Re: [PATCH BUGFIX V3] block: add missing group association in bio-cloning functions

From	Nikolay Borisov <kernel@kyup.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH BUGFIX V3] block: add missing group association in bio-cloning functions
Date	2016-05-11 08:40 +0200
Message-ID	<rxvYm-2Hk-5@gated-at.bofh.it> (permalink)
References	<rxnxM-2xf-5@gated-at.bofh.it> <rxo0O-3aD-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 05/11/2016 01:01 AM, 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.
> 
> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
> ---
>  block/bio.c          | 15 +++++++++++++++
>  fs/btrfs/extent_io.c |  6 ------
>  include/linux/bio.h  |  3 +++
>  3 files changed, 18 insertions(+), 6 deletions(-)
> 

Just for reference something like that was already proposed (and tested)
before, though it never got merged :

https://www.redhat.com/archives/dm-devel/2016-March/msg00007.html

So you might also want to patch __bio_clone_fast to also apply this for
dm backed devices.

Otherwise:

Reviewed-by: Nikolay Borisov <kernel@kyup.com>

Thread

[PATCH BUGFIX] block: add missing group association in bio_split Paolo Valente <paolo.valente@linaro.org> - 2016-05-06 23:30 +0200
  Re: [PATCH BUGFIX] block: add missing group association in bio_split Jeff Moyer <jmoyer@redhat.com> - 2016-05-09 16:20 +0200
    Re: [PATCH BUGFIX] block: add missing group association in bio_split Jeff Moyer <jmoyer@redhat.com> - 2016-05-09 16:40 +0200
      Re: [PATCH BUGFIX] block: add missing group association in bio_split Paolo <paolo.valente@linaro.org> - 2016-05-09 16:40 +0200
        Re: [PATCH BUGFIX] block: add missing group association in bio_split Mark Brown <broonie@kernel.org> - 2016-05-09 17:00 +0200
          Re: [PATCH BUGFIX] block: add missing group association in bio_split Jens Axboe <axboe@kernel.dk> - 2016-05-09 20:00 +0200
            [PATCH BUGFIX] block: add missing group association in bio_split Paolo Valente <paolo.valente@linaro.org> - 2016-05-10 11:10 +0200
              Re: [PATCH BUGFIX] block: add missing group association in bio_split Jeff Moyer <jmoyer@redhat.com> - 2016-05-10 18:20 +0200
                Re: [PATCH BUGFIX] block: add missing group association in bio_split Paolo <paolo.valente@linaro.org> - 2016-05-10 19:10 +0200
                [PATCH BUGFIX] block: add missing group association in bio-cloning functions Paolo Valente <paolo.valente@linaro.org> - 2016-05-10 22:30 +0200
                Re: [PATCH BUGFIX] block: add missing group association in  bio-cloning functions Tejun Heo <tj@kernel.org> - 2016-05-10 22:50 +0200
                Re: [PATCH BUGFIX V2] block: add missing group association in  bio-cloning functions Tejun Heo <tj@kernel.org> - 2016-05-10 23:10 +0200
                [PATCH BUGFIX V2] block: add missing group association in bio-cloning functions Paolo Valente <paolo.valente@linaro.org> - 2016-05-10 23:10 +0200
                Re: [PATCH BUGFIX V2] block: add missing group association in bio-cloning functions Jeff Moyer <jmoyer@redhat.com> - 2016-05-10 23:40 +0200
                Re: [PATCH BUGFIX V2] block: add missing group association in  bio-cloning functions Paolo <paolo.valente@linaro.org> - 2016-05-10 23:50 +0200
                [PATCH BUGFIX V3] block: add missing group association in bio-cloning functions Paolo Valente <paolo.valente@linaro.org> - 2016-05-11 00:10 +0200
                Re: [PATCH BUGFIX V3] block: add missing group association in  bio-cloning functions Nikolay Borisov <kernel@kyup.com> - 2016-05-11 08:40 +0200
                Re: [PATCH BUGFIX V3] block: add missing group association in  bio-cloning functions Nikolay Borisov <kernel@kyup.com> - 2016-05-11 08:50 +0200
                Re: [PATCH BUGFIX V3] block: add missing group association in  bio-cloning functions Paolo <paolo.valente@linaro.org> - 2016-05-11 11:10 +0200
                [PATCH BUGFIX V4] block: add missing group association in bio-cloning functions Paolo Valente <paolo.valente@linaro.org> - 2016-05-11 11:30 +0200
        Re: [PATCH BUGFIX] block: add missing group association in bio_split Jens Axboe <axboe@kernel.dk> - 2016-05-09 17:00 +0200
  Re: [PATCH BUGFIX] block: add missing group association in bio_split Tejun Heo <tj@kernel.org> - 2016-05-09 17:30 +0200

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