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

[zhangqilong via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>]

> 
> 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

-> 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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