The CIFS VFS is a virtual file system for Linux to allow access to servers and storage appliances compliant with the SNIA CIFS Specification version 1.0 or later. Popular servers such as Samba, Windows 2000, Windows XP and many others support CIFS by default.
The CIFS VFS provides some support for older servers based on the more primitive SMB (Server Message Block) protocol (you also can use the Linux file system smbfs as an alternative for accessing these). CIFS VFS is designed to take advantage of advanced network file system features such as locking, Unicode (advanced internationalization), hardlinks, dfs (hierarchical, replicated name space), distributed caching and uses native TCP names (rather than RFC1001, Netbios names). Unlike some other network file systems all key network function including authentication is provided in kernel (and changes to mount and/or a mount helper file are not required in order to enable the CIFS VFS).
The CIFS VFS was added to mainline Linux kernels in 2.5.42.