xref: /openbmc/linux/drivers/md/raid5.c (revision 4e1a33b1)
1 /*
2  * raid5.c : Multiple Devices driver for Linux
3  *	   Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
4  *	   Copyright (C) 1999, 2000 Ingo Molnar
5  *	   Copyright (C) 2002, 2003 H. Peter Anvin
6  *
7  * RAID-4/5/6 management functions.
8  * Thanks to Penguin Computing for making the RAID-6 development possible
9  * by donating a test server!
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2, or (at your option)
14  * any later version.
15  *
16  * You should have received a copy of the GNU General Public License
17  * (for example /usr/src/linux/COPYING); if not, write to the Free
18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 /*
22  * BITMAP UNPLUGGING:
23  *
24  * The sequencing for updating the bitmap reliably is a little
25  * subtle (and I got it wrong the first time) so it deserves some
26  * explanation.
27  *
28  * We group bitmap updates into batches.  Each batch has a number.
29  * We may write out several batches at once, but that isn't very important.
30  * conf->seq_write is the number of the last batch successfully written.
31  * conf->seq_flush is the number of the last batch that was closed to
32  *    new additions.
33  * When we discover that we will need to write to any block in a stripe
34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
35  * the number of the batch it will be in. This is seq_flush+1.
36  * When we are ready to do a write, if that batch hasn't been written yet,
37  *   we plug the array and queue the stripe for later.
38  * When an unplug happens, we increment bm_flush, thus closing the current
39  *   batch.
40  * When we notice that bm_flush > bm_write, we write out all pending updates
41  * to the bitmap, and advance bm_write to where bm_flush was.
42  * This may occasionally write a bit out twice, but is sure never to
43  * miss any bits.
44  */
45 
46 #include <linux/blkdev.h>
47 #include <linux/kthread.h>
48 #include <linux/raid/pq.h>
49 #include <linux/async_tx.h>
50 #include <linux/module.h>
51 #include <linux/async.h>
52 #include <linux/seq_file.h>
53 #include <linux/cpu.h>
54 #include <linux/slab.h>
55 #include <linux/ratelimit.h>
56 #include <linux/nodemask.h>
57 #include <linux/flex_array.h>
58 #include <trace/events/block.h>
59 
60 #include "md.h"
61 #include "raid5.h"
62 #include "raid0.h"
63 #include "bitmap.h"
64 
65 #define UNSUPPORTED_MDDEV_FLAGS	(1L << MD_FAILFAST_SUPPORTED)
66 
67 #define cpu_to_group(cpu) cpu_to_node(cpu)
68 #define ANY_GROUP NUMA_NO_NODE
69 
70 static bool devices_handle_discard_safely = false;
71 module_param(devices_handle_discard_safely, bool, 0644);
72 MODULE_PARM_DESC(devices_handle_discard_safely,
73 		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
74 static struct workqueue_struct *raid5_wq;
75 
76 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
77 {
78 	int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
79 	return &conf->stripe_hashtbl[hash];
80 }
81 
82 static inline int stripe_hash_locks_hash(sector_t sect)
83 {
84 	return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
85 }
86 
87 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
88 {
89 	spin_lock_irq(conf->hash_locks + hash);
90 	spin_lock(&conf->device_lock);
91 }
92 
93 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
94 {
95 	spin_unlock(&conf->device_lock);
96 	spin_unlock_irq(conf->hash_locks + hash);
97 }
98 
99 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
100 {
101 	int i;
102 	local_irq_disable();
103 	spin_lock(conf->hash_locks);
104 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
105 		spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
106 	spin_lock(&conf->device_lock);
107 }
108 
109 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
110 {
111 	int i;
112 	spin_unlock(&conf->device_lock);
113 	for (i = NR_STRIPE_HASH_LOCKS; i; i--)
114 		spin_unlock(conf->hash_locks + i - 1);
115 	local_irq_enable();
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 return_io(struct bio_list *return_bi)
158 {
159 	struct bio *bi;
160 	while ((bi = bio_list_pop(return_bi)) != NULL) {
161 		bi->bi_iter.bi_size = 0;
162 		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
163 					 bi, 0);
164 		bio_endio(bi);
165 	}
166 }
167 
168 static void print_raid5_conf (struct r5conf *conf);
169 
170 static int stripe_operations_active(struct stripe_head *sh)
171 {
172 	return sh->check_state || sh->reconstruct_state ||
173 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
174 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
175 }
176 
177 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
178 {
179 	struct r5conf *conf = sh->raid_conf;
180 	struct r5worker_group *group;
181 	int thread_cnt;
182 	int i, cpu = sh->cpu;
183 
184 	if (!cpu_online(cpu)) {
185 		cpu = cpumask_any(cpu_online_mask);
186 		sh->cpu = cpu;
187 	}
188 
189 	if (list_empty(&sh->lru)) {
190 		struct r5worker_group *group;
191 		group = conf->worker_groups + cpu_to_group(cpu);
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 {
223 	int i;
224 	int injournal = 0;	/* number of date pages with R5_InJournal */
225 
226 	BUG_ON(!list_empty(&sh->lru));
227 	BUG_ON(atomic_read(&conf->active_stripes)==0);
228 
229 	if (r5c_is_writeback(conf->log))
230 		for (i = sh->disks; i--; )
231 			if (test_bit(R5_InJournal, &sh->dev[i].flags))
232 				injournal++;
233 	/*
234 	 * When quiesce in r5c write back, set STRIPE_HANDLE for stripes with
235 	 * data in journal, so they are not released to cached lists
236 	 */
237 	if (conf->quiesce && r5c_is_writeback(conf->log) &&
238 	    !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0) {
239 		if (test_bit(STRIPE_R5C_CACHING, &sh->state))
240 			r5c_make_stripe_write_out(sh);
241 		set_bit(STRIPE_HANDLE, &sh->state);
242 	}
243 
244 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
245 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
246 		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
247 			list_add_tail(&sh->lru, &conf->delayed_list);
248 		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
249 			   sh->bm_seq - conf->seq_write > 0)
250 			list_add_tail(&sh->lru, &conf->bitmap_list);
251 		else {
252 			clear_bit(STRIPE_DELAYED, &sh->state);
253 			clear_bit(STRIPE_BIT_DELAY, &sh->state);
254 			if (conf->worker_cnt_per_group == 0) {
255 				list_add_tail(&sh->lru, &conf->handle_list);
256 			} else {
257 				raid5_wakeup_stripe_thread(sh);
258 				return;
259 			}
260 		}
261 		md_wakeup_thread(conf->mddev->thread);
262 	} else {
263 		BUG_ON(stripe_operations_active(sh));
264 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
265 			if (atomic_dec_return(&conf->preread_active_stripes)
266 			    < IO_THRESHOLD)
267 				md_wakeup_thread(conf->mddev->thread);
268 		atomic_dec(&conf->active_stripes);
269 		if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
270 			if (!r5c_is_writeback(conf->log))
271 				list_add_tail(&sh->lru, temp_inactive_list);
272 			else {
273 				WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
274 				if (injournal == 0)
275 					list_add_tail(&sh->lru, temp_inactive_list);
276 				else if (injournal == conf->raid_disks - conf->max_degraded) {
277 					/* full stripe */
278 					if (!test_and_set_bit(STRIPE_R5C_FULL_STRIPE, &sh->state))
279 						atomic_inc(&conf->r5c_cached_full_stripes);
280 					if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
281 						atomic_dec(&conf->r5c_cached_partial_stripes);
282 					list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
283 					r5c_check_cached_full_stripe(conf);
284 				} else {
285 					/* partial stripe */
286 					if (!test_and_set_bit(STRIPE_R5C_PARTIAL_STRIPE,
287 							      &sh->state))
288 						atomic_inc(&conf->r5c_cached_partial_stripes);
289 					list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
290 				}
291 			}
292 		}
293 	}
294 }
295 
296 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
297 			     struct list_head *temp_inactive_list)
298 {
299 	if (atomic_dec_and_test(&sh->count))
300 		do_release_stripe(conf, sh, temp_inactive_list);
301 }
302 
303 /*
304  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
305  *
306  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
307  * given time. Adding stripes only takes device lock, while deleting stripes
308  * only takes hash lock.
309  */
310 static void release_inactive_stripe_list(struct r5conf *conf,
311 					 struct list_head *temp_inactive_list,
312 					 int hash)
313 {
314 	int size;
315 	bool do_wakeup = false;
316 	unsigned long flags;
317 
318 	if (hash == NR_STRIPE_HASH_LOCKS) {
319 		size = NR_STRIPE_HASH_LOCKS;
320 		hash = NR_STRIPE_HASH_LOCKS - 1;
321 	} else
322 		size = 1;
323 	while (size) {
324 		struct list_head *list = &temp_inactive_list[size - 1];
325 
326 		/*
327 		 * We don't hold any lock here yet, raid5_get_active_stripe() might
328 		 * remove stripes from the list
329 		 */
330 		if (!list_empty_careful(list)) {
331 			spin_lock_irqsave(conf->hash_locks + hash, flags);
332 			if (list_empty(conf->inactive_list + hash) &&
333 			    !list_empty(list))
334 				atomic_dec(&conf->empty_inactive_list_nr);
335 			list_splice_tail_init(list, conf->inactive_list + hash);
336 			do_wakeup = true;
337 			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
338 		}
339 		size--;
340 		hash--;
341 	}
342 
343 	if (do_wakeup) {
344 		wake_up(&conf->wait_for_stripe);
345 		if (atomic_read(&conf->active_stripes) == 0)
346 			wake_up(&conf->wait_for_quiescent);
347 		if (conf->retry_read_aligned)
348 			md_wakeup_thread(conf->mddev->thread);
349 	}
350 }
351 
352 /* should hold conf->device_lock already */
353 static int release_stripe_list(struct r5conf *conf,
354 			       struct list_head *temp_inactive_list)
355 {
356 	struct stripe_head *sh;
357 	int count = 0;
358 	struct llist_node *head;
359 
360 	head = llist_del_all(&conf->released_stripes);
361 	head = llist_reverse_order(head);
362 	while (head) {
363 		int hash;
364 
365 		sh = llist_entry(head, struct stripe_head, release_list);
366 		head = llist_next(head);
367 		/* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
368 		smp_mb();
369 		clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
370 		/*
371 		 * Don't worry the bit is set here, because if the bit is set
372 		 * again, the count is always > 1. This is true for
373 		 * STRIPE_ON_UNPLUG_LIST bit too.
374 		 */
375 		hash = sh->hash_lock_index;
376 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
377 		count++;
378 	}
379 
380 	return count;
381 }
382 
383 void raid5_release_stripe(struct stripe_head *sh)
384 {
385 	struct r5conf *conf = sh->raid_conf;
386 	unsigned long flags;
387 	struct list_head list;
388 	int hash;
389 	bool wakeup;
390 
391 	/* Avoid release_list until the last reference.
392 	 */
393 	if (atomic_add_unless(&sh->count, -1, 1))
394 		return;
395 
396 	if (unlikely(!conf->mddev->thread) ||
397 		test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
398 		goto slow_path;
399 	wakeup = llist_add(&sh->release_list, &conf->released_stripes);
400 	if (wakeup)
401 		md_wakeup_thread(conf->mddev->thread);
402 	return;
403 slow_path:
404 	local_irq_save(flags);
405 	/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
406 	if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
407 		INIT_LIST_HEAD(&list);
408 		hash = sh->hash_lock_index;
409 		do_release_stripe(conf, sh, &list);
410 		spin_unlock(&conf->device_lock);
411 		release_inactive_stripe_list(conf, &list, hash);
412 	}
413 	local_irq_restore(flags);
414 }
415 
416 static inline void remove_hash(struct stripe_head *sh)
417 {
418 	pr_debug("remove_hash(), stripe %llu\n",
419 		(unsigned long long)sh->sector);
420 
421 	hlist_del_init(&sh->hash);
422 }
423 
424 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
425 {
426 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
427 
428 	pr_debug("insert_hash(), stripe %llu\n",
429 		(unsigned long long)sh->sector);
430 
431 	hlist_add_head(&sh->hash, hp);
432 }
433 
434 /* find an idle stripe, make sure it is unhashed, and return it. */
435 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
436 {
437 	struct stripe_head *sh = NULL;
438 	struct list_head *first;
439 
440 	if (list_empty(conf->inactive_list + hash))
441 		goto out;
442 	first = (conf->inactive_list + hash)->next;
443 	sh = list_entry(first, struct stripe_head, lru);
444 	list_del_init(first);
445 	remove_hash(sh);
446 	atomic_inc(&conf->active_stripes);
447 	BUG_ON(hash != sh->hash_lock_index);
448 	if (list_empty(conf->inactive_list + hash))
449 		atomic_inc(&conf->empty_inactive_list_nr);
450 out:
451 	return sh;
452 }
453 
454 static void shrink_buffers(struct stripe_head *sh)
455 {
456 	struct page *p;
457 	int i;
458 	int num = sh->raid_conf->pool_size;
459 
460 	for (i = 0; i < num ; i++) {
461 		WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
462 		p = sh->dev[i].page;
463 		if (!p)
464 			continue;
465 		sh->dev[i].page = NULL;
466 		put_page(p);
467 	}
468 }
469 
470 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
471 {
472 	int i;
473 	int num = sh->raid_conf->pool_size;
474 
475 	for (i = 0; i < num; i++) {
476 		struct page *page;
477 
478 		if (!(page = alloc_page(gfp))) {
479 			return 1;
480 		}
481 		sh->dev[i].page = page;
482 		sh->dev[i].orig_page = page;
483 	}
484 	return 0;
485 }
486 
487 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
488 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
489 			    struct stripe_head *sh);
490 
491 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
492 {
493 	struct r5conf *conf = sh->raid_conf;
494 	int i, seq;
495 
496 	BUG_ON(atomic_read(&sh->count) != 0);
497 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
498 	BUG_ON(stripe_operations_active(sh));
499 	BUG_ON(sh->batch_head);
500 
501 	pr_debug("init_stripe called, stripe %llu\n",
502 		(unsigned long long)sector);
503 retry:
504 	seq = read_seqcount_begin(&conf->gen_lock);
505 	sh->generation = conf->generation - previous;
506 	sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
507 	sh->sector = sector;
508 	stripe_set_idx(sector, conf, previous, sh);
509 	sh->state = 0;
510 
511 	for (i = sh->disks; i--; ) {
512 		struct r5dev *dev = &sh->dev[i];
513 
514 		if (dev->toread || dev->read || dev->towrite || dev->written ||
515 		    test_bit(R5_LOCKED, &dev->flags)) {
516 			pr_err("sector=%llx i=%d %p %p %p %p %d\n",
517 			       (unsigned long long)sh->sector, i, dev->toread,
518 			       dev->read, dev->towrite, dev->written,
519 			       test_bit(R5_LOCKED, &dev->flags));
520 			WARN_ON(1);
521 		}
522 		dev->flags = 0;
523 		raid5_build_block(sh, i, previous);
524 	}
525 	if (read_seqcount_retry(&conf->gen_lock, seq))
526 		goto retry;
527 	sh->overwrite_disks = 0;
528 	insert_hash(conf, sh);
529 	sh->cpu = smp_processor_id();
530 	set_bit(STRIPE_BATCH_READY, &sh->state);
531 }
532 
533 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
534 					 short generation)
535 {
536 	struct stripe_head *sh;
537 
538 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
539 	hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
540 		if (sh->sector == sector && sh->generation == generation)
541 			return sh;
542 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
543 	return NULL;
544 }
545 
546 /*
547  * Need to check if array has failed when deciding whether to:
548  *  - start an array
549  *  - remove non-faulty devices
550  *  - add a spare
551  *  - allow a reshape
552  * This determination is simple when no reshape is happening.
553  * However if there is a reshape, we need to carefully check
554  * both the before and after sections.
555  * This is because some failed devices may only affect one
556  * of the two sections, and some non-in_sync devices may
557  * be insync in the section most affected by failed devices.
558  */
559 int raid5_calc_degraded(struct r5conf *conf)
560 {
561 	int degraded, degraded2;
562 	int i;
563 
564 	rcu_read_lock();
565 	degraded = 0;
566 	for (i = 0; i < conf->previous_raid_disks; i++) {
567 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
568 		if (rdev && test_bit(Faulty, &rdev->flags))
569 			rdev = rcu_dereference(conf->disks[i].replacement);
570 		if (!rdev || test_bit(Faulty, &rdev->flags))
571 			degraded++;
572 		else if (test_bit(In_sync, &rdev->flags))
573 			;
574 		else
575 			/* not in-sync or faulty.
576 			 * If the reshape increases the number of devices,
577 			 * this is being recovered by the reshape, so
578 			 * this 'previous' section is not in_sync.
579 			 * If the number of devices is being reduced however,
580 			 * the device can only be part of the array if
581 			 * we are reverting a reshape, so this section will
582 			 * be in-sync.
583 			 */
584 			if (conf->raid_disks >= conf->previous_raid_disks)
585 				degraded++;
586 	}
587 	rcu_read_unlock();
588 	if (conf->raid_disks == conf->previous_raid_disks)
589 		return degraded;
590 	rcu_read_lock();
591 	degraded2 = 0;
592 	for (i = 0; i < conf->raid_disks; i++) {
593 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
594 		if (rdev && test_bit(Faulty, &rdev->flags))
595 			rdev = rcu_dereference(conf->disks[i].replacement);
596 		if (!rdev || test_bit(Faulty, &rdev->flags))
597 			degraded2++;
598 		else if (test_bit(In_sync, &rdev->flags))
599 			;
600 		else
601 			/* not in-sync or faulty.
602 			 * If reshape increases the number of devices, this
603 			 * section has already been recovered, else it
604 			 * almost certainly hasn't.
605 			 */
606 			if (conf->raid_disks <= conf->previous_raid_disks)
607 				degraded2++;
608 	}
609 	rcu_read_unlock();
610 	if (degraded2 > degraded)
611 		return degraded2;
612 	return degraded;
613 }
614 
615 static int has_failed(struct r5conf *conf)
616 {
617 	int degraded;
618 
619 	if (conf->mddev->reshape_position == MaxSector)
620 		return conf->mddev->degraded > conf->max_degraded;
621 
622 	degraded = raid5_calc_degraded(conf);
623 	if (degraded > conf->max_degraded)
624 		return 1;
625 	return 0;
626 }
627 
628 struct stripe_head *
629 raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
630 			int previous, int noblock, int noquiesce)
631 {
632 	struct stripe_head *sh;
633 	int hash = stripe_hash_locks_hash(sector);
634 	int inc_empty_inactive_list_flag;
635 
636 	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
637 
638 	spin_lock_irq(conf->hash_locks + hash);
639 
640 	do {
641 		wait_event_lock_irq(conf->wait_for_quiescent,
642 				    conf->quiesce == 0 || noquiesce,
643 				    *(conf->hash_locks + hash));
644 		sh = __find_stripe(conf, sector, conf->generation - previous);
645 		if (!sh) {
646 			if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
647 				sh = get_free_stripe(conf, hash);
648 				if (!sh && !test_bit(R5_DID_ALLOC,
649 						     &conf->cache_state))
650 					set_bit(R5_ALLOC_MORE,
651 						&conf->cache_state);
652 			}
653 			if (noblock && sh == NULL)
654 				break;
655 
656 			r5c_check_stripe_cache_usage(conf);
657 			if (!sh) {
658 				set_bit(R5_INACTIVE_BLOCKED,
659 					&conf->cache_state);
660 				r5l_wake_reclaim(conf->log, 0);
661 				wait_event_lock_irq(
662 					conf->wait_for_stripe,
663 					!list_empty(conf->inactive_list + hash) &&
664 					(atomic_read(&conf->active_stripes)
665 					 < (conf->max_nr_stripes * 3 / 4)
666 					 || !test_bit(R5_INACTIVE_BLOCKED,
667 						      &conf->cache_state)),
668 					*(conf->hash_locks + hash));
669 				clear_bit(R5_INACTIVE_BLOCKED,
670 					  &conf->cache_state);
671 			} else {
672 				init_stripe(sh, sector, previous);
673 				atomic_inc(&sh->count);
674 			}
675 		} else if (!atomic_inc_not_zero(&sh->count)) {
676 			spin_lock(&conf->device_lock);
677 			if (!atomic_read(&sh->count)) {
678 				if (!test_bit(STRIPE_HANDLE, &sh->state))
679 					atomic_inc(&conf->active_stripes);
680 				BUG_ON(list_empty(&sh->lru) &&
681 				       !test_bit(STRIPE_EXPANDING, &sh->state));
682 				inc_empty_inactive_list_flag = 0;
683 				if (!list_empty(conf->inactive_list + hash))
684 					inc_empty_inactive_list_flag = 1;
685 				list_del_init(&sh->lru);
686 				if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
687 					atomic_inc(&conf->empty_inactive_list_nr);
688 				if (sh->group) {
689 					sh->group->stripes_cnt--;
690 					sh->group = NULL;
691 				}
692 			}
693 			atomic_inc(&sh->count);
694 			spin_unlock(&conf->device_lock);
695 		}
696 	} while (sh == NULL);
697 
698 	spin_unlock_irq(conf->hash_locks + hash);
699 	return sh;
700 }
701 
702 static bool is_full_stripe_write(struct stripe_head *sh)
703 {
704 	BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
705 	return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
706 }
707 
708 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
709 {
710 	local_irq_disable();
711 	if (sh1 > sh2) {
712 		spin_lock(&sh2->stripe_lock);
713 		spin_lock_nested(&sh1->stripe_lock, 1);
714 	} else {
715 		spin_lock(&sh1->stripe_lock);
716 		spin_lock_nested(&sh2->stripe_lock, 1);
717 	}
718 }
719 
720 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
721 {
722 	spin_unlock(&sh1->stripe_lock);
723 	spin_unlock(&sh2->stripe_lock);
724 	local_irq_enable();
725 }
726 
727 /* Only freshly new full stripe normal write stripe can be added to a batch list */
728 static bool stripe_can_batch(struct stripe_head *sh)
729 {
730 	struct r5conf *conf = sh->raid_conf;
731 
732 	if (conf->log)
733 		return false;
734 	return test_bit(STRIPE_BATCH_READY, &sh->state) &&
735 		!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
736 		is_full_stripe_write(sh);
737 }
738 
739 /* we only do back search */
740 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
741 {
742 	struct stripe_head *head;
743 	sector_t head_sector, tmp_sec;
744 	int hash;
745 	int dd_idx;
746 	int inc_empty_inactive_list_flag;
747 
748 	/* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
749 	tmp_sec = sh->sector;
750 	if (!sector_div(tmp_sec, conf->chunk_sectors))
751 		return;
752 	head_sector = sh->sector - STRIPE_SECTORS;
753 
754 	hash = stripe_hash_locks_hash(head_sector);
755 	spin_lock_irq(conf->hash_locks + hash);
756 	head = __find_stripe(conf, head_sector, conf->generation);
757 	if (head && !atomic_inc_not_zero(&head->count)) {
758 		spin_lock(&conf->device_lock);
759 		if (!atomic_read(&head->count)) {
760 			if (!test_bit(STRIPE_HANDLE, &head->state))
761 				atomic_inc(&conf->active_stripes);
762 			BUG_ON(list_empty(&head->lru) &&
763 			       !test_bit(STRIPE_EXPANDING, &head->state));
764 			inc_empty_inactive_list_flag = 0;
765 			if (!list_empty(conf->inactive_list + hash))
766 				inc_empty_inactive_list_flag = 1;
767 			list_del_init(&head->lru);
768 			if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
769 				atomic_inc(&conf->empty_inactive_list_nr);
770 			if (head->group) {
771 				head->group->stripes_cnt--;
772 				head->group = NULL;
773 			}
774 		}
775 		atomic_inc(&head->count);
776 		spin_unlock(&conf->device_lock);
777 	}
778 	spin_unlock_irq(conf->hash_locks + hash);
779 
780 	if (!head)
781 		return;
782 	if (!stripe_can_batch(head))
783 		goto out;
784 
785 	lock_two_stripes(head, sh);
786 	/* clear_batch_ready clear the flag */
787 	if (!stripe_can_batch(head) || !stripe_can_batch(sh))
788 		goto unlock_out;
789 
790 	if (sh->batch_head)
791 		goto unlock_out;
792 
793 	dd_idx = 0;
794 	while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
795 		dd_idx++;
796 	if (head->dev[dd_idx].towrite->bi_opf != sh->dev[dd_idx].towrite->bi_opf ||
797 	    bio_op(head->dev[dd_idx].towrite) != bio_op(sh->dev[dd_idx].towrite))
798 		goto unlock_out;
799 
800 	if (head->batch_head) {
801 		spin_lock(&head->batch_head->batch_lock);
802 		/* This batch list is already running */
803 		if (!stripe_can_batch(head)) {
804 			spin_unlock(&head->batch_head->batch_lock);
805 			goto unlock_out;
806 		}
807 
808 		/*
809 		 * at this point, head's BATCH_READY could be cleared, but we
810 		 * can still add the stripe to batch list
811 		 */
812 		list_add(&sh->batch_list, &head->batch_list);
813 		spin_unlock(&head->batch_head->batch_lock);
814 
815 		sh->batch_head = head->batch_head;
816 	} else {
817 		head->batch_head = head;
818 		sh->batch_head = head->batch_head;
819 		spin_lock(&head->batch_lock);
820 		list_add_tail(&sh->batch_list, &head->batch_list);
821 		spin_unlock(&head->batch_lock);
822 	}
823 
824 	if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
825 		if (atomic_dec_return(&conf->preread_active_stripes)
826 		    < IO_THRESHOLD)
827 			md_wakeup_thread(conf->mddev->thread);
828 
829 	if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
830 		int seq = sh->bm_seq;
831 		if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
832 		    sh->batch_head->bm_seq > seq)
833 			seq = sh->batch_head->bm_seq;
834 		set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
835 		sh->batch_head->bm_seq = seq;
836 	}
837 
838 	atomic_inc(&sh->count);
839 unlock_out:
840 	unlock_two_stripes(head, sh);
841 out:
842 	raid5_release_stripe(head);
843 }
844 
845 /* Determine if 'data_offset' or 'new_data_offset' should be used
846  * in this stripe_head.
847  */
848 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
849 {
850 	sector_t progress = conf->reshape_progress;
851 	/* Need a memory barrier to make sure we see the value
852 	 * of conf->generation, or ->data_offset that was set before
853 	 * reshape_progress was updated.
854 	 */
855 	smp_rmb();
856 	if (progress == MaxSector)
857 		return 0;
858 	if (sh->generation == conf->generation - 1)
859 		return 0;
860 	/* We are in a reshape, and this is a new-generation stripe,
861 	 * so use new_data_offset.
862 	 */
863 	return 1;
864 }
865 
866 static void
867 raid5_end_read_request(struct bio *bi);
868 static void
869 raid5_end_write_request(struct bio *bi);
870 
871 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
872 {
873 	struct r5conf *conf = sh->raid_conf;
874 	int i, disks = sh->disks;
875 	struct stripe_head *head_sh = sh;
876 
877 	might_sleep();
878 
879 	if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
880 		/* writing out phase */
881 		if (s->waiting_extra_page)
882 			return;
883 		if (r5l_write_stripe(conf->log, sh) == 0)
884 			return;
885 	} else {  /* caching phase */
886 		if (test_bit(STRIPE_LOG_TRAPPED, &sh->state)) {
887 			r5c_cache_data(conf->log, sh, s);
888 			return;
889 		}
890 	}
891 
892 	for (i = disks; i--; ) {
893 		int op, op_flags = 0;
894 		int replace_only = 0;
895 		struct bio *bi, *rbi;
896 		struct md_rdev *rdev, *rrdev = NULL;
897 
898 		sh = head_sh;
899 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
900 			op = REQ_OP_WRITE;
901 			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
902 				op_flags = REQ_FUA;
903 			if (test_bit(R5_Discard, &sh->dev[i].flags))
904 				op = REQ_OP_DISCARD;
905 		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
906 			op = REQ_OP_READ;
907 		else if (test_and_clear_bit(R5_WantReplace,
908 					    &sh->dev[i].flags)) {
909 			op = REQ_OP_WRITE;
910 			replace_only = 1;
911 		} else
912 			continue;
913 		if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
914 			op_flags |= REQ_SYNC;
915 
916 again:
917 		bi = &sh->dev[i].req;
918 		rbi = &sh->dev[i].rreq; /* For writing to replacement */
919 
920 		rcu_read_lock();
921 		rrdev = rcu_dereference(conf->disks[i].replacement);
922 		smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
923 		rdev = rcu_dereference(conf->disks[i].rdev);
924 		if (!rdev) {
925 			rdev = rrdev;
926 			rrdev = NULL;
927 		}
928 		if (op_is_write(op)) {
929 			if (replace_only)
930 				rdev = NULL;
931 			if (rdev == rrdev)
932 				/* We raced and saw duplicates */
933 				rrdev = NULL;
934 		} else {
935 			if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
936 				rdev = rrdev;
937 			rrdev = NULL;
938 		}
939 
940 		if (rdev && test_bit(Faulty, &rdev->flags))
941 			rdev = NULL;
942 		if (rdev)
943 			atomic_inc(&rdev->nr_pending);
944 		if (rrdev && test_bit(Faulty, &rrdev->flags))
945 			rrdev = NULL;
946 		if (rrdev)
947 			atomic_inc(&rrdev->nr_pending);
948 		rcu_read_unlock();
949 
950 		/* We have already checked bad blocks for reads.  Now
951 		 * need to check for writes.  We never accept write errors
952 		 * on the replacement, so we don't to check rrdev.
953 		 */
954 		while (op_is_write(op) && rdev &&
955 		       test_bit(WriteErrorSeen, &rdev->flags)) {
956 			sector_t first_bad;
957 			int bad_sectors;
958 			int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
959 					      &first_bad, &bad_sectors);
960 			if (!bad)
961 				break;
962 
963 			if (bad < 0) {
964 				set_bit(BlockedBadBlocks, &rdev->flags);
965 				if (!conf->mddev->external &&
966 				    conf->mddev->sb_flags) {
967 					/* It is very unlikely, but we might
968 					 * still need to write out the
969 					 * bad block log - better give it
970 					 * a chance*/
971 					md_check_recovery(conf->mddev);
972 				}
973 				/*
974 				 * Because md_wait_for_blocked_rdev
975 				 * will dec nr_pending, we must
976 				 * increment it first.
977 				 */
978 				atomic_inc(&rdev->nr_pending);
979 				md_wait_for_blocked_rdev(rdev, conf->mddev);
980 			} else {
981 				/* Acknowledged bad block - skip the write */
982 				rdev_dec_pending(rdev, conf->mddev);
983 				rdev = NULL;
984 			}
985 		}
986 
987 		if (rdev) {
988 			if (s->syncing || s->expanding || s->expanded
989 			    || s->replacing)
990 				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
991 
992 			set_bit(STRIPE_IO_STARTED, &sh->state);
993 
994 			bi->bi_bdev = rdev->bdev;
995 			bio_set_op_attrs(bi, op, op_flags);
996 			bi->bi_end_io = op_is_write(op)
997 				? raid5_end_write_request
998 				: raid5_end_read_request;
999 			bi->bi_private = sh;
1000 
1001 			pr_debug("%s: for %llu schedule op %d on disc %d\n",
1002 				__func__, (unsigned long long)sh->sector,
1003 				bi->bi_opf, i);
1004 			atomic_inc(&sh->count);
1005 			if (sh != head_sh)
1006 				atomic_inc(&head_sh->count);
1007 			if (use_new_offset(conf, sh))
1008 				bi->bi_iter.bi_sector = (sh->sector
1009 						 + rdev->new_data_offset);
1010 			else
1011 				bi->bi_iter.bi_sector = (sh->sector
1012 						 + rdev->data_offset);
1013 			if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1014 				bi->bi_opf |= REQ_NOMERGE;
1015 
1016 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1017 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1018 
1019 			if (!op_is_write(op) &&
1020 			    test_bit(R5_InJournal, &sh->dev[i].flags))
1021 				/*
1022 				 * issuing read for a page in journal, this
1023 				 * must be preparing for prexor in rmw; read
1024 				 * the data into orig_page
1025 				 */
1026 				sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
1027 			else
1028 				sh->dev[i].vec.bv_page = sh->dev[i].page;
1029 			bi->bi_vcnt = 1;
1030 			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1031 			bi->bi_io_vec[0].bv_offset = 0;
1032 			bi->bi_iter.bi_size = STRIPE_SIZE;
1033 			/*
1034 			 * If this is discard request, set bi_vcnt 0. We don't
1035 			 * want to confuse SCSI because SCSI will replace payload
1036 			 */
1037 			if (op == REQ_OP_DISCARD)
1038 				bi->bi_vcnt = 0;
1039 			if (rrdev)
1040 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1041 
1042 			if (conf->mddev->gendisk)
1043 				trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
1044 						      bi, disk_devt(conf->mddev->gendisk),
1045 						      sh->dev[i].sector);
1046 			generic_make_request(bi);
1047 		}
1048 		if (rrdev) {
1049 			if (s->syncing || s->expanding || s->expanded
1050 			    || s->replacing)
1051 				md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1052 
1053 			set_bit(STRIPE_IO_STARTED, &sh->state);
1054 
1055 			rbi->bi_bdev = rrdev->bdev;
1056 			bio_set_op_attrs(rbi, op, op_flags);
1057 			BUG_ON(!op_is_write(op));
1058 			rbi->bi_end_io = raid5_end_write_request;
1059 			rbi->bi_private = sh;
1060 
1061 			pr_debug("%s: for %llu schedule op %d on "
1062 				 "replacement disc %d\n",
1063 				__func__, (unsigned long long)sh->sector,
1064 				rbi->bi_opf, i);
1065 			atomic_inc(&sh->count);
1066 			if (sh != head_sh)
1067 				atomic_inc(&head_sh->count);
1068 			if (use_new_offset(conf, sh))
1069 				rbi->bi_iter.bi_sector = (sh->sector
1070 						  + rrdev->new_data_offset);
1071 			else
1072 				rbi->bi_iter.bi_sector = (sh->sector
1073 						  + rrdev->data_offset);
1074 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1075 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1076 			sh->dev[i].rvec.bv_page = sh->dev[i].page;
1077 			rbi->bi_vcnt = 1;
1078 			rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1079 			rbi->bi_io_vec[0].bv_offset = 0;
1080 			rbi->bi_iter.bi_size = STRIPE_SIZE;
1081 			/*
1082 			 * If this is discard request, set bi_vcnt 0. We don't
1083 			 * want to confuse SCSI because SCSI will replace payload
1084 			 */
1085 			if (op == REQ_OP_DISCARD)
1086 				rbi->bi_vcnt = 0;
1087 			if (conf->mddev->gendisk)
1088 				trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
1089 						      rbi, disk_devt(conf->mddev->gendisk),
1090 						      sh->dev[i].sector);
1091 			generic_make_request(rbi);
1092 		}
1093 		if (!rdev && !rrdev) {
1094 			if (op_is_write(op))
1095 				set_bit(STRIPE_DEGRADED, &sh->state);
1096 			pr_debug("skip op %d on disc %d for sector %llu\n",
1097 				bi->bi_opf, i, (unsigned long long)sh->sector);
1098 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
1099 			set_bit(STRIPE_HANDLE, &sh->state);
1100 		}
1101 
1102 		if (!head_sh->batch_head)
1103 			continue;
1104 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1105 				      batch_list);
1106 		if (sh != head_sh)
1107 			goto again;
1108 	}
1109 }
1110 
1111 static struct dma_async_tx_descriptor *
1112 async_copy_data(int frombio, struct bio *bio, struct page **page,
1113 	sector_t sector, struct dma_async_tx_descriptor *tx,
1114 	struct stripe_head *sh, int no_skipcopy)
1115 {
1116 	struct bio_vec bvl;
1117 	struct bvec_iter iter;
1118 	struct page *bio_page;
1119 	int page_offset;
1120 	struct async_submit_ctl submit;
1121 	enum async_tx_flags flags = 0;
1122 
1123 	if (bio->bi_iter.bi_sector >= sector)
1124 		page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1125 	else
1126 		page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1127 
1128 	if (frombio)
1129 		flags |= ASYNC_TX_FENCE;
1130 	init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1131 
1132 	bio_for_each_segment(bvl, bio, iter) {
1133 		int len = bvl.bv_len;
1134 		int clen;
1135 		int b_offset = 0;
1136 
1137 		if (page_offset < 0) {
1138 			b_offset = -page_offset;
1139 			page_offset += b_offset;
1140 			len -= b_offset;
1141 		}
1142 
1143 		if (len > 0 && page_offset + len > STRIPE_SIZE)
1144 			clen = STRIPE_SIZE - page_offset;
1145 		else
1146 			clen = len;
1147 
1148 		if (clen > 0) {
1149 			b_offset += bvl.bv_offset;
1150 			bio_page = bvl.bv_page;
1151 			if (frombio) {
1152 				if (sh->raid_conf->skip_copy &&
1153 				    b_offset == 0 && page_offset == 0 &&
1154 				    clen == STRIPE_SIZE &&
1155 				    !no_skipcopy)
1156 					*page = bio_page;
1157 				else
1158 					tx = async_memcpy(*page, bio_page, page_offset,
1159 						  b_offset, clen, &submit);
1160 			} else
1161 				tx = async_memcpy(bio_page, *page, b_offset,
1162 						  page_offset, clen, &submit);
1163 		}
1164 		/* chain the operations */
1165 		submit.depend_tx = tx;
1166 
1167 		if (clen < len) /* hit end of page */
1168 			break;
1169 		page_offset +=  len;
1170 	}
1171 
1172 	return tx;
1173 }
1174 
1175 static void ops_complete_biofill(void *stripe_head_ref)
1176 {
1177 	struct stripe_head *sh = stripe_head_ref;
1178 	struct bio_list return_bi = BIO_EMPTY_LIST;
1179 	int i;
1180 
1181 	pr_debug("%s: stripe %llu\n", __func__,
1182 		(unsigned long long)sh->sector);
1183 
1184 	/* clear completed biofills */
1185 	for (i = sh->disks; i--; ) {
1186 		struct r5dev *dev = &sh->dev[i];
1187 
1188 		/* acknowledge completion of a biofill operation */
1189 		/* and check if we need to reply to a read request,
1190 		 * new R5_Wantfill requests are held off until
1191 		 * !STRIPE_BIOFILL_RUN
1192 		 */
1193 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1194 			struct bio *rbi, *rbi2;
1195 
1196 			BUG_ON(!dev->read);
1197 			rbi = dev->read;
1198 			dev->read = NULL;
1199 			while (rbi && rbi->bi_iter.bi_sector <
1200 				dev->sector + STRIPE_SECTORS) {
1201 				rbi2 = r5_next_bio(rbi, dev->sector);
1202 				if (!raid5_dec_bi_active_stripes(rbi))
1203 					bio_list_add(&return_bi, rbi);
1204 				rbi = rbi2;
1205 			}
1206 		}
1207 	}
1208 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1209 
1210 	return_io(&return_bi);
1211 
1212 	set_bit(STRIPE_HANDLE, &sh->state);
1213 	raid5_release_stripe(sh);
1214 }
1215 
1216 static void ops_run_biofill(struct stripe_head *sh)
1217 {
1218 	struct dma_async_tx_descriptor *tx = NULL;
1219 	struct async_submit_ctl submit;
1220 	int i;
1221 
1222 	BUG_ON(sh->batch_head);
1223 	pr_debug("%s: stripe %llu\n", __func__,
1224 		(unsigned long long)sh->sector);
1225 
1226 	for (i = sh->disks; i--; ) {
1227 		struct r5dev *dev = &sh->dev[i];
1228 		if (test_bit(R5_Wantfill, &dev->flags)) {
1229 			struct bio *rbi;
1230 			spin_lock_irq(&sh->stripe_lock);
1231 			dev->read = rbi = dev->toread;
1232 			dev->toread = NULL;
1233 			spin_unlock_irq(&sh->stripe_lock);
1234 			while (rbi && rbi->bi_iter.bi_sector <
1235 				dev->sector + STRIPE_SECTORS) {
1236 				tx = async_copy_data(0, rbi, &dev->page,
1237 						     dev->sector, tx, sh, 0);
1238 				rbi = r5_next_bio(rbi, dev->sector);
1239 			}
1240 		}
1241 	}
1242 
1243 	atomic_inc(&sh->count);
1244 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1245 	async_trigger_callback(&submit);
1246 }
1247 
1248 static void mark_target_uptodate(struct stripe_head *sh, int target)
1249 {
1250 	struct r5dev *tgt;
1251 
1252 	if (target < 0)
1253 		return;
1254 
1255 	tgt = &sh->dev[target];
1256 	set_bit(R5_UPTODATE, &tgt->flags);
1257 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1258 	clear_bit(R5_Wantcompute, &tgt->flags);
1259 }
1260 
1261 static void ops_complete_compute(void *stripe_head_ref)
1262 {
1263 	struct stripe_head *sh = stripe_head_ref;
1264 
1265 	pr_debug("%s: stripe %llu\n", __func__,
1266 		(unsigned long long)sh->sector);
1267 
1268 	/* mark the computed target(s) as uptodate */
1269 	mark_target_uptodate(sh, sh->ops.target);
1270 	mark_target_uptodate(sh, sh->ops.target2);
1271 
1272 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1273 	if (sh->check_state == check_state_compute_run)
1274 		sh->check_state = check_state_compute_result;
1275 	set_bit(STRIPE_HANDLE, &sh->state);
1276 	raid5_release_stripe(sh);
1277 }
1278 
1279 /* return a pointer to the address conversion region of the scribble buffer */
1280 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1281 				 struct raid5_percpu *percpu, int i)
1282 {
1283 	void *addr;
1284 
1285 	addr = flex_array_get(percpu->scribble, i);
1286 	return addr + sizeof(struct page *) * (sh->disks + 2);
1287 }
1288 
1289 /* return a pointer to the address conversion region of the scribble buffer */
1290 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1291 {
1292 	void *addr;
1293 
1294 	addr = flex_array_get(percpu->scribble, i);
1295 	return addr;
1296 }
1297 
1298 static struct dma_async_tx_descriptor *
1299 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1300 {
1301 	int disks = sh->disks;
1302 	struct page **xor_srcs = to_addr_page(percpu, 0);
1303 	int target = sh->ops.target;
1304 	struct r5dev *tgt = &sh->dev[target];
1305 	struct page *xor_dest = tgt->page;
1306 	int count = 0;
1307 	struct dma_async_tx_descriptor *tx;
1308 	struct async_submit_ctl submit;
1309 	int i;
1310 
1311 	BUG_ON(sh->batch_head);
1312 
1313 	pr_debug("%s: stripe %llu block: %d\n",
1314 		__func__, (unsigned long long)sh->sector, target);
1315 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1316 
1317 	for (i = disks; i--; )
1318 		if (i != target)
1319 			xor_srcs[count++] = sh->dev[i].page;
1320 
1321 	atomic_inc(&sh->count);
1322 
1323 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1324 			  ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1325 	if (unlikely(count == 1))
1326 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1327 	else
1328 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1329 
1330 	return tx;
1331 }
1332 
1333 /* set_syndrome_sources - populate source buffers for gen_syndrome
1334  * @srcs - (struct page *) array of size sh->disks
1335  * @sh - stripe_head to parse
1336  *
1337  * Populates srcs in proper layout order for the stripe and returns the
1338  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1339  * destination buffer is recorded in srcs[count] and the Q destination
1340  * is recorded in srcs[count+1]].
1341  */
1342 static int set_syndrome_sources(struct page **srcs,
1343 				struct stripe_head *sh,
1344 				int srctype)
1345 {
1346 	int disks = sh->disks;
1347 	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1348 	int d0_idx = raid6_d0(sh);
1349 	int count;
1350 	int i;
1351 
1352 	for (i = 0; i < disks; i++)
1353 		srcs[i] = NULL;
1354 
1355 	count = 0;
1356 	i = d0_idx;
1357 	do {
1358 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1359 		struct r5dev *dev = &sh->dev[i];
1360 
1361 		if (i == sh->qd_idx || i == sh->pd_idx ||
1362 		    (srctype == SYNDROME_SRC_ALL) ||
1363 		    (srctype == SYNDROME_SRC_WANT_DRAIN &&
1364 		     (test_bit(R5_Wantdrain, &dev->flags) ||
1365 		      test_bit(R5_InJournal, &dev->flags))) ||
1366 		    (srctype == SYNDROME_SRC_WRITTEN &&
1367 		     dev->written)) {
1368 			if (test_bit(R5_InJournal, &dev->flags))
1369 				srcs[slot] = sh->dev[i].orig_page;
1370 			else
1371 				srcs[slot] = sh->dev[i].page;
1372 		}
1373 		i = raid6_next_disk(i, disks);
1374 	} while (i != d0_idx);
1375 
1376 	return syndrome_disks;
1377 }
1378 
1379 static struct dma_async_tx_descriptor *
1380 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1381 {
1382 	int disks = sh->disks;
1383 	struct page **blocks = to_addr_page(percpu, 0);
1384 	int target;
1385 	int qd_idx = sh->qd_idx;
1386 	struct dma_async_tx_descriptor *tx;
1387 	struct async_submit_ctl submit;
1388 	struct r5dev *tgt;
1389 	struct page *dest;
1390 	int i;
1391 	int count;
1392 
1393 	BUG_ON(sh->batch_head);
1394 	if (sh->ops.target < 0)
1395 		target = sh->ops.target2;
1396 	else if (sh->ops.target2 < 0)
1397 		target = sh->ops.target;
1398 	else
1399 		/* we should only have one valid target */
1400 		BUG();
1401 	BUG_ON(target < 0);
1402 	pr_debug("%s: stripe %llu block: %d\n",
1403 		__func__, (unsigned long long)sh->sector, target);
1404 
1405 	tgt = &sh->dev[target];
1406 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1407 	dest = tgt->page;
1408 
1409 	atomic_inc(&sh->count);
1410 
1411 	if (target == qd_idx) {
1412 		count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1413 		blocks[count] = NULL; /* regenerating p is not necessary */
1414 		BUG_ON(blocks[count+1] != dest); /* q should already be set */
1415 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1416 				  ops_complete_compute, sh,
1417 				  to_addr_conv(sh, percpu, 0));
1418 		tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1419 	} else {
1420 		/* Compute any data- or p-drive using XOR */
1421 		count = 0;
1422 		for (i = disks; i-- ; ) {
1423 			if (i == target || i == qd_idx)
1424 				continue;
1425 			blocks[count++] = sh->dev[i].page;
1426 		}
1427 
1428 		init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1429 				  NULL, ops_complete_compute, sh,
1430 				  to_addr_conv(sh, percpu, 0));
1431 		tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1432 	}
1433 
1434 	return tx;
1435 }
1436 
1437 static struct dma_async_tx_descriptor *
1438 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1439 {
1440 	int i, count, disks = sh->disks;
1441 	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1442 	int d0_idx = raid6_d0(sh);
1443 	int faila = -1, failb = -1;
1444 	int target = sh->ops.target;
1445 	int target2 = sh->ops.target2;
1446 	struct r5dev *tgt = &sh->dev[target];
1447 	struct r5dev *tgt2 = &sh->dev[target2];
1448 	struct dma_async_tx_descriptor *tx;
1449 	struct page **blocks = to_addr_page(percpu, 0);
1450 	struct async_submit_ctl submit;
1451 
1452 	BUG_ON(sh->batch_head);
1453 	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1454 		 __func__, (unsigned long long)sh->sector, target, target2);
1455 	BUG_ON(target < 0 || target2 < 0);
1456 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1457 	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1458 
1459 	/* we need to open-code set_syndrome_sources to handle the
1460 	 * slot number conversion for 'faila' and 'failb'
1461 	 */
1462 	for (i = 0; i < disks ; i++)
1463 		blocks[i] = NULL;
1464 	count = 0;
1465 	i = d0_idx;
1466 	do {
1467 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1468 
1469 		blocks[slot] = sh->dev[i].page;
1470 
1471 		if (i == target)
1472 			faila = slot;
1473 		if (i == target2)
1474 			failb = slot;
1475 		i = raid6_next_disk(i, disks);
1476 	} while (i != d0_idx);
1477 
1478 	BUG_ON(faila == failb);
1479 	if (failb < faila)
1480 		swap(faila, failb);
1481 	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1482 		 __func__, (unsigned long long)sh->sector, faila, failb);
1483 
1484 	atomic_inc(&sh->count);
1485 
1486 	if (failb == syndrome_disks+1) {
1487 		/* Q disk is one of the missing disks */
1488 		if (faila == syndrome_disks) {
1489 			/* Missing P+Q, just recompute */
1490 			init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1491 					  ops_complete_compute, sh,
1492 					  to_addr_conv(sh, percpu, 0));
1493 			return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1494 						  STRIPE_SIZE, &submit);
1495 		} else {
1496 			struct page *dest;
1497 			int data_target;
1498 			int qd_idx = sh->qd_idx;
1499 
1500 			/* Missing D+Q: recompute D from P, then recompute Q */
1501 			if (target == qd_idx)
1502 				data_target = target2;
1503 			else
1504 				data_target = target;
1505 
1506 			count = 0;
1507 			for (i = disks; i-- ; ) {
1508 				if (i == data_target || i == qd_idx)
1509 					continue;
1510 				blocks[count++] = sh->dev[i].page;
1511 			}
1512 			dest = sh->dev[data_target].page;
1513 			init_async_submit(&submit,
1514 					  ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1515 					  NULL, NULL, NULL,
1516 					  to_addr_conv(sh, percpu, 0));
1517 			tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1518 				       &submit);
1519 
1520 			count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1521 			init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1522 					  ops_complete_compute, sh,
1523 					  to_addr_conv(sh, percpu, 0));
1524 			return async_gen_syndrome(blocks, 0, count+2,
1525 						  STRIPE_SIZE, &submit);
1526 		}
1527 	} else {
1528 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1529 				  ops_complete_compute, sh,
1530 				  to_addr_conv(sh, percpu, 0));
1531 		if (failb == syndrome_disks) {
1532 			/* We're missing D+P. */
1533 			return async_raid6_datap_recov(syndrome_disks+2,
1534 						       STRIPE_SIZE, faila,
1535 						       blocks, &submit);
1536 		} else {
1537 			/* We're missing D+D. */
1538 			return async_raid6_2data_recov(syndrome_disks+2,
1539 						       STRIPE_SIZE, faila, failb,
1540 						       blocks, &submit);
1541 		}
1542 	}
1543 }
1544 
1545 static void ops_complete_prexor(void *stripe_head_ref)
1546 {
1547 	struct stripe_head *sh = stripe_head_ref;
1548 
1549 	pr_debug("%s: stripe %llu\n", __func__,
1550 		(unsigned long long)sh->sector);
1551 
1552 	if (r5c_is_writeback(sh->raid_conf->log))
1553 		/*
1554 		 * raid5-cache write back uses orig_page during prexor.
1555 		 * After prexor, it is time to free orig_page
1556 		 */
1557 		r5c_release_extra_page(sh);
1558 }
1559 
1560 static struct dma_async_tx_descriptor *
1561 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1562 		struct dma_async_tx_descriptor *tx)
1563 {
1564 	int disks = sh->disks;
1565 	struct page **xor_srcs = to_addr_page(percpu, 0);
1566 	int count = 0, pd_idx = sh->pd_idx, i;
1567 	struct async_submit_ctl submit;
1568 
1569 	/* existing parity data subtracted */
1570 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1571 
1572 	BUG_ON(sh->batch_head);
1573 	pr_debug("%s: stripe %llu\n", __func__,
1574 		(unsigned long long)sh->sector);
1575 
1576 	for (i = disks; i--; ) {
1577 		struct r5dev *dev = &sh->dev[i];
1578 		/* Only process blocks that are known to be uptodate */
1579 		if (test_bit(R5_InJournal, &dev->flags))
1580 			xor_srcs[count++] = dev->orig_page;
1581 		else if (test_bit(R5_Wantdrain, &dev->flags))
1582 			xor_srcs[count++] = dev->page;
1583 	}
1584 
1585 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1586 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1587 	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1588 
1589 	return tx;
1590 }
1591 
1592 static struct dma_async_tx_descriptor *
1593 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1594 		struct dma_async_tx_descriptor *tx)
1595 {
1596 	struct page **blocks = to_addr_page(percpu, 0);
1597 	int count;
1598 	struct async_submit_ctl submit;
1599 
1600 	pr_debug("%s: stripe %llu\n", __func__,
1601 		(unsigned long long)sh->sector);
1602 
1603 	count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1604 
1605 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1606 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1607 	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1608 
1609 	return tx;
1610 }
1611 
1612 static struct dma_async_tx_descriptor *
1613 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1614 {
1615 	struct r5conf *conf = sh->raid_conf;
1616 	int disks = sh->disks;
1617 	int i;
1618 	struct stripe_head *head_sh = sh;
1619 
1620 	pr_debug("%s: stripe %llu\n", __func__,
1621 		(unsigned long long)sh->sector);
1622 
1623 	for (i = disks; i--; ) {
1624 		struct r5dev *dev;
1625 		struct bio *chosen;
1626 
1627 		sh = head_sh;
1628 		if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1629 			struct bio *wbi;
1630 
1631 again:
1632 			dev = &sh->dev[i];
1633 			/*
1634 			 * clear R5_InJournal, so when rewriting a page in
1635 			 * journal, it is not skipped by r5l_log_stripe()
1636 			 */
1637 			clear_bit(R5_InJournal, &dev->flags);
1638 			spin_lock_irq(&sh->stripe_lock);
1639 			chosen = dev->towrite;
1640 			dev->towrite = NULL;
1641 			sh->overwrite_disks = 0;
1642 			BUG_ON(dev->written);
1643 			wbi = dev->written = chosen;
1644 			spin_unlock_irq(&sh->stripe_lock);
1645 			WARN_ON(dev->page != dev->orig_page);
1646 
1647 			while (wbi && wbi->bi_iter.bi_sector <
1648 				dev->sector + STRIPE_SECTORS) {
1649 				if (wbi->bi_opf & REQ_FUA)
1650 					set_bit(R5_WantFUA, &dev->flags);
1651 				if (wbi->bi_opf & REQ_SYNC)
1652 					set_bit(R5_SyncIO, &dev->flags);
1653 				if (bio_op(wbi) == REQ_OP_DISCARD)
1654 					set_bit(R5_Discard, &dev->flags);
1655 				else {
1656 					tx = async_copy_data(1, wbi, &dev->page,
1657 							     dev->sector, tx, sh,
1658 							     r5c_is_writeback(conf->log));
1659 					if (dev->page != dev->orig_page &&
1660 					    !r5c_is_writeback(conf->log)) {
1661 						set_bit(R5_SkipCopy, &dev->flags);
1662 						clear_bit(R5_UPTODATE, &dev->flags);
1663 						clear_bit(R5_OVERWRITE, &dev->flags);
1664 					}
1665 				}
1666 				wbi = r5_next_bio(wbi, dev->sector);
1667 			}
1668 
1669 			if (head_sh->batch_head) {
1670 				sh = list_first_entry(&sh->batch_list,
1671 						      struct stripe_head,
1672 						      batch_list);
1673 				if (sh == head_sh)
1674 					continue;
1675 				goto again;
1676 			}
1677 		}
1678 	}
1679 
1680 	return tx;
1681 }
1682 
1683 static void ops_complete_reconstruct(void *stripe_head_ref)
1684 {
1685 	struct stripe_head *sh = stripe_head_ref;
1686 	int disks = sh->disks;
1687 	int pd_idx = sh->pd_idx;
1688 	int qd_idx = sh->qd_idx;
1689 	int i;
1690 	bool fua = false, sync = false, discard = false;
1691 
1692 	pr_debug("%s: stripe %llu\n", __func__,
1693 		(unsigned long long)sh->sector);
1694 
1695 	for (i = disks; i--; ) {
1696 		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1697 		sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1698 		discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1699 	}
1700 
1701 	for (i = disks; i--; ) {
1702 		struct r5dev *dev = &sh->dev[i];
1703 
1704 		if (dev->written || i == pd_idx || i == qd_idx) {
1705 			if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1706 				set_bit(R5_UPTODATE, &dev->flags);
1707 			if (fua)
1708 				set_bit(R5_WantFUA, &dev->flags);
1709 			if (sync)
1710 				set_bit(R5_SyncIO, &dev->flags);
1711 		}
1712 	}
1713 
1714 	if (sh->reconstruct_state == reconstruct_state_drain_run)
1715 		sh->reconstruct_state = reconstruct_state_drain_result;
1716 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1717 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1718 	else {
1719 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1720 		sh->reconstruct_state = reconstruct_state_result;
1721 	}
1722 
1723 	set_bit(STRIPE_HANDLE, &sh->state);
1724 	raid5_release_stripe(sh);
1725 }
1726 
1727 static void
1728 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1729 		     struct dma_async_tx_descriptor *tx)
1730 {
1731 	int disks = sh->disks;
1732 	struct page **xor_srcs;
1733 	struct async_submit_ctl submit;
1734 	int count, pd_idx = sh->pd_idx, i;
1735 	struct page *xor_dest;
1736 	int prexor = 0;
1737 	unsigned long flags;
1738 	int j = 0;
1739 	struct stripe_head *head_sh = sh;
1740 	int last_stripe;
1741 
1742 	pr_debug("%s: stripe %llu\n", __func__,
1743 		(unsigned long long)sh->sector);
1744 
1745 	for (i = 0; i < sh->disks; i++) {
1746 		if (pd_idx == i)
1747 			continue;
1748 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1749 			break;
1750 	}
1751 	if (i >= sh->disks) {
1752 		atomic_inc(&sh->count);
1753 		set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1754 		ops_complete_reconstruct(sh);
1755 		return;
1756 	}
1757 again:
1758 	count = 0;
1759 	xor_srcs = to_addr_page(percpu, j);
1760 	/* check if prexor is active which means only process blocks
1761 	 * that are part of a read-modify-write (written)
1762 	 */
1763 	if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1764 		prexor = 1;
1765 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1766 		for (i = disks; i--; ) {
1767 			struct r5dev *dev = &sh->dev[i];
1768 			if (head_sh->dev[i].written ||
1769 			    test_bit(R5_InJournal, &head_sh->dev[i].flags))
1770 				xor_srcs[count++] = dev->page;
1771 		}
1772 	} else {
1773 		xor_dest = sh->dev[pd_idx].page;
1774 		for (i = disks; i--; ) {
1775 			struct r5dev *dev = &sh->dev[i];
1776 			if (i != pd_idx)
1777 				xor_srcs[count++] = dev->page;
1778 		}
1779 	}
1780 
1781 	/* 1/ if we prexor'd then the dest is reused as a source
1782 	 * 2/ if we did not prexor then we are redoing the parity
1783 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1784 	 * for the synchronous xor case
1785 	 */
1786 	last_stripe = !head_sh->batch_head ||
1787 		list_first_entry(&sh->batch_list,
1788 				 struct stripe_head, batch_list) == head_sh;
1789 	if (last_stripe) {
1790 		flags = ASYNC_TX_ACK |
1791 			(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1792 
1793 		atomic_inc(&head_sh->count);
1794 		init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1795 				  to_addr_conv(sh, percpu, j));
1796 	} else {
1797 		flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1798 		init_async_submit(&submit, flags, tx, NULL, NULL,
1799 				  to_addr_conv(sh, percpu, j));
1800 	}
1801 
1802 	if (unlikely(count == 1))
1803 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1804 	else
1805 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1806 	if (!last_stripe) {
1807 		j++;
1808 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1809 				      batch_list);
1810 		goto again;
1811 	}
1812 }
1813 
1814 static void
1815 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1816 		     struct dma_async_tx_descriptor *tx)
1817 {
1818 	struct async_submit_ctl submit;
1819 	struct page **blocks;
1820 	int count, i, j = 0;
1821 	struct stripe_head *head_sh = sh;
1822 	int last_stripe;
1823 	int synflags;
1824 	unsigned long txflags;
1825 
1826 	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1827 
1828 	for (i = 0; i < sh->disks; i++) {
1829 		if (sh->pd_idx == i || sh->qd_idx == i)
1830 			continue;
1831 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1832 			break;
1833 	}
1834 	if (i >= sh->disks) {
1835 		atomic_inc(&sh->count);
1836 		set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1837 		set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1838 		ops_complete_reconstruct(sh);
1839 		return;
1840 	}
1841 
1842 again:
1843 	blocks = to_addr_page(percpu, j);
1844 
1845 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1846 		synflags = SYNDROME_SRC_WRITTEN;
1847 		txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1848 	} else {
1849 		synflags = SYNDROME_SRC_ALL;
1850 		txflags = ASYNC_TX_ACK;
1851 	}
1852 
1853 	count = set_syndrome_sources(blocks, sh, synflags);
1854 	last_stripe = !head_sh->batch_head ||
1855 		list_first_entry(&sh->batch_list,
1856 				 struct stripe_head, batch_list) == head_sh;
1857 
1858 	if (last_stripe) {
1859 		atomic_inc(&head_sh->count);
1860 		init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1861 				  head_sh, to_addr_conv(sh, percpu, j));
1862 	} else
1863 		init_async_submit(&submit, 0, tx, NULL, NULL,
1864 				  to_addr_conv(sh, percpu, j));
1865 	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1866 	if (!last_stripe) {
1867 		j++;
1868 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1869 				      batch_list);
1870 		goto again;
1871 	}
1872 }
1873 
1874 static void ops_complete_check(void *stripe_head_ref)
1875 {
1876 	struct stripe_head *sh = stripe_head_ref;
1877 
1878 	pr_debug("%s: stripe %llu\n", __func__,
1879 		(unsigned long long)sh->sector);
1880 
1881 	sh->check_state = check_state_check_result;
1882 	set_bit(STRIPE_HANDLE, &sh->state);
1883 	raid5_release_stripe(sh);
1884 }
1885 
1886 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1887 {
1888 	int disks = sh->disks;
1889 	int pd_idx = sh->pd_idx;
1890 	int qd_idx = sh->qd_idx;
1891 	struct page *xor_dest;
1892 	struct page **xor_srcs = to_addr_page(percpu, 0);
1893 	struct dma_async_tx_descriptor *tx;
1894 	struct async_submit_ctl submit;
1895 	int count;
1896 	int i;
1897 
1898 	pr_debug("%s: stripe %llu\n", __func__,
1899 		(unsigned long long)sh->sector);
1900 
1901 	BUG_ON(sh->batch_head);
1902 	count = 0;
1903 	xor_dest = sh->dev[pd_idx].page;
1904 	xor_srcs[count++] = xor_dest;
1905 	for (i = disks; i--; ) {
1906 		if (i == pd_idx || i == qd_idx)
1907 			continue;
1908 		xor_srcs[count++] = sh->dev[i].page;
1909 	}
1910 
1911 	init_async_submit(&submit, 0, NULL, NULL, NULL,
1912 			  to_addr_conv(sh, percpu, 0));
1913 	tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1914 			   &sh->ops.zero_sum_result, &submit);
1915 
1916 	atomic_inc(&sh->count);
1917 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1918 	tx = async_trigger_callback(&submit);
1919 }
1920 
1921 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1922 {
1923 	struct page **srcs = to_addr_page(percpu, 0);
1924 	struct async_submit_ctl submit;
1925 	int count;
1926 
1927 	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1928 		(unsigned long long)sh->sector, checkp);
1929 
1930 	BUG_ON(sh->batch_head);
1931 	count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
1932 	if (!checkp)
1933 		srcs[count] = NULL;
1934 
1935 	atomic_inc(&sh->count);
1936 	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1937 			  sh, to_addr_conv(sh, percpu, 0));
1938 	async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1939 			   &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1940 }
1941 
1942 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1943 {
1944 	int overlap_clear = 0, i, disks = sh->disks;
1945 	struct dma_async_tx_descriptor *tx = NULL;
1946 	struct r5conf *conf = sh->raid_conf;
1947 	int level = conf->level;
1948 	struct raid5_percpu *percpu;
1949 	unsigned long cpu;
1950 
1951 	cpu = get_cpu();
1952 	percpu = per_cpu_ptr(conf->percpu, cpu);
1953 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1954 		ops_run_biofill(sh);
1955 		overlap_clear++;
1956 	}
1957 
1958 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1959 		if (level < 6)
1960 			tx = ops_run_compute5(sh, percpu);
1961 		else {
1962 			if (sh->ops.target2 < 0 || sh->ops.target < 0)
1963 				tx = ops_run_compute6_1(sh, percpu);
1964 			else
1965 				tx = ops_run_compute6_2(sh, percpu);
1966 		}
1967 		/* terminate the chain if reconstruct is not set to be run */
1968 		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1969 			async_tx_ack(tx);
1970 	}
1971 
1972 	if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
1973 		if (level < 6)
1974 			tx = ops_run_prexor5(sh, percpu, tx);
1975 		else
1976 			tx = ops_run_prexor6(sh, percpu, tx);
1977 	}
1978 
1979 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1980 		tx = ops_run_biodrain(sh, tx);
1981 		overlap_clear++;
1982 	}
1983 
1984 	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1985 		if (level < 6)
1986 			ops_run_reconstruct5(sh, percpu, tx);
1987 		else
1988 			ops_run_reconstruct6(sh, percpu, tx);
1989 	}
1990 
1991 	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1992 		if (sh->check_state == check_state_run)
1993 			ops_run_check_p(sh, percpu);
1994 		else if (sh->check_state == check_state_run_q)
1995 			ops_run_check_pq(sh, percpu, 0);
1996 		else if (sh->check_state == check_state_run_pq)
1997 			ops_run_check_pq(sh, percpu, 1);
1998 		else
1999 			BUG();
2000 	}
2001 
2002 	if (overlap_clear && !sh->batch_head)
2003 		for (i = disks; i--; ) {
2004 			struct r5dev *dev = &sh->dev[i];
2005 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
2006 				wake_up(&sh->raid_conf->wait_for_overlap);
2007 		}
2008 	put_cpu();
2009 }
2010 
2011 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
2012 	int disks)
2013 {
2014 	struct stripe_head *sh;
2015 	int i;
2016 
2017 	sh = kmem_cache_zalloc(sc, gfp);
2018 	if (sh) {
2019 		spin_lock_init(&sh->stripe_lock);
2020 		spin_lock_init(&sh->batch_lock);
2021 		INIT_LIST_HEAD(&sh->batch_list);
2022 		INIT_LIST_HEAD(&sh->lru);
2023 		INIT_LIST_HEAD(&sh->r5c);
2024 		INIT_LIST_HEAD(&sh->log_list);
2025 		atomic_set(&sh->count, 1);
2026 		sh->log_start = MaxSector;
2027 		for (i = 0; i < disks; i++) {
2028 			struct r5dev *dev = &sh->dev[i];
2029 
2030 			bio_init(&dev->req, &dev->vec, 1);
2031 			bio_init(&dev->rreq, &dev->rvec, 1);
2032 		}
2033 	}
2034 	return sh;
2035 }
2036 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2037 {
2038 	struct stripe_head *sh;
2039 
2040 	sh = alloc_stripe(conf->slab_cache, gfp, conf->pool_size);
2041 	if (!sh)
2042 		return 0;
2043 
2044 	sh->raid_conf = conf;
2045 
2046 	if (grow_buffers(sh, gfp)) {
2047 		shrink_buffers(sh);
2048 		kmem_cache_free(conf->slab_cache, sh);
2049 		return 0;
2050 	}
2051 	sh->hash_lock_index =
2052 		conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2053 	/* we just created an active stripe so... */
2054 	atomic_inc(&conf->active_stripes);
2055 
2056 	raid5_release_stripe(sh);
2057 	conf->max_nr_stripes++;
2058 	return 1;
2059 }
2060 
2061 static int grow_stripes(struct r5conf *conf, int num)
2062 {
2063 	struct kmem_cache *sc;
2064 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
2065 
2066 	if (conf->mddev->gendisk)
2067 		sprintf(conf->cache_name[0],
2068 			"raid%d-%s", conf->level, mdname(conf->mddev));
2069 	else
2070 		sprintf(conf->cache_name[0],
2071 			"raid%d-%p", conf->level, conf->mddev);
2072 	sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
2073 
2074 	conf->active_name = 0;
2075 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
2076 			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2077 			       0, 0, NULL);
2078 	if (!sc)
2079 		return 1;
2080 	conf->slab_cache = sc;
2081 	conf->pool_size = devs;
2082 	while (num--)
2083 		if (!grow_one_stripe(conf, GFP_KERNEL))
2084 			return 1;
2085 
2086 	return 0;
2087 }
2088 
2089 /**
2090  * scribble_len - return the required size of the scribble region
2091  * @num - total number of disks in the array
2092  *
2093  * The size must be enough to contain:
2094  * 1/ a struct page pointer for each device in the array +2
2095  * 2/ room to convert each entry in (1) to its corresponding dma
2096  *    (dma_map_page()) or page (page_address()) address.
2097  *
2098  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2099  * calculate over all devices (not just the data blocks), using zeros in place
2100  * of the P and Q blocks.
2101  */
2102 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2103 {
2104 	struct flex_array *ret;
2105 	size_t len;
2106 
2107 	len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2108 	ret = flex_array_alloc(len, cnt, flags);
2109 	if (!ret)
2110 		return NULL;
2111 	/* always prealloc all elements, so no locking is required */
2112 	if (flex_array_prealloc(ret, 0, cnt, flags)) {
2113 		flex_array_free(ret);
2114 		return NULL;
2115 	}
2116 	return ret;
2117 }
2118 
2119 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2120 {
2121 	unsigned long cpu;
2122 	int err = 0;
2123 
2124 	/*
2125 	 * Never shrink. And mddev_suspend() could deadlock if this is called
2126 	 * from raid5d. In that case, scribble_disks and scribble_sectors
2127 	 * should equal to new_disks and new_sectors
2128 	 */
2129 	if (conf->scribble_disks >= new_disks &&
2130 	    conf->scribble_sectors >= new_sectors)
2131 		return 0;
2132 	mddev_suspend(conf->mddev);
2133 	get_online_cpus();
2134 	for_each_present_cpu(cpu) {
2135 		struct raid5_percpu *percpu;
2136 		struct flex_array *scribble;
2137 
2138 		percpu = per_cpu_ptr(conf->percpu, cpu);
2139 		scribble = scribble_alloc(new_disks,
2140 					  new_sectors / STRIPE_SECTORS,
2141 					  GFP_NOIO);
2142 
2143 		if (scribble) {
2144 			flex_array_free(percpu->scribble);
2145 			percpu->scribble = scribble;
2146 		} else {
2147 			err = -ENOMEM;
2148 			break;
2149 		}
2150 	}
2151 	put_online_cpus();
2152 	mddev_resume(conf->mddev);
2153 	if (!err) {
2154 		conf->scribble_disks = new_disks;
2155 		conf->scribble_sectors = new_sectors;
2156 	}
2157 	return err;
2158 }
2159 
2160 static int resize_stripes(struct r5conf *conf, int newsize)
2161 {
2162 	/* Make all the stripes able to hold 'newsize' devices.
2163 	 * New slots in each stripe get 'page' set to a new page.
2164 	 *
2165 	 * This happens in stages:
2166 	 * 1/ create a new kmem_cache and allocate the required number of
2167 	 *    stripe_heads.
2168 	 * 2/ gather all the old stripe_heads and transfer the pages across
2169 	 *    to the new stripe_heads.  This will have the side effect of
2170 	 *    freezing the array as once all stripe_heads have been collected,
2171 	 *    no IO will be possible.  Old stripe heads are freed once their
2172 	 *    pages have been transferred over, and the old kmem_cache is
2173 	 *    freed when all stripes are done.
2174 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2175 	 *    we simple return a failre status - no need to clean anything up.
2176 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
2177 	 *    If this fails, we don't bother trying the shrink the
2178 	 *    stripe_heads down again, we just leave them as they are.
2179 	 *    As each stripe_head is processed the new one is released into
2180 	 *    active service.
2181 	 *
2182 	 * Once step2 is started, we cannot afford to wait for a write,
2183 	 * so we use GFP_NOIO allocations.
2184 	 */
2185 	struct stripe_head *osh, *nsh;
2186 	LIST_HEAD(newstripes);
2187 	struct disk_info *ndisks;
2188 	int err;
2189 	struct kmem_cache *sc;
2190 	int i;
2191 	int hash, cnt;
2192 
2193 	if (newsize <= conf->pool_size)
2194 		return 0; /* never bother to shrink */
2195 
2196 	err = md_allow_write(conf->mddev);
2197 	if (err)
2198 		return err;
2199 
2200 	/* Step 1 */
2201 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2202 			       sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2203 			       0, 0, NULL);
2204 	if (!sc)
2205 		return -ENOMEM;
2206 
2207 	/* Need to ensure auto-resizing doesn't interfere */
2208 	mutex_lock(&conf->cache_size_mutex);
2209 
2210 	for (i = conf->max_nr_stripes; i; i--) {
2211 		nsh = alloc_stripe(sc, GFP_KERNEL, newsize);
2212 		if (!nsh)
2213 			break;
2214 
2215 		nsh->raid_conf = conf;
2216 		list_add(&nsh->lru, &newstripes);
2217 	}
2218 	if (i) {
2219 		/* didn't get enough, give up */
2220 		while (!list_empty(&newstripes)) {
2221 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
2222 			list_del(&nsh->lru);
2223 			kmem_cache_free(sc, nsh);
2224 		}
2225 		kmem_cache_destroy(sc);
2226 		mutex_unlock(&conf->cache_size_mutex);
2227 		return -ENOMEM;
2228 	}
2229 	/* Step 2 - Must use GFP_NOIO now.
2230 	 * OK, we have enough stripes, start collecting inactive
2231 	 * stripes and copying them over
2232 	 */
2233 	hash = 0;
2234 	cnt = 0;
2235 	list_for_each_entry(nsh, &newstripes, lru) {
2236 		lock_device_hash_lock(conf, hash);
2237 		wait_event_cmd(conf->wait_for_stripe,
2238 				    !list_empty(conf->inactive_list + hash),
2239 				    unlock_device_hash_lock(conf, hash),
2240 				    lock_device_hash_lock(conf, hash));
2241 		osh = get_free_stripe(conf, hash);
2242 		unlock_device_hash_lock(conf, hash);
2243 
2244 		for(i=0; i<conf->pool_size; i++) {
2245 			nsh->dev[i].page = osh->dev[i].page;
2246 			nsh->dev[i].orig_page = osh->dev[i].page;
2247 		}
2248 		nsh->hash_lock_index = hash;
2249 		kmem_cache_free(conf->slab_cache, osh);
2250 		cnt++;
2251 		if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2252 		    !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2253 			hash++;
2254 			cnt = 0;
2255 		}
2256 	}
2257 	kmem_cache_destroy(conf->slab_cache);
2258 
2259 	/* Step 3.
2260 	 * At this point, we are holding all the stripes so the array
2261 	 * is completely stalled, so now is a good time to resize
2262 	 * conf->disks and the scribble region
2263 	 */
2264 	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2265 	if (ndisks) {
2266 		for (i = 0; i < conf->pool_size; i++)
2267 			ndisks[i] = conf->disks[i];
2268 
2269 		for (i = conf->pool_size; i < newsize; i++) {
2270 			ndisks[i].extra_page = alloc_page(GFP_NOIO);
2271 			if (!ndisks[i].extra_page)
2272 				err = -ENOMEM;
2273 		}
2274 
2275 		if (err) {
2276 			for (i = conf->pool_size; i < newsize; i++)
2277 				if (ndisks[i].extra_page)
2278 					put_page(ndisks[i].extra_page);
2279 			kfree(ndisks);
2280 		} else {
2281 			kfree(conf->disks);
2282 			conf->disks = ndisks;
2283 		}
2284 	} else
2285 		err = -ENOMEM;
2286 
2287 	mutex_unlock(&conf->cache_size_mutex);
2288 	/* Step 4, return new stripes to service */
2289 	while(!list_empty(&newstripes)) {
2290 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
2291 		list_del_init(&nsh->lru);
2292 
2293 		for (i=conf->raid_disks; i < newsize; i++)
2294 			if (nsh->dev[i].page == NULL) {
2295 				struct page *p = alloc_page(GFP_NOIO);
2296 				nsh->dev[i].page = p;
2297 				nsh->dev[i].orig_page = p;
2298 				if (!p)
2299 					err = -ENOMEM;
2300 			}
2301 		raid5_release_stripe(nsh);
2302 	}
2303 	/* critical section pass, GFP_NOIO no longer needed */
2304 
2305 	conf->slab_cache = sc;
2306 	conf->active_name = 1-conf->active_name;
2307 	if (!err)
2308 		conf->pool_size = newsize;
2309 	return err;
2310 }
2311 
2312 static int drop_one_stripe(struct r5conf *conf)
2313 {
2314 	struct stripe_head *sh;
2315 	int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2316 
2317 	spin_lock_irq(conf->hash_locks + hash);
2318 	sh = get_free_stripe(conf, hash);
2319 	spin_unlock_irq(conf->hash_locks + hash);
2320 	if (!sh)
2321 		return 0;
2322 	BUG_ON(atomic_read(&sh->count));
2323 	shrink_buffers(sh);
2324 	kmem_cache_free(conf->slab_cache, sh);
2325 	atomic_dec(&conf->active_stripes);
2326 	conf->max_nr_stripes--;
2327 	return 1;
2328 }
2329 
2330 static void shrink_stripes(struct r5conf *conf)
2331 {
2332 	while (conf->max_nr_stripes &&
2333 	       drop_one_stripe(conf))
2334 		;
2335 
2336 	kmem_cache_destroy(conf->slab_cache);
2337 	conf->slab_cache = NULL;
2338 }
2339 
2340 static void raid5_end_read_request(struct bio * bi)
2341 {
2342 	struct stripe_head *sh = bi->bi_private;
2343 	struct r5conf *conf = sh->raid_conf;
2344 	int disks = sh->disks, i;
2345 	char b[BDEVNAME_SIZE];
2346 	struct md_rdev *rdev = NULL;
2347 	sector_t s;
2348 
2349 	for (i=0 ; i<disks; i++)
2350 		if (bi == &sh->dev[i].req)
2351 			break;
2352 
2353 	pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2354 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2355 		bi->bi_error);
2356 	if (i == disks) {
2357 		bio_reset(bi);
2358 		BUG();
2359 		return;
2360 	}
2361 	if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2362 		/* If replacement finished while this request was outstanding,
2363 		 * 'replacement' might be NULL already.
2364 		 * In that case it moved down to 'rdev'.
2365 		 * rdev is not removed until all requests are finished.
2366 		 */
2367 		rdev = conf->disks[i].replacement;
2368 	if (!rdev)
2369 		rdev = conf->disks[i].rdev;
2370 
2371 	if (use_new_offset(conf, sh))
2372 		s = sh->sector + rdev->new_data_offset;
2373 	else
2374 		s = sh->sector + rdev->data_offset;
2375 	if (!bi->bi_error) {
2376 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
2377 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2378 			/* Note that this cannot happen on a
2379 			 * replacement device.  We just fail those on
2380 			 * any error
2381 			 */
2382 			pr_info_ratelimited(
2383 				"md/raid:%s: read error corrected (%lu sectors at %llu on %s)\n",
2384 				mdname(conf->mddev), STRIPE_SECTORS,
2385 				(unsigned long long)s,
2386 				bdevname(rdev->bdev, b));
2387 			atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2388 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2389 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2390 		} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2391 			clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2392 
2393 		if (test_bit(R5_InJournal, &sh->dev[i].flags))
2394 			/*
2395 			 * end read for a page in journal, this
2396 			 * must be preparing for prexor in rmw
2397 			 */
2398 			set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
2399 
2400 		if (atomic_read(&rdev->read_errors))
2401 			atomic_set(&rdev->read_errors, 0);
2402 	} else {
2403 		const char *bdn = bdevname(rdev->bdev, b);
2404 		int retry = 0;
2405 		int set_bad = 0;
2406 
2407 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2408 		atomic_inc(&rdev->read_errors);
2409 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2410 			pr_warn_ratelimited(
2411 				"md/raid:%s: read error on replacement device (sector %llu on %s).\n",
2412 				mdname(conf->mddev),
2413 				(unsigned long long)s,
2414 				bdn);
2415 		else if (conf->mddev->degraded >= conf->max_degraded) {
2416 			set_bad = 1;
2417 			pr_warn_ratelimited(
2418 				"md/raid:%s: read error not correctable (sector %llu on %s).\n",
2419 				mdname(conf->mddev),
2420 				(unsigned long long)s,
2421 				bdn);
2422 		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2423 			/* Oh, no!!! */
2424 			set_bad = 1;
2425 			pr_warn_ratelimited(
2426 				"md/raid:%s: read error NOT corrected!! (sector %llu on %s).\n",
2427 				mdname(conf->mddev),
2428 				(unsigned long long)s,
2429 				bdn);
2430 		} else if (atomic_read(&rdev->read_errors)
2431 			 > conf->max_nr_stripes)
2432 			pr_warn("md/raid:%s: Too many read errors, failing device %s.\n",
2433 			       mdname(conf->mddev), bdn);
2434 		else
2435 			retry = 1;
2436 		if (set_bad && test_bit(In_sync, &rdev->flags)
2437 		    && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2438 			retry = 1;
2439 		if (retry)
2440 			if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2441 				set_bit(R5_ReadError, &sh->dev[i].flags);
2442 				clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2443 			} else
2444 				set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2445 		else {
2446 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2447 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2448 			if (!(set_bad
2449 			      && test_bit(In_sync, &rdev->flags)
2450 			      && rdev_set_badblocks(
2451 				      rdev, sh->sector, STRIPE_SECTORS, 0)))
2452 				md_error(conf->mddev, rdev);
2453 		}
2454 	}
2455 	rdev_dec_pending(rdev, conf->mddev);
2456 	bio_reset(bi);
2457 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
2458 	set_bit(STRIPE_HANDLE, &sh->state);
2459 	raid5_release_stripe(sh);
2460 }
2461 
2462 static void raid5_end_write_request(struct bio *bi)
2463 {
2464 	struct stripe_head *sh = bi->bi_private;
2465 	struct r5conf *conf = sh->raid_conf;
2466 	int disks = sh->disks, i;
2467 	struct md_rdev *uninitialized_var(rdev);
2468 	sector_t first_bad;
2469 	int bad_sectors;
2470 	int replacement = 0;
2471 
2472 	for (i = 0 ; i < disks; i++) {
2473 		if (bi == &sh->dev[i].req) {
2474 			rdev = conf->disks[i].rdev;
2475 			break;
2476 		}
2477 		if (bi == &sh->dev[i].rreq) {
2478 			rdev = conf->disks[i].replacement;
2479 			if (rdev)
2480 				replacement = 1;
2481 			else
2482 				/* rdev was removed and 'replacement'
2483 				 * replaced it.  rdev is not removed
2484 				 * until all requests are finished.
2485 				 */
2486 				rdev = conf->disks[i].rdev;
2487 			break;
2488 		}
2489 	}
2490 	pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2491 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2492 		bi->bi_error);
2493 	if (i == disks) {
2494 		bio_reset(bi);
2495 		BUG();
2496 		return;
2497 	}
2498 
2499 	if (replacement) {
2500 		if (bi->bi_error)
2501 			md_error(conf->mddev, rdev);
2502 		else if (is_badblock(rdev, sh->sector,
2503 				     STRIPE_SECTORS,
2504 				     &first_bad, &bad_sectors))
2505 			set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2506 	} else {
2507 		if (bi->bi_error) {
2508 			set_bit(STRIPE_DEGRADED, &sh->state);
2509 			set_bit(WriteErrorSeen, &rdev->flags);
2510 			set_bit(R5_WriteError, &sh->dev[i].flags);
2511 			if (!test_and_set_bit(WantReplacement, &rdev->flags))
2512 				set_bit(MD_RECOVERY_NEEDED,
2513 					&rdev->mddev->recovery);
2514 		} else if (is_badblock(rdev, sh->sector,
2515 				       STRIPE_SECTORS,
2516 				       &first_bad, &bad_sectors)) {
2517 			set_bit(R5_MadeGood, &sh->dev[i].flags);
2518 			if (test_bit(R5_ReadError, &sh->dev[i].flags))
2519 				/* That was a successful write so make
2520 				 * sure it looks like we already did
2521 				 * a re-write.
2522 				 */
2523 				set_bit(R5_ReWrite, &sh->dev[i].flags);
2524 		}
2525 	}
2526 	rdev_dec_pending(rdev, conf->mddev);
2527 
2528 	if (sh->batch_head && bi->bi_error && !replacement)
2529 		set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2530 
2531 	bio_reset(bi);
2532 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2533 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2534 	set_bit(STRIPE_HANDLE, &sh->state);
2535 	raid5_release_stripe(sh);
2536 
2537 	if (sh->batch_head && sh != sh->batch_head)
2538 		raid5_release_stripe(sh->batch_head);
2539 }
2540 
2541 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2542 {
2543 	struct r5dev *dev = &sh->dev[i];
2544 
2545 	dev->flags = 0;
2546 	dev->sector = raid5_compute_blocknr(sh, i, previous);
2547 }
2548 
2549 static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
2550 {
2551 	char b[BDEVNAME_SIZE];
2552 	struct r5conf *conf = mddev->private;
2553 	unsigned long flags;
2554 	pr_debug("raid456: error called\n");
2555 
2556 	spin_lock_irqsave(&conf->device_lock, flags);
2557 	clear_bit(In_sync, &rdev->flags);
2558 	mddev->degraded = raid5_calc_degraded(conf);
2559 	spin_unlock_irqrestore(&conf->device_lock, flags);
2560 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2561 
2562 	set_bit(Blocked, &rdev->flags);
2563 	set_bit(Faulty, &rdev->flags);
2564 	set_mask_bits(&mddev->sb_flags, 0,
2565 		      BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
2566 	pr_crit("md/raid:%s: Disk failure on %s, disabling device.\n"
2567 		"md/raid:%s: Operation continuing on %d devices.\n",
2568 		mdname(mddev),
2569 		bdevname(rdev->bdev, b),
2570 		mdname(mddev),
2571 		conf->raid_disks - mddev->degraded);
2572 	r5c_update_on_rdev_error(mddev);
2573 }
2574 
2575 /*
2576  * Input: a 'big' sector number,
2577  * Output: index of the data and parity disk, and the sector # in them.
2578  */
2579 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2580 			      int previous, int *dd_idx,
2581 			      struct stripe_head *sh)
2582 {
2583 	sector_t stripe, stripe2;
2584 	sector_t chunk_number;
2585 	unsigned int chunk_offset;
2586 	int pd_idx, qd_idx;
2587 	int ddf_layout = 0;
2588 	sector_t new_sector;
2589 	int algorithm = previous ? conf->prev_algo
2590 				 : conf->algorithm;
2591 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2592 					 : conf->chunk_sectors;
2593 	int raid_disks = previous ? conf->previous_raid_disks
2594 				  : conf->raid_disks;
2595 	int data_disks = raid_disks - conf->max_degraded;
2596 
2597 	/* First compute the information on this sector */
2598 
2599 	/*
2600 	 * Compute the chunk number and the sector offset inside the chunk
2601 	 */
2602 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
2603 	chunk_number = r_sector;
2604 
2605 	/*
2606 	 * Compute the stripe number
2607 	 */
2608 	stripe = chunk_number;
2609 	*dd_idx = sector_div(stripe, data_disks);
2610 	stripe2 = stripe;
2611 	/*
2612 	 * Select the parity disk based on the user selected algorithm.
2613 	 */
2614 	pd_idx = qd_idx = -1;
2615 	switch(conf->level) {
2616 	case 4:
2617 		pd_idx = data_disks;
2618 		break;
2619 	case 5:
2620 		switch (algorithm) {
2621 		case ALGORITHM_LEFT_ASYMMETRIC:
2622 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2623 			if (*dd_idx >= pd_idx)
2624 				(*dd_idx)++;
2625 			break;
2626 		case ALGORITHM_RIGHT_ASYMMETRIC:
2627 			pd_idx = sector_div(stripe2, raid_disks);
2628 			if (*dd_idx >= pd_idx)
2629 				(*dd_idx)++;
2630 			break;
2631 		case ALGORITHM_LEFT_SYMMETRIC:
2632 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2633 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2634 			break;
2635 		case ALGORITHM_RIGHT_SYMMETRIC:
2636 			pd_idx = sector_div(stripe2, raid_disks);
2637 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2638 			break;
2639 		case ALGORITHM_PARITY_0:
2640 			pd_idx = 0;
2641 			(*dd_idx)++;
2642 			break;
2643 		case ALGORITHM_PARITY_N:
2644 			pd_idx = data_disks;
2645 			break;
2646 		default:
2647 			BUG();
2648 		}
2649 		break;
2650 	case 6:
2651 
2652 		switch (algorithm) {
2653 		case ALGORITHM_LEFT_ASYMMETRIC:
2654 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2655 			qd_idx = pd_idx + 1;
2656 			if (pd_idx == raid_disks-1) {
2657 				(*dd_idx)++;	/* Q D D D P */
2658 				qd_idx = 0;
2659 			} else if (*dd_idx >= pd_idx)
2660 				(*dd_idx) += 2; /* D D P Q D */
2661 			break;
2662 		case ALGORITHM_RIGHT_ASYMMETRIC:
2663 			pd_idx = sector_div(stripe2, raid_disks);
2664 			qd_idx = pd_idx + 1;
2665 			if (pd_idx == raid_disks-1) {
2666 				(*dd_idx)++;	/* Q D D D P */
2667 				qd_idx = 0;
2668 			} else if (*dd_idx >= pd_idx)
2669 				(*dd_idx) += 2; /* D D P Q D */
2670 			break;
2671 		case ALGORITHM_LEFT_SYMMETRIC:
2672 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2673 			qd_idx = (pd_idx + 1) % raid_disks;
2674 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2675 			break;
2676 		case ALGORITHM_RIGHT_SYMMETRIC:
2677 			pd_idx = sector_div(stripe2, raid_disks);
2678 			qd_idx = (pd_idx + 1) % raid_disks;
2679 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2680 			break;
2681 
2682 		case ALGORITHM_PARITY_0:
2683 			pd_idx = 0;
2684 			qd_idx = 1;
2685 			(*dd_idx) += 2;
2686 			break;
2687 		case ALGORITHM_PARITY_N:
2688 			pd_idx = data_disks;
2689 			qd_idx = data_disks + 1;
2690 			break;
2691 
2692 		case ALGORITHM_ROTATING_ZERO_RESTART:
2693 			/* Exactly the same as RIGHT_ASYMMETRIC, but or
2694 			 * of blocks for computing Q is different.
2695 			 */
2696 			pd_idx = sector_div(stripe2, raid_disks);
2697 			qd_idx = pd_idx + 1;
2698 			if (pd_idx == raid_disks-1) {
2699 				(*dd_idx)++;	/* Q D D D P */
2700 				qd_idx = 0;
2701 			} else if (*dd_idx >= pd_idx)
2702 				(*dd_idx) += 2; /* D D P Q D */
2703 			ddf_layout = 1;
2704 			break;
2705 
2706 		case ALGORITHM_ROTATING_N_RESTART:
2707 			/* Same a left_asymmetric, by first stripe is
2708 			 * D D D P Q  rather than
2709 			 * Q D D D P
2710 			 */
2711 			stripe2 += 1;
2712 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2713 			qd_idx = pd_idx + 1;
2714 			if (pd_idx == raid_disks-1) {
2715 				(*dd_idx)++;	/* Q D D D P */
2716 				qd_idx = 0;
2717 			} else if (*dd_idx >= pd_idx)
2718 				(*dd_idx) += 2; /* D D P Q D */
2719 			ddf_layout = 1;
2720 			break;
2721 
2722 		case ALGORITHM_ROTATING_N_CONTINUE:
2723 			/* Same as left_symmetric but Q is before P */
2724 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2725 			qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2726 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2727 			ddf_layout = 1;
2728 			break;
2729 
2730 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2731 			/* RAID5 left_asymmetric, with Q on last device */
2732 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2733 			if (*dd_idx >= pd_idx)
2734 				(*dd_idx)++;
2735 			qd_idx = raid_disks - 1;
2736 			break;
2737 
2738 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2739 			pd_idx = sector_div(stripe2, raid_disks-1);
2740 			if (*dd_idx >= pd_idx)
2741 				(*dd_idx)++;
2742 			qd_idx = raid_disks - 1;
2743 			break;
2744 
2745 		case ALGORITHM_LEFT_SYMMETRIC_6:
2746 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2747 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2748 			qd_idx = raid_disks - 1;
2749 			break;
2750 
2751 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2752 			pd_idx = sector_div(stripe2, raid_disks-1);
2753 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2754 			qd_idx = raid_disks - 1;
2755 			break;
2756 
2757 		case ALGORITHM_PARITY_0_6:
2758 			pd_idx = 0;
2759 			(*dd_idx)++;
2760 			qd_idx = raid_disks - 1;
2761 			break;
2762 
2763 		default:
2764 			BUG();
2765 		}
2766 		break;
2767 	}
2768 
2769 	if (sh) {
2770 		sh->pd_idx = pd_idx;
2771 		sh->qd_idx = qd_idx;
2772 		sh->ddf_layout = ddf_layout;
2773 	}
2774 	/*
2775 	 * Finally, compute the new sector number
2776 	 */
2777 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2778 	return new_sector;
2779 }
2780 
2781 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
2782 {
2783 	struct r5conf *conf = sh->raid_conf;
2784 	int raid_disks = sh->disks;
2785 	int data_disks = raid_disks - conf->max_degraded;
2786 	sector_t new_sector = sh->sector, check;
2787 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2788 					 : conf->chunk_sectors;
2789 	int algorithm = previous ? conf->prev_algo
2790 				 : conf->algorithm;
2791 	sector_t stripe;
2792 	int chunk_offset;
2793 	sector_t chunk_number;
2794 	int dummy1, dd_idx = i;
2795 	sector_t r_sector;
2796 	struct stripe_head sh2;
2797 
2798 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
2799 	stripe = new_sector;
2800 
2801 	if (i == sh->pd_idx)
2802 		return 0;
2803 	switch(conf->level) {
2804 	case 4: break;
2805 	case 5:
2806 		switch (algorithm) {
2807 		case ALGORITHM_LEFT_ASYMMETRIC:
2808 		case ALGORITHM_RIGHT_ASYMMETRIC:
2809 			if (i > sh->pd_idx)
2810 				i--;
2811 			break;
2812 		case ALGORITHM_LEFT_SYMMETRIC:
2813 		case ALGORITHM_RIGHT_SYMMETRIC:
2814 			if (i < sh->pd_idx)
2815 				i += raid_disks;
2816 			i -= (sh->pd_idx + 1);
2817 			break;
2818 		case ALGORITHM_PARITY_0:
2819 			i -= 1;
2820 			break;
2821 		case ALGORITHM_PARITY_N:
2822 			break;
2823 		default:
2824 			BUG();
2825 		}
2826 		break;
2827 	case 6:
2828 		if (i == sh->qd_idx)
2829 			return 0; /* It is the Q disk */
2830 		switch (algorithm) {
2831 		case ALGORITHM_LEFT_ASYMMETRIC:
2832 		case ALGORITHM_RIGHT_ASYMMETRIC:
2833 		case ALGORITHM_ROTATING_ZERO_RESTART:
2834 		case ALGORITHM_ROTATING_N_RESTART:
2835 			if (sh->pd_idx == raid_disks-1)
2836 				i--;	/* Q D D D P */
2837 			else if (i > sh->pd_idx)
2838 				i -= 2; /* D D P Q D */
2839 			break;
2840 		case ALGORITHM_LEFT_SYMMETRIC:
2841 		case ALGORITHM_RIGHT_SYMMETRIC:
2842 			if (sh->pd_idx == raid_disks-1)
2843 				i--; /* Q D D D P */
2844 			else {
2845 				/* D D P Q D */
2846 				if (i < sh->pd_idx)
2847 					i += raid_disks;
2848 				i -= (sh->pd_idx + 2);
2849 			}
2850 			break;
2851 		case ALGORITHM_PARITY_0:
2852 			i -= 2;
2853 			break;
2854 		case ALGORITHM_PARITY_N:
2855 			break;
2856 		case ALGORITHM_ROTATING_N_CONTINUE:
2857 			/* Like left_symmetric, but P is before Q */
2858 			if (sh->pd_idx == 0)
2859 				i--;	/* P D D D Q */
2860 			else {
2861 				/* D D Q P D */
2862 				if (i < sh->pd_idx)
2863 					i += raid_disks;
2864 				i -= (sh->pd_idx + 1);
2865 			}
2866 			break;
2867 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2868 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2869 			if (i > sh->pd_idx)
2870 				i--;
2871 			break;
2872 		case ALGORITHM_LEFT_SYMMETRIC_6:
2873 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2874 			if (i < sh->pd_idx)
2875 				i += data_disks + 1;
2876 			i -= (sh->pd_idx + 1);
2877 			break;
2878 		case ALGORITHM_PARITY_0_6:
2879 			i -= 1;
2880 			break;
2881 		default:
2882 			BUG();
2883 		}
2884 		break;
2885 	}
2886 
2887 	chunk_number = stripe * data_disks + i;
2888 	r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2889 
2890 	check = raid5_compute_sector(conf, r_sector,
2891 				     previous, &dummy1, &sh2);
2892 	if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2893 		|| sh2.qd_idx != sh->qd_idx) {
2894 		pr_warn("md/raid:%s: compute_blocknr: map not correct\n",
2895 			mdname(conf->mddev));
2896 		return 0;
2897 	}
2898 	return r_sector;
2899 }
2900 
2901 /*
2902  * There are cases where we want handle_stripe_dirtying() and
2903  * schedule_reconstruction() to delay towrite to some dev of a stripe.
2904  *
2905  * This function checks whether we want to delay the towrite. Specifically,
2906  * we delay the towrite when:
2907  *
2908  *   1. degraded stripe has a non-overwrite to the missing dev, AND this
2909  *      stripe has data in journal (for other devices).
2910  *
2911  *      In this case, when reading data for the non-overwrite dev, it is
2912  *      necessary to handle complex rmw of write back cache (prexor with
2913  *      orig_page, and xor with page). To keep read path simple, we would
2914  *      like to flush data in journal to RAID disks first, so complex rmw
2915  *      is handled in the write patch (handle_stripe_dirtying).
2916  *
2917  */
2918 static inline bool delay_towrite(struct r5dev *dev,
2919 				   struct stripe_head_state *s)
2920 {
2921 	return !test_bit(R5_OVERWRITE, &dev->flags) &&
2922 		!test_bit(R5_Insync, &dev->flags) && s->injournal;
2923 }
2924 
2925 static void
2926 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2927 			 int rcw, int expand)
2928 {
2929 	int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
2930 	struct r5conf *conf = sh->raid_conf;
2931 	int level = conf->level;
2932 
2933 	if (rcw) {
2934 		/*
2935 		 * In some cases, handle_stripe_dirtying initially decided to
2936 		 * run rmw and allocates extra page for prexor. However, rcw is
2937 		 * cheaper later on. We need to free the extra page now,
2938 		 * because we won't be able to do that in ops_complete_prexor().
2939 		 */
2940 		r5c_release_extra_page(sh);
2941 
2942 		for (i = disks; i--; ) {
2943 			struct r5dev *dev = &sh->dev[i];
2944 
2945 			if (dev->towrite && !delay_towrite(dev, s)) {
2946 				set_bit(R5_LOCKED, &dev->flags);
2947 				set_bit(R5_Wantdrain, &dev->flags);
2948 				if (!expand)
2949 					clear_bit(R5_UPTODATE, &dev->flags);
2950 				s->locked++;
2951 			} else if (test_bit(R5_InJournal, &dev->flags)) {
2952 				set_bit(R5_LOCKED, &dev->flags);
2953 				s->locked++;
2954 			}
2955 		}
2956 		/* if we are not expanding this is a proper write request, and
2957 		 * there will be bios with new data to be drained into the
2958 		 * stripe cache
2959 		 */
2960 		if (!expand) {
2961 			if (!s->locked)
2962 				/* False alarm, nothing to do */
2963 				return;
2964 			sh->reconstruct_state = reconstruct_state_drain_run;
2965 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2966 		} else
2967 			sh->reconstruct_state = reconstruct_state_run;
2968 
2969 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2970 
2971 		if (s->locked + conf->max_degraded == disks)
2972 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2973 				atomic_inc(&conf->pending_full_writes);
2974 	} else {
2975 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2976 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2977 		BUG_ON(level == 6 &&
2978 			(!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
2979 			   test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
2980 
2981 		for (i = disks; i--; ) {
2982 			struct r5dev *dev = &sh->dev[i];
2983 			if (i == pd_idx || i == qd_idx)
2984 				continue;
2985 
2986 			if (dev->towrite &&
2987 			    (test_bit(R5_UPTODATE, &dev->flags) ||
2988 			     test_bit(R5_Wantcompute, &dev->flags))) {
2989 				set_bit(R5_Wantdrain, &dev->flags);
2990 				set_bit(R5_LOCKED, &dev->flags);
2991 				clear_bit(R5_UPTODATE, &dev->flags);
2992 				s->locked++;
2993 			} else if (test_bit(R5_InJournal, &dev->flags)) {
2994 				set_bit(R5_LOCKED, &dev->flags);
2995 				s->locked++;
2996 			}
2997 		}
2998 		if (!s->locked)
2999 			/* False alarm - nothing to do */
3000 			return;
3001 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
3002 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
3003 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3004 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3005 	}
3006 
3007 	/* keep the parity disk(s) locked while asynchronous operations
3008 	 * are in flight
3009 	 */
3010 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
3011 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3012 	s->locked++;
3013 
3014 	if (level == 6) {
3015 		int qd_idx = sh->qd_idx;
3016 		struct r5dev *dev = &sh->dev[qd_idx];
3017 
3018 		set_bit(R5_LOCKED, &dev->flags);
3019 		clear_bit(R5_UPTODATE, &dev->flags);
3020 		s->locked++;
3021 	}
3022 
3023 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
3024 		__func__, (unsigned long long)sh->sector,
3025 		s->locked, s->ops_request);
3026 }
3027 
3028 /*
3029  * Each stripe/dev can have one or more bion attached.
3030  * toread/towrite point to the first in a chain.
3031  * The bi_next chain must be in order.
3032  */
3033 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
3034 			  int forwrite, int previous)
3035 {
3036 	struct bio **bip;
3037 	struct r5conf *conf = sh->raid_conf;
3038 	int firstwrite=0;
3039 
3040 	pr_debug("adding bi b#%llu to stripe s#%llu\n",
3041 		(unsigned long long)bi->bi_iter.bi_sector,
3042 		(unsigned long long)sh->sector);
3043 
3044 	/*
3045 	 * If several bio share a stripe. The bio bi_phys_segments acts as a
3046 	 * reference count to avoid race. The reference count should already be
3047 	 * increased before this function is called (for example, in
3048 	 * raid5_make_request()), so other bio sharing this stripe will not free the
3049 	 * stripe. If a stripe is owned by one stripe, the stripe lock will
3050 	 * protect it.
3051 	 */
3052 	spin_lock_irq(&sh->stripe_lock);
3053 	/* Don't allow new IO added to stripes in batch list */
3054 	if (sh->batch_head)
3055 		goto overlap;
3056 	if (forwrite) {
3057 		bip = &sh->dev[dd_idx].towrite;
3058 		if (*bip == NULL)
3059 			firstwrite = 1;
3060 	} else
3061 		bip = &sh->dev[dd_idx].toread;
3062 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
3063 		if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
3064 			goto overlap;
3065 		bip = & (*bip)->bi_next;
3066 	}
3067 	if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
3068 		goto overlap;
3069 
3070 	if (!forwrite || previous)
3071 		clear_bit(STRIPE_BATCH_READY, &sh->state);
3072 
3073 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3074 	if (*bip)
3075 		bi->bi_next = *bip;
3076 	*bip = bi;
3077 	raid5_inc_bi_active_stripes(bi);
3078 
3079 	if (forwrite) {
3080 		/* check if page is covered */
3081 		sector_t sector = sh->dev[dd_idx].sector;
3082 		for (bi=sh->dev[dd_idx].towrite;
3083 		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
3084 			     bi && bi->bi_iter.bi_sector <= sector;
3085 		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
3086 			if (bio_end_sector(bi) >= sector)
3087 				sector = bio_end_sector(bi);
3088 		}
3089 		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
3090 			if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3091 				sh->overwrite_disks++;
3092 	}
3093 
3094 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3095 		(unsigned long long)(*bip)->bi_iter.bi_sector,
3096 		(unsigned long long)sh->sector, dd_idx);
3097 
3098 	if (conf->mddev->bitmap && firstwrite) {
3099 		/* Cannot hold spinlock over bitmap_startwrite,
3100 		 * but must ensure this isn't added to a batch until
3101 		 * we have added to the bitmap and set bm_seq.
3102 		 * So set STRIPE_BITMAP_PENDING to prevent
3103 		 * batching.
3104 		 * If multiple add_stripe_bio() calls race here they
3105 		 * much all set STRIPE_BITMAP_PENDING.  So only the first one
3106 		 * to complete "bitmap_startwrite" gets to set
3107 		 * STRIPE_BIT_DELAY.  This is important as once a stripe
3108 		 * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3109 		 * any more.
3110 		 */
3111 		set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3112 		spin_unlock_irq(&sh->stripe_lock);
3113 		bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3114 				  STRIPE_SECTORS, 0);
3115 		spin_lock_irq(&sh->stripe_lock);
3116 		clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3117 		if (!sh->batch_head) {
3118 			sh->bm_seq = conf->seq_flush+1;
3119 			set_bit(STRIPE_BIT_DELAY, &sh->state);
3120 		}
3121 	}
3122 	spin_unlock_irq(&sh->stripe_lock);
3123 
3124 	if (stripe_can_batch(sh))
3125 		stripe_add_to_batch_list(conf, sh);
3126 	return 1;
3127 
3128  overlap:
3129 	set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3130 	spin_unlock_irq(&sh->stripe_lock);
3131 	return 0;
3132 }
3133 
3134 static void end_reshape(struct r5conf *conf);
3135 
3136 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3137 			    struct stripe_head *sh)
3138 {
3139 	int sectors_per_chunk =
3140 		previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3141 	int dd_idx;
3142 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
3143 	int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3144 
3145 	raid5_compute_sector(conf,
3146 			     stripe * (disks - conf->max_degraded)
3147 			     *sectors_per_chunk + chunk_offset,
3148 			     previous,
3149 			     &dd_idx, sh);
3150 }
3151 
3152 static void
3153 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3154 				struct stripe_head_state *s, int disks,
3155 				struct bio_list *return_bi)
3156 {
3157 	int i;
3158 	BUG_ON(sh->batch_head);
3159 	for (i = disks; i--; ) {
3160 		struct bio *bi;
3161 		int bitmap_end = 0;
3162 
3163 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3164 			struct md_rdev *rdev;
3165 			rcu_read_lock();
3166 			rdev = rcu_dereference(conf->disks[i].rdev);
3167 			if (rdev && test_bit(In_sync, &rdev->flags) &&
3168 			    !test_bit(Faulty, &rdev->flags))
3169 				atomic_inc(&rdev->nr_pending);
3170 			else
3171 				rdev = NULL;
3172 			rcu_read_unlock();
3173 			if (rdev) {
3174 				if (!rdev_set_badblocks(
3175 					    rdev,
3176 					    sh->sector,
3177 					    STRIPE_SECTORS, 0))
3178 					md_error(conf->mddev, rdev);
3179 				rdev_dec_pending(rdev, conf->mddev);
3180 			}
3181 		}
3182 		spin_lock_irq(&sh->stripe_lock);
3183 		/* fail all writes first */
3184 		bi = sh->dev[i].towrite;
3185 		sh->dev[i].towrite = NULL;
3186 		sh->overwrite_disks = 0;
3187 		spin_unlock_irq(&sh->stripe_lock);
3188 		if (bi)
3189 			bitmap_end = 1;
3190 
3191 		r5l_stripe_write_finished(sh);
3192 
3193 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3194 			wake_up(&conf->wait_for_overlap);
3195 
3196 		while (bi && bi->bi_iter.bi_sector <
3197 			sh->dev[i].sector + STRIPE_SECTORS) {
3198 			struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3199 
3200 			bi->bi_error = -EIO;
3201 			if (!raid5_dec_bi_active_stripes(bi)) {
3202 				md_write_end(conf->mddev);
3203 				bio_list_add(return_bi, bi);
3204 			}
3205 			bi = nextbi;
3206 		}
3207 		if (bitmap_end)
3208 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3209 				STRIPE_SECTORS, 0, 0);
3210 		bitmap_end = 0;
3211 		/* and fail all 'written' */
3212 		bi = sh->dev[i].written;
3213 		sh->dev[i].written = NULL;
3214 		if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3215 			WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3216 			sh->dev[i].page = sh->dev[i].orig_page;
3217 		}
3218 
3219 		if (bi) bitmap_end = 1;
3220 		while (bi && bi->bi_iter.bi_sector <
3221 		       sh->dev[i].sector + STRIPE_SECTORS) {
3222 			struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3223 
3224 			bi->bi_error = -EIO;
3225 			if (!raid5_dec_bi_active_stripes(bi)) {
3226 				md_write_end(conf->mddev);
3227 				bio_list_add(return_bi, bi);
3228 			}
3229 			bi = bi2;
3230 		}
3231 
3232 		/* fail any reads if this device is non-operational and
3233 		 * the data has not reached the cache yet.
3234 		 */
3235 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3236 		    s->failed > conf->max_degraded &&
3237 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3238 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
3239 			spin_lock_irq(&sh->stripe_lock);
3240 			bi = sh->dev[i].toread;
3241 			sh->dev[i].toread = NULL;
3242 			spin_unlock_irq(&sh->stripe_lock);
3243 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3244 				wake_up(&conf->wait_for_overlap);
3245 			if (bi)
3246 				s->to_read--;
3247 			while (bi && bi->bi_iter.bi_sector <
3248 			       sh->dev[i].sector + STRIPE_SECTORS) {
3249 				struct bio *nextbi =
3250 					r5_next_bio(bi, sh->dev[i].sector);
3251 
3252 				bi->bi_error = -EIO;
3253 				if (!raid5_dec_bi_active_stripes(bi))
3254 					bio_list_add(return_bi, bi);
3255 				bi = nextbi;
3256 			}
3257 		}
3258 		if (bitmap_end)
3259 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3260 					STRIPE_SECTORS, 0, 0);
3261 		/* If we were in the middle of a write the parity block might
3262 		 * still be locked - so just clear all R5_LOCKED flags
3263 		 */
3264 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
3265 	}
3266 	s->to_write = 0;
3267 	s->written = 0;
3268 
3269 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3270 		if (atomic_dec_and_test(&conf->pending_full_writes))
3271 			md_wakeup_thread(conf->mddev->thread);
3272 }
3273 
3274 static void
3275 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3276 		   struct stripe_head_state *s)
3277 {
3278 	int abort = 0;
3279 	int i;
3280 
3281 	BUG_ON(sh->batch_head);
3282 	clear_bit(STRIPE_SYNCING, &sh->state);
3283 	if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3284 		wake_up(&conf->wait_for_overlap);
3285 	s->syncing = 0;
3286 	s->replacing = 0;
3287 	/* There is nothing more to do for sync/check/repair.
3288 	 * Don't even need to abort as that is handled elsewhere
3289 	 * if needed, and not always wanted e.g. if there is a known
3290 	 * bad block here.
3291 	 * For recover/replace we need to record a bad block on all
3292 	 * non-sync devices, or abort the recovery
3293 	 */
3294 	if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3295 		/* During recovery devices cannot be removed, so
3296 		 * locking and refcounting of rdevs is not needed
3297 		 */
3298 		rcu_read_lock();
3299 		for (i = 0; i < conf->raid_disks; i++) {
3300 			struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
3301 			if (rdev
3302 			    && !test_bit(Faulty, &rdev->flags)
3303 			    && !test_bit(In_sync, &rdev->flags)
3304 			    && !rdev_set_badblocks(rdev, sh->sector,
3305 						   STRIPE_SECTORS, 0))
3306 				abort = 1;
3307 			rdev = rcu_dereference(conf->disks[i].replacement);
3308 			if (rdev
3309 			    && !test_bit(Faulty, &rdev->flags)
3310 			    && !test_bit(In_sync, &rdev->flags)
3311 			    && !rdev_set_badblocks(rdev, sh->sector,
3312 						   STRIPE_SECTORS, 0))
3313 				abort = 1;
3314 		}
3315 		rcu_read_unlock();
3316 		if (abort)
3317 			conf->recovery_disabled =
3318 				conf->mddev->recovery_disabled;
3319 	}
3320 	md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3321 }
3322 
3323 static int want_replace(struct stripe_head *sh, int disk_idx)
3324 {
3325 	struct md_rdev *rdev;
3326 	int rv = 0;
3327 
3328 	rcu_read_lock();
3329 	rdev = rcu_dereference(sh->raid_conf->disks[disk_idx].replacement);
3330 	if (rdev
3331 	    && !test_bit(Faulty, &rdev->flags)
3332 	    && !test_bit(In_sync, &rdev->flags)
3333 	    && (rdev->recovery_offset <= sh->sector
3334 		|| rdev->mddev->recovery_cp <= sh->sector))
3335 		rv = 1;
3336 	rcu_read_unlock();
3337 	return rv;
3338 }
3339 
3340 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3341 			   int disk_idx, int disks)
3342 {
3343 	struct r5dev *dev = &sh->dev[disk_idx];
3344 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3345 				  &sh->dev[s->failed_num[1]] };
3346 	int i;
3347 
3348 
3349 	if (test_bit(R5_LOCKED, &dev->flags) ||
3350 	    test_bit(R5_UPTODATE, &dev->flags))
3351 		/* No point reading this as we already have it or have
3352 		 * decided to get it.
3353 		 */
3354 		return 0;
3355 
3356 	if (dev->toread ||
3357 	    (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3358 		/* We need this block to directly satisfy a request */
3359 		return 1;
3360 
3361 	if (s->syncing || s->expanding ||
3362 	    (s->replacing && want_replace(sh, disk_idx)))
3363 		/* When syncing, or expanding we read everything.
3364 		 * When replacing, we need the replaced block.
3365 		 */
3366 		return 1;
3367 
3368 	if ((s->failed >= 1 && fdev[0]->toread) ||
3369 	    (s->failed >= 2 && fdev[1]->toread))
3370 		/* If we want to read from a failed device, then
3371 		 * we need to actually read every other device.
3372 		 */
3373 		return 1;
3374 
3375 	/* Sometimes neither read-modify-write nor reconstruct-write
3376 	 * cycles can work.  In those cases we read every block we
3377 	 * can.  Then the parity-update is certain to have enough to
3378 	 * work with.
3379 	 * This can only be a problem when we need to write something,
3380 	 * and some device has failed.  If either of those tests
3381 	 * fail we need look no further.
3382 	 */
3383 	if (!s->failed || !s->to_write)
3384 		return 0;
3385 
3386 	if (test_bit(R5_Insync, &dev->flags) &&
3387 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3388 		/* Pre-reads at not permitted until after short delay
3389 		 * to gather multiple requests.  However if this
3390 		 * device is no Insync, the block could only be be computed
3391 		 * and there is no need to delay that.
3392 		 */
3393 		return 0;
3394 
3395 	for (i = 0; i < s->failed && i < 2; i++) {
3396 		if (fdev[i]->towrite &&
3397 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3398 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3399 			/* If we have a partial write to a failed
3400 			 * device, then we will need to reconstruct
3401 			 * the content of that device, so all other
3402 			 * devices must be read.
3403 			 */
3404 			return 1;
3405 	}
3406 
3407 	/* If we are forced to do a reconstruct-write, either because
3408 	 * the current RAID6 implementation only supports that, or
3409 	 * or because parity cannot be trusted and we are currently
3410 	 * recovering it, there is extra need to be careful.
3411 	 * If one of the devices that we would need to read, because
3412 	 * it is not being overwritten (and maybe not written at all)
3413 	 * is missing/faulty, then we need to read everything we can.
3414 	 */
3415 	if (sh->raid_conf->level != 6 &&
3416 	    sh->sector < sh->raid_conf->mddev->recovery_cp)
3417 		/* reconstruct-write isn't being forced */
3418 		return 0;
3419 	for (i = 0; i < s->failed && i < 2; i++) {
3420 		if (s->failed_num[i] != sh->pd_idx &&
3421 		    s->failed_num[i] != sh->qd_idx &&
3422 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3423 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3424 			return 1;
3425 	}
3426 
3427 	return 0;
3428 }
3429 
3430 /* fetch_block - checks the given member device to see if its data needs
3431  * to be read or computed to satisfy a request.
3432  *
3433  * Returns 1 when no more member devices need to be checked, otherwise returns
3434  * 0 to tell the loop in handle_stripe_fill to continue
3435  */
3436 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3437 		       int disk_idx, int disks)
3438 {
3439 	struct r5dev *dev = &sh->dev[disk_idx];
3440 
3441 	/* is the data in this block needed, and can we get it? */
3442 	if (need_this_block(sh, s, disk_idx, disks)) {
3443 		/* we would like to get this block, possibly by computing it,
3444 		 * otherwise read it if the backing disk is insync
3445 		 */
3446 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3447 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
3448 		BUG_ON(sh->batch_head);
3449 		if ((s->uptodate == disks - 1) &&
3450 		    (s->failed && (disk_idx == s->failed_num[0] ||
3451 				   disk_idx == s->failed_num[1]))) {
3452 			/* have disk failed, and we're requested to fetch it;
3453 			 * do compute it
3454 			 */
3455 			pr_debug("Computing stripe %llu block %d\n",
3456 			       (unsigned long long)sh->sector, disk_idx);
3457 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3458 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3459 			set_bit(R5_Wantcompute, &dev->flags);
3460 			sh->ops.target = disk_idx;
3461 			sh->ops.target2 = -1; /* no 2nd target */
3462 			s->req_compute = 1;
3463 			/* Careful: from this point on 'uptodate' is in the eye
3464 			 * of raid_run_ops which services 'compute' operations
3465 			 * before writes. R5_Wantcompute flags a block that will
3466 			 * be R5_UPTODATE by the time it is needed for a
3467 			 * subsequent operation.
3468 			 */
3469 			s->uptodate++;
3470 			return 1;
3471 		} else if (s->uptodate == disks-2 && s->failed >= 2) {
3472 			/* Computing 2-failure is *very* expensive; only
3473 			 * do it if failed >= 2
3474 			 */
3475 			int other;
3476 			for (other = disks; other--; ) {
3477 				if (other == disk_idx)
3478 					continue;
3479 				if (!test_bit(R5_UPTODATE,
3480 				      &sh->dev[other].flags))
3481 					break;
3482 			}
3483 			BUG_ON(other < 0);
3484 			pr_debug("Computing stripe %llu blocks %d,%d\n",
3485 			       (unsigned long long)sh->sector,
3486 			       disk_idx, other);
3487 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3488 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3489 			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3490 			set_bit(R5_Wantcompute, &sh->dev[other].flags);
3491 			sh->ops.target = disk_idx;
3492 			sh->ops.target2 = other;
3493 			s->uptodate += 2;
3494 			s->req_compute = 1;
3495 			return 1;
3496 		} else if (test_bit(R5_Insync, &dev->flags)) {
3497 			set_bit(R5_LOCKED, &dev->flags);
3498 			set_bit(R5_Wantread, &dev->flags);
3499 			s->locked++;
3500 			pr_debug("Reading block %d (sync=%d)\n",
3501 				disk_idx, s->syncing);
3502 		}
3503 	}
3504 
3505 	return 0;
3506 }
3507 
3508 /**
3509  * handle_stripe_fill - read or compute data to satisfy pending requests.
3510  */
3511 static void handle_stripe_fill(struct stripe_head *sh,
3512 			       struct stripe_head_state *s,
3513 			       int disks)
3514 {
3515 	int i;
3516 
3517 	/* look for blocks to read/compute, skip this if a compute
3518 	 * is already in flight, or if the stripe contents are in the
3519 	 * midst of changing due to a write
3520 	 */
3521 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3522 	    !sh->reconstruct_state) {
3523 
3524 		/*
3525 		 * For degraded stripe with data in journal, do not handle
3526 		 * read requests yet, instead, flush the stripe to raid
3527 		 * disks first, this avoids handling complex rmw of write
3528 		 * back cache (prexor with orig_page, and then xor with
3529 		 * page) in the read path
3530 		 */
3531 		if (s->injournal && s->failed) {
3532 			if (test_bit(STRIPE_R5C_CACHING, &sh->state))
3533 				r5c_make_stripe_write_out(sh);
3534 			goto out;
3535 		}
3536 
3537 		for (i = disks; i--; )
3538 			if (fetch_block(sh, s, i, disks))
3539 				break;
3540 	}
3541 out:
3542 	set_bit(STRIPE_HANDLE, &sh->state);
3543 }
3544 
3545 static void break_stripe_batch_list(struct stripe_head *head_sh,
3546 				    unsigned long handle_flags);
3547 /* handle_stripe_clean_event
3548  * any written block on an uptodate or failed drive can be returned.
3549  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3550  * never LOCKED, so we don't need to test 'failed' directly.
3551  */
3552 static void handle_stripe_clean_event(struct r5conf *conf,
3553 	struct stripe_head *sh, int disks, struct bio_list *return_bi)
3554 {
3555 	int i;
3556 	struct r5dev *dev;
3557 	int discard_pending = 0;
3558 	struct stripe_head *head_sh = sh;
3559 	bool do_endio = false;
3560 
3561 	for (i = disks; i--; )
3562 		if (sh->dev[i].written) {
3563 			dev = &sh->dev[i];
3564 			if (!test_bit(R5_LOCKED, &dev->flags) &&
3565 			    (test_bit(R5_UPTODATE, &dev->flags) ||
3566 			     test_bit(R5_Discard, &dev->flags) ||
3567 			     test_bit(R5_SkipCopy, &dev->flags))) {
3568 				/* We can return any write requests */
3569 				struct bio *wbi, *wbi2;
3570 				pr_debug("Return write for disc %d\n", i);
3571 				if (test_and_clear_bit(R5_Discard, &dev->flags))
3572 					clear_bit(R5_UPTODATE, &dev->flags);
3573 				if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3574 					WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3575 				}
3576 				do_endio = true;
3577 
3578 returnbi:
3579 				dev->page = dev->orig_page;
3580 				wbi = dev->written;
3581 				dev->written = NULL;
3582 				while (wbi && wbi->bi_iter.bi_sector <
3583 					dev->sector + STRIPE_SECTORS) {
3584 					wbi2 = r5_next_bio(wbi, dev->sector);
3585 					if (!raid5_dec_bi_active_stripes(wbi)) {
3586 						md_write_end(conf->mddev);
3587 						bio_list_add(return_bi, wbi);
3588 					}
3589 					wbi = wbi2;
3590 				}
3591 				bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3592 						STRIPE_SECTORS,
3593 					 !test_bit(STRIPE_DEGRADED, &sh->state),
3594 						0);
3595 				if (head_sh->batch_head) {
3596 					sh = list_first_entry(&sh->batch_list,
3597 							      struct stripe_head,
3598 							      batch_list);
3599 					if (sh != head_sh) {
3600 						dev = &sh->dev[i];
3601 						goto returnbi;
3602 					}
3603 				}
3604 				sh = head_sh;
3605 				dev = &sh->dev[i];
3606 			} else if (test_bit(R5_Discard, &dev->flags))
3607 				discard_pending = 1;
3608 		}
3609 
3610 	r5l_stripe_write_finished(sh);
3611 
3612 	if (!discard_pending &&
3613 	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3614 		int hash;
3615 		clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3616 		clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3617 		if (sh->qd_idx >= 0) {
3618 			clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3619 			clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3620 		}
3621 		/* now that discard is done we can proceed with any sync */
3622 		clear_bit(STRIPE_DISCARD, &sh->state);
3623 		/*
3624 		 * SCSI discard will change some bio fields and the stripe has
3625 		 * no updated data, so remove it from hash list and the stripe
3626 		 * will be reinitialized
3627 		 */
3628 unhash:
3629 		hash = sh->hash_lock_index;
3630 		spin_lock_irq(conf->hash_locks + hash);
3631 		remove_hash(sh);
3632 		spin_unlock_irq(conf->hash_locks + hash);
3633 		if (head_sh->batch_head) {
3634 			sh = list_first_entry(&sh->batch_list,
3635 					      struct stripe_head, batch_list);
3636 			if (sh != head_sh)
3637 					goto unhash;
3638 		}
3639 		sh = head_sh;
3640 
3641 		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3642 			set_bit(STRIPE_HANDLE, &sh->state);
3643 
3644 	}
3645 
3646 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3647 		if (atomic_dec_and_test(&conf->pending_full_writes))
3648 			md_wakeup_thread(conf->mddev->thread);
3649 
3650 	if (head_sh->batch_head && do_endio)
3651 		break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3652 }
3653 
3654 /*
3655  * For RMW in write back cache, we need extra page in prexor to store the
3656  * old data. This page is stored in dev->orig_page.
3657  *
3658  * This function checks whether we have data for prexor. The exact logic
3659  * is:
3660  *       R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
3661  */
3662 static inline bool uptodate_for_rmw(struct r5dev *dev)
3663 {
3664 	return (test_bit(R5_UPTODATE, &dev->flags)) &&
3665 		(!test_bit(R5_InJournal, &dev->flags) ||
3666 		 test_bit(R5_OrigPageUPTDODATE, &dev->flags));
3667 }
3668 
3669 static int handle_stripe_dirtying(struct r5conf *conf,
3670 				  struct stripe_head *sh,
3671 				  struct stripe_head_state *s,
3672 				  int disks)
3673 {
3674 	int rmw = 0, rcw = 0, i;
3675 	sector_t recovery_cp = conf->mddev->recovery_cp;
3676 
3677 	/* Check whether resync is now happening or should start.
3678 	 * If yes, then the array is dirty (after unclean shutdown or
3679 	 * initial creation), so parity in some stripes might be inconsistent.
3680 	 * In this case, we need to always do reconstruct-write, to ensure
3681 	 * that in case of drive failure or read-error correction, we
3682 	 * generate correct data from the parity.
3683 	 */
3684 	if (conf->rmw_level == PARITY_DISABLE_RMW ||
3685 	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3686 	     s->failed == 0)) {
3687 		/* Calculate the real rcw later - for now make it
3688 		 * look like rcw is cheaper
3689 		 */
3690 		rcw = 1; rmw = 2;
3691 		pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3692 			 conf->rmw_level, (unsigned long long)recovery_cp,
3693 			 (unsigned long long)sh->sector);
3694 	} else for (i = disks; i--; ) {
3695 		/* would I have to read this buffer for read_modify_write */
3696 		struct r5dev *dev = &sh->dev[i];
3697 		if (((dev->towrite && !delay_towrite(dev, s)) ||
3698 		     i == sh->pd_idx || i == sh->qd_idx ||
3699 		     test_bit(R5_InJournal, &dev->flags)) &&
3700 		    !test_bit(R5_LOCKED, &dev->flags) &&
3701 		    !(uptodate_for_rmw(dev) ||
3702 		      test_bit(R5_Wantcompute, &dev->flags))) {
3703 			if (test_bit(R5_Insync, &dev->flags))
3704 				rmw++;
3705 			else
3706 				rmw += 2*disks;  /* cannot read it */
3707 		}
3708 		/* Would I have to read this buffer for reconstruct_write */
3709 		if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3710 		    i != sh->pd_idx && i != sh->qd_idx &&
3711 		    !test_bit(R5_LOCKED, &dev->flags) &&
3712 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
3713 		      test_bit(R5_Wantcompute, &dev->flags))) {
3714 			if (test_bit(R5_Insync, &dev->flags))
3715 				rcw++;
3716 			else
3717 				rcw += 2*disks;
3718 		}
3719 	}
3720 
3721 	pr_debug("for sector %llu, rmw=%d rcw=%d\n",
3722 		(unsigned long long)sh->sector, rmw, rcw);
3723 	set_bit(STRIPE_HANDLE, &sh->state);
3724 	if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
3725 		/* prefer read-modify-write, but need to get some data */
3726 		if (conf->mddev->queue)
3727 			blk_add_trace_msg(conf->mddev->queue,
3728 					  "raid5 rmw %llu %d",
3729 					  (unsigned long long)sh->sector, rmw);
3730 		for (i = disks; i--; ) {
3731 			struct r5dev *dev = &sh->dev[i];
3732 			if (test_bit(R5_InJournal, &dev->flags) &&
3733 			    dev->page == dev->orig_page &&
3734 			    !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {
3735 				/* alloc page for prexor */
3736 				struct page *p = alloc_page(GFP_NOIO);
3737 
3738 				if (p) {
3739 					dev->orig_page = p;
3740 					continue;
3741 				}
3742 
3743 				/*
3744 				 * alloc_page() failed, try use
3745 				 * disk_info->extra_page
3746 				 */
3747 				if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,
3748 						      &conf->cache_state)) {
3749 					r5c_use_extra_page(sh);
3750 					break;
3751 				}
3752 
3753 				/* extra_page in use, add to delayed_list */
3754 				set_bit(STRIPE_DELAYED, &sh->state);
3755 				s->waiting_extra_page = 1;
3756 				return -EAGAIN;
3757 			}
3758 		}
3759 
3760 		for (i = disks; i--; ) {
3761 			struct r5dev *dev = &sh->dev[i];
3762 			if (((dev->towrite && !delay_towrite(dev, s)) ||
3763 			     i == sh->pd_idx || i == sh->qd_idx ||
3764 			     test_bit(R5_InJournal, &dev->flags)) &&
3765 			    !test_bit(R5_LOCKED, &dev->flags) &&
3766 			    !(uptodate_for_rmw(dev) ||
3767 			      test_bit(R5_Wantcompute, &dev->flags)) &&
3768 			    test_bit(R5_Insync, &dev->flags)) {
3769 				if (test_bit(STRIPE_PREREAD_ACTIVE,
3770 					     &sh->state)) {
3771 					pr_debug("Read_old block %d for r-m-w\n",
3772 						 i);
3773 					set_bit(R5_LOCKED, &dev->flags);
3774 					set_bit(R5_Wantread, &dev->flags);
3775 					s->locked++;
3776 				} else {
3777 					set_bit(STRIPE_DELAYED, &sh->state);
3778 					set_bit(STRIPE_HANDLE, &sh->state);
3779 				}
3780 			}
3781 		}
3782 	}
3783 	if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
3784 		/* want reconstruct write, but need to get some data */
3785 		int qread =0;
3786 		rcw = 0;
3787 		for (i = disks; i--; ) {
3788 			struct r5dev *dev = &sh->dev[i];
3789 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3790 			    i != sh->pd_idx && i != sh->qd_idx &&
3791 			    !test_bit(R5_LOCKED, &dev->flags) &&
3792 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
3793 			      test_bit(R5_Wantcompute, &dev->flags))) {
3794 				rcw++;
3795 				if (test_bit(R5_Insync, &dev->flags) &&
3796 				    test_bit(STRIPE_PREREAD_ACTIVE,
3797 					     &sh->state)) {
3798 					pr_debug("Read_old block "
3799 						"%d for Reconstruct\n", i);
3800 					set_bit(R5_LOCKED, &dev->flags);
3801 					set_bit(R5_Wantread, &dev->flags);
3802 					s->locked++;
3803 					qread++;
3804 				} else {
3805 					set_bit(STRIPE_DELAYED, &sh->state);
3806 					set_bit(STRIPE_HANDLE, &sh->state);
3807 				}
3808 			}
3809 		}
3810 		if (rcw && conf->mddev->queue)
3811 			blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3812 					  (unsigned long long)sh->sector,
3813 					  rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3814 	}
3815 
3816 	if (rcw > disks && rmw > disks &&
3817 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3818 		set_bit(STRIPE_DELAYED, &sh->state);
3819 
3820 	/* now if nothing is locked, and if we have enough data,
3821 	 * we can start a write request
3822 	 */
3823 	/* since handle_stripe can be called at any time we need to handle the
3824 	 * case where a compute block operation has been submitted and then a
3825 	 * subsequent call wants to start a write request.  raid_run_ops only
3826 	 * handles the case where compute block and reconstruct are requested
3827 	 * simultaneously.  If this is not the case then new writes need to be
3828 	 * held off until the compute completes.
3829 	 */
3830 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3831 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3832 	     !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3833 		schedule_reconstruction(sh, s, rcw == 0, 0);
3834 	return 0;
3835 }
3836 
3837 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3838 				struct stripe_head_state *s, int disks)
3839 {
3840 	struct r5dev *dev = NULL;
3841 
3842 	BUG_ON(sh->batch_head);
3843 	set_bit(STRIPE_HANDLE, &sh->state);
3844 
3845 	switch (sh->check_state) {
3846 	case check_state_idle:
3847 		/* start a new check operation if there are no failures */
3848 		if (s->failed == 0) {
3849 			BUG_ON(s->uptodate != disks);
3850 			sh->check_state = check_state_run;
3851 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3852 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3853 			s->uptodate--;
3854 			break;
3855 		}
3856 		dev = &sh->dev[s->failed_num[0]];
3857 		/* fall through */
3858 	case check_state_compute_result:
3859 		sh->check_state = check_state_idle;
3860 		if (!dev)
3861 			dev = &sh->dev[sh->pd_idx];
3862 
3863 		/* check that a write has not made the stripe insync */
3864 		if (test_bit(STRIPE_INSYNC, &sh->state))
3865 			break;
3866 
3867 		/* either failed parity check, or recovery is happening */
3868 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3869 		BUG_ON(s->uptodate != disks);
3870 
3871 		set_bit(R5_LOCKED, &dev->flags);
3872 		s->locked++;
3873 		set_bit(R5_Wantwrite, &dev->flags);
3874 
3875 		clear_bit(STRIPE_DEGRADED, &sh->state);
3876 		set_bit(STRIPE_INSYNC, &sh->state);
3877 		break;
3878 	case check_state_run:
3879 		break; /* we will be called again upon completion */
3880 	case check_state_check_result:
3881 		sh->check_state = check_state_idle;
3882 
3883 		/* if a failure occurred during the check operation, leave
3884 		 * STRIPE_INSYNC not set and let the stripe be handled again
3885 		 */
3886 		if (s->failed)
3887 			break;
3888 
3889 		/* handle a successful check operation, if parity is correct
3890 		 * we are done.  Otherwise update the mismatch count and repair
3891 		 * parity if !MD_RECOVERY_CHECK
3892 		 */
3893 		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3894 			/* parity is correct (on disc,
3895 			 * not in buffer any more)
3896 			 */
3897 			set_bit(STRIPE_INSYNC, &sh->state);
3898 		else {
3899 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3900 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3901 				/* don't try to repair!! */
3902 				set_bit(STRIPE_INSYNC, &sh->state);
3903 			else {
3904 				sh->check_state = check_state_compute_run;
3905 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3906 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3907 				set_bit(R5_Wantcompute,
3908 					&sh->dev[sh->pd_idx].flags);
3909 				sh->ops.target = sh->pd_idx;
3910 				sh->ops.target2 = -1;
3911 				s->uptodate++;
3912 			}
3913 		}
3914 		break;
3915 	case check_state_compute_run:
3916 		break;
3917 	default:
3918 		pr_err("%s: unknown check_state: %d sector: %llu\n",
3919 		       __func__, sh->check_state,
3920 		       (unsigned long long) sh->sector);
3921 		BUG();
3922 	}
3923 }
3924 
3925 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3926 				  struct stripe_head_state *s,
3927 				  int disks)
3928 {
3929 	int pd_idx = sh->pd_idx;
3930 	int qd_idx = sh->qd_idx;
3931 	struct r5dev *dev;
3932 
3933 	BUG_ON(sh->batch_head);
3934 	set_bit(STRIPE_HANDLE, &sh->state);
3935 
3936 	BUG_ON(s->failed > 2);
3937 
3938 	/* Want to check and possibly repair P and Q.
3939 	 * However there could be one 'failed' device, in which
3940 	 * case we can only check one of them, possibly using the
3941 	 * other to generate missing data
3942 	 */
3943 
3944 	switch (sh->check_state) {
3945 	case check_state_idle:
3946 		/* start a new check operation if there are < 2 failures */
3947 		if (s->failed == s->q_failed) {
3948 			/* The only possible failed device holds Q, so it
3949 			 * makes sense to check P (If anything else were failed,
3950 			 * we would have used P to recreate it).
3951 			 */
3952 			sh->check_state = check_state_run;
3953 		}
3954 		if (!s->q_failed && s->failed < 2) {
3955 			/* Q is not failed, and we didn't use it to generate
3956 			 * anything, so it makes sense to check it
3957 			 */
3958 			if (sh->check_state == check_state_run)
3959 				sh->check_state = check_state_run_pq;
3960 			else
3961 				sh->check_state = check_state_run_q;
3962 		}
3963 
3964 		/* discard potentially stale zero_sum_result */
3965 		sh->ops.zero_sum_result = 0;
3966 
3967 		if (sh->check_state == check_state_run) {
3968 			/* async_xor_zero_sum destroys the contents of P */
3969 			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3970 			s->uptodate--;
3971 		}
3972 		if (sh->check_state >= check_state_run &&
3973 		    sh->check_state <= check_state_run_pq) {
3974 			/* async_syndrome_zero_sum preserves P and Q, so
3975 			 * no need to mark them !uptodate here
3976 			 */
3977 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3978 			break;
3979 		}
3980 
3981 		/* we have 2-disk failure */
3982 		BUG_ON(s->failed != 2);
3983 		/* fall through */
3984 	case check_state_compute_result:
3985 		sh->check_state = check_state_idle;
3986 
3987 		/* check that a write has not made the stripe insync */
3988 		if (test_bit(STRIPE_INSYNC, &sh->state))
3989 			break;
3990 
3991 		/* now write out any block on a failed drive,
3992 		 * or P or Q if they were recomputed
3993 		 */
3994 		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3995 		if (s->failed == 2) {
3996 			dev = &sh->dev[s->failed_num[1]];
3997 			s->locked++;
3998 			set_bit(R5_LOCKED, &dev->flags);
3999 			set_bit(R5_Wantwrite, &dev->flags);
4000 		}
4001 		if (s->failed >= 1) {
4002 			dev = &sh->dev[s->failed_num[0]];
4003 			s->locked++;
4004 			set_bit(R5_LOCKED, &dev->flags);
4005 			set_bit(R5_Wantwrite, &dev->flags);
4006 		}
4007 		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4008 			dev = &sh->dev[pd_idx];
4009 			s->locked++;
4010 			set_bit(R5_LOCKED, &dev->flags);
4011 			set_bit(R5_Wantwrite, &dev->flags);
4012 		}
4013 		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4014 			dev = &sh->dev[qd_idx];
4015 			s->locked++;
4016 			set_bit(R5_LOCKED, &dev->flags);
4017 			set_bit(R5_Wantwrite, &dev->flags);
4018 		}
4019 		clear_bit(STRIPE_DEGRADED, &sh->state);
4020 
4021 		set_bit(STRIPE_INSYNC, &sh->state);
4022 		break;
4023 	case check_state_run:
4024 	case check_state_run_q:
4025 	case check_state_run_pq:
4026 		break; /* we will be called again upon completion */
4027 	case check_state_check_result:
4028 		sh->check_state = check_state_idle;
4029 
4030 		/* handle a successful check operation, if parity is correct
4031 		 * we are done.  Otherwise update the mismatch count and repair
4032 		 * parity if !MD_RECOVERY_CHECK
4033 		 */
4034 		if (sh->ops.zero_sum_result == 0) {
4035 			/* both parities are correct */
4036 			if (!s->failed)
4037 				set_bit(STRIPE_INSYNC, &sh->state);
4038 			else {
4039 				/* in contrast to the raid5 case we can validate
4040 				 * parity, but still have a failure to write
4041 				 * back
4042 				 */
4043 				sh->check_state = check_state_compute_result;
4044 				/* Returning at this point means that we may go
4045 				 * off and bring p and/or q uptodate again so
4046 				 * we make sure to check zero_sum_result again
4047 				 * to verify if p or q need writeback
4048 				 */
4049 			}
4050 		} else {
4051 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
4052 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
4053 				/* don't try to repair!! */
4054 				set_bit(STRIPE_INSYNC, &sh->state);
4055 			else {
4056 				int *target = &sh->ops.target;
4057 
4058 				sh->ops.target = -1;
4059 				sh->ops.target2 = -1;
4060 				sh->check_state = check_state_compute_run;
4061 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4062 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4063 				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4064 					set_bit(R5_Wantcompute,
4065 						&sh->dev[pd_idx].flags);
4066 					*target = pd_idx;
4067 					target = &sh->ops.target2;
4068 					s->uptodate++;
4069 				}
4070 				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4071 					set_bit(R5_Wantcompute,
4072 						&sh->dev[qd_idx].flags);
4073 					*target = qd_idx;
4074 					s->uptodate++;
4075 				}
4076 			}
4077 		}
4078 		break;
4079 	case check_state_compute_run:
4080 		break;
4081 	default:
4082 		pr_warn("%s: unknown check_state: %d sector: %llu\n",
4083 			__func__, sh->check_state,
4084 			(unsigned long long) sh->sector);
4085 		BUG();
4086 	}
4087 }
4088 
4089 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
4090 {
4091 	int i;
4092 
4093 	/* We have read all the blocks in this stripe and now we need to
4094 	 * copy some of them into a target stripe for expand.
4095 	 */
4096 	struct dma_async_tx_descriptor *tx = NULL;
4097 	BUG_ON(sh->batch_head);
4098 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4099 	for (i = 0; i < sh->disks; i++)
4100 		if (i != sh->pd_idx && i != sh->qd_idx) {
4101 			int dd_idx, j;
4102 			struct stripe_head *sh2;
4103 			struct async_submit_ctl submit;
4104 
4105 			sector_t bn = raid5_compute_blocknr(sh, i, 1);
4106 			sector_t s = raid5_compute_sector(conf, bn, 0,
4107 							  &dd_idx, NULL);
4108 			sh2 = raid5_get_active_stripe(conf, s, 0, 1, 1);
4109 			if (sh2 == NULL)
4110 				/* so far only the early blocks of this stripe
4111 				 * have been requested.  When later blocks
4112 				 * get requested, we will try again
4113 				 */
4114 				continue;
4115 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
4116 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
4117 				/* must have already done this block */
4118 				raid5_release_stripe(sh2);
4119 				continue;
4120 			}
4121 
4122 			/* place all the copies on one channel */
4123 			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4124 			tx = async_memcpy(sh2->dev[dd_idx].page,
4125 					  sh->dev[i].page, 0, 0, STRIPE_SIZE,
4126 					  &submit);
4127 
4128 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4129 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4130 			for (j = 0; j < conf->raid_disks; j++)
4131 				if (j != sh2->pd_idx &&
4132 				    j != sh2->qd_idx &&
4133 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
4134 					break;
4135 			if (j == conf->raid_disks) {
4136 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
4137 				set_bit(STRIPE_HANDLE, &sh2->state);
4138 			}
4139 			raid5_release_stripe(sh2);
4140 
4141 		}
4142 	/* done submitting copies, wait for them to complete */
4143 	async_tx_quiesce(&tx);
4144 }
4145 
4146 /*
4147  * handle_stripe - do things to a stripe.
4148  *
4149  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4150  * state of various bits to see what needs to be done.
4151  * Possible results:
4152  *    return some read requests which now have data
4153  *    return some write requests which are safely on storage
4154  *    schedule a read on some buffers
4155  *    schedule a write of some buffers
4156  *    return confirmation of parity correctness
4157  *
4158  */
4159 
4160 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4161 {
4162 	struct r5conf *conf = sh->raid_conf;
4163 	int disks = sh->disks;
4164 	struct r5dev *dev;
4165 	int i;
4166 	int do_recovery = 0;
4167 
4168 	memset(s, 0, sizeof(*s));
4169 
4170 	s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4171 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4172 	s->failed_num[0] = -1;
4173 	s->failed_num[1] = -1;
4174 	s->log_failed = r5l_log_disk_error(conf);
4175 
4176 	/* Now to look around and see what can be done */
4177 	rcu_read_lock();
4178 	for (i=disks; i--; ) {
4179 		struct md_rdev *rdev;
4180 		sector_t first_bad;
4181 		int bad_sectors;
4182 		int is_bad = 0;
4183 
4184 		dev = &sh->dev[i];
4185 
4186 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4187 			 i, dev->flags,
4188 			 dev->toread, dev->towrite, dev->written);
4189 		/* maybe we can reply to a read
4190 		 *
4191 		 * new wantfill requests are only permitted while
4192 		 * ops_complete_biofill is guaranteed to be inactive
4193 		 */
4194 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4195 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4196 			set_bit(R5_Wantfill, &dev->flags);
4197 
4198 		/* now count some things */
4199 		if (test_bit(R5_LOCKED, &dev->flags))
4200 			s->locked++;
4201 		if (test_bit(R5_UPTODATE, &dev->flags))
4202 			s->uptodate++;
4203 		if (test_bit(R5_Wantcompute, &dev->flags)) {
4204 			s->compute++;
4205 			BUG_ON(s->compute > 2);
4206 		}
4207 
4208 		if (test_bit(R5_Wantfill, &dev->flags))
4209 			s->to_fill++;
4210 		else if (dev->toread)
4211 			s->to_read++;
4212 		if (dev->towrite) {
4213 			s->to_write++;
4214 			if (!test_bit(R5_OVERWRITE, &dev->flags))
4215 				s->non_overwrite++;
4216 		}
4217 		if (dev->written)
4218 			s->written++;
4219 		/* Prefer to use the replacement for reads, but only
4220 		 * if it is recovered enough and has no bad blocks.
4221 		 */
4222 		rdev = rcu_dereference(conf->disks[i].replacement);
4223 		if (rdev && !test_bit(Faulty, &rdev->flags) &&
4224 		    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4225 		    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4226 				 &first_bad, &bad_sectors))
4227 			set_bit(R5_ReadRepl, &dev->flags);
4228 		else {
4229 			if (rdev && !test_bit(Faulty, &rdev->flags))
4230 				set_bit(R5_NeedReplace, &dev->flags);
4231 			else
4232 				clear_bit(R5_NeedReplace, &dev->flags);
4233 			rdev = rcu_dereference(conf->disks[i].rdev);
4234 			clear_bit(R5_ReadRepl, &dev->flags);
4235 		}
4236 		if (rdev && test_bit(Faulty, &rdev->flags))
4237 			rdev = NULL;
4238 		if (rdev) {
4239 			is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4240 					     &first_bad, &bad_sectors);
4241 			if (s->blocked_rdev == NULL
4242 			    && (test_bit(Blocked, &rdev->flags)
4243 				|| is_bad < 0)) {
4244 				if (is_bad < 0)
4245 					set_bit(BlockedBadBlocks,
4246 						&rdev->flags);
4247 				s->blocked_rdev = rdev;
4248 				atomic_inc(&rdev->nr_pending);
4249 			}
4250 		}
4251 		clear_bit(R5_Insync, &dev->flags);
4252 		if (!rdev)
4253 			/* Not in-sync */;
4254 		else if (is_bad) {
4255 			/* also not in-sync */
4256 			if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4257 			    test_bit(R5_UPTODATE, &dev->flags)) {
4258 				/* treat as in-sync, but with a read error
4259 				 * which we can now try to correct
4260 				 */
4261 				set_bit(R5_Insync, &dev->flags);
4262 				set_bit(R5_ReadError, &dev->flags);
4263 			}
4264 		} else if (test_bit(In_sync, &rdev->flags))
4265 			set_bit(R5_Insync, &dev->flags);
4266 		else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4267 			/* in sync if before recovery_offset */
4268 			set_bit(R5_Insync, &dev->flags);
4269 		else if (test_bit(R5_UPTODATE, &dev->flags) &&
4270 			 test_bit(R5_Expanded, &dev->flags))
4271 			/* If we've reshaped into here, we assume it is Insync.
4272 			 * We will shortly update recovery_offset to make
4273 			 * it official.
4274 			 */
4275 			set_bit(R5_Insync, &dev->flags);
4276 
4277 		if (test_bit(R5_WriteError, &dev->flags)) {
4278 			/* This flag does not apply to '.replacement'
4279 			 * only to .rdev, so make sure to check that*/
4280 			struct md_rdev *rdev2 = rcu_dereference(
4281 				conf->disks[i].rdev);
4282 			if (rdev2 == rdev)
4283 				clear_bit(R5_Insync, &dev->flags);
4284 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4285 				s->handle_bad_blocks = 1;
4286 				atomic_inc(&rdev2->nr_pending);
4287 			} else
4288 				clear_bit(R5_WriteError, &dev->flags);
4289 		}
4290 		if (test_bit(R5_MadeGood, &dev->flags)) {
4291 			/* This flag does not apply to '.replacement'
4292 			 * only to .rdev, so make sure to check that*/
4293 			struct md_rdev *rdev2 = rcu_dereference(
4294 				conf->disks[i].rdev);
4295 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4296 				s->handle_bad_blocks = 1;
4297 				atomic_inc(&rdev2->nr_pending);
4298 			} else
4299 				clear_bit(R5_MadeGood, &dev->flags);
4300 		}
4301 		if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4302 			struct md_rdev *rdev2 = rcu_dereference(
4303 				conf->disks[i].replacement);
4304 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4305 				s->handle_bad_blocks = 1;
4306 				atomic_inc(&rdev2->nr_pending);
4307 			} else
4308 				clear_bit(R5_MadeGoodRepl, &dev->flags);
4309 		}
4310 		if (!test_bit(R5_Insync, &dev->flags)) {
4311 			/* The ReadError flag will just be confusing now */
4312 			clear_bit(R5_ReadError, &dev->flags);
4313 			clear_bit(R5_ReWrite, &dev->flags);
4314 		}
4315 		if (test_bit(R5_ReadError, &dev->flags))
4316 			clear_bit(R5_Insync, &dev->flags);
4317 		if (!test_bit(R5_Insync, &dev->flags)) {
4318 			if (s->failed < 2)
4319 				s->failed_num[s->failed] = i;
4320 			s->failed++;
4321 			if (rdev && !test_bit(Faulty, &rdev->flags))
4322 				do_recovery = 1;
4323 		}
4324 
4325 		if (test_bit(R5_InJournal, &dev->flags))
4326 			s->injournal++;
4327 		if (test_bit(R5_InJournal, &dev->flags) && dev->written)
4328 			s->just_cached++;
4329 	}
4330 	if (test_bit(STRIPE_SYNCING, &sh->state)) {
4331 		/* If there is a failed device being replaced,
4332 		 *     we must be recovering.
4333 		 * else if we are after recovery_cp, we must be syncing
4334 		 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4335 		 * else we can only be replacing
4336 		 * sync and recovery both need to read all devices, and so
4337 		 * use the same flag.
4338 		 */
4339 		if (do_recovery ||
4340 		    sh->sector >= conf->mddev->recovery_cp ||
4341 		    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4342 			s->syncing = 1;
4343 		else
4344 			s->replacing = 1;
4345 	}
4346 	rcu_read_unlock();
4347 }
4348 
4349 static int clear_batch_ready(struct stripe_head *sh)
4350 {
4351 	/* Return '1' if this is a member of batch, or
4352 	 * '0' if it is a lone stripe or a head which can now be
4353 	 * handled.
4354 	 */
4355 	struct stripe_head *tmp;
4356 	if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4357 		return (sh->batch_head && sh->batch_head != sh);
4358 	spin_lock(&sh->stripe_lock);
4359 	if (!sh->batch_head) {
4360 		spin_unlock(&sh->stripe_lock);
4361 		return 0;
4362 	}
4363 
4364 	/*
4365 	 * this stripe could be added to a batch list before we check
4366 	 * BATCH_READY, skips it
4367 	 */
4368 	if (sh->batch_head != sh) {
4369 		spin_unlock(&sh->stripe_lock);
4370 		return 1;
4371 	}
4372 	spin_lock(&sh->batch_lock);
4373 	list_for_each_entry(tmp, &sh->batch_list, batch_list)
4374 		clear_bit(STRIPE_BATCH_READY, &tmp->state);
4375 	spin_unlock(&sh->batch_lock);
4376 	spin_unlock(&sh->stripe_lock);
4377 
4378 	/*
4379 	 * BATCH_READY is cleared, no new stripes can be added.
4380 	 * batch_list can be accessed without lock
4381 	 */
4382 	return 0;
4383 }
4384 
4385 static void break_stripe_batch_list(struct stripe_head *head_sh,
4386 				    unsigned long handle_flags)
4387 {
4388 	struct stripe_head *sh, *next;
4389 	int i;
4390 	int do_wakeup = 0;
4391 
4392 	list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4393 
4394 		list_del_init(&sh->batch_list);
4395 
4396 		WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4397 					  (1 << STRIPE_SYNCING) |
4398 					  (1 << STRIPE_REPLACED) |
4399 					  (1 << STRIPE_DELAYED) |
4400 					  (1 << STRIPE_BIT_DELAY) |
4401 					  (1 << STRIPE_FULL_WRITE) |
4402 					  (1 << STRIPE_BIOFILL_RUN) |
4403 					  (1 << STRIPE_COMPUTE_RUN)  |
4404 					  (1 << STRIPE_OPS_REQ_PENDING) |
4405 					  (1 << STRIPE_DISCARD) |
4406 					  (1 << STRIPE_BATCH_READY) |
4407 					  (1 << STRIPE_BATCH_ERR) |
4408 					  (1 << STRIPE_BITMAP_PENDING)),
4409 			"stripe state: %lx\n", sh->state);
4410 		WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4411 					      (1 << STRIPE_REPLACED)),
4412 			"head stripe state: %lx\n", head_sh->state);
4413 
4414 		set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4415 					    (1 << STRIPE_PREREAD_ACTIVE) |
4416 					    (1 << STRIPE_DEGRADED)),
4417 			      head_sh->state & (1 << STRIPE_INSYNC));
4418 
4419 		sh->check_state = head_sh->check_state;
4420 		sh->reconstruct_state = head_sh->reconstruct_state;
4421 		for (i = 0; i < sh->disks; i++) {
4422 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4423 				do_wakeup = 1;
4424 			sh->dev[i].flags = head_sh->dev[i].flags &
4425 				(~((1 << R5_WriteError) | (1 << R5_Overlap)));
4426 		}
4427 		spin_lock_irq(&sh->stripe_lock);
4428 		sh->batch_head = NULL;
4429 		spin_unlock_irq(&sh->stripe_lock);
4430 		if (handle_flags == 0 ||
4431 		    sh->state & handle_flags)
4432 			set_bit(STRIPE_HANDLE, &sh->state);
4433 		raid5_release_stripe(sh);
4434 	}
4435 	spin_lock_irq(&head_sh->stripe_lock);
4436 	head_sh->batch_head = NULL;
4437 	spin_unlock_irq(&head_sh->stripe_lock);
4438 	for (i = 0; i < head_sh->disks; i++)
4439 		if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4440 			do_wakeup = 1;
4441 	if (head_sh->state & handle_flags)
4442 		set_bit(STRIPE_HANDLE, &head_sh->state);
4443 
4444 	if (do_wakeup)
4445 		wake_up(&head_sh->raid_conf->wait_for_overlap);
4446 }
4447 
4448 static void handle_stripe(struct stripe_head *sh)
4449 {
4450 	struct stripe_head_state s;
4451 	struct r5conf *conf = sh->raid_conf;
4452 	int i;
4453 	int prexor;
4454 	int disks = sh->disks;
4455 	struct r5dev *pdev, *qdev;
4456 
4457 	clear_bit(STRIPE_HANDLE, &sh->state);
4458 	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4459 		/* already being handled, ensure it gets handled
4460 		 * again when current action finishes */
4461 		set_bit(STRIPE_HANDLE, &sh->state);
4462 		return;
4463 	}
4464 
4465 	if (clear_batch_ready(sh) ) {
4466 		clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4467 		return;
4468 	}
4469 
4470 	if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4471 		break_stripe_batch_list(sh, 0);
4472 
4473 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4474 		spin_lock(&sh->stripe_lock);
4475 		/* Cannot process 'sync' concurrently with 'discard' */
4476 		if (!test_bit(STRIPE_DISCARD, &sh->state) &&
4477 		    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4478 			set_bit(STRIPE_SYNCING, &sh->state);
4479 			clear_bit(STRIPE_INSYNC, &sh->state);
4480 			clear_bit(STRIPE_REPLACED, &sh->state);
4481 		}
4482 		spin_unlock(&sh->stripe_lock);
4483 	}
4484 	clear_bit(STRIPE_DELAYED, &sh->state);
4485 
4486 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4487 		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4488 	       (unsigned long long)sh->sector, sh->state,
4489 	       atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4490 	       sh->check_state, sh->reconstruct_state);
4491 
4492 	analyse_stripe(sh, &s);
4493 
4494 	if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
4495 		goto finish;
4496 
4497 	if (s.handle_bad_blocks) {
4498 		set_bit(STRIPE_HANDLE, &sh->state);
4499 		goto finish;
4500 	}
4501 
4502 	if (unlikely(s.blocked_rdev)) {
4503 		if (s.syncing || s.expanding || s.expanded ||
4504 		    s.replacing || s.to_write || s.written) {
4505 			set_bit(STRIPE_HANDLE, &sh->state);
4506 			goto finish;
4507 		}
4508 		/* There is nothing for the blocked_rdev to block */
4509 		rdev_dec_pending(s.blocked_rdev, conf->mddev);
4510 		s.blocked_rdev = NULL;
4511 	}
4512 
4513 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4514 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4515 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4516 	}
4517 
4518 	pr_debug("locked=%d uptodate=%d to_read=%d"
4519 	       " to_write=%d failed=%d failed_num=%d,%d\n",
4520 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4521 	       s.failed_num[0], s.failed_num[1]);
4522 	/* check if the array has lost more than max_degraded devices and,
4523 	 * if so, some requests might need to be failed.
4524 	 */
4525 	if (s.failed > conf->max_degraded || s.log_failed) {
4526 		sh->check_state = 0;
4527 		sh->reconstruct_state = 0;
4528 		break_stripe_batch_list(sh, 0);
4529 		if (s.to_read+s.to_write+s.written)
4530 			handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
4531 		if (s.syncing + s.replacing)
4532 			handle_failed_sync(conf, sh, &s);
4533 	}
4534 
4535 	/* Now we check to see if any write operations have recently
4536 	 * completed
4537 	 */
4538 	prexor = 0;
4539 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4540 		prexor = 1;
4541 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
4542 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4543 		sh->reconstruct_state = reconstruct_state_idle;
4544 
4545 		/* All the 'written' buffers and the parity block are ready to
4546 		 * be written back to disk
4547 		 */
4548 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4549 		       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4550 		BUG_ON(sh->qd_idx >= 0 &&
4551 		       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4552 		       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4553 		for (i = disks; i--; ) {
4554 			struct r5dev *dev = &sh->dev[i];
4555 			if (test_bit(R5_LOCKED, &dev->flags) &&
4556 				(i == sh->pd_idx || i == sh->qd_idx ||
4557 				 dev->written || test_bit(R5_InJournal,
4558 							  &dev->flags))) {
4559 				pr_debug("Writing block %d\n", i);
4560 				set_bit(R5_Wantwrite, &dev->flags);
4561 				if (prexor)
4562 					continue;
4563 				if (s.failed > 1)
4564 					continue;
4565 				if (!test_bit(R5_Insync, &dev->flags) ||
4566 				    ((i == sh->pd_idx || i == sh->qd_idx)  &&
4567 				     s.failed == 0))
4568 					set_bit(STRIPE_INSYNC, &sh->state);
4569 			}
4570 		}
4571 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4572 			s.dec_preread_active = 1;
4573 	}
4574 
4575 	/*
4576 	 * might be able to return some write requests if the parity blocks
4577 	 * are safe, or on a failed drive
4578 	 */
4579 	pdev = &sh->dev[sh->pd_idx];
4580 	s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4581 		|| (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4582 	qdev = &sh->dev[sh->qd_idx];
4583 	s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4584 		|| (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4585 		|| conf->level < 6;
4586 
4587 	if (s.written &&
4588 	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4589 			     && !test_bit(R5_LOCKED, &pdev->flags)
4590 			     && (test_bit(R5_UPTODATE, &pdev->flags) ||
4591 				 test_bit(R5_Discard, &pdev->flags))))) &&
4592 	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4593 			     && !test_bit(R5_LOCKED, &qdev->flags)
4594 			     && (test_bit(R5_UPTODATE, &qdev->flags) ||
4595 				 test_bit(R5_Discard, &qdev->flags))))))
4596 		handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
4597 
4598 	if (s.just_cached)
4599 		r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
4600 	r5l_stripe_write_finished(sh);
4601 
4602 	/* Now we might consider reading some blocks, either to check/generate
4603 	 * parity, or to satisfy requests
4604 	 * or to load a block that is being partially written.
4605 	 */
4606 	if (s.to_read || s.non_overwrite
4607 	    || (conf->level == 6 && s.to_write && s.failed)
4608 	    || (s.syncing && (s.uptodate + s.compute < disks))
4609 	    || s.replacing
4610 	    || s.expanding)
4611 		handle_stripe_fill(sh, &s, disks);
4612 
4613 	/*
4614 	 * When the stripe finishes full journal write cycle (write to journal
4615 	 * and raid disk), this is the clean up procedure so it is ready for
4616 	 * next operation.
4617 	 */
4618 	r5c_finish_stripe_write_out(conf, sh, &s);
4619 
4620 	/*
4621 	 * Now to consider new write requests, cache write back and what else,
4622 	 * if anything should be read.  We do not handle new writes when:
4623 	 * 1/ A 'write' operation (copy+xor) is already in flight.
4624 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
4625 	 *    block.
4626 	 * 3/ A r5c cache log write is in flight.
4627 	 */
4628 
4629 	if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
4630 		if (!r5c_is_writeback(conf->log)) {
4631 			if (s.to_write)
4632 				handle_stripe_dirtying(conf, sh, &s, disks);
4633 		} else { /* write back cache */
4634 			int ret = 0;
4635 
4636 			/* First, try handle writes in caching phase */
4637 			if (s.to_write)
4638 				ret = r5c_try_caching_write(conf, sh, &s,
4639 							    disks);
4640 			/*
4641 			 * If caching phase failed: ret == -EAGAIN
4642 			 *    OR
4643 			 * stripe under reclaim: !caching && injournal
4644 			 *
4645 			 * fall back to handle_stripe_dirtying()
4646 			 */
4647 			if (ret == -EAGAIN ||
4648 			    /* stripe under reclaim: !caching && injournal */
4649 			    (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
4650 			     s.injournal > 0)) {
4651 				ret = handle_stripe_dirtying(conf, sh, &s,
4652 							     disks);
4653 				if (ret == -EAGAIN)
4654 					goto finish;
4655 			}
4656 		}
4657 	}
4658 
4659 	/* maybe we need to check and possibly fix the parity for this stripe
4660 	 * Any reads will already have been scheduled, so we just see if enough
4661 	 * data is available.  The parity check is held off while parity
4662 	 * dependent operations are in flight.
4663 	 */
4664 	if (sh->check_state ||
4665 	    (s.syncing && s.locked == 0 &&
4666 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4667 	     !test_bit(STRIPE_INSYNC, &sh->state))) {
4668 		if (conf->level == 6)
4669 			handle_parity_checks6(conf, sh, &s, disks);
4670 		else
4671 			handle_parity_checks5(conf, sh, &s, disks);
4672 	}
4673 
4674 	if ((s.replacing || s.syncing) && s.locked == 0
4675 	    && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4676 	    && !test_bit(STRIPE_REPLACED, &sh->state)) {
4677 		/* Write out to replacement devices where possible */
4678 		for (i = 0; i < conf->raid_disks; i++)
4679 			if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4680 				WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4681 				set_bit(R5_WantReplace, &sh->dev[i].flags);
4682 				set_bit(R5_LOCKED, &sh->dev[i].flags);
4683 				s.locked++;
4684 			}
4685 		if (s.replacing)
4686 			set_bit(STRIPE_INSYNC, &sh->state);
4687 		set_bit(STRIPE_REPLACED, &sh->state);
4688 	}
4689 	if ((s.syncing || s.replacing) && s.locked == 0 &&
4690 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4691 	    test_bit(STRIPE_INSYNC, &sh->state)) {
4692 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4693 		clear_bit(STRIPE_SYNCING, &sh->state);
4694 		if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4695 			wake_up(&conf->wait_for_overlap);
4696 	}
4697 
4698 	/* If the failed drives are just a ReadError, then we might need
4699 	 * to progress the repair/check process
4700 	 */
4701 	if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4702 		for (i = 0; i < s.failed; i++) {
4703 			struct r5dev *dev = &sh->dev[s.failed_num[i]];
4704 			if (test_bit(R5_ReadError, &dev->flags)
4705 			    && !test_bit(R5_LOCKED, &dev->flags)
4706 			    && test_bit(R5_UPTODATE, &dev->flags)
4707 				) {
4708 				if (!test_bit(R5_ReWrite, &dev->flags)) {
4709 					set_bit(R5_Wantwrite, &dev->flags);
4710 					set_bit(R5_ReWrite, &dev->flags);
4711 					set_bit(R5_LOCKED, &dev->flags);
4712 					s.locked++;
4713 				} else {
4714 					/* let's read it back */
4715 					set_bit(R5_Wantread, &dev->flags);
4716 					set_bit(R5_LOCKED, &dev->flags);
4717 					s.locked++;
4718 				}
4719 			}
4720 		}
4721 
4722 	/* Finish reconstruct operations initiated by the expansion process */
4723 	if (sh->reconstruct_state == reconstruct_state_result) {
4724 		struct stripe_head *sh_src
4725 			= raid5_get_active_stripe(conf, sh->sector, 1, 1, 1);
4726 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4727 			/* sh cannot be written until sh_src has been read.
4728 			 * so arrange for sh to be delayed a little
4729 			 */
4730 			set_bit(STRIPE_DELAYED, &sh->state);
4731 			set_bit(STRIPE_HANDLE, &sh->state);
4732 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4733 					      &sh_src->state))
4734 				atomic_inc(&conf->preread_active_stripes);
4735 			raid5_release_stripe(sh_src);
4736 			goto finish;
4737 		}
4738 		if (sh_src)
4739 			raid5_release_stripe(sh_src);
4740 
4741 		sh->reconstruct_state = reconstruct_state_idle;
4742 		clear_bit(STRIPE_EXPANDING, &sh->state);
4743 		for (i = conf->raid_disks; i--; ) {
4744 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
4745 			set_bit(R5_LOCKED, &sh->dev[i].flags);
4746 			s.locked++;
4747 		}
4748 	}
4749 
4750 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4751 	    !sh->reconstruct_state) {
4752 		/* Need to write out all blocks after computing parity */
4753 		sh->disks = conf->raid_disks;
4754 		stripe_set_idx(sh->sector, conf, 0, sh);
4755 		schedule_reconstruction(sh, &s, 1, 1);
4756 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4757 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
4758 		atomic_dec(&conf->reshape_stripes);
4759 		wake_up(&conf->wait_for_overlap);
4760 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4761 	}
4762 
4763 	if (s.expanding && s.locked == 0 &&
4764 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4765 		handle_stripe_expansion(conf, sh);
4766 
4767 finish:
4768 	/* wait for this device to become unblocked */
4769 	if (unlikely(s.blocked_rdev)) {
4770 		if (conf->mddev->external)
4771 			md_wait_for_blocked_rdev(s.blocked_rdev,
4772 						 conf->mddev);
4773 		else
4774 			/* Internal metadata will immediately
4775 			 * be written by raid5d, so we don't
4776 			 * need to wait here.
4777 			 */
4778 			rdev_dec_pending(s.blocked_rdev,
4779 					 conf->mddev);
4780 	}
4781 
4782 	if (s.handle_bad_blocks)
4783 		for (i = disks; i--; ) {
4784 			struct md_rdev *rdev;
4785 			struct r5dev *dev = &sh->dev[i];
4786 			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4787 				/* We own a safe reference to the rdev */
4788 				rdev = conf->disks[i].rdev;
4789 				if (!rdev_set_badblocks(rdev, sh->sector,
4790 							STRIPE_SECTORS, 0))
4791 					md_error(conf->mddev, rdev);
4792 				rdev_dec_pending(rdev, conf->mddev);
4793 			}
4794 			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4795 				rdev = conf->disks[i].rdev;
4796 				rdev_clear_badblocks(rdev, sh->sector,
4797 						     STRIPE_SECTORS, 0);
4798 				rdev_dec_pending(rdev, conf->mddev);
4799 			}
4800 			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4801 				rdev = conf->disks[i].replacement;
4802 				if (!rdev)
4803 					/* rdev have been moved down */
4804 					rdev = conf->disks[i].rdev;
4805 				rdev_clear_badblocks(rdev, sh->sector,
4806 						     STRIPE_SECTORS, 0);
4807 				rdev_dec_pending(rdev, conf->mddev);
4808 			}
4809 		}
4810 
4811 	if (s.ops_request)
4812 		raid_run_ops(sh, s.ops_request);
4813 
4814 	ops_run_io(sh, &s);
4815 
4816 	if (s.dec_preread_active) {
4817 		/* We delay this until after ops_run_io so that if make_request
4818 		 * is waiting on a flush, it won't continue until the writes
4819 		 * have actually been submitted.
4820 		 */
4821 		atomic_dec(&conf->preread_active_stripes);
4822 		if (atomic_read(&conf->preread_active_stripes) <
4823 		    IO_THRESHOLD)
4824 			md_wakeup_thread(conf->mddev->thread);
4825 	}
4826 
4827 	if (!bio_list_empty(&s.return_bi)) {
4828 		if (test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) {
4829 			spin_lock_irq(&conf->device_lock);
4830 			bio_list_merge(&conf->return_bi, &s.return_bi);
4831 			spin_unlock_irq(&conf->device_lock);
4832 			md_wakeup_thread(conf->mddev->thread);
4833 		} else
4834 			return_io(&s.return_bi);
4835 	}
4836 
4837 	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4838 }
4839 
4840 static void raid5_activate_delayed(struct r5conf *conf)
4841 {
4842 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4843 		while (!list_empty(&conf->delayed_list)) {
4844 			struct list_head *l = conf->delayed_list.next;
4845 			struct stripe_head *sh;
4846 			sh = list_entry(l, struct stripe_head, lru);
4847 			list_del_init(l);
4848 			clear_bit(STRIPE_DELAYED, &sh->state);
4849 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4850 				atomic_inc(&conf->preread_active_stripes);
4851 			list_add_tail(&sh->lru, &conf->hold_list);
4852 			raid5_wakeup_stripe_thread(sh);
4853 		}
4854 	}
4855 }
4856 
4857 static void activate_bit_delay(struct r5conf *conf,
4858 	struct list_head *temp_inactive_list)
4859 {
4860 	/* device_lock is held */
4861 	struct list_head head;
4862 	list_add(&head, &conf->bitmap_list);
4863 	list_del_init(&conf->bitmap_list);
4864 	while (!list_empty(&head)) {
4865 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4866 		int hash;
4867 		list_del_init(&sh->lru);
4868 		atomic_inc(&sh->count);
4869 		hash = sh->hash_lock_index;
4870 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
4871 	}
4872 }
4873 
4874 static int raid5_congested(struct mddev *mddev, int bits)
4875 {
4876 	struct r5conf *conf = mddev->private;
4877 
4878 	/* No difference between reads and writes.  Just check
4879 	 * how busy the stripe_cache is
4880 	 */
4881 
4882 	if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
4883 		return 1;
4884 
4885 	/* Also checks whether there is pressure on r5cache log space */
4886 	if (test_bit(R5C_LOG_TIGHT, &conf->cache_state))
4887 		return 1;
4888 	if (conf->quiesce)
4889 		return 1;
4890 	if (atomic_read(&conf->empty_inactive_list_nr))
4891 		return 1;
4892 
4893 	return 0;
4894 }
4895 
4896 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4897 {
4898 	struct r5conf *conf = mddev->private;
4899 	sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4900 	unsigned int chunk_sectors;
4901 	unsigned int bio_sectors = bio_sectors(bio);
4902 
4903 	chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
4904 	return  chunk_sectors >=
4905 		((sector & (chunk_sectors - 1)) + bio_sectors);
4906 }
4907 
4908 /*
4909  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4910  *  later sampled by raid5d.
4911  */
4912 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4913 {
4914 	unsigned long flags;
4915 
4916 	spin_lock_irqsave(&conf->device_lock, flags);
4917 
4918 	bi->bi_next = conf->retry_read_aligned_list;
4919 	conf->retry_read_aligned_list = bi;
4920 
4921 	spin_unlock_irqrestore(&conf->device_lock, flags);
4922 	md_wakeup_thread(conf->mddev->thread);
4923 }
4924 
4925 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4926 {
4927 	struct bio *bi;
4928 
4929 	bi = conf->retry_read_aligned;
4930 	if (bi) {
4931 		conf->retry_read_aligned = NULL;
4932 		return bi;
4933 	}
4934 	bi = conf->retry_read_aligned_list;
4935 	if(bi) {
4936 		conf->retry_read_aligned_list = bi->bi_next;
4937 		bi->bi_next = NULL;
4938 		/*
4939 		 * this sets the active strip count to 1 and the processed
4940 		 * strip count to zero (upper 8 bits)
4941 		 */
4942 		raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
4943 	}
4944 
4945 	return bi;
4946 }
4947 
4948 /*
4949  *  The "raid5_align_endio" should check if the read succeeded and if it
4950  *  did, call bio_endio on the original bio (having bio_put the new bio
4951  *  first).
4952  *  If the read failed..
4953  */
4954 static void raid5_align_endio(struct bio *bi)
4955 {
4956 	struct bio* raid_bi  = bi->bi_private;
4957 	struct mddev *mddev;
4958 	struct r5conf *conf;
4959 	struct md_rdev *rdev;
4960 	int error = bi->bi_error;
4961 
4962 	bio_put(bi);
4963 
4964 	rdev = (void*)raid_bi->bi_next;
4965 	raid_bi->bi_next = NULL;
4966 	mddev = rdev->mddev;
4967 	conf = mddev->private;
4968 
4969 	rdev_dec_pending(rdev, conf->mddev);
4970 
4971 	if (!error) {
4972 		trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
4973 					 raid_bi, 0);
4974 		bio_endio(raid_bi);
4975 		if (atomic_dec_and_test(&conf->active_aligned_reads))
4976 			wake_up(&conf->wait_for_quiescent);
4977 		return;
4978 	}
4979 
4980 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
4981 
4982 	add_bio_to_retry(raid_bi, conf);
4983 }
4984 
4985 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
4986 {
4987 	struct r5conf *conf = mddev->private;
4988 	int dd_idx;
4989 	struct bio* align_bi;
4990 	struct md_rdev *rdev;
4991 	sector_t end_sector;
4992 
4993 	if (!in_chunk_boundary(mddev, raid_bio)) {
4994 		pr_debug("%s: non aligned\n", __func__);
4995 		return 0;
4996 	}
4997 	/*
4998 	 * use bio_clone_mddev to make a copy of the bio
4999 	 */
5000 	align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
5001 	if (!align_bi)
5002 		return 0;
5003 	/*
5004 	 *   set bi_end_io to a new function, and set bi_private to the
5005 	 *     original bio.
5006 	 */
5007 	align_bi->bi_end_io  = raid5_align_endio;
5008 	align_bi->bi_private = raid_bio;
5009 	/*
5010 	 *	compute position
5011 	 */
5012 	align_bi->bi_iter.bi_sector =
5013 		raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
5014 				     0, &dd_idx, NULL);
5015 
5016 	end_sector = bio_end_sector(align_bi);
5017 	rcu_read_lock();
5018 	rdev = rcu_dereference(conf->disks[dd_idx].replacement);
5019 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
5020 	    rdev->recovery_offset < end_sector) {
5021 		rdev = rcu_dereference(conf->disks[dd_idx].rdev);
5022 		if (rdev &&
5023 		    (test_bit(Faulty, &rdev->flags) ||
5024 		    !(test_bit(In_sync, &rdev->flags) ||
5025 		      rdev->recovery_offset >= end_sector)))
5026 			rdev = NULL;
5027 	}
5028 	if (rdev) {
5029 		sector_t first_bad;
5030 		int bad_sectors;
5031 
5032 		atomic_inc(&rdev->nr_pending);
5033 		rcu_read_unlock();
5034 		raid_bio->bi_next = (void*)rdev;
5035 		align_bi->bi_bdev =  rdev->bdev;
5036 		bio_clear_flag(align_bi, BIO_SEG_VALID);
5037 
5038 		if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
5039 				bio_sectors(align_bi),
5040 				&first_bad, &bad_sectors)) {
5041 			bio_put(align_bi);
5042 			rdev_dec_pending(rdev, mddev);
5043 			return 0;
5044 		}
5045 
5046 		/* No reshape active, so we can trust rdev->data_offset */
5047 		align_bi->bi_iter.bi_sector += rdev->data_offset;
5048 
5049 		spin_lock_irq(&conf->device_lock);
5050 		wait_event_lock_irq(conf->wait_for_quiescent,
5051 				    conf->quiesce == 0,
5052 				    conf->device_lock);
5053 		atomic_inc(&conf->active_aligned_reads);
5054 		spin_unlock_irq(&conf->device_lock);
5055 
5056 		if (mddev->gendisk)
5057 			trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
5058 					      align_bi, disk_devt(mddev->gendisk),
5059 					      raid_bio->bi_iter.bi_sector);
5060 		generic_make_request(align_bi);
5061 		return 1;
5062 	} else {
5063 		rcu_read_unlock();
5064 		bio_put(align_bi);
5065 		return 0;
5066 	}
5067 }
5068 
5069 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
5070 {
5071 	struct bio *split;
5072 
5073 	do {
5074 		sector_t sector = raid_bio->bi_iter.bi_sector;
5075 		unsigned chunk_sects = mddev->chunk_sectors;
5076 		unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
5077 
5078 		if (sectors < bio_sectors(raid_bio)) {
5079 			split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);
5080 			bio_chain(split, raid_bio);
5081 		} else
5082 			split = raid_bio;
5083 
5084 		if (!raid5_read_one_chunk(mddev, split)) {
5085 			if (split != raid_bio)
5086 				generic_make_request(raid_bio);
5087 			return split;
5088 		}
5089 	} while (split != raid_bio);
5090 
5091 	return NULL;
5092 }
5093 
5094 /* __get_priority_stripe - get the next stripe to process
5095  *
5096  * Full stripe writes are allowed to pass preread active stripes up until
5097  * the bypass_threshold is exceeded.  In general the bypass_count
5098  * increments when the handle_list is handled before the hold_list; however, it
5099  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
5100  * stripe with in flight i/o.  The bypass_count will be reset when the
5101  * head of the hold_list has changed, i.e. the head was promoted to the
5102  * handle_list.
5103  */
5104 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
5105 {
5106 	struct stripe_head *sh = NULL, *tmp;
5107 	struct list_head *handle_list = NULL;
5108 	struct r5worker_group *wg = NULL;
5109 
5110 	if (conf->worker_cnt_per_group == 0) {
5111 		handle_list = &conf->handle_list;
5112 	} else if (group != ANY_GROUP) {
5113 		handle_list = &conf->worker_groups[group].handle_list;
5114 		wg = &conf->worker_groups[group];
5115 	} else {
5116 		int i;
5117 		for (i = 0; i < conf->group_cnt; i++) {
5118 			handle_list = &conf->worker_groups[i].handle_list;
5119 			wg = &conf->worker_groups[i];
5120 			if (!list_empty(handle_list))
5121 				break;
5122 		}
5123 	}
5124 
5125 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
5126 		  __func__,
5127 		  list_empty(handle_list) ? "empty" : "busy",
5128 		  list_empty(&conf->hold_list) ? "empty" : "busy",
5129 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
5130 
5131 	if (!list_empty(handle_list)) {
5132 		sh = list_entry(handle_list->next, typeof(*sh), lru);
5133 
5134 		if (list_empty(&conf->hold_list))
5135 			conf->bypass_count = 0;
5136 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
5137 			if (conf->hold_list.next == conf->last_hold)
5138 				conf->bypass_count++;
5139 			else {
5140 				conf->last_hold = conf->hold_list.next;
5141 				conf->bypass_count -= conf->bypass_threshold;
5142 				if (conf->bypass_count < 0)
5143 					conf->bypass_count = 0;
5144 			}
5145 		}
5146 	} else if (!list_empty(&conf->hold_list) &&
5147 		   ((conf->bypass_threshold &&
5148 		     conf->bypass_count > conf->bypass_threshold) ||
5149 		    atomic_read(&conf->pending_full_writes) == 0)) {
5150 
5151 		list_for_each_entry(tmp, &conf->hold_list,  lru) {
5152 			if (conf->worker_cnt_per_group == 0 ||
5153 			    group == ANY_GROUP ||
5154 			    !cpu_online(tmp->cpu) ||
5155 			    cpu_to_group(tmp->cpu) == group) {
5156 				sh = tmp;
5157 				break;
5158 			}
5159 		}
5160 
5161 		if (sh) {
5162 			conf->bypass_count -= conf->bypass_threshold;
5163 			if (conf->bypass_count < 0)
5164 				conf->bypass_count = 0;
5165 		}
5166 		wg = NULL;
5167 	}
5168 
5169 	if (!sh)
5170 		return NULL;
5171 
5172 	if (wg) {
5173 		wg->stripes_cnt--;
5174 		sh->group = NULL;
5175 	}
5176 	list_del_init(&sh->lru);
5177 	BUG_ON(atomic_inc_return(&sh->count) != 1);
5178 	return sh;
5179 }
5180 
5181 struct raid5_plug_cb {
5182 	struct blk_plug_cb	cb;
5183 	struct list_head	list;
5184 	struct list_head	temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5185 };
5186 
5187 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5188 {
5189 	struct raid5_plug_cb *cb = container_of(
5190 		blk_cb, struct raid5_plug_cb, cb);
5191 	struct stripe_head *sh;
5192 	struct mddev *mddev = cb->cb.data;
5193 	struct r5conf *conf = mddev->private;
5194 	int cnt = 0;
5195 	int hash;
5196 
5197 	if (cb->list.next && !list_empty(&cb->list)) {
5198 		spin_lock_irq(&conf->device_lock);
5199 		while (!list_empty(&cb->list)) {
5200 			sh = list_first_entry(&cb->list, struct stripe_head, lru);
5201 			list_del_init(&sh->lru);
5202 			/*
5203 			 * avoid race release_stripe_plug() sees
5204 			 * STRIPE_ON_UNPLUG_LIST clear but the stripe
5205 			 * is still in our list
5206 			 */
5207 			smp_mb__before_atomic();
5208 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5209 			/*
5210 			 * STRIPE_ON_RELEASE_LIST could be set here. In that
5211 			 * case, the count is always > 1 here
5212 			 */
5213 			hash = sh->hash_lock_index;
5214 			__release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5215 			cnt++;
5216 		}
5217 		spin_unlock_irq(&conf->device_lock);
5218 	}
5219 	release_inactive_stripe_list(conf, cb->temp_inactive_list,
5220 				     NR_STRIPE_HASH_LOCKS);
5221 	if (mddev->queue)
5222 		trace_block_unplug(mddev->queue, cnt, !from_schedule);
5223 	kfree(cb);
5224 }
5225 
5226 static void release_stripe_plug(struct mddev *mddev,
5227 				struct stripe_head *sh)
5228 {
5229 	struct blk_plug_cb *blk_cb = blk_check_plugged(
5230 		raid5_unplug, mddev,
5231 		sizeof(struct raid5_plug_cb));
5232 	struct raid5_plug_cb *cb;
5233 
5234 	if (!blk_cb) {
5235 		raid5_release_stripe(sh);
5236 		return;
5237 	}
5238 
5239 	cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5240 
5241 	if (cb->list.next == NULL) {
5242 		int i;
5243 		INIT_LIST_HEAD(&cb->list);
5244 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5245 			INIT_LIST_HEAD(cb->temp_inactive_list + i);
5246 	}
5247 
5248 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5249 		list_add_tail(&sh->lru, &cb->list);
5250 	else
5251 		raid5_release_stripe(sh);
5252 }
5253 
5254 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5255 {
5256 	struct r5conf *conf = mddev->private;
5257 	sector_t logical_sector, last_sector;
5258 	struct stripe_head *sh;
5259 	int remaining;
5260 	int stripe_sectors;
5261 
5262 	if (mddev->reshape_position != MaxSector)
5263 		/* Skip discard while reshape is happening */
5264 		return;
5265 
5266 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5267 	last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5268 
5269 	bi->bi_next = NULL;
5270 	bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
5271 
5272 	stripe_sectors = conf->chunk_sectors *
5273 		(conf->raid_disks - conf->max_degraded);
5274 	logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5275 					       stripe_sectors);
5276 	sector_div(last_sector, stripe_sectors);
5277 
5278 	logical_sector *= conf->chunk_sectors;
5279 	last_sector *= conf->chunk_sectors;
5280 
5281 	for (; logical_sector < last_sector;
5282 	     logical_sector += STRIPE_SECTORS) {
5283 		DEFINE_WAIT(w);
5284 		int d;
5285 	again:
5286 		sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
5287 		prepare_to_wait(&conf->wait_for_overlap, &w,
5288 				TASK_UNINTERRUPTIBLE);
5289 		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5290 		if (test_bit(STRIPE_SYNCING, &sh->state)) {
5291 			raid5_release_stripe(sh);
5292 			schedule();
5293 			goto again;
5294 		}
5295 		clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5296 		spin_lock_irq(&sh->stripe_lock);
5297 		for (d = 0; d < conf->raid_disks; d++) {
5298 			if (d == sh->pd_idx || d == sh->qd_idx)
5299 				continue;
5300 			if (sh->dev[d].towrite || sh->dev[d].toread) {
5301 				set_bit(R5_Overlap, &sh->dev[d].flags);
5302 				spin_unlock_irq(&sh->stripe_lock);
5303 				raid5_release_stripe(sh);
5304 				schedule();
5305 				goto again;
5306 			}
5307 		}
5308 		set_bit(STRIPE_DISCARD, &sh->state);
5309 		finish_wait(&conf->wait_for_overlap, &w);
5310 		sh->overwrite_disks = 0;
5311 		for (d = 0; d < conf->raid_disks; d++) {
5312 			if (d == sh->pd_idx || d == sh->qd_idx)
5313 				continue;
5314 			sh->dev[d].towrite = bi;
5315 			set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5316 			raid5_inc_bi_active_stripes(bi);
5317 			sh->overwrite_disks++;
5318 		}
5319 		spin_unlock_irq(&sh->stripe_lock);
5320 		if (conf->mddev->bitmap) {
5321 			for (d = 0;
5322 			     d < conf->raid_disks - conf->max_degraded;
5323 			     d++)
5324 				bitmap_startwrite(mddev->bitmap,
5325 						  sh->sector,
5326 						  STRIPE_SECTORS,
5327 						  0);
5328 			sh->bm_seq = conf->seq_flush + 1;
5329 			set_bit(STRIPE_BIT_DELAY, &sh->state);
5330 		}
5331 
5332 		set_bit(STRIPE_HANDLE, &sh->state);
5333 		clear_bit(STRIPE_DELAYED, &sh->state);
5334 		if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5335 			atomic_inc(&conf->preread_active_stripes);
5336 		release_stripe_plug(mddev, sh);
5337 	}
5338 
5339 	remaining = raid5_dec_bi_active_stripes(bi);
5340 	if (remaining == 0) {
5341 		md_write_end(mddev);
5342 		bio_endio(bi);
5343 	}
5344 }
5345 
5346 static void raid5_make_request(struct mddev *mddev, struct bio * bi)
5347 {
5348 	struct r5conf *conf = mddev->private;
5349 	int dd_idx;
5350 	sector_t new_sector;
5351 	sector_t logical_sector, last_sector;
5352 	struct stripe_head *sh;
5353 	const int rw = bio_data_dir(bi);
5354 	int remaining;
5355 	DEFINE_WAIT(w);
5356 	bool do_prepare;
5357 	bool do_flush = false;
5358 
5359 	if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
5360 		int ret = r5l_handle_flush_request(conf->log, bi);
5361 
5362 		if (ret == 0)
5363 			return;
5364 		if (ret == -ENODEV) {
5365 			md_flush_request(mddev, bi);
5366 			return;
5367 		}
5368 		/* ret == -EAGAIN, fallback */
5369 		/*
5370 		 * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
5371 		 * we need to flush journal device
5372 		 */
5373 		do_flush = bi->bi_opf & REQ_PREFLUSH;
5374 	}
5375 
5376 	md_write_start(mddev, bi);
5377 
5378 	/*
5379 	 * If array is degraded, better not do chunk aligned read because
5380 	 * later we might have to read it again in order to reconstruct
5381 	 * data on failed drives.
5382 	 */
5383 	if (rw == READ && mddev->degraded == 0 &&
5384 	    !r5c_is_writeback(conf->log) &&
5385 	    mddev->reshape_position == MaxSector) {
5386 		bi = chunk_aligned_read(mddev, bi);
5387 		if (!bi)
5388 			return;
5389 	}
5390 
5391 	if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) {
5392 		make_discard_request(mddev, bi);
5393 		return;
5394 	}
5395 
5396 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5397 	last_sector = bio_end_sector(bi);
5398 	bi->bi_next = NULL;
5399 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
5400 
5401 	prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5402 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5403 		int previous;
5404 		int seq;
5405 
5406 		do_prepare = false;
5407 	retry:
5408 		seq = read_seqcount_begin(&conf->gen_lock);
5409 		previous = 0;
5410 		if (do_prepare)
5411 			prepare_to_wait(&conf->wait_for_overlap, &w,
5412 				TASK_UNINTERRUPTIBLE);
5413 		if (unlikely(conf->reshape_progress != MaxSector)) {
5414 			/* spinlock is needed as reshape_progress may be
5415 			 * 64bit on a 32bit platform, and so it might be
5416 			 * possible to see a half-updated value
5417 			 * Of course reshape_progress could change after
5418 			 * the lock is dropped, so once we get a reference
5419 			 * to the stripe that we think it is, we will have
5420 			 * to check again.
5421 			 */
5422 			spin_lock_irq(&conf->device_lock);
5423 			if (mddev->reshape_backwards
5424 			    ? logical_sector < conf->reshape_progress
5425 			    : logical_sector >= conf->reshape_progress) {
5426 				previous = 1;
5427 			} else {
5428 				if (mddev->reshape_backwards
5429 				    ? logical_sector < conf->reshape_safe
5430 				    : logical_sector >= conf->reshape_safe) {
5431 					spin_unlock_irq(&conf->device_lock);
5432 					schedule();
5433 					do_prepare = true;
5434 					goto retry;
5435 				}
5436 			}
5437 			spin_unlock_irq(&conf->device_lock);
5438 		}
5439 
5440 		new_sector = raid5_compute_sector(conf, logical_sector,
5441 						  previous,
5442 						  &dd_idx, NULL);
5443 		pr_debug("raid456: raid5_make_request, sector %llu logical %llu\n",
5444 			(unsigned long long)new_sector,
5445 			(unsigned long long)logical_sector);
5446 
5447 		sh = raid5_get_active_stripe(conf, new_sector, previous,
5448 				       (bi->bi_opf & REQ_RAHEAD), 0);
5449 		if (sh) {
5450 			if (unlikely(previous)) {
5451 				/* expansion might have moved on while waiting for a
5452 				 * stripe, so we must do the range check again.
5453 				 * Expansion could still move past after this
5454 				 * test, but as we are holding a reference to
5455 				 * 'sh', we know that if that happens,
5456 				 *  STRIPE_EXPANDING will get set and the expansion
5457 				 * won't proceed until we finish with the stripe.
5458 				 */
5459 				int must_retry = 0;
5460 				spin_lock_irq(&conf->device_lock);
5461 				if (mddev->reshape_backwards
5462 				    ? logical_sector >= conf->reshape_progress
5463 				    : logical_sector < conf->reshape_progress)
5464 					/* mismatch, need to try again */
5465 					must_retry = 1;
5466 				spin_unlock_irq(&conf->device_lock);
5467 				if (must_retry) {
5468 					raid5_release_stripe(sh);
5469 					schedule();
5470 					do_prepare = true;
5471 					goto retry;
5472 				}
5473 			}
5474 			if (read_seqcount_retry(&conf->gen_lock, seq)) {
5475 				/* Might have got the wrong stripe_head
5476 				 * by accident
5477 				 */
5478 				raid5_release_stripe(sh);
5479 				goto retry;
5480 			}
5481 
5482 			if (rw == WRITE &&
5483 			    logical_sector >= mddev->suspend_lo &&
5484 			    logical_sector < mddev->suspend_hi) {
5485 				raid5_release_stripe(sh);
5486 				/* As the suspend_* range is controlled by
5487 				 * userspace, we want an interruptible
5488 				 * wait.
5489 				 */
5490 				flush_signals(current);
5491 				prepare_to_wait(&conf->wait_for_overlap,
5492 						&w, TASK_INTERRUPTIBLE);
5493 				if (logical_sector >= mddev->suspend_lo &&
5494 				    logical_sector < mddev->suspend_hi) {
5495 					schedule();
5496 					do_prepare = true;
5497 				}
5498 				goto retry;
5499 			}
5500 
5501 			if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5502 			    !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5503 				/* Stripe is busy expanding or
5504 				 * add failed due to overlap.  Flush everything
5505 				 * and wait a while
5506 				 */
5507 				md_wakeup_thread(mddev->thread);
5508 				raid5_release_stripe(sh);
5509 				schedule();
5510 				do_prepare = true;
5511 				goto retry;
5512 			}
5513 			if (do_flush) {
5514 				set_bit(STRIPE_R5C_PREFLUSH, &sh->state);
5515 				/* we only need flush for one stripe */
5516 				do_flush = false;
5517 			}
5518 
5519 			set_bit(STRIPE_HANDLE, &sh->state);
5520 			clear_bit(STRIPE_DELAYED, &sh->state);
5521 			if ((!sh->batch_head || sh == sh->batch_head) &&
5522 			    (bi->bi_opf & REQ_SYNC) &&
5523 			    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5524 				atomic_inc(&conf->preread_active_stripes);
5525 			release_stripe_plug(mddev, sh);
5526 		} else {
5527 			/* cannot get stripe for read-ahead, just give-up */
5528 			bi->bi_error = -EIO;
5529 			break;
5530 		}
5531 	}
5532 	finish_wait(&conf->wait_for_overlap, &w);
5533 
5534 	remaining = raid5_dec_bi_active_stripes(bi);
5535 	if (remaining == 0) {
5536 
5537 		if ( rw == WRITE )
5538 			md_write_end(mddev);
5539 
5540 		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
5541 					 bi, 0);
5542 		bio_endio(bi);
5543 	}
5544 }
5545 
5546 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5547 
5548 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5549 {
5550 	/* reshaping is quite different to recovery/resync so it is
5551 	 * handled quite separately ... here.
5552 	 *
5553 	 * On each call to sync_request, we gather one chunk worth of
5554 	 * destination stripes and flag them as expanding.
5555 	 * Then we find all the source stripes and request reads.
5556 	 * As the reads complete, handle_stripe will copy the data
5557 	 * into the destination stripe and release that stripe.
5558 	 */
5559 	struct r5conf *conf = mddev->private;
5560 	struct stripe_head *sh;
5561 	sector_t first_sector, last_sector;
5562 	int raid_disks = conf->previous_raid_disks;
5563 	int data_disks = raid_disks - conf->max_degraded;
5564 	int new_data_disks = conf->raid_disks - conf->max_degraded;
5565 	int i;
5566 	int dd_idx;
5567 	sector_t writepos, readpos, safepos;
5568 	sector_t stripe_addr;
5569 	int reshape_sectors;
5570 	struct list_head stripes;
5571 	sector_t retn;
5572 
5573 	if (sector_nr == 0) {
5574 		/* If restarting in the middle, skip the initial sectors */
5575 		if (mddev->reshape_backwards &&
5576 		    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5577 			sector_nr = raid5_size(mddev, 0, 0)
5578 				- conf->reshape_progress;
5579 		} else if (mddev->reshape_backwards &&
5580 			   conf->reshape_progress == MaxSector) {
5581 			/* shouldn't happen, but just in case, finish up.*/
5582 			sector_nr = MaxSector;
5583 		} else if (!mddev->reshape_backwards &&
5584 			   conf->reshape_progress > 0)
5585 			sector_nr = conf->reshape_progress;
5586 		sector_div(sector_nr, new_data_disks);
5587 		if (sector_nr) {
5588 			mddev->curr_resync_completed = sector_nr;
5589 			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5590 			*skipped = 1;
5591 			retn = sector_nr;
5592 			goto finish;
5593 		}
5594 	}
5595 
5596 	/* We need to process a full chunk at a time.
5597 	 * If old and new chunk sizes differ, we need to process the
5598 	 * largest of these
5599 	 */
5600 
5601 	reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
5602 
5603 	/* We update the metadata at least every 10 seconds, or when
5604 	 * the data about to be copied would over-write the source of
5605 	 * the data at the front of the range.  i.e. one new_stripe
5606 	 * along from reshape_progress new_maps to after where
5607 	 * reshape_safe old_maps to
5608 	 */
5609 	writepos = conf->reshape_progress;
5610 	sector_div(writepos, new_data_disks);
5611 	readpos = conf->reshape_progress;
5612 	sector_div(readpos, data_disks);
5613 	safepos = conf->reshape_safe;
5614 	sector_div(safepos, data_disks);
5615 	if (mddev->reshape_backwards) {
5616 		BUG_ON(writepos < reshape_sectors);
5617 		writepos -= reshape_sectors;
5618 		readpos += reshape_sectors;
5619 		safepos += reshape_sectors;
5620 	} else {
5621 		writepos += reshape_sectors;
5622 		/* readpos and safepos are worst-case calculations.
5623 		 * A negative number is overly pessimistic, and causes
5624 		 * obvious problems for unsigned storage.  So clip to 0.
5625 		 */
5626 		readpos -= min_t(sector_t, reshape_sectors, readpos);
5627 		safepos -= min_t(sector_t, reshape_sectors, safepos);
5628 	}
5629 
5630 	/* Having calculated the 'writepos' possibly use it
5631 	 * to set 'stripe_addr' which is where we will write to.
5632 	 */
5633 	if (mddev->reshape_backwards) {
5634 		BUG_ON(conf->reshape_progress == 0);
5635 		stripe_addr = writepos;
5636 		BUG_ON((mddev->dev_sectors &
5637 			~((sector_t)reshape_sectors - 1))
5638 		       - reshape_sectors - stripe_addr
5639 		       != sector_nr);
5640 	} else {
5641 		BUG_ON(writepos != sector_nr + reshape_sectors);
5642 		stripe_addr = sector_nr;
5643 	}
5644 
5645 	/* 'writepos' is the most advanced device address we might write.
5646 	 * 'readpos' is the least advanced device address we might read.
5647 	 * 'safepos' is the least address recorded in the metadata as having
5648 	 *     been reshaped.
5649 	 * If there is a min_offset_diff, these are adjusted either by
5650 	 * increasing the safepos/readpos if diff is negative, or
5651 	 * increasing writepos if diff is positive.
5652 	 * If 'readpos' is then behind 'writepos', there is no way that we can
5653 	 * ensure safety in the face of a crash - that must be done by userspace
5654 	 * making a backup of the data.  So in that case there is no particular
5655 	 * rush to update metadata.
5656 	 * Otherwise if 'safepos' is behind 'writepos', then we really need to
5657 	 * update the metadata to advance 'safepos' to match 'readpos' so that
5658 	 * we can be safe in the event of a crash.
5659 	 * So we insist on updating metadata if safepos is behind writepos and
5660 	 * readpos is beyond writepos.
5661 	 * In any case, update the metadata every 10 seconds.
5662 	 * Maybe that number should be configurable, but I'm not sure it is
5663 	 * worth it.... maybe it could be a multiple of safemode_delay???
5664 	 */
5665 	if (conf->min_offset_diff < 0) {
5666 		safepos += -conf->min_offset_diff;
5667 		readpos += -conf->min_offset_diff;
5668 	} else
5669 		writepos += conf->min_offset_diff;
5670 
5671 	if ((mddev->reshape_backwards
5672 	     ? (safepos > writepos && readpos < writepos)
5673 	     : (safepos < writepos && readpos > writepos)) ||
5674 	    time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5675 		/* Cannot proceed until we've updated the superblock... */
5676 		wait_event(conf->wait_for_overlap,
5677 			   atomic_read(&conf->reshape_stripes)==0
5678 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5679 		if (atomic_read(&conf->reshape_stripes) != 0)
5680 			return 0;
5681 		mddev->reshape_position = conf->reshape_progress;
5682 		mddev->curr_resync_completed = sector_nr;
5683 		conf->reshape_checkpoint = jiffies;
5684 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5685 		md_wakeup_thread(mddev->thread);
5686 		wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
5687 			   test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5688 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5689 			return 0;
5690 		spin_lock_irq(&conf->device_lock);
5691 		conf->reshape_safe = mddev->reshape_position;
5692 		spin_unlock_irq(&conf->device_lock);
5693 		wake_up(&conf->wait_for_overlap);
5694 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5695 	}
5696 
5697 	INIT_LIST_HEAD(&stripes);
5698 	for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5699 		int j;
5700 		int skipped_disk = 0;
5701 		sh = raid5_get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5702 		set_bit(STRIPE_EXPANDING, &sh->state);
5703 		atomic_inc(&conf->reshape_stripes);
5704 		/* If any of this stripe is beyond the end of the old
5705 		 * array, then we need to zero those blocks
5706 		 */
5707 		for (j=sh->disks; j--;) {
5708 			sector_t s;
5709 			if (j == sh->pd_idx)
5710 				continue;
5711 			if (conf->level == 6 &&
5712 			    j == sh->qd_idx)
5713 				continue;
5714 			s = raid5_compute_blocknr(sh, j, 0);
5715 			if (s < raid5_size(mddev, 0, 0)) {
5716 				skipped_disk = 1;
5717 				continue;
5718 			}
5719 			memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5720 			set_bit(R5_Expanded, &sh->dev[j].flags);
5721 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
5722 		}
5723 		if (!skipped_disk) {
5724 			set_bit(STRIPE_EXPAND_READY, &sh->state);
5725 			set_bit(STRIPE_HANDLE, &sh->state);
5726 		}
5727 		list_add(&sh->lru, &stripes);
5728 	}
5729 	spin_lock_irq(&conf->device_lock);
5730 	if (mddev->reshape_backwards)
5731 		conf->reshape_progress -= reshape_sectors * new_data_disks;
5732 	else
5733 		conf->reshape_progress += reshape_sectors * new_data_disks;
5734 	spin_unlock_irq(&conf->device_lock);
5735 	/* Ok, those stripe are ready. We can start scheduling
5736 	 * reads on the source stripes.
5737 	 * The source stripes are determined by mapping the first and last
5738 	 * block on the destination stripes.
5739 	 */
5740 	first_sector =
5741 		raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5742 				     1, &dd_idx, NULL);
5743 	last_sector =
5744 		raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5745 					    * new_data_disks - 1),
5746 				     1, &dd_idx, NULL);
5747 	if (last_sector >= mddev->dev_sectors)
5748 		last_sector = mddev->dev_sectors - 1;
5749 	while (first_sector <= last_sector) {
5750 		sh = raid5_get_active_stripe(conf, first_sector, 1, 0, 1);
5751 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5752 		set_bit(STRIPE_HANDLE, &sh->state);
5753 		raid5_release_stripe(sh);
5754 		first_sector += STRIPE_SECTORS;
5755 	}
5756 	/* Now that the sources are clearly marked, we can release
5757 	 * the destination stripes
5758 	 */
5759 	while (!list_empty(&stripes)) {
5760 		sh = list_entry(stripes.next, struct stripe_head, lru);
5761 		list_del_init(&sh->lru);
5762 		raid5_release_stripe(sh);
5763 	}
5764 	/* If this takes us to the resync_max point where we have to pause,
5765 	 * then we need to write out the superblock.
5766 	 */
5767 	sector_nr += reshape_sectors;
5768 	retn = reshape_sectors;
5769 finish:
5770 	if (mddev->curr_resync_completed > mddev->resync_max ||
5771 	    (sector_nr - mddev->curr_resync_completed) * 2
5772 	    >= mddev->resync_max - mddev->curr_resync_completed) {
5773 		/* Cannot proceed until we've updated the superblock... */
5774 		wait_event(conf->wait_for_overlap,
5775 			   atomic_read(&conf->reshape_stripes) == 0
5776 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5777 		if (atomic_read(&conf->reshape_stripes) != 0)
5778 			goto ret;
5779 		mddev->reshape_position = conf->reshape_progress;
5780 		mddev->curr_resync_completed = sector_nr;
5781 		conf->reshape_checkpoint = jiffies;
5782 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5783 		md_wakeup_thread(mddev->thread);
5784 		wait_event(mddev->sb_wait,
5785 			   !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)
5786 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5787 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5788 			goto ret;
5789 		spin_lock_irq(&conf->device_lock);
5790 		conf->reshape_safe = mddev->reshape_position;
5791 		spin_unlock_irq(&conf->device_lock);
5792 		wake_up(&conf->wait_for_overlap);
5793 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5794 	}
5795 ret:
5796 	return retn;
5797 }
5798 
5799 static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_nr,
5800 					  int *skipped)
5801 {
5802 	struct r5conf *conf = mddev->private;
5803 	struct stripe_head *sh;
5804 	sector_t max_sector = mddev->dev_sectors;
5805 	sector_t sync_blocks;
5806 	int still_degraded = 0;
5807 	int i;
5808 
5809 	if (sector_nr >= max_sector) {
5810 		/* just being told to finish up .. nothing much to do */
5811 
5812 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5813 			end_reshape(conf);
5814 			return 0;
5815 		}
5816 
5817 		if (mddev->curr_resync < max_sector) /* aborted */
5818 			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5819 					&sync_blocks, 1);
5820 		else /* completed sync */
5821 			conf->fullsync = 0;
5822 		bitmap_close_sync(mddev->bitmap);
5823 
5824 		return 0;
5825 	}
5826 
5827 	/* Allow raid5_quiesce to complete */
5828 	wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5829 
5830 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5831 		return reshape_request(mddev, sector_nr, skipped);
5832 
5833 	/* No need to check resync_max as we never do more than one
5834 	 * stripe, and as resync_max will always be on a chunk boundary,
5835 	 * if the check in md_do_sync didn't fire, there is no chance
5836 	 * of overstepping resync_max here
5837 	 */
5838 
5839 	/* if there is too many failed drives and we are trying
5840 	 * to resync, then assert that we are finished, because there is
5841 	 * nothing we can do.
5842 	 */
5843 	if (mddev->degraded >= conf->max_degraded &&
5844 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5845 		sector_t rv = mddev->dev_sectors - sector_nr;
5846 		*skipped = 1;
5847 		return rv;
5848 	}
5849 	if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5850 	    !conf->fullsync &&
5851 	    !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5852 	    sync_blocks >= STRIPE_SECTORS) {
5853 		/* we can skip this block, and probably more */
5854 		sync_blocks /= STRIPE_SECTORS;
5855 		*skipped = 1;
5856 		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5857 	}
5858 
5859 	bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
5860 
5861 	sh = raid5_get_active_stripe(conf, sector_nr, 0, 1, 0);
5862 	if (sh == NULL) {
5863 		sh = raid5_get_active_stripe(conf, sector_nr, 0, 0, 0);
5864 		/* make sure we don't swamp the stripe cache if someone else
5865 		 * is trying to get access
5866 		 */
5867 		schedule_timeout_uninterruptible(1);
5868 	}
5869 	/* Need to check if array will still be degraded after recovery/resync
5870 	 * Note in case of > 1 drive failures it's possible we're rebuilding
5871 	 * one drive while leaving another faulty drive in array.
5872 	 */
5873 	rcu_read_lock();
5874 	for (i = 0; i < conf->raid_disks; i++) {
5875 		struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
5876 
5877 		if (rdev == NULL || test_bit(Faulty, &rdev->flags))
5878 			still_degraded = 1;
5879 	}
5880 	rcu_read_unlock();
5881 
5882 	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5883 
5884 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5885 	set_bit(STRIPE_HANDLE, &sh->state);
5886 
5887 	raid5_release_stripe(sh);
5888 
5889 	return STRIPE_SECTORS;
5890 }
5891 
5892 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5893 {
5894 	/* We may not be able to submit a whole bio at once as there
5895 	 * may not be enough stripe_heads available.
5896 	 * We cannot pre-allocate enough stripe_heads as we may need
5897 	 * more than exist in the cache (if we allow ever large chunks).
5898 	 * So we do one stripe head at a time and record in
5899 	 * ->bi_hw_segments how many have been done.
5900 	 *
5901 	 * We *know* that this entire raid_bio is in one chunk, so
5902 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5903 	 */
5904 	struct stripe_head *sh;
5905 	int dd_idx;
5906 	sector_t sector, logical_sector, last_sector;
5907 	int scnt = 0;
5908 	int remaining;
5909 	int handled = 0;
5910 
5911 	logical_sector = raid_bio->bi_iter.bi_sector &
5912 		~((sector_t)STRIPE_SECTORS-1);
5913 	sector = raid5_compute_sector(conf, logical_sector,
5914 				      0, &dd_idx, NULL);
5915 	last_sector = bio_end_sector(raid_bio);
5916 
5917 	for (; logical_sector < last_sector;
5918 	     logical_sector += STRIPE_SECTORS,
5919 		     sector += STRIPE_SECTORS,
5920 		     scnt++) {
5921 
5922 		if (scnt < raid5_bi_processed_stripes(raid_bio))
5923 			/* already done this stripe */
5924 			continue;
5925 
5926 		sh = raid5_get_active_stripe(conf, sector, 0, 1, 1);
5927 
5928 		if (!sh) {
5929 			/* failed to get a stripe - must wait */
5930 			raid5_set_bi_processed_stripes(raid_bio, scnt);
5931 			conf->retry_read_aligned = raid_bio;
5932 			return handled;
5933 		}
5934 
5935 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
5936 			raid5_release_stripe(sh);
5937 			raid5_set_bi_processed_stripes(raid_bio, scnt);
5938 			conf->retry_read_aligned = raid_bio;
5939 			return handled;
5940 		}
5941 
5942 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
5943 		handle_stripe(sh);
5944 		raid5_release_stripe(sh);
5945 		handled++;
5946 	}
5947 	remaining = raid5_dec_bi_active_stripes(raid_bio);
5948 	if (remaining == 0) {
5949 		trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
5950 					 raid_bio, 0);
5951 		bio_endio(raid_bio);
5952 	}
5953 	if (atomic_dec_and_test(&conf->active_aligned_reads))
5954 		wake_up(&conf->wait_for_quiescent);
5955 	return handled;
5956 }
5957 
5958 static int handle_active_stripes(struct r5conf *conf, int group,
5959 				 struct r5worker *worker,
5960 				 struct list_head *temp_inactive_list)
5961 {
5962 	struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
5963 	int i, batch_size = 0, hash;
5964 	bool release_inactive = false;
5965 
5966 	while (batch_size < MAX_STRIPE_BATCH &&
5967 			(sh = __get_priority_stripe(conf, group)) != NULL)
5968 		batch[batch_size++] = sh;
5969 
5970 	if (batch_size == 0) {
5971 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5972 			if (!list_empty(temp_inactive_list + i))
5973 				break;
5974 		if (i == NR_STRIPE_HASH_LOCKS) {
5975 			spin_unlock_irq(&conf->device_lock);
5976 			r5l_flush_stripe_to_raid(conf->log);
5977 			spin_lock_irq(&conf->device_lock);
5978 			return batch_size;
5979 		}
5980 		release_inactive = true;
5981 	}
5982 	spin_unlock_irq(&conf->device_lock);
5983 
5984 	release_inactive_stripe_list(conf, temp_inactive_list,
5985 				     NR_STRIPE_HASH_LOCKS);
5986 
5987 	r5l_flush_stripe_to_raid(conf->log);
5988 	if (release_inactive) {
5989 		spin_lock_irq(&conf->device_lock);
5990 		return 0;
5991 	}
5992 
5993 	for (i = 0; i < batch_size; i++)
5994 		handle_stripe(batch[i]);
5995 	r5l_write_stripe_run(conf->log);
5996 
5997 	cond_resched();
5998 
5999 	spin_lock_irq(&conf->device_lock);
6000 	for (i = 0; i < batch_size; i++) {
6001 		hash = batch[i]->hash_lock_index;
6002 		__release_stripe(conf, batch[i], &temp_inactive_list[hash]);
6003 	}
6004 	return batch_size;
6005 }
6006 
6007 static void raid5_do_work(struct work_struct *work)
6008 {
6009 	struct r5worker *worker = container_of(work, struct r5worker, work);
6010 	struct r5worker_group *group = worker->group;
6011 	struct r5conf *conf = group->conf;
6012 	int group_id = group - conf->worker_groups;
6013 	int handled;
6014 	struct blk_plug plug;
6015 
6016 	pr_debug("+++ raid5worker active\n");
6017 
6018 	blk_start_plug(&plug);
6019 	handled = 0;
6020 	spin_lock_irq(&conf->device_lock);
6021 	while (1) {
6022 		int batch_size, released;
6023 
6024 		released = release_stripe_list(conf, worker->temp_inactive_list);
6025 
6026 		batch_size = handle_active_stripes(conf, group_id, worker,
6027 						   worker->temp_inactive_list);
6028 		worker->working = false;
6029 		if (!batch_size && !released)
6030 			break;
6031 		handled += batch_size;
6032 	}
6033 	pr_debug("%d stripes handled\n", handled);
6034 
6035 	spin_unlock_irq(&conf->device_lock);
6036 	blk_finish_plug(&plug);
6037 
6038 	pr_debug("--- raid5worker inactive\n");
6039 }
6040 
6041 /*
6042  * This is our raid5 kernel thread.
6043  *
6044  * We scan the hash table for stripes which can be handled now.
6045  * During the scan, completed stripes are saved for us by the interrupt
6046  * handler, so that they will not have to wait for our next wakeup.
6047  */
6048 static void raid5d(struct md_thread *thread)
6049 {
6050 	struct mddev *mddev = thread->mddev;
6051 	struct r5conf *conf = mddev->private;
6052 	int handled;
6053 	struct blk_plug plug;
6054 
6055 	pr_debug("+++ raid5d active\n");
6056 
6057 	md_check_recovery(mddev);
6058 
6059 	if (!bio_list_empty(&conf->return_bi) &&
6060 	    !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
6061 		struct bio_list tmp = BIO_EMPTY_LIST;
6062 		spin_lock_irq(&conf->device_lock);
6063 		if (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
6064 			bio_list_merge(&tmp, &conf->return_bi);
6065 			bio_list_init(&conf->return_bi);
6066 		}
6067 		spin_unlock_irq(&conf->device_lock);
6068 		return_io(&tmp);
6069 	}
6070 
6071 	blk_start_plug(&plug);
6072 	handled = 0;
6073 	spin_lock_irq(&conf->device_lock);
6074 	while (1) {
6075 		struct bio *bio;
6076 		int batch_size, released;
6077 
6078 		released = release_stripe_list(conf, conf->temp_inactive_list);
6079 		if (released)
6080 			clear_bit(R5_DID_ALLOC, &conf->cache_state);
6081 
6082 		if (
6083 		    !list_empty(&conf->bitmap_list)) {
6084 			/* Now is a good time to flush some bitmap updates */
6085 			conf->seq_flush++;
6086 			spin_unlock_irq(&conf->device_lock);
6087 			bitmap_unplug(mddev->bitmap);
6088 			spin_lock_irq(&conf->device_lock);
6089 			conf->seq_write = conf->seq_flush;
6090 			activate_bit_delay(conf, conf->temp_inactive_list);
6091 		}
6092 		raid5_activate_delayed(conf);
6093 
6094 		while ((bio = remove_bio_from_retry(conf))) {
6095 			int ok;
6096 			spin_unlock_irq(&conf->device_lock);
6097 			ok = retry_aligned_read(conf, bio);
6098 			spin_lock_irq(&conf->device_lock);
6099 			if (!ok)
6100 				break;
6101 			handled++;
6102 		}
6103 
6104 		batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
6105 						   conf->temp_inactive_list);
6106 		if (!batch_size && !released)
6107 			break;
6108 		handled += batch_size;
6109 
6110 		if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
6111 			spin_unlock_irq(&conf->device_lock);
6112 			md_check_recovery(mddev);
6113 			spin_lock_irq(&conf->device_lock);
6114 		}
6115 	}
6116 	pr_debug("%d stripes handled\n", handled);
6117 
6118 	spin_unlock_irq(&conf->device_lock);
6119 	if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
6120 	    mutex_trylock(&conf->cache_size_mutex)) {
6121 		grow_one_stripe(conf, __GFP_NOWARN);
6122 		/* Set flag even if allocation failed.  This helps
6123 		 * slow down allocation requests when mem is short
6124 		 */
6125 		set_bit(R5_DID_ALLOC, &conf->cache_state);
6126 		mutex_unlock(&conf->cache_size_mutex);
6127 	}
6128 
6129 	r5l_flush_stripe_to_raid(conf->log);
6130 
6131 	async_tx_issue_pending_all();
6132 	blk_finish_plug(&plug);
6133 
6134 	pr_debug("--- raid5d inactive\n");
6135 }
6136 
6137 static ssize_t
6138 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
6139 {
6140 	struct r5conf *conf;
6141 	int ret = 0;
6142 	spin_lock(&mddev->lock);
6143 	conf = mddev->private;
6144 	if (conf)
6145 		ret = sprintf(page, "%d\n", conf->min_nr_stripes);
6146 	spin_unlock(&mddev->lock);
6147 	return ret;
6148 }
6149 
6150 int
6151 raid5_set_cache_size(struct mddev *mddev, int size)
6152 {
6153 	struct r5conf *conf = mddev->private;
6154 	int err;
6155 
6156 	if (size <= 16 || size > 32768)
6157 		return -EINVAL;
6158 
6159 	conf->min_nr_stripes = size;
6160 	mutex_lock(&conf->cache_size_mutex);
6161 	while (size < conf->max_nr_stripes &&
6162 	       drop_one_stripe(conf))
6163 		;
6164 	mutex_unlock(&conf->cache_size_mutex);
6165 
6166 
6167 	err = md_allow_write(mddev);
6168 	if (err)
6169 		return err;
6170 
6171 	mutex_lock(&conf->cache_size_mutex);
6172 	while (size > conf->max_nr_stripes)
6173 		if (!grow_one_stripe(conf, GFP_KERNEL))
6174 			break;
6175 	mutex_unlock(&conf->cache_size_mutex);
6176 
6177 	return 0;
6178 }
6179 EXPORT_SYMBOL(raid5_set_cache_size);
6180 
6181 static ssize_t
6182 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6183 {
6184 	struct r5conf *conf;
6185 	unsigned long new;
6186 	int err;
6187 
6188 	if (len >= PAGE_SIZE)
6189 		return -EINVAL;
6190 	if (kstrtoul(page, 10, &new))
6191 		return -EINVAL;
6192 	err = mddev_lock(mddev);
6193 	if (err)
6194 		return err;
6195 	conf = mddev->private;
6196 	if (!conf)
6197 		err = -ENODEV;
6198 	else
6199 		err = raid5_set_cache_size(mddev, new);
6200 	mddev_unlock(mddev);
6201 
6202 	return err ?: len;
6203 }
6204 
6205 static struct md_sysfs_entry
6206 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6207 				raid5_show_stripe_cache_size,
6208 				raid5_store_stripe_cache_size);
6209 
6210 static ssize_t
6211 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6212 {
6213 	struct r5conf *conf = mddev->private;
6214 	if (conf)
6215 		return sprintf(page, "%d\n", conf->rmw_level);
6216 	else
6217 		return 0;
6218 }
6219 
6220 static ssize_t
6221 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6222 {
6223 	struct r5conf *conf = mddev->private;
6224 	unsigned long new;
6225 
6226 	if (!conf)
6227 		return -ENODEV;
6228 
6229 	if (len >= PAGE_SIZE)
6230 		return -EINVAL;
6231 
6232 	if (kstrtoul(page, 10, &new))
6233 		return -EINVAL;
6234 
6235 	if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6236 		return -EINVAL;
6237 
6238 	if (new != PARITY_DISABLE_RMW &&
6239 	    new != PARITY_ENABLE_RMW &&
6240 	    new != PARITY_PREFER_RMW)
6241 		return -EINVAL;
6242 
6243 	conf->rmw_level = new;
6244 	return len;
6245 }
6246 
6247 static struct md_sysfs_entry
6248 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
6249 			 raid5_show_rmw_level,
6250 			 raid5_store_rmw_level);
6251 
6252 
6253 static ssize_t
6254 raid5_show_preread_threshold(struct mddev *mddev, char *page)
6255 {
6256 	struct r5conf *conf;
6257 	int ret = 0;
6258 	spin_lock(&mddev->lock);
6259 	conf = mddev->private;
6260 	if (conf)
6261 		ret = sprintf(page, "%d\n", conf->bypass_threshold);
6262 	spin_unlock(&mddev->lock);
6263 	return ret;
6264 }
6265 
6266 static ssize_t
6267 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
6268 {
6269 	struct r5conf *conf;
6270 	unsigned long new;
6271 	int err;
6272 
6273 	if (len >= PAGE_SIZE)
6274 		return -EINVAL;
6275 	if (kstrtoul(page, 10, &new))
6276 		return -EINVAL;
6277 
6278 	err = mddev_lock(mddev);
6279 	if (err)
6280 		return err;
6281 	conf = mddev->private;
6282 	if (!conf)
6283 		err = -ENODEV;
6284 	else if (new > conf->min_nr_stripes)
6285 		err = -EINVAL;
6286 	else
6287 		conf->bypass_threshold = new;
6288 	mddev_unlock(mddev);
6289 	return err ?: len;
6290 }
6291 
6292 static struct md_sysfs_entry
6293 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6294 					S_IRUGO | S_IWUSR,
6295 					raid5_show_preread_threshold,
6296 					raid5_store_preread_threshold);
6297 
6298 static ssize_t
6299 raid5_show_skip_copy(struct mddev *mddev, char *page)
6300 {
6301 	struct r5conf *conf;
6302 	int ret = 0;
6303 	spin_lock(&mddev->lock);
6304 	conf = mddev->private;
6305 	if (conf)
6306 		ret = sprintf(page, "%d\n", conf->skip_copy);
6307 	spin_unlock(&mddev->lock);
6308 	return ret;
6309 }
6310 
6311 static ssize_t
6312 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6313 {
6314 	struct r5conf *conf;
6315 	unsigned long new;
6316 	int err;
6317 
6318 	if (len >= PAGE_SIZE)
6319 		return -EINVAL;
6320 	if (kstrtoul(page, 10, &new))
6321 		return -EINVAL;
6322 	new = !!new;
6323 
6324 	err = mddev_lock(mddev);
6325 	if (err)
6326 		return err;
6327 	conf = mddev->private;
6328 	if (!conf)
6329 		err = -ENODEV;
6330 	else if (new != conf->skip_copy) {
6331 		mddev_suspend(mddev);
6332 		conf->skip_copy = new;
6333 		if (new)
6334 			mddev->queue->backing_dev_info->capabilities |=
6335 				BDI_CAP_STABLE_WRITES;
6336 		else
6337 			mddev->queue->backing_dev_info->capabilities &=
6338 				~BDI_CAP_STABLE_WRITES;
6339 		mddev_resume(mddev);
6340 	}
6341 	mddev_unlock(mddev);
6342 	return err ?: len;
6343 }
6344 
6345 static struct md_sysfs_entry
6346 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6347 					raid5_show_skip_copy,
6348 					raid5_store_skip_copy);
6349 
6350 static ssize_t
6351 stripe_cache_active_show(struct mddev *mddev, char *page)
6352 {
6353 	struct r5conf *conf = mddev->private;
6354 	if (conf)
6355 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6356 	else
6357 		return 0;
6358 }
6359 
6360 static struct md_sysfs_entry
6361 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6362 
6363 static ssize_t
6364 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6365 {
6366 	struct r5conf *conf;
6367 	int ret = 0;
6368 	spin_lock(&mddev->lock);
6369 	conf = mddev->private;
6370 	if (conf)
6371 		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6372 	spin_unlock(&mddev->lock);
6373 	return ret;
6374 }
6375 
6376 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6377 			       int *group_cnt,
6378 			       int *worker_cnt_per_group,
6379 			       struct r5worker_group **worker_groups);
6380 static ssize_t
6381 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6382 {
6383 	struct r5conf *conf;
6384 	unsigned long new;
6385 	int err;
6386 	struct r5worker_group *new_groups, *old_groups;
6387 	int group_cnt, worker_cnt_per_group;
6388 
6389 	if (len >= PAGE_SIZE)
6390 		return -EINVAL;
6391 	if (kstrtoul(page, 10, &new))
6392 		return -EINVAL;
6393 
6394 	err = mddev_lock(mddev);
6395 	if (err)
6396 		return err;
6397 	conf = mddev->private;
6398 	if (!conf)
6399 		err = -ENODEV;
6400 	else if (new != conf->worker_cnt_per_group) {
6401 		mddev_suspend(mddev);
6402 
6403 		old_groups = conf->worker_groups;
6404 		if (old_groups)
6405 			flush_workqueue(raid5_wq);
6406 
6407 		err = alloc_thread_groups(conf, new,
6408 					  &group_cnt, &worker_cnt_per_group,
6409 					  &new_groups);
6410 		if (!err) {
6411 			spin_lock_irq(&conf->device_lock);
6412 			conf->group_cnt = group_cnt;
6413 			conf->worker_cnt_per_group = worker_cnt_per_group;
6414 			conf->worker_groups = new_groups;
6415 			spin_unlock_irq(&conf->device_lock);
6416 
6417 			if (old_groups)
6418 				kfree(old_groups[0].workers);
6419 			kfree(old_groups);
6420 		}
6421 		mddev_resume(mddev);
6422 	}
6423 	mddev_unlock(mddev);
6424 
6425 	return err ?: len;
6426 }
6427 
6428 static struct md_sysfs_entry
6429 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6430 				raid5_show_group_thread_cnt,
6431 				raid5_store_group_thread_cnt);
6432 
6433 static struct attribute *raid5_attrs[] =  {
6434 	&raid5_stripecache_size.attr,
6435 	&raid5_stripecache_active.attr,
6436 	&raid5_preread_bypass_threshold.attr,
6437 	&raid5_group_thread_cnt.attr,
6438 	&raid5_skip_copy.attr,
6439 	&raid5_rmw_level.attr,
6440 	&r5c_journal_mode.attr,
6441 	NULL,
6442 };
6443 static struct attribute_group raid5_attrs_group = {
6444 	.name = NULL,
6445 	.attrs = raid5_attrs,
6446 };
6447 
6448 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6449 			       int *group_cnt,
6450 			       int *worker_cnt_per_group,
6451 			       struct r5worker_group **worker_groups)
6452 {
6453 	int i, j, k;
6454 	ssize_t size;
6455 	struct r5worker *workers;
6456 
6457 	*worker_cnt_per_group = cnt;
6458 	if (cnt == 0) {
6459 		*group_cnt = 0;
6460 		*worker_groups = NULL;
6461 		return 0;
6462 	}
6463 	*group_cnt = num_possible_nodes();
6464 	size = sizeof(struct r5worker) * cnt;
6465 	workers = kzalloc(size * *group_cnt, GFP_NOIO);
6466 	*worker_groups = kzalloc(sizeof(struct r5worker_group) *
6467 				*group_cnt, GFP_NOIO);
6468 	if (!*worker_groups || !workers) {
6469 		kfree(workers);
6470 		kfree(*worker_groups);
6471 		return -ENOMEM;
6472 	}
6473 
6474 	for (i = 0; i < *group_cnt; i++) {
6475 		struct r5worker_group *group;
6476 
6477 		group = &(*worker_groups)[i];
6478 		INIT_LIST_HEAD(&group->handle_list);
6479 		group->conf = conf;
6480 		group->workers = workers + i * cnt;
6481 
6482 		for (j = 0; j < cnt; j++) {
6483 			struct r5worker *worker = group->workers + j;
6484 			worker->group = group;
6485 			INIT_WORK(&worker->work, raid5_do_work);
6486 
6487 			for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6488 				INIT_LIST_HEAD(worker->temp_inactive_list + k);
6489 		}
6490 	}
6491 
6492 	return 0;
6493 }
6494 
6495 static void free_thread_groups(struct r5conf *conf)
6496 {
6497 	if (conf->worker_groups)
6498 		kfree(conf->worker_groups[0].workers);
6499 	kfree(conf->worker_groups);
6500 	conf->worker_groups = NULL;
6501 }
6502 
6503 static sector_t
6504 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6505 {
6506 	struct r5conf *conf = mddev->private;
6507 
6508 	if (!sectors)
6509 		sectors = mddev->dev_sectors;
6510 	if (!raid_disks)
6511 		/* size is defined by the smallest of previous and new size */
6512 		raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6513 
6514 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
6515 	sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
6516 	return sectors * (raid_disks - conf->max_degraded);
6517 }
6518 
6519 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6520 {
6521 	safe_put_page(percpu->spare_page);
6522 	if (percpu->scribble)
6523 		flex_array_free(percpu->scribble);
6524 	percpu->spare_page = NULL;
6525 	percpu->scribble = NULL;
6526 }
6527 
6528 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6529 {
6530 	if (conf->level == 6 && !percpu->spare_page)
6531 		percpu->spare_page = alloc_page(GFP_KERNEL);
6532 	if (!percpu->scribble)
6533 		percpu->scribble = scribble_alloc(max(conf->raid_disks,
6534 						      conf->previous_raid_disks),
6535 						  max(conf->chunk_sectors,
6536 						      conf->prev_chunk_sectors)
6537 						   / STRIPE_SECTORS,
6538 						  GFP_KERNEL);
6539 
6540 	if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6541 		free_scratch_buffer(conf, percpu);
6542 		return -ENOMEM;
6543 	}
6544 
6545 	return 0;
6546 }
6547 
6548 static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
6549 {
6550 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6551 
6552 	free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6553 	return 0;
6554 }
6555 
6556 static void raid5_free_percpu(struct r5conf *conf)
6557 {
6558 	if (!conf->percpu)
6559 		return;
6560 
6561 	cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6562 	free_percpu(conf->percpu);
6563 }
6564 
6565 static void free_conf(struct r5conf *conf)
6566 {
6567 	int i;
6568 
6569 	if (conf->log)
6570 		r5l_exit_log(conf->log);
6571 	if (conf->shrinker.nr_deferred)
6572 		unregister_shrinker(&conf->shrinker);
6573 
6574 	free_thread_groups(conf);
6575 	shrink_stripes(conf);
6576 	raid5_free_percpu(conf);
6577 	for (i = 0; i < conf->pool_size; i++)
6578 		if (conf->disks[i].extra_page)
6579 			put_page(conf->disks[i].extra_page);
6580 	kfree(conf->disks);
6581 	kfree(conf->stripe_hashtbl);
6582 	kfree(conf);
6583 }
6584 
6585 static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
6586 {
6587 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6588 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6589 
6590 	if (alloc_scratch_buffer(conf, percpu)) {
6591 		pr_warn("%s: failed memory allocation for cpu%u\n",
6592 			__func__, cpu);
6593 		return -ENOMEM;
6594 	}
6595 	return 0;
6596 }
6597 
6598 static int raid5_alloc_percpu(struct r5conf *conf)
6599 {
6600 	int err = 0;
6601 
6602 	conf->percpu = alloc_percpu(struct raid5_percpu);
6603 	if (!conf->percpu)
6604 		return -ENOMEM;
6605 
6606 	err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6607 	if (!err) {
6608 		conf->scribble_disks = max(conf->raid_disks,
6609 			conf->previous_raid_disks);
6610 		conf->scribble_sectors = max(conf->chunk_sectors,
6611 			conf->prev_chunk_sectors);
6612 	}
6613 	return err;
6614 }
6615 
6616 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6617 				      struct shrink_control *sc)
6618 {
6619 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6620 	unsigned long ret = SHRINK_STOP;
6621 
6622 	if (mutex_trylock(&conf->cache_size_mutex)) {
6623 		ret= 0;
6624 		while (ret < sc->nr_to_scan &&
6625 		       conf->max_nr_stripes > conf->min_nr_stripes) {
6626 			if (drop_one_stripe(conf) == 0) {
6627 				ret = SHRINK_STOP;
6628 				break;
6629 			}
6630 			ret++;
6631 		}
6632 		mutex_unlock(&conf->cache_size_mutex);
6633 	}
6634 	return ret;
6635 }
6636 
6637 static unsigned long raid5_cache_count(struct shrinker *shrink,
6638 				       struct shrink_control *sc)
6639 {
6640 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6641 
6642 	if (conf->max_nr_stripes < conf->min_nr_stripes)
6643 		/* unlikely, but not impossible */
6644 		return 0;
6645 	return conf->max_nr_stripes - conf->min_nr_stripes;
6646 }
6647 
6648 static struct r5conf *setup_conf(struct mddev *mddev)
6649 {
6650 	struct r5conf *conf;
6651 	int raid_disk, memory, max_disks;
6652 	struct md_rdev *rdev;
6653 	struct disk_info *disk;
6654 	char pers_name[6];
6655 	int i;
6656 	int group_cnt, worker_cnt_per_group;
6657 	struct r5worker_group *new_group;
6658 
6659 	if (mddev->new_level != 5
6660 	    && mddev->new_level != 4
6661 	    && mddev->new_level != 6) {
6662 		pr_warn("md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6663 			mdname(mddev), mddev->new_level);
6664 		return ERR_PTR(-EIO);
6665 	}
6666 	if ((mddev->new_level == 5
6667 	     && !algorithm_valid_raid5(mddev->new_layout)) ||
6668 	    (mddev->new_level == 6
6669 	     && !algorithm_valid_raid6(mddev->new_layout))) {
6670 		pr_warn("md/raid:%s: layout %d not supported\n",
6671 			mdname(mddev), mddev->new_layout);
6672 		return ERR_PTR(-EIO);
6673 	}
6674 	if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6675 		pr_warn("md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6676 			mdname(mddev), mddev->raid_disks);
6677 		return ERR_PTR(-EINVAL);
6678 	}
6679 
6680 	if (!mddev->new_chunk_sectors ||
6681 	    (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6682 	    !is_power_of_2(mddev->new_chunk_sectors)) {
6683 		pr_warn("md/raid:%s: invalid chunk size %d\n",
6684 			mdname(mddev), mddev->new_chunk_sectors << 9);
6685 		return ERR_PTR(-EINVAL);
6686 	}
6687 
6688 	conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6689 	if (conf == NULL)
6690 		goto abort;
6691 	/* Don't enable multi-threading by default*/
6692 	if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6693 				 &new_group)) {
6694 		conf->group_cnt = group_cnt;
6695 		conf->worker_cnt_per_group = worker_cnt_per_group;
6696 		conf->worker_groups = new_group;
6697 	} else
6698 		goto abort;
6699 	spin_lock_init(&conf->device_lock);
6700 	seqcount_init(&conf->gen_lock);
6701 	mutex_init(&conf->cache_size_mutex);
6702 	init_waitqueue_head(&conf->wait_for_quiescent);
6703 	init_waitqueue_head(&conf->wait_for_stripe);
6704 	init_waitqueue_head(&conf->wait_for_overlap);
6705 	INIT_LIST_HEAD(&conf->handle_list);
6706 	INIT_LIST_HEAD(&conf->hold_list);
6707 	INIT_LIST_HEAD(&conf->delayed_list);
6708 	INIT_LIST_HEAD(&conf->bitmap_list);
6709 	bio_list_init(&conf->return_bi);
6710 	init_llist_head(&conf->released_stripes);
6711 	atomic_set(&conf->active_stripes, 0);
6712 	atomic_set(&conf->preread_active_stripes, 0);
6713 	atomic_set(&conf->active_aligned_reads, 0);
6714 	conf->bypass_threshold = BYPASS_THRESHOLD;
6715 	conf->recovery_disabled = mddev->recovery_disabled - 1;
6716 
6717 	conf->raid_disks = mddev->raid_disks;
6718 	if (mddev->reshape_position == MaxSector)
6719 		conf->previous_raid_disks = mddev->raid_disks;
6720 	else
6721 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6722 	max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6723 
6724 	conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6725 			      GFP_KERNEL);
6726 
6727 	if (!conf->disks)
6728 		goto abort;
6729 
6730 	for (i = 0; i < max_disks; i++) {
6731 		conf->disks[i].extra_page = alloc_page(GFP_KERNEL);
6732 		if (!conf->disks[i].extra_page)
6733 			goto abort;
6734 	}
6735 
6736 	conf->mddev = mddev;
6737 
6738 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6739 		goto abort;
6740 
6741 	/* We init hash_locks[0] separately to that it can be used
6742 	 * as the reference lock in the spin_lock_nest_lock() call
6743 	 * in lock_all_device_hash_locks_irq in order to convince
6744 	 * lockdep that we know what we are doing.
6745 	 */
6746 	spin_lock_init(conf->hash_locks);
6747 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6748 		spin_lock_init(conf->hash_locks + i);
6749 
6750 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6751 		INIT_LIST_HEAD(conf->inactive_list + i);
6752 
6753 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6754 		INIT_LIST_HEAD(conf->temp_inactive_list + i);
6755 
6756 	atomic_set(&conf->r5c_cached_full_stripes, 0);
6757 	INIT_LIST_HEAD(&conf->r5c_full_stripe_list);
6758 	atomic_set(&conf->r5c_cached_partial_stripes, 0);
6759 	INIT_LIST_HEAD(&conf->r5c_partial_stripe_list);
6760 
6761 	conf->level = mddev->new_level;
6762 	conf->chunk_sectors = mddev->new_chunk_sectors;
6763 	if (raid5_alloc_percpu(conf) != 0)
6764 		goto abort;
6765 
6766 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6767 
6768 	rdev_for_each(rdev, mddev) {
6769 		raid_disk = rdev->raid_disk;
6770 		if (raid_disk >= max_disks
6771 		    || raid_disk < 0 || test_bit(Journal, &rdev->flags))
6772 			continue;
6773 		disk = conf->disks + raid_disk;
6774 
6775 		if (test_bit(Replacement, &rdev->flags)) {
6776 			if (disk->replacement)
6777 				goto abort;
6778 			disk->replacement = rdev;
6779 		} else {
6780 			if (disk->rdev)
6781 				goto abort;
6782 			disk->rdev = rdev;
6783 		}
6784 
6785 		if (test_bit(In_sync, &rdev->flags)) {
6786 			char b[BDEVNAME_SIZE];
6787 			pr_info("md/raid:%s: device %s operational as raid disk %d\n",
6788 				mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
6789 		} else if (rdev->saved_raid_disk != raid_disk)
6790 			/* Cannot rely on bitmap to complete recovery */
6791 			conf->fullsync = 1;
6792 	}
6793 
6794 	conf->level = mddev->new_level;
6795 	if (conf->level == 6) {
6796 		conf->max_degraded = 2;
6797 		if (raid6_call.xor_syndrome)
6798 			conf->rmw_level = PARITY_ENABLE_RMW;
6799 		else
6800 			conf->rmw_level = PARITY_DISABLE_RMW;
6801 	} else {
6802 		conf->max_degraded = 1;
6803 		conf->rmw_level = PARITY_ENABLE_RMW;
6804 	}
6805 	conf->algorithm = mddev->new_layout;
6806 	conf->reshape_progress = mddev->reshape_position;
6807 	if (conf->reshape_progress != MaxSector) {
6808 		conf->prev_chunk_sectors = mddev->chunk_sectors;
6809 		conf->prev_algo = mddev->layout;
6810 	} else {
6811 		conf->prev_chunk_sectors = conf->chunk_sectors;
6812 		conf->prev_algo = conf->algorithm;
6813 	}
6814 
6815 	conf->min_nr_stripes = NR_STRIPES;
6816 	if (mddev->reshape_position != MaxSector) {
6817 		int stripes = max_t(int,
6818 			((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4,
6819 			((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4);
6820 		conf->min_nr_stripes = max(NR_STRIPES, stripes);
6821 		if (conf->min_nr_stripes != NR_STRIPES)
6822 			pr_info("md/raid:%s: force stripe size %d for reshape\n",
6823 				mdname(mddev), conf->min_nr_stripes);
6824 	}
6825 	memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
6826 		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
6827 	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
6828 	if (grow_stripes(conf, conf->min_nr_stripes)) {
6829 		pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
6830 			mdname(mddev), memory);
6831 		goto abort;
6832 	} else
6833 		pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
6834 	/*
6835 	 * Losing a stripe head costs more than the time to refill it,
6836 	 * it reduces the queue depth and so can hurt throughput.
6837 	 * So set it rather large, scaled by number of devices.
6838 	 */
6839 	conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
6840 	conf->shrinker.scan_objects = raid5_cache_scan;
6841 	conf->shrinker.count_objects = raid5_cache_count;
6842 	conf->shrinker.batch = 128;
6843 	conf->shrinker.flags = 0;
6844 	if (register_shrinker(&conf->shrinker)) {
6845 		pr_warn("md/raid:%s: couldn't register shrinker.\n",
6846 			mdname(mddev));
6847 		goto abort;
6848 	}
6849 
6850 	sprintf(pers_name, "raid%d", mddev->new_level);
6851 	conf->thread = md_register_thread(raid5d, mddev, pers_name);
6852 	if (!conf->thread) {
6853 		pr_warn("md/raid:%s: couldn't allocate thread.\n",
6854 			mdname(mddev));
6855 		goto abort;
6856 	}
6857 
6858 	return conf;
6859 
6860  abort:
6861 	if (conf) {
6862 		free_conf(conf);
6863 		return ERR_PTR(-EIO);
6864 	} else
6865 		return ERR_PTR(-ENOMEM);
6866 }
6867 
6868 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
6869 {
6870 	switch (algo) {
6871 	case ALGORITHM_PARITY_0:
6872 		if (raid_disk < max_degraded)
6873 			return 1;
6874 		break;
6875 	case ALGORITHM_PARITY_N:
6876 		if (raid_disk >= raid_disks - max_degraded)
6877 			return 1;
6878 		break;
6879 	case ALGORITHM_PARITY_0_6:
6880 		if (raid_disk == 0 ||
6881 		    raid_disk == raid_disks - 1)
6882 			return 1;
6883 		break;
6884 	case ALGORITHM_LEFT_ASYMMETRIC_6:
6885 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
6886 	case ALGORITHM_LEFT_SYMMETRIC_6:
6887 	case ALGORITHM_RIGHT_SYMMETRIC_6:
6888 		if (raid_disk == raid_disks - 1)
6889 			return 1;
6890 	}
6891 	return 0;
6892 }
6893 
6894 static int raid5_run(struct mddev *mddev)
6895 {
6896 	struct r5conf *conf;
6897 	int working_disks = 0;
6898 	int dirty_parity_disks = 0;
6899 	struct md_rdev *rdev;
6900 	struct md_rdev *journal_dev = NULL;
6901 	sector_t reshape_offset = 0;
6902 	int i;
6903 	long long min_offset_diff = 0;
6904 	int first = 1;
6905 
6906 	if (mddev->recovery_cp != MaxSector)
6907 		pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
6908 			  mdname(mddev));
6909 
6910 	rdev_for_each(rdev, mddev) {
6911 		long long diff;
6912 
6913 		if (test_bit(Journal, &rdev->flags)) {
6914 			journal_dev = rdev;
6915 			continue;
6916 		}
6917 		if (rdev->raid_disk < 0)
6918 			continue;
6919 		diff = (rdev->new_data_offset - rdev->data_offset);
6920 		if (first) {
6921 			min_offset_diff = diff;
6922 			first = 0;
6923 		} else if (mddev->reshape_backwards &&
6924 			 diff < min_offset_diff)
6925 			min_offset_diff = diff;
6926 		else if (!mddev->reshape_backwards &&
6927 			 diff > min_offset_diff)
6928 			min_offset_diff = diff;
6929 	}
6930 
6931 	if (mddev->reshape_position != MaxSector) {
6932 		/* Check that we can continue the reshape.
6933 		 * Difficulties arise if the stripe we would write to
6934 		 * next is at or after the stripe we would read from next.
6935 		 * For a reshape that changes the number of devices, this
6936 		 * is only possible for a very short time, and mdadm makes
6937 		 * sure that time appears to have past before assembling
6938 		 * the array.  So we fail if that time hasn't passed.
6939 		 * For a reshape that keeps the number of devices the same
6940 		 * mdadm must be monitoring the reshape can keeping the
6941 		 * critical areas read-only and backed up.  It will start
6942 		 * the array in read-only mode, so we check for that.
6943 		 */
6944 		sector_t here_new, here_old;
6945 		int old_disks;
6946 		int max_degraded = (mddev->level == 6 ? 2 : 1);
6947 		int chunk_sectors;
6948 		int new_data_disks;
6949 
6950 		if (journal_dev) {
6951 			pr_warn("md/raid:%s: don't support reshape with journal - aborting.\n",
6952 				mdname(mddev));
6953 			return -EINVAL;
6954 		}
6955 
6956 		if (mddev->new_level != mddev->level) {
6957 			pr_warn("md/raid:%s: unsupported reshape required - aborting.\n",
6958 				mdname(mddev));
6959 			return -EINVAL;
6960 		}
6961 		old_disks = mddev->raid_disks - mddev->delta_disks;
6962 		/* reshape_position must be on a new-stripe boundary, and one
6963 		 * further up in new geometry must map after here in old
6964 		 * geometry.
6965 		 * If the chunk sizes are different, then as we perform reshape
6966 		 * in units of the largest of the two, reshape_position needs
6967 		 * be a multiple of the largest chunk size times new data disks.
6968 		 */
6969 		here_new = mddev->reshape_position;
6970 		chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
6971 		new_data_disks = mddev->raid_disks - max_degraded;
6972 		if (sector_div(here_new, chunk_sectors * new_data_disks)) {
6973 			pr_warn("md/raid:%s: reshape_position not on a stripe boundary\n",
6974 				mdname(mddev));
6975 			return -EINVAL;
6976 		}
6977 		reshape_offset = here_new * chunk_sectors;
6978 		/* here_new is the stripe we will write to */
6979 		here_old = mddev->reshape_position;
6980 		sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
6981 		/* here_old is the first stripe that we might need to read
6982 		 * from */
6983 		if (mddev->delta_disks == 0) {
6984 			/* We cannot be sure it is safe to start an in-place
6985 			 * reshape.  It is only safe if user-space is monitoring
6986 			 * and taking constant backups.
6987 			 * mdadm always starts a situation like this in
6988 			 * readonly mode so it can take control before
6989 			 * allowing any writes.  So just check for that.
6990 			 */
6991 			if (abs(min_offset_diff) >= mddev->chunk_sectors &&
6992 			    abs(min_offset_diff) >= mddev->new_chunk_sectors)
6993 				/* not really in-place - so OK */;
6994 			else if (mddev->ro == 0) {
6995 				pr_warn("md/raid:%s: in-place reshape must be started in read-only mode - aborting\n",
6996 					mdname(mddev));
6997 				return -EINVAL;
6998 			}
6999 		} else if (mddev->reshape_backwards
7000 		    ? (here_new * chunk_sectors + min_offset_diff <=
7001 		       here_old * chunk_sectors)
7002 		    : (here_new * chunk_sectors >=
7003 		       here_old * chunk_sectors + (-min_offset_diff))) {
7004 			/* Reading from the same stripe as writing to - bad */
7005 			pr_warn("md/raid:%s: reshape_position too early for auto-recovery - aborting.\n",
7006 				mdname(mddev));
7007 			return -EINVAL;
7008 		}
7009 		pr_debug("md/raid:%s: reshape will continue\n", mdname(mddev));
7010 		/* OK, we should be able to continue; */
7011 	} else {
7012 		BUG_ON(mddev->level != mddev->new_level);
7013 		BUG_ON(mddev->layout != mddev->new_layout);
7014 		BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
7015 		BUG_ON(mddev->delta_disks != 0);
7016 	}
7017 
7018 	if (mddev->private == NULL)
7019 		conf = setup_conf(mddev);
7020 	else
7021 		conf = mddev->private;
7022 
7023 	if (IS_ERR(conf))
7024 		return PTR_ERR(conf);
7025 
7026 	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
7027 		if (!journal_dev) {
7028 			pr_warn("md/raid:%s: journal disk is missing, force array readonly\n",
7029 				mdname(mddev));
7030 			mddev->ro = 1;
7031 			set_disk_ro(mddev->gendisk, 1);
7032 		} else if (mddev->recovery_cp == MaxSector)
7033 			set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
7034 	}
7035 
7036 	conf->min_offset_diff = min_offset_diff;
7037 	mddev->thread = conf->thread;
7038 	conf->thread = NULL;
7039 	mddev->private = conf;
7040 
7041 	for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
7042 	     i++) {
7043 		rdev = conf->disks[i].rdev;
7044 		if (!rdev && conf->disks[i].replacement) {
7045 			/* The replacement is all we have yet */
7046 			rdev = conf->disks[i].replacement;
7047 			conf->disks[i].replacement = NULL;
7048 			clear_bit(Replacement, &rdev->flags);
7049 			conf->disks[i].rdev = rdev;
7050 		}
7051 		if (!rdev)
7052 			continue;
7053 		if (conf->disks[i].replacement &&
7054 		    conf->reshape_progress != MaxSector) {
7055 			/* replacements and reshape simply do not mix. */
7056 			pr_warn("md: cannot handle concurrent replacement and reshape.\n");
7057 			goto abort;
7058 		}
7059 		if (test_bit(In_sync, &rdev->flags)) {
7060 			working_disks++;
7061 			continue;
7062 		}
7063 		/* This disc is not fully in-sync.  However if it
7064 		 * just stored parity (beyond the recovery_offset),
7065 		 * when we don't need to be concerned about the
7066 		 * array being dirty.
7067 		 * When reshape goes 'backwards', we never have
7068 		 * partially completed devices, so we only need
7069 		 * to worry about reshape going forwards.
7070 		 */
7071 		/* Hack because v0.91 doesn't store recovery_offset properly. */
7072 		if (mddev->major_version == 0 &&
7073 		    mddev->minor_version > 90)
7074 			rdev->recovery_offset = reshape_offset;
7075 
7076 		if (rdev->recovery_offset < reshape_offset) {
7077 			/* We need to check old and new layout */
7078 			if (!only_parity(rdev->raid_disk,
7079 					 conf->algorithm,
7080 					 conf->raid_disks,
7081 					 conf->max_degraded))
7082 				continue;
7083 		}
7084 		if (!only_parity(rdev->raid_disk,
7085 				 conf->prev_algo,
7086 				 conf->previous_raid_disks,
7087 				 conf->max_degraded))
7088 			continue;
7089 		dirty_parity_disks++;
7090 	}
7091 
7092 	/*
7093 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
7094 	 */
7095 	mddev->degraded = raid5_calc_degraded(conf);
7096 
7097 	if (has_failed(conf)) {
7098 		pr_crit("md/raid:%s: not enough operational devices (%d/%d failed)\n",
7099 			mdname(mddev), mddev->degraded, conf->raid_disks);
7100 		goto abort;
7101 	}
7102 
7103 	/* device size must be a multiple of chunk size */
7104 	mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
7105 	mddev->resync_max_sectors = mddev->dev_sectors;
7106 
7107 	if (mddev->degraded > dirty_parity_disks &&
7108 	    mddev->recovery_cp != MaxSector) {
7109 		if (mddev->ok_start_degraded)
7110 			pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
7111 				mdname(mddev));
7112 		else {
7113 			pr_crit("md/raid:%s: cannot start dirty degraded array.\n",
7114 				mdname(mddev));
7115 			goto abort;
7116 		}
7117 	}
7118 
7119 	pr_info("md/raid:%s: raid level %d active with %d out of %d devices, algorithm %d\n",
7120 		mdname(mddev), conf->level,
7121 		mddev->raid_disks-mddev->degraded, mddev->raid_disks,
7122 		mddev->new_layout);
7123 
7124 	print_raid5_conf(conf);
7125 
7126 	if (conf->reshape_progress != MaxSector) {
7127 		conf->reshape_safe = conf->reshape_progress;
7128 		atomic_set(&conf->reshape_stripes, 0);
7129 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7130 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7131 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7132 		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7133 		mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7134 							"reshape");
7135 	}
7136 
7137 	/* Ok, everything is just fine now */
7138 	if (mddev->to_remove == &raid5_attrs_group)
7139 		mddev->to_remove = NULL;
7140 	else if (mddev->kobj.sd &&
7141 	    sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
7142 		pr_warn("raid5: failed to create sysfs attributes for %s\n",
7143 			mdname(mddev));
7144 	md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7145 
7146 	if (mddev->queue) {
7147 		int chunk_size;
7148 		bool discard_supported = true;
7149 		/* read-ahead size must cover two whole stripes, which
7150 		 * is 2 * (datadisks) * chunksize where 'n' is the
7151 		 * number of raid devices
7152 		 */
7153 		int data_disks = conf->previous_raid_disks - conf->max_degraded;
7154 		int stripe = data_disks *
7155 			((mddev->chunk_sectors << 9) / PAGE_SIZE);
7156 		if (mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7157 			mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7158 
7159 		chunk_size = mddev->chunk_sectors << 9;
7160 		blk_queue_io_min(mddev->queue, chunk_size);
7161 		blk_queue_io_opt(mddev->queue, chunk_size *
7162 				 (conf->raid_disks - conf->max_degraded));
7163 		mddev->queue->limits.raid_partial_stripes_expensive = 1;
7164 		/*
7165 		 * We can only discard a whole stripe. It doesn't make sense to
7166 		 * discard data disk but write parity disk
7167 		 */
7168 		stripe = stripe * PAGE_SIZE;
7169 		/* Round up to power of 2, as discard handling
7170 		 * currently assumes that */
7171 		while ((stripe-1) & stripe)
7172 			stripe = (stripe | (stripe-1)) + 1;
7173 		mddev->queue->limits.discard_alignment = stripe;
7174 		mddev->queue->limits.discard_granularity = stripe;
7175 
7176 		/*
7177 		 * We use 16-bit counter of active stripes in bi_phys_segments
7178 		 * (minus one for over-loaded initialization)
7179 		 */
7180 		blk_queue_max_hw_sectors(mddev->queue, 0xfffe * STRIPE_SECTORS);
7181 		blk_queue_max_discard_sectors(mddev->queue,
7182 					      0xfffe * STRIPE_SECTORS);
7183 
7184 		/*
7185 		 * unaligned part of discard request will be ignored, so can't
7186 		 * guarantee discard_zeroes_data
7187 		 */
7188 		mddev->queue->limits.discard_zeroes_data = 0;
7189 
7190 		blk_queue_max_write_same_sectors(mddev->queue, 0);
7191 
7192 		rdev_for_each(rdev, mddev) {
7193 			disk_stack_limits(mddev->gendisk, rdev->bdev,
7194 					  rdev->data_offset << 9);
7195 			disk_stack_limits(mddev->gendisk, rdev->bdev,
7196 					  rdev->new_data_offset << 9);
7197 			/*
7198 			 * discard_zeroes_data is required, otherwise data
7199 			 * could be lost. Consider a scenario: discard a stripe
7200 			 * (the stripe could be inconsistent if
7201 			 * discard_zeroes_data is 0); write one disk of the
7202 			 * stripe (the stripe could be inconsistent again
7203 			 * depending on which disks are used to calculate
7204 			 * parity); the disk is broken; The stripe data of this
7205 			 * disk is lost.
7206 			 */
7207 			if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
7208 			    !bdev_get_queue(rdev->bdev)->
7209 						limits.discard_zeroes_data)
7210 				discard_supported = false;
7211 			/* Unfortunately, discard_zeroes_data is not currently
7212 			 * a guarantee - just a hint.  So we only allow DISCARD
7213 			 * if the sysadmin has confirmed that only safe devices
7214 			 * are in use by setting a module parameter.
7215 			 */
7216 			if (!devices_handle_discard_safely) {
7217 				if (discard_supported) {
7218 					pr_info("md/raid456: discard support disabled due to uncertainty.\n");
7219 					pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
7220 				}
7221 				discard_supported = false;
7222 			}
7223 		}
7224 
7225 		if (discard_supported &&
7226 		    mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
7227 		    mddev->queue->limits.discard_granularity >= stripe)
7228 			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
7229 						mddev->queue);
7230 		else
7231 			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
7232 						mddev->queue);
7233 
7234 		blk_queue_max_hw_sectors(mddev->queue, UINT_MAX);
7235 	}
7236 
7237 	if (journal_dev) {
7238 		char b[BDEVNAME_SIZE];
7239 
7240 		pr_debug("md/raid:%s: using device %s as journal\n",
7241 			 mdname(mddev), bdevname(journal_dev->bdev, b));
7242 		if (r5l_init_log(conf, journal_dev))
7243 			goto abort;
7244 	}
7245 
7246 	return 0;
7247 abort:
7248 	md_unregister_thread(&mddev->thread);
7249 	print_raid5_conf(conf);
7250 	free_conf(conf);
7251 	mddev->private = NULL;
7252 	pr_warn("md/raid:%s: failed to run raid set.\n", mdname(mddev));
7253 	return -EIO;
7254 }
7255 
7256 static void raid5_free(struct mddev *mddev, void *priv)
7257 {
7258 	struct r5conf *conf = priv;
7259 
7260 	free_conf(conf);
7261 	mddev->to_remove = &raid5_attrs_group;
7262 }
7263 
7264 static void raid5_status(struct seq_file *seq, struct mddev *mddev)
7265 {
7266 	struct r5conf *conf = mddev->private;
7267 	int i;
7268 
7269 	seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
7270 		conf->chunk_sectors / 2, mddev->layout);
7271 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
7272 	rcu_read_lock();
7273 	for (i = 0; i < conf->raid_disks; i++) {
7274 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
7275 		seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
7276 	}
7277 	rcu_read_unlock();
7278 	seq_printf (seq, "]");
7279 }
7280 
7281 static void print_raid5_conf (struct r5conf *conf)
7282 {
7283 	int i;
7284 	struct disk_info *tmp;
7285 
7286 	pr_debug("RAID conf printout:\n");
7287 	if (!conf) {
7288 		pr_debug("(conf==NULL)\n");
7289 		return;
7290 	}
7291 	pr_debug(" --- level:%d rd:%d wd:%d\n", conf->level,
7292 	       conf->raid_disks,
7293 	       conf->raid_disks - conf->mddev->degraded);
7294 
7295 	for (i = 0; i < conf->raid_disks; i++) {
7296 		char b[BDEVNAME_SIZE];
7297 		tmp = conf->disks + i;
7298 		if (tmp->rdev)
7299 			pr_debug(" disk %d, o:%d, dev:%s\n",
7300 			       i, !test_bit(Faulty, &tmp->rdev->flags),
7301 			       bdevname(tmp->rdev->bdev, b));
7302 	}
7303 }
7304 
7305 static int raid5_spare_active(struct mddev *mddev)
7306 {
7307 	int i;
7308 	struct r5conf *conf = mddev->private;
7309 	struct disk_info *tmp;
7310 	int count = 0;
7311 	unsigned long flags;
7312 
7313 	for (i = 0; i < conf->raid_disks; i++) {
7314 		tmp = conf->disks + i;
7315 		if (tmp->replacement
7316 		    && tmp->replacement->recovery_offset == MaxSector
7317 		    && !test_bit(Faulty, &tmp->replacement->flags)
7318 		    && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7319 			/* Replacement has just become active. */
7320 			if (!tmp->rdev
7321 			    || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7322 				count++;
7323 			if (tmp->rdev) {
7324 				/* Replaced device not technically faulty,
7325 				 * but we need to be sure it gets removed
7326 				 * and never re-added.
7327 				 */
7328 				set_bit(Faulty, &tmp->rdev->flags);
7329 				sysfs_notify_dirent_safe(
7330 					tmp->rdev->sysfs_state);
7331 			}
7332 			sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7333 		} else if (tmp->rdev
7334 		    && tmp->rdev->recovery_offset == MaxSector
7335 		    && !test_bit(Faulty, &tmp->rdev->flags)
7336 		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7337 			count++;
7338 			sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7339 		}
7340 	}
7341 	spin_lock_irqsave(&conf->device_lock, flags);
7342 	mddev->degraded = raid5_calc_degraded(conf);
7343 	spin_unlock_irqrestore(&conf->device_lock, flags);
7344 	print_raid5_conf(conf);
7345 	return count;
7346 }
7347 
7348 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7349 {
7350 	struct r5conf *conf = mddev->private;
7351 	int err = 0;
7352 	int number = rdev->raid_disk;
7353 	struct md_rdev **rdevp;
7354 	struct disk_info *p = conf->disks + number;
7355 
7356 	print_raid5_conf(conf);
7357 	if (test_bit(Journal, &rdev->flags) && conf->log) {
7358 		struct r5l_log *log;
7359 		/*
7360 		 * we can't wait pending write here, as this is called in
7361 		 * raid5d, wait will deadlock.
7362 		 */
7363 		if (atomic_read(&mddev->writes_pending))
7364 			return -EBUSY;
7365 		log = conf->log;
7366 		conf->log = NULL;
7367 		synchronize_rcu();
7368 		r5l_exit_log(log);
7369 		return 0;
7370 	}
7371 	if (rdev == p->rdev)
7372 		rdevp = &p->rdev;
7373 	else if (rdev == p->replacement)
7374 		rdevp = &p->replacement;
7375 	else
7376 		return 0;
7377 
7378 	if (number >= conf->raid_disks &&
7379 	    conf->reshape_progress == MaxSector)
7380 		clear_bit(In_sync, &rdev->flags);
7381 
7382 	if (test_bit(In_sync, &rdev->flags) ||
7383 	    atomic_read(&rdev->nr_pending)) {
7384 		err = -EBUSY;
7385 		goto abort;
7386 	}
7387 	/* Only remove non-faulty devices if recovery
7388 	 * isn't possible.
7389 	 */
7390 	if (!test_bit(Faulty, &rdev->flags) &&
7391 	    mddev->recovery_disabled != conf->recovery_disabled &&
7392 	    !has_failed(conf) &&
7393 	    (!p->replacement || p->replacement == rdev) &&
7394 	    number < conf->raid_disks) {
7395 		err = -EBUSY;
7396 		goto abort;
7397 	}
7398 	*rdevp = NULL;
7399 	if (!test_bit(RemoveSynchronized, &rdev->flags)) {
7400 		synchronize_rcu();
7401 		if (atomic_read(&rdev->nr_pending)) {
7402 			/* lost the race, try later */
7403 			err = -EBUSY;
7404 			*rdevp = rdev;
7405 		}
7406 	}
7407 	if (p->replacement) {
7408 		/* We must have just cleared 'rdev' */
7409 		p->rdev = p->replacement;
7410 		clear_bit(Replacement, &p->replacement->flags);
7411 		smp_mb(); /* Make sure other CPUs may see both as identical
7412 			   * but will never see neither - if they are careful
7413 			   */
7414 		p->replacement = NULL;
7415 		clear_bit(WantReplacement, &rdev->flags);
7416 	} else
7417 		/* We might have just removed the Replacement as faulty-
7418 		 * clear the bit just in case
7419 		 */
7420 		clear_bit(WantReplacement, &rdev->flags);
7421 abort:
7422 
7423 	print_raid5_conf(conf);
7424 	return err;
7425 }
7426 
7427 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7428 {
7429 	struct r5conf *conf = mddev->private;
7430 	int err = -EEXIST;
7431 	int disk;
7432 	struct disk_info *p;
7433 	int first = 0;
7434 	int last = conf->raid_disks - 1;
7435 
7436 	if (test_bit(Journal, &rdev->flags)) {
7437 		char b[BDEVNAME_SIZE];
7438 		if (conf->log)
7439 			return -EBUSY;
7440 
7441 		rdev->raid_disk = 0;
7442 		/*
7443 		 * The array is in readonly mode if journal is missing, so no
7444 		 * write requests running. We should be safe
7445 		 */
7446 		r5l_init_log(conf, rdev);
7447 		pr_debug("md/raid:%s: using device %s as journal\n",
7448 			 mdname(mddev), bdevname(rdev->bdev, b));
7449 		return 0;
7450 	}
7451 	if (mddev->recovery_disabled == conf->recovery_disabled)
7452 		return -EBUSY;
7453 
7454 	if (rdev->saved_raid_disk < 0 && has_failed(conf))
7455 		/* no point adding a device */
7456 		return -EINVAL;
7457 
7458 	if (rdev->raid_disk >= 0)
7459 		first = last = rdev->raid_disk;
7460 
7461 	/*
7462 	 * find the disk ... but prefer rdev->saved_raid_disk
7463 	 * if possible.
7464 	 */
7465 	if (rdev->saved_raid_disk >= 0 &&
7466 	    rdev->saved_raid_disk >= first &&
7467 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
7468 		first = rdev->saved_raid_disk;
7469 
7470 	for (disk = first; disk <= last; disk++) {
7471 		p = conf->disks + disk;
7472 		if (p->rdev == NULL) {
7473 			clear_bit(In_sync, &rdev->flags);
7474 			rdev->raid_disk = disk;
7475 			err = 0;
7476 			if (rdev->saved_raid_disk != disk)
7477 				conf->fullsync = 1;
7478 			rcu_assign_pointer(p->rdev, rdev);
7479 			goto out;
7480 		}
7481 	}
7482 	for (disk = first; disk <= last; disk++) {
7483 		p = conf->disks + disk;
7484 		if (test_bit(WantReplacement, &p->rdev->flags) &&
7485 		    p->replacement == NULL) {
7486 			clear_bit(In_sync, &rdev->flags);
7487 			set_bit(Replacement, &rdev->flags);
7488 			rdev->raid_disk = disk;
7489 			err = 0;
7490 			conf->fullsync = 1;
7491 			rcu_assign_pointer(p->replacement, rdev);
7492 			break;
7493 		}
7494 	}
7495 out:
7496 	print_raid5_conf(conf);
7497 	return err;
7498 }
7499 
7500 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7501 {
7502 	/* no resync is happening, and there is enough space
7503 	 * on all devices, so we can resize.
7504 	 * We need to make sure resync covers any new space.
7505 	 * If the array is shrinking we should possibly wait until
7506 	 * any io in the removed space completes, but it hardly seems
7507 	 * worth it.
7508 	 */
7509 	sector_t newsize;
7510 	struct r5conf *conf = mddev->private;
7511 
7512 	if (conf->log)
7513 		return -EINVAL;
7514 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
7515 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7516 	if (mddev->external_size &&
7517 	    mddev->array_sectors > newsize)
7518 		return -EINVAL;
7519 	if (mddev->bitmap) {
7520 		int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7521 		if (ret)
7522 			return ret;
7523 	}
7524 	md_set_array_sectors(mddev, newsize);
7525 	set_capacity(mddev->gendisk, mddev->array_sectors);
7526 	revalidate_disk(mddev->gendisk);
7527 	if (sectors > mddev->dev_sectors &&
7528 	    mddev->recovery_cp > mddev->dev_sectors) {
7529 		mddev->recovery_cp = mddev->dev_sectors;
7530 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7531 	}
7532 	mddev->dev_sectors = sectors;
7533 	mddev->resync_max_sectors = sectors;
7534 	return 0;
7535 }
7536 
7537 static int check_stripe_cache(struct mddev *mddev)
7538 {
7539 	/* Can only proceed if there are plenty of stripe_heads.
7540 	 * We need a minimum of one full stripe,, and for sensible progress
7541 	 * it is best to have about 4 times that.
7542 	 * If we require 4 times, then the default 256 4K stripe_heads will
7543 	 * allow for chunk sizes up to 256K, which is probably OK.
7544 	 * If the chunk size is greater, user-space should request more
7545 	 * stripe_heads first.
7546 	 */
7547 	struct r5conf *conf = mddev->private;
7548 	if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7549 	    > conf->min_nr_stripes ||
7550 	    ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7551 	    > conf->min_nr_stripes) {
7552 		pr_warn("md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7553 			mdname(mddev),
7554 			((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7555 			 / STRIPE_SIZE)*4);
7556 		return 0;
7557 	}
7558 	return 1;
7559 }
7560 
7561 static int check_reshape(struct mddev *mddev)
7562 {
7563 	struct r5conf *conf = mddev->private;
7564 
7565 	if (conf->log)
7566 		return -EINVAL;
7567 	if (mddev->delta_disks == 0 &&
7568 	    mddev->new_layout == mddev->layout &&
7569 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
7570 		return 0; /* nothing to do */
7571 	if (has_failed(conf))
7572 		return -EINVAL;
7573 	if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7574 		/* We might be able to shrink, but the devices must
7575 		 * be made bigger first.
7576 		 * For raid6, 4 is the minimum size.
7577 		 * Otherwise 2 is the minimum
7578 		 */
7579 		int min = 2;
7580 		if (mddev->level == 6)
7581 			min = 4;
7582 		if (mddev->raid_disks + mddev->delta_disks < min)
7583 			return -EINVAL;
7584 	}
7585 
7586 	if (!check_stripe_cache(mddev))
7587 		return -ENOSPC;
7588 
7589 	if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7590 	    mddev->delta_disks > 0)
7591 		if (resize_chunks(conf,
7592 				  conf->previous_raid_disks
7593 				  + max(0, mddev->delta_disks),
7594 				  max(mddev->new_chunk_sectors,
7595 				      mddev->chunk_sectors)
7596 			    ) < 0)
7597 			return -ENOMEM;
7598 	return resize_stripes(conf, (conf->previous_raid_disks
7599 				     + mddev->delta_disks));
7600 }
7601 
7602 static int raid5_start_reshape(struct mddev *mddev)
7603 {
7604 	struct r5conf *conf = mddev->private;
7605 	struct md_rdev *rdev;
7606 	int spares = 0;
7607 	unsigned long flags;
7608 
7609 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7610 		return -EBUSY;
7611 
7612 	if (!check_stripe_cache(mddev))
7613 		return -ENOSPC;
7614 
7615 	if (has_failed(conf))
7616 		return -EINVAL;
7617 
7618 	rdev_for_each(rdev, mddev) {
7619 		if (!test_bit(In_sync, &rdev->flags)
7620 		    && !test_bit(Faulty, &rdev->flags))
7621 			spares++;
7622 	}
7623 
7624 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7625 		/* Not enough devices even to make a degraded array
7626 		 * of that size
7627 		 */
7628 		return -EINVAL;
7629 
7630 	/* Refuse to reduce size of the array.  Any reductions in
7631 	 * array size must be through explicit setting of array_size
7632 	 * attribute.
7633 	 */
7634 	if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7635 	    < mddev->array_sectors) {
7636 		pr_warn("md/raid:%s: array size must be reduced before number of disks\n",
7637 			mdname(mddev));
7638 		return -EINVAL;
7639 	}
7640 
7641 	atomic_set(&conf->reshape_stripes, 0);
7642 	spin_lock_irq(&conf->device_lock);
7643 	write_seqcount_begin(&conf->gen_lock);
7644 	conf->previous_raid_disks = conf->raid_disks;
7645 	conf->raid_disks += mddev->delta_disks;
7646 	conf->prev_chunk_sectors = conf->chunk_sectors;
7647 	conf->chunk_sectors = mddev->new_chunk_sectors;
7648 	conf->prev_algo = conf->algorithm;
7649 	conf->algorithm = mddev->new_layout;
7650 	conf->generation++;
7651 	/* Code that selects data_offset needs to see the generation update
7652 	 * if reshape_progress has been set - so a memory barrier needed.
7653 	 */
7654 	smp_mb();
7655 	if (mddev->reshape_backwards)
7656 		conf->reshape_progress = raid5_size(mddev, 0, 0);
7657 	else
7658 		conf->reshape_progress = 0;
7659 	conf->reshape_safe = conf->reshape_progress;
7660 	write_seqcount_end(&conf->gen_lock);
7661 	spin_unlock_irq(&conf->device_lock);
7662 
7663 	/* Now make sure any requests that proceeded on the assumption
7664 	 * the reshape wasn't running - like Discard or Read - have
7665 	 * completed.
7666 	 */
7667 	mddev_suspend(mddev);
7668 	mddev_resume(mddev);
7669 
7670 	/* Add some new drives, as many as will fit.
7671 	 * We know there are enough to make the newly sized array work.
7672 	 * Don't add devices if we are reducing the number of
7673 	 * devices in the array.  This is because it is not possible
7674 	 * to correctly record the "partially reconstructed" state of
7675 	 * such devices during the reshape and confusion could result.
7676 	 */
7677 	if (mddev->delta_disks >= 0) {
7678 		rdev_for_each(rdev, mddev)
7679 			if (rdev->raid_disk < 0 &&
7680 			    !test_bit(Faulty, &rdev->flags)) {
7681 				if (raid5_add_disk(mddev, rdev) == 0) {
7682 					if (rdev->raid_disk
7683 					    >= conf->previous_raid_disks)
7684 						set_bit(In_sync, &rdev->flags);
7685 					else
7686 						rdev->recovery_offset = 0;
7687 
7688 					if (sysfs_link_rdev(mddev, rdev))
7689 						/* Failure here is OK */;
7690 				}
7691 			} else if (rdev->raid_disk >= conf->previous_raid_disks
7692 				   && !test_bit(Faulty, &rdev->flags)) {
7693 				/* This is a spare that was manually added */
7694 				set_bit(In_sync, &rdev->flags);
7695 			}
7696 
7697 		/* When a reshape changes the number of devices,
7698 		 * ->degraded is measured against the larger of the
7699 		 * pre and post number of devices.
7700 		 */
7701 		spin_lock_irqsave(&conf->device_lock, flags);
7702 		mddev->degraded = raid5_calc_degraded(conf);
7703 		spin_unlock_irqrestore(&conf->device_lock, flags);
7704 	}
7705 	mddev->raid_disks = conf->raid_disks;
7706 	mddev->reshape_position = conf->reshape_progress;
7707 	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
7708 
7709 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7710 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7711 	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7712 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7713 	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7714 	mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7715 						"reshape");
7716 	if (!mddev->sync_thread) {
7717 		mddev->recovery = 0;
7718 		spin_lock_irq(&conf->device_lock);
7719 		write_seqcount_begin(&conf->gen_lock);
7720 		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7721 		mddev->new_chunk_sectors =
7722 			conf->chunk_sectors = conf->prev_chunk_sectors;
7723 		mddev->new_layout = conf->algorithm = conf->prev_algo;
7724 		rdev_for_each(rdev, mddev)
7725 			rdev->new_data_offset = rdev->data_offset;
7726 		smp_wmb();
7727 		conf->generation --;
7728 		conf->reshape_progress = MaxSector;
7729 		mddev->reshape_position = MaxSector;
7730 		write_seqcount_end(&conf->gen_lock);
7731 		spin_unlock_irq(&conf->device_lock);
7732 		return -EAGAIN;
7733 	}
7734 	conf->reshape_checkpoint = jiffies;
7735 	md_wakeup_thread(mddev->sync_thread);
7736 	md_new_event(mddev);
7737 	return 0;
7738 }
7739 
7740 /* This is called from the reshape thread and should make any
7741  * changes needed in 'conf'
7742  */
7743 static void end_reshape(struct r5conf *conf)
7744 {
7745 
7746 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7747 		struct md_rdev *rdev;
7748 
7749 		spin_lock_irq(&conf->device_lock);
7750 		conf->previous_raid_disks = conf->raid_disks;
7751 		rdev_for_each(rdev, conf->mddev)
7752 			rdev->data_offset = rdev->new_data_offset;
7753 		smp_wmb();
7754 		conf->reshape_progress = MaxSector;
7755 		conf->mddev->reshape_position = MaxSector;
7756 		spin_unlock_irq(&conf->device_lock);
7757 		wake_up(&conf->wait_for_overlap);
7758 
7759 		/* read-ahead size must cover two whole stripes, which is
7760 		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7761 		 */
7762 		if (conf->mddev->queue) {
7763 			int data_disks = conf->raid_disks - conf->max_degraded;
7764 			int stripe = data_disks * ((conf->chunk_sectors << 9)
7765 						   / PAGE_SIZE);
7766 			if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7767 				conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7768 		}
7769 	}
7770 }
7771 
7772 /* This is called from the raid5d thread with mddev_lock held.
7773  * It makes config changes to the device.
7774  */
7775 static void raid5_finish_reshape(struct mddev *mddev)
7776 {
7777 	struct r5conf *conf = mddev->private;
7778 
7779 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7780 
7781 		if (mddev->delta_disks > 0) {
7782 			md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7783 			if (mddev->queue) {
7784 				set_capacity(mddev->gendisk, mddev->array_sectors);
7785 				revalidate_disk(mddev->gendisk);
7786 			}
7787 		} else {
7788 			int d;
7789 			spin_lock_irq(&conf->device_lock);
7790 			mddev->degraded = raid5_calc_degraded(conf);
7791 			spin_unlock_irq(&conf->device_lock);
7792 			for (d = conf->raid_disks ;
7793 			     d < conf->raid_disks - mddev->delta_disks;
7794 			     d++) {
7795 				struct md_rdev *rdev = conf->disks[d].rdev;
7796 				if (rdev)
7797 					clear_bit(In_sync, &rdev->flags);
7798 				rdev = conf->disks[d].replacement;
7799 				if (rdev)
7800 					clear_bit(In_sync, &rdev->flags);
7801 			}
7802 		}
7803 		mddev->layout = conf->algorithm;
7804 		mddev->chunk_sectors = conf->chunk_sectors;
7805 		mddev->reshape_position = MaxSector;
7806 		mddev->delta_disks = 0;
7807 		mddev->reshape_backwards = 0;
7808 	}
7809 }
7810 
7811 static void raid5_quiesce(struct mddev *mddev, int state)
7812 {
7813 	struct r5conf *conf = mddev->private;
7814 
7815 	switch(state) {
7816 	case 2: /* resume for a suspend */
7817 		wake_up(&conf->wait_for_overlap);
7818 		break;
7819 
7820 	case 1: /* stop all writes */
7821 		lock_all_device_hash_locks_irq(conf);
7822 		/* '2' tells resync/reshape to pause so that all
7823 		 * active stripes can drain
7824 		 */
7825 		r5c_flush_cache(conf, INT_MAX);
7826 		conf->quiesce = 2;
7827 		wait_event_cmd(conf->wait_for_quiescent,
7828 				    atomic_read(&conf->active_stripes) == 0 &&
7829 				    atomic_read(&conf->active_aligned_reads) == 0,
7830 				    unlock_all_device_hash_locks_irq(conf),
7831 				    lock_all_device_hash_locks_irq(conf));
7832 		conf->quiesce = 1;
7833 		unlock_all_device_hash_locks_irq(conf);
7834 		/* allow reshape to continue */
7835 		wake_up(&conf->wait_for_overlap);
7836 		break;
7837 
7838 	case 0: /* re-enable writes */
7839 		lock_all_device_hash_locks_irq(conf);
7840 		conf->quiesce = 0;
7841 		wake_up(&conf->wait_for_quiescent);
7842 		wake_up(&conf->wait_for_overlap);
7843 		unlock_all_device_hash_locks_irq(conf);
7844 		break;
7845 	}
7846 	r5l_quiesce(conf->log, state);
7847 }
7848 
7849 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
7850 {
7851 	struct r0conf *raid0_conf = mddev->private;
7852 	sector_t sectors;
7853 
7854 	/* for raid0 takeover only one zone is supported */
7855 	if (raid0_conf->nr_strip_zones > 1) {
7856 		pr_warn("md/raid:%s: cannot takeover raid0 with more than one zone.\n",
7857 			mdname(mddev));
7858 		return ERR_PTR(-EINVAL);
7859 	}
7860 
7861 	sectors = raid0_conf->strip_zone[0].zone_end;
7862 	sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
7863 	mddev->dev_sectors = sectors;
7864 	mddev->new_level = level;
7865 	mddev->new_layout = ALGORITHM_PARITY_N;
7866 	mddev->new_chunk_sectors = mddev->chunk_sectors;
7867 	mddev->raid_disks += 1;
7868 	mddev->delta_disks = 1;
7869 	/* make sure it will be not marked as dirty */
7870 	mddev->recovery_cp = MaxSector;
7871 
7872 	return setup_conf(mddev);
7873 }
7874 
7875 static void *raid5_takeover_raid1(struct mddev *mddev)
7876 {
7877 	int chunksect;
7878 	void *ret;
7879 
7880 	if (mddev->raid_disks != 2 ||
7881 	    mddev->degraded > 1)
7882 		return ERR_PTR(-EINVAL);
7883 
7884 	/* Should check if there are write-behind devices? */
7885 
7886 	chunksect = 64*2; /* 64K by default */
7887 
7888 	/* The array must be an exact multiple of chunksize */
7889 	while (chunksect && (mddev->array_sectors & (chunksect-1)))
7890 		chunksect >>= 1;
7891 
7892 	if ((chunksect<<9) < STRIPE_SIZE)
7893 		/* array size does not allow a suitable chunk size */
7894 		return ERR_PTR(-EINVAL);
7895 
7896 	mddev->new_level = 5;
7897 	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
7898 	mddev->new_chunk_sectors = chunksect;
7899 
7900 	ret = setup_conf(mddev);
7901 	if (!IS_ERR(ret))
7902 		mddev_clear_unsupported_flags(mddev,
7903 			UNSUPPORTED_MDDEV_FLAGS);
7904 	return ret;
7905 }
7906 
7907 static void *raid5_takeover_raid6(struct mddev *mddev)
7908 {
7909 	int new_layout;
7910 
7911 	switch (mddev->layout) {
7912 	case ALGORITHM_LEFT_ASYMMETRIC_6:
7913 		new_layout = ALGORITHM_LEFT_ASYMMETRIC;
7914 		break;
7915 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
7916 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
7917 		break;
7918 	case ALGORITHM_LEFT_SYMMETRIC_6:
7919 		new_layout = ALGORITHM_LEFT_SYMMETRIC;
7920 		break;
7921 	case ALGORITHM_RIGHT_SYMMETRIC_6:
7922 		new_layout = ALGORITHM_RIGHT_SYMMETRIC;
7923 		break;
7924 	case ALGORITHM_PARITY_0_6:
7925 		new_layout = ALGORITHM_PARITY_0;
7926 		break;
7927 	case ALGORITHM_PARITY_N:
7928 		new_layout = ALGORITHM_PARITY_N;
7929 		break;
7930 	default:
7931 		return ERR_PTR(-EINVAL);
7932 	}
7933 	mddev->new_level = 5;
7934 	mddev->new_layout = new_layout;
7935 	mddev->delta_disks = -1;
7936 	mddev->raid_disks -= 1;
7937 	return setup_conf(mddev);
7938 }
7939 
7940 static int raid5_check_reshape(struct mddev *mddev)
7941 {
7942 	/* For a 2-drive array, the layout and chunk size can be changed
7943 	 * immediately as not restriping is needed.
7944 	 * For larger arrays we record the new value - after validation
7945 	 * to be used by a reshape pass.
7946 	 */
7947 	struct r5conf *conf = mddev->private;
7948 	int new_chunk = mddev->new_chunk_sectors;
7949 
7950 	if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
7951 		return -EINVAL;
7952 	if (new_chunk > 0) {
7953 		if (!is_power_of_2(new_chunk))
7954 			return -EINVAL;
7955 		if (new_chunk < (PAGE_SIZE>>9))
7956 			return -EINVAL;
7957 		if (mddev->array_sectors & (new_chunk-1))
7958 			/* not factor of array size */
7959 			return -EINVAL;
7960 	}
7961 
7962 	/* They look valid */
7963 
7964 	if (mddev->raid_disks == 2) {
7965 		/* can make the change immediately */
7966 		if (mddev->new_layout >= 0) {
7967 			conf->algorithm = mddev->new_layout;
7968 			mddev->layout = mddev->new_layout;
7969 		}
7970 		if (new_chunk > 0) {
7971 			conf->chunk_sectors = new_chunk ;
7972 			mddev->chunk_sectors = new_chunk;
7973 		}
7974 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
7975 		md_wakeup_thread(mddev->thread);
7976 	}
7977 	return check_reshape(mddev);
7978 }
7979 
7980 static int raid6_check_reshape(struct mddev *mddev)
7981 {
7982 	int new_chunk = mddev->new_chunk_sectors;
7983 
7984 	if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
7985 		return -EINVAL;
7986 	if (new_chunk > 0) {
7987 		if (!is_power_of_2(new_chunk))
7988 			return -EINVAL;
7989 		if (new_chunk < (PAGE_SIZE >> 9))
7990 			return -EINVAL;
7991 		if (mddev->array_sectors & (new_chunk-1))
7992 			/* not factor of array size */
7993 			return -EINVAL;
7994 	}
7995 
7996 	/* They look valid */
7997 	return check_reshape(mddev);
7998 }
7999 
8000 static void *raid5_takeover(struct mddev *mddev)
8001 {
8002 	/* raid5 can take over:
8003 	 *  raid0 - if there is only one strip zone - make it a raid4 layout
8004 	 *  raid1 - if there are two drives.  We need to know the chunk size
8005 	 *  raid4 - trivial - just use a raid4 layout.
8006 	 *  raid6 - Providing it is a *_6 layout
8007 	 */
8008 	if (mddev->level == 0)
8009 		return raid45_takeover_raid0(mddev, 5);
8010 	if (mddev->level == 1)
8011 		return raid5_takeover_raid1(mddev);
8012 	if (mddev->level == 4) {
8013 		mddev->new_layout = ALGORITHM_PARITY_N;
8014 		mddev->new_level = 5;
8015 		return setup_conf(mddev);
8016 	}
8017 	if (mddev->level == 6)
8018 		return raid5_takeover_raid6(mddev);
8019 
8020 	return ERR_PTR(-EINVAL);
8021 }
8022 
8023 static void *raid4_takeover(struct mddev *mddev)
8024 {
8025 	/* raid4 can take over:
8026 	 *  raid0 - if there is only one strip zone
8027 	 *  raid5 - if layout is right
8028 	 */
8029 	if (mddev->level == 0)
8030 		return raid45_takeover_raid0(mddev, 4);
8031 	if (mddev->level == 5 &&
8032 	    mddev->layout == ALGORITHM_PARITY_N) {
8033 		mddev->new_layout = 0;
8034 		mddev->new_level = 4;
8035 		return setup_conf(mddev);
8036 	}
8037 	return ERR_PTR(-EINVAL);
8038 }
8039 
8040 static struct md_personality raid5_personality;
8041 
8042 static void *raid6_takeover(struct mddev *mddev)
8043 {
8044 	/* Currently can only take over a raid5.  We map the
8045 	 * personality to an equivalent raid6 personality
8046 	 * with the Q block at the end.
8047 	 */
8048 	int new_layout;
8049 
8050 	if (mddev->pers != &raid5_personality)
8051 		return ERR_PTR(-EINVAL);
8052 	if (mddev->degraded > 1)
8053 		return ERR_PTR(-EINVAL);
8054 	if (mddev->raid_disks > 253)
8055 		return ERR_PTR(-EINVAL);
8056 	if (mddev->raid_disks < 3)
8057 		return ERR_PTR(-EINVAL);
8058 
8059 	switch (mddev->layout) {
8060 	case ALGORITHM_LEFT_ASYMMETRIC:
8061 		new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
8062 		break;
8063 	case ALGORITHM_RIGHT_ASYMMETRIC:
8064 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
8065 		break;
8066 	case ALGORITHM_LEFT_SYMMETRIC:
8067 		new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
8068 		break;
8069 	case ALGORITHM_RIGHT_SYMMETRIC:
8070 		new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
8071 		break;
8072 	case ALGORITHM_PARITY_0:
8073 		new_layout = ALGORITHM_PARITY_0_6;
8074 		break;
8075 	case ALGORITHM_PARITY_N:
8076 		new_layout = ALGORITHM_PARITY_N;
8077 		break;
8078 	default:
8079 		return ERR_PTR(-EINVAL);
8080 	}
8081 	mddev->new_level = 6;
8082 	mddev->new_layout = new_layout;
8083 	mddev->delta_disks = 1;
8084 	mddev->raid_disks += 1;
8085 	return setup_conf(mddev);
8086 }
8087 
8088 static struct md_personality raid6_personality =
8089 {
8090 	.name		= "raid6",
8091 	.level		= 6,
8092 	.owner		= THIS_MODULE,
8093 	.make_request	= raid5_make_request,
8094 	.run		= raid5_run,
8095 	.free		= raid5_free,
8096 	.status		= raid5_status,
8097 	.error_handler	= raid5_error,
8098 	.hot_add_disk	= raid5_add_disk,
8099 	.hot_remove_disk= raid5_remove_disk,
8100 	.spare_active	= raid5_spare_active,
8101 	.sync_request	= raid5_sync_request,
8102 	.resize		= raid5_resize,
8103 	.size		= raid5_size,
8104 	.check_reshape	= raid6_check_reshape,
8105 	.start_reshape  = raid5_start_reshape,
8106 	.finish_reshape = raid5_finish_reshape,
8107 	.quiesce	= raid5_quiesce,
8108 	.takeover	= raid6_takeover,
8109 	.congested	= raid5_congested,
8110 };
8111 static struct md_personality raid5_personality =
8112 {
8113 	.name		= "raid5",
8114 	.level		= 5,
8115 	.owner		= THIS_MODULE,
8116 	.make_request	= raid5_make_request,
8117 	.run		= raid5_run,
8118 	.free		= raid5_free,
8119 	.status		= raid5_status,
8120 	.error_handler	= raid5_error,
8121 	.hot_add_disk	= raid5_add_disk,
8122 	.hot_remove_disk= raid5_remove_disk,
8123 	.spare_active	= raid5_spare_active,
8124 	.sync_request	= raid5_sync_request,
8125 	.resize		= raid5_resize,
8126 	.size		= raid5_size,
8127 	.check_reshape	= raid5_check_reshape,
8128 	.start_reshape  = raid5_start_reshape,
8129 	.finish_reshape = raid5_finish_reshape,
8130 	.quiesce	= raid5_quiesce,
8131 	.takeover	= raid5_takeover,
8132 	.congested	= raid5_congested,
8133 };
8134 
8135 static struct md_personality raid4_personality =
8136 {
8137 	.name		= "raid4",
8138 	.level		= 4,
8139 	.owner		= THIS_MODULE,
8140 	.make_request	= raid5_make_request,
8141 	.run		= raid5_run,
8142 	.free		= raid5_free,
8143 	.status		= raid5_status,
8144 	.error_handler	= raid5_error,
8145 	.hot_add_disk	= raid5_add_disk,
8146 	.hot_remove_disk= raid5_remove_disk,
8147 	.spare_active	= raid5_spare_active,
8148 	.sync_request	= raid5_sync_request,
8149 	.resize		= raid5_resize,
8150 	.size		= raid5_size,
8151 	.check_reshape	= raid5_check_reshape,
8152 	.start_reshape  = raid5_start_reshape,
8153 	.finish_reshape = raid5_finish_reshape,
8154 	.quiesce	= raid5_quiesce,
8155 	.takeover	= raid4_takeover,
8156 	.congested	= raid5_congested,
8157 };
8158 
8159 static int __init raid5_init(void)
8160 {
8161 	int ret;
8162 
8163 	raid5_wq = alloc_workqueue("raid5wq",
8164 		WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
8165 	if (!raid5_wq)
8166 		return -ENOMEM;
8167 
8168 	ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
8169 				      "md/raid5:prepare",
8170 				      raid456_cpu_up_prepare,
8171 				      raid456_cpu_dead);
8172 	if (ret) {
8173 		destroy_workqueue(raid5_wq);
8174 		return ret;
8175 	}
8176 	register_md_personality(&raid6_personality);
8177 	register_md_personality(&raid5_personality);
8178 	register_md_personality(&raid4_personality);
8179 	return 0;
8180 }
8181 
8182 static void raid5_exit(void)
8183 {
8184 	unregister_md_personality(&raid6_personality);
8185 	unregister_md_personality(&raid5_personality);
8186 	unregister_md_personality(&raid4_personality);
8187 	cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
8188 	destroy_workqueue(raid5_wq);
8189 }
8190 
8191 module_init(raid5_init);
8192 module_exit(raid5_exit);
8193 MODULE_LICENSE("GPL");
8194 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
8195 MODULE_ALIAS("md-personality-4"); /* RAID5 */
8196 MODULE_ALIAS("md-raid5");
8197 MODULE_ALIAS("md-raid4");
8198 MODULE_ALIAS("md-level-5");
8199 MODULE_ALIAS("md-level-4");
8200 MODULE_ALIAS("md-personality-8"); /* RAID6 */
8201 MODULE_ALIAS("md-raid6");
8202 MODULE_ALIAS("md-level-6");
8203 
8204 /* This used to be two separate modules, they were: */
8205 MODULE_ALIAS("raid5");
8206 MODULE_ALIAS("raid6");
8207