rf_dagffwr.c

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  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_FALSE, 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_FALSE, redFunc, rf_NullNodeUndoFunc, NULL, 1, nfaults, 2 * (nWndNodes + nRodNodes) + 1, nfaults, dag_h, "Xr ", allocList);
  xorNode->flags |= RF_DAGNODE_FLAG_YIELD;
  for (i=0; i < nWndNodes; i++) {
    xorNode->params[2*i+0] = wndNodes[i].params[0];         /* pda */
    xorNode->params[2*i+1] = wndNodes[i].params[1];         /* buf ptr */
  }
  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 */
  }
  xorNode->params[2*(nWndNodes+nRodNodes)].p = raidPtr; /* xor node needs to get at RAID information */
  
  /* 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.
   */
  if (allowBufferRecycle) {
    for (i = 0; i < nRodNodes; i++)
      if (((RF_PhysDiskAddr_t *) rodNodes[i].params[0].p)->numSector == raidPtr->Layout.sectorsPerStripeUnit)
        break;
  }
  if ((!allowBufferRecycle) || (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 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 = asmap->parityInfo;
  wnpNode->params[1].p = xorNode->results[0];
  wnpNode->params[2].v = parityStripeID;
  wnpNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, which_ru);
  RF_ASSERT(asmap->parityInfo->next == NULL);        /* parityInfo must describe entire parity unit */

  if (nfaults == 2)
    {
      /* we never try to recycle a buffer for the Q calcuation in addition to the parity.
	 This would cause two buffers to get smashed during the P and Q calculation, 
	 guaranteeing one would be wrong.
      */
      RF_CallocAndAdd(xorNode->results[1], 1, rf_RaidAddressToByte(raidPtr, raidPtr->Layout.sectorsPerStripeUnit), (void *), allocList); 
      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 = asmap->qInfo;
      wnqNode->params[1].p = xorNode->results[1];
      wnqNode->params[2].v = parityStripeID;
      wnqNode->params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, which_ru);
      RF_ASSERT(asmap->parityInfo->next == NULL);        /* parityInfo must describe entire parity unit */
    }


  /* connect nodes to form graph */

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

  if (nRodNodes > 0) {
    /* connect the block node to the Rod nodes */
    RF_ASSERT(blockNode->numSuccedents == nRodNodes);
    RF_ASSERT(syncNode->numAntecedents == nRodNodes);
    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 Rod nodes to the Nil node */
      RF_ASSERT(rodNodes[i].numSuccedents == 1);
      rodNodes[i].succedents[0] = syncNode;
      syncNode->antecedents[i] = &rodNodes[i];
      syncNode->antType[i] = rf_trueData;
    }
  }
  else {
    /* connect the block node to the Nil node */
    RF_ASSERT(blockNode->numSuccedents == 1);
    RF_ASSERT(syncNode->numAntecedents == 1);
    blockNode->succedents[0] = syncNode;
    syncNode->antecedents[0] = blockNode;
    syncNode->antType[0] = rf_control;
  }

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

  /* connect the sync node to the Xor node */
  RF_ASSERT(xorNode->numAntecedents == 1);
  syncNode->succedents[nWndNodes] = xorNode;
  xorNode->antecedents[0] = syncNode;
  xorNode->antType[0] = rf_control;

  /* connect the xor node to the write parity node */
  RF_ASSERT(xorNode->numSuccedents == nfaults);
  RF_ASSERT(wnpNode->numAntecedents == 1);
  xorNode->succedents[0] = wnpNode;
  wnpNode->antecedents[0]= xorNode;
  wnpNode->antType[0] = rf_trueData;
  if (nfaults == 2) {
    RF_ASSERT(wnqNode->numAntecedents == 1);
    xorNode->succedents[1] = wnqNode;
    wnqNode->antecedents[0] = xorNode;
    wnqNode->antType[0] = rf_trueData;
  }

  /* connect the write nodes to the term node */
  RF_ASSERT(termNode->numAntecedents == nWndNodes + nfaults);
  RF_ASSERT(termNode->numSuccedents == 0);
  for (i = 0; i < nWndNodes; i++) {
    RF_ASSERT(wndNodes->numSuccedents == 1);
    wndNodes[i].succedents[0] = termNode;
    termNode->antecedents[i] = &wndNodes[i];
    termNode->antType[i] = rf_control;
  }
  RF_ASSERT(wnpNode->numSuccedents == 1);
  wnpNode->succedents[0] = termNode;
  termNode->antecedents[nWndNodes] = wnpNode;
  termNode->antType[nWndNodes] = rf_control;
  if (nfaults == 2) {
    RF_ASSERT(wnqNode->numSuccedents == 1);
    wnqNode->succedents[0] = termNode;
    termNode->antecedents[nWndNodes + 1] = wnqNode;
    termNode->antType[nWndNodes + 1] = rf_control;
  }
}


/******************************************************************************
 *
 * creates a DAG to perform a small-write operation (either raid 5 or pq),
 * which is as follows:
 *
 * Hdr -> Nil -> Rop - Xor - Wnp [Unp] -- Trm
 *            \- Rod X- Wnd [Und] -------/
 *           [\- Rod X- Wnd [Und] ------/]
 *           [\- Roq - Q --> Wnq [Unq]-/]
 *
 * Rop = read old parity
 * Rod = read old data
 * Roq = read old "q"
 * Cmt = commit node
 * Und = unlock data disk
 * Unp = unlock parity disk
 * Unq = unlock q disk
 * Wnp = write new parity
 * Wnd = write new data
 * Wnq = write new "q"
 * [ ] denotes optional segments in the graph
 *
 * Parameters:  raidPtr   - description of the physical array
 *              asmap     - logical & physical addresses for this access
 *              bp        - buffer ptr (holds write data)
 *              flags     - general flags (e.g. disk locking) 
 *              allocList - list of memory allocated in DAG creation
 *              pfuncs    - list of parity generating functions
 *              qfuncs    - list of q generating functions
 *
 * A null qfuncs indicates single fault tolerant
 *****************************************************************************/

void rf_CommonCreateSmallWriteDAGFwd(
  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 *readDataNodes, *readParityNodes, *readQNodes, *termNode;
  RF_DagNode_t *unlockDataNodes, *unlockParityNodes, *unlockQNodes;
  RF_DagNode_t *xorNodes, *qNodes, *blockNode, *nodes;
  RF_DagNode_t *writeDataNodes, *writeParityNodes, *writeQNodes;
  int i, j, nNodes, totalNumNodes, lu_flag;
  RF_ReconUnitNum_t which_ru;
  int (*func)(), (*undoFunc)(), (*qfunc)();
  int numDataNodes, numParityNodes;
  RF_StripeNum_t parityStripeID;
  RF_PhysDiskAddr_t *pda;
  char *name, *qname;
  long nfaults;

  nfaults = qfuncs ? 2 : 1;
  lu_flag = (rf_enableAtomicRMW) ? 1 : 0;          /* lock/unlock flag */

  parityStripeID = rf_RaidAddressToParityStripeID(&(raidPtr->Layout), asmap->raidAddress, &which_ru);
  pda = asmap->physInfo;
  numDataNodes = asmap->numStripeUnitsAccessed;
  numParityNodes = (asmap->parityInfo->next) ? 2 : 1;

  if (rf_dagDebug) printf("[Creating small-write DAG]\n");
  RF_ASSERT(numDataNodes > 0);
  dag_h->creator = "SmallWriteDAGFwd";

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

  qfunc = NULL;
  qname = NULL;

  /* DAG creation occurs in four 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 (nfaults * nparity)
      a read and write for each parity unit
      a block node
      a terminate node
      if atomic RMW
        an unlock node for each data unit, redundancy unit
  */
  totalNumNodes = (2 * numDataNodes) + (nfaults * numParityNodes) + (nfaults * 2 * numParityNodes) + 2;
  if (lu_flag)
    totalNumNodes += (numDataNodes + (nfaults * numParityNodes));


  /* Step 2. create the nodes */
  RF_CallocAndAdd(nodes, totalNumNodes, sizeof(RF_DagNode_t), (RF_DagNode_t *), allocList);
  i = 0;
  blockNode        = &nodes[i]; i += 1;
  readDataNodes    = &nodes[i]; i += numDataNodes;
  readParityNodes  = &nodes[i]; i += numParityNodes;
  writeDataNodes   = &nodes[i]; i += numDataNodes;
  writeParityNodes = &nodes[i]; i += numParityNodes;
  xorNodes         = &nodes[i]; i += numParityNodes;
  termNode         = &nodes[i]; i += 1;
  if (lu_flag) {
    unlockDataNodes   = &nodes[i]; i += numDataNodes;
    unlockParityNodes = &nodes[i]; i += numParityNodes;
  }
  else {
    unlockDataNodes = unlockParityNodes = NULL;
  }
  if (nfaults == 2) {
    readQNodes     = &nodes[i]; i += numParityNodes;
    writeQNodes    = &nodes[i]; i += numParityNodes;
    qNodes         = &nodes[i]; i += numParityNodes;
    if (lu_flag) {
      unlockQNodes    = &nodes[i]; i += numParityNodes;
    }
    else {
      unlockQNodes = NULL;
    }
  }
  else {
    readQNodes = writeQNodes = qNodes = unlockQNodes = NULL;
  }
  RF_ASSERT(i == totalNumNodes);
  
  /* Step 3. initialize the nodes */
  /* initialize block node (Nil) */
  nNodes     = numDataNodes + (nfaults * numParityNodes);
  rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc, NULL, nNodes, 0, 0, 0, dag_h, "Nil", allocList);

  /* initialize terminate node (Trm) */
  rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc, rf_TerminateUndoFunc, NULL, 0, nNodes, 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, (numParityNodes * nfaults) + 1, 1, 4, 0, dag_h, "Rod", allocList);
    RF_ASSERT(pda != NULL);
    readDataNodes[i].params[0].p = pda;  /* physical disk addr desc */
    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;
    for (j = 0; j < readDataNodes[i].numSuccedents; j++)
      readDataNodes[i].propList[j] = 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, numParityNodes, 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, lu_flag, 0, which_ru);
    for (j = 0; j < readParityNodes[i].numSuccedents; j++)
      readParityNodes[i].propList[0] = NULL;
    pda=pda->next;
  }

  /* initialize nodes which read old Q (Roq) */
  if (nfaults == 2)
    {
      pda = asmap->qInfo; 
      for (i = 0; i < numParityNodes; i++) {
	RF_ASSERT(pda != NULL);
	rf_InitNode(&readQNodes[i], rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc, rf_GenericWakeupFunc, numParityNodes, 1, 4, 0, dag_h, "Roq", allocList);
	readQNodes[i].params[0].p = pda;
	readQNodes[i].params[1].p = rf_AllocBuffer(raidPtr, dag_h, pda, allocList); /* buffer to hold old Q */
	readQNodes[i].params[2].v = parityStripeID;
	readQNodes[i].params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, lu_flag, 0, which_ru);
	for (j = 0; j < readQNodes[i].numSuccedents; j++)
	  readQNodes[i].propList[0] = NULL;
	pda=pda->next;
      }
    }