1. A method comprising: maintaining a cache of child-to-parent mappings; wherein each child-to-parent mapping corresponds to a particular chunk in a hierarchy of chunks stored in a content-addressable storage system, wherein the content-addressable storage system allows retrieval of items based on data that is generated from content of the items, and maps the particular chunk to a parent chunk in the hierarchy of chunks; wherein the hierarchy of chunks includes a first root chunk associated with a first file system volume; in response to a change to the file system volume that causes associating a new root chunk with the first file system volume, updating the cache by adding one or more first child-to-parent mappings based on traversing at least a portion of a current file system hierarchy from the new root chunk, and removing one or more second child-to-parent mappings based on traversing at least a portion of a prior file system hierarchy from the first root chunk.