def create_image(self, prepare_template, base, size, *args, **kwargs):
        def encrypt_lvm_image():
            dmcrypt.create_volume(self.path.rpartition('/')[2],
                                  self.lv_path,
                                  CONF.ephemeral_storage_encryption.cipher,
                                  CONF.ephemeral_storage_encryption.key_size,
                                  key)

        filename = self._get_lock_name(base)

        @utils.synchronized(filename, external=True, lock_path=self.lock_path)
        def create_lvm_image(base, size):
            base_size = disk.get_disk_size(base)
            self.verify_base_size(base, size, base_size=base_size)
            resize = size > base_size
            size = size if resize else base_size
            lvm.create_volume(self.vg, self.lv,
                                         size, sparse=self.sparse)
            if self.ephemeral_key_uuid is not None:
                encrypt_lvm_image()
            # NOTE: by calling convert_image_unsafe here we're
            # telling qemu-img convert to do format detection on the input,
            # because we don't know what the format is. For example,
            # we might have downloaded a qcow2 image, or created an
            # ephemeral filesystem locally, we just don't know here. Having
            # audited this, all current sources have been sanity checked,
            # either because they're locally generated, or because they have
            # come from images.fetch_to_raw. However, this is major code smell.
            images.convert_image_unsafe(base, self.path, self.driver_format,
                                        run_as_root=True)
            if resize:
                disk.resize2fs(self.path, run_as_root=True)

        generated = 'ephemeral_size' in kwargs
        if self.ephemeral_key_uuid is not None:
            if 'context' in kwargs:
                try:
                    # NOTE(dgenin): Key manager corresponding to the
                    # specific backend catches and reraises an
                    # an exception if key retrieval fails.
                    key = self.key_manager.get_key(kwargs['context'],
                            self.ephemeral_key_uuid).get_encoded()
                except Exception:
                    with excutils.save_and_reraise_exception():
                        LOG.error(_LE("Failed to retrieve ephemeral encryption"
                                      " key"))
            else:
                raise exception.NovaException(
                    _("Instance disk to be encrypted but no context provided"))
        # Generate images with specified size right on volume
        if generated and size:
            lvm.create_volume(self.vg, self.lv,
                                         size, sparse=self.sparse)
            with self.remove_volume_on_error(self.path):
                if self.ephemeral_key_uuid is not None:
                    encrypt_lvm_image()
                prepare_template(target=self.path, *args, **kwargs)
        else:
            if not os.path.exists(base):
                prepare_template(target=base, max_size=size, *args, **kwargs)
            with self.remove_volume_on_error(self.path):
                create_lvm_image(base, size)