On Wed, Sep 15, 2021 at 01:27:47PM -0700, Dan Williams wrote: > > Yeah, Christoph suggested that we make the clearing operation explicit > > in a related thread a few weeks ago: > > https://lore.kernel.org/linux-fsdevel/YRtnlPERHfMZ23Tr@xxxxxxxxxxxxx/ > > That seemed to be tied to a proposal to plumb it all the way out to an > explicit fallocate() mode, not make it a silent side effect of > pwrite(). Yes. > > > > Each of the dm drivers has to add their own ->clear_poison operation > > that remaps the incoming (sector, len) parameters as appropriate for > > that device and then calls the lower device's ->clear_poison with the > > translated parameters. > > > > This (AFAICT) has already been done for dax_zero_page_range, so I sense > > that Dan is trying to save you a bunch of code plumbing work by nudging > > you towards doing s/dax_clear_poison/dax_zero_page_range/ to this series > > and then you only need patches 2-3. > > Yes, but it sounds like Christoph was saying don't overload > dax_zero_page_range(). I'd be ok splitting the difference and having a > new fallocate clear poison mode map to dax_zero_page_range() > internally. That was my gut feeling. If everyone feels 100% comfortable with zeroingas the mechanism to clear poisoning I'll cave in. The most important bit is that we do that through a dedicated DAX path instead of abusing the block layer even more. > > > > > > BTW, our customer doesn't care about creating dax volume thru DM, so. > > > > They might not care, but anything going upstream should work in the > > general case. > > Agree. I'm really worried about both patartitions on DAX and DM passing through DAX because they deeply bind DAX to the block layer, which is just a bad idea. I think we also need to sort that whole story out before removing the EXPERIMENTAL tags.
