\section{The Virtual Filesystem Switch}\label{sec-vfs}

The virtual filesystem switch, or vfs for short, allows the linux
kernel to run multiple filesystems at once.  This section documents
the vfs interface.

\subsection{VFS Data Structures}

/usr/include/linux/fs.h has many data structures that are used in
writing a filesystem\dots  So do {\sl name}\_fs*.h, where {\sl name\/}
is the name of the filesystem.