| title | description | keywords | ms.date | ||
|---|---|---|---|---|---|
Request Ownership |
Request Ownership |
|
04/20/2017 |
When the I/O manager sends an I/O request to a framework-based driver, the framework intercepts the request and creates a framework request object. The framework "owns" the request object, because only the framework can access the request and perform operations on the object.
After the framework creates a request object, it places the object in one of the driver's I/O queues. The framework continues to own the request object until it removes the request from the queue and delivers it to the driver.
After the driver receives the request object, it owns the request. The driver can access the request object through a handle and perform operations on the object. While the driver owns the request object it can requeue, complete, cancel, or forward the request, after which it no longer owns the request object and cannot access it.
As ownership of a request object passes between a driver and the framework, the object handle's value does not change. For example, if a driver receives a request from an I/O queue, requeues it to a different queue, and then receives the request again, the handle's value will not change. Likewise, if a driver forwards a request to an I/O target and later receives notification that the I/O target completed the request, the driver's notification callback function receives the same handle value that the driver supplied to the I/O target.