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TOMOYO Linux Cross Reference
Linux/fs/fat/misc.c

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  1 /*
  2  *  linux/fs/fat/misc.c
  3  *
  4  *  Written 1992,1993 by Werner Almesberger
  5  *  22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
  6  *               and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
  7  */
  8 
  9 #include <linux/module.h>
 10 #include <linux/fs.h>
 11 #include <linux/buffer_head.h>
 12 #include "fat.h"
 13 
 14 /*
 15  * fat_fs_error reports a file system problem that might indicate fa data
 16  * corruption/inconsistency. Depending on 'errors' mount option the
 17  * panic() is called, or error message is printed FAT and nothing is done,
 18  * or filesystem is remounted read-only (default behavior).
 19  * In case the file system is remounted read-only, it can be made writable
 20  * again by remounting it.
 21  */
 22 void fat_fs_error(struct super_block *s, const char *fmt, ...)
 23 {
 24         struct fat_mount_options *opts = &MSDOS_SB(s)->options;
 25         va_list args;
 26 
 27         printk(KERN_ERR "FAT: Filesystem error (dev %s)\n", s->s_id);
 28 
 29         printk(KERN_ERR "    ");
 30         va_start(args, fmt);
 31         vprintk(fmt, args);
 32         va_end(args);
 33         printk("\n");
 34 
 35         if (opts->errors == FAT_ERRORS_PANIC)
 36                 panic("    FAT fs panic from previous error\n");
 37         else if (opts->errors == FAT_ERRORS_RO && !(s->s_flags & MS_RDONLY)) {
 38                 s->s_flags |= MS_RDONLY;
 39                 printk(KERN_ERR "    File system has been set read-only\n");
 40         }
 41 }
 42 EXPORT_SYMBOL_GPL(fat_fs_error);
 43 
 44 /* Flushes the number of free clusters on FAT32 */
 45 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
 46 int fat_clusters_flush(struct super_block *sb)
 47 {
 48         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 49         struct buffer_head *bh;
 50         struct fat_boot_fsinfo *fsinfo;
 51 
 52         if (sbi->fat_bits != 32)
 53                 return 0;
 54 
 55         bh = sb_bread(sb, sbi->fsinfo_sector);
 56         if (bh == NULL) {
 57                 printk(KERN_ERR "FAT: bread failed in fat_clusters_flush\n");
 58                 return -EIO;
 59         }
 60 
 61         fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
 62         /* Sanity check */
 63         if (!IS_FSINFO(fsinfo)) {
 64                 printk(KERN_ERR "FAT: Invalid FSINFO signature: "
 65                        "0x%08x, 0x%08x (sector = %lu)\n",
 66                        le32_to_cpu(fsinfo->signature1),
 67                        le32_to_cpu(fsinfo->signature2),
 68                        sbi->fsinfo_sector);
 69         } else {
 70                 if (sbi->free_clusters != -1)
 71                         fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
 72                 if (sbi->prev_free != -1)
 73                         fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
 74                 mark_buffer_dirty(bh);
 75         }
 76         brelse(bh);
 77 
 78         return 0;
 79 }
 80 
 81 /*
 82  * fat_chain_add() adds a new cluster to the chain of clusters represented
 83  * by inode.
 84  */
 85 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
 86 {
 87         struct super_block *sb = inode->i_sb;
 88         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 89         int ret, new_fclus, last;
 90 
 91         /*
 92          * We must locate the last cluster of the file to add this new
 93          * one (new_dclus) to the end of the link list (the FAT).
 94          */
 95         last = new_fclus = 0;
 96         if (MSDOS_I(inode)->i_start) {
 97                 int fclus, dclus;
 98 
 99                 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
100                 if (ret < 0)
101                         return ret;
102                 new_fclus = fclus + 1;
103                 last = dclus;
104         }
105 
106         /* add new one to the last of the cluster chain */
107         if (last) {
108                 struct fat_entry fatent;
109 
110                 fatent_init(&fatent);
111                 ret = fat_ent_read(inode, &fatent, last);
112                 if (ret >= 0) {
113                         int wait = inode_needs_sync(inode);
114                         ret = fat_ent_write(inode, &fatent, new_dclus, wait);
115                         fatent_brelse(&fatent);
116                 }
117                 if (ret < 0)
118                         return ret;
119 //              fat_cache_add(inode, new_fclus, new_dclus);
120         } else {
121                 MSDOS_I(inode)->i_start = new_dclus;
122                 MSDOS_I(inode)->i_logstart = new_dclus;
123                 /*
124                  * Since generic_write_sync() synchronizes regular files later,
125                  * we sync here only directories.
126                  */
127                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
128                         ret = fat_sync_inode(inode);
129                         if (ret)
130                                 return ret;
131                 } else
132                         mark_inode_dirty(inode);
133         }
134         if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
135                 fat_fs_error(sb, "clusters badly computed (%d != %llu)",
136                              new_fclus,
137                              (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
138                 fat_cache_inval_inode(inode);
139         }
140         inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
141 
142         return 0;
143 }
144 
145 extern struct timezone sys_tz;
146 
147 /*
148  * The epoch of FAT timestamp is 1980.
149  *     :  bits :     value
150  * date:  0 -  4: day   (1 -  31)
151  * date:  5 -  8: month (1 -  12)
152  * date:  9 - 15: year  (0 - 127) from 1980
153  * time:  0 -  4: sec   (0 -  29) 2sec counts
154  * time:  5 - 10: min   (0 -  59)
155  * time: 11 - 15: hour  (0 -  23)
156  */
157 #define SECS_PER_MIN    60
158 #define SECS_PER_HOUR   (60 * 60)
159 #define SECS_PER_DAY    (SECS_PER_HOUR * 24)
160 #define UNIX_SECS_1980  315532800L
161 #if BITS_PER_LONG == 64
162 #define UNIX_SECS_2108  4354819200L
163 #endif
164 /* days between 1.1.70 and 1.1.80 (2 leap days) */
165 #define DAYS_DELTA      (365 * 10 + 2)
166 /* 120 (2100 - 1980) isn't leap year */
167 #define YEAR_2100       120
168 #define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
169 
170 /* Linear day numbers of the respective 1sts in non-leap years. */
171 static time_t days_in_year[] = {
172         /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
173         0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
174 };
175 
176 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
177 void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
178                        __le16 __time, __le16 __date, u8 time_cs)
179 {
180         u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
181         time_t second, day, leap_day, month, year;
182 
183         year  = date >> 9;
184         month = max(1, (date >> 5) & 0xf);
185         day   = max(1, date & 0x1f) - 1;
186 
187         leap_day = (year + 3) / 4;
188         if (year > YEAR_2100)           /* 2100 isn't leap year */
189                 leap_day--;
190         if (IS_LEAP_YEAR(year) && month > 2)
191                 leap_day++;
192 
193         second =  (time & 0x1f) << 1;
194         second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
195         second += (time >> 11) * SECS_PER_HOUR;
196         second += (year * 365 + leap_day
197                    + days_in_year[month] + day
198                    + DAYS_DELTA) * SECS_PER_DAY;
199 
200         if (!sbi->options.tz_utc)
201                 second += sys_tz.tz_minuteswest * SECS_PER_MIN;
202 
203         if (time_cs) {
204                 ts->tv_sec = second + (time_cs / 100);
205                 ts->tv_nsec = (time_cs % 100) * 10000000;
206         } else {
207                 ts->tv_sec = second;
208                 ts->tv_nsec = 0;
209         }
210 }
211 
212 /* Convert linear UNIX date to a FAT time/date pair. */
213 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
214                        __le16 *time, __le16 *date, u8 *time_cs)
215 {
216         time_t second = ts->tv_sec;
217         time_t day, leap_day, month, year;
218 
219         if (!sbi->options.tz_utc)
220                 second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
221 
222         /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
223         if (second < UNIX_SECS_1980) {
224                 *time = 0;
225                 *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
226                 if (time_cs)
227                         *time_cs = 0;
228                 return;
229         }
230 #if BITS_PER_LONG == 64
231         if (second >= UNIX_SECS_2108) {
232                 *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
233                 *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
234                 if (time_cs)
235                         *time_cs = 199;
236                 return;
237         }
238 #endif
239 
240         day = second / SECS_PER_DAY - DAYS_DELTA;
241         year = day / 365;
242         leap_day = (year + 3) / 4;
243         if (year > YEAR_2100)           /* 2100 isn't leap year */
244                 leap_day--;
245         if (year * 365 + leap_day > day)
246                 year--;
247         leap_day = (year + 3) / 4;
248         if (year > YEAR_2100)           /* 2100 isn't leap year */
249                 leap_day--;
250         day -= year * 365 + leap_day;
251 
252         if (IS_LEAP_YEAR(year) && day == days_in_year[3]) {
253                 month = 2;
254         } else {
255                 if (IS_LEAP_YEAR(year) && day > days_in_year[3])
256                         day--;
257                 for (month = 1; month < 12; month++) {
258                         if (days_in_year[month + 1] > day)
259                                 break;
260                 }
261         }
262         day -= days_in_year[month];
263 
264         *time = cpu_to_le16(((second / SECS_PER_HOUR) % 24) << 11
265                             | ((second / SECS_PER_MIN) % 60) << 5
266                             | (second % SECS_PER_MIN) >> 1);
267         *date = cpu_to_le16((year << 9) | (month << 5) | (day + 1));
268         if (time_cs)
269                 *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
270 }
271 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
272 
273 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
274 {
275         int i, err = 0;
276 
277         ll_rw_block(SWRITE, nr_bhs, bhs);
278         for (i = 0; i < nr_bhs; i++) {
279                 wait_on_buffer(bhs[i]);
280                 if (buffer_eopnotsupp(bhs[i])) {
281                         clear_buffer_eopnotsupp(bhs[i]);
282                         err = -EOPNOTSUPP;
283                 } else if (!err && !buffer_uptodate(bhs[i]))
284                         err = -EIO;
285         }
286         return err;
287 }
288 
289 

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