Not without interfacing the with filesystem driver. You cannot and must not modify the filesystem on disk behind the driver's back while the filesystem is mounted. The only exception to this is filesystems built with that in mind, and which implement locking protocols that these applications would then have to implement. (Sun used to have such a filesystem for clusters. Each host in the cluster would mount the same filesystems from the same storage, and did locking on-disk in order to not step on each other.)