xref: /openbmc/linux/drivers/md/raid5.c (revision 92a2c6b2)
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 <linux/nodemask.h>
57 #include <trace/events/block.h>
58 
59 #include "md.h"
60 #include "raid5.h"
61 #include "raid0.h"
62 #include "bitmap.h"
63 
64 #define cpu_to_group(cpu) cpu_to_node(cpu)
65 #define ANY_GROUP NUMA_NO_NODE
66 
67 static bool devices_handle_discard_safely = false;
68 module_param(devices_handle_discard_safely, bool, 0644);
69 MODULE_PARM_DESC(devices_handle_discard_safely,
70 		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
71 static struct workqueue_struct *raid5_wq;
72 /*
73  * Stripe cache
74  */
75 
76 #define NR_STRIPES		256
77 #define STRIPE_SIZE		PAGE_SIZE
78 #define STRIPE_SHIFT		(PAGE_SHIFT - 9)
79 #define STRIPE_SECTORS		(STRIPE_SIZE>>9)
80 #define	IO_THRESHOLD		1
81 #define BYPASS_THRESHOLD	1
82 #define NR_HASH			(PAGE_SIZE / sizeof(struct hlist_head))
83 #define HASH_MASK		(NR_HASH - 1)
84 #define MAX_STRIPE_BATCH	8
85 
86 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
87 {
88 	int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
89 	return &conf->stripe_hashtbl[hash];
90 }
91 
92 static inline int stripe_hash_locks_hash(sector_t sect)
93 {
94 	return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
95 }
96 
97 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
98 {
99 	spin_lock_irq(conf->hash_locks + hash);
100 	spin_lock(&conf->device_lock);
101 }
102 
103 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
104 {
105 	spin_unlock(&conf->device_lock);
106 	spin_unlock_irq(conf->hash_locks + hash);
107 }
108 
109 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
110 {
111 	int i;
112 	local_irq_disable();
113 	spin_lock(conf->hash_locks);
114 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
115 		spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
116 	spin_lock(&conf->device_lock);
117 }
118 
119 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
120 {
121 	int i;
122 	spin_unlock(&conf->device_lock);
123 	for (i = NR_STRIPE_HASH_LOCKS; i; i--)
124 		spin_unlock(conf->hash_locks + i - 1);
125 	local_irq_enable();
126 }
127 
128 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
129  * order without overlap.  There may be several bio's per stripe+device, and
130  * a bio could span several devices.
131  * When walking this list for a particular stripe+device, we must never proceed
132  * beyond a bio that extends past this device, as the next bio might no longer
133  * be valid.
134  * This function is used to determine the 'next' bio in the list, given the sector
135  * of the current stripe+device
136  */
137 static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
138 {
139 	int sectors = bio_sectors(bio);
140 	if (bio->bi_iter.bi_sector + sectors < sector + STRIPE_SECTORS)
141 		return bio->bi_next;
142 	else
143 		return NULL;
144 }
145 
146 /*
147  * We maintain a biased count of active stripes in the bottom 16 bits of
148  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
149  */
150 static inline int raid5_bi_processed_stripes(struct bio *bio)
151 {
152 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
153 	return (atomic_read(segments) >> 16) & 0xffff;
154 }
155 
156 static inline int raid5_dec_bi_active_stripes(struct bio *bio)
157 {
158 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
159 	return atomic_sub_return(1, segments) & 0xffff;
160 }
161 
162 static inline void raid5_inc_bi_active_stripes(struct bio *bio)
163 {
164 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
165 	atomic_inc(segments);
166 }
167 
168 static inline void raid5_set_bi_processed_stripes(struct bio *bio,
169 	unsigned int cnt)
170 {
171 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
172 	int old, new;
173 
174 	do {
175 		old = atomic_read(segments);
176 		new = (old & 0xffff) | (cnt << 16);
177 	} while (atomic_cmpxchg(segments, old, new) != old);
178 }
179 
180 static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
181 {
182 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
183 	atomic_set(segments, cnt);
184 }
185 
186 /* Find first data disk in a raid6 stripe */
187 static inline int raid6_d0(struct stripe_head *sh)
188 {
189 	if (sh->ddf_layout)
190 		/* ddf always start from first device */
191 		return 0;
192 	/* md starts just after Q block */
193 	if (sh->qd_idx == sh->disks - 1)
194 		return 0;
195 	else
196 		return sh->qd_idx + 1;
197 }
198 static inline int raid6_next_disk(int disk, int raid_disks)
199 {
200 	disk++;
201 	return (disk < raid_disks) ? disk : 0;
202 }
203 
204 /* When walking through the disks in a raid5, starting at raid6_d0,
205  * We need to map each disk to a 'slot', where the data disks are slot
206  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
207  * is raid_disks-1.  This help does that mapping.
208  */
209 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
210 			     int *count, int syndrome_disks)
211 {
212 	int slot = *count;
213 
214 	if (sh->ddf_layout)
215 		(*count)++;
216 	if (idx == sh->pd_idx)
217 		return syndrome_disks;
218 	if (idx == sh->qd_idx)
219 		return syndrome_disks + 1;
220 	if (!sh->ddf_layout)
221 		(*count)++;
222 	return slot;
223 }
224 
225 static void return_io(struct bio *return_bi)
226 {
227 	struct bio *bi = return_bi;
228 	while (bi) {
229 
230 		return_bi = bi->bi_next;
231 		bi->bi_next = NULL;
232 		bi->bi_iter.bi_size = 0;
233 		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
234 					 bi, 0);
235 		bio_endio(bi, 0);
236 		bi = return_bi;
237 	}
238 }
239 
240 static void print_raid5_conf (struct r5conf *conf);
241 
242 static int stripe_operations_active(struct stripe_head *sh)
243 {
244 	return sh->check_state || sh->reconstruct_state ||
245 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
246 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
247 }
248 
249 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
250 {
251 	struct r5conf *conf = sh->raid_conf;
252 	struct r5worker_group *group;
253 	int thread_cnt;
254 	int i, cpu = sh->cpu;
255 
256 	if (!cpu_online(cpu)) {
257 		cpu = cpumask_any(cpu_online_mask);
258 		sh->cpu = cpu;
259 	}
260 
261 	if (list_empty(&sh->lru)) {
262 		struct r5worker_group *group;
263 		group = conf->worker_groups + cpu_to_group(cpu);
264 		list_add_tail(&sh->lru, &group->handle_list);
265 		group->stripes_cnt++;
266 		sh->group = group;
267 	}
268 
269 	if (conf->worker_cnt_per_group == 0) {
270 		md_wakeup_thread(conf->mddev->thread);
271 		return;
272 	}
273 
274 	group = conf->worker_groups + cpu_to_group(sh->cpu);
275 
276 	group->workers[0].working = true;
277 	/* at least one worker should run to avoid race */
278 	queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
279 
280 	thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
281 	/* wakeup more workers */
282 	for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
283 		if (group->workers[i].working == false) {
284 			group->workers[i].working = true;
285 			queue_work_on(sh->cpu, raid5_wq,
286 				      &group->workers[i].work);
287 			thread_cnt--;
288 		}
289 	}
290 }
291 
292 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
293 			      struct list_head *temp_inactive_list)
294 {
295 	BUG_ON(!list_empty(&sh->lru));
296 	BUG_ON(atomic_read(&conf->active_stripes)==0);
297 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
298 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
299 		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
300 			list_add_tail(&sh->lru, &conf->delayed_list);
301 		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
302 			   sh->bm_seq - conf->seq_write > 0)
303 			list_add_tail(&sh->lru, &conf->bitmap_list);
304 		else {
305 			clear_bit(STRIPE_DELAYED, &sh->state);
306 			clear_bit(STRIPE_BIT_DELAY, &sh->state);
307 			if (conf->worker_cnt_per_group == 0) {
308 				list_add_tail(&sh->lru, &conf->handle_list);
309 			} else {
310 				raid5_wakeup_stripe_thread(sh);
311 				return;
312 			}
313 		}
314 		md_wakeup_thread(conf->mddev->thread);
315 	} else {
316 		BUG_ON(stripe_operations_active(sh));
317 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
318 			if (atomic_dec_return(&conf->preread_active_stripes)
319 			    < IO_THRESHOLD)
320 				md_wakeup_thread(conf->mddev->thread);
321 		atomic_dec(&conf->active_stripes);
322 		if (!test_bit(STRIPE_EXPANDING, &sh->state))
323 			list_add_tail(&sh->lru, temp_inactive_list);
324 	}
325 }
326 
327 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
328 			     struct list_head *temp_inactive_list)
329 {
330 	if (atomic_dec_and_test(&sh->count))
331 		do_release_stripe(conf, sh, temp_inactive_list);
332 }
333 
334 /*
335  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
336  *
337  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
338  * given time. Adding stripes only takes device lock, while deleting stripes
339  * only takes hash lock.
340  */
341 static void release_inactive_stripe_list(struct r5conf *conf,
342 					 struct list_head *temp_inactive_list,
343 					 int hash)
344 {
345 	int size;
346 	bool do_wakeup = false;
347 	unsigned long flags;
348 
349 	if (hash == NR_STRIPE_HASH_LOCKS) {
350 		size = NR_STRIPE_HASH_LOCKS;
351 		hash = NR_STRIPE_HASH_LOCKS - 1;
352 	} else
353 		size = 1;
354 	while (size) {
355 		struct list_head *list = &temp_inactive_list[size - 1];
356 
357 		/*
358 		 * We don't hold any lock here yet, get_active_stripe() might
359 		 * remove stripes from the list
360 		 */
361 		if (!list_empty_careful(list)) {
362 			spin_lock_irqsave(conf->hash_locks + hash, flags);
363 			if (list_empty(conf->inactive_list + hash) &&
364 			    !list_empty(list))
365 				atomic_dec(&conf->empty_inactive_list_nr);
366 			list_splice_tail_init(list, conf->inactive_list + hash);
367 			do_wakeup = true;
368 			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
369 		}
370 		size--;
371 		hash--;
372 	}
373 
374 	if (do_wakeup) {
375 		wake_up(&conf->wait_for_stripe);
376 		if (conf->retry_read_aligned)
377 			md_wakeup_thread(conf->mddev->thread);
378 	}
379 }
380 
381 /* should hold conf->device_lock already */
382 static int release_stripe_list(struct r5conf *conf,
383 			       struct list_head *temp_inactive_list)
384 {
385 	struct stripe_head *sh;
386 	int count = 0;
387 	struct llist_node *head;
388 
389 	head = llist_del_all(&conf->released_stripes);
390 	head = llist_reverse_order(head);
391 	while (head) {
392 		int hash;
393 
394 		sh = llist_entry(head, struct stripe_head, release_list);
395 		head = llist_next(head);
396 		/* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
397 		smp_mb();
398 		clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
399 		/*
400 		 * Don't worry the bit is set here, because if the bit is set
401 		 * again, the count is always > 1. This is true for
402 		 * STRIPE_ON_UNPLUG_LIST bit too.
403 		 */
404 		hash = sh->hash_lock_index;
405 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
406 		count++;
407 	}
408 
409 	return count;
410 }
411 
412 static void release_stripe(struct stripe_head *sh)
413 {
414 	struct r5conf *conf = sh->raid_conf;
415 	unsigned long flags;
416 	struct list_head list;
417 	int hash;
418 	bool wakeup;
419 
420 	/* Avoid release_list until the last reference.
421 	 */
422 	if (atomic_add_unless(&sh->count, -1, 1))
423 		return;
424 
425 	if (unlikely(!conf->mddev->thread) ||
426 		test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
427 		goto slow_path;
428 	wakeup = llist_add(&sh->release_list, &conf->released_stripes);
429 	if (wakeup)
430 		md_wakeup_thread(conf->mddev->thread);
431 	return;
432 slow_path:
433 	local_irq_save(flags);
434 	/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
435 	if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
436 		INIT_LIST_HEAD(&list);
437 		hash = sh->hash_lock_index;
438 		do_release_stripe(conf, sh, &list);
439 		spin_unlock(&conf->device_lock);
440 		release_inactive_stripe_list(conf, &list, hash);
441 	}
442 	local_irq_restore(flags);
443 }
444 
445 static inline void remove_hash(struct stripe_head *sh)
446 {
447 	pr_debug("remove_hash(), stripe %llu\n",
448 		(unsigned long long)sh->sector);
449 
450 	hlist_del_init(&sh->hash);
451 }
452 
453 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
454 {
455 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
456 
457 	pr_debug("insert_hash(), stripe %llu\n",
458 		(unsigned long long)sh->sector);
459 
460 	hlist_add_head(&sh->hash, hp);
461 }
462 
463 /* find an idle stripe, make sure it is unhashed, and return it. */
464 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
465 {
466 	struct stripe_head *sh = NULL;
467 	struct list_head *first;
468 
469 	if (list_empty(conf->inactive_list + hash))
470 		goto out;
471 	first = (conf->inactive_list + hash)->next;
472 	sh = list_entry(first, struct stripe_head, lru);
473 	list_del_init(first);
474 	remove_hash(sh);
475 	atomic_inc(&conf->active_stripes);
476 	BUG_ON(hash != sh->hash_lock_index);
477 	if (list_empty(conf->inactive_list + hash))
478 		atomic_inc(&conf->empty_inactive_list_nr);
479 out:
480 	return sh;
481 }
482 
483 static void shrink_buffers(struct stripe_head *sh)
484 {
485 	struct page *p;
486 	int i;
487 	int num = sh->raid_conf->pool_size;
488 
489 	for (i = 0; i < num ; i++) {
490 		WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
491 		p = sh->dev[i].page;
492 		if (!p)
493 			continue;
494 		sh->dev[i].page = NULL;
495 		put_page(p);
496 	}
497 }
498 
499 static int grow_buffers(struct stripe_head *sh)
500 {
501 	int i;
502 	int num = sh->raid_conf->pool_size;
503 
504 	for (i = 0; i < num; i++) {
505 		struct page *page;
506 
507 		if (!(page = alloc_page(GFP_KERNEL))) {
508 			return 1;
509 		}
510 		sh->dev[i].page = page;
511 		sh->dev[i].orig_page = page;
512 	}
513 	return 0;
514 }
515 
516 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
517 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
518 			    struct stripe_head *sh);
519 
520 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
521 {
522 	struct r5conf *conf = sh->raid_conf;
523 	int i, seq;
524 
525 	BUG_ON(atomic_read(&sh->count) != 0);
526 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
527 	BUG_ON(stripe_operations_active(sh));
528 
529 	pr_debug("init_stripe called, stripe %llu\n",
530 		(unsigned long long)sector);
531 retry:
532 	seq = read_seqcount_begin(&conf->gen_lock);
533 	sh->generation = conf->generation - previous;
534 	sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
535 	sh->sector = sector;
536 	stripe_set_idx(sector, conf, previous, sh);
537 	sh->state = 0;
538 
539 	for (i = sh->disks; i--; ) {
540 		struct r5dev *dev = &sh->dev[i];
541 
542 		if (dev->toread || dev->read || dev->towrite || dev->written ||
543 		    test_bit(R5_LOCKED, &dev->flags)) {
544 			printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
545 			       (unsigned long long)sh->sector, i, dev->toread,
546 			       dev->read, dev->towrite, dev->written,
547 			       test_bit(R5_LOCKED, &dev->flags));
548 			WARN_ON(1);
549 		}
550 		dev->flags = 0;
551 		raid5_build_block(sh, i, previous);
552 	}
553 	if (read_seqcount_retry(&conf->gen_lock, seq))
554 		goto retry;
555 	insert_hash(conf, sh);
556 	sh->cpu = smp_processor_id();
557 }
558 
559 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
560 					 short generation)
561 {
562 	struct stripe_head *sh;
563 
564 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
565 	hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
566 		if (sh->sector == sector && sh->generation == generation)
567 			return sh;
568 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
569 	return NULL;
570 }
571 
572 /*
573  * Need to check if array has failed when deciding whether to:
574  *  - start an array
575  *  - remove non-faulty devices
576  *  - add a spare
577  *  - allow a reshape
578  * This determination is simple when no reshape is happening.
579  * However if there is a reshape, we need to carefully check
580  * both the before and after sections.
581  * This is because some failed devices may only affect one
582  * of the two sections, and some non-in_sync devices may
583  * be insync in the section most affected by failed devices.
584  */
585 static int calc_degraded(struct r5conf *conf)
586 {
587 	int degraded, degraded2;
588 	int i;
589 
590 	rcu_read_lock();
591 	degraded = 0;
592 	for (i = 0; i < conf->previous_raid_disks; i++) {
593 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
594 		if (rdev && test_bit(Faulty, &rdev->flags))
595 			rdev = rcu_dereference(conf->disks[i].replacement);
596 		if (!rdev || test_bit(Faulty, &rdev->flags))
597 			degraded++;
598 		else if (test_bit(In_sync, &rdev->flags))
599 			;
600 		else
601 			/* not in-sync or faulty.
602 			 * If the reshape increases the number of devices,
603 			 * this is being recovered by the reshape, so
604 			 * this 'previous' section is not in_sync.
605 			 * If the number of devices is being reduced however,
606 			 * the device can only be part of the array if
607 			 * we are reverting a reshape, so this section will
608 			 * be in-sync.
609 			 */
610 			if (conf->raid_disks >= conf->previous_raid_disks)
611 				degraded++;
612 	}
613 	rcu_read_unlock();
614 	if (conf->raid_disks == conf->previous_raid_disks)
615 		return degraded;
616 	rcu_read_lock();
617 	degraded2 = 0;
618 	for (i = 0; i < conf->raid_disks; i++) {
619 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
620 		if (rdev && test_bit(Faulty, &rdev->flags))
621 			rdev = rcu_dereference(conf->disks[i].replacement);
622 		if (!rdev || test_bit(Faulty, &rdev->flags))
623 			degraded2++;
624 		else if (test_bit(In_sync, &rdev->flags))
625 			;
626 		else
627 			/* not in-sync or faulty.
628 			 * If reshape increases the number of devices, this
629 			 * section has already been recovered, else it
630 			 * almost certainly hasn't.
631 			 */
632 			if (conf->raid_disks <= conf->previous_raid_disks)
633 				degraded2++;
634 	}
635 	rcu_read_unlock();
636 	if (degraded2 > degraded)
637 		return degraded2;
638 	return degraded;
639 }
640 
641 static int has_failed(struct r5conf *conf)
642 {
643 	int degraded;
644 
645 	if (conf->mddev->reshape_position == MaxSector)
646 		return conf->mddev->degraded > conf->max_degraded;
647 
648 	degraded = calc_degraded(conf);
649 	if (degraded > conf->max_degraded)
650 		return 1;
651 	return 0;
652 }
653 
654 static struct stripe_head *
655 get_active_stripe(struct r5conf *conf, sector_t sector,
656 		  int previous, int noblock, int noquiesce)
657 {
658 	struct stripe_head *sh;
659 	int hash = stripe_hash_locks_hash(sector);
660 
661 	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
662 
663 	spin_lock_irq(conf->hash_locks + hash);
664 
665 	do {
666 		wait_event_lock_irq(conf->wait_for_stripe,
667 				    conf->quiesce == 0 || noquiesce,
668 				    *(conf->hash_locks + hash));
669 		sh = __find_stripe(conf, sector, conf->generation - previous);
670 		if (!sh) {
671 			if (!conf->inactive_blocked)
672 				sh = get_free_stripe(conf, hash);
673 			if (noblock && sh == NULL)
674 				break;
675 			if (!sh) {
676 				conf->inactive_blocked = 1;
677 				wait_event_lock_irq(
678 					conf->wait_for_stripe,
679 					!list_empty(conf->inactive_list + hash) &&
680 					(atomic_read(&conf->active_stripes)
681 					 < (conf->max_nr_stripes * 3 / 4)
682 					 || !conf->inactive_blocked),
683 					*(conf->hash_locks + hash));
684 				conf->inactive_blocked = 0;
685 			} else {
686 				init_stripe(sh, sector, previous);
687 				atomic_inc(&sh->count);
688 			}
689 		} else if (!atomic_inc_not_zero(&sh->count)) {
690 			spin_lock(&conf->device_lock);
691 			if (!atomic_read(&sh->count)) {
692 				if (!test_bit(STRIPE_HANDLE, &sh->state))
693 					atomic_inc(&conf->active_stripes);
694 				BUG_ON(list_empty(&sh->lru) &&
695 				       !test_bit(STRIPE_EXPANDING, &sh->state));
696 				list_del_init(&sh->lru);
697 				if (sh->group) {
698 					sh->group->stripes_cnt--;
699 					sh->group = NULL;
700 				}
701 			}
702 			atomic_inc(&sh->count);
703 			spin_unlock(&conf->device_lock);
704 		}
705 	} while (sh == NULL);
706 
707 	spin_unlock_irq(conf->hash_locks + hash);
708 	return sh;
709 }
710 
711 /* Determine if 'data_offset' or 'new_data_offset' should be used
712  * in this stripe_head.
713  */
714 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
715 {
716 	sector_t progress = conf->reshape_progress;
717 	/* Need a memory barrier to make sure we see the value
718 	 * of conf->generation, or ->data_offset that was set before
719 	 * reshape_progress was updated.
720 	 */
721 	smp_rmb();
722 	if (progress == MaxSector)
723 		return 0;
724 	if (sh->generation == conf->generation - 1)
725 		return 0;
726 	/* We are in a reshape, and this is a new-generation stripe,
727 	 * so use new_data_offset.
728 	 */
729 	return 1;
730 }
731 
732 static void
733 raid5_end_read_request(struct bio *bi, int error);
734 static void
735 raid5_end_write_request(struct bio *bi, int error);
736 
737 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
738 {
739 	struct r5conf *conf = sh->raid_conf;
740 	int i, disks = sh->disks;
741 
742 	might_sleep();
743 
744 	for (i = disks; i--; ) {
745 		int rw;
746 		int replace_only = 0;
747 		struct bio *bi, *rbi;
748 		struct md_rdev *rdev, *rrdev = NULL;
749 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
750 			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
751 				rw = WRITE_FUA;
752 			else
753 				rw = WRITE;
754 			if (test_bit(R5_Discard, &sh->dev[i].flags))
755 				rw |= REQ_DISCARD;
756 		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
757 			rw = READ;
758 		else if (test_and_clear_bit(R5_WantReplace,
759 					    &sh->dev[i].flags)) {
760 			rw = WRITE;
761 			replace_only = 1;
762 		} else
763 			continue;
764 		if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
765 			rw |= REQ_SYNC;
766 
767 		bi = &sh->dev[i].req;
768 		rbi = &sh->dev[i].rreq; /* For writing to replacement */
769 
770 		rcu_read_lock();
771 		rrdev = rcu_dereference(conf->disks[i].replacement);
772 		smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
773 		rdev = rcu_dereference(conf->disks[i].rdev);
774 		if (!rdev) {
775 			rdev = rrdev;
776 			rrdev = NULL;
777 		}
778 		if (rw & WRITE) {
779 			if (replace_only)
780 				rdev = NULL;
781 			if (rdev == rrdev)
782 				/* We raced and saw duplicates */
783 				rrdev = NULL;
784 		} else {
785 			if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
786 				rdev = rrdev;
787 			rrdev = NULL;
788 		}
789 
790 		if (rdev && test_bit(Faulty, &rdev->flags))
791 			rdev = NULL;
792 		if (rdev)
793 			atomic_inc(&rdev->nr_pending);
794 		if (rrdev && test_bit(Faulty, &rrdev->flags))
795 			rrdev = NULL;
796 		if (rrdev)
797 			atomic_inc(&rrdev->nr_pending);
798 		rcu_read_unlock();
799 
800 		/* We have already checked bad blocks for reads.  Now
801 		 * need to check for writes.  We never accept write errors
802 		 * on the replacement, so we don't to check rrdev.
803 		 */
804 		while ((rw & WRITE) && rdev &&
805 		       test_bit(WriteErrorSeen, &rdev->flags)) {
806 			sector_t first_bad;
807 			int bad_sectors;
808 			int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
809 					      &first_bad, &bad_sectors);
810 			if (!bad)
811 				break;
812 
813 			if (bad < 0) {
814 				set_bit(BlockedBadBlocks, &rdev->flags);
815 				if (!conf->mddev->external &&
816 				    conf->mddev->flags) {
817 					/* It is very unlikely, but we might
818 					 * still need to write out the
819 					 * bad block log - better give it
820 					 * a chance*/
821 					md_check_recovery(conf->mddev);
822 				}
823 				/*
824 				 * Because md_wait_for_blocked_rdev
825 				 * will dec nr_pending, we must
826 				 * increment it first.
827 				 */
828 				atomic_inc(&rdev->nr_pending);
829 				md_wait_for_blocked_rdev(rdev, conf->mddev);
830 			} else {
831 				/* Acknowledged bad block - skip the write */
832 				rdev_dec_pending(rdev, conf->mddev);
833 				rdev = NULL;
834 			}
835 		}
836 
837 		if (rdev) {
838 			if (s->syncing || s->expanding || s->expanded
839 			    || s->replacing)
840 				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
841 
842 			set_bit(STRIPE_IO_STARTED, &sh->state);
843 
844 			bio_reset(bi);
845 			bi->bi_bdev = rdev->bdev;
846 			bi->bi_rw = rw;
847 			bi->bi_end_io = (rw & WRITE)
848 				? raid5_end_write_request
849 				: raid5_end_read_request;
850 			bi->bi_private = sh;
851 
852 			pr_debug("%s: for %llu schedule op %ld on disc %d\n",
853 				__func__, (unsigned long long)sh->sector,
854 				bi->bi_rw, i);
855 			atomic_inc(&sh->count);
856 			if (use_new_offset(conf, sh))
857 				bi->bi_iter.bi_sector = (sh->sector
858 						 + rdev->new_data_offset);
859 			else
860 				bi->bi_iter.bi_sector = (sh->sector
861 						 + rdev->data_offset);
862 			if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
863 				bi->bi_rw |= REQ_NOMERGE;
864 
865 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
866 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
867 			sh->dev[i].vec.bv_page = sh->dev[i].page;
868 			bi->bi_vcnt = 1;
869 			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
870 			bi->bi_io_vec[0].bv_offset = 0;
871 			bi->bi_iter.bi_size = STRIPE_SIZE;
872 			/*
873 			 * If this is discard request, set bi_vcnt 0. We don't
874 			 * want to confuse SCSI because SCSI will replace payload
875 			 */
876 			if (rw & REQ_DISCARD)
877 				bi->bi_vcnt = 0;
878 			if (rrdev)
879 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
880 
881 			if (conf->mddev->gendisk)
882 				trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
883 						      bi, disk_devt(conf->mddev->gendisk),
884 						      sh->dev[i].sector);
885 			generic_make_request(bi);
886 		}
887 		if (rrdev) {
888 			if (s->syncing || s->expanding || s->expanded
889 			    || s->replacing)
890 				md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
891 
892 			set_bit(STRIPE_IO_STARTED, &sh->state);
893 
894 			bio_reset(rbi);
895 			rbi->bi_bdev = rrdev->bdev;
896 			rbi->bi_rw = rw;
897 			BUG_ON(!(rw & WRITE));
898 			rbi->bi_end_io = raid5_end_write_request;
899 			rbi->bi_private = sh;
900 
901 			pr_debug("%s: for %llu schedule op %ld on "
902 				 "replacement disc %d\n",
903 				__func__, (unsigned long long)sh->sector,
904 				rbi->bi_rw, i);
905 			atomic_inc(&sh->count);
906 			if (use_new_offset(conf, sh))
907 				rbi->bi_iter.bi_sector = (sh->sector
908 						  + rrdev->new_data_offset);
909 			else
910 				rbi->bi_iter.bi_sector = (sh->sector
911 						  + rrdev->data_offset);
912 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
913 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
914 			sh->dev[i].rvec.bv_page = sh->dev[i].page;
915 			rbi->bi_vcnt = 1;
916 			rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
917 			rbi->bi_io_vec[0].bv_offset = 0;
918 			rbi->bi_iter.bi_size = STRIPE_SIZE;
919 			/*
920 			 * If this is discard request, set bi_vcnt 0. We don't
921 			 * want to confuse SCSI because SCSI will replace payload
922 			 */
923 			if (rw & REQ_DISCARD)
924 				rbi->bi_vcnt = 0;
925 			if (conf->mddev->gendisk)
926 				trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
927 						      rbi, disk_devt(conf->mddev->gendisk),
928 						      sh->dev[i].sector);
929 			generic_make_request(rbi);
930 		}
931 		if (!rdev && !rrdev) {
932 			if (rw & WRITE)
933 				set_bit(STRIPE_DEGRADED, &sh->state);
934 			pr_debug("skip op %ld on disc %d for sector %llu\n",
935 				bi->bi_rw, i, (unsigned long long)sh->sector);
936 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
937 			set_bit(STRIPE_HANDLE, &sh->state);
938 		}
939 	}
940 }
941 
942 static struct dma_async_tx_descriptor *
943 async_copy_data(int frombio, struct bio *bio, struct page **page,
944 	sector_t sector, struct dma_async_tx_descriptor *tx,
945 	struct stripe_head *sh)
946 {
947 	struct bio_vec bvl;
948 	struct bvec_iter iter;
949 	struct page *bio_page;
950 	int page_offset;
951 	struct async_submit_ctl submit;
952 	enum async_tx_flags flags = 0;
953 
954 	if (bio->bi_iter.bi_sector >= sector)
955 		page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
956 	else
957 		page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
958 
959 	if (frombio)
960 		flags |= ASYNC_TX_FENCE;
961 	init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
962 
963 	bio_for_each_segment(bvl, bio, iter) {
964 		int len = bvl.bv_len;
965 		int clen;
966 		int b_offset = 0;
967 
968 		if (page_offset < 0) {
969 			b_offset = -page_offset;
970 			page_offset += b_offset;
971 			len -= b_offset;
972 		}
973 
974 		if (len > 0 && page_offset + len > STRIPE_SIZE)
975 			clen = STRIPE_SIZE - page_offset;
976 		else
977 			clen = len;
978 
979 		if (clen > 0) {
980 			b_offset += bvl.bv_offset;
981 			bio_page = bvl.bv_page;
982 			if (frombio) {
983 				if (sh->raid_conf->skip_copy &&
984 				    b_offset == 0 && page_offset == 0 &&
985 				    clen == STRIPE_SIZE)
986 					*page = bio_page;
987 				else
988 					tx = async_memcpy(*page, bio_page, page_offset,
989 						  b_offset, clen, &submit);
990 			} else
991 				tx = async_memcpy(bio_page, *page, b_offset,
992 						  page_offset, clen, &submit);
993 		}
994 		/* chain the operations */
995 		submit.depend_tx = tx;
996 
997 		if (clen < len) /* hit end of page */
998 			break;
999 		page_offset +=  len;
1000 	}
1001 
1002 	return tx;
1003 }
1004 
1005 static void ops_complete_biofill(void *stripe_head_ref)
1006 {
1007 	struct stripe_head *sh = stripe_head_ref;
1008 	struct bio *return_bi = NULL;
1009 	int i;
1010 
1011 	pr_debug("%s: stripe %llu\n", __func__,
1012 		(unsigned long long)sh->sector);
1013 
1014 	/* clear completed biofills */
1015 	for (i = sh->disks; i--; ) {
1016 		struct r5dev *dev = &sh->dev[i];
1017 
1018 		/* acknowledge completion of a biofill operation */
1019 		/* and check if we need to reply to a read request,
1020 		 * new R5_Wantfill requests are held off until
1021 		 * !STRIPE_BIOFILL_RUN
1022 		 */
1023 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1024 			struct bio *rbi, *rbi2;
1025 
1026 			BUG_ON(!dev->read);
1027 			rbi = dev->read;
1028 			dev->read = NULL;
1029 			while (rbi && rbi->bi_iter.bi_sector <
1030 				dev->sector + STRIPE_SECTORS) {
1031 				rbi2 = r5_next_bio(rbi, dev->sector);
1032 				if (!raid5_dec_bi_active_stripes(rbi)) {
1033 					rbi->bi_next = return_bi;
1034 					return_bi = rbi;
1035 				}
1036 				rbi = rbi2;
1037 			}
1038 		}
1039 	}
1040 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1041 
1042 	return_io(return_bi);
1043 
1044 	set_bit(STRIPE_HANDLE, &sh->state);
1045 	release_stripe(sh);
1046 }
1047 
1048 static void ops_run_biofill(struct stripe_head *sh)
1049 {
1050 	struct dma_async_tx_descriptor *tx = NULL;
1051 	struct async_submit_ctl submit;
1052 	int i;
1053 
1054 	pr_debug("%s: stripe %llu\n", __func__,
1055 		(unsigned long long)sh->sector);
1056 
1057 	for (i = sh->disks; i--; ) {
1058 		struct r5dev *dev = &sh->dev[i];
1059 		if (test_bit(R5_Wantfill, &dev->flags)) {
1060 			struct bio *rbi;
1061 			spin_lock_irq(&sh->stripe_lock);
1062 			dev->read = rbi = dev->toread;
1063 			dev->toread = NULL;
1064 			spin_unlock_irq(&sh->stripe_lock);
1065 			while (rbi && rbi->bi_iter.bi_sector <
1066 				dev->sector + STRIPE_SECTORS) {
1067 				tx = async_copy_data(0, rbi, &dev->page,
1068 					dev->sector, tx, sh);
1069 				rbi = r5_next_bio(rbi, dev->sector);
1070 			}
1071 		}
1072 	}
1073 
1074 	atomic_inc(&sh->count);
1075 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1076 	async_trigger_callback(&submit);
1077 }
1078 
1079 static void mark_target_uptodate(struct stripe_head *sh, int target)
1080 {
1081 	struct r5dev *tgt;
1082 
1083 	if (target < 0)
1084 		return;
1085 
1086 	tgt = &sh->dev[target];
1087 	set_bit(R5_UPTODATE, &tgt->flags);
1088 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1089 	clear_bit(R5_Wantcompute, &tgt->flags);
1090 }
1091 
1092 static void ops_complete_compute(void *stripe_head_ref)
1093 {
1094 	struct stripe_head *sh = stripe_head_ref;
1095 
1096 	pr_debug("%s: stripe %llu\n", __func__,
1097 		(unsigned long long)sh->sector);
1098 
1099 	/* mark the computed target(s) as uptodate */
1100 	mark_target_uptodate(sh, sh->ops.target);
1101 	mark_target_uptodate(sh, sh->ops.target2);
1102 
1103 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1104 	if (sh->check_state == check_state_compute_run)
1105 		sh->check_state = check_state_compute_result;
1106 	set_bit(STRIPE_HANDLE, &sh->state);
1107 	release_stripe(sh);
1108 }
1109 
1110 /* return a pointer to the address conversion region of the scribble buffer */
1111 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1112 				 struct raid5_percpu *percpu)
1113 {
1114 	return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
1115 }
1116 
1117 static struct dma_async_tx_descriptor *
1118 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1119 {
1120 	int disks = sh->disks;
1121 	struct page **xor_srcs = percpu->scribble;
1122 	int target = sh->ops.target;
1123 	struct r5dev *tgt = &sh->dev[target];
1124 	struct page *xor_dest = tgt->page;
1125 	int count = 0;
1126 	struct dma_async_tx_descriptor *tx;
1127 	struct async_submit_ctl submit;
1128 	int i;
1129 
1130 	pr_debug("%s: stripe %llu block: %d\n",
1131 		__func__, (unsigned long long)sh->sector, target);
1132 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1133 
1134 	for (i = disks; i--; )
1135 		if (i != target)
1136 			xor_srcs[count++] = sh->dev[i].page;
1137 
1138 	atomic_inc(&sh->count);
1139 
1140 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1141 			  ops_complete_compute, sh, to_addr_conv(sh, percpu));
1142 	if (unlikely(count == 1))
1143 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1144 	else
1145 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1146 
1147 	return tx;
1148 }
1149 
1150 /* set_syndrome_sources - populate source buffers for gen_syndrome
1151  * @srcs - (struct page *) array of size sh->disks
1152  * @sh - stripe_head to parse
1153  *
1154  * Populates srcs in proper layout order for the stripe and returns the
1155  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1156  * destination buffer is recorded in srcs[count] and the Q destination
1157  * is recorded in srcs[count+1]].
1158  */
1159 static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
1160 {
1161 	int disks = sh->disks;
1162 	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1163 	int d0_idx = raid6_d0(sh);
1164 	int count;
1165 	int i;
1166 
1167 	for (i = 0; i < disks; i++)
1168 		srcs[i] = NULL;
1169 
1170 	count = 0;
1171 	i = d0_idx;
1172 	do {
1173 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1174 
1175 		srcs[slot] = sh->dev[i].page;
1176 		i = raid6_next_disk(i, disks);
1177 	} while (i != d0_idx);
1178 
1179 	return syndrome_disks;
1180 }
1181 
1182 static struct dma_async_tx_descriptor *
1183 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1184 {
1185 	int disks = sh->disks;
1186 	struct page **blocks = percpu->scribble;
1187 	int target;
1188 	int qd_idx = sh->qd_idx;
1189 	struct dma_async_tx_descriptor *tx;
1190 	struct async_submit_ctl submit;
1191 	struct r5dev *tgt;
1192 	struct page *dest;
1193 	int i;
1194 	int count;
1195 
1196 	if (sh->ops.target < 0)
1197 		target = sh->ops.target2;
1198 	else if (sh->ops.target2 < 0)
1199 		target = sh->ops.target;
1200 	else
1201 		/* we should only have one valid target */
1202 		BUG();
1203 	BUG_ON(target < 0);
1204 	pr_debug("%s: stripe %llu block: %d\n",
1205 		__func__, (unsigned long long)sh->sector, target);
1206 
1207 	tgt = &sh->dev[target];
1208 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1209 	dest = tgt->page;
1210 
1211 	atomic_inc(&sh->count);
1212 
1213 	if (target == qd_idx) {
1214 		count = set_syndrome_sources(blocks, sh);
1215 		blocks[count] = NULL; /* regenerating p is not necessary */
1216 		BUG_ON(blocks[count+1] != dest); /* q should already be set */
1217 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1218 				  ops_complete_compute, sh,
1219 				  to_addr_conv(sh, percpu));
1220 		tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1221 	} else {
1222 		/* Compute any data- or p-drive using XOR */
1223 		count = 0;
1224 		for (i = disks; i-- ; ) {
1225 			if (i == target || i == qd_idx)
1226 				continue;
1227 			blocks[count++] = sh->dev[i].page;
1228 		}
1229 
1230 		init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1231 				  NULL, ops_complete_compute, sh,
1232 				  to_addr_conv(sh, percpu));
1233 		tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1234 	}
1235 
1236 	return tx;
1237 }
1238 
1239 static struct dma_async_tx_descriptor *
1240 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1241 {
1242 	int i, count, disks = sh->disks;
1243 	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1244 	int d0_idx = raid6_d0(sh);
1245 	int faila = -1, failb = -1;
1246 	int target = sh->ops.target;
1247 	int target2 = sh->ops.target2;
1248 	struct r5dev *tgt = &sh->dev[target];
1249 	struct r5dev *tgt2 = &sh->dev[target2];
1250 	struct dma_async_tx_descriptor *tx;
1251 	struct page **blocks = percpu->scribble;
1252 	struct async_submit_ctl submit;
1253 
1254 	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1255 		 __func__, (unsigned long long)sh->sector, target, target2);
1256 	BUG_ON(target < 0 || target2 < 0);
1257 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1258 	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1259 
1260 	/* we need to open-code set_syndrome_sources to handle the
1261 	 * slot number conversion for 'faila' and 'failb'
1262 	 */
1263 	for (i = 0; i < disks ; i++)
1264 		blocks[i] = NULL;
1265 	count = 0;
1266 	i = d0_idx;
1267 	do {
1268 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1269 
1270 		blocks[slot] = sh->dev[i].page;
1271 
1272 		if (i == target)
1273 			faila = slot;
1274 		if (i == target2)
1275 			failb = slot;
1276 		i = raid6_next_disk(i, disks);
1277 	} while (i != d0_idx);
1278 
1279 	BUG_ON(faila == failb);
1280 	if (failb < faila)
1281 		swap(faila, failb);
1282 	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1283 		 __func__, (unsigned long long)sh->sector, faila, failb);
1284 
1285 	atomic_inc(&sh->count);
1286 
1287 	if (failb == syndrome_disks+1) {
1288 		/* Q disk is one of the missing disks */
1289 		if (faila == syndrome_disks) {
1290 			/* Missing P+Q, just recompute */
1291 			init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1292 					  ops_complete_compute, sh,
1293 					  to_addr_conv(sh, percpu));
1294 			return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1295 						  STRIPE_SIZE, &submit);
1296 		} else {
1297 			struct page *dest;
1298 			int data_target;
1299 			int qd_idx = sh->qd_idx;
1300 
1301 			/* Missing D+Q: recompute D from P, then recompute Q */
1302 			if (target == qd_idx)
1303 				data_target = target2;
1304 			else
1305 				data_target = target;
1306 
1307 			count = 0;
1308 			for (i = disks; i-- ; ) {
1309 				if (i == data_target || i == qd_idx)
1310 					continue;
1311 				blocks[count++] = sh->dev[i].page;
1312 			}
1313 			dest = sh->dev[data_target].page;
1314 			init_async_submit(&submit,
1315 					  ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1316 					  NULL, NULL, NULL,
1317 					  to_addr_conv(sh, percpu));
1318 			tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1319 				       &submit);
1320 
1321 			count = set_syndrome_sources(blocks, sh);
1322 			init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1323 					  ops_complete_compute, sh,
1324 					  to_addr_conv(sh, percpu));
1325 			return async_gen_syndrome(blocks, 0, count+2,
1326 						  STRIPE_SIZE, &submit);
1327 		}
1328 	} else {
1329 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1330 				  ops_complete_compute, sh,
1331 				  to_addr_conv(sh, percpu));
1332 		if (failb == syndrome_disks) {
1333 			/* We're missing D+P. */
1334 			return async_raid6_datap_recov(syndrome_disks+2,
1335 						       STRIPE_SIZE, faila,
1336 						       blocks, &submit);
1337 		} else {
1338 			/* We're missing D+D. */
1339 			return async_raid6_2data_recov(syndrome_disks+2,
1340 						       STRIPE_SIZE, faila, failb,
1341 						       blocks, &submit);
1342 		}
1343 	}
1344 }
1345 
1346 static void ops_complete_prexor(void *stripe_head_ref)
1347 {
1348 	struct stripe_head *sh = stripe_head_ref;
1349 
1350 	pr_debug("%s: stripe %llu\n", __func__,
1351 		(unsigned long long)sh->sector);
1352 }
1353 
1354 static struct dma_async_tx_descriptor *
1355 ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1356 	       struct dma_async_tx_descriptor *tx)
1357 {
1358 	int disks = sh->disks;
1359 	struct page **xor_srcs = percpu->scribble;
1360 	int count = 0, pd_idx = sh->pd_idx, i;
1361 	struct async_submit_ctl submit;
1362 
1363 	/* existing parity data subtracted */
1364 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1365 
1366 	pr_debug("%s: stripe %llu\n", __func__,
1367 		(unsigned long long)sh->sector);
1368 
1369 	for (i = disks; i--; ) {
1370 		struct r5dev *dev = &sh->dev[i];
1371 		/* Only process blocks that are known to be uptodate */
1372 		if (test_bit(R5_Wantdrain, &dev->flags))
1373 			xor_srcs[count++] = dev->page;
1374 	}
1375 
1376 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1377 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1378 	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1379 
1380 	return tx;
1381 }
1382 
1383 static struct dma_async_tx_descriptor *
1384 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1385 {
1386 	int disks = sh->disks;
1387 	int i;
1388 
1389 	pr_debug("%s: stripe %llu\n", __func__,
1390 		(unsigned long long)sh->sector);
1391 
1392 	for (i = disks; i--; ) {
1393 		struct r5dev *dev = &sh->dev[i];
1394 		struct bio *chosen;
1395 
1396 		if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1397 			struct bio *wbi;
1398 
1399 			spin_lock_irq(&sh->stripe_lock);
1400 			chosen = dev->towrite;
1401 			dev->towrite = NULL;
1402 			BUG_ON(dev->written);
1403 			wbi = dev->written = chosen;
1404 			spin_unlock_irq(&sh->stripe_lock);
1405 			WARN_ON(dev->page != dev->orig_page);
1406 
1407 			while (wbi && wbi->bi_iter.bi_sector <
1408 				dev->sector + STRIPE_SECTORS) {
1409 				if (wbi->bi_rw & REQ_FUA)
1410 					set_bit(R5_WantFUA, &dev->flags);
1411 				if (wbi->bi_rw & REQ_SYNC)
1412 					set_bit(R5_SyncIO, &dev->flags);
1413 				if (wbi->bi_rw & REQ_DISCARD)
1414 					set_bit(R5_Discard, &dev->flags);
1415 				else {
1416 					tx = async_copy_data(1, wbi, &dev->page,
1417 						dev->sector, tx, sh);
1418 					if (dev->page != dev->orig_page) {
1419 						set_bit(R5_SkipCopy, &dev->flags);
1420 						clear_bit(R5_UPTODATE, &dev->flags);
1421 						clear_bit(R5_OVERWRITE, &dev->flags);
1422 					}
1423 				}
1424 				wbi = r5_next_bio(wbi, dev->sector);
1425 			}
1426 		}
1427 	}
1428 
1429 	return tx;
1430 }
1431 
1432 static void ops_complete_reconstruct(void *stripe_head_ref)
1433 {
1434 	struct stripe_head *sh = stripe_head_ref;
1435 	int disks = sh->disks;
1436 	int pd_idx = sh->pd_idx;
1437 	int qd_idx = sh->qd_idx;
1438 	int i;
1439 	bool fua = false, sync = false, discard = false;
1440 
1441 	pr_debug("%s: stripe %llu\n", __func__,
1442 		(unsigned long long)sh->sector);
1443 
1444 	for (i = disks; i--; ) {
1445 		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1446 		sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1447 		discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1448 	}
1449 
1450 	for (i = disks; i--; ) {
1451 		struct r5dev *dev = &sh->dev[i];
1452 
1453 		if (dev->written || i == pd_idx || i == qd_idx) {
1454 			if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1455 				set_bit(R5_UPTODATE, &dev->flags);
1456 			if (fua)
1457 				set_bit(R5_WantFUA, &dev->flags);
1458 			if (sync)
1459 				set_bit(R5_SyncIO, &dev->flags);
1460 		}
1461 	}
1462 
1463 	if (sh->reconstruct_state == reconstruct_state_drain_run)
1464 		sh->reconstruct_state = reconstruct_state_drain_result;
1465 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1466 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1467 	else {
1468 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1469 		sh->reconstruct_state = reconstruct_state_result;
1470 	}
1471 
1472 	set_bit(STRIPE_HANDLE, &sh->state);
1473 	release_stripe(sh);
1474 }
1475 
1476 static void
1477 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1478 		     struct dma_async_tx_descriptor *tx)
1479 {
1480 	int disks = sh->disks;
1481 	struct page **xor_srcs = percpu->scribble;
1482 	struct async_submit_ctl submit;
1483 	int count = 0, pd_idx = sh->pd_idx, i;
1484 	struct page *xor_dest;
1485 	int prexor = 0;
1486 	unsigned long flags;
1487 
1488 	pr_debug("%s: stripe %llu\n", __func__,
1489 		(unsigned long long)sh->sector);
1490 
1491 	for (i = 0; i < sh->disks; i++) {
1492 		if (pd_idx == i)
1493 			continue;
1494 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1495 			break;
1496 	}
1497 	if (i >= sh->disks) {
1498 		atomic_inc(&sh->count);
1499 		set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1500 		ops_complete_reconstruct(sh);
1501 		return;
1502 	}
1503 	/* check if prexor is active which means only process blocks
1504 	 * that are part of a read-modify-write (written)
1505 	 */
1506 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1507 		prexor = 1;
1508 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1509 		for (i = disks; i--; ) {
1510 			struct r5dev *dev = &sh->dev[i];
1511 			if (dev->written)
1512 				xor_srcs[count++] = dev->page;
1513 		}
1514 	} else {
1515 		xor_dest = sh->dev[pd_idx].page;
1516 		for (i = disks; i--; ) {
1517 			struct r5dev *dev = &sh->dev[i];
1518 			if (i != pd_idx)
1519 				xor_srcs[count++] = dev->page;
1520 		}
1521 	}
1522 
1523 	/* 1/ if we prexor'd then the dest is reused as a source
1524 	 * 2/ if we did not prexor then we are redoing the parity
1525 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1526 	 * for the synchronous xor case
1527 	 */
1528 	flags = ASYNC_TX_ACK |
1529 		(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1530 
1531 	atomic_inc(&sh->count);
1532 
1533 	init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1534 			  to_addr_conv(sh, percpu));
1535 	if (unlikely(count == 1))
1536 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1537 	else
1538 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1539 }
1540 
1541 static void
1542 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1543 		     struct dma_async_tx_descriptor *tx)
1544 {
1545 	struct async_submit_ctl submit;
1546 	struct page **blocks = percpu->scribble;
1547 	int count, i;
1548 
1549 	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1550 
1551 	for (i = 0; i < sh->disks; i++) {
1552 		if (sh->pd_idx == i || sh->qd_idx == i)
1553 			continue;
1554 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1555 			break;
1556 	}
1557 	if (i >= sh->disks) {
1558 		atomic_inc(&sh->count);
1559 		set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1560 		set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1561 		ops_complete_reconstruct(sh);
1562 		return;
1563 	}
1564 
1565 	count = set_syndrome_sources(blocks, sh);
1566 
1567 	atomic_inc(&sh->count);
1568 
1569 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1570 			  sh, to_addr_conv(sh, percpu));
1571 	async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1572 }
1573 
1574 static void ops_complete_check(void *stripe_head_ref)
1575 {
1576 	struct stripe_head *sh = stripe_head_ref;
1577 
1578 	pr_debug("%s: stripe %llu\n", __func__,
1579 		(unsigned long long)sh->sector);
1580 
1581 	sh->check_state = check_state_check_result;
1582 	set_bit(STRIPE_HANDLE, &sh->state);
1583 	release_stripe(sh);
1584 }
1585 
1586 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1587 {
1588 	int disks = sh->disks;
1589 	int pd_idx = sh->pd_idx;
1590 	int qd_idx = sh->qd_idx;
1591 	struct page *xor_dest;
1592 	struct page **xor_srcs = percpu->scribble;
1593 	struct dma_async_tx_descriptor *tx;
1594 	struct async_submit_ctl submit;
1595 	int count;
1596 	int i;
1597 
1598 	pr_debug("%s: stripe %llu\n", __func__,
1599 		(unsigned long long)sh->sector);
1600 
1601 	count = 0;
1602 	xor_dest = sh->dev[pd_idx].page;
1603 	xor_srcs[count++] = xor_dest;
1604 	for (i = disks; i--; ) {
1605 		if (i == pd_idx || i == qd_idx)
1606 			continue;
1607 		xor_srcs[count++] = sh->dev[i].page;
1608 	}
1609 
1610 	init_async_submit(&submit, 0, NULL, NULL, NULL,
1611 			  to_addr_conv(sh, percpu));
1612 	tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1613 			   &sh->ops.zero_sum_result, &submit);
1614 
1615 	atomic_inc(&sh->count);
1616 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1617 	tx = async_trigger_callback(&submit);
1618 }
1619 
1620 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1621 {
1622 	struct page **srcs = percpu->scribble;
1623 	struct async_submit_ctl submit;
1624 	int count;
1625 
1626 	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1627 		(unsigned long long)sh->sector, checkp);
1628 
1629 	count = set_syndrome_sources(srcs, sh);
1630 	if (!checkp)
1631 		srcs[count] = NULL;
1632 
1633 	atomic_inc(&sh->count);
1634 	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1635 			  sh, to_addr_conv(sh, percpu));
1636 	async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1637 			   &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1638 }
1639 
1640 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1641 {
1642 	int overlap_clear = 0, i, disks = sh->disks;
1643 	struct dma_async_tx_descriptor *tx = NULL;
1644 	struct r5conf *conf = sh->raid_conf;
1645 	int level = conf->level;
1646 	struct raid5_percpu *percpu;
1647 	unsigned long cpu;
1648 
1649 	cpu = get_cpu();
1650 	percpu = per_cpu_ptr(conf->percpu, cpu);
1651 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1652 		ops_run_biofill(sh);
1653 		overlap_clear++;
1654 	}
1655 
1656 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1657 		if (level < 6)
1658 			tx = ops_run_compute5(sh, percpu);
1659 		else {
1660 			if (sh->ops.target2 < 0 || sh->ops.target < 0)
1661 				tx = ops_run_compute6_1(sh, percpu);
1662 			else
1663 				tx = ops_run_compute6_2(sh, percpu);
1664 		}
1665 		/* terminate the chain if reconstruct is not set to be run */
1666 		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1667 			async_tx_ack(tx);
1668 	}
1669 
1670 	if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1671 		tx = ops_run_prexor(sh, percpu, tx);
1672 
1673 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1674 		tx = ops_run_biodrain(sh, tx);
1675 		overlap_clear++;
1676 	}
1677 
1678 	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1679 		if (level < 6)
1680 			ops_run_reconstruct5(sh, percpu, tx);
1681 		else
1682 			ops_run_reconstruct6(sh, percpu, tx);
1683 	}
1684 
1685 	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1686 		if (sh->check_state == check_state_run)
1687 			ops_run_check_p(sh, percpu);
1688 		else if (sh->check_state == check_state_run_q)
1689 			ops_run_check_pq(sh, percpu, 0);
1690 		else if (sh->check_state == check_state_run_pq)
1691 			ops_run_check_pq(sh, percpu, 1);
1692 		else
1693 			BUG();
1694 	}
1695 
1696 	if (overlap_clear)
1697 		for (i = disks; i--; ) {
1698 			struct r5dev *dev = &sh->dev[i];
1699 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
1700 				wake_up(&sh->raid_conf->wait_for_overlap);
1701 		}
1702 	put_cpu();
1703 }
1704 
1705 static int grow_one_stripe(struct r5conf *conf, int hash)
1706 {
1707 	struct stripe_head *sh;
1708 	sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1709 	if (!sh)
1710 		return 0;
1711 
1712 	sh->raid_conf = conf;
1713 
1714 	spin_lock_init(&sh->stripe_lock);
1715 
1716 	if (grow_buffers(sh)) {
1717 		shrink_buffers(sh);
1718 		kmem_cache_free(conf->slab_cache, sh);
1719 		return 0;
1720 	}
1721 	sh->hash_lock_index = hash;
1722 	/* we just created an active stripe so... */
1723 	atomic_set(&sh->count, 1);
1724 	atomic_inc(&conf->active_stripes);
1725 	INIT_LIST_HEAD(&sh->lru);
1726 	release_stripe(sh);
1727 	return 1;
1728 }
1729 
1730 static int grow_stripes(struct r5conf *conf, int num)
1731 {
1732 	struct kmem_cache *sc;
1733 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
1734 	int hash;
1735 
1736 	if (conf->mddev->gendisk)
1737 		sprintf(conf->cache_name[0],
1738 			"raid%d-%s", conf->level, mdname(conf->mddev));
1739 	else
1740 		sprintf(conf->cache_name[0],
1741 			"raid%d-%p", conf->level, conf->mddev);
1742 	sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1743 
1744 	conf->active_name = 0;
1745 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
1746 			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1747 			       0, 0, NULL);
1748 	if (!sc)
1749 		return 1;
1750 	conf->slab_cache = sc;
1751 	conf->pool_size = devs;
1752 	hash = conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
1753 	while (num--) {
1754 		if (!grow_one_stripe(conf, hash))
1755 			return 1;
1756 		conf->max_nr_stripes++;
1757 		hash = (hash + 1) % NR_STRIPE_HASH_LOCKS;
1758 	}
1759 	return 0;
1760 }
1761 
1762 /**
1763  * scribble_len - return the required size of the scribble region
1764  * @num - total number of disks in the array
1765  *
1766  * The size must be enough to contain:
1767  * 1/ a struct page pointer for each device in the array +2
1768  * 2/ room to convert each entry in (1) to its corresponding dma
1769  *    (dma_map_page()) or page (page_address()) address.
1770  *
1771  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1772  * calculate over all devices (not just the data blocks), using zeros in place
1773  * of the P and Q blocks.
1774  */
1775 static size_t scribble_len(int num)
1776 {
1777 	size_t len;
1778 
1779 	len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1780 
1781 	return len;
1782 }
1783 
1784 static int resize_stripes(struct r5conf *conf, int newsize)
1785 {
1786 	/* Make all the stripes able to hold 'newsize' devices.
1787 	 * New slots in each stripe get 'page' set to a new page.
1788 	 *
1789 	 * This happens in stages:
1790 	 * 1/ create a new kmem_cache and allocate the required number of
1791 	 *    stripe_heads.
1792 	 * 2/ gather all the old stripe_heads and transfer the pages across
1793 	 *    to the new stripe_heads.  This will have the side effect of
1794 	 *    freezing the array as once all stripe_heads have been collected,
1795 	 *    no IO will be possible.  Old stripe heads are freed once their
1796 	 *    pages have been transferred over, and the old kmem_cache is
1797 	 *    freed when all stripes are done.
1798 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1799 	 *    we simple return a failre status - no need to clean anything up.
1800 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
1801 	 *    If this fails, we don't bother trying the shrink the
1802 	 *    stripe_heads down again, we just leave them as they are.
1803 	 *    As each stripe_head is processed the new one is released into
1804 	 *    active service.
1805 	 *
1806 	 * Once step2 is started, we cannot afford to wait for a write,
1807 	 * so we use GFP_NOIO allocations.
1808 	 */
1809 	struct stripe_head *osh, *nsh;
1810 	LIST_HEAD(newstripes);
1811 	struct disk_info *ndisks;
1812 	unsigned long cpu;
1813 	int err;
1814 	struct kmem_cache *sc;
1815 	int i;
1816 	int hash, cnt;
1817 
1818 	if (newsize <= conf->pool_size)
1819 		return 0; /* never bother to shrink */
1820 
1821 	err = md_allow_write(conf->mddev);
1822 	if (err)
1823 		return err;
1824 
1825 	/* Step 1 */
1826 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1827 			       sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1828 			       0, 0, NULL);
1829 	if (!sc)
1830 		return -ENOMEM;
1831 
1832 	for (i = conf->max_nr_stripes; i; i--) {
1833 		nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1834 		if (!nsh)
1835 			break;
1836 
1837 		nsh->raid_conf = conf;
1838 		spin_lock_init(&nsh->stripe_lock);
1839 
1840 		list_add(&nsh->lru, &newstripes);
1841 	}
1842 	if (i) {
1843 		/* didn't get enough, give up */
1844 		while (!list_empty(&newstripes)) {
1845 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
1846 			list_del(&nsh->lru);
1847 			kmem_cache_free(sc, nsh);
1848 		}
1849 		kmem_cache_destroy(sc);
1850 		return -ENOMEM;
1851 	}
1852 	/* Step 2 - Must use GFP_NOIO now.
1853 	 * OK, we have enough stripes, start collecting inactive
1854 	 * stripes and copying them over
1855 	 */
1856 	hash = 0;
1857 	cnt = 0;
1858 	list_for_each_entry(nsh, &newstripes, lru) {
1859 		lock_device_hash_lock(conf, hash);
1860 		wait_event_cmd(conf->wait_for_stripe,
1861 				    !list_empty(conf->inactive_list + hash),
1862 				    unlock_device_hash_lock(conf, hash),
1863 				    lock_device_hash_lock(conf, hash));
1864 		osh = get_free_stripe(conf, hash);
1865 		unlock_device_hash_lock(conf, hash);
1866 		atomic_set(&nsh->count, 1);
1867 		for(i=0; i<conf->pool_size; i++) {
1868 			nsh->dev[i].page = osh->dev[i].page;
1869 			nsh->dev[i].orig_page = osh->dev[i].page;
1870 		}
1871 		for( ; i<newsize; i++)
1872 			nsh->dev[i].page = NULL;
1873 		nsh->hash_lock_index = hash;
1874 		kmem_cache_free(conf->slab_cache, osh);
1875 		cnt++;
1876 		if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
1877 		    !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
1878 			hash++;
1879 			cnt = 0;
1880 		}
1881 	}
1882 	kmem_cache_destroy(conf->slab_cache);
1883 
1884 	/* Step 3.
1885 	 * At this point, we are holding all the stripes so the array
1886 	 * is completely stalled, so now is a good time to resize
1887 	 * conf->disks and the scribble region
1888 	 */
1889 	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1890 	if (ndisks) {
1891 		for (i=0; i<conf->raid_disks; i++)
1892 			ndisks[i] = conf->disks[i];
1893 		kfree(conf->disks);
1894 		conf->disks = ndisks;
1895 	} else
1896 		err = -ENOMEM;
1897 
1898 	get_online_cpus();
1899 	conf->scribble_len = scribble_len(newsize);
1900 	for_each_present_cpu(cpu) {
1901 		struct raid5_percpu *percpu;
1902 		void *scribble;
1903 
1904 		percpu = per_cpu_ptr(conf->percpu, cpu);
1905 		scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1906 
1907 		if (scribble) {
1908 			kfree(percpu->scribble);
1909 			percpu->scribble = scribble;
1910 		} else {
1911 			err = -ENOMEM;
1912 			break;
1913 		}
1914 	}
1915 	put_online_cpus();
1916 
1917 	/* Step 4, return new stripes to service */
1918 	while(!list_empty(&newstripes)) {
1919 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
1920 		list_del_init(&nsh->lru);
1921 
1922 		for (i=conf->raid_disks; i < newsize; i++)
1923 			if (nsh->dev[i].page == NULL) {
1924 				struct page *p = alloc_page(GFP_NOIO);
1925 				nsh->dev[i].page = p;
1926 				nsh->dev[i].orig_page = p;
1927 				if (!p)
1928 					err = -ENOMEM;
1929 			}
1930 		release_stripe(nsh);
1931 	}
1932 	/* critical section pass, GFP_NOIO no longer needed */
1933 
1934 	conf->slab_cache = sc;
1935 	conf->active_name = 1-conf->active_name;
1936 	conf->pool_size = newsize;
1937 	return err;
1938 }
1939 
1940 static int drop_one_stripe(struct r5conf *conf, int hash)
1941 {
1942 	struct stripe_head *sh;
1943 
1944 	spin_lock_irq(conf->hash_locks + hash);
1945 	sh = get_free_stripe(conf, hash);
1946 	spin_unlock_irq(conf->hash_locks + hash);
1947 	if (!sh)
1948 		return 0;
1949 	BUG_ON(atomic_read(&sh->count));
1950 	shrink_buffers(sh);
1951 	kmem_cache_free(conf->slab_cache, sh);
1952 	atomic_dec(&conf->active_stripes);
1953 	return 1;
1954 }
1955 
1956 static void shrink_stripes(struct r5conf *conf)
1957 {
1958 	int hash;
1959 	for (hash = 0; hash < NR_STRIPE_HASH_LOCKS; hash++)
1960 		while (drop_one_stripe(conf, hash))
1961 			;
1962 
1963 	if (conf->slab_cache)
1964 		kmem_cache_destroy(conf->slab_cache);
1965 	conf->slab_cache = NULL;
1966 }
1967 
1968 static void raid5_end_read_request(struct bio * bi, int error)
1969 {
1970 	struct stripe_head *sh = bi->bi_private;
1971 	struct r5conf *conf = sh->raid_conf;
1972 	int disks = sh->disks, i;
1973 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1974 	char b[BDEVNAME_SIZE];
1975 	struct md_rdev *rdev = NULL;
1976 	sector_t s;
1977 
1978 	for (i=0 ; i<disks; i++)
1979 		if (bi == &sh->dev[i].req)
1980 			break;
1981 
1982 	pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1983 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
1984 		uptodate);
1985 	if (i == disks) {
1986 		BUG();
1987 		return;
1988 	}
1989 	if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1990 		/* If replacement finished while this request was outstanding,
1991 		 * 'replacement' might be NULL already.
1992 		 * In that case it moved down to 'rdev'.
1993 		 * rdev is not removed until all requests are finished.
1994 		 */
1995 		rdev = conf->disks[i].replacement;
1996 	if (!rdev)
1997 		rdev = conf->disks[i].rdev;
1998 
1999 	if (use_new_offset(conf, sh))
2000 		s = sh->sector + rdev->new_data_offset;
2001 	else
2002 		s = sh->sector + rdev->data_offset;
2003 	if (uptodate) {
2004 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
2005 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2006 			/* Note that this cannot happen on a
2007 			 * replacement device.  We just fail those on
2008 			 * any error
2009 			 */
2010 			printk_ratelimited(
2011 				KERN_INFO
2012 				"md/raid:%s: read error corrected"
2013 				" (%lu sectors at %llu on %s)\n",
2014 				mdname(conf->mddev), STRIPE_SECTORS,
2015 				(unsigned long long)s,
2016 				bdevname(rdev->bdev, b));
2017 			atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2018 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2019 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2020 		} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2021 			clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2022 
2023 		if (atomic_read(&rdev->read_errors))
2024 			atomic_set(&rdev->read_errors, 0);
2025 	} else {
2026 		const char *bdn = bdevname(rdev->bdev, b);
2027 		int retry = 0;
2028 		int set_bad = 0;
2029 
2030 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2031 		atomic_inc(&rdev->read_errors);
2032 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2033 			printk_ratelimited(
2034 				KERN_WARNING
2035 				"md/raid:%s: read error on replacement device "
2036 				"(sector %llu on %s).\n",
2037 				mdname(conf->mddev),
2038 				(unsigned long long)s,
2039 				bdn);
2040 		else if (conf->mddev->degraded >= conf->max_degraded) {
2041 			set_bad = 1;
2042 			printk_ratelimited(
2043 				KERN_WARNING
2044 				"md/raid:%s: read error not correctable "
2045 				"(sector %llu on %s).\n",
2046 				mdname(conf->mddev),
2047 				(unsigned long long)s,
2048 				bdn);
2049 		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2050 			/* Oh, no!!! */
2051 			set_bad = 1;
2052 			printk_ratelimited(
2053 				KERN_WARNING
2054 				"md/raid:%s: read error NOT corrected!! "
2055 				"(sector %llu on %s).\n",
2056 				mdname(conf->mddev),
2057 				(unsigned long long)s,
2058 				bdn);
2059 		} else if (atomic_read(&rdev->read_errors)
2060 			 > conf->max_nr_stripes)
2061 			printk(KERN_WARNING
2062 			       "md/raid:%s: Too many read errors, failing device %s.\n",
2063 			       mdname(conf->mddev), bdn);
2064 		else
2065 			retry = 1;
2066 		if (set_bad && test_bit(In_sync, &rdev->flags)
2067 		    && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2068 			retry = 1;
2069 		if (retry)
2070 			if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2071 				set_bit(R5_ReadError, &sh->dev[i].flags);
2072 				clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2073 			} else
2074 				set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2075 		else {
2076 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2077 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2078 			if (!(set_bad
2079 			      && test_bit(In_sync, &rdev->flags)
2080 			      && rdev_set_badblocks(
2081 				      rdev, sh->sector, STRIPE_SECTORS, 0)))
2082 				md_error(conf->mddev, rdev);
2083 		}
2084 	}
2085 	rdev_dec_pending(rdev, conf->mddev);
2086 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
2087 	set_bit(STRIPE_HANDLE, &sh->state);
2088 	release_stripe(sh);
2089 }
2090 
2091 static void raid5_end_write_request(struct bio *bi, int error)
2092 {
2093 	struct stripe_head *sh = bi->bi_private;
2094 	struct r5conf *conf = sh->raid_conf;
2095 	int disks = sh->disks, i;
2096 	struct md_rdev *uninitialized_var(rdev);
2097 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
2098 	sector_t first_bad;
2099 	int bad_sectors;
2100 	int replacement = 0;
2101 
2102 	for (i = 0 ; i < disks; i++) {
2103 		if (bi == &sh->dev[i].req) {
2104 			rdev = conf->disks[i].rdev;
2105 			break;
2106 		}
2107 		if (bi == &sh->dev[i].rreq) {
2108 			rdev = conf->disks[i].replacement;
2109 			if (rdev)
2110 				replacement = 1;
2111 			else
2112 				/* rdev was removed and 'replacement'
2113 				 * replaced it.  rdev is not removed
2114 				 * until all requests are finished.
2115 				 */
2116 				rdev = conf->disks[i].rdev;
2117 			break;
2118 		}
2119 	}
2120 	pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
2121 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2122 		uptodate);
2123 	if (i == disks) {
2124 		BUG();
2125 		return;
2126 	}
2127 
2128 	if (replacement) {
2129 		if (!uptodate)
2130 			md_error(conf->mddev, rdev);
2131 		else if (is_badblock(rdev, sh->sector,
2132 				     STRIPE_SECTORS,
2133 				     &first_bad, &bad_sectors))
2134 			set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2135 	} else {
2136 		if (!uptodate) {
2137 			set_bit(STRIPE_DEGRADED, &sh->state);
2138 			set_bit(WriteErrorSeen, &rdev->flags);
2139 			set_bit(R5_WriteError, &sh->dev[i].flags);
2140 			if (!test_and_set_bit(WantReplacement, &rdev->flags))
2141 				set_bit(MD_RECOVERY_NEEDED,
2142 					&rdev->mddev->recovery);
2143 		} else if (is_badblock(rdev, sh->sector,
2144 				       STRIPE_SECTORS,
2145 				       &first_bad, &bad_sectors)) {
2146 			set_bit(R5_MadeGood, &sh->dev[i].flags);
2147 			if (test_bit(R5_ReadError, &sh->dev[i].flags))
2148 				/* That was a successful write so make
2149 				 * sure it looks like we already did
2150 				 * a re-write.
2151 				 */
2152 				set_bit(R5_ReWrite, &sh->dev[i].flags);
2153 		}
2154 	}
2155 	rdev_dec_pending(rdev, conf->mddev);
2156 
2157 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2158 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2159 	set_bit(STRIPE_HANDLE, &sh->state);
2160 	release_stripe(sh);
2161 }
2162 
2163 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
2164 
2165 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2166 {
2167 	struct r5dev *dev = &sh->dev[i];
2168 
2169 	bio_init(&dev->req);
2170 	dev->req.bi_io_vec = &dev->vec;
2171 	dev->req.bi_max_vecs = 1;
2172 	dev->req.bi_private = sh;
2173 
2174 	bio_init(&dev->rreq);
2175 	dev->rreq.bi_io_vec = &dev->rvec;
2176 	dev->rreq.bi_max_vecs = 1;
2177 	dev->rreq.bi_private = sh;
2178 
2179 	dev->flags = 0;
2180 	dev->sector = compute_blocknr(sh, i, previous);
2181 }
2182 
2183 static void error(struct mddev *mddev, struct md_rdev *rdev)
2184 {
2185 	char b[BDEVNAME_SIZE];
2186 	struct r5conf *conf = mddev->private;
2187 	unsigned long flags;
2188 	pr_debug("raid456: error called\n");
2189 
2190 	spin_lock_irqsave(&conf->device_lock, flags);
2191 	clear_bit(In_sync, &rdev->flags);
2192 	mddev->degraded = calc_degraded(conf);
2193 	spin_unlock_irqrestore(&conf->device_lock, flags);
2194 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2195 
2196 	set_bit(Blocked, &rdev->flags);
2197 	set_bit(Faulty, &rdev->flags);
2198 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
2199 	printk(KERN_ALERT
2200 	       "md/raid:%s: Disk failure on %s, disabling device.\n"
2201 	       "md/raid:%s: Operation continuing on %d devices.\n",
2202 	       mdname(mddev),
2203 	       bdevname(rdev->bdev, b),
2204 	       mdname(mddev),
2205 	       conf->raid_disks - mddev->degraded);
2206 }
2207 
2208 /*
2209  * Input: a 'big' sector number,
2210  * Output: index of the data and parity disk, and the sector # in them.
2211  */
2212 static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2213 				     int previous, int *dd_idx,
2214 				     struct stripe_head *sh)
2215 {
2216 	sector_t stripe, stripe2;
2217 	sector_t chunk_number;
2218 	unsigned int chunk_offset;
2219 	int pd_idx, qd_idx;
2220 	int ddf_layout = 0;
2221 	sector_t new_sector;
2222 	int algorithm = previous ? conf->prev_algo
2223 				 : conf->algorithm;
2224 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2225 					 : conf->chunk_sectors;
2226 	int raid_disks = previous ? conf->previous_raid_disks
2227 				  : conf->raid_disks;
2228 	int data_disks = raid_disks - conf->max_degraded;
2229 
2230 	/* First compute the information on this sector */
2231 
2232 	/*
2233 	 * Compute the chunk number and the sector offset inside the chunk
2234 	 */
2235 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
2236 	chunk_number = r_sector;
2237 
2238 	/*
2239 	 * Compute the stripe number
2240 	 */
2241 	stripe = chunk_number;
2242 	*dd_idx = sector_div(stripe, data_disks);
2243 	stripe2 = stripe;
2244 	/*
2245 	 * Select the parity disk based on the user selected algorithm.
2246 	 */
2247 	pd_idx = qd_idx = -1;
2248 	switch(conf->level) {
2249 	case 4:
2250 		pd_idx = data_disks;
2251 		break;
2252 	case 5:
2253 		switch (algorithm) {
2254 		case ALGORITHM_LEFT_ASYMMETRIC:
2255 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2256 			if (*dd_idx >= pd_idx)
2257 				(*dd_idx)++;
2258 			break;
2259 		case ALGORITHM_RIGHT_ASYMMETRIC:
2260 			pd_idx = sector_div(stripe2, raid_disks);
2261 			if (*dd_idx >= pd_idx)
2262 				(*dd_idx)++;
2263 			break;
2264 		case ALGORITHM_LEFT_SYMMETRIC:
2265 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2266 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2267 			break;
2268 		case ALGORITHM_RIGHT_SYMMETRIC:
2269 			pd_idx = sector_div(stripe2, raid_disks);
2270 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2271 			break;
2272 		case ALGORITHM_PARITY_0:
2273 			pd_idx = 0;
2274 			(*dd_idx)++;
2275 			break;
2276 		case ALGORITHM_PARITY_N:
2277 			pd_idx = data_disks;
2278 			break;
2279 		default:
2280 			BUG();
2281 		}
2282 		break;
2283 	case 6:
2284 
2285 		switch (algorithm) {
2286 		case ALGORITHM_LEFT_ASYMMETRIC:
2287 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2288 			qd_idx = pd_idx + 1;
2289 			if (pd_idx == raid_disks-1) {
2290 				(*dd_idx)++;	/* Q D D D P */
2291 				qd_idx = 0;
2292 			} else if (*dd_idx >= pd_idx)
2293 				(*dd_idx) += 2; /* D D P Q D */
2294 			break;
2295 		case ALGORITHM_RIGHT_ASYMMETRIC:
2296 			pd_idx = sector_div(stripe2, raid_disks);
2297 			qd_idx = pd_idx + 1;
2298 			if (pd_idx == raid_disks-1) {
2299 				(*dd_idx)++;	/* Q D D D P */
2300 				qd_idx = 0;
2301 			} else if (*dd_idx >= pd_idx)
2302 				(*dd_idx) += 2; /* D D P Q D */
2303 			break;
2304 		case ALGORITHM_LEFT_SYMMETRIC:
2305 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2306 			qd_idx = (pd_idx + 1) % raid_disks;
2307 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2308 			break;
2309 		case ALGORITHM_RIGHT_SYMMETRIC:
2310 			pd_idx = sector_div(stripe2, raid_disks);
2311 			qd_idx = (pd_idx + 1) % raid_disks;
2312 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2313 			break;
2314 
2315 		case ALGORITHM_PARITY_0:
2316 			pd_idx = 0;
2317 			qd_idx = 1;
2318 			(*dd_idx) += 2;
2319 			break;
2320 		case ALGORITHM_PARITY_N:
2321 			pd_idx = data_disks;
2322 			qd_idx = data_disks + 1;
2323 			break;
2324 
2325 		case ALGORITHM_ROTATING_ZERO_RESTART:
2326 			/* Exactly the same as RIGHT_ASYMMETRIC, but or
2327 			 * of blocks for computing Q is different.
2328 			 */
2329 			pd_idx = sector_div(stripe2, raid_disks);
2330 			qd_idx = pd_idx + 1;
2331 			if (pd_idx == raid_disks-1) {
2332 				(*dd_idx)++;	/* Q D D D P */
2333 				qd_idx = 0;
2334 			} else if (*dd_idx >= pd_idx)
2335 				(*dd_idx) += 2; /* D D P Q D */
2336 			ddf_layout = 1;
2337 			break;
2338 
2339 		case ALGORITHM_ROTATING_N_RESTART:
2340 			/* Same a left_asymmetric, by first stripe is
2341 			 * D D D P Q  rather than
2342 			 * Q D D D P
2343 			 */
2344 			stripe2 += 1;
2345 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2346 			qd_idx = pd_idx + 1;
2347 			if (pd_idx == raid_disks-1) {
2348 				(*dd_idx)++;	/* Q D D D P */
2349 				qd_idx = 0;
2350 			} else if (*dd_idx >= pd_idx)
2351 				(*dd_idx) += 2; /* D D P Q D */
2352 			ddf_layout = 1;
2353 			break;
2354 
2355 		case ALGORITHM_ROTATING_N_CONTINUE:
2356 			/* Same as left_symmetric but Q is before P */
2357 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2358 			qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2359 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2360 			ddf_layout = 1;
2361 			break;
2362 
2363 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2364 			/* RAID5 left_asymmetric, with Q on last device */
2365 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2366 			if (*dd_idx >= pd_idx)
2367 				(*dd_idx)++;
2368 			qd_idx = raid_disks - 1;
2369 			break;
2370 
2371 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2372 			pd_idx = sector_div(stripe2, raid_disks-1);
2373 			if (*dd_idx >= pd_idx)
2374 				(*dd_idx)++;
2375 			qd_idx = raid_disks - 1;
2376 			break;
2377 
2378 		case ALGORITHM_LEFT_SYMMETRIC_6:
2379 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2380 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2381 			qd_idx = raid_disks - 1;
2382 			break;
2383 
2384 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2385 			pd_idx = sector_div(stripe2, raid_disks-1);
2386 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2387 			qd_idx = raid_disks - 1;
2388 			break;
2389 
2390 		case ALGORITHM_PARITY_0_6:
2391 			pd_idx = 0;
2392 			(*dd_idx)++;
2393 			qd_idx = raid_disks - 1;
2394 			break;
2395 
2396 		default:
2397 			BUG();
2398 		}
2399 		break;
2400 	}
2401 
2402 	if (sh) {
2403 		sh->pd_idx = pd_idx;
2404 		sh->qd_idx = qd_idx;
2405 		sh->ddf_layout = ddf_layout;
2406 	}
2407 	/*
2408 	 * Finally, compute the new sector number
2409 	 */
2410 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2411 	return new_sector;
2412 }
2413 
2414 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2415 {
2416 	struct r5conf *conf = sh->raid_conf;
2417 	int raid_disks = sh->disks;
2418 	int data_disks = raid_disks - conf->max_degraded;
2419 	sector_t new_sector = sh->sector, check;
2420 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2421 					 : conf->chunk_sectors;
2422 	int algorithm = previous ? conf->prev_algo
2423 				 : conf->algorithm;
2424 	sector_t stripe;
2425 	int chunk_offset;
2426 	sector_t chunk_number;
2427 	int dummy1, dd_idx = i;
2428 	sector_t r_sector;
2429 	struct stripe_head sh2;
2430 
2431 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
2432 	stripe = new_sector;
2433 
2434 	if (i == sh->pd_idx)
2435 		return 0;
2436 	switch(conf->level) {
2437 	case 4: break;
2438 	case 5:
2439 		switch (algorithm) {
2440 		case ALGORITHM_LEFT_ASYMMETRIC:
2441 		case ALGORITHM_RIGHT_ASYMMETRIC:
2442 			if (i > sh->pd_idx)
2443 				i--;
2444 			break;
2445 		case ALGORITHM_LEFT_SYMMETRIC:
2446 		case ALGORITHM_RIGHT_SYMMETRIC:
2447 			if (i < sh->pd_idx)
2448 				i += raid_disks;
2449 			i -= (sh->pd_idx + 1);
2450 			break;
2451 		case ALGORITHM_PARITY_0:
2452 			i -= 1;
2453 			break;
2454 		case ALGORITHM_PARITY_N:
2455 			break;
2456 		default:
2457 			BUG();
2458 		}
2459 		break;
2460 	case 6:
2461 		if (i == sh->qd_idx)
2462 			return 0; /* It is the Q disk */
2463 		switch (algorithm) {
2464 		case ALGORITHM_LEFT_ASYMMETRIC:
2465 		case ALGORITHM_RIGHT_ASYMMETRIC:
2466 		case ALGORITHM_ROTATING_ZERO_RESTART:
2467 		case ALGORITHM_ROTATING_N_RESTART:
2468 			if (sh->pd_idx == raid_disks-1)
2469 				i--;	/* Q D D D P */
2470 			else if (i > sh->pd_idx)
2471 				i -= 2; /* D D P Q D */
2472 			break;
2473 		case ALGORITHM_LEFT_SYMMETRIC:
2474 		case ALGORITHM_RIGHT_SYMMETRIC:
2475 			if (sh->pd_idx == raid_disks-1)
2476 				i--; /* Q D D D P */
2477 			else {
2478 				/* D D P Q D */
2479 				if (i < sh->pd_idx)
2480 					i += raid_disks;
2481 				i -= (sh->pd_idx + 2);
2482 			}
2483 			break;
2484 		case ALGORITHM_PARITY_0:
2485 			i -= 2;
2486 			break;
2487 		case ALGORITHM_PARITY_N:
2488 			break;
2489 		case ALGORITHM_ROTATING_N_CONTINUE:
2490 			/* Like left_symmetric, but P is before Q */
2491 			if (sh->pd_idx == 0)
2492 				i--;	/* P D D D Q */
2493 			else {
2494 				/* D D Q P D */
2495 				if (i < sh->pd_idx)
2496 					i += raid_disks;
2497 				i -= (sh->pd_idx + 1);
2498 			}
2499 			break;
2500 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2501 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2502 			if (i > sh->pd_idx)
2503 				i--;
2504 			break;
2505 		case ALGORITHM_LEFT_SYMMETRIC_6:
2506 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2507 			if (i < sh->pd_idx)
2508 				i += data_disks + 1;
2509 			i -= (sh->pd_idx + 1);
2510 			break;
2511 		case ALGORITHM_PARITY_0_6:
2512 			i -= 1;
2513 			break;
2514 		default:
2515 			BUG();
2516 		}
2517 		break;
2518 	}
2519 
2520 	chunk_number = stripe * data_disks + i;
2521 	r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2522 
2523 	check = raid5_compute_sector(conf, r_sector,
2524 				     previous, &dummy1, &sh2);
2525 	if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2526 		|| sh2.qd_idx != sh->qd_idx) {
2527 		printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2528 		       mdname(conf->mddev));
2529 		return 0;
2530 	}
2531 	return r_sector;
2532 }
2533 
2534 static void
2535 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2536 			 int rcw, int expand)
2537 {
2538 	int i, pd_idx = sh->pd_idx, disks = sh->disks;
2539 	struct r5conf *conf = sh->raid_conf;
2540 	int level = conf->level;
2541 
2542 	if (rcw) {
2543 
2544 		for (i = disks; i--; ) {
2545 			struct r5dev *dev = &sh->dev[i];
2546 
2547 			if (dev->towrite) {
2548 				set_bit(R5_LOCKED, &dev->flags);
2549 				set_bit(R5_Wantdrain, &dev->flags);
2550 				if (!expand)
2551 					clear_bit(R5_UPTODATE, &dev->flags);
2552 				s->locked++;
2553 			}
2554 		}
2555 		/* if we are not expanding this is a proper write request, and
2556 		 * there will be bios with new data to be drained into the
2557 		 * stripe cache
2558 		 */
2559 		if (!expand) {
2560 			if (!s->locked)
2561 				/* False alarm, nothing to do */
2562 				return;
2563 			sh->reconstruct_state = reconstruct_state_drain_run;
2564 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2565 		} else
2566 			sh->reconstruct_state = reconstruct_state_run;
2567 
2568 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2569 
2570 		if (s->locked + conf->max_degraded == disks)
2571 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2572 				atomic_inc(&conf->pending_full_writes);
2573 	} else {
2574 		BUG_ON(level == 6);
2575 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2576 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2577 
2578 		for (i = disks; i--; ) {
2579 			struct r5dev *dev = &sh->dev[i];
2580 			if (i == pd_idx)
2581 				continue;
2582 
2583 			if (dev->towrite &&
2584 			    (test_bit(R5_UPTODATE, &dev->flags) ||
2585 			     test_bit(R5_Wantcompute, &dev->flags))) {
2586 				set_bit(R5_Wantdrain, &dev->flags);
2587 				set_bit(R5_LOCKED, &dev->flags);
2588 				clear_bit(R5_UPTODATE, &dev->flags);
2589 				s->locked++;
2590 			}
2591 		}
2592 		if (!s->locked)
2593 			/* False alarm - nothing to do */
2594 			return;
2595 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2596 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2597 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2598 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2599 	}
2600 
2601 	/* keep the parity disk(s) locked while asynchronous operations
2602 	 * are in flight
2603 	 */
2604 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2605 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2606 	s->locked++;
2607 
2608 	if (level == 6) {
2609 		int qd_idx = sh->qd_idx;
2610 		struct r5dev *dev = &sh->dev[qd_idx];
2611 
2612 		set_bit(R5_LOCKED, &dev->flags);
2613 		clear_bit(R5_UPTODATE, &dev->flags);
2614 		s->locked++;
2615 	}
2616 
2617 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2618 		__func__, (unsigned long long)sh->sector,
2619 		s->locked, s->ops_request);
2620 }
2621 
2622 /*
2623  * Each stripe/dev can have one or more bion attached.
2624  * toread/towrite point to the first in a chain.
2625  * The bi_next chain must be in order.
2626  */
2627 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2628 {
2629 	struct bio **bip;
2630 	struct r5conf *conf = sh->raid_conf;
2631 	int firstwrite=0;
2632 
2633 	pr_debug("adding bi b#%llu to stripe s#%llu\n",
2634 		(unsigned long long)bi->bi_iter.bi_sector,
2635 		(unsigned long long)sh->sector);
2636 
2637 	/*
2638 	 * If several bio share a stripe. The bio bi_phys_segments acts as a
2639 	 * reference count to avoid race. The reference count should already be
2640 	 * increased before this function is called (for example, in
2641 	 * make_request()), so other bio sharing this stripe will not free the
2642 	 * stripe. If a stripe is owned by one stripe, the stripe lock will
2643 	 * protect it.
2644 	 */
2645 	spin_lock_irq(&sh->stripe_lock);
2646 	if (forwrite) {
2647 		bip = &sh->dev[dd_idx].towrite;
2648 		if (*bip == NULL)
2649 			firstwrite = 1;
2650 	} else
2651 		bip = &sh->dev[dd_idx].toread;
2652 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
2653 		if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
2654 			goto overlap;
2655 		bip = & (*bip)->bi_next;
2656 	}
2657 	if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
2658 		goto overlap;
2659 
2660 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2661 	if (*bip)
2662 		bi->bi_next = *bip;
2663 	*bip = bi;
2664 	raid5_inc_bi_active_stripes(bi);
2665 
2666 	if (forwrite) {
2667 		/* check if page is covered */
2668 		sector_t sector = sh->dev[dd_idx].sector;
2669 		for (bi=sh->dev[dd_idx].towrite;
2670 		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2671 			     bi && bi->bi_iter.bi_sector <= sector;
2672 		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2673 			if (bio_end_sector(bi) >= sector)
2674 				sector = bio_end_sector(bi);
2675 		}
2676 		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2677 			set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2678 	}
2679 
2680 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2681 		(unsigned long long)(*bip)->bi_iter.bi_sector,
2682 		(unsigned long long)sh->sector, dd_idx);
2683 	spin_unlock_irq(&sh->stripe_lock);
2684 
2685 	if (conf->mddev->bitmap && firstwrite) {
2686 		bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2687 				  STRIPE_SECTORS, 0);
2688 		sh->bm_seq = conf->seq_flush+1;
2689 		set_bit(STRIPE_BIT_DELAY, &sh->state);
2690 	}
2691 	return 1;
2692 
2693  overlap:
2694 	set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2695 	spin_unlock_irq(&sh->stripe_lock);
2696 	return 0;
2697 }
2698 
2699 static void end_reshape(struct r5conf *conf);
2700 
2701 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2702 			    struct stripe_head *sh)
2703 {
2704 	int sectors_per_chunk =
2705 		previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2706 	int dd_idx;
2707 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
2708 	int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2709 
2710 	raid5_compute_sector(conf,
2711 			     stripe * (disks - conf->max_degraded)
2712 			     *sectors_per_chunk + chunk_offset,
2713 			     previous,
2714 			     &dd_idx, sh);
2715 }
2716 
2717 static void
2718 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2719 				struct stripe_head_state *s, int disks,
2720 				struct bio **return_bi)
2721 {
2722 	int i;
2723 	for (i = disks; i--; ) {
2724 		struct bio *bi;
2725 		int bitmap_end = 0;
2726 
2727 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2728 			struct md_rdev *rdev;
2729 			rcu_read_lock();
2730 			rdev = rcu_dereference(conf->disks[i].rdev);
2731 			if (rdev && test_bit(In_sync, &rdev->flags))
2732 				atomic_inc(&rdev->nr_pending);
2733 			else
2734 				rdev = NULL;
2735 			rcu_read_unlock();
2736 			if (rdev) {
2737 				if (!rdev_set_badblocks(
2738 					    rdev,
2739 					    sh->sector,
2740 					    STRIPE_SECTORS, 0))
2741 					md_error(conf->mddev, rdev);
2742 				rdev_dec_pending(rdev, conf->mddev);
2743 			}
2744 		}
2745 		spin_lock_irq(&sh->stripe_lock);
2746 		/* fail all writes first */
2747 		bi = sh->dev[i].towrite;
2748 		sh->dev[i].towrite = NULL;
2749 		spin_unlock_irq(&sh->stripe_lock);
2750 		if (bi)
2751 			bitmap_end = 1;
2752 
2753 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2754 			wake_up(&conf->wait_for_overlap);
2755 
2756 		while (bi && bi->bi_iter.bi_sector <
2757 			sh->dev[i].sector + STRIPE_SECTORS) {
2758 			struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2759 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
2760 			if (!raid5_dec_bi_active_stripes(bi)) {
2761 				md_write_end(conf->mddev);
2762 				bi->bi_next = *return_bi;
2763 				*return_bi = bi;
2764 			}
2765 			bi = nextbi;
2766 		}
2767 		if (bitmap_end)
2768 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2769 				STRIPE_SECTORS, 0, 0);
2770 		bitmap_end = 0;
2771 		/* and fail all 'written' */
2772 		bi = sh->dev[i].written;
2773 		sh->dev[i].written = NULL;
2774 		if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
2775 			WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
2776 			sh->dev[i].page = sh->dev[i].orig_page;
2777 		}
2778 
2779 		if (bi) bitmap_end = 1;
2780 		while (bi && bi->bi_iter.bi_sector <
2781 		       sh->dev[i].sector + STRIPE_SECTORS) {
2782 			struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2783 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
2784 			if (!raid5_dec_bi_active_stripes(bi)) {
2785 				md_write_end(conf->mddev);
2786 				bi->bi_next = *return_bi;
2787 				*return_bi = bi;
2788 			}
2789 			bi = bi2;
2790 		}
2791 
2792 		/* fail any reads if this device is non-operational and
2793 		 * the data has not reached the cache yet.
2794 		 */
2795 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2796 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2797 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
2798 			spin_lock_irq(&sh->stripe_lock);
2799 			bi = sh->dev[i].toread;
2800 			sh->dev[i].toread = NULL;
2801 			spin_unlock_irq(&sh->stripe_lock);
2802 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2803 				wake_up(&conf->wait_for_overlap);
2804 			while (bi && bi->bi_iter.bi_sector <
2805 			       sh->dev[i].sector + STRIPE_SECTORS) {
2806 				struct bio *nextbi =
2807 					r5_next_bio(bi, sh->dev[i].sector);
2808 				clear_bit(BIO_UPTODATE, &bi->bi_flags);
2809 				if (!raid5_dec_bi_active_stripes(bi)) {
2810 					bi->bi_next = *return_bi;
2811 					*return_bi = bi;
2812 				}
2813 				bi = nextbi;
2814 			}
2815 		}
2816 		if (bitmap_end)
2817 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2818 					STRIPE_SECTORS, 0, 0);
2819 		/* If we were in the middle of a write the parity block might
2820 		 * still be locked - so just clear all R5_LOCKED flags
2821 		 */
2822 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2823 	}
2824 
2825 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2826 		if (atomic_dec_and_test(&conf->pending_full_writes))
2827 			md_wakeup_thread(conf->mddev->thread);
2828 }
2829 
2830 static void
2831 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2832 		   struct stripe_head_state *s)
2833 {
2834 	int abort = 0;
2835 	int i;
2836 
2837 	clear_bit(STRIPE_SYNCING, &sh->state);
2838 	if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
2839 		wake_up(&conf->wait_for_overlap);
2840 	s->syncing = 0;
2841 	s->replacing = 0;
2842 	/* There is nothing more to do for sync/check/repair.
2843 	 * Don't even need to abort as that is handled elsewhere
2844 	 * if needed, and not always wanted e.g. if there is a known
2845 	 * bad block here.
2846 	 * For recover/replace we need to record a bad block on all
2847 	 * non-sync devices, or abort the recovery
2848 	 */
2849 	if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2850 		/* During recovery devices cannot be removed, so
2851 		 * locking and refcounting of rdevs is not needed
2852 		 */
2853 		for (i = 0; i < conf->raid_disks; i++) {
2854 			struct md_rdev *rdev = conf->disks[i].rdev;
2855 			if (rdev
2856 			    && !test_bit(Faulty, &rdev->flags)
2857 			    && !test_bit(In_sync, &rdev->flags)
2858 			    && !rdev_set_badblocks(rdev, sh->sector,
2859 						   STRIPE_SECTORS, 0))
2860 				abort = 1;
2861 			rdev = conf->disks[i].replacement;
2862 			if (rdev
2863 			    && !test_bit(Faulty, &rdev->flags)
2864 			    && !test_bit(In_sync, &rdev->flags)
2865 			    && !rdev_set_badblocks(rdev, sh->sector,
2866 						   STRIPE_SECTORS, 0))
2867 				abort = 1;
2868 		}
2869 		if (abort)
2870 			conf->recovery_disabled =
2871 				conf->mddev->recovery_disabled;
2872 	}
2873 	md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2874 }
2875 
2876 static int want_replace(struct stripe_head *sh, int disk_idx)
2877 {
2878 	struct md_rdev *rdev;
2879 	int rv = 0;
2880 	/* Doing recovery so rcu locking not required */
2881 	rdev = sh->raid_conf->disks[disk_idx].replacement;
2882 	if (rdev
2883 	    && !test_bit(Faulty, &rdev->flags)
2884 	    && !test_bit(In_sync, &rdev->flags)
2885 	    && (rdev->recovery_offset <= sh->sector
2886 		|| rdev->mddev->recovery_cp <= sh->sector))
2887 		rv = 1;
2888 
2889 	return rv;
2890 }
2891 
2892 /* fetch_block - checks the given member device to see if its data needs
2893  * to be read or computed to satisfy a request.
2894  *
2895  * Returns 1 when no more member devices need to be checked, otherwise returns
2896  * 0 to tell the loop in handle_stripe_fill to continue
2897  */
2898 
2899 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
2900 			   int disk_idx, int disks)
2901 {
2902 	struct r5dev *dev = &sh->dev[disk_idx];
2903 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2904 				  &sh->dev[s->failed_num[1]] };
2905 	int i;
2906 
2907 
2908 	if (test_bit(R5_LOCKED, &dev->flags) ||
2909 	    test_bit(R5_UPTODATE, &dev->flags))
2910 		/* No point reading this as we already have it or have
2911 		 * decided to get it.
2912 		 */
2913 		return 0;
2914 
2915 	if (dev->toread ||
2916 	    (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
2917 		/* We need this block to directly satisfy a request */
2918 		return 1;
2919 
2920 	if (s->syncing || s->expanding ||
2921 	    (s->replacing && want_replace(sh, disk_idx)))
2922 		/* When syncing, or expanding we read everything.
2923 		 * When replacing, we need the replaced block.
2924 		 */
2925 		return 1;
2926 
2927 	if ((s->failed >= 1 && fdev[0]->toread) ||
2928 	    (s->failed >= 2 && fdev[1]->toread))
2929 		/* If we want to read from a failed device, then
2930 		 * we need to actually read every other device.
2931 		 */
2932 		return 1;
2933 
2934 	/* Sometimes neither read-modify-write nor reconstruct-write
2935 	 * cycles can work.  In those cases we read every block we
2936 	 * can.  Then the parity-update is certain to have enough to
2937 	 * work with.
2938 	 * This can only be a problem when we need to write something,
2939 	 * and some device has failed.  If either of those tests
2940 	 * fail we need look no further.
2941 	 */
2942 	if (!s->failed || !s->to_write)
2943 		return 0;
2944 
2945 	if (test_bit(R5_Insync, &dev->flags) &&
2946 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
2947 		/* Pre-reads at not permitted until after short delay
2948 		 * to gather multiple requests.  However if this
2949 		 * device is no Insync, the block could only be be computed
2950 		 * and there is no need to delay that.
2951 		 */
2952 		return 0;
2953 
2954 	for (i = 0; i < s->failed; i++) {
2955 		if (fdev[i]->towrite &&
2956 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
2957 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
2958 			/* If we have a partial write to a failed
2959 			 * device, then we will need to reconstruct
2960 			 * the content of that device, so all other
2961 			 * devices must be read.
2962 			 */
2963 			return 1;
2964 	}
2965 
2966 	/* If we are forced to do a reconstruct-write, either because
2967 	 * the current RAID6 implementation only supports that, or
2968 	 * or because parity cannot be trusted and we are currently
2969 	 * recovering it, there is extra need to be careful.
2970 	 * If one of the devices that we would need to read, because
2971 	 * it is not being overwritten (and maybe not written at all)
2972 	 * is missing/faulty, then we need to read everything we can.
2973 	 */
2974 	if (sh->raid_conf->level != 6 &&
2975 	    sh->sector < sh->raid_conf->mddev->recovery_cp)
2976 		/* reconstruct-write isn't being forced */
2977 		return 0;
2978 	for (i = 0; i < s->failed; i++) {
2979 		if (!test_bit(R5_UPTODATE, &fdev[i]->flags) &&
2980 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
2981 			return 1;
2982 	}
2983 
2984 	return 0;
2985 }
2986 
2987 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2988 		       int disk_idx, int disks)
2989 {
2990 	struct r5dev *dev = &sh->dev[disk_idx];
2991 
2992 	/* is the data in this block needed, and can we get it? */
2993 	if (need_this_block(sh, s, disk_idx, disks)) {
2994 		/* we would like to get this block, possibly by computing it,
2995 		 * otherwise read it if the backing disk is insync
2996 		 */
2997 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2998 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
2999 		if ((s->uptodate == disks - 1) &&
3000 		    (s->failed && (disk_idx == s->failed_num[0] ||
3001 				   disk_idx == s->failed_num[1]))) {
3002 			/* have disk failed, and we're requested to fetch it;
3003 			 * do compute it
3004 			 */
3005 			pr_debug("Computing stripe %llu block %d\n",
3006 			       (unsigned long long)sh->sector, disk_idx);
3007 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3008 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3009 			set_bit(R5_Wantcompute, &dev->flags);
3010 			sh->ops.target = disk_idx;
3011 			sh->ops.target2 = -1; /* no 2nd target */
3012 			s->req_compute = 1;
3013 			/* Careful: from this point on 'uptodate' is in the eye
3014 			 * of raid_run_ops which services 'compute' operations
3015 			 * before writes. R5_Wantcompute flags a block that will
3016 			 * be R5_UPTODATE by the time it is needed for a
3017 			 * subsequent operation.
3018 			 */
3019 			s->uptodate++;
3020 			return 1;
3021 		} else if (s->uptodate == disks-2 && s->failed >= 2) {
3022 			/* Computing 2-failure is *very* expensive; only
3023 			 * do it if failed >= 2
3024 			 */
3025 			int other;
3026 			for (other = disks; other--; ) {
3027 				if (other == disk_idx)
3028 					continue;
3029 				if (!test_bit(R5_UPTODATE,
3030 				      &sh->dev[other].flags))
3031 					break;
3032 			}
3033 			BUG_ON(other < 0);
3034 			pr_debug("Computing stripe %llu blocks %d,%d\n",
3035 			       (unsigned long long)sh->sector,
3036 			       disk_idx, other);
3037 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3038 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3039 			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3040 			set_bit(R5_Wantcompute, &sh->dev[other].flags);
3041 			sh->ops.target = disk_idx;
3042 			sh->ops.target2 = other;
3043 			s->uptodate += 2;
3044 			s->req_compute = 1;
3045 			return 1;
3046 		} else if (test_bit(R5_Insync, &dev->flags)) {
3047 			set_bit(R5_LOCKED, &dev->flags);
3048 			set_bit(R5_Wantread, &dev->flags);
3049 			s->locked++;
3050 			pr_debug("Reading block %d (sync=%d)\n",
3051 				disk_idx, s->syncing);
3052 		}
3053 	}
3054 
3055 	return 0;
3056 }
3057 
3058 /**
3059  * handle_stripe_fill - read or compute data to satisfy pending requests.
3060  */
3061 static void handle_stripe_fill(struct stripe_head *sh,
3062 			       struct stripe_head_state *s,
3063 			       int disks)
3064 {
3065 	int i;
3066 
3067 	/* look for blocks to read/compute, skip this if a compute
3068 	 * is already in flight, or if the stripe contents are in the
3069 	 * midst of changing due to a write
3070 	 */
3071 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3072 	    !sh->reconstruct_state)
3073 		for (i = disks; i--; )
3074 			if (fetch_block(sh, s, i, disks))
3075 				break;
3076 	set_bit(STRIPE_HANDLE, &sh->state);
3077 }
3078 
3079 /* handle_stripe_clean_event
3080  * any written block on an uptodate or failed drive can be returned.
3081  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3082  * never LOCKED, so we don't need to test 'failed' directly.
3083  */
3084 static void handle_stripe_clean_event(struct r5conf *conf,
3085 	struct stripe_head *sh, int disks, struct bio **return_bi)
3086 {
3087 	int i;
3088 	struct r5dev *dev;
3089 	int discard_pending = 0;
3090 
3091 	for (i = disks; i--; )
3092 		if (sh->dev[i].written) {
3093 			dev = &sh->dev[i];
3094 			if (!test_bit(R5_LOCKED, &dev->flags) &&
3095 			    (test_bit(R5_UPTODATE, &dev->flags) ||
3096 			     test_bit(R5_Discard, &dev->flags) ||
3097 			     test_bit(R5_SkipCopy, &dev->flags))) {
3098 				/* We can return any write requests */
3099 				struct bio *wbi, *wbi2;
3100 				pr_debug("Return write for disc %d\n", i);
3101 				if (test_and_clear_bit(R5_Discard, &dev->flags))
3102 					clear_bit(R5_UPTODATE, &dev->flags);
3103 				if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3104 					WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3105 					dev->page = dev->orig_page;
3106 				}
3107 				wbi = dev->written;
3108 				dev->written = NULL;
3109 				while (wbi && wbi->bi_iter.bi_sector <
3110 					dev->sector + STRIPE_SECTORS) {
3111 					wbi2 = r5_next_bio(wbi, dev->sector);
3112 					if (!raid5_dec_bi_active_stripes(wbi)) {
3113 						md_write_end(conf->mddev);
3114 						wbi->bi_next = *return_bi;
3115 						*return_bi = wbi;
3116 					}
3117 					wbi = wbi2;
3118 				}
3119 				bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3120 						STRIPE_SECTORS,
3121 					 !test_bit(STRIPE_DEGRADED, &sh->state),
3122 						0);
3123 			} else if (test_bit(R5_Discard, &dev->flags))
3124 				discard_pending = 1;
3125 			WARN_ON(test_bit(R5_SkipCopy, &dev->flags));
3126 			WARN_ON(dev->page != dev->orig_page);
3127 		}
3128 	if (!discard_pending &&
3129 	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3130 		clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3131 		clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3132 		if (sh->qd_idx >= 0) {
3133 			clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3134 			clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3135 		}
3136 		/* now that discard is done we can proceed with any sync */
3137 		clear_bit(STRIPE_DISCARD, &sh->state);
3138 		/*
3139 		 * SCSI discard will change some bio fields and the stripe has
3140 		 * no updated data, so remove it from hash list and the stripe
3141 		 * will be reinitialized
3142 		 */
3143 		spin_lock_irq(&conf->device_lock);
3144 		remove_hash(sh);
3145 		spin_unlock_irq(&conf->device_lock);
3146 		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3147 			set_bit(STRIPE_HANDLE, &sh->state);
3148 
3149 	}
3150 
3151 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3152 		if (atomic_dec_and_test(&conf->pending_full_writes))
3153 			md_wakeup_thread(conf->mddev->thread);
3154 }
3155 
3156 static void handle_stripe_dirtying(struct r5conf *conf,
3157 				   struct stripe_head *sh,
3158 				   struct stripe_head_state *s,
3159 				   int disks)
3160 {
3161 	int rmw = 0, rcw = 0, i;
3162 	sector_t recovery_cp = conf->mddev->recovery_cp;
3163 
3164 	/* RAID6 requires 'rcw' in current implementation.
3165 	 * Otherwise, check whether resync is now happening or should start.
3166 	 * If yes, then the array is dirty (after unclean shutdown or
3167 	 * initial creation), so parity in some stripes might be inconsistent.
3168 	 * In this case, we need to always do reconstruct-write, to ensure
3169 	 * that in case of drive failure or read-error correction, we
3170 	 * generate correct data from the parity.
3171 	 */
3172 	if (conf->max_degraded == 2 ||
3173 	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3174 	     s->failed == 0)) {
3175 		/* Calculate the real rcw later - for now make it
3176 		 * look like rcw is cheaper
3177 		 */
3178 		rcw = 1; rmw = 2;
3179 		pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
3180 			 conf->max_degraded, (unsigned long long)recovery_cp,
3181 			 (unsigned long long)sh->sector);
3182 	} else for (i = disks; i--; ) {
3183 		/* would I have to read this buffer for read_modify_write */
3184 		struct r5dev *dev = &sh->dev[i];
3185 		if ((dev->towrite || i == sh->pd_idx) &&
3186 		    !test_bit(R5_LOCKED, &dev->flags) &&
3187 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
3188 		      test_bit(R5_Wantcompute, &dev->flags))) {
3189 			if (test_bit(R5_Insync, &dev->flags))
3190 				rmw++;
3191 			else
3192 				rmw += 2*disks;  /* cannot read it */
3193 		}
3194 		/* Would I have to read this buffer for reconstruct_write */
3195 		if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
3196 		    !test_bit(R5_LOCKED, &dev->flags) &&
3197 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
3198 		    test_bit(R5_Wantcompute, &dev->flags))) {
3199 			if (test_bit(R5_Insync, &dev->flags))
3200 				rcw++;
3201 			else
3202 				rcw += 2*disks;
3203 		}
3204 	}
3205 	pr_debug("for sector %llu, rmw=%d rcw=%d\n",
3206 		(unsigned long long)sh->sector, rmw, rcw);
3207 	set_bit(STRIPE_HANDLE, &sh->state);
3208 	if (rmw < rcw && rmw > 0) {
3209 		/* prefer read-modify-write, but need to get some data */
3210 		if (conf->mddev->queue)
3211 			blk_add_trace_msg(conf->mddev->queue,
3212 					  "raid5 rmw %llu %d",
3213 					  (unsigned long long)sh->sector, rmw);
3214 		for (i = disks; i--; ) {
3215 			struct r5dev *dev = &sh->dev[i];
3216 			if ((dev->towrite || i == sh->pd_idx) &&
3217 			    !test_bit(R5_LOCKED, &dev->flags) &&
3218 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
3219 			    test_bit(R5_Wantcompute, &dev->flags)) &&
3220 			    test_bit(R5_Insync, &dev->flags)) {
3221 				if (test_bit(STRIPE_PREREAD_ACTIVE,
3222 					     &sh->state)) {
3223 					pr_debug("Read_old block %d for r-m-w\n",
3224 						 i);
3225 					set_bit(R5_LOCKED, &dev->flags);
3226 					set_bit(R5_Wantread, &dev->flags);
3227 					s->locked++;
3228 				} else {
3229 					set_bit(STRIPE_DELAYED, &sh->state);
3230 					set_bit(STRIPE_HANDLE, &sh->state);
3231 				}
3232 			}
3233 		}
3234 	}
3235 	if (rcw <= rmw && rcw > 0) {
3236 		/* want reconstruct write, but need to get some data */
3237 		int qread =0;
3238 		rcw = 0;
3239 		for (i = disks; i--; ) {
3240 			struct r5dev *dev = &sh->dev[i];
3241 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3242 			    i != sh->pd_idx && i != sh->qd_idx &&
3243 			    !test_bit(R5_LOCKED, &dev->flags) &&
3244 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
3245 			      test_bit(R5_Wantcompute, &dev->flags))) {
3246 				rcw++;
3247 				if (test_bit(R5_Insync, &dev->flags) &&
3248 				    test_bit(STRIPE_PREREAD_ACTIVE,
3249 					     &sh->state)) {
3250 					pr_debug("Read_old block "
3251 						"%d for Reconstruct\n", i);
3252 					set_bit(R5_LOCKED, &dev->flags);
3253 					set_bit(R5_Wantread, &dev->flags);
3254 					s->locked++;
3255 					qread++;
3256 				} else {
3257 					set_bit(STRIPE_DELAYED, &sh->state);
3258 					set_bit(STRIPE_HANDLE, &sh->state);
3259 				}
3260 			}
3261 		}
3262 		if (rcw && conf->mddev->queue)
3263 			blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3264 					  (unsigned long long)sh->sector,
3265 					  rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3266 	}
3267 
3268 	if (rcw > disks && rmw > disks &&
3269 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3270 		set_bit(STRIPE_DELAYED, &sh->state);
3271 
3272 	/* now if nothing is locked, and if we have enough data,
3273 	 * we can start a write request
3274 	 */
3275 	/* since handle_stripe can be called at any time we need to handle the
3276 	 * case where a compute block operation has been submitted and then a
3277 	 * subsequent call wants to start a write request.  raid_run_ops only
3278 	 * handles the case where compute block and reconstruct are requested
3279 	 * simultaneously.  If this is not the case then new writes need to be
3280 	 * held off until the compute completes.
3281 	 */
3282 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3283 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3284 	    !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3285 		schedule_reconstruction(sh, s, rcw == 0, 0);
3286 }
3287 
3288 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3289 				struct stripe_head_state *s, int disks)
3290 {
3291 	struct r5dev *dev = NULL;
3292 
3293 	set_bit(STRIPE_HANDLE, &sh->state);
3294 
3295 	switch (sh->check_state) {
3296 	case check_state_idle:
3297 		/* start a new check operation if there are no failures */
3298 		if (s->failed == 0) {
3299 			BUG_ON(s->uptodate != disks);
3300 			sh->check_state = check_state_run;
3301 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3302 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3303 			s->uptodate--;
3304 			break;
3305 		}
3306 		dev = &sh->dev[s->failed_num[0]];
3307 		/* fall through */
3308 	case check_state_compute_result:
3309 		sh->check_state = check_state_idle;
3310 		if (!dev)
3311 			dev = &sh->dev[sh->pd_idx];
3312 
3313 		/* check that a write has not made the stripe insync */
3314 		if (test_bit(STRIPE_INSYNC, &sh->state))
3315 			break;
3316 
3317 		/* either failed parity check, or recovery is happening */
3318 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3319 		BUG_ON(s->uptodate != disks);
3320 
3321 		set_bit(R5_LOCKED, &dev->flags);
3322 		s->locked++;
3323 		set_bit(R5_Wantwrite, &dev->flags);
3324 
3325 		clear_bit(STRIPE_DEGRADED, &sh->state);
3326 		set_bit(STRIPE_INSYNC, &sh->state);
3327 		break;
3328 	case check_state_run:
3329 		break; /* we will be called again upon completion */
3330 	case check_state_check_result:
3331 		sh->check_state = check_state_idle;
3332 
3333 		/* if a failure occurred during the check operation, leave
3334 		 * STRIPE_INSYNC not set and let the stripe be handled again
3335 		 */
3336 		if (s->failed)
3337 			break;
3338 
3339 		/* handle a successful check operation, if parity is correct
3340 		 * we are done.  Otherwise update the mismatch count and repair
3341 		 * parity if !MD_RECOVERY_CHECK
3342 		 */
3343 		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3344 			/* parity is correct (on disc,
3345 			 * not in buffer any more)
3346 			 */
3347 			set_bit(STRIPE_INSYNC, &sh->state);
3348 		else {
3349 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3350 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3351 				/* don't try to repair!! */
3352 				set_bit(STRIPE_INSYNC, &sh->state);
3353 			else {
3354 				sh->check_state = check_state_compute_run;
3355 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3356 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3357 				set_bit(R5_Wantcompute,
3358 					&sh->dev[sh->pd_idx].flags);
3359 				sh->ops.target = sh->pd_idx;
3360 				sh->ops.target2 = -1;
3361 				s->uptodate++;
3362 			}
3363 		}
3364 		break;
3365 	case check_state_compute_run:
3366 		break;
3367 	default:
3368 		printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3369 		       __func__, sh->check_state,
3370 		       (unsigned long long) sh->sector);
3371 		BUG();
3372 	}
3373 }
3374 
3375 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3376 				  struct stripe_head_state *s,
3377 				  int disks)
3378 {
3379 	int pd_idx = sh->pd_idx;
3380 	int qd_idx = sh->qd_idx;
3381 	struct r5dev *dev;
3382 
3383 	set_bit(STRIPE_HANDLE, &sh->state);
3384 
3385 	BUG_ON(s->failed > 2);
3386 
3387 	/* Want to check and possibly repair P and Q.
3388 	 * However there could be one 'failed' device, in which
3389 	 * case we can only check one of them, possibly using the
3390 	 * other to generate missing data
3391 	 */
3392 
3393 	switch (sh->check_state) {
3394 	case check_state_idle:
3395 		/* start a new check operation if there are < 2 failures */
3396 		if (s->failed == s->q_failed) {
3397 			/* The only possible failed device holds Q, so it
3398 			 * makes sense to check P (If anything else were failed,
3399 			 * we would have used P to recreate it).
3400 			 */
3401 			sh->check_state = check_state_run;
3402 		}
3403 		if (!s->q_failed && s->failed < 2) {
3404 			/* Q is not failed, and we didn't use it to generate
3405 			 * anything, so it makes sense to check it
3406 			 */
3407 			if (sh->check_state == check_state_run)
3408 				sh->check_state = check_state_run_pq;
3409 			else
3410 				sh->check_state = check_state_run_q;
3411 		}
3412 
3413 		/* discard potentially stale zero_sum_result */
3414 		sh->ops.zero_sum_result = 0;
3415 
3416 		if (sh->check_state == check_state_run) {
3417 			/* async_xor_zero_sum destroys the contents of P */
3418 			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3419 			s->uptodate--;
3420 		}
3421 		if (sh->check_state >= check_state_run &&
3422 		    sh->check_state <= check_state_run_pq) {
3423 			/* async_syndrome_zero_sum preserves P and Q, so
3424 			 * no need to mark them !uptodate here
3425 			 */
3426 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3427 			break;
3428 		}
3429 
3430 		/* we have 2-disk failure */
3431 		BUG_ON(s->failed != 2);
3432 		/* fall through */
3433 	case check_state_compute_result:
3434 		sh->check_state = check_state_idle;
3435 
3436 		/* check that a write has not made the stripe insync */
3437 		if (test_bit(STRIPE_INSYNC, &sh->state))
3438 			break;
3439 
3440 		/* now write out any block on a failed drive,
3441 		 * or P or Q if they were recomputed
3442 		 */
3443 		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3444 		if (s->failed == 2) {
3445 			dev = &sh->dev[s->failed_num[1]];
3446 			s->locked++;
3447 			set_bit(R5_LOCKED, &dev->flags);
3448 			set_bit(R5_Wantwrite, &dev->flags);
3449 		}
3450 		if (s->failed >= 1) {
3451 			dev = &sh->dev[s->failed_num[0]];
3452 			s->locked++;
3453 			set_bit(R5_LOCKED, &dev->flags);
3454 			set_bit(R5_Wantwrite, &dev->flags);
3455 		}
3456 		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3457 			dev = &sh->dev[pd_idx];
3458 			s->locked++;
3459 			set_bit(R5_LOCKED, &dev->flags);
3460 			set_bit(R5_Wantwrite, &dev->flags);
3461 		}
3462 		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3463 			dev = &sh->dev[qd_idx];
3464 			s->locked++;
3465 			set_bit(R5_LOCKED, &dev->flags);
3466 			set_bit(R5_Wantwrite, &dev->flags);
3467 		}
3468 		clear_bit(STRIPE_DEGRADED, &sh->state);
3469 
3470 		set_bit(STRIPE_INSYNC, &sh->state);
3471 		break;
3472 	case check_state_run:
3473 	case check_state_run_q:
3474 	case check_state_run_pq:
3475 		break; /* we will be called again upon completion */
3476 	case check_state_check_result:
3477 		sh->check_state = check_state_idle;
3478 
3479 		/* handle a successful check operation, if parity is correct
3480 		 * we are done.  Otherwise update the mismatch count and repair
3481 		 * parity if !MD_RECOVERY_CHECK
3482 		 */
3483 		if (sh->ops.zero_sum_result == 0) {
3484 			/* both parities are correct */
3485 			if (!s->failed)
3486 				set_bit(STRIPE_INSYNC, &sh->state);
3487 			else {
3488 				/* in contrast to the raid5 case we can validate
3489 				 * parity, but still have a failure to write
3490 				 * back
3491 				 */
3492 				sh->check_state = check_state_compute_result;
3493 				/* Returning at this point means that we may go
3494 				 * off and bring p and/or q uptodate again so
3495 				 * we make sure to check zero_sum_result again
3496 				 * to verify if p or q need writeback
3497 				 */
3498 			}
3499 		} else {
3500 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3501 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3502 				/* don't try to repair!! */
3503 				set_bit(STRIPE_INSYNC, &sh->state);
3504 			else {
3505 				int *target = &sh->ops.target;
3506 
3507 				sh->ops.target = -1;
3508 				sh->ops.target2 = -1;
3509 				sh->check_state = check_state_compute_run;
3510 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3511 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3512 				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3513 					set_bit(R5_Wantcompute,
3514 						&sh->dev[pd_idx].flags);
3515 					*target = pd_idx;
3516 					target = &sh->ops.target2;
3517 					s->uptodate++;
3518 				}
3519 				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3520 					set_bit(R5_Wantcompute,
3521 						&sh->dev[qd_idx].flags);
3522 					*target = qd_idx;
3523 					s->uptodate++;
3524 				}
3525 			}
3526 		}
3527 		break;
3528 	case check_state_compute_run:
3529 		break;
3530 	default:
3531 		printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3532 		       __func__, sh->check_state,
3533 		       (unsigned long long) sh->sector);
3534 		BUG();
3535 	}
3536 }
3537 
3538 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3539 {
3540 	int i;
3541 
3542 	/* We have read all the blocks in this stripe and now we need to
3543 	 * copy some of them into a target stripe for expand.
3544 	 */
3545 	struct dma_async_tx_descriptor *tx = NULL;
3546 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3547 	for (i = 0; i < sh->disks; i++)
3548 		if (i != sh->pd_idx && i != sh->qd_idx) {
3549 			int dd_idx, j;
3550 			struct stripe_head *sh2;
3551 			struct async_submit_ctl submit;
3552 
3553 			sector_t bn = compute_blocknr(sh, i, 1);
3554 			sector_t s = raid5_compute_sector(conf, bn, 0,
3555 							  &dd_idx, NULL);
3556 			sh2 = get_active_stripe(conf, s, 0, 1, 1);
3557 			if (sh2 == NULL)
3558 				/* so far only the early blocks of this stripe
3559 				 * have been requested.  When later blocks
3560 				 * get requested, we will try again
3561 				 */
3562 				continue;
3563 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3564 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3565 				/* must have already done this block */
3566 				release_stripe(sh2);
3567 				continue;
3568 			}
3569 
3570 			/* place all the copies on one channel */
3571 			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3572 			tx = async_memcpy(sh2->dev[dd_idx].page,
3573 					  sh->dev[i].page, 0, 0, STRIPE_SIZE,
3574 					  &submit);
3575 
3576 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3577 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3578 			for (j = 0; j < conf->raid_disks; j++)
3579 				if (j != sh2->pd_idx &&
3580 				    j != sh2->qd_idx &&
3581 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
3582 					break;
3583 			if (j == conf->raid_disks) {
3584 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
3585 				set_bit(STRIPE_HANDLE, &sh2->state);
3586 			}
3587 			release_stripe(sh2);
3588 
3589 		}
3590 	/* done submitting copies, wait for them to complete */
3591 	async_tx_quiesce(&tx);
3592 }
3593 
3594 /*
3595  * handle_stripe - do things to a stripe.
3596  *
3597  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3598  * state of various bits to see what needs to be done.
3599  * Possible results:
3600  *    return some read requests which now have data
3601  *    return some write requests which are safely on storage
3602  *    schedule a read on some buffers
3603  *    schedule a write of some buffers
3604  *    return confirmation of parity correctness
3605  *
3606  */
3607 
3608 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3609 {
3610 	struct r5conf *conf = sh->raid_conf;
3611 	int disks = sh->disks;
3612 	struct r5dev *dev;
3613 	int i;
3614 	int do_recovery = 0;
3615 
3616 	memset(s, 0, sizeof(*s));
3617 
3618 	s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3619 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3620 	s->failed_num[0] = -1;
3621 	s->failed_num[1] = -1;
3622 
3623 	/* Now to look around and see what can be done */
3624 	rcu_read_lock();
3625 	for (i=disks; i--; ) {
3626 		struct md_rdev *rdev;
3627 		sector_t first_bad;
3628 		int bad_sectors;
3629 		int is_bad = 0;
3630 
3631 		dev = &sh->dev[i];
3632 
3633 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3634 			 i, dev->flags,
3635 			 dev->toread, dev->towrite, dev->written);
3636 		/* maybe we can reply to a read
3637 		 *
3638 		 * new wantfill requests are only permitted while
3639 		 * ops_complete_biofill is guaranteed to be inactive
3640 		 */
3641 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3642 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3643 			set_bit(R5_Wantfill, &dev->flags);
3644 
3645 		/* now count some things */
3646 		if (test_bit(R5_LOCKED, &dev->flags))
3647 			s->locked++;
3648 		if (test_bit(R5_UPTODATE, &dev->flags))
3649 			s->uptodate++;
3650 		if (test_bit(R5_Wantcompute, &dev->flags)) {
3651 			s->compute++;
3652 			BUG_ON(s->compute > 2);
3653 		}
3654 
3655 		if (test_bit(R5_Wantfill, &dev->flags))
3656 			s->to_fill++;
3657 		else if (dev->toread)
3658 			s->to_read++;
3659 		if (dev->towrite) {
3660 			s->to_write++;
3661 			if (!test_bit(R5_OVERWRITE, &dev->flags))
3662 				s->non_overwrite++;
3663 		}
3664 		if (dev->written)
3665 			s->written++;
3666 		/* Prefer to use the replacement for reads, but only
3667 		 * if it is recovered enough and has no bad blocks.
3668 		 */
3669 		rdev = rcu_dereference(conf->disks[i].replacement);
3670 		if (rdev && !test_bit(Faulty, &rdev->flags) &&
3671 		    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3672 		    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3673 				 &first_bad, &bad_sectors))
3674 			set_bit(R5_ReadRepl, &dev->flags);
3675 		else {
3676 			if (rdev)
3677 				set_bit(R5_NeedReplace, &dev->flags);
3678 			rdev = rcu_dereference(conf->disks[i].rdev);
3679 			clear_bit(R5_ReadRepl, &dev->flags);
3680 		}
3681 		if (rdev && test_bit(Faulty, &rdev->flags))
3682 			rdev = NULL;
3683 		if (rdev) {
3684 			is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3685 					     &first_bad, &bad_sectors);
3686 			if (s->blocked_rdev == NULL
3687 			    && (test_bit(Blocked, &rdev->flags)
3688 				|| is_bad < 0)) {
3689 				if (is_bad < 0)
3690 					set_bit(BlockedBadBlocks,
3691 						&rdev->flags);
3692 				s->blocked_rdev = rdev;
3693 				atomic_inc(&rdev->nr_pending);
3694 			}
3695 		}
3696 		clear_bit(R5_Insync, &dev->flags);
3697 		if (!rdev)
3698 			/* Not in-sync */;
3699 		else if (is_bad) {
3700 			/* also not in-sync */
3701 			if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3702 			    test_bit(R5_UPTODATE, &dev->flags)) {
3703 				/* treat as in-sync, but with a read error
3704 				 * which we can now try to correct
3705 				 */
3706 				set_bit(R5_Insync, &dev->flags);
3707 				set_bit(R5_ReadError, &dev->flags);
3708 			}
3709 		} else if (test_bit(In_sync, &rdev->flags))
3710 			set_bit(R5_Insync, &dev->flags);
3711 		else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3712 			/* in sync if before recovery_offset */
3713 			set_bit(R5_Insync, &dev->flags);
3714 		else if (test_bit(R5_UPTODATE, &dev->flags) &&
3715 			 test_bit(R5_Expanded, &dev->flags))
3716 			/* If we've reshaped into here, we assume it is Insync.
3717 			 * We will shortly update recovery_offset to make
3718 			 * it official.
3719 			 */
3720 			set_bit(R5_Insync, &dev->flags);
3721 
3722 		if (test_bit(R5_WriteError, &dev->flags)) {
3723 			/* This flag does not apply to '.replacement'
3724 			 * only to .rdev, so make sure to check that*/
3725 			struct md_rdev *rdev2 = rcu_dereference(
3726 				conf->disks[i].rdev);
3727 			if (rdev2 == rdev)
3728 				clear_bit(R5_Insync, &dev->flags);
3729 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3730 				s->handle_bad_blocks = 1;
3731 				atomic_inc(&rdev2->nr_pending);
3732 			} else
3733 				clear_bit(R5_WriteError, &dev->flags);
3734 		}
3735 		if (test_bit(R5_MadeGood, &dev->flags)) {
3736 			/* This flag does not apply to '.replacement'
3737 			 * only to .rdev, so make sure to check that*/
3738 			struct md_rdev *rdev2 = rcu_dereference(
3739 				conf->disks[i].rdev);
3740 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3741 				s->handle_bad_blocks = 1;
3742 				atomic_inc(&rdev2->nr_pending);
3743 			} else
3744 				clear_bit(R5_MadeGood, &dev->flags);
3745 		}
3746 		if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3747 			struct md_rdev *rdev2 = rcu_dereference(
3748 				conf->disks[i].replacement);
3749 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3750 				s->handle_bad_blocks = 1;
3751 				atomic_inc(&rdev2->nr_pending);
3752 			} else
3753 				clear_bit(R5_MadeGoodRepl, &dev->flags);
3754 		}
3755 		if (!test_bit(R5_Insync, &dev->flags)) {
3756 			/* The ReadError flag will just be confusing now */
3757 			clear_bit(R5_ReadError, &dev->flags);
3758 			clear_bit(R5_ReWrite, &dev->flags);
3759 		}
3760 		if (test_bit(R5_ReadError, &dev->flags))
3761 			clear_bit(R5_Insync, &dev->flags);
3762 		if (!test_bit(R5_Insync, &dev->flags)) {
3763 			if (s->failed < 2)
3764 				s->failed_num[s->failed] = i;
3765 			s->failed++;
3766 			if (rdev && !test_bit(Faulty, &rdev->flags))
3767 				do_recovery = 1;
3768 		}
3769 	}
3770 	if (test_bit(STRIPE_SYNCING, &sh->state)) {
3771 		/* If there is a failed device being replaced,
3772 		 *     we must be recovering.
3773 		 * else if we are after recovery_cp, we must be syncing
3774 		 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3775 		 * else we can only be replacing
3776 		 * sync and recovery both need to read all devices, and so
3777 		 * use the same flag.
3778 		 */
3779 		if (do_recovery ||
3780 		    sh->sector >= conf->mddev->recovery_cp ||
3781 		    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3782 			s->syncing = 1;
3783 		else
3784 			s->replacing = 1;
3785 	}
3786 	rcu_read_unlock();
3787 }
3788 
3789 static void handle_stripe(struct stripe_head *sh)
3790 {
3791 	struct stripe_head_state s;
3792 	struct r5conf *conf = sh->raid_conf;
3793 	int i;
3794 	int prexor;
3795 	int disks = sh->disks;
3796 	struct r5dev *pdev, *qdev;
3797 
3798 	clear_bit(STRIPE_HANDLE, &sh->state);
3799 	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3800 		/* already being handled, ensure it gets handled
3801 		 * again when current action finishes */
3802 		set_bit(STRIPE_HANDLE, &sh->state);
3803 		return;
3804 	}
3805 
3806 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3807 		spin_lock(&sh->stripe_lock);
3808 		/* Cannot process 'sync' concurrently with 'discard' */
3809 		if (!test_bit(STRIPE_DISCARD, &sh->state) &&
3810 		    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3811 			set_bit(STRIPE_SYNCING, &sh->state);
3812 			clear_bit(STRIPE_INSYNC, &sh->state);
3813 			clear_bit(STRIPE_REPLACED, &sh->state);
3814 		}
3815 		spin_unlock(&sh->stripe_lock);
3816 	}
3817 	clear_bit(STRIPE_DELAYED, &sh->state);
3818 
3819 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3820 		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3821 	       (unsigned long long)sh->sector, sh->state,
3822 	       atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3823 	       sh->check_state, sh->reconstruct_state);
3824 
3825 	analyse_stripe(sh, &s);
3826 
3827 	if (s.handle_bad_blocks) {
3828 		set_bit(STRIPE_HANDLE, &sh->state);
3829 		goto finish;
3830 	}
3831 
3832 	if (unlikely(s.blocked_rdev)) {
3833 		if (s.syncing || s.expanding || s.expanded ||
3834 		    s.replacing || s.to_write || s.written) {
3835 			set_bit(STRIPE_HANDLE, &sh->state);
3836 			goto finish;
3837 		}
3838 		/* There is nothing for the blocked_rdev to block */
3839 		rdev_dec_pending(s.blocked_rdev, conf->mddev);
3840 		s.blocked_rdev = NULL;
3841 	}
3842 
3843 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3844 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3845 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3846 	}
3847 
3848 	pr_debug("locked=%d uptodate=%d to_read=%d"
3849 	       " to_write=%d failed=%d failed_num=%d,%d\n",
3850 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3851 	       s.failed_num[0], s.failed_num[1]);
3852 	/* check if the array has lost more than max_degraded devices and,
3853 	 * if so, some requests might need to be failed.
3854 	 */
3855 	if (s.failed > conf->max_degraded) {
3856 		sh->check_state = 0;
3857 		sh->reconstruct_state = 0;
3858 		if (s.to_read+s.to_write+s.written)
3859 			handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3860 		if (s.syncing + s.replacing)
3861 			handle_failed_sync(conf, sh, &s);
3862 	}
3863 
3864 	/* Now we check to see if any write operations have recently
3865 	 * completed
3866 	 */
3867 	prexor = 0;
3868 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3869 		prexor = 1;
3870 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
3871 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3872 		sh->reconstruct_state = reconstruct_state_idle;
3873 
3874 		/* All the 'written' buffers and the parity block are ready to
3875 		 * be written back to disk
3876 		 */
3877 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3878 		       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3879 		BUG_ON(sh->qd_idx >= 0 &&
3880 		       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3881 		       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3882 		for (i = disks; i--; ) {
3883 			struct r5dev *dev = &sh->dev[i];
3884 			if (test_bit(R5_LOCKED, &dev->flags) &&
3885 				(i == sh->pd_idx || i == sh->qd_idx ||
3886 				 dev->written)) {
3887 				pr_debug("Writing block %d\n", i);
3888 				set_bit(R5_Wantwrite, &dev->flags);
3889 				if (prexor)
3890 					continue;
3891 				if (s.failed > 1)
3892 					continue;
3893 				if (!test_bit(R5_Insync, &dev->flags) ||
3894 				    ((i == sh->pd_idx || i == sh->qd_idx)  &&
3895 				     s.failed == 0))
3896 					set_bit(STRIPE_INSYNC, &sh->state);
3897 			}
3898 		}
3899 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3900 			s.dec_preread_active = 1;
3901 	}
3902 
3903 	/*
3904 	 * might be able to return some write requests if the parity blocks
3905 	 * are safe, or on a failed drive
3906 	 */
3907 	pdev = &sh->dev[sh->pd_idx];
3908 	s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3909 		|| (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3910 	qdev = &sh->dev[sh->qd_idx];
3911 	s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3912 		|| (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3913 		|| conf->level < 6;
3914 
3915 	if (s.written &&
3916 	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3917 			     && !test_bit(R5_LOCKED, &pdev->flags)
3918 			     && (test_bit(R5_UPTODATE, &pdev->flags) ||
3919 				 test_bit(R5_Discard, &pdev->flags))))) &&
3920 	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3921 			     && !test_bit(R5_LOCKED, &qdev->flags)
3922 			     && (test_bit(R5_UPTODATE, &qdev->flags) ||
3923 				 test_bit(R5_Discard, &qdev->flags))))))
3924 		handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3925 
3926 	/* Now we might consider reading some blocks, either to check/generate
3927 	 * parity, or to satisfy requests
3928 	 * or to load a block that is being partially written.
3929 	 */
3930 	if (s.to_read || s.non_overwrite
3931 	    || (conf->level == 6 && s.to_write && s.failed)
3932 	    || (s.syncing && (s.uptodate + s.compute < disks))
3933 	    || s.replacing
3934 	    || s.expanding)
3935 		handle_stripe_fill(sh, &s, disks);
3936 
3937 	/* Now to consider new write requests and what else, if anything
3938 	 * should be read.  We do not handle new writes when:
3939 	 * 1/ A 'write' operation (copy+xor) is already in flight.
3940 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
3941 	 *    block.
3942 	 */
3943 	if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3944 		handle_stripe_dirtying(conf, sh, &s, disks);
3945 
3946 	/* maybe we need to check and possibly fix the parity for this stripe
3947 	 * Any reads will already have been scheduled, so we just see if enough
3948 	 * data is available.  The parity check is held off while parity
3949 	 * dependent operations are in flight.
3950 	 */
3951 	if (sh->check_state ||
3952 	    (s.syncing && s.locked == 0 &&
3953 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3954 	     !test_bit(STRIPE_INSYNC, &sh->state))) {
3955 		if (conf->level == 6)
3956 			handle_parity_checks6(conf, sh, &s, disks);
3957 		else
3958 			handle_parity_checks5(conf, sh, &s, disks);
3959 	}
3960 
3961 	if ((s.replacing || s.syncing) && s.locked == 0
3962 	    && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
3963 	    && !test_bit(STRIPE_REPLACED, &sh->state)) {
3964 		/* Write out to replacement devices where possible */
3965 		for (i = 0; i < conf->raid_disks; i++)
3966 			if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3967 				WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
3968 				set_bit(R5_WantReplace, &sh->dev[i].flags);
3969 				set_bit(R5_LOCKED, &sh->dev[i].flags);
3970 				s.locked++;
3971 			}
3972 		if (s.replacing)
3973 			set_bit(STRIPE_INSYNC, &sh->state);
3974 		set_bit(STRIPE_REPLACED, &sh->state);
3975 	}
3976 	if ((s.syncing || s.replacing) && s.locked == 0 &&
3977 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3978 	    test_bit(STRIPE_INSYNC, &sh->state)) {
3979 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3980 		clear_bit(STRIPE_SYNCING, &sh->state);
3981 		if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3982 			wake_up(&conf->wait_for_overlap);
3983 	}
3984 
3985 	/* If the failed drives are just a ReadError, then we might need
3986 	 * to progress the repair/check process
3987 	 */
3988 	if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3989 		for (i = 0; i < s.failed; i++) {
3990 			struct r5dev *dev = &sh->dev[s.failed_num[i]];
3991 			if (test_bit(R5_ReadError, &dev->flags)
3992 			    && !test_bit(R5_LOCKED, &dev->flags)
3993 			    && test_bit(R5_UPTODATE, &dev->flags)
3994 				) {
3995 				if (!test_bit(R5_ReWrite, &dev->flags)) {
3996 					set_bit(R5_Wantwrite, &dev->flags);
3997 					set_bit(R5_ReWrite, &dev->flags);
3998 					set_bit(R5_LOCKED, &dev->flags);
3999 					s.locked++;
4000 				} else {
4001 					/* let's read it back */
4002 					set_bit(R5_Wantread, &dev->flags);
4003 					set_bit(R5_LOCKED, &dev->flags);
4004 					s.locked++;
4005 				}
4006 			}
4007 		}
4008 
4009 	/* Finish reconstruct operations initiated by the expansion process */
4010 	if (sh->reconstruct_state == reconstruct_state_result) {
4011 		struct stripe_head *sh_src
4012 			= get_active_stripe(conf, sh->sector, 1, 1, 1);
4013 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4014 			/* sh cannot be written until sh_src has been read.
4015 			 * so arrange for sh to be delayed a little
4016 			 */
4017 			set_bit(STRIPE_DELAYED, &sh->state);
4018 			set_bit(STRIPE_HANDLE, &sh->state);
4019 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4020 					      &sh_src->state))
4021 				atomic_inc(&conf->preread_active_stripes);
4022 			release_stripe(sh_src);
4023 			goto finish;
4024 		}
4025 		if (sh_src)
4026 			release_stripe(sh_src);
4027 
4028 		sh->reconstruct_state = reconstruct_state_idle;
4029 		clear_bit(STRIPE_EXPANDING, &sh->state);
4030 		for (i = conf->raid_disks; i--; ) {
4031 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
4032 			set_bit(R5_LOCKED, &sh->dev[i].flags);
4033 			s.locked++;
4034 		}
4035 	}
4036 
4037 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4038 	    !sh->reconstruct_state) {
4039 		/* Need to write out all blocks after computing parity */
4040 		sh->disks = conf->raid_disks;
4041 		stripe_set_idx(sh->sector, conf, 0, sh);
4042 		schedule_reconstruction(sh, &s, 1, 1);
4043 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4044 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
4045 		atomic_dec(&conf->reshape_stripes);
4046 		wake_up(&conf->wait_for_overlap);
4047 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4048 	}
4049 
4050 	if (s.expanding && s.locked == 0 &&
4051 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4052 		handle_stripe_expansion(conf, sh);
4053 
4054 finish:
4055 	/* wait for this device to become unblocked */
4056 	if (unlikely(s.blocked_rdev)) {
4057 		if (conf->mddev->external)
4058 			md_wait_for_blocked_rdev(s.blocked_rdev,
4059 						 conf->mddev);
4060 		else
4061 			/* Internal metadata will immediately
4062 			 * be written by raid5d, so we don't
4063 			 * need to wait here.
4064 			 */
4065 			rdev_dec_pending(s.blocked_rdev,
4066 					 conf->mddev);
4067 	}
4068 
4069 	if (s.handle_bad_blocks)
4070 		for (i = disks; i--; ) {
4071 			struct md_rdev *rdev;
4072 			struct r5dev *dev = &sh->dev[i];
4073 			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4074 				/* We own a safe reference to the rdev */
4075 				rdev = conf->disks[i].rdev;
4076 				if (!rdev_set_badblocks(rdev, sh->sector,
4077 							STRIPE_SECTORS, 0))
4078 					md_error(conf->mddev, rdev);
4079 				rdev_dec_pending(rdev, conf->mddev);
4080 			}
4081 			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4082 				rdev = conf->disks[i].rdev;
4083 				rdev_clear_badblocks(rdev, sh->sector,
4084 						     STRIPE_SECTORS, 0);
4085 				rdev_dec_pending(rdev, conf->mddev);
4086 			}
4087 			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4088 				rdev = conf->disks[i].replacement;
4089 				if (!rdev)
4090 					/* rdev have been moved down */
4091 					rdev = conf->disks[i].rdev;
4092 				rdev_clear_badblocks(rdev, sh->sector,
4093 						     STRIPE_SECTORS, 0);
4094 				rdev_dec_pending(rdev, conf->mddev);
4095 			}
4096 		}
4097 
4098 	if (s.ops_request)
4099 		raid_run_ops(sh, s.ops_request);
4100 
4101 	ops_run_io(sh, &s);
4102 
4103 	if (s.dec_preread_active) {
4104 		/* We delay this until after ops_run_io so that if make_request
4105 		 * is waiting on a flush, it won't continue until the writes
4106 		 * have actually been submitted.
4107 		 */
4108 		atomic_dec(&conf->preread_active_stripes);
4109 		if (atomic_read(&conf->preread_active_stripes) <
4110 		    IO_THRESHOLD)
4111 			md_wakeup_thread(conf->mddev->thread);
4112 	}
4113 
4114 	return_io(s.return_bi);
4115 
4116 	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4117 }
4118 
4119 static void raid5_activate_delayed(struct r5conf *conf)
4120 {
4121 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4122 		while (!list_empty(&conf->delayed_list)) {
4123 			struct list_head *l = conf->delayed_list.next;
4124 			struct stripe_head *sh;
4125 			sh = list_entry(l, struct stripe_head, lru);
4126 			list_del_init(l);
4127 			clear_bit(STRIPE_DELAYED, &sh->state);
4128 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4129 				atomic_inc(&conf->preread_active_stripes);
4130 			list_add_tail(&sh->lru, &conf->hold_list);
4131 			raid5_wakeup_stripe_thread(sh);
4132 		}
4133 	}
4134 }
4135 
4136 static void activate_bit_delay(struct r5conf *conf,
4137 	struct list_head *temp_inactive_list)
4138 {
4139 	/* device_lock is held */
4140 	struct list_head head;
4141 	list_add(&head, &conf->bitmap_list);
4142 	list_del_init(&conf->bitmap_list);
4143 	while (!list_empty(&head)) {
4144 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4145 		int hash;
4146 		list_del_init(&sh->lru);
4147 		atomic_inc(&sh->count);
4148 		hash = sh->hash_lock_index;
4149 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
4150 	}
4151 }
4152 
4153 static int raid5_congested(struct mddev *mddev, int bits)
4154 {
4155 	struct r5conf *conf = mddev->private;
4156 
4157 	/* No difference between reads and writes.  Just check
4158 	 * how busy the stripe_cache is
4159 	 */
4160 
4161 	if (conf->inactive_blocked)
4162 		return 1;
4163 	if (conf->quiesce)
4164 		return 1;
4165 	if (atomic_read(&conf->empty_inactive_list_nr))
4166 		return 1;
4167 
4168 	return 0;
4169 }
4170 
4171 /* We want read requests to align with chunks where possible,
4172  * but write requests don't need to.
4173  */
4174 static int raid5_mergeable_bvec(struct mddev *mddev,
4175 				struct bvec_merge_data *bvm,
4176 				struct bio_vec *biovec)
4177 {
4178 	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
4179 	int max;
4180 	unsigned int chunk_sectors = mddev->chunk_sectors;
4181 	unsigned int bio_sectors = bvm->bi_size >> 9;
4182 
4183 	if ((bvm->bi_rw & 1) == WRITE)
4184 		return biovec->bv_len; /* always allow writes to be mergeable */
4185 
4186 	if (mddev->new_chunk_sectors < mddev->chunk_sectors)
4187 		chunk_sectors = mddev->new_chunk_sectors;
4188 	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
4189 	if (max < 0) max = 0;
4190 	if (max <= biovec->bv_len && bio_sectors == 0)
4191 		return biovec->bv_len;
4192 	else
4193 		return max;
4194 }
4195 
4196 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4197 {
4198 	sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4199 	unsigned int chunk_sectors = mddev->chunk_sectors;
4200 	unsigned int bio_sectors = bio_sectors(bio);
4201 
4202 	if (mddev->new_chunk_sectors < mddev->chunk_sectors)
4203 		chunk_sectors = mddev->new_chunk_sectors;
4204 	return  chunk_sectors >=
4205 		((sector & (chunk_sectors - 1)) + bio_sectors);
4206 }
4207 
4208 /*
4209  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4210  *  later sampled by raid5d.
4211  */
4212 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4213 {
4214 	unsigned long flags;
4215 
4216 	spin_lock_irqsave(&conf->device_lock, flags);
4217 
4218 	bi->bi_next = conf->retry_read_aligned_list;
4219 	conf->retry_read_aligned_list = bi;
4220 
4221 	spin_unlock_irqrestore(&conf->device_lock, flags);
4222 	md_wakeup_thread(conf->mddev->thread);
4223 }
4224 
4225 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4226 {
4227 	struct bio *bi;
4228 
4229 	bi = conf->retry_read_aligned;
4230 	if (bi) {
4231 		conf->retry_read_aligned = NULL;
4232 		return bi;
4233 	}
4234 	bi = conf->retry_read_aligned_list;
4235 	if(bi) {
4236 		conf->retry_read_aligned_list = bi->bi_next;
4237 		bi->bi_next = NULL;
4238 		/*
4239 		 * this sets the active strip count to 1 and the processed
4240 		 * strip count to zero (upper 8 bits)
4241 		 */
4242 		raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
4243 	}
4244 
4245 	return bi;
4246 }
4247 
4248 /*
4249  *  The "raid5_align_endio" should check if the read succeeded and if it
4250  *  did, call bio_endio on the original bio (having bio_put the new bio
4251  *  first).
4252  *  If the read failed..
4253  */
4254 static void raid5_align_endio(struct bio *bi, int error)
4255 {
4256 	struct bio* raid_bi  = bi->bi_private;
4257 	struct mddev *mddev;
4258 	struct r5conf *conf;
4259 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
4260 	struct md_rdev *rdev;
4261 
4262 	bio_put(bi);
4263 
4264 	rdev = (void*)raid_bi->bi_next;
4265 	raid_bi->bi_next = NULL;
4266 	mddev = rdev->mddev;
4267 	conf = mddev->private;
4268 
4269 	rdev_dec_pending(rdev, conf->mddev);
4270 
4271 	if (!error && uptodate) {
4272 		trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
4273 					 raid_bi, 0);
4274 		bio_endio(raid_bi, 0);
4275 		if (atomic_dec_and_test(&conf->active_aligned_reads))
4276 			wake_up(&conf->wait_for_stripe);
4277 		return;
4278 	}
4279 
4280 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
4281 
4282 	add_bio_to_retry(raid_bi, conf);
4283 }
4284 
4285 static int bio_fits_rdev(struct bio *bi)
4286 {
4287 	struct request_queue *q = bdev_get_queue(bi->bi_bdev);
4288 
4289 	if (bio_sectors(bi) > queue_max_sectors(q))
4290 		return 0;
4291 	blk_recount_segments(q, bi);
4292 	if (bi->bi_phys_segments > queue_max_segments(q))
4293 		return 0;
4294 
4295 	if (q->merge_bvec_fn)
4296 		/* it's too hard to apply the merge_bvec_fn at this stage,
4297 		 * just just give up
4298 		 */
4299 		return 0;
4300 
4301 	return 1;
4302 }
4303 
4304 static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
4305 {
4306 	struct r5conf *conf = mddev->private;
4307 	int dd_idx;
4308 	struct bio* align_bi;
4309 	struct md_rdev *rdev;
4310 	sector_t end_sector;
4311 
4312 	if (!in_chunk_boundary(mddev, raid_bio)) {
4313 		pr_debug("chunk_aligned_read : non aligned\n");
4314 		return 0;
4315 	}
4316 	/*
4317 	 * use bio_clone_mddev to make a copy of the bio
4318 	 */
4319 	align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4320 	if (!align_bi)
4321 		return 0;
4322 	/*
4323 	 *   set bi_end_io to a new function, and set bi_private to the
4324 	 *     original bio.
4325 	 */
4326 	align_bi->bi_end_io  = raid5_align_endio;
4327 	align_bi->bi_private = raid_bio;
4328 	/*
4329 	 *	compute position
4330 	 */
4331 	align_bi->bi_iter.bi_sector =
4332 		raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
4333 				     0, &dd_idx, NULL);
4334 
4335 	end_sector = bio_end_sector(align_bi);
4336 	rcu_read_lock();
4337 	rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4338 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
4339 	    rdev->recovery_offset < end_sector) {
4340 		rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4341 		if (rdev &&
4342 		    (test_bit(Faulty, &rdev->flags) ||
4343 		    !(test_bit(In_sync, &rdev->flags) ||
4344 		      rdev->recovery_offset >= end_sector)))
4345 			rdev = NULL;
4346 	}
4347 	if (rdev) {
4348 		sector_t first_bad;
4349 		int bad_sectors;
4350 
4351 		atomic_inc(&rdev->nr_pending);
4352 		rcu_read_unlock();
4353 		raid_bio->bi_next = (void*)rdev;
4354 		align_bi->bi_bdev =  rdev->bdev;
4355 		__clear_bit(BIO_SEG_VALID, &align_bi->bi_flags);
4356 
4357 		if (!bio_fits_rdev(align_bi) ||
4358 		    is_badblock(rdev, align_bi->bi_iter.bi_sector,
4359 				bio_sectors(align_bi),
4360 				&first_bad, &bad_sectors)) {
4361 			/* too big in some way, or has a known bad block */
4362 			bio_put(align_bi);
4363 			rdev_dec_pending(rdev, mddev);
4364 			return 0;
4365 		}
4366 
4367 		/* No reshape active, so we can trust rdev->data_offset */
4368 		align_bi->bi_iter.bi_sector += rdev->data_offset;
4369 
4370 		spin_lock_irq(&conf->device_lock);
4371 		wait_event_lock_irq(conf->wait_for_stripe,
4372 				    conf->quiesce == 0,
4373 				    conf->device_lock);
4374 		atomic_inc(&conf->active_aligned_reads);
4375 		spin_unlock_irq(&conf->device_lock);
4376 
4377 		if (mddev->gendisk)
4378 			trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4379 					      align_bi, disk_devt(mddev->gendisk),
4380 					      raid_bio->bi_iter.bi_sector);
4381 		generic_make_request(align_bi);
4382 		return 1;
4383 	} else {
4384 		rcu_read_unlock();
4385 		bio_put(align_bi);
4386 		return 0;
4387 	}
4388 }
4389 
4390 /* __get_priority_stripe - get the next stripe to process
4391  *
4392  * Full stripe writes are allowed to pass preread active stripes up until
4393  * the bypass_threshold is exceeded.  In general the bypass_count
4394  * increments when the handle_list is handled before the hold_list; however, it
4395  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4396  * stripe with in flight i/o.  The bypass_count will be reset when the
4397  * head of the hold_list has changed, i.e. the head was promoted to the
4398  * handle_list.
4399  */
4400 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
4401 {
4402 	struct stripe_head *sh = NULL, *tmp;
4403 	struct list_head *handle_list = NULL;
4404 	struct r5worker_group *wg = NULL;
4405 
4406 	if (conf->worker_cnt_per_group == 0) {
4407 		handle_list = &conf->handle_list;
4408 	} else if (group != ANY_GROUP) {
4409 		handle_list = &conf->worker_groups[group].handle_list;
4410 		wg = &conf->worker_groups[group];
4411 	} else {
4412 		int i;
4413 		for (i = 0; i < conf->group_cnt; i++) {
4414 			handle_list = &conf->worker_groups[i].handle_list;
4415 			wg = &conf->worker_groups[i];
4416 			if (!list_empty(handle_list))
4417 				break;
4418 		}
4419 	}
4420 
4421 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4422 		  __func__,
4423 		  list_empty(handle_list) ? "empty" : "busy",
4424 		  list_empty(&conf->hold_list) ? "empty" : "busy",
4425 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
4426 
4427 	if (!list_empty(handle_list)) {
4428 		sh = list_entry(handle_list->next, typeof(*sh), lru);
4429 
4430 		if (list_empty(&conf->hold_list))
4431 			conf->bypass_count = 0;
4432 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4433 			if (conf->hold_list.next == conf->last_hold)
4434 				conf->bypass_count++;
4435 			else {
4436 				conf->last_hold = conf->hold_list.next;
4437 				conf->bypass_count -= conf->bypass_threshold;
4438 				if (conf->bypass_count < 0)
4439 					conf->bypass_count = 0;
4440 			}
4441 		}
4442 	} else if (!list_empty(&conf->hold_list) &&
4443 		   ((conf->bypass_threshold &&
4444 		     conf->bypass_count > conf->bypass_threshold) ||
4445 		    atomic_read(&conf->pending_full_writes) == 0)) {
4446 
4447 		list_for_each_entry(tmp, &conf->hold_list,  lru) {
4448 			if (conf->worker_cnt_per_group == 0 ||
4449 			    group == ANY_GROUP ||
4450 			    !cpu_online(tmp->cpu) ||
4451 			    cpu_to_group(tmp->cpu) == group) {
4452 				sh = tmp;
4453 				break;
4454 			}
4455 		}
4456 
4457 		if (sh) {
4458 			conf->bypass_count -= conf->bypass_threshold;
4459 			if (conf->bypass_count < 0)
4460 				conf->bypass_count = 0;
4461 		}
4462 		wg = NULL;
4463 	}
4464 
4465 	if (!sh)
4466 		return NULL;
4467 
4468 	if (wg) {
4469 		wg->stripes_cnt--;
4470 		sh->group = NULL;
4471 	}
4472 	list_del_init(&sh->lru);
4473 	BUG_ON(atomic_inc_return(&sh->count) != 1);
4474 	return sh;
4475 }
4476 
4477 struct raid5_plug_cb {
4478 	struct blk_plug_cb	cb;
4479 	struct list_head	list;
4480 	struct list_head	temp_inactive_list[NR_STRIPE_HASH_LOCKS];
4481 };
4482 
4483 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4484 {
4485 	struct raid5_plug_cb *cb = container_of(
4486 		blk_cb, struct raid5_plug_cb, cb);
4487 	struct stripe_head *sh;
4488 	struct mddev *mddev = cb->cb.data;
4489 	struct r5conf *conf = mddev->private;
4490 	int cnt = 0;
4491 	int hash;
4492 
4493 	if (cb->list.next && !list_empty(&cb->list)) {
4494 		spin_lock_irq(&conf->device_lock);
4495 		while (!list_empty(&cb->list)) {
4496 			sh = list_first_entry(&cb->list, struct stripe_head, lru);
4497 			list_del_init(&sh->lru);
4498 			/*
4499 			 * avoid race release_stripe_plug() sees
4500 			 * STRIPE_ON_UNPLUG_LIST clear but the stripe
4501 			 * is still in our list
4502 			 */
4503 			smp_mb__before_atomic();
4504 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4505 			/*
4506 			 * STRIPE_ON_RELEASE_LIST could be set here. In that
4507 			 * case, the count is always > 1 here
4508 			 */
4509 			hash = sh->hash_lock_index;
4510 			__release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
4511 			cnt++;
4512 		}
4513 		spin_unlock_irq(&conf->device_lock);
4514 	}
4515 	release_inactive_stripe_list(conf, cb->temp_inactive_list,
4516 				     NR_STRIPE_HASH_LOCKS);
4517 	if (mddev->queue)
4518 		trace_block_unplug(mddev->queue, cnt, !from_schedule);
4519 	kfree(cb);
4520 }
4521 
4522 static void release_stripe_plug(struct mddev *mddev,
4523 				struct stripe_head *sh)
4524 {
4525 	struct blk_plug_cb *blk_cb = blk_check_plugged(
4526 		raid5_unplug, mddev,
4527 		sizeof(struct raid5_plug_cb));
4528 	struct raid5_plug_cb *cb;
4529 
4530 	if (!blk_cb) {
4531 		release_stripe(sh);
4532 		return;
4533 	}
4534 
4535 	cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4536 
4537 	if (cb->list.next == NULL) {
4538 		int i;
4539 		INIT_LIST_HEAD(&cb->list);
4540 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
4541 			INIT_LIST_HEAD(cb->temp_inactive_list + i);
4542 	}
4543 
4544 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4545 		list_add_tail(&sh->lru, &cb->list);
4546 	else
4547 		release_stripe(sh);
4548 }
4549 
4550 static void make_discard_request(struct mddev *mddev, struct bio *bi)
4551 {
4552 	struct r5conf *conf = mddev->private;
4553 	sector_t logical_sector, last_sector;
4554 	struct stripe_head *sh;
4555 	int remaining;
4556 	int stripe_sectors;
4557 
4558 	if (mddev->reshape_position != MaxSector)
4559 		/* Skip discard while reshape is happening */
4560 		return;
4561 
4562 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4563 	last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
4564 
4565 	bi->bi_next = NULL;
4566 	bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4567 
4568 	stripe_sectors = conf->chunk_sectors *
4569 		(conf->raid_disks - conf->max_degraded);
4570 	logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4571 					       stripe_sectors);
4572 	sector_div(last_sector, stripe_sectors);
4573 
4574 	logical_sector *= conf->chunk_sectors;
4575 	last_sector *= conf->chunk_sectors;
4576 
4577 	for (; logical_sector < last_sector;
4578 	     logical_sector += STRIPE_SECTORS) {
4579 		DEFINE_WAIT(w);
4580 		int d;
4581 	again:
4582 		sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4583 		prepare_to_wait(&conf->wait_for_overlap, &w,
4584 				TASK_UNINTERRUPTIBLE);
4585 		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4586 		if (test_bit(STRIPE_SYNCING, &sh->state)) {
4587 			release_stripe(sh);
4588 			schedule();
4589 			goto again;
4590 		}
4591 		clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4592 		spin_lock_irq(&sh->stripe_lock);
4593 		for (d = 0; d < conf->raid_disks; d++) {
4594 			if (d == sh->pd_idx || d == sh->qd_idx)
4595 				continue;
4596 			if (sh->dev[d].towrite || sh->dev[d].toread) {
4597 				set_bit(R5_Overlap, &sh->dev[d].flags);
4598 				spin_unlock_irq(&sh->stripe_lock);
4599 				release_stripe(sh);
4600 				schedule();
4601 				goto again;
4602 			}
4603 		}
4604 		set_bit(STRIPE_DISCARD, &sh->state);
4605 		finish_wait(&conf->wait_for_overlap, &w);
4606 		for (d = 0; d < conf->raid_disks; d++) {
4607 			if (d == sh->pd_idx || d == sh->qd_idx)
4608 				continue;
4609 			sh->dev[d].towrite = bi;
4610 			set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4611 			raid5_inc_bi_active_stripes(bi);
4612 		}
4613 		spin_unlock_irq(&sh->stripe_lock);
4614 		if (conf->mddev->bitmap) {
4615 			for (d = 0;
4616 			     d < conf->raid_disks - conf->max_degraded;
4617 			     d++)
4618 				bitmap_startwrite(mddev->bitmap,
4619 						  sh->sector,
4620 						  STRIPE_SECTORS,
4621 						  0);
4622 			sh->bm_seq = conf->seq_flush + 1;
4623 			set_bit(STRIPE_BIT_DELAY, &sh->state);
4624 		}
4625 
4626 		set_bit(STRIPE_HANDLE, &sh->state);
4627 		clear_bit(STRIPE_DELAYED, &sh->state);
4628 		if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4629 			atomic_inc(&conf->preread_active_stripes);
4630 		release_stripe_plug(mddev, sh);
4631 	}
4632 
4633 	remaining = raid5_dec_bi_active_stripes(bi);
4634 	if (remaining == 0) {
4635 		md_write_end(mddev);
4636 		bio_endio(bi, 0);
4637 	}
4638 }
4639 
4640 static void make_request(struct mddev *mddev, struct bio * bi)
4641 {
4642 	struct r5conf *conf = mddev->private;
4643 	int dd_idx;
4644 	sector_t new_sector;
4645 	sector_t logical_sector, last_sector;
4646 	struct stripe_head *sh;
4647 	const int rw = bio_data_dir(bi);
4648 	int remaining;
4649 	DEFINE_WAIT(w);
4650 	bool do_prepare;
4651 
4652 	if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4653 		md_flush_request(mddev, bi);
4654 		return;
4655 	}
4656 
4657 	md_write_start(mddev, bi);
4658 
4659 	if (rw == READ &&
4660 	     mddev->reshape_position == MaxSector &&
4661 	     chunk_aligned_read(mddev,bi))
4662 		return;
4663 
4664 	if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4665 		make_discard_request(mddev, bi);
4666 		return;
4667 	}
4668 
4669 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4670 	last_sector = bio_end_sector(bi);
4671 	bi->bi_next = NULL;
4672 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
4673 
4674 	prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4675 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4676 		int previous;
4677 		int seq;
4678 
4679 		do_prepare = false;
4680 	retry:
4681 		seq = read_seqcount_begin(&conf->gen_lock);
4682 		previous = 0;
4683 		if (do_prepare)
4684 			prepare_to_wait(&conf->wait_for_overlap, &w,
4685 				TASK_UNINTERRUPTIBLE);
4686 		if (unlikely(conf->reshape_progress != MaxSector)) {
4687 			/* spinlock is needed as reshape_progress may be
4688 			 * 64bit on a 32bit platform, and so it might be
4689 			 * possible to see a half-updated value
4690 			 * Of course reshape_progress could change after
4691 			 * the lock is dropped, so once we get a reference
4692 			 * to the stripe that we think it is, we will have
4693 			 * to check again.
4694 			 */
4695 			spin_lock_irq(&conf->device_lock);
4696 			if (mddev->reshape_backwards
4697 			    ? logical_sector < conf->reshape_progress
4698 			    : logical_sector >= conf->reshape_progress) {
4699 				previous = 1;
4700 			} else {
4701 				if (mddev->reshape_backwards
4702 				    ? logical_sector < conf->reshape_safe
4703 				    : logical_sector >= conf->reshape_safe) {
4704 					spin_unlock_irq(&conf->device_lock);
4705 					schedule();
4706 					do_prepare = true;
4707 					goto retry;
4708 				}
4709 			}
4710 			spin_unlock_irq(&conf->device_lock);
4711 		}
4712 
4713 		new_sector = raid5_compute_sector(conf, logical_sector,
4714 						  previous,
4715 						  &dd_idx, NULL);
4716 		pr_debug("raid456: make_request, sector %llu logical %llu\n",
4717 			(unsigned long long)new_sector,
4718 			(unsigned long long)logical_sector);
4719 
4720 		sh = get_active_stripe(conf, new_sector, previous,
4721 				       (bi->bi_rw&RWA_MASK), 0);
4722 		if (sh) {
4723 			if (unlikely(previous)) {
4724 				/* expansion might have moved on while waiting for a
4725 				 * stripe, so we must do the range check again.
4726 				 * Expansion could still move past after this
4727 				 * test, but as we are holding a reference to
4728 				 * 'sh', we know that if that happens,
4729 				 *  STRIPE_EXPANDING will get set and the expansion
4730 				 * won't proceed until we finish with the stripe.
4731 				 */
4732 				int must_retry = 0;
4733 				spin_lock_irq(&conf->device_lock);
4734 				if (mddev->reshape_backwards
4735 				    ? logical_sector >= conf->reshape_progress
4736 				    : logical_sector < conf->reshape_progress)
4737 					/* mismatch, need to try again */
4738 					must_retry = 1;
4739 				spin_unlock_irq(&conf->device_lock);
4740 				if (must_retry) {
4741 					release_stripe(sh);
4742 					schedule();
4743 					do_prepare = true;
4744 					goto retry;
4745 				}
4746 			}
4747 			if (read_seqcount_retry(&conf->gen_lock, seq)) {
4748 				/* Might have got the wrong stripe_head
4749 				 * by accident
4750 				 */
4751 				release_stripe(sh);
4752 				goto retry;
4753 			}
4754 
4755 			if (rw == WRITE &&
4756 			    logical_sector >= mddev->suspend_lo &&
4757 			    logical_sector < mddev->suspend_hi) {
4758 				release_stripe(sh);
4759 				/* As the suspend_* range is controlled by
4760 				 * userspace, we want an interruptible
4761 				 * wait.
4762 				 */
4763 				flush_signals(current);
4764 				prepare_to_wait(&conf->wait_for_overlap,
4765 						&w, TASK_INTERRUPTIBLE);
4766 				if (logical_sector >= mddev->suspend_lo &&
4767 				    logical_sector < mddev->suspend_hi) {
4768 					schedule();
4769 					do_prepare = true;
4770 				}
4771 				goto retry;
4772 			}
4773 
4774 			if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4775 			    !add_stripe_bio(sh, bi, dd_idx, rw)) {
4776 				/* Stripe is busy expanding or
4777 				 * add failed due to overlap.  Flush everything
4778 				 * and wait a while
4779 				 */
4780 				md_wakeup_thread(mddev->thread);
4781 				release_stripe(sh);
4782 				schedule();
4783 				do_prepare = true;
4784 				goto retry;
4785 			}
4786 			set_bit(STRIPE_HANDLE, &sh->state);
4787 			clear_bit(STRIPE_DELAYED, &sh->state);
4788 			if ((bi->bi_rw & REQ_SYNC) &&
4789 			    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4790 				atomic_inc(&conf->preread_active_stripes);
4791 			release_stripe_plug(mddev, sh);
4792 		} else {
4793 			/* cannot get stripe for read-ahead, just give-up */
4794 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
4795 			break;
4796 		}
4797 	}
4798 	finish_wait(&conf->wait_for_overlap, &w);
4799 
4800 	remaining = raid5_dec_bi_active_stripes(bi);
4801 	if (remaining == 0) {
4802 
4803 		if ( rw == WRITE )
4804 			md_write_end(mddev);
4805 
4806 		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4807 					 bi, 0);
4808 		bio_endio(bi, 0);
4809 	}
4810 }
4811 
4812 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4813 
4814 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4815 {
4816 	/* reshaping is quite different to recovery/resync so it is
4817 	 * handled quite separately ... here.
4818 	 *
4819 	 * On each call to sync_request, we gather one chunk worth of
4820 	 * destination stripes and flag them as expanding.
4821 	 * Then we find all the source stripes and request reads.
4822 	 * As the reads complete, handle_stripe will copy the data
4823 	 * into the destination stripe and release that stripe.
4824 	 */
4825 	struct r5conf *conf = mddev->private;
4826 	struct stripe_head *sh;
4827 	sector_t first_sector, last_sector;
4828 	int raid_disks = conf->previous_raid_disks;
4829 	int data_disks = raid_disks - conf->max_degraded;
4830 	int new_data_disks = conf->raid_disks - conf->max_degraded;
4831 	int i;
4832 	int dd_idx;
4833 	sector_t writepos, readpos, safepos;
4834 	sector_t stripe_addr;
4835 	int reshape_sectors;
4836 	struct list_head stripes;
4837 
4838 	if (sector_nr == 0) {
4839 		/* If restarting in the middle, skip the initial sectors */
4840 		if (mddev->reshape_backwards &&
4841 		    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4842 			sector_nr = raid5_size(mddev, 0, 0)
4843 				- conf->reshape_progress;
4844 		} else if (!mddev->reshape_backwards &&
4845 			   conf->reshape_progress > 0)
4846 			sector_nr = conf->reshape_progress;
4847 		sector_div(sector_nr, new_data_disks);
4848 		if (sector_nr) {
4849 			mddev->curr_resync_completed = sector_nr;
4850 			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4851 			*skipped = 1;
4852 			return sector_nr;
4853 		}
4854 	}
4855 
4856 	/* We need to process a full chunk at a time.
4857 	 * If old and new chunk sizes differ, we need to process the
4858 	 * largest of these
4859 	 */
4860 	if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4861 		reshape_sectors = mddev->new_chunk_sectors;
4862 	else
4863 		reshape_sectors = mddev->chunk_sectors;
4864 
4865 	/* We update the metadata at least every 10 seconds, or when
4866 	 * the data about to be copied would over-write the source of
4867 	 * the data at the front of the range.  i.e. one new_stripe
4868 	 * along from reshape_progress new_maps to after where
4869 	 * reshape_safe old_maps to
4870 	 */
4871 	writepos = conf->reshape_progress;
4872 	sector_div(writepos, new_data_disks);
4873 	readpos = conf->reshape_progress;
4874 	sector_div(readpos, data_disks);
4875 	safepos = conf->reshape_safe;
4876 	sector_div(safepos, data_disks);
4877 	if (mddev->reshape_backwards) {
4878 		writepos -= min_t(sector_t, reshape_sectors, writepos);
4879 		readpos += reshape_sectors;
4880 		safepos += reshape_sectors;
4881 	} else {
4882 		writepos += reshape_sectors;
4883 		readpos -= min_t(sector_t, reshape_sectors, readpos);
4884 		safepos -= min_t(sector_t, reshape_sectors, safepos);
4885 	}
4886 
4887 	/* Having calculated the 'writepos' possibly use it
4888 	 * to set 'stripe_addr' which is where we will write to.
4889 	 */
4890 	if (mddev->reshape_backwards) {
4891 		BUG_ON(conf->reshape_progress == 0);
4892 		stripe_addr = writepos;
4893 		BUG_ON((mddev->dev_sectors &
4894 			~((sector_t)reshape_sectors - 1))
4895 		       - reshape_sectors - stripe_addr
4896 		       != sector_nr);
4897 	} else {
4898 		BUG_ON(writepos != sector_nr + reshape_sectors);
4899 		stripe_addr = sector_nr;
4900 	}
4901 
4902 	/* 'writepos' is the most advanced device address we might write.
4903 	 * 'readpos' is the least advanced device address we might read.
4904 	 * 'safepos' is the least address recorded in the metadata as having
4905 	 *     been reshaped.
4906 	 * If there is a min_offset_diff, these are adjusted either by
4907 	 * increasing the safepos/readpos if diff is negative, or
4908 	 * increasing writepos if diff is positive.
4909 	 * If 'readpos' is then behind 'writepos', there is no way that we can
4910 	 * ensure safety in the face of a crash - that must be done by userspace
4911 	 * making a backup of the data.  So in that case there is no particular
4912 	 * rush to update metadata.
4913 	 * Otherwise if 'safepos' is behind 'writepos', then we really need to
4914 	 * update the metadata to advance 'safepos' to match 'readpos' so that
4915 	 * we can be safe in the event of a crash.
4916 	 * So we insist on updating metadata if safepos is behind writepos and
4917 	 * readpos is beyond writepos.
4918 	 * In any case, update the metadata every 10 seconds.
4919 	 * Maybe that number should be configurable, but I'm not sure it is
4920 	 * worth it.... maybe it could be a multiple of safemode_delay???
4921 	 */
4922 	if (conf->min_offset_diff < 0) {
4923 		safepos += -conf->min_offset_diff;
4924 		readpos += -conf->min_offset_diff;
4925 	} else
4926 		writepos += conf->min_offset_diff;
4927 
4928 	if ((mddev->reshape_backwards
4929 	     ? (safepos > writepos && readpos < writepos)
4930 	     : (safepos < writepos && readpos > writepos)) ||
4931 	    time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4932 		/* Cannot proceed until we've updated the superblock... */
4933 		wait_event(conf->wait_for_overlap,
4934 			   atomic_read(&conf->reshape_stripes)==0
4935 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
4936 		if (atomic_read(&conf->reshape_stripes) != 0)
4937 			return 0;
4938 		mddev->reshape_position = conf->reshape_progress;
4939 		mddev->curr_resync_completed = sector_nr;
4940 		conf->reshape_checkpoint = jiffies;
4941 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
4942 		md_wakeup_thread(mddev->thread);
4943 		wait_event(mddev->sb_wait, mddev->flags == 0 ||
4944 			   test_bit(MD_RECOVERY_INTR, &mddev->recovery));
4945 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
4946 			return 0;
4947 		spin_lock_irq(&conf->device_lock);
4948 		conf->reshape_safe = mddev->reshape_position;
4949 		spin_unlock_irq(&conf->device_lock);
4950 		wake_up(&conf->wait_for_overlap);
4951 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4952 	}
4953 
4954 	INIT_LIST_HEAD(&stripes);
4955 	for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4956 		int j;
4957 		int skipped_disk = 0;
4958 		sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4959 		set_bit(STRIPE_EXPANDING, &sh->state);
4960 		atomic_inc(&conf->reshape_stripes);
4961 		/* If any of this stripe is beyond the end of the old
4962 		 * array, then we need to zero those blocks
4963 		 */
4964 		for (j=sh->disks; j--;) {
4965 			sector_t s;
4966 			if (j == sh->pd_idx)
4967 				continue;
4968 			if (conf->level == 6 &&
4969 			    j == sh->qd_idx)
4970 				continue;
4971 			s = compute_blocknr(sh, j, 0);
4972 			if (s < raid5_size(mddev, 0, 0)) {
4973 				skipped_disk = 1;
4974 				continue;
4975 			}
4976 			memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4977 			set_bit(R5_Expanded, &sh->dev[j].flags);
4978 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
4979 		}
4980 		if (!skipped_disk) {
4981 			set_bit(STRIPE_EXPAND_READY, &sh->state);
4982 			set_bit(STRIPE_HANDLE, &sh->state);
4983 		}
4984 		list_add(&sh->lru, &stripes);
4985 	}
4986 	spin_lock_irq(&conf->device_lock);
4987 	if (mddev->reshape_backwards)
4988 		conf->reshape_progress -= reshape_sectors * new_data_disks;
4989 	else
4990 		conf->reshape_progress += reshape_sectors * new_data_disks;
4991 	spin_unlock_irq(&conf->device_lock);
4992 	/* Ok, those stripe are ready. We can start scheduling
4993 	 * reads on the source stripes.
4994 	 * The source stripes are determined by mapping the first and last
4995 	 * block on the destination stripes.
4996 	 */
4997 	first_sector =
4998 		raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4999 				     1, &dd_idx, NULL);
5000 	last_sector =
5001 		raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5002 					    * new_data_disks - 1),
5003 				     1, &dd_idx, NULL);
5004 	if (last_sector >= mddev->dev_sectors)
5005 		last_sector = mddev->dev_sectors - 1;
5006 	while (first_sector <= last_sector) {
5007 		sh = get_active_stripe(conf, first_sector, 1, 0, 1);
5008 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5009 		set_bit(STRIPE_HANDLE, &sh->state);
5010 		release_stripe(sh);
5011 		first_sector += STRIPE_SECTORS;
5012 	}
5013 	/* Now that the sources are clearly marked, we can release
5014 	 * the destination stripes
5015 	 */
5016 	while (!list_empty(&stripes)) {
5017 		sh = list_entry(stripes.next, struct stripe_head, lru);
5018 		list_del_init(&sh->lru);
5019 		release_stripe(sh);
5020 	}
5021 	/* If this takes us to the resync_max point where we have to pause,
5022 	 * then we need to write out the superblock.
5023 	 */
5024 	sector_nr += reshape_sectors;
5025 	if ((sector_nr - mddev->curr_resync_completed) * 2
5026 	    >= mddev->resync_max - mddev->curr_resync_completed) {
5027 		/* Cannot proceed until we've updated the superblock... */
5028 		wait_event(conf->wait_for_overlap,
5029 			   atomic_read(&conf->reshape_stripes) == 0
5030 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5031 		if (atomic_read(&conf->reshape_stripes) != 0)
5032 			goto ret;
5033 		mddev->reshape_position = conf->reshape_progress;
5034 		mddev->curr_resync_completed = sector_nr;
5035 		conf->reshape_checkpoint = jiffies;
5036 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
5037 		md_wakeup_thread(mddev->thread);
5038 		wait_event(mddev->sb_wait,
5039 			   !test_bit(MD_CHANGE_DEVS, &mddev->flags)
5040 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5041 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5042 			goto ret;
5043 		spin_lock_irq(&conf->device_lock);
5044 		conf->reshape_safe = mddev->reshape_position;
5045 		spin_unlock_irq(&conf->device_lock);
5046 		wake_up(&conf->wait_for_overlap);
5047 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5048 	}
5049 ret:
5050 	return reshape_sectors;
5051 }
5052 
5053 /* FIXME go_faster isn't used */
5054 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
5055 {
5056 	struct r5conf *conf = mddev->private;
5057 	struct stripe_head *sh;
5058 	sector_t max_sector = mddev->dev_sectors;
5059 	sector_t sync_blocks;
5060 	int still_degraded = 0;
5061 	int i;
5062 
5063 	if (sector_nr >= max_sector) {
5064 		/* just being told to finish up .. nothing much to do */
5065 
5066 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5067 			end_reshape(conf);
5068 			return 0;
5069 		}
5070 
5071 		if (mddev->curr_resync < max_sector) /* aborted */
5072 			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5073 					&sync_blocks, 1);
5074 		else /* completed sync */
5075 			conf->fullsync = 0;
5076 		bitmap_close_sync(mddev->bitmap);
5077 
5078 		return 0;
5079 	}
5080 
5081 	/* Allow raid5_quiesce to complete */
5082 	wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5083 
5084 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5085 		return reshape_request(mddev, sector_nr, skipped);
5086 
5087 	/* No need to check resync_max as we never do more than one
5088 	 * stripe, and as resync_max will always be on a chunk boundary,
5089 	 * if the check in md_do_sync didn't fire, there is no chance
5090 	 * of overstepping resync_max here
5091 	 */
5092 
5093 	/* if there is too many failed drives and we are trying
5094 	 * to resync, then assert that we are finished, because there is
5095 	 * nothing we can do.
5096 	 */
5097 	if (mddev->degraded >= conf->max_degraded &&
5098 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5099 		sector_t rv = mddev->dev_sectors - sector_nr;
5100 		*skipped = 1;
5101 		return rv;
5102 	}
5103 	if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5104 	    !conf->fullsync &&
5105 	    !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5106 	    sync_blocks >= STRIPE_SECTORS) {
5107 		/* we can skip this block, and probably more */
5108 		sync_blocks /= STRIPE_SECTORS;
5109 		*skipped = 1;
5110 		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5111 	}
5112 
5113 	bitmap_cond_end_sync(mddev->bitmap, sector_nr);
5114 
5115 	sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
5116 	if (sh == NULL) {
5117 		sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
5118 		/* make sure we don't swamp the stripe cache if someone else
5119 		 * is trying to get access
5120 		 */
5121 		schedule_timeout_uninterruptible(1);
5122 	}
5123 	/* Need to check if array will still be degraded after recovery/resync
5124 	 * We don't need to check the 'failed' flag as when that gets set,
5125 	 * recovery aborts.
5126 	 */
5127 	for (i = 0; i < conf->raid_disks; i++)
5128 		if (conf->disks[i].rdev == NULL)
5129 			still_degraded = 1;
5130 
5131 	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5132 
5133 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5134 	set_bit(STRIPE_HANDLE, &sh->state);
5135 
5136 	release_stripe(sh);
5137 
5138 	return STRIPE_SECTORS;
5139 }
5140 
5141 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5142 {
5143 	/* We may not be able to submit a whole bio at once as there
5144 	 * may not be enough stripe_heads available.
5145 	 * We cannot pre-allocate enough stripe_heads as we may need
5146 	 * more than exist in the cache (if we allow ever large chunks).
5147 	 * So we do one stripe head at a time and record in
5148 	 * ->bi_hw_segments how many have been done.
5149 	 *
5150 	 * We *know* that this entire raid_bio is in one chunk, so
5151 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5152 	 */
5153 	struct stripe_head *sh;
5154 	int dd_idx;
5155 	sector_t sector, logical_sector, last_sector;
5156 	int scnt = 0;
5157 	int remaining;
5158 	int handled = 0;
5159 
5160 	logical_sector = raid_bio->bi_iter.bi_sector &
5161 		~((sector_t)STRIPE_SECTORS-1);
5162 	sector = raid5_compute_sector(conf, logical_sector,
5163 				      0, &dd_idx, NULL);
5164 	last_sector = bio_end_sector(raid_bio);
5165 
5166 	for (; logical_sector < last_sector;
5167 	     logical_sector += STRIPE_SECTORS,
5168 		     sector += STRIPE_SECTORS,
5169 		     scnt++) {
5170 
5171 		if (scnt < raid5_bi_processed_stripes(raid_bio))
5172 			/* already done this stripe */
5173 			continue;
5174 
5175 		sh = get_active_stripe(conf, sector, 0, 1, 1);
5176 
5177 		if (!sh) {
5178 			/* failed to get a stripe - must wait */
5179 			raid5_set_bi_processed_stripes(raid_bio, scnt);
5180 			conf->retry_read_aligned = raid_bio;
5181 			return handled;
5182 		}
5183 
5184 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
5185 			release_stripe(sh);
5186 			raid5_set_bi_processed_stripes(raid_bio, scnt);
5187 			conf->retry_read_aligned = raid_bio;
5188 			return handled;
5189 		}
5190 
5191 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
5192 		handle_stripe(sh);
5193 		release_stripe(sh);
5194 		handled++;
5195 	}
5196 	remaining = raid5_dec_bi_active_stripes(raid_bio);
5197 	if (remaining == 0) {
5198 		trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
5199 					 raid_bio, 0);
5200 		bio_endio(raid_bio, 0);
5201 	}
5202 	if (atomic_dec_and_test(&conf->active_aligned_reads))
5203 		wake_up(&conf->wait_for_stripe);
5204 	return handled;
5205 }
5206 
5207 static int handle_active_stripes(struct r5conf *conf, int group,
5208 				 struct r5worker *worker,
5209 				 struct list_head *temp_inactive_list)
5210 {
5211 	struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
5212 	int i, batch_size = 0, hash;
5213 	bool release_inactive = false;
5214 
5215 	while (batch_size < MAX_STRIPE_BATCH &&
5216 			(sh = __get_priority_stripe(conf, group)) != NULL)
5217 		batch[batch_size++] = sh;
5218 
5219 	if (batch_size == 0) {
5220 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5221 			if (!list_empty(temp_inactive_list + i))
5222 				break;
5223 		if (i == NR_STRIPE_HASH_LOCKS)
5224 			return batch_size;
5225 		release_inactive = true;
5226 	}
5227 	spin_unlock_irq(&conf->device_lock);
5228 
5229 	release_inactive_stripe_list(conf, temp_inactive_list,
5230 				     NR_STRIPE_HASH_LOCKS);
5231 
5232 	if (release_inactive) {
5233 		spin_lock_irq(&conf->device_lock);
5234 		return 0;
5235 	}
5236 
5237 	for (i = 0; i < batch_size; i++)
5238 		handle_stripe(batch[i]);
5239 
5240 	cond_resched();
5241 
5242 	spin_lock_irq(&conf->device_lock);
5243 	for (i = 0; i < batch_size; i++) {
5244 		hash = batch[i]->hash_lock_index;
5245 		__release_stripe(conf, batch[i], &temp_inactive_list[hash]);
5246 	}
5247 	return batch_size;
5248 }
5249 
5250 static void raid5_do_work(struct work_struct *work)
5251 {
5252 	struct r5worker *worker = container_of(work, struct r5worker, work);
5253 	struct r5worker_group *group = worker->group;
5254 	struct r5conf *conf = group->conf;
5255 	int group_id = group - conf->worker_groups;
5256 	int handled;
5257 	struct blk_plug plug;
5258 
5259 	pr_debug("+++ raid5worker active\n");
5260 
5261 	blk_start_plug(&plug);
5262 	handled = 0;
5263 	spin_lock_irq(&conf->device_lock);
5264 	while (1) {
5265 		int batch_size, released;
5266 
5267 		released = release_stripe_list(conf, worker->temp_inactive_list);
5268 
5269 		batch_size = handle_active_stripes(conf, group_id, worker,
5270 						   worker->temp_inactive_list);
5271 		worker->working = false;
5272 		if (!batch_size && !released)
5273 			break;
5274 		handled += batch_size;
5275 	}
5276 	pr_debug("%d stripes handled\n", handled);
5277 
5278 	spin_unlock_irq(&conf->device_lock);
5279 	blk_finish_plug(&plug);
5280 
5281 	pr_debug("--- raid5worker inactive\n");
5282 }
5283 
5284 /*
5285  * This is our raid5 kernel thread.
5286  *
5287  * We scan the hash table for stripes which can be handled now.
5288  * During the scan, completed stripes are saved for us by the interrupt
5289  * handler, so that they will not have to wait for our next wakeup.
5290  */
5291 static void raid5d(struct md_thread *thread)
5292 {
5293 	struct mddev *mddev = thread->mddev;
5294 	struct r5conf *conf = mddev->private;
5295 	int handled;
5296 	struct blk_plug plug;
5297 
5298 	pr_debug("+++ raid5d active\n");
5299 
5300 	md_check_recovery(mddev);
5301 
5302 	blk_start_plug(&plug);
5303 	handled = 0;
5304 	spin_lock_irq(&conf->device_lock);
5305 	while (1) {
5306 		struct bio *bio;
5307 		int batch_size, released;
5308 
5309 		released = release_stripe_list(conf, conf->temp_inactive_list);
5310 
5311 		if (
5312 		    !list_empty(&conf->bitmap_list)) {
5313 			/* Now is a good time to flush some bitmap updates */
5314 			conf->seq_flush++;
5315 			spin_unlock_irq(&conf->device_lock);
5316 			bitmap_unplug(mddev->bitmap);
5317 			spin_lock_irq(&conf->device_lock);
5318 			conf->seq_write = conf->seq_flush;
5319 			activate_bit_delay(conf, conf->temp_inactive_list);
5320 		}
5321 		raid5_activate_delayed(conf);
5322 
5323 		while ((bio = remove_bio_from_retry(conf))) {
5324 			int ok;
5325 			spin_unlock_irq(&conf->device_lock);
5326 			ok = retry_aligned_read(conf, bio);
5327 			spin_lock_irq(&conf->device_lock);
5328 			if (!ok)
5329 				break;
5330 			handled++;
5331 		}
5332 
5333 		batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
5334 						   conf->temp_inactive_list);
5335 		if (!batch_size && !released)
5336 			break;
5337 		handled += batch_size;
5338 
5339 		if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
5340 			spin_unlock_irq(&conf->device_lock);
5341 			md_check_recovery(mddev);
5342 			spin_lock_irq(&conf->device_lock);
5343 		}
5344 	}
5345 	pr_debug("%d stripes handled\n", handled);
5346 
5347 	spin_unlock_irq(&conf->device_lock);
5348 
5349 	async_tx_issue_pending_all();
5350 	blk_finish_plug(&plug);
5351 
5352 	pr_debug("--- raid5d inactive\n");
5353 }
5354 
5355 static ssize_t
5356 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
5357 {
5358 	struct r5conf *conf;
5359 	int ret = 0;
5360 	spin_lock(&mddev->lock);
5361 	conf = mddev->private;
5362 	if (conf)
5363 		ret = sprintf(page, "%d\n", conf->max_nr_stripes);
5364 	spin_unlock(&mddev->lock);
5365 	return ret;
5366 }
5367 
5368 int
5369 raid5_set_cache_size(struct mddev *mddev, int size)
5370 {
5371 	struct r5conf *conf = mddev->private;
5372 	int err;
5373 	int hash;
5374 
5375 	if (size <= 16 || size > 32768)
5376 		return -EINVAL;
5377 	hash = (conf->max_nr_stripes - 1) % NR_STRIPE_HASH_LOCKS;
5378 	while (size < conf->max_nr_stripes) {
5379 		if (drop_one_stripe(conf, hash))
5380 			conf->max_nr_stripes--;
5381 		else
5382 			break;
5383 		hash--;
5384 		if (hash < 0)
5385 			hash = NR_STRIPE_HASH_LOCKS - 1;
5386 	}
5387 	err = md_allow_write(mddev);
5388 	if (err)
5389 		return err;
5390 	hash = conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
5391 	while (size > conf->max_nr_stripes) {
5392 		if (grow_one_stripe(conf, hash))
5393 			conf->max_nr_stripes++;
5394 		else break;
5395 		hash = (hash + 1) % NR_STRIPE_HASH_LOCKS;
5396 	}
5397 	return 0;
5398 }
5399 EXPORT_SYMBOL(raid5_set_cache_size);
5400 
5401 static ssize_t
5402 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
5403 {
5404 	struct r5conf *conf;
5405 	unsigned long new;
5406 	int err;
5407 
5408 	if (len >= PAGE_SIZE)
5409 		return -EINVAL;
5410 	if (kstrtoul(page, 10, &new))
5411 		return -EINVAL;
5412 	err = mddev_lock(mddev);
5413 	if (err)
5414 		return err;
5415 	conf = mddev->private;
5416 	if (!conf)
5417 		err = -ENODEV;
5418 	else
5419 		err = raid5_set_cache_size(mddev, new);
5420 	mddev_unlock(mddev);
5421 
5422 	return err ?: len;
5423 }
5424 
5425 static struct md_sysfs_entry
5426 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
5427 				raid5_show_stripe_cache_size,
5428 				raid5_store_stripe_cache_size);
5429 
5430 static ssize_t
5431 raid5_show_preread_threshold(struct mddev *mddev, char *page)
5432 {
5433 	struct r5conf *conf;
5434 	int ret = 0;
5435 	spin_lock(&mddev->lock);
5436 	conf = mddev->private;
5437 	if (conf)
5438 		ret = sprintf(page, "%d\n", conf->bypass_threshold);
5439 	spin_unlock(&mddev->lock);
5440 	return ret;
5441 }
5442 
5443 static ssize_t
5444 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
5445 {
5446 	struct r5conf *conf;
5447 	unsigned long new;
5448 	int err;
5449 
5450 	if (len >= PAGE_SIZE)
5451 		return -EINVAL;
5452 	if (kstrtoul(page, 10, &new))
5453 		return -EINVAL;
5454 
5455 	err = mddev_lock(mddev);
5456 	if (err)
5457 		return err;
5458 	conf = mddev->private;
5459 	if (!conf)
5460 		err = -ENODEV;
5461 	else if (new > conf->max_nr_stripes)
5462 		err = -EINVAL;
5463 	else
5464 		conf->bypass_threshold = new;
5465 	mddev_unlock(mddev);
5466 	return err ?: len;
5467 }
5468 
5469 static struct md_sysfs_entry
5470 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
5471 					S_IRUGO | S_IWUSR,
5472 					raid5_show_preread_threshold,
5473 					raid5_store_preread_threshold);
5474 
5475 static ssize_t
5476 raid5_show_skip_copy(struct mddev *mddev, char *page)
5477 {
5478 	struct r5conf *conf;
5479 	int ret = 0;
5480 	spin_lock(&mddev->lock);
5481 	conf = mddev->private;
5482 	if (conf)
5483 		ret = sprintf(page, "%d\n", conf->skip_copy);
5484 	spin_unlock(&mddev->lock);
5485 	return ret;
5486 }
5487 
5488 static ssize_t
5489 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
5490 {
5491 	struct r5conf *conf;
5492 	unsigned long new;
5493 	int err;
5494 
5495 	if (len >= PAGE_SIZE)
5496 		return -EINVAL;
5497 	if (kstrtoul(page, 10, &new))
5498 		return -EINVAL;
5499 	new = !!new;
5500 
5501 	err = mddev_lock(mddev);
5502 	if (err)
5503 		return err;
5504 	conf = mddev->private;
5505 	if (!conf)
5506 		err = -ENODEV;
5507 	else if (new != conf->skip_copy) {
5508 		mddev_suspend(mddev);
5509 		conf->skip_copy = new;
5510 		if (new)
5511 			mddev->queue->backing_dev_info.capabilities |=
5512 				BDI_CAP_STABLE_WRITES;
5513 		else
5514 			mddev->queue->backing_dev_info.capabilities &=
5515 				~BDI_CAP_STABLE_WRITES;
5516 		mddev_resume(mddev);
5517 	}
5518 	mddev_unlock(mddev);
5519 	return err ?: len;
5520 }
5521 
5522 static struct md_sysfs_entry
5523 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
5524 					raid5_show_skip_copy,
5525 					raid5_store_skip_copy);
5526 
5527 static ssize_t
5528 stripe_cache_active_show(struct mddev *mddev, char *page)
5529 {
5530 	struct r5conf *conf = mddev->private;
5531 	if (conf)
5532 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
5533 	else
5534 		return 0;
5535 }
5536 
5537 static struct md_sysfs_entry
5538 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
5539 
5540 static ssize_t
5541 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
5542 {
5543 	struct r5conf *conf;
5544 	int ret = 0;
5545 	spin_lock(&mddev->lock);
5546 	conf = mddev->private;
5547 	if (conf)
5548 		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
5549 	spin_unlock(&mddev->lock);
5550 	return ret;
5551 }
5552 
5553 static int alloc_thread_groups(struct r5conf *conf, int cnt,
5554 			       int *group_cnt,
5555 			       int *worker_cnt_per_group,
5556 			       struct r5worker_group **worker_groups);
5557 static ssize_t
5558 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
5559 {
5560 	struct r5conf *conf;
5561 	unsigned long new;
5562 	int err;
5563 	struct r5worker_group *new_groups, *old_groups;
5564 	int group_cnt, worker_cnt_per_group;
5565 
5566 	if (len >= PAGE_SIZE)
5567 		return -EINVAL;
5568 	if (kstrtoul(page, 10, &new))
5569 		return -EINVAL;
5570 
5571 	err = mddev_lock(mddev);
5572 	if (err)
5573 		return err;
5574 	conf = mddev->private;
5575 	if (!conf)
5576 		err = -ENODEV;
5577 	else if (new != conf->worker_cnt_per_group) {
5578 		mddev_suspend(mddev);
5579 
5580 		old_groups = conf->worker_groups;
5581 		if (old_groups)
5582 			flush_workqueue(raid5_wq);
5583 
5584 		err = alloc_thread_groups(conf, new,
5585 					  &group_cnt, &worker_cnt_per_group,
5586 					  &new_groups);
5587 		if (!err) {
5588 			spin_lock_irq(&conf->device_lock);
5589 			conf->group_cnt = group_cnt;
5590 			conf->worker_cnt_per_group = worker_cnt_per_group;
5591 			conf->worker_groups = new_groups;
5592 			spin_unlock_irq(&conf->device_lock);
5593 
5594 			if (old_groups)
5595 				kfree(old_groups[0].workers);
5596 			kfree(old_groups);
5597 		}
5598 		mddev_resume(mddev);
5599 	}
5600 	mddev_unlock(mddev);
5601 
5602 	return err ?: len;
5603 }
5604 
5605 static struct md_sysfs_entry
5606 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
5607 				raid5_show_group_thread_cnt,
5608 				raid5_store_group_thread_cnt);
5609 
5610 static struct attribute *raid5_attrs[] =  {
5611 	&raid5_stripecache_size.attr,
5612 	&raid5_stripecache_active.attr,
5613 	&raid5_preread_bypass_threshold.attr,
5614 	&raid5_group_thread_cnt.attr,
5615 	&raid5_skip_copy.attr,
5616 	NULL,
5617 };
5618 static struct attribute_group raid5_attrs_group = {
5619 	.name = NULL,
5620 	.attrs = raid5_attrs,
5621 };
5622 
5623 static int alloc_thread_groups(struct r5conf *conf, int cnt,
5624 			       int *group_cnt,
5625 			       int *worker_cnt_per_group,
5626 			       struct r5worker_group **worker_groups)
5627 {
5628 	int i, j, k;
5629 	ssize_t size;
5630 	struct r5worker *workers;
5631 
5632 	*worker_cnt_per_group = cnt;
5633 	if (cnt == 0) {
5634 		*group_cnt = 0;
5635 		*worker_groups = NULL;
5636 		return 0;
5637 	}
5638 	*group_cnt = num_possible_nodes();
5639 	size = sizeof(struct r5worker) * cnt;
5640 	workers = kzalloc(size * *group_cnt, GFP_NOIO);
5641 	*worker_groups = kzalloc(sizeof(struct r5worker_group) *
5642 				*group_cnt, GFP_NOIO);
5643 	if (!*worker_groups || !workers) {
5644 		kfree(workers);
5645 		kfree(*worker_groups);
5646 		return -ENOMEM;
5647 	}
5648 
5649 	for (i = 0; i < *group_cnt; i++) {
5650 		struct r5worker_group *group;
5651 
5652 		group = &(*worker_groups)[i];
5653 		INIT_LIST_HEAD(&group->handle_list);
5654 		group->conf = conf;
5655 		group->workers = workers + i * cnt;
5656 
5657 		for (j = 0; j < cnt; j++) {
5658 			struct r5worker *worker = group->workers + j;
5659 			worker->group = group;
5660 			INIT_WORK(&worker->work, raid5_do_work);
5661 
5662 			for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
5663 				INIT_LIST_HEAD(worker->temp_inactive_list + k);
5664 		}
5665 	}
5666 
5667 	return 0;
5668 }
5669 
5670 static void free_thread_groups(struct r5conf *conf)
5671 {
5672 	if (conf->worker_groups)
5673 		kfree(conf->worker_groups[0].workers);
5674 	kfree(conf->worker_groups);
5675 	conf->worker_groups = NULL;
5676 }
5677 
5678 static sector_t
5679 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
5680 {
5681 	struct r5conf *conf = mddev->private;
5682 
5683 	if (!sectors)
5684 		sectors = mddev->dev_sectors;
5685 	if (!raid_disks)
5686 		/* size is defined by the smallest of previous and new size */
5687 		raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
5688 
5689 	sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5690 	sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
5691 	return sectors * (raid_disks - conf->max_degraded);
5692 }
5693 
5694 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
5695 {
5696 	safe_put_page(percpu->spare_page);
5697 	kfree(percpu->scribble);
5698 	percpu->spare_page = NULL;
5699 	percpu->scribble = NULL;
5700 }
5701 
5702 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
5703 {
5704 	if (conf->level == 6 && !percpu->spare_page)
5705 		percpu->spare_page = alloc_page(GFP_KERNEL);
5706 	if (!percpu->scribble)
5707 		percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5708 
5709 	if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
5710 		free_scratch_buffer(conf, percpu);
5711 		return -ENOMEM;
5712 	}
5713 
5714 	return 0;
5715 }
5716 
5717 static void raid5_free_percpu(struct r5conf *conf)
5718 {
5719 	unsigned long cpu;
5720 
5721 	if (!conf->percpu)
5722 		return;
5723 
5724 #ifdef CONFIG_HOTPLUG_CPU
5725 	unregister_cpu_notifier(&conf->cpu_notify);
5726 #endif
5727 
5728 	get_online_cpus();
5729 	for_each_possible_cpu(cpu)
5730 		free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5731 	put_online_cpus();
5732 
5733 	free_percpu(conf->percpu);
5734 }
5735 
5736 static void free_conf(struct r5conf *conf)
5737 {
5738 	free_thread_groups(conf);
5739 	shrink_stripes(conf);
5740 	raid5_free_percpu(conf);
5741 	kfree(conf->disks);
5742 	kfree(conf->stripe_hashtbl);
5743 	kfree(conf);
5744 }
5745 
5746 #ifdef CONFIG_HOTPLUG_CPU
5747 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
5748 			      void *hcpu)
5749 {
5750 	struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
5751 	long cpu = (long)hcpu;
5752 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
5753 
5754 	switch (action) {
5755 	case CPU_UP_PREPARE:
5756 	case CPU_UP_PREPARE_FROZEN:
5757 		if (alloc_scratch_buffer(conf, percpu)) {
5758 			pr_err("%s: failed memory allocation for cpu%ld\n",
5759 			       __func__, cpu);
5760 			return notifier_from_errno(-ENOMEM);
5761 		}
5762 		break;
5763 	case CPU_DEAD:
5764 	case CPU_DEAD_FROZEN:
5765 		free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5766 		break;
5767 	default:
5768 		break;
5769 	}
5770 	return NOTIFY_OK;
5771 }
5772 #endif
5773 
5774 static int raid5_alloc_percpu(struct r5conf *conf)
5775 {
5776 	unsigned long cpu;
5777 	int err = 0;
5778 
5779 	conf->percpu = alloc_percpu(struct raid5_percpu);
5780 	if (!conf->percpu)
5781 		return -ENOMEM;
5782 
5783 #ifdef CONFIG_HOTPLUG_CPU
5784 	conf->cpu_notify.notifier_call = raid456_cpu_notify;
5785 	conf->cpu_notify.priority = 0;
5786 	err = register_cpu_notifier(&conf->cpu_notify);
5787 	if (err)
5788 		return err;
5789 #endif
5790 
5791 	get_online_cpus();
5792 	for_each_present_cpu(cpu) {
5793 		err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5794 		if (err) {
5795 			pr_err("%s: failed memory allocation for cpu%ld\n",
5796 			       __func__, cpu);
5797 			break;
5798 		}
5799 	}
5800 	put_online_cpus();
5801 
5802 	return err;
5803 }
5804 
5805 static struct r5conf *setup_conf(struct mddev *mddev)
5806 {
5807 	struct r5conf *conf;
5808 	int raid_disk, memory, max_disks;
5809 	struct md_rdev *rdev;
5810 	struct disk_info *disk;
5811 	char pers_name[6];
5812 	int i;
5813 	int group_cnt, worker_cnt_per_group;
5814 	struct r5worker_group *new_group;
5815 
5816 	if (mddev->new_level != 5
5817 	    && mddev->new_level != 4
5818 	    && mddev->new_level != 6) {
5819 		printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
5820 		       mdname(mddev), mddev->new_level);
5821 		return ERR_PTR(-EIO);
5822 	}
5823 	if ((mddev->new_level == 5
5824 	     && !algorithm_valid_raid5(mddev->new_layout)) ||
5825 	    (mddev->new_level == 6
5826 	     && !algorithm_valid_raid6(mddev->new_layout))) {
5827 		printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
5828 		       mdname(mddev), mddev->new_layout);
5829 		return ERR_PTR(-EIO);
5830 	}
5831 	if (mddev->new_level == 6 && mddev->raid_disks < 4) {
5832 		printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
5833 		       mdname(mddev), mddev->raid_disks);
5834 		return ERR_PTR(-EINVAL);
5835 	}
5836 
5837 	if (!mddev->new_chunk_sectors ||
5838 	    (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
5839 	    !is_power_of_2(mddev->new_chunk_sectors)) {
5840 		printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
5841 		       mdname(mddev), mddev->new_chunk_sectors << 9);
5842 		return ERR_PTR(-EINVAL);
5843 	}
5844 
5845 	conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
5846 	if (conf == NULL)
5847 		goto abort;
5848 	/* Don't enable multi-threading by default*/
5849 	if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
5850 				 &new_group)) {
5851 		conf->group_cnt = group_cnt;
5852 		conf->worker_cnt_per_group = worker_cnt_per_group;
5853 		conf->worker_groups = new_group;
5854 	} else
5855 		goto abort;
5856 	spin_lock_init(&conf->device_lock);
5857 	seqcount_init(&conf->gen_lock);
5858 	init_waitqueue_head(&conf->wait_for_stripe);
5859 	init_waitqueue_head(&conf->wait_for_overlap);
5860 	INIT_LIST_HEAD(&conf->handle_list);
5861 	INIT_LIST_HEAD(&conf->hold_list);
5862 	INIT_LIST_HEAD(&conf->delayed_list);
5863 	INIT_LIST_HEAD(&conf->bitmap_list);
5864 	init_llist_head(&conf->released_stripes);
5865 	atomic_set(&conf->active_stripes, 0);
5866 	atomic_set(&conf->preread_active_stripes, 0);
5867 	atomic_set(&conf->active_aligned_reads, 0);
5868 	conf->bypass_threshold = BYPASS_THRESHOLD;
5869 	conf->recovery_disabled = mddev->recovery_disabled - 1;
5870 
5871 	conf->raid_disks = mddev->raid_disks;
5872 	if (mddev->reshape_position == MaxSector)
5873 		conf->previous_raid_disks = mddev->raid_disks;
5874 	else
5875 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
5876 	max_disks = max(conf->raid_disks, conf->previous_raid_disks);
5877 	conf->scribble_len = scribble_len(max_disks);
5878 
5879 	conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
5880 			      GFP_KERNEL);
5881 	if (!conf->disks)
5882 		goto abort;
5883 
5884 	conf->mddev = mddev;
5885 
5886 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
5887 		goto abort;
5888 
5889 	/* We init hash_locks[0] separately to that it can be used
5890 	 * as the reference lock in the spin_lock_nest_lock() call
5891 	 * in lock_all_device_hash_locks_irq in order to convince
5892 	 * lockdep that we know what we are doing.
5893 	 */
5894 	spin_lock_init(conf->hash_locks);
5895 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
5896 		spin_lock_init(conf->hash_locks + i);
5897 
5898 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5899 		INIT_LIST_HEAD(conf->inactive_list + i);
5900 
5901 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5902 		INIT_LIST_HEAD(conf->temp_inactive_list + i);
5903 
5904 	conf->level = mddev->new_level;
5905 	if (raid5_alloc_percpu(conf) != 0)
5906 		goto abort;
5907 
5908 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
5909 
5910 	rdev_for_each(rdev, mddev) {
5911 		raid_disk = rdev->raid_disk;
5912 		if (raid_disk >= max_disks
5913 		    || raid_disk < 0)
5914 			continue;
5915 		disk = conf->disks + raid_disk;
5916 
5917 		if (test_bit(Replacement, &rdev->flags)) {
5918 			if (disk->replacement)
5919 				goto abort;
5920 			disk->replacement = rdev;
5921 		} else {
5922 			if (disk->rdev)
5923 				goto abort;
5924 			disk->rdev = rdev;
5925 		}
5926 
5927 		if (test_bit(In_sync, &rdev->flags)) {
5928 			char b[BDEVNAME_SIZE];
5929 			printk(KERN_INFO "md/raid:%s: device %s operational as raid"
5930 			       " disk %d\n",
5931 			       mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
5932 		} else if (rdev->saved_raid_disk != raid_disk)
5933 			/* Cannot rely on bitmap to complete recovery */
5934 			conf->fullsync = 1;
5935 	}
5936 
5937 	conf->chunk_sectors = mddev->new_chunk_sectors;
5938 	conf->level = mddev->new_level;
5939 	if (conf->level == 6)
5940 		conf->max_degraded = 2;
5941 	else
5942 		conf->max_degraded = 1;
5943 	conf->algorithm = mddev->new_layout;
5944 	conf->reshape_progress = mddev->reshape_position;
5945 	if (conf->reshape_progress != MaxSector) {
5946 		conf->prev_chunk_sectors = mddev->chunk_sectors;
5947 		conf->prev_algo = mddev->layout;
5948 	}
5949 
5950 	memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
5951 		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
5952 	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
5953 	if (grow_stripes(conf, NR_STRIPES)) {
5954 		printk(KERN_ERR
5955 		       "md/raid:%s: couldn't allocate %dkB for buffers\n",
5956 		       mdname(mddev), memory);
5957 		goto abort;
5958 	} else
5959 		printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
5960 		       mdname(mddev), memory);
5961 
5962 	sprintf(pers_name, "raid%d", mddev->new_level);
5963 	conf->thread = md_register_thread(raid5d, mddev, pers_name);
5964 	if (!conf->thread) {
5965 		printk(KERN_ERR
5966 		       "md/raid:%s: couldn't allocate thread.\n",
5967 		       mdname(mddev));
5968 		goto abort;
5969 	}
5970 
5971 	return conf;
5972 
5973  abort:
5974 	if (conf) {
5975 		free_conf(conf);
5976 		return ERR_PTR(-EIO);
5977 	} else
5978 		return ERR_PTR(-ENOMEM);
5979 }
5980 
5981 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
5982 {
5983 	switch (algo) {
5984 	case ALGORITHM_PARITY_0:
5985 		if (raid_disk < max_degraded)
5986 			return 1;
5987 		break;
5988 	case ALGORITHM_PARITY_N:
5989 		if (raid_disk >= raid_disks - max_degraded)
5990 			return 1;
5991 		break;
5992 	case ALGORITHM_PARITY_0_6:
5993 		if (raid_disk == 0 ||
5994 		    raid_disk == raid_disks - 1)
5995 			return 1;
5996 		break;
5997 	case ALGORITHM_LEFT_ASYMMETRIC_6:
5998 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
5999 	case ALGORITHM_LEFT_SYMMETRIC_6:
6000 	case ALGORITHM_RIGHT_SYMMETRIC_6:
6001 		if (raid_disk == raid_disks - 1)
6002 			return 1;
6003 	}
6004 	return 0;
6005 }
6006 
6007 static int run(struct mddev *mddev)
6008 {
6009 	struct r5conf *conf;
6010 	int working_disks = 0;
6011 	int dirty_parity_disks = 0;
6012 	struct md_rdev *rdev;
6013 	sector_t reshape_offset = 0;
6014 	int i;
6015 	long long min_offset_diff = 0;
6016 	int first = 1;
6017 
6018 	if (mddev->recovery_cp != MaxSector)
6019 		printk(KERN_NOTICE "md/raid:%s: not clean"
6020 		       " -- starting background reconstruction\n",
6021 		       mdname(mddev));
6022 
6023 	rdev_for_each(rdev, mddev) {
6024 		long long diff;
6025 		if (rdev->raid_disk < 0)
6026 			continue;
6027 		diff = (rdev->new_data_offset - rdev->data_offset);
6028 		if (first) {
6029 			min_offset_diff = diff;
6030 			first = 0;
6031 		} else if (mddev->reshape_backwards &&
6032 			 diff < min_offset_diff)
6033 			min_offset_diff = diff;
6034 		else if (!mddev->reshape_backwards &&
6035 			 diff > min_offset_diff)
6036 			min_offset_diff = diff;
6037 	}
6038 
6039 	if (mddev->reshape_position != MaxSector) {
6040 		/* Check that we can continue the reshape.
6041 		 * Difficulties arise if the stripe we would write to
6042 		 * next is at or after the stripe we would read from next.
6043 		 * For a reshape that changes the number of devices, this
6044 		 * is only possible for a very short time, and mdadm makes
6045 		 * sure that time appears to have past before assembling
6046 		 * the array.  So we fail if that time hasn't passed.
6047 		 * For a reshape that keeps the number of devices the same
6048 		 * mdadm must be monitoring the reshape can keeping the
6049 		 * critical areas read-only and backed up.  It will start
6050 		 * the array in read-only mode, so we check for that.
6051 		 */
6052 		sector_t here_new, here_old;
6053 		int old_disks;
6054 		int max_degraded = (mddev->level == 6 ? 2 : 1);
6055 
6056 		if (mddev->new_level != mddev->level) {
6057 			printk(KERN_ERR "md/raid:%s: unsupported reshape "
6058 			       "required - aborting.\n",
6059 			       mdname(mddev));
6060 			return -EINVAL;
6061 		}
6062 		old_disks = mddev->raid_disks - mddev->delta_disks;
6063 		/* reshape_position must be on a new-stripe boundary, and one
6064 		 * further up in new geometry must map after here in old
6065 		 * geometry.
6066 		 */
6067 		here_new = mddev->reshape_position;
6068 		if (sector_div(here_new, mddev->new_chunk_sectors *
6069 			       (mddev->raid_disks - max_degraded))) {
6070 			printk(KERN_ERR "md/raid:%s: reshape_position not "
6071 			       "on a stripe boundary\n", mdname(mddev));
6072 			return -EINVAL;
6073 		}
6074 		reshape_offset = here_new * mddev->new_chunk_sectors;
6075 		/* here_new is the stripe we will write to */
6076 		here_old = mddev->reshape_position;
6077 		sector_div(here_old, mddev->chunk_sectors *
6078 			   (old_disks-max_degraded));
6079 		/* here_old is the first stripe that we might need to read
6080 		 * from */
6081 		if (mddev->delta_disks == 0) {
6082 			if ((here_new * mddev->new_chunk_sectors !=
6083 			     here_old * mddev->chunk_sectors)) {
6084 				printk(KERN_ERR "md/raid:%s: reshape position is"
6085 				       " confused - aborting\n", mdname(mddev));
6086 				return -EINVAL;
6087 			}
6088 			/* We cannot be sure it is safe to start an in-place
6089 			 * reshape.  It is only safe if user-space is monitoring
6090 			 * and taking constant backups.
6091 			 * mdadm always starts a situation like this in
6092 			 * readonly mode so it can take control before
6093 			 * allowing any writes.  So just check for that.
6094 			 */
6095 			if (abs(min_offset_diff) >= mddev->chunk_sectors &&
6096 			    abs(min_offset_diff) >= mddev->new_chunk_sectors)
6097 				/* not really in-place - so OK */;
6098 			else if (mddev->ro == 0) {
6099 				printk(KERN_ERR "md/raid:%s: in-place reshape "
6100 				       "must be started in read-only mode "
6101 				       "- aborting\n",
6102 				       mdname(mddev));
6103 				return -EINVAL;
6104 			}
6105 		} else if (mddev->reshape_backwards
6106 		    ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=
6107 		       here_old * mddev->chunk_sectors)
6108 		    : (here_new * mddev->new_chunk_sectors >=
6109 		       here_old * mddev->chunk_sectors + (-min_offset_diff))) {
6110 			/* Reading from the same stripe as writing to - bad */
6111 			printk(KERN_ERR "md/raid:%s: reshape_position too early for "
6112 			       "auto-recovery - aborting.\n",
6113 			       mdname(mddev));
6114 			return -EINVAL;
6115 		}
6116 		printk(KERN_INFO "md/raid:%s: reshape will continue\n",
6117 		       mdname(mddev));
6118 		/* OK, we should be able to continue; */
6119 	} else {
6120 		BUG_ON(mddev->level != mddev->new_level);
6121 		BUG_ON(mddev->layout != mddev->new_layout);
6122 		BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
6123 		BUG_ON(mddev->delta_disks != 0);
6124 	}
6125 
6126 	if (mddev->private == NULL)
6127 		conf = setup_conf(mddev);
6128 	else
6129 		conf = mddev->private;
6130 
6131 	if (IS_ERR(conf))
6132 		return PTR_ERR(conf);
6133 
6134 	conf->min_offset_diff = min_offset_diff;
6135 	mddev->thread = conf->thread;
6136 	conf->thread = NULL;
6137 	mddev->private = conf;
6138 
6139 	for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
6140 	     i++) {
6141 		rdev = conf->disks[i].rdev;
6142 		if (!rdev && conf->disks[i].replacement) {
6143 			/* The replacement is all we have yet */
6144 			rdev = conf->disks[i].replacement;
6145 			conf->disks[i].replacement = NULL;
6146 			clear_bit(Replacement, &rdev->flags);
6147 			conf->disks[i].rdev = rdev;
6148 		}
6149 		if (!rdev)
6150 			continue;
6151 		if (conf->disks[i].replacement &&
6152 		    conf->reshape_progress != MaxSector) {
6153 			/* replacements and reshape simply do not mix. */
6154 			printk(KERN_ERR "md: cannot handle concurrent "
6155 			       "replacement and reshape.\n");
6156 			goto abort;
6157 		}
6158 		if (test_bit(In_sync, &rdev->flags)) {
6159 			working_disks++;
6160 			continue;
6161 		}
6162 		/* This disc is not fully in-sync.  However if it
6163 		 * just stored parity (beyond the recovery_offset),
6164 		 * when we don't need to be concerned about the
6165 		 * array being dirty.
6166 		 * When reshape goes 'backwards', we never have
6167 		 * partially completed devices, so we only need
6168 		 * to worry about reshape going forwards.
6169 		 */
6170 		/* Hack because v0.91 doesn't store recovery_offset properly. */
6171 		if (mddev->major_version == 0 &&
6172 		    mddev->minor_version > 90)
6173 			rdev->recovery_offset = reshape_offset;
6174 
6175 		if (rdev->recovery_offset < reshape_offset) {
6176 			/* We need to check old and new layout */
6177 			if (!only_parity(rdev->raid_disk,
6178 					 conf->algorithm,
6179 					 conf->raid_disks,
6180 					 conf->max_degraded))
6181 				continue;
6182 		}
6183 		if (!only_parity(rdev->raid_disk,
6184 				 conf->prev_algo,
6185 				 conf->previous_raid_disks,
6186 				 conf->max_degraded))
6187 			continue;
6188 		dirty_parity_disks++;
6189 	}
6190 
6191 	/*
6192 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
6193 	 */
6194 	mddev->degraded = calc_degraded(conf);
6195 
6196 	if (has_failed(conf)) {
6197 		printk(KERN_ERR "md/raid:%s: not enough operational devices"
6198 			" (%d/%d failed)\n",
6199 			mdname(mddev), mddev->degraded, conf->raid_disks);
6200 		goto abort;
6201 	}
6202 
6203 	/* device size must be a multiple of chunk size */
6204 	mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
6205 	mddev->resync_max_sectors = mddev->dev_sectors;
6206 
6207 	if (mddev->degraded > dirty_parity_disks &&
6208 	    mddev->recovery_cp != MaxSector) {
6209 		if (mddev->ok_start_degraded)
6210 			printk(KERN_WARNING
6211 			       "md/raid:%s: starting dirty degraded array"
6212 			       " - data corruption possible.\n",
6213 			       mdname(mddev));
6214 		else {
6215 			printk(KERN_ERR
6216 			       "md/raid:%s: cannot start dirty degraded array.\n",
6217 			       mdname(mddev));
6218 			goto abort;
6219 		}
6220 	}
6221 
6222 	if (mddev->degraded == 0)
6223 		printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
6224 		       " devices, algorithm %d\n", mdname(mddev), conf->level,
6225 		       mddev->raid_disks-mddev->degraded, mddev->raid_disks,
6226 		       mddev->new_layout);
6227 	else
6228 		printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
6229 		       " out of %d devices, algorithm %d\n",
6230 		       mdname(mddev), conf->level,
6231 		       mddev->raid_disks - mddev->degraded,
6232 		       mddev->raid_disks, mddev->new_layout);
6233 
6234 	print_raid5_conf(conf);
6235 
6236 	if (conf->reshape_progress != MaxSector) {
6237 		conf->reshape_safe = conf->reshape_progress;
6238 		atomic_set(&conf->reshape_stripes, 0);
6239 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6240 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6241 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6242 		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6243 		mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6244 							"reshape");
6245 	}
6246 
6247 	/* Ok, everything is just fine now */
6248 	if (mddev->to_remove == &raid5_attrs_group)
6249 		mddev->to_remove = NULL;
6250 	else if (mddev->kobj.sd &&
6251 	    sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
6252 		printk(KERN_WARNING
6253 		       "raid5: failed to create sysfs attributes for %s\n",
6254 		       mdname(mddev));
6255 	md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6256 
6257 	if (mddev->queue) {
6258 		int chunk_size;
6259 		bool discard_supported = true;
6260 		/* read-ahead size must cover two whole stripes, which
6261 		 * is 2 * (datadisks) * chunksize where 'n' is the
6262 		 * number of raid devices
6263 		 */
6264 		int data_disks = conf->previous_raid_disks - conf->max_degraded;
6265 		int stripe = data_disks *
6266 			((mddev->chunk_sectors << 9) / PAGE_SIZE);
6267 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6268 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6269 
6270 		chunk_size = mddev->chunk_sectors << 9;
6271 		blk_queue_io_min(mddev->queue, chunk_size);
6272 		blk_queue_io_opt(mddev->queue, chunk_size *
6273 				 (conf->raid_disks - conf->max_degraded));
6274 		mddev->queue->limits.raid_partial_stripes_expensive = 1;
6275 		/*
6276 		 * We can only discard a whole stripe. It doesn't make sense to
6277 		 * discard data disk but write parity disk
6278 		 */
6279 		stripe = stripe * PAGE_SIZE;
6280 		/* Round up to power of 2, as discard handling
6281 		 * currently assumes that */
6282 		while ((stripe-1) & stripe)
6283 			stripe = (stripe | (stripe-1)) + 1;
6284 		mddev->queue->limits.discard_alignment = stripe;
6285 		mddev->queue->limits.discard_granularity = stripe;
6286 		/*
6287 		 * unaligned part of discard request will be ignored, so can't
6288 		 * guarantee discard_zeroes_data
6289 		 */
6290 		mddev->queue->limits.discard_zeroes_data = 0;
6291 
6292 		blk_queue_max_write_same_sectors(mddev->queue, 0);
6293 
6294 		rdev_for_each(rdev, mddev) {
6295 			disk_stack_limits(mddev->gendisk, rdev->bdev,
6296 					  rdev->data_offset << 9);
6297 			disk_stack_limits(mddev->gendisk, rdev->bdev,
6298 					  rdev->new_data_offset << 9);
6299 			/*
6300 			 * discard_zeroes_data is required, otherwise data
6301 			 * could be lost. Consider a scenario: discard a stripe
6302 			 * (the stripe could be inconsistent if
6303 			 * discard_zeroes_data is 0); write one disk of the
6304 			 * stripe (the stripe could be inconsistent again
6305 			 * depending on which disks are used to calculate
6306 			 * parity); the disk is broken; The stripe data of this
6307 			 * disk is lost.
6308 			 */
6309 			if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
6310 			    !bdev_get_queue(rdev->bdev)->
6311 						limits.discard_zeroes_data)
6312 				discard_supported = false;
6313 			/* Unfortunately, discard_zeroes_data is not currently
6314 			 * a guarantee - just a hint.  So we only allow DISCARD
6315 			 * if the sysadmin has confirmed that only safe devices
6316 			 * are in use by setting a module parameter.
6317 			 */
6318 			if (!devices_handle_discard_safely) {
6319 				if (discard_supported) {
6320 					pr_info("md/raid456: discard support disabled due to uncertainty.\n");
6321 					pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
6322 				}
6323 				discard_supported = false;
6324 			}
6325 		}
6326 
6327 		if (discard_supported &&
6328 		   mddev->queue->limits.max_discard_sectors >= stripe &&
6329 		   mddev->queue->limits.discard_granularity >= stripe)
6330 			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
6331 						mddev->queue);
6332 		else
6333 			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
6334 						mddev->queue);
6335 	}
6336 
6337 	return 0;
6338 abort:
6339 	md_unregister_thread(&mddev->thread);
6340 	print_raid5_conf(conf);
6341 	free_conf(conf);
6342 	mddev->private = NULL;
6343 	printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
6344 	return -EIO;
6345 }
6346 
6347 static void raid5_free(struct mddev *mddev, void *priv)
6348 {
6349 	struct r5conf *conf = priv;
6350 
6351 	free_conf(conf);
6352 	mddev->to_remove = &raid5_attrs_group;
6353 }
6354 
6355 static void status(struct seq_file *seq, struct mddev *mddev)
6356 {
6357 	struct r5conf *conf = mddev->private;
6358 	int i;
6359 
6360 	seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
6361 		mddev->chunk_sectors / 2, mddev->layout);
6362 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
6363 	for (i = 0; i < conf->raid_disks; i++)
6364 		seq_printf (seq, "%s",
6365 			       conf->disks[i].rdev &&
6366 			       test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
6367 	seq_printf (seq, "]");
6368 }
6369 
6370 static void print_raid5_conf (struct r5conf *conf)
6371 {
6372 	int i;
6373 	struct disk_info *tmp;
6374 
6375 	printk(KERN_DEBUG "RAID conf printout:\n");
6376 	if (!conf) {
6377 		printk("(conf==NULL)\n");
6378 		return;
6379 	}
6380 	printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
6381 	       conf->raid_disks,
6382 	       conf->raid_disks - conf->mddev->degraded);
6383 
6384 	for (i = 0; i < conf->raid_disks; i++) {
6385 		char b[BDEVNAME_SIZE];
6386 		tmp = conf->disks + i;
6387 		if (tmp->rdev)
6388 			printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
6389 			       i, !test_bit(Faulty, &tmp->rdev->flags),
6390 			       bdevname(tmp->rdev->bdev, b));
6391 	}
6392 }
6393 
6394 static int raid5_spare_active(struct mddev *mddev)
6395 {
6396 	int i;
6397 	struct r5conf *conf = mddev->private;
6398 	struct disk_info *tmp;
6399 	int count = 0;
6400 	unsigned long flags;
6401 
6402 	for (i = 0; i < conf->raid_disks; i++) {
6403 		tmp = conf->disks + i;
6404 		if (tmp->replacement
6405 		    && tmp->replacement->recovery_offset == MaxSector
6406 		    && !test_bit(Faulty, &tmp->replacement->flags)
6407 		    && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
6408 			/* Replacement has just become active. */
6409 			if (!tmp->rdev
6410 			    || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
6411 				count++;
6412 			if (tmp->rdev) {
6413 				/* Replaced device not technically faulty,
6414 				 * but we need to be sure it gets removed
6415 				 * and never re-added.
6416 				 */
6417 				set_bit(Faulty, &tmp->rdev->flags);
6418 				sysfs_notify_dirent_safe(
6419 					tmp->rdev->sysfs_state);
6420 			}
6421 			sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
6422 		} else if (tmp->rdev
6423 		    && tmp->rdev->recovery_offset == MaxSector
6424 		    && !test_bit(Faulty, &tmp->rdev->flags)
6425 		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
6426 			count++;
6427 			sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
6428 		}
6429 	}
6430 	spin_lock_irqsave(&conf->device_lock, flags);
6431 	mddev->degraded = calc_degraded(conf);
6432 	spin_unlock_irqrestore(&conf->device_lock, flags);
6433 	print_raid5_conf(conf);
6434 	return count;
6435 }
6436 
6437 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
6438 {
6439 	struct r5conf *conf = mddev->private;
6440 	int err = 0;
6441 	int number = rdev->raid_disk;
6442 	struct md_rdev **rdevp;
6443 	struct disk_info *p = conf->disks + number;
6444 
6445 	print_raid5_conf(conf);
6446 	if (rdev == p->rdev)
6447 		rdevp = &p->rdev;
6448 	else if (rdev == p->replacement)
6449 		rdevp = &p->replacement;
6450 	else
6451 		return 0;
6452 
6453 	if (number >= conf->raid_disks &&
6454 	    conf->reshape_progress == MaxSector)
6455 		clear_bit(In_sync, &rdev->flags);
6456 
6457 	if (test_bit(In_sync, &rdev->flags) ||
6458 	    atomic_read(&rdev->nr_pending)) {
6459 		err = -EBUSY;
6460 		goto abort;
6461 	}
6462 	/* Only remove non-faulty devices if recovery
6463 	 * isn't possible.
6464 	 */
6465 	if (!test_bit(Faulty, &rdev->flags) &&
6466 	    mddev->recovery_disabled != conf->recovery_disabled &&
6467 	    !has_failed(conf) &&
6468 	    (!p->replacement || p->replacement == rdev) &&
6469 	    number < conf->raid_disks) {
6470 		err = -EBUSY;
6471 		goto abort;
6472 	}
6473 	*rdevp = NULL;
6474 	synchronize_rcu();
6475 	if (atomic_read(&rdev->nr_pending)) {
6476 		/* lost the race, try later */
6477 		err = -EBUSY;
6478 		*rdevp = rdev;
6479 	} else if (p->replacement) {
6480 		/* We must have just cleared 'rdev' */
6481 		p->rdev = p->replacement;
6482 		clear_bit(Replacement, &p->replacement->flags);
6483 		smp_mb(); /* Make sure other CPUs may see both as identical
6484 			   * but will never see neither - if they are careful
6485 			   */
6486 		p->replacement = NULL;
6487 		clear_bit(WantReplacement, &rdev->flags);
6488 	} else
6489 		/* We might have just removed the Replacement as faulty-
6490 		 * clear the bit just in case
6491 		 */
6492 		clear_bit(WantReplacement, &rdev->flags);
6493 abort:
6494 
6495 	print_raid5_conf(conf);
6496 	return err;
6497 }
6498 
6499 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
6500 {
6501 	struct r5conf *conf = mddev->private;
6502 	int err = -EEXIST;
6503 	int disk;
6504 	struct disk_info *p;
6505 	int first = 0;
6506 	int last = conf->raid_disks - 1;
6507 
6508 	if (mddev->recovery_disabled == conf->recovery_disabled)
6509 		return -EBUSY;
6510 
6511 	if (rdev->saved_raid_disk < 0 && has_failed(conf))
6512 		/* no point adding a device */
6513 		return -EINVAL;
6514 
6515 	if (rdev->raid_disk >= 0)
6516 		first = last = rdev->raid_disk;
6517 
6518 	/*
6519 	 * find the disk ... but prefer rdev->saved_raid_disk
6520 	 * if possible.
6521 	 */
6522 	if (rdev->saved_raid_disk >= 0 &&
6523 	    rdev->saved_raid_disk >= first &&
6524 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
6525 		first = rdev->saved_raid_disk;
6526 
6527 	for (disk = first; disk <= last; disk++) {
6528 		p = conf->disks + disk;
6529 		if (p->rdev == NULL) {
6530 			clear_bit(In_sync, &rdev->flags);
6531 			rdev->raid_disk = disk;
6532 			err = 0;
6533 			if (rdev->saved_raid_disk != disk)
6534 				conf->fullsync = 1;
6535 			rcu_assign_pointer(p->rdev, rdev);
6536 			goto out;
6537 		}
6538 	}
6539 	for (disk = first; disk <= last; disk++) {
6540 		p = conf->disks + disk;
6541 		if (test_bit(WantReplacement, &p->rdev->flags) &&
6542 		    p->replacement == NULL) {
6543 			clear_bit(In_sync, &rdev->flags);
6544 			set_bit(Replacement, &rdev->flags);
6545 			rdev->raid_disk = disk;
6546 			err = 0;
6547 			conf->fullsync = 1;
6548 			rcu_assign_pointer(p->replacement, rdev);
6549 			break;
6550 		}
6551 	}
6552 out:
6553 	print_raid5_conf(conf);
6554 	return err;
6555 }
6556 
6557 static int raid5_resize(struct mddev *mddev, sector_t sectors)
6558 {
6559 	/* no resync is happening, and there is enough space
6560 	 * on all devices, so we can resize.
6561 	 * We need to make sure resync covers any new space.
6562 	 * If the array is shrinking we should possibly wait until
6563 	 * any io in the removed space completes, but it hardly seems
6564 	 * worth it.
6565 	 */
6566 	sector_t newsize;
6567 	sectors &= ~((sector_t)mddev->chunk_sectors - 1);
6568 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
6569 	if (mddev->external_size &&
6570 	    mddev->array_sectors > newsize)
6571 		return -EINVAL;
6572 	if (mddev->bitmap) {
6573 		int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
6574 		if (ret)
6575 			return ret;
6576 	}
6577 	md_set_array_sectors(mddev, newsize);
6578 	set_capacity(mddev->gendisk, mddev->array_sectors);
6579 	revalidate_disk(mddev->gendisk);
6580 	if (sectors > mddev->dev_sectors &&
6581 	    mddev->recovery_cp > mddev->dev_sectors) {
6582 		mddev->recovery_cp = mddev->dev_sectors;
6583 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
6584 	}
6585 	mddev->dev_sectors = sectors;
6586 	mddev->resync_max_sectors = sectors;
6587 	return 0;
6588 }
6589 
6590 static int check_stripe_cache(struct mddev *mddev)
6591 {
6592 	/* Can only proceed if there are plenty of stripe_heads.
6593 	 * We need a minimum of one full stripe,, and for sensible progress
6594 	 * it is best to have about 4 times that.
6595 	 * If we require 4 times, then the default 256 4K stripe_heads will
6596 	 * allow for chunk sizes up to 256K, which is probably OK.
6597 	 * If the chunk size is greater, user-space should request more
6598 	 * stripe_heads first.
6599 	 */
6600 	struct r5conf *conf = mddev->private;
6601 	if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
6602 	    > conf->max_nr_stripes ||
6603 	    ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
6604 	    > conf->max_nr_stripes) {
6605 		printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
6606 		       mdname(mddev),
6607 		       ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
6608 			/ STRIPE_SIZE)*4);
6609 		return 0;
6610 	}
6611 	return 1;
6612 }
6613 
6614 static int check_reshape(struct mddev *mddev)
6615 {
6616 	struct r5conf *conf = mddev->private;
6617 
6618 	if (mddev->delta_disks == 0 &&
6619 	    mddev->new_layout == mddev->layout &&
6620 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
6621 		return 0; /* nothing to do */
6622 	if (has_failed(conf))
6623 		return -EINVAL;
6624 	if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
6625 		/* We might be able to shrink, but the devices must
6626 		 * be made bigger first.
6627 		 * For raid6, 4 is the minimum size.
6628 		 * Otherwise 2 is the minimum
6629 		 */
6630 		int min = 2;
6631 		if (mddev->level == 6)
6632 			min = 4;
6633 		if (mddev->raid_disks + mddev->delta_disks < min)
6634 			return -EINVAL;
6635 	}
6636 
6637 	if (!check_stripe_cache(mddev))
6638 		return -ENOSPC;
6639 
6640 	return resize_stripes(conf, (conf->previous_raid_disks
6641 				     + mddev->delta_disks));
6642 }
6643 
6644 static int raid5_start_reshape(struct mddev *mddev)
6645 {
6646 	struct r5conf *conf = mddev->private;
6647 	struct md_rdev *rdev;
6648 	int spares = 0;
6649 	unsigned long flags;
6650 
6651 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
6652 		return -EBUSY;
6653 
6654 	if (!check_stripe_cache(mddev))
6655 		return -ENOSPC;
6656 
6657 	if (has_failed(conf))
6658 		return -EINVAL;
6659 
6660 	rdev_for_each(rdev, mddev) {
6661 		if (!test_bit(In_sync, &rdev->flags)
6662 		    && !test_bit(Faulty, &rdev->flags))
6663 			spares++;
6664 	}
6665 
6666 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
6667 		/* Not enough devices even to make a degraded array
6668 		 * of that size
6669 		 */
6670 		return -EINVAL;
6671 
6672 	/* Refuse to reduce size of the array.  Any reductions in
6673 	 * array size must be through explicit setting of array_size
6674 	 * attribute.
6675 	 */
6676 	if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
6677 	    < mddev->array_sectors) {
6678 		printk(KERN_ERR "md/raid:%s: array size must be reduced "
6679 		       "before number of disks\n", mdname(mddev));
6680 		return -EINVAL;
6681 	}
6682 
6683 	atomic_set(&conf->reshape_stripes, 0);
6684 	spin_lock_irq(&conf->device_lock);
6685 	write_seqcount_begin(&conf->gen_lock);
6686 	conf->previous_raid_disks = conf->raid_disks;
6687 	conf->raid_disks += mddev->delta_disks;
6688 	conf->prev_chunk_sectors = conf->chunk_sectors;
6689 	conf->chunk_sectors = mddev->new_chunk_sectors;
6690 	conf->prev_algo = conf->algorithm;
6691 	conf->algorithm = mddev->new_layout;
6692 	conf->generation++;
6693 	/* Code that selects data_offset needs to see the generation update
6694 	 * if reshape_progress has been set - so a memory barrier needed.
6695 	 */
6696 	smp_mb();
6697 	if (mddev->reshape_backwards)
6698 		conf->reshape_progress = raid5_size(mddev, 0, 0);
6699 	else
6700 		conf->reshape_progress = 0;
6701 	conf->reshape_safe = conf->reshape_progress;
6702 	write_seqcount_end(&conf->gen_lock);
6703 	spin_unlock_irq(&conf->device_lock);
6704 
6705 	/* Now make sure any requests that proceeded on the assumption
6706 	 * the reshape wasn't running - like Discard or Read - have
6707 	 * completed.
6708 	 */
6709 	mddev_suspend(mddev);
6710 	mddev_resume(mddev);
6711 
6712 	/* Add some new drives, as many as will fit.
6713 	 * We know there are enough to make the newly sized array work.
6714 	 * Don't add devices if we are reducing the number of
6715 	 * devices in the array.  This is because it is not possible
6716 	 * to correctly record the "partially reconstructed" state of
6717 	 * such devices during the reshape and confusion could result.
6718 	 */
6719 	if (mddev->delta_disks >= 0) {
6720 		rdev_for_each(rdev, mddev)
6721 			if (rdev->raid_disk < 0 &&
6722 			    !test_bit(Faulty, &rdev->flags)) {
6723 				if (raid5_add_disk(mddev, rdev) == 0) {
6724 					if (rdev->raid_disk
6725 					    >= conf->previous_raid_disks)
6726 						set_bit(In_sync, &rdev->flags);
6727 					else
6728 						rdev->recovery_offset = 0;
6729 
6730 					if (sysfs_link_rdev(mddev, rdev))
6731 						/* Failure here is OK */;
6732 				}
6733 			} else if (rdev->raid_disk >= conf->previous_raid_disks
6734 				   && !test_bit(Faulty, &rdev->flags)) {
6735 				/* This is a spare that was manually added */
6736 				set_bit(In_sync, &rdev->flags);
6737 			}
6738 
6739 		/* When a reshape changes the number of devices,
6740 		 * ->degraded is measured against the larger of the
6741 		 * pre and post number of devices.
6742 		 */
6743 		spin_lock_irqsave(&conf->device_lock, flags);
6744 		mddev->degraded = calc_degraded(conf);
6745 		spin_unlock_irqrestore(&conf->device_lock, flags);
6746 	}
6747 	mddev->raid_disks = conf->raid_disks;
6748 	mddev->reshape_position = conf->reshape_progress;
6749 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
6750 
6751 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6752 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6753 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6754 	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6755 	mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6756 						"reshape");
6757 	if (!mddev->sync_thread) {
6758 		mddev->recovery = 0;
6759 		spin_lock_irq(&conf->device_lock);
6760 		write_seqcount_begin(&conf->gen_lock);
6761 		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
6762 		mddev->new_chunk_sectors =
6763 			conf->chunk_sectors = conf->prev_chunk_sectors;
6764 		mddev->new_layout = conf->algorithm = conf->prev_algo;
6765 		rdev_for_each(rdev, mddev)
6766 			rdev->new_data_offset = rdev->data_offset;
6767 		smp_wmb();
6768 		conf->generation --;
6769 		conf->reshape_progress = MaxSector;
6770 		mddev->reshape_position = MaxSector;
6771 		write_seqcount_end(&conf->gen_lock);
6772 		spin_unlock_irq(&conf->device_lock);
6773 		return -EAGAIN;
6774 	}
6775 	conf->reshape_checkpoint = jiffies;
6776 	md_wakeup_thread(mddev->sync_thread);
6777 	md_new_event(mddev);
6778 	return 0;
6779 }
6780 
6781 /* This is called from the reshape thread and should make any
6782  * changes needed in 'conf'
6783  */
6784 static void end_reshape(struct r5conf *conf)
6785 {
6786 
6787 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
6788 		struct md_rdev *rdev;
6789 
6790 		spin_lock_irq(&conf->device_lock);
6791 		conf->previous_raid_disks = conf->raid_disks;
6792 		rdev_for_each(rdev, conf->mddev)
6793 			rdev->data_offset = rdev->new_data_offset;
6794 		smp_wmb();
6795 		conf->reshape_progress = MaxSector;
6796 		spin_unlock_irq(&conf->device_lock);
6797 		wake_up(&conf->wait_for_overlap);
6798 
6799 		/* read-ahead size must cover two whole stripes, which is
6800 		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
6801 		 */
6802 		if (conf->mddev->queue) {
6803 			int data_disks = conf->raid_disks - conf->max_degraded;
6804 			int stripe = data_disks * ((conf->chunk_sectors << 9)
6805 						   / PAGE_SIZE);
6806 			if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6807 				conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6808 		}
6809 	}
6810 }
6811 
6812 /* This is called from the raid5d thread with mddev_lock held.
6813  * It makes config changes to the device.
6814  */
6815 static void raid5_finish_reshape(struct mddev *mddev)
6816 {
6817 	struct r5conf *conf = mddev->private;
6818 
6819 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
6820 
6821 		if (mddev->delta_disks > 0) {
6822 			md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6823 			set_capacity(mddev->gendisk, mddev->array_sectors);
6824 			revalidate_disk(mddev->gendisk);
6825 		} else {
6826 			int d;
6827 			spin_lock_irq(&conf->device_lock);
6828 			mddev->degraded = calc_degraded(conf);
6829 			spin_unlock_irq(&conf->device_lock);
6830 			for (d = conf->raid_disks ;
6831 			     d < conf->raid_disks - mddev->delta_disks;
6832 			     d++) {
6833 				struct md_rdev *rdev = conf->disks[d].rdev;
6834 				if (rdev)
6835 					clear_bit(In_sync, &rdev->flags);
6836 				rdev = conf->disks[d].replacement;
6837 				if (rdev)
6838 					clear_bit(In_sync, &rdev->flags);
6839 			}
6840 		}
6841 		mddev->layout = conf->algorithm;
6842 		mddev->chunk_sectors = conf->chunk_sectors;
6843 		mddev->reshape_position = MaxSector;
6844 		mddev->delta_disks = 0;
6845 		mddev->reshape_backwards = 0;
6846 	}
6847 }
6848 
6849 static void raid5_quiesce(struct mddev *mddev, int state)
6850 {
6851 	struct r5conf *conf = mddev->private;
6852 
6853 	switch(state) {
6854 	case 2: /* resume for a suspend */
6855 		wake_up(&conf->wait_for_overlap);
6856 		break;
6857 
6858 	case 1: /* stop all writes */
6859 		lock_all_device_hash_locks_irq(conf);
6860 		/* '2' tells resync/reshape to pause so that all
6861 		 * active stripes can drain
6862 		 */
6863 		conf->quiesce = 2;
6864 		wait_event_cmd(conf->wait_for_stripe,
6865 				    atomic_read(&conf->active_stripes) == 0 &&
6866 				    atomic_read(&conf->active_aligned_reads) == 0,
6867 				    unlock_all_device_hash_locks_irq(conf),
6868 				    lock_all_device_hash_locks_irq(conf));
6869 		conf->quiesce = 1;
6870 		unlock_all_device_hash_locks_irq(conf);
6871 		/* allow reshape to continue */
6872 		wake_up(&conf->wait_for_overlap);
6873 		break;
6874 
6875 	case 0: /* re-enable writes */
6876 		lock_all_device_hash_locks_irq(conf);
6877 		conf->quiesce = 0;
6878 		wake_up(&conf->wait_for_stripe);
6879 		wake_up(&conf->wait_for_overlap);
6880 		unlock_all_device_hash_locks_irq(conf);
6881 		break;
6882 	}
6883 }
6884 
6885 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
6886 {
6887 	struct r0conf *raid0_conf = mddev->private;
6888 	sector_t sectors;
6889 
6890 	/* for raid0 takeover only one zone is supported */
6891 	if (raid0_conf->nr_strip_zones > 1) {
6892 		printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
6893 		       mdname(mddev));
6894 		return ERR_PTR(-EINVAL);
6895 	}
6896 
6897 	sectors = raid0_conf->strip_zone[0].zone_end;
6898 	sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
6899 	mddev->dev_sectors = sectors;
6900 	mddev->new_level = level;
6901 	mddev->new_layout = ALGORITHM_PARITY_N;
6902 	mddev->new_chunk_sectors = mddev->chunk_sectors;
6903 	mddev->raid_disks += 1;
6904 	mddev->delta_disks = 1;
6905 	/* make sure it will be not marked as dirty */
6906 	mddev->recovery_cp = MaxSector;
6907 
6908 	return setup_conf(mddev);
6909 }
6910 
6911 static void *raid5_takeover_raid1(struct mddev *mddev)
6912 {
6913 	int chunksect;
6914 
6915 	if (mddev->raid_disks != 2 ||
6916 	    mddev->degraded > 1)
6917 		return ERR_PTR(-EINVAL);
6918 
6919 	/* Should check if there are write-behind devices? */
6920 
6921 	chunksect = 64*2; /* 64K by default */
6922 
6923 	/* The array must be an exact multiple of chunksize */
6924 	while (chunksect && (mddev->array_sectors & (chunksect-1)))
6925 		chunksect >>= 1;
6926 
6927 	if ((chunksect<<9) < STRIPE_SIZE)
6928 		/* array size does not allow a suitable chunk size */
6929 		return ERR_PTR(-EINVAL);
6930 
6931 	mddev->new_level = 5;
6932 	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
6933 	mddev->new_chunk_sectors = chunksect;
6934 
6935 	return setup_conf(mddev);
6936 }
6937 
6938 static void *raid5_takeover_raid6(struct mddev *mddev)
6939 {
6940 	int new_layout;
6941 
6942 	switch (mddev->layout) {
6943 	case ALGORITHM_LEFT_ASYMMETRIC_6:
6944 		new_layout = ALGORITHM_LEFT_ASYMMETRIC;
6945 		break;
6946 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
6947 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
6948 		break;
6949 	case ALGORITHM_LEFT_SYMMETRIC_6:
6950 		new_layout = ALGORITHM_LEFT_SYMMETRIC;
6951 		break;
6952 	case ALGORITHM_RIGHT_SYMMETRIC_6:
6953 		new_layout = ALGORITHM_RIGHT_SYMMETRIC;
6954 		break;
6955 	case ALGORITHM_PARITY_0_6:
6956 		new_layout = ALGORITHM_PARITY_0;
6957 		break;
6958 	case ALGORITHM_PARITY_N:
6959 		new_layout = ALGORITHM_PARITY_N;
6960 		break;
6961 	default:
6962 		return ERR_PTR(-EINVAL);
6963 	}
6964 	mddev->new_level = 5;
6965 	mddev->new_layout = new_layout;
6966 	mddev->delta_disks = -1;
6967 	mddev->raid_disks -= 1;
6968 	return setup_conf(mddev);
6969 }
6970 
6971 static int raid5_check_reshape(struct mddev *mddev)
6972 {
6973 	/* For a 2-drive array, the layout and chunk size can be changed
6974 	 * immediately as not restriping is needed.
6975 	 * For larger arrays we record the new value - after validation
6976 	 * to be used by a reshape pass.
6977 	 */
6978 	struct r5conf *conf = mddev->private;
6979 	int new_chunk = mddev->new_chunk_sectors;
6980 
6981 	if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
6982 		return -EINVAL;
6983 	if (new_chunk > 0) {
6984 		if (!is_power_of_2(new_chunk))
6985 			return -EINVAL;
6986 		if (new_chunk < (PAGE_SIZE>>9))
6987 			return -EINVAL;
6988 		if (mddev->array_sectors & (new_chunk-1))
6989 			/* not factor of array size */
6990 			return -EINVAL;
6991 	}
6992 
6993 	/* They look valid */
6994 
6995 	if (mddev->raid_disks == 2) {
6996 		/* can make the change immediately */
6997 		if (mddev->new_layout >= 0) {
6998 			conf->algorithm = mddev->new_layout;
6999 			mddev->layout = mddev->new_layout;
7000 		}
7001 		if (new_chunk > 0) {
7002 			conf->chunk_sectors = new_chunk ;
7003 			mddev->chunk_sectors = new_chunk;
7004 		}
7005 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
7006 		md_wakeup_thread(mddev->thread);
7007 	}
7008 	return check_reshape(mddev);
7009 }
7010 
7011 static int raid6_check_reshape(struct mddev *mddev)
7012 {
7013 	int new_chunk = mddev->new_chunk_sectors;
7014 
7015 	if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
7016 		return -EINVAL;
7017 	if (new_chunk > 0) {
7018 		if (!is_power_of_2(new_chunk))
7019 			return -EINVAL;
7020 		if (new_chunk < (PAGE_SIZE >> 9))
7021 			return -EINVAL;
7022 		if (mddev->array_sectors & (new_chunk-1))
7023 			/* not factor of array size */
7024 			return -EINVAL;
7025 	}
7026 
7027 	/* They look valid */
7028 	return check_reshape(mddev);
7029 }
7030 
7031 static void *raid5_takeover(struct mddev *mddev)
7032 {
7033 	/* raid5 can take over:
7034 	 *  raid0 - if there is only one strip zone - make it a raid4 layout
7035 	 *  raid1 - if there are two drives.  We need to know the chunk size
7036 	 *  raid4 - trivial - just use a raid4 layout.
7037 	 *  raid6 - Providing it is a *_6 layout
7038 	 */
7039 	if (mddev->level == 0)
7040 		return raid45_takeover_raid0(mddev, 5);
7041 	if (mddev->level == 1)
7042 		return raid5_takeover_raid1(mddev);
7043 	if (mddev->level == 4) {
7044 		mddev->new_layout = ALGORITHM_PARITY_N;
7045 		mddev->new_level = 5;
7046 		return setup_conf(mddev);
7047 	}
7048 	if (mddev->level == 6)
7049 		return raid5_takeover_raid6(mddev);
7050 
7051 	return ERR_PTR(-EINVAL);
7052 }
7053 
7054 static void *raid4_takeover(struct mddev *mddev)
7055 {
7056 	/* raid4 can take over:
7057 	 *  raid0 - if there is only one strip zone
7058 	 *  raid5 - if layout is right
7059 	 */
7060 	if (mddev->level == 0)
7061 		return raid45_takeover_raid0(mddev, 4);
7062 	if (mddev->level == 5 &&
7063 	    mddev->layout == ALGORITHM_PARITY_N) {
7064 		mddev->new_layout = 0;
7065 		mddev->new_level = 4;
7066 		return setup_conf(mddev);
7067 	}
7068 	return ERR_PTR(-EINVAL);
7069 }
7070 
7071 static struct md_personality raid5_personality;
7072 
7073 static void *raid6_takeover(struct mddev *mddev)
7074 {
7075 	/* Currently can only take over a raid5.  We map the
7076 	 * personality to an equivalent raid6 personality
7077 	 * with the Q block at the end.
7078 	 */
7079 	int new_layout;
7080 
7081 	if (mddev->pers != &raid5_personality)
7082 		return ERR_PTR(-EINVAL);
7083 	if (mddev->degraded > 1)
7084 		return ERR_PTR(-EINVAL);
7085 	if (mddev->raid_disks > 253)
7086 		return ERR_PTR(-EINVAL);
7087 	if (mddev->raid_disks < 3)
7088 		return ERR_PTR(-EINVAL);
7089 
7090 	switch (mddev->layout) {
7091 	case ALGORITHM_LEFT_ASYMMETRIC:
7092 		new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
7093 		break;
7094 	case ALGORITHM_RIGHT_ASYMMETRIC:
7095 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
7096 		break;
7097 	case ALGORITHM_LEFT_SYMMETRIC:
7098 		new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
7099 		break;
7100 	case ALGORITHM_RIGHT_SYMMETRIC:
7101 		new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
7102 		break;
7103 	case ALGORITHM_PARITY_0:
7104 		new_layout = ALGORITHM_PARITY_0_6;
7105 		break;
7106 	case ALGORITHM_PARITY_N:
7107 		new_layout = ALGORITHM_PARITY_N;
7108 		break;
7109 	default:
7110 		return ERR_PTR(-EINVAL);
7111 	}
7112 	mddev->new_level = 6;
7113 	mddev->new_layout = new_layout;
7114 	mddev->delta_disks = 1;
7115 	mddev->raid_disks += 1;
7116 	return setup_conf(mddev);
7117 }
7118 
7119 static struct md_personality raid6_personality =
7120 {
7121 	.name		= "raid6",
7122 	.level		= 6,
7123 	.owner		= THIS_MODULE,
7124 	.make_request	= make_request,
7125 	.run		= run,
7126 	.free		= raid5_free,
7127 	.status		= status,
7128 	.error_handler	= error,
7129 	.hot_add_disk	= raid5_add_disk,
7130 	.hot_remove_disk= raid5_remove_disk,
7131 	.spare_active	= raid5_spare_active,
7132 	.sync_request	= sync_request,
7133 	.resize		= raid5_resize,
7134 	.size		= raid5_size,
7135 	.check_reshape	= raid6_check_reshape,
7136 	.start_reshape  = raid5_start_reshape,
7137 	.finish_reshape = raid5_finish_reshape,
7138 	.quiesce	= raid5_quiesce,
7139 	.takeover	= raid6_takeover,
7140 	.congested	= raid5_congested,
7141 	.mergeable_bvec	= raid5_mergeable_bvec,
7142 };
7143 static struct md_personality raid5_personality =
7144 {
7145 	.name		= "raid5",
7146 	.level		= 5,
7147 	.owner		= THIS_MODULE,
7148 	.make_request	= make_request,
7149 	.run		= run,
7150 	.free		= raid5_free,
7151 	.status		= status,
7152 	.error_handler	= error,
7153 	.hot_add_disk	= raid5_add_disk,
7154 	.hot_remove_disk= raid5_remove_disk,
7155 	.spare_active	= raid5_spare_active,
7156 	.sync_request	= sync_request,
7157 	.resize		= raid5_resize,
7158 	.size		= raid5_size,
7159 	.check_reshape	= raid5_check_reshape,
7160 	.start_reshape  = raid5_start_reshape,
7161 	.finish_reshape = raid5_finish_reshape,
7162 	.quiesce	= raid5_quiesce,
7163 	.takeover	= raid5_takeover,
7164 	.congested	= raid5_congested,
7165 	.mergeable_bvec	= raid5_mergeable_bvec,
7166 };
7167 
7168 static struct md_personality raid4_personality =
7169 {
7170 	.name		= "raid4",
7171 	.level		= 4,
7172 	.owner		= THIS_MODULE,
7173 	.make_request	= make_request,
7174 	.run		= run,
7175 	.free		= raid5_free,
7176 	.status		= status,
7177 	.error_handler	= error,
7178 	.hot_add_disk	= raid5_add_disk,
7179 	.hot_remove_disk= raid5_remove_disk,
7180 	.spare_active	= raid5_spare_active,
7181 	.sync_request	= sync_request,
7182 	.resize		= raid5_resize,
7183 	.size		= raid5_size,
7184 	.check_reshape	= raid5_check_reshape,
7185 	.start_reshape  = raid5_start_reshape,
7186 	.finish_reshape = raid5_finish_reshape,
7187 	.quiesce	= raid5_quiesce,
7188 	.takeover	= raid4_takeover,
7189 	.congested	= raid5_congested,
7190 	.mergeable_bvec	= raid5_mergeable_bvec,
7191 };
7192 
7193 static int __init raid5_init(void)
7194 {
7195 	raid5_wq = alloc_workqueue("raid5wq",
7196 		WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
7197 	if (!raid5_wq)
7198 		return -ENOMEM;
7199 	register_md_personality(&raid6_personality);
7200 	register_md_personality(&raid5_personality);
7201 	register_md_personality(&raid4_personality);
7202 	return 0;
7203 }
7204 
7205 static void raid5_exit(void)
7206 {
7207 	unregister_md_personality(&raid6_personality);
7208 	unregister_md_personality(&raid5_personality);
7209 	unregister_md_personality(&raid4_personality);
7210 	destroy_workqueue(raid5_wq);
7211 }
7212 
7213 module_init(raid5_init);
7214 module_exit(raid5_exit);
7215 MODULE_LICENSE("GPL");
7216 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
7217 MODULE_ALIAS("md-personality-4"); /* RAID5 */
7218 MODULE_ALIAS("md-raid5");
7219 MODULE_ALIAS("md-raid4");
7220 MODULE_ALIAS("md-level-5");
7221 MODULE_ALIAS("md-level-4");
7222 MODULE_ALIAS("md-personality-8"); /* RAID6 */
7223 MODULE_ALIAS("md-raid6");
7224 MODULE_ALIAS("md-level-6");
7225 
7226 /* This used to be two separate modules, they were: */
7227 MODULE_ALIAS("raid5");
7228 MODULE_ALIAS("raid6");
7229