xref: /netbsd-src/sys/dev/raidframe/rf_paritylogging.c (revision 08c81a9c2dc8c7300e893321eb65c0925d60871c)
1 /*	$NetBSD: rf_paritylogging.c,v 1.13 2002/09/14 17:53:58 oster Exp $	*/
2 /*
3  * Copyright (c) 1995 Carnegie-Mellon University.
4  * All rights reserved.
5  *
6  * Author: William V. Courtright II
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@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 
30 /*
31   parity logging configuration, dag selection, and mapping is implemented here
32  */
33 
34 #include <sys/cdefs.h>
35 __KERNEL_RCSID(0, "$NetBSD: rf_paritylogging.c,v 1.13 2002/09/14 17:53:58 oster Exp $");
36 
37 #include "rf_archs.h"
38 
39 #if RF_INCLUDE_PARITYLOGGING > 0
40 
41 #include <dev/raidframe/raidframevar.h>
42 
43 #include "rf_raid.h"
44 #include "rf_dag.h"
45 #include "rf_dagutils.h"
46 #include "rf_dagfuncs.h"
47 #include "rf_dagffrd.h"
48 #include "rf_dagffwr.h"
49 #include "rf_dagdegrd.h"
50 #include "rf_dagdegwr.h"
51 #include "rf_paritylog.h"
52 #include "rf_paritylogDiskMgr.h"
53 #include "rf_paritylogging.h"
54 #include "rf_parityloggingdags.h"
55 #include "rf_general.h"
56 #include "rf_map.h"
57 #include "rf_utils.h"
58 #include "rf_shutdown.h"
59 
60 typedef struct RF_ParityLoggingConfigInfo_s {
61 	RF_RowCol_t **stripeIdentifier;	/* filled in at config time & used by
62 					 * IdentifyStripe */
63 }       RF_ParityLoggingConfigInfo_t;
64 
65 static void FreeRegionInfo(RF_Raid_t * raidPtr, RF_RegionId_t regionID);
66 static void rf_ShutdownParityLogging(RF_ThreadArg_t arg);
67 static void rf_ShutdownParityLoggingRegionInfo(RF_ThreadArg_t arg);
68 static void rf_ShutdownParityLoggingPool(RF_ThreadArg_t arg);
69 static void rf_ShutdownParityLoggingRegionBufferPool(RF_ThreadArg_t arg);
70 static void rf_ShutdownParityLoggingParityBufferPool(RF_ThreadArg_t arg);
71 static void rf_ShutdownParityLoggingDiskQueue(RF_ThreadArg_t arg);
72 
73 int
74 rf_ConfigureParityLogging(
75     RF_ShutdownList_t ** listp,
76     RF_Raid_t * raidPtr,
77     RF_Config_t * cfgPtr)
78 {
79 	int     i, j, startdisk, rc;
80 	RF_SectorCount_t totalLogCapacity, fragmentation, lastRegionCapacity;
81 	RF_SectorCount_t parityBufferCapacity, maxRegionParityRange;
82 	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
83 	RF_ParityLoggingConfigInfo_t *info;
84 	RF_ParityLog_t *l = NULL, *next;
85 	caddr_t lHeapPtr;
86 
87 	if (rf_numParityRegions <= 0)
88 		return(EINVAL);
89 
90 	/*
91          * We create multiple entries on the shutdown list here, since
92          * this configuration routine is fairly complicated in and of
93          * itself, and this makes backing out of a failed configuration
94          * much simpler.
95          */
96 
97 	raidPtr->numSectorsPerLog = RF_DEFAULT_NUM_SECTORS_PER_LOG;
98 
99 	/* create a parity logging configuration structure */
100 	RF_MallocAndAdd(info, sizeof(RF_ParityLoggingConfigInfo_t),
101 			(RF_ParityLoggingConfigInfo_t *),
102 			raidPtr->cleanupList);
103 	if (info == NULL)
104 		return (ENOMEM);
105 	layoutPtr->layoutSpecificInfo = (void *) info;
106 
107 	RF_ASSERT(raidPtr->numRow == 1);
108 
109 	/* the stripe identifier must identify the disks in each stripe, IN
110 	 * THE ORDER THAT THEY APPEAR IN THE STRIPE. */
111 	info->stripeIdentifier = rf_make_2d_array((raidPtr->numCol),
112 						  (raidPtr->numCol),
113 						  raidPtr->cleanupList);
114 	if (info->stripeIdentifier == NULL)
115 		return (ENOMEM);
116 
117 	startdisk = 0;
118 	for (i = 0; i < (raidPtr->numCol); i++) {
119 		for (j = 0; j < (raidPtr->numCol); j++) {
120 			info->stripeIdentifier[i][j] = (startdisk + j) %
121 				(raidPtr->numCol - 1);
122 		}
123 		if ((--startdisk) < 0)
124 			startdisk = raidPtr->numCol - 1 - 1;
125 	}
126 
127 	/* fill in the remaining layout parameters */
128 	layoutPtr->numStripe = layoutPtr->stripeUnitsPerDisk;
129 	layoutPtr->bytesPerStripeUnit = layoutPtr->sectorsPerStripeUnit <<
130 		raidPtr->logBytesPerSector;
131 	layoutPtr->numParityCol = 1;
132 	layoutPtr->numParityLogCol = 1;
133 	layoutPtr->numDataCol = raidPtr->numCol - layoutPtr->numParityCol -
134 		layoutPtr->numParityLogCol;
135 	layoutPtr->dataSectorsPerStripe = layoutPtr->numDataCol *
136 		layoutPtr->sectorsPerStripeUnit;
137 	layoutPtr->dataStripeUnitsPerDisk = layoutPtr->stripeUnitsPerDisk;
138 	raidPtr->sectorsPerDisk = layoutPtr->stripeUnitsPerDisk *
139 		layoutPtr->sectorsPerStripeUnit;
140 
141 	raidPtr->totalSectors = layoutPtr->stripeUnitsPerDisk *
142 		layoutPtr->numDataCol * layoutPtr->sectorsPerStripeUnit;
143 
144 	/* configure parity log parameters
145 	 *
146 	 * parameter               comment/constraints
147 	 * -------------------------------------------
148 	 * numParityRegions*       all regions (except possibly last)
149 	 *                         of equal size
150 	 * totalInCoreLogCapacity* amount of memory in bytes available
151 	 *                         for in-core logs (default 1 MB)
152 	 * numSectorsPerLog#       capacity of an in-core log in sectors
153 	 *                         (1 * disk track)
154 	 * numParityLogs           total number of in-core logs,
155 	 *                         should be at least numParityRegions
156 	 * regionLogCapacity       size of a region log (except possibly
157 	 *                         last one) in sectors
158 	 * totalLogCapacity        total amount of log space in sectors
159 	 *
160 	 * where '*' denotes a user settable parameter.
161 	 * Note that logs are fixed to be the size of a disk track,
162 	 * value #defined in rf_paritylog.h
163 	 *
164 	 */
165 
166 	totalLogCapacity = layoutPtr->stripeUnitsPerDisk * layoutPtr->sectorsPerStripeUnit * layoutPtr->numParityLogCol;
167 	raidPtr->regionLogCapacity = totalLogCapacity / rf_numParityRegions;
168 	if (rf_parityLogDebug)
169 		printf("bytes per sector %d\n", raidPtr->bytesPerSector);
170 
171 	/* reduce fragmentation within a disk region by adjusting the number
172 	 * of regions in an attempt to allow an integral number of logs to fit
173 	 * into a disk region */
174 	fragmentation = raidPtr->regionLogCapacity % raidPtr->numSectorsPerLog;
175 	if (fragmentation > 0)
176 		for (i = 1; i < (raidPtr->numSectorsPerLog / 2); i++) {
177 			if (((totalLogCapacity / (rf_numParityRegions + i)) %
178 			     raidPtr->numSectorsPerLog) < fragmentation) {
179 				rf_numParityRegions++;
180 				raidPtr->regionLogCapacity = totalLogCapacity /
181 					rf_numParityRegions;
182 				fragmentation = raidPtr->regionLogCapacity %
183 					raidPtr->numSectorsPerLog;
184 			}
185 			if (((totalLogCapacity / (rf_numParityRegions - i)) %
186 			     raidPtr->numSectorsPerLog) < fragmentation) {
187 				rf_numParityRegions--;
188 				raidPtr->regionLogCapacity = totalLogCapacity /
189 					rf_numParityRegions;
190 				fragmentation = raidPtr->regionLogCapacity %
191 					raidPtr->numSectorsPerLog;
192 			}
193 		}
194 	/* ensure integral number of regions per log */
195 	raidPtr->regionLogCapacity = (raidPtr->regionLogCapacity /
196 				      raidPtr->numSectorsPerLog) *
197 		raidPtr->numSectorsPerLog;
198 
199 	raidPtr->numParityLogs = rf_totalInCoreLogCapacity /
200 		(raidPtr->bytesPerSector * raidPtr->numSectorsPerLog);
201 	/* to avoid deadlock, must ensure that enough logs exist for each
202 	 * region to have one simultaneously */
203 	if (raidPtr->numParityLogs < rf_numParityRegions)
204 		raidPtr->numParityLogs = rf_numParityRegions;
205 
206 	/* create region information structs */
207 	printf("Allocating %d bytes for in-core parity region info\n",
208 	       (int) (rf_numParityRegions * sizeof(RF_RegionInfo_t)));
209 	RF_Malloc(raidPtr->regionInfo,
210 		  (rf_numParityRegions * sizeof(RF_RegionInfo_t)),
211 		  (RF_RegionInfo_t *));
212 	if (raidPtr->regionInfo == NULL)
213 		return (ENOMEM);
214 
215 	/* last region may not be full capacity */
216 	lastRegionCapacity = raidPtr->regionLogCapacity;
217 	while ((rf_numParityRegions - 1) * raidPtr->regionLogCapacity +
218 	       lastRegionCapacity > totalLogCapacity)
219 		lastRegionCapacity = lastRegionCapacity -
220 			raidPtr->numSectorsPerLog;
221 
222 	raidPtr->regionParityRange = raidPtr->sectorsPerDisk /
223 		rf_numParityRegions;
224 	maxRegionParityRange = raidPtr->regionParityRange;
225 
226 /* i can't remember why this line is in the code -wvcii 6/30/95 */
227 /*  if (raidPtr->sectorsPerDisk % rf_numParityRegions > 0)
228     regionParityRange++; */
229 
230 	/* build pool of unused parity logs */
231 	printf("Allocating %d bytes for %d parity logs\n",
232 	       raidPtr->numParityLogs * raidPtr->numSectorsPerLog *
233 	       raidPtr->bytesPerSector,
234 	       raidPtr->numParityLogs);
235 	RF_Malloc(raidPtr->parityLogBufferHeap, raidPtr->numParityLogs *
236 		  raidPtr->numSectorsPerLog * raidPtr->bytesPerSector,
237 		  (caddr_t));
238 	if (raidPtr->parityLogBufferHeap == NULL)
239 		return (ENOMEM);
240 	lHeapPtr = raidPtr->parityLogBufferHeap;
241 	rc = rf_mutex_init(&raidPtr->parityLogPool.mutex);
242 	if (rc) {
243 		rf_print_unable_to_init_mutex(__FILE__, __LINE__, rc);
244 		RF_Free(raidPtr->parityLogBufferHeap, raidPtr->numParityLogs *
245 			raidPtr->numSectorsPerLog * raidPtr->bytesPerSector);
246 		return (ENOMEM);
247 	}
248 	for (i = 0; i < raidPtr->numParityLogs; i++) {
249 		if (i == 0) {
250 			RF_Calloc(raidPtr->parityLogPool.parityLogs, 1,
251 				  sizeof(RF_ParityLog_t), (RF_ParityLog_t *));
252 			if (raidPtr->parityLogPool.parityLogs == NULL) {
253 				RF_Free(raidPtr->parityLogBufferHeap,
254 					raidPtr->numParityLogs *
255 					raidPtr->numSectorsPerLog *
256 					raidPtr->bytesPerSector);
257 				return (ENOMEM);
258 			}
259 			l = raidPtr->parityLogPool.parityLogs;
260 		} else {
261 			RF_Calloc(l->next, 1, sizeof(RF_ParityLog_t),
262 				  (RF_ParityLog_t *));
263 			if (l->next == NULL) {
264 				RF_Free(raidPtr->parityLogBufferHeap,
265 					raidPtr->numParityLogs *
266 					raidPtr->numSectorsPerLog *
267 					raidPtr->bytesPerSector);
268 				for (l = raidPtr->parityLogPool.parityLogs;
269 				     l;
270 				     l = next) {
271 					next = l->next;
272 					if (l->records)
273 						RF_Free(l->records, (raidPtr->numSectorsPerLog * sizeof(RF_ParityLogRecord_t)));
274 					RF_Free(l, sizeof(RF_ParityLog_t));
275 				}
276 				return (ENOMEM);
277 			}
278 			l = l->next;
279 		}
280 		l->bufPtr = lHeapPtr;
281 		lHeapPtr += raidPtr->numSectorsPerLog *
282 			raidPtr->bytesPerSector;
283 		RF_Malloc(l->records, (raidPtr->numSectorsPerLog *
284 				       sizeof(RF_ParityLogRecord_t)),
285 			  (RF_ParityLogRecord_t *));
286 		if (l->records == NULL) {
287 			RF_Free(raidPtr->parityLogBufferHeap,
288 				raidPtr->numParityLogs *
289 				raidPtr->numSectorsPerLog *
290 				raidPtr->bytesPerSector);
291 			for (l = raidPtr->parityLogPool.parityLogs;
292 			     l;
293 			     l = next) {
294 				next = l->next;
295 				if (l->records)
296 					RF_Free(l->records,
297 						(raidPtr->numSectorsPerLog *
298 						 sizeof(RF_ParityLogRecord_t)));
299 				RF_Free(l, sizeof(RF_ParityLog_t));
300 			}
301 			return (ENOMEM);
302 		}
303 	}
304 	rc = rf_ShutdownCreate(listp, rf_ShutdownParityLoggingPool, raidPtr);
305 	if (rc) {
306 		RF_ERRORMSG3("Unable to create shutdown entry file %s line %d rc=%d\n", __FILE__,
307 		    __LINE__, rc);
308 		rf_ShutdownParityLoggingPool(raidPtr);
309 		return (rc);
310 	}
311 	/* build pool of region buffers */
312 	rc = rf_mutex_init(&raidPtr->regionBufferPool.mutex);
313 	if (rc) {
314 		rf_print_unable_to_init_mutex(__FILE__, __LINE__, rc);
315 		return (ENOMEM);
316 	}
317 	rc = rf_cond_init(&raidPtr->regionBufferPool.cond);
318 	if (rc) {
319 		rf_print_unable_to_init_cond(__FILE__, __LINE__, rc);
320 		rf_mutex_destroy(&raidPtr->regionBufferPool.mutex);
321 		return (ENOMEM);
322 	}
323 	raidPtr->regionBufferPool.bufferSize = raidPtr->regionLogCapacity *
324 		raidPtr->bytesPerSector;
325 	printf("regionBufferPool.bufferSize %d\n",
326 	       raidPtr->regionBufferPool.bufferSize);
327 
328 	/* for now, only one region at a time may be reintegrated */
329 	raidPtr->regionBufferPool.totalBuffers = 1;
330 
331 	raidPtr->regionBufferPool.availableBuffers =
332 		raidPtr->regionBufferPool.totalBuffers;
333 	raidPtr->regionBufferPool.availBuffersIndex = 0;
334 	raidPtr->regionBufferPool.emptyBuffersIndex = 0;
335 	printf("Allocating %d bytes for regionBufferPool\n",
336 	       (int) (raidPtr->regionBufferPool.totalBuffers *
337 		      sizeof(caddr_t)));
338 	RF_Malloc(raidPtr->regionBufferPool.buffers,
339 		  raidPtr->regionBufferPool.totalBuffers * sizeof(caddr_t),
340 		  (caddr_t *));
341 	if (raidPtr->regionBufferPool.buffers == NULL) {
342 		rf_mutex_destroy(&raidPtr->regionBufferPool.mutex);
343 		rf_cond_destroy(&raidPtr->regionBufferPool.cond);
344 		return (ENOMEM);
345 	}
346 	for (i = 0; i < raidPtr->regionBufferPool.totalBuffers; i++) {
347 		printf("Allocating %d bytes for regionBufferPool#%d\n",
348 		       (int) (raidPtr->regionBufferPool.bufferSize *
349 			      sizeof(char)), i);
350 		RF_Malloc(raidPtr->regionBufferPool.buffers[i],
351 			  raidPtr->regionBufferPool.bufferSize * sizeof(char),
352 			  (caddr_t));
353 		if (raidPtr->regionBufferPool.buffers[i] == NULL) {
354 			rf_mutex_destroy(&raidPtr->regionBufferPool.mutex);
355 			rf_cond_destroy(&raidPtr->regionBufferPool.cond);
356 			for (j = 0; j < i; j++) {
357 				RF_Free(raidPtr->regionBufferPool.buffers[i],
358 					raidPtr->regionBufferPool.bufferSize *
359 					sizeof(char));
360 			}
361 			RF_Free(raidPtr->regionBufferPool.buffers,
362 				raidPtr->regionBufferPool.totalBuffers *
363 				sizeof(caddr_t));
364 			return (ENOMEM);
365 		}
366 		printf("raidPtr->regionBufferPool.buffers[%d] = %lx\n", i,
367 		    (long) raidPtr->regionBufferPool.buffers[i]);
368 	}
369 	rc = rf_ShutdownCreate(listp,
370 			       rf_ShutdownParityLoggingRegionBufferPool,
371 			       raidPtr);
372 	if (rc) {
373 		RF_ERRORMSG3("Unable to create shutdown entry file %s line %d rc=%d\n", __FILE__,
374 		    __LINE__, rc);
375 		rf_ShutdownParityLoggingRegionBufferPool(raidPtr);
376 		return (rc);
377 	}
378 	/* build pool of parity buffers */
379 	parityBufferCapacity = maxRegionParityRange;
380 	rc = rf_mutex_init(&raidPtr->parityBufferPool.mutex);
381 	if (rc) {
382 		rf_print_unable_to_init_mutex(__FILE__, __LINE__, rc);
383 		return (rc);
384 	}
385 	rc = rf_cond_init(&raidPtr->parityBufferPool.cond);
386 	if (rc) {
387 		rf_print_unable_to_init_cond(__FILE__, __LINE__, rc);
388 		rf_mutex_destroy(&raidPtr->parityBufferPool.mutex);
389 		return (ENOMEM);
390 	}
391 	raidPtr->parityBufferPool.bufferSize = parityBufferCapacity *
392 		raidPtr->bytesPerSector;
393 	printf("parityBufferPool.bufferSize %d\n",
394 	       raidPtr->parityBufferPool.bufferSize);
395 
396 	/* for now, only one region at a time may be reintegrated */
397 	raidPtr->parityBufferPool.totalBuffers = 1;
398 
399 	raidPtr->parityBufferPool.availableBuffers =
400 		raidPtr->parityBufferPool.totalBuffers;
401 	raidPtr->parityBufferPool.availBuffersIndex = 0;
402 	raidPtr->parityBufferPool.emptyBuffersIndex = 0;
403 	printf("Allocating %d bytes for parityBufferPool of %d units\n",
404 	       (int) (raidPtr->parityBufferPool.totalBuffers *
405 		      sizeof(caddr_t)),
406 	       raidPtr->parityBufferPool.totalBuffers );
407 	RF_Malloc(raidPtr->parityBufferPool.buffers,
408 		  raidPtr->parityBufferPool.totalBuffers * sizeof(caddr_t),
409 		  (caddr_t *));
410 	if (raidPtr->parityBufferPool.buffers == NULL) {
411 		rf_mutex_destroy(&raidPtr->parityBufferPool.mutex);
412 		rf_cond_destroy(&raidPtr->parityBufferPool.cond);
413 		return (ENOMEM);
414 	}
415 	for (i = 0; i < raidPtr->parityBufferPool.totalBuffers; i++) {
416 		printf("Allocating %d bytes for parityBufferPool#%d\n",
417 		       (int) (raidPtr->parityBufferPool.bufferSize *
418 			      sizeof(char)),i);
419 		RF_Malloc(raidPtr->parityBufferPool.buffers[i],
420 			  raidPtr->parityBufferPool.bufferSize * sizeof(char),
421 			  (caddr_t));
422 		if (raidPtr->parityBufferPool.buffers == NULL) {
423 			rf_mutex_destroy(&raidPtr->parityBufferPool.mutex);
424 			rf_cond_destroy(&raidPtr->parityBufferPool.cond);
425 			for (j = 0; j < i; j++) {
426 				RF_Free(raidPtr->parityBufferPool.buffers[i],
427 					raidPtr->regionBufferPool.bufferSize *
428 					sizeof(char));
429 			}
430 			RF_Free(raidPtr->parityBufferPool.buffers,
431 				raidPtr->regionBufferPool.totalBuffers *
432 				sizeof(caddr_t));
433 			return (ENOMEM);
434 		}
435 		printf("parityBufferPool.buffers[%d] = %lx\n", i,
436 		    (long) raidPtr->parityBufferPool.buffers[i]);
437 	}
438 	rc = rf_ShutdownCreate(listp,
439 			       rf_ShutdownParityLoggingParityBufferPool,
440 			       raidPtr);
441 	if (rc) {
442 		RF_ERRORMSG3("Unable to create shutdown entry file %s line %d rc=%d\n", __FILE__,
443 		    __LINE__, rc);
444 		rf_ShutdownParityLoggingParityBufferPool(raidPtr);
445 		return (rc);
446 	}
447 	/* initialize parityLogDiskQueue */
448 	rc = rf_create_managed_mutex(listp,
449 				     &raidPtr->parityLogDiskQueue.mutex);
450 	if (rc) {
451 		rf_print_unable_to_init_mutex(__FILE__, __LINE__, rc);
452 		return (rc);
453 	}
454 	rc = rf_create_managed_cond(listp, &raidPtr->parityLogDiskQueue.cond);
455 	if (rc) {
456 		rf_print_unable_to_init_cond(__FILE__, __LINE__, rc);
457 		return (rc);
458 	}
459 	raidPtr->parityLogDiskQueue.flushQueue = NULL;
460 	raidPtr->parityLogDiskQueue.reintQueue = NULL;
461 	raidPtr->parityLogDiskQueue.bufHead = NULL;
462 	raidPtr->parityLogDiskQueue.bufTail = NULL;
463 	raidPtr->parityLogDiskQueue.reintHead = NULL;
464 	raidPtr->parityLogDiskQueue.reintTail = NULL;
465 	raidPtr->parityLogDiskQueue.logBlockHead = NULL;
466 	raidPtr->parityLogDiskQueue.logBlockTail = NULL;
467 	raidPtr->parityLogDiskQueue.reintBlockHead = NULL;
468 	raidPtr->parityLogDiskQueue.reintBlockTail = NULL;
469 	raidPtr->parityLogDiskQueue.freeDataList = NULL;
470 	raidPtr->parityLogDiskQueue.freeCommonList = NULL;
471 
472 	rc = rf_ShutdownCreate(listp,
473 			       rf_ShutdownParityLoggingDiskQueue,
474 			       raidPtr);
475 	if (rc) {
476 		RF_ERRORMSG3("Unable to create shutdown entry file %s line %d rc=%d\n", __FILE__,
477 		    __LINE__, rc);
478 		return (rc);
479 	}
480 	for (i = 0; i < rf_numParityRegions; i++) {
481 		rc = rf_mutex_init(&raidPtr->regionInfo[i].mutex);
482 		if (rc) {
483 			rf_print_unable_to_init_mutex(__FILE__, __LINE__, rc);
484 			for (j = 0; j < i; j++)
485 				FreeRegionInfo(raidPtr, j);
486 			RF_Free(raidPtr->regionInfo,
487 				(rf_numParityRegions *
488 				 sizeof(RF_RegionInfo_t)));
489 			return (ENOMEM);
490 		}
491 		rc = rf_mutex_init(&raidPtr->regionInfo[i].reintMutex);
492 		if (rc) {
493 			rf_print_unable_to_init_mutex(__FILE__, __LINE__, rc);
494 			rf_mutex_destroy(&raidPtr->regionInfo[i].mutex);
495 			for (j = 0; j < i; j++)
496 				FreeRegionInfo(raidPtr, j);
497 			RF_Free(raidPtr->regionInfo,
498 				(rf_numParityRegions *
499 				 sizeof(RF_RegionInfo_t)));
500 			return (ENOMEM);
501 		}
502 		raidPtr->regionInfo[i].reintInProgress = RF_FALSE;
503 		raidPtr->regionInfo[i].regionStartAddr =
504 			raidPtr->regionLogCapacity * i;
505 		raidPtr->regionInfo[i].parityStartAddr =
506 			raidPtr->regionParityRange * i;
507 		if (i < rf_numParityRegions - 1) {
508 			raidPtr->regionInfo[i].capacity =
509 				raidPtr->regionLogCapacity;
510 			raidPtr->regionInfo[i].numSectorsParity =
511 				raidPtr->regionParityRange;
512 		} else {
513 			raidPtr->regionInfo[i].capacity =
514 				lastRegionCapacity;
515 			raidPtr->regionInfo[i].numSectorsParity =
516 				raidPtr->sectorsPerDisk -
517 				raidPtr->regionParityRange * i;
518 			if (raidPtr->regionInfo[i].numSectorsParity >
519 			    maxRegionParityRange)
520 				maxRegionParityRange =
521 					raidPtr->regionInfo[i].numSectorsParity;
522 		}
523 		raidPtr->regionInfo[i].diskCount = 0;
524 		RF_ASSERT(raidPtr->regionInfo[i].capacity +
525 			  raidPtr->regionInfo[i].regionStartAddr <=
526 			  totalLogCapacity);
527 		RF_ASSERT(raidPtr->regionInfo[i].parityStartAddr +
528 			  raidPtr->regionInfo[i].numSectorsParity <=
529 			  raidPtr->sectorsPerDisk);
530 		printf("Allocating %d bytes for region %d\n",
531 		       (int) (raidPtr->regionInfo[i].capacity *
532 			   sizeof(RF_DiskMap_t)), i);
533 		RF_Malloc(raidPtr->regionInfo[i].diskMap,
534 			  (raidPtr->regionInfo[i].capacity *
535 			   sizeof(RF_DiskMap_t)),
536 			  (RF_DiskMap_t *));
537 		if (raidPtr->regionInfo[i].diskMap == NULL) {
538 			rf_mutex_destroy(&raidPtr->regionInfo[i].mutex);
539 			rf_mutex_destroy(&raidPtr->regionInfo[i].reintMutex);
540 			for (j = 0; j < i; j++)
541 				FreeRegionInfo(raidPtr, j);
542 			RF_Free(raidPtr->regionInfo,
543 				(rf_numParityRegions *
544 				 sizeof(RF_RegionInfo_t)));
545 			return (ENOMEM);
546 		}
547 		raidPtr->regionInfo[i].loggingEnabled = RF_FALSE;
548 		raidPtr->regionInfo[i].coreLog = NULL;
549 	}
550 	rc = rf_ShutdownCreate(listp,
551 			       rf_ShutdownParityLoggingRegionInfo,
552 			       raidPtr);
553 	if (rc) {
554 		RF_ERRORMSG3("Unable to create shutdown entry file %s line %d rc=%d\n", __FILE__,
555 		    __LINE__, rc);
556 		rf_ShutdownParityLoggingRegionInfo(raidPtr);
557 		return (rc);
558 	}
559 	RF_ASSERT(raidPtr->parityLogDiskQueue.threadState == 0);
560 	raidPtr->parityLogDiskQueue.threadState = RF_PLOG_CREATED;
561 	rc = RF_CREATE_THREAD(raidPtr->pLogDiskThreadHandle,
562 			      rf_ParityLoggingDiskManager, raidPtr,"rf_log");
563 	if (rc) {
564 		raidPtr->parityLogDiskQueue.threadState = 0;
565 		RF_ERRORMSG3("Unable to create parity logging disk thread file %s line %d rc=%d\n",
566 		    __FILE__, __LINE__, rc);
567 		return (ENOMEM);
568 	}
569 	/* wait for thread to start */
570 	RF_LOCK_MUTEX(raidPtr->parityLogDiskQueue.mutex);
571 	while (!(raidPtr->parityLogDiskQueue.threadState & RF_PLOG_RUNNING)) {
572 		RF_WAIT_COND(raidPtr->parityLogDiskQueue.cond,
573 			     raidPtr->parityLogDiskQueue.mutex);
574 	}
575 	RF_UNLOCK_MUTEX(raidPtr->parityLogDiskQueue.mutex);
576 
577 	rc = rf_ShutdownCreate(listp, rf_ShutdownParityLogging, raidPtr);
578 	if (rc) {
579 		RF_ERRORMSG1("Got rc=%d adding parity logging shutdown event\n", rc);
580 		rf_ShutdownParityLogging(raidPtr);
581 		return (rc);
582 	}
583 	if (rf_parityLogDebug) {
584 		printf("                            size of disk log in sectors: %d\n",
585 		    (int) totalLogCapacity);
586 		printf("                            total number of parity regions is %d\n", (int) rf_numParityRegions);
587 		printf("                            nominal sectors of log per parity region is %d\n", (int) raidPtr->regionLogCapacity);
588 		printf("                            nominal region fragmentation is %d sectors\n", (int) fragmentation);
589 		printf("                            total number of parity logs is %d\n", raidPtr->numParityLogs);
590 		printf("                            parity log size is %d sectors\n", raidPtr->numSectorsPerLog);
591 		printf("                            total in-core log space is %d bytes\n", (int) rf_totalInCoreLogCapacity);
592 	}
593 	rf_EnableParityLogging(raidPtr);
594 
595 	return (0);
596 }
597 
598 static void
599 FreeRegionInfo(
600     RF_Raid_t * raidPtr,
601     RF_RegionId_t regionID)
602 {
603 	RF_LOCK_MUTEX(raidPtr->regionInfo[regionID].mutex);
604 	RF_Free(raidPtr->regionInfo[regionID].diskMap,
605 		(raidPtr->regionInfo[regionID].capacity *
606 		 sizeof(RF_DiskMap_t)));
607 	if (!rf_forceParityLogReint && raidPtr->regionInfo[regionID].coreLog) {
608 		rf_ReleaseParityLogs(raidPtr,
609 				     raidPtr->regionInfo[regionID].coreLog);
610 		raidPtr->regionInfo[regionID].coreLog = NULL;
611 	} else {
612 		RF_ASSERT(raidPtr->regionInfo[regionID].coreLog == NULL);
613 		RF_ASSERT(raidPtr->regionInfo[regionID].diskCount == 0);
614 	}
615 	RF_UNLOCK_MUTEX(raidPtr->regionInfo[regionID].mutex);
616 	rf_mutex_destroy(&raidPtr->regionInfo[regionID].mutex);
617 	rf_mutex_destroy(&raidPtr->regionInfo[regionID].reintMutex);
618 }
619 
620 
621 static void
622 FreeParityLogQueue(
623     RF_Raid_t * raidPtr,
624     RF_ParityLogQueue_t * queue)
625 {
626 	RF_ParityLog_t *l1, *l2;
627 
628 	RF_LOCK_MUTEX(queue->mutex);
629 	l1 = queue->parityLogs;
630 	while (l1) {
631 		l2 = l1;
632 		l1 = l2->next;
633 		RF_Free(l2->records, (raidPtr->numSectorsPerLog *
634 				      sizeof(RF_ParityLogRecord_t)));
635 		RF_Free(l2, sizeof(RF_ParityLog_t));
636 	}
637 	RF_UNLOCK_MUTEX(queue->mutex);
638 	rf_mutex_destroy(&queue->mutex);
639 }
640 
641 
642 static void
643 FreeRegionBufferQueue(RF_RegionBufferQueue_t * queue)
644 {
645 	int     i;
646 
647 	RF_LOCK_MUTEX(queue->mutex);
648 	if (queue->availableBuffers != queue->totalBuffers) {
649 		printf("Attempt to free region queue which is still in use!\n");
650 		RF_ASSERT(0);
651 	}
652 	for (i = 0; i < queue->totalBuffers; i++)
653 		RF_Free(queue->buffers[i], queue->bufferSize);
654 	RF_Free(queue->buffers, queue->totalBuffers * sizeof(caddr_t));
655 	RF_UNLOCK_MUTEX(queue->mutex);
656 	rf_mutex_destroy(&queue->mutex);
657 }
658 
659 static void
660 rf_ShutdownParityLoggingRegionInfo(RF_ThreadArg_t arg)
661 {
662 	RF_Raid_t *raidPtr;
663 	RF_RegionId_t i;
664 
665 	raidPtr = (RF_Raid_t *) arg;
666 	if (rf_parityLogDebug) {
667 		printf("raid%d: ShutdownParityLoggingRegionInfo\n",
668 		       raidPtr->raidid);
669 	}
670 	/* free region information structs */
671 	for (i = 0; i < rf_numParityRegions; i++)
672 		FreeRegionInfo(raidPtr, i);
673 	RF_Free(raidPtr->regionInfo, (rf_numParityRegions *
674 				      sizeof(raidPtr->regionInfo)));
675 	raidPtr->regionInfo = NULL;
676 }
677 
678 static void
679 rf_ShutdownParityLoggingPool(RF_ThreadArg_t arg)
680 {
681 	RF_Raid_t *raidPtr;
682 
683 	raidPtr = (RF_Raid_t *) arg;
684 	if (rf_parityLogDebug) {
685 		printf("raid%d: ShutdownParityLoggingPool\n", raidPtr->raidid);
686 	}
687 	/* free contents of parityLogPool */
688 	FreeParityLogQueue(raidPtr, &raidPtr->parityLogPool);
689 	RF_Free(raidPtr->parityLogBufferHeap, raidPtr->numParityLogs *
690 		raidPtr->numSectorsPerLog * raidPtr->bytesPerSector);
691 }
692 
693 static void
694 rf_ShutdownParityLoggingRegionBufferPool(RF_ThreadArg_t arg)
695 {
696 	RF_Raid_t *raidPtr;
697 
698 	raidPtr = (RF_Raid_t *) arg;
699 	if (rf_parityLogDebug) {
700 		printf("raid%d: ShutdownParityLoggingRegionBufferPool\n",
701 		       raidPtr->raidid);
702 	}
703 	FreeRegionBufferQueue(&raidPtr->regionBufferPool);
704 }
705 
706 static void
707 rf_ShutdownParityLoggingParityBufferPool(RF_ThreadArg_t arg)
708 {
709 	RF_Raid_t *raidPtr;
710 
711 	raidPtr = (RF_Raid_t *) arg;
712 	if (rf_parityLogDebug) {
713 		printf("raid%d: ShutdownParityLoggingParityBufferPool\n",
714 		       raidPtr->raidid);
715 	}
716 	FreeRegionBufferQueue(&raidPtr->parityBufferPool);
717 }
718 
719 static void
720 rf_ShutdownParityLoggingDiskQueue(RF_ThreadArg_t arg)
721 {
722 	RF_ParityLogData_t *d;
723 	RF_CommonLogData_t *c;
724 	RF_Raid_t *raidPtr;
725 
726 	raidPtr = (RF_Raid_t *) arg;
727 	if (rf_parityLogDebug) {
728 		printf("raid%d: ShutdownParityLoggingDiskQueue\n",
729 		       raidPtr->raidid);
730 	}
731 	/* free disk manager stuff */
732 	RF_ASSERT(raidPtr->parityLogDiskQueue.bufHead == NULL);
733 	RF_ASSERT(raidPtr->parityLogDiskQueue.bufTail == NULL);
734 	RF_ASSERT(raidPtr->parityLogDiskQueue.reintHead == NULL);
735 	RF_ASSERT(raidPtr->parityLogDiskQueue.reintTail == NULL);
736 	while (raidPtr->parityLogDiskQueue.freeDataList) {
737 		d = raidPtr->parityLogDiskQueue.freeDataList;
738 		raidPtr->parityLogDiskQueue.freeDataList =
739 			raidPtr->parityLogDiskQueue.freeDataList->next;
740 		RF_Free(d, sizeof(RF_ParityLogData_t));
741 	}
742 	while (raidPtr->parityLogDiskQueue.freeCommonList) {
743 		c = raidPtr->parityLogDiskQueue.freeCommonList;
744 		rf_mutex_destroy(&c->mutex);
745 		raidPtr->parityLogDiskQueue.freeCommonList =
746 			raidPtr->parityLogDiskQueue.freeCommonList->next;
747 		RF_Free(c, sizeof(RF_CommonLogData_t));
748 	}
749 }
750 
751 static void
752 rf_ShutdownParityLogging(RF_ThreadArg_t arg)
753 {
754 	RF_Raid_t *raidPtr;
755 
756 	raidPtr = (RF_Raid_t *) arg;
757 	if (rf_parityLogDebug) {
758 		printf("raid%d: ShutdownParityLogging\n", raidPtr->raidid);
759 	}
760 	/* shutdown disk thread */
761 	/* This has the desirable side-effect of forcing all regions to be
762 	 * reintegrated.  This is necessary since all parity log maps are
763 	 * currently held in volatile memory. */
764 
765 	RF_LOCK_MUTEX(raidPtr->parityLogDiskQueue.mutex);
766 	raidPtr->parityLogDiskQueue.threadState |= RF_PLOG_TERMINATE;
767 	RF_UNLOCK_MUTEX(raidPtr->parityLogDiskQueue.mutex);
768 	RF_SIGNAL_COND(raidPtr->parityLogDiskQueue.cond);
769 	/*
770          * pLogDiskThread will now terminate when queues are cleared
771          * now wait for it to be done
772          */
773 	RF_LOCK_MUTEX(raidPtr->parityLogDiskQueue.mutex);
774 	while (!(raidPtr->parityLogDiskQueue.threadState & RF_PLOG_SHUTDOWN)) {
775 		RF_WAIT_COND(raidPtr->parityLogDiskQueue.cond,
776 			     raidPtr->parityLogDiskQueue.mutex);
777 	}
778 	RF_UNLOCK_MUTEX(raidPtr->parityLogDiskQueue.mutex);
779 	if (rf_parityLogDebug) {
780 		printf("raid%d: ShutdownParityLogging done (thread completed)\n", raidPtr->raidid);
781 	}
782 }
783 
784 int
785 rf_GetDefaultNumFloatingReconBuffersParityLogging(RF_Raid_t * raidPtr)
786 {
787 	return (20);
788 }
789 
790 RF_HeadSepLimit_t
791 rf_GetDefaultHeadSepLimitParityLogging(RF_Raid_t * raidPtr)
792 {
793 	return (10);
794 }
795 /* return the region ID for a given RAID address */
796 RF_RegionId_t
797 rf_MapRegionIDParityLogging(
798     RF_Raid_t * raidPtr,
799     RF_SectorNum_t address)
800 {
801 	RF_RegionId_t regionID;
802 
803 /*  regionID = address / (raidPtr->regionParityRange * raidPtr->Layout.numDataCol); */
804 	regionID = address / raidPtr->regionParityRange;
805 	if (regionID == rf_numParityRegions) {
806 		/* last region may be larger than other regions */
807 		regionID--;
808 	}
809 	RF_ASSERT(address >= raidPtr->regionInfo[regionID].parityStartAddr);
810 	RF_ASSERT(address < raidPtr->regionInfo[regionID].parityStartAddr +
811 		  raidPtr->regionInfo[regionID].numSectorsParity);
812 	RF_ASSERT(regionID < rf_numParityRegions);
813 	return (regionID);
814 }
815 
816 
817 /* given a logical RAID sector, determine physical disk address of data */
818 void
819 rf_MapSectorParityLogging(
820     RF_Raid_t * raidPtr,
821     RF_RaidAddr_t raidSector,
822     RF_RowCol_t * row,
823     RF_RowCol_t * col,
824     RF_SectorNum_t * diskSector,
825     int remap)
826 {
827 	RF_StripeNum_t SUID = raidSector /
828 		raidPtr->Layout.sectorsPerStripeUnit;
829 	*row = 0;
830 	/* *col = (SUID % (raidPtr->numCol -
831 	 * raidPtr->Layout.numParityLogCol)); */
832 	*col = SUID % raidPtr->Layout.numDataCol;
833 	*diskSector = (SUID / (raidPtr->Layout.numDataCol)) *
834 		raidPtr->Layout.sectorsPerStripeUnit +
835 		(raidSector % raidPtr->Layout.sectorsPerStripeUnit);
836 }
837 
838 
839 /* given a logical RAID sector, determine physical disk address of parity  */
840 void
841 rf_MapParityParityLogging(
842     RF_Raid_t * raidPtr,
843     RF_RaidAddr_t raidSector,
844     RF_RowCol_t * row,
845     RF_RowCol_t * col,
846     RF_SectorNum_t * diskSector,
847     int remap)
848 {
849 	RF_StripeNum_t SUID = raidSector /
850 		raidPtr->Layout.sectorsPerStripeUnit;
851 
852 	*row = 0;
853 	/* *col =
854 	 * raidPtr->Layout.numDataCol-(SUID/raidPtr->Layout.numDataCol)%(raidPt
855 	 * r->numCol - raidPtr->Layout.numParityLogCol); */
856 	*col = raidPtr->Layout.numDataCol;
857 	*diskSector = (SUID / (raidPtr->Layout.numDataCol)) *
858 		raidPtr->Layout.sectorsPerStripeUnit +
859 		(raidSector % raidPtr->Layout.sectorsPerStripeUnit);
860 }
861 
862 
863 /* given a regionID and sector offset, determine the physical disk address of the parity log */
864 void
865 rf_MapLogParityLogging(
866     RF_Raid_t * raidPtr,
867     RF_RegionId_t regionID,
868     RF_SectorNum_t regionOffset,
869     RF_RowCol_t * row,
870     RF_RowCol_t * col,
871     RF_SectorNum_t * startSector)
872 {
873 	*row = 0;
874 	*col = raidPtr->numCol - 1;
875 	*startSector = raidPtr->regionInfo[regionID].regionStartAddr + regionOffset;
876 }
877 
878 
879 /* given a regionID, determine the physical disk address of the logged
880    parity for that region */
881 void
882 rf_MapRegionParity(
883     RF_Raid_t * raidPtr,
884     RF_RegionId_t regionID,
885     RF_RowCol_t * row,
886     RF_RowCol_t * col,
887     RF_SectorNum_t * startSector,
888     RF_SectorCount_t * numSector)
889 {
890 	*row = 0;
891 	*col = raidPtr->numCol - 2;
892 	*startSector = raidPtr->regionInfo[regionID].parityStartAddr;
893 	*numSector = raidPtr->regionInfo[regionID].numSectorsParity;
894 }
895 
896 
897 /* given a logical RAID address, determine the participating disks in
898    the stripe */
899 void
900 rf_IdentifyStripeParityLogging(
901     RF_Raid_t * raidPtr,
902     RF_RaidAddr_t addr,
903     RF_RowCol_t ** diskids,
904     RF_RowCol_t * outRow)
905 {
906 	RF_StripeNum_t stripeID = rf_RaidAddressToStripeID(&raidPtr->Layout,
907 							   addr);
908 	RF_ParityLoggingConfigInfo_t *info = (RF_ParityLoggingConfigInfo_t *)
909 		raidPtr->Layout.layoutSpecificInfo;
910 	*outRow = 0;
911 	*diskids = info->stripeIdentifier[stripeID % raidPtr->numCol];
912 }
913 
914 
915 void
916 rf_MapSIDToPSIDParityLogging(
917     RF_RaidLayout_t * layoutPtr,
918     RF_StripeNum_t stripeID,
919     RF_StripeNum_t * psID,
920     RF_ReconUnitNum_t * which_ru)
921 {
922 	*which_ru = 0;
923 	*psID = stripeID;
924 }
925 
926 
927 /* select an algorithm for performing an access.  Returns two pointers,
928  * one to a function that will return information about the DAG, and
929  * another to a function that will create the dag.
930  */
931 void
932 rf_ParityLoggingDagSelect(
933     RF_Raid_t * raidPtr,
934     RF_IoType_t type,
935     RF_AccessStripeMap_t * asmp,
936     RF_VoidFuncPtr * createFunc)
937 {
938 	RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
939 	RF_PhysDiskAddr_t *failedPDA = NULL;
940 	RF_RowCol_t frow, fcol;
941 	RF_RowStatus_t rstat;
942 	int     prior_recon;
943 
944 	RF_ASSERT(RF_IO_IS_R_OR_W(type));
945 
946 	if (asmp->numDataFailed + asmp->numParityFailed > 1) {
947 		RF_ERRORMSG("Multiple disks failed in a single group!  Aborting I/O operation.\n");
948 		 /* *infoFunc = */ *createFunc = NULL;
949 		return;
950 	} else
951 		if (asmp->numDataFailed + asmp->numParityFailed == 1) {
952 
953 			/* if under recon & already reconstructed, redirect
954 			 * the access to the spare drive and eliminate the
955 			 * failure indication */
956 			failedPDA = asmp->failedPDAs[0];
957 			frow = failedPDA->row;
958 			fcol = failedPDA->col;
959 			rstat = raidPtr->status[failedPDA->row];
960 			prior_recon = (rstat == rf_rs_reconfigured) || (
961 			    (rstat == rf_rs_reconstructing) ?
962 			    rf_CheckRUReconstructed(raidPtr->reconControl[frow]->reconMap, failedPDA->startSector) : 0
963 			    );
964 			if (prior_recon) {
965 				RF_RowCol_t or = failedPDA->row, oc = failedPDA->col;
966 				RF_SectorNum_t oo = failedPDA->startSector;
967 				if (layoutPtr->map->flags &
968 				    RF_DISTRIBUTE_SPARE) {
969 					/* redirect to dist spare space */
970 
971 					if (failedPDA == asmp->parityInfo) {
972 
973 						/* parity has failed */
974 						(layoutPtr->map->MapParity) (raidPtr, failedPDA->raidAddress, &failedPDA->row,
975 						    &failedPDA->col, &failedPDA->startSector, RF_REMAP);
976 
977 						if (asmp->parityInfo->next) {	/* redir 2nd component,
978 										 * if any */
979 							RF_PhysDiskAddr_t *p = asmp->parityInfo->next;
980 							RF_SectorNum_t SUoffs = p->startSector % layoutPtr->sectorsPerStripeUnit;
981 							p->row = failedPDA->row;
982 							p->col = failedPDA->col;
983 							p->startSector = rf_RaidAddressOfPrevStripeUnitBoundary(layoutPtr, failedPDA->startSector) +
984 							    SUoffs;	/* cheating:
985 									 * startSector is not
986 									 * really a RAID address */
987 						}
988 					} else
989 						if (asmp->parityInfo->next && failedPDA == asmp->parityInfo->next) {
990 							RF_ASSERT(0);	/* should not ever
991 									 * happen */
992 						} else {
993 
994 							/* data has failed */
995 							(layoutPtr->map->MapSector) (raidPtr, failedPDA->raidAddress, &failedPDA->row,
996 							    &failedPDA->col, &failedPDA->startSector, RF_REMAP);
997 
998 						}
999 
1000 				} else {
1001 					/* redirect to dedicated spare space */
1002 
1003 					failedPDA->row = raidPtr->Disks[frow][fcol].spareRow;
1004 					failedPDA->col = raidPtr->Disks[frow][fcol].spareCol;
1005 
1006 					/* the parity may have two distinct
1007 					 * components, both of which may need
1008 					 * to be redirected */
1009 					if (asmp->parityInfo->next) {
1010 						if (failedPDA == asmp->parityInfo) {
1011 							failedPDA->next->row = failedPDA->row;
1012 							failedPDA->next->col = failedPDA->col;
1013 						} else
1014 							if (failedPDA == asmp->parityInfo->next) {	/* paranoid:  should never occur */
1015 								asmp->parityInfo->row = failedPDA->row;
1016 								asmp->parityInfo->col = failedPDA->col;
1017 							}
1018 					}
1019 				}
1020 
1021 				RF_ASSERT(failedPDA->col != -1);
1022 
1023 				if (rf_dagDebug || rf_mapDebug) {
1024 					printf("raid%d: Redirected type '%c' r %d c %d o %ld -> r %d c %d o %ld\n",
1025 					    raidPtr->raidid, type, or, oc, (long) oo, failedPDA->row, failedPDA->col, (long) failedPDA->startSector);
1026 				}
1027 				asmp->numDataFailed = asmp->numParityFailed = 0;
1028 			}
1029 		}
1030 	if (type == RF_IO_TYPE_READ) {
1031 
1032 		if (asmp->numDataFailed == 0)
1033 			*createFunc = (RF_VoidFuncPtr) rf_CreateFaultFreeReadDAG;
1034 		else
1035 			*createFunc = (RF_VoidFuncPtr) rf_CreateRaidFiveDegradedReadDAG;
1036 
1037 	} else {
1038 
1039 
1040 		/* if mirroring, always use large writes.  If the access
1041 		 * requires two distinct parity updates, always do a small
1042 		 * write.  If the stripe contains a failure but the access
1043 		 * does not, do a small write. The first conditional
1044 		 * (numStripeUnitsAccessed <= numDataCol/2) uses a
1045 		 * less-than-or-equal rather than just a less-than because
1046 		 * when G is 3 or 4, numDataCol/2 is 1, and I want
1047 		 * single-stripe-unit updates to use just one disk. */
1048 		if ((asmp->numDataFailed + asmp->numParityFailed) == 0) {
1049 			if (((asmp->numStripeUnitsAccessed <=
1050 			      (layoutPtr->numDataCol / 2)) &&
1051 			     (layoutPtr->numDataCol != 1)) ||
1052 			    (asmp->parityInfo->next != NULL) ||
1053 			    rf_CheckStripeForFailures(raidPtr, asmp)) {
1054 				*createFunc = (RF_VoidFuncPtr) rf_CreateParityLoggingSmallWriteDAG;
1055 			} else
1056 				*createFunc = (RF_VoidFuncPtr) rf_CreateParityLoggingLargeWriteDAG;
1057 		} else
1058 			if (asmp->numParityFailed == 1)
1059 				*createFunc = (RF_VoidFuncPtr) rf_CreateNonRedundantWriteDAG;
1060 			else
1061 				if (asmp->numStripeUnitsAccessed != 1 && failedPDA->numSector != layoutPtr->sectorsPerStripeUnit)
1062 					*createFunc = NULL;
1063 				else
1064 					*createFunc = (RF_VoidFuncPtr) rf_CreateDegradedWriteDAG;
1065 	}
1066 }
1067 #endif				/* RF_INCLUDE_PARITYLOGGING > 0 */
1068