What is a CDFS?
The term CDFS (CD File System) is used for both the Linux and Windows Operating Systems (OSs).
CDFS is a file system that was created for Linux in 1999 and exports all boot images and tracks on a CD as normal files.
On the Windows OS, CDFS is the driver file that is used to support CD-ROM players and replace the traditional MSCDEX driver used on MS-DOS.
http://www.tech-faq.com/cdfs.html