Stackable design of filing systems constructs sophisticated services from multiple, independently developed layers. This approach has been advocated to address development problems from code re-use, to extensibility, to version management. Individual layers of such a system often need to cache data to improve performance or provide desired functionality. When access to different layers is allowed, cache incoherencies can occur. Without a cache coherence solution, layer designers must either

more »

... rict layer access and flexibility or compromise the layered structure to avoid potential data corruption. The value of modular designs such as stacking can be questioned without a suitable solution to this problem. This paper presents a general cache coherence architecture for stackable filing, including a standard approach to data identification as a key component to layered coherence protocols. We also present a detailed performance analysis of one implementation of stack cache-coherence, which suggests that very low overheads can be achieved in practice.