[dm-devel] dm: use gcd() to fix chunk_sectors limit stacking

[Mike Snitzer]

On Wed, Dec 02 2020 at  2:10am -0500,
JeffleXu <jefflexu at linux.alibaba.com> wrote:

> 
> 
> On 12/2/20 1:03 PM, Mike Snitzer wrote:
> > What you've done here is fairly chaotic/disruptive:
> > 1) you emailed a patch out that isn't needed or ideal, I dealt already
> >    staged a DM fix in linux-next for 5.10-rcX, see:
> >    https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-5.10-rcX&id=f28de262ddf09b635095bdeaf0e07ff507b3c41b
> 
> Then ti->type->io_hints() is still bypassed when type->iterate_devices()
> not defined?

Yes, the stacking of limits really is tightly coupled to device-based
influence.  Hypothetically some DM target that doesn't remap to any data
devices may want to override limits... in practice there isn't a need
for this.  If that changes we can take action to accommodate it.. but I'm
definitely not interested in modifying DM core in this area when there
isn't a demonstrated need.

Mike