Re: [PATCH v5 2/7] dax: introduce dax device flag DAXDEV_RECOVERY

[Dan Williams]

On Thu, Feb 3, 2022 at 5:43 AM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>
> On Wed, Feb 02, 2022 at 09:27:42PM +0000, Jane Chu wrote:
> > Yeah, I see.  Would you suggest a way to pass the indication from
> > dax_iomap_iter to dax_direct_access that the caller intends the
> > callee to ignore poison in the range because the caller intends
> > to do recovery_write? We tried adding a flag to dax_direct_access, and
> > that wasn't liked if I recall.
>
> To me a flag seems cleaner than this magic, but let's wait for Dan to
> chime in.

So back in November I suggested modifying the kaddr, mainly to avoid
touching all the dax_direct_access() call sites [1]. However, now
seeing the code and Chrisoph's comment I think this either wants type
safety (e.g. 'dax_addr_t *'), or just add a new flag. Given both of
those options involve touching all dax_direct_access() call sites and
a @flags operation is more extensible if any other scenarios arrive
lets go ahead and plumb a flag and skip the magic.