xref: /openbmc/linux/drivers/md/raid5.c (revision ae3473231e77a3f1909d48cd144cebe5e1d049b3)
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 <linux/flex_array.h>
58 #include <trace/events/block.h>
59 
60 #include "md.h"
61 #include "raid5.h"
62 #include "raid0.h"
63 #include "bitmap.h"
64 
65 #define cpu_to_group(cpu) cpu_to_node(cpu)
66 #define ANY_GROUP NUMA_NO_NODE
67 
68 static bool devices_handle_discard_safely = false;
69 module_param(devices_handle_discard_safely, bool, 0644);
70 MODULE_PARM_DESC(devices_handle_discard_safely,
71 		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
72 static struct workqueue_struct *raid5_wq;
73 
74 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
75 {
76 	int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
77 	return &conf->stripe_hashtbl[hash];
78 }
79 
80 static inline int stripe_hash_locks_hash(sector_t sect)
81 {
82 	return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
83 }
84 
85 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
86 {
87 	spin_lock_irq(conf->hash_locks + hash);
88 	spin_lock(&conf->device_lock);
89 }
90 
91 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
92 {
93 	spin_unlock(&conf->device_lock);
94 	spin_unlock_irq(conf->hash_locks + hash);
95 }
96 
97 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
98 {
99 	int i;
100 	local_irq_disable();
101 	spin_lock(conf->hash_locks);
102 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
103 		spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
104 	spin_lock(&conf->device_lock);
105 }
106 
107 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
108 {
109 	int i;
110 	spin_unlock(&conf->device_lock);
111 	for (i = NR_STRIPE_HASH_LOCKS; i; i--)
112 		spin_unlock(conf->hash_locks + i - 1);
113 	local_irq_enable();
114 }
115 
116 /* Find first data disk in a raid6 stripe */
117 static inline int raid6_d0(struct stripe_head *sh)
118 {
119 	if (sh->ddf_layout)
120 		/* ddf always start from first device */
121 		return 0;
122 	/* md starts just after Q block */
123 	if (sh->qd_idx == sh->disks - 1)
124 		return 0;
125 	else
126 		return sh->qd_idx + 1;
127 }
128 static inline int raid6_next_disk(int disk, int raid_disks)
129 {
130 	disk++;
131 	return (disk < raid_disks) ? disk : 0;
132 }
133 
134 /* When walking through the disks in a raid5, starting at raid6_d0,
135  * We need to map each disk to a 'slot', where the data disks are slot
136  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
137  * is raid_disks-1.  This help does that mapping.
138  */
139 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
140 			     int *count, int syndrome_disks)
141 {
142 	int slot = *count;
143 
144 	if (sh->ddf_layout)
145 		(*count)++;
146 	if (idx == sh->pd_idx)
147 		return syndrome_disks;
148 	if (idx == sh->qd_idx)
149 		return syndrome_disks + 1;
150 	if (!sh->ddf_layout)
151 		(*count)++;
152 	return slot;
153 }
154 
155 static void return_io(struct bio_list *return_bi)
156 {
157 	struct bio *bi;
158 	while ((bi = bio_list_pop(return_bi)) != NULL) {
159 		bi->bi_iter.bi_size = 0;
160 		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
161 					 bi, 0);
162 		bio_endio(bi);
163 	}
164 }
165 
166 static void print_raid5_conf (struct r5conf *conf);
167 
168 static int stripe_operations_active(struct stripe_head *sh)
169 {
170 	return sh->check_state || sh->reconstruct_state ||
171 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
172 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
173 }
174 
175 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
176 {
177 	struct r5conf *conf = sh->raid_conf;
178 	struct r5worker_group *group;
179 	int thread_cnt;
180 	int i, cpu = sh->cpu;
181 
182 	if (!cpu_online(cpu)) {
183 		cpu = cpumask_any(cpu_online_mask);
184 		sh->cpu = cpu;
185 	}
186 
187 	if (list_empty(&sh->lru)) {
188 		struct r5worker_group *group;
189 		group = conf->worker_groups + cpu_to_group(cpu);
190 		list_add_tail(&sh->lru, &group->handle_list);
191 		group->stripes_cnt++;
192 		sh->group = group;
193 	}
194 
195 	if (conf->worker_cnt_per_group == 0) {
196 		md_wakeup_thread(conf->mddev->thread);
197 		return;
198 	}
199 
200 	group = conf->worker_groups + cpu_to_group(sh->cpu);
201 
202 	group->workers[0].working = true;
203 	/* at least one worker should run to avoid race */
204 	queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
205 
206 	thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
207 	/* wakeup more workers */
208 	for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
209 		if (group->workers[i].working == false) {
210 			group->workers[i].working = true;
211 			queue_work_on(sh->cpu, raid5_wq,
212 				      &group->workers[i].work);
213 			thread_cnt--;
214 		}
215 	}
216 }
217 
218 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
219 			      struct list_head *temp_inactive_list)
220 {
221 	int i;
222 	int injournal = 0;	/* number of date pages with R5_InJournal */
223 
224 	BUG_ON(!list_empty(&sh->lru));
225 	BUG_ON(atomic_read(&conf->active_stripes)==0);
226 
227 	if (r5c_is_writeback(conf->log))
228 		for (i = sh->disks; i--; )
229 			if (test_bit(R5_InJournal, &sh->dev[i].flags))
230 				injournal++;
231 	/*
232 	 * When quiesce in r5c write back, set STRIPE_HANDLE for stripes with
233 	 * data in journal, so they are not released to cached lists
234 	 */
235 	if (conf->quiesce && r5c_is_writeback(conf->log) &&
236 	    !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0) {
237 		if (test_bit(STRIPE_R5C_CACHING, &sh->state))
238 			r5c_make_stripe_write_out(sh);
239 		set_bit(STRIPE_HANDLE, &sh->state);
240 	}
241 
242 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
243 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
244 		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
245 			list_add_tail(&sh->lru, &conf->delayed_list);
246 		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
247 			   sh->bm_seq - conf->seq_write > 0)
248 			list_add_tail(&sh->lru, &conf->bitmap_list);
249 		else {
250 			clear_bit(STRIPE_DELAYED, &sh->state);
251 			clear_bit(STRIPE_BIT_DELAY, &sh->state);
252 			if (conf->worker_cnt_per_group == 0) {
253 				list_add_tail(&sh->lru, &conf->handle_list);
254 			} else {
255 				raid5_wakeup_stripe_thread(sh);
256 				return;
257 			}
258 		}
259 		md_wakeup_thread(conf->mddev->thread);
260 	} else {
261 		BUG_ON(stripe_operations_active(sh));
262 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
263 			if (atomic_dec_return(&conf->preread_active_stripes)
264 			    < IO_THRESHOLD)
265 				md_wakeup_thread(conf->mddev->thread);
266 		atomic_dec(&conf->active_stripes);
267 		if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
268 			if (!r5c_is_writeback(conf->log))
269 				list_add_tail(&sh->lru, temp_inactive_list);
270 			else {
271 				WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
272 				if (injournal == 0)
273 					list_add_tail(&sh->lru, temp_inactive_list);
274 				else if (injournal == conf->raid_disks - conf->max_degraded) {
275 					/* full stripe */
276 					if (!test_and_set_bit(STRIPE_R5C_FULL_STRIPE, &sh->state))
277 						atomic_inc(&conf->r5c_cached_full_stripes);
278 					if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
279 						atomic_dec(&conf->r5c_cached_partial_stripes);
280 					list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
281 					r5c_check_cached_full_stripe(conf);
282 				} else {
283 					/* partial stripe */
284 					if (!test_and_set_bit(STRIPE_R5C_PARTIAL_STRIPE,
285 							      &sh->state))
286 						atomic_inc(&conf->r5c_cached_partial_stripes);
287 					list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
288 				}
289 			}
290 		}
291 	}
292 }
293 
294 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
295 			     struct list_head *temp_inactive_list)
296 {
297 	if (atomic_dec_and_test(&sh->count))
298 		do_release_stripe(conf, sh, temp_inactive_list);
299 }
300 
301 /*
302  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
303  *
304  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
305  * given time. Adding stripes only takes device lock, while deleting stripes
306  * only takes hash lock.
307  */
308 static void release_inactive_stripe_list(struct r5conf *conf,
309 					 struct list_head *temp_inactive_list,
310 					 int hash)
311 {
312 	int size;
313 	bool do_wakeup = false;
314 	unsigned long flags;
315 
316 	if (hash == NR_STRIPE_HASH_LOCKS) {
317 		size = NR_STRIPE_HASH_LOCKS;
318 		hash = NR_STRIPE_HASH_LOCKS - 1;
319 	} else
320 		size = 1;
321 	while (size) {
322 		struct list_head *list = &temp_inactive_list[size - 1];
323 
324 		/*
325 		 * We don't hold any lock here yet, raid5_get_active_stripe() might
326 		 * remove stripes from the list
327 		 */
328 		if (!list_empty_careful(list)) {
329 			spin_lock_irqsave(conf->hash_locks + hash, flags);
330 			if (list_empty(conf->inactive_list + hash) &&
331 			    !list_empty(list))
332 				atomic_dec(&conf->empty_inactive_list_nr);
333 			list_splice_tail_init(list, conf->inactive_list + hash);
334 			do_wakeup = true;
335 			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
336 		}
337 		size--;
338 		hash--;
339 	}
340 
341 	if (do_wakeup) {
342 		wake_up(&conf->wait_for_stripe);
343 		if (atomic_read(&conf->active_stripes) == 0)
344 			wake_up(&conf->wait_for_quiescent);
345 		if (conf->retry_read_aligned)
346 			md_wakeup_thread(conf->mddev->thread);
347 	}
348 }
349 
350 /* should hold conf->device_lock already */
351 static int release_stripe_list(struct r5conf *conf,
352 			       struct list_head *temp_inactive_list)
353 {
354 	struct stripe_head *sh;
355 	int count = 0;
356 	struct llist_node *head;
357 
358 	head = llist_del_all(&conf->released_stripes);
359 	head = llist_reverse_order(head);
360 	while (head) {
361 		int hash;
362 
363 		sh = llist_entry(head, struct stripe_head, release_list);
364 		head = llist_next(head);
365 		/* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
366 		smp_mb();
367 		clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
368 		/*
369 		 * Don't worry the bit is set here, because if the bit is set
370 		 * again, the count is always > 1. This is true for
371 		 * STRIPE_ON_UNPLUG_LIST bit too.
372 		 */
373 		hash = sh->hash_lock_index;
374 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
375 		count++;
376 	}
377 
378 	return count;
379 }
380 
381 void raid5_release_stripe(struct stripe_head *sh)
382 {
383 	struct r5conf *conf = sh->raid_conf;
384 	unsigned long flags;
385 	struct list_head list;
386 	int hash;
387 	bool wakeup;
388 
389 	/* Avoid release_list until the last reference.
390 	 */
391 	if (atomic_add_unless(&sh->count, -1, 1))
392 		return;
393 
394 	if (unlikely(!conf->mddev->thread) ||
395 		test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
396 		goto slow_path;
397 	wakeup = llist_add(&sh->release_list, &conf->released_stripes);
398 	if (wakeup)
399 		md_wakeup_thread(conf->mddev->thread);
400 	return;
401 slow_path:
402 	local_irq_save(flags);
403 	/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
404 	if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
405 		INIT_LIST_HEAD(&list);
406 		hash = sh->hash_lock_index;
407 		do_release_stripe(conf, sh, &list);
408 		spin_unlock(&conf->device_lock);
409 		release_inactive_stripe_list(conf, &list, hash);
410 	}
411 	local_irq_restore(flags);
412 }
413 
414 static inline void remove_hash(struct stripe_head *sh)
415 {
416 	pr_debug("remove_hash(), stripe %llu\n",
417 		(unsigned long long)sh->sector);
418 
419 	hlist_del_init(&sh->hash);
420 }
421 
422 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
423 {
424 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
425 
426 	pr_debug("insert_hash(), stripe %llu\n",
427 		(unsigned long long)sh->sector);
428 
429 	hlist_add_head(&sh->hash, hp);
430 }
431 
432 /* find an idle stripe, make sure it is unhashed, and return it. */
433 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
434 {
435 	struct stripe_head *sh = NULL;
436 	struct list_head *first;
437 
438 	if (list_empty(conf->inactive_list + hash))
439 		goto out;
440 	first = (conf->inactive_list + hash)->next;
441 	sh = list_entry(first, struct stripe_head, lru);
442 	list_del_init(first);
443 	remove_hash(sh);
444 	atomic_inc(&conf->active_stripes);
445 	BUG_ON(hash != sh->hash_lock_index);
446 	if (list_empty(conf->inactive_list + hash))
447 		atomic_inc(&conf->empty_inactive_list_nr);
448 out:
449 	return sh;
450 }
451 
452 static void shrink_buffers(struct stripe_head *sh)
453 {
454 	struct page *p;
455 	int i;
456 	int num = sh->raid_conf->pool_size;
457 
458 	for (i = 0; i < num ; i++) {
459 		WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
460 		p = sh->dev[i].page;
461 		if (!p)
462 			continue;
463 		sh->dev[i].page = NULL;
464 		put_page(p);
465 	}
466 }
467 
468 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
469 {
470 	int i;
471 	int num = sh->raid_conf->pool_size;
472 
473 	for (i = 0; i < num; i++) {
474 		struct page *page;
475 
476 		if (!(page = alloc_page(gfp))) {
477 			return 1;
478 		}
479 		sh->dev[i].page = page;
480 		sh->dev[i].orig_page = page;
481 	}
482 	return 0;
483 }
484 
485 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
486 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
487 			    struct stripe_head *sh);
488 
489 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
490 {
491 	struct r5conf *conf = sh->raid_conf;
492 	int i, seq;
493 
494 	BUG_ON(atomic_read(&sh->count) != 0);
495 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
496 	BUG_ON(stripe_operations_active(sh));
497 	BUG_ON(sh->batch_head);
498 
499 	pr_debug("init_stripe called, stripe %llu\n",
500 		(unsigned long long)sector);
501 retry:
502 	seq = read_seqcount_begin(&conf->gen_lock);
503 	sh->generation = conf->generation - previous;
504 	sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
505 	sh->sector = sector;
506 	stripe_set_idx(sector, conf, previous, sh);
507 	sh->state = 0;
508 
509 	for (i = sh->disks; i--; ) {
510 		struct r5dev *dev = &sh->dev[i];
511 
512 		if (dev->toread || dev->read || dev->towrite || dev->written ||
513 		    test_bit(R5_LOCKED, &dev->flags)) {
514 			pr_err("sector=%llx i=%d %p %p %p %p %d\n",
515 			       (unsigned long long)sh->sector, i, dev->toread,
516 			       dev->read, dev->towrite, dev->written,
517 			       test_bit(R5_LOCKED, &dev->flags));
518 			WARN_ON(1);
519 		}
520 		dev->flags = 0;
521 		raid5_build_block(sh, i, previous);
522 	}
523 	if (read_seqcount_retry(&conf->gen_lock, seq))
524 		goto retry;
525 	sh->overwrite_disks = 0;
526 	insert_hash(conf, sh);
527 	sh->cpu = smp_processor_id();
528 	set_bit(STRIPE_BATCH_READY, &sh->state);
529 }
530 
531 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
532 					 short generation)
533 {
534 	struct stripe_head *sh;
535 
536 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
537 	hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
538 		if (sh->sector == sector && sh->generation == generation)
539 			return sh;
540 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
541 	return NULL;
542 }
543 
544 /*
545  * Need to check if array has failed when deciding whether to:
546  *  - start an array
547  *  - remove non-faulty devices
548  *  - add a spare
549  *  - allow a reshape
550  * This determination is simple when no reshape is happening.
551  * However if there is a reshape, we need to carefully check
552  * both the before and after sections.
553  * This is because some failed devices may only affect one
554  * of the two sections, and some non-in_sync devices may
555  * be insync in the section most affected by failed devices.
556  */
557 static int calc_degraded(struct r5conf *conf)
558 {
559 	int degraded, degraded2;
560 	int i;
561 
562 	rcu_read_lock();
563 	degraded = 0;
564 	for (i = 0; i < conf->previous_raid_disks; i++) {
565 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
566 		if (rdev && test_bit(Faulty, &rdev->flags))
567 			rdev = rcu_dereference(conf->disks[i].replacement);
568 		if (!rdev || test_bit(Faulty, &rdev->flags))
569 			degraded++;
570 		else if (test_bit(In_sync, &rdev->flags))
571 			;
572 		else
573 			/* not in-sync or faulty.
574 			 * If the reshape increases the number of devices,
575 			 * this is being recovered by the reshape, so
576 			 * this 'previous' section is not in_sync.
577 			 * If the number of devices is being reduced however,
578 			 * the device can only be part of the array if
579 			 * we are reverting a reshape, so this section will
580 			 * be in-sync.
581 			 */
582 			if (conf->raid_disks >= conf->previous_raid_disks)
583 				degraded++;
584 	}
585 	rcu_read_unlock();
586 	if (conf->raid_disks == conf->previous_raid_disks)
587 		return degraded;
588 	rcu_read_lock();
589 	degraded2 = 0;
590 	for (i = 0; i < conf->raid_disks; i++) {
591 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
592 		if (rdev && test_bit(Faulty, &rdev->flags))
593 			rdev = rcu_dereference(conf->disks[i].replacement);
594 		if (!rdev || test_bit(Faulty, &rdev->flags))
595 			degraded2++;
596 		else if (test_bit(In_sync, &rdev->flags))
597 			;
598 		else
599 			/* not in-sync or faulty.
600 			 * If reshape increases the number of devices, this
601 			 * section has already been recovered, else it
602 			 * almost certainly hasn't.
603 			 */
604 			if (conf->raid_disks <= conf->previous_raid_disks)
605 				degraded2++;
606 	}
607 	rcu_read_unlock();
608 	if (degraded2 > degraded)
609 		return degraded2;
610 	return degraded;
611 }
612 
613 static int has_failed(struct r5conf *conf)
614 {
615 	int degraded;
616 
617 	if (conf->mddev->reshape_position == MaxSector)
618 		return conf->mddev->degraded > conf->max_degraded;
619 
620 	degraded = calc_degraded(conf);
621 	if (degraded > conf->max_degraded)
622 		return 1;
623 	return 0;
624 }
625 
626 struct stripe_head *
627 raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
628 			int previous, int noblock, int noquiesce)
629 {
630 	struct stripe_head *sh;
631 	int hash = stripe_hash_locks_hash(sector);
632 	int inc_empty_inactive_list_flag;
633 
634 	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
635 
636 	spin_lock_irq(conf->hash_locks + hash);
637 
638 	do {
639 		wait_event_lock_irq(conf->wait_for_quiescent,
640 				    conf->quiesce == 0 || noquiesce,
641 				    *(conf->hash_locks + hash));
642 		sh = __find_stripe(conf, sector, conf->generation - previous);
643 		if (!sh) {
644 			if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
645 				sh = get_free_stripe(conf, hash);
646 				if (!sh && !test_bit(R5_DID_ALLOC,
647 						     &conf->cache_state))
648 					set_bit(R5_ALLOC_MORE,
649 						&conf->cache_state);
650 			}
651 			if (noblock && sh == NULL)
652 				break;
653 
654 			r5c_check_stripe_cache_usage(conf);
655 			if (!sh) {
656 				set_bit(R5_INACTIVE_BLOCKED,
657 					&conf->cache_state);
658 				r5l_wake_reclaim(conf->log, 0);
659 				wait_event_lock_irq(
660 					conf->wait_for_stripe,
661 					!list_empty(conf->inactive_list + hash) &&
662 					(atomic_read(&conf->active_stripes)
663 					 < (conf->max_nr_stripes * 3 / 4)
664 					 || !test_bit(R5_INACTIVE_BLOCKED,
665 						      &conf->cache_state)),
666 					*(conf->hash_locks + hash));
667 				clear_bit(R5_INACTIVE_BLOCKED,
668 					  &conf->cache_state);
669 			} else {
670 				init_stripe(sh, sector, previous);
671 				atomic_inc(&sh->count);
672 			}
673 		} else if (!atomic_inc_not_zero(&sh->count)) {
674 			spin_lock(&conf->device_lock);
675 			if (!atomic_read(&sh->count)) {
676 				if (!test_bit(STRIPE_HANDLE, &sh->state))
677 					atomic_inc(&conf->active_stripes);
678 				BUG_ON(list_empty(&sh->lru) &&
679 				       !test_bit(STRIPE_EXPANDING, &sh->state));
680 				inc_empty_inactive_list_flag = 0;
681 				if (!list_empty(conf->inactive_list + hash))
682 					inc_empty_inactive_list_flag = 1;
683 				list_del_init(&sh->lru);
684 				if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
685 					atomic_inc(&conf->empty_inactive_list_nr);
686 				if (sh->group) {
687 					sh->group->stripes_cnt--;
688 					sh->group = NULL;
689 				}
690 			}
691 			atomic_inc(&sh->count);
692 			spin_unlock(&conf->device_lock);
693 		}
694 	} while (sh == NULL);
695 
696 	spin_unlock_irq(conf->hash_locks + hash);
697 	return sh;
698 }
699 
700 static bool is_full_stripe_write(struct stripe_head *sh)
701 {
702 	BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
703 	return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
704 }
705 
706 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
707 {
708 	local_irq_disable();
709 	if (sh1 > sh2) {
710 		spin_lock(&sh2->stripe_lock);
711 		spin_lock_nested(&sh1->stripe_lock, 1);
712 	} else {
713 		spin_lock(&sh1->stripe_lock);
714 		spin_lock_nested(&sh2->stripe_lock, 1);
715 	}
716 }
717 
718 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
719 {
720 	spin_unlock(&sh1->stripe_lock);
721 	spin_unlock(&sh2->stripe_lock);
722 	local_irq_enable();
723 }
724 
725 /* Only freshly new full stripe normal write stripe can be added to a batch list */
726 static bool stripe_can_batch(struct stripe_head *sh)
727 {
728 	struct r5conf *conf = sh->raid_conf;
729 
730 	if (conf->log)
731 		return false;
732 	return test_bit(STRIPE_BATCH_READY, &sh->state) &&
733 		!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
734 		is_full_stripe_write(sh);
735 }
736 
737 /* we only do back search */
738 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
739 {
740 	struct stripe_head *head;
741 	sector_t head_sector, tmp_sec;
742 	int hash;
743 	int dd_idx;
744 	int inc_empty_inactive_list_flag;
745 
746 	/* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
747 	tmp_sec = sh->sector;
748 	if (!sector_div(tmp_sec, conf->chunk_sectors))
749 		return;
750 	head_sector = sh->sector - STRIPE_SECTORS;
751 
752 	hash = stripe_hash_locks_hash(head_sector);
753 	spin_lock_irq(conf->hash_locks + hash);
754 	head = __find_stripe(conf, head_sector, conf->generation);
755 	if (head && !atomic_inc_not_zero(&head->count)) {
756 		spin_lock(&conf->device_lock);
757 		if (!atomic_read(&head->count)) {
758 			if (!test_bit(STRIPE_HANDLE, &head->state))
759 				atomic_inc(&conf->active_stripes);
760 			BUG_ON(list_empty(&head->lru) &&
761 			       !test_bit(STRIPE_EXPANDING, &head->state));
762 			inc_empty_inactive_list_flag = 0;
763 			if (!list_empty(conf->inactive_list + hash))
764 				inc_empty_inactive_list_flag = 1;
765 			list_del_init(&head->lru);
766 			if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
767 				atomic_inc(&conf->empty_inactive_list_nr);
768 			if (head->group) {
769 				head->group->stripes_cnt--;
770 				head->group = NULL;
771 			}
772 		}
773 		atomic_inc(&head->count);
774 		spin_unlock(&conf->device_lock);
775 	}
776 	spin_unlock_irq(conf->hash_locks + hash);
777 
778 	if (!head)
779 		return;
780 	if (!stripe_can_batch(head))
781 		goto out;
782 
783 	lock_two_stripes(head, sh);
784 	/* clear_batch_ready clear the flag */
785 	if (!stripe_can_batch(head) || !stripe_can_batch(sh))
786 		goto unlock_out;
787 
788 	if (sh->batch_head)
789 		goto unlock_out;
790 
791 	dd_idx = 0;
792 	while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
793 		dd_idx++;
794 	if (head->dev[dd_idx].towrite->bi_opf != sh->dev[dd_idx].towrite->bi_opf ||
795 	    bio_op(head->dev[dd_idx].towrite) != bio_op(sh->dev[dd_idx].towrite))
796 		goto unlock_out;
797 
798 	if (head->batch_head) {
799 		spin_lock(&head->batch_head->batch_lock);
800 		/* This batch list is already running */
801 		if (!stripe_can_batch(head)) {
802 			spin_unlock(&head->batch_head->batch_lock);
803 			goto unlock_out;
804 		}
805 
806 		/*
807 		 * at this point, head's BATCH_READY could be cleared, but we
808 		 * can still add the stripe to batch list
809 		 */
810 		list_add(&sh->batch_list, &head->batch_list);
811 		spin_unlock(&head->batch_head->batch_lock);
812 
813 		sh->batch_head = head->batch_head;
814 	} else {
815 		head->batch_head = head;
816 		sh->batch_head = head->batch_head;
817 		spin_lock(&head->batch_lock);
818 		list_add_tail(&sh->batch_list, &head->batch_list);
819 		spin_unlock(&head->batch_lock);
820 	}
821 
822 	if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
823 		if (atomic_dec_return(&conf->preread_active_stripes)
824 		    < IO_THRESHOLD)
825 			md_wakeup_thread(conf->mddev->thread);
826 
827 	if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
828 		int seq = sh->bm_seq;
829 		if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
830 		    sh->batch_head->bm_seq > seq)
831 			seq = sh->batch_head->bm_seq;
832 		set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
833 		sh->batch_head->bm_seq = seq;
834 	}
835 
836 	atomic_inc(&sh->count);
837 unlock_out:
838 	unlock_two_stripes(head, sh);
839 out:
840 	raid5_release_stripe(head);
841 }
842 
843 /* Determine if 'data_offset' or 'new_data_offset' should be used
844  * in this stripe_head.
845  */
846 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
847 {
848 	sector_t progress = conf->reshape_progress;
849 	/* Need a memory barrier to make sure we see the value
850 	 * of conf->generation, or ->data_offset that was set before
851 	 * reshape_progress was updated.
852 	 */
853 	smp_rmb();
854 	if (progress == MaxSector)
855 		return 0;
856 	if (sh->generation == conf->generation - 1)
857 		return 0;
858 	/* We are in a reshape, and this is a new-generation stripe,
859 	 * so use new_data_offset.
860 	 */
861 	return 1;
862 }
863 
864 static void
865 raid5_end_read_request(struct bio *bi);
866 static void
867 raid5_end_write_request(struct bio *bi);
868 
869 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
870 {
871 	struct r5conf *conf = sh->raid_conf;
872 	int i, disks = sh->disks;
873 	struct stripe_head *head_sh = sh;
874 
875 	might_sleep();
876 
877 	if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
878 		/* writing out phase */
879 		if (s->waiting_extra_page)
880 			return;
881 		if (r5l_write_stripe(conf->log, sh) == 0)
882 			return;
883 	} else {  /* caching phase */
884 		if (test_bit(STRIPE_LOG_TRAPPED, &sh->state)) {
885 			r5c_cache_data(conf->log, sh, s);
886 			return;
887 		}
888 	}
889 
890 	for (i = disks; i--; ) {
891 		int op, op_flags = 0;
892 		int replace_only = 0;
893 		struct bio *bi, *rbi;
894 		struct md_rdev *rdev, *rrdev = NULL;
895 
896 		sh = head_sh;
897 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
898 			op = REQ_OP_WRITE;
899 			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
900 				op_flags = REQ_FUA;
901 			if (test_bit(R5_Discard, &sh->dev[i].flags))
902 				op = REQ_OP_DISCARD;
903 		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
904 			op = REQ_OP_READ;
905 		else if (test_and_clear_bit(R5_WantReplace,
906 					    &sh->dev[i].flags)) {
907 			op = REQ_OP_WRITE;
908 			replace_only = 1;
909 		} else
910 			continue;
911 		if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
912 			op_flags |= REQ_SYNC;
913 
914 again:
915 		bi = &sh->dev[i].req;
916 		rbi = &sh->dev[i].rreq; /* For writing to replacement */
917 
918 		rcu_read_lock();
919 		rrdev = rcu_dereference(conf->disks[i].replacement);
920 		smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
921 		rdev = rcu_dereference(conf->disks[i].rdev);
922 		if (!rdev) {
923 			rdev = rrdev;
924 			rrdev = NULL;
925 		}
926 		if (op_is_write(op)) {
927 			if (replace_only)
928 				rdev = NULL;
929 			if (rdev == rrdev)
930 				/* We raced and saw duplicates */
931 				rrdev = NULL;
932 		} else {
933 			if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
934 				rdev = rrdev;
935 			rrdev = NULL;
936 		}
937 
938 		if (rdev && test_bit(Faulty, &rdev->flags))
939 			rdev = NULL;
940 		if (rdev)
941 			atomic_inc(&rdev->nr_pending);
942 		if (rrdev && test_bit(Faulty, &rrdev->flags))
943 			rrdev = NULL;
944 		if (rrdev)
945 			atomic_inc(&rrdev->nr_pending);
946 		rcu_read_unlock();
947 
948 		/* We have already checked bad blocks for reads.  Now
949 		 * need to check for writes.  We never accept write errors
950 		 * on the replacement, so we don't to check rrdev.
951 		 */
952 		while (op_is_write(op) && rdev &&
953 		       test_bit(WriteErrorSeen, &rdev->flags)) {
954 			sector_t first_bad;
955 			int bad_sectors;
956 			int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
957 					      &first_bad, &bad_sectors);
958 			if (!bad)
959 				break;
960 
961 			if (bad < 0) {
962 				set_bit(BlockedBadBlocks, &rdev->flags);
963 				if (!conf->mddev->external &&
964 				    conf->mddev->sb_flags) {
965 					/* It is very unlikely, but we might
966 					 * still need to write out the
967 					 * bad block log - better give it
968 					 * a chance*/
969 					md_check_recovery(conf->mddev);
970 				}
971 				/*
972 				 * Because md_wait_for_blocked_rdev
973 				 * will dec nr_pending, we must
974 				 * increment it first.
975 				 */
976 				atomic_inc(&rdev->nr_pending);
977 				md_wait_for_blocked_rdev(rdev, conf->mddev);
978 			} else {
979 				/* Acknowledged bad block - skip the write */
980 				rdev_dec_pending(rdev, conf->mddev);
981 				rdev = NULL;
982 			}
983 		}
984 
985 		if (rdev) {
986 			if (s->syncing || s->expanding || s->expanded
987 			    || s->replacing)
988 				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
989 
990 			set_bit(STRIPE_IO_STARTED, &sh->state);
991 
992 			bi->bi_bdev = rdev->bdev;
993 			bio_set_op_attrs(bi, op, op_flags);
994 			bi->bi_end_io = op_is_write(op)
995 				? raid5_end_write_request
996 				: raid5_end_read_request;
997 			bi->bi_private = sh;
998 
999 			pr_debug("%s: for %llu schedule op %d on disc %d\n",
1000 				__func__, (unsigned long long)sh->sector,
1001 				bi->bi_opf, i);
1002 			atomic_inc(&sh->count);
1003 			if (sh != head_sh)
1004 				atomic_inc(&head_sh->count);
1005 			if (use_new_offset(conf, sh))
1006 				bi->bi_iter.bi_sector = (sh->sector
1007 						 + rdev->new_data_offset);
1008 			else
1009 				bi->bi_iter.bi_sector = (sh->sector
1010 						 + rdev->data_offset);
1011 			if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1012 				bi->bi_opf |= REQ_NOMERGE;
1013 
1014 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1015 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1016 			sh->dev[i].vec.bv_page = sh->dev[i].page;
1017 			bi->bi_vcnt = 1;
1018 			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1019 			bi->bi_io_vec[0].bv_offset = 0;
1020 			bi->bi_iter.bi_size = STRIPE_SIZE;
1021 			/*
1022 			 * If this is discard request, set bi_vcnt 0. We don't
1023 			 * want to confuse SCSI because SCSI will replace payload
1024 			 */
1025 			if (op == REQ_OP_DISCARD)
1026 				bi->bi_vcnt = 0;
1027 			if (rrdev)
1028 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1029 
1030 			if (conf->mddev->gendisk)
1031 				trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
1032 						      bi, disk_devt(conf->mddev->gendisk),
1033 						      sh->dev[i].sector);
1034 			generic_make_request(bi);
1035 		}
1036 		if (rrdev) {
1037 			if (s->syncing || s->expanding || s->expanded
1038 			    || s->replacing)
1039 				md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1040 
1041 			set_bit(STRIPE_IO_STARTED, &sh->state);
1042 
1043 			rbi->bi_bdev = rrdev->bdev;
1044 			bio_set_op_attrs(rbi, op, op_flags);
1045 			BUG_ON(!op_is_write(op));
1046 			rbi->bi_end_io = raid5_end_write_request;
1047 			rbi->bi_private = sh;
1048 
1049 			pr_debug("%s: for %llu schedule op %d on "
1050 				 "replacement disc %d\n",
1051 				__func__, (unsigned long long)sh->sector,
1052 				rbi->bi_opf, i);
1053 			atomic_inc(&sh->count);
1054 			if (sh != head_sh)
1055 				atomic_inc(&head_sh->count);
1056 			if (use_new_offset(conf, sh))
1057 				rbi->bi_iter.bi_sector = (sh->sector
1058 						  + rrdev->new_data_offset);
1059 			else
1060 				rbi->bi_iter.bi_sector = (sh->sector
1061 						  + rrdev->data_offset);
1062 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1063 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1064 			sh->dev[i].rvec.bv_page = sh->dev[i].page;
1065 			rbi->bi_vcnt = 1;
1066 			rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1067 			rbi->bi_io_vec[0].bv_offset = 0;
1068 			rbi->bi_iter.bi_size = STRIPE_SIZE;
1069 			/*
1070 			 * If this is discard request, set bi_vcnt 0. We don't
1071 			 * want to confuse SCSI because SCSI will replace payload
1072 			 */
1073 			if (op == REQ_OP_DISCARD)
1074 				rbi->bi_vcnt = 0;
1075 			if (conf->mddev->gendisk)
1076 				trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
1077 						      rbi, disk_devt(conf->mddev->gendisk),
1078 						      sh->dev[i].sector);
1079 			generic_make_request(rbi);
1080 		}
1081 		if (!rdev && !rrdev) {
1082 			if (op_is_write(op))
1083 				set_bit(STRIPE_DEGRADED, &sh->state);
1084 			pr_debug("skip op %d on disc %d for sector %llu\n",
1085 				bi->bi_opf, i, (unsigned long long)sh->sector);
1086 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
1087 			set_bit(STRIPE_HANDLE, &sh->state);
1088 		}
1089 
1090 		if (!head_sh->batch_head)
1091 			continue;
1092 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1093 				      batch_list);
1094 		if (sh != head_sh)
1095 			goto again;
1096 	}
1097 }
1098 
1099 static struct dma_async_tx_descriptor *
1100 async_copy_data(int frombio, struct bio *bio, struct page **page,
1101 	sector_t sector, struct dma_async_tx_descriptor *tx,
1102 	struct stripe_head *sh, int no_skipcopy)
1103 {
1104 	struct bio_vec bvl;
1105 	struct bvec_iter iter;
1106 	struct page *bio_page;
1107 	int page_offset;
1108 	struct async_submit_ctl submit;
1109 	enum async_tx_flags flags = 0;
1110 
1111 	if (bio->bi_iter.bi_sector >= sector)
1112 		page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1113 	else
1114 		page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1115 
1116 	if (frombio)
1117 		flags |= ASYNC_TX_FENCE;
1118 	init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1119 
1120 	bio_for_each_segment(bvl, bio, iter) {
1121 		int len = bvl.bv_len;
1122 		int clen;
1123 		int b_offset = 0;
1124 
1125 		if (page_offset < 0) {
1126 			b_offset = -page_offset;
1127 			page_offset += b_offset;
1128 			len -= b_offset;
1129 		}
1130 
1131 		if (len > 0 && page_offset + len > STRIPE_SIZE)
1132 			clen = STRIPE_SIZE - page_offset;
1133 		else
1134 			clen = len;
1135 
1136 		if (clen > 0) {
1137 			b_offset += bvl.bv_offset;
1138 			bio_page = bvl.bv_page;
1139 			if (frombio) {
1140 				if (sh->raid_conf->skip_copy &&
1141 				    b_offset == 0 && page_offset == 0 &&
1142 				    clen == STRIPE_SIZE &&
1143 				    !no_skipcopy)
1144 					*page = bio_page;
1145 				else
1146 					tx = async_memcpy(*page, bio_page, page_offset,
1147 						  b_offset, clen, &submit);
1148 			} else
1149 				tx = async_memcpy(bio_page, *page, b_offset,
1150 						  page_offset, clen, &submit);
1151 		}
1152 		/* chain the operations */
1153 		submit.depend_tx = tx;
1154 
1155 		if (clen < len) /* hit end of page */
1156 			break;
1157 		page_offset +=  len;
1158 	}
1159 
1160 	return tx;
1161 }
1162 
1163 static void ops_complete_biofill(void *stripe_head_ref)
1164 {
1165 	struct stripe_head *sh = stripe_head_ref;
1166 	struct bio_list return_bi = BIO_EMPTY_LIST;
1167 	int i;
1168 
1169 	pr_debug("%s: stripe %llu\n", __func__,
1170 		(unsigned long long)sh->sector);
1171 
1172 	/* clear completed biofills */
1173 	for (i = sh->disks; i--; ) {
1174 		struct r5dev *dev = &sh->dev[i];
1175 
1176 		/* acknowledge completion of a biofill operation */
1177 		/* and check if we need to reply to a read request,
1178 		 * new R5_Wantfill requests are held off until
1179 		 * !STRIPE_BIOFILL_RUN
1180 		 */
1181 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1182 			struct bio *rbi, *rbi2;
1183 
1184 			BUG_ON(!dev->read);
1185 			rbi = dev->read;
1186 			dev->read = NULL;
1187 			while (rbi && rbi->bi_iter.bi_sector <
1188 				dev->sector + STRIPE_SECTORS) {
1189 				rbi2 = r5_next_bio(rbi, dev->sector);
1190 				if (!raid5_dec_bi_active_stripes(rbi))
1191 					bio_list_add(&return_bi, rbi);
1192 				rbi = rbi2;
1193 			}
1194 		}
1195 	}
1196 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1197 
1198 	return_io(&return_bi);
1199 
1200 	set_bit(STRIPE_HANDLE, &sh->state);
1201 	raid5_release_stripe(sh);
1202 }
1203 
1204 static void ops_run_biofill(struct stripe_head *sh)
1205 {
1206 	struct dma_async_tx_descriptor *tx = NULL;
1207 	struct async_submit_ctl submit;
1208 	int i;
1209 
1210 	BUG_ON(sh->batch_head);
1211 	pr_debug("%s: stripe %llu\n", __func__,
1212 		(unsigned long long)sh->sector);
1213 
1214 	for (i = sh->disks; i--; ) {
1215 		struct r5dev *dev = &sh->dev[i];
1216 		if (test_bit(R5_Wantfill, &dev->flags)) {
1217 			struct bio *rbi;
1218 			spin_lock_irq(&sh->stripe_lock);
1219 			dev->read = rbi = dev->toread;
1220 			dev->toread = NULL;
1221 			spin_unlock_irq(&sh->stripe_lock);
1222 			while (rbi && rbi->bi_iter.bi_sector <
1223 				dev->sector + STRIPE_SECTORS) {
1224 				tx = async_copy_data(0, rbi, &dev->page,
1225 						     dev->sector, tx, sh, 0);
1226 				rbi = r5_next_bio(rbi, dev->sector);
1227 			}
1228 		}
1229 	}
1230 
1231 	atomic_inc(&sh->count);
1232 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1233 	async_trigger_callback(&submit);
1234 }
1235 
1236 static void mark_target_uptodate(struct stripe_head *sh, int target)
1237 {
1238 	struct r5dev *tgt;
1239 
1240 	if (target < 0)
1241 		return;
1242 
1243 	tgt = &sh->dev[target];
1244 	set_bit(R5_UPTODATE, &tgt->flags);
1245 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1246 	clear_bit(R5_Wantcompute, &tgt->flags);
1247 }
1248 
1249 static void ops_complete_compute(void *stripe_head_ref)
1250 {
1251 	struct stripe_head *sh = stripe_head_ref;
1252 
1253 	pr_debug("%s: stripe %llu\n", __func__,
1254 		(unsigned long long)sh->sector);
1255 
1256 	/* mark the computed target(s) as uptodate */
1257 	mark_target_uptodate(sh, sh->ops.target);
1258 	mark_target_uptodate(sh, sh->ops.target2);
1259 
1260 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1261 	if (sh->check_state == check_state_compute_run)
1262 		sh->check_state = check_state_compute_result;
1263 	set_bit(STRIPE_HANDLE, &sh->state);
1264 	raid5_release_stripe(sh);
1265 }
1266 
1267 /* return a pointer to the address conversion region of the scribble buffer */
1268 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1269 				 struct raid5_percpu *percpu, int i)
1270 {
1271 	void *addr;
1272 
1273 	addr = flex_array_get(percpu->scribble, i);
1274 	return addr + sizeof(struct page *) * (sh->disks + 2);
1275 }
1276 
1277 /* return a pointer to the address conversion region of the scribble buffer */
1278 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1279 {
1280 	void *addr;
1281 
1282 	addr = flex_array_get(percpu->scribble, i);
1283 	return addr;
1284 }
1285 
1286 static struct dma_async_tx_descriptor *
1287 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1288 {
1289 	int disks = sh->disks;
1290 	struct page **xor_srcs = to_addr_page(percpu, 0);
1291 	int target = sh->ops.target;
1292 	struct r5dev *tgt = &sh->dev[target];
1293 	struct page *xor_dest = tgt->page;
1294 	int count = 0;
1295 	struct dma_async_tx_descriptor *tx;
1296 	struct async_submit_ctl submit;
1297 	int i;
1298 
1299 	BUG_ON(sh->batch_head);
1300 
1301 	pr_debug("%s: stripe %llu block: %d\n",
1302 		__func__, (unsigned long long)sh->sector, target);
1303 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1304 
1305 	for (i = disks; i--; )
1306 		if (i != target)
1307 			xor_srcs[count++] = sh->dev[i].page;
1308 
1309 	atomic_inc(&sh->count);
1310 
1311 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1312 			  ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1313 	if (unlikely(count == 1))
1314 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1315 	else
1316 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1317 
1318 	return tx;
1319 }
1320 
1321 /* set_syndrome_sources - populate source buffers for gen_syndrome
1322  * @srcs - (struct page *) array of size sh->disks
1323  * @sh - stripe_head to parse
1324  *
1325  * Populates srcs in proper layout order for the stripe and returns the
1326  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1327  * destination buffer is recorded in srcs[count] and the Q destination
1328  * is recorded in srcs[count+1]].
1329  */
1330 static int set_syndrome_sources(struct page **srcs,
1331 				struct stripe_head *sh,
1332 				int srctype)
1333 {
1334 	int disks = sh->disks;
1335 	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1336 	int d0_idx = raid6_d0(sh);
1337 	int count;
1338 	int i;
1339 
1340 	for (i = 0; i < disks; i++)
1341 		srcs[i] = NULL;
1342 
1343 	count = 0;
1344 	i = d0_idx;
1345 	do {
1346 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1347 		struct r5dev *dev = &sh->dev[i];
1348 
1349 		if (i == sh->qd_idx || i == sh->pd_idx ||
1350 		    (srctype == SYNDROME_SRC_ALL) ||
1351 		    (srctype == SYNDROME_SRC_WANT_DRAIN &&
1352 		     (test_bit(R5_Wantdrain, &dev->flags) ||
1353 		      test_bit(R5_InJournal, &dev->flags))) ||
1354 		    (srctype == SYNDROME_SRC_WRITTEN &&
1355 		     dev->written)) {
1356 			if (test_bit(R5_InJournal, &dev->flags))
1357 				srcs[slot] = sh->dev[i].orig_page;
1358 			else
1359 				srcs[slot] = sh->dev[i].page;
1360 		}
1361 		i = raid6_next_disk(i, disks);
1362 	} while (i != d0_idx);
1363 
1364 	return syndrome_disks;
1365 }
1366 
1367 static struct dma_async_tx_descriptor *
1368 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1369 {
1370 	int disks = sh->disks;
1371 	struct page **blocks = to_addr_page(percpu, 0);
1372 	int target;
1373 	int qd_idx = sh->qd_idx;
1374 	struct dma_async_tx_descriptor *tx;
1375 	struct async_submit_ctl submit;
1376 	struct r5dev *tgt;
1377 	struct page *dest;
1378 	int i;
1379 	int count;
1380 
1381 	BUG_ON(sh->batch_head);
1382 	if (sh->ops.target < 0)
1383 		target = sh->ops.target2;
1384 	else if (sh->ops.target2 < 0)
1385 		target = sh->ops.target;
1386 	else
1387 		/* we should only have one valid target */
1388 		BUG();
1389 	BUG_ON(target < 0);
1390 	pr_debug("%s: stripe %llu block: %d\n",
1391 		__func__, (unsigned long long)sh->sector, target);
1392 
1393 	tgt = &sh->dev[target];
1394 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1395 	dest = tgt->page;
1396 
1397 	atomic_inc(&sh->count);
1398 
1399 	if (target == qd_idx) {
1400 		count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1401 		blocks[count] = NULL; /* regenerating p is not necessary */
1402 		BUG_ON(blocks[count+1] != dest); /* q should already be set */
1403 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1404 				  ops_complete_compute, sh,
1405 				  to_addr_conv(sh, percpu, 0));
1406 		tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1407 	} else {
1408 		/* Compute any data- or p-drive using XOR */
1409 		count = 0;
1410 		for (i = disks; i-- ; ) {
1411 			if (i == target || i == qd_idx)
1412 				continue;
1413 			blocks[count++] = sh->dev[i].page;
1414 		}
1415 
1416 		init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1417 				  NULL, ops_complete_compute, sh,
1418 				  to_addr_conv(sh, percpu, 0));
1419 		tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1420 	}
1421 
1422 	return tx;
1423 }
1424 
1425 static struct dma_async_tx_descriptor *
1426 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1427 {
1428 	int i, count, disks = sh->disks;
1429 	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1430 	int d0_idx = raid6_d0(sh);
1431 	int faila = -1, failb = -1;
1432 	int target = sh->ops.target;
1433 	int target2 = sh->ops.target2;
1434 	struct r5dev *tgt = &sh->dev[target];
1435 	struct r5dev *tgt2 = &sh->dev[target2];
1436 	struct dma_async_tx_descriptor *tx;
1437 	struct page **blocks = to_addr_page(percpu, 0);
1438 	struct async_submit_ctl submit;
1439 
1440 	BUG_ON(sh->batch_head);
1441 	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1442 		 __func__, (unsigned long long)sh->sector, target, target2);
1443 	BUG_ON(target < 0 || target2 < 0);
1444 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1445 	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1446 
1447 	/* we need to open-code set_syndrome_sources to handle the
1448 	 * slot number conversion for 'faila' and 'failb'
1449 	 */
1450 	for (i = 0; i < disks ; i++)
1451 		blocks[i] = NULL;
1452 	count = 0;
1453 	i = d0_idx;
1454 	do {
1455 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1456 
1457 		blocks[slot] = sh->dev[i].page;
1458 
1459 		if (i == target)
1460 			faila = slot;
1461 		if (i == target2)
1462 			failb = slot;
1463 		i = raid6_next_disk(i, disks);
1464 	} while (i != d0_idx);
1465 
1466 	BUG_ON(faila == failb);
1467 	if (failb < faila)
1468 		swap(faila, failb);
1469 	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1470 		 __func__, (unsigned long long)sh->sector, faila, failb);
1471 
1472 	atomic_inc(&sh->count);
1473 
1474 	if (failb == syndrome_disks+1) {
1475 		/* Q disk is one of the missing disks */
1476 		if (faila == syndrome_disks) {
1477 			/* Missing P+Q, just recompute */
1478 			init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1479 					  ops_complete_compute, sh,
1480 					  to_addr_conv(sh, percpu, 0));
1481 			return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1482 						  STRIPE_SIZE, &submit);
1483 		} else {
1484 			struct page *dest;
1485 			int data_target;
1486 			int qd_idx = sh->qd_idx;
1487 
1488 			/* Missing D+Q: recompute D from P, then recompute Q */
1489 			if (target == qd_idx)
1490 				data_target = target2;
1491 			else
1492 				data_target = target;
1493 
1494 			count = 0;
1495 			for (i = disks; i-- ; ) {
1496 				if (i == data_target || i == qd_idx)
1497 					continue;
1498 				blocks[count++] = sh->dev[i].page;
1499 			}
1500 			dest = sh->dev[data_target].page;
1501 			init_async_submit(&submit,
1502 					  ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1503 					  NULL, NULL, NULL,
1504 					  to_addr_conv(sh, percpu, 0));
1505 			tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1506 				       &submit);
1507 
1508 			count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1509 			init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1510 					  ops_complete_compute, sh,
1511 					  to_addr_conv(sh, percpu, 0));
1512 			return async_gen_syndrome(blocks, 0, count+2,
1513 						  STRIPE_SIZE, &submit);
1514 		}
1515 	} else {
1516 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1517 				  ops_complete_compute, sh,
1518 				  to_addr_conv(sh, percpu, 0));
1519 		if (failb == syndrome_disks) {
1520 			/* We're missing D+P. */
1521 			return async_raid6_datap_recov(syndrome_disks+2,
1522 						       STRIPE_SIZE, faila,
1523 						       blocks, &submit);
1524 		} else {
1525 			/* We're missing D+D. */
1526 			return async_raid6_2data_recov(syndrome_disks+2,
1527 						       STRIPE_SIZE, faila, failb,
1528 						       blocks, &submit);
1529 		}
1530 	}
1531 }
1532 
1533 static void ops_complete_prexor(void *stripe_head_ref)
1534 {
1535 	struct stripe_head *sh = stripe_head_ref;
1536 
1537 	pr_debug("%s: stripe %llu\n", __func__,
1538 		(unsigned long long)sh->sector);
1539 
1540 	if (r5c_is_writeback(sh->raid_conf->log))
1541 		/*
1542 		 * raid5-cache write back uses orig_page during prexor.
1543 		 * After prexor, it is time to free orig_page
1544 		 */
1545 		r5c_release_extra_page(sh);
1546 }
1547 
1548 static struct dma_async_tx_descriptor *
1549 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1550 		struct dma_async_tx_descriptor *tx)
1551 {
1552 	int disks = sh->disks;
1553 	struct page **xor_srcs = to_addr_page(percpu, 0);
1554 	int count = 0, pd_idx = sh->pd_idx, i;
1555 	struct async_submit_ctl submit;
1556 
1557 	/* existing parity data subtracted */
1558 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1559 
1560 	BUG_ON(sh->batch_head);
1561 	pr_debug("%s: stripe %llu\n", __func__,
1562 		(unsigned long long)sh->sector);
1563 
1564 	for (i = disks; i--; ) {
1565 		struct r5dev *dev = &sh->dev[i];
1566 		/* Only process blocks that are known to be uptodate */
1567 		if (test_bit(R5_InJournal, &dev->flags))
1568 			xor_srcs[count++] = dev->orig_page;
1569 		else if (test_bit(R5_Wantdrain, &dev->flags))
1570 			xor_srcs[count++] = dev->page;
1571 	}
1572 
1573 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1574 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1575 	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1576 
1577 	return tx;
1578 }
1579 
1580 static struct dma_async_tx_descriptor *
1581 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1582 		struct dma_async_tx_descriptor *tx)
1583 {
1584 	struct page **blocks = to_addr_page(percpu, 0);
1585 	int count;
1586 	struct async_submit_ctl submit;
1587 
1588 	pr_debug("%s: stripe %llu\n", __func__,
1589 		(unsigned long long)sh->sector);
1590 
1591 	count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1592 
1593 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1594 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1595 	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1596 
1597 	return tx;
1598 }
1599 
1600 static struct dma_async_tx_descriptor *
1601 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1602 {
1603 	struct r5conf *conf = sh->raid_conf;
1604 	int disks = sh->disks;
1605 	int i;
1606 	struct stripe_head *head_sh = sh;
1607 
1608 	pr_debug("%s: stripe %llu\n", __func__,
1609 		(unsigned long long)sh->sector);
1610 
1611 	for (i = disks; i--; ) {
1612 		struct r5dev *dev;
1613 		struct bio *chosen;
1614 
1615 		sh = head_sh;
1616 		if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1617 			struct bio *wbi;
1618 
1619 again:
1620 			dev = &sh->dev[i];
1621 			/*
1622 			 * clear R5_InJournal, so when rewriting a page in
1623 			 * journal, it is not skipped by r5l_log_stripe()
1624 			 */
1625 			clear_bit(R5_InJournal, &dev->flags);
1626 			spin_lock_irq(&sh->stripe_lock);
1627 			chosen = dev->towrite;
1628 			dev->towrite = NULL;
1629 			sh->overwrite_disks = 0;
1630 			BUG_ON(dev->written);
1631 			wbi = dev->written = chosen;
1632 			spin_unlock_irq(&sh->stripe_lock);
1633 			WARN_ON(dev->page != dev->orig_page);
1634 
1635 			while (wbi && wbi->bi_iter.bi_sector <
1636 				dev->sector + STRIPE_SECTORS) {
1637 				if (wbi->bi_opf & REQ_FUA)
1638 					set_bit(R5_WantFUA, &dev->flags);
1639 				if (wbi->bi_opf & REQ_SYNC)
1640 					set_bit(R5_SyncIO, &dev->flags);
1641 				if (bio_op(wbi) == REQ_OP_DISCARD)
1642 					set_bit(R5_Discard, &dev->flags);
1643 				else {
1644 					tx = async_copy_data(1, wbi, &dev->page,
1645 							     dev->sector, tx, sh,
1646 							     r5c_is_writeback(conf->log));
1647 					if (dev->page != dev->orig_page &&
1648 					    !r5c_is_writeback(conf->log)) {
1649 						set_bit(R5_SkipCopy, &dev->flags);
1650 						clear_bit(R5_UPTODATE, &dev->flags);
1651 						clear_bit(R5_OVERWRITE, &dev->flags);
1652 					}
1653 				}
1654 				wbi = r5_next_bio(wbi, dev->sector);
1655 			}
1656 
1657 			if (head_sh->batch_head) {
1658 				sh = list_first_entry(&sh->batch_list,
1659 						      struct stripe_head,
1660 						      batch_list);
1661 				if (sh == head_sh)
1662 					continue;
1663 				goto again;
1664 			}
1665 		}
1666 	}
1667 
1668 	return tx;
1669 }
1670 
1671 static void ops_complete_reconstruct(void *stripe_head_ref)
1672 {
1673 	struct stripe_head *sh = stripe_head_ref;
1674 	int disks = sh->disks;
1675 	int pd_idx = sh->pd_idx;
1676 	int qd_idx = sh->qd_idx;
1677 	int i;
1678 	bool fua = false, sync = false, discard = false;
1679 
1680 	pr_debug("%s: stripe %llu\n", __func__,
1681 		(unsigned long long)sh->sector);
1682 
1683 	for (i = disks; i--; ) {
1684 		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1685 		sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1686 		discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1687 	}
1688 
1689 	for (i = disks; i--; ) {
1690 		struct r5dev *dev = &sh->dev[i];
1691 
1692 		if (dev->written || i == pd_idx || i == qd_idx) {
1693 			if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1694 				set_bit(R5_UPTODATE, &dev->flags);
1695 			if (fua)
1696 				set_bit(R5_WantFUA, &dev->flags);
1697 			if (sync)
1698 				set_bit(R5_SyncIO, &dev->flags);
1699 		}
1700 	}
1701 
1702 	if (sh->reconstruct_state == reconstruct_state_drain_run)
1703 		sh->reconstruct_state = reconstruct_state_drain_result;
1704 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1705 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1706 	else {
1707 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1708 		sh->reconstruct_state = reconstruct_state_result;
1709 	}
1710 
1711 	set_bit(STRIPE_HANDLE, &sh->state);
1712 	raid5_release_stripe(sh);
1713 }
1714 
1715 static void
1716 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1717 		     struct dma_async_tx_descriptor *tx)
1718 {
1719 	int disks = sh->disks;
1720 	struct page **xor_srcs;
1721 	struct async_submit_ctl submit;
1722 	int count, pd_idx = sh->pd_idx, i;
1723 	struct page *xor_dest;
1724 	int prexor = 0;
1725 	unsigned long flags;
1726 	int j = 0;
1727 	struct stripe_head *head_sh = sh;
1728 	int last_stripe;
1729 
1730 	pr_debug("%s: stripe %llu\n", __func__,
1731 		(unsigned long long)sh->sector);
1732 
1733 	for (i = 0; i < sh->disks; i++) {
1734 		if (pd_idx == i)
1735 			continue;
1736 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1737 			break;
1738 	}
1739 	if (i >= sh->disks) {
1740 		atomic_inc(&sh->count);
1741 		set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1742 		ops_complete_reconstruct(sh);
1743 		return;
1744 	}
1745 again:
1746 	count = 0;
1747 	xor_srcs = to_addr_page(percpu, j);
1748 	/* check if prexor is active which means only process blocks
1749 	 * that are part of a read-modify-write (written)
1750 	 */
1751 	if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1752 		prexor = 1;
1753 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1754 		for (i = disks; i--; ) {
1755 			struct r5dev *dev = &sh->dev[i];
1756 			if (head_sh->dev[i].written ||
1757 			    test_bit(R5_InJournal, &head_sh->dev[i].flags))
1758 				xor_srcs[count++] = dev->page;
1759 		}
1760 	} else {
1761 		xor_dest = sh->dev[pd_idx].page;
1762 		for (i = disks; i--; ) {
1763 			struct r5dev *dev = &sh->dev[i];
1764 			if (i != pd_idx)
1765 				xor_srcs[count++] = dev->page;
1766 		}
1767 	}
1768 
1769 	/* 1/ if we prexor'd then the dest is reused as a source
1770 	 * 2/ if we did not prexor then we are redoing the parity
1771 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1772 	 * for the synchronous xor case
1773 	 */
1774 	last_stripe = !head_sh->batch_head ||
1775 		list_first_entry(&sh->batch_list,
1776 				 struct stripe_head, batch_list) == head_sh;
1777 	if (last_stripe) {
1778 		flags = ASYNC_TX_ACK |
1779 			(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1780 
1781 		atomic_inc(&head_sh->count);
1782 		init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1783 				  to_addr_conv(sh, percpu, j));
1784 	} else {
1785 		flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1786 		init_async_submit(&submit, flags, tx, NULL, NULL,
1787 				  to_addr_conv(sh, percpu, j));
1788 	}
1789 
1790 	if (unlikely(count == 1))
1791 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1792 	else
1793 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1794 	if (!last_stripe) {
1795 		j++;
1796 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1797 				      batch_list);
1798 		goto again;
1799 	}
1800 }
1801 
1802 static void
1803 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1804 		     struct dma_async_tx_descriptor *tx)
1805 {
1806 	struct async_submit_ctl submit;
1807 	struct page **blocks;
1808 	int count, i, j = 0;
1809 	struct stripe_head *head_sh = sh;
1810 	int last_stripe;
1811 	int synflags;
1812 	unsigned long txflags;
1813 
1814 	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1815 
1816 	for (i = 0; i < sh->disks; i++) {
1817 		if (sh->pd_idx == i || sh->qd_idx == i)
1818 			continue;
1819 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1820 			break;
1821 	}
1822 	if (i >= sh->disks) {
1823 		atomic_inc(&sh->count);
1824 		set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1825 		set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1826 		ops_complete_reconstruct(sh);
1827 		return;
1828 	}
1829 
1830 again:
1831 	blocks = to_addr_page(percpu, j);
1832 
1833 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1834 		synflags = SYNDROME_SRC_WRITTEN;
1835 		txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1836 	} else {
1837 		synflags = SYNDROME_SRC_ALL;
1838 		txflags = ASYNC_TX_ACK;
1839 	}
1840 
1841 	count = set_syndrome_sources(blocks, sh, synflags);
1842 	last_stripe = !head_sh->batch_head ||
1843 		list_first_entry(&sh->batch_list,
1844 				 struct stripe_head, batch_list) == head_sh;
1845 
1846 	if (last_stripe) {
1847 		atomic_inc(&head_sh->count);
1848 		init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1849 				  head_sh, to_addr_conv(sh, percpu, j));
1850 	} else
1851 		init_async_submit(&submit, 0, tx, NULL, NULL,
1852 				  to_addr_conv(sh, percpu, j));
1853 	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1854 	if (!last_stripe) {
1855 		j++;
1856 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1857 				      batch_list);
1858 		goto again;
1859 	}
1860 }
1861 
1862 static void ops_complete_check(void *stripe_head_ref)
1863 {
1864 	struct stripe_head *sh = stripe_head_ref;
1865 
1866 	pr_debug("%s: stripe %llu\n", __func__,
1867 		(unsigned long long)sh->sector);
1868 
1869 	sh->check_state = check_state_check_result;
1870 	set_bit(STRIPE_HANDLE, &sh->state);
1871 	raid5_release_stripe(sh);
1872 }
1873 
1874 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1875 {
1876 	int disks = sh->disks;
1877 	int pd_idx = sh->pd_idx;
1878 	int qd_idx = sh->qd_idx;
1879 	struct page *xor_dest;
1880 	struct page **xor_srcs = to_addr_page(percpu, 0);
1881 	struct dma_async_tx_descriptor *tx;
1882 	struct async_submit_ctl submit;
1883 	int count;
1884 	int i;
1885 
1886 	pr_debug("%s: stripe %llu\n", __func__,
1887 		(unsigned long long)sh->sector);
1888 
1889 	BUG_ON(sh->batch_head);
1890 	count = 0;
1891 	xor_dest = sh->dev[pd_idx].page;
1892 	xor_srcs[count++] = xor_dest;
1893 	for (i = disks; i--; ) {
1894 		if (i == pd_idx || i == qd_idx)
1895 			continue;
1896 		xor_srcs[count++] = sh->dev[i].page;
1897 	}
1898 
1899 	init_async_submit(&submit, 0, NULL, NULL, NULL,
1900 			  to_addr_conv(sh, percpu, 0));
1901 	tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1902 			   &sh->ops.zero_sum_result, &submit);
1903 
1904 	atomic_inc(&sh->count);
1905 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1906 	tx = async_trigger_callback(&submit);
1907 }
1908 
1909 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1910 {
1911 	struct page **srcs = to_addr_page(percpu, 0);
1912 	struct async_submit_ctl submit;
1913 	int count;
1914 
1915 	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1916 		(unsigned long long)sh->sector, checkp);
1917 
1918 	BUG_ON(sh->batch_head);
1919 	count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
1920 	if (!checkp)
1921 		srcs[count] = NULL;
1922 
1923 	atomic_inc(&sh->count);
1924 	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1925 			  sh, to_addr_conv(sh, percpu, 0));
1926 	async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1927 			   &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1928 }
1929 
1930 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1931 {
1932 	int overlap_clear = 0, i, disks = sh->disks;
1933 	struct dma_async_tx_descriptor *tx = NULL;
1934 	struct r5conf *conf = sh->raid_conf;
1935 	int level = conf->level;
1936 	struct raid5_percpu *percpu;
1937 	unsigned long cpu;
1938 
1939 	cpu = get_cpu();
1940 	percpu = per_cpu_ptr(conf->percpu, cpu);
1941 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1942 		ops_run_biofill(sh);
1943 		overlap_clear++;
1944 	}
1945 
1946 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1947 		if (level < 6)
1948 			tx = ops_run_compute5(sh, percpu);
1949 		else {
1950 			if (sh->ops.target2 < 0 || sh->ops.target < 0)
1951 				tx = ops_run_compute6_1(sh, percpu);
1952 			else
1953 				tx = ops_run_compute6_2(sh, percpu);
1954 		}
1955 		/* terminate the chain if reconstruct is not set to be run */
1956 		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1957 			async_tx_ack(tx);
1958 	}
1959 
1960 	if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
1961 		if (level < 6)
1962 			tx = ops_run_prexor5(sh, percpu, tx);
1963 		else
1964 			tx = ops_run_prexor6(sh, percpu, tx);
1965 	}
1966 
1967 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1968 		tx = ops_run_biodrain(sh, tx);
1969 		overlap_clear++;
1970 	}
1971 
1972 	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1973 		if (level < 6)
1974 			ops_run_reconstruct5(sh, percpu, tx);
1975 		else
1976 			ops_run_reconstruct6(sh, percpu, tx);
1977 	}
1978 
1979 	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1980 		if (sh->check_state == check_state_run)
1981 			ops_run_check_p(sh, percpu);
1982 		else if (sh->check_state == check_state_run_q)
1983 			ops_run_check_pq(sh, percpu, 0);
1984 		else if (sh->check_state == check_state_run_pq)
1985 			ops_run_check_pq(sh, percpu, 1);
1986 		else
1987 			BUG();
1988 	}
1989 
1990 	if (overlap_clear && !sh->batch_head)
1991 		for (i = disks; i--; ) {
1992 			struct r5dev *dev = &sh->dev[i];
1993 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
1994 				wake_up(&sh->raid_conf->wait_for_overlap);
1995 		}
1996 	put_cpu();
1997 }
1998 
1999 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
2000 	int disks)
2001 {
2002 	struct stripe_head *sh;
2003 	int i;
2004 
2005 	sh = kmem_cache_zalloc(sc, gfp);
2006 	if (sh) {
2007 		spin_lock_init(&sh->stripe_lock);
2008 		spin_lock_init(&sh->batch_lock);
2009 		INIT_LIST_HEAD(&sh->batch_list);
2010 		INIT_LIST_HEAD(&sh->lru);
2011 		INIT_LIST_HEAD(&sh->r5c);
2012 		INIT_LIST_HEAD(&sh->log_list);
2013 		atomic_set(&sh->count, 1);
2014 		sh->log_start = MaxSector;
2015 		for (i = 0; i < disks; i++) {
2016 			struct r5dev *dev = &sh->dev[i];
2017 
2018 			bio_init(&dev->req, &dev->vec, 1);
2019 			bio_init(&dev->rreq, &dev->rvec, 1);
2020 		}
2021 	}
2022 	return sh;
2023 }
2024 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2025 {
2026 	struct stripe_head *sh;
2027 
2028 	sh = alloc_stripe(conf->slab_cache, gfp, conf->pool_size);
2029 	if (!sh)
2030 		return 0;
2031 
2032 	sh->raid_conf = conf;
2033 
2034 	if (grow_buffers(sh, gfp)) {
2035 		shrink_buffers(sh);
2036 		kmem_cache_free(conf->slab_cache, sh);
2037 		return 0;
2038 	}
2039 	sh->hash_lock_index =
2040 		conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2041 	/* we just created an active stripe so... */
2042 	atomic_inc(&conf->active_stripes);
2043 
2044 	raid5_release_stripe(sh);
2045 	conf->max_nr_stripes++;
2046 	return 1;
2047 }
2048 
2049 static int grow_stripes(struct r5conf *conf, int num)
2050 {
2051 	struct kmem_cache *sc;
2052 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
2053 
2054 	if (conf->mddev->gendisk)
2055 		sprintf(conf->cache_name[0],
2056 			"raid%d-%s", conf->level, mdname(conf->mddev));
2057 	else
2058 		sprintf(conf->cache_name[0],
2059 			"raid%d-%p", conf->level, conf->mddev);
2060 	sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
2061 
2062 	conf->active_name = 0;
2063 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
2064 			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2065 			       0, 0, NULL);
2066 	if (!sc)
2067 		return 1;
2068 	conf->slab_cache = sc;
2069 	conf->pool_size = devs;
2070 	while (num--)
2071 		if (!grow_one_stripe(conf, GFP_KERNEL))
2072 			return 1;
2073 
2074 	return 0;
2075 }
2076 
2077 /**
2078  * scribble_len - return the required size of the scribble region
2079  * @num - total number of disks in the array
2080  *
2081  * The size must be enough to contain:
2082  * 1/ a struct page pointer for each device in the array +2
2083  * 2/ room to convert each entry in (1) to its corresponding dma
2084  *    (dma_map_page()) or page (page_address()) address.
2085  *
2086  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2087  * calculate over all devices (not just the data blocks), using zeros in place
2088  * of the P and Q blocks.
2089  */
2090 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2091 {
2092 	struct flex_array *ret;
2093 	size_t len;
2094 
2095 	len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2096 	ret = flex_array_alloc(len, cnt, flags);
2097 	if (!ret)
2098 		return NULL;
2099 	/* always prealloc all elements, so no locking is required */
2100 	if (flex_array_prealloc(ret, 0, cnt, flags)) {
2101 		flex_array_free(ret);
2102 		return NULL;
2103 	}
2104 	return ret;
2105 }
2106 
2107 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2108 {
2109 	unsigned long cpu;
2110 	int err = 0;
2111 
2112 	/*
2113 	 * Never shrink. And mddev_suspend() could deadlock if this is called
2114 	 * from raid5d. In that case, scribble_disks and scribble_sectors
2115 	 * should equal to new_disks and new_sectors
2116 	 */
2117 	if (conf->scribble_disks >= new_disks &&
2118 	    conf->scribble_sectors >= new_sectors)
2119 		return 0;
2120 	mddev_suspend(conf->mddev);
2121 	get_online_cpus();
2122 	for_each_present_cpu(cpu) {
2123 		struct raid5_percpu *percpu;
2124 		struct flex_array *scribble;
2125 
2126 		percpu = per_cpu_ptr(conf->percpu, cpu);
2127 		scribble = scribble_alloc(new_disks,
2128 					  new_sectors / STRIPE_SECTORS,
2129 					  GFP_NOIO);
2130 
2131 		if (scribble) {
2132 			flex_array_free(percpu->scribble);
2133 			percpu->scribble = scribble;
2134 		} else {
2135 			err = -ENOMEM;
2136 			break;
2137 		}
2138 	}
2139 	put_online_cpus();
2140 	mddev_resume(conf->mddev);
2141 	if (!err) {
2142 		conf->scribble_disks = new_disks;
2143 		conf->scribble_sectors = new_sectors;
2144 	}
2145 	return err;
2146 }
2147 
2148 static int resize_stripes(struct r5conf *conf, int newsize)
2149 {
2150 	/* Make all the stripes able to hold 'newsize' devices.
2151 	 * New slots in each stripe get 'page' set to a new page.
2152 	 *
2153 	 * This happens in stages:
2154 	 * 1/ create a new kmem_cache and allocate the required number of
2155 	 *    stripe_heads.
2156 	 * 2/ gather all the old stripe_heads and transfer the pages across
2157 	 *    to the new stripe_heads.  This will have the side effect of
2158 	 *    freezing the array as once all stripe_heads have been collected,
2159 	 *    no IO will be possible.  Old stripe heads are freed once their
2160 	 *    pages have been transferred over, and the old kmem_cache is
2161 	 *    freed when all stripes are done.
2162 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2163 	 *    we simple return a failre status - no need to clean anything up.
2164 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
2165 	 *    If this fails, we don't bother trying the shrink the
2166 	 *    stripe_heads down again, we just leave them as they are.
2167 	 *    As each stripe_head is processed the new one is released into
2168 	 *    active service.
2169 	 *
2170 	 * Once step2 is started, we cannot afford to wait for a write,
2171 	 * so we use GFP_NOIO allocations.
2172 	 */
2173 	struct stripe_head *osh, *nsh;
2174 	LIST_HEAD(newstripes);
2175 	struct disk_info *ndisks;
2176 	int err;
2177 	struct kmem_cache *sc;
2178 	int i;
2179 	int hash, cnt;
2180 
2181 	if (newsize <= conf->pool_size)
2182 		return 0; /* never bother to shrink */
2183 
2184 	err = md_allow_write(conf->mddev);
2185 	if (err)
2186 		return err;
2187 
2188 	/* Step 1 */
2189 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2190 			       sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2191 			       0, 0, NULL);
2192 	if (!sc)
2193 		return -ENOMEM;
2194 
2195 	/* Need to ensure auto-resizing doesn't interfere */
2196 	mutex_lock(&conf->cache_size_mutex);
2197 
2198 	for (i = conf->max_nr_stripes; i; i--) {
2199 		nsh = alloc_stripe(sc, GFP_KERNEL, newsize);
2200 		if (!nsh)
2201 			break;
2202 
2203 		nsh->raid_conf = conf;
2204 		list_add(&nsh->lru, &newstripes);
2205 	}
2206 	if (i) {
2207 		/* didn't get enough, give up */
2208 		while (!list_empty(&newstripes)) {
2209 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
2210 			list_del(&nsh->lru);
2211 			kmem_cache_free(sc, nsh);
2212 		}
2213 		kmem_cache_destroy(sc);
2214 		mutex_unlock(&conf->cache_size_mutex);
2215 		return -ENOMEM;
2216 	}
2217 	/* Step 2 - Must use GFP_NOIO now.
2218 	 * OK, we have enough stripes, start collecting inactive
2219 	 * stripes and copying them over
2220 	 */
2221 	hash = 0;
2222 	cnt = 0;
2223 	list_for_each_entry(nsh, &newstripes, lru) {
2224 		lock_device_hash_lock(conf, hash);
2225 		wait_event_cmd(conf->wait_for_stripe,
2226 				    !list_empty(conf->inactive_list + hash),
2227 				    unlock_device_hash_lock(conf, hash),
2228 				    lock_device_hash_lock(conf, hash));
2229 		osh = get_free_stripe(conf, hash);
2230 		unlock_device_hash_lock(conf, hash);
2231 
2232 		for(i=0; i<conf->pool_size; i++) {
2233 			nsh->dev[i].page = osh->dev[i].page;
2234 			nsh->dev[i].orig_page = osh->dev[i].page;
2235 		}
2236 		nsh->hash_lock_index = hash;
2237 		kmem_cache_free(conf->slab_cache, osh);
2238 		cnt++;
2239 		if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2240 		    !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2241 			hash++;
2242 			cnt = 0;
2243 		}
2244 	}
2245 	kmem_cache_destroy(conf->slab_cache);
2246 
2247 	/* Step 3.
2248 	 * At this point, we are holding all the stripes so the array
2249 	 * is completely stalled, so now is a good time to resize
2250 	 * conf->disks and the scribble region
2251 	 */
2252 	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2253 	if (ndisks) {
2254 		for (i = 0; i < conf->pool_size; i++)
2255 			ndisks[i] = conf->disks[i];
2256 
2257 		for (i = conf->pool_size; i < newsize; i++) {
2258 			ndisks[i].extra_page = alloc_page(GFP_NOIO);
2259 			if (!ndisks[i].extra_page)
2260 				err = -ENOMEM;
2261 		}
2262 
2263 		if (err) {
2264 			for (i = conf->pool_size; i < newsize; i++)
2265 				if (ndisks[i].extra_page)
2266 					put_page(ndisks[i].extra_page);
2267 			kfree(ndisks);
2268 		} else {
2269 			kfree(conf->disks);
2270 			conf->disks = ndisks;
2271 		}
2272 	} else
2273 		err = -ENOMEM;
2274 
2275 	mutex_unlock(&conf->cache_size_mutex);
2276 	/* Step 4, return new stripes to service */
2277 	while(!list_empty(&newstripes)) {
2278 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
2279 		list_del_init(&nsh->lru);
2280 
2281 		for (i=conf->raid_disks; i < newsize; i++)
2282 			if (nsh->dev[i].page == NULL) {
2283 				struct page *p = alloc_page(GFP_NOIO);
2284 				nsh->dev[i].page = p;
2285 				nsh->dev[i].orig_page = p;
2286 				if (!p)
2287 					err = -ENOMEM;
2288 			}
2289 		raid5_release_stripe(nsh);
2290 	}
2291 	/* critical section pass, GFP_NOIO no longer needed */
2292 
2293 	conf->slab_cache = sc;
2294 	conf->active_name = 1-conf->active_name;
2295 	if (!err)
2296 		conf->pool_size = newsize;
2297 	return err;
2298 }
2299 
2300 static int drop_one_stripe(struct r5conf *conf)
2301 {
2302 	struct stripe_head *sh;
2303 	int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2304 
2305 	spin_lock_irq(conf->hash_locks + hash);
2306 	sh = get_free_stripe(conf, hash);
2307 	spin_unlock_irq(conf->hash_locks + hash);
2308 	if (!sh)
2309 		return 0;
2310 	BUG_ON(atomic_read(&sh->count));
2311 	shrink_buffers(sh);
2312 	kmem_cache_free(conf->slab_cache, sh);
2313 	atomic_dec(&conf->active_stripes);
2314 	conf->max_nr_stripes--;
2315 	return 1;
2316 }
2317 
2318 static void shrink_stripes(struct r5conf *conf)
2319 {
2320 	while (conf->max_nr_stripes &&
2321 	       drop_one_stripe(conf))
2322 		;
2323 
2324 	kmem_cache_destroy(conf->slab_cache);
2325 	conf->slab_cache = NULL;
2326 }
2327 
2328 static void raid5_end_read_request(struct bio * bi)
2329 {
2330 	struct stripe_head *sh = bi->bi_private;
2331 	struct r5conf *conf = sh->raid_conf;
2332 	int disks = sh->disks, i;
2333 	char b[BDEVNAME_SIZE];
2334 	struct md_rdev *rdev = NULL;
2335 	sector_t s;
2336 
2337 	for (i=0 ; i<disks; i++)
2338 		if (bi == &sh->dev[i].req)
2339 			break;
2340 
2341 	pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2342 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2343 		bi->bi_error);
2344 	if (i == disks) {
2345 		bio_reset(bi);
2346 		BUG();
2347 		return;
2348 	}
2349 	if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2350 		/* If replacement finished while this request was outstanding,
2351 		 * 'replacement' might be NULL already.
2352 		 * In that case it moved down to 'rdev'.
2353 		 * rdev is not removed until all requests are finished.
2354 		 */
2355 		rdev = conf->disks[i].replacement;
2356 	if (!rdev)
2357 		rdev = conf->disks[i].rdev;
2358 
2359 	if (use_new_offset(conf, sh))
2360 		s = sh->sector + rdev->new_data_offset;
2361 	else
2362 		s = sh->sector + rdev->data_offset;
2363 	if (!bi->bi_error) {
2364 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
2365 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2366 			/* Note that this cannot happen on a
2367 			 * replacement device.  We just fail those on
2368 			 * any error
2369 			 */
2370 			pr_info_ratelimited(
2371 				"md/raid:%s: read error corrected (%lu sectors at %llu on %s)\n",
2372 				mdname(conf->mddev), STRIPE_SECTORS,
2373 				(unsigned long long)s,
2374 				bdevname(rdev->bdev, b));
2375 			atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2376 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2377 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2378 		} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2379 			clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2380 
2381 		if (atomic_read(&rdev->read_errors))
2382 			atomic_set(&rdev->read_errors, 0);
2383 	} else {
2384 		const char *bdn = bdevname(rdev->bdev, b);
2385 		int retry = 0;
2386 		int set_bad = 0;
2387 
2388 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2389 		atomic_inc(&rdev->read_errors);
2390 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2391 			pr_warn_ratelimited(
2392 				"md/raid:%s: read error on replacement device (sector %llu on %s).\n",
2393 				mdname(conf->mddev),
2394 				(unsigned long long)s,
2395 				bdn);
2396 		else if (conf->mddev->degraded >= conf->max_degraded) {
2397 			set_bad = 1;
2398 			pr_warn_ratelimited(
2399 				"md/raid:%s: read error not correctable (sector %llu on %s).\n",
2400 				mdname(conf->mddev),
2401 				(unsigned long long)s,
2402 				bdn);
2403 		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2404 			/* Oh, no!!! */
2405 			set_bad = 1;
2406 			pr_warn_ratelimited(
2407 				"md/raid:%s: read error NOT corrected!! (sector %llu on %s).\n",
2408 				mdname(conf->mddev),
2409 				(unsigned long long)s,
2410 				bdn);
2411 		} else if (atomic_read(&rdev->read_errors)
2412 			 > conf->max_nr_stripes)
2413 			pr_warn("md/raid:%s: Too many read errors, failing device %s.\n",
2414 			       mdname(conf->mddev), bdn);
2415 		else
2416 			retry = 1;
2417 		if (set_bad && test_bit(In_sync, &rdev->flags)
2418 		    && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2419 			retry = 1;
2420 		if (retry)
2421 			if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2422 				set_bit(R5_ReadError, &sh->dev[i].flags);
2423 				clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2424 			} else
2425 				set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2426 		else {
2427 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2428 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2429 			if (!(set_bad
2430 			      && test_bit(In_sync, &rdev->flags)
2431 			      && rdev_set_badblocks(
2432 				      rdev, sh->sector, STRIPE_SECTORS, 0)))
2433 				md_error(conf->mddev, rdev);
2434 		}
2435 	}
2436 	rdev_dec_pending(rdev, conf->mddev);
2437 	bio_reset(bi);
2438 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
2439 	set_bit(STRIPE_HANDLE, &sh->state);
2440 	raid5_release_stripe(sh);
2441 }
2442 
2443 static void raid5_end_write_request(struct bio *bi)
2444 {
2445 	struct stripe_head *sh = bi->bi_private;
2446 	struct r5conf *conf = sh->raid_conf;
2447 	int disks = sh->disks, i;
2448 	struct md_rdev *uninitialized_var(rdev);
2449 	sector_t first_bad;
2450 	int bad_sectors;
2451 	int replacement = 0;
2452 
2453 	for (i = 0 ; i < disks; i++) {
2454 		if (bi == &sh->dev[i].req) {
2455 			rdev = conf->disks[i].rdev;
2456 			break;
2457 		}
2458 		if (bi == &sh->dev[i].rreq) {
2459 			rdev = conf->disks[i].replacement;
2460 			if (rdev)
2461 				replacement = 1;
2462 			else
2463 				/* rdev was removed and 'replacement'
2464 				 * replaced it.  rdev is not removed
2465 				 * until all requests are finished.
2466 				 */
2467 				rdev = conf->disks[i].rdev;
2468 			break;
2469 		}
2470 	}
2471 	pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2472 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2473 		bi->bi_error);
2474 	if (i == disks) {
2475 		bio_reset(bi);
2476 		BUG();
2477 		return;
2478 	}
2479 
2480 	if (replacement) {
2481 		if (bi->bi_error)
2482 			md_error(conf->mddev, rdev);
2483 		else if (is_badblock(rdev, sh->sector,
2484 				     STRIPE_SECTORS,
2485 				     &first_bad, &bad_sectors))
2486 			set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2487 	} else {
2488 		if (bi->bi_error) {
2489 			set_bit(STRIPE_DEGRADED, &sh->state);
2490 			set_bit(WriteErrorSeen, &rdev->flags);
2491 			set_bit(R5_WriteError, &sh->dev[i].flags);
2492 			if (!test_and_set_bit(WantReplacement, &rdev->flags))
2493 				set_bit(MD_RECOVERY_NEEDED,
2494 					&rdev->mddev->recovery);
2495 		} else if (is_badblock(rdev, sh->sector,
2496 				       STRIPE_SECTORS,
2497 				       &first_bad, &bad_sectors)) {
2498 			set_bit(R5_MadeGood, &sh->dev[i].flags);
2499 			if (test_bit(R5_ReadError, &sh->dev[i].flags))
2500 				/* That was a successful write so make
2501 				 * sure it looks like we already did
2502 				 * a re-write.
2503 				 */
2504 				set_bit(R5_ReWrite, &sh->dev[i].flags);
2505 		}
2506 	}
2507 	rdev_dec_pending(rdev, conf->mddev);
2508 
2509 	if (sh->batch_head && bi->bi_error && !replacement)
2510 		set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2511 
2512 	bio_reset(bi);
2513 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2514 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2515 	set_bit(STRIPE_HANDLE, &sh->state);
2516 	raid5_release_stripe(sh);
2517 
2518 	if (sh->batch_head && sh != sh->batch_head)
2519 		raid5_release_stripe(sh->batch_head);
2520 }
2521 
2522 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2523 {
2524 	struct r5dev *dev = &sh->dev[i];
2525 
2526 	dev->flags = 0;
2527 	dev->sector = raid5_compute_blocknr(sh, i, previous);
2528 }
2529 
2530 static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
2531 {
2532 	char b[BDEVNAME_SIZE];
2533 	struct r5conf *conf = mddev->private;
2534 	unsigned long flags;
2535 	pr_debug("raid456: error called\n");
2536 
2537 	spin_lock_irqsave(&conf->device_lock, flags);
2538 	clear_bit(In_sync, &rdev->flags);
2539 	mddev->degraded = calc_degraded(conf);
2540 	spin_unlock_irqrestore(&conf->device_lock, flags);
2541 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2542 
2543 	set_bit(Blocked, &rdev->flags);
2544 	set_bit(Faulty, &rdev->flags);
2545 	set_mask_bits(&mddev->sb_flags, 0,
2546 		      BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
2547 	pr_crit("md/raid:%s: Disk failure on %s, disabling device.\n"
2548 		"md/raid:%s: Operation continuing on %d devices.\n",
2549 		mdname(mddev),
2550 		bdevname(rdev->bdev, b),
2551 		mdname(mddev),
2552 		conf->raid_disks - mddev->degraded);
2553 }
2554 
2555 /*
2556  * Input: a 'big' sector number,
2557  * Output: index of the data and parity disk, and the sector # in them.
2558  */
2559 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2560 			      int previous, int *dd_idx,
2561 			      struct stripe_head *sh)
2562 {
2563 	sector_t stripe, stripe2;
2564 	sector_t chunk_number;
2565 	unsigned int chunk_offset;
2566 	int pd_idx, qd_idx;
2567 	int ddf_layout = 0;
2568 	sector_t new_sector;
2569 	int algorithm = previous ? conf->prev_algo
2570 				 : conf->algorithm;
2571 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2572 					 : conf->chunk_sectors;
2573 	int raid_disks = previous ? conf->previous_raid_disks
2574 				  : conf->raid_disks;
2575 	int data_disks = raid_disks - conf->max_degraded;
2576 
2577 	/* First compute the information on this sector */
2578 
2579 	/*
2580 	 * Compute the chunk number and the sector offset inside the chunk
2581 	 */
2582 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
2583 	chunk_number = r_sector;
2584 
2585 	/*
2586 	 * Compute the stripe number
2587 	 */
2588 	stripe = chunk_number;
2589 	*dd_idx = sector_div(stripe, data_disks);
2590 	stripe2 = stripe;
2591 	/*
2592 	 * Select the parity disk based on the user selected algorithm.
2593 	 */
2594 	pd_idx = qd_idx = -1;
2595 	switch(conf->level) {
2596 	case 4:
2597 		pd_idx = data_disks;
2598 		break;
2599 	case 5:
2600 		switch (algorithm) {
2601 		case ALGORITHM_LEFT_ASYMMETRIC:
2602 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2603 			if (*dd_idx >= pd_idx)
2604 				(*dd_idx)++;
2605 			break;
2606 		case ALGORITHM_RIGHT_ASYMMETRIC:
2607 			pd_idx = sector_div(stripe2, raid_disks);
2608 			if (*dd_idx >= pd_idx)
2609 				(*dd_idx)++;
2610 			break;
2611 		case ALGORITHM_LEFT_SYMMETRIC:
2612 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2613 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2614 			break;
2615 		case ALGORITHM_RIGHT_SYMMETRIC:
2616 			pd_idx = sector_div(stripe2, raid_disks);
2617 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2618 			break;
2619 		case ALGORITHM_PARITY_0:
2620 			pd_idx = 0;
2621 			(*dd_idx)++;
2622 			break;
2623 		case ALGORITHM_PARITY_N:
2624 			pd_idx = data_disks;
2625 			break;
2626 		default:
2627 			BUG();
2628 		}
2629 		break;
2630 	case 6:
2631 
2632 		switch (algorithm) {
2633 		case ALGORITHM_LEFT_ASYMMETRIC:
2634 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2635 			qd_idx = pd_idx + 1;
2636 			if (pd_idx == raid_disks-1) {
2637 				(*dd_idx)++;	/* Q D D D P */
2638 				qd_idx = 0;
2639 			} else if (*dd_idx >= pd_idx)
2640 				(*dd_idx) += 2; /* D D P Q D */
2641 			break;
2642 		case ALGORITHM_RIGHT_ASYMMETRIC:
2643 			pd_idx = sector_div(stripe2, raid_disks);
2644 			qd_idx = pd_idx + 1;
2645 			if (pd_idx == raid_disks-1) {
2646 				(*dd_idx)++;	/* Q D D D P */
2647 				qd_idx = 0;
2648 			} else if (*dd_idx >= pd_idx)
2649 				(*dd_idx) += 2; /* D D P Q D */
2650 			break;
2651 		case ALGORITHM_LEFT_SYMMETRIC:
2652 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2653 			qd_idx = (pd_idx + 1) % raid_disks;
2654 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2655 			break;
2656 		case ALGORITHM_RIGHT_SYMMETRIC:
2657 			pd_idx = sector_div(stripe2, raid_disks);
2658 			qd_idx = (pd_idx + 1) % raid_disks;
2659 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2660 			break;
2661 
2662 		case ALGORITHM_PARITY_0:
2663 			pd_idx = 0;
2664 			qd_idx = 1;
2665 			(*dd_idx) += 2;
2666 			break;
2667 		case ALGORITHM_PARITY_N:
2668 			pd_idx = data_disks;
2669 			qd_idx = data_disks + 1;
2670 			break;
2671 
2672 		case ALGORITHM_ROTATING_ZERO_RESTART:
2673 			/* Exactly the same as RIGHT_ASYMMETRIC, but or
2674 			 * of blocks for computing Q is different.
2675 			 */
2676 			pd_idx = sector_div(stripe2, raid_disks);
2677 			qd_idx = pd_idx + 1;
2678 			if (pd_idx == raid_disks-1) {
2679 				(*dd_idx)++;	/* Q D D D P */
2680 				qd_idx = 0;
2681 			} else if (*dd_idx >= pd_idx)
2682 				(*dd_idx) += 2; /* D D P Q D */
2683 			ddf_layout = 1;
2684 			break;
2685 
2686 		case ALGORITHM_ROTATING_N_RESTART:
2687 			/* Same a left_asymmetric, by first stripe is
2688 			 * D D D P Q  rather than
2689 			 * Q D D D P
2690 			 */
2691 			stripe2 += 1;
2692 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2693 			qd_idx = pd_idx + 1;
2694 			if (pd_idx == raid_disks-1) {
2695 				(*dd_idx)++;	/* Q D D D P */
2696 				qd_idx = 0;
2697 			} else if (*dd_idx >= pd_idx)
2698 				(*dd_idx) += 2; /* D D P Q D */
2699 			ddf_layout = 1;
2700 			break;
2701 
2702 		case ALGORITHM_ROTATING_N_CONTINUE:
2703 			/* Same as left_symmetric but Q is before P */
2704 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2705 			qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2706 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2707 			ddf_layout = 1;
2708 			break;
2709 
2710 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2711 			/* RAID5 left_asymmetric, with Q on last device */
2712 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2713 			if (*dd_idx >= pd_idx)
2714 				(*dd_idx)++;
2715 			qd_idx = raid_disks - 1;
2716 			break;
2717 
2718 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2719 			pd_idx = sector_div(stripe2, raid_disks-1);
2720 			if (*dd_idx >= pd_idx)
2721 				(*dd_idx)++;
2722 			qd_idx = raid_disks - 1;
2723 			break;
2724 
2725 		case ALGORITHM_LEFT_SYMMETRIC_6:
2726 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2727 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2728 			qd_idx = raid_disks - 1;
2729 			break;
2730 
2731 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2732 			pd_idx = sector_div(stripe2, raid_disks-1);
2733 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2734 			qd_idx = raid_disks - 1;
2735 			break;
2736 
2737 		case ALGORITHM_PARITY_0_6:
2738 			pd_idx = 0;
2739 			(*dd_idx)++;
2740 			qd_idx = raid_disks - 1;
2741 			break;
2742 
2743 		default:
2744 			BUG();
2745 		}
2746 		break;
2747 	}
2748 
2749 	if (sh) {
2750 		sh->pd_idx = pd_idx;
2751 		sh->qd_idx = qd_idx;
2752 		sh->ddf_layout = ddf_layout;
2753 	}
2754 	/*
2755 	 * Finally, compute the new sector number
2756 	 */
2757 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2758 	return new_sector;
2759 }
2760 
2761 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
2762 {
2763 	struct r5conf *conf = sh->raid_conf;
2764 	int raid_disks = sh->disks;
2765 	int data_disks = raid_disks - conf->max_degraded;
2766 	sector_t new_sector = sh->sector, check;
2767 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2768 					 : conf->chunk_sectors;
2769 	int algorithm = previous ? conf->prev_algo
2770 				 : conf->algorithm;
2771 	sector_t stripe;
2772 	int chunk_offset;
2773 	sector_t chunk_number;
2774 	int dummy1, dd_idx = i;
2775 	sector_t r_sector;
2776 	struct stripe_head sh2;
2777 
2778 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
2779 	stripe = new_sector;
2780 
2781 	if (i == sh->pd_idx)
2782 		return 0;
2783 	switch(conf->level) {
2784 	case 4: break;
2785 	case 5:
2786 		switch (algorithm) {
2787 		case ALGORITHM_LEFT_ASYMMETRIC:
2788 		case ALGORITHM_RIGHT_ASYMMETRIC:
2789 			if (i > sh->pd_idx)
2790 				i--;
2791 			break;
2792 		case ALGORITHM_LEFT_SYMMETRIC:
2793 		case ALGORITHM_RIGHT_SYMMETRIC:
2794 			if (i < sh->pd_idx)
2795 				i += raid_disks;
2796 			i -= (sh->pd_idx + 1);
2797 			break;
2798 		case ALGORITHM_PARITY_0:
2799 			i -= 1;
2800 			break;
2801 		case ALGORITHM_PARITY_N:
2802 			break;
2803 		default:
2804 			BUG();
2805 		}
2806 		break;
2807 	case 6:
2808 		if (i == sh->qd_idx)
2809 			return 0; /* It is the Q disk */
2810 		switch (algorithm) {
2811 		case ALGORITHM_LEFT_ASYMMETRIC:
2812 		case ALGORITHM_RIGHT_ASYMMETRIC:
2813 		case ALGORITHM_ROTATING_ZERO_RESTART:
2814 		case ALGORITHM_ROTATING_N_RESTART:
2815 			if (sh->pd_idx == raid_disks-1)
2816 				i--;	/* Q D D D P */
2817 			else if (i > sh->pd_idx)
2818 				i -= 2; /* D D P Q D */
2819 			break;
2820 		case ALGORITHM_LEFT_SYMMETRIC:
2821 		case ALGORITHM_RIGHT_SYMMETRIC:
2822 			if (sh->pd_idx == raid_disks-1)
2823 				i--; /* Q D D D P */
2824 			else {
2825 				/* D D P Q D */
2826 				if (i < sh->pd_idx)
2827 					i += raid_disks;
2828 				i -= (sh->pd_idx + 2);
2829 			}
2830 			break;
2831 		case ALGORITHM_PARITY_0:
2832 			i -= 2;
2833 			break;
2834 		case ALGORITHM_PARITY_N:
2835 			break;
2836 		case ALGORITHM_ROTATING_N_CONTINUE:
2837 			/* Like left_symmetric, but P is before Q */
2838 			if (sh->pd_idx == 0)
2839 				i--;	/* P D D D Q */
2840 			else {
2841 				/* D D Q P D */
2842 				if (i < sh->pd_idx)
2843 					i += raid_disks;
2844 				i -= (sh->pd_idx + 1);
2845 			}
2846 			break;
2847 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2848 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2849 			if (i > sh->pd_idx)
2850 				i--;
2851 			break;
2852 		case ALGORITHM_LEFT_SYMMETRIC_6:
2853 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2854 			if (i < sh->pd_idx)
2855 				i += data_disks + 1;
2856 			i -= (sh->pd_idx + 1);
2857 			break;
2858 		case ALGORITHM_PARITY_0_6:
2859 			i -= 1;
2860 			break;
2861 		default:
2862 			BUG();
2863 		}
2864 		break;
2865 	}
2866 
2867 	chunk_number = stripe * data_disks + i;
2868 	r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2869 
2870 	check = raid5_compute_sector(conf, r_sector,
2871 				     previous, &dummy1, &sh2);
2872 	if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2873 		|| sh2.qd_idx != sh->qd_idx) {
2874 		pr_warn("md/raid:%s: compute_blocknr: map not correct\n",
2875 			mdname(conf->mddev));
2876 		return 0;
2877 	}
2878 	return r_sector;
2879 }
2880 
2881 static void
2882 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2883 			 int rcw, int expand)
2884 {
2885 	int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
2886 	struct r5conf *conf = sh->raid_conf;
2887 	int level = conf->level;
2888 
2889 	if (rcw) {
2890 		/*
2891 		 * In some cases, handle_stripe_dirtying initially decided to
2892 		 * run rmw and allocates extra page for prexor. However, rcw is
2893 		 * cheaper later on. We need to free the extra page now,
2894 		 * because we won't be able to do that in ops_complete_prexor().
2895 		 */
2896 		r5c_release_extra_page(sh);
2897 
2898 		for (i = disks; i--; ) {
2899 			struct r5dev *dev = &sh->dev[i];
2900 
2901 			if (dev->towrite) {
2902 				set_bit(R5_LOCKED, &dev->flags);
2903 				set_bit(R5_Wantdrain, &dev->flags);
2904 				if (!expand)
2905 					clear_bit(R5_UPTODATE, &dev->flags);
2906 				s->locked++;
2907 			} else if (test_bit(R5_InJournal, &dev->flags)) {
2908 				set_bit(R5_LOCKED, &dev->flags);
2909 				s->locked++;
2910 			}
2911 		}
2912 		/* if we are not expanding this is a proper write request, and
2913 		 * there will be bios with new data to be drained into the
2914 		 * stripe cache
2915 		 */
2916 		if (!expand) {
2917 			if (!s->locked)
2918 				/* False alarm, nothing to do */
2919 				return;
2920 			sh->reconstruct_state = reconstruct_state_drain_run;
2921 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2922 		} else
2923 			sh->reconstruct_state = reconstruct_state_run;
2924 
2925 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2926 
2927 		if (s->locked + conf->max_degraded == disks)
2928 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2929 				atomic_inc(&conf->pending_full_writes);
2930 	} else {
2931 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2932 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2933 		BUG_ON(level == 6 &&
2934 			(!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
2935 			   test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
2936 
2937 		for (i = disks; i--; ) {
2938 			struct r5dev *dev = &sh->dev[i];
2939 			if (i == pd_idx || i == qd_idx)
2940 				continue;
2941 
2942 			if (dev->towrite &&
2943 			    (test_bit(R5_UPTODATE, &dev->flags) ||
2944 			     test_bit(R5_Wantcompute, &dev->flags))) {
2945 				set_bit(R5_Wantdrain, &dev->flags);
2946 				set_bit(R5_LOCKED, &dev->flags);
2947 				clear_bit(R5_UPTODATE, &dev->flags);
2948 				s->locked++;
2949 			} else if (test_bit(R5_InJournal, &dev->flags)) {
2950 				set_bit(R5_LOCKED, &dev->flags);
2951 				s->locked++;
2952 			}
2953 		}
2954 		if (!s->locked)
2955 			/* False alarm - nothing to do */
2956 			return;
2957 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2958 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2959 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2960 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2961 	}
2962 
2963 	/* keep the parity disk(s) locked while asynchronous operations
2964 	 * are in flight
2965 	 */
2966 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2967 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2968 	s->locked++;
2969 
2970 	if (level == 6) {
2971 		int qd_idx = sh->qd_idx;
2972 		struct r5dev *dev = &sh->dev[qd_idx];
2973 
2974 		set_bit(R5_LOCKED, &dev->flags);
2975 		clear_bit(R5_UPTODATE, &dev->flags);
2976 		s->locked++;
2977 	}
2978 
2979 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2980 		__func__, (unsigned long long)sh->sector,
2981 		s->locked, s->ops_request);
2982 }
2983 
2984 /*
2985  * Each stripe/dev can have one or more bion attached.
2986  * toread/towrite point to the first in a chain.
2987  * The bi_next chain must be in order.
2988  */
2989 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
2990 			  int forwrite, int previous)
2991 {
2992 	struct bio **bip;
2993 	struct r5conf *conf = sh->raid_conf;
2994 	int firstwrite=0;
2995 
2996 	pr_debug("adding bi b#%llu to stripe s#%llu\n",
2997 		(unsigned long long)bi->bi_iter.bi_sector,
2998 		(unsigned long long)sh->sector);
2999 
3000 	/*
3001 	 * If several bio share a stripe. The bio bi_phys_segments acts as a
3002 	 * reference count to avoid race. The reference count should already be
3003 	 * increased before this function is called (for example, in
3004 	 * raid5_make_request()), so other bio sharing this stripe will not free the
3005 	 * stripe. If a stripe is owned by one stripe, the stripe lock will
3006 	 * protect it.
3007 	 */
3008 	spin_lock_irq(&sh->stripe_lock);
3009 	/* Don't allow new IO added to stripes in batch list */
3010 	if (sh->batch_head)
3011 		goto overlap;
3012 	if (forwrite) {
3013 		bip = &sh->dev[dd_idx].towrite;
3014 		if (*bip == NULL)
3015 			firstwrite = 1;
3016 	} else
3017 		bip = &sh->dev[dd_idx].toread;
3018 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
3019 		if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
3020 			goto overlap;
3021 		bip = & (*bip)->bi_next;
3022 	}
3023 	if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
3024 		goto overlap;
3025 
3026 	if (!forwrite || previous)
3027 		clear_bit(STRIPE_BATCH_READY, &sh->state);
3028 
3029 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3030 	if (*bip)
3031 		bi->bi_next = *bip;
3032 	*bip = bi;
3033 	raid5_inc_bi_active_stripes(bi);
3034 
3035 	if (forwrite) {
3036 		/* check if page is covered */
3037 		sector_t sector = sh->dev[dd_idx].sector;
3038 		for (bi=sh->dev[dd_idx].towrite;
3039 		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
3040 			     bi && bi->bi_iter.bi_sector <= sector;
3041 		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
3042 			if (bio_end_sector(bi) >= sector)
3043 				sector = bio_end_sector(bi);
3044 		}
3045 		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
3046 			if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3047 				sh->overwrite_disks++;
3048 	}
3049 
3050 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3051 		(unsigned long long)(*bip)->bi_iter.bi_sector,
3052 		(unsigned long long)sh->sector, dd_idx);
3053 
3054 	if (conf->mddev->bitmap && firstwrite) {
3055 		/* Cannot hold spinlock over bitmap_startwrite,
3056 		 * but must ensure this isn't added to a batch until
3057 		 * we have added to the bitmap and set bm_seq.
3058 		 * So set STRIPE_BITMAP_PENDING to prevent
3059 		 * batching.
3060 		 * If multiple add_stripe_bio() calls race here they
3061 		 * much all set STRIPE_BITMAP_PENDING.  So only the first one
3062 		 * to complete "bitmap_startwrite" gets to set
3063 		 * STRIPE_BIT_DELAY.  This is important as once a stripe
3064 		 * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3065 		 * any more.
3066 		 */
3067 		set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3068 		spin_unlock_irq(&sh->stripe_lock);
3069 		bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3070 				  STRIPE_SECTORS, 0);
3071 		spin_lock_irq(&sh->stripe_lock);
3072 		clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3073 		if (!sh->batch_head) {
3074 			sh->bm_seq = conf->seq_flush+1;
3075 			set_bit(STRIPE_BIT_DELAY, &sh->state);
3076 		}
3077 	}
3078 	spin_unlock_irq(&sh->stripe_lock);
3079 
3080 	if (stripe_can_batch(sh))
3081 		stripe_add_to_batch_list(conf, sh);
3082 	return 1;
3083 
3084  overlap:
3085 	set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3086 	spin_unlock_irq(&sh->stripe_lock);
3087 	return 0;
3088 }
3089 
3090 static void end_reshape(struct r5conf *conf);
3091 
3092 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3093 			    struct stripe_head *sh)
3094 {
3095 	int sectors_per_chunk =
3096 		previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3097 	int dd_idx;
3098 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
3099 	int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3100 
3101 	raid5_compute_sector(conf,
3102 			     stripe * (disks - conf->max_degraded)
3103 			     *sectors_per_chunk + chunk_offset,
3104 			     previous,
3105 			     &dd_idx, sh);
3106 }
3107 
3108 static void
3109 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3110 				struct stripe_head_state *s, int disks,
3111 				struct bio_list *return_bi)
3112 {
3113 	int i;
3114 	BUG_ON(sh->batch_head);
3115 	for (i = disks; i--; ) {
3116 		struct bio *bi;
3117 		int bitmap_end = 0;
3118 
3119 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3120 			struct md_rdev *rdev;
3121 			rcu_read_lock();
3122 			rdev = rcu_dereference(conf->disks[i].rdev);
3123 			if (rdev && test_bit(In_sync, &rdev->flags) &&
3124 			    !test_bit(Faulty, &rdev->flags))
3125 				atomic_inc(&rdev->nr_pending);
3126 			else
3127 				rdev = NULL;
3128 			rcu_read_unlock();
3129 			if (rdev) {
3130 				if (!rdev_set_badblocks(
3131 					    rdev,
3132 					    sh->sector,
3133 					    STRIPE_SECTORS, 0))
3134 					md_error(conf->mddev, rdev);
3135 				rdev_dec_pending(rdev, conf->mddev);
3136 			}
3137 		}
3138 		spin_lock_irq(&sh->stripe_lock);
3139 		/* fail all writes first */
3140 		bi = sh->dev[i].towrite;
3141 		sh->dev[i].towrite = NULL;
3142 		sh->overwrite_disks = 0;
3143 		spin_unlock_irq(&sh->stripe_lock);
3144 		if (bi)
3145 			bitmap_end = 1;
3146 
3147 		r5l_stripe_write_finished(sh);
3148 
3149 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3150 			wake_up(&conf->wait_for_overlap);
3151 
3152 		while (bi && bi->bi_iter.bi_sector <
3153 			sh->dev[i].sector + STRIPE_SECTORS) {
3154 			struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3155 
3156 			bi->bi_error = -EIO;
3157 			if (!raid5_dec_bi_active_stripes(bi)) {
3158 				md_write_end(conf->mddev);
3159 				bio_list_add(return_bi, bi);
3160 			}
3161 			bi = nextbi;
3162 		}
3163 		if (bitmap_end)
3164 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3165 				STRIPE_SECTORS, 0, 0);
3166 		bitmap_end = 0;
3167 		/* and fail all 'written' */
3168 		bi = sh->dev[i].written;
3169 		sh->dev[i].written = NULL;
3170 		if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3171 			WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3172 			sh->dev[i].page = sh->dev[i].orig_page;
3173 		}
3174 
3175 		if (bi) bitmap_end = 1;
3176 		while (bi && bi->bi_iter.bi_sector <
3177 		       sh->dev[i].sector + STRIPE_SECTORS) {
3178 			struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3179 
3180 			bi->bi_error = -EIO;
3181 			if (!raid5_dec_bi_active_stripes(bi)) {
3182 				md_write_end(conf->mddev);
3183 				bio_list_add(return_bi, bi);
3184 			}
3185 			bi = bi2;
3186 		}
3187 
3188 		/* fail any reads if this device is non-operational and
3189 		 * the data has not reached the cache yet.
3190 		 */
3191 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3192 		    s->failed > conf->max_degraded &&
3193 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3194 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
3195 			spin_lock_irq(&sh->stripe_lock);
3196 			bi = sh->dev[i].toread;
3197 			sh->dev[i].toread = NULL;
3198 			spin_unlock_irq(&sh->stripe_lock);
3199 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3200 				wake_up(&conf->wait_for_overlap);
3201 			if (bi)
3202 				s->to_read--;
3203 			while (bi && bi->bi_iter.bi_sector <
3204 			       sh->dev[i].sector + STRIPE_SECTORS) {
3205 				struct bio *nextbi =
3206 					r5_next_bio(bi, sh->dev[i].sector);
3207 
3208 				bi->bi_error = -EIO;
3209 				if (!raid5_dec_bi_active_stripes(bi))
3210 					bio_list_add(return_bi, bi);
3211 				bi = nextbi;
3212 			}
3213 		}
3214 		if (bitmap_end)
3215 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3216 					STRIPE_SECTORS, 0, 0);
3217 		/* If we were in the middle of a write the parity block might
3218 		 * still be locked - so just clear all R5_LOCKED flags
3219 		 */
3220 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
3221 	}
3222 	s->to_write = 0;
3223 	s->written = 0;
3224 
3225 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3226 		if (atomic_dec_and_test(&conf->pending_full_writes))
3227 			md_wakeup_thread(conf->mddev->thread);
3228 }
3229 
3230 static void
3231 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3232 		   struct stripe_head_state *s)
3233 {
3234 	int abort = 0;
3235 	int i;
3236 
3237 	BUG_ON(sh->batch_head);
3238 	clear_bit(STRIPE_SYNCING, &sh->state);
3239 	if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3240 		wake_up(&conf->wait_for_overlap);
3241 	s->syncing = 0;
3242 	s->replacing = 0;
3243 	/* There is nothing more to do for sync/check/repair.
3244 	 * Don't even need to abort as that is handled elsewhere
3245 	 * if needed, and not always wanted e.g. if there is a known
3246 	 * bad block here.
3247 	 * For recover/replace we need to record a bad block on all
3248 	 * non-sync devices, or abort the recovery
3249 	 */
3250 	if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3251 		/* During recovery devices cannot be removed, so
3252 		 * locking and refcounting of rdevs is not needed
3253 		 */
3254 		rcu_read_lock();
3255 		for (i = 0; i < conf->raid_disks; i++) {
3256 			struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
3257 			if (rdev
3258 			    && !test_bit(Faulty, &rdev->flags)
3259 			    && !test_bit(In_sync, &rdev->flags)
3260 			    && !rdev_set_badblocks(rdev, sh->sector,
3261 						   STRIPE_SECTORS, 0))
3262 				abort = 1;
3263 			rdev = rcu_dereference(conf->disks[i].replacement);
3264 			if (rdev
3265 			    && !test_bit(Faulty, &rdev->flags)
3266 			    && !test_bit(In_sync, &rdev->flags)
3267 			    && !rdev_set_badblocks(rdev, sh->sector,
3268 						   STRIPE_SECTORS, 0))
3269 				abort = 1;
3270 		}
3271 		rcu_read_unlock();
3272 		if (abort)
3273 			conf->recovery_disabled =
3274 				conf->mddev->recovery_disabled;
3275 	}
3276 	md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3277 }
3278 
3279 static int want_replace(struct stripe_head *sh, int disk_idx)
3280 {
3281 	struct md_rdev *rdev;
3282 	int rv = 0;
3283 
3284 	rcu_read_lock();
3285 	rdev = rcu_dereference(sh->raid_conf->disks[disk_idx].replacement);
3286 	if (rdev
3287 	    && !test_bit(Faulty, &rdev->flags)
3288 	    && !test_bit(In_sync, &rdev->flags)
3289 	    && (rdev->recovery_offset <= sh->sector
3290 		|| rdev->mddev->recovery_cp <= sh->sector))
3291 		rv = 1;
3292 	rcu_read_unlock();
3293 	return rv;
3294 }
3295 
3296 /* fetch_block - checks the given member device to see if its data needs
3297  * to be read or computed to satisfy a request.
3298  *
3299  * Returns 1 when no more member devices need to be checked, otherwise returns
3300  * 0 to tell the loop in handle_stripe_fill to continue
3301  */
3302 
3303 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3304 			   int disk_idx, int disks)
3305 {
3306 	struct r5dev *dev = &sh->dev[disk_idx];
3307 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3308 				  &sh->dev[s->failed_num[1]] };
3309 	int i;
3310 
3311 
3312 	if (test_bit(R5_LOCKED, &dev->flags) ||
3313 	    test_bit(R5_UPTODATE, &dev->flags))
3314 		/* No point reading this as we already have it or have
3315 		 * decided to get it.
3316 		 */
3317 		return 0;
3318 
3319 	if (dev->toread ||
3320 	    (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3321 		/* We need this block to directly satisfy a request */
3322 		return 1;
3323 
3324 	if (s->syncing || s->expanding ||
3325 	    (s->replacing && want_replace(sh, disk_idx)))
3326 		/* When syncing, or expanding we read everything.
3327 		 * When replacing, we need the replaced block.
3328 		 */
3329 		return 1;
3330 
3331 	if ((s->failed >= 1 && fdev[0]->toread) ||
3332 	    (s->failed >= 2 && fdev[1]->toread))
3333 		/* If we want to read from a failed device, then
3334 		 * we need to actually read every other device.
3335 		 */
3336 		return 1;
3337 
3338 	/* Sometimes neither read-modify-write nor reconstruct-write
3339 	 * cycles can work.  In those cases we read every block we
3340 	 * can.  Then the parity-update is certain to have enough to
3341 	 * work with.
3342 	 * This can only be a problem when we need to write something,
3343 	 * and some device has failed.  If either of those tests
3344 	 * fail we need look no further.
3345 	 */
3346 	if (!s->failed || !s->to_write)
3347 		return 0;
3348 
3349 	if (test_bit(R5_Insync, &dev->flags) &&
3350 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3351 		/* Pre-reads at not permitted until after short delay
3352 		 * to gather multiple requests.  However if this
3353 		 * device is no Insync, the block could only be be computed
3354 		 * and there is no need to delay that.
3355 		 */
3356 		return 0;
3357 
3358 	for (i = 0; i < s->failed && i < 2; i++) {
3359 		if (fdev[i]->towrite &&
3360 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3361 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3362 			/* If we have a partial write to a failed
3363 			 * device, then we will need to reconstruct
3364 			 * the content of that device, so all other
3365 			 * devices must be read.
3366 			 */
3367 			return 1;
3368 	}
3369 
3370 	/* If we are forced to do a reconstruct-write, either because
3371 	 * the current RAID6 implementation only supports that, or
3372 	 * or because parity cannot be trusted and we are currently
3373 	 * recovering it, there is extra need to be careful.
3374 	 * If one of the devices that we would need to read, because
3375 	 * it is not being overwritten (and maybe not written at all)
3376 	 * is missing/faulty, then we need to read everything we can.
3377 	 */
3378 	if (sh->raid_conf->level != 6 &&
3379 	    sh->sector < sh->raid_conf->mddev->recovery_cp)
3380 		/* reconstruct-write isn't being forced */
3381 		return 0;
3382 	for (i = 0; i < s->failed && i < 2; i++) {
3383 		if (s->failed_num[i] != sh->pd_idx &&
3384 		    s->failed_num[i] != sh->qd_idx &&
3385 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3386 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3387 			return 1;
3388 	}
3389 
3390 	return 0;
3391 }
3392 
3393 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3394 		       int disk_idx, int disks)
3395 {
3396 	struct r5dev *dev = &sh->dev[disk_idx];
3397 
3398 	/* is the data in this block needed, and can we get it? */
3399 	if (need_this_block(sh, s, disk_idx, disks)) {
3400 		/* we would like to get this block, possibly by computing it,
3401 		 * otherwise read it if the backing disk is insync
3402 		 */
3403 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3404 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
3405 		BUG_ON(sh->batch_head);
3406 		if ((s->uptodate == disks - 1) &&
3407 		    (s->failed && (disk_idx == s->failed_num[0] ||
3408 				   disk_idx == s->failed_num[1]))) {
3409 			/* have disk failed, and we're requested to fetch it;
3410 			 * do compute it
3411 			 */
3412 			pr_debug("Computing stripe %llu block %d\n",
3413 			       (unsigned long long)sh->sector, disk_idx);
3414 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3415 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3416 			set_bit(R5_Wantcompute, &dev->flags);
3417 			sh->ops.target = disk_idx;
3418 			sh->ops.target2 = -1; /* no 2nd target */
3419 			s->req_compute = 1;
3420 			/* Careful: from this point on 'uptodate' is in the eye
3421 			 * of raid_run_ops which services 'compute' operations
3422 			 * before writes. R5_Wantcompute flags a block that will
3423 			 * be R5_UPTODATE by the time it is needed for a
3424 			 * subsequent operation.
3425 			 */
3426 			s->uptodate++;
3427 			return 1;
3428 		} else if (s->uptodate == disks-2 && s->failed >= 2) {
3429 			/* Computing 2-failure is *very* expensive; only
3430 			 * do it if failed >= 2
3431 			 */
3432 			int other;
3433 			for (other = disks; other--; ) {
3434 				if (other == disk_idx)
3435 					continue;
3436 				if (!test_bit(R5_UPTODATE,
3437 				      &sh->dev[other].flags))
3438 					break;
3439 			}
3440 			BUG_ON(other < 0);
3441 			pr_debug("Computing stripe %llu blocks %d,%d\n",
3442 			       (unsigned long long)sh->sector,
3443 			       disk_idx, other);
3444 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3445 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3446 			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3447 			set_bit(R5_Wantcompute, &sh->dev[other].flags);
3448 			sh->ops.target = disk_idx;
3449 			sh->ops.target2 = other;
3450 			s->uptodate += 2;
3451 			s->req_compute = 1;
3452 			return 1;
3453 		} else if (test_bit(R5_Insync, &dev->flags)) {
3454 			set_bit(R5_LOCKED, &dev->flags);
3455 			set_bit(R5_Wantread, &dev->flags);
3456 			s->locked++;
3457 			pr_debug("Reading block %d (sync=%d)\n",
3458 				disk_idx, s->syncing);
3459 		}
3460 	}
3461 
3462 	return 0;
3463 }
3464 
3465 /**
3466  * handle_stripe_fill - read or compute data to satisfy pending requests.
3467  */
3468 static void handle_stripe_fill(struct stripe_head *sh,
3469 			       struct stripe_head_state *s,
3470 			       int disks)
3471 {
3472 	int i;
3473 
3474 	/* look for blocks to read/compute, skip this if a compute
3475 	 * is already in flight, or if the stripe contents are in the
3476 	 * midst of changing due to a write
3477 	 */
3478 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3479 	    !sh->reconstruct_state)
3480 		for (i = disks; i--; )
3481 			if (fetch_block(sh, s, i, disks))
3482 				break;
3483 	set_bit(STRIPE_HANDLE, &sh->state);
3484 }
3485 
3486 static void break_stripe_batch_list(struct stripe_head *head_sh,
3487 				    unsigned long handle_flags);
3488 /* handle_stripe_clean_event
3489  * any written block on an uptodate or failed drive can be returned.
3490  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3491  * never LOCKED, so we don't need to test 'failed' directly.
3492  */
3493 static void handle_stripe_clean_event(struct r5conf *conf,
3494 	struct stripe_head *sh, int disks, struct bio_list *return_bi)
3495 {
3496 	int i;
3497 	struct r5dev *dev;
3498 	int discard_pending = 0;
3499 	struct stripe_head *head_sh = sh;
3500 	bool do_endio = false;
3501 
3502 	for (i = disks; i--; )
3503 		if (sh->dev[i].written) {
3504 			dev = &sh->dev[i];
3505 			if (!test_bit(R5_LOCKED, &dev->flags) &&
3506 			    (test_bit(R5_UPTODATE, &dev->flags) ||
3507 			     test_bit(R5_Discard, &dev->flags) ||
3508 			     test_bit(R5_SkipCopy, &dev->flags))) {
3509 				/* We can return any write requests */
3510 				struct bio *wbi, *wbi2;
3511 				pr_debug("Return write for disc %d\n", i);
3512 				if (test_and_clear_bit(R5_Discard, &dev->flags))
3513 					clear_bit(R5_UPTODATE, &dev->flags);
3514 				if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3515 					WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3516 				}
3517 				do_endio = true;
3518 
3519 returnbi:
3520 				dev->page = dev->orig_page;
3521 				wbi = dev->written;
3522 				dev->written = NULL;
3523 				while (wbi && wbi->bi_iter.bi_sector <
3524 					dev->sector + STRIPE_SECTORS) {
3525 					wbi2 = r5_next_bio(wbi, dev->sector);
3526 					if (!raid5_dec_bi_active_stripes(wbi)) {
3527 						md_write_end(conf->mddev);
3528 						bio_list_add(return_bi, wbi);
3529 					}
3530 					wbi = wbi2;
3531 				}
3532 				bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3533 						STRIPE_SECTORS,
3534 					 !test_bit(STRIPE_DEGRADED, &sh->state),
3535 						0);
3536 				if (head_sh->batch_head) {
3537 					sh = list_first_entry(&sh->batch_list,
3538 							      struct stripe_head,
3539 							      batch_list);
3540 					if (sh != head_sh) {
3541 						dev = &sh->dev[i];
3542 						goto returnbi;
3543 					}
3544 				}
3545 				sh = head_sh;
3546 				dev = &sh->dev[i];
3547 			} else if (test_bit(R5_Discard, &dev->flags))
3548 				discard_pending = 1;
3549 		}
3550 
3551 	r5l_stripe_write_finished(sh);
3552 
3553 	if (!discard_pending &&
3554 	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3555 		int hash;
3556 		clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3557 		clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3558 		if (sh->qd_idx >= 0) {
3559 			clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3560 			clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3561 		}
3562 		/* now that discard is done we can proceed with any sync */
3563 		clear_bit(STRIPE_DISCARD, &sh->state);
3564 		/*
3565 		 * SCSI discard will change some bio fields and the stripe has
3566 		 * no updated data, so remove it from hash list and the stripe
3567 		 * will be reinitialized
3568 		 */
3569 unhash:
3570 		hash = sh->hash_lock_index;
3571 		spin_lock_irq(conf->hash_locks + hash);
3572 		remove_hash(sh);
3573 		spin_unlock_irq(conf->hash_locks + hash);
3574 		if (head_sh->batch_head) {
3575 			sh = list_first_entry(&sh->batch_list,
3576 					      struct stripe_head, batch_list);
3577 			if (sh != head_sh)
3578 					goto unhash;
3579 		}
3580 		sh = head_sh;
3581 
3582 		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3583 			set_bit(STRIPE_HANDLE, &sh->state);
3584 
3585 	}
3586 
3587 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3588 		if (atomic_dec_and_test(&conf->pending_full_writes))
3589 			md_wakeup_thread(conf->mddev->thread);
3590 
3591 	if (head_sh->batch_head && do_endio)
3592 		break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3593 }
3594 
3595 static int handle_stripe_dirtying(struct r5conf *conf,
3596 				  struct stripe_head *sh,
3597 				  struct stripe_head_state *s,
3598 				  int disks)
3599 {
3600 	int rmw = 0, rcw = 0, i;
3601 	sector_t recovery_cp = conf->mddev->recovery_cp;
3602 
3603 	/* Check whether resync is now happening or should start.
3604 	 * If yes, then the array is dirty (after unclean shutdown or
3605 	 * initial creation), so parity in some stripes might be inconsistent.
3606 	 * In this case, we need to always do reconstruct-write, to ensure
3607 	 * that in case of drive failure or read-error correction, we
3608 	 * generate correct data from the parity.
3609 	 */
3610 	if (conf->rmw_level == PARITY_DISABLE_RMW ||
3611 	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3612 	     s->failed == 0)) {
3613 		/* Calculate the real rcw later - for now make it
3614 		 * look like rcw is cheaper
3615 		 */
3616 		rcw = 1; rmw = 2;
3617 		pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3618 			 conf->rmw_level, (unsigned long long)recovery_cp,
3619 			 (unsigned long long)sh->sector);
3620 	} else for (i = disks; i--; ) {
3621 		/* would I have to read this buffer for read_modify_write */
3622 		struct r5dev *dev = &sh->dev[i];
3623 		if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx ||
3624 		     test_bit(R5_InJournal, &dev->flags)) &&
3625 		    !test_bit(R5_LOCKED, &dev->flags) &&
3626 		    !((test_bit(R5_UPTODATE, &dev->flags) &&
3627 		       (!test_bit(R5_InJournal, &dev->flags) ||
3628 			dev->page != dev->orig_page)) ||
3629 		      test_bit(R5_Wantcompute, &dev->flags))) {
3630 			if (test_bit(R5_Insync, &dev->flags))
3631 				rmw++;
3632 			else
3633 				rmw += 2*disks;  /* cannot read it */
3634 		}
3635 		/* Would I have to read this buffer for reconstruct_write */
3636 		if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3637 		    i != sh->pd_idx && i != sh->qd_idx &&
3638 		    !test_bit(R5_LOCKED, &dev->flags) &&
3639 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
3640 		      test_bit(R5_InJournal, &dev->flags) ||
3641 		      test_bit(R5_Wantcompute, &dev->flags))) {
3642 			if (test_bit(R5_Insync, &dev->flags))
3643 				rcw++;
3644 			else
3645 				rcw += 2*disks;
3646 		}
3647 	}
3648 
3649 	pr_debug("for sector %llu, rmw=%d rcw=%d\n",
3650 		(unsigned long long)sh->sector, rmw, rcw);
3651 	set_bit(STRIPE_HANDLE, &sh->state);
3652 	if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
3653 		/* prefer read-modify-write, but need to get some data */
3654 		if (conf->mddev->queue)
3655 			blk_add_trace_msg(conf->mddev->queue,
3656 					  "raid5 rmw %llu %d",
3657 					  (unsigned long long)sh->sector, rmw);
3658 		for (i = disks; i--; ) {
3659 			struct r5dev *dev = &sh->dev[i];
3660 			if (test_bit(R5_InJournal, &dev->flags) &&
3661 			    dev->page == dev->orig_page &&
3662 			    !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {
3663 				/* alloc page for prexor */
3664 				struct page *p = alloc_page(GFP_NOIO);
3665 
3666 				if (p) {
3667 					dev->orig_page = p;
3668 					continue;
3669 				}
3670 
3671 				/*
3672 				 * alloc_page() failed, try use
3673 				 * disk_info->extra_page
3674 				 */
3675 				if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,
3676 						      &conf->cache_state)) {
3677 					r5c_use_extra_page(sh);
3678 					break;
3679 				}
3680 
3681 				/* extra_page in use, add to delayed_list */
3682 				set_bit(STRIPE_DELAYED, &sh->state);
3683 				s->waiting_extra_page = 1;
3684 				return -EAGAIN;
3685 			}
3686 		}
3687 
3688 		for (i = disks; i--; ) {
3689 			struct r5dev *dev = &sh->dev[i];
3690 			if ((dev->towrite ||
3691 			     i == sh->pd_idx || i == sh->qd_idx ||
3692 			     test_bit(R5_InJournal, &dev->flags)) &&
3693 			    !test_bit(R5_LOCKED, &dev->flags) &&
3694 			    !((test_bit(R5_UPTODATE, &dev->flags) &&
3695 			       (!test_bit(R5_InJournal, &dev->flags) ||
3696 				dev->page != dev->orig_page)) ||
3697 			      test_bit(R5_Wantcompute, &dev->flags)) &&
3698 			    test_bit(R5_Insync, &dev->flags)) {
3699 				if (test_bit(STRIPE_PREREAD_ACTIVE,
3700 					     &sh->state)) {
3701 					pr_debug("Read_old block %d for r-m-w\n",
3702 						 i);
3703 					set_bit(R5_LOCKED, &dev->flags);
3704 					set_bit(R5_Wantread, &dev->flags);
3705 					s->locked++;
3706 				} else {
3707 					set_bit(STRIPE_DELAYED, &sh->state);
3708 					set_bit(STRIPE_HANDLE, &sh->state);
3709 				}
3710 			}
3711 		}
3712 	}
3713 	if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
3714 		/* want reconstruct write, but need to get some data */
3715 		int qread =0;
3716 		rcw = 0;
3717 		for (i = disks; i--; ) {
3718 			struct r5dev *dev = &sh->dev[i];
3719 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3720 			    i != sh->pd_idx && i != sh->qd_idx &&
3721 			    !test_bit(R5_LOCKED, &dev->flags) &&
3722 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
3723 			      test_bit(R5_InJournal, &dev->flags) ||
3724 			      test_bit(R5_Wantcompute, &dev->flags))) {
3725 				rcw++;
3726 				if (test_bit(R5_Insync, &dev->flags) &&
3727 				    test_bit(STRIPE_PREREAD_ACTIVE,
3728 					     &sh->state)) {
3729 					pr_debug("Read_old block "
3730 						"%d for Reconstruct\n", i);
3731 					set_bit(R5_LOCKED, &dev->flags);
3732 					set_bit(R5_Wantread, &dev->flags);
3733 					s->locked++;
3734 					qread++;
3735 				} else {
3736 					set_bit(STRIPE_DELAYED, &sh->state);
3737 					set_bit(STRIPE_HANDLE, &sh->state);
3738 				}
3739 			}
3740 		}
3741 		if (rcw && conf->mddev->queue)
3742 			blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3743 					  (unsigned long long)sh->sector,
3744 					  rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3745 	}
3746 
3747 	if (rcw > disks && rmw > disks &&
3748 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3749 		set_bit(STRIPE_DELAYED, &sh->state);
3750 
3751 	/* now if nothing is locked, and if we have enough data,
3752 	 * we can start a write request
3753 	 */
3754 	/* since handle_stripe can be called at any time we need to handle the
3755 	 * case where a compute block operation has been submitted and then a
3756 	 * subsequent call wants to start a write request.  raid_run_ops only
3757 	 * handles the case where compute block and reconstruct are requested
3758 	 * simultaneously.  If this is not the case then new writes need to be
3759 	 * held off until the compute completes.
3760 	 */
3761 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3762 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3763 	     !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3764 		schedule_reconstruction(sh, s, rcw == 0, 0);
3765 	return 0;
3766 }
3767 
3768 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3769 				struct stripe_head_state *s, int disks)
3770 {
3771 	struct r5dev *dev = NULL;
3772 
3773 	BUG_ON(sh->batch_head);
3774 	set_bit(STRIPE_HANDLE, &sh->state);
3775 
3776 	switch (sh->check_state) {
3777 	case check_state_idle:
3778 		/* start a new check operation if there are no failures */
3779 		if (s->failed == 0) {
3780 			BUG_ON(s->uptodate != disks);
3781 			sh->check_state = check_state_run;
3782 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3783 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3784 			s->uptodate--;
3785 			break;
3786 		}
3787 		dev = &sh->dev[s->failed_num[0]];
3788 		/* fall through */
3789 	case check_state_compute_result:
3790 		sh->check_state = check_state_idle;
3791 		if (!dev)
3792 			dev = &sh->dev[sh->pd_idx];
3793 
3794 		/* check that a write has not made the stripe insync */
3795 		if (test_bit(STRIPE_INSYNC, &sh->state))
3796 			break;
3797 
3798 		/* either failed parity check, or recovery is happening */
3799 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3800 		BUG_ON(s->uptodate != disks);
3801 
3802 		set_bit(R5_LOCKED, &dev->flags);
3803 		s->locked++;
3804 		set_bit(R5_Wantwrite, &dev->flags);
3805 
3806 		clear_bit(STRIPE_DEGRADED, &sh->state);
3807 		set_bit(STRIPE_INSYNC, &sh->state);
3808 		break;
3809 	case check_state_run:
3810 		break; /* we will be called again upon completion */
3811 	case check_state_check_result:
3812 		sh->check_state = check_state_idle;
3813 
3814 		/* if a failure occurred during the check operation, leave
3815 		 * STRIPE_INSYNC not set and let the stripe be handled again
3816 		 */
3817 		if (s->failed)
3818 			break;
3819 
3820 		/* handle a successful check operation, if parity is correct
3821 		 * we are done.  Otherwise update the mismatch count and repair
3822 		 * parity if !MD_RECOVERY_CHECK
3823 		 */
3824 		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3825 			/* parity is correct (on disc,
3826 			 * not in buffer any more)
3827 			 */
3828 			set_bit(STRIPE_INSYNC, &sh->state);
3829 		else {
3830 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3831 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3832 				/* don't try to repair!! */
3833 				set_bit(STRIPE_INSYNC, &sh->state);
3834 			else {
3835 				sh->check_state = check_state_compute_run;
3836 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3837 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3838 				set_bit(R5_Wantcompute,
3839 					&sh->dev[sh->pd_idx].flags);
3840 				sh->ops.target = sh->pd_idx;
3841 				sh->ops.target2 = -1;
3842 				s->uptodate++;
3843 			}
3844 		}
3845 		break;
3846 	case check_state_compute_run:
3847 		break;
3848 	default:
3849 		pr_err("%s: unknown check_state: %d sector: %llu\n",
3850 		       __func__, sh->check_state,
3851 		       (unsigned long long) sh->sector);
3852 		BUG();
3853 	}
3854 }
3855 
3856 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3857 				  struct stripe_head_state *s,
3858 				  int disks)
3859 {
3860 	int pd_idx = sh->pd_idx;
3861 	int qd_idx = sh->qd_idx;
3862 	struct r5dev *dev;
3863 
3864 	BUG_ON(sh->batch_head);
3865 	set_bit(STRIPE_HANDLE, &sh->state);
3866 
3867 	BUG_ON(s->failed > 2);
3868 
3869 	/* Want to check and possibly repair P and Q.
3870 	 * However there could be one 'failed' device, in which
3871 	 * case we can only check one of them, possibly using the
3872 	 * other to generate missing data
3873 	 */
3874 
3875 	switch (sh->check_state) {
3876 	case check_state_idle:
3877 		/* start a new check operation if there are < 2 failures */
3878 		if (s->failed == s->q_failed) {
3879 			/* The only possible failed device holds Q, so it
3880 			 * makes sense to check P (If anything else were failed,
3881 			 * we would have used P to recreate it).
3882 			 */
3883 			sh->check_state = check_state_run;
3884 		}
3885 		if (!s->q_failed && s->failed < 2) {
3886 			/* Q is not failed, and we didn't use it to generate
3887 			 * anything, so it makes sense to check it
3888 			 */
3889 			if (sh->check_state == check_state_run)
3890 				sh->check_state = check_state_run_pq;
3891 			else
3892 				sh->check_state = check_state_run_q;
3893 		}
3894 
3895 		/* discard potentially stale zero_sum_result */
3896 		sh->ops.zero_sum_result = 0;
3897 
3898 		if (sh->check_state == check_state_run) {
3899 			/* async_xor_zero_sum destroys the contents of P */
3900 			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3901 			s->uptodate--;
3902 		}
3903 		if (sh->check_state >= check_state_run &&
3904 		    sh->check_state <= check_state_run_pq) {
3905 			/* async_syndrome_zero_sum preserves P and Q, so
3906 			 * no need to mark them !uptodate here
3907 			 */
3908 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3909 			break;
3910 		}
3911 
3912 		/* we have 2-disk failure */
3913 		BUG_ON(s->failed != 2);
3914 		/* fall through */
3915 	case check_state_compute_result:
3916 		sh->check_state = check_state_idle;
3917 
3918 		/* check that a write has not made the stripe insync */
3919 		if (test_bit(STRIPE_INSYNC, &sh->state))
3920 			break;
3921 
3922 		/* now write out any block on a failed drive,
3923 		 * or P or Q if they were recomputed
3924 		 */
3925 		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3926 		if (s->failed == 2) {
3927 			dev = &sh->dev[s->failed_num[1]];
3928 			s->locked++;
3929 			set_bit(R5_LOCKED, &dev->flags);
3930 			set_bit(R5_Wantwrite, &dev->flags);
3931 		}
3932 		if (s->failed >= 1) {
3933 			dev = &sh->dev[s->failed_num[0]];
3934 			s->locked++;
3935 			set_bit(R5_LOCKED, &dev->flags);
3936 			set_bit(R5_Wantwrite, &dev->flags);
3937 		}
3938 		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3939 			dev = &sh->dev[pd_idx];
3940 			s->locked++;
3941 			set_bit(R5_LOCKED, &dev->flags);
3942 			set_bit(R5_Wantwrite, &dev->flags);
3943 		}
3944 		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3945 			dev = &sh->dev[qd_idx];
3946 			s->locked++;
3947 			set_bit(R5_LOCKED, &dev->flags);
3948 			set_bit(R5_Wantwrite, &dev->flags);
3949 		}
3950 		clear_bit(STRIPE_DEGRADED, &sh->state);
3951 
3952 		set_bit(STRIPE_INSYNC, &sh->state);
3953 		break;
3954 	case check_state_run:
3955 	case check_state_run_q:
3956 	case check_state_run_pq:
3957 		break; /* we will be called again upon completion */
3958 	case check_state_check_result:
3959 		sh->check_state = check_state_idle;
3960 
3961 		/* handle a successful check operation, if parity is correct
3962 		 * we are done.  Otherwise update the mismatch count and repair
3963 		 * parity if !MD_RECOVERY_CHECK
3964 		 */
3965 		if (sh->ops.zero_sum_result == 0) {
3966 			/* both parities are correct */
3967 			if (!s->failed)
3968 				set_bit(STRIPE_INSYNC, &sh->state);
3969 			else {
3970 				/* in contrast to the raid5 case we can validate
3971 				 * parity, but still have a failure to write
3972 				 * back
3973 				 */
3974 				sh->check_state = check_state_compute_result;
3975 				/* Returning at this point means that we may go
3976 				 * off and bring p and/or q uptodate again so
3977 				 * we make sure to check zero_sum_result again
3978 				 * to verify if p or q need writeback
3979 				 */
3980 			}
3981 		} else {
3982 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3983 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3984 				/* don't try to repair!! */
3985 				set_bit(STRIPE_INSYNC, &sh->state);
3986 			else {
3987 				int *target = &sh->ops.target;
3988 
3989 				sh->ops.target = -1;
3990 				sh->ops.target2 = -1;
3991 				sh->check_state = check_state_compute_run;
3992 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3993 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3994 				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3995 					set_bit(R5_Wantcompute,
3996 						&sh->dev[pd_idx].flags);
3997 					*target = pd_idx;
3998 					target = &sh->ops.target2;
3999 					s->uptodate++;
4000 				}
4001 				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4002 					set_bit(R5_Wantcompute,
4003 						&sh->dev[qd_idx].flags);
4004 					*target = qd_idx;
4005 					s->uptodate++;
4006 				}
4007 			}
4008 		}
4009 		break;
4010 	case check_state_compute_run:
4011 		break;
4012 	default:
4013 		pr_warn("%s: unknown check_state: %d sector: %llu\n",
4014 			__func__, sh->check_state,
4015 			(unsigned long long) sh->sector);
4016 		BUG();
4017 	}
4018 }
4019 
4020 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
4021 {
4022 	int i;
4023 
4024 	/* We have read all the blocks in this stripe and now we need to
4025 	 * copy some of them into a target stripe for expand.
4026 	 */
4027 	struct dma_async_tx_descriptor *tx = NULL;
4028 	BUG_ON(sh->batch_head);
4029 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4030 	for (i = 0; i < sh->disks; i++)
4031 		if (i != sh->pd_idx && i != sh->qd_idx) {
4032 			int dd_idx, j;
4033 			struct stripe_head *sh2;
4034 			struct async_submit_ctl submit;
4035 
4036 			sector_t bn = raid5_compute_blocknr(sh, i, 1);
4037 			sector_t s = raid5_compute_sector(conf, bn, 0,
4038 							  &dd_idx, NULL);
4039 			sh2 = raid5_get_active_stripe(conf, s, 0, 1, 1);
4040 			if (sh2 == NULL)
4041 				/* so far only the early blocks of this stripe
4042 				 * have been requested.  When later blocks
4043 				 * get requested, we will try again
4044 				 */
4045 				continue;
4046 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
4047 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
4048 				/* must have already done this block */
4049 				raid5_release_stripe(sh2);
4050 				continue;
4051 			}
4052 
4053 			/* place all the copies on one channel */
4054 			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4055 			tx = async_memcpy(sh2->dev[dd_idx].page,
4056 					  sh->dev[i].page, 0, 0, STRIPE_SIZE,
4057 					  &submit);
4058 
4059 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4060 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4061 			for (j = 0; j < conf->raid_disks; j++)
4062 				if (j != sh2->pd_idx &&
4063 				    j != sh2->qd_idx &&
4064 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
4065 					break;
4066 			if (j == conf->raid_disks) {
4067 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
4068 				set_bit(STRIPE_HANDLE, &sh2->state);
4069 			}
4070 			raid5_release_stripe(sh2);
4071 
4072 		}
4073 	/* done submitting copies, wait for them to complete */
4074 	async_tx_quiesce(&tx);
4075 }
4076 
4077 /*
4078  * handle_stripe - do things to a stripe.
4079  *
4080  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4081  * state of various bits to see what needs to be done.
4082  * Possible results:
4083  *    return some read requests which now have data
4084  *    return some write requests which are safely on storage
4085  *    schedule a read on some buffers
4086  *    schedule a write of some buffers
4087  *    return confirmation of parity correctness
4088  *
4089  */
4090 
4091 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4092 {
4093 	struct r5conf *conf = sh->raid_conf;
4094 	int disks = sh->disks;
4095 	struct r5dev *dev;
4096 	int i;
4097 	int do_recovery = 0;
4098 
4099 	memset(s, 0, sizeof(*s));
4100 
4101 	s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4102 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4103 	s->failed_num[0] = -1;
4104 	s->failed_num[1] = -1;
4105 	s->log_failed = r5l_log_disk_error(conf);
4106 
4107 	/* Now to look around and see what can be done */
4108 	rcu_read_lock();
4109 	for (i=disks; i--; ) {
4110 		struct md_rdev *rdev;
4111 		sector_t first_bad;
4112 		int bad_sectors;
4113 		int is_bad = 0;
4114 
4115 		dev = &sh->dev[i];
4116 
4117 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4118 			 i, dev->flags,
4119 			 dev->toread, dev->towrite, dev->written);
4120 		/* maybe we can reply to a read
4121 		 *
4122 		 * new wantfill requests are only permitted while
4123 		 * ops_complete_biofill is guaranteed to be inactive
4124 		 */
4125 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4126 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4127 			set_bit(R5_Wantfill, &dev->flags);
4128 
4129 		/* now count some things */
4130 		if (test_bit(R5_LOCKED, &dev->flags))
4131 			s->locked++;
4132 		if (test_bit(R5_UPTODATE, &dev->flags))
4133 			s->uptodate++;
4134 		if (test_bit(R5_Wantcompute, &dev->flags)) {
4135 			s->compute++;
4136 			BUG_ON(s->compute > 2);
4137 		}
4138 
4139 		if (test_bit(R5_Wantfill, &dev->flags))
4140 			s->to_fill++;
4141 		else if (dev->toread)
4142 			s->to_read++;
4143 		if (dev->towrite) {
4144 			s->to_write++;
4145 			if (!test_bit(R5_OVERWRITE, &dev->flags))
4146 				s->non_overwrite++;
4147 		}
4148 		if (dev->written)
4149 			s->written++;
4150 		/* Prefer to use the replacement for reads, but only
4151 		 * if it is recovered enough and has no bad blocks.
4152 		 */
4153 		rdev = rcu_dereference(conf->disks[i].replacement);
4154 		if (rdev && !test_bit(Faulty, &rdev->flags) &&
4155 		    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4156 		    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4157 				 &first_bad, &bad_sectors))
4158 			set_bit(R5_ReadRepl, &dev->flags);
4159 		else {
4160 			if (rdev && !test_bit(Faulty, &rdev->flags))
4161 				set_bit(R5_NeedReplace, &dev->flags);
4162 			else
4163 				clear_bit(R5_NeedReplace, &dev->flags);
4164 			rdev = rcu_dereference(conf->disks[i].rdev);
4165 			clear_bit(R5_ReadRepl, &dev->flags);
4166 		}
4167 		if (rdev && test_bit(Faulty, &rdev->flags))
4168 			rdev = NULL;
4169 		if (rdev) {
4170 			is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4171 					     &first_bad, &bad_sectors);
4172 			if (s->blocked_rdev == NULL
4173 			    && (test_bit(Blocked, &rdev->flags)
4174 				|| is_bad < 0)) {
4175 				if (is_bad < 0)
4176 					set_bit(BlockedBadBlocks,
4177 						&rdev->flags);
4178 				s->blocked_rdev = rdev;
4179 				atomic_inc(&rdev->nr_pending);
4180 			}
4181 		}
4182 		clear_bit(R5_Insync, &dev->flags);
4183 		if (!rdev)
4184 			/* Not in-sync */;
4185 		else if (is_bad) {
4186 			/* also not in-sync */
4187 			if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4188 			    test_bit(R5_UPTODATE, &dev->flags)) {
4189 				/* treat as in-sync, but with a read error
4190 				 * which we can now try to correct
4191 				 */
4192 				set_bit(R5_Insync, &dev->flags);
4193 				set_bit(R5_ReadError, &dev->flags);
4194 			}
4195 		} else if (test_bit(In_sync, &rdev->flags))
4196 			set_bit(R5_Insync, &dev->flags);
4197 		else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4198 			/* in sync if before recovery_offset */
4199 			set_bit(R5_Insync, &dev->flags);
4200 		else if (test_bit(R5_UPTODATE, &dev->flags) &&
4201 			 test_bit(R5_Expanded, &dev->flags))
4202 			/* If we've reshaped into here, we assume it is Insync.
4203 			 * We will shortly update recovery_offset to make
4204 			 * it official.
4205 			 */
4206 			set_bit(R5_Insync, &dev->flags);
4207 
4208 		if (test_bit(R5_WriteError, &dev->flags)) {
4209 			/* This flag does not apply to '.replacement'
4210 			 * only to .rdev, so make sure to check that*/
4211 			struct md_rdev *rdev2 = rcu_dereference(
4212 				conf->disks[i].rdev);
4213 			if (rdev2 == rdev)
4214 				clear_bit(R5_Insync, &dev->flags);
4215 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4216 				s->handle_bad_blocks = 1;
4217 				atomic_inc(&rdev2->nr_pending);
4218 			} else
4219 				clear_bit(R5_WriteError, &dev->flags);
4220 		}
4221 		if (test_bit(R5_MadeGood, &dev->flags)) {
4222 			/* This flag does not apply to '.replacement'
4223 			 * only to .rdev, so make sure to check that*/
4224 			struct md_rdev *rdev2 = rcu_dereference(
4225 				conf->disks[i].rdev);
4226 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4227 				s->handle_bad_blocks = 1;
4228 				atomic_inc(&rdev2->nr_pending);
4229 			} else
4230 				clear_bit(R5_MadeGood, &dev->flags);
4231 		}
4232 		if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4233 			struct md_rdev *rdev2 = rcu_dereference(
4234 				conf->disks[i].replacement);
4235 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4236 				s->handle_bad_blocks = 1;
4237 				atomic_inc(&rdev2->nr_pending);
4238 			} else
4239 				clear_bit(R5_MadeGoodRepl, &dev->flags);
4240 		}
4241 		if (!test_bit(R5_Insync, &dev->flags)) {
4242 			/* The ReadError flag will just be confusing now */
4243 			clear_bit(R5_ReadError, &dev->flags);
4244 			clear_bit(R5_ReWrite, &dev->flags);
4245 		}
4246 		if (test_bit(R5_ReadError, &dev->flags))
4247 			clear_bit(R5_Insync, &dev->flags);
4248 		if (!test_bit(R5_Insync, &dev->flags)) {
4249 			if (s->failed < 2)
4250 				s->failed_num[s->failed] = i;
4251 			s->failed++;
4252 			if (rdev && !test_bit(Faulty, &rdev->flags))
4253 				do_recovery = 1;
4254 		}
4255 
4256 		if (test_bit(R5_InJournal, &dev->flags))
4257 			s->injournal++;
4258 		if (test_bit(R5_InJournal, &dev->flags) && dev->written)
4259 			s->just_cached++;
4260 	}
4261 	if (test_bit(STRIPE_SYNCING, &sh->state)) {
4262 		/* If there is a failed device being replaced,
4263 		 *     we must be recovering.
4264 		 * else if we are after recovery_cp, we must be syncing
4265 		 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4266 		 * else we can only be replacing
4267 		 * sync and recovery both need to read all devices, and so
4268 		 * use the same flag.
4269 		 */
4270 		if (do_recovery ||
4271 		    sh->sector >= conf->mddev->recovery_cp ||
4272 		    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4273 			s->syncing = 1;
4274 		else
4275 			s->replacing = 1;
4276 	}
4277 	rcu_read_unlock();
4278 }
4279 
4280 static int clear_batch_ready(struct stripe_head *sh)
4281 {
4282 	/* Return '1' if this is a member of batch, or
4283 	 * '0' if it is a lone stripe or a head which can now be
4284 	 * handled.
4285 	 */
4286 	struct stripe_head *tmp;
4287 	if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4288 		return (sh->batch_head && sh->batch_head != sh);
4289 	spin_lock(&sh->stripe_lock);
4290 	if (!sh->batch_head) {
4291 		spin_unlock(&sh->stripe_lock);
4292 		return 0;
4293 	}
4294 
4295 	/*
4296 	 * this stripe could be added to a batch list before we check
4297 	 * BATCH_READY, skips it
4298 	 */
4299 	if (sh->batch_head != sh) {
4300 		spin_unlock(&sh->stripe_lock);
4301 		return 1;
4302 	}
4303 	spin_lock(&sh->batch_lock);
4304 	list_for_each_entry(tmp, &sh->batch_list, batch_list)
4305 		clear_bit(STRIPE_BATCH_READY, &tmp->state);
4306 	spin_unlock(&sh->batch_lock);
4307 	spin_unlock(&sh->stripe_lock);
4308 
4309 	/*
4310 	 * BATCH_READY is cleared, no new stripes can be added.
4311 	 * batch_list can be accessed without lock
4312 	 */
4313 	return 0;
4314 }
4315 
4316 static void break_stripe_batch_list(struct stripe_head *head_sh,
4317 				    unsigned long handle_flags)
4318 {
4319 	struct stripe_head *sh, *next;
4320 	int i;
4321 	int do_wakeup = 0;
4322 
4323 	list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4324 
4325 		list_del_init(&sh->batch_list);
4326 
4327 		WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4328 					  (1 << STRIPE_SYNCING) |
4329 					  (1 << STRIPE_REPLACED) |
4330 					  (1 << STRIPE_DELAYED) |
4331 					  (1 << STRIPE_BIT_DELAY) |
4332 					  (1 << STRIPE_FULL_WRITE) |
4333 					  (1 << STRIPE_BIOFILL_RUN) |
4334 					  (1 << STRIPE_COMPUTE_RUN)  |
4335 					  (1 << STRIPE_OPS_REQ_PENDING) |
4336 					  (1 << STRIPE_DISCARD) |
4337 					  (1 << STRIPE_BATCH_READY) |
4338 					  (1 << STRIPE_BATCH_ERR) |
4339 					  (1 << STRIPE_BITMAP_PENDING)),
4340 			"stripe state: %lx\n", sh->state);
4341 		WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4342 					      (1 << STRIPE_REPLACED)),
4343 			"head stripe state: %lx\n", head_sh->state);
4344 
4345 		set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4346 					    (1 << STRIPE_PREREAD_ACTIVE) |
4347 					    (1 << STRIPE_DEGRADED)),
4348 			      head_sh->state & (1 << STRIPE_INSYNC));
4349 
4350 		sh->check_state = head_sh->check_state;
4351 		sh->reconstruct_state = head_sh->reconstruct_state;
4352 		for (i = 0; i < sh->disks; i++) {
4353 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4354 				do_wakeup = 1;
4355 			sh->dev[i].flags = head_sh->dev[i].flags &
4356 				(~((1 << R5_WriteError) | (1 << R5_Overlap)));
4357 		}
4358 		spin_lock_irq(&sh->stripe_lock);
4359 		sh->batch_head = NULL;
4360 		spin_unlock_irq(&sh->stripe_lock);
4361 		if (handle_flags == 0 ||
4362 		    sh->state & handle_flags)
4363 			set_bit(STRIPE_HANDLE, &sh->state);
4364 		raid5_release_stripe(sh);
4365 	}
4366 	spin_lock_irq(&head_sh->stripe_lock);
4367 	head_sh->batch_head = NULL;
4368 	spin_unlock_irq(&head_sh->stripe_lock);
4369 	for (i = 0; i < head_sh->disks; i++)
4370 		if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4371 			do_wakeup = 1;
4372 	if (head_sh->state & handle_flags)
4373 		set_bit(STRIPE_HANDLE, &head_sh->state);
4374 
4375 	if (do_wakeup)
4376 		wake_up(&head_sh->raid_conf->wait_for_overlap);
4377 }
4378 
4379 static void handle_stripe(struct stripe_head *sh)
4380 {
4381 	struct stripe_head_state s;
4382 	struct r5conf *conf = sh->raid_conf;
4383 	int i;
4384 	int prexor;
4385 	int disks = sh->disks;
4386 	struct r5dev *pdev, *qdev;
4387 
4388 	clear_bit(STRIPE_HANDLE, &sh->state);
4389 	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4390 		/* already being handled, ensure it gets handled
4391 		 * again when current action finishes */
4392 		set_bit(STRIPE_HANDLE, &sh->state);
4393 		return;
4394 	}
4395 
4396 	if (clear_batch_ready(sh) ) {
4397 		clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4398 		return;
4399 	}
4400 
4401 	if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4402 		break_stripe_batch_list(sh, 0);
4403 
4404 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4405 		spin_lock(&sh->stripe_lock);
4406 		/* Cannot process 'sync' concurrently with 'discard' */
4407 		if (!test_bit(STRIPE_DISCARD, &sh->state) &&
4408 		    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4409 			set_bit(STRIPE_SYNCING, &sh->state);
4410 			clear_bit(STRIPE_INSYNC, &sh->state);
4411 			clear_bit(STRIPE_REPLACED, &sh->state);
4412 		}
4413 		spin_unlock(&sh->stripe_lock);
4414 	}
4415 	clear_bit(STRIPE_DELAYED, &sh->state);
4416 
4417 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4418 		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4419 	       (unsigned long long)sh->sector, sh->state,
4420 	       atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4421 	       sh->check_state, sh->reconstruct_state);
4422 
4423 	analyse_stripe(sh, &s);
4424 
4425 	if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
4426 		goto finish;
4427 
4428 	if (s.handle_bad_blocks) {
4429 		set_bit(STRIPE_HANDLE, &sh->state);
4430 		goto finish;
4431 	}
4432 
4433 	if (unlikely(s.blocked_rdev)) {
4434 		if (s.syncing || s.expanding || s.expanded ||
4435 		    s.replacing || s.to_write || s.written) {
4436 			set_bit(STRIPE_HANDLE, &sh->state);
4437 			goto finish;
4438 		}
4439 		/* There is nothing for the blocked_rdev to block */
4440 		rdev_dec_pending(s.blocked_rdev, conf->mddev);
4441 		s.blocked_rdev = NULL;
4442 	}
4443 
4444 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4445 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4446 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4447 	}
4448 
4449 	pr_debug("locked=%d uptodate=%d to_read=%d"
4450 	       " to_write=%d failed=%d failed_num=%d,%d\n",
4451 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4452 	       s.failed_num[0], s.failed_num[1]);
4453 	/* check if the array has lost more than max_degraded devices and,
4454 	 * if so, some requests might need to be failed.
4455 	 */
4456 	if (s.failed > conf->max_degraded || s.log_failed) {
4457 		sh->check_state = 0;
4458 		sh->reconstruct_state = 0;
4459 		break_stripe_batch_list(sh, 0);
4460 		if (s.to_read+s.to_write+s.written)
4461 			handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
4462 		if (s.syncing + s.replacing)
4463 			handle_failed_sync(conf, sh, &s);
4464 	}
4465 
4466 	/* Now we check to see if any write operations have recently
4467 	 * completed
4468 	 */
4469 	prexor = 0;
4470 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4471 		prexor = 1;
4472 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
4473 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4474 		sh->reconstruct_state = reconstruct_state_idle;
4475 
4476 		/* All the 'written' buffers and the parity block are ready to
4477 		 * be written back to disk
4478 		 */
4479 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4480 		       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4481 		BUG_ON(sh->qd_idx >= 0 &&
4482 		       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4483 		       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4484 		for (i = disks; i--; ) {
4485 			struct r5dev *dev = &sh->dev[i];
4486 			if (test_bit(R5_LOCKED, &dev->flags) &&
4487 				(i == sh->pd_idx || i == sh->qd_idx ||
4488 				 dev->written || test_bit(R5_InJournal,
4489 							  &dev->flags))) {
4490 				pr_debug("Writing block %d\n", i);
4491 				set_bit(R5_Wantwrite, &dev->flags);
4492 				if (prexor)
4493 					continue;
4494 				if (s.failed > 1)
4495 					continue;
4496 				if (!test_bit(R5_Insync, &dev->flags) ||
4497 				    ((i == sh->pd_idx || i == sh->qd_idx)  &&
4498 				     s.failed == 0))
4499 					set_bit(STRIPE_INSYNC, &sh->state);
4500 			}
4501 		}
4502 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4503 			s.dec_preread_active = 1;
4504 	}
4505 
4506 	/*
4507 	 * might be able to return some write requests if the parity blocks
4508 	 * are safe, or on a failed drive
4509 	 */
4510 	pdev = &sh->dev[sh->pd_idx];
4511 	s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4512 		|| (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4513 	qdev = &sh->dev[sh->qd_idx];
4514 	s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4515 		|| (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4516 		|| conf->level < 6;
4517 
4518 	if (s.written &&
4519 	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4520 			     && !test_bit(R5_LOCKED, &pdev->flags)
4521 			     && (test_bit(R5_UPTODATE, &pdev->flags) ||
4522 				 test_bit(R5_Discard, &pdev->flags))))) &&
4523 	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4524 			     && !test_bit(R5_LOCKED, &qdev->flags)
4525 			     && (test_bit(R5_UPTODATE, &qdev->flags) ||
4526 				 test_bit(R5_Discard, &qdev->flags))))))
4527 		handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
4528 
4529 	if (s.just_cached)
4530 		r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
4531 	r5l_stripe_write_finished(sh);
4532 
4533 	/* Now we might consider reading some blocks, either to check/generate
4534 	 * parity, or to satisfy requests
4535 	 * or to load a block that is being partially written.
4536 	 */
4537 	if (s.to_read || s.non_overwrite
4538 	    || (conf->level == 6 && s.to_write && s.failed)
4539 	    || (s.syncing && (s.uptodate + s.compute < disks))
4540 	    || s.replacing
4541 	    || s.expanding)
4542 		handle_stripe_fill(sh, &s, disks);
4543 
4544 	/*
4545 	 * When the stripe finishes full journal write cycle (write to journal
4546 	 * and raid disk), this is the clean up procedure so it is ready for
4547 	 * next operation.
4548 	 */
4549 	r5c_finish_stripe_write_out(conf, sh, &s);
4550 
4551 	/*
4552 	 * Now to consider new write requests, cache write back and what else,
4553 	 * if anything should be read.  We do not handle new writes when:
4554 	 * 1/ A 'write' operation (copy+xor) is already in flight.
4555 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
4556 	 *    block.
4557 	 * 3/ A r5c cache log write is in flight.
4558 	 */
4559 
4560 	if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
4561 		if (!r5c_is_writeback(conf->log)) {
4562 			if (s.to_write)
4563 				handle_stripe_dirtying(conf, sh, &s, disks);
4564 		} else { /* write back cache */
4565 			int ret = 0;
4566 
4567 			/* First, try handle writes in caching phase */
4568 			if (s.to_write)
4569 				ret = r5c_try_caching_write(conf, sh, &s,
4570 							    disks);
4571 			/*
4572 			 * If caching phase failed: ret == -EAGAIN
4573 			 *    OR
4574 			 * stripe under reclaim: !caching && injournal
4575 			 *
4576 			 * fall back to handle_stripe_dirtying()
4577 			 */
4578 			if (ret == -EAGAIN ||
4579 			    /* stripe under reclaim: !caching && injournal */
4580 			    (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
4581 			     s.injournal > 0)) {
4582 				ret = handle_stripe_dirtying(conf, sh, &s,
4583 							     disks);
4584 				if (ret == -EAGAIN)
4585 					goto finish;
4586 			}
4587 		}
4588 	}
4589 
4590 	/* maybe we need to check and possibly fix the parity for this stripe
4591 	 * Any reads will already have been scheduled, so we just see if enough
4592 	 * data is available.  The parity check is held off while parity
4593 	 * dependent operations are in flight.
4594 	 */
4595 	if (sh->check_state ||
4596 	    (s.syncing && s.locked == 0 &&
4597 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4598 	     !test_bit(STRIPE_INSYNC, &sh->state))) {
4599 		if (conf->level == 6)
4600 			handle_parity_checks6(conf, sh, &s, disks);
4601 		else
4602 			handle_parity_checks5(conf, sh, &s, disks);
4603 	}
4604 
4605 	if ((s.replacing || s.syncing) && s.locked == 0
4606 	    && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4607 	    && !test_bit(STRIPE_REPLACED, &sh->state)) {
4608 		/* Write out to replacement devices where possible */
4609 		for (i = 0; i < conf->raid_disks; i++)
4610 			if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4611 				WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4612 				set_bit(R5_WantReplace, &sh->dev[i].flags);
4613 				set_bit(R5_LOCKED, &sh->dev[i].flags);
4614 				s.locked++;
4615 			}
4616 		if (s.replacing)
4617 			set_bit(STRIPE_INSYNC, &sh->state);
4618 		set_bit(STRIPE_REPLACED, &sh->state);
4619 	}
4620 	if ((s.syncing || s.replacing) && s.locked == 0 &&
4621 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4622 	    test_bit(STRIPE_INSYNC, &sh->state)) {
4623 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4624 		clear_bit(STRIPE_SYNCING, &sh->state);
4625 		if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4626 			wake_up(&conf->wait_for_overlap);
4627 	}
4628 
4629 	/* If the failed drives are just a ReadError, then we might need
4630 	 * to progress the repair/check process
4631 	 */
4632 	if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4633 		for (i = 0; i < s.failed; i++) {
4634 			struct r5dev *dev = &sh->dev[s.failed_num[i]];
4635 			if (test_bit(R5_ReadError, &dev->flags)
4636 			    && !test_bit(R5_LOCKED, &dev->flags)
4637 			    && test_bit(R5_UPTODATE, &dev->flags)
4638 				) {
4639 				if (!test_bit(R5_ReWrite, &dev->flags)) {
4640 					set_bit(R5_Wantwrite, &dev->flags);
4641 					set_bit(R5_ReWrite, &dev->flags);
4642 					set_bit(R5_LOCKED, &dev->flags);
4643 					s.locked++;
4644 				} else {
4645 					/* let's read it back */
4646 					set_bit(R5_Wantread, &dev->flags);
4647 					set_bit(R5_LOCKED, &dev->flags);
4648 					s.locked++;
4649 				}
4650 			}
4651 		}
4652 
4653 	/* Finish reconstruct operations initiated by the expansion process */
4654 	if (sh->reconstruct_state == reconstruct_state_result) {
4655 		struct stripe_head *sh_src
4656 			= raid5_get_active_stripe(conf, sh->sector, 1, 1, 1);
4657 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4658 			/* sh cannot be written until sh_src has been read.
4659 			 * so arrange for sh to be delayed a little
4660 			 */
4661 			set_bit(STRIPE_DELAYED, &sh->state);
4662 			set_bit(STRIPE_HANDLE, &sh->state);
4663 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4664 					      &sh_src->state))
4665 				atomic_inc(&conf->preread_active_stripes);
4666 			raid5_release_stripe(sh_src);
4667 			goto finish;
4668 		}
4669 		if (sh_src)
4670 			raid5_release_stripe(sh_src);
4671 
4672 		sh->reconstruct_state = reconstruct_state_idle;
4673 		clear_bit(STRIPE_EXPANDING, &sh->state);
4674 		for (i = conf->raid_disks; i--; ) {
4675 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
4676 			set_bit(R5_LOCKED, &sh->dev[i].flags);
4677 			s.locked++;
4678 		}
4679 	}
4680 
4681 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4682 	    !sh->reconstruct_state) {
4683 		/* Need to write out all blocks after computing parity */
4684 		sh->disks = conf->raid_disks;
4685 		stripe_set_idx(sh->sector, conf, 0, sh);
4686 		schedule_reconstruction(sh, &s, 1, 1);
4687 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4688 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
4689 		atomic_dec(&conf->reshape_stripes);
4690 		wake_up(&conf->wait_for_overlap);
4691 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4692 	}
4693 
4694 	if (s.expanding && s.locked == 0 &&
4695 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4696 		handle_stripe_expansion(conf, sh);
4697 
4698 finish:
4699 	/* wait for this device to become unblocked */
4700 	if (unlikely(s.blocked_rdev)) {
4701 		if (conf->mddev->external)
4702 			md_wait_for_blocked_rdev(s.blocked_rdev,
4703 						 conf->mddev);
4704 		else
4705 			/* Internal metadata will immediately
4706 			 * be written by raid5d, so we don't
4707 			 * need to wait here.
4708 			 */
4709 			rdev_dec_pending(s.blocked_rdev,
4710 					 conf->mddev);
4711 	}
4712 
4713 	if (s.handle_bad_blocks)
4714 		for (i = disks; i--; ) {
4715 			struct md_rdev *rdev;
4716 			struct r5dev *dev = &sh->dev[i];
4717 			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4718 				/* We own a safe reference to the rdev */
4719 				rdev = conf->disks[i].rdev;
4720 				if (!rdev_set_badblocks(rdev, sh->sector,
4721 							STRIPE_SECTORS, 0))
4722 					md_error(conf->mddev, rdev);
4723 				rdev_dec_pending(rdev, conf->mddev);
4724 			}
4725 			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4726 				rdev = conf->disks[i].rdev;
4727 				rdev_clear_badblocks(rdev, sh->sector,
4728 						     STRIPE_SECTORS, 0);
4729 				rdev_dec_pending(rdev, conf->mddev);
4730 			}
4731 			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4732 				rdev = conf->disks[i].replacement;
4733 				if (!rdev)
4734 					/* rdev have been moved down */
4735 					rdev = conf->disks[i].rdev;
4736 				rdev_clear_badblocks(rdev, sh->sector,
4737 						     STRIPE_SECTORS, 0);
4738 				rdev_dec_pending(rdev, conf->mddev);
4739 			}
4740 		}
4741 
4742 	if (s.ops_request)
4743 		raid_run_ops(sh, s.ops_request);
4744 
4745 	ops_run_io(sh, &s);
4746 
4747 	if (s.dec_preread_active) {
4748 		/* We delay this until after ops_run_io so that if make_request
4749 		 * is waiting on a flush, it won't continue until the writes
4750 		 * have actually been submitted.
4751 		 */
4752 		atomic_dec(&conf->preread_active_stripes);
4753 		if (atomic_read(&conf->preread_active_stripes) <
4754 		    IO_THRESHOLD)
4755 			md_wakeup_thread(conf->mddev->thread);
4756 	}
4757 
4758 	if (!bio_list_empty(&s.return_bi)) {
4759 		if (test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) {
4760 			spin_lock_irq(&conf->device_lock);
4761 			bio_list_merge(&conf->return_bi, &s.return_bi);
4762 			spin_unlock_irq(&conf->device_lock);
4763 			md_wakeup_thread(conf->mddev->thread);
4764 		} else
4765 			return_io(&s.return_bi);
4766 	}
4767 
4768 	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4769 }
4770 
4771 static void raid5_activate_delayed(struct r5conf *conf)
4772 {
4773 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4774 		while (!list_empty(&conf->delayed_list)) {
4775 			struct list_head *l = conf->delayed_list.next;
4776 			struct stripe_head *sh;
4777 			sh = list_entry(l, struct stripe_head, lru);
4778 			list_del_init(l);
4779 			clear_bit(STRIPE_DELAYED, &sh->state);
4780 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4781 				atomic_inc(&conf->preread_active_stripes);
4782 			list_add_tail(&sh->lru, &conf->hold_list);
4783 			raid5_wakeup_stripe_thread(sh);
4784 		}
4785 	}
4786 }
4787 
4788 static void activate_bit_delay(struct r5conf *conf,
4789 	struct list_head *temp_inactive_list)
4790 {
4791 	/* device_lock is held */
4792 	struct list_head head;
4793 	list_add(&head, &conf->bitmap_list);
4794 	list_del_init(&conf->bitmap_list);
4795 	while (!list_empty(&head)) {
4796 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4797 		int hash;
4798 		list_del_init(&sh->lru);
4799 		atomic_inc(&sh->count);
4800 		hash = sh->hash_lock_index;
4801 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
4802 	}
4803 }
4804 
4805 static int raid5_congested(struct mddev *mddev, int bits)
4806 {
4807 	struct r5conf *conf = mddev->private;
4808 
4809 	/* No difference between reads and writes.  Just check
4810 	 * how busy the stripe_cache is
4811 	 */
4812 
4813 	if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
4814 		return 1;
4815 
4816 	/* Also checks whether there is pressure on r5cache log space */
4817 	if (test_bit(R5C_LOG_TIGHT, &conf->cache_state))
4818 		return 1;
4819 	if (conf->quiesce)
4820 		return 1;
4821 	if (atomic_read(&conf->empty_inactive_list_nr))
4822 		return 1;
4823 
4824 	return 0;
4825 }
4826 
4827 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4828 {
4829 	struct r5conf *conf = mddev->private;
4830 	sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4831 	unsigned int chunk_sectors;
4832 	unsigned int bio_sectors = bio_sectors(bio);
4833 
4834 	chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
4835 	return  chunk_sectors >=
4836 		((sector & (chunk_sectors - 1)) + bio_sectors);
4837 }
4838 
4839 /*
4840  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4841  *  later sampled by raid5d.
4842  */
4843 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4844 {
4845 	unsigned long flags;
4846 
4847 	spin_lock_irqsave(&conf->device_lock, flags);
4848 
4849 	bi->bi_next = conf->retry_read_aligned_list;
4850 	conf->retry_read_aligned_list = bi;
4851 
4852 	spin_unlock_irqrestore(&conf->device_lock, flags);
4853 	md_wakeup_thread(conf->mddev->thread);
4854 }
4855 
4856 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4857 {
4858 	struct bio *bi;
4859 
4860 	bi = conf->retry_read_aligned;
4861 	if (bi) {
4862 		conf->retry_read_aligned = NULL;
4863 		return bi;
4864 	}
4865 	bi = conf->retry_read_aligned_list;
4866 	if(bi) {
4867 		conf->retry_read_aligned_list = bi->bi_next;
4868 		bi->bi_next = NULL;
4869 		/*
4870 		 * this sets the active strip count to 1 and the processed
4871 		 * strip count to zero (upper 8 bits)
4872 		 */
4873 		raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
4874 	}
4875 
4876 	return bi;
4877 }
4878 
4879 /*
4880  *  The "raid5_align_endio" should check if the read succeeded and if it
4881  *  did, call bio_endio on the original bio (having bio_put the new bio
4882  *  first).
4883  *  If the read failed..
4884  */
4885 static void raid5_align_endio(struct bio *bi)
4886 {
4887 	struct bio* raid_bi  = bi->bi_private;
4888 	struct mddev *mddev;
4889 	struct r5conf *conf;
4890 	struct md_rdev *rdev;
4891 	int error = bi->bi_error;
4892 
4893 	bio_put(bi);
4894 
4895 	rdev = (void*)raid_bi->bi_next;
4896 	raid_bi->bi_next = NULL;
4897 	mddev = rdev->mddev;
4898 	conf = mddev->private;
4899 
4900 	rdev_dec_pending(rdev, conf->mddev);
4901 
4902 	if (!error) {
4903 		trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
4904 					 raid_bi, 0);
4905 		bio_endio(raid_bi);
4906 		if (atomic_dec_and_test(&conf->active_aligned_reads))
4907 			wake_up(&conf->wait_for_quiescent);
4908 		return;
4909 	}
4910 
4911 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
4912 
4913 	add_bio_to_retry(raid_bi, conf);
4914 }
4915 
4916 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
4917 {
4918 	struct r5conf *conf = mddev->private;
4919 	int dd_idx;
4920 	struct bio* align_bi;
4921 	struct md_rdev *rdev;
4922 	sector_t end_sector;
4923 
4924 	if (!in_chunk_boundary(mddev, raid_bio)) {
4925 		pr_debug("%s: non aligned\n", __func__);
4926 		return 0;
4927 	}
4928 	/*
4929 	 * use bio_clone_mddev to make a copy of the bio
4930 	 */
4931 	align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4932 	if (!align_bi)
4933 		return 0;
4934 	/*
4935 	 *   set bi_end_io to a new function, and set bi_private to the
4936 	 *     original bio.
4937 	 */
4938 	align_bi->bi_end_io  = raid5_align_endio;
4939 	align_bi->bi_private = raid_bio;
4940 	/*
4941 	 *	compute position
4942 	 */
4943 	align_bi->bi_iter.bi_sector =
4944 		raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
4945 				     0, &dd_idx, NULL);
4946 
4947 	end_sector = bio_end_sector(align_bi);
4948 	rcu_read_lock();
4949 	rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4950 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
4951 	    rdev->recovery_offset < end_sector) {
4952 		rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4953 		if (rdev &&
4954 		    (test_bit(Faulty, &rdev->flags) ||
4955 		    !(test_bit(In_sync, &rdev->flags) ||
4956 		      rdev->recovery_offset >= end_sector)))
4957 			rdev = NULL;
4958 	}
4959 	if (rdev) {
4960 		sector_t first_bad;
4961 		int bad_sectors;
4962 
4963 		atomic_inc(&rdev->nr_pending);
4964 		rcu_read_unlock();
4965 		raid_bio->bi_next = (void*)rdev;
4966 		align_bi->bi_bdev =  rdev->bdev;
4967 		bio_clear_flag(align_bi, BIO_SEG_VALID);
4968 
4969 		if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
4970 				bio_sectors(align_bi),
4971 				&first_bad, &bad_sectors)) {
4972 			bio_put(align_bi);
4973 			rdev_dec_pending(rdev, mddev);
4974 			return 0;
4975 		}
4976 
4977 		/* No reshape active, so we can trust rdev->data_offset */
4978 		align_bi->bi_iter.bi_sector += rdev->data_offset;
4979 
4980 		spin_lock_irq(&conf->device_lock);
4981 		wait_event_lock_irq(conf->wait_for_quiescent,
4982 				    conf->quiesce == 0,
4983 				    conf->device_lock);
4984 		atomic_inc(&conf->active_aligned_reads);
4985 		spin_unlock_irq(&conf->device_lock);
4986 
4987 		if (mddev->gendisk)
4988 			trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4989 					      align_bi, disk_devt(mddev->gendisk),
4990 					      raid_bio->bi_iter.bi_sector);
4991 		generic_make_request(align_bi);
4992 		return 1;
4993 	} else {
4994 		rcu_read_unlock();
4995 		bio_put(align_bi);
4996 		return 0;
4997 	}
4998 }
4999 
5000 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
5001 {
5002 	struct bio *split;
5003 
5004 	do {
5005 		sector_t sector = raid_bio->bi_iter.bi_sector;
5006 		unsigned chunk_sects = mddev->chunk_sectors;
5007 		unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
5008 
5009 		if (sectors < bio_sectors(raid_bio)) {
5010 			split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);
5011 			bio_chain(split, raid_bio);
5012 		} else
5013 			split = raid_bio;
5014 
5015 		if (!raid5_read_one_chunk(mddev, split)) {
5016 			if (split != raid_bio)
5017 				generic_make_request(raid_bio);
5018 			return split;
5019 		}
5020 	} while (split != raid_bio);
5021 
5022 	return NULL;
5023 }
5024 
5025 /* __get_priority_stripe - get the next stripe to process
5026  *
5027  * Full stripe writes are allowed to pass preread active stripes up until
5028  * the bypass_threshold is exceeded.  In general the bypass_count
5029  * increments when the handle_list is handled before the hold_list; however, it
5030  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
5031  * stripe with in flight i/o.  The bypass_count will be reset when the
5032  * head of the hold_list has changed, i.e. the head was promoted to the
5033  * handle_list.
5034  */
5035 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
5036 {
5037 	struct stripe_head *sh = NULL, *tmp;
5038 	struct list_head *handle_list = NULL;
5039 	struct r5worker_group *wg = NULL;
5040 
5041 	if (conf->worker_cnt_per_group == 0) {
5042 		handle_list = &conf->handle_list;
5043 	} else if (group != ANY_GROUP) {
5044 		handle_list = &conf->worker_groups[group].handle_list;
5045 		wg = &conf->worker_groups[group];
5046 	} else {
5047 		int i;
5048 		for (i = 0; i < conf->group_cnt; i++) {
5049 			handle_list = &conf->worker_groups[i].handle_list;
5050 			wg = &conf->worker_groups[i];
5051 			if (!list_empty(handle_list))
5052 				break;
5053 		}
5054 	}
5055 
5056 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
5057 		  __func__,
5058 		  list_empty(handle_list) ? "empty" : "busy",
5059 		  list_empty(&conf->hold_list) ? "empty" : "busy",
5060 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
5061 
5062 	if (!list_empty(handle_list)) {
5063 		sh = list_entry(handle_list->next, typeof(*sh), lru);
5064 
5065 		if (list_empty(&conf->hold_list))
5066 			conf->bypass_count = 0;
5067 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
5068 			if (conf->hold_list.next == conf->last_hold)
5069 				conf->bypass_count++;
5070 			else {
5071 				conf->last_hold = conf->hold_list.next;
5072 				conf->bypass_count -= conf->bypass_threshold;
5073 				if (conf->bypass_count < 0)
5074 					conf->bypass_count = 0;
5075 			}
5076 		}
5077 	} else if (!list_empty(&conf->hold_list) &&
5078 		   ((conf->bypass_threshold &&
5079 		     conf->bypass_count > conf->bypass_threshold) ||
5080 		    atomic_read(&conf->pending_full_writes) == 0)) {
5081 
5082 		list_for_each_entry(tmp, &conf->hold_list,  lru) {
5083 			if (conf->worker_cnt_per_group == 0 ||
5084 			    group == ANY_GROUP ||
5085 			    !cpu_online(tmp->cpu) ||
5086 			    cpu_to_group(tmp->cpu) == group) {
5087 				sh = tmp;
5088 				break;
5089 			}
5090 		}
5091 
5092 		if (sh) {
5093 			conf->bypass_count -= conf->bypass_threshold;
5094 			if (conf->bypass_count < 0)
5095 				conf->bypass_count = 0;
5096 		}
5097 		wg = NULL;
5098 	}
5099 
5100 	if (!sh)
5101 		return NULL;
5102 
5103 	if (wg) {
5104 		wg->stripes_cnt--;
5105 		sh->group = NULL;
5106 	}
5107 	list_del_init(&sh->lru);
5108 	BUG_ON(atomic_inc_return(&sh->count) != 1);
5109 	return sh;
5110 }
5111 
5112 struct raid5_plug_cb {
5113 	struct blk_plug_cb	cb;
5114 	struct list_head	list;
5115 	struct list_head	temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5116 };
5117 
5118 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5119 {
5120 	struct raid5_plug_cb *cb = container_of(
5121 		blk_cb, struct raid5_plug_cb, cb);
5122 	struct stripe_head *sh;
5123 	struct mddev *mddev = cb->cb.data;
5124 	struct r5conf *conf = mddev->private;
5125 	int cnt = 0;
5126 	int hash;
5127 
5128 	if (cb->list.next && !list_empty(&cb->list)) {
5129 		spin_lock_irq(&conf->device_lock);
5130 		while (!list_empty(&cb->list)) {
5131 			sh = list_first_entry(&cb->list, struct stripe_head, lru);
5132 			list_del_init(&sh->lru);
5133 			/*
5134 			 * avoid race release_stripe_plug() sees
5135 			 * STRIPE_ON_UNPLUG_LIST clear but the stripe
5136 			 * is still in our list
5137 			 */
5138 			smp_mb__before_atomic();
5139 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5140 			/*
5141 			 * STRIPE_ON_RELEASE_LIST could be set here. In that
5142 			 * case, the count is always > 1 here
5143 			 */
5144 			hash = sh->hash_lock_index;
5145 			__release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5146 			cnt++;
5147 		}
5148 		spin_unlock_irq(&conf->device_lock);
5149 	}
5150 	release_inactive_stripe_list(conf, cb->temp_inactive_list,
5151 				     NR_STRIPE_HASH_LOCKS);
5152 	if (mddev->queue)
5153 		trace_block_unplug(mddev->queue, cnt, !from_schedule);
5154 	kfree(cb);
5155 }
5156 
5157 static void release_stripe_plug(struct mddev *mddev,
5158 				struct stripe_head *sh)
5159 {
5160 	struct blk_plug_cb *blk_cb = blk_check_plugged(
5161 		raid5_unplug, mddev,
5162 		sizeof(struct raid5_plug_cb));
5163 	struct raid5_plug_cb *cb;
5164 
5165 	if (!blk_cb) {
5166 		raid5_release_stripe(sh);
5167 		return;
5168 	}
5169 
5170 	cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5171 
5172 	if (cb->list.next == NULL) {
5173 		int i;
5174 		INIT_LIST_HEAD(&cb->list);
5175 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5176 			INIT_LIST_HEAD(cb->temp_inactive_list + i);
5177 	}
5178 
5179 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5180 		list_add_tail(&sh->lru, &cb->list);
5181 	else
5182 		raid5_release_stripe(sh);
5183 }
5184 
5185 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5186 {
5187 	struct r5conf *conf = mddev->private;
5188 	sector_t logical_sector, last_sector;
5189 	struct stripe_head *sh;
5190 	int remaining;
5191 	int stripe_sectors;
5192 
5193 	if (mddev->reshape_position != MaxSector)
5194 		/* Skip discard while reshape is happening */
5195 		return;
5196 
5197 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5198 	last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5199 
5200 	bi->bi_next = NULL;
5201 	bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
5202 
5203 	stripe_sectors = conf->chunk_sectors *
5204 		(conf->raid_disks - conf->max_degraded);
5205 	logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5206 					       stripe_sectors);
5207 	sector_div(last_sector, stripe_sectors);
5208 
5209 	logical_sector *= conf->chunk_sectors;
5210 	last_sector *= conf->chunk_sectors;
5211 
5212 	for (; logical_sector < last_sector;
5213 	     logical_sector += STRIPE_SECTORS) {
5214 		DEFINE_WAIT(w);
5215 		int d;
5216 	again:
5217 		sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
5218 		prepare_to_wait(&conf->wait_for_overlap, &w,
5219 				TASK_UNINTERRUPTIBLE);
5220 		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5221 		if (test_bit(STRIPE_SYNCING, &sh->state)) {
5222 			raid5_release_stripe(sh);
5223 			schedule();
5224 			goto again;
5225 		}
5226 		clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5227 		spin_lock_irq(&sh->stripe_lock);
5228 		for (d = 0; d < conf->raid_disks; d++) {
5229 			if (d == sh->pd_idx || d == sh->qd_idx)
5230 				continue;
5231 			if (sh->dev[d].towrite || sh->dev[d].toread) {
5232 				set_bit(R5_Overlap, &sh->dev[d].flags);
5233 				spin_unlock_irq(&sh->stripe_lock);
5234 				raid5_release_stripe(sh);
5235 				schedule();
5236 				goto again;
5237 			}
5238 		}
5239 		set_bit(STRIPE_DISCARD, &sh->state);
5240 		finish_wait(&conf->wait_for_overlap, &w);
5241 		sh->overwrite_disks = 0;
5242 		for (d = 0; d < conf->raid_disks; d++) {
5243 			if (d == sh->pd_idx || d == sh->qd_idx)
5244 				continue;
5245 			sh->dev[d].towrite = bi;
5246 			set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5247 			raid5_inc_bi_active_stripes(bi);
5248 			sh->overwrite_disks++;
5249 		}
5250 		spin_unlock_irq(&sh->stripe_lock);
5251 		if (conf->mddev->bitmap) {
5252 			for (d = 0;
5253 			     d < conf->raid_disks - conf->max_degraded;
5254 			     d++)
5255 				bitmap_startwrite(mddev->bitmap,
5256 						  sh->sector,
5257 						  STRIPE_SECTORS,
5258 						  0);
5259 			sh->bm_seq = conf->seq_flush + 1;
5260 			set_bit(STRIPE_BIT_DELAY, &sh->state);
5261 		}
5262 
5263 		set_bit(STRIPE_HANDLE, &sh->state);
5264 		clear_bit(STRIPE_DELAYED, &sh->state);
5265 		if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5266 			atomic_inc(&conf->preread_active_stripes);
5267 		release_stripe_plug(mddev, sh);
5268 	}
5269 
5270 	remaining = raid5_dec_bi_active_stripes(bi);
5271 	if (remaining == 0) {
5272 		md_write_end(mddev);
5273 		bio_endio(bi);
5274 	}
5275 }
5276 
5277 static void raid5_make_request(struct mddev *mddev, struct bio * bi)
5278 {
5279 	struct r5conf *conf = mddev->private;
5280 	int dd_idx;
5281 	sector_t new_sector;
5282 	sector_t logical_sector, last_sector;
5283 	struct stripe_head *sh;
5284 	const int rw = bio_data_dir(bi);
5285 	int remaining;
5286 	DEFINE_WAIT(w);
5287 	bool do_prepare;
5288 	bool do_flush = false;
5289 
5290 	if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
5291 		int ret = r5l_handle_flush_request(conf->log, bi);
5292 
5293 		if (ret == 0)
5294 			return;
5295 		if (ret == -ENODEV) {
5296 			md_flush_request(mddev, bi);
5297 			return;
5298 		}
5299 		/* ret == -EAGAIN, fallback */
5300 		/*
5301 		 * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
5302 		 * we need to flush journal device
5303 		 */
5304 		do_flush = bi->bi_opf & REQ_PREFLUSH;
5305 	}
5306 
5307 	md_write_start(mddev, bi);
5308 
5309 	/*
5310 	 * If array is degraded, better not do chunk aligned read because
5311 	 * later we might have to read it again in order to reconstruct
5312 	 * data on failed drives.
5313 	 */
5314 	if (rw == READ && mddev->degraded == 0 &&
5315 	    !r5c_is_writeback(conf->log) &&
5316 	    mddev->reshape_position == MaxSector) {
5317 		bi = chunk_aligned_read(mddev, bi);
5318 		if (!bi)
5319 			return;
5320 	}
5321 
5322 	if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) {
5323 		make_discard_request(mddev, bi);
5324 		return;
5325 	}
5326 
5327 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5328 	last_sector = bio_end_sector(bi);
5329 	bi->bi_next = NULL;
5330 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
5331 
5332 	prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5333 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5334 		int previous;
5335 		int seq;
5336 
5337 		do_prepare = false;
5338 	retry:
5339 		seq = read_seqcount_begin(&conf->gen_lock);
5340 		previous = 0;
5341 		if (do_prepare)
5342 			prepare_to_wait(&conf->wait_for_overlap, &w,
5343 				TASK_UNINTERRUPTIBLE);
5344 		if (unlikely(conf->reshape_progress != MaxSector)) {
5345 			/* spinlock is needed as reshape_progress may be
5346 			 * 64bit on a 32bit platform, and so it might be
5347 			 * possible to see a half-updated value
5348 			 * Of course reshape_progress could change after
5349 			 * the lock is dropped, so once we get a reference
5350 			 * to the stripe that we think it is, we will have
5351 			 * to check again.
5352 			 */
5353 			spin_lock_irq(&conf->device_lock);
5354 			if (mddev->reshape_backwards
5355 			    ? logical_sector < conf->reshape_progress
5356 			    : logical_sector >= conf->reshape_progress) {
5357 				previous = 1;
5358 			} else {
5359 				if (mddev->reshape_backwards
5360 				    ? logical_sector < conf->reshape_safe
5361 				    : logical_sector >= conf->reshape_safe) {
5362 					spin_unlock_irq(&conf->device_lock);
5363 					schedule();
5364 					do_prepare = true;
5365 					goto retry;
5366 				}
5367 			}
5368 			spin_unlock_irq(&conf->device_lock);
5369 		}
5370 
5371 		new_sector = raid5_compute_sector(conf, logical_sector,
5372 						  previous,
5373 						  &dd_idx, NULL);
5374 		pr_debug("raid456: raid5_make_request, sector %llu logical %llu\n",
5375 			(unsigned long long)new_sector,
5376 			(unsigned long long)logical_sector);
5377 
5378 		sh = raid5_get_active_stripe(conf, new_sector, previous,
5379 				       (bi->bi_opf & REQ_RAHEAD), 0);
5380 		if (sh) {
5381 			if (unlikely(previous)) {
5382 				/* expansion might have moved on while waiting for a
5383 				 * stripe, so we must do the range check again.
5384 				 * Expansion could still move past after this
5385 				 * test, but as we are holding a reference to
5386 				 * 'sh', we know that if that happens,
5387 				 *  STRIPE_EXPANDING will get set and the expansion
5388 				 * won't proceed until we finish with the stripe.
5389 				 */
5390 				int must_retry = 0;
5391 				spin_lock_irq(&conf->device_lock);
5392 				if (mddev->reshape_backwards
5393 				    ? logical_sector >= conf->reshape_progress
5394 				    : logical_sector < conf->reshape_progress)
5395 					/* mismatch, need to try again */
5396 					must_retry = 1;
5397 				spin_unlock_irq(&conf->device_lock);
5398 				if (must_retry) {
5399 					raid5_release_stripe(sh);
5400 					schedule();
5401 					do_prepare = true;
5402 					goto retry;
5403 				}
5404 			}
5405 			if (read_seqcount_retry(&conf->gen_lock, seq)) {
5406 				/* Might have got the wrong stripe_head
5407 				 * by accident
5408 				 */
5409 				raid5_release_stripe(sh);
5410 				goto retry;
5411 			}
5412 
5413 			if (rw == WRITE &&
5414 			    logical_sector >= mddev->suspend_lo &&
5415 			    logical_sector < mddev->suspend_hi) {
5416 				raid5_release_stripe(sh);
5417 				/* As the suspend_* range is controlled by
5418 				 * userspace, we want an interruptible
5419 				 * wait.
5420 				 */
5421 				flush_signals(current);
5422 				prepare_to_wait(&conf->wait_for_overlap,
5423 						&w, TASK_INTERRUPTIBLE);
5424 				if (logical_sector >= mddev->suspend_lo &&
5425 				    logical_sector < mddev->suspend_hi) {
5426 					schedule();
5427 					do_prepare = true;
5428 				}
5429 				goto retry;
5430 			}
5431 
5432 			if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5433 			    !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5434 				/* Stripe is busy expanding or
5435 				 * add failed due to overlap.  Flush everything
5436 				 * and wait a while
5437 				 */
5438 				md_wakeup_thread(mddev->thread);
5439 				raid5_release_stripe(sh);
5440 				schedule();
5441 				do_prepare = true;
5442 				goto retry;
5443 			}
5444 			if (do_flush) {
5445 				set_bit(STRIPE_R5C_PREFLUSH, &sh->state);
5446 				/* we only need flush for one stripe */
5447 				do_flush = false;
5448 			}
5449 
5450 			set_bit(STRIPE_HANDLE, &sh->state);
5451 			clear_bit(STRIPE_DELAYED, &sh->state);
5452 			if ((!sh->batch_head || sh == sh->batch_head) &&
5453 			    (bi->bi_opf & REQ_SYNC) &&
5454 			    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5455 				atomic_inc(&conf->preread_active_stripes);
5456 			release_stripe_plug(mddev, sh);
5457 		} else {
5458 			/* cannot get stripe for read-ahead, just give-up */
5459 			bi->bi_error = -EIO;
5460 			break;
5461 		}
5462 	}
5463 	finish_wait(&conf->wait_for_overlap, &w);
5464 
5465 	remaining = raid5_dec_bi_active_stripes(bi);
5466 	if (remaining == 0) {
5467 
5468 		if ( rw == WRITE )
5469 			md_write_end(mddev);
5470 
5471 		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
5472 					 bi, 0);
5473 		bio_endio(bi);
5474 	}
5475 }
5476 
5477 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5478 
5479 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5480 {
5481 	/* reshaping is quite different to recovery/resync so it is
5482 	 * handled quite separately ... here.
5483 	 *
5484 	 * On each call to sync_request, we gather one chunk worth of
5485 	 * destination stripes and flag them as expanding.
5486 	 * Then we find all the source stripes and request reads.
5487 	 * As the reads complete, handle_stripe will copy the data
5488 	 * into the destination stripe and release that stripe.
5489 	 */
5490 	struct r5conf *conf = mddev->private;
5491 	struct stripe_head *sh;
5492 	sector_t first_sector, last_sector;
5493 	int raid_disks = conf->previous_raid_disks;
5494 	int data_disks = raid_disks - conf->max_degraded;
5495 	int new_data_disks = conf->raid_disks - conf->max_degraded;
5496 	int i;
5497 	int dd_idx;
5498 	sector_t writepos, readpos, safepos;
5499 	sector_t stripe_addr;
5500 	int reshape_sectors;
5501 	struct list_head stripes;
5502 	sector_t retn;
5503 
5504 	if (sector_nr == 0) {
5505 		/* If restarting in the middle, skip the initial sectors */
5506 		if (mddev->reshape_backwards &&
5507 		    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5508 			sector_nr = raid5_size(mddev, 0, 0)
5509 				- conf->reshape_progress;
5510 		} else if (mddev->reshape_backwards &&
5511 			   conf->reshape_progress == MaxSector) {
5512 			/* shouldn't happen, but just in case, finish up.*/
5513 			sector_nr = MaxSector;
5514 		} else if (!mddev->reshape_backwards &&
5515 			   conf->reshape_progress > 0)
5516 			sector_nr = conf->reshape_progress;
5517 		sector_div(sector_nr, new_data_disks);
5518 		if (sector_nr) {
5519 			mddev->curr_resync_completed = sector_nr;
5520 			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5521 			*skipped = 1;
5522 			retn = sector_nr;
5523 			goto finish;
5524 		}
5525 	}
5526 
5527 	/* We need to process a full chunk at a time.
5528 	 * If old and new chunk sizes differ, we need to process the
5529 	 * largest of these
5530 	 */
5531 
5532 	reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
5533 
5534 	/* We update the metadata at least every 10 seconds, or when
5535 	 * the data about to be copied would over-write the source of
5536 	 * the data at the front of the range.  i.e. one new_stripe
5537 	 * along from reshape_progress new_maps to after where
5538 	 * reshape_safe old_maps to
5539 	 */
5540 	writepos = conf->reshape_progress;
5541 	sector_div(writepos, new_data_disks);
5542 	readpos = conf->reshape_progress;
5543 	sector_div(readpos, data_disks);
5544 	safepos = conf->reshape_safe;
5545 	sector_div(safepos, data_disks);
5546 	if (mddev->reshape_backwards) {
5547 		BUG_ON(writepos < reshape_sectors);
5548 		writepos -= reshape_sectors;
5549 		readpos += reshape_sectors;
5550 		safepos += reshape_sectors;
5551 	} else {
5552 		writepos += reshape_sectors;
5553 		/* readpos and safepos are worst-case calculations.
5554 		 * A negative number is overly pessimistic, and causes
5555 		 * obvious problems for unsigned storage.  So clip to 0.
5556 		 */
5557 		readpos -= min_t(sector_t, reshape_sectors, readpos);
5558 		safepos -= min_t(sector_t, reshape_sectors, safepos);
5559 	}
5560 
5561 	/* Having calculated the 'writepos' possibly use it
5562 	 * to set 'stripe_addr' which is where we will write to.
5563 	 */
5564 	if (mddev->reshape_backwards) {
5565 		BUG_ON(conf->reshape_progress == 0);
5566 		stripe_addr = writepos;
5567 		BUG_ON((mddev->dev_sectors &
5568 			~((sector_t)reshape_sectors - 1))
5569 		       - reshape_sectors - stripe_addr
5570 		       != sector_nr);
5571 	} else {
5572 		BUG_ON(writepos != sector_nr + reshape_sectors);
5573 		stripe_addr = sector_nr;
5574 	}
5575 
5576 	/* 'writepos' is the most advanced device address we might write.
5577 	 * 'readpos' is the least advanced device address we might read.
5578 	 * 'safepos' is the least address recorded in the metadata as having
5579 	 *     been reshaped.
5580 	 * If there is a min_offset_diff, these are adjusted either by
5581 	 * increasing the safepos/readpos if diff is negative, or
5582 	 * increasing writepos if diff is positive.
5583 	 * If 'readpos' is then behind 'writepos', there is no way that we can
5584 	 * ensure safety in the face of a crash - that must be done by userspace
5585 	 * making a backup of the data.  So in that case there is no particular
5586 	 * rush to update metadata.
5587 	 * Otherwise if 'safepos' is behind 'writepos', then we really need to
5588 	 * update the metadata to advance 'safepos' to match 'readpos' so that
5589 	 * we can be safe in the event of a crash.
5590 	 * So we insist on updating metadata if safepos is behind writepos and
5591 	 * readpos is beyond writepos.
5592 	 * In any case, update the metadata every 10 seconds.
5593 	 * Maybe that number should be configurable, but I'm not sure it is
5594 	 * worth it.... maybe it could be a multiple of safemode_delay???
5595 	 */
5596 	if (conf->min_offset_diff < 0) {
5597 		safepos += -conf->min_offset_diff;
5598 		readpos += -conf->min_offset_diff;
5599 	} else
5600 		writepos += conf->min_offset_diff;
5601 
5602 	if ((mddev->reshape_backwards
5603 	     ? (safepos > writepos && readpos < writepos)
5604 	     : (safepos < writepos && readpos > writepos)) ||
5605 	    time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5606 		/* Cannot proceed until we've updated the superblock... */
5607 		wait_event(conf->wait_for_overlap,
5608 			   atomic_read(&conf->reshape_stripes)==0
5609 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5610 		if (atomic_read(&conf->reshape_stripes) != 0)
5611 			return 0;
5612 		mddev->reshape_position = conf->reshape_progress;
5613 		mddev->curr_resync_completed = sector_nr;
5614 		conf->reshape_checkpoint = jiffies;
5615 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5616 		md_wakeup_thread(mddev->thread);
5617 		wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
5618 			   test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5619 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5620 			return 0;
5621 		spin_lock_irq(&conf->device_lock);
5622 		conf->reshape_safe = mddev->reshape_position;
5623 		spin_unlock_irq(&conf->device_lock);
5624 		wake_up(&conf->wait_for_overlap);
5625 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5626 	}
5627 
5628 	INIT_LIST_HEAD(&stripes);
5629 	for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5630 		int j;
5631 		int skipped_disk = 0;
5632 		sh = raid5_get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5633 		set_bit(STRIPE_EXPANDING, &sh->state);
5634 		atomic_inc(&conf->reshape_stripes);
5635 		/* If any of this stripe is beyond the end of the old
5636 		 * array, then we need to zero those blocks
5637 		 */
5638 		for (j=sh->disks; j--;) {
5639 			sector_t s;
5640 			if (j == sh->pd_idx)
5641 				continue;
5642 			if (conf->level == 6 &&
5643 			    j == sh->qd_idx)
5644 				continue;
5645 			s = raid5_compute_blocknr(sh, j, 0);
5646 			if (s < raid5_size(mddev, 0, 0)) {
5647 				skipped_disk = 1;
5648 				continue;
5649 			}
5650 			memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5651 			set_bit(R5_Expanded, &sh->dev[j].flags);
5652 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
5653 		}
5654 		if (!skipped_disk) {
5655 			set_bit(STRIPE_EXPAND_READY, &sh->state);
5656 			set_bit(STRIPE_HANDLE, &sh->state);
5657 		}
5658 		list_add(&sh->lru, &stripes);
5659 	}
5660 	spin_lock_irq(&conf->device_lock);
5661 	if (mddev->reshape_backwards)
5662 		conf->reshape_progress -= reshape_sectors * new_data_disks;
5663 	else
5664 		conf->reshape_progress += reshape_sectors * new_data_disks;
5665 	spin_unlock_irq(&conf->device_lock);
5666 	/* Ok, those stripe are ready. We can start scheduling
5667 	 * reads on the source stripes.
5668 	 * The source stripes are determined by mapping the first and last
5669 	 * block on the destination stripes.
5670 	 */
5671 	first_sector =
5672 		raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5673 				     1, &dd_idx, NULL);
5674 	last_sector =
5675 		raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5676 					    * new_data_disks - 1),
5677 				     1, &dd_idx, NULL);
5678 	if (last_sector >= mddev->dev_sectors)
5679 		last_sector = mddev->dev_sectors - 1;
5680 	while (first_sector <= last_sector) {
5681 		sh = raid5_get_active_stripe(conf, first_sector, 1, 0, 1);
5682 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5683 		set_bit(STRIPE_HANDLE, &sh->state);
5684 		raid5_release_stripe(sh);
5685 		first_sector += STRIPE_SECTORS;
5686 	}
5687 	/* Now that the sources are clearly marked, we can release
5688 	 * the destination stripes
5689 	 */
5690 	while (!list_empty(&stripes)) {
5691 		sh = list_entry(stripes.next, struct stripe_head, lru);
5692 		list_del_init(&sh->lru);
5693 		raid5_release_stripe(sh);
5694 	}
5695 	/* If this takes us to the resync_max point where we have to pause,
5696 	 * then we need to write out the superblock.
5697 	 */
5698 	sector_nr += reshape_sectors;
5699 	retn = reshape_sectors;
5700 finish:
5701 	if (mddev->curr_resync_completed > mddev->resync_max ||
5702 	    (sector_nr - mddev->curr_resync_completed) * 2
5703 	    >= mddev->resync_max - mddev->curr_resync_completed) {
5704 		/* Cannot proceed until we've updated the superblock... */
5705 		wait_event(conf->wait_for_overlap,
5706 			   atomic_read(&conf->reshape_stripes) == 0
5707 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5708 		if (atomic_read(&conf->reshape_stripes) != 0)
5709 			goto ret;
5710 		mddev->reshape_position = conf->reshape_progress;
5711 		mddev->curr_resync_completed = sector_nr;
5712 		conf->reshape_checkpoint = jiffies;
5713 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5714 		md_wakeup_thread(mddev->thread);
5715 		wait_event(mddev->sb_wait,
5716 			   !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)
5717 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5718 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5719 			goto ret;
5720 		spin_lock_irq(&conf->device_lock);
5721 		conf->reshape_safe = mddev->reshape_position;
5722 		spin_unlock_irq(&conf->device_lock);
5723 		wake_up(&conf->wait_for_overlap);
5724 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5725 	}
5726 ret:
5727 	return retn;
5728 }
5729 
5730 static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_nr,
5731 					  int *skipped)
5732 {
5733 	struct r5conf *conf = mddev->private;
5734 	struct stripe_head *sh;
5735 	sector_t max_sector = mddev->dev_sectors;
5736 	sector_t sync_blocks;
5737 	int still_degraded = 0;
5738 	int i;
5739 
5740 	if (sector_nr >= max_sector) {
5741 		/* just being told to finish up .. nothing much to do */
5742 
5743 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5744 			end_reshape(conf);
5745 			return 0;
5746 		}
5747 
5748 		if (mddev->curr_resync < max_sector) /* aborted */
5749 			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5750 					&sync_blocks, 1);
5751 		else /* completed sync */
5752 			conf->fullsync = 0;
5753 		bitmap_close_sync(mddev->bitmap);
5754 
5755 		return 0;
5756 	}
5757 
5758 	/* Allow raid5_quiesce to complete */
5759 	wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5760 
5761 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5762 		return reshape_request(mddev, sector_nr, skipped);
5763 
5764 	/* No need to check resync_max as we never do more than one
5765 	 * stripe, and as resync_max will always be on a chunk boundary,
5766 	 * if the check in md_do_sync didn't fire, there is no chance
5767 	 * of overstepping resync_max here
5768 	 */
5769 
5770 	/* if there is too many failed drives and we are trying
5771 	 * to resync, then assert that we are finished, because there is
5772 	 * nothing we can do.
5773 	 */
5774 	if (mddev->degraded >= conf->max_degraded &&
5775 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5776 		sector_t rv = mddev->dev_sectors - sector_nr;
5777 		*skipped = 1;
5778 		return rv;
5779 	}
5780 	if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5781 	    !conf->fullsync &&
5782 	    !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5783 	    sync_blocks >= STRIPE_SECTORS) {
5784 		/* we can skip this block, and probably more */
5785 		sync_blocks /= STRIPE_SECTORS;
5786 		*skipped = 1;
5787 		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5788 	}
5789 
5790 	bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
5791 
5792 	sh = raid5_get_active_stripe(conf, sector_nr, 0, 1, 0);
5793 	if (sh == NULL) {
5794 		sh = raid5_get_active_stripe(conf, sector_nr, 0, 0, 0);
5795 		/* make sure we don't swamp the stripe cache if someone else
5796 		 * is trying to get access
5797 		 */
5798 		schedule_timeout_uninterruptible(1);
5799 	}
5800 	/* Need to check if array will still be degraded after recovery/resync
5801 	 * Note in case of > 1 drive failures it's possible we're rebuilding
5802 	 * one drive while leaving another faulty drive in array.
5803 	 */
5804 	rcu_read_lock();
5805 	for (i = 0; i < conf->raid_disks; i++) {
5806 		struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
5807 
5808 		if (rdev == NULL || test_bit(Faulty, &rdev->flags))
5809 			still_degraded = 1;
5810 	}
5811 	rcu_read_unlock();
5812 
5813 	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5814 
5815 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5816 	set_bit(STRIPE_HANDLE, &sh->state);
5817 
5818 	raid5_release_stripe(sh);
5819 
5820 	return STRIPE_SECTORS;
5821 }
5822 
5823 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5824 {
5825 	/* We may not be able to submit a whole bio at once as there
5826 	 * may not be enough stripe_heads available.
5827 	 * We cannot pre-allocate enough stripe_heads as we may need
5828 	 * more than exist in the cache (if we allow ever large chunks).
5829 	 * So we do one stripe head at a time and record in
5830 	 * ->bi_hw_segments how many have been done.
5831 	 *
5832 	 * We *know* that this entire raid_bio is in one chunk, so
5833 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5834 	 */
5835 	struct stripe_head *sh;
5836 	int dd_idx;
5837 	sector_t sector, logical_sector, last_sector;
5838 	int scnt = 0;
5839 	int remaining;
5840 	int handled = 0;
5841 
5842 	logical_sector = raid_bio->bi_iter.bi_sector &
5843 		~((sector_t)STRIPE_SECTORS-1);
5844 	sector = raid5_compute_sector(conf, logical_sector,
5845 				      0, &dd_idx, NULL);
5846 	last_sector = bio_end_sector(raid_bio);
5847 
5848 	for (; logical_sector < last_sector;
5849 	     logical_sector += STRIPE_SECTORS,
5850 		     sector += STRIPE_SECTORS,
5851 		     scnt++) {
5852 
5853 		if (scnt < raid5_bi_processed_stripes(raid_bio))
5854 			/* already done this stripe */
5855 			continue;
5856 
5857 		sh = raid5_get_active_stripe(conf, sector, 0, 1, 1);
5858 
5859 		if (!sh) {
5860 			/* failed to get a stripe - must wait */
5861 			raid5_set_bi_processed_stripes(raid_bio, scnt);
5862 			conf->retry_read_aligned = raid_bio;
5863 			return handled;
5864 		}
5865 
5866 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
5867 			raid5_release_stripe(sh);
5868 			raid5_set_bi_processed_stripes(raid_bio, scnt);
5869 			conf->retry_read_aligned = raid_bio;
5870 			return handled;
5871 		}
5872 
5873 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
5874 		handle_stripe(sh);
5875 		raid5_release_stripe(sh);
5876 		handled++;
5877 	}
5878 	remaining = raid5_dec_bi_active_stripes(raid_bio);
5879 	if (remaining == 0) {
5880 		trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
5881 					 raid_bio, 0);
5882 		bio_endio(raid_bio);
5883 	}
5884 	if (atomic_dec_and_test(&conf->active_aligned_reads))
5885 		wake_up(&conf->wait_for_quiescent);
5886 	return handled;
5887 }
5888 
5889 static int handle_active_stripes(struct r5conf *conf, int group,
5890 				 struct r5worker *worker,
5891 				 struct list_head *temp_inactive_list)
5892 {
5893 	struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
5894 	int i, batch_size = 0, hash;
5895 	bool release_inactive = false;
5896 
5897 	while (batch_size < MAX_STRIPE_BATCH &&
5898 			(sh = __get_priority_stripe(conf, group)) != NULL)
5899 		batch[batch_size++] = sh;
5900 
5901 	if (batch_size == 0) {
5902 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5903 			if (!list_empty(temp_inactive_list + i))
5904 				break;
5905 		if (i == NR_STRIPE_HASH_LOCKS) {
5906 			spin_unlock_irq(&conf->device_lock);
5907 			r5l_flush_stripe_to_raid(conf->log);
5908 			spin_lock_irq(&conf->device_lock);
5909 			return batch_size;
5910 		}
5911 		release_inactive = true;
5912 	}
5913 	spin_unlock_irq(&conf->device_lock);
5914 
5915 	release_inactive_stripe_list(conf, temp_inactive_list,
5916 				     NR_STRIPE_HASH_LOCKS);
5917 
5918 	r5l_flush_stripe_to_raid(conf->log);
5919 	if (release_inactive) {
5920 		spin_lock_irq(&conf->device_lock);
5921 		return 0;
5922 	}
5923 
5924 	for (i = 0; i < batch_size; i++)
5925 		handle_stripe(batch[i]);
5926 	r5l_write_stripe_run(conf->log);
5927 
5928 	cond_resched();
5929 
5930 	spin_lock_irq(&conf->device_lock);
5931 	for (i = 0; i < batch_size; i++) {
5932 		hash = batch[i]->hash_lock_index;
5933 		__release_stripe(conf, batch[i], &temp_inactive_list[hash]);
5934 	}
5935 	return batch_size;
5936 }
5937 
5938 static void raid5_do_work(struct work_struct *work)
5939 {
5940 	struct r5worker *worker = container_of(work, struct r5worker, work);
5941 	struct r5worker_group *group = worker->group;
5942 	struct r5conf *conf = group->conf;
5943 	int group_id = group - conf->worker_groups;
5944 	int handled;
5945 	struct blk_plug plug;
5946 
5947 	pr_debug("+++ raid5worker active\n");
5948 
5949 	blk_start_plug(&plug);
5950 	handled = 0;
5951 	spin_lock_irq(&conf->device_lock);
5952 	while (1) {
5953 		int batch_size, released;
5954 
5955 		released = release_stripe_list(conf, worker->temp_inactive_list);
5956 
5957 		batch_size = handle_active_stripes(conf, group_id, worker,
5958 						   worker->temp_inactive_list);
5959 		worker->working = false;
5960 		if (!batch_size && !released)
5961 			break;
5962 		handled += batch_size;
5963 	}
5964 	pr_debug("%d stripes handled\n", handled);
5965 
5966 	spin_unlock_irq(&conf->device_lock);
5967 	blk_finish_plug(&plug);
5968 
5969 	pr_debug("--- raid5worker inactive\n");
5970 }
5971 
5972 /*
5973  * This is our raid5 kernel thread.
5974  *
5975  * We scan the hash table for stripes which can be handled now.
5976  * During the scan, completed stripes are saved for us by the interrupt
5977  * handler, so that they will not have to wait for our next wakeup.
5978  */
5979 static void raid5d(struct md_thread *thread)
5980 {
5981 	struct mddev *mddev = thread->mddev;
5982 	struct r5conf *conf = mddev->private;
5983 	int handled;
5984 	struct blk_plug plug;
5985 
5986 	pr_debug("+++ raid5d active\n");
5987 
5988 	md_check_recovery(mddev);
5989 
5990 	if (!bio_list_empty(&conf->return_bi) &&
5991 	    !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
5992 		struct bio_list tmp = BIO_EMPTY_LIST;
5993 		spin_lock_irq(&conf->device_lock);
5994 		if (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
5995 			bio_list_merge(&tmp, &conf->return_bi);
5996 			bio_list_init(&conf->return_bi);
5997 		}
5998 		spin_unlock_irq(&conf->device_lock);
5999 		return_io(&tmp);
6000 	}
6001 
6002 	blk_start_plug(&plug);
6003 	handled = 0;
6004 	spin_lock_irq(&conf->device_lock);
6005 	while (1) {
6006 		struct bio *bio;
6007 		int batch_size, released;
6008 
6009 		released = release_stripe_list(conf, conf->temp_inactive_list);
6010 		if (released)
6011 			clear_bit(R5_DID_ALLOC, &conf->cache_state);
6012 
6013 		if (
6014 		    !list_empty(&conf->bitmap_list)) {
6015 			/* Now is a good time to flush some bitmap updates */
6016 			conf->seq_flush++;
6017 			spin_unlock_irq(&conf->device_lock);
6018 			bitmap_unplug(mddev->bitmap);
6019 			spin_lock_irq(&conf->device_lock);
6020 			conf->seq_write = conf->seq_flush;
6021 			activate_bit_delay(conf, conf->temp_inactive_list);
6022 		}
6023 		raid5_activate_delayed(conf);
6024 
6025 		while ((bio = remove_bio_from_retry(conf))) {
6026 			int ok;
6027 			spin_unlock_irq(&conf->device_lock);
6028 			ok = retry_aligned_read(conf, bio);
6029 			spin_lock_irq(&conf->device_lock);
6030 			if (!ok)
6031 				break;
6032 			handled++;
6033 		}
6034 
6035 		batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
6036 						   conf->temp_inactive_list);
6037 		if (!batch_size && !released)
6038 			break;
6039 		handled += batch_size;
6040 
6041 		if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
6042 			spin_unlock_irq(&conf->device_lock);
6043 			md_check_recovery(mddev);
6044 			spin_lock_irq(&conf->device_lock);
6045 		}
6046 	}
6047 	pr_debug("%d stripes handled\n", handled);
6048 
6049 	spin_unlock_irq(&conf->device_lock);
6050 	if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
6051 	    mutex_trylock(&conf->cache_size_mutex)) {
6052 		grow_one_stripe(conf, __GFP_NOWARN);
6053 		/* Set flag even if allocation failed.  This helps
6054 		 * slow down allocation requests when mem is short
6055 		 */
6056 		set_bit(R5_DID_ALLOC, &conf->cache_state);
6057 		mutex_unlock(&conf->cache_size_mutex);
6058 	}
6059 
6060 	r5l_flush_stripe_to_raid(conf->log);
6061 
6062 	async_tx_issue_pending_all();
6063 	blk_finish_plug(&plug);
6064 
6065 	pr_debug("--- raid5d inactive\n");
6066 }
6067 
6068 static ssize_t
6069 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
6070 {
6071 	struct r5conf *conf;
6072 	int ret = 0;
6073 	spin_lock(&mddev->lock);
6074 	conf = mddev->private;
6075 	if (conf)
6076 		ret = sprintf(page, "%d\n", conf->min_nr_stripes);
6077 	spin_unlock(&mddev->lock);
6078 	return ret;
6079 }
6080 
6081 int
6082 raid5_set_cache_size(struct mddev *mddev, int size)
6083 {
6084 	struct r5conf *conf = mddev->private;
6085 	int err;
6086 
6087 	if (size <= 16 || size > 32768)
6088 		return -EINVAL;
6089 
6090 	conf->min_nr_stripes = size;
6091 	mutex_lock(&conf->cache_size_mutex);
6092 	while (size < conf->max_nr_stripes &&
6093 	       drop_one_stripe(conf))
6094 		;
6095 	mutex_unlock(&conf->cache_size_mutex);
6096 
6097 
6098 	err = md_allow_write(mddev);
6099 	if (err)
6100 		return err;
6101 
6102 	mutex_lock(&conf->cache_size_mutex);
6103 	while (size > conf->max_nr_stripes)
6104 		if (!grow_one_stripe(conf, GFP_KERNEL))
6105 			break;
6106 	mutex_unlock(&conf->cache_size_mutex);
6107 
6108 	return 0;
6109 }
6110 EXPORT_SYMBOL(raid5_set_cache_size);
6111 
6112 static ssize_t
6113 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6114 {
6115 	struct r5conf *conf;
6116 	unsigned long new;
6117 	int err;
6118 
6119 	if (len >= PAGE_SIZE)
6120 		return -EINVAL;
6121 	if (kstrtoul(page, 10, &new))
6122 		return -EINVAL;
6123 	err = mddev_lock(mddev);
6124 	if (err)
6125 		return err;
6126 	conf = mddev->private;
6127 	if (!conf)
6128 		err = -ENODEV;
6129 	else
6130 		err = raid5_set_cache_size(mddev, new);
6131 	mddev_unlock(mddev);
6132 
6133 	return err ?: len;
6134 }
6135 
6136 static struct md_sysfs_entry
6137 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6138 				raid5_show_stripe_cache_size,
6139 				raid5_store_stripe_cache_size);
6140 
6141 static ssize_t
6142 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6143 {
6144 	struct r5conf *conf = mddev->private;
6145 	if (conf)
6146 		return sprintf(page, "%d\n", conf->rmw_level);
6147 	else
6148 		return 0;
6149 }
6150 
6151 static ssize_t
6152 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6153 {
6154 	struct r5conf *conf = mddev->private;
6155 	unsigned long new;
6156 
6157 	if (!conf)
6158 		return -ENODEV;
6159 
6160 	if (len >= PAGE_SIZE)
6161 		return -EINVAL;
6162 
6163 	if (kstrtoul(page, 10, &new))
6164 		return -EINVAL;
6165 
6166 	if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6167 		return -EINVAL;
6168 
6169 	if (new != PARITY_DISABLE_RMW &&
6170 	    new != PARITY_ENABLE_RMW &&
6171 	    new != PARITY_PREFER_RMW)
6172 		return -EINVAL;
6173 
6174 	conf->rmw_level = new;
6175 	return len;
6176 }
6177 
6178 static struct md_sysfs_entry
6179 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
6180 			 raid5_show_rmw_level,
6181 			 raid5_store_rmw_level);
6182 
6183 
6184 static ssize_t
6185 raid5_show_preread_threshold(struct mddev *mddev, char *page)
6186 {
6187 	struct r5conf *conf;
6188 	int ret = 0;
6189 	spin_lock(&mddev->lock);
6190 	conf = mddev->private;
6191 	if (conf)
6192 		ret = sprintf(page, "%d\n", conf->bypass_threshold);
6193 	spin_unlock(&mddev->lock);
6194 	return ret;
6195 }
6196 
6197 static ssize_t
6198 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
6199 {
6200 	struct r5conf *conf;
6201 	unsigned long new;
6202 	int err;
6203 
6204 	if (len >= PAGE_SIZE)
6205 		return -EINVAL;
6206 	if (kstrtoul(page, 10, &new))
6207 		return -EINVAL;
6208 
6209 	err = mddev_lock(mddev);
6210 	if (err)
6211 		return err;
6212 	conf = mddev->private;
6213 	if (!conf)
6214 		err = -ENODEV;
6215 	else if (new > conf->min_nr_stripes)
6216 		err = -EINVAL;
6217 	else
6218 		conf->bypass_threshold = new;
6219 	mddev_unlock(mddev);
6220 	return err ?: len;
6221 }
6222 
6223 static struct md_sysfs_entry
6224 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6225 					S_IRUGO | S_IWUSR,
6226 					raid5_show_preread_threshold,
6227 					raid5_store_preread_threshold);
6228 
6229 static ssize_t
6230 raid5_show_skip_copy(struct mddev *mddev, char *page)
6231 {
6232 	struct r5conf *conf;
6233 	int ret = 0;
6234 	spin_lock(&mddev->lock);
6235 	conf = mddev->private;
6236 	if (conf)
6237 		ret = sprintf(page, "%d\n", conf->skip_copy);
6238 	spin_unlock(&mddev->lock);
6239 	return ret;
6240 }
6241 
6242 static ssize_t
6243 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6244 {
6245 	struct r5conf *conf;
6246 	unsigned long new;
6247 	int err;
6248 
6249 	if (len >= PAGE_SIZE)
6250 		return -EINVAL;
6251 	if (kstrtoul(page, 10, &new))
6252 		return -EINVAL;
6253 	new = !!new;
6254 
6255 	err = mddev_lock(mddev);
6256 	if (err)
6257 		return err;
6258 	conf = mddev->private;
6259 	if (!conf)
6260 		err = -ENODEV;
6261 	else if (new != conf->skip_copy) {
6262 		mddev_suspend(mddev);
6263 		conf->skip_copy = new;
6264 		if (new)
6265 			mddev->queue->backing_dev_info.capabilities |=
6266 				BDI_CAP_STABLE_WRITES;
6267 		else
6268 			mddev->queue->backing_dev_info.capabilities &=
6269 				~BDI_CAP_STABLE_WRITES;
6270 		mddev_resume(mddev);
6271 	}
6272 	mddev_unlock(mddev);
6273 	return err ?: len;
6274 }
6275 
6276 static struct md_sysfs_entry
6277 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6278 					raid5_show_skip_copy,
6279 					raid5_store_skip_copy);
6280 
6281 static ssize_t
6282 stripe_cache_active_show(struct mddev *mddev, char *page)
6283 {
6284 	struct r5conf *conf = mddev->private;
6285 	if (conf)
6286 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6287 	else
6288 		return 0;
6289 }
6290 
6291 static struct md_sysfs_entry
6292 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6293 
6294 static ssize_t
6295 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6296 {
6297 	struct r5conf *conf;
6298 	int ret = 0;
6299 	spin_lock(&mddev->lock);
6300 	conf = mddev->private;
6301 	if (conf)
6302 		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6303 	spin_unlock(&mddev->lock);
6304 	return ret;
6305 }
6306 
6307 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6308 			       int *group_cnt,
6309 			       int *worker_cnt_per_group,
6310 			       struct r5worker_group **worker_groups);
6311 static ssize_t
6312 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6313 {
6314 	struct r5conf *conf;
6315 	unsigned long new;
6316 	int err;
6317 	struct r5worker_group *new_groups, *old_groups;
6318 	int group_cnt, worker_cnt_per_group;
6319 
6320 	if (len >= PAGE_SIZE)
6321 		return -EINVAL;
6322 	if (kstrtoul(page, 10, &new))
6323 		return -EINVAL;
6324 
6325 	err = mddev_lock(mddev);
6326 	if (err)
6327 		return err;
6328 	conf = mddev->private;
6329 	if (!conf)
6330 		err = -ENODEV;
6331 	else if (new != conf->worker_cnt_per_group) {
6332 		mddev_suspend(mddev);
6333 
6334 		old_groups = conf->worker_groups;
6335 		if (old_groups)
6336 			flush_workqueue(raid5_wq);
6337 
6338 		err = alloc_thread_groups(conf, new,
6339 					  &group_cnt, &worker_cnt_per_group,
6340 					  &new_groups);
6341 		if (!err) {
6342 			spin_lock_irq(&conf->device_lock);
6343 			conf->group_cnt = group_cnt;
6344 			conf->worker_cnt_per_group = worker_cnt_per_group;
6345 			conf->worker_groups = new_groups;
6346 			spin_unlock_irq(&conf->device_lock);
6347 
6348 			if (old_groups)
6349 				kfree(old_groups[0].workers);
6350 			kfree(old_groups);
6351 		}
6352 		mddev_resume(mddev);
6353 	}
6354 	mddev_unlock(mddev);
6355 
6356 	return err ?: len;
6357 }
6358 
6359 static struct md_sysfs_entry
6360 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6361 				raid5_show_group_thread_cnt,
6362 				raid5_store_group_thread_cnt);
6363 
6364 static struct attribute *raid5_attrs[] =  {
6365 	&raid5_stripecache_size.attr,
6366 	&raid5_stripecache_active.attr,
6367 	&raid5_preread_bypass_threshold.attr,
6368 	&raid5_group_thread_cnt.attr,
6369 	&raid5_skip_copy.attr,
6370 	&raid5_rmw_level.attr,
6371 	&r5c_journal_mode.attr,
6372 	NULL,
6373 };
6374 static struct attribute_group raid5_attrs_group = {
6375 	.name = NULL,
6376 	.attrs = raid5_attrs,
6377 };
6378 
6379 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6380 			       int *group_cnt,
6381 			       int *worker_cnt_per_group,
6382 			       struct r5worker_group **worker_groups)
6383 {
6384 	int i, j, k;
6385 	ssize_t size;
6386 	struct r5worker *workers;
6387 
6388 	*worker_cnt_per_group = cnt;
6389 	if (cnt == 0) {
6390 		*group_cnt = 0;
6391 		*worker_groups = NULL;
6392 		return 0;
6393 	}
6394 	*group_cnt = num_possible_nodes();
6395 	size = sizeof(struct r5worker) * cnt;
6396 	workers = kzalloc(size * *group_cnt, GFP_NOIO);
6397 	*worker_groups = kzalloc(sizeof(struct r5worker_group) *
6398 				*group_cnt, GFP_NOIO);
6399 	if (!*worker_groups || !workers) {
6400 		kfree(workers);
6401 		kfree(*worker_groups);
6402 		return -ENOMEM;
6403 	}
6404 
6405 	for (i = 0; i < *group_cnt; i++) {
6406 		struct r5worker_group *group;
6407 
6408 		group = &(*worker_groups)[i];
6409 		INIT_LIST_HEAD(&group->handle_list);
6410 		group->conf = conf;
6411 		group->workers = workers + i * cnt;
6412 
6413 		for (j = 0; j < cnt; j++) {
6414 			struct r5worker *worker = group->workers + j;
6415 			worker->group = group;
6416 			INIT_WORK(&worker->work, raid5_do_work);
6417 
6418 			for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6419 				INIT_LIST_HEAD(worker->temp_inactive_list + k);
6420 		}
6421 	}
6422 
6423 	return 0;
6424 }
6425 
6426 static void free_thread_groups(struct r5conf *conf)
6427 {
6428 	if (conf->worker_groups)
6429 		kfree(conf->worker_groups[0].workers);
6430 	kfree(conf->worker_groups);
6431 	conf->worker_groups = NULL;
6432 }
6433 
6434 static sector_t
6435 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6436 {
6437 	struct r5conf *conf = mddev->private;
6438 
6439 	if (!sectors)
6440 		sectors = mddev->dev_sectors;
6441 	if (!raid_disks)
6442 		/* size is defined by the smallest of previous and new size */
6443 		raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6444 
6445 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
6446 	sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
6447 	return sectors * (raid_disks - conf->max_degraded);
6448 }
6449 
6450 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6451 {
6452 	safe_put_page(percpu->spare_page);
6453 	if (percpu->scribble)
6454 		flex_array_free(percpu->scribble);
6455 	percpu->spare_page = NULL;
6456 	percpu->scribble = NULL;
6457 }
6458 
6459 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6460 {
6461 	if (conf->level == 6 && !percpu->spare_page)
6462 		percpu->spare_page = alloc_page(GFP_KERNEL);
6463 	if (!percpu->scribble)
6464 		percpu->scribble = scribble_alloc(max(conf->raid_disks,
6465 						      conf->previous_raid_disks),
6466 						  max(conf->chunk_sectors,
6467 						      conf->prev_chunk_sectors)
6468 						   / STRIPE_SECTORS,
6469 						  GFP_KERNEL);
6470 
6471 	if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6472 		free_scratch_buffer(conf, percpu);
6473 		return -ENOMEM;
6474 	}
6475 
6476 	return 0;
6477 }
6478 
6479 static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
6480 {
6481 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6482 
6483 	free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6484 	return 0;
6485 }
6486 
6487 static void raid5_free_percpu(struct r5conf *conf)
6488 {
6489 	if (!conf->percpu)
6490 		return;
6491 
6492 	cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6493 	free_percpu(conf->percpu);
6494 }
6495 
6496 static void free_conf(struct r5conf *conf)
6497 {
6498 	int i;
6499 
6500 	if (conf->log)
6501 		r5l_exit_log(conf->log);
6502 	if (conf->shrinker.nr_deferred)
6503 		unregister_shrinker(&conf->shrinker);
6504 
6505 	free_thread_groups(conf);
6506 	shrink_stripes(conf);
6507 	raid5_free_percpu(conf);
6508 	for (i = 0; i < conf->pool_size; i++)
6509 		if (conf->disks[i].extra_page)
6510 			put_page(conf->disks[i].extra_page);
6511 	kfree(conf->disks);
6512 	kfree(conf->stripe_hashtbl);
6513 	kfree(conf);
6514 }
6515 
6516 static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
6517 {
6518 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6519 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6520 
6521 	if (alloc_scratch_buffer(conf, percpu)) {
6522 		pr_warn("%s: failed memory allocation for cpu%u\n",
6523 			__func__, cpu);
6524 		return -ENOMEM;
6525 	}
6526 	return 0;
6527 }
6528 
6529 static int raid5_alloc_percpu(struct r5conf *conf)
6530 {
6531 	int err = 0;
6532 
6533 	conf->percpu = alloc_percpu(struct raid5_percpu);
6534 	if (!conf->percpu)
6535 		return -ENOMEM;
6536 
6537 	err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6538 	if (!err) {
6539 		conf->scribble_disks = max(conf->raid_disks,
6540 			conf->previous_raid_disks);
6541 		conf->scribble_sectors = max(conf->chunk_sectors,
6542 			conf->prev_chunk_sectors);
6543 	}
6544 	return err;
6545 }
6546 
6547 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6548 				      struct shrink_control *sc)
6549 {
6550 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6551 	unsigned long ret = SHRINK_STOP;
6552 
6553 	if (mutex_trylock(&conf->cache_size_mutex)) {
6554 		ret= 0;
6555 		while (ret < sc->nr_to_scan &&
6556 		       conf->max_nr_stripes > conf->min_nr_stripes) {
6557 			if (drop_one_stripe(conf) == 0) {
6558 				ret = SHRINK_STOP;
6559 				break;
6560 			}
6561 			ret++;
6562 		}
6563 		mutex_unlock(&conf->cache_size_mutex);
6564 	}
6565 	return ret;
6566 }
6567 
6568 static unsigned long raid5_cache_count(struct shrinker *shrink,
6569 				       struct shrink_control *sc)
6570 {
6571 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6572 
6573 	if (conf->max_nr_stripes < conf->min_nr_stripes)
6574 		/* unlikely, but not impossible */
6575 		return 0;
6576 	return conf->max_nr_stripes - conf->min_nr_stripes;
6577 }
6578 
6579 static struct r5conf *setup_conf(struct mddev *mddev)
6580 {
6581 	struct r5conf *conf;
6582 	int raid_disk, memory, max_disks;
6583 	struct md_rdev *rdev;
6584 	struct disk_info *disk;
6585 	char pers_name[6];
6586 	int i;
6587 	int group_cnt, worker_cnt_per_group;
6588 	struct r5worker_group *new_group;
6589 
6590 	if (mddev->new_level != 5
6591 	    && mddev->new_level != 4
6592 	    && mddev->new_level != 6) {
6593 		pr_warn("md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6594 			mdname(mddev), mddev->new_level);
6595 		return ERR_PTR(-EIO);
6596 	}
6597 	if ((mddev->new_level == 5
6598 	     && !algorithm_valid_raid5(mddev->new_layout)) ||
6599 	    (mddev->new_level == 6
6600 	     && !algorithm_valid_raid6(mddev->new_layout))) {
6601 		pr_warn("md/raid:%s: layout %d not supported\n",
6602 			mdname(mddev), mddev->new_layout);
6603 		return ERR_PTR(-EIO);
6604 	}
6605 	if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6606 		pr_warn("md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6607 			mdname(mddev), mddev->raid_disks);
6608 		return ERR_PTR(-EINVAL);
6609 	}
6610 
6611 	if (!mddev->new_chunk_sectors ||
6612 	    (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6613 	    !is_power_of_2(mddev->new_chunk_sectors)) {
6614 		pr_warn("md/raid:%s: invalid chunk size %d\n",
6615 			mdname(mddev), mddev->new_chunk_sectors << 9);
6616 		return ERR_PTR(-EINVAL);
6617 	}
6618 
6619 	conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6620 	if (conf == NULL)
6621 		goto abort;
6622 	/* Don't enable multi-threading by default*/
6623 	if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6624 				 &new_group)) {
6625 		conf->group_cnt = group_cnt;
6626 		conf->worker_cnt_per_group = worker_cnt_per_group;
6627 		conf->worker_groups = new_group;
6628 	} else
6629 		goto abort;
6630 	spin_lock_init(&conf->device_lock);
6631 	seqcount_init(&conf->gen_lock);
6632 	mutex_init(&conf->cache_size_mutex);
6633 	init_waitqueue_head(&conf->wait_for_quiescent);
6634 	init_waitqueue_head(&conf->wait_for_stripe);
6635 	init_waitqueue_head(&conf->wait_for_overlap);
6636 	INIT_LIST_HEAD(&conf->handle_list);
6637 	INIT_LIST_HEAD(&conf->hold_list);
6638 	INIT_LIST_HEAD(&conf->delayed_list);
6639 	INIT_LIST_HEAD(&conf->bitmap_list);
6640 	bio_list_init(&conf->return_bi);
6641 	init_llist_head(&conf->released_stripes);
6642 	atomic_set(&conf->active_stripes, 0);
6643 	atomic_set(&conf->preread_active_stripes, 0);
6644 	atomic_set(&conf->active_aligned_reads, 0);
6645 	conf->bypass_threshold = BYPASS_THRESHOLD;
6646 	conf->recovery_disabled = mddev->recovery_disabled - 1;
6647 
6648 	conf->raid_disks = mddev->raid_disks;
6649 	if (mddev->reshape_position == MaxSector)
6650 		conf->previous_raid_disks = mddev->raid_disks;
6651 	else
6652 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6653 	max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6654 
6655 	conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6656 			      GFP_KERNEL);
6657 
6658 	if (!conf->disks)
6659 		goto abort;
6660 
6661 	for (i = 0; i < max_disks; i++) {
6662 		conf->disks[i].extra_page = alloc_page(GFP_KERNEL);
6663 		if (!conf->disks[i].extra_page)
6664 			goto abort;
6665 	}
6666 
6667 	conf->mddev = mddev;
6668 
6669 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6670 		goto abort;
6671 
6672 	/* We init hash_locks[0] separately to that it can be used
6673 	 * as the reference lock in the spin_lock_nest_lock() call
6674 	 * in lock_all_device_hash_locks_irq in order to convince
6675 	 * lockdep that we know what we are doing.
6676 	 */
6677 	spin_lock_init(conf->hash_locks);
6678 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6679 		spin_lock_init(conf->hash_locks + i);
6680 
6681 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6682 		INIT_LIST_HEAD(conf->inactive_list + i);
6683 
6684 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6685 		INIT_LIST_HEAD(conf->temp_inactive_list + i);
6686 
6687 	atomic_set(&conf->r5c_cached_full_stripes, 0);
6688 	INIT_LIST_HEAD(&conf->r5c_full_stripe_list);
6689 	atomic_set(&conf->r5c_cached_partial_stripes, 0);
6690 	INIT_LIST_HEAD(&conf->r5c_partial_stripe_list);
6691 
6692 	conf->level = mddev->new_level;
6693 	conf->chunk_sectors = mddev->new_chunk_sectors;
6694 	if (raid5_alloc_percpu(conf) != 0)
6695 		goto abort;
6696 
6697 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6698 
6699 	rdev_for_each(rdev, mddev) {
6700 		raid_disk = rdev->raid_disk;
6701 		if (raid_disk >= max_disks
6702 		    || raid_disk < 0 || test_bit(Journal, &rdev->flags))
6703 			continue;
6704 		disk = conf->disks + raid_disk;
6705 
6706 		if (test_bit(Replacement, &rdev->flags)) {
6707 			if (disk->replacement)
6708 				goto abort;
6709 			disk->replacement = rdev;
6710 		} else {
6711 			if (disk->rdev)
6712 				goto abort;
6713 			disk->rdev = rdev;
6714 		}
6715 
6716 		if (test_bit(In_sync, &rdev->flags)) {
6717 			char b[BDEVNAME_SIZE];
6718 			pr_info("md/raid:%s: device %s operational as raid disk %d\n",
6719 				mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
6720 		} else if (rdev->saved_raid_disk != raid_disk)
6721 			/* Cannot rely on bitmap to complete recovery */
6722 			conf->fullsync = 1;
6723 	}
6724 
6725 	conf->level = mddev->new_level;
6726 	if (conf->level == 6) {
6727 		conf->max_degraded = 2;
6728 		if (raid6_call.xor_syndrome)
6729 			conf->rmw_level = PARITY_ENABLE_RMW;
6730 		else
6731 			conf->rmw_level = PARITY_DISABLE_RMW;
6732 	} else {
6733 		conf->max_degraded = 1;
6734 		conf->rmw_level = PARITY_ENABLE_RMW;
6735 	}
6736 	conf->algorithm = mddev->new_layout;
6737 	conf->reshape_progress = mddev->reshape_position;
6738 	if (conf->reshape_progress != MaxSector) {
6739 		conf->prev_chunk_sectors = mddev->chunk_sectors;
6740 		conf->prev_algo = mddev->layout;
6741 	} else {
6742 		conf->prev_chunk_sectors = conf->chunk_sectors;
6743 		conf->prev_algo = conf->algorithm;
6744 	}
6745 
6746 	conf->min_nr_stripes = NR_STRIPES;
6747 	if (mddev->reshape_position != MaxSector) {
6748 		int stripes = max_t(int,
6749 			((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4,
6750 			((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4);
6751 		conf->min_nr_stripes = max(NR_STRIPES, stripes);
6752 		if (conf->min_nr_stripes != NR_STRIPES)
6753 			pr_info("md/raid:%s: force stripe size %d for reshape\n",
6754 				mdname(mddev), conf->min_nr_stripes);
6755 	}
6756 	memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
6757 		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
6758 	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
6759 	if (grow_stripes(conf, conf->min_nr_stripes)) {
6760 		pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
6761 			mdname(mddev), memory);
6762 		goto abort;
6763 	} else
6764 		pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
6765 	/*
6766 	 * Losing a stripe head costs more than the time to refill it,
6767 	 * it reduces the queue depth and so can hurt throughput.
6768 	 * So set it rather large, scaled by number of devices.
6769 	 */
6770 	conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
6771 	conf->shrinker.scan_objects = raid5_cache_scan;
6772 	conf->shrinker.count_objects = raid5_cache_count;
6773 	conf->shrinker.batch = 128;
6774 	conf->shrinker.flags = 0;
6775 	if (register_shrinker(&conf->shrinker)) {
6776 		pr_warn("md/raid:%s: couldn't register shrinker.\n",
6777 			mdname(mddev));
6778 		goto abort;
6779 	}
6780 
6781 	sprintf(pers_name, "raid%d", mddev->new_level);
6782 	conf->thread = md_register_thread(raid5d, mddev, pers_name);
6783 	if (!conf->thread) {
6784 		pr_warn("md/raid:%s: couldn't allocate thread.\n",
6785 			mdname(mddev));
6786 		goto abort;
6787 	}
6788 
6789 	return conf;
6790 
6791  abort:
6792 	if (conf) {
6793 		free_conf(conf);
6794 		return ERR_PTR(-EIO);
6795 	} else
6796 		return ERR_PTR(-ENOMEM);
6797 }
6798 
6799 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
6800 {
6801 	switch (algo) {
6802 	case ALGORITHM_PARITY_0:
6803 		if (raid_disk < max_degraded)
6804 			return 1;
6805 		break;
6806 	case ALGORITHM_PARITY_N:
6807 		if (raid_disk >= raid_disks - max_degraded)
6808 			return 1;
6809 		break;
6810 	case ALGORITHM_PARITY_0_6:
6811 		if (raid_disk == 0 ||
6812 		    raid_disk == raid_disks - 1)
6813 			return 1;
6814 		break;
6815 	case ALGORITHM_LEFT_ASYMMETRIC_6:
6816 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
6817 	case ALGORITHM_LEFT_SYMMETRIC_6:
6818 	case ALGORITHM_RIGHT_SYMMETRIC_6:
6819 		if (raid_disk == raid_disks - 1)
6820 			return 1;
6821 	}
6822 	return 0;
6823 }
6824 
6825 static int raid5_run(struct mddev *mddev)
6826 {
6827 	struct r5conf *conf;
6828 	int working_disks = 0;
6829 	int dirty_parity_disks = 0;
6830 	struct md_rdev *rdev;
6831 	struct md_rdev *journal_dev = NULL;
6832 	sector_t reshape_offset = 0;
6833 	int i;
6834 	long long min_offset_diff = 0;
6835 	int first = 1;
6836 
6837 	if (mddev->recovery_cp != MaxSector)
6838 		pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
6839 			  mdname(mddev));
6840 
6841 	rdev_for_each(rdev, mddev) {
6842 		long long diff;
6843 
6844 		if (test_bit(Journal, &rdev->flags)) {
6845 			journal_dev = rdev;
6846 			continue;
6847 		}
6848 		if (rdev->raid_disk < 0)
6849 			continue;
6850 		diff = (rdev->new_data_offset - rdev->data_offset);
6851 		if (first) {
6852 			min_offset_diff = diff;
6853 			first = 0;
6854 		} else if (mddev->reshape_backwards &&
6855 			 diff < min_offset_diff)
6856 			min_offset_diff = diff;
6857 		else if (!mddev->reshape_backwards &&
6858 			 diff > min_offset_diff)
6859 			min_offset_diff = diff;
6860 	}
6861 
6862 	if (mddev->reshape_position != MaxSector) {
6863 		/* Check that we can continue the reshape.
6864 		 * Difficulties arise if the stripe we would write to
6865 		 * next is at or after the stripe we would read from next.
6866 		 * For a reshape that changes the number of devices, this
6867 		 * is only possible for a very short time, and mdadm makes
6868 		 * sure that time appears to have past before assembling
6869 		 * the array.  So we fail if that time hasn't passed.
6870 		 * For a reshape that keeps the number of devices the same
6871 		 * mdadm must be monitoring the reshape can keeping the
6872 		 * critical areas read-only and backed up.  It will start
6873 		 * the array in read-only mode, so we check for that.
6874 		 */
6875 		sector_t here_new, here_old;
6876 		int old_disks;
6877 		int max_degraded = (mddev->level == 6 ? 2 : 1);
6878 		int chunk_sectors;
6879 		int new_data_disks;
6880 
6881 		if (journal_dev) {
6882 			pr_warn("md/raid:%s: don't support reshape with journal - aborting.\n",
6883 				mdname(mddev));
6884 			return -EINVAL;
6885 		}
6886 
6887 		if (mddev->new_level != mddev->level) {
6888 			pr_warn("md/raid:%s: unsupported reshape required - aborting.\n",
6889 				mdname(mddev));
6890 			return -EINVAL;
6891 		}
6892 		old_disks = mddev->raid_disks - mddev->delta_disks;
6893 		/* reshape_position must be on a new-stripe boundary, and one
6894 		 * further up in new geometry must map after here in old
6895 		 * geometry.
6896 		 * If the chunk sizes are different, then as we perform reshape
6897 		 * in units of the largest of the two, reshape_position needs
6898 		 * be a multiple of the largest chunk size times new data disks.
6899 		 */
6900 		here_new = mddev->reshape_position;
6901 		chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
6902 		new_data_disks = mddev->raid_disks - max_degraded;
6903 		if (sector_div(here_new, chunk_sectors * new_data_disks)) {
6904 			pr_warn("md/raid:%s: reshape_position not on a stripe boundary\n",
6905 				mdname(mddev));
6906 			return -EINVAL;
6907 		}
6908 		reshape_offset = here_new * chunk_sectors;
6909 		/* here_new is the stripe we will write to */
6910 		here_old = mddev->reshape_position;
6911 		sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
6912 		/* here_old is the first stripe that we might need to read
6913 		 * from */
6914 		if (mddev->delta_disks == 0) {
6915 			/* We cannot be sure it is safe to start an in-place
6916 			 * reshape.  It is only safe if user-space is monitoring
6917 			 * and taking constant backups.
6918 			 * mdadm always starts a situation like this in
6919 			 * readonly mode so it can take control before
6920 			 * allowing any writes.  So just check for that.
6921 			 */
6922 			if (abs(min_offset_diff) >= mddev->chunk_sectors &&
6923 			    abs(min_offset_diff) >= mddev->new_chunk_sectors)
6924 				/* not really in-place - so OK */;
6925 			else if (mddev->ro == 0) {
6926 				pr_warn("md/raid:%s: in-place reshape must be started in read-only mode - aborting\n",
6927 					mdname(mddev));
6928 				return -EINVAL;
6929 			}
6930 		} else if (mddev->reshape_backwards
6931 		    ? (here_new * chunk_sectors + min_offset_diff <=
6932 		       here_old * chunk_sectors)
6933 		    : (here_new * chunk_sectors >=
6934 		       here_old * chunk_sectors + (-min_offset_diff))) {
6935 			/* Reading from the same stripe as writing to - bad */
6936 			pr_warn("md/raid:%s: reshape_position too early for auto-recovery - aborting.\n",
6937 				mdname(mddev));
6938 			return -EINVAL;
6939 		}
6940 		pr_debug("md/raid:%s: reshape will continue\n", mdname(mddev));
6941 		/* OK, we should be able to continue; */
6942 	} else {
6943 		BUG_ON(mddev->level != mddev->new_level);
6944 		BUG_ON(mddev->layout != mddev->new_layout);
6945 		BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
6946 		BUG_ON(mddev->delta_disks != 0);
6947 	}
6948 
6949 	if (mddev->private == NULL)
6950 		conf = setup_conf(mddev);
6951 	else
6952 		conf = mddev->private;
6953 
6954 	if (IS_ERR(conf))
6955 		return PTR_ERR(conf);
6956 
6957 	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
6958 		if (!journal_dev) {
6959 			pr_warn("md/raid:%s: journal disk is missing, force array readonly\n",
6960 				mdname(mddev));
6961 			mddev->ro = 1;
6962 			set_disk_ro(mddev->gendisk, 1);
6963 		} else if (mddev->recovery_cp == MaxSector)
6964 			set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
6965 	}
6966 
6967 	conf->min_offset_diff = min_offset_diff;
6968 	mddev->thread = conf->thread;
6969 	conf->thread = NULL;
6970 	mddev->private = conf;
6971 
6972 	for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
6973 	     i++) {
6974 		rdev = conf->disks[i].rdev;
6975 		if (!rdev && conf->disks[i].replacement) {
6976 			/* The replacement is all we have yet */
6977 			rdev = conf->disks[i].replacement;
6978 			conf->disks[i].replacement = NULL;
6979 			clear_bit(Replacement, &rdev->flags);
6980 			conf->disks[i].rdev = rdev;
6981 		}
6982 		if (!rdev)
6983 			continue;
6984 		if (conf->disks[i].replacement &&
6985 		    conf->reshape_progress != MaxSector) {
6986 			/* replacements and reshape simply do not mix. */
6987 			pr_warn("md: cannot handle concurrent replacement and reshape.\n");
6988 			goto abort;
6989 		}
6990 		if (test_bit(In_sync, &rdev->flags)) {
6991 			working_disks++;
6992 			continue;
6993 		}
6994 		/* This disc is not fully in-sync.  However if it
6995 		 * just stored parity (beyond the recovery_offset),
6996 		 * when we don't need to be concerned about the
6997 		 * array being dirty.
6998 		 * When reshape goes 'backwards', we never have
6999 		 * partially completed devices, so we only need
7000 		 * to worry about reshape going forwards.
7001 		 */
7002 		/* Hack because v0.91 doesn't store recovery_offset properly. */
7003 		if (mddev->major_version == 0 &&
7004 		    mddev->minor_version > 90)
7005 			rdev->recovery_offset = reshape_offset;
7006 
7007 		if (rdev->recovery_offset < reshape_offset) {
7008 			/* We need to check old and new layout */
7009 			if (!only_parity(rdev->raid_disk,
7010 					 conf->algorithm,
7011 					 conf->raid_disks,
7012 					 conf->max_degraded))
7013 				continue;
7014 		}
7015 		if (!only_parity(rdev->raid_disk,
7016 				 conf->prev_algo,
7017 				 conf->previous_raid_disks,
7018 				 conf->max_degraded))
7019 			continue;
7020 		dirty_parity_disks++;
7021 	}
7022 
7023 	/*
7024 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
7025 	 */
7026 	mddev->degraded = calc_degraded(conf);
7027 
7028 	if (has_failed(conf)) {
7029 		pr_crit("md/raid:%s: not enough operational devices (%d/%d failed)\n",
7030 			mdname(mddev), mddev->degraded, conf->raid_disks);
7031 		goto abort;
7032 	}
7033 
7034 	/* device size must be a multiple of chunk size */
7035 	mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
7036 	mddev->resync_max_sectors = mddev->dev_sectors;
7037 
7038 	if (mddev->degraded > dirty_parity_disks &&
7039 	    mddev->recovery_cp != MaxSector) {
7040 		if (mddev->ok_start_degraded)
7041 			pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
7042 				mdname(mddev));
7043 		else {
7044 			pr_crit("md/raid:%s: cannot start dirty degraded array.\n",
7045 				mdname(mddev));
7046 			goto abort;
7047 		}
7048 	}
7049 
7050 	pr_info("md/raid:%s: raid level %d active with %d out of %d devices, algorithm %d\n",
7051 		mdname(mddev), conf->level,
7052 		mddev->raid_disks-mddev->degraded, mddev->raid_disks,
7053 		mddev->new_layout);
7054 
7055 	print_raid5_conf(conf);
7056 
7057 	if (conf->reshape_progress != MaxSector) {
7058 		conf->reshape_safe = conf->reshape_progress;
7059 		atomic_set(&conf->reshape_stripes, 0);
7060 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7061 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7062 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7063 		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7064 		mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7065 							"reshape");
7066 	}
7067 
7068 	/* Ok, everything is just fine now */
7069 	if (mddev->to_remove == &raid5_attrs_group)
7070 		mddev->to_remove = NULL;
7071 	else if (mddev->kobj.sd &&
7072 	    sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
7073 		pr_warn("raid5: failed to create sysfs attributes for %s\n",
7074 			mdname(mddev));
7075 	md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7076 
7077 	if (mddev->queue) {
7078 		int chunk_size;
7079 		bool discard_supported = true;
7080 		/* read-ahead size must cover two whole stripes, which
7081 		 * is 2 * (datadisks) * chunksize where 'n' is the
7082 		 * number of raid devices
7083 		 */
7084 		int data_disks = conf->previous_raid_disks - conf->max_degraded;
7085 		int stripe = data_disks *
7086 			((mddev->chunk_sectors << 9) / PAGE_SIZE);
7087 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
7088 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
7089 
7090 		chunk_size = mddev->chunk_sectors << 9;
7091 		blk_queue_io_min(mddev->queue, chunk_size);
7092 		blk_queue_io_opt(mddev->queue, chunk_size *
7093 				 (conf->raid_disks - conf->max_degraded));
7094 		mddev->queue->limits.raid_partial_stripes_expensive = 1;
7095 		/*
7096 		 * We can only discard a whole stripe. It doesn't make sense to
7097 		 * discard data disk but write parity disk
7098 		 */
7099 		stripe = stripe * PAGE_SIZE;
7100 		/* Round up to power of 2, as discard handling
7101 		 * currently assumes that */
7102 		while ((stripe-1) & stripe)
7103 			stripe = (stripe | (stripe-1)) + 1;
7104 		mddev->queue->limits.discard_alignment = stripe;
7105 		mddev->queue->limits.discard_granularity = stripe;
7106 
7107 		/*
7108 		 * We use 16-bit counter of active stripes in bi_phys_segments
7109 		 * (minus one for over-loaded initialization)
7110 		 */
7111 		blk_queue_max_hw_sectors(mddev->queue, 0xfffe * STRIPE_SECTORS);
7112 		blk_queue_max_discard_sectors(mddev->queue,
7113 					      0xfffe * STRIPE_SECTORS);
7114 
7115 		/*
7116 		 * unaligned part of discard request will be ignored, so can't
7117 		 * guarantee discard_zeroes_data
7118 		 */
7119 		mddev->queue->limits.discard_zeroes_data = 0;
7120 
7121 		blk_queue_max_write_same_sectors(mddev->queue, 0);
7122 
7123 		rdev_for_each(rdev, mddev) {
7124 			disk_stack_limits(mddev->gendisk, rdev->bdev,
7125 					  rdev->data_offset << 9);
7126 			disk_stack_limits(mddev->gendisk, rdev->bdev,
7127 					  rdev->new_data_offset << 9);
7128 			/*
7129 			 * discard_zeroes_data is required, otherwise data
7130 			 * could be lost. Consider a scenario: discard a stripe
7131 			 * (the stripe could be inconsistent if
7132 			 * discard_zeroes_data is 0); write one disk of the
7133 			 * stripe (the stripe could be inconsistent again
7134 			 * depending on which disks are used to calculate
7135 			 * parity); the disk is broken; The stripe data of this
7136 			 * disk is lost.
7137 			 */
7138 			if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
7139 			    !bdev_get_queue(rdev->bdev)->
7140 						limits.discard_zeroes_data)
7141 				discard_supported = false;
7142 			/* Unfortunately, discard_zeroes_data is not currently
7143 			 * a guarantee - just a hint.  So we only allow DISCARD
7144 			 * if the sysadmin has confirmed that only safe devices
7145 			 * are in use by setting a module parameter.
7146 			 */
7147 			if (!devices_handle_discard_safely) {
7148 				if (discard_supported) {
7149 					pr_info("md/raid456: discard support disabled due to uncertainty.\n");
7150 					pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
7151 				}
7152 				discard_supported = false;
7153 			}
7154 		}
7155 
7156 		if (discard_supported &&
7157 		    mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
7158 		    mddev->queue->limits.discard_granularity >= stripe)
7159 			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
7160 						mddev->queue);
7161 		else
7162 			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
7163 						mddev->queue);
7164 
7165 		blk_queue_max_hw_sectors(mddev->queue, UINT_MAX);
7166 	}
7167 
7168 	if (journal_dev) {
7169 		char b[BDEVNAME_SIZE];
7170 
7171 		pr_debug("md/raid:%s: using device %s as journal\n",
7172 			 mdname(mddev), bdevname(journal_dev->bdev, b));
7173 		if (r5l_init_log(conf, journal_dev))
7174 			goto abort;
7175 	}
7176 
7177 	return 0;
7178 abort:
7179 	md_unregister_thread(&mddev->thread);
7180 	print_raid5_conf(conf);
7181 	free_conf(conf);
7182 	mddev->private = NULL;
7183 	pr_warn("md/raid:%s: failed to run raid set.\n", mdname(mddev));
7184 	return -EIO;
7185 }
7186 
7187 static void raid5_free(struct mddev *mddev, void *priv)
7188 {
7189 	struct r5conf *conf = priv;
7190 
7191 	free_conf(conf);
7192 	mddev->to_remove = &raid5_attrs_group;
7193 }
7194 
7195 static void raid5_status(struct seq_file *seq, struct mddev *mddev)
7196 {
7197 	struct r5conf *conf = mddev->private;
7198 	int i;
7199 
7200 	seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
7201 		conf->chunk_sectors / 2, mddev->layout);
7202 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
7203 	rcu_read_lock();
7204 	for (i = 0; i < conf->raid_disks; i++) {
7205 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
7206 		seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
7207 	}
7208 	rcu_read_unlock();
7209 	seq_printf (seq, "]");
7210 }
7211 
7212 static void print_raid5_conf (struct r5conf *conf)
7213 {
7214 	int i;
7215 	struct disk_info *tmp;
7216 
7217 	pr_debug("RAID conf printout:\n");
7218 	if (!conf) {
7219 		pr_debug("(conf==NULL)\n");
7220 		return;
7221 	}
7222 	pr_debug(" --- level:%d rd:%d wd:%d\n", conf->level,
7223 	       conf->raid_disks,
7224 	       conf->raid_disks - conf->mddev->degraded);
7225 
7226 	for (i = 0; i < conf->raid_disks; i++) {
7227 		char b[BDEVNAME_SIZE];
7228 		tmp = conf->disks + i;
7229 		if (tmp->rdev)
7230 			pr_debug(" disk %d, o:%d, dev:%s\n",
7231 			       i, !test_bit(Faulty, &tmp->rdev->flags),
7232 			       bdevname(tmp->rdev->bdev, b));
7233 	}
7234 }
7235 
7236 static int raid5_spare_active(struct mddev *mddev)
7237 {
7238 	int i;
7239 	struct r5conf *conf = mddev->private;
7240 	struct disk_info *tmp;
7241 	int count = 0;
7242 	unsigned long flags;
7243 
7244 	for (i = 0; i < conf->raid_disks; i++) {
7245 		tmp = conf->disks + i;
7246 		if (tmp->replacement
7247 		    && tmp->replacement->recovery_offset == MaxSector
7248 		    && !test_bit(Faulty, &tmp->replacement->flags)
7249 		    && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7250 			/* Replacement has just become active. */
7251 			if (!tmp->rdev
7252 			    || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7253 				count++;
7254 			if (tmp->rdev) {
7255 				/* Replaced device not technically faulty,
7256 				 * but we need to be sure it gets removed
7257 				 * and never re-added.
7258 				 */
7259 				set_bit(Faulty, &tmp->rdev->flags);
7260 				sysfs_notify_dirent_safe(
7261 					tmp->rdev->sysfs_state);
7262 			}
7263 			sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7264 		} else if (tmp->rdev
7265 		    && tmp->rdev->recovery_offset == MaxSector
7266 		    && !test_bit(Faulty, &tmp->rdev->flags)
7267 		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7268 			count++;
7269 			sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7270 		}
7271 	}
7272 	spin_lock_irqsave(&conf->device_lock, flags);
7273 	mddev->degraded = calc_degraded(conf);
7274 	spin_unlock_irqrestore(&conf->device_lock, flags);
7275 	print_raid5_conf(conf);
7276 	return count;
7277 }
7278 
7279 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7280 {
7281 	struct r5conf *conf = mddev->private;
7282 	int err = 0;
7283 	int number = rdev->raid_disk;
7284 	struct md_rdev **rdevp;
7285 	struct disk_info *p = conf->disks + number;
7286 
7287 	print_raid5_conf(conf);
7288 	if (test_bit(Journal, &rdev->flags) && conf->log) {
7289 		struct r5l_log *log;
7290 		/*
7291 		 * we can't wait pending write here, as this is called in
7292 		 * raid5d, wait will deadlock.
7293 		 */
7294 		if (atomic_read(&mddev->writes_pending))
7295 			return -EBUSY;
7296 		log = conf->log;
7297 		conf->log = NULL;
7298 		synchronize_rcu();
7299 		r5l_exit_log(log);
7300 		return 0;
7301 	}
7302 	if (rdev == p->rdev)
7303 		rdevp = &p->rdev;
7304 	else if (rdev == p->replacement)
7305 		rdevp = &p->replacement;
7306 	else
7307 		return 0;
7308 
7309 	if (number >= conf->raid_disks &&
7310 	    conf->reshape_progress == MaxSector)
7311 		clear_bit(In_sync, &rdev->flags);
7312 
7313 	if (test_bit(In_sync, &rdev->flags) ||
7314 	    atomic_read(&rdev->nr_pending)) {
7315 		err = -EBUSY;
7316 		goto abort;
7317 	}
7318 	/* Only remove non-faulty devices if recovery
7319 	 * isn't possible.
7320 	 */
7321 	if (!test_bit(Faulty, &rdev->flags) &&
7322 	    mddev->recovery_disabled != conf->recovery_disabled &&
7323 	    !has_failed(conf) &&
7324 	    (!p->replacement || p->replacement == rdev) &&
7325 	    number < conf->raid_disks) {
7326 		err = -EBUSY;
7327 		goto abort;
7328 	}
7329 	*rdevp = NULL;
7330 	if (!test_bit(RemoveSynchronized, &rdev->flags)) {
7331 		synchronize_rcu();
7332 		if (atomic_read(&rdev->nr_pending)) {
7333 			/* lost the race, try later */
7334 			err = -EBUSY;
7335 			*rdevp = rdev;
7336 		}
7337 	}
7338 	if (p->replacement) {
7339 		/* We must have just cleared 'rdev' */
7340 		p->rdev = p->replacement;
7341 		clear_bit(Replacement, &p->replacement->flags);
7342 		smp_mb(); /* Make sure other CPUs may see both as identical
7343 			   * but will never see neither - if they are careful
7344 			   */
7345 		p->replacement = NULL;
7346 		clear_bit(WantReplacement, &rdev->flags);
7347 	} else
7348 		/* We might have just removed the Replacement as faulty-
7349 		 * clear the bit just in case
7350 		 */
7351 		clear_bit(WantReplacement, &rdev->flags);
7352 abort:
7353 
7354 	print_raid5_conf(conf);
7355 	return err;
7356 }
7357 
7358 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7359 {
7360 	struct r5conf *conf = mddev->private;
7361 	int err = -EEXIST;
7362 	int disk;
7363 	struct disk_info *p;
7364 	int first = 0;
7365 	int last = conf->raid_disks - 1;
7366 
7367 	if (test_bit(Journal, &rdev->flags)) {
7368 		char b[BDEVNAME_SIZE];
7369 		if (conf->log)
7370 			return -EBUSY;
7371 
7372 		rdev->raid_disk = 0;
7373 		/*
7374 		 * The array is in readonly mode if journal is missing, so no
7375 		 * write requests running. We should be safe
7376 		 */
7377 		r5l_init_log(conf, rdev);
7378 		pr_debug("md/raid:%s: using device %s as journal\n",
7379 			 mdname(mddev), bdevname(rdev->bdev, b));
7380 		return 0;
7381 	}
7382 	if (mddev->recovery_disabled == conf->recovery_disabled)
7383 		return -EBUSY;
7384 
7385 	if (rdev->saved_raid_disk < 0 && has_failed(conf))
7386 		/* no point adding a device */
7387 		return -EINVAL;
7388 
7389 	if (rdev->raid_disk >= 0)
7390 		first = last = rdev->raid_disk;
7391 
7392 	/*
7393 	 * find the disk ... but prefer rdev->saved_raid_disk
7394 	 * if possible.
7395 	 */
7396 	if (rdev->saved_raid_disk >= 0 &&
7397 	    rdev->saved_raid_disk >= first &&
7398 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
7399 		first = rdev->saved_raid_disk;
7400 
7401 	for (disk = first; disk <= last; disk++) {
7402 		p = conf->disks + disk;
7403 		if (p->rdev == NULL) {
7404 			clear_bit(In_sync, &rdev->flags);
7405 			rdev->raid_disk = disk;
7406 			err = 0;
7407 			if (rdev->saved_raid_disk != disk)
7408 				conf->fullsync = 1;
7409 			rcu_assign_pointer(p->rdev, rdev);
7410 			goto out;
7411 		}
7412 	}
7413 	for (disk = first; disk <= last; disk++) {
7414 		p = conf->disks + disk;
7415 		if (test_bit(WantReplacement, &p->rdev->flags) &&
7416 		    p->replacement == NULL) {
7417 			clear_bit(In_sync, &rdev->flags);
7418 			set_bit(Replacement, &rdev->flags);
7419 			rdev->raid_disk = disk;
7420 			err = 0;
7421 			conf->fullsync = 1;
7422 			rcu_assign_pointer(p->replacement, rdev);
7423 			break;
7424 		}
7425 	}
7426 out:
7427 	print_raid5_conf(conf);
7428 	return err;
7429 }
7430 
7431 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7432 {
7433 	/* no resync is happening, and there is enough space
7434 	 * on all devices, so we can resize.
7435 	 * We need to make sure resync covers any new space.
7436 	 * If the array is shrinking we should possibly wait until
7437 	 * any io in the removed space completes, but it hardly seems
7438 	 * worth it.
7439 	 */
7440 	sector_t newsize;
7441 	struct r5conf *conf = mddev->private;
7442 
7443 	if (conf->log)
7444 		return -EINVAL;
7445 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
7446 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7447 	if (mddev->external_size &&
7448 	    mddev->array_sectors > newsize)
7449 		return -EINVAL;
7450 	if (mddev->bitmap) {
7451 		int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7452 		if (ret)
7453 			return ret;
7454 	}
7455 	md_set_array_sectors(mddev, newsize);
7456 	set_capacity(mddev->gendisk, mddev->array_sectors);
7457 	revalidate_disk(mddev->gendisk);
7458 	if (sectors > mddev->dev_sectors &&
7459 	    mddev->recovery_cp > mddev->dev_sectors) {
7460 		mddev->recovery_cp = mddev->dev_sectors;
7461 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7462 	}
7463 	mddev->dev_sectors = sectors;
7464 	mddev->resync_max_sectors = sectors;
7465 	return 0;
7466 }
7467 
7468 static int check_stripe_cache(struct mddev *mddev)
7469 {
7470 	/* Can only proceed if there are plenty of stripe_heads.
7471 	 * We need a minimum of one full stripe,, and for sensible progress
7472 	 * it is best to have about 4 times that.
7473 	 * If we require 4 times, then the default 256 4K stripe_heads will
7474 	 * allow for chunk sizes up to 256K, which is probably OK.
7475 	 * If the chunk size is greater, user-space should request more
7476 	 * stripe_heads first.
7477 	 */
7478 	struct r5conf *conf = mddev->private;
7479 	if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7480 	    > conf->min_nr_stripes ||
7481 	    ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7482 	    > conf->min_nr_stripes) {
7483 		pr_warn("md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7484 			mdname(mddev),
7485 			((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7486 			 / STRIPE_SIZE)*4);
7487 		return 0;
7488 	}
7489 	return 1;
7490 }
7491 
7492 static int check_reshape(struct mddev *mddev)
7493 {
7494 	struct r5conf *conf = mddev->private;
7495 
7496 	if (conf->log)
7497 		return -EINVAL;
7498 	if (mddev->delta_disks == 0 &&
7499 	    mddev->new_layout == mddev->layout &&
7500 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
7501 		return 0; /* nothing to do */
7502 	if (has_failed(conf))
7503 		return -EINVAL;
7504 	if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7505 		/* We might be able to shrink, but the devices must
7506 		 * be made bigger first.
7507 		 * For raid6, 4 is the minimum size.
7508 		 * Otherwise 2 is the minimum
7509 		 */
7510 		int min = 2;
7511 		if (mddev->level == 6)
7512 			min = 4;
7513 		if (mddev->raid_disks + mddev->delta_disks < min)
7514 			return -EINVAL;
7515 	}
7516 
7517 	if (!check_stripe_cache(mddev))
7518 		return -ENOSPC;
7519 
7520 	if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7521 	    mddev->delta_disks > 0)
7522 		if (resize_chunks(conf,
7523 				  conf->previous_raid_disks
7524 				  + max(0, mddev->delta_disks),
7525 				  max(mddev->new_chunk_sectors,
7526 				      mddev->chunk_sectors)
7527 			    ) < 0)
7528 			return -ENOMEM;
7529 	return resize_stripes(conf, (conf->previous_raid_disks
7530 				     + mddev->delta_disks));
7531 }
7532 
7533 static int raid5_start_reshape(struct mddev *mddev)
7534 {
7535 	struct r5conf *conf = mddev->private;
7536 	struct md_rdev *rdev;
7537 	int spares = 0;
7538 	unsigned long flags;
7539 
7540 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7541 		return -EBUSY;
7542 
7543 	if (!check_stripe_cache(mddev))
7544 		return -ENOSPC;
7545 
7546 	if (has_failed(conf))
7547 		return -EINVAL;
7548 
7549 	rdev_for_each(rdev, mddev) {
7550 		if (!test_bit(In_sync, &rdev->flags)
7551 		    && !test_bit(Faulty, &rdev->flags))
7552 			spares++;
7553 	}
7554 
7555 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7556 		/* Not enough devices even to make a degraded array
7557 		 * of that size
7558 		 */
7559 		return -EINVAL;
7560 
7561 	/* Refuse to reduce size of the array.  Any reductions in
7562 	 * array size must be through explicit setting of array_size
7563 	 * attribute.
7564 	 */
7565 	if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7566 	    < mddev->array_sectors) {
7567 		pr_warn("md/raid:%s: array size must be reduced before number of disks\n",
7568 			mdname(mddev));
7569 		return -EINVAL;
7570 	}
7571 
7572 	atomic_set(&conf->reshape_stripes, 0);
7573 	spin_lock_irq(&conf->device_lock);
7574 	write_seqcount_begin(&conf->gen_lock);
7575 	conf->previous_raid_disks = conf->raid_disks;
7576 	conf->raid_disks += mddev->delta_disks;
7577 	conf->prev_chunk_sectors = conf->chunk_sectors;
7578 	conf->chunk_sectors = mddev->new_chunk_sectors;
7579 	conf->prev_algo = conf->algorithm;
7580 	conf->algorithm = mddev->new_layout;
7581 	conf->generation++;
7582 	/* Code that selects data_offset needs to see the generation update
7583 	 * if reshape_progress has been set - so a memory barrier needed.
7584 	 */
7585 	smp_mb();
7586 	if (mddev->reshape_backwards)
7587 		conf->reshape_progress = raid5_size(mddev, 0, 0);
7588 	else
7589 		conf->reshape_progress = 0;
7590 	conf->reshape_safe = conf->reshape_progress;
7591 	write_seqcount_end(&conf->gen_lock);
7592 	spin_unlock_irq(&conf->device_lock);
7593 
7594 	/* Now make sure any requests that proceeded on the assumption
7595 	 * the reshape wasn't running - like Discard or Read - have
7596 	 * completed.
7597 	 */
7598 	mddev_suspend(mddev);
7599 	mddev_resume(mddev);
7600 
7601 	/* Add some new drives, as many as will fit.
7602 	 * We know there are enough to make the newly sized array work.
7603 	 * Don't add devices if we are reducing the number of
7604 	 * devices in the array.  This is because it is not possible
7605 	 * to correctly record the "partially reconstructed" state of
7606 	 * such devices during the reshape and confusion could result.
7607 	 */
7608 	if (mddev->delta_disks >= 0) {
7609 		rdev_for_each(rdev, mddev)
7610 			if (rdev->raid_disk < 0 &&
7611 			    !test_bit(Faulty, &rdev->flags)) {
7612 				if (raid5_add_disk(mddev, rdev) == 0) {
7613 					if (rdev->raid_disk
7614 					    >= conf->previous_raid_disks)
7615 						set_bit(In_sync, &rdev->flags);
7616 					else
7617 						rdev->recovery_offset = 0;
7618 
7619 					if (sysfs_link_rdev(mddev, rdev))
7620 						/* Failure here is OK */;
7621 				}
7622 			} else if (rdev->raid_disk >= conf->previous_raid_disks
7623 				   && !test_bit(Faulty, &rdev->flags)) {
7624 				/* This is a spare that was manually added */
7625 				set_bit(In_sync, &rdev->flags);
7626 			}
7627 
7628 		/* When a reshape changes the number of devices,
7629 		 * ->degraded is measured against the larger of the
7630 		 * pre and post number of devices.
7631 		 */
7632 		spin_lock_irqsave(&conf->device_lock, flags);
7633 		mddev->degraded = calc_degraded(conf);
7634 		spin_unlock_irqrestore(&conf->device_lock, flags);
7635 	}
7636 	mddev->raid_disks = conf->raid_disks;
7637 	mddev->reshape_position = conf->reshape_progress;
7638 	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
7639 
7640 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7641 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7642 	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7643 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7644 	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7645 	mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7646 						"reshape");
7647 	if (!mddev->sync_thread) {
7648 		mddev->recovery = 0;
7649 		spin_lock_irq(&conf->device_lock);
7650 		write_seqcount_begin(&conf->gen_lock);
7651 		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7652 		mddev->new_chunk_sectors =
7653 			conf->chunk_sectors = conf->prev_chunk_sectors;
7654 		mddev->new_layout = conf->algorithm = conf->prev_algo;
7655 		rdev_for_each(rdev, mddev)
7656 			rdev->new_data_offset = rdev->data_offset;
7657 		smp_wmb();
7658 		conf->generation --;
7659 		conf->reshape_progress = MaxSector;
7660 		mddev->reshape_position = MaxSector;
7661 		write_seqcount_end(&conf->gen_lock);
7662 		spin_unlock_irq(&conf->device_lock);
7663 		return -EAGAIN;
7664 	}
7665 	conf->reshape_checkpoint = jiffies;
7666 	md_wakeup_thread(mddev->sync_thread);
7667 	md_new_event(mddev);
7668 	return 0;
7669 }
7670 
7671 /* This is called from the reshape thread and should make any
7672  * changes needed in 'conf'
7673  */
7674 static void end_reshape(struct r5conf *conf)
7675 {
7676 
7677 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7678 		struct md_rdev *rdev;
7679 
7680 		spin_lock_irq(&conf->device_lock);
7681 		conf->previous_raid_disks = conf->raid_disks;
7682 		rdev_for_each(rdev, conf->mddev)
7683 			rdev->data_offset = rdev->new_data_offset;
7684 		smp_wmb();
7685 		conf->reshape_progress = MaxSector;
7686 		conf->mddev->reshape_position = MaxSector;
7687 		spin_unlock_irq(&conf->device_lock);
7688 		wake_up(&conf->wait_for_overlap);
7689 
7690 		/* read-ahead size must cover two whole stripes, which is
7691 		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7692 		 */
7693 		if (conf->mddev->queue) {
7694 			int data_disks = conf->raid_disks - conf->max_degraded;
7695 			int stripe = data_disks * ((conf->chunk_sectors << 9)
7696 						   / PAGE_SIZE);
7697 			if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
7698 				conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
7699 		}
7700 	}
7701 }
7702 
7703 /* This is called from the raid5d thread with mddev_lock held.
7704  * It makes config changes to the device.
7705  */
7706 static void raid5_finish_reshape(struct mddev *mddev)
7707 {
7708 	struct r5conf *conf = mddev->private;
7709 
7710 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7711 
7712 		if (mddev->delta_disks > 0) {
7713 			md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7714 			if (mddev->queue) {
7715 				set_capacity(mddev->gendisk, mddev->array_sectors);
7716 				revalidate_disk(mddev->gendisk);
7717 			}
7718 		} else {
7719 			int d;
7720 			spin_lock_irq(&conf->device_lock);
7721 			mddev->degraded = calc_degraded(conf);
7722 			spin_unlock_irq(&conf->device_lock);
7723 			for (d = conf->raid_disks ;
7724 			     d < conf->raid_disks - mddev->delta_disks;
7725 			     d++) {
7726 				struct md_rdev *rdev = conf->disks[d].rdev;
7727 				if (rdev)
7728 					clear_bit(In_sync, &rdev->flags);
7729 				rdev = conf->disks[d].replacement;
7730 				if (rdev)
7731 					clear_bit(In_sync, &rdev->flags);
7732 			}
7733 		}
7734 		mddev->layout = conf->algorithm;
7735 		mddev->chunk_sectors = conf->chunk_sectors;
7736 		mddev->reshape_position = MaxSector;
7737 		mddev->delta_disks = 0;
7738 		mddev->reshape_backwards = 0;
7739 	}
7740 }
7741 
7742 static void raid5_quiesce(struct mddev *mddev, int state)
7743 {
7744 	struct r5conf *conf = mddev->private;
7745 
7746 	switch(state) {
7747 	case 2: /* resume for a suspend */
7748 		wake_up(&conf->wait_for_overlap);
7749 		break;
7750 
7751 	case 1: /* stop all writes */
7752 		lock_all_device_hash_locks_irq(conf);
7753 		/* '2' tells resync/reshape to pause so that all
7754 		 * active stripes can drain
7755 		 */
7756 		r5c_flush_cache(conf, INT_MAX);
7757 		conf->quiesce = 2;
7758 		wait_event_cmd(conf->wait_for_quiescent,
7759 				    atomic_read(&conf->active_stripes) == 0 &&
7760 				    atomic_read(&conf->active_aligned_reads) == 0,
7761 				    unlock_all_device_hash_locks_irq(conf),
7762 				    lock_all_device_hash_locks_irq(conf));
7763 		conf->quiesce = 1;
7764 		unlock_all_device_hash_locks_irq(conf);
7765 		/* allow reshape to continue */
7766 		wake_up(&conf->wait_for_overlap);
7767 		break;
7768 
7769 	case 0: /* re-enable writes */
7770 		lock_all_device_hash_locks_irq(conf);
7771 		conf->quiesce = 0;
7772 		wake_up(&conf->wait_for_quiescent);
7773 		wake_up(&conf->wait_for_overlap);
7774 		unlock_all_device_hash_locks_irq(conf);
7775 		break;
7776 	}
7777 	r5l_quiesce(conf->log, state);
7778 }
7779 
7780 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
7781 {
7782 	struct r0conf *raid0_conf = mddev->private;
7783 	sector_t sectors;
7784 
7785 	/* for raid0 takeover only one zone is supported */
7786 	if (raid0_conf->nr_strip_zones > 1) {
7787 		pr_warn("md/raid:%s: cannot takeover raid0 with more than one zone.\n",
7788 			mdname(mddev));
7789 		return ERR_PTR(-EINVAL);
7790 	}
7791 
7792 	sectors = raid0_conf->strip_zone[0].zone_end;
7793 	sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
7794 	mddev->dev_sectors = sectors;
7795 	mddev->new_level = level;
7796 	mddev->new_layout = ALGORITHM_PARITY_N;
7797 	mddev->new_chunk_sectors = mddev->chunk_sectors;
7798 	mddev->raid_disks += 1;
7799 	mddev->delta_disks = 1;
7800 	/* make sure it will be not marked as dirty */
7801 	mddev->recovery_cp = MaxSector;
7802 
7803 	return setup_conf(mddev);
7804 }
7805 
7806 static void *raid5_takeover_raid1(struct mddev *mddev)
7807 {
7808 	int chunksect;
7809 	void *ret;
7810 
7811 	if (mddev->raid_disks != 2 ||
7812 	    mddev->degraded > 1)
7813 		return ERR_PTR(-EINVAL);
7814 
7815 	/* Should check if there are write-behind devices? */
7816 
7817 	chunksect = 64*2; /* 64K by default */
7818 
7819 	/* The array must be an exact multiple of chunksize */
7820 	while (chunksect && (mddev->array_sectors & (chunksect-1)))
7821 		chunksect >>= 1;
7822 
7823 	if ((chunksect<<9) < STRIPE_SIZE)
7824 		/* array size does not allow a suitable chunk size */
7825 		return ERR_PTR(-EINVAL);
7826 
7827 	mddev->new_level = 5;
7828 	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
7829 	mddev->new_chunk_sectors = chunksect;
7830 
7831 	ret = setup_conf(mddev);
7832 	if (!IS_ERR_VALUE(ret))
7833 		clear_bit(MD_FAILFAST_SUPPORTED, &mddev->flags);
7834 	return ret;
7835 }
7836 
7837 static void *raid5_takeover_raid6(struct mddev *mddev)
7838 {
7839 	int new_layout;
7840 
7841 	switch (mddev->layout) {
7842 	case ALGORITHM_LEFT_ASYMMETRIC_6:
7843 		new_layout = ALGORITHM_LEFT_ASYMMETRIC;
7844 		break;
7845 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
7846 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
7847 		break;
7848 	case ALGORITHM_LEFT_SYMMETRIC_6:
7849 		new_layout = ALGORITHM_LEFT_SYMMETRIC;
7850 		break;
7851 	case ALGORITHM_RIGHT_SYMMETRIC_6:
7852 		new_layout = ALGORITHM_RIGHT_SYMMETRIC;
7853 		break;
7854 	case ALGORITHM_PARITY_0_6:
7855 		new_layout = ALGORITHM_PARITY_0;
7856 		break;
7857 	case ALGORITHM_PARITY_N:
7858 		new_layout = ALGORITHM_PARITY_N;
7859 		break;
7860 	default:
7861 		return ERR_PTR(-EINVAL);
7862 	}
7863 	mddev->new_level = 5;
7864 	mddev->new_layout = new_layout;
7865 	mddev->delta_disks = -1;
7866 	mddev->raid_disks -= 1;
7867 	return setup_conf(mddev);
7868 }
7869 
7870 static int raid5_check_reshape(struct mddev *mddev)
7871 {
7872 	/* For a 2-drive array, the layout and chunk size can be changed
7873 	 * immediately as not restriping is needed.
7874 	 * For larger arrays we record the new value - after validation
7875 	 * to be used by a reshape pass.
7876 	 */
7877 	struct r5conf *conf = mddev->private;
7878 	int new_chunk = mddev->new_chunk_sectors;
7879 
7880 	if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
7881 		return -EINVAL;
7882 	if (new_chunk > 0) {
7883 		if (!is_power_of_2(new_chunk))
7884 			return -EINVAL;
7885 		if (new_chunk < (PAGE_SIZE>>9))
7886 			return -EINVAL;
7887 		if (mddev->array_sectors & (new_chunk-1))
7888 			/* not factor of array size */
7889 			return -EINVAL;
7890 	}
7891 
7892 	/* They look valid */
7893 
7894 	if (mddev->raid_disks == 2) {
7895 		/* can make the change immediately */
7896 		if (mddev->new_layout >= 0) {
7897 			conf->algorithm = mddev->new_layout;
7898 			mddev->layout = mddev->new_layout;
7899 		}
7900 		if (new_chunk > 0) {
7901 			conf->chunk_sectors = new_chunk ;
7902 			mddev->chunk_sectors = new_chunk;
7903 		}
7904 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
7905 		md_wakeup_thread(mddev->thread);
7906 	}
7907 	return check_reshape(mddev);
7908 }
7909 
7910 static int raid6_check_reshape(struct mddev *mddev)
7911 {
7912 	int new_chunk = mddev->new_chunk_sectors;
7913 
7914 	if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
7915 		return -EINVAL;
7916 	if (new_chunk > 0) {
7917 		if (!is_power_of_2(new_chunk))
7918 			return -EINVAL;
7919 		if (new_chunk < (PAGE_SIZE >> 9))
7920 			return -EINVAL;
7921 		if (mddev->array_sectors & (new_chunk-1))
7922 			/* not factor of array size */
7923 			return -EINVAL;
7924 	}
7925 
7926 	/* They look valid */
7927 	return check_reshape(mddev);
7928 }
7929 
7930 static void *raid5_takeover(struct mddev *mddev)
7931 {
7932 	/* raid5 can take over:
7933 	 *  raid0 - if there is only one strip zone - make it a raid4 layout
7934 	 *  raid1 - if there are two drives.  We need to know the chunk size
7935 	 *  raid4 - trivial - just use a raid4 layout.
7936 	 *  raid6 - Providing it is a *_6 layout
7937 	 */
7938 	if (mddev->level == 0)
7939 		return raid45_takeover_raid0(mddev, 5);
7940 	if (mddev->level == 1)
7941 		return raid5_takeover_raid1(mddev);
7942 	if (mddev->level == 4) {
7943 		mddev->new_layout = ALGORITHM_PARITY_N;
7944 		mddev->new_level = 5;
7945 		return setup_conf(mddev);
7946 	}
7947 	if (mddev->level == 6)
7948 		return raid5_takeover_raid6(mddev);
7949 
7950 	return ERR_PTR(-EINVAL);
7951 }
7952 
7953 static void *raid4_takeover(struct mddev *mddev)
7954 {
7955 	/* raid4 can take over:
7956 	 *  raid0 - if there is only one strip zone
7957 	 *  raid5 - if layout is right
7958 	 */
7959 	if (mddev->level == 0)
7960 		return raid45_takeover_raid0(mddev, 4);
7961 	if (mddev->level == 5 &&
7962 	    mddev->layout == ALGORITHM_PARITY_N) {
7963 		mddev->new_layout = 0;
7964 		mddev->new_level = 4;
7965 		return setup_conf(mddev);
7966 	}
7967 	return ERR_PTR(-EINVAL);
7968 }
7969 
7970 static struct md_personality raid5_personality;
7971 
7972 static void *raid6_takeover(struct mddev *mddev)
7973 {
7974 	/* Currently can only take over a raid5.  We map the
7975 	 * personality to an equivalent raid6 personality
7976 	 * with the Q block at the end.
7977 	 */
7978 	int new_layout;
7979 
7980 	if (mddev->pers != &raid5_personality)
7981 		return ERR_PTR(-EINVAL);
7982 	if (mddev->degraded > 1)
7983 		return ERR_PTR(-EINVAL);
7984 	if (mddev->raid_disks > 253)
7985 		return ERR_PTR(-EINVAL);
7986 	if (mddev->raid_disks < 3)
7987 		return ERR_PTR(-EINVAL);
7988 
7989 	switch (mddev->layout) {
7990 	case ALGORITHM_LEFT_ASYMMETRIC:
7991 		new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
7992 		break;
7993 	case ALGORITHM_RIGHT_ASYMMETRIC:
7994 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
7995 		break;
7996 	case ALGORITHM_LEFT_SYMMETRIC:
7997 		new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
7998 		break;
7999 	case ALGORITHM_RIGHT_SYMMETRIC:
8000 		new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
8001 		break;
8002 	case ALGORITHM_PARITY_0:
8003 		new_layout = ALGORITHM_PARITY_0_6;
8004 		break;
8005 	case ALGORITHM_PARITY_N:
8006 		new_layout = ALGORITHM_PARITY_N;
8007 		break;
8008 	default:
8009 		return ERR_PTR(-EINVAL);
8010 	}
8011 	mddev->new_level = 6;
8012 	mddev->new_layout = new_layout;
8013 	mddev->delta_disks = 1;
8014 	mddev->raid_disks += 1;
8015 	return setup_conf(mddev);
8016 }
8017 
8018 static struct md_personality raid6_personality =
8019 {
8020 	.name		= "raid6",
8021 	.level		= 6,
8022 	.owner		= THIS_MODULE,
8023 	.make_request	= raid5_make_request,
8024 	.run		= raid5_run,
8025 	.free		= raid5_free,
8026 	.status		= raid5_status,
8027 	.error_handler	= raid5_error,
8028 	.hot_add_disk	= raid5_add_disk,
8029 	.hot_remove_disk= raid5_remove_disk,
8030 	.spare_active	= raid5_spare_active,
8031 	.sync_request	= raid5_sync_request,
8032 	.resize		= raid5_resize,
8033 	.size		= raid5_size,
8034 	.check_reshape	= raid6_check_reshape,
8035 	.start_reshape  = raid5_start_reshape,
8036 	.finish_reshape = raid5_finish_reshape,
8037 	.quiesce	= raid5_quiesce,
8038 	.takeover	= raid6_takeover,
8039 	.congested	= raid5_congested,
8040 };
8041 static struct md_personality raid5_personality =
8042 {
8043 	.name		= "raid5",
8044 	.level		= 5,
8045 	.owner		= THIS_MODULE,
8046 	.make_request	= raid5_make_request,
8047 	.run		= raid5_run,
8048 	.free		= raid5_free,
8049 	.status		= raid5_status,
8050 	.error_handler	= raid5_error,
8051 	.hot_add_disk	= raid5_add_disk,
8052 	.hot_remove_disk= raid5_remove_disk,
8053 	.spare_active	= raid5_spare_active,
8054 	.sync_request	= raid5_sync_request,
8055 	.resize		= raid5_resize,
8056 	.size		= raid5_size,
8057 	.check_reshape	= raid5_check_reshape,
8058 	.start_reshape  = raid5_start_reshape,
8059 	.finish_reshape = raid5_finish_reshape,
8060 	.quiesce	= raid5_quiesce,
8061 	.takeover	= raid5_takeover,
8062 	.congested	= raid5_congested,
8063 };
8064 
8065 static struct md_personality raid4_personality =
8066 {
8067 	.name		= "raid4",
8068 	.level		= 4,
8069 	.owner		= THIS_MODULE,
8070 	.make_request	= raid5_make_request,
8071 	.run		= raid5_run,
8072 	.free		= raid5_free,
8073 	.status		= raid5_status,
8074 	.error_handler	= raid5_error,
8075 	.hot_add_disk	= raid5_add_disk,
8076 	.hot_remove_disk= raid5_remove_disk,
8077 	.spare_active	= raid5_spare_active,
8078 	.sync_request	= raid5_sync_request,
8079 	.resize		= raid5_resize,
8080 	.size		= raid5_size,
8081 	.check_reshape	= raid5_check_reshape,
8082 	.start_reshape  = raid5_start_reshape,
8083 	.finish_reshape = raid5_finish_reshape,
8084 	.quiesce	= raid5_quiesce,
8085 	.takeover	= raid4_takeover,
8086 	.congested	= raid5_congested,
8087 };
8088 
8089 static int __init raid5_init(void)
8090 {
8091 	int ret;
8092 
8093 	raid5_wq = alloc_workqueue("raid5wq",
8094 		WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
8095 	if (!raid5_wq)
8096 		return -ENOMEM;
8097 
8098 	ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
8099 				      "md/raid5:prepare",
8100 				      raid456_cpu_up_prepare,
8101 				      raid456_cpu_dead);
8102 	if (ret) {
8103 		destroy_workqueue(raid5_wq);
8104 		return ret;
8105 	}
8106 	register_md_personality(&raid6_personality);
8107 	register_md_personality(&raid5_personality);
8108 	register_md_personality(&raid4_personality);
8109 	return 0;
8110 }
8111 
8112 static void raid5_exit(void)
8113 {
8114 	unregister_md_personality(&raid6_personality);
8115 	unregister_md_personality(&raid5_personality);
8116 	unregister_md_personality(&raid4_personality);
8117 	cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
8118 	destroy_workqueue(raid5_wq);
8119 }
8120 
8121 module_init(raid5_init);
8122 module_exit(raid5_exit);
8123 MODULE_LICENSE("GPL");
8124 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
8125 MODULE_ALIAS("md-personality-4"); /* RAID5 */
8126 MODULE_ALIAS("md-raid5");
8127 MODULE_ALIAS("md-raid4");
8128 MODULE_ALIAS("md-level-5");
8129 MODULE_ALIAS("md-level-4");
8130 MODULE_ALIAS("md-personality-8"); /* RAID6 */
8131 MODULE_ALIAS("md-raid6");
8132 MODULE_ALIAS("md-level-6");
8133 
8134 /* This used to be two separate modules, they were: */
8135 MODULE_ALIAS("raid5");
8136 MODULE_ALIAS("raid6");
8137