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