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Linux/fs/fat/misc.c

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  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  * truncate the various times with appropriate granularity:
276  *   root inode:
277  *     all times always 0
278  *   all other inodes:
279  *     mtime - 2 seconds
280  *     ctime
281  *       msdos - 2 seconds
282  *       vfat  - 10 milliseconds
283  *     atime - 24 hours (00:00:00 in local timezone)
284  */
285 int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
286 {
287         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
288         struct timespec64 ts;
289 
290         if (inode->i_ino == MSDOS_ROOT_INO)
291                 return 0;
292 
293         if (now == NULL) {
294                 now = &ts;
295                 ts = current_time(inode);
296         }
297 
298         if (flags & S_ATIME) {
299                 /* to localtime */
300                 time64_t seconds = now->tv_sec - fat_tz_offset(sbi);
301                 s32 remainder;
302 
303                 div_s64_rem(seconds, SECS_PER_DAY, &remainder);
304                 /* to day boundary, and back to unix time */
305                 seconds = seconds + fat_tz_offset(sbi) - remainder;
306 
307                 inode->i_atime = (struct timespec64){ seconds, 0 };
308         }
309         if (flags & S_CTIME) {
310                 if (sbi->options.isvfat)
311                         inode->i_ctime = timespec64_trunc(*now, 10000000);
312                 else
313                         inode->i_ctime = fat_timespec64_trunc_2secs(*now);
314         }
315         if (flags & S_MTIME)
316                 inode->i_mtime = fat_timespec64_trunc_2secs(*now);
317 
318         return 0;
319 }
320 EXPORT_SYMBOL_GPL(fat_truncate_time);
321 
322 int fat_update_time(struct inode *inode, struct timespec64 *now, int flags)
323 {
324         int iflags = I_DIRTY_TIME;
325         bool dirty = false;
326 
327         if (inode->i_ino == MSDOS_ROOT_INO)
328                 return 0;
329 
330         fat_truncate_time(inode, now, flags);
331         if (flags & S_VERSION)
332                 dirty = inode_maybe_inc_iversion(inode, false);
333         if ((flags & (S_ATIME | S_CTIME | S_MTIME)) &&
334             !(inode->i_sb->s_flags & SB_LAZYTIME))
335                 dirty = true;
336 
337         if (dirty)
338                 iflags |= I_DIRTY_SYNC;
339         __mark_inode_dirty(inode, iflags);
340         return 0;
341 }
342 EXPORT_SYMBOL_GPL(fat_update_time);
343 
344 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
345 {
346         int i, err = 0;
347 
348         for (i = 0; i < nr_bhs; i++)
349                 write_dirty_buffer(bhs[i], 0);
350 
351         for (i = 0; i < nr_bhs; i++) {
352                 wait_on_buffer(bhs[i]);
353                 if (!err && !buffer_uptodate(bhs[i]))
354                         err = -EIO;
355         }
356         return err;
357 }
358 

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