Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> wrote on 04/20/2020 11:04:33 AM:

> Yes, the problem is that copy_range subsystem handles block-status,
> when generic backup copying loop doesn't. I'm not sure that adding
> fallback into copy-range is a correct thing to do, at least it
> should be optional, enabled by flag.. But you don't need it for your problem,
> as it is already fixed upstream:
>
> You need to backport my commit 2d57511a88 "block/block-copy: use
> block_status" (together with 3 preparing patches before it, or with
> the whole series (including some refactoring after the 2d57511 commit)

Vladimir, thanks for the pointer to the "block/block-copy: use block_status" patch set. Those 4 patches do in fact solve the problem we were seeing.

- Bryan