xref: /linux/drivers/md/raid5.c (revision 96f30c8f0aa9923aa39b30bcaefeacf88b490231)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * raid5.c : Multiple Devices driver for Linux
4  *	   Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
5  *	   Copyright (C) 1999, 2000 Ingo Molnar
6  *	   Copyright (C) 2002, 2003 H. Peter Anvin
7  *
8  * RAID-4/5/6 management functions.
9  * Thanks to Penguin Computing for making the RAID-6 development possible
10  * by donating a test server!
11  */
12 
13 /*
14  * BITMAP UNPLUGGING:
15  *
16  * The sequencing for updating the bitmap reliably is a little
17  * subtle (and I got it wrong the first time) so it deserves some
18  * explanation.
19  *
20  * We group bitmap updates into batches.  Each batch has a number.
21  * We may write out several batches at once, but that isn't very important.
22  * conf->seq_write is the number of the last batch successfully written.
23  * conf->seq_flush is the number of the last batch that was closed to
24  *    new additions.
25  * When we discover that we will need to write to any block in a stripe
26  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
27  * the number of the batch it will be in. This is seq_flush+1.
28  * When we are ready to do a write, if that batch hasn't been written yet,
29  *   we plug the array and queue the stripe for later.
30  * When an unplug happens, we increment bm_flush, thus closing the current
31  *   batch.
32  * When we notice that bm_flush > bm_write, we write out all pending updates
33  * to the bitmap, and advance bm_write to where bm_flush was.
34  * This may occasionally write a bit out twice, but is sure never to
35  * miss any bits.
36  */
37 
38 #include <linux/blkdev.h>
39 #include <linux/kthread.h>
40 #include <linux/raid/pq.h>
41 #include <linux/async_tx.h>
42 #include <linux/module.h>
43 #include <linux/async.h>
44 #include <linux/seq_file.h>
45 #include <linux/cpu.h>
46 #include <linux/slab.h>
47 #include <linux/ratelimit.h>
48 #include <linux/nodemask.h>
49 
50 #include <trace/events/block.h>
51 #include <linux/list_sort.h>
52 
53 #include "md.h"
54 #include "raid5.h"
55 #include "raid0.h"
56 #include "md-bitmap.h"
57 #include "raid5-log.h"
58 
59 #define UNSUPPORTED_MDDEV_FLAGS	(1L << MD_FAILFAST_SUPPORTED)
60 
61 #define cpu_to_group(cpu) cpu_to_node(cpu)
62 #define ANY_GROUP NUMA_NO_NODE
63 
64 #define RAID5_MAX_REQ_STRIPES 256
65 
66 static bool devices_handle_discard_safely = false;
67 module_param(devices_handle_discard_safely, bool, 0644);
68 MODULE_PARM_DESC(devices_handle_discard_safely,
69 		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
70 static struct workqueue_struct *raid5_wq;
71 
72 static void raid5_quiesce(struct mddev *mddev, int quiesce);
73 
74 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
75 {
76 	int hash = (sect >> RAID5_STRIPE_SHIFT(conf)) & HASH_MASK;
77 	return &conf->stripe_hashtbl[hash];
78 }
79 
80 static inline int stripe_hash_locks_hash(struct r5conf *conf, sector_t sect)
81 {
82 	return (sect >> RAID5_STRIPE_SHIFT(conf)) & STRIPE_HASH_LOCKS_MASK;
83 }
84 
85 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
86 	__acquires(&conf->device_lock)
87 {
88 	spin_lock_irq(conf->hash_locks + hash);
89 	spin_lock(&conf->device_lock);
90 }
91 
92 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
93 	__releases(&conf->device_lock)
94 {
95 	spin_unlock(&conf->device_lock);
96 	spin_unlock_irq(conf->hash_locks + hash);
97 }
98 
99 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
100 	__acquires(&conf->device_lock)
101 {
102 	int i;
103 	spin_lock_irq(conf->hash_locks);
104 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
105 		spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
106 	spin_lock(&conf->device_lock);
107 }
108 
109 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
110 	__releases(&conf->device_lock)
111 {
112 	int i;
113 	spin_unlock(&conf->device_lock);
114 	for (i = NR_STRIPE_HASH_LOCKS - 1; i; i--)
115 		spin_unlock(conf->hash_locks + i);
116 	spin_unlock_irq(conf->hash_locks);
117 }
118 
119 /* Find first data disk in a raid6 stripe */
120 static inline int raid6_d0(struct stripe_head *sh)
121 {
122 	if (sh->ddf_layout)
123 		/* ddf always start from first device */
124 		return 0;
125 	/* md starts just after Q block */
126 	if (sh->qd_idx == sh->disks - 1)
127 		return 0;
128 	else
129 		return sh->qd_idx + 1;
130 }
131 static inline int raid6_next_disk(int disk, int raid_disks)
132 {
133 	disk++;
134 	return (disk < raid_disks) ? disk : 0;
135 }
136 
137 /* When walking through the disks in a raid5, starting at raid6_d0,
138  * We need to map each disk to a 'slot', where the data disks are slot
139  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
140  * is raid_disks-1.  This help does that mapping.
141  */
142 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
143 			     int *count, int syndrome_disks)
144 {
145 	int slot = *count;
146 
147 	if (sh->ddf_layout)
148 		(*count)++;
149 	if (idx == sh->pd_idx)
150 		return syndrome_disks;
151 	if (idx == sh->qd_idx)
152 		return syndrome_disks + 1;
153 	if (!sh->ddf_layout)
154 		(*count)++;
155 	return slot;
156 }
157 
158 static void print_raid5_conf(struct r5conf *conf);
159 
160 static int stripe_operations_active(struct stripe_head *sh)
161 {
162 	return sh->check_state || sh->reconstruct_state ||
163 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
164 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
165 }
166 
167 static bool stripe_is_lowprio(struct stripe_head *sh)
168 {
169 	return (test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state) ||
170 		test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) &&
171 	       !test_bit(STRIPE_R5C_CACHING, &sh->state);
172 }
173 
174 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
175 	__must_hold(&sh->raid_conf->device_lock)
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 		if (stripe_is_lowprio(sh))
191 			list_add_tail(&sh->lru, &group->loprio_list);
192 		else
193 			list_add_tail(&sh->lru, &group->handle_list);
194 		group->stripes_cnt++;
195 		sh->group = group;
196 	}
197 
198 	if (conf->worker_cnt_per_group == 0) {
199 		md_wakeup_thread(conf->mddev->thread);
200 		return;
201 	}
202 
203 	group = conf->worker_groups + cpu_to_group(sh->cpu);
204 
205 	group->workers[0].working = true;
206 	/* at least one worker should run to avoid race */
207 	queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
208 
209 	thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
210 	/* wakeup more workers */
211 	for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
212 		if (group->workers[i].working == false) {
213 			group->workers[i].working = true;
214 			queue_work_on(sh->cpu, raid5_wq,
215 				      &group->workers[i].work);
216 			thread_cnt--;
217 		}
218 	}
219 }
220 
221 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
222 			      struct list_head *temp_inactive_list)
223 	__must_hold(&conf->device_lock)
224 {
225 	int i;
226 	int injournal = 0;	/* number of date pages with R5_InJournal */
227 
228 	BUG_ON(!list_empty(&sh->lru));
229 	BUG_ON(atomic_read(&conf->active_stripes)==0);
230 
231 	if (r5c_is_writeback(conf->log))
232 		for (i = sh->disks; i--; )
233 			if (test_bit(R5_InJournal, &sh->dev[i].flags))
234 				injournal++;
235 	/*
236 	 * In the following cases, the stripe cannot be released to cached
237 	 * lists. Therefore, we make the stripe write out and set
238 	 * STRIPE_HANDLE:
239 	 *   1. when quiesce in r5c write back;
240 	 *   2. when resync is requested fot the stripe.
241 	 */
242 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) ||
243 	    (conf->quiesce && r5c_is_writeback(conf->log) &&
244 	     !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0)) {
245 		if (test_bit(STRIPE_R5C_CACHING, &sh->state))
246 			r5c_make_stripe_write_out(sh);
247 		set_bit(STRIPE_HANDLE, &sh->state);
248 	}
249 
250 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
251 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
252 		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
253 			list_add_tail(&sh->lru, &conf->delayed_list);
254 		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
255 			   sh->bm_seq - conf->seq_write > 0)
256 			list_add_tail(&sh->lru, &conf->bitmap_list);
257 		else {
258 			clear_bit(STRIPE_DELAYED, &sh->state);
259 			clear_bit(STRIPE_BIT_DELAY, &sh->state);
260 			if (conf->worker_cnt_per_group == 0) {
261 				if (stripe_is_lowprio(sh))
262 					list_add_tail(&sh->lru,
263 							&conf->loprio_list);
264 				else
265 					list_add_tail(&sh->lru,
266 							&conf->handle_list);
267 			} else {
268 				raid5_wakeup_stripe_thread(sh);
269 				return;
270 			}
271 		}
272 		md_wakeup_thread(conf->mddev->thread);
273 	} else {
274 		BUG_ON(stripe_operations_active(sh));
275 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
276 			if (atomic_dec_return(&conf->preread_active_stripes)
277 			    < IO_THRESHOLD)
278 				md_wakeup_thread(conf->mddev->thread);
279 		atomic_dec(&conf->active_stripes);
280 		if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
281 			if (!r5c_is_writeback(conf->log))
282 				list_add_tail(&sh->lru, temp_inactive_list);
283 			else {
284 				WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
285 				if (injournal == 0)
286 					list_add_tail(&sh->lru, temp_inactive_list);
287 				else if (injournal == conf->raid_disks - conf->max_degraded) {
288 					/* full stripe */
289 					if (!test_and_set_bit(STRIPE_R5C_FULL_STRIPE, &sh->state))
290 						atomic_inc(&conf->r5c_cached_full_stripes);
291 					if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
292 						atomic_dec(&conf->r5c_cached_partial_stripes);
293 					list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
294 					r5c_check_cached_full_stripe(conf);
295 				} else
296 					/*
297 					 * STRIPE_R5C_PARTIAL_STRIPE is set in
298 					 * r5c_try_caching_write(). No need to
299 					 * set it again.
300 					 */
301 					list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
302 			}
303 		}
304 	}
305 }
306 
307 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
308 			     struct list_head *temp_inactive_list)
309 	__must_hold(&conf->device_lock)
310 {
311 	if (atomic_dec_and_test(&sh->count))
312 		do_release_stripe(conf, sh, temp_inactive_list);
313 }
314 
315 /*
316  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
317  *
318  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
319  * given time. Adding stripes only takes device lock, while deleting stripes
320  * only takes hash lock.
321  */
322 static void release_inactive_stripe_list(struct r5conf *conf,
323 					 struct list_head *temp_inactive_list,
324 					 int hash)
325 {
326 	int size;
327 	bool do_wakeup = false;
328 	unsigned long flags;
329 
330 	if (hash == NR_STRIPE_HASH_LOCKS) {
331 		size = NR_STRIPE_HASH_LOCKS;
332 		hash = NR_STRIPE_HASH_LOCKS - 1;
333 	} else
334 		size = 1;
335 	while (size) {
336 		struct list_head *list = &temp_inactive_list[size - 1];
337 
338 		/*
339 		 * We don't hold any lock here yet, raid5_get_active_stripe() might
340 		 * remove stripes from the list
341 		 */
342 		if (!list_empty_careful(list)) {
343 			spin_lock_irqsave(conf->hash_locks + hash, flags);
344 			if (list_empty(conf->inactive_list + hash) &&
345 			    !list_empty(list))
346 				atomic_dec(&conf->empty_inactive_list_nr);
347 			list_splice_tail_init(list, conf->inactive_list + hash);
348 			do_wakeup = true;
349 			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
350 		}
351 		size--;
352 		hash--;
353 	}
354 
355 	if (do_wakeup) {
356 		wake_up(&conf->wait_for_stripe);
357 		if (atomic_read(&conf->active_stripes) == 0)
358 			wake_up(&conf->wait_for_quiescent);
359 		if (conf->retry_read_aligned)
360 			md_wakeup_thread(conf->mddev->thread);
361 	}
362 }
363 
364 static int release_stripe_list(struct r5conf *conf,
365 			       struct list_head *temp_inactive_list)
366 	__must_hold(&conf->device_lock)
367 {
368 	struct stripe_head *sh, *t;
369 	int count = 0;
370 	struct llist_node *head;
371 
372 	head = llist_del_all(&conf->released_stripes);
373 	head = llist_reverse_order(head);
374 	llist_for_each_entry_safe(sh, t, head, release_list) {
375 		int hash;
376 
377 		/* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
378 		smp_mb();
379 		clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
380 		/*
381 		 * Don't worry the bit is set here, because if the bit is set
382 		 * again, the count is always > 1. This is true for
383 		 * STRIPE_ON_UNPLUG_LIST bit too.
384 		 */
385 		hash = sh->hash_lock_index;
386 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
387 		count++;
388 	}
389 
390 	return count;
391 }
392 
393 void raid5_release_stripe(struct stripe_head *sh)
394 {
395 	struct r5conf *conf = sh->raid_conf;
396 	unsigned long flags;
397 	struct list_head list;
398 	int hash;
399 	bool wakeup;
400 
401 	/* Avoid release_list until the last reference.
402 	 */
403 	if (atomic_add_unless(&sh->count, -1, 1))
404 		return;
405 
406 	if (unlikely(!conf->mddev->thread) ||
407 		test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
408 		goto slow_path;
409 	wakeup = llist_add(&sh->release_list, &conf->released_stripes);
410 	if (wakeup)
411 		md_wakeup_thread(conf->mddev->thread);
412 	return;
413 slow_path:
414 	/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
415 	if (atomic_dec_and_lock_irqsave(&sh->count, &conf->device_lock, flags)) {
416 		INIT_LIST_HEAD(&list);
417 		hash = sh->hash_lock_index;
418 		do_release_stripe(conf, sh, &list);
419 		spin_unlock_irqrestore(&conf->device_lock, flags);
420 		release_inactive_stripe_list(conf, &list, hash);
421 	}
422 }
423 
424 static inline void remove_hash(struct stripe_head *sh)
425 {
426 	pr_debug("remove_hash(), stripe %llu\n",
427 		(unsigned long long)sh->sector);
428 
429 	hlist_del_init(&sh->hash);
430 }
431 
432 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
433 {
434 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
435 
436 	pr_debug("insert_hash(), stripe %llu\n",
437 		(unsigned long long)sh->sector);
438 
439 	hlist_add_head(&sh->hash, hp);
440 }
441 
442 /* find an idle stripe, make sure it is unhashed, and return it. */
443 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
444 {
445 	struct stripe_head *sh = NULL;
446 	struct list_head *first;
447 
448 	if (list_empty(conf->inactive_list + hash))
449 		goto out;
450 	first = (conf->inactive_list + hash)->next;
451 	sh = list_entry(first, struct stripe_head, lru);
452 	list_del_init(first);
453 	remove_hash(sh);
454 	atomic_inc(&conf->active_stripes);
455 	BUG_ON(hash != sh->hash_lock_index);
456 	if (list_empty(conf->inactive_list + hash))
457 		atomic_inc(&conf->empty_inactive_list_nr);
458 out:
459 	return sh;
460 }
461 
462 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
463 static void free_stripe_pages(struct stripe_head *sh)
464 {
465 	int i;
466 	struct page *p;
467 
468 	/* Have not allocate page pool */
469 	if (!sh->pages)
470 		return;
471 
472 	for (i = 0; i < sh->nr_pages; i++) {
473 		p = sh->pages[i];
474 		if (p)
475 			put_page(p);
476 		sh->pages[i] = NULL;
477 	}
478 }
479 
480 static int alloc_stripe_pages(struct stripe_head *sh, gfp_t gfp)
481 {
482 	int i;
483 	struct page *p;
484 
485 	for (i = 0; i < sh->nr_pages; i++) {
486 		/* The page have allocated. */
487 		if (sh->pages[i])
488 			continue;
489 
490 		p = alloc_page(gfp);
491 		if (!p) {
492 			free_stripe_pages(sh);
493 			return -ENOMEM;
494 		}
495 		sh->pages[i] = p;
496 	}
497 	return 0;
498 }
499 
500 static int
501 init_stripe_shared_pages(struct stripe_head *sh, struct r5conf *conf, int disks)
502 {
503 	int nr_pages, cnt;
504 
505 	if (sh->pages)
506 		return 0;
507 
508 	/* Each of the sh->dev[i] need one conf->stripe_size */
509 	cnt = PAGE_SIZE / conf->stripe_size;
510 	nr_pages = (disks + cnt - 1) / cnt;
511 
512 	sh->pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
513 	if (!sh->pages)
514 		return -ENOMEM;
515 	sh->nr_pages = nr_pages;
516 	sh->stripes_per_page = cnt;
517 	return 0;
518 }
519 #endif
520 
521 static void shrink_buffers(struct stripe_head *sh)
522 {
523 	int i;
524 	int num = sh->raid_conf->pool_size;
525 
526 #if PAGE_SIZE == DEFAULT_STRIPE_SIZE
527 	for (i = 0; i < num ; i++) {
528 		struct page *p;
529 
530 		WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
531 		p = sh->dev[i].page;
532 		if (!p)
533 			continue;
534 		sh->dev[i].page = NULL;
535 		put_page(p);
536 	}
537 #else
538 	for (i = 0; i < num; i++)
539 		sh->dev[i].page = NULL;
540 	free_stripe_pages(sh); /* Free pages */
541 #endif
542 }
543 
544 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
545 {
546 	int i;
547 	int num = sh->raid_conf->pool_size;
548 
549 #if PAGE_SIZE == DEFAULT_STRIPE_SIZE
550 	for (i = 0; i < num; i++) {
551 		struct page *page;
552 
553 		if (!(page = alloc_page(gfp))) {
554 			return 1;
555 		}
556 		sh->dev[i].page = page;
557 		sh->dev[i].orig_page = page;
558 		sh->dev[i].offset = 0;
559 	}
560 #else
561 	if (alloc_stripe_pages(sh, gfp))
562 		return -ENOMEM;
563 
564 	for (i = 0; i < num; i++) {
565 		sh->dev[i].page = raid5_get_dev_page(sh, i);
566 		sh->dev[i].orig_page = sh->dev[i].page;
567 		sh->dev[i].offset = raid5_get_page_offset(sh, i);
568 	}
569 #endif
570 	return 0;
571 }
572 
573 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
574 			    struct stripe_head *sh);
575 
576 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
577 {
578 	struct r5conf *conf = sh->raid_conf;
579 	int i, seq;
580 
581 	BUG_ON(atomic_read(&sh->count) != 0);
582 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
583 	BUG_ON(stripe_operations_active(sh));
584 	BUG_ON(sh->batch_head);
585 
586 	pr_debug("init_stripe called, stripe %llu\n",
587 		(unsigned long long)sector);
588 retry:
589 	seq = read_seqcount_begin(&conf->gen_lock);
590 	sh->generation = conf->generation - previous;
591 	sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
592 	sh->sector = sector;
593 	stripe_set_idx(sector, conf, previous, sh);
594 	sh->state = 0;
595 
596 	for (i = sh->disks; i--; ) {
597 		struct r5dev *dev = &sh->dev[i];
598 
599 		if (dev->toread || dev->read || dev->towrite || dev->written ||
600 		    test_bit(R5_LOCKED, &dev->flags)) {
601 			pr_err("sector=%llx i=%d %p %p %p %p %d\n",
602 			       (unsigned long long)sh->sector, i, dev->toread,
603 			       dev->read, dev->towrite, dev->written,
604 			       test_bit(R5_LOCKED, &dev->flags));
605 			WARN_ON(1);
606 		}
607 		dev->flags = 0;
608 		dev->sector = raid5_compute_blocknr(sh, i, previous);
609 	}
610 	if (read_seqcount_retry(&conf->gen_lock, seq))
611 		goto retry;
612 	sh->overwrite_disks = 0;
613 	insert_hash(conf, sh);
614 	sh->cpu = smp_processor_id();
615 	set_bit(STRIPE_BATCH_READY, &sh->state);
616 }
617 
618 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
619 					 short generation)
620 {
621 	struct stripe_head *sh;
622 
623 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
624 	hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
625 		if (sh->sector == sector && sh->generation == generation)
626 			return sh;
627 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
628 	return NULL;
629 }
630 
631 static struct stripe_head *find_get_stripe(struct r5conf *conf,
632 		sector_t sector, short generation, int hash)
633 {
634 	int inc_empty_inactive_list_flag;
635 	struct stripe_head *sh;
636 
637 	sh = __find_stripe(conf, sector, generation);
638 	if (!sh)
639 		return NULL;
640 
641 	if (atomic_inc_not_zero(&sh->count))
642 		return sh;
643 
644 	/*
645 	 * Slow path. The reference count is zero which means the stripe must
646 	 * be on a list (sh->lru). Must remove the stripe from the list that
647 	 * references it with the device_lock held.
648 	 */
649 
650 	spin_lock(&conf->device_lock);
651 	if (!atomic_read(&sh->count)) {
652 		if (!test_bit(STRIPE_HANDLE, &sh->state))
653 			atomic_inc(&conf->active_stripes);
654 		BUG_ON(list_empty(&sh->lru) &&
655 		       !test_bit(STRIPE_EXPANDING, &sh->state));
656 		inc_empty_inactive_list_flag = 0;
657 		if (!list_empty(conf->inactive_list + hash))
658 			inc_empty_inactive_list_flag = 1;
659 		list_del_init(&sh->lru);
660 		if (list_empty(conf->inactive_list + hash) &&
661 		    inc_empty_inactive_list_flag)
662 			atomic_inc(&conf->empty_inactive_list_nr);
663 		if (sh->group) {
664 			sh->group->stripes_cnt--;
665 			sh->group = NULL;
666 		}
667 	}
668 	atomic_inc(&sh->count);
669 	spin_unlock(&conf->device_lock);
670 
671 	return sh;
672 }
673 
674 /*
675  * Need to check if array has failed when deciding whether to:
676  *  - start an array
677  *  - remove non-faulty devices
678  *  - add a spare
679  *  - allow a reshape
680  * This determination is simple when no reshape is happening.
681  * However if there is a reshape, we need to carefully check
682  * both the before and after sections.
683  * This is because some failed devices may only affect one
684  * of the two sections, and some non-in_sync devices may
685  * be insync in the section most affected by failed devices.
686  *
687  * Most calls to this function hold &conf->device_lock. Calls
688  * in raid5_run() do not require the lock as no other threads
689  * have been started yet.
690  */
691 int raid5_calc_degraded(struct r5conf *conf)
692 {
693 	int degraded, degraded2;
694 	int i;
695 
696 	degraded = 0;
697 	for (i = 0; i < conf->previous_raid_disks; i++) {
698 		struct md_rdev *rdev = READ_ONCE(conf->disks[i].rdev);
699 
700 		if (rdev && test_bit(Faulty, &rdev->flags))
701 			rdev = READ_ONCE(conf->disks[i].replacement);
702 		if (!rdev || test_bit(Faulty, &rdev->flags))
703 			degraded++;
704 		else if (test_bit(In_sync, &rdev->flags))
705 			;
706 		else
707 			/* not in-sync or faulty.
708 			 * If the reshape increases the number of devices,
709 			 * this is being recovered by the reshape, so
710 			 * this 'previous' section is not in_sync.
711 			 * If the number of devices is being reduced however,
712 			 * the device can only be part of the array if
713 			 * we are reverting a reshape, so this section will
714 			 * be in-sync.
715 			 */
716 			if (conf->raid_disks >= conf->previous_raid_disks)
717 				degraded++;
718 	}
719 	if (conf->raid_disks == conf->previous_raid_disks)
720 		return degraded;
721 	degraded2 = 0;
722 	for (i = 0; i < conf->raid_disks; i++) {
723 		struct md_rdev *rdev = READ_ONCE(conf->disks[i].rdev);
724 
725 		if (rdev && test_bit(Faulty, &rdev->flags))
726 			rdev = READ_ONCE(conf->disks[i].replacement);
727 		if (!rdev || test_bit(Faulty, &rdev->flags))
728 			degraded2++;
729 		else if (test_bit(In_sync, &rdev->flags))
730 			;
731 		else
732 			/* not in-sync or faulty.
733 			 * If reshape increases the number of devices, this
734 			 * section has already been recovered, else it
735 			 * almost certainly hasn't.
736 			 */
737 			if (conf->raid_disks <= conf->previous_raid_disks)
738 				degraded2++;
739 	}
740 	if (degraded2 > degraded)
741 		return degraded2;
742 	return degraded;
743 }
744 
745 static bool has_failed(struct r5conf *conf)
746 {
747 	int degraded = conf->mddev->degraded;
748 
749 	if (test_bit(MD_BROKEN, &conf->mddev->flags))
750 		return true;
751 
752 	if (conf->mddev->reshape_position != MaxSector)
753 		degraded = raid5_calc_degraded(conf);
754 
755 	return degraded > conf->max_degraded;
756 }
757 
758 enum stripe_result {
759 	STRIPE_SUCCESS = 0,
760 	STRIPE_RETRY,
761 	STRIPE_SCHEDULE_AND_RETRY,
762 	STRIPE_FAIL,
763 	STRIPE_WAIT_RESHAPE,
764 };
765 
766 struct stripe_request_ctx {
767 	/* a reference to the last stripe_head for batching */
768 	struct stripe_head *batch_last;
769 
770 	/* first sector in the request */
771 	sector_t first_sector;
772 
773 	/* last sector in the request */
774 	sector_t last_sector;
775 
776 	/*
777 	 * bitmap to track stripe sectors that have been added to stripes
778 	 * add one to account for unaligned requests
779 	 */
780 	DECLARE_BITMAP(sectors_to_do, RAID5_MAX_REQ_STRIPES + 1);
781 
782 	/* the request had REQ_PREFLUSH, cleared after the first stripe_head */
783 	bool do_flush;
784 };
785 
786 /*
787  * Block until another thread clears R5_INACTIVE_BLOCKED or
788  * there are fewer than 3/4 the maximum number of active stripes
789  * and there is an inactive stripe available.
790  */
791 static bool is_inactive_blocked(struct r5conf *conf, int hash)
792 {
793 	if (list_empty(conf->inactive_list + hash))
794 		return false;
795 
796 	if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
797 		return true;
798 
799 	return (atomic_read(&conf->active_stripes) <
800 		(conf->max_nr_stripes * 3 / 4));
801 }
802 
803 struct stripe_head *raid5_get_active_stripe(struct r5conf *conf,
804 		struct stripe_request_ctx *ctx, sector_t sector,
805 		unsigned int flags)
806 {
807 	struct stripe_head *sh;
808 	int hash = stripe_hash_locks_hash(conf, sector);
809 	int previous = !!(flags & R5_GAS_PREVIOUS);
810 
811 	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
812 
813 	spin_lock_irq(conf->hash_locks + hash);
814 
815 	for (;;) {
816 		if (!(flags & R5_GAS_NOQUIESCE) && conf->quiesce) {
817 			/*
818 			 * Must release the reference to batch_last before
819 			 * waiting, on quiesce, otherwise the batch_last will
820 			 * hold a reference to a stripe and raid5_quiesce()
821 			 * will deadlock waiting for active_stripes to go to
822 			 * zero.
823 			 */
824 			if (ctx && ctx->batch_last) {
825 				raid5_release_stripe(ctx->batch_last);
826 				ctx->batch_last = NULL;
827 			}
828 
829 			wait_event_lock_irq(conf->wait_for_quiescent,
830 					    !conf->quiesce,
831 					    *(conf->hash_locks + hash));
832 		}
833 
834 		sh = find_get_stripe(conf, sector, conf->generation - previous,
835 				     hash);
836 		if (sh)
837 			break;
838 
839 		if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
840 			sh = get_free_stripe(conf, hash);
841 			if (sh) {
842 				r5c_check_stripe_cache_usage(conf);
843 				init_stripe(sh, sector, previous);
844 				atomic_inc(&sh->count);
845 				break;
846 			}
847 
848 			if (!test_bit(R5_DID_ALLOC, &conf->cache_state))
849 				set_bit(R5_ALLOC_MORE, &conf->cache_state);
850 		}
851 
852 		if (flags & R5_GAS_NOBLOCK)
853 			break;
854 
855 		set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
856 		r5l_wake_reclaim(conf->log, 0);
857 
858 		/* release batch_last before wait to avoid risk of deadlock */
859 		if (ctx && ctx->batch_last) {
860 			raid5_release_stripe(ctx->batch_last);
861 			ctx->batch_last = NULL;
862 		}
863 
864 		wait_event_lock_irq(conf->wait_for_stripe,
865 				    is_inactive_blocked(conf, hash),
866 				    *(conf->hash_locks + hash));
867 		clear_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
868 	}
869 
870 	spin_unlock_irq(conf->hash_locks + hash);
871 	return sh;
872 }
873 
874 static bool is_full_stripe_write(struct stripe_head *sh)
875 {
876 	BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
877 	return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
878 }
879 
880 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
881 		__acquires(&sh1->stripe_lock)
882 		__acquires(&sh2->stripe_lock)
883 {
884 	if (sh1 > sh2) {
885 		spin_lock_irq(&sh2->stripe_lock);
886 		spin_lock_nested(&sh1->stripe_lock, 1);
887 	} else {
888 		spin_lock_irq(&sh1->stripe_lock);
889 		spin_lock_nested(&sh2->stripe_lock, 1);
890 	}
891 }
892 
893 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
894 		__releases(&sh1->stripe_lock)
895 		__releases(&sh2->stripe_lock)
896 {
897 	spin_unlock(&sh1->stripe_lock);
898 	spin_unlock_irq(&sh2->stripe_lock);
899 }
900 
901 /* Only freshly new full stripe normal write stripe can be added to a batch list */
902 static bool stripe_can_batch(struct stripe_head *sh)
903 {
904 	struct r5conf *conf = sh->raid_conf;
905 
906 	if (raid5_has_log(conf) || raid5_has_ppl(conf))
907 		return false;
908 	return test_bit(STRIPE_BATCH_READY, &sh->state) &&
909 		!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
910 		is_full_stripe_write(sh);
911 }
912 
913 /* we only do back search */
914 static void stripe_add_to_batch_list(struct r5conf *conf,
915 		struct stripe_head *sh, struct stripe_head *last_sh)
916 {
917 	struct stripe_head *head;
918 	sector_t head_sector, tmp_sec;
919 	int hash;
920 	int dd_idx;
921 
922 	/* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
923 	tmp_sec = sh->sector;
924 	if (!sector_div(tmp_sec, conf->chunk_sectors))
925 		return;
926 	head_sector = sh->sector - RAID5_STRIPE_SECTORS(conf);
927 
928 	if (last_sh && head_sector == last_sh->sector) {
929 		head = last_sh;
930 		atomic_inc(&head->count);
931 	} else {
932 		hash = stripe_hash_locks_hash(conf, head_sector);
933 		spin_lock_irq(conf->hash_locks + hash);
934 		head = find_get_stripe(conf, head_sector, conf->generation,
935 				       hash);
936 		spin_unlock_irq(conf->hash_locks + hash);
937 		if (!head)
938 			return;
939 		if (!stripe_can_batch(head))
940 			goto out;
941 	}
942 
943 	lock_two_stripes(head, sh);
944 	/* clear_batch_ready clear the flag */
945 	if (!stripe_can_batch(head) || !stripe_can_batch(sh))
946 		goto unlock_out;
947 
948 	if (sh->batch_head)
949 		goto unlock_out;
950 
951 	dd_idx = 0;
952 	while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
953 		dd_idx++;
954 	if (head->dev[dd_idx].towrite->bi_opf != sh->dev[dd_idx].towrite->bi_opf ||
955 	    bio_op(head->dev[dd_idx].towrite) != bio_op(sh->dev[dd_idx].towrite))
956 		goto unlock_out;
957 
958 	if (head->batch_head) {
959 		spin_lock(&head->batch_head->batch_lock);
960 		/* This batch list is already running */
961 		if (!stripe_can_batch(head)) {
962 			spin_unlock(&head->batch_head->batch_lock);
963 			goto unlock_out;
964 		}
965 		/*
966 		 * We must assign batch_head of this stripe within the
967 		 * batch_lock, otherwise clear_batch_ready of batch head
968 		 * stripe could clear BATCH_READY bit of this stripe and
969 		 * this stripe->batch_head doesn't get assigned, which
970 		 * could confuse clear_batch_ready for this stripe
971 		 */
972 		sh->batch_head = head->batch_head;
973 
974 		/*
975 		 * at this point, head's BATCH_READY could be cleared, but we
976 		 * can still add the stripe to batch list
977 		 */
978 		list_add(&sh->batch_list, &head->batch_list);
979 		spin_unlock(&head->batch_head->batch_lock);
980 	} else {
981 		head->batch_head = head;
982 		sh->batch_head = head->batch_head;
983 		spin_lock(&head->batch_lock);
984 		list_add_tail(&sh->batch_list, &head->batch_list);
985 		spin_unlock(&head->batch_lock);
986 	}
987 
988 	if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
989 		if (atomic_dec_return(&conf->preread_active_stripes)
990 		    < IO_THRESHOLD)
991 			md_wakeup_thread(conf->mddev->thread);
992 
993 	if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
994 		int seq = sh->bm_seq;
995 		if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
996 		    sh->batch_head->bm_seq > seq)
997 			seq = sh->batch_head->bm_seq;
998 		set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
999 		sh->batch_head->bm_seq = seq;
1000 	}
1001 
1002 	atomic_inc(&sh->count);
1003 unlock_out:
1004 	unlock_two_stripes(head, sh);
1005 out:
1006 	raid5_release_stripe(head);
1007 }
1008 
1009 /* Determine if 'data_offset' or 'new_data_offset' should be used
1010  * in this stripe_head.
1011  */
1012 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
1013 {
1014 	sector_t progress = conf->reshape_progress;
1015 	/* Need a memory barrier to make sure we see the value
1016 	 * of conf->generation, or ->data_offset that was set before
1017 	 * reshape_progress was updated.
1018 	 */
1019 	smp_rmb();
1020 	if (progress == MaxSector)
1021 		return 0;
1022 	if (sh->generation == conf->generation - 1)
1023 		return 0;
1024 	/* We are in a reshape, and this is a new-generation stripe,
1025 	 * so use new_data_offset.
1026 	 */
1027 	return 1;
1028 }
1029 
1030 static void dispatch_bio_list(struct bio_list *tmp)
1031 {
1032 	struct bio *bio;
1033 
1034 	while ((bio = bio_list_pop(tmp)))
1035 		submit_bio_noacct(bio);
1036 }
1037 
1038 static int cmp_stripe(void *priv, const struct list_head *a,
1039 		      const struct list_head *b)
1040 {
1041 	const struct r5pending_data *da = list_entry(a,
1042 				struct r5pending_data, sibling);
1043 	const struct r5pending_data *db = list_entry(b,
1044 				struct r5pending_data, sibling);
1045 	if (da->sector > db->sector)
1046 		return 1;
1047 	if (da->sector < db->sector)
1048 		return -1;
1049 	return 0;
1050 }
1051 
1052 static void dispatch_defer_bios(struct r5conf *conf, int target,
1053 				struct bio_list *list)
1054 {
1055 	struct r5pending_data *data;
1056 	struct list_head *first, *next = NULL;
1057 	int cnt = 0;
1058 
1059 	if (conf->pending_data_cnt == 0)
1060 		return;
1061 
1062 	list_sort(NULL, &conf->pending_list, cmp_stripe);
1063 
1064 	first = conf->pending_list.next;
1065 
1066 	/* temporarily move the head */
1067 	if (conf->next_pending_data)
1068 		list_move_tail(&conf->pending_list,
1069 				&conf->next_pending_data->sibling);
1070 
1071 	while (!list_empty(&conf->pending_list)) {
1072 		data = list_first_entry(&conf->pending_list,
1073 			struct r5pending_data, sibling);
1074 		if (&data->sibling == first)
1075 			first = data->sibling.next;
1076 		next = data->sibling.next;
1077 
1078 		bio_list_merge(list, &data->bios);
1079 		list_move(&data->sibling, &conf->free_list);
1080 		cnt++;
1081 		if (cnt >= target)
1082 			break;
1083 	}
1084 	conf->pending_data_cnt -= cnt;
1085 	BUG_ON(conf->pending_data_cnt < 0 || cnt < target);
1086 
1087 	if (next != &conf->pending_list)
1088 		conf->next_pending_data = list_entry(next,
1089 				struct r5pending_data, sibling);
1090 	else
1091 		conf->next_pending_data = NULL;
1092 	/* list isn't empty */
1093 	if (first != &conf->pending_list)
1094 		list_move_tail(&conf->pending_list, first);
1095 }
1096 
1097 static void flush_deferred_bios(struct r5conf *conf)
1098 {
1099 	struct bio_list tmp = BIO_EMPTY_LIST;
1100 
1101 	if (conf->pending_data_cnt == 0)
1102 		return;
1103 
1104 	spin_lock(&conf->pending_bios_lock);
1105 	dispatch_defer_bios(conf, conf->pending_data_cnt, &tmp);
1106 	BUG_ON(conf->pending_data_cnt != 0);
1107 	spin_unlock(&conf->pending_bios_lock);
1108 
1109 	dispatch_bio_list(&tmp);
1110 }
1111 
1112 static void defer_issue_bios(struct r5conf *conf, sector_t sector,
1113 				struct bio_list *bios)
1114 {
1115 	struct bio_list tmp = BIO_EMPTY_LIST;
1116 	struct r5pending_data *ent;
1117 
1118 	spin_lock(&conf->pending_bios_lock);
1119 	ent = list_first_entry(&conf->free_list, struct r5pending_data,
1120 							sibling);
1121 	list_move_tail(&ent->sibling, &conf->pending_list);
1122 	ent->sector = sector;
1123 	bio_list_init(&ent->bios);
1124 	bio_list_merge(&ent->bios, bios);
1125 	conf->pending_data_cnt++;
1126 	if (conf->pending_data_cnt >= PENDING_IO_MAX)
1127 		dispatch_defer_bios(conf, PENDING_IO_ONE_FLUSH, &tmp);
1128 
1129 	spin_unlock(&conf->pending_bios_lock);
1130 
1131 	dispatch_bio_list(&tmp);
1132 }
1133 
1134 static void
1135 raid5_end_read_request(struct bio *bi);
1136 static void
1137 raid5_end_write_request(struct bio *bi);
1138 
1139 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
1140 {
1141 	struct r5conf *conf = sh->raid_conf;
1142 	int i, disks = sh->disks;
1143 	struct stripe_head *head_sh = sh;
1144 	struct bio_list pending_bios = BIO_EMPTY_LIST;
1145 	struct r5dev *dev;
1146 	bool should_defer;
1147 
1148 	might_sleep();
1149 
1150 	if (log_stripe(sh, s) == 0)
1151 		return;
1152 
1153 	should_defer = conf->batch_bio_dispatch && conf->group_cnt;
1154 
1155 	for (i = disks; i--; ) {
1156 		enum req_op op;
1157 		blk_opf_t op_flags = 0;
1158 		int replace_only = 0;
1159 		struct bio *bi, *rbi;
1160 		struct md_rdev *rdev, *rrdev = NULL;
1161 
1162 		sh = head_sh;
1163 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
1164 			op = REQ_OP_WRITE;
1165 			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
1166 				op_flags = REQ_FUA;
1167 			if (test_bit(R5_Discard, &sh->dev[i].flags))
1168 				op = REQ_OP_DISCARD;
1169 		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1170 			op = REQ_OP_READ;
1171 		else if (test_and_clear_bit(R5_WantReplace,
1172 					    &sh->dev[i].flags)) {
1173 			op = REQ_OP_WRITE;
1174 			replace_only = 1;
1175 		} else
1176 			continue;
1177 		if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
1178 			op_flags |= REQ_SYNC;
1179 
1180 again:
1181 		dev = &sh->dev[i];
1182 		bi = &dev->req;
1183 		rbi = &dev->rreq; /* For writing to replacement */
1184 
1185 		rdev = conf->disks[i].rdev;
1186 		rrdev = conf->disks[i].replacement;
1187 		if (op_is_write(op)) {
1188 			if (replace_only)
1189 				rdev = NULL;
1190 			if (rdev == rrdev)
1191 				/* We raced and saw duplicates */
1192 				rrdev = NULL;
1193 		} else {
1194 			if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
1195 				rdev = rrdev;
1196 			rrdev = NULL;
1197 		}
1198 
1199 		if (rdev && test_bit(Faulty, &rdev->flags))
1200 			rdev = NULL;
1201 		if (rdev)
1202 			atomic_inc(&rdev->nr_pending);
1203 		if (rrdev && test_bit(Faulty, &rrdev->flags))
1204 			rrdev = NULL;
1205 		if (rrdev)
1206 			atomic_inc(&rrdev->nr_pending);
1207 
1208 		/* We have already checked bad blocks for reads.  Now
1209 		 * need to check for writes.  We never accept write errors
1210 		 * on the replacement, so we don't to check rrdev.
1211 		 */
1212 		while (op_is_write(op) && rdev &&
1213 		       test_bit(WriteErrorSeen, &rdev->flags)) {
1214 			int bad = rdev_has_badblock(rdev, sh->sector,
1215 						    RAID5_STRIPE_SECTORS(conf));
1216 			if (!bad)
1217 				break;
1218 
1219 			if (bad < 0) {
1220 				set_bit(BlockedBadBlocks, &rdev->flags);
1221 				if (!conf->mddev->external &&
1222 				    conf->mddev->sb_flags) {
1223 					/* It is very unlikely, but we might
1224 					 * still need to write out the
1225 					 * bad block log - better give it
1226 					 * a chance*/
1227 					md_check_recovery(conf->mddev);
1228 				}
1229 				/*
1230 				 * Because md_wait_for_blocked_rdev
1231 				 * will dec nr_pending, we must
1232 				 * increment it first.
1233 				 */
1234 				atomic_inc(&rdev->nr_pending);
1235 				md_wait_for_blocked_rdev(rdev, conf->mddev);
1236 			} else {
1237 				/* Acknowledged bad block - skip the write */
1238 				rdev_dec_pending(rdev, conf->mddev);
1239 				rdev = NULL;
1240 			}
1241 		}
1242 
1243 		if (rdev) {
1244 			if (s->syncing || s->expanding || s->expanded
1245 			    || s->replacing)
1246 				md_sync_acct(rdev->bdev, RAID5_STRIPE_SECTORS(conf));
1247 
1248 			set_bit(STRIPE_IO_STARTED, &sh->state);
1249 
1250 			bio_init(bi, rdev->bdev, &dev->vec, 1, op | op_flags);
1251 			bi->bi_end_io = op_is_write(op)
1252 				? raid5_end_write_request
1253 				: raid5_end_read_request;
1254 			bi->bi_private = sh;
1255 
1256 			pr_debug("%s: for %llu schedule op %d on disc %d\n",
1257 				__func__, (unsigned long long)sh->sector,
1258 				bi->bi_opf, i);
1259 			atomic_inc(&sh->count);
1260 			if (sh != head_sh)
1261 				atomic_inc(&head_sh->count);
1262 			if (use_new_offset(conf, sh))
1263 				bi->bi_iter.bi_sector = (sh->sector
1264 						 + rdev->new_data_offset);
1265 			else
1266 				bi->bi_iter.bi_sector = (sh->sector
1267 						 + rdev->data_offset);
1268 			if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1269 				bi->bi_opf |= REQ_NOMERGE;
1270 
1271 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1272 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1273 
1274 			if (!op_is_write(op) &&
1275 			    test_bit(R5_InJournal, &sh->dev[i].flags))
1276 				/*
1277 				 * issuing read for a page in journal, this
1278 				 * must be preparing for prexor in rmw; read
1279 				 * the data into orig_page
1280 				 */
1281 				sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
1282 			else
1283 				sh->dev[i].vec.bv_page = sh->dev[i].page;
1284 			bi->bi_vcnt = 1;
1285 			bi->bi_io_vec[0].bv_len = RAID5_STRIPE_SIZE(conf);
1286 			bi->bi_io_vec[0].bv_offset = sh->dev[i].offset;
1287 			bi->bi_iter.bi_size = RAID5_STRIPE_SIZE(conf);
1288 			/*
1289 			 * If this is discard request, set bi_vcnt 0. We don't
1290 			 * want to confuse SCSI because SCSI will replace payload
1291 			 */
1292 			if (op == REQ_OP_DISCARD)
1293 				bi->bi_vcnt = 0;
1294 			if (rrdev)
1295 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1296 
1297 			mddev_trace_remap(conf->mddev, bi, sh->dev[i].sector);
1298 			if (should_defer && op_is_write(op))
1299 				bio_list_add(&pending_bios, bi);
1300 			else
1301 				submit_bio_noacct(bi);
1302 		}
1303 		if (rrdev) {
1304 			if (s->syncing || s->expanding || s->expanded
1305 			    || s->replacing)
1306 				md_sync_acct(rrdev->bdev, RAID5_STRIPE_SECTORS(conf));
1307 
1308 			set_bit(STRIPE_IO_STARTED, &sh->state);
1309 
1310 			bio_init(rbi, rrdev->bdev, &dev->rvec, 1, op | op_flags);
1311 			BUG_ON(!op_is_write(op));
1312 			rbi->bi_end_io = raid5_end_write_request;
1313 			rbi->bi_private = sh;
1314 
1315 			pr_debug("%s: for %llu schedule op %d on "
1316 				 "replacement disc %d\n",
1317 				__func__, (unsigned long long)sh->sector,
1318 				rbi->bi_opf, i);
1319 			atomic_inc(&sh->count);
1320 			if (sh != head_sh)
1321 				atomic_inc(&head_sh->count);
1322 			if (use_new_offset(conf, sh))
1323 				rbi->bi_iter.bi_sector = (sh->sector
1324 						  + rrdev->new_data_offset);
1325 			else
1326 				rbi->bi_iter.bi_sector = (sh->sector
1327 						  + rrdev->data_offset);
1328 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1329 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1330 			sh->dev[i].rvec.bv_page = sh->dev[i].page;
1331 			rbi->bi_vcnt = 1;
1332 			rbi->bi_io_vec[0].bv_len = RAID5_STRIPE_SIZE(conf);
1333 			rbi->bi_io_vec[0].bv_offset = sh->dev[i].offset;
1334 			rbi->bi_iter.bi_size = RAID5_STRIPE_SIZE(conf);
1335 			/*
1336 			 * If this is discard request, set bi_vcnt 0. We don't
1337 			 * want to confuse SCSI because SCSI will replace payload
1338 			 */
1339 			if (op == REQ_OP_DISCARD)
1340 				rbi->bi_vcnt = 0;
1341 			mddev_trace_remap(conf->mddev, rbi, sh->dev[i].sector);
1342 			if (should_defer && op_is_write(op))
1343 				bio_list_add(&pending_bios, rbi);
1344 			else
1345 				submit_bio_noacct(rbi);
1346 		}
1347 		if (!rdev && !rrdev) {
1348 			if (op_is_write(op))
1349 				set_bit(STRIPE_DEGRADED, &sh->state);
1350 			pr_debug("skip op %d on disc %d for sector %llu\n",
1351 				bi->bi_opf, i, (unsigned long long)sh->sector);
1352 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
1353 			set_bit(STRIPE_HANDLE, &sh->state);
1354 		}
1355 
1356 		if (!head_sh->batch_head)
1357 			continue;
1358 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1359 				      batch_list);
1360 		if (sh != head_sh)
1361 			goto again;
1362 	}
1363 
1364 	if (should_defer && !bio_list_empty(&pending_bios))
1365 		defer_issue_bios(conf, head_sh->sector, &pending_bios);
1366 }
1367 
1368 static struct dma_async_tx_descriptor *
1369 async_copy_data(int frombio, struct bio *bio, struct page **page,
1370 	unsigned int poff, sector_t sector, struct dma_async_tx_descriptor *tx,
1371 	struct stripe_head *sh, int no_skipcopy)
1372 {
1373 	struct bio_vec bvl;
1374 	struct bvec_iter iter;
1375 	struct page *bio_page;
1376 	int page_offset;
1377 	struct async_submit_ctl submit;
1378 	enum async_tx_flags flags = 0;
1379 	struct r5conf *conf = sh->raid_conf;
1380 
1381 	if (bio->bi_iter.bi_sector >= sector)
1382 		page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1383 	else
1384 		page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1385 
1386 	if (frombio)
1387 		flags |= ASYNC_TX_FENCE;
1388 	init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1389 
1390 	bio_for_each_segment(bvl, bio, iter) {
1391 		int len = bvl.bv_len;
1392 		int clen;
1393 		int b_offset = 0;
1394 
1395 		if (page_offset < 0) {
1396 			b_offset = -page_offset;
1397 			page_offset += b_offset;
1398 			len -= b_offset;
1399 		}
1400 
1401 		if (len > 0 && page_offset + len > RAID5_STRIPE_SIZE(conf))
1402 			clen = RAID5_STRIPE_SIZE(conf) - page_offset;
1403 		else
1404 			clen = len;
1405 
1406 		if (clen > 0) {
1407 			b_offset += bvl.bv_offset;
1408 			bio_page = bvl.bv_page;
1409 			if (frombio) {
1410 				if (conf->skip_copy &&
1411 				    b_offset == 0 && page_offset == 0 &&
1412 				    clen == RAID5_STRIPE_SIZE(conf) &&
1413 				    !no_skipcopy)
1414 					*page = bio_page;
1415 				else
1416 					tx = async_memcpy(*page, bio_page, page_offset + poff,
1417 						  b_offset, clen, &submit);
1418 			} else
1419 				tx = async_memcpy(bio_page, *page, b_offset,
1420 						  page_offset + poff, clen, &submit);
1421 		}
1422 		/* chain the operations */
1423 		submit.depend_tx = tx;
1424 
1425 		if (clen < len) /* hit end of page */
1426 			break;
1427 		page_offset +=  len;
1428 	}
1429 
1430 	return tx;
1431 }
1432 
1433 static void ops_complete_biofill(void *stripe_head_ref)
1434 {
1435 	struct stripe_head *sh = stripe_head_ref;
1436 	int i;
1437 	struct r5conf *conf = sh->raid_conf;
1438 
1439 	pr_debug("%s: stripe %llu\n", __func__,
1440 		(unsigned long long)sh->sector);
1441 
1442 	/* clear completed biofills */
1443 	for (i = sh->disks; i--; ) {
1444 		struct r5dev *dev = &sh->dev[i];
1445 
1446 		/* acknowledge completion of a biofill operation */
1447 		/* and check if we need to reply to a read request,
1448 		 * new R5_Wantfill requests are held off until
1449 		 * !STRIPE_BIOFILL_RUN
1450 		 */
1451 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1452 			struct bio *rbi, *rbi2;
1453 
1454 			BUG_ON(!dev->read);
1455 			rbi = dev->read;
1456 			dev->read = NULL;
1457 			while (rbi && rbi->bi_iter.bi_sector <
1458 				dev->sector + RAID5_STRIPE_SECTORS(conf)) {
1459 				rbi2 = r5_next_bio(conf, rbi, dev->sector);
1460 				bio_endio(rbi);
1461 				rbi = rbi2;
1462 			}
1463 		}
1464 	}
1465 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1466 
1467 	set_bit(STRIPE_HANDLE, &sh->state);
1468 	raid5_release_stripe(sh);
1469 }
1470 
1471 static void ops_run_biofill(struct stripe_head *sh)
1472 {
1473 	struct dma_async_tx_descriptor *tx = NULL;
1474 	struct async_submit_ctl submit;
1475 	int i;
1476 	struct r5conf *conf = sh->raid_conf;
1477 
1478 	BUG_ON(sh->batch_head);
1479 	pr_debug("%s: stripe %llu\n", __func__,
1480 		(unsigned long long)sh->sector);
1481 
1482 	for (i = sh->disks; i--; ) {
1483 		struct r5dev *dev = &sh->dev[i];
1484 		if (test_bit(R5_Wantfill, &dev->flags)) {
1485 			struct bio *rbi;
1486 			spin_lock_irq(&sh->stripe_lock);
1487 			dev->read = rbi = dev->toread;
1488 			dev->toread = NULL;
1489 			spin_unlock_irq(&sh->stripe_lock);
1490 			while (rbi && rbi->bi_iter.bi_sector <
1491 				dev->sector + RAID5_STRIPE_SECTORS(conf)) {
1492 				tx = async_copy_data(0, rbi, &dev->page,
1493 						     dev->offset,
1494 						     dev->sector, tx, sh, 0);
1495 				rbi = r5_next_bio(conf, rbi, dev->sector);
1496 			}
1497 		}
1498 	}
1499 
1500 	atomic_inc(&sh->count);
1501 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1502 	async_trigger_callback(&submit);
1503 }
1504 
1505 static void mark_target_uptodate(struct stripe_head *sh, int target)
1506 {
1507 	struct r5dev *tgt;
1508 
1509 	if (target < 0)
1510 		return;
1511 
1512 	tgt = &sh->dev[target];
1513 	set_bit(R5_UPTODATE, &tgt->flags);
1514 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1515 	clear_bit(R5_Wantcompute, &tgt->flags);
1516 }
1517 
1518 static void ops_complete_compute(void *stripe_head_ref)
1519 {
1520 	struct stripe_head *sh = stripe_head_ref;
1521 
1522 	pr_debug("%s: stripe %llu\n", __func__,
1523 		(unsigned long long)sh->sector);
1524 
1525 	/* mark the computed target(s) as uptodate */
1526 	mark_target_uptodate(sh, sh->ops.target);
1527 	mark_target_uptodate(sh, sh->ops.target2);
1528 
1529 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1530 	if (sh->check_state == check_state_compute_run)
1531 		sh->check_state = check_state_compute_result;
1532 	set_bit(STRIPE_HANDLE, &sh->state);
1533 	raid5_release_stripe(sh);
1534 }
1535 
1536 /* return a pointer to the address conversion region of the scribble buffer */
1537 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1538 {
1539 	return percpu->scribble + i * percpu->scribble_obj_size;
1540 }
1541 
1542 /* return a pointer to the address conversion region of the scribble buffer */
1543 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1544 				 struct raid5_percpu *percpu, int i)
1545 {
1546 	return (void *) (to_addr_page(percpu, i) + sh->disks + 2);
1547 }
1548 
1549 /*
1550  * Return a pointer to record offset address.
1551  */
1552 static unsigned int *
1553 to_addr_offs(struct stripe_head *sh, struct raid5_percpu *percpu)
1554 {
1555 	return (unsigned int *) (to_addr_conv(sh, percpu, 0) + sh->disks + 2);
1556 }
1557 
1558 static struct dma_async_tx_descriptor *
1559 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1560 {
1561 	int disks = sh->disks;
1562 	struct page **xor_srcs = to_addr_page(percpu, 0);
1563 	unsigned int *off_srcs = to_addr_offs(sh, percpu);
1564 	int target = sh->ops.target;
1565 	struct r5dev *tgt = &sh->dev[target];
1566 	struct page *xor_dest = tgt->page;
1567 	unsigned int off_dest = tgt->offset;
1568 	int count = 0;
1569 	struct dma_async_tx_descriptor *tx;
1570 	struct async_submit_ctl submit;
1571 	int i;
1572 
1573 	BUG_ON(sh->batch_head);
1574 
1575 	pr_debug("%s: stripe %llu block: %d\n",
1576 		__func__, (unsigned long long)sh->sector, target);
1577 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1578 
1579 	for (i = disks; i--; ) {
1580 		if (i != target) {
1581 			off_srcs[count] = sh->dev[i].offset;
1582 			xor_srcs[count++] = sh->dev[i].page;
1583 		}
1584 	}
1585 
1586 	atomic_inc(&sh->count);
1587 
1588 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1589 			  ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1590 	if (unlikely(count == 1))
1591 		tx = async_memcpy(xor_dest, xor_srcs[0], off_dest, off_srcs[0],
1592 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1593 	else
1594 		tx = async_xor_offs(xor_dest, off_dest, xor_srcs, off_srcs, count,
1595 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1596 
1597 	return tx;
1598 }
1599 
1600 /* set_syndrome_sources - populate source buffers for gen_syndrome
1601  * @srcs - (struct page *) array of size sh->disks
1602  * @offs - (unsigned int) array of offset for each page
1603  * @sh - stripe_head to parse
1604  *
1605  * Populates srcs in proper layout order for the stripe and returns the
1606  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1607  * destination buffer is recorded in srcs[count] and the Q destination
1608  * is recorded in srcs[count+1]].
1609  */
1610 static int set_syndrome_sources(struct page **srcs,
1611 				unsigned int *offs,
1612 				struct stripe_head *sh,
1613 				int srctype)
1614 {
1615 	int disks = sh->disks;
1616 	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1617 	int d0_idx = raid6_d0(sh);
1618 	int count;
1619 	int i;
1620 
1621 	for (i = 0; i < disks; i++)
1622 		srcs[i] = NULL;
1623 
1624 	count = 0;
1625 	i = d0_idx;
1626 	do {
1627 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1628 		struct r5dev *dev = &sh->dev[i];
1629 
1630 		if (i == sh->qd_idx || i == sh->pd_idx ||
1631 		    (srctype == SYNDROME_SRC_ALL) ||
1632 		    (srctype == SYNDROME_SRC_WANT_DRAIN &&
1633 		     (test_bit(R5_Wantdrain, &dev->flags) ||
1634 		      test_bit(R5_InJournal, &dev->flags))) ||
1635 		    (srctype == SYNDROME_SRC_WRITTEN &&
1636 		     (dev->written ||
1637 		      test_bit(R5_InJournal, &dev->flags)))) {
1638 			if (test_bit(R5_InJournal, &dev->flags))
1639 				srcs[slot] = sh->dev[i].orig_page;
1640 			else
1641 				srcs[slot] = sh->dev[i].page;
1642 			/*
1643 			 * For R5_InJournal, PAGE_SIZE must be 4KB and will
1644 			 * not shared page. In that case, dev[i].offset
1645 			 * is 0.
1646 			 */
1647 			offs[slot] = sh->dev[i].offset;
1648 		}
1649 		i = raid6_next_disk(i, disks);
1650 	} while (i != d0_idx);
1651 
1652 	return syndrome_disks;
1653 }
1654 
1655 static struct dma_async_tx_descriptor *
1656 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1657 {
1658 	int disks = sh->disks;
1659 	struct page **blocks = to_addr_page(percpu, 0);
1660 	unsigned int *offs = to_addr_offs(sh, percpu);
1661 	int target;
1662 	int qd_idx = sh->qd_idx;
1663 	struct dma_async_tx_descriptor *tx;
1664 	struct async_submit_ctl submit;
1665 	struct r5dev *tgt;
1666 	struct page *dest;
1667 	unsigned int dest_off;
1668 	int i;
1669 	int count;
1670 
1671 	BUG_ON(sh->batch_head);
1672 	if (sh->ops.target < 0)
1673 		target = sh->ops.target2;
1674 	else if (sh->ops.target2 < 0)
1675 		target = sh->ops.target;
1676 	else
1677 		/* we should only have one valid target */
1678 		BUG();
1679 	BUG_ON(target < 0);
1680 	pr_debug("%s: stripe %llu block: %d\n",
1681 		__func__, (unsigned long long)sh->sector, target);
1682 
1683 	tgt = &sh->dev[target];
1684 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1685 	dest = tgt->page;
1686 	dest_off = tgt->offset;
1687 
1688 	atomic_inc(&sh->count);
1689 
1690 	if (target == qd_idx) {
1691 		count = set_syndrome_sources(blocks, offs, sh, SYNDROME_SRC_ALL);
1692 		blocks[count] = NULL; /* regenerating p is not necessary */
1693 		BUG_ON(blocks[count+1] != dest); /* q should already be set */
1694 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1695 				  ops_complete_compute, sh,
1696 				  to_addr_conv(sh, percpu, 0));
1697 		tx = async_gen_syndrome(blocks, offs, count+2,
1698 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1699 	} else {
1700 		/* Compute any data- or p-drive using XOR */
1701 		count = 0;
1702 		for (i = disks; i-- ; ) {
1703 			if (i == target || i == qd_idx)
1704 				continue;
1705 			offs[count] = sh->dev[i].offset;
1706 			blocks[count++] = sh->dev[i].page;
1707 		}
1708 
1709 		init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1710 				  NULL, ops_complete_compute, sh,
1711 				  to_addr_conv(sh, percpu, 0));
1712 		tx = async_xor_offs(dest, dest_off, blocks, offs, count,
1713 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1714 	}
1715 
1716 	return tx;
1717 }
1718 
1719 static struct dma_async_tx_descriptor *
1720 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1721 {
1722 	int i, count, disks = sh->disks;
1723 	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1724 	int d0_idx = raid6_d0(sh);
1725 	int faila = -1, failb = -1;
1726 	int target = sh->ops.target;
1727 	int target2 = sh->ops.target2;
1728 	struct r5dev *tgt = &sh->dev[target];
1729 	struct r5dev *tgt2 = &sh->dev[target2];
1730 	struct dma_async_tx_descriptor *tx;
1731 	struct page **blocks = to_addr_page(percpu, 0);
1732 	unsigned int *offs = to_addr_offs(sh, percpu);
1733 	struct async_submit_ctl submit;
1734 
1735 	BUG_ON(sh->batch_head);
1736 	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1737 		 __func__, (unsigned long long)sh->sector, target, target2);
1738 	BUG_ON(target < 0 || target2 < 0);
1739 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1740 	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1741 
1742 	/* we need to open-code set_syndrome_sources to handle the
1743 	 * slot number conversion for 'faila' and 'failb'
1744 	 */
1745 	for (i = 0; i < disks ; i++) {
1746 		offs[i] = 0;
1747 		blocks[i] = NULL;
1748 	}
1749 	count = 0;
1750 	i = d0_idx;
1751 	do {
1752 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1753 
1754 		offs[slot] = sh->dev[i].offset;
1755 		blocks[slot] = sh->dev[i].page;
1756 
1757 		if (i == target)
1758 			faila = slot;
1759 		if (i == target2)
1760 			failb = slot;
1761 		i = raid6_next_disk(i, disks);
1762 	} while (i != d0_idx);
1763 
1764 	BUG_ON(faila == failb);
1765 	if (failb < faila)
1766 		swap(faila, failb);
1767 	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1768 		 __func__, (unsigned long long)sh->sector, faila, failb);
1769 
1770 	atomic_inc(&sh->count);
1771 
1772 	if (failb == syndrome_disks+1) {
1773 		/* Q disk is one of the missing disks */
1774 		if (faila == syndrome_disks) {
1775 			/* Missing P+Q, just recompute */
1776 			init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1777 					  ops_complete_compute, sh,
1778 					  to_addr_conv(sh, percpu, 0));
1779 			return async_gen_syndrome(blocks, offs, syndrome_disks+2,
1780 						  RAID5_STRIPE_SIZE(sh->raid_conf),
1781 						  &submit);
1782 		} else {
1783 			struct page *dest;
1784 			unsigned int dest_off;
1785 			int data_target;
1786 			int qd_idx = sh->qd_idx;
1787 
1788 			/* Missing D+Q: recompute D from P, then recompute Q */
1789 			if (target == qd_idx)
1790 				data_target = target2;
1791 			else
1792 				data_target = target;
1793 
1794 			count = 0;
1795 			for (i = disks; i-- ; ) {
1796 				if (i == data_target || i == qd_idx)
1797 					continue;
1798 				offs[count] = sh->dev[i].offset;
1799 				blocks[count++] = sh->dev[i].page;
1800 			}
1801 			dest = sh->dev[data_target].page;
1802 			dest_off = sh->dev[data_target].offset;
1803 			init_async_submit(&submit,
1804 					  ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1805 					  NULL, NULL, NULL,
1806 					  to_addr_conv(sh, percpu, 0));
1807 			tx = async_xor_offs(dest, dest_off, blocks, offs, count,
1808 				       RAID5_STRIPE_SIZE(sh->raid_conf),
1809 				       &submit);
1810 
1811 			count = set_syndrome_sources(blocks, offs, sh, SYNDROME_SRC_ALL);
1812 			init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1813 					  ops_complete_compute, sh,
1814 					  to_addr_conv(sh, percpu, 0));
1815 			return async_gen_syndrome(blocks, offs, count+2,
1816 						  RAID5_STRIPE_SIZE(sh->raid_conf),
1817 						  &submit);
1818 		}
1819 	} else {
1820 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1821 				  ops_complete_compute, sh,
1822 				  to_addr_conv(sh, percpu, 0));
1823 		if (failb == syndrome_disks) {
1824 			/* We're missing D+P. */
1825 			return async_raid6_datap_recov(syndrome_disks+2,
1826 						RAID5_STRIPE_SIZE(sh->raid_conf),
1827 						faila,
1828 						blocks, offs, &submit);
1829 		} else {
1830 			/* We're missing D+D. */
1831 			return async_raid6_2data_recov(syndrome_disks+2,
1832 						RAID5_STRIPE_SIZE(sh->raid_conf),
1833 						faila, failb,
1834 						blocks, offs, &submit);
1835 		}
1836 	}
1837 }
1838 
1839 static void ops_complete_prexor(void *stripe_head_ref)
1840 {
1841 	struct stripe_head *sh = stripe_head_ref;
1842 
1843 	pr_debug("%s: stripe %llu\n", __func__,
1844 		(unsigned long long)sh->sector);
1845 
1846 	if (r5c_is_writeback(sh->raid_conf->log))
1847 		/*
1848 		 * raid5-cache write back uses orig_page during prexor.
1849 		 * After prexor, it is time to free orig_page
1850 		 */
1851 		r5c_release_extra_page(sh);
1852 }
1853 
1854 static struct dma_async_tx_descriptor *
1855 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1856 		struct dma_async_tx_descriptor *tx)
1857 {
1858 	int disks = sh->disks;
1859 	struct page **xor_srcs = to_addr_page(percpu, 0);
1860 	unsigned int *off_srcs = to_addr_offs(sh, percpu);
1861 	int count = 0, pd_idx = sh->pd_idx, i;
1862 	struct async_submit_ctl submit;
1863 
1864 	/* existing parity data subtracted */
1865 	unsigned int off_dest = off_srcs[count] = sh->dev[pd_idx].offset;
1866 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1867 
1868 	BUG_ON(sh->batch_head);
1869 	pr_debug("%s: stripe %llu\n", __func__,
1870 		(unsigned long long)sh->sector);
1871 
1872 	for (i = disks; i--; ) {
1873 		struct r5dev *dev = &sh->dev[i];
1874 		/* Only process blocks that are known to be uptodate */
1875 		if (test_bit(R5_InJournal, &dev->flags)) {
1876 			/*
1877 			 * For this case, PAGE_SIZE must be equal to 4KB and
1878 			 * page offset is zero.
1879 			 */
1880 			off_srcs[count] = dev->offset;
1881 			xor_srcs[count++] = dev->orig_page;
1882 		} else if (test_bit(R5_Wantdrain, &dev->flags)) {
1883 			off_srcs[count] = dev->offset;
1884 			xor_srcs[count++] = dev->page;
1885 		}
1886 	}
1887 
1888 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1889 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1890 	tx = async_xor_offs(xor_dest, off_dest, xor_srcs, off_srcs, count,
1891 			RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1892 
1893 	return tx;
1894 }
1895 
1896 static struct dma_async_tx_descriptor *
1897 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1898 		struct dma_async_tx_descriptor *tx)
1899 {
1900 	struct page **blocks = to_addr_page(percpu, 0);
1901 	unsigned int *offs = to_addr_offs(sh, percpu);
1902 	int count;
1903 	struct async_submit_ctl submit;
1904 
1905 	pr_debug("%s: stripe %llu\n", __func__,
1906 		(unsigned long long)sh->sector);
1907 
1908 	count = set_syndrome_sources(blocks, offs, sh, SYNDROME_SRC_WANT_DRAIN);
1909 
1910 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1911 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1912 	tx = async_gen_syndrome(blocks, offs, count+2,
1913 			RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1914 
1915 	return tx;
1916 }
1917 
1918 static struct dma_async_tx_descriptor *
1919 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1920 {
1921 	struct r5conf *conf = sh->raid_conf;
1922 	int disks = sh->disks;
1923 	int i;
1924 	struct stripe_head *head_sh = sh;
1925 
1926 	pr_debug("%s: stripe %llu\n", __func__,
1927 		(unsigned long long)sh->sector);
1928 
1929 	for (i = disks; i--; ) {
1930 		struct r5dev *dev;
1931 		struct bio *chosen;
1932 
1933 		sh = head_sh;
1934 		if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1935 			struct bio *wbi;
1936 
1937 again:
1938 			dev = &sh->dev[i];
1939 			/*
1940 			 * clear R5_InJournal, so when rewriting a page in
1941 			 * journal, it is not skipped by r5l_log_stripe()
1942 			 */
1943 			clear_bit(R5_InJournal, &dev->flags);
1944 			spin_lock_irq(&sh->stripe_lock);
1945 			chosen = dev->towrite;
1946 			dev->towrite = NULL;
1947 			sh->overwrite_disks = 0;
1948 			BUG_ON(dev->written);
1949 			wbi = dev->written = chosen;
1950 			spin_unlock_irq(&sh->stripe_lock);
1951 			WARN_ON(dev->page != dev->orig_page);
1952 
1953 			while (wbi && wbi->bi_iter.bi_sector <
1954 				dev->sector + RAID5_STRIPE_SECTORS(conf)) {
1955 				if (wbi->bi_opf & REQ_FUA)
1956 					set_bit(R5_WantFUA, &dev->flags);
1957 				if (wbi->bi_opf & REQ_SYNC)
1958 					set_bit(R5_SyncIO, &dev->flags);
1959 				if (bio_op(wbi) == REQ_OP_DISCARD)
1960 					set_bit(R5_Discard, &dev->flags);
1961 				else {
1962 					tx = async_copy_data(1, wbi, &dev->page,
1963 							     dev->offset,
1964 							     dev->sector, tx, sh,
1965 							     r5c_is_writeback(conf->log));
1966 					if (dev->page != dev->orig_page &&
1967 					    !r5c_is_writeback(conf->log)) {
1968 						set_bit(R5_SkipCopy, &dev->flags);
1969 						clear_bit(R5_UPTODATE, &dev->flags);
1970 						clear_bit(R5_OVERWRITE, &dev->flags);
1971 					}
1972 				}
1973 				wbi = r5_next_bio(conf, wbi, dev->sector);
1974 			}
1975 
1976 			if (head_sh->batch_head) {
1977 				sh = list_first_entry(&sh->batch_list,
1978 						      struct stripe_head,
1979 						      batch_list);
1980 				if (sh == head_sh)
1981 					continue;
1982 				goto again;
1983 			}
1984 		}
1985 	}
1986 
1987 	return tx;
1988 }
1989 
1990 static void ops_complete_reconstruct(void *stripe_head_ref)
1991 {
1992 	struct stripe_head *sh = stripe_head_ref;
1993 	int disks = sh->disks;
1994 	int pd_idx = sh->pd_idx;
1995 	int qd_idx = sh->qd_idx;
1996 	int i;
1997 	bool fua = false, sync = false, discard = false;
1998 
1999 	pr_debug("%s: stripe %llu\n", __func__,
2000 		(unsigned long long)sh->sector);
2001 
2002 	for (i = disks; i--; ) {
2003 		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
2004 		sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
2005 		discard |= test_bit(R5_Discard, &sh->dev[i].flags);
2006 	}
2007 
2008 	for (i = disks; i--; ) {
2009 		struct r5dev *dev = &sh->dev[i];
2010 
2011 		if (dev->written || i == pd_idx || i == qd_idx) {
2012 			if (!discard && !test_bit(R5_SkipCopy, &dev->flags)) {
2013 				set_bit(R5_UPTODATE, &dev->flags);
2014 				if (test_bit(STRIPE_EXPAND_READY, &sh->state))
2015 					set_bit(R5_Expanded, &dev->flags);
2016 			}
2017 			if (fua)
2018 				set_bit(R5_WantFUA, &dev->flags);
2019 			if (sync)
2020 				set_bit(R5_SyncIO, &dev->flags);
2021 		}
2022 	}
2023 
2024 	if (sh->reconstruct_state == reconstruct_state_drain_run)
2025 		sh->reconstruct_state = reconstruct_state_drain_result;
2026 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
2027 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
2028 	else {
2029 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
2030 		sh->reconstruct_state = reconstruct_state_result;
2031 	}
2032 
2033 	set_bit(STRIPE_HANDLE, &sh->state);
2034 	raid5_release_stripe(sh);
2035 }
2036 
2037 static void
2038 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
2039 		     struct dma_async_tx_descriptor *tx)
2040 {
2041 	int disks = sh->disks;
2042 	struct page **xor_srcs;
2043 	unsigned int *off_srcs;
2044 	struct async_submit_ctl submit;
2045 	int count, pd_idx = sh->pd_idx, i;
2046 	struct page *xor_dest;
2047 	unsigned int off_dest;
2048 	int prexor = 0;
2049 	unsigned long flags;
2050 	int j = 0;
2051 	struct stripe_head *head_sh = sh;
2052 	int last_stripe;
2053 
2054 	pr_debug("%s: stripe %llu\n", __func__,
2055 		(unsigned long long)sh->sector);
2056 
2057 	for (i = 0; i < sh->disks; i++) {
2058 		if (pd_idx == i)
2059 			continue;
2060 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
2061 			break;
2062 	}
2063 	if (i >= sh->disks) {
2064 		atomic_inc(&sh->count);
2065 		set_bit(R5_Discard, &sh->dev[pd_idx].flags);
2066 		ops_complete_reconstruct(sh);
2067 		return;
2068 	}
2069 again:
2070 	count = 0;
2071 	xor_srcs = to_addr_page(percpu, j);
2072 	off_srcs = to_addr_offs(sh, percpu);
2073 	/* check if prexor is active which means only process blocks
2074 	 * that are part of a read-modify-write (written)
2075 	 */
2076 	if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
2077 		prexor = 1;
2078 		off_dest = off_srcs[count] = sh->dev[pd_idx].offset;
2079 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
2080 		for (i = disks; i--; ) {
2081 			struct r5dev *dev = &sh->dev[i];
2082 			if (head_sh->dev[i].written ||
2083 			    test_bit(R5_InJournal, &head_sh->dev[i].flags)) {
2084 				off_srcs[count] = dev->offset;
2085 				xor_srcs[count++] = dev->page;
2086 			}
2087 		}
2088 	} else {
2089 		xor_dest = sh->dev[pd_idx].page;
2090 		off_dest = sh->dev[pd_idx].offset;
2091 		for (i = disks; i--; ) {
2092 			struct r5dev *dev = &sh->dev[i];
2093 			if (i != pd_idx) {
2094 				off_srcs[count] = dev->offset;
2095 				xor_srcs[count++] = dev->page;
2096 			}
2097 		}
2098 	}
2099 
2100 	/* 1/ if we prexor'd then the dest is reused as a source
2101 	 * 2/ if we did not prexor then we are redoing the parity
2102 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
2103 	 * for the synchronous xor case
2104 	 */
2105 	last_stripe = !head_sh->batch_head ||
2106 		list_first_entry(&sh->batch_list,
2107 				 struct stripe_head, batch_list) == head_sh;
2108 	if (last_stripe) {
2109 		flags = ASYNC_TX_ACK |
2110 			(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
2111 
2112 		atomic_inc(&head_sh->count);
2113 		init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
2114 				  to_addr_conv(sh, percpu, j));
2115 	} else {
2116 		flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
2117 		init_async_submit(&submit, flags, tx, NULL, NULL,
2118 				  to_addr_conv(sh, percpu, j));
2119 	}
2120 
2121 	if (unlikely(count == 1))
2122 		tx = async_memcpy(xor_dest, xor_srcs[0], off_dest, off_srcs[0],
2123 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
2124 	else
2125 		tx = async_xor_offs(xor_dest, off_dest, xor_srcs, off_srcs, count,
2126 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
2127 	if (!last_stripe) {
2128 		j++;
2129 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
2130 				      batch_list);
2131 		goto again;
2132 	}
2133 }
2134 
2135 static void
2136 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
2137 		     struct dma_async_tx_descriptor *tx)
2138 {
2139 	struct async_submit_ctl submit;
2140 	struct page **blocks;
2141 	unsigned int *offs;
2142 	int count, i, j = 0;
2143 	struct stripe_head *head_sh = sh;
2144 	int last_stripe;
2145 	int synflags;
2146 	unsigned long txflags;
2147 
2148 	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
2149 
2150 	for (i = 0; i < sh->disks; i++) {
2151 		if (sh->pd_idx == i || sh->qd_idx == i)
2152 			continue;
2153 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
2154 			break;
2155 	}
2156 	if (i >= sh->disks) {
2157 		atomic_inc(&sh->count);
2158 		set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
2159 		set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
2160 		ops_complete_reconstruct(sh);
2161 		return;
2162 	}
2163 
2164 again:
2165 	blocks = to_addr_page(percpu, j);
2166 	offs = to_addr_offs(sh, percpu);
2167 
2168 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
2169 		synflags = SYNDROME_SRC_WRITTEN;
2170 		txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
2171 	} else {
2172 		synflags = SYNDROME_SRC_ALL;
2173 		txflags = ASYNC_TX_ACK;
2174 	}
2175 
2176 	count = set_syndrome_sources(blocks, offs, sh, synflags);
2177 	last_stripe = !head_sh->batch_head ||
2178 		list_first_entry(&sh->batch_list,
2179 				 struct stripe_head, batch_list) == head_sh;
2180 
2181 	if (last_stripe) {
2182 		atomic_inc(&head_sh->count);
2183 		init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
2184 				  head_sh, to_addr_conv(sh, percpu, j));
2185 	} else
2186 		init_async_submit(&submit, 0, tx, NULL, NULL,
2187 				  to_addr_conv(sh, percpu, j));
2188 	tx = async_gen_syndrome(blocks, offs, count+2,
2189 			RAID5_STRIPE_SIZE(sh->raid_conf),  &submit);
2190 	if (!last_stripe) {
2191 		j++;
2192 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
2193 				      batch_list);
2194 		goto again;
2195 	}
2196 }
2197 
2198 static void ops_complete_check(void *stripe_head_ref)
2199 {
2200 	struct stripe_head *sh = stripe_head_ref;
2201 
2202 	pr_debug("%s: stripe %llu\n", __func__,
2203 		(unsigned long long)sh->sector);
2204 
2205 	sh->check_state = check_state_check_result;
2206 	set_bit(STRIPE_HANDLE, &sh->state);
2207 	raid5_release_stripe(sh);
2208 }
2209 
2210 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
2211 {
2212 	int disks = sh->disks;
2213 	int pd_idx = sh->pd_idx;
2214 	int qd_idx = sh->qd_idx;
2215 	struct page *xor_dest;
2216 	unsigned int off_dest;
2217 	struct page **xor_srcs = to_addr_page(percpu, 0);
2218 	unsigned int *off_srcs = to_addr_offs(sh, percpu);
2219 	struct dma_async_tx_descriptor *tx;
2220 	struct async_submit_ctl submit;
2221 	int count;
2222 	int i;
2223 
2224 	pr_debug("%s: stripe %llu\n", __func__,
2225 		(unsigned long long)sh->sector);
2226 
2227 	BUG_ON(sh->batch_head);
2228 	count = 0;
2229 	xor_dest = sh->dev[pd_idx].page;
2230 	off_dest = sh->dev[pd_idx].offset;
2231 	off_srcs[count] = off_dest;
2232 	xor_srcs[count++] = xor_dest;
2233 	for (i = disks; i--; ) {
2234 		if (i == pd_idx || i == qd_idx)
2235 			continue;
2236 		off_srcs[count] = sh->dev[i].offset;
2237 		xor_srcs[count++] = sh->dev[i].page;
2238 	}
2239 
2240 	init_async_submit(&submit, 0, NULL, NULL, NULL,
2241 			  to_addr_conv(sh, percpu, 0));
2242 	tx = async_xor_val_offs(xor_dest, off_dest, xor_srcs, off_srcs, count,
2243 			   RAID5_STRIPE_SIZE(sh->raid_conf),
2244 			   &sh->ops.zero_sum_result, &submit);
2245 
2246 	atomic_inc(&sh->count);
2247 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
2248 	tx = async_trigger_callback(&submit);
2249 }
2250 
2251 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
2252 {
2253 	struct page **srcs = to_addr_page(percpu, 0);
2254 	unsigned int *offs = to_addr_offs(sh, percpu);
2255 	struct async_submit_ctl submit;
2256 	int count;
2257 
2258 	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
2259 		(unsigned long long)sh->sector, checkp);
2260 
2261 	BUG_ON(sh->batch_head);
2262 	count = set_syndrome_sources(srcs, offs, sh, SYNDROME_SRC_ALL);
2263 	if (!checkp)
2264 		srcs[count] = NULL;
2265 
2266 	atomic_inc(&sh->count);
2267 	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
2268 			  sh, to_addr_conv(sh, percpu, 0));
2269 	async_syndrome_val(srcs, offs, count+2,
2270 			   RAID5_STRIPE_SIZE(sh->raid_conf),
2271 			   &sh->ops.zero_sum_result, percpu->spare_page, 0, &submit);
2272 }
2273 
2274 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
2275 {
2276 	int overlap_clear = 0, i, disks = sh->disks;
2277 	struct dma_async_tx_descriptor *tx = NULL;
2278 	struct r5conf *conf = sh->raid_conf;
2279 	int level = conf->level;
2280 	struct raid5_percpu *percpu;
2281 
2282 	local_lock(&conf->percpu->lock);
2283 	percpu = this_cpu_ptr(conf->percpu);
2284 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
2285 		ops_run_biofill(sh);
2286 		overlap_clear++;
2287 	}
2288 
2289 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
2290 		if (level < 6)
2291 			tx = ops_run_compute5(sh, percpu);
2292 		else {
2293 			if (sh->ops.target2 < 0 || sh->ops.target < 0)
2294 				tx = ops_run_compute6_1(sh, percpu);
2295 			else
2296 				tx = ops_run_compute6_2(sh, percpu);
2297 		}
2298 		/* terminate the chain if reconstruct is not set to be run */
2299 		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
2300 			async_tx_ack(tx);
2301 	}
2302 
2303 	if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
2304 		if (level < 6)
2305 			tx = ops_run_prexor5(sh, percpu, tx);
2306 		else
2307 			tx = ops_run_prexor6(sh, percpu, tx);
2308 	}
2309 
2310 	if (test_bit(STRIPE_OP_PARTIAL_PARITY, &ops_request))
2311 		tx = ops_run_partial_parity(sh, percpu, tx);
2312 
2313 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
2314 		tx = ops_run_biodrain(sh, tx);
2315 		overlap_clear++;
2316 	}
2317 
2318 	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
2319 		if (level < 6)
2320 			ops_run_reconstruct5(sh, percpu, tx);
2321 		else
2322 			ops_run_reconstruct6(sh, percpu, tx);
2323 	}
2324 
2325 	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
2326 		if (sh->check_state == check_state_run)
2327 			ops_run_check_p(sh, percpu);
2328 		else if (sh->check_state == check_state_run_q)
2329 			ops_run_check_pq(sh, percpu, 0);
2330 		else if (sh->check_state == check_state_run_pq)
2331 			ops_run_check_pq(sh, percpu, 1);
2332 		else
2333 			BUG();
2334 	}
2335 
2336 	if (overlap_clear && !sh->batch_head) {
2337 		for (i = disks; i--; ) {
2338 			struct r5dev *dev = &sh->dev[i];
2339 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
2340 				wake_up(&sh->raid_conf->wait_for_overlap);
2341 		}
2342 	}
2343 	local_unlock(&conf->percpu->lock);
2344 }
2345 
2346 static void free_stripe(struct kmem_cache *sc, struct stripe_head *sh)
2347 {
2348 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
2349 	kfree(sh->pages);
2350 #endif
2351 	if (sh->ppl_page)
2352 		__free_page(sh->ppl_page);
2353 	kmem_cache_free(sc, sh);
2354 }
2355 
2356 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
2357 	int disks, struct r5conf *conf)
2358 {
2359 	struct stripe_head *sh;
2360 
2361 	sh = kmem_cache_zalloc(sc, gfp);
2362 	if (sh) {
2363 		spin_lock_init(&sh->stripe_lock);
2364 		spin_lock_init(&sh->batch_lock);
2365 		INIT_LIST_HEAD(&sh->batch_list);
2366 		INIT_LIST_HEAD(&sh->lru);
2367 		INIT_LIST_HEAD(&sh->r5c);
2368 		INIT_LIST_HEAD(&sh->log_list);
2369 		atomic_set(&sh->count, 1);
2370 		sh->raid_conf = conf;
2371 		sh->log_start = MaxSector;
2372 
2373 		if (raid5_has_ppl(conf)) {
2374 			sh->ppl_page = alloc_page(gfp);
2375 			if (!sh->ppl_page) {
2376 				free_stripe(sc, sh);
2377 				return NULL;
2378 			}
2379 		}
2380 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
2381 		if (init_stripe_shared_pages(sh, conf, disks)) {
2382 			free_stripe(sc, sh);
2383 			return NULL;
2384 		}
2385 #endif
2386 	}
2387 	return sh;
2388 }
2389 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2390 {
2391 	struct stripe_head *sh;
2392 
2393 	sh = alloc_stripe(conf->slab_cache, gfp, conf->pool_size, conf);
2394 	if (!sh)
2395 		return 0;
2396 
2397 	if (grow_buffers(sh, gfp)) {
2398 		shrink_buffers(sh);
2399 		free_stripe(conf->slab_cache, sh);
2400 		return 0;
2401 	}
2402 	sh->hash_lock_index =
2403 		conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2404 	/* we just created an active stripe so... */
2405 	atomic_inc(&conf->active_stripes);
2406 
2407 	raid5_release_stripe(sh);
2408 	WRITE_ONCE(conf->max_nr_stripes, conf->max_nr_stripes + 1);
2409 	return 1;
2410 }
2411 
2412 static int grow_stripes(struct r5conf *conf, int num)
2413 {
2414 	struct kmem_cache *sc;
2415 	size_t namelen = sizeof(conf->cache_name[0]);
2416 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
2417 
2418 	if (mddev_is_dm(conf->mddev))
2419 		snprintf(conf->cache_name[0], namelen,
2420 			"raid%d-%p", conf->level, conf->mddev);
2421 	else
2422 		snprintf(conf->cache_name[0], namelen,
2423 			"raid%d-%s", conf->level, mdname(conf->mddev));
2424 	snprintf(conf->cache_name[1], namelen, "%.27s-alt", conf->cache_name[0]);
2425 
2426 	conf->active_name = 0;
2427 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
2428 			       struct_size_t(struct stripe_head, dev, devs),
2429 			       0, 0, NULL);
2430 	if (!sc)
2431 		return 1;
2432 	conf->slab_cache = sc;
2433 	conf->pool_size = devs;
2434 	while (num--)
2435 		if (!grow_one_stripe(conf, GFP_KERNEL))
2436 			return 1;
2437 
2438 	return 0;
2439 }
2440 
2441 /**
2442  * scribble_alloc - allocate percpu scribble buffer for required size
2443  *		    of the scribble region
2444  * @percpu: from for_each_present_cpu() of the caller
2445  * @num: total number of disks in the array
2446  * @cnt: scribble objs count for required size of the scribble region
2447  *
2448  * The scribble buffer size must be enough to contain:
2449  * 1/ a struct page pointer for each device in the array +2
2450  * 2/ room to convert each entry in (1) to its corresponding dma
2451  *    (dma_map_page()) or page (page_address()) address.
2452  *
2453  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2454  * calculate over all devices (not just the data blocks), using zeros in place
2455  * of the P and Q blocks.
2456  */
2457 static int scribble_alloc(struct raid5_percpu *percpu,
2458 			  int num, int cnt)
2459 {
2460 	size_t obj_size =
2461 		sizeof(struct page *) * (num + 2) +
2462 		sizeof(addr_conv_t) * (num + 2) +
2463 		sizeof(unsigned int) * (num + 2);
2464 	void *scribble;
2465 
2466 	/*
2467 	 * If here is in raid array suspend context, it is in memalloc noio
2468 	 * context as well, there is no potential recursive memory reclaim
2469 	 * I/Os with the GFP_KERNEL flag.
2470 	 */
2471 	scribble = kvmalloc_array(cnt, obj_size, GFP_KERNEL);
2472 	if (!scribble)
2473 		return -ENOMEM;
2474 
2475 	kvfree(percpu->scribble);
2476 
2477 	percpu->scribble = scribble;
2478 	percpu->scribble_obj_size = obj_size;
2479 	return 0;
2480 }
2481 
2482 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2483 {
2484 	unsigned long cpu;
2485 	int err = 0;
2486 
2487 	/* Never shrink. */
2488 	if (conf->scribble_disks >= new_disks &&
2489 	    conf->scribble_sectors >= new_sectors)
2490 		return 0;
2491 
2492 	raid5_quiesce(conf->mddev, true);
2493 	cpus_read_lock();
2494 
2495 	for_each_present_cpu(cpu) {
2496 		struct raid5_percpu *percpu;
2497 
2498 		percpu = per_cpu_ptr(conf->percpu, cpu);
2499 		err = scribble_alloc(percpu, new_disks,
2500 				     new_sectors / RAID5_STRIPE_SECTORS(conf));
2501 		if (err)
2502 			break;
2503 	}
2504 
2505 	cpus_read_unlock();
2506 	raid5_quiesce(conf->mddev, false);
2507 
2508 	if (!err) {
2509 		conf->scribble_disks = new_disks;
2510 		conf->scribble_sectors = new_sectors;
2511 	}
2512 	return err;
2513 }
2514 
2515 static int resize_stripes(struct r5conf *conf, int newsize)
2516 {
2517 	/* Make all the stripes able to hold 'newsize' devices.
2518 	 * New slots in each stripe get 'page' set to a new page.
2519 	 *
2520 	 * This happens in stages:
2521 	 * 1/ create a new kmem_cache and allocate the required number of
2522 	 *    stripe_heads.
2523 	 * 2/ gather all the old stripe_heads and transfer the pages across
2524 	 *    to the new stripe_heads.  This will have the side effect of
2525 	 *    freezing the array as once all stripe_heads have been collected,
2526 	 *    no IO will be possible.  Old stripe heads are freed once their
2527 	 *    pages have been transferred over, and the old kmem_cache is
2528 	 *    freed when all stripes are done.
2529 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2530 	 *    we simple return a failure status - no need to clean anything up.
2531 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
2532 	 *    If this fails, we don't bother trying the shrink the
2533 	 *    stripe_heads down again, we just leave them as they are.
2534 	 *    As each stripe_head is processed the new one is released into
2535 	 *    active service.
2536 	 *
2537 	 * Once step2 is started, we cannot afford to wait for a write,
2538 	 * so we use GFP_NOIO allocations.
2539 	 */
2540 	struct stripe_head *osh, *nsh;
2541 	LIST_HEAD(newstripes);
2542 	struct disk_info *ndisks;
2543 	int err = 0;
2544 	struct kmem_cache *sc;
2545 	int i;
2546 	int hash, cnt;
2547 
2548 	md_allow_write(conf->mddev);
2549 
2550 	/* Step 1 */
2551 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2552 			       struct_size_t(struct stripe_head, dev, newsize),
2553 			       0, 0, NULL);
2554 	if (!sc)
2555 		return -ENOMEM;
2556 
2557 	/* Need to ensure auto-resizing doesn't interfere */
2558 	mutex_lock(&conf->cache_size_mutex);
2559 
2560 	for (i = conf->max_nr_stripes; i; i--) {
2561 		nsh = alloc_stripe(sc, GFP_KERNEL, newsize, conf);
2562 		if (!nsh)
2563 			break;
2564 
2565 		list_add(&nsh->lru, &newstripes);
2566 	}
2567 	if (i) {
2568 		/* didn't get enough, give up */
2569 		while (!list_empty(&newstripes)) {
2570 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
2571 			list_del(&nsh->lru);
2572 			free_stripe(sc, nsh);
2573 		}
2574 		kmem_cache_destroy(sc);
2575 		mutex_unlock(&conf->cache_size_mutex);
2576 		return -ENOMEM;
2577 	}
2578 	/* Step 2 - Must use GFP_NOIO now.
2579 	 * OK, we have enough stripes, start collecting inactive
2580 	 * stripes and copying them over
2581 	 */
2582 	hash = 0;
2583 	cnt = 0;
2584 	list_for_each_entry(nsh, &newstripes, lru) {
2585 		lock_device_hash_lock(conf, hash);
2586 		wait_event_cmd(conf->wait_for_stripe,
2587 				    !list_empty(conf->inactive_list + hash),
2588 				    unlock_device_hash_lock(conf, hash),
2589 				    lock_device_hash_lock(conf, hash));
2590 		osh = get_free_stripe(conf, hash);
2591 		unlock_device_hash_lock(conf, hash);
2592 
2593 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
2594 	for (i = 0; i < osh->nr_pages; i++) {
2595 		nsh->pages[i] = osh->pages[i];
2596 		osh->pages[i] = NULL;
2597 	}
2598 #endif
2599 		for(i=0; i<conf->pool_size; i++) {
2600 			nsh->dev[i].page = osh->dev[i].page;
2601 			nsh->dev[i].orig_page = osh->dev[i].page;
2602 			nsh->dev[i].offset = osh->dev[i].offset;
2603 		}
2604 		nsh->hash_lock_index = hash;
2605 		free_stripe(conf->slab_cache, osh);
2606 		cnt++;
2607 		if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2608 		    !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2609 			hash++;
2610 			cnt = 0;
2611 		}
2612 	}
2613 	kmem_cache_destroy(conf->slab_cache);
2614 
2615 	/* Step 3.
2616 	 * At this point, we are holding all the stripes so the array
2617 	 * is completely stalled, so now is a good time to resize
2618 	 * conf->disks and the scribble region
2619 	 */
2620 	ndisks = kcalloc(newsize, sizeof(struct disk_info), GFP_NOIO);
2621 	if (ndisks) {
2622 		for (i = 0; i < conf->pool_size; i++)
2623 			ndisks[i] = conf->disks[i];
2624 
2625 		for (i = conf->pool_size; i < newsize; i++) {
2626 			ndisks[i].extra_page = alloc_page(GFP_NOIO);
2627 			if (!ndisks[i].extra_page)
2628 				err = -ENOMEM;
2629 		}
2630 
2631 		if (err) {
2632 			for (i = conf->pool_size; i < newsize; i++)
2633 				if (ndisks[i].extra_page)
2634 					put_page(ndisks[i].extra_page);
2635 			kfree(ndisks);
2636 		} else {
2637 			kfree(conf->disks);
2638 			conf->disks = ndisks;
2639 		}
2640 	} else
2641 		err = -ENOMEM;
2642 
2643 	conf->slab_cache = sc;
2644 	conf->active_name = 1-conf->active_name;
2645 
2646 	/* Step 4, return new stripes to service */
2647 	while(!list_empty(&newstripes)) {
2648 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
2649 		list_del_init(&nsh->lru);
2650 
2651 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
2652 		for (i = 0; i < nsh->nr_pages; i++) {
2653 			if (nsh->pages[i])
2654 				continue;
2655 			nsh->pages[i] = alloc_page(GFP_NOIO);
2656 			if (!nsh->pages[i])
2657 				err = -ENOMEM;
2658 		}
2659 
2660 		for (i = conf->raid_disks; i < newsize; i++) {
2661 			if (nsh->dev[i].page)
2662 				continue;
2663 			nsh->dev[i].page = raid5_get_dev_page(nsh, i);
2664 			nsh->dev[i].orig_page = nsh->dev[i].page;
2665 			nsh->dev[i].offset = raid5_get_page_offset(nsh, i);
2666 		}
2667 #else
2668 		for (i=conf->raid_disks; i < newsize; i++)
2669 			if (nsh->dev[i].page == NULL) {
2670 				struct page *p = alloc_page(GFP_NOIO);
2671 				nsh->dev[i].page = p;
2672 				nsh->dev[i].orig_page = p;
2673 				nsh->dev[i].offset = 0;
2674 				if (!p)
2675 					err = -ENOMEM;
2676 			}
2677 #endif
2678 		raid5_release_stripe(nsh);
2679 	}
2680 	/* critical section pass, GFP_NOIO no longer needed */
2681 
2682 	if (!err)
2683 		conf->pool_size = newsize;
2684 	mutex_unlock(&conf->cache_size_mutex);
2685 
2686 	return err;
2687 }
2688 
2689 static int drop_one_stripe(struct r5conf *conf)
2690 {
2691 	struct stripe_head *sh;
2692 	int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2693 
2694 	spin_lock_irq(conf->hash_locks + hash);
2695 	sh = get_free_stripe(conf, hash);
2696 	spin_unlock_irq(conf->hash_locks + hash);
2697 	if (!sh)
2698 		return 0;
2699 	BUG_ON(atomic_read(&sh->count));
2700 	shrink_buffers(sh);
2701 	free_stripe(conf->slab_cache, sh);
2702 	atomic_dec(&conf->active_stripes);
2703 	WRITE_ONCE(conf->max_nr_stripes, conf->max_nr_stripes - 1);
2704 	return 1;
2705 }
2706 
2707 static void shrink_stripes(struct r5conf *conf)
2708 {
2709 	while (conf->max_nr_stripes &&
2710 	       drop_one_stripe(conf))
2711 		;
2712 
2713 	kmem_cache_destroy(conf->slab_cache);
2714 	conf->slab_cache = NULL;
2715 }
2716 
2717 static void raid5_end_read_request(struct bio * bi)
2718 {
2719 	struct stripe_head *sh = bi->bi_private;
2720 	struct r5conf *conf = sh->raid_conf;
2721 	int disks = sh->disks, i;
2722 	struct md_rdev *rdev = NULL;
2723 	sector_t s;
2724 
2725 	for (i=0 ; i<disks; i++)
2726 		if (bi == &sh->dev[i].req)
2727 			break;
2728 
2729 	pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2730 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2731 		bi->bi_status);
2732 	if (i == disks) {
2733 		BUG();
2734 		return;
2735 	}
2736 	if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2737 		/* If replacement finished while this request was outstanding,
2738 		 * 'replacement' might be NULL already.
2739 		 * In that case it moved down to 'rdev'.
2740 		 * rdev is not removed until all requests are finished.
2741 		 */
2742 		rdev = conf->disks[i].replacement;
2743 	if (!rdev)
2744 		rdev = conf->disks[i].rdev;
2745 
2746 	if (use_new_offset(conf, sh))
2747 		s = sh->sector + rdev->new_data_offset;
2748 	else
2749 		s = sh->sector + rdev->data_offset;
2750 	if (!bi->bi_status) {
2751 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
2752 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2753 			/* Note that this cannot happen on a
2754 			 * replacement device.  We just fail those on
2755 			 * any error
2756 			 */
2757 			pr_info_ratelimited(
2758 				"md/raid:%s: read error corrected (%lu sectors at %llu on %pg)\n",
2759 				mdname(conf->mddev), RAID5_STRIPE_SECTORS(conf),
2760 				(unsigned long long)s,
2761 				rdev->bdev);
2762 			atomic_add(RAID5_STRIPE_SECTORS(conf), &rdev->corrected_errors);
2763 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2764 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2765 		} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2766 			clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2767 
2768 		if (test_bit(R5_InJournal, &sh->dev[i].flags))
2769 			/*
2770 			 * end read for a page in journal, this
2771 			 * must be preparing for prexor in rmw
2772 			 */
2773 			set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
2774 
2775 		if (atomic_read(&rdev->read_errors))
2776 			atomic_set(&rdev->read_errors, 0);
2777 	} else {
2778 		int retry = 0;
2779 		int set_bad = 0;
2780 
2781 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2782 		if (!(bi->bi_status == BLK_STS_PROTECTION))
2783 			atomic_inc(&rdev->read_errors);
2784 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2785 			pr_warn_ratelimited(
2786 				"md/raid:%s: read error on replacement device (sector %llu on %pg).\n",
2787 				mdname(conf->mddev),
2788 				(unsigned long long)s,
2789 				rdev->bdev);
2790 		else if (conf->mddev->degraded >= conf->max_degraded) {
2791 			set_bad = 1;
2792 			pr_warn_ratelimited(
2793 				"md/raid:%s: read error not correctable (sector %llu on %pg).\n",
2794 				mdname(conf->mddev),
2795 				(unsigned long long)s,
2796 				rdev->bdev);
2797 		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2798 			/* Oh, no!!! */
2799 			set_bad = 1;
2800 			pr_warn_ratelimited(
2801 				"md/raid:%s: read error NOT corrected!! (sector %llu on %pg).\n",
2802 				mdname(conf->mddev),
2803 				(unsigned long long)s,
2804 				rdev->bdev);
2805 		} else if (atomic_read(&rdev->read_errors)
2806 			 > conf->max_nr_stripes) {
2807 			if (!test_bit(Faulty, &rdev->flags)) {
2808 				pr_warn("md/raid:%s: %d read_errors > %d stripes\n",
2809 				    mdname(conf->mddev),
2810 				    atomic_read(&rdev->read_errors),
2811 				    conf->max_nr_stripes);
2812 				pr_warn("md/raid:%s: Too many read errors, failing device %pg.\n",
2813 				    mdname(conf->mddev), rdev->bdev);
2814 			}
2815 		} else
2816 			retry = 1;
2817 		if (set_bad && test_bit(In_sync, &rdev->flags)
2818 		    && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2819 			retry = 1;
2820 		if (retry)
2821 			if (sh->qd_idx >= 0 && sh->pd_idx == i)
2822 				set_bit(R5_ReadError, &sh->dev[i].flags);
2823 			else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2824 				set_bit(R5_ReadError, &sh->dev[i].flags);
2825 				clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2826 			} else
2827 				set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2828 		else {
2829 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2830 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2831 			if (!(set_bad
2832 			      && test_bit(In_sync, &rdev->flags)
2833 			      && rdev_set_badblocks(
2834 				      rdev, sh->sector, RAID5_STRIPE_SECTORS(conf), 0)))
2835 				md_error(conf->mddev, rdev);
2836 		}
2837 	}
2838 	rdev_dec_pending(rdev, conf->mddev);
2839 	bio_uninit(bi);
2840 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
2841 	set_bit(STRIPE_HANDLE, &sh->state);
2842 	raid5_release_stripe(sh);
2843 }
2844 
2845 static void raid5_end_write_request(struct bio *bi)
2846 {
2847 	struct stripe_head *sh = bi->bi_private;
2848 	struct r5conf *conf = sh->raid_conf;
2849 	int disks = sh->disks, i;
2850 	struct md_rdev *rdev;
2851 	int replacement = 0;
2852 
2853 	for (i = 0 ; i < disks; i++) {
2854 		if (bi == &sh->dev[i].req) {
2855 			rdev = conf->disks[i].rdev;
2856 			break;
2857 		}
2858 		if (bi == &sh->dev[i].rreq) {
2859 			rdev = conf->disks[i].replacement;
2860 			if (rdev)
2861 				replacement = 1;
2862 			else
2863 				/* rdev was removed and 'replacement'
2864 				 * replaced it.  rdev is not removed
2865 				 * until all requests are finished.
2866 				 */
2867 				rdev = conf->disks[i].rdev;
2868 			break;
2869 		}
2870 	}
2871 	pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2872 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2873 		bi->bi_status);
2874 	if (i == disks) {
2875 		BUG();
2876 		return;
2877 	}
2878 
2879 	if (replacement) {
2880 		if (bi->bi_status)
2881 			md_error(conf->mddev, rdev);
2882 		else if (rdev_has_badblock(rdev, sh->sector,
2883 					   RAID5_STRIPE_SECTORS(conf)))
2884 			set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2885 	} else {
2886 		if (bi->bi_status) {
2887 			set_bit(STRIPE_DEGRADED, &sh->state);
2888 			set_bit(WriteErrorSeen, &rdev->flags);
2889 			set_bit(R5_WriteError, &sh->dev[i].flags);
2890 			if (!test_and_set_bit(WantReplacement, &rdev->flags))
2891 				set_bit(MD_RECOVERY_NEEDED,
2892 					&rdev->mddev->recovery);
2893 		} else if (rdev_has_badblock(rdev, sh->sector,
2894 					     RAID5_STRIPE_SECTORS(conf))) {
2895 			set_bit(R5_MadeGood, &sh->dev[i].flags);
2896 			if (test_bit(R5_ReadError, &sh->dev[i].flags))
2897 				/* That was a successful write so make
2898 				 * sure it looks like we already did
2899 				 * a re-write.
2900 				 */
2901 				set_bit(R5_ReWrite, &sh->dev[i].flags);
2902 		}
2903 	}
2904 	rdev_dec_pending(rdev, conf->mddev);
2905 
2906 	if (sh->batch_head && bi->bi_status && !replacement)
2907 		set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2908 
2909 	bio_uninit(bi);
2910 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2911 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2912 	set_bit(STRIPE_HANDLE, &sh->state);
2913 
2914 	if (sh->batch_head && sh != sh->batch_head)
2915 		raid5_release_stripe(sh->batch_head);
2916 	raid5_release_stripe(sh);
2917 }
2918 
2919 static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
2920 {
2921 	struct r5conf *conf = mddev->private;
2922 	unsigned long flags;
2923 	pr_debug("raid456: error called\n");
2924 
2925 	pr_crit("md/raid:%s: Disk failure on %pg, disabling device.\n",
2926 		mdname(mddev), rdev->bdev);
2927 
2928 	spin_lock_irqsave(&conf->device_lock, flags);
2929 	set_bit(Faulty, &rdev->flags);
2930 	clear_bit(In_sync, &rdev->flags);
2931 	mddev->degraded = raid5_calc_degraded(conf);
2932 
2933 	if (has_failed(conf)) {
2934 		set_bit(MD_BROKEN, &conf->mddev->flags);
2935 		conf->recovery_disabled = mddev->recovery_disabled;
2936 
2937 		pr_crit("md/raid:%s: Cannot continue operation (%d/%d failed).\n",
2938 			mdname(mddev), mddev->degraded, conf->raid_disks);
2939 	} else {
2940 		pr_crit("md/raid:%s: Operation continuing on %d devices.\n",
2941 			mdname(mddev), conf->raid_disks - mddev->degraded);
2942 	}
2943 
2944 	spin_unlock_irqrestore(&conf->device_lock, flags);
2945 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2946 
2947 	set_bit(Blocked, &rdev->flags);
2948 	set_mask_bits(&mddev->sb_flags, 0,
2949 		      BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
2950 	r5c_update_on_rdev_error(mddev, rdev);
2951 }
2952 
2953 /*
2954  * Input: a 'big' sector number,
2955  * Output: index of the data and parity disk, and the sector # in them.
2956  */
2957 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2958 			      int previous, int *dd_idx,
2959 			      struct stripe_head *sh)
2960 {
2961 	sector_t stripe, stripe2;
2962 	sector_t chunk_number;
2963 	unsigned int chunk_offset;
2964 	int pd_idx, qd_idx;
2965 	int ddf_layout = 0;
2966 	sector_t new_sector;
2967 	int algorithm = previous ? conf->prev_algo
2968 				 : conf->algorithm;
2969 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2970 					 : conf->chunk_sectors;
2971 	int raid_disks = previous ? conf->previous_raid_disks
2972 				  : conf->raid_disks;
2973 	int data_disks = raid_disks - conf->max_degraded;
2974 
2975 	/* First compute the information on this sector */
2976 
2977 	/*
2978 	 * Compute the chunk number and the sector offset inside the chunk
2979 	 */
2980 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
2981 	chunk_number = r_sector;
2982 
2983 	/*
2984 	 * Compute the stripe number
2985 	 */
2986 	stripe = chunk_number;
2987 	*dd_idx = sector_div(stripe, data_disks);
2988 	stripe2 = stripe;
2989 	/*
2990 	 * Select the parity disk based on the user selected algorithm.
2991 	 */
2992 	pd_idx = qd_idx = -1;
2993 	switch(conf->level) {
2994 	case 4:
2995 		pd_idx = data_disks;
2996 		break;
2997 	case 5:
2998 		switch (algorithm) {
2999 		case ALGORITHM_LEFT_ASYMMETRIC:
3000 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
3001 			if (*dd_idx >= pd_idx)
3002 				(*dd_idx)++;
3003 			break;
3004 		case ALGORITHM_RIGHT_ASYMMETRIC:
3005 			pd_idx = sector_div(stripe2, raid_disks);
3006 			if (*dd_idx >= pd_idx)
3007 				(*dd_idx)++;
3008 			break;
3009 		case ALGORITHM_LEFT_SYMMETRIC:
3010 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
3011 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
3012 			break;
3013 		case ALGORITHM_RIGHT_SYMMETRIC:
3014 			pd_idx = sector_div(stripe2, raid_disks);
3015 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
3016 			break;
3017 		case ALGORITHM_PARITY_0:
3018 			pd_idx = 0;
3019 			(*dd_idx)++;
3020 			break;
3021 		case ALGORITHM_PARITY_N:
3022 			pd_idx = data_disks;
3023 			break;
3024 		default:
3025 			BUG();
3026 		}
3027 		break;
3028 	case 6:
3029 
3030 		switch (algorithm) {
3031 		case ALGORITHM_LEFT_ASYMMETRIC:
3032 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
3033 			qd_idx = pd_idx + 1;
3034 			if (pd_idx == raid_disks-1) {
3035 				(*dd_idx)++;	/* Q D D D P */
3036 				qd_idx = 0;
3037 			} else if (*dd_idx >= pd_idx)
3038 				(*dd_idx) += 2; /* D D P Q D */
3039 			break;
3040 		case ALGORITHM_RIGHT_ASYMMETRIC:
3041 			pd_idx = sector_div(stripe2, raid_disks);
3042 			qd_idx = pd_idx + 1;
3043 			if (pd_idx == raid_disks-1) {
3044 				(*dd_idx)++;	/* Q D D D P */
3045 				qd_idx = 0;
3046 			} else if (*dd_idx >= pd_idx)
3047 				(*dd_idx) += 2; /* D D P Q D */
3048 			break;
3049 		case ALGORITHM_LEFT_SYMMETRIC:
3050 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
3051 			qd_idx = (pd_idx + 1) % raid_disks;
3052 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
3053 			break;
3054 		case ALGORITHM_RIGHT_SYMMETRIC:
3055 			pd_idx = sector_div(stripe2, raid_disks);
3056 			qd_idx = (pd_idx + 1) % raid_disks;
3057 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
3058 			break;
3059 
3060 		case ALGORITHM_PARITY_0:
3061 			pd_idx = 0;
3062 			qd_idx = 1;
3063 			(*dd_idx) += 2;
3064 			break;
3065 		case ALGORITHM_PARITY_N:
3066 			pd_idx = data_disks;
3067 			qd_idx = data_disks + 1;
3068 			break;
3069 
3070 		case ALGORITHM_ROTATING_ZERO_RESTART:
3071 			/* Exactly the same as RIGHT_ASYMMETRIC, but or
3072 			 * of blocks for computing Q is different.
3073 			 */
3074 			pd_idx = sector_div(stripe2, raid_disks);
3075 			qd_idx = pd_idx + 1;
3076 			if (pd_idx == raid_disks-1) {
3077 				(*dd_idx)++;	/* Q D D D P */
3078 				qd_idx = 0;
3079 			} else if (*dd_idx >= pd_idx)
3080 				(*dd_idx) += 2; /* D D P Q D */
3081 			ddf_layout = 1;
3082 			break;
3083 
3084 		case ALGORITHM_ROTATING_N_RESTART:
3085 			/* Same a left_asymmetric, by first stripe is
3086 			 * D D D P Q  rather than
3087 			 * Q D D D P
3088 			 */
3089 			stripe2 += 1;
3090 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
3091 			qd_idx = pd_idx + 1;
3092 			if (pd_idx == raid_disks-1) {
3093 				(*dd_idx)++;	/* Q D D D P */
3094 				qd_idx = 0;
3095 			} else if (*dd_idx >= pd_idx)
3096 				(*dd_idx) += 2; /* D D P Q D */
3097 			ddf_layout = 1;
3098 			break;
3099 
3100 		case ALGORITHM_ROTATING_N_CONTINUE:
3101 			/* Same as left_symmetric but Q is before P */
3102 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
3103 			qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
3104 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
3105 			ddf_layout = 1;
3106 			break;
3107 
3108 		case ALGORITHM_LEFT_ASYMMETRIC_6:
3109 			/* RAID5 left_asymmetric, with Q on last device */
3110 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
3111 			if (*dd_idx >= pd_idx)
3112 				(*dd_idx)++;
3113 			qd_idx = raid_disks - 1;
3114 			break;
3115 
3116 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
3117 			pd_idx = sector_div(stripe2, raid_disks-1);
3118 			if (*dd_idx >= pd_idx)
3119 				(*dd_idx)++;
3120 			qd_idx = raid_disks - 1;
3121 			break;
3122 
3123 		case ALGORITHM_LEFT_SYMMETRIC_6:
3124 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
3125 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
3126 			qd_idx = raid_disks - 1;
3127 			break;
3128 
3129 		case ALGORITHM_RIGHT_SYMMETRIC_6:
3130 			pd_idx = sector_div(stripe2, raid_disks-1);
3131 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
3132 			qd_idx = raid_disks - 1;
3133 			break;
3134 
3135 		case ALGORITHM_PARITY_0_6:
3136 			pd_idx = 0;
3137 			(*dd_idx)++;
3138 			qd_idx = raid_disks - 1;
3139 			break;
3140 
3141 		default:
3142 			BUG();
3143 		}
3144 		break;
3145 	}
3146 
3147 	if (sh) {
3148 		sh->pd_idx = pd_idx;
3149 		sh->qd_idx = qd_idx;
3150 		sh->ddf_layout = ddf_layout;
3151 	}
3152 	/*
3153 	 * Finally, compute the new sector number
3154 	 */
3155 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
3156 	return new_sector;
3157 }
3158 
3159 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
3160 {
3161 	struct r5conf *conf = sh->raid_conf;
3162 	int raid_disks = sh->disks;
3163 	int data_disks = raid_disks - conf->max_degraded;
3164 	sector_t new_sector = sh->sector, check;
3165 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
3166 					 : conf->chunk_sectors;
3167 	int algorithm = previous ? conf->prev_algo
3168 				 : conf->algorithm;
3169 	sector_t stripe;
3170 	int chunk_offset;
3171 	sector_t chunk_number;
3172 	int dummy1, dd_idx = i;
3173 	sector_t r_sector;
3174 	struct stripe_head sh2;
3175 
3176 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
3177 	stripe = new_sector;
3178 
3179 	if (i == sh->pd_idx)
3180 		return 0;
3181 	switch(conf->level) {
3182 	case 4: break;
3183 	case 5:
3184 		switch (algorithm) {
3185 		case ALGORITHM_LEFT_ASYMMETRIC:
3186 		case ALGORITHM_RIGHT_ASYMMETRIC:
3187 			if (i > sh->pd_idx)
3188 				i--;
3189 			break;
3190 		case ALGORITHM_LEFT_SYMMETRIC:
3191 		case ALGORITHM_RIGHT_SYMMETRIC:
3192 			if (i < sh->pd_idx)
3193 				i += raid_disks;
3194 			i -= (sh->pd_idx + 1);
3195 			break;
3196 		case ALGORITHM_PARITY_0:
3197 			i -= 1;
3198 			break;
3199 		case ALGORITHM_PARITY_N:
3200 			break;
3201 		default:
3202 			BUG();
3203 		}
3204 		break;
3205 	case 6:
3206 		if (i == sh->qd_idx)
3207 			return 0; /* It is the Q disk */
3208 		switch (algorithm) {
3209 		case ALGORITHM_LEFT_ASYMMETRIC:
3210 		case ALGORITHM_RIGHT_ASYMMETRIC:
3211 		case ALGORITHM_ROTATING_ZERO_RESTART:
3212 		case ALGORITHM_ROTATING_N_RESTART:
3213 			if (sh->pd_idx == raid_disks-1)
3214 				i--;	/* Q D D D P */
3215 			else if (i > sh->pd_idx)
3216 				i -= 2; /* D D P Q D */
3217 			break;
3218 		case ALGORITHM_LEFT_SYMMETRIC:
3219 		case ALGORITHM_RIGHT_SYMMETRIC:
3220 			if (sh->pd_idx == raid_disks-1)
3221 				i--; /* Q D D D P */
3222 			else {
3223 				/* D D P Q D */
3224 				if (i < sh->pd_idx)
3225 					i += raid_disks;
3226 				i -= (sh->pd_idx + 2);
3227 			}
3228 			break;
3229 		case ALGORITHM_PARITY_0:
3230 			i -= 2;
3231 			break;
3232 		case ALGORITHM_PARITY_N:
3233 			break;
3234 		case ALGORITHM_ROTATING_N_CONTINUE:
3235 			/* Like left_symmetric, but P is before Q */
3236 			if (sh->pd_idx == 0)
3237 				i--;	/* P D D D Q */
3238 			else {
3239 				/* D D Q P D */
3240 				if (i < sh->pd_idx)
3241 					i += raid_disks;
3242 				i -= (sh->pd_idx + 1);
3243 			}
3244 			break;
3245 		case ALGORITHM_LEFT_ASYMMETRIC_6:
3246 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
3247 			if (i > sh->pd_idx)
3248 				i--;
3249 			break;
3250 		case ALGORITHM_LEFT_SYMMETRIC_6:
3251 		case ALGORITHM_RIGHT_SYMMETRIC_6:
3252 			if (i < sh->pd_idx)
3253 				i += data_disks + 1;
3254 			i -= (sh->pd_idx + 1);
3255 			break;
3256 		case ALGORITHM_PARITY_0_6:
3257 			i -= 1;
3258 			break;
3259 		default:
3260 			BUG();
3261 		}
3262 		break;
3263 	}
3264 
3265 	chunk_number = stripe * data_disks + i;
3266 	r_sector = chunk_number * sectors_per_chunk + chunk_offset;
3267 
3268 	check = raid5_compute_sector(conf, r_sector,
3269 				     previous, &dummy1, &sh2);
3270 	if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
3271 		|| sh2.qd_idx != sh->qd_idx) {
3272 		pr_warn("md/raid:%s: compute_blocknr: map not correct\n",
3273 			mdname(conf->mddev));
3274 		return 0;
3275 	}
3276 	return r_sector;
3277 }
3278 
3279 /*
3280  * There are cases where we want handle_stripe_dirtying() and
3281  * schedule_reconstruction() to delay towrite to some dev of a stripe.
3282  *
3283  * This function checks whether we want to delay the towrite. Specifically,
3284  * we delay the towrite when:
3285  *
3286  *   1. degraded stripe has a non-overwrite to the missing dev, AND this
3287  *      stripe has data in journal (for other devices).
3288  *
3289  *      In this case, when reading data for the non-overwrite dev, it is
3290  *      necessary to handle complex rmw of write back cache (prexor with
3291  *      orig_page, and xor with page). To keep read path simple, we would
3292  *      like to flush data in journal to RAID disks first, so complex rmw
3293  *      is handled in the write patch (handle_stripe_dirtying).
3294  *
3295  *   2. when journal space is critical (R5C_LOG_CRITICAL=1)
3296  *
3297  *      It is important to be able to flush all stripes in raid5-cache.
3298  *      Therefore, we need reserve some space on the journal device for
3299  *      these flushes. If flush operation includes pending writes to the
3300  *      stripe, we need to reserve (conf->raid_disk + 1) pages per stripe
3301  *      for the flush out. If we exclude these pending writes from flush
3302  *      operation, we only need (conf->max_degraded + 1) pages per stripe.
3303  *      Therefore, excluding pending writes in these cases enables more
3304  *      efficient use of the journal device.
3305  *
3306  *      Note: To make sure the stripe makes progress, we only delay
3307  *      towrite for stripes with data already in journal (injournal > 0).
3308  *      When LOG_CRITICAL, stripes with injournal == 0 will be sent to
3309  *      no_space_stripes list.
3310  *
3311  *   3. during journal failure
3312  *      In journal failure, we try to flush all cached data to raid disks
3313  *      based on data in stripe cache. The array is read-only to upper
3314  *      layers, so we would skip all pending writes.
3315  *
3316  */
3317 static inline bool delay_towrite(struct r5conf *conf,
3318 				 struct r5dev *dev,
3319 				 struct stripe_head_state *s)
3320 {
3321 	/* case 1 above */
3322 	if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3323 	    !test_bit(R5_Insync, &dev->flags) && s->injournal)
3324 		return true;
3325 	/* case 2 above */
3326 	if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
3327 	    s->injournal > 0)
3328 		return true;
3329 	/* case 3 above */
3330 	if (s->log_failed && s->injournal)
3331 		return true;
3332 	return false;
3333 }
3334 
3335 static void
3336 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
3337 			 int rcw, int expand)
3338 {
3339 	int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
3340 	struct r5conf *conf = sh->raid_conf;
3341 	int level = conf->level;
3342 
3343 	if (rcw) {
3344 		/*
3345 		 * In some cases, handle_stripe_dirtying initially decided to
3346 		 * run rmw and allocates extra page for prexor. However, rcw is
3347 		 * cheaper later on. We need to free the extra page now,
3348 		 * because we won't be able to do that in ops_complete_prexor().
3349 		 */
3350 		r5c_release_extra_page(sh);
3351 
3352 		for (i = disks; i--; ) {
3353 			struct r5dev *dev = &sh->dev[i];
3354 
3355 			if (dev->towrite && !delay_towrite(conf, dev, s)) {
3356 				set_bit(R5_LOCKED, &dev->flags);
3357 				set_bit(R5_Wantdrain, &dev->flags);
3358 				if (!expand)
3359 					clear_bit(R5_UPTODATE, &dev->flags);
3360 				s->locked++;
3361 			} else if (test_bit(R5_InJournal, &dev->flags)) {
3362 				set_bit(R5_LOCKED, &dev->flags);
3363 				s->locked++;
3364 			}
3365 		}
3366 		/* if we are not expanding this is a proper write request, and
3367 		 * there will be bios with new data to be drained into the
3368 		 * stripe cache
3369 		 */
3370 		if (!expand) {
3371 			if (!s->locked)
3372 				/* False alarm, nothing to do */
3373 				return;
3374 			sh->reconstruct_state = reconstruct_state_drain_run;
3375 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3376 		} else
3377 			sh->reconstruct_state = reconstruct_state_run;
3378 
3379 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3380 
3381 		if (s->locked + conf->max_degraded == disks)
3382 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
3383 				atomic_inc(&conf->pending_full_writes);
3384 	} else {
3385 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
3386 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
3387 		BUG_ON(level == 6 &&
3388 			(!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
3389 			   test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
3390 
3391 		for (i = disks; i--; ) {
3392 			struct r5dev *dev = &sh->dev[i];
3393 			if (i == pd_idx || i == qd_idx)
3394 				continue;
3395 
3396 			if (dev->towrite &&
3397 			    (test_bit(R5_UPTODATE, &dev->flags) ||
3398 			     test_bit(R5_Wantcompute, &dev->flags))) {
3399 				set_bit(R5_Wantdrain, &dev->flags);
3400 				set_bit(R5_LOCKED, &dev->flags);
3401 				clear_bit(R5_UPTODATE, &dev->flags);
3402 				s->locked++;
3403 			} else if (test_bit(R5_InJournal, &dev->flags)) {
3404 				set_bit(R5_LOCKED, &dev->flags);
3405 				s->locked++;
3406 			}
3407 		}
3408 		if (!s->locked)
3409 			/* False alarm - nothing to do */
3410 			return;
3411 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
3412 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
3413 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3414 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3415 	}
3416 
3417 	/* keep the parity disk(s) locked while asynchronous operations
3418 	 * are in flight
3419 	 */
3420 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
3421 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3422 	s->locked++;
3423 
3424 	if (level == 6) {
3425 		int qd_idx = sh->qd_idx;
3426 		struct r5dev *dev = &sh->dev[qd_idx];
3427 
3428 		set_bit(R5_LOCKED, &dev->flags);
3429 		clear_bit(R5_UPTODATE, &dev->flags);
3430 		s->locked++;
3431 	}
3432 
3433 	if (raid5_has_ppl(sh->raid_conf) && sh->ppl_page &&
3434 	    test_bit(STRIPE_OP_BIODRAIN, &s->ops_request) &&
3435 	    !test_bit(STRIPE_FULL_WRITE, &sh->state) &&
3436 	    test_bit(R5_Insync, &sh->dev[pd_idx].flags))
3437 		set_bit(STRIPE_OP_PARTIAL_PARITY, &s->ops_request);
3438 
3439 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
3440 		__func__, (unsigned long long)sh->sector,
3441 		s->locked, s->ops_request);
3442 }
3443 
3444 static bool stripe_bio_overlaps(struct stripe_head *sh, struct bio *bi,
3445 				int dd_idx, int forwrite)
3446 {
3447 	struct r5conf *conf = sh->raid_conf;
3448 	struct bio **bip;
3449 
3450 	pr_debug("checking bi b#%llu to stripe s#%llu\n",
3451 		 bi->bi_iter.bi_sector, sh->sector);
3452 
3453 	/* Don't allow new IO added to stripes in batch list */
3454 	if (sh->batch_head)
3455 		return true;
3456 
3457 	if (forwrite)
3458 		bip = &sh->dev[dd_idx].towrite;
3459 	else
3460 		bip = &sh->dev[dd_idx].toread;
3461 
3462 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
3463 		if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
3464 			return true;
3465 		bip = &(*bip)->bi_next;
3466 	}
3467 
3468 	if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
3469 		return true;
3470 
3471 	if (forwrite && raid5_has_ppl(conf)) {
3472 		/*
3473 		 * With PPL only writes to consecutive data chunks within a
3474 		 * stripe are allowed because for a single stripe_head we can
3475 		 * only have one PPL entry at a time, which describes one data
3476 		 * range. Not really an overlap, but wait_for_overlap can be
3477 		 * used to handle this.
3478 		 */
3479 		sector_t sector;
3480 		sector_t first = 0;
3481 		sector_t last = 0;
3482 		int count = 0;
3483 		int i;
3484 
3485 		for (i = 0; i < sh->disks; i++) {
3486 			if (i != sh->pd_idx &&
3487 			    (i == dd_idx || sh->dev[i].towrite)) {
3488 				sector = sh->dev[i].sector;
3489 				if (count == 0 || sector < first)
3490 					first = sector;
3491 				if (sector > last)
3492 					last = sector;
3493 				count++;
3494 			}
3495 		}
3496 
3497 		if (first + conf->chunk_sectors * (count - 1) != last)
3498 			return true;
3499 	}
3500 
3501 	return false;
3502 }
3503 
3504 static void __add_stripe_bio(struct stripe_head *sh, struct bio *bi,
3505 			     int dd_idx, int forwrite, int previous)
3506 {
3507 	struct r5conf *conf = sh->raid_conf;
3508 	struct bio **bip;
3509 	int firstwrite = 0;
3510 
3511 	if (forwrite) {
3512 		bip = &sh->dev[dd_idx].towrite;
3513 		if (!*bip)
3514 			firstwrite = 1;
3515 	} else {
3516 		bip = &sh->dev[dd_idx].toread;
3517 	}
3518 
3519 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector)
3520 		bip = &(*bip)->bi_next;
3521 
3522 	if (!forwrite || previous)
3523 		clear_bit(STRIPE_BATCH_READY, &sh->state);
3524 
3525 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3526 	if (*bip)
3527 		bi->bi_next = *bip;
3528 	*bip = bi;
3529 	bio_inc_remaining(bi);
3530 	md_write_inc(conf->mddev, bi);
3531 
3532 	if (forwrite) {
3533 		/* check if page is covered */
3534 		sector_t sector = sh->dev[dd_idx].sector;
3535 		for (bi=sh->dev[dd_idx].towrite;
3536 		     sector < sh->dev[dd_idx].sector + RAID5_STRIPE_SECTORS(conf) &&
3537 			     bi && bi->bi_iter.bi_sector <= sector;
3538 		     bi = r5_next_bio(conf, bi, sh->dev[dd_idx].sector)) {
3539 			if (bio_end_sector(bi) >= sector)
3540 				sector = bio_end_sector(bi);
3541 		}
3542 		if (sector >= sh->dev[dd_idx].sector + RAID5_STRIPE_SECTORS(conf))
3543 			if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3544 				sh->overwrite_disks++;
3545 	}
3546 
3547 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d, logical %llu\n",
3548 		 (*bip)->bi_iter.bi_sector, sh->sector, dd_idx,
3549 		 sh->dev[dd_idx].sector);
3550 
3551 	if (conf->mddev->bitmap && firstwrite) {
3552 		/* Cannot hold spinlock over bitmap_startwrite,
3553 		 * but must ensure this isn't added to a batch until
3554 		 * we have added to the bitmap and set bm_seq.
3555 		 * So set STRIPE_BITMAP_PENDING to prevent
3556 		 * batching.
3557 		 * If multiple __add_stripe_bio() calls race here they
3558 		 * much all set STRIPE_BITMAP_PENDING.  So only the first one
3559 		 * to complete "bitmap_startwrite" gets to set
3560 		 * STRIPE_BIT_DELAY.  This is important as once a stripe
3561 		 * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3562 		 * any more.
3563 		 */
3564 		set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3565 		spin_unlock_irq(&sh->stripe_lock);
3566 		md_bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3567 				     RAID5_STRIPE_SECTORS(conf), 0);
3568 		spin_lock_irq(&sh->stripe_lock);
3569 		clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3570 		if (!sh->batch_head) {
3571 			sh->bm_seq = conf->seq_flush+1;
3572 			set_bit(STRIPE_BIT_DELAY, &sh->state);
3573 		}
3574 	}
3575 }
3576 
3577 /*
3578  * Each stripe/dev can have one or more bios attached.
3579  * toread/towrite point to the first in a chain.
3580  * The bi_next chain must be in order.
3581  */
3582 static bool add_stripe_bio(struct stripe_head *sh, struct bio *bi,
3583 			   int dd_idx, int forwrite, int previous)
3584 {
3585 	spin_lock_irq(&sh->stripe_lock);
3586 
3587 	if (stripe_bio_overlaps(sh, bi, dd_idx, forwrite)) {
3588 		set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3589 		spin_unlock_irq(&sh->stripe_lock);
3590 		return false;
3591 	}
3592 
3593 	__add_stripe_bio(sh, bi, dd_idx, forwrite, previous);
3594 	spin_unlock_irq(&sh->stripe_lock);
3595 	return true;
3596 }
3597 
3598 static void end_reshape(struct r5conf *conf);
3599 
3600 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3601 			    struct stripe_head *sh)
3602 {
3603 	int sectors_per_chunk =
3604 		previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3605 	int dd_idx;
3606 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
3607 	int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3608 
3609 	raid5_compute_sector(conf,
3610 			     stripe * (disks - conf->max_degraded)
3611 			     *sectors_per_chunk + chunk_offset,
3612 			     previous,
3613 			     &dd_idx, sh);
3614 }
3615 
3616 static void
3617 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3618 		     struct stripe_head_state *s, int disks)
3619 {
3620 	int i;
3621 	BUG_ON(sh->batch_head);
3622 	for (i = disks; i--; ) {
3623 		struct bio *bi;
3624 		int bitmap_end = 0;
3625 
3626 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3627 			struct md_rdev *rdev = conf->disks[i].rdev;
3628 
3629 			if (rdev && test_bit(In_sync, &rdev->flags) &&
3630 			    !test_bit(Faulty, &rdev->flags))
3631 				atomic_inc(&rdev->nr_pending);
3632 			else
3633 				rdev = NULL;
3634 			if (rdev) {
3635 				if (!rdev_set_badblocks(
3636 					    rdev,
3637 					    sh->sector,
3638 					    RAID5_STRIPE_SECTORS(conf), 0))
3639 					md_error(conf->mddev, rdev);
3640 				rdev_dec_pending(rdev, conf->mddev);
3641 			}
3642 		}
3643 		spin_lock_irq(&sh->stripe_lock);
3644 		/* fail all writes first */
3645 		bi = sh->dev[i].towrite;
3646 		sh->dev[i].towrite = NULL;
3647 		sh->overwrite_disks = 0;
3648 		spin_unlock_irq(&sh->stripe_lock);
3649 		if (bi)
3650 			bitmap_end = 1;
3651 
3652 		log_stripe_write_finished(sh);
3653 
3654 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3655 			wake_up(&conf->wait_for_overlap);
3656 
3657 		while (bi && bi->bi_iter.bi_sector <
3658 			sh->dev[i].sector + RAID5_STRIPE_SECTORS(conf)) {
3659 			struct bio *nextbi = r5_next_bio(conf, bi, sh->dev[i].sector);
3660 
3661 			md_write_end(conf->mddev);
3662 			bio_io_error(bi);
3663 			bi = nextbi;
3664 		}
3665 		if (bitmap_end)
3666 			md_bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3667 					   RAID5_STRIPE_SECTORS(conf), 0, 0);
3668 		bitmap_end = 0;
3669 		/* and fail all 'written' */
3670 		bi = sh->dev[i].written;
3671 		sh->dev[i].written = NULL;
3672 		if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3673 			WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3674 			sh->dev[i].page = sh->dev[i].orig_page;
3675 		}
3676 
3677 		if (bi) bitmap_end = 1;
3678 		while (bi && bi->bi_iter.bi_sector <
3679 		       sh->dev[i].sector + RAID5_STRIPE_SECTORS(conf)) {
3680 			struct bio *bi2 = r5_next_bio(conf, bi, sh->dev[i].sector);
3681 
3682 			md_write_end(conf->mddev);
3683 			bio_io_error(bi);
3684 			bi = bi2;
3685 		}
3686 
3687 		/* fail any reads if this device is non-operational and
3688 		 * the data has not reached the cache yet.
3689 		 */
3690 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3691 		    s->failed > conf->max_degraded &&
3692 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3693 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
3694 			spin_lock_irq(&sh->stripe_lock);
3695 			bi = sh->dev[i].toread;
3696 			sh->dev[i].toread = NULL;
3697 			spin_unlock_irq(&sh->stripe_lock);
3698 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3699 				wake_up(&conf->wait_for_overlap);
3700 			if (bi)
3701 				s->to_read--;
3702 			while (bi && bi->bi_iter.bi_sector <
3703 			       sh->dev[i].sector + RAID5_STRIPE_SECTORS(conf)) {
3704 				struct bio *nextbi =
3705 					r5_next_bio(conf, bi, sh->dev[i].sector);
3706 
3707 				bio_io_error(bi);
3708 				bi = nextbi;
3709 			}
3710 		}
3711 		if (bitmap_end)
3712 			md_bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3713 					   RAID5_STRIPE_SECTORS(conf), 0, 0);
3714 		/* If we were in the middle of a write the parity block might
3715 		 * still be locked - so just clear all R5_LOCKED flags
3716 		 */
3717 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
3718 	}
3719 	s->to_write = 0;
3720 	s->written = 0;
3721 
3722 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3723 		if (atomic_dec_and_test(&conf->pending_full_writes))
3724 			md_wakeup_thread(conf->mddev->thread);
3725 }
3726 
3727 static void
3728 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3729 		   struct stripe_head_state *s)
3730 {
3731 	int abort = 0;
3732 	int i;
3733 
3734 	BUG_ON(sh->batch_head);
3735 	clear_bit(STRIPE_SYNCING, &sh->state);
3736 	if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3737 		wake_up(&conf->wait_for_overlap);
3738 	s->syncing = 0;
3739 	s->replacing = 0;
3740 	/* There is nothing more to do for sync/check/repair.
3741 	 * Don't even need to abort as that is handled elsewhere
3742 	 * if needed, and not always wanted e.g. if there is a known
3743 	 * bad block here.
3744 	 * For recover/replace we need to record a bad block on all
3745 	 * non-sync devices, or abort the recovery
3746 	 */
3747 	if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3748 		/* During recovery devices cannot be removed, so
3749 		 * locking and refcounting of rdevs is not needed
3750 		 */
3751 		for (i = 0; i < conf->raid_disks; i++) {
3752 			struct md_rdev *rdev = conf->disks[i].rdev;
3753 
3754 			if (rdev
3755 			    && !test_bit(Faulty, &rdev->flags)
3756 			    && !test_bit(In_sync, &rdev->flags)
3757 			    && !rdev_set_badblocks(rdev, sh->sector,
3758 						   RAID5_STRIPE_SECTORS(conf), 0))
3759 				abort = 1;
3760 			rdev = conf->disks[i].replacement;
3761 
3762 			if (rdev
3763 			    && !test_bit(Faulty, &rdev->flags)
3764 			    && !test_bit(In_sync, &rdev->flags)
3765 			    && !rdev_set_badblocks(rdev, sh->sector,
3766 						   RAID5_STRIPE_SECTORS(conf), 0))
3767 				abort = 1;
3768 		}
3769 		if (abort)
3770 			conf->recovery_disabled =
3771 				conf->mddev->recovery_disabled;
3772 	}
3773 	md_done_sync(conf->mddev, RAID5_STRIPE_SECTORS(conf), !abort);
3774 }
3775 
3776 static int want_replace(struct stripe_head *sh, int disk_idx)
3777 {
3778 	struct md_rdev *rdev;
3779 	int rv = 0;
3780 
3781 	rdev = sh->raid_conf->disks[disk_idx].replacement;
3782 	if (rdev
3783 	    && !test_bit(Faulty, &rdev->flags)
3784 	    && !test_bit(In_sync, &rdev->flags)
3785 	    && (rdev->recovery_offset <= sh->sector
3786 		|| rdev->mddev->recovery_cp <= sh->sector))
3787 		rv = 1;
3788 	return rv;
3789 }
3790 
3791 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3792 			   int disk_idx, int disks)
3793 {
3794 	struct r5dev *dev = &sh->dev[disk_idx];
3795 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3796 				  &sh->dev[s->failed_num[1]] };
3797 	int i;
3798 	bool force_rcw = (sh->raid_conf->rmw_level == PARITY_DISABLE_RMW);
3799 
3800 
3801 	if (test_bit(R5_LOCKED, &dev->flags) ||
3802 	    test_bit(R5_UPTODATE, &dev->flags))
3803 		/* No point reading this as we already have it or have
3804 		 * decided to get it.
3805 		 */
3806 		return 0;
3807 
3808 	if (dev->toread ||
3809 	    (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3810 		/* We need this block to directly satisfy a request */
3811 		return 1;
3812 
3813 	if (s->syncing || s->expanding ||
3814 	    (s->replacing && want_replace(sh, disk_idx)))
3815 		/* When syncing, or expanding we read everything.
3816 		 * When replacing, we need the replaced block.
3817 		 */
3818 		return 1;
3819 
3820 	if ((s->failed >= 1 && fdev[0]->toread) ||
3821 	    (s->failed >= 2 && fdev[1]->toread))
3822 		/* If we want to read from a failed device, then
3823 		 * we need to actually read every other device.
3824 		 */
3825 		return 1;
3826 
3827 	/* Sometimes neither read-modify-write nor reconstruct-write
3828 	 * cycles can work.  In those cases we read every block we
3829 	 * can.  Then the parity-update is certain to have enough to
3830 	 * work with.
3831 	 * This can only be a problem when we need to write something,
3832 	 * and some device has failed.  If either of those tests
3833 	 * fail we need look no further.
3834 	 */
3835 	if (!s->failed || !s->to_write)
3836 		return 0;
3837 
3838 	if (test_bit(R5_Insync, &dev->flags) &&
3839 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3840 		/* Pre-reads at not permitted until after short delay
3841 		 * to gather multiple requests.  However if this
3842 		 * device is no Insync, the block could only be computed
3843 		 * and there is no need to delay that.
3844 		 */
3845 		return 0;
3846 
3847 	for (i = 0; i < s->failed && i < 2; i++) {
3848 		if (fdev[i]->towrite &&
3849 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3850 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3851 			/* If we have a partial write to a failed
3852 			 * device, then we will need to reconstruct
3853 			 * the content of that device, so all other
3854 			 * devices must be read.
3855 			 */
3856 			return 1;
3857 
3858 		if (s->failed >= 2 &&
3859 		    (fdev[i]->towrite ||
3860 		     s->failed_num[i] == sh->pd_idx ||
3861 		     s->failed_num[i] == sh->qd_idx) &&
3862 		    !test_bit(R5_UPTODATE, &fdev[i]->flags))
3863 			/* In max degraded raid6, If the failed disk is P, Q,
3864 			 * or we want to read the failed disk, we need to do
3865 			 * reconstruct-write.
3866 			 */
3867 			force_rcw = true;
3868 	}
3869 
3870 	/* If we are forced to do a reconstruct-write, because parity
3871 	 * cannot be trusted and we are currently recovering it, there
3872 	 * is extra need to be careful.
3873 	 * If one of the devices that we would need to read, because
3874 	 * it is not being overwritten (and maybe not written at all)
3875 	 * is missing/faulty, then we need to read everything we can.
3876 	 */
3877 	if (!force_rcw &&
3878 	    sh->sector < sh->raid_conf->mddev->recovery_cp)
3879 		/* reconstruct-write isn't being forced */
3880 		return 0;
3881 	for (i = 0; i < s->failed && i < 2; i++) {
3882 		if (s->failed_num[i] != sh->pd_idx &&
3883 		    s->failed_num[i] != sh->qd_idx &&
3884 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3885 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3886 			return 1;
3887 	}
3888 
3889 	return 0;
3890 }
3891 
3892 /* fetch_block - checks the given member device to see if its data needs
3893  * to be read or computed to satisfy a request.
3894  *
3895  * Returns 1 when no more member devices need to be checked, otherwise returns
3896  * 0 to tell the loop in handle_stripe_fill to continue
3897  */
3898 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3899 		       int disk_idx, int disks)
3900 {
3901 	struct r5dev *dev = &sh->dev[disk_idx];
3902 
3903 	/* is the data in this block needed, and can we get it? */
3904 	if (need_this_block(sh, s, disk_idx, disks)) {
3905 		/* we would like to get this block, possibly by computing it,
3906 		 * otherwise read it if the backing disk is insync
3907 		 */
3908 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3909 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
3910 		BUG_ON(sh->batch_head);
3911 
3912 		/*
3913 		 * In the raid6 case if the only non-uptodate disk is P
3914 		 * then we already trusted P to compute the other failed
3915 		 * drives. It is safe to compute rather than re-read P.
3916 		 * In other cases we only compute blocks from failed
3917 		 * devices, otherwise check/repair might fail to detect
3918 		 * a real inconsistency.
3919 		 */
3920 
3921 		if ((s->uptodate == disks - 1) &&
3922 		    ((sh->qd_idx >= 0 && sh->pd_idx == disk_idx) ||
3923 		    (s->failed && (disk_idx == s->failed_num[0] ||
3924 				   disk_idx == s->failed_num[1])))) {
3925 			/* have disk failed, and we're requested to fetch it;
3926 			 * do compute it
3927 			 */
3928 			pr_debug("Computing stripe %llu block %d\n",
3929 			       (unsigned long long)sh->sector, disk_idx);
3930 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3931 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3932 			set_bit(R5_Wantcompute, &dev->flags);
3933 			sh->ops.target = disk_idx;
3934 			sh->ops.target2 = -1; /* no 2nd target */
3935 			s->req_compute = 1;
3936 			/* Careful: from this point on 'uptodate' is in the eye
3937 			 * of raid_run_ops which services 'compute' operations
3938 			 * before writes. R5_Wantcompute flags a block that will
3939 			 * be R5_UPTODATE by the time it is needed for a
3940 			 * subsequent operation.
3941 			 */
3942 			s->uptodate++;
3943 			return 1;
3944 		} else if (s->uptodate == disks-2 && s->failed >= 2) {
3945 			/* Computing 2-failure is *very* expensive; only
3946 			 * do it if failed >= 2
3947 			 */
3948 			int other;
3949 			for (other = disks; other--; ) {
3950 				if (other == disk_idx)
3951 					continue;
3952 				if (!test_bit(R5_UPTODATE,
3953 				      &sh->dev[other].flags))
3954 					break;
3955 			}
3956 			BUG_ON(other < 0);
3957 			pr_debug("Computing stripe %llu blocks %d,%d\n",
3958 			       (unsigned long long)sh->sector,
3959 			       disk_idx, other);
3960 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3961 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3962 			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3963 			set_bit(R5_Wantcompute, &sh->dev[other].flags);
3964 			sh->ops.target = disk_idx;
3965 			sh->ops.target2 = other;
3966 			s->uptodate += 2;
3967 			s->req_compute = 1;
3968 			return 1;
3969 		} else if (test_bit(R5_Insync, &dev->flags)) {
3970 			set_bit(R5_LOCKED, &dev->flags);
3971 			set_bit(R5_Wantread, &dev->flags);
3972 			s->locked++;
3973 			pr_debug("Reading block %d (sync=%d)\n",
3974 				disk_idx, s->syncing);
3975 		}
3976 	}
3977 
3978 	return 0;
3979 }
3980 
3981 /*
3982  * handle_stripe_fill - read or compute data to satisfy pending requests.
3983  */
3984 static void handle_stripe_fill(struct stripe_head *sh,
3985 			       struct stripe_head_state *s,
3986 			       int disks)
3987 {
3988 	int i;
3989 
3990 	/* look for blocks to read/compute, skip this if a compute
3991 	 * is already in flight, or if the stripe contents are in the
3992 	 * midst of changing due to a write
3993 	 */
3994 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3995 	    !sh->reconstruct_state) {
3996 
3997 		/*
3998 		 * For degraded stripe with data in journal, do not handle
3999 		 * read requests yet, instead, flush the stripe to raid
4000 		 * disks first, this avoids handling complex rmw of write
4001 		 * back cache (prexor with orig_page, and then xor with
4002 		 * page) in the read path
4003 		 */
4004 		if (s->to_read && s->injournal && s->failed) {
4005 			if (test_bit(STRIPE_R5C_CACHING, &sh->state))
4006 				r5c_make_stripe_write_out(sh);
4007 			goto out;
4008 		}
4009 
4010 		for (i = disks; i--; )
4011 			if (fetch_block(sh, s, i, disks))
4012 				break;
4013 	}
4014 out:
4015 	set_bit(STRIPE_HANDLE, &sh->state);
4016 }
4017 
4018 static void break_stripe_batch_list(struct stripe_head *head_sh,
4019 				    unsigned long handle_flags);
4020 /* handle_stripe_clean_event
4021  * any written block on an uptodate or failed drive can be returned.
4022  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
4023  * never LOCKED, so we don't need to test 'failed' directly.
4024  */
4025 static void handle_stripe_clean_event(struct r5conf *conf,
4026 	struct stripe_head *sh, int disks)
4027 {
4028 	int i;
4029 	struct r5dev *dev;
4030 	int discard_pending = 0;
4031 	struct stripe_head *head_sh = sh;
4032 	bool do_endio = false;
4033 
4034 	for (i = disks; i--; )
4035 		if (sh->dev[i].written) {
4036 			dev = &sh->dev[i];
4037 			if (!test_bit(R5_LOCKED, &dev->flags) &&
4038 			    (test_bit(R5_UPTODATE, &dev->flags) ||
4039 			     test_bit(R5_Discard, &dev->flags) ||
4040 			     test_bit(R5_SkipCopy, &dev->flags))) {
4041 				/* We can return any write requests */
4042 				struct bio *wbi, *wbi2;
4043 				pr_debug("Return write for disc %d\n", i);
4044 				if (test_and_clear_bit(R5_Discard, &dev->flags))
4045 					clear_bit(R5_UPTODATE, &dev->flags);
4046 				if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
4047 					WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
4048 				}
4049 				do_endio = true;
4050 
4051 returnbi:
4052 				dev->page = dev->orig_page;
4053 				wbi = dev->written;
4054 				dev->written = NULL;
4055 				while (wbi && wbi->bi_iter.bi_sector <
4056 					dev->sector + RAID5_STRIPE_SECTORS(conf)) {
4057 					wbi2 = r5_next_bio(conf, wbi, dev->sector);
4058 					md_write_end(conf->mddev);
4059 					bio_endio(wbi);
4060 					wbi = wbi2;
4061 				}
4062 				md_bitmap_endwrite(conf->mddev->bitmap, sh->sector,
4063 						   RAID5_STRIPE_SECTORS(conf),
4064 						   !test_bit(STRIPE_DEGRADED, &sh->state),
4065 						   0);
4066 				if (head_sh->batch_head) {
4067 					sh = list_first_entry(&sh->batch_list,
4068 							      struct stripe_head,
4069 							      batch_list);
4070 					if (sh != head_sh) {
4071 						dev = &sh->dev[i];
4072 						goto returnbi;
4073 					}
4074 				}
4075 				sh = head_sh;
4076 				dev = &sh->dev[i];
4077 			} else if (test_bit(R5_Discard, &dev->flags))
4078 				discard_pending = 1;
4079 		}
4080 
4081 	log_stripe_write_finished(sh);
4082 
4083 	if (!discard_pending &&
4084 	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
4085 		int hash;
4086 		clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
4087 		clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
4088 		if (sh->qd_idx >= 0) {
4089 			clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
4090 			clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
4091 		}
4092 		/* now that discard is done we can proceed with any sync */
4093 		clear_bit(STRIPE_DISCARD, &sh->state);
4094 		/*
4095 		 * SCSI discard will change some bio fields and the stripe has
4096 		 * no updated data, so remove it from hash list and the stripe
4097 		 * will be reinitialized
4098 		 */
4099 unhash:
4100 		hash = sh->hash_lock_index;
4101 		spin_lock_irq(conf->hash_locks + hash);
4102 		remove_hash(sh);
4103 		spin_unlock_irq(conf->hash_locks + hash);
4104 		if (head_sh->batch_head) {
4105 			sh = list_first_entry(&sh->batch_list,
4106 					      struct stripe_head, batch_list);
4107 			if (sh != head_sh)
4108 					goto unhash;
4109 		}
4110 		sh = head_sh;
4111 
4112 		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
4113 			set_bit(STRIPE_HANDLE, &sh->state);
4114 
4115 	}
4116 
4117 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
4118 		if (atomic_dec_and_test(&conf->pending_full_writes))
4119 			md_wakeup_thread(conf->mddev->thread);
4120 
4121 	if (head_sh->batch_head && do_endio)
4122 		break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
4123 }
4124 
4125 /*
4126  * For RMW in write back cache, we need extra page in prexor to store the
4127  * old data. This page is stored in dev->orig_page.
4128  *
4129  * This function checks whether we have data for prexor. The exact logic
4130  * is:
4131  *       R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
4132  */
4133 static inline bool uptodate_for_rmw(struct r5dev *dev)
4134 {
4135 	return (test_bit(R5_UPTODATE, &dev->flags)) &&
4136 		(!test_bit(R5_InJournal, &dev->flags) ||
4137 		 test_bit(R5_OrigPageUPTDODATE, &dev->flags));
4138 }
4139 
4140 static int handle_stripe_dirtying(struct r5conf *conf,
4141 				  struct stripe_head *sh,
4142 				  struct stripe_head_state *s,
4143 				  int disks)
4144 {
4145 	int rmw = 0, rcw = 0, i;
4146 	sector_t recovery_cp = conf->mddev->recovery_cp;
4147 
4148 	/* Check whether resync is now happening or should start.
4149 	 * If yes, then the array is dirty (after unclean shutdown or
4150 	 * initial creation), so parity in some stripes might be inconsistent.
4151 	 * In this case, we need to always do reconstruct-write, to ensure
4152 	 * that in case of drive failure or read-error correction, we
4153 	 * generate correct data from the parity.
4154 	 */
4155 	if (conf->rmw_level == PARITY_DISABLE_RMW ||
4156 	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
4157 	     s->failed == 0)) {
4158 		/* Calculate the real rcw later - for now make it
4159 		 * look like rcw is cheaper
4160 		 */
4161 		rcw = 1; rmw = 2;
4162 		pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
4163 			 conf->rmw_level, (unsigned long long)recovery_cp,
4164 			 (unsigned long long)sh->sector);
4165 	} else for (i = disks; i--; ) {
4166 		/* would I have to read this buffer for read_modify_write */
4167 		struct r5dev *dev = &sh->dev[i];
4168 		if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
4169 		     i == sh->pd_idx || i == sh->qd_idx ||
4170 		     test_bit(R5_InJournal, &dev->flags)) &&
4171 		    !test_bit(R5_LOCKED, &dev->flags) &&
4172 		    !(uptodate_for_rmw(dev) ||
4173 		      test_bit(R5_Wantcompute, &dev->flags))) {
4174 			if (test_bit(R5_Insync, &dev->flags))
4175 				rmw++;
4176 			else
4177 				rmw += 2*disks;  /* cannot read it */
4178 		}
4179 		/* Would I have to read this buffer for reconstruct_write */
4180 		if (!test_bit(R5_OVERWRITE, &dev->flags) &&
4181 		    i != sh->pd_idx && i != sh->qd_idx &&
4182 		    !test_bit(R5_LOCKED, &dev->flags) &&
4183 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
4184 		      test_bit(R5_Wantcompute, &dev->flags))) {
4185 			if (test_bit(R5_Insync, &dev->flags))
4186 				rcw++;
4187 			else
4188 				rcw += 2*disks;
4189 		}
4190 	}
4191 
4192 	pr_debug("for sector %llu state 0x%lx, rmw=%d rcw=%d\n",
4193 		 (unsigned long long)sh->sector, sh->state, rmw, rcw);
4194 	set_bit(STRIPE_HANDLE, &sh->state);
4195 	if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
4196 		/* prefer read-modify-write, but need to get some data */
4197 		mddev_add_trace_msg(conf->mddev, "raid5 rmw %llu %d",
4198 				sh->sector, rmw);
4199 
4200 		for (i = disks; i--; ) {
4201 			struct r5dev *dev = &sh->dev[i];
4202 			if (test_bit(R5_InJournal, &dev->flags) &&
4203 			    dev->page == dev->orig_page &&
4204 			    !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {
4205 				/* alloc page for prexor */
4206 				struct page *p = alloc_page(GFP_NOIO);
4207 
4208 				if (p) {
4209 					dev->orig_page = p;
4210 					continue;
4211 				}
4212 
4213 				/*
4214 				 * alloc_page() failed, try use
4215 				 * disk_info->extra_page
4216 				 */
4217 				if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,
4218 						      &conf->cache_state)) {
4219 					r5c_use_extra_page(sh);
4220 					break;
4221 				}
4222 
4223 				/* extra_page in use, add to delayed_list */
4224 				set_bit(STRIPE_DELAYED, &sh->state);
4225 				s->waiting_extra_page = 1;
4226 				return -EAGAIN;
4227 			}
4228 		}
4229 
4230 		for (i = disks; i--; ) {
4231 			struct r5dev *dev = &sh->dev[i];
4232 			if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
4233 			     i == sh->pd_idx || i == sh->qd_idx ||
4234 			     test_bit(R5_InJournal, &dev->flags)) &&
4235 			    !test_bit(R5_LOCKED, &dev->flags) &&
4236 			    !(uptodate_for_rmw(dev) ||
4237 			      test_bit(R5_Wantcompute, &dev->flags)) &&
4238 			    test_bit(R5_Insync, &dev->flags)) {
4239 				if (test_bit(STRIPE_PREREAD_ACTIVE,
4240 					     &sh->state)) {
4241 					pr_debug("Read_old block %d for r-m-w\n",
4242 						 i);
4243 					set_bit(R5_LOCKED, &dev->flags);
4244 					set_bit(R5_Wantread, &dev->flags);
4245 					s->locked++;
4246 				} else
4247 					set_bit(STRIPE_DELAYED, &sh->state);
4248 			}
4249 		}
4250 	}
4251 	if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
4252 		/* want reconstruct write, but need to get some data */
4253 		int qread =0;
4254 		rcw = 0;
4255 		for (i = disks; i--; ) {
4256 			struct r5dev *dev = &sh->dev[i];
4257 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
4258 			    i != sh->pd_idx && i != sh->qd_idx &&
4259 			    !test_bit(R5_LOCKED, &dev->flags) &&
4260 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
4261 			      test_bit(R5_Wantcompute, &dev->flags))) {
4262 				rcw++;
4263 				if (test_bit(R5_Insync, &dev->flags) &&
4264 				    test_bit(STRIPE_PREREAD_ACTIVE,
4265 					     &sh->state)) {
4266 					pr_debug("Read_old block "
4267 						"%d for Reconstruct\n", i);
4268 					set_bit(R5_LOCKED, &dev->flags);
4269 					set_bit(R5_Wantread, &dev->flags);
4270 					s->locked++;
4271 					qread++;
4272 				} else
4273 					set_bit(STRIPE_DELAYED, &sh->state);
4274 			}
4275 		}
4276 		if (rcw && !mddev_is_dm(conf->mddev))
4277 			blk_add_trace_msg(conf->mddev->gendisk->queue,
4278 				"raid5 rcw %llu %d %d %d",
4279 				(unsigned long long)sh->sector, rcw, qread,
4280 				test_bit(STRIPE_DELAYED, &sh->state));
4281 	}
4282 
4283 	if (rcw > disks && rmw > disks &&
4284 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4285 		set_bit(STRIPE_DELAYED, &sh->state);
4286 
4287 	/* now if nothing is locked, and if we have enough data,
4288 	 * we can start a write request
4289 	 */
4290 	/* since handle_stripe can be called at any time we need to handle the
4291 	 * case where a compute block operation has been submitted and then a
4292 	 * subsequent call wants to start a write request.  raid_run_ops only
4293 	 * handles the case where compute block and reconstruct are requested
4294 	 * simultaneously.  If this is not the case then new writes need to be
4295 	 * held off until the compute completes.
4296 	 */
4297 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
4298 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
4299 	     !test_bit(STRIPE_BIT_DELAY, &sh->state)))
4300 		schedule_reconstruction(sh, s, rcw == 0, 0);
4301 	return 0;
4302 }
4303 
4304 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
4305 				struct stripe_head_state *s, int disks)
4306 {
4307 	struct r5dev *dev = NULL;
4308 
4309 	BUG_ON(sh->batch_head);
4310 	set_bit(STRIPE_HANDLE, &sh->state);
4311 
4312 	switch (sh->check_state) {
4313 	case check_state_idle:
4314 		/* start a new check operation if there are no failures */
4315 		if (s->failed == 0) {
4316 			BUG_ON(s->uptodate != disks);
4317 			sh->check_state = check_state_run;
4318 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
4319 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
4320 			s->uptodate--;
4321 			break;
4322 		}
4323 		dev = &sh->dev[s->failed_num[0]];
4324 		fallthrough;
4325 	case check_state_compute_result:
4326 		sh->check_state = check_state_idle;
4327 		if (!dev)
4328 			dev = &sh->dev[sh->pd_idx];
4329 
4330 		/* check that a write has not made the stripe insync */
4331 		if (test_bit(STRIPE_INSYNC, &sh->state))
4332 			break;
4333 
4334 		/* either failed parity check, or recovery is happening */
4335 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
4336 		BUG_ON(s->uptodate != disks);
4337 
4338 		set_bit(R5_LOCKED, &dev->flags);
4339 		s->locked++;
4340 		set_bit(R5_Wantwrite, &dev->flags);
4341 
4342 		clear_bit(STRIPE_DEGRADED, &sh->state);
4343 		set_bit(STRIPE_INSYNC, &sh->state);
4344 		break;
4345 	case check_state_run:
4346 		break; /* we will be called again upon completion */
4347 	case check_state_check_result:
4348 		sh->check_state = check_state_idle;
4349 
4350 		/* if a failure occurred during the check operation, leave
4351 		 * STRIPE_INSYNC not set and let the stripe be handled again
4352 		 */
4353 		if (s->failed)
4354 			break;
4355 
4356 		/* handle a successful check operation, if parity is correct
4357 		 * we are done.  Otherwise update the mismatch count and repair
4358 		 * parity if !MD_RECOVERY_CHECK
4359 		 */
4360 		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
4361 			/* parity is correct (on disc,
4362 			 * not in buffer any more)
4363 			 */
4364 			set_bit(STRIPE_INSYNC, &sh->state);
4365 		else {
4366 			atomic64_add(RAID5_STRIPE_SECTORS(conf), &conf->mddev->resync_mismatches);
4367 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery)) {
4368 				/* don't try to repair!! */
4369 				set_bit(STRIPE_INSYNC, &sh->state);
4370 				pr_warn_ratelimited("%s: mismatch sector in range "
4371 						    "%llu-%llu\n", mdname(conf->mddev),
4372 						    (unsigned long long) sh->sector,
4373 						    (unsigned long long) sh->sector +
4374 						    RAID5_STRIPE_SECTORS(conf));
4375 			} else {
4376 				sh->check_state = check_state_compute_run;
4377 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4378 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4379 				set_bit(R5_Wantcompute,
4380 					&sh->dev[sh->pd_idx].flags);
4381 				sh->ops.target = sh->pd_idx;
4382 				sh->ops.target2 = -1;
4383 				s->uptodate++;
4384 			}
4385 		}
4386 		break;
4387 	case check_state_compute_run:
4388 		break;
4389 	default:
4390 		pr_err("%s: unknown check_state: %d sector: %llu\n",
4391 		       __func__, sh->check_state,
4392 		       (unsigned long long) sh->sector);
4393 		BUG();
4394 	}
4395 }
4396 
4397 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
4398 				  struct stripe_head_state *s,
4399 				  int disks)
4400 {
4401 	int pd_idx = sh->pd_idx;
4402 	int qd_idx = sh->qd_idx;
4403 	struct r5dev *dev;
4404 
4405 	BUG_ON(sh->batch_head);
4406 	set_bit(STRIPE_HANDLE, &sh->state);
4407 
4408 	BUG_ON(s->failed > 2);
4409 
4410 	/* Want to check and possibly repair P and Q.
4411 	 * However there could be one 'failed' device, in which
4412 	 * case we can only check one of them, possibly using the
4413 	 * other to generate missing data
4414 	 */
4415 
4416 	switch (sh->check_state) {
4417 	case check_state_idle:
4418 		/* start a new check operation if there are < 2 failures */
4419 		if (s->failed == s->q_failed) {
4420 			/* The only possible failed device holds Q, so it
4421 			 * makes sense to check P (If anything else were failed,
4422 			 * we would have used P to recreate it).
4423 			 */
4424 			sh->check_state = check_state_run;
4425 		}
4426 		if (!s->q_failed && s->failed < 2) {
4427 			/* Q is not failed, and we didn't use it to generate
4428 			 * anything, so it makes sense to check it
4429 			 */
4430 			if (sh->check_state == check_state_run)
4431 				sh->check_state = check_state_run_pq;
4432 			else
4433 				sh->check_state = check_state_run_q;
4434 		}
4435 
4436 		/* discard potentially stale zero_sum_result */
4437 		sh->ops.zero_sum_result = 0;
4438 
4439 		if (sh->check_state == check_state_run) {
4440 			/* async_xor_zero_sum destroys the contents of P */
4441 			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
4442 			s->uptodate--;
4443 		}
4444 		if (sh->check_state >= check_state_run &&
4445 		    sh->check_state <= check_state_run_pq) {
4446 			/* async_syndrome_zero_sum preserves P and Q, so
4447 			 * no need to mark them !uptodate here
4448 			 */
4449 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
4450 			break;
4451 		}
4452 
4453 		/* we have 2-disk failure */
4454 		BUG_ON(s->failed != 2);
4455 		fallthrough;
4456 	case check_state_compute_result:
4457 		sh->check_state = check_state_idle;
4458 
4459 		/* check that a write has not made the stripe insync */
4460 		if (test_bit(STRIPE_INSYNC, &sh->state))
4461 			break;
4462 
4463 		/* now write out any block on a failed drive,
4464 		 * or P or Q if they were recomputed
4465 		 */
4466 		dev = NULL;
4467 		if (s->failed == 2) {
4468 			dev = &sh->dev[s->failed_num[1]];
4469 			s->locked++;
4470 			set_bit(R5_LOCKED, &dev->flags);
4471 			set_bit(R5_Wantwrite, &dev->flags);
4472 		}
4473 		if (s->failed >= 1) {
4474 			dev = &sh->dev[s->failed_num[0]];
4475 			s->locked++;
4476 			set_bit(R5_LOCKED, &dev->flags);
4477 			set_bit(R5_Wantwrite, &dev->flags);
4478 		}
4479 		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4480 			dev = &sh->dev[pd_idx];
4481 			s->locked++;
4482 			set_bit(R5_LOCKED, &dev->flags);
4483 			set_bit(R5_Wantwrite, &dev->flags);
4484 		}
4485 		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4486 			dev = &sh->dev[qd_idx];
4487 			s->locked++;
4488 			set_bit(R5_LOCKED, &dev->flags);
4489 			set_bit(R5_Wantwrite, &dev->flags);
4490 		}
4491 		if (WARN_ONCE(dev && !test_bit(R5_UPTODATE, &dev->flags),
4492 			      "%s: disk%td not up to date\n",
4493 			      mdname(conf->mddev),
4494 			      dev - (struct r5dev *) &sh->dev)) {
4495 			clear_bit(R5_LOCKED, &dev->flags);
4496 			clear_bit(R5_Wantwrite, &dev->flags);
4497 			s->locked--;
4498 		}
4499 		clear_bit(STRIPE_DEGRADED, &sh->state);
4500 
4501 		set_bit(STRIPE_INSYNC, &sh->state);
4502 		break;
4503 	case check_state_run:
4504 	case check_state_run_q:
4505 	case check_state_run_pq:
4506 		break; /* we will be called again upon completion */
4507 	case check_state_check_result:
4508 		sh->check_state = check_state_idle;
4509 
4510 		/* handle a successful check operation, if parity is correct
4511 		 * we are done.  Otherwise update the mismatch count and repair
4512 		 * parity if !MD_RECOVERY_CHECK
4513 		 */
4514 		if (sh->ops.zero_sum_result == 0) {
4515 			/* both parities are correct */
4516 			if (!s->failed)
4517 				set_bit(STRIPE_INSYNC, &sh->state);
4518 			else {
4519 				/* in contrast to the raid5 case we can validate
4520 				 * parity, but still have a failure to write
4521 				 * back
4522 				 */
4523 				sh->check_state = check_state_compute_result;
4524 				/* Returning at this point means that we may go
4525 				 * off and bring p and/or q uptodate again so
4526 				 * we make sure to check zero_sum_result again
4527 				 * to verify if p or q need writeback
4528 				 */
4529 			}
4530 		} else {
4531 			atomic64_add(RAID5_STRIPE_SECTORS(conf), &conf->mddev->resync_mismatches);
4532 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery)) {
4533 				/* don't try to repair!! */
4534 				set_bit(STRIPE_INSYNC, &sh->state);
4535 				pr_warn_ratelimited("%s: mismatch sector in range "
4536 						    "%llu-%llu\n", mdname(conf->mddev),
4537 						    (unsigned long long) sh->sector,
4538 						    (unsigned long long) sh->sector +
4539 						    RAID5_STRIPE_SECTORS(conf));
4540 			} else {
4541 				int *target = &sh->ops.target;
4542 
4543 				sh->ops.target = -1;
4544 				sh->ops.target2 = -1;
4545 				sh->check_state = check_state_compute_run;
4546 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4547 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4548 				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4549 					set_bit(R5_Wantcompute,
4550 						&sh->dev[pd_idx].flags);
4551 					*target = pd_idx;
4552 					target = &sh->ops.target2;
4553 					s->uptodate++;
4554 				}
4555 				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4556 					set_bit(R5_Wantcompute,
4557 						&sh->dev[qd_idx].flags);
4558 					*target = qd_idx;
4559 					s->uptodate++;
4560 				}
4561 			}
4562 		}
4563 		break;
4564 	case check_state_compute_run:
4565 		break;
4566 	default:
4567 		pr_warn("%s: unknown check_state: %d sector: %llu\n",
4568 			__func__, sh->check_state,
4569 			(unsigned long long) sh->sector);
4570 		BUG();
4571 	}
4572 }
4573 
4574 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
4575 {
4576 	int i;
4577 
4578 	/* We have read all the blocks in this stripe and now we need to
4579 	 * copy some of them into a target stripe for expand.
4580 	 */
4581 	struct dma_async_tx_descriptor *tx = NULL;
4582 	BUG_ON(sh->batch_head);
4583 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4584 	for (i = 0; i < sh->disks; i++)
4585 		if (i != sh->pd_idx && i != sh->qd_idx) {
4586 			int dd_idx, j;
4587 			struct stripe_head *sh2;
4588 			struct async_submit_ctl submit;
4589 
4590 			sector_t bn = raid5_compute_blocknr(sh, i, 1);
4591 			sector_t s = raid5_compute_sector(conf, bn, 0,
4592 							  &dd_idx, NULL);
4593 			sh2 = raid5_get_active_stripe(conf, NULL, s,
4594 				R5_GAS_NOBLOCK | R5_GAS_NOQUIESCE);
4595 			if (sh2 == NULL)
4596 				/* so far only the early blocks of this stripe
4597 				 * have been requested.  When later blocks
4598 				 * get requested, we will try again
4599 				 */
4600 				continue;
4601 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
4602 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
4603 				/* must have already done this block */
4604 				raid5_release_stripe(sh2);
4605 				continue;
4606 			}
4607 
4608 			/* place all the copies on one channel */
4609 			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4610 			tx = async_memcpy(sh2->dev[dd_idx].page,
4611 					  sh->dev[i].page, sh2->dev[dd_idx].offset,
4612 					  sh->dev[i].offset, RAID5_STRIPE_SIZE(conf),
4613 					  &submit);
4614 
4615 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4616 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4617 			for (j = 0; j < conf->raid_disks; j++)
4618 				if (j != sh2->pd_idx &&
4619 				    j != sh2->qd_idx &&
4620 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
4621 					break;
4622 			if (j == conf->raid_disks) {
4623 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
4624 				set_bit(STRIPE_HANDLE, &sh2->state);
4625 			}
4626 			raid5_release_stripe(sh2);
4627 
4628 		}
4629 	/* done submitting copies, wait for them to complete */
4630 	async_tx_quiesce(&tx);
4631 }
4632 
4633 /*
4634  * handle_stripe - do things to a stripe.
4635  *
4636  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4637  * state of various bits to see what needs to be done.
4638  * Possible results:
4639  *    return some read requests which now have data
4640  *    return some write requests which are safely on storage
4641  *    schedule a read on some buffers
4642  *    schedule a write of some buffers
4643  *    return confirmation of parity correctness
4644  *
4645  */
4646 
4647 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4648 {
4649 	struct r5conf *conf = sh->raid_conf;
4650 	int disks = sh->disks;
4651 	struct r5dev *dev;
4652 	int i;
4653 	int do_recovery = 0;
4654 
4655 	memset(s, 0, sizeof(*s));
4656 
4657 	s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4658 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4659 	s->failed_num[0] = -1;
4660 	s->failed_num[1] = -1;
4661 	s->log_failed = r5l_log_disk_error(conf);
4662 
4663 	/* Now to look around and see what can be done */
4664 	for (i=disks; i--; ) {
4665 		struct md_rdev *rdev;
4666 		int is_bad = 0;
4667 
4668 		dev = &sh->dev[i];
4669 
4670 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4671 			 i, dev->flags,
4672 			 dev->toread, dev->towrite, dev->written);
4673 		/* maybe we can reply to a read
4674 		 *
4675 		 * new wantfill requests are only permitted while
4676 		 * ops_complete_biofill is guaranteed to be inactive
4677 		 */
4678 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4679 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4680 			set_bit(R5_Wantfill, &dev->flags);
4681 
4682 		/* now count some things */
4683 		if (test_bit(R5_LOCKED, &dev->flags))
4684 			s->locked++;
4685 		if (test_bit(R5_UPTODATE, &dev->flags))
4686 			s->uptodate++;
4687 		if (test_bit(R5_Wantcompute, &dev->flags)) {
4688 			s->compute++;
4689 			BUG_ON(s->compute > 2);
4690 		}
4691 
4692 		if (test_bit(R5_Wantfill, &dev->flags))
4693 			s->to_fill++;
4694 		else if (dev->toread)
4695 			s->to_read++;
4696 		if (dev->towrite) {
4697 			s->to_write++;
4698 			if (!test_bit(R5_OVERWRITE, &dev->flags))
4699 				s->non_overwrite++;
4700 		}
4701 		if (dev->written)
4702 			s->written++;
4703 		/* Prefer to use the replacement for reads, but only
4704 		 * if it is recovered enough and has no bad blocks.
4705 		 */
4706 		rdev = conf->disks[i].replacement;
4707 		if (rdev && !test_bit(Faulty, &rdev->flags) &&
4708 		    rdev->recovery_offset >= sh->sector + RAID5_STRIPE_SECTORS(conf) &&
4709 		    !rdev_has_badblock(rdev, sh->sector,
4710 				       RAID5_STRIPE_SECTORS(conf)))
4711 			set_bit(R5_ReadRepl, &dev->flags);
4712 		else {
4713 			if (rdev && !test_bit(Faulty, &rdev->flags))
4714 				set_bit(R5_NeedReplace, &dev->flags);
4715 			else
4716 				clear_bit(R5_NeedReplace, &dev->flags);
4717 			rdev = conf->disks[i].rdev;
4718 			clear_bit(R5_ReadRepl, &dev->flags);
4719 		}
4720 		if (rdev && test_bit(Faulty, &rdev->flags))
4721 			rdev = NULL;
4722 		if (rdev) {
4723 			is_bad = rdev_has_badblock(rdev, sh->sector,
4724 						   RAID5_STRIPE_SECTORS(conf));
4725 			if (s->blocked_rdev == NULL
4726 			    && (test_bit(Blocked, &rdev->flags)
4727 				|| is_bad < 0)) {
4728 				if (is_bad < 0)
4729 					set_bit(BlockedBadBlocks,
4730 						&rdev->flags);
4731 				s->blocked_rdev = rdev;
4732 				atomic_inc(&rdev->nr_pending);
4733 			}
4734 		}
4735 		clear_bit(R5_Insync, &dev->flags);
4736 		if (!rdev)
4737 			/* Not in-sync */;
4738 		else if (is_bad) {
4739 			/* also not in-sync */
4740 			if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4741 			    test_bit(R5_UPTODATE, &dev->flags)) {
4742 				/* treat as in-sync, but with a read error
4743 				 * which we can now try to correct
4744 				 */
4745 				set_bit(R5_Insync, &dev->flags);
4746 				set_bit(R5_ReadError, &dev->flags);
4747 			}
4748 		} else if (test_bit(In_sync, &rdev->flags))
4749 			set_bit(R5_Insync, &dev->flags);
4750 		else if (sh->sector + RAID5_STRIPE_SECTORS(conf) <= rdev->recovery_offset)
4751 			/* in sync if before recovery_offset */
4752 			set_bit(R5_Insync, &dev->flags);
4753 		else if (test_bit(R5_UPTODATE, &dev->flags) &&
4754 			 test_bit(R5_Expanded, &dev->flags))
4755 			/* If we've reshaped into here, we assume it is Insync.
4756 			 * We will shortly update recovery_offset to make
4757 			 * it official.
4758 			 */
4759 			set_bit(R5_Insync, &dev->flags);
4760 
4761 		if (test_bit(R5_WriteError, &dev->flags)) {
4762 			/* This flag does not apply to '.replacement'
4763 			 * only to .rdev, so make sure to check that*/
4764 			struct md_rdev *rdev2 = conf->disks[i].rdev;
4765 
4766 			if (rdev2 == rdev)
4767 				clear_bit(R5_Insync, &dev->flags);
4768 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4769 				s->handle_bad_blocks = 1;
4770 				atomic_inc(&rdev2->nr_pending);
4771 			} else
4772 				clear_bit(R5_WriteError, &dev->flags);
4773 		}
4774 		if (test_bit(R5_MadeGood, &dev->flags)) {
4775 			/* This flag does not apply to '.replacement'
4776 			 * only to .rdev, so make sure to check that*/
4777 			struct md_rdev *rdev2 = conf->disks[i].rdev;
4778 
4779 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4780 				s->handle_bad_blocks = 1;
4781 				atomic_inc(&rdev2->nr_pending);
4782 			} else
4783 				clear_bit(R5_MadeGood, &dev->flags);
4784 		}
4785 		if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4786 			struct md_rdev *rdev2 = conf->disks[i].replacement;
4787 
4788 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4789 				s->handle_bad_blocks = 1;
4790 				atomic_inc(&rdev2->nr_pending);
4791 			} else
4792 				clear_bit(R5_MadeGoodRepl, &dev->flags);
4793 		}
4794 		if (!test_bit(R5_Insync, &dev->flags)) {
4795 			/* The ReadError flag will just be confusing now */
4796 			clear_bit(R5_ReadError, &dev->flags);
4797 			clear_bit(R5_ReWrite, &dev->flags);
4798 		}
4799 		if (test_bit(R5_ReadError, &dev->flags))
4800 			clear_bit(R5_Insync, &dev->flags);
4801 		if (!test_bit(R5_Insync, &dev->flags)) {
4802 			if (s->failed < 2)
4803 				s->failed_num[s->failed] = i;
4804 			s->failed++;
4805 			if (rdev && !test_bit(Faulty, &rdev->flags))
4806 				do_recovery = 1;
4807 			else if (!rdev) {
4808 				rdev = conf->disks[i].replacement;
4809 				if (rdev && !test_bit(Faulty, &rdev->flags))
4810 					do_recovery = 1;
4811 			}
4812 		}
4813 
4814 		if (test_bit(R5_InJournal, &dev->flags))
4815 			s->injournal++;
4816 		if (test_bit(R5_InJournal, &dev->flags) && dev->written)
4817 			s->just_cached++;
4818 	}
4819 	if (test_bit(STRIPE_SYNCING, &sh->state)) {
4820 		/* If there is a failed device being replaced,
4821 		 *     we must be recovering.
4822 		 * else if we are after recovery_cp, we must be syncing
4823 		 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4824 		 * else we can only be replacing
4825 		 * sync and recovery both need to read all devices, and so
4826 		 * use the same flag.
4827 		 */
4828 		if (do_recovery ||
4829 		    sh->sector >= conf->mddev->recovery_cp ||
4830 		    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4831 			s->syncing = 1;
4832 		else
4833 			s->replacing = 1;
4834 	}
4835 }
4836 
4837 /*
4838  * Return '1' if this is a member of batch, or '0' if it is a lone stripe or
4839  * a head which can now be handled.
4840  */
4841 static int clear_batch_ready(struct stripe_head *sh)
4842 {
4843 	struct stripe_head *tmp;
4844 	if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4845 		return (sh->batch_head && sh->batch_head != sh);
4846 	spin_lock(&sh->stripe_lock);
4847 	if (!sh->batch_head) {
4848 		spin_unlock(&sh->stripe_lock);
4849 		return 0;
4850 	}
4851 
4852 	/*
4853 	 * this stripe could be added to a batch list before we check
4854 	 * BATCH_READY, skips it
4855 	 */
4856 	if (sh->batch_head != sh) {
4857 		spin_unlock(&sh->stripe_lock);
4858 		return 1;
4859 	}
4860 	spin_lock(&sh->batch_lock);
4861 	list_for_each_entry(tmp, &sh->batch_list, batch_list)
4862 		clear_bit(STRIPE_BATCH_READY, &tmp->state);
4863 	spin_unlock(&sh->batch_lock);
4864 	spin_unlock(&sh->stripe_lock);
4865 
4866 	/*
4867 	 * BATCH_READY is cleared, no new stripes can be added.
4868 	 * batch_list can be accessed without lock
4869 	 */
4870 	return 0;
4871 }
4872 
4873 static void break_stripe_batch_list(struct stripe_head *head_sh,
4874 				    unsigned long handle_flags)
4875 {
4876 	struct stripe_head *sh, *next;
4877 	int i;
4878 	int do_wakeup = 0;
4879 
4880 	list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4881 
4882 		list_del_init(&sh->batch_list);
4883 
4884 		WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4885 					  (1 << STRIPE_SYNCING) |
4886 					  (1 << STRIPE_REPLACED) |
4887 					  (1 << STRIPE_DELAYED) |
4888 					  (1 << STRIPE_BIT_DELAY) |
4889 					  (1 << STRIPE_FULL_WRITE) |
4890 					  (1 << STRIPE_BIOFILL_RUN) |
4891 					  (1 << STRIPE_COMPUTE_RUN)  |
4892 					  (1 << STRIPE_DISCARD) |
4893 					  (1 << STRIPE_BATCH_READY) |
4894 					  (1 << STRIPE_BATCH_ERR) |
4895 					  (1 << STRIPE_BITMAP_PENDING)),
4896 			"stripe state: %lx\n", sh->state);
4897 		WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4898 					      (1 << STRIPE_REPLACED)),
4899 			"head stripe state: %lx\n", head_sh->state);
4900 
4901 		set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4902 					    (1 << STRIPE_PREREAD_ACTIVE) |
4903 					    (1 << STRIPE_DEGRADED) |
4904 					    (1 << STRIPE_ON_UNPLUG_LIST)),
4905 			      head_sh->state & (1 << STRIPE_INSYNC));
4906 
4907 		sh->check_state = head_sh->check_state;
4908 		sh->reconstruct_state = head_sh->reconstruct_state;
4909 		spin_lock_irq(&sh->stripe_lock);
4910 		sh->batch_head = NULL;
4911 		spin_unlock_irq(&sh->stripe_lock);
4912 		for (i = 0; i < sh->disks; i++) {
4913 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4914 				do_wakeup = 1;
4915 			sh->dev[i].flags = head_sh->dev[i].flags &
4916 				(~((1 << R5_WriteError) | (1 << R5_Overlap)));
4917 		}
4918 		if (handle_flags == 0 ||
4919 		    sh->state & handle_flags)
4920 			set_bit(STRIPE_HANDLE, &sh->state);
4921 		raid5_release_stripe(sh);
4922 	}
4923 	spin_lock_irq(&head_sh->stripe_lock);
4924 	head_sh->batch_head = NULL;
4925 	spin_unlock_irq(&head_sh->stripe_lock);
4926 	for (i = 0; i < head_sh->disks; i++)
4927 		if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4928 			do_wakeup = 1;
4929 	if (head_sh->state & handle_flags)
4930 		set_bit(STRIPE_HANDLE, &head_sh->state);
4931 
4932 	if (do_wakeup)
4933 		wake_up(&head_sh->raid_conf->wait_for_overlap);
4934 }
4935 
4936 static void handle_stripe(struct stripe_head *sh)
4937 {
4938 	struct stripe_head_state s;
4939 	struct r5conf *conf = sh->raid_conf;
4940 	int i;
4941 	int prexor;
4942 	int disks = sh->disks;
4943 	struct r5dev *pdev, *qdev;
4944 
4945 	clear_bit(STRIPE_HANDLE, &sh->state);
4946 
4947 	/*
4948 	 * handle_stripe should not continue handle the batched stripe, only
4949 	 * the head of batch list or lone stripe can continue. Otherwise we
4950 	 * could see break_stripe_batch_list warns about the STRIPE_ACTIVE
4951 	 * is set for the batched stripe.
4952 	 */
4953 	if (clear_batch_ready(sh))
4954 		return;
4955 
4956 	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4957 		/* already being handled, ensure it gets handled
4958 		 * again when current action finishes */
4959 		set_bit(STRIPE_HANDLE, &sh->state);
4960 		return;
4961 	}
4962 
4963 	if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4964 		break_stripe_batch_list(sh, 0);
4965 
4966 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4967 		spin_lock(&sh->stripe_lock);
4968 		/*
4969 		 * Cannot process 'sync' concurrently with 'discard'.
4970 		 * Flush data in r5cache before 'sync'.
4971 		 */
4972 		if (!test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) &&
4973 		    !test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state) &&
4974 		    !test_bit(STRIPE_DISCARD, &sh->state) &&
4975 		    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4976 			set_bit(STRIPE_SYNCING, &sh->state);
4977 			clear_bit(STRIPE_INSYNC, &sh->state);
4978 			clear_bit(STRIPE_REPLACED, &sh->state);
4979 		}
4980 		spin_unlock(&sh->stripe_lock);
4981 	}
4982 	clear_bit(STRIPE_DELAYED, &sh->state);
4983 
4984 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4985 		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4986 	       (unsigned long long)sh->sector, sh->state,
4987 	       atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4988 	       sh->check_state, sh->reconstruct_state);
4989 
4990 	analyse_stripe(sh, &s);
4991 
4992 	if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
4993 		goto finish;
4994 
4995 	if (s.handle_bad_blocks ||
4996 	    test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) {
4997 		set_bit(STRIPE_HANDLE, &sh->state);
4998 		goto finish;
4999 	}
5000 
5001 	if (unlikely(s.blocked_rdev)) {
5002 		if (s.syncing || s.expanding || s.expanded ||
5003 		    s.replacing || s.to_write || s.written) {
5004 			set_bit(STRIPE_HANDLE, &sh->state);
5005 			goto finish;
5006 		}
5007 		/* There is nothing for the blocked_rdev to block */
5008 		rdev_dec_pending(s.blocked_rdev, conf->mddev);
5009 		s.blocked_rdev = NULL;
5010 	}
5011 
5012 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
5013 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
5014 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
5015 	}
5016 
5017 	pr_debug("locked=%d uptodate=%d to_read=%d"
5018 	       " to_write=%d failed=%d failed_num=%d,%d\n",
5019 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
5020 	       s.failed_num[0], s.failed_num[1]);
5021 	/*
5022 	 * check if the array has lost more than max_degraded devices and,
5023 	 * if so, some requests might need to be failed.
5024 	 *
5025 	 * When journal device failed (log_failed), we will only process
5026 	 * the stripe if there is data need write to raid disks
5027 	 */
5028 	if (s.failed > conf->max_degraded ||
5029 	    (s.log_failed && s.injournal == 0)) {
5030 		sh->check_state = 0;
5031 		sh->reconstruct_state = 0;
5032 		break_stripe_batch_list(sh, 0);
5033 		if (s.to_read+s.to_write+s.written)
5034 			handle_failed_stripe(conf, sh, &s, disks);
5035 		if (s.syncing + s.replacing)
5036 			handle_failed_sync(conf, sh, &s);
5037 	}
5038 
5039 	/* Now we check to see if any write operations have recently
5040 	 * completed
5041 	 */
5042 	prexor = 0;
5043 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
5044 		prexor = 1;
5045 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
5046 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
5047 		sh->reconstruct_state = reconstruct_state_idle;
5048 
5049 		/* All the 'written' buffers and the parity block are ready to
5050 		 * be written back to disk
5051 		 */
5052 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
5053 		       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
5054 		BUG_ON(sh->qd_idx >= 0 &&
5055 		       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
5056 		       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
5057 		for (i = disks; i--; ) {
5058 			struct r5dev *dev = &sh->dev[i];
5059 			if (test_bit(R5_LOCKED, &dev->flags) &&
5060 				(i == sh->pd_idx || i == sh->qd_idx ||
5061 				 dev->written || test_bit(R5_InJournal,
5062 							  &dev->flags))) {
5063 				pr_debug("Writing block %d\n", i);
5064 				set_bit(R5_Wantwrite, &dev->flags);
5065 				if (prexor)
5066 					continue;
5067 				if (s.failed > 1)
5068 					continue;
5069 				if (!test_bit(R5_Insync, &dev->flags) ||
5070 				    ((i == sh->pd_idx || i == sh->qd_idx)  &&
5071 				     s.failed == 0))
5072 					set_bit(STRIPE_INSYNC, &sh->state);
5073 			}
5074 		}
5075 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5076 			s.dec_preread_active = 1;
5077 	}
5078 
5079 	/*
5080 	 * might be able to return some write requests if the parity blocks
5081 	 * are safe, or on a failed drive
5082 	 */
5083 	pdev = &sh->dev[sh->pd_idx];
5084 	s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
5085 		|| (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
5086 	qdev = &sh->dev[sh->qd_idx];
5087 	s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
5088 		|| (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
5089 		|| conf->level < 6;
5090 
5091 	if (s.written &&
5092 	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
5093 			     && !test_bit(R5_LOCKED, &pdev->flags)
5094 			     && (test_bit(R5_UPTODATE, &pdev->flags) ||
5095 				 test_bit(R5_Discard, &pdev->flags))))) &&
5096 	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
5097 			     && !test_bit(R5_LOCKED, &qdev->flags)
5098 			     && (test_bit(R5_UPTODATE, &qdev->flags) ||
5099 				 test_bit(R5_Discard, &qdev->flags))))))
5100 		handle_stripe_clean_event(conf, sh, disks);
5101 
5102 	if (s.just_cached)
5103 		r5c_handle_cached_data_endio(conf, sh, disks);
5104 	log_stripe_write_finished(sh);
5105 
5106 	/* Now we might consider reading some blocks, either to check/generate
5107 	 * parity, or to satisfy requests
5108 	 * or to load a block that is being partially written.
5109 	 */
5110 	if (s.to_read || s.non_overwrite
5111 	    || (s.to_write && s.failed)
5112 	    || (s.syncing && (s.uptodate + s.compute < disks))
5113 	    || s.replacing
5114 	    || s.expanding)
5115 		handle_stripe_fill(sh, &s, disks);
5116 
5117 	/*
5118 	 * When the stripe finishes full journal write cycle (write to journal
5119 	 * and raid disk), this is the clean up procedure so it is ready for
5120 	 * next operation.
5121 	 */
5122 	r5c_finish_stripe_write_out(conf, sh, &s);
5123 
5124 	/*
5125 	 * Now to consider new write requests, cache write back and what else,
5126 	 * if anything should be read.  We do not handle new writes when:
5127 	 * 1/ A 'write' operation (copy+xor) is already in flight.
5128 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
5129 	 *    block.
5130 	 * 3/ A r5c cache log write is in flight.
5131 	 */
5132 
5133 	if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
5134 		if (!r5c_is_writeback(conf->log)) {
5135 			if (s.to_write)
5136 				handle_stripe_dirtying(conf, sh, &s, disks);
5137 		} else { /* write back cache */
5138 			int ret = 0;
5139 
5140 			/* First, try handle writes in caching phase */
5141 			if (s.to_write)
5142 				ret = r5c_try_caching_write(conf, sh, &s,
5143 							    disks);
5144 			/*
5145 			 * If caching phase failed: ret == -EAGAIN
5146 			 *    OR
5147 			 * stripe under reclaim: !caching && injournal
5148 			 *
5149 			 * fall back to handle_stripe_dirtying()
5150 			 */
5151 			if (ret == -EAGAIN ||
5152 			    /* stripe under reclaim: !caching && injournal */
5153 			    (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
5154 			     s.injournal > 0)) {
5155 				ret = handle_stripe_dirtying(conf, sh, &s,
5156 							     disks);
5157 				if (ret == -EAGAIN)
5158 					goto finish;
5159 			}
5160 		}
5161 	}
5162 
5163 	/* maybe we need to check and possibly fix the parity for this stripe
5164 	 * Any reads will already have been scheduled, so we just see if enough
5165 	 * data is available.  The parity check is held off while parity
5166 	 * dependent operations are in flight.
5167 	 */
5168 	if (sh->check_state ||
5169 	    (s.syncing && s.locked == 0 &&
5170 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
5171 	     !test_bit(STRIPE_INSYNC, &sh->state))) {
5172 		if (conf->level == 6)
5173 			handle_parity_checks6(conf, sh, &s, disks);
5174 		else
5175 			handle_parity_checks5(conf, sh, &s, disks);
5176 	}
5177 
5178 	if ((s.replacing || s.syncing) && s.locked == 0
5179 	    && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
5180 	    && !test_bit(STRIPE_REPLACED, &sh->state)) {
5181 		/* Write out to replacement devices where possible */
5182 		for (i = 0; i < conf->raid_disks; i++)
5183 			if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
5184 				WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
5185 				set_bit(R5_WantReplace, &sh->dev[i].flags);
5186 				set_bit(R5_LOCKED, &sh->dev[i].flags);
5187 				s.locked++;
5188 			}
5189 		if (s.replacing)
5190 			set_bit(STRIPE_INSYNC, &sh->state);
5191 		set_bit(STRIPE_REPLACED, &sh->state);
5192 	}
5193 	if ((s.syncing || s.replacing) && s.locked == 0 &&
5194 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
5195 	    test_bit(STRIPE_INSYNC, &sh->state)) {
5196 		md_done_sync(conf->mddev, RAID5_STRIPE_SECTORS(conf), 1);
5197 		clear_bit(STRIPE_SYNCING, &sh->state);
5198 		if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
5199 			wake_up(&conf->wait_for_overlap);
5200 	}
5201 
5202 	/* If the failed drives are just a ReadError, then we might need
5203 	 * to progress the repair/check process
5204 	 */
5205 	if (s.failed <= conf->max_degraded && !conf->mddev->ro)
5206 		for (i = 0; i < s.failed; i++) {
5207 			struct r5dev *dev = &sh->dev[s.failed_num[i]];
5208 			if (test_bit(R5_ReadError, &dev->flags)
5209 			    && !test_bit(R5_LOCKED, &dev->flags)
5210 			    && test_bit(R5_UPTODATE, &dev->flags)
5211 				) {
5212 				if (!test_bit(R5_ReWrite, &dev->flags)) {
5213 					set_bit(R5_Wantwrite, &dev->flags);
5214 					set_bit(R5_ReWrite, &dev->flags);
5215 				} else
5216 					/* let's read it back */
5217 					set_bit(R5_Wantread, &dev->flags);
5218 				set_bit(R5_LOCKED, &dev->flags);
5219 				s.locked++;
5220 			}
5221 		}
5222 
5223 	/* Finish reconstruct operations initiated by the expansion process */
5224 	if (sh->reconstruct_state == reconstruct_state_result) {
5225 		struct stripe_head *sh_src
5226 			= raid5_get_active_stripe(conf, NULL, sh->sector,
5227 					R5_GAS_PREVIOUS | R5_GAS_NOBLOCK |
5228 					R5_GAS_NOQUIESCE);
5229 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
5230 			/* sh cannot be written until sh_src has been read.
5231 			 * so arrange for sh to be delayed a little
5232 			 */
5233 			set_bit(STRIPE_DELAYED, &sh->state);
5234 			set_bit(STRIPE_HANDLE, &sh->state);
5235 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
5236 					      &sh_src->state))
5237 				atomic_inc(&conf->preread_active_stripes);
5238 			raid5_release_stripe(sh_src);
5239 			goto finish;
5240 		}
5241 		if (sh_src)
5242 			raid5_release_stripe(sh_src);
5243 
5244 		sh->reconstruct_state = reconstruct_state_idle;
5245 		clear_bit(STRIPE_EXPANDING, &sh->state);
5246 		for (i = conf->raid_disks; i--; ) {
5247 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
5248 			set_bit(R5_LOCKED, &sh->dev[i].flags);
5249 			s.locked++;
5250 		}
5251 	}
5252 
5253 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
5254 	    !sh->reconstruct_state) {
5255 		/* Need to write out all blocks after computing parity */
5256 		sh->disks = conf->raid_disks;
5257 		stripe_set_idx(sh->sector, conf, 0, sh);
5258 		schedule_reconstruction(sh, &s, 1, 1);
5259 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
5260 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
5261 		atomic_dec(&conf->reshape_stripes);
5262 		wake_up(&conf->wait_for_overlap);
5263 		md_done_sync(conf->mddev, RAID5_STRIPE_SECTORS(conf), 1);
5264 	}
5265 
5266 	if (s.expanding && s.locked == 0 &&
5267 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
5268 		handle_stripe_expansion(conf, sh);
5269 
5270 finish:
5271 	/* wait for this device to become unblocked */
5272 	if (unlikely(s.blocked_rdev)) {
5273 		if (conf->mddev->external)
5274 			md_wait_for_blocked_rdev(s.blocked_rdev,
5275 						 conf->mddev);
5276 		else
5277 			/* Internal metadata will immediately
5278 			 * be written by raid5d, so we don't
5279 			 * need to wait here.
5280 			 */
5281 			rdev_dec_pending(s.blocked_rdev,
5282 					 conf->mddev);
5283 	}
5284 
5285 	if (s.handle_bad_blocks)
5286 		for (i = disks; i--; ) {
5287 			struct md_rdev *rdev;
5288 			struct r5dev *dev = &sh->dev[i];
5289 			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
5290 				/* We own a safe reference to the rdev */
5291 				rdev = conf->disks[i].rdev;
5292 				if (!rdev_set_badblocks(rdev, sh->sector,
5293 							RAID5_STRIPE_SECTORS(conf), 0))
5294 					md_error(conf->mddev, rdev);
5295 				rdev_dec_pending(rdev, conf->mddev);
5296 			}
5297 			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
5298 				rdev = conf->disks[i].rdev;
5299 				rdev_clear_badblocks(rdev, sh->sector,
5300 						     RAID5_STRIPE_SECTORS(conf), 0);
5301 				rdev_dec_pending(rdev, conf->mddev);
5302 			}
5303 			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
5304 				rdev = conf->disks[i].replacement;
5305 				if (!rdev)
5306 					/* rdev have been moved down */
5307 					rdev = conf->disks[i].rdev;
5308 				rdev_clear_badblocks(rdev, sh->sector,
5309 						     RAID5_STRIPE_SECTORS(conf), 0);
5310 				rdev_dec_pending(rdev, conf->mddev);
5311 			}
5312 		}
5313 
5314 	if (s.ops_request)
5315 		raid_run_ops(sh, s.ops_request);
5316 
5317 	ops_run_io(sh, &s);
5318 
5319 	if (s.dec_preread_active) {
5320 		/* We delay this until after ops_run_io so that if make_request
5321 		 * is waiting on a flush, it won't continue until the writes
5322 		 * have actually been submitted.
5323 		 */
5324 		atomic_dec(&conf->preread_active_stripes);
5325 		if (atomic_read(&conf->preread_active_stripes) <
5326 		    IO_THRESHOLD)
5327 			md_wakeup_thread(conf->mddev->thread);
5328 	}
5329 
5330 	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
5331 }
5332 
5333 static void raid5_activate_delayed(struct r5conf *conf)
5334 	__must_hold(&conf->device_lock)
5335 {
5336 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
5337 		while (!list_empty(&conf->delayed_list)) {
5338 			struct list_head *l = conf->delayed_list.next;
5339 			struct stripe_head *sh;
5340 			sh = list_entry(l, struct stripe_head, lru);
5341 			list_del_init(l);
5342 			clear_bit(STRIPE_DELAYED, &sh->state);
5343 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5344 				atomic_inc(&conf->preread_active_stripes);
5345 			list_add_tail(&sh->lru, &conf->hold_list);
5346 			raid5_wakeup_stripe_thread(sh);
5347 		}
5348 	}
5349 }
5350 
5351 static void activate_bit_delay(struct r5conf *conf,
5352 		struct list_head *temp_inactive_list)
5353 	__must_hold(&conf->device_lock)
5354 {
5355 	struct list_head head;
5356 	list_add(&head, &conf->bitmap_list);
5357 	list_del_init(&conf->bitmap_list);
5358 	while (!list_empty(&head)) {
5359 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
5360 		int hash;
5361 		list_del_init(&sh->lru);
5362 		atomic_inc(&sh->count);
5363 		hash = sh->hash_lock_index;
5364 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
5365 	}
5366 }
5367 
5368 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
5369 {
5370 	struct r5conf *conf = mddev->private;
5371 	sector_t sector = bio->bi_iter.bi_sector;
5372 	unsigned int chunk_sectors;
5373 	unsigned int bio_sectors = bio_sectors(bio);
5374 
5375 	chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
5376 	return  chunk_sectors >=
5377 		((sector & (chunk_sectors - 1)) + bio_sectors);
5378 }
5379 
5380 /*
5381  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
5382  *  later sampled by raid5d.
5383  */
5384 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
5385 {
5386 	unsigned long flags;
5387 
5388 	spin_lock_irqsave(&conf->device_lock, flags);
5389 
5390 	bi->bi_next = conf->retry_read_aligned_list;
5391 	conf->retry_read_aligned_list = bi;
5392 
5393 	spin_unlock_irqrestore(&conf->device_lock, flags);
5394 	md_wakeup_thread(conf->mddev->thread);
5395 }
5396 
5397 static struct bio *remove_bio_from_retry(struct r5conf *conf,
5398 					 unsigned int *offset)
5399 {
5400 	struct bio *bi;
5401 
5402 	bi = conf->retry_read_aligned;
5403 	if (bi) {
5404 		*offset = conf->retry_read_offset;
5405 		conf->retry_read_aligned = NULL;
5406 		return bi;
5407 	}
5408 	bi = conf->retry_read_aligned_list;
5409 	if(bi) {
5410 		conf->retry_read_aligned_list = bi->bi_next;
5411 		bi->bi_next = NULL;
5412 		*offset = 0;
5413 	}
5414 
5415 	return bi;
5416 }
5417 
5418 /*
5419  *  The "raid5_align_endio" should check if the read succeeded and if it
5420  *  did, call bio_endio on the original bio (having bio_put the new bio
5421  *  first).
5422  *  If the read failed..
5423  */
5424 static void raid5_align_endio(struct bio *bi)
5425 {
5426 	struct bio *raid_bi = bi->bi_private;
5427 	struct md_rdev *rdev = (void *)raid_bi->bi_next;
5428 	struct mddev *mddev = rdev->mddev;
5429 	struct r5conf *conf = mddev->private;
5430 	blk_status_t error = bi->bi_status;
5431 
5432 	bio_put(bi);
5433 	raid_bi->bi_next = NULL;
5434 	rdev_dec_pending(rdev, conf->mddev);
5435 
5436 	if (!error) {
5437 		bio_endio(raid_bi);
5438 		if (atomic_dec_and_test(&conf->active_aligned_reads))
5439 			wake_up(&conf->wait_for_quiescent);
5440 		return;
5441 	}
5442 
5443 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
5444 
5445 	add_bio_to_retry(raid_bi, conf);
5446 }
5447 
5448 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
5449 {
5450 	struct r5conf *conf = mddev->private;
5451 	struct bio *align_bio;
5452 	struct md_rdev *rdev;
5453 	sector_t sector, end_sector;
5454 	int dd_idx;
5455 	bool did_inc;
5456 
5457 	if (!in_chunk_boundary(mddev, raid_bio)) {
5458 		pr_debug("%s: non aligned\n", __func__);
5459 		return 0;
5460 	}
5461 
5462 	sector = raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector, 0,
5463 				      &dd_idx, NULL);
5464 	end_sector = sector + bio_sectors(raid_bio);
5465 
5466 	if (r5c_big_stripe_cached(conf, sector))
5467 		return 0;
5468 
5469 	rdev = conf->disks[dd_idx].replacement;
5470 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
5471 	    rdev->recovery_offset < end_sector) {
5472 		rdev = conf->disks[dd_idx].rdev;
5473 		if (!rdev)
5474 			return 0;
5475 		if (test_bit(Faulty, &rdev->flags) ||
5476 		    !(test_bit(In_sync, &rdev->flags) ||
5477 		      rdev->recovery_offset >= end_sector))
5478 			return 0;
5479 	}
5480 
5481 	atomic_inc(&rdev->nr_pending);
5482 
5483 	if (rdev_has_badblock(rdev, sector, bio_sectors(raid_bio))) {
5484 		rdev_dec_pending(rdev, mddev);
5485 		return 0;
5486 	}
5487 
5488 	md_account_bio(mddev, &raid_bio);
5489 	raid_bio->bi_next = (void *)rdev;
5490 
5491 	align_bio = bio_alloc_clone(rdev->bdev, raid_bio, GFP_NOIO,
5492 				    &mddev->bio_set);
5493 	align_bio->bi_end_io = raid5_align_endio;
5494 	align_bio->bi_private = raid_bio;
5495 	align_bio->bi_iter.bi_sector = sector;
5496 
5497 	/* No reshape active, so we can trust rdev->data_offset */
5498 	align_bio->bi_iter.bi_sector += rdev->data_offset;
5499 
5500 	did_inc = false;
5501 	if (conf->quiesce == 0) {
5502 		atomic_inc(&conf->active_aligned_reads);
5503 		did_inc = true;
5504 	}
5505 	/* need a memory barrier to detect the race with raid5_quiesce() */
5506 	if (!did_inc || smp_load_acquire(&conf->quiesce) != 0) {
5507 		/* quiesce is in progress, so we need to undo io activation and wait
5508 		 * for it to finish
5509 		 */
5510 		if (did_inc && atomic_dec_and_test(&conf->active_aligned_reads))
5511 			wake_up(&conf->wait_for_quiescent);
5512 		spin_lock_irq(&conf->device_lock);
5513 		wait_event_lock_irq(conf->wait_for_quiescent, conf->quiesce == 0,
5514 				    conf->device_lock);
5515 		atomic_inc(&conf->active_aligned_reads);
5516 		spin_unlock_irq(&conf->device_lock);
5517 	}
5518 
5519 	mddev_trace_remap(mddev, align_bio, raid_bio->bi_iter.bi_sector);
5520 	submit_bio_noacct(align_bio);
5521 	return 1;
5522 }
5523 
5524 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
5525 {
5526 	struct bio *split;
5527 	sector_t sector = raid_bio->bi_iter.bi_sector;
5528 	unsigned chunk_sects = mddev->chunk_sectors;
5529 	unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
5530 
5531 	if (sectors < bio_sectors(raid_bio)) {
5532 		struct r5conf *conf = mddev->private;
5533 		split = bio_split(raid_bio, sectors, GFP_NOIO, &conf->bio_split);
5534 		bio_chain(split, raid_bio);
5535 		submit_bio_noacct(raid_bio);
5536 		raid_bio = split;
5537 	}
5538 
5539 	if (!raid5_read_one_chunk(mddev, raid_bio))
5540 		return raid_bio;
5541 
5542 	return NULL;
5543 }
5544 
5545 /* __get_priority_stripe - get the next stripe to process
5546  *
5547  * Full stripe writes are allowed to pass preread active stripes up until
5548  * the bypass_threshold is exceeded.  In general the bypass_count
5549  * increments when the handle_list is handled before the hold_list; however, it
5550  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
5551  * stripe with in flight i/o.  The bypass_count will be reset when the
5552  * head of the hold_list has changed, i.e. the head was promoted to the
5553  * handle_list.
5554  */
5555 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
5556 	__must_hold(&conf->device_lock)
5557 {
5558 	struct stripe_head *sh, *tmp;
5559 	struct list_head *handle_list = NULL;
5560 	struct r5worker_group *wg;
5561 	bool second_try = !r5c_is_writeback(conf->log) &&
5562 		!r5l_log_disk_error(conf);
5563 	bool try_loprio = test_bit(R5C_LOG_TIGHT, &conf->cache_state) ||
5564 		r5l_log_disk_error(conf);
5565 
5566 again:
5567 	wg = NULL;
5568 	sh = NULL;
5569 	if (conf->worker_cnt_per_group == 0) {
5570 		handle_list = try_loprio ? &conf->loprio_list :
5571 					&conf->handle_list;
5572 	} else if (group != ANY_GROUP) {
5573 		handle_list = try_loprio ? &conf->worker_groups[group].loprio_list :
5574 				&conf->worker_groups[group].handle_list;
5575 		wg = &conf->worker_groups[group];
5576 	} else {
5577 		int i;
5578 		for (i = 0; i < conf->group_cnt; i++) {
5579 			handle_list = try_loprio ? &conf->worker_groups[i].loprio_list :
5580 				&conf->worker_groups[i].handle_list;
5581 			wg = &conf->worker_groups[i];
5582 			if (!list_empty(handle_list))
5583 				break;
5584 		}
5585 	}
5586 
5587 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
5588 		  __func__,
5589 		  list_empty(handle_list) ? "empty" : "busy",
5590 		  list_empty(&conf->hold_list) ? "empty" : "busy",
5591 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
5592 
5593 	if (!list_empty(handle_list)) {
5594 		sh = list_entry(handle_list->next, typeof(*sh), lru);
5595 
5596 		if (list_empty(&conf->hold_list))
5597 			conf->bypass_count = 0;
5598 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
5599 			if (conf->hold_list.next == conf->last_hold)
5600 				conf->bypass_count++;
5601 			else {
5602 				conf->last_hold = conf->hold_list.next;
5603 				conf->bypass_count -= conf->bypass_threshold;
5604 				if (conf->bypass_count < 0)
5605 					conf->bypass_count = 0;
5606 			}
5607 		}
5608 	} else if (!list_empty(&conf->hold_list) &&
5609 		   ((conf->bypass_threshold &&
5610 		     conf->bypass_count > conf->bypass_threshold) ||
5611 		    atomic_read(&conf->pending_full_writes) == 0)) {
5612 
5613 		list_for_each_entry(tmp, &conf->hold_list,  lru) {
5614 			if (conf->worker_cnt_per_group == 0 ||
5615 			    group == ANY_GROUP ||
5616 			    !cpu_online(tmp->cpu) ||
5617 			    cpu_to_group(tmp->cpu) == group) {
5618 				sh = tmp;
5619 				break;
5620 			}
5621 		}
5622 
5623 		if (sh) {
5624 			conf->bypass_count -= conf->bypass_threshold;
5625 			if (conf->bypass_count < 0)
5626 				conf->bypass_count = 0;
5627 		}
5628 		wg = NULL;
5629 	}
5630 
5631 	if (!sh) {
5632 		if (second_try)
5633 			return NULL;
5634 		second_try = true;
5635 		try_loprio = !try_loprio;
5636 		goto again;
5637 	}
5638 
5639 	if (wg) {
5640 		wg->stripes_cnt--;
5641 		sh->group = NULL;
5642 	}
5643 	list_del_init(&sh->lru);
5644 	BUG_ON(atomic_inc_return(&sh->count) != 1);
5645 	return sh;
5646 }
5647 
5648 struct raid5_plug_cb {
5649 	struct blk_plug_cb	cb;
5650 	struct list_head	list;
5651 	struct list_head	temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5652 };
5653 
5654 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5655 {
5656 	struct raid5_plug_cb *cb = container_of(
5657 		blk_cb, struct raid5_plug_cb, cb);
5658 	struct stripe_head *sh;
5659 	struct mddev *mddev = cb->cb.data;
5660 	struct r5conf *conf = mddev->private;
5661 	int cnt = 0;
5662 	int hash;
5663 
5664 	if (cb->list.next && !list_empty(&cb->list)) {
5665 		spin_lock_irq(&conf->device_lock);
5666 		while (!list_empty(&cb->list)) {
5667 			sh = list_first_entry(&cb->list, struct stripe_head, lru);
5668 			list_del_init(&sh->lru);
5669 			/*
5670 			 * avoid race release_stripe_plug() sees
5671 			 * STRIPE_ON_UNPLUG_LIST clear but the stripe
5672 			 * is still in our list
5673 			 */
5674 			smp_mb__before_atomic();
5675 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5676 			/*
5677 			 * STRIPE_ON_RELEASE_LIST could be set here. In that
5678 			 * case, the count is always > 1 here
5679 			 */
5680 			hash = sh->hash_lock_index;
5681 			__release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5682 			cnt++;
5683 		}
5684 		spin_unlock_irq(&conf->device_lock);
5685 	}
5686 	release_inactive_stripe_list(conf, cb->temp_inactive_list,
5687 				     NR_STRIPE_HASH_LOCKS);
5688 	if (!mddev_is_dm(mddev))
5689 		trace_block_unplug(mddev->gendisk->queue, cnt, !from_schedule);
5690 	kfree(cb);
5691 }
5692 
5693 static void release_stripe_plug(struct mddev *mddev,
5694 				struct stripe_head *sh)
5695 {
5696 	struct blk_plug_cb *blk_cb = blk_check_plugged(
5697 		raid5_unplug, mddev,
5698 		sizeof(struct raid5_plug_cb));
5699 	struct raid5_plug_cb *cb;
5700 
5701 	if (!blk_cb) {
5702 		raid5_release_stripe(sh);
5703 		return;
5704 	}
5705 
5706 	cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5707 
5708 	if (cb->list.next == NULL) {
5709 		int i;
5710 		INIT_LIST_HEAD(&cb->list);
5711 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5712 			INIT_LIST_HEAD(cb->temp_inactive_list + i);
5713 	}
5714 
5715 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5716 		list_add_tail(&sh->lru, &cb->list);
5717 	else
5718 		raid5_release_stripe(sh);
5719 }
5720 
5721 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5722 {
5723 	struct r5conf *conf = mddev->private;
5724 	sector_t logical_sector, last_sector;
5725 	struct stripe_head *sh;
5726 	int stripe_sectors;
5727 
5728 	/* We need to handle this when io_uring supports discard/trim */
5729 	if (WARN_ON_ONCE(bi->bi_opf & REQ_NOWAIT))
5730 		return;
5731 
5732 	if (mddev->reshape_position != MaxSector)
5733 		/* Skip discard while reshape is happening */
5734 		return;
5735 
5736 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
5737 	last_sector = bio_end_sector(bi);
5738 
5739 	bi->bi_next = NULL;
5740 
5741 	stripe_sectors = conf->chunk_sectors *
5742 		(conf->raid_disks - conf->max_degraded);
5743 	logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5744 					       stripe_sectors);
5745 	sector_div(last_sector, stripe_sectors);
5746 
5747 	logical_sector *= conf->chunk_sectors;
5748 	last_sector *= conf->chunk_sectors;
5749 
5750 	for (; logical_sector < last_sector;
5751 	     logical_sector += RAID5_STRIPE_SECTORS(conf)) {
5752 		DEFINE_WAIT(w);
5753 		int d;
5754 	again:
5755 		sh = raid5_get_active_stripe(conf, NULL, logical_sector, 0);
5756 		prepare_to_wait(&conf->wait_for_overlap, &w,
5757 				TASK_UNINTERRUPTIBLE);
5758 		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5759 		if (test_bit(STRIPE_SYNCING, &sh->state)) {
5760 			raid5_release_stripe(sh);
5761 			schedule();
5762 			goto again;
5763 		}
5764 		clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5765 		spin_lock_irq(&sh->stripe_lock);
5766 		for (d = 0; d < conf->raid_disks; d++) {
5767 			if (d == sh->pd_idx || d == sh->qd_idx)
5768 				continue;
5769 			if (sh->dev[d].towrite || sh->dev[d].toread) {
5770 				set_bit(R5_Overlap, &sh->dev[d].flags);
5771 				spin_unlock_irq(&sh->stripe_lock);
5772 				raid5_release_stripe(sh);
5773 				schedule();
5774 				goto again;
5775 			}
5776 		}
5777 		set_bit(STRIPE_DISCARD, &sh->state);
5778 		finish_wait(&conf->wait_for_overlap, &w);
5779 		sh->overwrite_disks = 0;
5780 		for (d = 0; d < conf->raid_disks; d++) {
5781 			if (d == sh->pd_idx || d == sh->qd_idx)
5782 				continue;
5783 			sh->dev[d].towrite = bi;
5784 			set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5785 			bio_inc_remaining(bi);
5786 			md_write_inc(mddev, bi);
5787 			sh->overwrite_disks++;
5788 		}
5789 		spin_unlock_irq(&sh->stripe_lock);
5790 		if (conf->mddev->bitmap) {
5791 			for (d = 0;
5792 			     d < conf->raid_disks - conf->max_degraded;
5793 			     d++)
5794 				md_bitmap_startwrite(mddev->bitmap,
5795 						     sh->sector,
5796 						     RAID5_STRIPE_SECTORS(conf),
5797 						     0);
5798 			sh->bm_seq = conf->seq_flush + 1;
5799 			set_bit(STRIPE_BIT_DELAY, &sh->state);
5800 		}
5801 
5802 		set_bit(STRIPE_HANDLE, &sh->state);
5803 		clear_bit(STRIPE_DELAYED, &sh->state);
5804 		if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5805 			atomic_inc(&conf->preread_active_stripes);
5806 		release_stripe_plug(mddev, sh);
5807 	}
5808 
5809 	bio_endio(bi);
5810 }
5811 
5812 static bool ahead_of_reshape(struct mddev *mddev, sector_t sector,
5813 			     sector_t reshape_sector)
5814 {
5815 	return mddev->reshape_backwards ? sector < reshape_sector :
5816 					  sector >= reshape_sector;
5817 }
5818 
5819 static bool range_ahead_of_reshape(struct mddev *mddev, sector_t min,
5820 				   sector_t max, sector_t reshape_sector)
5821 {
5822 	return mddev->reshape_backwards ? max < reshape_sector :
5823 					  min >= reshape_sector;
5824 }
5825 
5826 static bool stripe_ahead_of_reshape(struct mddev *mddev, struct r5conf *conf,
5827 				    struct stripe_head *sh)
5828 {
5829 	sector_t max_sector = 0, min_sector = MaxSector;
5830 	bool ret = false;
5831 	int dd_idx;
5832 
5833 	for (dd_idx = 0; dd_idx < sh->disks; dd_idx++) {
5834 		if (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
5835 			continue;
5836 
5837 		min_sector = min(min_sector, sh->dev[dd_idx].sector);
5838 		max_sector = max(max_sector, sh->dev[dd_idx].sector);
5839 	}
5840 
5841 	spin_lock_irq(&conf->device_lock);
5842 
5843 	if (!range_ahead_of_reshape(mddev, min_sector, max_sector,
5844 				     conf->reshape_progress))
5845 		/* mismatch, need to try again */
5846 		ret = true;
5847 
5848 	spin_unlock_irq(&conf->device_lock);
5849 
5850 	return ret;
5851 }
5852 
5853 static int add_all_stripe_bios(struct r5conf *conf,
5854 		struct stripe_request_ctx *ctx, struct stripe_head *sh,
5855 		struct bio *bi, int forwrite, int previous)
5856 {
5857 	int dd_idx;
5858 	int ret = 1;
5859 
5860 	spin_lock_irq(&sh->stripe_lock);
5861 
5862 	for (dd_idx = 0; dd_idx < sh->disks; dd_idx++) {
5863 		struct r5dev *dev = &sh->dev[dd_idx];
5864 
5865 		if (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
5866 			continue;
5867 
5868 		if (dev->sector < ctx->first_sector ||
5869 		    dev->sector >= ctx->last_sector)
5870 			continue;
5871 
5872 		if (stripe_bio_overlaps(sh, bi, dd_idx, forwrite)) {
5873 			set_bit(R5_Overlap, &dev->flags);
5874 			ret = 0;
5875 			continue;
5876 		}
5877 	}
5878 
5879 	if (!ret)
5880 		goto out;
5881 
5882 	for (dd_idx = 0; dd_idx < sh->disks; dd_idx++) {
5883 		struct r5dev *dev = &sh->dev[dd_idx];
5884 
5885 		if (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
5886 			continue;
5887 
5888 		if (dev->sector < ctx->first_sector ||
5889 		    dev->sector >= ctx->last_sector)
5890 			continue;
5891 
5892 		__add_stripe_bio(sh, bi, dd_idx, forwrite, previous);
5893 		clear_bit((dev->sector - ctx->first_sector) >>
5894 			  RAID5_STRIPE_SHIFT(conf), ctx->sectors_to_do);
5895 	}
5896 
5897 out:
5898 	spin_unlock_irq(&sh->stripe_lock);
5899 	return ret;
5900 }
5901 
5902 enum reshape_loc {
5903 	LOC_NO_RESHAPE,
5904 	LOC_AHEAD_OF_RESHAPE,
5905 	LOC_INSIDE_RESHAPE,
5906 	LOC_BEHIND_RESHAPE,
5907 };
5908 
5909 static enum reshape_loc get_reshape_loc(struct mddev *mddev,
5910 		struct r5conf *conf, sector_t logical_sector)
5911 {
5912 	sector_t reshape_progress, reshape_safe;
5913 	/*
5914 	 * Spinlock is needed as reshape_progress may be
5915 	 * 64bit on a 32bit platform, and so it might be
5916 	 * possible to see a half-updated value
5917 	 * Of course reshape_progress could change after
5918 	 * the lock is dropped, so once we get a reference
5919 	 * to the stripe that we think it is, we will have
5920 	 * to check again.
5921 	 */
5922 	spin_lock_irq(&conf->device_lock);
5923 	reshape_progress = conf->reshape_progress;
5924 	reshape_safe = conf->reshape_safe;
5925 	spin_unlock_irq(&conf->device_lock);
5926 	if (reshape_progress == MaxSector)
5927 		return LOC_NO_RESHAPE;
5928 	if (ahead_of_reshape(mddev, logical_sector, reshape_progress))
5929 		return LOC_AHEAD_OF_RESHAPE;
5930 	if (ahead_of_reshape(mddev, logical_sector, reshape_safe))
5931 		return LOC_INSIDE_RESHAPE;
5932 	return LOC_BEHIND_RESHAPE;
5933 }
5934 
5935 static enum stripe_result make_stripe_request(struct mddev *mddev,
5936 		struct r5conf *conf, struct stripe_request_ctx *ctx,
5937 		sector_t logical_sector, struct bio *bi)
5938 {
5939 	const int rw = bio_data_dir(bi);
5940 	enum stripe_result ret;
5941 	struct stripe_head *sh;
5942 	sector_t new_sector;
5943 	int previous = 0, flags = 0;
5944 	int seq, dd_idx;
5945 
5946 	seq = read_seqcount_begin(&conf->gen_lock);
5947 
5948 	if (unlikely(conf->reshape_progress != MaxSector)) {
5949 		enum reshape_loc loc = get_reshape_loc(mddev, conf,
5950 						       logical_sector);
5951 		if (loc == LOC_INSIDE_RESHAPE) {
5952 			ret = STRIPE_SCHEDULE_AND_RETRY;
5953 			goto out;
5954 		}
5955 		if (loc == LOC_AHEAD_OF_RESHAPE)
5956 			previous = 1;
5957 	}
5958 
5959 	new_sector = raid5_compute_sector(conf, logical_sector, previous,
5960 					  &dd_idx, NULL);
5961 	pr_debug("raid456: %s, sector %llu logical %llu\n", __func__,
5962 		 new_sector, logical_sector);
5963 
5964 	if (previous)
5965 		flags |= R5_GAS_PREVIOUS;
5966 	if (bi->bi_opf & REQ_RAHEAD)
5967 		flags |= R5_GAS_NOBLOCK;
5968 	sh = raid5_get_active_stripe(conf, ctx, new_sector, flags);
5969 	if (unlikely(!sh)) {
5970 		/* cannot get stripe, just give-up */
5971 		bi->bi_status = BLK_STS_IOERR;
5972 		return STRIPE_FAIL;
5973 	}
5974 
5975 	if (unlikely(previous) &&
5976 	    stripe_ahead_of_reshape(mddev, conf, sh)) {
5977 		/*
5978 		 * Expansion moved on while waiting for a stripe.
5979 		 * Expansion could still move past after this
5980 		 * test, but as we are holding a reference to
5981 		 * 'sh', we know that if that happens,
5982 		 *  STRIPE_EXPANDING will get set and the expansion
5983 		 * won't proceed until we finish with the stripe.
5984 		 */
5985 		ret = STRIPE_SCHEDULE_AND_RETRY;
5986 		goto out_release;
5987 	}
5988 
5989 	if (read_seqcount_retry(&conf->gen_lock, seq)) {
5990 		/* Might have got the wrong stripe_head by accident */
5991 		ret = STRIPE_RETRY;
5992 		goto out_release;
5993 	}
5994 
5995 	if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5996 	    !add_all_stripe_bios(conf, ctx, sh, bi, rw, previous)) {
5997 		/*
5998 		 * Stripe is busy expanding or add failed due to
5999 		 * overlap. Flush everything and wait a while.
6000 		 */
6001 		md_wakeup_thread(mddev->thread);
6002 		ret = STRIPE_SCHEDULE_AND_RETRY;
6003 		goto out_release;
6004 	}
6005 
6006 	if (stripe_can_batch(sh)) {
6007 		stripe_add_to_batch_list(conf, sh, ctx->batch_last);
6008 		if (ctx->batch_last)
6009 			raid5_release_stripe(ctx->batch_last);
6010 		atomic_inc(&sh->count);
6011 		ctx->batch_last = sh;
6012 	}
6013 
6014 	if (ctx->do_flush) {
6015 		set_bit(STRIPE_R5C_PREFLUSH, &sh->state);
6016 		/* we only need flush for one stripe */
6017 		ctx->do_flush = false;
6018 	}
6019 
6020 	set_bit(STRIPE_HANDLE, &sh->state);
6021 	clear_bit(STRIPE_DELAYED, &sh->state);
6022 	if ((!sh->batch_head || sh == sh->batch_head) &&
6023 	    (bi->bi_opf & REQ_SYNC) &&
6024 	    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
6025 		atomic_inc(&conf->preread_active_stripes);
6026 
6027 	release_stripe_plug(mddev, sh);
6028 	return STRIPE_SUCCESS;
6029 
6030 out_release:
6031 	raid5_release_stripe(sh);
6032 out:
6033 	if (ret == STRIPE_SCHEDULE_AND_RETRY && reshape_interrupted(mddev)) {
6034 		bi->bi_status = BLK_STS_RESOURCE;
6035 		ret = STRIPE_WAIT_RESHAPE;
6036 		pr_err_ratelimited("dm-raid456: io across reshape position while reshape can't make progress");
6037 	}
6038 	return ret;
6039 }
6040 
6041 /*
6042  * If the bio covers multiple data disks, find sector within the bio that has
6043  * the lowest chunk offset in the first chunk.
6044  */
6045 static sector_t raid5_bio_lowest_chunk_sector(struct r5conf *conf,
6046 					      struct bio *bi)
6047 {
6048 	int sectors_per_chunk = conf->chunk_sectors;
6049 	int raid_disks = conf->raid_disks;
6050 	int dd_idx;
6051 	struct stripe_head sh;
6052 	unsigned int chunk_offset;
6053 	sector_t r_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
6054 	sector_t sector;
6055 
6056 	/* We pass in fake stripe_head to get back parity disk numbers */
6057 	sector = raid5_compute_sector(conf, r_sector, 0, &dd_idx, &sh);
6058 	chunk_offset = sector_div(sector, sectors_per_chunk);
6059 	if (sectors_per_chunk - chunk_offset >= bio_sectors(bi))
6060 		return r_sector;
6061 	/*
6062 	 * Bio crosses to the next data disk. Check whether it's in the same
6063 	 * chunk.
6064 	 */
6065 	dd_idx++;
6066 	while (dd_idx == sh.pd_idx || dd_idx == sh.qd_idx)
6067 		dd_idx++;
6068 	if (dd_idx >= raid_disks)
6069 		return r_sector;
6070 	return r_sector + sectors_per_chunk - chunk_offset;
6071 }
6072 
6073 static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
6074 {
6075 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
6076 	struct r5conf *conf = mddev->private;
6077 	sector_t logical_sector;
6078 	struct stripe_request_ctx ctx = {};
6079 	const int rw = bio_data_dir(bi);
6080 	enum stripe_result res;
6081 	int s, stripe_cnt;
6082 
6083 	if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
6084 		int ret = log_handle_flush_request(conf, bi);
6085 
6086 		if (ret == 0)
6087 			return true;
6088 		if (ret == -ENODEV) {
6089 			if (md_flush_request(mddev, bi))
6090 				return true;
6091 		}
6092 		/* ret == -EAGAIN, fallback */
6093 		/*
6094 		 * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
6095 		 * we need to flush journal device
6096 		 */
6097 		ctx.do_flush = bi->bi_opf & REQ_PREFLUSH;
6098 	}
6099 
6100 	md_write_start(mddev, bi);
6101 	/*
6102 	 * If array is degraded, better not do chunk aligned read because
6103 	 * later we might have to read it again in order to reconstruct
6104 	 * data on failed drives.
6105 	 */
6106 	if (rw == READ && mddev->degraded == 0 &&
6107 	    mddev->reshape_position == MaxSector) {
6108 		bi = chunk_aligned_read(mddev, bi);
6109 		if (!bi)
6110 			return true;
6111 	}
6112 
6113 	if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) {
6114 		make_discard_request(mddev, bi);
6115 		md_write_end(mddev);
6116 		return true;
6117 	}
6118 
6119 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
6120 	ctx.first_sector = logical_sector;
6121 	ctx.last_sector = bio_end_sector(bi);
6122 	bi->bi_next = NULL;
6123 
6124 	stripe_cnt = DIV_ROUND_UP_SECTOR_T(ctx.last_sector - logical_sector,
6125 					   RAID5_STRIPE_SECTORS(conf));
6126 	bitmap_set(ctx.sectors_to_do, 0, stripe_cnt);
6127 
6128 	pr_debug("raid456: %s, logical %llu to %llu\n", __func__,
6129 		 bi->bi_iter.bi_sector, ctx.last_sector);
6130 
6131 	/* Bail out if conflicts with reshape and REQ_NOWAIT is set */
6132 	if ((bi->bi_opf & REQ_NOWAIT) &&
6133 	    (conf->reshape_progress != MaxSector) &&
6134 	    get_reshape_loc(mddev, conf, logical_sector) == LOC_INSIDE_RESHAPE) {
6135 		bio_wouldblock_error(bi);
6136 		if (rw == WRITE)
6137 			md_write_end(mddev);
6138 		return true;
6139 	}
6140 	md_account_bio(mddev, &bi);
6141 
6142 	/*
6143 	 * Lets start with the stripe with the lowest chunk offset in the first
6144 	 * chunk. That has the best chances of creating IOs adjacent to
6145 	 * previous IOs in case of sequential IO and thus creates the most
6146 	 * sequential IO pattern. We don't bother with the optimization when
6147 	 * reshaping as the performance benefit is not worth the complexity.
6148 	 */
6149 	if (likely(conf->reshape_progress == MaxSector))
6150 		logical_sector = raid5_bio_lowest_chunk_sector(conf, bi);
6151 	s = (logical_sector - ctx.first_sector) >> RAID5_STRIPE_SHIFT(conf);
6152 
6153 	add_wait_queue(&conf->wait_for_overlap, &wait);
6154 	while (1) {
6155 		res = make_stripe_request(mddev, conf, &ctx, logical_sector,
6156 					  bi);
6157 		if (res == STRIPE_FAIL || res == STRIPE_WAIT_RESHAPE)
6158 			break;
6159 
6160 		if (res == STRIPE_RETRY)
6161 			continue;
6162 
6163 		if (res == STRIPE_SCHEDULE_AND_RETRY) {
6164 			/*
6165 			 * Must release the reference to batch_last before
6166 			 * scheduling and waiting for work to be done,
6167 			 * otherwise the batch_last stripe head could prevent
6168 			 * raid5_activate_delayed() from making progress
6169 			 * and thus deadlocking.
6170 			 */
6171 			if (ctx.batch_last) {
6172 				raid5_release_stripe(ctx.batch_last);
6173 				ctx.batch_last = NULL;
6174 			}
6175 
6176 			wait_woken(&wait, TASK_UNINTERRUPTIBLE,
6177 				   MAX_SCHEDULE_TIMEOUT);
6178 			continue;
6179 		}
6180 
6181 		s = find_next_bit_wrap(ctx.sectors_to_do, stripe_cnt, s);
6182 		if (s == stripe_cnt)
6183 			break;
6184 
6185 		logical_sector = ctx.first_sector +
6186 			(s << RAID5_STRIPE_SHIFT(conf));
6187 	}
6188 	remove_wait_queue(&conf->wait_for_overlap, &wait);
6189 
6190 	if (ctx.batch_last)
6191 		raid5_release_stripe(ctx.batch_last);
6192 
6193 	if (rw == WRITE)
6194 		md_write_end(mddev);
6195 	if (res == STRIPE_WAIT_RESHAPE) {
6196 		md_free_cloned_bio(bi);
6197 		return false;
6198 	}
6199 
6200 	bio_endio(bi);
6201 	return true;
6202 }
6203 
6204 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
6205 
6206 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
6207 {
6208 	/* reshaping is quite different to recovery/resync so it is
6209 	 * handled quite separately ... here.
6210 	 *
6211 	 * On each call to sync_request, we gather one chunk worth of
6212 	 * destination stripes and flag them as expanding.
6213 	 * Then we find all the source stripes and request reads.
6214 	 * As the reads complete, handle_stripe will copy the data
6215 	 * into the destination stripe and release that stripe.
6216 	 */
6217 	struct r5conf *conf = mddev->private;
6218 	struct stripe_head *sh;
6219 	struct md_rdev *rdev;
6220 	sector_t first_sector, last_sector;
6221 	int raid_disks = conf->previous_raid_disks;
6222 	int data_disks = raid_disks - conf->max_degraded;
6223 	int new_data_disks = conf->raid_disks - conf->max_degraded;
6224 	int i;
6225 	int dd_idx;
6226 	sector_t writepos, readpos, safepos;
6227 	sector_t stripe_addr;
6228 	int reshape_sectors;
6229 	struct list_head stripes;
6230 	sector_t retn;
6231 
6232 	if (sector_nr == 0) {
6233 		/* If restarting in the middle, skip the initial sectors */
6234 		if (mddev->reshape_backwards &&
6235 		    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
6236 			sector_nr = raid5_size(mddev, 0, 0)
6237 				- conf->reshape_progress;
6238 		} else if (mddev->reshape_backwards &&
6239 			   conf->reshape_progress == MaxSector) {
6240 			/* shouldn't happen, but just in case, finish up.*/
6241 			sector_nr = MaxSector;
6242 		} else if (!mddev->reshape_backwards &&
6243 			   conf->reshape_progress > 0)
6244 			sector_nr = conf->reshape_progress;
6245 		sector_div(sector_nr, new_data_disks);
6246 		if (sector_nr) {
6247 			mddev->curr_resync_completed = sector_nr;
6248 			sysfs_notify_dirent_safe(mddev->sysfs_completed);
6249 			*skipped = 1;
6250 			retn = sector_nr;
6251 			goto finish;
6252 		}
6253 	}
6254 
6255 	/* We need to process a full chunk at a time.
6256 	 * If old and new chunk sizes differ, we need to process the
6257 	 * largest of these
6258 	 */
6259 
6260 	reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
6261 
6262 	/* We update the metadata at least every 10 seconds, or when
6263 	 * the data about to be copied would over-write the source of
6264 	 * the data at the front of the range.  i.e. one new_stripe
6265 	 * along from reshape_progress new_maps to after where
6266 	 * reshape_safe old_maps to
6267 	 */
6268 	writepos = conf->reshape_progress;
6269 	sector_div(writepos, new_data_disks);
6270 	readpos = conf->reshape_progress;
6271 	sector_div(readpos, data_disks);
6272 	safepos = conf->reshape_safe;
6273 	sector_div(safepos, data_disks);
6274 	if (mddev->reshape_backwards) {
6275 		if (WARN_ON(writepos < reshape_sectors))
6276 			return MaxSector;
6277 
6278 		writepos -= reshape_sectors;
6279 		readpos += reshape_sectors;
6280 		safepos += reshape_sectors;
6281 	} else {
6282 		writepos += reshape_sectors;
6283 		/* readpos and safepos are worst-case calculations.
6284 		 * A negative number is overly pessimistic, and causes
6285 		 * obvious problems for unsigned storage.  So clip to 0.
6286 		 */
6287 		readpos -= min_t(sector_t, reshape_sectors, readpos);
6288 		safepos -= min_t(sector_t, reshape_sectors, safepos);
6289 	}
6290 
6291 	/* Having calculated the 'writepos' possibly use it
6292 	 * to set 'stripe_addr' which is where we will write to.
6293 	 */
6294 	if (mddev->reshape_backwards) {
6295 		if (WARN_ON(conf->reshape_progress == 0))
6296 			return MaxSector;
6297 
6298 		stripe_addr = writepos;
6299 		if (WARN_ON((mddev->dev_sectors &
6300 		    ~((sector_t)reshape_sectors - 1)) -
6301 		    reshape_sectors - stripe_addr != sector_nr))
6302 			return MaxSector;
6303 	} else {
6304 		if (WARN_ON(writepos != sector_nr + reshape_sectors))
6305 			return MaxSector;
6306 
6307 		stripe_addr = sector_nr;
6308 	}
6309 
6310 	/* 'writepos' is the most advanced device address we might write.
6311 	 * 'readpos' is the least advanced device address we might read.
6312 	 * 'safepos' is the least address recorded in the metadata as having
6313 	 *     been reshaped.
6314 	 * If there is a min_offset_diff, these are adjusted either by
6315 	 * increasing the safepos/readpos if diff is negative, or
6316 	 * increasing writepos if diff is positive.
6317 	 * If 'readpos' is then behind 'writepos', there is no way that we can
6318 	 * ensure safety in the face of a crash - that must be done by userspace
6319 	 * making a backup of the data.  So in that case there is no particular
6320 	 * rush to update metadata.
6321 	 * Otherwise if 'safepos' is behind 'writepos', then we really need to
6322 	 * update the metadata to advance 'safepos' to match 'readpos' so that
6323 	 * we can be safe in the event of a crash.
6324 	 * So we insist on updating metadata if safepos is behind writepos and
6325 	 * readpos is beyond writepos.
6326 	 * In any case, update the metadata every 10 seconds.
6327 	 * Maybe that number should be configurable, but I'm not sure it is
6328 	 * worth it.... maybe it could be a multiple of safemode_delay???
6329 	 */
6330 	if (conf->min_offset_diff < 0) {
6331 		safepos += -conf->min_offset_diff;
6332 		readpos += -conf->min_offset_diff;
6333 	} else
6334 		writepos += conf->min_offset_diff;
6335 
6336 	if ((mddev->reshape_backwards
6337 	     ? (safepos > writepos && readpos < writepos)
6338 	     : (safepos < writepos && readpos > writepos)) ||
6339 	    time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
6340 		/* Cannot proceed until we've updated the superblock... */
6341 		wait_event(conf->wait_for_overlap,
6342 			   atomic_read(&conf->reshape_stripes)==0
6343 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
6344 		if (atomic_read(&conf->reshape_stripes) != 0)
6345 			return 0;
6346 		mddev->reshape_position = conf->reshape_progress;
6347 		mddev->curr_resync_completed = sector_nr;
6348 		if (!mddev->reshape_backwards)
6349 			/* Can update recovery_offset */
6350 			rdev_for_each(rdev, mddev)
6351 				if (rdev->raid_disk >= 0 &&
6352 				    !test_bit(Journal, &rdev->flags) &&
6353 				    !test_bit(In_sync, &rdev->flags) &&
6354 				    rdev->recovery_offset < sector_nr)
6355 					rdev->recovery_offset = sector_nr;
6356 
6357 		conf->reshape_checkpoint = jiffies;
6358 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
6359 		md_wakeup_thread(mddev->thread);
6360 		wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
6361 			   test_bit(MD_RECOVERY_INTR, &mddev->recovery));
6362 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
6363 			return 0;
6364 		spin_lock_irq(&conf->device_lock);
6365 		conf->reshape_safe = mddev->reshape_position;
6366 		spin_unlock_irq(&conf->device_lock);
6367 		wake_up(&conf->wait_for_overlap);
6368 		sysfs_notify_dirent_safe(mddev->sysfs_completed);
6369 	}
6370 
6371 	INIT_LIST_HEAD(&stripes);
6372 	for (i = 0; i < reshape_sectors; i += RAID5_STRIPE_SECTORS(conf)) {
6373 		int j;
6374 		int skipped_disk = 0;
6375 		sh = raid5_get_active_stripe(conf, NULL, stripe_addr+i,
6376 					     R5_GAS_NOQUIESCE);
6377 		set_bit(STRIPE_EXPANDING, &sh->state);
6378 		atomic_inc(&conf->reshape_stripes);
6379 		/* If any of this stripe is beyond the end of the old
6380 		 * array, then we need to zero those blocks
6381 		 */
6382 		for (j=sh->disks; j--;) {
6383 			sector_t s;
6384 			if (j == sh->pd_idx)
6385 				continue;
6386 			if (conf->level == 6 &&
6387 			    j == sh->qd_idx)
6388 				continue;
6389 			s = raid5_compute_blocknr(sh, j, 0);
6390 			if (s < raid5_size(mddev, 0, 0)) {
6391 				skipped_disk = 1;
6392 				continue;
6393 			}
6394 			memset(page_address(sh->dev[j].page), 0, RAID5_STRIPE_SIZE(conf));
6395 			set_bit(R5_Expanded, &sh->dev[j].flags);
6396 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
6397 		}
6398 		if (!skipped_disk) {
6399 			set_bit(STRIPE_EXPAND_READY, &sh->state);
6400 			set_bit(STRIPE_HANDLE, &sh->state);
6401 		}
6402 		list_add(&sh->lru, &stripes);
6403 	}
6404 	spin_lock_irq(&conf->device_lock);
6405 	if (mddev->reshape_backwards)
6406 		conf->reshape_progress -= reshape_sectors * new_data_disks;
6407 	else
6408 		conf->reshape_progress += reshape_sectors * new_data_disks;
6409 	spin_unlock_irq(&conf->device_lock);
6410 	/* Ok, those stripe are ready. We can start scheduling
6411 	 * reads on the source stripes.
6412 	 * The source stripes are determined by mapping the first and last
6413 	 * block on the destination stripes.
6414 	 */
6415 	first_sector =
6416 		raid5_compute_sector(conf, stripe_addr*(new_data_disks),
6417 				     1, &dd_idx, NULL);
6418 	last_sector =
6419 		raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
6420 					    * new_data_disks - 1),
6421 				     1, &dd_idx, NULL);
6422 	if (last_sector >= mddev->dev_sectors)
6423 		last_sector = mddev->dev_sectors - 1;
6424 	while (first_sector <= last_sector) {
6425 		sh = raid5_get_active_stripe(conf, NULL, first_sector,
6426 				R5_GAS_PREVIOUS | R5_GAS_NOQUIESCE);
6427 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
6428 		set_bit(STRIPE_HANDLE, &sh->state);
6429 		raid5_release_stripe(sh);
6430 		first_sector += RAID5_STRIPE_SECTORS(conf);
6431 	}
6432 	/* Now that the sources are clearly marked, we can release
6433 	 * the destination stripes
6434 	 */
6435 	while (!list_empty(&stripes)) {
6436 		sh = list_entry(stripes.next, struct stripe_head, lru);
6437 		list_del_init(&sh->lru);
6438 		raid5_release_stripe(sh);
6439 	}
6440 	/* If this takes us to the resync_max point where we have to pause,
6441 	 * then we need to write out the superblock.
6442 	 */
6443 	sector_nr += reshape_sectors;
6444 	retn = reshape_sectors;
6445 finish:
6446 	if (mddev->curr_resync_completed > mddev->resync_max ||
6447 	    (sector_nr - mddev->curr_resync_completed) * 2
6448 	    >= mddev->resync_max - mddev->curr_resync_completed) {
6449 		/* Cannot proceed until we've updated the superblock... */
6450 		wait_event(conf->wait_for_overlap,
6451 			   atomic_read(&conf->reshape_stripes) == 0
6452 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
6453 		if (atomic_read(&conf->reshape_stripes) != 0)
6454 			goto ret;
6455 		mddev->reshape_position = conf->reshape_progress;
6456 		mddev->curr_resync_completed = sector_nr;
6457 		if (!mddev->reshape_backwards)
6458 			/* Can update recovery_offset */
6459 			rdev_for_each(rdev, mddev)
6460 				if (rdev->raid_disk >= 0 &&
6461 				    !test_bit(Journal, &rdev->flags) &&
6462 				    !test_bit(In_sync, &rdev->flags) &&
6463 				    rdev->recovery_offset < sector_nr)
6464 					rdev->recovery_offset = sector_nr;
6465 		conf->reshape_checkpoint = jiffies;
6466 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
6467 		md_wakeup_thread(mddev->thread);
6468 		wait_event(mddev->sb_wait,
6469 			   !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)
6470 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
6471 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
6472 			goto ret;
6473 		spin_lock_irq(&conf->device_lock);
6474 		conf->reshape_safe = mddev->reshape_position;
6475 		spin_unlock_irq(&conf->device_lock);
6476 		wake_up(&conf->wait_for_overlap);
6477 		sysfs_notify_dirent_safe(mddev->sysfs_completed);
6478 	}
6479 ret:
6480 	return retn;
6481 }
6482 
6483 static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_nr,
6484 					  sector_t max_sector, int *skipped)
6485 {
6486 	struct r5conf *conf = mddev->private;
6487 	struct stripe_head *sh;
6488 	sector_t sync_blocks;
6489 	int still_degraded = 0;
6490 	int i;
6491 
6492 	if (sector_nr >= max_sector) {
6493 		/* just being told to finish up .. nothing much to do */
6494 
6495 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
6496 			end_reshape(conf);
6497 			return 0;
6498 		}
6499 
6500 		if (mddev->curr_resync < max_sector) /* aborted */
6501 			md_bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
6502 					   &sync_blocks, 1);
6503 		else /* completed sync */
6504 			conf->fullsync = 0;
6505 		md_bitmap_close_sync(mddev->bitmap);
6506 
6507 		return 0;
6508 	}
6509 
6510 	/* Allow raid5_quiesce to complete */
6511 	wait_event(conf->wait_for_overlap, conf->quiesce != 2);
6512 
6513 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
6514 		return reshape_request(mddev, sector_nr, skipped);
6515 
6516 	/* No need to check resync_max as we never do more than one
6517 	 * stripe, and as resync_max will always be on a chunk boundary,
6518 	 * if the check in md_do_sync didn't fire, there is no chance
6519 	 * of overstepping resync_max here
6520 	 */
6521 
6522 	/* if there is too many failed drives and we are trying
6523 	 * to resync, then assert that we are finished, because there is
6524 	 * nothing we can do.
6525 	 */
6526 	if (mddev->degraded >= conf->max_degraded &&
6527 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
6528 		sector_t rv = mddev->dev_sectors - sector_nr;
6529 		*skipped = 1;
6530 		return rv;
6531 	}
6532 	if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
6533 	    !conf->fullsync &&
6534 	    !md_bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
6535 	    sync_blocks >= RAID5_STRIPE_SECTORS(conf)) {
6536 		/* we can skip this block, and probably more */
6537 		do_div(sync_blocks, RAID5_STRIPE_SECTORS(conf));
6538 		*skipped = 1;
6539 		/* keep things rounded to whole stripes */
6540 		return sync_blocks * RAID5_STRIPE_SECTORS(conf);
6541 	}
6542 
6543 	md_bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
6544 
6545 	sh = raid5_get_active_stripe(conf, NULL, sector_nr,
6546 				     R5_GAS_NOBLOCK);
6547 	if (sh == NULL) {
6548 		sh = raid5_get_active_stripe(conf, NULL, sector_nr, 0);
6549 		/* make sure we don't swamp the stripe cache if someone else
6550 		 * is trying to get access
6551 		 */
6552 		schedule_timeout_uninterruptible(1);
6553 	}
6554 	/* Need to check if array will still be degraded after recovery/resync
6555 	 * Note in case of > 1 drive failures it's possible we're rebuilding
6556 	 * one drive while leaving another faulty drive in array.
6557 	 */
6558 	for (i = 0; i < conf->raid_disks; i++) {
6559 		struct md_rdev *rdev = conf->disks[i].rdev;
6560 
6561 		if (rdev == NULL || test_bit(Faulty, &rdev->flags))
6562 			still_degraded = 1;
6563 	}
6564 
6565 	md_bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
6566 
6567 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
6568 	set_bit(STRIPE_HANDLE, &sh->state);
6569 
6570 	raid5_release_stripe(sh);
6571 
6572 	return RAID5_STRIPE_SECTORS(conf);
6573 }
6574 
6575 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio,
6576 			       unsigned int offset)
6577 {
6578 	/* We may not be able to submit a whole bio at once as there
6579 	 * may not be enough stripe_heads available.
6580 	 * We cannot pre-allocate enough stripe_heads as we may need
6581 	 * more than exist in the cache (if we allow ever large chunks).
6582 	 * So we do one stripe head at a time and record in
6583 	 * ->bi_hw_segments how many have been done.
6584 	 *
6585 	 * We *know* that this entire raid_bio is in one chunk, so
6586 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
6587 	 */
6588 	struct stripe_head *sh;
6589 	int dd_idx;
6590 	sector_t sector, logical_sector, last_sector;
6591 	int scnt = 0;
6592 	int handled = 0;
6593 
6594 	logical_sector = raid_bio->bi_iter.bi_sector &
6595 		~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
6596 	sector = raid5_compute_sector(conf, logical_sector,
6597 				      0, &dd_idx, NULL);
6598 	last_sector = bio_end_sector(raid_bio);
6599 
6600 	for (; logical_sector < last_sector;
6601 	     logical_sector += RAID5_STRIPE_SECTORS(conf),
6602 		     sector += RAID5_STRIPE_SECTORS(conf),
6603 		     scnt++) {
6604 
6605 		if (scnt < offset)
6606 			/* already done this stripe */
6607 			continue;
6608 
6609 		sh = raid5_get_active_stripe(conf, NULL, sector,
6610 				R5_GAS_NOBLOCK | R5_GAS_NOQUIESCE);
6611 		if (!sh) {
6612 			/* failed to get a stripe - must wait */
6613 			conf->retry_read_aligned = raid_bio;
6614 			conf->retry_read_offset = scnt;
6615 			return handled;
6616 		}
6617 
6618 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
6619 			raid5_release_stripe(sh);
6620 			conf->retry_read_aligned = raid_bio;
6621 			conf->retry_read_offset = scnt;
6622 			return handled;
6623 		}
6624 
6625 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
6626 		handle_stripe(sh);
6627 		raid5_release_stripe(sh);
6628 		handled++;
6629 	}
6630 
6631 	bio_endio(raid_bio);
6632 
6633 	if (atomic_dec_and_test(&conf->active_aligned_reads))
6634 		wake_up(&conf->wait_for_quiescent);
6635 	return handled;
6636 }
6637 
6638 static int handle_active_stripes(struct r5conf *conf, int group,
6639 				 struct r5worker *worker,
6640 				 struct list_head *temp_inactive_list)
6641 		__must_hold(&conf->device_lock)
6642 {
6643 	struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
6644 	int i, batch_size = 0, hash;
6645 	bool release_inactive = false;
6646 
6647 	while (batch_size < MAX_STRIPE_BATCH &&
6648 			(sh = __get_priority_stripe(conf, group)) != NULL)
6649 		batch[batch_size++] = sh;
6650 
6651 	if (batch_size == 0) {
6652 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6653 			if (!list_empty(temp_inactive_list + i))
6654 				break;
6655 		if (i == NR_STRIPE_HASH_LOCKS) {
6656 			spin_unlock_irq(&conf->device_lock);
6657 			log_flush_stripe_to_raid(conf);
6658 			spin_lock_irq(&conf->device_lock);
6659 			return batch_size;
6660 		}
6661 		release_inactive = true;
6662 	}
6663 	spin_unlock_irq(&conf->device_lock);
6664 
6665 	release_inactive_stripe_list(conf, temp_inactive_list,
6666 				     NR_STRIPE_HASH_LOCKS);
6667 
6668 	r5l_flush_stripe_to_raid(conf->log);
6669 	if (release_inactive) {
6670 		spin_lock_irq(&conf->device_lock);
6671 		return 0;
6672 	}
6673 
6674 	for (i = 0; i < batch_size; i++)
6675 		handle_stripe(batch[i]);
6676 	log_write_stripe_run(conf);
6677 
6678 	cond_resched();
6679 
6680 	spin_lock_irq(&conf->device_lock);
6681 	for (i = 0; i < batch_size; i++) {
6682 		hash = batch[i]->hash_lock_index;
6683 		__release_stripe(conf, batch[i], &temp_inactive_list[hash]);
6684 	}
6685 	return batch_size;
6686 }
6687 
6688 static void raid5_do_work(struct work_struct *work)
6689 {
6690 	struct r5worker *worker = container_of(work, struct r5worker, work);
6691 	struct r5worker_group *group = worker->group;
6692 	struct r5conf *conf = group->conf;
6693 	struct mddev *mddev = conf->mddev;
6694 	int group_id = group - conf->worker_groups;
6695 	int handled;
6696 	struct blk_plug plug;
6697 
6698 	pr_debug("+++ raid5worker active\n");
6699 
6700 	blk_start_plug(&plug);
6701 	handled = 0;
6702 	spin_lock_irq(&conf->device_lock);
6703 	while (1) {
6704 		int batch_size, released;
6705 
6706 		released = release_stripe_list(conf, worker->temp_inactive_list);
6707 
6708 		batch_size = handle_active_stripes(conf, group_id, worker,
6709 						   worker->temp_inactive_list);
6710 		worker->working = false;
6711 		if (!batch_size && !released)
6712 			break;
6713 		handled += batch_size;
6714 		wait_event_lock_irq(mddev->sb_wait,
6715 			!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags),
6716 			conf->device_lock);
6717 	}
6718 	pr_debug("%d stripes handled\n", handled);
6719 
6720 	spin_unlock_irq(&conf->device_lock);
6721 
6722 	flush_deferred_bios(conf);
6723 
6724 	r5l_flush_stripe_to_raid(conf->log);
6725 
6726 	async_tx_issue_pending_all();
6727 	blk_finish_plug(&plug);
6728 
6729 	pr_debug("--- raid5worker inactive\n");
6730 }
6731 
6732 /*
6733  * This is our raid5 kernel thread.
6734  *
6735  * We scan the hash table for stripes which can be handled now.
6736  * During the scan, completed stripes are saved for us by the interrupt
6737  * handler, so that they will not have to wait for our next wakeup.
6738  */
6739 static void raid5d(struct md_thread *thread)
6740 {
6741 	struct mddev *mddev = thread->mddev;
6742 	struct r5conf *conf = mddev->private;
6743 	int handled;
6744 	struct blk_plug plug;
6745 
6746 	pr_debug("+++ raid5d active\n");
6747 
6748 	md_check_recovery(mddev);
6749 
6750 	blk_start_plug(&plug);
6751 	handled = 0;
6752 	spin_lock_irq(&conf->device_lock);
6753 	while (1) {
6754 		struct bio *bio;
6755 		int batch_size, released;
6756 		unsigned int offset;
6757 
6758 		if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
6759 			break;
6760 
6761 		released = release_stripe_list(conf, conf->temp_inactive_list);
6762 		if (released)
6763 			clear_bit(R5_DID_ALLOC, &conf->cache_state);
6764 
6765 		if (
6766 		    !list_empty(&conf->bitmap_list)) {
6767 			/* Now is a good time to flush some bitmap updates */
6768 			conf->seq_flush++;
6769 			spin_unlock_irq(&conf->device_lock);
6770 			md_bitmap_unplug(mddev->bitmap);
6771 			spin_lock_irq(&conf->device_lock);
6772 			conf->seq_write = conf->seq_flush;
6773 			activate_bit_delay(conf, conf->temp_inactive_list);
6774 		}
6775 		raid5_activate_delayed(conf);
6776 
6777 		while ((bio = remove_bio_from_retry(conf, &offset))) {
6778 			int ok;
6779 			spin_unlock_irq(&conf->device_lock);
6780 			ok = retry_aligned_read(conf, bio, offset);
6781 			spin_lock_irq(&conf->device_lock);
6782 			if (!ok)
6783 				break;
6784 			handled++;
6785 		}
6786 
6787 		batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
6788 						   conf->temp_inactive_list);
6789 		if (!batch_size && !released)
6790 			break;
6791 		handled += batch_size;
6792 
6793 		if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
6794 			spin_unlock_irq(&conf->device_lock);
6795 			md_check_recovery(mddev);
6796 			spin_lock_irq(&conf->device_lock);
6797 		}
6798 	}
6799 	pr_debug("%d stripes handled\n", handled);
6800 
6801 	spin_unlock_irq(&conf->device_lock);
6802 	if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
6803 	    mutex_trylock(&conf->cache_size_mutex)) {
6804 		grow_one_stripe(conf, __GFP_NOWARN);
6805 		/* Set flag even if allocation failed.  This helps
6806 		 * slow down allocation requests when mem is short
6807 		 */
6808 		set_bit(R5_DID_ALLOC, &conf->cache_state);
6809 		mutex_unlock(&conf->cache_size_mutex);
6810 	}
6811 
6812 	flush_deferred_bios(conf);
6813 
6814 	r5l_flush_stripe_to_raid(conf->log);
6815 
6816 	async_tx_issue_pending_all();
6817 	blk_finish_plug(&plug);
6818 
6819 	pr_debug("--- raid5d inactive\n");
6820 }
6821 
6822 static ssize_t
6823 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
6824 {
6825 	struct r5conf *conf;
6826 	int ret = 0;
6827 	spin_lock(&mddev->lock);
6828 	conf = mddev->private;
6829 	if (conf)
6830 		ret = sprintf(page, "%d\n", conf->min_nr_stripes);
6831 	spin_unlock(&mddev->lock);
6832 	return ret;
6833 }
6834 
6835 int
6836 raid5_set_cache_size(struct mddev *mddev, int size)
6837 {
6838 	int result = 0;
6839 	struct r5conf *conf = mddev->private;
6840 
6841 	if (size <= 16 || size > 32768)
6842 		return -EINVAL;
6843 
6844 	WRITE_ONCE(conf->min_nr_stripes, size);
6845 	mutex_lock(&conf->cache_size_mutex);
6846 	while (size < conf->max_nr_stripes &&
6847 	       drop_one_stripe(conf))
6848 		;
6849 	mutex_unlock(&conf->cache_size_mutex);
6850 
6851 	md_allow_write(mddev);
6852 
6853 	mutex_lock(&conf->cache_size_mutex);
6854 	while (size > conf->max_nr_stripes)
6855 		if (!grow_one_stripe(conf, GFP_KERNEL)) {
6856 			WRITE_ONCE(conf->min_nr_stripes, conf->max_nr_stripes);
6857 			result = -ENOMEM;
6858 			break;
6859 		}
6860 	mutex_unlock(&conf->cache_size_mutex);
6861 
6862 	return result;
6863 }
6864 EXPORT_SYMBOL(raid5_set_cache_size);
6865 
6866 static ssize_t
6867 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6868 {
6869 	struct r5conf *conf;
6870 	unsigned long new;
6871 	int err;
6872 
6873 	if (len >= PAGE_SIZE)
6874 		return -EINVAL;
6875 	if (kstrtoul(page, 10, &new))
6876 		return -EINVAL;
6877 	err = mddev_lock(mddev);
6878 	if (err)
6879 		return err;
6880 	conf = mddev->private;
6881 	if (!conf)
6882 		err = -ENODEV;
6883 	else
6884 		err = raid5_set_cache_size(mddev, new);
6885 	mddev_unlock(mddev);
6886 
6887 	return err ?: len;
6888 }
6889 
6890 static struct md_sysfs_entry
6891 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6892 				raid5_show_stripe_cache_size,
6893 				raid5_store_stripe_cache_size);
6894 
6895 static ssize_t
6896 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6897 {
6898 	struct r5conf *conf = mddev->private;
6899 	if (conf)
6900 		return sprintf(page, "%d\n", conf->rmw_level);
6901 	else
6902 		return 0;
6903 }
6904 
6905 static ssize_t
6906 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6907 {
6908 	struct r5conf *conf = mddev->private;
6909 	unsigned long new;
6910 
6911 	if (!conf)
6912 		return -ENODEV;
6913 
6914 	if (len >= PAGE_SIZE)
6915 		return -EINVAL;
6916 
6917 	if (kstrtoul(page, 10, &new))
6918 		return -EINVAL;
6919 
6920 	if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6921 		return -EINVAL;
6922 
6923 	if (new != PARITY_DISABLE_RMW &&
6924 	    new != PARITY_ENABLE_RMW &&
6925 	    new != PARITY_PREFER_RMW)
6926 		return -EINVAL;
6927 
6928 	conf->rmw_level = new;
6929 	return len;
6930 }
6931 
6932 static struct md_sysfs_entry
6933 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
6934 			 raid5_show_rmw_level,
6935 			 raid5_store_rmw_level);
6936 
6937 static ssize_t
6938 raid5_show_stripe_size(struct mddev  *mddev, char *page)
6939 {
6940 	struct r5conf *conf;
6941 	int ret = 0;
6942 
6943 	spin_lock(&mddev->lock);
6944 	conf = mddev->private;
6945 	if (conf)
6946 		ret = sprintf(page, "%lu\n", RAID5_STRIPE_SIZE(conf));
6947 	spin_unlock(&mddev->lock);
6948 	return ret;
6949 }
6950 
6951 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
6952 static ssize_t
6953 raid5_store_stripe_size(struct mddev  *mddev, const char *page, size_t len)
6954 {
6955 	struct r5conf *conf;
6956 	unsigned long new;
6957 	int err;
6958 	int size;
6959 
6960 	if (len >= PAGE_SIZE)
6961 		return -EINVAL;
6962 	if (kstrtoul(page, 10, &new))
6963 		return -EINVAL;
6964 
6965 	/*
6966 	 * The value should not be bigger than PAGE_SIZE. It requires to
6967 	 * be multiple of DEFAULT_STRIPE_SIZE and the value should be power
6968 	 * of two.
6969 	 */
6970 	if (new % DEFAULT_STRIPE_SIZE != 0 ||
6971 			new > PAGE_SIZE || new == 0 ||
6972 			new != roundup_pow_of_two(new))
6973 		return -EINVAL;
6974 
6975 	err = mddev_suspend_and_lock(mddev);
6976 	if (err)
6977 		return err;
6978 
6979 	conf = mddev->private;
6980 	if (!conf) {
6981 		err = -ENODEV;
6982 		goto out_unlock;
6983 	}
6984 
6985 	if (new == conf->stripe_size)
6986 		goto out_unlock;
6987 
6988 	pr_debug("md/raid: change stripe_size from %lu to %lu\n",
6989 			conf->stripe_size, new);
6990 
6991 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
6992 	    mddev->reshape_position != MaxSector || mddev->sysfs_active) {
6993 		err = -EBUSY;
6994 		goto out_unlock;
6995 	}
6996 
6997 	mutex_lock(&conf->cache_size_mutex);
6998 	size = conf->max_nr_stripes;
6999 
7000 	shrink_stripes(conf);
7001 
7002 	conf->stripe_size = new;
7003 	conf->stripe_shift = ilog2(new) - 9;
7004 	conf->stripe_sectors = new >> 9;
7005 	if (grow_stripes(conf, size)) {
7006 		pr_warn("md/raid:%s: couldn't allocate buffers\n",
7007 				mdname(mddev));
7008 		err = -ENOMEM;
7009 	}
7010 	mutex_unlock(&conf->cache_size_mutex);
7011 
7012 out_unlock:
7013 	mddev_unlock_and_resume(mddev);
7014 	return err ?: len;
7015 }
7016 
7017 static struct md_sysfs_entry
7018 raid5_stripe_size = __ATTR(stripe_size, 0644,
7019 			 raid5_show_stripe_size,
7020 			 raid5_store_stripe_size);
7021 #else
7022 static struct md_sysfs_entry
7023 raid5_stripe_size = __ATTR(stripe_size, 0444,
7024 			 raid5_show_stripe_size,
7025 			 NULL);
7026 #endif
7027 
7028 static ssize_t
7029 raid5_show_preread_threshold(struct mddev *mddev, char *page)
7030 {
7031 	struct r5conf *conf;
7032 	int ret = 0;
7033 	spin_lock(&mddev->lock);
7034 	conf = mddev->private;
7035 	if (conf)
7036 		ret = sprintf(page, "%d\n", conf->bypass_threshold);
7037 	spin_unlock(&mddev->lock);
7038 	return ret;
7039 }
7040 
7041 static ssize_t
7042 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
7043 {
7044 	struct r5conf *conf;
7045 	unsigned long new;
7046 	int err;
7047 
7048 	if (len >= PAGE_SIZE)
7049 		return -EINVAL;
7050 	if (kstrtoul(page, 10, &new))
7051 		return -EINVAL;
7052 
7053 	err = mddev_lock(mddev);
7054 	if (err)
7055 		return err;
7056 	conf = mddev->private;
7057 	if (!conf)
7058 		err = -ENODEV;
7059 	else if (new > conf->min_nr_stripes)
7060 		err = -EINVAL;
7061 	else
7062 		conf->bypass_threshold = new;
7063 	mddev_unlock(mddev);
7064 	return err ?: len;
7065 }
7066 
7067 static struct md_sysfs_entry
7068 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
7069 					S_IRUGO | S_IWUSR,
7070 					raid5_show_preread_threshold,
7071 					raid5_store_preread_threshold);
7072 
7073 static ssize_t
7074 raid5_show_skip_copy(struct mddev *mddev, char *page)
7075 {
7076 	struct r5conf *conf;
7077 	int ret = 0;
7078 	spin_lock(&mddev->lock);
7079 	conf = mddev->private;
7080 	if (conf)
7081 		ret = sprintf(page, "%d\n", conf->skip_copy);
7082 	spin_unlock(&mddev->lock);
7083 	return ret;
7084 }
7085 
7086 static ssize_t
7087 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
7088 {
7089 	struct r5conf *conf;
7090 	unsigned long new;
7091 	int err;
7092 
7093 	if (len >= PAGE_SIZE)
7094 		return -EINVAL;
7095 	if (kstrtoul(page, 10, &new))
7096 		return -EINVAL;
7097 	new = !!new;
7098 
7099 	err = mddev_suspend_and_lock(mddev);
7100 	if (err)
7101 		return err;
7102 	conf = mddev->private;
7103 	if (!conf)
7104 		err = -ENODEV;
7105 	else if (new != conf->skip_copy) {
7106 		struct request_queue *q = mddev->gendisk->queue;
7107 		struct queue_limits lim = queue_limits_start_update(q);
7108 
7109 		conf->skip_copy = new;
7110 		if (new)
7111 			lim.features |= BLK_FEAT_STABLE_WRITES;
7112 		else
7113 			lim.features &= ~BLK_FEAT_STABLE_WRITES;
7114 		err = queue_limits_commit_update(q, &lim);
7115 	}
7116 	mddev_unlock_and_resume(mddev);
7117 	return err ?: len;
7118 }
7119 
7120 static struct md_sysfs_entry
7121 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
7122 					raid5_show_skip_copy,
7123 					raid5_store_skip_copy);
7124 
7125 static ssize_t
7126 stripe_cache_active_show(struct mddev *mddev, char *page)
7127 {
7128 	struct r5conf *conf = mddev->private;
7129 	if (conf)
7130 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
7131 	else
7132 		return 0;
7133 }
7134 
7135 static struct md_sysfs_entry
7136 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
7137 
7138 static ssize_t
7139 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
7140 {
7141 	struct r5conf *conf;
7142 	int ret = 0;
7143 	spin_lock(&mddev->lock);
7144 	conf = mddev->private;
7145 	if (conf)
7146 		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
7147 	spin_unlock(&mddev->lock);
7148 	return ret;
7149 }
7150 
7151 static int alloc_thread_groups(struct r5conf *conf, int cnt,
7152 			       int *group_cnt,
7153 			       struct r5worker_group **worker_groups);
7154 static ssize_t
7155 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
7156 {
7157 	struct r5conf *conf;
7158 	unsigned int new;
7159 	int err;
7160 	struct r5worker_group *new_groups, *old_groups;
7161 	int group_cnt;
7162 
7163 	if (len >= PAGE_SIZE)
7164 		return -EINVAL;
7165 	if (kstrtouint(page, 10, &new))
7166 		return -EINVAL;
7167 	/* 8192 should be big enough */
7168 	if (new > 8192)
7169 		return -EINVAL;
7170 
7171 	err = mddev_suspend_and_lock(mddev);
7172 	if (err)
7173 		return err;
7174 	conf = mddev->private;
7175 	if (!conf)
7176 		err = -ENODEV;
7177 	else if (new != conf->worker_cnt_per_group) {
7178 		old_groups = conf->worker_groups;
7179 		if (old_groups)
7180 			flush_workqueue(raid5_wq);
7181 
7182 		err = alloc_thread_groups(conf, new, &group_cnt, &new_groups);
7183 		if (!err) {
7184 			spin_lock_irq(&conf->device_lock);
7185 			conf->group_cnt = group_cnt;
7186 			conf->worker_cnt_per_group = new;
7187 			conf->worker_groups = new_groups;
7188 			spin_unlock_irq(&conf->device_lock);
7189 
7190 			if (old_groups)
7191 				kfree(old_groups[0].workers);
7192 			kfree(old_groups);
7193 		}
7194 	}
7195 	mddev_unlock_and_resume(mddev);
7196 
7197 	return err ?: len;
7198 }
7199 
7200 static struct md_sysfs_entry
7201 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
7202 				raid5_show_group_thread_cnt,
7203 				raid5_store_group_thread_cnt);
7204 
7205 static struct attribute *raid5_attrs[] =  {
7206 	&raid5_stripecache_size.attr,
7207 	&raid5_stripecache_active.attr,
7208 	&raid5_preread_bypass_threshold.attr,
7209 	&raid5_group_thread_cnt.attr,
7210 	&raid5_skip_copy.attr,
7211 	&raid5_rmw_level.attr,
7212 	&raid5_stripe_size.attr,
7213 	&r5c_journal_mode.attr,
7214 	&ppl_write_hint.attr,
7215 	NULL,
7216 };
7217 static const struct attribute_group raid5_attrs_group = {
7218 	.name = NULL,
7219 	.attrs = raid5_attrs,
7220 };
7221 
7222 static int alloc_thread_groups(struct r5conf *conf, int cnt, int *group_cnt,
7223 			       struct r5worker_group **worker_groups)
7224 {
7225 	int i, j, k;
7226 	ssize_t size;
7227 	struct r5worker *workers;
7228 
7229 	if (cnt == 0) {
7230 		*group_cnt = 0;
7231 		*worker_groups = NULL;
7232 		return 0;
7233 	}
7234 	*group_cnt = num_possible_nodes();
7235 	size = sizeof(struct r5worker) * cnt;
7236 	workers = kcalloc(size, *group_cnt, GFP_NOIO);
7237 	*worker_groups = kcalloc(*group_cnt, sizeof(struct r5worker_group),
7238 				 GFP_NOIO);
7239 	if (!*worker_groups || !workers) {
7240 		kfree(workers);
7241 		kfree(*worker_groups);
7242 		return -ENOMEM;
7243 	}
7244 
7245 	for (i = 0; i < *group_cnt; i++) {
7246 		struct r5worker_group *group;
7247 
7248 		group = &(*worker_groups)[i];
7249 		INIT_LIST_HEAD(&group->handle_list);
7250 		INIT_LIST_HEAD(&group->loprio_list);
7251 		group->conf = conf;
7252 		group->workers = workers + i * cnt;
7253 
7254 		for (j = 0; j < cnt; j++) {
7255 			struct r5worker *worker = group->workers + j;
7256 			worker->group = group;
7257 			INIT_WORK(&worker->work, raid5_do_work);
7258 
7259 			for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
7260 				INIT_LIST_HEAD(worker->temp_inactive_list + k);
7261 		}
7262 	}
7263 
7264 	return 0;
7265 }
7266 
7267 static void free_thread_groups(struct r5conf *conf)
7268 {
7269 	if (conf->worker_groups)
7270 		kfree(conf->worker_groups[0].workers);
7271 	kfree(conf->worker_groups);
7272 	conf->worker_groups = NULL;
7273 }
7274 
7275 static sector_t
7276 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
7277 {
7278 	struct r5conf *conf = mddev->private;
7279 
7280 	if (!sectors)
7281 		sectors = mddev->dev_sectors;
7282 	if (!raid_disks)
7283 		/* size is defined by the smallest of previous and new size */
7284 		raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
7285 
7286 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
7287 	sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
7288 	return sectors * (raid_disks - conf->max_degraded);
7289 }
7290 
7291 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
7292 {
7293 	safe_put_page(percpu->spare_page);
7294 	percpu->spare_page = NULL;
7295 	kvfree(percpu->scribble);
7296 	percpu->scribble = NULL;
7297 }
7298 
7299 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
7300 {
7301 	if (conf->level == 6 && !percpu->spare_page) {
7302 		percpu->spare_page = alloc_page(GFP_KERNEL);
7303 		if (!percpu->spare_page)
7304 			return -ENOMEM;
7305 	}
7306 
7307 	if (scribble_alloc(percpu,
7308 			   max(conf->raid_disks,
7309 			       conf->previous_raid_disks),
7310 			   max(conf->chunk_sectors,
7311 			       conf->prev_chunk_sectors)
7312 			   / RAID5_STRIPE_SECTORS(conf))) {
7313 		free_scratch_buffer(conf, percpu);
7314 		return -ENOMEM;
7315 	}
7316 
7317 	local_lock_init(&percpu->lock);
7318 	return 0;
7319 }
7320 
7321 static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
7322 {
7323 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
7324 
7325 	free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
7326 	return 0;
7327 }
7328 
7329 static void raid5_free_percpu(struct r5conf *conf)
7330 {
7331 	if (!conf->percpu)
7332 		return;
7333 
7334 	cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
7335 	free_percpu(conf->percpu);
7336 }
7337 
7338 static void free_conf(struct r5conf *conf)
7339 {
7340 	int i;
7341 
7342 	log_exit(conf);
7343 
7344 	shrinker_free(conf->shrinker);
7345 	free_thread_groups(conf);
7346 	shrink_stripes(conf);
7347 	raid5_free_percpu(conf);
7348 	for (i = 0; i < conf->pool_size; i++)
7349 		if (conf->disks[i].extra_page)
7350 			put_page(conf->disks[i].extra_page);
7351 	kfree(conf->disks);
7352 	bioset_exit(&conf->bio_split);
7353 	kfree(conf->stripe_hashtbl);
7354 	kfree(conf->pending_data);
7355 	kfree(conf);
7356 }
7357 
7358 static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
7359 {
7360 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
7361 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
7362 
7363 	if (alloc_scratch_buffer(conf, percpu)) {
7364 		pr_warn("%s: failed memory allocation for cpu%u\n",
7365 			__func__, cpu);
7366 		return -ENOMEM;
7367 	}
7368 	return 0;
7369 }
7370 
7371 static int raid5_alloc_percpu(struct r5conf *conf)
7372 {
7373 	int err = 0;
7374 
7375 	conf->percpu = alloc_percpu(struct raid5_percpu);
7376 	if (!conf->percpu)
7377 		return -ENOMEM;
7378 
7379 	err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
7380 	if (!err) {
7381 		conf->scribble_disks = max(conf->raid_disks,
7382 			conf->previous_raid_disks);
7383 		conf->scribble_sectors = max(conf->chunk_sectors,
7384 			conf->prev_chunk_sectors);
7385 	}
7386 	return err;
7387 }
7388 
7389 static unsigned long raid5_cache_scan(struct shrinker *shrink,
7390 				      struct shrink_control *sc)
7391 {
7392 	struct r5conf *conf = shrink->private_data;
7393 	unsigned long ret = SHRINK_STOP;
7394 
7395 	if (mutex_trylock(&conf->cache_size_mutex)) {
7396 		ret= 0;
7397 		while (ret < sc->nr_to_scan &&
7398 		       conf->max_nr_stripes > conf->min_nr_stripes) {
7399 			if (drop_one_stripe(conf) == 0) {
7400 				ret = SHRINK_STOP;
7401 				break;
7402 			}
7403 			ret++;
7404 		}
7405 		mutex_unlock(&conf->cache_size_mutex);
7406 	}
7407 	return ret;
7408 }
7409 
7410 static unsigned long raid5_cache_count(struct shrinker *shrink,
7411 				       struct shrink_control *sc)
7412 {
7413 	struct r5conf *conf = shrink->private_data;
7414 	int max_stripes = READ_ONCE(conf->max_nr_stripes);
7415 	int min_stripes = READ_ONCE(conf->min_nr_stripes);
7416 
7417 	if (max_stripes < min_stripes)
7418 		/* unlikely, but not impossible */
7419 		return 0;
7420 	return max_stripes - min_stripes;
7421 }
7422 
7423 static struct r5conf *setup_conf(struct mddev *mddev)
7424 {
7425 	struct r5conf *conf;
7426 	int raid_disk, memory, max_disks;
7427 	struct md_rdev *rdev;
7428 	struct disk_info *disk;
7429 	char pers_name[6];
7430 	int i;
7431 	int group_cnt;
7432 	struct r5worker_group *new_group;
7433 	int ret = -ENOMEM;
7434 
7435 	if (mddev->new_level != 5
7436 	    && mddev->new_level != 4
7437 	    && mddev->new_level != 6) {
7438 		pr_warn("md/raid:%s: raid level not set to 4/5/6 (%d)\n",
7439 			mdname(mddev), mddev->new_level);
7440 		return ERR_PTR(-EIO);
7441 	}
7442 	if ((mddev->new_level == 5
7443 	     && !algorithm_valid_raid5(mddev->new_layout)) ||
7444 	    (mddev->new_level == 6
7445 	     && !algorithm_valid_raid6(mddev->new_layout))) {
7446 		pr_warn("md/raid:%s: layout %d not supported\n",
7447 			mdname(mddev), mddev->new_layout);
7448 		return ERR_PTR(-EIO);
7449 	}
7450 	if (mddev->new_level == 6 && mddev->raid_disks < 4) {
7451 		pr_warn("md/raid:%s: not enough configured devices (%d, minimum 4)\n",
7452 			mdname(mddev), mddev->raid_disks);
7453 		return ERR_PTR(-EINVAL);
7454 	}
7455 
7456 	if (!mddev->new_chunk_sectors ||
7457 	    (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
7458 	    !is_power_of_2(mddev->new_chunk_sectors)) {
7459 		pr_warn("md/raid:%s: invalid chunk size %d\n",
7460 			mdname(mddev), mddev->new_chunk_sectors << 9);
7461 		return ERR_PTR(-EINVAL);
7462 	}
7463 
7464 	conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
7465 	if (conf == NULL)
7466 		goto abort;
7467 
7468 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
7469 	conf->stripe_size = DEFAULT_STRIPE_SIZE;
7470 	conf->stripe_shift = ilog2(DEFAULT_STRIPE_SIZE) - 9;
7471 	conf->stripe_sectors = DEFAULT_STRIPE_SIZE >> 9;
7472 #endif
7473 	INIT_LIST_HEAD(&conf->free_list);
7474 	INIT_LIST_HEAD(&conf->pending_list);
7475 	conf->pending_data = kcalloc(PENDING_IO_MAX,
7476 				     sizeof(struct r5pending_data),
7477 				     GFP_KERNEL);
7478 	if (!conf->pending_data)
7479 		goto abort;
7480 	for (i = 0; i < PENDING_IO_MAX; i++)
7481 		list_add(&conf->pending_data[i].sibling, &conf->free_list);
7482 	/* Don't enable multi-threading by default*/
7483 	if (!alloc_thread_groups(conf, 0, &group_cnt, &new_group)) {
7484 		conf->group_cnt = group_cnt;
7485 		conf->worker_cnt_per_group = 0;
7486 		conf->worker_groups = new_group;
7487 	} else
7488 		goto abort;
7489 	spin_lock_init(&conf->device_lock);
7490 	seqcount_spinlock_init(&conf->gen_lock, &conf->device_lock);
7491 	mutex_init(&conf->cache_size_mutex);
7492 
7493 	init_waitqueue_head(&conf->wait_for_quiescent);
7494 	init_waitqueue_head(&conf->wait_for_stripe);
7495 	init_waitqueue_head(&conf->wait_for_overlap);
7496 	INIT_LIST_HEAD(&conf->handle_list);
7497 	INIT_LIST_HEAD(&conf->loprio_list);
7498 	INIT_LIST_HEAD(&conf->hold_list);
7499 	INIT_LIST_HEAD(&conf->delayed_list);
7500 	INIT_LIST_HEAD(&conf->bitmap_list);
7501 	init_llist_head(&conf->released_stripes);
7502 	atomic_set(&conf->active_stripes, 0);
7503 	atomic_set(&conf->preread_active_stripes, 0);
7504 	atomic_set(&conf->active_aligned_reads, 0);
7505 	spin_lock_init(&conf->pending_bios_lock);
7506 	conf->batch_bio_dispatch = true;
7507 	rdev_for_each(rdev, mddev) {
7508 		if (test_bit(Journal, &rdev->flags))
7509 			continue;
7510 		if (bdev_nonrot(rdev->bdev)) {
7511 			conf->batch_bio_dispatch = false;
7512 			break;
7513 		}
7514 	}
7515 
7516 	conf->bypass_threshold = BYPASS_THRESHOLD;
7517 	conf->recovery_disabled = mddev->recovery_disabled - 1;
7518 
7519 	conf->raid_disks = mddev->raid_disks;
7520 	if (mddev->reshape_position == MaxSector)
7521 		conf->previous_raid_disks = mddev->raid_disks;
7522 	else
7523 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
7524 	max_disks = max(conf->raid_disks, conf->previous_raid_disks);
7525 
7526 	conf->disks = kcalloc(max_disks, sizeof(struct disk_info),
7527 			      GFP_KERNEL);
7528 
7529 	if (!conf->disks)
7530 		goto abort;
7531 
7532 	for (i = 0; i < max_disks; i++) {
7533 		conf->disks[i].extra_page = alloc_page(GFP_KERNEL);
7534 		if (!conf->disks[i].extra_page)
7535 			goto abort;
7536 	}
7537 
7538 	ret = bioset_init(&conf->bio_split, BIO_POOL_SIZE, 0, 0);
7539 	if (ret)
7540 		goto abort;
7541 	conf->mddev = mddev;
7542 
7543 	ret = -ENOMEM;
7544 	conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL);
7545 	if (!conf->stripe_hashtbl)
7546 		goto abort;
7547 
7548 	/* We init hash_locks[0] separately to that it can be used
7549 	 * as the reference lock in the spin_lock_nest_lock() call
7550 	 * in lock_all_device_hash_locks_irq in order to convince
7551 	 * lockdep that we know what we are doing.
7552 	 */
7553 	spin_lock_init(conf->hash_locks);
7554 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
7555 		spin_lock_init(conf->hash_locks + i);
7556 
7557 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
7558 		INIT_LIST_HEAD(conf->inactive_list + i);
7559 
7560 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
7561 		INIT_LIST_HEAD(conf->temp_inactive_list + i);
7562 
7563 	atomic_set(&conf->r5c_cached_full_stripes, 0);
7564 	INIT_LIST_HEAD(&conf->r5c_full_stripe_list);
7565 	atomic_set(&conf->r5c_cached_partial_stripes, 0);
7566 	INIT_LIST_HEAD(&conf->r5c_partial_stripe_list);
7567 	atomic_set(&conf->r5c_flushing_full_stripes, 0);
7568 	atomic_set(&conf->r5c_flushing_partial_stripes, 0);
7569 
7570 	conf->level = mddev->new_level;
7571 	conf->chunk_sectors = mddev->new_chunk_sectors;
7572 	ret = raid5_alloc_percpu(conf);
7573 	if (ret)
7574 		goto abort;
7575 
7576 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
7577 
7578 	ret = -EIO;
7579 	rdev_for_each(rdev, mddev) {
7580 		raid_disk = rdev->raid_disk;
7581 		if (raid_disk >= max_disks
7582 		    || raid_disk < 0 || test_bit(Journal, &rdev->flags))
7583 			continue;
7584 		disk = conf->disks + raid_disk;
7585 
7586 		if (test_bit(Replacement, &rdev->flags)) {
7587 			if (disk->replacement)
7588 				goto abort;
7589 			disk->replacement = rdev;
7590 		} else {
7591 			if (disk->rdev)
7592 				goto abort;
7593 			disk->rdev = rdev;
7594 		}
7595 
7596 		if (test_bit(In_sync, &rdev->flags)) {
7597 			pr_info("md/raid:%s: device %pg operational as raid disk %d\n",
7598 				mdname(mddev), rdev->bdev, raid_disk);
7599 		} else if (rdev->saved_raid_disk != raid_disk)
7600 			/* Cannot rely on bitmap to complete recovery */
7601 			conf->fullsync = 1;
7602 	}
7603 
7604 	conf->level = mddev->new_level;
7605 	if (conf->level == 6) {
7606 		conf->max_degraded = 2;
7607 		if (raid6_call.xor_syndrome)
7608 			conf->rmw_level = PARITY_ENABLE_RMW;
7609 		else
7610 			conf->rmw_level = PARITY_DISABLE_RMW;
7611 	} else {
7612 		conf->max_degraded = 1;
7613 		conf->rmw_level = PARITY_ENABLE_RMW;
7614 	}
7615 	conf->algorithm = mddev->new_layout;
7616 	conf->reshape_progress = mddev->reshape_position;
7617 	if (conf->reshape_progress != MaxSector) {
7618 		conf->prev_chunk_sectors = mddev->chunk_sectors;
7619 		conf->prev_algo = mddev->layout;
7620 	} else {
7621 		conf->prev_chunk_sectors = conf->chunk_sectors;
7622 		conf->prev_algo = conf->algorithm;
7623 	}
7624 
7625 	conf->min_nr_stripes = NR_STRIPES;
7626 	if (mddev->reshape_position != MaxSector) {
7627 		int stripes = max_t(int,
7628 			((mddev->chunk_sectors << 9) / RAID5_STRIPE_SIZE(conf)) * 4,
7629 			((mddev->new_chunk_sectors << 9) / RAID5_STRIPE_SIZE(conf)) * 4);
7630 		conf->min_nr_stripes = max(NR_STRIPES, stripes);
7631 		if (conf->min_nr_stripes != NR_STRIPES)
7632 			pr_info("md/raid:%s: force stripe size %d for reshape\n",
7633 				mdname(mddev), conf->min_nr_stripes);
7634 	}
7635 	memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
7636 		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
7637 	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
7638 	if (grow_stripes(conf, conf->min_nr_stripes)) {
7639 		pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
7640 			mdname(mddev), memory);
7641 		ret = -ENOMEM;
7642 		goto abort;
7643 	} else
7644 		pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
7645 	/*
7646 	 * Losing a stripe head costs more than the time to refill it,
7647 	 * it reduces the queue depth and so can hurt throughput.
7648 	 * So set it rather large, scaled by number of devices.
7649 	 */
7650 	conf->shrinker = shrinker_alloc(0, "md-raid5:%s", mdname(mddev));
7651 	if (!conf->shrinker) {
7652 		ret = -ENOMEM;
7653 		pr_warn("md/raid:%s: couldn't allocate shrinker.\n",
7654 			mdname(mddev));
7655 		goto abort;
7656 	}
7657 
7658 	conf->shrinker->seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
7659 	conf->shrinker->scan_objects = raid5_cache_scan;
7660 	conf->shrinker->count_objects = raid5_cache_count;
7661 	conf->shrinker->batch = 128;
7662 	conf->shrinker->private_data = conf;
7663 
7664 	shrinker_register(conf->shrinker);
7665 
7666 	sprintf(pers_name, "raid%d", mddev->new_level);
7667 	rcu_assign_pointer(conf->thread,
7668 			   md_register_thread(raid5d, mddev, pers_name));
7669 	if (!conf->thread) {
7670 		pr_warn("md/raid:%s: couldn't allocate thread.\n",
7671 			mdname(mddev));
7672 		ret = -ENOMEM;
7673 		goto abort;
7674 	}
7675 
7676 	return conf;
7677 
7678  abort:
7679 	if (conf)
7680 		free_conf(conf);
7681 	return ERR_PTR(ret);
7682 }
7683 
7684 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
7685 {
7686 	switch (algo) {
7687 	case ALGORITHM_PARITY_0:
7688 		if (raid_disk < max_degraded)
7689 			return 1;
7690 		break;
7691 	case ALGORITHM_PARITY_N:
7692 		if (raid_disk >= raid_disks - max_degraded)
7693 			return 1;
7694 		break;
7695 	case ALGORITHM_PARITY_0_6:
7696 		if (raid_disk == 0 ||
7697 		    raid_disk == raid_disks - 1)
7698 			return 1;
7699 		break;
7700 	case ALGORITHM_LEFT_ASYMMETRIC_6:
7701 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
7702 	case ALGORITHM_LEFT_SYMMETRIC_6:
7703 	case ALGORITHM_RIGHT_SYMMETRIC_6:
7704 		if (raid_disk == raid_disks - 1)
7705 			return 1;
7706 	}
7707 	return 0;
7708 }
7709 
7710 static int raid5_set_limits(struct mddev *mddev)
7711 {
7712 	struct r5conf *conf = mddev->private;
7713 	struct queue_limits lim;
7714 	int data_disks, stripe;
7715 	struct md_rdev *rdev;
7716 
7717 	/*
7718 	 * The read-ahead size must cover two whole stripes, which is
7719 	 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices.
7720 	 */
7721 	data_disks = conf->previous_raid_disks - conf->max_degraded;
7722 
7723 	/*
7724 	 * We can only discard a whole stripe. It doesn't make sense to
7725 	 * discard data disk but write parity disk
7726 	 */
7727 	stripe = roundup_pow_of_two(data_disks * (mddev->chunk_sectors << 9));
7728 
7729 	md_init_stacking_limits(&lim);
7730 	lim.io_min = mddev->chunk_sectors << 9;
7731 	lim.io_opt = lim.io_min * (conf->raid_disks - conf->max_degraded);
7732 	lim.features |= BLK_FEAT_RAID_PARTIAL_STRIPES_EXPENSIVE;
7733 	lim.discard_granularity = stripe;
7734 	lim.max_write_zeroes_sectors = 0;
7735 	mddev_stack_rdev_limits(mddev, &lim, 0);
7736 	rdev_for_each(rdev, mddev)
7737 		queue_limits_stack_bdev(&lim, rdev->bdev, rdev->new_data_offset,
7738 				mddev->gendisk->disk_name);
7739 
7740 	/*
7741 	 * Zeroing is required for discard, otherwise data could be lost.
7742 	 *
7743 	 * Consider a scenario: discard a stripe (the stripe could be
7744 	 * inconsistent if discard_zeroes_data is 0); write one disk of the
7745 	 * stripe (the stripe could be inconsistent again depending on which
7746 	 * disks are used to calculate parity); the disk is broken; The stripe
7747 	 * data of this disk is lost.
7748 	 *
7749 	 * We only allow DISCARD if the sysadmin has confirmed that only safe
7750 	 * devices are in use by setting a module parameter.  A better idea
7751 	 * might be to turn DISCARD into WRITE_ZEROES requests, as that is
7752 	 * required to be safe.
7753 	 */
7754 	if (!devices_handle_discard_safely ||
7755 	    lim.max_discard_sectors < (stripe >> 9) ||
7756 	    lim.discard_granularity < stripe)
7757 		lim.max_hw_discard_sectors = 0;
7758 
7759 	/*
7760 	 * Requests require having a bitmap for each stripe.
7761 	 * Limit the max sectors based on this.
7762 	 */
7763 	lim.max_hw_sectors = RAID5_MAX_REQ_STRIPES << RAID5_STRIPE_SHIFT(conf);
7764 
7765 	/* No restrictions on the number of segments in the request */
7766 	lim.max_segments = USHRT_MAX;
7767 
7768 	return queue_limits_set(mddev->gendisk->queue, &lim);
7769 }
7770 
7771 static int raid5_run(struct mddev *mddev)
7772 {
7773 	struct r5conf *conf;
7774 	int dirty_parity_disks = 0;
7775 	struct md_rdev *rdev;
7776 	struct md_rdev *journal_dev = NULL;
7777 	sector_t reshape_offset = 0;
7778 	int i;
7779 	long long min_offset_diff = 0;
7780 	int first = 1;
7781 	int ret = -EIO;
7782 
7783 	if (mddev->recovery_cp != MaxSector)
7784 		pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
7785 			  mdname(mddev));
7786 
7787 	rdev_for_each(rdev, mddev) {
7788 		long long diff;
7789 
7790 		if (test_bit(Journal, &rdev->flags)) {
7791 			journal_dev = rdev;
7792 			continue;
7793 		}
7794 		if (rdev->raid_disk < 0)
7795 			continue;
7796 		diff = (rdev->new_data_offset - rdev->data_offset);
7797 		if (first) {
7798 			min_offset_diff = diff;
7799 			first = 0;
7800 		} else if (mddev->reshape_backwards &&
7801 			 diff < min_offset_diff)
7802 			min_offset_diff = diff;
7803 		else if (!mddev->reshape_backwards &&
7804 			 diff > min_offset_diff)
7805 			min_offset_diff = diff;
7806 	}
7807 
7808 	if ((test_bit(MD_HAS_JOURNAL, &mddev->flags) || journal_dev) &&
7809 	    (mddev->bitmap_info.offset || mddev->bitmap_info.file)) {
7810 		pr_notice("md/raid:%s: array cannot have both journal and bitmap\n",
7811 			  mdname(mddev));
7812 		return -EINVAL;
7813 	}
7814 
7815 	if (mddev->reshape_position != MaxSector) {
7816 		/* Check that we can continue the reshape.
7817 		 * Difficulties arise if the stripe we would write to
7818 		 * next is at or after the stripe we would read from next.
7819 		 * For a reshape that changes the number of devices, this
7820 		 * is only possible for a very short time, and mdadm makes
7821 		 * sure that time appears to have past before assembling
7822 		 * the array.  So we fail if that time hasn't passed.
7823 		 * For a reshape that keeps the number of devices the same
7824 		 * mdadm must be monitoring the reshape can keeping the
7825 		 * critical areas read-only and backed up.  It will start
7826 		 * the array in read-only mode, so we check for that.
7827 		 */
7828 		sector_t here_new, here_old;
7829 		int old_disks;
7830 		int max_degraded = (mddev->level == 6 ? 2 : 1);
7831 		int chunk_sectors;
7832 		int new_data_disks;
7833 
7834 		if (journal_dev) {
7835 			pr_warn("md/raid:%s: don't support reshape with journal - aborting.\n",
7836 				mdname(mddev));
7837 			return -EINVAL;
7838 		}
7839 
7840 		if (mddev->new_level != mddev->level) {
7841 			pr_warn("md/raid:%s: unsupported reshape required - aborting.\n",
7842 				mdname(mddev));
7843 			return -EINVAL;
7844 		}
7845 		old_disks = mddev->raid_disks - mddev->delta_disks;
7846 		/* reshape_position must be on a new-stripe boundary, and one
7847 		 * further up in new geometry must map after here in old
7848 		 * geometry.
7849 		 * If the chunk sizes are different, then as we perform reshape
7850 		 * in units of the largest of the two, reshape_position needs
7851 		 * be a multiple of the largest chunk size times new data disks.
7852 		 */
7853 		here_new = mddev->reshape_position;
7854 		chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
7855 		new_data_disks = mddev->raid_disks - max_degraded;
7856 		if (sector_div(here_new, chunk_sectors * new_data_disks)) {
7857 			pr_warn("md/raid:%s: reshape_position not on a stripe boundary\n",
7858 				mdname(mddev));
7859 			return -EINVAL;
7860 		}
7861 		reshape_offset = here_new * chunk_sectors;
7862 		/* here_new is the stripe we will write to */
7863 		here_old = mddev->reshape_position;
7864 		sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
7865 		/* here_old is the first stripe that we might need to read
7866 		 * from */
7867 		if (mddev->delta_disks == 0) {
7868 			/* We cannot be sure it is safe to start an in-place
7869 			 * reshape.  It is only safe if user-space is monitoring
7870 			 * and taking constant backups.
7871 			 * mdadm always starts a situation like this in
7872 			 * readonly mode so it can take control before
7873 			 * allowing any writes.  So just check for that.
7874 			 */
7875 			if (abs(min_offset_diff) >= mddev->chunk_sectors &&
7876 			    abs(min_offset_diff) >= mddev->new_chunk_sectors)
7877 				/* not really in-place - so OK */;
7878 			else if (mddev->ro == 0) {
7879 				pr_warn("md/raid:%s: in-place reshape must be started in read-only mode - aborting\n",
7880 					mdname(mddev));
7881 				return -EINVAL;
7882 			}
7883 		} else if (mddev->reshape_backwards
7884 		    ? (here_new * chunk_sectors + min_offset_diff <=
7885 		       here_old * chunk_sectors)
7886 		    : (here_new * chunk_sectors >=
7887 		       here_old * chunk_sectors + (-min_offset_diff))) {
7888 			/* Reading from the same stripe as writing to - bad */
7889 			pr_warn("md/raid:%s: reshape_position too early for auto-recovery - aborting.\n",
7890 				mdname(mddev));
7891 			return -EINVAL;
7892 		}
7893 		pr_debug("md/raid:%s: reshape will continue\n", mdname(mddev));
7894 		/* OK, we should be able to continue; */
7895 	} else {
7896 		BUG_ON(mddev->level != mddev->new_level);
7897 		BUG_ON(mddev->layout != mddev->new_layout);
7898 		BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
7899 		BUG_ON(mddev->delta_disks != 0);
7900 	}
7901 
7902 	if (test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
7903 	    test_bit(MD_HAS_PPL, &mddev->flags)) {
7904 		pr_warn("md/raid:%s: using journal device and PPL not allowed - disabling PPL\n",
7905 			mdname(mddev));
7906 		clear_bit(MD_HAS_PPL, &mddev->flags);
7907 		clear_bit(MD_HAS_MULTIPLE_PPLS, &mddev->flags);
7908 	}
7909 
7910 	if (mddev->private == NULL)
7911 		conf = setup_conf(mddev);
7912 	else
7913 		conf = mddev->private;
7914 
7915 	if (IS_ERR(conf))
7916 		return PTR_ERR(conf);
7917 
7918 	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
7919 		if (!journal_dev) {
7920 			pr_warn("md/raid:%s: journal disk is missing, force array readonly\n",
7921 				mdname(mddev));
7922 			mddev->ro = 1;
7923 			set_disk_ro(mddev->gendisk, 1);
7924 		} else if (mddev->recovery_cp == MaxSector)
7925 			set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
7926 	}
7927 
7928 	conf->min_offset_diff = min_offset_diff;
7929 	rcu_assign_pointer(mddev->thread, conf->thread);
7930 	rcu_assign_pointer(conf->thread, NULL);
7931 	mddev->private = conf;
7932 
7933 	for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
7934 	     i++) {
7935 		rdev = conf->disks[i].rdev;
7936 		if (!rdev)
7937 			continue;
7938 		if (conf->disks[i].replacement &&
7939 		    conf->reshape_progress != MaxSector) {
7940 			/* replacements and reshape simply do not mix. */
7941 			pr_warn("md: cannot handle concurrent replacement and reshape.\n");
7942 			goto abort;
7943 		}
7944 		if (test_bit(In_sync, &rdev->flags))
7945 			continue;
7946 		/* This disc is not fully in-sync.  However if it
7947 		 * just stored parity (beyond the recovery_offset),
7948 		 * when we don't need to be concerned about the
7949 		 * array being dirty.
7950 		 * When reshape goes 'backwards', we never have
7951 		 * partially completed devices, so we only need
7952 		 * to worry about reshape going forwards.
7953 		 */
7954 		/* Hack because v0.91 doesn't store recovery_offset properly. */
7955 		if (mddev->major_version == 0 &&
7956 		    mddev->minor_version > 90)
7957 			rdev->recovery_offset = reshape_offset;
7958 
7959 		if (rdev->recovery_offset < reshape_offset) {
7960 			/* We need to check old and new layout */
7961 			if (!only_parity(rdev->raid_disk,
7962 					 conf->algorithm,
7963 					 conf->raid_disks,
7964 					 conf->max_degraded))
7965 				continue;
7966 		}
7967 		if (!only_parity(rdev->raid_disk,
7968 				 conf->prev_algo,
7969 				 conf->previous_raid_disks,
7970 				 conf->max_degraded))
7971 			continue;
7972 		dirty_parity_disks++;
7973 	}
7974 
7975 	/*
7976 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
7977 	 */
7978 	mddev->degraded = raid5_calc_degraded(conf);
7979 
7980 	if (has_failed(conf)) {
7981 		pr_crit("md/raid:%s: not enough operational devices (%d/%d failed)\n",
7982 			mdname(mddev), mddev->degraded, conf->raid_disks);
7983 		goto abort;
7984 	}
7985 
7986 	/* device size must be a multiple of chunk size */
7987 	mddev->dev_sectors &= ~((sector_t)mddev->chunk_sectors - 1);
7988 	mddev->resync_max_sectors = mddev->dev_sectors;
7989 
7990 	if (mddev->degraded > dirty_parity_disks &&
7991 	    mddev->recovery_cp != MaxSector) {
7992 		if (test_bit(MD_HAS_PPL, &mddev->flags))
7993 			pr_crit("md/raid:%s: starting dirty degraded array with PPL.\n",
7994 				mdname(mddev));
7995 		else if (mddev->ok_start_degraded)
7996 			pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
7997 				mdname(mddev));
7998 		else {
7999 			pr_crit("md/raid:%s: cannot start dirty degraded array.\n",
8000 				mdname(mddev));
8001 			goto abort;
8002 		}
8003 	}
8004 
8005 	pr_info("md/raid:%s: raid level %d active with %d out of %d devices, algorithm %d\n",
8006 		mdname(mddev), conf->level,
8007 		mddev->raid_disks-mddev->degraded, mddev->raid_disks,
8008 		mddev->new_layout);
8009 
8010 	print_raid5_conf(conf);
8011 
8012 	if (conf->reshape_progress != MaxSector) {
8013 		conf->reshape_safe = conf->reshape_progress;
8014 		atomic_set(&conf->reshape_stripes, 0);
8015 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
8016 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
8017 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
8018 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
8019 	}
8020 
8021 	/* Ok, everything is just fine now */
8022 	if (mddev->to_remove == &raid5_attrs_group)
8023 		mddev->to_remove = NULL;
8024 	else if (mddev->kobj.sd &&
8025 	    sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
8026 		pr_warn("raid5: failed to create sysfs attributes for %s\n",
8027 			mdname(mddev));
8028 	md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
8029 
8030 	if (!mddev_is_dm(mddev)) {
8031 		ret = raid5_set_limits(mddev);
8032 		if (ret)
8033 			goto abort;
8034 	}
8035 
8036 	if (log_init(conf, journal_dev, raid5_has_ppl(conf)))
8037 		goto abort;
8038 
8039 	return 0;
8040 abort:
8041 	md_unregister_thread(mddev, &mddev->thread);
8042 	print_raid5_conf(conf);
8043 	free_conf(conf);
8044 	mddev->private = NULL;
8045 	pr_warn("md/raid:%s: failed to run raid set.\n", mdname(mddev));
8046 	return ret;
8047 }
8048 
8049 static void raid5_free(struct mddev *mddev, void *priv)
8050 {
8051 	struct r5conf *conf = priv;
8052 
8053 	free_conf(conf);
8054 	mddev->to_remove = &raid5_attrs_group;
8055 }
8056 
8057 static void raid5_status(struct seq_file *seq, struct mddev *mddev)
8058 {
8059 	struct r5conf *conf = mddev->private;
8060 	int i;
8061 
8062 	lockdep_assert_held(&mddev->lock);
8063 
8064 	seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
8065 		conf->chunk_sectors / 2, mddev->layout);
8066 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
8067 	for (i = 0; i < conf->raid_disks; i++) {
8068 		struct md_rdev *rdev = READ_ONCE(conf->disks[i].rdev);
8069 
8070 		seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
8071 	}
8072 	seq_printf (seq, "]");
8073 }
8074 
8075 static void print_raid5_conf(struct r5conf *conf)
8076 {
8077 	struct md_rdev *rdev;
8078 	int i;
8079 
8080 	pr_debug("RAID conf printout:\n");
8081 	if (!conf) {
8082 		pr_debug("(conf==NULL)\n");
8083 		return;
8084 	}
8085 	pr_debug(" --- level:%d rd:%d wd:%d\n", conf->level,
8086 	       conf->raid_disks,
8087 	       conf->raid_disks - conf->mddev->degraded);
8088 
8089 	for (i = 0; i < conf->raid_disks; i++) {
8090 		rdev = conf->disks[i].rdev;
8091 		if (rdev)
8092 			pr_debug(" disk %d, o:%d, dev:%pg\n",
8093 			       i, !test_bit(Faulty, &rdev->flags),
8094 			       rdev->bdev);
8095 	}
8096 }
8097 
8098 static int raid5_spare_active(struct mddev *mddev)
8099 {
8100 	int i;
8101 	struct r5conf *conf = mddev->private;
8102 	struct md_rdev *rdev, *replacement;
8103 	int count = 0;
8104 	unsigned long flags;
8105 
8106 	for (i = 0; i < conf->raid_disks; i++) {
8107 		rdev = conf->disks[i].rdev;
8108 		replacement = conf->disks[i].replacement;
8109 		if (replacement
8110 		    && replacement->recovery_offset == MaxSector
8111 		    && !test_bit(Faulty, &replacement->flags)
8112 		    && !test_and_set_bit(In_sync, &replacement->flags)) {
8113 			/* Replacement has just become active. */
8114 			if (!rdev
8115 			    || !test_and_clear_bit(In_sync, &rdev->flags))
8116 				count++;
8117 			if (rdev) {
8118 				/* Replaced device not technically faulty,
8119 				 * but we need to be sure it gets removed
8120 				 * and never re-added.
8121 				 */
8122 				set_bit(Faulty, &rdev->flags);
8123 				sysfs_notify_dirent_safe(
8124 					rdev->sysfs_state);
8125 			}
8126 			sysfs_notify_dirent_safe(replacement->sysfs_state);
8127 		} else if (rdev
8128 		    && rdev->recovery_offset == MaxSector
8129 		    && !test_bit(Faulty, &rdev->flags)
8130 		    && !test_and_set_bit(In_sync, &rdev->flags)) {
8131 			count++;
8132 			sysfs_notify_dirent_safe(rdev->sysfs_state);
8133 		}
8134 	}
8135 	spin_lock_irqsave(&conf->device_lock, flags);
8136 	mddev->degraded = raid5_calc_degraded(conf);
8137 	spin_unlock_irqrestore(&conf->device_lock, flags);
8138 	print_raid5_conf(conf);
8139 	return count;
8140 }
8141 
8142 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
8143 {
8144 	struct r5conf *conf = mddev->private;
8145 	int err = 0;
8146 	int number = rdev->raid_disk;
8147 	struct md_rdev **rdevp;
8148 	struct disk_info *p;
8149 	struct md_rdev *tmp;
8150 
8151 	print_raid5_conf(conf);
8152 	if (test_bit(Journal, &rdev->flags) && conf->log) {
8153 		/*
8154 		 * we can't wait pending write here, as this is called in
8155 		 * raid5d, wait will deadlock.
8156 		 * neilb: there is no locking about new writes here,
8157 		 * so this cannot be safe.
8158 		 */
8159 		if (atomic_read(&conf->active_stripes) ||
8160 		    atomic_read(&conf->r5c_cached_full_stripes) ||
8161 		    atomic_read(&conf->r5c_cached_partial_stripes)) {
8162 			return -EBUSY;
8163 		}
8164 		log_exit(conf);
8165 		return 0;
8166 	}
8167 	if (unlikely(number >= conf->pool_size))
8168 		return 0;
8169 	p = conf->disks + number;
8170 	if (rdev == p->rdev)
8171 		rdevp = &p->rdev;
8172 	else if (rdev == p->replacement)
8173 		rdevp = &p->replacement;
8174 	else
8175 		return 0;
8176 
8177 	if (number >= conf->raid_disks &&
8178 	    conf->reshape_progress == MaxSector)
8179 		clear_bit(In_sync, &rdev->flags);
8180 
8181 	if (test_bit(In_sync, &rdev->flags) ||
8182 	    atomic_read(&rdev->nr_pending)) {
8183 		err = -EBUSY;
8184 		goto abort;
8185 	}
8186 	/* Only remove non-faulty devices if recovery
8187 	 * isn't possible.
8188 	 */
8189 	if (!test_bit(Faulty, &rdev->flags) &&
8190 	    mddev->recovery_disabled != conf->recovery_disabled &&
8191 	    !has_failed(conf) &&
8192 	    (!p->replacement || p->replacement == rdev) &&
8193 	    number < conf->raid_disks) {
8194 		err = -EBUSY;
8195 		goto abort;
8196 	}
8197 	WRITE_ONCE(*rdevp, NULL);
8198 	if (!err) {
8199 		err = log_modify(conf, rdev, false);
8200 		if (err)
8201 			goto abort;
8202 	}
8203 
8204 	tmp = p->replacement;
8205 	if (tmp) {
8206 		/* We must have just cleared 'rdev' */
8207 		WRITE_ONCE(p->rdev, tmp);
8208 		clear_bit(Replacement, &tmp->flags);
8209 		WRITE_ONCE(p->replacement, NULL);
8210 
8211 		if (!err)
8212 			err = log_modify(conf, tmp, true);
8213 	}
8214 
8215 	clear_bit(WantReplacement, &rdev->flags);
8216 abort:
8217 
8218 	print_raid5_conf(conf);
8219 	return err;
8220 }
8221 
8222 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
8223 {
8224 	struct r5conf *conf = mddev->private;
8225 	int ret, err = -EEXIST;
8226 	int disk;
8227 	struct disk_info *p;
8228 	struct md_rdev *tmp;
8229 	int first = 0;
8230 	int last = conf->raid_disks - 1;
8231 
8232 	if (test_bit(Journal, &rdev->flags)) {
8233 		if (conf->log)
8234 			return -EBUSY;
8235 
8236 		rdev->raid_disk = 0;
8237 		/*
8238 		 * The array is in readonly mode if journal is missing, so no
8239 		 * write requests running. We should be safe
8240 		 */
8241 		ret = log_init(conf, rdev, false);
8242 		if (ret)
8243 			return ret;
8244 
8245 		ret = r5l_start(conf->log);
8246 		if (ret)
8247 			return ret;
8248 
8249 		return 0;
8250 	}
8251 	if (mddev->recovery_disabled == conf->recovery_disabled)
8252 		return -EBUSY;
8253 
8254 	if (rdev->saved_raid_disk < 0 && has_failed(conf))
8255 		/* no point adding a device */
8256 		return -EINVAL;
8257 
8258 	if (rdev->raid_disk >= 0)
8259 		first = last = rdev->raid_disk;
8260 
8261 	/*
8262 	 * find the disk ... but prefer rdev->saved_raid_disk
8263 	 * if possible.
8264 	 */
8265 	if (rdev->saved_raid_disk >= first &&
8266 	    rdev->saved_raid_disk <= last &&
8267 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
8268 		first = rdev->saved_raid_disk;
8269 
8270 	for (disk = first; disk <= last; disk++) {
8271 		p = conf->disks + disk;
8272 		if (p->rdev == NULL) {
8273 			clear_bit(In_sync, &rdev->flags);
8274 			rdev->raid_disk = disk;
8275 			if (rdev->saved_raid_disk != disk)
8276 				conf->fullsync = 1;
8277 			WRITE_ONCE(p->rdev, rdev);
8278 
8279 			err = log_modify(conf, rdev, true);
8280 
8281 			goto out;
8282 		}
8283 	}
8284 	for (disk = first; disk <= last; disk++) {
8285 		p = conf->disks + disk;
8286 		tmp = p->rdev;
8287 		if (test_bit(WantReplacement, &tmp->flags) &&
8288 		    mddev->reshape_position == MaxSector &&
8289 		    p->replacement == NULL) {
8290 			clear_bit(In_sync, &rdev->flags);
8291 			set_bit(Replacement, &rdev->flags);
8292 			rdev->raid_disk = disk;
8293 			err = 0;
8294 			conf->fullsync = 1;
8295 			WRITE_ONCE(p->replacement, rdev);
8296 			break;
8297 		}
8298 	}
8299 out:
8300 	print_raid5_conf(conf);
8301 	return err;
8302 }
8303 
8304 static int raid5_resize(struct mddev *mddev, sector_t sectors)
8305 {
8306 	/* no resync is happening, and there is enough space
8307 	 * on all devices, so we can resize.
8308 	 * We need to make sure resync covers any new space.
8309 	 * If the array is shrinking we should possibly wait until
8310 	 * any io in the removed space completes, but it hardly seems
8311 	 * worth it.
8312 	 */
8313 	sector_t newsize;
8314 	struct r5conf *conf = mddev->private;
8315 
8316 	if (raid5_has_log(conf) || raid5_has_ppl(conf))
8317 		return -EINVAL;
8318 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
8319 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
8320 	if (mddev->external_size &&
8321 	    mddev->array_sectors > newsize)
8322 		return -EINVAL;
8323 	if (mddev->bitmap) {
8324 		int ret = md_bitmap_resize(mddev->bitmap, sectors, 0, 0);
8325 		if (ret)
8326 			return ret;
8327 	}
8328 	md_set_array_sectors(mddev, newsize);
8329 	if (sectors > mddev->dev_sectors &&
8330 	    mddev->recovery_cp > mddev->dev_sectors) {
8331 		mddev->recovery_cp = mddev->dev_sectors;
8332 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
8333 	}
8334 	mddev->dev_sectors = sectors;
8335 	mddev->resync_max_sectors = sectors;
8336 	return 0;
8337 }
8338 
8339 static int check_stripe_cache(struct mddev *mddev)
8340 {
8341 	/* Can only proceed if there are plenty of stripe_heads.
8342 	 * We need a minimum of one full stripe,, and for sensible progress
8343 	 * it is best to have about 4 times that.
8344 	 * If we require 4 times, then the default 256 4K stripe_heads will
8345 	 * allow for chunk sizes up to 256K, which is probably OK.
8346 	 * If the chunk size is greater, user-space should request more
8347 	 * stripe_heads first.
8348 	 */
8349 	struct r5conf *conf = mddev->private;
8350 	if (((mddev->chunk_sectors << 9) / RAID5_STRIPE_SIZE(conf)) * 4
8351 	    > conf->min_nr_stripes ||
8352 	    ((mddev->new_chunk_sectors << 9) / RAID5_STRIPE_SIZE(conf)) * 4
8353 	    > conf->min_nr_stripes) {
8354 		pr_warn("md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
8355 			mdname(mddev),
8356 			((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
8357 			 / RAID5_STRIPE_SIZE(conf))*4);
8358 		return 0;
8359 	}
8360 	return 1;
8361 }
8362 
8363 static int check_reshape(struct mddev *mddev)
8364 {
8365 	struct r5conf *conf = mddev->private;
8366 
8367 	if (raid5_has_log(conf) || raid5_has_ppl(conf))
8368 		return -EINVAL;
8369 	if (mddev->delta_disks == 0 &&
8370 	    mddev->new_layout == mddev->layout &&
8371 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
8372 		return 0; /* nothing to do */
8373 	if (has_failed(conf))
8374 		return -EINVAL;
8375 	if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
8376 		/* We might be able to shrink, but the devices must
8377 		 * be made bigger first.
8378 		 * For raid6, 4 is the minimum size.
8379 		 * Otherwise 2 is the minimum
8380 		 */
8381 		int min = 2;
8382 		if (mddev->level == 6)
8383 			min = 4;
8384 		if (mddev->raid_disks + mddev->delta_disks < min)
8385 			return -EINVAL;
8386 	}
8387 
8388 	if (!check_stripe_cache(mddev))
8389 		return -ENOSPC;
8390 
8391 	if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
8392 	    mddev->delta_disks > 0)
8393 		if (resize_chunks(conf,
8394 				  conf->previous_raid_disks
8395 				  + max(0, mddev->delta_disks),
8396 				  max(mddev->new_chunk_sectors,
8397 				      mddev->chunk_sectors)
8398 			    ) < 0)
8399 			return -ENOMEM;
8400 
8401 	if (conf->previous_raid_disks + mddev->delta_disks <= conf->pool_size)
8402 		return 0; /* never bother to shrink */
8403 	return resize_stripes(conf, (conf->previous_raid_disks
8404 				     + mddev->delta_disks));
8405 }
8406 
8407 static int raid5_start_reshape(struct mddev *mddev)
8408 {
8409 	struct r5conf *conf = mddev->private;
8410 	struct md_rdev *rdev;
8411 	int spares = 0;
8412 	int i;
8413 	unsigned long flags;
8414 
8415 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
8416 		return -EBUSY;
8417 
8418 	if (!check_stripe_cache(mddev))
8419 		return -ENOSPC;
8420 
8421 	if (has_failed(conf))
8422 		return -EINVAL;
8423 
8424 	/* raid5 can't handle concurrent reshape and recovery */
8425 	if (mddev->recovery_cp < MaxSector)
8426 		return -EBUSY;
8427 	for (i = 0; i < conf->raid_disks; i++)
8428 		if (conf->disks[i].replacement)
8429 			return -EBUSY;
8430 
8431 	rdev_for_each(rdev, mddev) {
8432 		if (!test_bit(In_sync, &rdev->flags)
8433 		    && !test_bit(Faulty, &rdev->flags))
8434 			spares++;
8435 	}
8436 
8437 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
8438 		/* Not enough devices even to make a degraded array
8439 		 * of that size
8440 		 */
8441 		return -EINVAL;
8442 
8443 	/* Refuse to reduce size of the array.  Any reductions in
8444 	 * array size must be through explicit setting of array_size
8445 	 * attribute.
8446 	 */
8447 	if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
8448 	    < mddev->array_sectors) {
8449 		pr_warn("md/raid:%s: array size must be reduced before number of disks\n",
8450 			mdname(mddev));
8451 		return -EINVAL;
8452 	}
8453 
8454 	atomic_set(&conf->reshape_stripes, 0);
8455 	spin_lock_irq(&conf->device_lock);
8456 	write_seqcount_begin(&conf->gen_lock);
8457 	conf->previous_raid_disks = conf->raid_disks;
8458 	conf->raid_disks += mddev->delta_disks;
8459 	conf->prev_chunk_sectors = conf->chunk_sectors;
8460 	conf->chunk_sectors = mddev->new_chunk_sectors;
8461 	conf->prev_algo = conf->algorithm;
8462 	conf->algorithm = mddev->new_layout;
8463 	conf->generation++;
8464 	/* Code that selects data_offset needs to see the generation update
8465 	 * if reshape_progress has been set - so a memory barrier needed.
8466 	 */
8467 	smp_mb();
8468 	if (mddev->reshape_backwards)
8469 		conf->reshape_progress = raid5_size(mddev, 0, 0);
8470 	else
8471 		conf->reshape_progress = 0;
8472 	conf->reshape_safe = conf->reshape_progress;
8473 	write_seqcount_end(&conf->gen_lock);
8474 	spin_unlock_irq(&conf->device_lock);
8475 
8476 	/* Now make sure any requests that proceeded on the assumption
8477 	 * the reshape wasn't running - like Discard or Read - have
8478 	 * completed.
8479 	 */
8480 	raid5_quiesce(mddev, true);
8481 	raid5_quiesce(mddev, false);
8482 
8483 	/* Add some new drives, as many as will fit.
8484 	 * We know there are enough to make the newly sized array work.
8485 	 * Don't add devices if we are reducing the number of
8486 	 * devices in the array.  This is because it is not possible
8487 	 * to correctly record the "partially reconstructed" state of
8488 	 * such devices during the reshape and confusion could result.
8489 	 */
8490 	if (mddev->delta_disks >= 0) {
8491 		rdev_for_each(rdev, mddev)
8492 			if (rdev->raid_disk < 0 &&
8493 			    !test_bit(Faulty, &rdev->flags)) {
8494 				if (raid5_add_disk(mddev, rdev) == 0) {
8495 					if (rdev->raid_disk
8496 					    >= conf->previous_raid_disks)
8497 						set_bit(In_sync, &rdev->flags);
8498 					else
8499 						rdev->recovery_offset = 0;
8500 
8501 					/* Failure here is OK */
8502 					sysfs_link_rdev(mddev, rdev);
8503 				}
8504 			} else if (rdev->raid_disk >= conf->previous_raid_disks
8505 				   && !test_bit(Faulty, &rdev->flags)) {
8506 				/* This is a spare that was manually added */
8507 				set_bit(In_sync, &rdev->flags);
8508 			}
8509 
8510 		/* When a reshape changes the number of devices,
8511 		 * ->degraded is measured against the larger of the
8512 		 * pre and post number of devices.
8513 		 */
8514 		spin_lock_irqsave(&conf->device_lock, flags);
8515 		mddev->degraded = raid5_calc_degraded(conf);
8516 		spin_unlock_irqrestore(&conf->device_lock, flags);
8517 	}
8518 	mddev->raid_disks = conf->raid_disks;
8519 	mddev->reshape_position = conf->reshape_progress;
8520 	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
8521 
8522 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
8523 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
8524 	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
8525 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
8526 	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
8527 	conf->reshape_checkpoint = jiffies;
8528 	md_new_event();
8529 	return 0;
8530 }
8531 
8532 /* This is called from the reshape thread and should make any
8533  * changes needed in 'conf'
8534  */
8535 static void end_reshape(struct r5conf *conf)
8536 {
8537 
8538 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
8539 		struct md_rdev *rdev;
8540 
8541 		spin_lock_irq(&conf->device_lock);
8542 		conf->previous_raid_disks = conf->raid_disks;
8543 		md_finish_reshape(conf->mddev);
8544 		smp_wmb();
8545 		conf->reshape_progress = MaxSector;
8546 		conf->mddev->reshape_position = MaxSector;
8547 		rdev_for_each(rdev, conf->mddev)
8548 			if (rdev->raid_disk >= 0 &&
8549 			    !test_bit(Journal, &rdev->flags) &&
8550 			    !test_bit(In_sync, &rdev->flags))
8551 				rdev->recovery_offset = MaxSector;
8552 		spin_unlock_irq(&conf->device_lock);
8553 		wake_up(&conf->wait_for_overlap);
8554 
8555 		mddev_update_io_opt(conf->mddev,
8556 			conf->raid_disks - conf->max_degraded);
8557 	}
8558 }
8559 
8560 /* This is called from the raid5d thread with mddev_lock held.
8561  * It makes config changes to the device.
8562  */
8563 static void raid5_finish_reshape(struct mddev *mddev)
8564 {
8565 	struct r5conf *conf = mddev->private;
8566 	struct md_rdev *rdev;
8567 
8568 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
8569 
8570 		if (mddev->delta_disks <= 0) {
8571 			int d;
8572 			spin_lock_irq(&conf->device_lock);
8573 			mddev->degraded = raid5_calc_degraded(conf);
8574 			spin_unlock_irq(&conf->device_lock);
8575 			for (d = conf->raid_disks ;
8576 			     d < conf->raid_disks - mddev->delta_disks;
8577 			     d++) {
8578 				rdev = conf->disks[d].rdev;
8579 				if (rdev)
8580 					clear_bit(In_sync, &rdev->flags);
8581 				rdev = conf->disks[d].replacement;
8582 				if (rdev)
8583 					clear_bit(In_sync, &rdev->flags);
8584 			}
8585 		}
8586 		mddev->layout = conf->algorithm;
8587 		mddev->chunk_sectors = conf->chunk_sectors;
8588 		mddev->reshape_position = MaxSector;
8589 		mddev->delta_disks = 0;
8590 		mddev->reshape_backwards = 0;
8591 	}
8592 }
8593 
8594 static void raid5_quiesce(struct mddev *mddev, int quiesce)
8595 {
8596 	struct r5conf *conf = mddev->private;
8597 
8598 	if (quiesce) {
8599 		/* stop all writes */
8600 		lock_all_device_hash_locks_irq(conf);
8601 		/* '2' tells resync/reshape to pause so that all
8602 		 * active stripes can drain
8603 		 */
8604 		r5c_flush_cache(conf, INT_MAX);
8605 		/* need a memory barrier to make sure read_one_chunk() sees
8606 		 * quiesce started and reverts to slow (locked) path.
8607 		 */
8608 		smp_store_release(&conf->quiesce, 2);
8609 		wait_event_cmd(conf->wait_for_quiescent,
8610 				    atomic_read(&conf->active_stripes) == 0 &&
8611 				    atomic_read(&conf->active_aligned_reads) == 0,
8612 				    unlock_all_device_hash_locks_irq(conf),
8613 				    lock_all_device_hash_locks_irq(conf));
8614 		conf->quiesce = 1;
8615 		unlock_all_device_hash_locks_irq(conf);
8616 		/* allow reshape to continue */
8617 		wake_up(&conf->wait_for_overlap);
8618 	} else {
8619 		/* re-enable writes */
8620 		lock_all_device_hash_locks_irq(conf);
8621 		conf->quiesce = 0;
8622 		wake_up(&conf->wait_for_quiescent);
8623 		wake_up(&conf->wait_for_overlap);
8624 		unlock_all_device_hash_locks_irq(conf);
8625 	}
8626 	log_quiesce(conf, quiesce);
8627 }
8628 
8629 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
8630 {
8631 	struct r0conf *raid0_conf = mddev->private;
8632 	sector_t sectors;
8633 
8634 	/* for raid0 takeover only one zone is supported */
8635 	if (raid0_conf->nr_strip_zones > 1) {
8636 		pr_warn("md/raid:%s: cannot takeover raid0 with more than one zone.\n",
8637 			mdname(mddev));
8638 		return ERR_PTR(-EINVAL);
8639 	}
8640 
8641 	sectors = raid0_conf->strip_zone[0].zone_end;
8642 	sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
8643 	mddev->dev_sectors = sectors;
8644 	mddev->new_level = level;
8645 	mddev->new_layout = ALGORITHM_PARITY_N;
8646 	mddev->new_chunk_sectors = mddev->chunk_sectors;
8647 	mddev->raid_disks += 1;
8648 	mddev->delta_disks = 1;
8649 	/* make sure it will be not marked as dirty */
8650 	mddev->recovery_cp = MaxSector;
8651 
8652 	return setup_conf(mddev);
8653 }
8654 
8655 static void *raid5_takeover_raid1(struct mddev *mddev)
8656 {
8657 	int chunksect;
8658 	void *ret;
8659 
8660 	if (mddev->raid_disks != 2 ||
8661 	    mddev->degraded > 1)
8662 		return ERR_PTR(-EINVAL);
8663 
8664 	/* Should check if there are write-behind devices? */
8665 
8666 	chunksect = 64*2; /* 64K by default */
8667 
8668 	/* The array must be an exact multiple of chunksize */
8669 	while (chunksect && (mddev->array_sectors & (chunksect-1)))
8670 		chunksect >>= 1;
8671 
8672 	if ((chunksect<<9) < RAID5_STRIPE_SIZE((struct r5conf *)mddev->private))
8673 		/* array size does not allow a suitable chunk size */
8674 		return ERR_PTR(-EINVAL);
8675 
8676 	mddev->new_level = 5;
8677 	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
8678 	mddev->new_chunk_sectors = chunksect;
8679 
8680 	ret = setup_conf(mddev);
8681 	if (!IS_ERR(ret))
8682 		mddev_clear_unsupported_flags(mddev,
8683 			UNSUPPORTED_MDDEV_FLAGS);
8684 	return ret;
8685 }
8686 
8687 static void *raid5_takeover_raid6(struct mddev *mddev)
8688 {
8689 	int new_layout;
8690 
8691 	switch (mddev->layout) {
8692 	case ALGORITHM_LEFT_ASYMMETRIC_6:
8693 		new_layout = ALGORITHM_LEFT_ASYMMETRIC;
8694 		break;
8695 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
8696 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
8697 		break;
8698 	case ALGORITHM_LEFT_SYMMETRIC_6:
8699 		new_layout = ALGORITHM_LEFT_SYMMETRIC;
8700 		break;
8701 	case ALGORITHM_RIGHT_SYMMETRIC_6:
8702 		new_layout = ALGORITHM_RIGHT_SYMMETRIC;
8703 		break;
8704 	case ALGORITHM_PARITY_0_6:
8705 		new_layout = ALGORITHM_PARITY_0;
8706 		break;
8707 	case ALGORITHM_PARITY_N:
8708 		new_layout = ALGORITHM_PARITY_N;
8709 		break;
8710 	default:
8711 		return ERR_PTR(-EINVAL);
8712 	}
8713 	mddev->new_level = 5;
8714 	mddev->new_layout = new_layout;
8715 	mddev->delta_disks = -1;
8716 	mddev->raid_disks -= 1;
8717 	return setup_conf(mddev);
8718 }
8719 
8720 static int raid5_check_reshape(struct mddev *mddev)
8721 {
8722 	/* For a 2-drive array, the layout and chunk size can be changed
8723 	 * immediately as not restriping is needed.
8724 	 * For larger arrays we record the new value - after validation
8725 	 * to be used by a reshape pass.
8726 	 */
8727 	struct r5conf *conf = mddev->private;
8728 	int new_chunk = mddev->new_chunk_sectors;
8729 
8730 	if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
8731 		return -EINVAL;
8732 	if (new_chunk > 0) {
8733 		if (!is_power_of_2(new_chunk))
8734 			return -EINVAL;
8735 		if (new_chunk < (PAGE_SIZE>>9))
8736 			return -EINVAL;
8737 		if (mddev->array_sectors & (new_chunk-1))
8738 			/* not factor of array size */
8739 			return -EINVAL;
8740 	}
8741 
8742 	/* They look valid */
8743 
8744 	if (mddev->raid_disks == 2) {
8745 		/* can make the change immediately */
8746 		if (mddev->new_layout >= 0) {
8747 			conf->algorithm = mddev->new_layout;
8748 			mddev->layout = mddev->new_layout;
8749 		}
8750 		if (new_chunk > 0) {
8751 			conf->chunk_sectors = new_chunk ;
8752 			mddev->chunk_sectors = new_chunk;
8753 		}
8754 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
8755 		md_wakeup_thread(mddev->thread);
8756 	}
8757 	return check_reshape(mddev);
8758 }
8759 
8760 static int raid6_check_reshape(struct mddev *mddev)
8761 {
8762 	int new_chunk = mddev->new_chunk_sectors;
8763 
8764 	if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
8765 		return -EINVAL;
8766 	if (new_chunk > 0) {
8767 		if (!is_power_of_2(new_chunk))
8768 			return -EINVAL;
8769 		if (new_chunk < (PAGE_SIZE >> 9))
8770 			return -EINVAL;
8771 		if (mddev->array_sectors & (new_chunk-1))
8772 			/* not factor of array size */
8773 			return -EINVAL;
8774 	}
8775 
8776 	/* They look valid */
8777 	return check_reshape(mddev);
8778 }
8779 
8780 static void *raid5_takeover(struct mddev *mddev)
8781 {
8782 	/* raid5 can take over:
8783 	 *  raid0 - if there is only one strip zone - make it a raid4 layout
8784 	 *  raid1 - if there are two drives.  We need to know the chunk size
8785 	 *  raid4 - trivial - just use a raid4 layout.
8786 	 *  raid6 - Providing it is a *_6 layout
8787 	 */
8788 	if (mddev->level == 0)
8789 		return raid45_takeover_raid0(mddev, 5);
8790 	if (mddev->level == 1)
8791 		return raid5_takeover_raid1(mddev);
8792 	if (mddev->level == 4) {
8793 		mddev->new_layout = ALGORITHM_PARITY_N;
8794 		mddev->new_level = 5;
8795 		return setup_conf(mddev);
8796 	}
8797 	if (mddev->level == 6)
8798 		return raid5_takeover_raid6(mddev);
8799 
8800 	return ERR_PTR(-EINVAL);
8801 }
8802 
8803 static void *raid4_takeover(struct mddev *mddev)
8804 {
8805 	/* raid4 can take over:
8806 	 *  raid0 - if there is only one strip zone
8807 	 *  raid5 - if layout is right
8808 	 */
8809 	if (mddev->level == 0)
8810 		return raid45_takeover_raid0(mddev, 4);
8811 	if (mddev->level == 5 &&
8812 	    mddev->layout == ALGORITHM_PARITY_N) {
8813 		mddev->new_layout = 0;
8814 		mddev->new_level = 4;
8815 		return setup_conf(mddev);
8816 	}
8817 	return ERR_PTR(-EINVAL);
8818 }
8819 
8820 static struct md_personality raid5_personality;
8821 
8822 static void *raid6_takeover(struct mddev *mddev)
8823 {
8824 	/* Currently can only take over a raid5.  We map the
8825 	 * personality to an equivalent raid6 personality
8826 	 * with the Q block at the end.
8827 	 */
8828 	int new_layout;
8829 
8830 	if (mddev->pers != &raid5_personality)
8831 		return ERR_PTR(-EINVAL);
8832 	if (mddev->degraded > 1)
8833 		return ERR_PTR(-EINVAL);
8834 	if (mddev->raid_disks > 253)
8835 		return ERR_PTR(-EINVAL);
8836 	if (mddev->raid_disks < 3)
8837 		return ERR_PTR(-EINVAL);
8838 
8839 	switch (mddev->layout) {
8840 	case ALGORITHM_LEFT_ASYMMETRIC:
8841 		new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
8842 		break;
8843 	case ALGORITHM_RIGHT_ASYMMETRIC:
8844 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
8845 		break;
8846 	case ALGORITHM_LEFT_SYMMETRIC:
8847 		new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
8848 		break;
8849 	case ALGORITHM_RIGHT_SYMMETRIC:
8850 		new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
8851 		break;
8852 	case ALGORITHM_PARITY_0:
8853 		new_layout = ALGORITHM_PARITY_0_6;
8854 		break;
8855 	case ALGORITHM_PARITY_N:
8856 		new_layout = ALGORITHM_PARITY_N;
8857 		break;
8858 	default:
8859 		return ERR_PTR(-EINVAL);
8860 	}
8861 	mddev->new_level = 6;
8862 	mddev->new_layout = new_layout;
8863 	mddev->delta_disks = 1;
8864 	mddev->raid_disks += 1;
8865 	return setup_conf(mddev);
8866 }
8867 
8868 static int raid5_change_consistency_policy(struct mddev *mddev, const char *buf)
8869 {
8870 	struct r5conf *conf;
8871 	int err;
8872 
8873 	err = mddev_suspend_and_lock(mddev);
8874 	if (err)
8875 		return err;
8876 	conf = mddev->private;
8877 	if (!conf) {
8878 		mddev_unlock_and_resume(mddev);
8879 		return -ENODEV;
8880 	}
8881 
8882 	if (strncmp(buf, "ppl", 3) == 0) {
8883 		/* ppl only works with RAID 5 */
8884 		if (!raid5_has_ppl(conf) && conf->level == 5) {
8885 			err = log_init(conf, NULL, true);
8886 			if (!err) {
8887 				err = resize_stripes(conf, conf->pool_size);
8888 				if (err)
8889 					log_exit(conf);
8890 			}
8891 		} else
8892 			err = -EINVAL;
8893 	} else if (strncmp(buf, "resync", 6) == 0) {
8894 		if (raid5_has_ppl(conf)) {
8895 			log_exit(conf);
8896 			err = resize_stripes(conf, conf->pool_size);
8897 		} else if (test_bit(MD_HAS_JOURNAL, &conf->mddev->flags) &&
8898 			   r5l_log_disk_error(conf)) {
8899 			bool journal_dev_exists = false;
8900 			struct md_rdev *rdev;
8901 
8902 			rdev_for_each(rdev, mddev)
8903 				if (test_bit(Journal, &rdev->flags)) {
8904 					journal_dev_exists = true;
8905 					break;
8906 				}
8907 
8908 			if (!journal_dev_exists)
8909 				clear_bit(MD_HAS_JOURNAL, &mddev->flags);
8910 			else  /* need remove journal device first */
8911 				err = -EBUSY;
8912 		} else
8913 			err = -EINVAL;
8914 	} else {
8915 		err = -EINVAL;
8916 	}
8917 
8918 	if (!err)
8919 		md_update_sb(mddev, 1);
8920 
8921 	mddev_unlock_and_resume(mddev);
8922 
8923 	return err;
8924 }
8925 
8926 static int raid5_start(struct mddev *mddev)
8927 {
8928 	struct r5conf *conf = mddev->private;
8929 
8930 	return r5l_start(conf->log);
8931 }
8932 
8933 /*
8934  * This is only used for dm-raid456, caller already frozen sync_thread, hence
8935  * if rehsape is still in progress, io that is waiting for reshape can never be
8936  * done now, hence wake up and handle those IO.
8937  */
8938 static void raid5_prepare_suspend(struct mddev *mddev)
8939 {
8940 	struct r5conf *conf = mddev->private;
8941 
8942 	wake_up(&conf->wait_for_overlap);
8943 }
8944 
8945 static struct md_personality raid6_personality =
8946 {
8947 	.name		= "raid6",
8948 	.level		= 6,
8949 	.owner		= THIS_MODULE,
8950 	.make_request	= raid5_make_request,
8951 	.run		= raid5_run,
8952 	.start		= raid5_start,
8953 	.free		= raid5_free,
8954 	.status		= raid5_status,
8955 	.error_handler	= raid5_error,
8956 	.hot_add_disk	= raid5_add_disk,
8957 	.hot_remove_disk= raid5_remove_disk,
8958 	.spare_active	= raid5_spare_active,
8959 	.sync_request	= raid5_sync_request,
8960 	.resize		= raid5_resize,
8961 	.size		= raid5_size,
8962 	.check_reshape	= raid6_check_reshape,
8963 	.start_reshape  = raid5_start_reshape,
8964 	.finish_reshape = raid5_finish_reshape,
8965 	.quiesce	= raid5_quiesce,
8966 	.takeover	= raid6_takeover,
8967 	.change_consistency_policy = raid5_change_consistency_policy,
8968 	.prepare_suspend = raid5_prepare_suspend,
8969 };
8970 static struct md_personality raid5_personality =
8971 {
8972 	.name		= "raid5",
8973 	.level		= 5,
8974 	.owner		= THIS_MODULE,
8975 	.make_request	= raid5_make_request,
8976 	.run		= raid5_run,
8977 	.start		= raid5_start,
8978 	.free		= raid5_free,
8979 	.status		= raid5_status,
8980 	.error_handler	= raid5_error,
8981 	.hot_add_disk	= raid5_add_disk,
8982 	.hot_remove_disk= raid5_remove_disk,
8983 	.spare_active	= raid5_spare_active,
8984 	.sync_request	= raid5_sync_request,
8985 	.resize		= raid5_resize,
8986 	.size		= raid5_size,
8987 	.check_reshape	= raid5_check_reshape,
8988 	.start_reshape  = raid5_start_reshape,
8989 	.finish_reshape = raid5_finish_reshape,
8990 	.quiesce	= raid5_quiesce,
8991 	.takeover	= raid5_takeover,
8992 	.change_consistency_policy = raid5_change_consistency_policy,
8993 	.prepare_suspend = raid5_prepare_suspend,
8994 };
8995 
8996 static struct md_personality raid4_personality =
8997 {
8998 	.name		= "raid4",
8999 	.level		= 4,
9000 	.owner		= THIS_MODULE,
9001 	.make_request	= raid5_make_request,
9002 	.run		= raid5_run,
9003 	.start		= raid5_start,
9004 	.free		= raid5_free,
9005 	.status		= raid5_status,
9006 	.error_handler	= raid5_error,
9007 	.hot_add_disk	= raid5_add_disk,
9008 	.hot_remove_disk= raid5_remove_disk,
9009 	.spare_active	= raid5_spare_active,
9010 	.sync_request	= raid5_sync_request,
9011 	.resize		= raid5_resize,
9012 	.size		= raid5_size,
9013 	.check_reshape	= raid5_check_reshape,
9014 	.start_reshape  = raid5_start_reshape,
9015 	.finish_reshape = raid5_finish_reshape,
9016 	.quiesce	= raid5_quiesce,
9017 	.takeover	= raid4_takeover,
9018 	.change_consistency_policy = raid5_change_consistency_policy,
9019 	.prepare_suspend = raid5_prepare_suspend,
9020 };
9021 
9022 static int __init raid5_init(void)
9023 {
9024 	int ret;
9025 
9026 	raid5_wq = alloc_workqueue("raid5wq",
9027 		WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
9028 	if (!raid5_wq)
9029 		return -ENOMEM;
9030 
9031 	ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
9032 				      "md/raid5:prepare",
9033 				      raid456_cpu_up_prepare,
9034 				      raid456_cpu_dead);
9035 	if (ret) {
9036 		destroy_workqueue(raid5_wq);
9037 		return ret;
9038 	}
9039 	register_md_personality(&raid6_personality);
9040 	register_md_personality(&raid5_personality);
9041 	register_md_personality(&raid4_personality);
9042 	return 0;
9043 }
9044 
9045 static void raid5_exit(void)
9046 {
9047 	unregister_md_personality(&raid6_personality);
9048 	unregister_md_personality(&raid5_personality);
9049 	unregister_md_personality(&raid4_personality);
9050 	cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
9051 	destroy_workqueue(raid5_wq);
9052 }
9053 
9054 module_init(raid5_init);
9055 module_exit(raid5_exit);
9056 MODULE_LICENSE("GPL");
9057 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
9058 MODULE_ALIAS("md-personality-4"); /* RAID5 */
9059 MODULE_ALIAS("md-raid5");
9060 MODULE_ALIAS("md-raid4");
9061 MODULE_ALIAS("md-level-5");
9062 MODULE_ALIAS("md-level-4");
9063 MODULE_ALIAS("md-personality-8"); /* RAID6 */
9064 MODULE_ALIAS("md-raid6");
9065 MODULE_ALIAS("md-level-6");
9066 
9067 /* This used to be two separate modules, they were: */
9068 MODULE_ALIAS("raid5");
9069 MODULE_ALIAS("raid6");
9070