rf_dagffrd.c

RAIDFrame是个非常好的磁盘阵列RAID仿真工具

/*
 * 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  [e-mail]
 *  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
 *
 * $Locker:  $
 * $Log: rf_dagffrd.c,v $
 * Revision 1.14  1996/07/28  20:31:39  jimz
 * i386netbsd port
 * true/false fixup
 *
 * Revision 1.13  1996/07/22  19:52:16  jimz
 * switched node params to RF_DagParam_t, a union of
 * a 64-bit int and a void *, for better portability
 * attempted hpux port, but failed partway through for
 * lack of a single C compiler capable of compiling all
 * source files
 *
 * Revision 1.12  1996/06/09  02:36:46  jimz
 * lots of little crufty cleanup- fixup whitespace
 * issues, comment #ifdefs, improve typing in some
 * places (esp size-related)
 *
 * Revision 1.11  1996/06/06  17:30:44  jimz
 * turn old Raid1 mirror read creation into a more generic function
 * parameterized by an addtional parameter: type of mirrored read
 * this is now used by other dag creation routines so chained declustering
 * and raid1 can share dag creation code, but have different mirroring
 * policies
 *
 * Revision 1.10  1996/05/31  22:26:54  jimz
 * fix a lot of mapping problems, memory allocation problems
 * found some weird lock issues, fixed 'em
 * more code cleanup
 *
 * Revision 1.9  1996/05/30  11:29:41  jimz
 * Numerous bug fixes. Stripe lock release code disagreed with the taking code
 * about when stripes should be locked (I made it consistent: no parity, no lock)
 * There was a lot of extra serialization of I/Os which I've removed- a lot of
 * it was to calculate values for the cache code, which is no longer with us.
 * More types, function, macro cleanup. Added code to properly quiesce the array
 * on shutdown. Made a lot of stuff array-specific which was (bogusly) general
 * before. Fixed memory allocation, freeing bugs.
 *
 * Revision 1.8  1996/05/27  18:56:37  jimz
 * more code cleanup
 * better typing
 * compiles in all 3 environments
 *
 * Revision 1.7  1996/05/24  22:17:04  jimz
 * continue code + namespace cleanup
 * typed a bunch of flags
 *
 * Revision 1.6  1996/05/24  04:28:55  jimz
 * release cleanup ckpt
 *
 * Revision 1.5  1996/05/23  21:46:35  jimz
 * checkpoint in code cleanup (release prep)
 * lots of types, function names have been fixed
 *
 * Revision 1.4  1996/05/23  00:33:23  jimz
 * code cleanup: move all debug decls to rf_options.c, all extern
 * debug decls to rf_options.h, all debug vars preceded by rf_
 *
 * Revision 1.3  1996/05/18  19:51:34  jimz
 * major code cleanup- fix syntax, make some types consistent,
 * add prototypes, clean out dead code, et cetera
 *
 * Revision 1.2  1996/05/08  21:01:24  jimz
 * fixed up enum type names that were conflicting with other
 * enums and function names (ie, "panic")
 * future naming trends will be towards RF_ and rf_ for
 * everything raidframe-related
 *
 * Revision 1.1  1996/05/03  19:19:20  wvcii
 * Initial revision
 *
 */

#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)(), (*undoFunc)();
  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),