xref: /openbmc/linux/drivers/md/raid5.c (revision ca481398)
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 <linux/sched/signal.h>
59 
60 #include <trace/events/block.h>
61 #include <linux/list_sort.h>
62 
63 #include "md.h"
64 #include "raid5.h"
65 #include "raid0.h"
66 #include "bitmap.h"
67 #include "raid5-log.h"
68 
69 #define UNSUPPORTED_MDDEV_FLAGS	(1L << MD_FAILFAST_SUPPORTED)
70 
71 #define cpu_to_group(cpu) cpu_to_node(cpu)
72 #define ANY_GROUP NUMA_NO_NODE
73 
74 static bool devices_handle_discard_safely = false;
75 module_param(devices_handle_discard_safely, bool, 0644);
76 MODULE_PARM_DESC(devices_handle_discard_safely,
77 		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
78 static struct workqueue_struct *raid5_wq;
79 
80 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
81 {
82 	int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
83 	return &conf->stripe_hashtbl[hash];
84 }
85 
86 static inline int stripe_hash_locks_hash(sector_t sect)
87 {
88 	return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
89 }
90 
91 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
92 {
93 	spin_lock_irq(conf->hash_locks + hash);
94 	spin_lock(&conf->device_lock);
95 }
96 
97 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
98 {
99 	spin_unlock(&conf->device_lock);
100 	spin_unlock_irq(conf->hash_locks + hash);
101 }
102 
103 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
104 {
105 	int i;
106 	spin_lock_irq(conf->hash_locks);
107 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
108 		spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
109 	spin_lock(&conf->device_lock);
110 }
111 
112 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
113 {
114 	int i;
115 	spin_unlock(&conf->device_lock);
116 	for (i = NR_STRIPE_HASH_LOCKS - 1; i; i--)
117 		spin_unlock(conf->hash_locks + i);
118 	spin_unlock_irq(conf->hash_locks);
119 }
120 
121 /* Find first data disk in a raid6 stripe */
122 static inline int raid6_d0(struct stripe_head *sh)
123 {
124 	if (sh->ddf_layout)
125 		/* ddf always start from first device */
126 		return 0;
127 	/* md starts just after Q block */
128 	if (sh->qd_idx == sh->disks - 1)
129 		return 0;
130 	else
131 		return sh->qd_idx + 1;
132 }
133 static inline int raid6_next_disk(int disk, int raid_disks)
134 {
135 	disk++;
136 	return (disk < raid_disks) ? disk : 0;
137 }
138 
139 /* When walking through the disks in a raid5, starting at raid6_d0,
140  * We need to map each disk to a 'slot', where the data disks are slot
141  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
142  * is raid_disks-1.  This help does that mapping.
143  */
144 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
145 			     int *count, int syndrome_disks)
146 {
147 	int slot = *count;
148 
149 	if (sh->ddf_layout)
150 		(*count)++;
151 	if (idx == sh->pd_idx)
152 		return syndrome_disks;
153 	if (idx == sh->qd_idx)
154 		return syndrome_disks + 1;
155 	if (!sh->ddf_layout)
156 		(*count)++;
157 	return slot;
158 }
159 
160 static void print_raid5_conf (struct r5conf *conf);
161 
162 static int stripe_operations_active(struct stripe_head *sh)
163 {
164 	return sh->check_state || sh->reconstruct_state ||
165 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
166 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
167 }
168 
169 static bool stripe_is_lowprio(struct stripe_head *sh)
170 {
171 	return (test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state) ||
172 		test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) &&
173 	       !test_bit(STRIPE_R5C_CACHING, &sh->state);
174 }
175 
176 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
177 {
178 	struct r5conf *conf = sh->raid_conf;
179 	struct r5worker_group *group;
180 	int thread_cnt;
181 	int i, cpu = sh->cpu;
182 
183 	if (!cpu_online(cpu)) {
184 		cpu = cpumask_any(cpu_online_mask);
185 		sh->cpu = cpu;
186 	}
187 
188 	if (list_empty(&sh->lru)) {
189 		struct r5worker_group *group;
190 		group = conf->worker_groups + cpu_to_group(cpu);
191 		if (stripe_is_lowprio(sh))
192 			list_add_tail(&sh->lru, &group->loprio_list);
193 		else
194 			list_add_tail(&sh->lru, &group->handle_list);
195 		group->stripes_cnt++;
196 		sh->group = group;
197 	}
198 
199 	if (conf->worker_cnt_per_group == 0) {
200 		md_wakeup_thread(conf->mddev->thread);
201 		return;
202 	}
203 
204 	group = conf->worker_groups + cpu_to_group(sh->cpu);
205 
206 	group->workers[0].working = true;
207 	/* at least one worker should run to avoid race */
208 	queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
209 
210 	thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
211 	/* wakeup more workers */
212 	for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
213 		if (group->workers[i].working == false) {
214 			group->workers[i].working = true;
215 			queue_work_on(sh->cpu, raid5_wq,
216 				      &group->workers[i].work);
217 			thread_cnt--;
218 		}
219 	}
220 }
221 
222 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
223 			      struct list_head *temp_inactive_list)
224 {
225 	int i;
226 	int injournal = 0;	/* number of date pages with R5_InJournal */
227 
228 	BUG_ON(!list_empty(&sh->lru));
229 	BUG_ON(atomic_read(&conf->active_stripes)==0);
230 
231 	if (r5c_is_writeback(conf->log))
232 		for (i = sh->disks; i--; )
233 			if (test_bit(R5_InJournal, &sh->dev[i].flags))
234 				injournal++;
235 	/*
236 	 * In the following cases, the stripe cannot be released to cached
237 	 * lists. Therefore, we make the stripe write out and set
238 	 * STRIPE_HANDLE:
239 	 *   1. when quiesce in r5c write back;
240 	 *   2. when resync is requested fot the stripe.
241 	 */
242 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) ||
243 	    (conf->quiesce && r5c_is_writeback(conf->log) &&
244 	     !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0)) {
245 		if (test_bit(STRIPE_R5C_CACHING, &sh->state))
246 			r5c_make_stripe_write_out(sh);
247 		set_bit(STRIPE_HANDLE, &sh->state);
248 	}
249 
250 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
251 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
252 		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
253 			list_add_tail(&sh->lru, &conf->delayed_list);
254 		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
255 			   sh->bm_seq - conf->seq_write > 0)
256 			list_add_tail(&sh->lru, &conf->bitmap_list);
257 		else {
258 			clear_bit(STRIPE_DELAYED, &sh->state);
259 			clear_bit(STRIPE_BIT_DELAY, &sh->state);
260 			if (conf->worker_cnt_per_group == 0) {
261 				if (stripe_is_lowprio(sh))
262 					list_add_tail(&sh->lru,
263 							&conf->loprio_list);
264 				else
265 					list_add_tail(&sh->lru,
266 							&conf->handle_list);
267 			} else {
268 				raid5_wakeup_stripe_thread(sh);
269 				return;
270 			}
271 		}
272 		md_wakeup_thread(conf->mddev->thread);
273 	} else {
274 		BUG_ON(stripe_operations_active(sh));
275 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
276 			if (atomic_dec_return(&conf->preread_active_stripes)
277 			    < IO_THRESHOLD)
278 				md_wakeup_thread(conf->mddev->thread);
279 		atomic_dec(&conf->active_stripes);
280 		if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
281 			if (!r5c_is_writeback(conf->log))
282 				list_add_tail(&sh->lru, temp_inactive_list);
283 			else {
284 				WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
285 				if (injournal == 0)
286 					list_add_tail(&sh->lru, temp_inactive_list);
287 				else if (injournal == conf->raid_disks - conf->max_degraded) {
288 					/* full stripe */
289 					if (!test_and_set_bit(STRIPE_R5C_FULL_STRIPE, &sh->state))
290 						atomic_inc(&conf->r5c_cached_full_stripes);
291 					if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
292 						atomic_dec(&conf->r5c_cached_partial_stripes);
293 					list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
294 					r5c_check_cached_full_stripe(conf);
295 				} else
296 					/*
297 					 * STRIPE_R5C_PARTIAL_STRIPE is set in
298 					 * r5c_try_caching_write(). No need to
299 					 * set it again.
300 					 */
301 					list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
302 			}
303 		}
304 	}
305 }
306 
307 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
308 			     struct list_head *temp_inactive_list)
309 {
310 	if (atomic_dec_and_test(&sh->count))
311 		do_release_stripe(conf, sh, temp_inactive_list);
312 }
313 
314 /*
315  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
316  *
317  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
318  * given time. Adding stripes only takes device lock, while deleting stripes
319  * only takes hash lock.
320  */
321 static void release_inactive_stripe_list(struct r5conf *conf,
322 					 struct list_head *temp_inactive_list,
323 					 int hash)
324 {
325 	int size;
326 	bool do_wakeup = false;
327 	unsigned long flags;
328 
329 	if (hash == NR_STRIPE_HASH_LOCKS) {
330 		size = NR_STRIPE_HASH_LOCKS;
331 		hash = NR_STRIPE_HASH_LOCKS - 1;
332 	} else
333 		size = 1;
334 	while (size) {
335 		struct list_head *list = &temp_inactive_list[size - 1];
336 
337 		/*
338 		 * We don't hold any lock here yet, raid5_get_active_stripe() might
339 		 * remove stripes from the list
340 		 */
341 		if (!list_empty_careful(list)) {
342 			spin_lock_irqsave(conf->hash_locks + hash, flags);
343 			if (list_empty(conf->inactive_list + hash) &&
344 			    !list_empty(list))
345 				atomic_dec(&conf->empty_inactive_list_nr);
346 			list_splice_tail_init(list, conf->inactive_list + hash);
347 			do_wakeup = true;
348 			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
349 		}
350 		size--;
351 		hash--;
352 	}
353 
354 	if (do_wakeup) {
355 		wake_up(&conf->wait_for_stripe);
356 		if (atomic_read(&conf->active_stripes) == 0)
357 			wake_up(&conf->wait_for_quiescent);
358 		if (conf->retry_read_aligned)
359 			md_wakeup_thread(conf->mddev->thread);
360 	}
361 }
362 
363 /* should hold conf->device_lock already */
364 static int release_stripe_list(struct r5conf *conf,
365 			       struct list_head *temp_inactive_list)
366 {
367 	struct stripe_head *sh, *t;
368 	int count = 0;
369 	struct llist_node *head;
370 
371 	head = llist_del_all(&conf->released_stripes);
372 	head = llist_reverse_order(head);
373 	llist_for_each_entry_safe(sh, t, head, release_list) {
374 		int hash;
375 
376 		/* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
377 		smp_mb();
378 		clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
379 		/*
380 		 * Don't worry the bit is set here, because if the bit is set
381 		 * again, the count is always > 1. This is true for
382 		 * STRIPE_ON_UNPLUG_LIST bit too.
383 		 */
384 		hash = sh->hash_lock_index;
385 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
386 		count++;
387 	}
388 
389 	return count;
390 }
391 
392 void raid5_release_stripe(struct stripe_head *sh)
393 {
394 	struct r5conf *conf = sh->raid_conf;
395 	unsigned long flags;
396 	struct list_head list;
397 	int hash;
398 	bool wakeup;
399 
400 	/* Avoid release_list until the last reference.
401 	 */
402 	if (atomic_add_unless(&sh->count, -1, 1))
403 		return;
404 
405 	if (unlikely(!conf->mddev->thread) ||
406 		test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
407 		goto slow_path;
408 	wakeup = llist_add(&sh->release_list, &conf->released_stripes);
409 	if (wakeup)
410 		md_wakeup_thread(conf->mddev->thread);
411 	return;
412 slow_path:
413 	local_irq_save(flags);
414 	/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
415 	if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
416 		INIT_LIST_HEAD(&list);
417 		hash = sh->hash_lock_index;
418 		do_release_stripe(conf, sh, &list);
419 		spin_unlock(&conf->device_lock);
420 		release_inactive_stripe_list(conf, &list, hash);
421 	}
422 	local_irq_restore(flags);
423 }
424 
425 static inline void remove_hash(struct stripe_head *sh)
426 {
427 	pr_debug("remove_hash(), stripe %llu\n",
428 		(unsigned long long)sh->sector);
429 
430 	hlist_del_init(&sh->hash);
431 }
432 
433 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
434 {
435 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
436 
437 	pr_debug("insert_hash(), stripe %llu\n",
438 		(unsigned long long)sh->sector);
439 
440 	hlist_add_head(&sh->hash, hp);
441 }
442 
443 /* find an idle stripe, make sure it is unhashed, and return it. */
444 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
445 {
446 	struct stripe_head *sh = NULL;
447 	struct list_head *first;
448 
449 	if (list_empty(conf->inactive_list + hash))
450 		goto out;
451 	first = (conf->inactive_list + hash)->next;
452 	sh = list_entry(first, struct stripe_head, lru);
453 	list_del_init(first);
454 	remove_hash(sh);
455 	atomic_inc(&conf->active_stripes);
456 	BUG_ON(hash != sh->hash_lock_index);
457 	if (list_empty(conf->inactive_list + hash))
458 		atomic_inc(&conf->empty_inactive_list_nr);
459 out:
460 	return sh;
461 }
462 
463 static void shrink_buffers(struct stripe_head *sh)
464 {
465 	struct page *p;
466 	int i;
467 	int num = sh->raid_conf->pool_size;
468 
469 	for (i = 0; i < num ; i++) {
470 		WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
471 		p = sh->dev[i].page;
472 		if (!p)
473 			continue;
474 		sh->dev[i].page = NULL;
475 		put_page(p);
476 	}
477 }
478 
479 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
480 {
481 	int i;
482 	int num = sh->raid_conf->pool_size;
483 
484 	for (i = 0; i < num; i++) {
485 		struct page *page;
486 
487 		if (!(page = alloc_page(gfp))) {
488 			return 1;
489 		}
490 		sh->dev[i].page = page;
491 		sh->dev[i].orig_page = page;
492 	}
493 
494 	return 0;
495 }
496 
497 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
498 			    struct stripe_head *sh);
499 
500 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
501 {
502 	struct r5conf *conf = sh->raid_conf;
503 	int i, seq;
504 
505 	BUG_ON(atomic_read(&sh->count) != 0);
506 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
507 	BUG_ON(stripe_operations_active(sh));
508 	BUG_ON(sh->batch_head);
509 
510 	pr_debug("init_stripe called, stripe %llu\n",
511 		(unsigned long long)sector);
512 retry:
513 	seq = read_seqcount_begin(&conf->gen_lock);
514 	sh->generation = conf->generation - previous;
515 	sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
516 	sh->sector = sector;
517 	stripe_set_idx(sector, conf, previous, sh);
518 	sh->state = 0;
519 
520 	for (i = sh->disks; i--; ) {
521 		struct r5dev *dev = &sh->dev[i];
522 
523 		if (dev->toread || dev->read || dev->towrite || dev->written ||
524 		    test_bit(R5_LOCKED, &dev->flags)) {
525 			pr_err("sector=%llx i=%d %p %p %p %p %d\n",
526 			       (unsigned long long)sh->sector, i, dev->toread,
527 			       dev->read, dev->towrite, dev->written,
528 			       test_bit(R5_LOCKED, &dev->flags));
529 			WARN_ON(1);
530 		}
531 		dev->flags = 0;
532 		dev->sector = raid5_compute_blocknr(sh, i, previous);
533 	}
534 	if (read_seqcount_retry(&conf->gen_lock, seq))
535 		goto retry;
536 	sh->overwrite_disks = 0;
537 	insert_hash(conf, sh);
538 	sh->cpu = smp_processor_id();
539 	set_bit(STRIPE_BATCH_READY, &sh->state);
540 }
541 
542 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
543 					 short generation)
544 {
545 	struct stripe_head *sh;
546 
547 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
548 	hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
549 		if (sh->sector == sector && sh->generation == generation)
550 			return sh;
551 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
552 	return NULL;
553 }
554 
555 /*
556  * Need to check if array has failed when deciding whether to:
557  *  - start an array
558  *  - remove non-faulty devices
559  *  - add a spare
560  *  - allow a reshape
561  * This determination is simple when no reshape is happening.
562  * However if there is a reshape, we need to carefully check
563  * both the before and after sections.
564  * This is because some failed devices may only affect one
565  * of the two sections, and some non-in_sync devices may
566  * be insync in the section most affected by failed devices.
567  */
568 int raid5_calc_degraded(struct r5conf *conf)
569 {
570 	int degraded, degraded2;
571 	int i;
572 
573 	rcu_read_lock();
574 	degraded = 0;
575 	for (i = 0; i < conf->previous_raid_disks; i++) {
576 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
577 		if (rdev && test_bit(Faulty, &rdev->flags))
578 			rdev = rcu_dereference(conf->disks[i].replacement);
579 		if (!rdev || test_bit(Faulty, &rdev->flags))
580 			degraded++;
581 		else if (test_bit(In_sync, &rdev->flags))
582 			;
583 		else
584 			/* not in-sync or faulty.
585 			 * If the reshape increases the number of devices,
586 			 * this is being recovered by the reshape, so
587 			 * this 'previous' section is not in_sync.
588 			 * If the number of devices is being reduced however,
589 			 * the device can only be part of the array if
590 			 * we are reverting a reshape, so this section will
591 			 * be in-sync.
592 			 */
593 			if (conf->raid_disks >= conf->previous_raid_disks)
594 				degraded++;
595 	}
596 	rcu_read_unlock();
597 	if (conf->raid_disks == conf->previous_raid_disks)
598 		return degraded;
599 	rcu_read_lock();
600 	degraded2 = 0;
601 	for (i = 0; i < conf->raid_disks; i++) {
602 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
603 		if (rdev && test_bit(Faulty, &rdev->flags))
604 			rdev = rcu_dereference(conf->disks[i].replacement);
605 		if (!rdev || test_bit(Faulty, &rdev->flags))
606 			degraded2++;
607 		else if (test_bit(In_sync, &rdev->flags))
608 			;
609 		else
610 			/* not in-sync or faulty.
611 			 * If reshape increases the number of devices, this
612 			 * section has already been recovered, else it
613 			 * almost certainly hasn't.
614 			 */
615 			if (conf->raid_disks <= conf->previous_raid_disks)
616 				degraded2++;
617 	}
618 	rcu_read_unlock();
619 	if (degraded2 > degraded)
620 		return degraded2;
621 	return degraded;
622 }
623 
624 static int has_failed(struct r5conf *conf)
625 {
626 	int degraded;
627 
628 	if (conf->mddev->reshape_position == MaxSector)
629 		return conf->mddev->degraded > conf->max_degraded;
630 
631 	degraded = raid5_calc_degraded(conf);
632 	if (degraded > conf->max_degraded)
633 		return 1;
634 	return 0;
635 }
636 
637 struct stripe_head *
638 raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
639 			int previous, int noblock, int noquiesce)
640 {
641 	struct stripe_head *sh;
642 	int hash = stripe_hash_locks_hash(sector);
643 	int inc_empty_inactive_list_flag;
644 
645 	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
646 
647 	spin_lock_irq(conf->hash_locks + hash);
648 
649 	do {
650 		wait_event_lock_irq(conf->wait_for_quiescent,
651 				    conf->quiesce == 0 || noquiesce,
652 				    *(conf->hash_locks + hash));
653 		sh = __find_stripe(conf, sector, conf->generation - previous);
654 		if (!sh) {
655 			if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
656 				sh = get_free_stripe(conf, hash);
657 				if (!sh && !test_bit(R5_DID_ALLOC,
658 						     &conf->cache_state))
659 					set_bit(R5_ALLOC_MORE,
660 						&conf->cache_state);
661 			}
662 			if (noblock && sh == NULL)
663 				break;
664 
665 			r5c_check_stripe_cache_usage(conf);
666 			if (!sh) {
667 				set_bit(R5_INACTIVE_BLOCKED,
668 					&conf->cache_state);
669 				r5l_wake_reclaim(conf->log, 0);
670 				wait_event_lock_irq(
671 					conf->wait_for_stripe,
672 					!list_empty(conf->inactive_list + hash) &&
673 					(atomic_read(&conf->active_stripes)
674 					 < (conf->max_nr_stripes * 3 / 4)
675 					 || !test_bit(R5_INACTIVE_BLOCKED,
676 						      &conf->cache_state)),
677 					*(conf->hash_locks + hash));
678 				clear_bit(R5_INACTIVE_BLOCKED,
679 					  &conf->cache_state);
680 			} else {
681 				init_stripe(sh, sector, previous);
682 				atomic_inc(&sh->count);
683 			}
684 		} else if (!atomic_inc_not_zero(&sh->count)) {
685 			spin_lock(&conf->device_lock);
686 			if (!atomic_read(&sh->count)) {
687 				if (!test_bit(STRIPE_HANDLE, &sh->state))
688 					atomic_inc(&conf->active_stripes);
689 				BUG_ON(list_empty(&sh->lru) &&
690 				       !test_bit(STRIPE_EXPANDING, &sh->state));
691 				inc_empty_inactive_list_flag = 0;
692 				if (!list_empty(conf->inactive_list + hash))
693 					inc_empty_inactive_list_flag = 1;
694 				list_del_init(&sh->lru);
695 				if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
696 					atomic_inc(&conf->empty_inactive_list_nr);
697 				if (sh->group) {
698 					sh->group->stripes_cnt--;
699 					sh->group = NULL;
700 				}
701 			}
702 			atomic_inc(&sh->count);
703 			spin_unlock(&conf->device_lock);
704 		}
705 	} while (sh == NULL);
706 
707 	spin_unlock_irq(conf->hash_locks + hash);
708 	return sh;
709 }
710 
711 static bool is_full_stripe_write(struct stripe_head *sh)
712 {
713 	BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
714 	return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
715 }
716 
717 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
718 {
719 	if (sh1 > sh2) {
720 		spin_lock_irq(&sh2->stripe_lock);
721 		spin_lock_nested(&sh1->stripe_lock, 1);
722 	} else {
723 		spin_lock_irq(&sh1->stripe_lock);
724 		spin_lock_nested(&sh2->stripe_lock, 1);
725 	}
726 }
727 
728 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
729 {
730 	spin_unlock(&sh1->stripe_lock);
731 	spin_unlock_irq(&sh2->stripe_lock);
732 }
733 
734 /* Only freshly new full stripe normal write stripe can be added to a batch list */
735 static bool stripe_can_batch(struct stripe_head *sh)
736 {
737 	struct r5conf *conf = sh->raid_conf;
738 
739 	if (conf->log || raid5_has_ppl(conf))
740 		return false;
741 	return test_bit(STRIPE_BATCH_READY, &sh->state) &&
742 		!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
743 		is_full_stripe_write(sh);
744 }
745 
746 /* we only do back search */
747 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
748 {
749 	struct stripe_head *head;
750 	sector_t head_sector, tmp_sec;
751 	int hash;
752 	int dd_idx;
753 	int inc_empty_inactive_list_flag;
754 
755 	/* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
756 	tmp_sec = sh->sector;
757 	if (!sector_div(tmp_sec, conf->chunk_sectors))
758 		return;
759 	head_sector = sh->sector - STRIPE_SECTORS;
760 
761 	hash = stripe_hash_locks_hash(head_sector);
762 	spin_lock_irq(conf->hash_locks + hash);
763 	head = __find_stripe(conf, head_sector, conf->generation);
764 	if (head && !atomic_inc_not_zero(&head->count)) {
765 		spin_lock(&conf->device_lock);
766 		if (!atomic_read(&head->count)) {
767 			if (!test_bit(STRIPE_HANDLE, &head->state))
768 				atomic_inc(&conf->active_stripes);
769 			BUG_ON(list_empty(&head->lru) &&
770 			       !test_bit(STRIPE_EXPANDING, &head->state));
771 			inc_empty_inactive_list_flag = 0;
772 			if (!list_empty(conf->inactive_list + hash))
773 				inc_empty_inactive_list_flag = 1;
774 			list_del_init(&head->lru);
775 			if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
776 				atomic_inc(&conf->empty_inactive_list_nr);
777 			if (head->group) {
778 				head->group->stripes_cnt--;
779 				head->group = NULL;
780 			}
781 		}
782 		atomic_inc(&head->count);
783 		spin_unlock(&conf->device_lock);
784 	}
785 	spin_unlock_irq(conf->hash_locks + hash);
786 
787 	if (!head)
788 		return;
789 	if (!stripe_can_batch(head))
790 		goto out;
791 
792 	lock_two_stripes(head, sh);
793 	/* clear_batch_ready clear the flag */
794 	if (!stripe_can_batch(head) || !stripe_can_batch(sh))
795 		goto unlock_out;
796 
797 	if (sh->batch_head)
798 		goto unlock_out;
799 
800 	dd_idx = 0;
801 	while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
802 		dd_idx++;
803 	if (head->dev[dd_idx].towrite->bi_opf != sh->dev[dd_idx].towrite->bi_opf ||
804 	    bio_op(head->dev[dd_idx].towrite) != bio_op(sh->dev[dd_idx].towrite))
805 		goto unlock_out;
806 
807 	if (head->batch_head) {
808 		spin_lock(&head->batch_head->batch_lock);
809 		/* This batch list is already running */
810 		if (!stripe_can_batch(head)) {
811 			spin_unlock(&head->batch_head->batch_lock);
812 			goto unlock_out;
813 		}
814 		/*
815 		 * We must assign batch_head of this stripe within the
816 		 * batch_lock, otherwise clear_batch_ready of batch head
817 		 * stripe could clear BATCH_READY bit of this stripe and
818 		 * this stripe->batch_head doesn't get assigned, which
819 		 * could confuse clear_batch_ready for this stripe
820 		 */
821 		sh->batch_head = head->batch_head;
822 
823 		/*
824 		 * at this point, head's BATCH_READY could be cleared, but we
825 		 * can still add the stripe to batch list
826 		 */
827 		list_add(&sh->batch_list, &head->batch_list);
828 		spin_unlock(&head->batch_head->batch_lock);
829 	} else {
830 		head->batch_head = head;
831 		sh->batch_head = head->batch_head;
832 		spin_lock(&head->batch_lock);
833 		list_add_tail(&sh->batch_list, &head->batch_list);
834 		spin_unlock(&head->batch_lock);
835 	}
836 
837 	if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
838 		if (atomic_dec_return(&conf->preread_active_stripes)
839 		    < IO_THRESHOLD)
840 			md_wakeup_thread(conf->mddev->thread);
841 
842 	if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
843 		int seq = sh->bm_seq;
844 		if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
845 		    sh->batch_head->bm_seq > seq)
846 			seq = sh->batch_head->bm_seq;
847 		set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
848 		sh->batch_head->bm_seq = seq;
849 	}
850 
851 	atomic_inc(&sh->count);
852 unlock_out:
853 	unlock_two_stripes(head, sh);
854 out:
855 	raid5_release_stripe(head);
856 }
857 
858 /* Determine if 'data_offset' or 'new_data_offset' should be used
859  * in this stripe_head.
860  */
861 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
862 {
863 	sector_t progress = conf->reshape_progress;
864 	/* Need a memory barrier to make sure we see the value
865 	 * of conf->generation, or ->data_offset that was set before
866 	 * reshape_progress was updated.
867 	 */
868 	smp_rmb();
869 	if (progress == MaxSector)
870 		return 0;
871 	if (sh->generation == conf->generation - 1)
872 		return 0;
873 	/* We are in a reshape, and this is a new-generation stripe,
874 	 * so use new_data_offset.
875 	 */
876 	return 1;
877 }
878 
879 static void dispatch_bio_list(struct bio_list *tmp)
880 {
881 	struct bio *bio;
882 
883 	while ((bio = bio_list_pop(tmp)))
884 		generic_make_request(bio);
885 }
886 
887 static int cmp_stripe(void *priv, struct list_head *a, struct list_head *b)
888 {
889 	const struct r5pending_data *da = list_entry(a,
890 				struct r5pending_data, sibling);
891 	const struct r5pending_data *db = list_entry(b,
892 				struct r5pending_data, sibling);
893 	if (da->sector > db->sector)
894 		return 1;
895 	if (da->sector < db->sector)
896 		return -1;
897 	return 0;
898 }
899 
900 static void dispatch_defer_bios(struct r5conf *conf, int target,
901 				struct bio_list *list)
902 {
903 	struct r5pending_data *data;
904 	struct list_head *first, *next = NULL;
905 	int cnt = 0;
906 
907 	if (conf->pending_data_cnt == 0)
908 		return;
909 
910 	list_sort(NULL, &conf->pending_list, cmp_stripe);
911 
912 	first = conf->pending_list.next;
913 
914 	/* temporarily move the head */
915 	if (conf->next_pending_data)
916 		list_move_tail(&conf->pending_list,
917 				&conf->next_pending_data->sibling);
918 
919 	while (!list_empty(&conf->pending_list)) {
920 		data = list_first_entry(&conf->pending_list,
921 			struct r5pending_data, sibling);
922 		if (&data->sibling == first)
923 			first = data->sibling.next;
924 		next = data->sibling.next;
925 
926 		bio_list_merge(list, &data->bios);
927 		list_move(&data->sibling, &conf->free_list);
928 		cnt++;
929 		if (cnt >= target)
930 			break;
931 	}
932 	conf->pending_data_cnt -= cnt;
933 	BUG_ON(conf->pending_data_cnt < 0 || cnt < target);
934 
935 	if (next != &conf->pending_list)
936 		conf->next_pending_data = list_entry(next,
937 				struct r5pending_data, sibling);
938 	else
939 		conf->next_pending_data = NULL;
940 	/* list isn't empty */
941 	if (first != &conf->pending_list)
942 		list_move_tail(&conf->pending_list, first);
943 }
944 
945 static void flush_deferred_bios(struct r5conf *conf)
946 {
947 	struct bio_list tmp = BIO_EMPTY_LIST;
948 
949 	if (conf->pending_data_cnt == 0)
950 		return;
951 
952 	spin_lock(&conf->pending_bios_lock);
953 	dispatch_defer_bios(conf, conf->pending_data_cnt, &tmp);
954 	BUG_ON(conf->pending_data_cnt != 0);
955 	spin_unlock(&conf->pending_bios_lock);
956 
957 	dispatch_bio_list(&tmp);
958 }
959 
960 static void defer_issue_bios(struct r5conf *conf, sector_t sector,
961 				struct bio_list *bios)
962 {
963 	struct bio_list tmp = BIO_EMPTY_LIST;
964 	struct r5pending_data *ent;
965 
966 	spin_lock(&conf->pending_bios_lock);
967 	ent = list_first_entry(&conf->free_list, struct r5pending_data,
968 							sibling);
969 	list_move_tail(&ent->sibling, &conf->pending_list);
970 	ent->sector = sector;
971 	bio_list_init(&ent->bios);
972 	bio_list_merge(&ent->bios, bios);
973 	conf->pending_data_cnt++;
974 	if (conf->pending_data_cnt >= PENDING_IO_MAX)
975 		dispatch_defer_bios(conf, PENDING_IO_ONE_FLUSH, &tmp);
976 
977 	spin_unlock(&conf->pending_bios_lock);
978 
979 	dispatch_bio_list(&tmp);
980 }
981 
982 static void
983 raid5_end_read_request(struct bio *bi);
984 static void
985 raid5_end_write_request(struct bio *bi);
986 
987 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
988 {
989 	struct r5conf *conf = sh->raid_conf;
990 	int i, disks = sh->disks;
991 	struct stripe_head *head_sh = sh;
992 	struct bio_list pending_bios = BIO_EMPTY_LIST;
993 	bool should_defer;
994 
995 	might_sleep();
996 
997 	if (log_stripe(sh, s) == 0)
998 		return;
999 
1000 	should_defer = conf->batch_bio_dispatch && conf->group_cnt;
1001 
1002 	for (i = disks; i--; ) {
1003 		int op, op_flags = 0;
1004 		int replace_only = 0;
1005 		struct bio *bi, *rbi;
1006 		struct md_rdev *rdev, *rrdev = NULL;
1007 
1008 		sh = head_sh;
1009 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
1010 			op = REQ_OP_WRITE;
1011 			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
1012 				op_flags = REQ_FUA;
1013 			if (test_bit(R5_Discard, &sh->dev[i].flags))
1014 				op = REQ_OP_DISCARD;
1015 		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1016 			op = REQ_OP_READ;
1017 		else if (test_and_clear_bit(R5_WantReplace,
1018 					    &sh->dev[i].flags)) {
1019 			op = REQ_OP_WRITE;
1020 			replace_only = 1;
1021 		} else
1022 			continue;
1023 		if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
1024 			op_flags |= REQ_SYNC;
1025 
1026 again:
1027 		bi = &sh->dev[i].req;
1028 		rbi = &sh->dev[i].rreq; /* For writing to replacement */
1029 
1030 		rcu_read_lock();
1031 		rrdev = rcu_dereference(conf->disks[i].replacement);
1032 		smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
1033 		rdev = rcu_dereference(conf->disks[i].rdev);
1034 		if (!rdev) {
1035 			rdev = rrdev;
1036 			rrdev = NULL;
1037 		}
1038 		if (op_is_write(op)) {
1039 			if (replace_only)
1040 				rdev = NULL;
1041 			if (rdev == rrdev)
1042 				/* We raced and saw duplicates */
1043 				rrdev = NULL;
1044 		} else {
1045 			if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
1046 				rdev = rrdev;
1047 			rrdev = NULL;
1048 		}
1049 
1050 		if (rdev && test_bit(Faulty, &rdev->flags))
1051 			rdev = NULL;
1052 		if (rdev)
1053 			atomic_inc(&rdev->nr_pending);
1054 		if (rrdev && test_bit(Faulty, &rrdev->flags))
1055 			rrdev = NULL;
1056 		if (rrdev)
1057 			atomic_inc(&rrdev->nr_pending);
1058 		rcu_read_unlock();
1059 
1060 		/* We have already checked bad blocks for reads.  Now
1061 		 * need to check for writes.  We never accept write errors
1062 		 * on the replacement, so we don't to check rrdev.
1063 		 */
1064 		while (op_is_write(op) && rdev &&
1065 		       test_bit(WriteErrorSeen, &rdev->flags)) {
1066 			sector_t first_bad;
1067 			int bad_sectors;
1068 			int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
1069 					      &first_bad, &bad_sectors);
1070 			if (!bad)
1071 				break;
1072 
1073 			if (bad < 0) {
1074 				set_bit(BlockedBadBlocks, &rdev->flags);
1075 				if (!conf->mddev->external &&
1076 				    conf->mddev->sb_flags) {
1077 					/* It is very unlikely, but we might
1078 					 * still need to write out the
1079 					 * bad block log - better give it
1080 					 * a chance*/
1081 					md_check_recovery(conf->mddev);
1082 				}
1083 				/*
1084 				 * Because md_wait_for_blocked_rdev
1085 				 * will dec nr_pending, we must
1086 				 * increment it first.
1087 				 */
1088 				atomic_inc(&rdev->nr_pending);
1089 				md_wait_for_blocked_rdev(rdev, conf->mddev);
1090 			} else {
1091 				/* Acknowledged bad block - skip the write */
1092 				rdev_dec_pending(rdev, conf->mddev);
1093 				rdev = NULL;
1094 			}
1095 		}
1096 
1097 		if (rdev) {
1098 			if (s->syncing || s->expanding || s->expanded
1099 			    || s->replacing)
1100 				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1101 
1102 			set_bit(STRIPE_IO_STARTED, &sh->state);
1103 
1104 			bio_set_dev(bi, rdev->bdev);
1105 			bio_set_op_attrs(bi, op, op_flags);
1106 			bi->bi_end_io = op_is_write(op)
1107 				? raid5_end_write_request
1108 				: raid5_end_read_request;
1109 			bi->bi_private = sh;
1110 
1111 			pr_debug("%s: for %llu schedule op %d on disc %d\n",
1112 				__func__, (unsigned long long)sh->sector,
1113 				bi->bi_opf, i);
1114 			atomic_inc(&sh->count);
1115 			if (sh != head_sh)
1116 				atomic_inc(&head_sh->count);
1117 			if (use_new_offset(conf, sh))
1118 				bi->bi_iter.bi_sector = (sh->sector
1119 						 + rdev->new_data_offset);
1120 			else
1121 				bi->bi_iter.bi_sector = (sh->sector
1122 						 + rdev->data_offset);
1123 			if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1124 				bi->bi_opf |= REQ_NOMERGE;
1125 
1126 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1127 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1128 
1129 			if (!op_is_write(op) &&
1130 			    test_bit(R5_InJournal, &sh->dev[i].flags))
1131 				/*
1132 				 * issuing read for a page in journal, this
1133 				 * must be preparing for prexor in rmw; read
1134 				 * the data into orig_page
1135 				 */
1136 				sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
1137 			else
1138 				sh->dev[i].vec.bv_page = sh->dev[i].page;
1139 			bi->bi_vcnt = 1;
1140 			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1141 			bi->bi_io_vec[0].bv_offset = 0;
1142 			bi->bi_iter.bi_size = STRIPE_SIZE;
1143 			/*
1144 			 * If this is discard request, set bi_vcnt 0. We don't
1145 			 * want to confuse SCSI because SCSI will replace payload
1146 			 */
1147 			if (op == REQ_OP_DISCARD)
1148 				bi->bi_vcnt = 0;
1149 			if (rrdev)
1150 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1151 
1152 			if (conf->mddev->gendisk)
1153 				trace_block_bio_remap(bi->bi_disk->queue,
1154 						      bi, disk_devt(conf->mddev->gendisk),
1155 						      sh->dev[i].sector);
1156 			if (should_defer && op_is_write(op))
1157 				bio_list_add(&pending_bios, bi);
1158 			else
1159 				generic_make_request(bi);
1160 		}
1161 		if (rrdev) {
1162 			if (s->syncing || s->expanding || s->expanded
1163 			    || s->replacing)
1164 				md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1165 
1166 			set_bit(STRIPE_IO_STARTED, &sh->state);
1167 
1168 			bio_set_dev(rbi, rrdev->bdev);
1169 			bio_set_op_attrs(rbi, op, op_flags);
1170 			BUG_ON(!op_is_write(op));
1171 			rbi->bi_end_io = raid5_end_write_request;
1172 			rbi->bi_private = sh;
1173 
1174 			pr_debug("%s: for %llu schedule op %d on "
1175 				 "replacement disc %d\n",
1176 				__func__, (unsigned long long)sh->sector,
1177 				rbi->bi_opf, i);
1178 			atomic_inc(&sh->count);
1179 			if (sh != head_sh)
1180 				atomic_inc(&head_sh->count);
1181 			if (use_new_offset(conf, sh))
1182 				rbi->bi_iter.bi_sector = (sh->sector
1183 						  + rrdev->new_data_offset);
1184 			else
1185 				rbi->bi_iter.bi_sector = (sh->sector
1186 						  + rrdev->data_offset);
1187 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1188 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1189 			sh->dev[i].rvec.bv_page = sh->dev[i].page;
1190 			rbi->bi_vcnt = 1;
1191 			rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1192 			rbi->bi_io_vec[0].bv_offset = 0;
1193 			rbi->bi_iter.bi_size = STRIPE_SIZE;
1194 			/*
1195 			 * If this is discard request, set bi_vcnt 0. We don't
1196 			 * want to confuse SCSI because SCSI will replace payload
1197 			 */
1198 			if (op == REQ_OP_DISCARD)
1199 				rbi->bi_vcnt = 0;
1200 			if (conf->mddev->gendisk)
1201 				trace_block_bio_remap(rbi->bi_disk->queue,
1202 						      rbi, disk_devt(conf->mddev->gendisk),
1203 						      sh->dev[i].sector);
1204 			if (should_defer && op_is_write(op))
1205 				bio_list_add(&pending_bios, rbi);
1206 			else
1207 				generic_make_request(rbi);
1208 		}
1209 		if (!rdev && !rrdev) {
1210 			if (op_is_write(op))
1211 				set_bit(STRIPE_DEGRADED, &sh->state);
1212 			pr_debug("skip op %d on disc %d for sector %llu\n",
1213 				bi->bi_opf, i, (unsigned long long)sh->sector);
1214 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
1215 			set_bit(STRIPE_HANDLE, &sh->state);
1216 		}
1217 
1218 		if (!head_sh->batch_head)
1219 			continue;
1220 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1221 				      batch_list);
1222 		if (sh != head_sh)
1223 			goto again;
1224 	}
1225 
1226 	if (should_defer && !bio_list_empty(&pending_bios))
1227 		defer_issue_bios(conf, head_sh->sector, &pending_bios);
1228 }
1229 
1230 static struct dma_async_tx_descriptor *
1231 async_copy_data(int frombio, struct bio *bio, struct page **page,
1232 	sector_t sector, struct dma_async_tx_descriptor *tx,
1233 	struct stripe_head *sh, int no_skipcopy)
1234 {
1235 	struct bio_vec bvl;
1236 	struct bvec_iter iter;
1237 	struct page *bio_page;
1238 	int page_offset;
1239 	struct async_submit_ctl submit;
1240 	enum async_tx_flags flags = 0;
1241 
1242 	if (bio->bi_iter.bi_sector >= sector)
1243 		page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1244 	else
1245 		page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1246 
1247 	if (frombio)
1248 		flags |= ASYNC_TX_FENCE;
1249 	init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1250 
1251 	bio_for_each_segment(bvl, bio, iter) {
1252 		int len = bvl.bv_len;
1253 		int clen;
1254 		int b_offset = 0;
1255 
1256 		if (page_offset < 0) {
1257 			b_offset = -page_offset;
1258 			page_offset += b_offset;
1259 			len -= b_offset;
1260 		}
1261 
1262 		if (len > 0 && page_offset + len > STRIPE_SIZE)
1263 			clen = STRIPE_SIZE - page_offset;
1264 		else
1265 			clen = len;
1266 
1267 		if (clen > 0) {
1268 			b_offset += bvl.bv_offset;
1269 			bio_page = bvl.bv_page;
1270 			if (frombio) {
1271 				if (sh->raid_conf->skip_copy &&
1272 				    b_offset == 0 && page_offset == 0 &&
1273 				    clen == STRIPE_SIZE &&
1274 				    !no_skipcopy)
1275 					*page = bio_page;
1276 				else
1277 					tx = async_memcpy(*page, bio_page, page_offset,
1278 						  b_offset, clen, &submit);
1279 			} else
1280 				tx = async_memcpy(bio_page, *page, b_offset,
1281 						  page_offset, clen, &submit);
1282 		}
1283 		/* chain the operations */
1284 		submit.depend_tx = tx;
1285 
1286 		if (clen < len) /* hit end of page */
1287 			break;
1288 		page_offset +=  len;
1289 	}
1290 
1291 	return tx;
1292 }
1293 
1294 static void ops_complete_biofill(void *stripe_head_ref)
1295 {
1296 	struct stripe_head *sh = stripe_head_ref;
1297 	int i;
1298 
1299 	pr_debug("%s: stripe %llu\n", __func__,
1300 		(unsigned long long)sh->sector);
1301 
1302 	/* clear completed biofills */
1303 	for (i = sh->disks; i--; ) {
1304 		struct r5dev *dev = &sh->dev[i];
1305 
1306 		/* acknowledge completion of a biofill operation */
1307 		/* and check if we need to reply to a read request,
1308 		 * new R5_Wantfill requests are held off until
1309 		 * !STRIPE_BIOFILL_RUN
1310 		 */
1311 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1312 			struct bio *rbi, *rbi2;
1313 
1314 			BUG_ON(!dev->read);
1315 			rbi = dev->read;
1316 			dev->read = NULL;
1317 			while (rbi && rbi->bi_iter.bi_sector <
1318 				dev->sector + STRIPE_SECTORS) {
1319 				rbi2 = r5_next_bio(rbi, dev->sector);
1320 				bio_endio(rbi);
1321 				rbi = rbi2;
1322 			}
1323 		}
1324 	}
1325 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1326 
1327 	set_bit(STRIPE_HANDLE, &sh->state);
1328 	raid5_release_stripe(sh);
1329 }
1330 
1331 static void ops_run_biofill(struct stripe_head *sh)
1332 {
1333 	struct dma_async_tx_descriptor *tx = NULL;
1334 	struct async_submit_ctl submit;
1335 	int i;
1336 
1337 	BUG_ON(sh->batch_head);
1338 	pr_debug("%s: stripe %llu\n", __func__,
1339 		(unsigned long long)sh->sector);
1340 
1341 	for (i = sh->disks; i--; ) {
1342 		struct r5dev *dev = &sh->dev[i];
1343 		if (test_bit(R5_Wantfill, &dev->flags)) {
1344 			struct bio *rbi;
1345 			spin_lock_irq(&sh->stripe_lock);
1346 			dev->read = rbi = dev->toread;
1347 			dev->toread = NULL;
1348 			spin_unlock_irq(&sh->stripe_lock);
1349 			while (rbi && rbi->bi_iter.bi_sector <
1350 				dev->sector + STRIPE_SECTORS) {
1351 				tx = async_copy_data(0, rbi, &dev->page,
1352 						     dev->sector, tx, sh, 0);
1353 				rbi = r5_next_bio(rbi, dev->sector);
1354 			}
1355 		}
1356 	}
1357 
1358 	atomic_inc(&sh->count);
1359 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1360 	async_trigger_callback(&submit);
1361 }
1362 
1363 static void mark_target_uptodate(struct stripe_head *sh, int target)
1364 {
1365 	struct r5dev *tgt;
1366 
1367 	if (target < 0)
1368 		return;
1369 
1370 	tgt = &sh->dev[target];
1371 	set_bit(R5_UPTODATE, &tgt->flags);
1372 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1373 	clear_bit(R5_Wantcompute, &tgt->flags);
1374 }
1375 
1376 static void ops_complete_compute(void *stripe_head_ref)
1377 {
1378 	struct stripe_head *sh = stripe_head_ref;
1379 
1380 	pr_debug("%s: stripe %llu\n", __func__,
1381 		(unsigned long long)sh->sector);
1382 
1383 	/* mark the computed target(s) as uptodate */
1384 	mark_target_uptodate(sh, sh->ops.target);
1385 	mark_target_uptodate(sh, sh->ops.target2);
1386 
1387 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1388 	if (sh->check_state == check_state_compute_run)
1389 		sh->check_state = check_state_compute_result;
1390 	set_bit(STRIPE_HANDLE, &sh->state);
1391 	raid5_release_stripe(sh);
1392 }
1393 
1394 /* return a pointer to the address conversion region of the scribble buffer */
1395 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1396 				 struct raid5_percpu *percpu, int i)
1397 {
1398 	void *addr;
1399 
1400 	addr = flex_array_get(percpu->scribble, i);
1401 	return addr + sizeof(struct page *) * (sh->disks + 2);
1402 }
1403 
1404 /* return a pointer to the address conversion region of the scribble buffer */
1405 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1406 {
1407 	void *addr;
1408 
1409 	addr = flex_array_get(percpu->scribble, i);
1410 	return addr;
1411 }
1412 
1413 static struct dma_async_tx_descriptor *
1414 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1415 {
1416 	int disks = sh->disks;
1417 	struct page **xor_srcs = to_addr_page(percpu, 0);
1418 	int target = sh->ops.target;
1419 	struct r5dev *tgt = &sh->dev[target];
1420 	struct page *xor_dest = tgt->page;
1421 	int count = 0;
1422 	struct dma_async_tx_descriptor *tx;
1423 	struct async_submit_ctl submit;
1424 	int i;
1425 
1426 	BUG_ON(sh->batch_head);
1427 
1428 	pr_debug("%s: stripe %llu block: %d\n",
1429 		__func__, (unsigned long long)sh->sector, target);
1430 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1431 
1432 	for (i = disks; i--; )
1433 		if (i != target)
1434 			xor_srcs[count++] = sh->dev[i].page;
1435 
1436 	atomic_inc(&sh->count);
1437 
1438 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1439 			  ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1440 	if (unlikely(count == 1))
1441 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1442 	else
1443 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1444 
1445 	return tx;
1446 }
1447 
1448 /* set_syndrome_sources - populate source buffers for gen_syndrome
1449  * @srcs - (struct page *) array of size sh->disks
1450  * @sh - stripe_head to parse
1451  *
1452  * Populates srcs in proper layout order for the stripe and returns the
1453  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1454  * destination buffer is recorded in srcs[count] and the Q destination
1455  * is recorded in srcs[count+1]].
1456  */
1457 static int set_syndrome_sources(struct page **srcs,
1458 				struct stripe_head *sh,
1459 				int srctype)
1460 {
1461 	int disks = sh->disks;
1462 	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1463 	int d0_idx = raid6_d0(sh);
1464 	int count;
1465 	int i;
1466 
1467 	for (i = 0; i < disks; i++)
1468 		srcs[i] = NULL;
1469 
1470 	count = 0;
1471 	i = d0_idx;
1472 	do {
1473 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1474 		struct r5dev *dev = &sh->dev[i];
1475 
1476 		if (i == sh->qd_idx || i == sh->pd_idx ||
1477 		    (srctype == SYNDROME_SRC_ALL) ||
1478 		    (srctype == SYNDROME_SRC_WANT_DRAIN &&
1479 		     (test_bit(R5_Wantdrain, &dev->flags) ||
1480 		      test_bit(R5_InJournal, &dev->flags))) ||
1481 		    (srctype == SYNDROME_SRC_WRITTEN &&
1482 		     (dev->written ||
1483 		      test_bit(R5_InJournal, &dev->flags)))) {
1484 			if (test_bit(R5_InJournal, &dev->flags))
1485 				srcs[slot] = sh->dev[i].orig_page;
1486 			else
1487 				srcs[slot] = sh->dev[i].page;
1488 		}
1489 		i = raid6_next_disk(i, disks);
1490 	} while (i != d0_idx);
1491 
1492 	return syndrome_disks;
1493 }
1494 
1495 static struct dma_async_tx_descriptor *
1496 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1497 {
1498 	int disks = sh->disks;
1499 	struct page **blocks = to_addr_page(percpu, 0);
1500 	int target;
1501 	int qd_idx = sh->qd_idx;
1502 	struct dma_async_tx_descriptor *tx;
1503 	struct async_submit_ctl submit;
1504 	struct r5dev *tgt;
1505 	struct page *dest;
1506 	int i;
1507 	int count;
1508 
1509 	BUG_ON(sh->batch_head);
1510 	if (sh->ops.target < 0)
1511 		target = sh->ops.target2;
1512 	else if (sh->ops.target2 < 0)
1513 		target = sh->ops.target;
1514 	else
1515 		/* we should only have one valid target */
1516 		BUG();
1517 	BUG_ON(target < 0);
1518 	pr_debug("%s: stripe %llu block: %d\n",
1519 		__func__, (unsigned long long)sh->sector, target);
1520 
1521 	tgt = &sh->dev[target];
1522 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1523 	dest = tgt->page;
1524 
1525 	atomic_inc(&sh->count);
1526 
1527 	if (target == qd_idx) {
1528 		count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1529 		blocks[count] = NULL; /* regenerating p is not necessary */
1530 		BUG_ON(blocks[count+1] != dest); /* q should already be set */
1531 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1532 				  ops_complete_compute, sh,
1533 				  to_addr_conv(sh, percpu, 0));
1534 		tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1535 	} else {
1536 		/* Compute any data- or p-drive using XOR */
1537 		count = 0;
1538 		for (i = disks; i-- ; ) {
1539 			if (i == target || i == qd_idx)
1540 				continue;
1541 			blocks[count++] = sh->dev[i].page;
1542 		}
1543 
1544 		init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1545 				  NULL, ops_complete_compute, sh,
1546 				  to_addr_conv(sh, percpu, 0));
1547 		tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1548 	}
1549 
1550 	return tx;
1551 }
1552 
1553 static struct dma_async_tx_descriptor *
1554 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1555 {
1556 	int i, count, disks = sh->disks;
1557 	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1558 	int d0_idx = raid6_d0(sh);
1559 	int faila = -1, failb = -1;
1560 	int target = sh->ops.target;
1561 	int target2 = sh->ops.target2;
1562 	struct r5dev *tgt = &sh->dev[target];
1563 	struct r5dev *tgt2 = &sh->dev[target2];
1564 	struct dma_async_tx_descriptor *tx;
1565 	struct page **blocks = to_addr_page(percpu, 0);
1566 	struct async_submit_ctl submit;
1567 
1568 	BUG_ON(sh->batch_head);
1569 	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1570 		 __func__, (unsigned long long)sh->sector, target, target2);
1571 	BUG_ON(target < 0 || target2 < 0);
1572 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1573 	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1574 
1575 	/* we need to open-code set_syndrome_sources to handle the
1576 	 * slot number conversion for 'faila' and 'failb'
1577 	 */
1578 	for (i = 0; i < disks ; i++)
1579 		blocks[i] = NULL;
1580 	count = 0;
1581 	i = d0_idx;
1582 	do {
1583 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1584 
1585 		blocks[slot] = sh->dev[i].page;
1586 
1587 		if (i == target)
1588 			faila = slot;
1589 		if (i == target2)
1590 			failb = slot;
1591 		i = raid6_next_disk(i, disks);
1592 	} while (i != d0_idx);
1593 
1594 	BUG_ON(faila == failb);
1595 	if (failb < faila)
1596 		swap(faila, failb);
1597 	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1598 		 __func__, (unsigned long long)sh->sector, faila, failb);
1599 
1600 	atomic_inc(&sh->count);
1601 
1602 	if (failb == syndrome_disks+1) {
1603 		/* Q disk is one of the missing disks */
1604 		if (faila == syndrome_disks) {
1605 			/* Missing P+Q, just recompute */
1606 			init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1607 					  ops_complete_compute, sh,
1608 					  to_addr_conv(sh, percpu, 0));
1609 			return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1610 						  STRIPE_SIZE, &submit);
1611 		} else {
1612 			struct page *dest;
1613 			int data_target;
1614 			int qd_idx = sh->qd_idx;
1615 
1616 			/* Missing D+Q: recompute D from P, then recompute Q */
1617 			if (target == qd_idx)
1618 				data_target = target2;
1619 			else
1620 				data_target = target;
1621 
1622 			count = 0;
1623 			for (i = disks; i-- ; ) {
1624 				if (i == data_target || i == qd_idx)
1625 					continue;
1626 				blocks[count++] = sh->dev[i].page;
1627 			}
1628 			dest = sh->dev[data_target].page;
1629 			init_async_submit(&submit,
1630 					  ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1631 					  NULL, NULL, NULL,
1632 					  to_addr_conv(sh, percpu, 0));
1633 			tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1634 				       &submit);
1635 
1636 			count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1637 			init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1638 					  ops_complete_compute, sh,
1639 					  to_addr_conv(sh, percpu, 0));
1640 			return async_gen_syndrome(blocks, 0, count+2,
1641 						  STRIPE_SIZE, &submit);
1642 		}
1643 	} else {
1644 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1645 				  ops_complete_compute, sh,
1646 				  to_addr_conv(sh, percpu, 0));
1647 		if (failb == syndrome_disks) {
1648 			/* We're missing D+P. */
1649 			return async_raid6_datap_recov(syndrome_disks+2,
1650 						       STRIPE_SIZE, faila,
1651 						       blocks, &submit);
1652 		} else {
1653 			/* We're missing D+D. */
1654 			return async_raid6_2data_recov(syndrome_disks+2,
1655 						       STRIPE_SIZE, faila, failb,
1656 						       blocks, &submit);
1657 		}
1658 	}
1659 }
1660 
1661 static void ops_complete_prexor(void *stripe_head_ref)
1662 {
1663 	struct stripe_head *sh = stripe_head_ref;
1664 
1665 	pr_debug("%s: stripe %llu\n", __func__,
1666 		(unsigned long long)sh->sector);
1667 
1668 	if (r5c_is_writeback(sh->raid_conf->log))
1669 		/*
1670 		 * raid5-cache write back uses orig_page during prexor.
1671 		 * After prexor, it is time to free orig_page
1672 		 */
1673 		r5c_release_extra_page(sh);
1674 }
1675 
1676 static struct dma_async_tx_descriptor *
1677 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1678 		struct dma_async_tx_descriptor *tx)
1679 {
1680 	int disks = sh->disks;
1681 	struct page **xor_srcs = to_addr_page(percpu, 0);
1682 	int count = 0, pd_idx = sh->pd_idx, i;
1683 	struct async_submit_ctl submit;
1684 
1685 	/* existing parity data subtracted */
1686 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1687 
1688 	BUG_ON(sh->batch_head);
1689 	pr_debug("%s: stripe %llu\n", __func__,
1690 		(unsigned long long)sh->sector);
1691 
1692 	for (i = disks; i--; ) {
1693 		struct r5dev *dev = &sh->dev[i];
1694 		/* Only process blocks that are known to be uptodate */
1695 		if (test_bit(R5_InJournal, &dev->flags))
1696 			xor_srcs[count++] = dev->orig_page;
1697 		else if (test_bit(R5_Wantdrain, &dev->flags))
1698 			xor_srcs[count++] = dev->page;
1699 	}
1700 
1701 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1702 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1703 	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1704 
1705 	return tx;
1706 }
1707 
1708 static struct dma_async_tx_descriptor *
1709 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1710 		struct dma_async_tx_descriptor *tx)
1711 {
1712 	struct page **blocks = to_addr_page(percpu, 0);
1713 	int count;
1714 	struct async_submit_ctl submit;
1715 
1716 	pr_debug("%s: stripe %llu\n", __func__,
1717 		(unsigned long long)sh->sector);
1718 
1719 	count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1720 
1721 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1722 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1723 	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1724 
1725 	return tx;
1726 }
1727 
1728 static struct dma_async_tx_descriptor *
1729 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1730 {
1731 	struct r5conf *conf = sh->raid_conf;
1732 	int disks = sh->disks;
1733 	int i;
1734 	struct stripe_head *head_sh = sh;
1735 
1736 	pr_debug("%s: stripe %llu\n", __func__,
1737 		(unsigned long long)sh->sector);
1738 
1739 	for (i = disks; i--; ) {
1740 		struct r5dev *dev;
1741 		struct bio *chosen;
1742 
1743 		sh = head_sh;
1744 		if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1745 			struct bio *wbi;
1746 
1747 again:
1748 			dev = &sh->dev[i];
1749 			/*
1750 			 * clear R5_InJournal, so when rewriting a page in
1751 			 * journal, it is not skipped by r5l_log_stripe()
1752 			 */
1753 			clear_bit(R5_InJournal, &dev->flags);
1754 			spin_lock_irq(&sh->stripe_lock);
1755 			chosen = dev->towrite;
1756 			dev->towrite = NULL;
1757 			sh->overwrite_disks = 0;
1758 			BUG_ON(dev->written);
1759 			wbi = dev->written = chosen;
1760 			spin_unlock_irq(&sh->stripe_lock);
1761 			WARN_ON(dev->page != dev->orig_page);
1762 
1763 			while (wbi && wbi->bi_iter.bi_sector <
1764 				dev->sector + STRIPE_SECTORS) {
1765 				if (wbi->bi_opf & REQ_FUA)
1766 					set_bit(R5_WantFUA, &dev->flags);
1767 				if (wbi->bi_opf & REQ_SYNC)
1768 					set_bit(R5_SyncIO, &dev->flags);
1769 				if (bio_op(wbi) == REQ_OP_DISCARD)
1770 					set_bit(R5_Discard, &dev->flags);
1771 				else {
1772 					tx = async_copy_data(1, wbi, &dev->page,
1773 							     dev->sector, tx, sh,
1774 							     r5c_is_writeback(conf->log));
1775 					if (dev->page != dev->orig_page &&
1776 					    !r5c_is_writeback(conf->log)) {
1777 						set_bit(R5_SkipCopy, &dev->flags);
1778 						clear_bit(R5_UPTODATE, &dev->flags);
1779 						clear_bit(R5_OVERWRITE, &dev->flags);
1780 					}
1781 				}
1782 				wbi = r5_next_bio(wbi, dev->sector);
1783 			}
1784 
1785 			if (head_sh->batch_head) {
1786 				sh = list_first_entry(&sh->batch_list,
1787 						      struct stripe_head,
1788 						      batch_list);
1789 				if (sh == head_sh)
1790 					continue;
1791 				goto again;
1792 			}
1793 		}
1794 	}
1795 
1796 	return tx;
1797 }
1798 
1799 static void ops_complete_reconstruct(void *stripe_head_ref)
1800 {
1801 	struct stripe_head *sh = stripe_head_ref;
1802 	int disks = sh->disks;
1803 	int pd_idx = sh->pd_idx;
1804 	int qd_idx = sh->qd_idx;
1805 	int i;
1806 	bool fua = false, sync = false, discard = false;
1807 
1808 	pr_debug("%s: stripe %llu\n", __func__,
1809 		(unsigned long long)sh->sector);
1810 
1811 	for (i = disks; i--; ) {
1812 		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1813 		sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1814 		discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1815 	}
1816 
1817 	for (i = disks; i--; ) {
1818 		struct r5dev *dev = &sh->dev[i];
1819 
1820 		if (dev->written || i == pd_idx || i == qd_idx) {
1821 			if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1822 				set_bit(R5_UPTODATE, &dev->flags);
1823 			if (fua)
1824 				set_bit(R5_WantFUA, &dev->flags);
1825 			if (sync)
1826 				set_bit(R5_SyncIO, &dev->flags);
1827 		}
1828 	}
1829 
1830 	if (sh->reconstruct_state == reconstruct_state_drain_run)
1831 		sh->reconstruct_state = reconstruct_state_drain_result;
1832 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1833 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1834 	else {
1835 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1836 		sh->reconstruct_state = reconstruct_state_result;
1837 	}
1838 
1839 	set_bit(STRIPE_HANDLE, &sh->state);
1840 	raid5_release_stripe(sh);
1841 }
1842 
1843 static void
1844 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1845 		     struct dma_async_tx_descriptor *tx)
1846 {
1847 	int disks = sh->disks;
1848 	struct page **xor_srcs;
1849 	struct async_submit_ctl submit;
1850 	int count, pd_idx = sh->pd_idx, i;
1851 	struct page *xor_dest;
1852 	int prexor = 0;
1853 	unsigned long flags;
1854 	int j = 0;
1855 	struct stripe_head *head_sh = sh;
1856 	int last_stripe;
1857 
1858 	pr_debug("%s: stripe %llu\n", __func__,
1859 		(unsigned long long)sh->sector);
1860 
1861 	for (i = 0; i < sh->disks; i++) {
1862 		if (pd_idx == i)
1863 			continue;
1864 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1865 			break;
1866 	}
1867 	if (i >= sh->disks) {
1868 		atomic_inc(&sh->count);
1869 		set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1870 		ops_complete_reconstruct(sh);
1871 		return;
1872 	}
1873 again:
1874 	count = 0;
1875 	xor_srcs = to_addr_page(percpu, j);
1876 	/* check if prexor is active which means only process blocks
1877 	 * that are part of a read-modify-write (written)
1878 	 */
1879 	if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1880 		prexor = 1;
1881 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1882 		for (i = disks; i--; ) {
1883 			struct r5dev *dev = &sh->dev[i];
1884 			if (head_sh->dev[i].written ||
1885 			    test_bit(R5_InJournal, &head_sh->dev[i].flags))
1886 				xor_srcs[count++] = dev->page;
1887 		}
1888 	} else {
1889 		xor_dest = sh->dev[pd_idx].page;
1890 		for (i = disks; i--; ) {
1891 			struct r5dev *dev = &sh->dev[i];
1892 			if (i != pd_idx)
1893 				xor_srcs[count++] = dev->page;
1894 		}
1895 	}
1896 
1897 	/* 1/ if we prexor'd then the dest is reused as a source
1898 	 * 2/ if we did not prexor then we are redoing the parity
1899 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1900 	 * for the synchronous xor case
1901 	 */
1902 	last_stripe = !head_sh->batch_head ||
1903 		list_first_entry(&sh->batch_list,
1904 				 struct stripe_head, batch_list) == head_sh;
1905 	if (last_stripe) {
1906 		flags = ASYNC_TX_ACK |
1907 			(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1908 
1909 		atomic_inc(&head_sh->count);
1910 		init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1911 				  to_addr_conv(sh, percpu, j));
1912 	} else {
1913 		flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1914 		init_async_submit(&submit, flags, tx, NULL, NULL,
1915 				  to_addr_conv(sh, percpu, j));
1916 	}
1917 
1918 	if (unlikely(count == 1))
1919 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1920 	else
1921 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1922 	if (!last_stripe) {
1923 		j++;
1924 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1925 				      batch_list);
1926 		goto again;
1927 	}
1928 }
1929 
1930 static void
1931 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1932 		     struct dma_async_tx_descriptor *tx)
1933 {
1934 	struct async_submit_ctl submit;
1935 	struct page **blocks;
1936 	int count, i, j = 0;
1937 	struct stripe_head *head_sh = sh;
1938 	int last_stripe;
1939 	int synflags;
1940 	unsigned long txflags;
1941 
1942 	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1943 
1944 	for (i = 0; i < sh->disks; i++) {
1945 		if (sh->pd_idx == i || sh->qd_idx == i)
1946 			continue;
1947 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1948 			break;
1949 	}
1950 	if (i >= sh->disks) {
1951 		atomic_inc(&sh->count);
1952 		set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1953 		set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1954 		ops_complete_reconstruct(sh);
1955 		return;
1956 	}
1957 
1958 again:
1959 	blocks = to_addr_page(percpu, j);
1960 
1961 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1962 		synflags = SYNDROME_SRC_WRITTEN;
1963 		txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1964 	} else {
1965 		synflags = SYNDROME_SRC_ALL;
1966 		txflags = ASYNC_TX_ACK;
1967 	}
1968 
1969 	count = set_syndrome_sources(blocks, sh, synflags);
1970 	last_stripe = !head_sh->batch_head ||
1971 		list_first_entry(&sh->batch_list,
1972 				 struct stripe_head, batch_list) == head_sh;
1973 
1974 	if (last_stripe) {
1975 		atomic_inc(&head_sh->count);
1976 		init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1977 				  head_sh, to_addr_conv(sh, percpu, j));
1978 	} else
1979 		init_async_submit(&submit, 0, tx, NULL, NULL,
1980 				  to_addr_conv(sh, percpu, j));
1981 	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1982 	if (!last_stripe) {
1983 		j++;
1984 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1985 				      batch_list);
1986 		goto again;
1987 	}
1988 }
1989 
1990 static void ops_complete_check(void *stripe_head_ref)
1991 {
1992 	struct stripe_head *sh = stripe_head_ref;
1993 
1994 	pr_debug("%s: stripe %llu\n", __func__,
1995 		(unsigned long long)sh->sector);
1996 
1997 	sh->check_state = check_state_check_result;
1998 	set_bit(STRIPE_HANDLE, &sh->state);
1999 	raid5_release_stripe(sh);
2000 }
2001 
2002 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
2003 {
2004 	int disks = sh->disks;
2005 	int pd_idx = sh->pd_idx;
2006 	int qd_idx = sh->qd_idx;
2007 	struct page *xor_dest;
2008 	struct page **xor_srcs = to_addr_page(percpu, 0);
2009 	struct dma_async_tx_descriptor *tx;
2010 	struct async_submit_ctl submit;
2011 	int count;
2012 	int i;
2013 
2014 	pr_debug("%s: stripe %llu\n", __func__,
2015 		(unsigned long long)sh->sector);
2016 
2017 	BUG_ON(sh->batch_head);
2018 	count = 0;
2019 	xor_dest = sh->dev[pd_idx].page;
2020 	xor_srcs[count++] = xor_dest;
2021 	for (i = disks; i--; ) {
2022 		if (i == pd_idx || i == qd_idx)
2023 			continue;
2024 		xor_srcs[count++] = sh->dev[i].page;
2025 	}
2026 
2027 	init_async_submit(&submit, 0, NULL, NULL, NULL,
2028 			  to_addr_conv(sh, percpu, 0));
2029 	tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
2030 			   &sh->ops.zero_sum_result, &submit);
2031 
2032 	atomic_inc(&sh->count);
2033 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
2034 	tx = async_trigger_callback(&submit);
2035 }
2036 
2037 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
2038 {
2039 	struct page **srcs = to_addr_page(percpu, 0);
2040 	struct async_submit_ctl submit;
2041 	int count;
2042 
2043 	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
2044 		(unsigned long long)sh->sector, checkp);
2045 
2046 	BUG_ON(sh->batch_head);
2047 	count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
2048 	if (!checkp)
2049 		srcs[count] = NULL;
2050 
2051 	atomic_inc(&sh->count);
2052 	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
2053 			  sh, to_addr_conv(sh, percpu, 0));
2054 	async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
2055 			   &sh->ops.zero_sum_result, percpu->spare_page, &submit);
2056 }
2057 
2058 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
2059 {
2060 	int overlap_clear = 0, i, disks = sh->disks;
2061 	struct dma_async_tx_descriptor *tx = NULL;
2062 	struct r5conf *conf = sh->raid_conf;
2063 	int level = conf->level;
2064 	struct raid5_percpu *percpu;
2065 	unsigned long cpu;
2066 
2067 	cpu = get_cpu();
2068 	percpu = per_cpu_ptr(conf->percpu, cpu);
2069 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
2070 		ops_run_biofill(sh);
2071 		overlap_clear++;
2072 	}
2073 
2074 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
2075 		if (level < 6)
2076 			tx = ops_run_compute5(sh, percpu);
2077 		else {
2078 			if (sh->ops.target2 < 0 || sh->ops.target < 0)
2079 				tx = ops_run_compute6_1(sh, percpu);
2080 			else
2081 				tx = ops_run_compute6_2(sh, percpu);
2082 		}
2083 		/* terminate the chain if reconstruct is not set to be run */
2084 		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
2085 			async_tx_ack(tx);
2086 	}
2087 
2088 	if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
2089 		if (level < 6)
2090 			tx = ops_run_prexor5(sh, percpu, tx);
2091 		else
2092 			tx = ops_run_prexor6(sh, percpu, tx);
2093 	}
2094 
2095 	if (test_bit(STRIPE_OP_PARTIAL_PARITY, &ops_request))
2096 		tx = ops_run_partial_parity(sh, percpu, tx);
2097 
2098 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
2099 		tx = ops_run_biodrain(sh, tx);
2100 		overlap_clear++;
2101 	}
2102 
2103 	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
2104 		if (level < 6)
2105 			ops_run_reconstruct5(sh, percpu, tx);
2106 		else
2107 			ops_run_reconstruct6(sh, percpu, tx);
2108 	}
2109 
2110 	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
2111 		if (sh->check_state == check_state_run)
2112 			ops_run_check_p(sh, percpu);
2113 		else if (sh->check_state == check_state_run_q)
2114 			ops_run_check_pq(sh, percpu, 0);
2115 		else if (sh->check_state == check_state_run_pq)
2116 			ops_run_check_pq(sh, percpu, 1);
2117 		else
2118 			BUG();
2119 	}
2120 
2121 	if (overlap_clear && !sh->batch_head)
2122 		for (i = disks; i--; ) {
2123 			struct r5dev *dev = &sh->dev[i];
2124 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
2125 				wake_up(&sh->raid_conf->wait_for_overlap);
2126 		}
2127 	put_cpu();
2128 }
2129 
2130 static void free_stripe(struct kmem_cache *sc, struct stripe_head *sh)
2131 {
2132 	if (sh->ppl_page)
2133 		__free_page(sh->ppl_page);
2134 	kmem_cache_free(sc, sh);
2135 }
2136 
2137 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
2138 	int disks, struct r5conf *conf)
2139 {
2140 	struct stripe_head *sh;
2141 	int i;
2142 
2143 	sh = kmem_cache_zalloc(sc, gfp);
2144 	if (sh) {
2145 		spin_lock_init(&sh->stripe_lock);
2146 		spin_lock_init(&sh->batch_lock);
2147 		INIT_LIST_HEAD(&sh->batch_list);
2148 		INIT_LIST_HEAD(&sh->lru);
2149 		INIT_LIST_HEAD(&sh->r5c);
2150 		INIT_LIST_HEAD(&sh->log_list);
2151 		atomic_set(&sh->count, 1);
2152 		sh->raid_conf = conf;
2153 		sh->log_start = MaxSector;
2154 		for (i = 0; i < disks; i++) {
2155 			struct r5dev *dev = &sh->dev[i];
2156 
2157 			bio_init(&dev->req, &dev->vec, 1);
2158 			bio_init(&dev->rreq, &dev->rvec, 1);
2159 		}
2160 
2161 		if (raid5_has_ppl(conf)) {
2162 			sh->ppl_page = alloc_page(gfp);
2163 			if (!sh->ppl_page) {
2164 				free_stripe(sc, sh);
2165 				sh = NULL;
2166 			}
2167 		}
2168 	}
2169 	return sh;
2170 }
2171 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2172 {
2173 	struct stripe_head *sh;
2174 
2175 	sh = alloc_stripe(conf->slab_cache, gfp, conf->pool_size, conf);
2176 	if (!sh)
2177 		return 0;
2178 
2179 	if (grow_buffers(sh, gfp)) {
2180 		shrink_buffers(sh);
2181 		free_stripe(conf->slab_cache, sh);
2182 		return 0;
2183 	}
2184 	sh->hash_lock_index =
2185 		conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2186 	/* we just created an active stripe so... */
2187 	atomic_inc(&conf->active_stripes);
2188 
2189 	raid5_release_stripe(sh);
2190 	conf->max_nr_stripes++;
2191 	return 1;
2192 }
2193 
2194 static int grow_stripes(struct r5conf *conf, int num)
2195 {
2196 	struct kmem_cache *sc;
2197 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
2198 
2199 	if (conf->mddev->gendisk)
2200 		sprintf(conf->cache_name[0],
2201 			"raid%d-%s", conf->level, mdname(conf->mddev));
2202 	else
2203 		sprintf(conf->cache_name[0],
2204 			"raid%d-%p", conf->level, conf->mddev);
2205 	sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
2206 
2207 	conf->active_name = 0;
2208 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
2209 			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2210 			       0, 0, NULL);
2211 	if (!sc)
2212 		return 1;
2213 	conf->slab_cache = sc;
2214 	conf->pool_size = devs;
2215 	while (num--)
2216 		if (!grow_one_stripe(conf, GFP_KERNEL))
2217 			return 1;
2218 
2219 	return 0;
2220 }
2221 
2222 /**
2223  * scribble_len - return the required size of the scribble region
2224  * @num - total number of disks in the array
2225  *
2226  * The size must be enough to contain:
2227  * 1/ a struct page pointer for each device in the array +2
2228  * 2/ room to convert each entry in (1) to its corresponding dma
2229  *    (dma_map_page()) or page (page_address()) address.
2230  *
2231  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2232  * calculate over all devices (not just the data blocks), using zeros in place
2233  * of the P and Q blocks.
2234  */
2235 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2236 {
2237 	struct flex_array *ret;
2238 	size_t len;
2239 
2240 	len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2241 	ret = flex_array_alloc(len, cnt, flags);
2242 	if (!ret)
2243 		return NULL;
2244 	/* always prealloc all elements, so no locking is required */
2245 	if (flex_array_prealloc(ret, 0, cnt, flags)) {
2246 		flex_array_free(ret);
2247 		return NULL;
2248 	}
2249 	return ret;
2250 }
2251 
2252 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2253 {
2254 	unsigned long cpu;
2255 	int err = 0;
2256 
2257 	/*
2258 	 * Never shrink. And mddev_suspend() could deadlock if this is called
2259 	 * from raid5d. In that case, scribble_disks and scribble_sectors
2260 	 * should equal to new_disks and new_sectors
2261 	 */
2262 	if (conf->scribble_disks >= new_disks &&
2263 	    conf->scribble_sectors >= new_sectors)
2264 		return 0;
2265 	mddev_suspend(conf->mddev);
2266 	get_online_cpus();
2267 	for_each_present_cpu(cpu) {
2268 		struct raid5_percpu *percpu;
2269 		struct flex_array *scribble;
2270 
2271 		percpu = per_cpu_ptr(conf->percpu, cpu);
2272 		scribble = scribble_alloc(new_disks,
2273 					  new_sectors / STRIPE_SECTORS,
2274 					  GFP_NOIO);
2275 
2276 		if (scribble) {
2277 			flex_array_free(percpu->scribble);
2278 			percpu->scribble = scribble;
2279 		} else {
2280 			err = -ENOMEM;
2281 			break;
2282 		}
2283 	}
2284 	put_online_cpus();
2285 	mddev_resume(conf->mddev);
2286 	if (!err) {
2287 		conf->scribble_disks = new_disks;
2288 		conf->scribble_sectors = new_sectors;
2289 	}
2290 	return err;
2291 }
2292 
2293 static int resize_stripes(struct r5conf *conf, int newsize)
2294 {
2295 	/* Make all the stripes able to hold 'newsize' devices.
2296 	 * New slots in each stripe get 'page' set to a new page.
2297 	 *
2298 	 * This happens in stages:
2299 	 * 1/ create a new kmem_cache and allocate the required number of
2300 	 *    stripe_heads.
2301 	 * 2/ gather all the old stripe_heads and transfer the pages across
2302 	 *    to the new stripe_heads.  This will have the side effect of
2303 	 *    freezing the array as once all stripe_heads have been collected,
2304 	 *    no IO will be possible.  Old stripe heads are freed once their
2305 	 *    pages have been transferred over, and the old kmem_cache is
2306 	 *    freed when all stripes are done.
2307 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2308 	 *    we simple return a failure status - no need to clean anything up.
2309 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
2310 	 *    If this fails, we don't bother trying the shrink the
2311 	 *    stripe_heads down again, we just leave them as they are.
2312 	 *    As each stripe_head is processed the new one is released into
2313 	 *    active service.
2314 	 *
2315 	 * Once step2 is started, we cannot afford to wait for a write,
2316 	 * so we use GFP_NOIO allocations.
2317 	 */
2318 	struct stripe_head *osh, *nsh;
2319 	LIST_HEAD(newstripes);
2320 	struct disk_info *ndisks;
2321 	int err = 0;
2322 	struct kmem_cache *sc;
2323 	int i;
2324 	int hash, cnt;
2325 
2326 	md_allow_write(conf->mddev);
2327 
2328 	/* Step 1 */
2329 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2330 			       sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2331 			       0, 0, NULL);
2332 	if (!sc)
2333 		return -ENOMEM;
2334 
2335 	/* Need to ensure auto-resizing doesn't interfere */
2336 	mutex_lock(&conf->cache_size_mutex);
2337 
2338 	for (i = conf->max_nr_stripes; i; i--) {
2339 		nsh = alloc_stripe(sc, GFP_KERNEL, newsize, conf);
2340 		if (!nsh)
2341 			break;
2342 
2343 		list_add(&nsh->lru, &newstripes);
2344 	}
2345 	if (i) {
2346 		/* didn't get enough, give up */
2347 		while (!list_empty(&newstripes)) {
2348 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
2349 			list_del(&nsh->lru);
2350 			free_stripe(sc, nsh);
2351 		}
2352 		kmem_cache_destroy(sc);
2353 		mutex_unlock(&conf->cache_size_mutex);
2354 		return -ENOMEM;
2355 	}
2356 	/* Step 2 - Must use GFP_NOIO now.
2357 	 * OK, we have enough stripes, start collecting inactive
2358 	 * stripes and copying them over
2359 	 */
2360 	hash = 0;
2361 	cnt = 0;
2362 	list_for_each_entry(nsh, &newstripes, lru) {
2363 		lock_device_hash_lock(conf, hash);
2364 		wait_event_cmd(conf->wait_for_stripe,
2365 				    !list_empty(conf->inactive_list + hash),
2366 				    unlock_device_hash_lock(conf, hash),
2367 				    lock_device_hash_lock(conf, hash));
2368 		osh = get_free_stripe(conf, hash);
2369 		unlock_device_hash_lock(conf, hash);
2370 
2371 		for(i=0; i<conf->pool_size; i++) {
2372 			nsh->dev[i].page = osh->dev[i].page;
2373 			nsh->dev[i].orig_page = osh->dev[i].page;
2374 		}
2375 		nsh->hash_lock_index = hash;
2376 		free_stripe(conf->slab_cache, osh);
2377 		cnt++;
2378 		if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2379 		    !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2380 			hash++;
2381 			cnt = 0;
2382 		}
2383 	}
2384 	kmem_cache_destroy(conf->slab_cache);
2385 
2386 	/* Step 3.
2387 	 * At this point, we are holding all the stripes so the array
2388 	 * is completely stalled, so now is a good time to resize
2389 	 * conf->disks and the scribble region
2390 	 */
2391 	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2392 	if (ndisks) {
2393 		for (i = 0; i < conf->pool_size; i++)
2394 			ndisks[i] = conf->disks[i];
2395 
2396 		for (i = conf->pool_size; i < newsize; i++) {
2397 			ndisks[i].extra_page = alloc_page(GFP_NOIO);
2398 			if (!ndisks[i].extra_page)
2399 				err = -ENOMEM;
2400 		}
2401 
2402 		if (err) {
2403 			for (i = conf->pool_size; i < newsize; i++)
2404 				if (ndisks[i].extra_page)
2405 					put_page(ndisks[i].extra_page);
2406 			kfree(ndisks);
2407 		} else {
2408 			kfree(conf->disks);
2409 			conf->disks = ndisks;
2410 		}
2411 	} else
2412 		err = -ENOMEM;
2413 
2414 	mutex_unlock(&conf->cache_size_mutex);
2415 
2416 	conf->slab_cache = sc;
2417 	conf->active_name = 1-conf->active_name;
2418 
2419 	/* Step 4, return new stripes to service */
2420 	while(!list_empty(&newstripes)) {
2421 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
2422 		list_del_init(&nsh->lru);
2423 
2424 		for (i=conf->raid_disks; i < newsize; i++)
2425 			if (nsh->dev[i].page == NULL) {
2426 				struct page *p = alloc_page(GFP_NOIO);
2427 				nsh->dev[i].page = p;
2428 				nsh->dev[i].orig_page = p;
2429 				if (!p)
2430 					err = -ENOMEM;
2431 			}
2432 		raid5_release_stripe(nsh);
2433 	}
2434 	/* critical section pass, GFP_NOIO no longer needed */
2435 
2436 	if (!err)
2437 		conf->pool_size = newsize;
2438 	return err;
2439 }
2440 
2441 static int drop_one_stripe(struct r5conf *conf)
2442 {
2443 	struct stripe_head *sh;
2444 	int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2445 
2446 	spin_lock_irq(conf->hash_locks + hash);
2447 	sh = get_free_stripe(conf, hash);
2448 	spin_unlock_irq(conf->hash_locks + hash);
2449 	if (!sh)
2450 		return 0;
2451 	BUG_ON(atomic_read(&sh->count));
2452 	shrink_buffers(sh);
2453 	free_stripe(conf->slab_cache, sh);
2454 	atomic_dec(&conf->active_stripes);
2455 	conf->max_nr_stripes--;
2456 	return 1;
2457 }
2458 
2459 static void shrink_stripes(struct r5conf *conf)
2460 {
2461 	while (conf->max_nr_stripes &&
2462 	       drop_one_stripe(conf))
2463 		;
2464 
2465 	kmem_cache_destroy(conf->slab_cache);
2466 	conf->slab_cache = NULL;
2467 }
2468 
2469 static void raid5_end_read_request(struct bio * bi)
2470 {
2471 	struct stripe_head *sh = bi->bi_private;
2472 	struct r5conf *conf = sh->raid_conf;
2473 	int disks = sh->disks, i;
2474 	char b[BDEVNAME_SIZE];
2475 	struct md_rdev *rdev = NULL;
2476 	sector_t s;
2477 
2478 	for (i=0 ; i<disks; i++)
2479 		if (bi == &sh->dev[i].req)
2480 			break;
2481 
2482 	pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2483 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2484 		bi->bi_status);
2485 	if (i == disks) {
2486 		bio_reset(bi);
2487 		BUG();
2488 		return;
2489 	}
2490 	if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2491 		/* If replacement finished while this request was outstanding,
2492 		 * 'replacement' might be NULL already.
2493 		 * In that case it moved down to 'rdev'.
2494 		 * rdev is not removed until all requests are finished.
2495 		 */
2496 		rdev = conf->disks[i].replacement;
2497 	if (!rdev)
2498 		rdev = conf->disks[i].rdev;
2499 
2500 	if (use_new_offset(conf, sh))
2501 		s = sh->sector + rdev->new_data_offset;
2502 	else
2503 		s = sh->sector + rdev->data_offset;
2504 	if (!bi->bi_status) {
2505 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
2506 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2507 			/* Note that this cannot happen on a
2508 			 * replacement device.  We just fail those on
2509 			 * any error
2510 			 */
2511 			pr_info_ratelimited(
2512 				"md/raid:%s: read error corrected (%lu sectors at %llu on %s)\n",
2513 				mdname(conf->mddev), STRIPE_SECTORS,
2514 				(unsigned long long)s,
2515 				bdevname(rdev->bdev, b));
2516 			atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2517 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2518 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2519 		} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2520 			clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2521 
2522 		if (test_bit(R5_InJournal, &sh->dev[i].flags))
2523 			/*
2524 			 * end read for a page in journal, this
2525 			 * must be preparing for prexor in rmw
2526 			 */
2527 			set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
2528 
2529 		if (atomic_read(&rdev->read_errors))
2530 			atomic_set(&rdev->read_errors, 0);
2531 	} else {
2532 		const char *bdn = bdevname(rdev->bdev, b);
2533 		int retry = 0;
2534 		int set_bad = 0;
2535 
2536 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2537 		atomic_inc(&rdev->read_errors);
2538 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2539 			pr_warn_ratelimited(
2540 				"md/raid:%s: read error on replacement device (sector %llu on %s).\n",
2541 				mdname(conf->mddev),
2542 				(unsigned long long)s,
2543 				bdn);
2544 		else if (conf->mddev->degraded >= conf->max_degraded) {
2545 			set_bad = 1;
2546 			pr_warn_ratelimited(
2547 				"md/raid:%s: read error not correctable (sector %llu on %s).\n",
2548 				mdname(conf->mddev),
2549 				(unsigned long long)s,
2550 				bdn);
2551 		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2552 			/* Oh, no!!! */
2553 			set_bad = 1;
2554 			pr_warn_ratelimited(
2555 				"md/raid:%s: read error NOT corrected!! (sector %llu on %s).\n",
2556 				mdname(conf->mddev),
2557 				(unsigned long long)s,
2558 				bdn);
2559 		} else if (atomic_read(&rdev->read_errors)
2560 			 > conf->max_nr_stripes)
2561 			pr_warn("md/raid:%s: Too many read errors, failing device %s.\n",
2562 			       mdname(conf->mddev), bdn);
2563 		else
2564 			retry = 1;
2565 		if (set_bad && test_bit(In_sync, &rdev->flags)
2566 		    && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2567 			retry = 1;
2568 		if (retry)
2569 			if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2570 				set_bit(R5_ReadError, &sh->dev[i].flags);
2571 				clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2572 			} else
2573 				set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2574 		else {
2575 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2576 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2577 			if (!(set_bad
2578 			      && test_bit(In_sync, &rdev->flags)
2579 			      && rdev_set_badblocks(
2580 				      rdev, sh->sector, STRIPE_SECTORS, 0)))
2581 				md_error(conf->mddev, rdev);
2582 		}
2583 	}
2584 	rdev_dec_pending(rdev, conf->mddev);
2585 	bio_reset(bi);
2586 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
2587 	set_bit(STRIPE_HANDLE, &sh->state);
2588 	raid5_release_stripe(sh);
2589 }
2590 
2591 static void raid5_end_write_request(struct bio *bi)
2592 {
2593 	struct stripe_head *sh = bi->bi_private;
2594 	struct r5conf *conf = sh->raid_conf;
2595 	int disks = sh->disks, i;
2596 	struct md_rdev *uninitialized_var(rdev);
2597 	sector_t first_bad;
2598 	int bad_sectors;
2599 	int replacement = 0;
2600 
2601 	for (i = 0 ; i < disks; i++) {
2602 		if (bi == &sh->dev[i].req) {
2603 			rdev = conf->disks[i].rdev;
2604 			break;
2605 		}
2606 		if (bi == &sh->dev[i].rreq) {
2607 			rdev = conf->disks[i].replacement;
2608 			if (rdev)
2609 				replacement = 1;
2610 			else
2611 				/* rdev was removed and 'replacement'
2612 				 * replaced it.  rdev is not removed
2613 				 * until all requests are finished.
2614 				 */
2615 				rdev = conf->disks[i].rdev;
2616 			break;
2617 		}
2618 	}
2619 	pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2620 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2621 		bi->bi_status);
2622 	if (i == disks) {
2623 		bio_reset(bi);
2624 		BUG();
2625 		return;
2626 	}
2627 
2628 	if (replacement) {
2629 		if (bi->bi_status)
2630 			md_error(conf->mddev, rdev);
2631 		else if (is_badblock(rdev, sh->sector,
2632 				     STRIPE_SECTORS,
2633 				     &first_bad, &bad_sectors))
2634 			set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2635 	} else {
2636 		if (bi->bi_status) {
2637 			set_bit(STRIPE_DEGRADED, &sh->state);
2638 			set_bit(WriteErrorSeen, &rdev->flags);
2639 			set_bit(R5_WriteError, &sh->dev[i].flags);
2640 			if (!test_and_set_bit(WantReplacement, &rdev->flags))
2641 				set_bit(MD_RECOVERY_NEEDED,
2642 					&rdev->mddev->recovery);
2643 		} else if (is_badblock(rdev, sh->sector,
2644 				       STRIPE_SECTORS,
2645 				       &first_bad, &bad_sectors)) {
2646 			set_bit(R5_MadeGood, &sh->dev[i].flags);
2647 			if (test_bit(R5_ReadError, &sh->dev[i].flags))
2648 				/* That was a successful write so make
2649 				 * sure it looks like we already did
2650 				 * a re-write.
2651 				 */
2652 				set_bit(R5_ReWrite, &sh->dev[i].flags);
2653 		}
2654 	}
2655 	rdev_dec_pending(rdev, conf->mddev);
2656 
2657 	if (sh->batch_head && bi->bi_status && !replacement)
2658 		set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2659 
2660 	bio_reset(bi);
2661 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2662 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2663 	set_bit(STRIPE_HANDLE, &sh->state);
2664 	raid5_release_stripe(sh);
2665 
2666 	if (sh->batch_head && sh != sh->batch_head)
2667 		raid5_release_stripe(sh->batch_head);
2668 }
2669 
2670 static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
2671 {
2672 	char b[BDEVNAME_SIZE];
2673 	struct r5conf *conf = mddev->private;
2674 	unsigned long flags;
2675 	pr_debug("raid456: error called\n");
2676 
2677 	spin_lock_irqsave(&conf->device_lock, flags);
2678 	clear_bit(In_sync, &rdev->flags);
2679 	mddev->degraded = raid5_calc_degraded(conf);
2680 	spin_unlock_irqrestore(&conf->device_lock, flags);
2681 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2682 
2683 	set_bit(Blocked, &rdev->flags);
2684 	set_bit(Faulty, &rdev->flags);
2685 	set_mask_bits(&mddev->sb_flags, 0,
2686 		      BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
2687 	pr_crit("md/raid:%s: Disk failure on %s, disabling device.\n"
2688 		"md/raid:%s: Operation continuing on %d devices.\n",
2689 		mdname(mddev),
2690 		bdevname(rdev->bdev, b),
2691 		mdname(mddev),
2692 		conf->raid_disks - mddev->degraded);
2693 	r5c_update_on_rdev_error(mddev, rdev);
2694 }
2695 
2696 /*
2697  * Input: a 'big' sector number,
2698  * Output: index of the data and parity disk, and the sector # in them.
2699  */
2700 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2701 			      int previous, int *dd_idx,
2702 			      struct stripe_head *sh)
2703 {
2704 	sector_t stripe, stripe2;
2705 	sector_t chunk_number;
2706 	unsigned int chunk_offset;
2707 	int pd_idx, qd_idx;
2708 	int ddf_layout = 0;
2709 	sector_t new_sector;
2710 	int algorithm = previous ? conf->prev_algo
2711 				 : conf->algorithm;
2712 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2713 					 : conf->chunk_sectors;
2714 	int raid_disks = previous ? conf->previous_raid_disks
2715 				  : conf->raid_disks;
2716 	int data_disks = raid_disks - conf->max_degraded;
2717 
2718 	/* First compute the information on this sector */
2719 
2720 	/*
2721 	 * Compute the chunk number and the sector offset inside the chunk
2722 	 */
2723 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
2724 	chunk_number = r_sector;
2725 
2726 	/*
2727 	 * Compute the stripe number
2728 	 */
2729 	stripe = chunk_number;
2730 	*dd_idx = sector_div(stripe, data_disks);
2731 	stripe2 = stripe;
2732 	/*
2733 	 * Select the parity disk based on the user selected algorithm.
2734 	 */
2735 	pd_idx = qd_idx = -1;
2736 	switch(conf->level) {
2737 	case 4:
2738 		pd_idx = data_disks;
2739 		break;
2740 	case 5:
2741 		switch (algorithm) {
2742 		case ALGORITHM_LEFT_ASYMMETRIC:
2743 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2744 			if (*dd_idx >= pd_idx)
2745 				(*dd_idx)++;
2746 			break;
2747 		case ALGORITHM_RIGHT_ASYMMETRIC:
2748 			pd_idx = sector_div(stripe2, raid_disks);
2749 			if (*dd_idx >= pd_idx)
2750 				(*dd_idx)++;
2751 			break;
2752 		case ALGORITHM_LEFT_SYMMETRIC:
2753 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2754 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2755 			break;
2756 		case ALGORITHM_RIGHT_SYMMETRIC:
2757 			pd_idx = sector_div(stripe2, raid_disks);
2758 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2759 			break;
2760 		case ALGORITHM_PARITY_0:
2761 			pd_idx = 0;
2762 			(*dd_idx)++;
2763 			break;
2764 		case ALGORITHM_PARITY_N:
2765 			pd_idx = data_disks;
2766 			break;
2767 		default:
2768 			BUG();
2769 		}
2770 		break;
2771 	case 6:
2772 
2773 		switch (algorithm) {
2774 		case ALGORITHM_LEFT_ASYMMETRIC:
2775 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2776 			qd_idx = pd_idx + 1;
2777 			if (pd_idx == raid_disks-1) {
2778 				(*dd_idx)++;	/* Q D D D P */
2779 				qd_idx = 0;
2780 			} else if (*dd_idx >= pd_idx)
2781 				(*dd_idx) += 2; /* D D P Q D */
2782 			break;
2783 		case ALGORITHM_RIGHT_ASYMMETRIC:
2784 			pd_idx = sector_div(stripe2, raid_disks);
2785 			qd_idx = pd_idx + 1;
2786 			if (pd_idx == raid_disks-1) {
2787 				(*dd_idx)++;	/* Q D D D P */
2788 				qd_idx = 0;
2789 			} else if (*dd_idx >= pd_idx)
2790 				(*dd_idx) += 2; /* D D P Q D */
2791 			break;
2792 		case ALGORITHM_LEFT_SYMMETRIC:
2793 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2794 			qd_idx = (pd_idx + 1) % raid_disks;
2795 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2796 			break;
2797 		case ALGORITHM_RIGHT_SYMMETRIC:
2798 			pd_idx = sector_div(stripe2, raid_disks);
2799 			qd_idx = (pd_idx + 1) % raid_disks;
2800 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2801 			break;
2802 
2803 		case ALGORITHM_PARITY_0:
2804 			pd_idx = 0;
2805 			qd_idx = 1;
2806 			(*dd_idx) += 2;
2807 			break;
2808 		case ALGORITHM_PARITY_N:
2809 			pd_idx = data_disks;
2810 			qd_idx = data_disks + 1;
2811 			break;
2812 
2813 		case ALGORITHM_ROTATING_ZERO_RESTART:
2814 			/* Exactly the same as RIGHT_ASYMMETRIC, but or
2815 			 * of blocks for computing Q is different.
2816 			 */
2817 			pd_idx = sector_div(stripe2, raid_disks);
2818 			qd_idx = pd_idx + 1;
2819 			if (pd_idx == raid_disks-1) {
2820 				(*dd_idx)++;	/* Q D D D P */
2821 				qd_idx = 0;
2822 			} else if (*dd_idx >= pd_idx)
2823 				(*dd_idx) += 2; /* D D P Q D */
2824 			ddf_layout = 1;
2825 			break;
2826 
2827 		case ALGORITHM_ROTATING_N_RESTART:
2828 			/* Same a left_asymmetric, by first stripe is
2829 			 * D D D P Q  rather than
2830 			 * Q D D D P
2831 			 */
2832 			stripe2 += 1;
2833 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2834 			qd_idx = pd_idx + 1;
2835 			if (pd_idx == raid_disks-1) {
2836 				(*dd_idx)++;	/* Q D D D P */
2837 				qd_idx = 0;
2838 			} else if (*dd_idx >= pd_idx)
2839 				(*dd_idx) += 2; /* D D P Q D */
2840 			ddf_layout = 1;
2841 			break;
2842 
2843 		case ALGORITHM_ROTATING_N_CONTINUE:
2844 			/* Same as left_symmetric but Q is before P */
2845 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2846 			qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2847 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2848 			ddf_layout = 1;
2849 			break;
2850 
2851 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2852 			/* RAID5 left_asymmetric, with Q on last device */
2853 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2854 			if (*dd_idx >= pd_idx)
2855 				(*dd_idx)++;
2856 			qd_idx = raid_disks - 1;
2857 			break;
2858 
2859 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2860 			pd_idx = sector_div(stripe2, raid_disks-1);
2861 			if (*dd_idx >= pd_idx)
2862 				(*dd_idx)++;
2863 			qd_idx = raid_disks - 1;
2864 			break;
2865 
2866 		case ALGORITHM_LEFT_SYMMETRIC_6:
2867 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2868 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2869 			qd_idx = raid_disks - 1;
2870 			break;
2871 
2872 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2873 			pd_idx = sector_div(stripe2, raid_disks-1);
2874 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2875 			qd_idx = raid_disks - 1;
2876 			break;
2877 
2878 		case ALGORITHM_PARITY_0_6:
2879 			pd_idx = 0;
2880 			(*dd_idx)++;
2881 			qd_idx = raid_disks - 1;
2882 			break;
2883 
2884 		default:
2885 			BUG();
2886 		}
2887 		break;
2888 	}
2889 
2890 	if (sh) {
2891 		sh->pd_idx = pd_idx;
2892 		sh->qd_idx = qd_idx;
2893 		sh->ddf_layout = ddf_layout;
2894 	}
2895 	/*
2896 	 * Finally, compute the new sector number
2897 	 */
2898 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2899 	return new_sector;
2900 }
2901 
2902 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
2903 {
2904 	struct r5conf *conf = sh->raid_conf;
2905 	int raid_disks = sh->disks;
2906 	int data_disks = raid_disks - conf->max_degraded;
2907 	sector_t new_sector = sh->sector, check;
2908 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2909 					 : conf->chunk_sectors;
2910 	int algorithm = previous ? conf->prev_algo
2911 				 : conf->algorithm;
2912 	sector_t stripe;
2913 	int chunk_offset;
2914 	sector_t chunk_number;
2915 	int dummy1, dd_idx = i;
2916 	sector_t r_sector;
2917 	struct stripe_head sh2;
2918 
2919 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
2920 	stripe = new_sector;
2921 
2922 	if (i == sh->pd_idx)
2923 		return 0;
2924 	switch(conf->level) {
2925 	case 4: break;
2926 	case 5:
2927 		switch (algorithm) {
2928 		case ALGORITHM_LEFT_ASYMMETRIC:
2929 		case ALGORITHM_RIGHT_ASYMMETRIC:
2930 			if (i > sh->pd_idx)
2931 				i--;
2932 			break;
2933 		case ALGORITHM_LEFT_SYMMETRIC:
2934 		case ALGORITHM_RIGHT_SYMMETRIC:
2935 			if (i < sh->pd_idx)
2936 				i += raid_disks;
2937 			i -= (sh->pd_idx + 1);
2938 			break;
2939 		case ALGORITHM_PARITY_0:
2940 			i -= 1;
2941 			break;
2942 		case ALGORITHM_PARITY_N:
2943 			break;
2944 		default:
2945 			BUG();
2946 		}
2947 		break;
2948 	case 6:
2949 		if (i == sh->qd_idx)
2950 			return 0; /* It is the Q disk */
2951 		switch (algorithm) {
2952 		case ALGORITHM_LEFT_ASYMMETRIC:
2953 		case ALGORITHM_RIGHT_ASYMMETRIC:
2954 		case ALGORITHM_ROTATING_ZERO_RESTART:
2955 		case ALGORITHM_ROTATING_N_RESTART:
2956 			if (sh->pd_idx == raid_disks-1)
2957 				i--;	/* Q D D D P */
2958 			else if (i > sh->pd_idx)
2959 				i -= 2; /* D D P Q D */
2960 			break;
2961 		case ALGORITHM_LEFT_SYMMETRIC:
2962 		case ALGORITHM_RIGHT_SYMMETRIC:
2963 			if (sh->pd_idx == raid_disks-1)
2964 				i--; /* Q D D D P */
2965 			else {
2966 				/* D D P Q D */
2967 				if (i < sh->pd_idx)
2968 					i += raid_disks;
2969 				i -= (sh->pd_idx + 2);
2970 			}
2971 			break;
2972 		case ALGORITHM_PARITY_0:
2973 			i -= 2;
2974 			break;
2975 		case ALGORITHM_PARITY_N:
2976 			break;
2977 		case ALGORITHM_ROTATING_N_CONTINUE:
2978 			/* Like left_symmetric, but P is before Q */
2979 			if (sh->pd_idx == 0)
2980 				i--;	/* P D D D Q */
2981 			else {
2982 				/* D D Q P D */
2983 				if (i < sh->pd_idx)
2984 					i += raid_disks;
2985 				i -= (sh->pd_idx + 1);
2986 			}
2987 			break;
2988 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2989 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2990 			if (i > sh->pd_idx)
2991 				i--;
2992 			break;
2993 		case ALGORITHM_LEFT_SYMMETRIC_6:
2994 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2995 			if (i < sh->pd_idx)
2996 				i += data_disks + 1;
2997 			i -= (sh->pd_idx + 1);
2998 			break;
2999 		case ALGORITHM_PARITY_0_6:
3000 			i -= 1;
3001 			break;
3002 		default:
3003 			BUG();
3004 		}
3005 		break;
3006 	}
3007 
3008 	chunk_number = stripe * data_disks + i;
3009 	r_sector = chunk_number * sectors_per_chunk + chunk_offset;
3010 
3011 	check = raid5_compute_sector(conf, r_sector,
3012 				     previous, &dummy1, &sh2);
3013 	if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
3014 		|| sh2.qd_idx != sh->qd_idx) {
3015 		pr_warn("md/raid:%s: compute_blocknr: map not correct\n",
3016 			mdname(conf->mddev));
3017 		return 0;
3018 	}
3019 	return r_sector;
3020 }
3021 
3022 /*
3023  * There are cases where we want handle_stripe_dirtying() and
3024  * schedule_reconstruction() to delay towrite to some dev of a stripe.
3025  *
3026  * This function checks whether we want to delay the towrite. Specifically,
3027  * we delay the towrite when:
3028  *
3029  *   1. degraded stripe has a non-overwrite to the missing dev, AND this
3030  *      stripe has data in journal (for other devices).
3031  *
3032  *      In this case, when reading data for the non-overwrite dev, it is
3033  *      necessary to handle complex rmw of write back cache (prexor with
3034  *      orig_page, and xor with page). To keep read path simple, we would
3035  *      like to flush data in journal to RAID disks first, so complex rmw
3036  *      is handled in the write patch (handle_stripe_dirtying).
3037  *
3038  *   2. when journal space is critical (R5C_LOG_CRITICAL=1)
3039  *
3040  *      It is important to be able to flush all stripes in raid5-cache.
3041  *      Therefore, we need reserve some space on the journal device for
3042  *      these flushes. If flush operation includes pending writes to the
3043  *      stripe, we need to reserve (conf->raid_disk + 1) pages per stripe
3044  *      for the flush out. If we exclude these pending writes from flush
3045  *      operation, we only need (conf->max_degraded + 1) pages per stripe.
3046  *      Therefore, excluding pending writes in these cases enables more
3047  *      efficient use of the journal device.
3048  *
3049  *      Note: To make sure the stripe makes progress, we only delay
3050  *      towrite for stripes with data already in journal (injournal > 0).
3051  *      When LOG_CRITICAL, stripes with injournal == 0 will be sent to
3052  *      no_space_stripes list.
3053  *
3054  *   3. during journal failure
3055  *      In journal failure, we try to flush all cached data to raid disks
3056  *      based on data in stripe cache. The array is read-only to upper
3057  *      layers, so we would skip all pending writes.
3058  *
3059  */
3060 static inline bool delay_towrite(struct r5conf *conf,
3061 				 struct r5dev *dev,
3062 				 struct stripe_head_state *s)
3063 {
3064 	/* case 1 above */
3065 	if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3066 	    !test_bit(R5_Insync, &dev->flags) && s->injournal)
3067 		return true;
3068 	/* case 2 above */
3069 	if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
3070 	    s->injournal > 0)
3071 		return true;
3072 	/* case 3 above */
3073 	if (s->log_failed && s->injournal)
3074 		return true;
3075 	return false;
3076 }
3077 
3078 static void
3079 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
3080 			 int rcw, int expand)
3081 {
3082 	int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
3083 	struct r5conf *conf = sh->raid_conf;
3084 	int level = conf->level;
3085 
3086 	if (rcw) {
3087 		/*
3088 		 * In some cases, handle_stripe_dirtying initially decided to
3089 		 * run rmw and allocates extra page for prexor. However, rcw is
3090 		 * cheaper later on. We need to free the extra page now,
3091 		 * because we won't be able to do that in ops_complete_prexor().
3092 		 */
3093 		r5c_release_extra_page(sh);
3094 
3095 		for (i = disks; i--; ) {
3096 			struct r5dev *dev = &sh->dev[i];
3097 
3098 			if (dev->towrite && !delay_towrite(conf, dev, s)) {
3099 				set_bit(R5_LOCKED, &dev->flags);
3100 				set_bit(R5_Wantdrain, &dev->flags);
3101 				if (!expand)
3102 					clear_bit(R5_UPTODATE, &dev->flags);
3103 				s->locked++;
3104 			} else if (test_bit(R5_InJournal, &dev->flags)) {
3105 				set_bit(R5_LOCKED, &dev->flags);
3106 				s->locked++;
3107 			}
3108 		}
3109 		/* if we are not expanding this is a proper write request, and
3110 		 * there will be bios with new data to be drained into the
3111 		 * stripe cache
3112 		 */
3113 		if (!expand) {
3114 			if (!s->locked)
3115 				/* False alarm, nothing to do */
3116 				return;
3117 			sh->reconstruct_state = reconstruct_state_drain_run;
3118 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3119 		} else
3120 			sh->reconstruct_state = reconstruct_state_run;
3121 
3122 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3123 
3124 		if (s->locked + conf->max_degraded == disks)
3125 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
3126 				atomic_inc(&conf->pending_full_writes);
3127 	} else {
3128 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
3129 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
3130 		BUG_ON(level == 6 &&
3131 			(!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
3132 			   test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
3133 
3134 		for (i = disks; i--; ) {
3135 			struct r5dev *dev = &sh->dev[i];
3136 			if (i == pd_idx || i == qd_idx)
3137 				continue;
3138 
3139 			if (dev->towrite &&
3140 			    (test_bit(R5_UPTODATE, &dev->flags) ||
3141 			     test_bit(R5_Wantcompute, &dev->flags))) {
3142 				set_bit(R5_Wantdrain, &dev->flags);
3143 				set_bit(R5_LOCKED, &dev->flags);
3144 				clear_bit(R5_UPTODATE, &dev->flags);
3145 				s->locked++;
3146 			} else if (test_bit(R5_InJournal, &dev->flags)) {
3147 				set_bit(R5_LOCKED, &dev->flags);
3148 				s->locked++;
3149 			}
3150 		}
3151 		if (!s->locked)
3152 			/* False alarm - nothing to do */
3153 			return;
3154 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
3155 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
3156 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3157 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3158 	}
3159 
3160 	/* keep the parity disk(s) locked while asynchronous operations
3161 	 * are in flight
3162 	 */
3163 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
3164 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3165 	s->locked++;
3166 
3167 	if (level == 6) {
3168 		int qd_idx = sh->qd_idx;
3169 		struct r5dev *dev = &sh->dev[qd_idx];
3170 
3171 		set_bit(R5_LOCKED, &dev->flags);
3172 		clear_bit(R5_UPTODATE, &dev->flags);
3173 		s->locked++;
3174 	}
3175 
3176 	if (raid5_has_ppl(sh->raid_conf) && sh->ppl_page &&
3177 	    test_bit(STRIPE_OP_BIODRAIN, &s->ops_request) &&
3178 	    !test_bit(STRIPE_FULL_WRITE, &sh->state) &&
3179 	    test_bit(R5_Insync, &sh->dev[pd_idx].flags))
3180 		set_bit(STRIPE_OP_PARTIAL_PARITY, &s->ops_request);
3181 
3182 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
3183 		__func__, (unsigned long long)sh->sector,
3184 		s->locked, s->ops_request);
3185 }
3186 
3187 /*
3188  * Each stripe/dev can have one or more bion attached.
3189  * toread/towrite point to the first in a chain.
3190  * The bi_next chain must be in order.
3191  */
3192 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
3193 			  int forwrite, int previous)
3194 {
3195 	struct bio **bip;
3196 	struct r5conf *conf = sh->raid_conf;
3197 	int firstwrite=0;
3198 
3199 	pr_debug("adding bi b#%llu to stripe s#%llu\n",
3200 		(unsigned long long)bi->bi_iter.bi_sector,
3201 		(unsigned long long)sh->sector);
3202 
3203 	spin_lock_irq(&sh->stripe_lock);
3204 	/* Don't allow new IO added to stripes in batch list */
3205 	if (sh->batch_head)
3206 		goto overlap;
3207 	if (forwrite) {
3208 		bip = &sh->dev[dd_idx].towrite;
3209 		if (*bip == NULL)
3210 			firstwrite = 1;
3211 	} else
3212 		bip = &sh->dev[dd_idx].toread;
3213 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
3214 		if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
3215 			goto overlap;
3216 		bip = & (*bip)->bi_next;
3217 	}
3218 	if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
3219 		goto overlap;
3220 
3221 	if (forwrite && raid5_has_ppl(conf)) {
3222 		/*
3223 		 * With PPL only writes to consecutive data chunks within a
3224 		 * stripe are allowed because for a single stripe_head we can
3225 		 * only have one PPL entry at a time, which describes one data
3226 		 * range. Not really an overlap, but wait_for_overlap can be
3227 		 * used to handle this.
3228 		 */
3229 		sector_t sector;
3230 		sector_t first = 0;
3231 		sector_t last = 0;
3232 		int count = 0;
3233 		int i;
3234 
3235 		for (i = 0; i < sh->disks; i++) {
3236 			if (i != sh->pd_idx &&
3237 			    (i == dd_idx || sh->dev[i].towrite)) {
3238 				sector = sh->dev[i].sector;
3239 				if (count == 0 || sector < first)
3240 					first = sector;
3241 				if (sector > last)
3242 					last = sector;
3243 				count++;
3244 			}
3245 		}
3246 
3247 		if (first + conf->chunk_sectors * (count - 1) != last)
3248 			goto overlap;
3249 	}
3250 
3251 	if (!forwrite || previous)
3252 		clear_bit(STRIPE_BATCH_READY, &sh->state);
3253 
3254 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3255 	if (*bip)
3256 		bi->bi_next = *bip;
3257 	*bip = bi;
3258 	bio_inc_remaining(bi);
3259 	md_write_inc(conf->mddev, bi);
3260 
3261 	if (forwrite) {
3262 		/* check if page is covered */
3263 		sector_t sector = sh->dev[dd_idx].sector;
3264 		for (bi=sh->dev[dd_idx].towrite;
3265 		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
3266 			     bi && bi->bi_iter.bi_sector <= sector;
3267 		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
3268 			if (bio_end_sector(bi) >= sector)
3269 				sector = bio_end_sector(bi);
3270 		}
3271 		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
3272 			if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3273 				sh->overwrite_disks++;
3274 	}
3275 
3276 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3277 		(unsigned long long)(*bip)->bi_iter.bi_sector,
3278 		(unsigned long long)sh->sector, dd_idx);
3279 
3280 	if (conf->mddev->bitmap && firstwrite) {
3281 		/* Cannot hold spinlock over bitmap_startwrite,
3282 		 * but must ensure this isn't added to a batch until
3283 		 * we have added to the bitmap and set bm_seq.
3284 		 * So set STRIPE_BITMAP_PENDING to prevent
3285 		 * batching.
3286 		 * If multiple add_stripe_bio() calls race here they
3287 		 * much all set STRIPE_BITMAP_PENDING.  So only the first one
3288 		 * to complete "bitmap_startwrite" gets to set
3289 		 * STRIPE_BIT_DELAY.  This is important as once a stripe
3290 		 * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3291 		 * any more.
3292 		 */
3293 		set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3294 		spin_unlock_irq(&sh->stripe_lock);
3295 		bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3296 				  STRIPE_SECTORS, 0);
3297 		spin_lock_irq(&sh->stripe_lock);
3298 		clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3299 		if (!sh->batch_head) {
3300 			sh->bm_seq = conf->seq_flush+1;
3301 			set_bit(STRIPE_BIT_DELAY, &sh->state);
3302 		}
3303 	}
3304 	spin_unlock_irq(&sh->stripe_lock);
3305 
3306 	if (stripe_can_batch(sh))
3307 		stripe_add_to_batch_list(conf, sh);
3308 	return 1;
3309 
3310  overlap:
3311 	set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3312 	spin_unlock_irq(&sh->stripe_lock);
3313 	return 0;
3314 }
3315 
3316 static void end_reshape(struct r5conf *conf);
3317 
3318 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3319 			    struct stripe_head *sh)
3320 {
3321 	int sectors_per_chunk =
3322 		previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3323 	int dd_idx;
3324 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
3325 	int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3326 
3327 	raid5_compute_sector(conf,
3328 			     stripe * (disks - conf->max_degraded)
3329 			     *sectors_per_chunk + chunk_offset,
3330 			     previous,
3331 			     &dd_idx, sh);
3332 }
3333 
3334 static void
3335 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3336 		     struct stripe_head_state *s, int disks)
3337 {
3338 	int i;
3339 	BUG_ON(sh->batch_head);
3340 	for (i = disks; i--; ) {
3341 		struct bio *bi;
3342 		int bitmap_end = 0;
3343 
3344 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3345 			struct md_rdev *rdev;
3346 			rcu_read_lock();
3347 			rdev = rcu_dereference(conf->disks[i].rdev);
3348 			if (rdev && test_bit(In_sync, &rdev->flags) &&
3349 			    !test_bit(Faulty, &rdev->flags))
3350 				atomic_inc(&rdev->nr_pending);
3351 			else
3352 				rdev = NULL;
3353 			rcu_read_unlock();
3354 			if (rdev) {
3355 				if (!rdev_set_badblocks(
3356 					    rdev,
3357 					    sh->sector,
3358 					    STRIPE_SECTORS, 0))
3359 					md_error(conf->mddev, rdev);
3360 				rdev_dec_pending(rdev, conf->mddev);
3361 			}
3362 		}
3363 		spin_lock_irq(&sh->stripe_lock);
3364 		/* fail all writes first */
3365 		bi = sh->dev[i].towrite;
3366 		sh->dev[i].towrite = NULL;
3367 		sh->overwrite_disks = 0;
3368 		spin_unlock_irq(&sh->stripe_lock);
3369 		if (bi)
3370 			bitmap_end = 1;
3371 
3372 		log_stripe_write_finished(sh);
3373 
3374 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3375 			wake_up(&conf->wait_for_overlap);
3376 
3377 		while (bi && bi->bi_iter.bi_sector <
3378 			sh->dev[i].sector + STRIPE_SECTORS) {
3379 			struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3380 
3381 			md_write_end(conf->mddev);
3382 			bio_io_error(bi);
3383 			bi = nextbi;
3384 		}
3385 		if (bitmap_end)
3386 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3387 				STRIPE_SECTORS, 0, 0);
3388 		bitmap_end = 0;
3389 		/* and fail all 'written' */
3390 		bi = sh->dev[i].written;
3391 		sh->dev[i].written = NULL;
3392 		if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3393 			WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3394 			sh->dev[i].page = sh->dev[i].orig_page;
3395 		}
3396 
3397 		if (bi) bitmap_end = 1;
3398 		while (bi && bi->bi_iter.bi_sector <
3399 		       sh->dev[i].sector + STRIPE_SECTORS) {
3400 			struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3401 
3402 			md_write_end(conf->mddev);
3403 			bio_io_error(bi);
3404 			bi = bi2;
3405 		}
3406 
3407 		/* fail any reads if this device is non-operational and
3408 		 * the data has not reached the cache yet.
3409 		 */
3410 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3411 		    s->failed > conf->max_degraded &&
3412 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3413 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
3414 			spin_lock_irq(&sh->stripe_lock);
3415 			bi = sh->dev[i].toread;
3416 			sh->dev[i].toread = NULL;
3417 			spin_unlock_irq(&sh->stripe_lock);
3418 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3419 				wake_up(&conf->wait_for_overlap);
3420 			if (bi)
3421 				s->to_read--;
3422 			while (bi && bi->bi_iter.bi_sector <
3423 			       sh->dev[i].sector + STRIPE_SECTORS) {
3424 				struct bio *nextbi =
3425 					r5_next_bio(bi, sh->dev[i].sector);
3426 
3427 				bio_io_error(bi);
3428 				bi = nextbi;
3429 			}
3430 		}
3431 		if (bitmap_end)
3432 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3433 					STRIPE_SECTORS, 0, 0);
3434 		/* If we were in the middle of a write the parity block might
3435 		 * still be locked - so just clear all R5_LOCKED flags
3436 		 */
3437 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
3438 	}
3439 	s->to_write = 0;
3440 	s->written = 0;
3441 
3442 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3443 		if (atomic_dec_and_test(&conf->pending_full_writes))
3444 			md_wakeup_thread(conf->mddev->thread);
3445 }
3446 
3447 static void
3448 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3449 		   struct stripe_head_state *s)
3450 {
3451 	int abort = 0;
3452 	int i;
3453 
3454 	BUG_ON(sh->batch_head);
3455 	clear_bit(STRIPE_SYNCING, &sh->state);
3456 	if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3457 		wake_up(&conf->wait_for_overlap);
3458 	s->syncing = 0;
3459 	s->replacing = 0;
3460 	/* There is nothing more to do for sync/check/repair.
3461 	 * Don't even need to abort as that is handled elsewhere
3462 	 * if needed, and not always wanted e.g. if there is a known
3463 	 * bad block here.
3464 	 * For recover/replace we need to record a bad block on all
3465 	 * non-sync devices, or abort the recovery
3466 	 */
3467 	if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3468 		/* During recovery devices cannot be removed, so
3469 		 * locking and refcounting of rdevs is not needed
3470 		 */
3471 		rcu_read_lock();
3472 		for (i = 0; i < conf->raid_disks; i++) {
3473 			struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
3474 			if (rdev
3475 			    && !test_bit(Faulty, &rdev->flags)
3476 			    && !test_bit(In_sync, &rdev->flags)
3477 			    && !rdev_set_badblocks(rdev, sh->sector,
3478 						   STRIPE_SECTORS, 0))
3479 				abort = 1;
3480 			rdev = rcu_dereference(conf->disks[i].replacement);
3481 			if (rdev
3482 			    && !test_bit(Faulty, &rdev->flags)
3483 			    && !test_bit(In_sync, &rdev->flags)
3484 			    && !rdev_set_badblocks(rdev, sh->sector,
3485 						   STRIPE_SECTORS, 0))
3486 				abort = 1;
3487 		}
3488 		rcu_read_unlock();
3489 		if (abort)
3490 			conf->recovery_disabled =
3491 				conf->mddev->recovery_disabled;
3492 	}
3493 	md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3494 }
3495 
3496 static int want_replace(struct stripe_head *sh, int disk_idx)
3497 {
3498 	struct md_rdev *rdev;
3499 	int rv = 0;
3500 
3501 	rcu_read_lock();
3502 	rdev = rcu_dereference(sh->raid_conf->disks[disk_idx].replacement);
3503 	if (rdev
3504 	    && !test_bit(Faulty, &rdev->flags)
3505 	    && !test_bit(In_sync, &rdev->flags)
3506 	    && (rdev->recovery_offset <= sh->sector
3507 		|| rdev->mddev->recovery_cp <= sh->sector))
3508 		rv = 1;
3509 	rcu_read_unlock();
3510 	return rv;
3511 }
3512 
3513 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3514 			   int disk_idx, int disks)
3515 {
3516 	struct r5dev *dev = &sh->dev[disk_idx];
3517 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3518 				  &sh->dev[s->failed_num[1]] };
3519 	int i;
3520 
3521 
3522 	if (test_bit(R5_LOCKED, &dev->flags) ||
3523 	    test_bit(R5_UPTODATE, &dev->flags))
3524 		/* No point reading this as we already have it or have
3525 		 * decided to get it.
3526 		 */
3527 		return 0;
3528 
3529 	if (dev->toread ||
3530 	    (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3531 		/* We need this block to directly satisfy a request */
3532 		return 1;
3533 
3534 	if (s->syncing || s->expanding ||
3535 	    (s->replacing && want_replace(sh, disk_idx)))
3536 		/* When syncing, or expanding we read everything.
3537 		 * When replacing, we need the replaced block.
3538 		 */
3539 		return 1;
3540 
3541 	if ((s->failed >= 1 && fdev[0]->toread) ||
3542 	    (s->failed >= 2 && fdev[1]->toread))
3543 		/* If we want to read from a failed device, then
3544 		 * we need to actually read every other device.
3545 		 */
3546 		return 1;
3547 
3548 	/* Sometimes neither read-modify-write nor reconstruct-write
3549 	 * cycles can work.  In those cases we read every block we
3550 	 * can.  Then the parity-update is certain to have enough to
3551 	 * work with.
3552 	 * This can only be a problem when we need to write something,
3553 	 * and some device has failed.  If either of those tests
3554 	 * fail we need look no further.
3555 	 */
3556 	if (!s->failed || !s->to_write)
3557 		return 0;
3558 
3559 	if (test_bit(R5_Insync, &dev->flags) &&
3560 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3561 		/* Pre-reads at not permitted until after short delay
3562 		 * to gather multiple requests.  However if this
3563 		 * device is no Insync, the block could only be computed
3564 		 * and there is no need to delay that.
3565 		 */
3566 		return 0;
3567 
3568 	for (i = 0; i < s->failed && i < 2; i++) {
3569 		if (fdev[i]->towrite &&
3570 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3571 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3572 			/* If we have a partial write to a failed
3573 			 * device, then we will need to reconstruct
3574 			 * the content of that device, so all other
3575 			 * devices must be read.
3576 			 */
3577 			return 1;
3578 	}
3579 
3580 	/* If we are forced to do a reconstruct-write, either because
3581 	 * the current RAID6 implementation only supports that, or
3582 	 * because parity cannot be trusted and we are currently
3583 	 * recovering it, there is extra need to be careful.
3584 	 * If one of the devices that we would need to read, because
3585 	 * it is not being overwritten (and maybe not written at all)
3586 	 * is missing/faulty, then we need to read everything we can.
3587 	 */
3588 	if (sh->raid_conf->level != 6 &&
3589 	    sh->sector < sh->raid_conf->mddev->recovery_cp)
3590 		/* reconstruct-write isn't being forced */
3591 		return 0;
3592 	for (i = 0; i < s->failed && i < 2; i++) {
3593 		if (s->failed_num[i] != sh->pd_idx &&
3594 		    s->failed_num[i] != sh->qd_idx &&
3595 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3596 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3597 			return 1;
3598 	}
3599 
3600 	return 0;
3601 }
3602 
3603 /* fetch_block - checks the given member device to see if its data needs
3604  * to be read or computed to satisfy a request.
3605  *
3606  * Returns 1 when no more member devices need to be checked, otherwise returns
3607  * 0 to tell the loop in handle_stripe_fill to continue
3608  */
3609 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3610 		       int disk_idx, int disks)
3611 {
3612 	struct r5dev *dev = &sh->dev[disk_idx];
3613 
3614 	/* is the data in this block needed, and can we get it? */
3615 	if (need_this_block(sh, s, disk_idx, disks)) {
3616 		/* we would like to get this block, possibly by computing it,
3617 		 * otherwise read it if the backing disk is insync
3618 		 */
3619 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3620 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
3621 		BUG_ON(sh->batch_head);
3622 
3623 		/*
3624 		 * In the raid6 case if the only non-uptodate disk is P
3625 		 * then we already trusted P to compute the other failed
3626 		 * drives. It is safe to compute rather than re-read P.
3627 		 * In other cases we only compute blocks from failed
3628 		 * devices, otherwise check/repair might fail to detect
3629 		 * a real inconsistency.
3630 		 */
3631 
3632 		if ((s->uptodate == disks - 1) &&
3633 		    ((sh->qd_idx >= 0 && sh->pd_idx == disk_idx) ||
3634 		    (s->failed && (disk_idx == s->failed_num[0] ||
3635 				   disk_idx == s->failed_num[1])))) {
3636 			/* have disk failed, and we're requested to fetch it;
3637 			 * do compute it
3638 			 */
3639 			pr_debug("Computing stripe %llu block %d\n",
3640 			       (unsigned long long)sh->sector, disk_idx);
3641 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3642 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3643 			set_bit(R5_Wantcompute, &dev->flags);
3644 			sh->ops.target = disk_idx;
3645 			sh->ops.target2 = -1; /* no 2nd target */
3646 			s->req_compute = 1;
3647 			/* Careful: from this point on 'uptodate' is in the eye
3648 			 * of raid_run_ops which services 'compute' operations
3649 			 * before writes. R5_Wantcompute flags a block that will
3650 			 * be R5_UPTODATE by the time it is needed for a
3651 			 * subsequent operation.
3652 			 */
3653 			s->uptodate++;
3654 			return 1;
3655 		} else if (s->uptodate == disks-2 && s->failed >= 2) {
3656 			/* Computing 2-failure is *very* expensive; only
3657 			 * do it if failed >= 2
3658 			 */
3659 			int other;
3660 			for (other = disks; other--; ) {
3661 				if (other == disk_idx)
3662 					continue;
3663 				if (!test_bit(R5_UPTODATE,
3664 				      &sh->dev[other].flags))
3665 					break;
3666 			}
3667 			BUG_ON(other < 0);
3668 			pr_debug("Computing stripe %llu blocks %d,%d\n",
3669 			       (unsigned long long)sh->sector,
3670 			       disk_idx, other);
3671 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3672 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3673 			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3674 			set_bit(R5_Wantcompute, &sh->dev[other].flags);
3675 			sh->ops.target = disk_idx;
3676 			sh->ops.target2 = other;
3677 			s->uptodate += 2;
3678 			s->req_compute = 1;
3679 			return 1;
3680 		} else if (test_bit(R5_Insync, &dev->flags)) {
3681 			set_bit(R5_LOCKED, &dev->flags);
3682 			set_bit(R5_Wantread, &dev->flags);
3683 			s->locked++;
3684 			pr_debug("Reading block %d (sync=%d)\n",
3685 				disk_idx, s->syncing);
3686 		}
3687 	}
3688 
3689 	return 0;
3690 }
3691 
3692 /**
3693  * handle_stripe_fill - read or compute data to satisfy pending requests.
3694  */
3695 static void handle_stripe_fill(struct stripe_head *sh,
3696 			       struct stripe_head_state *s,
3697 			       int disks)
3698 {
3699 	int i;
3700 
3701 	/* look for blocks to read/compute, skip this if a compute
3702 	 * is already in flight, or if the stripe contents are in the
3703 	 * midst of changing due to a write
3704 	 */
3705 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3706 	    !sh->reconstruct_state) {
3707 
3708 		/*
3709 		 * For degraded stripe with data in journal, do not handle
3710 		 * read requests yet, instead, flush the stripe to raid
3711 		 * disks first, this avoids handling complex rmw of write
3712 		 * back cache (prexor with orig_page, and then xor with
3713 		 * page) in the read path
3714 		 */
3715 		if (s->injournal && s->failed) {
3716 			if (test_bit(STRIPE_R5C_CACHING, &sh->state))
3717 				r5c_make_stripe_write_out(sh);
3718 			goto out;
3719 		}
3720 
3721 		for (i = disks; i--; )
3722 			if (fetch_block(sh, s, i, disks))
3723 				break;
3724 	}
3725 out:
3726 	set_bit(STRIPE_HANDLE, &sh->state);
3727 }
3728 
3729 static void break_stripe_batch_list(struct stripe_head *head_sh,
3730 				    unsigned long handle_flags);
3731 /* handle_stripe_clean_event
3732  * any written block on an uptodate or failed drive can be returned.
3733  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3734  * never LOCKED, so we don't need to test 'failed' directly.
3735  */
3736 static void handle_stripe_clean_event(struct r5conf *conf,
3737 	struct stripe_head *sh, int disks)
3738 {
3739 	int i;
3740 	struct r5dev *dev;
3741 	int discard_pending = 0;
3742 	struct stripe_head *head_sh = sh;
3743 	bool do_endio = false;
3744 
3745 	for (i = disks; i--; )
3746 		if (sh->dev[i].written) {
3747 			dev = &sh->dev[i];
3748 			if (!test_bit(R5_LOCKED, &dev->flags) &&
3749 			    (test_bit(R5_UPTODATE, &dev->flags) ||
3750 			     test_bit(R5_Discard, &dev->flags) ||
3751 			     test_bit(R5_SkipCopy, &dev->flags))) {
3752 				/* We can return any write requests */
3753 				struct bio *wbi, *wbi2;
3754 				pr_debug("Return write for disc %d\n", i);
3755 				if (test_and_clear_bit(R5_Discard, &dev->flags))
3756 					clear_bit(R5_UPTODATE, &dev->flags);
3757 				if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3758 					WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3759 				}
3760 				do_endio = true;
3761 
3762 returnbi:
3763 				dev->page = dev->orig_page;
3764 				wbi = dev->written;
3765 				dev->written = NULL;
3766 				while (wbi && wbi->bi_iter.bi_sector <
3767 					dev->sector + STRIPE_SECTORS) {
3768 					wbi2 = r5_next_bio(wbi, dev->sector);
3769 					md_write_end(conf->mddev);
3770 					bio_endio(wbi);
3771 					wbi = wbi2;
3772 				}
3773 				bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3774 						STRIPE_SECTORS,
3775 					 !test_bit(STRIPE_DEGRADED, &sh->state),
3776 						0);
3777 				if (head_sh->batch_head) {
3778 					sh = list_first_entry(&sh->batch_list,
3779 							      struct stripe_head,
3780 							      batch_list);
3781 					if (sh != head_sh) {
3782 						dev = &sh->dev[i];
3783 						goto returnbi;
3784 					}
3785 				}
3786 				sh = head_sh;
3787 				dev = &sh->dev[i];
3788 			} else if (test_bit(R5_Discard, &dev->flags))
3789 				discard_pending = 1;
3790 		}
3791 
3792 	log_stripe_write_finished(sh);
3793 
3794 	if (!discard_pending &&
3795 	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3796 		int hash;
3797 		clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3798 		clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3799 		if (sh->qd_idx >= 0) {
3800 			clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3801 			clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3802 		}
3803 		/* now that discard is done we can proceed with any sync */
3804 		clear_bit(STRIPE_DISCARD, &sh->state);
3805 		/*
3806 		 * SCSI discard will change some bio fields and the stripe has
3807 		 * no updated data, so remove it from hash list and the stripe
3808 		 * will be reinitialized
3809 		 */
3810 unhash:
3811 		hash = sh->hash_lock_index;
3812 		spin_lock_irq(conf->hash_locks + hash);
3813 		remove_hash(sh);
3814 		spin_unlock_irq(conf->hash_locks + hash);
3815 		if (head_sh->batch_head) {
3816 			sh = list_first_entry(&sh->batch_list,
3817 					      struct stripe_head, batch_list);
3818 			if (sh != head_sh)
3819 					goto unhash;
3820 		}
3821 		sh = head_sh;
3822 
3823 		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3824 			set_bit(STRIPE_HANDLE, &sh->state);
3825 
3826 	}
3827 
3828 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3829 		if (atomic_dec_and_test(&conf->pending_full_writes))
3830 			md_wakeup_thread(conf->mddev->thread);
3831 
3832 	if (head_sh->batch_head && do_endio)
3833 		break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3834 }
3835 
3836 /*
3837  * For RMW in write back cache, we need extra page in prexor to store the
3838  * old data. This page is stored in dev->orig_page.
3839  *
3840  * This function checks whether we have data for prexor. The exact logic
3841  * is:
3842  *       R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
3843  */
3844 static inline bool uptodate_for_rmw(struct r5dev *dev)
3845 {
3846 	return (test_bit(R5_UPTODATE, &dev->flags)) &&
3847 		(!test_bit(R5_InJournal, &dev->flags) ||
3848 		 test_bit(R5_OrigPageUPTDODATE, &dev->flags));
3849 }
3850 
3851 static int handle_stripe_dirtying(struct r5conf *conf,
3852 				  struct stripe_head *sh,
3853 				  struct stripe_head_state *s,
3854 				  int disks)
3855 {
3856 	int rmw = 0, rcw = 0, i;
3857 	sector_t recovery_cp = conf->mddev->recovery_cp;
3858 
3859 	/* Check whether resync is now happening or should start.
3860 	 * If yes, then the array is dirty (after unclean shutdown or
3861 	 * initial creation), so parity in some stripes might be inconsistent.
3862 	 * In this case, we need to always do reconstruct-write, to ensure
3863 	 * that in case of drive failure or read-error correction, we
3864 	 * generate correct data from the parity.
3865 	 */
3866 	if (conf->rmw_level == PARITY_DISABLE_RMW ||
3867 	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3868 	     s->failed == 0)) {
3869 		/* Calculate the real rcw later - for now make it
3870 		 * look like rcw is cheaper
3871 		 */
3872 		rcw = 1; rmw = 2;
3873 		pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3874 			 conf->rmw_level, (unsigned long long)recovery_cp,
3875 			 (unsigned long long)sh->sector);
3876 	} else for (i = disks; i--; ) {
3877 		/* would I have to read this buffer for read_modify_write */
3878 		struct r5dev *dev = &sh->dev[i];
3879 		if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
3880 		     i == sh->pd_idx || i == sh->qd_idx ||
3881 		     test_bit(R5_InJournal, &dev->flags)) &&
3882 		    !test_bit(R5_LOCKED, &dev->flags) &&
3883 		    !(uptodate_for_rmw(dev) ||
3884 		      test_bit(R5_Wantcompute, &dev->flags))) {
3885 			if (test_bit(R5_Insync, &dev->flags))
3886 				rmw++;
3887 			else
3888 				rmw += 2*disks;  /* cannot read it */
3889 		}
3890 		/* Would I have to read this buffer for reconstruct_write */
3891 		if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3892 		    i != sh->pd_idx && i != sh->qd_idx &&
3893 		    !test_bit(R5_LOCKED, &dev->flags) &&
3894 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
3895 		      test_bit(R5_Wantcompute, &dev->flags))) {
3896 			if (test_bit(R5_Insync, &dev->flags))
3897 				rcw++;
3898 			else
3899 				rcw += 2*disks;
3900 		}
3901 	}
3902 
3903 	pr_debug("for sector %llu state 0x%lx, rmw=%d rcw=%d\n",
3904 		 (unsigned long long)sh->sector, sh->state, rmw, rcw);
3905 	set_bit(STRIPE_HANDLE, &sh->state);
3906 	if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
3907 		/* prefer read-modify-write, but need to get some data */
3908 		if (conf->mddev->queue)
3909 			blk_add_trace_msg(conf->mddev->queue,
3910 					  "raid5 rmw %llu %d",
3911 					  (unsigned long long)sh->sector, rmw);
3912 		for (i = disks; i--; ) {
3913 			struct r5dev *dev = &sh->dev[i];
3914 			if (test_bit(R5_InJournal, &dev->flags) &&
3915 			    dev->page == dev->orig_page &&
3916 			    !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {
3917 				/* alloc page for prexor */
3918 				struct page *p = alloc_page(GFP_NOIO);
3919 
3920 				if (p) {
3921 					dev->orig_page = p;
3922 					continue;
3923 				}
3924 
3925 				/*
3926 				 * alloc_page() failed, try use
3927 				 * disk_info->extra_page
3928 				 */
3929 				if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,
3930 						      &conf->cache_state)) {
3931 					r5c_use_extra_page(sh);
3932 					break;
3933 				}
3934 
3935 				/* extra_page in use, add to delayed_list */
3936 				set_bit(STRIPE_DELAYED, &sh->state);
3937 				s->waiting_extra_page = 1;
3938 				return -EAGAIN;
3939 			}
3940 		}
3941 
3942 		for (i = disks; i--; ) {
3943 			struct r5dev *dev = &sh->dev[i];
3944 			if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
3945 			     i == sh->pd_idx || i == sh->qd_idx ||
3946 			     test_bit(R5_InJournal, &dev->flags)) &&
3947 			    !test_bit(R5_LOCKED, &dev->flags) &&
3948 			    !(uptodate_for_rmw(dev) ||
3949 			      test_bit(R5_Wantcompute, &dev->flags)) &&
3950 			    test_bit(R5_Insync, &dev->flags)) {
3951 				if (test_bit(STRIPE_PREREAD_ACTIVE,
3952 					     &sh->state)) {
3953 					pr_debug("Read_old block %d for r-m-w\n",
3954 						 i);
3955 					set_bit(R5_LOCKED, &dev->flags);
3956 					set_bit(R5_Wantread, &dev->flags);
3957 					s->locked++;
3958 				} else {
3959 					set_bit(STRIPE_DELAYED, &sh->state);
3960 					set_bit(STRIPE_HANDLE, &sh->state);
3961 				}
3962 			}
3963 		}
3964 	}
3965 	if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
3966 		/* want reconstruct write, but need to get some data */
3967 		int qread =0;
3968 		rcw = 0;
3969 		for (i = disks; i--; ) {
3970 			struct r5dev *dev = &sh->dev[i];
3971 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3972 			    i != sh->pd_idx && i != sh->qd_idx &&
3973 			    !test_bit(R5_LOCKED, &dev->flags) &&
3974 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
3975 			      test_bit(R5_Wantcompute, &dev->flags))) {
3976 				rcw++;
3977 				if (test_bit(R5_Insync, &dev->flags) &&
3978 				    test_bit(STRIPE_PREREAD_ACTIVE,
3979 					     &sh->state)) {
3980 					pr_debug("Read_old block "
3981 						"%d for Reconstruct\n", i);
3982 					set_bit(R5_LOCKED, &dev->flags);
3983 					set_bit(R5_Wantread, &dev->flags);
3984 					s->locked++;
3985 					qread++;
3986 				} else {
3987 					set_bit(STRIPE_DELAYED, &sh->state);
3988 					set_bit(STRIPE_HANDLE, &sh->state);
3989 				}
3990 			}
3991 		}
3992 		if (rcw && conf->mddev->queue)
3993 			blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3994 					  (unsigned long long)sh->sector,
3995 					  rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3996 	}
3997 
3998 	if (rcw > disks && rmw > disks &&
3999 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4000 		set_bit(STRIPE_DELAYED, &sh->state);
4001 
4002 	/* now if nothing is locked, and if we have enough data,
4003 	 * we can start a write request
4004 	 */
4005 	/* since handle_stripe can be called at any time we need to handle the
4006 	 * case where a compute block operation has been submitted and then a
4007 	 * subsequent call wants to start a write request.  raid_run_ops only
4008 	 * handles the case where compute block and reconstruct are requested
4009 	 * simultaneously.  If this is not the case then new writes need to be
4010 	 * held off until the compute completes.
4011 	 */
4012 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
4013 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
4014 	     !test_bit(STRIPE_BIT_DELAY, &sh->state)))
4015 		schedule_reconstruction(sh, s, rcw == 0, 0);
4016 	return 0;
4017 }
4018 
4019 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
4020 				struct stripe_head_state *s, int disks)
4021 {
4022 	struct r5dev *dev = NULL;
4023 
4024 	BUG_ON(sh->batch_head);
4025 	set_bit(STRIPE_HANDLE, &sh->state);
4026 
4027 	switch (sh->check_state) {
4028 	case check_state_idle:
4029 		/* start a new check operation if there are no failures */
4030 		if (s->failed == 0) {
4031 			BUG_ON(s->uptodate != disks);
4032 			sh->check_state = check_state_run;
4033 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
4034 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
4035 			s->uptodate--;
4036 			break;
4037 		}
4038 		dev = &sh->dev[s->failed_num[0]];
4039 		/* fall through */
4040 	case check_state_compute_result:
4041 		sh->check_state = check_state_idle;
4042 		if (!dev)
4043 			dev = &sh->dev[sh->pd_idx];
4044 
4045 		/* check that a write has not made the stripe insync */
4046 		if (test_bit(STRIPE_INSYNC, &sh->state))
4047 			break;
4048 
4049 		/* either failed parity check, or recovery is happening */
4050 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
4051 		BUG_ON(s->uptodate != disks);
4052 
4053 		set_bit(R5_LOCKED, &dev->flags);
4054 		s->locked++;
4055 		set_bit(R5_Wantwrite, &dev->flags);
4056 
4057 		clear_bit(STRIPE_DEGRADED, &sh->state);
4058 		set_bit(STRIPE_INSYNC, &sh->state);
4059 		break;
4060 	case check_state_run:
4061 		break; /* we will be called again upon completion */
4062 	case check_state_check_result:
4063 		sh->check_state = check_state_idle;
4064 
4065 		/* if a failure occurred during the check operation, leave
4066 		 * STRIPE_INSYNC not set and let the stripe be handled again
4067 		 */
4068 		if (s->failed)
4069 			break;
4070 
4071 		/* handle a successful check operation, if parity is correct
4072 		 * we are done.  Otherwise update the mismatch count and repair
4073 		 * parity if !MD_RECOVERY_CHECK
4074 		 */
4075 		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
4076 			/* parity is correct (on disc,
4077 			 * not in buffer any more)
4078 			 */
4079 			set_bit(STRIPE_INSYNC, &sh->state);
4080 		else {
4081 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
4082 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery)) {
4083 				/* don't try to repair!! */
4084 				set_bit(STRIPE_INSYNC, &sh->state);
4085 				pr_warn_ratelimited("%s: mismatch sector in range "
4086 						    "%llu-%llu\n", mdname(conf->mddev),
4087 						    (unsigned long long) sh->sector,
4088 						    (unsigned long long) sh->sector +
4089 						    STRIPE_SECTORS);
4090 			} else {
4091 				sh->check_state = check_state_compute_run;
4092 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4093 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4094 				set_bit(R5_Wantcompute,
4095 					&sh->dev[sh->pd_idx].flags);
4096 				sh->ops.target = sh->pd_idx;
4097 				sh->ops.target2 = -1;
4098 				s->uptodate++;
4099 			}
4100 		}
4101 		break;
4102 	case check_state_compute_run:
4103 		break;
4104 	default:
4105 		pr_err("%s: unknown check_state: %d sector: %llu\n",
4106 		       __func__, sh->check_state,
4107 		       (unsigned long long) sh->sector);
4108 		BUG();
4109 	}
4110 }
4111 
4112 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
4113 				  struct stripe_head_state *s,
4114 				  int disks)
4115 {
4116 	int pd_idx = sh->pd_idx;
4117 	int qd_idx = sh->qd_idx;
4118 	struct r5dev *dev;
4119 
4120 	BUG_ON(sh->batch_head);
4121 	set_bit(STRIPE_HANDLE, &sh->state);
4122 
4123 	BUG_ON(s->failed > 2);
4124 
4125 	/* Want to check and possibly repair P and Q.
4126 	 * However there could be one 'failed' device, in which
4127 	 * case we can only check one of them, possibly using the
4128 	 * other to generate missing data
4129 	 */
4130 
4131 	switch (sh->check_state) {
4132 	case check_state_idle:
4133 		/* start a new check operation if there are < 2 failures */
4134 		if (s->failed == s->q_failed) {
4135 			/* The only possible failed device holds Q, so it
4136 			 * makes sense to check P (If anything else were failed,
4137 			 * we would have used P to recreate it).
4138 			 */
4139 			sh->check_state = check_state_run;
4140 		}
4141 		if (!s->q_failed && s->failed < 2) {
4142 			/* Q is not failed, and we didn't use it to generate
4143 			 * anything, so it makes sense to check it
4144 			 */
4145 			if (sh->check_state == check_state_run)
4146 				sh->check_state = check_state_run_pq;
4147 			else
4148 				sh->check_state = check_state_run_q;
4149 		}
4150 
4151 		/* discard potentially stale zero_sum_result */
4152 		sh->ops.zero_sum_result = 0;
4153 
4154 		if (sh->check_state == check_state_run) {
4155 			/* async_xor_zero_sum destroys the contents of P */
4156 			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
4157 			s->uptodate--;
4158 		}
4159 		if (sh->check_state >= check_state_run &&
4160 		    sh->check_state <= check_state_run_pq) {
4161 			/* async_syndrome_zero_sum preserves P and Q, so
4162 			 * no need to mark them !uptodate here
4163 			 */
4164 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
4165 			break;
4166 		}
4167 
4168 		/* we have 2-disk failure */
4169 		BUG_ON(s->failed != 2);
4170 		/* fall through */
4171 	case check_state_compute_result:
4172 		sh->check_state = check_state_idle;
4173 
4174 		/* check that a write has not made the stripe insync */
4175 		if (test_bit(STRIPE_INSYNC, &sh->state))
4176 			break;
4177 
4178 		/* now write out any block on a failed drive,
4179 		 * or P or Q if they were recomputed
4180 		 */
4181 		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
4182 		if (s->failed == 2) {
4183 			dev = &sh->dev[s->failed_num[1]];
4184 			s->locked++;
4185 			set_bit(R5_LOCKED, &dev->flags);
4186 			set_bit(R5_Wantwrite, &dev->flags);
4187 		}
4188 		if (s->failed >= 1) {
4189 			dev = &sh->dev[s->failed_num[0]];
4190 			s->locked++;
4191 			set_bit(R5_LOCKED, &dev->flags);
4192 			set_bit(R5_Wantwrite, &dev->flags);
4193 		}
4194 		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4195 			dev = &sh->dev[pd_idx];
4196 			s->locked++;
4197 			set_bit(R5_LOCKED, &dev->flags);
4198 			set_bit(R5_Wantwrite, &dev->flags);
4199 		}
4200 		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4201 			dev = &sh->dev[qd_idx];
4202 			s->locked++;
4203 			set_bit(R5_LOCKED, &dev->flags);
4204 			set_bit(R5_Wantwrite, &dev->flags);
4205 		}
4206 		clear_bit(STRIPE_DEGRADED, &sh->state);
4207 
4208 		set_bit(STRIPE_INSYNC, &sh->state);
4209 		break;
4210 	case check_state_run:
4211 	case check_state_run_q:
4212 	case check_state_run_pq:
4213 		break; /* we will be called again upon completion */
4214 	case check_state_check_result:
4215 		sh->check_state = check_state_idle;
4216 
4217 		/* handle a successful check operation, if parity is correct
4218 		 * we are done.  Otherwise update the mismatch count and repair
4219 		 * parity if !MD_RECOVERY_CHECK
4220 		 */
4221 		if (sh->ops.zero_sum_result == 0) {
4222 			/* both parities are correct */
4223 			if (!s->failed)
4224 				set_bit(STRIPE_INSYNC, &sh->state);
4225 			else {
4226 				/* in contrast to the raid5 case we can validate
4227 				 * parity, but still have a failure to write
4228 				 * back
4229 				 */
4230 				sh->check_state = check_state_compute_result;
4231 				/* Returning at this point means that we may go
4232 				 * off and bring p and/or q uptodate again so
4233 				 * we make sure to check zero_sum_result again
4234 				 * to verify if p or q need writeback
4235 				 */
4236 			}
4237 		} else {
4238 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
4239 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery)) {
4240 				/* don't try to repair!! */
4241 				set_bit(STRIPE_INSYNC, &sh->state);
4242 				pr_warn_ratelimited("%s: mismatch sector in range "
4243 						    "%llu-%llu\n", mdname(conf->mddev),
4244 						    (unsigned long long) sh->sector,
4245 						    (unsigned long long) sh->sector +
4246 						    STRIPE_SECTORS);
4247 			} else {
4248 				int *target = &sh->ops.target;
4249 
4250 				sh->ops.target = -1;
4251 				sh->ops.target2 = -1;
4252 				sh->check_state = check_state_compute_run;
4253 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4254 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4255 				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4256 					set_bit(R5_Wantcompute,
4257 						&sh->dev[pd_idx].flags);
4258 					*target = pd_idx;
4259 					target = &sh->ops.target2;
4260 					s->uptodate++;
4261 				}
4262 				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4263 					set_bit(R5_Wantcompute,
4264 						&sh->dev[qd_idx].flags);
4265 					*target = qd_idx;
4266 					s->uptodate++;
4267 				}
4268 			}
4269 		}
4270 		break;
4271 	case check_state_compute_run:
4272 		break;
4273 	default:
4274 		pr_warn("%s: unknown check_state: %d sector: %llu\n",
4275 			__func__, sh->check_state,
4276 			(unsigned long long) sh->sector);
4277 		BUG();
4278 	}
4279 }
4280 
4281 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
4282 {
4283 	int i;
4284 
4285 	/* We have read all the blocks in this stripe and now we need to
4286 	 * copy some of them into a target stripe for expand.
4287 	 */
4288 	struct dma_async_tx_descriptor *tx = NULL;
4289 	BUG_ON(sh->batch_head);
4290 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4291 	for (i = 0; i < sh->disks; i++)
4292 		if (i != sh->pd_idx && i != sh->qd_idx) {
4293 			int dd_idx, j;
4294 			struct stripe_head *sh2;
4295 			struct async_submit_ctl submit;
4296 
4297 			sector_t bn = raid5_compute_blocknr(sh, i, 1);
4298 			sector_t s = raid5_compute_sector(conf, bn, 0,
4299 							  &dd_idx, NULL);
4300 			sh2 = raid5_get_active_stripe(conf, s, 0, 1, 1);
4301 			if (sh2 == NULL)
4302 				/* so far only the early blocks of this stripe
4303 				 * have been requested.  When later blocks
4304 				 * get requested, we will try again
4305 				 */
4306 				continue;
4307 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
4308 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
4309 				/* must have already done this block */
4310 				raid5_release_stripe(sh2);
4311 				continue;
4312 			}
4313 
4314 			/* place all the copies on one channel */
4315 			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4316 			tx = async_memcpy(sh2->dev[dd_idx].page,
4317 					  sh->dev[i].page, 0, 0, STRIPE_SIZE,
4318 					  &submit);
4319 
4320 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4321 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4322 			for (j = 0; j < conf->raid_disks; j++)
4323 				if (j != sh2->pd_idx &&
4324 				    j != sh2->qd_idx &&
4325 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
4326 					break;
4327 			if (j == conf->raid_disks) {
4328 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
4329 				set_bit(STRIPE_HANDLE, &sh2->state);
4330 			}
4331 			raid5_release_stripe(sh2);
4332 
4333 		}
4334 	/* done submitting copies, wait for them to complete */
4335 	async_tx_quiesce(&tx);
4336 }
4337 
4338 /*
4339  * handle_stripe - do things to a stripe.
4340  *
4341  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4342  * state of various bits to see what needs to be done.
4343  * Possible results:
4344  *    return some read requests which now have data
4345  *    return some write requests which are safely on storage
4346  *    schedule a read on some buffers
4347  *    schedule a write of some buffers
4348  *    return confirmation of parity correctness
4349  *
4350  */
4351 
4352 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4353 {
4354 	struct r5conf *conf = sh->raid_conf;
4355 	int disks = sh->disks;
4356 	struct r5dev *dev;
4357 	int i;
4358 	int do_recovery = 0;
4359 
4360 	memset(s, 0, sizeof(*s));
4361 
4362 	s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4363 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4364 	s->failed_num[0] = -1;
4365 	s->failed_num[1] = -1;
4366 	s->log_failed = r5l_log_disk_error(conf);
4367 
4368 	/* Now to look around and see what can be done */
4369 	rcu_read_lock();
4370 	for (i=disks; i--; ) {
4371 		struct md_rdev *rdev;
4372 		sector_t first_bad;
4373 		int bad_sectors;
4374 		int is_bad = 0;
4375 
4376 		dev = &sh->dev[i];
4377 
4378 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4379 			 i, dev->flags,
4380 			 dev->toread, dev->towrite, dev->written);
4381 		/* maybe we can reply to a read
4382 		 *
4383 		 * new wantfill requests are only permitted while
4384 		 * ops_complete_biofill is guaranteed to be inactive
4385 		 */
4386 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4387 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4388 			set_bit(R5_Wantfill, &dev->flags);
4389 
4390 		/* now count some things */
4391 		if (test_bit(R5_LOCKED, &dev->flags))
4392 			s->locked++;
4393 		if (test_bit(R5_UPTODATE, &dev->flags))
4394 			s->uptodate++;
4395 		if (test_bit(R5_Wantcompute, &dev->flags)) {
4396 			s->compute++;
4397 			BUG_ON(s->compute > 2);
4398 		}
4399 
4400 		if (test_bit(R5_Wantfill, &dev->flags))
4401 			s->to_fill++;
4402 		else if (dev->toread)
4403 			s->to_read++;
4404 		if (dev->towrite) {
4405 			s->to_write++;
4406 			if (!test_bit(R5_OVERWRITE, &dev->flags))
4407 				s->non_overwrite++;
4408 		}
4409 		if (dev->written)
4410 			s->written++;
4411 		/* Prefer to use the replacement for reads, but only
4412 		 * if it is recovered enough and has no bad blocks.
4413 		 */
4414 		rdev = rcu_dereference(conf->disks[i].replacement);
4415 		if (rdev && !test_bit(Faulty, &rdev->flags) &&
4416 		    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4417 		    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4418 				 &first_bad, &bad_sectors))
4419 			set_bit(R5_ReadRepl, &dev->flags);
4420 		else {
4421 			if (rdev && !test_bit(Faulty, &rdev->flags))
4422 				set_bit(R5_NeedReplace, &dev->flags);
4423 			else
4424 				clear_bit(R5_NeedReplace, &dev->flags);
4425 			rdev = rcu_dereference(conf->disks[i].rdev);
4426 			clear_bit(R5_ReadRepl, &dev->flags);
4427 		}
4428 		if (rdev && test_bit(Faulty, &rdev->flags))
4429 			rdev = NULL;
4430 		if (rdev) {
4431 			is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4432 					     &first_bad, &bad_sectors);
4433 			if (s->blocked_rdev == NULL
4434 			    && (test_bit(Blocked, &rdev->flags)
4435 				|| is_bad < 0)) {
4436 				if (is_bad < 0)
4437 					set_bit(BlockedBadBlocks,
4438 						&rdev->flags);
4439 				s->blocked_rdev = rdev;
4440 				atomic_inc(&rdev->nr_pending);
4441 			}
4442 		}
4443 		clear_bit(R5_Insync, &dev->flags);
4444 		if (!rdev)
4445 			/* Not in-sync */;
4446 		else if (is_bad) {
4447 			/* also not in-sync */
4448 			if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4449 			    test_bit(R5_UPTODATE, &dev->flags)) {
4450 				/* treat as in-sync, but with a read error
4451 				 * which we can now try to correct
4452 				 */
4453 				set_bit(R5_Insync, &dev->flags);
4454 				set_bit(R5_ReadError, &dev->flags);
4455 			}
4456 		} else if (test_bit(In_sync, &rdev->flags))
4457 			set_bit(R5_Insync, &dev->flags);
4458 		else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4459 			/* in sync if before recovery_offset */
4460 			set_bit(R5_Insync, &dev->flags);
4461 		else if (test_bit(R5_UPTODATE, &dev->flags) &&
4462 			 test_bit(R5_Expanded, &dev->flags))
4463 			/* If we've reshaped into here, we assume it is Insync.
4464 			 * We will shortly update recovery_offset to make
4465 			 * it official.
4466 			 */
4467 			set_bit(R5_Insync, &dev->flags);
4468 
4469 		if (test_bit(R5_WriteError, &dev->flags)) {
4470 			/* This flag does not apply to '.replacement'
4471 			 * only to .rdev, so make sure to check that*/
4472 			struct md_rdev *rdev2 = rcu_dereference(
4473 				conf->disks[i].rdev);
4474 			if (rdev2 == rdev)
4475 				clear_bit(R5_Insync, &dev->flags);
4476 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4477 				s->handle_bad_blocks = 1;
4478 				atomic_inc(&rdev2->nr_pending);
4479 			} else
4480 				clear_bit(R5_WriteError, &dev->flags);
4481 		}
4482 		if (test_bit(R5_MadeGood, &dev->flags)) {
4483 			/* This flag does not apply to '.replacement'
4484 			 * only to .rdev, so make sure to check that*/
4485 			struct md_rdev *rdev2 = rcu_dereference(
4486 				conf->disks[i].rdev);
4487 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4488 				s->handle_bad_blocks = 1;
4489 				atomic_inc(&rdev2->nr_pending);
4490 			} else
4491 				clear_bit(R5_MadeGood, &dev->flags);
4492 		}
4493 		if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4494 			struct md_rdev *rdev2 = rcu_dereference(
4495 				conf->disks[i].replacement);
4496 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4497 				s->handle_bad_blocks = 1;
4498 				atomic_inc(&rdev2->nr_pending);
4499 			} else
4500 				clear_bit(R5_MadeGoodRepl, &dev->flags);
4501 		}
4502 		if (!test_bit(R5_Insync, &dev->flags)) {
4503 			/* The ReadError flag will just be confusing now */
4504 			clear_bit(R5_ReadError, &dev->flags);
4505 			clear_bit(R5_ReWrite, &dev->flags);
4506 		}
4507 		if (test_bit(R5_ReadError, &dev->flags))
4508 			clear_bit(R5_Insync, &dev->flags);
4509 		if (!test_bit(R5_Insync, &dev->flags)) {
4510 			if (s->failed < 2)
4511 				s->failed_num[s->failed] = i;
4512 			s->failed++;
4513 			if (rdev && !test_bit(Faulty, &rdev->flags))
4514 				do_recovery = 1;
4515 		}
4516 
4517 		if (test_bit(R5_InJournal, &dev->flags))
4518 			s->injournal++;
4519 		if (test_bit(R5_InJournal, &dev->flags) && dev->written)
4520 			s->just_cached++;
4521 	}
4522 	if (test_bit(STRIPE_SYNCING, &sh->state)) {
4523 		/* If there is a failed device being replaced,
4524 		 *     we must be recovering.
4525 		 * else if we are after recovery_cp, we must be syncing
4526 		 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4527 		 * else we can only be replacing
4528 		 * sync and recovery both need to read all devices, and so
4529 		 * use the same flag.
4530 		 */
4531 		if (do_recovery ||
4532 		    sh->sector >= conf->mddev->recovery_cp ||
4533 		    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4534 			s->syncing = 1;
4535 		else
4536 			s->replacing = 1;
4537 	}
4538 	rcu_read_unlock();
4539 }
4540 
4541 static int clear_batch_ready(struct stripe_head *sh)
4542 {
4543 	/* Return '1' if this is a member of batch, or
4544 	 * '0' if it is a lone stripe or a head which can now be
4545 	 * handled.
4546 	 */
4547 	struct stripe_head *tmp;
4548 	if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4549 		return (sh->batch_head && sh->batch_head != sh);
4550 	spin_lock(&sh->stripe_lock);
4551 	if (!sh->batch_head) {
4552 		spin_unlock(&sh->stripe_lock);
4553 		return 0;
4554 	}
4555 
4556 	/*
4557 	 * this stripe could be added to a batch list before we check
4558 	 * BATCH_READY, skips it
4559 	 */
4560 	if (sh->batch_head != sh) {
4561 		spin_unlock(&sh->stripe_lock);
4562 		return 1;
4563 	}
4564 	spin_lock(&sh->batch_lock);
4565 	list_for_each_entry(tmp, &sh->batch_list, batch_list)
4566 		clear_bit(STRIPE_BATCH_READY, &tmp->state);
4567 	spin_unlock(&sh->batch_lock);
4568 	spin_unlock(&sh->stripe_lock);
4569 
4570 	/*
4571 	 * BATCH_READY is cleared, no new stripes can be added.
4572 	 * batch_list can be accessed without lock
4573 	 */
4574 	return 0;
4575 }
4576 
4577 static void break_stripe_batch_list(struct stripe_head *head_sh,
4578 				    unsigned long handle_flags)
4579 {
4580 	struct stripe_head *sh, *next;
4581 	int i;
4582 	int do_wakeup = 0;
4583 
4584 	list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4585 
4586 		list_del_init(&sh->batch_list);
4587 
4588 		WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4589 					  (1 << STRIPE_SYNCING) |
4590 					  (1 << STRIPE_REPLACED) |
4591 					  (1 << STRIPE_DELAYED) |
4592 					  (1 << STRIPE_BIT_DELAY) |
4593 					  (1 << STRIPE_FULL_WRITE) |
4594 					  (1 << STRIPE_BIOFILL_RUN) |
4595 					  (1 << STRIPE_COMPUTE_RUN)  |
4596 					  (1 << STRIPE_OPS_REQ_PENDING) |
4597 					  (1 << STRIPE_DISCARD) |
4598 					  (1 << STRIPE_BATCH_READY) |
4599 					  (1 << STRIPE_BATCH_ERR) |
4600 					  (1 << STRIPE_BITMAP_PENDING)),
4601 			"stripe state: %lx\n", sh->state);
4602 		WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4603 					      (1 << STRIPE_REPLACED)),
4604 			"head stripe state: %lx\n", head_sh->state);
4605 
4606 		set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4607 					    (1 << STRIPE_PREREAD_ACTIVE) |
4608 					    (1 << STRIPE_DEGRADED) |
4609 					    (1 << STRIPE_ON_UNPLUG_LIST)),
4610 			      head_sh->state & (1 << STRIPE_INSYNC));
4611 
4612 		sh->check_state = head_sh->check_state;
4613 		sh->reconstruct_state = head_sh->reconstruct_state;
4614 		for (i = 0; i < sh->disks; i++) {
4615 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4616 				do_wakeup = 1;
4617 			sh->dev[i].flags = head_sh->dev[i].flags &
4618 				(~((1 << R5_WriteError) | (1 << R5_Overlap)));
4619 		}
4620 		spin_lock_irq(&sh->stripe_lock);
4621 		sh->batch_head = NULL;
4622 		spin_unlock_irq(&sh->stripe_lock);
4623 		if (handle_flags == 0 ||
4624 		    sh->state & handle_flags)
4625 			set_bit(STRIPE_HANDLE, &sh->state);
4626 		raid5_release_stripe(sh);
4627 	}
4628 	spin_lock_irq(&head_sh->stripe_lock);
4629 	head_sh->batch_head = NULL;
4630 	spin_unlock_irq(&head_sh->stripe_lock);
4631 	for (i = 0; i < head_sh->disks; i++)
4632 		if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4633 			do_wakeup = 1;
4634 	if (head_sh->state & handle_flags)
4635 		set_bit(STRIPE_HANDLE, &head_sh->state);
4636 
4637 	if (do_wakeup)
4638 		wake_up(&head_sh->raid_conf->wait_for_overlap);
4639 }
4640 
4641 static void handle_stripe(struct stripe_head *sh)
4642 {
4643 	struct stripe_head_state s;
4644 	struct r5conf *conf = sh->raid_conf;
4645 	int i;
4646 	int prexor;
4647 	int disks = sh->disks;
4648 	struct r5dev *pdev, *qdev;
4649 
4650 	clear_bit(STRIPE_HANDLE, &sh->state);
4651 	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4652 		/* already being handled, ensure it gets handled
4653 		 * again when current action finishes */
4654 		set_bit(STRIPE_HANDLE, &sh->state);
4655 		return;
4656 	}
4657 
4658 	if (clear_batch_ready(sh) ) {
4659 		clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4660 		return;
4661 	}
4662 
4663 	if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4664 		break_stripe_batch_list(sh, 0);
4665 
4666 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4667 		spin_lock(&sh->stripe_lock);
4668 		/*
4669 		 * Cannot process 'sync' concurrently with 'discard'.
4670 		 * Flush data in r5cache before 'sync'.
4671 		 */
4672 		if (!test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) &&
4673 		    !test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state) &&
4674 		    !test_bit(STRIPE_DISCARD, &sh->state) &&
4675 		    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4676 			set_bit(STRIPE_SYNCING, &sh->state);
4677 			clear_bit(STRIPE_INSYNC, &sh->state);
4678 			clear_bit(STRIPE_REPLACED, &sh->state);
4679 		}
4680 		spin_unlock(&sh->stripe_lock);
4681 	}
4682 	clear_bit(STRIPE_DELAYED, &sh->state);
4683 
4684 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4685 		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4686 	       (unsigned long long)sh->sector, sh->state,
4687 	       atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4688 	       sh->check_state, sh->reconstruct_state);
4689 
4690 	analyse_stripe(sh, &s);
4691 
4692 	if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
4693 		goto finish;
4694 
4695 	if (s.handle_bad_blocks ||
4696 	    test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) {
4697 		set_bit(STRIPE_HANDLE, &sh->state);
4698 		goto finish;
4699 	}
4700 
4701 	if (unlikely(s.blocked_rdev)) {
4702 		if (s.syncing || s.expanding || s.expanded ||
4703 		    s.replacing || s.to_write || s.written) {
4704 			set_bit(STRIPE_HANDLE, &sh->state);
4705 			goto finish;
4706 		}
4707 		/* There is nothing for the blocked_rdev to block */
4708 		rdev_dec_pending(s.blocked_rdev, conf->mddev);
4709 		s.blocked_rdev = NULL;
4710 	}
4711 
4712 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4713 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4714 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4715 	}
4716 
4717 	pr_debug("locked=%d uptodate=%d to_read=%d"
4718 	       " to_write=%d failed=%d failed_num=%d,%d\n",
4719 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4720 	       s.failed_num[0], s.failed_num[1]);
4721 	/*
4722 	 * check if the array has lost more than max_degraded devices and,
4723 	 * if so, some requests might need to be failed.
4724 	 *
4725 	 * When journal device failed (log_failed), we will only process
4726 	 * the stripe if there is data need write to raid disks
4727 	 */
4728 	if (s.failed > conf->max_degraded ||
4729 	    (s.log_failed && s.injournal == 0)) {
4730 		sh->check_state = 0;
4731 		sh->reconstruct_state = 0;
4732 		break_stripe_batch_list(sh, 0);
4733 		if (s.to_read+s.to_write+s.written)
4734 			handle_failed_stripe(conf, sh, &s, disks);
4735 		if (s.syncing + s.replacing)
4736 			handle_failed_sync(conf, sh, &s);
4737 	}
4738 
4739 	/* Now we check to see if any write operations have recently
4740 	 * completed
4741 	 */
4742 	prexor = 0;
4743 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4744 		prexor = 1;
4745 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
4746 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4747 		sh->reconstruct_state = reconstruct_state_idle;
4748 
4749 		/* All the 'written' buffers and the parity block are ready to
4750 		 * be written back to disk
4751 		 */
4752 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4753 		       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4754 		BUG_ON(sh->qd_idx >= 0 &&
4755 		       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4756 		       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4757 		for (i = disks; i--; ) {
4758 			struct r5dev *dev = &sh->dev[i];
4759 			if (test_bit(R5_LOCKED, &dev->flags) &&
4760 				(i == sh->pd_idx || i == sh->qd_idx ||
4761 				 dev->written || test_bit(R5_InJournal,
4762 							  &dev->flags))) {
4763 				pr_debug("Writing block %d\n", i);
4764 				set_bit(R5_Wantwrite, &dev->flags);
4765 				if (prexor)
4766 					continue;
4767 				if (s.failed > 1)
4768 					continue;
4769 				if (!test_bit(R5_Insync, &dev->flags) ||
4770 				    ((i == sh->pd_idx || i == sh->qd_idx)  &&
4771 				     s.failed == 0))
4772 					set_bit(STRIPE_INSYNC, &sh->state);
4773 			}
4774 		}
4775 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4776 			s.dec_preread_active = 1;
4777 	}
4778 
4779 	/*
4780 	 * might be able to return some write requests if the parity blocks
4781 	 * are safe, or on a failed drive
4782 	 */
4783 	pdev = &sh->dev[sh->pd_idx];
4784 	s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4785 		|| (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4786 	qdev = &sh->dev[sh->qd_idx];
4787 	s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4788 		|| (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4789 		|| conf->level < 6;
4790 
4791 	if (s.written &&
4792 	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4793 			     && !test_bit(R5_LOCKED, &pdev->flags)
4794 			     && (test_bit(R5_UPTODATE, &pdev->flags) ||
4795 				 test_bit(R5_Discard, &pdev->flags))))) &&
4796 	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4797 			     && !test_bit(R5_LOCKED, &qdev->flags)
4798 			     && (test_bit(R5_UPTODATE, &qdev->flags) ||
4799 				 test_bit(R5_Discard, &qdev->flags))))))
4800 		handle_stripe_clean_event(conf, sh, disks);
4801 
4802 	if (s.just_cached)
4803 		r5c_handle_cached_data_endio(conf, sh, disks);
4804 	log_stripe_write_finished(sh);
4805 
4806 	/* Now we might consider reading some blocks, either to check/generate
4807 	 * parity, or to satisfy requests
4808 	 * or to load a block that is being partially written.
4809 	 */
4810 	if (s.to_read || s.non_overwrite
4811 	    || (conf->level == 6 && s.to_write && s.failed)
4812 	    || (s.syncing && (s.uptodate + s.compute < disks))
4813 	    || s.replacing
4814 	    || s.expanding)
4815 		handle_stripe_fill(sh, &s, disks);
4816 
4817 	/*
4818 	 * When the stripe finishes full journal write cycle (write to journal
4819 	 * and raid disk), this is the clean up procedure so it is ready for
4820 	 * next operation.
4821 	 */
4822 	r5c_finish_stripe_write_out(conf, sh, &s);
4823 
4824 	/*
4825 	 * Now to consider new write requests, cache write back and what else,
4826 	 * if anything should be read.  We do not handle new writes when:
4827 	 * 1/ A 'write' operation (copy+xor) is already in flight.
4828 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
4829 	 *    block.
4830 	 * 3/ A r5c cache log write is in flight.
4831 	 */
4832 
4833 	if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
4834 		if (!r5c_is_writeback(conf->log)) {
4835 			if (s.to_write)
4836 				handle_stripe_dirtying(conf, sh, &s, disks);
4837 		} else { /* write back cache */
4838 			int ret = 0;
4839 
4840 			/* First, try handle writes in caching phase */
4841 			if (s.to_write)
4842 				ret = r5c_try_caching_write(conf, sh, &s,
4843 							    disks);
4844 			/*
4845 			 * If caching phase failed: ret == -EAGAIN
4846 			 *    OR
4847 			 * stripe under reclaim: !caching && injournal
4848 			 *
4849 			 * fall back to handle_stripe_dirtying()
4850 			 */
4851 			if (ret == -EAGAIN ||
4852 			    /* stripe under reclaim: !caching && injournal */
4853 			    (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
4854 			     s.injournal > 0)) {
4855 				ret = handle_stripe_dirtying(conf, sh, &s,
4856 							     disks);
4857 				if (ret == -EAGAIN)
4858 					goto finish;
4859 			}
4860 		}
4861 	}
4862 
4863 	/* maybe we need to check and possibly fix the parity for this stripe
4864 	 * Any reads will already have been scheduled, so we just see if enough
4865 	 * data is available.  The parity check is held off while parity
4866 	 * dependent operations are in flight.
4867 	 */
4868 	if (sh->check_state ||
4869 	    (s.syncing && s.locked == 0 &&
4870 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4871 	     !test_bit(STRIPE_INSYNC, &sh->state))) {
4872 		if (conf->level == 6)
4873 			handle_parity_checks6(conf, sh, &s, disks);
4874 		else
4875 			handle_parity_checks5(conf, sh, &s, disks);
4876 	}
4877 
4878 	if ((s.replacing || s.syncing) && s.locked == 0
4879 	    && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4880 	    && !test_bit(STRIPE_REPLACED, &sh->state)) {
4881 		/* Write out to replacement devices where possible */
4882 		for (i = 0; i < conf->raid_disks; i++)
4883 			if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4884 				WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4885 				set_bit(R5_WantReplace, &sh->dev[i].flags);
4886 				set_bit(R5_LOCKED, &sh->dev[i].flags);
4887 				s.locked++;
4888 			}
4889 		if (s.replacing)
4890 			set_bit(STRIPE_INSYNC, &sh->state);
4891 		set_bit(STRIPE_REPLACED, &sh->state);
4892 	}
4893 	if ((s.syncing || s.replacing) && s.locked == 0 &&
4894 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4895 	    test_bit(STRIPE_INSYNC, &sh->state)) {
4896 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4897 		clear_bit(STRIPE_SYNCING, &sh->state);
4898 		if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4899 			wake_up(&conf->wait_for_overlap);
4900 	}
4901 
4902 	/* If the failed drives are just a ReadError, then we might need
4903 	 * to progress the repair/check process
4904 	 */
4905 	if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4906 		for (i = 0; i < s.failed; i++) {
4907 			struct r5dev *dev = &sh->dev[s.failed_num[i]];
4908 			if (test_bit(R5_ReadError, &dev->flags)
4909 			    && !test_bit(R5_LOCKED, &dev->flags)
4910 			    && test_bit(R5_UPTODATE, &dev->flags)
4911 				) {
4912 				if (!test_bit(R5_ReWrite, &dev->flags)) {
4913 					set_bit(R5_Wantwrite, &dev->flags);
4914 					set_bit(R5_ReWrite, &dev->flags);
4915 					set_bit(R5_LOCKED, &dev->flags);
4916 					s.locked++;
4917 				} else {
4918 					/* let's read it back */
4919 					set_bit(R5_Wantread, &dev->flags);
4920 					set_bit(R5_LOCKED, &dev->flags);
4921 					s.locked++;
4922 				}
4923 			}
4924 		}
4925 
4926 	/* Finish reconstruct operations initiated by the expansion process */
4927 	if (sh->reconstruct_state == reconstruct_state_result) {
4928 		struct stripe_head *sh_src
4929 			= raid5_get_active_stripe(conf, sh->sector, 1, 1, 1);
4930 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4931 			/* sh cannot be written until sh_src has been read.
4932 			 * so arrange for sh to be delayed a little
4933 			 */
4934 			set_bit(STRIPE_DELAYED, &sh->state);
4935 			set_bit(STRIPE_HANDLE, &sh->state);
4936 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4937 					      &sh_src->state))
4938 				atomic_inc(&conf->preread_active_stripes);
4939 			raid5_release_stripe(sh_src);
4940 			goto finish;
4941 		}
4942 		if (sh_src)
4943 			raid5_release_stripe(sh_src);
4944 
4945 		sh->reconstruct_state = reconstruct_state_idle;
4946 		clear_bit(STRIPE_EXPANDING, &sh->state);
4947 		for (i = conf->raid_disks; i--; ) {
4948 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
4949 			set_bit(R5_LOCKED, &sh->dev[i].flags);
4950 			s.locked++;
4951 		}
4952 	}
4953 
4954 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4955 	    !sh->reconstruct_state) {
4956 		/* Need to write out all blocks after computing parity */
4957 		sh->disks = conf->raid_disks;
4958 		stripe_set_idx(sh->sector, conf, 0, sh);
4959 		schedule_reconstruction(sh, &s, 1, 1);
4960 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4961 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
4962 		atomic_dec(&conf->reshape_stripes);
4963 		wake_up(&conf->wait_for_overlap);
4964 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4965 	}
4966 
4967 	if (s.expanding && s.locked == 0 &&
4968 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4969 		handle_stripe_expansion(conf, sh);
4970 
4971 finish:
4972 	/* wait for this device to become unblocked */
4973 	if (unlikely(s.blocked_rdev)) {
4974 		if (conf->mddev->external)
4975 			md_wait_for_blocked_rdev(s.blocked_rdev,
4976 						 conf->mddev);
4977 		else
4978 			/* Internal metadata will immediately
4979 			 * be written by raid5d, so we don't
4980 			 * need to wait here.
4981 			 */
4982 			rdev_dec_pending(s.blocked_rdev,
4983 					 conf->mddev);
4984 	}
4985 
4986 	if (s.handle_bad_blocks)
4987 		for (i = disks; i--; ) {
4988 			struct md_rdev *rdev;
4989 			struct r5dev *dev = &sh->dev[i];
4990 			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4991 				/* We own a safe reference to the rdev */
4992 				rdev = conf->disks[i].rdev;
4993 				if (!rdev_set_badblocks(rdev, sh->sector,
4994 							STRIPE_SECTORS, 0))
4995 					md_error(conf->mddev, rdev);
4996 				rdev_dec_pending(rdev, conf->mddev);
4997 			}
4998 			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4999 				rdev = conf->disks[i].rdev;
5000 				rdev_clear_badblocks(rdev, sh->sector,
5001 						     STRIPE_SECTORS, 0);
5002 				rdev_dec_pending(rdev, conf->mddev);
5003 			}
5004 			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
5005 				rdev = conf->disks[i].replacement;
5006 				if (!rdev)
5007 					/* rdev have been moved down */
5008 					rdev = conf->disks[i].rdev;
5009 				rdev_clear_badblocks(rdev, sh->sector,
5010 						     STRIPE_SECTORS, 0);
5011 				rdev_dec_pending(rdev, conf->mddev);
5012 			}
5013 		}
5014 
5015 	if (s.ops_request)
5016 		raid_run_ops(sh, s.ops_request);
5017 
5018 	ops_run_io(sh, &s);
5019 
5020 	if (s.dec_preread_active) {
5021 		/* We delay this until after ops_run_io so that if make_request
5022 		 * is waiting on a flush, it won't continue until the writes
5023 		 * have actually been submitted.
5024 		 */
5025 		atomic_dec(&conf->preread_active_stripes);
5026 		if (atomic_read(&conf->preread_active_stripes) <
5027 		    IO_THRESHOLD)
5028 			md_wakeup_thread(conf->mddev->thread);
5029 	}
5030 
5031 	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
5032 }
5033 
5034 static void raid5_activate_delayed(struct r5conf *conf)
5035 {
5036 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
5037 		while (!list_empty(&conf->delayed_list)) {
5038 			struct list_head *l = conf->delayed_list.next;
5039 			struct stripe_head *sh;
5040 			sh = list_entry(l, struct stripe_head, lru);
5041 			list_del_init(l);
5042 			clear_bit(STRIPE_DELAYED, &sh->state);
5043 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5044 				atomic_inc(&conf->preread_active_stripes);
5045 			list_add_tail(&sh->lru, &conf->hold_list);
5046 			raid5_wakeup_stripe_thread(sh);
5047 		}
5048 	}
5049 }
5050 
5051 static void activate_bit_delay(struct r5conf *conf,
5052 	struct list_head *temp_inactive_list)
5053 {
5054 	/* device_lock is held */
5055 	struct list_head head;
5056 	list_add(&head, &conf->bitmap_list);
5057 	list_del_init(&conf->bitmap_list);
5058 	while (!list_empty(&head)) {
5059 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
5060 		int hash;
5061 		list_del_init(&sh->lru);
5062 		atomic_inc(&sh->count);
5063 		hash = sh->hash_lock_index;
5064 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
5065 	}
5066 }
5067 
5068 static int raid5_congested(struct mddev *mddev, int bits)
5069 {
5070 	struct r5conf *conf = mddev->private;
5071 
5072 	/* No difference between reads and writes.  Just check
5073 	 * how busy the stripe_cache is
5074 	 */
5075 
5076 	if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
5077 		return 1;
5078 
5079 	/* Also checks whether there is pressure on r5cache log space */
5080 	if (test_bit(R5C_LOG_TIGHT, &conf->cache_state))
5081 		return 1;
5082 	if (conf->quiesce)
5083 		return 1;
5084 	if (atomic_read(&conf->empty_inactive_list_nr))
5085 		return 1;
5086 
5087 	return 0;
5088 }
5089 
5090 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
5091 {
5092 	struct r5conf *conf = mddev->private;
5093 	sector_t sector = bio->bi_iter.bi_sector;
5094 	unsigned int chunk_sectors;
5095 	unsigned int bio_sectors = bio_sectors(bio);
5096 
5097 	WARN_ON_ONCE(bio->bi_partno);
5098 
5099 	chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
5100 	return  chunk_sectors >=
5101 		((sector & (chunk_sectors - 1)) + bio_sectors);
5102 }
5103 
5104 /*
5105  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
5106  *  later sampled by raid5d.
5107  */
5108 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
5109 {
5110 	unsigned long flags;
5111 
5112 	spin_lock_irqsave(&conf->device_lock, flags);
5113 
5114 	bi->bi_next = conf->retry_read_aligned_list;
5115 	conf->retry_read_aligned_list = bi;
5116 
5117 	spin_unlock_irqrestore(&conf->device_lock, flags);
5118 	md_wakeup_thread(conf->mddev->thread);
5119 }
5120 
5121 static struct bio *remove_bio_from_retry(struct r5conf *conf,
5122 					 unsigned int *offset)
5123 {
5124 	struct bio *bi;
5125 
5126 	bi = conf->retry_read_aligned;
5127 	if (bi) {
5128 		*offset = conf->retry_read_offset;
5129 		conf->retry_read_aligned = NULL;
5130 		return bi;
5131 	}
5132 	bi = conf->retry_read_aligned_list;
5133 	if(bi) {
5134 		conf->retry_read_aligned_list = bi->bi_next;
5135 		bi->bi_next = NULL;
5136 		*offset = 0;
5137 	}
5138 
5139 	return bi;
5140 }
5141 
5142 /*
5143  *  The "raid5_align_endio" should check if the read succeeded and if it
5144  *  did, call bio_endio on the original bio (having bio_put the new bio
5145  *  first).
5146  *  If the read failed..
5147  */
5148 static void raid5_align_endio(struct bio *bi)
5149 {
5150 	struct bio* raid_bi  = bi->bi_private;
5151 	struct mddev *mddev;
5152 	struct r5conf *conf;
5153 	struct md_rdev *rdev;
5154 	blk_status_t error = bi->bi_status;
5155 
5156 	bio_put(bi);
5157 
5158 	rdev = (void*)raid_bi->bi_next;
5159 	raid_bi->bi_next = NULL;
5160 	mddev = rdev->mddev;
5161 	conf = mddev->private;
5162 
5163 	rdev_dec_pending(rdev, conf->mddev);
5164 
5165 	if (!error) {
5166 		bio_endio(raid_bi);
5167 		if (atomic_dec_and_test(&conf->active_aligned_reads))
5168 			wake_up(&conf->wait_for_quiescent);
5169 		return;
5170 	}
5171 
5172 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
5173 
5174 	add_bio_to_retry(raid_bi, conf);
5175 }
5176 
5177 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
5178 {
5179 	struct r5conf *conf = mddev->private;
5180 	int dd_idx;
5181 	struct bio* align_bi;
5182 	struct md_rdev *rdev;
5183 	sector_t end_sector;
5184 
5185 	if (!in_chunk_boundary(mddev, raid_bio)) {
5186 		pr_debug("%s: non aligned\n", __func__);
5187 		return 0;
5188 	}
5189 	/*
5190 	 * use bio_clone_fast to make a copy of the bio
5191 	 */
5192 	align_bi = bio_clone_fast(raid_bio, GFP_NOIO, mddev->bio_set);
5193 	if (!align_bi)
5194 		return 0;
5195 	/*
5196 	 *   set bi_end_io to a new function, and set bi_private to the
5197 	 *     original bio.
5198 	 */
5199 	align_bi->bi_end_io  = raid5_align_endio;
5200 	align_bi->bi_private = raid_bio;
5201 	/*
5202 	 *	compute position
5203 	 */
5204 	align_bi->bi_iter.bi_sector =
5205 		raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
5206 				     0, &dd_idx, NULL);
5207 
5208 	end_sector = bio_end_sector(align_bi);
5209 	rcu_read_lock();
5210 	rdev = rcu_dereference(conf->disks[dd_idx].replacement);
5211 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
5212 	    rdev->recovery_offset < end_sector) {
5213 		rdev = rcu_dereference(conf->disks[dd_idx].rdev);
5214 		if (rdev &&
5215 		    (test_bit(Faulty, &rdev->flags) ||
5216 		    !(test_bit(In_sync, &rdev->flags) ||
5217 		      rdev->recovery_offset >= end_sector)))
5218 			rdev = NULL;
5219 	}
5220 
5221 	if (r5c_big_stripe_cached(conf, align_bi->bi_iter.bi_sector)) {
5222 		rcu_read_unlock();
5223 		bio_put(align_bi);
5224 		return 0;
5225 	}
5226 
5227 	if (rdev) {
5228 		sector_t first_bad;
5229 		int bad_sectors;
5230 
5231 		atomic_inc(&rdev->nr_pending);
5232 		rcu_read_unlock();
5233 		raid_bio->bi_next = (void*)rdev;
5234 		bio_set_dev(align_bi, rdev->bdev);
5235 		bio_clear_flag(align_bi, BIO_SEG_VALID);
5236 
5237 		if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
5238 				bio_sectors(align_bi),
5239 				&first_bad, &bad_sectors)) {
5240 			bio_put(align_bi);
5241 			rdev_dec_pending(rdev, mddev);
5242 			return 0;
5243 		}
5244 
5245 		/* No reshape active, so we can trust rdev->data_offset */
5246 		align_bi->bi_iter.bi_sector += rdev->data_offset;
5247 
5248 		spin_lock_irq(&conf->device_lock);
5249 		wait_event_lock_irq(conf->wait_for_quiescent,
5250 				    conf->quiesce == 0,
5251 				    conf->device_lock);
5252 		atomic_inc(&conf->active_aligned_reads);
5253 		spin_unlock_irq(&conf->device_lock);
5254 
5255 		if (mddev->gendisk)
5256 			trace_block_bio_remap(align_bi->bi_disk->queue,
5257 					      align_bi, disk_devt(mddev->gendisk),
5258 					      raid_bio->bi_iter.bi_sector);
5259 		generic_make_request(align_bi);
5260 		return 1;
5261 	} else {
5262 		rcu_read_unlock();
5263 		bio_put(align_bi);
5264 		return 0;
5265 	}
5266 }
5267 
5268 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
5269 {
5270 	struct bio *split;
5271 	sector_t sector = raid_bio->bi_iter.bi_sector;
5272 	unsigned chunk_sects = mddev->chunk_sectors;
5273 	unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
5274 
5275 	if (sectors < bio_sectors(raid_bio)) {
5276 		struct r5conf *conf = mddev->private;
5277 		split = bio_split(raid_bio, sectors, GFP_NOIO, conf->bio_split);
5278 		bio_chain(split, raid_bio);
5279 		generic_make_request(raid_bio);
5280 		raid_bio = split;
5281 	}
5282 
5283 	if (!raid5_read_one_chunk(mddev, raid_bio))
5284 		return raid_bio;
5285 
5286 	return NULL;
5287 }
5288 
5289 /* __get_priority_stripe - get the next stripe to process
5290  *
5291  * Full stripe writes are allowed to pass preread active stripes up until
5292  * the bypass_threshold is exceeded.  In general the bypass_count
5293  * increments when the handle_list is handled before the hold_list; however, it
5294  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
5295  * stripe with in flight i/o.  The bypass_count will be reset when the
5296  * head of the hold_list has changed, i.e. the head was promoted to the
5297  * handle_list.
5298  */
5299 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
5300 {
5301 	struct stripe_head *sh, *tmp;
5302 	struct list_head *handle_list = NULL;
5303 	struct r5worker_group *wg;
5304 	bool second_try = !r5c_is_writeback(conf->log) &&
5305 		!r5l_log_disk_error(conf);
5306 	bool try_loprio = test_bit(R5C_LOG_TIGHT, &conf->cache_state) ||
5307 		r5l_log_disk_error(conf);
5308 
5309 again:
5310 	wg = NULL;
5311 	sh = NULL;
5312 	if (conf->worker_cnt_per_group == 0) {
5313 		handle_list = try_loprio ? &conf->loprio_list :
5314 					&conf->handle_list;
5315 	} else if (group != ANY_GROUP) {
5316 		handle_list = try_loprio ? &conf->worker_groups[group].loprio_list :
5317 				&conf->worker_groups[group].handle_list;
5318 		wg = &conf->worker_groups[group];
5319 	} else {
5320 		int i;
5321 		for (i = 0; i < conf->group_cnt; i++) {
5322 			handle_list = try_loprio ? &conf->worker_groups[i].loprio_list :
5323 				&conf->worker_groups[i].handle_list;
5324 			wg = &conf->worker_groups[i];
5325 			if (!list_empty(handle_list))
5326 				break;
5327 		}
5328 	}
5329 
5330 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
5331 		  __func__,
5332 		  list_empty(handle_list) ? "empty" : "busy",
5333 		  list_empty(&conf->hold_list) ? "empty" : "busy",
5334 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
5335 
5336 	if (!list_empty(handle_list)) {
5337 		sh = list_entry(handle_list->next, typeof(*sh), lru);
5338 
5339 		if (list_empty(&conf->hold_list))
5340 			conf->bypass_count = 0;
5341 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
5342 			if (conf->hold_list.next == conf->last_hold)
5343 				conf->bypass_count++;
5344 			else {
5345 				conf->last_hold = conf->hold_list.next;
5346 				conf->bypass_count -= conf->bypass_threshold;
5347 				if (conf->bypass_count < 0)
5348 					conf->bypass_count = 0;
5349 			}
5350 		}
5351 	} else if (!list_empty(&conf->hold_list) &&
5352 		   ((conf->bypass_threshold &&
5353 		     conf->bypass_count > conf->bypass_threshold) ||
5354 		    atomic_read(&conf->pending_full_writes) == 0)) {
5355 
5356 		list_for_each_entry(tmp, &conf->hold_list,  lru) {
5357 			if (conf->worker_cnt_per_group == 0 ||
5358 			    group == ANY_GROUP ||
5359 			    !cpu_online(tmp->cpu) ||
5360 			    cpu_to_group(tmp->cpu) == group) {
5361 				sh = tmp;
5362 				break;
5363 			}
5364 		}
5365 
5366 		if (sh) {
5367 			conf->bypass_count -= conf->bypass_threshold;
5368 			if (conf->bypass_count < 0)
5369 				conf->bypass_count = 0;
5370 		}
5371 		wg = NULL;
5372 	}
5373 
5374 	if (!sh) {
5375 		if (second_try)
5376 			return NULL;
5377 		second_try = true;
5378 		try_loprio = !try_loprio;
5379 		goto again;
5380 	}
5381 
5382 	if (wg) {
5383 		wg->stripes_cnt--;
5384 		sh->group = NULL;
5385 	}
5386 	list_del_init(&sh->lru);
5387 	BUG_ON(atomic_inc_return(&sh->count) != 1);
5388 	return sh;
5389 }
5390 
5391 struct raid5_plug_cb {
5392 	struct blk_plug_cb	cb;
5393 	struct list_head	list;
5394 	struct list_head	temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5395 };
5396 
5397 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5398 {
5399 	struct raid5_plug_cb *cb = container_of(
5400 		blk_cb, struct raid5_plug_cb, cb);
5401 	struct stripe_head *sh;
5402 	struct mddev *mddev = cb->cb.data;
5403 	struct r5conf *conf = mddev->private;
5404 	int cnt = 0;
5405 	int hash;
5406 
5407 	if (cb->list.next && !list_empty(&cb->list)) {
5408 		spin_lock_irq(&conf->device_lock);
5409 		while (!list_empty(&cb->list)) {
5410 			sh = list_first_entry(&cb->list, struct stripe_head, lru);
5411 			list_del_init(&sh->lru);
5412 			/*
5413 			 * avoid race release_stripe_plug() sees
5414 			 * STRIPE_ON_UNPLUG_LIST clear but the stripe
5415 			 * is still in our list
5416 			 */
5417 			smp_mb__before_atomic();
5418 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5419 			/*
5420 			 * STRIPE_ON_RELEASE_LIST could be set here. In that
5421 			 * case, the count is always > 1 here
5422 			 */
5423 			hash = sh->hash_lock_index;
5424 			__release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5425 			cnt++;
5426 		}
5427 		spin_unlock_irq(&conf->device_lock);
5428 	}
5429 	release_inactive_stripe_list(conf, cb->temp_inactive_list,
5430 				     NR_STRIPE_HASH_LOCKS);
5431 	if (mddev->queue)
5432 		trace_block_unplug(mddev->queue, cnt, !from_schedule);
5433 	kfree(cb);
5434 }
5435 
5436 static void release_stripe_plug(struct mddev *mddev,
5437 				struct stripe_head *sh)
5438 {
5439 	struct blk_plug_cb *blk_cb = blk_check_plugged(
5440 		raid5_unplug, mddev,
5441 		sizeof(struct raid5_plug_cb));
5442 	struct raid5_plug_cb *cb;
5443 
5444 	if (!blk_cb) {
5445 		raid5_release_stripe(sh);
5446 		return;
5447 	}
5448 
5449 	cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5450 
5451 	if (cb->list.next == NULL) {
5452 		int i;
5453 		INIT_LIST_HEAD(&cb->list);
5454 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5455 			INIT_LIST_HEAD(cb->temp_inactive_list + i);
5456 	}
5457 
5458 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5459 		list_add_tail(&sh->lru, &cb->list);
5460 	else
5461 		raid5_release_stripe(sh);
5462 }
5463 
5464 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5465 {
5466 	struct r5conf *conf = mddev->private;
5467 	sector_t logical_sector, last_sector;
5468 	struct stripe_head *sh;
5469 	int stripe_sectors;
5470 
5471 	if (mddev->reshape_position != MaxSector)
5472 		/* Skip discard while reshape is happening */
5473 		return;
5474 
5475 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5476 	last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5477 
5478 	bi->bi_next = NULL;
5479 
5480 	stripe_sectors = conf->chunk_sectors *
5481 		(conf->raid_disks - conf->max_degraded);
5482 	logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5483 					       stripe_sectors);
5484 	sector_div(last_sector, stripe_sectors);
5485 
5486 	logical_sector *= conf->chunk_sectors;
5487 	last_sector *= conf->chunk_sectors;
5488 
5489 	for (; logical_sector < last_sector;
5490 	     logical_sector += STRIPE_SECTORS) {
5491 		DEFINE_WAIT(w);
5492 		int d;
5493 	again:
5494 		sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
5495 		prepare_to_wait(&conf->wait_for_overlap, &w,
5496 				TASK_UNINTERRUPTIBLE);
5497 		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5498 		if (test_bit(STRIPE_SYNCING, &sh->state)) {
5499 			raid5_release_stripe(sh);
5500 			schedule();
5501 			goto again;
5502 		}
5503 		clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5504 		spin_lock_irq(&sh->stripe_lock);
5505 		for (d = 0; d < conf->raid_disks; d++) {
5506 			if (d == sh->pd_idx || d == sh->qd_idx)
5507 				continue;
5508 			if (sh->dev[d].towrite || sh->dev[d].toread) {
5509 				set_bit(R5_Overlap, &sh->dev[d].flags);
5510 				spin_unlock_irq(&sh->stripe_lock);
5511 				raid5_release_stripe(sh);
5512 				schedule();
5513 				goto again;
5514 			}
5515 		}
5516 		set_bit(STRIPE_DISCARD, &sh->state);
5517 		finish_wait(&conf->wait_for_overlap, &w);
5518 		sh->overwrite_disks = 0;
5519 		for (d = 0; d < conf->raid_disks; d++) {
5520 			if (d == sh->pd_idx || d == sh->qd_idx)
5521 				continue;
5522 			sh->dev[d].towrite = bi;
5523 			set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5524 			bio_inc_remaining(bi);
5525 			md_write_inc(mddev, bi);
5526 			sh->overwrite_disks++;
5527 		}
5528 		spin_unlock_irq(&sh->stripe_lock);
5529 		if (conf->mddev->bitmap) {
5530 			for (d = 0;
5531 			     d < conf->raid_disks - conf->max_degraded;
5532 			     d++)
5533 				bitmap_startwrite(mddev->bitmap,
5534 						  sh->sector,
5535 						  STRIPE_SECTORS,
5536 						  0);
5537 			sh->bm_seq = conf->seq_flush + 1;
5538 			set_bit(STRIPE_BIT_DELAY, &sh->state);
5539 		}
5540 
5541 		set_bit(STRIPE_HANDLE, &sh->state);
5542 		clear_bit(STRIPE_DELAYED, &sh->state);
5543 		if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5544 			atomic_inc(&conf->preread_active_stripes);
5545 		release_stripe_plug(mddev, sh);
5546 	}
5547 
5548 	bio_endio(bi);
5549 }
5550 
5551 static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
5552 {
5553 	struct r5conf *conf = mddev->private;
5554 	int dd_idx;
5555 	sector_t new_sector;
5556 	sector_t logical_sector, last_sector;
5557 	struct stripe_head *sh;
5558 	const int rw = bio_data_dir(bi);
5559 	DEFINE_WAIT(w);
5560 	bool do_prepare;
5561 	bool do_flush = false;
5562 
5563 	if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
5564 		int ret = r5l_handle_flush_request(conf->log, bi);
5565 
5566 		if (ret == 0)
5567 			return true;
5568 		if (ret == -ENODEV) {
5569 			md_flush_request(mddev, bi);
5570 			return true;
5571 		}
5572 		/* ret == -EAGAIN, fallback */
5573 		/*
5574 		 * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
5575 		 * we need to flush journal device
5576 		 */
5577 		do_flush = bi->bi_opf & REQ_PREFLUSH;
5578 	}
5579 
5580 	if (!md_write_start(mddev, bi))
5581 		return false;
5582 	/*
5583 	 * If array is degraded, better not do chunk aligned read because
5584 	 * later we might have to read it again in order to reconstruct
5585 	 * data on failed drives.
5586 	 */
5587 	if (rw == READ && mddev->degraded == 0 &&
5588 	    mddev->reshape_position == MaxSector) {
5589 		bi = chunk_aligned_read(mddev, bi);
5590 		if (!bi)
5591 			return true;
5592 	}
5593 
5594 	if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) {
5595 		make_discard_request(mddev, bi);
5596 		md_write_end(mddev);
5597 		return true;
5598 	}
5599 
5600 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5601 	last_sector = bio_end_sector(bi);
5602 	bi->bi_next = NULL;
5603 
5604 	prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5605 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5606 		int previous;
5607 		int seq;
5608 
5609 		do_prepare = false;
5610 	retry:
5611 		seq = read_seqcount_begin(&conf->gen_lock);
5612 		previous = 0;
5613 		if (do_prepare)
5614 			prepare_to_wait(&conf->wait_for_overlap, &w,
5615 				TASK_UNINTERRUPTIBLE);
5616 		if (unlikely(conf->reshape_progress != MaxSector)) {
5617 			/* spinlock is needed as reshape_progress may be
5618 			 * 64bit on a 32bit platform, and so it might be
5619 			 * possible to see a half-updated value
5620 			 * Of course reshape_progress could change after
5621 			 * the lock is dropped, so once we get a reference
5622 			 * to the stripe that we think it is, we will have
5623 			 * to check again.
5624 			 */
5625 			spin_lock_irq(&conf->device_lock);
5626 			if (mddev->reshape_backwards
5627 			    ? logical_sector < conf->reshape_progress
5628 			    : logical_sector >= conf->reshape_progress) {
5629 				previous = 1;
5630 			} else {
5631 				if (mddev->reshape_backwards
5632 				    ? logical_sector < conf->reshape_safe
5633 				    : logical_sector >= conf->reshape_safe) {
5634 					spin_unlock_irq(&conf->device_lock);
5635 					schedule();
5636 					do_prepare = true;
5637 					goto retry;
5638 				}
5639 			}
5640 			spin_unlock_irq(&conf->device_lock);
5641 		}
5642 
5643 		new_sector = raid5_compute_sector(conf, logical_sector,
5644 						  previous,
5645 						  &dd_idx, NULL);
5646 		pr_debug("raid456: raid5_make_request, sector %llu logical %llu\n",
5647 			(unsigned long long)new_sector,
5648 			(unsigned long long)logical_sector);
5649 
5650 		sh = raid5_get_active_stripe(conf, new_sector, previous,
5651 				       (bi->bi_opf & REQ_RAHEAD), 0);
5652 		if (sh) {
5653 			if (unlikely(previous)) {
5654 				/* expansion might have moved on while waiting for a
5655 				 * stripe, so we must do the range check again.
5656 				 * Expansion could still move past after this
5657 				 * test, but as we are holding a reference to
5658 				 * 'sh', we know that if that happens,
5659 				 *  STRIPE_EXPANDING will get set and the expansion
5660 				 * won't proceed until we finish with the stripe.
5661 				 */
5662 				int must_retry = 0;
5663 				spin_lock_irq(&conf->device_lock);
5664 				if (mddev->reshape_backwards
5665 				    ? logical_sector >= conf->reshape_progress
5666 				    : logical_sector < conf->reshape_progress)
5667 					/* mismatch, need to try again */
5668 					must_retry = 1;
5669 				spin_unlock_irq(&conf->device_lock);
5670 				if (must_retry) {
5671 					raid5_release_stripe(sh);
5672 					schedule();
5673 					do_prepare = true;
5674 					goto retry;
5675 				}
5676 			}
5677 			if (read_seqcount_retry(&conf->gen_lock, seq)) {
5678 				/* Might have got the wrong stripe_head
5679 				 * by accident
5680 				 */
5681 				raid5_release_stripe(sh);
5682 				goto retry;
5683 			}
5684 
5685 			if (rw == WRITE &&
5686 			    logical_sector >= mddev->suspend_lo &&
5687 			    logical_sector < mddev->suspend_hi) {
5688 				raid5_release_stripe(sh);
5689 				/* As the suspend_* range is controlled by
5690 				 * userspace, we want an interruptible
5691 				 * wait.
5692 				 */
5693 				prepare_to_wait(&conf->wait_for_overlap,
5694 						&w, TASK_INTERRUPTIBLE);
5695 				if (logical_sector >= mddev->suspend_lo &&
5696 				    logical_sector < mddev->suspend_hi) {
5697 					sigset_t full, old;
5698 					sigfillset(&full);
5699 					sigprocmask(SIG_BLOCK, &full, &old);
5700 					schedule();
5701 					sigprocmask(SIG_SETMASK, &old, NULL);
5702 					do_prepare = true;
5703 				}
5704 				goto retry;
5705 			}
5706 
5707 			if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5708 			    !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5709 				/* Stripe is busy expanding or
5710 				 * add failed due to overlap.  Flush everything
5711 				 * and wait a while
5712 				 */
5713 				md_wakeup_thread(mddev->thread);
5714 				raid5_release_stripe(sh);
5715 				schedule();
5716 				do_prepare = true;
5717 				goto retry;
5718 			}
5719 			if (do_flush) {
5720 				set_bit(STRIPE_R5C_PREFLUSH, &sh->state);
5721 				/* we only need flush for one stripe */
5722 				do_flush = false;
5723 			}
5724 
5725 			set_bit(STRIPE_HANDLE, &sh->state);
5726 			clear_bit(STRIPE_DELAYED, &sh->state);
5727 			if ((!sh->batch_head || sh == sh->batch_head) &&
5728 			    (bi->bi_opf & REQ_SYNC) &&
5729 			    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5730 				atomic_inc(&conf->preread_active_stripes);
5731 			release_stripe_plug(mddev, sh);
5732 		} else {
5733 			/* cannot get stripe for read-ahead, just give-up */
5734 			bi->bi_status = BLK_STS_IOERR;
5735 			break;
5736 		}
5737 	}
5738 	finish_wait(&conf->wait_for_overlap, &w);
5739 
5740 	if (rw == WRITE)
5741 		md_write_end(mddev);
5742 	bio_endio(bi);
5743 	return true;
5744 }
5745 
5746 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5747 
5748 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5749 {
5750 	/* reshaping is quite different to recovery/resync so it is
5751 	 * handled quite separately ... here.
5752 	 *
5753 	 * On each call to sync_request, we gather one chunk worth of
5754 	 * destination stripes and flag them as expanding.
5755 	 * Then we find all the source stripes and request reads.
5756 	 * As the reads complete, handle_stripe will copy the data
5757 	 * into the destination stripe and release that stripe.
5758 	 */
5759 	struct r5conf *conf = mddev->private;
5760 	struct stripe_head *sh;
5761 	sector_t first_sector, last_sector;
5762 	int raid_disks = conf->previous_raid_disks;
5763 	int data_disks = raid_disks - conf->max_degraded;
5764 	int new_data_disks = conf->raid_disks - conf->max_degraded;
5765 	int i;
5766 	int dd_idx;
5767 	sector_t writepos, readpos, safepos;
5768 	sector_t stripe_addr;
5769 	int reshape_sectors;
5770 	struct list_head stripes;
5771 	sector_t retn;
5772 
5773 	if (sector_nr == 0) {
5774 		/* If restarting in the middle, skip the initial sectors */
5775 		if (mddev->reshape_backwards &&
5776 		    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5777 			sector_nr = raid5_size(mddev, 0, 0)
5778 				- conf->reshape_progress;
5779 		} else if (mddev->reshape_backwards &&
5780 			   conf->reshape_progress == MaxSector) {
5781 			/* shouldn't happen, but just in case, finish up.*/
5782 			sector_nr = MaxSector;
5783 		} else if (!mddev->reshape_backwards &&
5784 			   conf->reshape_progress > 0)
5785 			sector_nr = conf->reshape_progress;
5786 		sector_div(sector_nr, new_data_disks);
5787 		if (sector_nr) {
5788 			mddev->curr_resync_completed = sector_nr;
5789 			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5790 			*skipped = 1;
5791 			retn = sector_nr;
5792 			goto finish;
5793 		}
5794 	}
5795 
5796 	/* We need to process a full chunk at a time.
5797 	 * If old and new chunk sizes differ, we need to process the
5798 	 * largest of these
5799 	 */
5800 
5801 	reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
5802 
5803 	/* We update the metadata at least every 10 seconds, or when
5804 	 * the data about to be copied would over-write the source of
5805 	 * the data at the front of the range.  i.e. one new_stripe
5806 	 * along from reshape_progress new_maps to after where
5807 	 * reshape_safe old_maps to
5808 	 */
5809 	writepos = conf->reshape_progress;
5810 	sector_div(writepos, new_data_disks);
5811 	readpos = conf->reshape_progress;
5812 	sector_div(readpos, data_disks);
5813 	safepos = conf->reshape_safe;
5814 	sector_div(safepos, data_disks);
5815 	if (mddev->reshape_backwards) {
5816 		BUG_ON(writepos < reshape_sectors);
5817 		writepos -= reshape_sectors;
5818 		readpos += reshape_sectors;
5819 		safepos += reshape_sectors;
5820 	} else {
5821 		writepos += reshape_sectors;
5822 		/* readpos and safepos are worst-case calculations.
5823 		 * A negative number is overly pessimistic, and causes
5824 		 * obvious problems for unsigned storage.  So clip to 0.
5825 		 */
5826 		readpos -= min_t(sector_t, reshape_sectors, readpos);
5827 		safepos -= min_t(sector_t, reshape_sectors, safepos);
5828 	}
5829 
5830 	/* Having calculated the 'writepos' possibly use it
5831 	 * to set 'stripe_addr' which is where we will write to.
5832 	 */
5833 	if (mddev->reshape_backwards) {
5834 		BUG_ON(conf->reshape_progress == 0);
5835 		stripe_addr = writepos;
5836 		BUG_ON((mddev->dev_sectors &
5837 			~((sector_t)reshape_sectors - 1))
5838 		       - reshape_sectors - stripe_addr
5839 		       != sector_nr);
5840 	} else {
5841 		BUG_ON(writepos != sector_nr + reshape_sectors);
5842 		stripe_addr = sector_nr;
5843 	}
5844 
5845 	/* 'writepos' is the most advanced device address we might write.
5846 	 * 'readpos' is the least advanced device address we might read.
5847 	 * 'safepos' is the least address recorded in the metadata as having
5848 	 *     been reshaped.
5849 	 * If there is a min_offset_diff, these are adjusted either by
5850 	 * increasing the safepos/readpos if diff is negative, or
5851 	 * increasing writepos if diff is positive.
5852 	 * If 'readpos' is then behind 'writepos', there is no way that we can
5853 	 * ensure safety in the face of a crash - that must be done by userspace
5854 	 * making a backup of the data.  So in that case there is no particular
5855 	 * rush to update metadata.
5856 	 * Otherwise if 'safepos' is behind 'writepos', then we really need to
5857 	 * update the metadata to advance 'safepos' to match 'readpos' so that
5858 	 * we can be safe in the event of a crash.
5859 	 * So we insist on updating metadata if safepos is behind writepos and
5860 	 * readpos is beyond writepos.
5861 	 * In any case, update the metadata every 10 seconds.
5862 	 * Maybe that number should be configurable, but I'm not sure it is
5863 	 * worth it.... maybe it could be a multiple of safemode_delay???
5864 	 */
5865 	if (conf->min_offset_diff < 0) {
5866 		safepos += -conf->min_offset_diff;
5867 		readpos += -conf->min_offset_diff;
5868 	} else
5869 		writepos += conf->min_offset_diff;
5870 
5871 	if ((mddev->reshape_backwards
5872 	     ? (safepos > writepos && readpos < writepos)
5873 	     : (safepos < writepos && readpos > writepos)) ||
5874 	    time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5875 		/* Cannot proceed until we've updated the superblock... */
5876 		wait_event(conf->wait_for_overlap,
5877 			   atomic_read(&conf->reshape_stripes)==0
5878 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5879 		if (atomic_read(&conf->reshape_stripes) != 0)
5880 			return 0;
5881 		mddev->reshape_position = conf->reshape_progress;
5882 		mddev->curr_resync_completed = sector_nr;
5883 		conf->reshape_checkpoint = jiffies;
5884 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5885 		md_wakeup_thread(mddev->thread);
5886 		wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
5887 			   test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5888 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5889 			return 0;
5890 		spin_lock_irq(&conf->device_lock);
5891 		conf->reshape_safe = mddev->reshape_position;
5892 		spin_unlock_irq(&conf->device_lock);
5893 		wake_up(&conf->wait_for_overlap);
5894 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5895 	}
5896 
5897 	INIT_LIST_HEAD(&stripes);
5898 	for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5899 		int j;
5900 		int skipped_disk = 0;
5901 		sh = raid5_get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5902 		set_bit(STRIPE_EXPANDING, &sh->state);
5903 		atomic_inc(&conf->reshape_stripes);
5904 		/* If any of this stripe is beyond the end of the old
5905 		 * array, then we need to zero those blocks
5906 		 */
5907 		for (j=sh->disks; j--;) {
5908 			sector_t s;
5909 			if (j == sh->pd_idx)
5910 				continue;
5911 			if (conf->level == 6 &&
5912 			    j == sh->qd_idx)
5913 				continue;
5914 			s = raid5_compute_blocknr(sh, j, 0);
5915 			if (s < raid5_size(mddev, 0, 0)) {
5916 				skipped_disk = 1;
5917 				continue;
5918 			}
5919 			memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5920 			set_bit(R5_Expanded, &sh->dev[j].flags);
5921 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
5922 		}
5923 		if (!skipped_disk) {
5924 			set_bit(STRIPE_EXPAND_READY, &sh->state);
5925 			set_bit(STRIPE_HANDLE, &sh->state);
5926 		}
5927 		list_add(&sh->lru, &stripes);
5928 	}
5929 	spin_lock_irq(&conf->device_lock);
5930 	if (mddev->reshape_backwards)
5931 		conf->reshape_progress -= reshape_sectors * new_data_disks;
5932 	else
5933 		conf->reshape_progress += reshape_sectors * new_data_disks;
5934 	spin_unlock_irq(&conf->device_lock);
5935 	/* Ok, those stripe are ready. We can start scheduling
5936 	 * reads on the source stripes.
5937 	 * The source stripes are determined by mapping the first and last
5938 	 * block on the destination stripes.
5939 	 */
5940 	first_sector =
5941 		raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5942 				     1, &dd_idx, NULL);
5943 	last_sector =
5944 		raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5945 					    * new_data_disks - 1),
5946 				     1, &dd_idx, NULL);
5947 	if (last_sector >= mddev->dev_sectors)
5948 		last_sector = mddev->dev_sectors - 1;
5949 	while (first_sector <= last_sector) {
5950 		sh = raid5_get_active_stripe(conf, first_sector, 1, 0, 1);
5951 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5952 		set_bit(STRIPE_HANDLE, &sh->state);
5953 		raid5_release_stripe(sh);
5954 		first_sector += STRIPE_SECTORS;
5955 	}
5956 	/* Now that the sources are clearly marked, we can release
5957 	 * the destination stripes
5958 	 */
5959 	while (!list_empty(&stripes)) {
5960 		sh = list_entry(stripes.next, struct stripe_head, lru);
5961 		list_del_init(&sh->lru);
5962 		raid5_release_stripe(sh);
5963 	}
5964 	/* If this takes us to the resync_max point where we have to pause,
5965 	 * then we need to write out the superblock.
5966 	 */
5967 	sector_nr += reshape_sectors;
5968 	retn = reshape_sectors;
5969 finish:
5970 	if (mddev->curr_resync_completed > mddev->resync_max ||
5971 	    (sector_nr - mddev->curr_resync_completed) * 2
5972 	    >= mddev->resync_max - mddev->curr_resync_completed) {
5973 		/* Cannot proceed until we've updated the superblock... */
5974 		wait_event(conf->wait_for_overlap,
5975 			   atomic_read(&conf->reshape_stripes) == 0
5976 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5977 		if (atomic_read(&conf->reshape_stripes) != 0)
5978 			goto ret;
5979 		mddev->reshape_position = conf->reshape_progress;
5980 		mddev->curr_resync_completed = sector_nr;
5981 		conf->reshape_checkpoint = jiffies;
5982 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5983 		md_wakeup_thread(mddev->thread);
5984 		wait_event(mddev->sb_wait,
5985 			   !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)
5986 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5987 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5988 			goto ret;
5989 		spin_lock_irq(&conf->device_lock);
5990 		conf->reshape_safe = mddev->reshape_position;
5991 		spin_unlock_irq(&conf->device_lock);
5992 		wake_up(&conf->wait_for_overlap);
5993 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5994 	}
5995 ret:
5996 	return retn;
5997 }
5998 
5999 static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_nr,
6000 					  int *skipped)
6001 {
6002 	struct r5conf *conf = mddev->private;
6003 	struct stripe_head *sh;
6004 	sector_t max_sector = mddev->dev_sectors;
6005 	sector_t sync_blocks;
6006 	int still_degraded = 0;
6007 	int i;
6008 
6009 	if (sector_nr >= max_sector) {
6010 		/* just being told to finish up .. nothing much to do */
6011 
6012 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
6013 			end_reshape(conf);
6014 			return 0;
6015 		}
6016 
6017 		if (mddev->curr_resync < max_sector) /* aborted */
6018 			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
6019 					&sync_blocks, 1);
6020 		else /* completed sync */
6021 			conf->fullsync = 0;
6022 		bitmap_close_sync(mddev->bitmap);
6023 
6024 		return 0;
6025 	}
6026 
6027 	/* Allow raid5_quiesce to complete */
6028 	wait_event(conf->wait_for_overlap, conf->quiesce != 2);
6029 
6030 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
6031 		return reshape_request(mddev, sector_nr, skipped);
6032 
6033 	/* No need to check resync_max as we never do more than one
6034 	 * stripe, and as resync_max will always be on a chunk boundary,
6035 	 * if the check in md_do_sync didn't fire, there is no chance
6036 	 * of overstepping resync_max here
6037 	 */
6038 
6039 	/* if there is too many failed drives and we are trying
6040 	 * to resync, then assert that we are finished, because there is
6041 	 * nothing we can do.
6042 	 */
6043 	if (mddev->degraded >= conf->max_degraded &&
6044 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
6045 		sector_t rv = mddev->dev_sectors - sector_nr;
6046 		*skipped = 1;
6047 		return rv;
6048 	}
6049 	if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
6050 	    !conf->fullsync &&
6051 	    !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
6052 	    sync_blocks >= STRIPE_SECTORS) {
6053 		/* we can skip this block, and probably more */
6054 		sync_blocks /= STRIPE_SECTORS;
6055 		*skipped = 1;
6056 		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
6057 	}
6058 
6059 	bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
6060 
6061 	sh = raid5_get_active_stripe(conf, sector_nr, 0, 1, 0);
6062 	if (sh == NULL) {
6063 		sh = raid5_get_active_stripe(conf, sector_nr, 0, 0, 0);
6064 		/* make sure we don't swamp the stripe cache if someone else
6065 		 * is trying to get access
6066 		 */
6067 		schedule_timeout_uninterruptible(1);
6068 	}
6069 	/* Need to check if array will still be degraded after recovery/resync
6070 	 * Note in case of > 1 drive failures it's possible we're rebuilding
6071 	 * one drive while leaving another faulty drive in array.
6072 	 */
6073 	rcu_read_lock();
6074 	for (i = 0; i < conf->raid_disks; i++) {
6075 		struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
6076 
6077 		if (rdev == NULL || test_bit(Faulty, &rdev->flags))
6078 			still_degraded = 1;
6079 	}
6080 	rcu_read_unlock();
6081 
6082 	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
6083 
6084 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
6085 	set_bit(STRIPE_HANDLE, &sh->state);
6086 
6087 	raid5_release_stripe(sh);
6088 
6089 	return STRIPE_SECTORS;
6090 }
6091 
6092 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio,
6093 			       unsigned int offset)
6094 {
6095 	/* We may not be able to submit a whole bio at once as there
6096 	 * may not be enough stripe_heads available.
6097 	 * We cannot pre-allocate enough stripe_heads as we may need
6098 	 * more than exist in the cache (if we allow ever large chunks).
6099 	 * So we do one stripe head at a time and record in
6100 	 * ->bi_hw_segments how many have been done.
6101 	 *
6102 	 * We *know* that this entire raid_bio is in one chunk, so
6103 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
6104 	 */
6105 	struct stripe_head *sh;
6106 	int dd_idx;
6107 	sector_t sector, logical_sector, last_sector;
6108 	int scnt = 0;
6109 	int handled = 0;
6110 
6111 	logical_sector = raid_bio->bi_iter.bi_sector &
6112 		~((sector_t)STRIPE_SECTORS-1);
6113 	sector = raid5_compute_sector(conf, logical_sector,
6114 				      0, &dd_idx, NULL);
6115 	last_sector = bio_end_sector(raid_bio);
6116 
6117 	for (; logical_sector < last_sector;
6118 	     logical_sector += STRIPE_SECTORS,
6119 		     sector += STRIPE_SECTORS,
6120 		     scnt++) {
6121 
6122 		if (scnt < offset)
6123 			/* already done this stripe */
6124 			continue;
6125 
6126 		sh = raid5_get_active_stripe(conf, sector, 0, 1, 1);
6127 
6128 		if (!sh) {
6129 			/* failed to get a stripe - must wait */
6130 			conf->retry_read_aligned = raid_bio;
6131 			conf->retry_read_offset = scnt;
6132 			return handled;
6133 		}
6134 
6135 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
6136 			raid5_release_stripe(sh);
6137 			conf->retry_read_aligned = raid_bio;
6138 			conf->retry_read_offset = scnt;
6139 			return handled;
6140 		}
6141 
6142 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
6143 		handle_stripe(sh);
6144 		raid5_release_stripe(sh);
6145 		handled++;
6146 	}
6147 
6148 	bio_endio(raid_bio);
6149 
6150 	if (atomic_dec_and_test(&conf->active_aligned_reads))
6151 		wake_up(&conf->wait_for_quiescent);
6152 	return handled;
6153 }
6154 
6155 static int handle_active_stripes(struct r5conf *conf, int group,
6156 				 struct r5worker *worker,
6157 				 struct list_head *temp_inactive_list)
6158 {
6159 	struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
6160 	int i, batch_size = 0, hash;
6161 	bool release_inactive = false;
6162 
6163 	while (batch_size < MAX_STRIPE_BATCH &&
6164 			(sh = __get_priority_stripe(conf, group)) != NULL)
6165 		batch[batch_size++] = sh;
6166 
6167 	if (batch_size == 0) {
6168 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6169 			if (!list_empty(temp_inactive_list + i))
6170 				break;
6171 		if (i == NR_STRIPE_HASH_LOCKS) {
6172 			spin_unlock_irq(&conf->device_lock);
6173 			r5l_flush_stripe_to_raid(conf->log);
6174 			spin_lock_irq(&conf->device_lock);
6175 			return batch_size;
6176 		}
6177 		release_inactive = true;
6178 	}
6179 	spin_unlock_irq(&conf->device_lock);
6180 
6181 	release_inactive_stripe_list(conf, temp_inactive_list,
6182 				     NR_STRIPE_HASH_LOCKS);
6183 
6184 	r5l_flush_stripe_to_raid(conf->log);
6185 	if (release_inactive) {
6186 		spin_lock_irq(&conf->device_lock);
6187 		return 0;
6188 	}
6189 
6190 	for (i = 0; i < batch_size; i++)
6191 		handle_stripe(batch[i]);
6192 	log_write_stripe_run(conf);
6193 
6194 	cond_resched();
6195 
6196 	spin_lock_irq(&conf->device_lock);
6197 	for (i = 0; i < batch_size; i++) {
6198 		hash = batch[i]->hash_lock_index;
6199 		__release_stripe(conf, batch[i], &temp_inactive_list[hash]);
6200 	}
6201 	return batch_size;
6202 }
6203 
6204 static void raid5_do_work(struct work_struct *work)
6205 {
6206 	struct r5worker *worker = container_of(work, struct r5worker, work);
6207 	struct r5worker_group *group = worker->group;
6208 	struct r5conf *conf = group->conf;
6209 	struct mddev *mddev = conf->mddev;
6210 	int group_id = group - conf->worker_groups;
6211 	int handled;
6212 	struct blk_plug plug;
6213 
6214 	pr_debug("+++ raid5worker active\n");
6215 
6216 	blk_start_plug(&plug);
6217 	handled = 0;
6218 	spin_lock_irq(&conf->device_lock);
6219 	while (1) {
6220 		int batch_size, released;
6221 
6222 		released = release_stripe_list(conf, worker->temp_inactive_list);
6223 
6224 		batch_size = handle_active_stripes(conf, group_id, worker,
6225 						   worker->temp_inactive_list);
6226 		worker->working = false;
6227 		if (!batch_size && !released)
6228 			break;
6229 		handled += batch_size;
6230 		wait_event_lock_irq(mddev->sb_wait,
6231 			!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags),
6232 			conf->device_lock);
6233 	}
6234 	pr_debug("%d stripes handled\n", handled);
6235 
6236 	spin_unlock_irq(&conf->device_lock);
6237 
6238 	flush_deferred_bios(conf);
6239 
6240 	r5l_flush_stripe_to_raid(conf->log);
6241 
6242 	async_tx_issue_pending_all();
6243 	blk_finish_plug(&plug);
6244 
6245 	pr_debug("--- raid5worker inactive\n");
6246 }
6247 
6248 /*
6249  * This is our raid5 kernel thread.
6250  *
6251  * We scan the hash table for stripes which can be handled now.
6252  * During the scan, completed stripes are saved for us by the interrupt
6253  * handler, so that they will not have to wait for our next wakeup.
6254  */
6255 static void raid5d(struct md_thread *thread)
6256 {
6257 	struct mddev *mddev = thread->mddev;
6258 	struct r5conf *conf = mddev->private;
6259 	int handled;
6260 	struct blk_plug plug;
6261 
6262 	pr_debug("+++ raid5d active\n");
6263 
6264 	md_check_recovery(mddev);
6265 
6266 	blk_start_plug(&plug);
6267 	handled = 0;
6268 	spin_lock_irq(&conf->device_lock);
6269 	while (1) {
6270 		struct bio *bio;
6271 		int batch_size, released;
6272 		unsigned int offset;
6273 
6274 		released = release_stripe_list(conf, conf->temp_inactive_list);
6275 		if (released)
6276 			clear_bit(R5_DID_ALLOC, &conf->cache_state);
6277 
6278 		if (
6279 		    !list_empty(&conf->bitmap_list)) {
6280 			/* Now is a good time to flush some bitmap updates */
6281 			conf->seq_flush++;
6282 			spin_unlock_irq(&conf->device_lock);
6283 			bitmap_unplug(mddev->bitmap);
6284 			spin_lock_irq(&conf->device_lock);
6285 			conf->seq_write = conf->seq_flush;
6286 			activate_bit_delay(conf, conf->temp_inactive_list);
6287 		}
6288 		raid5_activate_delayed(conf);
6289 
6290 		while ((bio = remove_bio_from_retry(conf, &offset))) {
6291 			int ok;
6292 			spin_unlock_irq(&conf->device_lock);
6293 			ok = retry_aligned_read(conf, bio, offset);
6294 			spin_lock_irq(&conf->device_lock);
6295 			if (!ok)
6296 				break;
6297 			handled++;
6298 		}
6299 
6300 		batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
6301 						   conf->temp_inactive_list);
6302 		if (!batch_size && !released)
6303 			break;
6304 		handled += batch_size;
6305 
6306 		if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
6307 			spin_unlock_irq(&conf->device_lock);
6308 			md_check_recovery(mddev);
6309 			spin_lock_irq(&conf->device_lock);
6310 		}
6311 	}
6312 	pr_debug("%d stripes handled\n", handled);
6313 
6314 	spin_unlock_irq(&conf->device_lock);
6315 	if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
6316 	    mutex_trylock(&conf->cache_size_mutex)) {
6317 		grow_one_stripe(conf, __GFP_NOWARN);
6318 		/* Set flag even if allocation failed.  This helps
6319 		 * slow down allocation requests when mem is short
6320 		 */
6321 		set_bit(R5_DID_ALLOC, &conf->cache_state);
6322 		mutex_unlock(&conf->cache_size_mutex);
6323 	}
6324 
6325 	flush_deferred_bios(conf);
6326 
6327 	r5l_flush_stripe_to_raid(conf->log);
6328 
6329 	async_tx_issue_pending_all();
6330 	blk_finish_plug(&plug);
6331 
6332 	pr_debug("--- raid5d inactive\n");
6333 }
6334 
6335 static ssize_t
6336 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
6337 {
6338 	struct r5conf *conf;
6339 	int ret = 0;
6340 	spin_lock(&mddev->lock);
6341 	conf = mddev->private;
6342 	if (conf)
6343 		ret = sprintf(page, "%d\n", conf->min_nr_stripes);
6344 	spin_unlock(&mddev->lock);
6345 	return ret;
6346 }
6347 
6348 int
6349 raid5_set_cache_size(struct mddev *mddev, int size)
6350 {
6351 	struct r5conf *conf = mddev->private;
6352 
6353 	if (size <= 16 || size > 32768)
6354 		return -EINVAL;
6355 
6356 	conf->min_nr_stripes = size;
6357 	mutex_lock(&conf->cache_size_mutex);
6358 	while (size < conf->max_nr_stripes &&
6359 	       drop_one_stripe(conf))
6360 		;
6361 	mutex_unlock(&conf->cache_size_mutex);
6362 
6363 	md_allow_write(mddev);
6364 
6365 	mutex_lock(&conf->cache_size_mutex);
6366 	while (size > conf->max_nr_stripes)
6367 		if (!grow_one_stripe(conf, GFP_KERNEL))
6368 			break;
6369 	mutex_unlock(&conf->cache_size_mutex);
6370 
6371 	return 0;
6372 }
6373 EXPORT_SYMBOL(raid5_set_cache_size);
6374 
6375 static ssize_t
6376 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6377 {
6378 	struct r5conf *conf;
6379 	unsigned long new;
6380 	int err;
6381 
6382 	if (len >= PAGE_SIZE)
6383 		return -EINVAL;
6384 	if (kstrtoul(page, 10, &new))
6385 		return -EINVAL;
6386 	err = mddev_lock(mddev);
6387 	if (err)
6388 		return err;
6389 	conf = mddev->private;
6390 	if (!conf)
6391 		err = -ENODEV;
6392 	else
6393 		err = raid5_set_cache_size(mddev, new);
6394 	mddev_unlock(mddev);
6395 
6396 	return err ?: len;
6397 }
6398 
6399 static struct md_sysfs_entry
6400 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6401 				raid5_show_stripe_cache_size,
6402 				raid5_store_stripe_cache_size);
6403 
6404 static ssize_t
6405 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6406 {
6407 	struct r5conf *conf = mddev->private;
6408 	if (conf)
6409 		return sprintf(page, "%d\n", conf->rmw_level);
6410 	else
6411 		return 0;
6412 }
6413 
6414 static ssize_t
6415 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6416 {
6417 	struct r5conf *conf = mddev->private;
6418 	unsigned long new;
6419 
6420 	if (!conf)
6421 		return -ENODEV;
6422 
6423 	if (len >= PAGE_SIZE)
6424 		return -EINVAL;
6425 
6426 	if (kstrtoul(page, 10, &new))
6427 		return -EINVAL;
6428 
6429 	if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6430 		return -EINVAL;
6431 
6432 	if (new != PARITY_DISABLE_RMW &&
6433 	    new != PARITY_ENABLE_RMW &&
6434 	    new != PARITY_PREFER_RMW)
6435 		return -EINVAL;
6436 
6437 	conf->rmw_level = new;
6438 	return len;
6439 }
6440 
6441 static struct md_sysfs_entry
6442 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
6443 			 raid5_show_rmw_level,
6444 			 raid5_store_rmw_level);
6445 
6446 
6447 static ssize_t
6448 raid5_show_preread_threshold(struct mddev *mddev, char *page)
6449 {
6450 	struct r5conf *conf;
6451 	int ret = 0;
6452 	spin_lock(&mddev->lock);
6453 	conf = mddev->private;
6454 	if (conf)
6455 		ret = sprintf(page, "%d\n", conf->bypass_threshold);
6456 	spin_unlock(&mddev->lock);
6457 	return ret;
6458 }
6459 
6460 static ssize_t
6461 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
6462 {
6463 	struct r5conf *conf;
6464 	unsigned long new;
6465 	int err;
6466 
6467 	if (len >= PAGE_SIZE)
6468 		return -EINVAL;
6469 	if (kstrtoul(page, 10, &new))
6470 		return -EINVAL;
6471 
6472 	err = mddev_lock(mddev);
6473 	if (err)
6474 		return err;
6475 	conf = mddev->private;
6476 	if (!conf)
6477 		err = -ENODEV;
6478 	else if (new > conf->min_nr_stripes)
6479 		err = -EINVAL;
6480 	else
6481 		conf->bypass_threshold = new;
6482 	mddev_unlock(mddev);
6483 	return err ?: len;
6484 }
6485 
6486 static struct md_sysfs_entry
6487 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6488 					S_IRUGO | S_IWUSR,
6489 					raid5_show_preread_threshold,
6490 					raid5_store_preread_threshold);
6491 
6492 static ssize_t
6493 raid5_show_skip_copy(struct mddev *mddev, char *page)
6494 {
6495 	struct r5conf *conf;
6496 	int ret = 0;
6497 	spin_lock(&mddev->lock);
6498 	conf = mddev->private;
6499 	if (conf)
6500 		ret = sprintf(page, "%d\n", conf->skip_copy);
6501 	spin_unlock(&mddev->lock);
6502 	return ret;
6503 }
6504 
6505 static ssize_t
6506 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6507 {
6508 	struct r5conf *conf;
6509 	unsigned long new;
6510 	int err;
6511 
6512 	if (len >= PAGE_SIZE)
6513 		return -EINVAL;
6514 	if (kstrtoul(page, 10, &new))
6515 		return -EINVAL;
6516 	new = !!new;
6517 
6518 	err = mddev_lock(mddev);
6519 	if (err)
6520 		return err;
6521 	conf = mddev->private;
6522 	if (!conf)
6523 		err = -ENODEV;
6524 	else if (new != conf->skip_copy) {
6525 		mddev_suspend(mddev);
6526 		conf->skip_copy = new;
6527 		if (new)
6528 			mddev->queue->backing_dev_info->capabilities |=
6529 				BDI_CAP_STABLE_WRITES;
6530 		else
6531 			mddev->queue->backing_dev_info->capabilities &=
6532 				~BDI_CAP_STABLE_WRITES;
6533 		mddev_resume(mddev);
6534 	}
6535 	mddev_unlock(mddev);
6536 	return err ?: len;
6537 }
6538 
6539 static struct md_sysfs_entry
6540 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6541 					raid5_show_skip_copy,
6542 					raid5_store_skip_copy);
6543 
6544 static ssize_t
6545 stripe_cache_active_show(struct mddev *mddev, char *page)
6546 {
6547 	struct r5conf *conf = mddev->private;
6548 	if (conf)
6549 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6550 	else
6551 		return 0;
6552 }
6553 
6554 static struct md_sysfs_entry
6555 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6556 
6557 static ssize_t
6558 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6559 {
6560 	struct r5conf *conf;
6561 	int ret = 0;
6562 	spin_lock(&mddev->lock);
6563 	conf = mddev->private;
6564 	if (conf)
6565 		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6566 	spin_unlock(&mddev->lock);
6567 	return ret;
6568 }
6569 
6570 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6571 			       int *group_cnt,
6572 			       int *worker_cnt_per_group,
6573 			       struct r5worker_group **worker_groups);
6574 static ssize_t
6575 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6576 {
6577 	struct r5conf *conf;
6578 	unsigned int new;
6579 	int err;
6580 	struct r5worker_group *new_groups, *old_groups;
6581 	int group_cnt, worker_cnt_per_group;
6582 
6583 	if (len >= PAGE_SIZE)
6584 		return -EINVAL;
6585 	if (kstrtouint(page, 10, &new))
6586 		return -EINVAL;
6587 	/* 8192 should be big enough */
6588 	if (new > 8192)
6589 		return -EINVAL;
6590 
6591 	err = mddev_lock(mddev);
6592 	if (err)
6593 		return err;
6594 	conf = mddev->private;
6595 	if (!conf)
6596 		err = -ENODEV;
6597 	else if (new != conf->worker_cnt_per_group) {
6598 		mddev_suspend(mddev);
6599 
6600 		old_groups = conf->worker_groups;
6601 		if (old_groups)
6602 			flush_workqueue(raid5_wq);
6603 
6604 		err = alloc_thread_groups(conf, new,
6605 					  &group_cnt, &worker_cnt_per_group,
6606 					  &new_groups);
6607 		if (!err) {
6608 			spin_lock_irq(&conf->device_lock);
6609 			conf->group_cnt = group_cnt;
6610 			conf->worker_cnt_per_group = worker_cnt_per_group;
6611 			conf->worker_groups = new_groups;
6612 			spin_unlock_irq(&conf->device_lock);
6613 
6614 			if (old_groups)
6615 				kfree(old_groups[0].workers);
6616 			kfree(old_groups);
6617 		}
6618 		mddev_resume(mddev);
6619 	}
6620 	mddev_unlock(mddev);
6621 
6622 	return err ?: len;
6623 }
6624 
6625 static struct md_sysfs_entry
6626 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6627 				raid5_show_group_thread_cnt,
6628 				raid5_store_group_thread_cnt);
6629 
6630 static struct attribute *raid5_attrs[] =  {
6631 	&raid5_stripecache_size.attr,
6632 	&raid5_stripecache_active.attr,
6633 	&raid5_preread_bypass_threshold.attr,
6634 	&raid5_group_thread_cnt.attr,
6635 	&raid5_skip_copy.attr,
6636 	&raid5_rmw_level.attr,
6637 	&r5c_journal_mode.attr,
6638 	NULL,
6639 };
6640 static struct attribute_group raid5_attrs_group = {
6641 	.name = NULL,
6642 	.attrs = raid5_attrs,
6643 };
6644 
6645 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6646 			       int *group_cnt,
6647 			       int *worker_cnt_per_group,
6648 			       struct r5worker_group **worker_groups)
6649 {
6650 	int i, j, k;
6651 	ssize_t size;
6652 	struct r5worker *workers;
6653 
6654 	*worker_cnt_per_group = cnt;
6655 	if (cnt == 0) {
6656 		*group_cnt = 0;
6657 		*worker_groups = NULL;
6658 		return 0;
6659 	}
6660 	*group_cnt = num_possible_nodes();
6661 	size = sizeof(struct r5worker) * cnt;
6662 	workers = kzalloc(size * *group_cnt, GFP_NOIO);
6663 	*worker_groups = kzalloc(sizeof(struct r5worker_group) *
6664 				*group_cnt, GFP_NOIO);
6665 	if (!*worker_groups || !workers) {
6666 		kfree(workers);
6667 		kfree(*worker_groups);
6668 		return -ENOMEM;
6669 	}
6670 
6671 	for (i = 0; i < *group_cnt; i++) {
6672 		struct r5worker_group *group;
6673 
6674 		group = &(*worker_groups)[i];
6675 		INIT_LIST_HEAD(&group->handle_list);
6676 		INIT_LIST_HEAD(&group->loprio_list);
6677 		group->conf = conf;
6678 		group->workers = workers + i * cnt;
6679 
6680 		for (j = 0; j < cnt; j++) {
6681 			struct r5worker *worker = group->workers + j;
6682 			worker->group = group;
6683 			INIT_WORK(&worker->work, raid5_do_work);
6684 
6685 			for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6686 				INIT_LIST_HEAD(worker->temp_inactive_list + k);
6687 		}
6688 	}
6689 
6690 	return 0;
6691 }
6692 
6693 static void free_thread_groups(struct r5conf *conf)
6694 {
6695 	if (conf->worker_groups)
6696 		kfree(conf->worker_groups[0].workers);
6697 	kfree(conf->worker_groups);
6698 	conf->worker_groups = NULL;
6699 }
6700 
6701 static sector_t
6702 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6703 {
6704 	struct r5conf *conf = mddev->private;
6705 
6706 	if (!sectors)
6707 		sectors = mddev->dev_sectors;
6708 	if (!raid_disks)
6709 		/* size is defined by the smallest of previous and new size */
6710 		raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6711 
6712 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
6713 	sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
6714 	return sectors * (raid_disks - conf->max_degraded);
6715 }
6716 
6717 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6718 {
6719 	safe_put_page(percpu->spare_page);
6720 	if (percpu->scribble)
6721 		flex_array_free(percpu->scribble);
6722 	percpu->spare_page = NULL;
6723 	percpu->scribble = NULL;
6724 }
6725 
6726 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6727 {
6728 	if (conf->level == 6 && !percpu->spare_page)
6729 		percpu->spare_page = alloc_page(GFP_KERNEL);
6730 	if (!percpu->scribble)
6731 		percpu->scribble = scribble_alloc(max(conf->raid_disks,
6732 						      conf->previous_raid_disks),
6733 						  max(conf->chunk_sectors,
6734 						      conf->prev_chunk_sectors)
6735 						   / STRIPE_SECTORS,
6736 						  GFP_KERNEL);
6737 
6738 	if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6739 		free_scratch_buffer(conf, percpu);
6740 		return -ENOMEM;
6741 	}
6742 
6743 	return 0;
6744 }
6745 
6746 static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
6747 {
6748 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6749 
6750 	free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6751 	return 0;
6752 }
6753 
6754 static void raid5_free_percpu(struct r5conf *conf)
6755 {
6756 	if (!conf->percpu)
6757 		return;
6758 
6759 	cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6760 	free_percpu(conf->percpu);
6761 }
6762 
6763 static void free_conf(struct r5conf *conf)
6764 {
6765 	int i;
6766 
6767 	log_exit(conf);
6768 
6769 	if (conf->shrinker.nr_deferred)
6770 		unregister_shrinker(&conf->shrinker);
6771 
6772 	free_thread_groups(conf);
6773 	shrink_stripes(conf);
6774 	raid5_free_percpu(conf);
6775 	for (i = 0; i < conf->pool_size; i++)
6776 		if (conf->disks[i].extra_page)
6777 			put_page(conf->disks[i].extra_page);
6778 	kfree(conf->disks);
6779 	if (conf->bio_split)
6780 		bioset_free(conf->bio_split);
6781 	kfree(conf->stripe_hashtbl);
6782 	kfree(conf->pending_data);
6783 	kfree(conf);
6784 }
6785 
6786 static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
6787 {
6788 	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6789 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6790 
6791 	if (alloc_scratch_buffer(conf, percpu)) {
6792 		pr_warn("%s: failed memory allocation for cpu%u\n",
6793 			__func__, cpu);
6794 		return -ENOMEM;
6795 	}
6796 	return 0;
6797 }
6798 
6799 static int raid5_alloc_percpu(struct r5conf *conf)
6800 {
6801 	int err = 0;
6802 
6803 	conf->percpu = alloc_percpu(struct raid5_percpu);
6804 	if (!conf->percpu)
6805 		return -ENOMEM;
6806 
6807 	err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6808 	if (!err) {
6809 		conf->scribble_disks = max(conf->raid_disks,
6810 			conf->previous_raid_disks);
6811 		conf->scribble_sectors = max(conf->chunk_sectors,
6812 			conf->prev_chunk_sectors);
6813 	}
6814 	return err;
6815 }
6816 
6817 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6818 				      struct shrink_control *sc)
6819 {
6820 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6821 	unsigned long ret = SHRINK_STOP;
6822 
6823 	if (mutex_trylock(&conf->cache_size_mutex)) {
6824 		ret= 0;
6825 		while (ret < sc->nr_to_scan &&
6826 		       conf->max_nr_stripes > conf->min_nr_stripes) {
6827 			if (drop_one_stripe(conf) == 0) {
6828 				ret = SHRINK_STOP;
6829 				break;
6830 			}
6831 			ret++;
6832 		}
6833 		mutex_unlock(&conf->cache_size_mutex);
6834 	}
6835 	return ret;
6836 }
6837 
6838 static unsigned long raid5_cache_count(struct shrinker *shrink,
6839 				       struct shrink_control *sc)
6840 {
6841 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6842 
6843 	if (conf->max_nr_stripes < conf->min_nr_stripes)
6844 		/* unlikely, but not impossible */
6845 		return 0;
6846 	return conf->max_nr_stripes - conf->min_nr_stripes;
6847 }
6848 
6849 static struct r5conf *setup_conf(struct mddev *mddev)
6850 {
6851 	struct r5conf *conf;
6852 	int raid_disk, memory, max_disks;
6853 	struct md_rdev *rdev;
6854 	struct disk_info *disk;
6855 	char pers_name[6];
6856 	int i;
6857 	int group_cnt, worker_cnt_per_group;
6858 	struct r5worker_group *new_group;
6859 
6860 	if (mddev->new_level != 5
6861 	    && mddev->new_level != 4
6862 	    && mddev->new_level != 6) {
6863 		pr_warn("md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6864 			mdname(mddev), mddev->new_level);
6865 		return ERR_PTR(-EIO);
6866 	}
6867 	if ((mddev->new_level == 5
6868 	     && !algorithm_valid_raid5(mddev->new_layout)) ||
6869 	    (mddev->new_level == 6
6870 	     && !algorithm_valid_raid6(mddev->new_layout))) {
6871 		pr_warn("md/raid:%s: layout %d not supported\n",
6872 			mdname(mddev), mddev->new_layout);
6873 		return ERR_PTR(-EIO);
6874 	}
6875 	if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6876 		pr_warn("md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6877 			mdname(mddev), mddev->raid_disks);
6878 		return ERR_PTR(-EINVAL);
6879 	}
6880 
6881 	if (!mddev->new_chunk_sectors ||
6882 	    (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6883 	    !is_power_of_2(mddev->new_chunk_sectors)) {
6884 		pr_warn("md/raid:%s: invalid chunk size %d\n",
6885 			mdname(mddev), mddev->new_chunk_sectors << 9);
6886 		return ERR_PTR(-EINVAL);
6887 	}
6888 
6889 	conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6890 	if (conf == NULL)
6891 		goto abort;
6892 	INIT_LIST_HEAD(&conf->free_list);
6893 	INIT_LIST_HEAD(&conf->pending_list);
6894 	conf->pending_data = kzalloc(sizeof(struct r5pending_data) *
6895 		PENDING_IO_MAX, GFP_KERNEL);
6896 	if (!conf->pending_data)
6897 		goto abort;
6898 	for (i = 0; i < PENDING_IO_MAX; i++)
6899 		list_add(&conf->pending_data[i].sibling, &conf->free_list);
6900 	/* Don't enable multi-threading by default*/
6901 	if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6902 				 &new_group)) {
6903 		conf->group_cnt = group_cnt;
6904 		conf->worker_cnt_per_group = worker_cnt_per_group;
6905 		conf->worker_groups = new_group;
6906 	} else
6907 		goto abort;
6908 	spin_lock_init(&conf->device_lock);
6909 	seqcount_init(&conf->gen_lock);
6910 	mutex_init(&conf->cache_size_mutex);
6911 	init_waitqueue_head(&conf->wait_for_quiescent);
6912 	init_waitqueue_head(&conf->wait_for_stripe);
6913 	init_waitqueue_head(&conf->wait_for_overlap);
6914 	INIT_LIST_HEAD(&conf->handle_list);
6915 	INIT_LIST_HEAD(&conf->loprio_list);
6916 	INIT_LIST_HEAD(&conf->hold_list);
6917 	INIT_LIST_HEAD(&conf->delayed_list);
6918 	INIT_LIST_HEAD(&conf->bitmap_list);
6919 	init_llist_head(&conf->released_stripes);
6920 	atomic_set(&conf->active_stripes, 0);
6921 	atomic_set(&conf->preread_active_stripes, 0);
6922 	atomic_set(&conf->active_aligned_reads, 0);
6923 	spin_lock_init(&conf->pending_bios_lock);
6924 	conf->batch_bio_dispatch = true;
6925 	rdev_for_each(rdev, mddev) {
6926 		if (test_bit(Journal, &rdev->flags))
6927 			continue;
6928 		if (blk_queue_nonrot(bdev_get_queue(rdev->bdev))) {
6929 			conf->batch_bio_dispatch = false;
6930 			break;
6931 		}
6932 	}
6933 
6934 	conf->bypass_threshold = BYPASS_THRESHOLD;
6935 	conf->recovery_disabled = mddev->recovery_disabled - 1;
6936 
6937 	conf->raid_disks = mddev->raid_disks;
6938 	if (mddev->reshape_position == MaxSector)
6939 		conf->previous_raid_disks = mddev->raid_disks;
6940 	else
6941 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6942 	max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6943 
6944 	conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6945 			      GFP_KERNEL);
6946 
6947 	if (!conf->disks)
6948 		goto abort;
6949 
6950 	for (i = 0; i < max_disks; i++) {
6951 		conf->disks[i].extra_page = alloc_page(GFP_KERNEL);
6952 		if (!conf->disks[i].extra_page)
6953 			goto abort;
6954 	}
6955 
6956 	conf->bio_split = bioset_create(BIO_POOL_SIZE, 0, 0);
6957 	if (!conf->bio_split)
6958 		goto abort;
6959 	conf->mddev = mddev;
6960 
6961 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6962 		goto abort;
6963 
6964 	/* We init hash_locks[0] separately to that it can be used
6965 	 * as the reference lock in the spin_lock_nest_lock() call
6966 	 * in lock_all_device_hash_locks_irq in order to convince
6967 	 * lockdep that we know what we are doing.
6968 	 */
6969 	spin_lock_init(conf->hash_locks);
6970 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6971 		spin_lock_init(conf->hash_locks + i);
6972 
6973 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6974 		INIT_LIST_HEAD(conf->inactive_list + i);
6975 
6976 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6977 		INIT_LIST_HEAD(conf->temp_inactive_list + i);
6978 
6979 	atomic_set(&conf->r5c_cached_full_stripes, 0);
6980 	INIT_LIST_HEAD(&conf->r5c_full_stripe_list);
6981 	atomic_set(&conf->r5c_cached_partial_stripes, 0);
6982 	INIT_LIST_HEAD(&conf->r5c_partial_stripe_list);
6983 	atomic_set(&conf->r5c_flushing_full_stripes, 0);
6984 	atomic_set(&conf->r5c_flushing_partial_stripes, 0);
6985 
6986 	conf->level = mddev->new_level;
6987 	conf->chunk_sectors = mddev->new_chunk_sectors;
6988 	if (raid5_alloc_percpu(conf) != 0)
6989 		goto abort;
6990 
6991 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6992 
6993 	rdev_for_each(rdev, mddev) {
6994 		raid_disk = rdev->raid_disk;
6995 		if (raid_disk >= max_disks
6996 		    || raid_disk < 0 || test_bit(Journal, &rdev->flags))
6997 			continue;
6998 		disk = conf->disks + raid_disk;
6999 
7000 		if (test_bit(Replacement, &rdev->flags)) {
7001 			if (disk->replacement)
7002 				goto abort;
7003 			disk->replacement = rdev;
7004 		} else {
7005 			if (disk->rdev)
7006 				goto abort;
7007 			disk->rdev = rdev;
7008 		}
7009 
7010 		if (test_bit(In_sync, &rdev->flags)) {
7011 			char b[BDEVNAME_SIZE];
7012 			pr_info("md/raid:%s: device %s operational as raid disk %d\n",
7013 				mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
7014 		} else if (rdev->saved_raid_disk != raid_disk)
7015 			/* Cannot rely on bitmap to complete recovery */
7016 			conf->fullsync = 1;
7017 	}
7018 
7019 	conf->level = mddev->new_level;
7020 	if (conf->level == 6) {
7021 		conf->max_degraded = 2;
7022 		if (raid6_call.xor_syndrome)
7023 			conf->rmw_level = PARITY_ENABLE_RMW;
7024 		else
7025 			conf->rmw_level = PARITY_DISABLE_RMW;
7026 	} else {
7027 		conf->max_degraded = 1;
7028 		conf->rmw_level = PARITY_ENABLE_RMW;
7029 	}
7030 	conf->algorithm = mddev->new_layout;
7031 	conf->reshape_progress = mddev->reshape_position;
7032 	if (conf->reshape_progress != MaxSector) {
7033 		conf->prev_chunk_sectors = mddev->chunk_sectors;
7034 		conf->prev_algo = mddev->layout;
7035 	} else {
7036 		conf->prev_chunk_sectors = conf->chunk_sectors;
7037 		conf->prev_algo = conf->algorithm;
7038 	}
7039 
7040 	conf->min_nr_stripes = NR_STRIPES;
7041 	if (mddev->reshape_position != MaxSector) {
7042 		int stripes = max_t(int,
7043 			((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4,
7044 			((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4);
7045 		conf->min_nr_stripes = max(NR_STRIPES, stripes);
7046 		if (conf->min_nr_stripes != NR_STRIPES)
7047 			pr_info("md/raid:%s: force stripe size %d for reshape\n",
7048 				mdname(mddev), conf->min_nr_stripes);
7049 	}
7050 	memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
7051 		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
7052 	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
7053 	if (grow_stripes(conf, conf->min_nr_stripes)) {
7054 		pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
7055 			mdname(mddev), memory);
7056 		goto abort;
7057 	} else
7058 		pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
7059 	/*
7060 	 * Losing a stripe head costs more than the time to refill it,
7061 	 * it reduces the queue depth and so can hurt throughput.
7062 	 * So set it rather large, scaled by number of devices.
7063 	 */
7064 	conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
7065 	conf->shrinker.scan_objects = raid5_cache_scan;
7066 	conf->shrinker.count_objects = raid5_cache_count;
7067 	conf->shrinker.batch = 128;
7068 	conf->shrinker.flags = 0;
7069 	if (register_shrinker(&conf->shrinker)) {
7070 		pr_warn("md/raid:%s: couldn't register shrinker.\n",
7071 			mdname(mddev));
7072 		goto abort;
7073 	}
7074 
7075 	sprintf(pers_name, "raid%d", mddev->new_level);
7076 	conf->thread = md_register_thread(raid5d, mddev, pers_name);
7077 	if (!conf->thread) {
7078 		pr_warn("md/raid:%s: couldn't allocate thread.\n",
7079 			mdname(mddev));
7080 		goto abort;
7081 	}
7082 
7083 	return conf;
7084 
7085  abort:
7086 	if (conf) {
7087 		free_conf(conf);
7088 		return ERR_PTR(-EIO);
7089 	} else
7090 		return ERR_PTR(-ENOMEM);
7091 }
7092 
7093 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
7094 {
7095 	switch (algo) {
7096 	case ALGORITHM_PARITY_0:
7097 		if (raid_disk < max_degraded)
7098 			return 1;
7099 		break;
7100 	case ALGORITHM_PARITY_N:
7101 		if (raid_disk >= raid_disks - max_degraded)
7102 			return 1;
7103 		break;
7104 	case ALGORITHM_PARITY_0_6:
7105 		if (raid_disk == 0 ||
7106 		    raid_disk == raid_disks - 1)
7107 			return 1;
7108 		break;
7109 	case ALGORITHM_LEFT_ASYMMETRIC_6:
7110 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
7111 	case ALGORITHM_LEFT_SYMMETRIC_6:
7112 	case ALGORITHM_RIGHT_SYMMETRIC_6:
7113 		if (raid_disk == raid_disks - 1)
7114 			return 1;
7115 	}
7116 	return 0;
7117 }
7118 
7119 static int raid5_run(struct mddev *mddev)
7120 {
7121 	struct r5conf *conf;
7122 	int working_disks = 0;
7123 	int dirty_parity_disks = 0;
7124 	struct md_rdev *rdev;
7125 	struct md_rdev *journal_dev = NULL;
7126 	sector_t reshape_offset = 0;
7127 	int i;
7128 	long long min_offset_diff = 0;
7129 	int first = 1;
7130 
7131 	if (mddev_init_writes_pending(mddev) < 0)
7132 		return -ENOMEM;
7133 
7134 	if (mddev->recovery_cp != MaxSector)
7135 		pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
7136 			  mdname(mddev));
7137 
7138 	rdev_for_each(rdev, mddev) {
7139 		long long diff;
7140 
7141 		if (test_bit(Journal, &rdev->flags)) {
7142 			journal_dev = rdev;
7143 			continue;
7144 		}
7145 		if (rdev->raid_disk < 0)
7146 			continue;
7147 		diff = (rdev->new_data_offset - rdev->data_offset);
7148 		if (first) {
7149 			min_offset_diff = diff;
7150 			first = 0;
7151 		} else if (mddev->reshape_backwards &&
7152 			 diff < min_offset_diff)
7153 			min_offset_diff = diff;
7154 		else if (!mddev->reshape_backwards &&
7155 			 diff > min_offset_diff)
7156 			min_offset_diff = diff;
7157 	}
7158 
7159 	if (mddev->reshape_position != MaxSector) {
7160 		/* Check that we can continue the reshape.
7161 		 * Difficulties arise if the stripe we would write to
7162 		 * next is at or after the stripe we would read from next.
7163 		 * For a reshape that changes the number of devices, this
7164 		 * is only possible for a very short time, and mdadm makes
7165 		 * sure that time appears to have past before assembling
7166 		 * the array.  So we fail if that time hasn't passed.
7167 		 * For a reshape that keeps the number of devices the same
7168 		 * mdadm must be monitoring the reshape can keeping the
7169 		 * critical areas read-only and backed up.  It will start
7170 		 * the array in read-only mode, so we check for that.
7171 		 */
7172 		sector_t here_new, here_old;
7173 		int old_disks;
7174 		int max_degraded = (mddev->level == 6 ? 2 : 1);
7175 		int chunk_sectors;
7176 		int new_data_disks;
7177 
7178 		if (journal_dev) {
7179 			pr_warn("md/raid:%s: don't support reshape with journal - aborting.\n",
7180 				mdname(mddev));
7181 			return -EINVAL;
7182 		}
7183 
7184 		if (mddev->new_level != mddev->level) {
7185 			pr_warn("md/raid:%s: unsupported reshape required - aborting.\n",
7186 				mdname(mddev));
7187 			return -EINVAL;
7188 		}
7189 		old_disks = mddev->raid_disks - mddev->delta_disks;
7190 		/* reshape_position must be on a new-stripe boundary, and one
7191 		 * further up in new geometry must map after here in old
7192 		 * geometry.
7193 		 * If the chunk sizes are different, then as we perform reshape
7194 		 * in units of the largest of the two, reshape_position needs
7195 		 * be a multiple of the largest chunk size times new data disks.
7196 		 */
7197 		here_new = mddev->reshape_position;
7198 		chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
7199 		new_data_disks = mddev->raid_disks - max_degraded;
7200 		if (sector_div(here_new, chunk_sectors * new_data_disks)) {
7201 			pr_warn("md/raid:%s: reshape_position not on a stripe boundary\n",
7202 				mdname(mddev));
7203 			return -EINVAL;
7204 		}
7205 		reshape_offset = here_new * chunk_sectors;
7206 		/* here_new is the stripe we will write to */
7207 		here_old = mddev->reshape_position;
7208 		sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
7209 		/* here_old is the first stripe that we might need to read
7210 		 * from */
7211 		if (mddev->delta_disks == 0) {
7212 			/* We cannot be sure it is safe to start an in-place
7213 			 * reshape.  It is only safe if user-space is monitoring
7214 			 * and taking constant backups.
7215 			 * mdadm always starts a situation like this in
7216 			 * readonly mode so it can take control before
7217 			 * allowing any writes.  So just check for that.
7218 			 */
7219 			if (abs(min_offset_diff) >= mddev->chunk_sectors &&
7220 			    abs(min_offset_diff) >= mddev->new_chunk_sectors)
7221 				/* not really in-place - so OK */;
7222 			else if (mddev->ro == 0) {
7223 				pr_warn("md/raid:%s: in-place reshape must be started in read-only mode - aborting\n",
7224 					mdname(mddev));
7225 				return -EINVAL;
7226 			}
7227 		} else if (mddev->reshape_backwards
7228 		    ? (here_new * chunk_sectors + min_offset_diff <=
7229 		       here_old * chunk_sectors)
7230 		    : (here_new * chunk_sectors >=
7231 		       here_old * chunk_sectors + (-min_offset_diff))) {
7232 			/* Reading from the same stripe as writing to - bad */
7233 			pr_warn("md/raid:%s: reshape_position too early for auto-recovery - aborting.\n",
7234 				mdname(mddev));
7235 			return -EINVAL;
7236 		}
7237 		pr_debug("md/raid:%s: reshape will continue\n", mdname(mddev));
7238 		/* OK, we should be able to continue; */
7239 	} else {
7240 		BUG_ON(mddev->level != mddev->new_level);
7241 		BUG_ON(mddev->layout != mddev->new_layout);
7242 		BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
7243 		BUG_ON(mddev->delta_disks != 0);
7244 	}
7245 
7246 	if (test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
7247 	    test_bit(MD_HAS_PPL, &mddev->flags)) {
7248 		pr_warn("md/raid:%s: using journal device and PPL not allowed - disabling PPL\n",
7249 			mdname(mddev));
7250 		clear_bit(MD_HAS_PPL, &mddev->flags);
7251 		clear_bit(MD_HAS_MULTIPLE_PPLS, &mddev->flags);
7252 	}
7253 
7254 	if (mddev->private == NULL)
7255 		conf = setup_conf(mddev);
7256 	else
7257 		conf = mddev->private;
7258 
7259 	if (IS_ERR(conf))
7260 		return PTR_ERR(conf);
7261 
7262 	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
7263 		if (!journal_dev) {
7264 			pr_warn("md/raid:%s: journal disk is missing, force array readonly\n",
7265 				mdname(mddev));
7266 			mddev->ro = 1;
7267 			set_disk_ro(mddev->gendisk, 1);
7268 		} else if (mddev->recovery_cp == MaxSector)
7269 			set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
7270 	}
7271 
7272 	conf->min_offset_diff = min_offset_diff;
7273 	mddev->thread = conf->thread;
7274 	conf->thread = NULL;
7275 	mddev->private = conf;
7276 
7277 	for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
7278 	     i++) {
7279 		rdev = conf->disks[i].rdev;
7280 		if (!rdev && conf->disks[i].replacement) {
7281 			/* The replacement is all we have yet */
7282 			rdev = conf->disks[i].replacement;
7283 			conf->disks[i].replacement = NULL;
7284 			clear_bit(Replacement, &rdev->flags);
7285 			conf->disks[i].rdev = rdev;
7286 		}
7287 		if (!rdev)
7288 			continue;
7289 		if (conf->disks[i].replacement &&
7290 		    conf->reshape_progress != MaxSector) {
7291 			/* replacements and reshape simply do not mix. */
7292 			pr_warn("md: cannot handle concurrent replacement and reshape.\n");
7293 			goto abort;
7294 		}
7295 		if (test_bit(In_sync, &rdev->flags)) {
7296 			working_disks++;
7297 			continue;
7298 		}
7299 		/* This disc is not fully in-sync.  However if it
7300 		 * just stored parity (beyond the recovery_offset),
7301 		 * when we don't need to be concerned about the
7302 		 * array being dirty.
7303 		 * When reshape goes 'backwards', we never have
7304 		 * partially completed devices, so we only need
7305 		 * to worry about reshape going forwards.
7306 		 */
7307 		/* Hack because v0.91 doesn't store recovery_offset properly. */
7308 		if (mddev->major_version == 0 &&
7309 		    mddev->minor_version > 90)
7310 			rdev->recovery_offset = reshape_offset;
7311 
7312 		if (rdev->recovery_offset < reshape_offset) {
7313 			/* We need to check old and new layout */
7314 			if (!only_parity(rdev->raid_disk,
7315 					 conf->algorithm,
7316 					 conf->raid_disks,
7317 					 conf->max_degraded))
7318 				continue;
7319 		}
7320 		if (!only_parity(rdev->raid_disk,
7321 				 conf->prev_algo,
7322 				 conf->previous_raid_disks,
7323 				 conf->max_degraded))
7324 			continue;
7325 		dirty_parity_disks++;
7326 	}
7327 
7328 	/*
7329 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
7330 	 */
7331 	mddev->degraded = raid5_calc_degraded(conf);
7332 
7333 	if (has_failed(conf)) {
7334 		pr_crit("md/raid:%s: not enough operational devices (%d/%d failed)\n",
7335 			mdname(mddev), mddev->degraded, conf->raid_disks);
7336 		goto abort;
7337 	}
7338 
7339 	/* device size must be a multiple of chunk size */
7340 	mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
7341 	mddev->resync_max_sectors = mddev->dev_sectors;
7342 
7343 	if (mddev->degraded > dirty_parity_disks &&
7344 	    mddev->recovery_cp != MaxSector) {
7345 		if (test_bit(MD_HAS_PPL, &mddev->flags))
7346 			pr_crit("md/raid:%s: starting dirty degraded array with PPL.\n",
7347 				mdname(mddev));
7348 		else if (mddev->ok_start_degraded)
7349 			pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
7350 				mdname(mddev));
7351 		else {
7352 			pr_crit("md/raid:%s: cannot start dirty degraded array.\n",
7353 				mdname(mddev));
7354 			goto abort;
7355 		}
7356 	}
7357 
7358 	pr_info("md/raid:%s: raid level %d active with %d out of %d devices, algorithm %d\n",
7359 		mdname(mddev), conf->level,
7360 		mddev->raid_disks-mddev->degraded, mddev->raid_disks,
7361 		mddev->new_layout);
7362 
7363 	print_raid5_conf(conf);
7364 
7365 	if (conf->reshape_progress != MaxSector) {
7366 		conf->reshape_safe = conf->reshape_progress;
7367 		atomic_set(&conf->reshape_stripes, 0);
7368 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7369 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7370 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7371 		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7372 		mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7373 							"reshape");
7374 	}
7375 
7376 	/* Ok, everything is just fine now */
7377 	if (mddev->to_remove == &raid5_attrs_group)
7378 		mddev->to_remove = NULL;
7379 	else if (mddev->kobj.sd &&
7380 	    sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
7381 		pr_warn("raid5: failed to create sysfs attributes for %s\n",
7382 			mdname(mddev));
7383 	md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7384 
7385 	if (mddev->queue) {
7386 		int chunk_size;
7387 		/* read-ahead size must cover two whole stripes, which
7388 		 * is 2 * (datadisks) * chunksize where 'n' is the
7389 		 * number of raid devices
7390 		 */
7391 		int data_disks = conf->previous_raid_disks - conf->max_degraded;
7392 		int stripe = data_disks *
7393 			((mddev->chunk_sectors << 9) / PAGE_SIZE);
7394 		if (mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7395 			mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7396 
7397 		chunk_size = mddev->chunk_sectors << 9;
7398 		blk_queue_io_min(mddev->queue, chunk_size);
7399 		blk_queue_io_opt(mddev->queue, chunk_size *
7400 				 (conf->raid_disks - conf->max_degraded));
7401 		mddev->queue->limits.raid_partial_stripes_expensive = 1;
7402 		/*
7403 		 * We can only discard a whole stripe. It doesn't make sense to
7404 		 * discard data disk but write parity disk
7405 		 */
7406 		stripe = stripe * PAGE_SIZE;
7407 		/* Round up to power of 2, as discard handling
7408 		 * currently assumes that */
7409 		while ((stripe-1) & stripe)
7410 			stripe = (stripe | (stripe-1)) + 1;
7411 		mddev->queue->limits.discard_alignment = stripe;
7412 		mddev->queue->limits.discard_granularity = stripe;
7413 
7414 		blk_queue_max_write_same_sectors(mddev->queue, 0);
7415 		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
7416 
7417 		rdev_for_each(rdev, mddev) {
7418 			disk_stack_limits(mddev->gendisk, rdev->bdev,
7419 					  rdev->data_offset << 9);
7420 			disk_stack_limits(mddev->gendisk, rdev->bdev,
7421 					  rdev->new_data_offset << 9);
7422 		}
7423 
7424 		/*
7425 		 * zeroing is required, otherwise data
7426 		 * could be lost. Consider a scenario: discard a stripe
7427 		 * (the stripe could be inconsistent if
7428 		 * discard_zeroes_data is 0); write one disk of the
7429 		 * stripe (the stripe could be inconsistent again
7430 		 * depending on which disks are used to calculate
7431 		 * parity); the disk is broken; The stripe data of this
7432 		 * disk is lost.
7433 		 *
7434 		 * We only allow DISCARD if the sysadmin has confirmed that
7435 		 * only safe devices are in use by setting a module parameter.
7436 		 * A better idea might be to turn DISCARD into WRITE_ZEROES
7437 		 * requests, as that is required to be safe.
7438 		 */
7439 		if (devices_handle_discard_safely &&
7440 		    mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
7441 		    mddev->queue->limits.discard_granularity >= stripe)
7442 			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
7443 						mddev->queue);
7444 		else
7445 			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
7446 						mddev->queue);
7447 
7448 		blk_queue_max_hw_sectors(mddev->queue, UINT_MAX);
7449 	}
7450 
7451 	if (log_init(conf, journal_dev, raid5_has_ppl(conf)))
7452 		goto abort;
7453 
7454 	return 0;
7455 abort:
7456 	md_unregister_thread(&mddev->thread);
7457 	print_raid5_conf(conf);
7458 	free_conf(conf);
7459 	mddev->private = NULL;
7460 	pr_warn("md/raid:%s: failed to run raid set.\n", mdname(mddev));
7461 	return -EIO;
7462 }
7463 
7464 static void raid5_free(struct mddev *mddev, void *priv)
7465 {
7466 	struct r5conf *conf = priv;
7467 
7468 	free_conf(conf);
7469 	mddev->to_remove = &raid5_attrs_group;
7470 }
7471 
7472 static void raid5_status(struct seq_file *seq, struct mddev *mddev)
7473 {
7474 	struct r5conf *conf = mddev->private;
7475 	int i;
7476 
7477 	seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
7478 		conf->chunk_sectors / 2, mddev->layout);
7479 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
7480 	rcu_read_lock();
7481 	for (i = 0; i < conf->raid_disks; i++) {
7482 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
7483 		seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
7484 	}
7485 	rcu_read_unlock();
7486 	seq_printf (seq, "]");
7487 }
7488 
7489 static void print_raid5_conf (struct r5conf *conf)
7490 {
7491 	int i;
7492 	struct disk_info *tmp;
7493 
7494 	pr_debug("RAID conf printout:\n");
7495 	if (!conf) {
7496 		pr_debug("(conf==NULL)\n");
7497 		return;
7498 	}
7499 	pr_debug(" --- level:%d rd:%d wd:%d\n", conf->level,
7500 	       conf->raid_disks,
7501 	       conf->raid_disks - conf->mddev->degraded);
7502 
7503 	for (i = 0; i < conf->raid_disks; i++) {
7504 		char b[BDEVNAME_SIZE];
7505 		tmp = conf->disks + i;
7506 		if (tmp->rdev)
7507 			pr_debug(" disk %d, o:%d, dev:%s\n",
7508 			       i, !test_bit(Faulty, &tmp->rdev->flags),
7509 			       bdevname(tmp->rdev->bdev, b));
7510 	}
7511 }
7512 
7513 static int raid5_spare_active(struct mddev *mddev)
7514 {
7515 	int i;
7516 	struct r5conf *conf = mddev->private;
7517 	struct disk_info *tmp;
7518 	int count = 0;
7519 	unsigned long flags;
7520 
7521 	for (i = 0; i < conf->raid_disks; i++) {
7522 		tmp = conf->disks + i;
7523 		if (tmp->replacement
7524 		    && tmp->replacement->recovery_offset == MaxSector
7525 		    && !test_bit(Faulty, &tmp->replacement->flags)
7526 		    && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7527 			/* Replacement has just become active. */
7528 			if (!tmp->rdev
7529 			    || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7530 				count++;
7531 			if (tmp->rdev) {
7532 				/* Replaced device not technically faulty,
7533 				 * but we need to be sure it gets removed
7534 				 * and never re-added.
7535 				 */
7536 				set_bit(Faulty, &tmp->rdev->flags);
7537 				sysfs_notify_dirent_safe(
7538 					tmp->rdev->sysfs_state);
7539 			}
7540 			sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7541 		} else if (tmp->rdev
7542 		    && tmp->rdev->recovery_offset == MaxSector
7543 		    && !test_bit(Faulty, &tmp->rdev->flags)
7544 		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7545 			count++;
7546 			sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7547 		}
7548 	}
7549 	spin_lock_irqsave(&conf->device_lock, flags);
7550 	mddev->degraded = raid5_calc_degraded(conf);
7551 	spin_unlock_irqrestore(&conf->device_lock, flags);
7552 	print_raid5_conf(conf);
7553 	return count;
7554 }
7555 
7556 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7557 {
7558 	struct r5conf *conf = mddev->private;
7559 	int err = 0;
7560 	int number = rdev->raid_disk;
7561 	struct md_rdev **rdevp;
7562 	struct disk_info *p = conf->disks + number;
7563 
7564 	print_raid5_conf(conf);
7565 	if (test_bit(Journal, &rdev->flags) && conf->log) {
7566 		/*
7567 		 * we can't wait pending write here, as this is called in
7568 		 * raid5d, wait will deadlock.
7569 		 * neilb: there is no locking about new writes here,
7570 		 * so this cannot be safe.
7571 		 */
7572 		if (atomic_read(&conf->active_stripes) ||
7573 		    atomic_read(&conf->r5c_cached_full_stripes) ||
7574 		    atomic_read(&conf->r5c_cached_partial_stripes)) {
7575 			return -EBUSY;
7576 		}
7577 		log_exit(conf);
7578 		return 0;
7579 	}
7580 	if (rdev == p->rdev)
7581 		rdevp = &p->rdev;
7582 	else if (rdev == p->replacement)
7583 		rdevp = &p->replacement;
7584 	else
7585 		return 0;
7586 
7587 	if (number >= conf->raid_disks &&
7588 	    conf->reshape_progress == MaxSector)
7589 		clear_bit(In_sync, &rdev->flags);
7590 
7591 	if (test_bit(In_sync, &rdev->flags) ||
7592 	    atomic_read(&rdev->nr_pending)) {
7593 		err = -EBUSY;
7594 		goto abort;
7595 	}
7596 	/* Only remove non-faulty devices if recovery
7597 	 * isn't possible.
7598 	 */
7599 	if (!test_bit(Faulty, &rdev->flags) &&
7600 	    mddev->recovery_disabled != conf->recovery_disabled &&
7601 	    !has_failed(conf) &&
7602 	    (!p->replacement || p->replacement == rdev) &&
7603 	    number < conf->raid_disks) {
7604 		err = -EBUSY;
7605 		goto abort;
7606 	}
7607 	*rdevp = NULL;
7608 	if (!test_bit(RemoveSynchronized, &rdev->flags)) {
7609 		synchronize_rcu();
7610 		if (atomic_read(&rdev->nr_pending)) {
7611 			/* lost the race, try later */
7612 			err = -EBUSY;
7613 			*rdevp = rdev;
7614 		}
7615 	}
7616 	if (!err) {
7617 		err = log_modify(conf, rdev, false);
7618 		if (err)
7619 			goto abort;
7620 	}
7621 	if (p->replacement) {
7622 		/* We must have just cleared 'rdev' */
7623 		p->rdev = p->replacement;
7624 		clear_bit(Replacement, &p->replacement->flags);
7625 		smp_mb(); /* Make sure other CPUs may see both as identical
7626 			   * but will never see neither - if they are careful
7627 			   */
7628 		p->replacement = NULL;
7629 
7630 		if (!err)
7631 			err = log_modify(conf, p->rdev, true);
7632 	}
7633 
7634 	clear_bit(WantReplacement, &rdev->flags);
7635 abort:
7636 
7637 	print_raid5_conf(conf);
7638 	return err;
7639 }
7640 
7641 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7642 {
7643 	struct r5conf *conf = mddev->private;
7644 	int err = -EEXIST;
7645 	int disk;
7646 	struct disk_info *p;
7647 	int first = 0;
7648 	int last = conf->raid_disks - 1;
7649 
7650 	if (test_bit(Journal, &rdev->flags)) {
7651 		if (conf->log)
7652 			return -EBUSY;
7653 
7654 		rdev->raid_disk = 0;
7655 		/*
7656 		 * The array is in readonly mode if journal is missing, so no
7657 		 * write requests running. We should be safe
7658 		 */
7659 		log_init(conf, rdev, false);
7660 		return 0;
7661 	}
7662 	if (mddev->recovery_disabled == conf->recovery_disabled)
7663 		return -EBUSY;
7664 
7665 	if (rdev->saved_raid_disk < 0 && has_failed(conf))
7666 		/* no point adding a device */
7667 		return -EINVAL;
7668 
7669 	if (rdev->raid_disk >= 0)
7670 		first = last = rdev->raid_disk;
7671 
7672 	/*
7673 	 * find the disk ... but prefer rdev->saved_raid_disk
7674 	 * if possible.
7675 	 */
7676 	if (rdev->saved_raid_disk >= 0 &&
7677 	    rdev->saved_raid_disk >= first &&
7678 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
7679 		first = rdev->saved_raid_disk;
7680 
7681 	for (disk = first; disk <= last; disk++) {
7682 		p = conf->disks + disk;
7683 		if (p->rdev == NULL) {
7684 			clear_bit(In_sync, &rdev->flags);
7685 			rdev->raid_disk = disk;
7686 			if (rdev->saved_raid_disk != disk)
7687 				conf->fullsync = 1;
7688 			rcu_assign_pointer(p->rdev, rdev);
7689 
7690 			err = log_modify(conf, rdev, true);
7691 
7692 			goto out;
7693 		}
7694 	}
7695 	for (disk = first; disk <= last; disk++) {
7696 		p = conf->disks + disk;
7697 		if (test_bit(WantReplacement, &p->rdev->flags) &&
7698 		    p->replacement == NULL) {
7699 			clear_bit(In_sync, &rdev->flags);
7700 			set_bit(Replacement, &rdev->flags);
7701 			rdev->raid_disk = disk;
7702 			err = 0;
7703 			conf->fullsync = 1;
7704 			rcu_assign_pointer(p->replacement, rdev);
7705 			break;
7706 		}
7707 	}
7708 out:
7709 	print_raid5_conf(conf);
7710 	return err;
7711 }
7712 
7713 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7714 {
7715 	/* no resync is happening, and there is enough space
7716 	 * on all devices, so we can resize.
7717 	 * We need to make sure resync covers any new space.
7718 	 * If the array is shrinking we should possibly wait until
7719 	 * any io in the removed space completes, but it hardly seems
7720 	 * worth it.
7721 	 */
7722 	sector_t newsize;
7723 	struct r5conf *conf = mddev->private;
7724 
7725 	if (conf->log || raid5_has_ppl(conf))
7726 		return -EINVAL;
7727 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
7728 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7729 	if (mddev->external_size &&
7730 	    mddev->array_sectors > newsize)
7731 		return -EINVAL;
7732 	if (mddev->bitmap) {
7733 		int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7734 		if (ret)
7735 			return ret;
7736 	}
7737 	md_set_array_sectors(mddev, newsize);
7738 	if (sectors > mddev->dev_sectors &&
7739 	    mddev->recovery_cp > mddev->dev_sectors) {
7740 		mddev->recovery_cp = mddev->dev_sectors;
7741 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7742 	}
7743 	mddev->dev_sectors = sectors;
7744 	mddev->resync_max_sectors = sectors;
7745 	return 0;
7746 }
7747 
7748 static int check_stripe_cache(struct mddev *mddev)
7749 {
7750 	/* Can only proceed if there are plenty of stripe_heads.
7751 	 * We need a minimum of one full stripe,, and for sensible progress
7752 	 * it is best to have about 4 times that.
7753 	 * If we require 4 times, then the default 256 4K stripe_heads will
7754 	 * allow for chunk sizes up to 256K, which is probably OK.
7755 	 * If the chunk size is greater, user-space should request more
7756 	 * stripe_heads first.
7757 	 */
7758 	struct r5conf *conf = mddev->private;
7759 	if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7760 	    > conf->min_nr_stripes ||
7761 	    ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7762 	    > conf->min_nr_stripes) {
7763 		pr_warn("md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7764 			mdname(mddev),
7765 			((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7766 			 / STRIPE_SIZE)*4);
7767 		return 0;
7768 	}
7769 	return 1;
7770 }
7771 
7772 static int check_reshape(struct mddev *mddev)
7773 {
7774 	struct r5conf *conf = mddev->private;
7775 
7776 	if (conf->log || raid5_has_ppl(conf))
7777 		return -EINVAL;
7778 	if (mddev->delta_disks == 0 &&
7779 	    mddev->new_layout == mddev->layout &&
7780 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
7781 		return 0; /* nothing to do */
7782 	if (has_failed(conf))
7783 		return -EINVAL;
7784 	if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7785 		/* We might be able to shrink, but the devices must
7786 		 * be made bigger first.
7787 		 * For raid6, 4 is the minimum size.
7788 		 * Otherwise 2 is the minimum
7789 		 */
7790 		int min = 2;
7791 		if (mddev->level == 6)
7792 			min = 4;
7793 		if (mddev->raid_disks + mddev->delta_disks < min)
7794 			return -EINVAL;
7795 	}
7796 
7797 	if (!check_stripe_cache(mddev))
7798 		return -ENOSPC;
7799 
7800 	if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7801 	    mddev->delta_disks > 0)
7802 		if (resize_chunks(conf,
7803 				  conf->previous_raid_disks
7804 				  + max(0, mddev->delta_disks),
7805 				  max(mddev->new_chunk_sectors,
7806 				      mddev->chunk_sectors)
7807 			    ) < 0)
7808 			return -ENOMEM;
7809 
7810 	if (conf->previous_raid_disks + mddev->delta_disks <= conf->pool_size)
7811 		return 0; /* never bother to shrink */
7812 	return resize_stripes(conf, (conf->previous_raid_disks
7813 				     + mddev->delta_disks));
7814 }
7815 
7816 static int raid5_start_reshape(struct mddev *mddev)
7817 {
7818 	struct r5conf *conf = mddev->private;
7819 	struct md_rdev *rdev;
7820 	int spares = 0;
7821 	unsigned long flags;
7822 
7823 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7824 		return -EBUSY;
7825 
7826 	if (!check_stripe_cache(mddev))
7827 		return -ENOSPC;
7828 
7829 	if (has_failed(conf))
7830 		return -EINVAL;
7831 
7832 	rdev_for_each(rdev, mddev) {
7833 		if (!test_bit(In_sync, &rdev->flags)
7834 		    && !test_bit(Faulty, &rdev->flags))
7835 			spares++;
7836 	}
7837 
7838 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7839 		/* Not enough devices even to make a degraded array
7840 		 * of that size
7841 		 */
7842 		return -EINVAL;
7843 
7844 	/* Refuse to reduce size of the array.  Any reductions in
7845 	 * array size must be through explicit setting of array_size
7846 	 * attribute.
7847 	 */
7848 	if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7849 	    < mddev->array_sectors) {
7850 		pr_warn("md/raid:%s: array size must be reduced before number of disks\n",
7851 			mdname(mddev));
7852 		return -EINVAL;
7853 	}
7854 
7855 	atomic_set(&conf->reshape_stripes, 0);
7856 	spin_lock_irq(&conf->device_lock);
7857 	write_seqcount_begin(&conf->gen_lock);
7858 	conf->previous_raid_disks = conf->raid_disks;
7859 	conf->raid_disks += mddev->delta_disks;
7860 	conf->prev_chunk_sectors = conf->chunk_sectors;
7861 	conf->chunk_sectors = mddev->new_chunk_sectors;
7862 	conf->prev_algo = conf->algorithm;
7863 	conf->algorithm = mddev->new_layout;
7864 	conf->generation++;
7865 	/* Code that selects data_offset needs to see the generation update
7866 	 * if reshape_progress has been set - so a memory barrier needed.
7867 	 */
7868 	smp_mb();
7869 	if (mddev->reshape_backwards)
7870 		conf->reshape_progress = raid5_size(mddev, 0, 0);
7871 	else
7872 		conf->reshape_progress = 0;
7873 	conf->reshape_safe = conf->reshape_progress;
7874 	write_seqcount_end(&conf->gen_lock);
7875 	spin_unlock_irq(&conf->device_lock);
7876 
7877 	/* Now make sure any requests that proceeded on the assumption
7878 	 * the reshape wasn't running - like Discard or Read - have
7879 	 * completed.
7880 	 */
7881 	mddev_suspend(mddev);
7882 	mddev_resume(mddev);
7883 
7884 	/* Add some new drives, as many as will fit.
7885 	 * We know there are enough to make the newly sized array work.
7886 	 * Don't add devices if we are reducing the number of
7887 	 * devices in the array.  This is because it is not possible
7888 	 * to correctly record the "partially reconstructed" state of
7889 	 * such devices during the reshape and confusion could result.
7890 	 */
7891 	if (mddev->delta_disks >= 0) {
7892 		rdev_for_each(rdev, mddev)
7893 			if (rdev->raid_disk < 0 &&
7894 			    !test_bit(Faulty, &rdev->flags)) {
7895 				if (raid5_add_disk(mddev, rdev) == 0) {
7896 					if (rdev->raid_disk
7897 					    >= conf->previous_raid_disks)
7898 						set_bit(In_sync, &rdev->flags);
7899 					else
7900 						rdev->recovery_offset = 0;
7901 
7902 					if (sysfs_link_rdev(mddev, rdev))
7903 						/* Failure here is OK */;
7904 				}
7905 			} else if (rdev->raid_disk >= conf->previous_raid_disks
7906 				   && !test_bit(Faulty, &rdev->flags)) {
7907 				/* This is a spare that was manually added */
7908 				set_bit(In_sync, &rdev->flags);
7909 			}
7910 
7911 		/* When a reshape changes the number of devices,
7912 		 * ->degraded is measured against the larger of the
7913 		 * pre and post number of devices.
7914 		 */
7915 		spin_lock_irqsave(&conf->device_lock, flags);
7916 		mddev->degraded = raid5_calc_degraded(conf);
7917 		spin_unlock_irqrestore(&conf->device_lock, flags);
7918 	}
7919 	mddev->raid_disks = conf->raid_disks;
7920 	mddev->reshape_position = conf->reshape_progress;
7921 	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
7922 
7923 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7924 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7925 	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7926 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7927 	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7928 	mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7929 						"reshape");
7930 	if (!mddev->sync_thread) {
7931 		mddev->recovery = 0;
7932 		spin_lock_irq(&conf->device_lock);
7933 		write_seqcount_begin(&conf->gen_lock);
7934 		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7935 		mddev->new_chunk_sectors =
7936 			conf->chunk_sectors = conf->prev_chunk_sectors;
7937 		mddev->new_layout = conf->algorithm = conf->prev_algo;
7938 		rdev_for_each(rdev, mddev)
7939 			rdev->new_data_offset = rdev->data_offset;
7940 		smp_wmb();
7941 		conf->generation --;
7942 		conf->reshape_progress = MaxSector;
7943 		mddev->reshape_position = MaxSector;
7944 		write_seqcount_end(&conf->gen_lock);
7945 		spin_unlock_irq(&conf->device_lock);
7946 		return -EAGAIN;
7947 	}
7948 	conf->reshape_checkpoint = jiffies;
7949 	md_wakeup_thread(mddev->sync_thread);
7950 	md_new_event(mddev);
7951 	return 0;
7952 }
7953 
7954 /* This is called from the reshape thread and should make any
7955  * changes needed in 'conf'
7956  */
7957 static void end_reshape(struct r5conf *conf)
7958 {
7959 
7960 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7961 
7962 		spin_lock_irq(&conf->device_lock);
7963 		conf->previous_raid_disks = conf->raid_disks;
7964 		md_finish_reshape(conf->mddev);
7965 		smp_wmb();
7966 		conf->reshape_progress = MaxSector;
7967 		conf->mddev->reshape_position = MaxSector;
7968 		spin_unlock_irq(&conf->device_lock);
7969 		wake_up(&conf->wait_for_overlap);
7970 
7971 		/* read-ahead size must cover two whole stripes, which is
7972 		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7973 		 */
7974 		if (conf->mddev->queue) {
7975 			int data_disks = conf->raid_disks - conf->max_degraded;
7976 			int stripe = data_disks * ((conf->chunk_sectors << 9)
7977 						   / PAGE_SIZE);
7978 			if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7979 				conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7980 		}
7981 	}
7982 }
7983 
7984 /* This is called from the raid5d thread with mddev_lock held.
7985  * It makes config changes to the device.
7986  */
7987 static void raid5_finish_reshape(struct mddev *mddev)
7988 {
7989 	struct r5conf *conf = mddev->private;
7990 
7991 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7992 
7993 		if (mddev->delta_disks > 0) {
7994 			md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7995 			if (mddev->queue) {
7996 				set_capacity(mddev->gendisk, mddev->array_sectors);
7997 				revalidate_disk(mddev->gendisk);
7998 			}
7999 		} else {
8000 			int d;
8001 			spin_lock_irq(&conf->device_lock);
8002 			mddev->degraded = raid5_calc_degraded(conf);
8003 			spin_unlock_irq(&conf->device_lock);
8004 			for (d = conf->raid_disks ;
8005 			     d < conf->raid_disks - mddev->delta_disks;
8006 			     d++) {
8007 				struct md_rdev *rdev = conf->disks[d].rdev;
8008 				if (rdev)
8009 					clear_bit(In_sync, &rdev->flags);
8010 				rdev = conf->disks[d].replacement;
8011 				if (rdev)
8012 					clear_bit(In_sync, &rdev->flags);
8013 			}
8014 		}
8015 		mddev->layout = conf->algorithm;
8016 		mddev->chunk_sectors = conf->chunk_sectors;
8017 		mddev->reshape_position = MaxSector;
8018 		mddev->delta_disks = 0;
8019 		mddev->reshape_backwards = 0;
8020 	}
8021 }
8022 
8023 static void raid5_quiesce(struct mddev *mddev, int state)
8024 {
8025 	struct r5conf *conf = mddev->private;
8026 
8027 	switch(state) {
8028 	case 2: /* resume for a suspend */
8029 		wake_up(&conf->wait_for_overlap);
8030 		break;
8031 
8032 	case 1: /* stop all writes */
8033 		lock_all_device_hash_locks_irq(conf);
8034 		/* '2' tells resync/reshape to pause so that all
8035 		 * active stripes can drain
8036 		 */
8037 		r5c_flush_cache(conf, INT_MAX);
8038 		conf->quiesce = 2;
8039 		wait_event_cmd(conf->wait_for_quiescent,
8040 				    atomic_read(&conf->active_stripes) == 0 &&
8041 				    atomic_read(&conf->active_aligned_reads) == 0,
8042 				    unlock_all_device_hash_locks_irq(conf),
8043 				    lock_all_device_hash_locks_irq(conf));
8044 		conf->quiesce = 1;
8045 		unlock_all_device_hash_locks_irq(conf);
8046 		/* allow reshape to continue */
8047 		wake_up(&conf->wait_for_overlap);
8048 		break;
8049 
8050 	case 0: /* re-enable writes */
8051 		lock_all_device_hash_locks_irq(conf);
8052 		conf->quiesce = 0;
8053 		wake_up(&conf->wait_for_quiescent);
8054 		wake_up(&conf->wait_for_overlap);
8055 		unlock_all_device_hash_locks_irq(conf);
8056 		break;
8057 	}
8058 	r5l_quiesce(conf->log, state);
8059 }
8060 
8061 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
8062 {
8063 	struct r0conf *raid0_conf = mddev->private;
8064 	sector_t sectors;
8065 
8066 	/* for raid0 takeover only one zone is supported */
8067 	if (raid0_conf->nr_strip_zones > 1) {
8068 		pr_warn("md/raid:%s: cannot takeover raid0 with more than one zone.\n",
8069 			mdname(mddev));
8070 		return ERR_PTR(-EINVAL);
8071 	}
8072 
8073 	sectors = raid0_conf->strip_zone[0].zone_end;
8074 	sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
8075 	mddev->dev_sectors = sectors;
8076 	mddev->new_level = level;
8077 	mddev->new_layout = ALGORITHM_PARITY_N;
8078 	mddev->new_chunk_sectors = mddev->chunk_sectors;
8079 	mddev->raid_disks += 1;
8080 	mddev->delta_disks = 1;
8081 	/* make sure it will be not marked as dirty */
8082 	mddev->recovery_cp = MaxSector;
8083 
8084 	return setup_conf(mddev);
8085 }
8086 
8087 static void *raid5_takeover_raid1(struct mddev *mddev)
8088 {
8089 	int chunksect;
8090 	void *ret;
8091 
8092 	if (mddev->raid_disks != 2 ||
8093 	    mddev->degraded > 1)
8094 		return ERR_PTR(-EINVAL);
8095 
8096 	/* Should check if there are write-behind devices? */
8097 
8098 	chunksect = 64*2; /* 64K by default */
8099 
8100 	/* The array must be an exact multiple of chunksize */
8101 	while (chunksect && (mddev->array_sectors & (chunksect-1)))
8102 		chunksect >>= 1;
8103 
8104 	if ((chunksect<<9) < STRIPE_SIZE)
8105 		/* array size does not allow a suitable chunk size */
8106 		return ERR_PTR(-EINVAL);
8107 
8108 	mddev->new_level = 5;
8109 	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
8110 	mddev->new_chunk_sectors = chunksect;
8111 
8112 	ret = setup_conf(mddev);
8113 	if (!IS_ERR(ret))
8114 		mddev_clear_unsupported_flags(mddev,
8115 			UNSUPPORTED_MDDEV_FLAGS);
8116 	return ret;
8117 }
8118 
8119 static void *raid5_takeover_raid6(struct mddev *mddev)
8120 {
8121 	int new_layout;
8122 
8123 	switch (mddev->layout) {
8124 	case ALGORITHM_LEFT_ASYMMETRIC_6:
8125 		new_layout = ALGORITHM_LEFT_ASYMMETRIC;
8126 		break;
8127 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
8128 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
8129 		break;
8130 	case ALGORITHM_LEFT_SYMMETRIC_6:
8131 		new_layout = ALGORITHM_LEFT_SYMMETRIC;
8132 		break;
8133 	case ALGORITHM_RIGHT_SYMMETRIC_6:
8134 		new_layout = ALGORITHM_RIGHT_SYMMETRIC;
8135 		break;
8136 	case ALGORITHM_PARITY_0_6:
8137 		new_layout = ALGORITHM_PARITY_0;
8138 		break;
8139 	case ALGORITHM_PARITY_N:
8140 		new_layout = ALGORITHM_PARITY_N;
8141 		break;
8142 	default:
8143 		return ERR_PTR(-EINVAL);
8144 	}
8145 	mddev->new_level = 5;
8146 	mddev->new_layout = new_layout;
8147 	mddev->delta_disks = -1;
8148 	mddev->raid_disks -= 1;
8149 	return setup_conf(mddev);
8150 }
8151 
8152 static int raid5_check_reshape(struct mddev *mddev)
8153 {
8154 	/* For a 2-drive array, the layout and chunk size can be changed
8155 	 * immediately as not restriping is needed.
8156 	 * For larger arrays we record the new value - after validation
8157 	 * to be used by a reshape pass.
8158 	 */
8159 	struct r5conf *conf = mddev->private;
8160 	int new_chunk = mddev->new_chunk_sectors;
8161 
8162 	if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
8163 		return -EINVAL;
8164 	if (new_chunk > 0) {
8165 		if (!is_power_of_2(new_chunk))
8166 			return -EINVAL;
8167 		if (new_chunk < (PAGE_SIZE>>9))
8168 			return -EINVAL;
8169 		if (mddev->array_sectors & (new_chunk-1))
8170 			/* not factor of array size */
8171 			return -EINVAL;
8172 	}
8173 
8174 	/* They look valid */
8175 
8176 	if (mddev->raid_disks == 2) {
8177 		/* can make the change immediately */
8178 		if (mddev->new_layout >= 0) {
8179 			conf->algorithm = mddev->new_layout;
8180 			mddev->layout = mddev->new_layout;
8181 		}
8182 		if (new_chunk > 0) {
8183 			conf->chunk_sectors = new_chunk ;
8184 			mddev->chunk_sectors = new_chunk;
8185 		}
8186 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
8187 		md_wakeup_thread(mddev->thread);
8188 	}
8189 	return check_reshape(mddev);
8190 }
8191 
8192 static int raid6_check_reshape(struct mddev *mddev)
8193 {
8194 	int new_chunk = mddev->new_chunk_sectors;
8195 
8196 	if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
8197 		return -EINVAL;
8198 	if (new_chunk > 0) {
8199 		if (!is_power_of_2(new_chunk))
8200 			return -EINVAL;
8201 		if (new_chunk < (PAGE_SIZE >> 9))
8202 			return -EINVAL;
8203 		if (mddev->array_sectors & (new_chunk-1))
8204 			/* not factor of array size */
8205 			return -EINVAL;
8206 	}
8207 
8208 	/* They look valid */
8209 	return check_reshape(mddev);
8210 }
8211 
8212 static void *raid5_takeover(struct mddev *mddev)
8213 {
8214 	/* raid5 can take over:
8215 	 *  raid0 - if there is only one strip zone - make it a raid4 layout
8216 	 *  raid1 - if there are two drives.  We need to know the chunk size
8217 	 *  raid4 - trivial - just use a raid4 layout.
8218 	 *  raid6 - Providing it is a *_6 layout
8219 	 */
8220 	if (mddev->level == 0)
8221 		return raid45_takeover_raid0(mddev, 5);
8222 	if (mddev->level == 1)
8223 		return raid5_takeover_raid1(mddev);
8224 	if (mddev->level == 4) {
8225 		mddev->new_layout = ALGORITHM_PARITY_N;
8226 		mddev->new_level = 5;
8227 		return setup_conf(mddev);
8228 	}
8229 	if (mddev->level == 6)
8230 		return raid5_takeover_raid6(mddev);
8231 
8232 	return ERR_PTR(-EINVAL);
8233 }
8234 
8235 static void *raid4_takeover(struct mddev *mddev)
8236 {
8237 	/* raid4 can take over:
8238 	 *  raid0 - if there is only one strip zone
8239 	 *  raid5 - if layout is right
8240 	 */
8241 	if (mddev->level == 0)
8242 		return raid45_takeover_raid0(mddev, 4);
8243 	if (mddev->level == 5 &&
8244 	    mddev->layout == ALGORITHM_PARITY_N) {
8245 		mddev->new_layout = 0;
8246 		mddev->new_level = 4;
8247 		return setup_conf(mddev);
8248 	}
8249 	return ERR_PTR(-EINVAL);
8250 }
8251 
8252 static struct md_personality raid5_personality;
8253 
8254 static void *raid6_takeover(struct mddev *mddev)
8255 {
8256 	/* Currently can only take over a raid5.  We map the
8257 	 * personality to an equivalent raid6 personality
8258 	 * with the Q block at the end.
8259 	 */
8260 	int new_layout;
8261 
8262 	if (mddev->pers != &raid5_personality)
8263 		return ERR_PTR(-EINVAL);
8264 	if (mddev->degraded > 1)
8265 		return ERR_PTR(-EINVAL);
8266 	if (mddev->raid_disks > 253)
8267 		return ERR_PTR(-EINVAL);
8268 	if (mddev->raid_disks < 3)
8269 		return ERR_PTR(-EINVAL);
8270 
8271 	switch (mddev->layout) {
8272 	case ALGORITHM_LEFT_ASYMMETRIC:
8273 		new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
8274 		break;
8275 	case ALGORITHM_RIGHT_ASYMMETRIC:
8276 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
8277 		break;
8278 	case ALGORITHM_LEFT_SYMMETRIC:
8279 		new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
8280 		break;
8281 	case ALGORITHM_RIGHT_SYMMETRIC:
8282 		new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
8283 		break;
8284 	case ALGORITHM_PARITY_0:
8285 		new_layout = ALGORITHM_PARITY_0_6;
8286 		break;
8287 	case ALGORITHM_PARITY_N:
8288 		new_layout = ALGORITHM_PARITY_N;
8289 		break;
8290 	default:
8291 		return ERR_PTR(-EINVAL);
8292 	}
8293 	mddev->new_level = 6;
8294 	mddev->new_layout = new_layout;
8295 	mddev->delta_disks = 1;
8296 	mddev->raid_disks += 1;
8297 	return setup_conf(mddev);
8298 }
8299 
8300 static int raid5_change_consistency_policy(struct mddev *mddev, const char *buf)
8301 {
8302 	struct r5conf *conf;
8303 	int err;
8304 
8305 	err = mddev_lock(mddev);
8306 	if (err)
8307 		return err;
8308 	conf = mddev->private;
8309 	if (!conf) {
8310 		mddev_unlock(mddev);
8311 		return -ENODEV;
8312 	}
8313 
8314 	if (strncmp(buf, "ppl", 3) == 0) {
8315 		/* ppl only works with RAID 5 */
8316 		if (!raid5_has_ppl(conf) && conf->level == 5) {
8317 			err = log_init(conf, NULL, true);
8318 			if (!err) {
8319 				err = resize_stripes(conf, conf->pool_size);
8320 				if (err)
8321 					log_exit(conf);
8322 			}
8323 		} else
8324 			err = -EINVAL;
8325 	} else if (strncmp(buf, "resync", 6) == 0) {
8326 		if (raid5_has_ppl(conf)) {
8327 			mddev_suspend(mddev);
8328 			log_exit(conf);
8329 			mddev_resume(mddev);
8330 			err = resize_stripes(conf, conf->pool_size);
8331 		} else if (test_bit(MD_HAS_JOURNAL, &conf->mddev->flags) &&
8332 			   r5l_log_disk_error(conf)) {
8333 			bool journal_dev_exists = false;
8334 			struct md_rdev *rdev;
8335 
8336 			rdev_for_each(rdev, mddev)
8337 				if (test_bit(Journal, &rdev->flags)) {
8338 					journal_dev_exists = true;
8339 					break;
8340 				}
8341 
8342 			if (!journal_dev_exists) {
8343 				mddev_suspend(mddev);
8344 				clear_bit(MD_HAS_JOURNAL, &mddev->flags);
8345 				mddev_resume(mddev);
8346 			} else  /* need remove journal device first */
8347 				err = -EBUSY;
8348 		} else
8349 			err = -EINVAL;
8350 	} else {
8351 		err = -EINVAL;
8352 	}
8353 
8354 	if (!err)
8355 		md_update_sb(mddev, 1);
8356 
8357 	mddev_unlock(mddev);
8358 
8359 	return err;
8360 }
8361 
8362 static struct md_personality raid6_personality =
8363 {
8364 	.name		= "raid6",
8365 	.level		= 6,
8366 	.owner		= THIS_MODULE,
8367 	.make_request	= raid5_make_request,
8368 	.run		= raid5_run,
8369 	.free		= raid5_free,
8370 	.status		= raid5_status,
8371 	.error_handler	= raid5_error,
8372 	.hot_add_disk	= raid5_add_disk,
8373 	.hot_remove_disk= raid5_remove_disk,
8374 	.spare_active	= raid5_spare_active,
8375 	.sync_request	= raid5_sync_request,
8376 	.resize		= raid5_resize,
8377 	.size		= raid5_size,
8378 	.check_reshape	= raid6_check_reshape,
8379 	.start_reshape  = raid5_start_reshape,
8380 	.finish_reshape = raid5_finish_reshape,
8381 	.quiesce	= raid5_quiesce,
8382 	.takeover	= raid6_takeover,
8383 	.congested	= raid5_congested,
8384 	.change_consistency_policy = raid5_change_consistency_policy,
8385 };
8386 static struct md_personality raid5_personality =
8387 {
8388 	.name		= "raid5",
8389 	.level		= 5,
8390 	.owner		= THIS_MODULE,
8391 	.make_request	= raid5_make_request,
8392 	.run		= raid5_run,
8393 	.free		= raid5_free,
8394 	.status		= raid5_status,
8395 	.error_handler	= raid5_error,
8396 	.hot_add_disk	= raid5_add_disk,
8397 	.hot_remove_disk= raid5_remove_disk,
8398 	.spare_active	= raid5_spare_active,
8399 	.sync_request	= raid5_sync_request,
8400 	.resize		= raid5_resize,
8401 	.size		= raid5_size,
8402 	.check_reshape	= raid5_check_reshape,
8403 	.start_reshape  = raid5_start_reshape,
8404 	.finish_reshape = raid5_finish_reshape,
8405 	.quiesce	= raid5_quiesce,
8406 	.takeover	= raid5_takeover,
8407 	.congested	= raid5_congested,
8408 	.change_consistency_policy = raid5_change_consistency_policy,
8409 };
8410 
8411 static struct md_personality raid4_personality =
8412 {
8413 	.name		= "raid4",
8414 	.level		= 4,
8415 	.owner		= THIS_MODULE,
8416 	.make_request	= raid5_make_request,
8417 	.run		= raid5_run,
8418 	.free		= raid5_free,
8419 	.status		= raid5_status,
8420 	.error_handler	= raid5_error,
8421 	.hot_add_disk	= raid5_add_disk,
8422 	.hot_remove_disk= raid5_remove_disk,
8423 	.spare_active	= raid5_spare_active,
8424 	.sync_request	= raid5_sync_request,
8425 	.resize		= raid5_resize,
8426 	.size		= raid5_size,
8427 	.check_reshape	= raid5_check_reshape,
8428 	.start_reshape  = raid5_start_reshape,
8429 	.finish_reshape = raid5_finish_reshape,
8430 	.quiesce	= raid5_quiesce,
8431 	.takeover	= raid4_takeover,
8432 	.congested	= raid5_congested,
8433 	.change_consistency_policy = raid5_change_consistency_policy,
8434 };
8435 
8436 static int __init raid5_init(void)
8437 {
8438 	int ret;
8439 
8440 	raid5_wq = alloc_workqueue("raid5wq",
8441 		WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
8442 	if (!raid5_wq)
8443 		return -ENOMEM;
8444 
8445 	ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
8446 				      "md/raid5:prepare",
8447 				      raid456_cpu_up_prepare,
8448 				      raid456_cpu_dead);
8449 	if (ret) {
8450 		destroy_workqueue(raid5_wq);
8451 		return ret;
8452 	}
8453 	register_md_personality(&raid6_personality);
8454 	register_md_personality(&raid5_personality);
8455 	register_md_personality(&raid4_personality);
8456 	return 0;
8457 }
8458 
8459 static void raid5_exit(void)
8460 {
8461 	unregister_md_personality(&raid6_personality);
8462 	unregister_md_personality(&raid5_personality);
8463 	unregister_md_personality(&raid4_personality);
8464 	cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
8465 	destroy_workqueue(raid5_wq);
8466 }
8467 
8468 module_init(raid5_init);
8469 module_exit(raid5_exit);
8470 MODULE_LICENSE("GPL");
8471 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
8472 MODULE_ALIAS("md-personality-4"); /* RAID5 */
8473 MODULE_ALIAS("md-raid5");
8474 MODULE_ALIAS("md-raid4");
8475 MODULE_ALIAS("md-level-5");
8476 MODULE_ALIAS("md-level-4");
8477 MODULE_ALIAS("md-personality-8"); /* RAID6 */
8478 MODULE_ALIAS("md-raid6");
8479 MODULE_ALIAS("md-level-6");
8480 
8481 /* This used to be two separate modules, they were: */
8482 MODULE_ALIAS("raid5");
8483 MODULE_ALIAS("raid6");
8484