xref: /netbsd-src/sys/dev/raidframe/rf_reconstruct.c (revision e4d7c2e329d54c97e0c0bd3016bbe74f550c3d5e)
1 /*	$NetBSD: rf_reconstruct.c,v 1.20 2000/02/25 17:14:18 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 
404 	lp = raidPtr->Layout.map;
405 	if (lp->SubmitReconBuffer) {
406 		/*
407 	         * The current infrastructure only supports reconstructing one
408 	         * disk at a time for each array.
409 	         */
410 		RF_LOCK_MUTEX(raidPtr->mutex);
411 		if ((raidPtr->Disks[row][col].status == rf_ds_optimal) &&
412 		    (raidPtr->numFailures > 0)) {
413 			/* XXX 0 above shouldn't be constant!!! */
414 			/* some component other than this has failed.
415 			   Let's not make things worse than they already
416 			   are... */
417 			printf("RAIDFRAME: Unable to reconstruct to disk at:\n");
418 			printf("      Row: %d Col: %d   Too many failures.\n",
419 			       row, col);
420 			RF_UNLOCK_MUTEX(raidPtr->mutex);
421 			return (EINVAL);
422 		}
423 		if (raidPtr->Disks[row][col].status == rf_ds_reconstructing) {
424 			printf("RAIDFRAME: Unable to reconstruct to disk at:\n");
425 			printf("      Row: %d Col: %d   Reconstruction already occuring!\n", row, col);
426 
427 			RF_UNLOCK_MUTEX(raidPtr->mutex);
428 			return (EINVAL);
429 		}
430 
431 
432 		if (raidPtr->Disks[row][col].status != rf_ds_failed) {
433 			/* "It's gone..." */
434 			raidPtr->numFailures++;
435 			raidPtr->Disks[row][col].status = rf_ds_failed;
436 			raidPtr->status[row] = rf_rs_degraded;
437 			rf_update_component_labels(raidPtr);
438 		}
439 
440 		while (raidPtr->reconInProgress) {
441 			RF_WAIT_COND(raidPtr->waitForReconCond, raidPtr->mutex);
442 		}
443 
444 		raidPtr->reconInProgress++;
445 
446 
447 		/* first look for a spare drive onto which to reconstruct
448 		   the data.  spare disk descriptors are stored in row 0.
449 		   This may have to change eventually */
450 
451 		/* Actually, we don't care if it's failed or not...
452 		   On a RAID set with correct parity, this function
453 		   should be callable on any component without ill affects. */
454 		/* RF_ASSERT(raidPtr->Disks[row][col].status == rf_ds_failed);
455 		 */
456 
457 		if (raidPtr->Layout.map->flags & RF_DISTRIBUTE_SPARE) {
458 			RF_ERRORMSG2("Unable to reconstruct to disk at row %d col %d: operation not supported for RF_DISTRIBUTE_SPARE\n", row, col);
459 
460 			raidPtr->reconInProgress--;
461 			RF_UNLOCK_MUTEX(raidPtr->mutex);
462 			return (EINVAL);
463 		}
464 
465 		/* XXX need goop here to see if the disk is alive,
466 		   and, if not, make it so...  */
467 
468 
469 
470 		badDisk = &raidPtr->Disks[row][col];
471 
472 		proc = raidPtr->engine_thread;
473 
474 		/* This device may have been opened successfully the
475 		   first time. Close it before trying to open it again.. */
476 
477 		if (raidPtr->raid_cinfo[row][col].ci_vp != NULL) {
478 			printf("Closed the open device: %s\n",
479 			       raidPtr->Disks[row][col].devname);
480 			if (raidPtr->Disks[row][col].auto_configured == 1) {
481 				VOP_CLOSE(raidPtr->raid_cinfo[row][col].ci_vp,
482 					  FREAD, NOCRED, 0);
483 				vput(raidPtr->raid_cinfo[row][col].ci_vp);
484 
485 			} else {
486 				VOP_UNLOCK(raidPtr->raid_cinfo[row][col].ci_vp, 0);
487 				(void) vn_close(raidPtr->raid_cinfo[row][col].ci_vp,
488 					FREAD | FWRITE, proc->p_ucred, proc);
489 			}
490 			raidPtr->raid_cinfo[row][col].ci_vp = NULL;
491 		}
492 		/* note that this disk was *not* auto_configured (any longer)*/
493 		raidPtr->Disks[row][col].auto_configured = 0;
494 
495 		printf("About to (re-)open the device for rebuilding: %s\n",
496 		       raidPtr->Disks[row][col].devname);
497 
498 		retcode = raidlookup(raidPtr->Disks[row][col].devname,
499 				     proc, &vp);
500 
501 		if (retcode) {
502 			printf("raid%d: rebuilding: raidlookup on device: %s failed: %d!\n",raidPtr->raidid,
503 			       raidPtr->Disks[row][col].devname, retcode);
504 
505 			/* XXX the component isn't responding properly...
506 			   must be still dead :-( */
507 			raidPtr->reconInProgress--;
508 			RF_UNLOCK_MUTEX(raidPtr->mutex);
509 			return(retcode);
510 
511 		} else {
512 
513 			/* Ok, so we can at least do a lookup...
514 			   How about actually getting a vp for it? */
515 
516 			if ((retcode = VOP_GETATTR(vp, &va, proc->p_ucred,
517 						   proc)) != 0) {
518 				raidPtr->reconInProgress--;
519 				RF_UNLOCK_MUTEX(raidPtr->mutex);
520 				return(retcode);
521 			}
522 			retcode = VOP_IOCTL(vp, DIOCGPART, (caddr_t) & dpart,
523 					    FREAD, proc->p_ucred, proc);
524 			if (retcode) {
525 				raidPtr->reconInProgress--;
526 				RF_UNLOCK_MUTEX(raidPtr->mutex);
527 				return(retcode);
528 			}
529 			raidPtr->Disks[row][col].blockSize =
530 				dpart.disklab->d_secsize;
531 
532 			raidPtr->Disks[row][col].numBlocks =
533 				dpart.part->p_size - rf_protectedSectors;
534 
535 			raidPtr->raid_cinfo[row][col].ci_vp = vp;
536 			raidPtr->raid_cinfo[row][col].ci_dev = va.va_rdev;
537 
538 			raidPtr->Disks[row][col].dev = va.va_rdev;
539 
540 			/* we allow the user to specify that only a
541 			   fraction of the disks should be used this is
542 			   just for debug:  it speeds up
543 			 * the parity scan */
544 			raidPtr->Disks[row][col].numBlocks =
545 				raidPtr->Disks[row][col].numBlocks *
546 				rf_sizePercentage / 100;
547 		}
548 
549 
550 
551 		spareDiskPtr = &raidPtr->Disks[row][col];
552 		spareDiskPtr->status = rf_ds_used_spare;
553 
554 		printf("RECON: initiating in-place reconstruction on\n");
555 		printf("       row %d col %d -> spare at row %d col %d\n",
556 		       row, col, row, col);
557 
558 		RF_UNLOCK_MUTEX(raidPtr->mutex);
559 
560 		reconDesc = AllocRaidReconDesc((void *) raidPtr, row, col,
561 					       spareDiskPtr, numDisksDone,
562 					       row, col);
563 		raidPtr->reconDesc = (void *) reconDesc;
564 #if RF_RECON_STATS > 0
565 		reconDesc->hsStallCount = 0;
566 		reconDesc->numReconExecDelays = 0;
567 		reconDesc->numReconEventWaits = 0;
568 #endif				/* RF_RECON_STATS > 0 */
569 		reconDesc->reconExecTimerRunning = 0;
570 		reconDesc->reconExecTicks = 0;
571 		reconDesc->maxReconExecTicks = 0;
572 		rc = rf_ContinueReconstructFailedDisk(reconDesc);
573 
574 		RF_LOCK_MUTEX(raidPtr->mutex);
575 		raidPtr->reconInProgress--;
576 		RF_UNLOCK_MUTEX(raidPtr->mutex);
577 
578 	} else {
579 		RF_ERRORMSG1("RECON: no way to reconstruct failed disk for arch %c\n",
580 			     lp->parityConfig);
581 		rc = EIO;
582 	}
583 	RF_LOCK_MUTEX(raidPtr->mutex);
584 
585 	if (!rc) {
586 		/* Need to set these here, as at this point it'll be claiming
587 		   that the disk is in rf_ds_spared!  But we know better :-) */
588 
589 		raidPtr->Disks[row][col].status = rf_ds_optimal;
590 		raidPtr->status[row] = rf_rs_optimal;
591 
592 		/* fix up the component label */
593 		/* Don't actually need the read here.. */
594 		raidread_component_label(raidPtr->raid_cinfo[row][col].ci_dev,
595 					 raidPtr->raid_cinfo[row][col].ci_vp,
596 					 &c_label);
597 
598 		raid_init_component_label(raidPtr, &c_label);
599 
600 		c_label.row = row;
601 		c_label.column = col;
602 
603 		raidwrite_component_label(raidPtr->raid_cinfo[row][col].ci_dev,
604 					  raidPtr->raid_cinfo[row][col].ci_vp,
605 					  &c_label);
606 
607 	}
608 	RF_UNLOCK_MUTEX(raidPtr->mutex);
609 	RF_SIGNAL_COND(raidPtr->waitForReconCond);
610 	wakeup(&raidPtr->waitForReconCond);
611 	return (rc);
612 }
613 
614 
615 int
616 rf_ContinueReconstructFailedDisk(reconDesc)
617 	RF_RaidReconDesc_t *reconDesc;
618 {
619 	RF_Raid_t *raidPtr = reconDesc->raidPtr;
620 	RF_RowCol_t row = reconDesc->row;
621 	RF_RowCol_t col = reconDesc->col;
622 	RF_RowCol_t srow = reconDesc->srow;
623 	RF_RowCol_t scol = reconDesc->scol;
624 	RF_ReconMap_t *mapPtr;
625 
626 	RF_ReconEvent_t *event;
627 	struct timeval etime, elpsd;
628 	unsigned long xor_s, xor_resid_us;
629 	int     retcode, i, ds;
630 
631 	switch (reconDesc->state) {
632 
633 
634 	case 0:
635 
636 		raidPtr->accumXorTimeUs = 0;
637 
638 		/* create one trace record per physical disk */
639 		RF_Malloc(raidPtr->recon_tracerecs, raidPtr->numCol * sizeof(RF_AccTraceEntry_t), (RF_AccTraceEntry_t *));
640 
641 		/* quiesce the array prior to starting recon.  this is needed
642 		 * to assure no nasty interactions with pending user writes.
643 		 * We need to do this before we change the disk or row status. */
644 		reconDesc->state = 1;
645 
646 		Dprintf("RECON: begin request suspend\n");
647 		retcode = rf_SuspendNewRequestsAndWait(raidPtr);
648 		Dprintf("RECON: end request suspend\n");
649 		rf_StartUserStats(raidPtr);	/* zero out the stats kept on
650 						 * user accs */
651 
652 		/* fall through to state 1 */
653 
654 	case 1:
655 
656 		RF_LOCK_MUTEX(raidPtr->mutex);
657 
658 		/* create the reconstruction control pointer and install it in
659 		 * the right slot */
660 		raidPtr->reconControl[row] = rf_MakeReconControl(reconDesc, row, col, srow, scol);
661 		mapPtr = raidPtr->reconControl[row]->reconMap;
662 		raidPtr->status[row] = rf_rs_reconstructing;
663 		raidPtr->Disks[row][col].status = rf_ds_reconstructing;
664 		raidPtr->Disks[row][col].spareRow = srow;
665 		raidPtr->Disks[row][col].spareCol = scol;
666 
667 		RF_UNLOCK_MUTEX(raidPtr->mutex);
668 
669 		RF_GETTIME(raidPtr->reconControl[row]->starttime);
670 
671 		/* now start up the actual reconstruction: issue a read for
672 		 * each surviving disk */
673 
674 		reconDesc->numDisksDone = 0;
675 		for (i = 0; i < raidPtr->numCol; i++) {
676 			if (i != col) {
677 				/* find and issue the next I/O on the
678 				 * indicated disk */
679 				if (IssueNextReadRequest(raidPtr, row, i)) {
680 					Dprintf2("RECON: done issuing for r%d c%d\n", row, i);
681 					reconDesc->numDisksDone++;
682 				}
683 			}
684 		}
685 
686 	case 2:
687 		Dprintf("RECON: resume requests\n");
688 		rf_ResumeNewRequests(raidPtr);
689 
690 
691 		reconDesc->state = 3;
692 
693 	case 3:
694 
695 		/* process reconstruction events until all disks report that
696 		 * they've completed all work */
697 		mapPtr = raidPtr->reconControl[row]->reconMap;
698 
699 
700 
701 		while (reconDesc->numDisksDone < raidPtr->numCol - 1) {
702 
703 			event = rf_GetNextReconEvent(reconDesc, row, (void (*) (void *)) rf_ContinueReconstructFailedDisk, reconDesc);
704 			RF_ASSERT(event);
705 
706 			if (ProcessReconEvent(raidPtr, row, event))
707 				reconDesc->numDisksDone++;
708 			raidPtr->reconControl[row]->percentComplete = 100 - (rf_UnitsLeftToReconstruct(mapPtr) * 100 / mapPtr->totalRUs);
709 			if (rf_prReconSched) {
710 				rf_PrintReconSchedule(raidPtr->reconControl[row]->reconMap, &(raidPtr->reconControl[row]->starttime));
711 			}
712 		}
713 
714 
715 
716 		reconDesc->state = 4;
717 
718 
719 	case 4:
720 		mapPtr = raidPtr->reconControl[row]->reconMap;
721 		if (rf_reconDebug) {
722 			printf("RECON: all reads completed\n");
723 		}
724 		/* at this point all the reads have completed.  We now wait
725 		 * for any pending writes to complete, and then we're done */
726 
727 		while (rf_UnitsLeftToReconstruct(raidPtr->reconControl[row]->reconMap) > 0) {
728 
729 			event = rf_GetNextReconEvent(reconDesc, row, (void (*) (void *)) rf_ContinueReconstructFailedDisk, reconDesc);
730 			RF_ASSERT(event);
731 
732 			(void) ProcessReconEvent(raidPtr, row, event);	/* ignore return code */
733 			raidPtr->reconControl[row]->percentComplete = 100 - (rf_UnitsLeftToReconstruct(mapPtr) * 100 / mapPtr->totalRUs);
734 			if (rf_prReconSched) {
735 				rf_PrintReconSchedule(raidPtr->reconControl[row]->reconMap, &(raidPtr->reconControl[row]->starttime));
736 			}
737 		}
738 		reconDesc->state = 5;
739 
740 	case 5:
741 		/* Success:  mark the dead disk as reconstructed.  We quiesce
742 		 * the array here to assure no nasty interactions with pending
743 		 * user accesses when we free up the psstatus structure as
744 		 * part of FreeReconControl() */
745 
746 		reconDesc->state = 6;
747 
748 		retcode = rf_SuspendNewRequestsAndWait(raidPtr);
749 		rf_StopUserStats(raidPtr);
750 		rf_PrintUserStats(raidPtr);	/* print out the stats on user
751 						 * accs accumulated during
752 						 * recon */
753 
754 		/* fall through to state 6 */
755 	case 6:
756 
757 
758 
759 		RF_LOCK_MUTEX(raidPtr->mutex);
760 		raidPtr->numFailures--;
761 		ds = (raidPtr->Layout.map->flags & RF_DISTRIBUTE_SPARE);
762 		raidPtr->Disks[row][col].status = (ds) ? rf_ds_dist_spared : rf_ds_spared;
763 		raidPtr->status[row] = (ds) ? rf_rs_reconfigured : rf_rs_optimal;
764 		RF_UNLOCK_MUTEX(raidPtr->mutex);
765 		RF_GETTIME(etime);
766 		RF_TIMEVAL_DIFF(&(raidPtr->reconControl[row]->starttime), &etime, &elpsd);
767 
768 		/* XXX -- why is state 7 different from state 6 if there is no
769 		 * return() here? -- XXX Note that I set elpsd above & use it
770 		 * below, so if you put a return here you'll have to fix this.
771 		 * (also, FreeReconControl is called below) */
772 
773 	case 7:
774 
775 		rf_ResumeNewRequests(raidPtr);
776 
777 		printf("Reconstruction of disk at row %d col %d completed\n",
778 		       row, col);
779 		xor_s = raidPtr->accumXorTimeUs / 1000000;
780 		xor_resid_us = raidPtr->accumXorTimeUs % 1000000;
781 		printf("Recon time was %d.%06d seconds, accumulated XOR time was %ld us (%ld.%06ld)\n",
782 		    (int) elpsd.tv_sec, (int) elpsd.tv_usec, raidPtr->accumXorTimeUs, xor_s, xor_resid_us);
783 		printf("  (start time %d sec %d usec, end time %d sec %d usec)\n",
784 		    (int) raidPtr->reconControl[row]->starttime.tv_sec,
785 		    (int) raidPtr->reconControl[row]->starttime.tv_usec,
786 		    (int) etime.tv_sec, (int) etime.tv_usec);
787 
788 #if RF_RECON_STATS > 0
789 		printf("Total head-sep stall count was %d\n",
790 		    (int) reconDesc->hsStallCount);
791 #endif				/* RF_RECON_STATS > 0 */
792 		rf_FreeReconControl(raidPtr, row);
793 		RF_Free(raidPtr->recon_tracerecs, raidPtr->numCol * sizeof(RF_AccTraceEntry_t));
794 		FreeReconDesc(reconDesc);
795 
796 	}
797 
798 	SignalReconDone(raidPtr);
799 	return (0);
800 }
801 /*****************************************************************************
802  * do the right thing upon each reconstruction event.
803  * returns nonzero if and only if there is nothing left unread on the
804  * indicated disk
805  *****************************************************************************/
806 static int
807 ProcessReconEvent(raidPtr, frow, event)
808 	RF_Raid_t *raidPtr;
809 	RF_RowCol_t frow;
810 	RF_ReconEvent_t *event;
811 {
812 	int     retcode = 0, submitblocked;
813 	RF_ReconBuffer_t *rbuf;
814 	RF_SectorCount_t sectorsPerRU;
815 
816 	Dprintf1("RECON: ProcessReconEvent type %d\n", event->type);
817 	switch (event->type) {
818 
819 		/* a read I/O has completed */
820 	case RF_REVENT_READDONE:
821 		rbuf = raidPtr->reconControl[frow]->perDiskInfo[event->col].rbuf;
822 		Dprintf3("RECON: READDONE EVENT: row %d col %d psid %ld\n",
823 		    frow, event->col, rbuf->parityStripeID);
824 		Dprintf7("RECON: done read  psid %ld buf %lx  %02x %02x %02x %02x %02x\n",
825 		    rbuf->parityStripeID, rbuf->buffer, rbuf->buffer[0] & 0xff, rbuf->buffer[1] & 0xff,
826 		    rbuf->buffer[2] & 0xff, rbuf->buffer[3] & 0xff, rbuf->buffer[4] & 0xff);
827 		rf_FreeDiskQueueData((RF_DiskQueueData_t *) rbuf->arg);
828 		submitblocked = rf_SubmitReconBuffer(rbuf, 0, 0);
829 		Dprintf1("RECON: submitblocked=%d\n", submitblocked);
830 		if (!submitblocked)
831 			retcode = IssueNextReadRequest(raidPtr, frow, event->col);
832 		break;
833 
834 		/* a write I/O has completed */
835 	case RF_REVENT_WRITEDONE:
836 		if (rf_floatingRbufDebug) {
837 			rf_CheckFloatingRbufCount(raidPtr, 1);
838 		}
839 		sectorsPerRU = raidPtr->Layout.sectorsPerStripeUnit * raidPtr->Layout.SUsPerRU;
840 		rbuf = (RF_ReconBuffer_t *) event->arg;
841 		rf_FreeDiskQueueData((RF_DiskQueueData_t *) rbuf->arg);
842 		Dprintf3("RECON: WRITEDONE EVENT: psid %d ru %d (%d %% complete)\n",
843 		    rbuf->parityStripeID, rbuf->which_ru, raidPtr->reconControl[frow]->percentComplete);
844 		rf_ReconMapUpdate(raidPtr, raidPtr->reconControl[frow]->reconMap,
845 		    rbuf->failedDiskSectorOffset, rbuf->failedDiskSectorOffset + sectorsPerRU - 1);
846 		rf_RemoveFromActiveReconTable(raidPtr, frow, rbuf->parityStripeID, rbuf->which_ru);
847 
848 		if (rbuf->type == RF_RBUF_TYPE_FLOATING) {
849 			RF_LOCK_MUTEX(raidPtr->reconControl[frow]->rb_mutex);
850 			raidPtr->numFullReconBuffers--;
851 			rf_ReleaseFloatingReconBuffer(raidPtr, frow, rbuf);
852 			RF_UNLOCK_MUTEX(raidPtr->reconControl[frow]->rb_mutex);
853 		} else
854 			if (rbuf->type == RF_RBUF_TYPE_FORCED)
855 				rf_FreeReconBuffer(rbuf);
856 			else
857 				RF_ASSERT(0);
858 		break;
859 
860 	case RF_REVENT_BUFCLEAR:	/* A buffer-stall condition has been
861 					 * cleared */
862 		Dprintf2("RECON: BUFCLEAR EVENT: row %d col %d\n", frow, event->col);
863 		submitblocked = rf_SubmitReconBuffer(raidPtr->reconControl[frow]->perDiskInfo[event->col].rbuf, 0, (int) (long) event->arg);
864 		RF_ASSERT(!submitblocked);	/* we wouldn't have gotten the
865 						 * BUFCLEAR event if we
866 						 * couldn't submit */
867 		retcode = IssueNextReadRequest(raidPtr, frow, event->col);
868 		break;
869 
870 	case RF_REVENT_BLOCKCLEAR:	/* A user-write reconstruction
871 					 * blockage has been cleared */
872 		DDprintf2("RECON: BLOCKCLEAR EVENT: row %d col %d\n", frow, event->col);
873 		retcode = TryToRead(raidPtr, frow, event->col);
874 		break;
875 
876 	case RF_REVENT_HEADSEPCLEAR:	/* A max-head-separation
877 					 * reconstruction blockage has been
878 					 * cleared */
879 		Dprintf2("RECON: HEADSEPCLEAR EVENT: row %d col %d\n", frow, event->col);
880 		retcode = TryToRead(raidPtr, frow, event->col);
881 		break;
882 
883 		/* a buffer has become ready to write */
884 	case RF_REVENT_BUFREADY:
885 		Dprintf2("RECON: BUFREADY EVENT: row %d col %d\n", frow, event->col);
886 		retcode = IssueNextWriteRequest(raidPtr, frow);
887 		if (rf_floatingRbufDebug) {
888 			rf_CheckFloatingRbufCount(raidPtr, 1);
889 		}
890 		break;
891 
892 		/* we need to skip the current RU entirely because it got
893 		 * recon'd while we were waiting for something else to happen */
894 	case RF_REVENT_SKIP:
895 		DDprintf2("RECON: SKIP EVENT: row %d col %d\n", frow, event->col);
896 		retcode = IssueNextReadRequest(raidPtr, frow, event->col);
897 		break;
898 
899 		/* a forced-reconstruction read access has completed.  Just
900 		 * submit the buffer */
901 	case RF_REVENT_FORCEDREADDONE:
902 		rbuf = (RF_ReconBuffer_t *) event->arg;
903 		rf_FreeDiskQueueData((RF_DiskQueueData_t *) rbuf->arg);
904 		DDprintf2("RECON: FORCEDREADDONE EVENT: row %d col %d\n", frow, event->col);
905 		submitblocked = rf_SubmitReconBuffer(rbuf, 1, 0);
906 		RF_ASSERT(!submitblocked);
907 		break;
908 
909 	default:
910 		RF_PANIC();
911 	}
912 	rf_FreeReconEventDesc(event);
913 	return (retcode);
914 }
915 /*****************************************************************************
916  *
917  * find the next thing that's needed on the indicated disk, and issue
918  * a read request for it.  We assume that the reconstruction buffer
919  * associated with this process is free to receive the data.  If
920  * reconstruction is blocked on the indicated RU, we issue a
921  * blockage-release request instead of a physical disk read request.
922  * If the current disk gets too far ahead of the others, we issue a
923  * head-separation wait request and return.
924  *
925  * ctrl->{ru_count, curPSID, diskOffset} and
926  * rbuf->failedDiskSectorOffset are maintained to point the the unit
927  * we're currently accessing.  Note that this deviates from the
928  * standard C idiom of having counters point to the next thing to be
929  * accessed.  This allows us to easily retry when we're blocked by
930  * head separation or reconstruction-blockage events.
931  *
932  * returns nonzero if and only if there is nothing left unread on the
933  * indicated disk
934  *
935  *****************************************************************************/
936 static int
937 IssueNextReadRequest(raidPtr, row, col)
938 	RF_Raid_t *raidPtr;
939 	RF_RowCol_t row;
940 	RF_RowCol_t col;
941 {
942 	RF_PerDiskReconCtrl_t *ctrl = &raidPtr->reconControl[row]->perDiskInfo[col];
943 	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
944 	RF_ReconBuffer_t *rbuf = ctrl->rbuf;
945 	RF_ReconUnitCount_t RUsPerPU = layoutPtr->SUsPerPU / layoutPtr->SUsPerRU;
946 	RF_SectorCount_t sectorsPerRU = layoutPtr->sectorsPerStripeUnit * layoutPtr->SUsPerRU;
947 	int     do_new_check = 0, retcode = 0, status;
948 
949 	/* if we are currently the slowest disk, mark that we have to do a new
950 	 * check */
951 	if (ctrl->headSepCounter <= raidPtr->reconControl[row]->minHeadSepCounter)
952 		do_new_check = 1;
953 
954 	while (1) {
955 
956 		ctrl->ru_count++;
957 		if (ctrl->ru_count < RUsPerPU) {
958 			ctrl->diskOffset += sectorsPerRU;
959 			rbuf->failedDiskSectorOffset += sectorsPerRU;
960 		} else {
961 			ctrl->curPSID++;
962 			ctrl->ru_count = 0;
963 			/* code left over from when head-sep was based on
964 			 * parity stripe id */
965 			if (ctrl->curPSID >= raidPtr->reconControl[row]->lastPSID) {
966 				CheckForNewMinHeadSep(raidPtr, row, ++(ctrl->headSepCounter));
967 				return (1);	/* finito! */
968 			}
969 			/* find the disk offsets of the start of the parity
970 			 * stripe on both the current disk and the failed
971 			 * disk. skip this entire parity stripe if either disk
972 			 * does not appear in the indicated PS */
973 			status = ComputePSDiskOffsets(raidPtr, ctrl->curPSID, row, col, &ctrl->diskOffset, &rbuf->failedDiskSectorOffset,
974 			    &rbuf->spRow, &rbuf->spCol, &rbuf->spOffset);
975 			if (status) {
976 				ctrl->ru_count = RUsPerPU - 1;
977 				continue;
978 			}
979 		}
980 		rbuf->which_ru = ctrl->ru_count;
981 
982 		/* skip this RU if it's already been reconstructed */
983 		if (rf_CheckRUReconstructed(raidPtr->reconControl[row]->reconMap, rbuf->failedDiskSectorOffset)) {
984 			Dprintf2("Skipping psid %ld ru %d: already reconstructed\n", ctrl->curPSID, ctrl->ru_count);
985 			continue;
986 		}
987 		break;
988 	}
989 	ctrl->headSepCounter++;
990 	if (do_new_check)
991 		CheckForNewMinHeadSep(raidPtr, row, ctrl->headSepCounter);	/* update min if needed */
992 
993 
994 	/* at this point, we have definitely decided what to do, and we have
995 	 * only to see if we can actually do it now */
996 	rbuf->parityStripeID = ctrl->curPSID;
997 	rbuf->which_ru = ctrl->ru_count;
998 	bzero((char *) &raidPtr->recon_tracerecs[col], sizeof(raidPtr->recon_tracerecs[col]));
999 	raidPtr->recon_tracerecs[col].reconacc = 1;
1000 	RF_ETIMER_START(raidPtr->recon_tracerecs[col].recon_timer);
1001 	retcode = TryToRead(raidPtr, row, col);
1002 	return (retcode);
1003 }
1004 
1005 /*
1006  * tries to issue the next read on the indicated disk.  We may be
1007  * blocked by (a) the heads being too far apart, or (b) recon on the
1008  * indicated RU being blocked due to a write by a user thread.  In
1009  * this case, we issue a head-sep or blockage wait request, which will
1010  * cause this same routine to be invoked again later when the blockage
1011  * has cleared.
1012  */
1013 
1014 static int
1015 TryToRead(raidPtr, row, col)
1016 	RF_Raid_t *raidPtr;
1017 	RF_RowCol_t row;
1018 	RF_RowCol_t col;
1019 {
1020 	RF_PerDiskReconCtrl_t *ctrl = &raidPtr->reconControl[row]->perDiskInfo[col];
1021 	RF_SectorCount_t sectorsPerRU = raidPtr->Layout.sectorsPerStripeUnit * raidPtr->Layout.SUsPerRU;
1022 	RF_StripeNum_t psid = ctrl->curPSID;
1023 	RF_ReconUnitNum_t which_ru = ctrl->ru_count;
1024 	RF_DiskQueueData_t *req;
1025 	int     status, created = 0;
1026 	RF_ReconParityStripeStatus_t *pssPtr;
1027 
1028 	/* if the current disk is too far ahead of the others, issue a
1029 	 * head-separation wait and return */
1030 	if (CheckHeadSeparation(raidPtr, ctrl, row, col, ctrl->headSepCounter, which_ru))
1031 		return (0);
1032 	RF_LOCK_PSS_MUTEX(raidPtr, row, psid);
1033 	pssPtr = rf_LookupRUStatus(raidPtr, raidPtr->reconControl[row]->pssTable, psid, which_ru, RF_PSS_CREATE, &created);
1034 
1035 	/* if recon is blocked on the indicated parity stripe, issue a
1036 	 * block-wait request and return. this also must mark the indicated RU
1037 	 * in the stripe as under reconstruction if not blocked. */
1038 	status = CheckForcedOrBlockedReconstruction(raidPtr, pssPtr, ctrl, row, col, psid, which_ru);
1039 	if (status == RF_PSS_RECON_BLOCKED) {
1040 		Dprintf2("RECON: Stalling psid %ld ru %d: recon blocked\n", psid, which_ru);
1041 		goto out;
1042 	} else
1043 		if (status == RF_PSS_FORCED_ON_WRITE) {
1044 			rf_CauseReconEvent(raidPtr, row, col, NULL, RF_REVENT_SKIP);
1045 			goto out;
1046 		}
1047 	/* make one last check to be sure that the indicated RU didn't get
1048 	 * reconstructed while we were waiting for something else to happen.
1049 	 * This is unfortunate in that it causes us to make this check twice
1050 	 * in the normal case.  Might want to make some attempt to re-work
1051 	 * this so that we only do this check if we've definitely blocked on
1052 	 * one of the above checks.  When this condition is detected, we may
1053 	 * have just created a bogus status entry, which we need to delete. */
1054 	if (rf_CheckRUReconstructed(raidPtr->reconControl[row]->reconMap, ctrl->rbuf->failedDiskSectorOffset)) {
1055 		Dprintf2("RECON: Skipping psid %ld ru %d: prior recon after stall\n", psid, which_ru);
1056 		if (created)
1057 			rf_PSStatusDelete(raidPtr, raidPtr->reconControl[row]->pssTable, pssPtr);
1058 		rf_CauseReconEvent(raidPtr, row, col, NULL, RF_REVENT_SKIP);
1059 		goto out;
1060 	}
1061 	/* found something to read.  issue the I/O */
1062 	Dprintf5("RECON: Read for psid %ld on row %d col %d offset %ld buf %lx\n",
1063 	    psid, row, col, ctrl->diskOffset, ctrl->rbuf->buffer);
1064 	RF_ETIMER_STOP(raidPtr->recon_tracerecs[col].recon_timer);
1065 	RF_ETIMER_EVAL(raidPtr->recon_tracerecs[col].recon_timer);
1066 	raidPtr->recon_tracerecs[col].specific.recon.recon_start_to_fetch_us =
1067 	    RF_ETIMER_VAL_US(raidPtr->recon_tracerecs[col].recon_timer);
1068 	RF_ETIMER_START(raidPtr->recon_tracerecs[col].recon_timer);
1069 
1070 	/* should be ok to use a NULL proc pointer here, all the bufs we use
1071 	 * should be in kernel space */
1072 	req = rf_CreateDiskQueueData(RF_IO_TYPE_READ, ctrl->diskOffset, sectorsPerRU, ctrl->rbuf->buffer, psid, which_ru,
1073 	    ReconReadDoneProc, (void *) ctrl, NULL, &raidPtr->recon_tracerecs[col], (void *) raidPtr, 0, NULL);
1074 
1075 	RF_ASSERT(req);		/* XXX -- fix this -- XXX */
1076 
1077 	ctrl->rbuf->arg = (void *) req;
1078 	rf_DiskIOEnqueue(&raidPtr->Queues[row][col], req, RF_IO_RECON_PRIORITY);
1079 	pssPtr->issued[col] = 1;
1080 
1081 out:
1082 	RF_UNLOCK_PSS_MUTEX(raidPtr, row, psid);
1083 	return (0);
1084 }
1085 
1086 
1087 /*
1088  * given a parity stripe ID, we want to find out whether both the
1089  * current disk and the failed disk exist in that parity stripe.  If
1090  * not, we want to skip this whole PS.  If so, we want to find the
1091  * disk offset of the start of the PS on both the current disk and the
1092  * failed disk.
1093  *
1094  * this works by getting a list of disks comprising the indicated
1095  * parity stripe, and searching the list for the current and failed
1096  * disks.  Once we've decided they both exist in the parity stripe, we
1097  * need to decide whether each is data or parity, so that we'll know
1098  * which mapping function to call to get the corresponding disk
1099  * offsets.
1100  *
1101  * this is kind of unpleasant, but doing it this way allows the
1102  * reconstruction code to use parity stripe IDs rather than physical
1103  * disks address to march through the failed disk, which greatly
1104  * simplifies a lot of code, as well as eliminating the need for a
1105  * reverse-mapping function.  I also think it will execute faster,
1106  * since the calls to the mapping module are kept to a minimum.
1107  *
1108  * ASSUMES THAT THE STRIPE IDENTIFIER IDENTIFIES THE DISKS COMPRISING
1109  * THE STRIPE IN THE CORRECT ORDER */
1110 
1111 
1112 static int
1113 ComputePSDiskOffsets(
1114     RF_Raid_t * raidPtr,	/* raid descriptor */
1115     RF_StripeNum_t psid,	/* parity stripe identifier */
1116     RF_RowCol_t row,		/* row and column of disk to find the offsets
1117 				 * for */
1118     RF_RowCol_t col,
1119     RF_SectorNum_t * outDiskOffset,
1120     RF_SectorNum_t * outFailedDiskSectorOffset,
1121     RF_RowCol_t * spRow,	/* OUT: row,col of spare unit for failed unit */
1122     RF_RowCol_t * spCol,
1123     RF_SectorNum_t * spOffset)
1124 {				/* OUT: offset into disk containing spare unit */
1125 	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
1126 	RF_RowCol_t fcol = raidPtr->reconControl[row]->fcol;
1127 	RF_RaidAddr_t sosRaidAddress;	/* start-of-stripe */
1128 	RF_RowCol_t *diskids;
1129 	u_int   i, j, k, i_offset, j_offset;
1130 	RF_RowCol_t prow, pcol;
1131 	int     testcol, testrow;
1132 	RF_RowCol_t stripe;
1133 	RF_SectorNum_t poffset;
1134 	char    i_is_parity = 0, j_is_parity = 0;
1135 	RF_RowCol_t stripeWidth = layoutPtr->numDataCol + layoutPtr->numParityCol;
1136 
1137 	/* get a listing of the disks comprising that stripe */
1138 	sosRaidAddress = rf_ParityStripeIDToRaidAddress(layoutPtr, psid);
1139 	(layoutPtr->map->IdentifyStripe) (raidPtr, sosRaidAddress, &diskids, &stripe);
1140 	RF_ASSERT(diskids);
1141 
1142 	/* reject this entire parity stripe if it does not contain the
1143 	 * indicated disk or it does not contain the failed disk */
1144 	if (row != stripe)
1145 		goto skipit;
1146 	for (i = 0; i < stripeWidth; i++) {
1147 		if (col == diskids[i])
1148 			break;
1149 	}
1150 	if (i == stripeWidth)
1151 		goto skipit;
1152 	for (j = 0; j < stripeWidth; j++) {
1153 		if (fcol == diskids[j])
1154 			break;
1155 	}
1156 	if (j == stripeWidth) {
1157 		goto skipit;
1158 	}
1159 	/* find out which disk the parity is on */
1160 	(layoutPtr->map->MapParity) (raidPtr, sosRaidAddress, &prow, &pcol, &poffset, RF_DONT_REMAP);
1161 
1162 	/* find out if either the current RU or the failed RU is parity */
1163 	/* also, if the parity occurs in this stripe prior to the data and/or
1164 	 * failed col, we need to decrement i and/or j */
1165 	for (k = 0; k < stripeWidth; k++)
1166 		if (diskids[k] == pcol)
1167 			break;
1168 	RF_ASSERT(k < stripeWidth);
1169 	i_offset = i;
1170 	j_offset = j;
1171 	if (k < i)
1172 		i_offset--;
1173 	else
1174 		if (k == i) {
1175 			i_is_parity = 1;
1176 			i_offset = 0;
1177 		}		/* set offsets to zero to disable multiply
1178 				 * below */
1179 	if (k < j)
1180 		j_offset--;
1181 	else
1182 		if (k == j) {
1183 			j_is_parity = 1;
1184 			j_offset = 0;
1185 		}
1186 	/* at this point, [ij]_is_parity tells us whether the [current,failed]
1187 	 * disk is parity at the start of this RU, and, if data, "[ij]_offset"
1188 	 * tells us how far into the stripe the [current,failed] disk is. */
1189 
1190 	/* call the mapping routine to get the offset into the current disk,
1191 	 * repeat for failed disk. */
1192 	if (i_is_parity)
1193 		layoutPtr->map->MapParity(raidPtr, sosRaidAddress + i_offset * layoutPtr->sectorsPerStripeUnit, &testrow, &testcol, outDiskOffset, RF_DONT_REMAP);
1194 	else
1195 		layoutPtr->map->MapSector(raidPtr, sosRaidAddress + i_offset * layoutPtr->sectorsPerStripeUnit, &testrow, &testcol, outDiskOffset, RF_DONT_REMAP);
1196 
1197 	RF_ASSERT(row == testrow && col == testcol);
1198 
1199 	if (j_is_parity)
1200 		layoutPtr->map->MapParity(raidPtr, sosRaidAddress + j_offset * layoutPtr->sectorsPerStripeUnit, &testrow, &testcol, outFailedDiskSectorOffset, RF_DONT_REMAP);
1201 	else
1202 		layoutPtr->map->MapSector(raidPtr, sosRaidAddress + j_offset * layoutPtr->sectorsPerStripeUnit, &testrow, &testcol, outFailedDiskSectorOffset, RF_DONT_REMAP);
1203 	RF_ASSERT(row == testrow && fcol == testcol);
1204 
1205 	/* now locate the spare unit for the failed unit */
1206 	if (layoutPtr->map->flags & RF_DISTRIBUTE_SPARE) {
1207 		if (j_is_parity)
1208 			layoutPtr->map->MapParity(raidPtr, sosRaidAddress + j_offset * layoutPtr->sectorsPerStripeUnit, spRow, spCol, spOffset, RF_REMAP);
1209 		else
1210 			layoutPtr->map->MapSector(raidPtr, sosRaidAddress + j_offset * layoutPtr->sectorsPerStripeUnit, spRow, spCol, spOffset, RF_REMAP);
1211 	} else {
1212 		*spRow = raidPtr->reconControl[row]->spareRow;
1213 		*spCol = raidPtr->reconControl[row]->spareCol;
1214 		*spOffset = *outFailedDiskSectorOffset;
1215 	}
1216 
1217 	return (0);
1218 
1219 skipit:
1220 	Dprintf3("RECON: Skipping psid %ld: nothing needed from r%d c%d\n",
1221 	    psid, row, col);
1222 	return (1);
1223 }
1224 /* this is called when a buffer has become ready to write to the replacement disk */
1225 static int
1226 IssueNextWriteRequest(raidPtr, row)
1227 	RF_Raid_t *raidPtr;
1228 	RF_RowCol_t row;
1229 {
1230 	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
1231 	RF_SectorCount_t sectorsPerRU = layoutPtr->sectorsPerStripeUnit * layoutPtr->SUsPerRU;
1232 	RF_RowCol_t fcol = raidPtr->reconControl[row]->fcol;
1233 	RF_ReconBuffer_t *rbuf;
1234 	RF_DiskQueueData_t *req;
1235 
1236 	rbuf = rf_GetFullReconBuffer(raidPtr->reconControl[row]);
1237 	RF_ASSERT(rbuf);	/* there must be one available, or we wouldn't
1238 				 * have gotten the event that sent us here */
1239 	RF_ASSERT(rbuf->pssPtr);
1240 
1241 	rbuf->pssPtr->writeRbuf = rbuf;
1242 	rbuf->pssPtr = NULL;
1243 
1244 	Dprintf7("RECON: New write (r %d c %d offs %d) for psid %ld ru %d (failed disk offset %ld) buf %lx\n",
1245 	    rbuf->spRow, rbuf->spCol, rbuf->spOffset, rbuf->parityStripeID,
1246 	    rbuf->which_ru, rbuf->failedDiskSectorOffset, rbuf->buffer);
1247 	Dprintf6("RECON: new write psid %ld   %02x %02x %02x %02x %02x\n",
1248 	    rbuf->parityStripeID, rbuf->buffer[0] & 0xff, rbuf->buffer[1] & 0xff,
1249 	    rbuf->buffer[2] & 0xff, rbuf->buffer[3] & 0xff, rbuf->buffer[4] & 0xff);
1250 
1251 	/* should be ok to use a NULL b_proc here b/c all addrs should be in
1252 	 * kernel space */
1253 	req = rf_CreateDiskQueueData(RF_IO_TYPE_WRITE, rbuf->spOffset,
1254 	    sectorsPerRU, rbuf->buffer,
1255 	    rbuf->parityStripeID, rbuf->which_ru,
1256 	    ReconWriteDoneProc, (void *) rbuf, NULL,
1257 	    &raidPtr->recon_tracerecs[fcol],
1258 	    (void *) raidPtr, 0, NULL);
1259 
1260 	RF_ASSERT(req);		/* XXX -- fix this -- XXX */
1261 
1262 	rbuf->arg = (void *) req;
1263 	rf_DiskIOEnqueue(&raidPtr->Queues[rbuf->spRow][rbuf->spCol], req, RF_IO_RECON_PRIORITY);
1264 
1265 	return (0);
1266 }
1267 
1268 /*
1269  * this gets called upon the completion of a reconstruction read
1270  * operation the arg is a pointer to the per-disk reconstruction
1271  * control structure for the process that just finished a read.
1272  *
1273  * called at interrupt context in the kernel, so don't do anything
1274  * illegal here.
1275  */
1276 static int
1277 ReconReadDoneProc(arg, status)
1278 	void   *arg;
1279 	int     status;
1280 {
1281 	RF_PerDiskReconCtrl_t *ctrl = (RF_PerDiskReconCtrl_t *) arg;
1282 	RF_Raid_t *raidPtr = ctrl->reconCtrl->reconDesc->raidPtr;
1283 
1284 	if (status) {
1285 		/*
1286 	         * XXX
1287 	         */
1288 		printf("Recon read failed!\n");
1289 		RF_PANIC();
1290 	}
1291 	RF_ETIMER_STOP(raidPtr->recon_tracerecs[ctrl->col].recon_timer);
1292 	RF_ETIMER_EVAL(raidPtr->recon_tracerecs[ctrl->col].recon_timer);
1293 	raidPtr->recon_tracerecs[ctrl->col].specific.recon.recon_fetch_to_return_us =
1294 	    RF_ETIMER_VAL_US(raidPtr->recon_tracerecs[ctrl->col].recon_timer);
1295 	RF_ETIMER_START(raidPtr->recon_tracerecs[ctrl->col].recon_timer);
1296 
1297 	rf_CauseReconEvent(raidPtr, ctrl->row, ctrl->col, NULL, RF_REVENT_READDONE);
1298 	return (0);
1299 }
1300 /* this gets called upon the completion of a reconstruction write operation.
1301  * the arg is a pointer to the rbuf that was just written
1302  *
1303  * called at interrupt context in the kernel, so don't do anything illegal here.
1304  */
1305 static int
1306 ReconWriteDoneProc(arg, status)
1307 	void   *arg;
1308 	int     status;
1309 {
1310 	RF_ReconBuffer_t *rbuf = (RF_ReconBuffer_t *) arg;
1311 
1312 	Dprintf2("Reconstruction completed on psid %ld ru %d\n", rbuf->parityStripeID, rbuf->which_ru);
1313 	if (status) {
1314 		printf("Recon write failed!\n");	/* fprintf(stderr,"Recon
1315 							 * write failed!\n"); */
1316 		RF_PANIC();
1317 	}
1318 	rf_CauseReconEvent((RF_Raid_t *) rbuf->raidPtr, rbuf->row, rbuf->col, arg, RF_REVENT_WRITEDONE);
1319 	return (0);
1320 }
1321 
1322 
1323 /*
1324  * computes a new minimum head sep, and wakes up anyone who needs to
1325  * be woken as a result
1326  */
1327 static void
1328 CheckForNewMinHeadSep(raidPtr, row, hsCtr)
1329 	RF_Raid_t *raidPtr;
1330 	RF_RowCol_t row;
1331 	RF_HeadSepLimit_t hsCtr;
1332 {
1333 	RF_ReconCtrl_t *reconCtrlPtr = raidPtr->reconControl[row];
1334 	RF_HeadSepLimit_t new_min;
1335 	RF_RowCol_t i;
1336 	RF_CallbackDesc_t *p;
1337 	RF_ASSERT(hsCtr >= reconCtrlPtr->minHeadSepCounter);	/* from the definition
1338 								 * of a minimum */
1339 
1340 
1341 	RF_LOCK_MUTEX(reconCtrlPtr->rb_mutex);
1342 
1343 	new_min = ~(1L << (8 * sizeof(long) - 1));	/* 0x7FFF....FFF */
1344 	for (i = 0; i < raidPtr->numCol; i++)
1345 		if (i != reconCtrlPtr->fcol) {
1346 			if (reconCtrlPtr->perDiskInfo[i].headSepCounter < new_min)
1347 				new_min = reconCtrlPtr->perDiskInfo[i].headSepCounter;
1348 		}
1349 	/* set the new minimum and wake up anyone who can now run again */
1350 	if (new_min != reconCtrlPtr->minHeadSepCounter) {
1351 		reconCtrlPtr->minHeadSepCounter = new_min;
1352 		Dprintf1("RECON:  new min head pos counter val is %ld\n", new_min);
1353 		while (reconCtrlPtr->headSepCBList) {
1354 			if (reconCtrlPtr->headSepCBList->callbackArg.v > new_min)
1355 				break;
1356 			p = reconCtrlPtr->headSepCBList;
1357 			reconCtrlPtr->headSepCBList = p->next;
1358 			p->next = NULL;
1359 			rf_CauseReconEvent(raidPtr, p->row, p->col, NULL, RF_REVENT_HEADSEPCLEAR);
1360 			rf_FreeCallbackDesc(p);
1361 		}
1362 
1363 	}
1364 	RF_UNLOCK_MUTEX(reconCtrlPtr->rb_mutex);
1365 }
1366 
1367 /*
1368  * checks to see that the maximum head separation will not be violated
1369  * if we initiate a reconstruction I/O on the indicated disk.
1370  * Limiting the maximum head separation between two disks eliminates
1371  * the nasty buffer-stall conditions that occur when one disk races
1372  * ahead of the others and consumes all of the floating recon buffers.
1373  * This code is complex and unpleasant but it's necessary to avoid
1374  * some very nasty, albeit fairly rare, reconstruction behavior.
1375  *
1376  * returns non-zero if and only if we have to stop working on the
1377  * indicated disk due to a head-separation delay.
1378  */
1379 static int
1380 CheckHeadSeparation(
1381     RF_Raid_t * raidPtr,
1382     RF_PerDiskReconCtrl_t * ctrl,
1383     RF_RowCol_t row,
1384     RF_RowCol_t col,
1385     RF_HeadSepLimit_t hsCtr,
1386     RF_ReconUnitNum_t which_ru)
1387 {
1388 	RF_ReconCtrl_t *reconCtrlPtr = raidPtr->reconControl[row];
1389 	RF_CallbackDesc_t *cb, *p, *pt;
1390 	int     retval = 0;
1391 
1392 	/* if we're too far ahead of the slowest disk, stop working on this
1393 	 * disk until the slower ones catch up.  We do this by scheduling a
1394 	 * wakeup callback for the time when the slowest disk has caught up.
1395 	 * We define "caught up" with 20% hysteresis, i.e. the head separation
1396 	 * must have fallen to at most 80% of the max allowable head
1397 	 * separation before we'll wake up.
1398 	 *
1399 	 */
1400 	RF_LOCK_MUTEX(reconCtrlPtr->rb_mutex);
1401 	if ((raidPtr->headSepLimit >= 0) &&
1402 	    ((ctrl->headSepCounter - reconCtrlPtr->minHeadSepCounter) > raidPtr->headSepLimit)) {
1403 		Dprintf6("raid%d: RECON: head sep stall: row %d col %d hsCtr %ld minHSCtr %ld limit %ld\n",
1404 			 raidPtr->raidid, row, col, ctrl->headSepCounter,
1405 			 reconCtrlPtr->minHeadSepCounter,
1406 			 raidPtr->headSepLimit);
1407 		cb = rf_AllocCallbackDesc();
1408 		/* the minHeadSepCounter value we have to get to before we'll
1409 		 * wake up.  build in 20% hysteresis. */
1410 		cb->callbackArg.v = (ctrl->headSepCounter - raidPtr->headSepLimit + raidPtr->headSepLimit / 5);
1411 		cb->row = row;
1412 		cb->col = col;
1413 		cb->next = NULL;
1414 
1415 		/* insert this callback descriptor into the sorted list of
1416 		 * pending head-sep callbacks */
1417 		p = reconCtrlPtr->headSepCBList;
1418 		if (!p)
1419 			reconCtrlPtr->headSepCBList = cb;
1420 		else
1421 			if (cb->callbackArg.v < p->callbackArg.v) {
1422 				cb->next = reconCtrlPtr->headSepCBList;
1423 				reconCtrlPtr->headSepCBList = cb;
1424 			} else {
1425 				for (pt = p, p = p->next; p && (p->callbackArg.v < cb->callbackArg.v); pt = p, p = p->next);
1426 				cb->next = p;
1427 				pt->next = cb;
1428 			}
1429 		retval = 1;
1430 #if RF_RECON_STATS > 0
1431 		ctrl->reconCtrl->reconDesc->hsStallCount++;
1432 #endif				/* RF_RECON_STATS > 0 */
1433 	}
1434 	RF_UNLOCK_MUTEX(reconCtrlPtr->rb_mutex);
1435 
1436 	return (retval);
1437 }
1438 /*
1439  * checks to see if reconstruction has been either forced or blocked
1440  * by a user operation.  if forced, we skip this RU entirely.  else if
1441  * blocked, put ourselves on the wait list.  else return 0.
1442  *
1443  * ASSUMES THE PSS MUTEX IS LOCKED UPON ENTRY
1444  */
1445 static int
1446 CheckForcedOrBlockedReconstruction(
1447     RF_Raid_t * raidPtr,
1448     RF_ReconParityStripeStatus_t * pssPtr,
1449     RF_PerDiskReconCtrl_t * ctrl,
1450     RF_RowCol_t row,
1451     RF_RowCol_t col,
1452     RF_StripeNum_t psid,
1453     RF_ReconUnitNum_t which_ru)
1454 {
1455 	RF_CallbackDesc_t *cb;
1456 	int     retcode = 0;
1457 
1458 	if ((pssPtr->flags & RF_PSS_FORCED_ON_READ) || (pssPtr->flags & RF_PSS_FORCED_ON_WRITE))
1459 		retcode = RF_PSS_FORCED_ON_WRITE;
1460 	else
1461 		if (pssPtr->flags & RF_PSS_RECON_BLOCKED) {
1462 			Dprintf4("RECON: row %d col %d blocked at psid %ld ru %d\n", row, col, psid, which_ru);
1463 			cb = rf_AllocCallbackDesc();	/* append ourselves to
1464 							 * the blockage-wait
1465 							 * list */
1466 			cb->row = row;
1467 			cb->col = col;
1468 			cb->next = pssPtr->blockWaitList;
1469 			pssPtr->blockWaitList = cb;
1470 			retcode = RF_PSS_RECON_BLOCKED;
1471 		}
1472 	if (!retcode)
1473 		pssPtr->flags |= RF_PSS_UNDER_RECON;	/* mark this RU as under
1474 							 * reconstruction */
1475 
1476 	return (retcode);
1477 }
1478 /*
1479  * if reconstruction is currently ongoing for the indicated stripeID,
1480  * reconstruction is forced to completion and we return non-zero to
1481  * indicate that the caller must wait.  If not, then reconstruction is
1482  * blocked on the indicated stripe and the routine returns zero.  If
1483  * and only if we return non-zero, we'll cause the cbFunc to get
1484  * invoked with the cbArg when the reconstruction has completed.
1485  */
1486 int
1487 rf_ForceOrBlockRecon(raidPtr, asmap, cbFunc, cbArg)
1488 	RF_Raid_t *raidPtr;
1489 	RF_AccessStripeMap_t *asmap;
1490 	void    (*cbFunc) (RF_Raid_t *, void *);
1491 	void   *cbArg;
1492 {
1493 	RF_RowCol_t row = asmap->physInfo->row;	/* which row of the array
1494 						 * we're working on */
1495 	RF_StripeNum_t stripeID = asmap->stripeID;	/* the stripe ID we're
1496 							 * forcing recon on */
1497 	RF_SectorCount_t sectorsPerRU = raidPtr->Layout.sectorsPerStripeUnit * raidPtr->Layout.SUsPerRU;	/* num sects in one RU */
1498 	RF_ReconParityStripeStatus_t *pssPtr;	/* a pointer to the parity
1499 						 * stripe status structure */
1500 	RF_StripeNum_t psid;	/* parity stripe id */
1501 	RF_SectorNum_t offset, fd_offset;	/* disk offset, failed-disk
1502 						 * offset */
1503 	RF_RowCol_t *diskids;
1504 	RF_RowCol_t stripe;
1505 	RF_ReconUnitNum_t which_ru;	/* RU within parity stripe */
1506 	RF_RowCol_t fcol, diskno, i;
1507 	RF_ReconBuffer_t *new_rbuf;	/* ptr to newly allocated rbufs */
1508 	RF_DiskQueueData_t *req;/* disk I/O req to be enqueued */
1509 	RF_CallbackDesc_t *cb;
1510 	int     created = 0, nPromoted;
1511 
1512 	psid = rf_MapStripeIDToParityStripeID(&raidPtr->Layout, stripeID, &which_ru);
1513 
1514 	RF_LOCK_PSS_MUTEX(raidPtr, row, psid);
1515 
1516 	pssPtr = rf_LookupRUStatus(raidPtr, raidPtr->reconControl[row]->pssTable, psid, which_ru, RF_PSS_CREATE | RF_PSS_RECON_BLOCKED, &created);
1517 
1518 	/* if recon is not ongoing on this PS, just return */
1519 	if (!(pssPtr->flags & RF_PSS_UNDER_RECON)) {
1520 		RF_UNLOCK_PSS_MUTEX(raidPtr, row, psid);
1521 		return (0);
1522 	}
1523 	/* otherwise, we have to wait for reconstruction to complete on this
1524 	 * RU. */
1525 	/* In order to avoid waiting for a potentially large number of
1526 	 * low-priority accesses to complete, we force a normal-priority (i.e.
1527 	 * not low-priority) reconstruction on this RU. */
1528 	if (!(pssPtr->flags & RF_PSS_FORCED_ON_WRITE) && !(pssPtr->flags & RF_PSS_FORCED_ON_READ)) {
1529 		DDprintf1("Forcing recon on psid %ld\n", psid);
1530 		pssPtr->flags |= RF_PSS_FORCED_ON_WRITE;	/* mark this RU as under
1531 								 * forced recon */
1532 		pssPtr->flags &= ~RF_PSS_RECON_BLOCKED;	/* clear the blockage
1533 							 * that we just set */
1534 		fcol = raidPtr->reconControl[row]->fcol;
1535 
1536 		/* get a listing of the disks comprising the indicated stripe */
1537 		(raidPtr->Layout.map->IdentifyStripe) (raidPtr, asmap->raidAddress, &diskids, &stripe);
1538 		RF_ASSERT(row == stripe);
1539 
1540 		/* For previously issued reads, elevate them to normal
1541 		 * priority.  If the I/O has already completed, it won't be
1542 		 * found in the queue, and hence this will be a no-op. For
1543 		 * unissued reads, allocate buffers and issue new reads.  The
1544 		 * fact that we've set the FORCED bit means that the regular
1545 		 * recon procs will not re-issue these reqs */
1546 		for (i = 0; i < raidPtr->Layout.numDataCol + raidPtr->Layout.numParityCol; i++)
1547 			if ((diskno = diskids[i]) != fcol) {
1548 				if (pssPtr->issued[diskno]) {
1549 					nPromoted = rf_DiskIOPromote(&raidPtr->Queues[row][diskno], psid, which_ru);
1550 					if (rf_reconDebug && nPromoted)
1551 						printf("raid%d: promoted read from row %d col %d\n", raidPtr->raidid, row, diskno);
1552 				} else {
1553 					new_rbuf = rf_MakeReconBuffer(raidPtr, row, diskno, RF_RBUF_TYPE_FORCED);	/* create new buf */
1554 					ComputePSDiskOffsets(raidPtr, psid, row, diskno, &offset, &fd_offset,
1555 					    &new_rbuf->spRow, &new_rbuf->spCol, &new_rbuf->spOffset);	/* find offsets & spare
1556 													 * location */
1557 					new_rbuf->parityStripeID = psid;	/* fill in the buffer */
1558 					new_rbuf->which_ru = which_ru;
1559 					new_rbuf->failedDiskSectorOffset = fd_offset;
1560 					new_rbuf->priority = RF_IO_NORMAL_PRIORITY;
1561 
1562 					/* use NULL b_proc b/c all addrs
1563 					 * should be in kernel space */
1564 					req = rf_CreateDiskQueueData(RF_IO_TYPE_READ, offset + which_ru * sectorsPerRU, sectorsPerRU, new_rbuf->buffer,
1565 					    psid, which_ru, (int (*) (void *, int)) ForceReconReadDoneProc, (void *) new_rbuf, NULL,
1566 					    NULL, (void *) raidPtr, 0, NULL);
1567 
1568 					RF_ASSERT(req);	/* XXX -- fix this --
1569 							 * XXX */
1570 
1571 					new_rbuf->arg = req;
1572 					rf_DiskIOEnqueue(&raidPtr->Queues[row][diskno], req, RF_IO_NORMAL_PRIORITY);	/* enqueue the I/O */
1573 					Dprintf3("raid%d: Issued new read req on row %d col %d\n", raidPtr->raidid, row, diskno);
1574 				}
1575 			}
1576 		/* if the write is sitting in the disk queue, elevate its
1577 		 * priority */
1578 		if (rf_DiskIOPromote(&raidPtr->Queues[row][fcol], psid, which_ru))
1579 			printf("raid%d: promoted write to row %d col %d\n",
1580 			       raidPtr->raidid, row, fcol);
1581 	}
1582 	/* install a callback descriptor to be invoked when recon completes on
1583 	 * this parity stripe. */
1584 	cb = rf_AllocCallbackDesc();
1585 	/* XXX the following is bogus.. These functions don't really match!!
1586 	 * GO */
1587 	cb->callbackFunc = (void (*) (RF_CBParam_t)) cbFunc;
1588 	cb->callbackArg.p = (void *) cbArg;
1589 	cb->next = pssPtr->procWaitList;
1590 	pssPtr->procWaitList = cb;
1591 	DDprintf2("raid%d: Waiting for forced recon on psid %ld\n",
1592 		  raidPtr->raidid, psid);
1593 
1594 	RF_UNLOCK_PSS_MUTEX(raidPtr, row, psid);
1595 	return (1);
1596 }
1597 /* called upon the completion of a forced reconstruction read.
1598  * all we do is schedule the FORCEDREADONE event.
1599  * called at interrupt context in the kernel, so don't do anything illegal here.
1600  */
1601 static void
1602 ForceReconReadDoneProc(arg, status)
1603 	void   *arg;
1604 	int     status;
1605 {
1606 	RF_ReconBuffer_t *rbuf = arg;
1607 
1608 	if (status) {
1609 		printf("Forced recon read failed!\n");	/* fprintf(stderr,"Forced
1610 							 *  recon read
1611 							 * failed!\n"); */
1612 		RF_PANIC();
1613 	}
1614 	rf_CauseReconEvent((RF_Raid_t *) rbuf->raidPtr, rbuf->row, rbuf->col, (void *) rbuf, RF_REVENT_FORCEDREADDONE);
1615 }
1616 /* releases a block on the reconstruction of the indicated stripe */
1617 int
1618 rf_UnblockRecon(raidPtr, asmap)
1619 	RF_Raid_t *raidPtr;
1620 	RF_AccessStripeMap_t *asmap;
1621 {
1622 	RF_RowCol_t row = asmap->origRow;
1623 	RF_StripeNum_t stripeID = asmap->stripeID;
1624 	RF_ReconParityStripeStatus_t *pssPtr;
1625 	RF_ReconUnitNum_t which_ru;
1626 	RF_StripeNum_t psid;
1627 	int     created = 0;
1628 	RF_CallbackDesc_t *cb;
1629 
1630 	psid = rf_MapStripeIDToParityStripeID(&raidPtr->Layout, stripeID, &which_ru);
1631 	RF_LOCK_PSS_MUTEX(raidPtr, row, psid);
1632 	pssPtr = rf_LookupRUStatus(raidPtr, raidPtr->reconControl[row]->pssTable, psid, which_ru, RF_PSS_NONE, &created);
1633 
1634 	/* When recon is forced, the pss desc can get deleted before we get
1635 	 * back to unblock recon. But, this can _only_ happen when recon is
1636 	 * forced. It would be good to put some kind of sanity check here, but
1637 	 * how to decide if recon was just forced or not? */
1638 	if (!pssPtr) {
1639 		/* printf("Warning: no pss descriptor upon unblock on psid %ld
1640 		 * RU %d\n",psid,which_ru); */
1641 		if (rf_reconDebug || rf_pssDebug)
1642 			printf("Warning: no pss descriptor upon unblock on psid %ld RU %d\n", (long) psid, which_ru);
1643 		goto out;
1644 	}
1645 	pssPtr->blockCount--;
1646 	Dprintf3("raid%d: unblocking recon on psid %ld: blockcount is %d\n",
1647 		 raidPtr->raidid, psid, pssPtr->blockCount);
1648 	if (pssPtr->blockCount == 0) {	/* if recon blockage has been released */
1649 
1650 		/* unblock recon before calling CauseReconEvent in case
1651 		 * CauseReconEvent causes us to try to issue a new read before
1652 		 * returning here. */
1653 		pssPtr->flags &= ~RF_PSS_RECON_BLOCKED;
1654 
1655 
1656 		while (pssPtr->blockWaitList) {
1657 			/* spin through the block-wait list and
1658 			   release all the waiters */
1659 			cb = pssPtr->blockWaitList;
1660 			pssPtr->blockWaitList = cb->next;
1661 			cb->next = NULL;
1662 			rf_CauseReconEvent(raidPtr, cb->row, cb->col, NULL, RF_REVENT_BLOCKCLEAR);
1663 			rf_FreeCallbackDesc(cb);
1664 		}
1665 		if (!(pssPtr->flags & RF_PSS_UNDER_RECON)) {
1666 			/* if no recon was requested while recon was blocked */
1667 			rf_PSStatusDelete(raidPtr, raidPtr->reconControl[row]->pssTable, pssPtr);
1668 		}
1669 	}
1670 out:
1671 	RF_UNLOCK_PSS_MUTEX(raidPtr, row, psid);
1672 	return (0);
1673 }
1674