fs/fat/misc.c

   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