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TOMOYO Linux Cross Reference
Linux/fs/fat/fat.h

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  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 dentry *dentry, struct iattr *attr);
401 extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
402 extern int fat_getattr(const struct path *path, struct kstat *stat,
403                        u32 request_mask, unsigned int flags);
404 extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
405                           int datasync);
406 
407 /* fat/inode.c */
408 extern int fat_block_truncate_page(struct inode *inode, loff_t from);
409 extern void fat_attach(struct inode *inode, loff_t i_pos);
410 extern void fat_detach(struct inode *inode);
411 extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
412 extern struct inode *fat_build_inode(struct super_block *sb,
413                         struct msdos_dir_entry *de, loff_t i_pos);
414 extern int fat_sync_inode(struct inode *inode);
415 extern int fat_fill_super(struct super_block *sb, void *data, int silent,
416                           int isvfat, void (*setup)(struct super_block *));
417 extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
418 
419 extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
420                             struct inode *i2);
421 static inline unsigned long fat_dir_hash(int logstart)
422 {
423         return hash_32(logstart, FAT_HASH_BITS);
424 }
425 extern int fat_add_cluster(struct inode *inode);
426 
427 /* fat/misc.c */
428 extern __printf(3, 4) __cold
429 void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...);
430 #define fat_fs_error(sb, fmt, args...)          \
431         __fat_fs_error(sb, 1, fmt , ## args)
432 #define fat_fs_error_ratelimit(sb, fmt, args...) \
433         __fat_fs_error(sb, __ratelimit(&MSDOS_SB(sb)->ratelimit), fmt , ## args)
434 __printf(3, 4) __cold
435 void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...);
436 #define fat_msg_ratelimit(sb, level, fmt, args...)      \
437         do {    \
438                         if (__ratelimit(&MSDOS_SB(sb)->ratelimit))      \
439                                 fat_msg(sb, level, fmt, ## args);       \
440          } while (0)
441 extern int fat_clusters_flush(struct super_block *sb);
442 extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
443 extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
444                               __le16 __time, __le16 __date, u8 time_cs);
445 extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
446                               __le16 *time, __le16 *date, u8 *time_cs);
447 extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
448                              int flags);
449 extern int fat_update_time(struct inode *inode, struct timespec64 *now,
450                            int flags);
451 extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
452 
453 int fat_cache_init(void);
454 void fat_cache_destroy(void);
455 
456 /* fat/nfs.c */
457 extern const struct export_operations fat_export_ops;
458 extern const struct export_operations fat_export_ops_nostale;
459 
460 /* helper for printk */
461 typedef unsigned long long      llu;
462 
463 #endif /* !_FAT_H */
464 

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