def commit(self, t_params=None):
"""
commit snapshot to backing file;
"""
error_context.context("commit snapshot to backingfile", logging.info)
params = self.params.object_params(self.tag)
if t_params:
params.update(t_params)
cache_mode = params.get("cache_mode")
return QemuImg.commit(self, params, cache_mode)