LXR linux/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 "fat.h"
  13
  14/*
  15 * fat_fs_error reports a file system problem that might indicate fa data
  16 * corruption/inconsistency. Depending on 'errors' mount option the
  17 * panic() is called, or error message is printed FAT and nothing is done,
  18 * or filesystem is remounted read-only (default behavior).
  19 * In case the file system is remounted read-only, it can be made writable
  20 * again by remounting it.
  21 */
  22void fat_fs_error(struct super_block *s, const char *fmt, ...)
  23{
  24        struct fat_mount_options *opts = &MSDOS_SB(s)->options;
  25        va_list args;
  26
  27        printk(KERN_ERR "FAT: Filesystem error (dev %s)\n", s->s_id);
  28
  29        printk(KERN_ERR "    ");
  30        va_start(args, fmt);
  31        vprintk(fmt, args);
  32        va_end(args);
  33        printk("\n");
  34
  35        if (opts->errors == FAT_ERRORS_PANIC)
  36                panic("    FAT fs panic from previous error\n");
  37        else if (opts->errors == FAT_ERRORS_RO && !(s->s_flags & MS_RDONLY)) {
  38                s->s_flags |= MS_RDONLY;
  39                printk(KERN_ERR "    File system has been set read-only\n");
  40        }
  41}
  42EXPORT_SYMBOL_GPL(fat_fs_error);
  43
  44/* Flushes the number of free clusters on FAT32 */
  45/* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
  46int fat_clusters_flush(struct super_block *sb)
  47{
  48        struct msdos_sb_info *sbi = MSDOS_SB(sb);
  49        struct buffer_head *bh;
  50        struct fat_boot_fsinfo *fsinfo;
  51
  52        if (sbi->fat_bits != 32)
  53                return 0;
  54
  55        bh = sb_bread(sb, sbi->fsinfo_sector);
  56        if (bh == NULL) {
  57                printk(KERN_ERR "FAT: bread failed in fat_clusters_flush\n");
  58                return -EIO;
  59        }
  60
  61        fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
  62        /* Sanity check */
  63        if (!IS_FSINFO(fsinfo)) {
  64                printk(KERN_ERR "FAT: Invalid FSINFO signature: "
  65                       "0x%08x, 0x%08x (sector = %lu)\n",
  66                       le32_to_cpu(fsinfo->signature1),
  67                       le32_to_cpu(fsinfo->signature2),
  68                       sbi->fsinfo_sector);
  69        } else {
  70                if (sbi->free_clusters != -1)
  71                        fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
  72                if (sbi->prev_free != -1)
  73                        fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
  74                mark_buffer_dirty(bh);
  75        }
  76        brelse(bh);
  77
  78        return 0;
  79}
  80
  81/*
  82 * fat_chain_add() adds a new cluster to the chain of clusters represented
  83 * by inode.
  84 */
  85int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
  86{
  87        struct super_block *sb = inode->i_sb;
  88        struct msdos_sb_info *sbi = MSDOS_SB(sb);
  89        int ret, new_fclus, last;
  90
  91        /*
  92         * We must locate the last cluster of the file to add this new
  93         * one (new_dclus) to the end of the link list (the FAT).
  94         */
  95        last = new_fclus = 0;
  96        if (MSDOS_I(inode)->i_start) {
  97                int fclus, dclus;
  98
  99                ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 100                if (ret < 0)
 101                        return ret;
 102                new_fclus = fclus + 1;
 103                last = dclus;
 104        }
 105
 106        /* add new one to the last of the cluster chain */
 107        if (last) {
 108                struct fat_entry fatent;
 109
 110                fatent_init(&fatent);
 111                ret = fat_ent_read(inode, &fatent, last);
 112                if (ret >= 0) {
 113                        int wait = inode_needs_sync(inode);
 114                        ret = fat_ent_write(inode, &fatent, new_dclus, wait);
 115                        fatent_brelse(&fatent);
 116                }
 117                if (ret < 0)
 118                        return ret;
 119//              fat_cache_add(inode, new_fclus, new_dclus);
 120        } else {
 121                MSDOS_I(inode)->i_start = new_dclus;
 122                MSDOS_I(inode)->i_logstart = new_dclus;
 123                /*
 124                 * Since generic_write_sync() synchronizes regular files later,
 125                 * we sync here only directories.
 126                 */
 127                if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
 128                        ret = fat_sync_inode(inode);
 129                        if (ret)
 130                                return ret;
 131                } else
 132                        mark_inode_dirty(inode);
 133        }
 134        if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
 135                fat_fs_error(sb, "clusters badly computed (%d != %llu)",
 136                             new_fclus,
 137                             (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
 138                fat_cache_inval_inode(inode);
 139        }
 140        inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
 141
 142        return 0;
 143}
 144
 145extern struct timezone sys_tz;
 146
 147/*
 148 * The epoch of FAT timestamp is 1980.
 149 *     :  bits :     value
 150 * date:  0 -  4: day   (1 -  31)
 151 * date:  5 -  8: month (1 -  12)
 152 * date:  9 - 15: year  (0 - 127) from 1980
 153 * time:  0 -  4: sec   (0 -  29) 2sec counts
 154 * time:  5 - 10: min   (0 -  59)
 155 * time: 11 - 15: hour  (0 -  23)
 156 */
 157#define SECS_PER_MIN    60
 158#define SECS_PER_HOUR   (60 * 60)
 159#define SECS_PER_DAY    (SECS_PER_HOUR * 24)
 160#define UNIX_SECS_1980  315532800L
 161#if BITS_PER_LONG == 64
 162#define UNIX_SECS_2108  4354819200L
 163#endif
 164/* days between 1.1.70 and 1.1.80 (2 leap days) */
 165#define DAYS_DELTA      (365 * 10 + 2)
 166/* 120 (2100 - 1980) isn't leap year */
 167#define YEAR_2100       120
 168#define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
 169
 170/* Linear day numbers of the respective 1sts in non-leap years. */
 171static time_t days_in_year[] = {
 172        /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
 173        0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 174};
 175
 176/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 177void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
 178                       __le16 __time, __le16 __date, u8 time_cs)
 179{
 180        u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
 181        time_t second, day, leap_day, month, year;
 182
 183        year  = date >> 9;
 184        month = max(1, (date >> 5) & 0xf);
 185        day   = max(1, date & 0x1f) - 1;
 186
 187        leap_day = (year + 3) / 4;
 188        if (year > YEAR_2100)           /* 2100 isn't leap year */
 189                leap_day--;
 190        if (IS_LEAP_YEAR(year) && month > 2)
 191                leap_day++;
 192
 193        second =  (time & 0x1f) << 1;
 194        second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
 195        second += (time >> 11) * SECS_PER_HOUR;
 196        second += (year * 365 + leap_day
 197                   + days_in_year[month] + day
 198                   + DAYS_DELTA) * SECS_PER_DAY;
 199
 200        if (!sbi->options.tz_utc)
 201                second += sys_tz.tz_minuteswest * SECS_PER_MIN;
 202
 203        if (time_cs) {
 204                ts->tv_sec = second + (time_cs / 100);
 205                ts->tv_nsec = (time_cs % 100) * 10000000;
 206        } else {
 207                ts->tv_sec = second;
 208                ts->tv_nsec = 0;
 209        }
 210}
 211
 212/* Convert linear UNIX date to a FAT time/date pair. */
 213void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
 214                       __le16 *time, __le16 *date, u8 *time_cs)
 215{
 216        time_t second = ts->tv_sec;
 217        time_t day, leap_day, month, year;
 218
 219        if (!sbi->options.tz_utc)
 220                second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
 221
 222        /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
 223        if (second < UNIX_SECS_1980) {
 224                *time = 0;
 225                *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
 226                if (time_cs)
 227                        *time_cs = 0;
 228                return;
 229        }
 230#if BITS_PER_LONG == 64
 231        if (second >= UNIX_SECS_2108) {
 232                *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
 233                *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
 234                if (time_cs)
 235                        *time_cs = 199;
 236                return;
 237        }
 238#endif
 239
 240        day = second / SECS_PER_DAY - DAYS_DELTA;
 241        year = day / 365;
 242        leap_day = (year + 3) / 4;
 243        if (year > YEAR_2100)           /* 2100 isn't leap year */
 244                leap_day--;
 245        if (year * 365 + leap_day > day)
 246                year--;
 247        leap_day = (year + 3) / 4;
 248        if (year > YEAR_2100)           /* 2100 isn't leap year */
 249                leap_day--;
 250        day -= year * 365 + leap_day;
 251
 252        if (IS_LEAP_YEAR(year) && day == days_in_year[3]) {
 253                month = 2;
 254        } else {
 255                if (IS_LEAP_YEAR(year) && day > days_in_year[3])
 256                        day--;
 257                for (month = 1; month < 12; month++) {
 258                        if (days_in_year[month + 1] > day)
 259                                break;
 260                }
 261        }
 262        day -= days_in_year[month];
 263
 264        *time = cpu_to_le16(((second / SECS_PER_HOUR) % 24) << 11
 265                            | ((second / SECS_PER_MIN) % 60) << 5
 266                            | (second % SECS_PER_MIN) >> 1);
 267        *date = cpu_to_le16((year << 9) | (month << 5) | (day + 1));
 268        if (time_cs)
 269                *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
 270}
 271EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 272
 273int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 274{
 275        int i, err = 0;
 276
 277        ll_rw_block(SWRITE, nr_bhs, bhs);
 278        for (i = 0; i < nr_bhs; i++) {
 279                wait_on_buffer(bhs[i]);
 280                if (buffer_eopnotsupp(bhs[i])) {
 281                        clear_buffer_eopnotsupp(bhs[i]);
 282                        err = -EOPNOTSUPP;
 283                } else if (!err && !buffer_uptodate(bhs[i]))
 284                        err = -EIO;
 285        }
 286        return err;
 287}
 288
 289