Next Previous Contents 8. The Linux kernel implements the concept of Virtual File System (VFS, originally Virtual Filesystem Switch), so that it is (to a large degree) possible to separate actual "low-level" filesystem code from the rest of the kernel. The API of a filesystem is described below. This API was designed with things closely related to the ext2 filesystem in mind. For very different filesystems, like NFS, there are all kinds of problems. Four main objects: superblock, dentries, inodes, files The kernel keeps track of files using in-core inodes ("index nodes"), usually derived by the low-level filesystem from on-disk inodes. A file may have several names, and there is a layer of dentries ("directory entries") that represent pathnames, speeding up the lookup operation. Several processes may have the same file open for reading or writing, and file structures contai...