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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 "fat.h"
 10 
 11 /*
 12  * fat_fs_error reports a file system problem that might indicate fa data
 13  * corruption/inconsistency. Depending on 'errors' mount option the
 14  * panic() is called, or error message is printed FAT and nothing is done,
 15  * or filesystem is remounted read-only (default behavior).
 16  * In case the file system is remounted read-only, it can be made writable
 17  * again by remounting it.
 18  */
 19 void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
 20 {
 21         struct fat_mount_options *opts = &MSDOS_SB(sb)->options;
 22         va_list args;
 23         struct va_format vaf;
 24 
 25         if (report) {
 26                 va_start(args, fmt);
 27                 vaf.fmt = fmt;
 28                 vaf.va = &args;
 29                 fat_msg(sb, KERN_ERR, "error, %pV", &vaf);
 30                 va_end(args);
 31         }
 32 
 33         if (opts->errors == FAT_ERRORS_PANIC)
 34                 panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);
 35         else if (opts->errors == FAT_ERRORS_RO && !(sb->s_flags & MS_RDONLY)) {
 36                 sb->s_flags |= MS_RDONLY;
 37                 fat_msg(sb, KERN_ERR, "Filesystem has been set read-only");
 38         }
 39 }
 40 EXPORT_SYMBOL_GPL(__fat_fs_error);
 41 
 42 /**
 43  * fat_msg() - print preformated FAT specific messages. Every thing what is
 44  * not fat_fs_error() should be fat_msg().
 45  */
 46 void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
 47 {
 48         struct va_format vaf;
 49         va_list args;
 50 
 51         va_start(args, fmt);
 52         vaf.fmt = fmt;
 53         vaf.va = &args;
 54         printk("%sFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
 55         va_end(args);
 56 }
 57 
 58 /* Flushes the number of free clusters on FAT32 */
 59 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
 60 int fat_clusters_flush(struct super_block *sb)
 61 {
 62         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 63         struct buffer_head *bh;
 64         struct fat_boot_fsinfo *fsinfo;
 65 
 66         if (sbi->fat_bits != 32)
 67                 return 0;
 68 
 69         bh = sb_bread(sb, sbi->fsinfo_sector);
 70         if (bh == NULL) {
 71                 fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
 72                 return -EIO;
 73         }
 74 
 75         fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
 76         /* Sanity check */
 77         if (!IS_FSINFO(fsinfo)) {
 78                 fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
 79                        "0x%08x, 0x%08x (sector = %lu)",
 80                        le32_to_cpu(fsinfo->signature1),
 81                        le32_to_cpu(fsinfo->signature2),
 82                        sbi->fsinfo_sector);
 83         } else {
 84                 if (sbi->free_clusters != -1)
 85                         fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
 86                 if (sbi->prev_free != -1)
 87                         fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
 88                 mark_buffer_dirty(bh);
 89         }
 90         brelse(bh);
 91 
 92         return 0;
 93 }
 94 
 95 /*
 96  * fat_chain_add() adds a new cluster to the chain of clusters represented
 97  * by inode.
 98  */
 99 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
100 {
101         struct super_block *sb = inode->i_sb;
102         struct msdos_sb_info *sbi = MSDOS_SB(sb);
103         int ret, new_fclus, last;
104 
105         /*
106          * We must locate the last cluster of the file to add this new
107          * one (new_dclus) to the end of the link list (the FAT).
108          */
109         last = new_fclus = 0;
110         if (MSDOS_I(inode)->i_start) {
111                 int fclus, dclus;
112 
113                 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
114                 if (ret < 0)
115                         return ret;
116                 new_fclus = fclus + 1;
117                 last = dclus;
118         }
119 
120         /* add new one to the last of the cluster chain */
121         if (last) {
122                 struct fat_entry fatent;
123 
124                 fatent_init(&fatent);
125                 ret = fat_ent_read(inode, &fatent, last);
126                 if (ret >= 0) {
127                         int wait = inode_needs_sync(inode);
128                         ret = fat_ent_write(inode, &fatent, new_dclus, wait);
129                         fatent_brelse(&fatent);
130                 }
131                 if (ret < 0)
132                         return ret;
133                 /*
134                  * FIXME:Although we can add this cache, fat_cache_add() is
135                  * assuming to be called after linear search with fat_cache_id.
136                  */
137 //              fat_cache_add(inode, new_fclus, new_dclus);
138         } else {
139                 MSDOS_I(inode)->i_start = new_dclus;
140                 MSDOS_I(inode)->i_logstart = new_dclus;
141                 /*
142                  * Since generic_write_sync() synchronizes regular files later,
143                  * we sync here only directories.
144                  */
145                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
146                         ret = fat_sync_inode(inode);
147                         if (ret)
148                                 return ret;
149                 } else
150                         mark_inode_dirty(inode);
151         }
152         if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
153                 fat_fs_error(sb, "clusters badly computed (%d != %llu)",
154                              new_fclus,
155                              (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
156                 fat_cache_inval_inode(inode);
157         }
158         inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
159 
160         return 0;
161 }
162 
163 /*
164  * The epoch of FAT timestamp is 1980.
165  *     :  bits :     value
166  * date:  0 -  4: day   (1 -  31)
167  * date:  5 -  8: month (1 -  12)
168  * date:  9 - 15: year  (0 - 127) from 1980
169  * time:  0 -  4: sec   (0 -  29) 2sec counts
170  * time:  5 - 10: min   (0 -  59)
171  * time: 11 - 15: hour  (0 -  23)
172  */
173 #define SECS_PER_MIN    60
174 #define SECS_PER_HOUR   (60 * 60)
175 #define SECS_PER_DAY    (SECS_PER_HOUR * 24)
176 /* days between 1.1.70 and 1.1.80 (2 leap days) */
177 #define DAYS_DELTA      (365 * 10 + 2)
178 /* 120 (2100 - 1980) isn't leap year */
179 #define YEAR_2100       120
180 #define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
181 
182 /* Linear day numbers of the respective 1sts in non-leap years. */
183 static time_t days_in_year[] = {
184         /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
185         0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
186 };
187 
188 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
189 void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
190                        __le16 __time, __le16 __date, u8 time_cs)
191 {
192         u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
193         time_t second, day, leap_day, month, year;
194 
195         year  = date >> 9;
196         month = max(1, (date >> 5) & 0xf);
197         day   = max(1, date & 0x1f) - 1;
198 
199         leap_day = (year + 3) / 4;
200         if (year > YEAR_2100)           /* 2100 isn't leap year */
201                 leap_day--;
202         if (IS_LEAP_YEAR(year) && month > 2)
203                 leap_day++;
204 
205         second =  (time & 0x1f) << 1;
206         second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
207         second += (time >> 11) * SECS_PER_HOUR;
208         second += (year * 365 + leap_day
209                    + days_in_year[month] + day
210                    + DAYS_DELTA) * SECS_PER_DAY;
211 
212         if (!sbi->options.tz_set)
213                 second += sys_tz.tz_minuteswest * SECS_PER_MIN;
214         else
215                 second -= sbi->options.time_offset * SECS_PER_MIN;
216 
217         if (time_cs) {
218                 ts->tv_sec = second + (time_cs / 100);
219                 ts->tv_nsec = (time_cs % 100) * 10000000;
220         } else {
221                 ts->tv_sec = second;
222                 ts->tv_nsec = 0;
223         }
224 }
225 
226 /* Convert linear UNIX date to a FAT time/date pair. */
227 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
228                        __le16 *time, __le16 *date, u8 *time_cs)
229 {
230         struct tm tm;
231         time_to_tm(ts->tv_sec,
232                    (sbi->options.tz_set ? sbi->options.time_offset :
233                    -sys_tz.tz_minuteswest) * SECS_PER_MIN, &tm);
234 
235         /*  FAT can only support year between 1980 to 2107 */
236         if (tm.tm_year < 1980 - 1900) {
237                 *time = 0;
238                 *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
239                 if (time_cs)
240                         *time_cs = 0;
241                 return;
242         }
243         if (tm.tm_year > 2107 - 1900) {
244                 *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
245                 *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
246                 if (time_cs)
247                         *time_cs = 199;
248                 return;
249         }
250 
251         /* from 1900 -> from 1980 */
252         tm.tm_year -= 80;
253         /* 0~11 -> 1~12 */
254         tm.tm_mon++;
255         /* 0~59 -> 0~29(2sec counts) */
256         tm.tm_sec >>= 1;
257 
258         *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
259         *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
260         if (time_cs)
261                 *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
262 }
263 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
264 
265 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
266 {
267         int i, err = 0;
268 
269         for (i = 0; i < nr_bhs; i++)
270                 write_dirty_buffer(bhs[i], 0);
271 
272         for (i = 0; i < nr_bhs; i++) {
273                 wait_on_buffer(bhs[i]);
274                 if (!err && !buffer_uptodate(bhs[i]))
275                         err = -EIO;
276         }
277         return err;
278 }
279 

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