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