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  */
  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: 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  */
  77 int 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
 137 extern 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. */
 163 static 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). */
 169 void 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. */
 205 void 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 }
 263 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 264
 265 int 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