1. A method comprising: representing a directory structure of a file system using a plurality of chunks in a content-addressable storage system, the directory structure comprising a set of objects arranged in an object hierarchy, wherein the set of objects includes a particular directory that has, within the object hierarchy, a set of child objects; the plurality of chunks comprising: a directory object chunk for the particular directory; a particular set of child object chunks, wherein the particular set of child object chunks are object chunks for each child object in the set of child objects; and at least one hash set chunk that includes hash values for object chunks in the particular set of child object chunks; wherein the directory object chunk includes a hash value for a primary hash set chunk of the at least one hash set chunk.