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 "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_rdonly(sb)) {
  36                 sb->s_flags |= SB_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 long 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 timespec64 *ts,
 190                        __le16 __time, __le16 __date, u8 time_cs)
 191 {
 192         u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
 193         time64_t second;
 194         long day, leap_day, month, year;
 195
 196         year  = date >> 9;
 197         month = max(1, (date >> 5) & 0xf);
 198         day   = max(1, date & 0x1f) - 1;
 199
 200         leap_day = (year + 3) / 4;
 201         if (year > YEAR_2100)           /* 2100 isn't leap year */
 202                 leap_day--;
 203         if (IS_LEAP_YEAR(year) && month > 2)
 204                 leap_day++;
 205
 206         second =  (time & 0x1f) << 1;
 207         second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
 208         second += (time >> 11) * SECS_PER_HOUR;
 209         second += (time64_t)(year * 365 + leap_day
 210                    + days_in_year[month] + day
 211                    + DAYS_DELTA) * SECS_PER_DAY;
 212
 213         if (!sbi->options.tz_set)
 214                 second += sys_tz.tz_minuteswest * SECS_PER_MIN;
 215         else
 216                 second -= sbi->options.time_offset * SECS_PER_MIN;
 217
 218         if (time_cs) {
 219                 ts->tv_sec = second + (time_cs / 100);
 220                 ts->tv_nsec = (time_cs % 100) * 10000000;
 221         } else {
 222                 ts->tv_sec = second;
 223                 ts->tv_nsec = 0;
 224         }
 225 }
 226
 227 /* Convert linear UNIX date to a FAT time/date pair. */
 228 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 229                        __le16 *time, __le16 *date, u8 *time_cs)
 230 {
 231         struct tm tm;
 232         time64_to_tm(ts->tv_sec,
 233                    (sbi->options.tz_set ? sbi->options.time_offset :
 234                    -sys_tz.tz_minuteswest) * SECS_PER_MIN, &tm);
 235
 236         /*  FAT can only support year between 1980 to 2107 */
 237         if (tm.tm_year < 1980 - 1900) {
 238                 *time = 0;
 239                 *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
 240                 if (time_cs)
 241                         *time_cs = 0;
 242                 return;
 243         }
 244         if (tm.tm_year > 2107 - 1900) {
 245                 *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
 246                 *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
 247                 if (time_cs)
 248                         *time_cs = 199;
 249                 return;
 250         }
 251
 252         /* from 1900 -> from 1980 */
 253         tm.tm_year -= 80;
 254         /* 0~11 -> 1~12 */
 255         tm.tm_mon++;
 256         /* 0~59 -> 0~29(2sec counts) */
 257         tm.tm_sec >>= 1;
 258
 259         *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
 260         *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
 261         if (time_cs)
 262                 *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
 263 }
 264 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 265
 266 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 267 {
 268         int i, err = 0;
 269
 270         for (i = 0; i < nr_bhs; i++)
 271                 write_dirty_buffer(bhs[i], 0);
 272
 273         for (i = 0; i < nr_bhs; i++) {
 274                 wait_on_buffer(bhs[i]);
 275                 if (!err && !buffer_uptodate(bhs[i]))
 276                         err = -EIO;
 277         }
 278         return err;
 279 }