linux/fs/fat/misc.c
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   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 */
  23void __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}
  44EXPORT_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 */
  50void 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 */
  64int 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 */
 103int 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
 167extern struct timezone sys_tz;
 168
 169/*
 170 * The epoch of FAT timestamp is 1980.
 171 *     :  bits :     value
 172 * date:  0 -  4: day   (1 -  31)
 173 * date:  5 -  8: month (1 -  12)
 174 * date:  9 - 15: year  (0 - 127) from 1980
 175 * time:  0 -  4: sec   (0 -  29) 2sec counts
 176 * time:  5 - 10: min   (0 -  59)
 177 * time: 11 - 15: hour  (0 -  23)
 178 */
 179#define SECS_PER_MIN    60
 180#define SECS_PER_HOUR   (60 * 60)
 181#define SECS_PER_DAY    (SECS_PER_HOUR * 24)
 182/* days between 1.1.70 and 1.1.80 (2 leap days) */
 183#define DAYS_DELTA      (365 * 10 + 2)
 184/* 120 (2100 - 1980) isn't leap year */
 185#define YEAR_2100       120
 186#define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
 187
 188/* Linear day numbers of the respective 1sts in non-leap years. */
 189static time_t days_in_year[] = {
 190        /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
 191        0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 192};
 193
 194/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 195void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
 196                       __le16 __time, __le16 __date, u8 time_cs)
 197{
 198        u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
 199        time_t second, day, leap_day, month, year;
 200
 201        year  = date >> 9;
 202        month = max(1, (date >> 5) & 0xf);
 203        day   = max(1, date & 0x1f) - 1;
 204
 205        leap_day = (year + 3) / 4;
 206        if (year > YEAR_2100)           /* 2100 isn't leap year */
 207                leap_day--;
 208        if (IS_LEAP_YEAR(year) && month > 2)
 209                leap_day++;
 210
 211        second =  (time & 0x1f) << 1;
 212        second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
 213        second += (time >> 11) * SECS_PER_HOUR;
 214        second += (year * 365 + leap_day
 215                   + days_in_year[month] + day
 216                   + DAYS_DELTA) * SECS_PER_DAY;
 217
 218        if (!sbi->options.tz_set)
 219                second += sys_tz.tz_minuteswest * SECS_PER_MIN;
 220        else
 221                second -= sbi->options.time_offset * SECS_PER_MIN;
 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. */
 233void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
 234                       __le16 *time, __le16 *date, u8 *time_cs)
 235{
 236        struct tm tm;
 237        time_to_tm(ts->tv_sec,
 238                   (sbi->options.tz_set ? sbi->options.time_offset :
 239                   -sys_tz.tz_minuteswest) * SECS_PER_MIN, &tm);
 240
 241        /*  FAT can only support year between 1980 to 2107 */
 242        if (tm.tm_year < 1980 - 1900) {
 243                *time = 0;
 244                *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
 245                if (time_cs)
 246                        *time_cs = 0;
 247                return;
 248        }
 249        if (tm.tm_year > 2107 - 1900) {
 250                *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
 251                *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
 252                if (time_cs)
 253                        *time_cs = 199;
 254                return;
 255        }
 256
 257        /* from 1900 -> from 1980 */
 258        tm.tm_year -= 80;
 259        /* 0~11 -> 1~12 */
 260        tm.tm_mon++;
 261        /* 0~59 -> 0~29(2sec counts) */
 262        tm.tm_sec >>= 1;
 263
 264        *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
 265        *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
 266        if (time_cs)
 267                *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
 268}
 269EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 270
 271int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 272{
 273        int i, err = 0;
 274
 275        for (i = 0; i < nr_bhs; i++)
 276                write_dirty_buffer(bhs[i], WRITE);
 277
 278        for (i = 0; i < nr_bhs; i++) {
 279                wait_on_buffer(bhs[i]);
 280                if (!err && !buffer_uptodate(bhs[i]))
 281                        err = -EIO;
 282        }
 283        return err;
 284}
 285
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