On Tue, Apr 17, 2018 at 5:42 AM, Chengguang Xu <cgxu519@xxxxxxx> wrote:
> Introduce __ovl_path_lower() to handle lowerstack related things
> and refactor ovl_dentry_lower()/ovl_layer_lower() based on it.
>
> Signed-off-by: Chengguang Xu <cgxu519@xxxxxxx>
> ---
> fs/overlayfs/overlayfs.h | 1 +
> fs/overlayfs/util.c | 35 +++++++++++++++++++++++++++++++----
> 2 files changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index e0b7de7..abb5cf4 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -215,6 +215,7 @@ static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
> enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
> struct dentry *ovl_dentry_upper(struct dentry *dentry);
> struct dentry *ovl_dentry_lower(struct dentry *dentry);
> +struct vfsmount *ovl_mnt_lower(struct dentry *dentry);
> struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
> struct dentry *ovl_dentry_real(struct dentry *dentry);
> struct dentry *ovl_i_dentry_upper(struct inode *inode);
> diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> index 6f10780..a3459e6 100644
> --- a/fs/overlayfs/util.c
> +++ b/fs/overlayfs/util.c
> @@ -157,8 +157,8 @@ void ovl_path_lower(struct dentry *dentry, struct path *path)
> struct ovl_entry *oe = dentry->d_fsdata;
>
> if (oe->numlower) {
> - path->mnt = oe->lowerstack[0].layer->mnt;
> - path->dentry = oe->lowerstack[0].dentry;
> + path->mnt = ovl_mnt_lower(dentry);
> + path->dentry = ovl_dentry_lower(dentry);
> } else {
> *path = (struct path) { };
> }
> @@ -181,18 +181,45 @@ struct dentry *ovl_dentry_upper(struct dentry *dentry)
> return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
> }
>
> +struct ovl_path *__ovl_path_lower(struct ovl_entry *oe, int layer)
The name is going to be confused with ovl_path_lower, but
I don't have a better suggestion.
For the @layer arg I propose two options.
Either @idx for layer index, like other helpers
Or simply @i for lower layer index, because it doesn't make much sense
to request idx=0 (upper) from a helper called xxx_lower().
If you choose to stay with @idx convention, you should add
if (WARN_ON(idx < 1)) return NULL;
> +{
> + if (layer > oe->numlower)
> + return NULL;
> +
> + return &oe->lowerstack[layer - 1];
> +}
> +
> +struct vfsmount *ovl_mnt_lower(struct dentry *dentry)
> +{
> + struct ovl_entry *oe = dentry->d_fsdata;
> + struct ovl_path *path = __ovl_path_lower(oe, 1);
> +
> + if (path)
> + return path->layer->mnt;
> + else
> + return NULL;
> +}
> +
> struct dentry *ovl_dentry_lower(struct dentry *dentry)
> {
> struct ovl_entry *oe = dentry->d_fsdata;
> + struct ovl_path *path = __ovl_path_lower(oe, 1);
>
> - return oe->numlower ? oe->lowerstack[0].dentry : NULL;
> + if (path)
> + return path->dentry;
> + else
> + return NULL;
> }
>
> struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
> {
> struct ovl_entry *oe = dentry->d_fsdata;
> + struct ovl_path *path = __ovl_path_lower(oe, 1);
>
> - return oe->numlower ? oe->lowerstack[0].layer : NULL;
> + if (path)
> + return path->layer;
> + else
> + return NULL;
> }
>
I am not yet convinced that this re-factoring is needed,
but if you keep it, please preserve the style:
struct ovl_path *op = __ovl_path_lower(OVL_E(dentry), 1);
return op ? op->layer : NULL;
Thanks,
Amir.
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