xref: /openbmc/linux/fs/fat/fat.h (revision 3ddc8b84)
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 timespec64 i_crtime;	/* File creation (birth) time */
130 	struct inode vfs_inode;
131 };
132 
133 struct fat_slot_info {
134 	loff_t i_pos;		/* on-disk position of directory entry */
135 	loff_t slot_off;	/* offset for slot or de start */
136 	int nr_slots;		/* number of slots + 1(de) in filename */
137 	struct msdos_dir_entry *de;
138 	struct buffer_head *bh;
139 };
140 
141 static inline struct msdos_sb_info *MSDOS_SB(struct super_block *sb)
142 {
143 	return sb->s_fs_info;
144 }
145 
146 /*
147  * Functions that determine the variant of the FAT file system (i.e.,
148  * whether this is FAT12, FAT16 or FAT32.
149  */
150 static inline bool is_fat12(const struct msdos_sb_info *sbi)
151 {
152 	return sbi->fat_bits == 12;
153 }
154 
155 static inline bool is_fat16(const struct msdos_sb_info *sbi)
156 {
157 	return sbi->fat_bits == 16;
158 }
159 
160 static inline bool is_fat32(const struct msdos_sb_info *sbi)
161 {
162 	return sbi->fat_bits == 32;
163 }
164 
165 /* Maximum number of clusters */
166 static inline u32 max_fat(struct super_block *sb)
167 {
168 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
169 
170 	return is_fat32(sbi) ? MAX_FAT32 :
171 		is_fat16(sbi) ? MAX_FAT16 : MAX_FAT12;
172 }
173 
174 static inline struct msdos_inode_info *MSDOS_I(struct inode *inode)
175 {
176 	return container_of(inode, struct msdos_inode_info, vfs_inode);
177 }
178 
179 /*
180  * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to
181  * save ATTR_RO instead of ->i_mode.
182  *
183  * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only
184  * bit, it's just used as flag for app.
185  */
186 static inline int fat_mode_can_hold_ro(struct inode *inode)
187 {
188 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
189 	umode_t mask;
190 
191 	if (S_ISDIR(inode->i_mode)) {
192 		if (!sbi->options.rodir)
193 			return 0;
194 		mask = ~sbi->options.fs_dmask;
195 	} else
196 		mask = ~sbi->options.fs_fmask;
197 
198 	if (!(mask & S_IWUGO))
199 		return 0;
200 	return 1;
201 }
202 
203 /* Convert attribute bits and a mask to the UNIX mode. */
204 static inline umode_t fat_make_mode(struct msdos_sb_info *sbi,
205 				   u8 attrs, umode_t mode)
206 {
207 	if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir))
208 		mode &= ~S_IWUGO;
209 
210 	if (attrs & ATTR_DIR)
211 		return (mode & ~sbi->options.fs_dmask) | S_IFDIR;
212 	else
213 		return (mode & ~sbi->options.fs_fmask) | S_IFREG;
214 }
215 
216 /* Return the FAT attribute byte for this inode */
217 static inline u8 fat_make_attrs(struct inode *inode)
218 {
219 	u8 attrs = MSDOS_I(inode)->i_attrs;
220 	if (S_ISDIR(inode->i_mode))
221 		attrs |= ATTR_DIR;
222 	if (fat_mode_can_hold_ro(inode) && !(inode->i_mode & S_IWUGO))
223 		attrs |= ATTR_RO;
224 	return attrs;
225 }
226 
227 static inline void fat_save_attrs(struct inode *inode, u8 attrs)
228 {
229 	if (fat_mode_can_hold_ro(inode))
230 		MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED;
231 	else
232 		MSDOS_I(inode)->i_attrs = attrs & (ATTR_UNUSED | ATTR_RO);
233 }
234 
235 static inline unsigned char fat_checksum(const __u8 *name)
236 {
237 	unsigned char s = name[0];
238 	s = (s<<7) + (s>>1) + name[1];	s = (s<<7) + (s>>1) + name[2];
239 	s = (s<<7) + (s>>1) + name[3];	s = (s<<7) + (s>>1) + name[4];
240 	s = (s<<7) + (s>>1) + name[5];	s = (s<<7) + (s>>1) + name[6];
241 	s = (s<<7) + (s>>1) + name[7];	s = (s<<7) + (s>>1) + name[8];
242 	s = (s<<7) + (s>>1) + name[9];	s = (s<<7) + (s>>1) + name[10];
243 	return s;
244 }
245 
246 static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus)
247 {
248 	return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus
249 		+ sbi->data_start;
250 }
251 
252 static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi,
253 				loff_t i_pos, sector_t *blknr, int *offset)
254 {
255 	*blknr = i_pos >> sbi->dir_per_block_bits;
256 	*offset = i_pos & (sbi->dir_per_block - 1);
257 }
258 
259 static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
260 					struct inode *inode)
261 {
262 	loff_t i_pos;
263 #if BITS_PER_LONG == 32
264 	spin_lock(&sbi->inode_hash_lock);
265 #endif
266 	i_pos = MSDOS_I(inode)->i_pos;
267 #if BITS_PER_LONG == 32
268 	spin_unlock(&sbi->inode_hash_lock);
269 #endif
270 	return i_pos;
271 }
272 
273 static inline void fat16_towchar(wchar_t *dst, const __u8 *src, size_t len)
274 {
275 #ifdef __BIG_ENDIAN
276 	while (len--) {
277 		*dst++ = src[0] | (src[1] << 8);
278 		src += 2;
279 	}
280 #else
281 	memcpy(dst, src, len * 2);
282 #endif
283 }
284 
285 static inline int fat_get_start(const struct msdos_sb_info *sbi,
286 				const struct msdos_dir_entry *de)
287 {
288 	int cluster = le16_to_cpu(de->start);
289 	if (is_fat32(sbi))
290 		cluster |= (le16_to_cpu(de->starthi) << 16);
291 	return cluster;
292 }
293 
294 static inline void fat_set_start(struct msdos_dir_entry *de, int cluster)
295 {
296 	de->start   = cpu_to_le16(cluster);
297 	de->starthi = cpu_to_le16(cluster >> 16);
298 }
299 
300 static inline void fatwchar_to16(__u8 *dst, const wchar_t *src, size_t len)
301 {
302 #ifdef __BIG_ENDIAN
303 	while (len--) {
304 		dst[0] = *src & 0x00FF;
305 		dst[1] = (*src & 0xFF00) >> 8;
306 		dst += 2;
307 		src++;
308 	}
309 #else
310 	memcpy(dst, src, len * 2);
311 #endif
312 }
313 
314 /* fat/cache.c */
315 extern void fat_cache_inval_inode(struct inode *inode);
316 extern int fat_get_cluster(struct inode *inode, int cluster,
317 			   int *fclus, int *dclus);
318 extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
319 				  sector_t last_block,
320 				  unsigned long *mapped_blocks, sector_t *bmap);
321 extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
322 		    unsigned long *mapped_blocks, int create, bool from_bmap);
323 
324 /* fat/dir.c */
325 extern const struct file_operations fat_dir_operations;
326 extern int fat_search_long(struct inode *inode, const unsigned char *name,
327 			   int name_len, struct fat_slot_info *sinfo);
328 extern int fat_dir_empty(struct inode *dir);
329 extern int fat_subdirs(struct inode *dir);
330 extern int fat_scan(struct inode *dir, const unsigned char *name,
331 		    struct fat_slot_info *sinfo);
332 extern int fat_scan_logstart(struct inode *dir, int i_logstart,
333 			     struct fat_slot_info *sinfo);
334 extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
335 				struct msdos_dir_entry **de);
336 extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts);
337 extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
338 			   struct fat_slot_info *sinfo);
339 extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo);
340 
341 /* fat/fatent.c */
342 struct fat_entry {
343 	int entry;
344 	union {
345 		u8 *ent12_p[2];
346 		__le16 *ent16_p;
347 		__le32 *ent32_p;
348 	} u;
349 	int nr_bhs;
350 	struct buffer_head *bhs[2];
351 	struct inode *fat_inode;
352 };
353 
354 static inline void fatent_init(struct fat_entry *fatent)
355 {
356 	fatent->nr_bhs = 0;
357 	fatent->entry = 0;
358 	fatent->u.ent32_p = NULL;
359 	fatent->bhs[0] = fatent->bhs[1] = NULL;
360 	fatent->fat_inode = NULL;
361 }
362 
363 static inline void fatent_set_entry(struct fat_entry *fatent, int entry)
364 {
365 	fatent->entry = entry;
366 	fatent->u.ent32_p = NULL;
367 }
368 
369 static inline void fatent_brelse(struct fat_entry *fatent)
370 {
371 	int i;
372 	fatent->u.ent32_p = NULL;
373 	for (i = 0; i < fatent->nr_bhs; i++)
374 		brelse(fatent->bhs[i]);
375 	fatent->nr_bhs = 0;
376 	fatent->bhs[0] = fatent->bhs[1] = NULL;
377 	fatent->fat_inode = NULL;
378 }
379 
380 static inline bool fat_valid_entry(struct msdos_sb_info *sbi, int entry)
381 {
382 	return FAT_START_ENT <= entry && entry < sbi->max_cluster;
383 }
384 
385 extern void fat_ent_access_init(struct super_block *sb);
386 extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
387 			int entry);
388 extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
389 			 int new, int wait);
390 extern int fat_alloc_clusters(struct inode *inode, int *cluster,
391 			      int nr_cluster);
392 extern int fat_free_clusters(struct inode *inode, int cluster);
393 extern int fat_count_free_clusters(struct super_block *sb);
394 extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range);
395 
396 /* fat/file.c */
397 extern long fat_generic_ioctl(struct file *filp, unsigned int cmd,
398 			      unsigned long arg);
399 extern const struct file_operations fat_file_operations;
400 extern const struct inode_operations fat_file_inode_operations;
401 extern int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
402 		       struct iattr *attr);
403 extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
404 extern int fat_getattr(struct mnt_idmap *idmap,
405 		       const struct path *path, struct kstat *stat,
406 		       u32 request_mask, unsigned int flags);
407 extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
408 			  int datasync);
409 
410 /* fat/inode.c */
411 extern int fat_block_truncate_page(struct inode *inode, loff_t from);
412 extern void fat_attach(struct inode *inode, loff_t i_pos);
413 extern void fat_detach(struct inode *inode);
414 extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
415 extern struct inode *fat_build_inode(struct super_block *sb,
416 			struct msdos_dir_entry *de, loff_t i_pos);
417 extern int fat_sync_inode(struct inode *inode);
418 extern int fat_fill_super(struct super_block *sb, void *data, int silent,
419 			  int isvfat, void (*setup)(struct super_block *));
420 extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
421 
422 extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
423 			    struct inode *i2);
424 static inline unsigned long fat_dir_hash(int logstart)
425 {
426 	return hash_32(logstart, FAT_HASH_BITS);
427 }
428 extern int fat_add_cluster(struct inode *inode);
429 
430 /* fat/misc.c */
431 extern __printf(3, 4) __cold
432 void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...);
433 #define fat_fs_error(sb, fmt, args...)		\
434 	__fat_fs_error(sb, 1, fmt , ## args)
435 #define fat_fs_error_ratelimit(sb, fmt, args...) \
436 	__fat_fs_error(sb, __ratelimit(&MSDOS_SB(sb)->ratelimit), fmt , ## args)
437 
438 #define FAT_PRINTK_PREFIX "%sFAT-fs (%s): "
439 #define fat_msg(sb, level, fmt, args...)				\
440 do {									\
441 	printk_index_subsys_emit(FAT_PRINTK_PREFIX, level, fmt, ##args);\
442 	_fat_msg(sb, level, fmt, ##args);				\
443 } while (0)
444 __printf(3, 4) __cold
445 void _fat_msg(struct super_block *sb, const char *level, const char *fmt, ...);
446 #define fat_msg_ratelimit(sb, level, fmt, args...)	\
447 	do {	\
448 			if (__ratelimit(&MSDOS_SB(sb)->ratelimit))	\
449 				fat_msg(sb, level, fmt, ## args);	\
450 	 } while (0)
451 extern int fat_clusters_flush(struct super_block *sb);
452 extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
453 extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
454 			      __le16 __time, __le16 __date, u8 time_cs);
455 extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
456 			      __le16 *time, __le16 *date, u8 *time_cs);
457 extern struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
458 					    const struct timespec64 *ts);
459 extern struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
460 					    const struct timespec64 *ts);
461 extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
462 			     int flags);
463 extern int fat_update_time(struct inode *inode, int flags);
464 extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
465 
466 int fat_cache_init(void);
467 void fat_cache_destroy(void);
468 
469 /* fat/nfs.c */
470 extern const struct export_operations fat_export_ops;
471 extern const struct export_operations fat_export_ops_nostale;
472 
473 /* helper for printk */
474 typedef unsigned long long	llu;
475 
476 #endif /* !_FAT_H */
477