xref: /openbmc/linux/drivers/md/raid5.c (revision 5d7800d9)
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/delay.h>
40 #include <linux/kthread.h>
41 #include <linux/raid/pq.h>
42 #include <linux/async_tx.h>
43 #include <linux/module.h>
44 #include <linux/async.h>
45 #include <linux/seq_file.h>
46 #include <linux/cpu.h>
47 #include <linux/slab.h>
48 #include <linux/ratelimit.h>
49 #include <linux/nodemask.h>
50 
51 #include <trace/events/block.h>
52 #include <linux/list_sort.h>
53 
54 #include "md.h"
55 #include "raid5.h"
56 #include "raid0.h"
57 #include "md-bitmap.h"
58 #include "raid5-log.h"
59 
60 #define UNSUPPORTED_MDDEV_FLAGS	(1L << MD_FAILFAST_SUPPORTED)
61 
62 #define cpu_to_group(cpu) cpu_to_node(cpu)
63 #define ANY_GROUP NUMA_NO_NODE
64 
65 #define RAID5_MAX_REQ_STRIPES 256
66 
67 static bool devices_handle_discard_safely = false;
68 module_param(devices_handle_discard_safely, bool, 0644);
69 MODULE_PARM_DESC(devices_handle_discard_safely,
70 		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
71 static struct workqueue_struct *raid5_wq;
72 
73 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
74 {
75 	int hash = (sect >> RAID5_STRIPE_SHIFT(conf)) & HASH_MASK;
76 	return &conf->stripe_hashtbl[hash];
77 }
78 
79 static inline int stripe_hash_locks_hash(struct r5conf *conf, sector_t sect)
80 {
81 	return (sect >> RAID5_STRIPE_SHIFT(conf)) & STRIPE_HASH_LOCKS_MASK;
82 }
83 
84 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
85 	__acquires(&conf->device_lock)
86 {
87 	spin_lock_irq(conf->hash_locks + hash);
88 	spin_lock(&conf->device_lock);
89 }
90 
91 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
92 	__releases(&conf->device_lock)
93 {
94 	spin_unlock(&conf->device_lock);
95 	spin_unlock_irq(conf->hash_locks + hash);
96 }
97 
98 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
99 	__acquires(&conf->device_lock)
100 {
101 	int i;
102 	spin_lock_irq(conf->hash_locks);
103 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
104 		spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
105 	spin_lock(&conf->device_lock);
106 }
107 
108 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
109 	__releases(&conf->device_lock)
110 {
111 	int i;
112 	spin_unlock(&conf->device_lock);
113 	for (i = NR_STRIPE_HASH_LOCKS - 1; i; i--)
114 		spin_unlock(conf->hash_locks + i);
115 	spin_unlock_irq(conf->hash_locks);
116 }
117 
118 /* Find first data disk in a raid6 stripe */
119 static inline int raid6_d0(struct stripe_head *sh)
120 {
121 	if (sh->ddf_layout)
122 		/* ddf always start from first device */
123 		return 0;
124 	/* md starts just after Q block */
125 	if (sh->qd_idx == sh->disks - 1)
126 		return 0;
127 	else
128 		return sh->qd_idx + 1;
129 }
130 static inline int raid6_next_disk(int disk, int raid_disks)
131 {
132 	disk++;
133 	return (disk < raid_disks) ? disk : 0;
134 }
135 
136 /* When walking through the disks in a raid5, starting at raid6_d0,
137  * We need to map each disk to a 'slot', where the data disks are slot
138  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
139  * is raid_disks-1.  This help does that mapping.
140  */
141 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
142 			     int *count, int syndrome_disks)
143 {
144 	int slot = *count;
145 
146 	if (sh->ddf_layout)
147 		(*count)++;
148 	if (idx == sh->pd_idx)
149 		return syndrome_disks;
150 	if (idx == sh->qd_idx)
151 		return syndrome_disks + 1;
152 	if (!sh->ddf_layout)
153 		(*count)++;
154 	return slot;
155 }
156 
157 static void print_raid5_conf (struct r5conf *conf);
158 
159 static int stripe_operations_active(struct stripe_head *sh)
160 {
161 	return sh->check_state || sh->reconstruct_state ||
162 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
163 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
164 }
165 
166 static bool stripe_is_lowprio(struct stripe_head *sh)
167 {
168 	return (test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state) ||
169 		test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) &&
170 	       !test_bit(STRIPE_R5C_CACHING, &sh->state);
171 }
172 
173 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
174 	__must_hold(&sh->raid_conf->device_lock)
175 {
176 	struct r5conf *conf = sh->raid_conf;
177 	struct r5worker_group *group;
178 	int thread_cnt;
179 	int i, cpu = sh->cpu;
180 
181 	if (!cpu_online(cpu)) {
182 		cpu = cpumask_any(cpu_online_mask);
183 		sh->cpu = cpu;
184 	}
185 
186 	if (list_empty(&sh->lru)) {
187 		struct r5worker_group *group;
188 		group = conf->worker_groups + cpu_to_group(cpu);
189 		if (stripe_is_lowprio(sh))
190 			list_add_tail(&sh->lru, &group->loprio_list);
191 		else
192 			list_add_tail(&sh->lru, &group->handle_list);
193 		group->stripes_cnt++;
194 		sh->group = group;
195 	}
196 
197 	if (conf->worker_cnt_per_group == 0) {
198 		md_wakeup_thread(conf->mddev->thread);
199 		return;
200 	}
201 
202 	group = conf->worker_groups + cpu_to_group(sh->cpu);
203 
204 	group->workers[0].working = true;
205 	/* at least one worker should run to avoid race */
206 	queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
207 
208 	thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
209 	/* wakeup more workers */
210 	for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
211 		if (group->workers[i].working == false) {
212 			group->workers[i].working = true;
213 			queue_work_on(sh->cpu, raid5_wq,
214 				      &group->workers[i].work);
215 			thread_cnt--;
216 		}
217 	}
218 }
219 
220 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
221 			      struct list_head *temp_inactive_list)
222 	__must_hold(&conf->device_lock)
223 {
224 	int i;
225 	int injournal = 0;	/* number of date pages with R5_InJournal */
226 
227 	BUG_ON(!list_empty(&sh->lru));
228 	BUG_ON(atomic_read(&conf->active_stripes)==0);
229 
230 	if (r5c_is_writeback(conf->log))
231 		for (i = sh->disks; i--; )
232 			if (test_bit(R5_InJournal, &sh->dev[i].flags))
233 				injournal++;
234 	/*
235 	 * In the following cases, the stripe cannot be released to cached
236 	 * lists. Therefore, we make the stripe write out and set
237 	 * STRIPE_HANDLE:
238 	 *   1. when quiesce in r5c write back;
239 	 *   2. when resync is requested fot the stripe.
240 	 */
241 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) ||
242 	    (conf->quiesce && r5c_is_writeback(conf->log) &&
243 	     !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0)) {
244 		if (test_bit(STRIPE_R5C_CACHING, &sh->state))
245 			r5c_make_stripe_write_out(sh);
246 		set_bit(STRIPE_HANDLE, &sh->state);
247 	}
248 
249 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
250 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
251 		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
252 			list_add_tail(&sh->lru, &conf->delayed_list);
253 		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
254 			   sh->bm_seq - conf->seq_write > 0)
255 			list_add_tail(&sh->lru, &conf->bitmap_list);
256 		else {
257 			clear_bit(STRIPE_DELAYED, &sh->state);
258 			clear_bit(STRIPE_BIT_DELAY, &sh->state);
259 			if (conf->worker_cnt_per_group == 0) {
260 				if (stripe_is_lowprio(sh))
261 					list_add_tail(&sh->lru,
262 							&conf->loprio_list);
263 				else
264 					list_add_tail(&sh->lru,
265 							&conf->handle_list);
266 			} else {
267 				raid5_wakeup_stripe_thread(sh);
268 				return;
269 			}
270 		}
271 		md_wakeup_thread(conf->mddev->thread);
272 	} else {
273 		BUG_ON(stripe_operations_active(sh));
274 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
275 			if (atomic_dec_return(&conf->preread_active_stripes)
276 			    < IO_THRESHOLD)
277 				md_wakeup_thread(conf->mddev->thread);
278 		atomic_dec(&conf->active_stripes);
279 		if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
280 			if (!r5c_is_writeback(conf->log))
281 				list_add_tail(&sh->lru, temp_inactive_list);
282 			else {
283 				WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
284 				if (injournal == 0)
285 					list_add_tail(&sh->lru, temp_inactive_list);
286 				else if (injournal == conf->raid_disks - conf->max_degraded) {
287 					/* full stripe */
288 					if (!test_and_set_bit(STRIPE_R5C_FULL_STRIPE, &sh->state))
289 						atomic_inc(&conf->r5c_cached_full_stripes);
290 					if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
291 						atomic_dec(&conf->r5c_cached_partial_stripes);
292 					list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
293 					r5c_check_cached_full_stripe(conf);
294 				} else
295 					/*
296 					 * STRIPE_R5C_PARTIAL_STRIPE is set in
297 					 * r5c_try_caching_write(). No need to
298 					 * set it again.
299 					 */
300 					list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
301 			}
302 		}
303 	}
304 }
305 
306 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
307 			     struct list_head *temp_inactive_list)
308 	__must_hold(&conf->device_lock)
309 {
310 	if (atomic_dec_and_test(&sh->count))
311 		do_release_stripe(conf, sh, temp_inactive_list);
312 }
313 
314 /*
315  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
316  *
317  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
318  * given time. Adding stripes only takes device lock, while deleting stripes
319  * only takes hash lock.
320  */
321 static void release_inactive_stripe_list(struct r5conf *conf,
322 					 struct list_head *temp_inactive_list,
323 					 int hash)
324 {
325 	int size;
326 	bool do_wakeup = false;
327 	unsigned long flags;
328 
329 	if (hash == NR_STRIPE_HASH_LOCKS) {
330 		size = NR_STRIPE_HASH_LOCKS;
331 		hash = NR_STRIPE_HASH_LOCKS - 1;
332 	} else
333 		size = 1;
334 	while (size) {
335 		struct list_head *list = &temp_inactive_list[size - 1];
336 
337 		/*
338 		 * We don't hold any lock here yet, raid5_get_active_stripe() might
339 		 * remove stripes from the list
340 		 */
341 		if (!list_empty_careful(list)) {
342 			spin_lock_irqsave(conf->hash_locks + hash, flags);
343 			if (list_empty(conf->inactive_list + hash) &&
344 			    !list_empty(list))
345 				atomic_dec(&conf->empty_inactive_list_nr);
346 			list_splice_tail_init(list, conf->inactive_list + hash);
347 			do_wakeup = true;
348 			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
349 		}
350 		size--;
351 		hash--;
352 	}
353 
354 	if (do_wakeup) {
355 		wake_up(&conf->wait_for_stripe);
356 		if (atomic_read(&conf->active_stripes) == 0)
357 			wake_up(&conf->wait_for_quiescent);
358 		if (conf->retry_read_aligned)
359 			md_wakeup_thread(conf->mddev->thread);
360 	}
361 }
362 
363 static int release_stripe_list(struct r5conf *conf,
364 			       struct list_head *temp_inactive_list)
365 	__must_hold(&conf->device_lock)
366 {
367 	struct stripe_head *sh, *t;
368 	int count = 0;
369 	struct llist_node *head;
370 
371 	head = llist_del_all(&conf->released_stripes);
372 	head = llist_reverse_order(head);
373 	llist_for_each_entry_safe(sh, t, head, release_list) {
374 		int hash;
375 
376 		/* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
377 		smp_mb();
378 		clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
379 		/*
380 		 * Don't worry the bit is set here, because if the bit is set
381 		 * again, the count is always > 1. This is true for
382 		 * STRIPE_ON_UNPLUG_LIST bit too.
383 		 */
384 		hash = sh->hash_lock_index;
385 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
386 		count++;
387 	}
388 
389 	return count;
390 }
391 
392 void raid5_release_stripe(struct stripe_head *sh)
393 {
394 	struct r5conf *conf = sh->raid_conf;
395 	unsigned long flags;
396 	struct list_head list;
397 	int hash;
398 	bool wakeup;
399 
400 	/* Avoid release_list until the last reference.
401 	 */
402 	if (atomic_add_unless(&sh->count, -1, 1))
403 		return;
404 
405 	if (unlikely(!conf->mddev->thread) ||
406 		test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
407 		goto slow_path;
408 	wakeup = llist_add(&sh->release_list, &conf->released_stripes);
409 	if (wakeup)
410 		md_wakeup_thread(conf->mddev->thread);
411 	return;
412 slow_path:
413 	/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
414 	if (atomic_dec_and_lock_irqsave(&sh->count, &conf->device_lock, flags)) {
415 		INIT_LIST_HEAD(&list);
416 		hash = sh->hash_lock_index;
417 		do_release_stripe(conf, sh, &list);
418 		spin_unlock_irqrestore(&conf->device_lock, flags);
419 		release_inactive_stripe_list(conf, &list, hash);
420 	}
421 }
422 
423 static inline void remove_hash(struct stripe_head *sh)
424 {
425 	pr_debug("remove_hash(), stripe %llu\n",
426 		(unsigned long long)sh->sector);
427 
428 	hlist_del_init(&sh->hash);
429 }
430 
431 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
432 {
433 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
434 
435 	pr_debug("insert_hash(), stripe %llu\n",
436 		(unsigned long long)sh->sector);
437 
438 	hlist_add_head(&sh->hash, hp);
439 }
440 
441 /* find an idle stripe, make sure it is unhashed, and return it. */
442 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
443 {
444 	struct stripe_head *sh = NULL;
445 	struct list_head *first;
446 
447 	if (list_empty(conf->inactive_list + hash))
448 		goto out;
449 	first = (conf->inactive_list + hash)->next;
450 	sh = list_entry(first, struct stripe_head, lru);
451 	list_del_init(first);
452 	remove_hash(sh);
453 	atomic_inc(&conf->active_stripes);
454 	BUG_ON(hash != sh->hash_lock_index);
455 	if (list_empty(conf->inactive_list + hash))
456 		atomic_inc(&conf->empty_inactive_list_nr);
457 out:
458 	return sh;
459 }
460 
461 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
462 static void free_stripe_pages(struct stripe_head *sh)
463 {
464 	int i;
465 	struct page *p;
466 
467 	/* Have not allocate page pool */
468 	if (!sh->pages)
469 		return;
470 
471 	for (i = 0; i < sh->nr_pages; i++) {
472 		p = sh->pages[i];
473 		if (p)
474 			put_page(p);
475 		sh->pages[i] = NULL;
476 	}
477 }
478 
479 static int alloc_stripe_pages(struct stripe_head *sh, gfp_t gfp)
480 {
481 	int i;
482 	struct page *p;
483 
484 	for (i = 0; i < sh->nr_pages; i++) {
485 		/* The page have allocated. */
486 		if (sh->pages[i])
487 			continue;
488 
489 		p = alloc_page(gfp);
490 		if (!p) {
491 			free_stripe_pages(sh);
492 			return -ENOMEM;
493 		}
494 		sh->pages[i] = p;
495 	}
496 	return 0;
497 }
498 
499 static int
500 init_stripe_shared_pages(struct stripe_head *sh, struct r5conf *conf, int disks)
501 {
502 	int nr_pages, cnt;
503 
504 	if (sh->pages)
505 		return 0;
506 
507 	/* Each of the sh->dev[i] need one conf->stripe_size */
508 	cnt = PAGE_SIZE / conf->stripe_size;
509 	nr_pages = (disks + cnt - 1) / cnt;
510 
511 	sh->pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
512 	if (!sh->pages)
513 		return -ENOMEM;
514 	sh->nr_pages = nr_pages;
515 	sh->stripes_per_page = cnt;
516 	return 0;
517 }
518 #endif
519 
520 static void shrink_buffers(struct stripe_head *sh)
521 {
522 	int i;
523 	int num = sh->raid_conf->pool_size;
524 
525 #if PAGE_SIZE == DEFAULT_STRIPE_SIZE
526 	for (i = 0; i < num ; i++) {
527 		struct page *p;
528 
529 		WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
530 		p = sh->dev[i].page;
531 		if (!p)
532 			continue;
533 		sh->dev[i].page = NULL;
534 		put_page(p);
535 	}
536 #else
537 	for (i = 0; i < num; i++)
538 		sh->dev[i].page = NULL;
539 	free_stripe_pages(sh); /* Free pages */
540 #endif
541 }
542 
543 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
544 {
545 	int i;
546 	int num = sh->raid_conf->pool_size;
547 
548 #if PAGE_SIZE == DEFAULT_STRIPE_SIZE
549 	for (i = 0; i < num; i++) {
550 		struct page *page;
551 
552 		if (!(page = alloc_page(gfp))) {
553 			return 1;
554 		}
555 		sh->dev[i].page = page;
556 		sh->dev[i].orig_page = page;
557 		sh->dev[i].offset = 0;
558 	}
559 #else
560 	if (alloc_stripe_pages(sh, gfp))
561 		return -ENOMEM;
562 
563 	for (i = 0; i < num; i++) {
564 		sh->dev[i].page = raid5_get_dev_page(sh, i);
565 		sh->dev[i].orig_page = sh->dev[i].page;
566 		sh->dev[i].offset = raid5_get_page_offset(sh, i);
567 	}
568 #endif
569 	return 0;
570 }
571 
572 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
573 			    struct stripe_head *sh);
574 
575 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
576 {
577 	struct r5conf *conf = sh->raid_conf;
578 	int i, seq;
579 
580 	BUG_ON(atomic_read(&sh->count) != 0);
581 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
582 	BUG_ON(stripe_operations_active(sh));
583 	BUG_ON(sh->batch_head);
584 
585 	pr_debug("init_stripe called, stripe %llu\n",
586 		(unsigned long long)sector);
587 retry:
588 	seq = read_seqcount_begin(&conf->gen_lock);
589 	sh->generation = conf->generation - previous;
590 	sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
591 	sh->sector = sector;
592 	stripe_set_idx(sector, conf, previous, sh);
593 	sh->state = 0;
594 
595 	for (i = sh->disks; i--; ) {
596 		struct r5dev *dev = &sh->dev[i];
597 
598 		if (dev->toread || dev->read || dev->towrite || dev->written ||
599 		    test_bit(R5_LOCKED, &dev->flags)) {
600 			pr_err("sector=%llx i=%d %p %p %p %p %d\n",
601 			       (unsigned long long)sh->sector, i, dev->toread,
602 			       dev->read, dev->towrite, dev->written,
603 			       test_bit(R5_LOCKED, &dev->flags));
604 			WARN_ON(1);
605 		}
606 		dev->flags = 0;
607 		dev->sector = raid5_compute_blocknr(sh, i, previous);
608 	}
609 	if (read_seqcount_retry(&conf->gen_lock, seq))
610 		goto retry;
611 	sh->overwrite_disks = 0;
612 	insert_hash(conf, sh);
613 	sh->cpu = smp_processor_id();
614 	set_bit(STRIPE_BATCH_READY, &sh->state);
615 }
616 
617 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
618 					 short generation)
619 {
620 	struct stripe_head *sh;
621 
622 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
623 	hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
624 		if (sh->sector == sector && sh->generation == generation)
625 			return sh;
626 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
627 	return NULL;
628 }
629 
630 static struct stripe_head *find_get_stripe(struct r5conf *conf,
631 		sector_t sector, short generation, int hash)
632 {
633 	int inc_empty_inactive_list_flag;
634 	struct stripe_head *sh;
635 
636 	sh = __find_stripe(conf, sector, generation);
637 	if (!sh)
638 		return NULL;
639 
640 	if (atomic_inc_not_zero(&sh->count))
641 		return sh;
642 
643 	/*
644 	 * Slow path. The reference count is zero which means the stripe must
645 	 * be on a list (sh->lru). Must remove the stripe from the list that
646 	 * references it with the device_lock held.
647 	 */
648 
649 	spin_lock(&conf->device_lock);
650 	if (!atomic_read(&sh->count)) {
651 		if (!test_bit(STRIPE_HANDLE, &sh->state))
652 			atomic_inc(&conf->active_stripes);
653 		BUG_ON(list_empty(&sh->lru) &&
654 		       !test_bit(STRIPE_EXPANDING, &sh->state));
655 		inc_empty_inactive_list_flag = 0;
656 		if (!list_empty(conf->inactive_list + hash))
657 			inc_empty_inactive_list_flag = 1;
658 		list_del_init(&sh->lru);
659 		if (list_empty(conf->inactive_list + hash) &&
660 		    inc_empty_inactive_list_flag)
661 			atomic_inc(&conf->empty_inactive_list_nr);
662 		if (sh->group) {
663 			sh->group->stripes_cnt--;
664 			sh->group = NULL;
665 		}
666 	}
667 	atomic_inc(&sh->count);
668 	spin_unlock(&conf->device_lock);
669 
670 	return sh;
671 }
672 
673 /*
674  * Need to check if array has failed when deciding whether to:
675  *  - start an array
676  *  - remove non-faulty devices
677  *  - add a spare
678  *  - allow a reshape
679  * This determination is simple when no reshape is happening.
680  * However if there is a reshape, we need to carefully check
681  * both the before and after sections.
682  * This is because some failed devices may only affect one
683  * of the two sections, and some non-in_sync devices may
684  * be insync in the section most affected by failed devices.
685  *
686  * Most calls to this function hold &conf->device_lock. Calls
687  * in raid5_run() do not require the lock as no other threads
688  * have been started yet.
689  */
690 int raid5_calc_degraded(struct r5conf *conf)
691 {
692 	int degraded, degraded2;
693 	int i;
694 
695 	rcu_read_lock();
696 	degraded = 0;
697 	for (i = 0; i < conf->previous_raid_disks; i++) {
698 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
699 		if (rdev && test_bit(Faulty, &rdev->flags))
700 			rdev = rcu_dereference(conf->disks[i].replacement);
701 		if (!rdev || test_bit(Faulty, &rdev->flags))
702 			degraded++;
703 		else if (test_bit(In_sync, &rdev->flags))
704 			;
705 		else
706 			/* not in-sync or faulty.
707 			 * If the reshape increases the number of devices,
708 			 * this is being recovered by the reshape, so
709 			 * this 'previous' section is not in_sync.
710 			 * If the number of devices is being reduced however,
711 			 * the device can only be part of the array if
712 			 * we are reverting a reshape, so this section will
713 			 * be in-sync.
714 			 */
715 			if (conf->raid_disks >= conf->previous_raid_disks)
716 				degraded++;
717 	}
718 	rcu_read_unlock();
719 	if (conf->raid_disks == conf->previous_raid_disks)
720 		return degraded;
721 	rcu_read_lock();
722 	degraded2 = 0;
723 	for (i = 0; i < conf->raid_disks; i++) {
724 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
725 		if (rdev && test_bit(Faulty, &rdev->flags))
726 			rdev = rcu_dereference(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 	rcu_read_unlock();
741 	if (degraded2 > degraded)
742 		return degraded2;
743 	return degraded;
744 }
745 
746 static bool has_failed(struct r5conf *conf)
747 {
748 	int degraded = conf->mddev->degraded;
749 
750 	if (test_bit(MD_BROKEN, &conf->mddev->flags))
751 		return true;
752 
753 	if (conf->mddev->reshape_position != MaxSector)
754 		degraded = raid5_calc_degraded(conf);
755 
756 	return degraded > conf->max_degraded;
757 }
758 
759 enum stripe_result {
760 	STRIPE_SUCCESS = 0,
761 	STRIPE_RETRY,
762 	STRIPE_SCHEDULE_AND_RETRY,
763 	STRIPE_FAIL,
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 		wait_event_lock_irq(conf->wait_for_stripe,
858 				    is_inactive_blocked(conf, hash),
859 				    *(conf->hash_locks + hash));
860 		clear_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
861 	}
862 
863 	spin_unlock_irq(conf->hash_locks + hash);
864 	return sh;
865 }
866 
867 static bool is_full_stripe_write(struct stripe_head *sh)
868 {
869 	BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
870 	return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
871 }
872 
873 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
874 		__acquires(&sh1->stripe_lock)
875 		__acquires(&sh2->stripe_lock)
876 {
877 	if (sh1 > sh2) {
878 		spin_lock_irq(&sh2->stripe_lock);
879 		spin_lock_nested(&sh1->stripe_lock, 1);
880 	} else {
881 		spin_lock_irq(&sh1->stripe_lock);
882 		spin_lock_nested(&sh2->stripe_lock, 1);
883 	}
884 }
885 
886 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
887 		__releases(&sh1->stripe_lock)
888 		__releases(&sh2->stripe_lock)
889 {
890 	spin_unlock(&sh1->stripe_lock);
891 	spin_unlock_irq(&sh2->stripe_lock);
892 }
893 
894 /* Only freshly new full stripe normal write stripe can be added to a batch list */
895 static bool stripe_can_batch(struct stripe_head *sh)
896 {
897 	struct r5conf *conf = sh->raid_conf;
898 
899 	if (raid5_has_log(conf) || raid5_has_ppl(conf))
900 		return false;
901 	return test_bit(STRIPE_BATCH_READY, &sh->state) &&
902 		!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
903 		is_full_stripe_write(sh);
904 }
905 
906 /* we only do back search */
907 static void stripe_add_to_batch_list(struct r5conf *conf,
908 		struct stripe_head *sh, struct stripe_head *last_sh)
909 {
910 	struct stripe_head *head;
911 	sector_t head_sector, tmp_sec;
912 	int hash;
913 	int dd_idx;
914 
915 	/* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
916 	tmp_sec = sh->sector;
917 	if (!sector_div(tmp_sec, conf->chunk_sectors))
918 		return;
919 	head_sector = sh->sector - RAID5_STRIPE_SECTORS(conf);
920 
921 	if (last_sh && head_sector == last_sh->sector) {
922 		head = last_sh;
923 		atomic_inc(&head->count);
924 	} else {
925 		hash = stripe_hash_locks_hash(conf, head_sector);
926 		spin_lock_irq(conf->hash_locks + hash);
927 		head = find_get_stripe(conf, head_sector, conf->generation,
928 				       hash);
929 		spin_unlock_irq(conf->hash_locks + hash);
930 		if (!head)
931 			return;
932 		if (!stripe_can_batch(head))
933 			goto out;
934 	}
935 
936 	lock_two_stripes(head, sh);
937 	/* clear_batch_ready clear the flag */
938 	if (!stripe_can_batch(head) || !stripe_can_batch(sh))
939 		goto unlock_out;
940 
941 	if (sh->batch_head)
942 		goto unlock_out;
943 
944 	dd_idx = 0;
945 	while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
946 		dd_idx++;
947 	if (head->dev[dd_idx].towrite->bi_opf != sh->dev[dd_idx].towrite->bi_opf ||
948 	    bio_op(head->dev[dd_idx].towrite) != bio_op(sh->dev[dd_idx].towrite))
949 		goto unlock_out;
950 
951 	if (head->batch_head) {
952 		spin_lock(&head->batch_head->batch_lock);
953 		/* This batch list is already running */
954 		if (!stripe_can_batch(head)) {
955 			spin_unlock(&head->batch_head->batch_lock);
956 			goto unlock_out;
957 		}
958 		/*
959 		 * We must assign batch_head of this stripe within the
960 		 * batch_lock, otherwise clear_batch_ready of batch head
961 		 * stripe could clear BATCH_READY bit of this stripe and
962 		 * this stripe->batch_head doesn't get assigned, which
963 		 * could confuse clear_batch_ready for this stripe
964 		 */
965 		sh->batch_head = head->batch_head;
966 
967 		/*
968 		 * at this point, head's BATCH_READY could be cleared, but we
969 		 * can still add the stripe to batch list
970 		 */
971 		list_add(&sh->batch_list, &head->batch_list);
972 		spin_unlock(&head->batch_head->batch_lock);
973 	} else {
974 		head->batch_head = head;
975 		sh->batch_head = head->batch_head;
976 		spin_lock(&head->batch_lock);
977 		list_add_tail(&sh->batch_list, &head->batch_list);
978 		spin_unlock(&head->batch_lock);
979 	}
980 
981 	if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
982 		if (atomic_dec_return(&conf->preread_active_stripes)
983 		    < IO_THRESHOLD)
984 			md_wakeup_thread(conf->mddev->thread);
985 
986 	if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
987 		int seq = sh->bm_seq;
988 		if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
989 		    sh->batch_head->bm_seq > seq)
990 			seq = sh->batch_head->bm_seq;
991 		set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
992 		sh->batch_head->bm_seq = seq;
993 	}
994 
995 	atomic_inc(&sh->count);
996 unlock_out:
997 	unlock_two_stripes(head, sh);
998 out:
999 	raid5_release_stripe(head);
1000 }
1001 
1002 /* Determine if 'data_offset' or 'new_data_offset' should be used
1003  * in this stripe_head.
1004  */
1005 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
1006 {
1007 	sector_t progress = conf->reshape_progress;
1008 	/* Need a memory barrier to make sure we see the value
1009 	 * of conf->generation, or ->data_offset that was set before
1010 	 * reshape_progress was updated.
1011 	 */
1012 	smp_rmb();
1013 	if (progress == MaxSector)
1014 		return 0;
1015 	if (sh->generation == conf->generation - 1)
1016 		return 0;
1017 	/* We are in a reshape, and this is a new-generation stripe,
1018 	 * so use new_data_offset.
1019 	 */
1020 	return 1;
1021 }
1022 
1023 static void dispatch_bio_list(struct bio_list *tmp)
1024 {
1025 	struct bio *bio;
1026 
1027 	while ((bio = bio_list_pop(tmp)))
1028 		submit_bio_noacct(bio);
1029 }
1030 
1031 static int cmp_stripe(void *priv, const struct list_head *a,
1032 		      const struct list_head *b)
1033 {
1034 	const struct r5pending_data *da = list_entry(a,
1035 				struct r5pending_data, sibling);
1036 	const struct r5pending_data *db = list_entry(b,
1037 				struct r5pending_data, sibling);
1038 	if (da->sector > db->sector)
1039 		return 1;
1040 	if (da->sector < db->sector)
1041 		return -1;
1042 	return 0;
1043 }
1044 
1045 static void dispatch_defer_bios(struct r5conf *conf, int target,
1046 				struct bio_list *list)
1047 {
1048 	struct r5pending_data *data;
1049 	struct list_head *first, *next = NULL;
1050 	int cnt = 0;
1051 
1052 	if (conf->pending_data_cnt == 0)
1053 		return;
1054 
1055 	list_sort(NULL, &conf->pending_list, cmp_stripe);
1056 
1057 	first = conf->pending_list.next;
1058 
1059 	/* temporarily move the head */
1060 	if (conf->next_pending_data)
1061 		list_move_tail(&conf->pending_list,
1062 				&conf->next_pending_data->sibling);
1063 
1064 	while (!list_empty(&conf->pending_list)) {
1065 		data = list_first_entry(&conf->pending_list,
1066 			struct r5pending_data, sibling);
1067 		if (&data->sibling == first)
1068 			first = data->sibling.next;
1069 		next = data->sibling.next;
1070 
1071 		bio_list_merge(list, &data->bios);
1072 		list_move(&data->sibling, &conf->free_list);
1073 		cnt++;
1074 		if (cnt >= target)
1075 			break;
1076 	}
1077 	conf->pending_data_cnt -= cnt;
1078 	BUG_ON(conf->pending_data_cnt < 0 || cnt < target);
1079 
1080 	if (next != &conf->pending_list)
1081 		conf->next_pending_data = list_entry(next,
1082 				struct r5pending_data, sibling);
1083 	else
1084 		conf->next_pending_data = NULL;
1085 	/* list isn't empty */
1086 	if (first != &conf->pending_list)
1087 		list_move_tail(&conf->pending_list, first);
1088 }
1089 
1090 static void flush_deferred_bios(struct r5conf *conf)
1091 {
1092 	struct bio_list tmp = BIO_EMPTY_LIST;
1093 
1094 	if (conf->pending_data_cnt == 0)
1095 		return;
1096 
1097 	spin_lock(&conf->pending_bios_lock);
1098 	dispatch_defer_bios(conf, conf->pending_data_cnt, &tmp);
1099 	BUG_ON(conf->pending_data_cnt != 0);
1100 	spin_unlock(&conf->pending_bios_lock);
1101 
1102 	dispatch_bio_list(&tmp);
1103 }
1104 
1105 static void defer_issue_bios(struct r5conf *conf, sector_t sector,
1106 				struct bio_list *bios)
1107 {
1108 	struct bio_list tmp = BIO_EMPTY_LIST;
1109 	struct r5pending_data *ent;
1110 
1111 	spin_lock(&conf->pending_bios_lock);
1112 	ent = list_first_entry(&conf->free_list, struct r5pending_data,
1113 							sibling);
1114 	list_move_tail(&ent->sibling, &conf->pending_list);
1115 	ent->sector = sector;
1116 	bio_list_init(&ent->bios);
1117 	bio_list_merge(&ent->bios, bios);
1118 	conf->pending_data_cnt++;
1119 	if (conf->pending_data_cnt >= PENDING_IO_MAX)
1120 		dispatch_defer_bios(conf, PENDING_IO_ONE_FLUSH, &tmp);
1121 
1122 	spin_unlock(&conf->pending_bios_lock);
1123 
1124 	dispatch_bio_list(&tmp);
1125 }
1126 
1127 static void
1128 raid5_end_read_request(struct bio *bi);
1129 static void
1130 raid5_end_write_request(struct bio *bi);
1131 
1132 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
1133 {
1134 	struct r5conf *conf = sh->raid_conf;
1135 	int i, disks = sh->disks;
1136 	struct stripe_head *head_sh = sh;
1137 	struct bio_list pending_bios = BIO_EMPTY_LIST;
1138 	struct r5dev *dev;
1139 	bool should_defer;
1140 
1141 	might_sleep();
1142 
1143 	if (log_stripe(sh, s) == 0)
1144 		return;
1145 
1146 	should_defer = conf->batch_bio_dispatch && conf->group_cnt;
1147 
1148 	for (i = disks; i--; ) {
1149 		enum req_op op;
1150 		blk_opf_t op_flags = 0;
1151 		int replace_only = 0;
1152 		struct bio *bi, *rbi;
1153 		struct md_rdev *rdev, *rrdev = NULL;
1154 
1155 		sh = head_sh;
1156 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
1157 			op = REQ_OP_WRITE;
1158 			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
1159 				op_flags = REQ_FUA;
1160 			if (test_bit(R5_Discard, &sh->dev[i].flags))
1161 				op = REQ_OP_DISCARD;
1162 		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1163 			op = REQ_OP_READ;
1164 		else if (test_and_clear_bit(R5_WantReplace,
1165 					    &sh->dev[i].flags)) {
1166 			op = REQ_OP_WRITE;
1167 			replace_only = 1;
1168 		} else
1169 			continue;
1170 		if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
1171 			op_flags |= REQ_SYNC;
1172 
1173 again:
1174 		dev = &sh->dev[i];
1175 		bi = &dev->req;
1176 		rbi = &dev->rreq; /* For writing to replacement */
1177 
1178 		rcu_read_lock();
1179 		rrdev = rcu_dereference(conf->disks[i].replacement);
1180 		smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
1181 		rdev = rcu_dereference(conf->disks[i].rdev);
1182 		if (!rdev) {
1183 			rdev = rrdev;
1184 			rrdev = NULL;
1185 		}
1186 		if (op_is_write(op)) {
1187 			if (replace_only)
1188 				rdev = NULL;
1189 			if (rdev == rrdev)
1190 				/* We raced and saw duplicates */
1191 				rrdev = NULL;
1192 		} else {
1193 			if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
1194 				rdev = rrdev;
1195 			rrdev = NULL;
1196 		}
1197 
1198 		if (rdev && test_bit(Faulty, &rdev->flags))
1199 			rdev = NULL;
1200 		if (rdev)
1201 			atomic_inc(&rdev->nr_pending);
1202 		if (rrdev && test_bit(Faulty, &rrdev->flags))
1203 			rrdev = NULL;
1204 		if (rrdev)
1205 			atomic_inc(&rrdev->nr_pending);
1206 		rcu_read_unlock();
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 			sector_t first_bad;
1215 			int bad_sectors;
1216 			int bad = is_badblock(rdev, sh->sector, RAID5_STRIPE_SECTORS(conf),
1217 					      &first_bad, &bad_sectors);
1218 			if (!bad)
1219 				break;
1220 
1221 			if (bad < 0) {
1222 				set_bit(BlockedBadBlocks, &rdev->flags);
1223 				if (!conf->mddev->external &&
1224 				    conf->mddev->sb_flags) {
1225 					/* It is very unlikely, but we might
1226 					 * still need to write out the
1227 					 * bad block log - better give it
1228 					 * a chance*/
1229 					md_check_recovery(conf->mddev);
1230 				}
1231 				/*
1232 				 * Because md_wait_for_blocked_rdev
1233 				 * will dec nr_pending, we must
1234 				 * increment it first.
1235 				 */
1236 				atomic_inc(&rdev->nr_pending);
1237 				md_wait_for_blocked_rdev(rdev, conf->mddev);
1238 			} else {
1239 				/* Acknowledged bad block - skip the write */
1240 				rdev_dec_pending(rdev, conf->mddev);
1241 				rdev = NULL;
1242 			}
1243 		}
1244 
1245 		if (rdev) {
1246 			if (s->syncing || s->expanding || s->expanded
1247 			    || s->replacing)
1248 				md_sync_acct(rdev->bdev, RAID5_STRIPE_SECTORS(conf));
1249 
1250 			set_bit(STRIPE_IO_STARTED, &sh->state);
1251 
1252 			bio_init(bi, rdev->bdev, &dev->vec, 1, op | op_flags);
1253 			bi->bi_end_io = op_is_write(op)
1254 				? raid5_end_write_request
1255 				: raid5_end_read_request;
1256 			bi->bi_private = sh;
1257 
1258 			pr_debug("%s: for %llu schedule op %d on disc %d\n",
1259 				__func__, (unsigned long long)sh->sector,
1260 				bi->bi_opf, i);
1261 			atomic_inc(&sh->count);
1262 			if (sh != head_sh)
1263 				atomic_inc(&head_sh->count);
1264 			if (use_new_offset(conf, sh))
1265 				bi->bi_iter.bi_sector = (sh->sector
1266 						 + rdev->new_data_offset);
1267 			else
1268 				bi->bi_iter.bi_sector = (sh->sector
1269 						 + rdev->data_offset);
1270 			if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1271 				bi->bi_opf |= REQ_NOMERGE;
1272 
1273 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1274 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1275 
1276 			if (!op_is_write(op) &&
1277 			    test_bit(R5_InJournal, &sh->dev[i].flags))
1278 				/*
1279 				 * issuing read for a page in journal, this
1280 				 * must be preparing for prexor in rmw; read
1281 				 * the data into orig_page
1282 				 */
1283 				sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
1284 			else
1285 				sh->dev[i].vec.bv_page = sh->dev[i].page;
1286 			bi->bi_vcnt = 1;
1287 			bi->bi_io_vec[0].bv_len = RAID5_STRIPE_SIZE(conf);
1288 			bi->bi_io_vec[0].bv_offset = sh->dev[i].offset;
1289 			bi->bi_iter.bi_size = RAID5_STRIPE_SIZE(conf);
1290 			/*
1291 			 * If this is discard request, set bi_vcnt 0. We don't
1292 			 * want to confuse SCSI because SCSI will replace payload
1293 			 */
1294 			if (op == REQ_OP_DISCARD)
1295 				bi->bi_vcnt = 0;
1296 			if (rrdev)
1297 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1298 
1299 			if (conf->mddev->gendisk)
1300 				trace_block_bio_remap(bi,
1301 						disk_devt(conf->mddev->gendisk),
1302 						sh->dev[i].sector);
1303 			if (should_defer && op_is_write(op))
1304 				bio_list_add(&pending_bios, bi);
1305 			else
1306 				submit_bio_noacct(bi);
1307 		}
1308 		if (rrdev) {
1309 			if (s->syncing || s->expanding || s->expanded
1310 			    || s->replacing)
1311 				md_sync_acct(rrdev->bdev, RAID5_STRIPE_SECTORS(conf));
1312 
1313 			set_bit(STRIPE_IO_STARTED, &sh->state);
1314 
1315 			bio_init(rbi, rrdev->bdev, &dev->rvec, 1, op | op_flags);
1316 			BUG_ON(!op_is_write(op));
1317 			rbi->bi_end_io = raid5_end_write_request;
1318 			rbi->bi_private = sh;
1319 
1320 			pr_debug("%s: for %llu schedule op %d on "
1321 				 "replacement disc %d\n",
1322 				__func__, (unsigned long long)sh->sector,
1323 				rbi->bi_opf, i);
1324 			atomic_inc(&sh->count);
1325 			if (sh != head_sh)
1326 				atomic_inc(&head_sh->count);
1327 			if (use_new_offset(conf, sh))
1328 				rbi->bi_iter.bi_sector = (sh->sector
1329 						  + rrdev->new_data_offset);
1330 			else
1331 				rbi->bi_iter.bi_sector = (sh->sector
1332 						  + rrdev->data_offset);
1333 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1334 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1335 			sh->dev[i].rvec.bv_page = sh->dev[i].page;
1336 			rbi->bi_vcnt = 1;
1337 			rbi->bi_io_vec[0].bv_len = RAID5_STRIPE_SIZE(conf);
1338 			rbi->bi_io_vec[0].bv_offset = sh->dev[i].offset;
1339 			rbi->bi_iter.bi_size = RAID5_STRIPE_SIZE(conf);
1340 			/*
1341 			 * If this is discard request, set bi_vcnt 0. We don't
1342 			 * want to confuse SCSI because SCSI will replace payload
1343 			 */
1344 			if (op == REQ_OP_DISCARD)
1345 				rbi->bi_vcnt = 0;
1346 			if (conf->mddev->gendisk)
1347 				trace_block_bio_remap(rbi,
1348 						disk_devt(conf->mddev->gendisk),
1349 						sh->dev[i].sector);
1350 			if (should_defer && op_is_write(op))
1351 				bio_list_add(&pending_bios, rbi);
1352 			else
1353 				submit_bio_noacct(rbi);
1354 		}
1355 		if (!rdev && !rrdev) {
1356 			if (op_is_write(op))
1357 				set_bit(STRIPE_DEGRADED, &sh->state);
1358 			pr_debug("skip op %d on disc %d for sector %llu\n",
1359 				bi->bi_opf, i, (unsigned long long)sh->sector);
1360 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
1361 			set_bit(STRIPE_HANDLE, &sh->state);
1362 		}
1363 
1364 		if (!head_sh->batch_head)
1365 			continue;
1366 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1367 				      batch_list);
1368 		if (sh != head_sh)
1369 			goto again;
1370 	}
1371 
1372 	if (should_defer && !bio_list_empty(&pending_bios))
1373 		defer_issue_bios(conf, head_sh->sector, &pending_bios);
1374 }
1375 
1376 static struct dma_async_tx_descriptor *
1377 async_copy_data(int frombio, struct bio *bio, struct page **page,
1378 	unsigned int poff, sector_t sector, struct dma_async_tx_descriptor *tx,
1379 	struct stripe_head *sh, int no_skipcopy)
1380 {
1381 	struct bio_vec bvl;
1382 	struct bvec_iter iter;
1383 	struct page *bio_page;
1384 	int page_offset;
1385 	struct async_submit_ctl submit;
1386 	enum async_tx_flags flags = 0;
1387 	struct r5conf *conf = sh->raid_conf;
1388 
1389 	if (bio->bi_iter.bi_sector >= sector)
1390 		page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1391 	else
1392 		page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1393 
1394 	if (frombio)
1395 		flags |= ASYNC_TX_FENCE;
1396 	init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1397 
1398 	bio_for_each_segment(bvl, bio, iter) {
1399 		int len = bvl.bv_len;
1400 		int clen;
1401 		int b_offset = 0;
1402 
1403 		if (page_offset < 0) {
1404 			b_offset = -page_offset;
1405 			page_offset += b_offset;
1406 			len -= b_offset;
1407 		}
1408 
1409 		if (len > 0 && page_offset + len > RAID5_STRIPE_SIZE(conf))
1410 			clen = RAID5_STRIPE_SIZE(conf) - page_offset;
1411 		else
1412 			clen = len;
1413 
1414 		if (clen > 0) {
1415 			b_offset += bvl.bv_offset;
1416 			bio_page = bvl.bv_page;
1417 			if (frombio) {
1418 				if (conf->skip_copy &&
1419 				    b_offset == 0 && page_offset == 0 &&
1420 				    clen == RAID5_STRIPE_SIZE(conf) &&
1421 				    !no_skipcopy)
1422 					*page = bio_page;
1423 				else
1424 					tx = async_memcpy(*page, bio_page, page_offset + poff,
1425 						  b_offset, clen, &submit);
1426 			} else
1427 				tx = async_memcpy(bio_page, *page, b_offset,
1428 						  page_offset + poff, clen, &submit);
1429 		}
1430 		/* chain the operations */
1431 		submit.depend_tx = tx;
1432 
1433 		if (clen < len) /* hit end of page */
1434 			break;
1435 		page_offset +=  len;
1436 	}
1437 
1438 	return tx;
1439 }
1440 
1441 static void ops_complete_biofill(void *stripe_head_ref)
1442 {
1443 	struct stripe_head *sh = stripe_head_ref;
1444 	int i;
1445 	struct r5conf *conf = sh->raid_conf;
1446 
1447 	pr_debug("%s: stripe %llu\n", __func__,
1448 		(unsigned long long)sh->sector);
1449 
1450 	/* clear completed biofills */
1451 	for (i = sh->disks; i--; ) {
1452 		struct r5dev *dev = &sh->dev[i];
1453 
1454 		/* acknowledge completion of a biofill operation */
1455 		/* and check if we need to reply to a read request,
1456 		 * new R5_Wantfill requests are held off until
1457 		 * !STRIPE_BIOFILL_RUN
1458 		 */
1459 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1460 			struct bio *rbi, *rbi2;
1461 
1462 			BUG_ON(!dev->read);
1463 			rbi = dev->read;
1464 			dev->read = NULL;
1465 			while (rbi && rbi->bi_iter.bi_sector <
1466 				dev->sector + RAID5_STRIPE_SECTORS(conf)) {
1467 				rbi2 = r5_next_bio(conf, rbi, dev->sector);
1468 				bio_endio(rbi);
1469 				rbi = rbi2;
1470 			}
1471 		}
1472 	}
1473 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1474 
1475 	set_bit(STRIPE_HANDLE, &sh->state);
1476 	raid5_release_stripe(sh);
1477 }
1478 
1479 static void ops_run_biofill(struct stripe_head *sh)
1480 {
1481 	struct dma_async_tx_descriptor *tx = NULL;
1482 	struct async_submit_ctl submit;
1483 	int i;
1484 	struct r5conf *conf = sh->raid_conf;
1485 
1486 	BUG_ON(sh->batch_head);
1487 	pr_debug("%s: stripe %llu\n", __func__,
1488 		(unsigned long long)sh->sector);
1489 
1490 	for (i = sh->disks; i--; ) {
1491 		struct r5dev *dev = &sh->dev[i];
1492 		if (test_bit(R5_Wantfill, &dev->flags)) {
1493 			struct bio *rbi;
1494 			spin_lock_irq(&sh->stripe_lock);
1495 			dev->read = rbi = dev->toread;
1496 			dev->toread = NULL;
1497 			spin_unlock_irq(&sh->stripe_lock);
1498 			while (rbi && rbi->bi_iter.bi_sector <
1499 				dev->sector + RAID5_STRIPE_SECTORS(conf)) {
1500 				tx = async_copy_data(0, rbi, &dev->page,
1501 						     dev->offset,
1502 						     dev->sector, tx, sh, 0);
1503 				rbi = r5_next_bio(conf, rbi, dev->sector);
1504 			}
1505 		}
1506 	}
1507 
1508 	atomic_inc(&sh->count);
1509 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1510 	async_trigger_callback(&submit);
1511 }
1512 
1513 static void mark_target_uptodate(struct stripe_head *sh, int target)
1514 {
1515 	struct r5dev *tgt;
1516 
1517 	if (target < 0)
1518 		return;
1519 
1520 	tgt = &sh->dev[target];
1521 	set_bit(R5_UPTODATE, &tgt->flags);
1522 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1523 	clear_bit(R5_Wantcompute, &tgt->flags);
1524 }
1525 
1526 static void ops_complete_compute(void *stripe_head_ref)
1527 {
1528 	struct stripe_head *sh = stripe_head_ref;
1529 
1530 	pr_debug("%s: stripe %llu\n", __func__,
1531 		(unsigned long long)sh->sector);
1532 
1533 	/* mark the computed target(s) as uptodate */
1534 	mark_target_uptodate(sh, sh->ops.target);
1535 	mark_target_uptodate(sh, sh->ops.target2);
1536 
1537 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1538 	if (sh->check_state == check_state_compute_run)
1539 		sh->check_state = check_state_compute_result;
1540 	set_bit(STRIPE_HANDLE, &sh->state);
1541 	raid5_release_stripe(sh);
1542 }
1543 
1544 /* return a pointer to the address conversion region of the scribble buffer */
1545 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1546 {
1547 	return percpu->scribble + i * percpu->scribble_obj_size;
1548 }
1549 
1550 /* return a pointer to the address conversion region of the scribble buffer */
1551 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1552 				 struct raid5_percpu *percpu, int i)
1553 {
1554 	return (void *) (to_addr_page(percpu, i) + sh->disks + 2);
1555 }
1556 
1557 /*
1558  * Return a pointer to record offset address.
1559  */
1560 static unsigned int *
1561 to_addr_offs(struct stripe_head *sh, struct raid5_percpu *percpu)
1562 {
1563 	return (unsigned int *) (to_addr_conv(sh, percpu, 0) + sh->disks + 2);
1564 }
1565 
1566 static struct dma_async_tx_descriptor *
1567 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1568 {
1569 	int disks = sh->disks;
1570 	struct page **xor_srcs = to_addr_page(percpu, 0);
1571 	unsigned int *off_srcs = to_addr_offs(sh, percpu);
1572 	int target = sh->ops.target;
1573 	struct r5dev *tgt = &sh->dev[target];
1574 	struct page *xor_dest = tgt->page;
1575 	unsigned int off_dest = tgt->offset;
1576 	int count = 0;
1577 	struct dma_async_tx_descriptor *tx;
1578 	struct async_submit_ctl submit;
1579 	int i;
1580 
1581 	BUG_ON(sh->batch_head);
1582 
1583 	pr_debug("%s: stripe %llu block: %d\n",
1584 		__func__, (unsigned long long)sh->sector, target);
1585 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1586 
1587 	for (i = disks; i--; ) {
1588 		if (i != target) {
1589 			off_srcs[count] = sh->dev[i].offset;
1590 			xor_srcs[count++] = sh->dev[i].page;
1591 		}
1592 	}
1593 
1594 	atomic_inc(&sh->count);
1595 
1596 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1597 			  ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1598 	if (unlikely(count == 1))
1599 		tx = async_memcpy(xor_dest, xor_srcs[0], off_dest, off_srcs[0],
1600 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1601 	else
1602 		tx = async_xor_offs(xor_dest, off_dest, xor_srcs, off_srcs, count,
1603 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1604 
1605 	return tx;
1606 }
1607 
1608 /* set_syndrome_sources - populate source buffers for gen_syndrome
1609  * @srcs - (struct page *) array of size sh->disks
1610  * @offs - (unsigned int) array of offset for each page
1611  * @sh - stripe_head to parse
1612  *
1613  * Populates srcs in proper layout order for the stripe and returns the
1614  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1615  * destination buffer is recorded in srcs[count] and the Q destination
1616  * is recorded in srcs[count+1]].
1617  */
1618 static int set_syndrome_sources(struct page **srcs,
1619 				unsigned int *offs,
1620 				struct stripe_head *sh,
1621 				int srctype)
1622 {
1623 	int disks = sh->disks;
1624 	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1625 	int d0_idx = raid6_d0(sh);
1626 	int count;
1627 	int i;
1628 
1629 	for (i = 0; i < disks; i++)
1630 		srcs[i] = NULL;
1631 
1632 	count = 0;
1633 	i = d0_idx;
1634 	do {
1635 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1636 		struct r5dev *dev = &sh->dev[i];
1637 
1638 		if (i == sh->qd_idx || i == sh->pd_idx ||
1639 		    (srctype == SYNDROME_SRC_ALL) ||
1640 		    (srctype == SYNDROME_SRC_WANT_DRAIN &&
1641 		     (test_bit(R5_Wantdrain, &dev->flags) ||
1642 		      test_bit(R5_InJournal, &dev->flags))) ||
1643 		    (srctype == SYNDROME_SRC_WRITTEN &&
1644 		     (dev->written ||
1645 		      test_bit(R5_InJournal, &dev->flags)))) {
1646 			if (test_bit(R5_InJournal, &dev->flags))
1647 				srcs[slot] = sh->dev[i].orig_page;
1648 			else
1649 				srcs[slot] = sh->dev[i].page;
1650 			/*
1651 			 * For R5_InJournal, PAGE_SIZE must be 4KB and will
1652 			 * not shared page. In that case, dev[i].offset
1653 			 * is 0.
1654 			 */
1655 			offs[slot] = sh->dev[i].offset;
1656 		}
1657 		i = raid6_next_disk(i, disks);
1658 	} while (i != d0_idx);
1659 
1660 	return syndrome_disks;
1661 }
1662 
1663 static struct dma_async_tx_descriptor *
1664 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1665 {
1666 	int disks = sh->disks;
1667 	struct page **blocks = to_addr_page(percpu, 0);
1668 	unsigned int *offs = to_addr_offs(sh, percpu);
1669 	int target;
1670 	int qd_idx = sh->qd_idx;
1671 	struct dma_async_tx_descriptor *tx;
1672 	struct async_submit_ctl submit;
1673 	struct r5dev *tgt;
1674 	struct page *dest;
1675 	unsigned int dest_off;
1676 	int i;
1677 	int count;
1678 
1679 	BUG_ON(sh->batch_head);
1680 	if (sh->ops.target < 0)
1681 		target = sh->ops.target2;
1682 	else if (sh->ops.target2 < 0)
1683 		target = sh->ops.target;
1684 	else
1685 		/* we should only have one valid target */
1686 		BUG();
1687 	BUG_ON(target < 0);
1688 	pr_debug("%s: stripe %llu block: %d\n",
1689 		__func__, (unsigned long long)sh->sector, target);
1690 
1691 	tgt = &sh->dev[target];
1692 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1693 	dest = tgt->page;
1694 	dest_off = tgt->offset;
1695 
1696 	atomic_inc(&sh->count);
1697 
1698 	if (target == qd_idx) {
1699 		count = set_syndrome_sources(blocks, offs, sh, SYNDROME_SRC_ALL);
1700 		blocks[count] = NULL; /* regenerating p is not necessary */
1701 		BUG_ON(blocks[count+1] != dest); /* q should already be set */
1702 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1703 				  ops_complete_compute, sh,
1704 				  to_addr_conv(sh, percpu, 0));
1705 		tx = async_gen_syndrome(blocks, offs, count+2,
1706 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1707 	} else {
1708 		/* Compute any data- or p-drive using XOR */
1709 		count = 0;
1710 		for (i = disks; i-- ; ) {
1711 			if (i == target || i == qd_idx)
1712 				continue;
1713 			offs[count] = sh->dev[i].offset;
1714 			blocks[count++] = sh->dev[i].page;
1715 		}
1716 
1717 		init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1718 				  NULL, ops_complete_compute, sh,
1719 				  to_addr_conv(sh, percpu, 0));
1720 		tx = async_xor_offs(dest, dest_off, blocks, offs, count,
1721 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1722 	}
1723 
1724 	return tx;
1725 }
1726 
1727 static struct dma_async_tx_descriptor *
1728 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1729 {
1730 	int i, count, disks = sh->disks;
1731 	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1732 	int d0_idx = raid6_d0(sh);
1733 	int faila = -1, failb = -1;
1734 	int target = sh->ops.target;
1735 	int target2 = sh->ops.target2;
1736 	struct r5dev *tgt = &sh->dev[target];
1737 	struct r5dev *tgt2 = &sh->dev[target2];
1738 	struct dma_async_tx_descriptor *tx;
1739 	struct page **blocks = to_addr_page(percpu, 0);
1740 	unsigned int *offs = to_addr_offs(sh, percpu);
1741 	struct async_submit_ctl submit;
1742 
1743 	BUG_ON(sh->batch_head);
1744 	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1745 		 __func__, (unsigned long long)sh->sector, target, target2);
1746 	BUG_ON(target < 0 || target2 < 0);
1747 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1748 	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1749 
1750 	/* we need to open-code set_syndrome_sources to handle the
1751 	 * slot number conversion for 'faila' and 'failb'
1752 	 */
1753 	for (i = 0; i < disks ; i++) {
1754 		offs[i] = 0;
1755 		blocks[i] = NULL;
1756 	}
1757 	count = 0;
1758 	i = d0_idx;
1759 	do {
1760 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1761 
1762 		offs[slot] = sh->dev[i].offset;
1763 		blocks[slot] = sh->dev[i].page;
1764 
1765 		if (i == target)
1766 			faila = slot;
1767 		if (i == target2)
1768 			failb = slot;
1769 		i = raid6_next_disk(i, disks);
1770 	} while (i != d0_idx);
1771 
1772 	BUG_ON(faila == failb);
1773 	if (failb < faila)
1774 		swap(faila, failb);
1775 	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1776 		 __func__, (unsigned long long)sh->sector, faila, failb);
1777 
1778 	atomic_inc(&sh->count);
1779 
1780 	if (failb == syndrome_disks+1) {
1781 		/* Q disk is one of the missing disks */
1782 		if (faila == syndrome_disks) {
1783 			/* Missing P+Q, just recompute */
1784 			init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1785 					  ops_complete_compute, sh,
1786 					  to_addr_conv(sh, percpu, 0));
1787 			return async_gen_syndrome(blocks, offs, syndrome_disks+2,
1788 						  RAID5_STRIPE_SIZE(sh->raid_conf),
1789 						  &submit);
1790 		} else {
1791 			struct page *dest;
1792 			unsigned int dest_off;
1793 			int data_target;
1794 			int qd_idx = sh->qd_idx;
1795 
1796 			/* Missing D+Q: recompute D from P, then recompute Q */
1797 			if (target == qd_idx)
1798 				data_target = target2;
1799 			else
1800 				data_target = target;
1801 
1802 			count = 0;
1803 			for (i = disks; i-- ; ) {
1804 				if (i == data_target || i == qd_idx)
1805 					continue;
1806 				offs[count] = sh->dev[i].offset;
1807 				blocks[count++] = sh->dev[i].page;
1808 			}
1809 			dest = sh->dev[data_target].page;
1810 			dest_off = sh->dev[data_target].offset;
1811 			init_async_submit(&submit,
1812 					  ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1813 					  NULL, NULL, NULL,
1814 					  to_addr_conv(sh, percpu, 0));
1815 			tx = async_xor_offs(dest, dest_off, blocks, offs, count,
1816 				       RAID5_STRIPE_SIZE(sh->raid_conf),
1817 				       &submit);
1818 
1819 			count = set_syndrome_sources(blocks, offs, sh, SYNDROME_SRC_ALL);
1820 			init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1821 					  ops_complete_compute, sh,
1822 					  to_addr_conv(sh, percpu, 0));
1823 			return async_gen_syndrome(blocks, offs, count+2,
1824 						  RAID5_STRIPE_SIZE(sh->raid_conf),
1825 						  &submit);
1826 		}
1827 	} else {
1828 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1829 				  ops_complete_compute, sh,
1830 				  to_addr_conv(sh, percpu, 0));
1831 		if (failb == syndrome_disks) {
1832 			/* We're missing D+P. */
1833 			return async_raid6_datap_recov(syndrome_disks+2,
1834 						RAID5_STRIPE_SIZE(sh->raid_conf),
1835 						faila,
1836 						blocks, offs, &submit);
1837 		} else {
1838 			/* We're missing D+D. */
1839 			return async_raid6_2data_recov(syndrome_disks+2,
1840 						RAID5_STRIPE_SIZE(sh->raid_conf),
1841 						faila, failb,
1842 						blocks, offs, &submit);
1843 		}
1844 	}
1845 }
1846 
1847 static void ops_complete_prexor(void *stripe_head_ref)
1848 {
1849 	struct stripe_head *sh = stripe_head_ref;
1850 
1851 	pr_debug("%s: stripe %llu\n", __func__,
1852 		(unsigned long long)sh->sector);
1853 
1854 	if (r5c_is_writeback(sh->raid_conf->log))
1855 		/*
1856 		 * raid5-cache write back uses orig_page during prexor.
1857 		 * After prexor, it is time to free orig_page
1858 		 */
1859 		r5c_release_extra_page(sh);
1860 }
1861 
1862 static struct dma_async_tx_descriptor *
1863 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1864 		struct dma_async_tx_descriptor *tx)
1865 {
1866 	int disks = sh->disks;
1867 	struct page **xor_srcs = to_addr_page(percpu, 0);
1868 	unsigned int *off_srcs = to_addr_offs(sh, percpu);
1869 	int count = 0, pd_idx = sh->pd_idx, i;
1870 	struct async_submit_ctl submit;
1871 
1872 	/* existing parity data subtracted */
1873 	unsigned int off_dest = off_srcs[count] = sh->dev[pd_idx].offset;
1874 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1875 
1876 	BUG_ON(sh->batch_head);
1877 	pr_debug("%s: stripe %llu\n", __func__,
1878 		(unsigned long long)sh->sector);
1879 
1880 	for (i = disks; i--; ) {
1881 		struct r5dev *dev = &sh->dev[i];
1882 		/* Only process blocks that are known to be uptodate */
1883 		if (test_bit(R5_InJournal, &dev->flags)) {
1884 			/*
1885 			 * For this case, PAGE_SIZE must be equal to 4KB and
1886 			 * page offset is zero.
1887 			 */
1888 			off_srcs[count] = dev->offset;
1889 			xor_srcs[count++] = dev->orig_page;
1890 		} else if (test_bit(R5_Wantdrain, &dev->flags)) {
1891 			off_srcs[count] = dev->offset;
1892 			xor_srcs[count++] = dev->page;
1893 		}
1894 	}
1895 
1896 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1897 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1898 	tx = async_xor_offs(xor_dest, off_dest, xor_srcs, off_srcs, count,
1899 			RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1900 
1901 	return tx;
1902 }
1903 
1904 static struct dma_async_tx_descriptor *
1905 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1906 		struct dma_async_tx_descriptor *tx)
1907 {
1908 	struct page **blocks = to_addr_page(percpu, 0);
1909 	unsigned int *offs = to_addr_offs(sh, percpu);
1910 	int count;
1911 	struct async_submit_ctl submit;
1912 
1913 	pr_debug("%s: stripe %llu\n", __func__,
1914 		(unsigned long long)sh->sector);
1915 
1916 	count = set_syndrome_sources(blocks, offs, sh, SYNDROME_SRC_WANT_DRAIN);
1917 
1918 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1919 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1920 	tx = async_gen_syndrome(blocks, offs, count+2,
1921 			RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
1922 
1923 	return tx;
1924 }
1925 
1926 static struct dma_async_tx_descriptor *
1927 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1928 {
1929 	struct r5conf *conf = sh->raid_conf;
1930 	int disks = sh->disks;
1931 	int i;
1932 	struct stripe_head *head_sh = sh;
1933 
1934 	pr_debug("%s: stripe %llu\n", __func__,
1935 		(unsigned long long)sh->sector);
1936 
1937 	for (i = disks; i--; ) {
1938 		struct r5dev *dev;
1939 		struct bio *chosen;
1940 
1941 		sh = head_sh;
1942 		if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1943 			struct bio *wbi;
1944 
1945 again:
1946 			dev = &sh->dev[i];
1947 			/*
1948 			 * clear R5_InJournal, so when rewriting a page in
1949 			 * journal, it is not skipped by r5l_log_stripe()
1950 			 */
1951 			clear_bit(R5_InJournal, &dev->flags);
1952 			spin_lock_irq(&sh->stripe_lock);
1953 			chosen = dev->towrite;
1954 			dev->towrite = NULL;
1955 			sh->overwrite_disks = 0;
1956 			BUG_ON(dev->written);
1957 			wbi = dev->written = chosen;
1958 			spin_unlock_irq(&sh->stripe_lock);
1959 			WARN_ON(dev->page != dev->orig_page);
1960 
1961 			while (wbi && wbi->bi_iter.bi_sector <
1962 				dev->sector + RAID5_STRIPE_SECTORS(conf)) {
1963 				if (wbi->bi_opf & REQ_FUA)
1964 					set_bit(R5_WantFUA, &dev->flags);
1965 				if (wbi->bi_opf & REQ_SYNC)
1966 					set_bit(R5_SyncIO, &dev->flags);
1967 				if (bio_op(wbi) == REQ_OP_DISCARD)
1968 					set_bit(R5_Discard, &dev->flags);
1969 				else {
1970 					tx = async_copy_data(1, wbi, &dev->page,
1971 							     dev->offset,
1972 							     dev->sector, tx, sh,
1973 							     r5c_is_writeback(conf->log));
1974 					if (dev->page != dev->orig_page &&
1975 					    !r5c_is_writeback(conf->log)) {
1976 						set_bit(R5_SkipCopy, &dev->flags);
1977 						clear_bit(R5_UPTODATE, &dev->flags);
1978 						clear_bit(R5_OVERWRITE, &dev->flags);
1979 					}
1980 				}
1981 				wbi = r5_next_bio(conf, wbi, dev->sector);
1982 			}
1983 
1984 			if (head_sh->batch_head) {
1985 				sh = list_first_entry(&sh->batch_list,
1986 						      struct stripe_head,
1987 						      batch_list);
1988 				if (sh == head_sh)
1989 					continue;
1990 				goto again;
1991 			}
1992 		}
1993 	}
1994 
1995 	return tx;
1996 }
1997 
1998 static void ops_complete_reconstruct(void *stripe_head_ref)
1999 {
2000 	struct stripe_head *sh = stripe_head_ref;
2001 	int disks = sh->disks;
2002 	int pd_idx = sh->pd_idx;
2003 	int qd_idx = sh->qd_idx;
2004 	int i;
2005 	bool fua = false, sync = false, discard = false;
2006 
2007 	pr_debug("%s: stripe %llu\n", __func__,
2008 		(unsigned long long)sh->sector);
2009 
2010 	for (i = disks; i--; ) {
2011 		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
2012 		sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
2013 		discard |= test_bit(R5_Discard, &sh->dev[i].flags);
2014 	}
2015 
2016 	for (i = disks; i--; ) {
2017 		struct r5dev *dev = &sh->dev[i];
2018 
2019 		if (dev->written || i == pd_idx || i == qd_idx) {
2020 			if (!discard && !test_bit(R5_SkipCopy, &dev->flags)) {
2021 				set_bit(R5_UPTODATE, &dev->flags);
2022 				if (test_bit(STRIPE_EXPAND_READY, &sh->state))
2023 					set_bit(R5_Expanded, &dev->flags);
2024 			}
2025 			if (fua)
2026 				set_bit(R5_WantFUA, &dev->flags);
2027 			if (sync)
2028 				set_bit(R5_SyncIO, &dev->flags);
2029 		}
2030 	}
2031 
2032 	if (sh->reconstruct_state == reconstruct_state_drain_run)
2033 		sh->reconstruct_state = reconstruct_state_drain_result;
2034 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
2035 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
2036 	else {
2037 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
2038 		sh->reconstruct_state = reconstruct_state_result;
2039 	}
2040 
2041 	set_bit(STRIPE_HANDLE, &sh->state);
2042 	raid5_release_stripe(sh);
2043 }
2044 
2045 static void
2046 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
2047 		     struct dma_async_tx_descriptor *tx)
2048 {
2049 	int disks = sh->disks;
2050 	struct page **xor_srcs;
2051 	unsigned int *off_srcs;
2052 	struct async_submit_ctl submit;
2053 	int count, pd_idx = sh->pd_idx, i;
2054 	struct page *xor_dest;
2055 	unsigned int off_dest;
2056 	int prexor = 0;
2057 	unsigned long flags;
2058 	int j = 0;
2059 	struct stripe_head *head_sh = sh;
2060 	int last_stripe;
2061 
2062 	pr_debug("%s: stripe %llu\n", __func__,
2063 		(unsigned long long)sh->sector);
2064 
2065 	for (i = 0; i < sh->disks; i++) {
2066 		if (pd_idx == i)
2067 			continue;
2068 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
2069 			break;
2070 	}
2071 	if (i >= sh->disks) {
2072 		atomic_inc(&sh->count);
2073 		set_bit(R5_Discard, &sh->dev[pd_idx].flags);
2074 		ops_complete_reconstruct(sh);
2075 		return;
2076 	}
2077 again:
2078 	count = 0;
2079 	xor_srcs = to_addr_page(percpu, j);
2080 	off_srcs = to_addr_offs(sh, percpu);
2081 	/* check if prexor is active which means only process blocks
2082 	 * that are part of a read-modify-write (written)
2083 	 */
2084 	if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
2085 		prexor = 1;
2086 		off_dest = off_srcs[count] = sh->dev[pd_idx].offset;
2087 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
2088 		for (i = disks; i--; ) {
2089 			struct r5dev *dev = &sh->dev[i];
2090 			if (head_sh->dev[i].written ||
2091 			    test_bit(R5_InJournal, &head_sh->dev[i].flags)) {
2092 				off_srcs[count] = dev->offset;
2093 				xor_srcs[count++] = dev->page;
2094 			}
2095 		}
2096 	} else {
2097 		xor_dest = sh->dev[pd_idx].page;
2098 		off_dest = sh->dev[pd_idx].offset;
2099 		for (i = disks; i--; ) {
2100 			struct r5dev *dev = &sh->dev[i];
2101 			if (i != pd_idx) {
2102 				off_srcs[count] = dev->offset;
2103 				xor_srcs[count++] = dev->page;
2104 			}
2105 		}
2106 	}
2107 
2108 	/* 1/ if we prexor'd then the dest is reused as a source
2109 	 * 2/ if we did not prexor then we are redoing the parity
2110 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
2111 	 * for the synchronous xor case
2112 	 */
2113 	last_stripe = !head_sh->batch_head ||
2114 		list_first_entry(&sh->batch_list,
2115 				 struct stripe_head, batch_list) == head_sh;
2116 	if (last_stripe) {
2117 		flags = ASYNC_TX_ACK |
2118 			(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
2119 
2120 		atomic_inc(&head_sh->count);
2121 		init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
2122 				  to_addr_conv(sh, percpu, j));
2123 	} else {
2124 		flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
2125 		init_async_submit(&submit, flags, tx, NULL, NULL,
2126 				  to_addr_conv(sh, percpu, j));
2127 	}
2128 
2129 	if (unlikely(count == 1))
2130 		tx = async_memcpy(xor_dest, xor_srcs[0], off_dest, off_srcs[0],
2131 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
2132 	else
2133 		tx = async_xor_offs(xor_dest, off_dest, xor_srcs, off_srcs, count,
2134 				RAID5_STRIPE_SIZE(sh->raid_conf), &submit);
2135 	if (!last_stripe) {
2136 		j++;
2137 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
2138 				      batch_list);
2139 		goto again;
2140 	}
2141 }
2142 
2143 static void
2144 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
2145 		     struct dma_async_tx_descriptor *tx)
2146 {
2147 	struct async_submit_ctl submit;
2148 	struct page **blocks;
2149 	unsigned int *offs;
2150 	int count, i, j = 0;
2151 	struct stripe_head *head_sh = sh;
2152 	int last_stripe;
2153 	int synflags;
2154 	unsigned long txflags;
2155 
2156 	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
2157 
2158 	for (i = 0; i < sh->disks; i++) {
2159 		if (sh->pd_idx == i || sh->qd_idx == i)
2160 			continue;
2161 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
2162 			break;
2163 	}
2164 	if (i >= sh->disks) {
2165 		atomic_inc(&sh->count);
2166 		set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
2167 		set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
2168 		ops_complete_reconstruct(sh);
2169 		return;
2170 	}
2171 
2172 again:
2173 	blocks = to_addr_page(percpu, j);
2174 	offs = to_addr_offs(sh, percpu);
2175 
2176 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
2177 		synflags = SYNDROME_SRC_WRITTEN;
2178 		txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
2179 	} else {
2180 		synflags = SYNDROME_SRC_ALL;
2181 		txflags = ASYNC_TX_ACK;
2182 	}
2183 
2184 	count = set_syndrome_sources(blocks, offs, sh, synflags);
2185 	last_stripe = !head_sh->batch_head ||
2186 		list_first_entry(&sh->batch_list,
2187 				 struct stripe_head, batch_list) == head_sh;
2188 
2189 	if (last_stripe) {
2190 		atomic_inc(&head_sh->count);
2191 		init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
2192 				  head_sh, to_addr_conv(sh, percpu, j));
2193 	} else
2194 		init_async_submit(&submit, 0, tx, NULL, NULL,
2195 				  to_addr_conv(sh, percpu, j));
2196 	tx = async_gen_syndrome(blocks, offs, count+2,
2197 			RAID5_STRIPE_SIZE(sh->raid_conf),  &submit);
2198 	if (!last_stripe) {
2199 		j++;
2200 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
2201 				      batch_list);
2202 		goto again;
2203 	}
2204 }
2205 
2206 static void ops_complete_check(void *stripe_head_ref)
2207 {
2208 	struct stripe_head *sh = stripe_head_ref;
2209 
2210 	pr_debug("%s: stripe %llu\n", __func__,
2211 		(unsigned long long)sh->sector);
2212 
2213 	sh->check_state = check_state_check_result;
2214 	set_bit(STRIPE_HANDLE, &sh->state);
2215 	raid5_release_stripe(sh);
2216 }
2217 
2218 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
2219 {
2220 	int disks = sh->disks;
2221 	int pd_idx = sh->pd_idx;
2222 	int qd_idx = sh->qd_idx;
2223 	struct page *xor_dest;
2224 	unsigned int off_dest;
2225 	struct page **xor_srcs = to_addr_page(percpu, 0);
2226 	unsigned int *off_srcs = to_addr_offs(sh, percpu);
2227 	struct dma_async_tx_descriptor *tx;
2228 	struct async_submit_ctl submit;
2229 	int count;
2230 	int i;
2231 
2232 	pr_debug("%s: stripe %llu\n", __func__,
2233 		(unsigned long long)sh->sector);
2234 
2235 	BUG_ON(sh->batch_head);
2236 	count = 0;
2237 	xor_dest = sh->dev[pd_idx].page;
2238 	off_dest = sh->dev[pd_idx].offset;
2239 	off_srcs[count] = off_dest;
2240 	xor_srcs[count++] = xor_dest;
2241 	for (i = disks; i--; ) {
2242 		if (i == pd_idx || i == qd_idx)
2243 			continue;
2244 		off_srcs[count] = sh->dev[i].offset;
2245 		xor_srcs[count++] = sh->dev[i].page;
2246 	}
2247 
2248 	init_async_submit(&submit, 0, NULL, NULL, NULL,
2249 			  to_addr_conv(sh, percpu, 0));
2250 	tx = async_xor_val_offs(xor_dest, off_dest, xor_srcs, off_srcs, count,
2251 			   RAID5_STRIPE_SIZE(sh->raid_conf),
2252 			   &sh->ops.zero_sum_result, &submit);
2253 
2254 	atomic_inc(&sh->count);
2255 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
2256 	tx = async_trigger_callback(&submit);
2257 }
2258 
2259 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
2260 {
2261 	struct page **srcs = to_addr_page(percpu, 0);
2262 	unsigned int *offs = to_addr_offs(sh, percpu);
2263 	struct async_submit_ctl submit;
2264 	int count;
2265 
2266 	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
2267 		(unsigned long long)sh->sector, checkp);
2268 
2269 	BUG_ON(sh->batch_head);
2270 	count = set_syndrome_sources(srcs, offs, sh, SYNDROME_SRC_ALL);
2271 	if (!checkp)
2272 		srcs[count] = NULL;
2273 
2274 	atomic_inc(&sh->count);
2275 	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
2276 			  sh, to_addr_conv(sh, percpu, 0));
2277 	async_syndrome_val(srcs, offs, count+2,
2278 			   RAID5_STRIPE_SIZE(sh->raid_conf),
2279 			   &sh->ops.zero_sum_result, percpu->spare_page, 0, &submit);
2280 }
2281 
2282 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
2283 {
2284 	int overlap_clear = 0, i, disks = sh->disks;
2285 	struct dma_async_tx_descriptor *tx = NULL;
2286 	struct r5conf *conf = sh->raid_conf;
2287 	int level = conf->level;
2288 	struct raid5_percpu *percpu;
2289 
2290 	local_lock(&conf->percpu->lock);
2291 	percpu = this_cpu_ptr(conf->percpu);
2292 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
2293 		ops_run_biofill(sh);
2294 		overlap_clear++;
2295 	}
2296 
2297 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
2298 		if (level < 6)
2299 			tx = ops_run_compute5(sh, percpu);
2300 		else {
2301 			if (sh->ops.target2 < 0 || sh->ops.target < 0)
2302 				tx = ops_run_compute6_1(sh, percpu);
2303 			else
2304 				tx = ops_run_compute6_2(sh, percpu);
2305 		}
2306 		/* terminate the chain if reconstruct is not set to be run */
2307 		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
2308 			async_tx_ack(tx);
2309 	}
2310 
2311 	if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
2312 		if (level < 6)
2313 			tx = ops_run_prexor5(sh, percpu, tx);
2314 		else
2315 			tx = ops_run_prexor6(sh, percpu, tx);
2316 	}
2317 
2318 	if (test_bit(STRIPE_OP_PARTIAL_PARITY, &ops_request))
2319 		tx = ops_run_partial_parity(sh, percpu, tx);
2320 
2321 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
2322 		tx = ops_run_biodrain(sh, tx);
2323 		overlap_clear++;
2324 	}
2325 
2326 	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
2327 		if (level < 6)
2328 			ops_run_reconstruct5(sh, percpu, tx);
2329 		else
2330 			ops_run_reconstruct6(sh, percpu, tx);
2331 	}
2332 
2333 	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
2334 		if (sh->check_state == check_state_run)
2335 			ops_run_check_p(sh, percpu);
2336 		else if (sh->check_state == check_state_run_q)
2337 			ops_run_check_pq(sh, percpu, 0);
2338 		else if (sh->check_state == check_state_run_pq)
2339 			ops_run_check_pq(sh, percpu, 1);
2340 		else
2341 			BUG();
2342 	}
2343 
2344 	if (overlap_clear && !sh->batch_head) {
2345 		for (i = disks; i--; ) {
2346 			struct r5dev *dev = &sh->dev[i];
2347 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
2348 				wake_up(&sh->raid_conf->wait_for_overlap);
2349 		}
2350 	}
2351 	local_unlock(&conf->percpu->lock);
2352 }
2353 
2354 static void free_stripe(struct kmem_cache *sc, struct stripe_head *sh)
2355 {
2356 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
2357 	kfree(sh->pages);
2358 #endif
2359 	if (sh->ppl_page)
2360 		__free_page(sh->ppl_page);
2361 	kmem_cache_free(sc, sh);
2362 }
2363 
2364 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
2365 	int disks, struct r5conf *conf)
2366 {
2367 	struct stripe_head *sh;
2368 
2369 	sh = kmem_cache_zalloc(sc, gfp);
2370 	if (sh) {
2371 		spin_lock_init(&sh->stripe_lock);
2372 		spin_lock_init(&sh->batch_lock);
2373 		INIT_LIST_HEAD(&sh->batch_list);
2374 		INIT_LIST_HEAD(&sh->lru);
2375 		INIT_LIST_HEAD(&sh->r5c);
2376 		INIT_LIST_HEAD(&sh->log_list);
2377 		atomic_set(&sh->count, 1);
2378 		sh->raid_conf = conf;
2379 		sh->log_start = MaxSector;
2380 
2381 		if (raid5_has_ppl(conf)) {
2382 			sh->ppl_page = alloc_page(gfp);
2383 			if (!sh->ppl_page) {
2384 				free_stripe(sc, sh);
2385 				return NULL;
2386 			}
2387 		}
2388 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
2389 		if (init_stripe_shared_pages(sh, conf, disks)) {
2390 			free_stripe(sc, sh);
2391 			return NULL;
2392 		}
2393 #endif
2394 	}
2395 	return sh;
2396 }
2397 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2398 {
2399 	struct stripe_head *sh;
2400 
2401 	sh = alloc_stripe(conf->slab_cache, gfp, conf->pool_size, conf);
2402 	if (!sh)
2403 		return 0;
2404 
2405 	if (grow_buffers(sh, gfp)) {
2406 		shrink_buffers(sh);
2407 		free_stripe(conf->slab_cache, sh);
2408 		return 0;
2409 	}
2410 	sh->hash_lock_index =
2411 		conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2412 	/* we just created an active stripe so... */
2413 	atomic_inc(&conf->active_stripes);
2414 
2415 	raid5_release_stripe(sh);
2416 	conf->max_nr_stripes++;
2417 	return 1;
2418 }
2419 
2420 static int grow_stripes(struct r5conf *conf, int num)
2421 {
2422 	struct kmem_cache *sc;
2423 	size_t namelen = sizeof(conf->cache_name[0]);
2424 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
2425 
2426 	if (conf->mddev->gendisk)
2427 		snprintf(conf->cache_name[0], namelen,
2428 			"raid%d-%s", conf->level, mdname(conf->mddev));
2429 	else
2430 		snprintf(conf->cache_name[0], namelen,
2431 			"raid%d-%p", conf->level, conf->mddev);
2432 	snprintf(conf->cache_name[1], namelen, "%.27s-alt", conf->cache_name[0]);
2433 
2434 	conf->active_name = 0;
2435 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
2436 			       struct_size_t(struct stripe_head, dev, devs),
2437 			       0, 0, NULL);
2438 	if (!sc)
2439 		return 1;
2440 	conf->slab_cache = sc;
2441 	conf->pool_size = devs;
2442 	while (num--)
2443 		if (!grow_one_stripe(conf, GFP_KERNEL))
2444 			return 1;
2445 
2446 	return 0;
2447 }
2448 
2449 /**
2450  * scribble_alloc - allocate percpu scribble buffer for required size
2451  *		    of the scribble region
2452  * @percpu: from for_each_present_cpu() of the caller
2453  * @num: total number of disks in the array
2454  * @cnt: scribble objs count for required size of the scribble region
2455  *
2456  * The scribble buffer size must be enough to contain:
2457  * 1/ a struct page pointer for each device in the array +2
2458  * 2/ room to convert each entry in (1) to its corresponding dma
2459  *    (dma_map_page()) or page (page_address()) address.
2460  *
2461  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2462  * calculate over all devices (not just the data blocks), using zeros in place
2463  * of the P and Q blocks.
2464  */
2465 static int scribble_alloc(struct raid5_percpu *percpu,
2466 			  int num, int cnt)
2467 {
2468 	size_t obj_size =
2469 		sizeof(struct page *) * (num + 2) +
2470 		sizeof(addr_conv_t) * (num + 2) +
2471 		sizeof(unsigned int) * (num + 2);
2472 	void *scribble;
2473 
2474 	/*
2475 	 * If here is in raid array suspend context, it is in memalloc noio
2476 	 * context as well, there is no potential recursive memory reclaim
2477 	 * I/Os with the GFP_KERNEL flag.
2478 	 */
2479 	scribble = kvmalloc_array(cnt, obj_size, GFP_KERNEL);
2480 	if (!scribble)
2481 		return -ENOMEM;
2482 
2483 	kvfree(percpu->scribble);
2484 
2485 	percpu->scribble = scribble;
2486 	percpu->scribble_obj_size = obj_size;
2487 	return 0;
2488 }
2489 
2490 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2491 {
2492 	unsigned long cpu;
2493 	int err = 0;
2494 
2495 	/*
2496 	 * Never shrink. And mddev_suspend() could deadlock if this is called
2497 	 * from raid5d. In that case, scribble_disks and scribble_sectors
2498 	 * should equal to new_disks and new_sectors
2499 	 */
2500 	if (conf->scribble_disks >= new_disks &&
2501 	    conf->scribble_sectors >= new_sectors)
2502 		return 0;
2503 	mddev_suspend(conf->mddev);
2504 	cpus_read_lock();
2505 
2506 	for_each_present_cpu(cpu) {
2507 		struct raid5_percpu *percpu;
2508 
2509 		percpu = per_cpu_ptr(conf->percpu, cpu);
2510 		err = scribble_alloc(percpu, new_disks,
2511 				     new_sectors / RAID5_STRIPE_SECTORS(conf));
2512 		if (err)
2513 			break;
2514 	}
2515 
2516 	cpus_read_unlock();
2517 	mddev_resume(conf->mddev);
2518 	if (!err) {
2519 		conf->scribble_disks = new_disks;
2520 		conf->scribble_sectors = new_sectors;
2521 	}
2522 	return err;
2523 }
2524 
2525 static int resize_stripes(struct r5conf *conf, int newsize)
2526 {
2527 	/* Make all the stripes able to hold 'newsize' devices.
2528 	 * New slots in each stripe get 'page' set to a new page.
2529 	 *
2530 	 * This happens in stages:
2531 	 * 1/ create a new kmem_cache and allocate the required number of
2532 	 *    stripe_heads.
2533 	 * 2/ gather all the old stripe_heads and transfer the pages across
2534 	 *    to the new stripe_heads.  This will have the side effect of
2535 	 *    freezing the array as once all stripe_heads have been collected,
2536 	 *    no IO will be possible.  Old stripe heads are freed once their
2537 	 *    pages have been transferred over, and the old kmem_cache is
2538 	 *    freed when all stripes are done.
2539 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2540 	 *    we simple return a failure status - no need to clean anything up.
2541 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
2542 	 *    If this fails, we don't bother trying the shrink the
2543 	 *    stripe_heads down again, we just leave them as they are.
2544 	 *    As each stripe_head is processed the new one is released into
2545 	 *    active service.
2546 	 *
2547 	 * Once step2 is started, we cannot afford to wait for a write,
2548 	 * so we use GFP_NOIO allocations.
2549 	 */
2550 	struct stripe_head *osh, *nsh;
2551 	LIST_HEAD(newstripes);
2552 	struct disk_info *ndisks;
2553 	int err = 0;
2554 	struct kmem_cache *sc;
2555 	int i;
2556 	int hash, cnt;
2557 
2558 	md_allow_write(conf->mddev);
2559 
2560 	/* Step 1 */
2561 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2562 			       struct_size_t(struct stripe_head, dev, newsize),
2563 			       0, 0, NULL);
2564 	if (!sc)
2565 		return -ENOMEM;
2566 
2567 	/* Need to ensure auto-resizing doesn't interfere */
2568 	mutex_lock(&conf->cache_size_mutex);
2569 
2570 	for (i = conf->max_nr_stripes; i; i--) {
2571 		nsh = alloc_stripe(sc, GFP_KERNEL, newsize, conf);
2572 		if (!nsh)
2573 			break;
2574 
2575 		list_add(&nsh->lru, &newstripes);
2576 	}
2577 	if (i) {
2578 		/* didn't get enough, give up */
2579 		while (!list_empty(&newstripes)) {
2580 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
2581 			list_del(&nsh->lru);
2582 			free_stripe(sc, nsh);
2583 		}
2584 		kmem_cache_destroy(sc);
2585 		mutex_unlock(&conf->cache_size_mutex);
2586 		return -ENOMEM;
2587 	}
2588 	/* Step 2 - Must use GFP_NOIO now.
2589 	 * OK, we have enough stripes, start collecting inactive
2590 	 * stripes and copying them over
2591 	 */
2592 	hash = 0;
2593 	cnt = 0;
2594 	list_for_each_entry(nsh, &newstripes, lru) {
2595 		lock_device_hash_lock(conf, hash);
2596 		wait_event_cmd(conf->wait_for_stripe,
2597 				    !list_empty(conf->inactive_list + hash),
2598 				    unlock_device_hash_lock(conf, hash),
2599 				    lock_device_hash_lock(conf, hash));
2600 		osh = get_free_stripe(conf, hash);
2601 		unlock_device_hash_lock(conf, hash);
2602 
2603 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
2604 	for (i = 0; i < osh->nr_pages; i++) {
2605 		nsh->pages[i] = osh->pages[i];
2606 		osh->pages[i] = NULL;
2607 	}
2608 #endif
2609 		for(i=0; i<conf->pool_size; i++) {
2610 			nsh->dev[i].page = osh->dev[i].page;
2611 			nsh->dev[i].orig_page = osh->dev[i].page;
2612 			nsh->dev[i].offset = osh->dev[i].offset;
2613 		}
2614 		nsh->hash_lock_index = hash;
2615 		free_stripe(conf->slab_cache, osh);
2616 		cnt++;
2617 		if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2618 		    !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2619 			hash++;
2620 			cnt = 0;
2621 		}
2622 	}
2623 	kmem_cache_destroy(conf->slab_cache);
2624 
2625 	/* Step 3.
2626 	 * At this point, we are holding all the stripes so the array
2627 	 * is completely stalled, so now is a good time to resize
2628 	 * conf->disks and the scribble region
2629 	 */
2630 	ndisks = kcalloc(newsize, sizeof(struct disk_info), GFP_NOIO);
2631 	if (ndisks) {
2632 		for (i = 0; i < conf->pool_size; i++)
2633 			ndisks[i] = conf->disks[i];
2634 
2635 		for (i = conf->pool_size; i < newsize; i++) {
2636 			ndisks[i].extra_page = alloc_page(GFP_NOIO);
2637 			if (!ndisks[i].extra_page)
2638 				err = -ENOMEM;
2639 		}
2640 
2641 		if (err) {
2642 			for (i = conf->pool_size; i < newsize; i++)
2643 				if (ndisks[i].extra_page)
2644 					put_page(ndisks[i].extra_page);
2645 			kfree(ndisks);
2646 		} else {
2647 			kfree(conf->disks);
2648 			conf->disks = ndisks;
2649 		}
2650 	} else
2651 		err = -ENOMEM;
2652 
2653 	conf->slab_cache = sc;
2654 	conf->active_name = 1-conf->active_name;
2655 
2656 	/* Step 4, return new stripes to service */
2657 	while(!list_empty(&newstripes)) {
2658 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
2659 		list_del_init(&nsh->lru);
2660 
2661 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
2662 		for (i = 0; i < nsh->nr_pages; i++) {
2663 			if (nsh->pages[i])
2664 				continue;
2665 			nsh->pages[i] = alloc_page(GFP_NOIO);
2666 			if (!nsh->pages[i])
2667 				err = -ENOMEM;
2668 		}
2669 
2670 		for (i = conf->raid_disks; i < newsize; i++) {
2671 			if (nsh->dev[i].page)
2672 				continue;
2673 			nsh->dev[i].page = raid5_get_dev_page(nsh, i);
2674 			nsh->dev[i].orig_page = nsh->dev[i].page;
2675 			nsh->dev[i].offset = raid5_get_page_offset(nsh, i);
2676 		}
2677 #else
2678 		for (i=conf->raid_disks; i < newsize; i++)
2679 			if (nsh->dev[i].page == NULL) {
2680 				struct page *p = alloc_page(GFP_NOIO);
2681 				nsh->dev[i].page = p;
2682 				nsh->dev[i].orig_page = p;
2683 				nsh->dev[i].offset = 0;
2684 				if (!p)
2685 					err = -ENOMEM;
2686 			}
2687 #endif
2688 		raid5_release_stripe(nsh);
2689 	}
2690 	/* critical section pass, GFP_NOIO no longer needed */
2691 
2692 	if (!err)
2693 		conf->pool_size = newsize;
2694 	mutex_unlock(&conf->cache_size_mutex);
2695 
2696 	return err;
2697 }
2698 
2699 static int drop_one_stripe(struct r5conf *conf)
2700 {
2701 	struct stripe_head *sh;
2702 	int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2703 
2704 	spin_lock_irq(conf->hash_locks + hash);
2705 	sh = get_free_stripe(conf, hash);
2706 	spin_unlock_irq(conf->hash_locks + hash);
2707 	if (!sh)
2708 		return 0;
2709 	BUG_ON(atomic_read(&sh->count));
2710 	shrink_buffers(sh);
2711 	free_stripe(conf->slab_cache, sh);
2712 	atomic_dec(&conf->active_stripes);
2713 	conf->max_nr_stripes--;
2714 	return 1;
2715 }
2716 
2717 static void shrink_stripes(struct r5conf *conf)
2718 {
2719 	while (conf->max_nr_stripes &&
2720 	       drop_one_stripe(conf))
2721 		;
2722 
2723 	kmem_cache_destroy(conf->slab_cache);
2724 	conf->slab_cache = NULL;
2725 }
2726 
2727 /*
2728  * This helper wraps rcu_dereference_protected() and can be used when
2729  * it is known that the nr_pending of the rdev is elevated.
2730  */
2731 static struct md_rdev *rdev_pend_deref(struct md_rdev __rcu *rdev)
2732 {
2733 	return rcu_dereference_protected(rdev,
2734 			atomic_read(&rcu_access_pointer(rdev)->nr_pending));
2735 }
2736 
2737 /*
2738  * This helper wraps rcu_dereference_protected() and should be used
2739  * when it is known that the mddev_lock() is held. This is safe
2740  * seeing raid5_remove_disk() has the same lock held.
2741  */
2742 static struct md_rdev *rdev_mdlock_deref(struct mddev *mddev,
2743 					 struct md_rdev __rcu *rdev)
2744 {
2745 	return rcu_dereference_protected(rdev,
2746 			lockdep_is_held(&mddev->reconfig_mutex));
2747 }
2748 
2749 static void raid5_end_read_request(struct bio * bi)
2750 {
2751 	struct stripe_head *sh = bi->bi_private;
2752 	struct r5conf *conf = sh->raid_conf;
2753 	int disks = sh->disks, i;
2754 	struct md_rdev *rdev = NULL;
2755 	sector_t s;
2756 
2757 	for (i=0 ; i<disks; i++)
2758 		if (bi == &sh->dev[i].req)
2759 			break;
2760 
2761 	pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2762 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2763 		bi->bi_status);
2764 	if (i == disks) {
2765 		BUG();
2766 		return;
2767 	}
2768 	if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2769 		/* If replacement finished while this request was outstanding,
2770 		 * 'replacement' might be NULL already.
2771 		 * In that case it moved down to 'rdev'.
2772 		 * rdev is not removed until all requests are finished.
2773 		 */
2774 		rdev = rdev_pend_deref(conf->disks[i].replacement);
2775 	if (!rdev)
2776 		rdev = rdev_pend_deref(conf->disks[i].rdev);
2777 
2778 	if (use_new_offset(conf, sh))
2779 		s = sh->sector + rdev->new_data_offset;
2780 	else
2781 		s = sh->sector + rdev->data_offset;
2782 	if (!bi->bi_status) {
2783 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
2784 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2785 			/* Note that this cannot happen on a
2786 			 * replacement device.  We just fail those on
2787 			 * any error
2788 			 */
2789 			pr_info_ratelimited(
2790 				"md/raid:%s: read error corrected (%lu sectors at %llu on %pg)\n",
2791 				mdname(conf->mddev), RAID5_STRIPE_SECTORS(conf),
2792 				(unsigned long long)s,
2793 				rdev->bdev);
2794 			atomic_add(RAID5_STRIPE_SECTORS(conf), &rdev->corrected_errors);
2795 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2796 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2797 		} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2798 			clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2799 
2800 		if (test_bit(R5_InJournal, &sh->dev[i].flags))
2801 			/*
2802 			 * end read for a page in journal, this
2803 			 * must be preparing for prexor in rmw
2804 			 */
2805 			set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
2806 
2807 		if (atomic_read(&rdev->read_errors))
2808 			atomic_set(&rdev->read_errors, 0);
2809 	} else {
2810 		int retry = 0;
2811 		int set_bad = 0;
2812 
2813 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2814 		if (!(bi->bi_status == BLK_STS_PROTECTION))
2815 			atomic_inc(&rdev->read_errors);
2816 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2817 			pr_warn_ratelimited(
2818 				"md/raid:%s: read error on replacement device (sector %llu on %pg).\n",
2819 				mdname(conf->mddev),
2820 				(unsigned long long)s,
2821 				rdev->bdev);
2822 		else if (conf->mddev->degraded >= conf->max_degraded) {
2823 			set_bad = 1;
2824 			pr_warn_ratelimited(
2825 				"md/raid:%s: read error not correctable (sector %llu on %pg).\n",
2826 				mdname(conf->mddev),
2827 				(unsigned long long)s,
2828 				rdev->bdev);
2829 		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2830 			/* Oh, no!!! */
2831 			set_bad = 1;
2832 			pr_warn_ratelimited(
2833 				"md/raid:%s: read error NOT corrected!! (sector %llu on %pg).\n",
2834 				mdname(conf->mddev),
2835 				(unsigned long long)s,
2836 				rdev->bdev);
2837 		} else if (atomic_read(&rdev->read_errors)
2838 			 > conf->max_nr_stripes) {
2839 			if (!test_bit(Faulty, &rdev->flags)) {
2840 				pr_warn("md/raid:%s: %d read_errors > %d stripes\n",
2841 				    mdname(conf->mddev),
2842 				    atomic_read(&rdev->read_errors),
2843 				    conf->max_nr_stripes);
2844 				pr_warn("md/raid:%s: Too many read errors, failing device %pg.\n",
2845 				    mdname(conf->mddev), rdev->bdev);
2846 			}
2847 		} else
2848 			retry = 1;
2849 		if (set_bad && test_bit(In_sync, &rdev->flags)
2850 		    && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2851 			retry = 1;
2852 		if (retry)
2853 			if (sh->qd_idx >= 0 && sh->pd_idx == i)
2854 				set_bit(R5_ReadError, &sh->dev[i].flags);
2855 			else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2856 				set_bit(R5_ReadError, &sh->dev[i].flags);
2857 				clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2858 			} else
2859 				set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2860 		else {
2861 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2862 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2863 			if (!(set_bad
2864 			      && test_bit(In_sync, &rdev->flags)
2865 			      && rdev_set_badblocks(
2866 				      rdev, sh->sector, RAID5_STRIPE_SECTORS(conf), 0)))
2867 				md_error(conf->mddev, rdev);
2868 		}
2869 	}
2870 	rdev_dec_pending(rdev, conf->mddev);
2871 	bio_uninit(bi);
2872 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
2873 	set_bit(STRIPE_HANDLE, &sh->state);
2874 	raid5_release_stripe(sh);
2875 }
2876 
2877 static void raid5_end_write_request(struct bio *bi)
2878 {
2879 	struct stripe_head *sh = bi->bi_private;
2880 	struct r5conf *conf = sh->raid_conf;
2881 	int disks = sh->disks, i;
2882 	struct md_rdev *rdev;
2883 	sector_t first_bad;
2884 	int bad_sectors;
2885 	int replacement = 0;
2886 
2887 	for (i = 0 ; i < disks; i++) {
2888 		if (bi == &sh->dev[i].req) {
2889 			rdev = rdev_pend_deref(conf->disks[i].rdev);
2890 			break;
2891 		}
2892 		if (bi == &sh->dev[i].rreq) {
2893 			rdev = rdev_pend_deref(conf->disks[i].replacement);
2894 			if (rdev)
2895 				replacement = 1;
2896 			else
2897 				/* rdev was removed and 'replacement'
2898 				 * replaced it.  rdev is not removed
2899 				 * until all requests are finished.
2900 				 */
2901 				rdev = rdev_pend_deref(conf->disks[i].rdev);
2902 			break;
2903 		}
2904 	}
2905 	pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2906 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2907 		bi->bi_status);
2908 	if (i == disks) {
2909 		BUG();
2910 		return;
2911 	}
2912 
2913 	if (replacement) {
2914 		if (bi->bi_status)
2915 			md_error(conf->mddev, rdev);
2916 		else if (is_badblock(rdev, sh->sector,
2917 				     RAID5_STRIPE_SECTORS(conf),
2918 				     &first_bad, &bad_sectors))
2919 			set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2920 	} else {
2921 		if (bi->bi_status) {
2922 			set_bit(STRIPE_DEGRADED, &sh->state);
2923 			set_bit(WriteErrorSeen, &rdev->flags);
2924 			set_bit(R5_WriteError, &sh->dev[i].flags);
2925 			if (!test_and_set_bit(WantReplacement, &rdev->flags))
2926 				set_bit(MD_RECOVERY_NEEDED,
2927 					&rdev->mddev->recovery);
2928 		} else if (is_badblock(rdev, sh->sector,
2929 				       RAID5_STRIPE_SECTORS(conf),
2930 				       &first_bad, &bad_sectors)) {
2931 			set_bit(R5_MadeGood, &sh->dev[i].flags);
2932 			if (test_bit(R5_ReadError, &sh->dev[i].flags))
2933 				/* That was a successful write so make
2934 				 * sure it looks like we already did
2935 				 * a re-write.
2936 				 */
2937 				set_bit(R5_ReWrite, &sh->dev[i].flags);
2938 		}
2939 	}
2940 	rdev_dec_pending(rdev, conf->mddev);
2941 
2942 	if (sh->batch_head && bi->bi_status && !replacement)
2943 		set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2944 
2945 	bio_uninit(bi);
2946 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2947 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2948 	set_bit(STRIPE_HANDLE, &sh->state);
2949 
2950 	if (sh->batch_head && sh != sh->batch_head)
2951 		raid5_release_stripe(sh->batch_head);
2952 	raid5_release_stripe(sh);
2953 }
2954 
2955 static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
2956 {
2957 	struct r5conf *conf = mddev->private;
2958 	unsigned long flags;
2959 	pr_debug("raid456: error called\n");
2960 
2961 	pr_crit("md/raid:%s: Disk failure on %pg, disabling device.\n",
2962 		mdname(mddev), rdev->bdev);
2963 
2964 	spin_lock_irqsave(&conf->device_lock, flags);
2965 	set_bit(Faulty, &rdev->flags);
2966 	clear_bit(In_sync, &rdev->flags);
2967 	mddev->degraded = raid5_calc_degraded(conf);
2968 
2969 	if (has_failed(conf)) {
2970 		set_bit(MD_BROKEN, &conf->mddev->flags);
2971 		conf->recovery_disabled = mddev->recovery_disabled;
2972 
2973 		pr_crit("md/raid:%s: Cannot continue operation (%d/%d failed).\n",
2974 			mdname(mddev), mddev->degraded, conf->raid_disks);
2975 	} else {
2976 		pr_crit("md/raid:%s: Operation continuing on %d devices.\n",
2977 			mdname(mddev), conf->raid_disks - mddev->degraded);
2978 	}
2979 
2980 	spin_unlock_irqrestore(&conf->device_lock, flags);
2981 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2982 
2983 	set_bit(Blocked, &rdev->flags);
2984 	set_mask_bits(&mddev->sb_flags, 0,
2985 		      BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
2986 	r5c_update_on_rdev_error(mddev, rdev);
2987 }
2988 
2989 /*
2990  * Input: a 'big' sector number,
2991  * Output: index of the data and parity disk, and the sector # in them.
2992  */
2993 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2994 			      int previous, int *dd_idx,
2995 			      struct stripe_head *sh)
2996 {
2997 	sector_t stripe, stripe2;
2998 	sector_t chunk_number;
2999 	unsigned int chunk_offset;
3000 	int pd_idx, qd_idx;
3001 	int ddf_layout = 0;
3002 	sector_t new_sector;
3003 	int algorithm = previous ? conf->prev_algo
3004 				 : conf->algorithm;
3005 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
3006 					 : conf->chunk_sectors;
3007 	int raid_disks = previous ? conf->previous_raid_disks
3008 				  : conf->raid_disks;
3009 	int data_disks = raid_disks - conf->max_degraded;
3010 
3011 	/* First compute the information on this sector */
3012 
3013 	/*
3014 	 * Compute the chunk number and the sector offset inside the chunk
3015 	 */
3016 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
3017 	chunk_number = r_sector;
3018 
3019 	/*
3020 	 * Compute the stripe number
3021 	 */
3022 	stripe = chunk_number;
3023 	*dd_idx = sector_div(stripe, data_disks);
3024 	stripe2 = stripe;
3025 	/*
3026 	 * Select the parity disk based on the user selected algorithm.
3027 	 */
3028 	pd_idx = qd_idx = -1;
3029 	switch(conf->level) {
3030 	case 4:
3031 		pd_idx = data_disks;
3032 		break;
3033 	case 5:
3034 		switch (algorithm) {
3035 		case ALGORITHM_LEFT_ASYMMETRIC:
3036 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
3037 			if (*dd_idx >= pd_idx)
3038 				(*dd_idx)++;
3039 			break;
3040 		case ALGORITHM_RIGHT_ASYMMETRIC:
3041 			pd_idx = sector_div(stripe2, raid_disks);
3042 			if (*dd_idx >= pd_idx)
3043 				(*dd_idx)++;
3044 			break;
3045 		case ALGORITHM_LEFT_SYMMETRIC:
3046 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
3047 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
3048 			break;
3049 		case ALGORITHM_RIGHT_SYMMETRIC:
3050 			pd_idx = sector_div(stripe2, raid_disks);
3051 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
3052 			break;
3053 		case ALGORITHM_PARITY_0:
3054 			pd_idx = 0;
3055 			(*dd_idx)++;
3056 			break;
3057 		case ALGORITHM_PARITY_N:
3058 			pd_idx = data_disks;
3059 			break;
3060 		default:
3061 			BUG();
3062 		}
3063 		break;
3064 	case 6:
3065 
3066 		switch (algorithm) {
3067 		case ALGORITHM_LEFT_ASYMMETRIC:
3068 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
3069 			qd_idx = pd_idx + 1;
3070 			if (pd_idx == raid_disks-1) {
3071 				(*dd_idx)++;	/* Q D D D P */
3072 				qd_idx = 0;
3073 			} else if (*dd_idx >= pd_idx)
3074 				(*dd_idx) += 2; /* D D P Q D */
3075 			break;
3076 		case ALGORITHM_RIGHT_ASYMMETRIC:
3077 			pd_idx = sector_div(stripe2, raid_disks);
3078 			qd_idx = pd_idx + 1;
3079 			if (pd_idx == raid_disks-1) {
3080 				(*dd_idx)++;	/* Q D D D P */
3081 				qd_idx = 0;
3082 			} else if (*dd_idx >= pd_idx)
3083 				(*dd_idx) += 2; /* D D P Q D */
3084 			break;
3085 		case ALGORITHM_LEFT_SYMMETRIC:
3086 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
3087 			qd_idx = (pd_idx + 1) % raid_disks;
3088 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
3089 			break;
3090 		case ALGORITHM_RIGHT_SYMMETRIC:
3091 			pd_idx = sector_div(stripe2, raid_disks);
3092 			qd_idx = (pd_idx + 1) % raid_disks;
3093 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
3094 			break;
3095 
3096 		case ALGORITHM_PARITY_0:
3097 			pd_idx = 0;
3098 			qd_idx = 1;
3099 			(*dd_idx) += 2;
3100 			break;
3101 		case ALGORITHM_PARITY_N:
3102 			pd_idx = data_disks;
3103 			qd_idx = data_disks + 1;
3104 			break;
3105 
3106 		case ALGORITHM_ROTATING_ZERO_RESTART:
3107 			/* Exactly the same as RIGHT_ASYMMETRIC, but or
3108 			 * of blocks for computing Q is different.
3109 			 */
3110 			pd_idx = sector_div(stripe2, raid_disks);
3111 			qd_idx = pd_idx + 1;
3112 			if (pd_idx == raid_disks-1) {
3113 				(*dd_idx)++;	/* Q D D D P */
3114 				qd_idx = 0;
3115 			} else if (*dd_idx >= pd_idx)
3116 				(*dd_idx) += 2; /* D D P Q D */
3117 			ddf_layout = 1;
3118 			break;
3119 
3120 		case ALGORITHM_ROTATING_N_RESTART:
3121 			/* Same a left_asymmetric, by first stripe is
3122 			 * D D D P Q  rather than
3123 			 * Q D D D P
3124 			 */
3125 			stripe2 += 1;
3126 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
3127 			qd_idx = pd_idx + 1;
3128 			if (pd_idx == raid_disks-1) {
3129 				(*dd_idx)++;	/* Q D D D P */
3130 				qd_idx = 0;
3131 			} else if (*dd_idx >= pd_idx)
3132 				(*dd_idx) += 2; /* D D P Q D */
3133 			ddf_layout = 1;
3134 			break;
3135 
3136 		case ALGORITHM_ROTATING_N_CONTINUE:
3137 			/* Same as left_symmetric but Q is before P */
3138 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
3139 			qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
3140 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
3141 			ddf_layout = 1;
3142 			break;
3143 
3144 		case ALGORITHM_LEFT_ASYMMETRIC_6:
3145 			/* RAID5 left_asymmetric, with Q on last device */
3146 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
3147 			if (*dd_idx >= pd_idx)
3148 				(*dd_idx)++;
3149 			qd_idx = raid_disks - 1;
3150 			break;
3151 
3152 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
3153 			pd_idx = sector_div(stripe2, raid_disks-1);
3154 			if (*dd_idx >= pd_idx)
3155 				(*dd_idx)++;
3156 			qd_idx = raid_disks - 1;
3157 			break;
3158 
3159 		case ALGORITHM_LEFT_SYMMETRIC_6:
3160 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
3161 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
3162 			qd_idx = raid_disks - 1;
3163 			break;
3164 
3165 		case ALGORITHM_RIGHT_SYMMETRIC_6:
3166 			pd_idx = sector_div(stripe2, raid_disks-1);
3167 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
3168 			qd_idx = raid_disks - 1;
3169 			break;
3170 
3171 		case ALGORITHM_PARITY_0_6:
3172 			pd_idx = 0;
3173 			(*dd_idx)++;
3174 			qd_idx = raid_disks - 1;
3175 			break;
3176 
3177 		default:
3178 			BUG();
3179 		}
3180 		break;
3181 	}
3182 
3183 	if (sh) {
3184 		sh->pd_idx = pd_idx;
3185 		sh->qd_idx = qd_idx;
3186 		sh->ddf_layout = ddf_layout;
3187 	}
3188 	/*
3189 	 * Finally, compute the new sector number
3190 	 */
3191 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
3192 	return new_sector;
3193 }
3194 
3195 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
3196 {
3197 	struct r5conf *conf = sh->raid_conf;
3198 	int raid_disks = sh->disks;
3199 	int data_disks = raid_disks - conf->max_degraded;
3200 	sector_t new_sector = sh->sector, check;
3201 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
3202 					 : conf->chunk_sectors;
3203 	int algorithm = previous ? conf->prev_algo
3204 				 : conf->algorithm;
3205 	sector_t stripe;
3206 	int chunk_offset;
3207 	sector_t chunk_number;
3208 	int dummy1, dd_idx = i;
3209 	sector_t r_sector;
3210 	struct stripe_head sh2;
3211 
3212 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
3213 	stripe = new_sector;
3214 
3215 	if (i == sh->pd_idx)
3216 		return 0;
3217 	switch(conf->level) {
3218 	case 4: break;
3219 	case 5:
3220 		switch (algorithm) {
3221 		case ALGORITHM_LEFT_ASYMMETRIC:
3222 		case ALGORITHM_RIGHT_ASYMMETRIC:
3223 			if (i > sh->pd_idx)
3224 				i--;
3225 			break;
3226 		case ALGORITHM_LEFT_SYMMETRIC:
3227 		case ALGORITHM_RIGHT_SYMMETRIC:
3228 			if (i < sh->pd_idx)
3229 				i += raid_disks;
3230 			i -= (sh->pd_idx + 1);
3231 			break;
3232 		case ALGORITHM_PARITY_0:
3233 			i -= 1;
3234 			break;
3235 		case ALGORITHM_PARITY_N:
3236 			break;
3237 		default:
3238 			BUG();
3239 		}
3240 		break;
3241 	case 6:
3242 		if (i == sh->qd_idx)
3243 			return 0; /* It is the Q disk */
3244 		switch (algorithm) {
3245 		case ALGORITHM_LEFT_ASYMMETRIC:
3246 		case ALGORITHM_RIGHT_ASYMMETRIC:
3247 		case ALGORITHM_ROTATING_ZERO_RESTART:
3248 		case ALGORITHM_ROTATING_N_RESTART:
3249 			if (sh->pd_idx == raid_disks-1)
3250 				i--;	/* Q D D D P */
3251 			else if (i > sh->pd_idx)
3252 				i -= 2; /* D D P Q D */
3253 			break;
3254 		case ALGORITHM_LEFT_SYMMETRIC:
3255 		case ALGORITHM_RIGHT_SYMMETRIC:
3256 			if (sh->pd_idx == raid_disks-1)
3257 				i--; /* Q D D D P */
3258 			else {
3259 				/* D D P Q D */
3260 				if (i < sh->pd_idx)
3261 					i += raid_disks;
3262 				i -= (sh->pd_idx + 2);
3263 			}
3264 			break;
3265 		case ALGORITHM_PARITY_0:
3266 			i -= 2;
3267 			break;
3268 		case ALGORITHM_PARITY_N:
3269 			break;
3270 		case ALGORITHM_ROTATING_N_CONTINUE:
3271 			/* Like left_symmetric, but P is before Q */
3272 			if (sh->pd_idx == 0)
3273 				i--;	/* P D D D Q */
3274 			else {
3275 				/* D D Q P D */
3276 				if (i < sh->pd_idx)
3277 					i += raid_disks;
3278 				i -= (sh->pd_idx + 1);
3279 			}
3280 			break;
3281 		case ALGORITHM_LEFT_ASYMMETRIC_6:
3282 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
3283 			if (i > sh->pd_idx)
3284 				i--;
3285 			break;
3286 		case ALGORITHM_LEFT_SYMMETRIC_6:
3287 		case ALGORITHM_RIGHT_SYMMETRIC_6:
3288 			if (i < sh->pd_idx)
3289 				i += data_disks + 1;
3290 			i -= (sh->pd_idx + 1);
3291 			break;
3292 		case ALGORITHM_PARITY_0_6:
3293 			i -= 1;
3294 			break;
3295 		default:
3296 			BUG();
3297 		}
3298 		break;
3299 	}
3300 
3301 	chunk_number = stripe * data_disks + i;
3302 	r_sector = chunk_number * sectors_per_chunk + chunk_offset;
3303 
3304 	check = raid5_compute_sector(conf, r_sector,
3305 				     previous, &dummy1, &sh2);
3306 	if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
3307 		|| sh2.qd_idx != sh->qd_idx) {
3308 		pr_warn("md/raid:%s: compute_blocknr: map not correct\n",
3309 			mdname(conf->mddev));
3310 		return 0;
3311 	}
3312 	return r_sector;
3313 }
3314 
3315 /*
3316  * There are cases where we want handle_stripe_dirtying() and
3317  * schedule_reconstruction() to delay towrite to some dev of a stripe.
3318  *
3319  * This function checks whether we want to delay the towrite. Specifically,
3320  * we delay the towrite when:
3321  *
3322  *   1. degraded stripe has a non-overwrite to the missing dev, AND this
3323  *      stripe has data in journal (for other devices).
3324  *
3325  *      In this case, when reading data for the non-overwrite dev, it is
3326  *      necessary to handle complex rmw of write back cache (prexor with
3327  *      orig_page, and xor with page). To keep read path simple, we would
3328  *      like to flush data in journal to RAID disks first, so complex rmw
3329  *      is handled in the write patch (handle_stripe_dirtying).
3330  *
3331  *   2. when journal space is critical (R5C_LOG_CRITICAL=1)
3332  *
3333  *      It is important to be able to flush all stripes in raid5-cache.
3334  *      Therefore, we need reserve some space on the journal device for
3335  *      these flushes. If flush operation includes pending writes to the
3336  *      stripe, we need to reserve (conf->raid_disk + 1) pages per stripe
3337  *      for the flush out. If we exclude these pending writes from flush
3338  *      operation, we only need (conf->max_degraded + 1) pages per stripe.
3339  *      Therefore, excluding pending writes in these cases enables more
3340  *      efficient use of the journal device.
3341  *
3342  *      Note: To make sure the stripe makes progress, we only delay
3343  *      towrite for stripes with data already in journal (injournal > 0).
3344  *      When LOG_CRITICAL, stripes with injournal == 0 will be sent to
3345  *      no_space_stripes list.
3346  *
3347  *   3. during journal failure
3348  *      In journal failure, we try to flush all cached data to raid disks
3349  *      based on data in stripe cache. The array is read-only to upper
3350  *      layers, so we would skip all pending writes.
3351  *
3352  */
3353 static inline bool delay_towrite(struct r5conf *conf,
3354 				 struct r5dev *dev,
3355 				 struct stripe_head_state *s)
3356 {
3357 	/* case 1 above */
3358 	if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3359 	    !test_bit(R5_Insync, &dev->flags) && s->injournal)
3360 		return true;
3361 	/* case 2 above */
3362 	if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
3363 	    s->injournal > 0)
3364 		return true;
3365 	/* case 3 above */
3366 	if (s->log_failed && s->injournal)
3367 		return true;
3368 	return false;
3369 }
3370 
3371 static void
3372 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
3373 			 int rcw, int expand)
3374 {
3375 	int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
3376 	struct r5conf *conf = sh->raid_conf;
3377 	int level = conf->level;
3378 
3379 	if (rcw) {
3380 		/*
3381 		 * In some cases, handle_stripe_dirtying initially decided to
3382 		 * run rmw and allocates extra page for prexor. However, rcw is
3383 		 * cheaper later on. We need to free the extra page now,
3384 		 * because we won't be able to do that in ops_complete_prexor().
3385 		 */
3386 		r5c_release_extra_page(sh);
3387 
3388 		for (i = disks; i--; ) {
3389 			struct r5dev *dev = &sh->dev[i];
3390 
3391 			if (dev->towrite && !delay_towrite(conf, dev, s)) {
3392 				set_bit(R5_LOCKED, &dev->flags);
3393 				set_bit(R5_Wantdrain, &dev->flags);
3394 				if (!expand)
3395 					clear_bit(R5_UPTODATE, &dev->flags);
3396 				s->locked++;
3397 			} else if (test_bit(R5_InJournal, &dev->flags)) {
3398 				set_bit(R5_LOCKED, &dev->flags);
3399 				s->locked++;
3400 			}
3401 		}
3402 		/* if we are not expanding this is a proper write request, and
3403 		 * there will be bios with new data to be drained into the
3404 		 * stripe cache
3405 		 */
3406 		if (!expand) {
3407 			if (!s->locked)
3408 				/* False alarm, nothing to do */
3409 				return;
3410 			sh->reconstruct_state = reconstruct_state_drain_run;
3411 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3412 		} else
3413 			sh->reconstruct_state = reconstruct_state_run;
3414 
3415 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3416 
3417 		if (s->locked + conf->max_degraded == disks)
3418 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
3419 				atomic_inc(&conf->pending_full_writes);
3420 	} else {
3421 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
3422 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
3423 		BUG_ON(level == 6 &&
3424 			(!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
3425 			   test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
3426 
3427 		for (i = disks; i--; ) {
3428 			struct r5dev *dev = &sh->dev[i];
3429 			if (i == pd_idx || i == qd_idx)
3430 				continue;
3431 
3432 			if (dev->towrite &&
3433 			    (test_bit(R5_UPTODATE, &dev->flags) ||
3434 			     test_bit(R5_Wantcompute, &dev->flags))) {
3435 				set_bit(R5_Wantdrain, &dev->flags);
3436 				set_bit(R5_LOCKED, &dev->flags);
3437 				clear_bit(R5_UPTODATE, &dev->flags);
3438 				s->locked++;
3439 			} else if (test_bit(R5_InJournal, &dev->flags)) {
3440 				set_bit(R5_LOCKED, &dev->flags);
3441 				s->locked++;
3442 			}
3443 		}
3444 		if (!s->locked)
3445 			/* False alarm - nothing to do */
3446 			return;
3447 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
3448 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
3449 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3450 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3451 	}
3452 
3453 	/* keep the parity disk(s) locked while asynchronous operations
3454 	 * are in flight
3455 	 */
3456 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
3457 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3458 	s->locked++;
3459 
3460 	if (level == 6) {
3461 		int qd_idx = sh->qd_idx;
3462 		struct r5dev *dev = &sh->dev[qd_idx];
3463 
3464 		set_bit(R5_LOCKED, &dev->flags);
3465 		clear_bit(R5_UPTODATE, &dev->flags);
3466 		s->locked++;
3467 	}
3468 
3469 	if (raid5_has_ppl(sh->raid_conf) && sh->ppl_page &&
3470 	    test_bit(STRIPE_OP_BIODRAIN, &s->ops_request) &&
3471 	    !test_bit(STRIPE_FULL_WRITE, &sh->state) &&
3472 	    test_bit(R5_Insync, &sh->dev[pd_idx].flags))
3473 		set_bit(STRIPE_OP_PARTIAL_PARITY, &s->ops_request);
3474 
3475 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
3476 		__func__, (unsigned long long)sh->sector,
3477 		s->locked, s->ops_request);
3478 }
3479 
3480 static bool stripe_bio_overlaps(struct stripe_head *sh, struct bio *bi,
3481 				int dd_idx, int forwrite)
3482 {
3483 	struct r5conf *conf = sh->raid_conf;
3484 	struct bio **bip;
3485 
3486 	pr_debug("checking bi b#%llu to stripe s#%llu\n",
3487 		 bi->bi_iter.bi_sector, sh->sector);
3488 
3489 	/* Don't allow new IO added to stripes in batch list */
3490 	if (sh->batch_head)
3491 		return true;
3492 
3493 	if (forwrite)
3494 		bip = &sh->dev[dd_idx].towrite;
3495 	else
3496 		bip = &sh->dev[dd_idx].toread;
3497 
3498 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
3499 		if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
3500 			return true;
3501 		bip = &(*bip)->bi_next;
3502 	}
3503 
3504 	if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
3505 		return true;
3506 
3507 	if (forwrite && raid5_has_ppl(conf)) {
3508 		/*
3509 		 * With PPL only writes to consecutive data chunks within a
3510 		 * stripe are allowed because for a single stripe_head we can
3511 		 * only have one PPL entry at a time, which describes one data
3512 		 * range. Not really an overlap, but wait_for_overlap can be
3513 		 * used to handle this.
3514 		 */
3515 		sector_t sector;
3516 		sector_t first = 0;
3517 		sector_t last = 0;
3518 		int count = 0;
3519 		int i;
3520 
3521 		for (i = 0; i < sh->disks; i++) {
3522 			if (i != sh->pd_idx &&
3523 			    (i == dd_idx || sh->dev[i].towrite)) {
3524 				sector = sh->dev[i].sector;
3525 				if (count == 0 || sector < first)
3526 					first = sector;
3527 				if (sector > last)
3528 					last = sector;
3529 				count++;
3530 			}
3531 		}
3532 
3533 		if (first + conf->chunk_sectors * (count - 1) != last)
3534 			return true;
3535 	}
3536 
3537 	return false;
3538 }
3539 
3540 static void __add_stripe_bio(struct stripe_head *sh, struct bio *bi,
3541 			     int dd_idx, int forwrite, int previous)
3542 {
3543 	struct r5conf *conf = sh->raid_conf;
3544 	struct bio **bip;
3545 	int firstwrite = 0;
3546 
3547 	if (forwrite) {
3548 		bip = &sh->dev[dd_idx].towrite;
3549 		if (!*bip)
3550 			firstwrite = 1;
3551 	} else {
3552 		bip = &sh->dev[dd_idx].toread;
3553 	}
3554 
3555 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector)
3556 		bip = &(*bip)->bi_next;
3557 
3558 	if (!forwrite || previous)
3559 		clear_bit(STRIPE_BATCH_READY, &sh->state);
3560 
3561 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3562 	if (*bip)
3563 		bi->bi_next = *bip;
3564 	*bip = bi;
3565 	bio_inc_remaining(bi);
3566 	md_write_inc(conf->mddev, bi);
3567 
3568 	if (forwrite) {
3569 		/* check if page is covered */
3570 		sector_t sector = sh->dev[dd_idx].sector;
3571 		for (bi=sh->dev[dd_idx].towrite;
3572 		     sector < sh->dev[dd_idx].sector + RAID5_STRIPE_SECTORS(conf) &&
3573 			     bi && bi->bi_iter.bi_sector <= sector;
3574 		     bi = r5_next_bio(conf, bi, sh->dev[dd_idx].sector)) {
3575 			if (bio_end_sector(bi) >= sector)
3576 				sector = bio_end_sector(bi);
3577 		}
3578 		if (sector >= sh->dev[dd_idx].sector + RAID5_STRIPE_SECTORS(conf))
3579 			if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3580 				sh->overwrite_disks++;
3581 	}
3582 
3583 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d, logical %llu\n",
3584 		 (*bip)->bi_iter.bi_sector, sh->sector, dd_idx,
3585 		 sh->dev[dd_idx].sector);
3586 
3587 	if (conf->mddev->bitmap && firstwrite) {
3588 		/* Cannot hold spinlock over bitmap_startwrite,
3589 		 * but must ensure this isn't added to a batch until
3590 		 * we have added to the bitmap and set bm_seq.
3591 		 * So set STRIPE_BITMAP_PENDING to prevent
3592 		 * batching.
3593 		 * If multiple __add_stripe_bio() calls race here they
3594 		 * much all set STRIPE_BITMAP_PENDING.  So only the first one
3595 		 * to complete "bitmap_startwrite" gets to set
3596 		 * STRIPE_BIT_DELAY.  This is important as once a stripe
3597 		 * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3598 		 * any more.
3599 		 */
3600 		set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3601 		spin_unlock_irq(&sh->stripe_lock);
3602 		md_bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3603 				     RAID5_STRIPE_SECTORS(conf), 0);
3604 		spin_lock_irq(&sh->stripe_lock);
3605 		clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3606 		if (!sh->batch_head) {
3607 			sh->bm_seq = conf->seq_flush+1;
3608 			set_bit(STRIPE_BIT_DELAY, &sh->state);
3609 		}
3610 	}
3611 }
3612 
3613 /*
3614  * Each stripe/dev can have one or more bios attached.
3615  * toread/towrite point to the first in a chain.
3616  * The bi_next chain must be in order.
3617  */
3618 static bool add_stripe_bio(struct stripe_head *sh, struct bio *bi,
3619 			   int dd_idx, int forwrite, int previous)
3620 {
3621 	spin_lock_irq(&sh->stripe_lock);
3622 
3623 	if (stripe_bio_overlaps(sh, bi, dd_idx, forwrite)) {
3624 		set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3625 		spin_unlock_irq(&sh->stripe_lock);
3626 		return false;
3627 	}
3628 
3629 	__add_stripe_bio(sh, bi, dd_idx, forwrite, previous);
3630 	spin_unlock_irq(&sh->stripe_lock);
3631 	return true;
3632 }
3633 
3634 static void end_reshape(struct r5conf *conf);
3635 
3636 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3637 			    struct stripe_head *sh)
3638 {
3639 	int sectors_per_chunk =
3640 		previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3641 	int dd_idx;
3642 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
3643 	int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3644 
3645 	raid5_compute_sector(conf,
3646 			     stripe * (disks - conf->max_degraded)
3647 			     *sectors_per_chunk + chunk_offset,
3648 			     previous,
3649 			     &dd_idx, sh);
3650 }
3651 
3652 static void
3653 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3654 		     struct stripe_head_state *s, int disks)
3655 {
3656 	int i;
3657 	BUG_ON(sh->batch_head);
3658 	for (i = disks; i--; ) {
3659 		struct bio *bi;
3660 		int bitmap_end = 0;
3661 
3662 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3663 			struct md_rdev *rdev;
3664 			rcu_read_lock();
3665 			rdev = rcu_dereference(conf->disks[i].rdev);
3666 			if (rdev && test_bit(In_sync, &rdev->flags) &&
3667 			    !test_bit(Faulty, &rdev->flags))
3668 				atomic_inc(&rdev->nr_pending);
3669 			else
3670 				rdev = NULL;
3671 			rcu_read_unlock();
3672 			if (rdev) {
3673 				if (!rdev_set_badblocks(
3674 					    rdev,
3675 					    sh->sector,
3676 					    RAID5_STRIPE_SECTORS(conf), 0))
3677 					md_error(conf->mddev, rdev);
3678 				rdev_dec_pending(rdev, conf->mddev);
3679 			}
3680 		}
3681 		spin_lock_irq(&sh->stripe_lock);
3682 		/* fail all writes first */
3683 		bi = sh->dev[i].towrite;
3684 		sh->dev[i].towrite = NULL;
3685 		sh->overwrite_disks = 0;
3686 		spin_unlock_irq(&sh->stripe_lock);
3687 		if (bi)
3688 			bitmap_end = 1;
3689 
3690 		log_stripe_write_finished(sh);
3691 
3692 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3693 			wake_up(&conf->wait_for_overlap);
3694 
3695 		while (bi && bi->bi_iter.bi_sector <
3696 			sh->dev[i].sector + RAID5_STRIPE_SECTORS(conf)) {
3697 			struct bio *nextbi = r5_next_bio(conf, bi, sh->dev[i].sector);
3698 
3699 			md_write_end(conf->mddev);
3700 			bio_io_error(bi);
3701 			bi = nextbi;
3702 		}
3703 		if (bitmap_end)
3704 			md_bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3705 					   RAID5_STRIPE_SECTORS(conf), 0, 0);
3706 		bitmap_end = 0;
3707 		/* and fail all 'written' */
3708 		bi = sh->dev[i].written;
3709 		sh->dev[i].written = NULL;
3710 		if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3711 			WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3712 			sh->dev[i].page = sh->dev[i].orig_page;
3713 		}
3714 
3715 		if (bi) bitmap_end = 1;
3716 		while (bi && bi->bi_iter.bi_sector <
3717 		       sh->dev[i].sector + RAID5_STRIPE_SECTORS(conf)) {
3718 			struct bio *bi2 = r5_next_bio(conf, bi, sh->dev[i].sector);
3719 
3720 			md_write_end(conf->mddev);
3721 			bio_io_error(bi);
3722 			bi = bi2;
3723 		}
3724 
3725 		/* fail any reads if this device is non-operational and
3726 		 * the data has not reached the cache yet.
3727 		 */
3728 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3729 		    s->failed > conf->max_degraded &&
3730 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3731 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
3732 			spin_lock_irq(&sh->stripe_lock);
3733 			bi = sh->dev[i].toread;
3734 			sh->dev[i].toread = NULL;
3735 			spin_unlock_irq(&sh->stripe_lock);
3736 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3737 				wake_up(&conf->wait_for_overlap);
3738 			if (bi)
3739 				s->to_read--;
3740 			while (bi && bi->bi_iter.bi_sector <
3741 			       sh->dev[i].sector + RAID5_STRIPE_SECTORS(conf)) {
3742 				struct bio *nextbi =
3743 					r5_next_bio(conf, bi, sh->dev[i].sector);
3744 
3745 				bio_io_error(bi);
3746 				bi = nextbi;
3747 			}
3748 		}
3749 		if (bitmap_end)
3750 			md_bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3751 					   RAID5_STRIPE_SECTORS(conf), 0, 0);
3752 		/* If we were in the middle of a write the parity block might
3753 		 * still be locked - so just clear all R5_LOCKED flags
3754 		 */
3755 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
3756 	}
3757 	s->to_write = 0;
3758 	s->written = 0;
3759 
3760 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3761 		if (atomic_dec_and_test(&conf->pending_full_writes))
3762 			md_wakeup_thread(conf->mddev->thread);
3763 }
3764 
3765 static void
3766 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3767 		   struct stripe_head_state *s)
3768 {
3769 	int abort = 0;
3770 	int i;
3771 
3772 	BUG_ON(sh->batch_head);
3773 	clear_bit(STRIPE_SYNCING, &sh->state);
3774 	if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3775 		wake_up(&conf->wait_for_overlap);
3776 	s->syncing = 0;
3777 	s->replacing = 0;
3778 	/* There is nothing more to do for sync/check/repair.
3779 	 * Don't even need to abort as that is handled elsewhere
3780 	 * if needed, and not always wanted e.g. if there is a known
3781 	 * bad block here.
3782 	 * For recover/replace we need to record a bad block on all
3783 	 * non-sync devices, or abort the recovery
3784 	 */
3785 	if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3786 		/* During recovery devices cannot be removed, so
3787 		 * locking and refcounting of rdevs is not needed
3788 		 */
3789 		rcu_read_lock();
3790 		for (i = 0; i < conf->raid_disks; i++) {
3791 			struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
3792 			if (rdev
3793 			    && !test_bit(Faulty, &rdev->flags)
3794 			    && !test_bit(In_sync, &rdev->flags)
3795 			    && !rdev_set_badblocks(rdev, sh->sector,
3796 						   RAID5_STRIPE_SECTORS(conf), 0))
3797 				abort = 1;
3798 			rdev = rcu_dereference(conf->disks[i].replacement);
3799 			if (rdev
3800 			    && !test_bit(Faulty, &rdev->flags)
3801 			    && !test_bit(In_sync, &rdev->flags)
3802 			    && !rdev_set_badblocks(rdev, sh->sector,
3803 						   RAID5_STRIPE_SECTORS(conf), 0))
3804 				abort = 1;
3805 		}
3806 		rcu_read_unlock();
3807 		if (abort)
3808 			conf->recovery_disabled =
3809 				conf->mddev->recovery_disabled;
3810 	}
3811 	md_done_sync(conf->mddev, RAID5_STRIPE_SECTORS(conf), !abort);
3812 }
3813 
3814 static int want_replace(struct stripe_head *sh, int disk_idx)
3815 {
3816 	struct md_rdev *rdev;
3817 	int rv = 0;
3818 
3819 	rcu_read_lock();
3820 	rdev = rcu_dereference(sh->raid_conf->disks[disk_idx].replacement);
3821 	if (rdev
3822 	    && !test_bit(Faulty, &rdev->flags)
3823 	    && !test_bit(In_sync, &rdev->flags)
3824 	    && (rdev->recovery_offset <= sh->sector
3825 		|| rdev->mddev->recovery_cp <= sh->sector))
3826 		rv = 1;
3827 	rcu_read_unlock();
3828 	return rv;
3829 }
3830 
3831 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3832 			   int disk_idx, int disks)
3833 {
3834 	struct r5dev *dev = &sh->dev[disk_idx];
3835 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3836 				  &sh->dev[s->failed_num[1]] };
3837 	int i;
3838 	bool force_rcw = (sh->raid_conf->rmw_level == PARITY_DISABLE_RMW);
3839 
3840 
3841 	if (test_bit(R5_LOCKED, &dev->flags) ||
3842 	    test_bit(R5_UPTODATE, &dev->flags))
3843 		/* No point reading this as we already have it or have
3844 		 * decided to get it.
3845 		 */
3846 		return 0;
3847 
3848 	if (dev->toread ||
3849 	    (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3850 		/* We need this block to directly satisfy a request */
3851 		return 1;
3852 
3853 	if (s->syncing || s->expanding ||
3854 	    (s->replacing && want_replace(sh, disk_idx)))
3855 		/* When syncing, or expanding we read everything.
3856 		 * When replacing, we need the replaced block.
3857 		 */
3858 		return 1;
3859 
3860 	if ((s->failed >= 1 && fdev[0]->toread) ||
3861 	    (s->failed >= 2 && fdev[1]->toread))
3862 		/* If we want to read from a failed device, then
3863 		 * we need to actually read every other device.
3864 		 */
3865 		return 1;
3866 
3867 	/* Sometimes neither read-modify-write nor reconstruct-write
3868 	 * cycles can work.  In those cases we read every block we
3869 	 * can.  Then the parity-update is certain to have enough to
3870 	 * work with.
3871 	 * This can only be a problem when we need to write something,
3872 	 * and some device has failed.  If either of those tests
3873 	 * fail we need look no further.
3874 	 */
3875 	if (!s->failed || !s->to_write)
3876 		return 0;
3877 
3878 	if (test_bit(R5_Insync, &dev->flags) &&
3879 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3880 		/* Pre-reads at not permitted until after short delay
3881 		 * to gather multiple requests.  However if this
3882 		 * device is no Insync, the block could only be computed
3883 		 * and there is no need to delay that.
3884 		 */
3885 		return 0;
3886 
3887 	for (i = 0; i < s->failed && i < 2; i++) {
3888 		if (fdev[i]->towrite &&
3889 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3890 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3891 			/* If we have a partial write to a failed
3892 			 * device, then we will need to reconstruct
3893 			 * the content of that device, so all other
3894 			 * devices must be read.
3895 			 */
3896 			return 1;
3897 
3898 		if (s->failed >= 2 &&
3899 		    (fdev[i]->towrite ||
3900 		     s->failed_num[i] == sh->pd_idx ||
3901 		     s->failed_num[i] == sh->qd_idx) &&
3902 		    !test_bit(R5_UPTODATE, &fdev[i]->flags))
3903 			/* In max degraded raid6, If the failed disk is P, Q,
3904 			 * or we want to read the failed disk, we need to do
3905 			 * reconstruct-write.
3906 			 */
3907 			force_rcw = true;
3908 	}
3909 
3910 	/* If we are forced to do a reconstruct-write, because parity
3911 	 * cannot be trusted and we are currently recovering it, there
3912 	 * is extra need to be careful.
3913 	 * If one of the devices that we would need to read, because
3914 	 * it is not being overwritten (and maybe not written at all)
3915 	 * is missing/faulty, then we need to read everything we can.
3916 	 */
3917 	if (!force_rcw &&
3918 	    sh->sector < sh->raid_conf->mddev->recovery_cp)
3919 		/* reconstruct-write isn't being forced */
3920 		return 0;
3921 	for (i = 0; i < s->failed && i < 2; i++) {
3922 		if (s->failed_num[i] != sh->pd_idx &&
3923 		    s->failed_num[i] != sh->qd_idx &&
3924 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3925 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3926 			return 1;
3927 	}
3928 
3929 	return 0;
3930 }
3931 
3932 /* fetch_block - checks the given member device to see if its data needs
3933  * to be read or computed to satisfy a request.
3934  *
3935  * Returns 1 when no more member devices need to be checked, otherwise returns
3936  * 0 to tell the loop in handle_stripe_fill to continue
3937  */
3938 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3939 		       int disk_idx, int disks)
3940 {
3941 	struct r5dev *dev = &sh->dev[disk_idx];
3942 
3943 	/* is the data in this block needed, and can we get it? */
3944 	if (need_this_block(sh, s, disk_idx, disks)) {
3945 		/* we would like to get this block, possibly by computing it,
3946 		 * otherwise read it if the backing disk is insync
3947 		 */
3948 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3949 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
3950 		BUG_ON(sh->batch_head);
3951 
3952 		/*
3953 		 * In the raid6 case if the only non-uptodate disk is P
3954 		 * then we already trusted P to compute the other failed
3955 		 * drives. It is safe to compute rather than re-read P.
3956 		 * In other cases we only compute blocks from failed
3957 		 * devices, otherwise check/repair might fail to detect
3958 		 * a real inconsistency.
3959 		 */
3960 
3961 		if ((s->uptodate == disks - 1) &&
3962 		    ((sh->qd_idx >= 0 && sh->pd_idx == disk_idx) ||
3963 		    (s->failed && (disk_idx == s->failed_num[0] ||
3964 				   disk_idx == s->failed_num[1])))) {
3965 			/* have disk failed, and we're requested to fetch it;
3966 			 * do compute it
3967 			 */
3968 			pr_debug("Computing stripe %llu block %d\n",
3969 			       (unsigned long long)sh->sector, disk_idx);
3970 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3971 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3972 			set_bit(R5_Wantcompute, &dev->flags);
3973 			sh->ops.target = disk_idx;
3974 			sh->ops.target2 = -1; /* no 2nd target */
3975 			s->req_compute = 1;
3976 			/* Careful: from this point on 'uptodate' is in the eye
3977 			 * of raid_run_ops which services 'compute' operations
3978 			 * before writes. R5_Wantcompute flags a block that will
3979 			 * be R5_UPTODATE by the time it is needed for a
3980 			 * subsequent operation.
3981 			 */
3982 			s->uptodate++;
3983 			return 1;
3984 		} else if (s->uptodate == disks-2 && s->failed >= 2) {
3985 			/* Computing 2-failure is *very* expensive; only
3986 			 * do it if failed >= 2
3987 			 */
3988 			int other;
3989 			for (other = disks; other--; ) {
3990 				if (other == disk_idx)
3991 					continue;
3992 				if (!test_bit(R5_UPTODATE,
3993 				      &sh->dev[other].flags))
3994 					break;
3995 			}
3996 			BUG_ON(other < 0);
3997 			pr_debug("Computing stripe %llu blocks %d,%d\n",
3998 			       (unsigned long long)sh->sector,
3999 			       disk_idx, other);
4000 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4001 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4002 			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
4003 			set_bit(R5_Wantcompute, &sh->dev[other].flags);
4004 			sh->ops.target = disk_idx;
4005 			sh->ops.target2 = other;
4006 			s->uptodate += 2;
4007 			s->req_compute = 1;
4008 			return 1;
4009 		} else if (test_bit(R5_Insync, &dev->flags)) {
4010 			set_bit(R5_LOCKED, &dev->flags);
4011 			set_bit(R5_Wantread, &dev->flags);
4012 			s->locked++;
4013 			pr_debug("Reading block %d (sync=%d)\n",
4014 				disk_idx, s->syncing);
4015 		}
4016 	}
4017 
4018 	return 0;
4019 }
4020 
4021 /*
4022  * handle_stripe_fill - read or compute data to satisfy pending requests.
4023  */
4024 static void handle_stripe_fill(struct stripe_head *sh,
4025 			       struct stripe_head_state *s,
4026 			       int disks)
4027 {
4028 	int i;
4029 
4030 	/* look for blocks to read/compute, skip this if a compute
4031 	 * is already in flight, or if the stripe contents are in the
4032 	 * midst of changing due to a write
4033 	 */
4034 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
4035 	    !sh->reconstruct_state) {
4036 
4037 		/*
4038 		 * For degraded stripe with data in journal, do not handle
4039 		 * read requests yet, instead, flush the stripe to raid
4040 		 * disks first, this avoids handling complex rmw of write
4041 		 * back cache (prexor with orig_page, and then xor with
4042 		 * page) in the read path
4043 		 */
4044 		if (s->to_read && s->injournal && s->failed) {
4045 			if (test_bit(STRIPE_R5C_CACHING, &sh->state))
4046 				r5c_make_stripe_write_out(sh);
4047 			goto out;
4048 		}
4049 
4050 		for (i = disks; i--; )
4051 			if (fetch_block(sh, s, i, disks))
4052 				break;
4053 	}
4054 out:
4055 	set_bit(STRIPE_HANDLE, &sh->state);
4056 }
4057 
4058 static void break_stripe_batch_list(struct stripe_head *head_sh,
4059 				    unsigned long handle_flags);
4060 /* handle_stripe_clean_event
4061  * any written block on an uptodate or failed drive can be returned.
4062  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
4063  * never LOCKED, so we don't need to test 'failed' directly.
4064  */
4065 static void handle_stripe_clean_event(struct r5conf *conf,
4066 	struct stripe_head *sh, int disks)
4067 {
4068 	int i;
4069 	struct r5dev *dev;
4070 	int discard_pending = 0;
4071 	struct stripe_head *head_sh = sh;
4072 	bool do_endio = false;
4073 
4074 	for (i = disks; i--; )
4075 		if (sh->dev[i].written) {
4076 			dev = &sh->dev[i];
4077 			if (!test_bit(R5_LOCKED, &dev->flags) &&
4078 			    (test_bit(R5_UPTODATE, &dev->flags) ||
4079 			     test_bit(R5_Discard, &dev->flags) ||
4080 			     test_bit(R5_SkipCopy, &dev->flags))) {
4081 				/* We can return any write requests */
4082 				struct bio *wbi, *wbi2;
4083 				pr_debug("Return write for disc %d\n", i);
4084 				if (test_and_clear_bit(R5_Discard, &dev->flags))
4085 					clear_bit(R5_UPTODATE, &dev->flags);
4086 				if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
4087 					WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
4088 				}
4089 				do_endio = true;
4090 
4091 returnbi:
4092 				dev->page = dev->orig_page;
4093 				wbi = dev->written;
4094 				dev->written = NULL;
4095 				while (wbi && wbi->bi_iter.bi_sector <
4096 					dev->sector + RAID5_STRIPE_SECTORS(conf)) {
4097 					wbi2 = r5_next_bio(conf, wbi, dev->sector);
4098 					md_write_end(conf->mddev);
4099 					bio_endio(wbi);
4100 					wbi = wbi2;
4101 				}
4102 				md_bitmap_endwrite(conf->mddev->bitmap, sh->sector,
4103 						   RAID5_STRIPE_SECTORS(conf),
4104 						   !test_bit(STRIPE_DEGRADED, &sh->state),
4105 						   0);
4106 				if (head_sh->batch_head) {
4107 					sh = list_first_entry(&sh->batch_list,
4108 							      struct stripe_head,
4109 							      batch_list);
4110 					if (sh != head_sh) {
4111 						dev = &sh->dev[i];
4112 						goto returnbi;
4113 					}
4114 				}
4115 				sh = head_sh;
4116 				dev = &sh->dev[i];
4117 			} else if (test_bit(R5_Discard, &dev->flags))
4118 				discard_pending = 1;
4119 		}
4120 
4121 	log_stripe_write_finished(sh);
4122 
4123 	if (!discard_pending &&
4124 	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
4125 		int hash;
4126 		clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
4127 		clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
4128 		if (sh->qd_idx >= 0) {
4129 			clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
4130 			clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
4131 		}
4132 		/* now that discard is done we can proceed with any sync */
4133 		clear_bit(STRIPE_DISCARD, &sh->state);
4134 		/*
4135 		 * SCSI discard will change some bio fields and the stripe has
4136 		 * no updated data, so remove it from hash list and the stripe
4137 		 * will be reinitialized
4138 		 */
4139 unhash:
4140 		hash = sh->hash_lock_index;
4141 		spin_lock_irq(conf->hash_locks + hash);
4142 		remove_hash(sh);
4143 		spin_unlock_irq(conf->hash_locks + hash);
4144 		if (head_sh->batch_head) {
4145 			sh = list_first_entry(&sh->batch_list,
4146 					      struct stripe_head, batch_list);
4147 			if (sh != head_sh)
4148 					goto unhash;
4149 		}
4150 		sh = head_sh;
4151 
4152 		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
4153 			set_bit(STRIPE_HANDLE, &sh->state);
4154 
4155 	}
4156 
4157 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
4158 		if (atomic_dec_and_test(&conf->pending_full_writes))
4159 			md_wakeup_thread(conf->mddev->thread);
4160 
4161 	if (head_sh->batch_head && do_endio)
4162 		break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
4163 }
4164 
4165 /*
4166  * For RMW in write back cache, we need extra page in prexor to store the
4167  * old data. This page is stored in dev->orig_page.
4168  *
4169  * This function checks whether we have data for prexor. The exact logic
4170  * is:
4171  *       R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
4172  */
4173 static inline bool uptodate_for_rmw(struct r5dev *dev)
4174 {
4175 	return (test_bit(R5_UPTODATE, &dev->flags)) &&
4176 		(!test_bit(R5_InJournal, &dev->flags) ||
4177 		 test_bit(R5_OrigPageUPTDODATE, &dev->flags));
4178 }
4179 
4180 static int handle_stripe_dirtying(struct r5conf *conf,
4181 				  struct stripe_head *sh,
4182 				  struct stripe_head_state *s,
4183 				  int disks)
4184 {
4185 	int rmw = 0, rcw = 0, i;
4186 	sector_t recovery_cp = conf->mddev->recovery_cp;
4187 
4188 	/* Check whether resync is now happening or should start.
4189 	 * If yes, then the array is dirty (after unclean shutdown or
4190 	 * initial creation), so parity in some stripes might be inconsistent.
4191 	 * In this case, we need to always do reconstruct-write, to ensure
4192 	 * that in case of drive failure or read-error correction, we
4193 	 * generate correct data from the parity.
4194 	 */
4195 	if (conf->rmw_level == PARITY_DISABLE_RMW ||
4196 	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
4197 	     s->failed == 0)) {
4198 		/* Calculate the real rcw later - for now make it
4199 		 * look like rcw is cheaper
4200 		 */
4201 		rcw = 1; rmw = 2;
4202 		pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
4203 			 conf->rmw_level, (unsigned long long)recovery_cp,
4204 			 (unsigned long long)sh->sector);
4205 	} else for (i = disks; i--; ) {
4206 		/* would I have to read this buffer for read_modify_write */
4207 		struct r5dev *dev = &sh->dev[i];
4208 		if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
4209 		     i == sh->pd_idx || i == sh->qd_idx ||
4210 		     test_bit(R5_InJournal, &dev->flags)) &&
4211 		    !test_bit(R5_LOCKED, &dev->flags) &&
4212 		    !(uptodate_for_rmw(dev) ||
4213 		      test_bit(R5_Wantcompute, &dev->flags))) {
4214 			if (test_bit(R5_Insync, &dev->flags))
4215 				rmw++;
4216 			else
4217 				rmw += 2*disks;  /* cannot read it */
4218 		}
4219 		/* Would I have to read this buffer for reconstruct_write */
4220 		if (!test_bit(R5_OVERWRITE, &dev->flags) &&
4221 		    i != sh->pd_idx && i != sh->qd_idx &&
4222 		    !test_bit(R5_LOCKED, &dev->flags) &&
4223 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
4224 		      test_bit(R5_Wantcompute, &dev->flags))) {
4225 			if (test_bit(R5_Insync, &dev->flags))
4226 				rcw++;
4227 			else
4228 				rcw += 2*disks;
4229 		}
4230 	}
4231 
4232 	pr_debug("for sector %llu state 0x%lx, rmw=%d rcw=%d\n",
4233 		 (unsigned long long)sh->sector, sh->state, rmw, rcw);
4234 	set_bit(STRIPE_HANDLE, &sh->state);
4235 	if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
4236 		/* prefer read-modify-write, but need to get some data */
4237 		if (conf->mddev->queue)
4238 			blk_add_trace_msg(conf->mddev->queue,
4239 					  "raid5 rmw %llu %d",
4240 					  (unsigned long long)sh->sector, rmw);
4241 		for (i = disks; i--; ) {
4242 			struct r5dev *dev = &sh->dev[i];
4243 			if (test_bit(R5_InJournal, &dev->flags) &&
4244 			    dev->page == dev->orig_page &&
4245 			    !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {
4246 				/* alloc page for prexor */
4247 				struct page *p = alloc_page(GFP_NOIO);
4248 
4249 				if (p) {
4250 					dev->orig_page = p;
4251 					continue;
4252 				}
4253 
4254 				/*
4255 				 * alloc_page() failed, try use
4256 				 * disk_info->extra_page
4257 				 */
4258 				if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,
4259 						      &conf->cache_state)) {
4260 					r5c_use_extra_page(sh);
4261 					break;
4262 				}
4263 
4264 				/* extra_page in use, add to delayed_list */
4265 				set_bit(STRIPE_DELAYED, &sh->state);
4266 				s->waiting_extra_page = 1;
4267 				return -EAGAIN;
4268 			}
4269 		}
4270 
4271 		for (i = disks; i--; ) {
4272 			struct r5dev *dev = &sh->dev[i];
4273 			if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
4274 			     i == sh->pd_idx || i == sh->qd_idx ||
4275 			     test_bit(R5_InJournal, &dev->flags)) &&
4276 			    !test_bit(R5_LOCKED, &dev->flags) &&
4277 			    !(uptodate_for_rmw(dev) ||
4278 			      test_bit(R5_Wantcompute, &dev->flags)) &&
4279 			    test_bit(R5_Insync, &dev->flags)) {
4280 				if (test_bit(STRIPE_PREREAD_ACTIVE,
4281 					     &sh->state)) {
4282 					pr_debug("Read_old block %d for r-m-w\n",
4283 						 i);
4284 					set_bit(R5_LOCKED, &dev->flags);
4285 					set_bit(R5_Wantread, &dev->flags);
4286 					s->locked++;
4287 				} else
4288 					set_bit(STRIPE_DELAYED, &sh->state);
4289 			}
4290 		}
4291 	}
4292 	if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
4293 		/* want reconstruct write, but need to get some data */
4294 		int qread =0;
4295 		rcw = 0;
4296 		for (i = disks; i--; ) {
4297 			struct r5dev *dev = &sh->dev[i];
4298 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
4299 			    i != sh->pd_idx && i != sh->qd_idx &&
4300 			    !test_bit(R5_LOCKED, &dev->flags) &&
4301 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
4302 			      test_bit(R5_Wantcompute, &dev->flags))) {
4303 				rcw++;
4304 				if (test_bit(R5_Insync, &dev->flags) &&
4305 				    test_bit(STRIPE_PREREAD_ACTIVE,
4306 					     &sh->state)) {
4307 					pr_debug("Read_old block "
4308 						"%d for Reconstruct\n", i);
4309 					set_bit(R5_LOCKED, &dev->flags);
4310 					set_bit(R5_Wantread, &dev->flags);
4311 					s->locked++;
4312 					qread++;
4313 				} else
4314 					set_bit(STRIPE_DELAYED, &sh->state);
4315 			}
4316 		}
4317 		if (rcw && conf->mddev->queue)
4318 			blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
4319 					  (unsigned long long)sh->sector,
4320 					  rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
4321 	}
4322 
4323 	if (rcw > disks && rmw > disks &&
4324 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4325 		set_bit(STRIPE_DELAYED, &sh->state);
4326 
4327 	/* now if nothing is locked, and if we have enough data,
4328 	 * we can start a write request
4329 	 */
4330 	/* since handle_stripe can be called at any time we need to handle the
4331 	 * case where a compute block operation has been submitted and then a
4332 	 * subsequent call wants to start a write request.  raid_run_ops only
4333 	 * handles the case where compute block and reconstruct are requested
4334 	 * simultaneously.  If this is not the case then new writes need to be
4335 	 * held off until the compute completes.
4336 	 */
4337 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
4338 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
4339 	     !test_bit(STRIPE_BIT_DELAY, &sh->state)))
4340 		schedule_reconstruction(sh, s, rcw == 0, 0);
4341 	return 0;
4342 }
4343 
4344 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
4345 				struct stripe_head_state *s, int disks)
4346 {
4347 	struct r5dev *dev = NULL;
4348 
4349 	BUG_ON(sh->batch_head);
4350 	set_bit(STRIPE_HANDLE, &sh->state);
4351 
4352 	switch (sh->check_state) {
4353 	case check_state_idle:
4354 		/* start a new check operation if there are no failures */
4355 		if (s->failed == 0) {
4356 			BUG_ON(s->uptodate != disks);
4357 			sh->check_state = check_state_run;
4358 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
4359 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
4360 			s->uptodate--;
4361 			break;
4362 		}
4363 		dev = &sh->dev[s->failed_num[0]];
4364 		fallthrough;
4365 	case check_state_compute_result:
4366 		sh->check_state = check_state_idle;
4367 		if (!dev)
4368 			dev = &sh->dev[sh->pd_idx];
4369 
4370 		/* check that a write has not made the stripe insync */
4371 		if (test_bit(STRIPE_INSYNC, &sh->state))
4372 			break;
4373 
4374 		/* either failed parity check, or recovery is happening */
4375 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
4376 		BUG_ON(s->uptodate != disks);
4377 
4378 		set_bit(R5_LOCKED, &dev->flags);
4379 		s->locked++;
4380 		set_bit(R5_Wantwrite, &dev->flags);
4381 
4382 		clear_bit(STRIPE_DEGRADED, &sh->state);
4383 		set_bit(STRIPE_INSYNC, &sh->state);
4384 		break;
4385 	case check_state_run:
4386 		break; /* we will be called again upon completion */
4387 	case check_state_check_result:
4388 		sh->check_state = check_state_idle;
4389 
4390 		/* if a failure occurred during the check operation, leave
4391 		 * STRIPE_INSYNC not set and let the stripe be handled again
4392 		 */
4393 		if (s->failed)
4394 			break;
4395 
4396 		/* handle a successful check operation, if parity is correct
4397 		 * we are done.  Otherwise update the mismatch count and repair
4398 		 * parity if !MD_RECOVERY_CHECK
4399 		 */
4400 		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
4401 			/* parity is correct (on disc,
4402 			 * not in buffer any more)
4403 			 */
4404 			set_bit(STRIPE_INSYNC, &sh->state);
4405 		else {
4406 			atomic64_add(RAID5_STRIPE_SECTORS(conf), &conf->mddev->resync_mismatches);
4407 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery)) {
4408 				/* don't try to repair!! */
4409 				set_bit(STRIPE_INSYNC, &sh->state);
4410 				pr_warn_ratelimited("%s: mismatch sector in range "
4411 						    "%llu-%llu\n", mdname(conf->mddev),
4412 						    (unsigned long long) sh->sector,
4413 						    (unsigned long long) sh->sector +
4414 						    RAID5_STRIPE_SECTORS(conf));
4415 			} else {
4416 				sh->check_state = check_state_compute_run;
4417 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4418 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4419 				set_bit(R5_Wantcompute,
4420 					&sh->dev[sh->pd_idx].flags);
4421 				sh->ops.target = sh->pd_idx;
4422 				sh->ops.target2 = -1;
4423 				s->uptodate++;
4424 			}
4425 		}
4426 		break;
4427 	case check_state_compute_run:
4428 		break;
4429 	default:
4430 		pr_err("%s: unknown check_state: %d sector: %llu\n",
4431 		       __func__, sh->check_state,
4432 		       (unsigned long long) sh->sector);
4433 		BUG();
4434 	}
4435 }
4436 
4437 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
4438 				  struct stripe_head_state *s,
4439 				  int disks)
4440 {
4441 	int pd_idx = sh->pd_idx;
4442 	int qd_idx = sh->qd_idx;
4443 	struct r5dev *dev;
4444 
4445 	BUG_ON(sh->batch_head);
4446 	set_bit(STRIPE_HANDLE, &sh->state);
4447 
4448 	BUG_ON(s->failed > 2);
4449 
4450 	/* Want to check and possibly repair P and Q.
4451 	 * However there could be one 'failed' device, in which
4452 	 * case we can only check one of them, possibly using the
4453 	 * other to generate missing data
4454 	 */
4455 
4456 	switch (sh->check_state) {
4457 	case check_state_idle:
4458 		/* start a new check operation if there are < 2 failures */
4459 		if (s->failed == s->q_failed) {
4460 			/* The only possible failed device holds Q, so it
4461 			 * makes sense to check P (If anything else were failed,
4462 			 * we would have used P to recreate it).
4463 			 */
4464 			sh->check_state = check_state_run;
4465 		}
4466 		if (!s->q_failed && s->failed < 2) {
4467 			/* Q is not failed, and we didn't use it to generate
4468 			 * anything, so it makes sense to check it
4469 			 */
4470 			if (sh->check_state == check_state_run)
4471 				sh->check_state = check_state_run_pq;
4472 			else
4473 				sh->check_state = check_state_run_q;
4474 		}
4475 
4476 		/* discard potentially stale zero_sum_result */
4477 		sh->ops.zero_sum_result = 0;
4478 
4479 		if (sh->check_state == check_state_run) {
4480 			/* async_xor_zero_sum destroys the contents of P */
4481 			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
4482 			s->uptodate--;
4483 		}
4484 		if (sh->check_state >= check_state_run &&
4485 		    sh->check_state <= check_state_run_pq) {
4486 			/* async_syndrome_zero_sum preserves P and Q, so
4487 			 * no need to mark them !uptodate here
4488 			 */
4489 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
4490 			break;
4491 		}
4492 
4493 		/* we have 2-disk failure */
4494 		BUG_ON(s->failed != 2);
4495 		fallthrough;
4496 	case check_state_compute_result:
4497 		sh->check_state = check_state_idle;
4498 
4499 		/* check that a write has not made the stripe insync */
4500 		if (test_bit(STRIPE_INSYNC, &sh->state))
4501 			break;
4502 
4503 		/* now write out any block on a failed drive,
4504 		 * or P or Q if they were recomputed
4505 		 */
4506 		dev = NULL;
4507 		if (s->failed == 2) {
4508 			dev = &sh->dev[s->failed_num[1]];
4509 			s->locked++;
4510 			set_bit(R5_LOCKED, &dev->flags);
4511 			set_bit(R5_Wantwrite, &dev->flags);
4512 		}
4513 		if (s->failed >= 1) {
4514 			dev = &sh->dev[s->failed_num[0]];
4515 			s->locked++;
4516 			set_bit(R5_LOCKED, &dev->flags);
4517 			set_bit(R5_Wantwrite, &dev->flags);
4518 		}
4519 		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4520 			dev = &sh->dev[pd_idx];
4521 			s->locked++;
4522 			set_bit(R5_LOCKED, &dev->flags);
4523 			set_bit(R5_Wantwrite, &dev->flags);
4524 		}
4525 		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4526 			dev = &sh->dev[qd_idx];
4527 			s->locked++;
4528 			set_bit(R5_LOCKED, &dev->flags);
4529 			set_bit(R5_Wantwrite, &dev->flags);
4530 		}
4531 		if (WARN_ONCE(dev && !test_bit(R5_UPTODATE, &dev->flags),
4532 			      "%s: disk%td not up to date\n",
4533 			      mdname(conf->mddev),
4534 			      dev - (struct r5dev *) &sh->dev)) {
4535 			clear_bit(R5_LOCKED, &dev->flags);
4536 			clear_bit(R5_Wantwrite, &dev->flags);
4537 			s->locked--;
4538 		}
4539 		clear_bit(STRIPE_DEGRADED, &sh->state);
4540 
4541 		set_bit(STRIPE_INSYNC, &sh->state);
4542 		break;
4543 	case check_state_run:
4544 	case check_state_run_q:
4545 	case check_state_run_pq:
4546 		break; /* we will be called again upon completion */
4547 	case check_state_check_result:
4548 		sh->check_state = check_state_idle;
4549 
4550 		/* handle a successful check operation, if parity is correct
4551 		 * we are done.  Otherwise update the mismatch count and repair
4552 		 * parity if !MD_RECOVERY_CHECK
4553 		 */
4554 		if (sh->ops.zero_sum_result == 0) {
4555 			/* both parities are correct */
4556 			if (!s->failed)
4557 				set_bit(STRIPE_INSYNC, &sh->state);
4558 			else {
4559 				/* in contrast to the raid5 case we can validate
4560 				 * parity, but still have a failure to write
4561 				 * back
4562 				 */
4563 				sh->check_state = check_state_compute_result;
4564 				/* Returning at this point means that we may go
4565 				 * off and bring p and/or q uptodate again so
4566 				 * we make sure to check zero_sum_result again
4567 				 * to verify if p or q need writeback
4568 				 */
4569 			}
4570 		} else {
4571 			atomic64_add(RAID5_STRIPE_SECTORS(conf), &conf->mddev->resync_mismatches);
4572 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery)) {
4573 				/* don't try to repair!! */
4574 				set_bit(STRIPE_INSYNC, &sh->state);
4575 				pr_warn_ratelimited("%s: mismatch sector in range "
4576 						    "%llu-%llu\n", mdname(conf->mddev),
4577 						    (unsigned long long) sh->sector,
4578 						    (unsigned long long) sh->sector +
4579 						    RAID5_STRIPE_SECTORS(conf));
4580 			} else {
4581 				int *target = &sh->ops.target;
4582 
4583 				sh->ops.target = -1;
4584 				sh->ops.target2 = -1;
4585 				sh->check_state = check_state_compute_run;
4586 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4587 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4588 				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4589 					set_bit(R5_Wantcompute,
4590 						&sh->dev[pd_idx].flags);
4591 					*target = pd_idx;
4592 					target = &sh->ops.target2;
4593 					s->uptodate++;
4594 				}
4595 				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4596 					set_bit(R5_Wantcompute,
4597 						&sh->dev[qd_idx].flags);
4598 					*target = qd_idx;
4599 					s->uptodate++;
4600 				}
4601 			}
4602 		}
4603 		break;
4604 	case check_state_compute_run:
4605 		break;
4606 	default:
4607 		pr_warn("%s: unknown check_state: %d sector: %llu\n",
4608 			__func__, sh->check_state,
4609 			(unsigned long long) sh->sector);
4610 		BUG();
4611 	}
4612 }
4613 
4614 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
4615 {
4616 	int i;
4617 
4618 	/* We have read all the blocks in this stripe and now we need to
4619 	 * copy some of them into a target stripe for expand.
4620 	 */
4621 	struct dma_async_tx_descriptor *tx = NULL;
4622 	BUG_ON(sh->batch_head);
4623 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4624 	for (i = 0; i < sh->disks; i++)
4625 		if (i != sh->pd_idx && i != sh->qd_idx) {
4626 			int dd_idx, j;
4627 			struct stripe_head *sh2;
4628 			struct async_submit_ctl submit;
4629 
4630 			sector_t bn = raid5_compute_blocknr(sh, i, 1);
4631 			sector_t s = raid5_compute_sector(conf, bn, 0,
4632 							  &dd_idx, NULL);
4633 			sh2 = raid5_get_active_stripe(conf, NULL, s,
4634 				R5_GAS_NOBLOCK | R5_GAS_NOQUIESCE);
4635 			if (sh2 == NULL)
4636 				/* so far only the early blocks of this stripe
4637 				 * have been requested.  When later blocks
4638 				 * get requested, we will try again
4639 				 */
4640 				continue;
4641 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
4642 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
4643 				/* must have already done this block */
4644 				raid5_release_stripe(sh2);
4645 				continue;
4646 			}
4647 
4648 			/* place all the copies on one channel */
4649 			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4650 			tx = async_memcpy(sh2->dev[dd_idx].page,
4651 					  sh->dev[i].page, sh2->dev[dd_idx].offset,
4652 					  sh->dev[i].offset, RAID5_STRIPE_SIZE(conf),
4653 					  &submit);
4654 
4655 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4656 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4657 			for (j = 0; j < conf->raid_disks; j++)
4658 				if (j != sh2->pd_idx &&
4659 				    j != sh2->qd_idx &&
4660 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
4661 					break;
4662 			if (j == conf->raid_disks) {
4663 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
4664 				set_bit(STRIPE_HANDLE, &sh2->state);
4665 			}
4666 			raid5_release_stripe(sh2);
4667 
4668 		}
4669 	/* done submitting copies, wait for them to complete */
4670 	async_tx_quiesce(&tx);
4671 }
4672 
4673 /*
4674  * handle_stripe - do things to a stripe.
4675  *
4676  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4677  * state of various bits to see what needs to be done.
4678  * Possible results:
4679  *    return some read requests which now have data
4680  *    return some write requests which are safely on storage
4681  *    schedule a read on some buffers
4682  *    schedule a write of some buffers
4683  *    return confirmation of parity correctness
4684  *
4685  */
4686 
4687 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4688 {
4689 	struct r5conf *conf = sh->raid_conf;
4690 	int disks = sh->disks;
4691 	struct r5dev *dev;
4692 	int i;
4693 	int do_recovery = 0;
4694 
4695 	memset(s, 0, sizeof(*s));
4696 
4697 	s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4698 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4699 	s->failed_num[0] = -1;
4700 	s->failed_num[1] = -1;
4701 	s->log_failed = r5l_log_disk_error(conf);
4702 
4703 	/* Now to look around and see what can be done */
4704 	rcu_read_lock();
4705 	for (i=disks; i--; ) {
4706 		struct md_rdev *rdev;
4707 		sector_t first_bad;
4708 		int bad_sectors;
4709 		int is_bad = 0;
4710 
4711 		dev = &sh->dev[i];
4712 
4713 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4714 			 i, dev->flags,
4715 			 dev->toread, dev->towrite, dev->written);
4716 		/* maybe we can reply to a read
4717 		 *
4718 		 * new wantfill requests are only permitted while
4719 		 * ops_complete_biofill is guaranteed to be inactive
4720 		 */
4721 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4722 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4723 			set_bit(R5_Wantfill, &dev->flags);
4724 
4725 		/* now count some things */
4726 		if (test_bit(R5_LOCKED, &dev->flags))
4727 			s->locked++;
4728 		if (test_bit(R5_UPTODATE, &dev->flags))
4729 			s->uptodate++;
4730 		if (test_bit(R5_Wantcompute, &dev->flags)) {
4731 			s->compute++;
4732 			BUG_ON(s->compute > 2);
4733 		}
4734 
4735 		if (test_bit(R5_Wantfill, &dev->flags))
4736 			s->to_fill++;
4737 		else if (dev->toread)
4738 			s->to_read++;
4739 		if (dev->towrite) {
4740 			s->to_write++;
4741 			if (!test_bit(R5_OVERWRITE, &dev->flags))
4742 				s->non_overwrite++;
4743 		}
4744 		if (dev->written)
4745 			s->written++;
4746 		/* Prefer to use the replacement for reads, but only
4747 		 * if it is recovered enough and has no bad blocks.
4748 		 */
4749 		rdev = rcu_dereference(conf->disks[i].replacement);
4750 		if (rdev && !test_bit(Faulty, &rdev->flags) &&
4751 		    rdev->recovery_offset >= sh->sector + RAID5_STRIPE_SECTORS(conf) &&
4752 		    !is_badblock(rdev, sh->sector, RAID5_STRIPE_SECTORS(conf),
4753 				 &first_bad, &bad_sectors))
4754 			set_bit(R5_ReadRepl, &dev->flags);
4755 		else {
4756 			if (rdev && !test_bit(Faulty, &rdev->flags))
4757 				set_bit(R5_NeedReplace, &dev->flags);
4758 			else
4759 				clear_bit(R5_NeedReplace, &dev->flags);
4760 			rdev = rcu_dereference(conf->disks[i].rdev);
4761 			clear_bit(R5_ReadRepl, &dev->flags);
4762 		}
4763 		if (rdev && test_bit(Faulty, &rdev->flags))
4764 			rdev = NULL;
4765 		if (rdev) {
4766 			is_bad = is_badblock(rdev, sh->sector, RAID5_STRIPE_SECTORS(conf),
4767 					     &first_bad, &bad_sectors);
4768 			if (s->blocked_rdev == NULL
4769 			    && (test_bit(Blocked, &rdev->flags)
4770 				|| is_bad < 0)) {
4771 				if (is_bad < 0)
4772 					set_bit(BlockedBadBlocks,
4773 						&rdev->flags);
4774 				s->blocked_rdev = rdev;
4775 				atomic_inc(&rdev->nr_pending);
4776 			}
4777 		}
4778 		clear_bit(R5_Insync, &dev->flags);
4779 		if (!rdev)
4780 			/* Not in-sync */;
4781 		else if (is_bad) {
4782 			/* also not in-sync */
4783 			if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4784 			    test_bit(R5_UPTODATE, &dev->flags)) {
4785 				/* treat as in-sync, but with a read error
4786 				 * which we can now try to correct
4787 				 */
4788 				set_bit(R5_Insync, &dev->flags);
4789 				set_bit(R5_ReadError, &dev->flags);
4790 			}
4791 		} else if (test_bit(In_sync, &rdev->flags))
4792 			set_bit(R5_Insync, &dev->flags);
4793 		else if (sh->sector + RAID5_STRIPE_SECTORS(conf) <= rdev->recovery_offset)
4794 			/* in sync if before recovery_offset */
4795 			set_bit(R5_Insync, &dev->flags);
4796 		else if (test_bit(R5_UPTODATE, &dev->flags) &&
4797 			 test_bit(R5_Expanded, &dev->flags))
4798 			/* If we've reshaped into here, we assume it is Insync.
4799 			 * We will shortly update recovery_offset to make
4800 			 * it official.
4801 			 */
4802 			set_bit(R5_Insync, &dev->flags);
4803 
4804 		if (test_bit(R5_WriteError, &dev->flags)) {
4805 			/* This flag does not apply to '.replacement'
4806 			 * only to .rdev, so make sure to check that*/
4807 			struct md_rdev *rdev2 = rcu_dereference(
4808 				conf->disks[i].rdev);
4809 			if (rdev2 == rdev)
4810 				clear_bit(R5_Insync, &dev->flags);
4811 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4812 				s->handle_bad_blocks = 1;
4813 				atomic_inc(&rdev2->nr_pending);
4814 			} else
4815 				clear_bit(R5_WriteError, &dev->flags);
4816 		}
4817 		if (test_bit(R5_MadeGood, &dev->flags)) {
4818 			/* This flag does not apply to '.replacement'
4819 			 * only to .rdev, so make sure to check that*/
4820 			struct md_rdev *rdev2 = rcu_dereference(
4821 				conf->disks[i].rdev);
4822 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4823 				s->handle_bad_blocks = 1;
4824 				atomic_inc(&rdev2->nr_pending);
4825 			} else
4826 				clear_bit(R5_MadeGood, &dev->flags);
4827 		}
4828 		if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4829 			struct md_rdev *rdev2 = rcu_dereference(
4830 				conf->disks[i].replacement);
4831 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4832 				s->handle_bad_blocks = 1;
4833 				atomic_inc(&rdev2->nr_pending);
4834 			} else
4835 				clear_bit(R5_MadeGoodRepl, &dev->flags);
4836 		}
4837 		if (!test_bit(R5_Insync, &dev->flags)) {
4838 			/* The ReadError flag will just be confusing now */
4839 			clear_bit(R5_ReadError, &dev->flags);
4840 			clear_bit(R5_ReWrite, &dev->flags);
4841 		}
4842 		if (test_bit(R5_ReadError, &dev->flags))
4843 			clear_bit(R5_Insync, &dev->flags);
4844 		if (!test_bit(R5_Insync, &dev->flags)) {
4845 			if (s->failed < 2)
4846 				s->failed_num[s->failed] = i;
4847 			s->failed++;
4848 			if (rdev && !test_bit(Faulty, &rdev->flags))
4849 				do_recovery = 1;
4850 			else if (!rdev) {
4851 				rdev = rcu_dereference(
4852 				    conf->disks[i].replacement);
4853 				if (rdev && !test_bit(Faulty, &rdev->flags))
4854 					do_recovery = 1;
4855 			}
4856 		}
4857 
4858 		if (test_bit(R5_InJournal, &dev->flags))
4859 			s->injournal++;
4860 		if (test_bit(R5_InJournal, &dev->flags) && dev->written)
4861 			s->just_cached++;
4862 	}
4863 	if (test_bit(STRIPE_SYNCING, &sh->state)) {
4864 		/* If there is a failed device being replaced,
4865 		 *     we must be recovering.
4866 		 * else if we are after recovery_cp, we must be syncing
4867 		 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4868 		 * else we can only be replacing
4869 		 * sync and recovery both need to read all devices, and so
4870 		 * use the same flag.
4871 		 */
4872 		if (do_recovery ||
4873 		    sh->sector >= conf->mddev->recovery_cp ||
4874 		    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4875 			s->syncing = 1;
4876 		else
4877 			s->replacing = 1;
4878 	}
4879 	rcu_read_unlock();
4880 }
4881 
4882 /*
4883  * Return '1' if this is a member of batch, or '0' if it is a lone stripe or
4884  * a head which can now be handled.
4885  */
4886 static int clear_batch_ready(struct stripe_head *sh)
4887 {
4888 	struct stripe_head *tmp;
4889 	if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4890 		return (sh->batch_head && sh->batch_head != sh);
4891 	spin_lock(&sh->stripe_lock);
4892 	if (!sh->batch_head) {
4893 		spin_unlock(&sh->stripe_lock);
4894 		return 0;
4895 	}
4896 
4897 	/*
4898 	 * this stripe could be added to a batch list before we check
4899 	 * BATCH_READY, skips it
4900 	 */
4901 	if (sh->batch_head != sh) {
4902 		spin_unlock(&sh->stripe_lock);
4903 		return 1;
4904 	}
4905 	spin_lock(&sh->batch_lock);
4906 	list_for_each_entry(tmp, &sh->batch_list, batch_list)
4907 		clear_bit(STRIPE_BATCH_READY, &tmp->state);
4908 	spin_unlock(&sh->batch_lock);
4909 	spin_unlock(&sh->stripe_lock);
4910 
4911 	/*
4912 	 * BATCH_READY is cleared, no new stripes can be added.
4913 	 * batch_list can be accessed without lock
4914 	 */
4915 	return 0;
4916 }
4917 
4918 static void break_stripe_batch_list(struct stripe_head *head_sh,
4919 				    unsigned long handle_flags)
4920 {
4921 	struct stripe_head *sh, *next;
4922 	int i;
4923 	int do_wakeup = 0;
4924 
4925 	list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4926 
4927 		list_del_init(&sh->batch_list);
4928 
4929 		WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4930 					  (1 << STRIPE_SYNCING) |
4931 					  (1 << STRIPE_REPLACED) |
4932 					  (1 << STRIPE_DELAYED) |
4933 					  (1 << STRIPE_BIT_DELAY) |
4934 					  (1 << STRIPE_FULL_WRITE) |
4935 					  (1 << STRIPE_BIOFILL_RUN) |
4936 					  (1 << STRIPE_COMPUTE_RUN)  |
4937 					  (1 << STRIPE_DISCARD) |
4938 					  (1 << STRIPE_BATCH_READY) |
4939 					  (1 << STRIPE_BATCH_ERR) |
4940 					  (1 << STRIPE_BITMAP_PENDING)),
4941 			"stripe state: %lx\n", sh->state);
4942 		WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4943 					      (1 << STRIPE_REPLACED)),
4944 			"head stripe state: %lx\n", head_sh->state);
4945 
4946 		set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4947 					    (1 << STRIPE_PREREAD_ACTIVE) |
4948 					    (1 << STRIPE_DEGRADED) |
4949 					    (1 << STRIPE_ON_UNPLUG_LIST)),
4950 			      head_sh->state & (1 << STRIPE_INSYNC));
4951 
4952 		sh->check_state = head_sh->check_state;
4953 		sh->reconstruct_state = head_sh->reconstruct_state;
4954 		spin_lock_irq(&sh->stripe_lock);
4955 		sh->batch_head = NULL;
4956 		spin_unlock_irq(&sh->stripe_lock);
4957 		for (i = 0; i < sh->disks; i++) {
4958 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4959 				do_wakeup = 1;
4960 			sh->dev[i].flags = head_sh->dev[i].flags &
4961 				(~((1 << R5_WriteError) | (1 << R5_Overlap)));
4962 		}
4963 		if (handle_flags == 0 ||
4964 		    sh->state & handle_flags)
4965 			set_bit(STRIPE_HANDLE, &sh->state);
4966 		raid5_release_stripe(sh);
4967 	}
4968 	spin_lock_irq(&head_sh->stripe_lock);
4969 	head_sh->batch_head = NULL;
4970 	spin_unlock_irq(&head_sh->stripe_lock);
4971 	for (i = 0; i < head_sh->disks; i++)
4972 		if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4973 			do_wakeup = 1;
4974 	if (head_sh->state & handle_flags)
4975 		set_bit(STRIPE_HANDLE, &head_sh->state);
4976 
4977 	if (do_wakeup)
4978 		wake_up(&head_sh->raid_conf->wait_for_overlap);
4979 }
4980 
4981 static void handle_stripe(struct stripe_head *sh)
4982 {
4983 	struct stripe_head_state s;
4984 	struct r5conf *conf = sh->raid_conf;
4985 	int i;
4986 	int prexor;
4987 	int disks = sh->disks;
4988 	struct r5dev *pdev, *qdev;
4989 
4990 	clear_bit(STRIPE_HANDLE, &sh->state);
4991 
4992 	/*
4993 	 * handle_stripe should not continue handle the batched stripe, only
4994 	 * the head of batch list or lone stripe can continue. Otherwise we
4995 	 * could see break_stripe_batch_list warns about the STRIPE_ACTIVE
4996 	 * is set for the batched stripe.
4997 	 */
4998 	if (clear_batch_ready(sh))
4999 		return;
5000 
5001 	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
5002 		/* already being handled, ensure it gets handled
5003 		 * again when current action finishes */
5004 		set_bit(STRIPE_HANDLE, &sh->state);
5005 		return;
5006 	}
5007 
5008 	if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
5009 		break_stripe_batch_list(sh, 0);
5010 
5011 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
5012 		spin_lock(&sh->stripe_lock);
5013 		/*
5014 		 * Cannot process 'sync' concurrently with 'discard'.
5015 		 * Flush data in r5cache before 'sync'.
5016 		 */
5017 		if (!test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) &&
5018 		    !test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state) &&
5019 		    !test_bit(STRIPE_DISCARD, &sh->state) &&
5020 		    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
5021 			set_bit(STRIPE_SYNCING, &sh->state);
5022 			clear_bit(STRIPE_INSYNC, &sh->state);
5023 			clear_bit(STRIPE_REPLACED, &sh->state);
5024 		}
5025 		spin_unlock(&sh->stripe_lock);
5026 	}
5027 	clear_bit(STRIPE_DELAYED, &sh->state);
5028 
5029 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
5030 		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
5031 	       (unsigned long long)sh->sector, sh->state,
5032 	       atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
5033 	       sh->check_state, sh->reconstruct_state);
5034 
5035 	analyse_stripe(sh, &s);
5036 
5037 	if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
5038 		goto finish;
5039 
5040 	if (s.handle_bad_blocks ||
5041 	    test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) {
5042 		set_bit(STRIPE_HANDLE, &sh->state);
5043 		goto finish;
5044 	}
5045 
5046 	if (unlikely(s.blocked_rdev)) {
5047 		if (s.syncing || s.expanding || s.expanded ||
5048 		    s.replacing || s.to_write || s.written) {
5049 			set_bit(STRIPE_HANDLE, &sh->state);
5050 			goto finish;
5051 		}
5052 		/* There is nothing for the blocked_rdev to block */
5053 		rdev_dec_pending(s.blocked_rdev, conf->mddev);
5054 		s.blocked_rdev = NULL;
5055 	}
5056 
5057 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
5058 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
5059 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
5060 	}
5061 
5062 	pr_debug("locked=%d uptodate=%d to_read=%d"
5063 	       " to_write=%d failed=%d failed_num=%d,%d\n",
5064 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
5065 	       s.failed_num[0], s.failed_num[1]);
5066 	/*
5067 	 * check if the array has lost more than max_degraded devices and,
5068 	 * if so, some requests might need to be failed.
5069 	 *
5070 	 * When journal device failed (log_failed), we will only process
5071 	 * the stripe if there is data need write to raid disks
5072 	 */
5073 	if (s.failed > conf->max_degraded ||
5074 	    (s.log_failed && s.injournal == 0)) {
5075 		sh->check_state = 0;
5076 		sh->reconstruct_state = 0;
5077 		break_stripe_batch_list(sh, 0);
5078 		if (s.to_read+s.to_write+s.written)
5079 			handle_failed_stripe(conf, sh, &s, disks);
5080 		if (s.syncing + s.replacing)
5081 			handle_failed_sync(conf, sh, &s);
5082 	}
5083 
5084 	/* Now we check to see if any write operations have recently
5085 	 * completed
5086 	 */
5087 	prexor = 0;
5088 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
5089 		prexor = 1;
5090 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
5091 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
5092 		sh->reconstruct_state = reconstruct_state_idle;
5093 
5094 		/* All the 'written' buffers and the parity block are ready to
5095 		 * be written back to disk
5096 		 */
5097 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
5098 		       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
5099 		BUG_ON(sh->qd_idx >= 0 &&
5100 		       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
5101 		       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
5102 		for (i = disks; i--; ) {
5103 			struct r5dev *dev = &sh->dev[i];
5104 			if (test_bit(R5_LOCKED, &dev->flags) &&
5105 				(i == sh->pd_idx || i == sh->qd_idx ||
5106 				 dev->written || test_bit(R5_InJournal,
5107 							  &dev->flags))) {
5108 				pr_debug("Writing block %d\n", i);
5109 				set_bit(R5_Wantwrite, &dev->flags);
5110 				if (prexor)
5111 					continue;
5112 				if (s.failed > 1)
5113 					continue;
5114 				if (!test_bit(R5_Insync, &dev->flags) ||
5115 				    ((i == sh->pd_idx || i == sh->qd_idx)  &&
5116 				     s.failed == 0))
5117 					set_bit(STRIPE_INSYNC, &sh->state);
5118 			}
5119 		}
5120 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5121 			s.dec_preread_active = 1;
5122 	}
5123 
5124 	/*
5125 	 * might be able to return some write requests if the parity blocks
5126 	 * are safe, or on a failed drive
5127 	 */
5128 	pdev = &sh->dev[sh->pd_idx];
5129 	s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
5130 		|| (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
5131 	qdev = &sh->dev[sh->qd_idx];
5132 	s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
5133 		|| (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
5134 		|| conf->level < 6;
5135 
5136 	if (s.written &&
5137 	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
5138 			     && !test_bit(R5_LOCKED, &pdev->flags)
5139 			     && (test_bit(R5_UPTODATE, &pdev->flags) ||
5140 				 test_bit(R5_Discard, &pdev->flags))))) &&
5141 	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
5142 			     && !test_bit(R5_LOCKED, &qdev->flags)
5143 			     && (test_bit(R5_UPTODATE, &qdev->flags) ||
5144 				 test_bit(R5_Discard, &qdev->flags))))))
5145 		handle_stripe_clean_event(conf, sh, disks);
5146 
5147 	if (s.just_cached)
5148 		r5c_handle_cached_data_endio(conf, sh, disks);
5149 	log_stripe_write_finished(sh);
5150 
5151 	/* Now we might consider reading some blocks, either to check/generate
5152 	 * parity, or to satisfy requests
5153 	 * or to load a block that is being partially written.
5154 	 */
5155 	if (s.to_read || s.non_overwrite
5156 	    || (s.to_write && s.failed)
5157 	    || (s.syncing && (s.uptodate + s.compute < disks))
5158 	    || s.replacing
5159 	    || s.expanding)
5160 		handle_stripe_fill(sh, &s, disks);
5161 
5162 	/*
5163 	 * When the stripe finishes full journal write cycle (write to journal
5164 	 * and raid disk), this is the clean up procedure so it is ready for
5165 	 * next operation.
5166 	 */
5167 	r5c_finish_stripe_write_out(conf, sh, &s);
5168 
5169 	/*
5170 	 * Now to consider new write requests, cache write back and what else,
5171 	 * if anything should be read.  We do not handle new writes when:
5172 	 * 1/ A 'write' operation (copy+xor) is already in flight.
5173 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
5174 	 *    block.
5175 	 * 3/ A r5c cache log write is in flight.
5176 	 */
5177 
5178 	if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
5179 		if (!r5c_is_writeback(conf->log)) {
5180 			if (s.to_write)
5181 				handle_stripe_dirtying(conf, sh, &s, disks);
5182 		} else { /* write back cache */
5183 			int ret = 0;
5184 
5185 			/* First, try handle writes in caching phase */
5186 			if (s.to_write)
5187 				ret = r5c_try_caching_write(conf, sh, &s,
5188 							    disks);
5189 			/*
5190 			 * If caching phase failed: ret == -EAGAIN
5191 			 *    OR
5192 			 * stripe under reclaim: !caching && injournal
5193 			 *
5194 			 * fall back to handle_stripe_dirtying()
5195 			 */
5196 			if (ret == -EAGAIN ||
5197 			    /* stripe under reclaim: !caching && injournal */
5198 			    (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
5199 			     s.injournal > 0)) {
5200 				ret = handle_stripe_dirtying(conf, sh, &s,
5201 							     disks);
5202 				if (ret == -EAGAIN)
5203 					goto finish;
5204 			}
5205 		}
5206 	}
5207 
5208 	/* maybe we need to check and possibly fix the parity for this stripe
5209 	 * Any reads will already have been scheduled, so we just see if enough
5210 	 * data is available.  The parity check is held off while parity
5211 	 * dependent operations are in flight.
5212 	 */
5213 	if (sh->check_state ||
5214 	    (s.syncing && s.locked == 0 &&
5215 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
5216 	     !test_bit(STRIPE_INSYNC, &sh->state))) {
5217 		if (conf->level == 6)
5218 			handle_parity_checks6(conf, sh, &s, disks);
5219 		else
5220 			handle_parity_checks5(conf, sh, &s, disks);
5221 	}
5222 
5223 	if ((s.replacing || s.syncing) && s.locked == 0
5224 	    && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
5225 	    && !test_bit(STRIPE_REPLACED, &sh->state)) {
5226 		/* Write out to replacement devices where possible */
5227 		for (i = 0; i < conf->raid_disks; i++)
5228 			if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
5229 				WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
5230 				set_bit(R5_WantReplace, &sh->dev[i].flags);
5231 				set_bit(R5_LOCKED, &sh->dev[i].flags);
5232 				s.locked++;
5233 			}
5234 		if (s.replacing)
5235 			set_bit(STRIPE_INSYNC, &sh->state);
5236 		set_bit(STRIPE_REPLACED, &sh->state);
5237 	}
5238 	if ((s.syncing || s.replacing) && s.locked == 0 &&
5239 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
5240 	    test_bit(STRIPE_INSYNC, &sh->state)) {
5241 		md_done_sync(conf->mddev, RAID5_STRIPE_SECTORS(conf), 1);
5242 		clear_bit(STRIPE_SYNCING, &sh->state);
5243 		if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
5244 			wake_up(&conf->wait_for_overlap);
5245 	}
5246 
5247 	/* If the failed drives are just a ReadError, then we might need
5248 	 * to progress the repair/check process
5249 	 */
5250 	if (s.failed <= conf->max_degraded && !conf->mddev->ro)
5251 		for (i = 0; i < s.failed; i++) {
5252 			struct r5dev *dev = &sh->dev[s.failed_num[i]];
5253 			if (test_bit(R5_ReadError, &dev->flags)
5254 			    && !test_bit(R5_LOCKED, &dev->flags)
5255 			    && test_bit(R5_UPTODATE, &dev->flags)
5256 				) {
5257 				if (!test_bit(R5_ReWrite, &dev->flags)) {
5258 					set_bit(R5_Wantwrite, &dev->flags);
5259 					set_bit(R5_ReWrite, &dev->flags);
5260 				} else
5261 					/* let's read it back */
5262 					set_bit(R5_Wantread, &dev->flags);
5263 				set_bit(R5_LOCKED, &dev->flags);
5264 				s.locked++;
5265 			}
5266 		}
5267 
5268 	/* Finish reconstruct operations initiated by the expansion process */
5269 	if (sh->reconstruct_state == reconstruct_state_result) {
5270 		struct stripe_head *sh_src
5271 			= raid5_get_active_stripe(conf, NULL, sh->sector,
5272 					R5_GAS_PREVIOUS | R5_GAS_NOBLOCK |
5273 					R5_GAS_NOQUIESCE);
5274 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
5275 			/* sh cannot be written until sh_src has been read.
5276 			 * so arrange for sh to be delayed a little
5277 			 */
5278 			set_bit(STRIPE_DELAYED, &sh->state);
5279 			set_bit(STRIPE_HANDLE, &sh->state);
5280 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
5281 					      &sh_src->state))
5282 				atomic_inc(&conf->preread_active_stripes);
5283 			raid5_release_stripe(sh_src);
5284 			goto finish;
5285 		}
5286 		if (sh_src)
5287 			raid5_release_stripe(sh_src);
5288 
5289 		sh->reconstruct_state = reconstruct_state_idle;
5290 		clear_bit(STRIPE_EXPANDING, &sh->state);
5291 		for (i = conf->raid_disks; i--; ) {
5292 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
5293 			set_bit(R5_LOCKED, &sh->dev[i].flags);
5294 			s.locked++;
5295 		}
5296 	}
5297 
5298 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
5299 	    !sh->reconstruct_state) {
5300 		/* Need to write out all blocks after computing parity */
5301 		sh->disks = conf->raid_disks;
5302 		stripe_set_idx(sh->sector, conf, 0, sh);
5303 		schedule_reconstruction(sh, &s, 1, 1);
5304 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
5305 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
5306 		atomic_dec(&conf->reshape_stripes);
5307 		wake_up(&conf->wait_for_overlap);
5308 		md_done_sync(conf->mddev, RAID5_STRIPE_SECTORS(conf), 1);
5309 	}
5310 
5311 	if (s.expanding && s.locked == 0 &&
5312 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
5313 		handle_stripe_expansion(conf, sh);
5314 
5315 finish:
5316 	/* wait for this device to become unblocked */
5317 	if (unlikely(s.blocked_rdev)) {
5318 		if (conf->mddev->external)
5319 			md_wait_for_blocked_rdev(s.blocked_rdev,
5320 						 conf->mddev);
5321 		else
5322 			/* Internal metadata will immediately
5323 			 * be written by raid5d, so we don't
5324 			 * need to wait here.
5325 			 */
5326 			rdev_dec_pending(s.blocked_rdev,
5327 					 conf->mddev);
5328 	}
5329 
5330 	if (s.handle_bad_blocks)
5331 		for (i = disks; i--; ) {
5332 			struct md_rdev *rdev;
5333 			struct r5dev *dev = &sh->dev[i];
5334 			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
5335 				/* We own a safe reference to the rdev */
5336 				rdev = rdev_pend_deref(conf->disks[i].rdev);
5337 				if (!rdev_set_badblocks(rdev, sh->sector,
5338 							RAID5_STRIPE_SECTORS(conf), 0))
5339 					md_error(conf->mddev, rdev);
5340 				rdev_dec_pending(rdev, conf->mddev);
5341 			}
5342 			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
5343 				rdev = rdev_pend_deref(conf->disks[i].rdev);
5344 				rdev_clear_badblocks(rdev, sh->sector,
5345 						     RAID5_STRIPE_SECTORS(conf), 0);
5346 				rdev_dec_pending(rdev, conf->mddev);
5347 			}
5348 			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
5349 				rdev = rdev_pend_deref(conf->disks[i].replacement);
5350 				if (!rdev)
5351 					/* rdev have been moved down */
5352 					rdev = rdev_pend_deref(conf->disks[i].rdev);
5353 				rdev_clear_badblocks(rdev, sh->sector,
5354 						     RAID5_STRIPE_SECTORS(conf), 0);
5355 				rdev_dec_pending(rdev, conf->mddev);
5356 			}
5357 		}
5358 
5359 	if (s.ops_request)
5360 		raid_run_ops(sh, s.ops_request);
5361 
5362 	ops_run_io(sh, &s);
5363 
5364 	if (s.dec_preread_active) {
5365 		/* We delay this until after ops_run_io so that if make_request
5366 		 * is waiting on a flush, it won't continue until the writes
5367 		 * have actually been submitted.
5368 		 */
5369 		atomic_dec(&conf->preread_active_stripes);
5370 		if (atomic_read(&conf->preread_active_stripes) <
5371 		    IO_THRESHOLD)
5372 			md_wakeup_thread(conf->mddev->thread);
5373 	}
5374 
5375 	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
5376 }
5377 
5378 static void raid5_activate_delayed(struct r5conf *conf)
5379 	__must_hold(&conf->device_lock)
5380 {
5381 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
5382 		while (!list_empty(&conf->delayed_list)) {
5383 			struct list_head *l = conf->delayed_list.next;
5384 			struct stripe_head *sh;
5385 			sh = list_entry(l, struct stripe_head, lru);
5386 			list_del_init(l);
5387 			clear_bit(STRIPE_DELAYED, &sh->state);
5388 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5389 				atomic_inc(&conf->preread_active_stripes);
5390 			list_add_tail(&sh->lru, &conf->hold_list);
5391 			raid5_wakeup_stripe_thread(sh);
5392 		}
5393 	}
5394 }
5395 
5396 static void activate_bit_delay(struct r5conf *conf,
5397 		struct list_head *temp_inactive_list)
5398 	__must_hold(&conf->device_lock)
5399 {
5400 	struct list_head head;
5401 	list_add(&head, &conf->bitmap_list);
5402 	list_del_init(&conf->bitmap_list);
5403 	while (!list_empty(&head)) {
5404 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
5405 		int hash;
5406 		list_del_init(&sh->lru);
5407 		atomic_inc(&sh->count);
5408 		hash = sh->hash_lock_index;
5409 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
5410 	}
5411 }
5412 
5413 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
5414 {
5415 	struct r5conf *conf = mddev->private;
5416 	sector_t sector = bio->bi_iter.bi_sector;
5417 	unsigned int chunk_sectors;
5418 	unsigned int bio_sectors = bio_sectors(bio);
5419 
5420 	chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
5421 	return  chunk_sectors >=
5422 		((sector & (chunk_sectors - 1)) + bio_sectors);
5423 }
5424 
5425 /*
5426  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
5427  *  later sampled by raid5d.
5428  */
5429 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
5430 {
5431 	unsigned long flags;
5432 
5433 	spin_lock_irqsave(&conf->device_lock, flags);
5434 
5435 	bi->bi_next = conf->retry_read_aligned_list;
5436 	conf->retry_read_aligned_list = bi;
5437 
5438 	spin_unlock_irqrestore(&conf->device_lock, flags);
5439 	md_wakeup_thread(conf->mddev->thread);
5440 }
5441 
5442 static struct bio *remove_bio_from_retry(struct r5conf *conf,
5443 					 unsigned int *offset)
5444 {
5445 	struct bio *bi;
5446 
5447 	bi = conf->retry_read_aligned;
5448 	if (bi) {
5449 		*offset = conf->retry_read_offset;
5450 		conf->retry_read_aligned = NULL;
5451 		return bi;
5452 	}
5453 	bi = conf->retry_read_aligned_list;
5454 	if(bi) {
5455 		conf->retry_read_aligned_list = bi->bi_next;
5456 		bi->bi_next = NULL;
5457 		*offset = 0;
5458 	}
5459 
5460 	return bi;
5461 }
5462 
5463 /*
5464  *  The "raid5_align_endio" should check if the read succeeded and if it
5465  *  did, call bio_endio on the original bio (having bio_put the new bio
5466  *  first).
5467  *  If the read failed..
5468  */
5469 static void raid5_align_endio(struct bio *bi)
5470 {
5471 	struct md_io_acct *md_io_acct = bi->bi_private;
5472 	struct bio *raid_bi = md_io_acct->orig_bio;
5473 	struct mddev *mddev;
5474 	struct r5conf *conf;
5475 	struct md_rdev *rdev;
5476 	blk_status_t error = bi->bi_status;
5477 	unsigned long start_time = md_io_acct->start_time;
5478 
5479 	bio_put(bi);
5480 
5481 	rdev = (void*)raid_bi->bi_next;
5482 	raid_bi->bi_next = NULL;
5483 	mddev = rdev->mddev;
5484 	conf = mddev->private;
5485 
5486 	rdev_dec_pending(rdev, conf->mddev);
5487 
5488 	if (!error) {
5489 		if (blk_queue_io_stat(raid_bi->bi_bdev->bd_disk->queue))
5490 			bio_end_io_acct(raid_bi, start_time);
5491 		bio_endio(raid_bi);
5492 		if (atomic_dec_and_test(&conf->active_aligned_reads))
5493 			wake_up(&conf->wait_for_quiescent);
5494 		return;
5495 	}
5496 
5497 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
5498 
5499 	add_bio_to_retry(raid_bi, conf);
5500 }
5501 
5502 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
5503 {
5504 	struct r5conf *conf = mddev->private;
5505 	struct bio *align_bio;
5506 	struct md_rdev *rdev;
5507 	sector_t sector, end_sector, first_bad;
5508 	int bad_sectors, dd_idx;
5509 	struct md_io_acct *md_io_acct;
5510 	bool did_inc;
5511 
5512 	if (!in_chunk_boundary(mddev, raid_bio)) {
5513 		pr_debug("%s: non aligned\n", __func__);
5514 		return 0;
5515 	}
5516 
5517 	sector = raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector, 0,
5518 				      &dd_idx, NULL);
5519 	end_sector = sector + bio_sectors(raid_bio);
5520 
5521 	rcu_read_lock();
5522 	if (r5c_big_stripe_cached(conf, sector))
5523 		goto out_rcu_unlock;
5524 
5525 	rdev = rcu_dereference(conf->disks[dd_idx].replacement);
5526 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
5527 	    rdev->recovery_offset < end_sector) {
5528 		rdev = rcu_dereference(conf->disks[dd_idx].rdev);
5529 		if (!rdev)
5530 			goto out_rcu_unlock;
5531 		if (test_bit(Faulty, &rdev->flags) ||
5532 		    !(test_bit(In_sync, &rdev->flags) ||
5533 		      rdev->recovery_offset >= end_sector))
5534 			goto out_rcu_unlock;
5535 	}
5536 
5537 	atomic_inc(&rdev->nr_pending);
5538 	rcu_read_unlock();
5539 
5540 	if (is_badblock(rdev, sector, bio_sectors(raid_bio), &first_bad,
5541 			&bad_sectors)) {
5542 		rdev_dec_pending(rdev, mddev);
5543 		return 0;
5544 	}
5545 
5546 	align_bio = bio_alloc_clone(rdev->bdev, raid_bio, GFP_NOIO,
5547 				    &mddev->io_acct_set);
5548 	md_io_acct = container_of(align_bio, struct md_io_acct, bio_clone);
5549 	raid_bio->bi_next = (void *)rdev;
5550 	if (blk_queue_io_stat(raid_bio->bi_bdev->bd_disk->queue))
5551 		md_io_acct->start_time = bio_start_io_acct(raid_bio);
5552 	md_io_acct->orig_bio = raid_bio;
5553 
5554 	align_bio->bi_end_io = raid5_align_endio;
5555 	align_bio->bi_private = md_io_acct;
5556 	align_bio->bi_iter.bi_sector = sector;
5557 
5558 	/* No reshape active, so we can trust rdev->data_offset */
5559 	align_bio->bi_iter.bi_sector += rdev->data_offset;
5560 
5561 	did_inc = false;
5562 	if (conf->quiesce == 0) {
5563 		atomic_inc(&conf->active_aligned_reads);
5564 		did_inc = true;
5565 	}
5566 	/* need a memory barrier to detect the race with raid5_quiesce() */
5567 	if (!did_inc || smp_load_acquire(&conf->quiesce) != 0) {
5568 		/* quiesce is in progress, so we need to undo io activation and wait
5569 		 * for it to finish
5570 		 */
5571 		if (did_inc && atomic_dec_and_test(&conf->active_aligned_reads))
5572 			wake_up(&conf->wait_for_quiescent);
5573 		spin_lock_irq(&conf->device_lock);
5574 		wait_event_lock_irq(conf->wait_for_quiescent, conf->quiesce == 0,
5575 				    conf->device_lock);
5576 		atomic_inc(&conf->active_aligned_reads);
5577 		spin_unlock_irq(&conf->device_lock);
5578 	}
5579 
5580 	if (mddev->gendisk)
5581 		trace_block_bio_remap(align_bio, disk_devt(mddev->gendisk),
5582 				      raid_bio->bi_iter.bi_sector);
5583 	submit_bio_noacct(align_bio);
5584 	return 1;
5585 
5586 out_rcu_unlock:
5587 	rcu_read_unlock();
5588 	return 0;
5589 }
5590 
5591 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
5592 {
5593 	struct bio *split;
5594 	sector_t sector = raid_bio->bi_iter.bi_sector;
5595 	unsigned chunk_sects = mddev->chunk_sectors;
5596 	unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
5597 
5598 	if (sectors < bio_sectors(raid_bio)) {
5599 		struct r5conf *conf = mddev->private;
5600 		split = bio_split(raid_bio, sectors, GFP_NOIO, &conf->bio_split);
5601 		bio_chain(split, raid_bio);
5602 		submit_bio_noacct(raid_bio);
5603 		raid_bio = split;
5604 	}
5605 
5606 	if (!raid5_read_one_chunk(mddev, raid_bio))
5607 		return raid_bio;
5608 
5609 	return NULL;
5610 }
5611 
5612 /* __get_priority_stripe - get the next stripe to process
5613  *
5614  * Full stripe writes are allowed to pass preread active stripes up until
5615  * the bypass_threshold is exceeded.  In general the bypass_count
5616  * increments when the handle_list is handled before the hold_list; however, it
5617  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
5618  * stripe with in flight i/o.  The bypass_count will be reset when the
5619  * head of the hold_list has changed, i.e. the head was promoted to the
5620  * handle_list.
5621  */
5622 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
5623 	__must_hold(&conf->device_lock)
5624 {
5625 	struct stripe_head *sh, *tmp;
5626 	struct list_head *handle_list = NULL;
5627 	struct r5worker_group *wg;
5628 	bool second_try = !r5c_is_writeback(conf->log) &&
5629 		!r5l_log_disk_error(conf);
5630 	bool try_loprio = test_bit(R5C_LOG_TIGHT, &conf->cache_state) ||
5631 		r5l_log_disk_error(conf);
5632 
5633 again:
5634 	wg = NULL;
5635 	sh = NULL;
5636 	if (conf->worker_cnt_per_group == 0) {
5637 		handle_list = try_loprio ? &conf->loprio_list :
5638 					&conf->handle_list;
5639 	} else if (group != ANY_GROUP) {
5640 		handle_list = try_loprio ? &conf->worker_groups[group].loprio_list :
5641 				&conf->worker_groups[group].handle_list;
5642 		wg = &conf->worker_groups[group];
5643 	} else {
5644 		int i;
5645 		for (i = 0; i < conf->group_cnt; i++) {
5646 			handle_list = try_loprio ? &conf->worker_groups[i].loprio_list :
5647 				&conf->worker_groups[i].handle_list;
5648 			wg = &conf->worker_groups[i];
5649 			if (!list_empty(handle_list))
5650 				break;
5651 		}
5652 	}
5653 
5654 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
5655 		  __func__,
5656 		  list_empty(handle_list) ? "empty" : "busy",
5657 		  list_empty(&conf->hold_list) ? "empty" : "busy",
5658 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
5659 
5660 	if (!list_empty(handle_list)) {
5661 		sh = list_entry(handle_list->next, typeof(*sh), lru);
5662 
5663 		if (list_empty(&conf->hold_list))
5664 			conf->bypass_count = 0;
5665 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
5666 			if (conf->hold_list.next == conf->last_hold)
5667 				conf->bypass_count++;
5668 			else {
5669 				conf->last_hold = conf->hold_list.next;
5670 				conf->bypass_count -= conf->bypass_threshold;
5671 				if (conf->bypass_count < 0)
5672 					conf->bypass_count = 0;
5673 			}
5674 		}
5675 	} else if (!list_empty(&conf->hold_list) &&
5676 		   ((conf->bypass_threshold &&
5677 		     conf->bypass_count > conf->bypass_threshold) ||
5678 		    atomic_read(&conf->pending_full_writes) == 0)) {
5679 
5680 		list_for_each_entry(tmp, &conf->hold_list,  lru) {
5681 			if (conf->worker_cnt_per_group == 0 ||
5682 			    group == ANY_GROUP ||
5683 			    !cpu_online(tmp->cpu) ||
5684 			    cpu_to_group(tmp->cpu) == group) {
5685 				sh = tmp;
5686 				break;
5687 			}
5688 		}
5689 
5690 		if (sh) {
5691 			conf->bypass_count -= conf->bypass_threshold;
5692 			if (conf->bypass_count < 0)
5693 				conf->bypass_count = 0;
5694 		}
5695 		wg = NULL;
5696 	}
5697 
5698 	if (!sh) {
5699 		if (second_try)
5700 			return NULL;
5701 		second_try = true;
5702 		try_loprio = !try_loprio;
5703 		goto again;
5704 	}
5705 
5706 	if (wg) {
5707 		wg->stripes_cnt--;
5708 		sh->group = NULL;
5709 	}
5710 	list_del_init(&sh->lru);
5711 	BUG_ON(atomic_inc_return(&sh->count) != 1);
5712 	return sh;
5713 }
5714 
5715 struct raid5_plug_cb {
5716 	struct blk_plug_cb	cb;
5717 	struct list_head	list;
5718 	struct list_head	temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5719 };
5720 
5721 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5722 {
5723 	struct raid5_plug_cb *cb = container_of(
5724 		blk_cb, struct raid5_plug_cb, cb);
5725 	struct stripe_head *sh;
5726 	struct mddev *mddev = cb->cb.data;
5727 	struct r5conf *conf = mddev->private;
5728 	int cnt = 0;
5729 	int hash;
5730 
5731 	if (cb->list.next && !list_empty(&cb->list)) {
5732 		spin_lock_irq(&conf->device_lock);
5733 		while (!list_empty(&cb->list)) {
5734 			sh = list_first_entry(&cb->list, struct stripe_head, lru);
5735 			list_del_init(&sh->lru);
5736 			/*
5737 			 * avoid race release_stripe_plug() sees
5738 			 * STRIPE_ON_UNPLUG_LIST clear but the stripe
5739 			 * is still in our list
5740 			 */
5741 			smp_mb__before_atomic();
5742 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5743 			/*
5744 			 * STRIPE_ON_RELEASE_LIST could be set here. In that
5745 			 * case, the count is always > 1 here
5746 			 */
5747 			hash = sh->hash_lock_index;
5748 			__release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5749 			cnt++;
5750 		}
5751 		spin_unlock_irq(&conf->device_lock);
5752 	}
5753 	release_inactive_stripe_list(conf, cb->temp_inactive_list,
5754 				     NR_STRIPE_HASH_LOCKS);
5755 	if (mddev->queue)
5756 		trace_block_unplug(mddev->queue, cnt, !from_schedule);
5757 	kfree(cb);
5758 }
5759 
5760 static void release_stripe_plug(struct mddev *mddev,
5761 				struct stripe_head *sh)
5762 {
5763 	struct blk_plug_cb *blk_cb = blk_check_plugged(
5764 		raid5_unplug, mddev,
5765 		sizeof(struct raid5_plug_cb));
5766 	struct raid5_plug_cb *cb;
5767 
5768 	if (!blk_cb) {
5769 		raid5_release_stripe(sh);
5770 		return;
5771 	}
5772 
5773 	cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5774 
5775 	if (cb->list.next == NULL) {
5776 		int i;
5777 		INIT_LIST_HEAD(&cb->list);
5778 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5779 			INIT_LIST_HEAD(cb->temp_inactive_list + i);
5780 	}
5781 
5782 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5783 		list_add_tail(&sh->lru, &cb->list);
5784 	else
5785 		raid5_release_stripe(sh);
5786 }
5787 
5788 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5789 {
5790 	struct r5conf *conf = mddev->private;
5791 	sector_t logical_sector, last_sector;
5792 	struct stripe_head *sh;
5793 	int stripe_sectors;
5794 
5795 	/* We need to handle this when io_uring supports discard/trim */
5796 	if (WARN_ON_ONCE(bi->bi_opf & REQ_NOWAIT))
5797 		return;
5798 
5799 	if (mddev->reshape_position != MaxSector)
5800 		/* Skip discard while reshape is happening */
5801 		return;
5802 
5803 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
5804 	last_sector = bio_end_sector(bi);
5805 
5806 	bi->bi_next = NULL;
5807 
5808 	stripe_sectors = conf->chunk_sectors *
5809 		(conf->raid_disks - conf->max_degraded);
5810 	logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5811 					       stripe_sectors);
5812 	sector_div(last_sector, stripe_sectors);
5813 
5814 	logical_sector *= conf->chunk_sectors;
5815 	last_sector *= conf->chunk_sectors;
5816 
5817 	for (; logical_sector < last_sector;
5818 	     logical_sector += RAID5_STRIPE_SECTORS(conf)) {
5819 		DEFINE_WAIT(w);
5820 		int d;
5821 	again:
5822 		sh = raid5_get_active_stripe(conf, NULL, logical_sector, 0);
5823 		prepare_to_wait(&conf->wait_for_overlap, &w,
5824 				TASK_UNINTERRUPTIBLE);
5825 		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5826 		if (test_bit(STRIPE_SYNCING, &sh->state)) {
5827 			raid5_release_stripe(sh);
5828 			schedule();
5829 			goto again;
5830 		}
5831 		clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5832 		spin_lock_irq(&sh->stripe_lock);
5833 		for (d = 0; d < conf->raid_disks; d++) {
5834 			if (d == sh->pd_idx || d == sh->qd_idx)
5835 				continue;
5836 			if (sh->dev[d].towrite || sh->dev[d].toread) {
5837 				set_bit(R5_Overlap, &sh->dev[d].flags);
5838 				spin_unlock_irq(&sh->stripe_lock);
5839 				raid5_release_stripe(sh);
5840 				schedule();
5841 				goto again;
5842 			}
5843 		}
5844 		set_bit(STRIPE_DISCARD, &sh->state);
5845 		finish_wait(&conf->wait_for_overlap, &w);
5846 		sh->overwrite_disks = 0;
5847 		for (d = 0; d < conf->raid_disks; d++) {
5848 			if (d == sh->pd_idx || d == sh->qd_idx)
5849 				continue;
5850 			sh->dev[d].towrite = bi;
5851 			set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5852 			bio_inc_remaining(bi);
5853 			md_write_inc(mddev, bi);
5854 			sh->overwrite_disks++;
5855 		}
5856 		spin_unlock_irq(&sh->stripe_lock);
5857 		if (conf->mddev->bitmap) {
5858 			for (d = 0;
5859 			     d < conf->raid_disks - conf->max_degraded;
5860 			     d++)
5861 				md_bitmap_startwrite(mddev->bitmap,
5862 						     sh->sector,
5863 						     RAID5_STRIPE_SECTORS(conf),
5864 						     0);
5865 			sh->bm_seq = conf->seq_flush + 1;
5866 			set_bit(STRIPE_BIT_DELAY, &sh->state);
5867 		}
5868 
5869 		set_bit(STRIPE_HANDLE, &sh->state);
5870 		clear_bit(STRIPE_DELAYED, &sh->state);
5871 		if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5872 			atomic_inc(&conf->preread_active_stripes);
5873 		release_stripe_plug(mddev, sh);
5874 	}
5875 
5876 	bio_endio(bi);
5877 }
5878 
5879 static bool ahead_of_reshape(struct mddev *mddev, sector_t sector,
5880 			     sector_t reshape_sector)
5881 {
5882 	return mddev->reshape_backwards ? sector < reshape_sector :
5883 					  sector >= reshape_sector;
5884 }
5885 
5886 static bool range_ahead_of_reshape(struct mddev *mddev, sector_t min,
5887 				   sector_t max, sector_t reshape_sector)
5888 {
5889 	return mddev->reshape_backwards ? max < reshape_sector :
5890 					  min >= reshape_sector;
5891 }
5892 
5893 static bool stripe_ahead_of_reshape(struct mddev *mddev, struct r5conf *conf,
5894 				    struct stripe_head *sh)
5895 {
5896 	sector_t max_sector = 0, min_sector = MaxSector;
5897 	bool ret = false;
5898 	int dd_idx;
5899 
5900 	for (dd_idx = 0; dd_idx < sh->disks; dd_idx++) {
5901 		if (dd_idx == sh->pd_idx)
5902 			continue;
5903 
5904 		min_sector = min(min_sector, sh->dev[dd_idx].sector);
5905 		max_sector = min(max_sector, sh->dev[dd_idx].sector);
5906 	}
5907 
5908 	spin_lock_irq(&conf->device_lock);
5909 
5910 	if (!range_ahead_of_reshape(mddev, min_sector, max_sector,
5911 				     conf->reshape_progress))
5912 		/* mismatch, need to try again */
5913 		ret = true;
5914 
5915 	spin_unlock_irq(&conf->device_lock);
5916 
5917 	return ret;
5918 }
5919 
5920 static int add_all_stripe_bios(struct r5conf *conf,
5921 		struct stripe_request_ctx *ctx, struct stripe_head *sh,
5922 		struct bio *bi, int forwrite, int previous)
5923 {
5924 	int dd_idx;
5925 	int ret = 1;
5926 
5927 	spin_lock_irq(&sh->stripe_lock);
5928 
5929 	for (dd_idx = 0; dd_idx < sh->disks; dd_idx++) {
5930 		struct r5dev *dev = &sh->dev[dd_idx];
5931 
5932 		if (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
5933 			continue;
5934 
5935 		if (dev->sector < ctx->first_sector ||
5936 		    dev->sector >= ctx->last_sector)
5937 			continue;
5938 
5939 		if (stripe_bio_overlaps(sh, bi, dd_idx, forwrite)) {
5940 			set_bit(R5_Overlap, &dev->flags);
5941 			ret = 0;
5942 			continue;
5943 		}
5944 	}
5945 
5946 	if (!ret)
5947 		goto out;
5948 
5949 	for (dd_idx = 0; dd_idx < sh->disks; dd_idx++) {
5950 		struct r5dev *dev = &sh->dev[dd_idx];
5951 
5952 		if (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
5953 			continue;
5954 
5955 		if (dev->sector < ctx->first_sector ||
5956 		    dev->sector >= ctx->last_sector)
5957 			continue;
5958 
5959 		__add_stripe_bio(sh, bi, dd_idx, forwrite, previous);
5960 		clear_bit((dev->sector - ctx->first_sector) >>
5961 			  RAID5_STRIPE_SHIFT(conf), ctx->sectors_to_do);
5962 	}
5963 
5964 out:
5965 	spin_unlock_irq(&sh->stripe_lock);
5966 	return ret;
5967 }
5968 
5969 static bool reshape_inprogress(struct mddev *mddev)
5970 {
5971 	return test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
5972 	       test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
5973 	       !test_bit(MD_RECOVERY_DONE, &mddev->recovery) &&
5974 	       !test_bit(MD_RECOVERY_INTR, &mddev->recovery);
5975 }
5976 
5977 static bool reshape_disabled(struct mddev *mddev)
5978 {
5979 	return is_md_suspended(mddev) || !md_is_rdwr(mddev);
5980 }
5981 
5982 static enum stripe_result make_stripe_request(struct mddev *mddev,
5983 		struct r5conf *conf, struct stripe_request_ctx *ctx,
5984 		sector_t logical_sector, struct bio *bi)
5985 {
5986 	const int rw = bio_data_dir(bi);
5987 	enum stripe_result ret;
5988 	struct stripe_head *sh;
5989 	sector_t new_sector;
5990 	int previous = 0, flags = 0;
5991 	int seq, dd_idx;
5992 
5993 	seq = read_seqcount_begin(&conf->gen_lock);
5994 
5995 	if (unlikely(conf->reshape_progress != MaxSector)) {
5996 		/*
5997 		 * Spinlock is needed as reshape_progress may be
5998 		 * 64bit on a 32bit platform, and so it might be
5999 		 * possible to see a half-updated value
6000 		 * Of course reshape_progress could change after
6001 		 * the lock is dropped, so once we get a reference
6002 		 * to the stripe that we think it is, we will have
6003 		 * to check again.
6004 		 */
6005 		spin_lock_irq(&conf->device_lock);
6006 		if (ahead_of_reshape(mddev, logical_sector,
6007 				     conf->reshape_progress)) {
6008 			previous = 1;
6009 		} else {
6010 			if (ahead_of_reshape(mddev, logical_sector,
6011 					     conf->reshape_safe)) {
6012 				spin_unlock_irq(&conf->device_lock);
6013 				ret = STRIPE_SCHEDULE_AND_RETRY;
6014 				goto out;
6015 			}
6016 		}
6017 		spin_unlock_irq(&conf->device_lock);
6018 	}
6019 
6020 	new_sector = raid5_compute_sector(conf, logical_sector, previous,
6021 					  &dd_idx, NULL);
6022 	pr_debug("raid456: %s, sector %llu logical %llu\n", __func__,
6023 		 new_sector, logical_sector);
6024 
6025 	if (previous)
6026 		flags |= R5_GAS_PREVIOUS;
6027 	if (bi->bi_opf & REQ_RAHEAD)
6028 		flags |= R5_GAS_NOBLOCK;
6029 	sh = raid5_get_active_stripe(conf, ctx, new_sector, flags);
6030 	if (unlikely(!sh)) {
6031 		/* cannot get stripe, just give-up */
6032 		bi->bi_status = BLK_STS_IOERR;
6033 		return STRIPE_FAIL;
6034 	}
6035 
6036 	if (unlikely(previous) &&
6037 	    stripe_ahead_of_reshape(mddev, conf, sh)) {
6038 		/*
6039 		 * Expansion moved on while waiting for a stripe.
6040 		 * Expansion could still move past after this
6041 		 * test, but as we are holding a reference to
6042 		 * 'sh', we know that if that happens,
6043 		 *  STRIPE_EXPANDING will get set and the expansion
6044 		 * won't proceed until we finish with the stripe.
6045 		 */
6046 		ret = STRIPE_SCHEDULE_AND_RETRY;
6047 		goto out_release;
6048 	}
6049 
6050 	if (read_seqcount_retry(&conf->gen_lock, seq)) {
6051 		/* Might have got the wrong stripe_head by accident */
6052 		ret = STRIPE_RETRY;
6053 		goto out_release;
6054 	}
6055 
6056 	if (test_bit(STRIPE_EXPANDING, &sh->state) ||
6057 	    !add_all_stripe_bios(conf, ctx, sh, bi, rw, previous)) {
6058 		/*
6059 		 * Stripe is busy expanding or add failed due to
6060 		 * overlap. Flush everything and wait a while.
6061 		 */
6062 		md_wakeup_thread(mddev->thread);
6063 		ret = STRIPE_SCHEDULE_AND_RETRY;
6064 		goto out_release;
6065 	}
6066 
6067 	if (stripe_can_batch(sh)) {
6068 		stripe_add_to_batch_list(conf, sh, ctx->batch_last);
6069 		if (ctx->batch_last)
6070 			raid5_release_stripe(ctx->batch_last);
6071 		atomic_inc(&sh->count);
6072 		ctx->batch_last = sh;
6073 	}
6074 
6075 	if (ctx->do_flush) {
6076 		set_bit(STRIPE_R5C_PREFLUSH, &sh->state);
6077 		/* we only need flush for one stripe */
6078 		ctx->do_flush = false;
6079 	}
6080 
6081 	set_bit(STRIPE_HANDLE, &sh->state);
6082 	clear_bit(STRIPE_DELAYED, &sh->state);
6083 	if ((!sh->batch_head || sh == sh->batch_head) &&
6084 	    (bi->bi_opf & REQ_SYNC) &&
6085 	    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
6086 		atomic_inc(&conf->preread_active_stripes);
6087 
6088 	release_stripe_plug(mddev, sh);
6089 	return STRIPE_SUCCESS;
6090 
6091 out_release:
6092 	raid5_release_stripe(sh);
6093 out:
6094 	if (ret == STRIPE_SCHEDULE_AND_RETRY && !reshape_inprogress(mddev) &&
6095 	    reshape_disabled(mddev)) {
6096 		bi->bi_status = BLK_STS_IOERR;
6097 		ret = STRIPE_FAIL;
6098 		pr_err("md/raid456:%s: io failed across reshape position while reshape can't make progress.\n",
6099 		       mdname(mddev));
6100 	}
6101 
6102 	return ret;
6103 }
6104 
6105 /*
6106  * If the bio covers multiple data disks, find sector within the bio that has
6107  * the lowest chunk offset in the first chunk.
6108  */
6109 static sector_t raid5_bio_lowest_chunk_sector(struct r5conf *conf,
6110 					      struct bio *bi)
6111 {
6112 	int sectors_per_chunk = conf->chunk_sectors;
6113 	int raid_disks = conf->raid_disks;
6114 	int dd_idx;
6115 	struct stripe_head sh;
6116 	unsigned int chunk_offset;
6117 	sector_t r_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
6118 	sector_t sector;
6119 
6120 	/* We pass in fake stripe_head to get back parity disk numbers */
6121 	sector = raid5_compute_sector(conf, r_sector, 0, &dd_idx, &sh);
6122 	chunk_offset = sector_div(sector, sectors_per_chunk);
6123 	if (sectors_per_chunk - chunk_offset >= bio_sectors(bi))
6124 		return r_sector;
6125 	/*
6126 	 * Bio crosses to the next data disk. Check whether it's in the same
6127 	 * chunk.
6128 	 */
6129 	dd_idx++;
6130 	while (dd_idx == sh.pd_idx || dd_idx == sh.qd_idx)
6131 		dd_idx++;
6132 	if (dd_idx >= raid_disks)
6133 		return r_sector;
6134 	return r_sector + sectors_per_chunk - chunk_offset;
6135 }
6136 
6137 static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
6138 {
6139 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
6140 	struct r5conf *conf = mddev->private;
6141 	sector_t logical_sector;
6142 	struct stripe_request_ctx ctx = {};
6143 	const int rw = bio_data_dir(bi);
6144 	enum stripe_result res;
6145 	int s, stripe_cnt;
6146 
6147 	if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
6148 		int ret = log_handle_flush_request(conf, bi);
6149 
6150 		if (ret == 0)
6151 			return true;
6152 		if (ret == -ENODEV) {
6153 			if (md_flush_request(mddev, bi))
6154 				return true;
6155 		}
6156 		/* ret == -EAGAIN, fallback */
6157 		/*
6158 		 * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
6159 		 * we need to flush journal device
6160 		 */
6161 		ctx.do_flush = bi->bi_opf & REQ_PREFLUSH;
6162 	}
6163 
6164 	if (!md_write_start(mddev, bi))
6165 		return false;
6166 	/*
6167 	 * If array is degraded, better not do chunk aligned read because
6168 	 * later we might have to read it again in order to reconstruct
6169 	 * data on failed drives.
6170 	 */
6171 	if (rw == READ && mddev->degraded == 0 &&
6172 	    mddev->reshape_position == MaxSector) {
6173 		bi = chunk_aligned_read(mddev, bi);
6174 		if (!bi)
6175 			return true;
6176 	}
6177 
6178 	if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) {
6179 		make_discard_request(mddev, bi);
6180 		md_write_end(mddev);
6181 		return true;
6182 	}
6183 
6184 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
6185 	ctx.first_sector = logical_sector;
6186 	ctx.last_sector = bio_end_sector(bi);
6187 	bi->bi_next = NULL;
6188 
6189 	stripe_cnt = DIV_ROUND_UP_SECTOR_T(ctx.last_sector - logical_sector,
6190 					   RAID5_STRIPE_SECTORS(conf));
6191 	bitmap_set(ctx.sectors_to_do, 0, stripe_cnt);
6192 
6193 	pr_debug("raid456: %s, logical %llu to %llu\n", __func__,
6194 		 bi->bi_iter.bi_sector, ctx.last_sector);
6195 
6196 	/* Bail out if conflicts with reshape and REQ_NOWAIT is set */
6197 	if ((bi->bi_opf & REQ_NOWAIT) &&
6198 	    (conf->reshape_progress != MaxSector) &&
6199 	    !ahead_of_reshape(mddev, logical_sector, conf->reshape_progress) &&
6200 	    ahead_of_reshape(mddev, logical_sector, conf->reshape_safe)) {
6201 		bio_wouldblock_error(bi);
6202 		if (rw == WRITE)
6203 			md_write_end(mddev);
6204 		return true;
6205 	}
6206 	md_account_bio(mddev, &bi);
6207 
6208 	/*
6209 	 * Lets start with the stripe with the lowest chunk offset in the first
6210 	 * chunk. That has the best chances of creating IOs adjacent to
6211 	 * previous IOs in case of sequential IO and thus creates the most
6212 	 * sequential IO pattern. We don't bother with the optimization when
6213 	 * reshaping as the performance benefit is not worth the complexity.
6214 	 */
6215 	if (likely(conf->reshape_progress == MaxSector))
6216 		logical_sector = raid5_bio_lowest_chunk_sector(conf, bi);
6217 	s = (logical_sector - ctx.first_sector) >> RAID5_STRIPE_SHIFT(conf);
6218 
6219 	add_wait_queue(&conf->wait_for_overlap, &wait);
6220 	while (1) {
6221 		res = make_stripe_request(mddev, conf, &ctx, logical_sector,
6222 					  bi);
6223 		if (res == STRIPE_FAIL)
6224 			break;
6225 
6226 		if (res == STRIPE_RETRY)
6227 			continue;
6228 
6229 		if (res == STRIPE_SCHEDULE_AND_RETRY) {
6230 			/*
6231 			 * Must release the reference to batch_last before
6232 			 * scheduling and waiting for work to be done,
6233 			 * otherwise the batch_last stripe head could prevent
6234 			 * raid5_activate_delayed() from making progress
6235 			 * and thus deadlocking.
6236 			 */
6237 			if (ctx.batch_last) {
6238 				raid5_release_stripe(ctx.batch_last);
6239 				ctx.batch_last = NULL;
6240 			}
6241 
6242 			wait_woken(&wait, TASK_UNINTERRUPTIBLE,
6243 				   MAX_SCHEDULE_TIMEOUT);
6244 			continue;
6245 		}
6246 
6247 		s = find_next_bit_wrap(ctx.sectors_to_do, stripe_cnt, s);
6248 		if (s == stripe_cnt)
6249 			break;
6250 
6251 		logical_sector = ctx.first_sector +
6252 			(s << RAID5_STRIPE_SHIFT(conf));
6253 	}
6254 	remove_wait_queue(&conf->wait_for_overlap, &wait);
6255 
6256 	if (ctx.batch_last)
6257 		raid5_release_stripe(ctx.batch_last);
6258 
6259 	if (rw == WRITE)
6260 		md_write_end(mddev);
6261 	bio_endio(bi);
6262 	return true;
6263 }
6264 
6265 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
6266 
6267 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
6268 {
6269 	/* reshaping is quite different to recovery/resync so it is
6270 	 * handled quite separately ... here.
6271 	 *
6272 	 * On each call to sync_request, we gather one chunk worth of
6273 	 * destination stripes and flag them as expanding.
6274 	 * Then we find all the source stripes and request reads.
6275 	 * As the reads complete, handle_stripe will copy the data
6276 	 * into the destination stripe and release that stripe.
6277 	 */
6278 	struct r5conf *conf = mddev->private;
6279 	struct stripe_head *sh;
6280 	struct md_rdev *rdev;
6281 	sector_t first_sector, last_sector;
6282 	int raid_disks = conf->previous_raid_disks;
6283 	int data_disks = raid_disks - conf->max_degraded;
6284 	int new_data_disks = conf->raid_disks - conf->max_degraded;
6285 	int i;
6286 	int dd_idx;
6287 	sector_t writepos, readpos, safepos;
6288 	sector_t stripe_addr;
6289 	int reshape_sectors;
6290 	struct list_head stripes;
6291 	sector_t retn;
6292 
6293 	if (sector_nr == 0) {
6294 		/* If restarting in the middle, skip the initial sectors */
6295 		if (mddev->reshape_backwards &&
6296 		    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
6297 			sector_nr = raid5_size(mddev, 0, 0)
6298 				- conf->reshape_progress;
6299 		} else if (mddev->reshape_backwards &&
6300 			   conf->reshape_progress == MaxSector) {
6301 			/* shouldn't happen, but just in case, finish up.*/
6302 			sector_nr = MaxSector;
6303 		} else if (!mddev->reshape_backwards &&
6304 			   conf->reshape_progress > 0)
6305 			sector_nr = conf->reshape_progress;
6306 		sector_div(sector_nr, new_data_disks);
6307 		if (sector_nr) {
6308 			mddev->curr_resync_completed = sector_nr;
6309 			sysfs_notify_dirent_safe(mddev->sysfs_completed);
6310 			*skipped = 1;
6311 			retn = sector_nr;
6312 			goto finish;
6313 		}
6314 	}
6315 
6316 	/* We need to process a full chunk at a time.
6317 	 * If old and new chunk sizes differ, we need to process the
6318 	 * largest of these
6319 	 */
6320 
6321 	reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
6322 
6323 	/* We update the metadata at least every 10 seconds, or when
6324 	 * the data about to be copied would over-write the source of
6325 	 * the data at the front of the range.  i.e. one new_stripe
6326 	 * along from reshape_progress new_maps to after where
6327 	 * reshape_safe old_maps to
6328 	 */
6329 	writepos = conf->reshape_progress;
6330 	sector_div(writepos, new_data_disks);
6331 	readpos = conf->reshape_progress;
6332 	sector_div(readpos, data_disks);
6333 	safepos = conf->reshape_safe;
6334 	sector_div(safepos, data_disks);
6335 	if (mddev->reshape_backwards) {
6336 		BUG_ON(writepos < reshape_sectors);
6337 		writepos -= reshape_sectors;
6338 		readpos += reshape_sectors;
6339 		safepos += reshape_sectors;
6340 	} else {
6341 		writepos += reshape_sectors;
6342 		/* readpos and safepos are worst-case calculations.
6343 		 * A negative number is overly pessimistic, and causes
6344 		 * obvious problems for unsigned storage.  So clip to 0.
6345 		 */
6346 		readpos -= min_t(sector_t, reshape_sectors, readpos);
6347 		safepos -= min_t(sector_t, reshape_sectors, safepos);
6348 	}
6349 
6350 	/* Having calculated the 'writepos' possibly use it
6351 	 * to set 'stripe_addr' which is where we will write to.
6352 	 */
6353 	if (mddev->reshape_backwards) {
6354 		BUG_ON(conf->reshape_progress == 0);
6355 		stripe_addr = writepos;
6356 		BUG_ON((mddev->dev_sectors &
6357 			~((sector_t)reshape_sectors - 1))
6358 		       - reshape_sectors - stripe_addr
6359 		       != sector_nr);
6360 	} else {
6361 		BUG_ON(writepos != sector_nr + reshape_sectors);
6362 		stripe_addr = sector_nr;
6363 	}
6364 
6365 	/* 'writepos' is the most advanced device address we might write.
6366 	 * 'readpos' is the least advanced device address we might read.
6367 	 * 'safepos' is the least address recorded in the metadata as having
6368 	 *     been reshaped.
6369 	 * If there is a min_offset_diff, these are adjusted either by
6370 	 * increasing the safepos/readpos if diff is negative, or
6371 	 * increasing writepos if diff is positive.
6372 	 * If 'readpos' is then behind 'writepos', there is no way that we can
6373 	 * ensure safety in the face of a crash - that must be done by userspace
6374 	 * making a backup of the data.  So in that case there is no particular
6375 	 * rush to update metadata.
6376 	 * Otherwise if 'safepos' is behind 'writepos', then we really need to
6377 	 * update the metadata to advance 'safepos' to match 'readpos' so that
6378 	 * we can be safe in the event of a crash.
6379 	 * So we insist on updating metadata if safepos is behind writepos and
6380 	 * readpos is beyond writepos.
6381 	 * In any case, update the metadata every 10 seconds.
6382 	 * Maybe that number should be configurable, but I'm not sure it is
6383 	 * worth it.... maybe it could be a multiple of safemode_delay???
6384 	 */
6385 	if (conf->min_offset_diff < 0) {
6386 		safepos += -conf->min_offset_diff;
6387 		readpos += -conf->min_offset_diff;
6388 	} else
6389 		writepos += conf->min_offset_diff;
6390 
6391 	if ((mddev->reshape_backwards
6392 	     ? (safepos > writepos && readpos < writepos)
6393 	     : (safepos < writepos && readpos > writepos)) ||
6394 	    time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
6395 		/* Cannot proceed until we've updated the superblock... */
6396 		wait_event(conf->wait_for_overlap,
6397 			   atomic_read(&conf->reshape_stripes)==0
6398 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
6399 		if (atomic_read(&conf->reshape_stripes) != 0)
6400 			return 0;
6401 		mddev->reshape_position = conf->reshape_progress;
6402 		mddev->curr_resync_completed = sector_nr;
6403 		if (!mddev->reshape_backwards)
6404 			/* Can update recovery_offset */
6405 			rdev_for_each(rdev, mddev)
6406 				if (rdev->raid_disk >= 0 &&
6407 				    !test_bit(Journal, &rdev->flags) &&
6408 				    !test_bit(In_sync, &rdev->flags) &&
6409 				    rdev->recovery_offset < sector_nr)
6410 					rdev->recovery_offset = sector_nr;
6411 
6412 		conf->reshape_checkpoint = jiffies;
6413 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
6414 		md_wakeup_thread(mddev->thread);
6415 		wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
6416 			   test_bit(MD_RECOVERY_INTR, &mddev->recovery));
6417 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
6418 			return 0;
6419 		spin_lock_irq(&conf->device_lock);
6420 		conf->reshape_safe = mddev->reshape_position;
6421 		spin_unlock_irq(&conf->device_lock);
6422 		wake_up(&conf->wait_for_overlap);
6423 		sysfs_notify_dirent_safe(mddev->sysfs_completed);
6424 	}
6425 
6426 	INIT_LIST_HEAD(&stripes);
6427 	for (i = 0; i < reshape_sectors; i += RAID5_STRIPE_SECTORS(conf)) {
6428 		int j;
6429 		int skipped_disk = 0;
6430 		sh = raid5_get_active_stripe(conf, NULL, stripe_addr+i,
6431 					     R5_GAS_NOQUIESCE);
6432 		set_bit(STRIPE_EXPANDING, &sh->state);
6433 		atomic_inc(&conf->reshape_stripes);
6434 		/* If any of this stripe is beyond the end of the old
6435 		 * array, then we need to zero those blocks
6436 		 */
6437 		for (j=sh->disks; j--;) {
6438 			sector_t s;
6439 			if (j == sh->pd_idx)
6440 				continue;
6441 			if (conf->level == 6 &&
6442 			    j == sh->qd_idx)
6443 				continue;
6444 			s = raid5_compute_blocknr(sh, j, 0);
6445 			if (s < raid5_size(mddev, 0, 0)) {
6446 				skipped_disk = 1;
6447 				continue;
6448 			}
6449 			memset(page_address(sh->dev[j].page), 0, RAID5_STRIPE_SIZE(conf));
6450 			set_bit(R5_Expanded, &sh->dev[j].flags);
6451 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
6452 		}
6453 		if (!skipped_disk) {
6454 			set_bit(STRIPE_EXPAND_READY, &sh->state);
6455 			set_bit(STRIPE_HANDLE, &sh->state);
6456 		}
6457 		list_add(&sh->lru, &stripes);
6458 	}
6459 	spin_lock_irq(&conf->device_lock);
6460 	if (mddev->reshape_backwards)
6461 		conf->reshape_progress -= reshape_sectors * new_data_disks;
6462 	else
6463 		conf->reshape_progress += reshape_sectors * new_data_disks;
6464 	spin_unlock_irq(&conf->device_lock);
6465 	/* Ok, those stripe are ready. We can start scheduling
6466 	 * reads on the source stripes.
6467 	 * The source stripes are determined by mapping the first and last
6468 	 * block on the destination stripes.
6469 	 */
6470 	first_sector =
6471 		raid5_compute_sector(conf, stripe_addr*(new_data_disks),
6472 				     1, &dd_idx, NULL);
6473 	last_sector =
6474 		raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
6475 					    * new_data_disks - 1),
6476 				     1, &dd_idx, NULL);
6477 	if (last_sector >= mddev->dev_sectors)
6478 		last_sector = mddev->dev_sectors - 1;
6479 	while (first_sector <= last_sector) {
6480 		sh = raid5_get_active_stripe(conf, NULL, first_sector,
6481 				R5_GAS_PREVIOUS | R5_GAS_NOQUIESCE);
6482 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
6483 		set_bit(STRIPE_HANDLE, &sh->state);
6484 		raid5_release_stripe(sh);
6485 		first_sector += RAID5_STRIPE_SECTORS(conf);
6486 	}
6487 	/* Now that the sources are clearly marked, we can release
6488 	 * the destination stripes
6489 	 */
6490 	while (!list_empty(&stripes)) {
6491 		sh = list_entry(stripes.next, struct stripe_head, lru);
6492 		list_del_init(&sh->lru);
6493 		raid5_release_stripe(sh);
6494 	}
6495 	/* If this takes us to the resync_max point where we have to pause,
6496 	 * then we need to write out the superblock.
6497 	 */
6498 	sector_nr += reshape_sectors;
6499 	retn = reshape_sectors;
6500 finish:
6501 	if (mddev->curr_resync_completed > mddev->resync_max ||
6502 	    (sector_nr - mddev->curr_resync_completed) * 2
6503 	    >= mddev->resync_max - mddev->curr_resync_completed) {
6504 		/* Cannot proceed until we've updated the superblock... */
6505 		wait_event(conf->wait_for_overlap,
6506 			   atomic_read(&conf->reshape_stripes) == 0
6507 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
6508 		if (atomic_read(&conf->reshape_stripes) != 0)
6509 			goto ret;
6510 		mddev->reshape_position = conf->reshape_progress;
6511 		mddev->curr_resync_completed = sector_nr;
6512 		if (!mddev->reshape_backwards)
6513 			/* Can update recovery_offset */
6514 			rdev_for_each(rdev, mddev)
6515 				if (rdev->raid_disk >= 0 &&
6516 				    !test_bit(Journal, &rdev->flags) &&
6517 				    !test_bit(In_sync, &rdev->flags) &&
6518 				    rdev->recovery_offset < sector_nr)
6519 					rdev->recovery_offset = sector_nr;
6520 		conf->reshape_checkpoint = jiffies;
6521 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
6522 		md_wakeup_thread(mddev->thread);
6523 		wait_event(mddev->sb_wait,
6524 			   !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)
6525 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
6526 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
6527 			goto ret;
6528 		spin_lock_irq(&conf->device_lock);
6529 		conf->reshape_safe = mddev->reshape_position;
6530 		spin_unlock_irq(&conf->device_lock);
6531 		wake_up(&conf->wait_for_overlap);
6532 		sysfs_notify_dirent_safe(mddev->sysfs_completed);
6533 	}
6534 ret:
6535 	return retn;
6536 }
6537 
6538 static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_nr,
6539 					  int *skipped)
6540 {
6541 	struct r5conf *conf = mddev->private;
6542 	struct stripe_head *sh;
6543 	sector_t max_sector = mddev->dev_sectors;
6544 	sector_t sync_blocks;
6545 	int still_degraded = 0;
6546 	int i;
6547 
6548 	if (sector_nr >= max_sector) {
6549 		/* just being told to finish up .. nothing much to do */
6550 
6551 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
6552 			end_reshape(conf);
6553 			return 0;
6554 		}
6555 
6556 		if (mddev->curr_resync < max_sector) /* aborted */
6557 			md_bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
6558 					   &sync_blocks, 1);
6559 		else /* completed sync */
6560 			conf->fullsync = 0;
6561 		md_bitmap_close_sync(mddev->bitmap);
6562 
6563 		return 0;
6564 	}
6565 
6566 	/* Allow raid5_quiesce to complete */
6567 	wait_event(conf->wait_for_overlap, conf->quiesce != 2);
6568 
6569 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
6570 		return reshape_request(mddev, sector_nr, skipped);
6571 
6572 	/* No need to check resync_max as we never do more than one
6573 	 * stripe, and as resync_max will always be on a chunk boundary,
6574 	 * if the check in md_do_sync didn't fire, there is no chance
6575 	 * of overstepping resync_max here
6576 	 */
6577 
6578 	/* if there is too many failed drives and we are trying
6579 	 * to resync, then assert that we are finished, because there is
6580 	 * nothing we can do.
6581 	 */
6582 	if (mddev->degraded >= conf->max_degraded &&
6583 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
6584 		sector_t rv = mddev->dev_sectors - sector_nr;
6585 		*skipped = 1;
6586 		return rv;
6587 	}
6588 	if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
6589 	    !conf->fullsync &&
6590 	    !md_bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
6591 	    sync_blocks >= RAID5_STRIPE_SECTORS(conf)) {
6592 		/* we can skip this block, and probably more */
6593 		do_div(sync_blocks, RAID5_STRIPE_SECTORS(conf));
6594 		*skipped = 1;
6595 		/* keep things rounded to whole stripes */
6596 		return sync_blocks * RAID5_STRIPE_SECTORS(conf);
6597 	}
6598 
6599 	md_bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
6600 
6601 	sh = raid5_get_active_stripe(conf, NULL, sector_nr,
6602 				     R5_GAS_NOBLOCK);
6603 	if (sh == NULL) {
6604 		sh = raid5_get_active_stripe(conf, NULL, sector_nr, 0);
6605 		/* make sure we don't swamp the stripe cache if someone else
6606 		 * is trying to get access
6607 		 */
6608 		schedule_timeout_uninterruptible(1);
6609 	}
6610 	/* Need to check if array will still be degraded after recovery/resync
6611 	 * Note in case of > 1 drive failures it's possible we're rebuilding
6612 	 * one drive while leaving another faulty drive in array.
6613 	 */
6614 	rcu_read_lock();
6615 	for (i = 0; i < conf->raid_disks; i++) {
6616 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
6617 
6618 		if (rdev == NULL || test_bit(Faulty, &rdev->flags))
6619 			still_degraded = 1;
6620 	}
6621 	rcu_read_unlock();
6622 
6623 	md_bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
6624 
6625 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
6626 	set_bit(STRIPE_HANDLE, &sh->state);
6627 
6628 	raid5_release_stripe(sh);
6629 
6630 	return RAID5_STRIPE_SECTORS(conf);
6631 }
6632 
6633 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio,
6634 			       unsigned int offset)
6635 {
6636 	/* We may not be able to submit a whole bio at once as there
6637 	 * may not be enough stripe_heads available.
6638 	 * We cannot pre-allocate enough stripe_heads as we may need
6639 	 * more than exist in the cache (if we allow ever large chunks).
6640 	 * So we do one stripe head at a time and record in
6641 	 * ->bi_hw_segments how many have been done.
6642 	 *
6643 	 * We *know* that this entire raid_bio is in one chunk, so
6644 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
6645 	 */
6646 	struct stripe_head *sh;
6647 	int dd_idx;
6648 	sector_t sector, logical_sector, last_sector;
6649 	int scnt = 0;
6650 	int handled = 0;
6651 
6652 	logical_sector = raid_bio->bi_iter.bi_sector &
6653 		~((sector_t)RAID5_STRIPE_SECTORS(conf)-1);
6654 	sector = raid5_compute_sector(conf, logical_sector,
6655 				      0, &dd_idx, NULL);
6656 	last_sector = bio_end_sector(raid_bio);
6657 
6658 	for (; logical_sector < last_sector;
6659 	     logical_sector += RAID5_STRIPE_SECTORS(conf),
6660 		     sector += RAID5_STRIPE_SECTORS(conf),
6661 		     scnt++) {
6662 
6663 		if (scnt < offset)
6664 			/* already done this stripe */
6665 			continue;
6666 
6667 		sh = raid5_get_active_stripe(conf, NULL, sector,
6668 				R5_GAS_NOBLOCK | R5_GAS_NOQUIESCE);
6669 		if (!sh) {
6670 			/* failed to get a stripe - must wait */
6671 			conf->retry_read_aligned = raid_bio;
6672 			conf->retry_read_offset = scnt;
6673 			return handled;
6674 		}
6675 
6676 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
6677 			raid5_release_stripe(sh);
6678 			conf->retry_read_aligned = raid_bio;
6679 			conf->retry_read_offset = scnt;
6680 			return handled;
6681 		}
6682 
6683 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
6684 		handle_stripe(sh);
6685 		raid5_release_stripe(sh);
6686 		handled++;
6687 	}
6688 
6689 	bio_endio(raid_bio);
6690 
6691 	if (atomic_dec_and_test(&conf->active_aligned_reads))
6692 		wake_up(&conf->wait_for_quiescent);
6693 	return handled;
6694 }
6695 
6696 static int handle_active_stripes(struct r5conf *conf, int group,
6697 				 struct r5worker *worker,
6698 				 struct list_head *temp_inactive_list)
6699 		__must_hold(&conf->device_lock)
6700 {
6701 	struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
6702 	int i, batch_size = 0, hash;
6703 	bool release_inactive = false;
6704 
6705 	while (batch_size < MAX_STRIPE_BATCH &&
6706 			(sh = __get_priority_stripe(conf, group)) != NULL)
6707 		batch[batch_size++] = sh;
6708 
6709 	if (batch_size == 0) {
6710 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6711 			if (!list_empty(temp_inactive_list + i))
6712 				break;
6713 		if (i == NR_STRIPE_HASH_LOCKS) {
6714 			spin_unlock_irq(&conf->device_lock);
6715 			log_flush_stripe_to_raid(conf);
6716 			spin_lock_irq(&conf->device_lock);
6717 			return batch_size;
6718 		}
6719 		release_inactive = true;
6720 	}
6721 	spin_unlock_irq(&conf->device_lock);
6722 
6723 	release_inactive_stripe_list(conf, temp_inactive_list,
6724 				     NR_STRIPE_HASH_LOCKS);
6725 
6726 	r5l_flush_stripe_to_raid(conf->log);
6727 	if (release_inactive) {
6728 		spin_lock_irq(&conf->device_lock);
6729 		return 0;
6730 	}
6731 
6732 	for (i = 0; i < batch_size; i++)
6733 		handle_stripe(batch[i]);
6734 	log_write_stripe_run(conf);
6735 
6736 	cond_resched();
6737 
6738 	spin_lock_irq(&conf->device_lock);
6739 	for (i = 0; i < batch_size; i++) {
6740 		hash = batch[i]->hash_lock_index;
6741 		__release_stripe(conf, batch[i], &temp_inactive_list[hash]);
6742 	}
6743 	return batch_size;
6744 }
6745 
6746 static void raid5_do_work(struct work_struct *work)
6747 {
6748 	struct r5worker *worker = container_of(work, struct r5worker, work);
6749 	struct r5worker_group *group = worker->group;
6750 	struct r5conf *conf = group->conf;
6751 	struct mddev *mddev = conf->mddev;
6752 	int group_id = group - conf->worker_groups;
6753 	int handled;
6754 	struct blk_plug plug;
6755 
6756 	pr_debug("+++ raid5worker active\n");
6757 
6758 	blk_start_plug(&plug);
6759 	handled = 0;
6760 	spin_lock_irq(&conf->device_lock);
6761 	while (1) {
6762 		int batch_size, released;
6763 
6764 		released = release_stripe_list(conf, worker->temp_inactive_list);
6765 
6766 		batch_size = handle_active_stripes(conf, group_id, worker,
6767 						   worker->temp_inactive_list);
6768 		worker->working = false;
6769 		if (!batch_size && !released)
6770 			break;
6771 		handled += batch_size;
6772 		wait_event_lock_irq(mddev->sb_wait,
6773 			!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags),
6774 			conf->device_lock);
6775 	}
6776 	pr_debug("%d stripes handled\n", handled);
6777 
6778 	spin_unlock_irq(&conf->device_lock);
6779 
6780 	flush_deferred_bios(conf);
6781 
6782 	r5l_flush_stripe_to_raid(conf->log);
6783 
6784 	async_tx_issue_pending_all();
6785 	blk_finish_plug(&plug);
6786 
6787 	pr_debug("--- raid5worker inactive\n");
6788 }
6789 
6790 /*
6791  * This is our raid5 kernel thread.
6792  *
6793  * We scan the hash table for stripes which can be handled now.
6794  * During the scan, completed stripes are saved for us by the interrupt
6795  * handler, so that they will not have to wait for our next wakeup.
6796  */
6797 static void raid5d(struct md_thread *thread)
6798 {
6799 	struct mddev *mddev = thread->mddev;
6800 	struct r5conf *conf = mddev->private;
6801 	int handled;
6802 	struct blk_plug plug;
6803 
6804 	pr_debug("+++ raid5d active\n");
6805 
6806 	md_check_recovery(mddev);
6807 
6808 	blk_start_plug(&plug);
6809 	handled = 0;
6810 	spin_lock_irq(&conf->device_lock);
6811 	while (1) {
6812 		struct bio *bio;
6813 		int batch_size, released;
6814 		unsigned int offset;
6815 
6816 		released = release_stripe_list(conf, conf->temp_inactive_list);
6817 		if (released)
6818 			clear_bit(R5_DID_ALLOC, &conf->cache_state);
6819 
6820 		if (
6821 		    !list_empty(&conf->bitmap_list)) {
6822 			/* Now is a good time to flush some bitmap updates */
6823 			conf->seq_flush++;
6824 			spin_unlock_irq(&conf->device_lock);
6825 			md_bitmap_unplug(mddev->bitmap);
6826 			spin_lock_irq(&conf->device_lock);
6827 			conf->seq_write = conf->seq_flush;
6828 			activate_bit_delay(conf, conf->temp_inactive_list);
6829 		}
6830 		raid5_activate_delayed(conf);
6831 
6832 		while ((bio = remove_bio_from_retry(conf, &offset))) {
6833 			int ok;
6834 			spin_unlock_irq(&conf->device_lock);
6835 			ok = retry_aligned_read(conf, bio, offset);
6836 			spin_lock_irq(&conf->device_lock);
6837 			if (!ok)
6838 				break;
6839 			handled++;
6840 		}
6841 
6842 		batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
6843 						   conf->temp_inactive_list);
6844 		if (!batch_size && !released)
6845 			break;
6846 		handled += batch_size;
6847 
6848 		if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
6849 			spin_unlock_irq(&conf->device_lock);
6850 			md_check_recovery(mddev);
6851 			spin_lock_irq(&conf->device_lock);
6852 
6853 			/*
6854 			 * Waiting on MD_SB_CHANGE_PENDING below may deadlock
6855 			 * seeing md_check_recovery() is needed to clear
6856 			 * the flag when using mdmon.
6857 			 */
6858 			continue;
6859 		}
6860 
6861 		wait_event_lock_irq(mddev->sb_wait,
6862 			!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags),
6863 			conf->device_lock);
6864 	}
6865 	pr_debug("%d stripes handled\n", handled);
6866 
6867 	spin_unlock_irq(&conf->device_lock);
6868 	if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
6869 	    mutex_trylock(&conf->cache_size_mutex)) {
6870 		grow_one_stripe(conf, __GFP_NOWARN);
6871 		/* Set flag even if allocation failed.  This helps
6872 		 * slow down allocation requests when mem is short
6873 		 */
6874 		set_bit(R5_DID_ALLOC, &conf->cache_state);
6875 		mutex_unlock(&conf->cache_size_mutex);
6876 	}
6877 
6878 	flush_deferred_bios(conf);
6879 
6880 	r5l_flush_stripe_to_raid(conf->log);
6881 
6882 	async_tx_issue_pending_all();
6883 	blk_finish_plug(&plug);
6884 
6885 	pr_debug("--- raid5d inactive\n");
6886 }
6887 
6888 static ssize_t
6889 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
6890 {
6891 	struct r5conf *conf;
6892 	int ret = 0;
6893 	spin_lock(&mddev->lock);
6894 	conf = mddev->private;
6895 	if (conf)
6896 		ret = sprintf(page, "%d\n", conf->min_nr_stripes);
6897 	spin_unlock(&mddev->lock);
6898 	return ret;
6899 }
6900 
6901 int
6902 raid5_set_cache_size(struct mddev *mddev, int size)
6903 {
6904 	int result = 0;
6905 	struct r5conf *conf = mddev->private;
6906 
6907 	if (size <= 16 || size > 32768)
6908 		return -EINVAL;
6909 
6910 	conf->min_nr_stripes = size;
6911 	mutex_lock(&conf->cache_size_mutex);
6912 	while (size < conf->max_nr_stripes &&
6913 	       drop_one_stripe(conf))
6914 		;
6915 	mutex_unlock(&conf->cache_size_mutex);
6916 
6917 	md_allow_write(mddev);
6918 
6919 	mutex_lock(&conf->cache_size_mutex);
6920 	while (size > conf->max_nr_stripes)
6921 		if (!grow_one_stripe(conf, GFP_KERNEL)) {
6922 			conf->min_nr_stripes = conf->max_nr_stripes;
6923 			result = -ENOMEM;
6924 			break;
6925 		}
6926 	mutex_unlock(&conf->cache_size_mutex);
6927 
6928 	return result;
6929 }
6930 EXPORT_SYMBOL(raid5_set_cache_size);
6931 
6932 static ssize_t
6933 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6934 {
6935 	struct r5conf *conf;
6936 	unsigned long new;
6937 	int err;
6938 
6939 	if (len >= PAGE_SIZE)
6940 		return -EINVAL;
6941 	if (kstrtoul(page, 10, &new))
6942 		return -EINVAL;
6943 	err = mddev_lock(mddev);
6944 	if (err)
6945 		return err;
6946 	conf = mddev->private;
6947 	if (!conf)
6948 		err = -ENODEV;
6949 	else
6950 		err = raid5_set_cache_size(mddev, new);
6951 	mddev_unlock(mddev);
6952 
6953 	return err ?: len;
6954 }
6955 
6956 static struct md_sysfs_entry
6957 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6958 				raid5_show_stripe_cache_size,
6959 				raid5_store_stripe_cache_size);
6960 
6961 static ssize_t
6962 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6963 {
6964 	struct r5conf *conf = mddev->private;
6965 	if (conf)
6966 		return sprintf(page, "%d\n", conf->rmw_level);
6967 	else
6968 		return 0;
6969 }
6970 
6971 static ssize_t
6972 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6973 {
6974 	struct r5conf *conf = mddev->private;
6975 	unsigned long new;
6976 
6977 	if (!conf)
6978 		return -ENODEV;
6979 
6980 	if (len >= PAGE_SIZE)
6981 		return -EINVAL;
6982 
6983 	if (kstrtoul(page, 10, &new))
6984 		return -EINVAL;
6985 
6986 	if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6987 		return -EINVAL;
6988 
6989 	if (new != PARITY_DISABLE_RMW &&
6990 	    new != PARITY_ENABLE_RMW &&
6991 	    new != PARITY_PREFER_RMW)
6992 		return -EINVAL;
6993 
6994 	conf->rmw_level = new;
6995 	return len;
6996 }
6997 
6998 static struct md_sysfs_entry
6999 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
7000 			 raid5_show_rmw_level,
7001 			 raid5_store_rmw_level);
7002 
7003 static ssize_t
7004 raid5_show_stripe_size(struct mddev  *mddev, char *page)
7005 {
7006 	struct r5conf *conf;
7007 	int ret = 0;
7008 
7009 	spin_lock(&mddev->lock);
7010 	conf = mddev->private;
7011 	if (conf)
7012 		ret = sprintf(page, "%lu\n", RAID5_STRIPE_SIZE(conf));
7013 	spin_unlock(&mddev->lock);
7014 	return ret;
7015 }
7016 
7017 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
7018 static ssize_t
7019 raid5_store_stripe_size(struct mddev  *mddev, const char *page, size_t len)
7020 {
7021 	struct r5conf *conf;
7022 	unsigned long new;
7023 	int err;
7024 	int size;
7025 
7026 	if (len >= PAGE_SIZE)
7027 		return -EINVAL;
7028 	if (kstrtoul(page, 10, &new))
7029 		return -EINVAL;
7030 
7031 	/*
7032 	 * The value should not be bigger than PAGE_SIZE. It requires to
7033 	 * be multiple of DEFAULT_STRIPE_SIZE and the value should be power
7034 	 * of two.
7035 	 */
7036 	if (new % DEFAULT_STRIPE_SIZE != 0 ||
7037 			new > PAGE_SIZE || new == 0 ||
7038 			new != roundup_pow_of_two(new))
7039 		return -EINVAL;
7040 
7041 	err = mddev_lock(mddev);
7042 	if (err)
7043 		return err;
7044 
7045 	conf = mddev->private;
7046 	if (!conf) {
7047 		err = -ENODEV;
7048 		goto out_unlock;
7049 	}
7050 
7051 	if (new == conf->stripe_size)
7052 		goto out_unlock;
7053 
7054 	pr_debug("md/raid: change stripe_size from %lu to %lu\n",
7055 			conf->stripe_size, new);
7056 
7057 	if (mddev->sync_thread ||
7058 		test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
7059 		mddev->reshape_position != MaxSector ||
7060 		mddev->sysfs_active) {
7061 		err = -EBUSY;
7062 		goto out_unlock;
7063 	}
7064 
7065 	mddev_suspend(mddev);
7066 	mutex_lock(&conf->cache_size_mutex);
7067 	size = conf->max_nr_stripes;
7068 
7069 	shrink_stripes(conf);
7070 
7071 	conf->stripe_size = new;
7072 	conf->stripe_shift = ilog2(new) - 9;
7073 	conf->stripe_sectors = new >> 9;
7074 	if (grow_stripes(conf, size)) {
7075 		pr_warn("md/raid:%s: couldn't allocate buffers\n",
7076 				mdname(mddev));
7077 		err = -ENOMEM;
7078 	}
7079 	mutex_unlock(&conf->cache_size_mutex);
7080 	mddev_resume(mddev);
7081 
7082 out_unlock:
7083 	mddev_unlock(mddev);
7084 	return err ?: len;
7085 }
7086 
7087 static struct md_sysfs_entry
7088 raid5_stripe_size = __ATTR(stripe_size, 0644,
7089 			 raid5_show_stripe_size,
7090 			 raid5_store_stripe_size);
7091 #else
7092 static struct md_sysfs_entry
7093 raid5_stripe_size = __ATTR(stripe_size, 0444,
7094 			 raid5_show_stripe_size,
7095 			 NULL);
7096 #endif
7097 
7098 static ssize_t
7099 raid5_show_preread_threshold(struct mddev *mddev, char *page)
7100 {
7101 	struct r5conf *conf;
7102 	int ret = 0;
7103 	spin_lock(&mddev->lock);
7104 	conf = mddev->private;
7105 	if (conf)
7106 		ret = sprintf(page, "%d\n", conf->bypass_threshold);
7107 	spin_unlock(&mddev->lock);
7108 	return ret;
7109 }
7110 
7111 static ssize_t
7112 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
7113 {
7114 	struct r5conf *conf;
7115 	unsigned long new;
7116 	int err;
7117 
7118 	if (len >= PAGE_SIZE)
7119 		return -EINVAL;
7120 	if (kstrtoul(page, 10, &new))
7121 		return -EINVAL;
7122 
7123 	err = mddev_lock(mddev);
7124 	if (err)
7125 		return err;
7126 	conf = mddev->private;
7127 	if (!conf)
7128 		err = -ENODEV;
7129 	else if (new > conf->min_nr_stripes)
7130 		err = -EINVAL;
7131 	else
7132 		conf->bypass_threshold = new;
7133 	mddev_unlock(mddev);
7134 	return err ?: len;
7135 }
7136 
7137 static struct md_sysfs_entry
7138 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
7139 					S_IRUGO | S_IWUSR,
7140 					raid5_show_preread_threshold,
7141 					raid5_store_preread_threshold);
7142 
7143 static ssize_t
7144 raid5_show_skip_copy(struct mddev *mddev, char *page)
7145 {
7146 	struct r5conf *conf;
7147 	int ret = 0;
7148 	spin_lock(&mddev->lock);
7149 	conf = mddev->private;
7150 	if (conf)
7151 		ret = sprintf(page, "%d\n", conf->skip_copy);
7152 	spin_unlock(&mddev->lock);
7153 	return ret;
7154 }
7155 
7156 static ssize_t
7157 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
7158 {
7159 	struct r5conf *conf;
7160 	unsigned long new;
7161 	int err;
7162 
7163 	if (len >= PAGE_SIZE)
7164 		return -EINVAL;
7165 	if (kstrtoul(page, 10, &new))
7166 		return -EINVAL;
7167 	new = !!new;
7168 
7169 	err = mddev_lock(mddev);
7170 	if (err)
7171 		return err;
7172 	conf = mddev->private;
7173 	if (!conf)
7174 		err = -ENODEV;
7175 	else if (new != conf->skip_copy) {
7176 		struct request_queue *q = mddev->queue;
7177 
7178 		mddev_suspend(mddev);
7179 		conf->skip_copy = new;
7180 		if (new)
7181 			blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, q);
7182 		else
7183 			blk_queue_flag_clear(QUEUE_FLAG_STABLE_WRITES, q);
7184 		mddev_resume(mddev);
7185 	}
7186 	mddev_unlock(mddev);
7187 	return err ?: len;
7188 }
7189 
7190 static struct md_sysfs_entry
7191 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
7192 					raid5_show_skip_copy,
7193 					raid5_store_skip_copy);
7194 
7195 static ssize_t
7196 stripe_cache_active_show(struct mddev *mddev, char *page)
7197 {
7198 	struct r5conf *conf = mddev->private;
7199 	if (conf)
7200 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
7201 	else
7202 		return 0;
7203 }
7204 
7205 static struct md_sysfs_entry
7206 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
7207 
7208 static ssize_t
7209 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
7210 {
7211 	struct r5conf *conf;
7212 	int ret = 0;
7213 	spin_lock(&mddev->lock);
7214 	conf = mddev->private;
7215 	if (conf)
7216 		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
7217 	spin_unlock(&mddev->lock);
7218 	return ret;
7219 }
7220 
7221 static int alloc_thread_groups(struct r5conf *conf, int cnt,
7222 			       int *group_cnt,
7223 			       struct r5worker_group **worker_groups);
7224 static ssize_t
7225 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
7226 {
7227 	struct r5conf *conf;
7228 	unsigned int new;
7229 	int err;
7230 	struct r5worker_group *new_groups, *old_groups;
7231 	int group_cnt;
7232 
7233 	if (len >= PAGE_SIZE)
7234 		return -EINVAL;
7235 	if (kstrtouint(page, 10, &new))
7236 		return -EINVAL;
7237 	/* 8192 should be big enough */
7238 	if (new > 8192)
7239 		return -EINVAL;
7240 
7241 	err = mddev_lock(mddev);
7242 	if (err)
7243 		return err;
7244 	conf = mddev->private;
7245 	if (!conf)
7246 		err = -ENODEV;
7247 	else if (new != conf->worker_cnt_per_group) {
7248 		mddev_suspend(mddev);
7249 
7250 		old_groups = conf->worker_groups;
7251 		if (old_groups)
7252 			flush_workqueue(raid5_wq);
7253 
7254 		err = alloc_thread_groups(conf, new, &group_cnt, &new_groups);
7255 		if (!err) {
7256 			spin_lock_irq(&conf->device_lock);
7257 			conf->group_cnt = group_cnt;
7258 			conf->worker_cnt_per_group = new;
7259 			conf->worker_groups = new_groups;
7260 			spin_unlock_irq(&conf->device_lock);
7261 
7262 			if (old_groups)
7263 				kfree(old_groups[0].workers);
7264 			kfree(old_groups);
7265 		}
7266 		mddev_resume(mddev);
7267 	}
7268 	mddev_unlock(mddev);
7269 
7270 	return err ?: len;
7271 }
7272 
7273 static struct md_sysfs_entry
7274 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
7275 				raid5_show_group_thread_cnt,
7276 				raid5_store_group_thread_cnt);
7277 
7278 static struct attribute *raid5_attrs[] =  {
7279 	&raid5_stripecache_size.attr,
7280 	&raid5_stripecache_active.attr,
7281 	&raid5_preread_bypass_threshold.attr,
7282 	&raid5_group_thread_cnt.attr,
7283 	&raid5_skip_copy.attr,
7284 	&raid5_rmw_level.attr,
7285 	&raid5_stripe_size.attr,
7286 	&r5c_journal_mode.attr,
7287 	&ppl_write_hint.attr,
7288 	NULL,
7289 };
7290 static const struct attribute_group raid5_attrs_group = {
7291 	.name = NULL,
7292 	.attrs = raid5_attrs,
7293 };
7294 
7295 static int alloc_thread_groups(struct r5conf *conf, int cnt, int *group_cnt,
7296 			       struct r5worker_group **worker_groups)
7297 {
7298 	int i, j, k;
7299 	ssize_t size;
7300 	struct r5worker *workers;
7301 
7302 	if (cnt == 0) {
7303 		*group_cnt = 0;
7304 		*worker_groups = NULL;
7305 		return 0;
7306 	}
7307 	*group_cnt = num_possible_nodes();
7308 	size = sizeof(struct r5worker) * cnt;
7309 	workers = kcalloc(size, *group_cnt, GFP_NOIO);
7310 	*worker_groups = kcalloc(*group_cnt, sizeof(struct r5worker_group),
7311 				 GFP_NOIO);
7312 	if (!*worker_groups || !workers) {
7313 		kfree(workers);
7314 		kfree(*worker_groups);
7315 		return -ENOMEM;
7316 	}
7317 
7318 	for (i = 0; i < *group_cnt; i++) {
7319 		struct r5worker_group *group;
7320 
7321 		group = &(*worker_groups)[i];
7322 		INIT_LIST_HEAD(&group->handle_list);
7323 		INIT_LIST_HEAD(&group->loprio_list);
7324 		group->conf = conf;
7325 		group->workers = workers + i * cnt;
7326 
7327 		for (j = 0; j < cnt; j++) {
7328 			struct r5worker *worker = group->workers + j;
7329 			worker->group = group;
7330 			INIT_WORK(&worker->work, raid5_do_work);
7331 
7332 			for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
7333 				INIT_LIST_HEAD(worker->temp_inactive_list + k);
7334 		}
7335 	}
7336 
7337 	return 0;
7338 }
7339 
7340 static void free_thread_groups(struct r5conf *conf)
7341 {
7342 	if (conf->worker_groups)
7343 		kfree(conf->worker_groups[0].workers);
7344 	kfree(conf->worker_groups);
7345 	conf->worker_groups = NULL;
7346 }
7347 
7348 static sector_t
7349 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
7350 {
7351 	struct r5conf *conf = mddev->private;
7352 
7353 	if (!sectors)
7354 		sectors = mddev->dev_sectors;
7355 	if (!raid_disks)
7356 		/* size is defined by the smallest of previous and new size */
7357 		raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
7358 
7359 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
7360 	sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
7361 	return sectors * (raid_disks - conf->max_degraded);
7362 }
7363 
7364 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
7365 {
7366 	safe_put_page(percpu->spare_page);
7367 	percpu->spare_page = NULL;
7368 	kvfree(percpu->scribble);
7369 	percpu->scribble = NULL;
7370 }
7371 
7372 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
7373 {
7374 	if (conf->level == 6 && !percpu->spare_page) {
7375 		percpu->spare_page = alloc_page(GFP_KERNEL);
7376 		if (!percpu->spare_page)
7377 			return -ENOMEM;
7378 	}
7379 
7380 	if (scribble_alloc(percpu,
7381 			   max(conf->raid_disks,
7382 			       conf->previous_raid_disks),
7383 			   max(conf->chunk_sectors,
7384 			       conf->prev_chunk_sectors)
7385 			   / RAID5_STRIPE_SECTORS(conf))) {
7386 		free_scratch_buffer(conf, percpu);
7387 		return -ENOMEM;
7388 	}
7389 
7390 	local_lock_init(&percpu->lock);
7391 	return 0;
7392 }
7393 
7394 static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
7395 {
7396 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
7397 
7398 	free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
7399 	return 0;
7400 }
7401 
7402 static void raid5_free_percpu(struct r5conf *conf)
7403 {
7404 	if (!conf->percpu)
7405 		return;
7406 
7407 	cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
7408 	free_percpu(conf->percpu);
7409 }
7410 
7411 static void free_conf(struct r5conf *conf)
7412 {
7413 	int i;
7414 
7415 	log_exit(conf);
7416 
7417 	unregister_shrinker(&conf->shrinker);
7418 	free_thread_groups(conf);
7419 	shrink_stripes(conf);
7420 	raid5_free_percpu(conf);
7421 	for (i = 0; i < conf->pool_size; i++)
7422 		if (conf->disks[i].extra_page)
7423 			put_page(conf->disks[i].extra_page);
7424 	kfree(conf->disks);
7425 	bioset_exit(&conf->bio_split);
7426 	kfree(conf->stripe_hashtbl);
7427 	kfree(conf->pending_data);
7428 	kfree(conf);
7429 }
7430 
7431 static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
7432 {
7433 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
7434 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
7435 
7436 	if (alloc_scratch_buffer(conf, percpu)) {
7437 		pr_warn("%s: failed memory allocation for cpu%u\n",
7438 			__func__, cpu);
7439 		return -ENOMEM;
7440 	}
7441 	return 0;
7442 }
7443 
7444 static int raid5_alloc_percpu(struct r5conf *conf)
7445 {
7446 	int err = 0;
7447 
7448 	conf->percpu = alloc_percpu(struct raid5_percpu);
7449 	if (!conf->percpu)
7450 		return -ENOMEM;
7451 
7452 	err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
7453 	if (!err) {
7454 		conf->scribble_disks = max(conf->raid_disks,
7455 			conf->previous_raid_disks);
7456 		conf->scribble_sectors = max(conf->chunk_sectors,
7457 			conf->prev_chunk_sectors);
7458 	}
7459 	return err;
7460 }
7461 
7462 static unsigned long raid5_cache_scan(struct shrinker *shrink,
7463 				      struct shrink_control *sc)
7464 {
7465 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
7466 	unsigned long ret = SHRINK_STOP;
7467 
7468 	if (mutex_trylock(&conf->cache_size_mutex)) {
7469 		ret= 0;
7470 		while (ret < sc->nr_to_scan &&
7471 		       conf->max_nr_stripes > conf->min_nr_stripes) {
7472 			if (drop_one_stripe(conf) == 0) {
7473 				ret = SHRINK_STOP;
7474 				break;
7475 			}
7476 			ret++;
7477 		}
7478 		mutex_unlock(&conf->cache_size_mutex);
7479 	}
7480 	return ret;
7481 }
7482 
7483 static unsigned long raid5_cache_count(struct shrinker *shrink,
7484 				       struct shrink_control *sc)
7485 {
7486 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
7487 
7488 	if (conf->max_nr_stripes < conf->min_nr_stripes)
7489 		/* unlikely, but not impossible */
7490 		return 0;
7491 	return conf->max_nr_stripes - conf->min_nr_stripes;
7492 }
7493 
7494 static struct r5conf *setup_conf(struct mddev *mddev)
7495 {
7496 	struct r5conf *conf;
7497 	int raid_disk, memory, max_disks;
7498 	struct md_rdev *rdev;
7499 	struct disk_info *disk;
7500 	char pers_name[6];
7501 	int i;
7502 	int group_cnt;
7503 	struct r5worker_group *new_group;
7504 	int ret = -ENOMEM;
7505 
7506 	if (mddev->new_level != 5
7507 	    && mddev->new_level != 4
7508 	    && mddev->new_level != 6) {
7509 		pr_warn("md/raid:%s: raid level not set to 4/5/6 (%d)\n",
7510 			mdname(mddev), mddev->new_level);
7511 		return ERR_PTR(-EIO);
7512 	}
7513 	if ((mddev->new_level == 5
7514 	     && !algorithm_valid_raid5(mddev->new_layout)) ||
7515 	    (mddev->new_level == 6
7516 	     && !algorithm_valid_raid6(mddev->new_layout))) {
7517 		pr_warn("md/raid:%s: layout %d not supported\n",
7518 			mdname(mddev), mddev->new_layout);
7519 		return ERR_PTR(-EIO);
7520 	}
7521 	if (mddev->new_level == 6 && mddev->raid_disks < 4) {
7522 		pr_warn("md/raid:%s: not enough configured devices (%d, minimum 4)\n",
7523 			mdname(mddev), mddev->raid_disks);
7524 		return ERR_PTR(-EINVAL);
7525 	}
7526 
7527 	if (!mddev->new_chunk_sectors ||
7528 	    (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
7529 	    !is_power_of_2(mddev->new_chunk_sectors)) {
7530 		pr_warn("md/raid:%s: invalid chunk size %d\n",
7531 			mdname(mddev), mddev->new_chunk_sectors << 9);
7532 		return ERR_PTR(-EINVAL);
7533 	}
7534 
7535 	conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
7536 	if (conf == NULL)
7537 		goto abort;
7538 
7539 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
7540 	conf->stripe_size = DEFAULT_STRIPE_SIZE;
7541 	conf->stripe_shift = ilog2(DEFAULT_STRIPE_SIZE) - 9;
7542 	conf->stripe_sectors = DEFAULT_STRIPE_SIZE >> 9;
7543 #endif
7544 	INIT_LIST_HEAD(&conf->free_list);
7545 	INIT_LIST_HEAD(&conf->pending_list);
7546 	conf->pending_data = kcalloc(PENDING_IO_MAX,
7547 				     sizeof(struct r5pending_data),
7548 				     GFP_KERNEL);
7549 	if (!conf->pending_data)
7550 		goto abort;
7551 	for (i = 0; i < PENDING_IO_MAX; i++)
7552 		list_add(&conf->pending_data[i].sibling, &conf->free_list);
7553 	/* Don't enable multi-threading by default*/
7554 	if (!alloc_thread_groups(conf, 0, &group_cnt, &new_group)) {
7555 		conf->group_cnt = group_cnt;
7556 		conf->worker_cnt_per_group = 0;
7557 		conf->worker_groups = new_group;
7558 	} else
7559 		goto abort;
7560 	spin_lock_init(&conf->device_lock);
7561 	seqcount_spinlock_init(&conf->gen_lock, &conf->device_lock);
7562 	mutex_init(&conf->cache_size_mutex);
7563 
7564 	init_waitqueue_head(&conf->wait_for_quiescent);
7565 	init_waitqueue_head(&conf->wait_for_stripe);
7566 	init_waitqueue_head(&conf->wait_for_overlap);
7567 	INIT_LIST_HEAD(&conf->handle_list);
7568 	INIT_LIST_HEAD(&conf->loprio_list);
7569 	INIT_LIST_HEAD(&conf->hold_list);
7570 	INIT_LIST_HEAD(&conf->delayed_list);
7571 	INIT_LIST_HEAD(&conf->bitmap_list);
7572 	init_llist_head(&conf->released_stripes);
7573 	atomic_set(&conf->active_stripes, 0);
7574 	atomic_set(&conf->preread_active_stripes, 0);
7575 	atomic_set(&conf->active_aligned_reads, 0);
7576 	spin_lock_init(&conf->pending_bios_lock);
7577 	conf->batch_bio_dispatch = true;
7578 	rdev_for_each(rdev, mddev) {
7579 		if (test_bit(Journal, &rdev->flags))
7580 			continue;
7581 		if (bdev_nonrot(rdev->bdev)) {
7582 			conf->batch_bio_dispatch = false;
7583 			break;
7584 		}
7585 	}
7586 
7587 	conf->bypass_threshold = BYPASS_THRESHOLD;
7588 	conf->recovery_disabled = mddev->recovery_disabled - 1;
7589 
7590 	conf->raid_disks = mddev->raid_disks;
7591 	if (mddev->reshape_position == MaxSector)
7592 		conf->previous_raid_disks = mddev->raid_disks;
7593 	else
7594 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
7595 	max_disks = max(conf->raid_disks, conf->previous_raid_disks);
7596 
7597 	conf->disks = kcalloc(max_disks, sizeof(struct disk_info),
7598 			      GFP_KERNEL);
7599 
7600 	if (!conf->disks)
7601 		goto abort;
7602 
7603 	for (i = 0; i < max_disks; i++) {
7604 		conf->disks[i].extra_page = alloc_page(GFP_KERNEL);
7605 		if (!conf->disks[i].extra_page)
7606 			goto abort;
7607 	}
7608 
7609 	ret = bioset_init(&conf->bio_split, BIO_POOL_SIZE, 0, 0);
7610 	if (ret)
7611 		goto abort;
7612 	conf->mddev = mddev;
7613 
7614 	ret = -ENOMEM;
7615 	conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL);
7616 	if (!conf->stripe_hashtbl)
7617 		goto abort;
7618 
7619 	/* We init hash_locks[0] separately to that it can be used
7620 	 * as the reference lock in the spin_lock_nest_lock() call
7621 	 * in lock_all_device_hash_locks_irq in order to convince
7622 	 * lockdep that we know what we are doing.
7623 	 */
7624 	spin_lock_init(conf->hash_locks);
7625 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
7626 		spin_lock_init(conf->hash_locks + i);
7627 
7628 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
7629 		INIT_LIST_HEAD(conf->inactive_list + i);
7630 
7631 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
7632 		INIT_LIST_HEAD(conf->temp_inactive_list + i);
7633 
7634 	atomic_set(&conf->r5c_cached_full_stripes, 0);
7635 	INIT_LIST_HEAD(&conf->r5c_full_stripe_list);
7636 	atomic_set(&conf->r5c_cached_partial_stripes, 0);
7637 	INIT_LIST_HEAD(&conf->r5c_partial_stripe_list);
7638 	atomic_set(&conf->r5c_flushing_full_stripes, 0);
7639 	atomic_set(&conf->r5c_flushing_partial_stripes, 0);
7640 
7641 	conf->level = mddev->new_level;
7642 	conf->chunk_sectors = mddev->new_chunk_sectors;
7643 	ret = raid5_alloc_percpu(conf);
7644 	if (ret)
7645 		goto abort;
7646 
7647 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
7648 
7649 	ret = -EIO;
7650 	rdev_for_each(rdev, mddev) {
7651 		raid_disk = rdev->raid_disk;
7652 		if (raid_disk >= max_disks
7653 		    || raid_disk < 0 || test_bit(Journal, &rdev->flags))
7654 			continue;
7655 		disk = conf->disks + raid_disk;
7656 
7657 		if (test_bit(Replacement, &rdev->flags)) {
7658 			if (disk->replacement)
7659 				goto abort;
7660 			RCU_INIT_POINTER(disk->replacement, rdev);
7661 		} else {
7662 			if (disk->rdev)
7663 				goto abort;
7664 			RCU_INIT_POINTER(disk->rdev, rdev);
7665 		}
7666 
7667 		if (test_bit(In_sync, &rdev->flags)) {
7668 			pr_info("md/raid:%s: device %pg operational as raid disk %d\n",
7669 				mdname(mddev), rdev->bdev, raid_disk);
7670 		} else if (rdev->saved_raid_disk != raid_disk)
7671 			/* Cannot rely on bitmap to complete recovery */
7672 			conf->fullsync = 1;
7673 	}
7674 
7675 	conf->level = mddev->new_level;
7676 	if (conf->level == 6) {
7677 		conf->max_degraded = 2;
7678 		if (raid6_call.xor_syndrome)
7679 			conf->rmw_level = PARITY_ENABLE_RMW;
7680 		else
7681 			conf->rmw_level = PARITY_DISABLE_RMW;
7682 	} else {
7683 		conf->max_degraded = 1;
7684 		conf->rmw_level = PARITY_ENABLE_RMW;
7685 	}
7686 	conf->algorithm = mddev->new_layout;
7687 	conf->reshape_progress = mddev->reshape_position;
7688 	if (conf->reshape_progress != MaxSector) {
7689 		conf->prev_chunk_sectors = mddev->chunk_sectors;
7690 		conf->prev_algo = mddev->layout;
7691 	} else {
7692 		conf->prev_chunk_sectors = conf->chunk_sectors;
7693 		conf->prev_algo = conf->algorithm;
7694 	}
7695 
7696 	conf->min_nr_stripes = NR_STRIPES;
7697 	if (mddev->reshape_position != MaxSector) {
7698 		int stripes = max_t(int,
7699 			((mddev->chunk_sectors << 9) / RAID5_STRIPE_SIZE(conf)) * 4,
7700 			((mddev->new_chunk_sectors << 9) / RAID5_STRIPE_SIZE(conf)) * 4);
7701 		conf->min_nr_stripes = max(NR_STRIPES, stripes);
7702 		if (conf->min_nr_stripes != NR_STRIPES)
7703 			pr_info("md/raid:%s: force stripe size %d for reshape\n",
7704 				mdname(mddev), conf->min_nr_stripes);
7705 	}
7706 	memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
7707 		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
7708 	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
7709 	if (grow_stripes(conf, conf->min_nr_stripes)) {
7710 		pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
7711 			mdname(mddev), memory);
7712 		ret = -ENOMEM;
7713 		goto abort;
7714 	} else
7715 		pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
7716 	/*
7717 	 * Losing a stripe head costs more than the time to refill it,
7718 	 * it reduces the queue depth and so can hurt throughput.
7719 	 * So set it rather large, scaled by number of devices.
7720 	 */
7721 	conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
7722 	conf->shrinker.scan_objects = raid5_cache_scan;
7723 	conf->shrinker.count_objects = raid5_cache_count;
7724 	conf->shrinker.batch = 128;
7725 	conf->shrinker.flags = 0;
7726 	ret = register_shrinker(&conf->shrinker, "md-raid5:%s", mdname(mddev));
7727 	if (ret) {
7728 		pr_warn("md/raid:%s: couldn't register shrinker.\n",
7729 			mdname(mddev));
7730 		goto abort;
7731 	}
7732 
7733 	sprintf(pers_name, "raid%d", mddev->new_level);
7734 	rcu_assign_pointer(conf->thread,
7735 			   md_register_thread(raid5d, mddev, pers_name));
7736 	if (!conf->thread) {
7737 		pr_warn("md/raid:%s: couldn't allocate thread.\n",
7738 			mdname(mddev));
7739 		ret = -ENOMEM;
7740 		goto abort;
7741 	}
7742 
7743 	return conf;
7744 
7745  abort:
7746 	if (conf)
7747 		free_conf(conf);
7748 	return ERR_PTR(ret);
7749 }
7750 
7751 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
7752 {
7753 	switch (algo) {
7754 	case ALGORITHM_PARITY_0:
7755 		if (raid_disk < max_degraded)
7756 			return 1;
7757 		break;
7758 	case ALGORITHM_PARITY_N:
7759 		if (raid_disk >= raid_disks - max_degraded)
7760 			return 1;
7761 		break;
7762 	case ALGORITHM_PARITY_0_6:
7763 		if (raid_disk == 0 ||
7764 		    raid_disk == raid_disks - 1)
7765 			return 1;
7766 		break;
7767 	case ALGORITHM_LEFT_ASYMMETRIC_6:
7768 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
7769 	case ALGORITHM_LEFT_SYMMETRIC_6:
7770 	case ALGORITHM_RIGHT_SYMMETRIC_6:
7771 		if (raid_disk == raid_disks - 1)
7772 			return 1;
7773 	}
7774 	return 0;
7775 }
7776 
7777 static void raid5_set_io_opt(struct r5conf *conf)
7778 {
7779 	blk_queue_io_opt(conf->mddev->queue, (conf->chunk_sectors << 9) *
7780 			 (conf->raid_disks - conf->max_degraded));
7781 }
7782 
7783 static int raid5_run(struct mddev *mddev)
7784 {
7785 	struct r5conf *conf;
7786 	int dirty_parity_disks = 0;
7787 	struct md_rdev *rdev;
7788 	struct md_rdev *journal_dev = NULL;
7789 	sector_t reshape_offset = 0;
7790 	int i, ret = 0;
7791 	long long min_offset_diff = 0;
7792 	int first = 1;
7793 
7794 	if (acct_bioset_init(mddev)) {
7795 		pr_err("md/raid456:%s: alloc acct bioset failed.\n", mdname(mddev));
7796 		return -ENOMEM;
7797 	}
7798 
7799 	if (mddev_init_writes_pending(mddev) < 0) {
7800 		ret = -ENOMEM;
7801 		goto exit_acct_set;
7802 	}
7803 
7804 	if (mddev->recovery_cp != MaxSector)
7805 		pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
7806 			  mdname(mddev));
7807 
7808 	rdev_for_each(rdev, mddev) {
7809 		long long diff;
7810 
7811 		if (test_bit(Journal, &rdev->flags)) {
7812 			journal_dev = rdev;
7813 			continue;
7814 		}
7815 		if (rdev->raid_disk < 0)
7816 			continue;
7817 		diff = (rdev->new_data_offset - rdev->data_offset);
7818 		if (first) {
7819 			min_offset_diff = diff;
7820 			first = 0;
7821 		} else if (mddev->reshape_backwards &&
7822 			 diff < min_offset_diff)
7823 			min_offset_diff = diff;
7824 		else if (!mddev->reshape_backwards &&
7825 			 diff > min_offset_diff)
7826 			min_offset_diff = diff;
7827 	}
7828 
7829 	if ((test_bit(MD_HAS_JOURNAL, &mddev->flags) || journal_dev) &&
7830 	    (mddev->bitmap_info.offset || mddev->bitmap_info.file)) {
7831 		pr_notice("md/raid:%s: array cannot have both journal and bitmap\n",
7832 			  mdname(mddev));
7833 		ret = -EINVAL;
7834 		goto exit_acct_set;
7835 	}
7836 
7837 	if (mddev->reshape_position != MaxSector) {
7838 		/* Check that we can continue the reshape.
7839 		 * Difficulties arise if the stripe we would write to
7840 		 * next is at or after the stripe we would read from next.
7841 		 * For a reshape that changes the number of devices, this
7842 		 * is only possible for a very short time, and mdadm makes
7843 		 * sure that time appears to have past before assembling
7844 		 * the array.  So we fail if that time hasn't passed.
7845 		 * For a reshape that keeps the number of devices the same
7846 		 * mdadm must be monitoring the reshape can keeping the
7847 		 * critical areas read-only and backed up.  It will start
7848 		 * the array in read-only mode, so we check for that.
7849 		 */
7850 		sector_t here_new, here_old;
7851 		int old_disks;
7852 		int max_degraded = (mddev->level == 6 ? 2 : 1);
7853 		int chunk_sectors;
7854 		int new_data_disks;
7855 
7856 		if (journal_dev) {
7857 			pr_warn("md/raid:%s: don't support reshape with journal - aborting.\n",
7858 				mdname(mddev));
7859 			ret = -EINVAL;
7860 			goto exit_acct_set;
7861 		}
7862 
7863 		if (mddev->new_level != mddev->level) {
7864 			pr_warn("md/raid:%s: unsupported reshape required - aborting.\n",
7865 				mdname(mddev));
7866 			ret = -EINVAL;
7867 			goto exit_acct_set;
7868 		}
7869 		old_disks = mddev->raid_disks - mddev->delta_disks;
7870 		/* reshape_position must be on a new-stripe boundary, and one
7871 		 * further up in new geometry must map after here in old
7872 		 * geometry.
7873 		 * If the chunk sizes are different, then as we perform reshape
7874 		 * in units of the largest of the two, reshape_position needs
7875 		 * be a multiple of the largest chunk size times new data disks.
7876 		 */
7877 		here_new = mddev->reshape_position;
7878 		chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
7879 		new_data_disks = mddev->raid_disks - max_degraded;
7880 		if (sector_div(here_new, chunk_sectors * new_data_disks)) {
7881 			pr_warn("md/raid:%s: reshape_position not on a stripe boundary\n",
7882 				mdname(mddev));
7883 			ret = -EINVAL;
7884 			goto exit_acct_set;
7885 		}
7886 		reshape_offset = here_new * chunk_sectors;
7887 		/* here_new is the stripe we will write to */
7888 		here_old = mddev->reshape_position;
7889 		sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
7890 		/* here_old is the first stripe that we might need to read
7891 		 * from */
7892 		if (mddev->delta_disks == 0) {
7893 			/* We cannot be sure it is safe to start an in-place
7894 			 * reshape.  It is only safe if user-space is monitoring
7895 			 * and taking constant backups.
7896 			 * mdadm always starts a situation like this in
7897 			 * readonly mode so it can take control before
7898 			 * allowing any writes.  So just check for that.
7899 			 */
7900 			if (abs(min_offset_diff) >= mddev->chunk_sectors &&
7901 			    abs(min_offset_diff) >= mddev->new_chunk_sectors)
7902 				/* not really in-place - so OK */;
7903 			else if (mddev->ro == 0) {
7904 				pr_warn("md/raid:%s: in-place reshape must be started in read-only mode - aborting\n",
7905 					mdname(mddev));
7906 				ret = -EINVAL;
7907 				goto exit_acct_set;
7908 			}
7909 		} else if (mddev->reshape_backwards
7910 		    ? (here_new * chunk_sectors + min_offset_diff <=
7911 		       here_old * chunk_sectors)
7912 		    : (here_new * chunk_sectors >=
7913 		       here_old * chunk_sectors + (-min_offset_diff))) {
7914 			/* Reading from the same stripe as writing to - bad */
7915 			pr_warn("md/raid:%s: reshape_position too early for auto-recovery - aborting.\n",
7916 				mdname(mddev));
7917 			ret = -EINVAL;
7918 			goto exit_acct_set;
7919 		}
7920 		pr_debug("md/raid:%s: reshape will continue\n", mdname(mddev));
7921 		/* OK, we should be able to continue; */
7922 	} else {
7923 		BUG_ON(mddev->level != mddev->new_level);
7924 		BUG_ON(mddev->layout != mddev->new_layout);
7925 		BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
7926 		BUG_ON(mddev->delta_disks != 0);
7927 	}
7928 
7929 	if (test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
7930 	    test_bit(MD_HAS_PPL, &mddev->flags)) {
7931 		pr_warn("md/raid:%s: using journal device and PPL not allowed - disabling PPL\n",
7932 			mdname(mddev));
7933 		clear_bit(MD_HAS_PPL, &mddev->flags);
7934 		clear_bit(MD_HAS_MULTIPLE_PPLS, &mddev->flags);
7935 	}
7936 
7937 	if (mddev->private == NULL)
7938 		conf = setup_conf(mddev);
7939 	else
7940 		conf = mddev->private;
7941 
7942 	if (IS_ERR(conf)) {
7943 		ret = PTR_ERR(conf);
7944 		goto exit_acct_set;
7945 	}
7946 
7947 	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
7948 		if (!journal_dev) {
7949 			pr_warn("md/raid:%s: journal disk is missing, force array readonly\n",
7950 				mdname(mddev));
7951 			mddev->ro = 1;
7952 			set_disk_ro(mddev->gendisk, 1);
7953 		} else if (mddev->recovery_cp == MaxSector)
7954 			set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
7955 	}
7956 
7957 	conf->min_offset_diff = min_offset_diff;
7958 	rcu_assign_pointer(mddev->thread, conf->thread);
7959 	rcu_assign_pointer(conf->thread, NULL);
7960 	mddev->private = conf;
7961 
7962 	for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
7963 	     i++) {
7964 		rdev = rdev_mdlock_deref(mddev, conf->disks[i].rdev);
7965 		if (!rdev && conf->disks[i].replacement) {
7966 			/* The replacement is all we have yet */
7967 			rdev = rdev_mdlock_deref(mddev,
7968 						 conf->disks[i].replacement);
7969 			conf->disks[i].replacement = NULL;
7970 			clear_bit(Replacement, &rdev->flags);
7971 			rcu_assign_pointer(conf->disks[i].rdev, rdev);
7972 		}
7973 		if (!rdev)
7974 			continue;
7975 		if (rcu_access_pointer(conf->disks[i].replacement) &&
7976 		    conf->reshape_progress != MaxSector) {
7977 			/* replacements and reshape simply do not mix. */
7978 			pr_warn("md: cannot handle concurrent replacement and reshape.\n");
7979 			goto abort;
7980 		}
7981 		if (test_bit(In_sync, &rdev->flags))
7982 			continue;
7983 		/* This disc is not fully in-sync.  However if it
7984 		 * just stored parity (beyond the recovery_offset),
7985 		 * when we don't need to be concerned about the
7986 		 * array being dirty.
7987 		 * When reshape goes 'backwards', we never have
7988 		 * partially completed devices, so we only need
7989 		 * to worry about reshape going forwards.
7990 		 */
7991 		/* Hack because v0.91 doesn't store recovery_offset properly. */
7992 		if (mddev->major_version == 0 &&
7993 		    mddev->minor_version > 90)
7994 			rdev->recovery_offset = reshape_offset;
7995 
7996 		if (rdev->recovery_offset < reshape_offset) {
7997 			/* We need to check old and new layout */
7998 			if (!only_parity(rdev->raid_disk,
7999 					 conf->algorithm,
8000 					 conf->raid_disks,
8001 					 conf->max_degraded))
8002 				continue;
8003 		}
8004 		if (!only_parity(rdev->raid_disk,
8005 				 conf->prev_algo,
8006 				 conf->previous_raid_disks,
8007 				 conf->max_degraded))
8008 			continue;
8009 		dirty_parity_disks++;
8010 	}
8011 
8012 	/*
8013 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
8014 	 */
8015 	mddev->degraded = raid5_calc_degraded(conf);
8016 
8017 	if (has_failed(conf)) {
8018 		pr_crit("md/raid:%s: not enough operational devices (%d/%d failed)\n",
8019 			mdname(mddev), mddev->degraded, conf->raid_disks);
8020 		goto abort;
8021 	}
8022 
8023 	/* device size must be a multiple of chunk size */
8024 	mddev->dev_sectors &= ~((sector_t)mddev->chunk_sectors - 1);
8025 	mddev->resync_max_sectors = mddev->dev_sectors;
8026 
8027 	if (mddev->degraded > dirty_parity_disks &&
8028 	    mddev->recovery_cp != MaxSector) {
8029 		if (test_bit(MD_HAS_PPL, &mddev->flags))
8030 			pr_crit("md/raid:%s: starting dirty degraded array with PPL.\n",
8031 				mdname(mddev));
8032 		else if (mddev->ok_start_degraded)
8033 			pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
8034 				mdname(mddev));
8035 		else {
8036 			pr_crit("md/raid:%s: cannot start dirty degraded array.\n",
8037 				mdname(mddev));
8038 			goto abort;
8039 		}
8040 	}
8041 
8042 	pr_info("md/raid:%s: raid level %d active with %d out of %d devices, algorithm %d\n",
8043 		mdname(mddev), conf->level,
8044 		mddev->raid_disks-mddev->degraded, mddev->raid_disks,
8045 		mddev->new_layout);
8046 
8047 	print_raid5_conf(conf);
8048 
8049 	if (conf->reshape_progress != MaxSector) {
8050 		conf->reshape_safe = conf->reshape_progress;
8051 		atomic_set(&conf->reshape_stripes, 0);
8052 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
8053 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
8054 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
8055 		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
8056 		rcu_assign_pointer(mddev->sync_thread,
8057 			md_register_thread(md_do_sync, mddev, "reshape"));
8058 		if (!mddev->sync_thread)
8059 			goto abort;
8060 	}
8061 
8062 	/* Ok, everything is just fine now */
8063 	if (mddev->to_remove == &raid5_attrs_group)
8064 		mddev->to_remove = NULL;
8065 	else if (mddev->kobj.sd &&
8066 	    sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
8067 		pr_warn("raid5: failed to create sysfs attributes for %s\n",
8068 			mdname(mddev));
8069 	md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
8070 
8071 	if (mddev->queue) {
8072 		int chunk_size;
8073 		/* read-ahead size must cover two whole stripes, which
8074 		 * is 2 * (datadisks) * chunksize where 'n' is the
8075 		 * number of raid devices
8076 		 */
8077 		int data_disks = conf->previous_raid_disks - conf->max_degraded;
8078 		int stripe = data_disks *
8079 			((mddev->chunk_sectors << 9) / PAGE_SIZE);
8080 
8081 		chunk_size = mddev->chunk_sectors << 9;
8082 		blk_queue_io_min(mddev->queue, chunk_size);
8083 		raid5_set_io_opt(conf);
8084 		mddev->queue->limits.raid_partial_stripes_expensive = 1;
8085 		/*
8086 		 * We can only discard a whole stripe. It doesn't make sense to
8087 		 * discard data disk but write parity disk
8088 		 */
8089 		stripe = stripe * PAGE_SIZE;
8090 		stripe = roundup_pow_of_two(stripe);
8091 		mddev->queue->limits.discard_granularity = stripe;
8092 
8093 		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
8094 
8095 		rdev_for_each(rdev, mddev) {
8096 			disk_stack_limits(mddev->gendisk, rdev->bdev,
8097 					  rdev->data_offset << 9);
8098 			disk_stack_limits(mddev->gendisk, rdev->bdev,
8099 					  rdev->new_data_offset << 9);
8100 		}
8101 
8102 		/*
8103 		 * zeroing is required, otherwise data
8104 		 * could be lost. Consider a scenario: discard a stripe
8105 		 * (the stripe could be inconsistent if
8106 		 * discard_zeroes_data is 0); write one disk of the
8107 		 * stripe (the stripe could be inconsistent again
8108 		 * depending on which disks are used to calculate
8109 		 * parity); the disk is broken; The stripe data of this
8110 		 * disk is lost.
8111 		 *
8112 		 * We only allow DISCARD if the sysadmin has confirmed that
8113 		 * only safe devices are in use by setting a module parameter.
8114 		 * A better idea might be to turn DISCARD into WRITE_ZEROES
8115 		 * requests, as that is required to be safe.
8116 		 */
8117 		if (!devices_handle_discard_safely ||
8118 		    mddev->queue->limits.max_discard_sectors < (stripe >> 9) ||
8119 		    mddev->queue->limits.discard_granularity < stripe)
8120 			blk_queue_max_discard_sectors(mddev->queue, 0);
8121 
8122 		/*
8123 		 * Requests require having a bitmap for each stripe.
8124 		 * Limit the max sectors based on this.
8125 		 */
8126 		blk_queue_max_hw_sectors(mddev->queue,
8127 			RAID5_MAX_REQ_STRIPES << RAID5_STRIPE_SHIFT(conf));
8128 
8129 		/* No restrictions on the number of segments in the request */
8130 		blk_queue_max_segments(mddev->queue, USHRT_MAX);
8131 	}
8132 
8133 	if (log_init(conf, journal_dev, raid5_has_ppl(conf)))
8134 		goto abort;
8135 
8136 	return 0;
8137 abort:
8138 	md_unregister_thread(&mddev->thread);
8139 	print_raid5_conf(conf);
8140 	free_conf(conf);
8141 	mddev->private = NULL;
8142 	pr_warn("md/raid:%s: failed to run raid set.\n", mdname(mddev));
8143 	ret = -EIO;
8144 exit_acct_set:
8145 	acct_bioset_exit(mddev);
8146 	return ret;
8147 }
8148 
8149 static void raid5_free(struct mddev *mddev, void *priv)
8150 {
8151 	struct r5conf *conf = priv;
8152 
8153 	free_conf(conf);
8154 	acct_bioset_exit(mddev);
8155 	mddev->to_remove = &raid5_attrs_group;
8156 }
8157 
8158 static void raid5_status(struct seq_file *seq, struct mddev *mddev)
8159 {
8160 	struct r5conf *conf = mddev->private;
8161 	int i;
8162 
8163 	seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
8164 		conf->chunk_sectors / 2, mddev->layout);
8165 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
8166 	rcu_read_lock();
8167 	for (i = 0; i < conf->raid_disks; i++) {
8168 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
8169 		seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
8170 	}
8171 	rcu_read_unlock();
8172 	seq_printf (seq, "]");
8173 }
8174 
8175 static void print_raid5_conf (struct r5conf *conf)
8176 {
8177 	struct md_rdev *rdev;
8178 	int i;
8179 
8180 	pr_debug("RAID conf printout:\n");
8181 	if (!conf) {
8182 		pr_debug("(conf==NULL)\n");
8183 		return;
8184 	}
8185 	pr_debug(" --- level:%d rd:%d wd:%d\n", conf->level,
8186 	       conf->raid_disks,
8187 	       conf->raid_disks - conf->mddev->degraded);
8188 
8189 	rcu_read_lock();
8190 	for (i = 0; i < conf->raid_disks; i++) {
8191 		rdev = rcu_dereference(conf->disks[i].rdev);
8192 		if (rdev)
8193 			pr_debug(" disk %d, o:%d, dev:%pg\n",
8194 			       i, !test_bit(Faulty, &rdev->flags),
8195 			       rdev->bdev);
8196 	}
8197 	rcu_read_unlock();
8198 }
8199 
8200 static int raid5_spare_active(struct mddev *mddev)
8201 {
8202 	int i;
8203 	struct r5conf *conf = mddev->private;
8204 	struct md_rdev *rdev, *replacement;
8205 	int count = 0;
8206 	unsigned long flags;
8207 
8208 	for (i = 0; i < conf->raid_disks; i++) {
8209 		rdev = rdev_mdlock_deref(mddev, conf->disks[i].rdev);
8210 		replacement = rdev_mdlock_deref(mddev,
8211 						conf->disks[i].replacement);
8212 		if (replacement
8213 		    && replacement->recovery_offset == MaxSector
8214 		    && !test_bit(Faulty, &replacement->flags)
8215 		    && !test_and_set_bit(In_sync, &replacement->flags)) {
8216 			/* Replacement has just become active. */
8217 			if (!rdev
8218 			    || !test_and_clear_bit(In_sync, &rdev->flags))
8219 				count++;
8220 			if (rdev) {
8221 				/* Replaced device not technically faulty,
8222 				 * but we need to be sure it gets removed
8223 				 * and never re-added.
8224 				 */
8225 				set_bit(Faulty, &rdev->flags);
8226 				sysfs_notify_dirent_safe(
8227 					rdev->sysfs_state);
8228 			}
8229 			sysfs_notify_dirent_safe(replacement->sysfs_state);
8230 		} else if (rdev
8231 		    && rdev->recovery_offset == MaxSector
8232 		    && !test_bit(Faulty, &rdev->flags)
8233 		    && !test_and_set_bit(In_sync, &rdev->flags)) {
8234 			count++;
8235 			sysfs_notify_dirent_safe(rdev->sysfs_state);
8236 		}
8237 	}
8238 	spin_lock_irqsave(&conf->device_lock, flags);
8239 	mddev->degraded = raid5_calc_degraded(conf);
8240 	spin_unlock_irqrestore(&conf->device_lock, flags);
8241 	print_raid5_conf(conf);
8242 	return count;
8243 }
8244 
8245 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
8246 {
8247 	struct r5conf *conf = mddev->private;
8248 	int err = 0;
8249 	int number = rdev->raid_disk;
8250 	struct md_rdev __rcu **rdevp;
8251 	struct disk_info *p;
8252 	struct md_rdev *tmp;
8253 
8254 	print_raid5_conf(conf);
8255 	if (test_bit(Journal, &rdev->flags) && conf->log) {
8256 		/*
8257 		 * we can't wait pending write here, as this is called in
8258 		 * raid5d, wait will deadlock.
8259 		 * neilb: there is no locking about new writes here,
8260 		 * so this cannot be safe.
8261 		 */
8262 		if (atomic_read(&conf->active_stripes) ||
8263 		    atomic_read(&conf->r5c_cached_full_stripes) ||
8264 		    atomic_read(&conf->r5c_cached_partial_stripes)) {
8265 			return -EBUSY;
8266 		}
8267 		log_exit(conf);
8268 		return 0;
8269 	}
8270 	if (unlikely(number >= conf->pool_size))
8271 		return 0;
8272 	p = conf->disks + number;
8273 	if (rdev == rcu_access_pointer(p->rdev))
8274 		rdevp = &p->rdev;
8275 	else if (rdev == rcu_access_pointer(p->replacement))
8276 		rdevp = &p->replacement;
8277 	else
8278 		return 0;
8279 
8280 	if (number >= conf->raid_disks &&
8281 	    conf->reshape_progress == MaxSector)
8282 		clear_bit(In_sync, &rdev->flags);
8283 
8284 	if (test_bit(In_sync, &rdev->flags) ||
8285 	    atomic_read(&rdev->nr_pending)) {
8286 		err = -EBUSY;
8287 		goto abort;
8288 	}
8289 	/* Only remove non-faulty devices if recovery
8290 	 * isn't possible.
8291 	 */
8292 	if (!test_bit(Faulty, &rdev->flags) &&
8293 	    mddev->recovery_disabled != conf->recovery_disabled &&
8294 	    !has_failed(conf) &&
8295 	    (!rcu_access_pointer(p->replacement) ||
8296 	     rcu_access_pointer(p->replacement) == rdev) &&
8297 	    number < conf->raid_disks) {
8298 		err = -EBUSY;
8299 		goto abort;
8300 	}
8301 	*rdevp = NULL;
8302 	if (!test_bit(RemoveSynchronized, &rdev->flags)) {
8303 		lockdep_assert_held(&mddev->reconfig_mutex);
8304 		synchronize_rcu();
8305 		if (atomic_read(&rdev->nr_pending)) {
8306 			/* lost the race, try later */
8307 			err = -EBUSY;
8308 			rcu_assign_pointer(*rdevp, rdev);
8309 		}
8310 	}
8311 	if (!err) {
8312 		err = log_modify(conf, rdev, false);
8313 		if (err)
8314 			goto abort;
8315 	}
8316 
8317 	tmp = rcu_access_pointer(p->replacement);
8318 	if (tmp) {
8319 		/* We must have just cleared 'rdev' */
8320 		rcu_assign_pointer(p->rdev, tmp);
8321 		clear_bit(Replacement, &tmp->flags);
8322 		smp_mb(); /* Make sure other CPUs may see both as identical
8323 			   * but will never see neither - if they are careful
8324 			   */
8325 		rcu_assign_pointer(p->replacement, NULL);
8326 
8327 		if (!err)
8328 			err = log_modify(conf, tmp, true);
8329 	}
8330 
8331 	clear_bit(WantReplacement, &rdev->flags);
8332 abort:
8333 
8334 	print_raid5_conf(conf);
8335 	return err;
8336 }
8337 
8338 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
8339 {
8340 	struct r5conf *conf = mddev->private;
8341 	int ret, err = -EEXIST;
8342 	int disk;
8343 	struct disk_info *p;
8344 	struct md_rdev *tmp;
8345 	int first = 0;
8346 	int last = conf->raid_disks - 1;
8347 
8348 	if (test_bit(Journal, &rdev->flags)) {
8349 		if (conf->log)
8350 			return -EBUSY;
8351 
8352 		rdev->raid_disk = 0;
8353 		/*
8354 		 * The array is in readonly mode if journal is missing, so no
8355 		 * write requests running. We should be safe
8356 		 */
8357 		ret = log_init(conf, rdev, false);
8358 		if (ret)
8359 			return ret;
8360 
8361 		ret = r5l_start(conf->log);
8362 		if (ret)
8363 			return ret;
8364 
8365 		return 0;
8366 	}
8367 	if (mddev->recovery_disabled == conf->recovery_disabled)
8368 		return -EBUSY;
8369 
8370 	if (rdev->saved_raid_disk < 0 && has_failed(conf))
8371 		/* no point adding a device */
8372 		return -EINVAL;
8373 
8374 	if (rdev->raid_disk >= 0)
8375 		first = last = rdev->raid_disk;
8376 
8377 	/*
8378 	 * find the disk ... but prefer rdev->saved_raid_disk
8379 	 * if possible.
8380 	 */
8381 	if (rdev->saved_raid_disk >= first &&
8382 	    rdev->saved_raid_disk <= last &&
8383 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
8384 		first = rdev->saved_raid_disk;
8385 
8386 	for (disk = first; disk <= last; disk++) {
8387 		p = conf->disks + disk;
8388 		if (p->rdev == NULL) {
8389 			clear_bit(In_sync, &rdev->flags);
8390 			rdev->raid_disk = disk;
8391 			if (rdev->saved_raid_disk != disk)
8392 				conf->fullsync = 1;
8393 			rcu_assign_pointer(p->rdev, rdev);
8394 
8395 			err = log_modify(conf, rdev, true);
8396 
8397 			goto out;
8398 		}
8399 	}
8400 	for (disk = first; disk <= last; disk++) {
8401 		p = conf->disks + disk;
8402 		tmp = rdev_mdlock_deref(mddev, p->rdev);
8403 		if (test_bit(WantReplacement, &tmp->flags) &&
8404 		    mddev->reshape_position == MaxSector &&
8405 		    p->replacement == NULL) {
8406 			clear_bit(In_sync, &rdev->flags);
8407 			set_bit(Replacement, &rdev->flags);
8408 			rdev->raid_disk = disk;
8409 			err = 0;
8410 			conf->fullsync = 1;
8411 			rcu_assign_pointer(p->replacement, rdev);
8412 			break;
8413 		}
8414 	}
8415 out:
8416 	print_raid5_conf(conf);
8417 	return err;
8418 }
8419 
8420 static int raid5_resize(struct mddev *mddev, sector_t sectors)
8421 {
8422 	/* no resync is happening, and there is enough space
8423 	 * on all devices, so we can resize.
8424 	 * We need to make sure resync covers any new space.
8425 	 * If the array is shrinking we should possibly wait until
8426 	 * any io in the removed space completes, but it hardly seems
8427 	 * worth it.
8428 	 */
8429 	sector_t newsize;
8430 	struct r5conf *conf = mddev->private;
8431 
8432 	if (raid5_has_log(conf) || raid5_has_ppl(conf))
8433 		return -EINVAL;
8434 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
8435 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
8436 	if (mddev->external_size &&
8437 	    mddev->array_sectors > newsize)
8438 		return -EINVAL;
8439 	if (mddev->bitmap) {
8440 		int ret = md_bitmap_resize(mddev->bitmap, sectors, 0, 0);
8441 		if (ret)
8442 			return ret;
8443 	}
8444 	md_set_array_sectors(mddev, newsize);
8445 	if (sectors > mddev->dev_sectors &&
8446 	    mddev->recovery_cp > mddev->dev_sectors) {
8447 		mddev->recovery_cp = mddev->dev_sectors;
8448 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
8449 	}
8450 	mddev->dev_sectors = sectors;
8451 	mddev->resync_max_sectors = sectors;
8452 	return 0;
8453 }
8454 
8455 static int check_stripe_cache(struct mddev *mddev)
8456 {
8457 	/* Can only proceed if there are plenty of stripe_heads.
8458 	 * We need a minimum of one full stripe,, and for sensible progress
8459 	 * it is best to have about 4 times that.
8460 	 * If we require 4 times, then the default 256 4K stripe_heads will
8461 	 * allow for chunk sizes up to 256K, which is probably OK.
8462 	 * If the chunk size is greater, user-space should request more
8463 	 * stripe_heads first.
8464 	 */
8465 	struct r5conf *conf = mddev->private;
8466 	if (((mddev->chunk_sectors << 9) / RAID5_STRIPE_SIZE(conf)) * 4
8467 	    > conf->min_nr_stripes ||
8468 	    ((mddev->new_chunk_sectors << 9) / RAID5_STRIPE_SIZE(conf)) * 4
8469 	    > conf->min_nr_stripes) {
8470 		pr_warn("md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
8471 			mdname(mddev),
8472 			((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
8473 			 / RAID5_STRIPE_SIZE(conf))*4);
8474 		return 0;
8475 	}
8476 	return 1;
8477 }
8478 
8479 static int check_reshape(struct mddev *mddev)
8480 {
8481 	struct r5conf *conf = mddev->private;
8482 
8483 	if (raid5_has_log(conf) || raid5_has_ppl(conf))
8484 		return -EINVAL;
8485 	if (mddev->delta_disks == 0 &&
8486 	    mddev->new_layout == mddev->layout &&
8487 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
8488 		return 0; /* nothing to do */
8489 	if (has_failed(conf))
8490 		return -EINVAL;
8491 	if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
8492 		/* We might be able to shrink, but the devices must
8493 		 * be made bigger first.
8494 		 * For raid6, 4 is the minimum size.
8495 		 * Otherwise 2 is the minimum
8496 		 */
8497 		int min = 2;
8498 		if (mddev->level == 6)
8499 			min = 4;
8500 		if (mddev->raid_disks + mddev->delta_disks < min)
8501 			return -EINVAL;
8502 	}
8503 
8504 	if (!check_stripe_cache(mddev))
8505 		return -ENOSPC;
8506 
8507 	if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
8508 	    mddev->delta_disks > 0)
8509 		if (resize_chunks(conf,
8510 				  conf->previous_raid_disks
8511 				  + max(0, mddev->delta_disks),
8512 				  max(mddev->new_chunk_sectors,
8513 				      mddev->chunk_sectors)
8514 			    ) < 0)
8515 			return -ENOMEM;
8516 
8517 	if (conf->previous_raid_disks + mddev->delta_disks <= conf->pool_size)
8518 		return 0; /* never bother to shrink */
8519 	return resize_stripes(conf, (conf->previous_raid_disks
8520 				     + mddev->delta_disks));
8521 }
8522 
8523 static int raid5_start_reshape(struct mddev *mddev)
8524 {
8525 	struct r5conf *conf = mddev->private;
8526 	struct md_rdev *rdev;
8527 	int spares = 0;
8528 	int i;
8529 	unsigned long flags;
8530 
8531 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
8532 		return -EBUSY;
8533 
8534 	if (!check_stripe_cache(mddev))
8535 		return -ENOSPC;
8536 
8537 	if (has_failed(conf))
8538 		return -EINVAL;
8539 
8540 	/* raid5 can't handle concurrent reshape and recovery */
8541 	if (mddev->recovery_cp < MaxSector)
8542 		return -EBUSY;
8543 	for (i = 0; i < conf->raid_disks; i++)
8544 		if (rdev_mdlock_deref(mddev, conf->disks[i].replacement))
8545 			return -EBUSY;
8546 
8547 	rdev_for_each(rdev, mddev) {
8548 		if (!test_bit(In_sync, &rdev->flags)
8549 		    && !test_bit(Faulty, &rdev->flags))
8550 			spares++;
8551 	}
8552 
8553 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
8554 		/* Not enough devices even to make a degraded array
8555 		 * of that size
8556 		 */
8557 		return -EINVAL;
8558 
8559 	/* Refuse to reduce size of the array.  Any reductions in
8560 	 * array size must be through explicit setting of array_size
8561 	 * attribute.
8562 	 */
8563 	if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
8564 	    < mddev->array_sectors) {
8565 		pr_warn("md/raid:%s: array size must be reduced before number of disks\n",
8566 			mdname(mddev));
8567 		return -EINVAL;
8568 	}
8569 
8570 	atomic_set(&conf->reshape_stripes, 0);
8571 	spin_lock_irq(&conf->device_lock);
8572 	write_seqcount_begin(&conf->gen_lock);
8573 	conf->previous_raid_disks = conf->raid_disks;
8574 	conf->raid_disks += mddev->delta_disks;
8575 	conf->prev_chunk_sectors = conf->chunk_sectors;
8576 	conf->chunk_sectors = mddev->new_chunk_sectors;
8577 	conf->prev_algo = conf->algorithm;
8578 	conf->algorithm = mddev->new_layout;
8579 	conf->generation++;
8580 	/* Code that selects data_offset needs to see the generation update
8581 	 * if reshape_progress has been set - so a memory barrier needed.
8582 	 */
8583 	smp_mb();
8584 	if (mddev->reshape_backwards)
8585 		conf->reshape_progress = raid5_size(mddev, 0, 0);
8586 	else
8587 		conf->reshape_progress = 0;
8588 	conf->reshape_safe = conf->reshape_progress;
8589 	write_seqcount_end(&conf->gen_lock);
8590 	spin_unlock_irq(&conf->device_lock);
8591 
8592 	/* Now make sure any requests that proceeded on the assumption
8593 	 * the reshape wasn't running - like Discard or Read - have
8594 	 * completed.
8595 	 */
8596 	mddev_suspend(mddev);
8597 	mddev_resume(mddev);
8598 
8599 	/* Add some new drives, as many as will fit.
8600 	 * We know there are enough to make the newly sized array work.
8601 	 * Don't add devices if we are reducing the number of
8602 	 * devices in the array.  This is because it is not possible
8603 	 * to correctly record the "partially reconstructed" state of
8604 	 * such devices during the reshape and confusion could result.
8605 	 */
8606 	if (mddev->delta_disks >= 0) {
8607 		rdev_for_each(rdev, mddev)
8608 			if (rdev->raid_disk < 0 &&
8609 			    !test_bit(Faulty, &rdev->flags)) {
8610 				if (raid5_add_disk(mddev, rdev) == 0) {
8611 					if (rdev->raid_disk
8612 					    >= conf->previous_raid_disks)
8613 						set_bit(In_sync, &rdev->flags);
8614 					else
8615 						rdev->recovery_offset = 0;
8616 
8617 					/* Failure here is OK */
8618 					sysfs_link_rdev(mddev, rdev);
8619 				}
8620 			} else if (rdev->raid_disk >= conf->previous_raid_disks
8621 				   && !test_bit(Faulty, &rdev->flags)) {
8622 				/* This is a spare that was manually added */
8623 				set_bit(In_sync, &rdev->flags);
8624 			}
8625 
8626 		/* When a reshape changes the number of devices,
8627 		 * ->degraded is measured against the larger of the
8628 		 * pre and post number of devices.
8629 		 */
8630 		spin_lock_irqsave(&conf->device_lock, flags);
8631 		mddev->degraded = raid5_calc_degraded(conf);
8632 		spin_unlock_irqrestore(&conf->device_lock, flags);
8633 	}
8634 	mddev->raid_disks = conf->raid_disks;
8635 	mddev->reshape_position = conf->reshape_progress;
8636 	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
8637 
8638 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
8639 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
8640 	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
8641 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
8642 	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
8643 	rcu_assign_pointer(mddev->sync_thread,
8644 			   md_register_thread(md_do_sync, mddev, "reshape"));
8645 	if (!mddev->sync_thread) {
8646 		mddev->recovery = 0;
8647 		spin_lock_irq(&conf->device_lock);
8648 		write_seqcount_begin(&conf->gen_lock);
8649 		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
8650 		mddev->new_chunk_sectors =
8651 			conf->chunk_sectors = conf->prev_chunk_sectors;
8652 		mddev->new_layout = conf->algorithm = conf->prev_algo;
8653 		rdev_for_each(rdev, mddev)
8654 			rdev->new_data_offset = rdev->data_offset;
8655 		smp_wmb();
8656 		conf->generation --;
8657 		conf->reshape_progress = MaxSector;
8658 		mddev->reshape_position = MaxSector;
8659 		write_seqcount_end(&conf->gen_lock);
8660 		spin_unlock_irq(&conf->device_lock);
8661 		return -EAGAIN;
8662 	}
8663 	conf->reshape_checkpoint = jiffies;
8664 	md_wakeup_thread(mddev->sync_thread);
8665 	md_new_event();
8666 	return 0;
8667 }
8668 
8669 /* This is called from the reshape thread and should make any
8670  * changes needed in 'conf'
8671  */
8672 static void end_reshape(struct r5conf *conf)
8673 {
8674 
8675 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
8676 		struct md_rdev *rdev;
8677 
8678 		spin_lock_irq(&conf->device_lock);
8679 		conf->previous_raid_disks = conf->raid_disks;
8680 		md_finish_reshape(conf->mddev);
8681 		smp_wmb();
8682 		conf->reshape_progress = MaxSector;
8683 		conf->mddev->reshape_position = MaxSector;
8684 		rdev_for_each(rdev, conf->mddev)
8685 			if (rdev->raid_disk >= 0 &&
8686 			    !test_bit(Journal, &rdev->flags) &&
8687 			    !test_bit(In_sync, &rdev->flags))
8688 				rdev->recovery_offset = MaxSector;
8689 		spin_unlock_irq(&conf->device_lock);
8690 		wake_up(&conf->wait_for_overlap);
8691 
8692 		if (conf->mddev->queue)
8693 			raid5_set_io_opt(conf);
8694 	}
8695 }
8696 
8697 /* This is called from the raid5d thread with mddev_lock held.
8698  * It makes config changes to the device.
8699  */
8700 static void raid5_finish_reshape(struct mddev *mddev)
8701 {
8702 	struct r5conf *conf = mddev->private;
8703 	struct md_rdev *rdev;
8704 
8705 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
8706 
8707 		if (mddev->delta_disks <= 0) {
8708 			int d;
8709 			spin_lock_irq(&conf->device_lock);
8710 			mddev->degraded = raid5_calc_degraded(conf);
8711 			spin_unlock_irq(&conf->device_lock);
8712 			for (d = conf->raid_disks ;
8713 			     d < conf->raid_disks - mddev->delta_disks;
8714 			     d++) {
8715 				rdev = rdev_mdlock_deref(mddev,
8716 							 conf->disks[d].rdev);
8717 				if (rdev)
8718 					clear_bit(In_sync, &rdev->flags);
8719 				rdev = rdev_mdlock_deref(mddev,
8720 						conf->disks[d].replacement);
8721 				if (rdev)
8722 					clear_bit(In_sync, &rdev->flags);
8723 			}
8724 		}
8725 		mddev->layout = conf->algorithm;
8726 		mddev->chunk_sectors = conf->chunk_sectors;
8727 		mddev->reshape_position = MaxSector;
8728 		mddev->delta_disks = 0;
8729 		mddev->reshape_backwards = 0;
8730 	}
8731 }
8732 
8733 static void raid5_quiesce(struct mddev *mddev, int quiesce)
8734 {
8735 	struct r5conf *conf = mddev->private;
8736 
8737 	if (quiesce) {
8738 		/* stop all writes */
8739 		lock_all_device_hash_locks_irq(conf);
8740 		/* '2' tells resync/reshape to pause so that all
8741 		 * active stripes can drain
8742 		 */
8743 		r5c_flush_cache(conf, INT_MAX);
8744 		/* need a memory barrier to make sure read_one_chunk() sees
8745 		 * quiesce started and reverts to slow (locked) path.
8746 		 */
8747 		smp_store_release(&conf->quiesce, 2);
8748 		wait_event_cmd(conf->wait_for_quiescent,
8749 				    atomic_read(&conf->active_stripes) == 0 &&
8750 				    atomic_read(&conf->active_aligned_reads) == 0,
8751 				    unlock_all_device_hash_locks_irq(conf),
8752 				    lock_all_device_hash_locks_irq(conf));
8753 		conf->quiesce = 1;
8754 		unlock_all_device_hash_locks_irq(conf);
8755 		/* allow reshape to continue */
8756 		wake_up(&conf->wait_for_overlap);
8757 	} else {
8758 		/* re-enable writes */
8759 		lock_all_device_hash_locks_irq(conf);
8760 		conf->quiesce = 0;
8761 		wake_up(&conf->wait_for_quiescent);
8762 		wake_up(&conf->wait_for_overlap);
8763 		unlock_all_device_hash_locks_irq(conf);
8764 	}
8765 	log_quiesce(conf, quiesce);
8766 }
8767 
8768 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
8769 {
8770 	struct r0conf *raid0_conf = mddev->private;
8771 	sector_t sectors;
8772 
8773 	/* for raid0 takeover only one zone is supported */
8774 	if (raid0_conf->nr_strip_zones > 1) {
8775 		pr_warn("md/raid:%s: cannot takeover raid0 with more than one zone.\n",
8776 			mdname(mddev));
8777 		return ERR_PTR(-EINVAL);
8778 	}
8779 
8780 	sectors = raid0_conf->strip_zone[0].zone_end;
8781 	sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
8782 	mddev->dev_sectors = sectors;
8783 	mddev->new_level = level;
8784 	mddev->new_layout = ALGORITHM_PARITY_N;
8785 	mddev->new_chunk_sectors = mddev->chunk_sectors;
8786 	mddev->raid_disks += 1;
8787 	mddev->delta_disks = 1;
8788 	/* make sure it will be not marked as dirty */
8789 	mddev->recovery_cp = MaxSector;
8790 
8791 	return setup_conf(mddev);
8792 }
8793 
8794 static void *raid5_takeover_raid1(struct mddev *mddev)
8795 {
8796 	int chunksect;
8797 	void *ret;
8798 
8799 	if (mddev->raid_disks != 2 ||
8800 	    mddev->degraded > 1)
8801 		return ERR_PTR(-EINVAL);
8802 
8803 	/* Should check if there are write-behind devices? */
8804 
8805 	chunksect = 64*2; /* 64K by default */
8806 
8807 	/* The array must be an exact multiple of chunksize */
8808 	while (chunksect && (mddev->array_sectors & (chunksect-1)))
8809 		chunksect >>= 1;
8810 
8811 	if ((chunksect<<9) < RAID5_STRIPE_SIZE((struct r5conf *)mddev->private))
8812 		/* array size does not allow a suitable chunk size */
8813 		return ERR_PTR(-EINVAL);
8814 
8815 	mddev->new_level = 5;
8816 	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
8817 	mddev->new_chunk_sectors = chunksect;
8818 
8819 	ret = setup_conf(mddev);
8820 	if (!IS_ERR(ret))
8821 		mddev_clear_unsupported_flags(mddev,
8822 			UNSUPPORTED_MDDEV_FLAGS);
8823 	return ret;
8824 }
8825 
8826 static void *raid5_takeover_raid6(struct mddev *mddev)
8827 {
8828 	int new_layout;
8829 
8830 	switch (mddev->layout) {
8831 	case ALGORITHM_LEFT_ASYMMETRIC_6:
8832 		new_layout = ALGORITHM_LEFT_ASYMMETRIC;
8833 		break;
8834 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
8835 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
8836 		break;
8837 	case ALGORITHM_LEFT_SYMMETRIC_6:
8838 		new_layout = ALGORITHM_LEFT_SYMMETRIC;
8839 		break;
8840 	case ALGORITHM_RIGHT_SYMMETRIC_6:
8841 		new_layout = ALGORITHM_RIGHT_SYMMETRIC;
8842 		break;
8843 	case ALGORITHM_PARITY_0_6:
8844 		new_layout = ALGORITHM_PARITY_0;
8845 		break;
8846 	case ALGORITHM_PARITY_N:
8847 		new_layout = ALGORITHM_PARITY_N;
8848 		break;
8849 	default:
8850 		return ERR_PTR(-EINVAL);
8851 	}
8852 	mddev->new_level = 5;
8853 	mddev->new_layout = new_layout;
8854 	mddev->delta_disks = -1;
8855 	mddev->raid_disks -= 1;
8856 	return setup_conf(mddev);
8857 }
8858 
8859 static int raid5_check_reshape(struct mddev *mddev)
8860 {
8861 	/* For a 2-drive array, the layout and chunk size can be changed
8862 	 * immediately as not restriping is needed.
8863 	 * For larger arrays we record the new value - after validation
8864 	 * to be used by a reshape pass.
8865 	 */
8866 	struct r5conf *conf = mddev->private;
8867 	int new_chunk = mddev->new_chunk_sectors;
8868 
8869 	if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
8870 		return -EINVAL;
8871 	if (new_chunk > 0) {
8872 		if (!is_power_of_2(new_chunk))
8873 			return -EINVAL;
8874 		if (new_chunk < (PAGE_SIZE>>9))
8875 			return -EINVAL;
8876 		if (mddev->array_sectors & (new_chunk-1))
8877 			/* not factor of array size */
8878 			return -EINVAL;
8879 	}
8880 
8881 	/* They look valid */
8882 
8883 	if (mddev->raid_disks == 2) {
8884 		/* can make the change immediately */
8885 		if (mddev->new_layout >= 0) {
8886 			conf->algorithm = mddev->new_layout;
8887 			mddev->layout = mddev->new_layout;
8888 		}
8889 		if (new_chunk > 0) {
8890 			conf->chunk_sectors = new_chunk ;
8891 			mddev->chunk_sectors = new_chunk;
8892 		}
8893 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
8894 		md_wakeup_thread(mddev->thread);
8895 	}
8896 	return check_reshape(mddev);
8897 }
8898 
8899 static int raid6_check_reshape(struct mddev *mddev)
8900 {
8901 	int new_chunk = mddev->new_chunk_sectors;
8902 
8903 	if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
8904 		return -EINVAL;
8905 	if (new_chunk > 0) {
8906 		if (!is_power_of_2(new_chunk))
8907 			return -EINVAL;
8908 		if (new_chunk < (PAGE_SIZE >> 9))
8909 			return -EINVAL;
8910 		if (mddev->array_sectors & (new_chunk-1))
8911 			/* not factor of array size */
8912 			return -EINVAL;
8913 	}
8914 
8915 	/* They look valid */
8916 	return check_reshape(mddev);
8917 }
8918 
8919 static void *raid5_takeover(struct mddev *mddev)
8920 {
8921 	/* raid5 can take over:
8922 	 *  raid0 - if there is only one strip zone - make it a raid4 layout
8923 	 *  raid1 - if there are two drives.  We need to know the chunk size
8924 	 *  raid4 - trivial - just use a raid4 layout.
8925 	 *  raid6 - Providing it is a *_6 layout
8926 	 */
8927 	if (mddev->level == 0)
8928 		return raid45_takeover_raid0(mddev, 5);
8929 	if (mddev->level == 1)
8930 		return raid5_takeover_raid1(mddev);
8931 	if (mddev->level == 4) {
8932 		mddev->new_layout = ALGORITHM_PARITY_N;
8933 		mddev->new_level = 5;
8934 		return setup_conf(mddev);
8935 	}
8936 	if (mddev->level == 6)
8937 		return raid5_takeover_raid6(mddev);
8938 
8939 	return ERR_PTR(-EINVAL);
8940 }
8941 
8942 static void *raid4_takeover(struct mddev *mddev)
8943 {
8944 	/* raid4 can take over:
8945 	 *  raid0 - if there is only one strip zone
8946 	 *  raid5 - if layout is right
8947 	 */
8948 	if (mddev->level == 0)
8949 		return raid45_takeover_raid0(mddev, 4);
8950 	if (mddev->level == 5 &&
8951 	    mddev->layout == ALGORITHM_PARITY_N) {
8952 		mddev->new_layout = 0;
8953 		mddev->new_level = 4;
8954 		return setup_conf(mddev);
8955 	}
8956 	return ERR_PTR(-EINVAL);
8957 }
8958 
8959 static struct md_personality raid5_personality;
8960 
8961 static void *raid6_takeover(struct mddev *mddev)
8962 {
8963 	/* Currently can only take over a raid5.  We map the
8964 	 * personality to an equivalent raid6 personality
8965 	 * with the Q block at the end.
8966 	 */
8967 	int new_layout;
8968 
8969 	if (mddev->pers != &raid5_personality)
8970 		return ERR_PTR(-EINVAL);
8971 	if (mddev->degraded > 1)
8972 		return ERR_PTR(-EINVAL);
8973 	if (mddev->raid_disks > 253)
8974 		return ERR_PTR(-EINVAL);
8975 	if (mddev->raid_disks < 3)
8976 		return ERR_PTR(-EINVAL);
8977 
8978 	switch (mddev->layout) {
8979 	case ALGORITHM_LEFT_ASYMMETRIC:
8980 		new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
8981 		break;
8982 	case ALGORITHM_RIGHT_ASYMMETRIC:
8983 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
8984 		break;
8985 	case ALGORITHM_LEFT_SYMMETRIC:
8986 		new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
8987 		break;
8988 	case ALGORITHM_RIGHT_SYMMETRIC:
8989 		new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
8990 		break;
8991 	case ALGORITHM_PARITY_0:
8992 		new_layout = ALGORITHM_PARITY_0_6;
8993 		break;
8994 	case ALGORITHM_PARITY_N:
8995 		new_layout = ALGORITHM_PARITY_N;
8996 		break;
8997 	default:
8998 		return ERR_PTR(-EINVAL);
8999 	}
9000 	mddev->new_level = 6;
9001 	mddev->new_layout = new_layout;
9002 	mddev->delta_disks = 1;
9003 	mddev->raid_disks += 1;
9004 	return setup_conf(mddev);
9005 }
9006 
9007 static int raid5_change_consistency_policy(struct mddev *mddev, const char *buf)
9008 {
9009 	struct r5conf *conf;
9010 	int err;
9011 
9012 	err = mddev_lock(mddev);
9013 	if (err)
9014 		return err;
9015 	conf = mddev->private;
9016 	if (!conf) {
9017 		mddev_unlock(mddev);
9018 		return -ENODEV;
9019 	}
9020 
9021 	if (strncmp(buf, "ppl", 3) == 0) {
9022 		/* ppl only works with RAID 5 */
9023 		if (!raid5_has_ppl(conf) && conf->level == 5) {
9024 			err = log_init(conf, NULL, true);
9025 			if (!err) {
9026 				err = resize_stripes(conf, conf->pool_size);
9027 				if (err) {
9028 					mddev_suspend(mddev);
9029 					log_exit(conf);
9030 					mddev_resume(mddev);
9031 				}
9032 			}
9033 		} else
9034 			err = -EINVAL;
9035 	} else if (strncmp(buf, "resync", 6) == 0) {
9036 		if (raid5_has_ppl(conf)) {
9037 			mddev_suspend(mddev);
9038 			log_exit(conf);
9039 			mddev_resume(mddev);
9040 			err = resize_stripes(conf, conf->pool_size);
9041 		} else if (test_bit(MD_HAS_JOURNAL, &conf->mddev->flags) &&
9042 			   r5l_log_disk_error(conf)) {
9043 			bool journal_dev_exists = false;
9044 			struct md_rdev *rdev;
9045 
9046 			rdev_for_each(rdev, mddev)
9047 				if (test_bit(Journal, &rdev->flags)) {
9048 					journal_dev_exists = true;
9049 					break;
9050 				}
9051 
9052 			if (!journal_dev_exists) {
9053 				mddev_suspend(mddev);
9054 				clear_bit(MD_HAS_JOURNAL, &mddev->flags);
9055 				mddev_resume(mddev);
9056 			} else  /* need remove journal device first */
9057 				err = -EBUSY;
9058 		} else
9059 			err = -EINVAL;
9060 	} else {
9061 		err = -EINVAL;
9062 	}
9063 
9064 	if (!err)
9065 		md_update_sb(mddev, 1);
9066 
9067 	mddev_unlock(mddev);
9068 
9069 	return err;
9070 }
9071 
9072 static int raid5_start(struct mddev *mddev)
9073 {
9074 	struct r5conf *conf = mddev->private;
9075 
9076 	return r5l_start(conf->log);
9077 }
9078 
9079 static void raid5_prepare_suspend(struct mddev *mddev)
9080 {
9081 	struct r5conf *conf = mddev->private;
9082 
9083 	wait_event(mddev->sb_wait, !reshape_inprogress(mddev) ||
9084 				    percpu_ref_is_zero(&mddev->active_io));
9085 	if (percpu_ref_is_zero(&mddev->active_io))
9086 		return;
9087 
9088 	/*
9089 	 * Reshape is not in progress, and array is suspended, io that is
9090 	 * waiting for reshpape can never be done.
9091 	 */
9092 	wake_up(&conf->wait_for_overlap);
9093 }
9094 
9095 static struct md_personality raid6_personality =
9096 {
9097 	.name		= "raid6",
9098 	.level		= 6,
9099 	.owner		= THIS_MODULE,
9100 	.make_request	= raid5_make_request,
9101 	.run		= raid5_run,
9102 	.start		= raid5_start,
9103 	.free		= raid5_free,
9104 	.status		= raid5_status,
9105 	.error_handler	= raid5_error,
9106 	.hot_add_disk	= raid5_add_disk,
9107 	.hot_remove_disk= raid5_remove_disk,
9108 	.spare_active	= raid5_spare_active,
9109 	.sync_request	= raid5_sync_request,
9110 	.resize		= raid5_resize,
9111 	.size		= raid5_size,
9112 	.check_reshape	= raid6_check_reshape,
9113 	.start_reshape  = raid5_start_reshape,
9114 	.finish_reshape = raid5_finish_reshape,
9115 	.prepare_suspend = raid5_prepare_suspend,
9116 	.quiesce	= raid5_quiesce,
9117 	.takeover	= raid6_takeover,
9118 	.change_consistency_policy = raid5_change_consistency_policy,
9119 };
9120 static struct md_personality raid5_personality =
9121 {
9122 	.name		= "raid5",
9123 	.level		= 5,
9124 	.owner		= THIS_MODULE,
9125 	.make_request	= raid5_make_request,
9126 	.run		= raid5_run,
9127 	.start		= raid5_start,
9128 	.free		= raid5_free,
9129 	.status		= raid5_status,
9130 	.error_handler	= raid5_error,
9131 	.hot_add_disk	= raid5_add_disk,
9132 	.hot_remove_disk= raid5_remove_disk,
9133 	.spare_active	= raid5_spare_active,
9134 	.sync_request	= raid5_sync_request,
9135 	.resize		= raid5_resize,
9136 	.size		= raid5_size,
9137 	.check_reshape	= raid5_check_reshape,
9138 	.start_reshape  = raid5_start_reshape,
9139 	.finish_reshape = raid5_finish_reshape,
9140 	.prepare_suspend = raid5_prepare_suspend,
9141 	.quiesce	= raid5_quiesce,
9142 	.takeover	= raid5_takeover,
9143 	.change_consistency_policy = raid5_change_consistency_policy,
9144 };
9145 
9146 static struct md_personality raid4_personality =
9147 {
9148 	.name		= "raid4",
9149 	.level		= 4,
9150 	.owner		= THIS_MODULE,
9151 	.make_request	= raid5_make_request,
9152 	.run		= raid5_run,
9153 	.start		= raid5_start,
9154 	.free		= raid5_free,
9155 	.status		= raid5_status,
9156 	.error_handler	= raid5_error,
9157 	.hot_add_disk	= raid5_add_disk,
9158 	.hot_remove_disk= raid5_remove_disk,
9159 	.spare_active	= raid5_spare_active,
9160 	.sync_request	= raid5_sync_request,
9161 	.resize		= raid5_resize,
9162 	.size		= raid5_size,
9163 	.check_reshape	= raid5_check_reshape,
9164 	.start_reshape  = raid5_start_reshape,
9165 	.finish_reshape = raid5_finish_reshape,
9166 	.prepare_suspend = raid5_prepare_suspend,
9167 	.quiesce	= raid5_quiesce,
9168 	.takeover	= raid4_takeover,
9169 	.change_consistency_policy = raid5_change_consistency_policy,
9170 };
9171 
9172 static int __init raid5_init(void)
9173 {
9174 	int ret;
9175 
9176 	raid5_wq = alloc_workqueue("raid5wq",
9177 		WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
9178 	if (!raid5_wq)
9179 		return -ENOMEM;
9180 
9181 	ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
9182 				      "md/raid5:prepare",
9183 				      raid456_cpu_up_prepare,
9184 				      raid456_cpu_dead);
9185 	if (ret) {
9186 		destroy_workqueue(raid5_wq);
9187 		return ret;
9188 	}
9189 	register_md_personality(&raid6_personality);
9190 	register_md_personality(&raid5_personality);
9191 	register_md_personality(&raid4_personality);
9192 	return 0;
9193 }
9194 
9195 static void raid5_exit(void)
9196 {
9197 	unregister_md_personality(&raid6_personality);
9198 	unregister_md_personality(&raid5_personality);
9199 	unregister_md_personality(&raid4_personality);
9200 	cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
9201 	destroy_workqueue(raid5_wq);
9202 }
9203 
9204 module_init(raid5_init);
9205 module_exit(raid5_exit);
9206 MODULE_LICENSE("GPL");
9207 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
9208 MODULE_ALIAS("md-personality-4"); /* RAID5 */
9209 MODULE_ALIAS("md-raid5");
9210 MODULE_ALIAS("md-raid4");
9211 MODULE_ALIAS("md-level-5");
9212 MODULE_ALIAS("md-level-4");
9213 MODULE_ALIAS("md-personality-8"); /* RAID6 */
9214 MODULE_ALIAS("md-raid6");
9215 MODULE_ALIAS("md-level-6");
9216 
9217 /* This used to be two separate modules, they were: */
9218 MODULE_ALIAS("raid5");
9219 MODULE_ALIAS("raid6");
9220