... File systems organize files into logical hierarchical structures with directories, soft links and so on held in blocks on physical devices. Devices that can contain file systems are known as block devices. ... In the EXT2 file system, the inode is the basic building block; every file and directory in the file system is described by one and only one inode. ... This VFS inode may be in the inode cache or it might have to be read from the block device supporting the file system of the mount point. ...