[dm-devel] block: remove redundant blk-cgroup init from __bio_clone

[Mike Snitzer]

On Sat, Apr 23 2022 at 12:55P -0400,
Christoph Hellwig <hch at infradead.org> wrote:

> So while I'm still diving into the somewhat invasive changes to
> optimize some of the cloning all we might relaly need for your
> use case should be this:
> 
> http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/blk-clone-no-bdev
> 
> Can you check if this helps you?

Passing NULL will be useful for targets that do call bio_set_dev() but
there are some that inherit the original bdev.  I'll audit all targets
and sort out how best to handle the conditional initialization to
avoid needless work.

This change is useful and a requirement for relevant follow-on DM
changes:

Reviewed-by: Mike Snitzer <snitzer at kernel.org>

Thanks.