The RedirFS or redirecting file system is a layer between virtual file system switch (VFS) and file system drivers. It is implemented as an out-of-kernel module for Linux and it provides framework allowing modification of file system calls in the VFS layer. The RedirFS by itself does not provide any additional functionality and if it is loaded into the Linux kernel, it just occupies some memory space and it does practically nothing. The RedirFS is intended to be used by so-called filters. Filter is a linux kernel module (LKM) that uses the RedirFS framework. Each filter can add some useful functionality to the existing file systems like transparent compression, transparent encryption, merging contents of several directories into one, allowing writing to a read-only media and others.