On Sat, Jun 24, 2017 at 8:57 AM, zhangyi (F) <yi.zhang@xxxxxxxxxx> wrote:
> If an "impure && not merged" upper dir have left whiteouts
> (last mount created), ovl cannot clear this dir when we
> removing it, which may lead to rmdir fail or temp file left
> in workdir.
>
> Simple reproducer:
> mkdir lower upper work merge
> mkdir -p lower/dir
> touch lower/dir/a
> mount -t overlay overlay -olowerdir=lower,upperdir=upper,\
> workdir=work merge
> rm merge/dir/a
> umount merge
> rm -rf lower/*
> touch lower/dir (*)
> mount -t overlay overlay -olowerdir=lower,upperdir=upper,\
> workdir=work merge
> rm -rf merge/dir
>
> Syslog dump:
> overlayfs: cleanup of 'work/#7' failed (-39)
>
> (*): if we are not creat this file, the result is different:
> rm: cannot remove "dir/": Directory not empty
>
> This patch add explicitly check of OVL_XATTR_ORIGIN, use
> (merge || origin) to indicate the dir may have whiteouts.
> Finally, check and clean up the dir when deleting it.
>
> Signed-off-by: zhangyi (F) <yi.zhang@xxxxxxxxxx>
>
> ---
> V3:
> - use origin instead of impure flag
> - add check in ovl_rename()
>
> V2:
> - fix comment in ovl_remove_and_whiteout()
> - post reproducer to xfstest
>
> ---
Sorry, completely missed the part where you don't prevent
exposing of whiteouts in readdir.
I posted a patch that can either be picked by itself of squashed with this one.
> fs/overlayfs/dir.c | 20 ++++++++++++++++----
> fs/overlayfs/overlayfs.h | 1 +
> fs/overlayfs/util.c | 13 +++++++++++++
> 3 files changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
> index a63a716..cbad42f 100644
> --- a/fs/overlayfs/dir.c
> +++ b/fs/overlayfs/dir.c
> @@ -178,6 +178,14 @@ static bool ovl_type_origin(struct dentry *dentry)
> return OVL_TYPE_ORIGIN(ovl_path_type(dentry));
> }
>
> +static bool ovl_is_origin(struct dentry *dentry)
> +{
> + if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
> + return false;
> +
I am not so sure that !OVL_TYPE_UPPER should be skipped.
in case of ovl_rename() new can be lower with origin and with
whiteouts, that that lower was once used as upper.
Please extend your xfstest to check that whiteouts are not
exposed also when a former upper layer with origin is
used in a mount as a lower layer.
Thanks,
Amir.
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