Yesterday, while trying to unmount our (davfs2 mounted) work webdav server from my filesystem, I got device is busy.
Running sudo lsof | grep /mountpoint/of/davfs, revealed that the culprit was updatedb. Running man updatedb revealed that this is a command run to update a database for mlocate, most probably invoked by cron.
While I sometimes use locate, i don't need it to include all files on our work server (we got other search tools for that), and I definitely do not want this to interfere with me unmounting the filesystem.
 
    