xref: /openbmc/linux/drivers/md/raid5.c (revision e2f1cf25)
1 /*
2  * raid5.c : Multiple Devices driver for Linux
3  *	   Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
4  *	   Copyright (C) 1999, 2000 Ingo Molnar
5  *	   Copyright (C) 2002, 2003 H. Peter Anvin
6  *
7  * RAID-4/5/6 management functions.
8  * Thanks to Penguin Computing for making the RAID-6 development possible
9  * by donating a test server!
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2, or (at your option)
14  * any later version.
15  *
16  * You should have received a copy of the GNU General Public License
17  * (for example /usr/src/linux/COPYING); if not, write to the Free
18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 /*
22  * BITMAP UNPLUGGING:
23  *
24  * The sequencing for updating the bitmap reliably is a little
25  * subtle (and I got it wrong the first time) so it deserves some
26  * explanation.
27  *
28  * We group bitmap updates into batches.  Each batch has a number.
29  * We may write out several batches at once, but that isn't very important.
30  * conf->seq_write is the number of the last batch successfully written.
31  * conf->seq_flush is the number of the last batch that was closed to
32  *    new additions.
33  * When we discover that we will need to write to any block in a stripe
34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
35  * the number of the batch it will be in. This is seq_flush+1.
36  * When we are ready to do a write, if that batch hasn't been written yet,
37  *   we plug the array and queue the stripe for later.
38  * When an unplug happens, we increment bm_flush, thus closing the current
39  *   batch.
40  * When we notice that bm_flush > bm_write, we write out all pending updates
41  * to the bitmap, and advance bm_write to where bm_flush was.
42  * This may occasionally write a bit out twice, but is sure never to
43  * miss any bits.
44  */
45 
46 #include <linux/blkdev.h>
47 #include <linux/kthread.h>
48 #include <linux/raid/pq.h>
49 #include <linux/async_tx.h>
50 #include <linux/module.h>
51 #include <linux/async.h>
52 #include <linux/seq_file.h>
53 #include <linux/cpu.h>
54 #include <linux/slab.h>
55 #include <linux/ratelimit.h>
56 #include <linux/nodemask.h>
57 #include <linux/flex_array.h>
58 #include <trace/events/block.h>
59 
60 #include "md.h"
61 #include "raid5.h"
62 #include "raid0.h"
63 #include "bitmap.h"
64 
65 #define cpu_to_group(cpu) cpu_to_node(cpu)
66 #define ANY_GROUP NUMA_NO_NODE
67 
68 static bool devices_handle_discard_safely = false;
69 module_param(devices_handle_discard_safely, bool, 0644);
70 MODULE_PARM_DESC(devices_handle_discard_safely,
71 		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
72 static struct workqueue_struct *raid5_wq;
73 /*
74  * Stripe cache
75  */
76 
77 #define NR_STRIPES		256
78 #define STRIPE_SIZE		PAGE_SIZE
79 #define STRIPE_SHIFT		(PAGE_SHIFT - 9)
80 #define STRIPE_SECTORS		(STRIPE_SIZE>>9)
81 #define	IO_THRESHOLD		1
82 #define BYPASS_THRESHOLD	1
83 #define NR_HASH			(PAGE_SIZE / sizeof(struct hlist_head))
84 #define HASH_MASK		(NR_HASH - 1)
85 #define MAX_STRIPE_BATCH	8
86 
87 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
88 {
89 	int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
90 	return &conf->stripe_hashtbl[hash];
91 }
92 
93 static inline int stripe_hash_locks_hash(sector_t sect)
94 {
95 	return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
96 }
97 
98 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
99 {
100 	spin_lock_irq(conf->hash_locks + hash);
101 	spin_lock(&conf->device_lock);
102 }
103 
104 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
105 {
106 	spin_unlock(&conf->device_lock);
107 	spin_unlock_irq(conf->hash_locks + hash);
108 }
109 
110 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
111 {
112 	int i;
113 	local_irq_disable();
114 	spin_lock(conf->hash_locks);
115 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
116 		spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
117 	spin_lock(&conf->device_lock);
118 }
119 
120 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
121 {
122 	int i;
123 	spin_unlock(&conf->device_lock);
124 	for (i = NR_STRIPE_HASH_LOCKS; i; i--)
125 		spin_unlock(conf->hash_locks + i - 1);
126 	local_irq_enable();
127 }
128 
129 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
130  * order without overlap.  There may be several bio's per stripe+device, and
131  * a bio could span several devices.
132  * When walking this list for a particular stripe+device, we must never proceed
133  * beyond a bio that extends past this device, as the next bio might no longer
134  * be valid.
135  * This function is used to determine the 'next' bio in the list, given the sector
136  * of the current stripe+device
137  */
138 static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
139 {
140 	int sectors = bio_sectors(bio);
141 	if (bio->bi_iter.bi_sector + sectors < sector + STRIPE_SECTORS)
142 		return bio->bi_next;
143 	else
144 		return NULL;
145 }
146 
147 /*
148  * We maintain a biased count of active stripes in the bottom 16 bits of
149  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
150  */
151 static inline int raid5_bi_processed_stripes(struct bio *bio)
152 {
153 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
154 	return (atomic_read(segments) >> 16) & 0xffff;
155 }
156 
157 static inline int raid5_dec_bi_active_stripes(struct bio *bio)
158 {
159 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
160 	return atomic_sub_return(1, segments) & 0xffff;
161 }
162 
163 static inline void raid5_inc_bi_active_stripes(struct bio *bio)
164 {
165 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
166 	atomic_inc(segments);
167 }
168 
169 static inline void raid5_set_bi_processed_stripes(struct bio *bio,
170 	unsigned int cnt)
171 {
172 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
173 	int old, new;
174 
175 	do {
176 		old = atomic_read(segments);
177 		new = (old & 0xffff) | (cnt << 16);
178 	} while (atomic_cmpxchg(segments, old, new) != old);
179 }
180 
181 static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
182 {
183 	atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
184 	atomic_set(segments, cnt);
185 }
186 
187 /* Find first data disk in a raid6 stripe */
188 static inline int raid6_d0(struct stripe_head *sh)
189 {
190 	if (sh->ddf_layout)
191 		/* ddf always start from first device */
192 		return 0;
193 	/* md starts just after Q block */
194 	if (sh->qd_idx == sh->disks - 1)
195 		return 0;
196 	else
197 		return sh->qd_idx + 1;
198 }
199 static inline int raid6_next_disk(int disk, int raid_disks)
200 {
201 	disk++;
202 	return (disk < raid_disks) ? disk : 0;
203 }
204 
205 /* When walking through the disks in a raid5, starting at raid6_d0,
206  * We need to map each disk to a 'slot', where the data disks are slot
207  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
208  * is raid_disks-1.  This help does that mapping.
209  */
210 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
211 			     int *count, int syndrome_disks)
212 {
213 	int slot = *count;
214 
215 	if (sh->ddf_layout)
216 		(*count)++;
217 	if (idx == sh->pd_idx)
218 		return syndrome_disks;
219 	if (idx == sh->qd_idx)
220 		return syndrome_disks + 1;
221 	if (!sh->ddf_layout)
222 		(*count)++;
223 	return slot;
224 }
225 
226 static void return_io(struct bio *return_bi)
227 {
228 	struct bio *bi = return_bi;
229 	while (bi) {
230 
231 		return_bi = bi->bi_next;
232 		bi->bi_next = NULL;
233 		bi->bi_iter.bi_size = 0;
234 		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
235 					 bi, 0);
236 		bio_endio(bi, 0);
237 		bi = return_bi;
238 	}
239 }
240 
241 static void print_raid5_conf (struct r5conf *conf);
242 
243 static int stripe_operations_active(struct stripe_head *sh)
244 {
245 	return sh->check_state || sh->reconstruct_state ||
246 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
247 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
248 }
249 
250 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
251 {
252 	struct r5conf *conf = sh->raid_conf;
253 	struct r5worker_group *group;
254 	int thread_cnt;
255 	int i, cpu = sh->cpu;
256 
257 	if (!cpu_online(cpu)) {
258 		cpu = cpumask_any(cpu_online_mask);
259 		sh->cpu = cpu;
260 	}
261 
262 	if (list_empty(&sh->lru)) {
263 		struct r5worker_group *group;
264 		group = conf->worker_groups + cpu_to_group(cpu);
265 		list_add_tail(&sh->lru, &group->handle_list);
266 		group->stripes_cnt++;
267 		sh->group = group;
268 	}
269 
270 	if (conf->worker_cnt_per_group == 0) {
271 		md_wakeup_thread(conf->mddev->thread);
272 		return;
273 	}
274 
275 	group = conf->worker_groups + cpu_to_group(sh->cpu);
276 
277 	group->workers[0].working = true;
278 	/* at least one worker should run to avoid race */
279 	queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
280 
281 	thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
282 	/* wakeup more workers */
283 	for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
284 		if (group->workers[i].working == false) {
285 			group->workers[i].working = true;
286 			queue_work_on(sh->cpu, raid5_wq,
287 				      &group->workers[i].work);
288 			thread_cnt--;
289 		}
290 	}
291 }
292 
293 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
294 			      struct list_head *temp_inactive_list)
295 {
296 	BUG_ON(!list_empty(&sh->lru));
297 	BUG_ON(atomic_read(&conf->active_stripes)==0);
298 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
299 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
300 		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
301 			list_add_tail(&sh->lru, &conf->delayed_list);
302 		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
303 			   sh->bm_seq - conf->seq_write > 0)
304 			list_add_tail(&sh->lru, &conf->bitmap_list);
305 		else {
306 			clear_bit(STRIPE_DELAYED, &sh->state);
307 			clear_bit(STRIPE_BIT_DELAY, &sh->state);
308 			if (conf->worker_cnt_per_group == 0) {
309 				list_add_tail(&sh->lru, &conf->handle_list);
310 			} else {
311 				raid5_wakeup_stripe_thread(sh);
312 				return;
313 			}
314 		}
315 		md_wakeup_thread(conf->mddev->thread);
316 	} else {
317 		BUG_ON(stripe_operations_active(sh));
318 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
319 			if (atomic_dec_return(&conf->preread_active_stripes)
320 			    < IO_THRESHOLD)
321 				md_wakeup_thread(conf->mddev->thread);
322 		atomic_dec(&conf->active_stripes);
323 		if (!test_bit(STRIPE_EXPANDING, &sh->state))
324 			list_add_tail(&sh->lru, temp_inactive_list);
325 	}
326 }
327 
328 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
329 			     struct list_head *temp_inactive_list)
330 {
331 	if (atomic_dec_and_test(&sh->count))
332 		do_release_stripe(conf, sh, temp_inactive_list);
333 }
334 
335 /*
336  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
337  *
338  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
339  * given time. Adding stripes only takes device lock, while deleting stripes
340  * only takes hash lock.
341  */
342 static void release_inactive_stripe_list(struct r5conf *conf,
343 					 struct list_head *temp_inactive_list,
344 					 int hash)
345 {
346 	int size;
347 	unsigned long do_wakeup = 0;
348 	int i = 0;
349 	unsigned long flags;
350 
351 	if (hash == NR_STRIPE_HASH_LOCKS) {
352 		size = NR_STRIPE_HASH_LOCKS;
353 		hash = NR_STRIPE_HASH_LOCKS - 1;
354 	} else
355 		size = 1;
356 	while (size) {
357 		struct list_head *list = &temp_inactive_list[size - 1];
358 
359 		/*
360 		 * We don't hold any lock here yet, get_active_stripe() might
361 		 * remove stripes from the list
362 		 */
363 		if (!list_empty_careful(list)) {
364 			spin_lock_irqsave(conf->hash_locks + hash, flags);
365 			if (list_empty(conf->inactive_list + hash) &&
366 			    !list_empty(list))
367 				atomic_dec(&conf->empty_inactive_list_nr);
368 			list_splice_tail_init(list, conf->inactive_list + hash);
369 			do_wakeup |= 1 << hash;
370 			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
371 		}
372 		size--;
373 		hash--;
374 	}
375 
376 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++) {
377 		if (do_wakeup & (1 << i))
378 			wake_up(&conf->wait_for_stripe[i]);
379 	}
380 
381 	if (do_wakeup) {
382 		if (atomic_read(&conf->active_stripes) == 0)
383 			wake_up(&conf->wait_for_quiescent);
384 		if (conf->retry_read_aligned)
385 			md_wakeup_thread(conf->mddev->thread);
386 	}
387 }
388 
389 /* should hold conf->device_lock already */
390 static int release_stripe_list(struct r5conf *conf,
391 			       struct list_head *temp_inactive_list)
392 {
393 	struct stripe_head *sh;
394 	int count = 0;
395 	struct llist_node *head;
396 
397 	head = llist_del_all(&conf->released_stripes);
398 	head = llist_reverse_order(head);
399 	while (head) {
400 		int hash;
401 
402 		sh = llist_entry(head, struct stripe_head, release_list);
403 		head = llist_next(head);
404 		/* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
405 		smp_mb();
406 		clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
407 		/*
408 		 * Don't worry the bit is set here, because if the bit is set
409 		 * again, the count is always > 1. This is true for
410 		 * STRIPE_ON_UNPLUG_LIST bit too.
411 		 */
412 		hash = sh->hash_lock_index;
413 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
414 		count++;
415 	}
416 
417 	return count;
418 }
419 
420 static void release_stripe(struct stripe_head *sh)
421 {
422 	struct r5conf *conf = sh->raid_conf;
423 	unsigned long flags;
424 	struct list_head list;
425 	int hash;
426 	bool wakeup;
427 
428 	/* Avoid release_list until the last reference.
429 	 */
430 	if (atomic_add_unless(&sh->count, -1, 1))
431 		return;
432 
433 	if (unlikely(!conf->mddev->thread) ||
434 		test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
435 		goto slow_path;
436 	wakeup = llist_add(&sh->release_list, &conf->released_stripes);
437 	if (wakeup)
438 		md_wakeup_thread(conf->mddev->thread);
439 	return;
440 slow_path:
441 	local_irq_save(flags);
442 	/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
443 	if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
444 		INIT_LIST_HEAD(&list);
445 		hash = sh->hash_lock_index;
446 		do_release_stripe(conf, sh, &list);
447 		spin_unlock(&conf->device_lock);
448 		release_inactive_stripe_list(conf, &list, hash);
449 	}
450 	local_irq_restore(flags);
451 }
452 
453 static inline void remove_hash(struct stripe_head *sh)
454 {
455 	pr_debug("remove_hash(), stripe %llu\n",
456 		(unsigned long long)sh->sector);
457 
458 	hlist_del_init(&sh->hash);
459 }
460 
461 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
462 {
463 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
464 
465 	pr_debug("insert_hash(), stripe %llu\n",
466 		(unsigned long long)sh->sector);
467 
468 	hlist_add_head(&sh->hash, hp);
469 }
470 
471 /* find an idle stripe, make sure it is unhashed, and return it. */
472 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
473 {
474 	struct stripe_head *sh = NULL;
475 	struct list_head *first;
476 
477 	if (list_empty(conf->inactive_list + hash))
478 		goto out;
479 	first = (conf->inactive_list + hash)->next;
480 	sh = list_entry(first, struct stripe_head, lru);
481 	list_del_init(first);
482 	remove_hash(sh);
483 	atomic_inc(&conf->active_stripes);
484 	BUG_ON(hash != sh->hash_lock_index);
485 	if (list_empty(conf->inactive_list + hash))
486 		atomic_inc(&conf->empty_inactive_list_nr);
487 out:
488 	return sh;
489 }
490 
491 static void shrink_buffers(struct stripe_head *sh)
492 {
493 	struct page *p;
494 	int i;
495 	int num = sh->raid_conf->pool_size;
496 
497 	for (i = 0; i < num ; i++) {
498 		WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
499 		p = sh->dev[i].page;
500 		if (!p)
501 			continue;
502 		sh->dev[i].page = NULL;
503 		put_page(p);
504 	}
505 }
506 
507 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
508 {
509 	int i;
510 	int num = sh->raid_conf->pool_size;
511 
512 	for (i = 0; i < num; i++) {
513 		struct page *page;
514 
515 		if (!(page = alloc_page(gfp))) {
516 			return 1;
517 		}
518 		sh->dev[i].page = page;
519 		sh->dev[i].orig_page = page;
520 	}
521 	return 0;
522 }
523 
524 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
525 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
526 			    struct stripe_head *sh);
527 
528 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
529 {
530 	struct r5conf *conf = sh->raid_conf;
531 	int i, seq;
532 
533 	BUG_ON(atomic_read(&sh->count) != 0);
534 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
535 	BUG_ON(stripe_operations_active(sh));
536 	BUG_ON(sh->batch_head);
537 
538 	pr_debug("init_stripe called, stripe %llu\n",
539 		(unsigned long long)sector);
540 retry:
541 	seq = read_seqcount_begin(&conf->gen_lock);
542 	sh->generation = conf->generation - previous;
543 	sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
544 	sh->sector = sector;
545 	stripe_set_idx(sector, conf, previous, sh);
546 	sh->state = 0;
547 
548 	for (i = sh->disks; i--; ) {
549 		struct r5dev *dev = &sh->dev[i];
550 
551 		if (dev->toread || dev->read || dev->towrite || dev->written ||
552 		    test_bit(R5_LOCKED, &dev->flags)) {
553 			printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
554 			       (unsigned long long)sh->sector, i, dev->toread,
555 			       dev->read, dev->towrite, dev->written,
556 			       test_bit(R5_LOCKED, &dev->flags));
557 			WARN_ON(1);
558 		}
559 		dev->flags = 0;
560 		raid5_build_block(sh, i, previous);
561 	}
562 	if (read_seqcount_retry(&conf->gen_lock, seq))
563 		goto retry;
564 	sh->overwrite_disks = 0;
565 	insert_hash(conf, sh);
566 	sh->cpu = smp_processor_id();
567 	set_bit(STRIPE_BATCH_READY, &sh->state);
568 }
569 
570 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
571 					 short generation)
572 {
573 	struct stripe_head *sh;
574 
575 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
576 	hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
577 		if (sh->sector == sector && sh->generation == generation)
578 			return sh;
579 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
580 	return NULL;
581 }
582 
583 /*
584  * Need to check if array has failed when deciding whether to:
585  *  - start an array
586  *  - remove non-faulty devices
587  *  - add a spare
588  *  - allow a reshape
589  * This determination is simple when no reshape is happening.
590  * However if there is a reshape, we need to carefully check
591  * both the before and after sections.
592  * This is because some failed devices may only affect one
593  * of the two sections, and some non-in_sync devices may
594  * be insync in the section most affected by failed devices.
595  */
596 static int calc_degraded(struct r5conf *conf)
597 {
598 	int degraded, degraded2;
599 	int i;
600 
601 	rcu_read_lock();
602 	degraded = 0;
603 	for (i = 0; i < conf->previous_raid_disks; i++) {
604 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
605 		if (rdev && test_bit(Faulty, &rdev->flags))
606 			rdev = rcu_dereference(conf->disks[i].replacement);
607 		if (!rdev || test_bit(Faulty, &rdev->flags))
608 			degraded++;
609 		else if (test_bit(In_sync, &rdev->flags))
610 			;
611 		else
612 			/* not in-sync or faulty.
613 			 * If the reshape increases the number of devices,
614 			 * this is being recovered by the reshape, so
615 			 * this 'previous' section is not in_sync.
616 			 * If the number of devices is being reduced however,
617 			 * the device can only be part of the array if
618 			 * we are reverting a reshape, so this section will
619 			 * be in-sync.
620 			 */
621 			if (conf->raid_disks >= conf->previous_raid_disks)
622 				degraded++;
623 	}
624 	rcu_read_unlock();
625 	if (conf->raid_disks == conf->previous_raid_disks)
626 		return degraded;
627 	rcu_read_lock();
628 	degraded2 = 0;
629 	for (i = 0; i < conf->raid_disks; i++) {
630 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
631 		if (rdev && test_bit(Faulty, &rdev->flags))
632 			rdev = rcu_dereference(conf->disks[i].replacement);
633 		if (!rdev || test_bit(Faulty, &rdev->flags))
634 			degraded2++;
635 		else if (test_bit(In_sync, &rdev->flags))
636 			;
637 		else
638 			/* not in-sync or faulty.
639 			 * If reshape increases the number of devices, this
640 			 * section has already been recovered, else it
641 			 * almost certainly hasn't.
642 			 */
643 			if (conf->raid_disks <= conf->previous_raid_disks)
644 				degraded2++;
645 	}
646 	rcu_read_unlock();
647 	if (degraded2 > degraded)
648 		return degraded2;
649 	return degraded;
650 }
651 
652 static int has_failed(struct r5conf *conf)
653 {
654 	int degraded;
655 
656 	if (conf->mddev->reshape_position == MaxSector)
657 		return conf->mddev->degraded > conf->max_degraded;
658 
659 	degraded = calc_degraded(conf);
660 	if (degraded > conf->max_degraded)
661 		return 1;
662 	return 0;
663 }
664 
665 static struct stripe_head *
666 get_active_stripe(struct r5conf *conf, sector_t sector,
667 		  int previous, int noblock, int noquiesce)
668 {
669 	struct stripe_head *sh;
670 	int hash = stripe_hash_locks_hash(sector);
671 
672 	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
673 
674 	spin_lock_irq(conf->hash_locks + hash);
675 
676 	do {
677 		wait_event_lock_irq(conf->wait_for_quiescent,
678 				    conf->quiesce == 0 || noquiesce,
679 				    *(conf->hash_locks + hash));
680 		sh = __find_stripe(conf, sector, conf->generation - previous);
681 		if (!sh) {
682 			if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
683 				sh = get_free_stripe(conf, hash);
684 				if (!sh && !test_bit(R5_DID_ALLOC,
685 						     &conf->cache_state))
686 					set_bit(R5_ALLOC_MORE,
687 						&conf->cache_state);
688 			}
689 			if (noblock && sh == NULL)
690 				break;
691 			if (!sh) {
692 				set_bit(R5_INACTIVE_BLOCKED,
693 					&conf->cache_state);
694 				wait_event_exclusive_cmd(
695 					conf->wait_for_stripe[hash],
696 					!list_empty(conf->inactive_list + hash) &&
697 					(atomic_read(&conf->active_stripes)
698 					 < (conf->max_nr_stripes * 3 / 4)
699 					 || !test_bit(R5_INACTIVE_BLOCKED,
700 						      &conf->cache_state)),
701 					spin_unlock_irq(conf->hash_locks + hash),
702 					spin_lock_irq(conf->hash_locks + hash));
703 				clear_bit(R5_INACTIVE_BLOCKED,
704 					  &conf->cache_state);
705 			} else {
706 				init_stripe(sh, sector, previous);
707 				atomic_inc(&sh->count);
708 			}
709 		} else if (!atomic_inc_not_zero(&sh->count)) {
710 			spin_lock(&conf->device_lock);
711 			if (!atomic_read(&sh->count)) {
712 				if (!test_bit(STRIPE_HANDLE, &sh->state))
713 					atomic_inc(&conf->active_stripes);
714 				BUG_ON(list_empty(&sh->lru) &&
715 				       !test_bit(STRIPE_EXPANDING, &sh->state));
716 				list_del_init(&sh->lru);
717 				if (sh->group) {
718 					sh->group->stripes_cnt--;
719 					sh->group = NULL;
720 				}
721 			}
722 			atomic_inc(&sh->count);
723 			spin_unlock(&conf->device_lock);
724 		}
725 	} while (sh == NULL);
726 
727 	if (!list_empty(conf->inactive_list + hash))
728 		wake_up(&conf->wait_for_stripe[hash]);
729 
730 	spin_unlock_irq(conf->hash_locks + hash);
731 	return sh;
732 }
733 
734 static bool is_full_stripe_write(struct stripe_head *sh)
735 {
736 	BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
737 	return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
738 }
739 
740 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
741 {
742 	local_irq_disable();
743 	if (sh1 > sh2) {
744 		spin_lock(&sh2->stripe_lock);
745 		spin_lock_nested(&sh1->stripe_lock, 1);
746 	} else {
747 		spin_lock(&sh1->stripe_lock);
748 		spin_lock_nested(&sh2->stripe_lock, 1);
749 	}
750 }
751 
752 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
753 {
754 	spin_unlock(&sh1->stripe_lock);
755 	spin_unlock(&sh2->stripe_lock);
756 	local_irq_enable();
757 }
758 
759 /* Only freshly new full stripe normal write stripe can be added to a batch list */
760 static bool stripe_can_batch(struct stripe_head *sh)
761 {
762 	return test_bit(STRIPE_BATCH_READY, &sh->state) &&
763 		!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
764 		is_full_stripe_write(sh);
765 }
766 
767 /* we only do back search */
768 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
769 {
770 	struct stripe_head *head;
771 	sector_t head_sector, tmp_sec;
772 	int hash;
773 	int dd_idx;
774 
775 	if (!stripe_can_batch(sh))
776 		return;
777 	/* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
778 	tmp_sec = sh->sector;
779 	if (!sector_div(tmp_sec, conf->chunk_sectors))
780 		return;
781 	head_sector = sh->sector - STRIPE_SECTORS;
782 
783 	hash = stripe_hash_locks_hash(head_sector);
784 	spin_lock_irq(conf->hash_locks + hash);
785 	head = __find_stripe(conf, head_sector, conf->generation);
786 	if (head && !atomic_inc_not_zero(&head->count)) {
787 		spin_lock(&conf->device_lock);
788 		if (!atomic_read(&head->count)) {
789 			if (!test_bit(STRIPE_HANDLE, &head->state))
790 				atomic_inc(&conf->active_stripes);
791 			BUG_ON(list_empty(&head->lru) &&
792 			       !test_bit(STRIPE_EXPANDING, &head->state));
793 			list_del_init(&head->lru);
794 			if (head->group) {
795 				head->group->stripes_cnt--;
796 				head->group = NULL;
797 			}
798 		}
799 		atomic_inc(&head->count);
800 		spin_unlock(&conf->device_lock);
801 	}
802 	spin_unlock_irq(conf->hash_locks + hash);
803 
804 	if (!head)
805 		return;
806 	if (!stripe_can_batch(head))
807 		goto out;
808 
809 	lock_two_stripes(head, sh);
810 	/* clear_batch_ready clear the flag */
811 	if (!stripe_can_batch(head) || !stripe_can_batch(sh))
812 		goto unlock_out;
813 
814 	if (sh->batch_head)
815 		goto unlock_out;
816 
817 	dd_idx = 0;
818 	while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
819 		dd_idx++;
820 	if (head->dev[dd_idx].towrite->bi_rw != sh->dev[dd_idx].towrite->bi_rw)
821 		goto unlock_out;
822 
823 	if (head->batch_head) {
824 		spin_lock(&head->batch_head->batch_lock);
825 		/* This batch list is already running */
826 		if (!stripe_can_batch(head)) {
827 			spin_unlock(&head->batch_head->batch_lock);
828 			goto unlock_out;
829 		}
830 
831 		/*
832 		 * at this point, head's BATCH_READY could be cleared, but we
833 		 * can still add the stripe to batch list
834 		 */
835 		list_add(&sh->batch_list, &head->batch_list);
836 		spin_unlock(&head->batch_head->batch_lock);
837 
838 		sh->batch_head = head->batch_head;
839 	} else {
840 		head->batch_head = head;
841 		sh->batch_head = head->batch_head;
842 		spin_lock(&head->batch_lock);
843 		list_add_tail(&sh->batch_list, &head->batch_list);
844 		spin_unlock(&head->batch_lock);
845 	}
846 
847 	if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
848 		if (atomic_dec_return(&conf->preread_active_stripes)
849 		    < IO_THRESHOLD)
850 			md_wakeup_thread(conf->mddev->thread);
851 
852 	if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
853 		int seq = sh->bm_seq;
854 		if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
855 		    sh->batch_head->bm_seq > seq)
856 			seq = sh->batch_head->bm_seq;
857 		set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
858 		sh->batch_head->bm_seq = seq;
859 	}
860 
861 	atomic_inc(&sh->count);
862 unlock_out:
863 	unlock_two_stripes(head, sh);
864 out:
865 	release_stripe(head);
866 }
867 
868 /* Determine if 'data_offset' or 'new_data_offset' should be used
869  * in this stripe_head.
870  */
871 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
872 {
873 	sector_t progress = conf->reshape_progress;
874 	/* Need a memory barrier to make sure we see the value
875 	 * of conf->generation, or ->data_offset that was set before
876 	 * reshape_progress was updated.
877 	 */
878 	smp_rmb();
879 	if (progress == MaxSector)
880 		return 0;
881 	if (sh->generation == conf->generation - 1)
882 		return 0;
883 	/* We are in a reshape, and this is a new-generation stripe,
884 	 * so use new_data_offset.
885 	 */
886 	return 1;
887 }
888 
889 static void
890 raid5_end_read_request(struct bio *bi, int error);
891 static void
892 raid5_end_write_request(struct bio *bi, int error);
893 
894 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
895 {
896 	struct r5conf *conf = sh->raid_conf;
897 	int i, disks = sh->disks;
898 	struct stripe_head *head_sh = sh;
899 
900 	might_sleep();
901 
902 	for (i = disks; i--; ) {
903 		int rw;
904 		int replace_only = 0;
905 		struct bio *bi, *rbi;
906 		struct md_rdev *rdev, *rrdev = NULL;
907 
908 		sh = head_sh;
909 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
910 			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
911 				rw = WRITE_FUA;
912 			else
913 				rw = WRITE;
914 			if (test_bit(R5_Discard, &sh->dev[i].flags))
915 				rw |= REQ_DISCARD;
916 		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
917 			rw = READ;
918 		else if (test_and_clear_bit(R5_WantReplace,
919 					    &sh->dev[i].flags)) {
920 			rw = WRITE;
921 			replace_only = 1;
922 		} else
923 			continue;
924 		if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
925 			rw |= REQ_SYNC;
926 
927 again:
928 		bi = &sh->dev[i].req;
929 		rbi = &sh->dev[i].rreq; /* For writing to replacement */
930 
931 		rcu_read_lock();
932 		rrdev = rcu_dereference(conf->disks[i].replacement);
933 		smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
934 		rdev = rcu_dereference(conf->disks[i].rdev);
935 		if (!rdev) {
936 			rdev = rrdev;
937 			rrdev = NULL;
938 		}
939 		if (rw & WRITE) {
940 			if (replace_only)
941 				rdev = NULL;
942 			if (rdev == rrdev)
943 				/* We raced and saw duplicates */
944 				rrdev = NULL;
945 		} else {
946 			if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
947 				rdev = rrdev;
948 			rrdev = NULL;
949 		}
950 
951 		if (rdev && test_bit(Faulty, &rdev->flags))
952 			rdev = NULL;
953 		if (rdev)
954 			atomic_inc(&rdev->nr_pending);
955 		if (rrdev && test_bit(Faulty, &rrdev->flags))
956 			rrdev = NULL;
957 		if (rrdev)
958 			atomic_inc(&rrdev->nr_pending);
959 		rcu_read_unlock();
960 
961 		/* We have already checked bad blocks for reads.  Now
962 		 * need to check for writes.  We never accept write errors
963 		 * on the replacement, so we don't to check rrdev.
964 		 */
965 		while ((rw & WRITE) && rdev &&
966 		       test_bit(WriteErrorSeen, &rdev->flags)) {
967 			sector_t first_bad;
968 			int bad_sectors;
969 			int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
970 					      &first_bad, &bad_sectors);
971 			if (!bad)
972 				break;
973 
974 			if (bad < 0) {
975 				set_bit(BlockedBadBlocks, &rdev->flags);
976 				if (!conf->mddev->external &&
977 				    conf->mddev->flags) {
978 					/* It is very unlikely, but we might
979 					 * still need to write out the
980 					 * bad block log - better give it
981 					 * a chance*/
982 					md_check_recovery(conf->mddev);
983 				}
984 				/*
985 				 * Because md_wait_for_blocked_rdev
986 				 * will dec nr_pending, we must
987 				 * increment it first.
988 				 */
989 				atomic_inc(&rdev->nr_pending);
990 				md_wait_for_blocked_rdev(rdev, conf->mddev);
991 			} else {
992 				/* Acknowledged bad block - skip the write */
993 				rdev_dec_pending(rdev, conf->mddev);
994 				rdev = NULL;
995 			}
996 		}
997 
998 		if (rdev) {
999 			if (s->syncing || s->expanding || s->expanded
1000 			    || s->replacing)
1001 				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1002 
1003 			set_bit(STRIPE_IO_STARTED, &sh->state);
1004 
1005 			bio_reset(bi);
1006 			bi->bi_bdev = rdev->bdev;
1007 			bi->bi_rw = rw;
1008 			bi->bi_end_io = (rw & WRITE)
1009 				? raid5_end_write_request
1010 				: raid5_end_read_request;
1011 			bi->bi_private = sh;
1012 
1013 			pr_debug("%s: for %llu schedule op %ld on disc %d\n",
1014 				__func__, (unsigned long long)sh->sector,
1015 				bi->bi_rw, i);
1016 			atomic_inc(&sh->count);
1017 			if (sh != head_sh)
1018 				atomic_inc(&head_sh->count);
1019 			if (use_new_offset(conf, sh))
1020 				bi->bi_iter.bi_sector = (sh->sector
1021 						 + rdev->new_data_offset);
1022 			else
1023 				bi->bi_iter.bi_sector = (sh->sector
1024 						 + rdev->data_offset);
1025 			if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1026 				bi->bi_rw |= REQ_NOMERGE;
1027 
1028 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1029 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1030 			sh->dev[i].vec.bv_page = sh->dev[i].page;
1031 			bi->bi_vcnt = 1;
1032 			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1033 			bi->bi_io_vec[0].bv_offset = 0;
1034 			bi->bi_iter.bi_size = STRIPE_SIZE;
1035 			/*
1036 			 * If this is discard request, set bi_vcnt 0. We don't
1037 			 * want to confuse SCSI because SCSI will replace payload
1038 			 */
1039 			if (rw & REQ_DISCARD)
1040 				bi->bi_vcnt = 0;
1041 			if (rrdev)
1042 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1043 
1044 			if (conf->mddev->gendisk)
1045 				trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
1046 						      bi, disk_devt(conf->mddev->gendisk),
1047 						      sh->dev[i].sector);
1048 			generic_make_request(bi);
1049 		}
1050 		if (rrdev) {
1051 			if (s->syncing || s->expanding || s->expanded
1052 			    || s->replacing)
1053 				md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1054 
1055 			set_bit(STRIPE_IO_STARTED, &sh->state);
1056 
1057 			bio_reset(rbi);
1058 			rbi->bi_bdev = rrdev->bdev;
1059 			rbi->bi_rw = rw;
1060 			BUG_ON(!(rw & WRITE));
1061 			rbi->bi_end_io = raid5_end_write_request;
1062 			rbi->bi_private = sh;
1063 
1064 			pr_debug("%s: for %llu schedule op %ld on "
1065 				 "replacement disc %d\n",
1066 				__func__, (unsigned long long)sh->sector,
1067 				rbi->bi_rw, i);
1068 			atomic_inc(&sh->count);
1069 			if (sh != head_sh)
1070 				atomic_inc(&head_sh->count);
1071 			if (use_new_offset(conf, sh))
1072 				rbi->bi_iter.bi_sector = (sh->sector
1073 						  + rrdev->new_data_offset);
1074 			else
1075 				rbi->bi_iter.bi_sector = (sh->sector
1076 						  + rrdev->data_offset);
1077 			if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1078 				WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1079 			sh->dev[i].rvec.bv_page = sh->dev[i].page;
1080 			rbi->bi_vcnt = 1;
1081 			rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1082 			rbi->bi_io_vec[0].bv_offset = 0;
1083 			rbi->bi_iter.bi_size = STRIPE_SIZE;
1084 			/*
1085 			 * If this is discard request, set bi_vcnt 0. We don't
1086 			 * want to confuse SCSI because SCSI will replace payload
1087 			 */
1088 			if (rw & REQ_DISCARD)
1089 				rbi->bi_vcnt = 0;
1090 			if (conf->mddev->gendisk)
1091 				trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
1092 						      rbi, disk_devt(conf->mddev->gendisk),
1093 						      sh->dev[i].sector);
1094 			generic_make_request(rbi);
1095 		}
1096 		if (!rdev && !rrdev) {
1097 			if (rw & WRITE)
1098 				set_bit(STRIPE_DEGRADED, &sh->state);
1099 			pr_debug("skip op %ld on disc %d for sector %llu\n",
1100 				bi->bi_rw, i, (unsigned long long)sh->sector);
1101 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
1102 			set_bit(STRIPE_HANDLE, &sh->state);
1103 		}
1104 
1105 		if (!head_sh->batch_head)
1106 			continue;
1107 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1108 				      batch_list);
1109 		if (sh != head_sh)
1110 			goto again;
1111 	}
1112 }
1113 
1114 static struct dma_async_tx_descriptor *
1115 async_copy_data(int frombio, struct bio *bio, struct page **page,
1116 	sector_t sector, struct dma_async_tx_descriptor *tx,
1117 	struct stripe_head *sh)
1118 {
1119 	struct bio_vec bvl;
1120 	struct bvec_iter iter;
1121 	struct page *bio_page;
1122 	int page_offset;
1123 	struct async_submit_ctl submit;
1124 	enum async_tx_flags flags = 0;
1125 
1126 	if (bio->bi_iter.bi_sector >= sector)
1127 		page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1128 	else
1129 		page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1130 
1131 	if (frombio)
1132 		flags |= ASYNC_TX_FENCE;
1133 	init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1134 
1135 	bio_for_each_segment(bvl, bio, iter) {
1136 		int len = bvl.bv_len;
1137 		int clen;
1138 		int b_offset = 0;
1139 
1140 		if (page_offset < 0) {
1141 			b_offset = -page_offset;
1142 			page_offset += b_offset;
1143 			len -= b_offset;
1144 		}
1145 
1146 		if (len > 0 && page_offset + len > STRIPE_SIZE)
1147 			clen = STRIPE_SIZE - page_offset;
1148 		else
1149 			clen = len;
1150 
1151 		if (clen > 0) {
1152 			b_offset += bvl.bv_offset;
1153 			bio_page = bvl.bv_page;
1154 			if (frombio) {
1155 				if (sh->raid_conf->skip_copy &&
1156 				    b_offset == 0 && page_offset == 0 &&
1157 				    clen == STRIPE_SIZE)
1158 					*page = bio_page;
1159 				else
1160 					tx = async_memcpy(*page, bio_page, page_offset,
1161 						  b_offset, clen, &submit);
1162 			} else
1163 				tx = async_memcpy(bio_page, *page, b_offset,
1164 						  page_offset, clen, &submit);
1165 		}
1166 		/* chain the operations */
1167 		submit.depend_tx = tx;
1168 
1169 		if (clen < len) /* hit end of page */
1170 			break;
1171 		page_offset +=  len;
1172 	}
1173 
1174 	return tx;
1175 }
1176 
1177 static void ops_complete_biofill(void *stripe_head_ref)
1178 {
1179 	struct stripe_head *sh = stripe_head_ref;
1180 	struct bio *return_bi = NULL;
1181 	int i;
1182 
1183 	pr_debug("%s: stripe %llu\n", __func__,
1184 		(unsigned long long)sh->sector);
1185 
1186 	/* clear completed biofills */
1187 	for (i = sh->disks; i--; ) {
1188 		struct r5dev *dev = &sh->dev[i];
1189 
1190 		/* acknowledge completion of a biofill operation */
1191 		/* and check if we need to reply to a read request,
1192 		 * new R5_Wantfill requests are held off until
1193 		 * !STRIPE_BIOFILL_RUN
1194 		 */
1195 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1196 			struct bio *rbi, *rbi2;
1197 
1198 			BUG_ON(!dev->read);
1199 			rbi = dev->read;
1200 			dev->read = NULL;
1201 			while (rbi && rbi->bi_iter.bi_sector <
1202 				dev->sector + STRIPE_SECTORS) {
1203 				rbi2 = r5_next_bio(rbi, dev->sector);
1204 				if (!raid5_dec_bi_active_stripes(rbi)) {
1205 					rbi->bi_next = return_bi;
1206 					return_bi = rbi;
1207 				}
1208 				rbi = rbi2;
1209 			}
1210 		}
1211 	}
1212 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1213 
1214 	return_io(return_bi);
1215 
1216 	set_bit(STRIPE_HANDLE, &sh->state);
1217 	release_stripe(sh);
1218 }
1219 
1220 static void ops_run_biofill(struct stripe_head *sh)
1221 {
1222 	struct dma_async_tx_descriptor *tx = NULL;
1223 	struct async_submit_ctl submit;
1224 	int i;
1225 
1226 	BUG_ON(sh->batch_head);
1227 	pr_debug("%s: stripe %llu\n", __func__,
1228 		(unsigned long long)sh->sector);
1229 
1230 	for (i = sh->disks; i--; ) {
1231 		struct r5dev *dev = &sh->dev[i];
1232 		if (test_bit(R5_Wantfill, &dev->flags)) {
1233 			struct bio *rbi;
1234 			spin_lock_irq(&sh->stripe_lock);
1235 			dev->read = rbi = dev->toread;
1236 			dev->toread = NULL;
1237 			spin_unlock_irq(&sh->stripe_lock);
1238 			while (rbi && rbi->bi_iter.bi_sector <
1239 				dev->sector + STRIPE_SECTORS) {
1240 				tx = async_copy_data(0, rbi, &dev->page,
1241 					dev->sector, tx, sh);
1242 				rbi = r5_next_bio(rbi, dev->sector);
1243 			}
1244 		}
1245 	}
1246 
1247 	atomic_inc(&sh->count);
1248 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1249 	async_trigger_callback(&submit);
1250 }
1251 
1252 static void mark_target_uptodate(struct stripe_head *sh, int target)
1253 {
1254 	struct r5dev *tgt;
1255 
1256 	if (target < 0)
1257 		return;
1258 
1259 	tgt = &sh->dev[target];
1260 	set_bit(R5_UPTODATE, &tgt->flags);
1261 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1262 	clear_bit(R5_Wantcompute, &tgt->flags);
1263 }
1264 
1265 static void ops_complete_compute(void *stripe_head_ref)
1266 {
1267 	struct stripe_head *sh = stripe_head_ref;
1268 
1269 	pr_debug("%s: stripe %llu\n", __func__,
1270 		(unsigned long long)sh->sector);
1271 
1272 	/* mark the computed target(s) as uptodate */
1273 	mark_target_uptodate(sh, sh->ops.target);
1274 	mark_target_uptodate(sh, sh->ops.target2);
1275 
1276 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1277 	if (sh->check_state == check_state_compute_run)
1278 		sh->check_state = check_state_compute_result;
1279 	set_bit(STRIPE_HANDLE, &sh->state);
1280 	release_stripe(sh);
1281 }
1282 
1283 /* return a pointer to the address conversion region of the scribble buffer */
1284 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1285 				 struct raid5_percpu *percpu, int i)
1286 {
1287 	void *addr;
1288 
1289 	addr = flex_array_get(percpu->scribble, i);
1290 	return addr + sizeof(struct page *) * (sh->disks + 2);
1291 }
1292 
1293 /* return a pointer to the address conversion region of the scribble buffer */
1294 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1295 {
1296 	void *addr;
1297 
1298 	addr = flex_array_get(percpu->scribble, i);
1299 	return addr;
1300 }
1301 
1302 static struct dma_async_tx_descriptor *
1303 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1304 {
1305 	int disks = sh->disks;
1306 	struct page **xor_srcs = to_addr_page(percpu, 0);
1307 	int target = sh->ops.target;
1308 	struct r5dev *tgt = &sh->dev[target];
1309 	struct page *xor_dest = tgt->page;
1310 	int count = 0;
1311 	struct dma_async_tx_descriptor *tx;
1312 	struct async_submit_ctl submit;
1313 	int i;
1314 
1315 	BUG_ON(sh->batch_head);
1316 
1317 	pr_debug("%s: stripe %llu block: %d\n",
1318 		__func__, (unsigned long long)sh->sector, target);
1319 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1320 
1321 	for (i = disks; i--; )
1322 		if (i != target)
1323 			xor_srcs[count++] = sh->dev[i].page;
1324 
1325 	atomic_inc(&sh->count);
1326 
1327 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1328 			  ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1329 	if (unlikely(count == 1))
1330 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1331 	else
1332 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1333 
1334 	return tx;
1335 }
1336 
1337 /* set_syndrome_sources - populate source buffers for gen_syndrome
1338  * @srcs - (struct page *) array of size sh->disks
1339  * @sh - stripe_head to parse
1340  *
1341  * Populates srcs in proper layout order for the stripe and returns the
1342  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1343  * destination buffer is recorded in srcs[count] and the Q destination
1344  * is recorded in srcs[count+1]].
1345  */
1346 static int set_syndrome_sources(struct page **srcs,
1347 				struct stripe_head *sh,
1348 				int srctype)
1349 {
1350 	int disks = sh->disks;
1351 	int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1352 	int d0_idx = raid6_d0(sh);
1353 	int count;
1354 	int i;
1355 
1356 	for (i = 0; i < disks; i++)
1357 		srcs[i] = NULL;
1358 
1359 	count = 0;
1360 	i = d0_idx;
1361 	do {
1362 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1363 		struct r5dev *dev = &sh->dev[i];
1364 
1365 		if (i == sh->qd_idx || i == sh->pd_idx ||
1366 		    (srctype == SYNDROME_SRC_ALL) ||
1367 		    (srctype == SYNDROME_SRC_WANT_DRAIN &&
1368 		     test_bit(R5_Wantdrain, &dev->flags)) ||
1369 		    (srctype == SYNDROME_SRC_WRITTEN &&
1370 		     dev->written))
1371 			srcs[slot] = sh->dev[i].page;
1372 		i = raid6_next_disk(i, disks);
1373 	} while (i != d0_idx);
1374 
1375 	return syndrome_disks;
1376 }
1377 
1378 static struct dma_async_tx_descriptor *
1379 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1380 {
1381 	int disks = sh->disks;
1382 	struct page **blocks = to_addr_page(percpu, 0);
1383 	int target;
1384 	int qd_idx = sh->qd_idx;
1385 	struct dma_async_tx_descriptor *tx;
1386 	struct async_submit_ctl submit;
1387 	struct r5dev *tgt;
1388 	struct page *dest;
1389 	int i;
1390 	int count;
1391 
1392 	BUG_ON(sh->batch_head);
1393 	if (sh->ops.target < 0)
1394 		target = sh->ops.target2;
1395 	else if (sh->ops.target2 < 0)
1396 		target = sh->ops.target;
1397 	else
1398 		/* we should only have one valid target */
1399 		BUG();
1400 	BUG_ON(target < 0);
1401 	pr_debug("%s: stripe %llu block: %d\n",
1402 		__func__, (unsigned long long)sh->sector, target);
1403 
1404 	tgt = &sh->dev[target];
1405 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1406 	dest = tgt->page;
1407 
1408 	atomic_inc(&sh->count);
1409 
1410 	if (target == qd_idx) {
1411 		count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1412 		blocks[count] = NULL; /* regenerating p is not necessary */
1413 		BUG_ON(blocks[count+1] != dest); /* q should already be set */
1414 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1415 				  ops_complete_compute, sh,
1416 				  to_addr_conv(sh, percpu, 0));
1417 		tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1418 	} else {
1419 		/* Compute any data- or p-drive using XOR */
1420 		count = 0;
1421 		for (i = disks; i-- ; ) {
1422 			if (i == target || i == qd_idx)
1423 				continue;
1424 			blocks[count++] = sh->dev[i].page;
1425 		}
1426 
1427 		init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1428 				  NULL, ops_complete_compute, sh,
1429 				  to_addr_conv(sh, percpu, 0));
1430 		tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1431 	}
1432 
1433 	return tx;
1434 }
1435 
1436 static struct dma_async_tx_descriptor *
1437 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1438 {
1439 	int i, count, disks = sh->disks;
1440 	int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1441 	int d0_idx = raid6_d0(sh);
1442 	int faila = -1, failb = -1;
1443 	int target = sh->ops.target;
1444 	int target2 = sh->ops.target2;
1445 	struct r5dev *tgt = &sh->dev[target];
1446 	struct r5dev *tgt2 = &sh->dev[target2];
1447 	struct dma_async_tx_descriptor *tx;
1448 	struct page **blocks = to_addr_page(percpu, 0);
1449 	struct async_submit_ctl submit;
1450 
1451 	BUG_ON(sh->batch_head);
1452 	pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1453 		 __func__, (unsigned long long)sh->sector, target, target2);
1454 	BUG_ON(target < 0 || target2 < 0);
1455 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1456 	BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1457 
1458 	/* we need to open-code set_syndrome_sources to handle the
1459 	 * slot number conversion for 'faila' and 'failb'
1460 	 */
1461 	for (i = 0; i < disks ; i++)
1462 		blocks[i] = NULL;
1463 	count = 0;
1464 	i = d0_idx;
1465 	do {
1466 		int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1467 
1468 		blocks[slot] = sh->dev[i].page;
1469 
1470 		if (i == target)
1471 			faila = slot;
1472 		if (i == target2)
1473 			failb = slot;
1474 		i = raid6_next_disk(i, disks);
1475 	} while (i != d0_idx);
1476 
1477 	BUG_ON(faila == failb);
1478 	if (failb < faila)
1479 		swap(faila, failb);
1480 	pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1481 		 __func__, (unsigned long long)sh->sector, faila, failb);
1482 
1483 	atomic_inc(&sh->count);
1484 
1485 	if (failb == syndrome_disks+1) {
1486 		/* Q disk is one of the missing disks */
1487 		if (faila == syndrome_disks) {
1488 			/* Missing P+Q, just recompute */
1489 			init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1490 					  ops_complete_compute, sh,
1491 					  to_addr_conv(sh, percpu, 0));
1492 			return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1493 						  STRIPE_SIZE, &submit);
1494 		} else {
1495 			struct page *dest;
1496 			int data_target;
1497 			int qd_idx = sh->qd_idx;
1498 
1499 			/* Missing D+Q: recompute D from P, then recompute Q */
1500 			if (target == qd_idx)
1501 				data_target = target2;
1502 			else
1503 				data_target = target;
1504 
1505 			count = 0;
1506 			for (i = disks; i-- ; ) {
1507 				if (i == data_target || i == qd_idx)
1508 					continue;
1509 				blocks[count++] = sh->dev[i].page;
1510 			}
1511 			dest = sh->dev[data_target].page;
1512 			init_async_submit(&submit,
1513 					  ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1514 					  NULL, NULL, NULL,
1515 					  to_addr_conv(sh, percpu, 0));
1516 			tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1517 				       &submit);
1518 
1519 			count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1520 			init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1521 					  ops_complete_compute, sh,
1522 					  to_addr_conv(sh, percpu, 0));
1523 			return async_gen_syndrome(blocks, 0, count+2,
1524 						  STRIPE_SIZE, &submit);
1525 		}
1526 	} else {
1527 		init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1528 				  ops_complete_compute, sh,
1529 				  to_addr_conv(sh, percpu, 0));
1530 		if (failb == syndrome_disks) {
1531 			/* We're missing D+P. */
1532 			return async_raid6_datap_recov(syndrome_disks+2,
1533 						       STRIPE_SIZE, faila,
1534 						       blocks, &submit);
1535 		} else {
1536 			/* We're missing D+D. */
1537 			return async_raid6_2data_recov(syndrome_disks+2,
1538 						       STRIPE_SIZE, faila, failb,
1539 						       blocks, &submit);
1540 		}
1541 	}
1542 }
1543 
1544 static void ops_complete_prexor(void *stripe_head_ref)
1545 {
1546 	struct stripe_head *sh = stripe_head_ref;
1547 
1548 	pr_debug("%s: stripe %llu\n", __func__,
1549 		(unsigned long long)sh->sector);
1550 }
1551 
1552 static struct dma_async_tx_descriptor *
1553 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1554 		struct dma_async_tx_descriptor *tx)
1555 {
1556 	int disks = sh->disks;
1557 	struct page **xor_srcs = to_addr_page(percpu, 0);
1558 	int count = 0, pd_idx = sh->pd_idx, i;
1559 	struct async_submit_ctl submit;
1560 
1561 	/* existing parity data subtracted */
1562 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1563 
1564 	BUG_ON(sh->batch_head);
1565 	pr_debug("%s: stripe %llu\n", __func__,
1566 		(unsigned long long)sh->sector);
1567 
1568 	for (i = disks; i--; ) {
1569 		struct r5dev *dev = &sh->dev[i];
1570 		/* Only process blocks that are known to be uptodate */
1571 		if (test_bit(R5_Wantdrain, &dev->flags))
1572 			xor_srcs[count++] = dev->page;
1573 	}
1574 
1575 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1576 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1577 	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1578 
1579 	return tx;
1580 }
1581 
1582 static struct dma_async_tx_descriptor *
1583 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1584 		struct dma_async_tx_descriptor *tx)
1585 {
1586 	struct page **blocks = to_addr_page(percpu, 0);
1587 	int count;
1588 	struct async_submit_ctl submit;
1589 
1590 	pr_debug("%s: stripe %llu\n", __func__,
1591 		(unsigned long long)sh->sector);
1592 
1593 	count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1594 
1595 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1596 			  ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1597 	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1598 
1599 	return tx;
1600 }
1601 
1602 static struct dma_async_tx_descriptor *
1603 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1604 {
1605 	int disks = sh->disks;
1606 	int i;
1607 	struct stripe_head *head_sh = sh;
1608 
1609 	pr_debug("%s: stripe %llu\n", __func__,
1610 		(unsigned long long)sh->sector);
1611 
1612 	for (i = disks; i--; ) {
1613 		struct r5dev *dev;
1614 		struct bio *chosen;
1615 
1616 		sh = head_sh;
1617 		if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1618 			struct bio *wbi;
1619 
1620 again:
1621 			dev = &sh->dev[i];
1622 			spin_lock_irq(&sh->stripe_lock);
1623 			chosen = dev->towrite;
1624 			dev->towrite = NULL;
1625 			sh->overwrite_disks = 0;
1626 			BUG_ON(dev->written);
1627 			wbi = dev->written = chosen;
1628 			spin_unlock_irq(&sh->stripe_lock);
1629 			WARN_ON(dev->page != dev->orig_page);
1630 
1631 			while (wbi && wbi->bi_iter.bi_sector <
1632 				dev->sector + STRIPE_SECTORS) {
1633 				if (wbi->bi_rw & REQ_FUA)
1634 					set_bit(R5_WantFUA, &dev->flags);
1635 				if (wbi->bi_rw & REQ_SYNC)
1636 					set_bit(R5_SyncIO, &dev->flags);
1637 				if (wbi->bi_rw & REQ_DISCARD)
1638 					set_bit(R5_Discard, &dev->flags);
1639 				else {
1640 					tx = async_copy_data(1, wbi, &dev->page,
1641 						dev->sector, tx, sh);
1642 					if (dev->page != dev->orig_page) {
1643 						set_bit(R5_SkipCopy, &dev->flags);
1644 						clear_bit(R5_UPTODATE, &dev->flags);
1645 						clear_bit(R5_OVERWRITE, &dev->flags);
1646 					}
1647 				}
1648 				wbi = r5_next_bio(wbi, dev->sector);
1649 			}
1650 
1651 			if (head_sh->batch_head) {
1652 				sh = list_first_entry(&sh->batch_list,
1653 						      struct stripe_head,
1654 						      batch_list);
1655 				if (sh == head_sh)
1656 					continue;
1657 				goto again;
1658 			}
1659 		}
1660 	}
1661 
1662 	return tx;
1663 }
1664 
1665 static void ops_complete_reconstruct(void *stripe_head_ref)
1666 {
1667 	struct stripe_head *sh = stripe_head_ref;
1668 	int disks = sh->disks;
1669 	int pd_idx = sh->pd_idx;
1670 	int qd_idx = sh->qd_idx;
1671 	int i;
1672 	bool fua = false, sync = false, discard = false;
1673 
1674 	pr_debug("%s: stripe %llu\n", __func__,
1675 		(unsigned long long)sh->sector);
1676 
1677 	for (i = disks; i--; ) {
1678 		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1679 		sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1680 		discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1681 	}
1682 
1683 	for (i = disks; i--; ) {
1684 		struct r5dev *dev = &sh->dev[i];
1685 
1686 		if (dev->written || i == pd_idx || i == qd_idx) {
1687 			if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1688 				set_bit(R5_UPTODATE, &dev->flags);
1689 			if (fua)
1690 				set_bit(R5_WantFUA, &dev->flags);
1691 			if (sync)
1692 				set_bit(R5_SyncIO, &dev->flags);
1693 		}
1694 	}
1695 
1696 	if (sh->reconstruct_state == reconstruct_state_drain_run)
1697 		sh->reconstruct_state = reconstruct_state_drain_result;
1698 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1699 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1700 	else {
1701 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1702 		sh->reconstruct_state = reconstruct_state_result;
1703 	}
1704 
1705 	set_bit(STRIPE_HANDLE, &sh->state);
1706 	release_stripe(sh);
1707 }
1708 
1709 static void
1710 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1711 		     struct dma_async_tx_descriptor *tx)
1712 {
1713 	int disks = sh->disks;
1714 	struct page **xor_srcs;
1715 	struct async_submit_ctl submit;
1716 	int count, pd_idx = sh->pd_idx, i;
1717 	struct page *xor_dest;
1718 	int prexor = 0;
1719 	unsigned long flags;
1720 	int j = 0;
1721 	struct stripe_head *head_sh = sh;
1722 	int last_stripe;
1723 
1724 	pr_debug("%s: stripe %llu\n", __func__,
1725 		(unsigned long long)sh->sector);
1726 
1727 	for (i = 0; i < sh->disks; i++) {
1728 		if (pd_idx == i)
1729 			continue;
1730 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1731 			break;
1732 	}
1733 	if (i >= sh->disks) {
1734 		atomic_inc(&sh->count);
1735 		set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1736 		ops_complete_reconstruct(sh);
1737 		return;
1738 	}
1739 again:
1740 	count = 0;
1741 	xor_srcs = to_addr_page(percpu, j);
1742 	/* check if prexor is active which means only process blocks
1743 	 * that are part of a read-modify-write (written)
1744 	 */
1745 	if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1746 		prexor = 1;
1747 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1748 		for (i = disks; i--; ) {
1749 			struct r5dev *dev = &sh->dev[i];
1750 			if (head_sh->dev[i].written)
1751 				xor_srcs[count++] = dev->page;
1752 		}
1753 	} else {
1754 		xor_dest = sh->dev[pd_idx].page;
1755 		for (i = disks; i--; ) {
1756 			struct r5dev *dev = &sh->dev[i];
1757 			if (i != pd_idx)
1758 				xor_srcs[count++] = dev->page;
1759 		}
1760 	}
1761 
1762 	/* 1/ if we prexor'd then the dest is reused as a source
1763 	 * 2/ if we did not prexor then we are redoing the parity
1764 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1765 	 * for the synchronous xor case
1766 	 */
1767 	last_stripe = !head_sh->batch_head ||
1768 		list_first_entry(&sh->batch_list,
1769 				 struct stripe_head, batch_list) == head_sh;
1770 	if (last_stripe) {
1771 		flags = ASYNC_TX_ACK |
1772 			(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1773 
1774 		atomic_inc(&head_sh->count);
1775 		init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1776 				  to_addr_conv(sh, percpu, j));
1777 	} else {
1778 		flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1779 		init_async_submit(&submit, flags, tx, NULL, NULL,
1780 				  to_addr_conv(sh, percpu, j));
1781 	}
1782 
1783 	if (unlikely(count == 1))
1784 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1785 	else
1786 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1787 	if (!last_stripe) {
1788 		j++;
1789 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1790 				      batch_list);
1791 		goto again;
1792 	}
1793 }
1794 
1795 static void
1796 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1797 		     struct dma_async_tx_descriptor *tx)
1798 {
1799 	struct async_submit_ctl submit;
1800 	struct page **blocks;
1801 	int count, i, j = 0;
1802 	struct stripe_head *head_sh = sh;
1803 	int last_stripe;
1804 	int synflags;
1805 	unsigned long txflags;
1806 
1807 	pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1808 
1809 	for (i = 0; i < sh->disks; i++) {
1810 		if (sh->pd_idx == i || sh->qd_idx == i)
1811 			continue;
1812 		if (!test_bit(R5_Discard, &sh->dev[i].flags))
1813 			break;
1814 	}
1815 	if (i >= sh->disks) {
1816 		atomic_inc(&sh->count);
1817 		set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1818 		set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1819 		ops_complete_reconstruct(sh);
1820 		return;
1821 	}
1822 
1823 again:
1824 	blocks = to_addr_page(percpu, j);
1825 
1826 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1827 		synflags = SYNDROME_SRC_WRITTEN;
1828 		txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1829 	} else {
1830 		synflags = SYNDROME_SRC_ALL;
1831 		txflags = ASYNC_TX_ACK;
1832 	}
1833 
1834 	count = set_syndrome_sources(blocks, sh, synflags);
1835 	last_stripe = !head_sh->batch_head ||
1836 		list_first_entry(&sh->batch_list,
1837 				 struct stripe_head, batch_list) == head_sh;
1838 
1839 	if (last_stripe) {
1840 		atomic_inc(&head_sh->count);
1841 		init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1842 				  head_sh, to_addr_conv(sh, percpu, j));
1843 	} else
1844 		init_async_submit(&submit, 0, tx, NULL, NULL,
1845 				  to_addr_conv(sh, percpu, j));
1846 	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1847 	if (!last_stripe) {
1848 		j++;
1849 		sh = list_first_entry(&sh->batch_list, struct stripe_head,
1850 				      batch_list);
1851 		goto again;
1852 	}
1853 }
1854 
1855 static void ops_complete_check(void *stripe_head_ref)
1856 {
1857 	struct stripe_head *sh = stripe_head_ref;
1858 
1859 	pr_debug("%s: stripe %llu\n", __func__,
1860 		(unsigned long long)sh->sector);
1861 
1862 	sh->check_state = check_state_check_result;
1863 	set_bit(STRIPE_HANDLE, &sh->state);
1864 	release_stripe(sh);
1865 }
1866 
1867 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1868 {
1869 	int disks = sh->disks;
1870 	int pd_idx = sh->pd_idx;
1871 	int qd_idx = sh->qd_idx;
1872 	struct page *xor_dest;
1873 	struct page **xor_srcs = to_addr_page(percpu, 0);
1874 	struct dma_async_tx_descriptor *tx;
1875 	struct async_submit_ctl submit;
1876 	int count;
1877 	int i;
1878 
1879 	pr_debug("%s: stripe %llu\n", __func__,
1880 		(unsigned long long)sh->sector);
1881 
1882 	BUG_ON(sh->batch_head);
1883 	count = 0;
1884 	xor_dest = sh->dev[pd_idx].page;
1885 	xor_srcs[count++] = xor_dest;
1886 	for (i = disks; i--; ) {
1887 		if (i == pd_idx || i == qd_idx)
1888 			continue;
1889 		xor_srcs[count++] = sh->dev[i].page;
1890 	}
1891 
1892 	init_async_submit(&submit, 0, NULL, NULL, NULL,
1893 			  to_addr_conv(sh, percpu, 0));
1894 	tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1895 			   &sh->ops.zero_sum_result, &submit);
1896 
1897 	atomic_inc(&sh->count);
1898 	init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1899 	tx = async_trigger_callback(&submit);
1900 }
1901 
1902 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1903 {
1904 	struct page **srcs = to_addr_page(percpu, 0);
1905 	struct async_submit_ctl submit;
1906 	int count;
1907 
1908 	pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1909 		(unsigned long long)sh->sector, checkp);
1910 
1911 	BUG_ON(sh->batch_head);
1912 	count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
1913 	if (!checkp)
1914 		srcs[count] = NULL;
1915 
1916 	atomic_inc(&sh->count);
1917 	init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1918 			  sh, to_addr_conv(sh, percpu, 0));
1919 	async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1920 			   &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1921 }
1922 
1923 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1924 {
1925 	int overlap_clear = 0, i, disks = sh->disks;
1926 	struct dma_async_tx_descriptor *tx = NULL;
1927 	struct r5conf *conf = sh->raid_conf;
1928 	int level = conf->level;
1929 	struct raid5_percpu *percpu;
1930 	unsigned long cpu;
1931 
1932 	cpu = get_cpu();
1933 	percpu = per_cpu_ptr(conf->percpu, cpu);
1934 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1935 		ops_run_biofill(sh);
1936 		overlap_clear++;
1937 	}
1938 
1939 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1940 		if (level < 6)
1941 			tx = ops_run_compute5(sh, percpu);
1942 		else {
1943 			if (sh->ops.target2 < 0 || sh->ops.target < 0)
1944 				tx = ops_run_compute6_1(sh, percpu);
1945 			else
1946 				tx = ops_run_compute6_2(sh, percpu);
1947 		}
1948 		/* terminate the chain if reconstruct is not set to be run */
1949 		if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1950 			async_tx_ack(tx);
1951 	}
1952 
1953 	if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
1954 		if (level < 6)
1955 			tx = ops_run_prexor5(sh, percpu, tx);
1956 		else
1957 			tx = ops_run_prexor6(sh, percpu, tx);
1958 	}
1959 
1960 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1961 		tx = ops_run_biodrain(sh, tx);
1962 		overlap_clear++;
1963 	}
1964 
1965 	if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1966 		if (level < 6)
1967 			ops_run_reconstruct5(sh, percpu, tx);
1968 		else
1969 			ops_run_reconstruct6(sh, percpu, tx);
1970 	}
1971 
1972 	if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1973 		if (sh->check_state == check_state_run)
1974 			ops_run_check_p(sh, percpu);
1975 		else if (sh->check_state == check_state_run_q)
1976 			ops_run_check_pq(sh, percpu, 0);
1977 		else if (sh->check_state == check_state_run_pq)
1978 			ops_run_check_pq(sh, percpu, 1);
1979 		else
1980 			BUG();
1981 	}
1982 
1983 	if (overlap_clear && !sh->batch_head)
1984 		for (i = disks; i--; ) {
1985 			struct r5dev *dev = &sh->dev[i];
1986 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
1987 				wake_up(&sh->raid_conf->wait_for_overlap);
1988 		}
1989 	put_cpu();
1990 }
1991 
1992 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp)
1993 {
1994 	struct stripe_head *sh;
1995 
1996 	sh = kmem_cache_zalloc(sc, gfp);
1997 	if (sh) {
1998 		spin_lock_init(&sh->stripe_lock);
1999 		spin_lock_init(&sh->batch_lock);
2000 		INIT_LIST_HEAD(&sh->batch_list);
2001 		INIT_LIST_HEAD(&sh->lru);
2002 		atomic_set(&sh->count, 1);
2003 	}
2004 	return sh;
2005 }
2006 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2007 {
2008 	struct stripe_head *sh;
2009 
2010 	sh = alloc_stripe(conf->slab_cache, gfp);
2011 	if (!sh)
2012 		return 0;
2013 
2014 	sh->raid_conf = conf;
2015 
2016 	if (grow_buffers(sh, gfp)) {
2017 		shrink_buffers(sh);
2018 		kmem_cache_free(conf->slab_cache, sh);
2019 		return 0;
2020 	}
2021 	sh->hash_lock_index =
2022 		conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2023 	/* we just created an active stripe so... */
2024 	atomic_inc(&conf->active_stripes);
2025 
2026 	release_stripe(sh);
2027 	conf->max_nr_stripes++;
2028 	return 1;
2029 }
2030 
2031 static int grow_stripes(struct r5conf *conf, int num)
2032 {
2033 	struct kmem_cache *sc;
2034 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
2035 
2036 	if (conf->mddev->gendisk)
2037 		sprintf(conf->cache_name[0],
2038 			"raid%d-%s", conf->level, mdname(conf->mddev));
2039 	else
2040 		sprintf(conf->cache_name[0],
2041 			"raid%d-%p", conf->level, conf->mddev);
2042 	sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
2043 
2044 	conf->active_name = 0;
2045 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
2046 			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2047 			       0, 0, NULL);
2048 	if (!sc)
2049 		return 1;
2050 	conf->slab_cache = sc;
2051 	conf->pool_size = devs;
2052 	while (num--)
2053 		if (!grow_one_stripe(conf, GFP_KERNEL))
2054 			return 1;
2055 
2056 	return 0;
2057 }
2058 
2059 /**
2060  * scribble_len - return the required size of the scribble region
2061  * @num - total number of disks in the array
2062  *
2063  * The size must be enough to contain:
2064  * 1/ a struct page pointer for each device in the array +2
2065  * 2/ room to convert each entry in (1) to its corresponding dma
2066  *    (dma_map_page()) or page (page_address()) address.
2067  *
2068  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2069  * calculate over all devices (not just the data blocks), using zeros in place
2070  * of the P and Q blocks.
2071  */
2072 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2073 {
2074 	struct flex_array *ret;
2075 	size_t len;
2076 
2077 	len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2078 	ret = flex_array_alloc(len, cnt, flags);
2079 	if (!ret)
2080 		return NULL;
2081 	/* always prealloc all elements, so no locking is required */
2082 	if (flex_array_prealloc(ret, 0, cnt, flags)) {
2083 		flex_array_free(ret);
2084 		return NULL;
2085 	}
2086 	return ret;
2087 }
2088 
2089 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2090 {
2091 	unsigned long cpu;
2092 	int err = 0;
2093 
2094 	mddev_suspend(conf->mddev);
2095 	get_online_cpus();
2096 	for_each_present_cpu(cpu) {
2097 		struct raid5_percpu *percpu;
2098 		struct flex_array *scribble;
2099 
2100 		percpu = per_cpu_ptr(conf->percpu, cpu);
2101 		scribble = scribble_alloc(new_disks,
2102 					  new_sectors / STRIPE_SECTORS,
2103 					  GFP_NOIO);
2104 
2105 		if (scribble) {
2106 			flex_array_free(percpu->scribble);
2107 			percpu->scribble = scribble;
2108 		} else {
2109 			err = -ENOMEM;
2110 			break;
2111 		}
2112 	}
2113 	put_online_cpus();
2114 	mddev_resume(conf->mddev);
2115 	return err;
2116 }
2117 
2118 static int resize_stripes(struct r5conf *conf, int newsize)
2119 {
2120 	/* Make all the stripes able to hold 'newsize' devices.
2121 	 * New slots in each stripe get 'page' set to a new page.
2122 	 *
2123 	 * This happens in stages:
2124 	 * 1/ create a new kmem_cache and allocate the required number of
2125 	 *    stripe_heads.
2126 	 * 2/ gather all the old stripe_heads and transfer the pages across
2127 	 *    to the new stripe_heads.  This will have the side effect of
2128 	 *    freezing the array as once all stripe_heads have been collected,
2129 	 *    no IO will be possible.  Old stripe heads are freed once their
2130 	 *    pages have been transferred over, and the old kmem_cache is
2131 	 *    freed when all stripes are done.
2132 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2133 	 *    we simple return a failre status - no need to clean anything up.
2134 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
2135 	 *    If this fails, we don't bother trying the shrink the
2136 	 *    stripe_heads down again, we just leave them as they are.
2137 	 *    As each stripe_head is processed the new one is released into
2138 	 *    active service.
2139 	 *
2140 	 * Once step2 is started, we cannot afford to wait for a write,
2141 	 * so we use GFP_NOIO allocations.
2142 	 */
2143 	struct stripe_head *osh, *nsh;
2144 	LIST_HEAD(newstripes);
2145 	struct disk_info *ndisks;
2146 	int err;
2147 	struct kmem_cache *sc;
2148 	int i;
2149 	int hash, cnt;
2150 
2151 	if (newsize <= conf->pool_size)
2152 		return 0; /* never bother to shrink */
2153 
2154 	err = md_allow_write(conf->mddev);
2155 	if (err)
2156 		return err;
2157 
2158 	/* Step 1 */
2159 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2160 			       sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2161 			       0, 0, NULL);
2162 	if (!sc)
2163 		return -ENOMEM;
2164 
2165 	/* Need to ensure auto-resizing doesn't interfere */
2166 	mutex_lock(&conf->cache_size_mutex);
2167 
2168 	for (i = conf->max_nr_stripes; i; i--) {
2169 		nsh = alloc_stripe(sc, GFP_KERNEL);
2170 		if (!nsh)
2171 			break;
2172 
2173 		nsh->raid_conf = conf;
2174 		list_add(&nsh->lru, &newstripes);
2175 	}
2176 	if (i) {
2177 		/* didn't get enough, give up */
2178 		while (!list_empty(&newstripes)) {
2179 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
2180 			list_del(&nsh->lru);
2181 			kmem_cache_free(sc, nsh);
2182 		}
2183 		kmem_cache_destroy(sc);
2184 		mutex_unlock(&conf->cache_size_mutex);
2185 		return -ENOMEM;
2186 	}
2187 	/* Step 2 - Must use GFP_NOIO now.
2188 	 * OK, we have enough stripes, start collecting inactive
2189 	 * stripes and copying them over
2190 	 */
2191 	hash = 0;
2192 	cnt = 0;
2193 	list_for_each_entry(nsh, &newstripes, lru) {
2194 		lock_device_hash_lock(conf, hash);
2195 		wait_event_exclusive_cmd(conf->wait_for_stripe[hash],
2196 				    !list_empty(conf->inactive_list + hash),
2197 				    unlock_device_hash_lock(conf, hash),
2198 				    lock_device_hash_lock(conf, hash));
2199 		osh = get_free_stripe(conf, hash);
2200 		unlock_device_hash_lock(conf, hash);
2201 
2202 		for(i=0; i<conf->pool_size; i++) {
2203 			nsh->dev[i].page = osh->dev[i].page;
2204 			nsh->dev[i].orig_page = osh->dev[i].page;
2205 		}
2206 		nsh->hash_lock_index = hash;
2207 		kmem_cache_free(conf->slab_cache, osh);
2208 		cnt++;
2209 		if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2210 		    !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2211 			hash++;
2212 			cnt = 0;
2213 		}
2214 	}
2215 	kmem_cache_destroy(conf->slab_cache);
2216 
2217 	/* Step 3.
2218 	 * At this point, we are holding all the stripes so the array
2219 	 * is completely stalled, so now is a good time to resize
2220 	 * conf->disks and the scribble region
2221 	 */
2222 	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2223 	if (ndisks) {
2224 		for (i=0; i<conf->raid_disks; i++)
2225 			ndisks[i] = conf->disks[i];
2226 		kfree(conf->disks);
2227 		conf->disks = ndisks;
2228 	} else
2229 		err = -ENOMEM;
2230 
2231 	mutex_unlock(&conf->cache_size_mutex);
2232 	/* Step 4, return new stripes to service */
2233 	while(!list_empty(&newstripes)) {
2234 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
2235 		list_del_init(&nsh->lru);
2236 
2237 		for (i=conf->raid_disks; i < newsize; i++)
2238 			if (nsh->dev[i].page == NULL) {
2239 				struct page *p = alloc_page(GFP_NOIO);
2240 				nsh->dev[i].page = p;
2241 				nsh->dev[i].orig_page = p;
2242 				if (!p)
2243 					err = -ENOMEM;
2244 			}
2245 		release_stripe(nsh);
2246 	}
2247 	/* critical section pass, GFP_NOIO no longer needed */
2248 
2249 	conf->slab_cache = sc;
2250 	conf->active_name = 1-conf->active_name;
2251 	if (!err)
2252 		conf->pool_size = newsize;
2253 	return err;
2254 }
2255 
2256 static int drop_one_stripe(struct r5conf *conf)
2257 {
2258 	struct stripe_head *sh;
2259 	int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2260 
2261 	spin_lock_irq(conf->hash_locks + hash);
2262 	sh = get_free_stripe(conf, hash);
2263 	spin_unlock_irq(conf->hash_locks + hash);
2264 	if (!sh)
2265 		return 0;
2266 	BUG_ON(atomic_read(&sh->count));
2267 	shrink_buffers(sh);
2268 	kmem_cache_free(conf->slab_cache, sh);
2269 	atomic_dec(&conf->active_stripes);
2270 	conf->max_nr_stripes--;
2271 	return 1;
2272 }
2273 
2274 static void shrink_stripes(struct r5conf *conf)
2275 {
2276 	while (conf->max_nr_stripes &&
2277 	       drop_one_stripe(conf))
2278 		;
2279 
2280 	if (conf->slab_cache)
2281 		kmem_cache_destroy(conf->slab_cache);
2282 	conf->slab_cache = NULL;
2283 }
2284 
2285 static void raid5_end_read_request(struct bio * bi, int error)
2286 {
2287 	struct stripe_head *sh = bi->bi_private;
2288 	struct r5conf *conf = sh->raid_conf;
2289 	int disks = sh->disks, i;
2290 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
2291 	char b[BDEVNAME_SIZE];
2292 	struct md_rdev *rdev = NULL;
2293 	sector_t s;
2294 
2295 	for (i=0 ; i<disks; i++)
2296 		if (bi == &sh->dev[i].req)
2297 			break;
2298 
2299 	pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
2300 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2301 		uptodate);
2302 	if (i == disks) {
2303 		BUG();
2304 		return;
2305 	}
2306 	if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2307 		/* If replacement finished while this request was outstanding,
2308 		 * 'replacement' might be NULL already.
2309 		 * In that case it moved down to 'rdev'.
2310 		 * rdev is not removed until all requests are finished.
2311 		 */
2312 		rdev = conf->disks[i].replacement;
2313 	if (!rdev)
2314 		rdev = conf->disks[i].rdev;
2315 
2316 	if (use_new_offset(conf, sh))
2317 		s = sh->sector + rdev->new_data_offset;
2318 	else
2319 		s = sh->sector + rdev->data_offset;
2320 	if (uptodate) {
2321 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
2322 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2323 			/* Note that this cannot happen on a
2324 			 * replacement device.  We just fail those on
2325 			 * any error
2326 			 */
2327 			printk_ratelimited(
2328 				KERN_INFO
2329 				"md/raid:%s: read error corrected"
2330 				" (%lu sectors at %llu on %s)\n",
2331 				mdname(conf->mddev), STRIPE_SECTORS,
2332 				(unsigned long long)s,
2333 				bdevname(rdev->bdev, b));
2334 			atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2335 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2336 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2337 		} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2338 			clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2339 
2340 		if (atomic_read(&rdev->read_errors))
2341 			atomic_set(&rdev->read_errors, 0);
2342 	} else {
2343 		const char *bdn = bdevname(rdev->bdev, b);
2344 		int retry = 0;
2345 		int set_bad = 0;
2346 
2347 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2348 		atomic_inc(&rdev->read_errors);
2349 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2350 			printk_ratelimited(
2351 				KERN_WARNING
2352 				"md/raid:%s: read error on replacement device "
2353 				"(sector %llu on %s).\n",
2354 				mdname(conf->mddev),
2355 				(unsigned long long)s,
2356 				bdn);
2357 		else if (conf->mddev->degraded >= conf->max_degraded) {
2358 			set_bad = 1;
2359 			printk_ratelimited(
2360 				KERN_WARNING
2361 				"md/raid:%s: read error not correctable "
2362 				"(sector %llu on %s).\n",
2363 				mdname(conf->mddev),
2364 				(unsigned long long)s,
2365 				bdn);
2366 		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2367 			/* Oh, no!!! */
2368 			set_bad = 1;
2369 			printk_ratelimited(
2370 				KERN_WARNING
2371 				"md/raid:%s: read error NOT corrected!! "
2372 				"(sector %llu on %s).\n",
2373 				mdname(conf->mddev),
2374 				(unsigned long long)s,
2375 				bdn);
2376 		} else if (atomic_read(&rdev->read_errors)
2377 			 > conf->max_nr_stripes)
2378 			printk(KERN_WARNING
2379 			       "md/raid:%s: Too many read errors, failing device %s.\n",
2380 			       mdname(conf->mddev), bdn);
2381 		else
2382 			retry = 1;
2383 		if (set_bad && test_bit(In_sync, &rdev->flags)
2384 		    && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2385 			retry = 1;
2386 		if (retry)
2387 			if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2388 				set_bit(R5_ReadError, &sh->dev[i].flags);
2389 				clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2390 			} else
2391 				set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2392 		else {
2393 			clear_bit(R5_ReadError, &sh->dev[i].flags);
2394 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
2395 			if (!(set_bad
2396 			      && test_bit(In_sync, &rdev->flags)
2397 			      && rdev_set_badblocks(
2398 				      rdev, sh->sector, STRIPE_SECTORS, 0)))
2399 				md_error(conf->mddev, rdev);
2400 		}
2401 	}
2402 	rdev_dec_pending(rdev, conf->mddev);
2403 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
2404 	set_bit(STRIPE_HANDLE, &sh->state);
2405 	release_stripe(sh);
2406 }
2407 
2408 static void raid5_end_write_request(struct bio *bi, int error)
2409 {
2410 	struct stripe_head *sh = bi->bi_private;
2411 	struct r5conf *conf = sh->raid_conf;
2412 	int disks = sh->disks, i;
2413 	struct md_rdev *uninitialized_var(rdev);
2414 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
2415 	sector_t first_bad;
2416 	int bad_sectors;
2417 	int replacement = 0;
2418 
2419 	for (i = 0 ; i < disks; i++) {
2420 		if (bi == &sh->dev[i].req) {
2421 			rdev = conf->disks[i].rdev;
2422 			break;
2423 		}
2424 		if (bi == &sh->dev[i].rreq) {
2425 			rdev = conf->disks[i].replacement;
2426 			if (rdev)
2427 				replacement = 1;
2428 			else
2429 				/* rdev was removed and 'replacement'
2430 				 * replaced it.  rdev is not removed
2431 				 * until all requests are finished.
2432 				 */
2433 				rdev = conf->disks[i].rdev;
2434 			break;
2435 		}
2436 	}
2437 	pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
2438 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
2439 		uptodate);
2440 	if (i == disks) {
2441 		BUG();
2442 		return;
2443 	}
2444 
2445 	if (replacement) {
2446 		if (!uptodate)
2447 			md_error(conf->mddev, rdev);
2448 		else if (is_badblock(rdev, sh->sector,
2449 				     STRIPE_SECTORS,
2450 				     &first_bad, &bad_sectors))
2451 			set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2452 	} else {
2453 		if (!uptodate) {
2454 			set_bit(STRIPE_DEGRADED, &sh->state);
2455 			set_bit(WriteErrorSeen, &rdev->flags);
2456 			set_bit(R5_WriteError, &sh->dev[i].flags);
2457 			if (!test_and_set_bit(WantReplacement, &rdev->flags))
2458 				set_bit(MD_RECOVERY_NEEDED,
2459 					&rdev->mddev->recovery);
2460 		} else if (is_badblock(rdev, sh->sector,
2461 				       STRIPE_SECTORS,
2462 				       &first_bad, &bad_sectors)) {
2463 			set_bit(R5_MadeGood, &sh->dev[i].flags);
2464 			if (test_bit(R5_ReadError, &sh->dev[i].flags))
2465 				/* That was a successful write so make
2466 				 * sure it looks like we already did
2467 				 * a re-write.
2468 				 */
2469 				set_bit(R5_ReWrite, &sh->dev[i].flags);
2470 		}
2471 	}
2472 	rdev_dec_pending(rdev, conf->mddev);
2473 
2474 	if (sh->batch_head && !uptodate && !replacement)
2475 		set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2476 
2477 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2478 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
2479 	set_bit(STRIPE_HANDLE, &sh->state);
2480 	release_stripe(sh);
2481 
2482 	if (sh->batch_head && sh != sh->batch_head)
2483 		release_stripe(sh->batch_head);
2484 }
2485 
2486 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
2487 
2488 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2489 {
2490 	struct r5dev *dev = &sh->dev[i];
2491 
2492 	bio_init(&dev->req);
2493 	dev->req.bi_io_vec = &dev->vec;
2494 	dev->req.bi_max_vecs = 1;
2495 	dev->req.bi_private = sh;
2496 
2497 	bio_init(&dev->rreq);
2498 	dev->rreq.bi_io_vec = &dev->rvec;
2499 	dev->rreq.bi_max_vecs = 1;
2500 	dev->rreq.bi_private = sh;
2501 
2502 	dev->flags = 0;
2503 	dev->sector = compute_blocknr(sh, i, previous);
2504 }
2505 
2506 static void error(struct mddev *mddev, struct md_rdev *rdev)
2507 {
2508 	char b[BDEVNAME_SIZE];
2509 	struct r5conf *conf = mddev->private;
2510 	unsigned long flags;
2511 	pr_debug("raid456: error called\n");
2512 
2513 	spin_lock_irqsave(&conf->device_lock, flags);
2514 	clear_bit(In_sync, &rdev->flags);
2515 	mddev->degraded = calc_degraded(conf);
2516 	spin_unlock_irqrestore(&conf->device_lock, flags);
2517 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2518 
2519 	set_bit(Blocked, &rdev->flags);
2520 	set_bit(Faulty, &rdev->flags);
2521 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
2522 	printk(KERN_ALERT
2523 	       "md/raid:%s: Disk failure on %s, disabling device.\n"
2524 	       "md/raid:%s: Operation continuing on %d devices.\n",
2525 	       mdname(mddev),
2526 	       bdevname(rdev->bdev, b),
2527 	       mdname(mddev),
2528 	       conf->raid_disks - mddev->degraded);
2529 }
2530 
2531 /*
2532  * Input: a 'big' sector number,
2533  * Output: index of the data and parity disk, and the sector # in them.
2534  */
2535 static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2536 				     int previous, int *dd_idx,
2537 				     struct stripe_head *sh)
2538 {
2539 	sector_t stripe, stripe2;
2540 	sector_t chunk_number;
2541 	unsigned int chunk_offset;
2542 	int pd_idx, qd_idx;
2543 	int ddf_layout = 0;
2544 	sector_t new_sector;
2545 	int algorithm = previous ? conf->prev_algo
2546 				 : conf->algorithm;
2547 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2548 					 : conf->chunk_sectors;
2549 	int raid_disks = previous ? conf->previous_raid_disks
2550 				  : conf->raid_disks;
2551 	int data_disks = raid_disks - conf->max_degraded;
2552 
2553 	/* First compute the information on this sector */
2554 
2555 	/*
2556 	 * Compute the chunk number and the sector offset inside the chunk
2557 	 */
2558 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
2559 	chunk_number = r_sector;
2560 
2561 	/*
2562 	 * Compute the stripe number
2563 	 */
2564 	stripe = chunk_number;
2565 	*dd_idx = sector_div(stripe, data_disks);
2566 	stripe2 = stripe;
2567 	/*
2568 	 * Select the parity disk based on the user selected algorithm.
2569 	 */
2570 	pd_idx = qd_idx = -1;
2571 	switch(conf->level) {
2572 	case 4:
2573 		pd_idx = data_disks;
2574 		break;
2575 	case 5:
2576 		switch (algorithm) {
2577 		case ALGORITHM_LEFT_ASYMMETRIC:
2578 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2579 			if (*dd_idx >= pd_idx)
2580 				(*dd_idx)++;
2581 			break;
2582 		case ALGORITHM_RIGHT_ASYMMETRIC:
2583 			pd_idx = sector_div(stripe2, raid_disks);
2584 			if (*dd_idx >= pd_idx)
2585 				(*dd_idx)++;
2586 			break;
2587 		case ALGORITHM_LEFT_SYMMETRIC:
2588 			pd_idx = data_disks - sector_div(stripe2, raid_disks);
2589 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2590 			break;
2591 		case ALGORITHM_RIGHT_SYMMETRIC:
2592 			pd_idx = sector_div(stripe2, raid_disks);
2593 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2594 			break;
2595 		case ALGORITHM_PARITY_0:
2596 			pd_idx = 0;
2597 			(*dd_idx)++;
2598 			break;
2599 		case ALGORITHM_PARITY_N:
2600 			pd_idx = data_disks;
2601 			break;
2602 		default:
2603 			BUG();
2604 		}
2605 		break;
2606 	case 6:
2607 
2608 		switch (algorithm) {
2609 		case ALGORITHM_LEFT_ASYMMETRIC:
2610 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2611 			qd_idx = pd_idx + 1;
2612 			if (pd_idx == raid_disks-1) {
2613 				(*dd_idx)++;	/* Q D D D P */
2614 				qd_idx = 0;
2615 			} else if (*dd_idx >= pd_idx)
2616 				(*dd_idx) += 2; /* D D P Q D */
2617 			break;
2618 		case ALGORITHM_RIGHT_ASYMMETRIC:
2619 			pd_idx = sector_div(stripe2, raid_disks);
2620 			qd_idx = pd_idx + 1;
2621 			if (pd_idx == raid_disks-1) {
2622 				(*dd_idx)++;	/* Q D D D P */
2623 				qd_idx = 0;
2624 			} else if (*dd_idx >= pd_idx)
2625 				(*dd_idx) += 2; /* D D P Q D */
2626 			break;
2627 		case ALGORITHM_LEFT_SYMMETRIC:
2628 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2629 			qd_idx = (pd_idx + 1) % raid_disks;
2630 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2631 			break;
2632 		case ALGORITHM_RIGHT_SYMMETRIC:
2633 			pd_idx = sector_div(stripe2, raid_disks);
2634 			qd_idx = (pd_idx + 1) % raid_disks;
2635 			*dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2636 			break;
2637 
2638 		case ALGORITHM_PARITY_0:
2639 			pd_idx = 0;
2640 			qd_idx = 1;
2641 			(*dd_idx) += 2;
2642 			break;
2643 		case ALGORITHM_PARITY_N:
2644 			pd_idx = data_disks;
2645 			qd_idx = data_disks + 1;
2646 			break;
2647 
2648 		case ALGORITHM_ROTATING_ZERO_RESTART:
2649 			/* Exactly the same as RIGHT_ASYMMETRIC, but or
2650 			 * of blocks for computing Q is different.
2651 			 */
2652 			pd_idx = sector_div(stripe2, raid_disks);
2653 			qd_idx = pd_idx + 1;
2654 			if (pd_idx == raid_disks-1) {
2655 				(*dd_idx)++;	/* Q D D D P */
2656 				qd_idx = 0;
2657 			} else if (*dd_idx >= pd_idx)
2658 				(*dd_idx) += 2; /* D D P Q D */
2659 			ddf_layout = 1;
2660 			break;
2661 
2662 		case ALGORITHM_ROTATING_N_RESTART:
2663 			/* Same a left_asymmetric, by first stripe is
2664 			 * D D D P Q  rather than
2665 			 * Q D D D P
2666 			 */
2667 			stripe2 += 1;
2668 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2669 			qd_idx = pd_idx + 1;
2670 			if (pd_idx == raid_disks-1) {
2671 				(*dd_idx)++;	/* Q D D D P */
2672 				qd_idx = 0;
2673 			} else if (*dd_idx >= pd_idx)
2674 				(*dd_idx) += 2; /* D D P Q D */
2675 			ddf_layout = 1;
2676 			break;
2677 
2678 		case ALGORITHM_ROTATING_N_CONTINUE:
2679 			/* Same as left_symmetric but Q is before P */
2680 			pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2681 			qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2682 			*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2683 			ddf_layout = 1;
2684 			break;
2685 
2686 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2687 			/* RAID5 left_asymmetric, with Q on last device */
2688 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2689 			if (*dd_idx >= pd_idx)
2690 				(*dd_idx)++;
2691 			qd_idx = raid_disks - 1;
2692 			break;
2693 
2694 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2695 			pd_idx = sector_div(stripe2, raid_disks-1);
2696 			if (*dd_idx >= pd_idx)
2697 				(*dd_idx)++;
2698 			qd_idx = raid_disks - 1;
2699 			break;
2700 
2701 		case ALGORITHM_LEFT_SYMMETRIC_6:
2702 			pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2703 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2704 			qd_idx = raid_disks - 1;
2705 			break;
2706 
2707 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2708 			pd_idx = sector_div(stripe2, raid_disks-1);
2709 			*dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2710 			qd_idx = raid_disks - 1;
2711 			break;
2712 
2713 		case ALGORITHM_PARITY_0_6:
2714 			pd_idx = 0;
2715 			(*dd_idx)++;
2716 			qd_idx = raid_disks - 1;
2717 			break;
2718 
2719 		default:
2720 			BUG();
2721 		}
2722 		break;
2723 	}
2724 
2725 	if (sh) {
2726 		sh->pd_idx = pd_idx;
2727 		sh->qd_idx = qd_idx;
2728 		sh->ddf_layout = ddf_layout;
2729 	}
2730 	/*
2731 	 * Finally, compute the new sector number
2732 	 */
2733 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2734 	return new_sector;
2735 }
2736 
2737 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2738 {
2739 	struct r5conf *conf = sh->raid_conf;
2740 	int raid_disks = sh->disks;
2741 	int data_disks = raid_disks - conf->max_degraded;
2742 	sector_t new_sector = sh->sector, check;
2743 	int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2744 					 : conf->chunk_sectors;
2745 	int algorithm = previous ? conf->prev_algo
2746 				 : conf->algorithm;
2747 	sector_t stripe;
2748 	int chunk_offset;
2749 	sector_t chunk_number;
2750 	int dummy1, dd_idx = i;
2751 	sector_t r_sector;
2752 	struct stripe_head sh2;
2753 
2754 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
2755 	stripe = new_sector;
2756 
2757 	if (i == sh->pd_idx)
2758 		return 0;
2759 	switch(conf->level) {
2760 	case 4: break;
2761 	case 5:
2762 		switch (algorithm) {
2763 		case ALGORITHM_LEFT_ASYMMETRIC:
2764 		case ALGORITHM_RIGHT_ASYMMETRIC:
2765 			if (i > sh->pd_idx)
2766 				i--;
2767 			break;
2768 		case ALGORITHM_LEFT_SYMMETRIC:
2769 		case ALGORITHM_RIGHT_SYMMETRIC:
2770 			if (i < sh->pd_idx)
2771 				i += raid_disks;
2772 			i -= (sh->pd_idx + 1);
2773 			break;
2774 		case ALGORITHM_PARITY_0:
2775 			i -= 1;
2776 			break;
2777 		case ALGORITHM_PARITY_N:
2778 			break;
2779 		default:
2780 			BUG();
2781 		}
2782 		break;
2783 	case 6:
2784 		if (i == sh->qd_idx)
2785 			return 0; /* It is the Q disk */
2786 		switch (algorithm) {
2787 		case ALGORITHM_LEFT_ASYMMETRIC:
2788 		case ALGORITHM_RIGHT_ASYMMETRIC:
2789 		case ALGORITHM_ROTATING_ZERO_RESTART:
2790 		case ALGORITHM_ROTATING_N_RESTART:
2791 			if (sh->pd_idx == raid_disks-1)
2792 				i--;	/* Q D D D P */
2793 			else if (i > sh->pd_idx)
2794 				i -= 2; /* D D P Q D */
2795 			break;
2796 		case ALGORITHM_LEFT_SYMMETRIC:
2797 		case ALGORITHM_RIGHT_SYMMETRIC:
2798 			if (sh->pd_idx == raid_disks-1)
2799 				i--; /* Q D D D P */
2800 			else {
2801 				/* D D P Q D */
2802 				if (i < sh->pd_idx)
2803 					i += raid_disks;
2804 				i -= (sh->pd_idx + 2);
2805 			}
2806 			break;
2807 		case ALGORITHM_PARITY_0:
2808 			i -= 2;
2809 			break;
2810 		case ALGORITHM_PARITY_N:
2811 			break;
2812 		case ALGORITHM_ROTATING_N_CONTINUE:
2813 			/* Like left_symmetric, but P is before Q */
2814 			if (sh->pd_idx == 0)
2815 				i--;	/* P D D D Q */
2816 			else {
2817 				/* D D Q P D */
2818 				if (i < sh->pd_idx)
2819 					i += raid_disks;
2820 				i -= (sh->pd_idx + 1);
2821 			}
2822 			break;
2823 		case ALGORITHM_LEFT_ASYMMETRIC_6:
2824 		case ALGORITHM_RIGHT_ASYMMETRIC_6:
2825 			if (i > sh->pd_idx)
2826 				i--;
2827 			break;
2828 		case ALGORITHM_LEFT_SYMMETRIC_6:
2829 		case ALGORITHM_RIGHT_SYMMETRIC_6:
2830 			if (i < sh->pd_idx)
2831 				i += data_disks + 1;
2832 			i -= (sh->pd_idx + 1);
2833 			break;
2834 		case ALGORITHM_PARITY_0_6:
2835 			i -= 1;
2836 			break;
2837 		default:
2838 			BUG();
2839 		}
2840 		break;
2841 	}
2842 
2843 	chunk_number = stripe * data_disks + i;
2844 	r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2845 
2846 	check = raid5_compute_sector(conf, r_sector,
2847 				     previous, &dummy1, &sh2);
2848 	if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2849 		|| sh2.qd_idx != sh->qd_idx) {
2850 		printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2851 		       mdname(conf->mddev));
2852 		return 0;
2853 	}
2854 	return r_sector;
2855 }
2856 
2857 static void
2858 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2859 			 int rcw, int expand)
2860 {
2861 	int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
2862 	struct r5conf *conf = sh->raid_conf;
2863 	int level = conf->level;
2864 
2865 	if (rcw) {
2866 
2867 		for (i = disks; i--; ) {
2868 			struct r5dev *dev = &sh->dev[i];
2869 
2870 			if (dev->towrite) {
2871 				set_bit(R5_LOCKED, &dev->flags);
2872 				set_bit(R5_Wantdrain, &dev->flags);
2873 				if (!expand)
2874 					clear_bit(R5_UPTODATE, &dev->flags);
2875 				s->locked++;
2876 			}
2877 		}
2878 		/* if we are not expanding this is a proper write request, and
2879 		 * there will be bios with new data to be drained into the
2880 		 * stripe cache
2881 		 */
2882 		if (!expand) {
2883 			if (!s->locked)
2884 				/* False alarm, nothing to do */
2885 				return;
2886 			sh->reconstruct_state = reconstruct_state_drain_run;
2887 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2888 		} else
2889 			sh->reconstruct_state = reconstruct_state_run;
2890 
2891 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2892 
2893 		if (s->locked + conf->max_degraded == disks)
2894 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2895 				atomic_inc(&conf->pending_full_writes);
2896 	} else {
2897 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2898 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2899 		BUG_ON(level == 6 &&
2900 			(!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
2901 			   test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
2902 
2903 		for (i = disks; i--; ) {
2904 			struct r5dev *dev = &sh->dev[i];
2905 			if (i == pd_idx || i == qd_idx)
2906 				continue;
2907 
2908 			if (dev->towrite &&
2909 			    (test_bit(R5_UPTODATE, &dev->flags) ||
2910 			     test_bit(R5_Wantcompute, &dev->flags))) {
2911 				set_bit(R5_Wantdrain, &dev->flags);
2912 				set_bit(R5_LOCKED, &dev->flags);
2913 				clear_bit(R5_UPTODATE, &dev->flags);
2914 				s->locked++;
2915 			}
2916 		}
2917 		if (!s->locked)
2918 			/* False alarm - nothing to do */
2919 			return;
2920 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2921 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2922 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2923 		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2924 	}
2925 
2926 	/* keep the parity disk(s) locked while asynchronous operations
2927 	 * are in flight
2928 	 */
2929 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2930 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2931 	s->locked++;
2932 
2933 	if (level == 6) {
2934 		int qd_idx = sh->qd_idx;
2935 		struct r5dev *dev = &sh->dev[qd_idx];
2936 
2937 		set_bit(R5_LOCKED, &dev->flags);
2938 		clear_bit(R5_UPTODATE, &dev->flags);
2939 		s->locked++;
2940 	}
2941 
2942 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2943 		__func__, (unsigned long long)sh->sector,
2944 		s->locked, s->ops_request);
2945 }
2946 
2947 /*
2948  * Each stripe/dev can have one or more bion attached.
2949  * toread/towrite point to the first in a chain.
2950  * The bi_next chain must be in order.
2951  */
2952 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
2953 			  int forwrite, int previous)
2954 {
2955 	struct bio **bip;
2956 	struct r5conf *conf = sh->raid_conf;
2957 	int firstwrite=0;
2958 
2959 	pr_debug("adding bi b#%llu to stripe s#%llu\n",
2960 		(unsigned long long)bi->bi_iter.bi_sector,
2961 		(unsigned long long)sh->sector);
2962 
2963 	/*
2964 	 * If several bio share a stripe. The bio bi_phys_segments acts as a
2965 	 * reference count to avoid race. The reference count should already be
2966 	 * increased before this function is called (for example, in
2967 	 * make_request()), so other bio sharing this stripe will not free the
2968 	 * stripe. If a stripe is owned by one stripe, the stripe lock will
2969 	 * protect it.
2970 	 */
2971 	spin_lock_irq(&sh->stripe_lock);
2972 	/* Don't allow new IO added to stripes in batch list */
2973 	if (sh->batch_head)
2974 		goto overlap;
2975 	if (forwrite) {
2976 		bip = &sh->dev[dd_idx].towrite;
2977 		if (*bip == NULL)
2978 			firstwrite = 1;
2979 	} else
2980 		bip = &sh->dev[dd_idx].toread;
2981 	while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
2982 		if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
2983 			goto overlap;
2984 		bip = & (*bip)->bi_next;
2985 	}
2986 	if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
2987 		goto overlap;
2988 
2989 	if (!forwrite || previous)
2990 		clear_bit(STRIPE_BATCH_READY, &sh->state);
2991 
2992 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2993 	if (*bip)
2994 		bi->bi_next = *bip;
2995 	*bip = bi;
2996 	raid5_inc_bi_active_stripes(bi);
2997 
2998 	if (forwrite) {
2999 		/* check if page is covered */
3000 		sector_t sector = sh->dev[dd_idx].sector;
3001 		for (bi=sh->dev[dd_idx].towrite;
3002 		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
3003 			     bi && bi->bi_iter.bi_sector <= sector;
3004 		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
3005 			if (bio_end_sector(bi) >= sector)
3006 				sector = bio_end_sector(bi);
3007 		}
3008 		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
3009 			if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3010 				sh->overwrite_disks++;
3011 	}
3012 
3013 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3014 		(unsigned long long)(*bip)->bi_iter.bi_sector,
3015 		(unsigned long long)sh->sector, dd_idx);
3016 
3017 	if (conf->mddev->bitmap && firstwrite) {
3018 		/* Cannot hold spinlock over bitmap_startwrite,
3019 		 * but must ensure this isn't added to a batch until
3020 		 * we have added to the bitmap and set bm_seq.
3021 		 * So set STRIPE_BITMAP_PENDING to prevent
3022 		 * batching.
3023 		 * If multiple add_stripe_bio() calls race here they
3024 		 * much all set STRIPE_BITMAP_PENDING.  So only the first one
3025 		 * to complete "bitmap_startwrite" gets to set
3026 		 * STRIPE_BIT_DELAY.  This is important as once a stripe
3027 		 * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3028 		 * any more.
3029 		 */
3030 		set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3031 		spin_unlock_irq(&sh->stripe_lock);
3032 		bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3033 				  STRIPE_SECTORS, 0);
3034 		spin_lock_irq(&sh->stripe_lock);
3035 		clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3036 		if (!sh->batch_head) {
3037 			sh->bm_seq = conf->seq_flush+1;
3038 			set_bit(STRIPE_BIT_DELAY, &sh->state);
3039 		}
3040 	}
3041 	spin_unlock_irq(&sh->stripe_lock);
3042 
3043 	if (stripe_can_batch(sh))
3044 		stripe_add_to_batch_list(conf, sh);
3045 	return 1;
3046 
3047  overlap:
3048 	set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3049 	spin_unlock_irq(&sh->stripe_lock);
3050 	return 0;
3051 }
3052 
3053 static void end_reshape(struct r5conf *conf);
3054 
3055 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3056 			    struct stripe_head *sh)
3057 {
3058 	int sectors_per_chunk =
3059 		previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3060 	int dd_idx;
3061 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
3062 	int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3063 
3064 	raid5_compute_sector(conf,
3065 			     stripe * (disks - conf->max_degraded)
3066 			     *sectors_per_chunk + chunk_offset,
3067 			     previous,
3068 			     &dd_idx, sh);
3069 }
3070 
3071 static void
3072 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3073 				struct stripe_head_state *s, int disks,
3074 				struct bio **return_bi)
3075 {
3076 	int i;
3077 	BUG_ON(sh->batch_head);
3078 	for (i = disks; i--; ) {
3079 		struct bio *bi;
3080 		int bitmap_end = 0;
3081 
3082 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3083 			struct md_rdev *rdev;
3084 			rcu_read_lock();
3085 			rdev = rcu_dereference(conf->disks[i].rdev);
3086 			if (rdev && test_bit(In_sync, &rdev->flags))
3087 				atomic_inc(&rdev->nr_pending);
3088 			else
3089 				rdev = NULL;
3090 			rcu_read_unlock();
3091 			if (rdev) {
3092 				if (!rdev_set_badblocks(
3093 					    rdev,
3094 					    sh->sector,
3095 					    STRIPE_SECTORS, 0))
3096 					md_error(conf->mddev, rdev);
3097 				rdev_dec_pending(rdev, conf->mddev);
3098 			}
3099 		}
3100 		spin_lock_irq(&sh->stripe_lock);
3101 		/* fail all writes first */
3102 		bi = sh->dev[i].towrite;
3103 		sh->dev[i].towrite = NULL;
3104 		sh->overwrite_disks = 0;
3105 		spin_unlock_irq(&sh->stripe_lock);
3106 		if (bi)
3107 			bitmap_end = 1;
3108 
3109 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3110 			wake_up(&conf->wait_for_overlap);
3111 
3112 		while (bi && bi->bi_iter.bi_sector <
3113 			sh->dev[i].sector + STRIPE_SECTORS) {
3114 			struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3115 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
3116 			if (!raid5_dec_bi_active_stripes(bi)) {
3117 				md_write_end(conf->mddev);
3118 				bi->bi_next = *return_bi;
3119 				*return_bi = bi;
3120 			}
3121 			bi = nextbi;
3122 		}
3123 		if (bitmap_end)
3124 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3125 				STRIPE_SECTORS, 0, 0);
3126 		bitmap_end = 0;
3127 		/* and fail all 'written' */
3128 		bi = sh->dev[i].written;
3129 		sh->dev[i].written = NULL;
3130 		if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3131 			WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3132 			sh->dev[i].page = sh->dev[i].orig_page;
3133 		}
3134 
3135 		if (bi) bitmap_end = 1;
3136 		while (bi && bi->bi_iter.bi_sector <
3137 		       sh->dev[i].sector + STRIPE_SECTORS) {
3138 			struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3139 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
3140 			if (!raid5_dec_bi_active_stripes(bi)) {
3141 				md_write_end(conf->mddev);
3142 				bi->bi_next = *return_bi;
3143 				*return_bi = bi;
3144 			}
3145 			bi = bi2;
3146 		}
3147 
3148 		/* fail any reads if this device is non-operational and
3149 		 * the data has not reached the cache yet.
3150 		 */
3151 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3152 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3153 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
3154 			spin_lock_irq(&sh->stripe_lock);
3155 			bi = sh->dev[i].toread;
3156 			sh->dev[i].toread = NULL;
3157 			spin_unlock_irq(&sh->stripe_lock);
3158 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3159 				wake_up(&conf->wait_for_overlap);
3160 			while (bi && bi->bi_iter.bi_sector <
3161 			       sh->dev[i].sector + STRIPE_SECTORS) {
3162 				struct bio *nextbi =
3163 					r5_next_bio(bi, sh->dev[i].sector);
3164 				clear_bit(BIO_UPTODATE, &bi->bi_flags);
3165 				if (!raid5_dec_bi_active_stripes(bi)) {
3166 					bi->bi_next = *return_bi;
3167 					*return_bi = bi;
3168 				}
3169 				bi = nextbi;
3170 			}
3171 		}
3172 		if (bitmap_end)
3173 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3174 					STRIPE_SECTORS, 0, 0);
3175 		/* If we were in the middle of a write the parity block might
3176 		 * still be locked - so just clear all R5_LOCKED flags
3177 		 */
3178 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
3179 	}
3180 
3181 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3182 		if (atomic_dec_and_test(&conf->pending_full_writes))
3183 			md_wakeup_thread(conf->mddev->thread);
3184 }
3185 
3186 static void
3187 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3188 		   struct stripe_head_state *s)
3189 {
3190 	int abort = 0;
3191 	int i;
3192 
3193 	BUG_ON(sh->batch_head);
3194 	clear_bit(STRIPE_SYNCING, &sh->state);
3195 	if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3196 		wake_up(&conf->wait_for_overlap);
3197 	s->syncing = 0;
3198 	s->replacing = 0;
3199 	/* There is nothing more to do for sync/check/repair.
3200 	 * Don't even need to abort as that is handled elsewhere
3201 	 * if needed, and not always wanted e.g. if there is a known
3202 	 * bad block here.
3203 	 * For recover/replace we need to record a bad block on all
3204 	 * non-sync devices, or abort the recovery
3205 	 */
3206 	if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3207 		/* During recovery devices cannot be removed, so
3208 		 * locking and refcounting of rdevs is not needed
3209 		 */
3210 		for (i = 0; i < conf->raid_disks; i++) {
3211 			struct md_rdev *rdev = conf->disks[i].rdev;
3212 			if (rdev
3213 			    && !test_bit(Faulty, &rdev->flags)
3214 			    && !test_bit(In_sync, &rdev->flags)
3215 			    && !rdev_set_badblocks(rdev, sh->sector,
3216 						   STRIPE_SECTORS, 0))
3217 				abort = 1;
3218 			rdev = conf->disks[i].replacement;
3219 			if (rdev
3220 			    && !test_bit(Faulty, &rdev->flags)
3221 			    && !test_bit(In_sync, &rdev->flags)
3222 			    && !rdev_set_badblocks(rdev, sh->sector,
3223 						   STRIPE_SECTORS, 0))
3224 				abort = 1;
3225 		}
3226 		if (abort)
3227 			conf->recovery_disabled =
3228 				conf->mddev->recovery_disabled;
3229 	}
3230 	md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3231 }
3232 
3233 static int want_replace(struct stripe_head *sh, int disk_idx)
3234 {
3235 	struct md_rdev *rdev;
3236 	int rv = 0;
3237 	/* Doing recovery so rcu locking not required */
3238 	rdev = sh->raid_conf->disks[disk_idx].replacement;
3239 	if (rdev
3240 	    && !test_bit(Faulty, &rdev->flags)
3241 	    && !test_bit(In_sync, &rdev->flags)
3242 	    && (rdev->recovery_offset <= sh->sector
3243 		|| rdev->mddev->recovery_cp <= sh->sector))
3244 		rv = 1;
3245 
3246 	return rv;
3247 }
3248 
3249 /* fetch_block - checks the given member device to see if its data needs
3250  * to be read or computed to satisfy a request.
3251  *
3252  * Returns 1 when no more member devices need to be checked, otherwise returns
3253  * 0 to tell the loop in handle_stripe_fill to continue
3254  */
3255 
3256 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3257 			   int disk_idx, int disks)
3258 {
3259 	struct r5dev *dev = &sh->dev[disk_idx];
3260 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3261 				  &sh->dev[s->failed_num[1]] };
3262 	int i;
3263 
3264 
3265 	if (test_bit(R5_LOCKED, &dev->flags) ||
3266 	    test_bit(R5_UPTODATE, &dev->flags))
3267 		/* No point reading this as we already have it or have
3268 		 * decided to get it.
3269 		 */
3270 		return 0;
3271 
3272 	if (dev->toread ||
3273 	    (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3274 		/* We need this block to directly satisfy a request */
3275 		return 1;
3276 
3277 	if (s->syncing || s->expanding ||
3278 	    (s->replacing && want_replace(sh, disk_idx)))
3279 		/* When syncing, or expanding we read everything.
3280 		 * When replacing, we need the replaced block.
3281 		 */
3282 		return 1;
3283 
3284 	if ((s->failed >= 1 && fdev[0]->toread) ||
3285 	    (s->failed >= 2 && fdev[1]->toread))
3286 		/* If we want to read from a failed device, then
3287 		 * we need to actually read every other device.
3288 		 */
3289 		return 1;
3290 
3291 	/* Sometimes neither read-modify-write nor reconstruct-write
3292 	 * cycles can work.  In those cases we read every block we
3293 	 * can.  Then the parity-update is certain to have enough to
3294 	 * work with.
3295 	 * This can only be a problem when we need to write something,
3296 	 * and some device has failed.  If either of those tests
3297 	 * fail we need look no further.
3298 	 */
3299 	if (!s->failed || !s->to_write)
3300 		return 0;
3301 
3302 	if (test_bit(R5_Insync, &dev->flags) &&
3303 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3304 		/* Pre-reads at not permitted until after short delay
3305 		 * to gather multiple requests.  However if this
3306 		 * device is no Insync, the block could only be be computed
3307 		 * and there is no need to delay that.
3308 		 */
3309 		return 0;
3310 
3311 	for (i = 0; i < s->failed; i++) {
3312 		if (fdev[i]->towrite &&
3313 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3314 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3315 			/* If we have a partial write to a failed
3316 			 * device, then we will need to reconstruct
3317 			 * the content of that device, so all other
3318 			 * devices must be read.
3319 			 */
3320 			return 1;
3321 	}
3322 
3323 	/* If we are forced to do a reconstruct-write, either because
3324 	 * the current RAID6 implementation only supports that, or
3325 	 * or because parity cannot be trusted and we are currently
3326 	 * recovering it, there is extra need to be careful.
3327 	 * If one of the devices that we would need to read, because
3328 	 * it is not being overwritten (and maybe not written at all)
3329 	 * is missing/faulty, then we need to read everything we can.
3330 	 */
3331 	if (sh->raid_conf->level != 6 &&
3332 	    sh->sector < sh->raid_conf->mddev->recovery_cp)
3333 		/* reconstruct-write isn't being forced */
3334 		return 0;
3335 	for (i = 0; i < s->failed; i++) {
3336 		if (s->failed_num[i] != sh->pd_idx &&
3337 		    s->failed_num[i] != sh->qd_idx &&
3338 		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3339 		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3340 			return 1;
3341 	}
3342 
3343 	return 0;
3344 }
3345 
3346 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3347 		       int disk_idx, int disks)
3348 {
3349 	struct r5dev *dev = &sh->dev[disk_idx];
3350 
3351 	/* is the data in this block needed, and can we get it? */
3352 	if (need_this_block(sh, s, disk_idx, disks)) {
3353 		/* we would like to get this block, possibly by computing it,
3354 		 * otherwise read it if the backing disk is insync
3355 		 */
3356 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3357 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
3358 		BUG_ON(sh->batch_head);
3359 		if ((s->uptodate == disks - 1) &&
3360 		    (s->failed && (disk_idx == s->failed_num[0] ||
3361 				   disk_idx == s->failed_num[1]))) {
3362 			/* have disk failed, and we're requested to fetch it;
3363 			 * do compute it
3364 			 */
3365 			pr_debug("Computing stripe %llu block %d\n",
3366 			       (unsigned long long)sh->sector, disk_idx);
3367 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3368 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3369 			set_bit(R5_Wantcompute, &dev->flags);
3370 			sh->ops.target = disk_idx;
3371 			sh->ops.target2 = -1; /* no 2nd target */
3372 			s->req_compute = 1;
3373 			/* Careful: from this point on 'uptodate' is in the eye
3374 			 * of raid_run_ops which services 'compute' operations
3375 			 * before writes. R5_Wantcompute flags a block that will
3376 			 * be R5_UPTODATE by the time it is needed for a
3377 			 * subsequent operation.
3378 			 */
3379 			s->uptodate++;
3380 			return 1;
3381 		} else if (s->uptodate == disks-2 && s->failed >= 2) {
3382 			/* Computing 2-failure is *very* expensive; only
3383 			 * do it if failed >= 2
3384 			 */
3385 			int other;
3386 			for (other = disks; other--; ) {
3387 				if (other == disk_idx)
3388 					continue;
3389 				if (!test_bit(R5_UPTODATE,
3390 				      &sh->dev[other].flags))
3391 					break;
3392 			}
3393 			BUG_ON(other < 0);
3394 			pr_debug("Computing stripe %llu blocks %d,%d\n",
3395 			       (unsigned long long)sh->sector,
3396 			       disk_idx, other);
3397 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3398 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3399 			set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3400 			set_bit(R5_Wantcompute, &sh->dev[other].flags);
3401 			sh->ops.target = disk_idx;
3402 			sh->ops.target2 = other;
3403 			s->uptodate += 2;
3404 			s->req_compute = 1;
3405 			return 1;
3406 		} else if (test_bit(R5_Insync, &dev->flags)) {
3407 			set_bit(R5_LOCKED, &dev->flags);
3408 			set_bit(R5_Wantread, &dev->flags);
3409 			s->locked++;
3410 			pr_debug("Reading block %d (sync=%d)\n",
3411 				disk_idx, s->syncing);
3412 		}
3413 	}
3414 
3415 	return 0;
3416 }
3417 
3418 /**
3419  * handle_stripe_fill - read or compute data to satisfy pending requests.
3420  */
3421 static void handle_stripe_fill(struct stripe_head *sh,
3422 			       struct stripe_head_state *s,
3423 			       int disks)
3424 {
3425 	int i;
3426 
3427 	/* look for blocks to read/compute, skip this if a compute
3428 	 * is already in flight, or if the stripe contents are in the
3429 	 * midst of changing due to a write
3430 	 */
3431 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3432 	    !sh->reconstruct_state)
3433 		for (i = disks; i--; )
3434 			if (fetch_block(sh, s, i, disks))
3435 				break;
3436 	set_bit(STRIPE_HANDLE, &sh->state);
3437 }
3438 
3439 static void break_stripe_batch_list(struct stripe_head *head_sh,
3440 				    unsigned long handle_flags);
3441 /* handle_stripe_clean_event
3442  * any written block on an uptodate or failed drive can be returned.
3443  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3444  * never LOCKED, so we don't need to test 'failed' directly.
3445  */
3446 static void handle_stripe_clean_event(struct r5conf *conf,
3447 	struct stripe_head *sh, int disks, struct bio **return_bi)
3448 {
3449 	int i;
3450 	struct r5dev *dev;
3451 	int discard_pending = 0;
3452 	struct stripe_head *head_sh = sh;
3453 	bool do_endio = false;
3454 
3455 	for (i = disks; i--; )
3456 		if (sh->dev[i].written) {
3457 			dev = &sh->dev[i];
3458 			if (!test_bit(R5_LOCKED, &dev->flags) &&
3459 			    (test_bit(R5_UPTODATE, &dev->flags) ||
3460 			     test_bit(R5_Discard, &dev->flags) ||
3461 			     test_bit(R5_SkipCopy, &dev->flags))) {
3462 				/* We can return any write requests */
3463 				struct bio *wbi, *wbi2;
3464 				pr_debug("Return write for disc %d\n", i);
3465 				if (test_and_clear_bit(R5_Discard, &dev->flags))
3466 					clear_bit(R5_UPTODATE, &dev->flags);
3467 				if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3468 					WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3469 				}
3470 				do_endio = true;
3471 
3472 returnbi:
3473 				dev->page = dev->orig_page;
3474 				wbi = dev->written;
3475 				dev->written = NULL;
3476 				while (wbi && wbi->bi_iter.bi_sector <
3477 					dev->sector + STRIPE_SECTORS) {
3478 					wbi2 = r5_next_bio(wbi, dev->sector);
3479 					if (!raid5_dec_bi_active_stripes(wbi)) {
3480 						md_write_end(conf->mddev);
3481 						wbi->bi_next = *return_bi;
3482 						*return_bi = wbi;
3483 					}
3484 					wbi = wbi2;
3485 				}
3486 				bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3487 						STRIPE_SECTORS,
3488 					 !test_bit(STRIPE_DEGRADED, &sh->state),
3489 						0);
3490 				if (head_sh->batch_head) {
3491 					sh = list_first_entry(&sh->batch_list,
3492 							      struct stripe_head,
3493 							      batch_list);
3494 					if (sh != head_sh) {
3495 						dev = &sh->dev[i];
3496 						goto returnbi;
3497 					}
3498 				}
3499 				sh = head_sh;
3500 				dev = &sh->dev[i];
3501 			} else if (test_bit(R5_Discard, &dev->flags))
3502 				discard_pending = 1;
3503 			WARN_ON(test_bit(R5_SkipCopy, &dev->flags));
3504 			WARN_ON(dev->page != dev->orig_page);
3505 		}
3506 	if (!discard_pending &&
3507 	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3508 		clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3509 		clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3510 		if (sh->qd_idx >= 0) {
3511 			clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3512 			clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3513 		}
3514 		/* now that discard is done we can proceed with any sync */
3515 		clear_bit(STRIPE_DISCARD, &sh->state);
3516 		/*
3517 		 * SCSI discard will change some bio fields and the stripe has
3518 		 * no updated data, so remove it from hash list and the stripe
3519 		 * will be reinitialized
3520 		 */
3521 		spin_lock_irq(&conf->device_lock);
3522 unhash:
3523 		remove_hash(sh);
3524 		if (head_sh->batch_head) {
3525 			sh = list_first_entry(&sh->batch_list,
3526 					      struct stripe_head, batch_list);
3527 			if (sh != head_sh)
3528 					goto unhash;
3529 		}
3530 		spin_unlock_irq(&conf->device_lock);
3531 		sh = head_sh;
3532 
3533 		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3534 			set_bit(STRIPE_HANDLE, &sh->state);
3535 
3536 	}
3537 
3538 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3539 		if (atomic_dec_and_test(&conf->pending_full_writes))
3540 			md_wakeup_thread(conf->mddev->thread);
3541 
3542 	if (head_sh->batch_head && do_endio)
3543 		break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3544 }
3545 
3546 static void handle_stripe_dirtying(struct r5conf *conf,
3547 				   struct stripe_head *sh,
3548 				   struct stripe_head_state *s,
3549 				   int disks)
3550 {
3551 	int rmw = 0, rcw = 0, i;
3552 	sector_t recovery_cp = conf->mddev->recovery_cp;
3553 
3554 	/* Check whether resync is now happening or should start.
3555 	 * If yes, then the array is dirty (after unclean shutdown or
3556 	 * initial creation), so parity in some stripes might be inconsistent.
3557 	 * In this case, we need to always do reconstruct-write, to ensure
3558 	 * that in case of drive failure or read-error correction, we
3559 	 * generate correct data from the parity.
3560 	 */
3561 	if (conf->rmw_level == PARITY_DISABLE_RMW ||
3562 	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3563 	     s->failed == 0)) {
3564 		/* Calculate the real rcw later - for now make it
3565 		 * look like rcw is cheaper
3566 		 */
3567 		rcw = 1; rmw = 2;
3568 		pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3569 			 conf->rmw_level, (unsigned long long)recovery_cp,
3570 			 (unsigned long long)sh->sector);
3571 	} else for (i = disks; i--; ) {
3572 		/* would I have to read this buffer for read_modify_write */
3573 		struct r5dev *dev = &sh->dev[i];
3574 		if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx) &&
3575 		    !test_bit(R5_LOCKED, &dev->flags) &&
3576 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
3577 		      test_bit(R5_Wantcompute, &dev->flags))) {
3578 			if (test_bit(R5_Insync, &dev->flags))
3579 				rmw++;
3580 			else
3581 				rmw += 2*disks;  /* cannot read it */
3582 		}
3583 		/* Would I have to read this buffer for reconstruct_write */
3584 		if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3585 		    i != sh->pd_idx && i != sh->qd_idx &&
3586 		    !test_bit(R5_LOCKED, &dev->flags) &&
3587 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
3588 		    test_bit(R5_Wantcompute, &dev->flags))) {
3589 			if (test_bit(R5_Insync, &dev->flags))
3590 				rcw++;
3591 			else
3592 				rcw += 2*disks;
3593 		}
3594 	}
3595 	pr_debug("for sector %llu, rmw=%d rcw=%d\n",
3596 		(unsigned long long)sh->sector, rmw, rcw);
3597 	set_bit(STRIPE_HANDLE, &sh->state);
3598 	if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_ENABLE_RMW)) && rmw > 0) {
3599 		/* prefer read-modify-write, but need to get some data */
3600 		if (conf->mddev->queue)
3601 			blk_add_trace_msg(conf->mddev->queue,
3602 					  "raid5 rmw %llu %d",
3603 					  (unsigned long long)sh->sector, rmw);
3604 		for (i = disks; i--; ) {
3605 			struct r5dev *dev = &sh->dev[i];
3606 			if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx) &&
3607 			    !test_bit(R5_LOCKED, &dev->flags) &&
3608 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
3609 			    test_bit(R5_Wantcompute, &dev->flags)) &&
3610 			    test_bit(R5_Insync, &dev->flags)) {
3611 				if (test_bit(STRIPE_PREREAD_ACTIVE,
3612 					     &sh->state)) {
3613 					pr_debug("Read_old block %d for r-m-w\n",
3614 						 i);
3615 					set_bit(R5_LOCKED, &dev->flags);
3616 					set_bit(R5_Wantread, &dev->flags);
3617 					s->locked++;
3618 				} else {
3619 					set_bit(STRIPE_DELAYED, &sh->state);
3620 					set_bit(STRIPE_HANDLE, &sh->state);
3621 				}
3622 			}
3623 		}
3624 	}
3625 	if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_ENABLE_RMW)) && rcw > 0) {
3626 		/* want reconstruct write, but need to get some data */
3627 		int qread =0;
3628 		rcw = 0;
3629 		for (i = disks; i--; ) {
3630 			struct r5dev *dev = &sh->dev[i];
3631 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3632 			    i != sh->pd_idx && i != sh->qd_idx &&
3633 			    !test_bit(R5_LOCKED, &dev->flags) &&
3634 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
3635 			      test_bit(R5_Wantcompute, &dev->flags))) {
3636 				rcw++;
3637 				if (test_bit(R5_Insync, &dev->flags) &&
3638 				    test_bit(STRIPE_PREREAD_ACTIVE,
3639 					     &sh->state)) {
3640 					pr_debug("Read_old block "
3641 						"%d for Reconstruct\n", i);
3642 					set_bit(R5_LOCKED, &dev->flags);
3643 					set_bit(R5_Wantread, &dev->flags);
3644 					s->locked++;
3645 					qread++;
3646 				} else {
3647 					set_bit(STRIPE_DELAYED, &sh->state);
3648 					set_bit(STRIPE_HANDLE, &sh->state);
3649 				}
3650 			}
3651 		}
3652 		if (rcw && conf->mddev->queue)
3653 			blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3654 					  (unsigned long long)sh->sector,
3655 					  rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3656 	}
3657 
3658 	if (rcw > disks && rmw > disks &&
3659 	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3660 		set_bit(STRIPE_DELAYED, &sh->state);
3661 
3662 	/* now if nothing is locked, and if we have enough data,
3663 	 * we can start a write request
3664 	 */
3665 	/* since handle_stripe can be called at any time we need to handle the
3666 	 * case where a compute block operation has been submitted and then a
3667 	 * subsequent call wants to start a write request.  raid_run_ops only
3668 	 * handles the case where compute block and reconstruct are requested
3669 	 * simultaneously.  If this is not the case then new writes need to be
3670 	 * held off until the compute completes.
3671 	 */
3672 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3673 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3674 	    !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3675 		schedule_reconstruction(sh, s, rcw == 0, 0);
3676 }
3677 
3678 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3679 				struct stripe_head_state *s, int disks)
3680 {
3681 	struct r5dev *dev = NULL;
3682 
3683 	BUG_ON(sh->batch_head);
3684 	set_bit(STRIPE_HANDLE, &sh->state);
3685 
3686 	switch (sh->check_state) {
3687 	case check_state_idle:
3688 		/* start a new check operation if there are no failures */
3689 		if (s->failed == 0) {
3690 			BUG_ON(s->uptodate != disks);
3691 			sh->check_state = check_state_run;
3692 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3693 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3694 			s->uptodate--;
3695 			break;
3696 		}
3697 		dev = &sh->dev[s->failed_num[0]];
3698 		/* fall through */
3699 	case check_state_compute_result:
3700 		sh->check_state = check_state_idle;
3701 		if (!dev)
3702 			dev = &sh->dev[sh->pd_idx];
3703 
3704 		/* check that a write has not made the stripe insync */
3705 		if (test_bit(STRIPE_INSYNC, &sh->state))
3706 			break;
3707 
3708 		/* either failed parity check, or recovery is happening */
3709 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3710 		BUG_ON(s->uptodate != disks);
3711 
3712 		set_bit(R5_LOCKED, &dev->flags);
3713 		s->locked++;
3714 		set_bit(R5_Wantwrite, &dev->flags);
3715 
3716 		clear_bit(STRIPE_DEGRADED, &sh->state);
3717 		set_bit(STRIPE_INSYNC, &sh->state);
3718 		break;
3719 	case check_state_run:
3720 		break; /* we will be called again upon completion */
3721 	case check_state_check_result:
3722 		sh->check_state = check_state_idle;
3723 
3724 		/* if a failure occurred during the check operation, leave
3725 		 * STRIPE_INSYNC not set and let the stripe be handled again
3726 		 */
3727 		if (s->failed)
3728 			break;
3729 
3730 		/* handle a successful check operation, if parity is correct
3731 		 * we are done.  Otherwise update the mismatch count and repair
3732 		 * parity if !MD_RECOVERY_CHECK
3733 		 */
3734 		if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3735 			/* parity is correct (on disc,
3736 			 * not in buffer any more)
3737 			 */
3738 			set_bit(STRIPE_INSYNC, &sh->state);
3739 		else {
3740 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3741 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3742 				/* don't try to repair!! */
3743 				set_bit(STRIPE_INSYNC, &sh->state);
3744 			else {
3745 				sh->check_state = check_state_compute_run;
3746 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3747 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3748 				set_bit(R5_Wantcompute,
3749 					&sh->dev[sh->pd_idx].flags);
3750 				sh->ops.target = sh->pd_idx;
3751 				sh->ops.target2 = -1;
3752 				s->uptodate++;
3753 			}
3754 		}
3755 		break;
3756 	case check_state_compute_run:
3757 		break;
3758 	default:
3759 		printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3760 		       __func__, sh->check_state,
3761 		       (unsigned long long) sh->sector);
3762 		BUG();
3763 	}
3764 }
3765 
3766 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3767 				  struct stripe_head_state *s,
3768 				  int disks)
3769 {
3770 	int pd_idx = sh->pd_idx;
3771 	int qd_idx = sh->qd_idx;
3772 	struct r5dev *dev;
3773 
3774 	BUG_ON(sh->batch_head);
3775 	set_bit(STRIPE_HANDLE, &sh->state);
3776 
3777 	BUG_ON(s->failed > 2);
3778 
3779 	/* Want to check and possibly repair P and Q.
3780 	 * However there could be one 'failed' device, in which
3781 	 * case we can only check one of them, possibly using the
3782 	 * other to generate missing data
3783 	 */
3784 
3785 	switch (sh->check_state) {
3786 	case check_state_idle:
3787 		/* start a new check operation if there are < 2 failures */
3788 		if (s->failed == s->q_failed) {
3789 			/* The only possible failed device holds Q, so it
3790 			 * makes sense to check P (If anything else were failed,
3791 			 * we would have used P to recreate it).
3792 			 */
3793 			sh->check_state = check_state_run;
3794 		}
3795 		if (!s->q_failed && s->failed < 2) {
3796 			/* Q is not failed, and we didn't use it to generate
3797 			 * anything, so it makes sense to check it
3798 			 */
3799 			if (sh->check_state == check_state_run)
3800 				sh->check_state = check_state_run_pq;
3801 			else
3802 				sh->check_state = check_state_run_q;
3803 		}
3804 
3805 		/* discard potentially stale zero_sum_result */
3806 		sh->ops.zero_sum_result = 0;
3807 
3808 		if (sh->check_state == check_state_run) {
3809 			/* async_xor_zero_sum destroys the contents of P */
3810 			clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3811 			s->uptodate--;
3812 		}
3813 		if (sh->check_state >= check_state_run &&
3814 		    sh->check_state <= check_state_run_pq) {
3815 			/* async_syndrome_zero_sum preserves P and Q, so
3816 			 * no need to mark them !uptodate here
3817 			 */
3818 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
3819 			break;
3820 		}
3821 
3822 		/* we have 2-disk failure */
3823 		BUG_ON(s->failed != 2);
3824 		/* fall through */
3825 	case check_state_compute_result:
3826 		sh->check_state = check_state_idle;
3827 
3828 		/* check that a write has not made the stripe insync */
3829 		if (test_bit(STRIPE_INSYNC, &sh->state))
3830 			break;
3831 
3832 		/* now write out any block on a failed drive,
3833 		 * or P or Q if they were recomputed
3834 		 */
3835 		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3836 		if (s->failed == 2) {
3837 			dev = &sh->dev[s->failed_num[1]];
3838 			s->locked++;
3839 			set_bit(R5_LOCKED, &dev->flags);
3840 			set_bit(R5_Wantwrite, &dev->flags);
3841 		}
3842 		if (s->failed >= 1) {
3843 			dev = &sh->dev[s->failed_num[0]];
3844 			s->locked++;
3845 			set_bit(R5_LOCKED, &dev->flags);
3846 			set_bit(R5_Wantwrite, &dev->flags);
3847 		}
3848 		if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3849 			dev = &sh->dev[pd_idx];
3850 			s->locked++;
3851 			set_bit(R5_LOCKED, &dev->flags);
3852 			set_bit(R5_Wantwrite, &dev->flags);
3853 		}
3854 		if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3855 			dev = &sh->dev[qd_idx];
3856 			s->locked++;
3857 			set_bit(R5_LOCKED, &dev->flags);
3858 			set_bit(R5_Wantwrite, &dev->flags);
3859 		}
3860 		clear_bit(STRIPE_DEGRADED, &sh->state);
3861 
3862 		set_bit(STRIPE_INSYNC, &sh->state);
3863 		break;
3864 	case check_state_run:
3865 	case check_state_run_q:
3866 	case check_state_run_pq:
3867 		break; /* we will be called again upon completion */
3868 	case check_state_check_result:
3869 		sh->check_state = check_state_idle;
3870 
3871 		/* handle a successful check operation, if parity is correct
3872 		 * we are done.  Otherwise update the mismatch count and repair
3873 		 * parity if !MD_RECOVERY_CHECK
3874 		 */
3875 		if (sh->ops.zero_sum_result == 0) {
3876 			/* both parities are correct */
3877 			if (!s->failed)
3878 				set_bit(STRIPE_INSYNC, &sh->state);
3879 			else {
3880 				/* in contrast to the raid5 case we can validate
3881 				 * parity, but still have a failure to write
3882 				 * back
3883 				 */
3884 				sh->check_state = check_state_compute_result;
3885 				/* Returning at this point means that we may go
3886 				 * off and bring p and/or q uptodate again so
3887 				 * we make sure to check zero_sum_result again
3888 				 * to verify if p or q need writeback
3889 				 */
3890 			}
3891 		} else {
3892 			atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3893 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3894 				/* don't try to repair!! */
3895 				set_bit(STRIPE_INSYNC, &sh->state);
3896 			else {
3897 				int *target = &sh->ops.target;
3898 
3899 				sh->ops.target = -1;
3900 				sh->ops.target2 = -1;
3901 				sh->check_state = check_state_compute_run;
3902 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3903 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3904 				if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3905 					set_bit(R5_Wantcompute,
3906 						&sh->dev[pd_idx].flags);
3907 					*target = pd_idx;
3908 					target = &sh->ops.target2;
3909 					s->uptodate++;
3910 				}
3911 				if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3912 					set_bit(R5_Wantcompute,
3913 						&sh->dev[qd_idx].flags);
3914 					*target = qd_idx;
3915 					s->uptodate++;
3916 				}
3917 			}
3918 		}
3919 		break;
3920 	case check_state_compute_run:
3921 		break;
3922 	default:
3923 		printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3924 		       __func__, sh->check_state,
3925 		       (unsigned long long) sh->sector);
3926 		BUG();
3927 	}
3928 }
3929 
3930 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3931 {
3932 	int i;
3933 
3934 	/* We have read all the blocks in this stripe and now we need to
3935 	 * copy some of them into a target stripe for expand.
3936 	 */
3937 	struct dma_async_tx_descriptor *tx = NULL;
3938 	BUG_ON(sh->batch_head);
3939 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3940 	for (i = 0; i < sh->disks; i++)
3941 		if (i != sh->pd_idx && i != sh->qd_idx) {
3942 			int dd_idx, j;
3943 			struct stripe_head *sh2;
3944 			struct async_submit_ctl submit;
3945 
3946 			sector_t bn = compute_blocknr(sh, i, 1);
3947 			sector_t s = raid5_compute_sector(conf, bn, 0,
3948 							  &dd_idx, NULL);
3949 			sh2 = get_active_stripe(conf, s, 0, 1, 1);
3950 			if (sh2 == NULL)
3951 				/* so far only the early blocks of this stripe
3952 				 * have been requested.  When later blocks
3953 				 * get requested, we will try again
3954 				 */
3955 				continue;
3956 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3957 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3958 				/* must have already done this block */
3959 				release_stripe(sh2);
3960 				continue;
3961 			}
3962 
3963 			/* place all the copies on one channel */
3964 			init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3965 			tx = async_memcpy(sh2->dev[dd_idx].page,
3966 					  sh->dev[i].page, 0, 0, STRIPE_SIZE,
3967 					  &submit);
3968 
3969 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3970 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3971 			for (j = 0; j < conf->raid_disks; j++)
3972 				if (j != sh2->pd_idx &&
3973 				    j != sh2->qd_idx &&
3974 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
3975 					break;
3976 			if (j == conf->raid_disks) {
3977 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
3978 				set_bit(STRIPE_HANDLE, &sh2->state);
3979 			}
3980 			release_stripe(sh2);
3981 
3982 		}
3983 	/* done submitting copies, wait for them to complete */
3984 	async_tx_quiesce(&tx);
3985 }
3986 
3987 /*
3988  * handle_stripe - do things to a stripe.
3989  *
3990  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3991  * state of various bits to see what needs to be done.
3992  * Possible results:
3993  *    return some read requests which now have data
3994  *    return some write requests which are safely on storage
3995  *    schedule a read on some buffers
3996  *    schedule a write of some buffers
3997  *    return confirmation of parity correctness
3998  *
3999  */
4000 
4001 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4002 {
4003 	struct r5conf *conf = sh->raid_conf;
4004 	int disks = sh->disks;
4005 	struct r5dev *dev;
4006 	int i;
4007 	int do_recovery = 0;
4008 
4009 	memset(s, 0, sizeof(*s));
4010 
4011 	s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4012 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4013 	s->failed_num[0] = -1;
4014 	s->failed_num[1] = -1;
4015 
4016 	/* Now to look around and see what can be done */
4017 	rcu_read_lock();
4018 	for (i=disks; i--; ) {
4019 		struct md_rdev *rdev;
4020 		sector_t first_bad;
4021 		int bad_sectors;
4022 		int is_bad = 0;
4023 
4024 		dev = &sh->dev[i];
4025 
4026 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4027 			 i, dev->flags,
4028 			 dev->toread, dev->towrite, dev->written);
4029 		/* maybe we can reply to a read
4030 		 *
4031 		 * new wantfill requests are only permitted while
4032 		 * ops_complete_biofill is guaranteed to be inactive
4033 		 */
4034 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4035 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4036 			set_bit(R5_Wantfill, &dev->flags);
4037 
4038 		/* now count some things */
4039 		if (test_bit(R5_LOCKED, &dev->flags))
4040 			s->locked++;
4041 		if (test_bit(R5_UPTODATE, &dev->flags))
4042 			s->uptodate++;
4043 		if (test_bit(R5_Wantcompute, &dev->flags)) {
4044 			s->compute++;
4045 			BUG_ON(s->compute > 2);
4046 		}
4047 
4048 		if (test_bit(R5_Wantfill, &dev->flags))
4049 			s->to_fill++;
4050 		else if (dev->toread)
4051 			s->to_read++;
4052 		if (dev->towrite) {
4053 			s->to_write++;
4054 			if (!test_bit(R5_OVERWRITE, &dev->flags))
4055 				s->non_overwrite++;
4056 		}
4057 		if (dev->written)
4058 			s->written++;
4059 		/* Prefer to use the replacement for reads, but only
4060 		 * if it is recovered enough and has no bad blocks.
4061 		 */
4062 		rdev = rcu_dereference(conf->disks[i].replacement);
4063 		if (rdev && !test_bit(Faulty, &rdev->flags) &&
4064 		    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4065 		    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4066 				 &first_bad, &bad_sectors))
4067 			set_bit(R5_ReadRepl, &dev->flags);
4068 		else {
4069 			if (rdev && !test_bit(Faulty, &rdev->flags))
4070 				set_bit(R5_NeedReplace, &dev->flags);
4071 			else
4072 				clear_bit(R5_NeedReplace, &dev->flags);
4073 			rdev = rcu_dereference(conf->disks[i].rdev);
4074 			clear_bit(R5_ReadRepl, &dev->flags);
4075 		}
4076 		if (rdev && test_bit(Faulty, &rdev->flags))
4077 			rdev = NULL;
4078 		if (rdev) {
4079 			is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4080 					     &first_bad, &bad_sectors);
4081 			if (s->blocked_rdev == NULL
4082 			    && (test_bit(Blocked, &rdev->flags)
4083 				|| is_bad < 0)) {
4084 				if (is_bad < 0)
4085 					set_bit(BlockedBadBlocks,
4086 						&rdev->flags);
4087 				s->blocked_rdev = rdev;
4088 				atomic_inc(&rdev->nr_pending);
4089 			}
4090 		}
4091 		clear_bit(R5_Insync, &dev->flags);
4092 		if (!rdev)
4093 			/* Not in-sync */;
4094 		else if (is_bad) {
4095 			/* also not in-sync */
4096 			if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4097 			    test_bit(R5_UPTODATE, &dev->flags)) {
4098 				/* treat as in-sync, but with a read error
4099 				 * which we can now try to correct
4100 				 */
4101 				set_bit(R5_Insync, &dev->flags);
4102 				set_bit(R5_ReadError, &dev->flags);
4103 			}
4104 		} else if (test_bit(In_sync, &rdev->flags))
4105 			set_bit(R5_Insync, &dev->flags);
4106 		else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4107 			/* in sync if before recovery_offset */
4108 			set_bit(R5_Insync, &dev->flags);
4109 		else if (test_bit(R5_UPTODATE, &dev->flags) &&
4110 			 test_bit(R5_Expanded, &dev->flags))
4111 			/* If we've reshaped into here, we assume it is Insync.
4112 			 * We will shortly update recovery_offset to make
4113 			 * it official.
4114 			 */
4115 			set_bit(R5_Insync, &dev->flags);
4116 
4117 		if (test_bit(R5_WriteError, &dev->flags)) {
4118 			/* This flag does not apply to '.replacement'
4119 			 * only to .rdev, so make sure to check that*/
4120 			struct md_rdev *rdev2 = rcu_dereference(
4121 				conf->disks[i].rdev);
4122 			if (rdev2 == rdev)
4123 				clear_bit(R5_Insync, &dev->flags);
4124 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4125 				s->handle_bad_blocks = 1;
4126 				atomic_inc(&rdev2->nr_pending);
4127 			} else
4128 				clear_bit(R5_WriteError, &dev->flags);
4129 		}
4130 		if (test_bit(R5_MadeGood, &dev->flags)) {
4131 			/* This flag does not apply to '.replacement'
4132 			 * only to .rdev, so make sure to check that*/
4133 			struct md_rdev *rdev2 = rcu_dereference(
4134 				conf->disks[i].rdev);
4135 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4136 				s->handle_bad_blocks = 1;
4137 				atomic_inc(&rdev2->nr_pending);
4138 			} else
4139 				clear_bit(R5_MadeGood, &dev->flags);
4140 		}
4141 		if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4142 			struct md_rdev *rdev2 = rcu_dereference(
4143 				conf->disks[i].replacement);
4144 			if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4145 				s->handle_bad_blocks = 1;
4146 				atomic_inc(&rdev2->nr_pending);
4147 			} else
4148 				clear_bit(R5_MadeGoodRepl, &dev->flags);
4149 		}
4150 		if (!test_bit(R5_Insync, &dev->flags)) {
4151 			/* The ReadError flag will just be confusing now */
4152 			clear_bit(R5_ReadError, &dev->flags);
4153 			clear_bit(R5_ReWrite, &dev->flags);
4154 		}
4155 		if (test_bit(R5_ReadError, &dev->flags))
4156 			clear_bit(R5_Insync, &dev->flags);
4157 		if (!test_bit(R5_Insync, &dev->flags)) {
4158 			if (s->failed < 2)
4159 				s->failed_num[s->failed] = i;
4160 			s->failed++;
4161 			if (rdev && !test_bit(Faulty, &rdev->flags))
4162 				do_recovery = 1;
4163 		}
4164 	}
4165 	if (test_bit(STRIPE_SYNCING, &sh->state)) {
4166 		/* If there is a failed device being replaced,
4167 		 *     we must be recovering.
4168 		 * else if we are after recovery_cp, we must be syncing
4169 		 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4170 		 * else we can only be replacing
4171 		 * sync and recovery both need to read all devices, and so
4172 		 * use the same flag.
4173 		 */
4174 		if (do_recovery ||
4175 		    sh->sector >= conf->mddev->recovery_cp ||
4176 		    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4177 			s->syncing = 1;
4178 		else
4179 			s->replacing = 1;
4180 	}
4181 	rcu_read_unlock();
4182 }
4183 
4184 static int clear_batch_ready(struct stripe_head *sh)
4185 {
4186 	/* Return '1' if this is a member of batch, or
4187 	 * '0' if it is a lone stripe or a head which can now be
4188 	 * handled.
4189 	 */
4190 	struct stripe_head *tmp;
4191 	if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4192 		return (sh->batch_head && sh->batch_head != sh);
4193 	spin_lock(&sh->stripe_lock);
4194 	if (!sh->batch_head) {
4195 		spin_unlock(&sh->stripe_lock);
4196 		return 0;
4197 	}
4198 
4199 	/*
4200 	 * this stripe could be added to a batch list before we check
4201 	 * BATCH_READY, skips it
4202 	 */
4203 	if (sh->batch_head != sh) {
4204 		spin_unlock(&sh->stripe_lock);
4205 		return 1;
4206 	}
4207 	spin_lock(&sh->batch_lock);
4208 	list_for_each_entry(tmp, &sh->batch_list, batch_list)
4209 		clear_bit(STRIPE_BATCH_READY, &tmp->state);
4210 	spin_unlock(&sh->batch_lock);
4211 	spin_unlock(&sh->stripe_lock);
4212 
4213 	/*
4214 	 * BATCH_READY is cleared, no new stripes can be added.
4215 	 * batch_list can be accessed without lock
4216 	 */
4217 	return 0;
4218 }
4219 
4220 static void break_stripe_batch_list(struct stripe_head *head_sh,
4221 				    unsigned long handle_flags)
4222 {
4223 	struct stripe_head *sh, *next;
4224 	int i;
4225 	int do_wakeup = 0;
4226 
4227 	list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4228 
4229 		list_del_init(&sh->batch_list);
4230 
4231 		WARN_ON_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4232 					  (1 << STRIPE_SYNCING) |
4233 					  (1 << STRIPE_REPLACED) |
4234 					  (1 << STRIPE_PREREAD_ACTIVE) |
4235 					  (1 << STRIPE_DELAYED) |
4236 					  (1 << STRIPE_BIT_DELAY) |
4237 					  (1 << STRIPE_FULL_WRITE) |
4238 					  (1 << STRIPE_BIOFILL_RUN) |
4239 					  (1 << STRIPE_COMPUTE_RUN)  |
4240 					  (1 << STRIPE_OPS_REQ_PENDING) |
4241 					  (1 << STRIPE_DISCARD) |
4242 					  (1 << STRIPE_BATCH_READY) |
4243 					  (1 << STRIPE_BATCH_ERR) |
4244 					  (1 << STRIPE_BITMAP_PENDING)));
4245 		WARN_ON_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4246 					      (1 << STRIPE_REPLACED)));
4247 
4248 		set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4249 					    (1 << STRIPE_DEGRADED)),
4250 			      head_sh->state & (1 << STRIPE_INSYNC));
4251 
4252 		sh->check_state = head_sh->check_state;
4253 		sh->reconstruct_state = head_sh->reconstruct_state;
4254 		for (i = 0; i < sh->disks; i++) {
4255 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4256 				do_wakeup = 1;
4257 			sh->dev[i].flags = head_sh->dev[i].flags &
4258 				(~((1 << R5_WriteError) | (1 << R5_Overlap)));
4259 		}
4260 		spin_lock_irq(&sh->stripe_lock);
4261 		sh->batch_head = NULL;
4262 		spin_unlock_irq(&sh->stripe_lock);
4263 		if (handle_flags == 0 ||
4264 		    sh->state & handle_flags)
4265 			set_bit(STRIPE_HANDLE, &sh->state);
4266 		release_stripe(sh);
4267 	}
4268 	spin_lock_irq(&head_sh->stripe_lock);
4269 	head_sh->batch_head = NULL;
4270 	spin_unlock_irq(&head_sh->stripe_lock);
4271 	for (i = 0; i < head_sh->disks; i++)
4272 		if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4273 			do_wakeup = 1;
4274 	if (head_sh->state & handle_flags)
4275 		set_bit(STRIPE_HANDLE, &head_sh->state);
4276 
4277 	if (do_wakeup)
4278 		wake_up(&head_sh->raid_conf->wait_for_overlap);
4279 }
4280 
4281 static void handle_stripe(struct stripe_head *sh)
4282 {
4283 	struct stripe_head_state s;
4284 	struct r5conf *conf = sh->raid_conf;
4285 	int i;
4286 	int prexor;
4287 	int disks = sh->disks;
4288 	struct r5dev *pdev, *qdev;
4289 
4290 	clear_bit(STRIPE_HANDLE, &sh->state);
4291 	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4292 		/* already being handled, ensure it gets handled
4293 		 * again when current action finishes */
4294 		set_bit(STRIPE_HANDLE, &sh->state);
4295 		return;
4296 	}
4297 
4298 	if (clear_batch_ready(sh) ) {
4299 		clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4300 		return;
4301 	}
4302 
4303 	if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4304 		break_stripe_batch_list(sh, 0);
4305 
4306 	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4307 		spin_lock(&sh->stripe_lock);
4308 		/* Cannot process 'sync' concurrently with 'discard' */
4309 		if (!test_bit(STRIPE_DISCARD, &sh->state) &&
4310 		    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4311 			set_bit(STRIPE_SYNCING, &sh->state);
4312 			clear_bit(STRIPE_INSYNC, &sh->state);
4313 			clear_bit(STRIPE_REPLACED, &sh->state);
4314 		}
4315 		spin_unlock(&sh->stripe_lock);
4316 	}
4317 	clear_bit(STRIPE_DELAYED, &sh->state);
4318 
4319 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4320 		"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4321 	       (unsigned long long)sh->sector, sh->state,
4322 	       atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4323 	       sh->check_state, sh->reconstruct_state);
4324 
4325 	analyse_stripe(sh, &s);
4326 
4327 	if (s.handle_bad_blocks) {
4328 		set_bit(STRIPE_HANDLE, &sh->state);
4329 		goto finish;
4330 	}
4331 
4332 	if (unlikely(s.blocked_rdev)) {
4333 		if (s.syncing || s.expanding || s.expanded ||
4334 		    s.replacing || s.to_write || s.written) {
4335 			set_bit(STRIPE_HANDLE, &sh->state);
4336 			goto finish;
4337 		}
4338 		/* There is nothing for the blocked_rdev to block */
4339 		rdev_dec_pending(s.blocked_rdev, conf->mddev);
4340 		s.blocked_rdev = NULL;
4341 	}
4342 
4343 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4344 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4345 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4346 	}
4347 
4348 	pr_debug("locked=%d uptodate=%d to_read=%d"
4349 	       " to_write=%d failed=%d failed_num=%d,%d\n",
4350 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4351 	       s.failed_num[0], s.failed_num[1]);
4352 	/* check if the array has lost more than max_degraded devices and,
4353 	 * if so, some requests might need to be failed.
4354 	 */
4355 	if (s.failed > conf->max_degraded) {
4356 		sh->check_state = 0;
4357 		sh->reconstruct_state = 0;
4358 		break_stripe_batch_list(sh, 0);
4359 		if (s.to_read+s.to_write+s.written)
4360 			handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
4361 		if (s.syncing + s.replacing)
4362 			handle_failed_sync(conf, sh, &s);
4363 	}
4364 
4365 	/* Now we check to see if any write operations have recently
4366 	 * completed
4367 	 */
4368 	prexor = 0;
4369 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4370 		prexor = 1;
4371 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
4372 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4373 		sh->reconstruct_state = reconstruct_state_idle;
4374 
4375 		/* All the 'written' buffers and the parity block are ready to
4376 		 * be written back to disk
4377 		 */
4378 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4379 		       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4380 		BUG_ON(sh->qd_idx >= 0 &&
4381 		       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4382 		       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4383 		for (i = disks; i--; ) {
4384 			struct r5dev *dev = &sh->dev[i];
4385 			if (test_bit(R5_LOCKED, &dev->flags) &&
4386 				(i == sh->pd_idx || i == sh->qd_idx ||
4387 				 dev->written)) {
4388 				pr_debug("Writing block %d\n", i);
4389 				set_bit(R5_Wantwrite, &dev->flags);
4390 				if (prexor)
4391 					continue;
4392 				if (s.failed > 1)
4393 					continue;
4394 				if (!test_bit(R5_Insync, &dev->flags) ||
4395 				    ((i == sh->pd_idx || i == sh->qd_idx)  &&
4396 				     s.failed == 0))
4397 					set_bit(STRIPE_INSYNC, &sh->state);
4398 			}
4399 		}
4400 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4401 			s.dec_preread_active = 1;
4402 	}
4403 
4404 	/*
4405 	 * might be able to return some write requests if the parity blocks
4406 	 * are safe, or on a failed drive
4407 	 */
4408 	pdev = &sh->dev[sh->pd_idx];
4409 	s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4410 		|| (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4411 	qdev = &sh->dev[sh->qd_idx];
4412 	s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4413 		|| (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4414 		|| conf->level < 6;
4415 
4416 	if (s.written &&
4417 	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4418 			     && !test_bit(R5_LOCKED, &pdev->flags)
4419 			     && (test_bit(R5_UPTODATE, &pdev->flags) ||
4420 				 test_bit(R5_Discard, &pdev->flags))))) &&
4421 	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4422 			     && !test_bit(R5_LOCKED, &qdev->flags)
4423 			     && (test_bit(R5_UPTODATE, &qdev->flags) ||
4424 				 test_bit(R5_Discard, &qdev->flags))))))
4425 		handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
4426 
4427 	/* Now we might consider reading some blocks, either to check/generate
4428 	 * parity, or to satisfy requests
4429 	 * or to load a block that is being partially written.
4430 	 */
4431 	if (s.to_read || s.non_overwrite
4432 	    || (conf->level == 6 && s.to_write && s.failed)
4433 	    || (s.syncing && (s.uptodate + s.compute < disks))
4434 	    || s.replacing
4435 	    || s.expanding)
4436 		handle_stripe_fill(sh, &s, disks);
4437 
4438 	/* Now to consider new write requests and what else, if anything
4439 	 * should be read.  We do not handle new writes when:
4440 	 * 1/ A 'write' operation (copy+xor) is already in flight.
4441 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
4442 	 *    block.
4443 	 */
4444 	if (s.to_write && !sh->reconstruct_state && !sh->check_state)
4445 		handle_stripe_dirtying(conf, sh, &s, disks);
4446 
4447 	/* maybe we need to check and possibly fix the parity for this stripe
4448 	 * Any reads will already have been scheduled, so we just see if enough
4449 	 * data is available.  The parity check is held off while parity
4450 	 * dependent operations are in flight.
4451 	 */
4452 	if (sh->check_state ||
4453 	    (s.syncing && s.locked == 0 &&
4454 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4455 	     !test_bit(STRIPE_INSYNC, &sh->state))) {
4456 		if (conf->level == 6)
4457 			handle_parity_checks6(conf, sh, &s, disks);
4458 		else
4459 			handle_parity_checks5(conf, sh, &s, disks);
4460 	}
4461 
4462 	if ((s.replacing || s.syncing) && s.locked == 0
4463 	    && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4464 	    && !test_bit(STRIPE_REPLACED, &sh->state)) {
4465 		/* Write out to replacement devices where possible */
4466 		for (i = 0; i < conf->raid_disks; i++)
4467 			if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4468 				WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4469 				set_bit(R5_WantReplace, &sh->dev[i].flags);
4470 				set_bit(R5_LOCKED, &sh->dev[i].flags);
4471 				s.locked++;
4472 			}
4473 		if (s.replacing)
4474 			set_bit(STRIPE_INSYNC, &sh->state);
4475 		set_bit(STRIPE_REPLACED, &sh->state);
4476 	}
4477 	if ((s.syncing || s.replacing) && s.locked == 0 &&
4478 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4479 	    test_bit(STRIPE_INSYNC, &sh->state)) {
4480 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4481 		clear_bit(STRIPE_SYNCING, &sh->state);
4482 		if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4483 			wake_up(&conf->wait_for_overlap);
4484 	}
4485 
4486 	/* If the failed drives are just a ReadError, then we might need
4487 	 * to progress the repair/check process
4488 	 */
4489 	if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4490 		for (i = 0; i < s.failed; i++) {
4491 			struct r5dev *dev = &sh->dev[s.failed_num[i]];
4492 			if (test_bit(R5_ReadError, &dev->flags)
4493 			    && !test_bit(R5_LOCKED, &dev->flags)
4494 			    && test_bit(R5_UPTODATE, &dev->flags)
4495 				) {
4496 				if (!test_bit(R5_ReWrite, &dev->flags)) {
4497 					set_bit(R5_Wantwrite, &dev->flags);
4498 					set_bit(R5_ReWrite, &dev->flags);
4499 					set_bit(R5_LOCKED, &dev->flags);
4500 					s.locked++;
4501 				} else {
4502 					/* let's read it back */
4503 					set_bit(R5_Wantread, &dev->flags);
4504 					set_bit(R5_LOCKED, &dev->flags);
4505 					s.locked++;
4506 				}
4507 			}
4508 		}
4509 
4510 	/* Finish reconstruct operations initiated by the expansion process */
4511 	if (sh->reconstruct_state == reconstruct_state_result) {
4512 		struct stripe_head *sh_src
4513 			= get_active_stripe(conf, sh->sector, 1, 1, 1);
4514 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4515 			/* sh cannot be written until sh_src has been read.
4516 			 * so arrange for sh to be delayed a little
4517 			 */
4518 			set_bit(STRIPE_DELAYED, &sh->state);
4519 			set_bit(STRIPE_HANDLE, &sh->state);
4520 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4521 					      &sh_src->state))
4522 				atomic_inc(&conf->preread_active_stripes);
4523 			release_stripe(sh_src);
4524 			goto finish;
4525 		}
4526 		if (sh_src)
4527 			release_stripe(sh_src);
4528 
4529 		sh->reconstruct_state = reconstruct_state_idle;
4530 		clear_bit(STRIPE_EXPANDING, &sh->state);
4531 		for (i = conf->raid_disks; i--; ) {
4532 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
4533 			set_bit(R5_LOCKED, &sh->dev[i].flags);
4534 			s.locked++;
4535 		}
4536 	}
4537 
4538 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4539 	    !sh->reconstruct_state) {
4540 		/* Need to write out all blocks after computing parity */
4541 		sh->disks = conf->raid_disks;
4542 		stripe_set_idx(sh->sector, conf, 0, sh);
4543 		schedule_reconstruction(sh, &s, 1, 1);
4544 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4545 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
4546 		atomic_dec(&conf->reshape_stripes);
4547 		wake_up(&conf->wait_for_overlap);
4548 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4549 	}
4550 
4551 	if (s.expanding && s.locked == 0 &&
4552 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4553 		handle_stripe_expansion(conf, sh);
4554 
4555 finish:
4556 	/* wait for this device to become unblocked */
4557 	if (unlikely(s.blocked_rdev)) {
4558 		if (conf->mddev->external)
4559 			md_wait_for_blocked_rdev(s.blocked_rdev,
4560 						 conf->mddev);
4561 		else
4562 			/* Internal metadata will immediately
4563 			 * be written by raid5d, so we don't
4564 			 * need to wait here.
4565 			 */
4566 			rdev_dec_pending(s.blocked_rdev,
4567 					 conf->mddev);
4568 	}
4569 
4570 	if (s.handle_bad_blocks)
4571 		for (i = disks; i--; ) {
4572 			struct md_rdev *rdev;
4573 			struct r5dev *dev = &sh->dev[i];
4574 			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4575 				/* We own a safe reference to the rdev */
4576 				rdev = conf->disks[i].rdev;
4577 				if (!rdev_set_badblocks(rdev, sh->sector,
4578 							STRIPE_SECTORS, 0))
4579 					md_error(conf->mddev, rdev);
4580 				rdev_dec_pending(rdev, conf->mddev);
4581 			}
4582 			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4583 				rdev = conf->disks[i].rdev;
4584 				rdev_clear_badblocks(rdev, sh->sector,
4585 						     STRIPE_SECTORS, 0);
4586 				rdev_dec_pending(rdev, conf->mddev);
4587 			}
4588 			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4589 				rdev = conf->disks[i].replacement;
4590 				if (!rdev)
4591 					/* rdev have been moved down */
4592 					rdev = conf->disks[i].rdev;
4593 				rdev_clear_badblocks(rdev, sh->sector,
4594 						     STRIPE_SECTORS, 0);
4595 				rdev_dec_pending(rdev, conf->mddev);
4596 			}
4597 		}
4598 
4599 	if (s.ops_request)
4600 		raid_run_ops(sh, s.ops_request);
4601 
4602 	ops_run_io(sh, &s);
4603 
4604 	if (s.dec_preread_active) {
4605 		/* We delay this until after ops_run_io so that if make_request
4606 		 * is waiting on a flush, it won't continue until the writes
4607 		 * have actually been submitted.
4608 		 */
4609 		atomic_dec(&conf->preread_active_stripes);
4610 		if (atomic_read(&conf->preread_active_stripes) <
4611 		    IO_THRESHOLD)
4612 			md_wakeup_thread(conf->mddev->thread);
4613 	}
4614 
4615 	return_io(s.return_bi);
4616 
4617 	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4618 }
4619 
4620 static void raid5_activate_delayed(struct r5conf *conf)
4621 {
4622 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4623 		while (!list_empty(&conf->delayed_list)) {
4624 			struct list_head *l = conf->delayed_list.next;
4625 			struct stripe_head *sh;
4626 			sh = list_entry(l, struct stripe_head, lru);
4627 			list_del_init(l);
4628 			clear_bit(STRIPE_DELAYED, &sh->state);
4629 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4630 				atomic_inc(&conf->preread_active_stripes);
4631 			list_add_tail(&sh->lru, &conf->hold_list);
4632 			raid5_wakeup_stripe_thread(sh);
4633 		}
4634 	}
4635 }
4636 
4637 static void activate_bit_delay(struct r5conf *conf,
4638 	struct list_head *temp_inactive_list)
4639 {
4640 	/* device_lock is held */
4641 	struct list_head head;
4642 	list_add(&head, &conf->bitmap_list);
4643 	list_del_init(&conf->bitmap_list);
4644 	while (!list_empty(&head)) {
4645 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4646 		int hash;
4647 		list_del_init(&sh->lru);
4648 		atomic_inc(&sh->count);
4649 		hash = sh->hash_lock_index;
4650 		__release_stripe(conf, sh, &temp_inactive_list[hash]);
4651 	}
4652 }
4653 
4654 static int raid5_congested(struct mddev *mddev, int bits)
4655 {
4656 	struct r5conf *conf = mddev->private;
4657 
4658 	/* No difference between reads and writes.  Just check
4659 	 * how busy the stripe_cache is
4660 	 */
4661 
4662 	if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
4663 		return 1;
4664 	if (conf->quiesce)
4665 		return 1;
4666 	if (atomic_read(&conf->empty_inactive_list_nr))
4667 		return 1;
4668 
4669 	return 0;
4670 }
4671 
4672 /* We want read requests to align with chunks where possible,
4673  * but write requests don't need to.
4674  */
4675 static int raid5_mergeable_bvec(struct mddev *mddev,
4676 				struct bvec_merge_data *bvm,
4677 				struct bio_vec *biovec)
4678 {
4679 	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
4680 	int max;
4681 	unsigned int chunk_sectors = mddev->chunk_sectors;
4682 	unsigned int bio_sectors = bvm->bi_size >> 9;
4683 
4684 	/*
4685 	 * always allow writes to be mergeable, read as well if array
4686 	 * is degraded as we'll go through stripe cache anyway.
4687 	 */
4688 	if ((bvm->bi_rw & 1) == WRITE || mddev->degraded)
4689 		return biovec->bv_len;
4690 
4691 	if (mddev->new_chunk_sectors < mddev->chunk_sectors)
4692 		chunk_sectors = mddev->new_chunk_sectors;
4693 	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
4694 	if (max < 0) max = 0;
4695 	if (max <= biovec->bv_len && bio_sectors == 0)
4696 		return biovec->bv_len;
4697 	else
4698 		return max;
4699 }
4700 
4701 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4702 {
4703 	sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4704 	unsigned int chunk_sectors = mddev->chunk_sectors;
4705 	unsigned int bio_sectors = bio_sectors(bio);
4706 
4707 	if (mddev->new_chunk_sectors < mddev->chunk_sectors)
4708 		chunk_sectors = mddev->new_chunk_sectors;
4709 	return  chunk_sectors >=
4710 		((sector & (chunk_sectors - 1)) + bio_sectors);
4711 }
4712 
4713 /*
4714  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4715  *  later sampled by raid5d.
4716  */
4717 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4718 {
4719 	unsigned long flags;
4720 
4721 	spin_lock_irqsave(&conf->device_lock, flags);
4722 
4723 	bi->bi_next = conf->retry_read_aligned_list;
4724 	conf->retry_read_aligned_list = bi;
4725 
4726 	spin_unlock_irqrestore(&conf->device_lock, flags);
4727 	md_wakeup_thread(conf->mddev->thread);
4728 }
4729 
4730 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4731 {
4732 	struct bio *bi;
4733 
4734 	bi = conf->retry_read_aligned;
4735 	if (bi) {
4736 		conf->retry_read_aligned = NULL;
4737 		return bi;
4738 	}
4739 	bi = conf->retry_read_aligned_list;
4740 	if(bi) {
4741 		conf->retry_read_aligned_list = bi->bi_next;
4742 		bi->bi_next = NULL;
4743 		/*
4744 		 * this sets the active strip count to 1 and the processed
4745 		 * strip count to zero (upper 8 bits)
4746 		 */
4747 		raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
4748 	}
4749 
4750 	return bi;
4751 }
4752 
4753 /*
4754  *  The "raid5_align_endio" should check if the read succeeded and if it
4755  *  did, call bio_endio on the original bio (having bio_put the new bio
4756  *  first).
4757  *  If the read failed..
4758  */
4759 static void raid5_align_endio(struct bio *bi, int error)
4760 {
4761 	struct bio* raid_bi  = bi->bi_private;
4762 	struct mddev *mddev;
4763 	struct r5conf *conf;
4764 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
4765 	struct md_rdev *rdev;
4766 
4767 	bio_put(bi);
4768 
4769 	rdev = (void*)raid_bi->bi_next;
4770 	raid_bi->bi_next = NULL;
4771 	mddev = rdev->mddev;
4772 	conf = mddev->private;
4773 
4774 	rdev_dec_pending(rdev, conf->mddev);
4775 
4776 	if (!error && uptodate) {
4777 		trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
4778 					 raid_bi, 0);
4779 		bio_endio(raid_bi, 0);
4780 		if (atomic_dec_and_test(&conf->active_aligned_reads))
4781 			wake_up(&conf->wait_for_quiescent);
4782 		return;
4783 	}
4784 
4785 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
4786 
4787 	add_bio_to_retry(raid_bi, conf);
4788 }
4789 
4790 static int bio_fits_rdev(struct bio *bi)
4791 {
4792 	struct request_queue *q = bdev_get_queue(bi->bi_bdev);
4793 
4794 	if (bio_sectors(bi) > queue_max_sectors(q))
4795 		return 0;
4796 	blk_recount_segments(q, bi);
4797 	if (bi->bi_phys_segments > queue_max_segments(q))
4798 		return 0;
4799 
4800 	if (q->merge_bvec_fn)
4801 		/* it's too hard to apply the merge_bvec_fn at this stage,
4802 		 * just just give up
4803 		 */
4804 		return 0;
4805 
4806 	return 1;
4807 }
4808 
4809 static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
4810 {
4811 	struct r5conf *conf = mddev->private;
4812 	int dd_idx;
4813 	struct bio* align_bi;
4814 	struct md_rdev *rdev;
4815 	sector_t end_sector;
4816 
4817 	if (!in_chunk_boundary(mddev, raid_bio)) {
4818 		pr_debug("chunk_aligned_read : non aligned\n");
4819 		return 0;
4820 	}
4821 	/*
4822 	 * use bio_clone_mddev to make a copy of the bio
4823 	 */
4824 	align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4825 	if (!align_bi)
4826 		return 0;
4827 	/*
4828 	 *   set bi_end_io to a new function, and set bi_private to the
4829 	 *     original bio.
4830 	 */
4831 	align_bi->bi_end_io  = raid5_align_endio;
4832 	align_bi->bi_private = raid_bio;
4833 	/*
4834 	 *	compute position
4835 	 */
4836 	align_bi->bi_iter.bi_sector =
4837 		raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
4838 				     0, &dd_idx, NULL);
4839 
4840 	end_sector = bio_end_sector(align_bi);
4841 	rcu_read_lock();
4842 	rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4843 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
4844 	    rdev->recovery_offset < end_sector) {
4845 		rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4846 		if (rdev &&
4847 		    (test_bit(Faulty, &rdev->flags) ||
4848 		    !(test_bit(In_sync, &rdev->flags) ||
4849 		      rdev->recovery_offset >= end_sector)))
4850 			rdev = NULL;
4851 	}
4852 	if (rdev) {
4853 		sector_t first_bad;
4854 		int bad_sectors;
4855 
4856 		atomic_inc(&rdev->nr_pending);
4857 		rcu_read_unlock();
4858 		raid_bio->bi_next = (void*)rdev;
4859 		align_bi->bi_bdev =  rdev->bdev;
4860 		__clear_bit(BIO_SEG_VALID, &align_bi->bi_flags);
4861 
4862 		if (!bio_fits_rdev(align_bi) ||
4863 		    is_badblock(rdev, align_bi->bi_iter.bi_sector,
4864 				bio_sectors(align_bi),
4865 				&first_bad, &bad_sectors)) {
4866 			/* too big in some way, or has a known bad block */
4867 			bio_put(align_bi);
4868 			rdev_dec_pending(rdev, mddev);
4869 			return 0;
4870 		}
4871 
4872 		/* No reshape active, so we can trust rdev->data_offset */
4873 		align_bi->bi_iter.bi_sector += rdev->data_offset;
4874 
4875 		spin_lock_irq(&conf->device_lock);
4876 		wait_event_lock_irq(conf->wait_for_quiescent,
4877 				    conf->quiesce == 0,
4878 				    conf->device_lock);
4879 		atomic_inc(&conf->active_aligned_reads);
4880 		spin_unlock_irq(&conf->device_lock);
4881 
4882 		if (mddev->gendisk)
4883 			trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4884 					      align_bi, disk_devt(mddev->gendisk),
4885 					      raid_bio->bi_iter.bi_sector);
4886 		generic_make_request(align_bi);
4887 		return 1;
4888 	} else {
4889 		rcu_read_unlock();
4890 		bio_put(align_bi);
4891 		return 0;
4892 	}
4893 }
4894 
4895 /* __get_priority_stripe - get the next stripe to process
4896  *
4897  * Full stripe writes are allowed to pass preread active stripes up until
4898  * the bypass_threshold is exceeded.  In general the bypass_count
4899  * increments when the handle_list is handled before the hold_list; however, it
4900  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4901  * stripe with in flight i/o.  The bypass_count will be reset when the
4902  * head of the hold_list has changed, i.e. the head was promoted to the
4903  * handle_list.
4904  */
4905 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
4906 {
4907 	struct stripe_head *sh = NULL, *tmp;
4908 	struct list_head *handle_list = NULL;
4909 	struct r5worker_group *wg = NULL;
4910 
4911 	if (conf->worker_cnt_per_group == 0) {
4912 		handle_list = &conf->handle_list;
4913 	} else if (group != ANY_GROUP) {
4914 		handle_list = &conf->worker_groups[group].handle_list;
4915 		wg = &conf->worker_groups[group];
4916 	} else {
4917 		int i;
4918 		for (i = 0; i < conf->group_cnt; i++) {
4919 			handle_list = &conf->worker_groups[i].handle_list;
4920 			wg = &conf->worker_groups[i];
4921 			if (!list_empty(handle_list))
4922 				break;
4923 		}
4924 	}
4925 
4926 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4927 		  __func__,
4928 		  list_empty(handle_list) ? "empty" : "busy",
4929 		  list_empty(&conf->hold_list) ? "empty" : "busy",
4930 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
4931 
4932 	if (!list_empty(handle_list)) {
4933 		sh = list_entry(handle_list->next, typeof(*sh), lru);
4934 
4935 		if (list_empty(&conf->hold_list))
4936 			conf->bypass_count = 0;
4937 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4938 			if (conf->hold_list.next == conf->last_hold)
4939 				conf->bypass_count++;
4940 			else {
4941 				conf->last_hold = conf->hold_list.next;
4942 				conf->bypass_count -= conf->bypass_threshold;
4943 				if (conf->bypass_count < 0)
4944 					conf->bypass_count = 0;
4945 			}
4946 		}
4947 	} else if (!list_empty(&conf->hold_list) &&
4948 		   ((conf->bypass_threshold &&
4949 		     conf->bypass_count > conf->bypass_threshold) ||
4950 		    atomic_read(&conf->pending_full_writes) == 0)) {
4951 
4952 		list_for_each_entry(tmp, &conf->hold_list,  lru) {
4953 			if (conf->worker_cnt_per_group == 0 ||
4954 			    group == ANY_GROUP ||
4955 			    !cpu_online(tmp->cpu) ||
4956 			    cpu_to_group(tmp->cpu) == group) {
4957 				sh = tmp;
4958 				break;
4959 			}
4960 		}
4961 
4962 		if (sh) {
4963 			conf->bypass_count -= conf->bypass_threshold;
4964 			if (conf->bypass_count < 0)
4965 				conf->bypass_count = 0;
4966 		}
4967 		wg = NULL;
4968 	}
4969 
4970 	if (!sh)
4971 		return NULL;
4972 
4973 	if (wg) {
4974 		wg->stripes_cnt--;
4975 		sh->group = NULL;
4976 	}
4977 	list_del_init(&sh->lru);
4978 	BUG_ON(atomic_inc_return(&sh->count) != 1);
4979 	return sh;
4980 }
4981 
4982 struct raid5_plug_cb {
4983 	struct blk_plug_cb	cb;
4984 	struct list_head	list;
4985 	struct list_head	temp_inactive_list[NR_STRIPE_HASH_LOCKS];
4986 };
4987 
4988 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4989 {
4990 	struct raid5_plug_cb *cb = container_of(
4991 		blk_cb, struct raid5_plug_cb, cb);
4992 	struct stripe_head *sh;
4993 	struct mddev *mddev = cb->cb.data;
4994 	struct r5conf *conf = mddev->private;
4995 	int cnt = 0;
4996 	int hash;
4997 
4998 	if (cb->list.next && !list_empty(&cb->list)) {
4999 		spin_lock_irq(&conf->device_lock);
5000 		while (!list_empty(&cb->list)) {
5001 			sh = list_first_entry(&cb->list, struct stripe_head, lru);
5002 			list_del_init(&sh->lru);
5003 			/*
5004 			 * avoid race release_stripe_plug() sees
5005 			 * STRIPE_ON_UNPLUG_LIST clear but the stripe
5006 			 * is still in our list
5007 			 */
5008 			smp_mb__before_atomic();
5009 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5010 			/*
5011 			 * STRIPE_ON_RELEASE_LIST could be set here. In that
5012 			 * case, the count is always > 1 here
5013 			 */
5014 			hash = sh->hash_lock_index;
5015 			__release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5016 			cnt++;
5017 		}
5018 		spin_unlock_irq(&conf->device_lock);
5019 	}
5020 	release_inactive_stripe_list(conf, cb->temp_inactive_list,
5021 				     NR_STRIPE_HASH_LOCKS);
5022 	if (mddev->queue)
5023 		trace_block_unplug(mddev->queue, cnt, !from_schedule);
5024 	kfree(cb);
5025 }
5026 
5027 static void release_stripe_plug(struct mddev *mddev,
5028 				struct stripe_head *sh)
5029 {
5030 	struct blk_plug_cb *blk_cb = blk_check_plugged(
5031 		raid5_unplug, mddev,
5032 		sizeof(struct raid5_plug_cb));
5033 	struct raid5_plug_cb *cb;
5034 
5035 	if (!blk_cb) {
5036 		release_stripe(sh);
5037 		return;
5038 	}
5039 
5040 	cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5041 
5042 	if (cb->list.next == NULL) {
5043 		int i;
5044 		INIT_LIST_HEAD(&cb->list);
5045 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5046 			INIT_LIST_HEAD(cb->temp_inactive_list + i);
5047 	}
5048 
5049 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5050 		list_add_tail(&sh->lru, &cb->list);
5051 	else
5052 		release_stripe(sh);
5053 }
5054 
5055 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5056 {
5057 	struct r5conf *conf = mddev->private;
5058 	sector_t logical_sector, last_sector;
5059 	struct stripe_head *sh;
5060 	int remaining;
5061 	int stripe_sectors;
5062 
5063 	if (mddev->reshape_position != MaxSector)
5064 		/* Skip discard while reshape is happening */
5065 		return;
5066 
5067 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5068 	last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5069 
5070 	bi->bi_next = NULL;
5071 	bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
5072 
5073 	stripe_sectors = conf->chunk_sectors *
5074 		(conf->raid_disks - conf->max_degraded);
5075 	logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5076 					       stripe_sectors);
5077 	sector_div(last_sector, stripe_sectors);
5078 
5079 	logical_sector *= conf->chunk_sectors;
5080 	last_sector *= conf->chunk_sectors;
5081 
5082 	for (; logical_sector < last_sector;
5083 	     logical_sector += STRIPE_SECTORS) {
5084 		DEFINE_WAIT(w);
5085 		int d;
5086 	again:
5087 		sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
5088 		prepare_to_wait(&conf->wait_for_overlap, &w,
5089 				TASK_UNINTERRUPTIBLE);
5090 		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5091 		if (test_bit(STRIPE_SYNCING, &sh->state)) {
5092 			release_stripe(sh);
5093 			schedule();
5094 			goto again;
5095 		}
5096 		clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5097 		spin_lock_irq(&sh->stripe_lock);
5098 		for (d = 0; d < conf->raid_disks; d++) {
5099 			if (d == sh->pd_idx || d == sh->qd_idx)
5100 				continue;
5101 			if (sh->dev[d].towrite || sh->dev[d].toread) {
5102 				set_bit(R5_Overlap, &sh->dev[d].flags);
5103 				spin_unlock_irq(&sh->stripe_lock);
5104 				release_stripe(sh);
5105 				schedule();
5106 				goto again;
5107 			}
5108 		}
5109 		set_bit(STRIPE_DISCARD, &sh->state);
5110 		finish_wait(&conf->wait_for_overlap, &w);
5111 		sh->overwrite_disks = 0;
5112 		for (d = 0; d < conf->raid_disks; d++) {
5113 			if (d == sh->pd_idx || d == sh->qd_idx)
5114 				continue;
5115 			sh->dev[d].towrite = bi;
5116 			set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5117 			raid5_inc_bi_active_stripes(bi);
5118 			sh->overwrite_disks++;
5119 		}
5120 		spin_unlock_irq(&sh->stripe_lock);
5121 		if (conf->mddev->bitmap) {
5122 			for (d = 0;
5123 			     d < conf->raid_disks - conf->max_degraded;
5124 			     d++)
5125 				bitmap_startwrite(mddev->bitmap,
5126 						  sh->sector,
5127 						  STRIPE_SECTORS,
5128 						  0);
5129 			sh->bm_seq = conf->seq_flush + 1;
5130 			set_bit(STRIPE_BIT_DELAY, &sh->state);
5131 		}
5132 
5133 		set_bit(STRIPE_HANDLE, &sh->state);
5134 		clear_bit(STRIPE_DELAYED, &sh->state);
5135 		if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5136 			atomic_inc(&conf->preread_active_stripes);
5137 		release_stripe_plug(mddev, sh);
5138 	}
5139 
5140 	remaining = raid5_dec_bi_active_stripes(bi);
5141 	if (remaining == 0) {
5142 		md_write_end(mddev);
5143 		bio_endio(bi, 0);
5144 	}
5145 }
5146 
5147 static void make_request(struct mddev *mddev, struct bio * bi)
5148 {
5149 	struct r5conf *conf = mddev->private;
5150 	int dd_idx;
5151 	sector_t new_sector;
5152 	sector_t logical_sector, last_sector;
5153 	struct stripe_head *sh;
5154 	const int rw = bio_data_dir(bi);
5155 	int remaining;
5156 	DEFINE_WAIT(w);
5157 	bool do_prepare;
5158 
5159 	if (unlikely(bi->bi_rw & REQ_FLUSH)) {
5160 		md_flush_request(mddev, bi);
5161 		return;
5162 	}
5163 
5164 	md_write_start(mddev, bi);
5165 
5166 	/*
5167 	 * If array is degraded, better not do chunk aligned read because
5168 	 * later we might have to read it again in order to reconstruct
5169 	 * data on failed drives.
5170 	 */
5171 	if (rw == READ && mddev->degraded == 0 &&
5172 	     mddev->reshape_position == MaxSector &&
5173 	     chunk_aligned_read(mddev,bi))
5174 		return;
5175 
5176 	if (unlikely(bi->bi_rw & REQ_DISCARD)) {
5177 		make_discard_request(mddev, bi);
5178 		return;
5179 	}
5180 
5181 	logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5182 	last_sector = bio_end_sector(bi);
5183 	bi->bi_next = NULL;
5184 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
5185 
5186 	prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5187 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5188 		int previous;
5189 		int seq;
5190 
5191 		do_prepare = false;
5192 	retry:
5193 		seq = read_seqcount_begin(&conf->gen_lock);
5194 		previous = 0;
5195 		if (do_prepare)
5196 			prepare_to_wait(&conf->wait_for_overlap, &w,
5197 				TASK_UNINTERRUPTIBLE);
5198 		if (unlikely(conf->reshape_progress != MaxSector)) {
5199 			/* spinlock is needed as reshape_progress may be
5200 			 * 64bit on a 32bit platform, and so it might be
5201 			 * possible to see a half-updated value
5202 			 * Of course reshape_progress could change after
5203 			 * the lock is dropped, so once we get a reference
5204 			 * to the stripe that we think it is, we will have
5205 			 * to check again.
5206 			 */
5207 			spin_lock_irq(&conf->device_lock);
5208 			if (mddev->reshape_backwards
5209 			    ? logical_sector < conf->reshape_progress
5210 			    : logical_sector >= conf->reshape_progress) {
5211 				previous = 1;
5212 			} else {
5213 				if (mddev->reshape_backwards
5214 				    ? logical_sector < conf->reshape_safe
5215 				    : logical_sector >= conf->reshape_safe) {
5216 					spin_unlock_irq(&conf->device_lock);
5217 					schedule();
5218 					do_prepare = true;
5219 					goto retry;
5220 				}
5221 			}
5222 			spin_unlock_irq(&conf->device_lock);
5223 		}
5224 
5225 		new_sector = raid5_compute_sector(conf, logical_sector,
5226 						  previous,
5227 						  &dd_idx, NULL);
5228 		pr_debug("raid456: make_request, sector %llu logical %llu\n",
5229 			(unsigned long long)new_sector,
5230 			(unsigned long long)logical_sector);
5231 
5232 		sh = get_active_stripe(conf, new_sector, previous,
5233 				       (bi->bi_rw&RWA_MASK), 0);
5234 		if (sh) {
5235 			if (unlikely(previous)) {
5236 				/* expansion might have moved on while waiting for a
5237 				 * stripe, so we must do the range check again.
5238 				 * Expansion could still move past after this
5239 				 * test, but as we are holding a reference to
5240 				 * 'sh', we know that if that happens,
5241 				 *  STRIPE_EXPANDING will get set and the expansion
5242 				 * won't proceed until we finish with the stripe.
5243 				 */
5244 				int must_retry = 0;
5245 				spin_lock_irq(&conf->device_lock);
5246 				if (mddev->reshape_backwards
5247 				    ? logical_sector >= conf->reshape_progress
5248 				    : logical_sector < conf->reshape_progress)
5249 					/* mismatch, need to try again */
5250 					must_retry = 1;
5251 				spin_unlock_irq(&conf->device_lock);
5252 				if (must_retry) {
5253 					release_stripe(sh);
5254 					schedule();
5255 					do_prepare = true;
5256 					goto retry;
5257 				}
5258 			}
5259 			if (read_seqcount_retry(&conf->gen_lock, seq)) {
5260 				/* Might have got the wrong stripe_head
5261 				 * by accident
5262 				 */
5263 				release_stripe(sh);
5264 				goto retry;
5265 			}
5266 
5267 			if (rw == WRITE &&
5268 			    logical_sector >= mddev->suspend_lo &&
5269 			    logical_sector < mddev->suspend_hi) {
5270 				release_stripe(sh);
5271 				/* As the suspend_* range is controlled by
5272 				 * userspace, we want an interruptible
5273 				 * wait.
5274 				 */
5275 				flush_signals(current);
5276 				prepare_to_wait(&conf->wait_for_overlap,
5277 						&w, TASK_INTERRUPTIBLE);
5278 				if (logical_sector >= mddev->suspend_lo &&
5279 				    logical_sector < mddev->suspend_hi) {
5280 					schedule();
5281 					do_prepare = true;
5282 				}
5283 				goto retry;
5284 			}
5285 
5286 			if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5287 			    !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5288 				/* Stripe is busy expanding or
5289 				 * add failed due to overlap.  Flush everything
5290 				 * and wait a while
5291 				 */
5292 				md_wakeup_thread(mddev->thread);
5293 				release_stripe(sh);
5294 				schedule();
5295 				do_prepare = true;
5296 				goto retry;
5297 			}
5298 			set_bit(STRIPE_HANDLE, &sh->state);
5299 			clear_bit(STRIPE_DELAYED, &sh->state);
5300 			if ((!sh->batch_head || sh == sh->batch_head) &&
5301 			    (bi->bi_rw & REQ_SYNC) &&
5302 			    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5303 				atomic_inc(&conf->preread_active_stripes);
5304 			release_stripe_plug(mddev, sh);
5305 		} else {
5306 			/* cannot get stripe for read-ahead, just give-up */
5307 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
5308 			break;
5309 		}
5310 	}
5311 	finish_wait(&conf->wait_for_overlap, &w);
5312 
5313 	remaining = raid5_dec_bi_active_stripes(bi);
5314 	if (remaining == 0) {
5315 
5316 		if ( rw == WRITE )
5317 			md_write_end(mddev);
5318 
5319 		trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
5320 					 bi, 0);
5321 		bio_endio(bi, 0);
5322 	}
5323 }
5324 
5325 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5326 
5327 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5328 {
5329 	/* reshaping is quite different to recovery/resync so it is
5330 	 * handled quite separately ... here.
5331 	 *
5332 	 * On each call to sync_request, we gather one chunk worth of
5333 	 * destination stripes and flag them as expanding.
5334 	 * Then we find all the source stripes and request reads.
5335 	 * As the reads complete, handle_stripe will copy the data
5336 	 * into the destination stripe and release that stripe.
5337 	 */
5338 	struct r5conf *conf = mddev->private;
5339 	struct stripe_head *sh;
5340 	sector_t first_sector, last_sector;
5341 	int raid_disks = conf->previous_raid_disks;
5342 	int data_disks = raid_disks - conf->max_degraded;
5343 	int new_data_disks = conf->raid_disks - conf->max_degraded;
5344 	int i;
5345 	int dd_idx;
5346 	sector_t writepos, readpos, safepos;
5347 	sector_t stripe_addr;
5348 	int reshape_sectors;
5349 	struct list_head stripes;
5350 
5351 	if (sector_nr == 0) {
5352 		/* If restarting in the middle, skip the initial sectors */
5353 		if (mddev->reshape_backwards &&
5354 		    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5355 			sector_nr = raid5_size(mddev, 0, 0)
5356 				- conf->reshape_progress;
5357 		} else if (!mddev->reshape_backwards &&
5358 			   conf->reshape_progress > 0)
5359 			sector_nr = conf->reshape_progress;
5360 		sector_div(sector_nr, new_data_disks);
5361 		if (sector_nr) {
5362 			mddev->curr_resync_completed = sector_nr;
5363 			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5364 			*skipped = 1;
5365 			return sector_nr;
5366 		}
5367 	}
5368 
5369 	/* We need to process a full chunk at a time.
5370 	 * If old and new chunk sizes differ, we need to process the
5371 	 * largest of these
5372 	 */
5373 	if (mddev->new_chunk_sectors > mddev->chunk_sectors)
5374 		reshape_sectors = mddev->new_chunk_sectors;
5375 	else
5376 		reshape_sectors = mddev->chunk_sectors;
5377 
5378 	/* We update the metadata at least every 10 seconds, or when
5379 	 * the data about to be copied would over-write the source of
5380 	 * the data at the front of the range.  i.e. one new_stripe
5381 	 * along from reshape_progress new_maps to after where
5382 	 * reshape_safe old_maps to
5383 	 */
5384 	writepos = conf->reshape_progress;
5385 	sector_div(writepos, new_data_disks);
5386 	readpos = conf->reshape_progress;
5387 	sector_div(readpos, data_disks);
5388 	safepos = conf->reshape_safe;
5389 	sector_div(safepos, data_disks);
5390 	if (mddev->reshape_backwards) {
5391 		writepos -= min_t(sector_t, reshape_sectors, writepos);
5392 		readpos += reshape_sectors;
5393 		safepos += reshape_sectors;
5394 	} else {
5395 		writepos += reshape_sectors;
5396 		readpos -= min_t(sector_t, reshape_sectors, readpos);
5397 		safepos -= min_t(sector_t, reshape_sectors, safepos);
5398 	}
5399 
5400 	/* Having calculated the 'writepos' possibly use it
5401 	 * to set 'stripe_addr' which is where we will write to.
5402 	 */
5403 	if (mddev->reshape_backwards) {
5404 		BUG_ON(conf->reshape_progress == 0);
5405 		stripe_addr = writepos;
5406 		BUG_ON((mddev->dev_sectors &
5407 			~((sector_t)reshape_sectors - 1))
5408 		       - reshape_sectors - stripe_addr
5409 		       != sector_nr);
5410 	} else {
5411 		BUG_ON(writepos != sector_nr + reshape_sectors);
5412 		stripe_addr = sector_nr;
5413 	}
5414 
5415 	/* 'writepos' is the most advanced device address we might write.
5416 	 * 'readpos' is the least advanced device address we might read.
5417 	 * 'safepos' is the least address recorded in the metadata as having
5418 	 *     been reshaped.
5419 	 * If there is a min_offset_diff, these are adjusted either by
5420 	 * increasing the safepos/readpos if diff is negative, or
5421 	 * increasing writepos if diff is positive.
5422 	 * If 'readpos' is then behind 'writepos', there is no way that we can
5423 	 * ensure safety in the face of a crash - that must be done by userspace
5424 	 * making a backup of the data.  So in that case there is no particular
5425 	 * rush to update metadata.
5426 	 * Otherwise if 'safepos' is behind 'writepos', then we really need to
5427 	 * update the metadata to advance 'safepos' to match 'readpos' so that
5428 	 * we can be safe in the event of a crash.
5429 	 * So we insist on updating metadata if safepos is behind writepos and
5430 	 * readpos is beyond writepos.
5431 	 * In any case, update the metadata every 10 seconds.
5432 	 * Maybe that number should be configurable, but I'm not sure it is
5433 	 * worth it.... maybe it could be a multiple of safemode_delay???
5434 	 */
5435 	if (conf->min_offset_diff < 0) {
5436 		safepos += -conf->min_offset_diff;
5437 		readpos += -conf->min_offset_diff;
5438 	} else
5439 		writepos += conf->min_offset_diff;
5440 
5441 	if ((mddev->reshape_backwards
5442 	     ? (safepos > writepos && readpos < writepos)
5443 	     : (safepos < writepos && readpos > writepos)) ||
5444 	    time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5445 		/* Cannot proceed until we've updated the superblock... */
5446 		wait_event(conf->wait_for_overlap,
5447 			   atomic_read(&conf->reshape_stripes)==0
5448 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5449 		if (atomic_read(&conf->reshape_stripes) != 0)
5450 			return 0;
5451 		mddev->reshape_position = conf->reshape_progress;
5452 		mddev->curr_resync_completed = sector_nr;
5453 		conf->reshape_checkpoint = jiffies;
5454 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
5455 		md_wakeup_thread(mddev->thread);
5456 		wait_event(mddev->sb_wait, mddev->flags == 0 ||
5457 			   test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5458 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5459 			return 0;
5460 		spin_lock_irq(&conf->device_lock);
5461 		conf->reshape_safe = mddev->reshape_position;
5462 		spin_unlock_irq(&conf->device_lock);
5463 		wake_up(&conf->wait_for_overlap);
5464 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5465 	}
5466 
5467 	INIT_LIST_HEAD(&stripes);
5468 	for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5469 		int j;
5470 		int skipped_disk = 0;
5471 		sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5472 		set_bit(STRIPE_EXPANDING, &sh->state);
5473 		atomic_inc(&conf->reshape_stripes);
5474 		/* If any of this stripe is beyond the end of the old
5475 		 * array, then we need to zero those blocks
5476 		 */
5477 		for (j=sh->disks; j--;) {
5478 			sector_t s;
5479 			if (j == sh->pd_idx)
5480 				continue;
5481 			if (conf->level == 6 &&
5482 			    j == sh->qd_idx)
5483 				continue;
5484 			s = compute_blocknr(sh, j, 0);
5485 			if (s < raid5_size(mddev, 0, 0)) {
5486 				skipped_disk = 1;
5487 				continue;
5488 			}
5489 			memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5490 			set_bit(R5_Expanded, &sh->dev[j].flags);
5491 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
5492 		}
5493 		if (!skipped_disk) {
5494 			set_bit(STRIPE_EXPAND_READY, &sh->state);
5495 			set_bit(STRIPE_HANDLE, &sh->state);
5496 		}
5497 		list_add(&sh->lru, &stripes);
5498 	}
5499 	spin_lock_irq(&conf->device_lock);
5500 	if (mddev->reshape_backwards)
5501 		conf->reshape_progress -= reshape_sectors * new_data_disks;
5502 	else
5503 		conf->reshape_progress += reshape_sectors * new_data_disks;
5504 	spin_unlock_irq(&conf->device_lock);
5505 	/* Ok, those stripe are ready. We can start scheduling
5506 	 * reads on the source stripes.
5507 	 * The source stripes are determined by mapping the first and last
5508 	 * block on the destination stripes.
5509 	 */
5510 	first_sector =
5511 		raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5512 				     1, &dd_idx, NULL);
5513 	last_sector =
5514 		raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5515 					    * new_data_disks - 1),
5516 				     1, &dd_idx, NULL);
5517 	if (last_sector >= mddev->dev_sectors)
5518 		last_sector = mddev->dev_sectors - 1;
5519 	while (first_sector <= last_sector) {
5520 		sh = get_active_stripe(conf, first_sector, 1, 0, 1);
5521 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5522 		set_bit(STRIPE_HANDLE, &sh->state);
5523 		release_stripe(sh);
5524 		first_sector += STRIPE_SECTORS;
5525 	}
5526 	/* Now that the sources are clearly marked, we can release
5527 	 * the destination stripes
5528 	 */
5529 	while (!list_empty(&stripes)) {
5530 		sh = list_entry(stripes.next, struct stripe_head, lru);
5531 		list_del_init(&sh->lru);
5532 		release_stripe(sh);
5533 	}
5534 	/* If this takes us to the resync_max point where we have to pause,
5535 	 * then we need to write out the superblock.
5536 	 */
5537 	sector_nr += reshape_sectors;
5538 	if ((sector_nr - mddev->curr_resync_completed) * 2
5539 	    >= mddev->resync_max - mddev->curr_resync_completed) {
5540 		/* Cannot proceed until we've updated the superblock... */
5541 		wait_event(conf->wait_for_overlap,
5542 			   atomic_read(&conf->reshape_stripes) == 0
5543 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5544 		if (atomic_read(&conf->reshape_stripes) != 0)
5545 			goto ret;
5546 		mddev->reshape_position = conf->reshape_progress;
5547 		mddev->curr_resync_completed = sector_nr;
5548 		conf->reshape_checkpoint = jiffies;
5549 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
5550 		md_wakeup_thread(mddev->thread);
5551 		wait_event(mddev->sb_wait,
5552 			   !test_bit(MD_CHANGE_DEVS, &mddev->flags)
5553 			   || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5554 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5555 			goto ret;
5556 		spin_lock_irq(&conf->device_lock);
5557 		conf->reshape_safe = mddev->reshape_position;
5558 		spin_unlock_irq(&conf->device_lock);
5559 		wake_up(&conf->wait_for_overlap);
5560 		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5561 	}
5562 ret:
5563 	return reshape_sectors;
5564 }
5565 
5566 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5567 {
5568 	struct r5conf *conf = mddev->private;
5569 	struct stripe_head *sh;
5570 	sector_t max_sector = mddev->dev_sectors;
5571 	sector_t sync_blocks;
5572 	int still_degraded = 0;
5573 	int i;
5574 
5575 	if (sector_nr >= max_sector) {
5576 		/* just being told to finish up .. nothing much to do */
5577 
5578 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5579 			end_reshape(conf);
5580 			return 0;
5581 		}
5582 
5583 		if (mddev->curr_resync < max_sector) /* aborted */
5584 			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5585 					&sync_blocks, 1);
5586 		else /* completed sync */
5587 			conf->fullsync = 0;
5588 		bitmap_close_sync(mddev->bitmap);
5589 
5590 		return 0;
5591 	}
5592 
5593 	/* Allow raid5_quiesce to complete */
5594 	wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5595 
5596 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5597 		return reshape_request(mddev, sector_nr, skipped);
5598 
5599 	/* No need to check resync_max as we never do more than one
5600 	 * stripe, and as resync_max will always be on a chunk boundary,
5601 	 * if the check in md_do_sync didn't fire, there is no chance
5602 	 * of overstepping resync_max here
5603 	 */
5604 
5605 	/* if there is too many failed drives and we are trying
5606 	 * to resync, then assert that we are finished, because there is
5607 	 * nothing we can do.
5608 	 */
5609 	if (mddev->degraded >= conf->max_degraded &&
5610 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5611 		sector_t rv = mddev->dev_sectors - sector_nr;
5612 		*skipped = 1;
5613 		return rv;
5614 	}
5615 	if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5616 	    !conf->fullsync &&
5617 	    !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5618 	    sync_blocks >= STRIPE_SECTORS) {
5619 		/* we can skip this block, and probably more */
5620 		sync_blocks /= STRIPE_SECTORS;
5621 		*skipped = 1;
5622 		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5623 	}
5624 
5625 	bitmap_cond_end_sync(mddev->bitmap, sector_nr);
5626 
5627 	sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
5628 	if (sh == NULL) {
5629 		sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
5630 		/* make sure we don't swamp the stripe cache if someone else
5631 		 * is trying to get access
5632 		 */
5633 		schedule_timeout_uninterruptible(1);
5634 	}
5635 	/* Need to check if array will still be degraded after recovery/resync
5636 	 * Note in case of > 1 drive failures it's possible we're rebuilding
5637 	 * one drive while leaving another faulty drive in array.
5638 	 */
5639 	rcu_read_lock();
5640 	for (i = 0; i < conf->raid_disks; i++) {
5641 		struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
5642 
5643 		if (rdev == NULL || test_bit(Faulty, &rdev->flags))
5644 			still_degraded = 1;
5645 	}
5646 	rcu_read_unlock();
5647 
5648 	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5649 
5650 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5651 	set_bit(STRIPE_HANDLE, &sh->state);
5652 
5653 	release_stripe(sh);
5654 
5655 	return STRIPE_SECTORS;
5656 }
5657 
5658 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5659 {
5660 	/* We may not be able to submit a whole bio at once as there
5661 	 * may not be enough stripe_heads available.
5662 	 * We cannot pre-allocate enough stripe_heads as we may need
5663 	 * more than exist in the cache (if we allow ever large chunks).
5664 	 * So we do one stripe head at a time and record in
5665 	 * ->bi_hw_segments how many have been done.
5666 	 *
5667 	 * We *know* that this entire raid_bio is in one chunk, so
5668 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5669 	 */
5670 	struct stripe_head *sh;
5671 	int dd_idx;
5672 	sector_t sector, logical_sector, last_sector;
5673 	int scnt = 0;
5674 	int remaining;
5675 	int handled = 0;
5676 
5677 	logical_sector = raid_bio->bi_iter.bi_sector &
5678 		~((sector_t)STRIPE_SECTORS-1);
5679 	sector = raid5_compute_sector(conf, logical_sector,
5680 				      0, &dd_idx, NULL);
5681 	last_sector = bio_end_sector(raid_bio);
5682 
5683 	for (; logical_sector < last_sector;
5684 	     logical_sector += STRIPE_SECTORS,
5685 		     sector += STRIPE_SECTORS,
5686 		     scnt++) {
5687 
5688 		if (scnt < raid5_bi_processed_stripes(raid_bio))
5689 			/* already done this stripe */
5690 			continue;
5691 
5692 		sh = get_active_stripe(conf, sector, 0, 1, 1);
5693 
5694 		if (!sh) {
5695 			/* failed to get a stripe - must wait */
5696 			raid5_set_bi_processed_stripes(raid_bio, scnt);
5697 			conf->retry_read_aligned = raid_bio;
5698 			return handled;
5699 		}
5700 
5701 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
5702 			release_stripe(sh);
5703 			raid5_set_bi_processed_stripes(raid_bio, scnt);
5704 			conf->retry_read_aligned = raid_bio;
5705 			return handled;
5706 		}
5707 
5708 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
5709 		handle_stripe(sh);
5710 		release_stripe(sh);
5711 		handled++;
5712 	}
5713 	remaining = raid5_dec_bi_active_stripes(raid_bio);
5714 	if (remaining == 0) {
5715 		trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
5716 					 raid_bio, 0);
5717 		bio_endio(raid_bio, 0);
5718 	}
5719 	if (atomic_dec_and_test(&conf->active_aligned_reads))
5720 		wake_up(&conf->wait_for_quiescent);
5721 	return handled;
5722 }
5723 
5724 static int handle_active_stripes(struct r5conf *conf, int group,
5725 				 struct r5worker *worker,
5726 				 struct list_head *temp_inactive_list)
5727 {
5728 	struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
5729 	int i, batch_size = 0, hash;
5730 	bool release_inactive = false;
5731 
5732 	while (batch_size < MAX_STRIPE_BATCH &&
5733 			(sh = __get_priority_stripe(conf, group)) != NULL)
5734 		batch[batch_size++] = sh;
5735 
5736 	if (batch_size == 0) {
5737 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5738 			if (!list_empty(temp_inactive_list + i))
5739 				break;
5740 		if (i == NR_STRIPE_HASH_LOCKS)
5741 			return batch_size;
5742 		release_inactive = true;
5743 	}
5744 	spin_unlock_irq(&conf->device_lock);
5745 
5746 	release_inactive_stripe_list(conf, temp_inactive_list,
5747 				     NR_STRIPE_HASH_LOCKS);
5748 
5749 	if (release_inactive) {
5750 		spin_lock_irq(&conf->device_lock);
5751 		return 0;
5752 	}
5753 
5754 	for (i = 0; i < batch_size; i++)
5755 		handle_stripe(batch[i]);
5756 
5757 	cond_resched();
5758 
5759 	spin_lock_irq(&conf->device_lock);
5760 	for (i = 0; i < batch_size; i++) {
5761 		hash = batch[i]->hash_lock_index;
5762 		__release_stripe(conf, batch[i], &temp_inactive_list[hash]);
5763 	}
5764 	return batch_size;
5765 }
5766 
5767 static void raid5_do_work(struct work_struct *work)
5768 {
5769 	struct r5worker *worker = container_of(work, struct r5worker, work);
5770 	struct r5worker_group *group = worker->group;
5771 	struct r5conf *conf = group->conf;
5772 	int group_id = group - conf->worker_groups;
5773 	int handled;
5774 	struct blk_plug plug;
5775 
5776 	pr_debug("+++ raid5worker active\n");
5777 
5778 	blk_start_plug(&plug);
5779 	handled = 0;
5780 	spin_lock_irq(&conf->device_lock);
5781 	while (1) {
5782 		int batch_size, released;
5783 
5784 		released = release_stripe_list(conf, worker->temp_inactive_list);
5785 
5786 		batch_size = handle_active_stripes(conf, group_id, worker,
5787 						   worker->temp_inactive_list);
5788 		worker->working = false;
5789 		if (!batch_size && !released)
5790 			break;
5791 		handled += batch_size;
5792 	}
5793 	pr_debug("%d stripes handled\n", handled);
5794 
5795 	spin_unlock_irq(&conf->device_lock);
5796 	blk_finish_plug(&plug);
5797 
5798 	pr_debug("--- raid5worker inactive\n");
5799 }
5800 
5801 /*
5802  * This is our raid5 kernel thread.
5803  *
5804  * We scan the hash table for stripes which can be handled now.
5805  * During the scan, completed stripes are saved for us by the interrupt
5806  * handler, so that they will not have to wait for our next wakeup.
5807  */
5808 static void raid5d(struct md_thread *thread)
5809 {
5810 	struct mddev *mddev = thread->mddev;
5811 	struct r5conf *conf = mddev->private;
5812 	int handled;
5813 	struct blk_plug plug;
5814 
5815 	pr_debug("+++ raid5d active\n");
5816 
5817 	md_check_recovery(mddev);
5818 
5819 	blk_start_plug(&plug);
5820 	handled = 0;
5821 	spin_lock_irq(&conf->device_lock);
5822 	while (1) {
5823 		struct bio *bio;
5824 		int batch_size, released;
5825 
5826 		released = release_stripe_list(conf, conf->temp_inactive_list);
5827 		if (released)
5828 			clear_bit(R5_DID_ALLOC, &conf->cache_state);
5829 
5830 		if (
5831 		    !list_empty(&conf->bitmap_list)) {
5832 			/* Now is a good time to flush some bitmap updates */
5833 			conf->seq_flush++;
5834 			spin_unlock_irq(&conf->device_lock);
5835 			bitmap_unplug(mddev->bitmap);
5836 			spin_lock_irq(&conf->device_lock);
5837 			conf->seq_write = conf->seq_flush;
5838 			activate_bit_delay(conf, conf->temp_inactive_list);
5839 		}
5840 		raid5_activate_delayed(conf);
5841 
5842 		while ((bio = remove_bio_from_retry(conf))) {
5843 			int ok;
5844 			spin_unlock_irq(&conf->device_lock);
5845 			ok = retry_aligned_read(conf, bio);
5846 			spin_lock_irq(&conf->device_lock);
5847 			if (!ok)
5848 				break;
5849 			handled++;
5850 		}
5851 
5852 		batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
5853 						   conf->temp_inactive_list);
5854 		if (!batch_size && !released)
5855 			break;
5856 		handled += batch_size;
5857 
5858 		if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
5859 			spin_unlock_irq(&conf->device_lock);
5860 			md_check_recovery(mddev);
5861 			spin_lock_irq(&conf->device_lock);
5862 		}
5863 	}
5864 	pr_debug("%d stripes handled\n", handled);
5865 
5866 	spin_unlock_irq(&conf->device_lock);
5867 	if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
5868 	    mutex_trylock(&conf->cache_size_mutex)) {
5869 		grow_one_stripe(conf, __GFP_NOWARN);
5870 		/* Set flag even if allocation failed.  This helps
5871 		 * slow down allocation requests when mem is short
5872 		 */
5873 		set_bit(R5_DID_ALLOC, &conf->cache_state);
5874 		mutex_unlock(&conf->cache_size_mutex);
5875 	}
5876 
5877 	async_tx_issue_pending_all();
5878 	blk_finish_plug(&plug);
5879 
5880 	pr_debug("--- raid5d inactive\n");
5881 }
5882 
5883 static ssize_t
5884 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
5885 {
5886 	struct r5conf *conf;
5887 	int ret = 0;
5888 	spin_lock(&mddev->lock);
5889 	conf = mddev->private;
5890 	if (conf)
5891 		ret = sprintf(page, "%d\n", conf->min_nr_stripes);
5892 	spin_unlock(&mddev->lock);
5893 	return ret;
5894 }
5895 
5896 int
5897 raid5_set_cache_size(struct mddev *mddev, int size)
5898 {
5899 	struct r5conf *conf = mddev->private;
5900 	int err;
5901 
5902 	if (size <= 16 || size > 32768)
5903 		return -EINVAL;
5904 
5905 	conf->min_nr_stripes = size;
5906 	mutex_lock(&conf->cache_size_mutex);
5907 	while (size < conf->max_nr_stripes &&
5908 	       drop_one_stripe(conf))
5909 		;
5910 	mutex_unlock(&conf->cache_size_mutex);
5911 
5912 
5913 	err = md_allow_write(mddev);
5914 	if (err)
5915 		return err;
5916 
5917 	mutex_lock(&conf->cache_size_mutex);
5918 	while (size > conf->max_nr_stripes)
5919 		if (!grow_one_stripe(conf, GFP_KERNEL))
5920 			break;
5921 	mutex_unlock(&conf->cache_size_mutex);
5922 
5923 	return 0;
5924 }
5925 EXPORT_SYMBOL(raid5_set_cache_size);
5926 
5927 static ssize_t
5928 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
5929 {
5930 	struct r5conf *conf;
5931 	unsigned long new;
5932 	int err;
5933 
5934 	if (len >= PAGE_SIZE)
5935 		return -EINVAL;
5936 	if (kstrtoul(page, 10, &new))
5937 		return -EINVAL;
5938 	err = mddev_lock(mddev);
5939 	if (err)
5940 		return err;
5941 	conf = mddev->private;
5942 	if (!conf)
5943 		err = -ENODEV;
5944 	else
5945 		err = raid5_set_cache_size(mddev, new);
5946 	mddev_unlock(mddev);
5947 
5948 	return err ?: len;
5949 }
5950 
5951 static struct md_sysfs_entry
5952 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
5953 				raid5_show_stripe_cache_size,
5954 				raid5_store_stripe_cache_size);
5955 
5956 static ssize_t
5957 raid5_show_rmw_level(struct mddev  *mddev, char *page)
5958 {
5959 	struct r5conf *conf = mddev->private;
5960 	if (conf)
5961 		return sprintf(page, "%d\n", conf->rmw_level);
5962 	else
5963 		return 0;
5964 }
5965 
5966 static ssize_t
5967 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
5968 {
5969 	struct r5conf *conf = mddev->private;
5970 	unsigned long new;
5971 
5972 	if (!conf)
5973 		return -ENODEV;
5974 
5975 	if (len >= PAGE_SIZE)
5976 		return -EINVAL;
5977 
5978 	if (kstrtoul(page, 10, &new))
5979 		return -EINVAL;
5980 
5981 	if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
5982 		return -EINVAL;
5983 
5984 	if (new != PARITY_DISABLE_RMW &&
5985 	    new != PARITY_ENABLE_RMW &&
5986 	    new != PARITY_PREFER_RMW)
5987 		return -EINVAL;
5988 
5989 	conf->rmw_level = new;
5990 	return len;
5991 }
5992 
5993 static struct md_sysfs_entry
5994 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
5995 			 raid5_show_rmw_level,
5996 			 raid5_store_rmw_level);
5997 
5998 
5999 static ssize_t
6000 raid5_show_preread_threshold(struct mddev *mddev, char *page)
6001 {
6002 	struct r5conf *conf;
6003 	int ret = 0;
6004 	spin_lock(&mddev->lock);
6005 	conf = mddev->private;
6006 	if (conf)
6007 		ret = sprintf(page, "%d\n", conf->bypass_threshold);
6008 	spin_unlock(&mddev->lock);
6009 	return ret;
6010 }
6011 
6012 static ssize_t
6013 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
6014 {
6015 	struct r5conf *conf;
6016 	unsigned long new;
6017 	int err;
6018 
6019 	if (len >= PAGE_SIZE)
6020 		return -EINVAL;
6021 	if (kstrtoul(page, 10, &new))
6022 		return -EINVAL;
6023 
6024 	err = mddev_lock(mddev);
6025 	if (err)
6026 		return err;
6027 	conf = mddev->private;
6028 	if (!conf)
6029 		err = -ENODEV;
6030 	else if (new > conf->min_nr_stripes)
6031 		err = -EINVAL;
6032 	else
6033 		conf->bypass_threshold = new;
6034 	mddev_unlock(mddev);
6035 	return err ?: len;
6036 }
6037 
6038 static struct md_sysfs_entry
6039 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6040 					S_IRUGO | S_IWUSR,
6041 					raid5_show_preread_threshold,
6042 					raid5_store_preread_threshold);
6043 
6044 static ssize_t
6045 raid5_show_skip_copy(struct mddev *mddev, char *page)
6046 {
6047 	struct r5conf *conf;
6048 	int ret = 0;
6049 	spin_lock(&mddev->lock);
6050 	conf = mddev->private;
6051 	if (conf)
6052 		ret = sprintf(page, "%d\n", conf->skip_copy);
6053 	spin_unlock(&mddev->lock);
6054 	return ret;
6055 }
6056 
6057 static ssize_t
6058 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6059 {
6060 	struct r5conf *conf;
6061 	unsigned long new;
6062 	int err;
6063 
6064 	if (len >= PAGE_SIZE)
6065 		return -EINVAL;
6066 	if (kstrtoul(page, 10, &new))
6067 		return -EINVAL;
6068 	new = !!new;
6069 
6070 	err = mddev_lock(mddev);
6071 	if (err)
6072 		return err;
6073 	conf = mddev->private;
6074 	if (!conf)
6075 		err = -ENODEV;
6076 	else if (new != conf->skip_copy) {
6077 		mddev_suspend(mddev);
6078 		conf->skip_copy = new;
6079 		if (new)
6080 			mddev->queue->backing_dev_info.capabilities |=
6081 				BDI_CAP_STABLE_WRITES;
6082 		else
6083 			mddev->queue->backing_dev_info.capabilities &=
6084 				~BDI_CAP_STABLE_WRITES;
6085 		mddev_resume(mddev);
6086 	}
6087 	mddev_unlock(mddev);
6088 	return err ?: len;
6089 }
6090 
6091 static struct md_sysfs_entry
6092 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6093 					raid5_show_skip_copy,
6094 					raid5_store_skip_copy);
6095 
6096 static ssize_t
6097 stripe_cache_active_show(struct mddev *mddev, char *page)
6098 {
6099 	struct r5conf *conf = mddev->private;
6100 	if (conf)
6101 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6102 	else
6103 		return 0;
6104 }
6105 
6106 static struct md_sysfs_entry
6107 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6108 
6109 static ssize_t
6110 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6111 {
6112 	struct r5conf *conf;
6113 	int ret = 0;
6114 	spin_lock(&mddev->lock);
6115 	conf = mddev->private;
6116 	if (conf)
6117 		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6118 	spin_unlock(&mddev->lock);
6119 	return ret;
6120 }
6121 
6122 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6123 			       int *group_cnt,
6124 			       int *worker_cnt_per_group,
6125 			       struct r5worker_group **worker_groups);
6126 static ssize_t
6127 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6128 {
6129 	struct r5conf *conf;
6130 	unsigned long new;
6131 	int err;
6132 	struct r5worker_group *new_groups, *old_groups;
6133 	int group_cnt, worker_cnt_per_group;
6134 
6135 	if (len >= PAGE_SIZE)
6136 		return -EINVAL;
6137 	if (kstrtoul(page, 10, &new))
6138 		return -EINVAL;
6139 
6140 	err = mddev_lock(mddev);
6141 	if (err)
6142 		return err;
6143 	conf = mddev->private;
6144 	if (!conf)
6145 		err = -ENODEV;
6146 	else if (new != conf->worker_cnt_per_group) {
6147 		mddev_suspend(mddev);
6148 
6149 		old_groups = conf->worker_groups;
6150 		if (old_groups)
6151 			flush_workqueue(raid5_wq);
6152 
6153 		err = alloc_thread_groups(conf, new,
6154 					  &group_cnt, &worker_cnt_per_group,
6155 					  &new_groups);
6156 		if (!err) {
6157 			spin_lock_irq(&conf->device_lock);
6158 			conf->group_cnt = group_cnt;
6159 			conf->worker_cnt_per_group = worker_cnt_per_group;
6160 			conf->worker_groups = new_groups;
6161 			spin_unlock_irq(&conf->device_lock);
6162 
6163 			if (old_groups)
6164 				kfree(old_groups[0].workers);
6165 			kfree(old_groups);
6166 		}
6167 		mddev_resume(mddev);
6168 	}
6169 	mddev_unlock(mddev);
6170 
6171 	return err ?: len;
6172 }
6173 
6174 static struct md_sysfs_entry
6175 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6176 				raid5_show_group_thread_cnt,
6177 				raid5_store_group_thread_cnt);
6178 
6179 static struct attribute *raid5_attrs[] =  {
6180 	&raid5_stripecache_size.attr,
6181 	&raid5_stripecache_active.attr,
6182 	&raid5_preread_bypass_threshold.attr,
6183 	&raid5_group_thread_cnt.attr,
6184 	&raid5_skip_copy.attr,
6185 	&raid5_rmw_level.attr,
6186 	NULL,
6187 };
6188 static struct attribute_group raid5_attrs_group = {
6189 	.name = NULL,
6190 	.attrs = raid5_attrs,
6191 };
6192 
6193 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6194 			       int *group_cnt,
6195 			       int *worker_cnt_per_group,
6196 			       struct r5worker_group **worker_groups)
6197 {
6198 	int i, j, k;
6199 	ssize_t size;
6200 	struct r5worker *workers;
6201 
6202 	*worker_cnt_per_group = cnt;
6203 	if (cnt == 0) {
6204 		*group_cnt = 0;
6205 		*worker_groups = NULL;
6206 		return 0;
6207 	}
6208 	*group_cnt = num_possible_nodes();
6209 	size = sizeof(struct r5worker) * cnt;
6210 	workers = kzalloc(size * *group_cnt, GFP_NOIO);
6211 	*worker_groups = kzalloc(sizeof(struct r5worker_group) *
6212 				*group_cnt, GFP_NOIO);
6213 	if (!*worker_groups || !workers) {
6214 		kfree(workers);
6215 		kfree(*worker_groups);
6216 		return -ENOMEM;
6217 	}
6218 
6219 	for (i = 0; i < *group_cnt; i++) {
6220 		struct r5worker_group *group;
6221 
6222 		group = &(*worker_groups)[i];
6223 		INIT_LIST_HEAD(&group->handle_list);
6224 		group->conf = conf;
6225 		group->workers = workers + i * cnt;
6226 
6227 		for (j = 0; j < cnt; j++) {
6228 			struct r5worker *worker = group->workers + j;
6229 			worker->group = group;
6230 			INIT_WORK(&worker->work, raid5_do_work);
6231 
6232 			for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6233 				INIT_LIST_HEAD(worker->temp_inactive_list + k);
6234 		}
6235 	}
6236 
6237 	return 0;
6238 }
6239 
6240 static void free_thread_groups(struct r5conf *conf)
6241 {
6242 	if (conf->worker_groups)
6243 		kfree(conf->worker_groups[0].workers);
6244 	kfree(conf->worker_groups);
6245 	conf->worker_groups = NULL;
6246 }
6247 
6248 static sector_t
6249 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6250 {
6251 	struct r5conf *conf = mddev->private;
6252 
6253 	if (!sectors)
6254 		sectors = mddev->dev_sectors;
6255 	if (!raid_disks)
6256 		/* size is defined by the smallest of previous and new size */
6257 		raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6258 
6259 	sectors &= ~((sector_t)mddev->chunk_sectors - 1);
6260 	sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
6261 	return sectors * (raid_disks - conf->max_degraded);
6262 }
6263 
6264 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6265 {
6266 	safe_put_page(percpu->spare_page);
6267 	if (percpu->scribble)
6268 		flex_array_free(percpu->scribble);
6269 	percpu->spare_page = NULL;
6270 	percpu->scribble = NULL;
6271 }
6272 
6273 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6274 {
6275 	if (conf->level == 6 && !percpu->spare_page)
6276 		percpu->spare_page = alloc_page(GFP_KERNEL);
6277 	if (!percpu->scribble)
6278 		percpu->scribble = scribble_alloc(max(conf->raid_disks,
6279 						      conf->previous_raid_disks),
6280 						  max(conf->chunk_sectors,
6281 						      conf->prev_chunk_sectors)
6282 						   / STRIPE_SECTORS,
6283 						  GFP_KERNEL);
6284 
6285 	if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6286 		free_scratch_buffer(conf, percpu);
6287 		return -ENOMEM;
6288 	}
6289 
6290 	return 0;
6291 }
6292 
6293 static void raid5_free_percpu(struct r5conf *conf)
6294 {
6295 	unsigned long cpu;
6296 
6297 	if (!conf->percpu)
6298 		return;
6299 
6300 #ifdef CONFIG_HOTPLUG_CPU
6301 	unregister_cpu_notifier(&conf->cpu_notify);
6302 #endif
6303 
6304 	get_online_cpus();
6305 	for_each_possible_cpu(cpu)
6306 		free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6307 	put_online_cpus();
6308 
6309 	free_percpu(conf->percpu);
6310 }
6311 
6312 static void free_conf(struct r5conf *conf)
6313 {
6314 	if (conf->shrinker.seeks)
6315 		unregister_shrinker(&conf->shrinker);
6316 	free_thread_groups(conf);
6317 	shrink_stripes(conf);
6318 	raid5_free_percpu(conf);
6319 	kfree(conf->disks);
6320 	kfree(conf->stripe_hashtbl);
6321 	kfree(conf);
6322 }
6323 
6324 #ifdef CONFIG_HOTPLUG_CPU
6325 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
6326 			      void *hcpu)
6327 {
6328 	struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
6329 	long cpu = (long)hcpu;
6330 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6331 
6332 	switch (action) {
6333 	case CPU_UP_PREPARE:
6334 	case CPU_UP_PREPARE_FROZEN:
6335 		if (alloc_scratch_buffer(conf, percpu)) {
6336 			pr_err("%s: failed memory allocation for cpu%ld\n",
6337 			       __func__, cpu);
6338 			return notifier_from_errno(-ENOMEM);
6339 		}
6340 		break;
6341 	case CPU_DEAD:
6342 	case CPU_DEAD_FROZEN:
6343 		free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6344 		break;
6345 	default:
6346 		break;
6347 	}
6348 	return NOTIFY_OK;
6349 }
6350 #endif
6351 
6352 static int raid5_alloc_percpu(struct r5conf *conf)
6353 {
6354 	unsigned long cpu;
6355 	int err = 0;
6356 
6357 	conf->percpu = alloc_percpu(struct raid5_percpu);
6358 	if (!conf->percpu)
6359 		return -ENOMEM;
6360 
6361 #ifdef CONFIG_HOTPLUG_CPU
6362 	conf->cpu_notify.notifier_call = raid456_cpu_notify;
6363 	conf->cpu_notify.priority = 0;
6364 	err = register_cpu_notifier(&conf->cpu_notify);
6365 	if (err)
6366 		return err;
6367 #endif
6368 
6369 	get_online_cpus();
6370 	for_each_present_cpu(cpu) {
6371 		err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6372 		if (err) {
6373 			pr_err("%s: failed memory allocation for cpu%ld\n",
6374 			       __func__, cpu);
6375 			break;
6376 		}
6377 	}
6378 	put_online_cpus();
6379 
6380 	return err;
6381 }
6382 
6383 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6384 				      struct shrink_control *sc)
6385 {
6386 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6387 	unsigned long ret = SHRINK_STOP;
6388 
6389 	if (mutex_trylock(&conf->cache_size_mutex)) {
6390 		ret= 0;
6391 		while (ret < sc->nr_to_scan &&
6392 		       conf->max_nr_stripes > conf->min_nr_stripes) {
6393 			if (drop_one_stripe(conf) == 0) {
6394 				ret = SHRINK_STOP;
6395 				break;
6396 			}
6397 			ret++;
6398 		}
6399 		mutex_unlock(&conf->cache_size_mutex);
6400 	}
6401 	return ret;
6402 }
6403 
6404 static unsigned long raid5_cache_count(struct shrinker *shrink,
6405 				       struct shrink_control *sc)
6406 {
6407 	struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6408 
6409 	if (conf->max_nr_stripes < conf->min_nr_stripes)
6410 		/* unlikely, but not impossible */
6411 		return 0;
6412 	return conf->max_nr_stripes - conf->min_nr_stripes;
6413 }
6414 
6415 static struct r5conf *setup_conf(struct mddev *mddev)
6416 {
6417 	struct r5conf *conf;
6418 	int raid_disk, memory, max_disks;
6419 	struct md_rdev *rdev;
6420 	struct disk_info *disk;
6421 	char pers_name[6];
6422 	int i;
6423 	int group_cnt, worker_cnt_per_group;
6424 	struct r5worker_group *new_group;
6425 
6426 	if (mddev->new_level != 5
6427 	    && mddev->new_level != 4
6428 	    && mddev->new_level != 6) {
6429 		printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6430 		       mdname(mddev), mddev->new_level);
6431 		return ERR_PTR(-EIO);
6432 	}
6433 	if ((mddev->new_level == 5
6434 	     && !algorithm_valid_raid5(mddev->new_layout)) ||
6435 	    (mddev->new_level == 6
6436 	     && !algorithm_valid_raid6(mddev->new_layout))) {
6437 		printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
6438 		       mdname(mddev), mddev->new_layout);
6439 		return ERR_PTR(-EIO);
6440 	}
6441 	if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6442 		printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6443 		       mdname(mddev), mddev->raid_disks);
6444 		return ERR_PTR(-EINVAL);
6445 	}
6446 
6447 	if (!mddev->new_chunk_sectors ||
6448 	    (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6449 	    !is_power_of_2(mddev->new_chunk_sectors)) {
6450 		printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
6451 		       mdname(mddev), mddev->new_chunk_sectors << 9);
6452 		return ERR_PTR(-EINVAL);
6453 	}
6454 
6455 	conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6456 	if (conf == NULL)
6457 		goto abort;
6458 	/* Don't enable multi-threading by default*/
6459 	if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6460 				 &new_group)) {
6461 		conf->group_cnt = group_cnt;
6462 		conf->worker_cnt_per_group = worker_cnt_per_group;
6463 		conf->worker_groups = new_group;
6464 	} else
6465 		goto abort;
6466 	spin_lock_init(&conf->device_lock);
6467 	seqcount_init(&conf->gen_lock);
6468 	mutex_init(&conf->cache_size_mutex);
6469 	init_waitqueue_head(&conf->wait_for_quiescent);
6470 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++) {
6471 		init_waitqueue_head(&conf->wait_for_stripe[i]);
6472 	}
6473 	init_waitqueue_head(&conf->wait_for_overlap);
6474 	INIT_LIST_HEAD(&conf->handle_list);
6475 	INIT_LIST_HEAD(&conf->hold_list);
6476 	INIT_LIST_HEAD(&conf->delayed_list);
6477 	INIT_LIST_HEAD(&conf->bitmap_list);
6478 	init_llist_head(&conf->released_stripes);
6479 	atomic_set(&conf->active_stripes, 0);
6480 	atomic_set(&conf->preread_active_stripes, 0);
6481 	atomic_set(&conf->active_aligned_reads, 0);
6482 	conf->bypass_threshold = BYPASS_THRESHOLD;
6483 	conf->recovery_disabled = mddev->recovery_disabled - 1;
6484 
6485 	conf->raid_disks = mddev->raid_disks;
6486 	if (mddev->reshape_position == MaxSector)
6487 		conf->previous_raid_disks = mddev->raid_disks;
6488 	else
6489 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6490 	max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6491 
6492 	conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6493 			      GFP_KERNEL);
6494 	if (!conf->disks)
6495 		goto abort;
6496 
6497 	conf->mddev = mddev;
6498 
6499 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6500 		goto abort;
6501 
6502 	/* We init hash_locks[0] separately to that it can be used
6503 	 * as the reference lock in the spin_lock_nest_lock() call
6504 	 * in lock_all_device_hash_locks_irq in order to convince
6505 	 * lockdep that we know what we are doing.
6506 	 */
6507 	spin_lock_init(conf->hash_locks);
6508 	for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6509 		spin_lock_init(conf->hash_locks + i);
6510 
6511 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6512 		INIT_LIST_HEAD(conf->inactive_list + i);
6513 
6514 	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6515 		INIT_LIST_HEAD(conf->temp_inactive_list + i);
6516 
6517 	conf->level = mddev->new_level;
6518 	conf->chunk_sectors = mddev->new_chunk_sectors;
6519 	if (raid5_alloc_percpu(conf) != 0)
6520 		goto abort;
6521 
6522 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6523 
6524 	rdev_for_each(rdev, mddev) {
6525 		raid_disk = rdev->raid_disk;
6526 		if (raid_disk >= max_disks
6527 		    || raid_disk < 0)
6528 			continue;
6529 		disk = conf->disks + raid_disk;
6530 
6531 		if (test_bit(Replacement, &rdev->flags)) {
6532 			if (disk->replacement)
6533 				goto abort;
6534 			disk->replacement = rdev;
6535 		} else {
6536 			if (disk->rdev)
6537 				goto abort;
6538 			disk->rdev = rdev;
6539 		}
6540 
6541 		if (test_bit(In_sync, &rdev->flags)) {
6542 			char b[BDEVNAME_SIZE];
6543 			printk(KERN_INFO "md/raid:%s: device %s operational as raid"
6544 			       " disk %d\n",
6545 			       mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
6546 		} else if (rdev->saved_raid_disk != raid_disk)
6547 			/* Cannot rely on bitmap to complete recovery */
6548 			conf->fullsync = 1;
6549 	}
6550 
6551 	conf->level = mddev->new_level;
6552 	if (conf->level == 6) {
6553 		conf->max_degraded = 2;
6554 		if (raid6_call.xor_syndrome)
6555 			conf->rmw_level = PARITY_ENABLE_RMW;
6556 		else
6557 			conf->rmw_level = PARITY_DISABLE_RMW;
6558 	} else {
6559 		conf->max_degraded = 1;
6560 		conf->rmw_level = PARITY_ENABLE_RMW;
6561 	}
6562 	conf->algorithm = mddev->new_layout;
6563 	conf->reshape_progress = mddev->reshape_position;
6564 	if (conf->reshape_progress != MaxSector) {
6565 		conf->prev_chunk_sectors = mddev->chunk_sectors;
6566 		conf->prev_algo = mddev->layout;
6567 	}
6568 
6569 	conf->min_nr_stripes = NR_STRIPES;
6570 	memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
6571 		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
6572 	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
6573 	if (grow_stripes(conf, conf->min_nr_stripes)) {
6574 		printk(KERN_ERR
6575 		       "md/raid:%s: couldn't allocate %dkB for buffers\n",
6576 		       mdname(mddev), memory);
6577 		goto abort;
6578 	} else
6579 		printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
6580 		       mdname(mddev), memory);
6581 	/*
6582 	 * Losing a stripe head costs more than the time to refill it,
6583 	 * it reduces the queue depth and so can hurt throughput.
6584 	 * So set it rather large, scaled by number of devices.
6585 	 */
6586 	conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
6587 	conf->shrinker.scan_objects = raid5_cache_scan;
6588 	conf->shrinker.count_objects = raid5_cache_count;
6589 	conf->shrinker.batch = 128;
6590 	conf->shrinker.flags = 0;
6591 	register_shrinker(&conf->shrinker);
6592 
6593 	sprintf(pers_name, "raid%d", mddev->new_level);
6594 	conf->thread = md_register_thread(raid5d, mddev, pers_name);
6595 	if (!conf->thread) {
6596 		printk(KERN_ERR
6597 		       "md/raid:%s: couldn't allocate thread.\n",
6598 		       mdname(mddev));
6599 		goto abort;
6600 	}
6601 
6602 	return conf;
6603 
6604  abort:
6605 	if (conf) {
6606 		free_conf(conf);
6607 		return ERR_PTR(-EIO);
6608 	} else
6609 		return ERR_PTR(-ENOMEM);
6610 }
6611 
6612 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
6613 {
6614 	switch (algo) {
6615 	case ALGORITHM_PARITY_0:
6616 		if (raid_disk < max_degraded)
6617 			return 1;
6618 		break;
6619 	case ALGORITHM_PARITY_N:
6620 		if (raid_disk >= raid_disks - max_degraded)
6621 			return 1;
6622 		break;
6623 	case ALGORITHM_PARITY_0_6:
6624 		if (raid_disk == 0 ||
6625 		    raid_disk == raid_disks - 1)
6626 			return 1;
6627 		break;
6628 	case ALGORITHM_LEFT_ASYMMETRIC_6:
6629 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
6630 	case ALGORITHM_LEFT_SYMMETRIC_6:
6631 	case ALGORITHM_RIGHT_SYMMETRIC_6:
6632 		if (raid_disk == raid_disks - 1)
6633 			return 1;
6634 	}
6635 	return 0;
6636 }
6637 
6638 static int run(struct mddev *mddev)
6639 {
6640 	struct r5conf *conf;
6641 	int working_disks = 0;
6642 	int dirty_parity_disks = 0;
6643 	struct md_rdev *rdev;
6644 	sector_t reshape_offset = 0;
6645 	int i;
6646 	long long min_offset_diff = 0;
6647 	int first = 1;
6648 
6649 	if (mddev->recovery_cp != MaxSector)
6650 		printk(KERN_NOTICE "md/raid:%s: not clean"
6651 		       " -- starting background reconstruction\n",
6652 		       mdname(mddev));
6653 
6654 	rdev_for_each(rdev, mddev) {
6655 		long long diff;
6656 		if (rdev->raid_disk < 0)
6657 			continue;
6658 		diff = (rdev->new_data_offset - rdev->data_offset);
6659 		if (first) {
6660 			min_offset_diff = diff;
6661 			first = 0;
6662 		} else if (mddev->reshape_backwards &&
6663 			 diff < min_offset_diff)
6664 			min_offset_diff = diff;
6665 		else if (!mddev->reshape_backwards &&
6666 			 diff > min_offset_diff)
6667 			min_offset_diff = diff;
6668 	}
6669 
6670 	if (mddev->reshape_position != MaxSector) {
6671 		/* Check that we can continue the reshape.
6672 		 * Difficulties arise if the stripe we would write to
6673 		 * next is at or after the stripe we would read from next.
6674 		 * For a reshape that changes the number of devices, this
6675 		 * is only possible for a very short time, and mdadm makes
6676 		 * sure that time appears to have past before assembling
6677 		 * the array.  So we fail if that time hasn't passed.
6678 		 * For a reshape that keeps the number of devices the same
6679 		 * mdadm must be monitoring the reshape can keeping the
6680 		 * critical areas read-only and backed up.  It will start
6681 		 * the array in read-only mode, so we check for that.
6682 		 */
6683 		sector_t here_new, here_old;
6684 		int old_disks;
6685 		int max_degraded = (mddev->level == 6 ? 2 : 1);
6686 
6687 		if (mddev->new_level != mddev->level) {
6688 			printk(KERN_ERR "md/raid:%s: unsupported reshape "
6689 			       "required - aborting.\n",
6690 			       mdname(mddev));
6691 			return -EINVAL;
6692 		}
6693 		old_disks = mddev->raid_disks - mddev->delta_disks;
6694 		/* reshape_position must be on a new-stripe boundary, and one
6695 		 * further up in new geometry must map after here in old
6696 		 * geometry.
6697 		 */
6698 		here_new = mddev->reshape_position;
6699 		if (sector_div(here_new, mddev->new_chunk_sectors *
6700 			       (mddev->raid_disks - max_degraded))) {
6701 			printk(KERN_ERR "md/raid:%s: reshape_position not "
6702 			       "on a stripe boundary\n", mdname(mddev));
6703 			return -EINVAL;
6704 		}
6705 		reshape_offset = here_new * mddev->new_chunk_sectors;
6706 		/* here_new is the stripe we will write to */
6707 		here_old = mddev->reshape_position;
6708 		sector_div(here_old, mddev->chunk_sectors *
6709 			   (old_disks-max_degraded));
6710 		/* here_old is the first stripe that we might need to read
6711 		 * from */
6712 		if (mddev->delta_disks == 0) {
6713 			if ((here_new * mddev->new_chunk_sectors !=
6714 			     here_old * mddev->chunk_sectors)) {
6715 				printk(KERN_ERR "md/raid:%s: reshape position is"
6716 				       " confused - aborting\n", mdname(mddev));
6717 				return -EINVAL;
6718 			}
6719 			/* We cannot be sure it is safe to start an in-place
6720 			 * reshape.  It is only safe if user-space is monitoring
6721 			 * and taking constant backups.
6722 			 * mdadm always starts a situation like this in
6723 			 * readonly mode so it can take control before
6724 			 * allowing any writes.  So just check for that.
6725 			 */
6726 			if (abs(min_offset_diff) >= mddev->chunk_sectors &&
6727 			    abs(min_offset_diff) >= mddev->new_chunk_sectors)
6728 				/* not really in-place - so OK */;
6729 			else if (mddev->ro == 0) {
6730 				printk(KERN_ERR "md/raid:%s: in-place reshape "
6731 				       "must be started in read-only mode "
6732 				       "- aborting\n",
6733 				       mdname(mddev));
6734 				return -EINVAL;
6735 			}
6736 		} else if (mddev->reshape_backwards
6737 		    ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=
6738 		       here_old * mddev->chunk_sectors)
6739 		    : (here_new * mddev->new_chunk_sectors >=
6740 		       here_old * mddev->chunk_sectors + (-min_offset_diff))) {
6741 			/* Reading from the same stripe as writing to - bad */
6742 			printk(KERN_ERR "md/raid:%s: reshape_position too early for "
6743 			       "auto-recovery - aborting.\n",
6744 			       mdname(mddev));
6745 			return -EINVAL;
6746 		}
6747 		printk(KERN_INFO "md/raid:%s: reshape will continue\n",
6748 		       mdname(mddev));
6749 		/* OK, we should be able to continue; */
6750 	} else {
6751 		BUG_ON(mddev->level != mddev->new_level);
6752 		BUG_ON(mddev->layout != mddev->new_layout);
6753 		BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
6754 		BUG_ON(mddev->delta_disks != 0);
6755 	}
6756 
6757 	if (mddev->private == NULL)
6758 		conf = setup_conf(mddev);
6759 	else
6760 		conf = mddev->private;
6761 
6762 	if (IS_ERR(conf))
6763 		return PTR_ERR(conf);
6764 
6765 	conf->min_offset_diff = min_offset_diff;
6766 	mddev->thread = conf->thread;
6767 	conf->thread = NULL;
6768 	mddev->private = conf;
6769 
6770 	for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
6771 	     i++) {
6772 		rdev = conf->disks[i].rdev;
6773 		if (!rdev && conf->disks[i].replacement) {
6774 			/* The replacement is all we have yet */
6775 			rdev = conf->disks[i].replacement;
6776 			conf->disks[i].replacement = NULL;
6777 			clear_bit(Replacement, &rdev->flags);
6778 			conf->disks[i].rdev = rdev;
6779 		}
6780 		if (!rdev)
6781 			continue;
6782 		if (conf->disks[i].replacement &&
6783 		    conf->reshape_progress != MaxSector) {
6784 			/* replacements and reshape simply do not mix. */
6785 			printk(KERN_ERR "md: cannot handle concurrent "
6786 			       "replacement and reshape.\n");
6787 			goto abort;
6788 		}
6789 		if (test_bit(In_sync, &rdev->flags)) {
6790 			working_disks++;
6791 			continue;
6792 		}
6793 		/* This disc is not fully in-sync.  However if it
6794 		 * just stored parity (beyond the recovery_offset),
6795 		 * when we don't need to be concerned about the
6796 		 * array being dirty.
6797 		 * When reshape goes 'backwards', we never have
6798 		 * partially completed devices, so we only need
6799 		 * to worry about reshape going forwards.
6800 		 */
6801 		/* Hack because v0.91 doesn't store recovery_offset properly. */
6802 		if (mddev->major_version == 0 &&
6803 		    mddev->minor_version > 90)
6804 			rdev->recovery_offset = reshape_offset;
6805 
6806 		if (rdev->recovery_offset < reshape_offset) {
6807 			/* We need to check old and new layout */
6808 			if (!only_parity(rdev->raid_disk,
6809 					 conf->algorithm,
6810 					 conf->raid_disks,
6811 					 conf->max_degraded))
6812 				continue;
6813 		}
6814 		if (!only_parity(rdev->raid_disk,
6815 				 conf->prev_algo,
6816 				 conf->previous_raid_disks,
6817 				 conf->max_degraded))
6818 			continue;
6819 		dirty_parity_disks++;
6820 	}
6821 
6822 	/*
6823 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
6824 	 */
6825 	mddev->degraded = calc_degraded(conf);
6826 
6827 	if (has_failed(conf)) {
6828 		printk(KERN_ERR "md/raid:%s: not enough operational devices"
6829 			" (%d/%d failed)\n",
6830 			mdname(mddev), mddev->degraded, conf->raid_disks);
6831 		goto abort;
6832 	}
6833 
6834 	/* device size must be a multiple of chunk size */
6835 	mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
6836 	mddev->resync_max_sectors = mddev->dev_sectors;
6837 
6838 	if (mddev->degraded > dirty_parity_disks &&
6839 	    mddev->recovery_cp != MaxSector) {
6840 		if (mddev->ok_start_degraded)
6841 			printk(KERN_WARNING
6842 			       "md/raid:%s: starting dirty degraded array"
6843 			       " - data corruption possible.\n",
6844 			       mdname(mddev));
6845 		else {
6846 			printk(KERN_ERR
6847 			       "md/raid:%s: cannot start dirty degraded array.\n",
6848 			       mdname(mddev));
6849 			goto abort;
6850 		}
6851 	}
6852 
6853 	if (mddev->degraded == 0)
6854 		printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
6855 		       " devices, algorithm %d\n", mdname(mddev), conf->level,
6856 		       mddev->raid_disks-mddev->degraded, mddev->raid_disks,
6857 		       mddev->new_layout);
6858 	else
6859 		printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
6860 		       " out of %d devices, algorithm %d\n",
6861 		       mdname(mddev), conf->level,
6862 		       mddev->raid_disks - mddev->degraded,
6863 		       mddev->raid_disks, mddev->new_layout);
6864 
6865 	print_raid5_conf(conf);
6866 
6867 	if (conf->reshape_progress != MaxSector) {
6868 		conf->reshape_safe = conf->reshape_progress;
6869 		atomic_set(&conf->reshape_stripes, 0);
6870 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6871 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6872 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6873 		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6874 		mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6875 							"reshape");
6876 	}
6877 
6878 	/* Ok, everything is just fine now */
6879 	if (mddev->to_remove == &raid5_attrs_group)
6880 		mddev->to_remove = NULL;
6881 	else if (mddev->kobj.sd &&
6882 	    sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
6883 		printk(KERN_WARNING
6884 		       "raid5: failed to create sysfs attributes for %s\n",
6885 		       mdname(mddev));
6886 	md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6887 
6888 	if (mddev->queue) {
6889 		int chunk_size;
6890 		bool discard_supported = true;
6891 		/* read-ahead size must cover two whole stripes, which
6892 		 * is 2 * (datadisks) * chunksize where 'n' is the
6893 		 * number of raid devices
6894 		 */
6895 		int data_disks = conf->previous_raid_disks - conf->max_degraded;
6896 		int stripe = data_disks *
6897 			((mddev->chunk_sectors << 9) / PAGE_SIZE);
6898 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6899 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6900 
6901 		chunk_size = mddev->chunk_sectors << 9;
6902 		blk_queue_io_min(mddev->queue, chunk_size);
6903 		blk_queue_io_opt(mddev->queue, chunk_size *
6904 				 (conf->raid_disks - conf->max_degraded));
6905 		mddev->queue->limits.raid_partial_stripes_expensive = 1;
6906 		/*
6907 		 * We can only discard a whole stripe. It doesn't make sense to
6908 		 * discard data disk but write parity disk
6909 		 */
6910 		stripe = stripe * PAGE_SIZE;
6911 		/* Round up to power of 2, as discard handling
6912 		 * currently assumes that */
6913 		while ((stripe-1) & stripe)
6914 			stripe = (stripe | (stripe-1)) + 1;
6915 		mddev->queue->limits.discard_alignment = stripe;
6916 		mddev->queue->limits.discard_granularity = stripe;
6917 		/*
6918 		 * unaligned part of discard request will be ignored, so can't
6919 		 * guarantee discard_zeroes_data
6920 		 */
6921 		mddev->queue->limits.discard_zeroes_data = 0;
6922 
6923 		blk_queue_max_write_same_sectors(mddev->queue, 0);
6924 
6925 		rdev_for_each(rdev, mddev) {
6926 			disk_stack_limits(mddev->gendisk, rdev->bdev,
6927 					  rdev->data_offset << 9);
6928 			disk_stack_limits(mddev->gendisk, rdev->bdev,
6929 					  rdev->new_data_offset << 9);
6930 			/*
6931 			 * discard_zeroes_data is required, otherwise data
6932 			 * could be lost. Consider a scenario: discard a stripe
6933 			 * (the stripe could be inconsistent if
6934 			 * discard_zeroes_data is 0); write one disk of the
6935 			 * stripe (the stripe could be inconsistent again
6936 			 * depending on which disks are used to calculate
6937 			 * parity); the disk is broken; The stripe data of this
6938 			 * disk is lost.
6939 			 */
6940 			if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
6941 			    !bdev_get_queue(rdev->bdev)->
6942 						limits.discard_zeroes_data)
6943 				discard_supported = false;
6944 			/* Unfortunately, discard_zeroes_data is not currently
6945 			 * a guarantee - just a hint.  So we only allow DISCARD
6946 			 * if the sysadmin has confirmed that only safe devices
6947 			 * are in use by setting a module parameter.
6948 			 */
6949 			if (!devices_handle_discard_safely) {
6950 				if (discard_supported) {
6951 					pr_info("md/raid456: discard support disabled due to uncertainty.\n");
6952 					pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
6953 				}
6954 				discard_supported = false;
6955 			}
6956 		}
6957 
6958 		if (discard_supported &&
6959 		   mddev->queue->limits.max_discard_sectors >= stripe &&
6960 		   mddev->queue->limits.discard_granularity >= stripe)
6961 			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
6962 						mddev->queue);
6963 		else
6964 			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
6965 						mddev->queue);
6966 	}
6967 
6968 	return 0;
6969 abort:
6970 	md_unregister_thread(&mddev->thread);
6971 	print_raid5_conf(conf);
6972 	free_conf(conf);
6973 	mddev->private = NULL;
6974 	printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
6975 	return -EIO;
6976 }
6977 
6978 static void raid5_free(struct mddev *mddev, void *priv)
6979 {
6980 	struct r5conf *conf = priv;
6981 
6982 	free_conf(conf);
6983 	mddev->to_remove = &raid5_attrs_group;
6984 }
6985 
6986 static void status(struct seq_file *seq, struct mddev *mddev)
6987 {
6988 	struct r5conf *conf = mddev->private;
6989 	int i;
6990 
6991 	seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
6992 		mddev->chunk_sectors / 2, mddev->layout);
6993 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
6994 	for (i = 0; i < conf->raid_disks; i++)
6995 		seq_printf (seq, "%s",
6996 			       conf->disks[i].rdev &&
6997 			       test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
6998 	seq_printf (seq, "]");
6999 }
7000 
7001 static void print_raid5_conf (struct r5conf *conf)
7002 {
7003 	int i;
7004 	struct disk_info *tmp;
7005 
7006 	printk(KERN_DEBUG "RAID conf printout:\n");
7007 	if (!conf) {
7008 		printk("(conf==NULL)\n");
7009 		return;
7010 	}
7011 	printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
7012 	       conf->raid_disks,
7013 	       conf->raid_disks - conf->mddev->degraded);
7014 
7015 	for (i = 0; i < conf->raid_disks; i++) {
7016 		char b[BDEVNAME_SIZE];
7017 		tmp = conf->disks + i;
7018 		if (tmp->rdev)
7019 			printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
7020 			       i, !test_bit(Faulty, &tmp->rdev->flags),
7021 			       bdevname(tmp->rdev->bdev, b));
7022 	}
7023 }
7024 
7025 static int raid5_spare_active(struct mddev *mddev)
7026 {
7027 	int i;
7028 	struct r5conf *conf = mddev->private;
7029 	struct disk_info *tmp;
7030 	int count = 0;
7031 	unsigned long flags;
7032 
7033 	for (i = 0; i < conf->raid_disks; i++) {
7034 		tmp = conf->disks + i;
7035 		if (tmp->replacement
7036 		    && tmp->replacement->recovery_offset == MaxSector
7037 		    && !test_bit(Faulty, &tmp->replacement->flags)
7038 		    && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7039 			/* Replacement has just become active. */
7040 			if (!tmp->rdev
7041 			    || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7042 				count++;
7043 			if (tmp->rdev) {
7044 				/* Replaced device not technically faulty,
7045 				 * but we need to be sure it gets removed
7046 				 * and never re-added.
7047 				 */
7048 				set_bit(Faulty, &tmp->rdev->flags);
7049 				sysfs_notify_dirent_safe(
7050 					tmp->rdev->sysfs_state);
7051 			}
7052 			sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7053 		} else if (tmp->rdev
7054 		    && tmp->rdev->recovery_offset == MaxSector
7055 		    && !test_bit(Faulty, &tmp->rdev->flags)
7056 		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7057 			count++;
7058 			sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7059 		}
7060 	}
7061 	spin_lock_irqsave(&conf->device_lock, flags);
7062 	mddev->degraded = calc_degraded(conf);
7063 	spin_unlock_irqrestore(&conf->device_lock, flags);
7064 	print_raid5_conf(conf);
7065 	return count;
7066 }
7067 
7068 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7069 {
7070 	struct r5conf *conf = mddev->private;
7071 	int err = 0;
7072 	int number = rdev->raid_disk;
7073 	struct md_rdev **rdevp;
7074 	struct disk_info *p = conf->disks + number;
7075 
7076 	print_raid5_conf(conf);
7077 	if (rdev == p->rdev)
7078 		rdevp = &p->rdev;
7079 	else if (rdev == p->replacement)
7080 		rdevp = &p->replacement;
7081 	else
7082 		return 0;
7083 
7084 	if (number >= conf->raid_disks &&
7085 	    conf->reshape_progress == MaxSector)
7086 		clear_bit(In_sync, &rdev->flags);
7087 
7088 	if (test_bit(In_sync, &rdev->flags) ||
7089 	    atomic_read(&rdev->nr_pending)) {
7090 		err = -EBUSY;
7091 		goto abort;
7092 	}
7093 	/* Only remove non-faulty devices if recovery
7094 	 * isn't possible.
7095 	 */
7096 	if (!test_bit(Faulty, &rdev->flags) &&
7097 	    mddev->recovery_disabled != conf->recovery_disabled &&
7098 	    !has_failed(conf) &&
7099 	    (!p->replacement || p->replacement == rdev) &&
7100 	    number < conf->raid_disks) {
7101 		err = -EBUSY;
7102 		goto abort;
7103 	}
7104 	*rdevp = NULL;
7105 	synchronize_rcu();
7106 	if (atomic_read(&rdev->nr_pending)) {
7107 		/* lost the race, try later */
7108 		err = -EBUSY;
7109 		*rdevp = rdev;
7110 	} else if (p->replacement) {
7111 		/* We must have just cleared 'rdev' */
7112 		p->rdev = p->replacement;
7113 		clear_bit(Replacement, &p->replacement->flags);
7114 		smp_mb(); /* Make sure other CPUs may see both as identical
7115 			   * but will never see neither - if they are careful
7116 			   */
7117 		p->replacement = NULL;
7118 		clear_bit(WantReplacement, &rdev->flags);
7119 	} else
7120 		/* We might have just removed the Replacement as faulty-
7121 		 * clear the bit just in case
7122 		 */
7123 		clear_bit(WantReplacement, &rdev->flags);
7124 abort:
7125 
7126 	print_raid5_conf(conf);
7127 	return err;
7128 }
7129 
7130 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7131 {
7132 	struct r5conf *conf = mddev->private;
7133 	int err = -EEXIST;
7134 	int disk;
7135 	struct disk_info *p;
7136 	int first = 0;
7137 	int last = conf->raid_disks - 1;
7138 
7139 	if (mddev->recovery_disabled == conf->recovery_disabled)
7140 		return -EBUSY;
7141 
7142 	if (rdev->saved_raid_disk < 0 && has_failed(conf))
7143 		/* no point adding a device */
7144 		return -EINVAL;
7145 
7146 	if (rdev->raid_disk >= 0)
7147 		first = last = rdev->raid_disk;
7148 
7149 	/*
7150 	 * find the disk ... but prefer rdev->saved_raid_disk
7151 	 * if possible.
7152 	 */
7153 	if (rdev->saved_raid_disk >= 0 &&
7154 	    rdev->saved_raid_disk >= first &&
7155 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
7156 		first = rdev->saved_raid_disk;
7157 
7158 	for (disk = first; disk <= last; disk++) {
7159 		p = conf->disks + disk;
7160 		if (p->rdev == NULL) {
7161 			clear_bit(In_sync, &rdev->flags);
7162 			rdev->raid_disk = disk;
7163 			err = 0;
7164 			if (rdev->saved_raid_disk != disk)
7165 				conf->fullsync = 1;
7166 			rcu_assign_pointer(p->rdev, rdev);
7167 			goto out;
7168 		}
7169 	}
7170 	for (disk = first; disk <= last; disk++) {
7171 		p = conf->disks + disk;
7172 		if (test_bit(WantReplacement, &p->rdev->flags) &&
7173 		    p->replacement == NULL) {
7174 			clear_bit(In_sync, &rdev->flags);
7175 			set_bit(Replacement, &rdev->flags);
7176 			rdev->raid_disk = disk;
7177 			err = 0;
7178 			conf->fullsync = 1;
7179 			rcu_assign_pointer(p->replacement, rdev);
7180 			break;
7181 		}
7182 	}
7183 out:
7184 	print_raid5_conf(conf);
7185 	return err;
7186 }
7187 
7188 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7189 {
7190 	/* no resync is happening, and there is enough space
7191 	 * on all devices, so we can resize.
7192 	 * We need to make sure resync covers any new space.
7193 	 * If the array is shrinking we should possibly wait until
7194 	 * any io in the removed space completes, but it hardly seems
7195 	 * worth it.
7196 	 */
7197 	sector_t newsize;
7198 	sectors &= ~((sector_t)mddev->chunk_sectors - 1);
7199 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7200 	if (mddev->external_size &&
7201 	    mddev->array_sectors > newsize)
7202 		return -EINVAL;
7203 	if (mddev->bitmap) {
7204 		int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7205 		if (ret)
7206 			return ret;
7207 	}
7208 	md_set_array_sectors(mddev, newsize);
7209 	set_capacity(mddev->gendisk, mddev->array_sectors);
7210 	revalidate_disk(mddev->gendisk);
7211 	if (sectors > mddev->dev_sectors &&
7212 	    mddev->recovery_cp > mddev->dev_sectors) {
7213 		mddev->recovery_cp = mddev->dev_sectors;
7214 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7215 	}
7216 	mddev->dev_sectors = sectors;
7217 	mddev->resync_max_sectors = sectors;
7218 	return 0;
7219 }
7220 
7221 static int check_stripe_cache(struct mddev *mddev)
7222 {
7223 	/* Can only proceed if there are plenty of stripe_heads.
7224 	 * We need a minimum of one full stripe,, and for sensible progress
7225 	 * it is best to have about 4 times that.
7226 	 * If we require 4 times, then the default 256 4K stripe_heads will
7227 	 * allow for chunk sizes up to 256K, which is probably OK.
7228 	 * If the chunk size is greater, user-space should request more
7229 	 * stripe_heads first.
7230 	 */
7231 	struct r5conf *conf = mddev->private;
7232 	if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7233 	    > conf->min_nr_stripes ||
7234 	    ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7235 	    > conf->min_nr_stripes) {
7236 		printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7237 		       mdname(mddev),
7238 		       ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7239 			/ STRIPE_SIZE)*4);
7240 		return 0;
7241 	}
7242 	return 1;
7243 }
7244 
7245 static int check_reshape(struct mddev *mddev)
7246 {
7247 	struct r5conf *conf = mddev->private;
7248 
7249 	if (mddev->delta_disks == 0 &&
7250 	    mddev->new_layout == mddev->layout &&
7251 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
7252 		return 0; /* nothing to do */
7253 	if (has_failed(conf))
7254 		return -EINVAL;
7255 	if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7256 		/* We might be able to shrink, but the devices must
7257 		 * be made bigger first.
7258 		 * For raid6, 4 is the minimum size.
7259 		 * Otherwise 2 is the minimum
7260 		 */
7261 		int min = 2;
7262 		if (mddev->level == 6)
7263 			min = 4;
7264 		if (mddev->raid_disks + mddev->delta_disks < min)
7265 			return -EINVAL;
7266 	}
7267 
7268 	if (!check_stripe_cache(mddev))
7269 		return -ENOSPC;
7270 
7271 	if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7272 	    mddev->delta_disks > 0)
7273 		if (resize_chunks(conf,
7274 				  conf->previous_raid_disks
7275 				  + max(0, mddev->delta_disks),
7276 				  max(mddev->new_chunk_sectors,
7277 				      mddev->chunk_sectors)
7278 			    ) < 0)
7279 			return -ENOMEM;
7280 	return resize_stripes(conf, (conf->previous_raid_disks
7281 				     + mddev->delta_disks));
7282 }
7283 
7284 static int raid5_start_reshape(struct mddev *mddev)
7285 {
7286 	struct r5conf *conf = mddev->private;
7287 	struct md_rdev *rdev;
7288 	int spares = 0;
7289 	unsigned long flags;
7290 
7291 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7292 		return -EBUSY;
7293 
7294 	if (!check_stripe_cache(mddev))
7295 		return -ENOSPC;
7296 
7297 	if (has_failed(conf))
7298 		return -EINVAL;
7299 
7300 	rdev_for_each(rdev, mddev) {
7301 		if (!test_bit(In_sync, &rdev->flags)
7302 		    && !test_bit(Faulty, &rdev->flags))
7303 			spares++;
7304 	}
7305 
7306 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7307 		/* Not enough devices even to make a degraded array
7308 		 * of that size
7309 		 */
7310 		return -EINVAL;
7311 
7312 	/* Refuse to reduce size of the array.  Any reductions in
7313 	 * array size must be through explicit setting of array_size
7314 	 * attribute.
7315 	 */
7316 	if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7317 	    < mddev->array_sectors) {
7318 		printk(KERN_ERR "md/raid:%s: array size must be reduced "
7319 		       "before number of disks\n", mdname(mddev));
7320 		return -EINVAL;
7321 	}
7322 
7323 	atomic_set(&conf->reshape_stripes, 0);
7324 	spin_lock_irq(&conf->device_lock);
7325 	write_seqcount_begin(&conf->gen_lock);
7326 	conf->previous_raid_disks = conf->raid_disks;
7327 	conf->raid_disks += mddev->delta_disks;
7328 	conf->prev_chunk_sectors = conf->chunk_sectors;
7329 	conf->chunk_sectors = mddev->new_chunk_sectors;
7330 	conf->prev_algo = conf->algorithm;
7331 	conf->algorithm = mddev->new_layout;
7332 	conf->generation++;
7333 	/* Code that selects data_offset needs to see the generation update
7334 	 * if reshape_progress has been set - so a memory barrier needed.
7335 	 */
7336 	smp_mb();
7337 	if (mddev->reshape_backwards)
7338 		conf->reshape_progress = raid5_size(mddev, 0, 0);
7339 	else
7340 		conf->reshape_progress = 0;
7341 	conf->reshape_safe = conf->reshape_progress;
7342 	write_seqcount_end(&conf->gen_lock);
7343 	spin_unlock_irq(&conf->device_lock);
7344 
7345 	/* Now make sure any requests that proceeded on the assumption
7346 	 * the reshape wasn't running - like Discard or Read - have
7347 	 * completed.
7348 	 */
7349 	mddev_suspend(mddev);
7350 	mddev_resume(mddev);
7351 
7352 	/* Add some new drives, as many as will fit.
7353 	 * We know there are enough to make the newly sized array work.
7354 	 * Don't add devices if we are reducing the number of
7355 	 * devices in the array.  This is because it is not possible
7356 	 * to correctly record the "partially reconstructed" state of
7357 	 * such devices during the reshape and confusion could result.
7358 	 */
7359 	if (mddev->delta_disks >= 0) {
7360 		rdev_for_each(rdev, mddev)
7361 			if (rdev->raid_disk < 0 &&
7362 			    !test_bit(Faulty, &rdev->flags)) {
7363 				if (raid5_add_disk(mddev, rdev) == 0) {
7364 					if (rdev->raid_disk
7365 					    >= conf->previous_raid_disks)
7366 						set_bit(In_sync, &rdev->flags);
7367 					else
7368 						rdev->recovery_offset = 0;
7369 
7370 					if (sysfs_link_rdev(mddev, rdev))
7371 						/* Failure here is OK */;
7372 				}
7373 			} else if (rdev->raid_disk >= conf->previous_raid_disks
7374 				   && !test_bit(Faulty, &rdev->flags)) {
7375 				/* This is a spare that was manually added */
7376 				set_bit(In_sync, &rdev->flags);
7377 			}
7378 
7379 		/* When a reshape changes the number of devices,
7380 		 * ->degraded is measured against the larger of the
7381 		 * pre and post number of devices.
7382 		 */
7383 		spin_lock_irqsave(&conf->device_lock, flags);
7384 		mddev->degraded = calc_degraded(conf);
7385 		spin_unlock_irqrestore(&conf->device_lock, flags);
7386 	}
7387 	mddev->raid_disks = conf->raid_disks;
7388 	mddev->reshape_position = conf->reshape_progress;
7389 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
7390 
7391 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7392 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7393 	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7394 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7395 	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7396 	mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7397 						"reshape");
7398 	if (!mddev->sync_thread) {
7399 		mddev->recovery = 0;
7400 		spin_lock_irq(&conf->device_lock);
7401 		write_seqcount_begin(&conf->gen_lock);
7402 		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7403 		mddev->new_chunk_sectors =
7404 			conf->chunk_sectors = conf->prev_chunk_sectors;
7405 		mddev->new_layout = conf->algorithm = conf->prev_algo;
7406 		rdev_for_each(rdev, mddev)
7407 			rdev->new_data_offset = rdev->data_offset;
7408 		smp_wmb();
7409 		conf->generation --;
7410 		conf->reshape_progress = MaxSector;
7411 		mddev->reshape_position = MaxSector;
7412 		write_seqcount_end(&conf->gen_lock);
7413 		spin_unlock_irq(&conf->device_lock);
7414 		return -EAGAIN;
7415 	}
7416 	conf->reshape_checkpoint = jiffies;
7417 	md_wakeup_thread(mddev->sync_thread);
7418 	md_new_event(mddev);
7419 	return 0;
7420 }
7421 
7422 /* This is called from the reshape thread and should make any
7423  * changes needed in 'conf'
7424  */
7425 static void end_reshape(struct r5conf *conf)
7426 {
7427 
7428 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7429 		struct md_rdev *rdev;
7430 
7431 		spin_lock_irq(&conf->device_lock);
7432 		conf->previous_raid_disks = conf->raid_disks;
7433 		rdev_for_each(rdev, conf->mddev)
7434 			rdev->data_offset = rdev->new_data_offset;
7435 		smp_wmb();
7436 		conf->reshape_progress = MaxSector;
7437 		spin_unlock_irq(&conf->device_lock);
7438 		wake_up(&conf->wait_for_overlap);
7439 
7440 		/* read-ahead size must cover two whole stripes, which is
7441 		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7442 		 */
7443 		if (conf->mddev->queue) {
7444 			int data_disks = conf->raid_disks - conf->max_degraded;
7445 			int stripe = data_disks * ((conf->chunk_sectors << 9)
7446 						   / PAGE_SIZE);
7447 			if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
7448 				conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
7449 		}
7450 	}
7451 }
7452 
7453 /* This is called from the raid5d thread with mddev_lock held.
7454  * It makes config changes to the device.
7455  */
7456 static void raid5_finish_reshape(struct mddev *mddev)
7457 {
7458 	struct r5conf *conf = mddev->private;
7459 
7460 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7461 
7462 		if (mddev->delta_disks > 0) {
7463 			md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7464 			set_capacity(mddev->gendisk, mddev->array_sectors);
7465 			revalidate_disk(mddev->gendisk);
7466 		} else {
7467 			int d;
7468 			spin_lock_irq(&conf->device_lock);
7469 			mddev->degraded = calc_degraded(conf);
7470 			spin_unlock_irq(&conf->device_lock);
7471 			for (d = conf->raid_disks ;
7472 			     d < conf->raid_disks - mddev->delta_disks;
7473 			     d++) {
7474 				struct md_rdev *rdev = conf->disks[d].rdev;
7475 				if (rdev)
7476 					clear_bit(In_sync, &rdev->flags);
7477 				rdev = conf->disks[d].replacement;
7478 				if (rdev)
7479 					clear_bit(In_sync, &rdev->flags);
7480 			}
7481 		}
7482 		mddev->layout = conf->algorithm;
7483 		mddev->chunk_sectors = conf->chunk_sectors;
7484 		mddev->reshape_position = MaxSector;
7485 		mddev->delta_disks = 0;
7486 		mddev->reshape_backwards = 0;
7487 	}
7488 }
7489 
7490 static void raid5_quiesce(struct mddev *mddev, int state)
7491 {
7492 	struct r5conf *conf = mddev->private;
7493 
7494 	switch(state) {
7495 	case 2: /* resume for a suspend */
7496 		wake_up(&conf->wait_for_overlap);
7497 		break;
7498 
7499 	case 1: /* stop all writes */
7500 		lock_all_device_hash_locks_irq(conf);
7501 		/* '2' tells resync/reshape to pause so that all
7502 		 * active stripes can drain
7503 		 */
7504 		conf->quiesce = 2;
7505 		wait_event_cmd(conf->wait_for_quiescent,
7506 				    atomic_read(&conf->active_stripes) == 0 &&
7507 				    atomic_read(&conf->active_aligned_reads) == 0,
7508 				    unlock_all_device_hash_locks_irq(conf),
7509 				    lock_all_device_hash_locks_irq(conf));
7510 		conf->quiesce = 1;
7511 		unlock_all_device_hash_locks_irq(conf);
7512 		/* allow reshape to continue */
7513 		wake_up(&conf->wait_for_overlap);
7514 		break;
7515 
7516 	case 0: /* re-enable writes */
7517 		lock_all_device_hash_locks_irq(conf);
7518 		conf->quiesce = 0;
7519 		wake_up(&conf->wait_for_quiescent);
7520 		wake_up(&conf->wait_for_overlap);
7521 		unlock_all_device_hash_locks_irq(conf);
7522 		break;
7523 	}
7524 }
7525 
7526 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
7527 {
7528 	struct r0conf *raid0_conf = mddev->private;
7529 	sector_t sectors;
7530 
7531 	/* for raid0 takeover only one zone is supported */
7532 	if (raid0_conf->nr_strip_zones > 1) {
7533 		printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
7534 		       mdname(mddev));
7535 		return ERR_PTR(-EINVAL);
7536 	}
7537 
7538 	sectors = raid0_conf->strip_zone[0].zone_end;
7539 	sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
7540 	mddev->dev_sectors = sectors;
7541 	mddev->new_level = level;
7542 	mddev->new_layout = ALGORITHM_PARITY_N;
7543 	mddev->new_chunk_sectors = mddev->chunk_sectors;
7544 	mddev->raid_disks += 1;
7545 	mddev->delta_disks = 1;
7546 	/* make sure it will be not marked as dirty */
7547 	mddev->recovery_cp = MaxSector;
7548 
7549 	return setup_conf(mddev);
7550 }
7551 
7552 static void *raid5_takeover_raid1(struct mddev *mddev)
7553 {
7554 	int chunksect;
7555 
7556 	if (mddev->raid_disks != 2 ||
7557 	    mddev->degraded > 1)
7558 		return ERR_PTR(-EINVAL);
7559 
7560 	/* Should check if there are write-behind devices? */
7561 
7562 	chunksect = 64*2; /* 64K by default */
7563 
7564 	/* The array must be an exact multiple of chunksize */
7565 	while (chunksect && (mddev->array_sectors & (chunksect-1)))
7566 		chunksect >>= 1;
7567 
7568 	if ((chunksect<<9) < STRIPE_SIZE)
7569 		/* array size does not allow a suitable chunk size */
7570 		return ERR_PTR(-EINVAL);
7571 
7572 	mddev->new_level = 5;
7573 	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
7574 	mddev->new_chunk_sectors = chunksect;
7575 
7576 	return setup_conf(mddev);
7577 }
7578 
7579 static void *raid5_takeover_raid6(struct mddev *mddev)
7580 {
7581 	int new_layout;
7582 
7583 	switch (mddev->layout) {
7584 	case ALGORITHM_LEFT_ASYMMETRIC_6:
7585 		new_layout = ALGORITHM_LEFT_ASYMMETRIC;
7586 		break;
7587 	case ALGORITHM_RIGHT_ASYMMETRIC_6:
7588 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
7589 		break;
7590 	case ALGORITHM_LEFT_SYMMETRIC_6:
7591 		new_layout = ALGORITHM_LEFT_SYMMETRIC;
7592 		break;
7593 	case ALGORITHM_RIGHT_SYMMETRIC_6:
7594 		new_layout = ALGORITHM_RIGHT_SYMMETRIC;
7595 		break;
7596 	case ALGORITHM_PARITY_0_6:
7597 		new_layout = ALGORITHM_PARITY_0;
7598 		break;
7599 	case ALGORITHM_PARITY_N:
7600 		new_layout = ALGORITHM_PARITY_N;
7601 		break;
7602 	default:
7603 		return ERR_PTR(-EINVAL);
7604 	}
7605 	mddev->new_level = 5;
7606 	mddev->new_layout = new_layout;
7607 	mddev->delta_disks = -1;
7608 	mddev->raid_disks -= 1;
7609 	return setup_conf(mddev);
7610 }
7611 
7612 static int raid5_check_reshape(struct mddev *mddev)
7613 {
7614 	/* For a 2-drive array, the layout and chunk size can be changed
7615 	 * immediately as not restriping is needed.
7616 	 * For larger arrays we record the new value - after validation
7617 	 * to be used by a reshape pass.
7618 	 */
7619 	struct r5conf *conf = mddev->private;
7620 	int new_chunk = mddev->new_chunk_sectors;
7621 
7622 	if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
7623 		return -EINVAL;
7624 	if (new_chunk > 0) {
7625 		if (!is_power_of_2(new_chunk))
7626 			return -EINVAL;
7627 		if (new_chunk < (PAGE_SIZE>>9))
7628 			return -EINVAL;
7629 		if (mddev->array_sectors & (new_chunk-1))
7630 			/* not factor of array size */
7631 			return -EINVAL;
7632 	}
7633 
7634 	/* They look valid */
7635 
7636 	if (mddev->raid_disks == 2) {
7637 		/* can make the change immediately */
7638 		if (mddev->new_layout >= 0) {
7639 			conf->algorithm = mddev->new_layout;
7640 			mddev->layout = mddev->new_layout;
7641 		}
7642 		if (new_chunk > 0) {
7643 			conf->chunk_sectors = new_chunk ;
7644 			mddev->chunk_sectors = new_chunk;
7645 		}
7646 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
7647 		md_wakeup_thread(mddev->thread);
7648 	}
7649 	return check_reshape(mddev);
7650 }
7651 
7652 static int raid6_check_reshape(struct mddev *mddev)
7653 {
7654 	int new_chunk = mddev->new_chunk_sectors;
7655 
7656 	if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
7657 		return -EINVAL;
7658 	if (new_chunk > 0) {
7659 		if (!is_power_of_2(new_chunk))
7660 			return -EINVAL;
7661 		if (new_chunk < (PAGE_SIZE >> 9))
7662 			return -EINVAL;
7663 		if (mddev->array_sectors & (new_chunk-1))
7664 			/* not factor of array size */
7665 			return -EINVAL;
7666 	}
7667 
7668 	/* They look valid */
7669 	return check_reshape(mddev);
7670 }
7671 
7672 static void *raid5_takeover(struct mddev *mddev)
7673 {
7674 	/* raid5 can take over:
7675 	 *  raid0 - if there is only one strip zone - make it a raid4 layout
7676 	 *  raid1 - if there are two drives.  We need to know the chunk size
7677 	 *  raid4 - trivial - just use a raid4 layout.
7678 	 *  raid6 - Providing it is a *_6 layout
7679 	 */
7680 	if (mddev->level == 0)
7681 		return raid45_takeover_raid0(mddev, 5);
7682 	if (mddev->level == 1)
7683 		return raid5_takeover_raid1(mddev);
7684 	if (mddev->level == 4) {
7685 		mddev->new_layout = ALGORITHM_PARITY_N;
7686 		mddev->new_level = 5;
7687 		return setup_conf(mddev);
7688 	}
7689 	if (mddev->level == 6)
7690 		return raid5_takeover_raid6(mddev);
7691 
7692 	return ERR_PTR(-EINVAL);
7693 }
7694 
7695 static void *raid4_takeover(struct mddev *mddev)
7696 {
7697 	/* raid4 can take over:
7698 	 *  raid0 - if there is only one strip zone
7699 	 *  raid5 - if layout is right
7700 	 */
7701 	if (mddev->level == 0)
7702 		return raid45_takeover_raid0(mddev, 4);
7703 	if (mddev->level == 5 &&
7704 	    mddev->layout == ALGORITHM_PARITY_N) {
7705 		mddev->new_layout = 0;
7706 		mddev->new_level = 4;
7707 		return setup_conf(mddev);
7708 	}
7709 	return ERR_PTR(-EINVAL);
7710 }
7711 
7712 static struct md_personality raid5_personality;
7713 
7714 static void *raid6_takeover(struct mddev *mddev)
7715 {
7716 	/* Currently can only take over a raid5.  We map the
7717 	 * personality to an equivalent raid6 personality
7718 	 * with the Q block at the end.
7719 	 */
7720 	int new_layout;
7721 
7722 	if (mddev->pers != &raid5_personality)
7723 		return ERR_PTR(-EINVAL);
7724 	if (mddev->degraded > 1)
7725 		return ERR_PTR(-EINVAL);
7726 	if (mddev->raid_disks > 253)
7727 		return ERR_PTR(-EINVAL);
7728 	if (mddev->raid_disks < 3)
7729 		return ERR_PTR(-EINVAL);
7730 
7731 	switch (mddev->layout) {
7732 	case ALGORITHM_LEFT_ASYMMETRIC:
7733 		new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
7734 		break;
7735 	case ALGORITHM_RIGHT_ASYMMETRIC:
7736 		new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
7737 		break;
7738 	case ALGORITHM_LEFT_SYMMETRIC:
7739 		new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
7740 		break;
7741 	case ALGORITHM_RIGHT_SYMMETRIC:
7742 		new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
7743 		break;
7744 	case ALGORITHM_PARITY_0:
7745 		new_layout = ALGORITHM_PARITY_0_6;
7746 		break;
7747 	case ALGORITHM_PARITY_N:
7748 		new_layout = ALGORITHM_PARITY_N;
7749 		break;
7750 	default:
7751 		return ERR_PTR(-EINVAL);
7752 	}
7753 	mddev->new_level = 6;
7754 	mddev->new_layout = new_layout;
7755 	mddev->delta_disks = 1;
7756 	mddev->raid_disks += 1;
7757 	return setup_conf(mddev);
7758 }
7759 
7760 static struct md_personality raid6_personality =
7761 {
7762 	.name		= "raid6",
7763 	.level		= 6,
7764 	.owner		= THIS_MODULE,
7765 	.make_request	= make_request,
7766 	.run		= run,
7767 	.free		= raid5_free,
7768 	.status		= status,
7769 	.error_handler	= error,
7770 	.hot_add_disk	= raid5_add_disk,
7771 	.hot_remove_disk= raid5_remove_disk,
7772 	.spare_active	= raid5_spare_active,
7773 	.sync_request	= sync_request,
7774 	.resize		= raid5_resize,
7775 	.size		= raid5_size,
7776 	.check_reshape	= raid6_check_reshape,
7777 	.start_reshape  = raid5_start_reshape,
7778 	.finish_reshape = raid5_finish_reshape,
7779 	.quiesce	= raid5_quiesce,
7780 	.takeover	= raid6_takeover,
7781 	.congested	= raid5_congested,
7782 	.mergeable_bvec	= raid5_mergeable_bvec,
7783 };
7784 static struct md_personality raid5_personality =
7785 {
7786 	.name		= "raid5",
7787 	.level		= 5,
7788 	.owner		= THIS_MODULE,
7789 	.make_request	= make_request,
7790 	.run		= run,
7791 	.free		= raid5_free,
7792 	.status		= status,
7793 	.error_handler	= error,
7794 	.hot_add_disk	= raid5_add_disk,
7795 	.hot_remove_disk= raid5_remove_disk,
7796 	.spare_active	= raid5_spare_active,
7797 	.sync_request	= sync_request,
7798 	.resize		= raid5_resize,
7799 	.size		= raid5_size,
7800 	.check_reshape	= raid5_check_reshape,
7801 	.start_reshape  = raid5_start_reshape,
7802 	.finish_reshape = raid5_finish_reshape,
7803 	.quiesce	= raid5_quiesce,
7804 	.takeover	= raid5_takeover,
7805 	.congested	= raid5_congested,
7806 	.mergeable_bvec	= raid5_mergeable_bvec,
7807 };
7808 
7809 static struct md_personality raid4_personality =
7810 {
7811 	.name		= "raid4",
7812 	.level		= 4,
7813 	.owner		= THIS_MODULE,
7814 	.make_request	= make_request,
7815 	.run		= run,
7816 	.free		= raid5_free,
7817 	.status		= status,
7818 	.error_handler	= error,
7819 	.hot_add_disk	= raid5_add_disk,
7820 	.hot_remove_disk= raid5_remove_disk,
7821 	.spare_active	= raid5_spare_active,
7822 	.sync_request	= sync_request,
7823 	.resize		= raid5_resize,
7824 	.size		= raid5_size,
7825 	.check_reshape	= raid5_check_reshape,
7826 	.start_reshape  = raid5_start_reshape,
7827 	.finish_reshape = raid5_finish_reshape,
7828 	.quiesce	= raid5_quiesce,
7829 	.takeover	= raid4_takeover,
7830 	.congested	= raid5_congested,
7831 	.mergeable_bvec	= raid5_mergeable_bvec,
7832 };
7833 
7834 static int __init raid5_init(void)
7835 {
7836 	raid5_wq = alloc_workqueue("raid5wq",
7837 		WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
7838 	if (!raid5_wq)
7839 		return -ENOMEM;
7840 	register_md_personality(&raid6_personality);
7841 	register_md_personality(&raid5_personality);
7842 	register_md_personality(&raid4_personality);
7843 	return 0;
7844 }
7845 
7846 static void raid5_exit(void)
7847 {
7848 	unregister_md_personality(&raid6_personality);
7849 	unregister_md_personality(&raid5_personality);
7850 	unregister_md_personality(&raid4_personality);
7851 	destroy_workqueue(raid5_wq);
7852 }
7853 
7854 module_init(raid5_init);
7855 module_exit(raid5_exit);
7856 MODULE_LICENSE("GPL");
7857 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
7858 MODULE_ALIAS("md-personality-4"); /* RAID5 */
7859 MODULE_ALIAS("md-raid5");
7860 MODULE_ALIAS("md-raid4");
7861 MODULE_ALIAS("md-level-5");
7862 MODULE_ALIAS("md-level-4");
7863 MODULE_ALIAS("md-personality-8"); /* RAID6 */
7864 MODULE_ALIAS("md-raid6");
7865 MODULE_ALIAS("md-level-6");
7866 
7867 /* This used to be two separate modules, they were: */
7868 MODULE_ALIAS("raid5");
7869 MODULE_ALIAS("raid6");
7870