On Mon, Mar 16, 2020 at 10:52:24AM +0100, Jan Kara wrote: > > This sounds reasonable to me. > > > > As for deprecating the mount option, I think at a minimum it needs to > > continue be accepted as an option even if it is ignored to not break > > existing setups. > > Agreed. But that's how we usually deprecate mount options. Also I'd say > that statx() support for reporting DAX state and some education of > programmers using DAX is required before we deprecate the mount option > since currently applications check 'dax' mount option to determine how much > memory they need to set aside for page cache before they consume everything > else on the machine... I don't even think we should deprecate it. It isn't painful to maintain and actually useful for testing. Instead we should expand it into a tristate: dax=off dax=flag dax=always where the existing "dax" option maps to "dax=always" and nodax maps to "dax=off". and dax=flag becomes the default for DAX capable devices.
