On Tue, Oct 17, 2017 at 5:23 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> If a non-merge dir in an overlay mount has an overlay.origin xattr, it
> means it was once an upper merge dir, which may contain whiteouts and
> then the lower dir was removed under it.
>
> Do not iterate real dir directly in this case to avoid exposing whiteouts.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/readdir.c | 29 +++++++++++++++++++++++++----
> 1 file changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
> index 55623b6635b6..ba44546ad1ed 100644
> --- a/fs/overlayfs/readdir.c
> +++ b/fs/overlayfs/readdir.c
> @@ -319,21 +319,42 @@ static inline int ovl_dir_read(struct path *realpath,
> return err;
> }
>
> +/* Can we iterate real dir directly? */
> +static bool ovl_dir_is_real(struct dentry *dir)
> +{
> + struct path realpath;
> + enum ovl_path_type type = ovl_path_real(dir, &realpath);
> +
> + if (OVL_TYPE_MERGE(type))
> + return false;
> +
> + /*
> + * Non-merge dir may contain whiteouts from a time it was a merge
> + * upper, before lower dir was removed under it and possibly before
> + * it was rotated from upper to lower layer.
> + */
> + return !ovl_check_origin_xattr(realpath.dentry);
This patch is okay, but I started wondering if
ovl_check_origin_xattr() should cache the "has origin" bit for
directories. Can be a followup patch, or we can leave it later.
Just thought I'd mention it as something to think about.
Thanks,
Miklos
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