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rf_states.c revision 1.44
      1 /*	$NetBSD: rf_states.c,v 1.44 2009/11/17 18:54:26 jld Exp $	*/
      2 /*
      3  * Copyright (c) 1995 Carnegie-Mellon University.
      4  * All rights reserved.
      5  *
      6  * Author: Mark Holland, William V. Courtright II, Robby Findler
      7  *
      8  * Permission to use, copy, modify and distribute this software and
      9  * its documentation is hereby granted, provided that both the copyright
     10  * notice and this permission notice appear in all copies of the
     11  * software, derivative works or modified versions, and any portions
     12  * thereof, and that both notices appear in supporting documentation.
     13  *
     14  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     15  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
     16  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     17  *
     18  * Carnegie Mellon requests users of this software to return to
     19  *
     20  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     21  *  School of Computer Science
     22  *  Carnegie Mellon University
     23  *  Pittsburgh PA 15213-3890
     24  *
     25  * any improvements or extensions that they make and grant Carnegie the
     26  * rights to redistribute these changes.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __KERNEL_RCSID(0, "$NetBSD: rf_states.c,v 1.44 2009/11/17 18:54:26 jld Exp $");
     31 
     32 #include <sys/errno.h>
     33 
     34 #include "rf_archs.h"
     35 #include "rf_threadstuff.h"
     36 #include "rf_raid.h"
     37 #include "rf_dag.h"
     38 #include "rf_desc.h"
     39 #include "rf_aselect.h"
     40 #include "rf_general.h"
     41 #include "rf_states.h"
     42 #include "rf_dagutils.h"
     43 #include "rf_driver.h"
     44 #include "rf_engine.h"
     45 #include "rf_map.h"
     46 #include "rf_etimer.h"
     47 #include "rf_kintf.h"
     48 #include "rf_paritymap.h"
     49 
     50 #ifndef RF_DEBUG_STATES
     51 #define RF_DEBUG_STATES 0
     52 #endif
     53 
     54 /* prototypes for some of the available states.
     55 
     56    States must:
     57 
     58      - not block.
     59 
     60      - either schedule rf_ContinueRaidAccess as a callback and return
     61        RF_TRUE, or complete all of their work and return RF_FALSE.
     62 
     63      - increment desc->state when they have finished their work.
     64 */
     65 
     66 #if RF_DEBUG_STATES
     67 static char *
     68 StateName(RF_AccessState_t state)
     69 {
     70 	switch (state) {
     71 		case rf_QuiesceState:return "QuiesceState";
     72 	case rf_MapState:
     73 		return "MapState";
     74 	case rf_LockState:
     75 		return "LockState";
     76 	case rf_CreateDAGState:
     77 		return "CreateDAGState";
     78 	case rf_ExecuteDAGState:
     79 		return "ExecuteDAGState";
     80 	case rf_ProcessDAGState:
     81 		return "ProcessDAGState";
     82 	case rf_CleanupState:
     83 		return "CleanupState";
     84 	case rf_LastState:
     85 		return "LastState";
     86 	case rf_IncrAccessesCountState:
     87 		return "IncrAccessesCountState";
     88 	case rf_DecrAccessesCountState:
     89 		return "DecrAccessesCountState";
     90 	default:
     91 		return "!!! UnnamedState !!!";
     92 	}
     93 }
     94 #endif
     95 
     96 void
     97 rf_ContinueRaidAccess(RF_RaidAccessDesc_t *desc)
     98 {
     99 	int     suspended = RF_FALSE;
    100 	int     current_state_index = desc->state;
    101 	RF_AccessState_t current_state = desc->states[current_state_index];
    102 #if RF_DEBUG_STATES
    103 	int     unit = desc->raidPtr->raidid;
    104 #endif
    105 
    106 	do {
    107 
    108 		current_state_index = desc->state;
    109 		current_state = desc->states[current_state_index];
    110 
    111 		switch (current_state) {
    112 
    113 		case rf_QuiesceState:
    114 			suspended = rf_State_Quiesce(desc);
    115 			break;
    116 		case rf_IncrAccessesCountState:
    117 			suspended = rf_State_IncrAccessCount(desc);
    118 			break;
    119 		case rf_MapState:
    120 			suspended = rf_State_Map(desc);
    121 			break;
    122 		case rf_LockState:
    123 			suspended = rf_State_Lock(desc);
    124 			break;
    125 		case rf_CreateDAGState:
    126 			suspended = rf_State_CreateDAG(desc);
    127 			break;
    128 		case rf_ExecuteDAGState:
    129 			suspended = rf_State_ExecuteDAG(desc);
    130 			break;
    131 		case rf_ProcessDAGState:
    132 			suspended = rf_State_ProcessDAG(desc);
    133 			break;
    134 		case rf_CleanupState:
    135 			suspended = rf_State_Cleanup(desc);
    136 			break;
    137 		case rf_DecrAccessesCountState:
    138 			suspended = rf_State_DecrAccessCount(desc);
    139 			break;
    140 		case rf_LastState:
    141 			suspended = rf_State_LastState(desc);
    142 			break;
    143 		}
    144 
    145 		/* after this point, we cannot dereference desc since
    146 		 * desc may have been freed. desc is only freed in
    147 		 * LastState, so if we renter this function or loop
    148 		 * back up, desc should be valid. */
    149 
    150 #if RF_DEBUG_STATES
    151 		if (rf_printStatesDebug) {
    152 			printf("raid%d: State: %-24s StateIndex: %3i desc: 0x%ld %s\n",
    153 			       unit, StateName(current_state),
    154 			       current_state_index, (long) desc,
    155 			       suspended ? "callback scheduled" : "looping");
    156 		}
    157 #endif
    158 	} while (!suspended && current_state != rf_LastState);
    159 
    160 	return;
    161 }
    162 
    163 
    164 void
    165 rf_ContinueDagAccess(RF_DagList_t *dagList)
    166 {
    167 #if RF_ACC_TRACE > 0
    168 	RF_AccTraceEntry_t *tracerec = &(dagList->desc->tracerec);
    169 	RF_Etimer_t timer;
    170 #endif
    171 	RF_RaidAccessDesc_t *desc;
    172 	RF_DagHeader_t *dag_h;
    173 	int     i;
    174 
    175 	desc = dagList->desc;
    176 
    177 #if RF_ACC_TRACE > 0
    178 	timer = tracerec->timer;
    179 	RF_ETIMER_STOP(timer);
    180 	RF_ETIMER_EVAL(timer);
    181 	tracerec->specific.user.exec_us = RF_ETIMER_VAL_US(timer);
    182 	RF_ETIMER_START(tracerec->timer);
    183 #endif
    184 
    185 	/* skip to dag which just finished */
    186 	dag_h = dagList->dags;
    187 	for (i = 0; i < dagList->numDagsDone; i++) {
    188 		dag_h = dag_h->next;
    189 	}
    190 
    191 	/* check to see if retry is required */
    192 	if (dag_h->status == rf_rollBackward) {
    193 		/* when a dag fails, mark desc status as bad and allow
    194 		 * all other dags in the desc to execute to
    195 		 * completion.  then, free all dags and start over */
    196 		desc->status = 1;	/* bad status */
    197 #if 0
    198 		printf("raid%d: DAG failure: %c addr 0x%lx "
    199 		       "(%ld) nblk 0x%x (%d) buf 0x%lx state %d\n",
    200 		       desc->raidPtr->raidid, desc->type,
    201 		       (long) desc->raidAddress,
    202 		       (long) desc->raidAddress, (int) desc->numBlocks,
    203 		       (int) desc->numBlocks,
    204 		       (unsigned long) (desc->bufPtr), desc->state);
    205 #endif
    206 	}
    207 	dagList->numDagsDone++;
    208 	rf_ContinueRaidAccess(desc);
    209 }
    210 
    211 int
    212 rf_State_LastState(RF_RaidAccessDesc_t *desc)
    213 {
    214 	void    (*callbackFunc) (RF_CBParam_t) = desc->callbackFunc;
    215 	RF_CBParam_t callbackArg;
    216 
    217 	callbackArg.p = desc->callbackArg;
    218 
    219 	/*
    220 	 * If this is not an async request, wake up the caller
    221 	 */
    222 	if (desc->async_flag == 0)
    223 		wakeup(desc->bp);
    224 
    225 	/*
    226 	 * That's all the IO for this one... unbusy the 'disk'.
    227 	 */
    228 
    229 	rf_disk_unbusy(desc);
    230 
    231 	/*
    232 	 * Wakeup any requests waiting to go.
    233 	 */
    234 
    235 	RF_LOCK_MUTEX(((RF_Raid_t *) desc->raidPtr)->mutex);
    236 	((RF_Raid_t *) desc->raidPtr)->openings++;
    237 	RF_UNLOCK_MUTEX(((RF_Raid_t *) desc->raidPtr)->mutex);
    238 
    239 	wakeup(&(desc->raidPtr->iodone));
    240 
    241 	/*
    242 	 * The parity_map hook has to go here, because the iodone
    243 	 * callback goes straight into the kintf layer.
    244 	 */
    245 	if (desc->raidPtr->parity_map != NULL &&
    246 	    desc->type == RF_IO_TYPE_WRITE)
    247 		rf_paritymap_end(desc->raidPtr->parity_map,
    248 		    desc->raidAddress, desc->numBlocks);
    249 
    250 	/* printf("Calling biodone on 0x%x\n",desc->bp); */
    251 	biodone(desc->bp);	/* access came through ioctl */
    252 
    253 	if (callbackFunc)
    254 		callbackFunc(callbackArg);
    255 	rf_FreeRaidAccDesc(desc);
    256 
    257 	return RF_FALSE;
    258 }
    259 
    260 int
    261 rf_State_IncrAccessCount(RF_RaidAccessDesc_t *desc)
    262 {
    263 	RF_Raid_t *raidPtr;
    264 
    265 	raidPtr = desc->raidPtr;
    266 	/* Bummer. We have to do this to be 100% safe w.r.t. the increment
    267 	 * below */
    268 	RF_LOCK_MUTEX(raidPtr->access_suspend_mutex);
    269 	raidPtr->accs_in_flight++;	/* used to detect quiescence */
    270 	RF_UNLOCK_MUTEX(raidPtr->access_suspend_mutex);
    271 
    272 	desc->state++;
    273 	return RF_FALSE;
    274 }
    275 
    276 int
    277 rf_State_DecrAccessCount(RF_RaidAccessDesc_t *desc)
    278 {
    279 	RF_Raid_t *raidPtr;
    280 
    281 	raidPtr = desc->raidPtr;
    282 
    283 	RF_LOCK_MUTEX(raidPtr->access_suspend_mutex);
    284 	raidPtr->accs_in_flight--;
    285 	if (raidPtr->accesses_suspended && raidPtr->accs_in_flight == 0) {
    286 		rf_SignalQuiescenceLock(raidPtr);
    287 	}
    288 	RF_UNLOCK_MUTEX(raidPtr->access_suspend_mutex);
    289 
    290 	desc->state++;
    291 	return RF_FALSE;
    292 }
    293 
    294 int
    295 rf_State_Quiesce(RF_RaidAccessDesc_t *desc)
    296 {
    297 #if RF_ACC_TRACE > 0
    298 	RF_AccTraceEntry_t *tracerec = &desc->tracerec;
    299 	RF_Etimer_t timer;
    300 #endif
    301 	RF_CallbackDesc_t *cb;
    302 	RF_Raid_t *raidPtr;
    303 	int     suspended = RF_FALSE;
    304 	int need_cb, used_cb;
    305 
    306 	raidPtr = desc->raidPtr;
    307 
    308 #if RF_ACC_TRACE > 0
    309 	RF_ETIMER_START(timer);
    310 	RF_ETIMER_START(desc->timer);
    311 #endif
    312 
    313 	need_cb = 0;
    314 	used_cb = 0;
    315 	cb = NULL;
    316 
    317 	RF_LOCK_MUTEX(raidPtr->access_suspend_mutex);
    318 	/* Do an initial check to see if we might need a callback structure */
    319 	if (raidPtr->accesses_suspended) {
    320 		need_cb = 1;
    321 	}
    322 	RF_UNLOCK_MUTEX(raidPtr->access_suspend_mutex);
    323 
    324 	if (need_cb) {
    325 		/* create a callback if we might need it...
    326 		   and we likely do. */
    327 		cb = rf_AllocCallbackDesc();
    328 	}
    329 
    330 	RF_LOCK_MUTEX(raidPtr->access_suspend_mutex);
    331 	if (raidPtr->accesses_suspended) {
    332 		cb->callbackFunc = (void (*) (RF_CBParam_t)) rf_ContinueRaidAccess;
    333 		cb->callbackArg.p = (void *) desc;
    334 		cb->next = raidPtr->quiesce_wait_list;
    335 		raidPtr->quiesce_wait_list = cb;
    336 		suspended = RF_TRUE;
    337 		used_cb = 1;
    338 	}
    339 	RF_UNLOCK_MUTEX(raidPtr->access_suspend_mutex);
    340 
    341 	if ((need_cb == 1) && (used_cb == 0)) {
    342 		rf_FreeCallbackDesc(cb);
    343 	}
    344 
    345 #if RF_ACC_TRACE > 0
    346 	RF_ETIMER_STOP(timer);
    347 	RF_ETIMER_EVAL(timer);
    348 	tracerec->specific.user.suspend_ovhd_us += RF_ETIMER_VAL_US(timer);
    349 #endif
    350 
    351 #if RF_DEBUG_QUIESCE
    352 	if (suspended && rf_quiesceDebug)
    353 		printf("Stalling access due to quiescence lock\n");
    354 #endif
    355 	desc->state++;
    356 	return suspended;
    357 }
    358 
    359 int
    360 rf_State_Map(RF_RaidAccessDesc_t *desc)
    361 {
    362 	RF_Raid_t *raidPtr = desc->raidPtr;
    363 #if RF_ACC_TRACE > 0
    364 	RF_AccTraceEntry_t *tracerec = &desc->tracerec;
    365 	RF_Etimer_t timer;
    366 
    367 	RF_ETIMER_START(timer);
    368 #endif
    369 
    370 	if (!(desc->asmap = rf_MapAccess(raidPtr, desc->raidAddress, desc->numBlocks,
    371 		    desc->bufPtr, RF_DONT_REMAP)))
    372 		RF_PANIC();
    373 
    374 #if RF_ACC_TRACE > 0
    375 	RF_ETIMER_STOP(timer);
    376 	RF_ETIMER_EVAL(timer);
    377 	tracerec->specific.user.map_us = RF_ETIMER_VAL_US(timer);
    378 #endif
    379 
    380 	desc->state++;
    381 	return RF_FALSE;
    382 }
    383 
    384 int
    385 rf_State_Lock(RF_RaidAccessDesc_t *desc)
    386 {
    387 #if RF_ACC_TRACE > 0
    388 	RF_AccTraceEntry_t *tracerec = &desc->tracerec;
    389 	RF_Etimer_t timer;
    390 #endif
    391 	RF_Raid_t *raidPtr = desc->raidPtr;
    392 	RF_AccessStripeMapHeader_t *asmh = desc->asmap;
    393 	RF_AccessStripeMap_t *asm_p;
    394 	RF_StripeNum_t lastStripeID = -1;
    395 	int     suspended = RF_FALSE;
    396 
    397 #if RF_ACC_TRACE > 0
    398 	RF_ETIMER_START(timer);
    399 #endif
    400 
    401 	/* acquire each lock that we don't already hold */
    402 	for (asm_p = asmh->stripeMap; asm_p; asm_p = asm_p->next) {
    403 		RF_ASSERT(RF_IO_IS_R_OR_W(desc->type));
    404 		if (!rf_suppressLocksAndLargeWrites &&
    405 		    asm_p->parityInfo &&
    406 		    !(desc->flags & RF_DAG_SUPPRESS_LOCKS) &&
    407 		    !(asm_p->flags & RF_ASM_FLAGS_LOCK_TRIED)) {
    408 			asm_p->flags |= RF_ASM_FLAGS_LOCK_TRIED;
    409 				/* locks must be acquired hierarchically */
    410 			RF_ASSERT(asm_p->stripeID > lastStripeID);
    411 			lastStripeID = asm_p->stripeID;
    412 
    413 			RF_INIT_LOCK_REQ_DESC(asm_p->lockReqDesc, desc->type,
    414 					      (void (*) (struct buf *)) rf_ContinueRaidAccess, desc, asm_p,
    415 					      raidPtr->Layout.dataSectorsPerStripe);
    416 			if (rf_AcquireStripeLock(raidPtr->lockTable, asm_p->stripeID,
    417 						 &asm_p->lockReqDesc)) {
    418 				suspended = RF_TRUE;
    419 				break;
    420 			}
    421 		}
    422 		if (desc->type == RF_IO_TYPE_WRITE &&
    423 		    raidPtr->status == rf_rs_reconstructing) {
    424 			if (!(asm_p->flags & RF_ASM_FLAGS_FORCE_TRIED)) {
    425 				int     val;
    426 
    427 				asm_p->flags |= RF_ASM_FLAGS_FORCE_TRIED;
    428 				val = rf_ForceOrBlockRecon(raidPtr, asm_p,
    429 							   (void (*) (RF_Raid_t *, void *)) rf_ContinueRaidAccess, desc);
    430 				if (val == 0) {
    431 					asm_p->flags |= RF_ASM_FLAGS_RECON_BLOCKED;
    432 				} else {
    433 					suspended = RF_TRUE;
    434 					break;
    435 				}
    436 			} else {
    437 #if RF_DEBUG_PSS > 0
    438 				if (rf_pssDebug) {
    439 					printf("raid%d: skipping force/block because already done, psid %ld\n",
    440 					       desc->raidPtr->raidid,
    441 					       (long) asm_p->stripeID);
    442 				}
    443 #endif
    444 			}
    445 		} else {
    446 #if RF_DEBUG_PSS > 0
    447 			if (rf_pssDebug) {
    448 				printf("raid%d: skipping force/block because not write or not under recon, psid %ld\n",
    449 				       desc->raidPtr->raidid,
    450 				       (long) asm_p->stripeID);
    451 			}
    452 #endif
    453 		}
    454 	}
    455 #if RF_ACC_TRACE > 0
    456 	RF_ETIMER_STOP(timer);
    457 	RF_ETIMER_EVAL(timer);
    458 	tracerec->specific.user.lock_us += RF_ETIMER_VAL_US(timer);
    459 #endif
    460 	if (suspended)
    461 		return (RF_TRUE);
    462 
    463 	desc->state++;
    464 	return (RF_FALSE);
    465 }
    466 /*
    467  * the following three states create, execute, and post-process dags
    468  * the error recovery unit is a single dag.
    469  * by default, SelectAlgorithm creates an array of dags, one per parity stripe
    470  * in some tricky cases, multiple dags per stripe are created
    471  *   - dags within a parity stripe are executed sequentially (arbitrary order)
    472  *   - dags for distinct parity stripes are executed concurrently
    473  *
    474  * repeat until all dags complete successfully -or- dag selection fails
    475  *
    476  * while !done
    477  *   create dag(s) (SelectAlgorithm)
    478  *   if dag
    479  *     execute dag (DispatchDAG)
    480  *     if dag successful
    481  *       done (SUCCESS)
    482  *     else
    483  *       !done (RETRY - start over with new dags)
    484  *   else
    485  *     done (FAIL)
    486  */
    487 int
    488 rf_State_CreateDAG(RF_RaidAccessDesc_t *desc)
    489 {
    490 #if RF_ACC_TRACE > 0
    491 	RF_AccTraceEntry_t *tracerec = &desc->tracerec;
    492 	RF_Etimer_t timer;
    493 #endif
    494 	RF_DagHeader_t *dag_h;
    495 	RF_DagList_t *dagList;
    496 	struct buf *bp;
    497 	int     i, selectStatus;
    498 
    499 	/* generate a dag for the access, and fire it off.  When the dag
    500 	 * completes, we'll get re-invoked in the next state. */
    501 #if RF_ACC_TRACE > 0
    502 	RF_ETIMER_START(timer);
    503 #endif
    504 	/* SelectAlgorithm returns one or more dags */
    505 	selectStatus = rf_SelectAlgorithm(desc, desc->flags | RF_DAG_SUPPRESS_LOCKS);
    506 #if RF_DEBUG_VALIDATE_DAG
    507 	if (rf_printDAGsDebug) {
    508 		dagList = desc->dagList;
    509 		for (i = 0; i < desc->numStripes; i++) {
    510 			rf_PrintDAGList(dagList->dags);
    511 			dagList = dagList->next;
    512 		}
    513 	}
    514 #endif /* RF_DEBUG_VALIDATE_DAG */
    515 #if RF_ACC_TRACE > 0
    516 	RF_ETIMER_STOP(timer);
    517 	RF_ETIMER_EVAL(timer);
    518 	/* update time to create all dags */
    519 	tracerec->specific.user.dag_create_us = RF_ETIMER_VAL_US(timer);
    520 #endif
    521 
    522 	desc->status = 0;	/* good status */
    523 
    524 	if (selectStatus || (desc->numRetries > RF_RETRY_THRESHOLD)) {
    525 		/* failed to create a dag */
    526 		/* this happens when there are too many faults or incomplete
    527 		 * dag libraries */
    528 		if (selectStatus) {
    529 			printf("raid%d: failed to create a dag. "
    530 			       "Too many component failures.\n",
    531 			       desc->raidPtr->raidid);
    532 		} else {
    533 			printf("raid%d: IO failed after %d retries.\n",
    534 			       desc->raidPtr->raidid, RF_RETRY_THRESHOLD);
    535 		}
    536 
    537 		desc->status = 1; /* bad status */
    538 		/* skip straight to rf_State_Cleanup() */
    539 		desc->state = rf_CleanupState;
    540 		bp = (struct buf *)desc->bp;
    541 		bp->b_error = EIO;
    542 		bp->b_resid = bp->b_bcount;
    543 	} else {
    544 		/* bind dags to desc */
    545 		dagList = desc->dagList;
    546 		for (i = 0; i < desc->numStripes; i++) {
    547 			dag_h = dagList->dags;
    548 			while (dag_h) {
    549 				dag_h->bp = (struct buf *) desc->bp;
    550 #if RF_ACC_TRACE > 0
    551 				dag_h->tracerec = tracerec;
    552 #endif
    553 				dag_h = dag_h->next;
    554 			}
    555 			dagList = dagList->next;
    556 		}
    557 		desc->flags |= RF_DAG_DISPATCH_RETURNED;
    558 		desc->state++;	/* next state should be rf_State_ExecuteDAG */
    559 	}
    560 	return RF_FALSE;
    561 }
    562 
    563 
    564 
    565 /* the access has an list of dagLists, one dagList per parity stripe.
    566  * fire the first dag in each parity stripe (dagList).
    567  * dags within a stripe (dagList) must be executed sequentially
    568  *  - this preserves atomic parity update
    569  * dags for independents parity groups (stripes) are fired concurrently */
    570 
    571 int
    572 rf_State_ExecuteDAG(RF_RaidAccessDesc_t *desc)
    573 {
    574 	int     i;
    575 	RF_DagHeader_t *dag_h;
    576 	RF_DagList_t *dagList;
    577 
    578 	/* next state is always rf_State_ProcessDAG important to do
    579 	 * this before firing the first dag (it may finish before we
    580 	 * leave this routine) */
    581 	desc->state++;
    582 
    583 	/* sweep dag array, a stripe at a time, firing the first dag
    584 	 * in each stripe */
    585 	dagList = desc->dagList;
    586 	for (i = 0; i < desc->numStripes; i++) {
    587 		RF_ASSERT(dagList->numDags > 0);
    588 		RF_ASSERT(dagList->numDagsDone == 0);
    589 		RF_ASSERT(dagList->numDagsFired == 0);
    590 #if RF_ACC_TRACE > 0
    591 		RF_ETIMER_START(dagList->tracerec.timer);
    592 #endif
    593 		/* fire first dag in this stripe */
    594 		dag_h = dagList->dags;
    595 		RF_ASSERT(dag_h);
    596 		dagList->numDagsFired++;
    597 		rf_DispatchDAG(dag_h, (void (*) (void *)) rf_ContinueDagAccess, dagList);
    598 		dagList = dagList->next;
    599 	}
    600 
    601 	/* the DAG will always call the callback, even if there was no
    602 	 * blocking, so we are always suspended in this state */
    603 	return RF_TRUE;
    604 }
    605 
    606 
    607 
    608 /* rf_State_ProcessDAG is entered when a dag completes.
    609  * first, check to all dags in the access have completed
    610  * if not, fire as many dags as possible */
    611 
    612 int
    613 rf_State_ProcessDAG(RF_RaidAccessDesc_t *desc)
    614 {
    615 	RF_AccessStripeMapHeader_t *asmh = desc->asmap;
    616 	RF_Raid_t *raidPtr = desc->raidPtr;
    617 	RF_DagHeader_t *dag_h;
    618 	int     i, j, done = RF_TRUE;
    619 	RF_DagList_t *dagList, *temp;
    620 
    621 	/* check to see if this is the last dag */
    622 	dagList = desc->dagList;
    623 	for (i = 0; i < desc->numStripes; i++) {
    624 		if (dagList->numDags != dagList->numDagsDone)
    625 			done = RF_FALSE;
    626 		dagList = dagList->next;
    627 	}
    628 
    629 	if (done) {
    630 		if (desc->status) {
    631 			/* a dag failed, retry */
    632 			/* free all dags */
    633 			dagList = desc->dagList;
    634 			for (i = 0; i < desc->numStripes; i++) {
    635 				rf_FreeDAG(dagList->dags);
    636 				temp = dagList;
    637 				dagList = dagList->next;
    638 				rf_FreeDAGList(temp);
    639 			}
    640 			desc->dagList = NULL;
    641 
    642 			rf_MarkFailuresInASMList(raidPtr, asmh);
    643 
    644 			/* note the retry so that we'll bail in
    645 			   rf_State_CreateDAG() once we've retired
    646 			   the IO RF_RETRY_THRESHOLD times */
    647 
    648 			desc->numRetries++;
    649 
    650 			/* back up to rf_State_CreateDAG */
    651 			desc->state = desc->state - 2;
    652 			return RF_FALSE;
    653 		} else {
    654 			/* move on to rf_State_Cleanup */
    655 			desc->state++;
    656 		}
    657 		return RF_FALSE;
    658 	} else {
    659 		/* more dags to execute */
    660 		/* see if any are ready to be fired.  if so, fire them */
    661 		/* don't fire the initial dag in a list, it's fired in
    662 		 * rf_State_ExecuteDAG */
    663 		dagList = desc->dagList;
    664 		for (i = 0; i < desc->numStripes; i++) {
    665 			if ((dagList->numDagsDone < dagList->numDags)
    666 			    && (dagList->numDagsDone == dagList->numDagsFired)
    667 			    && (dagList->numDagsFired > 0)) {
    668 #if RF_ACC_TRACE > 0
    669 				RF_ETIMER_START(dagList->tracerec.timer);
    670 #endif
    671 				/* fire next dag in this stripe */
    672 				/* first, skip to next dag awaiting execution */
    673 				dag_h = dagList->dags;
    674 				for (j = 0; j < dagList->numDagsDone; j++)
    675 					dag_h = dag_h->next;
    676 				dagList->numDagsFired++;
    677 				rf_DispatchDAG(dag_h, (void (*) (void *)) rf_ContinueDagAccess,
    678 				    dagList);
    679 			}
    680 			dagList = dagList->next;
    681 		}
    682 		return RF_TRUE;
    683 	}
    684 }
    685 /* only make it this far if all dags complete successfully */
    686 int
    687 rf_State_Cleanup(RF_RaidAccessDesc_t *desc)
    688 {
    689 #if RF_ACC_TRACE > 0
    690 	RF_AccTraceEntry_t *tracerec = &desc->tracerec;
    691 	RF_Etimer_t timer;
    692 #endif
    693 	RF_AccessStripeMapHeader_t *asmh = desc->asmap;
    694 	RF_Raid_t *raidPtr = desc->raidPtr;
    695 	RF_AccessStripeMap_t *asm_p;
    696 	RF_DagList_t *dagList;
    697 	int i;
    698 
    699 	desc->state++;
    700 
    701 #if RF_ACC_TRACE > 0
    702 	timer = tracerec->timer;
    703 	RF_ETIMER_STOP(timer);
    704 	RF_ETIMER_EVAL(timer);
    705 	tracerec->specific.user.dag_retry_us = RF_ETIMER_VAL_US(timer);
    706 
    707 	/* the RAID I/O is complete.  Clean up. */
    708 	tracerec->specific.user.dag_retry_us = 0;
    709 
    710 	RF_ETIMER_START(timer);
    711 #endif
    712 	/* free all dags */
    713 	dagList = desc->dagList;
    714 	for (i = 0; i < desc->numStripes; i++) {
    715 		rf_FreeDAG(dagList->dags);
    716 		dagList = dagList->next;
    717 	}
    718 #if RF_ACC_TRACE > 0
    719 	RF_ETIMER_STOP(timer);
    720 	RF_ETIMER_EVAL(timer);
    721 	tracerec->specific.user.cleanup_us = RF_ETIMER_VAL_US(timer);
    722 
    723 	RF_ETIMER_START(timer);
    724 #endif
    725 	for (asm_p = asmh->stripeMap; asm_p; asm_p = asm_p->next) {
    726 		if (!rf_suppressLocksAndLargeWrites &&
    727 		    asm_p->parityInfo &&
    728 		    !(desc->flags & RF_DAG_SUPPRESS_LOCKS)) {
    729 			RF_ASSERT_VALID_LOCKREQ(&asm_p->lockReqDesc);
    730 			rf_ReleaseStripeLock(raidPtr->lockTable,
    731 					     asm_p->stripeID,
    732 					     &asm_p->lockReqDesc);
    733 		}
    734 		if (asm_p->flags & RF_ASM_FLAGS_RECON_BLOCKED) {
    735 			rf_UnblockRecon(raidPtr, asm_p);
    736 		}
    737 	}
    738 #if RF_ACC_TRACE > 0
    739 	RF_ETIMER_STOP(timer);
    740 	RF_ETIMER_EVAL(timer);
    741 	tracerec->specific.user.lock_us += RF_ETIMER_VAL_US(timer);
    742 
    743 	RF_ETIMER_START(timer);
    744 #endif
    745 	rf_FreeAccessStripeMap(asmh);
    746 #if RF_ACC_TRACE > 0
    747 	RF_ETIMER_STOP(timer);
    748 	RF_ETIMER_EVAL(timer);
    749 	tracerec->specific.user.cleanup_us += RF_ETIMER_VAL_US(timer);
    750 
    751 	RF_ETIMER_STOP(desc->timer);
    752 	RF_ETIMER_EVAL(desc->timer);
    753 
    754 	timer = desc->tracerec.tot_timer;
    755 	RF_ETIMER_STOP(timer);
    756 	RF_ETIMER_EVAL(timer);
    757 	desc->tracerec.total_us = RF_ETIMER_VAL_US(timer);
    758 
    759 	rf_LogTraceRec(raidPtr, tracerec);
    760 #endif
    761 	desc->flags |= RF_DAG_ACCESS_COMPLETE;
    762 
    763 	return RF_FALSE;
    764 }
    765