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SubjectRe: [PATCH v3 00/12] block: always associate blkg and refcount cleanup
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On 9/21/18 2:56 PM, Dennis Zhou wrote:
> Hi Jens,
>
> On Tue, Sep 11, 2018 at 02:41:25PM -0400, Dennis Zhou wrote:
>> Hi everyone,
>>
>> v3: a few minor fixes.
>> 0003: Updated the comment to bio_associate_blkg to reflect closest
>> association.
>> Removed a return branch in __bio_lookup_create.
>> 0009: Removed an unnecessary rcu_read_(un)lock pair.
>> 0010: Fixed blkg null pointer... blkg->blkcg => blkcg.
>>
>> This is rebased onto axboe#for-4.20/block 902d53914f64.
>>
>> From v2 below (updated):
>> ------
>> This is a followup to the patch series I sent out earlier [1] containing
>> the middle two points:
>> 1. always associate a bio with a blkg
>> 2. remove the extra css ref held by bios and utilize the blkg ref
>>
>> The major difference with v2 is that error handling on blkg creation
>> and association failure is handled more gracefully. Rather than having
>> the complex logic to fallback to root, failures walk up the blkg tree.
>> This seems more natural and less prone to error with the many possible
>> failure scenarios.
>>
>> Additionally, there are fixes for kbuild errors and some key details
>> overlooked by me in the first series that were pointed out in review.
>>
>> Modified from the first patchset:
>> First, both blk-throttle and blk-iolatency rely on blkg association
>> to enable their policies. Rather than each policy (and future policies)
>> implement this logic independently, this consolidates it such that
>> all bios are tagged with a blkg.
>>
>> Second, with the addition of always having a blkg reference, the blkcg
>> can now be referenced through it rather than maintaining an additional
>> pointer and reference. So let's clean this up.
>>
>> [1] https://lore.kernel.org/lkml/20180831015356.69796-1-dennisszhou@gmail.com/T
>>
>> This patchset contains the following 12 patches:
>> 0001-blkcg-fix-ref-count-issue-with-bio_blkcg-using-task_.patch
>> 0002-blkcg-update-blkg_lookup_create-to-do-locking.patch
>> 0003-blkcg-convert-blkg_lookup_create-to-find-closest-blk.patch
>> 0004-blkcg-always-associate-a-bio-with-a-blkg.patch
>> 0005-blkcg-consolidate-bio_issue_init-to-be-a-part-of-cor.patch
>> 0006-blkcg-associate-a-blkg-for-pages-being-evicted-by-sw.patch
>> 0007-blkcg-associate-writeback-bios-with-a-blkg.patch
>> 0008-blkcg-remove-bio-bi_css-and-instead-use-bio-bi_blkg.patch
>> 0009-blkcg-remove-additional-reference-to-the-css.patch
>> 0010-blkcg-cleanup-and-make-blk_get_rl-use-blkg_lookup_cr.patch
>> 0011-blkcg-change-blkg-reference-counting-to-use-percpu_r.patch
>> 0012-blkcg-rename-blkg_try_get-to-blkg_tryget.patch
>>
>> This patchset is on top of axboe#for-4.20/block 902d53914f64.
>>
>> diffstats below:
>>
>> Dennis Zhou (Facebook) (12):
>> blkcg: fix ref count issue with bio_blkcg using task_css
>> blkcg: update blkg_lookup_create to do locking
>> blkcg: convert blkg_lookup_create to find closest blkg
>> blkcg: always associate a bio with a blkg
>> blkcg: consolidate bio_issue_init to be a part of core
>> blkcg: associate a blkg for pages being evicted by swap
>> blkcg: associate writeback bios with a blkg
>> blkcg: remove bio->bi_css and instead use bio->bi_blkg
>> blkcg: remove additional reference to the css
>> blkcg: cleanup and make blk_get_rl use blkg_lookup_create
>> blkcg: change blkg reference counting to use percpu_ref
>> blkcg: rename blkg_try_get to blkg_tryget
>>
>> Documentation/admin-guide/cgroup-v2.rst | 8 +-
>> block/bfq-cgroup.c | 4 +-
>> block/bfq-iosched.c | 2 +-
>> block/bio.c | 158 ++++++++++++++++--------
>> block/blk-cgroup.c | 123 ++++++++++++------
>> block/blk-iolatency.c | 26 +---
>> block/blk-throttle.c | 13 +-
>> block/bounce.c | 4 +-
>> block/cfq-iosched.c | 4 +-
>> drivers/block/loop.c | 5 +-
>> drivers/md/raid0.c | 2 +-
>> fs/buffer.c | 10 +-
>> fs/ext4/page-io.c | 2 +-
>> include/linux/bio.h | 23 ++--
>> include/linux/blk-cgroup.h | 145 +++++++++++++++-------
>> include/linux/blk_types.h | 1 -
>> include/linux/cgroup.h | 2 +
>> include/linux/writeback.h | 5 +-
>> kernel/cgroup/cgroup.c | 48 +++++--
>> kernel/trace/blktrace.c | 4 +-
>> mm/page_io.c | 2 +-
>> 21 files changed, 381 insertions(+), 210 deletions(-)
>>
>> Thanks,
>> Dennis
>
> I reran some basic test again for sanity and it seems to be fine on my
> end. There are at least acks, and some reviewed-by's on the series. Is
> there anything else you think needs to be done before we let this bake
> in for-4.20/for-next?

Looks like it's good to go, I have applied it for 4.20. Thanks Dennis.

--
Jens Axboe

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