Re: [PATCH] ovl: skip ovl_file_modified() for dedupe operations

On Fri, Apr 17, 2026 at 10:39 AM cuitao <[email protected]> wrote:
>
> DEDUPE only compares data blocks between two files without modifying
> file_out,

Not accurate.
It does not modify the data value.
It definitely does modify the file's metadata as well as its ctime.

> so there is no need to call ovl_file_modified() to sync
> attributes from the real inode. This aligns with the existing
> guard at the top of ovl_copyfile() which already skips copyattr
> and file_remove_privs for OVL_DEDUPE.
>
> Signed-off-by: cuitao <[email protected]>
> ---
>  fs/overlayfs/file.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> index 27cc07738f33..f1829f425f45 100644
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -572,7 +572,8 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
>         }
>
>         /* Update size */
> -       ovl_file_modified(file_out);
> +       if (op != OVL_DEDUPE)
> +               ovl_file_modified(file_out);
>

This is wrong because ovl_file_modified() also copied ctime.
You could update the comment above to say
/* Update size/mtime/ctime */
but this is not very important IMO.

Thanks,
Amir.