Pending IO in MiniFilter

Pending IO in PreOperation Callback

 

n  FltCompletePendedPreOperation()

n  Must call this to restart processing of IO pended in the preOperation callback

n  Filter may:

n  Complete operation

n  Request postOperation callback through the FLT_PREOP_CALLBACK_STATUS parameter

n  Typically called from a worker thread

 

n  FltQueueDeferredIoWorkItem()

n  Queue operation to worker thread for continued processing

n  Can fail if this operation is not safe to post �C i.e., this is paging IO or top-level IRP is already set on this thread

n  Can fail if this Instance is in the process of being torndown

 

 

 

 

Pending IO in PostOperation Callback

n  FltDoCompletionProcessingWhenSafe()

n  Can fail if it is not safe to post

n  Not safe to post Paging IO’s

n  Synchronize operation if you cannot handle this failure

n  Tells filter the appropriate postOperation callback status to return

n  Will only post operation if currently at DPC IRQL

n  Will continue completion processing when WorkerRoutine has completed

 

 

n  FltQueueDeferredIoWorkItem()

n  Works just like in preOperation

n  Will always queue work to worker thread if it is safe to do so

n  If successfully queues work, return FLT_POSTOP_MORE_PROCESSING_REQUIRED

n  FltCompletePendedPostOperation()

n  Must call this to restart processing of IO pended in the postOperation callback