/*      $NetBSD: rf_dagdegrd.c,v 1.33 2022/01/24 09:14:37 andvar Exp $  */
/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: Mark Holland, Daniel Stodolsky, 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.
 */

/*
 * rf_dagdegrd.c
 *
 * code for creating degraded read DAGs
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rf_dagdegrd.c,v 1.33 2022/01/24 09:14:37 andvar Exp $");

#include <dev/raidframe/raidframevar.h>

#include "rf_archs.h"
#include "rf_raid.h"
#include "rf_dag.h"
#include "rf_dagutils.h"
#include "rf_dagfuncs.h"
#include "rf_debugMem.h"
#include "rf_general.h"
#include "rf_dagdegrd.h"
#include "rf_map.h"


/******************************************************************************
 *
 * General comments on DAG creation:
 *
 * All DAGs in this file use roll-away error recovery.  Each DAG has a single
 * commit node, usually called "Cmt."  If an error occurs before the Cmt node
 * is reached, the execution engine will halt forward execution and work
 * backward through the graph, executing the undo functions.  Assuming that
 * each node in the graph prior to the Cmt node are undoable and atomic - or -
 * does not make changes to permanent state, the graph will fail atomically.
 * If an error occurs after the Cmt node executes, the engine will roll-forward
 * through the graph, blindly executing nodes until it reaches the end.
 * If a graph reaches the end, it is assumed to have completed successfully.
 *
 * A graph has only 1 Cmt node.
 *
 */


/******************************************************************************
 *
 * The following wrappers map the standard DAG creation interface to the
 * DAG creation routines.  Additionally, these wrappers enable experimentation
 * with new DAG structures by providing an extra level of indirection, allowing
 * the DAG creation routines to be replaced at this single point.
 */

void
rf_CreateRaidFiveDegradedReadDAG(RF_Raid_t *raidPtr,
                                 RF_AccessStripeMap_t *asmap,
                                 RF_DagHeader_t *dag_h,
                                 void *bp,
                                 RF_RaidAccessFlags_t flags,
                                 RF_AllocListElem_t *allocList)
{
        rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
            &rf_xorRecoveryFuncs);
}


/******************************************************************************
 *
 * DAG creation code begins here
 */


/******************************************************************************
 * Create a degraded read DAG for RAID level 1
 *
 * Hdr -> Nil -> R(p/s)d -> Commit -> Trm
 *
 * The "Rd" node reads data from the surviving disk in the mirror pair
 *   Rpd - read of primary copy
 *   Rsd - read of secondary copy
 *
 * Parameters:  raidPtr   - description of the physical array
 *              asmap     - logical & physical addresses for this access
 *              bp        - buffer ptr (for holding write data)
 *              flags     - general flags (e.g. disk locking)
 *              allocList - list of memory allocated in DAG creation
 *****************************************************************************/

void
rf_CreateRaidOneDegradedReadDAG(RF_Raid_t *raidPtr,
                                RF_AccessStripeMap_t *asmap,
                                RF_DagHeader_t *dag_h,
                                void *bp,
                                RF_RaidAccessFlags_t flags,
                                RF_AllocListElem_t *allocList)
{
        RF_DagNode_t *rdNode, *blockNode, *commitNode, *termNode;
        RF_StripeNum_t parityStripeID;
        RF_ReconUnitNum_t which_ru;
        RF_PhysDiskAddr_t *pda;
        int     useMirror;

        useMirror = 0;
        parityStripeID = rf_RaidAddressToParityStripeID(&(raidPtr->Layout),
            asmap->raidAddress, &which_ru);
#if RF_DEBUG_DAG
        if (rf_dagDebug) {
                printf("[Creating RAID level 1 degraded read DAG]\n");
        }
#endif
        dag_h->creator = "RaidOneDegradedReadDAG";
        /* alloc the Wnd nodes and the Wmir node */
        if (asmap->numDataFailed == 0)
                useMirror = RF_FALSE;
        else
                useMirror = RF_TRUE;

        /* total number of nodes = 1 + (block + commit + terminator) */

        rdNode = rf_AllocDAGNode(raidPtr);
        rdNode->list_next = dag_h->nodes;
        dag_h->nodes = rdNode;

        blockNode = rf_AllocDAGNode(raidPtr);
        blockNode->list_next = dag_h->nodes;
        dag_h->nodes = blockNode;

        commitNode = rf_AllocDAGNode(raidPtr);
        commitNode->list_next = dag_h->nodes;
        dag_h->nodes = commitNode;

        termNode = rf_AllocDAGNode(raidPtr);
        termNode->list_next = dag_h->nodes;
        dag_h->nodes = termNode;

        /* this dag can not commit until the commit node is reached.   errors
         * prior to the commit point imply the dag has failed and must be
         * retried */
        dag_h->numCommitNodes = 1;
        dag_h->numCommits = 0;
        dag_h->numSuccedents = 1;

        /* initialize the block, commit, and terminator nodes */
        rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, 1, 0, 0, 0, dag_h, "Nil", allocList);
        rf_InitNode(commitNode, rf_wait, RF_TRUE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, 1, 1, 0, 0, dag_h, "Cmt", allocList);
        rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc, rf_TerminateUndoFunc,
            NULL, 0, 1, 0, 0, dag_h, "Trm", allocList);

        pda = asmap->physInfo;
        RF_ASSERT(pda != NULL);
        /* parityInfo must describe entire parity unit */
        RF_ASSERT(asmap->parityInfo->next == NULL);

        /* initialize the data node */
        if (!useMirror) {
                /* read primary copy of data */
                rf_InitNode(rdNode, rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc,
                    rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, "Rpd", allocList);
                rdNode->params[0].p = pda;
                rdNode->params[1].p = pda->bufPtr;
                rdNode->params[2].v = parityStripeID;
                rdNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY,
                                                       which_ru);
        } else {
                /* read secondary copy of data */
                rf_InitNode(rdNode, rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc,
                    rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, "Rsd", allocList);
                rdNode->params[0].p = asmap->parityInfo;
                rdNode->params[1].p = pda->bufPtr;
                rdNode->params[2].v = parityStripeID;
                rdNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY,
                                                       which_ru);
        }

        /* 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 rdnode */
        RF_ASSERT(blockNode->numSuccedents == 1);
        RF_ASSERT(rdNode->numAntecedents == 1);
        blockNode->succedents[0] = rdNode;
        rdNode->antecedents[0] = blockNode;
        rdNode->antType[0] = rf_control;

        /* connect rdnode to commit node */
        RF_ASSERT(rdNode->numSuccedents == 1);
        RF_ASSERT(commitNode->numAntecedents == 1);
        rdNode->succedents[0] = commitNode;
        commitNode->antecedents[0] = rdNode;
        commitNode->antType[0] = rf_control;

        /* connect commit node to terminator */
        RF_ASSERT(commitNode->numSuccedents == 1);
        RF_ASSERT(termNode->numAntecedents == 1);
        RF_ASSERT(termNode->numSuccedents == 0);
        commitNode->succedents[0] = termNode;
        termNode->antecedents[0] = commitNode;
        termNode->antType[0] = rf_control;
}



/******************************************************************************
 *
 * creates a DAG to perform a degraded-mode read of data within one stripe.
 * This DAG is as follows:
 *
 * Hdr -> Block -> Rud -> Xor -> Cmt -> T
 *              -> Rrd ->
 *              -> Rp -->
 *
 * Each R node is a successor of the L node
 * One successor arc from each R node goes to C, and the other to X
 * There is one Rud for each chunk of surviving user data requested by the
 * user, and one Rrd for each chunk of surviving user data _not_ being read by
 * the user
 * R = read, ud = user data, rd = recovery (surviving) data, p = parity
 * X = XOR, C = Commit, T = terminate
 *
 * The block node guarantees a single source node.
 *
 * Note:  The target buffer for the XOR node is set to the actual user buffer
 * where the failed data is supposed to end up.  This buffer is zero'd by the
 * code here.  Thus, if you create a degraded read dag, use it, and then
 * re-use, you have to be sure to zero the target buffer prior to the re-use.
 *
 * The recfunc argument at the end specifies the name and function used for
 * the redundancy
 * recovery function.
 *
 *****************************************************************************/

void
rf_CreateDegradedReadDAG(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asmap,
                         RF_DagHeader_t *dag_h, void *bp,
                         RF_RaidAccessFlags_t flags,
                         RF_AllocListElem_t *allocList,
                         const RF_RedFuncs_t *recFunc)
{
        RF_DagNode_t *rudNodes, *rrdNodes, *xorNode, *blockNode;
        RF_DagNode_t *commitNode, *rpNode, *termNode;
        RF_DagNode_t *tmpNode, *tmprudNode, *tmprrdNode;
        int     nRrdNodes, nRudNodes, nXorBufs, i;
        int     j, paramNum;
        RF_SectorCount_t sectorsPerSU;
        RF_ReconUnitNum_t which_ru;
        char    overlappingPDAs[RF_MAXCOL];/* a temporary array of flags */
        RF_AccessStripeMapHeader_t *new_asm_h[2];
        RF_PhysDiskAddr_t *pda, *parityPDA;
        RF_StripeNum_t parityStripeID;
        RF_PhysDiskAddr_t *failedPDA;
        RF_RaidLayout_t *layoutPtr;
        char   *rpBuf;

        layoutPtr = &(raidPtr->Layout);
        /* failedPDA points to the pda within the asm that targets the failed
         * disk */
        failedPDA = asmap->failedPDAs[0];
        parityStripeID = rf_RaidAddressToParityStripeID(layoutPtr,
            asmap->raidAddress, &which_ru);
        sectorsPerSU = layoutPtr->sectorsPerStripeUnit;

#if RF_DEBUG_DAG
        if (rf_dagDebug) {
                printf("[Creating degraded read DAG]\n");
        }
#endif
        RF_ASSERT(asmap->numDataFailed == 1);
        dag_h->creator = "DegradedReadDAG";

        /*
         * generate two ASMs identifying the surviving data we need
         * in order to recover the lost data
         */

        /* overlappingPDAs array must be zero'd */
        memset(overlappingPDAs, 0, RF_MAXCOL);
        rf_GenerateFailedAccessASMs(raidPtr, asmap, failedPDA, dag_h, new_asm_h, &nXorBufs,
            &rpBuf, overlappingPDAs, allocList);

        /*
         * create all the nodes at once
         *
         * -1 because no access is generated for the failed pda
         */
        nRudNodes = asmap->numStripeUnitsAccessed - 1;
        nRrdNodes = ((new_asm_h[0]) ? new_asm_h[0]->stripeMap->numStripeUnitsAccessed : 0) +
            ((new_asm_h[1]) ? new_asm_h[1]->stripeMap->numStripeUnitsAccessed : 0);

        blockNode = rf_AllocDAGNode(raidPtr);
        blockNode->list_next = dag_h->nodes;
        dag_h->nodes = blockNode;

        commitNode = rf_AllocDAGNode(raidPtr);
        commitNode->list_next = dag_h->nodes;
        dag_h->nodes = commitNode;

        xorNode = rf_AllocDAGNode(raidPtr);
        xorNode->list_next = dag_h->nodes;
        dag_h->nodes = xorNode;

        rpNode = rf_AllocDAGNode(raidPtr);
        rpNode->list_next = dag_h->nodes;
        dag_h->nodes = rpNode;

        termNode = rf_AllocDAGNode(raidPtr);
        termNode->list_next = dag_h->nodes;
        dag_h->nodes = termNode;

        for (i = 0; i < nRudNodes; i++) {
                tmpNode = rf_AllocDAGNode(raidPtr);
                tmpNode->list_next = dag_h->nodes;
                dag_h->nodes = tmpNode;
        }
        rudNodes = dag_h->nodes;

        for (i = 0; i < nRrdNodes; i++) {
                tmpNode = rf_AllocDAGNode(raidPtr);
                tmpNode->list_next = dag_h->nodes;
                dag_h->nodes = tmpNode;
        }
        rrdNodes = dag_h->nodes;

        /* initialize nodes */
        dag_h->numCommitNodes = 1;
        dag_h->numCommits = 0;
        /* this dag can not commit until the commit node is reached errors
         * prior to the commit point imply the dag has failed */
        dag_h->numSuccedents = 1;

        rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, nRudNodes + nRrdNodes + 1, 0, 0, 0, dag_h, "Nil", allocList);
        rf_InitNode(commitNode, rf_wait, RF_TRUE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, 1, 1, 0, 0, dag_h, "Cmt", allocList);
        rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc, rf_TerminateUndoFunc,
            NULL, 0, 1, 0, 0, dag_h, "Trm", allocList);
        rf_InitNode(xorNode, rf_wait, RF_FALSE, recFunc->simple, rf_NullNodeUndoFunc,
            NULL, 1, nRudNodes + nRrdNodes + 1, 2 * nXorBufs + 2, 1, dag_h,
            recFunc->SimpleName, allocList);

        /* fill in the Rud nodes */
        tmprudNode = rudNodes;
        for (pda = asmap->physInfo, i = 0; i < nRudNodes; i++, pda = pda->next) {
                if (pda == failedPDA) {
                        i--;
                        continue;
                }
                rf_InitNode(tmprudNode, rf_wait, RF_FALSE, rf_DiskReadFunc,
                    rf_DiskReadUndoFunc, rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h,
                    "Rud", allocList);
                RF_ASSERT(pda);
                tmprudNode->params[0].p = pda;
                tmprudNode->params[1].p = pda->bufPtr;
                tmprudNode->params[2].v = parityStripeID;
                tmprudNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);
                tmprudNode = tmprudNode->list_next;
        }

        /* fill in the Rrd nodes */
        i = 0;
        tmprrdNode = rrdNodes;
        if (new_asm_h[0]) {
                for (pda = new_asm_h[0]->stripeMap->physInfo;
                    i < new_asm_h[0]->stripeMap->numStripeUnitsAccessed;
                    i++, pda = pda->next) {
                        rf_InitNode(tmprrdNode, rf_wait, RF_FALSE, rf_DiskReadFunc,
                            rf_DiskReadUndoFunc, rf_GenericWakeupFunc, 1, 1, 4, 0,
                            dag_h, "Rrd", allocList);
                        RF_ASSERT(pda);
                        tmprrdNode->params[0].p = pda;
                        tmprrdNode->params[1].p = pda->bufPtr;
                        tmprrdNode->params[2].v = parityStripeID;
                        tmprrdNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);
                        tmprrdNode = tmprrdNode->list_next;
                }
        }
        if (new_asm_h[1]) {
                /* tmprrdNode = rrdNodes; */ /* don't set this here -- old code was using i+j, which means
                   we need to just continue using tmprrdNode for the next 'j' elements. */
                for (j = 0, pda = new_asm_h[1]->stripeMap->physInfo;
                    j < new_asm_h[1]->stripeMap->numStripeUnitsAccessed;
                    j++, pda = pda->next) {
                        rf_InitNode(tmprrdNode, rf_wait, RF_FALSE, rf_DiskReadFunc,
                            rf_DiskReadUndoFunc, rf_GenericWakeupFunc, 1, 1, 4, 0,
                            dag_h, "Rrd", allocList);
                        RF_ASSERT(pda);
                        tmprrdNode->params[0].p = pda;
                        tmprrdNode->params[1].p = pda->bufPtr;
                        tmprrdNode->params[2].v = parityStripeID;
                        tmprrdNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);
                        tmprrdNode = tmprrdNode->list_next;
                }
        }
        /* make a PDA for the parity unit */
        parityPDA = rf_AllocPhysDiskAddr(raidPtr);
        parityPDA->next = dag_h->pda_cleanup_list;
        dag_h->pda_cleanup_list = parityPDA;
        parityPDA->col = asmap->parityInfo->col;
        parityPDA->startSector = ((asmap->parityInfo->startSector / sectorsPerSU)
            * sectorsPerSU) + (failedPDA->startSector % sectorsPerSU);
        parityPDA->numSector = failedPDA->numSector;

        /* initialize the Rp node */
        rf_InitNode(rpNode, rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc,
            rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, "Rp ", allocList);
        rpNode->params[0].p = parityPDA;
        rpNode->params[1].p = rpBuf;
        rpNode->params[2].v = parityStripeID;
        rpNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);

        /*
         * the last and nastiest step is to assign all
         * the parameters of the Xor node
         */
        paramNum = 0;
        tmprrdNode = rrdNodes;
        for (i = 0; i < nRrdNodes; i++) {
                /* all the Rrd nodes need to be xored together */
                xorNode->params[paramNum++] = tmprrdNode->params[0];
                xorNode->params[paramNum++] = tmprrdNode->params[1];
                tmprrdNode = tmprrdNode->list_next;
        }
        tmprudNode = rudNodes;
        for (i = 0; i < nRudNodes; i++) {
                /* any Rud nodes that overlap the failed access need to be
                 * xored in */
                if (overlappingPDAs[i]) {
                        pda = rf_AllocPhysDiskAddr(raidPtr);
                        memcpy((char *) pda, (char *) tmprudNode->params[0].p, sizeof(RF_PhysDiskAddr_t));
                        /* add it into the pda_cleanup_list *after* the copy, TYVM */
                        pda->next = dag_h->pda_cleanup_list;
                        dag_h->pda_cleanup_list = pda;
                        rf_RangeRestrictPDA(raidPtr, failedPDA, pda, RF_RESTRICT_DOBUFFER, 0);
                        xorNode->params[paramNum++].p = pda;
                        xorNode->params[paramNum++].p = pda->bufPtr;
                }
                tmprudNode = tmprudNode->list_next;
        }

        /* install parity pda as last set of params to be xor'd */
        xorNode->params[paramNum++].p = parityPDA;
        xorNode->params[paramNum++].p = rpBuf;

        /*
         * the last 2 params to the recovery xor node are
         * the failed PDA and the raidPtr
         */
        xorNode->params[paramNum++].p = failedPDA;
        xorNode->params[paramNum++].p = raidPtr;
        RF_ASSERT(paramNum == 2 * nXorBufs + 2);

        /*
         * The xor node uses results[0] as the target buffer.
         * Set pointer and zero the buffer. In the kernel, this
         * may be a user buffer in which case we have to remap it.
         */
        xorNode->results[0] = failedPDA->bufPtr;
        memset(failedPDA->bufPtr, 0, rf_RaidAddressToByte(raidPtr,
                failedPDA->numSector));

        /* connect nodes to form graph */
        /* connect the header to the block node */
        RF_ASSERT(dag_h->numSuccedents == 1);
        RF_ASSERT(blockNode->numAntecedents == 0);
        dag_h->succedents[0] = blockNode;

        /* connect the block node to the read nodes */
        RF_ASSERT(blockNode->numSuccedents == (1 + nRrdNodes + nRudNodes));
        RF_ASSERT(rpNode->numAntecedents == 1);
        blockNode->succedents[0] = rpNode;
        rpNode->antecedents[0] = blockNode;
        rpNode->antType[0] = rf_control;
        tmprrdNode = rrdNodes;
        for (i = 0; i < nRrdNodes; i++) {
                RF_ASSERT(tmprrdNode->numSuccedents == 1);
                blockNode->succedents[1 + i] = tmprrdNode;
                tmprrdNode->antecedents[0] = blockNode;
                tmprrdNode->antType[0] = rf_control;
                tmprrdNode = tmprrdNode->list_next;
        }
        tmprudNode = rudNodes;
        for (i = 0; i < nRudNodes; i++) {
                RF_ASSERT(tmprudNode->numSuccedents == 1);
                blockNode->succedents[1 + nRrdNodes + i] = tmprudNode;
                tmprudNode->antecedents[0] = blockNode;
                tmprudNode->antType[0] = rf_control;
                tmprudNode = tmprudNode->list_next;
        }

        /* connect the read nodes to the xor node */
        RF_ASSERT(xorNode->numAntecedents == (1 + nRrdNodes + nRudNodes));
        RF_ASSERT(rpNode->numSuccedents == 1);
        rpNode->succedents[0] = xorNode;
        xorNode->antecedents[0] = rpNode;
        xorNode->antType[0] = rf_trueData;
        tmprrdNode = rrdNodes;
        for (i = 0; i < nRrdNodes; i++) {
                RF_ASSERT(tmprrdNode->numSuccedents == 1);
                tmprrdNode->succedents[0] = xorNode;
                xorNode->antecedents[1 + i] = tmprrdNode;
                xorNode->antType[1 + i] = rf_trueData;
                tmprrdNode = tmprrdNode->list_next;
        }
        tmprudNode = rudNodes;
        for (i = 0; i < nRudNodes; i++) {
                RF_ASSERT(tmprudNode->numSuccedents == 1);
                tmprudNode->succedents[0] = xorNode;
                xorNode->antecedents[1 + nRrdNodes + i] = tmprudNode;
                xorNode->antType[1 + nRrdNodes + i] = rf_trueData;
                tmprudNode = tmprudNode->list_next;
        }

        /* connect the xor node to the commit node */
        RF_ASSERT(xorNode->numSuccedents == 1);
        RF_ASSERT(commitNode->numAntecedents == 1);
        xorNode->succedents[0] = commitNode;
        commitNode->antecedents[0] = xorNode;
        commitNode->antType[0] = rf_control;

        /* connect the termNode to the commit node */
        RF_ASSERT(commitNode->numSuccedents == 1);
        RF_ASSERT(termNode->numAntecedents == 1);
        RF_ASSERT(termNode->numSuccedents == 0);
        commitNode->succedents[0] = termNode;
        termNode->antType[0] = rf_control;
        termNode->antecedents[0] = commitNode;
}

#if (RF_INCLUDE_CHAINDECLUSTER > 0)
/******************************************************************************
 * Create a degraded read DAG for Chained Declustering
 *
 * Hdr -> Nil -> R(p/s)d -> Cmt -> Trm
 *
 * The "Rd" node reads data from the surviving disk in the mirror pair
 *   Rpd - read of primary copy
 *   Rsd - read of secondary copy
 *
 * Parameters:  raidPtr   - description of the physical array
 *              asmap     - logical & physical addresses for this access
 *              bp        - buffer ptr (for holding write data)
 *              flags     - general flags (e.g. disk locking)
 *              allocList - list of memory allocated in DAG creation
 *****************************************************************************/

void
rf_CreateRaidCDegradedReadDAG(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asmap,
                              RF_DagHeader_t *dag_h, void *bp,
                              RF_RaidAccessFlags_t flags,
                              RF_AllocListElem_t *allocList)
{
        RF_DagNode_t *nodes, *rdNode, *blockNode, *commitNode, *termNode;
        RF_StripeNum_t parityStripeID;
        int     useMirror, i, shiftable;
        RF_ReconUnitNum_t which_ru;
        RF_PhysDiskAddr_t *pda;

        if ((asmap->numDataFailed + asmap->numParityFailed) == 0) {
                shiftable = RF_TRUE;
        } else {
                shiftable = RF_FALSE;
        }
        useMirror = 0;
        parityStripeID = rf_RaidAddressToParityStripeID(&(raidPtr->Layout),
            asmap->raidAddress, &which_ru);

#if RF_DEBUG_DAG
        if (rf_dagDebug) {
                printf("[Creating RAID C degraded read DAG]\n");
        }
#endif
        dag_h->creator = "RaidCDegradedReadDAG";
        /* alloc the Wnd nodes and the Wmir node */
        if (asmap->numDataFailed == 0)
                useMirror = RF_FALSE;
        else
                useMirror = RF_TRUE;

        /* total number of nodes = 1 + (block + commit + terminator) */
        nodes = RF_MallocAndAdd(4 * sizeof(*nodes), allocList);
        i = 0;
        rdNode = &nodes[i];
        i++;
        blockNode = &nodes[i];
        i++;
        commitNode = &nodes[i];
        i++;
        termNode = &nodes[i];
        i++;

        /*
         * This dag can not commit until the commit node is reached.
         * Errors prior to the commit point imply the dag has failed
         * and must be retried.
         */
        dag_h->numCommitNodes = 1;
        dag_h->numCommits = 0;
        dag_h->numSuccedents = 1;

        /* initialize the block, commit, and terminator nodes */
        rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, 1, 0, 0, 0, dag_h, "Nil", allocList);
        rf_InitNode(commitNode, rf_wait, RF_TRUE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, 1, 1, 0, 0, dag_h, "Cmt", allocList);
        rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc, rf_TerminateUndoFunc,
            NULL, 0, 1, 0, 0, dag_h, "Trm", allocList);

        pda = asmap->physInfo;
        RF_ASSERT(pda != NULL);
        /* parityInfo must describe entire parity unit */
        RF_ASSERT(asmap->parityInfo->next == NULL);

        /* initialize the data node */
        if (!useMirror) {
                rf_InitNode(rdNode, rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc,
                    rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, "Rpd", allocList);
                if (shiftable && rf_compute_workload_shift(raidPtr, pda)) {
                        /* shift this read to the next disk in line */
                        rdNode->params[0].p = asmap->parityInfo;
                        rdNode->params[1].p = pda->bufPtr;
                        rdNode->params[2].v = parityStripeID;
                        rdNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);
                } else {
                        /* read primary copy */
                        rdNode->params[0].p = pda;
                        rdNode->params[1].p = pda->bufPtr;
                        rdNode->params[2].v = parityStripeID;
                        rdNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);
                }
        } else {
                /* read secondary copy of data */
                rf_InitNode(rdNode, rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc,
                    rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, "Rsd", allocList);
                rdNode->params[0].p = asmap->parityInfo;
                rdNode->params[1].p = pda->bufPtr;
                rdNode->params[2].v = parityStripeID;
                rdNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);
        }

        /* 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 rdnode */
        RF_ASSERT(blockNode->numSuccedents == 1);
        RF_ASSERT(rdNode->numAntecedents == 1);
        blockNode->succedents[0] = rdNode;
        rdNode->antecedents[0] = blockNode;
        rdNode->antType[0] = rf_control;

        /* connect rdnode to commit node */
        RF_ASSERT(rdNode->numSuccedents == 1);
        RF_ASSERT(commitNode->numAntecedents == 1);
        rdNode->succedents[0] = commitNode;
        commitNode->antecedents[0] = rdNode;
        commitNode->antType[0] = rf_control;

        /* connect commit node to terminator */
        RF_ASSERT(commitNode->numSuccedents == 1);
        RF_ASSERT(termNode->numAntecedents == 1);
        RF_ASSERT(termNode->numSuccedents == 0);
        commitNode->succedents[0] = termNode;
        termNode->antecedents[0] = commitNode;
        termNode->antType[0] = rf_control;
}
#endif /* (RF_INCLUDE_CHAINDECLUSTER > 0) */

#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0) || (RF_INCLUDE_EVENODD > 0)
/*
 * XXX move this elsewhere?
 */
void
rf_DD_GenerateFailedAccessASMs(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asmap,
                               RF_PhysDiskAddr_t **pdap, int *nNodep,
                               RF_PhysDiskAddr_t **pqpdap, int *nPQNodep,
                               RF_AllocListElem_t *allocList)
{
        RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
        int     PDAPerDisk, i;
        RF_SectorCount_t secPerSU = layoutPtr->sectorsPerStripeUnit;
        int     numDataCol = layoutPtr->numDataCol;
        int     state;
        RF_SectorNum_t suoff, suend;
        unsigned firstDataCol, napdas, count;
        RF_SectorNum_t fone_start, fone_end, ftwo_start = 0, ftwo_end = 0;
        RF_PhysDiskAddr_t *fone = asmap->failedPDAs[0], *ftwo = asmap->failedPDAs[1];
        RF_PhysDiskAddr_t *pda_p;
        RF_PhysDiskAddr_t *phys_p;
        RF_RaidAddr_t sosAddr;

        /* determine how many pda's we will have to generate per unaccess
         * stripe. If there is only one failed data unit, it is one; if two,
         * possibly two, depending whether they overlap. */

        fone_start = rf_StripeUnitOffset(layoutPtr, fone->startSector);
        fone_end = fone_start + fone->numSector;

#define BUF_ALLOC(num) \
  RF_MallocAndAdd(rf_RaidAddressToByte(raidPtr, num), allocList)
#define CONS_PDA(if,start,num) \
  pda_p->col = asmap->if->col; \
  pda_p->startSector = ((asmap->if->startSector / secPerSU) * secPerSU) + start; \
  pda_p->numSector = num; \
  pda_p->next = NULL; \
  pda_p->bufPtr = BUF_ALLOC(num)

        if (asmap->numDataFailed == 1) {
                PDAPerDisk = 1;
                state = 1;
                *pqpdap = RF_MallocAndAdd(2 * sizeof(**pqpdap), allocList);
                pda_p = *pqpdap;
                /* build p */
                CONS_PDA(parityInfo, fone_start, fone->numSector);
                pda_p->type = RF_PDA_TYPE_PARITY;
                pda_p++;
                /* build q */
                CONS_PDA(qInfo, fone_start, fone->numSector);
                pda_p->type = RF_PDA_TYPE_Q;
        } else {
                ftwo_start = rf_StripeUnitOffset(layoutPtr, ftwo->startSector);
                ftwo_end = ftwo_start + ftwo->numSector;
                if (fone->numSector + ftwo->numSector > secPerSU) {
                        PDAPerDisk = 1;
                        state = 2;
                        *pqpdap = RF_MallocAndAdd(2 * sizeof(**pqpdap), allocList);
                        pda_p = *pqpdap;
                        CONS_PDA(parityInfo, 0, secPerSU);
                        pda_p->type = RF_PDA_TYPE_PARITY;
                        pda_p++;
                        CONS_PDA(qInfo, 0, secPerSU);
                        pda_p->type = RF_PDA_TYPE_Q;
                } else {
                        PDAPerDisk = 2;
                        state = 3;
                        /* four of them, fone, then ftwo */
                        *pqpdap = RF_MallocAndAdd(4 * sizeof(**pqpdap), allocList);
                        pda_p = *pqpdap;
                        CONS_PDA(parityInfo, fone_start, fone->numSector);
                        pda_p->type = RF_PDA_TYPE_PARITY;
                        pda_p++;
                        CONS_PDA(qInfo, fone_start, fone->numSector);
                        pda_p->type = RF_PDA_TYPE_Q;
                        pda_p++;
                        CONS_PDA(parityInfo, ftwo_start, ftwo->numSector);
                        pda_p->type = RF_PDA_TYPE_PARITY;
                        pda_p++;
                        CONS_PDA(qInfo, ftwo_start, ftwo->numSector);
                        pda_p->type = RF_PDA_TYPE_Q;
                }
        }
        /* figure out number of nonaccessed pda */
        napdas = PDAPerDisk * (numDataCol - asmap->numStripeUnitsAccessed - (ftwo == NULL ? 1 : 0));
        *nPQNodep = PDAPerDisk;

        /* sweep over the over accessed pda's, figuring out the number of
         * additional pda's to generate. Of course, skip the failed ones */

        count = 0;
        for (pda_p = asmap->physInfo; pda_p; pda_p = pda_p->next) {
                if ((pda_p == fone) || (pda_p == ftwo))
                        continue;
                suoff = rf_StripeUnitOffset(layoutPtr, pda_p->startSector);
                suend = suoff + pda_p->numSector;
                switch (state) {
                case 1: /* one failed PDA to overlap */
                        /* if a PDA doesn't contain the failed unit, it can
                         * only miss the start or end, not both */
                        if ((suoff > fone_start) || (suend < fone_end))
                                count++;
                        break;
                case 2: /* whole stripe */
                        if (suoff)      /* leak at beginning */
                                count++;
                        if (suend < numDataCol) /* leak at end */
                                count++;
                        break;
                case 3: /* two disjoint units */
                        if ((suoff > fone_start) || (suend < fone_end))
                                count++;
                        if ((suoff > ftwo_start) || (suend < ftwo_end))
                                count++;
                        break;
                default:
                        RF_PANIC();
                }
        }

        napdas += count;
        *nNodep = napdas;
        if (napdas == 0)
                return;         /* short circuit */

        /* allocate up our list of pda's */

        pda_p = RF_MallocAndAdd(napdas * sizeof(*pdap), allocList);
        *pdap = pda_p;

        /* linkem together */
        for (i = 0; i < (napdas - 1); i++)
                pda_p[i].next = pda_p + (i + 1);

        /* march through the one's up to the first accessed disk */
        firstDataCol = rf_RaidAddressToStripeUnitID(&(raidPtr->Layout), asmap->physInfo->raidAddress) % numDataCol;
        sosAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr, asmap->raidAddress);
        for (i = 0; i < firstDataCol; i++) {
                if ((pda_p - (*pdap)) == napdas)
                        continue;
                pda_p->type = RF_PDA_TYPE_DATA;
                pda_p->raidAddress = sosAddr + (i * secPerSU);
                (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                /* skip over dead disks */
                if (RF_DEAD_DISK(raidPtr->Disks[pda_p->col].status))
                        continue;
                switch (state) {
                case 1: /* fone */
                        pda_p->numSector = fone->numSector;
                        pda_p->raidAddress += fone_start;
                        pda_p->startSector += fone_start;
                        pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                        break;
                case 2: /* full stripe */
                        pda_p->numSector = secPerSU;
                        pda_p->bufPtr = BUF_ALLOC(secPerSU);
                        break;
                case 3: /* two slabs */
                        pda_p->numSector = fone->numSector;
                        pda_p->raidAddress += fone_start;
                        pda_p->startSector += fone_start;
                        pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                        pda_p++;
                        pda_p->type = RF_PDA_TYPE_DATA;
                        pda_p->raidAddress = sosAddr + (i * secPerSU);
                        (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                        pda_p->numSector = ftwo->numSector;
                        pda_p->raidAddress += ftwo_start;
                        pda_p->startSector += ftwo_start;
                        pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                        break;
                default:
                        RF_PANIC();
                }
                pda_p++;
        }

        /* march through the touched stripe units */
        for (phys_p = asmap->physInfo; phys_p; phys_p = phys_p->next, i++) {
                if ((phys_p == asmap->failedPDAs[0]) || (phys_p == asmap->failedPDAs[1]))
                        continue;
                suoff = rf_StripeUnitOffset(layoutPtr, phys_p->startSector);
                suend = suoff + phys_p->numSector;
                switch (state) {
                case 1: /* single buffer */
                        if (suoff > fone_start) {
                                RF_ASSERT(suend >= fone_end);
                                /* The data read starts after the mapped
                                 * access, snip off the beginning */
                                pda_p->numSector = suoff - fone_start;
                                pda_p->raidAddress = sosAddr + (i * secPerSU) + fone_start;
                                (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                                pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                                pda_p++;
                        }
                        if (suend < fone_end) {
                                RF_ASSERT(suoff <= fone_start);
                                /* The data read stops before the end of the
                                 * failed access, extend */
                                pda_p->numSector = fone_end - suend;
                                pda_p->raidAddress = sosAddr + (i * secPerSU) + suend;  /* off by one? */
                                (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                                pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                                pda_p++;
                        }
                        break;
                case 2: /* whole stripe unit */
                        RF_ASSERT((suoff == 0) || (suend == secPerSU));
                        if (suend < secPerSU) { /* short read, snip from end
                                                 * on */
                                pda_p->numSector = secPerSU - suend;
                                pda_p->raidAddress = sosAddr + (i * secPerSU) + suend;  /* off by one? */
                                (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                                pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                                pda_p++;
                        } else
                                if (suoff > 0) {        /* short at front */
                                        pda_p->numSector = suoff;
                                        pda_p->raidAddress = sosAddr + (i * secPerSU);
                                        (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                                        pda_p->bufPtr =
                                            BUF_ALLOC(pda_p->numSector);
                                        pda_p++;
                                }
                        break;
                case 3: /* two nonoverlapping failures */
                        if ((suoff > fone_start) || (suend < fone_end)) {
                                if (suoff > fone_start) {
                                        RF_ASSERT(suend >= fone_end);
                                        /* The data read starts after the
                                         * mapped access, snip off the
                                         * beginning */
                                        pda_p->numSector = suoff - fone_start;
                                        pda_p->raidAddress = sosAddr + (i * secPerSU) + fone_start;
                                        (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                                        pda_p->bufPtr =
                                            BUF_ALLOC(pda_p->numSector);
                                        pda_p++;
                                }
                                if (suend < fone_end) {
                                        RF_ASSERT(suoff <= fone_start);
                                        /* The data read stops before the end
                                         * of the failed access, extend */
                                        pda_p->numSector = fone_end - suend;
                                        pda_p->raidAddress = sosAddr + (i * secPerSU) + suend;  /* off by one? */
                                        (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                                        pda_p->bufPtr =
                                            BUF_ALLOC(pda_p->numSector);
                                        pda_p++;
                                }
                        }
                        if ((suoff > ftwo_start) || (suend < ftwo_end)) {
                                if (suoff > ftwo_start) {
                                        RF_ASSERT(suend >= ftwo_end);
                                        /* The data read starts after the
                                         * mapped access, snip off the
                                         * beginning */
                                        pda_p->numSector = suoff - ftwo_start;
                                        pda_p->raidAddress = sosAddr + (i * secPerSU) + ftwo_start;
                                        (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                                        pda_p->bufPtr =
                                            BUF_ALLOC(pda_p->numSector);
                                        pda_p++;
                                }
                                if (suend < ftwo_end) {
                                        RF_ASSERT(suoff <= ftwo_start);
                                        /* The data read stops before the end
                                         * of the failed access, extend */
                                        pda_p->numSector = ftwo_end - suend;
                                        pda_p->raidAddress = sosAddr + (i * secPerSU) + suend;  /* off by one? */
                                        (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                                        pda_p->bufPtr =
                                            BUF_ALLOC(pda_p->numSector);
                                        pda_p++;
                                }
                        }
                        break;
                default:
                        RF_PANIC();
                }
        }

        /* after the last accessed disk */
        for (; i < numDataCol; i++) {
                if ((pda_p - (*pdap)) == napdas)
                        continue;
                pda_p->type = RF_PDA_TYPE_DATA;
                pda_p->raidAddress = sosAddr + (i * secPerSU);
                (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                /* skip over dead disks */
                if (RF_DEAD_DISK(raidPtr->Disks[pda_p->col].status))
                        continue;
                switch (state) {
                case 1: /* fone */
                        pda_p->numSector = fone->numSector;
                        pda_p->raidAddress += fone_start;
                        pda_p->startSector += fone_start;
                        pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                        break;
                case 2: /* full stripe */
                        pda_p->numSector = secPerSU;
                        pda_p->bufPtr = BUF_ALLOC(secPerSU);
                        break;
                case 3: /* two slabs */
                        pda_p->numSector = fone->numSector;
                        pda_p->raidAddress += fone_start;
                        pda_p->startSector += fone_start;
                        pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                        pda_p++;
                        pda_p->type = RF_PDA_TYPE_DATA;
                        pda_p->raidAddress = sosAddr + (i * secPerSU);
                        (raidPtr->Layout.map->MapSector) (raidPtr, pda_p->raidAddress, &(pda_p->col), &(pda_p->startSector), 0);
                        pda_p->numSector = ftwo->numSector;
                        pda_p->raidAddress += ftwo_start;
                        pda_p->startSector += ftwo_start;
                        pda_p->bufPtr = BUF_ALLOC(pda_p->numSector);
                        break;
                default:
                        RF_PANIC();
                }
                pda_p++;
        }

        RF_ASSERT(pda_p - *pdap == napdas);
        return;
}
#define INIT_DISK_NODE(node,name) \
rf_InitNode(node, rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc, rf_GenericWakeupFunc, 2,1,4,0, dag_h, name, allocList); \
(node)->succedents[0] = unblockNode; \
(node)->succedents[1] = recoveryNode; \
(node)->antecedents[0] = blockNode; \
(node)->antType[0] = rf_control

#define DISK_NODE_PARAMS(_node_,_p_) \
  (_node_).params[0].p = _p_ ; \
  (_node_).params[1].p = (_p_)->bufPtr; \
  (_node_).params[2].v = parityStripeID; \
  (_node_).params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru)

void
rf_DoubleDegRead(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asmap,
                 RF_DagHeader_t *dag_h, void *bp,
                 RF_RaidAccessFlags_t flags,
                 RF_AllocListElem_t *allocList,
                 const char *redundantReadNodeName,
                 const char *recoveryNodeName,
                 void (*recovFunc) (RF_DagNode_t *))
{
        RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
        RF_DagNode_t *nodes, *rudNodes, *rrdNodes, *recoveryNode, *blockNode,
               *unblockNode, *rpNodes, *rqNodes, *termNode;
        RF_PhysDiskAddr_t *pda, *pqPDAs;
        RF_PhysDiskAddr_t *npdas;
        int     nNodes, nRrdNodes, nRudNodes, i;
        RF_ReconUnitNum_t which_ru;
        int     nReadNodes, nPQNodes;
        RF_PhysDiskAddr_t *failedPDA = asmap->failedPDAs[0];
        RF_PhysDiskAddr_t *failedPDAtwo = asmap->failedPDAs[1];
        RF_StripeNum_t parityStripeID = rf_RaidAddressToParityStripeID(layoutPtr, asmap->raidAddress, &which_ru);

#if RF_DEBUG_DAG
        if (rf_dagDebug)
                printf("[Creating Double Degraded Read DAG]\n");
#endif
        rf_DD_GenerateFailedAccessASMs(raidPtr, asmap, &npdas, &nRrdNodes, &pqPDAs, &nPQNodes, allocList);

        nRudNodes = asmap->numStripeUnitsAccessed - (asmap->numDataFailed);
        nReadNodes = nRrdNodes + nRudNodes + 2 * nPQNodes;
        nNodes = 4 /* block, unblock, recovery, term */ + nReadNodes;

        nodes = RF_MallocAndAdd(nNodes * sizeof(*nodes), allocList);
        i = 0;
        blockNode = &nodes[i];
        i += 1;
        unblockNode = &nodes[i];
        i += 1;
        recoveryNode = &nodes[i];
        i += 1;
        termNode = &nodes[i];
        i += 1;
        rudNodes = &nodes[i];
        i += nRudNodes;
        rrdNodes = &nodes[i];
        i += nRrdNodes;
        rpNodes = &nodes[i];
        i += nPQNodes;
        rqNodes = &nodes[i];
        i += nPQNodes;
        RF_ASSERT(i == nNodes);

        dag_h->numSuccedents = 1;
        dag_h->succedents[0] = blockNode;
        dag_h->creator = "DoubleDegRead";
        dag_h->numCommits = 0;
        dag_h->numCommitNodes = 1;      /* unblock */

        rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc, rf_TerminateUndoFunc, NULL, 0, 2, 0, 0, dag_h, "Trm", allocList);
        termNode->antecedents[0] = unblockNode;
        termNode->antType[0] = rf_control;
        termNode->antecedents[1] = recoveryNode;
        termNode->antType[1] = rf_control;

        /* init the block and unblock nodes */
        /* The block node has all nodes except itself, unblock and recovery as
         * successors. Similarly for predecessors of the unblock. */
        rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc, NULL, nReadNodes, 0, 0, 0, dag_h, "Nil", allocList);
        rf_InitNode(unblockNode, rf_wait, RF_TRUE, rf_NullNodeFunc, rf_NullNodeUndoFunc, NULL, 1, nReadNodes, 0, 0, dag_h, "Nil", allocList);

        for (i = 0; i < nReadNodes; i++) {
                blockNode->succedents[i] = rudNodes + i;
                unblockNode->antecedents[i] = rudNodes + i;
                unblockNode->antType[i] = rf_control;
        }
        unblockNode->succedents[0] = termNode;

        /* The recovery node has all the reads as predecessors, and the term
         * node as successors. It gets a pda as a param from each of the read
         * nodes plus the raidPtr. For each failed unit is has a result pda. */
        rf_InitNode(recoveryNode, rf_wait, RF_FALSE, recovFunc, rf_NullNodeUndoFunc, NULL,
            1,                  /* succesors */
            nReadNodes,         /* preds */
            nReadNodes + 2,     /* params */
            asmap->numDataFailed,       /* results */
            dag_h, recoveryNodeName, allocList);

        recoveryNode->succedents[0] = termNode;
        for (i = 0; i < nReadNodes; i++) {
                recoveryNode->antecedents[i] = rudNodes + i;
                recoveryNode->antType[i] = rf_trueData;
        }

        /* build the read nodes, then come back and fill in recovery params
         * and results */
        pda = asmap->physInfo;
        for (i = 0; i < nRudNodes; pda = pda->next) {
                if ((pda == failedPDA) || (pda == failedPDAtwo))
                        continue;
                INIT_DISK_NODE(rudNodes + i, "Rud");
                RF_ASSERT(pda);
                DISK_NODE_PARAMS(rudNodes[i], pda);
                i++;
        }

        pda = npdas;
        for (i = 0; i < nRrdNodes; i++, pda = pda->next) {
                INIT_DISK_NODE(rrdNodes + i, "Rrd");
                RF_ASSERT(pda);
                DISK_NODE_PARAMS(rrdNodes[i], pda);
        }

        /* redundancy pdas */
        pda = pqPDAs;
        INIT_DISK_NODE(rpNodes, "Rp");
        RF_ASSERT(pda);
        DISK_NODE_PARAMS(rpNodes[0], pda);
        pda++;
        INIT_DISK_NODE(rqNodes, redundantReadNodeName);
        RF_ASSERT(pda);
        DISK_NODE_PARAMS(rqNodes[0], pda);
        if (nPQNodes == 2) {
                pda++;
                INIT_DISK_NODE(rpNodes + 1, "Rp");
                RF_ASSERT(pda);
                DISK_NODE_PARAMS(rpNodes[1], pda);
                pda++;
                INIT_DISK_NODE(rqNodes + 1, redundantReadNodeName);
                RF_ASSERT(pda);
                DISK_NODE_PARAMS(rqNodes[1], pda);
        }
        /* fill in recovery node params */
        for (i = 0; i < nReadNodes; i++)
                recoveryNode->params[i] = rudNodes[i].params[0];        /* pda */
        recoveryNode->params[i++].p = (void *) raidPtr;
        recoveryNode->params[i++].p = (void *) asmap;
        recoveryNode->results[0] = failedPDA;
        if (asmap->numDataFailed == 2)
                recoveryNode->results[1] = failedPDAtwo;

        /* zero fill the target data buffers? */
}

#endif /* (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0) || (RF_INCLUDE_EVENODD > 0) */