NetBSD/sys/dev/raidframe/rf_map.c

/*	$NetBSD: rf_map.c,v 1.2 1999/01/26 02:33:58 oster Exp $	*/
/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: Mark Holland
 *
 * 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.
 */

/**************************************************************************
 *
 * map.c -- main code for mapping RAID addresses to physical disk addresses
 *
 **************************************************************************/

#include "rf_types.h"
#include "rf_threadstuff.h"
#include "rf_raid.h"
#include "rf_general.h"
#include "rf_map.h"
#include "rf_freelist.h"
#include "rf_shutdown.h"
#include "rf_sys.h"

static void rf_FreePDAList(RF_PhysDiskAddr_t *start, RF_PhysDiskAddr_t *end, int count);
static void rf_FreeASMList(RF_AccessStripeMap_t *start, RF_AccessStripeMap_t *end,
	int count);

/*****************************************************************************************
 *
 * MapAccess -- main 1st order mapping routine.
 *
 * Maps an access in the RAID address space to the corresponding set of physical disk
 * addresses.  The result is returned as a list of AccessStripeMap structures, one per
 * stripe accessed.  Each ASM structure contains a pointer to a list of PhysDiskAddr
 * structures, which describe the physical locations touched by the user access.  Note
 * that this routine returns only static mapping information, i.e. the list of physical
 * addresses returned does not necessarily identify the set of physical locations that
 * will actually be read or written.
 *
 * The routine also maps the parity.  The physical disk location returned always
 * indicates the entire parity unit, even when only a subset of it is being accessed.
 * This is because an access that is not stripe unit aligned but that spans a stripe
 * unit boundary may require access two distinct portions of the parity unit, and we
 * can't yet tell which portion(s) we'll actually need.  We leave it up to the algorithm
 * selection code to decide what subset of the parity unit to access.
 *
 * Note that addresses in the RAID address space must always be maintained as
 * longs, instead of ints.
 *
 * This routine returns NULL if numBlocks is 0
 *
 ****************************************************************************************/

RF_AccessStripeMapHeader_t *rf_MapAccess(raidPtr, raidAddress, numBlocks, buffer, remap)
  RF_Raid_t         *raidPtr;
  RF_RaidAddr_t      raidAddress; /* starting address in RAID address space */
  RF_SectorCount_t   numBlocks;   /* number of blocks in RAID address space to access */
  caddr_t            buffer;      /* buffer to supply/receive data */
  int                remap;       /* 1 => remap addresses to spare space */
{
  RF_RaidLayout_t            *layoutPtr       = &(raidPtr->Layout);
  RF_AccessStripeMapHeader_t *asm_hdr         = NULL;
  RF_AccessStripeMap_t       *asm_list        = NULL, *asm_p = NULL;
  int                         faultsTolerated = layoutPtr->map->faultsTolerated;
  RF_RaidAddr_t               startAddress    = raidAddress;            /* we'll change raidAddress along the way */
  RF_RaidAddr_t               endAddress      = raidAddress + numBlocks;
  RF_RaidDisk_t             **disks           = raidPtr->Disks;

  RF_PhysDiskAddr_t          *pda_p, *pda_q;
  RF_StripeCount_t            numStripes = 0;
  RF_RaidAddr_t               stripeRealEndAddress, stripeEndAddress, nextStripeUnitAddress;
  RF_RaidAddr_t               startAddrWithinStripe, lastRaidAddr;
  RF_StripeCount_t            totStripes;
  RF_StripeNum_t              stripeID, lastSID, SUID, lastSUID;
  RF_AccessStripeMap_t  *asmList, *t_asm;
  RF_PhysDiskAddr_t     *pdaList, *t_pda;

  /* allocate all the ASMs and PDAs up front */
  lastRaidAddr = raidAddress + numBlocks - 1 ;
  stripeID     = rf_RaidAddressToStripeID(layoutPtr, raidAddress);
  lastSID      = rf_RaidAddressToStripeID(layoutPtr, lastRaidAddr);
  totStripes   = lastSID - stripeID + 1;
  SUID         = rf_RaidAddressToStripeUnitID(layoutPtr, raidAddress);
  lastSUID     = rf_RaidAddressToStripeUnitID(layoutPtr, lastRaidAddr);

  asmList = rf_AllocASMList(totStripes);
  pdaList = rf_AllocPDAList(lastSUID - SUID + 1 + faultsTolerated * totStripes);     /* may also need pda(s) per stripe for parity */
  
  if (raidAddress+numBlocks > raidPtr->totalSectors) {
    RF_ERRORMSG1("Unable to map access because offset (%d) was invalid\n", 
		 (int)raidAddress);
    return(NULL);
  }

  if (rf_mapDebug)
    rf_PrintRaidAddressInfo(raidPtr, raidAddress, numBlocks);
  for (; raidAddress < endAddress; ) {
    /* make the next stripe structure */
    RF_ASSERT(asmList);
    t_asm = asmList;
    asmList = asmList->next;
    bzero((char *)t_asm, sizeof(RF_AccessStripeMap_t));
    if (!asm_p)
      asm_list = asm_p = t_asm;
    else {
      asm_p->next = t_asm;
      asm_p = asm_p->next;
    }
    numStripes++;

    /* map SUs from current location to the end of the stripe */
    asm_p->stripeID = /*rf_RaidAddressToStripeID(layoutPtr, raidAddress)*/ stripeID++;
    stripeRealEndAddress = rf_RaidAddressOfNextStripeBoundary(layoutPtr, raidAddress);
    stripeEndAddress = RF_MIN(endAddress,stripeRealEndAddress );
    asm_p->raidAddress    = raidAddress;
    asm_p->endRaidAddress = stripeEndAddress;

    /* map each stripe unit in the stripe */
    pda_p = NULL;
    startAddrWithinStripe = raidAddress;      /* Raid addr of start of portion of access that is within this stripe */
    for (; raidAddress < stripeEndAddress; ) {
      RF_ASSERT(pdaList);
      t_pda = pdaList;
      pdaList = pdaList->next;
      bzero((char *)t_pda, sizeof(RF_PhysDiskAddr_t));
      if (!pda_p) 
	asm_p->physInfo = pda_p = t_pda;
      else {
        pda_p->next = t_pda;
        pda_p = pda_p->next;
      }
      
      pda_p->type = RF_PDA_TYPE_DATA;
      (layoutPtr->map->MapSector)(raidPtr, raidAddress, &(pda_p->row), &(pda_p->col), &(pda_p->startSector), remap);

      /* mark any failures we find.  failedPDA is don't-care if there is more than one failure */
      pda_p->raidAddress = raidAddress;          /* the RAID address corresponding to this physical disk address */
      nextStripeUnitAddress = rf_RaidAddressOfNextStripeUnitBoundary(layoutPtr, raidAddress);
      pda_p->numSector = RF_MIN(endAddress, nextStripeUnitAddress) - raidAddress;
      RF_ASSERT(pda_p->numSector != 0);
      rf_ASMCheckStatus(raidPtr,pda_p,asm_p,disks,0);
      pda_p->bufPtr = buffer + rf_RaidAddressToByte(raidPtr, (raidAddress - startAddress));
      asm_p->totalSectorsAccessed += pda_p->numSector;
      asm_p->numStripeUnitsAccessed++;
      asm_p->origRow = pda_p->row;               /* redundant but harmless to do this in every loop iteration */
      
      raidAddress = RF_MIN(endAddress, nextStripeUnitAddress);
    }

    /* Map the parity. At this stage, the startSector and numSector fields
     * for the parity unit are always set to indicate the entire parity unit.
     * We may modify this after mapping the data portion.
     */
    switch (faultsTolerated)
      {
      case 0:
	break;
      case 1: /* single fault tolerant */
	RF_ASSERT(pdaList);
	t_pda = pdaList;
	pdaList = pdaList->next;
	bzero((char *)t_pda, sizeof(RF_PhysDiskAddr_t));
	pda_p = asm_p->parityInfo = t_pda;
	pda_p->type = RF_PDA_TYPE_PARITY;
	(layoutPtr->map->MapParity)(raidPtr, rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe),
				    &(pda_p->row), &(pda_p->col), &(pda_p->startSector), remap);
	pda_p->numSector = layoutPtr->sectorsPerStripeUnit;
	/* raidAddr may be needed to find unit to redirect to */
	pda_p->raidAddress = rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe);
	rf_ASMCheckStatus(raidPtr,pda_p,asm_p,disks,1);
	rf_ASMParityAdjust(asm_p->parityInfo,startAddrWithinStripe,endAddress,layoutPtr,asm_p);

	break;
      case 2: /* two fault tolerant */
	RF_ASSERT(pdaList && pdaList->next);
	t_pda = pdaList;
	pdaList = pdaList->next;
	bzero((char *)t_pda, sizeof(RF_PhysDiskAddr_t));
	pda_p = asm_p->parityInfo = t_pda;
	pda_p->type = RF_PDA_TYPE_PARITY;
	t_pda = pdaList;
	pdaList = pdaList->next;
	bzero((char *)t_pda, sizeof(RF_PhysDiskAddr_t));
	pda_q = asm_p->qInfo = t_pda;
	pda_q->type = RF_PDA_TYPE_Q;
	(layoutPtr->map->MapParity)(raidPtr, rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe),
				    &(pda_p->row), &(pda_p->col), &(pda_p->startSector), remap);
	(layoutPtr->map->MapQ)(raidPtr, rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe),
			       &(pda_q->row), &(pda_q->col), &(pda_q->startSector), remap);
	pda_q->numSector = pda_p->numSector = layoutPtr->sectorsPerStripeUnit;
	/* raidAddr may be needed to find unit to redirect to */
	pda_p->raidAddress = rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe);
	pda_q->raidAddress = rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe);
	/* failure mode stuff */
	rf_ASMCheckStatus(raidPtr,pda_p,asm_p,disks,1);
	rf_ASMCheckStatus(raidPtr,pda_q,asm_p,disks,1);
	rf_ASMParityAdjust(asm_p->parityInfo,startAddrWithinStripe,endAddress,layoutPtr,asm_p);
	rf_ASMParityAdjust(asm_p->qInfo,startAddrWithinStripe,endAddress,layoutPtr,asm_p);
	break;
      }
  }
  RF_ASSERT(asmList == NULL && pdaList == NULL);
  /* make the header structure */
  asm_hdr = rf_AllocAccessStripeMapHeader();
  RF_ASSERT(numStripes == totStripes);
  asm_hdr->numStripes = numStripes;
  asm_hdr->stripeMap  = asm_list;

  if (rf_mapDebug)
    rf_PrintAccessStripeMap(asm_hdr);
  return(asm_hdr);
}

/*****************************************************************************************
 * This routine walks through an ASM list and marks the PDAs that have failed.
 * It's called only when a disk failure causes an in-flight DAG to fail.
 * The parity may consist of two components, but we want to use only one failedPDA
 * pointer.  Thus we set failedPDA to point to the first parity component, and rely
 * on the rest of the code to do the right thing with this.
 ****************************************************************************************/

void rf_MarkFailuresInASMList(raidPtr, asm_h)
  RF_Raid_t                   *raidPtr;
  RF_AccessStripeMapHeader_t  *asm_h;
{
  RF_RaidDisk_t  **disks = raidPtr->Disks;
  RF_AccessStripeMap_t *asmap;
  RF_PhysDiskAddr_t *pda;
  
  for (asmap = asm_h->stripeMap; asmap; asmap = asmap->next) {
    asmap->numDataFailed = asmap->numParityFailed = asmap->numQFailed = 0;
    asmap->numFailedPDAs = 0;
    bzero((char *)asmap->failedPDAs,
      RF_MAX_FAILED_PDA*sizeof(RF_PhysDiskAddr_t *));
    for (pda = asmap->physInfo; pda; pda=pda->next) {
      if (RF_DEAD_DISK(disks[pda->row][pda->col].status)) {
	      printf("DEAD DISK BOGUSLY DETECTED!!\n");
        asmap->numDataFailed++;
        asmap->failedPDAs[asmap->numFailedPDAs] = pda;
        asmap->numFailedPDAs++;
      }
    }
    pda = asmap->parityInfo;
    if (pda && RF_DEAD_DISK(disks[pda->row][pda->col].status)) {
      asmap->numParityFailed++;
      asmap->failedPDAs[asmap->numFailedPDAs] = pda;
      asmap->numFailedPDAs++;
    }
    pda = asmap->qInfo;
    if (pda && RF_DEAD_DISK(disks[pda->row][pda->col].status)) {
      asmap->numQFailed++;
      asmap->failedPDAs[asmap->numFailedPDAs] = pda;
      asmap->numFailedPDAs++;
    }
  }
}

/*****************************************************************************************
 *
 * DuplicateASM -- duplicates an ASM and returns the new one
 *
 ****************************************************************************************/
RF_AccessStripeMap_t *rf_DuplicateASM(asmap)
  RF_AccessStripeMap_t  *asmap;
{
  RF_AccessStripeMap_t *new_asm;
  RF_PhysDiskAddr_t *pda, *new_pda, *t_pda;

  new_pda = NULL;
  new_asm = rf_AllocAccessStripeMapComponent();
  bcopy((char *)asmap, (char *)new_asm, sizeof(RF_AccessStripeMap_t));
  new_asm->numFailedPDAs = 0; /* ??? */
  new_asm->failedPDAs[0] = NULL;
  new_asm->physInfo = NULL;
  new_asm->parityInfo = NULL;
  new_asm->next = NULL;

  for (pda = asmap->physInfo; pda; pda=pda->next) {      /* copy the physInfo list */
    t_pda = rf_AllocPhysDiskAddr();
    bcopy((char *)pda, (char *)t_pda, sizeof(RF_PhysDiskAddr_t));
    t_pda->next = NULL;
    if (!new_asm->physInfo) {new_asm->physInfo = t_pda; new_pda = t_pda;}
    else {new_pda->next = t_pda; new_pda = new_pda->next;}
    if (pda == asmap->failedPDAs[0])
      new_asm->failedPDAs[0] = t_pda;
  }
  for (pda = asmap->parityInfo; pda; pda=pda->next) {      /* copy the parityInfo list */
    t_pda = rf_AllocPhysDiskAddr();
    bcopy((char *)pda, (char *)t_pda, sizeof(RF_PhysDiskAddr_t));
    t_pda->next = NULL;
    if (!new_asm->parityInfo) {new_asm->parityInfo = t_pda; new_pda = t_pda;}
    else {new_pda->next = t_pda; new_pda = new_pda->next;}
    if (pda == asmap->failedPDAs[0])
      new_asm->failedPDAs[0] = t_pda;
  }
  return(new_asm);
}

/*****************************************************************************************
 *
 * DuplicatePDA -- duplicates a PDA and returns the new one
 *
 ****************************************************************************************/
RF_PhysDiskAddr_t *rf_DuplicatePDA(pda)
  RF_PhysDiskAddr_t  *pda;
{
  RF_PhysDiskAddr_t *new;

  new = rf_AllocPhysDiskAddr();
  bcopy((char *)pda, (char *)new, sizeof(RF_PhysDiskAddr_t));
  return(new);
}

/*****************************************************************************************
 *
 * routines to allocate and free list elements.  All allocation routines zero the
 * structure before returning it.
 *
 * FreePhysDiskAddr is static.  It should never be called directly, because
 * FreeAccessStripeMap takes care of freeing the PhysDiskAddr list.
 *
 ****************************************************************************************/

static RF_FreeList_t *rf_asmhdr_freelist;
#define RF_MAX_FREE_ASMHDR 128
#define RF_ASMHDR_INC       16
#define RF_ASMHDR_INITIAL   32

static RF_FreeList_t *rf_asm_freelist;
#define RF_MAX_FREE_ASM 192
#define RF_ASM_INC       24
#define RF_ASM_INITIAL   64

static RF_FreeList_t *rf_pda_freelist;
#define RF_MAX_FREE_PDA 192
#define RF_PDA_INC       24
#define RF_PDA_INITIAL   64

/* called at shutdown time.  So far, all that is necessary is to release all the free lists */
static void rf_ShutdownMapModule(void *);
static void rf_ShutdownMapModule(ignored)
  void  *ignored;
{
  RF_FREELIST_DESTROY(rf_asmhdr_freelist,next,(RF_AccessStripeMapHeader_t *));
  RF_FREELIST_DESTROY(rf_pda_freelist,next,(RF_PhysDiskAddr_t *));
  RF_FREELIST_DESTROY(rf_asm_freelist,next,(RF_AccessStripeMap_t *));
}

int rf_ConfigureMapModule(listp)
  RF_ShutdownList_t  **listp;
{
	int rc;

	RF_FREELIST_CREATE(rf_asmhdr_freelist, RF_MAX_FREE_ASMHDR,
		RF_ASMHDR_INC, sizeof(RF_AccessStripeMapHeader_t));
	if (rf_asmhdr_freelist == NULL) {
		return(ENOMEM);
	}
	RF_FREELIST_CREATE(rf_asm_freelist, RF_MAX_FREE_ASM,
		RF_ASM_INC, sizeof(RF_AccessStripeMap_t));
	if (rf_asm_freelist == NULL) {
		RF_FREELIST_DESTROY(rf_asmhdr_freelist,next,(RF_AccessStripeMapHeader_t *));
		return(ENOMEM);
	}
	RF_FREELIST_CREATE(rf_pda_freelist, RF_MAX_FREE_PDA,
		RF_PDA_INC, sizeof(RF_PhysDiskAddr_t));
	if (rf_pda_freelist == NULL) {
		RF_FREELIST_DESTROY(rf_asmhdr_freelist,next,(RF_AccessStripeMapHeader_t *));
		RF_FREELIST_DESTROY(rf_pda_freelist,next,(RF_PhysDiskAddr_t *));
		return(ENOMEM);
	}

	rc = rf_ShutdownCreate(listp, rf_ShutdownMapModule, NULL);
	if (rc) {
		RF_ERRORMSG3("Unable to add to shutdown list file %s line %d rc=%d\n", __FILE__,
			__LINE__, rc);
		rf_ShutdownMapModule(NULL);
		return(rc);
	}

	RF_FREELIST_PRIME(rf_asmhdr_freelist, RF_ASMHDR_INITIAL,next,
		(RF_AccessStripeMapHeader_t *));
	RF_FREELIST_PRIME(rf_asm_freelist, RF_ASM_INITIAL,next,
		(RF_AccessStripeMap_t *));
	RF_FREELIST_PRIME(rf_pda_freelist, RF_PDA_INITIAL,next,
		(RF_PhysDiskAddr_t *));

	return(0);
}

RF_AccessStripeMapHeader_t *rf_AllocAccessStripeMapHeader()
{
	RF_AccessStripeMapHeader_t *p;

	RF_FREELIST_GET(rf_asmhdr_freelist,p,next,(RF_AccessStripeMapHeader_t *));
	bzero((char *)p, sizeof(RF_AccessStripeMapHeader_t));

	return(p);
}


void rf_FreeAccessStripeMapHeader(p)
  RF_AccessStripeMapHeader_t  *p;
{
	RF_FREELIST_FREE(rf_asmhdr_freelist,p,next);
}

RF_PhysDiskAddr_t *rf_AllocPhysDiskAddr()
{
	RF_PhysDiskAddr_t *p;

	RF_FREELIST_GET(rf_pda_freelist,p,next,(RF_PhysDiskAddr_t *));
	bzero((char *)p, sizeof(RF_PhysDiskAddr_t));

	return(p);
}

/* allocates a list of PDAs, locking the free list only once
 * when we have to call calloc, we do it one component at a time to simplify
 * the process of freeing the list at program shutdown.  This should not be
 * much of a performance hit, because it should be very infrequently executed.
 */
RF_PhysDiskAddr_t *rf_AllocPDAList(count)
  int  count;
{
	RF_PhysDiskAddr_t *p = NULL;

	RF_FREELIST_GET_N(rf_pda_freelist,p,next,(RF_PhysDiskAddr_t *),count);
	return(p);
}

void rf_FreePhysDiskAddr(p)
  RF_PhysDiskAddr_t  *p;
{
	RF_FREELIST_FREE(rf_pda_freelist,p,next);
}

static void rf_FreePDAList(l_start, l_end, count)
  RF_PhysDiskAddr_t *l_start, *l_end;   /* pointers to start and end of list */
  int count;                            /* number of elements in list */
{
	RF_FREELIST_FREE_N(rf_pda_freelist,l_start,next,(RF_PhysDiskAddr_t *),count);
}

RF_AccessStripeMap_t *rf_AllocAccessStripeMapComponent()
{
	RF_AccessStripeMap_t *p;

	RF_FREELIST_GET(rf_asm_freelist,p,next,(RF_AccessStripeMap_t *));
	bzero((char *)p, sizeof(RF_AccessStripeMap_t));

	return(p);
}

/* this is essentially identical to AllocPDAList.  I should combine the two.
 * when we have to call calloc, we do it one component at a time to simplify
 * the process of freeing the list at program shutdown.  This should not be
 * much of a performance hit, because it should be very infrequently executed.
 */
RF_AccessStripeMap_t *rf_AllocASMList(count)
  int  count;
{
	RF_AccessStripeMap_t *p = NULL;

	RF_FREELIST_GET_N(rf_asm_freelist,p,next,(RF_AccessStripeMap_t *),count);
	return(p);
}

void rf_FreeAccessStripeMapComponent(p)
  RF_AccessStripeMap_t  *p;
{
	RF_FREELIST_FREE(rf_asm_freelist,p,next);
}

static void rf_FreeASMList(l_start, l_end, count)
  RF_AccessStripeMap_t  *l_start, *l_end;
  int                    count;
{
	RF_FREELIST_FREE_N(rf_asm_freelist,l_start,next,(RF_AccessStripeMap_t *),count);
}

void rf_FreeAccessStripeMap(hdr)
  RF_AccessStripeMapHeader_t  *hdr;
{
  RF_AccessStripeMap_t *p, *pt = NULL;
  RF_PhysDiskAddr_t *pdp, *trailer, *pdaList = NULL, *pdaEnd = NULL;
  int count = 0, t, asm_count = 0;

  for (p = hdr->stripeMap; p; p=p->next) {
    
    /* link the 3 pda lists into the accumulating pda list */
    
    if (!pdaList) pdaList = p->qInfo; else pdaEnd->next = p->qInfo;
    for (trailer=NULL,pdp=p->qInfo; pdp; ) {trailer = pdp; pdp=pdp->next; count++;}
    if (trailer) pdaEnd = trailer;
    
    if (!pdaList) pdaList = p->parityInfo; else pdaEnd->next = p->parityInfo;
    for (trailer=NULL,pdp=p->parityInfo; pdp; ) {trailer = pdp; pdp=pdp->next; count++;}
    if (trailer) pdaEnd = trailer;

    if (!pdaList) pdaList = p->physInfo; else pdaEnd->next = p->physInfo;
    for (trailer=NULL,pdp=p->physInfo; pdp; ) {trailer = pdp; pdp=pdp->next; count++;}
    if (trailer) pdaEnd = trailer;

    pt = p;
    asm_count++;
  }
  
  /* debug only */
  for (t=0,pdp=pdaList; pdp; pdp=pdp->next)
    t++;
  RF_ASSERT(t == count);

  if (pdaList)
    rf_FreePDAList(pdaList, pdaEnd, count);
  rf_FreeASMList(hdr->stripeMap, pt, asm_count);
  rf_FreeAccessStripeMapHeader(hdr);
}

/* We can't use the large write optimization if there are any failures in the stripe.
 * In the declustered layout, there is no way to immediately determine what disks
 * constitute a stripe, so we actually have to hunt through the stripe looking for failures.
 * The reason we map the parity instead of just using asm->parityInfo->col is because
 * the latter may have been already redirected to a spare drive, which would
 * mess up the computation of the stripe offset.
 *
 * ASSUMES AT MOST ONE FAILURE IN THE STRIPE.
 */
int rf_CheckStripeForFailures(raidPtr, asmap)
  RF_Raid_t             *raidPtr;
  RF_AccessStripeMap_t  *asmap;
{
  RF_RowCol_t trow, tcol, prow, pcol, *diskids, row, i;
  RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
  RF_StripeCount_t stripeOffset;
  int numFailures;
  RF_RaidAddr_t sosAddr;
  RF_SectorNum_t diskOffset, poffset;
  RF_RowCol_t testrow;

  /* quick out in the fault-free case.  */
  RF_LOCK_MUTEX(raidPtr->mutex);
  numFailures = raidPtr->numFailures;
  RF_UNLOCK_MUTEX(raidPtr->mutex);
  if (numFailures == 0) return(0);

  sosAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr, asmap->raidAddress);
  row = asmap->physInfo->row;
  (layoutPtr->map->IdentifyStripe)(raidPtr, asmap->raidAddress, &diskids, &testrow);
  (layoutPtr->map->MapParity)(raidPtr, asmap->raidAddress, &prow, &pcol, &poffset, 0);  /* get pcol */
  
  /* this need not be true if we've redirected the access to a spare in another row 
  RF_ASSERT(row == testrow);
  */
  stripeOffset = 0;
  for (i=0; i<layoutPtr->numDataCol+layoutPtr->numParityCol; i++) {
    if (diskids[i] != pcol) {
      if (RF_DEAD_DISK(raidPtr->Disks[testrow][diskids[i]].status)) {
        if (raidPtr->status[testrow] != rf_rs_reconstructing)
          return(1);
        RF_ASSERT(raidPtr->reconControl[testrow]->fcol == diskids[i]);
        layoutPtr->map->MapSector(raidPtr,
          sosAddr + stripeOffset * layoutPtr->sectorsPerStripeUnit,
          &trow, &tcol, &diskOffset, 0);
        RF_ASSERT( (trow == testrow) && (tcol == diskids[i]) );
        if (!rf_CheckRUReconstructed(raidPtr->reconControl[testrow]->reconMap, diskOffset))
          return(1);
        asmap->flags |= RF_ASM_REDIR_LARGE_WRITE;
        return(0);
      }
      stripeOffset++;
    }
  }
  return(0);
}

/*
   return the number of failed data units in the stripe.
*/

int rf_NumFailedDataUnitsInStripe(raidPtr, asmap)
  RF_Raid_t             *raidPtr;
  RF_AccessStripeMap_t  *asmap;
{
  RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
  RF_RowCol_t trow, tcol, row, i;
  RF_SectorNum_t diskOffset;
  RF_RaidAddr_t sosAddr;
  int numFailures;

  /* quick out in the fault-free case.  */
  RF_LOCK_MUTEX(raidPtr->mutex);
  numFailures = raidPtr->numFailures;
  RF_UNLOCK_MUTEX(raidPtr->mutex);
  if (numFailures == 0) return(0);
  numFailures = 0;

  sosAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr, asmap->raidAddress);
  row = asmap->physInfo->row;
  for (i=0; i<layoutPtr->numDataCol; i++) 
    {
      (layoutPtr->map->MapSector)(raidPtr, sosAddr + i * layoutPtr->sectorsPerStripeUnit, 
				  &trow, &tcol, &diskOffset, 0);
      if (RF_DEAD_DISK(raidPtr->Disks[trow][tcol].status)) 
	numFailures++;
    }

  return numFailures;
}


/*****************************************************************************************
 *
 * debug routines
 *
 ****************************************************************************************/

void rf_PrintAccessStripeMap(asm_h)
  RF_AccessStripeMapHeader_t  *asm_h;
{
  rf_PrintFullAccessStripeMap(asm_h, 0);
}

void rf_PrintFullAccessStripeMap(asm_h, prbuf)
  RF_AccessStripeMapHeader_t  *asm_h;
  int                          prbuf; /* flag to print buffer pointers */
{
  int i;
  RF_AccessStripeMap_t *asmap = asm_h->stripeMap;
  RF_PhysDiskAddr_t *p;
  printf("%d stripes total\n", (int)asm_h->numStripes);
  for (; asmap; asmap = asmap->next) {
	  /* 	  printf("Num failures: %d\n",asmap->numDataFailed); */
	  /* printf("Num sectors: %d\n",(int)asmap->totalSectorsAccessed); */
    printf("Stripe %d (%d sectors), failures: %d data, %d parity: ",
	   (int) asmap->stripeID,
	   (int) asmap->totalSectorsAccessed,
	   (int) asmap->numDataFailed,
	   (int) asmap->numParityFailed);
    if (asmap->parityInfo) {
      printf("Parity [r%d c%d s%d-%d", asmap->parityInfo->row, asmap->parityInfo->col,
	     (int)asmap->parityInfo->startSector, 
	     (int)(asmap->parityInfo->startSector +
		   asmap->parityInfo->numSector - 1));
      if (prbuf) printf(" b0x%lx",(unsigned long) asmap->parityInfo->bufPtr);
      if (asmap->parityInfo->next) {
	printf(", r%d c%d s%d-%d", asmap->parityInfo->next->row, 
	       asmap->parityInfo->next->col,
	       (int) asmap->parityInfo->next->startSector, 
	       (int)(asmap->parityInfo->next->startSector + 
		     asmap->parityInfo->next->numSector - 1));
	if (prbuf) printf(" b0x%lx",(unsigned long) asmap->parityInfo->next->bufPtr);
	RF_ASSERT(asmap->parityInfo->next->next == NULL);
      }
      printf("]\n\t");
    }
    for (i=0,p=asmap->physInfo; p; p=p->next,i++) {
      printf("SU r%d c%d s%d-%d ", p->row, p->col, (int)p->startSector, 
	     (int)(p->startSector + p->numSector - 1));
      if (prbuf) printf("b0x%lx ", (unsigned long) p->bufPtr);
      if (i && !(i&1)) printf("\n\t");
    }
    printf("\n");
    p = asm_h->stripeMap->failedPDAs[0];
    if (asm_h->stripeMap->numDataFailed + asm_h->stripeMap->numParityFailed > 1) printf("[multiple failures]\n");
    else if (asm_h->stripeMap->numDataFailed + asm_h->stripeMap->numParityFailed > 0)
      printf("\t[Failed PDA: r%d c%d s%d-%d]\n",p->row, p->col, 
	     (int)p->startSector, (int)(p->startSector + p->numSector-1));
  }
}

void rf_PrintRaidAddressInfo(raidPtr, raidAddr, numBlocks)
  RF_Raid_t         *raidPtr;
  RF_RaidAddr_t      raidAddr;
  RF_SectorCount_t   numBlocks;
{
  RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
  RF_RaidAddr_t ra, sosAddr  = rf_RaidAddressOfPrevStripeBoundary(layoutPtr, raidAddr);

  printf("Raid addrs of SU boundaries from start of stripe to end of access:\n\t");
  for (ra = sosAddr; ra <= raidAddr + numBlocks; ra += layoutPtr->sectorsPerStripeUnit) {
    printf("%d (0x%x), ",(int)ra, (int)ra);
  }
  printf("\n");
  printf("Offset into stripe unit: %d (0x%x)\n",
	 (int)(raidAddr % layoutPtr->sectorsPerStripeUnit),
	 (int)(raidAddr % layoutPtr->sectorsPerStripeUnit));
}

/*
   given a parity descriptor and the starting address within a stripe,
   range restrict the parity descriptor to touch only the correct stuff.
*/
void rf_ASMParityAdjust(
  RF_PhysDiskAddr_t     *toAdjust, 
  RF_StripeNum_t         startAddrWithinStripe, 
  RF_SectorNum_t         endAddress, 
  RF_RaidLayout_t       *layoutPtr, 
  RF_AccessStripeMap_t  *asm_p)
{
  RF_PhysDiskAddr_t *new_pda;

  /* when we're accessing only a portion of one stripe unit, we want the parity descriptor
   * to identify only the chunk of parity associated with the data.  When the access spans
   * exactly one stripe unit boundary and is less than a stripe unit in size, it uses two disjoint
   * regions of the parity unit.  When an access spans more than one stripe unit boundary, it
   * uses all of the parity unit.
   *
   * To better handle the case where stripe units are small, we may eventually want to change
   * the 2nd case so that if the SU size is below some threshold, we just read/write the whole
   * thing instead of breaking it up into two accesses.
   */
  if (asm_p->numStripeUnitsAccessed == 1) 
    {
      int x = (startAddrWithinStripe % layoutPtr->sectorsPerStripeUnit);
      toAdjust->startSector += x;
      toAdjust->raidAddress += x;
      toAdjust->numSector = asm_p->physInfo->numSector;
      RF_ASSERT(toAdjust->numSector != 0);
    } 
  else 
    if (asm_p->numStripeUnitsAccessed == 2 && asm_p->totalSectorsAccessed < layoutPtr->sectorsPerStripeUnit) 
      {
	int x = (startAddrWithinStripe % layoutPtr->sectorsPerStripeUnit);
	
	/* create a second pda and copy the parity map info into it */
	RF_ASSERT(toAdjust->next == NULL);
	new_pda = toAdjust->next = rf_AllocPhysDiskAddr();
	*new_pda = *toAdjust; /* structure assignment */
	new_pda->next = NULL;
	  
	/* adjust the start sector & number of blocks for the first parity pda */
	toAdjust->startSector += x;
	toAdjust->raidAddress += x;
	toAdjust->numSector = rf_RaidAddressOfNextStripeUnitBoundary(layoutPtr, startAddrWithinStripe) - startAddrWithinStripe;
	RF_ASSERT(toAdjust->numSector != 0);

	/* adjust the second pda */
	new_pda->numSector = endAddress - rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, endAddress);
	/*new_pda->raidAddress = rf_RaidAddressOfNextStripeUnitBoundary(layoutPtr, toAdjust->raidAddress);*/
	RF_ASSERT(new_pda->numSector != 0);
      }
}

/*
   Check if a disk has been spared or failed. If spared,
   redirect the I/O. 
   If it has been failed, record it in the asm pointer.
   Fourth arg is whether data or parity.
*/
void rf_ASMCheckStatus(
  RF_Raid_t              *raidPtr,
  RF_PhysDiskAddr_t      *pda_p,
  RF_AccessStripeMap_t   *asm_p,
  RF_RaidDisk_t         **disks,
  int                     parity)
{
  RF_DiskStatus_t dstatus;
  RF_RowCol_t frow, fcol;

  dstatus = disks[pda_p->row][pda_p->col].status;

  if (dstatus == rf_ds_spared) {
    /* if the disk has been spared, redirect access to the spare */
    frow = pda_p->row; fcol = pda_p->col;
    pda_p->row = disks[frow][fcol].spareRow;
    pda_p->col = disks[frow][fcol].spareCol;
  }
  else if (dstatus == rf_ds_dist_spared) {
    /* ditto if disk has been spared to dist spare space */
    RF_RowCol_t or = pda_p->row, oc=pda_p->col;
    RF_SectorNum_t oo = pda_p->startSector;

    if (pda_p -> type == RF_PDA_TYPE_DATA)
      raidPtr->Layout.map->MapSector(raidPtr, pda_p->raidAddress, &pda_p->row, &pda_p->col, &pda_p->startSector, RF_REMAP);
    else
      raidPtr->Layout.map->MapParity(raidPtr, pda_p->raidAddress, &pda_p->row, &pda_p->col, &pda_p->startSector, RF_REMAP);

    if (rf_mapDebug) {
      printf("Redirected r %d c %d o %d -> r%d c %d o %d\n",or,oc,(int)oo,
        pda_p->row,pda_p->col,(int)pda_p->startSector);
    }
  } else if (RF_DEAD_DISK(dstatus)) {
    /* if the disk is inaccessible, mark the failure */
    if (parity)
      asm_p->numParityFailed++;
    else {
      asm_p->numDataFailed++;
#if 0
      /* XXX Do we really want this spewing out on the console? GO */
      printf("DATA_FAILED!\n");
#endif
    }
    asm_p->failedPDAs[asm_p->numFailedPDAs] = pda_p;
    asm_p->numFailedPDAs++;
#if 0
    switch (asm_p->numParityFailed + asm_p->numDataFailed)
      {
      case 1:
	asm_p->failedPDAs[0] = pda_p;
	break;
      case 2:
	asm_p->failedPDAs[1] = pda_p;
      default:
	break;
      }
#endif
  }
  /* the redirected access should never span a stripe unit boundary */
  RF_ASSERT(rf_RaidAddressToStripeUnitID(&raidPtr->Layout,pda_p->raidAddress) ==
	 rf_RaidAddressToStripeUnitID(&raidPtr->Layout,pda_p->raidAddress + pda_p->numSector -1));
  RF_ASSERT(pda_p->col != -1);
}