linux-kernel - Re: [PATCH] f2fs: fix to account IO correctly

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Message-ID: <9e586616-5cfa-5515-008c-e7bba1e3c4a1@huawei.com>
Date:   Fri, 19 Oct 2018 10:23:31 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>
Subject: Re: [PATCH] f2fs: fix to account IO correctly

On 2018/10/19 3:06, Jaegeuk Kim wrote:
> 
> On 10/17, Chao Yu wrote:
>> Below race can cause reversed reference on F2FS_RD_DATA, there is
>> the same issue in f2fs_submit_page_bio(), fix them by relocate
>> __submit_bio() and inc_page_count.
>>
>> Thread A			Thread B
>> - f2fs_write_begin
>>  - f2fs_submit_page_read
>>  - __submit_bio
>> 				- f2fs_read_end_io
>> 				 - __read_end_io
>> 				 - dec_page_count(, F2FS_RD_DATA)
>>  - inc_page_count(, F2FS_RD_DATA)
> 
> Let me integrate the change into the original patch and test a bit.

IMO, it will be better to split this change into two, we can fix the
location of inc_page_count(, F2FS_RD_DATA) directly in your patch,
meanwhile we can add one more patch to fix the same issue in
f2fs_submit_page_bio(), in where the problem exists for long time, it needs
to send fixing patch to stable kernel mailing list.

Thanks,

> 
> Thanks,
> 
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>>  fs/f2fs/data.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index c03bd0c2ed22..8b9240762156 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -480,10 +480,10 @@ int f2fs_submit_page_bio(struct f2fs_io_info *fio)
>>  	}
>>  	bio_set_op_attrs(bio, fio->op, fio->op_flags);
>>  
>> -	__submit_bio(fio->sbi, bio, fio->type);
>> -
>>  	inc_page_count(fio->sbi, is_read_io(fio->op) ?
>>  			__read_io_type(page): WB_DATA_TYPE(fio->page));
>> +
>> +	__submit_bio(fio->sbi, bio, fio->type);
>>  	return 0;
>>  }
>>  
>> @@ -612,8 +612,8 @@ static int f2fs_submit_page_read(struct inode *inode, struct page *page,
>>  		return -EFAULT;
>>  	}
>>  	ClearPageError(page);
>> -	__submit_bio(F2FS_I_SB(inode), bio, DATA);
>>  	inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
>> +	__submit_bio(F2FS_I_SB(inode), bio, DATA);
>>  	return 0;
>>  }
>>  
>> -- 
>> 2.18.0.rc1
> 
> .
>