dev/raidframe/rf_dagffrd.c

/*	$NetBSD: rf_dagffrd.c,v 1.2 1999/01/26 02:33:52 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 (at) 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_dagffrd.c
 *
 * code for creating fault-free read DAGs
 *
 */

#include "rf_types.h"
#include "rf_raid.h"
#include "rf_dag.h"
#include "rf_dagutils.h"
#include "rf_dagfuncs.h"
#include "rf_threadid.h"
#include "rf_debugMem.h"
#include "rf_memchunk.h"
#include "rf_general.h"
#include "rf_dagffrd.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_CreateFaultFreeReadDAG(
  RF_Raid_t             *raidPtr,
  RF_AccessStripeMap_t  *asmap,
  RF_DagHeader_t        *dag_h,
  void                  *bp,
  RF_RaidAccessFlags_t   flags,
  RF_AllocListElem_t    *allocList)
{
  rf_CreateNonredundantDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
    RF_IO_TYPE_READ);
}


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

/******************************************************************************
 *
 * creates a DAG to perform a nonredundant read or write of data within one
 * stripe.
 * For reads, this DAG is as follows:
 *
 *                   /---- read ----\
 *    Header -- Block ---- read ---- Commit -- Terminate
 *                   \---- read ----/
 *
 * For writes, this DAG is as follows:
 *
 *                    /---- write ----\
 *    Header -- Commit ---- write ---- Block -- Terminate
 *                    \---- write ----/
 *
 * There is one disk node per stripe unit accessed, and all disk nodes are in
 * parallel.
 *
 * Tricky point here:  The first disk node (read or write) is created
 * normally.  Subsequent disk nodes are created by copying the first one,
 * and modifying a few params.  The "succedents" and "antecedents" fields are
 * _not_ re-created in each node, but rather left pointing to the same array
 * that was malloc'd when the first node was created.  Thus, it's essential
 * that when this DAG is freed, the succedents and antecedents fields be freed
 * in ONLY ONE of the read nodes.  This does not apply to the "params" field
 * because it is recreated for each READ node.
 *
 * Note that normal-priority accesses do not need to be tagged with their
 * parity stripe ID, because they will never be promoted.  Hence, I've
 * commented-out the code to do this, and marked it with UNNEEDED.
 *
 *****************************************************************************/

void rf_CreateNonredundantDAG(
  RF_Raid_t             *raidPtr,
  RF_AccessStripeMap_t  *asmap,
  RF_DagHeader_t        *dag_h,
  void                  *bp,
  RF_RaidAccessFlags_t   flags,
  RF_AllocListElem_t    *allocList,
  RF_IoType_t            type)
{
  RF_DagNode_t *nodes, *diskNodes, *blockNode, *commitNode, *termNode;
  RF_PhysDiskAddr_t *pda = asmap->physInfo;
  int (*doFunc)(RF_DagNode_t *), (*undoFunc)(RF_DagNode_t *);
  int i, n, totalNumNodes;
  char *name;

  n = asmap->numStripeUnitsAccessed;
  dag_h->creator = "NonredundantDAG";

  RF_ASSERT(RF_IO_IS_R_OR_W(type));
  switch (type) {
    case RF_IO_TYPE_READ:
      doFunc = rf_DiskReadFunc;
      undoFunc = rf_DiskReadUndoFunc;
      name = "R  ";
      if (rf_dagDebug) printf("[Creating non-redundant read DAG]\n");
      break;
    case RF_IO_TYPE_WRITE:
      doFunc = rf_DiskWriteFunc;
      undoFunc = rf_DiskWriteUndoFunc;
      name = "W  ";
      if (rf_dagDebug) printf("[Creating non-redundant write DAG]\n");
      break;
    default:
      RF_PANIC();
  }

  /*
   * For reads, the dag can not commit until the block node is reached.
   * for writes, the dag commits immediately.
   */
  dag_h->numCommitNodes = 1;
  dag_h->numCommits = 0;
  dag_h->numSuccedents = 1;

  /*
   * Node count:
   * 1 block node
   * n data reads (or writes)
   * 1 commit node
   * 1 terminator node
   */
  RF_ASSERT(n > 0);
  totalNumNodes = n + 3;
  RF_CallocAndAdd(nodes, totalNumNodes, sizeof(RF_DagNode_t),
    (RF_DagNode_t *), allocList);
  i = 0;
  diskNodes   = &nodes[i]; i += n;
  blockNode   = &nodes[i]; i += 1;
  commitNode   = &nodes[i]; i += 1;
  termNode    = &nodes[i];  i += 1;
  RF_ASSERT(i == totalNumNodes);

  /* initialize nodes */
  switch (type) {
    case RF_IO_TYPE_READ:
      rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
        NULL, n, 0, 0, 0, dag_h, "Nil", allocList);
      rf_InitNode(commitNode, rf_wait, RF_TRUE, rf_NullNodeFunc, rf_NullNodeUndoFunc,
        NULL, 1, n, 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);
      break;
    case RF_IO_TYPE_WRITE:
      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, n, 1, 0, 0, dag_h, "Cmt", allocList);
      rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc, rf_TerminateUndoFunc,
        NULL, 0, n, 0, 0, dag_h, "Trm", allocList);
      break;
    default:
      RF_PANIC();
  }

  for (i = 0; i < n; i++) {
    RF_ASSERT(pda != NULL);
    rf_InitNode(&diskNodes[i], rf_wait, RF_FALSE, doFunc, undoFunc, rf_GenericWakeupFunc,
      1, 1, 4, 0, dag_h, name, allocList);
    diskNodes[i].params[0].p  = pda;
    diskNodes[i].params[1].p  = pda->bufPtr;
    /* parity stripe id is not necessary */
    diskNodes[i].params[2].v  = 0;
    diskNodes[i].params[3].v  = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, 0);
    pda = pda->next;
  }

  /*
   * Connect nodes.
   */

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

  if (type == RF_IO_TYPE_READ) {
    /* connecting a nonredundant read DAG */
    RF_ASSERT(blockNode->numSuccedents == n);
    RF_ASSERT(commitNode->numAntecedents == n);
    for (i=0; i < n; i++) {
      /* connect block node to each read node */
      RF_ASSERT(diskNodes[i].numAntecedents == 1);
      blockNode->succedents[i] = &diskNodes[i];
      diskNodes[i].antecedents[0] = blockNode;
      diskNodes[i].antType[0] = rf_control;

      /* connect each read node to the commit node */
      RF_ASSERT(diskNodes[i].numSuccedents == 1);
      diskNodes[i].succedents[0] = commitNode;
      commitNode->antecedents[i] = &diskNodes[i];
      commitNode->antType[i] = rf_control;
    }
    /* connect the commit node to the term node */
    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;
  }
  else {
    /* connecting a nonredundant write DAG */
    /* connect the block node to the commit node */
    RF_ASSERT(blockNode->numSuccedents == 1);
    RF_ASSERT(commitNode->numAntecedents == 1);
    blockNode->succedents[0] = commitNode;
    commitNode->antecedents[0] = blockNode;
    commitNode->antType[0] = rf_control;

    RF_ASSERT(commitNode->numSuccedents == n);
    RF_ASSERT(termNode->numAntecedents == n);
    RF_ASSERT(termNode->numSuccedents == 0);
    for (i=0; i < n; i++) {
      /* connect the commit node to each write node */
      RF_ASSERT(diskNodes[i].numAntecedents == 1);
      commitNode->succedents[i] = &diskNodes[i];
      diskNodes[i].antecedents[0] = commitNode;
      diskNodes[i].antType[0] = rf_control;

      /* connect each write node to the term node */
      RF_ASSERT(diskNodes[i].numSuccedents == 1);
      diskNodes[i].succedents[0] = termNode;
      termNode->antecedents[i] = &diskNodes[i];
      termNode->antType[i] = rf_control;
    }
  }
}

/******************************************************************************
 * Create a fault-free read DAG for RAID level 1
 *
 * Hdr -> Nil -> Rmir -> Cmt -> Trm
 *
 * The "Rmir" node schedules a read from the disk in the mirror pair with the
 * shortest disk queue.  the proper queue is selected at Rmir execution.  this
 * deferred mapping is unlike other archs in RAIDframe which generally fix
 * mapping at DAG creation time.
 *
 * Parameters:  raidPtr   - description of the physical array
 *              asmap     - logical & physical addresses for this access
 *              bp        - buffer ptr (for holding read data)
 *              flags     - general flags (e.g. disk locking)
 *              allocList - list of memory allocated in DAG creation
 *****************************************************************************/

static void CreateMirrorReadDAG(
  RF_Raid_t             *raidPtr,
  RF_AccessStripeMap_t  *asmap,
  RF_DagHeader_t        *dag_h,
  void                  *bp,
  RF_RaidAccessFlags_t   flags,
  RF_AllocListElem_t    *allocList,
  int                   (*readfunc)(RF_DagNode_t *node))
{
  RF_DagNode_t *readNodes, *nodes, *blockNode, *commitNode, *termNode;
  RF_PhysDiskAddr_t *data_pda = asmap->physInfo;
  RF_PhysDiskAddr_t *parity_pda = asmap->parityInfo;
  int i, n, totalNumNodes;

  n = asmap->numStripeUnitsAccessed;
  dag_h->creator = "RaidOneReadDAG";
  if (rf_dagDebug) {
    printf("[Creating RAID level 1 read DAG]\n");
  }

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

  /*
   * Node count:
   * n data reads
   * 1 block node
   * 1 commit node
   * 1 terminator node
   */
  RF_ASSERT(n > 0);
  totalNumNodes = n + 3;
  RF_CallocAndAdd(nodes, totalNumNodes, sizeof(RF_DagNode_t),
    (RF_DagNode_t *), allocList);
  i = 0;
  readNodes   = &nodes[i]; i += n;
  blockNode   = &nodes[i]; i += 1;
  commitNode = &nodes[i]; i += 1;
  termNode    = &nodes[i]; i += 1;
  RF_ASSERT(i == totalNumNodes);

  /* initialize nodes */
  rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc,
    rf_NullNodeUndoFunc, NULL, n, 0, 0, 0, dag_h, "Nil", allocList);
  rf_InitNode(commitNode, rf_wait, RF_TRUE, rf_NullNodeFunc,
    rf_NullNodeUndoFunc, NULL, 1, n, 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);

  for (i = 0; i < n; i++) {
    RF_ASSERT(data_pda != NULL);
    RF_ASSERT(parity_pda != NULL);
    rf_InitNode(&readNodes[i], rf_wait, RF_FALSE, readfunc,
      rf_DiskReadMirrorUndoFunc, rf_GenericWakeupFunc, 1, 1, 5, 0, dag_h,
      "Rmir", allocList);
    readNodes[i].params[0].p = data_pda;
    readNodes[i].params[1].p = data_pda->bufPtr;
    /* parity stripe id is not necessary */
    readNodes[i].params[2].p = 0;
    readNodes[i].params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, 0);
    readNodes[i].params[4].p = parity_pda;
    data_pda = data_pda->next;
    parity_pda = parity_pda->next;
  }

  /*
   * Connect nodes
   */

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

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

  /* connect read nodes to commit node */
  RF_ASSERT(commitNode->numAntecedents == n);
  for (i=0; i < n; i++) {
    RF_ASSERT(readNodes[i].numSuccedents == 1);
    readNodes[i].succedents[0] = commitNode;
    commitNode->antecedents[i] = &readNodes[i];
    commitNode->antType[i] = rf_control;
  }

  /* connect commit node to term node */
  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;
}

void rf_CreateMirrorIdleReadDAG(
  RF_Raid_t             *raidPtr,
  RF_AccessStripeMap_t  *asmap,
  RF_DagHeader_t        *dag_h,
  void                  *bp,
  RF_RaidAccessFlags_t   flags,
  RF_AllocListElem_t    *allocList)
{
  CreateMirrorReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
    rf_DiskReadMirrorIdleFunc);
}

void rf_CreateMirrorPartitionReadDAG(
  RF_Raid_t             *raidPtr,
  RF_AccessStripeMap_t  *asmap,
  RF_DagHeader_t        *dag_h,
  void                  *bp,
  RF_RaidAccessFlags_t   flags,
  RF_AllocListElem_t    *allocList)
{
  CreateMirrorReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
    rf_DiskReadMirrorPartitionFunc);
}