A file system interface receives, from one or more clients, file system operations over a network. In response to receiving a file system operation for a file, a file-object manager calls an object storage interface to store, via an application-level network protocol, a log object indicating the file system operation into a file system log in the object storage system and creates or updates a file object in a file object construction buffer in volatile system memory. To evict the file object, the file-object manager calls the object storage interface to store the file object into a file object store in the object storage system. The file-object manager does not have access to local persistent storage. After power failure, the file-object manager calls the object storage interface to retrieve log objects from the file system log and replays file system operations to restore file objects in the volatile system memory.