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

[Christoph Hellwig]

On Mon, Apr 11, 2022 at 01:33:58PM -0400, Mike Snitzer wrote:
> When bio_{alloc,init}_clone are passed a bdev, bio_init() will call
> bio_associate_blkg() so the __bio_clone() work to initialize blkcg
> isn't needed.

No, unfortunately it isn't as simple as that.  There are bios that do
not use the default cgroup and thus blkg, e.g. those that come from
cgroup writeback.