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 */
__fat_fs_error(struct super_block * sb,int report,const char * fmt,...)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 a preformatted FAT message based on a superblock.
46 * @sb: A pointer to a &struct super_block
47 * @level: A Kernel printk level constant
48 * @fmt: The printf-style format string to print.
49 *
50 * Everything that is not fat_fs_error() should be fat_msg().
51 *
52 * fat_msg() wraps _fat_msg() for printk indexing.
53 */
_fat_msg(struct super_block * sb,const char * level,const char * fmt,...)54 void _fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
55 {
56 struct va_format vaf;
57 va_list args;
58
59 va_start(args, fmt);
60 vaf.fmt = fmt;
61 vaf.va = &args;
62 _printk(FAT_PRINTK_PREFIX "%pV\n", level, sb->s_id, &vaf);
63 va_end(args);
64 }
65
66 /* Flushes the number of free clusters on FAT32 */
67 /* XXX: Need to write one per FSINFO block. Currently only writes 1 */
fat_clusters_flush(struct super_block * sb)68 int fat_clusters_flush(struct super_block *sb)
69 {
70 struct msdos_sb_info *sbi = MSDOS_SB(sb);
71 struct buffer_head *bh;
72 struct fat_boot_fsinfo *fsinfo;
73
74 if (!is_fat32(sbi))
75 return 0;
76
77 bh = sb_bread(sb, sbi->fsinfo_sector);
78 if (bh == NULL) {
79 fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
80 return -EIO;
81 }
82
83 fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
84 /* Sanity check */
85 if (!IS_FSINFO(fsinfo)) {
86 fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
87 "0x%08x, 0x%08x (sector = %lu)",
88 le32_to_cpu(fsinfo->signature1),
89 le32_to_cpu(fsinfo->signature2),
90 sbi->fsinfo_sector);
91 } else {
92 if (sbi->free_clusters != -1)
93 fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
94 if (sbi->prev_free != -1)
95 fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
96 mark_buffer_dirty(bh);
97 }
98 brelse(bh);
99
100 return 0;
101 }
102
103 /*
104 * fat_chain_add() adds a new cluster to the chain of clusters represented
105 * by inode.
106 */
fat_chain_add(struct inode * inode,int new_dclus,int nr_cluster)107 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
108 {
109 struct super_block *sb = inode->i_sb;
110 struct msdos_sb_info *sbi = MSDOS_SB(sb);
111 int ret, new_fclus, last;
112
113 /*
114 * We must locate the last cluster of the file to add this new
115 * one (new_dclus) to the end of the link list (the FAT).
116 */
117 last = new_fclus = 0;
118 if (MSDOS_I(inode)->i_start) {
119 int fclus, dclus;
120
121 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
122 if (ret < 0)
123 return ret;
124 new_fclus = fclus + 1;
125 last = dclus;
126 }
127
128 /* add new one to the last of the cluster chain */
129 if (last) {
130 struct fat_entry fatent;
131
132 fatent_init(&fatent);
133 ret = fat_ent_read(inode, &fatent, last);
134 if (ret >= 0) {
135 int wait = inode_needs_sync(inode);
136 int old = ret;
137
138 ret = fat_ent_write(inode, &fatent, new_dclus, wait);
139 if (ret < 0)
140 fat_ent_write(inode, &fatent, old, wait);
141 fatent_brelse(&fatent);
142 }
143 if (ret < 0)
144 return ret;
145 /*
146 * FIXME:Although we can add this cache, fat_cache_add() is
147 * assuming to be called after linear search with fat_cache_id.
148 */
149 // fat_cache_add(inode, new_fclus, new_dclus);
150 } else {
151 MSDOS_I(inode)->i_start = new_dclus;
152 MSDOS_I(inode)->i_logstart = new_dclus;
153 mark_inode_dirty(inode);
154 /*
155 * Since generic_write_sync() synchronizes regular files later,
156 * we sync here only directories.
157 */
158 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
159 ret = sync_inode_metadata(inode, 1);
160 if (ret)
161 return ret;
162 }
163
164 }
165 if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
166 fat_fs_error_ratelimit(
167 sb, "clusters badly computed (%d != %llu)", new_fclus,
168 (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
169 fat_cache_inval_inode(inode);
170 }
171 inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
172
173 return 0;
174 }
175
176 /*
177 * The epoch of FAT timestamp is 1980.
178 * : bits : value
179 * date: 0 - 4: day (1 - 31)
180 * date: 5 - 8: month (1 - 12)
181 * date: 9 - 15: year (0 - 127) from 1980
182 * time: 0 - 4: sec (0 - 29) 2sec counts
183 * time: 5 - 10: min (0 - 59)
184 * time: 11 - 15: hour (0 - 23)
185 */
186 #define SECS_PER_MIN 60
187 #define SECS_PER_HOUR (60 * 60)
188 #define SECS_PER_DAY (SECS_PER_HOUR * 24)
189 /* days between 1.1.70 and 1.1.80 (2 leap days) */
190 #define DAYS_DELTA (365 * 10 + 2)
191 /* 120 (2100 - 1980) isn't leap year */
192 #define YEAR_2100 120
193 #define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
194
195 /* Linear day numbers of the respective 1sts in non-leap years. */
196 static long days_in_year[] = {
197 /* Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec */
198 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
199 };
200
fat_tz_offset(const struct msdos_sb_info * sbi)201 static inline int fat_tz_offset(const struct msdos_sb_info *sbi)
202 {
203 return (sbi->options.tz_set ?
204 -sbi->options.time_offset :
205 sys_tz.tz_minuteswest) * SECS_PER_MIN;
206 }
207
208 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
fat_time_fat2unix(struct msdos_sb_info * sbi,struct timespec64 * ts,__le16 __time,__le16 __date,u8 time_cs)209 void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
210 __le16 __time, __le16 __date, u8 time_cs)
211 {
212 u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
213 time64_t second;
214 long day, leap_day, month, year;
215
216 year = date >> 9;
217 month = max(1, (date >> 5) & 0xf);
218 day = max(1, date & 0x1f) - 1;
219
220 leap_day = (year + 3) / 4;
221 if (year > YEAR_2100) /* 2100 isn't leap year */
222 leap_day--;
223 if (IS_LEAP_YEAR(year) && month > 2)
224 leap_day++;
225
226 second = (time & 0x1f) << 1;
227 second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
228 second += (time >> 11) * SECS_PER_HOUR;
229 second += (time64_t)(year * 365 + leap_day
230 + days_in_year[month] + day
231 + DAYS_DELTA) * SECS_PER_DAY;
232
233 second += fat_tz_offset(sbi);
234
235 if (time_cs) {
236 ts->tv_sec = second + (time_cs / 100);
237 ts->tv_nsec = (time_cs % 100) * 10000000;
238 } else {
239 ts->tv_sec = second;
240 ts->tv_nsec = 0;
241 }
242 }
243
244 /* Export fat_time_fat2unix() for the fat_test KUnit tests. */
245 EXPORT_SYMBOL_GPL(fat_time_fat2unix);
246
247 /* Convert linear UNIX date to a FAT time/date pair. */
fat_time_unix2fat(struct msdos_sb_info * sbi,struct timespec64 * ts,__le16 * time,__le16 * date,u8 * time_cs)248 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
249 __le16 *time, __le16 *date, u8 *time_cs)
250 {
251 struct tm tm;
252 time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm);
253
254 /* FAT can only support year between 1980 to 2107 */
255 if (tm.tm_year < 1980 - 1900) {
256 *time = 0;
257 *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
258 if (time_cs)
259 *time_cs = 0;
260 return;
261 }
262 if (tm.tm_year > 2107 - 1900) {
263 *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
264 *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
265 if (time_cs)
266 *time_cs = 199;
267 return;
268 }
269
270 /* from 1900 -> from 1980 */
271 tm.tm_year -= 80;
272 /* 0~11 -> 1~12 */
273 tm.tm_mon++;
274 /* 0~59 -> 0~29(2sec counts) */
275 tm.tm_sec >>= 1;
276
277 *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
278 *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
279 if (time_cs)
280 *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
281 }
282 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
283
fat_timespec64_trunc_2secs(struct timespec64 ts)284 static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
285 {
286 return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
287 }
288
289 /*
290 * truncate atime to 24 hour granularity (00:00:00 in local timezone)
291 */
fat_truncate_atime(const struct msdos_sb_info * sbi,const struct timespec64 * ts)292 struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
293 const struct timespec64 *ts)
294 {
295 /* to localtime */
296 time64_t seconds = ts->tv_sec - fat_tz_offset(sbi);
297 s32 remainder;
298
299 div_s64_rem(seconds, SECS_PER_DAY, &remainder);
300 /* to day boundary, and back to unix time */
301 seconds = seconds + fat_tz_offset(sbi) - remainder;
302
303 return (struct timespec64){ seconds, 0 };
304 }
305 /* Export fat_truncate_atime() for the fat_test KUnit tests. */
306 EXPORT_SYMBOL_GPL(fat_truncate_atime);
307
308 /*
309 * Update the in-inode atime and/or mtime after truncating the timestamp to the
310 * granularity. All timestamps in root inode are always 0.
311 *
312 * ctime and mtime share the same on-disk field, and should be identical in
313 * memory. All mtime updates will be applied to ctime, but ctime updates are
314 * ignored.
315 */
fat_truncate_time(struct inode * inode,struct timespec64 * now,unsigned int flags)316 void fat_truncate_time(struct inode *inode, struct timespec64 *now,
317 unsigned int flags)
318 {
319 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
320 struct timespec64 ts;
321
322 if (inode->i_ino == MSDOS_ROOT_INO)
323 return;
324
325 if (now == NULL) {
326 now = &ts;
327 ts = current_time(inode);
328 }
329
330 if (flags & FAT_UPDATE_ATIME)
331 inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, now));
332 if (flags & FAT_UPDATE_CMTIME) {
333 /* truncate mtime to 2 second granularity */
334 struct timespec64 mtime = fat_timespec64_trunc_2secs(*now);
335
336 inode_set_mtime_to_ts(inode, mtime);
337 inode_set_ctime_to_ts(inode, mtime);
338 }
339 }
340 EXPORT_SYMBOL_GPL(fat_truncate_time);
341
fat_update_time(struct inode * inode,enum fs_update_time type,unsigned int flags)342 int fat_update_time(struct inode *inode, enum fs_update_time type,
343 unsigned int flags)
344 {
345 if (inode->i_ino != MSDOS_ROOT_INO) {
346 fat_truncate_time(inode, NULL, type == FS_UPD_ATIME ?
347 FAT_UPDATE_ATIME : FAT_UPDATE_CMTIME);
348 __mark_inode_dirty(inode, inode_time_dirty_flag(inode));
349 }
350 return 0;
351 }
352 EXPORT_SYMBOL_GPL(fat_update_time);
353
fat_sync_bhs(struct buffer_head ** bhs,int nr_bhs)354 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
355 {
356 int i, err = 0;
357
358 for (i = 0; i < nr_bhs; i++)
359 write_dirty_buffer(bhs[i], 0);
360
361 for (i = 0; i < nr_bhs; i++) {
362 wait_on_buffer(bhs[i]);
363 if (!err && buffer_write_io_error(bhs[i]))
364 err = -EIO;
365 }
366 return err;
367 }
368