Virtual File System (VFS)

File System Category
Disk-based file system
journal file system: provide backup file system, more security
FAT -> NTFS
Network file system
NFS, SMB(CIFS), Samba(Unix-based SMB), AFS...
Special file system
/proc, /dev, devfs...


File System Abstraction Layer
/tmp (in-memory file system - RAM disk)

Unix file system
Filesystem are mounted at a specific mount point in a global hierarchy known as a namespace.
mount point(nfs, \tmp)

Each component of a path is called a directory entry(dentry)

inode - file's metadata
superblock - filesystm metadata

Non-Unix filesystem still work in Linux(FAT, NTFS)
special processing done on the fly

VFS Objects

superblock, inode, dentry, file
[              static              ]


sync_fs() best effort
link() - create a inode
dentry cache (d-cache)
inode cache (i-cache)

fs_struct (Process decriptor's fs field)