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 <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 *s, int report, const char *fmt, ...)
  24{
  25        struct fat_mount_options *opts = &MSDOS_SB(s)->options;
  26        va_list args;
  27
  28        if (report) {
  29                printk(KERN_ERR "FAT: Filesystem error (dev %s)\n", s->s_id);
  30
  31                printk(KERN_ERR "    ");
  32                va_start(args, fmt);
  33                vprintk(fmt, args);
  34                va_end(args);
  35                printk("\n");
  36        }
  37
  38        if (opts->errors == FAT_ERRORS_PANIC)
  39                panic("FAT: fs panic from previous error\n");
  40        else if (opts->errors == FAT_ERRORS_RO && !(s->s_flags & MS_RDONLY)) {
  41                s->s_flags |= MS_RDONLY;
  42                printk(KERN_ERR "FAT: Filesystem has been set read-only\n");
  43        }
  44}
  45EXPORT_SYMBOL_GPL(__fat_fs_error);
  46
  47/* Flushes the number of free clusters on FAT32 */
  48/* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
  49int fat_clusters_flush(struct super_block *sb)
  50{
  51        struct msdos_sb_info *sbi = MSDOS_SB(sb);
  52        struct buffer_head *bh;
  53        struct fat_boot_fsinfo *fsinfo;
  54
  55        if (sbi->fat_bits != 32)
  56                return 0;
  57
  58        bh = sb_bread(sb, sbi->fsinfo_sector);
  59        if (bh == NULL) {
  60                printk(KERN_ERR "FAT: bread failed in fat_clusters_flush\n");
  61                return -EIO;
  62        }
  63
  64        fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
  65        /* Sanity check */
  66        if (!IS_FSINFO(fsinfo)) {
  67                printk(KERN_ERR "FAT: Invalid FSINFO signature: "
  68                       "0x%08x, 0x%08x (sector = %lu)\n",
  69                       le32_to_cpu(fsinfo->signature1),
  70                       le32_to_cpu(fsinfo->signature2),
  71                       sbi->fsinfo_sector);
  72        } else {
  73                if (sbi->free_clusters != -1)
  74                        fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
  75                if (sbi->prev_free != -1)
  76                        fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
  77                mark_buffer_dirty(bh);
  78        }
  79        brelse(bh);
  80
  81        return 0;
  82}
  83
  84/*
  85 * fat_chain_add() adds a new cluster to the chain of clusters represented
  86 * by inode.
  87 */
  88int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
  89{
  90        struct super_block *sb = inode->i_sb;
  91        struct msdos_sb_info *sbi = MSDOS_SB(sb);
  92        int ret, new_fclus, last;
  93
  94        /*
  95         * We must locate the last cluster of the file to add this new
  96         * one (new_dclus) to the end of the link list (the FAT).
  97         */
  98        last = new_fclus = 0;
  99        if (MSDOS_I(inode)->i_start) {
 100                int fclus, dclus;
 101
 102                ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 103                if (ret < 0)
 104                        return ret;
 105                new_fclus = fclus + 1;
 106                last = dclus;
 107        }
 108
 109        /* add new one to the last of the cluster chain */
 110        if (last) {
 111                struct fat_entry fatent;
 112
 113                fatent_init(&fatent);
 114                ret = fat_ent_read(inode, &fatent, last);
 115                if (ret >= 0) {
 116                        int wait = inode_needs_sync(inode);
 117                        ret = fat_ent_write(inode, &fatent, new_dclus, wait);
 118                        fatent_brelse(&fatent);
 119                }
 120                if (ret < 0)
 121                        return ret;
 122//              fat_cache_add(inode, new_fclus, new_dclus);
 123        } else {
 124                MSDOS_I(inode)->i_start = new_dclus;
 125                MSDOS_I(inode)->i_logstart = new_dclus;
 126                /*
 127                 * Since generic_write_sync() synchronizes regular files later,
 128                 * we sync here only directories.
 129                 */
 130                if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
 131                        ret = fat_sync_inode(inode);
 132                        if (ret)
 133                                return ret;
 134                } else
 135                        mark_inode_dirty(inode);
 136        }
 137        if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
 138                fat_fs_error(sb, "clusters badly computed (%d != %llu)",
 139                             new_fclus,
 140                             (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
 141                fat_cache_inval_inode(inode);
 142        }
 143        inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
 144
 145        return 0;
 146}
 147
 148extern struct timezone sys_tz;
 149
 150/*
 151 * The epoch of FAT timestamp is 1980.
 152 *     :  bits :     value
 153 * date:  0 -  4: day   (1 -  31)
 154 * date:  5 -  8: month (1 -  12)
 155 * date:  9 - 15: year  (0 - 127) from 1980
 156 * time:  0 -  4: sec   (0 -  29) 2sec counts
 157 * time:  5 - 10: min   (0 -  59)
 158 * time: 11 - 15: hour  (0 -  23)
 159 */
 160#define SECS_PER_MIN    60
 161#define SECS_PER_HOUR   (60 * 60)
 162#define SECS_PER_DAY    (SECS_PER_HOUR * 24)
 163/* days between 1.1.70 and 1.1.80 (2 leap days) */
 164#define DAYS_DELTA      (365 * 10 + 2)
 165/* 120 (2100 - 1980) isn't leap year */
 166#define YEAR_2100       120
 167#define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
 168
 169/* Linear day numbers of the respective 1sts in non-leap years. */
 170static time_t days_in_year[] = {
 171        /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
 172        0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 173};
 174
 175/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 176void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
 177                       __le16 __time, __le16 __date, u8 time_cs)
 178{
 179        u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
 180        time_t second, day, leap_day, month, year;
 181
 182        year  = date >> 9;
 183        month = max(1, (date >> 5) & 0xf);
 184        day   = max(1, date & 0x1f) - 1;
 185
 186        leap_day = (year + 3) / 4;
 187        if (year > YEAR_2100)           /* 2100 isn't leap year */
 188                leap_day--;
 189        if (IS_LEAP_YEAR(year) && month > 2)
 190                leap_day++;
 191
 192        second =  (time & 0x1f) << 1;
 193        second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
 194        second += (time >> 11) * SECS_PER_HOUR;
 195        second += (year * 365 + leap_day
 196                   + days_in_year[month] + day
 197                   + DAYS_DELTA) * SECS_PER_DAY;
 198
 199        if (!sbi->options.tz_utc)
 200                second += sys_tz.tz_minuteswest * SECS_PER_MIN;
 201
 202        if (time_cs) {
 203                ts->tv_sec = second + (time_cs / 100);
 204                ts->tv_nsec = (time_cs % 100) * 10000000;
 205        } else {
 206                ts->tv_sec = second;
 207                ts->tv_nsec = 0;
 208        }
 209}
 210
 211/* Convert linear UNIX date to a FAT time/date pair. */
 212void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
 213                       __le16 *time, __le16 *date, u8 *time_cs)
 214{
 215        struct tm tm;
 216        time_to_tm(ts->tv_sec, sbi->options.tz_utc ? 0 :
 217                   -sys_tz.tz_minuteswest * 60, &tm);
 218
 219        /*  FAT can only support year between 1980 to 2107 */
 220        if (tm.tm_year < 1980 - 1900) {
 221                *time = 0;
 222                *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
 223                if (time_cs)
 224                        *time_cs = 0;
 225                return;
 226        }
 227        if (tm.tm_year > 2107 - 1900) {
 228                *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
 229                *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
 230                if (time_cs)
 231                        *time_cs = 199;
 232                return;
 233        }
 234
 235        /* from 1900 -> from 1980 */
 236        tm.tm_year -= 80;
 237        /* 0~11 -> 1~12 */
 238        tm.tm_mon++;
 239        /* 0~59 -> 0~29(2sec counts) */
 240        tm.tm_sec >>= 1;
 241
 242        *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
 243        *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
 244        if (time_cs)
 245                *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
 246}
 247EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 248
 249int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 250{
 251        int i, err = 0;
 252
 253        for (i = 0; i < nr_bhs; i++)
 254                write_dirty_buffer(bhs[i], WRITE);
 255
 256        for (i = 0; i < nr_bhs; i++) {
 257                wait_on_buffer(bhs[i]);
 258                if (!err && !buffer_uptodate(bhs[i]))
 259                        err = -EIO;
 260        }
 261        return err;
 262}
 263