/*
* StepLowMemRetry
*
* During extreme low-memory stress, this function retries
* a packet in small one-page chunks, sent serially.
*
* Returns TRUE iff the packet is done.
*/
BOOLEAN NTAPI StepLowMemRetry(PTRANSFER_PACKET Pkt)
{
BOOLEAN packetDone;
if (Pkt->LowMemRetry_remainingBufLen == 0){
packetDone = TRUE;
}
else {
ULONG thisChunkLen;
ULONG bytesToNextPageBoundary;
/*
* Make sure the little chunk we send is <= a page length
* AND that it does not cross any page boundaries.
*/
bytesToNextPageBoundary = PAGE_SIZE-(ULONG)((ULONG_PTR)Pkt->LowMemRetry_remainingBufPtr%PAGE_SIZE);
thisChunkLen = MIN(Pkt->LowMemRetry_remainingBufLen, bytesToNextPageBoundary);
/*
* Set up the transfer packet for the new little chunk.
* This will reset numRetries so that we retry each chunk as required.
*/
SetupReadWriteTransferPacket(Pkt,
Pkt->LowMemRetry_remainingBufPtr,
thisChunkLen,
Pkt->LowMemRetry_nextChunkTargetLocation,
Pkt->OriginalIrp);
Pkt->LowMemRetry_remainingBufPtr += thisChunkLen;
Pkt->LowMemRetry_remainingBufLen -= thisChunkLen;
Pkt->LowMemRetry_nextChunkTargetLocation.QuadPart += thisChunkLen;
SubmitTransferPacket(Pkt);
packetDone = FALSE;
}
return packetDone;
}
/*
* StepLowMemRetry
*
* During extreme low-memory stress, this function retries
* a packet in small one-page chunks, sent serially.
*
* Returns TRUE iff the packet is done.
*/
BOOLEAN StepLowMemRetry(PTRANSFER_PACKET Pkt)
{
BOOLEAN packetDone;
if (Pkt->LowMemRetry_remainingBufLen == 0){
packetDone = TRUE;
}
else {
ULONG thisChunkLen;
if (Pkt->DriverUsesStartIO)
{
/*
* Need the fdoData for the HwMaxXferLen
*/
PFUNCTIONAL_DEVICE_EXTENSION fdoExt = Pkt->Fdo->DeviceExtension;
PCLASS_PRIVATE_FDO_DATA fdoData = fdoExt->PrivateFdoData;
/*
* Need the adapterDesc to limit transfers based on byte count
*/
PCOMMON_DEVICE_EXTENSION commonExtension = Pkt->Fdo->DeviceExtension;
PSTORAGE_ADAPTER_DESCRIPTOR adapterDesc = commonExtension->PartitionZeroExtension->AdapterDescriptor;
ULONG hwMaxXferLen;
/*
* special case: StartIO-based writing must stay serialized for performance
* and proper operations (i.e. sequential writing mode). If need more than
* one transfer to perform this operation, and it's a StartIO-based driver
* (such as CDROM), then just use a single packet and use the retry logic
* that's already built-in to the packet engine. Note that low-mem retry
* cannot be used directly because some write methods do not work if the
* writes are only PAGE_SIZE (i.e. packet writing may corrupt data).
*/
NT_ASSERT(!Pkt->InLowMemRetry);
/*
* We precomputed fdoData->HwMaxXferLen using (MaximumPhysicalPages-1).
* If the buffer is page-aligned, that's one less page crossing so we can add the page back in.
* Note: adapters that return MaximumPhysicalPages=0x10 depend on this to
* transfer aligned 64K requests in one piece.
* Also note: make sure adding PAGE_SIZE back in doesn't wrap to zero.
*/
if (((ULONG_PTR)(Pkt->LowMemRetry_remainingBufPtr) & (PAGE_SIZE-1)) || (fdoData->HwMaxXferLen > 0xffffffff-PAGE_SIZE)){
hwMaxXferLen = fdoData->HwMaxXferLen;
}
else {
NT_ASSERT((PAGE_SIZE%fdoExt->DiskGeometry.BytesPerSector) == 0);
hwMaxXferLen = min(fdoData->HwMaxXferLen+PAGE_SIZE, adapterDesc->MaximumTransferLength);
}
thisChunkLen = MIN(Pkt->LowMemRetry_remainingBufLen, hwMaxXferLen);
}
else {
/*
* Make sure the little chunk we send is <= a page length
* AND that it does not cross any page boundaries.
*/
ULONG bytesToNextPageBoundary;
bytesToNextPageBoundary = PAGE_SIZE-(ULONG)((ULONG_PTR)Pkt->LowMemRetry_remainingBufPtr%PAGE_SIZE);
thisChunkLen = MIN(Pkt->LowMemRetry_remainingBufLen, bytesToNextPageBoundary);
NT_ASSERT(Pkt->InLowMemRetry);
}
/*
* Set up the transfer packet for the new little chunk.
* This will reset numRetries so that we retry each chunk as required.
*/
SetupReadWriteTransferPacket(Pkt,
Pkt->LowMemRetry_remainingBufPtr,
thisChunkLen,
Pkt->LowMemRetry_nextChunkTargetLocation,
Pkt->OriginalIrp);
Pkt->LowMemRetry_remainingBufPtr += thisChunkLen;
Pkt->LowMemRetry_remainingBufLen -= thisChunkLen;
Pkt->LowMemRetry_nextChunkTargetLocation.QuadPart += thisChunkLen;
//
// When running in low-memory stress, always use a partial MDL.
// This allows lower drivers to potentially map a smaller buffer.
//
Pkt->UsePartialMdl = TRUE;
TransferPacketQueueRetryDpc(Pkt);
packetDone = FALSE;
}
return packetDone;
}
