Provided a computer program product, system, and method for notifying a cache file system of changes to files in a source file system served from the cache file system. The source node establishes a local share of a cache file system at the cache node. The cache file system at the cache node comprises a local share of a source file system at the source node. In response to modifying a source file in the source file system, a source control file for the source file in the local share of the cache file system is updated to indicate the source file is modified. In response to updating the source control file, sending, to the cache node, indication of the updating of the source control file to cause the cache node to update a cache control file to indicate a change to the source file at the source node.