Ceph » CephFS

Add the scrub stamps necessary for the scrubbing algorithm described in our forward scrub proposal; be efficient about any non-permanent data by putting it in the more() struct or a separate scrub_info() struct if appropriate. Permanent metadata needs to be cleaned up or cleared properly on rename (last_scrub_version will not be meaningful outside of the original containing directory). Add functionality so that given a single dirfrag, the MDS will do the scrub on it, and a temporary interface that lets us do so while the system is running.