File system primitive allowing reprocessing of i/o requests by multiple

Abstract

I/O systems of computers typically utilize multiple layered drivers to process I/O requests. I/O requests are passed from one driver to another in a defined sequence with each driver performing its processing in turn. The present invention provides a system and method for interrupting the normal sequence of processing and for allowing drivers that would not normally process an I/O request to intervene and assume control for processing the I/O request. The system and method provides a flexible and extensible way to define special types of files or directories that require special processing by a particular driver. The present invention adds a 'reparse point' attribute to a file or directory. The reparse point attribute preferably contains a tag which identifies a particular driver as the owner of the reparse point and a data value which can be used by the owner driver to store any information necessary or useful in processing an I/O request. When a driver encounters a reparse point attribute, processing is interrupted and the tag and value of the reparse point are extracted from the attribute. The tag and value are then passed to the next higher level driver in the layered driver system until one driver recognizes itself as the owner of the reparse point. That driver then assumes responsibility for completing the I/O request. The owner of the reparse point may process the entire I/O requests itself, or may make further use of other drivers by passing other I/O requests to the drivers.