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 #include <linux/iversion.h>
  11
  12 /*
  13  * fat_fs_error reports a file system problem that might indicate fa data
  14  * corruption/inconsistency. Depending on 'errors' mount option the
  15  * panic() is called, or error message is printed FAT and nothing is done,
  16  * or filesystem is remounted read-only (default behavior).
  17  * In case the file system is remounted read-only, it can be made writable
  18  * again by remounting it.
  19  */
  20 void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
  21 {
  22         struct fat_mount_options *opts = &MSDOS_SB(sb)->options;
  23         va_list args;
  24         struct va_format vaf;
  25
  26         if (report) {
  27                 va_start(args, fmt);
  28                 vaf.fmt = fmt;
  29                 vaf.va = &args;
  30                 fat_msg(sb, KERN_ERR, "error, %pV", &vaf);
  31                 va_end(args);
  32         }
  33
  34         if (opts->errors == FAT_ERRORS_PANIC)
  35                 panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);
  36         else if (opts->errors == FAT_ERRORS_RO && !sb_rdonly(sb)) {
  37                 sb->s_flags |= SB_RDONLY;
  38                 fat_msg(sb, KERN_ERR, "Filesystem has been set read-only");
  39         }
  40 }
  41 EXPORT_SYMBOL_GPL(__fat_fs_error);
  42
  43 /**
  44  * fat_msg() - print preformated FAT specific messages. Every thing what is
  45  * not fat_fs_error() should be fat_msg().
  46  */
  47 void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
  48 {
  49         struct va_format vaf;
  50         va_list args;
  51
  52         va_start(args, fmt);
  53         vaf.fmt = fmt;
  54         vaf.va = &args;
  55         printk("%sFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
  56         va_end(args);
  57 }
  58
  59 /* Flushes the number of free clusters on FAT32 */
  60 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
  61 int fat_clusters_flush(struct super_block *sb)
  62 {
  63         struct msdos_sb_info *sbi = MSDOS_SB(sb);
  64         struct buffer_head *bh;
  65         struct fat_boot_fsinfo *fsinfo;
  66
  67         if (!is_fat32(sbi))
  68                 return 0;
  69
  70         bh = sb_bread(sb, sbi->fsinfo_sector);
  71         if (bh == NULL) {
  72                 fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
  73                 return -EIO;
  74         }
  75
  76         fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
  77         /* Sanity check */
  78         if (!IS_FSINFO(fsinfo)) {
  79                 fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
  80                        "0x%08x, 0x%08x (sector = %lu)",
  81                        le32_to_cpu(fsinfo->signature1),
  82                        le32_to_cpu(fsinfo->signature2),
  83                        sbi->fsinfo_sector);
  84         } else {
  85                 if (sbi->free_clusters != -1)
  86                         fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
  87                 if (sbi->prev_free != -1)
  88                         fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
  89                 mark_buffer_dirty(bh);
  90         }
  91         brelse(bh);
  92
  93         return 0;
  94 }
  95
  96 /*
  97  * fat_chain_add() adds a new cluster to the chain of clusters represented
  98  * by inode.
  99  */
 100 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
 101 {
 102         struct super_block *sb = inode->i_sb;
 103         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 104         int ret, new_fclus, last;
 105
 106         /*
 107          * We must locate the last cluster of the file to add this new
 108          * one (new_dclus) to the end of the link list (the FAT).
 109          */
 110         last = new_fclus = 0;
 111         if (MSDOS_I(inode)->i_start) {
 112                 int fclus, dclus;
 113
 114                 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 115                 if (ret < 0)
 116                         return ret;
 117                 new_fclus = fclus + 1;
 118                 last = dclus;
 119         }
 120
 121         /* add new one to the last of the cluster chain */
 122         if (last) {
 123                 struct fat_entry fatent;
 124
 125                 fatent_init(&fatent);
 126                 ret = fat_ent_read(inode, &fatent, last);
 127                 if (ret >= 0) {
 128                         int wait = inode_needs_sync(inode);
 129                         ret = fat_ent_write(inode, &fatent, new_dclus, wait);
 130                         fatent_brelse(&fatent);
 131                 }
 132                 if (ret < 0)
 133                         return ret;
 134                 /*
 135                  * FIXME:Although we can add this cache, fat_cache_add() is
 136                  * assuming to be called after linear search with fat_cache_id.
 137                  */
 138 //              fat_cache_add(inode, new_fclus, new_dclus);
 139         } else {
 140                 MSDOS_I(inode)->i_start = new_dclus;
 141                 MSDOS_I(inode)->i_logstart = new_dclus;
 142                 /*
 143                  * Since generic_write_sync() synchronizes regular files later,
 144                  * we sync here only directories.
 145                  */
 146                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
 147                         ret = fat_sync_inode(inode);
 148                         if (ret)
 149                                 return ret;
 150                 } else
 151                         mark_inode_dirty(inode);
 152         }
 153         if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
 154                 fat_fs_error(sb, "clusters badly computed (%d != %llu)",
 155                              new_fclus,
 156                              (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
 157                 fat_cache_inval_inode(inode);
 158         }
 159         inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
 160
 161         return 0;
 162 }
 163
 164 /*
 165  * The epoch of FAT timestamp is 1980.
 166  *     :  bits :     value
 167  * date:  0 -  4: day   (1 -  31)
 168  * date:  5 -  8: month (1 -  12)
 169  * date:  9 - 15: year  (0 - 127) from 1980
 170  * time:  0 -  4: sec   (0 -  29) 2sec counts
 171  * time:  5 - 10: min   (0 -  59)
 172  * time: 11 - 15: hour  (0 -  23)
 173  */
 174 #define SECS_PER_MIN    60
 175 #define SECS_PER_HOUR   (60 * 60)
 176 #define SECS_PER_DAY    (SECS_PER_HOUR * 24)
 177 /* days between 1.1.70 and 1.1.80 (2 leap days) */
 178 #define DAYS_DELTA      (365 * 10 + 2)
 179 /* 120 (2100 - 1980) isn't leap year */
 180 #define YEAR_2100       120
 181 #define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
 182
 183 /* Linear day numbers of the respective 1sts in non-leap years. */
 184 static long days_in_year[] = {
 185         /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
 186         0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 187 };
 188
 189 static inline int fat_tz_offset(struct msdos_sb_info *sbi)
 190 {
 191         return (sbi->options.tz_set ?
 192                -sbi->options.time_offset :
 193                sys_tz.tz_minuteswest) * SECS_PER_MIN;
 194 }
 195
 196 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 197 void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 198                        __le16 __time, __le16 __date, u8 time_cs)
 199 {
 200         u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
 201         time64_t second;
 202         long day, leap_day, month, year;
 203
 204         year  = date >> 9;
 205         month = max(1, (date >> 5) & 0xf);
 206         day   = max(1, date & 0x1f) - 1;
 207
 208         leap_day = (year + 3) / 4;
 209         if (year > YEAR_2100)           /* 2100 isn't leap year */
 210                 leap_day--;
 211         if (IS_LEAP_YEAR(year) && month > 2)
 212                 leap_day++;
 213
 214         second =  (time & 0x1f) << 1;
 215         second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
 216         second += (time >> 11) * SECS_PER_HOUR;
 217         second += (time64_t)(year * 365 + leap_day
 218                    + days_in_year[month] + day
 219                    + DAYS_DELTA) * SECS_PER_DAY;
 220
 221         second += fat_tz_offset(sbi);
 222
 223         if (time_cs) {
 224                 ts->tv_sec = second + (time_cs / 100);
 225                 ts->tv_nsec = (time_cs % 100) * 10000000;
 226         } else {
 227                 ts->tv_sec = second;
 228                 ts->tv_nsec = 0;
 229         }
 230 }
 231
 232 /* Convert linear UNIX date to a FAT time/date pair. */
 233 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 234                        __le16 *time, __le16 *date, u8 *time_cs)
 235 {
 236         struct tm tm;
 237         time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &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 static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
 270 {
 271         return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
 272 }
 273 /*
 274  * truncate the various times with appropriate granularity:
 275  *   root inode:
 276  *     all times always 0
 277  *   all other inodes:
 278  *     mtime - 2 seconds
 279  *     ctime
 280  *       msdos - 2 seconds
 281  *       vfat  - 10 milliseconds
 282  *     atime - 24 hours (00:00:00 in local timezone)
 283  */
 284 int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
 285 {
 286         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 287         struct timespec64 ts;
 288
 289         if (inode->i_ino == MSDOS_ROOT_INO)
 290                 return 0;
 291
 292         if (now == NULL) {
 293                 now = &ts;
 294                 ts = current_time(inode);
 295         }
 296
 297         if (flags & S_ATIME) {
 298                 /* to localtime */
 299                 time64_t seconds = now->tv_sec - fat_tz_offset(sbi);
 300                 s32 remainder;
 301
 302                 div_s64_rem(seconds, SECS_PER_DAY, &remainder);
 303                 /* to day boundary, and back to unix time */
 304                 seconds = seconds + fat_tz_offset(sbi) - remainder;
 305
 306                 inode->i_atime = (struct timespec64){ seconds, 0 };
 307         }
 308         if (flags & S_CTIME) {
 309                 if (sbi->options.isvfat)
 310                         inode->i_ctime = timespec64_trunc(*now, 10000000);
 311                 else
 312                         inode->i_ctime = fat_timespec64_trunc_2secs(*now);
 313         }
 314         if (flags & S_MTIME)
 315                 inode->i_mtime = fat_timespec64_trunc_2secs(*now);
 316
 317         return 0;
 318 }
 319 EXPORT_SYMBOL_GPL(fat_truncate_time);
 320
 321 int fat_update_time(struct inode *inode, struct timespec64 *now, int flags)
 322 {
 323         int iflags = I_DIRTY_TIME;
 324         bool dirty = false;
 325
 326         if (inode->i_ino == MSDOS_ROOT_INO)
 327                 return 0;
 328
 329         fat_truncate_time(inode, now, flags);
 330         if (flags & S_VERSION)
 331                 dirty = inode_maybe_inc_iversion(inode, false);
 332         if ((flags & (S_ATIME | S_CTIME | S_MTIME)) &&
 333             !(inode->i_sb->s_flags & SB_LAZYTIME))
 334                 dirty = true;
 335
 336         if (dirty)
 337                 iflags |= I_DIRTY_SYNC;
 338         __mark_inode_dirty(inode, iflags);
 339         return 0;
 340 }
 341 EXPORT_SYMBOL_GPL(fat_update_time);
 342
 343 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 344 {
 345         int i, err = 0;
 346
 347         for (i = 0; i < nr_bhs; i++)
 348                 write_dirty_buffer(bhs[i], 0);
 349
 350         for (i = 0; i < nr_bhs; i++) {
 351                 wait_on_buffer(bhs[i]);
 352                 if (!err && !buffer_uptodate(bhs[i]))
 353                         err = -EIO;
 354         }
 355         return err;
 356 }