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. Jane, could you take over and try that? --D
