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#include <linux/fs_context.h>
11#include <linux/fs_parser.h>
12
13/*
14 * vfat shortname flags
15 */
16#define VFAT_SFN_DISPLAY_LOWER 0x0001 /* convert to lowercase for display */
17#define VFAT_SFN_DISPLAY_WIN95 0x0002 /* emulate win95 rule for display */
18#define VFAT_SFN_DISPLAY_WINNT 0x0004 /* emulate winnt rule for display */
19#define VFAT_SFN_CREATE_WIN95 0x0100 /* emulate win95 rule for create */
20#define VFAT_SFN_CREATE_WINNT 0x0200 /* emulate winnt rule for create */
21
22#define FAT_ERRORS_CONT 1 /* ignore error and continue */
23#define FAT_ERRORS_PANIC 2 /* panic on error */
24#define FAT_ERRORS_RO 3 /* remount r/o on error */
25
26#define FAT_NFS_STALE_RW 1 /* NFS RW support, can cause ESTALE */
27#define FAT_NFS_NOSTALE_RO 2 /* NFS RO support, no ESTALE issue */
28
29struct fat_mount_options {
30 kuid_t fs_uid;
31 kgid_t fs_gid;
32 unsigned short fs_fmask;
33 unsigned short fs_dmask;
34 unsigned short codepage; /* Codepage for shortname conversions */
35 int time_offset; /* Offset of timestamps from UTC (in minutes) */
36 char *iocharset; /* Charset used for filename input/display */
37 unsigned short shortname; /* flags for shortname display/create rule */
38 unsigned char name_check; /* r = relaxed, n = normal, s = strict */
39 unsigned char errors; /* On error: continue, panic, remount-ro */
40 unsigned char nfs; /* NFS support: nostale_ro, stale_rw */
41 unsigned short allow_utime;/* permission for setting the [am]time */
42 unsigned quiet:1, /* set = fake successful chmods and chowns */
43 showexec:1, /* set = only set x bit for com/exe/bat */
44 sys_immutable:1, /* set = system files are immutable */
45 dotsOK:1, /* set = hidden and system files are named '.filename' */
46 isvfat:1, /* 0=no vfat long filename support, 1=vfat support */
47 utf8:1, /* Use of UTF-8 character set (Default) */
48 unicode_xlate:1, /* create escape sequences for unhandled Unicode */
49 numtail:1, /* Does first alias have a numeric '~1' type tail? */
50 flush:1, /* write things quickly */
51 nocase:1, /* Does this need case conversion? 0=need case conversion*/
52 usefree:1, /* Use free_clusters for FAT32 */
53 tz_set:1, /* Filesystem timestamps' offset set */
54 rodir:1, /* allow ATTR_RO for directory */
55 discard:1, /* Issue discard requests on deletions */
56 dos1xfloppy:1, /* Assume default BPB for DOS 1.x floppies */
57 debug:1; /* Not currently used */
58};
59
60#define FAT_HASH_BITS 8
61#define FAT_HASH_SIZE (1UL << FAT_HASH_BITS)
62
63/*
64 * MS-DOS file system in-core superblock data
65 */
66struct msdos_sb_info {
67 unsigned short sec_per_clus; /* sectors/cluster */
68 unsigned short cluster_bits; /* log2(cluster_size) */
69 unsigned int cluster_size; /* cluster size */
70 unsigned char fats, fat_bits; /* number of FATs, FAT bits (12,16 or 32) */
71 unsigned short fat_start;
72 unsigned long fat_length; /* FAT start & length (sec.) */
73 unsigned long dir_start;
74 unsigned short dir_entries; /* root dir start & entries */
75 unsigned long data_start; /* first data sector */
76 unsigned long max_cluster; /* maximum cluster number */
77 unsigned long root_cluster; /* first cluster of the root directory */
78 unsigned long fsinfo_sector; /* sector number of FAT32 fsinfo */
79 struct mutex fat_lock;
80 struct mutex nfs_build_inode_lock;
81 struct mutex s_lock;
82 unsigned int prev_free; /* previously allocated cluster number */
83 unsigned int free_clusters; /* -1 if undefined */
84 unsigned int free_clus_valid; /* is free_clusters valid? */
85 struct fat_mount_options options;
86 struct nls_table *nls_disk; /* Codepage used on disk */
87 struct nls_table *nls_io; /* Charset used for input and display */
88 const void *dir_ops; /* Opaque; default directory operations */
89 int dir_per_block; /* dir entries per block */
90 int dir_per_block_bits; /* log2(dir_per_block) */
91 unsigned int vol_id; /*volume ID*/
92
93 int fatent_shift;
94 const struct fatent_operations *fatent_ops;
95 struct inode *fat_inode;
96 struct inode *fsinfo_inode;
97
98 struct ratelimit_state ratelimit;
99
100 spinlock_t inode_hash_lock;
101 struct hlist_head inode_hashtable[FAT_HASH_SIZE];
102
103 spinlock_t dir_hash_lock;
104 struct hlist_head dir_hashtable[FAT_HASH_SIZE];
105
106 unsigned int dirty; /* fs state before mount */
107 struct rcu_head rcu;
108};
109
110#define FAT_CACHE_VALID 0 /* special case for valid cache */
111
112/*
113 * MS-DOS file system inode data in memory
114 */
115struct msdos_inode_info {
116 spinlock_t cache_lru_lock;
117 struct list_head cache_lru;
118 int nr_caches;
119 /* for avoiding the race between fat_free() and fat_get_cluster() */
120 unsigned int cache_valid_id;
121
122 /* NOTE: mmu_private is 64bits, so must hold ->i_mutex to access */
123 loff_t mmu_private; /* physically allocated size */
124
125 int i_start; /* first cluster or 0 */
126 int i_logstart; /* logical first cluster */
127 int i_attrs; /* unused attribute bits */
128 loff_t i_pos; /* on-disk position of directory entry or 0 */
129 struct hlist_node i_fat_hash; /* hash by i_location */
130 struct hlist_node i_dir_hash; /* hash by i_logstart */
131 struct rw_semaphore truncate_lock; /* protect bmap against truncate */
132 struct timespec64 i_crtime; /* File creation (birth) time */
133 struct inode vfs_inode;
134};
135
136struct fat_slot_info {
137 loff_t i_pos; /* on-disk position of directory entry */
138 loff_t slot_off; /* offset for slot or de start */
139 int nr_slots; /* number of slots + 1(de) in filename */
140 struct msdos_dir_entry *de;
141 struct buffer_head *bh;
142};
143
144static inline struct msdos_sb_info *MSDOS_SB(struct super_block *sb)
145{
146 return sb->s_fs_info;
147}
148
149/*
150 * Functions that determine the variant of the FAT file system (i.e.,
151 * whether this is FAT12, FAT16 or FAT32.
152 */
153static inline bool is_fat12(const struct msdos_sb_info *sbi)
154{
155 return sbi->fat_bits == 12;
156}
157
158static inline bool is_fat16(const struct msdos_sb_info *sbi)
159{
160 return sbi->fat_bits == 16;
161}
162
163static inline bool is_fat32(const struct msdos_sb_info *sbi)
164{
165 return sbi->fat_bits == 32;
166}
167
168/* Maximum number of clusters */
169static inline u32 max_fat(struct super_block *sb)
170{
171 struct msdos_sb_info *sbi = MSDOS_SB(sb);
172
173 return is_fat32(sbi) ? MAX_FAT32 :
174 is_fat16(sbi) ? MAX_FAT16 : MAX_FAT12;
175}
176
177static inline struct msdos_inode_info *MSDOS_I(struct inode *inode)
178{
179 return container_of(inode, struct msdos_inode_info, vfs_inode);
180}
181
182/*
183 * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to
184 * save ATTR_RO instead of ->i_mode.
185 *
186 * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only
187 * bit, it's just used as flag for app.
188 */
189static inline int fat_mode_can_hold_ro(struct inode *inode)
190{
191 struct msdos_sb_info *sbi = MSDOS_SB(sb: inode->i_sb);
192 umode_t mask;
193
194 if (S_ISDIR(inode->i_mode)) {
195 if (!sbi->options.rodir)
196 return 0;
197 mask = ~sbi->options.fs_dmask;
198 } else
199 mask = ~sbi->options.fs_fmask;
200
201 if (!(mask & S_IWUGO))
202 return 0;
203 return 1;
204}
205
206/* Convert attribute bits and a mask to the UNIX mode. */
207static inline umode_t fat_make_mode(struct msdos_sb_info *sbi,
208 u8 attrs, umode_t mode)
209{
210 if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir))
211 mode &= ~S_IWUGO;
212
213 if (attrs & ATTR_DIR)
214 return (mode & ~sbi->options.fs_dmask) | S_IFDIR;
215 else
216 return (mode & ~sbi->options.fs_fmask) | S_IFREG;
217}
218
219/* Return the FAT attribute byte for this inode */
220static inline u8 fat_make_attrs(struct inode *inode)
221{
222 u8 attrs = MSDOS_I(inode)->i_attrs;
223 if (S_ISDIR(inode->i_mode))
224 attrs |= ATTR_DIR;
225 if (fat_mode_can_hold_ro(inode) && !(inode->i_mode & S_IWUGO))
226 attrs |= ATTR_RO;
227 return attrs;
228}
229
230static inline void fat_save_attrs(struct inode *inode, u8 attrs)
231{
232 if (fat_mode_can_hold_ro(inode))
233 MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED;
234 else
235 MSDOS_I(inode)->i_attrs = attrs & (ATTR_UNUSED | ATTR_RO);
236}
237
238static inline unsigned char fat_checksum(const __u8 *name)
239{
240 unsigned char s = name[0];
241 s = (s<<7) + (s>>1) + name[1]; s = (s<<7) + (s>>1) + name[2];
242 s = (s<<7) + (s>>1) + name[3]; s = (s<<7) + (s>>1) + name[4];
243 s = (s<<7) + (s>>1) + name[5]; s = (s<<7) + (s>>1) + name[6];
244 s = (s<<7) + (s>>1) + name[7]; s = (s<<7) + (s>>1) + name[8];
245 s = (s<<7) + (s>>1) + name[9]; s = (s<<7) + (s>>1) + name[10];
246 return s;
247}
248
249static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus)
250{
251 return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus
252 + sbi->data_start;
253}
254
255static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi,
256 loff_t i_pos, sector_t *blknr, int *offset)
257{
258 *blknr = i_pos >> sbi->dir_per_block_bits;
259 *offset = i_pos & (sbi->dir_per_block - 1);
260}
261
262static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
263 struct inode *inode)
264{
265 loff_t i_pos;
266#if BITS_PER_LONG == 32
267 spin_lock(&sbi->inode_hash_lock);
268#endif
269 i_pos = MSDOS_I(inode)->i_pos;
270#if BITS_PER_LONG == 32
271 spin_unlock(&sbi->inode_hash_lock);
272#endif
273 return i_pos;
274}
275
276static inline void fat16_towchar(wchar_t *dst, const __u8 *src, size_t len)
277{
278#ifdef __BIG_ENDIAN
279 while (len--) {
280 *dst++ = src[0] | (src[1] << 8);
281 src += 2;
282 }
283#else
284 memcpy(dst, src, len * 2);
285#endif
286}
287
288static inline int fat_get_start(const struct msdos_sb_info *sbi,
289 const struct msdos_dir_entry *de)
290{
291 int cluster = le16_to_cpu(de->start);
292 if (is_fat32(sbi))
293 cluster |= (le16_to_cpu(de->starthi) << 16);
294 return cluster;
295}
296
297static inline void fat_set_start(struct msdos_dir_entry *de, int cluster)
298{
299 de->start = cpu_to_le16(cluster);
300 de->starthi = cpu_to_le16(cluster >> 16);
301}
302
303static inline void fatwchar_to16(__u8 *dst, const wchar_t *src, size_t len)
304{
305#ifdef __BIG_ENDIAN
306 while (len--) {
307 dst[0] = *src & 0x00FF;
308 dst[1] = (*src & 0xFF00) >> 8;
309 dst += 2;
310 src++;
311 }
312#else
313 memcpy(dst, src, len * 2);
314#endif
315}
316
317/* fat/cache.c */
318extern void fat_cache_inval_inode(struct inode *inode);
319extern int fat_get_cluster(struct inode *inode, int cluster,
320 int *fclus, int *dclus);
321extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
322 sector_t last_block,
323 unsigned long *mapped_blocks, sector_t *bmap);
324extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
325 unsigned long *mapped_blocks, int create, bool from_bmap);
326
327/* fat/dir.c */
328extern const struct file_operations fat_dir_operations;
329extern int fat_search_long(struct inode *inode, const unsigned char *name,
330 int name_len, struct fat_slot_info *sinfo);
331extern int fat_dir_empty(struct inode *dir);
332extern int fat_subdirs(struct inode *dir);
333extern int fat_scan(struct inode *dir, const unsigned char *name,
334 struct fat_slot_info *sinfo);
335extern int fat_scan_logstart(struct inode *dir, int i_logstart,
336 struct fat_slot_info *sinfo);
337extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
338 struct msdos_dir_entry **de);
339extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts);
340extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
341 struct fat_slot_info *sinfo);
342extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo);
343
344/* fat/fatent.c */
345struct fat_entry {
346 int entry;
347 union {
348 u8 *ent12_p[2];
349 __le16 *ent16_p;
350 __le32 *ent32_p;
351 } u;
352 int nr_bhs;
353 struct buffer_head *bhs[2];
354 struct inode *fat_inode;
355};
356
357static inline void fatent_init(struct fat_entry *fatent)
358{
359 fatent->nr_bhs = 0;
360 fatent->entry = 0;
361 fatent->u.ent32_p = NULL;
362 fatent->bhs[0] = fatent->bhs[1] = NULL;
363 fatent->fat_inode = NULL;
364}
365
366static inline void fatent_set_entry(struct fat_entry *fatent, int entry)
367{
368 fatent->entry = entry;
369 fatent->u.ent32_p = NULL;
370}
371
372static inline void fatent_brelse(struct fat_entry *fatent)
373{
374 int i;
375 fatent->u.ent32_p = NULL;
376 for (i = 0; i < fatent->nr_bhs; i++)
377 brelse(bh: fatent->bhs[i]);
378 fatent->nr_bhs = 0;
379 fatent->bhs[0] = fatent->bhs[1] = NULL;
380 fatent->fat_inode = NULL;
381}
382
383static inline bool fat_valid_entry(struct msdos_sb_info *sbi, int entry)
384{
385 return FAT_START_ENT <= entry && entry < sbi->max_cluster;
386}
387
388extern void fat_ent_access_init(struct super_block *sb);
389extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
390 int entry);
391extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
392 int new, int wait);
393extern int fat_alloc_clusters(struct inode *inode, int *cluster,
394 int nr_cluster);
395extern int fat_free_clusters(struct inode *inode, int cluster);
396extern int fat_count_free_clusters(struct super_block *sb);
397extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range);
398
399/* fat/file.c */
400extern long fat_generic_ioctl(struct file *filp, unsigned int cmd,
401 unsigned long arg);
402extern const struct file_operations fat_file_operations;
403extern const struct inode_operations fat_file_inode_operations;
404extern int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
405 struct iattr *attr);
406extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
407extern int fat_getattr(struct mnt_idmap *idmap,
408 const struct path *path, struct kstat *stat,
409 u32 request_mask, unsigned int flags);
410extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
411 int datasync);
412
413/* fat/inode.c */
414extern int fat_block_truncate_page(struct inode *inode, loff_t from);
415extern void fat_attach(struct inode *inode, loff_t i_pos);
416extern void fat_detach(struct inode *inode);
417extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
418extern struct inode *fat_build_inode(struct super_block *sb,
419 struct msdos_dir_entry *de, loff_t i_pos);
420extern int fat_sync_inode(struct inode *inode);
421extern int fat_fill_super(struct super_block *sb, struct fs_context *fc,
422 void (*setup)(struct super_block *));
423extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
424
425extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
426 struct inode *i2);
427
428extern const struct fs_parameter_spec fat_param_spec[];
429int fat_init_fs_context(struct fs_context *fc, bool is_vfat);
430void fat_free_fc(struct fs_context *fc);
431
432int fat_parse_param(struct fs_context *fc, struct fs_parameter *param,
433 bool is_vfat);
434int fat_reconfigure(struct fs_context *fc);
435
436static inline unsigned long fat_dir_hash(int logstart)
437{
438 return hash_32(val: logstart, FAT_HASH_BITS);
439}
440extern int fat_add_cluster(struct inode *inode);
441
442/* fat/misc.c */
443extern __printf(3, 4) __cold
444void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...);
445#define fat_fs_error(sb, fmt, args...) \
446 __fat_fs_error(sb, 1, fmt , ## args)
447#define fat_fs_error_ratelimit(sb, fmt, args...) \
448 __fat_fs_error(sb, __ratelimit(&MSDOS_SB(sb)->ratelimit), fmt , ## args)
449
450#define FAT_PRINTK_PREFIX "%sFAT-fs (%s): "
451#define fat_msg(sb, level, fmt, args...) \
452do { \
453 printk_index_subsys_emit(FAT_PRINTK_PREFIX, level, fmt, ##args);\
454 _fat_msg(sb, level, fmt, ##args); \
455} while (0)
456__printf(3, 4) __cold
457void _fat_msg(struct super_block *sb, const char *level, const char *fmt, ...);
458#define fat_msg_ratelimit(sb, level, fmt, args...) \
459 do { \
460 if (__ratelimit(&MSDOS_SB(sb)->ratelimit)) \
461 fat_msg(sb, level, fmt, ## args); \
462 } while (0)
463extern int fat_clusters_flush(struct super_block *sb);
464extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
465extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
466 __le16 __time, __le16 __date, u8 time_cs);
467extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
468 __le16 *time, __le16 *date, u8 *time_cs);
469extern struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
470 const struct timespec64 *ts);
471extern struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
472 const struct timespec64 *ts);
473extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
474 int flags);
475extern int fat_update_time(struct inode *inode, int flags);
476extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
477
478int fat_cache_init(void);
479void fat_cache_destroy(void);
480
481/* fat/nfs.c */
482extern const struct export_operations fat_export_ops;
483extern const struct export_operations fat_export_ops_nostale;
484
485/* helper for printk */
486typedef unsigned long long llu;
487
488#endif /* !_FAT_H */
489

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source code of linux/fs/fat/fat.h