Re: [PATCH] f2fs: fix to account IO correctly

From: Chao Yu
Date: Thu Oct 18 2018 - 22:23:35 EST


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@xxxxxxxxxx>
>> ---
>> 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
>
> .
>