ovl: add ovl_upper_mnt_userns() wrapper

Add a tiny wrapper to retrieve the upper mount's idmapping. Have it
return the initial idmapping until we have prepared and converted all
places to take the relevant idmapping into account. Then we can switch
on idmapped layer support by having ovl_upper_mnt_userns() return the
upper mount's idmapping.

Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 63efee554f69a7c1e862650d8f7b388576fda2cd..61b40d1268c89bd4bea15d5f0b8372247426d68c 100644 (file)
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -90,6 +90,11 @@ static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
        return ofs->layers[0].mnt;
 }
 
+static inline struct user_namespace *ovl_upper_mnt_userns(struct ovl_fs *ofs)
+{
+       return &init_user_ns;
+}
+
 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
 {
        return (struct ovl_fs *)sb->s_fs_info;