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 *sb, int report, const char *fmt, ...)
  24 {
  25         struct fat_mount_options *opts = &MSDOS_SB(sb)->options;
  26         va_list args;
  27         struct va_format vaf;
  28
  29         if (report) {
  30                 va_start(args, fmt);
  31                 vaf.fmt = fmt;
  32                 vaf.va = &args;
  33                 fat_msg(sb, KERN_ERR, "error, %pV", &vaf);
  34                 va_end(args);
  35         }
  36
  37         if (opts->errors == FAT_ERRORS_PANIC)
  38                 panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);
  39         else if (opts->errors == FAT_ERRORS_RO && !(sb->s_flags & MS_RDONLY)) {
  40                 sb->s_flags |= MS_RDONLY;
  41                 fat_msg(sb, KERN_ERR, "Filesystem has been set read-only");
  42         }
  43 }
  44 EXPORT_SYMBOL_GPL(__fat_fs_error);
  45
  46 /**
  47  * fat_msg() - print preformated FAT specific messages. Every thing what is
  48  * not fat_fs_error() should be fat_msg().
  49  */
  50 void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
  51 {
  52         struct va_format vaf;
  53         va_list args;
  54
  55         va_start(args, fmt);
  56         vaf.fmt = fmt;
  57         vaf.va = &args;
  58         printk("%sFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
  59         va_end(args);
  60 }
  61
  62 /* Flushes the number of free clusters on FAT32 */
  63 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
  64 int fat_clusters_flush(struct super_block *sb)
  65 {
  66         struct msdos_sb_info *sbi = MSDOS_SB(sb);
  67         struct buffer_head *bh;
  68         struct fat_boot_fsinfo *fsinfo;
  69
  70         if (sbi->fat_bits != 32)
  71                 return 0;
  72
  73         bh = sb_bread(sb, sbi->fsinfo_sector);
  74         if (bh == NULL) {
  75                 fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
  76                 return -EIO;
  77         }
  78
  79         fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
  80         /* Sanity check */
  81         if (!IS_FSINFO(fsinfo)) {
  82                 fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
  83                        "0x%08x, 0x%08x (sector = %lu)",
  84                        le32_to_cpu(fsinfo->signature1),
  85                        le32_to_cpu(fsinfo->signature2),
  86                        sbi->fsinfo_sector);
  87         } else {
  88                 if (sbi->free_clusters != -1)
  89                         fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
  90                 if (sbi->prev_free != -1)
  91                         fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
  92                 mark_buffer_dirty(bh);
  93         }
  94         brelse(bh);
  95
  96         return 0;
  97 }
  98
  99 /*
 100  * fat_chain_add() adds a new cluster to the chain of clusters represented
 101  * by inode.
 102  */
 103 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
 104 {
 105         struct super_block *sb = inode->i_sb;
 106         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 107         int ret, new_fclus, last;
 108
 109         /*
 110          * We must locate the last cluster of the file to add this new
 111          * one (new_dclus) to the end of the link list (the FAT).
 112          */
 113         last = new_fclus = 0;
 114         if (MSDOS_I(inode)->i_start) {
 115                 int fclus, dclus;
 116
 117                 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 118                 if (ret < 0)
 119                         return ret;
 120                 new_fclus = fclus + 1;
 121                 last = dclus;
 122         }
 123
 124         /* add new one to the last of the cluster chain */
 125         if (last) {
 126                 struct fat_entry fatent;
 127
 128                 fatent_init(&fatent);
 129                 ret = fat_ent_read(inode, &fatent, last);
 130                 if (ret >= 0) {
 131                         int wait = inode_needs_sync(inode);
 132                         ret = fat_ent_write(inode, &fatent, new_dclus, wait);
 133                         fatent_brelse(&fatent);
 134                 }
 135                 if (ret < 0)
 136                         return ret;
 137                 /*
 138                  * FIXME:Although we can add this cache, fat_cache_add() is
 139                  * assuming to be called after linear search with fat_cache_id.
 140                  */
 141 //              fat_cache_add(inode, new_fclus, new_dclus);
 142         } else {
 143                 MSDOS_I(inode)->i_start = new_dclus;
 144                 MSDOS_I(inode)->i_logstart = new_dclus;
 145                 /*
 146                  * Since generic_write_sync() synchronizes regular files later,
 147                  * we sync here only directories.
 148                  */
 149                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
 150                         ret = fat_sync_inode(inode);
 151                         if (ret)
 152                                 return ret;
 153                 } else
 154                         mark_inode_dirty(inode);
 155         }
 156         if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
 157                 fat_fs_error(sb, "clusters badly computed (%d != %llu)",
 158                              new_fclus,
 159                              (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
 160                 fat_cache_inval_inode(inode);
 161         }
 162         inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
 163
 164         return 0;
 165 }
 166
 167 /*
 168  * The epoch of FAT timestamp is 1980.
 169  *     :  bits :     value
 170  * date:  0 -  4: day   (1 -  31)
 171  * date:  5 -  8: month (1 -  12)
 172  * date:  9 - 15: year  (0 - 127) from 1980
 173  * time:  0 -  4: sec   (0 -  29) 2sec counts
 174  * time:  5 - 10: min   (0 -  59)
 175  * time: 11 - 15: hour  (0 -  23)
 176  */
 177 #define SECS_PER_MIN    60
 178 #define SECS_PER_HOUR   (60 * 60)
 179 #define SECS_PER_DAY    (SECS_PER_HOUR * 24)
 180 /* days between 1.1.70 and 1.1.80 (2 leap days) */
 181 #define DAYS_DELTA      (365 * 10 + 2)
 182 /* 120 (2100 - 1980) isn't leap year */
 183 #define YEAR_2100       120
 184 #define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
 185
 186 /* Linear day numbers of the respective 1sts in non-leap years. */
 187 static time_t days_in_year[] = {
 188         /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
 189         0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 190 };
 191
 192 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 193 void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
 194                        __le16 __time, __le16 __date, u8 time_cs)
 195 {
 196         u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
 197         time_t second, day, leap_day, month, year;
 198
 199         year  = date >> 9;
 200         month = max(1, (date >> 5) & 0xf);
 201         day   = max(1, date & 0x1f) - 1;
 202
 203         leap_day = (year + 3) / 4;
 204         if (year > YEAR_2100)           /* 2100 isn't leap year */
 205                 leap_day--;
 206         if (IS_LEAP_YEAR(year) && month > 2)
 207                 leap_day++;
 208
 209         second =  (time & 0x1f) << 1;
 210         second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
 211         second += (time >> 11) * SECS_PER_HOUR;
 212         second += (year * 365 + leap_day
 213                    + days_in_year[month] + day
 214                    + DAYS_DELTA) * SECS_PER_DAY;
 215
 216         if (!sbi->options.tz_set)
 217                 second += sys_tz.tz_minuteswest * SECS_PER_MIN;
 218         else
 219                 second -= sbi->options.time_offset * SECS_PER_MIN;
 220
 221         if (time_cs) {
 222                 ts->tv_sec = second + (time_cs / 100);
 223                 ts->tv_nsec = (time_cs % 100) * 10000000;
 224         } else {
 225                 ts->tv_sec = second;
 226                 ts->tv_nsec = 0;
 227         }
 228 }
 229
 230 /* Convert linear UNIX date to a FAT time/date pair. */
 231 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
 232                        __le16 *time, __le16 *date, u8 *time_cs)
 233 {
 234         struct tm tm;
 235         time_to_tm(ts->tv_sec,
 236                    (sbi->options.tz_set ? sbi->options.time_offset :
 237                    -sys_tz.tz_minuteswest) * SECS_PER_MIN, &tm);
 238
 239         /*  FAT can only support year between 1980 to 2107 */
 240         if (tm.tm_year < 1980 - 1900) {
 241                 *time = 0;
 242                 *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
 243                 if (time_cs)
 244                         *time_cs = 0;
 245                 return;
 246         }
 247         if (tm.tm_year > 2107 - 1900) {
 248                 *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
 249                 *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
 250                 if (time_cs)
 251                         *time_cs = 199;
 252                 return;
 253         }
 254
 255         /* from 1900 -> from 1980 */
 256         tm.tm_year -= 80;
 257         /* 0~11 -> 1~12 */
 258         tm.tm_mon++;
 259         /* 0~59 -> 0~29(2sec counts) */
 260         tm.tm_sec >>= 1;
 261
 262         *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
 263         *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
 264         if (time_cs)
 265                 *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
 266 }
 267 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 268
 269 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 270 {
 271         int i, err = 0;
 272
 273         for (i = 0; i < nr_bhs; i++)
 274                 write_dirty_buffer(bhs[i], WRITE);
 275
 276         for (i = 0; i < nr_bhs; i++) {
 277                 wait_on_buffer(bhs[i]);
 278                 if (!err && !buffer_uptodate(bhs[i]))
 279                         err = -EIO;
 280         }
 281         return err;
 282 }