[dm-devel] [PATCH 0/6] Support DAX for device-mapper dm-linear devices

[Kani, Toshimitsu]

On Tue, 2016-06-21 at 09:41 -0400, Mike Snitzer wrote:
> On Mon, Jun 20 2016 at  6:22pm -0400,
> Mike Snitzer <snitzer at redhat.com> wrote:
> > 
> > On Mon, Jun 20 2016 at  5:28pm -0400,
> > Kani, Toshimitsu <toshi.kani at hpe.com> wrote:
> > 
 :
> > Looks good, I folded it in and tested it to work.  Pushed to my 'wip'
> > branch.
> > 
> > No longer seeing any corruption in my test that was using partitions to
> > span pmem devices with a dm-linear device.
> > 
> > Jens, any chance you'd be open to picking up the first 2 patches in this
> > series?  Or would you like to see them folded or something different?
>
> I'm now wondering if we'd be better off setting a new QUEUE_FLAG_DAX
> rather than establish GENHD_FL_DAX on the genhd?
> 
> It'd be quite a bit easier to allow upper layers (e.g. XFS and ext4) to
> check for a queue flag.

I think GENHD_FL_DAX is more appropriate since DAX does not use a request
queue, except for protecting the underlining device being disabled while
direct_access() is called (b2e0d1625e19).  

About protecting direct_access, this patch assumes that the underlining
device cannot be disabled until dtr() is called.  Is this correct?  If not,
I will need to call dax_map_atomic().

Thanks,
-Toshi