Re: [PATCH BUGFIX V5] block: add missing group association in bio-cloning functions

From: Jens Axboe
Date: Wed Jul 27 2016 - 10:45:31 EST

On 07/26/2016 11:22 PM, Paolo Valente wrote:
When a bio is cloned, the newly created bio must be associated with
the same blkcg as the original bio (if BLK_CGROUP is enabled). If
this operation is not performed, then the new bio is not associated
with any group, and the group of the current task is returned when
the group of the bio is requested.

Depending on the cloning frequency, this may cause a large
percentage of the bios belonging to a given group to be treated
as if belonging to other groups (in most cases as if belonging to
the root group). The expected group isolation may thereby be broken.

This commit adds the missing association in bio-cloning functions.

Added for 4.8, thanks.

Jens Axboe