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