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 timespec64 i_crtime;	/* File creation (birth) time */
130	struct inode vfs_inode;
131};
132
133struct 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
141static 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 */
150static inline bool is_fat12(const struct msdos_sb_info *sbi)
151{
152	return sbi->fat_bits == 12;
153}
154
155static inline bool is_fat16(const struct msdos_sb_info *sbi)
156{
157	return sbi->fat_bits == 16;
158}
159
160static inline bool is_fat32(const struct msdos_sb_info *sbi)
161{
162	return sbi->fat_bits == 32;
163}
164
165/* Maximum number of clusters */
166static 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
174static 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 */
186static 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. */
204static 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 */
217static 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
227static 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
235static 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
246static 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
252static 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
259static 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
273static 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
285static 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
294static 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
300static 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 */
315extern void fat_cache_inval_inode(struct inode *inode);
316extern int fat_get_cluster(struct inode *inode, int cluster,
317			   int *fclus, int *dclus);
318extern int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
319				  sector_t last_block,
320				  unsigned long *mapped_blocks, sector_t *bmap);
321extern 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 */
325extern const struct file_operations fat_dir_operations;
326extern int fat_search_long(struct inode *inode, const unsigned char *name,
327			   int name_len, struct fat_slot_info *sinfo);
328extern int fat_dir_empty(struct inode *dir);
329extern int fat_subdirs(struct inode *dir);
330extern int fat_scan(struct inode *dir, const unsigned char *name,
331		    struct fat_slot_info *sinfo);
332extern int fat_scan_logstart(struct inode *dir, int i_logstart,
333			     struct fat_slot_info *sinfo);
334extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
335				struct msdos_dir_entry **de);
336extern int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts);
337extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
338			   struct fat_slot_info *sinfo);
339extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo);
340
341/* fat/fatent.c */
342struct 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
354static 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
363static inline void fatent_set_entry(struct fat_entry *fatent, int entry)
364{
365	fatent->entry = entry;
366	fatent->u.ent32_p = NULL;
367}
368
369static 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
380static 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
385extern void fat_ent_access_init(struct super_block *sb);
386extern int fat_ent_read(struct inode *inode, struct fat_entry *fatent,
387			int entry);
388extern int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
389			 int new, int wait);
390extern int fat_alloc_clusters(struct inode *inode, int *cluster,
391			      int nr_cluster);
392extern int fat_free_clusters(struct inode *inode, int cluster);
393extern int fat_count_free_clusters(struct super_block *sb);
394extern int fat_trim_fs(struct inode *inode, struct fstrim_range *range);
395
396/* fat/file.c */
397extern long fat_generic_ioctl(struct file *filp, unsigned int cmd,
398			      unsigned long arg);
399extern const struct file_operations fat_file_operations;
400extern const struct inode_operations fat_file_inode_operations;
401extern int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
402		       struct iattr *attr);
403extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
404extern int fat_getattr(struct mnt_idmap *idmap,
405		       const struct path *path, struct kstat *stat,
406		       u32 request_mask, unsigned int flags);
407extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
408			  int datasync);
409
410/* fat/inode.c */
411extern int fat_block_truncate_page(struct inode *inode, loff_t from);
412extern void fat_attach(struct inode *inode, loff_t i_pos);
413extern void fat_detach(struct inode *inode);
414extern struct inode *fat_iget(struct super_block *sb, loff_t i_pos);
415extern struct inode *fat_build_inode(struct super_block *sb,
416			struct msdos_dir_entry *de, loff_t i_pos);
417extern int fat_sync_inode(struct inode *inode);
418extern int fat_fill_super(struct super_block *sb, void *data, int silent,
419			  int isvfat, void (*setup)(struct super_block *));
420extern int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
421
422extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
423			    struct inode *i2);
424static inline unsigned long fat_dir_hash(int logstart)
425{
426	return hash_32(logstart, FAT_HASH_BITS);
427}
428extern int fat_add_cluster(struct inode *inode);
429
430/* fat/misc.c */
431extern __printf(3, 4) __cold
432void __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...)				\
440do {									\
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
445void _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)
451extern int fat_clusters_flush(struct super_block *sb);
452extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
453extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
454			      __le16 __time, __le16 __date, u8 time_cs);
455extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
456			      __le16 *time, __le16 *date, u8 *time_cs);
457extern struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
458					    const struct timespec64 *ts);
459extern struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
460					    const struct timespec64 *ts);
461extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
462			     int flags);
463extern int fat_update_time(struct inode *inode, int flags);
464extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
465
466int fat_cache_init(void);
467void fat_cache_destroy(void);
468
469/* fat/nfs.c */
470extern const struct export_operations fat_export_ops;
471extern const struct export_operations fat_export_ops_nostale;
472
473/* helper for printk */
474typedef unsigned long long	llu;
475
476#endif /* !_FAT_H */
477