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

["Kani, Toshimitsu" <toshi.kani@hpe.com>]

On Mon, 2016-06-20 at 14:00 -0400, Mike Snitzer wrote:
> On Mon, Jun 13 2016 at  6:57pm -0400,
> Mike Snitzer <snitzer@redhat.com> wrote:
> 
> > 
> > On Mon, Jun 13 2016 at  6:21pm -0400,
> > Toshi Kani <toshi.kani@hpe.com> wrote:
> > 
> > > 
> > > This patch-set adds DAX support to device-mapper dm-linear devices
> > > used by LVM.  It works with LVM commands as follows:
> > >  - Creation of a logical volume with all DAX capable devices (such
> > >    as pmem) sets the logical volume DAX capable as well.
> > >  - Once a logical volume is set to DAX capable, the volume may not
> > >    be extended with non-DAX capable devices.
> > > 
> > > The direct_access interface is added to dm and dm-linear to map
> > > a request to a target device.
> > > 
> > >  - Patch 1-2 introduce GENHD_FL_DAX flag to indicate DAX capability.
> > >  - Patch 3-4 add direct_access functions to dm and dm-linear.
> > >  - Patch 5-6 set GENHD_FL_DAX to dm when all targets are DAX capable.
> > > 
> > > ---
> > > Toshi Kani (6):
> > >  1/6 genhd: Add GENHD_FL_DAX to gendisk flags
> > >  2/6 block: Check GENHD_FL_DAX for DAX capability
> > >  3/6 dm: Add dm_blk_direct_access() for mapped device
> > >  4/6 dm-linear: Add linear_direct_access()
> > >  5/6 dm, dm-linear: Add dax_supported to dm_target
> > >  6/6 dm: Enable DAX support for mapper device
> > Thanks a lot for doing this.  I recently added it to my TODO so your
> > patches come at a great time.
> > 
> > I'll try to get to reviewing/testing your work by the end of this week.
>
> I rebased your patches on linux-dm.git's 'for-next' (which includes what
> I've already staged for the 4.8 merge window).  And I folded/changed
> some of the DM patches so that there are only 2 now (1 for DM core and 1
> for dm-linear).  Please see the 4 topmost commits in my 'wip' here:
> 
> http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=wip
> 
> Feel free to pick these patches up to use as the basis for continued
> work or re-posting of this set.. either that or I could post them as v2
> on your behalf.
> 
> As for testing, I've verified that basic IO works to a pmem-based DM
> linear device and that mixed table types are rejected as expected.

Great! I will send additional patch, add DAX support to dm-stripe, on top of
these once I finish my testing.

Thanks,
-Toshi