[Ocfs2-devel] [PATCH 1/2] ocfs2: fix zero out valid data

[Junxiao Bi]

Anybody help review this?

Thanks,

Junxiao.

On 7/13/21 2:13 PM, Junxiao Bi wrote:
> If append-dio feature is enabled, direct-io write and fallocate could run
> in parallel to extend file size, fallocate used "orig_isize" to record
> i_size before taking "ip_alloc_sem", when ocfs2_zeroout_partial_cluster()
> zeroout EOF blocks, i_size maybe already extended by ocfs2_dio_end_io_write(),
> that will cause valid data zeroed out.
>
> Fixes: 1733438b1d06 ("ocfs2: fix data corruption by fallocate")
> Signed-off-by: Junxiao Bi <junxiao.bi at oracle.com>
> Cc: <stable at vger.kernel.org>
> ---
>   fs/ocfs2/file.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 775657943057..53bb46ce3cbb 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -1935,7 +1935,6 @@ static int __ocfs2_change_file_space(struct file *file, struct inode *inode,
>   		goto out_inode_unlock;
>   	}
>   
> -	orig_isize = i_size_read(inode);
>   	switch (sr->l_whence) {
>   	case 0: /*SEEK_SET*/
>   		break;
> @@ -1943,7 +1942,7 @@ static int __ocfs2_change_file_space(struct file *file, struct inode *inode,
>   		sr->l_start += f_pos;
>   		break;
>   	case 2: /*SEEK_END*/
> -		sr->l_start += orig_isize;
> +		sr->l_start += i_size_read(inode);
>   		break;
>   	default:
>   		ret = -EINVAL;
> @@ -1998,6 +1997,7 @@ static int __ocfs2_change_file_space(struct file *file, struct inode *inode,
>   		ret = -EINVAL;
>   	}
>   
> +	orig_isize = i_size_read(inode);
>   	/* zeroout eof blocks in the cluster. */
>   	if (!ret && change_size && orig_isize < size) {
>   		ret = ocfs2_zeroout_partial_cluster(inode, orig_isize,