From: Chao Yu <yuchao0@huawei.com>
To: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: <linux-kernel@vger.kernel.org>, <linux-f2fs-devel@lists.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH] f2fs: clear cold data flag if IO is not counted
Date: Wed, 17 Oct 2018 09:30:12 +0800 [thread overview]
Message-ID: <b3f5fe2f-e082-5641-372a-2a7bb331a20c@huawei.com> (raw)
In-Reply-To: <20181016031052.GA19956@jaegeuk-macbookpro.roam.corp.google.com>
On 2018/10/16 11:10, Jaegeuk Kim wrote:
> On 10/16, Chao Yu wrote:
>> On 2018/10/16 7:08, Jaegeuk Kim wrote:
>>> On 10/15, Chao Yu wrote:
>>>> On 2018/10/11 5:22, Jaegeuk Kim wrote:
>>>>> If we clear the cold data flag out of the writeback flow, we can miscount
>>>>> -1 by end_io.
>>>>
>>>> I didn't get it, which count do you mean?
>>>
>>> It's the number of dirty pages.
>>>
>>> Balancing F2FS Async:
>>> - IO (CP: 1, Data: -1, Flush: ( 0 0 1), Discard: ( 0 129304)) cmd: 0 undiscard: 0
Better to add such info in commit message. :)
>>>
>>
>> So I guess the race should be:
>>
>> GC thread: IRQ
>> - move_data_page()
>> - set_page_dirty()
>> - clear_cold_data()
>> - f2fs_write_end_io()
>> - type = WB_DATA_TYPE(page);
>> here, we get wrong type
>> - dec_page_count(sbi, type);
>> - f2fs_wait_on_page_writeback()
>>
>> How about relocate wait_writeback & set_page_dirty to avoid above race:
>
> Well, wait_on_stable_page() doesn't guarantee its end_io. So, I'm not sure
> this is the only case.
Yes, you're right, I missed that case.
Can you use git-revert to generate the patch? so we can remain original
commit info for better backward tracking.
How do you think pick up original patch I submitted:
https://lkml.org/lkml/2018/7/27/415
Thanks,
>
>>
>> move_data_page()
>>
>> retry:
>> f2fs_wait_on_page_writeback(page, DATA, true);
>> set_page_dirty(page);
>>
>> Thanks,
>>
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>>>> ---
>>>>> fs/f2fs/data.c | 4 ----
>>>>> 1 file changed, 4 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>>> index 29a9d3b8f709..4102799b5558 100644
>>>>> --- a/fs/f2fs/data.c
>>>>> +++ b/fs/f2fs/data.c
>>>>> @@ -2636,10 +2636,6 @@ static int f2fs_set_data_page_dirty(struct page *page)
>>>>> if (!PageUptodate(page))
>>>>> SetPageUptodate(page);
>>>>>
>>>>> - /* don't remain PG_checked flag which was set during GC */
>>>>> - if (is_cold_data(page))
>>>>> - clear_cold_data(page);
>>>>> -
>>>>> if (f2fs_is_atomic_file(inode) && !f2fs_is_commit_atomic_write(inode)) {
>>>>> if (!IS_ATOMIC_WRITTEN_PAGE(page)) {
>>>>> f2fs_register_inmem_page(inode, page);
>>>>>
>>>
>>> .
>>>
>
> .
>
next prev parent reply other threads:[~2018-10-17 1:30 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 21:22 [PATCH] f2fs: clear cold data flag if IO is not counted Jaegeuk Kim
2018-10-15 12:38 ` [f2fs-dev] " Chao Yu
2018-10-15 23:08 ` Jaegeuk Kim
2018-10-16 1:31 ` Chao Yu
2018-10-16 3:10 ` Jaegeuk Kim
2018-10-17 1:30 ` Chao Yu [this message]
2018-10-17 2:43 ` Jaegeuk Kim
2018-10-17 2:34 ` [PATCH v2] " Jaegeuk Kim
2018-10-17 2:50 ` [f2fs-dev] " Chao Yu
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