On Wed, Apr 01, 2020 at 12:25:11PM +0200, Jan Kara wrote: > > - Applications must call statx to discover the current S_DAX state. > > > > - There exists an advisory file inode flag FS_XFLAG_DAX that can be > > changed on files that have no blocks allocated to them. Changing > > this flag does not necessarily change the S_DAX state immediately > > but programs can query the S_DAX state via statx. > > I generally like the proposal but I think the fact that toggling > FS_XFLAG_DAX will not have immediate effect on S_DAX will cause quite some > confusion and ultimately bug reports. I'm thinking whether we could somehow > improve this... For example an ioctl that would try to make set inode flags > effective by evicting the inode (and returning EBUSY if the eviction is > impossible for some reason)? I'd just return an error for that case, don't play silly games like evicting the inode.