On 2018/1/4 3:56, Amir Goldstein Wrote:
> For a merge dir that was copied up before v4.12 or that was hand crafted
> offline (e.g. mkdir {upper/lower}/dir), upper dir does not contain the
> 'trusted.overlay.origin' xattr. In that case, stat(2) on the merge dir
> returns the lower dir st_ino, but getdents(2) returns the upper dir d_ino.
>
> After this change, on merge dir lookup, missing origin xattr on upper
> dir will be fixed and 'impure' xattr will be fixed on parent of the legacy
> merge dir.
>
> Suggested-by: zhangyi (F) <yi.zhang@xxxxxxxxxx>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
>
> Zhangyi,
>
> A slightly differnt patch. This time with ovl_want_write()
> and using different helpers.
>
> Please re-review and test.
>
Looks good to me.
Reviewed-by: zhangyi (F) <yi.zhang@xxxxxxxxxx>
> Thanks,
> Amir.
>
> fs/overlayfs/copy_up.c | 4 ++--
> fs/overlayfs/namei.c | 33 +++++++++++++++++++++++++++++++++
> fs/overlayfs/overlayfs.h | 2 ++
> 3 files changed, 37 insertions(+), 2 deletions(-)
>
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index eb3b8d39fb61..206ececd5ae7 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -288,8 +288,8 @@ struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper)
> return fh;
> }
>
> -static int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
> - struct dentry *upper)
> +int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
> + struct dentry *upper)
> {
> const struct ovl_fh *fh = NULL;
> int err;
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index 9cf15463754c..71db9a966d88 100644
> --- a/fs/overlayfs/namei.c
> +++ b/fs/overlayfs/namei.c
> @@ -584,6 +584,27 @@ static int ovl_find_layer(struct ovl_fs *ofs, struct ovl_path *path)
> return i;
> }
>
> +/* Fix missing 'origin' xattr */
> +static int ovl_fix_origin(struct dentry *dentry, struct dentry *lower,
> + struct dentry *upper)
> +{
> + int err;
> +
> + if (ovl_check_origin_xattr(upper))
> + return 0;
> +
> + err = ovl_want_write(dentry);
> + if (err)
> + return err;
> +
> + err = ovl_set_origin(dentry, lower, upper);
> + if (!err)
> + err = ovl_set_impure(dentry->d_parent, upper->d_parent);
> +
> + ovl_drop_write(dentry);
> + return err;
> +}
> +
> struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
> unsigned int flags)
> {
> @@ -674,6 +695,18 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
> if (!this)
> continue;
>
> + /*
> + * If no origin fh is stored in upper of a merge dir, store fh
> + * of lower dir and set upper parent "impure".
> + */
> + if (upperdentry && !ctr && !ofs->noxattr) {
> + err = ovl_fix_origin(dentry, this, upperdentry);
> + if (err) {
> + dput(this);
> + goto out_put;
> + }
> + }
> +
> stack[ctr].dentry = this;
> stack[ctr].layer = lower.layer;
> ctr++;
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index b489099ccd49..d1cfa69c98b5 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -322,3 +322,5 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags);
> int ovl_copy_xattr(struct dentry *old, struct dentry *new);
> int ovl_set_attr(struct dentry *upper, struct kstat *stat);
> struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper);
> +int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
> + struct dentry *upper);
>
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