1. A method, comprising: assigning two or more storage controllers of a storage system to an atomic storage request, each of the two or more storage controllers assigned to implement respective sub-requests of the atomic storage request based on associations between addresses of the atomic storage request and logical address spaces managed by respective storage controllers of the storage system; generating completion metadata for the atomic storage request, the completion metadata comprising one or more of: a number of storage controllers assigned to the atomic storage request and an identifier of each of the assigned storage controllers; and configuring each storage controller of the assigned storage controllers to store the completion metadata generated for the atomic storage request in response to completing implementation of the respective sub-requests assigned to the storage controller.