dev/raidframe/rf_parityloggingdags.c

/*	$OpenBSD: rf_parityloggingdags.c,v 1.4 2002/12/16 07:01:04 tdeval Exp $	*/
/*	$NetBSD: rf_parityloggingdags.c,v 1.4 2000/01/07 03:41:04 oster Exp $	*/

/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: William V. Courtright II
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

#include "rf_archs.h"

#if	RF_INCLUDE_PARITYLOGGING > 0

/*
 * DAGs specific to parity logging are created here.
 */

#include "rf_types.h"
#include "rf_raid.h"
#include "rf_dag.h"
#include "rf_dagutils.h"
#include "rf_dagfuncs.h"
#include "rf_debugMem.h"
#include "rf_paritylog.h"
#include "rf_memchunk.h"
#include "rf_general.h"

#include "rf_parityloggingdags.h"

/*****************************************************************************
 *
 * Creates a DAG to perform a large-write operation:
 *
 *         / Rod \     / Wnd \
 * H -- NIL- Rod - NIL - Wnd ------ NIL - T
 *         \ Rod /     \ Xor - Lpo /
 *
 * The writes are not done until the reads complete because if they were done
 * in parallel, a failure on one of the reads could leave the parity in an
 * inconsistent state, so that the retry with a new DAG would produce
 * erroneous parity.
 *
 * Note:  This DAG has the nasty property that none of the buffers allocated
 *        for reading old data can be freed until the XOR node fires.
 *        Need to fix this.
 *
 * The last two arguments are the number of faults tolerated, and function
 * for the redundancy calculation. The undo for the redundancy calc is assumed
 * to be null.
 *
 *****************************************************************************/

void
rf_CommonCreateParityLoggingLargeWriteDAG(RF_Raid_t * raidPtr,
    RF_AccessStripeMap_t *asmap, RF_DagHeader_t *dag_h, void *bp,
    RF_RaidAccessFlags_t flags, RF_AllocListElem_t *allocList, int nfaults,
    int (*redFunc) (RF_DagNode_t *))
{
	RF_DagNode_t *nodes, *wndNodes, *rodNodes = NULL, *syncNode, *xorNode;
	RF_DagNode_t *lpoNode, *blockNode, *unblockNode, *termNode;
	int nWndNodes, nRodNodes, i;
	RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
	RF_AccessStripeMapHeader_t *new_asm_h[2];
	int nodeNum, asmNum;
	RF_ReconUnitNum_t which_ru;
	char *sosBuffer, *eosBuffer;
	RF_PhysDiskAddr_t *pda;
	RF_StripeNum_t parityStripeID =
	    rf_RaidAddressToParityStripeID(&(raidPtr->Layout),
	     asmap->raidAddress, &which_ru);

	if (rf_dagDebug)
		printf("[Creating parity-logging large-write DAG]\n");
	RF_ASSERT(nfaults == 1); /* This arch only single fault tolerant. */
	dag_h->creator = "ParityLoggingLargeWriteDAG";

	/* Alloc the Wnd nodes, the xor node, and the Lpo node. */
	nWndNodes = asmap->numStripeUnitsAccessed;
	RF_CallocAndAdd(nodes, nWndNodes + 6, sizeof(RF_DagNode_t),
	    (RF_DagNode_t *), allocList);
	i = 0;
	wndNodes = &nodes[i];
	i += nWndNodes;
	xorNode = &nodes[i];
	i += 1;
	lpoNode = &nodes[i];
	i += 1;
	blockNode = &nodes[i];
	i += 1;
	syncNode = &nodes[i];
	i += 1;
	unblockNode = &nodes[i];
	i += 1;
	termNode = &nodes[i];
	i += 1;

	dag_h->numCommitNodes = nWndNodes + 1;
	dag_h->numCommits = 0;
	dag_h->numSuccedents = 1;

	rf_MapUnaccessedPortionOfStripe(raidPtr, layoutPtr, asmap, dag_h,
	    new_asm_h, &nRodNodes, &sosBuffer, &eosBuffer, allocList);
	if (nRodNodes > 0)
		RF_CallocAndAdd(rodNodes, nRodNodes, sizeof(RF_DagNode_t),
		    (RF_DagNode_t *), allocList);

	/* Begin node initialization. */
	rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc,
	    rf_NullNodeUndoFunc, NULL, nRodNodes + 1, 0, 0, 0, dag_h,
	    "Nil", allocList);
	rf_InitNode(unblockNode, rf_wait, RF_FALSE, rf_NullNodeFunc,
	    rf_NullNodeUndoFunc, NULL, 1, nWndNodes + 1, 0, 0, dag_h,
	    "Nil", allocList);
	rf_InitNode(syncNode, rf_wait, RF_FALSE, rf_NullNodeFunc,
	    rf_NullNodeUndoFunc, NULL, nWndNodes + 1, nRodNodes + 1,
	    0, 0, dag_h, "Nil", allocList);
	rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc,
	    rf_TerminateUndoFunc, NULL, 0, 1, 0, 0, dag_h, "Trm", allocList);

	/* Initialize the Rod nodes. */
	for (nodeNum = asmNum = 0; asmNum < 2; asmNum++) {
		if (new_asm_h[asmNum]) {
			pda = new_asm_h[asmNum]->stripeMap->physInfo;
			while (pda) {
				rf_InitNode(&rodNodes[nodeNum], rf_wait,
				    RF_FALSE, rf_DiskReadFunc,
				    rf_DiskReadUndoFunc, rf_GenericWakeupFunc,
				    1, 1, 4, 0, dag_h, "Rod", allocList);
				rodNodes[nodeNum].params[0].p = pda;
				rodNodes[nodeNum].params[1].p = pda->bufPtr;
				rodNodes[nodeNum].params[2].v = parityStripeID;
				rodNodes[nodeNum].params[3].v =
				    RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY,
				     0, 0, which_ru);
				nodeNum++;
				pda = pda->next;
			}
		}
	}
	RF_ASSERT(nodeNum == nRodNodes);

	/* Initialize the wnd nodes. */
	pda = asmap->physInfo;
	for (i = 0; i < nWndNodes; i++) {
		rf_InitNode(&wndNodes[i], rf_wait, RF_TRUE, rf_DiskWriteFunc,
		    rf_DiskWriteUndoFunc, rf_GenericWakeupFunc, 1, 1, 4, 0,
		    dag_h, "Wnd", allocList);
		RF_ASSERT(pda != NULL);
		wndNodes[i].params[0].p = pda;
		wndNodes[i].params[1].p = pda->bufPtr;
		wndNodes[i].params[2].v = parityStripeID;
		wndNodes[i].params[3].v =
		    RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, which_ru);
		pda = pda->next;
	}

	/* Initialize the redundancy node. */
	rf_InitNode(xorNode, rf_wait, RF_TRUE, redFunc, rf_NullNodeUndoFunc,
	    NULL, 1, 1, 2 * (nWndNodes + nRodNodes) + 1, 1, dag_h,
	    "Xr ", allocList);
	xorNode->flags |= RF_DAGNODE_FLAG_YIELD;
	for (i = 0; i < nWndNodes; i++) {
		/* pda */
		xorNode->params[2 * i + 0] = wndNodes[i].params[0];
		/* buf ptr */
		xorNode->params[2 * i + 1] = wndNodes[i].params[1];
	}
	for (i = 0; i < nRodNodes; i++) {
		xorNode->params[2 * (nWndNodes + i) + 0] =
		    rodNodes[i].params[0];	/* pda */
		xorNode->params[2 * (nWndNodes + i) + 1] =
		    rodNodes[i].params[1];	/* buf ptr */
	}
	/* Xor node needs to get at RAID information. */
	xorNode->params[2 * (nWndNodes + nRodNodes)].p = raidPtr;

	/*
	 * Look for an Rod node that reads a complete SU. If none, alloc a
	 * buffer to receive the parity info. Note that we can't use a new
	 * data buffer because it will not have gotten written when the xor
	 * occurs.
	 */
	for (i = 0; i < nRodNodes; i++)
		if (((RF_PhysDiskAddr_t *) rodNodes[i].params[0].p)
		    ->numSector == raidPtr->Layout.sectorsPerStripeUnit)
			break;
	if (i == nRodNodes) {
		RF_CallocAndAdd(xorNode->results[0], 1,
		    rf_RaidAddressToByte(raidPtr,
		     raidPtr->Layout.sectorsPerStripeUnit), (void *),
		    allocList);
	} else {
		xorNode->results[0] = rodNodes[i].params[1].p;
	}

	/* Initialize the Lpo node. */
	rf_InitNode(lpoNode, rf_wait, RF_FALSE, rf_ParityLogOverwriteFunc,
	    rf_ParityLogOverwriteUndoFunc, rf_GenericWakeupFunc, 1, 1, 2, 0,
	    dag_h, "Lpo", allocList);

	lpoNode->params[0].p = asmap->parityInfo;
	lpoNode->params[1].p = xorNode->results[0];
	/* parityInfo must describe entire parity unit. */
	RF_ASSERT(asmap->parityInfo->next == NULL);

	/* Connect nodes to form graph. */

	/* Connect dag header to block node. */
	RF_ASSERT(dag_h->numSuccedents == 1);
	RF_ASSERT(blockNode->numAntecedents == 0);
	dag_h->succedents[0] = blockNode;

	/* Connect the block node to the Rod nodes. */
	RF_ASSERT(blockNode->numSuccedents == nRodNodes + 1);
	for (i = 0; i < nRodNodes; i++) {
		RF_ASSERT(rodNodes[i].numAntecedents == 1);
		blockNode->succedents[i] = &rodNodes[i];
		rodNodes[i].antecedents[0] = blockNode;
		rodNodes[i].antType[0] = rf_control;
	}

	/* Connect the block node to the sync node. */
	/* necessary if nRodNodes == 0 */
	RF_ASSERT(syncNode->numAntecedents == nRodNodes + 1);
	blockNode->succedents[nRodNodes] = syncNode;
	syncNode->antecedents[0] = blockNode;
	syncNode->antType[0] = rf_control;

	/* Connect the Rod nodes to the syncNode. */
	for (i = 0; i < nRodNodes; i++) {
		rodNodes[i].succedents[0] = syncNode;
		syncNode->antecedents[1 + i] = &rodNodes[i];
		syncNode->antType[1 + i] = rf_control;
	}

	/* Connect the sync node to the xor node. */
	RF_ASSERT(syncNode->numSuccedents == nWndNodes + 1);
	RF_ASSERT(xorNode->numAntecedents == 1);
	syncNode->succedents[0] = xorNode;
	xorNode->antecedents[0] = syncNode;
	xorNode->antType[0] = rf_trueData;	/* Carry forward from sync. */

	/* Connect the sync node to the Wnd nodes. */
	for (i = 0; i < nWndNodes; i++) {
		RF_ASSERT(wndNodes->numAntecedents == 1);
		syncNode->succedents[1 + i] = &wndNodes[i];
		wndNodes[i].antecedents[0] = syncNode;
		wndNodes[i].antType[0] = rf_control;
	}

	/* Connect the xor node to the Lpo node. */
	RF_ASSERT(xorNode->numSuccedents == 1);
	RF_ASSERT(lpoNode->numAntecedents == 1);
	xorNode->succedents[0] = lpoNode;
	lpoNode->antecedents[0] = xorNode;
	lpoNode->antType[0] = rf_trueData;

	/* Connect the Wnd nodes to the unblock node. */
	RF_ASSERT(unblockNode->numAntecedents == nWndNodes + 1);
	for (i = 0; i < nWndNodes; i++) {
		RF_ASSERT(wndNodes->numSuccedents == 1);
		wndNodes[i].succedents[0] = unblockNode;
		unblockNode->antecedents[i] = &wndNodes[i];
		unblockNode->antType[i] = rf_control;
	}

	/* Connect the Lpo node to the unblock node. */
	RF_ASSERT(lpoNode->numSuccedents == 1);
	lpoNode->succedents[0] = unblockNode;
	unblockNode->antecedents[nWndNodes] = lpoNode;
	unblockNode->antType[nWndNodes] = rf_control;

	/* Connect unblock node to terminator. */
	RF_ASSERT(unblockNode->numSuccedents == 1);
	RF_ASSERT(termNode->numAntecedents == 1);
	RF_ASSERT(termNode->numSuccedents == 0);
	unblockNode->succedents[0] = termNode;
	termNode->antecedents[0] = unblockNode;
	termNode->antType[0] = rf_control;
}


/*****************************************************************************
 *
 * Creates a DAG to perform a small-write operation (either raid 5 or pq),
 * which is as follows:
 *
 *				       Header
 *				          |
 *				        Block
 *				    / |  ... \   \
 *				   /  |       \   \
 *				Rod  Rod      Rod  Rop
 *				 | \ /| \    / |  \/ |
 *				 |    |        |  /\ |
 *				Wnd  Wnd      Wnd   X
 *				 |    \       /     |
 *				 |     \     /      |
 *				  \     \   /      Lpo
 *				   \     \ /       /
 *				    +-> Unblock <-+
 *				          |
 *				          T
 *
 *
 * R = Read, W = Write, X = Xor, o = old, n = new, d = data, p = parity.
 * When the access spans a stripe unit boundary and is less than one SU in
 * size, there will be two Rop -- X -- Wnp branches. I call this the
 * "double-XOR" case.
 * The second output from each Rod node goes to the X node. In the double-XOR
 * case, there are exactly 2 Rod nodes, and each sends one output to one X
 * node.
 * There is one Rod -- Wnd -- T branch for each stripe unit being updated.
 *
 * The block and unblock nodes are unused. See comment above
 * CreateFaultFreeReadDAG.
 *
 * Note:  This DAG ignores all the optimizations related to making the RMWs
 *        atomic.
 *        It also has the nasty property that none of the buffers allocated
 *        for reading old data & parity can be freed until the XOR node fires.
 *        Need to fix this.
 *
 * A null qfuncs indicates single fault tolerant.
 *****************************************************************************/

void
rf_CommonCreateParityLoggingSmallWriteDAG(RF_Raid_t *raidPtr,
    RF_AccessStripeMap_t *asmap, RF_DagHeader_t *dag_h, void *bp,
    RF_RaidAccessFlags_t flags, RF_AllocListElem_t *allocList,
    RF_RedFuncs_t *pfuncs, RF_RedFuncs_t *qfuncs)
{
	RF_DagNode_t *xorNodes, *blockNode, *unblockNode, *nodes;
	RF_DagNode_t *readDataNodes, *readParityNodes;
	RF_DagNode_t *writeDataNodes, *lpuNodes;
	RF_DagNode_t *unlockDataNodes = NULL, *termNode;
	RF_PhysDiskAddr_t *pda = asmap->physInfo;
	int numDataNodes = asmap->numStripeUnitsAccessed;
	int numParityNodes = (asmap->parityInfo->next) ? 2 : 1;
	int i, j, nNodes, totalNumNodes;
	RF_ReconUnitNum_t which_ru;
	int (*func) (RF_DagNode_t * node), (*undoFunc) (RF_DagNode_t * node);
	int (*qfunc) (RF_DagNode_t * node);
	char*name, *qname;
	RF_StripeNum_t parityStripeID =
	    rf_RaidAddressToParityStripeID(&(raidPtr->Layout),
	     asmap->raidAddress, &which_ru);
	long nfaults = qfuncs ? 2 : 1;
	int lu_flag = (rf_enableAtomicRMW) ? 1 : 0;	/* Lock/unlock flag. */

	if (rf_dagDebug)
		printf("[Creating parity-logging small-write DAG]\n");
	RF_ASSERT(numDataNodes > 0);
	RF_ASSERT(nfaults == 1);
	dag_h->creator = "ParityLoggingSmallWriteDAG";

	/*
	 * DAG creation occurs in three steps:
	 * 1. Count the number of nodes in the DAG.
	 * 2. Create the nodes.
	 * 3. Initialize the nodes.
	 * 4. Connect the nodes.
	 */

	/* Step 1. Compute number of nodes in the graph. */

	/*
	 * Number of nodes: a read and write for each data unit, a redundancy
	 * computation node for each parity node, a read and Lpu for each
	 * parity unit, a block and unblock node (2), a terminator node if
	 * atomic RMW, an unlock node for each data and redundancy unit.
	 */
	totalNumNodes = (2 * numDataNodes) + numParityNodes +
	    (2 * numParityNodes) + 3;
	if (lu_flag)
		totalNumNodes += numDataNodes;

	nNodes = numDataNodes + numParityNodes;

	dag_h->numCommitNodes = numDataNodes + numParityNodes;
	dag_h->numCommits = 0;
	dag_h->numSuccedents = 1;

	/* Step 2. Create the nodes. */
	RF_CallocAndAdd(nodes, totalNumNodes, sizeof(RF_DagNode_t),
	    (RF_DagNode_t *), allocList);
	i = 0;
	blockNode = &nodes[i];
	i += 1;
	unblockNode = &nodes[i];
	i += 1;
	readDataNodes = &nodes[i];
	i += numDataNodes;
	readParityNodes = &nodes[i];
	i += numParityNodes;
	writeDataNodes = &nodes[i];
	i += numDataNodes;
	lpuNodes = &nodes[i];
	i += numParityNodes;
	xorNodes = &nodes[i];
	i += numParityNodes;
	termNode = &nodes[i];
	i += 1;
	if (lu_flag) {
		unlockDataNodes = &nodes[i];
		i += numDataNodes;
	}
	RF_ASSERT(i == totalNumNodes);

	/* Step 3. Initialize the nodes. */
	/* Initialize block node (Nil). */
	rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc,
	    rf_NullNodeUndoFunc, NULL, nNodes, 0, 0, 0, dag_h,
	    "Nil", allocList);

	/* Initialize unblock node (Nil). */
	rf_InitNode(unblockNode, rf_wait, RF_FALSE, rf_NullNodeFunc,
	    rf_NullNodeUndoFunc, NULL, 1, nNodes, 0, 0, dag_h,
	    "Nil", allocList);

	/* Initialize terminatory node (Trm). */
	rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc,
	    rf_TerminateUndoFunc, NULL, 0, 1, 0, 0, dag_h, "Trm", allocList);

	/* Initialize nodes which read old data (Rod). */
	for (i = 0; i < numDataNodes; i++) {
		rf_InitNode(&readDataNodes[i], rf_wait, RF_FALSE,
		    rf_DiskReadFunc, rf_DiskReadUndoFunc, rf_GenericWakeupFunc,
		    nNodes, 1, 4, 0, dag_h, "Rod", allocList);
		RF_ASSERT(pda != NULL);
		/* Physical disk addr desc. */
		readDataNodes[i].params[0].p = pda;
		readDataNodes[i].params[1].p = rf_AllocBuffer(raidPtr, dag_h,
		    pda, allocList);	/* Buffer to hold old data. */
		readDataNodes[i].params[2].v = parityStripeID;
		readDataNodes[i].params[3].v =
		    RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, lu_flag,
		    0, which_ru);
		pda = pda->next;
		readDataNodes[i].propList[0] = NULL;
		readDataNodes[i].propList[1] = NULL;
	}

	/* Initialize nodes which read old parity (Rop). */
	pda = asmap->parityInfo;
	i = 0;
	for (i = 0; i < numParityNodes; i++) {
		RF_ASSERT(pda != NULL);
		rf_InitNode(&readParityNodes[i], rf_wait, RF_FALSE,
		    rf_DiskReadFunc, rf_DiskReadUndoFunc, rf_GenericWakeupFunc,
		    nNodes, 1, 4, 0, dag_h, "Rop", allocList);
		readParityNodes[i].params[0].p = pda;
		readParityNodes[i].params[1].p = rf_AllocBuffer(raidPtr, dag_h,
		    pda, allocList);	/* Buffer to hold old parity. */
		readParityNodes[i].params[2].v = parityStripeID;
		readParityNodes[i].params[3].v =
		    RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, which_ru);
		readParityNodes[i].propList[0] = NULL;
		pda = pda->next;
	}

	/* Initialize nodes which write new data (Wnd). */
	pda = asmap->physInfo;
	for (i = 0; i < numDataNodes; i++) {
		RF_ASSERT(pda != NULL);
		rf_InitNode(&writeDataNodes[i], rf_wait, RF_TRUE,
		    rf_DiskWriteFunc, rf_DiskWriteUndoFunc,
		    rf_GenericWakeupFunc, 1, nNodes, 4, 0, dag_h,
		    "Wnd", allocList);
		/* Physical disk addr desc. */
		writeDataNodes[i].params[0].p = pda;
		/* Buffer holding new data to be written. */
		writeDataNodes[i].params[1].p = pda->bufPtr;
		writeDataNodes[i].params[2].v = parityStripeID;
		writeDataNodes[i].params[3].v =
		    RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, which_ru);

		if (lu_flag) {
			/* Initialize node to unlock the disk queue. */
			rf_InitNode(&unlockDataNodes[i], rf_wait, RF_FALSE,
			    rf_DiskUnlockFunc, rf_DiskUnlockUndoFunc,
			    rf_GenericWakeupFunc, 1, 1, 2, 0, dag_h,
			    "Und", allocList);
			/* Physical disk addr desc. */
			unlockDataNodes[i].params[0].p = pda;
			unlockDataNodes[i].params[1].v =
			    RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0,
			    lu_flag, which_ru);
		}
		pda = pda->next;
	}


	/* Initialize nodes which compute new parity. */
	/*
	 * We use the simple XOR func in the double-XOR case, and when we're
	 * accessing only a portion of one stripe unit. The distinction
	 * between the two is that the regular XOR func assumes that the
	 * targbuf is a full SU in size, and examines the pda associated with
	 * the buffer to decide where within the buffer to XOR the data,
	 * whereas the simple XOR func just XORs the data into the start of
	 * the buffer.
	 */
	if ((numParityNodes == 2) || ((numDataNodes == 1) &&
	    (asmap->totalSectorsAccessed <
	     raidPtr->Layout.sectorsPerStripeUnit))) {
		func = pfuncs->simple;
		undoFunc = rf_NullNodeUndoFunc;
		name = pfuncs->SimpleName;
		if (qfuncs) {
			qfunc = qfuncs->simple;
			qname = qfuncs->SimpleName;
		}
	} else {
		func = pfuncs->regular;
		undoFunc = rf_NullNodeUndoFunc;
		name = pfuncs->RegularName;
		if (qfuncs) {
			qfunc = qfuncs->regular;
			qname = qfuncs->RegularName;
		}
	}
	/*
	 * Initialize the xor nodes: params are {pda,buf} from {Rod,Wnd,Rop}
	 * nodes, and raidPtr.
	 */
	if (numParityNodes == 2) {	/* Double-XOR case. */
		for (i = 0; i < numParityNodes; i++) {
			rf_InitNode(&xorNodes[i], rf_wait, RF_TRUE, func,
			    undoFunc, NULL, 1, nNodes, 7, 1, dag_h, name,
			    allocList);	/* No wakeup func for XOR. */
			xorNodes[i].flags |= RF_DAGNODE_FLAG_YIELD;
			xorNodes[i].params[0] = readDataNodes[i].params[0];
			xorNodes[i].params[1] = readDataNodes[i].params[1];
			xorNodes[i].params[2] = readParityNodes[i].params[0];
			xorNodes[i].params[3] = readParityNodes[i].params[1];
			xorNodes[i].params[4] = writeDataNodes[i].params[0];
			xorNodes[i].params[5] = writeDataNodes[i].params[1];
			xorNodes[i].params[6].p = raidPtr;
			/* Use old parity buf as target buf. */
			xorNodes[i].results[0] = readParityNodes[i].params[1].p;
		}
	} else {
		/* There is only one xor node in this case. */
		rf_InitNode(&xorNodes[0], rf_wait, RF_TRUE, func, undoFunc,
		    NULL, 1, nNodes,
		    (2 * (numDataNodes + numDataNodes + 1) + 1), 1,
		    dag_h, name, allocList);
		xorNodes[0].flags |= RF_DAGNODE_FLAG_YIELD;
		for (i = 0; i < numDataNodes + 1; i++) {
			/* Set up params related to Rod and Rop nodes. */
			xorNodes[0].params[2 * i + 0] =
			    readDataNodes[i].params[0];	/* pda */
			xorNodes[0].params[2 * i + 1] =
			    readDataNodes[i].params[1];	/* Buffer pointer */
		}
		for (i = 0; i < numDataNodes; i++) {
			/* Set up params related to Wnd and Wnp nodes. */
			xorNodes[0].params[2 * (numDataNodes + 1 + i) + 0] =
			    writeDataNodes[i].params[0]; /* pda */
			xorNodes[0].params[2 * (numDataNodes + 1 + i) + 1] =
			    writeDataNodes[i].params[1]; /* Buffer pointer */
		}
		xorNodes[0].params[2 * (numDataNodes + numDataNodes + 1)].p =
		    raidPtr;	/* Xor node needs to get at RAID information. */
		xorNodes[0].results[0] = readParityNodes[0].params[1].p;
	}

	/* Initialize the log node(s). */
	pda = asmap->parityInfo;
	for (i = 0; i < numParityNodes; i++) {
		RF_ASSERT(pda);
		rf_InitNode(&lpuNodes[i], rf_wait, RF_FALSE,
		    rf_ParityLogUpdateFunc, rf_ParityLogUpdateUndoFunc,
		    rf_GenericWakeupFunc, 1, 1, 2, 0, dag_h, "Lpu", allocList);
		lpuNodes[i].params[0].p = pda;	/* PhysDiskAddr of parity. */
		/* Buffer pointer to parity. */
		lpuNodes[i].params[1].p = xorNodes[i].results[0];
		pda = pda->next;
	}


	/* Step 4. Connect the nodes. */

	/* Connect header to block node. */
	RF_ASSERT(dag_h->numSuccedents == 1);
	RF_ASSERT(blockNode->numAntecedents == 0);
	dag_h->succedents[0] = blockNode;

	/* Connect block node to read old data nodes. */
	RF_ASSERT(blockNode->numSuccedents == (numDataNodes + numParityNodes));
	for (i = 0; i < numDataNodes; i++) {
		blockNode->succedents[i] = &readDataNodes[i];
		RF_ASSERT(readDataNodes[i].numAntecedents == 1);
		readDataNodes[i].antecedents[0] = blockNode;
		readDataNodes[i].antType[0] = rf_control;
	}

	/* Connect block node to read old parity nodes. */
	for (i = 0; i < numParityNodes; i++) {
		blockNode->succedents[numDataNodes + i] = &readParityNodes[i];
		RF_ASSERT(readParityNodes[i].numAntecedents == 1);
		readParityNodes[i].antecedents[0] = blockNode;
		readParityNodes[i].antType[0] = rf_control;
	}

	/* Connect read old data nodes to write new data nodes. */
	for (i = 0; i < numDataNodes; i++) {
		RF_ASSERT(readDataNodes[i].numSuccedents ==
		          numDataNodes + numParityNodes);
		for (j = 0; j < numDataNodes; j++) {
			RF_ASSERT(writeDataNodes[j].numAntecedents ==
			          numDataNodes + numParityNodes);
			readDataNodes[i].succedents[j] = &writeDataNodes[j];
			writeDataNodes[j].antecedents[i] = &readDataNodes[i];
			if (i == j)
				writeDataNodes[j].antType[i] = rf_antiData;
			else
				writeDataNodes[j].antType[i] = rf_control;
		}
	}

	/* Connect read old data nodes to xor nodes. */
	for (i = 0; i < numDataNodes; i++)
		for (j = 0; j < numParityNodes; j++) {
			RF_ASSERT(xorNodes[j].numAntecedents ==
			          numDataNodes + numParityNodes);
			readDataNodes[i].succedents[numDataNodes + j] =
			    &xorNodes[j];
			xorNodes[j].antecedents[i] = &readDataNodes[i];
			xorNodes[j].antType[i] = rf_trueData;
		}

	/* Connect read old parity nodes to write new data nodes. */
	for (i = 0; i < numParityNodes; i++) {
		RF_ASSERT(readParityNodes[i].numSuccedents ==
		          numDataNodes + numParityNodes);
		for (j = 0; j < numDataNodes; j++) {
			readParityNodes[i].succedents[j] = &writeDataNodes[j];
			writeDataNodes[j].antecedents[numDataNodes + i] =
			    &readParityNodes[i];
			writeDataNodes[j].antType[numDataNodes + i] =
			    rf_control;
		}
	}

	/* Connect read old parity nodes to xor nodes. */
	for (i = 0; i < numParityNodes; i++)
		for (j = 0; j < numParityNodes; j++) {
			readParityNodes[i].succedents[numDataNodes + j] =
			    &xorNodes[j];
			xorNodes[j].antecedents[numDataNodes + i] =
			    &readParityNodes[i];
			xorNodes[j].antType[numDataNodes + i] = rf_trueData;
		}

	/* Connect xor nodes to write new parity nodes. */
	for (i = 0; i < numParityNodes; i++) {
		RF_ASSERT(xorNodes[i].numSuccedents == 1);
		RF_ASSERT(lpuNodes[i].numAntecedents == 1);
		xorNodes[i].succedents[0] = &lpuNodes[i];
		lpuNodes[i].antecedents[0] = &xorNodes[i];
		lpuNodes[i].antType[0] = rf_trueData;
	}

	for (i = 0; i < numDataNodes; i++) {
		if (lu_flag) {
			/* Connect write new data nodes to unlock nodes. */
			RF_ASSERT(writeDataNodes[i].numSuccedents == 1);
			RF_ASSERT(unlockDataNodes[i].numAntecedents == 1);
			writeDataNodes[i].succedents[0] = &unlockDataNodes[i];
			unlockDataNodes[i].antecedents[0] = &writeDataNodes[i];
			unlockDataNodes[i].antType[0] = rf_control;

			/* Connect unlock nodes to unblock node. */
			RF_ASSERT(unlockDataNodes[i].numSuccedents == 1);
			RF_ASSERT(unblockNode->numAntecedents ==
			          (numDataNodes + (nfaults * numParityNodes)));
			unlockDataNodes[i].succedents[0] = unblockNode;
			unblockNode->antecedents[i] = &unlockDataNodes[i];
			unblockNode->antType[i] = rf_control;
		} else {
			/* Connect write new data nodes to unblock node. */
			RF_ASSERT(writeDataNodes[i].numSuccedents == 1);
			RF_ASSERT(unblockNode->numAntecedents ==
			          (numDataNodes + (nfaults * numParityNodes)));
			writeDataNodes[i].succedents[0] = unblockNode;
			unblockNode->antecedents[i] = &writeDataNodes[i];
			unblockNode->antType[i] = rf_control;
		}
	}

	/* Connect write new parity nodes to unblock node. */
	for (i = 0; i < numParityNodes; i++) {
		RF_ASSERT(lpuNodes[i].numSuccedents == 1);
		lpuNodes[i].succedents[0] = unblockNode;
		unblockNode->antecedents[numDataNodes + i] = &lpuNodes[i];
		unblockNode->antType[numDataNodes + i] = rf_control;
	}

	/* Connect unblock node to terminator. */
	RF_ASSERT(unblockNode->numSuccedents == 1);
	RF_ASSERT(termNode->numAntecedents == 1);
	RF_ASSERT(termNode->numSuccedents == 0);
	unblockNode->succedents[0] = termNode;
	termNode->antecedents[0] = unblockNode;
	termNode->antType[0] = rf_control;
}


void
rf_CreateParityLoggingSmallWriteDAG(RF_Raid_t *raidPtr,
    RF_AccessStripeMap_t *asmap, RF_DagHeader_t *dag_h, void *bp,
    RF_RaidAccessFlags_t flags, RF_AllocListElem_t *allocList,
    RF_RedFuncs_t *pfuncs, RF_RedFuncs_t *qfuncs)
{
	dag_h->creator = "ParityLoggingSmallWriteDAG";
	rf_CommonCreateParityLoggingSmallWriteDAG(raidPtr, asmap, dag_h, bp,
	    flags, allocList, &rf_xorFuncs, NULL);
}


void
rf_CreateParityLoggingLargeWriteDAG(RF_Raid_t *raidPtr,
    RF_AccessStripeMap_t *asmap, RF_DagHeader_t *dag_h, void *bp,
    RF_RaidAccessFlags_t flags, RF_AllocListElem_t *allocList, int nfaults,
    int (*redFunc) (RF_DagNode_t *))
{
	dag_h->creator = "ParityLoggingSmallWriteDAG";
	rf_CommonCreateParityLoggingLargeWriteDAG(raidPtr, asmap, dag_h, bp,
	    flags, allocList, 1, rf_RegularXorFunc);
}
#endif	/* RF_INCLUDE_PARITYLOGGING > 0 */