Filter Device Object Attached to a File System
Note
For optimal reliability and performance, use file system minifilter drivers with Filter Manager support instead of legacy file system filter drivers. To port your legacy driver to a minifilter driver, see Guidelines for Porting Legacy Filter Drivers.
To filter an entire file system, a legacy file system filter driver creates a filter device object and attaches it above a file system driver's CDO in the global file system queue.
Types of I/O Requests That Are Sent to a File System
A filter device object that is attached above a file system can generally expect to receive the following types of I/O requests:
If the file system supports opening handles to its control device object, filters can expect to see the following types of I/O requests as well:
File system filter device objects attached to file systems must pass all unrecognized or unwanted IRPs to the next-lower driver on the driver stack by default.
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