xref: /openbmc/linux/fs/fat/misc.c (revision 021ed9f5)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/fs/fat/misc.c
4  *
5  *  Written 1992,1993 by Werner Almesberger
6  *  22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
7  *		 and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
8  */
9 
10 #include "fat.h"
11 #include <linux/iversion.h>
12 
13 /*
14  * fat_fs_error reports a file system problem that might indicate fa data
15  * corruption/inconsistency. Depending on 'errors' mount option the
16  * panic() is called, or error message is printed FAT and nothing is done,
17  * or filesystem is remounted read-only (default behavior).
18  * In case the file system is remounted read-only, it can be made writable
19  * again by remounting it.
20  */
21 void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
22 {
23 	struct fat_mount_options *opts = &MSDOS_SB(sb)->options;
24 	va_list args;
25 	struct va_format vaf;
26 
27 	if (report) {
28 		va_start(args, fmt);
29 		vaf.fmt = fmt;
30 		vaf.va = &args;
31 		fat_msg(sb, KERN_ERR, "error, %pV", &vaf);
32 		va_end(args);
33 	}
34 
35 	if (opts->errors == FAT_ERRORS_PANIC)
36 		panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);
37 	else if (opts->errors == FAT_ERRORS_RO && !sb_rdonly(sb)) {
38 		sb->s_flags |= SB_RDONLY;
39 		fat_msg(sb, KERN_ERR, "Filesystem has been set read-only");
40 	}
41 }
42 EXPORT_SYMBOL_GPL(__fat_fs_error);
43 
44 /**
45  * fat_msg() - print preformated FAT specific messages. Every thing what is
46  * not fat_fs_error() should be fat_msg().
47  */
48 void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
49 {
50 	struct va_format vaf;
51 	va_list args;
52 
53 	va_start(args, fmt);
54 	vaf.fmt = fmt;
55 	vaf.va = &args;
56 	printk("%sFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
57 	va_end(args);
58 }
59 
60 /* Flushes the number of free clusters on FAT32 */
61 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
62 int fat_clusters_flush(struct super_block *sb)
63 {
64 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
65 	struct buffer_head *bh;
66 	struct fat_boot_fsinfo *fsinfo;
67 
68 	if (!is_fat32(sbi))
69 		return 0;
70 
71 	bh = sb_bread(sb, sbi->fsinfo_sector);
72 	if (bh == NULL) {
73 		fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
74 		return -EIO;
75 	}
76 
77 	fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
78 	/* Sanity check */
79 	if (!IS_FSINFO(fsinfo)) {
80 		fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
81 		       "0x%08x, 0x%08x (sector = %lu)",
82 		       le32_to_cpu(fsinfo->signature1),
83 		       le32_to_cpu(fsinfo->signature2),
84 		       sbi->fsinfo_sector);
85 	} else {
86 		if (sbi->free_clusters != -1)
87 			fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
88 		if (sbi->prev_free != -1)
89 			fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
90 		mark_buffer_dirty(bh);
91 	}
92 	brelse(bh);
93 
94 	return 0;
95 }
96 
97 /*
98  * fat_chain_add() adds a new cluster to the chain of clusters represented
99  * by inode.
100  */
101 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
102 {
103 	struct super_block *sb = inode->i_sb;
104 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
105 	int ret, new_fclus, last;
106 
107 	/*
108 	 * We must locate the last cluster of the file to add this new
109 	 * one (new_dclus) to the end of the link list (the FAT).
110 	 */
111 	last = new_fclus = 0;
112 	if (MSDOS_I(inode)->i_start) {
113 		int fclus, dclus;
114 
115 		ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
116 		if (ret < 0)
117 			return ret;
118 		new_fclus = fclus + 1;
119 		last = dclus;
120 	}
121 
122 	/* add new one to the last of the cluster chain */
123 	if (last) {
124 		struct fat_entry fatent;
125 
126 		fatent_init(&fatent);
127 		ret = fat_ent_read(inode, &fatent, last);
128 		if (ret >= 0) {
129 			int wait = inode_needs_sync(inode);
130 			ret = fat_ent_write(inode, &fatent, new_dclus, wait);
131 			fatent_brelse(&fatent);
132 		}
133 		if (ret < 0)
134 			return ret;
135 		/*
136 		 * FIXME:Although we can add this cache, fat_cache_add() is
137 		 * assuming to be called after linear search with fat_cache_id.
138 		 */
139 //		fat_cache_add(inode, new_fclus, new_dclus);
140 	} else {
141 		MSDOS_I(inode)->i_start = new_dclus;
142 		MSDOS_I(inode)->i_logstart = new_dclus;
143 		/*
144 		 * Since generic_write_sync() synchronizes regular files later,
145 		 * we sync here only directories.
146 		 */
147 		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
148 			ret = fat_sync_inode(inode);
149 			if (ret)
150 				return ret;
151 		} else
152 			mark_inode_dirty(inode);
153 	}
154 	if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
155 		fat_fs_error(sb, "clusters badly computed (%d != %llu)",
156 			     new_fclus,
157 			     (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
158 		fat_cache_inval_inode(inode);
159 	}
160 	inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
161 
162 	return 0;
163 }
164 
165 /*
166  * The epoch of FAT timestamp is 1980.
167  *     :  bits :     value
168  * date:  0 -  4: day	(1 -  31)
169  * date:  5 -  8: month	(1 -  12)
170  * date:  9 - 15: year	(0 - 127) from 1980
171  * time:  0 -  4: sec	(0 -  29) 2sec counts
172  * time:  5 - 10: min	(0 -  59)
173  * time: 11 - 15: hour	(0 -  23)
174  */
175 #define SECS_PER_MIN	60
176 #define SECS_PER_HOUR	(60 * 60)
177 #define SECS_PER_DAY	(SECS_PER_HOUR * 24)
178 /* days between 1.1.70 and 1.1.80 (2 leap days) */
179 #define DAYS_DELTA	(365 * 10 + 2)
180 /* 120 (2100 - 1980) isn't leap year */
181 #define YEAR_2100	120
182 #define IS_LEAP_YEAR(y)	(!((y) & 3) && (y) != YEAR_2100)
183 
184 /* Linear day numbers of the respective 1sts in non-leap years. */
185 static long days_in_year[] = {
186 	/* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
187 	0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
188 };
189 
190 static inline int fat_tz_offset(struct msdos_sb_info *sbi)
191 {
192 	return (sbi->options.tz_set ?
193 	       -sbi->options.time_offset :
194 	       sys_tz.tz_minuteswest) * SECS_PER_MIN;
195 }
196 
197 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
198 void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
199 		       __le16 __time, __le16 __date, u8 time_cs)
200 {
201 	u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
202 	time64_t second;
203 	long day, leap_day, month, year;
204 
205 	year  = date >> 9;
206 	month = max(1, (date >> 5) & 0xf);
207 	day   = max(1, date & 0x1f) - 1;
208 
209 	leap_day = (year + 3) / 4;
210 	if (year > YEAR_2100)		/* 2100 isn't leap year */
211 		leap_day--;
212 	if (IS_LEAP_YEAR(year) && month > 2)
213 		leap_day++;
214 
215 	second =  (time & 0x1f) << 1;
216 	second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
217 	second += (time >> 11) * SECS_PER_HOUR;
218 	second += (time64_t)(year * 365 + leap_day
219 		   + days_in_year[month] + day
220 		   + DAYS_DELTA) * SECS_PER_DAY;
221 
222 	second += fat_tz_offset(sbi);
223 
224 	if (time_cs) {
225 		ts->tv_sec = second + (time_cs / 100);
226 		ts->tv_nsec = (time_cs % 100) * 10000000;
227 	} else {
228 		ts->tv_sec = second;
229 		ts->tv_nsec = 0;
230 	}
231 }
232 
233 /* Convert linear UNIX date to a FAT time/date pair. */
234 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
235 		       __le16 *time, __le16 *date, u8 *time_cs)
236 {
237 	struct tm tm;
238 	time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm);
239 
240 	/*  FAT can only support year between 1980 to 2107 */
241 	if (tm.tm_year < 1980 - 1900) {
242 		*time = 0;
243 		*date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
244 		if (time_cs)
245 			*time_cs = 0;
246 		return;
247 	}
248 	if (tm.tm_year > 2107 - 1900) {
249 		*time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
250 		*date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
251 		if (time_cs)
252 			*time_cs = 199;
253 		return;
254 	}
255 
256 	/* from 1900 -> from 1980 */
257 	tm.tm_year -= 80;
258 	/* 0~11 -> 1~12 */
259 	tm.tm_mon++;
260 	/* 0~59 -> 0~29(2sec counts) */
261 	tm.tm_sec >>= 1;
262 
263 	*time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
264 	*date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
265 	if (time_cs)
266 		*time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
267 }
268 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
269 
270 static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
271 {
272 	return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
273 }
274 
275 static inline struct timespec64 fat_timespec64_trunc_10ms(struct timespec64 ts)
276 {
277 	if (ts.tv_nsec)
278 		ts.tv_nsec -= ts.tv_nsec % 10000000UL;
279 	return ts;
280 }
281 
282 /*
283  * truncate the various times with appropriate granularity:
284  *   root inode:
285  *     all times always 0
286  *   all other inodes:
287  *     mtime - 2 seconds
288  *     ctime
289  *       msdos - 2 seconds
290  *       vfat  - 10 milliseconds
291  *     atime - 24 hours (00:00:00 in local timezone)
292  */
293 int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
294 {
295 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
296 	struct timespec64 ts;
297 
298 	if (inode->i_ino == MSDOS_ROOT_INO)
299 		return 0;
300 
301 	if (now == NULL) {
302 		now = &ts;
303 		ts = current_time(inode);
304 	}
305 
306 	if (flags & S_ATIME) {
307 		/* to localtime */
308 		time64_t seconds = now->tv_sec - fat_tz_offset(sbi);
309 		s32 remainder;
310 
311 		div_s64_rem(seconds, SECS_PER_DAY, &remainder);
312 		/* to day boundary, and back to unix time */
313 		seconds = seconds + fat_tz_offset(sbi) - remainder;
314 
315 		inode->i_atime = (struct timespec64){ seconds, 0 };
316 	}
317 	if (flags & S_CTIME) {
318 		if (sbi->options.isvfat)
319 			inode->i_ctime = fat_timespec64_trunc_10ms(*now);
320 		else
321 			inode->i_ctime = fat_timespec64_trunc_2secs(*now);
322 	}
323 	if (flags & S_MTIME)
324 		inode->i_mtime = fat_timespec64_trunc_2secs(*now);
325 
326 	return 0;
327 }
328 EXPORT_SYMBOL_GPL(fat_truncate_time);
329 
330 int fat_update_time(struct inode *inode, struct timespec64 *now, int flags)
331 {
332 	int iflags = I_DIRTY_TIME;
333 	bool dirty = false;
334 
335 	if (inode->i_ino == MSDOS_ROOT_INO)
336 		return 0;
337 
338 	fat_truncate_time(inode, now, flags);
339 	if (flags & S_VERSION)
340 		dirty = inode_maybe_inc_iversion(inode, false);
341 	if ((flags & (S_ATIME | S_CTIME | S_MTIME)) &&
342 	    !(inode->i_sb->s_flags & SB_LAZYTIME))
343 		dirty = true;
344 
345 	if (dirty)
346 		iflags |= I_DIRTY_SYNC;
347 	__mark_inode_dirty(inode, iflags);
348 	return 0;
349 }
350 EXPORT_SYMBOL_GPL(fat_update_time);
351 
352 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
353 {
354 	int i, err = 0;
355 
356 	for (i = 0; i < nr_bhs; i++)
357 		write_dirty_buffer(bhs[i], 0);
358 
359 	for (i = 0; i < nr_bhs; i++) {
360 		wait_on_buffer(bhs[i]);
361 		if (!err && !buffer_uptodate(bhs[i]))
362 			err = -EIO;
363 	}
364 	return err;
365 }
366