xref: /src/sys/dev/raidframe/rf_map.c

/*	$NetBSD: rf_map.c,v 1.50.14.1 2021/08/01 22:42:31 thorpej 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 (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.
 */

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

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rf_map.c,v 1.50.14.1 2021/08/01 22:42:31 thorpej Exp $");

#include <dev/raidframe/raidframevar.h>

#include "rf_threadstuff.h"
#include "rf_raid.h"
#include "rf_general.h"
#include "rf_map.h"
#include "rf_shutdown.h"

static void rf_FreePDAList(RF_Raid_t *raidPtr, RF_PhysDiskAddr_t *pda_list);
static void rf_FreeASMList(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asm_list);

/***************************************************************************
 *
 * 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
 *
 * raidAddress - starting address in RAID address space
 * numBlocks   - number of blocks in RAID address space to access
 * buffer      - buffer to supply/receive data
 * remap       - 1 => remap address to spare space
 ***************************************************************************/

RF_AccessStripeMapHeader_t *
rf_MapAccess(RF_Raid_t *raidPtr, RF_RaidAddr_t raidAddress,
	     RF_SectorCount_t numBlocks, void *buffer, int remap)
{
	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;
	/* we'll change raidAddress along the way */
	RF_RaidAddr_t startAddress = raidAddress;
	RF_RaidAddr_t endAddress = raidAddress + numBlocks;
	RF_RaidDisk_t *disks = raidPtr->Disks;
	RF_PhysDiskAddr_t *pda_p;
#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
	RF_PhysDiskAddr_t *pda_q;
#endif
	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(raidPtr, totStripes);

	/* may also need pda(s) per stripe for parity */
	pdaList = rf_AllocPDAList(raidPtr, lastSUID - SUID + 1 +
				  faultsTolerated * totStripes);


	if (raidAddress + numBlocks > raidPtr->totalSectors) {
		RF_ERRORMSG1("Unable to map access because offset (%d) was invalid\n",
		    (int) raidAddress);
		return (NULL);
	}
#if RF_DEBUG_MAP
	if (rf_mapDebug)
		rf_PrintRaidAddressInfo(raidPtr, raidAddress, numBlocks);
#endif
	for (; raidAddress < endAddress;) {
		/* make the next stripe structure */
		RF_ASSERT(asmList);
		t_asm = asmList;
		asmList = asmList->next;
		memset(t_asm, 0, sizeof(*t_asm));
		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;

		/* Raid addr of start of portion of access that is
                   within this stripe */
		startAddrWithinStripe = raidAddress;

		for (; raidAddress < stripeEndAddress;) {
			RF_ASSERT(pdaList);
			t_pda = pdaList;
			pdaList = pdaList->next;
			memset(t_pda, 0, sizeof(*t_pda));
			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->col),
						     &(pda_p->startSector),
						     remap);

			/* mark any failures we find.  failedPDA is
			 * don't-care if there is more than one
			 * failure */

			/* the RAID address corresponding to this
                           physical diskaddress */
			pda_p->raidAddress = raidAddress;
			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 = (char *)buffer + rf_RaidAddressToByte(raidPtr, (raidAddress - startAddress));
			asm_p->totalSectorsAccessed += pda_p->numSector;
			asm_p->numStripeUnitsAccessed++;

			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;
			memset(t_pda, 0, sizeof(*t_pda));
			pda_p = asm_p->parityInfo = t_pda;
			pda_p->type = RF_PDA_TYPE_PARITY;
			(layoutPtr->map->MapParity) (raidPtr, rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe),
			    &(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(raidPtr, asm_p->parityInfo, startAddrWithinStripe, endAddress, layoutPtr, asm_p);

			break;
#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
		case 2:	/* two fault tolerant */
			RF_ASSERT(pdaList && pdaList->next);
			t_pda = pdaList;
			pdaList = pdaList->next;
			memset(t_pda, 0, sizeof(*t_pda));
			pda_p = asm_p->parityInfo = t_pda;
			pda_p->type = RF_PDA_TYPE_PARITY;
			t_pda = pdaList;
			pdaList = pdaList->next;
			memset(t_pda, 0, sizeof(*t_pda));
			pda_q = asm_p->qInfo = t_pda;
			pda_q->type = RF_PDA_TYPE_Q;
			(layoutPtr->map->MapParity) (raidPtr, rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe),
			    &(pda_p->col), &(pda_p->startSector), remap);
			(layoutPtr->map->MapQ) (raidPtr, rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, startAddrWithinStripe),
			    &(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(raidPtr, asm_p->parityInfo, startAddrWithinStripe, endAddress, layoutPtr, asm_p);
			rf_ASMParityAdjust(raidPtr, asm_p->qInfo, startAddrWithinStripe, endAddress, layoutPtr, asm_p);
			break;
#endif
		}
	}
	RF_ASSERT(asmList == NULL && pdaList == NULL);
	/* make the header structure */
	asm_hdr = rf_AllocAccessStripeMapHeader(raidPtr);
	RF_ASSERT(numStripes == totStripes);
	asm_hdr->numStripes = numStripes;
	asm_hdr->stripeMap = asm_list;

#if RF_DEBUG_MAP
	if (rf_mapDebug)
		rf_PrintAccessStripeMap(asm_hdr);
#endif
	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(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 = 0;
		asmap->numParityFailed = 0;
		asmap->numQFailed = 0;
		asmap->numFailedPDAs = 0;
		memset(asmap->failedPDAs, 0,
		    RF_MAX_FAILED_PDA * sizeof(*asmap->failedPDAs));
		for (pda = asmap->physInfo; pda; pda = pda->next) {
			if (RF_DEAD_DISK(disks[pda->col].status)) {
				asmap->numDataFailed++;
				asmap->failedPDAs[asmap->numFailedPDAs] = pda;
				asmap->numFailedPDAs++;
			}
		}
		pda = asmap->parityInfo;
		if (pda && RF_DEAD_DISK(disks[pda->col].status)) {
			asmap->numParityFailed++;
			asmap->failedPDAs[asmap->numFailedPDAs] = pda;
			asmap->numFailedPDAs++;
		}
		pda = asmap->qInfo;
		if (pda && RF_DEAD_DISK(disks[pda->col].status)) {
			asmap->numQFailed++;
			asmap->failedPDAs[asmap->numFailedPDAs] = pda;
			asmap->numFailedPDAs++;
		}
	}
}

/***************************************************************************
 *
 * 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.
 *
 ***************************************************************************/

#define RF_MAX_FREE_ASMHDR 128
#define RF_MIN_FREE_ASMHDR  32

#define RF_MAX_FREE_ASM 192
#define RF_MIN_FREE_ASM  64

#define RF_MAX_FREE_PDA 192
#define RF_MIN_FREE_PDA  64

#define RF_MAX_FREE_ASMHLE 64
#define RF_MIN_FREE_ASMHLE 16

#define RF_MAX_FREE_FSS 128
#define RF_MIN_FREE_FSS  32

#define RF_MAX_FREE_VFPLE 128
#define RF_MIN_FREE_VFPLE  32

#define RF_MAX_FREE_VPLE 128
#define RF_MIN_FREE_VPLE  32


/* 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(void *arg)
{
	RF_Raid_t *raidPtr;

	raidPtr = (RF_Raid_t *) arg;

	pool_destroy(&raidPtr->pools.asm_hdr);
	pool_destroy(&raidPtr->pools.asmap);
	pool_destroy(&raidPtr->pools.asmhle);
	pool_destroy(&raidPtr->pools.pda);
	pool_destroy(&raidPtr->pools.fss);
	pool_destroy(&raidPtr->pools.vfple);
	pool_destroy(&raidPtr->pools.vple);
}

int
rf_ConfigureMapModule(RF_ShutdownList_t **listp, RF_Raid_t *raidPtr,
		      RF_Config_t *cfgPtr)
{

	rf_pool_init(raidPtr, raidPtr->poolNames.asm_hdr, &raidPtr->pools.asm_hdr, sizeof(RF_AccessStripeMapHeader_t),
		     "asmhdr", RF_MIN_FREE_ASMHDR, RF_MAX_FREE_ASMHDR);
	rf_pool_init(raidPtr, raidPtr->poolNames.asmap, &raidPtr->pools.asmap, sizeof(RF_AccessStripeMap_t),
		     "asmap", RF_MIN_FREE_ASM, RF_MAX_FREE_ASM);
	rf_pool_init(raidPtr, raidPtr->poolNames.asmhle, &raidPtr->pools.asmhle, sizeof(RF_ASMHeaderListElem_t),
		     "asmhle", RF_MIN_FREE_ASMHLE, RF_MAX_FREE_ASMHLE);
	rf_pool_init(raidPtr, raidPtr->poolNames.pda, &raidPtr->pools.pda, sizeof(RF_PhysDiskAddr_t),
		     "pda", RF_MIN_FREE_PDA, RF_MAX_FREE_PDA);
	rf_pool_init(raidPtr, raidPtr->poolNames.fss, &raidPtr->pools.fss, sizeof(RF_FailedStripe_t),
		     "fss", RF_MIN_FREE_FSS, RF_MAX_FREE_FSS);
	rf_pool_init(raidPtr, raidPtr->poolNames.vfple, &raidPtr->pools.vfple, sizeof(RF_VoidFunctionPointerListElem_t),
		     "vfple", RF_MIN_FREE_VFPLE, RF_MAX_FREE_VFPLE);
	rf_pool_init(raidPtr, raidPtr->poolNames.vple, &raidPtr->pools.vple, sizeof(RF_VoidPointerListElem_t),
		     "vple", RF_MIN_FREE_VPLE, RF_MAX_FREE_VPLE);
	rf_ShutdownCreate(listp, rf_ShutdownMapModule, raidPtr);

	return (0);
}

RF_AccessStripeMapHeader_t *
rf_AllocAccessStripeMapHeader(RF_Raid_t *raidPtr)
{
	return pool_get(&raidPtr->pools.asm_hdr, PR_WAITOK | PR_ZERO);
}

void
rf_FreeAccessStripeMapHeader(RF_Raid_t *raidPtr, RF_AccessStripeMapHeader_t *p)
{
	pool_put(&raidPtr->pools.asm_hdr, p);
}


RF_VoidFunctionPointerListElem_t *
rf_AllocVFPListElem(RF_Raid_t *raidPtr)
{
	return pool_get(&raidPtr->pools.vfple, PR_WAITOK | PR_ZERO);
}

void
rf_FreeVFPListElem(RF_Raid_t *raidPtr, RF_VoidFunctionPointerListElem_t *p)
{

	pool_put(&raidPtr->pools.vfple, p);
}


RF_VoidPointerListElem_t *
rf_AllocVPListElem(RF_Raid_t *raidPtr)
{
	return pool_get(&raidPtr->pools.vple, PR_WAITOK | PR_ZERO);
}

void
rf_FreeVPListElem(RF_Raid_t *raidPtr, RF_VoidPointerListElem_t *p)
{

	pool_put(&raidPtr->pools.vple, p);
}

RF_ASMHeaderListElem_t *
rf_AllocASMHeaderListElem(RF_Raid_t *raidPtr)
{
	return pool_get(&raidPtr->pools.asmhle, PR_WAITOK | PR_ZERO);
}

void
rf_FreeASMHeaderListElem(RF_Raid_t *raidPtr, RF_ASMHeaderListElem_t *p)
{

	pool_put(&raidPtr->pools.asmhle, p);
}

RF_FailedStripe_t *
rf_AllocFailedStripeStruct(RF_Raid_t *raidPtr)
{
	return pool_get(&raidPtr->pools.fss, PR_WAITOK | PR_ZERO);
}

void
rf_FreeFailedStripeStruct(RF_Raid_t *raidPtr, RF_FailedStripe_t *p)
{
	pool_put(&raidPtr->pools.fss, p);
}





RF_PhysDiskAddr_t *
rf_AllocPhysDiskAddr(RF_Raid_t *raidPtr)
{
	return pool_get(&raidPtr->pools.pda, PR_WAITOK | PR_ZERO);
}
/* 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(RF_Raid_t *raidPtr, int count)
{
	RF_PhysDiskAddr_t *p, *prev;
	int i;

	p = NULL;
	prev = NULL;
	for (i = 0; i < count; i++) {
		p = pool_get(&raidPtr->pools.pda, PR_WAITOK);
		p->next = prev;
		prev = p;
	}

	return (p);
}

void
rf_FreePhysDiskAddr(RF_Raid_t *raidPtr, RF_PhysDiskAddr_t *p)
{
	pool_put(&raidPtr->pools.pda, p);
}

static void
rf_FreePDAList(RF_Raid_t *raidPtr, RF_PhysDiskAddr_t *pda_list)
{
	RF_PhysDiskAddr_t *p, *tmp;

	p=pda_list;
	while (p) {
		tmp = p->next;
		pool_put(&raidPtr->pools.pda, p);
		p = tmp;
	}
}

/* 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(RF_Raid_t *raidPtr, int count)
{
	RF_AccessStripeMap_t *p, *prev;
	int i;

	p = NULL;
	prev = NULL;
	for (i = 0; i < count; i++) {
		p = pool_get(&raidPtr->pools.asmap, PR_WAITOK);
		p->next = prev;
		prev = p;
	}
	return (p);
}

static void
rf_FreeASMList(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asm_list)
{
	RF_AccessStripeMap_t *p, *tmp;

	p=asm_list;
	while (p) {
		tmp = p->next;
		pool_put(&raidPtr->pools.asmap, p);
		p = tmp;
	}
}

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

	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;
	}

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

	if (pdaList)
		rf_FreePDAList(raidPtr, pdaList);
	rf_FreeASMList(raidPtr, hdr->stripeMap);
	rf_FreeAccessStripeMapHeader(raidPtr, 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(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asmap)
{
	RF_RowCol_t tcol, pcol, *diskids, i;
	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
	RF_StripeCount_t stripeOffset;
	int     numFailures;
	RF_RaidAddr_t sosAddr;
	RF_SectorNum_t diskOffset, poffset;

	/* quick out in the fault-free case.  */
	rf_lock_mutex2(raidPtr->mutex);
	numFailures = raidPtr->numFailures;
	rf_unlock_mutex2(raidPtr->mutex);
	if (numFailures == 0)
		return (0);

	sosAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr,
						     asmap->raidAddress);
	(layoutPtr->map->IdentifyStripe) (raidPtr, asmap->raidAddress,
					  &diskids);
	(layoutPtr->map->MapParity) (raidPtr, asmap->raidAddress,
				     &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[diskids[i]].status)) {
				if (raidPtr->status != rf_rs_reconstructing)
					return (1);
				RF_ASSERT(raidPtr->reconControl->fcol == diskids[i]);
				layoutPtr->map->MapSector(raidPtr,
				    sosAddr + stripeOffset * layoutPtr->sectorsPerStripeUnit,
				    &tcol, &diskOffset, 0);
				RF_ASSERT(tcol == diskids[i]);
				if (!rf_CheckRUReconstructed(raidPtr->reconControl->reconMap, diskOffset))
					return (1);
				asmap->flags |= RF_ASM_REDIR_LARGE_WRITE;
				return (0);
			}
			stripeOffset++;
		}
	}
	return (0);
}
#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0) || (RF_INCLUDE_EVENODD >0)
/*
   return the number of failed data units in the stripe.
*/

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

	/* quick out in the fault-free case.  */
	rf_lock_mutex2(raidPtr->mutex);
	numFailures = raidPtr->numFailures;
	rf_unlock_mutex2(raidPtr->mutex);
	if (numFailures == 0)
		return (0);
	numFailures = 0;

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

	return numFailures;
}
#endif

/****************************************************************************
 *
 * debug routines
 *
 ***************************************************************************/
#if RF_DEBUG_MAP
void
rf_PrintAccessStripeMap(RF_AccessStripeMapHeader_t *asm_h)
{
	rf_PrintFullAccessStripeMap(asm_h, 0);
}
#endif

/* prbuf - flag to print buffer pointers */
void
rf_PrintFullAccessStripeMap(RF_AccessStripeMapHeader_t *asm_h, int prbuf)
{
	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 [c%d s%d-%d", 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(", c%d s%d-%d", 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 c%d s%d-%d ", 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: c%d s%d-%d]\n", p->col,
				    (int) p->startSector, (int) (p->startSector + p->numSector - 1));
	}
}

#if RF_MAP_DEBUG
void
rf_PrintRaidAddressInfo(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));
}
#endif
/* 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_Raid_t *raidPtr,
		   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);
			/* the following will get freed in rf_FreeAccessStripeMap() via
			   rf_FreePDAList() */
			new_pda = toAdjust->next = rf_AllocPhysDiskAddr(raidPtr);
			*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.  Fifth
 * 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 fcol;

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

	if (dstatus == rf_ds_spared) {
		/* if the disk has been spared, redirect access to the spare */
		fcol = pda_p->col;
		pda_p->col = disks[fcol].spareCol;
	} else
		if (dstatus == rf_ds_dist_spared) {
			/* ditto if disk has been spared to dist spare space */
#if RF_DEBUG_MAP
			RF_RowCol_t oc = pda_p->col;
			RF_SectorNum_t oo = pda_p->startSector;
#endif
			if (pda_p->type == RF_PDA_TYPE_DATA)
				raidPtr->Layout.map->MapSector(raidPtr, pda_p->raidAddress, &pda_p->col, &pda_p->startSector, RF_REMAP);
			else
				raidPtr->Layout.map->MapParity(raidPtr, pda_p->raidAddress, &pda_p->col, &pda_p->startSector, RF_REMAP);

#if RF_DEBUG_MAP
			if (rf_mapDebug) {
				printf("Redirected c %d o %d -> c %d o %d\n", oc, (int) oo,
				    pda_p->col, (int) pda_p->startSector);
			}
#endif
		} else
			if (RF_DEAD_DISK(dstatus)) {
				/* if the disk is inaccessible, mark the
				 * failure */
				if (parity)
					asm_p->numParityFailed++;
				else {
					asm_p->numDataFailed++;
				}
				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);
}