Consider first the two file systems X and Y, depicted in Figure fig-vnode-fs-xyz. In this figure, the numbers near the node names represent the file/inode/vnode numbers of that file or directory within that particular file system. For example ``X5'' refers to the vnode of the directory /usr/local on file system X.
Let's also assume that X is a UFS (local) file system, and that Y is the /usr file system available on a remote file server named ``titan.'' We wish to perform the following NFS mount action: mount titan:/usr /usr.
The in-kernel actions that proceed, assuming that all export and mount permissions are successful, are the following: