Transaction-Based Process Crash Recovery of File System Namespace Modules

In this paper, we describe the emerging concept of namespace modules: operating system components that are responsible for constructing a hierarchical file system namespace based on one or more individual underlying file objects. We show that the likely presence of software bugs in such modules calls for the ability to recover from crashes, but that the current state of the art falls short of the desired behavior. We then introduce a crash recovery solution that is based on transactions, and detail the requirements for a system to implement this solution. We apply our solution to two different use cases: the primary namespace module for a storage stack, and an extension module that exposes the contents of scientific data files. Our evaluation shows that the transaction system has low overhead and significantly adds to the robustness of the namespace modules.