Re: [f2fs-dev] 答复: 答复: [PATCH -next] f2fs: adding truncate page cache after being moved

[Chao Yu <chao@kernel.org>]

On 2022/9/13 14:10, Chao Yu wrote:
> On 2022/9/13 12:37, zhangqilong wrote:
>>>
>>> On 2022/9/13 11:41, zhangqilong wrote:
>>>>> On 2022/9/13 11:05, Zhang Qilong wrote:
>>>>>> If we do not truncate source page cache, user can still see the
>>>>>> previous source data after being moved. We fix it by adding
>>>>>> truncating after __exchange_data_block.
>>>>>>
>>>>>> Fixes:4dd6f977fc778 ("f2fs: support an ioctl to move a range of data
>>>>>> blocks")
>>>>>> Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
>>>>>> ---
>>>>>>     fs/f2fs/file.c | 4 ++++
>>>>>>     1 file changed, 4 insertions(+)
>>>>>>
>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index
>>>>>> 771f1f7f3690..e3ff648aa496 100644
>>>>>> --- a/fs/f2fs/file.c
>>>>>> +++ b/fs/f2fs/file.c
>>>>>> @@ -2789,6 +2789,10 @@ static int f2fs_move_file_range(struct file
>>>>> *file_in, loff_t pos_in,
>>>>>>         }
>>>>>>         f2fs_unlock_op(sbi);
>>>>>>
>>>>>> +    filemap_invalidate_lock(src->i_mapping);
>>>>>
>>>>> invalidate lock should cover __exchange_data_block()?
>>>>>
>>>>>> +    truncate_pagecache_range(src, pos_in, pos_in + len - 1);
>>>>>
>>>>> truncate_pagecache_range() should be called before
>>>>> __exchange_data_block()?
>>>>
>>>> I have tried it, but it do not work. So I move the truncate operation
>>>> to the back of __exchange_data_block that it works well. I don't know
>>>> much enough, what do you think of this issue.
>>>
>>> Can you describe details about the testcase?
>>>
>>> Thanks,
>>>
>>
>> Process 1                         process 2
>> -> open A
>> -> mmap
>>     Read the data and save
>>                                 -> ioctl with F2FS_IOC_MOVE_RANGE   A  ->  B
> 
> The ioctl only change the data on target file (B), so Process 1 needs to
> read and check data of source file (B)?

Sorry, too rush to send this, let me check your testcase...

Thanks,

> 
> Thanks,
> 
>>
>> -> mmap
>>     Read the data that offset is same with first time and save
>>
>> Compare the consistency of the data that read twice.
>>
> 
> 
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