aboutsummaryrefslogtreecommitdiffstats
path: root/fs/fat/misc.c
blob: 0f55f5cb732f24078af99a605e4fa764eabad6bf (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
/*
 *  linux/fs/fat/misc.c
 *
 *  Written 1992,1993 by Werner Almesberger
 *  22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
 *		 and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include "fat.h"

/*
 * fat_fs_error reports a file system problem that might indicate fa data
 * corruption/inconsistency. Depending on 'errors' mount option the
 * panic() is called, or error message is printed FAT and nothing is done,
 * or filesystem is remounted read-only (default behavior).
 * In case the file system is remounted read-only, it can be made writable
 * again by remounting it.
 */
void fat_fs_error(struct super_block *s, const char *fmt, ...)
{
	struct fat_mount_options *opts = &MSDOS_SB(s)->options;
	va_list args;

	printk(KERN_ERR "FAT: Filesystem error (dev %s)\n", s->s_id);

	printk(KERN_ERR "    ");
	va_start(args, fmt);
	vprintk(fmt, args);
	va_end(args);
	printk("\n");

	if (opts->errors == FAT_ERRORS_PANIC)
		panic("    FAT fs panic from previous error\n");
	else if (opts->errors == FAT_ERRORS_RO && !(s->s_flags & MS_RDONLY)) {
		s->s_flags |= MS_RDONLY;
		printk(KERN_ERR "    File system has been set read-only\n");
	}
}
EXPORT_SYMBOL_GPL(fat_fs_error);

/* Flushes the number of free clusters on FAT32 */
/* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
int fat_clusters_flush(struct super_block *sb)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct buffer_head *bh;
	struct fat_boot_fsinfo *fsinfo;

	if (sbi->fat_bits != 32)
		return 0;

	bh = sb_bread(sb, sbi->fsinfo_sector);
	if (bh == NULL) {
		printk(KERN_ERR "FAT: bread failed in fat_clusters_flush\n");
		return -EIO;
	}

	fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
	/* Sanity check */
	if (!IS_FSINFO(fsinfo)) {
		printk(KERN_ERR "FAT: Invalid FSINFO signature: "
		       "0x%08x, 0x%08x (sector = %lu)\n",
		       le32_to_cpu(fsinfo->signature1),
		       le32_to_cpu(fsinfo->signature2),
		       sbi->fsinfo_sector);
	} else {
		if (sbi->free_clusters != -1)
			fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
		if (sbi->prev_free != -1)
			fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
		mark_buffer_dirty(bh);
	}
	brelse(bh);

	return 0;
}

/*
 * fat_chain_add() adds a new cluster to the chain of clusters represented
 * by inode.
 */
int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	int ret, new_fclus, last;

	/*
	 * We must locate the last cluster of the file to add this new
	 * one (new_dclus) to the end of the link list (the FAT).
	 */
	last = new_fclus = 0;
	if (MSDOS_I(inode)->i_start) {
		int fclus, dclus;

		ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
		if (ret < 0)
			return ret;
		new_fclus = fclus + 1;
		last = dclus;
	}

	/* add new one to the last of the cluster chain */
	if (last) {
		struct fat_entry fatent;

		fatent_init(&fatent);
		ret = fat_ent_read(inode, &fatent, last);
		if (ret >= 0) {
			int wait = inode_needs_sync(inode);
			ret = fat_ent_write(inode, &fatent, new_dclus, wait);
			fatent_brelse(&fatent);
		}
		if (ret < 0)
			return ret;
//		fat_cache_add(inode, new_fclus, new_dclus);
	} else {
		MSDOS_I(inode)->i_start = new_dclus;
		MSDOS_I(inode)->i_logstart = new_dclus;
		/*
		 * Since generic_write_sync() synchronizes regular files later,
		 * we sync here only directories.
		 */
		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
			ret = fat_sync_inode(inode);
			if (ret)
				return ret;
		} else
			mark_inode_dirty(inode);
	}
	if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
		fat_fs_error(sb, "clusters badly computed (%d != %llu)",
			     new_fclus,
			     (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
		fat_cache_inval_inode(inode);
	}
	inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);

	return 0;
}

extern struct timezone sys_tz;

/*
 * The epoch of FAT timestamp is 1980.
 *     :  bits :     value
 * date:  0 -  4: day	(1 -  31)
 * date:  5 -  8: month	(1 -  12)
 * date:  9 - 15: year	(0 - 127) from 1980
 * time:  0 -  4: sec	(0 -  29) 2sec counts
 * time:  5 - 10: min	(0 -  59)
 * time: 11 - 15: hour	(0 -  23)
 */
#define SECS_PER_MIN	60
#define SECS_PER_HOUR	(60 * 60)
#define SECS_PER_DAY	(SECS_PER_HOUR * 24)
#define UNIX_SECS_1980	315532800L
#if BITS_PER_LONG == 64
#define UNIX_SECS_2108	4354819200L
#endif
/* days between 1.1.70 and 1.1.80 (2 leap days) */
#define DAYS_DELTA	(365 * 10 + 2)
/* 120 (2100 - 1980) isn't leap year */
#define YEAR_2100	120
#define IS_LEAP_YEAR(y)	(!((y) & 3) && (y) != YEAR_2100)

/* Linear day numbers of the respective 1sts in non-leap years. */
static time_t days_in_year[] = {
	/* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
	0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
};

/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
		       __le16 __time, __le16 __date, u8 time_cs)
{
	u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
	time_t second, day, leap_day, month, year;

	year  = date >> 9;
	month = max(1, (date >> 5) & 0xf);
	day   = max(1, date & 0x1f) - 1;

	leap_day = (year + 3) / 4;
	if (year > YEAR_2100)		/* 2100 isn't leap year */
		leap_day--;
	if (IS_LEAP_YEAR(year) && month > 2)
		leap_day++;

	second =  (time & 0x1f) << 1;
	second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
	second += (time >> 11) * SECS_PER_HOUR;
	second += (year * 365 + leap_day
		   + days_in_year[month] + day
		   + DAYS_DELTA) * SECS_PER_DAY;

	if (!sbi->options.tz_utc)
		second += sys_tz.tz_minuteswest * SECS_PER_MIN;

	if (time_cs) {
		ts->tv_sec = second + (time_cs / 100);
		ts->tv_nsec = (time_cs % 100) * 10000000;
	} else {
		ts->tv_sec = second;
		ts->tv_nsec = 0;
	}
}

/* Convert linear UNIX date to a FAT time/date pair. */
void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
		       __le16 *time, __le16 *date, u8 *time_cs)
{
	time_t second = ts->tv_sec;
	time_t day, leap_day, month, year;

	if (!sbi->options.tz_utc)
		second -= sys_tz.tz_minuteswest * SECS_PER_MIN;

	/* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
	if (second < UNIX_SECS_1980) {
		*time = 0;
		*date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
		if (time_cs)
			*time_cs = 0;
		return;
	}
#if BITS_PER_LONG == 64
	if (second >= UNIX_SECS_2108) {
		*time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
		*date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
		if (time_cs)
			*time_cs = 199;
		return;
	}
#endif

	day = second / SECS_PER_DAY - DAYS_DELTA;
	year = day / 365;
	leap_day = (year + 3) / 4;
	if (year > YEAR_2100)		/* 2100 isn't leap year */
		leap_day--;
	if (year * 365 + leap_day > day)
		year--;
	leap_day = (year + 3) / 4;
	if (year > YEAR_2100)		/* 2100 isn't leap year */
		leap_day--;
	day -= year * 365 + leap_day;

	if (IS_LEAP_YEAR(year) && day == days_in_year[3]) {
		month = 2;
	} else {
		if (IS_LEAP_YEAR(year) && day > days_in_year[3])
			day--;
		for (month = 1; month < 12; month++) {
			if (days_in_year[month + 1] > day)
				break;
		}
	}
	day -= days_in_year[month];

	*time = cpu_to_le16(((second / SECS_PER_HOUR) % 24) << 11
			    | ((second / SECS_PER_MIN) % 60) << 5
			    | (second % SECS_PER_MIN) >> 1);
	*date = cpu_to_le16((year << 9) | (month << 5) | (day + 1));
	if (time_cs)
		*time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
}
EXPORT_SYMBOL_GPL(fat_time_unix2fat);

int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
{
	int i, err = 0;

	ll_rw_block(SWRITE, nr_bhs, bhs);
	for (i = 0; i < nr_bhs; i++) {
		wait_on_buffer(bhs[i]);
		if (buffer_eopnotsupp(bhs[i])) {
			clear_buffer_eopnotsupp(bhs[i]);
			err = -EOPNOTSUPP;
		} else if (!err && !buffer_uptodate(bhs[i]))
			err = -EIO;
	}
	return err;
}