/* $NetBSD: rf_dagutils.c,v 1.56 2019/02/10 17:13:33 christos Exp $ */ /* * Copyright (c) 1995 Carnegie-Mellon University. * All rights reserved. * * Authors: Mark Holland, William V. Courtright II, Jim Zelenka * * 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_dagutils.c -- utility routines for manipulating dags * *****************************************************************************/ #include __KERNEL_RCSID(0, "$NetBSD: rf_dagutils.c,v 1.56 2019/02/10 17:13:33 christos Exp $"); #include #include "rf_archs.h" #include "rf_threadstuff.h" #include "rf_raid.h" #include "rf_dag.h" #include "rf_dagutils.h" #include "rf_dagfuncs.h" #include "rf_general.h" #include "rf_map.h" #include "rf_shutdown.h" #define SNUM_DIFF(_a_,_b_) (((_a_)>(_b_))?((_a_)-(_b_)):((_b_)-(_a_))) const RF_RedFuncs_t rf_xorFuncs = { rf_RegularXorFunc, "Reg Xr", rf_SimpleXorFunc, "Simple Xr"}; const RF_RedFuncs_t rf_xorRecoveryFuncs = { rf_RecoveryXorFunc, "Recovery Xr", rf_RecoveryXorFunc, "Recovery Xr"}; #if RF_DEBUG_VALIDATE_DAG static void rf_RecurPrintDAG(RF_DagNode_t *, int, int); static void rf_PrintDAG(RF_DagHeader_t *); static int rf_ValidateBranch(RF_DagNode_t *, int *, int *, RF_DagNode_t **, int); static void rf_ValidateBranchVisitedBits(RF_DagNode_t *, int, int); static void rf_ValidateVisitedBits(RF_DagHeader_t *); #endif /* RF_DEBUG_VALIDATE_DAG */ /* The maximum number of nodes in a DAG is bounded by (2 * raidPtr->Layout->numDataCol) + (1 * layoutPtr->numParityCol) + (1 * 2 * layoutPtr->numParityCol) + 3 which is: 2*RF_MAXCOL+1*2+1*2*2+3 For RF_MAXCOL of 40, this works out to 89. We use this value to provide an estimate on the maximum size needed for RF_DAGPCACHE_SIZE. For RF_MAXCOL of 40, this structure would be 534 bytes. Too much to have on-hand in a RF_DagNode_t, but should be ok to have a few kicking around. */ #define RF_DAGPCACHE_SIZE ((2*RF_MAXCOL+1*2+1*2*2+3) *(RF_MAX(sizeof(RF_DagParam_t), sizeof(RF_DagNode_t *)))) /****************************************************************************** * * InitNode - initialize a dag node * * the size of the propList array is always the same as that of the * successors array. * *****************************************************************************/ void rf_InitNode(RF_DagNode_t *node, RF_NodeStatus_t initstatus, int commit, int (*doFunc) (RF_DagNode_t *node), int (*undoFunc) (RF_DagNode_t *node), int (*wakeFunc) (RF_DagNode_t *node, int status), int nSucc, int nAnte, int nParam, int nResult, RF_DagHeader_t *hdr, const char *name, RF_AllocListElem_t *alist) { void **ptrs; int nptrs; if (nAnte > RF_MAX_ANTECEDENTS) RF_PANIC(); node->status = initstatus; node->commitNode = commit; node->doFunc = doFunc; node->undoFunc = undoFunc; node->wakeFunc = wakeFunc; node->numParams = nParam; node->numResults = nResult; node->numAntecedents = nAnte; node->numAntDone = 0; node->next = NULL; /* node->list_next = NULL */ /* Don't touch this here! It may already be in use by the caller! */ node->numSuccedents = nSucc; node->name = name; node->dagHdr = hdr; node->big_dag_ptrs = NULL; node->big_dag_params = NULL; node->visited = 0; /* allocate all the pointers with one call to malloc */ nptrs = nSucc + nAnte + nResult + nSucc; if (nptrs <= RF_DAG_PTRCACHESIZE) { /* * The dag_ptrs field of the node is basically some scribble * space to be used here. We could get rid of it, and always * allocate the range of pointers, but that's expensive. So, * we pick a "common case" size for the pointer cache. Hopefully, * we'll find that: * (1) Generally, nptrs doesn't exceed RF_DAG_PTRCACHESIZE by * only a little bit (least efficient case) * (2) Generally, ntprs isn't a lot less than RF_DAG_PTRCACHESIZE * (wasted memory) */ ptrs = (void **) node->dag_ptrs; } else if (nptrs <= (RF_DAGPCACHE_SIZE / sizeof(RF_DagNode_t *))) { node->big_dag_ptrs = rf_AllocDAGPCache(); ptrs = (void **) node->big_dag_ptrs; } else { ptrs = RF_MallocAndAdd(nptrs * sizeof(*ptrs), alist); } node->succedents = (nSucc) ? (RF_DagNode_t **) ptrs : NULL; node->antecedents = (nAnte) ? (RF_DagNode_t **) (ptrs + nSucc) : NULL; node->results = (nResult) ? (void **) (ptrs + nSucc + nAnte) : NULL; node->propList = (nSucc) ? (RF_PropHeader_t **) (ptrs + nSucc + nAnte + nResult) : NULL; if (nParam) { if (nParam <= RF_DAG_PARAMCACHESIZE) { node->params = (RF_DagParam_t *) node->dag_params; } else if (nParam <= (RF_DAGPCACHE_SIZE / sizeof(RF_DagParam_t))) { node->big_dag_params = rf_AllocDAGPCache(); node->params = node->big_dag_params; } else { node->params = RF_MallocAndAdd( nParam * sizeof(*node->params), alist); } } else { node->params = NULL; } } /****************************************************************************** * * allocation and deallocation routines * *****************************************************************************/ void rf_FreeDAG(RF_DagHeader_t *dag_h) { RF_AccessStripeMapHeader_t *asmap, *t_asmap; RF_PhysDiskAddr_t *pda; RF_DagNode_t *tmpnode; RF_DagHeader_t *nextDag; while (dag_h) { nextDag = dag_h->next; rf_FreeAllocList(dag_h->allocList); for (asmap = dag_h->asmList; asmap;) { t_asmap = asmap; asmap = asmap->next; rf_FreeAccessStripeMap(t_asmap); } while (dag_h->pda_cleanup_list) { pda = dag_h->pda_cleanup_list; dag_h->pda_cleanup_list = dag_h->pda_cleanup_list->next; rf_FreePhysDiskAddr(pda); } while (dag_h->nodes) { tmpnode = dag_h->nodes; dag_h->nodes = dag_h->nodes->list_next; rf_FreeDAGNode(tmpnode); } rf_FreeDAGHeader(dag_h); dag_h = nextDag; } } #define RF_MAX_FREE_DAGH 128 #define RF_MIN_FREE_DAGH 32 #define RF_MAX_FREE_DAGNODE 512 /* XXX Tune this... */ #define RF_MIN_FREE_DAGNODE 128 /* XXX Tune this... */ #define RF_MAX_FREE_DAGLIST 128 #define RF_MIN_FREE_DAGLIST 32 #define RF_MAX_FREE_DAGPCACHE 128 #define RF_MIN_FREE_DAGPCACHE 8 #define RF_MAX_FREE_FUNCLIST 128 #define RF_MIN_FREE_FUNCLIST 32 #define RF_MAX_FREE_BUFFERS 128 #define RF_MIN_FREE_BUFFERS 32 static void rf_ShutdownDAGs(void *); static void rf_ShutdownDAGs(void *ignored) { pool_destroy(&rf_pools.dagh); pool_destroy(&rf_pools.dagnode); pool_destroy(&rf_pools.daglist); pool_destroy(&rf_pools.dagpcache); pool_destroy(&rf_pools.funclist); } int rf_ConfigureDAGs(RF_ShutdownList_t **listp) { rf_pool_init(&rf_pools.dagnode, sizeof(RF_DagNode_t), "rf_dagnode_pl", RF_MIN_FREE_DAGNODE, RF_MAX_FREE_DAGNODE); rf_pool_init(&rf_pools.dagh, sizeof(RF_DagHeader_t), "rf_dagh_pl", RF_MIN_FREE_DAGH, RF_MAX_FREE_DAGH); rf_pool_init(&rf_pools.daglist, sizeof(RF_DagList_t), "rf_daglist_pl", RF_MIN_FREE_DAGLIST, RF_MAX_FREE_DAGLIST); rf_pool_init(&rf_pools.dagpcache, RF_DAGPCACHE_SIZE, "rf_dagpcache_pl", RF_MIN_FREE_DAGPCACHE, RF_MAX_FREE_DAGPCACHE); rf_pool_init(&rf_pools.funclist, sizeof(RF_FuncList_t), "rf_funclist_pl", RF_MIN_FREE_FUNCLIST, RF_MAX_FREE_FUNCLIST); rf_ShutdownCreate(listp, rf_ShutdownDAGs, NULL); return (0); } RF_DagHeader_t * rf_AllocDAGHeader(void) { return pool_get(&rf_pools.dagh, PR_WAITOK | PR_ZERO); } void rf_FreeDAGHeader(RF_DagHeader_t * dh) { pool_put(&rf_pools.dagh, dh); } RF_DagNode_t * rf_AllocDAGNode(void) { return pool_get(&rf_pools.dagnode, PR_WAITOK | PR_ZERO); } void rf_FreeDAGNode(RF_DagNode_t *node) { if (node->big_dag_ptrs) { rf_FreeDAGPCache(node->big_dag_ptrs); } if (node->big_dag_params) { rf_FreeDAGPCache(node->big_dag_params); } pool_put(&rf_pools.dagnode, node); } RF_DagList_t * rf_AllocDAGList(void) { return pool_get(&rf_pools.daglist, PR_WAITOK | PR_ZERO); } void rf_FreeDAGList(RF_DagList_t *dagList) { pool_put(&rf_pools.daglist, dagList); } void * rf_AllocDAGPCache(void) { return pool_get(&rf_pools.dagpcache, PR_WAITOK | PR_ZERO); } void rf_FreeDAGPCache(void *p) { pool_put(&rf_pools.dagpcache, p); } RF_FuncList_t * rf_AllocFuncList(void) { return pool_get(&rf_pools.funclist, PR_WAITOK | PR_ZERO); } void rf_FreeFuncList(RF_FuncList_t *funcList) { pool_put(&rf_pools.funclist, funcList); } /* allocates a stripe buffer -- a buffer large enough to hold all the data in an entire stripe. */ void * rf_AllocStripeBuffer(RF_Raid_t *raidPtr, RF_DagHeader_t *dag_h, int size) { RF_VoidPointerListElem_t *vple; void *p; RF_ASSERT((size <= (raidPtr->numCol * (raidPtr->Layout.sectorsPerStripeUnit << raidPtr->logBytesPerSector)))); p = malloc( raidPtr->numCol * (raidPtr->Layout.sectorsPerStripeUnit << raidPtr->logBytesPerSector), M_RAIDFRAME, M_NOWAIT); if (!p) { rf_lock_mutex2(raidPtr->mutex); if (raidPtr->stripebuf_count > 0) { vple = raidPtr->stripebuf; raidPtr->stripebuf = vple->next; p = vple->p; rf_FreeVPListElem(vple); raidPtr->stripebuf_count--; } else { #ifdef DIAGNOSTIC printf("raid%d: Help! Out of emergency full-stripe buffers!\n", raidPtr->raidid); #endif } rf_unlock_mutex2(raidPtr->mutex); if (!p) { /* We didn't get a buffer... not much we can do other than wait, and hope that someone frees up memory for us.. */ p = malloc( raidPtr->numCol * (raidPtr->Layout.sectorsPerStripeUnit << raidPtr->logBytesPerSector), M_RAIDFRAME, M_WAITOK); } } memset(p, 0, raidPtr->numCol * (raidPtr->Layout.sectorsPerStripeUnit << raidPtr->logBytesPerSector)); vple = rf_AllocVPListElem(); vple->p = p; vple->next = dag_h->desc->stripebufs; dag_h->desc->stripebufs = vple; return (p); } void rf_FreeStripeBuffer(RF_Raid_t *raidPtr, RF_VoidPointerListElem_t *vple) { rf_lock_mutex2(raidPtr->mutex); if (raidPtr->stripebuf_count < raidPtr->numEmergencyStripeBuffers) { /* just tack it in */ vple->next = raidPtr->stripebuf; raidPtr->stripebuf = vple; raidPtr->stripebuf_count++; } else { free(vple->p, M_RAIDFRAME); rf_FreeVPListElem(vple); } rf_unlock_mutex2(raidPtr->mutex); } /* allocates a buffer big enough to hold the data described by the caller (ie. the data of the associated PDA). Glue this buffer into our dag_h cleanup structure. */ void * rf_AllocBuffer(RF_Raid_t *raidPtr, RF_DagHeader_t *dag_h, int size) { RF_VoidPointerListElem_t *vple; void *p; p = rf_AllocIOBuffer(raidPtr, size); vple = rf_AllocVPListElem(); vple->p = p; vple->next = dag_h->desc->iobufs; dag_h->desc->iobufs = vple; return (p); } void * rf_AllocIOBuffer(RF_Raid_t *raidPtr, int size) { RF_VoidPointerListElem_t *vple; void *p; RF_ASSERT((size <= (raidPtr->Layout.sectorsPerStripeUnit << raidPtr->logBytesPerSector))); p = malloc( raidPtr->Layout.sectorsPerStripeUnit << raidPtr->logBytesPerSector, M_RAIDFRAME, M_NOWAIT); if (!p) { rf_lock_mutex2(raidPtr->mutex); if (raidPtr->iobuf_count > 0) { vple = raidPtr->iobuf; raidPtr->iobuf = vple->next; p = vple->p; rf_FreeVPListElem(vple); raidPtr->iobuf_count--; } else { #ifdef DIAGNOSTIC printf("raid%d: Help! Out of emergency buffers!\n", raidPtr->raidid); #endif } rf_unlock_mutex2(raidPtr->mutex); if (!p) { /* We didn't get a buffer... not much we can do other than wait, and hope that someone frees up memory for us.. */ p = malloc( raidPtr->Layout.sectorsPerStripeUnit << raidPtr->logBytesPerSector, M_RAIDFRAME, M_WAITOK); } } memset(p, 0, raidPtr->Layout.sectorsPerStripeUnit << raidPtr->logBytesPerSector); return (p); } void rf_FreeIOBuffer(RF_Raid_t *raidPtr, RF_VoidPointerListElem_t *vple) { rf_lock_mutex2(raidPtr->mutex); if (raidPtr->iobuf_count < raidPtr->numEmergencyBuffers) { /* just tack it in */ vple->next = raidPtr->iobuf; raidPtr->iobuf = vple; raidPtr->iobuf_count++; } else { free(vple->p, M_RAIDFRAME); rf_FreeVPListElem(vple); } rf_unlock_mutex2(raidPtr->mutex); } #if RF_DEBUG_VALIDATE_DAG /****************************************************************************** * * debug routines * *****************************************************************************/ char * rf_NodeStatusString(RF_DagNode_t *node) { switch (node->status) { case rf_wait: return ("wait"); case rf_fired: return ("fired"); case rf_good: return ("good"); case rf_bad: return ("bad"); default: return ("?"); } } void rf_PrintNodeInfoString(RF_DagNode_t *node) { RF_PhysDiskAddr_t *pda; int (*df) (RF_DagNode_t *) = node->doFunc; int i, lk, unlk; void *bufPtr; if ((df == rf_DiskReadFunc) || (df == rf_DiskWriteFunc) || (df == rf_DiskReadMirrorIdleFunc) || (df == rf_DiskReadMirrorPartitionFunc)) { pda = (RF_PhysDiskAddr_t *) node->params[0].p; bufPtr = (void *) node->params[1].p; lk = 0; unlk = 0; RF_ASSERT(!(lk && unlk)); printf("c %d offs %ld nsect %d buf 0x%lx %s\n", pda->col, (long) pda->startSector, (int) pda->numSector, (long) bufPtr, (lk) ? "LOCK" : ((unlk) ? "UNLK" : " ")); return; } if ((df == rf_SimpleXorFunc) || (df == rf_RegularXorFunc) || (df == rf_RecoveryXorFunc)) { printf("result buf 0x%lx\n", (long) node->results[0]); for (i = 0; i < node->numParams - 1; i += 2) { pda = (RF_PhysDiskAddr_t *) node->params[i].p; bufPtr = (RF_PhysDiskAddr_t *) node->params[i + 1].p; printf(" buf 0x%lx c%d offs %ld nsect %d\n", (long) bufPtr, pda->col, (long) pda->startSector, (int) pda->numSector); } return; } #if RF_INCLUDE_PARITYLOGGING > 0 if (df == rf_ParityLogOverwriteFunc || df == rf_ParityLogUpdateFunc) { for (i = 0; i < node->numParams - 1; i += 2) { pda = (RF_PhysDiskAddr_t *) node->params[i].p; bufPtr = (RF_PhysDiskAddr_t *) node->params[i + 1].p; printf(" c%d offs %ld nsect %d buf 0x%lx\n", pda->col, (long) pda->startSector, (int) pda->numSector, (long) bufPtr); } return; } #endif /* RF_INCLUDE_PARITYLOGGING > 0 */ if ((df == rf_TerminateFunc) || (df == rf_NullNodeFunc)) { printf("\n"); return; } printf("?\n"); } #ifdef DEBUG static void rf_RecurPrintDAG(RF_DagNode_t *node, int depth, int unvisited) { char *anttype; int i; node->visited = (unvisited) ? 0 : 1; printf("(%d) %d C%d %s: %s,s%d %d/%d,a%d/%d,p%d,r%d S{", depth, node->nodeNum, node->commitNode, node->name, rf_NodeStatusString(node), node->numSuccedents, node->numSuccFired, node->numSuccDone, node->numAntecedents, node->numAntDone, node->numParams, node->numResults); for (i = 0; i < node->numSuccedents; i++) { printf("%d%s", node->succedents[i]->nodeNum, ((i == node->numSuccedents - 1) ? "\0" : " ")); } printf("} A{"); for (i = 0; i < node->numAntecedents; i++) { switch (node->antType[i]) { case rf_trueData: anttype = "T"; break; case rf_antiData: anttype = "A"; break; case rf_outputData: anttype = "O"; break; case rf_control: anttype = "C"; break; default: anttype = "?"; break; } printf("%d(%s)%s", node->antecedents[i]->nodeNum, anttype, (i == node->numAntecedents - 1) ? "\0" : " "); } printf("}; "); rf_PrintNodeInfoString(node); for (i = 0; i < node->numSuccedents; i++) { if (node->succedents[i]->visited == unvisited) rf_RecurPrintDAG(node->succedents[i], depth + 1, unvisited); } } static void rf_PrintDAG(RF_DagHeader_t *dag_h) { int unvisited, i; char *status; /* set dag status */ switch (dag_h->status) { case rf_enable: status = "enable"; break; case rf_rollForward: status = "rollForward"; break; case rf_rollBackward: status = "rollBackward"; break; default: status = "illegal!"; break; } /* find out if visited bits are currently set or clear */ unvisited = dag_h->succedents[0]->visited; printf("DAG type: %s\n", dag_h->creator); printf("format is (depth) num commit type: status,nSucc nSuccFired/nSuccDone,nAnte/nAnteDone,nParam,nResult S{x} A{x(type)}; info\n"); printf("(0) %d Hdr: %s, s%d, (commit %d/%d) S{", dag_h->nodeNum, status, dag_h->numSuccedents, dag_h->numCommitNodes, dag_h->numCommits); for (i = 0; i < dag_h->numSuccedents; i++) { printf("%d%s", dag_h->succedents[i]->nodeNum, ((i == dag_h->numSuccedents - 1) ? "\0" : " ")); } printf("};\n"); for (i = 0; i < dag_h->numSuccedents; i++) { if (dag_h->succedents[i]->visited == unvisited) rf_RecurPrintDAG(dag_h->succedents[i], 1, unvisited); } } #endif /* assigns node numbers */ int rf_AssignNodeNums(RF_DagHeader_t * dag_h) { int unvisited, i, nnum; RF_DagNode_t *node; nnum = 0; unvisited = dag_h->succedents[0]->visited; dag_h->nodeNum = nnum++; for (i = 0; i < dag_h->numSuccedents; i++) { node = dag_h->succedents[i]; if (node->visited == unvisited) { nnum = rf_RecurAssignNodeNums(dag_h->succedents[i], nnum, unvisited); } } return (nnum); } int rf_RecurAssignNodeNums(RF_DagNode_t *node, int num, int unvisited) { int i; node->visited = (unvisited) ? 0 : 1; node->nodeNum = num++; for (i = 0; i < node->numSuccedents; i++) { if (node->succedents[i]->visited == unvisited) { num = rf_RecurAssignNodeNums(node->succedents[i], num, unvisited); } } return (num); } /* set the header pointers in each node to "newptr" */ void rf_ResetDAGHeaderPointers(RF_DagHeader_t *dag_h, RF_DagHeader_t *newptr) { int i; for (i = 0; i < dag_h->numSuccedents; i++) if (dag_h->succedents[i]->dagHdr != newptr) rf_RecurResetDAGHeaderPointers(dag_h->succedents[i], newptr); } void rf_RecurResetDAGHeaderPointers(RF_DagNode_t *node, RF_DagHeader_t *newptr) { int i; node->dagHdr = newptr; for (i = 0; i < node->numSuccedents; i++) if (node->succedents[i]->dagHdr != newptr) rf_RecurResetDAGHeaderPointers(node->succedents[i], newptr); } void rf_PrintDAGList(RF_DagHeader_t * dag_h) { int i = 0; for (; dag_h; dag_h = dag_h->next) { rf_AssignNodeNums(dag_h); printf("\n\nDAG %d IN LIST:\n", i++); rf_PrintDAG(dag_h); } } static int rf_ValidateBranch(RF_DagNode_t *node, int *scount, int *acount, RF_DagNode_t **nodes, int unvisited) { int i, retcode = 0; /* construct an array of node pointers indexed by node num */ node->visited = (unvisited) ? 0 : 1; nodes[node->nodeNum] = node; if (node->next != NULL) { printf("INVALID DAG: next pointer in node is not NULL\n"); retcode = 1; } if (node->status != rf_wait) { printf("INVALID DAG: Node status is not wait\n"); retcode = 1; } if (node->numAntDone != 0) { printf("INVALID DAG: numAntDone is not zero\n"); retcode = 1; } if (node->doFunc == rf_TerminateFunc) { if (node->numSuccedents != 0) { printf("INVALID DAG: Terminator node has succedents\n"); retcode = 1; } } else { if (node->numSuccedents == 0) { printf("INVALID DAG: Non-terminator node has no succedents\n"); retcode = 1; } } for (i = 0; i < node->numSuccedents; i++) { if (!node->succedents[i]) { printf("INVALID DAG: succedent %d of node %s is NULL\n", i, node->name); retcode = 1; } scount[node->succedents[i]->nodeNum]++; } for (i = 0; i < node->numAntecedents; i++) { if (!node->antecedents[i]) { printf("INVALID DAG: antecedent %d of node %s is NULL\n", i, node->name); retcode = 1; } acount[node->antecedents[i]->nodeNum]++; } for (i = 0; i < node->numSuccedents; i++) { if (node->succedents[i]->visited == unvisited) { if (rf_ValidateBranch(node->succedents[i], scount, acount, nodes, unvisited)) { retcode = 1; } } } return (retcode); } static void rf_ValidateBranchVisitedBits(RF_DagNode_t *node, int unvisited, int rl) { int i; RF_ASSERT(node->visited == unvisited); for (i = 0; i < node->numSuccedents; i++) { if (node->succedents[i] == NULL) { printf("node=%lx node->succedents[%d] is NULL\n", (long) node, i); RF_ASSERT(0); } rf_ValidateBranchVisitedBits(node->succedents[i], unvisited, rl + 1); } } /* NOTE: never call this on a big dag, because it is exponential * in execution time */ static void rf_ValidateVisitedBits(RF_DagHeader_t *dag) { int i, unvisited; unvisited = dag->succedents[0]->visited; for (i = 0; i < dag->numSuccedents; i++) { if (dag->succedents[i] == NULL) { printf("dag=%lx dag->succedents[%d] is NULL\n", (long) dag, i); RF_ASSERT(0); } rf_ValidateBranchVisitedBits(dag->succedents[i], unvisited, 0); } } /* validate a DAG. _at entry_ verify that: * -- numNodesCompleted is zero * -- node queue is null * -- dag status is rf_enable * -- next pointer is null on every node * -- all nodes have status wait * -- numAntDone is zero in all nodes * -- terminator node has zero successors * -- no other node besides terminator has zero successors * -- no successor or antecedent pointer in a node is NULL * -- number of times that each node appears as a successor of another node * is equal to the antecedent count on that node * -- number of times that each node appears as an antecedent of another node * is equal to the succedent count on that node * -- what else? */ int rf_ValidateDAG(RF_DagHeader_t *dag_h) { int i, nodecount; int *scount, *acount;/* per-node successor and antecedent counts */ RF_DagNode_t **nodes; /* array of ptrs to nodes in dag */ int retcode = 0; int unvisited; int commitNodeCount = 0; if (rf_validateVisitedDebug) rf_ValidateVisitedBits(dag_h); if (dag_h->numNodesCompleted != 0) { printf("INVALID DAG: num nodes completed is %d, should be 0\n", dag_h->numNodesCompleted); retcode = 1; goto validate_dag_bad; } if (dag_h->status != rf_enable) { printf("INVALID DAG: not enabled\n"); retcode = 1; goto validate_dag_bad; } if (dag_h->numCommits != 0) { printf("INVALID DAG: numCommits != 0 (%d)\n", dag_h->numCommits); retcode = 1; goto validate_dag_bad; } if (dag_h->numSuccedents != 1) { /* currently, all dags must have only one succedent */ printf("INVALID DAG: numSuccedents !1 (%d)\n", dag_h->numSuccedents); retcode = 1; goto validate_dag_bad; } nodecount = rf_AssignNodeNums(dag_h); unvisited = dag_h->succedents[0]->visited; scount = RF_Malloc(nodecount * sizeof(*scount)); acount = RF_Malloc(nodecount * sizeof(*acount)); nodes = RF_Malloc(nodecount * sizeof(*nodes)); for (i = 0; i < dag_h->numSuccedents; i++) { if ((dag_h->succedents[i]->visited == unvisited) && rf_ValidateBranch(dag_h->succedents[i], scount, acount, nodes, unvisited)) { retcode = 1; } } /* start at 1 to skip the header node */ for (i = 1; i < nodecount; i++) { if (nodes[i]->commitNode) commitNodeCount++; if (nodes[i]->doFunc == NULL) { printf("INVALID DAG: node %s has an undefined doFunc\n", nodes[i]->name); retcode = 1; goto validate_dag_out; } if (nodes[i]->undoFunc == NULL) { printf("INVALID DAG: node %s has an undefined doFunc\n", nodes[i]->name); retcode = 1; goto validate_dag_out; } if (nodes[i]->numAntecedents != scount[nodes[i]->nodeNum]) { printf("INVALID DAG: node %s has %d antecedents but appears as a succedent %d times\n", nodes[i]->name, nodes[i]->numAntecedents, scount[nodes[i]->nodeNum]); retcode = 1; goto validate_dag_out; } if (nodes[i]->numSuccedents != acount[nodes[i]->nodeNum]) { printf("INVALID DAG: node %s has %d succedents but appears as an antecedent %d times\n", nodes[i]->name, nodes[i]->numSuccedents, acount[nodes[i]->nodeNum]); retcode = 1; goto validate_dag_out; } } if (dag_h->numCommitNodes != commitNodeCount) { printf("INVALID DAG: incorrect commit node count. hdr->numCommitNodes (%d) found (%d) commit nodes in graph\n", dag_h->numCommitNodes, commitNodeCount); retcode = 1; goto validate_dag_out; } validate_dag_out: RF_Free(scount, nodecount * sizeof(int)); RF_Free(acount, nodecount * sizeof(int)); RF_Free(nodes, nodecount * sizeof(RF_DagNode_t *)); if (retcode) rf_PrintDAGList(dag_h); if (rf_validateVisitedDebug) rf_ValidateVisitedBits(dag_h); return (retcode); validate_dag_bad: rf_PrintDAGList(dag_h); return (retcode); } #endif /* RF_DEBUG_VALIDATE_DAG */ /****************************************************************************** * * misc construction routines * *****************************************************************************/ void rf_redirect_asm(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asmap) { int ds = (raidPtr->Layout.map->flags & RF_DISTRIBUTE_SPARE) ? 1 : 0; int fcol = raidPtr->reconControl->fcol; int scol = raidPtr->reconControl->spareCol; RF_PhysDiskAddr_t *pda; RF_ASSERT(raidPtr->status == rf_rs_reconstructing); for (pda = asmap->physInfo; pda; pda = pda->next) { if (pda->col == fcol) { #if RF_DEBUG_DAG if (rf_dagDebug) { if (!rf_CheckRUReconstructed(raidPtr->reconControl->reconMap, pda->startSector)) { RF_PANIC(); } } #endif /* printf("Remapped data for large write\n"); */ if (ds) { raidPtr->Layout.map->MapSector(raidPtr, pda->raidAddress, &pda->col, &pda->startSector, RF_REMAP); } else { pda->col = scol; } } } for (pda = asmap->parityInfo; pda; pda = pda->next) { if (pda->col == fcol) { #if RF_DEBUG_DAG if (rf_dagDebug) { if (!rf_CheckRUReconstructed(raidPtr->reconControl->reconMap, pda->startSector)) { RF_PANIC(); } } #endif } if (ds) { (raidPtr->Layout.map->MapParity) (raidPtr, pda->raidAddress, &pda->col, &pda->startSector, RF_REMAP); } else { pda->col = scol; } } } /* this routine allocates read buffers and generates stripe maps for the * regions of the array from the start of the stripe to the start of the * access, and from the end of the access to the end of the stripe. It also * computes and returns the number of DAG nodes needed to read all this data. * Note that this routine does the wrong thing if the access is fully * contained within one stripe unit, so we RF_ASSERT against this case at the * start. * * layoutPtr - in: layout information * asmap - in: access stripe map * dag_h - in: header of the dag to create * new_asm_h - in: ptr to array of 2 headers. to be filled in * nRodNodes - out: num nodes to be generated to read unaccessed data * sosBuffer, eosBuffer - out: pointers to newly allocated buffer */ void rf_MapUnaccessedPortionOfStripe(RF_Raid_t *raidPtr, RF_RaidLayout_t *layoutPtr, RF_AccessStripeMap_t *asmap, RF_DagHeader_t *dag_h, RF_AccessStripeMapHeader_t **new_asm_h, int *nRodNodes, char **sosBuffer, char **eosBuffer, RF_AllocListElem_t *allocList) { RF_RaidAddr_t sosRaidAddress, eosRaidAddress; RF_SectorNum_t sosNumSector, eosNumSector; RF_ASSERT(asmap->numStripeUnitsAccessed > (layoutPtr->numDataCol / 2)); /* generate an access map for the region of the array from start of * stripe to start of access */ new_asm_h[0] = new_asm_h[1] = NULL; *nRodNodes = 0; if (!rf_RaidAddressStripeAligned(layoutPtr, asmap->raidAddress)) { sosRaidAddress = rf_RaidAddressOfPrevStripeBoundary(layoutPtr, asmap->raidAddress); sosNumSector = asmap->raidAddress - sosRaidAddress; *sosBuffer = rf_AllocStripeBuffer(raidPtr, dag_h, rf_RaidAddressToByte(raidPtr, sosNumSector)); new_asm_h[0] = rf_MapAccess(raidPtr, sosRaidAddress, sosNumSector, *sosBuffer, RF_DONT_REMAP); new_asm_h[0]->next = dag_h->asmList; dag_h->asmList = new_asm_h[0]; *nRodNodes += new_asm_h[0]->stripeMap->numStripeUnitsAccessed; RF_ASSERT(new_asm_h[0]->stripeMap->next == NULL); /* we're totally within one stripe here */ if (asmap->flags & RF_ASM_REDIR_LARGE_WRITE) rf_redirect_asm(raidPtr, new_asm_h[0]->stripeMap); } /* generate an access map for the region of the array from end of * access to end of stripe */ if (!rf_RaidAddressStripeAligned(layoutPtr, asmap->endRaidAddress)) { eosRaidAddress = asmap->endRaidAddress; eosNumSector = rf_RaidAddressOfNextStripeBoundary(layoutPtr, eosRaidAddress) - eosRaidAddress; *eosBuffer = rf_AllocStripeBuffer(raidPtr, dag_h, rf_RaidAddressToByte(raidPtr, eosNumSector)); new_asm_h[1] = rf_MapAccess(raidPtr, eosRaidAddress, eosNumSector, *eosBuffer, RF_DONT_REMAP); new_asm_h[1]->next = dag_h->asmList; dag_h->asmList = new_asm_h[1]; *nRodNodes += new_asm_h[1]->stripeMap->numStripeUnitsAccessed; RF_ASSERT(new_asm_h[1]->stripeMap->next == NULL); /* we're totally within one stripe here */ if (asmap->flags & RF_ASM_REDIR_LARGE_WRITE) rf_redirect_asm(raidPtr, new_asm_h[1]->stripeMap); } } /* returns non-zero if the indicated ranges of stripe unit offsets overlap */ int rf_PDAOverlap(RF_RaidLayout_t *layoutPtr, RF_PhysDiskAddr_t *src, RF_PhysDiskAddr_t *dest) { RF_SectorNum_t soffs = rf_StripeUnitOffset(layoutPtr, src->startSector); RF_SectorNum_t doffs = rf_StripeUnitOffset(layoutPtr, dest->startSector); /* use -1 to be sure we stay within SU */ RF_SectorNum_t send = rf_StripeUnitOffset(layoutPtr, src->startSector + src->numSector - 1); RF_SectorNum_t dend = rf_StripeUnitOffset(layoutPtr, dest->startSector + dest->numSector - 1); return ((RF_MAX(soffs, doffs) <= RF_MIN(send, dend)) ? 1 : 0); } /* GenerateFailedAccessASMs * * this routine figures out what portion of the stripe needs to be read * to effect the degraded read or write operation. It's primary function * is to identify everything required to recover the data, and then * eliminate anything that is already being accessed by the user. * * The main result is two new ASMs, one for the region from the start of the * stripe to the start of the access, and one for the region from the end of * the access to the end of the stripe. These ASMs describe everything that * needs to be read to effect the degraded access. Other results are: * nXorBufs -- the total number of buffers that need to be XORed together to * recover the lost data, * rpBufPtr -- ptr to a newly-allocated buffer to hold the parity. If NULL * at entry, not allocated. * overlappingPDAs -- * describes which of the non-failed PDAs in the user access * overlap data that needs to be read to effect recovery. * overlappingPDAs[i]==1 if and only if, neglecting the failed * PDA, the ith pda in the input asm overlaps data that needs * to be read for recovery. */ /* in: asm - ASM for the actual access, one stripe only */ /* in: failedPDA - which component of the access has failed */ /* in: dag_h - header of the DAG we're going to create */ /* out: new_asm_h - the two new ASMs */ /* out: nXorBufs - the total number of xor bufs required */ /* out: rpBufPtr - a buffer for the parity read */ void rf_GenerateFailedAccessASMs(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *asmap, RF_PhysDiskAddr_t *failedPDA, RF_DagHeader_t *dag_h, RF_AccessStripeMapHeader_t **new_asm_h, int *nXorBufs, char **rpBufPtr, char *overlappingPDAs, RF_AllocListElem_t *allocList) { RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout); /* s=start, e=end, s=stripe, a=access, f=failed, su=stripe unit */ RF_RaidAddr_t sosAddr, sosEndAddr, eosStartAddr, eosAddr; RF_PhysDiskAddr_t *pda; int foundit, i; foundit = 0; /* first compute the following raid addresses: start of stripe, * (sosAddr) MIN(start of access, start of failed SU), (sosEndAddr) * MAX(end of access, end of failed SU), (eosStartAddr) end of * stripe (i.e. start of next stripe) (eosAddr) */ sosAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr, asmap->raidAddress); sosEndAddr = RF_MIN(asmap->raidAddress, rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, failedPDA->raidAddress)); eosStartAddr = RF_MAX(asmap->endRaidAddress, rf_RaidAddressOfNextStripeUnitBoundary(layoutPtr, failedPDA->raidAddress)); eosAddr = rf_RaidAddressOfNextStripeBoundary(layoutPtr, asmap->raidAddress); /* now generate access stripe maps for each of the above regions of * the stripe. Use a dummy (NULL) buf ptr for now */ new_asm_h[0] = (sosAddr != sosEndAddr) ? rf_MapAccess(raidPtr, sosAddr, sosEndAddr - sosAddr, NULL, RF_DONT_REMAP) : NULL; new_asm_h[1] = (eosStartAddr != eosAddr) ? rf_MapAccess(raidPtr, eosStartAddr, eosAddr - eosStartAddr, NULL, RF_DONT_REMAP) : NULL; /* walk through the PDAs and range-restrict each SU to the region of * the SU touched on the failed PDA. also compute total data buffer * space requirements in this step. Ignore the parity for now. */ /* Also count nodes to find out how many bufs need to be xored together */ (*nXorBufs) = 1; /* in read case, 1 is for parity. In write * case, 1 is for failed data */ if (new_asm_h[0]) { new_asm_h[0]->next = dag_h->asmList; dag_h->asmList = new_asm_h[0]; for (pda = new_asm_h[0]->stripeMap->physInfo; pda; pda = pda->next) { rf_RangeRestrictPDA(raidPtr, failedPDA, pda, RF_RESTRICT_NOBUFFER, 0); pda->bufPtr = rf_AllocBuffer(raidPtr, dag_h, pda->numSector << raidPtr->logBytesPerSector); } (*nXorBufs) += new_asm_h[0]->stripeMap->numStripeUnitsAccessed; } if (new_asm_h[1]) { new_asm_h[1]->next = dag_h->asmList; dag_h->asmList = new_asm_h[1]; for (pda = new_asm_h[1]->stripeMap->physInfo; pda; pda = pda->next) { rf_RangeRestrictPDA(raidPtr, failedPDA, pda, RF_RESTRICT_NOBUFFER, 0); pda->bufPtr = rf_AllocBuffer(raidPtr, dag_h, pda->numSector << raidPtr->logBytesPerSector); } (*nXorBufs) += new_asm_h[1]->stripeMap->numStripeUnitsAccessed; } /* allocate a buffer for parity */ if (rpBufPtr) *rpBufPtr = rf_AllocBuffer(raidPtr, dag_h, failedPDA->numSector << raidPtr->logBytesPerSector); /* the last step is to figure out how many more distinct buffers need * to get xor'd to produce the missing unit. there's one for each * user-data read node that overlaps the portion of the failed unit * being accessed */ for (foundit = i = 0, pda = asmap->physInfo; pda; i++, pda = pda->next) { if (pda == failedPDA) { i--; foundit = 1; continue; } if (rf_PDAOverlap(layoutPtr, pda, failedPDA)) { overlappingPDAs[i] = 1; (*nXorBufs)++; } } if (!foundit) { RF_ERRORMSG("GenerateFailedAccessASMs: did not find failedPDA in asm list\n"); RF_ASSERT(0); } #if RF_DEBUG_DAG if (rf_degDagDebug) { if (new_asm_h[0]) { printf("First asm:\n"); rf_PrintFullAccessStripeMap(new_asm_h[0], 1); } if (new_asm_h[1]) { printf("Second asm:\n"); rf_PrintFullAccessStripeMap(new_asm_h[1], 1); } } #endif } /* adjusts the offset and number of sectors in the destination pda so that * it covers at most the region of the SU covered by the source PDA. This * is exclusively a restriction: the number of sectors indicated by the * target PDA can only shrink. * * For example: s = sectors within SU indicated by source PDA * d = sectors within SU indicated by dest PDA * r = results, stored in dest PDA * * |--------------- one stripe unit ---------------------| * | sssssssssssssssssssssssssssssssss | * | ddddddddddddddddddddddddddddddddddddddddddddd | * | rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr | * * Another example: * * |--------------- one stripe unit ---------------------| * | sssssssssssssssssssssssssssssssss | * | ddddddddddddddddddddddd | * | rrrrrrrrrrrrrrrr | * */ void rf_RangeRestrictPDA(RF_Raid_t *raidPtr, RF_PhysDiskAddr_t *src, RF_PhysDiskAddr_t *dest, int dobuffer, int doraidaddr) { RF_RaidLayout_t *layoutPtr = &raidPtr->Layout; RF_SectorNum_t soffs = rf_StripeUnitOffset(layoutPtr, src->startSector); RF_SectorNum_t doffs = rf_StripeUnitOffset(layoutPtr, dest->startSector); RF_SectorNum_t send = rf_StripeUnitOffset(layoutPtr, src->startSector + src->numSector - 1); /* use -1 to be sure we * stay within SU */ RF_SectorNum_t dend = rf_StripeUnitOffset(layoutPtr, dest->startSector + dest->numSector - 1); RF_SectorNum_t subAddr = rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, dest->startSector); /* stripe unit boundary */ dest->startSector = subAddr + RF_MAX(soffs, doffs); dest->numSector = subAddr + RF_MIN(send, dend) + 1 - dest->startSector; if (dobuffer) dest->bufPtr = (char *)(dest->bufPtr) + ((soffs > doffs) ? rf_RaidAddressToByte(raidPtr, soffs - doffs) : 0); if (doraidaddr) { dest->raidAddress = rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, dest->raidAddress) + rf_StripeUnitOffset(layoutPtr, dest->startSector); } } #if (RF_INCLUDE_CHAINDECLUSTER > 0) /* * Want the highest of these primes to be the largest one * less than the max expected number of columns (won't hurt * to be too small or too large, but won't be optimal, either) * --jimz */ #define NLOWPRIMES 8 static int lowprimes[NLOWPRIMES] = {2, 3, 5, 7, 11, 13, 17, 19}; /***************************************************************************** * compute the workload shift factor. (chained declustering) * * return nonzero if access should shift to secondary, otherwise, * access is to primary *****************************************************************************/ int rf_compute_workload_shift(RF_Raid_t *raidPtr, RF_PhysDiskAddr_t *pda) { /* * variables: * d = column of disk containing primary * f = column of failed disk * n = number of disks in array * sd = "shift distance" (number of columns that d is to the right of f) * v = numerator of redirection ratio * k = denominator of redirection ratio */ RF_RowCol_t d, f, sd, n; int k, v, ret, i; n = raidPtr->numCol; /* assign column of primary copy to d */ d = pda->col; /* assign column of dead disk to f */ for (f = 0; ((!RF_DEAD_DISK(raidPtr->Disks[f].status)) && (f < n)); f++) continue; RF_ASSERT(f < n); RF_ASSERT(f != d); sd = (f > d) ? (n + d - f) : (d - f); RF_ASSERT(sd < n); /* * v of every k accesses should be redirected * * v/k := (n-1-sd)/(n-1) */ v = (n - 1 - sd); k = (n - 1); #if 1 /* * XXX * Is this worth it? * * Now reduce the fraction, by repeatedly factoring * out primes (just like they teach in elementary school!) */ for (i = 0; i < NLOWPRIMES; i++) { if (lowprimes[i] > v) break; while (((v % lowprimes[i]) == 0) && ((k % lowprimes[i]) == 0)) { v /= lowprimes[i]; k /= lowprimes[i]; } } #endif raidPtr->hist_diskreq[d]++; if (raidPtr->hist_diskreq[d] > v) { ret = 0; /* do not redirect */ } else { ret = 1; /* redirect */ } #if 0 printf("d=%d f=%d sd=%d v=%d k=%d ret=%d h=%d\n", d, f, sd, v, k, ret, raidPtr->hist_diskreq[d]); #endif if (raidPtr->hist_diskreq[d] >= k) { /* reset counter */ raidPtr->hist_diskreq[d] = 0; } return (ret); } #endif /* (RF_INCLUDE_CHAINDECLUSTER > 0) */ /* * Disk selection routines */ /* * Selects the disk with the shortest queue from a mirror pair. * Both the disk I/Os queued in RAIDframe as well as those at the physical * disk are counted as members of the "queue" */ void rf_SelectMirrorDiskIdle(RF_DagNode_t * node) { RF_Raid_t *raidPtr = (RF_Raid_t *) node->dagHdr->raidPtr; RF_RowCol_t colData, colMirror; int dataQueueLength, mirrorQueueLength, usemirror; RF_PhysDiskAddr_t *data_pda = (RF_PhysDiskAddr_t *) node->params[0].p; RF_PhysDiskAddr_t *mirror_pda = (RF_PhysDiskAddr_t *) node->params[4].p; RF_PhysDiskAddr_t *tmp_pda; RF_RaidDisk_t *disks = raidPtr->Disks; RF_DiskQueue_t *dqs = raidPtr->Queues, *dataQueue, *mirrorQueue; /* return the [row col] of the disk with the shortest queue */ colData = data_pda->col; colMirror = mirror_pda->col; dataQueue = &(dqs[colData]); mirrorQueue = &(dqs[colMirror]); #ifdef RF_LOCK_QUEUES_TO_READ_LEN RF_LOCK_QUEUE_MUTEX(dataQueue, "SelectMirrorDiskIdle"); #endif /* RF_LOCK_QUEUES_TO_READ_LEN */ dataQueueLength = dataQueue->queueLength + dataQueue->numOutstanding; #ifdef RF_LOCK_QUEUES_TO_READ_LEN RF_UNLOCK_QUEUE_MUTEX(dataQueue, "SelectMirrorDiskIdle"); RF_LOCK_QUEUE_MUTEX(mirrorQueue, "SelectMirrorDiskIdle"); #endif /* RF_LOCK_QUEUES_TO_READ_LEN */ mirrorQueueLength = mirrorQueue->queueLength + mirrorQueue->numOutstanding; #ifdef RF_LOCK_QUEUES_TO_READ_LEN RF_UNLOCK_QUEUE_MUTEX(mirrorQueue, "SelectMirrorDiskIdle"); #endif /* RF_LOCK_QUEUES_TO_READ_LEN */ usemirror = 0; if (RF_DEAD_DISK(disks[colMirror].status)) { usemirror = 0; } else if (RF_DEAD_DISK(disks[colData].status)) { usemirror = 1; } else if (raidPtr->parity_good == RF_RAID_DIRTY) { /* Trust only the main disk */ usemirror = 0; } else if (dataQueueLength < mirrorQueueLength) { usemirror = 0; } else if (mirrorQueueLength < dataQueueLength) { usemirror = 1; } else { /* queues are equal length. attempt * cleverness. */ if (SNUM_DIFF(dataQueue->last_deq_sector, data_pda->startSector) <= SNUM_DIFF(mirrorQueue->last_deq_sector, mirror_pda->startSector)) { usemirror = 0; } else { usemirror = 1; } } if (usemirror) { /* use mirror (parity) disk, swap params 0 & 4 */ tmp_pda = data_pda; node->params[0].p = mirror_pda; node->params[4].p = tmp_pda; } else { /* use data disk, leave param 0 unchanged */ } /* printf("dataQueueLength %d, mirrorQueueLength * %d\n",dataQueueLength, mirrorQueueLength); */ } #if (RF_INCLUDE_CHAINDECLUSTER > 0) || (RF_INCLUDE_INTERDECLUSTER > 0) || (RF_DEBUG_VALIDATE_DAG > 0) /* * Do simple partitioning. This assumes that * the data and parity disks are laid out identically. */ void rf_SelectMirrorDiskPartition(RF_DagNode_t * node) { RF_Raid_t *raidPtr = (RF_Raid_t *) node->dagHdr->raidPtr; RF_RowCol_t colData, colMirror; RF_PhysDiskAddr_t *data_pda = (RF_PhysDiskAddr_t *) node->params[0].p; RF_PhysDiskAddr_t *mirror_pda = (RF_PhysDiskAddr_t *) node->params[4].p; RF_PhysDiskAddr_t *tmp_pda; RF_RaidDisk_t *disks = raidPtr->Disks; int usemirror; /* return the [row col] of the disk with the shortest queue */ colData = data_pda->col; colMirror = mirror_pda->col; usemirror = 0; if (RF_DEAD_DISK(disks[colMirror].status)) { usemirror = 0; } else if (RF_DEAD_DISK(disks[colData].status)) { usemirror = 1; } else if (raidPtr->parity_good == RF_RAID_DIRTY) { /* Trust only the main disk */ usemirror = 0; } else if (data_pda->startSector < (disks[colData].numBlocks / 2)) { usemirror = 0; } else { usemirror = 1; } if (usemirror) { /* use mirror (parity) disk, swap params 0 & 4 */ tmp_pda = data_pda; node->params[0].p = mirror_pda; node->params[4].p = tmp_pda; } else { /* use data disk, leave param 0 unchanged */ } } #endif