linux-kernel - Re: [PATCH V4 0/7] loop: cleanup charging io to mem/blkcg

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Date:   Mon, 9 Aug 2021 08:41:59 +0200
From:   Christoph Hellwig <hch@....de>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Dan Schatzberg <schatzberg.dan@...il.com>
Subject: Re: [PATCH V4 0/7] loop: cleanup charging io to mem/blkcg

FYI, I am still of the firm opinion that the current cgroup support in
the loop driver needs to be reverted and be redone cleanly from scratch
without impacting the normal non-cgroup path at all.

On Fri, Aug 06, 2021 at 04:02:55PM +0800, Ming Lei wrote:
> Hello Guys,
> 
> Cleanup charging io to mem/blkcg a bit:
> 
> - avoid to store blkcg_css/memcg_css in loop_cmd, and store blkcg_css in
> loop_worker instead
> 
> - avoid to acquire ->lo_work_lock in IO path
> 
> - simplify blkcg_css query via xarray
> 
> - other misc cleanup
> 
> V4:
> 	- fix build failure in case of !CONFIG_CGROUPS: changed to use
> 	'struct cgroup_subsys_state' as parameter of the added memcg helper;
> 	meantime add helper loop_blkcg_css_id()
> 
> V3:
> 	- one patch style change in 7/7
> 	- rebase patch 4/7 against for-5.15/block
> 	- add acked-by tag
> 
> V2:
> 	- add helper of memcg_get_e_css
> 	- cleanup #ifdef
> 	- improve the last patch, as discussed with Dan Schatzberg
> 
> 
> Ming Lei (7):
>   mm: memcontrol: add helper of memcg_get_e_css
>   loop: clean up blkcg association
>   loop: conver timer for monitoring idle worker into dwork
>   loop: add __loop_free_idle_workers() for covering freeing workers in
>     clearing FD
>   loop: improve loop_process_work
>   loop: use xarray to store workers
>   loop: don't add worker into idle list
> 
>  drivers/block/loop.c       | 331 +++++++++++++++++++++----------------
>  drivers/block/loop.h       |   7 +-
>  include/linux/memcontrol.h |  10 ++
>  3 files changed, 201 insertions(+), 147 deletions(-)
> 
> -- 
> 2.31.1
---end quoted text---