323 lines
8.3 KiB
C
323 lines
8.3 KiB
C
/*
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* linux/fs/fat/misc.c
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*
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* Written 1992,1993 by Werner Almesberger
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* 22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
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* and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
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*/
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#include <linux/fs.h>
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#include <linux/msdos_fs.h>
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#include <linux/buffer_head.h>
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/*
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* fat_fs_panic reports a severe file system problem and sets the file system
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* read-only. The file system can be made writable again by remounting it.
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*/
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static char panic_msg[512];
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void fat_fs_panic(struct super_block *s, const char *fmt, ...)
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{
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int not_ro;
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va_list args;
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va_start (args, fmt);
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vsnprintf (panic_msg, sizeof(panic_msg), fmt, args);
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va_end (args);
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not_ro = !(s->s_flags & MS_RDONLY);
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if (not_ro)
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s->s_flags |= MS_RDONLY;
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printk(KERN_ERR "FAT: Filesystem panic (dev %s)\n"
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" %s\n", s->s_id, panic_msg);
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if (not_ro)
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printk(KERN_ERR " File system has been set read-only\n");
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}
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void lock_fat(struct super_block *sb)
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{
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down(&(MSDOS_SB(sb)->fat_lock));
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}
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void unlock_fat(struct super_block *sb)
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{
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up(&(MSDOS_SB(sb)->fat_lock));
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}
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/* Flushes the number of free clusters on FAT32 */
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/* XXX: Need to write one per FSINFO block. Currently only writes 1 */
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void fat_clusters_flush(struct super_block *sb)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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struct buffer_head *bh;
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struct fat_boot_fsinfo *fsinfo;
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if (sbi->fat_bits != 32)
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return;
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bh = sb_bread(sb, sbi->fsinfo_sector);
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if (bh == NULL) {
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printk(KERN_ERR "FAT bread failed in fat_clusters_flush\n");
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return;
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}
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fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
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/* Sanity check */
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if (!IS_FSINFO(fsinfo)) {
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printk(KERN_ERR "FAT: Did not find valid FSINFO signature.\n"
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" Found signature1 0x%08x signature2 0x%08x"
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" (sector = %lu)\n",
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le32_to_cpu(fsinfo->signature1),
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le32_to_cpu(fsinfo->signature2),
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sbi->fsinfo_sector);
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} else {
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if (sbi->free_clusters != -1)
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fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
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if (sbi->prev_free != -1)
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fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
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mark_buffer_dirty(bh);
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}
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brelse(bh);
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}
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/*
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* fat_add_cluster tries to allocate a new cluster and adds it to the
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* file represented by inode.
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*/
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int fat_add_cluster(struct inode *inode)
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{
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struct super_block *sb = inode->i_sb;
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int ret, count, limit, new_dclus, new_fclus, last;
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int cluster_bits = MSDOS_SB(sb)->cluster_bits;
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/*
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* We must locate the last cluster of the file to add this new
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* one (new_dclus) to the end of the link list (the FAT).
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*
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* In order to confirm that the cluster chain is valid, we
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* find out EOF first.
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*/
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last = new_fclus = 0;
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if (MSDOS_I(inode)->i_start) {
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int ret, fclus, dclus;
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ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
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if (ret < 0)
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return ret;
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new_fclus = fclus + 1;
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last = dclus;
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}
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/* find free FAT entry */
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lock_fat(sb);
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if (MSDOS_SB(sb)->free_clusters == 0) {
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unlock_fat(sb);
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return -ENOSPC;
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}
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limit = MSDOS_SB(sb)->clusters + 2;
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new_dclus = MSDOS_SB(sb)->prev_free + 1;
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for (count = 0; count < MSDOS_SB(sb)->clusters; count++, new_dclus++) {
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new_dclus = new_dclus % limit;
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if (new_dclus < 2)
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new_dclus = 2;
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ret = fat_access(sb, new_dclus, -1);
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if (ret < 0) {
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unlock_fat(sb);
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return ret;
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} else if (ret == FAT_ENT_FREE)
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break;
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}
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if (count >= MSDOS_SB(sb)->clusters) {
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MSDOS_SB(sb)->free_clusters = 0;
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unlock_fat(sb);
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return -ENOSPC;
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}
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ret = fat_access(sb, new_dclus, FAT_ENT_EOF);
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if (ret < 0) {
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unlock_fat(sb);
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return ret;
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}
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MSDOS_SB(sb)->prev_free = new_dclus;
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if (MSDOS_SB(sb)->free_clusters != -1)
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MSDOS_SB(sb)->free_clusters--;
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fat_clusters_flush(sb);
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unlock_fat(sb);
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/* add new one to the last of the cluster chain */
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if (last) {
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ret = fat_access(sb, last, new_dclus);
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if (ret < 0)
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return ret;
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// fat_cache_add(inode, new_fclus, new_dclus);
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} else {
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MSDOS_I(inode)->i_start = new_dclus;
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MSDOS_I(inode)->i_logstart = new_dclus;
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mark_inode_dirty(inode);
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}
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if (new_fclus != (inode->i_blocks >> (cluster_bits - 9))) {
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fat_fs_panic(sb, "clusters badly computed (%d != %lu)",
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new_fclus, inode->i_blocks >> (cluster_bits - 9));
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fat_cache_inval_inode(inode);
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}
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inode->i_blocks += MSDOS_SB(sb)->cluster_size >> 9;
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return new_dclus;
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}
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struct buffer_head *fat_extend_dir(struct inode *inode)
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{
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struct super_block *sb = inode->i_sb;
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struct buffer_head *bh, *res = NULL;
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int nr, sec_per_clus = MSDOS_SB(sb)->sec_per_clus;
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sector_t sector, last_sector;
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if (MSDOS_SB(sb)->fat_bits != 32) {
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if (inode->i_ino == MSDOS_ROOT_INO)
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return ERR_PTR(-ENOSPC);
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}
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nr = fat_add_cluster(inode);
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if (nr < 0)
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return ERR_PTR(nr);
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sector = ((sector_t)nr - 2) * sec_per_clus + MSDOS_SB(sb)->data_start;
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last_sector = sector + sec_per_clus;
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for ( ; sector < last_sector; sector++) {
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if ((bh = sb_getblk(sb, sector))) {
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memset(bh->b_data, 0, sb->s_blocksize);
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set_buffer_uptodate(bh);
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mark_buffer_dirty(bh);
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if (!res)
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res = bh;
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else
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brelse(bh);
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}
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}
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if (res == NULL)
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res = ERR_PTR(-EIO);
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if (inode->i_size & (sb->s_blocksize - 1)) {
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fat_fs_panic(sb, "Odd directory size");
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inode->i_size = (inode->i_size + sb->s_blocksize)
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& ~((loff_t)sb->s_blocksize - 1);
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}
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inode->i_size += MSDOS_SB(sb)->cluster_size;
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MSDOS_I(inode)->mmu_private += MSDOS_SB(sb)->cluster_size;
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return res;
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}
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/* Linear day numbers of the respective 1sts in non-leap years. */
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static int day_n[] = { 0,31,59,90,120,151,181,212,243,273,304,334,0,0,0,0 };
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/* JanFebMarApr May Jun Jul Aug Sep Oct Nov Dec */
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extern struct timezone sys_tz;
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/* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */
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int date_dos2unix(unsigned short time,unsigned short date)
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{
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int month,year,secs;
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/* first subtract and mask after that... Otherwise, if
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date == 0, bad things happen */
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month = ((date >> 5) - 1) & 15;
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year = date >> 9;
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secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400*
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((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 &&
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month < 2 ? 1 : 0)+3653);
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/* days since 1.1.70 plus 80's leap day */
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secs += sys_tz.tz_minuteswest*60;
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return secs;
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}
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/* Convert linear UNIX date to a MS-DOS time/date pair. */
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void fat_date_unix2dos(int unix_date,__le16 *time, __le16 *date)
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{
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int day,year,nl_day,month;
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unix_date -= sys_tz.tz_minuteswest*60;
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/* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
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if (unix_date < 315532800)
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unix_date = 315532800;
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*time = cpu_to_le16((unix_date % 60)/2+(((unix_date/60) % 60) << 5)+
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(((unix_date/3600) % 24) << 11));
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day = unix_date/86400-3652;
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year = day/365;
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if ((year+3)/4+365*year > day) year--;
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day -= (year+3)/4+365*year;
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if (day == 59 && !(year & 3)) {
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nl_day = day;
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month = 2;
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}
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else {
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nl_day = (year & 3) || day <= 59 ? day : day-1;
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for (month = 0; month < 12; month++)
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if (day_n[month] > nl_day) break;
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}
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*date = cpu_to_le16(nl_day-day_n[month-1]+1+(month << 5)+(year << 9));
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}
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/* Returns the inode number of the directory entry at offset pos. If bh is
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non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
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returned in bh.
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AV. Most often we do it item-by-item. Makes sense to optimize.
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AV. OK, there we go: if both bh and de are non-NULL we assume that we just
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AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
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AV. It's done in fat_get_entry() (inlined), here the slow case lives.
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AV. Additionally, when we return -1 (i.e. reached the end of directory)
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AV. we make bh NULL.
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*/
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int fat__get_entry(struct inode *dir, loff_t *pos,struct buffer_head **bh,
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struct msdos_dir_entry **de, loff_t *i_pos)
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{
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struct super_block *sb = dir->i_sb;
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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sector_t phys, iblock;
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loff_t offset;
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int err;
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next:
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offset = *pos;
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if (*bh)
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brelse(*bh);
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*bh = NULL;
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iblock = *pos >> sb->s_blocksize_bits;
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err = fat_bmap(dir, iblock, &phys);
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if (err || !phys)
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return -1; /* beyond EOF or error */
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*bh = sb_bread(sb, phys);
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if (*bh == NULL) {
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printk(KERN_ERR "FAT: Directory bread(block %llu) failed\n",
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(unsigned long long)phys);
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/* skip this block */
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*pos = (iblock + 1) << sb->s_blocksize_bits;
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goto next;
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}
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offset &= sb->s_blocksize - 1;
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*pos += sizeof(struct msdos_dir_entry);
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*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
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*i_pos = ((loff_t)phys << sbi->dir_per_block_bits) + (offset >> MSDOS_DIR_BITS);
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return 0;
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}
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