fs/fat/prince-fat/fat-kmalloc/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/fs.h>
  10 #include <linux/msdos_fs.h>
  11 #include <linux/buffer_head.h>
  12
  13 /*
  14  * fat_fs_panic reports a severe file system problem and sets the file system
  15  * read-only. The file system can be made writable again by remounting it.
  16  */
  17
  18 static char panic_msg[512];
  19
  20 void fat_fs_panic(struct super_block *s, const char *fmt, ...)
  21 {
  22         int not_ro;
  23         va_list args;
  24
  25         va_start (args, fmt);
  26         vsnprintf (panic_msg, sizeof(panic_msg), fmt, args);
  27         va_end (args);
  28
  29         not_ro = !(s->s_flags & MS_RDONLY);
  30         if (not_ro)
  31                 s->s_flags |= MS_RDONLY;
  32
  33         printk(KERN_ERR "FAT: Filesystem panic (dev %s)\n"
  34                "    %s\n", s->s_id, panic_msg);
  35         if (not_ro)
  36                 printk(KERN_ERR "    File system has been set read-only\n");
  37 }
  38
  39 void lock_fat(struct super_block *sb)
  40 {
  41         down(&(MSDOS_SB(sb)->fat_lock));
  42 }
  43
  44 void unlock_fat(struct super_block *sb)
  45 {
  46         up(&(MSDOS_SB(sb)->fat_lock));
  47 }
  48
  49 /* Flushes the number of free clusters on FAT32 */
  50 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
  51 void fat_clusters_flush(struct super_block *sb)
  52 {
  53         struct msdos_sb_info *sbi = MSDOS_SB(sb);
  54         struct buffer_head *bh;
  55         struct fat_boot_fsinfo *fsinfo;
  56
  57         if (sbi->fat_bits != 32)
  58                 return;
  59
  60         bh = sb_bread(sb, sbi->fsinfo_sector);
  61         if (bh == NULL) {
  62                 printk(KERN_ERR "FAT bread failed in fat_clusters_flush\n");
  63                 return;
  64         }
  65
  66         fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
  67         /* Sanity check */
  68         if (!IS_FSINFO(fsinfo)) {
  69                 printk(KERN_ERR "FAT: Did not find valid FSINFO signature.\n"
  70                        "     Found signature1 0x%08x signature2 0x%08x"
  71                        " (sector = %lu)\n",
  72                        CF_LE_L(fsinfo->signature1), CF_LE_L(fsinfo->signature2),
  73                        sbi->fsinfo_sector);
  74         } else {
  75                 if (sbi->free_clusters != -1)
  76                         fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
  77                 if (sbi->prev_free != -1)
  78                         fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
  79                 mark_buffer_dirty(bh);
  80         }
  81         brelse(bh);
  82 }
  83
  84 /*
  85  * fat_add_cluster tries to allocate a new cluster and adds it to the
  86  * file represented by inode.
  87  */
  88 int fat_add_cluster(struct inode *inode)
  89 {
  90         struct super_block *sb = inode->i_sb;
  91         int ret, count, limit, new_dclus, new_fclus, last;
  92         int cluster_bits = MSDOS_SB(sb)->cluster_bits;
  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          * In order to confirm that the cluster chain is valid, we
  99          * find out EOF first.
 100          */
 101
 102
 103         last = new_fclus = 0;
 104         if (MSDOS_I(inode)->i_start) {
 105                 int ret, fclus, dclus;
 106
 107                 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 108                 if (ret < 0)
 109                         return ret;
 110                 new_fclus = fclus + 1;
 111                 last = dclus;
 112         }
 113
 114         /* find free FAT entry */
 115         lock_fat(sb);
 116
 117         if (MSDOS_SB(sb)->free_clusters == 0) {
 118                 unlock_fat(sb);
 119                 return -ENOSPC;
 120         }
 121
 122         limit = MSDOS_SB(sb)->clusters + 2;
 123         new_dclus = MSDOS_SB(sb)->prev_free + 1;
 124         for (count = 0; count < MSDOS_SB(sb)->clusters; count++, new_dclus++) {
 125                 new_dclus = new_dclus % limit;
 126                 if (new_dclus < 2)
 127                         new_dclus = 2;
 128
 129                 ret = fat_access(sb, new_dclus, -1);
 130                 if (ret < 0) {
 131                         unlock_fat(sb);
 132                         return ret;
 133                 } else if (ret == FAT_ENT_FREE)
 134                         break;
 135         }
 136         if (count >= MSDOS_SB(sb)->clusters) {
 137                 MSDOS_SB(sb)->free_clusters = 0;
 138                 unlock_fat(sb);
 139                 return -ENOSPC;
 140         }
 141
 142         ret = fat_access(sb, new_dclus, FAT_ENT_EOF);
 143         if (ret < 0) {
 144                 unlock_fat(sb);
 145                 return ret;
 146         }
 147
 148         MSDOS_SB(sb)->prev_free = new_dclus;
 149         if (MSDOS_SB(sb)->free_clusters != -1)
 150                 MSDOS_SB(sb)->free_clusters--;
 151         fat_clusters_flush(sb);
 152
 153         unlock_fat(sb);
 154
 155         /* add new one to the last of the cluster chain */
 156         if (last) {
 157                 ret = fat_access(sb, last, new_dclus);
 158                 if (ret < 0)
 159                         return ret;
 160                 fat_cache_add(inode, new_fclus, new_dclus);
 161         } else {
 162                 MSDOS_I(inode)->i_start = new_dclus;
 163                 MSDOS_I(inode)->i_logstart = new_dclus;
 164                 mark_inode_dirty(inode);
 165         }
 166         if (new_fclus != (inode->i_blocks >> (cluster_bits - 9))) {
 167                 fat_fs_panic(sb, "clusters badly computed (%d != %lu)",
 168                         new_fclus, inode->i_blocks >> (cluster_bits - 9));
 169                 fat_cache_inval_inode(inode);
 170         }
 171         inode->i_blocks += MSDOS_SB(sb)->cluster_size >> 9;
 172
 173         return new_dclus;
 174 }
 175
 176 struct buffer_head *fat_extend_dir(struct inode *inode)
 177 {
 178         struct super_block *sb = inode->i_sb;
 179         struct buffer_head *bh, *res = NULL;
 180         int nr, sec_per_clus = MSDOS_SB(sb)->sec_per_clus;
 181         sector_t sector, last_sector;
 182
 183
 184         if (MSDOS_SB(sb)->fat_bits != 32) {
 185                 if (inode->i_ino == MSDOS_ROOT_INO)
 186                         return ERR_PTR(-ENOSPC);
 187         }
 188
 189         nr = fat_add_cluster(inode);
 190         if (nr < 0)
 191                 return ERR_PTR(nr);
 192
 193         sector = ((sector_t)nr - 2) * sec_per_clus + MSDOS_SB(sb)->data_start;
 194         last_sector = sector + sec_per_clus;
 195         for ( ; sector < last_sector; sector++) {
 196                 if ((bh = sb_getblk(sb, sector))) {
 197                         memset(bh->b_data, 0, sb->s_blocksize);
 198                         set_buffer_uptodate(bh);
 199                         mark_buffer_dirty(bh);
 200                         if (!res)
 201                                 res = bh;
 202                         else
 203                                 brelse(bh);
 204                 }
 205         }
 206         if (res == NULL)
 207                 res = ERR_PTR(-EIO);
 208         if (inode->i_size & (sb->s_blocksize - 1)) {
 209                 fat_fs_panic(sb, "Odd directory size");
 210                 inode->i_size = (inode->i_size + sb->s_blocksize)
 211                         & ~((loff_t)sb->s_blocksize - 1);
 212         }
 213         inode->i_size += MSDOS_SB(sb)->cluster_size;
 214         MSDOS_I(inode)->mmu_private += MSDOS_SB(sb)->cluster_size;
 215
 216         return res;
 217 }
 218
 219 /* Linear day numbers of the respective 1sts in non-leap years. */
 220
 221 static int day_n[] = { 0,31,59,90,120,151,181,212,243,273,304,334,0,0,0,0 };
 222                   /* JanFebMarApr May Jun Jul Aug Sep Oct Nov Dec */
 223
 224
 225 extern struct timezone sys_tz;
 226
 227
 228 /* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */
 229
 230 int date_dos2unix(unsigned short time,unsigned short date)
 231 {
 232         int month,year,secs;
 233
 234         /* first subtract and mask after that... Otherwise, if
 235            date == 0, bad things happen */
 236         month = ((date >> 5) - 1) & 15;
 237         year = date >> 9;
 238         secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400*
 239             ((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 &&
 240             month < 2 ? 1 : 0)+3653);
 241                         /* days since 1.1.70 plus 80's leap day */
 242         secs += sys_tz.tz_minuteswest*60;
 243         return secs;
 244 }
 245
 246
 247 /* Convert linear UNIX date to a MS-DOS time/date pair. */
 248
 249 void fat_date_unix2dos(int unix_date,__le16 *time, __le16 *date)
 250 {
 251         int day,year,nl_day,month;
 252
 253         unix_date -= sys_tz.tz_minuteswest*60;
 254
 255         /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
 256         if (unix_date < 315532800)
 257                 unix_date = 315532800;
 258
 259         *time = cpu_to_le16((unix_date % 60)/2+(((unix_date/60) % 60) << 5)+
 260             (((unix_date/3600) % 24) << 11));
 261         day = unix_date/86400-3652;
 262         year = day/365;
 263         if ((year+3)/4+365*year > day) year--;
 264         day -= (year+3)/4+365*year;
 265         if (day == 59 && !(year & 3)) {
 266                 nl_day = day;
 267                 month = 2;
 268         }
 269         else {
 270                 nl_day = (year & 3) || day <= 59 ? day : day-1;
 271                 for (month = 0; month < 12; month++)
 272                         if (day_n[month] > nl_day) break;
 273         }
 274         *date = cpu_to_le16(nl_day-day_n[month-1]+1+(month << 5)+(year << 9));
 275 }
 276
 277
 278 /* Returns the inode number of the directory entry at offset pos. If bh is
 279    non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
 280    returned in bh.
 281    AV. Most often we do it item-by-item. Makes sense to optimize.
 282    AV. OK, there we go: if both bh and de are non-NULL we assume that we just
 283    AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
 284    AV. It's done in fat_get_entry() (inlined), here the slow case lives.
 285    AV. Additionally, when we return -1 (i.e. reached the end of directory)
 286    AV. we make bh NULL.
 287  */
 288
 289 int fat__get_entry(struct inode *dir, loff_t *pos,struct buffer_head **bh,
 290                    struct msdos_dir_entry **de, loff_t *i_pos)
 291 {
 292         struct super_block *sb = dir->i_sb;
 293         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 294         sector_t phys, iblock;
 295         loff_t offset;
 296         int err;
 297
 298 next:
 299         offset = *pos;
 300         if (*bh)
 301                 brelse(*bh);
 302
 303         *bh = NULL;
 304         iblock = *pos >> sb->s_blocksize_bits;
 305         err = fat_bmap(dir, iblock, &phys);
 306         if (err || !phys)
 307                 return -1;      /* beyond EOF or error */
 308
 309         *bh = sb_bread(sb, phys);
 310         if (*bh == NULL) {
 311                 printk(KERN_ERR "FAT: Directory bread(block %llu) failed\n",
 312                        (unsigned long long)phys);
 313                 /* skip this block */
 314                 *pos = (iblock + 1) << sb->s_blocksize_bits;
 315                 goto next;
 316         }
 317
 318         offset &= sb->s_blocksize - 1;
 319         *pos += sizeof(struct msdos_dir_entry);
 320         *de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
 321         *i_pos = ((loff_t)phys << sbi->dir_per_block_bits) + (offset >> MSDOS_DIR_BITS);
 322
 323         return 0;
 324 }