On Wed, Sep 22, 2021 at 5:52 PM Darrick J. Wong [off-list ref] wrote:

I withdraw the patchset due to spiralling complexity and the need to get
back to the other hojillion things.

Dave now suggests creating a RWF_CLEAR_POISON/IOCB_CLEAR_POISON flag to
clear poison ahead of userspace using a regular write to reset the
storage.  Honestly I only though of zero writes because I though that
would lead to the least amount of back and forth, which was clearly
wrong.

Sorry Darrick, you really tried to do right by the feedback.

Jane, could you take over and try that?

Let's just solve the immediate problem for DAX in the easiest way
possible which is just Jane's original patches, but using the existing
dax_zero_page_range() operation in the DAX pwrite() failure path. The
only change would be to make sure that the pwrite() is page aligned,
and punt on the ability to clear poison on sub-page granularity for
now.