On Tue, Jul 31, 2018 at 12:37 PM, zhangyi (F) <yi.zhang@xxxxxxxxxx> wrote:
> Redirect dir feature is backward incompatible because old kernel (which
> not support this feature) may corrupt the merge relationship between
> directories when change the directory which have redirect xattr.
>
> This patch check and set the upper layer's redirect dir feature when
> kernel set redirect xattr to directory in the upper layer.
>
> Signed-off-by: zhangyi (F) <yi.zhang@xxxxxxxxxx>
> ---
> fs/overlayfs/dir.c | 11 +++++++++++
> fs/overlayfs/overlayfs.h | 5 ++++-
> 2 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
> index f480b1a2cd2e..238999e5f47b 100644
> --- a/fs/overlayfs/dir.c
> +++ b/fs/overlayfs/dir.c
> @@ -969,6 +969,7 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
> bool is_dir = d_is_dir(old);
> bool new_is_dir = d_is_dir(new);
> bool samedir = olddir == newdir;
> + struct ovl_fs* ofs = old->d_sb->s_fs_info;
> struct dentry *opaquedir = NULL;
> const struct cred *old_cred = NULL;
> LIST_HEAD(list);
> @@ -1061,6 +1062,16 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
> }
> }
>
> + if ((is_dir && ovl_type_merge_or_lower(old)) ||
> + (!overwrite && new_is_dir && ovl_type_merge_or_lower(new))) {
> + /*
> + * Set redirect dir feature to the upper root dir if this
> + * feature doesn't exist.
> + */
> + if (!ovl_has_feature_redirect_dir(ofs->upper_layer))
> + err = ovl_set_feature_redirect_dir(ofs);
> + }
> +
Please just place a call to ovl_set_feature_redirect_dir(ofs)
inside ovl_set_redirect(). There is no need to check all those
conditions.
Also, there is no need to check ovl_has_feature_redirect_dir()
as ovl_set_feature() already checks for existing bit.
Thanks,
Amir.
> trap = lock_rename(new_upperdir, old_upperdir);
>
> olddentry = lookup_one_len(old->d_name.name, old_upperdir,
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index d6231acc660a..7ed8ed49266f 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -62,7 +62,8 @@ struct ovl_d_feature {
> #define OVL_FEATURE_RO_COMPAT_SUPP (0)
> #define OVL_FEATURE_RO_COMPAT_UNKNOWN (~OVL_FEATURE_RO_COMPAT_SUPP)
>
> -#define OVL_FEATURE_INCOMPAT_SUPP (0)
> +#define OVL_FEATURE_INCOMPAT_REDIRECT_DIR (1 << 0)
> +#define OVL_FEATURE_INCOMPAT_SUPP (OVL_FEATURE_INCOMPAT_REDIRECT_DIR)
> #define OVL_FEATURE_INCOMPAT_UNKNOWN (~OVL_FEATURE_INCOMPAT_SUPP)
>
> static inline bool ovl_has_unknown_compat_features(struct ovl_layer *layer)
> @@ -129,6 +130,8 @@ static inline int ovl_set_feature_##name(struct ovl_fs *ofs) \
> OVL_FEATURE_INCOMPAT_##flagname); \
> } \
>
> +OVL_FEATURE_INCOMPAT_FUNCS(redirect_dir, REDIRECT_DIR)
> +
> /*
> * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
> * where:
> --
> 2.13.6
>
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