US Patent 10140462 Stackable file system with user space policy management

A computing device and method for managing file access control policies on a computing device are disclosed. The method includes maintaining file-access policies in user space, receiving, at a kernel level, from a user in user space, a request to access a file, and directing the request from the kernel level to a file-policy manager in user space. At least one of the of the file-access policies is enforced in user space with the file-policy manager to grant or deny access to the file, and file operations are performed on the file using only kernel-level calls when access to the to the file is granted.