ExExtendZone

ExExtendZone

NTSTATUS
ExExtendZone(
IN PZONE_HEADER Zone,
IN PVOID Segment,
IN ULONG SegmentSize
);

ExExtendZone extends a zone by adding another segment’s worth of blocks to the zone.

Parameters

Zone

Points to the address of a zone header to be extended.

Segment

Points to a segment of storage. The base address of the segment must be aligned on an 8-byte boundary.

SegmentSize

Is the size in bytes of Segment.

Return Value

ExExtendZone returns one of the following:

Status	Meaning
STATUS_UNSUCCESSFUL	Segment was not aligned on an 8-byte boundary or a block size was larger than SegmentSize.
STATUS_SUCCESS	The zone was successfully extended.

Comments

When a zone has no free blocks, additional temporary memory should be allocated with ExAllocatePool, rather than ExExtendZone or ExInterlockedExtendZone. Such a temporary allocation can be released with ExFreePool when the original zone has free entries again.

ExExtendZone allocates memory that remains allocated to its caller until the machine is rebooted. Consequently, ExExtendZone should not be called every time a call to ExIsFullZone returns TRUE. Call ExExtendZone only for a very heavy I/O demand situation when neither the original zone’s entries are being released nor the temporary memory allocated with ExAllocatePool.

The first ZONE_SEGMENT_HEADER-sized portion of the segment is used by the zone allocator. The remainder of the segment is divided into fixed-size blocks, as specified by BlockSize in the original call to ExInitializeZone, and added to the zone.

Callers of ExExtendZone must be running at IRQL <= DISPATCH_LEVEL.