On Tue, Apr 07, 2020 at 11:29:57AM -0700, ira.weiny@xxxxxxxxx wrote: > From: Ira Weiny <ira.weiny@xxxxxxxxx> > > We only support changing FS_XFLAG_DAX on directories. Files get their > flag from the parent directory on creation only. So no data > invalidation needs to happen. Which leads me to ask: how are users and/or admins supposed to remove the flag from regular files once it is set in the filesystem? Only being able to override the flag via the "dax=never" mount option means that once the flag is set, nobody can ever remove it and they can only globally turn off dax if it gets set incorrectly. It also means a global interrupt because all apps on the filesystem need to be stopped so the filesystem can be unmounted and mounted again with dax=never. This is highly unfriendly to admins and users. IOWs, we _must_ be able to clear this inode flag on regular inodes in some way. I don't care if it doesn't change the current in-memory state, but we must be able to clear the flags so that the next time the inodes are instantiated DAX is not enabled for those files... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
