Implementation of Concurrent Access to File Systems in USB Devices

The combination of a removable storage device with a communication channel and a computation node is a common architectural theme in many system-on-chip (SOC) designs. The systems in which many of these devices are placed produce or consume digital media content from their removable storage devices, which are formatted with industrystandard file systems. When the communication channel is USB, the systems exchange this media content with a host via the USB Mass Storage Device Class (MSDC) specification. It is useful to allow a connected host access to the removable storage device concurrently with the operation of the computation node, the embedded SOC processor. There are difficulties in supporting such concurrency. This paper presents a method of achieving concurrency based on serialization of access to file system management structures (metadata).