rf_parityloggingdags.c

RAIDFrame是个非常好的磁盘阵列RAID仿真工具

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

  /* initialize the redundancy node */
  rf_InitNode(xorNode, rf_wait, RF_TRUE, redFunc, rf_NullNodeUndoFunc, NULL, 1, 1, 2*(nWndNodes+nRodNodes)+1, 1, dag_h, "Xr ", allocList);
  xorNode->flags |= RF_DAGNODE_FLAG_YIELD;
  for (i=0; i < nWndNodes; i++) {
    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.
   */
  for (i = 0; i < nRodNodes; i++)
    if (((RF_PhysDiskAddr_t *) rodNodes[i].params[0].p)->numSector == raidPtr->Layout.sectorsPerStripeUnit)
      break;
  if (i == nRodNodes) {
    RF_CallocAndAdd(xorNode->results[0], 1, rf_RaidAddressToByte(raidPtr, raidPtr->Layout.sectorsPerStripeUnit), (void *), allocList);
  }
  else {
    xorNode->results[0] = rodNodes[i].params[1].p;
  }

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

  lpoNode->params[0].p = asmap->parityInfo;
  lpoNode->params[1].p = xorNode->results[0];
  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(dag_h->numSuccedents == 1);
  RF_ASSERT(blockNode->numAntecedents == 0);
  dag_h->succedents[0] = blockNode;

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

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

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

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

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

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

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

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

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




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

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

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

  /* DAG creation occurs in three steps:
     1. count the number of nodes in the DAG
     2. create the nodes
     3. initialize the nodes
     4. connect the nodes
   */

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

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

  nNodes     = numDataNodes + numParityNodes;

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

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

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

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

  /* initialize nodes which read old data (Rod) */
  for (i = 0; i < numDataNodes; i++) {
    rf_InitNode(&readDataNodes[i], rf_wait, RF_FALSE, rf_DiskReadFunc, rf_DiskReadUndoFunc, rf_GenericWakeupFunc, nNodes, 1, 4, 0, dag_h, "Rod", allocList);
    RF_ASSERT(pda != NULL);