The server provides:
Open: An Open of a DataFile.
OutputBufferSize: The maximum number of bytes to return in OutputBuffer.
On completion, the object store MUST return:
Status: An NTSTATUS code that specifies the result.
BytesReturned: The number of bytes returned in OutputBuffer.
Support for this operation is optional. If the object store does not implement this functionality, the operation MUST be failed with STATUS_INVALID_DEVICE_REQUEST.<85>
Pseudocode for the operation is as follows:
If OutputBufferSize is less than sizeof(FILE_QUERY_SPARING_BUFFER), the operation MUST be failed with STATUS_INVALID_PARAMETER.
The object store MUST populate the fields of OutputBuffer as follows:
OutputBuffer.SparingUnitBytes set to Open.File.Volume.SparingUnitBytes.
OutputBuffer.SoftwareSparing set to Open.File.Volume.SoftwareSparing.
OutputBuffer.TotalSpareBlocks set to Open.File.Volume.TotalSpareBlocks.
OutputBuffer.FreeSpareBlocks set to Open.File.Volume.FreeSpareBlocks.
Upon successful completion of the operation, the object store MUST return:
BytesReturned set to sizeof(: FILE_QUERY_SPARING_BUFFER).
Status set to STATUS_SUCCESS.