Common Filesystem Interface

The VFS is the glue that enables system calls such as open(), read(), and write() to work regardless of the filesystem or underlying physical medium. It might not sound impressive these dayswe have long been taking such a feature for grantedbut it is a nontrivial feat for such generic system calls to work across all supported filesystems and media. More so, the system calls work between these different filesystems and mediawe can use standard system calls to copy or move files from one filesystem to another. In older operating systems (think DOS), this would never have worked; any access to a nonnative filesystem would require special tools. It is only because modern operating systems, Linux included, abstract access to the filesystems via a virtual interface that such interoperation and generic access is possible. New filesystems and new varieties of storage media can find their way into Linux, and programs need not be rewritten or even recompiled.