inode.c

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	    /* Force the superblock to a larger size here. */
	    sb->s_blocksize = blksize;
	    set_blocksize(sb->s_dev, blksize);
	  }
	else
	  {
	    /* The first read is always 1024 bytes */
	    sb->s_blocksize = 1024;
	    set_blocksize(sb->s_dev, 1024);
	  }
	bh = bread(sb->s_dev, 0, sb->s_blocksize);
	if (bh == NULL || !buffer_uptodate(bh)) {
		brelse (bh);
		goto out_no_bread;
	}

/*
 * The DOS3 partition size limit is *not* 32M as many people think.  
 * Instead, it is 64K sectors (with the usual sector size being
 * 512 bytes, leading to a 32M limit).
 * 
 * DOS 3 partition managers got around this problem by faking a 
 * larger sector size, ie treating multiple physical sectors as 
 * a single logical sector.
 * 
 * We can accommodate this scheme by adjusting our cluster size,
 * fat_start, and data_start by an appropriate value.
 *
 * (by Drew Eckhardt)
 */

#define ROUND_TO_MULTIPLE(n,m) ((n) && (m) ? (n)+(m)-1-((n)-1)%(m) : 0)
    /* don't divide by zero */

	b = (struct fat_boot_sector *) bh->b_data;
	logical_sector_size =
		CF_LE_W(get_unaligned((unsigned short *) &b->sector_size));
	sector_mult = logical_sector_size >> SECTOR_BITS;
	sbi->cluster_size = b->cluster_size*sector_mult;
	if (!sbi->cluster_size || (sbi->cluster_size & (sbi->cluster_size-1))) {
		printk("fatfs: bogus cluster size\n");
		brelse(bh);
		goto out_invalid;
	}
	for (sbi->cluster_bits=0;
	     1<<sbi->cluster_bits<sbi->cluster_size;
	     sbi->cluster_bits++)
		;
	sbi->cluster_bits += SECTOR_BITS;
	sbi->fats = b->fats;
	sbi->fat_start = CF_LE_W(b->reserved)*sector_mult;
	if (!b->fat_length && b->fat32_length) {
		struct fat_boot_fsinfo *fsinfo;

		/* Must be FAT32 */
		fat32 = 1;
		sbi->fat_length= CF_LE_L(b->fat32_length)*sector_mult;
		sbi->root_cluster = CF_LE_L(b->root_cluster);

		/* MC - if info_sector is 0, don't multiply by 0 */
		if(CF_LE_W(b->info_sector) == 0) {
			sbi->fsinfo_offset =
	 			logical_sector_size + 0x1e0;
		} else {
			sbi->fsinfo_offset =
				(CF_LE_W(b->info_sector) * logical_sector_size)
				+ 0x1e0;
		}
		if (sbi->fsinfo_offset + sizeof(struct fat_boot_fsinfo) > sb->s_blocksize) {
			printk("fat_read_super: Bad fsinfo_offset\n");
			brelse(bh);
			goto out_invalid;
		}
		fsinfo = (struct fat_boot_fsinfo *)
			&bh->b_data[sbi->fsinfo_offset];
		if (CF_LE_L(fsinfo->signature) != 0x61417272) {
			printk("fat_read_super: Did not find valid FSINFO "
				"signature. Found 0x%x\n",
				CF_LE_L(fsinfo->signature));
		} else {
			sbi->free_clusters = CF_LE_L(fsinfo->free_clusters);
		}
	} else {
		fat32 = 0;
		sbi->fat_length = CF_LE_W(b->fat_length)*sector_mult;
		sbi->root_cluster = 0;
		sbi->free_clusters = -1; /* Don't know yet */
	}
	sbi->dir_start= CF_LE_W(b->reserved)*sector_mult+
	    b->fats*sbi->fat_length;
	sbi->dir_entries =
		CF_LE_W(get_unaligned((unsigned short *) &b->dir_entries));
	sbi->data_start = sbi->dir_start+ROUND_TO_MULTIPLE((
	    sbi->dir_entries << MSDOS_DIR_BITS) >> SECTOR_BITS,
	    sector_mult);
	data_sectors = CF_LE_W(get_unaligned((unsigned short *) &b->sectors));
	if (!data_sectors) {
		data_sectors = CF_LE_L(b->total_sect);
	}
	data_sectors = data_sectors * sector_mult - sbi->data_start;
	error = !b->cluster_size || !sector_mult;
	if (!error) {
		sbi->clusters = b->cluster_size ? data_sectors/
		    b->cluster_size/sector_mult : 0;
		sbi->fat_bits = fat32 ? 32 :
			(fat ? fat :
			 (sbi->clusters > MSDOS_FAT12 ? 16 : 12));
		fat_clusters = sbi->fat_length*SECTOR_SIZE*8/
		    sbi->fat_bits;
		error = !sbi->fats || (sbi->dir_entries &
		    (MSDOS_DPS-1)) || sbi->clusters+2 > fat_clusters+
		    MSDOS_MAX_EXTRA || (logical_sector_size & (SECTOR_SIZE-1))
		    || !b->secs_track || !b->heads;
	}
	brelse(bh);
	set_blocksize(sb->s_dev, blksize);
	/*
		This must be done after the brelse because the bh is a dummy
		allocated by fat_bread (see buffer.c)
	*/
	sb->s_blocksize = blksize;    /* Using this small block size solves */
				/* the misfit with buffer cache and cluster */
				/* because clusters (DOS) are often aligned */
				/* on odd sectors. */
	sb->s_blocksize_bits = blksize == 512 ? 9 : (blksize == 1024 ? 10 : 11);
	if (!strcmp(cvf_format,"none"))
		i = -1;
	else
		i = detect_cvf(sb,cvf_format);
	if (i >= 0)
		error = cvf_formats[i]->mount_cvf(sb,cvf_options);
	else if (sb->s_blocksize == 512)
		sbi->cvf_format = &default_cvf;
	else
		sbi->cvf_format = &bigblock_cvf;
	if (error || debug) {
		/* The MSDOS_CAN_BMAP is obsolete, but left just to remember */
		printk("[MS-DOS FS Rel. 12,FAT %d,check=%c,conv=%c,"
		       "uid=%d,gid=%d,umask=%03o%s]\n",
		       sbi->fat_bits,opts.name_check,
		       opts.conversion,opts.fs_uid,opts.fs_gid,opts.fs_umask,
		       MSDOS_CAN_BMAP(sbi) ? ",bmap" : "");
		printk("[me=0x%x,cs=%d,#f=%d,fs=%d,fl=%ld,ds=%ld,de=%d,data=%ld,"
		       "se=%d,ts=%ld,ls=%d,rc=%ld,fc=%u]\n",
			b->media,sbi->cluster_size,
			sbi->fats,sbi->fat_start,
			sbi->fat_length,
		       sbi->dir_start,sbi->dir_entries,
		       sbi->data_start,
		       CF_LE_W(*(unsigned short *) &b->sectors),
		       (unsigned long)b->total_sect,logical_sector_size,
		       sbi->root_cluster,sbi->free_clusters);
		printk ("Transaction block size = %d\n",blksize);
	}
	if (i<0) if (sbi->clusters+2 > fat_clusters)
		sbi->clusters = fat_clusters-2;
	if (error)
		goto out_invalid;

	sb->s_magic = MSDOS_SUPER_MAGIC;
	/* set up enough so that it can read an inode */
	init_waitqueue_head(&sbi->fat_wait);
	init_MUTEX(&sbi->fat_lock);
	sbi->prev_free = 0;

	cp = opts.codepage ? opts.codepage : 437;
	sprintf(buf, "cp%d", cp);
	sbi->nls_disk = load_nls(buf);
	if (! sbi->nls_disk) {
		/* Fail only if explicit charset specified */
		if (opts.codepage != 0)
			goto out_fail;
		sbi->options.codepage = 0; /* already 0?? */
		sbi->nls_disk = load_nls_default();
	}

	sbi->nls_io = NULL;
	if (sbi->options.isvfat && !opts.utf8) {
		p = opts.iocharset ? opts.iocharset : CONFIG_NLS_DEFAULT;
		sbi->nls_io = load_nls(p);
		if (! sbi->nls_io)
			/* Fail only if explicit charset specified */
			if (opts.iocharset)
				goto out_unload_nls;
	}
	if (! sbi->nls_io)
		sbi->nls_io = load_nls_default();

	root_inode=new_inode(sb);
	if (!root_inode)
		goto out_unload_nls;
	root_inode->i_ino = MSDOS_ROOT_INO;
	fat_read_root(root_inode);
	insert_inode_hash(root_inode);
	sb->s_root = d_alloc_root(root_inode);
	if (!sb->s_root)
		goto out_no_root;
	if(i>=0) {
		sbi->cvf_format = cvf_formats[i];
		++cvf_format_use_count[i];
	}
	return sb;

out_no_root:
	printk("get root inode failed\n");
	iput(root_inode);
	unload_nls(sbi->nls_io);
out_unload_nls:
	unload_nls(sbi->nls_disk);
	goto out_fail;
out_invalid:
	if (!silent)
		printk("VFS: Can't find a valid MSDOS filesystem on dev %s.\n",
			kdevname(sb->s_dev));
	goto out_fail;
out_no_bread:
	printk("FAT bread failed\n");
out_fail:
	if (opts.iocharset) {
		printk("VFS: freeing iocharset=%s\n", opts.iocharset);
		kfree(opts.iocharset);
	}
	if(sbi->private_data)
		kfree(sbi->private_data);
	sbi->private_data=NULL;
 
	return NULL;
}

int fat_statfs(struct super_block *sb,struct statfs *buf)
{
	int free,nr;
       
	if (MSDOS_SB(sb)->cvf_format &&
	    MSDOS_SB(sb)->cvf_format->cvf_statfs)
		return MSDOS_SB(sb)->cvf_format->cvf_statfs(sb,buf,
						sizeof(struct statfs));
	  
	lock_fat(sb);
	if (MSDOS_SB(sb)->free_clusters != -1)
		free = MSDOS_SB(sb)->free_clusters;
	else {
		free = 0;
		for (nr = 2; nr < MSDOS_SB(sb)->clusters+2; nr++)
			if (!fat_access(sb,nr,-1)) free++;
		MSDOS_SB(sb)->free_clusters = free;
	}
	unlock_fat(sb);
	buf->f_type = sb->s_magic;
	buf->f_bsize = MSDOS_SB(sb)->cluster_size*SECTOR_SIZE;
	buf->f_blocks = MSDOS_SB(sb)->clusters;
	buf->f_bfree = free;
	buf->f_bavail = free;
	buf->f_namelen = MSDOS_SB(sb)->options.isvfat ? 260 : 12;
	return 0;
}

static int is_exec(char *extension)
{
	char *exe_extensions = "EXECOMBAT", *walk;

	for (walk = exe_extensions; *walk; walk += 3)
		if (!strncmp(extension, walk, 3))
			return 1;
	return 0;
}

static int fat_writepage(struct page *page)
{
	return block_write_full_page(page,fat_get_block);
}
static int fat_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page,fat_get_block);
}
static int fat_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
{
	return cont_prepare_write(page,from,to,fat_get_block,
		&MSDOS_I(page->mapping->host)->mmu_private);
}
static int _fat_bmap(struct address_space *mapping, long block)
{
	return generic_block_bmap(mapping,block,fat_get_block);
}
static struct address_space_operations fat_aops = {
	readpage: fat_readpage,
	writepage: fat_writepage,
	sync_page: block_sync_page,
	prepare_write: fat_prepare_write,
	commit_write: generic_commit_write,
	bmap: _fat_bmap
};

/* doesn't deal with root inode */
static void fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	int nr;

	INIT_LIST_HEAD(&MSDOS_I(inode)->i_fat_hash);
	MSDOS_I(inode)->i_location = 0;
	MSDOS_I(inode)->i_fat_inode = inode;
	inode->i_uid = sbi->options.fs_uid;
	inode->i_gid = sbi->options.fs_gid;
	inode->i_version = ++event;
	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
		inode->i_mode = MSDOS_MKMODE(de->attr,S_IRWXUGO &
		    ~sbi->options.fs_umask) | S_IFDIR;
		inode->i_op = sbi->dir_ops;
		inode->i_fop = &fat_dir_operations;

		MSDOS_I(inode)->i_start = CF_LE_W(de->start);
		if (sbi->fat_bits == 32) {
			MSDOS_I(inode)->i_start |=
				(CF_LE_W(de->starthi) << 16);
		}
		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
		inode->i_nlink = fat_subdirs(inode);
		    /* includes .., compensating for "self" */
#ifdef DEBUG
		if (!inode->i_nlink) {
			printk("directory %d: i_nlink == 0\n",inode->i_ino);
			inode->i_nlink = 1;
		}
#endif
		if ((nr = MSDOS_I(inode)->i_start) != 0)
			while (nr != -1) {
				inode->i_size += SECTOR_SIZE*sbi->cluster_size;
				if (!(nr = fat_access(sb,nr,-1))) {
					printk("Directory %ld: bad FAT\n",
					    inode->i_ino);
					break;
				}
			}
		MSDOS_I(inode)->mmu_private = inode->i_size;
	} else { /* not a directory */
		inode->i_mode = MSDOS_MKMODE(de->attr,
		    ((IS_NOEXEC(inode) || 
		      (sbi->options.showexec &&
		       !is_exec(de->ext)))
		    	? S_IRUGO|S_IWUGO : S_IRWXUGO)
		    & ~sbi->options.fs_umask) | S_IFREG;
		MSDOS_I(inode)->i_start = CF_LE_W(de->start);
		if (sbi->fat_bits == 32) {
			MSDOS_I(inode)->i_start |=
				(CF_LE_W(de->starthi) << 16);
		}
		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
		inode->i_size = CF_LE_L(de->size);
	        inode->i_op = &fat_file_inode_operations;
	        inode->i_fop = &fat_file_operations;
		inode->i_mapping->a_ops = &fat_aops;
		MSDOS_I(inode)->mmu_private = inode->i_size;
	}
	if(de->attr & ATTR_SYS)
		if (sbi->options.sys_immutable)
			inode->i_flags |= S_IMMUTABLE;
	MSDOS_I(inode)->i_attrs = de->attr & ATTR_UNUSED;
	/* this is as close to the truth as we can get ... */
	inode->i_blksize = sbi->cluster_size*SECTOR_SIZE;
	inode->i_blocks =
		((inode->i_size+inode->i_blksize-1)>>sbi->cluster_bits) *
		sbi->cluster_size;
	inode->i_mtime = inode->i_atime =
	    date_dos2unix(CF_LE_W(de->time),CF_LE_W(de->date));
	inode->i_ctime =
		MSDOS_SB(sb)->options.isvfat
		? date_dos2unix(CF_LE_W(de->ctime),CF_LE_W(de->cdate))
		: inode->i_mtime;
	MSDOS_I(inode)->i_ctime_ms = de->ctime_ms;
}

void fat_write_inode(struct inode *inode, int wait)
{
	struct super_block *sb = inode->i_sb;
	struct buffer_head *bh;
	struct msdos_dir_entry *raw_entry;
	int i_pos;

retry:
	i_pos = MSDOS_I(inode)->i_location;
	if (inode->i_ino == MSDOS_ROOT_INO || !i_pos) {
		return;
	}
	lock_kernel();
	if (!(bh = fat_bread(sb, i_pos >> MSDOS_DPB_BITS))) {
		printk("dev = %s, ino = %d\n", kdevname(inode->i_dev), i_pos);
		fat_fs_panic(sb, "msdos_write_inode: unable to read i-node block");
		unlock_kernel();
		return;
	}
	spin_lock(&fat_inode_lock);
	if (i_pos != MSDOS_I(inode)->i_location) {
		spin_unlock(&fat_inode_lock);
		fat_brelse(sb, bh);
		unlock_kernel();
		goto retry;
	}

	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
	    [i_pos & (MSDOS_DPB-1)];
	if (S_ISDIR(inode->i_mode)) {
		raw_entry->attr = ATTR_DIR;
		raw_entry->size = 0;
	}
	else {
		raw_entry->attr = ATTR_NONE;
		raw_entry->size = CT_LE_L(inode->i_size);
	}
	raw_entry->attr |= MSDOS_MKATTR(inode->i_mode) |
	    MSDOS_I(inode)->i_attrs;
	raw_entry->start = CT_LE_W(MSDOS_I(inode)->i_logstart);
	raw_entry->starthi = CT_LE_W(MSDOS_I(inode)->i_logstart >> 16);
	fat_date_unix2dos(inode->i_mtime,&raw_entry->time,&raw_entry->date);
	raw_entry->time = CT_LE_W(raw_entry->time);
	raw_entry->date = CT_LE_W(raw_entry->date);
	if (MSDOS_SB(sb)->options.isvfat) {
		fat_date_unix2dos(inode->i_ctime,&raw_entry->ctime,&raw_entry->cdate);
		raw_entry->ctime_ms = MSDOS_I(inode)->i_ctime_ms;
		raw_entry->ctime = CT_LE_W(raw_entry->ctime);
		raw_entry->cdate = CT_LE_W(raw_entry->cdate);
	}
	spin_unlock(&fat_inode_lock);
	fat_mark_buffer_dirty(sb, bh);
	fat_brelse(sb, bh);
	unlock_kernel();
}


int fat_notify_change(struct dentry * dentry, struct iattr * attr)
{
	struct super_block *sb = dentry->d_sb;
	struct inode *inode = dentry->d_inode;
	int error;

	/* FAT cannot truncate to a longer file */
	if (attr->ia_valid & ATTR_SIZE) {
		if (attr->ia_size > inode->i_size)
			return -EPERM;
	}

	error = inode_change_ok(inode, attr);
	if (error)
		return MSDOS_SB(sb)->options.quiet ? 0 : error;

	if (((attr->ia_valid & ATTR_UID) && 
	     (attr->ia_uid != MSDOS_SB(sb)->options.fs_uid)) ||
	    ((attr->ia_valid & ATTR_GID) && 
	     (attr->ia_gid != MSDOS_SB(sb)->options.fs_gid)) ||
	    ((attr->ia_valid & ATTR_MODE) &&
	     (attr->ia_mode & ~MSDOS_VALID_MODE)))
		error = -EPERM;

	if (error)
		return MSDOS_SB(sb)->options.quiet ? 0 : error;

	inode_setattr(inode, attr);

	if (IS_NOEXEC(inode) && !S_ISDIR(inode->i_mode))
		inode->i_mode &= S_IFMT | S_IRUGO | S_IWUGO;
	else
		inode->i_mode |= S_IXUGO;

	inode->i_mode = ((inode->i_mode & S_IFMT) | ((((inode->i_mode & S_IRWXU
	    & ~MSDOS_SB(sb)->options.fs_umask) | S_IRUSR) >> 6)*S_IXUGO)) &
	    ~MSDOS_SB(sb)->options.fs_umask;
	return 0;
}