ecryptfs_interpose
rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);