/*      $NetBSD: rf_dagdegwr.c,v 1.37 2023/10/15 18:15:19 oster 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_dagdegwr.c
 *
 * code for creating degraded write DAGs
 *
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rf_dagdegwr.c,v 1.37 2023/10/15 18:15:19 oster Exp $");

#include <dev/raidframe/raidframevar.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_dagdegwr.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.
 */

static
RF_CREATE_DAG_FUNC_DECL(rf_CreateSimpleDegradedWriteDAG)
{
        rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp,
            flags, allocList, 1, rf_RecoveryXorFunc, RF_TRUE);
}

void
rf_CreateDegradedWriteDAG(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asmap,
                          RF_DagHeader_t *dag_h, void *bp,
                          RF_RaidAccessFlags_t flags,
                          RF_AllocListElem_t *allocList)
{

        RF_ASSERT(asmap->numDataFailed == 1);
        dag_h->creator = "DegradedWriteDAG";

        /*
         * if the access writes only a portion of the failed unit, and also
         * writes some portion of at least one surviving unit, we create two
         * DAGs, one for the failed component and one for the non-failed
         * component, and do them sequentially.  Note that the fact that we're
         * accessing only a portion of the failed unit indicates that the
         * access either starts or ends in the failed unit, and hence we need
         * create only two dags.  This is inefficient in that the same data or
         * parity can get read and written twice using this structure.  I need
         * to fix this to do the access all at once.
         */
        RF_ASSERT(!(asmap->numStripeUnitsAccessed != 1 &&
                    asmap->failedPDAs[0]->numSector !=
                        raidPtr->Layout.sectorsPerStripeUnit));
        rf_CreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp, flags,
            allocList);
}



/******************************************************************************
 *
 * DAG creation code begins here
 */
#define BUF_ALLOC(num) \
  RF_MallocAndAdd(rf_RaidAddressToByte(raidPtr, num), allocList)



/******************************************************************************
 *
 * CommonCreateSimpleDegradedWriteDAG -- creates a DAG to do a degraded-mode
 * write, which is as follows
 *
 *                                        / {Wnq} --\
 * hdr -> blockNode ->  Rod -> Xor -> Cmt -> Wnp ----> unblock -> term
 *                  \  {Rod} /            \  Wnd ---/
 *                                        \ {Wnd} -/
 *
 * commit nodes: Xor, Wnd
 *
 * IMPORTANT:
 * This DAG generator does not work for double-degraded archs since it does not
 * generate Q
 *
 * This dag is essentially identical to the large-write dag, except that the
 * write to the failed data unit is suppressed.
 *
 * IMPORTANT:  this dag does not work in the case where the access writes only
 * a portion of the failed unit, and also writes some portion of at least one
 * surviving SU.  this case is handled in CreateDegradedWriteDAG above.
 *
 * The block & unblock nodes are leftovers from a previous version.  They
 * do nothing, but I haven't deleted them because it would be a tremendous
 * effort to put them back in.
 *
 * This dag is used whenever a one of the data units in a write has failed.
 * If it is the parity unit that failed, the nonredundant write dag (below)
 * is used.
 *****************************************************************************/

void
rf_CommonCreateSimpleDegradedWriteDAG(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,
                                      void (*redFunc) (RF_DagNode_t *),
                                      int allowBufferRecycle)
{
        int     nRrdNodes, nWndNodes, nXorBufs, i, j, paramNum,
                rdnodesFaked;
        RF_DagNode_t *blockNode, *unblockNode, *wnpNode, *termNode;
#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
        RF_DagNode_t *wnqNode;
#endif
        RF_DagNode_t *wndNodes, *rrdNodes, *xorNode, *commitNode;
        RF_DagNode_t *tmpNode, *tmpwndNode, *tmprrdNode;
        RF_SectorCount_t sectorsPerSU;
        RF_ReconUnitNum_t which_ru;
        char   *xorTargetBuf = NULL;    /* the target buffer for the XOR
                                         * operation */
        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;

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

#if RF_DEBUG_DAG
        if (rf_dagDebug)
                printf("[Creating degraded-write DAG]\n");
#endif

        RF_ASSERT(asmap->numDataFailed == 1);
        dag_h->creator = "SimpleDegradedWriteDAG";

        /*
         * 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, NULL, overlappingPDAs, allocList);

        /* create all the nodes at once */
        nWndNodes = asmap->numStripeUnitsAccessed - 1;  /* no access is
                                                         * generated for the
                                                         * failed pda */

        nRrdNodes = ((new_asm_h[0]) ? new_asm_h[0]->stripeMap->numStripeUnitsAccessed : 0) +
            ((new_asm_h[1]) ? new_asm_h[1]->stripeMap->numStripeUnitsAccessed : 0);
        /*
         * XXX
         *
         * There's a bug with a complete stripe overwrite- that means 0 reads
         * of old data, and the rest of the DAG generation code doesn't like
         * that. A release is coming, and I don't wanna risk breaking a critical
         * DAG generator, so here's what I'm gonna do- if there's no read nodes,
         * I'm gonna fake there being a read node, and I'm gonna swap in a
         * no-op node in its place (to make all the link-up code happy).
         * This should be fixed at some point.  --jimz
         */
        if (nRrdNodes == 0) {
                nRrdNodes = 1;
                rdnodesFaked = 1;
        } else {
                rdnodesFaked = 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;

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

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

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

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

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

#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
        if (nfaults == 2) {
                wnqNode = rf_AllocDAGNode(raidPtr);
                wnqNode->list_next = dag_h->nodes;
                dag_h->nodes = wnqNode;
        } else {
                wnqNode = NULL;
        }
#endif

        /* this dag can not commit until all rrd and xor Nodes have completed */
        dag_h->numCommitNodes = 1;
        dag_h->numCommits = 0;
        dag_h->numSuccedents = 1;

        RF_ASSERT(nRrdNodes > 0);
        rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, nRrdNodes, 0, 0, 0, dag_h, "Nil", allocList);
        rf_InitNode(commitNode, rf_wait, RF_TRUE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, nWndNodes + nfaults, 1, 0, 0, dag_h, "Cmt", allocList);
        rf_InitNode(unblockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
            NULL, 1, nWndNodes + nfaults, 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);
        rf_InitNode(xorNode, rf_wait, RF_FALSE, redFunc, rf_NullNodeUndoFunc, NULL, 1,
            nRrdNodes, 2 * nXorBufs + 2, nfaults, dag_h, "Xrc", allocList);

        /*
         * Fill in the Rrd nodes. If any of the rrd buffers are the same size as
         * the failed buffer, save a pointer to it so we can use it as the target
         * of the XOR. The pdas in the rrd nodes have been range-restricted, so if
         * a buffer is the same size as the failed buffer, it must also be at the
         * same alignment within the SU.
         */
        i = 0;
        tmprrdNode = rrdNodes;
        if (new_asm_h[0]) {
                for (i = 0, 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;
                }
        }
        /* i now equals the number of stripe units accessed in new_asm_h[0] */
        /* Note that for tmprrdNode, this means a continuation from above, so no need to
           assign it anything.. */
        if (new_asm_h[1]) {
                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);
                        if (allowBufferRecycle && (pda->numSector == failedPDA->numSector))
                                xorTargetBuf = pda->bufPtr;
                        tmprrdNode = tmprrdNode->list_next;
                }
        }
        if (rdnodesFaked) {
                /*
                 * This is where we'll init that fake noop read node
                 * (XXX should the wakeup func be different?)
                 */
                /* node that rrdNodes will just be a single node... */
                rf_InitNode(rrdNodes, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
                    NULL, 1, 1, 0, 0, dag_h, "RrN", allocList);
        }
        /*
         * Make a PDA for the parity unit.  The parity PDA should start at
         * the same offset into the SU as the failed PDA.
         */
        /* Danner comment: I don't think this copy is really necessary. We are
         * in one of two cases here. (1) The entire failed unit is written.
         * Then asmap->parityInfo will describe the entire parity. (2) We are
         * only writing a subset of the failed unit and nothing else. Then the
         * asmap->parityInfo describes the failed unit and the copy can also
         * be avoided. */

        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;

        if (!xorTargetBuf) {
                xorTargetBuf = rf_AllocBuffer(raidPtr, dag_h, rf_RaidAddressToByte(raidPtr, failedPDA->numSector));
        }
        /* init the Wnp node */
        rf_InitNode(wnpNode, rf_wait, RF_FALSE, rf_DiskWriteFunc, rf_DiskWriteUndoFunc,
            rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, "Wnp", allocList);
        wnpNode->params[0].p = parityPDA;
        wnpNode->params[1].p = xorTargetBuf;
        wnpNode->params[2].v = parityStripeID;
        wnpNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);

#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
        /* fill in the Wnq Node */
        if (nfaults == 2) {
                {
                        parityPDA = RF_MallocAndAdd(sizeof(*parityPDA), allocList);
                        parityPDA->col = asmap->qInfo->col;
                        parityPDA->startSector = ((asmap->qInfo->startSector / sectorsPerSU)
                            * sectorsPerSU) + (failedPDA->startSector % sectorsPerSU);
                        parityPDA->numSector = failedPDA->numSector;

                        rf_InitNode(wnqNode, rf_wait, RF_FALSE, rf_DiskWriteFunc, rf_DiskWriteUndoFunc,
                            rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, "Wnq", allocList);
                        wnqNode->params[0].p = parityPDA;
                        xorNode->results[1] = BUF_ALLOC(failedPDA->numSector);
                        wnqNode->params[1].p = xorNode->results[1];
                        wnqNode->params[2].v = parityStripeID;
                        wnqNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);
                }
        }
#endif
        /* fill in the Wnd nodes */
        tmpwndNode = wndNodes;
        for (pda = asmap->physInfo, i = 0; i < nWndNodes; i++, pda = pda->next) {
                if (pda == failedPDA) {
                        i--;
                        continue;
                }
                rf_InitNode(tmpwndNode, rf_wait, RF_FALSE, rf_DiskWriteFunc, rf_DiskWriteUndoFunc,
                    rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, "Wnd", allocList);
                RF_ASSERT(pda);
                tmpwndNode->params[0].p = pda;
                tmpwndNode->params[1].p = pda->bufPtr;
                tmpwndNode->params[2].v = parityStripeID;
                tmpwndNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, which_ru);
                tmpwndNode = tmpwndNode->list_next;
        }

        /* fill in the results of the xor node */
        xorNode->results[0] = xorTargetBuf;

        /* fill in the params of the xor node */

        paramNum = 0;
        if (rdnodesFaked == 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;
                }
        }
        tmpwndNode = wndNodes;
        for (i = 0; i < nWndNodes; i++) {
                /* any Wnd nodes that overlap the failed access need to be
                 * xored in */
                if (overlappingPDAs[i]) {
                        pda = rf_AllocPhysDiskAddr(raidPtr);
                        memcpy((char *) pda, (char *) tmpwndNode->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;
                }
                tmpwndNode = tmpwndNode->list_next;
        }

        /*
         * Install the failed PDA into the xor param list so that the
         * new data gets xor'd in.
         */
        xorNode->params[paramNum++].p = failedPDA;
        xorNode->params[paramNum++].p = failedPDA->bufPtr;

        /*
         * The last 2 params to the recovery xor node are always the failed
         * PDA and the raidPtr. install the failedPDA even though we have just
         * done so above. This allows us to use the same XOR function for both
         * degraded reads and degraded writes.
         */
        xorNode->params[paramNum++].p = failedPDA;
        xorNode->params[paramNum++].p = raidPtr;
        RF_ASSERT(paramNum == 2 * nXorBufs + 2);

        /*
         * Code to link nodes begins here
         */

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

        /* link block node to rd nodes */
        RF_ASSERT(blockNode->numSuccedents == nRrdNodes);
        tmprrdNode = rrdNodes;
        for (i = 0; i < nRrdNodes; i++) {
                RF_ASSERT(tmprrdNode->numAntecedents == 1);
                blockNode->succedents[i] = tmprrdNode;
                tmprrdNode->antecedents[0] = blockNode;
                tmprrdNode->antType[0] = rf_control;
                tmprrdNode = tmprrdNode->list_next;
        }

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

        /* link xor node to 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;

        /* link commit node to wnd nodes */
        RF_ASSERT(commitNode->numSuccedents == nfaults + nWndNodes);
        tmpwndNode = wndNodes;
        for (i = 0; i < nWndNodes; i++) {
                RF_ASSERT(tmpwndNode->numAntecedents == 1);
                commitNode->succedents[i] = tmpwndNode;
                tmpwndNode->antecedents[0] = commitNode;
                tmpwndNode->antType[0] = rf_control;
                tmpwndNode = tmpwndNode->list_next;
        }

        /* link the commit node to wnp, wnq nodes */
        RF_ASSERT(wnpNode->numAntecedents == 1);
        commitNode->succedents[nWndNodes] = wnpNode;
        wnpNode->antecedents[0] = commitNode;
        wnpNode->antType[0] = rf_control;
#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
        if (nfaults == 2) {
                RF_ASSERT(wnqNode->numAntecedents == 1);
                commitNode->succedents[nWndNodes + 1] = wnqNode;
                wnqNode->antecedents[0] = commitNode;
                wnqNode->antType[0] = rf_control;
        }
#endif
        /* link write new data nodes to unblock node */
        RF_ASSERT(unblockNode->numAntecedents == (nWndNodes + nfaults));
        tmpwndNode = wndNodes;
        for (i = 0; i < nWndNodes; i++) {
                RF_ASSERT(tmpwndNode->numSuccedents == 1);
                tmpwndNode->succedents[0] = unblockNode;
                unblockNode->antecedents[i] = tmpwndNode;
                unblockNode->antType[i] = rf_control;
                tmpwndNode = tmpwndNode->list_next;
        }

        /* link write new parity node to unblock node */
        RF_ASSERT(wnpNode->numSuccedents == 1);
        wnpNode->succedents[0] = unblockNode;
        unblockNode->antecedents[nWndNodes] = wnpNode;
        unblockNode->antType[nWndNodes] = rf_control;

#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
        /* link write new q node to unblock node */
        if (nfaults == 2) {
                RF_ASSERT(wnqNode->numSuccedents == 1);
                wnqNode->succedents[0] = unblockNode;
                unblockNode->antecedents[nWndNodes + 1] = wnqNode;
                unblockNode->antType[nWndNodes + 1] = rf_control;
        }
#endif
        /* link unblock node to term node */
        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;
}
#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 (RF_INCLUDE_RAID6 > 0) || (RF_INCLUDE_PQ > 0) || (RF_INCLUDE_EVENODD > 0)
void
rf_WriteGenerateFailedAccessASMs(
    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;
        unsigned napdas;
        RF_SectorNum_t fone_start, ftwo_start = 0;
        RF_PhysDiskAddr_t *fone = asmap->failedPDAs[0], *ftwo = asmap->failedPDAs[1];
        RF_PhysDiskAddr_t *pda_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);

        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);
                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 - 2);
        *nPQNodep = PDAPerDisk;

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

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

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

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

        sosAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr, asmap->raidAddress);
        for (i = 0; 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 DISK_NODE_PDA(node)  ((node)->params[0].p)

#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_DoubleDegSmallWrite(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 *redundantWriteNodeName,
                       const char *recoveryNodeName,
                       void (*recovFunc) (RF_DagNode_t *))
{
        RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
        RF_DagNode_t *nodes, *wudNodes, *rrdNodes, *recoveryNode, *blockNode,
               *unblockNode, *rpNodes, *rqNodes, *wpNodes, *wqNodes, *termNode;
        RF_PhysDiskAddr_t *pda, *pqPDAs;
        RF_PhysDiskAddr_t *npdas;
        int     nWriteNodes, nNodes, nReadNodes, nRrdNodes, nWudNodes, i;
        RF_ReconUnitNum_t which_ru;
        int     nPQNodes;
        RF_StripeNum_t parityStripeID = rf_RaidAddressToParityStripeID(layoutPtr, asmap->raidAddress, &which_ru);

        /* simple small write case - First part looks like a reconstruct-read
         * of the failed data units. Then a write of all data units not
         * failed. */


        /* Hdr | ------Block- /  /         \   Rrd  Rrd ...  Rrd  Rp Rq \  \
         * /  -------PQ----- /   \   \ Wud   Wp  WQ          \    |   /
         * --Unblock- | T
         *
         * Rrd = read recovery data  (potentially none) Wud = write user data
         * (not incl. failed disks) Wp = Write P (could be two) Wq = Write Q
         * (could be two)
         *
         */

        rf_WriteGenerateFailedAccessASMs(raidPtr, asmap, &npdas, &nRrdNodes, &pqPDAs, &nPQNodes, allocList);

        RF_ASSERT(asmap->numDataFailed == 1);

        nWudNodes = asmap->numStripeUnitsAccessed - (asmap->numDataFailed);
        nReadNodes = nRrdNodes + 2 * nPQNodes;
        nWriteNodes = nWudNodes + 2 * nPQNodes;
        nNodes = 4 + nReadNodes + nWriteNodes;

        nodes = RF_MallocAndAdd(nNodes * sizeof(*nodes), allocList);
        blockNode = nodes;
        unblockNode = blockNode + 1;
        termNode = unblockNode + 1;
        recoveryNode = termNode + 1;
        rrdNodes = recoveryNode + 1;
        rpNodes = rrdNodes + nRrdNodes;
        rqNodes = rpNodes + nPQNodes;
        wudNodes = rqNodes + nPQNodes;
        wpNodes = wudNodes + nWudNodes;
        wqNodes = wpNodes + nPQNodes;

        dag_h->creator = "PQ_DDSimpleSmallWrite";
        dag_h->numSuccedents = 1;
        dag_h->succedents[0] = blockNode;
        rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc, rf_TerminateUndoFunc, NULL, 0, 1, 0, 0, dag_h, "Trm", allocList);
        termNode->antecedents[0] = unblockNode;
        termNode->antType[0] = rf_control;

        /* init the block and unblock nodes */
        /* The block node has all the read nodes as successors */
        rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc, NULL, nReadNodes, 0, 0, 0, dag_h, "Nil", allocList);
        for (i = 0; i < nReadNodes; i++)
                blockNode->succedents[i] = rrdNodes + i;

        /* The unblock node has all the writes as successors */
        rf_InitNode(unblockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc, NULL, 1, nWriteNodes, 0, 0, dag_h, "Nil", allocList);
        for (i = 0; i < nWriteNodes; i++) {
                unblockNode->antecedents[i] = wudNodes + i;
                unblockNode->antType[i] = rf_control;
        }
        unblockNode->succedents[0] = termNode;

#define INIT_READ_NODE(node,name) \
  rf_InitNode(node, rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc, rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, name, allocList); \
  (node)->succedents[0] = recoveryNode; \
  (node)->antecedents[0] = blockNode; \
  (node)->antType[0] = rf_control;

        /* build the read nodes */
        pda = npdas;
        for (i = 0; i < nRrdNodes; i++, pda = pda->next) {
                INIT_READ_NODE(rrdNodes + i, "rrd");
                DISK_NODE_PARAMS(rrdNodes[i], pda);
        }

        /* read redundancy pdas */
        pda = pqPDAs;
        INIT_READ_NODE(rpNodes, "Rp");
        RF_ASSERT(pda);
        DISK_NODE_PARAMS(rpNodes[0], pda);
        pda++;
        INIT_READ_NODE(rqNodes, redundantReadNodeName);
        RF_ASSERT(pda);
        DISK_NODE_PARAMS(rqNodes[0], pda);
        if (nPQNodes == 2) {
                pda++;
                INIT_READ_NODE(rpNodes + 1, "Rp");
                RF_ASSERT(pda);
                DISK_NODE_PARAMS(rpNodes[1], pda);
                pda++;
                INIT_READ_NODE(rqNodes + 1, redundantReadNodeName);
                RF_ASSERT(pda);
                DISK_NODE_PARAMS(rqNodes[1], pda);
        }
        /* the recovery node has all reads as precedessors and all writes as
         * successors. It generates a result for every write P or write Q
         * node. As parameters, it takes a pda per read and a pda per stripe
         * of user data written. It also takes as the last params the raidPtr
         * and asm. For results, it takes PDA for P & Q. */


        rf_InitNode(recoveryNode, rf_wait, RF_FALSE, recovFunc, rf_NullNodeUndoFunc, NULL,
            nWriteNodes,        /* succesors */
            nReadNodes,         /* preds */
            nReadNodes + nWudNodes + 3, /* params */
            2 * nPQNodes,       /* results */
            dag_h, recoveryNodeName, allocList);



        for (i = 0; i < nReadNodes; i++) {
                recoveryNode->antecedents[i] = rrdNodes + i;
                recoveryNode->antType[i] = rf_control;
                recoveryNode->params[i].p = DISK_NODE_PDA(rrdNodes + i);
        }
        for (i = 0; i < nWudNodes; i++) {
                recoveryNode->succedents[i] = wudNodes + i;
        }
        recoveryNode->params[nReadNodes + nWudNodes].p = asmap->failedPDAs[0];
        recoveryNode->params[nReadNodes + nWudNodes + 1].p = raidPtr;
        recoveryNode->params[nReadNodes + nWudNodes + 2].p = asmap;

        for (; i < nWriteNodes; i++)
                recoveryNode->succedents[i] = wudNodes + i;

        pda = pqPDAs;
        recoveryNode->results[0] = pda;
        pda++;
        recoveryNode->results[1] = pda;
        if (nPQNodes == 2) {
                pda++;
                recoveryNode->results[2] = pda;
                pda++;
                recoveryNode->results[3] = pda;
        }
        /* fill writes */
#define INIT_WRITE_NODE(node,name) \
  rf_InitNode(node, rf_wait, RF_FALSE, rf_DiskWriteFunc, rf_DiskWriteUndoFunc, rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, name, allocList); \
    (node)->succedents[0] = unblockNode; \
    (node)->antecedents[0] = recoveryNode; \
    (node)->antType[0] = rf_control;

        pda = asmap->physInfo;
        for (i = 0; i < nWudNodes; i++) {
                INIT_WRITE_NODE(wudNodes + i, "Wd");
                DISK_NODE_PARAMS(wudNodes[i], pda);
                recoveryNode->params[nReadNodes + i].p = DISK_NODE_PDA(wudNodes + i);
                pda = pda->next;
        }
        /* write redundancy pdas */
        pda = pqPDAs;
        INIT_WRITE_NODE(wpNodes, "Wp");
        RF_ASSERT(pda);
        DISK_NODE_PARAMS(wpNodes[0], pda);
        pda++;
        INIT_WRITE_NODE(wqNodes, "Wq");
        RF_ASSERT(pda);
        DISK_NODE_PARAMS(wqNodes[0], pda);
        if (nPQNodes == 2) {
                pda++;
                INIT_WRITE_NODE(wpNodes + 1, "Wp");
                RF_ASSERT(pda);
                DISK_NODE_PARAMS(wpNodes[1], pda);
                pda++;
                INIT_WRITE_NODE(wqNodes + 1, "Wq");
                RF_ASSERT(pda);
                DISK_NODE_PARAMS(wqNodes[1], pda);
        }
}
#endif   /* (RF_INCLUDE_PQ > 0) || (RF_INCLUDE_EVENODD > 0) */