Re: [f2fs-dev] [PATCH] f2fs: Fix data consistency in f2fs_move_file_range()

[Chao Yu <chao@kernel.org>]

On 2022/10/18 10:45, Zhang Qilong wrote:
> In the following case:
> process 1			process 2
>   ->open A
>    ->mmap
>     ->read # the first time
>     				 ->ioctl w/h F2FS_IOC_MOVE_RANGE
> 				        	# (range A->B)
>     ->read # the second time

How about checking B as well? Previous mapped data can still be accessed
after F2FS_IOC_MOVE_RANGE?

Thanks,

> 
> We will read old data at the second time. The root cause is that
> user still can see the previous source data after being moved. We
> fix it by adding truncating after __exchange_data_block.
> 
> Fixes: 4dd6f977fc77 ("f2fs: support an ioctl to move a range of data blocks")
> Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
> ---
> v2:
> - moving truncating to the range of f2fs_lock_op()
> 
> v3:
> - modify the title and commit message
> ---
>   fs/f2fs/file.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 82cda1258227..e9dfa41baf9e 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -2824,6 +2824,7 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in,
>   			goto out_src;
>   	}
>   
> +	filemap_invalidate_lock(src->i_mapping);
>   	f2fs_lock_op(sbi);
>   	ret = __exchange_data_block(src, dst, pos_in >> F2FS_BLKSIZE_BITS,
>   				pos_out >> F2FS_BLKSIZE_BITS,
> @@ -2835,7 +2836,9 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in,
>   		else if (dst_osize != dst->i_size)
>   			f2fs_i_size_write(dst, dst_osize);
>   	}
> +	truncate_pagecache_range(src, pos_in, pos_in + len - 1);
>   	f2fs_unlock_op(sbi);
> +	filemap_invalidate_unlock(src->i_mapping);
>   
>   	if (src != dst)
>   		f2fs_up_write(&F2FS_I(dst)->i_gc_rwsem[WRITE]);


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