| /* |
| * linux/fs/fat/cache.c |
| * |
| * Written 1992,1993 by Werner Almesberger |
| * |
| * Mar 1999. AV. Changed cache, so that it uses the starting cluster instead |
| * of inode number. |
| * May 1999. AV. Fixed the bogosity with FAT32 (read "FAT28"). Fscking lusers. |
| */ |
| |
| #include <linux/fs.h> |
| #include <linux/msdos_fs.h> |
| #include <linux/buffer_head.h> |
| |
| static struct fat_cache *fat_cache,cache[FAT_CACHE]; |
| static spinlock_t fat_cache_lock = SPIN_LOCK_UNLOCKED; |
| |
| int __fat_access(struct super_block *sb, int nr, int new_value) |
| { |
| struct msdos_sb_info *sbi = MSDOS_SB(sb); |
| struct buffer_head *bh, *bh2, *c_bh, *c_bh2; |
| unsigned char *p_first, *p_last; |
| int copy, first, last, next, b; |
| |
| if (sbi->fat_bits == 32) { |
| first = last = nr*4; |
| } else if (sbi->fat_bits == 16) { |
| first = last = nr*2; |
| } else { |
| first = nr*3/2; |
| last = first+1; |
| } |
| b = sbi->fat_start + (first >> sb->s_blocksize_bits); |
| if (!(bh = sb_bread(sb, b))) { |
| printk(KERN_ERR "FAT: bread(block %d) in" |
| " fat_access failed\n", b); |
| return -EIO; |
| } |
| if ((first >> sb->s_blocksize_bits) == (last >> sb->s_blocksize_bits)) { |
| bh2 = bh; |
| } else { |
| if (!(bh2 = sb_bread(sb, b + 1))) { |
| brelse(bh); |
| printk(KERN_ERR "FAT: bread(block %d) in" |
| " fat_access failed\n", b + 1); |
| return -EIO; |
| } |
| } |
| if (sbi->fat_bits == 32) { |
| p_first = p_last = NULL; /* GCC needs that stuff */ |
| next = CF_LE_L(((__u32 *) bh->b_data)[(first & |
| (sb->s_blocksize - 1)) >> 2]); |
| /* Fscking Microsoft marketing department. Their "32" is 28. */ |
| next &= 0x0fffffff; |
| } else if (sbi->fat_bits == 16) { |
| p_first = p_last = NULL; /* GCC needs that stuff */ |
| next = CF_LE_W(((__u16 *) bh->b_data)[(first & |
| (sb->s_blocksize - 1)) >> 1]); |
| } else { |
| p_first = &((__u8 *)bh->b_data)[first & (sb->s_blocksize - 1)]; |
| p_last = &((__u8 *)bh2->b_data)[(first + 1) & (sb->s_blocksize - 1)]; |
| if (nr & 1) |
| next = ((*p_first >> 4) | (*p_last << 4)) & 0xfff; |
| else |
| next = (*p_first+(*p_last << 8)) & 0xfff; |
| } |
| if (new_value != -1) { |
| if (sbi->fat_bits == 32) { |
| ((__u32 *)bh->b_data)[(first & (sb->s_blocksize - 1)) >> 2] |
| = CT_LE_L(new_value); |
| } else if (sbi->fat_bits == 16) { |
| ((__u16 *)bh->b_data)[(first & (sb->s_blocksize - 1)) >> 1] |
| = CT_LE_W(new_value); |
| } else { |
| if (nr & 1) { |
| *p_first = (*p_first & 0xf) | (new_value << 4); |
| *p_last = new_value >> 4; |
| } |
| else { |
| *p_first = new_value & 0xff; |
| *p_last = (*p_last & 0xf0) | (new_value >> 8); |
| } |
| mark_buffer_dirty(bh2); |
| } |
| mark_buffer_dirty(bh); |
| for (copy = 1; copy < sbi->fats; copy++) { |
| b = sbi->fat_start + (first >> sb->s_blocksize_bits) |
| + sbi->fat_length * copy; |
| if (!(c_bh = sb_bread(sb, b))) |
| break; |
| if (bh != bh2) { |
| if (!(c_bh2 = sb_bread(sb, b+1))) { |
| brelse(c_bh); |
| break; |
| } |
| memcpy(c_bh2->b_data, bh2->b_data, sb->s_blocksize); |
| mark_buffer_dirty(c_bh2); |
| brelse(c_bh2); |
| } |
| memcpy(c_bh->b_data, bh->b_data, sb->s_blocksize); |
| mark_buffer_dirty(c_bh); |
| brelse(c_bh); |
| } |
| } |
| brelse(bh); |
| if (bh != bh2) |
| brelse(bh2); |
| return next; |
| } |
| |
| /* |
| * Returns the this'th FAT entry, -1 if it is an end-of-file entry. If |
| * new_value is != -1, that FAT entry is replaced by it. |
| */ |
| int fat_access(struct super_block *sb, int nr, int new_value) |
| { |
| int next; |
| |
| next = -EIO; |
| if (nr < 2 || MSDOS_SB(sb)->clusters + 2 <= nr) { |
| fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", nr); |
| goto out; |
| } |
| if (new_value == FAT_ENT_EOF) |
| new_value = EOF_FAT(sb); |
| |
| next = __fat_access(sb, nr, new_value); |
| if (next < 0) |
| goto out; |
| if (next >= BAD_FAT(sb)) |
| next = FAT_ENT_EOF; |
| out: |
| return next; |
| } |
| |
| void fat_cache_init(void) |
| { |
| static int initialized; |
| int count; |
| |
| spin_lock(&fat_cache_lock); |
| if (initialized) { |
| spin_unlock(&fat_cache_lock); |
| return; |
| } |
| fat_cache = &cache[0]; |
| for (count = 0; count < FAT_CACHE; count++) { |
| cache[count].sb = NULL; |
| cache[count].next = count == FAT_CACHE-1 ? NULL : |
| &cache[count+1]; |
| } |
| initialized = 1; |
| spin_unlock(&fat_cache_lock); |
| } |
| |
| |
| void fat_cache_lookup(struct inode *inode,int cluster,int *f_clu,int *d_clu) |
| { |
| struct fat_cache *walk; |
| int first = MSDOS_I(inode)->i_start; |
| |
| if (!first) |
| return; |
| spin_lock(&fat_cache_lock); |
| for (walk = fat_cache; walk; walk = walk->next) |
| if (inode->i_sb == walk->sb |
| && walk->start_cluster == first |
| && walk->file_cluster <= cluster |
| && walk->file_cluster > *f_clu) { |
| *d_clu = walk->disk_cluster; |
| #ifdef DEBUG |
| printk("cache hit: %d (%d)\n",walk->file_cluster,*d_clu); |
| #endif |
| if ((*f_clu = walk->file_cluster) == cluster) { |
| spin_unlock(&fat_cache_lock); |
| return; |
| } |
| } |
| spin_unlock(&fat_cache_lock); |
| #ifdef DEBUG |
| printk("cache miss\n"); |
| #endif |
| } |
| |
| |
| #ifdef DEBUG |
| static void list_cache(void) |
| { |
| struct fat_cache *walk; |
| |
| for (walk = fat_cache; walk; walk = walk->next) { |
| if (walk->sb) |
| printk("<%s,%d>(%d,%d) ", walk->sb->s_id, |
| walk->start_cluster, walk->file_cluster, |
| walk->disk_cluster); |
| else printk("-- "); |
| } |
| printk("\n"); |
| } |
| #endif |
| |
| |
| void fat_cache_add(struct inode *inode,int f_clu,int d_clu) |
| { |
| struct fat_cache *walk,*last; |
| int first = MSDOS_I(inode)->i_start; |
| |
| last = NULL; |
| spin_lock(&fat_cache_lock); |
| for (walk = fat_cache; walk->next; walk = (last = walk)->next) |
| if (inode->i_sb == walk->sb |
| && walk->start_cluster == first |
| && walk->file_cluster == f_clu) { |
| if (walk->disk_cluster != d_clu) { |
| printk(KERN_ERR "FAT: cache corruption" |
| " (ino %lu)\n", inode->i_ino); |
| spin_unlock(&fat_cache_lock); |
| fat_cache_inval_inode(inode); |
| return; |
| } |
| /* update LRU */ |
| if (last == NULL) { |
| spin_unlock(&fat_cache_lock); |
| return; |
| } |
| last->next = walk->next; |
| walk->next = fat_cache; |
| fat_cache = walk; |
| #ifdef DEBUG |
| list_cache(); |
| #endif |
| spin_unlock(&fat_cache_lock); |
| return; |
| } |
| walk->sb = inode->i_sb; |
| walk->start_cluster = first; |
| walk->file_cluster = f_clu; |
| walk->disk_cluster = d_clu; |
| last->next = NULL; |
| walk->next = fat_cache; |
| fat_cache = walk; |
| spin_unlock(&fat_cache_lock); |
| #ifdef DEBUG |
| list_cache(); |
| #endif |
| } |
| |
| |
| /* Cache invalidation occurs rarely, thus the LRU chain is not updated. It |
| fixes itself after a while. */ |
| |
| void fat_cache_inval_inode(struct inode *inode) |
| { |
| struct fat_cache *walk; |
| int first = MSDOS_I(inode)->i_start; |
| |
| spin_lock(&fat_cache_lock); |
| for (walk = fat_cache; walk; walk = walk->next) |
| if (walk->sb == inode->i_sb |
| && walk->start_cluster == first) |
| walk->sb = NULL; |
| spin_unlock(&fat_cache_lock); |
| } |
| |
| |
| void fat_cache_inval_dev(struct super_block *sb) |
| { |
| struct fat_cache *walk; |
| |
| spin_lock(&fat_cache_lock); |
| for (walk = fat_cache; walk; walk = walk->next) |
| if (walk->sb == sb) |
| walk->sb = 0; |
| spin_unlock(&fat_cache_lock); |
| } |
| |
| |
| static int fat_get_cluster(struct inode *inode, int cluster) |
| { |
| struct super_block *sb = inode->i_sb; |
| int nr,count; |
| |
| if (!(nr = MSDOS_I(inode)->i_start)) return 0; |
| if (!cluster) return nr; |
| count = 0; |
| for (fat_cache_lookup(inode, cluster, &count, &nr); |
| count < cluster; |
| count++) { |
| nr = fat_access(sb, nr, -1); |
| if (nr == FAT_ENT_EOF) { |
| fat_fs_panic(sb, "%s: request beyond EOF (ino %lu)", |
| __FUNCTION__, inode->i_ino); |
| return -EIO; |
| } else if (nr == FAT_ENT_FREE) { |
| fat_fs_panic(sb, "%s: invalid cluster chain (ino %lu)", |
| __FUNCTION__, inode->i_ino); |
| return -EIO; |
| } else if (nr < 0) |
| return nr; |
| } |
| fat_cache_add(inode, cluster, nr); |
| return nr; |
| } |
| |
| int fat_bmap(struct inode *inode, int sector) |
| { |
| struct super_block *sb = inode->i_sb; |
| struct msdos_sb_info *sbi = MSDOS_SB(sb); |
| int cluster, offset, last_block; |
| |
| if ((sbi->fat_bits != 32) && |
| (inode->i_ino == MSDOS_ROOT_INO || (S_ISDIR(inode->i_mode) && |
| !MSDOS_I(inode)->i_start))) { |
| if (sector >= sbi->dir_entries >> sbi->dir_per_block_bits) |
| return 0; |
| return sector + sbi->dir_start; |
| } |
| last_block = (MSDOS_I(inode)->mmu_private + (sb->s_blocksize - 1)) |
| >> sb->s_blocksize_bits; |
| if (sector >= last_block) |
| return 0; |
| |
| cluster = sector / sbi->cluster_size; |
| offset = sector % sbi->cluster_size; |
| cluster = fat_get_cluster(inode, cluster); |
| if (cluster < 0) |
| return cluster; |
| else if (!cluster) |
| return 0; |
| return (cluster - 2) * sbi->cluster_size + sbi->data_start + offset; |
| } |
| |
| |
| /* Free all clusters after the skip'th cluster. Doesn't use the cache, |
| because this way we get an additional sanity check. */ |
| |
| int fat_free(struct inode *inode,int skip) |
| { |
| struct super_block *sb = inode->i_sb; |
| int nr,last; |
| |
| if (!(nr = MSDOS_I(inode)->i_start)) return 0; |
| last = 0; |
| while (skip--) { |
| last = nr; |
| nr = fat_access(sb, nr, -1); |
| if (nr == FAT_ENT_EOF) |
| return 0; |
| else if (nr == FAT_ENT_FREE) { |
| fat_fs_panic(sb, "%s: invalid cluster chain (ino %lu)", |
| __FUNCTION__, inode->i_ino); |
| return -EIO; |
| } else if (nr < 0) |
| return nr; |
| } |
| if (last) { |
| fat_access(sb, last, FAT_ENT_EOF); |
| fat_cache_inval_inode(inode); |
| } else { |
| fat_cache_inval_inode(inode); |
| MSDOS_I(inode)->i_start = 0; |
| MSDOS_I(inode)->i_logstart = 0; |
| mark_inode_dirty(inode); |
| } |
| |
| lock_fat(sb); |
| while (nr != FAT_ENT_EOF) { |
| nr = fat_access(sb, nr, FAT_ENT_FREE); |
| if (nr < 0) |
| goto error; |
| else if (nr == FAT_ENT_FREE) { |
| fat_fs_panic(sb, "%s: deleting beyond EOF (ino %lu)", |
| __FUNCTION__, inode->i_ino); |
| nr = -EIO; |
| goto error; |
| } |
| if (MSDOS_SB(sb)->free_clusters != -1) |
| MSDOS_SB(sb)->free_clusters++; |
| inode->i_blocks -= (1 << MSDOS_SB(sb)->cluster_bits) >> 9; |
| } |
| fat_clusters_flush(sb); |
| nr = 0; |
| error: |
| unlock_fat(sb); |
| |
| return nr; |
| } |