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/msdos_fs.h>
  12 #include <linux/buffer_head.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  */
  18 void 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
  36 EXPORT_SYMBOL(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 */
  40 void 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: Did not find valid FSINFO signature.\n"
  59                        "     Found signature1 0x%08x signature2 0x%08x"
  60                        " (sector = %lu)\n",
  61                        le32_to_cpu(fsinfo->signature1),
  62                        le32_to_cpu(fsinfo->signature2),
  63                        sbi->fsinfo_sector);
  64         } else {
  65                 if (sbi->free_clusters != -1)
  66                         fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
  67                 if (sbi->prev_free != -1)
  68                         fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
  69                 mark_buffer_dirty(bh);
  70                 if (sb->s_flags & MS_SYNCHRONOUS)
  71                         sync_dirty_buffer(bh);
  72         }
  73         brelse(bh);
  74 }
  75
  76 /*
  77  * fat_chain_add() adds a new cluster to the chain of clusters represented
  78  * by inode.
  79  */
  80 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
  81 {
  82         struct super_block *sb = inode->i_sb;
  83         struct msdos_sb_info *sbi = MSDOS_SB(sb);
  84         int ret, new_fclus, last;
  85
  86         /*
  87          * We must locate the last cluster of the file to add this new
  88          * one (new_dclus) to the end of the link list (the FAT).
  89          */
  90         last = new_fclus = 0;
  91         if (MSDOS_I(inode)->i_start) {
  92                 int fclus, dclus;
  93
  94                 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
  95                 if (ret < 0)
  96                         return ret;
  97                 new_fclus = fclus + 1;
  98                 last = dclus;
  99         }
 100
 101         /* add new one to the last of the cluster chain */
 102         if (last) {
 103                 struct fat_entry fatent;
 104
 105                 fatent_init(&fatent);
 106                 ret = fat_ent_read(inode, &fatent, last);
 107                 if (ret >= 0) {
 108                         int wait = inode_needs_sync(inode);
 109                         ret = fat_ent_write(inode, &fatent, new_dclus, wait);
 110                         fatent_brelse(&fatent);
 111                 }
 112                 if (ret < 0)
 113                         return ret;
 114 //              fat_cache_add(inode, new_fclus, new_dclus);
 115         } else {
 116                 MSDOS_I(inode)->i_start = new_dclus;
 117                 MSDOS_I(inode)->i_logstart = new_dclus;
 118                 /*
 119                  * Since generic_osync_inode() synchronize later if
 120                  * this is not directory, we don't here.
 121                  */
 122                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
 123                         ret = fat_sync_inode(inode);
 124                         if (ret)
 125                                 return ret;
 126                 } else
 127                         mark_inode_dirty(inode);
 128         }
 129         if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
 130                 fat_fs_panic(sb, "clusters badly computed (%d != %lu)",
 131                         new_fclus, inode->i_blocks >> (sbi->cluster_bits - 9));
 132                 fat_cache_inval_inode(inode);
 133         }
 134         inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
 135
 136         return 0;
 137 }
 138
 139 extern struct timezone sys_tz;
 140
 141 /* Linear day numbers of the respective 1sts in non-leap years. */
 142 static int day_n[] = {
 143    /* Jan  Feb  Mar  Apr   May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
 144         0,  31,  59,  90,  120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0, 0
 145 };
 146
 147 /* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */
 148 int date_dos2unix(unsigned short time, unsigned short date)
 149 {
 150         int month, year, secs;
 151
 152         /*
 153          * first subtract and mask after that... Otherwise, if
 154          * date == 0, bad things happen
 155          */
 156         month = ((date >> 5) - 1) & 15;
 157         year = date >> 9;
 158         secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400*
 159             ((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 &&
 160             month < 2 ? 1 : 0)+3653);
 161                         /* days since 1.1.70 plus 80's leap day */
 162         secs += sys_tz.tz_minuteswest*60;
 163         return secs;
 164 }
 165
 166 /* Convert linear UNIX date to a MS-DOS time/date pair. */
 167 void fat_date_unix2dos(int unix_date, __le16 *time, __le16 *date)
 168 {
 169         int day, year, nl_day, month;
 170
 171         unix_date -= sys_tz.tz_minuteswest*60;
 172
 173         /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
 174         if (unix_date < 315532800)
 175                 unix_date = 315532800;
 176
 177         *time = cpu_to_le16((unix_date % 60)/2+(((unix_date/60) % 60) << 5)+
 178             (((unix_date/3600) % 24) << 11));
 179         day = unix_date/86400-3652;
 180         year = day/365;
 181         if ((year+3)/4+365*year > day)
 182                 year--;
 183         day -= (year+3)/4+365*year;
 184         if (day == 59 && !(year & 3)) {
 185                 nl_day = day;
 186                 month = 2;
 187         } else {
 188                 nl_day = (year & 3) || day <= 59 ? day : day-1;
 189                 for (month = 0; month < 12; month++) {
 190                         if (day_n[month] > nl_day)
 191                                 break;
 192                 }
 193         }
 194         *date = cpu_to_le16(nl_day-day_n[month-1]+1+(month << 5)+(year << 9));
 195 }
 196
 197 EXPORT_SYMBOL(fat_date_unix2dos);
 198
 199 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 200 {
 201         int i, e, err = 0;
 202
 203         for (i = 0; i < nr_bhs; i++) {
 204                 lock_buffer(bhs[i]);
 205                 if (test_clear_buffer_dirty(bhs[i])) {
 206                         get_bh(bhs[i]);
 207                         bhs[i]->b_end_io = end_buffer_write_sync;
 208                         e = submit_bh(WRITE, bhs[i]);
 209                         if (!err && e)
 210                                 err = e;
 211                 } else
 212                         unlock_buffer(bhs[i]);
 213         }
 214         for (i = 0; i < nr_bhs; i++) {
 215                 wait_on_buffer(bhs[i]);
 216                 if (buffer_eopnotsupp(bhs[i])) {
 217                         clear_buffer_eopnotsupp(bhs[i]);
 218                         err = -EOPNOTSUPP;
 219                 } else if (!err && !buffer_uptodate(bhs[i]))
 220                         err = -EIO;
 221         }
 222         return err;
 223 }
 224
 225 EXPORT_SYMBOL(fat_sync_bhs);