xref: /openbmc/linux/drivers/md/raid5.c (revision 97da55fc)
1 /*
2  * raid5.c : Multiple Devices driver for Linux
3  *	   Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
4  *	   Copyright (C) 1999, 2000 Ingo Molnar
5  *	   Copyright (C) 2002, 2003 H. Peter Anvin
6  *
7  * RAID-4/5/6 management functions.
8  * Thanks to Penguin Computing for making the RAID-6 development possible
9  * by donating a test server!
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2, or (at your option)
14  * any later version.
15  *
16  * You should have received a copy of the GNU General Public License
17  * (for example /usr/src/linux/COPYING); if not, write to the Free
18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 /*
22  * BITMAP UNPLUGGING:
23  *
24  * The sequencing for updating the bitmap reliably is a little
25  * subtle (and I got it wrong the first time) so it deserves some
26  * explanation.
27  *
28  * We group bitmap updates into batches.  Each batch has a number.
29  * We may write out several batches at once, but that isn't very important.
30  * conf->seq_write is the number of the last batch successfully written.
31  * conf->seq_flush is the number of the last batch that was closed to
32  *    new additions.
33  * When we discover that we will need to write to any block in a stripe
34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
35  * the number of the batch it will be in. This is seq_flush+1.
36  * When we are ready to do a write, if that batch hasn't been written yet,
37  *   we plug the array and queue the stripe for later.
38  * When an unplug happens, we increment bm_flush, thus closing the current
39  *   batch.
40  * When we notice that bm_flush > bm_write, we write out all pending updates
41  * to the bitmap, and advance bm_write to where bm_flush was.
42  * This may occasionally write a bit out twice, but is sure never to
43  * miss any bits.
44  */
45 
46 #include <linux/blkdev.h>
47 #include <linux/kthread.h>
48 #include <linux/raid/pq.h>
49 #include <linux/async_tx.h>
50 #include <linux/module.h>
51 #include <linux/async.h>
52 #include <linux/seq_file.h>
53 #include <linux/cpu.h>
54 #include <linux/slab.h>
55 #include <linux/ratelimit.h>
56 #include <trace/events/block.h>
57 
58 #include "md.h"
59 #include "raid5.h"
60 #include "raid0.h"
61 #include "bitmap.h"
62 
63 /*
64  * Stripe cache
65  */
66 
67 #define NR_STRIPES		256
68 #define STRIPE_SIZE		PAGE_SIZE
69 #define STRIPE_SHIFT		(PAGE_SHIFT - 9)
70 #define STRIPE_SECTORS		(STRIPE_SIZE>>9)
71 #define	IO_THRESHOLD		1
72 #define BYPASS_THRESHOLD	1
73 #define NR_HASH			(PAGE_SIZE / sizeof(struct hlist_head))
74 #define HASH_MASK		(NR_HASH - 1)
75 
76 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
77 {
78 	int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
79 	return &conf->stripe_hashtbl[hash];
80 }
81 
82 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
83  * order without overlap.  There may be several bio's per stripe+device, and
84  * a bio could span several devices.
85  * When walking this list for a particular stripe+device, we must never proceed
86  * beyond a bio that extends past this device, as the next bio might no longer
87  * be valid.
88  * This function is used to determine the 'next' bio in the list, given the sector
89  * of the current stripe+device
90  */
91 static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
92 {
93 	int sectors = bio->bi_size >> 9;
94 	if (bio->bi_sector + sectors < sector + STRIPE_SECTORS)
95 		return bio->bi_next;
96 	else
97 		return NULL;
98 }
99 
100 /*
101  * We maintain a biased count of active stripes in the bottom 16 bits of
102  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
103  */
104 static inline int raid5_bi_processed_stripes(struct bio *bio)
105 {
106 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
107 	return (atomic_read(segments) >> 16) & 0xffff;
108 }
109 
110 static inline int raid5_dec_bi_active_stripes(struct bio *bio)
111 {
112 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
113 	return atomic_sub_return(1, segments) & 0xffff;
114 }
115 
116 static inline void raid5_inc_bi_active_stripes(struct bio *bio)
117 {
118 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
119 	atomic_inc(segments);
120 }
121 
122 static inline void raid5_set_bi_processed_stripes(struct bio *bio,
123 	unsigned int cnt)
124 {
125 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
126 	int old, new;
127 
128 	do {
129 		old = atomic_read(segments);
130 		new = (old & 0xffff) | (cnt << 16);
131 	} while (atomic_cmpxchg(segments, old, new) != old);
132 }
133 
134 static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
135 {
136 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
137 	atomic_set(segments, cnt);
138 }
139 
140 /* Find first data disk in a raid6 stripe */
141 static inline int raid6_d0(struct stripe_head *sh)
142 {
143 	if (sh->ddf_layout)
144 		/* ddf always start from first device */
145 		return 0;
146 	/* md starts just after Q block */
147 	if (sh->qd_idx == sh->disks - 1)
148 		return 0;
149 	else
150 		return sh->qd_idx + 1;
151 }
152 static inline int raid6_next_disk(int disk, int raid_disks)
153 {
154 	disk++;
155 	return (disk < raid_disks) ? disk : 0;
156 }
157 
158 /* When walking through the disks in a raid5, starting at raid6_d0,
159  * We need to map each disk to a 'slot', where the data disks are slot
160  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
161  * is raid_disks-1.  This help does that mapping.
162  */
163 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
164 			     int *count, int syndrome_disks)
165 {
166 	int slot = *count;
167 
168 	if (sh->ddf_layout)
169 		(*count)++;
170 	if (idx == sh->pd_idx)
171 		return syndrome_disks;
172 	if (idx == sh->qd_idx)
173 		return syndrome_disks + 1;
174 	if (!sh->ddf_layout)
175 		(*count)++;
176 	return slot;
177 }
178 
179 static void return_io(struct bio *return_bi)
180 {
181 	struct bio *bi = return_bi;
182 	while (bi) {
183 
184 		return_bi = bi->bi_next;
185 		bi->bi_next = NULL;
186 		bi->bi_size = 0;
187 		bio_endio(bi, 0);
188 		bi = return_bi;
189 	}
190 }
191 
192 static void print_raid5_conf (struct r5conf *conf);
193 
194 static int stripe_operations_active(struct stripe_head *sh)
195 {
196 	return sh->check_state || sh->reconstruct_state ||
197 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
198 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
199 }
200 
201 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh)
202 {
203 	BUG_ON(!list_empty(&sh->lru));
204 	BUG_ON(atomic_read(&conf->active_stripes)==0);
205 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
206 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
207 		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
208 			list_add_tail(&sh->lru, &conf->delayed_list);
209 		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
210 			   sh->bm_seq - conf->seq_write > 0)
211 			list_add_tail(&sh->lru, &conf->bitmap_list);
212 		else {
213 			clear_bit(STRIPE_DELAYED, &sh->state);
214 			clear_bit(STRIPE_BIT_DELAY, &sh->state);
215 			list_add_tail(&sh->lru, &conf->handle_list);
216 		}
217 		md_wakeup_thread(conf->mddev->thread);
218 	} else {
219 		BUG_ON(stripe_operations_active(sh));
220 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
221 			if (atomic_dec_return(&conf->preread_active_stripes)
222 			    < IO_THRESHOLD)
223 				md_wakeup_thread(conf->mddev->thread);
224 		atomic_dec(&conf->active_stripes);
225 		if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
226 			list_add_tail(&sh->lru, &conf->inactive_list);
227 			wake_up(&conf->wait_for_stripe);
228 			if (conf->retry_read_aligned)
229 				md_wakeup_thread(conf->mddev->thread);
230 		}
231 	}
232 }
233 
234 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
235 {
236 	if (atomic_dec_and_test(&sh->count))
237 		do_release_stripe(conf, sh);
238 }
239 
240 static void release_stripe(struct stripe_head *sh)
241 {
242 	struct r5conf *conf = sh->raid_conf;
243 	unsigned long flags;
244 
245 	local_irq_save(flags);
246 	if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
247 		do_release_stripe(conf, sh);
248 		spin_unlock(&conf->device_lock);
249 	}
250 	local_irq_restore(flags);
251 }
252 
253 static inline void remove_hash(struct stripe_head *sh)
254 {
255 	pr_debug("remove_hash(), stripe %llu\n",
256 		(unsigned long long)sh->sector);
257 
258 	hlist_del_init(&sh->hash);
259 }
260 
261 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
262 {
263 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
264 
265 	pr_debug("insert_hash(), stripe %llu\n",
266 		(unsigned long long)sh->sector);
267 
268 	hlist_add_head(&sh->hash, hp);
269 }
270 
271 
272 /* find an idle stripe, make sure it is unhashed, and return it. */
273 static struct stripe_head *get_free_stripe(struct r5conf *conf)
274 {
275 	struct stripe_head *sh = NULL;
276 	struct list_head *first;
277 
278 	if (list_empty(&conf->inactive_list))
279 		goto out;
280 	first = conf->inactive_list.next;
281 	sh = list_entry(first, struct stripe_head, lru);
282 	list_del_init(first);
283 	remove_hash(sh);
284 	atomic_inc(&conf->active_stripes);
285 out:
286 	return sh;
287 }
288 
289 static void shrink_buffers(struct stripe_head *sh)
290 {
291 	struct page *p;
292 	int i;
293 	int num = sh->raid_conf->pool_size;
294 
295 	for (i = 0; i < num ; i++) {
296 		p = sh->dev[i].page;
297 		if (!p)
298 			continue;
299 		sh->dev[i].page = NULL;
300 		put_page(p);
301 	}
302 }
303 
304 static int grow_buffers(struct stripe_head *sh)
305 {
306 	int i;
307 	int num = sh->raid_conf->pool_size;
308 
309 	for (i = 0; i < num; i++) {
310 		struct page *page;
311 
312 		if (!(page = alloc_page(GFP_KERNEL))) {
313 			return 1;
314 		}
315 		sh->dev[i].page = page;
316 	}
317 	return 0;
318 }
319 
320 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
321 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
322 			    struct stripe_head *sh);
323 
324 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
325 {
326 	struct r5conf *conf = sh->raid_conf;
327 	int i;
328 
329 	BUG_ON(atomic_read(&sh->count) != 0);
330 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
331 	BUG_ON(stripe_operations_active(sh));
332 
333 	pr_debug("init_stripe called, stripe %llu\n",
334 		(unsigned long long)sh->sector);
335 
336 	remove_hash(sh);
337 
338 	sh->generation = conf->generation - previous;
339 	sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
340 	sh->sector = sector;
341 	stripe_set_idx(sector, conf, previous, sh);
342 	sh->state = 0;
343 
344 
345 	for (i = sh->disks; i--; ) {
346 		struct r5dev *dev = &sh->dev[i];
347 
348 		if (dev->toread || dev->read || dev->towrite || dev->written ||
349 		    test_bit(R5_LOCKED, &dev->flags)) {
350 			printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
351 			       (unsigned long long)sh->sector, i, dev->toread,
352 			       dev->read, dev->towrite, dev->written,
353 			       test_bit(R5_LOCKED, &dev->flags));
354 			WARN_ON(1);
355 		}
356 		dev->flags = 0;
357 		raid5_build_block(sh, i, previous);
358 	}
359 	insert_hash(conf, sh);
360 }
361 
362 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
363 					 short generation)
364 {
365 	struct stripe_head *sh;
366 
367 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
368 	hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
369 		if (sh->sector == sector && sh->generation == generation)
370 			return sh;
371 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
372 	return NULL;
373 }
374 
375 /*
376  * Need to check if array has failed when deciding whether to:
377  *  - start an array
378  *  - remove non-faulty devices
379  *  - add a spare
380  *  - allow a reshape
381  * This determination is simple when no reshape is happening.
382  * However if there is a reshape, we need to carefully check
383  * both the before and after sections.
384  * This is because some failed devices may only affect one
385  * of the two sections, and some non-in_sync devices may
386  * be insync in the section most affected by failed devices.
387  */
388 static int calc_degraded(struct r5conf *conf)
389 {
390 	int degraded, degraded2;
391 	int i;
392 
393 	rcu_read_lock();
394 	degraded = 0;
395 	for (i = 0; i < conf->previous_raid_disks; i++) {
396 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
397 		if (rdev && test_bit(Faulty, &rdev->flags))
398 			rdev = rcu_dereference(conf->disks[i].replacement);
399 		if (!rdev || test_bit(Faulty, &rdev->flags))
400 			degraded++;
401 		else if (test_bit(In_sync, &rdev->flags))
402 			;
403 		else
404 			/* not in-sync or faulty.
405 			 * If the reshape increases the number of devices,
406 			 * this is being recovered by the reshape, so
407 			 * this 'previous' section is not in_sync.
408 			 * If the number of devices is being reduced however,
409 			 * the device can only be part of the array if
410 			 * we are reverting a reshape, so this section will
411 			 * be in-sync.
412 			 */
413 			if (conf->raid_disks >= conf->previous_raid_disks)
414 				degraded++;
415 	}
416 	rcu_read_unlock();
417 	if (conf->raid_disks == conf->previous_raid_disks)
418 		return degraded;
419 	rcu_read_lock();
420 	degraded2 = 0;
421 	for (i = 0; i < conf->raid_disks; i++) {
422 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
423 		if (rdev && test_bit(Faulty, &rdev->flags))
424 			rdev = rcu_dereference(conf->disks[i].replacement);
425 		if (!rdev || test_bit(Faulty, &rdev->flags))
426 			degraded2++;
427 		else if (test_bit(In_sync, &rdev->flags))
428 			;
429 		else
430 			/* not in-sync or faulty.
431 			 * If reshape increases the number of devices, this
432 			 * section has already been recovered, else it
433 			 * almost certainly hasn't.
434 			 */
435 			if (conf->raid_disks <= conf->previous_raid_disks)
436 				degraded2++;
437 	}
438 	rcu_read_unlock();
439 	if (degraded2 > degraded)
440 		return degraded2;
441 	return degraded;
442 }
443 
444 static int has_failed(struct r5conf *conf)
445 {
446 	int degraded;
447 
448 	if (conf->mddev->reshape_position == MaxSector)
449 		return conf->mddev->degraded > conf->max_degraded;
450 
451 	degraded = calc_degraded(conf);
452 	if (degraded > conf->max_degraded)
453 		return 1;
454 	return 0;
455 }
456 
457 static struct stripe_head *
458 get_active_stripe(struct r5conf *conf, sector_t sector,
459 		  int previous, int noblock, int noquiesce)
460 {
461 	struct stripe_head *sh;
462 
463 	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
464 
465 	spin_lock_irq(&conf->device_lock);
466 
467 	do {
468 		wait_event_lock_irq(conf->wait_for_stripe,
469 				    conf->quiesce == 0 || noquiesce,
470 				    conf->device_lock);
471 		sh = __find_stripe(conf, sector, conf->generation - previous);
472 		if (!sh) {
473 			if (!conf->inactive_blocked)
474 				sh = get_free_stripe(conf);
475 			if (noblock && sh == NULL)
476 				break;
477 			if (!sh) {
478 				conf->inactive_blocked = 1;
479 				wait_event_lock_irq(conf->wait_for_stripe,
480 						    !list_empty(&conf->inactive_list) &&
481 						    (atomic_read(&conf->active_stripes)
482 						     < (conf->max_nr_stripes *3/4)
483 						     || !conf->inactive_blocked),
484 						    conf->device_lock);
485 				conf->inactive_blocked = 0;
486 			} else
487 				init_stripe(sh, sector, previous);
488 		} else {
489 			if (atomic_read(&sh->count)) {
490 				BUG_ON(!list_empty(&sh->lru)
491 				    && !test_bit(STRIPE_EXPANDING, &sh->state)
492 				    && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
493 			} else {
494 				if (!test_bit(STRIPE_HANDLE, &sh->state))
495 					atomic_inc(&conf->active_stripes);
496 				if (list_empty(&sh->lru) &&
497 				    !test_bit(STRIPE_EXPANDING, &sh->state))
498 					BUG();
499 				list_del_init(&sh->lru);
500 			}
501 		}
502 	} while (sh == NULL);
503 
504 	if (sh)
505 		atomic_inc(&sh->count);
506 
507 	spin_unlock_irq(&conf->device_lock);
508 	return sh;
509 }
510 
511 /* Determine if 'data_offset' or 'new_data_offset' should be used
512  * in this stripe_head.
513  */
514 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
515 {
516 	sector_t progress = conf->reshape_progress;
517 	/* Need a memory barrier to make sure we see the value
518 	 * of conf->generation, or ->data_offset that was set before
519 	 * reshape_progress was updated.
520 	 */
521 	smp_rmb();
522 	if (progress == MaxSector)
523 		return 0;
524 	if (sh->generation == conf->generation - 1)
525 		return 0;
526 	/* We are in a reshape, and this is a new-generation stripe,
527 	 * so use new_data_offset.
528 	 */
529 	return 1;
530 }
531 
532 static void
533 raid5_end_read_request(struct bio *bi, int error);
534 static void
535 raid5_end_write_request(struct bio *bi, int error);
536 
537 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
538 {
539 	struct r5conf *conf = sh->raid_conf;
540 	int i, disks = sh->disks;
541 
542 	might_sleep();
543 
544 	for (i = disks; i--; ) {
545 		int rw;
546 		int replace_only = 0;
547 		struct bio *bi, *rbi;
548 		struct md_rdev *rdev, *rrdev = NULL;
549 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
550 			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
551 				rw = WRITE_FUA;
552 			else
553 				rw = WRITE;
554 			if (test_bit(R5_Discard, &sh->dev[i].flags))
555 				rw |= REQ_DISCARD;
556 		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
557 			rw = READ;
558 		else if (test_and_clear_bit(R5_WantReplace,
559 					    &sh->dev[i].flags)) {
560 			rw = WRITE;
561 			replace_only = 1;
562 		} else
563 			continue;
564 		if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
565 			rw |= REQ_SYNC;
566 
567 		bi = &sh->dev[i].req;
568 		rbi = &sh->dev[i].rreq; /* For writing to replacement */
569 
570 		bi->bi_rw = rw;
571 		rbi->bi_rw = rw;
572 		if (rw & WRITE) {
573 			bi->bi_end_io = raid5_end_write_request;
574 			rbi->bi_end_io = raid5_end_write_request;
575 		} else
576 			bi->bi_end_io = raid5_end_read_request;
577 
578 		rcu_read_lock();
579 		rrdev = rcu_dereference(conf->disks[i].replacement);
580 		smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
581 		rdev = rcu_dereference(conf->disks[i].rdev);
582 		if (!rdev) {
583 			rdev = rrdev;
584 			rrdev = NULL;
585 		}
586 		if (rw & WRITE) {
587 			if (replace_only)
588 				rdev = NULL;
589 			if (rdev == rrdev)
590 				/* We raced and saw duplicates */
591 				rrdev = NULL;
592 		} else {
593 			if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
594 				rdev = rrdev;
595 			rrdev = NULL;
596 		}
597 
598 		if (rdev && test_bit(Faulty, &rdev->flags))
599 			rdev = NULL;
600 		if (rdev)
601 			atomic_inc(&rdev->nr_pending);
602 		if (rrdev && test_bit(Faulty, &rrdev->flags))
603 			rrdev = NULL;
604 		if (rrdev)
605 			atomic_inc(&rrdev->nr_pending);
606 		rcu_read_unlock();
607 
608 		/* We have already checked bad blocks for reads.  Now
609 		 * need to check for writes.  We never accept write errors
610 		 * on the replacement, so we don't to check rrdev.
611 		 */
612 		while ((rw & WRITE) && rdev &&
613 		       test_bit(WriteErrorSeen, &rdev->flags)) {
614 			sector_t first_bad;
615 			int bad_sectors;
616 			int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
617 					      &first_bad, &bad_sectors);
618 			if (!bad)
619 				break;
620 
621 			if (bad < 0) {
622 				set_bit(BlockedBadBlocks, &rdev->flags);
623 				if (!conf->mddev->external &&
624 				    conf->mddev->flags) {
625 					/* It is very unlikely, but we might
626 					 * still need to write out the
627 					 * bad block log - better give it
628 					 * a chance*/
629 					md_check_recovery(conf->mddev);
630 				}
631 				/*
632 				 * Because md_wait_for_blocked_rdev
633 				 * will dec nr_pending, we must
634 				 * increment it first.
635 				 */
636 				atomic_inc(&rdev->nr_pending);
637 				md_wait_for_blocked_rdev(rdev, conf->mddev);
638 			} else {
639 				/* Acknowledged bad block - skip the write */
640 				rdev_dec_pending(rdev, conf->mddev);
641 				rdev = NULL;
642 			}
643 		}
644 
645 		if (rdev) {
646 			if (s->syncing || s->expanding || s->expanded
647 			    || s->replacing)
648 				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
649 
650 			set_bit(STRIPE_IO_STARTED, &sh->state);
651 
652 			bi->bi_bdev = rdev->bdev;
653 			pr_debug("%s: for %llu schedule op %ld on disc %d\n",
654 				__func__, (unsigned long long)sh->sector,
655 				bi->bi_rw, i);
656 			atomic_inc(&sh->count);
657 			if (use_new_offset(conf, sh))
658 				bi->bi_sector = (sh->sector
659 						 + rdev->new_data_offset);
660 			else
661 				bi->bi_sector = (sh->sector
662 						 + rdev->data_offset);
663 			if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
664 				bi->bi_rw |= REQ_FLUSH;
665 
666 			bi->bi_flags = 1 << BIO_UPTODATE;
667 			bi->bi_idx = 0;
668 			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
669 			bi->bi_io_vec[0].bv_offset = 0;
670 			bi->bi_size = STRIPE_SIZE;
671 			bi->bi_next = NULL;
672 			if (rrdev)
673 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
674 			trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
675 					      bi, disk_devt(conf->mddev->gendisk),
676 					      sh->dev[i].sector);
677 			generic_make_request(bi);
678 		}
679 		if (rrdev) {
680 			if (s->syncing || s->expanding || s->expanded
681 			    || s->replacing)
682 				md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
683 
684 			set_bit(STRIPE_IO_STARTED, &sh->state);
685 
686 			rbi->bi_bdev = rrdev->bdev;
687 			pr_debug("%s: for %llu schedule op %ld on "
688 				 "replacement disc %d\n",
689 				__func__, (unsigned long long)sh->sector,
690 				rbi->bi_rw, i);
691 			atomic_inc(&sh->count);
692 			if (use_new_offset(conf, sh))
693 				rbi->bi_sector = (sh->sector
694 						  + rrdev->new_data_offset);
695 			else
696 				rbi->bi_sector = (sh->sector
697 						  + rrdev->data_offset);
698 			rbi->bi_flags = 1 << BIO_UPTODATE;
699 			rbi->bi_idx = 0;
700 			rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
701 			rbi->bi_io_vec[0].bv_offset = 0;
702 			rbi->bi_size = STRIPE_SIZE;
703 			rbi->bi_next = NULL;
704 			trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
705 					      rbi, disk_devt(conf->mddev->gendisk),
706 					      sh->dev[i].sector);
707 			generic_make_request(rbi);
708 		}
709 		if (!rdev && !rrdev) {
710 			if (rw & WRITE)
711 				set_bit(STRIPE_DEGRADED, &sh->state);
712 			pr_debug("skip op %ld on disc %d for sector %llu\n",
713 				bi->bi_rw, i, (unsigned long long)sh->sector);
714 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
715 			set_bit(STRIPE_HANDLE, &sh->state);
716 		}
717 	}
718 }
719 
720 static struct dma_async_tx_descriptor *
721 async_copy_data(int frombio, struct bio *bio, struct page *page,
722 	sector_t sector, struct dma_async_tx_descriptor *tx)
723 {
724 	struct bio_vec *bvl;
725 	struct page *bio_page;
726 	int i;
727 	int page_offset;
728 	struct async_submit_ctl submit;
729 	enum async_tx_flags flags = 0;
730 
731 	if (bio->bi_sector >= sector)
732 		page_offset = (signed)(bio->bi_sector - sector) * 512;
733 	else
734 		page_offset = (signed)(sector - bio->bi_sector) * -512;
735 
736 	if (frombio)
737 		flags |= ASYNC_TX_FENCE;
738 	init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
739 
740 	bio_for_each_segment(bvl, bio, i) {
741 		int len = bvl->bv_len;
742 		int clen;
743 		int b_offset = 0;
744 
745 		if (page_offset < 0) {
746 			b_offset = -page_offset;
747 			page_offset += b_offset;
748 			len -= b_offset;
749 		}
750 
751 		if (len > 0 && page_offset + len > STRIPE_SIZE)
752 			clen = STRIPE_SIZE - page_offset;
753 		else
754 			clen = len;
755 
756 		if (clen > 0) {
757 			b_offset += bvl->bv_offset;
758 			bio_page = bvl->bv_page;
759 			if (frombio)
760 				tx = async_memcpy(page, bio_page, page_offset,
761 						  b_offset, clen, &submit);
762 			else
763 				tx = async_memcpy(bio_page, page, b_offset,
764 						  page_offset, clen, &submit);
765 		}
766 		/* chain the operations */
767 		submit.depend_tx = tx;
768 
769 		if (clen < len) /* hit end of page */
770 			break;
771 		page_offset +=  len;
772 	}
773 
774 	return tx;
775 }
776 
777 static void ops_complete_biofill(void *stripe_head_ref)
778 {
779 	struct stripe_head *sh = stripe_head_ref;
780 	struct bio *return_bi = NULL;
781 	int i;
782 
783 	pr_debug("%s: stripe %llu\n", __func__,
784 		(unsigned long long)sh->sector);
785 
786 	/* clear completed biofills */
787 	for (i = sh->disks; i--; ) {
788 		struct r5dev *dev = &sh->dev[i];
789 
790 		/* acknowledge completion of a biofill operation */
791 		/* and check if we need to reply to a read request,
792 		 * new R5_Wantfill requests are held off until
793 		 * !STRIPE_BIOFILL_RUN
794 		 */
795 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
796 			struct bio *rbi, *rbi2;
797 
798 			BUG_ON(!dev->read);
799 			rbi = dev->read;
800 			dev->read = NULL;
801 			while (rbi && rbi->bi_sector <
802 				dev->sector + STRIPE_SECTORS) {
803 				rbi2 = r5_next_bio(rbi, dev->sector);
804 				if (!raid5_dec_bi_active_stripes(rbi)) {
805 					rbi->bi_next = return_bi;
806 					return_bi = rbi;
807 				}
808 				rbi = rbi2;
809 			}
810 		}
811 	}
812 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
813 
814 	return_io(return_bi);
815 
816 	set_bit(STRIPE_HANDLE, &sh->state);
817 	release_stripe(sh);
818 }
819 
820 static void ops_run_biofill(struct stripe_head *sh)
821 {
822 	struct dma_async_tx_descriptor *tx = NULL;
823 	struct async_submit_ctl submit;
824 	int i;
825 
826 	pr_debug("%s: stripe %llu\n", __func__,
827 		(unsigned long long)sh->sector);
828 
829 	for (i = sh->disks; i--; ) {
830 		struct r5dev *dev = &sh->dev[i];
831 		if (test_bit(R5_Wantfill, &dev->flags)) {
832 			struct bio *rbi;
833 			spin_lock_irq(&sh->stripe_lock);
834 			dev->read = rbi = dev->toread;
835 			dev->toread = NULL;
836 			spin_unlock_irq(&sh->stripe_lock);
837 			while (rbi && rbi->bi_sector <
838 				dev->sector + STRIPE_SECTORS) {
839 				tx = async_copy_data(0, rbi, dev->page,
840 					dev->sector, tx);
841 				rbi = r5_next_bio(rbi, dev->sector);
842 			}
843 		}
844 	}
845 
846 	atomic_inc(&sh->count);
847 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
848 	async_trigger_callback(&submit);
849 }
850 
851 static void mark_target_uptodate(struct stripe_head *sh, int target)
852 {
853 	struct r5dev *tgt;
854 
855 	if (target < 0)
856 		return;
857 
858 	tgt = &sh->dev[target];
859 	set_bit(R5_UPTODATE, &tgt->flags);
860 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
861 	clear_bit(R5_Wantcompute, &tgt->flags);
862 }
863 
864 static void ops_complete_compute(void *stripe_head_ref)
865 {
866 	struct stripe_head *sh = stripe_head_ref;
867 
868 	pr_debug("%s: stripe %llu\n", __func__,
869 		(unsigned long long)sh->sector);
870 
871 	/* mark the computed target(s) as uptodate */
872 	mark_target_uptodate(sh, sh->ops.target);
873 	mark_target_uptodate(sh, sh->ops.target2);
874 
875 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
876 	if (sh->check_state == check_state_compute_run)
877 		sh->check_state = check_state_compute_result;
878 	set_bit(STRIPE_HANDLE, &sh->state);
879 	release_stripe(sh);
880 }
881 
882 /* return a pointer to the address conversion region of the scribble buffer */
883 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
884 				 struct raid5_percpu *percpu)
885 {
886 	return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
887 }
888 
889 static struct dma_async_tx_descriptor *
890 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
891 {
892 	int disks = sh->disks;
893 	struct page **xor_srcs = percpu->scribble;
894 	int target = sh->ops.target;
895 	struct r5dev *tgt = &sh->dev[target];
896 	struct page *xor_dest = tgt->page;
897 	int count = 0;
898 	struct dma_async_tx_descriptor *tx;
899 	struct async_submit_ctl submit;
900 	int i;
901 
902 	pr_debug("%s: stripe %llu block: %d\n",
903 		__func__, (unsigned long long)sh->sector, target);
904 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
905 
906 	for (i = disks; i--; )
907 		if (i != target)
908 			xor_srcs[count++] = sh->dev[i].page;
909 
910 	atomic_inc(&sh->count);
911 
912 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
913 			  ops_complete_compute, sh, to_addr_conv(sh, percpu));
914 	if (unlikely(count == 1))
915 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
916 	else
917 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
918 
919 	return tx;
920 }
921 
922 /* set_syndrome_sources - populate source buffers for gen_syndrome
923  * @srcs - (struct page *) array of size sh->disks
924  * @sh - stripe_head to parse
925  *
926  * Populates srcs in proper layout order for the stripe and returns the
927  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
928  * destination buffer is recorded in srcs[count] and the Q destination
929  * is recorded in srcs[count+1]].
930  */
931 static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
932 {
933 	int disks = sh->disks;
934 	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
935 	int d0_idx = raid6_d0(sh);
936 	int count;
937 	int i;
938 
939 	for (i = 0; i < disks; i++)
940 		srcs[i] = NULL;
941 
942 	count = 0;
943 	i = d0_idx;
944 	do {
945 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
946 
947 		srcs[slot] = sh->dev[i].page;
948 		i = raid6_next_disk(i, disks);
949 	} while (i != d0_idx);
950 
951 	return syndrome_disks;
952 }
953 
954 static struct dma_async_tx_descriptor *
955 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
956 {
957 	int disks = sh->disks;
958 	struct page **blocks = percpu->scribble;
959 	int target;
960 	int qd_idx = sh->qd_idx;
961 	struct dma_async_tx_descriptor *tx;
962 	struct async_submit_ctl submit;
963 	struct r5dev *tgt;
964 	struct page *dest;
965 	int i;
966 	int count;
967 
968 	if (sh->ops.target < 0)
969 		target = sh->ops.target2;
970 	else if (sh->ops.target2 < 0)
971 		target = sh->ops.target;
972 	else
973 		/* we should only have one valid target */
974 		BUG();
975 	BUG_ON(target < 0);
976 	pr_debug("%s: stripe %llu block: %d\n",
977 		__func__, (unsigned long long)sh->sector, target);
978 
979 	tgt = &sh->dev[target];
980 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
981 	dest = tgt->page;
982 
983 	atomic_inc(&sh->count);
984 
985 	if (target == qd_idx) {
986 		count = set_syndrome_sources(blocks, sh);
987 		blocks[count] = NULL; /* regenerating p is not necessary */
988 		BUG_ON(blocks[count+1] != dest); /* q should already be set */
989 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
990 				  ops_complete_compute, sh,
991 				  to_addr_conv(sh, percpu));
992 		tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
993 	} else {
994 		/* Compute any data- or p-drive using XOR */
995 		count = 0;
996 		for (i = disks; i-- ; ) {
997 			if (i == target || i == qd_idx)
998 				continue;
999 			blocks[count++] = sh->dev[i].page;
1000 		}
1001 
1002 		init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1003 				  NULL, ops_complete_compute, sh,
1004 				  to_addr_conv(sh, percpu));
1005 		tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1006 	}
1007 
1008 	return tx;
1009 }
1010 
1011 static struct dma_async_tx_descriptor *
1012 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1013 {
1014 	int i, count, disks = sh->disks;
1015 	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1016 	int d0_idx = raid6_d0(sh);
1017 	int faila = -1, failb = -1;
1018 	int target = sh->ops.target;
1019 	int target2 = sh->ops.target2;
1020 	struct r5dev *tgt = &sh->dev[target];
1021 	struct r5dev *tgt2 = &sh->dev[target2];
1022 	struct dma_async_tx_descriptor *tx;
1023 	struct page **blocks = percpu->scribble;
1024 	struct async_submit_ctl submit;
1025 
1026 	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1027 		 __func__, (unsigned long long)sh->sector, target, target2);
1028 	BUG_ON(target < 0 || target2 < 0);
1029 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1030 	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1031 
1032 	/* we need to open-code set_syndrome_sources to handle the
1033 	 * slot number conversion for 'faila' and 'failb'
1034 	 */
1035 	for (i = 0; i < disks ; i++)
1036 		blocks[i] = NULL;
1037 	count = 0;
1038 	i = d0_idx;
1039 	do {
1040 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1041 
1042 		blocks[slot] = sh->dev[i].page;
1043 
1044 		if (i == target)
1045 			faila = slot;
1046 		if (i == target2)
1047 			failb = slot;
1048 		i = raid6_next_disk(i, disks);
1049 	} while (i != d0_idx);
1050 
1051 	BUG_ON(faila == failb);
1052 	if (failb < faila)
1053 		swap(faila, failb);
1054 	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1055 		 __func__, (unsigned long long)sh->sector, faila, failb);
1056 
1057 	atomic_inc(&sh->count);
1058 
1059 	if (failb == syndrome_disks+1) {
1060 		/* Q disk is one of the missing disks */
1061 		if (faila == syndrome_disks) {
1062 			/* Missing P+Q, just recompute */
1063 			init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1064 					  ops_complete_compute, sh,
1065 					  to_addr_conv(sh, percpu));
1066 			return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1067 						  STRIPE_SIZE, &submit);
1068 		} else {
1069 			struct page *dest;
1070 			int data_target;
1071 			int qd_idx = sh->qd_idx;
1072 
1073 			/* Missing D+Q: recompute D from P, then recompute Q */
1074 			if (target == qd_idx)
1075 				data_target = target2;
1076 			else
1077 				data_target = target;
1078 
1079 			count = 0;
1080 			for (i = disks; i-- ; ) {
1081 				if (i == data_target || i == qd_idx)
1082 					continue;
1083 				blocks[count++] = sh->dev[i].page;
1084 			}
1085 			dest = sh->dev[data_target].page;
1086 			init_async_submit(&submit,
1087 					  ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1088 					  NULL, NULL, NULL,
1089 					  to_addr_conv(sh, percpu));
1090 			tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1091 				       &submit);
1092 
1093 			count = set_syndrome_sources(blocks, sh);
1094 			init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1095 					  ops_complete_compute, sh,
1096 					  to_addr_conv(sh, percpu));
1097 			return async_gen_syndrome(blocks, 0, count+2,
1098 						  STRIPE_SIZE, &submit);
1099 		}
1100 	} else {
1101 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1102 				  ops_complete_compute, sh,
1103 				  to_addr_conv(sh, percpu));
1104 		if (failb == syndrome_disks) {
1105 			/* We're missing D+P. */
1106 			return async_raid6_datap_recov(syndrome_disks+2,
1107 						       STRIPE_SIZE, faila,
1108 						       blocks, &submit);
1109 		} else {
1110 			/* We're missing D+D. */
1111 			return async_raid6_2data_recov(syndrome_disks+2,
1112 						       STRIPE_SIZE, faila, failb,
1113 						       blocks, &submit);
1114 		}
1115 	}
1116 }
1117 
1118 
1119 static void ops_complete_prexor(void *stripe_head_ref)
1120 {
1121 	struct stripe_head *sh = stripe_head_ref;
1122 
1123 	pr_debug("%s: stripe %llu\n", __func__,
1124 		(unsigned long long)sh->sector);
1125 }
1126 
1127 static struct dma_async_tx_descriptor *
1128 ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1129 	       struct dma_async_tx_descriptor *tx)
1130 {
1131 	int disks = sh->disks;
1132 	struct page **xor_srcs = percpu->scribble;
1133 	int count = 0, pd_idx = sh->pd_idx, i;
1134 	struct async_submit_ctl submit;
1135 
1136 	/* existing parity data subtracted */
1137 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1138 
1139 	pr_debug("%s: stripe %llu\n", __func__,
1140 		(unsigned long long)sh->sector);
1141 
1142 	for (i = disks; i--; ) {
1143 		struct r5dev *dev = &sh->dev[i];
1144 		/* Only process blocks that are known to be uptodate */
1145 		if (test_bit(R5_Wantdrain, &dev->flags))
1146 			xor_srcs[count++] = dev->page;
1147 	}
1148 
1149 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1150 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1151 	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1152 
1153 	return tx;
1154 }
1155 
1156 static struct dma_async_tx_descriptor *
1157 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1158 {
1159 	int disks = sh->disks;
1160 	int i;
1161 
1162 	pr_debug("%s: stripe %llu\n", __func__,
1163 		(unsigned long long)sh->sector);
1164 
1165 	for (i = disks; i--; ) {
1166 		struct r5dev *dev = &sh->dev[i];
1167 		struct bio *chosen;
1168 
1169 		if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1170 			struct bio *wbi;
1171 
1172 			spin_lock_irq(&sh->stripe_lock);
1173 			chosen = dev->towrite;
1174 			dev->towrite = NULL;
1175 			BUG_ON(dev->written);
1176 			wbi = dev->written = chosen;
1177 			spin_unlock_irq(&sh->stripe_lock);
1178 
1179 			while (wbi && wbi->bi_sector <
1180 				dev->sector + STRIPE_SECTORS) {
1181 				if (wbi->bi_rw & REQ_FUA)
1182 					set_bit(R5_WantFUA, &dev->flags);
1183 				if (wbi->bi_rw & REQ_SYNC)
1184 					set_bit(R5_SyncIO, &dev->flags);
1185 				if (wbi->bi_rw & REQ_DISCARD)
1186 					set_bit(R5_Discard, &dev->flags);
1187 				else
1188 					tx = async_copy_data(1, wbi, dev->page,
1189 						dev->sector, tx);
1190 				wbi = r5_next_bio(wbi, dev->sector);
1191 			}
1192 		}
1193 	}
1194 
1195 	return tx;
1196 }
1197 
1198 static void ops_complete_reconstruct(void *stripe_head_ref)
1199 {
1200 	struct stripe_head *sh = stripe_head_ref;
1201 	int disks = sh->disks;
1202 	int pd_idx = sh->pd_idx;
1203 	int qd_idx = sh->qd_idx;
1204 	int i;
1205 	bool fua = false, sync = false, discard = false;
1206 
1207 	pr_debug("%s: stripe %llu\n", __func__,
1208 		(unsigned long long)sh->sector);
1209 
1210 	for (i = disks; i--; ) {
1211 		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1212 		sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1213 		discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1214 	}
1215 
1216 	for (i = disks; i--; ) {
1217 		struct r5dev *dev = &sh->dev[i];
1218 
1219 		if (dev->written || i == pd_idx || i == qd_idx) {
1220 			if (!discard)
1221 				set_bit(R5_UPTODATE, &dev->flags);
1222 			if (fua)
1223 				set_bit(R5_WantFUA, &dev->flags);
1224 			if (sync)
1225 				set_bit(R5_SyncIO, &dev->flags);
1226 		}
1227 	}
1228 
1229 	if (sh->reconstruct_state == reconstruct_state_drain_run)
1230 		sh->reconstruct_state = reconstruct_state_drain_result;
1231 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1232 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1233 	else {
1234 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1235 		sh->reconstruct_state = reconstruct_state_result;
1236 	}
1237 
1238 	set_bit(STRIPE_HANDLE, &sh->state);
1239 	release_stripe(sh);
1240 }
1241 
1242 static void
1243 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1244 		     struct dma_async_tx_descriptor *tx)
1245 {
1246 	int disks = sh->disks;
1247 	struct page **xor_srcs = percpu->scribble;
1248 	struct async_submit_ctl submit;
1249 	int count = 0, pd_idx = sh->pd_idx, i;
1250 	struct page *xor_dest;
1251 	int prexor = 0;
1252 	unsigned long flags;
1253 
1254 	pr_debug("%s: stripe %llu\n", __func__,
1255 		(unsigned long long)sh->sector);
1256 
1257 	for (i = 0; i < sh->disks; i++) {
1258 		if (pd_idx == i)
1259 			continue;
1260 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1261 			break;
1262 	}
1263 	if (i >= sh->disks) {
1264 		atomic_inc(&sh->count);
1265 		set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1266 		ops_complete_reconstruct(sh);
1267 		return;
1268 	}
1269 	/* check if prexor is active which means only process blocks
1270 	 * that are part of a read-modify-write (written)
1271 	 */
1272 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1273 		prexor = 1;
1274 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1275 		for (i = disks; i--; ) {
1276 			struct r5dev *dev = &sh->dev[i];
1277 			if (dev->written)
1278 				xor_srcs[count++] = dev->page;
1279 		}
1280 	} else {
1281 		xor_dest = sh->dev[pd_idx].page;
1282 		for (i = disks; i--; ) {
1283 			struct r5dev *dev = &sh->dev[i];
1284 			if (i != pd_idx)
1285 				xor_srcs[count++] = dev->page;
1286 		}
1287 	}
1288 
1289 	/* 1/ if we prexor'd then the dest is reused as a source
1290 	 * 2/ if we did not prexor then we are redoing the parity
1291 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1292 	 * for the synchronous xor case
1293 	 */
1294 	flags = ASYNC_TX_ACK |
1295 		(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1296 
1297 	atomic_inc(&sh->count);
1298 
1299 	init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1300 			  to_addr_conv(sh, percpu));
1301 	if (unlikely(count == 1))
1302 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1303 	else
1304 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1305 }
1306 
1307 static void
1308 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1309 		     struct dma_async_tx_descriptor *tx)
1310 {
1311 	struct async_submit_ctl submit;
1312 	struct page **blocks = percpu->scribble;
1313 	int count, i;
1314 
1315 	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1316 
1317 	for (i = 0; i < sh->disks; i++) {
1318 		if (sh->pd_idx == i || sh->qd_idx == i)
1319 			continue;
1320 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1321 			break;
1322 	}
1323 	if (i >= sh->disks) {
1324 		atomic_inc(&sh->count);
1325 		set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1326 		set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1327 		ops_complete_reconstruct(sh);
1328 		return;
1329 	}
1330 
1331 	count = set_syndrome_sources(blocks, sh);
1332 
1333 	atomic_inc(&sh->count);
1334 
1335 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1336 			  sh, to_addr_conv(sh, percpu));
1337 	async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1338 }
1339 
1340 static void ops_complete_check(void *stripe_head_ref)
1341 {
1342 	struct stripe_head *sh = stripe_head_ref;
1343 
1344 	pr_debug("%s: stripe %llu\n", __func__,
1345 		(unsigned long long)sh->sector);
1346 
1347 	sh->check_state = check_state_check_result;
1348 	set_bit(STRIPE_HANDLE, &sh->state);
1349 	release_stripe(sh);
1350 }
1351 
1352 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1353 {
1354 	int disks = sh->disks;
1355 	int pd_idx = sh->pd_idx;
1356 	int qd_idx = sh->qd_idx;
1357 	struct page *xor_dest;
1358 	struct page **xor_srcs = percpu->scribble;
1359 	struct dma_async_tx_descriptor *tx;
1360 	struct async_submit_ctl submit;
1361 	int count;
1362 	int i;
1363 
1364 	pr_debug("%s: stripe %llu\n", __func__,
1365 		(unsigned long long)sh->sector);
1366 
1367 	count = 0;
1368 	xor_dest = sh->dev[pd_idx].page;
1369 	xor_srcs[count++] = xor_dest;
1370 	for (i = disks; i--; ) {
1371 		if (i == pd_idx || i == qd_idx)
1372 			continue;
1373 		xor_srcs[count++] = sh->dev[i].page;
1374 	}
1375 
1376 	init_async_submit(&submit, 0, NULL, NULL, NULL,
1377 			  to_addr_conv(sh, percpu));
1378 	tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1379 			   &sh->ops.zero_sum_result, &submit);
1380 
1381 	atomic_inc(&sh->count);
1382 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1383 	tx = async_trigger_callback(&submit);
1384 }
1385 
1386 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1387 {
1388 	struct page **srcs = percpu->scribble;
1389 	struct async_submit_ctl submit;
1390 	int count;
1391 
1392 	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1393 		(unsigned long long)sh->sector, checkp);
1394 
1395 	count = set_syndrome_sources(srcs, sh);
1396 	if (!checkp)
1397 		srcs[count] = NULL;
1398 
1399 	atomic_inc(&sh->count);
1400 	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1401 			  sh, to_addr_conv(sh, percpu));
1402 	async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1403 			   &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1404 }
1405 
1406 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1407 {
1408 	int overlap_clear = 0, i, disks = sh->disks;
1409 	struct dma_async_tx_descriptor *tx = NULL;
1410 	struct r5conf *conf = sh->raid_conf;
1411 	int level = conf->level;
1412 	struct raid5_percpu *percpu;
1413 	unsigned long cpu;
1414 
1415 	cpu = get_cpu();
1416 	percpu = per_cpu_ptr(conf->percpu, cpu);
1417 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1418 		ops_run_biofill(sh);
1419 		overlap_clear++;
1420 	}
1421 
1422 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1423 		if (level < 6)
1424 			tx = ops_run_compute5(sh, percpu);
1425 		else {
1426 			if (sh->ops.target2 < 0 || sh->ops.target < 0)
1427 				tx = ops_run_compute6_1(sh, percpu);
1428 			else
1429 				tx = ops_run_compute6_2(sh, percpu);
1430 		}
1431 		/* terminate the chain if reconstruct is not set to be run */
1432 		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1433 			async_tx_ack(tx);
1434 	}
1435 
1436 	if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1437 		tx = ops_run_prexor(sh, percpu, tx);
1438 
1439 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1440 		tx = ops_run_biodrain(sh, tx);
1441 		overlap_clear++;
1442 	}
1443 
1444 	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1445 		if (level < 6)
1446 			ops_run_reconstruct5(sh, percpu, tx);
1447 		else
1448 			ops_run_reconstruct6(sh, percpu, tx);
1449 	}
1450 
1451 	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1452 		if (sh->check_state == check_state_run)
1453 			ops_run_check_p(sh, percpu);
1454 		else if (sh->check_state == check_state_run_q)
1455 			ops_run_check_pq(sh, percpu, 0);
1456 		else if (sh->check_state == check_state_run_pq)
1457 			ops_run_check_pq(sh, percpu, 1);
1458 		else
1459 			BUG();
1460 	}
1461 
1462 	if (overlap_clear)
1463 		for (i = disks; i--; ) {
1464 			struct r5dev *dev = &sh->dev[i];
1465 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
1466 				wake_up(&sh->raid_conf->wait_for_overlap);
1467 		}
1468 	put_cpu();
1469 }
1470 
1471 static int grow_one_stripe(struct r5conf *conf)
1472 {
1473 	struct stripe_head *sh;
1474 	sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1475 	if (!sh)
1476 		return 0;
1477 
1478 	sh->raid_conf = conf;
1479 
1480 	spin_lock_init(&sh->stripe_lock);
1481 
1482 	if (grow_buffers(sh)) {
1483 		shrink_buffers(sh);
1484 		kmem_cache_free(conf->slab_cache, sh);
1485 		return 0;
1486 	}
1487 	/* we just created an active stripe so... */
1488 	atomic_set(&sh->count, 1);
1489 	atomic_inc(&conf->active_stripes);
1490 	INIT_LIST_HEAD(&sh->lru);
1491 	release_stripe(sh);
1492 	return 1;
1493 }
1494 
1495 static int grow_stripes(struct r5conf *conf, int num)
1496 {
1497 	struct kmem_cache *sc;
1498 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
1499 
1500 	if (conf->mddev->gendisk)
1501 		sprintf(conf->cache_name[0],
1502 			"raid%d-%s", conf->level, mdname(conf->mddev));
1503 	else
1504 		sprintf(conf->cache_name[0],
1505 			"raid%d-%p", conf->level, conf->mddev);
1506 	sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1507 
1508 	conf->active_name = 0;
1509 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
1510 			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1511 			       0, 0, NULL);
1512 	if (!sc)
1513 		return 1;
1514 	conf->slab_cache = sc;
1515 	conf->pool_size = devs;
1516 	while (num--)
1517 		if (!grow_one_stripe(conf))
1518 			return 1;
1519 	return 0;
1520 }
1521 
1522 /**
1523  * scribble_len - return the required size of the scribble region
1524  * @num - total number of disks in the array
1525  *
1526  * The size must be enough to contain:
1527  * 1/ a struct page pointer for each device in the array +2
1528  * 2/ room to convert each entry in (1) to its corresponding dma
1529  *    (dma_map_page()) or page (page_address()) address.
1530  *
1531  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1532  * calculate over all devices (not just the data blocks), using zeros in place
1533  * of the P and Q blocks.
1534  */
1535 static size_t scribble_len(int num)
1536 {
1537 	size_t len;
1538 
1539 	len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1540 
1541 	return len;
1542 }
1543 
1544 static int resize_stripes(struct r5conf *conf, int newsize)
1545 {
1546 	/* Make all the stripes able to hold 'newsize' devices.
1547 	 * New slots in each stripe get 'page' set to a new page.
1548 	 *
1549 	 * This happens in stages:
1550 	 * 1/ create a new kmem_cache and allocate the required number of
1551 	 *    stripe_heads.
1552 	 * 2/ gather all the old stripe_heads and transfer the pages across
1553 	 *    to the new stripe_heads.  This will have the side effect of
1554 	 *    freezing the array as once all stripe_heads have been collected,
1555 	 *    no IO will be possible.  Old stripe heads are freed once their
1556 	 *    pages have been transferred over, and the old kmem_cache is
1557 	 *    freed when all stripes are done.
1558 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1559 	 *    we simple return a failre status - no need to clean anything up.
1560 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
1561 	 *    If this fails, we don't bother trying the shrink the
1562 	 *    stripe_heads down again, we just leave them as they are.
1563 	 *    As each stripe_head is processed the new one is released into
1564 	 *    active service.
1565 	 *
1566 	 * Once step2 is started, we cannot afford to wait for a write,
1567 	 * so we use GFP_NOIO allocations.
1568 	 */
1569 	struct stripe_head *osh, *nsh;
1570 	LIST_HEAD(newstripes);
1571 	struct disk_info *ndisks;
1572 	unsigned long cpu;
1573 	int err;
1574 	struct kmem_cache *sc;
1575 	int i;
1576 
1577 	if (newsize <= conf->pool_size)
1578 		return 0; /* never bother to shrink */
1579 
1580 	err = md_allow_write(conf->mddev);
1581 	if (err)
1582 		return err;
1583 
1584 	/* Step 1 */
1585 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1586 			       sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1587 			       0, 0, NULL);
1588 	if (!sc)
1589 		return -ENOMEM;
1590 
1591 	for (i = conf->max_nr_stripes; i; i--) {
1592 		nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1593 		if (!nsh)
1594 			break;
1595 
1596 		nsh->raid_conf = conf;
1597 		spin_lock_init(&nsh->stripe_lock);
1598 
1599 		list_add(&nsh->lru, &newstripes);
1600 	}
1601 	if (i) {
1602 		/* didn't get enough, give up */
1603 		while (!list_empty(&newstripes)) {
1604 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
1605 			list_del(&nsh->lru);
1606 			kmem_cache_free(sc, nsh);
1607 		}
1608 		kmem_cache_destroy(sc);
1609 		return -ENOMEM;
1610 	}
1611 	/* Step 2 - Must use GFP_NOIO now.
1612 	 * OK, we have enough stripes, start collecting inactive
1613 	 * stripes and copying them over
1614 	 */
1615 	list_for_each_entry(nsh, &newstripes, lru) {
1616 		spin_lock_irq(&conf->device_lock);
1617 		wait_event_lock_irq(conf->wait_for_stripe,
1618 				    !list_empty(&conf->inactive_list),
1619 				    conf->device_lock);
1620 		osh = get_free_stripe(conf);
1621 		spin_unlock_irq(&conf->device_lock);
1622 		atomic_set(&nsh->count, 1);
1623 		for(i=0; i<conf->pool_size; i++)
1624 			nsh->dev[i].page = osh->dev[i].page;
1625 		for( ; i<newsize; i++)
1626 			nsh->dev[i].page = NULL;
1627 		kmem_cache_free(conf->slab_cache, osh);
1628 	}
1629 	kmem_cache_destroy(conf->slab_cache);
1630 
1631 	/* Step 3.
1632 	 * At this point, we are holding all the stripes so the array
1633 	 * is completely stalled, so now is a good time to resize
1634 	 * conf->disks and the scribble region
1635 	 */
1636 	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1637 	if (ndisks) {
1638 		for (i=0; i<conf->raid_disks; i++)
1639 			ndisks[i] = conf->disks[i];
1640 		kfree(conf->disks);
1641 		conf->disks = ndisks;
1642 	} else
1643 		err = -ENOMEM;
1644 
1645 	get_online_cpus();
1646 	conf->scribble_len = scribble_len(newsize);
1647 	for_each_present_cpu(cpu) {
1648 		struct raid5_percpu *percpu;
1649 		void *scribble;
1650 
1651 		percpu = per_cpu_ptr(conf->percpu, cpu);
1652 		scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1653 
1654 		if (scribble) {
1655 			kfree(percpu->scribble);
1656 			percpu->scribble = scribble;
1657 		} else {
1658 			err = -ENOMEM;
1659 			break;
1660 		}
1661 	}
1662 	put_online_cpus();
1663 
1664 	/* Step 4, return new stripes to service */
1665 	while(!list_empty(&newstripes)) {
1666 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
1667 		list_del_init(&nsh->lru);
1668 
1669 		for (i=conf->raid_disks; i < newsize; i++)
1670 			if (nsh->dev[i].page == NULL) {
1671 				struct page *p = alloc_page(GFP_NOIO);
1672 				nsh->dev[i].page = p;
1673 				if (!p)
1674 					err = -ENOMEM;
1675 			}
1676 		release_stripe(nsh);
1677 	}
1678 	/* critical section pass, GFP_NOIO no longer needed */
1679 
1680 	conf->slab_cache = sc;
1681 	conf->active_name = 1-conf->active_name;
1682 	conf->pool_size = newsize;
1683 	return err;
1684 }
1685 
1686 static int drop_one_stripe(struct r5conf *conf)
1687 {
1688 	struct stripe_head *sh;
1689 
1690 	spin_lock_irq(&conf->device_lock);
1691 	sh = get_free_stripe(conf);
1692 	spin_unlock_irq(&conf->device_lock);
1693 	if (!sh)
1694 		return 0;
1695 	BUG_ON(atomic_read(&sh->count));
1696 	shrink_buffers(sh);
1697 	kmem_cache_free(conf->slab_cache, sh);
1698 	atomic_dec(&conf->active_stripes);
1699 	return 1;
1700 }
1701 
1702 static void shrink_stripes(struct r5conf *conf)
1703 {
1704 	while (drop_one_stripe(conf))
1705 		;
1706 
1707 	if (conf->slab_cache)
1708 		kmem_cache_destroy(conf->slab_cache);
1709 	conf->slab_cache = NULL;
1710 }
1711 
1712 static void raid5_end_read_request(struct bio * bi, int error)
1713 {
1714 	struct stripe_head *sh = bi->bi_private;
1715 	struct r5conf *conf = sh->raid_conf;
1716 	int disks = sh->disks, i;
1717 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1718 	char b[BDEVNAME_SIZE];
1719 	struct md_rdev *rdev = NULL;
1720 	sector_t s;
1721 
1722 	for (i=0 ; i<disks; i++)
1723 		if (bi == &sh->dev[i].req)
1724 			break;
1725 
1726 	pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1727 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
1728 		uptodate);
1729 	if (i == disks) {
1730 		BUG();
1731 		return;
1732 	}
1733 	if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1734 		/* If replacement finished while this request was outstanding,
1735 		 * 'replacement' might be NULL already.
1736 		 * In that case it moved down to 'rdev'.
1737 		 * rdev is not removed until all requests are finished.
1738 		 */
1739 		rdev = conf->disks[i].replacement;
1740 	if (!rdev)
1741 		rdev = conf->disks[i].rdev;
1742 
1743 	if (use_new_offset(conf, sh))
1744 		s = sh->sector + rdev->new_data_offset;
1745 	else
1746 		s = sh->sector + rdev->data_offset;
1747 	if (uptodate) {
1748 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
1749 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1750 			/* Note that this cannot happen on a
1751 			 * replacement device.  We just fail those on
1752 			 * any error
1753 			 */
1754 			printk_ratelimited(
1755 				KERN_INFO
1756 				"md/raid:%s: read error corrected"
1757 				" (%lu sectors at %llu on %s)\n",
1758 				mdname(conf->mddev), STRIPE_SECTORS,
1759 				(unsigned long long)s,
1760 				bdevname(rdev->bdev, b));
1761 			atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1762 			clear_bit(R5_ReadError, &sh->dev[i].flags);
1763 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
1764 		} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
1765 			clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1766 
1767 		if (atomic_read(&rdev->read_errors))
1768 			atomic_set(&rdev->read_errors, 0);
1769 	} else {
1770 		const char *bdn = bdevname(rdev->bdev, b);
1771 		int retry = 0;
1772 		int set_bad = 0;
1773 
1774 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1775 		atomic_inc(&rdev->read_errors);
1776 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1777 			printk_ratelimited(
1778 				KERN_WARNING
1779 				"md/raid:%s: read error on replacement device "
1780 				"(sector %llu on %s).\n",
1781 				mdname(conf->mddev),
1782 				(unsigned long long)s,
1783 				bdn);
1784 		else if (conf->mddev->degraded >= conf->max_degraded) {
1785 			set_bad = 1;
1786 			printk_ratelimited(
1787 				KERN_WARNING
1788 				"md/raid:%s: read error not correctable "
1789 				"(sector %llu on %s).\n",
1790 				mdname(conf->mddev),
1791 				(unsigned long long)s,
1792 				bdn);
1793 		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
1794 			/* Oh, no!!! */
1795 			set_bad = 1;
1796 			printk_ratelimited(
1797 				KERN_WARNING
1798 				"md/raid:%s: read error NOT corrected!! "
1799 				"(sector %llu on %s).\n",
1800 				mdname(conf->mddev),
1801 				(unsigned long long)s,
1802 				bdn);
1803 		} else if (atomic_read(&rdev->read_errors)
1804 			 > conf->max_nr_stripes)
1805 			printk(KERN_WARNING
1806 			       "md/raid:%s: Too many read errors, failing device %s.\n",
1807 			       mdname(conf->mddev), bdn);
1808 		else
1809 			retry = 1;
1810 		if (retry)
1811 			if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
1812 				set_bit(R5_ReadError, &sh->dev[i].flags);
1813 				clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1814 			} else
1815 				set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1816 		else {
1817 			clear_bit(R5_ReadError, &sh->dev[i].flags);
1818 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
1819 			if (!(set_bad
1820 			      && test_bit(In_sync, &rdev->flags)
1821 			      && rdev_set_badblocks(
1822 				      rdev, sh->sector, STRIPE_SECTORS, 0)))
1823 				md_error(conf->mddev, rdev);
1824 		}
1825 	}
1826 	rdev_dec_pending(rdev, conf->mddev);
1827 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
1828 	set_bit(STRIPE_HANDLE, &sh->state);
1829 	release_stripe(sh);
1830 }
1831 
1832 static void raid5_end_write_request(struct bio *bi, int error)
1833 {
1834 	struct stripe_head *sh = bi->bi_private;
1835 	struct r5conf *conf = sh->raid_conf;
1836 	int disks = sh->disks, i;
1837 	struct md_rdev *uninitialized_var(rdev);
1838 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1839 	sector_t first_bad;
1840 	int bad_sectors;
1841 	int replacement = 0;
1842 
1843 	for (i = 0 ; i < disks; i++) {
1844 		if (bi == &sh->dev[i].req) {
1845 			rdev = conf->disks[i].rdev;
1846 			break;
1847 		}
1848 		if (bi == &sh->dev[i].rreq) {
1849 			rdev = conf->disks[i].replacement;
1850 			if (rdev)
1851 				replacement = 1;
1852 			else
1853 				/* rdev was removed and 'replacement'
1854 				 * replaced it.  rdev is not removed
1855 				 * until all requests are finished.
1856 				 */
1857 				rdev = conf->disks[i].rdev;
1858 			break;
1859 		}
1860 	}
1861 	pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1862 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
1863 		uptodate);
1864 	if (i == disks) {
1865 		BUG();
1866 		return;
1867 	}
1868 
1869 	if (replacement) {
1870 		if (!uptodate)
1871 			md_error(conf->mddev, rdev);
1872 		else if (is_badblock(rdev, sh->sector,
1873 				     STRIPE_SECTORS,
1874 				     &first_bad, &bad_sectors))
1875 			set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
1876 	} else {
1877 		if (!uptodate) {
1878 			set_bit(WriteErrorSeen, &rdev->flags);
1879 			set_bit(R5_WriteError, &sh->dev[i].flags);
1880 			if (!test_and_set_bit(WantReplacement, &rdev->flags))
1881 				set_bit(MD_RECOVERY_NEEDED,
1882 					&rdev->mddev->recovery);
1883 		} else if (is_badblock(rdev, sh->sector,
1884 				       STRIPE_SECTORS,
1885 				       &first_bad, &bad_sectors))
1886 			set_bit(R5_MadeGood, &sh->dev[i].flags);
1887 	}
1888 	rdev_dec_pending(rdev, conf->mddev);
1889 
1890 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
1891 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
1892 	set_bit(STRIPE_HANDLE, &sh->state);
1893 	release_stripe(sh);
1894 }
1895 
1896 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1897 
1898 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1899 {
1900 	struct r5dev *dev = &sh->dev[i];
1901 
1902 	bio_init(&dev->req);
1903 	dev->req.bi_io_vec = &dev->vec;
1904 	dev->req.bi_vcnt++;
1905 	dev->req.bi_max_vecs++;
1906 	dev->req.bi_private = sh;
1907 	dev->vec.bv_page = dev->page;
1908 
1909 	bio_init(&dev->rreq);
1910 	dev->rreq.bi_io_vec = &dev->rvec;
1911 	dev->rreq.bi_vcnt++;
1912 	dev->rreq.bi_max_vecs++;
1913 	dev->rreq.bi_private = sh;
1914 	dev->rvec.bv_page = dev->page;
1915 
1916 	dev->flags = 0;
1917 	dev->sector = compute_blocknr(sh, i, previous);
1918 }
1919 
1920 static void error(struct mddev *mddev, struct md_rdev *rdev)
1921 {
1922 	char b[BDEVNAME_SIZE];
1923 	struct r5conf *conf = mddev->private;
1924 	unsigned long flags;
1925 	pr_debug("raid456: error called\n");
1926 
1927 	spin_lock_irqsave(&conf->device_lock, flags);
1928 	clear_bit(In_sync, &rdev->flags);
1929 	mddev->degraded = calc_degraded(conf);
1930 	spin_unlock_irqrestore(&conf->device_lock, flags);
1931 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1932 
1933 	set_bit(Blocked, &rdev->flags);
1934 	set_bit(Faulty, &rdev->flags);
1935 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
1936 	printk(KERN_ALERT
1937 	       "md/raid:%s: Disk failure on %s, disabling device.\n"
1938 	       "md/raid:%s: Operation continuing on %d devices.\n",
1939 	       mdname(mddev),
1940 	       bdevname(rdev->bdev, b),
1941 	       mdname(mddev),
1942 	       conf->raid_disks - mddev->degraded);
1943 }
1944 
1945 /*
1946  * Input: a 'big' sector number,
1947  * Output: index of the data and parity disk, and the sector # in them.
1948  */
1949 static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
1950 				     int previous, int *dd_idx,
1951 				     struct stripe_head *sh)
1952 {
1953 	sector_t stripe, stripe2;
1954 	sector_t chunk_number;
1955 	unsigned int chunk_offset;
1956 	int pd_idx, qd_idx;
1957 	int ddf_layout = 0;
1958 	sector_t new_sector;
1959 	int algorithm = previous ? conf->prev_algo
1960 				 : conf->algorithm;
1961 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1962 					 : conf->chunk_sectors;
1963 	int raid_disks = previous ? conf->previous_raid_disks
1964 				  : conf->raid_disks;
1965 	int data_disks = raid_disks - conf->max_degraded;
1966 
1967 	/* First compute the information on this sector */
1968 
1969 	/*
1970 	 * Compute the chunk number and the sector offset inside the chunk
1971 	 */
1972 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
1973 	chunk_number = r_sector;
1974 
1975 	/*
1976 	 * Compute the stripe number
1977 	 */
1978 	stripe = chunk_number;
1979 	*dd_idx = sector_div(stripe, data_disks);
1980 	stripe2 = stripe;
1981 	/*
1982 	 * Select the parity disk based on the user selected algorithm.
1983 	 */
1984 	pd_idx = qd_idx = -1;
1985 	switch(conf->level) {
1986 	case 4:
1987 		pd_idx = data_disks;
1988 		break;
1989 	case 5:
1990 		switch (algorithm) {
1991 		case ALGORITHM_LEFT_ASYMMETRIC:
1992 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
1993 			if (*dd_idx >= pd_idx)
1994 				(*dd_idx)++;
1995 			break;
1996 		case ALGORITHM_RIGHT_ASYMMETRIC:
1997 			pd_idx = sector_div(stripe2, raid_disks);
1998 			if (*dd_idx >= pd_idx)
1999 				(*dd_idx)++;
2000 			break;
2001 		case ALGORITHM_LEFT_SYMMETRIC:
2002 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2003 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2004 			break;
2005 		case ALGORITHM_RIGHT_SYMMETRIC:
2006 			pd_idx = sector_div(stripe2, raid_disks);
2007 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2008 			break;
2009 		case ALGORITHM_PARITY_0:
2010 			pd_idx = 0;
2011 			(*dd_idx)++;
2012 			break;
2013 		case ALGORITHM_PARITY_N:
2014 			pd_idx = data_disks;
2015 			break;
2016 		default:
2017 			BUG();
2018 		}
2019 		break;
2020 	case 6:
2021 
2022 		switch (algorithm) {
2023 		case ALGORITHM_LEFT_ASYMMETRIC:
2024 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2025 			qd_idx = pd_idx + 1;
2026 			if (pd_idx == raid_disks-1) {
2027 				(*dd_idx)++;	/* Q D D D P */
2028 				qd_idx = 0;
2029 			} else if (*dd_idx >= pd_idx)
2030 				(*dd_idx) += 2; /* D D P Q D */
2031 			break;
2032 		case ALGORITHM_RIGHT_ASYMMETRIC:
2033 			pd_idx = sector_div(stripe2, raid_disks);
2034 			qd_idx = pd_idx + 1;
2035 			if (pd_idx == raid_disks-1) {
2036 				(*dd_idx)++;	/* Q D D D P */
2037 				qd_idx = 0;
2038 			} else if (*dd_idx >= pd_idx)
2039 				(*dd_idx) += 2; /* D D P Q D */
2040 			break;
2041 		case ALGORITHM_LEFT_SYMMETRIC:
2042 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2043 			qd_idx = (pd_idx + 1) % raid_disks;
2044 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2045 			break;
2046 		case ALGORITHM_RIGHT_SYMMETRIC:
2047 			pd_idx = sector_div(stripe2, raid_disks);
2048 			qd_idx = (pd_idx + 1) % raid_disks;
2049 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2050 			break;
2051 
2052 		case ALGORITHM_PARITY_0:
2053 			pd_idx = 0;
2054 			qd_idx = 1;
2055 			(*dd_idx) += 2;
2056 			break;
2057 		case ALGORITHM_PARITY_N:
2058 			pd_idx = data_disks;
2059 			qd_idx = data_disks + 1;
2060 			break;
2061 
2062 		case ALGORITHM_ROTATING_ZERO_RESTART:
2063 			/* Exactly the same as RIGHT_ASYMMETRIC, but or
2064 			 * of blocks for computing Q is different.
2065 			 */
2066 			pd_idx = sector_div(stripe2, raid_disks);
2067 			qd_idx = pd_idx + 1;
2068 			if (pd_idx == raid_disks-1) {
2069 				(*dd_idx)++;	/* Q D D D P */
2070 				qd_idx = 0;
2071 			} else if (*dd_idx >= pd_idx)
2072 				(*dd_idx) += 2; /* D D P Q D */
2073 			ddf_layout = 1;
2074 			break;
2075 
2076 		case ALGORITHM_ROTATING_N_RESTART:
2077 			/* Same a left_asymmetric, by first stripe is
2078 			 * D D D P Q  rather than
2079 			 * Q D D D P
2080 			 */
2081 			stripe2 += 1;
2082 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2083 			qd_idx = pd_idx + 1;
2084 			if (pd_idx == raid_disks-1) {
2085 				(*dd_idx)++;	/* Q D D D P */
2086 				qd_idx = 0;
2087 			} else if (*dd_idx >= pd_idx)
2088 				(*dd_idx) += 2; /* D D P Q D */
2089 			ddf_layout = 1;
2090 			break;
2091 
2092 		case ALGORITHM_ROTATING_N_CONTINUE:
2093 			/* Same as left_symmetric but Q is before P */
2094 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2095 			qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2096 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2097 			ddf_layout = 1;
2098 			break;
2099 
2100 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2101 			/* RAID5 left_asymmetric, with Q on last device */
2102 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2103 			if (*dd_idx >= pd_idx)
2104 				(*dd_idx)++;
2105 			qd_idx = raid_disks - 1;
2106 			break;
2107 
2108 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2109 			pd_idx = sector_div(stripe2, raid_disks-1);
2110 			if (*dd_idx >= pd_idx)
2111 				(*dd_idx)++;
2112 			qd_idx = raid_disks - 1;
2113 			break;
2114 
2115 		case ALGORITHM_LEFT_SYMMETRIC_6:
2116 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2117 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2118 			qd_idx = raid_disks - 1;
2119 			break;
2120 
2121 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2122 			pd_idx = sector_div(stripe2, raid_disks-1);
2123 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2124 			qd_idx = raid_disks - 1;
2125 			break;
2126 
2127 		case ALGORITHM_PARITY_0_6:
2128 			pd_idx = 0;
2129 			(*dd_idx)++;
2130 			qd_idx = raid_disks - 1;
2131 			break;
2132 
2133 		default:
2134 			BUG();
2135 		}
2136 		break;
2137 	}
2138 
2139 	if (sh) {
2140 		sh->pd_idx = pd_idx;
2141 		sh->qd_idx = qd_idx;
2142 		sh->ddf_layout = ddf_layout;
2143 	}
2144 	/*
2145 	 * Finally, compute the new sector number
2146 	 */
2147 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2148 	return new_sector;
2149 }
2150 
2151 
2152 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2153 {
2154 	struct r5conf *conf = sh->raid_conf;
2155 	int raid_disks = sh->disks;
2156 	int data_disks = raid_disks - conf->max_degraded;
2157 	sector_t new_sector = sh->sector, check;
2158 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2159 					 : conf->chunk_sectors;
2160 	int algorithm = previous ? conf->prev_algo
2161 				 : conf->algorithm;
2162 	sector_t stripe;
2163 	int chunk_offset;
2164 	sector_t chunk_number;
2165 	int dummy1, dd_idx = i;
2166 	sector_t r_sector;
2167 	struct stripe_head sh2;
2168 
2169 
2170 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
2171 	stripe = new_sector;
2172 
2173 	if (i == sh->pd_idx)
2174 		return 0;
2175 	switch(conf->level) {
2176 	case 4: break;
2177 	case 5:
2178 		switch (algorithm) {
2179 		case ALGORITHM_LEFT_ASYMMETRIC:
2180 		case ALGORITHM_RIGHT_ASYMMETRIC:
2181 			if (i > sh->pd_idx)
2182 				i--;
2183 			break;
2184 		case ALGORITHM_LEFT_SYMMETRIC:
2185 		case ALGORITHM_RIGHT_SYMMETRIC:
2186 			if (i < sh->pd_idx)
2187 				i += raid_disks;
2188 			i -= (sh->pd_idx + 1);
2189 			break;
2190 		case ALGORITHM_PARITY_0:
2191 			i -= 1;
2192 			break;
2193 		case ALGORITHM_PARITY_N:
2194 			break;
2195 		default:
2196 			BUG();
2197 		}
2198 		break;
2199 	case 6:
2200 		if (i == sh->qd_idx)
2201 			return 0; /* It is the Q disk */
2202 		switch (algorithm) {
2203 		case ALGORITHM_LEFT_ASYMMETRIC:
2204 		case ALGORITHM_RIGHT_ASYMMETRIC:
2205 		case ALGORITHM_ROTATING_ZERO_RESTART:
2206 		case ALGORITHM_ROTATING_N_RESTART:
2207 			if (sh->pd_idx == raid_disks-1)
2208 				i--;	/* Q D D D P */
2209 			else if (i > sh->pd_idx)
2210 				i -= 2; /* D D P Q D */
2211 			break;
2212 		case ALGORITHM_LEFT_SYMMETRIC:
2213 		case ALGORITHM_RIGHT_SYMMETRIC:
2214 			if (sh->pd_idx == raid_disks-1)
2215 				i--; /* Q D D D P */
2216 			else {
2217 				/* D D P Q D */
2218 				if (i < sh->pd_idx)
2219 					i += raid_disks;
2220 				i -= (sh->pd_idx + 2);
2221 			}
2222 			break;
2223 		case ALGORITHM_PARITY_0:
2224 			i -= 2;
2225 			break;
2226 		case ALGORITHM_PARITY_N:
2227 			break;
2228 		case ALGORITHM_ROTATING_N_CONTINUE:
2229 			/* Like left_symmetric, but P is before Q */
2230 			if (sh->pd_idx == 0)
2231 				i--;	/* P D D D Q */
2232 			else {
2233 				/* D D Q P D */
2234 				if (i < sh->pd_idx)
2235 					i += raid_disks;
2236 				i -= (sh->pd_idx + 1);
2237 			}
2238 			break;
2239 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2240 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2241 			if (i > sh->pd_idx)
2242 				i--;
2243 			break;
2244 		case ALGORITHM_LEFT_SYMMETRIC_6:
2245 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2246 			if (i < sh->pd_idx)
2247 				i += data_disks + 1;
2248 			i -= (sh->pd_idx + 1);
2249 			break;
2250 		case ALGORITHM_PARITY_0_6:
2251 			i -= 1;
2252 			break;
2253 		default:
2254 			BUG();
2255 		}
2256 		break;
2257 	}
2258 
2259 	chunk_number = stripe * data_disks + i;
2260 	r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2261 
2262 	check = raid5_compute_sector(conf, r_sector,
2263 				     previous, &dummy1, &sh2);
2264 	if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2265 		|| sh2.qd_idx != sh->qd_idx) {
2266 		printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2267 		       mdname(conf->mddev));
2268 		return 0;
2269 	}
2270 	return r_sector;
2271 }
2272 
2273 
2274 static void
2275 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2276 			 int rcw, int expand)
2277 {
2278 	int i, pd_idx = sh->pd_idx, disks = sh->disks;
2279 	struct r5conf *conf = sh->raid_conf;
2280 	int level = conf->level;
2281 
2282 	if (rcw) {
2283 		/* if we are not expanding this is a proper write request, and
2284 		 * there will be bios with new data to be drained into the
2285 		 * stripe cache
2286 		 */
2287 		if (!expand) {
2288 			sh->reconstruct_state = reconstruct_state_drain_run;
2289 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2290 		} else
2291 			sh->reconstruct_state = reconstruct_state_run;
2292 
2293 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2294 
2295 		for (i = disks; i--; ) {
2296 			struct r5dev *dev = &sh->dev[i];
2297 
2298 			if (dev->towrite) {
2299 				set_bit(R5_LOCKED, &dev->flags);
2300 				set_bit(R5_Wantdrain, &dev->flags);
2301 				if (!expand)
2302 					clear_bit(R5_UPTODATE, &dev->flags);
2303 				s->locked++;
2304 			}
2305 		}
2306 		if (s->locked + conf->max_degraded == disks)
2307 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2308 				atomic_inc(&conf->pending_full_writes);
2309 	} else {
2310 		BUG_ON(level == 6);
2311 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2312 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2313 
2314 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2315 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2316 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2317 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2318 
2319 		for (i = disks; i--; ) {
2320 			struct r5dev *dev = &sh->dev[i];
2321 			if (i == pd_idx)
2322 				continue;
2323 
2324 			if (dev->towrite &&
2325 			    (test_bit(R5_UPTODATE, &dev->flags) ||
2326 			     test_bit(R5_Wantcompute, &dev->flags))) {
2327 				set_bit(R5_Wantdrain, &dev->flags);
2328 				set_bit(R5_LOCKED, &dev->flags);
2329 				clear_bit(R5_UPTODATE, &dev->flags);
2330 				s->locked++;
2331 			}
2332 		}
2333 	}
2334 
2335 	/* keep the parity disk(s) locked while asynchronous operations
2336 	 * are in flight
2337 	 */
2338 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2339 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2340 	s->locked++;
2341 
2342 	if (level == 6) {
2343 		int qd_idx = sh->qd_idx;
2344 		struct r5dev *dev = &sh->dev[qd_idx];
2345 
2346 		set_bit(R5_LOCKED, &dev->flags);
2347 		clear_bit(R5_UPTODATE, &dev->flags);
2348 		s->locked++;
2349 	}
2350 
2351 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2352 		__func__, (unsigned long long)sh->sector,
2353 		s->locked, s->ops_request);
2354 }
2355 
2356 /*
2357  * Each stripe/dev can have one or more bion attached.
2358  * toread/towrite point to the first in a chain.
2359  * The bi_next chain must be in order.
2360  */
2361 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2362 {
2363 	struct bio **bip;
2364 	struct r5conf *conf = sh->raid_conf;
2365 	int firstwrite=0;
2366 
2367 	pr_debug("adding bi b#%llu to stripe s#%llu\n",
2368 		(unsigned long long)bi->bi_sector,
2369 		(unsigned long long)sh->sector);
2370 
2371 	/*
2372 	 * If several bio share a stripe. The bio bi_phys_segments acts as a
2373 	 * reference count to avoid race. The reference count should already be
2374 	 * increased before this function is called (for example, in
2375 	 * make_request()), so other bio sharing this stripe will not free the
2376 	 * stripe. If a stripe is owned by one stripe, the stripe lock will
2377 	 * protect it.
2378 	 */
2379 	spin_lock_irq(&sh->stripe_lock);
2380 	if (forwrite) {
2381 		bip = &sh->dev[dd_idx].towrite;
2382 		if (*bip == NULL)
2383 			firstwrite = 1;
2384 	} else
2385 		bip = &sh->dev[dd_idx].toread;
2386 	while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2387 		if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
2388 			goto overlap;
2389 		bip = & (*bip)->bi_next;
2390 	}
2391 	if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
2392 		goto overlap;
2393 
2394 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2395 	if (*bip)
2396 		bi->bi_next = *bip;
2397 	*bip = bi;
2398 	raid5_inc_bi_active_stripes(bi);
2399 
2400 	if (forwrite) {
2401 		/* check if page is covered */
2402 		sector_t sector = sh->dev[dd_idx].sector;
2403 		for (bi=sh->dev[dd_idx].towrite;
2404 		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2405 			     bi && bi->bi_sector <= sector;
2406 		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2407 			if (bi->bi_sector + (bi->bi_size>>9) >= sector)
2408 				sector = bi->bi_sector + (bi->bi_size>>9);
2409 		}
2410 		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2411 			set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2412 	}
2413 
2414 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2415 		(unsigned long long)(*bip)->bi_sector,
2416 		(unsigned long long)sh->sector, dd_idx);
2417 	spin_unlock_irq(&sh->stripe_lock);
2418 
2419 	if (conf->mddev->bitmap && firstwrite) {
2420 		bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2421 				  STRIPE_SECTORS, 0);
2422 		sh->bm_seq = conf->seq_flush+1;
2423 		set_bit(STRIPE_BIT_DELAY, &sh->state);
2424 	}
2425 	return 1;
2426 
2427  overlap:
2428 	set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2429 	spin_unlock_irq(&sh->stripe_lock);
2430 	return 0;
2431 }
2432 
2433 static void end_reshape(struct r5conf *conf);
2434 
2435 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2436 			    struct stripe_head *sh)
2437 {
2438 	int sectors_per_chunk =
2439 		previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2440 	int dd_idx;
2441 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
2442 	int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2443 
2444 	raid5_compute_sector(conf,
2445 			     stripe * (disks - conf->max_degraded)
2446 			     *sectors_per_chunk + chunk_offset,
2447 			     previous,
2448 			     &dd_idx, sh);
2449 }
2450 
2451 static void
2452 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2453 				struct stripe_head_state *s, int disks,
2454 				struct bio **return_bi)
2455 {
2456 	int i;
2457 	for (i = disks; i--; ) {
2458 		struct bio *bi;
2459 		int bitmap_end = 0;
2460 
2461 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2462 			struct md_rdev *rdev;
2463 			rcu_read_lock();
2464 			rdev = rcu_dereference(conf->disks[i].rdev);
2465 			if (rdev && test_bit(In_sync, &rdev->flags))
2466 				atomic_inc(&rdev->nr_pending);
2467 			else
2468 				rdev = NULL;
2469 			rcu_read_unlock();
2470 			if (rdev) {
2471 				if (!rdev_set_badblocks(
2472 					    rdev,
2473 					    sh->sector,
2474 					    STRIPE_SECTORS, 0))
2475 					md_error(conf->mddev, rdev);
2476 				rdev_dec_pending(rdev, conf->mddev);
2477 			}
2478 		}
2479 		spin_lock_irq(&sh->stripe_lock);
2480 		/* fail all writes first */
2481 		bi = sh->dev[i].towrite;
2482 		sh->dev[i].towrite = NULL;
2483 		spin_unlock_irq(&sh->stripe_lock);
2484 		if (bi)
2485 			bitmap_end = 1;
2486 
2487 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2488 			wake_up(&conf->wait_for_overlap);
2489 
2490 		while (bi && bi->bi_sector <
2491 			sh->dev[i].sector + STRIPE_SECTORS) {
2492 			struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2493 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
2494 			if (!raid5_dec_bi_active_stripes(bi)) {
2495 				md_write_end(conf->mddev);
2496 				bi->bi_next = *return_bi;
2497 				*return_bi = bi;
2498 			}
2499 			bi = nextbi;
2500 		}
2501 		if (bitmap_end)
2502 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2503 				STRIPE_SECTORS, 0, 0);
2504 		bitmap_end = 0;
2505 		/* and fail all 'written' */
2506 		bi = sh->dev[i].written;
2507 		sh->dev[i].written = NULL;
2508 		if (bi) bitmap_end = 1;
2509 		while (bi && bi->bi_sector <
2510 		       sh->dev[i].sector + STRIPE_SECTORS) {
2511 			struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2512 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
2513 			if (!raid5_dec_bi_active_stripes(bi)) {
2514 				md_write_end(conf->mddev);
2515 				bi->bi_next = *return_bi;
2516 				*return_bi = bi;
2517 			}
2518 			bi = bi2;
2519 		}
2520 
2521 		/* fail any reads if this device is non-operational and
2522 		 * the data has not reached the cache yet.
2523 		 */
2524 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2525 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2526 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
2527 			spin_lock_irq(&sh->stripe_lock);
2528 			bi = sh->dev[i].toread;
2529 			sh->dev[i].toread = NULL;
2530 			spin_unlock_irq(&sh->stripe_lock);
2531 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2532 				wake_up(&conf->wait_for_overlap);
2533 			while (bi && bi->bi_sector <
2534 			       sh->dev[i].sector + STRIPE_SECTORS) {
2535 				struct bio *nextbi =
2536 					r5_next_bio(bi, sh->dev[i].sector);
2537 				clear_bit(BIO_UPTODATE, &bi->bi_flags);
2538 				if (!raid5_dec_bi_active_stripes(bi)) {
2539 					bi->bi_next = *return_bi;
2540 					*return_bi = bi;
2541 				}
2542 				bi = nextbi;
2543 			}
2544 		}
2545 		if (bitmap_end)
2546 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2547 					STRIPE_SECTORS, 0, 0);
2548 		/* If we were in the middle of a write the parity block might
2549 		 * still be locked - so just clear all R5_LOCKED flags
2550 		 */
2551 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2552 	}
2553 
2554 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2555 		if (atomic_dec_and_test(&conf->pending_full_writes))
2556 			md_wakeup_thread(conf->mddev->thread);
2557 }
2558 
2559 static void
2560 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2561 		   struct stripe_head_state *s)
2562 {
2563 	int abort = 0;
2564 	int i;
2565 
2566 	clear_bit(STRIPE_SYNCING, &sh->state);
2567 	s->syncing = 0;
2568 	s->replacing = 0;
2569 	/* There is nothing more to do for sync/check/repair.
2570 	 * Don't even need to abort as that is handled elsewhere
2571 	 * if needed, and not always wanted e.g. if there is a known
2572 	 * bad block here.
2573 	 * For recover/replace we need to record a bad block on all
2574 	 * non-sync devices, or abort the recovery
2575 	 */
2576 	if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2577 		/* During recovery devices cannot be removed, so
2578 		 * locking and refcounting of rdevs is not needed
2579 		 */
2580 		for (i = 0; i < conf->raid_disks; i++) {
2581 			struct md_rdev *rdev = conf->disks[i].rdev;
2582 			if (rdev
2583 			    && !test_bit(Faulty, &rdev->flags)
2584 			    && !test_bit(In_sync, &rdev->flags)
2585 			    && !rdev_set_badblocks(rdev, sh->sector,
2586 						   STRIPE_SECTORS, 0))
2587 				abort = 1;
2588 			rdev = conf->disks[i].replacement;
2589 			if (rdev
2590 			    && !test_bit(Faulty, &rdev->flags)
2591 			    && !test_bit(In_sync, &rdev->flags)
2592 			    && !rdev_set_badblocks(rdev, sh->sector,
2593 						   STRIPE_SECTORS, 0))
2594 				abort = 1;
2595 		}
2596 		if (abort)
2597 			conf->recovery_disabled =
2598 				conf->mddev->recovery_disabled;
2599 	}
2600 	md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2601 }
2602 
2603 static int want_replace(struct stripe_head *sh, int disk_idx)
2604 {
2605 	struct md_rdev *rdev;
2606 	int rv = 0;
2607 	/* Doing recovery so rcu locking not required */
2608 	rdev = sh->raid_conf->disks[disk_idx].replacement;
2609 	if (rdev
2610 	    && !test_bit(Faulty, &rdev->flags)
2611 	    && !test_bit(In_sync, &rdev->flags)
2612 	    && (rdev->recovery_offset <= sh->sector
2613 		|| rdev->mddev->recovery_cp <= sh->sector))
2614 		rv = 1;
2615 
2616 	return rv;
2617 }
2618 
2619 /* fetch_block - checks the given member device to see if its data needs
2620  * to be read or computed to satisfy a request.
2621  *
2622  * Returns 1 when no more member devices need to be checked, otherwise returns
2623  * 0 to tell the loop in handle_stripe_fill to continue
2624  */
2625 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2626 		       int disk_idx, int disks)
2627 {
2628 	struct r5dev *dev = &sh->dev[disk_idx];
2629 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2630 				  &sh->dev[s->failed_num[1]] };
2631 
2632 	/* is the data in this block needed, and can we get it? */
2633 	if (!test_bit(R5_LOCKED, &dev->flags) &&
2634 	    !test_bit(R5_UPTODATE, &dev->flags) &&
2635 	    (dev->toread ||
2636 	     (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2637 	     s->syncing || s->expanding ||
2638 	     (s->replacing && want_replace(sh, disk_idx)) ||
2639 	     (s->failed >= 1 && fdev[0]->toread) ||
2640 	     (s->failed >= 2 && fdev[1]->toread) ||
2641 	     (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2642 	      !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2643 	     (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
2644 		/* we would like to get this block, possibly by computing it,
2645 		 * otherwise read it if the backing disk is insync
2646 		 */
2647 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2648 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
2649 		if ((s->uptodate == disks - 1) &&
2650 		    (s->failed && (disk_idx == s->failed_num[0] ||
2651 				   disk_idx == s->failed_num[1]))) {
2652 			/* have disk failed, and we're requested to fetch it;
2653 			 * do compute it
2654 			 */
2655 			pr_debug("Computing stripe %llu block %d\n",
2656 			       (unsigned long long)sh->sector, disk_idx);
2657 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2658 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2659 			set_bit(R5_Wantcompute, &dev->flags);
2660 			sh->ops.target = disk_idx;
2661 			sh->ops.target2 = -1; /* no 2nd target */
2662 			s->req_compute = 1;
2663 			/* Careful: from this point on 'uptodate' is in the eye
2664 			 * of raid_run_ops which services 'compute' operations
2665 			 * before writes. R5_Wantcompute flags a block that will
2666 			 * be R5_UPTODATE by the time it is needed for a
2667 			 * subsequent operation.
2668 			 */
2669 			s->uptodate++;
2670 			return 1;
2671 		} else if (s->uptodate == disks-2 && s->failed >= 2) {
2672 			/* Computing 2-failure is *very* expensive; only
2673 			 * do it if failed >= 2
2674 			 */
2675 			int other;
2676 			for (other = disks; other--; ) {
2677 				if (other == disk_idx)
2678 					continue;
2679 				if (!test_bit(R5_UPTODATE,
2680 				      &sh->dev[other].flags))
2681 					break;
2682 			}
2683 			BUG_ON(other < 0);
2684 			pr_debug("Computing stripe %llu blocks %d,%d\n",
2685 			       (unsigned long long)sh->sector,
2686 			       disk_idx, other);
2687 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2688 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2689 			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2690 			set_bit(R5_Wantcompute, &sh->dev[other].flags);
2691 			sh->ops.target = disk_idx;
2692 			sh->ops.target2 = other;
2693 			s->uptodate += 2;
2694 			s->req_compute = 1;
2695 			return 1;
2696 		} else if (test_bit(R5_Insync, &dev->flags)) {
2697 			set_bit(R5_LOCKED, &dev->flags);
2698 			set_bit(R5_Wantread, &dev->flags);
2699 			s->locked++;
2700 			pr_debug("Reading block %d (sync=%d)\n",
2701 				disk_idx, s->syncing);
2702 		}
2703 	}
2704 
2705 	return 0;
2706 }
2707 
2708 /**
2709  * handle_stripe_fill - read or compute data to satisfy pending requests.
2710  */
2711 static void handle_stripe_fill(struct stripe_head *sh,
2712 			       struct stripe_head_state *s,
2713 			       int disks)
2714 {
2715 	int i;
2716 
2717 	/* look for blocks to read/compute, skip this if a compute
2718 	 * is already in flight, or if the stripe contents are in the
2719 	 * midst of changing due to a write
2720 	 */
2721 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2722 	    !sh->reconstruct_state)
2723 		for (i = disks; i--; )
2724 			if (fetch_block(sh, s, i, disks))
2725 				break;
2726 	set_bit(STRIPE_HANDLE, &sh->state);
2727 }
2728 
2729 
2730 /* handle_stripe_clean_event
2731  * any written block on an uptodate or failed drive can be returned.
2732  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2733  * never LOCKED, so we don't need to test 'failed' directly.
2734  */
2735 static void handle_stripe_clean_event(struct r5conf *conf,
2736 	struct stripe_head *sh, int disks, struct bio **return_bi)
2737 {
2738 	int i;
2739 	struct r5dev *dev;
2740 
2741 	for (i = disks; i--; )
2742 		if (sh->dev[i].written) {
2743 			dev = &sh->dev[i];
2744 			if (!test_bit(R5_LOCKED, &dev->flags) &&
2745 			    (test_bit(R5_UPTODATE, &dev->flags) ||
2746 			     test_bit(R5_Discard, &dev->flags))) {
2747 				/* We can return any write requests */
2748 				struct bio *wbi, *wbi2;
2749 				pr_debug("Return write for disc %d\n", i);
2750 				if (test_and_clear_bit(R5_Discard, &dev->flags))
2751 					clear_bit(R5_UPTODATE, &dev->flags);
2752 				wbi = dev->written;
2753 				dev->written = NULL;
2754 				while (wbi && wbi->bi_sector <
2755 					dev->sector + STRIPE_SECTORS) {
2756 					wbi2 = r5_next_bio(wbi, dev->sector);
2757 					if (!raid5_dec_bi_active_stripes(wbi)) {
2758 						md_write_end(conf->mddev);
2759 						wbi->bi_next = *return_bi;
2760 						*return_bi = wbi;
2761 					}
2762 					wbi = wbi2;
2763 				}
2764 				bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2765 						STRIPE_SECTORS,
2766 					 !test_bit(STRIPE_DEGRADED, &sh->state),
2767 						0);
2768 			}
2769 		} else if (test_bit(R5_Discard, &sh->dev[i].flags))
2770 			clear_bit(R5_Discard, &sh->dev[i].flags);
2771 
2772 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2773 		if (atomic_dec_and_test(&conf->pending_full_writes))
2774 			md_wakeup_thread(conf->mddev->thread);
2775 }
2776 
2777 static void handle_stripe_dirtying(struct r5conf *conf,
2778 				   struct stripe_head *sh,
2779 				   struct stripe_head_state *s,
2780 				   int disks)
2781 {
2782 	int rmw = 0, rcw = 0, i;
2783 	sector_t recovery_cp = conf->mddev->recovery_cp;
2784 
2785 	/* RAID6 requires 'rcw' in current implementation.
2786 	 * Otherwise, check whether resync is now happening or should start.
2787 	 * If yes, then the array is dirty (after unclean shutdown or
2788 	 * initial creation), so parity in some stripes might be inconsistent.
2789 	 * In this case, we need to always do reconstruct-write, to ensure
2790 	 * that in case of drive failure or read-error correction, we
2791 	 * generate correct data from the parity.
2792 	 */
2793 	if (conf->max_degraded == 2 ||
2794 	    (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
2795 		/* Calculate the real rcw later - for now make it
2796 		 * look like rcw is cheaper
2797 		 */
2798 		rcw = 1; rmw = 2;
2799 		pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
2800 			 conf->max_degraded, (unsigned long long)recovery_cp,
2801 			 (unsigned long long)sh->sector);
2802 	} else for (i = disks; i--; ) {
2803 		/* would I have to read this buffer for read_modify_write */
2804 		struct r5dev *dev = &sh->dev[i];
2805 		if ((dev->towrite || i == sh->pd_idx) &&
2806 		    !test_bit(R5_LOCKED, &dev->flags) &&
2807 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
2808 		      test_bit(R5_Wantcompute, &dev->flags))) {
2809 			if (test_bit(R5_Insync, &dev->flags))
2810 				rmw++;
2811 			else
2812 				rmw += 2*disks;  /* cannot read it */
2813 		}
2814 		/* Would I have to read this buffer for reconstruct_write */
2815 		if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2816 		    !test_bit(R5_LOCKED, &dev->flags) &&
2817 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
2818 		    test_bit(R5_Wantcompute, &dev->flags))) {
2819 			if (test_bit(R5_Insync, &dev->flags)) rcw++;
2820 			else
2821 				rcw += 2*disks;
2822 		}
2823 	}
2824 	pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2825 		(unsigned long long)sh->sector, rmw, rcw);
2826 	set_bit(STRIPE_HANDLE, &sh->state);
2827 	if (rmw < rcw && rmw > 0) {
2828 		/* prefer read-modify-write, but need to get some data */
2829 		blk_add_trace_msg(conf->mddev->queue, "raid5 rmw %llu %d",
2830 				  (unsigned long long)sh->sector, rmw);
2831 		for (i = disks; i--; ) {
2832 			struct r5dev *dev = &sh->dev[i];
2833 			if ((dev->towrite || i == sh->pd_idx) &&
2834 			    !test_bit(R5_LOCKED, &dev->flags) &&
2835 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
2836 			    test_bit(R5_Wantcompute, &dev->flags)) &&
2837 			    test_bit(R5_Insync, &dev->flags)) {
2838 				if (
2839 				  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2840 					pr_debug("Read_old block "
2841 						 "%d for r-m-w\n", i);
2842 					set_bit(R5_LOCKED, &dev->flags);
2843 					set_bit(R5_Wantread, &dev->flags);
2844 					s->locked++;
2845 				} else {
2846 					set_bit(STRIPE_DELAYED, &sh->state);
2847 					set_bit(STRIPE_HANDLE, &sh->state);
2848 				}
2849 			}
2850 		}
2851 	}
2852 	if (rcw <= rmw && rcw > 0) {
2853 		/* want reconstruct write, but need to get some data */
2854 		int qread =0;
2855 		rcw = 0;
2856 		for (i = disks; i--; ) {
2857 			struct r5dev *dev = &sh->dev[i];
2858 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2859 			    i != sh->pd_idx && i != sh->qd_idx &&
2860 			    !test_bit(R5_LOCKED, &dev->flags) &&
2861 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
2862 			      test_bit(R5_Wantcompute, &dev->flags))) {
2863 				rcw++;
2864 				if (!test_bit(R5_Insync, &dev->flags))
2865 					continue; /* it's a failed drive */
2866 				if (
2867 				  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2868 					pr_debug("Read_old block "
2869 						"%d for Reconstruct\n", i);
2870 					set_bit(R5_LOCKED, &dev->flags);
2871 					set_bit(R5_Wantread, &dev->flags);
2872 					s->locked++;
2873 					qread++;
2874 				} else {
2875 					set_bit(STRIPE_DELAYED, &sh->state);
2876 					set_bit(STRIPE_HANDLE, &sh->state);
2877 				}
2878 			}
2879 		}
2880 		if (rcw)
2881 			blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
2882 					  (unsigned long long)sh->sector,
2883 					  rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
2884 	}
2885 	/* now if nothing is locked, and if we have enough data,
2886 	 * we can start a write request
2887 	 */
2888 	/* since handle_stripe can be called at any time we need to handle the
2889 	 * case where a compute block operation has been submitted and then a
2890 	 * subsequent call wants to start a write request.  raid_run_ops only
2891 	 * handles the case where compute block and reconstruct are requested
2892 	 * simultaneously.  If this is not the case then new writes need to be
2893 	 * held off until the compute completes.
2894 	 */
2895 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2896 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2897 	    !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2898 		schedule_reconstruction(sh, s, rcw == 0, 0);
2899 }
2900 
2901 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
2902 				struct stripe_head_state *s, int disks)
2903 {
2904 	struct r5dev *dev = NULL;
2905 
2906 	set_bit(STRIPE_HANDLE, &sh->state);
2907 
2908 	switch (sh->check_state) {
2909 	case check_state_idle:
2910 		/* start a new check operation if there are no failures */
2911 		if (s->failed == 0) {
2912 			BUG_ON(s->uptodate != disks);
2913 			sh->check_state = check_state_run;
2914 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
2915 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2916 			s->uptodate--;
2917 			break;
2918 		}
2919 		dev = &sh->dev[s->failed_num[0]];
2920 		/* fall through */
2921 	case check_state_compute_result:
2922 		sh->check_state = check_state_idle;
2923 		if (!dev)
2924 			dev = &sh->dev[sh->pd_idx];
2925 
2926 		/* check that a write has not made the stripe insync */
2927 		if (test_bit(STRIPE_INSYNC, &sh->state))
2928 			break;
2929 
2930 		/* either failed parity check, or recovery is happening */
2931 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2932 		BUG_ON(s->uptodate != disks);
2933 
2934 		set_bit(R5_LOCKED, &dev->flags);
2935 		s->locked++;
2936 		set_bit(R5_Wantwrite, &dev->flags);
2937 
2938 		clear_bit(STRIPE_DEGRADED, &sh->state);
2939 		set_bit(STRIPE_INSYNC, &sh->state);
2940 		break;
2941 	case check_state_run:
2942 		break; /* we will be called again upon completion */
2943 	case check_state_check_result:
2944 		sh->check_state = check_state_idle;
2945 
2946 		/* if a failure occurred during the check operation, leave
2947 		 * STRIPE_INSYNC not set and let the stripe be handled again
2948 		 */
2949 		if (s->failed)
2950 			break;
2951 
2952 		/* handle a successful check operation, if parity is correct
2953 		 * we are done.  Otherwise update the mismatch count and repair
2954 		 * parity if !MD_RECOVERY_CHECK
2955 		 */
2956 		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
2957 			/* parity is correct (on disc,
2958 			 * not in buffer any more)
2959 			 */
2960 			set_bit(STRIPE_INSYNC, &sh->state);
2961 		else {
2962 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
2963 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2964 				/* don't try to repair!! */
2965 				set_bit(STRIPE_INSYNC, &sh->state);
2966 			else {
2967 				sh->check_state = check_state_compute_run;
2968 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2969 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2970 				set_bit(R5_Wantcompute,
2971 					&sh->dev[sh->pd_idx].flags);
2972 				sh->ops.target = sh->pd_idx;
2973 				sh->ops.target2 = -1;
2974 				s->uptodate++;
2975 			}
2976 		}
2977 		break;
2978 	case check_state_compute_run:
2979 		break;
2980 	default:
2981 		printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
2982 		       __func__, sh->check_state,
2983 		       (unsigned long long) sh->sector);
2984 		BUG();
2985 	}
2986 }
2987 
2988 
2989 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
2990 				  struct stripe_head_state *s,
2991 				  int disks)
2992 {
2993 	int pd_idx = sh->pd_idx;
2994 	int qd_idx = sh->qd_idx;
2995 	struct r5dev *dev;
2996 
2997 	set_bit(STRIPE_HANDLE, &sh->state);
2998 
2999 	BUG_ON(s->failed > 2);
3000 
3001 	/* Want to check and possibly repair P and Q.
3002 	 * However there could be one 'failed' device, in which
3003 	 * case we can only check one of them, possibly using the
3004 	 * other to generate missing data
3005 	 */
3006 
3007 	switch (sh->check_state) {
3008 	case check_state_idle:
3009 		/* start a new check operation if there are < 2 failures */
3010 		if (s->failed == s->q_failed) {
3011 			/* The only possible failed device holds Q, so it
3012 			 * makes sense to check P (If anything else were failed,
3013 			 * we would have used P to recreate it).
3014 			 */
3015 			sh->check_state = check_state_run;
3016 		}
3017 		if (!s->q_failed && s->failed < 2) {
3018 			/* Q is not failed, and we didn't use it to generate
3019 			 * anything, so it makes sense to check it
3020 			 */
3021 			if (sh->check_state == check_state_run)
3022 				sh->check_state = check_state_run_pq;
3023 			else
3024 				sh->check_state = check_state_run_q;
3025 		}
3026 
3027 		/* discard potentially stale zero_sum_result */
3028 		sh->ops.zero_sum_result = 0;
3029 
3030 		if (sh->check_state == check_state_run) {
3031 			/* async_xor_zero_sum destroys the contents of P */
3032 			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3033 			s->uptodate--;
3034 		}
3035 		if (sh->check_state >= check_state_run &&
3036 		    sh->check_state <= check_state_run_pq) {
3037 			/* async_syndrome_zero_sum preserves P and Q, so
3038 			 * no need to mark them !uptodate here
3039 			 */
3040 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3041 			break;
3042 		}
3043 
3044 		/* we have 2-disk failure */
3045 		BUG_ON(s->failed != 2);
3046 		/* fall through */
3047 	case check_state_compute_result:
3048 		sh->check_state = check_state_idle;
3049 
3050 		/* check that a write has not made the stripe insync */
3051 		if (test_bit(STRIPE_INSYNC, &sh->state))
3052 			break;
3053 
3054 		/* now write out any block on a failed drive,
3055 		 * or P or Q if they were recomputed
3056 		 */
3057 		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3058 		if (s->failed == 2) {
3059 			dev = &sh->dev[s->failed_num[1]];
3060 			s->locked++;
3061 			set_bit(R5_LOCKED, &dev->flags);
3062 			set_bit(R5_Wantwrite, &dev->flags);
3063 		}
3064 		if (s->failed >= 1) {
3065 			dev = &sh->dev[s->failed_num[0]];
3066 			s->locked++;
3067 			set_bit(R5_LOCKED, &dev->flags);
3068 			set_bit(R5_Wantwrite, &dev->flags);
3069 		}
3070 		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3071 			dev = &sh->dev[pd_idx];
3072 			s->locked++;
3073 			set_bit(R5_LOCKED, &dev->flags);
3074 			set_bit(R5_Wantwrite, &dev->flags);
3075 		}
3076 		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3077 			dev = &sh->dev[qd_idx];
3078 			s->locked++;
3079 			set_bit(R5_LOCKED, &dev->flags);
3080 			set_bit(R5_Wantwrite, &dev->flags);
3081 		}
3082 		clear_bit(STRIPE_DEGRADED, &sh->state);
3083 
3084 		set_bit(STRIPE_INSYNC, &sh->state);
3085 		break;
3086 	case check_state_run:
3087 	case check_state_run_q:
3088 	case check_state_run_pq:
3089 		break; /* we will be called again upon completion */
3090 	case check_state_check_result:
3091 		sh->check_state = check_state_idle;
3092 
3093 		/* handle a successful check operation, if parity is correct
3094 		 * we are done.  Otherwise update the mismatch count and repair
3095 		 * parity if !MD_RECOVERY_CHECK
3096 		 */
3097 		if (sh->ops.zero_sum_result == 0) {
3098 			/* both parities are correct */
3099 			if (!s->failed)
3100 				set_bit(STRIPE_INSYNC, &sh->state);
3101 			else {
3102 				/* in contrast to the raid5 case we can validate
3103 				 * parity, but still have a failure to write
3104 				 * back
3105 				 */
3106 				sh->check_state = check_state_compute_result;
3107 				/* Returning at this point means that we may go
3108 				 * off and bring p and/or q uptodate again so
3109 				 * we make sure to check zero_sum_result again
3110 				 * to verify if p or q need writeback
3111 				 */
3112 			}
3113 		} else {
3114 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3115 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3116 				/* don't try to repair!! */
3117 				set_bit(STRIPE_INSYNC, &sh->state);
3118 			else {
3119 				int *target = &sh->ops.target;
3120 
3121 				sh->ops.target = -1;
3122 				sh->ops.target2 = -1;
3123 				sh->check_state = check_state_compute_run;
3124 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3125 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3126 				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3127 					set_bit(R5_Wantcompute,
3128 						&sh->dev[pd_idx].flags);
3129 					*target = pd_idx;
3130 					target = &sh->ops.target2;
3131 					s->uptodate++;
3132 				}
3133 				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3134 					set_bit(R5_Wantcompute,
3135 						&sh->dev[qd_idx].flags);
3136 					*target = qd_idx;
3137 					s->uptodate++;
3138 				}
3139 			}
3140 		}
3141 		break;
3142 	case check_state_compute_run:
3143 		break;
3144 	default:
3145 		printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3146 		       __func__, sh->check_state,
3147 		       (unsigned long long) sh->sector);
3148 		BUG();
3149 	}
3150 }
3151 
3152 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3153 {
3154 	int i;
3155 
3156 	/* We have read all the blocks in this stripe and now we need to
3157 	 * copy some of them into a target stripe for expand.
3158 	 */
3159 	struct dma_async_tx_descriptor *tx = NULL;
3160 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3161 	for (i = 0; i < sh->disks; i++)
3162 		if (i != sh->pd_idx && i != sh->qd_idx) {
3163 			int dd_idx, j;
3164 			struct stripe_head *sh2;
3165 			struct async_submit_ctl submit;
3166 
3167 			sector_t bn = compute_blocknr(sh, i, 1);
3168 			sector_t s = raid5_compute_sector(conf, bn, 0,
3169 							  &dd_idx, NULL);
3170 			sh2 = get_active_stripe(conf, s, 0, 1, 1);
3171 			if (sh2 == NULL)
3172 				/* so far only the early blocks of this stripe
3173 				 * have been requested.  When later blocks
3174 				 * get requested, we will try again
3175 				 */
3176 				continue;
3177 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3178 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3179 				/* must have already done this block */
3180 				release_stripe(sh2);
3181 				continue;
3182 			}
3183 
3184 			/* place all the copies on one channel */
3185 			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3186 			tx = async_memcpy(sh2->dev[dd_idx].page,
3187 					  sh->dev[i].page, 0, 0, STRIPE_SIZE,
3188 					  &submit);
3189 
3190 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3191 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3192 			for (j = 0; j < conf->raid_disks; j++)
3193 				if (j != sh2->pd_idx &&
3194 				    j != sh2->qd_idx &&
3195 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
3196 					break;
3197 			if (j == conf->raid_disks) {
3198 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
3199 				set_bit(STRIPE_HANDLE, &sh2->state);
3200 			}
3201 			release_stripe(sh2);
3202 
3203 		}
3204 	/* done submitting copies, wait for them to complete */
3205 	async_tx_quiesce(&tx);
3206 }
3207 
3208 /*
3209  * handle_stripe - do things to a stripe.
3210  *
3211  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3212  * state of various bits to see what needs to be done.
3213  * Possible results:
3214  *    return some read requests which now have data
3215  *    return some write requests which are safely on storage
3216  *    schedule a read on some buffers
3217  *    schedule a write of some buffers
3218  *    return confirmation of parity correctness
3219  *
3220  */
3221 
3222 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3223 {
3224 	struct r5conf *conf = sh->raid_conf;
3225 	int disks = sh->disks;
3226 	struct r5dev *dev;
3227 	int i;
3228 	int do_recovery = 0;
3229 
3230 	memset(s, 0, sizeof(*s));
3231 
3232 	s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3233 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3234 	s->failed_num[0] = -1;
3235 	s->failed_num[1] = -1;
3236 
3237 	/* Now to look around and see what can be done */
3238 	rcu_read_lock();
3239 	for (i=disks; i--; ) {
3240 		struct md_rdev *rdev;
3241 		sector_t first_bad;
3242 		int bad_sectors;
3243 		int is_bad = 0;
3244 
3245 		dev = &sh->dev[i];
3246 
3247 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3248 			 i, dev->flags,
3249 			 dev->toread, dev->towrite, dev->written);
3250 		/* maybe we can reply to a read
3251 		 *
3252 		 * new wantfill requests are only permitted while
3253 		 * ops_complete_biofill is guaranteed to be inactive
3254 		 */
3255 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3256 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3257 			set_bit(R5_Wantfill, &dev->flags);
3258 
3259 		/* now count some things */
3260 		if (test_bit(R5_LOCKED, &dev->flags))
3261 			s->locked++;
3262 		if (test_bit(R5_UPTODATE, &dev->flags))
3263 			s->uptodate++;
3264 		if (test_bit(R5_Wantcompute, &dev->flags)) {
3265 			s->compute++;
3266 			BUG_ON(s->compute > 2);
3267 		}
3268 
3269 		if (test_bit(R5_Wantfill, &dev->flags))
3270 			s->to_fill++;
3271 		else if (dev->toread)
3272 			s->to_read++;
3273 		if (dev->towrite) {
3274 			s->to_write++;
3275 			if (!test_bit(R5_OVERWRITE, &dev->flags))
3276 				s->non_overwrite++;
3277 		}
3278 		if (dev->written)
3279 			s->written++;
3280 		/* Prefer to use the replacement for reads, but only
3281 		 * if it is recovered enough and has no bad blocks.
3282 		 */
3283 		rdev = rcu_dereference(conf->disks[i].replacement);
3284 		if (rdev && !test_bit(Faulty, &rdev->flags) &&
3285 		    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3286 		    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3287 				 &first_bad, &bad_sectors))
3288 			set_bit(R5_ReadRepl, &dev->flags);
3289 		else {
3290 			if (rdev)
3291 				set_bit(R5_NeedReplace, &dev->flags);
3292 			rdev = rcu_dereference(conf->disks[i].rdev);
3293 			clear_bit(R5_ReadRepl, &dev->flags);
3294 		}
3295 		if (rdev && test_bit(Faulty, &rdev->flags))
3296 			rdev = NULL;
3297 		if (rdev) {
3298 			is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3299 					     &first_bad, &bad_sectors);
3300 			if (s->blocked_rdev == NULL
3301 			    && (test_bit(Blocked, &rdev->flags)
3302 				|| is_bad < 0)) {
3303 				if (is_bad < 0)
3304 					set_bit(BlockedBadBlocks,
3305 						&rdev->flags);
3306 				s->blocked_rdev = rdev;
3307 				atomic_inc(&rdev->nr_pending);
3308 			}
3309 		}
3310 		clear_bit(R5_Insync, &dev->flags);
3311 		if (!rdev)
3312 			/* Not in-sync */;
3313 		else if (is_bad) {
3314 			/* also not in-sync */
3315 			if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3316 			    test_bit(R5_UPTODATE, &dev->flags)) {
3317 				/* treat as in-sync, but with a read error
3318 				 * which we can now try to correct
3319 				 */
3320 				set_bit(R5_Insync, &dev->flags);
3321 				set_bit(R5_ReadError, &dev->flags);
3322 			}
3323 		} else if (test_bit(In_sync, &rdev->flags))
3324 			set_bit(R5_Insync, &dev->flags);
3325 		else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3326 			/* in sync if before recovery_offset */
3327 			set_bit(R5_Insync, &dev->flags);
3328 		else if (test_bit(R5_UPTODATE, &dev->flags) &&
3329 			 test_bit(R5_Expanded, &dev->flags))
3330 			/* If we've reshaped into here, we assume it is Insync.
3331 			 * We will shortly update recovery_offset to make
3332 			 * it official.
3333 			 */
3334 			set_bit(R5_Insync, &dev->flags);
3335 
3336 		if (rdev && test_bit(R5_WriteError, &dev->flags)) {
3337 			/* This flag does not apply to '.replacement'
3338 			 * only to .rdev, so make sure to check that*/
3339 			struct md_rdev *rdev2 = rcu_dereference(
3340 				conf->disks[i].rdev);
3341 			if (rdev2 == rdev)
3342 				clear_bit(R5_Insync, &dev->flags);
3343 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3344 				s->handle_bad_blocks = 1;
3345 				atomic_inc(&rdev2->nr_pending);
3346 			} else
3347 				clear_bit(R5_WriteError, &dev->flags);
3348 		}
3349 		if (rdev && test_bit(R5_MadeGood, &dev->flags)) {
3350 			/* This flag does not apply to '.replacement'
3351 			 * only to .rdev, so make sure to check that*/
3352 			struct md_rdev *rdev2 = rcu_dereference(
3353 				conf->disks[i].rdev);
3354 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3355 				s->handle_bad_blocks = 1;
3356 				atomic_inc(&rdev2->nr_pending);
3357 			} else
3358 				clear_bit(R5_MadeGood, &dev->flags);
3359 		}
3360 		if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3361 			struct md_rdev *rdev2 = rcu_dereference(
3362 				conf->disks[i].replacement);
3363 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3364 				s->handle_bad_blocks = 1;
3365 				atomic_inc(&rdev2->nr_pending);
3366 			} else
3367 				clear_bit(R5_MadeGoodRepl, &dev->flags);
3368 		}
3369 		if (!test_bit(R5_Insync, &dev->flags)) {
3370 			/* The ReadError flag will just be confusing now */
3371 			clear_bit(R5_ReadError, &dev->flags);
3372 			clear_bit(R5_ReWrite, &dev->flags);
3373 		}
3374 		if (test_bit(R5_ReadError, &dev->flags))
3375 			clear_bit(R5_Insync, &dev->flags);
3376 		if (!test_bit(R5_Insync, &dev->flags)) {
3377 			if (s->failed < 2)
3378 				s->failed_num[s->failed] = i;
3379 			s->failed++;
3380 			if (rdev && !test_bit(Faulty, &rdev->flags))
3381 				do_recovery = 1;
3382 		}
3383 	}
3384 	if (test_bit(STRIPE_SYNCING, &sh->state)) {
3385 		/* If there is a failed device being replaced,
3386 		 *     we must be recovering.
3387 		 * else if we are after recovery_cp, we must be syncing
3388 		 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3389 		 * else we can only be replacing
3390 		 * sync and recovery both need to read all devices, and so
3391 		 * use the same flag.
3392 		 */
3393 		if (do_recovery ||
3394 		    sh->sector >= conf->mddev->recovery_cp ||
3395 		    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3396 			s->syncing = 1;
3397 		else
3398 			s->replacing = 1;
3399 	}
3400 	rcu_read_unlock();
3401 }
3402 
3403 static void handle_stripe(struct stripe_head *sh)
3404 {
3405 	struct stripe_head_state s;
3406 	struct r5conf *conf = sh->raid_conf;
3407 	int i;
3408 	int prexor;
3409 	int disks = sh->disks;
3410 	struct r5dev *pdev, *qdev;
3411 
3412 	clear_bit(STRIPE_HANDLE, &sh->state);
3413 	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3414 		/* already being handled, ensure it gets handled
3415 		 * again when current action finishes */
3416 		set_bit(STRIPE_HANDLE, &sh->state);
3417 		return;
3418 	}
3419 
3420 	if (test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3421 		set_bit(STRIPE_SYNCING, &sh->state);
3422 		clear_bit(STRIPE_INSYNC, &sh->state);
3423 	}
3424 	clear_bit(STRIPE_DELAYED, &sh->state);
3425 
3426 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3427 		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3428 	       (unsigned long long)sh->sector, sh->state,
3429 	       atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3430 	       sh->check_state, sh->reconstruct_state);
3431 
3432 	analyse_stripe(sh, &s);
3433 
3434 	if (s.handle_bad_blocks) {
3435 		set_bit(STRIPE_HANDLE, &sh->state);
3436 		goto finish;
3437 	}
3438 
3439 	if (unlikely(s.blocked_rdev)) {
3440 		if (s.syncing || s.expanding || s.expanded ||
3441 		    s.replacing || s.to_write || s.written) {
3442 			set_bit(STRIPE_HANDLE, &sh->state);
3443 			goto finish;
3444 		}
3445 		/* There is nothing for the blocked_rdev to block */
3446 		rdev_dec_pending(s.blocked_rdev, conf->mddev);
3447 		s.blocked_rdev = NULL;
3448 	}
3449 
3450 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3451 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3452 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3453 	}
3454 
3455 	pr_debug("locked=%d uptodate=%d to_read=%d"
3456 	       " to_write=%d failed=%d failed_num=%d,%d\n",
3457 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3458 	       s.failed_num[0], s.failed_num[1]);
3459 	/* check if the array has lost more than max_degraded devices and,
3460 	 * if so, some requests might need to be failed.
3461 	 */
3462 	if (s.failed > conf->max_degraded) {
3463 		sh->check_state = 0;
3464 		sh->reconstruct_state = 0;
3465 		if (s.to_read+s.to_write+s.written)
3466 			handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3467 		if (s.syncing + s.replacing)
3468 			handle_failed_sync(conf, sh, &s);
3469 	}
3470 
3471 	/* Now we check to see if any write operations have recently
3472 	 * completed
3473 	 */
3474 	prexor = 0;
3475 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3476 		prexor = 1;
3477 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
3478 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3479 		sh->reconstruct_state = reconstruct_state_idle;
3480 
3481 		/* All the 'written' buffers and the parity block are ready to
3482 		 * be written back to disk
3483 		 */
3484 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3485 		       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3486 		BUG_ON(sh->qd_idx >= 0 &&
3487 		       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3488 		       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3489 		for (i = disks; i--; ) {
3490 			struct r5dev *dev = &sh->dev[i];
3491 			if (test_bit(R5_LOCKED, &dev->flags) &&
3492 				(i == sh->pd_idx || i == sh->qd_idx ||
3493 				 dev->written)) {
3494 				pr_debug("Writing block %d\n", i);
3495 				set_bit(R5_Wantwrite, &dev->flags);
3496 				if (prexor)
3497 					continue;
3498 				if (!test_bit(R5_Insync, &dev->flags) ||
3499 				    ((i == sh->pd_idx || i == sh->qd_idx)  &&
3500 				     s.failed == 0))
3501 					set_bit(STRIPE_INSYNC, &sh->state);
3502 			}
3503 		}
3504 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3505 			s.dec_preread_active = 1;
3506 	}
3507 
3508 	/*
3509 	 * might be able to return some write requests if the parity blocks
3510 	 * are safe, or on a failed drive
3511 	 */
3512 	pdev = &sh->dev[sh->pd_idx];
3513 	s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3514 		|| (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3515 	qdev = &sh->dev[sh->qd_idx];
3516 	s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3517 		|| (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3518 		|| conf->level < 6;
3519 
3520 	if (s.written &&
3521 	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3522 			     && !test_bit(R5_LOCKED, &pdev->flags)
3523 			     && (test_bit(R5_UPTODATE, &pdev->flags) ||
3524 				 test_bit(R5_Discard, &pdev->flags))))) &&
3525 	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3526 			     && !test_bit(R5_LOCKED, &qdev->flags)
3527 			     && (test_bit(R5_UPTODATE, &qdev->flags) ||
3528 				 test_bit(R5_Discard, &qdev->flags))))))
3529 		handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3530 
3531 	/* Now we might consider reading some blocks, either to check/generate
3532 	 * parity, or to satisfy requests
3533 	 * or to load a block that is being partially written.
3534 	 */
3535 	if (s.to_read || s.non_overwrite
3536 	    || (conf->level == 6 && s.to_write && s.failed)
3537 	    || (s.syncing && (s.uptodate + s.compute < disks))
3538 	    || s.replacing
3539 	    || s.expanding)
3540 		handle_stripe_fill(sh, &s, disks);
3541 
3542 	/* Now to consider new write requests and what else, if anything
3543 	 * should be read.  We do not handle new writes when:
3544 	 * 1/ A 'write' operation (copy+xor) is already in flight.
3545 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
3546 	 *    block.
3547 	 */
3548 	if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3549 		handle_stripe_dirtying(conf, sh, &s, disks);
3550 
3551 	/* maybe we need to check and possibly fix the parity for this stripe
3552 	 * Any reads will already have been scheduled, so we just see if enough
3553 	 * data is available.  The parity check is held off while parity
3554 	 * dependent operations are in flight.
3555 	 */
3556 	if (sh->check_state ||
3557 	    (s.syncing && s.locked == 0 &&
3558 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3559 	     !test_bit(STRIPE_INSYNC, &sh->state))) {
3560 		if (conf->level == 6)
3561 			handle_parity_checks6(conf, sh, &s, disks);
3562 		else
3563 			handle_parity_checks5(conf, sh, &s, disks);
3564 	}
3565 
3566 	if (s.replacing && s.locked == 0
3567 	    && !test_bit(STRIPE_INSYNC, &sh->state)) {
3568 		/* Write out to replacement devices where possible */
3569 		for (i = 0; i < conf->raid_disks; i++)
3570 			if (test_bit(R5_UPTODATE, &sh->dev[i].flags) &&
3571 			    test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3572 				set_bit(R5_WantReplace, &sh->dev[i].flags);
3573 				set_bit(R5_LOCKED, &sh->dev[i].flags);
3574 				s.locked++;
3575 			}
3576 		set_bit(STRIPE_INSYNC, &sh->state);
3577 	}
3578 	if ((s.syncing || s.replacing) && s.locked == 0 &&
3579 	    test_bit(STRIPE_INSYNC, &sh->state)) {
3580 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3581 		clear_bit(STRIPE_SYNCING, &sh->state);
3582 	}
3583 
3584 	/* If the failed drives are just a ReadError, then we might need
3585 	 * to progress the repair/check process
3586 	 */
3587 	if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3588 		for (i = 0; i < s.failed; i++) {
3589 			struct r5dev *dev = &sh->dev[s.failed_num[i]];
3590 			if (test_bit(R5_ReadError, &dev->flags)
3591 			    && !test_bit(R5_LOCKED, &dev->flags)
3592 			    && test_bit(R5_UPTODATE, &dev->flags)
3593 				) {
3594 				if (!test_bit(R5_ReWrite, &dev->flags)) {
3595 					set_bit(R5_Wantwrite, &dev->flags);
3596 					set_bit(R5_ReWrite, &dev->flags);
3597 					set_bit(R5_LOCKED, &dev->flags);
3598 					s.locked++;
3599 				} else {
3600 					/* let's read it back */
3601 					set_bit(R5_Wantread, &dev->flags);
3602 					set_bit(R5_LOCKED, &dev->flags);
3603 					s.locked++;
3604 				}
3605 			}
3606 		}
3607 
3608 
3609 	/* Finish reconstruct operations initiated by the expansion process */
3610 	if (sh->reconstruct_state == reconstruct_state_result) {
3611 		struct stripe_head *sh_src
3612 			= get_active_stripe(conf, sh->sector, 1, 1, 1);
3613 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3614 			/* sh cannot be written until sh_src has been read.
3615 			 * so arrange for sh to be delayed a little
3616 			 */
3617 			set_bit(STRIPE_DELAYED, &sh->state);
3618 			set_bit(STRIPE_HANDLE, &sh->state);
3619 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3620 					      &sh_src->state))
3621 				atomic_inc(&conf->preread_active_stripes);
3622 			release_stripe(sh_src);
3623 			goto finish;
3624 		}
3625 		if (sh_src)
3626 			release_stripe(sh_src);
3627 
3628 		sh->reconstruct_state = reconstruct_state_idle;
3629 		clear_bit(STRIPE_EXPANDING, &sh->state);
3630 		for (i = conf->raid_disks; i--; ) {
3631 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
3632 			set_bit(R5_LOCKED, &sh->dev[i].flags);
3633 			s.locked++;
3634 		}
3635 	}
3636 
3637 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3638 	    !sh->reconstruct_state) {
3639 		/* Need to write out all blocks after computing parity */
3640 		sh->disks = conf->raid_disks;
3641 		stripe_set_idx(sh->sector, conf, 0, sh);
3642 		schedule_reconstruction(sh, &s, 1, 1);
3643 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3644 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
3645 		atomic_dec(&conf->reshape_stripes);
3646 		wake_up(&conf->wait_for_overlap);
3647 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3648 	}
3649 
3650 	if (s.expanding && s.locked == 0 &&
3651 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3652 		handle_stripe_expansion(conf, sh);
3653 
3654 finish:
3655 	/* wait for this device to become unblocked */
3656 	if (unlikely(s.blocked_rdev)) {
3657 		if (conf->mddev->external)
3658 			md_wait_for_blocked_rdev(s.blocked_rdev,
3659 						 conf->mddev);
3660 		else
3661 			/* Internal metadata will immediately
3662 			 * be written by raid5d, so we don't
3663 			 * need to wait here.
3664 			 */
3665 			rdev_dec_pending(s.blocked_rdev,
3666 					 conf->mddev);
3667 	}
3668 
3669 	if (s.handle_bad_blocks)
3670 		for (i = disks; i--; ) {
3671 			struct md_rdev *rdev;
3672 			struct r5dev *dev = &sh->dev[i];
3673 			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3674 				/* We own a safe reference to the rdev */
3675 				rdev = conf->disks[i].rdev;
3676 				if (!rdev_set_badblocks(rdev, sh->sector,
3677 							STRIPE_SECTORS, 0))
3678 					md_error(conf->mddev, rdev);
3679 				rdev_dec_pending(rdev, conf->mddev);
3680 			}
3681 			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3682 				rdev = conf->disks[i].rdev;
3683 				rdev_clear_badblocks(rdev, sh->sector,
3684 						     STRIPE_SECTORS, 0);
3685 				rdev_dec_pending(rdev, conf->mddev);
3686 			}
3687 			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
3688 				rdev = conf->disks[i].replacement;
3689 				if (!rdev)
3690 					/* rdev have been moved down */
3691 					rdev = conf->disks[i].rdev;
3692 				rdev_clear_badblocks(rdev, sh->sector,
3693 						     STRIPE_SECTORS, 0);
3694 				rdev_dec_pending(rdev, conf->mddev);
3695 			}
3696 		}
3697 
3698 	if (s.ops_request)
3699 		raid_run_ops(sh, s.ops_request);
3700 
3701 	ops_run_io(sh, &s);
3702 
3703 	if (s.dec_preread_active) {
3704 		/* We delay this until after ops_run_io so that if make_request
3705 		 * is waiting on a flush, it won't continue until the writes
3706 		 * have actually been submitted.
3707 		 */
3708 		atomic_dec(&conf->preread_active_stripes);
3709 		if (atomic_read(&conf->preread_active_stripes) <
3710 		    IO_THRESHOLD)
3711 			md_wakeup_thread(conf->mddev->thread);
3712 	}
3713 
3714 	return_io(s.return_bi);
3715 
3716 	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
3717 }
3718 
3719 static void raid5_activate_delayed(struct r5conf *conf)
3720 {
3721 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3722 		while (!list_empty(&conf->delayed_list)) {
3723 			struct list_head *l = conf->delayed_list.next;
3724 			struct stripe_head *sh;
3725 			sh = list_entry(l, struct stripe_head, lru);
3726 			list_del_init(l);
3727 			clear_bit(STRIPE_DELAYED, &sh->state);
3728 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3729 				atomic_inc(&conf->preread_active_stripes);
3730 			list_add_tail(&sh->lru, &conf->hold_list);
3731 		}
3732 	}
3733 }
3734 
3735 static void activate_bit_delay(struct r5conf *conf)
3736 {
3737 	/* device_lock is held */
3738 	struct list_head head;
3739 	list_add(&head, &conf->bitmap_list);
3740 	list_del_init(&conf->bitmap_list);
3741 	while (!list_empty(&head)) {
3742 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3743 		list_del_init(&sh->lru);
3744 		atomic_inc(&sh->count);
3745 		__release_stripe(conf, sh);
3746 	}
3747 }
3748 
3749 int md_raid5_congested(struct mddev *mddev, int bits)
3750 {
3751 	struct r5conf *conf = mddev->private;
3752 
3753 	/* No difference between reads and writes.  Just check
3754 	 * how busy the stripe_cache is
3755 	 */
3756 
3757 	if (conf->inactive_blocked)
3758 		return 1;
3759 	if (conf->quiesce)
3760 		return 1;
3761 	if (list_empty_careful(&conf->inactive_list))
3762 		return 1;
3763 
3764 	return 0;
3765 }
3766 EXPORT_SYMBOL_GPL(md_raid5_congested);
3767 
3768 static int raid5_congested(void *data, int bits)
3769 {
3770 	struct mddev *mddev = data;
3771 
3772 	return mddev_congested(mddev, bits) ||
3773 		md_raid5_congested(mddev, bits);
3774 }
3775 
3776 /* We want read requests to align with chunks where possible,
3777  * but write requests don't need to.
3778  */
3779 static int raid5_mergeable_bvec(struct request_queue *q,
3780 				struct bvec_merge_data *bvm,
3781 				struct bio_vec *biovec)
3782 {
3783 	struct mddev *mddev = q->queuedata;
3784 	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3785 	int max;
3786 	unsigned int chunk_sectors = mddev->chunk_sectors;
3787 	unsigned int bio_sectors = bvm->bi_size >> 9;
3788 
3789 	if ((bvm->bi_rw & 1) == WRITE)
3790 		return biovec->bv_len; /* always allow writes to be mergeable */
3791 
3792 	if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3793 		chunk_sectors = mddev->new_chunk_sectors;
3794 	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3795 	if (max < 0) max = 0;
3796 	if (max <= biovec->bv_len && bio_sectors == 0)
3797 		return biovec->bv_len;
3798 	else
3799 		return max;
3800 }
3801 
3802 
3803 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
3804 {
3805 	sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3806 	unsigned int chunk_sectors = mddev->chunk_sectors;
3807 	unsigned int bio_sectors = bio->bi_size >> 9;
3808 
3809 	if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3810 		chunk_sectors = mddev->new_chunk_sectors;
3811 	return  chunk_sectors >=
3812 		((sector & (chunk_sectors - 1)) + bio_sectors);
3813 }
3814 
3815 /*
3816  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3817  *  later sampled by raid5d.
3818  */
3819 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
3820 {
3821 	unsigned long flags;
3822 
3823 	spin_lock_irqsave(&conf->device_lock, flags);
3824 
3825 	bi->bi_next = conf->retry_read_aligned_list;
3826 	conf->retry_read_aligned_list = bi;
3827 
3828 	spin_unlock_irqrestore(&conf->device_lock, flags);
3829 	md_wakeup_thread(conf->mddev->thread);
3830 }
3831 
3832 
3833 static struct bio *remove_bio_from_retry(struct r5conf *conf)
3834 {
3835 	struct bio *bi;
3836 
3837 	bi = conf->retry_read_aligned;
3838 	if (bi) {
3839 		conf->retry_read_aligned = NULL;
3840 		return bi;
3841 	}
3842 	bi = conf->retry_read_aligned_list;
3843 	if(bi) {
3844 		conf->retry_read_aligned_list = bi->bi_next;
3845 		bi->bi_next = NULL;
3846 		/*
3847 		 * this sets the active strip count to 1 and the processed
3848 		 * strip count to zero (upper 8 bits)
3849 		 */
3850 		raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
3851 	}
3852 
3853 	return bi;
3854 }
3855 
3856 
3857 /*
3858  *  The "raid5_align_endio" should check if the read succeeded and if it
3859  *  did, call bio_endio on the original bio (having bio_put the new bio
3860  *  first).
3861  *  If the read failed..
3862  */
3863 static void raid5_align_endio(struct bio *bi, int error)
3864 {
3865 	struct bio* raid_bi  = bi->bi_private;
3866 	struct mddev *mddev;
3867 	struct r5conf *conf;
3868 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3869 	struct md_rdev *rdev;
3870 
3871 	bio_put(bi);
3872 
3873 	rdev = (void*)raid_bi->bi_next;
3874 	raid_bi->bi_next = NULL;
3875 	mddev = rdev->mddev;
3876 	conf = mddev->private;
3877 
3878 	rdev_dec_pending(rdev, conf->mddev);
3879 
3880 	if (!error && uptodate) {
3881 		bio_endio(raid_bi, 0);
3882 		if (atomic_dec_and_test(&conf->active_aligned_reads))
3883 			wake_up(&conf->wait_for_stripe);
3884 		return;
3885 	}
3886 
3887 
3888 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3889 
3890 	add_bio_to_retry(raid_bi, conf);
3891 }
3892 
3893 static int bio_fits_rdev(struct bio *bi)
3894 {
3895 	struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3896 
3897 	if ((bi->bi_size>>9) > queue_max_sectors(q))
3898 		return 0;
3899 	blk_recount_segments(q, bi);
3900 	if (bi->bi_phys_segments > queue_max_segments(q))
3901 		return 0;
3902 
3903 	if (q->merge_bvec_fn)
3904 		/* it's too hard to apply the merge_bvec_fn at this stage,
3905 		 * just just give up
3906 		 */
3907 		return 0;
3908 
3909 	return 1;
3910 }
3911 
3912 
3913 static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
3914 {
3915 	struct r5conf *conf = mddev->private;
3916 	int dd_idx;
3917 	struct bio* align_bi;
3918 	struct md_rdev *rdev;
3919 	sector_t end_sector;
3920 
3921 	if (!in_chunk_boundary(mddev, raid_bio)) {
3922 		pr_debug("chunk_aligned_read : non aligned\n");
3923 		return 0;
3924 	}
3925 	/*
3926 	 * use bio_clone_mddev to make a copy of the bio
3927 	 */
3928 	align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
3929 	if (!align_bi)
3930 		return 0;
3931 	/*
3932 	 *   set bi_end_io to a new function, and set bi_private to the
3933 	 *     original bio.
3934 	 */
3935 	align_bi->bi_end_io  = raid5_align_endio;
3936 	align_bi->bi_private = raid_bio;
3937 	/*
3938 	 *	compute position
3939 	 */
3940 	align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
3941 						    0,
3942 						    &dd_idx, NULL);
3943 
3944 	end_sector = align_bi->bi_sector + (align_bi->bi_size >> 9);
3945 	rcu_read_lock();
3946 	rdev = rcu_dereference(conf->disks[dd_idx].replacement);
3947 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
3948 	    rdev->recovery_offset < end_sector) {
3949 		rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3950 		if (rdev &&
3951 		    (test_bit(Faulty, &rdev->flags) ||
3952 		    !(test_bit(In_sync, &rdev->flags) ||
3953 		      rdev->recovery_offset >= end_sector)))
3954 			rdev = NULL;
3955 	}
3956 	if (rdev) {
3957 		sector_t first_bad;
3958 		int bad_sectors;
3959 
3960 		atomic_inc(&rdev->nr_pending);
3961 		rcu_read_unlock();
3962 		raid_bio->bi_next = (void*)rdev;
3963 		align_bi->bi_bdev =  rdev->bdev;
3964 		align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
3965 
3966 		if (!bio_fits_rdev(align_bi) ||
3967 		    is_badblock(rdev, align_bi->bi_sector, align_bi->bi_size>>9,
3968 				&first_bad, &bad_sectors)) {
3969 			/* too big in some way, or has a known bad block */
3970 			bio_put(align_bi);
3971 			rdev_dec_pending(rdev, mddev);
3972 			return 0;
3973 		}
3974 
3975 		/* No reshape active, so we can trust rdev->data_offset */
3976 		align_bi->bi_sector += rdev->data_offset;
3977 
3978 		spin_lock_irq(&conf->device_lock);
3979 		wait_event_lock_irq(conf->wait_for_stripe,
3980 				    conf->quiesce == 0,
3981 				    conf->device_lock);
3982 		atomic_inc(&conf->active_aligned_reads);
3983 		spin_unlock_irq(&conf->device_lock);
3984 
3985 		trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
3986 				      align_bi, disk_devt(mddev->gendisk),
3987 				      raid_bio->bi_sector);
3988 		generic_make_request(align_bi);
3989 		return 1;
3990 	} else {
3991 		rcu_read_unlock();
3992 		bio_put(align_bi);
3993 		return 0;
3994 	}
3995 }
3996 
3997 /* __get_priority_stripe - get the next stripe to process
3998  *
3999  * Full stripe writes are allowed to pass preread active stripes up until
4000  * the bypass_threshold is exceeded.  In general the bypass_count
4001  * increments when the handle_list is handled before the hold_list; however, it
4002  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4003  * stripe with in flight i/o.  The bypass_count will be reset when the
4004  * head of the hold_list has changed, i.e. the head was promoted to the
4005  * handle_list.
4006  */
4007 static struct stripe_head *__get_priority_stripe(struct r5conf *conf)
4008 {
4009 	struct stripe_head *sh;
4010 
4011 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4012 		  __func__,
4013 		  list_empty(&conf->handle_list) ? "empty" : "busy",
4014 		  list_empty(&conf->hold_list) ? "empty" : "busy",
4015 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
4016 
4017 	if (!list_empty(&conf->handle_list)) {
4018 		sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
4019 
4020 		if (list_empty(&conf->hold_list))
4021 			conf->bypass_count = 0;
4022 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4023 			if (conf->hold_list.next == conf->last_hold)
4024 				conf->bypass_count++;
4025 			else {
4026 				conf->last_hold = conf->hold_list.next;
4027 				conf->bypass_count -= conf->bypass_threshold;
4028 				if (conf->bypass_count < 0)
4029 					conf->bypass_count = 0;
4030 			}
4031 		}
4032 	} else if (!list_empty(&conf->hold_list) &&
4033 		   ((conf->bypass_threshold &&
4034 		     conf->bypass_count > conf->bypass_threshold) ||
4035 		    atomic_read(&conf->pending_full_writes) == 0)) {
4036 		sh = list_entry(conf->hold_list.next,
4037 				typeof(*sh), lru);
4038 		conf->bypass_count -= conf->bypass_threshold;
4039 		if (conf->bypass_count < 0)
4040 			conf->bypass_count = 0;
4041 	} else
4042 		return NULL;
4043 
4044 	list_del_init(&sh->lru);
4045 	atomic_inc(&sh->count);
4046 	BUG_ON(atomic_read(&sh->count) != 1);
4047 	return sh;
4048 }
4049 
4050 struct raid5_plug_cb {
4051 	struct blk_plug_cb	cb;
4052 	struct list_head	list;
4053 };
4054 
4055 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4056 {
4057 	struct raid5_plug_cb *cb = container_of(
4058 		blk_cb, struct raid5_plug_cb, cb);
4059 	struct stripe_head *sh;
4060 	struct mddev *mddev = cb->cb.data;
4061 	struct r5conf *conf = mddev->private;
4062 	int cnt = 0;
4063 
4064 	if (cb->list.next && !list_empty(&cb->list)) {
4065 		spin_lock_irq(&conf->device_lock);
4066 		while (!list_empty(&cb->list)) {
4067 			sh = list_first_entry(&cb->list, struct stripe_head, lru);
4068 			list_del_init(&sh->lru);
4069 			/*
4070 			 * avoid race release_stripe_plug() sees
4071 			 * STRIPE_ON_UNPLUG_LIST clear but the stripe
4072 			 * is still in our list
4073 			 */
4074 			smp_mb__before_clear_bit();
4075 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4076 			__release_stripe(conf, sh);
4077 			cnt++;
4078 		}
4079 		spin_unlock_irq(&conf->device_lock);
4080 	}
4081 	trace_block_unplug(mddev->queue, cnt, !from_schedule);
4082 	kfree(cb);
4083 }
4084 
4085 static void release_stripe_plug(struct mddev *mddev,
4086 				struct stripe_head *sh)
4087 {
4088 	struct blk_plug_cb *blk_cb = blk_check_plugged(
4089 		raid5_unplug, mddev,
4090 		sizeof(struct raid5_plug_cb));
4091 	struct raid5_plug_cb *cb;
4092 
4093 	if (!blk_cb) {
4094 		release_stripe(sh);
4095 		return;
4096 	}
4097 
4098 	cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4099 
4100 	if (cb->list.next == NULL)
4101 		INIT_LIST_HEAD(&cb->list);
4102 
4103 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4104 		list_add_tail(&sh->lru, &cb->list);
4105 	else
4106 		release_stripe(sh);
4107 }
4108 
4109 static void make_discard_request(struct mddev *mddev, struct bio *bi)
4110 {
4111 	struct r5conf *conf = mddev->private;
4112 	sector_t logical_sector, last_sector;
4113 	struct stripe_head *sh;
4114 	int remaining;
4115 	int stripe_sectors;
4116 
4117 	if (mddev->reshape_position != MaxSector)
4118 		/* Skip discard while reshape is happening */
4119 		return;
4120 
4121 	logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4122 	last_sector = bi->bi_sector + (bi->bi_size>>9);
4123 
4124 	bi->bi_next = NULL;
4125 	bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4126 
4127 	stripe_sectors = conf->chunk_sectors *
4128 		(conf->raid_disks - conf->max_degraded);
4129 	logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4130 					       stripe_sectors);
4131 	sector_div(last_sector, stripe_sectors);
4132 
4133 	logical_sector *= conf->chunk_sectors;
4134 	last_sector *= conf->chunk_sectors;
4135 
4136 	for (; logical_sector < last_sector;
4137 	     logical_sector += STRIPE_SECTORS) {
4138 		DEFINE_WAIT(w);
4139 		int d;
4140 	again:
4141 		sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4142 		prepare_to_wait(&conf->wait_for_overlap, &w,
4143 				TASK_UNINTERRUPTIBLE);
4144 		spin_lock_irq(&sh->stripe_lock);
4145 		for (d = 0; d < conf->raid_disks; d++) {
4146 			if (d == sh->pd_idx || d == sh->qd_idx)
4147 				continue;
4148 			if (sh->dev[d].towrite || sh->dev[d].toread) {
4149 				set_bit(R5_Overlap, &sh->dev[d].flags);
4150 				spin_unlock_irq(&sh->stripe_lock);
4151 				release_stripe(sh);
4152 				schedule();
4153 				goto again;
4154 			}
4155 		}
4156 		finish_wait(&conf->wait_for_overlap, &w);
4157 		for (d = 0; d < conf->raid_disks; d++) {
4158 			if (d == sh->pd_idx || d == sh->qd_idx)
4159 				continue;
4160 			sh->dev[d].towrite = bi;
4161 			set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4162 			raid5_inc_bi_active_stripes(bi);
4163 		}
4164 		spin_unlock_irq(&sh->stripe_lock);
4165 		if (conf->mddev->bitmap) {
4166 			for (d = 0;
4167 			     d < conf->raid_disks - conf->max_degraded;
4168 			     d++)
4169 				bitmap_startwrite(mddev->bitmap,
4170 						  sh->sector,
4171 						  STRIPE_SECTORS,
4172 						  0);
4173 			sh->bm_seq = conf->seq_flush + 1;
4174 			set_bit(STRIPE_BIT_DELAY, &sh->state);
4175 		}
4176 
4177 		set_bit(STRIPE_HANDLE, &sh->state);
4178 		clear_bit(STRIPE_DELAYED, &sh->state);
4179 		if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4180 			atomic_inc(&conf->preread_active_stripes);
4181 		release_stripe_plug(mddev, sh);
4182 	}
4183 
4184 	remaining = raid5_dec_bi_active_stripes(bi);
4185 	if (remaining == 0) {
4186 		md_write_end(mddev);
4187 		bio_endio(bi, 0);
4188 	}
4189 }
4190 
4191 static void make_request(struct mddev *mddev, struct bio * bi)
4192 {
4193 	struct r5conf *conf = mddev->private;
4194 	int dd_idx;
4195 	sector_t new_sector;
4196 	sector_t logical_sector, last_sector;
4197 	struct stripe_head *sh;
4198 	const int rw = bio_data_dir(bi);
4199 	int remaining;
4200 
4201 	if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4202 		md_flush_request(mddev, bi);
4203 		return;
4204 	}
4205 
4206 	md_write_start(mddev, bi);
4207 
4208 	if (rw == READ &&
4209 	     mddev->reshape_position == MaxSector &&
4210 	     chunk_aligned_read(mddev,bi))
4211 		return;
4212 
4213 	if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4214 		make_discard_request(mddev, bi);
4215 		return;
4216 	}
4217 
4218 	logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4219 	last_sector = bi->bi_sector + (bi->bi_size>>9);
4220 	bi->bi_next = NULL;
4221 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
4222 
4223 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4224 		DEFINE_WAIT(w);
4225 		int previous;
4226 
4227 	retry:
4228 		previous = 0;
4229 		prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4230 		if (unlikely(conf->reshape_progress != MaxSector)) {
4231 			/* spinlock is needed as reshape_progress may be
4232 			 * 64bit on a 32bit platform, and so it might be
4233 			 * possible to see a half-updated value
4234 			 * Of course reshape_progress could change after
4235 			 * the lock is dropped, so once we get a reference
4236 			 * to the stripe that we think it is, we will have
4237 			 * to check again.
4238 			 */
4239 			spin_lock_irq(&conf->device_lock);
4240 			if (mddev->reshape_backwards
4241 			    ? logical_sector < conf->reshape_progress
4242 			    : logical_sector >= conf->reshape_progress) {
4243 				previous = 1;
4244 			} else {
4245 				if (mddev->reshape_backwards
4246 				    ? logical_sector < conf->reshape_safe
4247 				    : logical_sector >= conf->reshape_safe) {
4248 					spin_unlock_irq(&conf->device_lock);
4249 					schedule();
4250 					goto retry;
4251 				}
4252 			}
4253 			spin_unlock_irq(&conf->device_lock);
4254 		}
4255 
4256 		new_sector = raid5_compute_sector(conf, logical_sector,
4257 						  previous,
4258 						  &dd_idx, NULL);
4259 		pr_debug("raid456: make_request, sector %llu logical %llu\n",
4260 			(unsigned long long)new_sector,
4261 			(unsigned long long)logical_sector);
4262 
4263 		sh = get_active_stripe(conf, new_sector, previous,
4264 				       (bi->bi_rw&RWA_MASK), 0);
4265 		if (sh) {
4266 			if (unlikely(previous)) {
4267 				/* expansion might have moved on while waiting for a
4268 				 * stripe, so we must do the range check again.
4269 				 * Expansion could still move past after this
4270 				 * test, but as we are holding a reference to
4271 				 * 'sh', we know that if that happens,
4272 				 *  STRIPE_EXPANDING will get set and the expansion
4273 				 * won't proceed until we finish with the stripe.
4274 				 */
4275 				int must_retry = 0;
4276 				spin_lock_irq(&conf->device_lock);
4277 				if (mddev->reshape_backwards
4278 				    ? logical_sector >= conf->reshape_progress
4279 				    : logical_sector < conf->reshape_progress)
4280 					/* mismatch, need to try again */
4281 					must_retry = 1;
4282 				spin_unlock_irq(&conf->device_lock);
4283 				if (must_retry) {
4284 					release_stripe(sh);
4285 					schedule();
4286 					goto retry;
4287 				}
4288 			}
4289 
4290 			if (rw == WRITE &&
4291 			    logical_sector >= mddev->suspend_lo &&
4292 			    logical_sector < mddev->suspend_hi) {
4293 				release_stripe(sh);
4294 				/* As the suspend_* range is controlled by
4295 				 * userspace, we want an interruptible
4296 				 * wait.
4297 				 */
4298 				flush_signals(current);
4299 				prepare_to_wait(&conf->wait_for_overlap,
4300 						&w, TASK_INTERRUPTIBLE);
4301 				if (logical_sector >= mddev->suspend_lo &&
4302 				    logical_sector < mddev->suspend_hi)
4303 					schedule();
4304 				goto retry;
4305 			}
4306 
4307 			if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4308 			    !add_stripe_bio(sh, bi, dd_idx, rw)) {
4309 				/* Stripe is busy expanding or
4310 				 * add failed due to overlap.  Flush everything
4311 				 * and wait a while
4312 				 */
4313 				md_wakeup_thread(mddev->thread);
4314 				release_stripe(sh);
4315 				schedule();
4316 				goto retry;
4317 			}
4318 			finish_wait(&conf->wait_for_overlap, &w);
4319 			set_bit(STRIPE_HANDLE, &sh->state);
4320 			clear_bit(STRIPE_DELAYED, &sh->state);
4321 			if ((bi->bi_rw & REQ_SYNC) &&
4322 			    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4323 				atomic_inc(&conf->preread_active_stripes);
4324 			release_stripe_plug(mddev, sh);
4325 		} else {
4326 			/* cannot get stripe for read-ahead, just give-up */
4327 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
4328 			finish_wait(&conf->wait_for_overlap, &w);
4329 			break;
4330 		}
4331 	}
4332 
4333 	remaining = raid5_dec_bi_active_stripes(bi);
4334 	if (remaining == 0) {
4335 
4336 		if ( rw == WRITE )
4337 			md_write_end(mddev);
4338 
4339 		bio_endio(bi, 0);
4340 	}
4341 }
4342 
4343 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4344 
4345 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4346 {
4347 	/* reshaping is quite different to recovery/resync so it is
4348 	 * handled quite separately ... here.
4349 	 *
4350 	 * On each call to sync_request, we gather one chunk worth of
4351 	 * destination stripes and flag them as expanding.
4352 	 * Then we find all the source stripes and request reads.
4353 	 * As the reads complete, handle_stripe will copy the data
4354 	 * into the destination stripe and release that stripe.
4355 	 */
4356 	struct r5conf *conf = mddev->private;
4357 	struct stripe_head *sh;
4358 	sector_t first_sector, last_sector;
4359 	int raid_disks = conf->previous_raid_disks;
4360 	int data_disks = raid_disks - conf->max_degraded;
4361 	int new_data_disks = conf->raid_disks - conf->max_degraded;
4362 	int i;
4363 	int dd_idx;
4364 	sector_t writepos, readpos, safepos;
4365 	sector_t stripe_addr;
4366 	int reshape_sectors;
4367 	struct list_head stripes;
4368 
4369 	if (sector_nr == 0) {
4370 		/* If restarting in the middle, skip the initial sectors */
4371 		if (mddev->reshape_backwards &&
4372 		    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4373 			sector_nr = raid5_size(mddev, 0, 0)
4374 				- conf->reshape_progress;
4375 		} else if (!mddev->reshape_backwards &&
4376 			   conf->reshape_progress > 0)
4377 			sector_nr = conf->reshape_progress;
4378 		sector_div(sector_nr, new_data_disks);
4379 		if (sector_nr) {
4380 			mddev->curr_resync_completed = sector_nr;
4381 			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4382 			*skipped = 1;
4383 			return sector_nr;
4384 		}
4385 	}
4386 
4387 	/* We need to process a full chunk at a time.
4388 	 * If old and new chunk sizes differ, we need to process the
4389 	 * largest of these
4390 	 */
4391 	if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4392 		reshape_sectors = mddev->new_chunk_sectors;
4393 	else
4394 		reshape_sectors = mddev->chunk_sectors;
4395 
4396 	/* We update the metadata at least every 10 seconds, or when
4397 	 * the data about to be copied would over-write the source of
4398 	 * the data at the front of the range.  i.e. one new_stripe
4399 	 * along from reshape_progress new_maps to after where
4400 	 * reshape_safe old_maps to
4401 	 */
4402 	writepos = conf->reshape_progress;
4403 	sector_div(writepos, new_data_disks);
4404 	readpos = conf->reshape_progress;
4405 	sector_div(readpos, data_disks);
4406 	safepos = conf->reshape_safe;
4407 	sector_div(safepos, data_disks);
4408 	if (mddev->reshape_backwards) {
4409 		writepos -= min_t(sector_t, reshape_sectors, writepos);
4410 		readpos += reshape_sectors;
4411 		safepos += reshape_sectors;
4412 	} else {
4413 		writepos += reshape_sectors;
4414 		readpos -= min_t(sector_t, reshape_sectors, readpos);
4415 		safepos -= min_t(sector_t, reshape_sectors, safepos);
4416 	}
4417 
4418 	/* Having calculated the 'writepos' possibly use it
4419 	 * to set 'stripe_addr' which is where we will write to.
4420 	 */
4421 	if (mddev->reshape_backwards) {
4422 		BUG_ON(conf->reshape_progress == 0);
4423 		stripe_addr = writepos;
4424 		BUG_ON((mddev->dev_sectors &
4425 			~((sector_t)reshape_sectors - 1))
4426 		       - reshape_sectors - stripe_addr
4427 		       != sector_nr);
4428 	} else {
4429 		BUG_ON(writepos != sector_nr + reshape_sectors);
4430 		stripe_addr = sector_nr;
4431 	}
4432 
4433 	/* 'writepos' is the most advanced device address we might write.
4434 	 * 'readpos' is the least advanced device address we might read.
4435 	 * 'safepos' is the least address recorded in the metadata as having
4436 	 *     been reshaped.
4437 	 * If there is a min_offset_diff, these are adjusted either by
4438 	 * increasing the safepos/readpos if diff is negative, or
4439 	 * increasing writepos if diff is positive.
4440 	 * If 'readpos' is then behind 'writepos', there is no way that we can
4441 	 * ensure safety in the face of a crash - that must be done by userspace
4442 	 * making a backup of the data.  So in that case there is no particular
4443 	 * rush to update metadata.
4444 	 * Otherwise if 'safepos' is behind 'writepos', then we really need to
4445 	 * update the metadata to advance 'safepos' to match 'readpos' so that
4446 	 * we can be safe in the event of a crash.
4447 	 * So we insist on updating metadata if safepos is behind writepos and
4448 	 * readpos is beyond writepos.
4449 	 * In any case, update the metadata every 10 seconds.
4450 	 * Maybe that number should be configurable, but I'm not sure it is
4451 	 * worth it.... maybe it could be a multiple of safemode_delay???
4452 	 */
4453 	if (conf->min_offset_diff < 0) {
4454 		safepos += -conf->min_offset_diff;
4455 		readpos += -conf->min_offset_diff;
4456 	} else
4457 		writepos += conf->min_offset_diff;
4458 
4459 	if ((mddev->reshape_backwards
4460 	     ? (safepos > writepos && readpos < writepos)
4461 	     : (safepos < writepos && readpos > writepos)) ||
4462 	    time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4463 		/* Cannot proceed until we've updated the superblock... */
4464 		wait_event(conf->wait_for_overlap,
4465 			   atomic_read(&conf->reshape_stripes)==0);
4466 		mddev->reshape_position = conf->reshape_progress;
4467 		mddev->curr_resync_completed = sector_nr;
4468 		conf->reshape_checkpoint = jiffies;
4469 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
4470 		md_wakeup_thread(mddev->thread);
4471 		wait_event(mddev->sb_wait, mddev->flags == 0 ||
4472 			   kthread_should_stop());
4473 		spin_lock_irq(&conf->device_lock);
4474 		conf->reshape_safe = mddev->reshape_position;
4475 		spin_unlock_irq(&conf->device_lock);
4476 		wake_up(&conf->wait_for_overlap);
4477 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4478 	}
4479 
4480 	INIT_LIST_HEAD(&stripes);
4481 	for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4482 		int j;
4483 		int skipped_disk = 0;
4484 		sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4485 		set_bit(STRIPE_EXPANDING, &sh->state);
4486 		atomic_inc(&conf->reshape_stripes);
4487 		/* If any of this stripe is beyond the end of the old
4488 		 * array, then we need to zero those blocks
4489 		 */
4490 		for (j=sh->disks; j--;) {
4491 			sector_t s;
4492 			if (j == sh->pd_idx)
4493 				continue;
4494 			if (conf->level == 6 &&
4495 			    j == sh->qd_idx)
4496 				continue;
4497 			s = compute_blocknr(sh, j, 0);
4498 			if (s < raid5_size(mddev, 0, 0)) {
4499 				skipped_disk = 1;
4500 				continue;
4501 			}
4502 			memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4503 			set_bit(R5_Expanded, &sh->dev[j].flags);
4504 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
4505 		}
4506 		if (!skipped_disk) {
4507 			set_bit(STRIPE_EXPAND_READY, &sh->state);
4508 			set_bit(STRIPE_HANDLE, &sh->state);
4509 		}
4510 		list_add(&sh->lru, &stripes);
4511 	}
4512 	spin_lock_irq(&conf->device_lock);
4513 	if (mddev->reshape_backwards)
4514 		conf->reshape_progress -= reshape_sectors * new_data_disks;
4515 	else
4516 		conf->reshape_progress += reshape_sectors * new_data_disks;
4517 	spin_unlock_irq(&conf->device_lock);
4518 	/* Ok, those stripe are ready. We can start scheduling
4519 	 * reads on the source stripes.
4520 	 * The source stripes are determined by mapping the first and last
4521 	 * block on the destination stripes.
4522 	 */
4523 	first_sector =
4524 		raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4525 				     1, &dd_idx, NULL);
4526 	last_sector =
4527 		raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4528 					    * new_data_disks - 1),
4529 				     1, &dd_idx, NULL);
4530 	if (last_sector >= mddev->dev_sectors)
4531 		last_sector = mddev->dev_sectors - 1;
4532 	while (first_sector <= last_sector) {
4533 		sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4534 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4535 		set_bit(STRIPE_HANDLE, &sh->state);
4536 		release_stripe(sh);
4537 		first_sector += STRIPE_SECTORS;
4538 	}
4539 	/* Now that the sources are clearly marked, we can release
4540 	 * the destination stripes
4541 	 */
4542 	while (!list_empty(&stripes)) {
4543 		sh = list_entry(stripes.next, struct stripe_head, lru);
4544 		list_del_init(&sh->lru);
4545 		release_stripe(sh);
4546 	}
4547 	/* If this takes us to the resync_max point where we have to pause,
4548 	 * then we need to write out the superblock.
4549 	 */
4550 	sector_nr += reshape_sectors;
4551 	if ((sector_nr - mddev->curr_resync_completed) * 2
4552 	    >= mddev->resync_max - mddev->curr_resync_completed) {
4553 		/* Cannot proceed until we've updated the superblock... */
4554 		wait_event(conf->wait_for_overlap,
4555 			   atomic_read(&conf->reshape_stripes) == 0);
4556 		mddev->reshape_position = conf->reshape_progress;
4557 		mddev->curr_resync_completed = sector_nr;
4558 		conf->reshape_checkpoint = jiffies;
4559 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
4560 		md_wakeup_thread(mddev->thread);
4561 		wait_event(mddev->sb_wait,
4562 			   !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4563 			   || kthread_should_stop());
4564 		spin_lock_irq(&conf->device_lock);
4565 		conf->reshape_safe = mddev->reshape_position;
4566 		spin_unlock_irq(&conf->device_lock);
4567 		wake_up(&conf->wait_for_overlap);
4568 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4569 	}
4570 	return reshape_sectors;
4571 }
4572 
4573 /* FIXME go_faster isn't used */
4574 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4575 {
4576 	struct r5conf *conf = mddev->private;
4577 	struct stripe_head *sh;
4578 	sector_t max_sector = mddev->dev_sectors;
4579 	sector_t sync_blocks;
4580 	int still_degraded = 0;
4581 	int i;
4582 
4583 	if (sector_nr >= max_sector) {
4584 		/* just being told to finish up .. nothing much to do */
4585 
4586 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4587 			end_reshape(conf);
4588 			return 0;
4589 		}
4590 
4591 		if (mddev->curr_resync < max_sector) /* aborted */
4592 			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4593 					&sync_blocks, 1);
4594 		else /* completed sync */
4595 			conf->fullsync = 0;
4596 		bitmap_close_sync(mddev->bitmap);
4597 
4598 		return 0;
4599 	}
4600 
4601 	/* Allow raid5_quiesce to complete */
4602 	wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4603 
4604 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4605 		return reshape_request(mddev, sector_nr, skipped);
4606 
4607 	/* No need to check resync_max as we never do more than one
4608 	 * stripe, and as resync_max will always be on a chunk boundary,
4609 	 * if the check in md_do_sync didn't fire, there is no chance
4610 	 * of overstepping resync_max here
4611 	 */
4612 
4613 	/* if there is too many failed drives and we are trying
4614 	 * to resync, then assert that we are finished, because there is
4615 	 * nothing we can do.
4616 	 */
4617 	if (mddev->degraded >= conf->max_degraded &&
4618 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4619 		sector_t rv = mddev->dev_sectors - sector_nr;
4620 		*skipped = 1;
4621 		return rv;
4622 	}
4623 	if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4624 	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4625 	    !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
4626 		/* we can skip this block, and probably more */
4627 		sync_blocks /= STRIPE_SECTORS;
4628 		*skipped = 1;
4629 		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4630 	}
4631 
4632 	bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4633 
4634 	sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4635 	if (sh == NULL) {
4636 		sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4637 		/* make sure we don't swamp the stripe cache if someone else
4638 		 * is trying to get access
4639 		 */
4640 		schedule_timeout_uninterruptible(1);
4641 	}
4642 	/* Need to check if array will still be degraded after recovery/resync
4643 	 * We don't need to check the 'failed' flag as when that gets set,
4644 	 * recovery aborts.
4645 	 */
4646 	for (i = 0; i < conf->raid_disks; i++)
4647 		if (conf->disks[i].rdev == NULL)
4648 			still_degraded = 1;
4649 
4650 	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4651 
4652 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4653 
4654 	handle_stripe(sh);
4655 	release_stripe(sh);
4656 
4657 	return STRIPE_SECTORS;
4658 }
4659 
4660 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
4661 {
4662 	/* We may not be able to submit a whole bio at once as there
4663 	 * may not be enough stripe_heads available.
4664 	 * We cannot pre-allocate enough stripe_heads as we may need
4665 	 * more than exist in the cache (if we allow ever large chunks).
4666 	 * So we do one stripe head at a time and record in
4667 	 * ->bi_hw_segments how many have been done.
4668 	 *
4669 	 * We *know* that this entire raid_bio is in one chunk, so
4670 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4671 	 */
4672 	struct stripe_head *sh;
4673 	int dd_idx;
4674 	sector_t sector, logical_sector, last_sector;
4675 	int scnt = 0;
4676 	int remaining;
4677 	int handled = 0;
4678 
4679 	logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4680 	sector = raid5_compute_sector(conf, logical_sector,
4681 				      0, &dd_idx, NULL);
4682 	last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
4683 
4684 	for (; logical_sector < last_sector;
4685 	     logical_sector += STRIPE_SECTORS,
4686 		     sector += STRIPE_SECTORS,
4687 		     scnt++) {
4688 
4689 		if (scnt < raid5_bi_processed_stripes(raid_bio))
4690 			/* already done this stripe */
4691 			continue;
4692 
4693 		sh = get_active_stripe(conf, sector, 0, 1, 0);
4694 
4695 		if (!sh) {
4696 			/* failed to get a stripe - must wait */
4697 			raid5_set_bi_processed_stripes(raid_bio, scnt);
4698 			conf->retry_read_aligned = raid_bio;
4699 			return handled;
4700 		}
4701 
4702 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4703 			release_stripe(sh);
4704 			raid5_set_bi_processed_stripes(raid_bio, scnt);
4705 			conf->retry_read_aligned = raid_bio;
4706 			return handled;
4707 		}
4708 
4709 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
4710 		handle_stripe(sh);
4711 		release_stripe(sh);
4712 		handled++;
4713 	}
4714 	remaining = raid5_dec_bi_active_stripes(raid_bio);
4715 	if (remaining == 0)
4716 		bio_endio(raid_bio, 0);
4717 	if (atomic_dec_and_test(&conf->active_aligned_reads))
4718 		wake_up(&conf->wait_for_stripe);
4719 	return handled;
4720 }
4721 
4722 #define MAX_STRIPE_BATCH 8
4723 static int handle_active_stripes(struct r5conf *conf)
4724 {
4725 	struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
4726 	int i, batch_size = 0;
4727 
4728 	while (batch_size < MAX_STRIPE_BATCH &&
4729 			(sh = __get_priority_stripe(conf)) != NULL)
4730 		batch[batch_size++] = sh;
4731 
4732 	if (batch_size == 0)
4733 		return batch_size;
4734 	spin_unlock_irq(&conf->device_lock);
4735 
4736 	for (i = 0; i < batch_size; i++)
4737 		handle_stripe(batch[i]);
4738 
4739 	cond_resched();
4740 
4741 	spin_lock_irq(&conf->device_lock);
4742 	for (i = 0; i < batch_size; i++)
4743 		__release_stripe(conf, batch[i]);
4744 	return batch_size;
4745 }
4746 
4747 /*
4748  * This is our raid5 kernel thread.
4749  *
4750  * We scan the hash table for stripes which can be handled now.
4751  * During the scan, completed stripes are saved for us by the interrupt
4752  * handler, so that they will not have to wait for our next wakeup.
4753  */
4754 static void raid5d(struct md_thread *thread)
4755 {
4756 	struct mddev *mddev = thread->mddev;
4757 	struct r5conf *conf = mddev->private;
4758 	int handled;
4759 	struct blk_plug plug;
4760 
4761 	pr_debug("+++ raid5d active\n");
4762 
4763 	md_check_recovery(mddev);
4764 
4765 	blk_start_plug(&plug);
4766 	handled = 0;
4767 	spin_lock_irq(&conf->device_lock);
4768 	while (1) {
4769 		struct bio *bio;
4770 		int batch_size;
4771 
4772 		if (
4773 		    !list_empty(&conf->bitmap_list)) {
4774 			/* Now is a good time to flush some bitmap updates */
4775 			conf->seq_flush++;
4776 			spin_unlock_irq(&conf->device_lock);
4777 			bitmap_unplug(mddev->bitmap);
4778 			spin_lock_irq(&conf->device_lock);
4779 			conf->seq_write = conf->seq_flush;
4780 			activate_bit_delay(conf);
4781 		}
4782 		raid5_activate_delayed(conf);
4783 
4784 		while ((bio = remove_bio_from_retry(conf))) {
4785 			int ok;
4786 			spin_unlock_irq(&conf->device_lock);
4787 			ok = retry_aligned_read(conf, bio);
4788 			spin_lock_irq(&conf->device_lock);
4789 			if (!ok)
4790 				break;
4791 			handled++;
4792 		}
4793 
4794 		batch_size = handle_active_stripes(conf);
4795 		if (!batch_size)
4796 			break;
4797 		handled += batch_size;
4798 
4799 		if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
4800 			spin_unlock_irq(&conf->device_lock);
4801 			md_check_recovery(mddev);
4802 			spin_lock_irq(&conf->device_lock);
4803 		}
4804 	}
4805 	pr_debug("%d stripes handled\n", handled);
4806 
4807 	spin_unlock_irq(&conf->device_lock);
4808 
4809 	async_tx_issue_pending_all();
4810 	blk_finish_plug(&plug);
4811 
4812 	pr_debug("--- raid5d inactive\n");
4813 }
4814 
4815 static ssize_t
4816 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
4817 {
4818 	struct r5conf *conf = mddev->private;
4819 	if (conf)
4820 		return sprintf(page, "%d\n", conf->max_nr_stripes);
4821 	else
4822 		return 0;
4823 }
4824 
4825 int
4826 raid5_set_cache_size(struct mddev *mddev, int size)
4827 {
4828 	struct r5conf *conf = mddev->private;
4829 	int err;
4830 
4831 	if (size <= 16 || size > 32768)
4832 		return -EINVAL;
4833 	while (size < conf->max_nr_stripes) {
4834 		if (drop_one_stripe(conf))
4835 			conf->max_nr_stripes--;
4836 		else
4837 			break;
4838 	}
4839 	err = md_allow_write(mddev);
4840 	if (err)
4841 		return err;
4842 	while (size > conf->max_nr_stripes) {
4843 		if (grow_one_stripe(conf))
4844 			conf->max_nr_stripes++;
4845 		else break;
4846 	}
4847 	return 0;
4848 }
4849 EXPORT_SYMBOL(raid5_set_cache_size);
4850 
4851 static ssize_t
4852 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
4853 {
4854 	struct r5conf *conf = mddev->private;
4855 	unsigned long new;
4856 	int err;
4857 
4858 	if (len >= PAGE_SIZE)
4859 		return -EINVAL;
4860 	if (!conf)
4861 		return -ENODEV;
4862 
4863 	if (strict_strtoul(page, 10, &new))
4864 		return -EINVAL;
4865 	err = raid5_set_cache_size(mddev, new);
4866 	if (err)
4867 		return err;
4868 	return len;
4869 }
4870 
4871 static struct md_sysfs_entry
4872 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4873 				raid5_show_stripe_cache_size,
4874 				raid5_store_stripe_cache_size);
4875 
4876 static ssize_t
4877 raid5_show_preread_threshold(struct mddev *mddev, char *page)
4878 {
4879 	struct r5conf *conf = mddev->private;
4880 	if (conf)
4881 		return sprintf(page, "%d\n", conf->bypass_threshold);
4882 	else
4883 		return 0;
4884 }
4885 
4886 static ssize_t
4887 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
4888 {
4889 	struct r5conf *conf = mddev->private;
4890 	unsigned long new;
4891 	if (len >= PAGE_SIZE)
4892 		return -EINVAL;
4893 	if (!conf)
4894 		return -ENODEV;
4895 
4896 	if (strict_strtoul(page, 10, &new))
4897 		return -EINVAL;
4898 	if (new > conf->max_nr_stripes)
4899 		return -EINVAL;
4900 	conf->bypass_threshold = new;
4901 	return len;
4902 }
4903 
4904 static struct md_sysfs_entry
4905 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
4906 					S_IRUGO | S_IWUSR,
4907 					raid5_show_preread_threshold,
4908 					raid5_store_preread_threshold);
4909 
4910 static ssize_t
4911 stripe_cache_active_show(struct mddev *mddev, char *page)
4912 {
4913 	struct r5conf *conf = mddev->private;
4914 	if (conf)
4915 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
4916 	else
4917 		return 0;
4918 }
4919 
4920 static struct md_sysfs_entry
4921 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
4922 
4923 static struct attribute *raid5_attrs[] =  {
4924 	&raid5_stripecache_size.attr,
4925 	&raid5_stripecache_active.attr,
4926 	&raid5_preread_bypass_threshold.attr,
4927 	NULL,
4928 };
4929 static struct attribute_group raid5_attrs_group = {
4930 	.name = NULL,
4931 	.attrs = raid5_attrs,
4932 };
4933 
4934 static sector_t
4935 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
4936 {
4937 	struct r5conf *conf = mddev->private;
4938 
4939 	if (!sectors)
4940 		sectors = mddev->dev_sectors;
4941 	if (!raid_disks)
4942 		/* size is defined by the smallest of previous and new size */
4943 		raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
4944 
4945 	sectors &= ~((sector_t)mddev->chunk_sectors - 1);
4946 	sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
4947 	return sectors * (raid_disks - conf->max_degraded);
4948 }
4949 
4950 static void raid5_free_percpu(struct r5conf *conf)
4951 {
4952 	struct raid5_percpu *percpu;
4953 	unsigned long cpu;
4954 
4955 	if (!conf->percpu)
4956 		return;
4957 
4958 	get_online_cpus();
4959 	for_each_possible_cpu(cpu) {
4960 		percpu = per_cpu_ptr(conf->percpu, cpu);
4961 		safe_put_page(percpu->spare_page);
4962 		kfree(percpu->scribble);
4963 	}
4964 #ifdef CONFIG_HOTPLUG_CPU
4965 	unregister_cpu_notifier(&conf->cpu_notify);
4966 #endif
4967 	put_online_cpus();
4968 
4969 	free_percpu(conf->percpu);
4970 }
4971 
4972 static void free_conf(struct r5conf *conf)
4973 {
4974 	shrink_stripes(conf);
4975 	raid5_free_percpu(conf);
4976 	kfree(conf->disks);
4977 	kfree(conf->stripe_hashtbl);
4978 	kfree(conf);
4979 }
4980 
4981 #ifdef CONFIG_HOTPLUG_CPU
4982 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
4983 			      void *hcpu)
4984 {
4985 	struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
4986 	long cpu = (long)hcpu;
4987 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
4988 
4989 	switch (action) {
4990 	case CPU_UP_PREPARE:
4991 	case CPU_UP_PREPARE_FROZEN:
4992 		if (conf->level == 6 && !percpu->spare_page)
4993 			percpu->spare_page = alloc_page(GFP_KERNEL);
4994 		if (!percpu->scribble)
4995 			percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
4996 
4997 		if (!percpu->scribble ||
4998 		    (conf->level == 6 && !percpu->spare_page)) {
4999 			safe_put_page(percpu->spare_page);
5000 			kfree(percpu->scribble);
5001 			pr_err("%s: failed memory allocation for cpu%ld\n",
5002 			       __func__, cpu);
5003 			return notifier_from_errno(-ENOMEM);
5004 		}
5005 		break;
5006 	case CPU_DEAD:
5007 	case CPU_DEAD_FROZEN:
5008 		safe_put_page(percpu->spare_page);
5009 		kfree(percpu->scribble);
5010 		percpu->spare_page = NULL;
5011 		percpu->scribble = NULL;
5012 		break;
5013 	default:
5014 		break;
5015 	}
5016 	return NOTIFY_OK;
5017 }
5018 #endif
5019 
5020 static int raid5_alloc_percpu(struct r5conf *conf)
5021 {
5022 	unsigned long cpu;
5023 	struct page *spare_page;
5024 	struct raid5_percpu __percpu *allcpus;
5025 	void *scribble;
5026 	int err;
5027 
5028 	allcpus = alloc_percpu(struct raid5_percpu);
5029 	if (!allcpus)
5030 		return -ENOMEM;
5031 	conf->percpu = allcpus;
5032 
5033 	get_online_cpus();
5034 	err = 0;
5035 	for_each_present_cpu(cpu) {
5036 		if (conf->level == 6) {
5037 			spare_page = alloc_page(GFP_KERNEL);
5038 			if (!spare_page) {
5039 				err = -ENOMEM;
5040 				break;
5041 			}
5042 			per_cpu_ptr(conf->percpu, cpu)->spare_page = spare_page;
5043 		}
5044 		scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5045 		if (!scribble) {
5046 			err = -ENOMEM;
5047 			break;
5048 		}
5049 		per_cpu_ptr(conf->percpu, cpu)->scribble = scribble;
5050 	}
5051 #ifdef CONFIG_HOTPLUG_CPU
5052 	conf->cpu_notify.notifier_call = raid456_cpu_notify;
5053 	conf->cpu_notify.priority = 0;
5054 	if (err == 0)
5055 		err = register_cpu_notifier(&conf->cpu_notify);
5056 #endif
5057 	put_online_cpus();
5058 
5059 	return err;
5060 }
5061 
5062 static struct r5conf *setup_conf(struct mddev *mddev)
5063 {
5064 	struct r5conf *conf;
5065 	int raid_disk, memory, max_disks;
5066 	struct md_rdev *rdev;
5067 	struct disk_info *disk;
5068 	char pers_name[6];
5069 
5070 	if (mddev->new_level != 5
5071 	    && mddev->new_level != 4
5072 	    && mddev->new_level != 6) {
5073 		printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
5074 		       mdname(mddev), mddev->new_level);
5075 		return ERR_PTR(-EIO);
5076 	}
5077 	if ((mddev->new_level == 5
5078 	     && !algorithm_valid_raid5(mddev->new_layout)) ||
5079 	    (mddev->new_level == 6
5080 	     && !algorithm_valid_raid6(mddev->new_layout))) {
5081 		printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
5082 		       mdname(mddev), mddev->new_layout);
5083 		return ERR_PTR(-EIO);
5084 	}
5085 	if (mddev->new_level == 6 && mddev->raid_disks < 4) {
5086 		printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
5087 		       mdname(mddev), mddev->raid_disks);
5088 		return ERR_PTR(-EINVAL);
5089 	}
5090 
5091 	if (!mddev->new_chunk_sectors ||
5092 	    (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
5093 	    !is_power_of_2(mddev->new_chunk_sectors)) {
5094 		printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
5095 		       mdname(mddev), mddev->new_chunk_sectors << 9);
5096 		return ERR_PTR(-EINVAL);
5097 	}
5098 
5099 	conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
5100 	if (conf == NULL)
5101 		goto abort;
5102 	spin_lock_init(&conf->device_lock);
5103 	init_waitqueue_head(&conf->wait_for_stripe);
5104 	init_waitqueue_head(&conf->wait_for_overlap);
5105 	INIT_LIST_HEAD(&conf->handle_list);
5106 	INIT_LIST_HEAD(&conf->hold_list);
5107 	INIT_LIST_HEAD(&conf->delayed_list);
5108 	INIT_LIST_HEAD(&conf->bitmap_list);
5109 	INIT_LIST_HEAD(&conf->inactive_list);
5110 	atomic_set(&conf->active_stripes, 0);
5111 	atomic_set(&conf->preread_active_stripes, 0);
5112 	atomic_set(&conf->active_aligned_reads, 0);
5113 	conf->bypass_threshold = BYPASS_THRESHOLD;
5114 	conf->recovery_disabled = mddev->recovery_disabled - 1;
5115 
5116 	conf->raid_disks = mddev->raid_disks;
5117 	if (mddev->reshape_position == MaxSector)
5118 		conf->previous_raid_disks = mddev->raid_disks;
5119 	else
5120 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
5121 	max_disks = max(conf->raid_disks, conf->previous_raid_disks);
5122 	conf->scribble_len = scribble_len(max_disks);
5123 
5124 	conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
5125 			      GFP_KERNEL);
5126 	if (!conf->disks)
5127 		goto abort;
5128 
5129 	conf->mddev = mddev;
5130 
5131 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
5132 		goto abort;
5133 
5134 	conf->level = mddev->new_level;
5135 	if (raid5_alloc_percpu(conf) != 0)
5136 		goto abort;
5137 
5138 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
5139 
5140 	rdev_for_each(rdev, mddev) {
5141 		raid_disk = rdev->raid_disk;
5142 		if (raid_disk >= max_disks
5143 		    || raid_disk < 0)
5144 			continue;
5145 		disk = conf->disks + raid_disk;
5146 
5147 		if (test_bit(Replacement, &rdev->flags)) {
5148 			if (disk->replacement)
5149 				goto abort;
5150 			disk->replacement = rdev;
5151 		} else {
5152 			if (disk->rdev)
5153 				goto abort;
5154 			disk->rdev = rdev;
5155 		}
5156 
5157 		if (test_bit(In_sync, &rdev->flags)) {
5158 			char b[BDEVNAME_SIZE];
5159 			printk(KERN_INFO "md/raid:%s: device %s operational as raid"
5160 			       " disk %d\n",
5161 			       mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
5162 		} else if (rdev->saved_raid_disk != raid_disk)
5163 			/* Cannot rely on bitmap to complete recovery */
5164 			conf->fullsync = 1;
5165 	}
5166 
5167 	conf->chunk_sectors = mddev->new_chunk_sectors;
5168 	conf->level = mddev->new_level;
5169 	if (conf->level == 6)
5170 		conf->max_degraded = 2;
5171 	else
5172 		conf->max_degraded = 1;
5173 	conf->algorithm = mddev->new_layout;
5174 	conf->max_nr_stripes = NR_STRIPES;
5175 	conf->reshape_progress = mddev->reshape_position;
5176 	if (conf->reshape_progress != MaxSector) {
5177 		conf->prev_chunk_sectors = mddev->chunk_sectors;
5178 		conf->prev_algo = mddev->layout;
5179 	}
5180 
5181 	memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
5182 		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
5183 	if (grow_stripes(conf, conf->max_nr_stripes)) {
5184 		printk(KERN_ERR
5185 		       "md/raid:%s: couldn't allocate %dkB for buffers\n",
5186 		       mdname(mddev), memory);
5187 		goto abort;
5188 	} else
5189 		printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
5190 		       mdname(mddev), memory);
5191 
5192 	sprintf(pers_name, "raid%d", mddev->new_level);
5193 	conf->thread = md_register_thread(raid5d, mddev, pers_name);
5194 	if (!conf->thread) {
5195 		printk(KERN_ERR
5196 		       "md/raid:%s: couldn't allocate thread.\n",
5197 		       mdname(mddev));
5198 		goto abort;
5199 	}
5200 
5201 	return conf;
5202 
5203  abort:
5204 	if (conf) {
5205 		free_conf(conf);
5206 		return ERR_PTR(-EIO);
5207 	} else
5208 		return ERR_PTR(-ENOMEM);
5209 }
5210 
5211 
5212 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
5213 {
5214 	switch (algo) {
5215 	case ALGORITHM_PARITY_0:
5216 		if (raid_disk < max_degraded)
5217 			return 1;
5218 		break;
5219 	case ALGORITHM_PARITY_N:
5220 		if (raid_disk >= raid_disks - max_degraded)
5221 			return 1;
5222 		break;
5223 	case ALGORITHM_PARITY_0_6:
5224 		if (raid_disk == 0 ||
5225 		    raid_disk == raid_disks - 1)
5226 			return 1;
5227 		break;
5228 	case ALGORITHM_LEFT_ASYMMETRIC_6:
5229 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
5230 	case ALGORITHM_LEFT_SYMMETRIC_6:
5231 	case ALGORITHM_RIGHT_SYMMETRIC_6:
5232 		if (raid_disk == raid_disks - 1)
5233 			return 1;
5234 	}
5235 	return 0;
5236 }
5237 
5238 static int run(struct mddev *mddev)
5239 {
5240 	struct r5conf *conf;
5241 	int working_disks = 0;
5242 	int dirty_parity_disks = 0;
5243 	struct md_rdev *rdev;
5244 	sector_t reshape_offset = 0;
5245 	int i;
5246 	long long min_offset_diff = 0;
5247 	int first = 1;
5248 
5249 	if (mddev->recovery_cp != MaxSector)
5250 		printk(KERN_NOTICE "md/raid:%s: not clean"
5251 		       " -- starting background reconstruction\n",
5252 		       mdname(mddev));
5253 
5254 	rdev_for_each(rdev, mddev) {
5255 		long long diff;
5256 		if (rdev->raid_disk < 0)
5257 			continue;
5258 		diff = (rdev->new_data_offset - rdev->data_offset);
5259 		if (first) {
5260 			min_offset_diff = diff;
5261 			first = 0;
5262 		} else if (mddev->reshape_backwards &&
5263 			 diff < min_offset_diff)
5264 			min_offset_diff = diff;
5265 		else if (!mddev->reshape_backwards &&
5266 			 diff > min_offset_diff)
5267 			min_offset_diff = diff;
5268 	}
5269 
5270 	if (mddev->reshape_position != MaxSector) {
5271 		/* Check that we can continue the reshape.
5272 		 * Difficulties arise if the stripe we would write to
5273 		 * next is at or after the stripe we would read from next.
5274 		 * For a reshape that changes the number of devices, this
5275 		 * is only possible for a very short time, and mdadm makes
5276 		 * sure that time appears to have past before assembling
5277 		 * the array.  So we fail if that time hasn't passed.
5278 		 * For a reshape that keeps the number of devices the same
5279 		 * mdadm must be monitoring the reshape can keeping the
5280 		 * critical areas read-only and backed up.  It will start
5281 		 * the array in read-only mode, so we check for that.
5282 		 */
5283 		sector_t here_new, here_old;
5284 		int old_disks;
5285 		int max_degraded = (mddev->level == 6 ? 2 : 1);
5286 
5287 		if (mddev->new_level != mddev->level) {
5288 			printk(KERN_ERR "md/raid:%s: unsupported reshape "
5289 			       "required - aborting.\n",
5290 			       mdname(mddev));
5291 			return -EINVAL;
5292 		}
5293 		old_disks = mddev->raid_disks - mddev->delta_disks;
5294 		/* reshape_position must be on a new-stripe boundary, and one
5295 		 * further up in new geometry must map after here in old
5296 		 * geometry.
5297 		 */
5298 		here_new = mddev->reshape_position;
5299 		if (sector_div(here_new, mddev->new_chunk_sectors *
5300 			       (mddev->raid_disks - max_degraded))) {
5301 			printk(KERN_ERR "md/raid:%s: reshape_position not "
5302 			       "on a stripe boundary\n", mdname(mddev));
5303 			return -EINVAL;
5304 		}
5305 		reshape_offset = here_new * mddev->new_chunk_sectors;
5306 		/* here_new is the stripe we will write to */
5307 		here_old = mddev->reshape_position;
5308 		sector_div(here_old, mddev->chunk_sectors *
5309 			   (old_disks-max_degraded));
5310 		/* here_old is the first stripe that we might need to read
5311 		 * from */
5312 		if (mddev->delta_disks == 0) {
5313 			if ((here_new * mddev->new_chunk_sectors !=
5314 			     here_old * mddev->chunk_sectors)) {
5315 				printk(KERN_ERR "md/raid:%s: reshape position is"
5316 				       " confused - aborting\n", mdname(mddev));
5317 				return -EINVAL;
5318 			}
5319 			/* We cannot be sure it is safe to start an in-place
5320 			 * reshape.  It is only safe if user-space is monitoring
5321 			 * and taking constant backups.
5322 			 * mdadm always starts a situation like this in
5323 			 * readonly mode so it can take control before
5324 			 * allowing any writes.  So just check for that.
5325 			 */
5326 			if (abs(min_offset_diff) >= mddev->chunk_sectors &&
5327 			    abs(min_offset_diff) >= mddev->new_chunk_sectors)
5328 				/* not really in-place - so OK */;
5329 			else if (mddev->ro == 0) {
5330 				printk(KERN_ERR "md/raid:%s: in-place reshape "
5331 				       "must be started in read-only mode "
5332 				       "- aborting\n",
5333 				       mdname(mddev));
5334 				return -EINVAL;
5335 			}
5336 		} else if (mddev->reshape_backwards
5337 		    ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=
5338 		       here_old * mddev->chunk_sectors)
5339 		    : (here_new * mddev->new_chunk_sectors >=
5340 		       here_old * mddev->chunk_sectors + (-min_offset_diff))) {
5341 			/* Reading from the same stripe as writing to - bad */
5342 			printk(KERN_ERR "md/raid:%s: reshape_position too early for "
5343 			       "auto-recovery - aborting.\n",
5344 			       mdname(mddev));
5345 			return -EINVAL;
5346 		}
5347 		printk(KERN_INFO "md/raid:%s: reshape will continue\n",
5348 		       mdname(mddev));
5349 		/* OK, we should be able to continue; */
5350 	} else {
5351 		BUG_ON(mddev->level != mddev->new_level);
5352 		BUG_ON(mddev->layout != mddev->new_layout);
5353 		BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
5354 		BUG_ON(mddev->delta_disks != 0);
5355 	}
5356 
5357 	if (mddev->private == NULL)
5358 		conf = setup_conf(mddev);
5359 	else
5360 		conf = mddev->private;
5361 
5362 	if (IS_ERR(conf))
5363 		return PTR_ERR(conf);
5364 
5365 	conf->min_offset_diff = min_offset_diff;
5366 	mddev->thread = conf->thread;
5367 	conf->thread = NULL;
5368 	mddev->private = conf;
5369 
5370 	for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
5371 	     i++) {
5372 		rdev = conf->disks[i].rdev;
5373 		if (!rdev && conf->disks[i].replacement) {
5374 			/* The replacement is all we have yet */
5375 			rdev = conf->disks[i].replacement;
5376 			conf->disks[i].replacement = NULL;
5377 			clear_bit(Replacement, &rdev->flags);
5378 			conf->disks[i].rdev = rdev;
5379 		}
5380 		if (!rdev)
5381 			continue;
5382 		if (conf->disks[i].replacement &&
5383 		    conf->reshape_progress != MaxSector) {
5384 			/* replacements and reshape simply do not mix. */
5385 			printk(KERN_ERR "md: cannot handle concurrent "
5386 			       "replacement and reshape.\n");
5387 			goto abort;
5388 		}
5389 		if (test_bit(In_sync, &rdev->flags)) {
5390 			working_disks++;
5391 			continue;
5392 		}
5393 		/* This disc is not fully in-sync.  However if it
5394 		 * just stored parity (beyond the recovery_offset),
5395 		 * when we don't need to be concerned about the
5396 		 * array being dirty.
5397 		 * When reshape goes 'backwards', we never have
5398 		 * partially completed devices, so we only need
5399 		 * to worry about reshape going forwards.
5400 		 */
5401 		/* Hack because v0.91 doesn't store recovery_offset properly. */
5402 		if (mddev->major_version == 0 &&
5403 		    mddev->minor_version > 90)
5404 			rdev->recovery_offset = reshape_offset;
5405 
5406 		if (rdev->recovery_offset < reshape_offset) {
5407 			/* We need to check old and new layout */
5408 			if (!only_parity(rdev->raid_disk,
5409 					 conf->algorithm,
5410 					 conf->raid_disks,
5411 					 conf->max_degraded))
5412 				continue;
5413 		}
5414 		if (!only_parity(rdev->raid_disk,
5415 				 conf->prev_algo,
5416 				 conf->previous_raid_disks,
5417 				 conf->max_degraded))
5418 			continue;
5419 		dirty_parity_disks++;
5420 	}
5421 
5422 	/*
5423 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
5424 	 */
5425 	mddev->degraded = calc_degraded(conf);
5426 
5427 	if (has_failed(conf)) {
5428 		printk(KERN_ERR "md/raid:%s: not enough operational devices"
5429 			" (%d/%d failed)\n",
5430 			mdname(mddev), mddev->degraded, conf->raid_disks);
5431 		goto abort;
5432 	}
5433 
5434 	/* device size must be a multiple of chunk size */
5435 	mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
5436 	mddev->resync_max_sectors = mddev->dev_sectors;
5437 
5438 	if (mddev->degraded > dirty_parity_disks &&
5439 	    mddev->recovery_cp != MaxSector) {
5440 		if (mddev->ok_start_degraded)
5441 			printk(KERN_WARNING
5442 			       "md/raid:%s: starting dirty degraded array"
5443 			       " - data corruption possible.\n",
5444 			       mdname(mddev));
5445 		else {
5446 			printk(KERN_ERR
5447 			       "md/raid:%s: cannot start dirty degraded array.\n",
5448 			       mdname(mddev));
5449 			goto abort;
5450 		}
5451 	}
5452 
5453 	if (mddev->degraded == 0)
5454 		printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
5455 		       " devices, algorithm %d\n", mdname(mddev), conf->level,
5456 		       mddev->raid_disks-mddev->degraded, mddev->raid_disks,
5457 		       mddev->new_layout);
5458 	else
5459 		printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
5460 		       " out of %d devices, algorithm %d\n",
5461 		       mdname(mddev), conf->level,
5462 		       mddev->raid_disks - mddev->degraded,
5463 		       mddev->raid_disks, mddev->new_layout);
5464 
5465 	print_raid5_conf(conf);
5466 
5467 	if (conf->reshape_progress != MaxSector) {
5468 		conf->reshape_safe = conf->reshape_progress;
5469 		atomic_set(&conf->reshape_stripes, 0);
5470 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
5471 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
5472 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
5473 		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
5474 		mddev->sync_thread = md_register_thread(md_do_sync, mddev,
5475 							"reshape");
5476 	}
5477 
5478 
5479 	/* Ok, everything is just fine now */
5480 	if (mddev->to_remove == &raid5_attrs_group)
5481 		mddev->to_remove = NULL;
5482 	else if (mddev->kobj.sd &&
5483 	    sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
5484 		printk(KERN_WARNING
5485 		       "raid5: failed to create sysfs attributes for %s\n",
5486 		       mdname(mddev));
5487 	md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
5488 
5489 	if (mddev->queue) {
5490 		int chunk_size;
5491 		bool discard_supported = true;
5492 		/* read-ahead size must cover two whole stripes, which
5493 		 * is 2 * (datadisks) * chunksize where 'n' is the
5494 		 * number of raid devices
5495 		 */
5496 		int data_disks = conf->previous_raid_disks - conf->max_degraded;
5497 		int stripe = data_disks *
5498 			((mddev->chunk_sectors << 9) / PAGE_SIZE);
5499 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
5500 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
5501 
5502 		blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
5503 
5504 		mddev->queue->backing_dev_info.congested_data = mddev;
5505 		mddev->queue->backing_dev_info.congested_fn = raid5_congested;
5506 
5507 		chunk_size = mddev->chunk_sectors << 9;
5508 		blk_queue_io_min(mddev->queue, chunk_size);
5509 		blk_queue_io_opt(mddev->queue, chunk_size *
5510 				 (conf->raid_disks - conf->max_degraded));
5511 		/*
5512 		 * We can only discard a whole stripe. It doesn't make sense to
5513 		 * discard data disk but write parity disk
5514 		 */
5515 		stripe = stripe * PAGE_SIZE;
5516 		/* Round up to power of 2, as discard handling
5517 		 * currently assumes that */
5518 		while ((stripe-1) & stripe)
5519 			stripe = (stripe | (stripe-1)) + 1;
5520 		mddev->queue->limits.discard_alignment = stripe;
5521 		mddev->queue->limits.discard_granularity = stripe;
5522 		/*
5523 		 * unaligned part of discard request will be ignored, so can't
5524 		 * guarantee discard_zerors_data
5525 		 */
5526 		mddev->queue->limits.discard_zeroes_data = 0;
5527 
5528 		rdev_for_each(rdev, mddev) {
5529 			disk_stack_limits(mddev->gendisk, rdev->bdev,
5530 					  rdev->data_offset << 9);
5531 			disk_stack_limits(mddev->gendisk, rdev->bdev,
5532 					  rdev->new_data_offset << 9);
5533 			/*
5534 			 * discard_zeroes_data is required, otherwise data
5535 			 * could be lost. Consider a scenario: discard a stripe
5536 			 * (the stripe could be inconsistent if
5537 			 * discard_zeroes_data is 0); write one disk of the
5538 			 * stripe (the stripe could be inconsistent again
5539 			 * depending on which disks are used to calculate
5540 			 * parity); the disk is broken; The stripe data of this
5541 			 * disk is lost.
5542 			 */
5543 			if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
5544 			    !bdev_get_queue(rdev->bdev)->
5545 						limits.discard_zeroes_data)
5546 				discard_supported = false;
5547 		}
5548 
5549 		if (discard_supported &&
5550 		   mddev->queue->limits.max_discard_sectors >= stripe &&
5551 		   mddev->queue->limits.discard_granularity >= stripe)
5552 			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
5553 						mddev->queue);
5554 		else
5555 			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
5556 						mddev->queue);
5557 	}
5558 
5559 	return 0;
5560 abort:
5561 	md_unregister_thread(&mddev->thread);
5562 	print_raid5_conf(conf);
5563 	free_conf(conf);
5564 	mddev->private = NULL;
5565 	printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
5566 	return -EIO;
5567 }
5568 
5569 static int stop(struct mddev *mddev)
5570 {
5571 	struct r5conf *conf = mddev->private;
5572 
5573 	md_unregister_thread(&mddev->thread);
5574 	if (mddev->queue)
5575 		mddev->queue->backing_dev_info.congested_fn = NULL;
5576 	free_conf(conf);
5577 	mddev->private = NULL;
5578 	mddev->to_remove = &raid5_attrs_group;
5579 	return 0;
5580 }
5581 
5582 static void status(struct seq_file *seq, struct mddev *mddev)
5583 {
5584 	struct r5conf *conf = mddev->private;
5585 	int i;
5586 
5587 	seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
5588 		mddev->chunk_sectors / 2, mddev->layout);
5589 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
5590 	for (i = 0; i < conf->raid_disks; i++)
5591 		seq_printf (seq, "%s",
5592 			       conf->disks[i].rdev &&
5593 			       test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
5594 	seq_printf (seq, "]");
5595 }
5596 
5597 static void print_raid5_conf (struct r5conf *conf)
5598 {
5599 	int i;
5600 	struct disk_info *tmp;
5601 
5602 	printk(KERN_DEBUG "RAID conf printout:\n");
5603 	if (!conf) {
5604 		printk("(conf==NULL)\n");
5605 		return;
5606 	}
5607 	printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
5608 	       conf->raid_disks,
5609 	       conf->raid_disks - conf->mddev->degraded);
5610 
5611 	for (i = 0; i < conf->raid_disks; i++) {
5612 		char b[BDEVNAME_SIZE];
5613 		tmp = conf->disks + i;
5614 		if (tmp->rdev)
5615 			printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
5616 			       i, !test_bit(Faulty, &tmp->rdev->flags),
5617 			       bdevname(tmp->rdev->bdev, b));
5618 	}
5619 }
5620 
5621 static int raid5_spare_active(struct mddev *mddev)
5622 {
5623 	int i;
5624 	struct r5conf *conf = mddev->private;
5625 	struct disk_info *tmp;
5626 	int count = 0;
5627 	unsigned long flags;
5628 
5629 	for (i = 0; i < conf->raid_disks; i++) {
5630 		tmp = conf->disks + i;
5631 		if (tmp->replacement
5632 		    && tmp->replacement->recovery_offset == MaxSector
5633 		    && !test_bit(Faulty, &tmp->replacement->flags)
5634 		    && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
5635 			/* Replacement has just become active. */
5636 			if (!tmp->rdev
5637 			    || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
5638 				count++;
5639 			if (tmp->rdev) {
5640 				/* Replaced device not technically faulty,
5641 				 * but we need to be sure it gets removed
5642 				 * and never re-added.
5643 				 */
5644 				set_bit(Faulty, &tmp->rdev->flags);
5645 				sysfs_notify_dirent_safe(
5646 					tmp->rdev->sysfs_state);
5647 			}
5648 			sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
5649 		} else if (tmp->rdev
5650 		    && tmp->rdev->recovery_offset == MaxSector
5651 		    && !test_bit(Faulty, &tmp->rdev->flags)
5652 		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
5653 			count++;
5654 			sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
5655 		}
5656 	}
5657 	spin_lock_irqsave(&conf->device_lock, flags);
5658 	mddev->degraded = calc_degraded(conf);
5659 	spin_unlock_irqrestore(&conf->device_lock, flags);
5660 	print_raid5_conf(conf);
5661 	return count;
5662 }
5663 
5664 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
5665 {
5666 	struct r5conf *conf = mddev->private;
5667 	int err = 0;
5668 	int number = rdev->raid_disk;
5669 	struct md_rdev **rdevp;
5670 	struct disk_info *p = conf->disks + number;
5671 
5672 	print_raid5_conf(conf);
5673 	if (rdev == p->rdev)
5674 		rdevp = &p->rdev;
5675 	else if (rdev == p->replacement)
5676 		rdevp = &p->replacement;
5677 	else
5678 		return 0;
5679 
5680 	if (number >= conf->raid_disks &&
5681 	    conf->reshape_progress == MaxSector)
5682 		clear_bit(In_sync, &rdev->flags);
5683 
5684 	if (test_bit(In_sync, &rdev->flags) ||
5685 	    atomic_read(&rdev->nr_pending)) {
5686 		err = -EBUSY;
5687 		goto abort;
5688 	}
5689 	/* Only remove non-faulty devices if recovery
5690 	 * isn't possible.
5691 	 */
5692 	if (!test_bit(Faulty, &rdev->flags) &&
5693 	    mddev->recovery_disabled != conf->recovery_disabled &&
5694 	    !has_failed(conf) &&
5695 	    (!p->replacement || p->replacement == rdev) &&
5696 	    number < conf->raid_disks) {
5697 		err = -EBUSY;
5698 		goto abort;
5699 	}
5700 	*rdevp = NULL;
5701 	synchronize_rcu();
5702 	if (atomic_read(&rdev->nr_pending)) {
5703 		/* lost the race, try later */
5704 		err = -EBUSY;
5705 		*rdevp = rdev;
5706 	} else if (p->replacement) {
5707 		/* We must have just cleared 'rdev' */
5708 		p->rdev = p->replacement;
5709 		clear_bit(Replacement, &p->replacement->flags);
5710 		smp_mb(); /* Make sure other CPUs may see both as identical
5711 			   * but will never see neither - if they are careful
5712 			   */
5713 		p->replacement = NULL;
5714 		clear_bit(WantReplacement, &rdev->flags);
5715 	} else
5716 		/* We might have just removed the Replacement as faulty-
5717 		 * clear the bit just in case
5718 		 */
5719 		clear_bit(WantReplacement, &rdev->flags);
5720 abort:
5721 
5722 	print_raid5_conf(conf);
5723 	return err;
5724 }
5725 
5726 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
5727 {
5728 	struct r5conf *conf = mddev->private;
5729 	int err = -EEXIST;
5730 	int disk;
5731 	struct disk_info *p;
5732 	int first = 0;
5733 	int last = conf->raid_disks - 1;
5734 
5735 	if (mddev->recovery_disabled == conf->recovery_disabled)
5736 		return -EBUSY;
5737 
5738 	if (rdev->saved_raid_disk < 0 && has_failed(conf))
5739 		/* no point adding a device */
5740 		return -EINVAL;
5741 
5742 	if (rdev->raid_disk >= 0)
5743 		first = last = rdev->raid_disk;
5744 
5745 	/*
5746 	 * find the disk ... but prefer rdev->saved_raid_disk
5747 	 * if possible.
5748 	 */
5749 	if (rdev->saved_raid_disk >= 0 &&
5750 	    rdev->saved_raid_disk >= first &&
5751 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
5752 		first = rdev->saved_raid_disk;
5753 
5754 	for (disk = first; disk <= last; disk++) {
5755 		p = conf->disks + disk;
5756 		if (p->rdev == NULL) {
5757 			clear_bit(In_sync, &rdev->flags);
5758 			rdev->raid_disk = disk;
5759 			err = 0;
5760 			if (rdev->saved_raid_disk != disk)
5761 				conf->fullsync = 1;
5762 			rcu_assign_pointer(p->rdev, rdev);
5763 			goto out;
5764 		}
5765 	}
5766 	for (disk = first; disk <= last; disk++) {
5767 		p = conf->disks + disk;
5768 		if (test_bit(WantReplacement, &p->rdev->flags) &&
5769 		    p->replacement == NULL) {
5770 			clear_bit(In_sync, &rdev->flags);
5771 			set_bit(Replacement, &rdev->flags);
5772 			rdev->raid_disk = disk;
5773 			err = 0;
5774 			conf->fullsync = 1;
5775 			rcu_assign_pointer(p->replacement, rdev);
5776 			break;
5777 		}
5778 	}
5779 out:
5780 	print_raid5_conf(conf);
5781 	return err;
5782 }
5783 
5784 static int raid5_resize(struct mddev *mddev, sector_t sectors)
5785 {
5786 	/* no resync is happening, and there is enough space
5787 	 * on all devices, so we can resize.
5788 	 * We need to make sure resync covers any new space.
5789 	 * If the array is shrinking we should possibly wait until
5790 	 * any io in the removed space completes, but it hardly seems
5791 	 * worth it.
5792 	 */
5793 	sector_t newsize;
5794 	sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5795 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
5796 	if (mddev->external_size &&
5797 	    mddev->array_sectors > newsize)
5798 		return -EINVAL;
5799 	if (mddev->bitmap) {
5800 		int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
5801 		if (ret)
5802 			return ret;
5803 	}
5804 	md_set_array_sectors(mddev, newsize);
5805 	set_capacity(mddev->gendisk, mddev->array_sectors);
5806 	revalidate_disk(mddev->gendisk);
5807 	if (sectors > mddev->dev_sectors &&
5808 	    mddev->recovery_cp > mddev->dev_sectors) {
5809 		mddev->recovery_cp = mddev->dev_sectors;
5810 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
5811 	}
5812 	mddev->dev_sectors = sectors;
5813 	mddev->resync_max_sectors = sectors;
5814 	return 0;
5815 }
5816 
5817 static int check_stripe_cache(struct mddev *mddev)
5818 {
5819 	/* Can only proceed if there are plenty of stripe_heads.
5820 	 * We need a minimum of one full stripe,, and for sensible progress
5821 	 * it is best to have about 4 times that.
5822 	 * If we require 4 times, then the default 256 4K stripe_heads will
5823 	 * allow for chunk sizes up to 256K, which is probably OK.
5824 	 * If the chunk size is greater, user-space should request more
5825 	 * stripe_heads first.
5826 	 */
5827 	struct r5conf *conf = mddev->private;
5828 	if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
5829 	    > conf->max_nr_stripes ||
5830 	    ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
5831 	    > conf->max_nr_stripes) {
5832 		printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
5833 		       mdname(mddev),
5834 		       ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
5835 			/ STRIPE_SIZE)*4);
5836 		return 0;
5837 	}
5838 	return 1;
5839 }
5840 
5841 static int check_reshape(struct mddev *mddev)
5842 {
5843 	struct r5conf *conf = mddev->private;
5844 
5845 	if (mddev->delta_disks == 0 &&
5846 	    mddev->new_layout == mddev->layout &&
5847 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
5848 		return 0; /* nothing to do */
5849 	if (has_failed(conf))
5850 		return -EINVAL;
5851 	if (mddev->delta_disks < 0) {
5852 		/* We might be able to shrink, but the devices must
5853 		 * be made bigger first.
5854 		 * For raid6, 4 is the minimum size.
5855 		 * Otherwise 2 is the minimum
5856 		 */
5857 		int min = 2;
5858 		if (mddev->level == 6)
5859 			min = 4;
5860 		if (mddev->raid_disks + mddev->delta_disks < min)
5861 			return -EINVAL;
5862 	}
5863 
5864 	if (!check_stripe_cache(mddev))
5865 		return -ENOSPC;
5866 
5867 	return resize_stripes(conf, (conf->previous_raid_disks
5868 				     + mddev->delta_disks));
5869 }
5870 
5871 static int raid5_start_reshape(struct mddev *mddev)
5872 {
5873 	struct r5conf *conf = mddev->private;
5874 	struct md_rdev *rdev;
5875 	int spares = 0;
5876 	unsigned long flags;
5877 
5878 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
5879 		return -EBUSY;
5880 
5881 	if (!check_stripe_cache(mddev))
5882 		return -ENOSPC;
5883 
5884 	if (has_failed(conf))
5885 		return -EINVAL;
5886 
5887 	rdev_for_each(rdev, mddev) {
5888 		if (!test_bit(In_sync, &rdev->flags)
5889 		    && !test_bit(Faulty, &rdev->flags))
5890 			spares++;
5891 	}
5892 
5893 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
5894 		/* Not enough devices even to make a degraded array
5895 		 * of that size
5896 		 */
5897 		return -EINVAL;
5898 
5899 	/* Refuse to reduce size of the array.  Any reductions in
5900 	 * array size must be through explicit setting of array_size
5901 	 * attribute.
5902 	 */
5903 	if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
5904 	    < mddev->array_sectors) {
5905 		printk(KERN_ERR "md/raid:%s: array size must be reduced "
5906 		       "before number of disks\n", mdname(mddev));
5907 		return -EINVAL;
5908 	}
5909 
5910 	atomic_set(&conf->reshape_stripes, 0);
5911 	spin_lock_irq(&conf->device_lock);
5912 	conf->previous_raid_disks = conf->raid_disks;
5913 	conf->raid_disks += mddev->delta_disks;
5914 	conf->prev_chunk_sectors = conf->chunk_sectors;
5915 	conf->chunk_sectors = mddev->new_chunk_sectors;
5916 	conf->prev_algo = conf->algorithm;
5917 	conf->algorithm = mddev->new_layout;
5918 	conf->generation++;
5919 	/* Code that selects data_offset needs to see the generation update
5920 	 * if reshape_progress has been set - so a memory barrier needed.
5921 	 */
5922 	smp_mb();
5923 	if (mddev->reshape_backwards)
5924 		conf->reshape_progress = raid5_size(mddev, 0, 0);
5925 	else
5926 		conf->reshape_progress = 0;
5927 	conf->reshape_safe = conf->reshape_progress;
5928 	spin_unlock_irq(&conf->device_lock);
5929 
5930 	/* Add some new drives, as many as will fit.
5931 	 * We know there are enough to make the newly sized array work.
5932 	 * Don't add devices if we are reducing the number of
5933 	 * devices in the array.  This is because it is not possible
5934 	 * to correctly record the "partially reconstructed" state of
5935 	 * such devices during the reshape and confusion could result.
5936 	 */
5937 	if (mddev->delta_disks >= 0) {
5938 		rdev_for_each(rdev, mddev)
5939 			if (rdev->raid_disk < 0 &&
5940 			    !test_bit(Faulty, &rdev->flags)) {
5941 				if (raid5_add_disk(mddev, rdev) == 0) {
5942 					if (rdev->raid_disk
5943 					    >= conf->previous_raid_disks)
5944 						set_bit(In_sync, &rdev->flags);
5945 					else
5946 						rdev->recovery_offset = 0;
5947 
5948 					if (sysfs_link_rdev(mddev, rdev))
5949 						/* Failure here is OK */;
5950 				}
5951 			} else if (rdev->raid_disk >= conf->previous_raid_disks
5952 				   && !test_bit(Faulty, &rdev->flags)) {
5953 				/* This is a spare that was manually added */
5954 				set_bit(In_sync, &rdev->flags);
5955 			}
5956 
5957 		/* When a reshape changes the number of devices,
5958 		 * ->degraded is measured against the larger of the
5959 		 * pre and post number of devices.
5960 		 */
5961 		spin_lock_irqsave(&conf->device_lock, flags);
5962 		mddev->degraded = calc_degraded(conf);
5963 		spin_unlock_irqrestore(&conf->device_lock, flags);
5964 	}
5965 	mddev->raid_disks = conf->raid_disks;
5966 	mddev->reshape_position = conf->reshape_progress;
5967 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
5968 
5969 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
5970 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
5971 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
5972 	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
5973 	mddev->sync_thread = md_register_thread(md_do_sync, mddev,
5974 						"reshape");
5975 	if (!mddev->sync_thread) {
5976 		mddev->recovery = 0;
5977 		spin_lock_irq(&conf->device_lock);
5978 		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
5979 		rdev_for_each(rdev, mddev)
5980 			rdev->new_data_offset = rdev->data_offset;
5981 		smp_wmb();
5982 		conf->reshape_progress = MaxSector;
5983 		mddev->reshape_position = MaxSector;
5984 		spin_unlock_irq(&conf->device_lock);
5985 		return -EAGAIN;
5986 	}
5987 	conf->reshape_checkpoint = jiffies;
5988 	md_wakeup_thread(mddev->sync_thread);
5989 	md_new_event(mddev);
5990 	return 0;
5991 }
5992 
5993 /* This is called from the reshape thread and should make any
5994  * changes needed in 'conf'
5995  */
5996 static void end_reshape(struct r5conf *conf)
5997 {
5998 
5999 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
6000 		struct md_rdev *rdev;
6001 
6002 		spin_lock_irq(&conf->device_lock);
6003 		conf->previous_raid_disks = conf->raid_disks;
6004 		rdev_for_each(rdev, conf->mddev)
6005 			rdev->data_offset = rdev->new_data_offset;
6006 		smp_wmb();
6007 		conf->reshape_progress = MaxSector;
6008 		spin_unlock_irq(&conf->device_lock);
6009 		wake_up(&conf->wait_for_overlap);
6010 
6011 		/* read-ahead size must cover two whole stripes, which is
6012 		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
6013 		 */
6014 		if (conf->mddev->queue) {
6015 			int data_disks = conf->raid_disks - conf->max_degraded;
6016 			int stripe = data_disks * ((conf->chunk_sectors << 9)
6017 						   / PAGE_SIZE);
6018 			if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6019 				conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6020 		}
6021 	}
6022 }
6023 
6024 /* This is called from the raid5d thread with mddev_lock held.
6025  * It makes config changes to the device.
6026  */
6027 static void raid5_finish_reshape(struct mddev *mddev)
6028 {
6029 	struct r5conf *conf = mddev->private;
6030 
6031 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
6032 
6033 		if (mddev->delta_disks > 0) {
6034 			md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6035 			set_capacity(mddev->gendisk, mddev->array_sectors);
6036 			revalidate_disk(mddev->gendisk);
6037 		} else {
6038 			int d;
6039 			spin_lock_irq(&conf->device_lock);
6040 			mddev->degraded = calc_degraded(conf);
6041 			spin_unlock_irq(&conf->device_lock);
6042 			for (d = conf->raid_disks ;
6043 			     d < conf->raid_disks - mddev->delta_disks;
6044 			     d++) {
6045 				struct md_rdev *rdev = conf->disks[d].rdev;
6046 				if (rdev)
6047 					clear_bit(In_sync, &rdev->flags);
6048 				rdev = conf->disks[d].replacement;
6049 				if (rdev)
6050 					clear_bit(In_sync, &rdev->flags);
6051 			}
6052 		}
6053 		mddev->layout = conf->algorithm;
6054 		mddev->chunk_sectors = conf->chunk_sectors;
6055 		mddev->reshape_position = MaxSector;
6056 		mddev->delta_disks = 0;
6057 		mddev->reshape_backwards = 0;
6058 	}
6059 }
6060 
6061 static void raid5_quiesce(struct mddev *mddev, int state)
6062 {
6063 	struct r5conf *conf = mddev->private;
6064 
6065 	switch(state) {
6066 	case 2: /* resume for a suspend */
6067 		wake_up(&conf->wait_for_overlap);
6068 		break;
6069 
6070 	case 1: /* stop all writes */
6071 		spin_lock_irq(&conf->device_lock);
6072 		/* '2' tells resync/reshape to pause so that all
6073 		 * active stripes can drain
6074 		 */
6075 		conf->quiesce = 2;
6076 		wait_event_lock_irq(conf->wait_for_stripe,
6077 				    atomic_read(&conf->active_stripes) == 0 &&
6078 				    atomic_read(&conf->active_aligned_reads) == 0,
6079 				    conf->device_lock);
6080 		conf->quiesce = 1;
6081 		spin_unlock_irq(&conf->device_lock);
6082 		/* allow reshape to continue */
6083 		wake_up(&conf->wait_for_overlap);
6084 		break;
6085 
6086 	case 0: /* re-enable writes */
6087 		spin_lock_irq(&conf->device_lock);
6088 		conf->quiesce = 0;
6089 		wake_up(&conf->wait_for_stripe);
6090 		wake_up(&conf->wait_for_overlap);
6091 		spin_unlock_irq(&conf->device_lock);
6092 		break;
6093 	}
6094 }
6095 
6096 
6097 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
6098 {
6099 	struct r0conf *raid0_conf = mddev->private;
6100 	sector_t sectors;
6101 
6102 	/* for raid0 takeover only one zone is supported */
6103 	if (raid0_conf->nr_strip_zones > 1) {
6104 		printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
6105 		       mdname(mddev));
6106 		return ERR_PTR(-EINVAL);
6107 	}
6108 
6109 	sectors = raid0_conf->strip_zone[0].zone_end;
6110 	sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
6111 	mddev->dev_sectors = sectors;
6112 	mddev->new_level = level;
6113 	mddev->new_layout = ALGORITHM_PARITY_N;
6114 	mddev->new_chunk_sectors = mddev->chunk_sectors;
6115 	mddev->raid_disks += 1;
6116 	mddev->delta_disks = 1;
6117 	/* make sure it will be not marked as dirty */
6118 	mddev->recovery_cp = MaxSector;
6119 
6120 	return setup_conf(mddev);
6121 }
6122 
6123 
6124 static void *raid5_takeover_raid1(struct mddev *mddev)
6125 {
6126 	int chunksect;
6127 
6128 	if (mddev->raid_disks != 2 ||
6129 	    mddev->degraded > 1)
6130 		return ERR_PTR(-EINVAL);
6131 
6132 	/* Should check if there are write-behind devices? */
6133 
6134 	chunksect = 64*2; /* 64K by default */
6135 
6136 	/* The array must be an exact multiple of chunksize */
6137 	while (chunksect && (mddev->array_sectors & (chunksect-1)))
6138 		chunksect >>= 1;
6139 
6140 	if ((chunksect<<9) < STRIPE_SIZE)
6141 		/* array size does not allow a suitable chunk size */
6142 		return ERR_PTR(-EINVAL);
6143 
6144 	mddev->new_level = 5;
6145 	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
6146 	mddev->new_chunk_sectors = chunksect;
6147 
6148 	return setup_conf(mddev);
6149 }
6150 
6151 static void *raid5_takeover_raid6(struct mddev *mddev)
6152 {
6153 	int new_layout;
6154 
6155 	switch (mddev->layout) {
6156 	case ALGORITHM_LEFT_ASYMMETRIC_6:
6157 		new_layout = ALGORITHM_LEFT_ASYMMETRIC;
6158 		break;
6159 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
6160 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
6161 		break;
6162 	case ALGORITHM_LEFT_SYMMETRIC_6:
6163 		new_layout = ALGORITHM_LEFT_SYMMETRIC;
6164 		break;
6165 	case ALGORITHM_RIGHT_SYMMETRIC_6:
6166 		new_layout = ALGORITHM_RIGHT_SYMMETRIC;
6167 		break;
6168 	case ALGORITHM_PARITY_0_6:
6169 		new_layout = ALGORITHM_PARITY_0;
6170 		break;
6171 	case ALGORITHM_PARITY_N:
6172 		new_layout = ALGORITHM_PARITY_N;
6173 		break;
6174 	default:
6175 		return ERR_PTR(-EINVAL);
6176 	}
6177 	mddev->new_level = 5;
6178 	mddev->new_layout = new_layout;
6179 	mddev->delta_disks = -1;
6180 	mddev->raid_disks -= 1;
6181 	return setup_conf(mddev);
6182 }
6183 
6184 
6185 static int raid5_check_reshape(struct mddev *mddev)
6186 {
6187 	/* For a 2-drive array, the layout and chunk size can be changed
6188 	 * immediately as not restriping is needed.
6189 	 * For larger arrays we record the new value - after validation
6190 	 * to be used by a reshape pass.
6191 	 */
6192 	struct r5conf *conf = mddev->private;
6193 	int new_chunk = mddev->new_chunk_sectors;
6194 
6195 	if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
6196 		return -EINVAL;
6197 	if (new_chunk > 0) {
6198 		if (!is_power_of_2(new_chunk))
6199 			return -EINVAL;
6200 		if (new_chunk < (PAGE_SIZE>>9))
6201 			return -EINVAL;
6202 		if (mddev->array_sectors & (new_chunk-1))
6203 			/* not factor of array size */
6204 			return -EINVAL;
6205 	}
6206 
6207 	/* They look valid */
6208 
6209 	if (mddev->raid_disks == 2) {
6210 		/* can make the change immediately */
6211 		if (mddev->new_layout >= 0) {
6212 			conf->algorithm = mddev->new_layout;
6213 			mddev->layout = mddev->new_layout;
6214 		}
6215 		if (new_chunk > 0) {
6216 			conf->chunk_sectors = new_chunk ;
6217 			mddev->chunk_sectors = new_chunk;
6218 		}
6219 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
6220 		md_wakeup_thread(mddev->thread);
6221 	}
6222 	return check_reshape(mddev);
6223 }
6224 
6225 static int raid6_check_reshape(struct mddev *mddev)
6226 {
6227 	int new_chunk = mddev->new_chunk_sectors;
6228 
6229 	if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
6230 		return -EINVAL;
6231 	if (new_chunk > 0) {
6232 		if (!is_power_of_2(new_chunk))
6233 			return -EINVAL;
6234 		if (new_chunk < (PAGE_SIZE >> 9))
6235 			return -EINVAL;
6236 		if (mddev->array_sectors & (new_chunk-1))
6237 			/* not factor of array size */
6238 			return -EINVAL;
6239 	}
6240 
6241 	/* They look valid */
6242 	return check_reshape(mddev);
6243 }
6244 
6245 static void *raid5_takeover(struct mddev *mddev)
6246 {
6247 	/* raid5 can take over:
6248 	 *  raid0 - if there is only one strip zone - make it a raid4 layout
6249 	 *  raid1 - if there are two drives.  We need to know the chunk size
6250 	 *  raid4 - trivial - just use a raid4 layout.
6251 	 *  raid6 - Providing it is a *_6 layout
6252 	 */
6253 	if (mddev->level == 0)
6254 		return raid45_takeover_raid0(mddev, 5);
6255 	if (mddev->level == 1)
6256 		return raid5_takeover_raid1(mddev);
6257 	if (mddev->level == 4) {
6258 		mddev->new_layout = ALGORITHM_PARITY_N;
6259 		mddev->new_level = 5;
6260 		return setup_conf(mddev);
6261 	}
6262 	if (mddev->level == 6)
6263 		return raid5_takeover_raid6(mddev);
6264 
6265 	return ERR_PTR(-EINVAL);
6266 }
6267 
6268 static void *raid4_takeover(struct mddev *mddev)
6269 {
6270 	/* raid4 can take over:
6271 	 *  raid0 - if there is only one strip zone
6272 	 *  raid5 - if layout is right
6273 	 */
6274 	if (mddev->level == 0)
6275 		return raid45_takeover_raid0(mddev, 4);
6276 	if (mddev->level == 5 &&
6277 	    mddev->layout == ALGORITHM_PARITY_N) {
6278 		mddev->new_layout = 0;
6279 		mddev->new_level = 4;
6280 		return setup_conf(mddev);
6281 	}
6282 	return ERR_PTR(-EINVAL);
6283 }
6284 
6285 static struct md_personality raid5_personality;
6286 
6287 static void *raid6_takeover(struct mddev *mddev)
6288 {
6289 	/* Currently can only take over a raid5.  We map the
6290 	 * personality to an equivalent raid6 personality
6291 	 * with the Q block at the end.
6292 	 */
6293 	int new_layout;
6294 
6295 	if (mddev->pers != &raid5_personality)
6296 		return ERR_PTR(-EINVAL);
6297 	if (mddev->degraded > 1)
6298 		return ERR_PTR(-EINVAL);
6299 	if (mddev->raid_disks > 253)
6300 		return ERR_PTR(-EINVAL);
6301 	if (mddev->raid_disks < 3)
6302 		return ERR_PTR(-EINVAL);
6303 
6304 	switch (mddev->layout) {
6305 	case ALGORITHM_LEFT_ASYMMETRIC:
6306 		new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
6307 		break;
6308 	case ALGORITHM_RIGHT_ASYMMETRIC:
6309 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
6310 		break;
6311 	case ALGORITHM_LEFT_SYMMETRIC:
6312 		new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
6313 		break;
6314 	case ALGORITHM_RIGHT_SYMMETRIC:
6315 		new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
6316 		break;
6317 	case ALGORITHM_PARITY_0:
6318 		new_layout = ALGORITHM_PARITY_0_6;
6319 		break;
6320 	case ALGORITHM_PARITY_N:
6321 		new_layout = ALGORITHM_PARITY_N;
6322 		break;
6323 	default:
6324 		return ERR_PTR(-EINVAL);
6325 	}
6326 	mddev->new_level = 6;
6327 	mddev->new_layout = new_layout;
6328 	mddev->delta_disks = 1;
6329 	mddev->raid_disks += 1;
6330 	return setup_conf(mddev);
6331 }
6332 
6333 
6334 static struct md_personality raid6_personality =
6335 {
6336 	.name		= "raid6",
6337 	.level		= 6,
6338 	.owner		= THIS_MODULE,
6339 	.make_request	= make_request,
6340 	.run		= run,
6341 	.stop		= stop,
6342 	.status		= status,
6343 	.error_handler	= error,
6344 	.hot_add_disk	= raid5_add_disk,
6345 	.hot_remove_disk= raid5_remove_disk,
6346 	.spare_active	= raid5_spare_active,
6347 	.sync_request	= sync_request,
6348 	.resize		= raid5_resize,
6349 	.size		= raid5_size,
6350 	.check_reshape	= raid6_check_reshape,
6351 	.start_reshape  = raid5_start_reshape,
6352 	.finish_reshape = raid5_finish_reshape,
6353 	.quiesce	= raid5_quiesce,
6354 	.takeover	= raid6_takeover,
6355 };
6356 static struct md_personality raid5_personality =
6357 {
6358 	.name		= "raid5",
6359 	.level		= 5,
6360 	.owner		= THIS_MODULE,
6361 	.make_request	= make_request,
6362 	.run		= run,
6363 	.stop		= stop,
6364 	.status		= status,
6365 	.error_handler	= error,
6366 	.hot_add_disk	= raid5_add_disk,
6367 	.hot_remove_disk= raid5_remove_disk,
6368 	.spare_active	= raid5_spare_active,
6369 	.sync_request	= sync_request,
6370 	.resize		= raid5_resize,
6371 	.size		= raid5_size,
6372 	.check_reshape	= raid5_check_reshape,
6373 	.start_reshape  = raid5_start_reshape,
6374 	.finish_reshape = raid5_finish_reshape,
6375 	.quiesce	= raid5_quiesce,
6376 	.takeover	= raid5_takeover,
6377 };
6378 
6379 static struct md_personality raid4_personality =
6380 {
6381 	.name		= "raid4",
6382 	.level		= 4,
6383 	.owner		= THIS_MODULE,
6384 	.make_request	= make_request,
6385 	.run		= run,
6386 	.stop		= stop,
6387 	.status		= status,
6388 	.error_handler	= error,
6389 	.hot_add_disk	= raid5_add_disk,
6390 	.hot_remove_disk= raid5_remove_disk,
6391 	.spare_active	= raid5_spare_active,
6392 	.sync_request	= sync_request,
6393 	.resize		= raid5_resize,
6394 	.size		= raid5_size,
6395 	.check_reshape	= raid5_check_reshape,
6396 	.start_reshape  = raid5_start_reshape,
6397 	.finish_reshape = raid5_finish_reshape,
6398 	.quiesce	= raid5_quiesce,
6399 	.takeover	= raid4_takeover,
6400 };
6401 
6402 static int __init raid5_init(void)
6403 {
6404 	register_md_personality(&raid6_personality);
6405 	register_md_personality(&raid5_personality);
6406 	register_md_personality(&raid4_personality);
6407 	return 0;
6408 }
6409 
6410 static void raid5_exit(void)
6411 {
6412 	unregister_md_personality(&raid6_personality);
6413 	unregister_md_personality(&raid5_personality);
6414 	unregister_md_personality(&raid4_personality);
6415 }
6416 
6417 module_init(raid5_init);
6418 module_exit(raid5_exit);
6419 MODULE_LICENSE("GPL");
6420 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
6421 MODULE_ALIAS("md-personality-4"); /* RAID5 */
6422 MODULE_ALIAS("md-raid5");
6423 MODULE_ALIAS("md-raid4");
6424 MODULE_ALIAS("md-level-5");
6425 MODULE_ALIAS("md-level-4");
6426 MODULE_ALIAS("md-personality-8"); /* RAID6 */
6427 MODULE_ALIAS("md-raid6");
6428 MODULE_ALIAS("md-level-6");
6429 
6430 /* This used to be two separate modules, they were: */
6431 MODULE_ALIAS("raid5");
6432 MODULE_ALIAS("raid6");
6433