTK_PREFIX, level, fmt, ##args);\
0442     _fat_msg(sb, level, fmt, ##args);               \
0443 } while (0)
0444 __printf(3, 4) __cold
0445 void _fat_msg(struct super_block *sb, const char *level, const char *fmt, ...);
0446 #define fat_msg_ratelimit(sb, level, fmt, args...)  \
0447     do {    \
0448             if (__ratelimit(&MSDOS_SB(sb)->ratelimit))  \
0449                 fat_msg(sb, level, fmt, ## args);   \
0450      } while (0)
0451 extern int fat_clusters_flush(struct super_block *sb);
0452 extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
0453 extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
0454                   __le16 __time, __le16 __date, u8 time_cs);
0455 extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
0456                   __le16 *time, __le16 *date, u8 *time_cs);
0457 extern struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
0458                         const struct timespec64 *ts);
0459 extern struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
0460                         const struct timespec64 *ts);
0461 extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
0462                  int flags);
0463 extern int fat_update_time(struct inode *inode, struct timespec64 *now,
0464                int flags);
0465 extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
0466 
0467 int fat_cache_init(void);
0468 void fat_cache_destroy(void);
0469 
0470 /* fat/nfs.c */
0471 extern const struct export_operations fat_export_ops;
0472 extern const struct export_operations fat_export_ops_nostale;
0473 
0474 /* helper for printk */
0475 typedef unsigned long long  llu;
0476 
0477 #endif /* !_FAT_H */
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