FreeBSD/Linux Kernel Cross Reference
sys/dev/raidframe/rf_pqdeg.c

     /*      $NetBSD: rf_pqdeg.c,v 1.7 2001/11/13 07:11:16 lukem Exp $       */
     /*
      * Copyright (c) 1995 Carnegie-Mellon University.
      * All rights reserved.
      *
      * Author: Daniel Stodolsky
      *
      * 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.
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: rf_pqdeg.c,v 1.7 2001/11/13 07:11:16 lukem Exp $");
    
    #include "rf_archs.h"
    
    #if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
    
    #include <dev/raidframe/raidframevar.h>
    
    #include "rf_raid.h"
    #include "rf_dag.h"
    #include "rf_dagutils.h"
    #include "rf_dagfuncs.h"
    #include "rf_dagffrd.h"
    #include "rf_dagffwr.h"
    #include "rf_dagdegrd.h"
    #include "rf_dagdegwr.h"
    #include "rf_etimer.h"
    #include "rf_pqdeg.h"
    #include "rf_general.h"
    #include "rf_pqdegdags.h"
    #include "rf_pq.h"
    
    /*
       Degraded mode dag functions for P+Q calculations.
    
       The following nomenclature is used.
    
       PQ_<D><P><Q>_Create{Large,Small}<Write|Read>DAG
    
       where <D><P><Q> are single digits representing the number of failed
       data units <D> (0,1,2), parity units <P> (0,1), and Q units <Q>, effecting
       the I/O. The reads have only  PQ_<D><P><Q>_CreateReadDAG variants, while
       the single fault writes have both large and small write versions. (Single fault
       PQ is equivalent to normal mode raid 5 in many aspects.
    
       Some versions degenerate into the same case, and are grouped together below.
    */
    
    /* Reads, single failure
    
       we have parity, so we can do a raid 5
       reconstruct read.
    */
    
    RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateReadDAG)
    {
            rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList, &rf_pRecoveryFuncs);
    }
    /* Reads double failure  */
    
    /*
       Q is lost, but not parity
       so we can a raid 5 reconstruct read.
    */
    
    RF_CREATE_DAG_FUNC_DECL(rf_PQ_101_CreateReadDAG)
    {
            rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList, &rf_pRecoveryFuncs);
    }
    /*
      parity is lost, so we need to
      do a reconstruct read and recompute
      the data with Q.
    */
    
    RF_CREATE_DAG_FUNC_DECL(rf_PQ_110_CreateReadDAG)
    {
            RF_PhysDiskAddr_t *temp;
            /* swap P and Q pointers to fake out the DegradedReadDAG code */
            temp = asmap->parityInfo;
           asmap->parityInfo = asmap->qInfo;
           asmap->qInfo = temp;
           rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList, &rf_qRecoveryFuncs);
   }
   /*
     Two data units are dead in this stripe, so we will need read
     both P and Q to reconstruct the data. Note that only
     one data unit we are reading may actually be missing.
   */
   RF_CREATE_DAG_FUNC_DECL(rf_CreateDoubleDegradedReadDAG);
   RF_CREATE_DAG_FUNC_DECL(rf_CreateDoubleDegradedReadDAG)
   {
           rf_PQ_DoubleDegRead(raidPtr, asmap, dag_h, bp, flags, allocList);
   }
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_200_CreateReadDAG);
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_200_CreateReadDAG)
   {
           rf_CreateDoubleDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList);
   }
   /* Writes, single failure */
   
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateWriteDAG);
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateWriteDAG)
   {
           if (asmap->numStripeUnitsAccessed != 1 &&
               asmap->failedPDAs[0]->numSector != 
               raidPtr->Layout.sectorsPerStripeUnit)
                   RF_PANIC();
           rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp, 
                         flags, allocList, 2, 
                         (int (*) (RF_DagNode_t *)) rf_Degraded_100_PQFunc, 
                         RF_FALSE);
   }
   /* Dead  P - act like a RAID 5 small write with parity = Q */
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_010_CreateSmallWriteDAG)
   {
           RF_PhysDiskAddr_t *temp;
           /* swap P and Q pointers to fake out the DegradedReadDAG code */
           temp = asmap->parityInfo;
           asmap->parityInfo = asmap->qInfo;
           asmap->qInfo = temp;
           rf_CommonCreateSmallWriteDAG(raidPtr, asmap, dag_h, bp, flags, 
                                        allocList, &rf_qFuncs, NULL);
   }
   /* Dead Q - act like a RAID 5 small write */
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_001_CreateSmallWriteDAG)
   {
           rf_CommonCreateSmallWriteDAG(raidPtr, asmap, dag_h, bp, flags, 
                                        allocList, &rf_pFuncs, NULL);
   }
   /* Dead P - act like a RAID 5 large write but for Q */
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_010_CreateLargeWriteDAG)
   {
           RF_PhysDiskAddr_t *temp;
           /* swap P and Q pointers to fake out the code */
           temp = asmap->parityInfo;
           asmap->parityInfo = asmap->qInfo;
           asmap->qInfo = temp;
           rf_CommonCreateLargeWriteDAG(raidPtr, asmap, dag_h, bp, flags, 
                                        allocList, 1, rf_RegularQFunc, RF_FALSE);
   }
   /* Dead Q - act like a RAID 5 large write */
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_001_CreateLargeWriteDAG)
   {
           rf_CommonCreateLargeWriteDAG(raidPtr, asmap, dag_h, bp, flags, 
                                        allocList, 1, rf_RegularPFunc, RF_FALSE);
   }
   
   
   /*
    * writes, double failure
    */
   
   /*
    * Lost P & Q - do a nonredundant write
    */
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_011_CreateWriteDAG)
   {
           rf_CreateNonRedundantWriteDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
               RF_IO_TYPE_WRITE);
   }
   /*
      In the two cases below,
      A nasty case arises when the write a (strict) portion of a failed stripe unit
      and parts of another su. For now, we do not support this.
   */
   
   /*
     Lost Data and  P - do a Q write.
   */
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_110_CreateWriteDAG)
   {
           RF_PhysDiskAddr_t *temp;
   
           if (asmap->numStripeUnitsAccessed != 1 &&
               asmap->failedPDAs[0]->numSector != raidPtr->Layout.sectorsPerStripeUnit) {
                   RF_PANIC();
           }
           /* swap P and Q to fake out parity code */
           temp = asmap->parityInfo;
           asmap->parityInfo = asmap->qInfo;
           asmap->qInfo = temp;
           rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp, flags,
                         allocList, 1, 
                         (int (*) (RF_DagNode_t *)) rf_PQ_DegradedWriteQFunc,
                         RF_FALSE);
           /* is the regular Q func the right one to call? */
   }
   /*
      Lost Data and Q - do degraded mode P write
   */
   RF_CREATE_DAG_FUNC_DECL(rf_PQ_101_CreateWriteDAG)
   {
           if (asmap->numStripeUnitsAccessed != 1 &&
               asmap->failedPDAs[0]->numSector != raidPtr->Layout.sectorsPerStripeUnit)
                   RF_PANIC();
           rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp, flags,
               allocList, 1, rf_RecoveryXorFunc, RF_FALSE);
   }
   #endif                          /* (RF_INCLUDE_DECL_PQ > 0) ||
                                    * (RF_INCLUDE_RAID6 > 0) */

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