inode.c

对minix代码进行注释

static int minix_statfs(struct dentry *dentry, struct kstatfs *buf)
{
//取文件系统的信息
	struct minix_sb_info *sbi = minix_sb(dentry->d_sb);
	buf->f_type = dentry->d_sb->s_magic;
	buf->f_bsize = dentry->d_sb->s_blocksize;
	buf->f_blocks = (sbi->s_nzones - sbi->s_firstdatazone) << sbi->s_log_zone_size;
	buf->f_bfree = minix_count_free_blocks(sbi);
	buf->f_bavail = buf->f_bfree;
	buf->f_files = sbi->s_ninodes;
	buf->f_ffree = minix_count_free_inodes(sbi);
	buf->f_namelen = sbi->s_namelen;
	return 0;
}

static int minix_get_block(struct inode *inode, sector_t block,
		    struct buffer_head *bh_result, int create)
{
	if (INODE_VERSION(inode) == MINIX_V1)
		return V1_minix_get_block(inode, block, bh_result, create);
	else
		return V2_minix_get_block(inode, block, bh_result, create);
}

static int minix_writepage(struct page *page, struct writeback_control *wbc)
{
	return block_write_full_page(page, minix_get_block, wbc);
}
static int minix_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page,minix_get_block);
}
static int minix_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
{
	return block_prepare_write(page,from,to,minix_get_block);
}
static sector_t minix_bmap(struct address_space *mapping, sector_t block)
{
	return generic_block_bmap(mapping,block,minix_get_block);
}
static const struct address_space_operations minix_aops = {
	.readpage = minix_readpage,
	.writepage = minix_writepage,
	.sync_page = block_sync_page,
	.prepare_write = minix_prepare_write,
	.commit_write = generic_commit_write,
	.bmap = minix_bmap
};

static struct inode_operations minix_symlink_inode_operations = {
	.readlink	= generic_readlink,
	.follow_link	= page_follow_link_light,
	.put_link	= page_put_link,
	.getattr	= minix_getattr,
};

void minix_set_inode(struct inode *inode, dev_t rdev)
{
	if (S_ISREG(inode->i_mode)) {
		inode->i_op = &minix_file_inode_operations;
		inode->i_fop = &minix_file_operations;
		inode->i_mapping->a_ops = &minix_aops;
	} else if (S_ISDIR(inode->i_mode)) {
		inode->i_op = &minix_dir_inode_operations;
		inode->i_fop = &minix_dir_operations;
		inode->i_mapping->a_ops = &minix_aops;
	} else if (S_ISLNK(inode->i_mode)) {
		inode->i_op = &minix_symlink_inode_operations;
		inode->i_mapping->a_ops = &minix_aops;
	} else
		init_special_inode(inode, inode->i_mode, rdev);
}

/*
 * The minix V1 function to read an inode.
 */
static void V1_minix_read_inode(struct inode * inode)
{
	struct buffer_head * bh;
	struct minix_inode * raw_inode;
	struct minix_inode_info *minix_inode = minix_i(inode);
	int i;

	raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
	if (!raw_inode) {
		make_bad_inode(inode);
		return;
	}
	inode->i_mode = raw_inode->i_mode;
	inode->i_uid = (uid_t)raw_inode->i_uid;
	inode->i_gid = (gid_t)raw_inode->i_gid;
	inode->i_nlink = raw_inode->i_nlinks;
	inode->i_size = raw_inode->i_size;
	inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = raw_inode->i_time;
	inode->i_mtime.tv_nsec = 0;
	inode->i_atime.tv_nsec = 0;
	inode->i_ctime.tv_nsec = 0;
	inode->i_blocks = inode->i_blksize = 0;
	for (i = 0; i < 9; i++)
		minix_inode->u.i1_data[i] = raw_inode->i_zone[i];
	//将磁盘inode的部分内容复制到内存inode中
	minix_set_inode(inode, old_decode_dev(raw_inode->i_zone[0]));
	//根据文件的不同类型设置i_op,i_fop,i_mapping->a_ops
	brelse(bh);
}

/*
 * The minix V2 function to read an inode.
 */
static void V2_minix_read_inode(struct inode * inode)
{
	struct buffer_head * bh;
	struct minix2_inode * raw_inode;
	struct minix_inode_info *minix_inode = minix_i(inode);
	int i;

	raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
	if (!raw_inode) {
		make_bad_inode(inode);
		return;
	}
	inode->i_mode = raw_inode->i_mode;
	inode->i_uid = (uid_t)raw_inode->i_uid;
	inode->i_gid = (gid_t)raw_inode->i_gid;
	inode->i_nlink = raw_inode->i_nlinks;
	inode->i_size = raw_inode->i_size;
	inode->i_mtime.tv_sec = raw_inode->i_mtime;
	inode->i_atime.tv_sec = raw_inode->i_atime;
	inode->i_ctime.tv_sec = raw_inode->i_ctime;
	inode->i_mtime.tv_nsec = 0;
	inode->i_atime.tv_nsec = 0;
	inode->i_ctime.tv_nsec = 0;
	inode->i_blocks = inode->i_blksize = 0;
	for (i = 0; i < 10; i++)
		minix_inode->u.i2_data[i] = raw_inode->i_zone[i];
	minix_set_inode(inode, old_decode_dev(raw_inode->i_zone[0]));
	brelse(bh);
}

/*
 * The global function to read an inode.
 */
static void minix_read_inode(struct inode * inode)
{
	if (INODE_VERSION(inode) == MINIX_V1)
		V1_minix_read_inode(inode);
	else
		V2_minix_read_inode(inode);
}

/*
 * The minix V1 function to synchronize an inode.
 */
static struct buffer_head * V1_minix_update_inode(struct inode * inode)
{
	struct buffer_head * bh;
	struct minix_inode * raw_inode;
	struct minix_inode_info *minix_inode = minix_i(inode);
	int i;

	raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
	//将指定的inode读入
	if (!raw_inode)
		return NULL;
	raw_inode->i_mode = inode->i_mode;
	raw_inode->i_uid = fs_high2lowuid(inode->i_uid);
	raw_inode->i_gid = fs_high2lowgid(inode->i_gid);
	raw_inode->i_nlinks = inode->i_nlink;
	raw_inode->i_size = inode->i_size;
	raw_inode->i_time = inode->i_mtime.tv_sec;
	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
		raw_inode->i_zone[0] = old_encode_dev(inode->i_rdev);
	else for (i = 0; i < 9; i++)
		raw_inode->i_zone[i] = minix_inode->u.i1_data[i];
	//填入要写入的信息
	mark_buffer_dirty(bh);
	//设置缓冲为脏
	return bh;
}

/*
 * The minix V2 function to synchronize an inode.
 */
static struct buffer_head * V2_minix_update_inode(struct inode * inode)
{
	struct buffer_head * bh;
	struct minix2_inode * raw_inode;
	struct minix_inode_info *minix_inode = minix_i(inode);
	int i;

	raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
	if (!raw_inode)
		return NULL;
	raw_inode->i_mode = inode->i_mode;
	raw_inode->i_uid = fs_high2lowuid(inode->i_uid);
	raw_inode->i_gid = fs_high2lowgid(inode->i_gid);
	raw_inode->i_nlinks = inode->i_nlink;
	raw_inode->i_size = inode->i_size;
	raw_inode->i_mtime = inode->i_mtime.tv_sec;
	raw_inode->i_atime = inode->i_atime.tv_sec;
	raw_inode->i_ctime = inode->i_ctime.tv_sec;
	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
		raw_inode->i_zone[0] = old_encode_dev(inode->i_rdev);
	else for (i = 0; i < 10; i++)
		raw_inode->i_zone[i] = minix_inode->u.i2_data[i];
	mark_buffer_dirty(bh);
	return bh;
}

static struct buffer_head *minix_update_inode(struct inode *inode)
{
//将指定的inode读入，填充新的内容，设置包含此inode的缓冲为脏
	if (INODE_VERSION(inode) == MINIX_V1)
		return V1_minix_update_inode(inode);
	else
		return V2_minix_update_inode(inode);
}

static int minix_write_inode(struct inode * inode, int wait)
{
	brelse(minix_update_inode(inode));
	return 0;
}

int minix_sync_inode(struct inode * inode)
{
	int err = 0;
	struct buffer_head *bh;

	bh = minix_update_inode(inode);
	if (bh && buffer_dirty(bh))
	{
		sync_dirty_buffer(bh);
		//开始写缓冲并等待写结束
		if (buffer_req(bh) && !buffer_uptodate(bh))
			//buffer_req:缓冲区中有io操作
			//buffer_uptodate:缓冲中包含可用数据
		{
			printk("IO error syncing minix inode [%s:%08lx]\n",
				inode->i_sb->s_id, inode->i_ino);
			err = -1;
		}
	}
	else if (!bh)
		err = -1;
	brelse (bh);
	return err;
}

int minix_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
	generic_fillattr(dentry->d_inode, stat);
	if (INODE_VERSION(dentry->d_inode) == MINIX_V1)
		stat->blocks = (BLOCK_SIZE / 512) * V1_minix_blocks(stat->size);
	else
		stat->blocks = (BLOCK_SIZE / 512) * V2_minix_blocks(stat->size);
	stat->blksize = BLOCK_SIZE;
	return 0;
}

/*
 * The function that is called for file truncation.
 */
void minix_truncate(struct inode * inode)
{
	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)))
		return;
	//如果文件不是普通文件、目录或连接则返回
	if (INODE_VERSION(inode) == MINIX_V1)
		V1_minix_truncate(inode);
	else
		V2_minix_truncate(inode);
}
get_sb_bdev
static int minix_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
	return (fs_type, flags, dev_name, data, minix_fill_super,
			   mnt);
	//分配并初始化一个磁盘文件系统的超级块
	//打开dev_name设备，...，调用minix_fill_super
	//访问磁盘上的超级块，填充超级块对象
}

static struct file_system_type minix_fs_type = {
	.owner		= THIS_MODULE,
//指向实现文件系统的模块的指针
	.name		= "minix",
	.get_sb		= minix_get_sb,
	//从磁盘上读取超级块，在安装文件系统时，
	//在内存中组装超级块
	.kill_sb	= kill_block_super,
	//删除超级块的方法
	.fs_flags	= FS_REQUIRES_DEV,
};

static int __init init_minix_fs(void)
{
	int err = init_inodecache();
	if (err)
		goto out1;
	err = register_filesystem(&minix_fs_type);
	if (err)
		goto out;
	return 0;
out:
	destroy_inodecache();
out1:
	return err;
}

static void __exit exit_minix_fs(void)
{
        unregister_filesystem(&minix_fs_type);
	destroy_inodecache();
}

module_init(init_minix_fs)
module_exit(exit_minix_fs)
MODULE_LICENSE("GPL");