xref: /netbsd-src/sys/dev/raidframe/rf_reconstruct.c (revision 5aefcfdc06931dd97e76246d2fe0302f7b3fe094)
1 /*	$NetBSD: rf_reconstruct.c,v 1.26 2000/06/04 02:05:13 oster Exp $	*/
2 /*
3  * Copyright (c) 1995 Carnegie-Mellon University.
4  * All rights reserved.
5  *
6  * Author: Mark Holland
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  * rf_reconstruct.c -- code to perform on-line reconstruction
32  *
33  ************************************************************/
34 
35 #include "rf_types.h"
36 #include <sys/time.h>
37 #include <sys/buf.h>
38 #include <sys/errno.h>
39 
40 #include <sys/types.h>
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/proc.h>
44 #include <sys/ioctl.h>
45 #include <sys/fcntl.h>
46 #include <sys/vnode.h>
47 
48 
49 #include "rf_raid.h"
50 #include "rf_reconutil.h"
51 #include "rf_revent.h"
52 #include "rf_reconbuffer.h"
53 #include "rf_acctrace.h"
54 #include "rf_etimer.h"
55 #include "rf_dag.h"
56 #include "rf_desc.h"
57 #include "rf_general.h"
58 #include "rf_freelist.h"
59 #include "rf_debugprint.h"
60 #include "rf_driver.h"
61 #include "rf_utils.h"
62 #include "rf_shutdown.h"
63 
64 #include "rf_kintf.h"
65 
66 /* setting these to -1 causes them to be set to their default values if not set by debug options */
67 
68 #define Dprintf(s)         if (rf_reconDebug) rf_debug_printf(s,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL)
69 #define Dprintf1(s,a)         if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),NULL,NULL,NULL,NULL,NULL,NULL,NULL)
70 #define Dprintf2(s,a,b)       if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),NULL,NULL,NULL,NULL,NULL,NULL)
71 #define Dprintf3(s,a,b,c)     if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),(void *)((unsigned long)c),NULL,NULL,NULL,NULL,NULL)
72 #define Dprintf4(s,a,b,c,d)   if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),(void *)((unsigned long)c),(void *)((unsigned long)d),NULL,NULL,NULL,NULL)
73 #define Dprintf5(s,a,b,c,d,e) if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),(void *)((unsigned long)c),(void *)((unsigned long)d),(void *)((unsigned long)e),NULL,NULL,NULL)
74 #define Dprintf6(s,a,b,c,d,e,f) if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),(void *)((unsigned long)c),(void *)((unsigned long)d),(void *)((unsigned long)e),(void *)((unsigned long)f),NULL,NULL)
75 #define Dprintf7(s,a,b,c,d,e,f,g) if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),(void *)((unsigned long)c),(void *)((unsigned long)d),(void *)((unsigned long)e),(void *)((unsigned long)f),(void *)((unsigned long)g),NULL)
76 
77 #define DDprintf1(s,a)         if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),NULL,NULL,NULL,NULL,NULL,NULL,NULL)
78 #define DDprintf2(s,a,b)       if (rf_reconDebug) rf_debug_printf(s,(void *)((unsigned long)a),(void *)((unsigned long)b),NULL,NULL,NULL,NULL,NULL,NULL)
79 
80 static RF_FreeList_t *rf_recond_freelist;
81 #define RF_MAX_FREE_RECOND  4
82 #define RF_RECOND_INC       1
83 
84 static RF_RaidReconDesc_t *
85 AllocRaidReconDesc(RF_Raid_t * raidPtr,
86     RF_RowCol_t row, RF_RowCol_t col, RF_RaidDisk_t * spareDiskPtr,
87     int numDisksDone, RF_RowCol_t srow, RF_RowCol_t scol);
88 static void FreeReconDesc(RF_RaidReconDesc_t * reconDesc);
89 static int
90 ProcessReconEvent(RF_Raid_t * raidPtr, RF_RowCol_t frow,
91     RF_ReconEvent_t * event);
92 static int
93 IssueNextReadRequest(RF_Raid_t * raidPtr, RF_RowCol_t row,
94     RF_RowCol_t col);
95 static int TryToRead(RF_Raid_t * raidPtr, RF_RowCol_t row, RF_RowCol_t col);
96 static int
97 ComputePSDiskOffsets(RF_Raid_t * raidPtr, RF_StripeNum_t psid,
98     RF_RowCol_t row, RF_RowCol_t col, RF_SectorNum_t * outDiskOffset,
99     RF_SectorNum_t * outFailedDiskSectorOffset, RF_RowCol_t * spRow,
100     RF_RowCol_t * spCol, RF_SectorNum_t * spOffset);
101 static int IssueNextWriteRequest(RF_Raid_t * raidPtr, RF_RowCol_t row);
102 static int ReconReadDoneProc(void *arg, int status);
103 static int ReconWriteDoneProc(void *arg, int status);
104 static void
105 CheckForNewMinHeadSep(RF_Raid_t * raidPtr, RF_RowCol_t row,
106     RF_HeadSepLimit_t hsCtr);
107 static int
108 CheckHeadSeparation(RF_Raid_t * raidPtr, RF_PerDiskReconCtrl_t * ctrl,
109     RF_RowCol_t row, RF_RowCol_t col, RF_HeadSepLimit_t hsCtr,
110     RF_ReconUnitNum_t which_ru);
111 static int
112 CheckForcedOrBlockedReconstruction(RF_Raid_t * raidPtr,
113     RF_ReconParityStripeStatus_t * pssPtr, RF_PerDiskReconCtrl_t * ctrl,
114     RF_RowCol_t row, RF_RowCol_t col, RF_StripeNum_t psid,
115     RF_ReconUnitNum_t which_ru);
116 static void ForceReconReadDoneProc(void *arg, int status);
117 
118 static void rf_ShutdownReconstruction(void *);
119 
120 struct RF_ReconDoneProc_s {
121 	void    (*proc) (RF_Raid_t *, void *);
122 	void   *arg;
123 	RF_ReconDoneProc_t *next;
124 };
125 
126 static RF_FreeList_t *rf_rdp_freelist;
127 #define RF_MAX_FREE_RDP 4
128 #define RF_RDP_INC      1
129 
130 static void
131 SignalReconDone(RF_Raid_t * raidPtr)
132 {
133 	RF_ReconDoneProc_t *p;
134 
135 	RF_LOCK_MUTEX(raidPtr->recon_done_proc_mutex);
136 	for (p = raidPtr->recon_done_procs; p; p = p->next) {
137 		p->proc(raidPtr, p->arg);
138 	}
139 	RF_UNLOCK_MUTEX(raidPtr->recon_done_proc_mutex);
140 }
141 
142 int
143 rf_RegisterReconDoneProc(
144     RF_Raid_t * raidPtr,
145     void (*proc) (RF_Raid_t *, void *),
146     void *arg,
147     RF_ReconDoneProc_t ** handlep)
148 {
149 	RF_ReconDoneProc_t *p;
150 
151 	RF_FREELIST_GET(rf_rdp_freelist, p, next, (RF_ReconDoneProc_t *));
152 	if (p == NULL)
153 		return (ENOMEM);
154 	p->proc = proc;
155 	p->arg = arg;
156 	RF_LOCK_MUTEX(raidPtr->recon_done_proc_mutex);
157 	p->next = raidPtr->recon_done_procs;
158 	raidPtr->recon_done_procs = p;
159 	RF_UNLOCK_MUTEX(raidPtr->recon_done_proc_mutex);
160 	if (handlep)
161 		*handlep = p;
162 	return (0);
163 }
164 /**************************************************************************
165  *
166  * sets up the parameters that will be used by the reconstruction process
167  * currently there are none, except for those that the layout-specific
168  * configuration (e.g. rf_ConfigureDeclustered) routine sets up.
169  *
170  * in the kernel, we fire off the recon thread.
171  *
172  **************************************************************************/
173 static void
174 rf_ShutdownReconstruction(ignored)
175 	void   *ignored;
176 {
177 	RF_FREELIST_DESTROY(rf_recond_freelist, next, (RF_RaidReconDesc_t *));
178 	RF_FREELIST_DESTROY(rf_rdp_freelist, next, (RF_ReconDoneProc_t *));
179 }
180 
181 int
182 rf_ConfigureReconstruction(listp)
183 	RF_ShutdownList_t **listp;
184 {
185 	int     rc;
186 
187 	RF_FREELIST_CREATE(rf_recond_freelist, RF_MAX_FREE_RECOND,
188 	    RF_RECOND_INC, sizeof(RF_RaidReconDesc_t));
189 	if (rf_recond_freelist == NULL)
190 		return (ENOMEM);
191 	RF_FREELIST_CREATE(rf_rdp_freelist, RF_MAX_FREE_RDP,
192 	    RF_RDP_INC, sizeof(RF_ReconDoneProc_t));
193 	if (rf_rdp_freelist == NULL) {
194 		RF_FREELIST_DESTROY(rf_recond_freelist, next, (RF_RaidReconDesc_t *));
195 		return (ENOMEM);
196 	}
197 	rc = rf_ShutdownCreate(listp, rf_ShutdownReconstruction, NULL);
198 	if (rc) {
199 		RF_ERRORMSG3("Unable to add to shutdown list file %s line %d rc=%d\n",
200 		    __FILE__, __LINE__, rc);
201 		rf_ShutdownReconstruction(NULL);
202 		return (rc);
203 	}
204 	return (0);
205 }
206 
207 static RF_RaidReconDesc_t *
208 AllocRaidReconDesc(raidPtr, row, col, spareDiskPtr, numDisksDone, srow, scol)
209 	RF_Raid_t *raidPtr;
210 	RF_RowCol_t row;
211 	RF_RowCol_t col;
212 	RF_RaidDisk_t *spareDiskPtr;
213 	int     numDisksDone;
214 	RF_RowCol_t srow;
215 	RF_RowCol_t scol;
216 {
217 
218 	RF_RaidReconDesc_t *reconDesc;
219 
220 	RF_FREELIST_GET(rf_recond_freelist, reconDesc, next, (RF_RaidReconDesc_t *));
221 
222 	reconDesc->raidPtr = raidPtr;
223 	reconDesc->row = row;
224 	reconDesc->col = col;
225 	reconDesc->spareDiskPtr = spareDiskPtr;
226 	reconDesc->numDisksDone = numDisksDone;
227 	reconDesc->srow = srow;
228 	reconDesc->scol = scol;
229 	reconDesc->state = 0;
230 	reconDesc->next = NULL;
231 
232 	return (reconDesc);
233 }
234 
235 static void
236 FreeReconDesc(reconDesc)
237 	RF_RaidReconDesc_t *reconDesc;
238 {
239 #if RF_RECON_STATS > 0
240 	printf("RAIDframe: %lu recon event waits, %lu recon delays\n",
241 	    (long) reconDesc->numReconEventWaits, (long) reconDesc->numReconExecDelays);
242 #endif				/* RF_RECON_STATS > 0 */
243 	printf("RAIDframe: %lu max exec ticks\n",
244 	    (long) reconDesc->maxReconExecTicks);
245 #if (RF_RECON_STATS > 0) || defined(KERNEL)
246 	printf("\n");
247 #endif				/* (RF_RECON_STATS > 0) || KERNEL */
248 	RF_FREELIST_FREE(rf_recond_freelist, reconDesc, next);
249 }
250 
251 
252 /*****************************************************************************
253  *
254  * primary routine to reconstruct a failed disk.  This should be called from
255  * within its own thread.  It won't return until reconstruction completes,
256  * fails, or is aborted.
257  *****************************************************************************/
258 int
259 rf_ReconstructFailedDisk(raidPtr, row, col)
260 	RF_Raid_t *raidPtr;
261 	RF_RowCol_t row;
262 	RF_RowCol_t col;
263 {
264 	RF_LayoutSW_t *lp;
265 	int     rc;
266 
267 	lp = raidPtr->Layout.map;
268 	if (lp->SubmitReconBuffer) {
269 		/*
270 	         * The current infrastructure only supports reconstructing one
271 	         * disk at a time for each array.
272 	         */
273 		RF_LOCK_MUTEX(raidPtr->mutex);
274 		while (raidPtr->reconInProgress) {
275 			RF_WAIT_COND(raidPtr->waitForReconCond, raidPtr->mutex);
276 		}
277 		raidPtr->reconInProgress++;
278 		RF_UNLOCK_MUTEX(raidPtr->mutex);
279 		rc = rf_ReconstructFailedDiskBasic(raidPtr, row, col);
280 		RF_LOCK_MUTEX(raidPtr->mutex);
281 		raidPtr->reconInProgress--;
282 		RF_UNLOCK_MUTEX(raidPtr->mutex);
283 	} else {
284 		RF_ERRORMSG1("RECON: no way to reconstruct failed disk for arch %c\n",
285 		    lp->parityConfig);
286 		rc = EIO;
287 	}
288 	RF_SIGNAL_COND(raidPtr->waitForReconCond);
289 	wakeup(&raidPtr->waitForReconCond);	/* XXX Methinks this will be
290 						 * needed at some point... GO */
291 	return (rc);
292 }
293 
294 int
295 rf_ReconstructFailedDiskBasic(raidPtr, row, col)
296 	RF_Raid_t *raidPtr;
297 	RF_RowCol_t row;
298 	RF_RowCol_t col;
299 {
300 	RF_ComponentLabel_t c_label;
301 	RF_RaidDisk_t *spareDiskPtr = NULL;
302 	RF_RaidReconDesc_t *reconDesc;
303 	RF_RowCol_t srow, scol;
304 	int     numDisksDone = 0, rc;
305 
306 	/* first look for a spare drive onto which to reconstruct the data */
307 	/* spare disk descriptors are stored in row 0.  This may have to
308 	 * change eventually */
309 
310 	RF_LOCK_MUTEX(raidPtr->mutex);
311 	RF_ASSERT(raidPtr->Disks[row][col].status == rf_ds_failed);
312 
313 	if (raidPtr->Layout.map->flags & RF_DISTRIBUTE_SPARE) {
314 		if (raidPtr->status[row] != rf_rs_degraded) {
315 			RF_ERRORMSG2("Unable to reconstruct disk at row %d col %d because status not degraded\n", row, col);
316 			RF_UNLOCK_MUTEX(raidPtr->mutex);
317 			return (EINVAL);
318 		}
319 		srow = row;
320 		scol = (-1);
321 	} else {
322 		srow = 0;
323 		for (scol = raidPtr->numCol; scol < raidPtr->numCol + raidPtr->numSpare; scol++) {
324 			if (raidPtr->Disks[srow][scol].status == rf_ds_spare) {
325 				spareDiskPtr = &raidPtr->Disks[srow][scol];
326 				spareDiskPtr->status = rf_ds_used_spare;
327 				break;
328 			}
329 		}
330 		if (!spareDiskPtr) {
331 			RF_ERRORMSG2("Unable to reconstruct disk at row %d col %d because no spares are available\n", row, col);
332 			RF_UNLOCK_MUTEX(raidPtr->mutex);
333 			return (ENOSPC);
334 		}
335 		printf("RECON: initiating reconstruction on row %d col %d -> spare at row %d col %d\n", row, col, srow, scol);
336 	}
337 	RF_UNLOCK_MUTEX(raidPtr->mutex);
338 
339 	reconDesc = AllocRaidReconDesc((void *) raidPtr, row, col, spareDiskPtr, numDisksDone, srow, scol);
340 	raidPtr->reconDesc = (void *) reconDesc;
341 #if RF_RECON_STATS > 0
342 	reconDesc->hsStallCount = 0;
343 	reconDesc->numReconExecDelays = 0;
344 	reconDesc->numReconEventWaits = 0;
345 #endif				/* RF_RECON_STATS > 0 */
346 	reconDesc->reconExecTimerRunning = 0;
347 	reconDesc->reconExecTicks = 0;
348 	reconDesc->maxReconExecTicks = 0;
349 	rc = rf_ContinueReconstructFailedDisk(reconDesc);
350 
351 	if (!rc) {
352 		/* fix up the component label */
353 		/* Don't actually need the read here.. */
354 		raidread_component_label(
355                         raidPtr->raid_cinfo[srow][scol].ci_dev,
356 			raidPtr->raid_cinfo[srow][scol].ci_vp,
357 			&c_label);
358 
359 		raid_init_component_label( raidPtr, &c_label);
360 		c_label.row = row;
361 		c_label.column = col;
362 		c_label.clean = RF_RAID_DIRTY;
363 		c_label.status = rf_ds_optimal;
364 
365 		/* XXXX MORE NEEDED HERE */
366 
367 		raidwrite_component_label(
368                         raidPtr->raid_cinfo[srow][scol].ci_dev,
369 			raidPtr->raid_cinfo[srow][scol].ci_vp,
370 			&c_label);
371 
372 	}
373 	return (rc);
374 }
375 
376 /*
377 
378    Allow reconstructing a disk in-place -- i.e. component /dev/sd2e goes AWOL,
379    and you don't get a spare until the next Monday.  With this function
380    (and hot-swappable drives) you can now put your new disk containing
381    /dev/sd2e on the bus, scsictl it alive, and then use raidctl(8) to
382    rebuild the data "on the spot".
383 
384 */
385 
386 int
387 rf_ReconstructInPlace(raidPtr, row, col)
388 	RF_Raid_t *raidPtr;
389 	RF_RowCol_t row;
390 	RF_RowCol_t col;
391 {
392 	RF_RaidDisk_t *spareDiskPtr = NULL;
393 	RF_RaidReconDesc_t *reconDesc;
394 	RF_LayoutSW_t *lp;
395 	RF_RaidDisk_t *badDisk;
396 	RF_ComponentLabel_t c_label;
397 	int     numDisksDone = 0, rc;
398 	struct partinfo dpart;
399 	struct vnode *vp;
400 	struct vattr va;
401 	struct proc *proc;
402 	int retcode;
403 	int ac;
404 
405 	lp = raidPtr->Layout.map;
406 	if (lp->SubmitReconBuffer) {
407 		/*
408 	         * The current infrastructure only supports reconstructing one
409 	         * disk at a time for each array.
410 	         */
411 		RF_LOCK_MUTEX(raidPtr->mutex);
412 		if ((raidPtr->Disks[row][col].status == rf_ds_optimal) &&
413 		    (raidPtr->numFailures > 0)) {
414 			/* XXX 0 above shouldn't be constant!!! */
415 			/* some component other than this has failed.
416 			   Let's not make things worse than they already
417 			   are... */
418 			printf("RAIDFRAME: Unable to reconstruct to disk at:\n");
419 			printf("      Row: %d Col: %d   Too many failures.\n",
420 			       row, col);
421 			RF_UNLOCK_MUTEX(raidPtr->mutex);
422 			return (EINVAL);
423 		}
424 		if (raidPtr->Disks[row][col].status == rf_ds_reconstructing) {
425 			printf("RAIDFRAME: Unable to reconstruct to disk at:\n");
426 			printf("      Row: %d Col: %d   Reconstruction already occuring!\n", row, col);
427 
428 			RF_UNLOCK_MUTEX(raidPtr->mutex);
429 			return (EINVAL);
430 		}
431 
432 
433 		if (raidPtr->Disks[row][col].status != rf_ds_failed) {
434 			/* "It's gone..." */
435 			raidPtr->numFailures++;
436 			raidPtr->Disks[row][col].status = rf_ds_failed;
437 			raidPtr->status[row] = rf_rs_degraded;
438 			rf_update_component_labels(raidPtr,
439 						   RF_NORMAL_COMPONENT_UPDATE);
440 		}
441 
442 		while (raidPtr->reconInProgress) {
443 			RF_WAIT_COND(raidPtr->waitForReconCond, raidPtr->mutex);
444 		}
445 
446 		raidPtr->reconInProgress++;
447 
448 
449 		/* first look for a spare drive onto which to reconstruct
450 		   the data.  spare disk descriptors are stored in row 0.
451 		   This may have to change eventually */
452 
453 		/* Actually, we don't care if it's failed or not...
454 		   On a RAID set with correct parity, this function
455 		   should be callable on any component without ill affects. */
456 		/* RF_ASSERT(raidPtr->Disks[row][col].status == rf_ds_failed);
457 		 */
458 
459 		if (raidPtr->Layout.map->flags & RF_DISTRIBUTE_SPARE) {
460 			RF_ERRORMSG2("Unable to reconstruct to disk at row %d col %d: operation not supported for RF_DISTRIBUTE_SPARE\n", row, col);
461 
462 			raidPtr->reconInProgress--;
463 			RF_UNLOCK_MUTEX(raidPtr->mutex);
464 			return (EINVAL);
465 		}
466 
467 		/* XXX need goop here to see if the disk is alive,
468 		   and, if not, make it so...  */
469 
470 
471 
472 		badDisk = &raidPtr->Disks[row][col];
473 
474 		proc = raidPtr->engine_thread;
475 
476 		/* This device may have been opened successfully the
477 		   first time. Close it before trying to open it again.. */
478 
479 		if (raidPtr->raid_cinfo[row][col].ci_vp != NULL) {
480 			printf("Closed the open device: %s\n",
481 			       raidPtr->Disks[row][col].devname);
482 			vp = raidPtr->raid_cinfo[row][col].ci_vp;
483 			ac = raidPtr->Disks[row][col].auto_configured;
484 			rf_close_component(raidPtr, vp, ac);
485 			raidPtr->raid_cinfo[row][col].ci_vp = NULL;
486 		}
487 		/* note that this disk was *not* auto_configured (any longer)*/
488 		raidPtr->Disks[row][col].auto_configured = 0;
489 
490 		printf("About to (re-)open the device for rebuilding: %s\n",
491 		       raidPtr->Disks[row][col].devname);
492 
493 		retcode = raidlookup(raidPtr->Disks[row][col].devname,
494 				     proc, &vp);
495 
496 		if (retcode) {
497 			printf("raid%d: rebuilding: raidlookup on device: %s failed: %d!\n",raidPtr->raidid,
498 			       raidPtr->Disks[row][col].devname, retcode);
499 
500 			/* XXX the component isn't responding properly...
501 			   must be still dead :-( */
502 			raidPtr->reconInProgress--;
503 			RF_UNLOCK_MUTEX(raidPtr->mutex);
504 			return(retcode);
505 
506 		} else {
507 
508 			/* Ok, so we can at least do a lookup...
509 			   How about actually getting a vp for it? */
510 
511 			if ((retcode = VOP_GETATTR(vp, &va, proc->p_ucred,
512 						   proc)) != 0) {
513 				raidPtr->reconInProgress--;
514 				RF_UNLOCK_MUTEX(raidPtr->mutex);
515 				return(retcode);
516 			}
517 			retcode = VOP_IOCTL(vp, DIOCGPART, (caddr_t) & dpart,
518 					    FREAD, proc->p_ucred, proc);
519 			if (retcode) {
520 				raidPtr->reconInProgress--;
521 				RF_UNLOCK_MUTEX(raidPtr->mutex);
522 				return(retcode);
523 			}
524 			raidPtr->Disks[row][col].blockSize =
525 				dpart.disklab->d_secsize;
526 
527 			raidPtr->Disks[row][col].numBlocks =
528 				dpart.part->p_size - rf_protectedSectors;
529 
530 			raidPtr->raid_cinfo[row][col].ci_vp = vp;
531 			raidPtr->raid_cinfo[row][col].ci_dev = va.va_rdev;
532 
533 			raidPtr->Disks[row][col].dev = va.va_rdev;
534 
535 			/* we allow the user to specify that only a
536 			   fraction of the disks should be used this is
537 			   just for debug:  it speeds up
538 			 * the parity scan */
539 			raidPtr->Disks[row][col].numBlocks =
540 				raidPtr->Disks[row][col].numBlocks *
541 				rf_sizePercentage / 100;
542 		}
543 
544 
545 
546 		spareDiskPtr = &raidPtr->Disks[row][col];
547 		spareDiskPtr->status = rf_ds_used_spare;
548 
549 		printf("RECON: initiating in-place reconstruction on\n");
550 		printf("       row %d col %d -> spare at row %d col %d\n",
551 		       row, col, row, col);
552 
553 		RF_UNLOCK_MUTEX(raidPtr->mutex);
554 
555 		reconDesc = AllocRaidReconDesc((void *) raidPtr, row, col,
556 					       spareDiskPtr, numDisksDone,
557 					       row, col);
558 		raidPtr->reconDesc = (void *) reconDesc;
559 #if RF_RECON_STATS > 0
560 		reconDesc->hsStallCount = 0;
561 		reconDesc->numReconExecDelays = 0;
562 		reconDesc->numReconEventWaits = 0;
563 #endif				/* RF_RECON_STATS > 0 */
564 		reconDesc->reconExecTimerRunning = 0;
565 		reconDesc->reconExecTicks = 0;
566 		reconDesc->maxReconExecTicks = 0;
567 		rc = rf_ContinueReconstructFailedDisk(reconDesc);
568 
569 		RF_LOCK_MUTEX(raidPtr->mutex);
570 		raidPtr->reconInProgress--;
571 		RF_UNLOCK_MUTEX(raidPtr->mutex);
572 
573 	} else {
574 		RF_ERRORMSG1("RECON: no way to reconstruct failed disk for arch %c\n",
575 			     lp->parityConfig);
576 		rc = EIO;
577 	}
578 	RF_LOCK_MUTEX(raidPtr->mutex);
579 
580 	if (!rc) {
581 		/* Need to set these here, as at this point it'll be claiming
582 		   that the disk is in rf_ds_spared!  But we know better :-) */
583 
584 		raidPtr->Disks[row][col].status = rf_ds_optimal;
585 		raidPtr->status[row] = rf_rs_optimal;
586 
587 		/* fix up the component label */
588 		/* Don't actually need the read here.. */
589 		raidread_component_label(raidPtr->raid_cinfo[row][col].ci_dev,
590 					 raidPtr->raid_cinfo[row][col].ci_vp,
591 					 &c_label);
592 
593 		raid_init_component_label(raidPtr, &c_label);
594 
595 		c_label.row = row;
596 		c_label.column = col;
597 
598 		raidwrite_component_label(raidPtr->raid_cinfo[row][col].ci_dev,
599 					  raidPtr->raid_cinfo[row][col].ci_vp,
600 					  &c_label);
601 
602 	}
603 	RF_UNLOCK_MUTEX(raidPtr->mutex);
604 	RF_SIGNAL_COND(raidPtr->waitForReconCond);
605 	wakeup(&raidPtr->waitForReconCond);
606 	return (rc);
607 }
608 
609 
610 int
611 rf_ContinueReconstructFailedDisk(reconDesc)
612 	RF_RaidReconDesc_t *reconDesc;
613 {
614 	RF_Raid_t *raidPtr = reconDesc->raidPtr;
615 	RF_RowCol_t row = reconDesc->row;
616 	RF_RowCol_t col = reconDesc->col;
617 	RF_RowCol_t srow = reconDesc->srow;
618 	RF_RowCol_t scol = reconDesc->scol;
619 	RF_ReconMap_t *mapPtr;
620 
621 	RF_ReconEvent_t *event;
622 	struct timeval etime, elpsd;
623 	unsigned long xor_s, xor_resid_us;
624 	int     retcode, i, ds;
625 
626 	switch (reconDesc->state) {
627 
628 
629 	case 0:
630 
631 		raidPtr->accumXorTimeUs = 0;
632 
633 		/* create one trace record per physical disk */
634 		RF_Malloc(raidPtr->recon_tracerecs, raidPtr->numCol * sizeof(RF_AccTraceEntry_t), (RF_AccTraceEntry_t *));
635 
636 		/* quiesce the array prior to starting recon.  this is needed
637 		 * to assure no nasty interactions with pending user writes.
638 		 * We need to do this before we change the disk or row status. */
639 		reconDesc->state = 1;
640 
641 		Dprintf("RECON: begin request suspend\n");
642 		retcode = rf_SuspendNewRequestsAndWait(raidPtr);
643 		Dprintf("RECON: end request suspend\n");
644 		rf_StartUserStats(raidPtr);	/* zero out the stats kept on
645 						 * user accs */
646 
647 		/* fall through to state 1 */
648 
649 	case 1:
650 
651 		RF_LOCK_MUTEX(raidPtr->mutex);
652 
653 		/* create the reconstruction control pointer and install it in
654 		 * the right slot */
655 		raidPtr->reconControl[row] = rf_MakeReconControl(reconDesc, row, col, srow, scol);
656 		mapPtr = raidPtr->reconControl[row]->reconMap;
657 		raidPtr->status[row] = rf_rs_reconstructing;
658 		raidPtr->Disks[row][col].status = rf_ds_reconstructing;
659 		raidPtr->Disks[row][col].spareRow = srow;
660 		raidPtr->Disks[row][col].spareCol = scol;
661 
662 		RF_UNLOCK_MUTEX(raidPtr->mutex);
663 
664 		RF_GETTIME(raidPtr->reconControl[row]->starttime);
665 
666 		/* now start up the actual reconstruction: issue a read for
667 		 * each surviving disk */
668 
669 		reconDesc->numDisksDone = 0;
670 		for (i = 0; i < raidPtr->numCol; i++) {
671 			if (i != col) {
672 				/* find and issue the next I/O on the
673 				 * indicated disk */
674 				if (IssueNextReadRequest(raidPtr, row, i)) {
675 					Dprintf2("RECON: done issuing for r%d c%d\n", row, i);
676 					reconDesc->numDisksDone++;
677 				}
678 			}
679 		}
680 
681 	case 2:
682 		Dprintf("RECON: resume requests\n");
683 		rf_ResumeNewRequests(raidPtr);
684 
685 
686 		reconDesc->state = 3;
687 
688 	case 3:
689 
690 		/* process reconstruction events until all disks report that
691 		 * they've completed all work */
692 		mapPtr = raidPtr->reconControl[row]->reconMap;
693 
694 
695 
696 		while (reconDesc->numDisksDone < raidPtr->numCol - 1) {
697 
698 			event = rf_GetNextReconEvent(reconDesc, row, (void (*) (void *)) rf_ContinueReconstructFailedDisk, reconDesc);
699 			RF_ASSERT(event);
700 
701 			if (ProcessReconEvent(raidPtr, row, event))
702 				reconDesc->numDisksDone++;
703 			raidPtr->reconControl[row]->numRUsTotal =
704 				mapPtr->totalRUs;
705 			raidPtr->reconControl[row]->numRUsComplete =
706 				mapPtr->totalRUs -
707 				rf_UnitsLeftToReconstruct(mapPtr);
708 
709 			raidPtr->reconControl[row]->percentComplete =
710 				(raidPtr->reconControl[row]->numRUsComplete * 100 / raidPtr->reconControl[row]->numRUsTotal);
711 			if (rf_prReconSched) {
712 				rf_PrintReconSchedule(raidPtr->reconControl[row]->reconMap, &(raidPtr->reconControl[row]->starttime));
713 			}
714 		}
715 
716 
717 
718 		reconDesc->state = 4;
719 
720 
721 	case 4:
722 		mapPtr = raidPtr->reconControl[row]->reconMap;
723 		if (rf_reconDebug) {
724 			printf("RECON: all reads completed\n");
725 		}
726 		/* at this point all the reads have completed.  We now wait
727 		 * for any pending writes to complete, and then we're done */
728 
729 		while (rf_UnitsLeftToReconstruct(raidPtr->reconControl[row]->reconMap) > 0) {
730 
731 			event = rf_GetNextReconEvent(reconDesc, row, (void (*) (void *)) rf_ContinueReconstructFailedDisk, reconDesc);
732 			RF_ASSERT(event);
733 
734 			(void) ProcessReconEvent(raidPtr, row, event);	/* ignore return code */
735 			raidPtr->reconControl[row]->percentComplete = 100 - (rf_UnitsLeftToReconstruct(mapPtr) * 100 / mapPtr->totalRUs);
736 			if (rf_prReconSched) {
737 				rf_PrintReconSchedule(raidPtr->reconControl[row]->reconMap, &(raidPtr->reconControl[row]->starttime));
738 			}
739 		}
740 		reconDesc->state = 5;
741 
742 	case 5:
743 		/* Success:  mark the dead disk as reconstructed.  We quiesce
744 		 * the array here to assure no nasty interactions with pending
745 		 * user accesses when we free up the psstatus structure as
746 		 * part of FreeReconControl() */
747 
748 		reconDesc->state = 6;
749 
750 		retcode = rf_SuspendNewRequestsAndWait(raidPtr);
751 		rf_StopUserStats(raidPtr);
752 		rf_PrintUserStats(raidPtr);	/* print out the stats on user
753 						 * accs accumulated during
754 						 * recon */
755 
756 		/* fall through to state 6 */
757 	case 6:
758 
759 
760 
761 		RF_LOCK_MUTEX(raidPtr->mutex);
762 		raidPtr->numFailures--;
763 		ds = (raidPtr->Layout.map->flags & RF_DISTRIBUTE_SPARE);
764 		raidPtr->Disks[row][col].status = (ds) ? rf_ds_dist_spared : rf_ds_spared;
765 		raidPtr->status[row] = (ds) ? rf_rs_reconfigured : rf_rs_optimal;
766 		RF_UNLOCK_MUTEX(raidPtr->mutex);
767 		RF_GETTIME(etime);
768 		RF_TIMEVAL_DIFF(&(raidPtr->reconControl[row]->starttime), &etime, &elpsd);
769 
770 		/* XXX -- why is state 7 different from state 6 if there is no
771 		 * return() here? -- XXX Note that I set elpsd above & use it
772 		 * below, so if you put a return here you'll have to fix this.
773 		 * (also, FreeReconControl is called below) */
774 
775 	case 7:
776 
777 		rf_ResumeNewRequests(raidPtr);
778 
779 		printf("Reconstruction of disk at row %d col %d completed\n",
780 		       row, col);
781 		xor_s = raidPtr->accumXorTimeUs / 1000000;
782 		xor_resid_us = raidPtr->accumXorTimeUs % 1000000;
783 		printf("Recon time was %d.%06d seconds, accumulated XOR time was %ld us (%ld.%06ld)\n",
784 		    (int) elpsd.tv_sec, (int) elpsd.tv_usec, raidPtr->accumXorTimeUs, xor_s, xor_resid_us);
785 		printf("  (start time %d sec %d usec, end time %d sec %d usec)\n",
786 		    (int) raidPtr->reconControl[row]->starttime.tv_sec,
787 		    (int) raidPtr->reconControl[row]->starttime.tv_usec,
788 		    (int) etime.tv_sec, (int) etime.tv_usec);
789 
790 #if RF_RECON_STATS > 0
791 		printf("Total head-sep stall count was %d\n",
792 		    (int) reconDesc->hsStallCount);
793 #endif				/* RF_RECON_STATS > 0 */
794 		rf_FreeReconControl(raidPtr, row);
795 		RF_Free(raidPtr->recon_tracerecs, raidPtr->numCol * sizeof(RF_AccTraceEntry_t));
796 		FreeReconDesc(reconDesc);
797 
798 	}
799 
800 	SignalReconDone(raidPtr);
801 	return (0);
802 }
803 /*****************************************************************************
804  * do the right thing upon each reconstruction event.
805  * returns nonzero if and only if there is nothing left unread on the
806  * indicated disk
807  *****************************************************************************/
808 static int
809 ProcessReconEvent(raidPtr, frow, event)
810 	RF_Raid_t *raidPtr;
811 	RF_RowCol_t frow;
812 	RF_ReconEvent_t *event;
813 {
814 	int     retcode = 0, submitblocked;
815 	RF_ReconBuffer_t *rbuf;
816 	RF_SectorCount_t sectorsPerRU;
817 
818 	Dprintf1("RECON: ProcessReconEvent type %d\n", event->type);
819 	switch (event->type) {
820 
821 		/* a read I/O has completed */
822 	case RF_REVENT_READDONE:
823 		rbuf = raidPtr->reconControl[frow]->perDiskInfo[event->col].rbuf;
824 		Dprintf3("RECON: READDONE EVENT: row %d col %d psid %ld\n",
825 		    frow, event->col, rbuf->parityStripeID);
826 		Dprintf7("RECON: done read  psid %ld buf %lx  %02x %02x %02x %02x %02x\n",
827 		    rbuf->parityStripeID, rbuf->buffer, rbuf->buffer[0] & 0xff, rbuf->buffer[1] & 0xff,
828 		    rbuf->buffer[2] & 0xff, rbuf->buffer[3] & 0xff, rbuf->buffer[4] & 0xff);
829 		rf_FreeDiskQueueData((RF_DiskQueueData_t *) rbuf->arg);
830 		submitblocked = rf_SubmitReconBuffer(rbuf, 0, 0);
831 		Dprintf1("RECON: submitblocked=%d\n", submitblocked);
832 		if (!submitblocked)
833 			retcode = IssueNextReadRequest(raidPtr, frow, event->col);
834 		break;
835 
836 		/* a write I/O has completed */
837 	case RF_REVENT_WRITEDONE:
838 		if (rf_floatingRbufDebug) {
839 			rf_CheckFloatingRbufCount(raidPtr, 1);
840 		}
841 		sectorsPerRU = raidPtr->Layout.sectorsPerStripeUnit * raidPtr->Layout.SUsPerRU;
842 		rbuf = (RF_ReconBuffer_t *) event->arg;
843 		rf_FreeDiskQueueData((RF_DiskQueueData_t *) rbuf->arg);
844 		Dprintf3("RECON: WRITEDONE EVENT: psid %d ru %d (%d %% complete)\n",
845 		    rbuf->parityStripeID, rbuf->which_ru, raidPtr->reconControl[frow]->percentComplete);
846 		rf_ReconMapUpdate(raidPtr, raidPtr->reconControl[frow]->reconMap,
847 		    rbuf->failedDiskSectorOffset, rbuf->failedDiskSectorOffset + sectorsPerRU - 1);
848 		rf_RemoveFromActiveReconTable(raidPtr, frow, rbuf->parityStripeID, rbuf->which_ru);
849 
850 		if (rbuf->type == RF_RBUF_TYPE_FLOATING) {
851 			RF_LOCK_MUTEX(raidPtr->reconControl[frow]->rb_mutex);
852 			raidPtr->numFullReconBuffers--;
853 			rf_ReleaseFloatingReconBuffer(raidPtr, frow, rbuf);
854 			RF_UNLOCK_MUTEX(raidPtr->reconControl[frow]->rb_mutex);
855 		} else
856 			if (rbuf->type == RF_RBUF_TYPE_FORCED)
857 				rf_FreeReconBuffer(rbuf);
858 			else
859 				RF_ASSERT(0);
860 		break;
861 
862 	case RF_REVENT_BUFCLEAR:	/* A buffer-stall condition has been
863 					 * cleared */
864 		Dprintf2("RECON: BUFCLEAR EVENT: row %d col %d\n", frow, event->col);
865 		submitblocked = rf_SubmitReconBuffer(raidPtr->reconControl[frow]->perDiskInfo[event->col].rbuf, 0, (int) (long) event->arg);
866 		RF_ASSERT(!submitblocked);	/* we wouldn't have gotten the
867 						 * BUFCLEAR event if we
868 						 * couldn't submit */
869 		retcode = IssueNextReadRequest(raidPtr, frow, event->col);
870 		break;
871 
872 	case RF_REVENT_BLOCKCLEAR:	/* A user-write reconstruction
873 					 * blockage has been cleared */
874 		DDprintf2("RECON: BLOCKCLEAR EVENT: row %d col %d\n", frow, event->col);
875 		retcode = TryToRead(raidPtr, frow, event->col);
876 		break;
877 
878 	case RF_REVENT_HEADSEPCLEAR:	/* A max-head-separation
879 					 * reconstruction blockage has been
880 					 * cleared */
881 		Dprintf2("RECON: HEADSEPCLEAR EVENT: row %d col %d\n", frow, event->col);
882 		retcode = TryToRead(raidPtr, frow, event->col);
883 		break;
884 
885 		/* a buffer has become ready to write */
886 	case RF_REVENT_BUFREADY:
887 		Dprintf2("RECON: BUFREADY EVENT: row %d col %d\n", frow, event->col);
888 		retcode = IssueNextWriteRequest(raidPtr, frow);
889 		if (rf_floatingRbufDebug) {
890 			rf_CheckFloatingRbufCount(raidPtr, 1);
891 		}
892 		break;
893 
894 		/* we need to skip the current RU entirely because it got
895 		 * recon'd while we were waiting for something else to happen */
896 	case RF_REVENT_SKIP:
897 		DDprintf2("RECON: SKIP EVENT: row %d col %d\n", frow, event->col);
898 		retcode = IssueNextReadRequest(raidPtr, frow, event->col);
899 		break;
900 
901 		/* a forced-reconstruction read access has completed.  Just
902 		 * submit the buffer */
903 	case RF_REVENT_FORCEDREADDONE:
904 		rbuf = (RF_ReconBuffer_t *) event->arg;
905 		rf_FreeDiskQueueData((RF_DiskQueueData_t *) rbuf->arg);
906 		DDprintf2("RECON: FORCEDREADDONE EVENT: row %d col %d\n", frow, event->col);
907 		submitblocked = rf_SubmitReconBuffer(rbuf, 1, 0);
908 		RF_ASSERT(!submitblocked);
909 		break;
910 
911 	default:
912 		RF_PANIC();
913 	}
914 	rf_FreeReconEventDesc(event);
915 	return (retcode);
916 }
917 /*****************************************************************************
918  *
919  * find the next thing that's needed on the indicated disk, and issue
920  * a read request for it.  We assume that the reconstruction buffer
921  * associated with this process is free to receive the data.  If
922  * reconstruction is blocked on the indicated RU, we issue a
923  * blockage-release request instead of a physical disk read request.
924  * If the current disk gets too far ahead of the others, we issue a
925  * head-separation wait request and return.
926  *
927  * ctrl->{ru_count, curPSID, diskOffset} and
928  * rbuf->failedDiskSectorOffset are maintained to point to the unit
929  * we're currently accessing.  Note that this deviates from the
930  * standard C idiom of having counters point to the next thing to be
931  * accessed.  This allows us to easily retry when we're blocked by
932  * head separation or reconstruction-blockage events.
933  *
934  * returns nonzero if and only if there is nothing left unread on the
935  * indicated disk
936  *
937  *****************************************************************************/
938 static int
939 IssueNextReadRequest(raidPtr, row, col)
940 	RF_Raid_t *raidPtr;
941 	RF_RowCol_t row;
942 	RF_RowCol_t col;
943 {
944 	RF_PerDiskReconCtrl_t *ctrl = &raidPtr->reconControl[row]->perDiskInfo[col];
945 	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
946 	RF_ReconBuffer_t *rbuf = ctrl->rbuf;
947 	RF_ReconUnitCount_t RUsPerPU = layoutPtr->SUsPerPU / layoutPtr->SUsPerRU;
948 	RF_SectorCount_t sectorsPerRU = layoutPtr->sectorsPerStripeUnit * layoutPtr->SUsPerRU;
949 	int     do_new_check = 0, retcode = 0, status;
950 
951 	/* if we are currently the slowest disk, mark that we have to do a new
952 	 * check */
953 	if (ctrl->headSepCounter <= raidPtr->reconControl[row]->minHeadSepCounter)
954 		do_new_check = 1;
955 
956 	while (1) {
957 
958 		ctrl->ru_count++;
959 		if (ctrl->ru_count < RUsPerPU) {
960 			ctrl->diskOffset += sectorsPerRU;
961 			rbuf->failedDiskSectorOffset += sectorsPerRU;
962 		} else {
963 			ctrl->curPSID++;
964 			ctrl->ru_count = 0;
965 			/* code left over from when head-sep was based on
966 			 * parity stripe id */
967 			if (ctrl->curPSID >= raidPtr->reconControl[row]->lastPSID) {
968 				CheckForNewMinHeadSep(raidPtr, row, ++(ctrl->headSepCounter));
969 				return (1);	/* finito! */
970 			}
971 			/* find the disk offsets of the start of the parity
972 			 * stripe on both the current disk and the failed
973 			 * disk. skip this entire parity stripe if either disk
974 			 * does not appear in the indicated PS */
975 			status = ComputePSDiskOffsets(raidPtr, ctrl->curPSID, row, col, &ctrl->diskOffset, &rbuf->failedDiskSectorOffset,
976 			    &rbuf->spRow, &rbuf->spCol, &rbuf->spOffset);
977 			if (status) {
978 				ctrl->ru_count = RUsPerPU - 1;
979 				continue;
980 			}
981 		}
982 		rbuf->which_ru = ctrl->ru_count;
983 
984 		/* skip this RU if it's already been reconstructed */
985 		if (rf_CheckRUReconstructed(raidPtr->reconControl[row]->reconMap, rbuf->failedDiskSectorOffset)) {
986 			Dprintf2("Skipping psid %ld ru %d: already reconstructed\n", ctrl->curPSID, ctrl->ru_count);
987 			continue;
988 		}
989 		break;
990 	}
991 	ctrl->headSepCounter++;
992 	if (do_new_check)
993 		CheckForNewMinHeadSep(raidPtr, row, ctrl->headSepCounter);	/* update min if needed */
994 
995 
996 	/* at this point, we have definitely decided what to do, and we have
997 	 * only to see if we can actually do it now */
998 	rbuf->parityStripeID = ctrl->curPSID;
999 	rbuf->which_ru = ctrl->ru_count;
1000 	bzero((char *) &raidPtr->recon_tracerecs[col], sizeof(raidPtr->recon_tracerecs[col]));
1001 	raidPtr->recon_tracerecs[col].reconacc = 1;
1002 	RF_ETIMER_START(raidPtr->recon_tracerecs[col].recon_timer);
1003 	retcode = TryToRead(raidPtr, row, col);
1004 	return (retcode);
1005 }
1006 
1007 /*
1008  * tries to issue the next read on the indicated disk.  We may be
1009  * blocked by (a) the heads being too far apart, or (b) recon on the
1010  * indicated RU being blocked due to a write by a user thread.  In
1011  * this case, we issue a head-sep or blockage wait request, which will
1012  * cause this same routine to be invoked again later when the blockage
1013  * has cleared.
1014  */
1015 
1016 static int
1017 TryToRead(raidPtr, row, col)
1018 	RF_Raid_t *raidPtr;
1019 	RF_RowCol_t row;
1020 	RF_RowCol_t col;
1021 {
1022 	RF_PerDiskReconCtrl_t *ctrl = &raidPtr->reconControl[row]->perDiskInfo[col];
1023 	RF_SectorCount_t sectorsPerRU = raidPtr->Layout.sectorsPerStripeUnit * raidPtr->Layout.SUsPerRU;
1024 	RF_StripeNum_t psid = ctrl->curPSID;
1025 	RF_ReconUnitNum_t which_ru = ctrl->ru_count;
1026 	RF_DiskQueueData_t *req;
1027 	int     status, created = 0;
1028 	RF_ReconParityStripeStatus_t *pssPtr;
1029 
1030 	/* if the current disk is too far ahead of the others, issue a
1031 	 * head-separation wait and return */
1032 	if (CheckHeadSeparation(raidPtr, ctrl, row, col, ctrl->headSepCounter, which_ru))
1033 		return (0);
1034 	RF_LOCK_PSS_MUTEX(raidPtr, row, psid);
1035 	pssPtr = rf_LookupRUStatus(raidPtr, raidPtr->reconControl[row]->pssTable, psid, which_ru, RF_PSS_CREATE, &created);
1036 
1037 	/* if recon is blocked on the indicated parity stripe, issue a
1038 	 * block-wait request and return. this also must mark the indicated RU
1039 	 * in the stripe as under reconstruction if not blocked. */
1040 	status = CheckForcedOrBlockedReconstruction(raidPtr, pssPtr, ctrl, row, col, psid, which_ru);
1041 	if (status == RF_PSS_RECON_BLOCKED) {
1042 		Dprintf2("RECON: Stalling psid %ld ru %d: recon blocked\n", psid, which_ru);
1043 		goto out;
1044 	} else
1045 		if (status == RF_PSS_FORCED_ON_WRITE) {
1046 			rf_CauseReconEvent(raidPtr, row, col, NULL, RF_REVENT_SKIP);
1047 			goto out;
1048 		}
1049 	/* make one last check to be sure that the indicated RU didn't get
1050 	 * reconstructed while we were waiting for something else to happen.
1051 	 * This is unfortunate in that it causes us to make this check twice
1052 	 * in the normal case.  Might want to make some attempt to re-work
1053 	 * this so that we only do this check if we've definitely blocked on
1054 	 * one of the above checks.  When this condition is detected, we may
1055 	 * have just created a bogus status entry, which we need to delete. */
1056 	if (rf_CheckRUReconstructed(raidPtr->reconControl[row]->reconMap, ctrl->rbuf->failedDiskSectorOffset)) {
1057 		Dprintf2("RECON: Skipping psid %ld ru %d: prior recon after stall\n", psid, which_ru);
1058 		if (created)
1059 			rf_PSStatusDelete(raidPtr, raidPtr->reconControl[row]->pssTable, pssPtr);
1060 		rf_CauseReconEvent(raidPtr, row, col, NULL, RF_REVENT_SKIP);
1061 		goto out;
1062 	}
1063 	/* found something to read.  issue the I/O */
1064 	Dprintf5("RECON: Read for psid %ld on row %d col %d offset %ld buf %lx\n",
1065 	    psid, row, col, ctrl->diskOffset, ctrl->rbuf->buffer);
1066 	RF_ETIMER_STOP(raidPtr->recon_tracerecs[col].recon_timer);
1067 	RF_ETIMER_EVAL(raidPtr->recon_tracerecs[col].recon_timer);
1068 	raidPtr->recon_tracerecs[col].specific.recon.recon_start_to_fetch_us =
1069 	    RF_ETIMER_VAL_US(raidPtr->recon_tracerecs[col].recon_timer);
1070 	RF_ETIMER_START(raidPtr->recon_tracerecs[col].recon_timer);
1071 
1072 	/* should be ok to use a NULL proc pointer here, all the bufs we use
1073 	 * should be in kernel space */
1074 	req = rf_CreateDiskQueueData(RF_IO_TYPE_READ, ctrl->diskOffset, sectorsPerRU, ctrl->rbuf->buffer, psid, which_ru,
1075 	    ReconReadDoneProc, (void *) ctrl, NULL, &raidPtr->recon_tracerecs[col], (void *) raidPtr, 0, NULL);
1076 
1077 	RF_ASSERT(req);		/* XXX -- fix this -- XXX */
1078 
1079 	ctrl->rbuf->arg = (void *) req;
1080 	rf_DiskIOEnqueue(&raidPtr->Queues[row][col], req, RF_IO_RECON_PRIORITY);
1081 	pssPtr->issued[col] = 1;
1082 
1083 out:
1084 	RF_UNLOCK_PSS_MUTEX(raidPtr, row, psid);
1085 	return (0);
1086 }
1087 
1088 
1089 /*
1090  * given a parity stripe ID, we want to find out whether both the
1091  * current disk and the failed disk exist in that parity stripe.  If
1092  * not, we want to skip this whole PS.  If so, we want to find the
1093  * disk offset of the start of the PS on both the current disk and the
1094  * failed disk.
1095  *
1096  * this works by getting a list of disks comprising the indicated
1097  * parity stripe, and searching the list for the current and failed
1098  * disks.  Once we've decided they both exist in the parity stripe, we
1099  * need to decide whether each is data or parity, so that we'll know
1100  * which mapping function to call to get the corresponding disk
1101  * offsets.
1102  *
1103  * this is kind of unpleasant, but doing it this way allows the
1104  * reconstruction code to use parity stripe IDs rather than physical
1105  * disks address to march through the failed disk, which greatly
1106  * simplifies a lot of code, as well as eliminating the need for a
1107  * reverse-mapping function.  I also think it will execute faster,
1108  * since the calls to the mapping module are kept to a minimum.
1109  *
1110  * ASSUMES THAT THE STRIPE IDENTIFIER IDENTIFIES THE DISKS COMPRISING
1111  * THE STRIPE IN THE CORRECT ORDER */
1112 
1113 
1114 static int
1115 ComputePSDiskOffsets(
1116     RF_Raid_t * raidPtr,	/* raid descriptor */
1117     RF_StripeNum_t psid,	/* parity stripe identifier */
1118     RF_RowCol_t row,		/* row and column of disk to find the offsets
1119 				 * for */
1120     RF_RowCol_t col,
1121     RF_SectorNum_t * outDiskOffset,
1122     RF_SectorNum_t * outFailedDiskSectorOffset,
1123     RF_RowCol_t * spRow,	/* OUT: row,col of spare unit for failed unit */
1124     RF_RowCol_t * spCol,
1125     RF_SectorNum_t * spOffset)
1126 {				/* OUT: offset into disk containing spare unit */
1127 	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
1128 	RF_RowCol_t fcol = raidPtr->reconControl[row]->fcol;
1129 	RF_RaidAddr_t sosRaidAddress;	/* start-of-stripe */
1130 	RF_RowCol_t *diskids;
1131 	u_int   i, j, k, i_offset, j_offset;
1132 	RF_RowCol_t prow, pcol;
1133 	int     testcol, testrow;
1134 	RF_RowCol_t stripe;
1135 	RF_SectorNum_t poffset;
1136 	char    i_is_parity = 0, j_is_parity = 0;
1137 	RF_RowCol_t stripeWidth = layoutPtr->numDataCol + layoutPtr->numParityCol;
1138 
1139 	/* get a listing of the disks comprising that stripe */
1140 	sosRaidAddress = rf_ParityStripeIDToRaidAddress(layoutPtr, psid);
1141 	(layoutPtr->map->IdentifyStripe) (raidPtr, sosRaidAddress, &diskids, &stripe);
1142 	RF_ASSERT(diskids);
1143 
1144 	/* reject this entire parity stripe if it does not contain the
1145 	 * indicated disk or it does not contain the failed disk */
1146 	if (row != stripe)
1147 		goto skipit;
1148 	for (i = 0; i < stripeWidth; i++) {
1149 		if (col == diskids[i])
1150 			break;
1151 	}
1152 	if (i == stripeWidth)
1153 		goto skipit;
1154 	for (j = 0; j < stripeWidth; j++) {
1155 		if (fcol == diskids[j])
1156 			break;
1157 	}
1158 	if (j == stripeWidth) {
1159 		goto skipit;
1160 	}
1161 	/* find out which disk the parity is on */
1162 	(layoutPtr->map->MapParity) (raidPtr, sosRaidAddress, &prow, &pcol, &poffset, RF_DONT_REMAP);
1163 
1164 	/* find out if either the current RU or the failed RU is parity */
1165 	/* also, if the parity occurs in this stripe prior to the data and/or
1166 	 * failed col, we need to decrement i and/or j */
1167 	for (k = 0; k < stripeWidth; k++)
1168 		if (diskids[k] == pcol)
1169 			break;
1170 	RF_ASSERT(k < stripeWidth);
1171 	i_offset = i;
1172 	j_offset = j;
1173 	if (k < i)
1174 		i_offset--;
1175 	else
1176 		if (k == i) {
1177 			i_is_parity = 1;
1178 			i_offset = 0;
1179 		}		/* set offsets to zero to disable multiply
1180 				 * below */
1181 	if (k < j)
1182 		j_offset--;
1183 	else
1184 		if (k == j) {
1185 			j_is_parity = 1;
1186 			j_offset = 0;
1187 		}
1188 	/* at this point, [ij]_is_parity tells us whether the [current,failed]
1189 	 * disk is parity at the start of this RU, and, if data, "[ij]_offset"
1190 	 * tells us how far into the stripe the [current,failed] disk is. */
1191 
1192 	/* call the mapping routine to get the offset into the current disk,
1193 	 * repeat for failed disk. */
1194 	if (i_is_parity)
1195 		layoutPtr->map->MapParity(raidPtr, sosRaidAddress + i_offset * layoutPtr->sectorsPerStripeUnit, &testrow, &testcol, outDiskOffset, RF_DONT_REMAP);
1196 	else
1197 		layoutPtr->map->MapSector(raidPtr, sosRaidAddress + i_offset * layoutPtr->sectorsPerStripeUnit, &testrow, &testcol, outDiskOffset, RF_DONT_REMAP);
1198 
1199 	RF_ASSERT(row == testrow && col == testcol);
1200 
1201 	if (j_is_parity)
1202 		layoutPtr->map->MapParity(raidPtr, sosRaidAddress + j_offset * layoutPtr->sectorsPerStripeUnit, &testrow, &testcol, outFailedDiskSectorOffset, RF_DONT_REMAP);
1203 	else
1204 		layoutPtr->map->MapSector(raidPtr, sosRaidAddress + j_offset * layoutPtr->sectorsPerStripeUnit, &testrow, &testcol, outFailedDiskSectorOffset, RF_DONT_REMAP);
1205 	RF_ASSERT(row == testrow && fcol == testcol);
1206 
1207 	/* now locate the spare unit for the failed unit */
1208 	if (layoutPtr->map->flags & RF_DISTRIBUTE_SPARE) {
1209 		if (j_is_parity)
1210 			layoutPtr->map->MapParity(raidPtr, sosRaidAddress + j_offset * layoutPtr->sectorsPerStripeUnit, spRow, spCol, spOffset, RF_REMAP);
1211 		else
1212 			layoutPtr->map->MapSector(raidPtr, sosRaidAddress + j_offset * layoutPtr->sectorsPerStripeUnit, spRow, spCol, spOffset, RF_REMAP);
1213 	} else {
1214 		*spRow = raidPtr->reconControl[row]->spareRow;
1215 		*spCol = raidPtr->reconControl[row]->spareCol;
1216 		*spOffset = *outFailedDiskSectorOffset;
1217 	}
1218 
1219 	return (0);
1220 
1221 skipit:
1222 	Dprintf3("RECON: Skipping psid %ld: nothing needed from r%d c%d\n",
1223 	    psid, row, col);
1224 	return (1);
1225 }
1226 /* this is called when a buffer has become ready to write to the replacement disk */
1227 static int
1228 IssueNextWriteRequest(raidPtr, row)
1229 	RF_Raid_t *raidPtr;
1230 	RF_RowCol_t row;
1231 {
1232 	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
1233 	RF_SectorCount_t sectorsPerRU = layoutPtr->sectorsPerStripeUnit * layoutPtr->SUsPerRU;
1234 	RF_RowCol_t fcol = raidPtr->reconControl[row]->fcol;
1235 	RF_ReconBuffer_t *rbuf;
1236 	RF_DiskQueueData_t *req;
1237 
1238 	rbuf = rf_GetFullReconBuffer(raidPtr->reconControl[row]);
1239 	RF_ASSERT(rbuf);	/* there must be one available, or we wouldn't
1240 				 * have gotten the event that sent us here */
1241 	RF_ASSERT(rbuf->pssPtr);
1242 
1243 	rbuf->pssPtr->writeRbuf = rbuf;
1244 	rbuf->pssPtr = NULL;
1245 
1246 	Dprintf7("RECON: New write (r %d c %d offs %d) for psid %ld ru %d (failed disk offset %ld) buf %lx\n",
1247 	    rbuf->spRow, rbuf->spCol, rbuf->spOffset, rbuf->parityStripeID,
1248 	    rbuf->which_ru, rbuf->failedDiskSectorOffset, rbuf->buffer);
1249 	Dprintf6("RECON: new write psid %ld   %02x %02x %02x %02x %02x\n",
1250 	    rbuf->parityStripeID, rbuf->buffer[0] & 0xff, rbuf->buffer[1] & 0xff,
1251 	    rbuf->buffer[2] & 0xff, rbuf->buffer[3] & 0xff, rbuf->buffer[4] & 0xff);
1252 
1253 	/* should be ok to use a NULL b_proc here b/c all addrs should be in
1254 	 * kernel space */
1255 	req = rf_CreateDiskQueueData(RF_IO_TYPE_WRITE, rbuf->spOffset,
1256 	    sectorsPerRU, rbuf->buffer,
1257 	    rbuf->parityStripeID, rbuf->which_ru,
1258 	    ReconWriteDoneProc, (void *) rbuf, NULL,
1259 	    &raidPtr->recon_tracerecs[fcol],
1260 	    (void *) raidPtr, 0, NULL);
1261 
1262 	RF_ASSERT(req);		/* XXX -- fix this -- XXX */
1263 
1264 	rbuf->arg = (void *) req;
1265 	rf_DiskIOEnqueue(&raidPtr->Queues[rbuf->spRow][rbuf->spCol], req, RF_IO_RECON_PRIORITY);
1266 
1267 	return (0);
1268 }
1269 
1270 /*
1271  * this gets called upon the completion of a reconstruction read
1272  * operation the arg is a pointer to the per-disk reconstruction
1273  * control structure for the process that just finished a read.
1274  *
1275  * called at interrupt context in the kernel, so don't do anything
1276  * illegal here.
1277  */
1278 static int
1279 ReconReadDoneProc(arg, status)
1280 	void   *arg;
1281 	int     status;
1282 {
1283 	RF_PerDiskReconCtrl_t *ctrl = (RF_PerDiskReconCtrl_t *) arg;
1284 	RF_Raid_t *raidPtr = ctrl->reconCtrl->reconDesc->raidPtr;
1285 
1286 	if (status) {
1287 		/*
1288 	         * XXX
1289 	         */
1290 		printf("Recon read failed!\n");
1291 		RF_PANIC();
1292 	}
1293 	RF_ETIMER_STOP(raidPtr->recon_tracerecs[ctrl->col].recon_timer);
1294 	RF_ETIMER_EVAL(raidPtr->recon_tracerecs[ctrl->col].recon_timer);
1295 	raidPtr->recon_tracerecs[ctrl->col].specific.recon.recon_fetch_to_return_us =
1296 	    RF_ETIMER_VAL_US(raidPtr->recon_tracerecs[ctrl->col].recon_timer);
1297 	RF_ETIMER_START(raidPtr->recon_tracerecs[ctrl->col].recon_timer);
1298 
1299 	rf_CauseReconEvent(raidPtr, ctrl->row, ctrl->col, NULL, RF_REVENT_READDONE);
1300 	return (0);
1301 }
1302 /* this gets called upon the completion of a reconstruction write operation.
1303  * the arg is a pointer to the rbuf that was just written
1304  *
1305  * called at interrupt context in the kernel, so don't do anything illegal here.
1306  */
1307 static int
1308 ReconWriteDoneProc(arg, status)
1309 	void   *arg;
1310 	int     status;
1311 {
1312 	RF_ReconBuffer_t *rbuf = (RF_ReconBuffer_t *) arg;
1313 
1314 	Dprintf2("Reconstruction completed on psid %ld ru %d\n", rbuf->parityStripeID, rbuf->which_ru);
1315 	if (status) {
1316 		printf("Recon write failed!\n");	/* fprintf(stderr,"Recon
1317 							 * write failed!\n"); */
1318 		RF_PANIC();
1319 	}
1320 	rf_CauseReconEvent((RF_Raid_t *) rbuf->raidPtr, rbuf->row, rbuf->col, arg, RF_REVENT_WRITEDONE);
1321 	return (0);
1322 }
1323 
1324 
1325 /*
1326  * computes a new minimum head sep, and wakes up anyone who needs to
1327  * be woken as a result
1328  */
1329 static void
1330 CheckForNewMinHeadSep(raidPtr, row, hsCtr)
1331 	RF_Raid_t *raidPtr;
1332 	RF_RowCol_t row;
1333 	RF_HeadSepLimit_t hsCtr;
1334 {
1335 	RF_ReconCtrl_t *reconCtrlPtr = raidPtr->reconControl[row];
1336 	RF_HeadSepLimit_t new_min;
1337 	RF_RowCol_t i;
1338 	RF_CallbackDesc_t *p;
1339 	RF_ASSERT(hsCtr >= reconCtrlPtr->minHeadSepCounter);	/* from the definition
1340 								 * of a minimum */
1341 
1342 
1343 	RF_LOCK_MUTEX(reconCtrlPtr->rb_mutex);
1344 
1345 	new_min = ~(1L << (8 * sizeof(long) - 1));	/* 0x7FFF....FFF */
1346 	for (i = 0; i < raidPtr->numCol; i++)
1347 		if (i != reconCtrlPtr->fcol) {
1348 			if (reconCtrlPtr->perDiskInfo[i].headSepCounter < new_min)
1349 				new_min = reconCtrlPtr->perDiskInfo[i].headSepCounter;
1350 		}
1351 	/* set the new minimum and wake up anyone who can now run again */
1352 	if (new_min != reconCtrlPtr->minHeadSepCounter) {
1353 		reconCtrlPtr->minHeadSepCounter = new_min;
1354 		Dprintf1("RECON:  new min head pos counter val is %ld\n", new_min);
1355 		while (reconCtrlPtr->headSepCBList) {
1356 			if (reconCtrlPtr->headSepCBList->callbackArg.v > new_min)
1357 				break;
1358 			p = reconCtrlPtr->headSepCBList;
1359 			reconCtrlPtr->headSepCBList = p->next;
1360 			p->next = NULL;
1361 			rf_CauseReconEvent(raidPtr, p->row, p->col, NULL, RF_REVENT_HEADSEPCLEAR);
1362 			rf_FreeCallbackDesc(p);
1363 		}
1364 
1365 	}
1366 	RF_UNLOCK_MUTEX(reconCtrlPtr->rb_mutex);
1367 }
1368 
1369 /*
1370  * checks to see that the maximum head separation will not be violated
1371  * if we initiate a reconstruction I/O on the indicated disk.
1372  * Limiting the maximum head separation between two disks eliminates
1373  * the nasty buffer-stall conditions that occur when one disk races
1374  * ahead of the others and consumes all of the floating recon buffers.
1375  * This code is complex and unpleasant but it's necessary to avoid
1376  * some very nasty, albeit fairly rare, reconstruction behavior.
1377  *
1378  * returns non-zero if and only if we have to stop working on the
1379  * indicated disk due to a head-separation delay.
1380  */
1381 static int
1382 CheckHeadSeparation(
1383     RF_Raid_t * raidPtr,
1384     RF_PerDiskReconCtrl_t * ctrl,
1385     RF_RowCol_t row,
1386     RF_RowCol_t col,
1387     RF_HeadSepLimit_t hsCtr,
1388     RF_ReconUnitNum_t which_ru)
1389 {
1390 	RF_ReconCtrl_t *reconCtrlPtr = raidPtr->reconControl[row];
1391 	RF_CallbackDesc_t *cb, *p, *pt;
1392 	int     retval = 0;
1393 
1394 	/* if we're too far ahead of the slowest disk, stop working on this
1395 	 * disk until the slower ones catch up.  We do this by scheduling a
1396 	 * wakeup callback for the time when the slowest disk has caught up.
1397 	 * We define "caught up" with 20% hysteresis, i.e. the head separation
1398 	 * must have fallen to at most 80% of the max allowable head
1399 	 * separation before we'll wake up.
1400 	 *
1401 	 */
1402 	RF_LOCK_MUTEX(reconCtrlPtr->rb_mutex);
1403 	if ((raidPtr->headSepLimit >= 0) &&
1404 	    ((ctrl->headSepCounter - reconCtrlPtr->minHeadSepCounter) > raidPtr->headSepLimit)) {
1405 		Dprintf6("raid%d: RECON: head sep stall: row %d col %d hsCtr %ld minHSCtr %ld limit %ld\n",
1406 			 raidPtr->raidid, row, col, ctrl->headSepCounter,
1407 			 reconCtrlPtr->minHeadSepCounter,
1408 			 raidPtr->headSepLimit);
1409 		cb = rf_AllocCallbackDesc();
1410 		/* the minHeadSepCounter value we have to get to before we'll
1411 		 * wake up.  build in 20% hysteresis. */
1412 		cb->callbackArg.v = (ctrl->headSepCounter - raidPtr->headSepLimit + raidPtr->headSepLimit / 5);
1413 		cb->row = row;
1414 		cb->col = col;
1415 		cb->next = NULL;
1416 
1417 		/* insert this callback descriptor into the sorted list of
1418 		 * pending head-sep callbacks */
1419 		p = reconCtrlPtr->headSepCBList;
1420 		if (!p)
1421 			reconCtrlPtr->headSepCBList = cb;
1422 		else
1423 			if (cb->callbackArg.v < p->callbackArg.v) {
1424 				cb->next = reconCtrlPtr->headSepCBList;
1425 				reconCtrlPtr->headSepCBList = cb;
1426 			} else {
1427 				for (pt = p, p = p->next; p && (p->callbackArg.v < cb->callbackArg.v); pt = p, p = p->next);
1428 				cb->next = p;
1429 				pt->next = cb;
1430 			}
1431 		retval = 1;
1432 #if RF_RECON_STATS > 0
1433 		ctrl->reconCtrl->reconDesc->hsStallCount++;
1434 #endif				/* RF_RECON_STATS > 0 */
1435 	}
1436 	RF_UNLOCK_MUTEX(reconCtrlPtr->rb_mutex);
1437 
1438 	return (retval);
1439 }
1440 /*
1441  * checks to see if reconstruction has been either forced or blocked
1442  * by a user operation.  if forced, we skip this RU entirely.  else if
1443  * blocked, put ourselves on the wait list.  else return 0.
1444  *
1445  * ASSUMES THE PSS MUTEX IS LOCKED UPON ENTRY
1446  */
1447 static int
1448 CheckForcedOrBlockedReconstruction(
1449     RF_Raid_t * raidPtr,
1450     RF_ReconParityStripeStatus_t * pssPtr,
1451     RF_PerDiskReconCtrl_t * ctrl,
1452     RF_RowCol_t row,
1453     RF_RowCol_t col,
1454     RF_StripeNum_t psid,
1455     RF_ReconUnitNum_t which_ru)
1456 {
1457 	RF_CallbackDesc_t *cb;
1458 	int     retcode = 0;
1459 
1460 	if ((pssPtr->flags & RF_PSS_FORCED_ON_READ) || (pssPtr->flags & RF_PSS_FORCED_ON_WRITE))
1461 		retcode = RF_PSS_FORCED_ON_WRITE;
1462 	else
1463 		if (pssPtr->flags & RF_PSS_RECON_BLOCKED) {
1464 			Dprintf4("RECON: row %d col %d blocked at psid %ld ru %d\n", row, col, psid, which_ru);
1465 			cb = rf_AllocCallbackDesc();	/* append ourselves to
1466 							 * the blockage-wait
1467 							 * list */
1468 			cb->row = row;
1469 			cb->col = col;
1470 			cb->next = pssPtr->blockWaitList;
1471 			pssPtr->blockWaitList = cb;
1472 			retcode = RF_PSS_RECON_BLOCKED;
1473 		}
1474 	if (!retcode)
1475 		pssPtr->flags |= RF_PSS_UNDER_RECON;	/* mark this RU as under
1476 							 * reconstruction */
1477 
1478 	return (retcode);
1479 }
1480 /*
1481  * if reconstruction is currently ongoing for the indicated stripeID,
1482  * reconstruction is forced to completion and we return non-zero to
1483  * indicate that the caller must wait.  If not, then reconstruction is
1484  * blocked on the indicated stripe and the routine returns zero.  If
1485  * and only if we return non-zero, we'll cause the cbFunc to get
1486  * invoked with the cbArg when the reconstruction has completed.
1487  */
1488 int
1489 rf_ForceOrBlockRecon(raidPtr, asmap, cbFunc, cbArg)
1490 	RF_Raid_t *raidPtr;
1491 	RF_AccessStripeMap_t *asmap;
1492 	void    (*cbFunc) (RF_Raid_t *, void *);
1493 	void   *cbArg;
1494 {
1495 	RF_RowCol_t row = asmap->physInfo->row;	/* which row of the array
1496 						 * we're working on */
1497 	RF_StripeNum_t stripeID = asmap->stripeID;	/* the stripe ID we're
1498 							 * forcing recon on */
1499 	RF_SectorCount_t sectorsPerRU = raidPtr->Layout.sectorsPerStripeUnit * raidPtr->Layout.SUsPerRU;	/* num sects in one RU */
1500 	RF_ReconParityStripeStatus_t *pssPtr;	/* a pointer to the parity
1501 						 * stripe status structure */
1502 	RF_StripeNum_t psid;	/* parity stripe id */
1503 	RF_SectorNum_t offset, fd_offset;	/* disk offset, failed-disk
1504 						 * offset */
1505 	RF_RowCol_t *diskids;
1506 	RF_RowCol_t stripe;
1507 	RF_ReconUnitNum_t which_ru;	/* RU within parity stripe */
1508 	RF_RowCol_t fcol, diskno, i;
1509 	RF_ReconBuffer_t *new_rbuf;	/* ptr to newly allocated rbufs */
1510 	RF_DiskQueueData_t *req;/* disk I/O req to be enqueued */
1511 	RF_CallbackDesc_t *cb;
1512 	int     created = 0, nPromoted;
1513 
1514 	psid = rf_MapStripeIDToParityStripeID(&raidPtr->Layout, stripeID, &which_ru);
1515 
1516 	RF_LOCK_PSS_MUTEX(raidPtr, row, psid);
1517 
1518 	pssPtr = rf_LookupRUStatus(raidPtr, raidPtr->reconControl[row]->pssTable, psid, which_ru, RF_PSS_CREATE | RF_PSS_RECON_BLOCKED, &created);
1519 
1520 	/* if recon is not ongoing on this PS, just return */
1521 	if (!(pssPtr->flags & RF_PSS_UNDER_RECON)) {
1522 		RF_UNLOCK_PSS_MUTEX(raidPtr, row, psid);
1523 		return (0);
1524 	}
1525 	/* otherwise, we have to wait for reconstruction to complete on this
1526 	 * RU. */
1527 	/* In order to avoid waiting for a potentially large number of
1528 	 * low-priority accesses to complete, we force a normal-priority (i.e.
1529 	 * not low-priority) reconstruction on this RU. */
1530 	if (!(pssPtr->flags & RF_PSS_FORCED_ON_WRITE) && !(pssPtr->flags & RF_PSS_FORCED_ON_READ)) {
1531 		DDprintf1("Forcing recon on psid %ld\n", psid);
1532 		pssPtr->flags |= RF_PSS_FORCED_ON_WRITE;	/* mark this RU as under
1533 								 * forced recon */
1534 		pssPtr->flags &= ~RF_PSS_RECON_BLOCKED;	/* clear the blockage
1535 							 * that we just set */
1536 		fcol = raidPtr->reconControl[row]->fcol;
1537 
1538 		/* get a listing of the disks comprising the indicated stripe */
1539 		(raidPtr->Layout.map->IdentifyStripe) (raidPtr, asmap->raidAddress, &diskids, &stripe);
1540 		RF_ASSERT(row == stripe);
1541 
1542 		/* For previously issued reads, elevate them to normal
1543 		 * priority.  If the I/O has already completed, it won't be
1544 		 * found in the queue, and hence this will be a no-op. For
1545 		 * unissued reads, allocate buffers and issue new reads.  The
1546 		 * fact that we've set the FORCED bit means that the regular
1547 		 * recon procs will not re-issue these reqs */
1548 		for (i = 0; i < raidPtr->Layout.numDataCol + raidPtr->Layout.numParityCol; i++)
1549 			if ((diskno = diskids[i]) != fcol) {
1550 				if (pssPtr->issued[diskno]) {
1551 					nPromoted = rf_DiskIOPromote(&raidPtr->Queues[row][diskno], psid, which_ru);
1552 					if (rf_reconDebug && nPromoted)
1553 						printf("raid%d: promoted read from row %d col %d\n", raidPtr->raidid, row, diskno);
1554 				} else {
1555 					new_rbuf = rf_MakeReconBuffer(raidPtr, row, diskno, RF_RBUF_TYPE_FORCED);	/* create new buf */
1556 					ComputePSDiskOffsets(raidPtr, psid, row, diskno, &offset, &fd_offset,
1557 					    &new_rbuf->spRow, &new_rbuf->spCol, &new_rbuf->spOffset);	/* find offsets & spare
1558 													 * location */
1559 					new_rbuf->parityStripeID = psid;	/* fill in the buffer */
1560 					new_rbuf->which_ru = which_ru;
1561 					new_rbuf->failedDiskSectorOffset = fd_offset;
1562 					new_rbuf->priority = RF_IO_NORMAL_PRIORITY;
1563 
1564 					/* use NULL b_proc b/c all addrs
1565 					 * should be in kernel space */
1566 					req = rf_CreateDiskQueueData(RF_IO_TYPE_READ, offset + which_ru * sectorsPerRU, sectorsPerRU, new_rbuf->buffer,
1567 					    psid, which_ru, (int (*) (void *, int)) ForceReconReadDoneProc, (void *) new_rbuf, NULL,
1568 					    NULL, (void *) raidPtr, 0, NULL);
1569 
1570 					RF_ASSERT(req);	/* XXX -- fix this --
1571 							 * XXX */
1572 
1573 					new_rbuf->arg = req;
1574 					rf_DiskIOEnqueue(&raidPtr->Queues[row][diskno], req, RF_IO_NORMAL_PRIORITY);	/* enqueue the I/O */
1575 					Dprintf3("raid%d: Issued new read req on row %d col %d\n", raidPtr->raidid, row, diskno);
1576 				}
1577 			}
1578 		/* if the write is sitting in the disk queue, elevate its
1579 		 * priority */
1580 		if (rf_DiskIOPromote(&raidPtr->Queues[row][fcol], psid, which_ru))
1581 			printf("raid%d: promoted write to row %d col %d\n",
1582 			       raidPtr->raidid, row, fcol);
1583 	}
1584 	/* install a callback descriptor to be invoked when recon completes on
1585 	 * this parity stripe. */
1586 	cb = rf_AllocCallbackDesc();
1587 	/* XXX the following is bogus.. These functions don't really match!!
1588 	 * GO */
1589 	cb->callbackFunc = (void (*) (RF_CBParam_t)) cbFunc;
1590 	cb->callbackArg.p = (void *) cbArg;
1591 	cb->next = pssPtr->procWaitList;
1592 	pssPtr->procWaitList = cb;
1593 	DDprintf2("raid%d: Waiting for forced recon on psid %ld\n",
1594 		  raidPtr->raidid, psid);
1595 
1596 	RF_UNLOCK_PSS_MUTEX(raidPtr, row, psid);
1597 	return (1);
1598 }
1599 /* called upon the completion of a forced reconstruction read.
1600  * all we do is schedule the FORCEDREADONE event.
1601  * called at interrupt context in the kernel, so don't do anything illegal here.
1602  */
1603 static void
1604 ForceReconReadDoneProc(arg, status)
1605 	void   *arg;
1606 	int     status;
1607 {
1608 	RF_ReconBuffer_t *rbuf = arg;
1609 
1610 	if (status) {
1611 		printf("Forced recon read failed!\n");	/* fprintf(stderr,"Forced
1612 							 *  recon read
1613 							 * failed!\n"); */
1614 		RF_PANIC();
1615 	}
1616 	rf_CauseReconEvent((RF_Raid_t *) rbuf->raidPtr, rbuf->row, rbuf->col, (void *) rbuf, RF_REVENT_FORCEDREADDONE);
1617 }
1618 /* releases a block on the reconstruction of the indicated stripe */
1619 int
1620 rf_UnblockRecon(raidPtr, asmap)
1621 	RF_Raid_t *raidPtr;
1622 	RF_AccessStripeMap_t *asmap;
1623 {
1624 	RF_RowCol_t row = asmap->origRow;
1625 	RF_StripeNum_t stripeID = asmap->stripeID;
1626 	RF_ReconParityStripeStatus_t *pssPtr;
1627 	RF_ReconUnitNum_t which_ru;
1628 	RF_StripeNum_t psid;
1629 	int     created = 0;
1630 	RF_CallbackDesc_t *cb;
1631 
1632 	psid = rf_MapStripeIDToParityStripeID(&raidPtr->Layout, stripeID, &which_ru);
1633 	RF_LOCK_PSS_MUTEX(raidPtr, row, psid);
1634 	pssPtr = rf_LookupRUStatus(raidPtr, raidPtr->reconControl[row]->pssTable, psid, which_ru, RF_PSS_NONE, &created);
1635 
1636 	/* When recon is forced, the pss desc can get deleted before we get
1637 	 * back to unblock recon. But, this can _only_ happen when recon is
1638 	 * forced. It would be good to put some kind of sanity check here, but
1639 	 * how to decide if recon was just forced or not? */
1640 	if (!pssPtr) {
1641 		/* printf("Warning: no pss descriptor upon unblock on psid %ld
1642 		 * RU %d\n",psid,which_ru); */
1643 		if (rf_reconDebug || rf_pssDebug)
1644 			printf("Warning: no pss descriptor upon unblock on psid %ld RU %d\n", (long) psid, which_ru);
1645 		goto out;
1646 	}
1647 	pssPtr->blockCount--;
1648 	Dprintf3("raid%d: unblocking recon on psid %ld: blockcount is %d\n",
1649 		 raidPtr->raidid, psid, pssPtr->blockCount);
1650 	if (pssPtr->blockCount == 0) {	/* if recon blockage has been released */
1651 
1652 		/* unblock recon before calling CauseReconEvent in case
1653 		 * CauseReconEvent causes us to try to issue a new read before
1654 		 * returning here. */
1655 		pssPtr->flags &= ~RF_PSS_RECON_BLOCKED;
1656 
1657 
1658 		while (pssPtr->blockWaitList) {
1659 			/* spin through the block-wait list and
1660 			   release all the waiters */
1661 			cb = pssPtr->blockWaitList;
1662 			pssPtr->blockWaitList = cb->next;
1663 			cb->next = NULL;
1664 			rf_CauseReconEvent(raidPtr, cb->row, cb->col, NULL, RF_REVENT_BLOCKCLEAR);
1665 			rf_FreeCallbackDesc(cb);
1666 		}
1667 		if (!(pssPtr->flags & RF_PSS_UNDER_RECON)) {
1668 			/* if no recon was requested while recon was blocked */
1669 			rf_PSStatusDelete(raidPtr, raidPtr->reconControl[row]->pssTable, pssPtr);
1670 		}
1671 	}
1672 out:
1673 	RF_UNLOCK_PSS_MUTEX(raidPtr, row, psid);
1674 	return (0);
1675 }
1676