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/genhd.h>
  13 #include "fat.h"
  14
  15 /* Copied from block/gendisk.c */
  16 static void set_disk_ro_uevent(struct gendisk *gd, int ro)
  17 {
  18         char event[] = "DISK_RO=1";
  19         char *envp[] = { event, NULL };
  20
  21         if (!ro)
  22                 event[8] = '0';
  23         kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
  24 }
  25
  26 /*
  27  * fat_fs_error reports a file system problem that might indicate fa data
  28  * corruption/inconsistency. Depending on 'errors' mount option the
  29  * panic() is called, or error message is printed FAT and nothing is done,
  30  * or filesystem is remounted read-only (default behavior).
  31  * In case the file system is remounted read-only, it can be made writable
  32  * again by remounting it.
  33  */
  34 void fat_fs_error(struct super_block *s, const char *fmt, ...)
  35 {
  36         struct fat_mount_options *opts = &MSDOS_SB(s)->options;
  37         va_list args;
  38
  39         printk(KERN_ERR "FAT: Filesystem error (dev %s)\n", s->s_id);
  40
  41         printk(KERN_ERR "    ");
  42         va_start(args, fmt);
  43         vprintk(fmt, args);
  44         va_end(args);
  45         printk("\n");
  46
  47         if (opts->errors == FAT_ERRORS_PANIC)
  48                 panic("    FAT fs panic from previous error\n");
  49         else if (opts->errors == FAT_ERRORS_RO && !(s->s_flags & MS_RDONLY)) {
  50                 s->s_flags |= MS_RDONLY;
  51                 printk(KERN_ERR "    File system has been set read-only\n");
  52                 set_disk_ro_uevent(s->s_bdev->bd_disk, 1);
  53         }
  54 }
  55 EXPORT_SYMBOL_GPL(fat_fs_error);
  56
  57 /* Flushes the number of free clusters on FAT32 */
  58 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
  59 int fat_clusters_flush(struct super_block *sb)
  60 {
  61         struct msdos_sb_info *sbi = MSDOS_SB(sb);
  62         struct buffer_head *bh;
  63         struct fat_boot_fsinfo *fsinfo;
  64
  65         if (sbi->fat_bits != 32)
  66                 return 0;
  67
  68         bh = sb_bread(sb, sbi->fsinfo_sector);
  69         if (bh == NULL) {
  70                 printk(KERN_ERR "FAT: bread failed in fat_clusters_flush\n");
  71                 return -EIO;
  72         }
  73
  74         fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
  75         /* Sanity check */
  76         if (!IS_FSINFO(fsinfo)) {
  77                 printk(KERN_ERR "FAT: Invalid FSINFO signature: "
  78                        "0x%08x, 0x%08x (sector = %lu)\n",
  79                        le32_to_cpu(fsinfo->signature1),
  80                        le32_to_cpu(fsinfo->signature2),
  81                        sbi->fsinfo_sector);
  82         } else {
  83                 if (sbi->free_clusters != -1)
  84                         fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
  85                 if (sbi->prev_free != -1)
  86                         fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
  87                 mark_buffer_dirty(bh);
  88         }
  89         brelse(bh);
  90
  91         return 0;
  92 }
  93
  94 /*
  95  * fat_chain_add() adds a new cluster to the chain of clusters represented
  96  * by inode.
  97  */
  98 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
  99 {
 100         struct super_block *sb = inode->i_sb;
 101         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 102         int ret, new_fclus, last;
 103
 104         /*
 105          * We must locate the last cluster of the file to add this new
 106          * one (new_dclus) to the end of the link list (the FAT).
 107          */
 108         last = new_fclus = 0;
 109         if (MSDOS_I(inode)->i_start) {
 110                 int fclus, dclus;
 111
 112                 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 113                 if (ret < 0)
 114                         return ret;
 115                 new_fclus = fclus + 1;
 116                 last = dclus;
 117         }
 118
 119         /* add new one to the last of the cluster chain */
 120         if (last) {
 121                 struct fat_entry fatent;
 122
 123                 fatent_init(&fatent);
 124                 ret = fat_ent_read(inode, &fatent, last);
 125                 if (ret >= 0) {
 126                         int wait = inode_needs_sync(inode);
 127                         ret = fat_ent_write(inode, &fatent, new_dclus, wait);
 128                         fatent_brelse(&fatent);
 129                 }
 130                 if (ret < 0)
 131                         return ret;
 132 //              fat_cache_add(inode, new_fclus, new_dclus);
 133         } else {
 134                 MSDOS_I(inode)->i_start = new_dclus;
 135                 MSDOS_I(inode)->i_logstart = new_dclus;
 136                 /*
 137                  * Since generic_write_sync() synchronizes regular files later,
 138                  * we sync here only directories.
 139                  */
 140                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
 141                         ret = fat_sync_inode(inode);
 142                         if (ret)
 143                                 return ret;
 144                 } else
 145                         mark_inode_dirty(inode);
 146         }
 147         if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
 148                 fat_fs_error(sb, "clusters badly computed (%d != %llu)",
 149                              new_fclus,
 150                              (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
 151                 fat_cache_inval_inode(inode);
 152         }
 153         inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
 154
 155         return 0;
 156 }
 157
 158 extern struct timezone sys_tz;
 159
 160 /*
 161  * The epoch of FAT timestamp is 1980.
 162  *     :  bits :     value
 163  * date:  0 -  4: day   (1 -  31)
 164  * date:  5 -  8: month (1 -  12)
 165  * date:  9 - 15: year  (0 - 127) from 1980
 166  * time:  0 -  4: sec   (0 -  29) 2sec counts
 167  * time:  5 - 10: min   (0 -  59)
 168  * time: 11 - 15: hour  (0 -  23)
 169  */
 170 #define SECS_PER_MIN    60
 171 #define SECS_PER_HOUR   (60 * 60)
 172 #define SECS_PER_DAY    (SECS_PER_HOUR * 24)
 173 #define UNIX_SECS_1980  315532800L
 174 #if BITS_PER_LONG == 64
 175 #define UNIX_SECS_2108  4354819200L
 176 #endif
 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 time_t 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 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 190 void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
 191                        __le16 __time, __le16 __date, u8 time_cs)
 192 {
 193         u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
 194         time_t second, 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 += (year * 365 + leap_day
 210                    + days_in_year[month] + day
 211                    + DAYS_DELTA) * SECS_PER_DAY;
 212
 213         if (!sbi->options.tz_utc)
 214                 second += sys_tz.tz_minuteswest * SECS_PER_MIN;
 215
 216         if (time_cs) {
 217                 ts->tv_sec = second + (time_cs / 100);
 218                 ts->tv_nsec = (time_cs % 100) * 10000000;
 219         } else {
 220                 ts->tv_sec = second;
 221                 ts->tv_nsec = 0;
 222         }
 223 }
 224
 225 /* Convert linear UNIX date to a FAT time/date pair. */
 226 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
 227                        __le16 *time, __le16 *date, u8 *time_cs)
 228 {
 229         time_t second = ts->tv_sec;
 230         time_t day, leap_day, month, year;
 231
 232         if (!sbi->options.tz_utc)
 233                 second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
 234
 235         /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
 236         if (second < UNIX_SECS_1980) {
 237                 *time = 0;
 238                 *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
 239                 if (time_cs)
 240                         *time_cs = 0;
 241                 return;
 242         }
 243 #if BITS_PER_LONG == 64
 244         if (second >= UNIX_SECS_2108) {
 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 #endif
 252
 253         day = second / SECS_PER_DAY - DAYS_DELTA;
 254         year = day / 365;
 255         leap_day = (year + 3) / 4;
 256         if (year > YEAR_2100)           /* 2100 isn't leap year */
 257                 leap_day--;
 258         if (year * 365 + leap_day > day)
 259                 year--;
 260         leap_day = (year + 3) / 4;
 261         if (year > YEAR_2100)           /* 2100 isn't leap year */
 262                 leap_day--;
 263         day -= year * 365 + leap_day;
 264
 265         if (IS_LEAP_YEAR(year) && day == days_in_year[3]) {
 266                 month = 2;
 267         } else {
 268                 if (IS_LEAP_YEAR(year) && day > days_in_year[3])
 269                         day--;
 270                 for (month = 1; month < 12; month++) {
 271                         if (days_in_year[month + 1] > day)
 272                                 break;
 273                 }
 274         }
 275         day -= days_in_year[month];
 276
 277         *time = cpu_to_le16(((second / SECS_PER_HOUR) % 24) << 11
 278                             | ((second / SECS_PER_MIN) % 60) << 5
 279                             | (second % SECS_PER_MIN) >> 1);
 280         *date = cpu_to_le16((year << 9) | (month << 5) | (day + 1));
 281         if (time_cs)
 282                 *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
 283 }
 284 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 285
 286 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 287 {
 288         int i, err = 0;
 289
 290         ll_rw_block(SWRITE, nr_bhs, bhs);
 291         for (i = 0; i < nr_bhs; i++) {
 292                 wait_on_buffer(bhs[i]);
 293                 if (buffer_eopnotsupp(bhs[i])) {
 294                         clear_buffer_eopnotsupp(bhs[i]);
 295                         err = -EOPNOTSUPP;
 296                 } else if (!err && !buffer_uptodate(bhs[i]))
 297                         err = -EIO;
 298         }
 299         return err;
 300 }
 301