linux-kernel - Re: [f2fs-dev] [PATCH 1/2] f2fs: count writeback pages correctly

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Date:   Mon, 10 Apr 2017 19:14:29 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: count writeback pages correctly

On 2017/4/8 1:46, Jaegeuk Kim wrote:
> On 04/06, Chao Yu wrote:
>> Hi Jaegeuk,
>>
>> On 2017/4/6 2:02, Jaegeuk Kim wrote:
>>> This patch fixes # of outstanding writeback pages by checking its original page.
>>
>> Originally, we use bio_page to track encrypted page which is been writebacked,
>> there are two cases:
>> 1. background flush through .writepages: encrypted_page has no mapping info,
>> will not be tracked.
>> 2. synchronized GC through move_encrypted_block: encrypted_page is meta page,
>> will be tracked.
>>
>> So there is no problem with old code?
> 
> Consistency was fine, but why not tracking # of writebacked pages for encryption
> case?

Hmm.. because checkpoint doesn't care about writebacked pages of normal file, no
matter the file is encrypted or not. Right?

Thanks,

> 
> Thanks,
> 
>>
>> Thanks,
>>
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>> ---
>>>  fs/f2fs/data.c | 7 +++----
>>>  1 file changed, 3 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>> index 3d74c0ffa4c7..af3e849e96d2 100644
>>> --- a/fs/f2fs/data.c
>>> +++ b/fs/f2fs/data.c
>>> @@ -94,7 +94,6 @@ static void f2fs_write_end_io(struct bio *bio)
>>>  
>>>  	bio_for_each_segment_all(bvec, bio, i) {
>>>  		struct page *page = bvec->bv_page;
>>> -		enum count_type type = WB_DATA_TYPE(page);
>>>  
>>>  		if (IS_DUMMY_WRITTEN_PAGE(page)) {
>>>  			set_page_private(page, (unsigned long)NULL);
>>> @@ -113,7 +112,7 @@ static void f2fs_write_end_io(struct bio *bio)
>>>  			mapping_set_error(page->mapping, -EIO);
>>>  			f2fs_stop_checkpoint(sbi, true);
>>>  		}
>>> -		dec_page_count(sbi, type);
>>> +		dec_page_count(sbi, WB_DATA_TYPE(page));
>>>  		clear_cold_data(page);
>>>  		end_page_writeback(page);
>>>  	}
>>> @@ -389,7 +388,7 @@ int f2fs_submit_page_mbio(struct f2fs_io_info *fio)
>>>  	fio->submitted = 1;
>>>  
>>>  	if (!is_read)
>>> -		inc_page_count(sbi, WB_DATA_TYPE(bio_page));
>>> +		inc_page_count(sbi, WB_DATA_TYPE(fio->page));
>>>  
>>>  	down_write(&io->io_rwsem);
>>>  
>>> @@ -403,7 +402,7 @@ int f2fs_submit_page_mbio(struct f2fs_io_info *fio)
>>>  				fio->new_blkaddr & F2FS_IO_SIZE_MASK(sbi)) {
>>>  			err = -EAGAIN;
>>>  			if (!is_read)
>>> -				dec_page_count(sbi, WB_DATA_TYPE(bio_page));
>>> +				dec_page_count(sbi, WB_DATA_TYPE(fio->page));
>>>  			goto out_fail;
>>>  		}
>>>  		io->bio = __bio_alloc(sbi, fio->new_blkaddr,
>>>
> 
> .
>