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Initial revision

/*	$OpenBSD: rf_raid5.c,v 1.4 2002/12/16 07:01:04 tdeval Exp $	*/
/*	$NetBSD: rf_raid5.c,v 1.4 2000/01/08 22:57:30 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.
 */

/*****************************************************************************
 *
 * rf_raid5.c -- Implements RAID Level 5.
 *
 *****************************************************************************/

#include "rf_types.h"
#include "rf_raid.h"
#include "rf_raid5.h"
#include "rf_dag.h"
#include "rf_dagffrd.h"
#include "rf_dagffwr.h"
#include "rf_dagdegrd.h"
#include "rf_dagdegwr.h"
#include "rf_dagutils.h"
#include "rf_general.h"
#include "rf_map.h"
#include "rf_utils.h"

typedef struct RF_Raid5ConfigInfo_s {
	RF_RowCol_t **stripeIdentifier;	/*
					 * Filled in at config time and used
					 * by IdentifyStripe.
					 */
} RF_Raid5ConfigInfo_t;


int
rf_ConfigureRAID5(RF_ShutdownList_t **listp, RF_Raid_t *raidPtr,
    RF_Config_t *cfgPtr)
{
	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
	RF_Raid5ConfigInfo_t *info;
	RF_RowCol_t i, j, startdisk;

	/* Create a RAID level 5 configuration structure. */
	RF_MallocAndAdd(info, sizeof(RF_Raid5ConfigInfo_t),
	    (RF_Raid5ConfigInfo_t *), raidPtr->cleanupList);
	if (info == NULL)
		return (ENOMEM);
	layoutPtr->layoutSpecificInfo = (void *) info;

	RF_ASSERT(raidPtr->numRow == 1);

	/*
	 * The stripe identifier must identify the disks in each stripe, IN
	 * THE ORDER THAT THEY APPEAR IN THE STRIPE.
	 */
	info->stripeIdentifier = rf_make_2d_array(raidPtr->numCol,
	    raidPtr->numCol, raidPtr->cleanupList);
	if (info->stripeIdentifier == NULL)
		return (ENOMEM);
	startdisk = 0;
	for (i = 0; i < raidPtr->numCol; i++) {
		for (j = 0; j < raidPtr->numCol; j++) {
			info->stripeIdentifier[i][j] = (startdisk + j) %
			    raidPtr->numCol;
		}
		if ((--startdisk) < 0)
			startdisk = raidPtr->numCol - 1;
	}

	/* Fill in the remaining layout parameters. */
	layoutPtr->numStripe = layoutPtr->stripeUnitsPerDisk;
	layoutPtr->bytesPerStripeUnit = layoutPtr->sectorsPerStripeUnit <<
	    raidPtr->logBytesPerSector;
	layoutPtr->numDataCol = raidPtr->numCol - 1;
	layoutPtr->dataSectorsPerStripe = layoutPtr->numDataCol *
	    layoutPtr->sectorsPerStripeUnit;
	layoutPtr->numParityCol = 1;
	layoutPtr->dataStripeUnitsPerDisk = layoutPtr->stripeUnitsPerDisk;

	raidPtr->totalSectors = layoutPtr->stripeUnitsPerDisk *
	    layoutPtr->numDataCol * layoutPtr->sectorsPerStripeUnit;

	return (0);
}

int
rf_GetDefaultNumFloatingReconBuffersRAID5(RF_Raid_t *raidPtr)
{
	return (20);
}

RF_HeadSepLimit_t
rf_GetDefaultHeadSepLimitRAID5(RF_Raid_t *raidPtr)
{
	return (10);
}

#if !defined(__NetBSD__) && !defined(__OpenBSD__) && !defined(_KERNEL)
/* Not currently used. */
int
rf_ShutdownRAID5(RF_Raid_t *raidPtr)
{
	return (0);
}
#endif

void
rf_MapSectorRAID5(RF_Raid_t *raidPtr, RF_RaidAddr_t raidSector,
    RF_RowCol_t *row, RF_RowCol_t *col, RF_SectorNum_t *diskSector, int remap)
{
	RF_StripeNum_t SUID = raidSector / raidPtr->Layout.sectorsPerStripeUnit;
	*row = 0;
	*col = (SUID % raidPtr->numCol);
	*diskSector = (SUID / (raidPtr->Layout.numDataCol)) *
	    raidPtr->Layout.sectorsPerStripeUnit +
	    (raidSector % raidPtr->Layout.sectorsPerStripeUnit);
}

void
rf_MapParityRAID5(RF_Raid_t *raidPtr, RF_RaidAddr_t raidSector,
    RF_RowCol_t *row, RF_RowCol_t *col, RF_SectorNum_t *diskSector, int remap)
{
	RF_StripeNum_t SUID = raidSector / raidPtr->Layout.sectorsPerStripeUnit;

	*row = 0;
	*col = raidPtr->Layout.numDataCol -
	    (SUID / raidPtr->Layout.numDataCol) % raidPtr->numCol;
	*diskSector = (SUID / (raidPtr->Layout.numDataCol)) *
	    raidPtr->Layout.sectorsPerStripeUnit +
	    (raidSector % raidPtr->Layout.sectorsPerStripeUnit);
}

void
rf_IdentifyStripeRAID5(RF_Raid_t *raidPtr, RF_RaidAddr_t addr,
    RF_RowCol_t **diskids, RF_RowCol_t *outRow)
{
	RF_StripeNum_t stripeID =
	    rf_RaidAddressToStripeID(&raidPtr->Layout, addr);
	RF_Raid5ConfigInfo_t *info =
	    (RF_Raid5ConfigInfo_t *) raidPtr->Layout.layoutSpecificInfo;

	*outRow = 0;
	*diskids = info->stripeIdentifier[stripeID % raidPtr->numCol];
}

void
rf_MapSIDToPSIDRAID5(RF_RaidLayout_t *layoutPtr, RF_StripeNum_t stripeID,
    RF_StripeNum_t *psID, RF_ReconUnitNum_t *which_ru)
{
	*which_ru = 0;
	*psID = stripeID;
}


/*
 * Select an algorithm for performing an access.  Returns two pointers,
 * one to a function that will return information about the DAG, and
 * another to a function that will create the dag.
 */
void
rf_RaidFiveDagSelect(RF_Raid_t *raidPtr, RF_IoType_t type,
    RF_AccessStripeMap_t *asmap, RF_VoidFuncPtr *createFunc)
{
	RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
	RF_PhysDiskAddr_t *failedPDA = NULL;
	RF_RowCol_t frow, fcol;
	RF_RowStatus_t rstat;
	int prior_recon;

	RF_ASSERT(RF_IO_IS_R_OR_W(type));

	if (asmap->numDataFailed + asmap->numParityFailed > 1) {
		RF_ERRORMSG("Multiple disks failed in a single group !"
		            "  Aborting I/O operation.\n");
		 /* *infoFunc = */ *createFunc = NULL;
		return;
	} else
		if (asmap->numDataFailed + asmap->numParityFailed == 1) {

			/*
			 * If under recon & already reconstructed, redirect
			 * the access to the spare drive and eliminate the
			 * failure indication.
			 */
			failedPDA = asmap->failedPDAs[0];
			frow = failedPDA->row;
			fcol = failedPDA->col;
			rstat = raidPtr->status[failedPDA->row];
			prior_recon = (rstat == rf_rs_reconfigured) || (
			    (rstat == rf_rs_reconstructing) ?
			    rf_CheckRUReconstructed(raidPtr
			     ->reconControl[frow]->reconMap,
			     failedPDA->startSector) : 0);
			if (prior_recon) {
				RF_RowCol_t or = failedPDA->row;
				RF_RowCol_t oc = failedPDA->col;
				RF_SectorNum_t oo = failedPDA->startSector;

				if (layoutPtr->map->flags &
				    RF_DISTRIBUTE_SPARE) {
					/* Redirect to dist spare space. */

					if (failedPDA == asmap->parityInfo) {

						/* Parity has failed. */
						(layoutPtr->map->MapParity)
						    (raidPtr,
						     failedPDA->raidAddress,
						     &failedPDA->row,
						     &failedPDA->col,
						     &failedPDA->startSector,
						     RF_REMAP);

						if (asmap->parityInfo->next) {
							/*
							 * Redir 2nd component,
							 * if any.
							 */
							RF_PhysDiskAddr_t *p =
							    asmap
							     ->parityInfo->next;
							RF_SectorNum_t SUoffs =
							    p->startSector %
						layoutPtr->sectorsPerStripeUnit;
							p->row = failedPDA->row;
							p->col = failedPDA->col;
							/*
							 * Cheating:
							 * startSector is not
							 * really a RAID
							 * address.
							 */
							p->startSector =
					rf_RaidAddressOfPrevStripeUnitBoundary(
					    layoutPtr, failedPDA->startSector) +
							    SUoffs;
						}
					} else
						if (asmap->parityInfo->next &&
						    failedPDA ==
						    asmap->parityInfo->next) {
							/*
							 * Should never happen.
							 */
							RF_ASSERT(0);
						} else {
							/* Data has failed. */
							(layoutPtr->map
							 ->MapSector) (raidPtr,
							 failedPDA->raidAddress,
							    &failedPDA->row,
							    &failedPDA->col,
							&failedPDA->startSector,
							    RF_REMAP);
						}

				} else {
					/* Redirect to dedicated spare space. */

					failedPDA->row =
					    raidPtr->Disks[frow][fcol].spareRow;
					failedPDA->col =
					    raidPtr->Disks[frow][fcol].spareCol;

					/*
					 * The parity may have two distinct
					 * components, both of which may need
					 * to be redirected.
					 */
					if (asmap->parityInfo->next) {
						if (failedPDA ==
						    asmap->parityInfo) {
							failedPDA->next->row =
							    failedPDA->row;
							failedPDA->next->col =
							    failedPDA->col;
						} else {
							if (failedPDA ==
							    asmap->parityInfo
							     ->next) {
								/*
								 * Paranoid:
								 * Should never
								 * occur.
								 */
								asmap
								 ->parityInfo
								 ->row =
								 failedPDA->row;
								asmap
								 ->parityInfo
								 ->col =
								 failedPDA->col;
							}
						}
					}
				}

				RF_ASSERT(failedPDA->col != -1);

				if (rf_dagDebug || rf_mapDebug) {
					printf("raid%d: Redirected type '%c'"
					       " r %d c %d o %ld -> r %d c %d"
					       " o %ld\n", raidPtr->raidid,
					       type, or, oc, (long) oo,
					       failedPDA->row, failedPDA->col,
					       (long) failedPDA->startSector);
				}
				asmap->numDataFailed = asmap->numParityFailed
				                     = 0;
			}
		}
	/*
	 * All DAGs begin/end with block/unblock node. Therefore, hdrSucc &
	 * termAnt counts should always be 1. Also, these counts should not be
	 * visible outside DAG creation routines - manipulating the counts
	 * here should be removed.
	 */
	if (type == RF_IO_TYPE_READ) {
		if (asmap->numDataFailed == 0)
			*createFunc = (RF_VoidFuncPtr)
			    rf_CreateFaultFreeReadDAG;
		else
			*createFunc = (RF_VoidFuncPtr)
			    rf_CreateRaidFiveDegradedReadDAG;
	} else {
		/*
		 * If mirroring, always use large writes. If the access
		 * requires two distinct parity updates, always do a small
		 * write. If the stripe contains a failure but the access
		 * does not, do a small write. The first conditional
		 * (numStripeUnitsAccessed <= numDataCol/2) uses a
		 * less-than-or-equal rather than just a less-than because
		 * when G is 3 or 4, numDataCol/2 is 1, and I want
		 * single-stripe-unit updates to use just one disk.
		 */
		if ((asmap->numDataFailed + asmap->numParityFailed) == 0) {
			if (rf_suppressLocksAndLargeWrites ||
			    (((asmap->numStripeUnitsAccessed <=
			       (layoutPtr->numDataCol / 2)) &&
			      (layoutPtr->numDataCol != 1)) ||
			     (asmap->parityInfo->next != NULL) ||
			     rf_CheckStripeForFailures(raidPtr, asmap))) {
				*createFunc = (RF_VoidFuncPtr)
				    rf_CreateSmallWriteDAG;
			} else
				*createFunc = (RF_VoidFuncPtr)
				    rf_CreateLargeWriteDAG;
		} else {
			if (asmap->numParityFailed == 1)
				*createFunc = (RF_VoidFuncPtr)
				    rf_CreateNonRedundantWriteDAG;
			else
				if (asmap->numStripeUnitsAccessed != 1 &&
				    failedPDA->numSector !=
				    layoutPtr->sectorsPerStripeUnit)
					*createFunc = NULL;
				else
					*createFunc = (RF_VoidFuncPtr)
					    rf_CreateDegradedWriteDAG;
		}
	}
}