Method and apparatus for dynamically unloading file system filters

摘要

The invention provides a system and method for dynamically unloading file system filters in a stacked-call-back model where filters are stacked one on top of the other to form a filter stack. A filter manager keeps track of the progress of each I/O operation and calls each filter in turn with the filter returning after it has completed processing the given operation. The filter manager dynamically unloads a filter (or an instance of a filter) that is positioned at any position in the filter stack in a reasonable amount of time while I/O operations are actively being processed. The filter/filter instance can be unloaded with outstanding I/O operations on the filter either hosted by the filter or pended by other filters. I/O operations are canceled, completed or drained in order to unload the filter or filter instance. A filter may veto the unloading of the filter.