xref: /openbmc/linux/drivers/md/raid5.c (revision 545e4006)
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->bm_write is the number of the last batch successfully written.
31  * conf->bm_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 bm_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/module.h>
47 #include <linux/slab.h>
48 #include <linux/highmem.h>
49 #include <linux/bitops.h>
50 #include <linux/kthread.h>
51 #include <asm/atomic.h>
52 #include "raid6.h"
53 
54 #include <linux/raid/bitmap.h>
55 #include <linux/async_tx.h>
56 
57 /*
58  * Stripe cache
59  */
60 
61 #define NR_STRIPES		256
62 #define STRIPE_SIZE		PAGE_SIZE
63 #define STRIPE_SHIFT		(PAGE_SHIFT - 9)
64 #define STRIPE_SECTORS		(STRIPE_SIZE>>9)
65 #define	IO_THRESHOLD		1
66 #define BYPASS_THRESHOLD	1
67 #define NR_HASH			(PAGE_SIZE / sizeof(struct hlist_head))
68 #define HASH_MASK		(NR_HASH - 1)
69 
70 #define stripe_hash(conf, sect)	(&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
71 
72 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
73  * order without overlap.  There may be several bio's per stripe+device, and
74  * a bio could span several devices.
75  * When walking this list for a particular stripe+device, we must never proceed
76  * beyond a bio that extends past this device, as the next bio might no longer
77  * be valid.
78  * This macro is used to determine the 'next' bio in the list, given the sector
79  * of the current stripe+device
80  */
81 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
82 /*
83  * The following can be used to debug the driver
84  */
85 #define RAID5_PARANOIA	1
86 #if RAID5_PARANOIA && defined(CONFIG_SMP)
87 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
88 #else
89 # define CHECK_DEVLOCK()
90 #endif
91 
92 #ifdef DEBUG
93 #define inline
94 #define __inline__
95 #endif
96 
97 #define printk_rl(args...) ((void) (printk_ratelimit() && printk(args)))
98 
99 #if !RAID6_USE_EMPTY_ZERO_PAGE
100 /* In .bss so it's zeroed */
101 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
102 #endif
103 
104 static inline int raid6_next_disk(int disk, int raid_disks)
105 {
106 	disk++;
107 	return (disk < raid_disks) ? disk : 0;
108 }
109 
110 static void return_io(struct bio *return_bi)
111 {
112 	struct bio *bi = return_bi;
113 	while (bi) {
114 
115 		return_bi = bi->bi_next;
116 		bi->bi_next = NULL;
117 		bi->bi_size = 0;
118 		bio_endio(bi, 0);
119 		bi = return_bi;
120 	}
121 }
122 
123 static void print_raid5_conf (raid5_conf_t *conf);
124 
125 static int stripe_operations_active(struct stripe_head *sh)
126 {
127 	return sh->check_state || sh->reconstruct_state ||
128 	       test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
129 	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);
130 }
131 
132 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
133 {
134 	if (atomic_dec_and_test(&sh->count)) {
135 		BUG_ON(!list_empty(&sh->lru));
136 		BUG_ON(atomic_read(&conf->active_stripes)==0);
137 		if (test_bit(STRIPE_HANDLE, &sh->state)) {
138 			if (test_bit(STRIPE_DELAYED, &sh->state)) {
139 				list_add_tail(&sh->lru, &conf->delayed_list);
140 				blk_plug_device(conf->mddev->queue);
141 			} else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
142 				   sh->bm_seq - conf->seq_write > 0) {
143 				list_add_tail(&sh->lru, &conf->bitmap_list);
144 				blk_plug_device(conf->mddev->queue);
145 			} else {
146 				clear_bit(STRIPE_BIT_DELAY, &sh->state);
147 				list_add_tail(&sh->lru, &conf->handle_list);
148 			}
149 			md_wakeup_thread(conf->mddev->thread);
150 		} else {
151 			BUG_ON(stripe_operations_active(sh));
152 			if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
153 				atomic_dec(&conf->preread_active_stripes);
154 				if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
155 					md_wakeup_thread(conf->mddev->thread);
156 			}
157 			atomic_dec(&conf->active_stripes);
158 			if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
159 				list_add_tail(&sh->lru, &conf->inactive_list);
160 				wake_up(&conf->wait_for_stripe);
161 				if (conf->retry_read_aligned)
162 					md_wakeup_thread(conf->mddev->thread);
163 			}
164 		}
165 	}
166 }
167 static void release_stripe(struct stripe_head *sh)
168 {
169 	raid5_conf_t *conf = sh->raid_conf;
170 	unsigned long flags;
171 
172 	spin_lock_irqsave(&conf->device_lock, flags);
173 	__release_stripe(conf, sh);
174 	spin_unlock_irqrestore(&conf->device_lock, flags);
175 }
176 
177 static inline void remove_hash(struct stripe_head *sh)
178 {
179 	pr_debug("remove_hash(), stripe %llu\n",
180 		(unsigned long long)sh->sector);
181 
182 	hlist_del_init(&sh->hash);
183 }
184 
185 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
186 {
187 	struct hlist_head *hp = stripe_hash(conf, sh->sector);
188 
189 	pr_debug("insert_hash(), stripe %llu\n",
190 		(unsigned long long)sh->sector);
191 
192 	CHECK_DEVLOCK();
193 	hlist_add_head(&sh->hash, hp);
194 }
195 
196 
197 /* find an idle stripe, make sure it is unhashed, and return it. */
198 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
199 {
200 	struct stripe_head *sh = NULL;
201 	struct list_head *first;
202 
203 	CHECK_DEVLOCK();
204 	if (list_empty(&conf->inactive_list))
205 		goto out;
206 	first = conf->inactive_list.next;
207 	sh = list_entry(first, struct stripe_head, lru);
208 	list_del_init(first);
209 	remove_hash(sh);
210 	atomic_inc(&conf->active_stripes);
211 out:
212 	return sh;
213 }
214 
215 static void shrink_buffers(struct stripe_head *sh, int num)
216 {
217 	struct page *p;
218 	int i;
219 
220 	for (i=0; i<num ; i++) {
221 		p = sh->dev[i].page;
222 		if (!p)
223 			continue;
224 		sh->dev[i].page = NULL;
225 		put_page(p);
226 	}
227 }
228 
229 static int grow_buffers(struct stripe_head *sh, int num)
230 {
231 	int i;
232 
233 	for (i=0; i<num; i++) {
234 		struct page *page;
235 
236 		if (!(page = alloc_page(GFP_KERNEL))) {
237 			return 1;
238 		}
239 		sh->dev[i].page = page;
240 	}
241 	return 0;
242 }
243 
244 static void raid5_build_block (struct stripe_head *sh, int i);
245 
246 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
247 {
248 	raid5_conf_t *conf = sh->raid_conf;
249 	int i;
250 
251 	BUG_ON(atomic_read(&sh->count) != 0);
252 	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
253 	BUG_ON(stripe_operations_active(sh));
254 
255 	CHECK_DEVLOCK();
256 	pr_debug("init_stripe called, stripe %llu\n",
257 		(unsigned long long)sh->sector);
258 
259 	remove_hash(sh);
260 
261 	sh->sector = sector;
262 	sh->pd_idx = pd_idx;
263 	sh->state = 0;
264 
265 	sh->disks = disks;
266 
267 	for (i = sh->disks; i--; ) {
268 		struct r5dev *dev = &sh->dev[i];
269 
270 		if (dev->toread || dev->read || dev->towrite || dev->written ||
271 		    test_bit(R5_LOCKED, &dev->flags)) {
272 			printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
273 			       (unsigned long long)sh->sector, i, dev->toread,
274 			       dev->read, dev->towrite, dev->written,
275 			       test_bit(R5_LOCKED, &dev->flags));
276 			BUG();
277 		}
278 		dev->flags = 0;
279 		raid5_build_block(sh, i);
280 	}
281 	insert_hash(conf, sh);
282 }
283 
284 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
285 {
286 	struct stripe_head *sh;
287 	struct hlist_node *hn;
288 
289 	CHECK_DEVLOCK();
290 	pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
291 	hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
292 		if (sh->sector == sector && sh->disks == disks)
293 			return sh;
294 	pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
295 	return NULL;
296 }
297 
298 static void unplug_slaves(mddev_t *mddev);
299 static void raid5_unplug_device(struct request_queue *q);
300 
301 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
302 					     int pd_idx, int noblock)
303 {
304 	struct stripe_head *sh;
305 
306 	pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
307 
308 	spin_lock_irq(&conf->device_lock);
309 
310 	do {
311 		wait_event_lock_irq(conf->wait_for_stripe,
312 				    conf->quiesce == 0,
313 				    conf->device_lock, /* nothing */);
314 		sh = __find_stripe(conf, sector, disks);
315 		if (!sh) {
316 			if (!conf->inactive_blocked)
317 				sh = get_free_stripe(conf);
318 			if (noblock && sh == NULL)
319 				break;
320 			if (!sh) {
321 				conf->inactive_blocked = 1;
322 				wait_event_lock_irq(conf->wait_for_stripe,
323 						    !list_empty(&conf->inactive_list) &&
324 						    (atomic_read(&conf->active_stripes)
325 						     < (conf->max_nr_stripes *3/4)
326 						     || !conf->inactive_blocked),
327 						    conf->device_lock,
328 						    raid5_unplug_device(conf->mddev->queue)
329 					);
330 				conf->inactive_blocked = 0;
331 			} else
332 				init_stripe(sh, sector, pd_idx, disks);
333 		} else {
334 			if (atomic_read(&sh->count)) {
335 			  BUG_ON(!list_empty(&sh->lru));
336 			} else {
337 				if (!test_bit(STRIPE_HANDLE, &sh->state))
338 					atomic_inc(&conf->active_stripes);
339 				if (list_empty(&sh->lru) &&
340 				    !test_bit(STRIPE_EXPANDING, &sh->state))
341 					BUG();
342 				list_del_init(&sh->lru);
343 			}
344 		}
345 	} while (sh == NULL);
346 
347 	if (sh)
348 		atomic_inc(&sh->count);
349 
350 	spin_unlock_irq(&conf->device_lock);
351 	return sh;
352 }
353 
354 static void
355 raid5_end_read_request(struct bio *bi, int error);
356 static void
357 raid5_end_write_request(struct bio *bi, int error);
358 
359 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
360 {
361 	raid5_conf_t *conf = sh->raid_conf;
362 	int i, disks = sh->disks;
363 
364 	might_sleep();
365 
366 	for (i = disks; i--; ) {
367 		int rw;
368 		struct bio *bi;
369 		mdk_rdev_t *rdev;
370 		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
371 			rw = WRITE;
372 		else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
373 			rw = READ;
374 		else
375 			continue;
376 
377 		bi = &sh->dev[i].req;
378 
379 		bi->bi_rw = rw;
380 		if (rw == WRITE)
381 			bi->bi_end_io = raid5_end_write_request;
382 		else
383 			bi->bi_end_io = raid5_end_read_request;
384 
385 		rcu_read_lock();
386 		rdev = rcu_dereference(conf->disks[i].rdev);
387 		if (rdev && test_bit(Faulty, &rdev->flags))
388 			rdev = NULL;
389 		if (rdev)
390 			atomic_inc(&rdev->nr_pending);
391 		rcu_read_unlock();
392 
393 		if (rdev) {
394 			if (s->syncing || s->expanding || s->expanded)
395 				md_sync_acct(rdev->bdev, STRIPE_SECTORS);
396 
397 			set_bit(STRIPE_IO_STARTED, &sh->state);
398 
399 			bi->bi_bdev = rdev->bdev;
400 			pr_debug("%s: for %llu schedule op %ld on disc %d\n",
401 				__func__, (unsigned long long)sh->sector,
402 				bi->bi_rw, i);
403 			atomic_inc(&sh->count);
404 			bi->bi_sector = sh->sector + rdev->data_offset;
405 			bi->bi_flags = 1 << BIO_UPTODATE;
406 			bi->bi_vcnt = 1;
407 			bi->bi_max_vecs = 1;
408 			bi->bi_idx = 0;
409 			bi->bi_io_vec = &sh->dev[i].vec;
410 			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
411 			bi->bi_io_vec[0].bv_offset = 0;
412 			bi->bi_size = STRIPE_SIZE;
413 			bi->bi_next = NULL;
414 			if (rw == WRITE &&
415 			    test_bit(R5_ReWrite, &sh->dev[i].flags))
416 				atomic_add(STRIPE_SECTORS,
417 					&rdev->corrected_errors);
418 			generic_make_request(bi);
419 		} else {
420 			if (rw == WRITE)
421 				set_bit(STRIPE_DEGRADED, &sh->state);
422 			pr_debug("skip op %ld on disc %d for sector %llu\n",
423 				bi->bi_rw, i, (unsigned long long)sh->sector);
424 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
425 			set_bit(STRIPE_HANDLE, &sh->state);
426 		}
427 	}
428 }
429 
430 static struct dma_async_tx_descriptor *
431 async_copy_data(int frombio, struct bio *bio, struct page *page,
432 	sector_t sector, struct dma_async_tx_descriptor *tx)
433 {
434 	struct bio_vec *bvl;
435 	struct page *bio_page;
436 	int i;
437 	int page_offset;
438 
439 	if (bio->bi_sector >= sector)
440 		page_offset = (signed)(bio->bi_sector - sector) * 512;
441 	else
442 		page_offset = (signed)(sector - bio->bi_sector) * -512;
443 	bio_for_each_segment(bvl, bio, i) {
444 		int len = bio_iovec_idx(bio, i)->bv_len;
445 		int clen;
446 		int b_offset = 0;
447 
448 		if (page_offset < 0) {
449 			b_offset = -page_offset;
450 			page_offset += b_offset;
451 			len -= b_offset;
452 		}
453 
454 		if (len > 0 && page_offset + len > STRIPE_SIZE)
455 			clen = STRIPE_SIZE - page_offset;
456 		else
457 			clen = len;
458 
459 		if (clen > 0) {
460 			b_offset += bio_iovec_idx(bio, i)->bv_offset;
461 			bio_page = bio_iovec_idx(bio, i)->bv_page;
462 			if (frombio)
463 				tx = async_memcpy(page, bio_page, page_offset,
464 					b_offset, clen,
465 					ASYNC_TX_DEP_ACK,
466 					tx, NULL, NULL);
467 			else
468 				tx = async_memcpy(bio_page, page, b_offset,
469 					page_offset, clen,
470 					ASYNC_TX_DEP_ACK,
471 					tx, NULL, NULL);
472 		}
473 		if (clen < len) /* hit end of page */
474 			break;
475 		page_offset +=  len;
476 	}
477 
478 	return tx;
479 }
480 
481 static void ops_complete_biofill(void *stripe_head_ref)
482 {
483 	struct stripe_head *sh = stripe_head_ref;
484 	struct bio *return_bi = NULL;
485 	raid5_conf_t *conf = sh->raid_conf;
486 	int i;
487 
488 	pr_debug("%s: stripe %llu\n", __func__,
489 		(unsigned long long)sh->sector);
490 
491 	/* clear completed biofills */
492 	spin_lock_irq(&conf->device_lock);
493 	for (i = sh->disks; i--; ) {
494 		struct r5dev *dev = &sh->dev[i];
495 
496 		/* acknowledge completion of a biofill operation */
497 		/* and check if we need to reply to a read request,
498 		 * new R5_Wantfill requests are held off until
499 		 * !STRIPE_BIOFILL_RUN
500 		 */
501 		if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
502 			struct bio *rbi, *rbi2;
503 
504 			BUG_ON(!dev->read);
505 			rbi = dev->read;
506 			dev->read = NULL;
507 			while (rbi && rbi->bi_sector <
508 				dev->sector + STRIPE_SECTORS) {
509 				rbi2 = r5_next_bio(rbi, dev->sector);
510 				if (--rbi->bi_phys_segments == 0) {
511 					rbi->bi_next = return_bi;
512 					return_bi = rbi;
513 				}
514 				rbi = rbi2;
515 			}
516 		}
517 	}
518 	spin_unlock_irq(&conf->device_lock);
519 	clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
520 
521 	return_io(return_bi);
522 
523 	set_bit(STRIPE_HANDLE, &sh->state);
524 	release_stripe(sh);
525 }
526 
527 static void ops_run_biofill(struct stripe_head *sh)
528 {
529 	struct dma_async_tx_descriptor *tx = NULL;
530 	raid5_conf_t *conf = sh->raid_conf;
531 	int i;
532 
533 	pr_debug("%s: stripe %llu\n", __func__,
534 		(unsigned long long)sh->sector);
535 
536 	for (i = sh->disks; i--; ) {
537 		struct r5dev *dev = &sh->dev[i];
538 		if (test_bit(R5_Wantfill, &dev->flags)) {
539 			struct bio *rbi;
540 			spin_lock_irq(&conf->device_lock);
541 			dev->read = rbi = dev->toread;
542 			dev->toread = NULL;
543 			spin_unlock_irq(&conf->device_lock);
544 			while (rbi && rbi->bi_sector <
545 				dev->sector + STRIPE_SECTORS) {
546 				tx = async_copy_data(0, rbi, dev->page,
547 					dev->sector, tx);
548 				rbi = r5_next_bio(rbi, dev->sector);
549 			}
550 		}
551 	}
552 
553 	atomic_inc(&sh->count);
554 	async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
555 		ops_complete_biofill, sh);
556 }
557 
558 static void ops_complete_compute5(void *stripe_head_ref)
559 {
560 	struct stripe_head *sh = stripe_head_ref;
561 	int target = sh->ops.target;
562 	struct r5dev *tgt = &sh->dev[target];
563 
564 	pr_debug("%s: stripe %llu\n", __func__,
565 		(unsigned long long)sh->sector);
566 
567 	set_bit(R5_UPTODATE, &tgt->flags);
568 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
569 	clear_bit(R5_Wantcompute, &tgt->flags);
570 	clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
571 	if (sh->check_state == check_state_compute_run)
572 		sh->check_state = check_state_compute_result;
573 	set_bit(STRIPE_HANDLE, &sh->state);
574 	release_stripe(sh);
575 }
576 
577 static struct dma_async_tx_descriptor *ops_run_compute5(struct stripe_head *sh)
578 {
579 	/* kernel stack size limits the total number of disks */
580 	int disks = sh->disks;
581 	struct page *xor_srcs[disks];
582 	int target = sh->ops.target;
583 	struct r5dev *tgt = &sh->dev[target];
584 	struct page *xor_dest = tgt->page;
585 	int count = 0;
586 	struct dma_async_tx_descriptor *tx;
587 	int i;
588 
589 	pr_debug("%s: stripe %llu block: %d\n",
590 		__func__, (unsigned long long)sh->sector, target);
591 	BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
592 
593 	for (i = disks; i--; )
594 		if (i != target)
595 			xor_srcs[count++] = sh->dev[i].page;
596 
597 	atomic_inc(&sh->count);
598 
599 	if (unlikely(count == 1))
600 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
601 			0, NULL, ops_complete_compute5, sh);
602 	else
603 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
604 			ASYNC_TX_XOR_ZERO_DST, NULL,
605 			ops_complete_compute5, sh);
606 
607 	return tx;
608 }
609 
610 static void ops_complete_prexor(void *stripe_head_ref)
611 {
612 	struct stripe_head *sh = stripe_head_ref;
613 
614 	pr_debug("%s: stripe %llu\n", __func__,
615 		(unsigned long long)sh->sector);
616 }
617 
618 static struct dma_async_tx_descriptor *
619 ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
620 {
621 	/* kernel stack size limits the total number of disks */
622 	int disks = sh->disks;
623 	struct page *xor_srcs[disks];
624 	int count = 0, pd_idx = sh->pd_idx, i;
625 
626 	/* existing parity data subtracted */
627 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
628 
629 	pr_debug("%s: stripe %llu\n", __func__,
630 		(unsigned long long)sh->sector);
631 
632 	for (i = disks; i--; ) {
633 		struct r5dev *dev = &sh->dev[i];
634 		/* Only process blocks that are known to be uptodate */
635 		if (test_bit(R5_Wantdrain, &dev->flags))
636 			xor_srcs[count++] = dev->page;
637 	}
638 
639 	tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
640 		ASYNC_TX_DEP_ACK | ASYNC_TX_XOR_DROP_DST, tx,
641 		ops_complete_prexor, sh);
642 
643 	return tx;
644 }
645 
646 static struct dma_async_tx_descriptor *
647 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
648 {
649 	int disks = sh->disks;
650 	int i;
651 
652 	pr_debug("%s: stripe %llu\n", __func__,
653 		(unsigned long long)sh->sector);
654 
655 	for (i = disks; i--; ) {
656 		struct r5dev *dev = &sh->dev[i];
657 		struct bio *chosen;
658 
659 		if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
660 			struct bio *wbi;
661 
662 			spin_lock(&sh->lock);
663 			chosen = dev->towrite;
664 			dev->towrite = NULL;
665 			BUG_ON(dev->written);
666 			wbi = dev->written = chosen;
667 			spin_unlock(&sh->lock);
668 
669 			while (wbi && wbi->bi_sector <
670 				dev->sector + STRIPE_SECTORS) {
671 				tx = async_copy_data(1, wbi, dev->page,
672 					dev->sector, tx);
673 				wbi = r5_next_bio(wbi, dev->sector);
674 			}
675 		}
676 	}
677 
678 	return tx;
679 }
680 
681 static void ops_complete_postxor(void *stripe_head_ref)
682 {
683 	struct stripe_head *sh = stripe_head_ref;
684 	int disks = sh->disks, i, pd_idx = sh->pd_idx;
685 
686 	pr_debug("%s: stripe %llu\n", __func__,
687 		(unsigned long long)sh->sector);
688 
689 	for (i = disks; i--; ) {
690 		struct r5dev *dev = &sh->dev[i];
691 		if (dev->written || i == pd_idx)
692 			set_bit(R5_UPTODATE, &dev->flags);
693 	}
694 
695 	if (sh->reconstruct_state == reconstruct_state_drain_run)
696 		sh->reconstruct_state = reconstruct_state_drain_result;
697 	else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
698 		sh->reconstruct_state = reconstruct_state_prexor_drain_result;
699 	else {
700 		BUG_ON(sh->reconstruct_state != reconstruct_state_run);
701 		sh->reconstruct_state = reconstruct_state_result;
702 	}
703 
704 	set_bit(STRIPE_HANDLE, &sh->state);
705 	release_stripe(sh);
706 }
707 
708 static void
709 ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
710 {
711 	/* kernel stack size limits the total number of disks */
712 	int disks = sh->disks;
713 	struct page *xor_srcs[disks];
714 
715 	int count = 0, pd_idx = sh->pd_idx, i;
716 	struct page *xor_dest;
717 	int prexor = 0;
718 	unsigned long flags;
719 
720 	pr_debug("%s: stripe %llu\n", __func__,
721 		(unsigned long long)sh->sector);
722 
723 	/* check if prexor is active which means only process blocks
724 	 * that are part of a read-modify-write (written)
725 	 */
726 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
727 		prexor = 1;
728 		xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
729 		for (i = disks; i--; ) {
730 			struct r5dev *dev = &sh->dev[i];
731 			if (dev->written)
732 				xor_srcs[count++] = dev->page;
733 		}
734 	} else {
735 		xor_dest = sh->dev[pd_idx].page;
736 		for (i = disks; i--; ) {
737 			struct r5dev *dev = &sh->dev[i];
738 			if (i != pd_idx)
739 				xor_srcs[count++] = dev->page;
740 		}
741 	}
742 
743 	/* 1/ if we prexor'd then the dest is reused as a source
744 	 * 2/ if we did not prexor then we are redoing the parity
745 	 * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
746 	 * for the synchronous xor case
747 	 */
748 	flags = ASYNC_TX_DEP_ACK | ASYNC_TX_ACK |
749 		(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
750 
751 	atomic_inc(&sh->count);
752 
753 	if (unlikely(count == 1)) {
754 		flags &= ~(ASYNC_TX_XOR_DROP_DST | ASYNC_TX_XOR_ZERO_DST);
755 		tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
756 			flags, tx, ops_complete_postxor, sh);
757 	} else
758 		tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
759 			flags, tx, ops_complete_postxor, sh);
760 }
761 
762 static void ops_complete_check(void *stripe_head_ref)
763 {
764 	struct stripe_head *sh = stripe_head_ref;
765 
766 	pr_debug("%s: stripe %llu\n", __func__,
767 		(unsigned long long)sh->sector);
768 
769 	sh->check_state = check_state_check_result;
770 	set_bit(STRIPE_HANDLE, &sh->state);
771 	release_stripe(sh);
772 }
773 
774 static void ops_run_check(struct stripe_head *sh)
775 {
776 	/* kernel stack size limits the total number of disks */
777 	int disks = sh->disks;
778 	struct page *xor_srcs[disks];
779 	struct dma_async_tx_descriptor *tx;
780 
781 	int count = 0, pd_idx = sh->pd_idx, i;
782 	struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
783 
784 	pr_debug("%s: stripe %llu\n", __func__,
785 		(unsigned long long)sh->sector);
786 
787 	for (i = disks; i--; ) {
788 		struct r5dev *dev = &sh->dev[i];
789 		if (i != pd_idx)
790 			xor_srcs[count++] = dev->page;
791 	}
792 
793 	tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
794 		&sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
795 
796 	atomic_inc(&sh->count);
797 	tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
798 		ops_complete_check, sh);
799 }
800 
801 static void raid5_run_ops(struct stripe_head *sh, unsigned long ops_request)
802 {
803 	int overlap_clear = 0, i, disks = sh->disks;
804 	struct dma_async_tx_descriptor *tx = NULL;
805 
806 	if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
807 		ops_run_biofill(sh);
808 		overlap_clear++;
809 	}
810 
811 	if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
812 		tx = ops_run_compute5(sh);
813 		/* terminate the chain if postxor is not set to be run */
814 		if (tx && !test_bit(STRIPE_OP_POSTXOR, &ops_request))
815 			async_tx_ack(tx);
816 	}
817 
818 	if (test_bit(STRIPE_OP_PREXOR, &ops_request))
819 		tx = ops_run_prexor(sh, tx);
820 
821 	if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
822 		tx = ops_run_biodrain(sh, tx);
823 		overlap_clear++;
824 	}
825 
826 	if (test_bit(STRIPE_OP_POSTXOR, &ops_request))
827 		ops_run_postxor(sh, tx);
828 
829 	if (test_bit(STRIPE_OP_CHECK, &ops_request))
830 		ops_run_check(sh);
831 
832 	if (overlap_clear)
833 		for (i = disks; i--; ) {
834 			struct r5dev *dev = &sh->dev[i];
835 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
836 				wake_up(&sh->raid_conf->wait_for_overlap);
837 		}
838 }
839 
840 static int grow_one_stripe(raid5_conf_t *conf)
841 {
842 	struct stripe_head *sh;
843 	sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
844 	if (!sh)
845 		return 0;
846 	memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
847 	sh->raid_conf = conf;
848 	spin_lock_init(&sh->lock);
849 
850 	if (grow_buffers(sh, conf->raid_disks)) {
851 		shrink_buffers(sh, conf->raid_disks);
852 		kmem_cache_free(conf->slab_cache, sh);
853 		return 0;
854 	}
855 	sh->disks = conf->raid_disks;
856 	/* we just created an active stripe so... */
857 	atomic_set(&sh->count, 1);
858 	atomic_inc(&conf->active_stripes);
859 	INIT_LIST_HEAD(&sh->lru);
860 	release_stripe(sh);
861 	return 1;
862 }
863 
864 static int grow_stripes(raid5_conf_t *conf, int num)
865 {
866 	struct kmem_cache *sc;
867 	int devs = conf->raid_disks;
868 
869 	sprintf(conf->cache_name[0], "raid5-%s", mdname(conf->mddev));
870 	sprintf(conf->cache_name[1], "raid5-%s-alt", mdname(conf->mddev));
871 	conf->active_name = 0;
872 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
873 			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
874 			       0, 0, NULL);
875 	if (!sc)
876 		return 1;
877 	conf->slab_cache = sc;
878 	conf->pool_size = devs;
879 	while (num--)
880 		if (!grow_one_stripe(conf))
881 			return 1;
882 	return 0;
883 }
884 
885 #ifdef CONFIG_MD_RAID5_RESHAPE
886 static int resize_stripes(raid5_conf_t *conf, int newsize)
887 {
888 	/* Make all the stripes able to hold 'newsize' devices.
889 	 * New slots in each stripe get 'page' set to a new page.
890 	 *
891 	 * This happens in stages:
892 	 * 1/ create a new kmem_cache and allocate the required number of
893 	 *    stripe_heads.
894 	 * 2/ gather all the old stripe_heads and tranfer the pages across
895 	 *    to the new stripe_heads.  This will have the side effect of
896 	 *    freezing the array as once all stripe_heads have been collected,
897 	 *    no IO will be possible.  Old stripe heads are freed once their
898 	 *    pages have been transferred over, and the old kmem_cache is
899 	 *    freed when all stripes are done.
900 	 * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
901 	 *    we simple return a failre status - no need to clean anything up.
902 	 * 4/ allocate new pages for the new slots in the new stripe_heads.
903 	 *    If this fails, we don't bother trying the shrink the
904 	 *    stripe_heads down again, we just leave them as they are.
905 	 *    As each stripe_head is processed the new one is released into
906 	 *    active service.
907 	 *
908 	 * Once step2 is started, we cannot afford to wait for a write,
909 	 * so we use GFP_NOIO allocations.
910 	 */
911 	struct stripe_head *osh, *nsh;
912 	LIST_HEAD(newstripes);
913 	struct disk_info *ndisks;
914 	int err;
915 	struct kmem_cache *sc;
916 	int i;
917 
918 	if (newsize <= conf->pool_size)
919 		return 0; /* never bother to shrink */
920 
921 	err = md_allow_write(conf->mddev);
922 	if (err)
923 		return err;
924 
925 	/* Step 1 */
926 	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
927 			       sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
928 			       0, 0, NULL);
929 	if (!sc)
930 		return -ENOMEM;
931 
932 	for (i = conf->max_nr_stripes; i; i--) {
933 		nsh = kmem_cache_alloc(sc, GFP_KERNEL);
934 		if (!nsh)
935 			break;
936 
937 		memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
938 
939 		nsh->raid_conf = conf;
940 		spin_lock_init(&nsh->lock);
941 
942 		list_add(&nsh->lru, &newstripes);
943 	}
944 	if (i) {
945 		/* didn't get enough, give up */
946 		while (!list_empty(&newstripes)) {
947 			nsh = list_entry(newstripes.next, struct stripe_head, lru);
948 			list_del(&nsh->lru);
949 			kmem_cache_free(sc, nsh);
950 		}
951 		kmem_cache_destroy(sc);
952 		return -ENOMEM;
953 	}
954 	/* Step 2 - Must use GFP_NOIO now.
955 	 * OK, we have enough stripes, start collecting inactive
956 	 * stripes and copying them over
957 	 */
958 	list_for_each_entry(nsh, &newstripes, lru) {
959 		spin_lock_irq(&conf->device_lock);
960 		wait_event_lock_irq(conf->wait_for_stripe,
961 				    !list_empty(&conf->inactive_list),
962 				    conf->device_lock,
963 				    unplug_slaves(conf->mddev)
964 			);
965 		osh = get_free_stripe(conf);
966 		spin_unlock_irq(&conf->device_lock);
967 		atomic_set(&nsh->count, 1);
968 		for(i=0; i<conf->pool_size; i++)
969 			nsh->dev[i].page = osh->dev[i].page;
970 		for( ; i<newsize; i++)
971 			nsh->dev[i].page = NULL;
972 		kmem_cache_free(conf->slab_cache, osh);
973 	}
974 	kmem_cache_destroy(conf->slab_cache);
975 
976 	/* Step 3.
977 	 * At this point, we are holding all the stripes so the array
978 	 * is completely stalled, so now is a good time to resize
979 	 * conf->disks.
980 	 */
981 	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
982 	if (ndisks) {
983 		for (i=0; i<conf->raid_disks; i++)
984 			ndisks[i] = conf->disks[i];
985 		kfree(conf->disks);
986 		conf->disks = ndisks;
987 	} else
988 		err = -ENOMEM;
989 
990 	/* Step 4, return new stripes to service */
991 	while(!list_empty(&newstripes)) {
992 		nsh = list_entry(newstripes.next, struct stripe_head, lru);
993 		list_del_init(&nsh->lru);
994 		for (i=conf->raid_disks; i < newsize; i++)
995 			if (nsh->dev[i].page == NULL) {
996 				struct page *p = alloc_page(GFP_NOIO);
997 				nsh->dev[i].page = p;
998 				if (!p)
999 					err = -ENOMEM;
1000 			}
1001 		release_stripe(nsh);
1002 	}
1003 	/* critical section pass, GFP_NOIO no longer needed */
1004 
1005 	conf->slab_cache = sc;
1006 	conf->active_name = 1-conf->active_name;
1007 	conf->pool_size = newsize;
1008 	return err;
1009 }
1010 #endif
1011 
1012 static int drop_one_stripe(raid5_conf_t *conf)
1013 {
1014 	struct stripe_head *sh;
1015 
1016 	spin_lock_irq(&conf->device_lock);
1017 	sh = get_free_stripe(conf);
1018 	spin_unlock_irq(&conf->device_lock);
1019 	if (!sh)
1020 		return 0;
1021 	BUG_ON(atomic_read(&sh->count));
1022 	shrink_buffers(sh, conf->pool_size);
1023 	kmem_cache_free(conf->slab_cache, sh);
1024 	atomic_dec(&conf->active_stripes);
1025 	return 1;
1026 }
1027 
1028 static void shrink_stripes(raid5_conf_t *conf)
1029 {
1030 	while (drop_one_stripe(conf))
1031 		;
1032 
1033 	if (conf->slab_cache)
1034 		kmem_cache_destroy(conf->slab_cache);
1035 	conf->slab_cache = NULL;
1036 }
1037 
1038 static void raid5_end_read_request(struct bio * bi, int error)
1039 {
1040  	struct stripe_head *sh = bi->bi_private;
1041 	raid5_conf_t *conf = sh->raid_conf;
1042 	int disks = sh->disks, i;
1043 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1044 	char b[BDEVNAME_SIZE];
1045 	mdk_rdev_t *rdev;
1046 
1047 
1048 	for (i=0 ; i<disks; i++)
1049 		if (bi == &sh->dev[i].req)
1050 			break;
1051 
1052 	pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1053 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
1054 		uptodate);
1055 	if (i == disks) {
1056 		BUG();
1057 		return;
1058 	}
1059 
1060 	if (uptodate) {
1061 		set_bit(R5_UPTODATE, &sh->dev[i].flags);
1062 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1063 			rdev = conf->disks[i].rdev;
1064 			printk_rl(KERN_INFO "raid5:%s: read error corrected"
1065 				  " (%lu sectors at %llu on %s)\n",
1066 				  mdname(conf->mddev), STRIPE_SECTORS,
1067 				  (unsigned long long)(sh->sector
1068 						       + rdev->data_offset),
1069 				  bdevname(rdev->bdev, b));
1070 			clear_bit(R5_ReadError, &sh->dev[i].flags);
1071 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
1072 		}
1073 		if (atomic_read(&conf->disks[i].rdev->read_errors))
1074 			atomic_set(&conf->disks[i].rdev->read_errors, 0);
1075 	} else {
1076 		const char *bdn = bdevname(conf->disks[i].rdev->bdev, b);
1077 		int retry = 0;
1078 		rdev = conf->disks[i].rdev;
1079 
1080 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1081 		atomic_inc(&rdev->read_errors);
1082 		if (conf->mddev->degraded)
1083 			printk_rl(KERN_WARNING
1084 				  "raid5:%s: read error not correctable "
1085 				  "(sector %llu on %s).\n",
1086 				  mdname(conf->mddev),
1087 				  (unsigned long long)(sh->sector
1088 						       + rdev->data_offset),
1089 				  bdn);
1090 		else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
1091 			/* Oh, no!!! */
1092 			printk_rl(KERN_WARNING
1093 				  "raid5:%s: read error NOT corrected!! "
1094 				  "(sector %llu on %s).\n",
1095 				  mdname(conf->mddev),
1096 				  (unsigned long long)(sh->sector
1097 						       + rdev->data_offset),
1098 				  bdn);
1099 		else if (atomic_read(&rdev->read_errors)
1100 			 > conf->max_nr_stripes)
1101 			printk(KERN_WARNING
1102 			       "raid5:%s: Too many read errors, failing device %s.\n",
1103 			       mdname(conf->mddev), bdn);
1104 		else
1105 			retry = 1;
1106 		if (retry)
1107 			set_bit(R5_ReadError, &sh->dev[i].flags);
1108 		else {
1109 			clear_bit(R5_ReadError, &sh->dev[i].flags);
1110 			clear_bit(R5_ReWrite, &sh->dev[i].flags);
1111 			md_error(conf->mddev, rdev);
1112 		}
1113 	}
1114 	rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1115 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
1116 	set_bit(STRIPE_HANDLE, &sh->state);
1117 	release_stripe(sh);
1118 }
1119 
1120 static void raid5_end_write_request (struct bio *bi, int error)
1121 {
1122  	struct stripe_head *sh = bi->bi_private;
1123 	raid5_conf_t *conf = sh->raid_conf;
1124 	int disks = sh->disks, i;
1125 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1126 
1127 	for (i=0 ; i<disks; i++)
1128 		if (bi == &sh->dev[i].req)
1129 			break;
1130 
1131 	pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1132 		(unsigned long long)sh->sector, i, atomic_read(&sh->count),
1133 		uptodate);
1134 	if (i == disks) {
1135 		BUG();
1136 		return;
1137 	}
1138 
1139 	if (!uptodate)
1140 		md_error(conf->mddev, conf->disks[i].rdev);
1141 
1142 	rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1143 
1144 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
1145 	set_bit(STRIPE_HANDLE, &sh->state);
1146 	release_stripe(sh);
1147 }
1148 
1149 
1150 static sector_t compute_blocknr(struct stripe_head *sh, int i);
1151 
1152 static void raid5_build_block (struct stripe_head *sh, int i)
1153 {
1154 	struct r5dev *dev = &sh->dev[i];
1155 
1156 	bio_init(&dev->req);
1157 	dev->req.bi_io_vec = &dev->vec;
1158 	dev->req.bi_vcnt++;
1159 	dev->req.bi_max_vecs++;
1160 	dev->vec.bv_page = dev->page;
1161 	dev->vec.bv_len = STRIPE_SIZE;
1162 	dev->vec.bv_offset = 0;
1163 
1164 	dev->req.bi_sector = sh->sector;
1165 	dev->req.bi_private = sh;
1166 
1167 	dev->flags = 0;
1168 	dev->sector = compute_blocknr(sh, i);
1169 }
1170 
1171 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1172 {
1173 	char b[BDEVNAME_SIZE];
1174 	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1175 	pr_debug("raid5: error called\n");
1176 
1177 	if (!test_bit(Faulty, &rdev->flags)) {
1178 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
1179 		if (test_and_clear_bit(In_sync, &rdev->flags)) {
1180 			unsigned long flags;
1181 			spin_lock_irqsave(&conf->device_lock, flags);
1182 			mddev->degraded++;
1183 			spin_unlock_irqrestore(&conf->device_lock, flags);
1184 			/*
1185 			 * if recovery was running, make sure it aborts.
1186 			 */
1187 			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1188 		}
1189 		set_bit(Faulty, &rdev->flags);
1190 		printk (KERN_ALERT
1191 			"raid5: Disk failure on %s, disabling device.\n"
1192 			"raid5: Operation continuing on %d devices.\n",
1193 			bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
1194 	}
1195 }
1196 
1197 /*
1198  * Input: a 'big' sector number,
1199  * Output: index of the data and parity disk, and the sector # in them.
1200  */
1201 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
1202 			unsigned int data_disks, unsigned int * dd_idx,
1203 			unsigned int * pd_idx, raid5_conf_t *conf)
1204 {
1205 	long stripe;
1206 	unsigned long chunk_number;
1207 	unsigned int chunk_offset;
1208 	sector_t new_sector;
1209 	int sectors_per_chunk = conf->chunk_size >> 9;
1210 
1211 	/* First compute the information on this sector */
1212 
1213 	/*
1214 	 * Compute the chunk number and the sector offset inside the chunk
1215 	 */
1216 	chunk_offset = sector_div(r_sector, sectors_per_chunk);
1217 	chunk_number = r_sector;
1218 	BUG_ON(r_sector != chunk_number);
1219 
1220 	/*
1221 	 * Compute the stripe number
1222 	 */
1223 	stripe = chunk_number / data_disks;
1224 
1225 	/*
1226 	 * Compute the data disk and parity disk indexes inside the stripe
1227 	 */
1228 	*dd_idx = chunk_number % data_disks;
1229 
1230 	/*
1231 	 * Select the parity disk based on the user selected algorithm.
1232 	 */
1233 	switch(conf->level) {
1234 	case 4:
1235 		*pd_idx = data_disks;
1236 		break;
1237 	case 5:
1238 		switch (conf->algorithm) {
1239 		case ALGORITHM_LEFT_ASYMMETRIC:
1240 			*pd_idx = data_disks - stripe % raid_disks;
1241 			if (*dd_idx >= *pd_idx)
1242 				(*dd_idx)++;
1243 			break;
1244 		case ALGORITHM_RIGHT_ASYMMETRIC:
1245 			*pd_idx = stripe % raid_disks;
1246 			if (*dd_idx >= *pd_idx)
1247 				(*dd_idx)++;
1248 			break;
1249 		case ALGORITHM_LEFT_SYMMETRIC:
1250 			*pd_idx = data_disks - stripe % raid_disks;
1251 			*dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1252 			break;
1253 		case ALGORITHM_RIGHT_SYMMETRIC:
1254 			*pd_idx = stripe % raid_disks;
1255 			*dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1256 			break;
1257 		default:
1258 			printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1259 				conf->algorithm);
1260 		}
1261 		break;
1262 	case 6:
1263 
1264 		/**** FIX THIS ****/
1265 		switch (conf->algorithm) {
1266 		case ALGORITHM_LEFT_ASYMMETRIC:
1267 			*pd_idx = raid_disks - 1 - (stripe % raid_disks);
1268 			if (*pd_idx == raid_disks-1)
1269 				(*dd_idx)++; 	/* Q D D D P */
1270 			else if (*dd_idx >= *pd_idx)
1271 				(*dd_idx) += 2; /* D D P Q D */
1272 			break;
1273 		case ALGORITHM_RIGHT_ASYMMETRIC:
1274 			*pd_idx = stripe % raid_disks;
1275 			if (*pd_idx == raid_disks-1)
1276 				(*dd_idx)++; 	/* Q D D D P */
1277 			else if (*dd_idx >= *pd_idx)
1278 				(*dd_idx) += 2; /* D D P Q D */
1279 			break;
1280 		case ALGORITHM_LEFT_SYMMETRIC:
1281 			*pd_idx = raid_disks - 1 - (stripe % raid_disks);
1282 			*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1283 			break;
1284 		case ALGORITHM_RIGHT_SYMMETRIC:
1285 			*pd_idx = stripe % raid_disks;
1286 			*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1287 			break;
1288 		default:
1289 			printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1290 				conf->algorithm);
1291 		}
1292 		break;
1293 	}
1294 
1295 	/*
1296 	 * Finally, compute the new sector number
1297 	 */
1298 	new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
1299 	return new_sector;
1300 }
1301 
1302 
1303 static sector_t compute_blocknr(struct stripe_head *sh, int i)
1304 {
1305 	raid5_conf_t *conf = sh->raid_conf;
1306 	int raid_disks = sh->disks;
1307 	int data_disks = raid_disks - conf->max_degraded;
1308 	sector_t new_sector = sh->sector, check;
1309 	int sectors_per_chunk = conf->chunk_size >> 9;
1310 	sector_t stripe;
1311 	int chunk_offset;
1312 	int chunk_number, dummy1, dummy2, dd_idx = i;
1313 	sector_t r_sector;
1314 
1315 
1316 	chunk_offset = sector_div(new_sector, sectors_per_chunk);
1317 	stripe = new_sector;
1318 	BUG_ON(new_sector != stripe);
1319 
1320 	if (i == sh->pd_idx)
1321 		return 0;
1322 	switch(conf->level) {
1323 	case 4: break;
1324 	case 5:
1325 		switch (conf->algorithm) {
1326 		case ALGORITHM_LEFT_ASYMMETRIC:
1327 		case ALGORITHM_RIGHT_ASYMMETRIC:
1328 			if (i > sh->pd_idx)
1329 				i--;
1330 			break;
1331 		case ALGORITHM_LEFT_SYMMETRIC:
1332 		case ALGORITHM_RIGHT_SYMMETRIC:
1333 			if (i < sh->pd_idx)
1334 				i += raid_disks;
1335 			i -= (sh->pd_idx + 1);
1336 			break;
1337 		default:
1338 			printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1339 			       conf->algorithm);
1340 		}
1341 		break;
1342 	case 6:
1343 		if (i == raid6_next_disk(sh->pd_idx, raid_disks))
1344 			return 0; /* It is the Q disk */
1345 		switch (conf->algorithm) {
1346 		case ALGORITHM_LEFT_ASYMMETRIC:
1347 		case ALGORITHM_RIGHT_ASYMMETRIC:
1348 		  	if (sh->pd_idx == raid_disks-1)
1349 				i--; 	/* Q D D D P */
1350 			else if (i > sh->pd_idx)
1351 				i -= 2; /* D D P Q D */
1352 			break;
1353 		case ALGORITHM_LEFT_SYMMETRIC:
1354 		case ALGORITHM_RIGHT_SYMMETRIC:
1355 			if (sh->pd_idx == raid_disks-1)
1356 				i--; /* Q D D D P */
1357 			else {
1358 				/* D D P Q D */
1359 				if (i < sh->pd_idx)
1360 					i += raid_disks;
1361 				i -= (sh->pd_idx + 2);
1362 			}
1363 			break;
1364 		default:
1365 			printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1366 				conf->algorithm);
1367 		}
1368 		break;
1369 	}
1370 
1371 	chunk_number = stripe * data_disks + i;
1372 	r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
1373 
1374 	check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
1375 	if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
1376 		printk(KERN_ERR "compute_blocknr: map not correct\n");
1377 		return 0;
1378 	}
1379 	return r_sector;
1380 }
1381 
1382 
1383 
1384 /*
1385  * Copy data between a page in the stripe cache, and one or more bion
1386  * The page could align with the middle of the bio, or there could be
1387  * several bion, each with several bio_vecs, which cover part of the page
1388  * Multiple bion are linked together on bi_next.  There may be extras
1389  * at the end of this list.  We ignore them.
1390  */
1391 static void copy_data(int frombio, struct bio *bio,
1392 		     struct page *page,
1393 		     sector_t sector)
1394 {
1395 	char *pa = page_address(page);
1396 	struct bio_vec *bvl;
1397 	int i;
1398 	int page_offset;
1399 
1400 	if (bio->bi_sector >= sector)
1401 		page_offset = (signed)(bio->bi_sector - sector) * 512;
1402 	else
1403 		page_offset = (signed)(sector - bio->bi_sector) * -512;
1404 	bio_for_each_segment(bvl, bio, i) {
1405 		int len = bio_iovec_idx(bio,i)->bv_len;
1406 		int clen;
1407 		int b_offset = 0;
1408 
1409 		if (page_offset < 0) {
1410 			b_offset = -page_offset;
1411 			page_offset += b_offset;
1412 			len -= b_offset;
1413 		}
1414 
1415 		if (len > 0 && page_offset + len > STRIPE_SIZE)
1416 			clen = STRIPE_SIZE - page_offset;
1417 		else clen = len;
1418 
1419 		if (clen > 0) {
1420 			char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
1421 			if (frombio)
1422 				memcpy(pa+page_offset, ba+b_offset, clen);
1423 			else
1424 				memcpy(ba+b_offset, pa+page_offset, clen);
1425 			__bio_kunmap_atomic(ba, KM_USER0);
1426 		}
1427 		if (clen < len) /* hit end of page */
1428 			break;
1429 		page_offset +=  len;
1430 	}
1431 }
1432 
1433 #define check_xor()	do {						  \
1434 				if (count == MAX_XOR_BLOCKS) {		  \
1435 				xor_blocks(count, STRIPE_SIZE, dest, ptr);\
1436 				count = 0;				  \
1437 			   }						  \
1438 			} while(0)
1439 
1440 static void compute_parity6(struct stripe_head *sh, int method)
1441 {
1442 	raid6_conf_t *conf = sh->raid_conf;
1443 	int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
1444 	struct bio *chosen;
1445 	/**** FIX THIS: This could be very bad if disks is close to 256 ****/
1446 	void *ptrs[disks];
1447 
1448 	qd_idx = raid6_next_disk(pd_idx, disks);
1449 	d0_idx = raid6_next_disk(qd_idx, disks);
1450 
1451 	pr_debug("compute_parity, stripe %llu, method %d\n",
1452 		(unsigned long long)sh->sector, method);
1453 
1454 	switch(method) {
1455 	case READ_MODIFY_WRITE:
1456 		BUG();		/* READ_MODIFY_WRITE N/A for RAID-6 */
1457 	case RECONSTRUCT_WRITE:
1458 		for (i= disks; i-- ;)
1459 			if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
1460 				chosen = sh->dev[i].towrite;
1461 				sh->dev[i].towrite = NULL;
1462 
1463 				if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1464 					wake_up(&conf->wait_for_overlap);
1465 
1466 				BUG_ON(sh->dev[i].written);
1467 				sh->dev[i].written = chosen;
1468 			}
1469 		break;
1470 	case CHECK_PARITY:
1471 		BUG();		/* Not implemented yet */
1472 	}
1473 
1474 	for (i = disks; i--;)
1475 		if (sh->dev[i].written) {
1476 			sector_t sector = sh->dev[i].sector;
1477 			struct bio *wbi = sh->dev[i].written;
1478 			while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1479 				copy_data(1, wbi, sh->dev[i].page, sector);
1480 				wbi = r5_next_bio(wbi, sector);
1481 			}
1482 
1483 			set_bit(R5_LOCKED, &sh->dev[i].flags);
1484 			set_bit(R5_UPTODATE, &sh->dev[i].flags);
1485 		}
1486 
1487 //	switch(method) {
1488 //	case RECONSTRUCT_WRITE:
1489 //	case CHECK_PARITY:
1490 //	case UPDATE_PARITY:
1491 		/* Note that unlike RAID-5, the ordering of the disks matters greatly. */
1492 		/* FIX: Is this ordering of drives even remotely optimal? */
1493 		count = 0;
1494 		i = d0_idx;
1495 		do {
1496 			ptrs[count++] = page_address(sh->dev[i].page);
1497 			if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1498 				printk("block %d/%d not uptodate on parity calc\n", i,count);
1499 			i = raid6_next_disk(i, disks);
1500 		} while ( i != d0_idx );
1501 //		break;
1502 //	}
1503 
1504 	raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
1505 
1506 	switch(method) {
1507 	case RECONSTRUCT_WRITE:
1508 		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1509 		set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1510 		set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1511 		set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
1512 		break;
1513 	case UPDATE_PARITY:
1514 		set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1515 		set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1516 		break;
1517 	}
1518 }
1519 
1520 
1521 /* Compute one missing block */
1522 static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
1523 {
1524 	int i, count, disks = sh->disks;
1525 	void *ptr[MAX_XOR_BLOCKS], *dest, *p;
1526 	int pd_idx = sh->pd_idx;
1527 	int qd_idx = raid6_next_disk(pd_idx, disks);
1528 
1529 	pr_debug("compute_block_1, stripe %llu, idx %d\n",
1530 		(unsigned long long)sh->sector, dd_idx);
1531 
1532 	if ( dd_idx == qd_idx ) {
1533 		/* We're actually computing the Q drive */
1534 		compute_parity6(sh, UPDATE_PARITY);
1535 	} else {
1536 		dest = page_address(sh->dev[dd_idx].page);
1537 		if (!nozero) memset(dest, 0, STRIPE_SIZE);
1538 		count = 0;
1539 		for (i = disks ; i--; ) {
1540 			if (i == dd_idx || i == qd_idx)
1541 				continue;
1542 			p = page_address(sh->dev[i].page);
1543 			if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
1544 				ptr[count++] = p;
1545 			else
1546 				printk("compute_block() %d, stripe %llu, %d"
1547 				       " not present\n", dd_idx,
1548 				       (unsigned long long)sh->sector, i);
1549 
1550 			check_xor();
1551 		}
1552 		if (count)
1553 			xor_blocks(count, STRIPE_SIZE, dest, ptr);
1554 		if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1555 		else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1556 	}
1557 }
1558 
1559 /* Compute two missing blocks */
1560 static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
1561 {
1562 	int i, count, disks = sh->disks;
1563 	int pd_idx = sh->pd_idx;
1564 	int qd_idx = raid6_next_disk(pd_idx, disks);
1565 	int d0_idx = raid6_next_disk(qd_idx, disks);
1566 	int faila, failb;
1567 
1568 	/* faila and failb are disk numbers relative to d0_idx */
1569 	/* pd_idx become disks-2 and qd_idx become disks-1 */
1570 	faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
1571 	failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
1572 
1573 	BUG_ON(faila == failb);
1574 	if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
1575 
1576 	pr_debug("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
1577 	       (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
1578 
1579 	if ( failb == disks-1 ) {
1580 		/* Q disk is one of the missing disks */
1581 		if ( faila == disks-2 ) {
1582 			/* Missing P+Q, just recompute */
1583 			compute_parity6(sh, UPDATE_PARITY);
1584 			return;
1585 		} else {
1586 			/* We're missing D+Q; recompute D from P */
1587 			compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
1588 			compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
1589 			return;
1590 		}
1591 	}
1592 
1593 	/* We're missing D+P or D+D; build pointer table */
1594 	{
1595 		/**** FIX THIS: This could be very bad if disks is close to 256 ****/
1596 		void *ptrs[disks];
1597 
1598 		count = 0;
1599 		i = d0_idx;
1600 		do {
1601 			ptrs[count++] = page_address(sh->dev[i].page);
1602 			i = raid6_next_disk(i, disks);
1603 			if (i != dd_idx1 && i != dd_idx2 &&
1604 			    !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1605 				printk("compute_2 with missing block %d/%d\n", count, i);
1606 		} while ( i != d0_idx );
1607 
1608 		if ( failb == disks-2 ) {
1609 			/* We're missing D+P. */
1610 			raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
1611 		} else {
1612 			/* We're missing D+D. */
1613 			raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
1614 		}
1615 
1616 		/* Both the above update both missing blocks */
1617 		set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
1618 		set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
1619 	}
1620 }
1621 
1622 static void
1623 schedule_reconstruction5(struct stripe_head *sh, struct stripe_head_state *s,
1624 			 int rcw, int expand)
1625 {
1626 	int i, pd_idx = sh->pd_idx, disks = sh->disks;
1627 
1628 	if (rcw) {
1629 		/* if we are not expanding this is a proper write request, and
1630 		 * there will be bios with new data to be drained into the
1631 		 * stripe cache
1632 		 */
1633 		if (!expand) {
1634 			sh->reconstruct_state = reconstruct_state_drain_run;
1635 			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
1636 		} else
1637 			sh->reconstruct_state = reconstruct_state_run;
1638 
1639 		set_bit(STRIPE_OP_POSTXOR, &s->ops_request);
1640 
1641 		for (i = disks; i--; ) {
1642 			struct r5dev *dev = &sh->dev[i];
1643 
1644 			if (dev->towrite) {
1645 				set_bit(R5_LOCKED, &dev->flags);
1646 				set_bit(R5_Wantdrain, &dev->flags);
1647 				if (!expand)
1648 					clear_bit(R5_UPTODATE, &dev->flags);
1649 				s->locked++;
1650 			}
1651 		}
1652 		if (s->locked + 1 == disks)
1653 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
1654 				atomic_inc(&sh->raid_conf->pending_full_writes);
1655 	} else {
1656 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
1657 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
1658 
1659 		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
1660 		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
1661 		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
1662 		set_bit(STRIPE_OP_POSTXOR, &s->ops_request);
1663 
1664 		for (i = disks; i--; ) {
1665 			struct r5dev *dev = &sh->dev[i];
1666 			if (i == pd_idx)
1667 				continue;
1668 
1669 			if (dev->towrite &&
1670 			    (test_bit(R5_UPTODATE, &dev->flags) ||
1671 			     test_bit(R5_Wantcompute, &dev->flags))) {
1672 				set_bit(R5_Wantdrain, &dev->flags);
1673 				set_bit(R5_LOCKED, &dev->flags);
1674 				clear_bit(R5_UPTODATE, &dev->flags);
1675 				s->locked++;
1676 			}
1677 		}
1678 	}
1679 
1680 	/* keep the parity disk locked while asynchronous operations
1681 	 * are in flight
1682 	 */
1683 	set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
1684 	clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1685 	s->locked++;
1686 
1687 	pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
1688 		__func__, (unsigned long long)sh->sector,
1689 		s->locked, s->ops_request);
1690 }
1691 
1692 /*
1693  * Each stripe/dev can have one or more bion attached.
1694  * toread/towrite point to the first in a chain.
1695  * The bi_next chain must be in order.
1696  */
1697 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
1698 {
1699 	struct bio **bip;
1700 	raid5_conf_t *conf = sh->raid_conf;
1701 	int firstwrite=0;
1702 
1703 	pr_debug("adding bh b#%llu to stripe s#%llu\n",
1704 		(unsigned long long)bi->bi_sector,
1705 		(unsigned long long)sh->sector);
1706 
1707 
1708 	spin_lock(&sh->lock);
1709 	spin_lock_irq(&conf->device_lock);
1710 	if (forwrite) {
1711 		bip = &sh->dev[dd_idx].towrite;
1712 		if (*bip == NULL && sh->dev[dd_idx].written == NULL)
1713 			firstwrite = 1;
1714 	} else
1715 		bip = &sh->dev[dd_idx].toread;
1716 	while (*bip && (*bip)->bi_sector < bi->bi_sector) {
1717 		if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
1718 			goto overlap;
1719 		bip = & (*bip)->bi_next;
1720 	}
1721 	if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
1722 		goto overlap;
1723 
1724 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
1725 	if (*bip)
1726 		bi->bi_next = *bip;
1727 	*bip = bi;
1728 	bi->bi_phys_segments ++;
1729 	spin_unlock_irq(&conf->device_lock);
1730 	spin_unlock(&sh->lock);
1731 
1732 	pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
1733 		(unsigned long long)bi->bi_sector,
1734 		(unsigned long long)sh->sector, dd_idx);
1735 
1736 	if (conf->mddev->bitmap && firstwrite) {
1737 		bitmap_startwrite(conf->mddev->bitmap, sh->sector,
1738 				  STRIPE_SECTORS, 0);
1739 		sh->bm_seq = conf->seq_flush+1;
1740 		set_bit(STRIPE_BIT_DELAY, &sh->state);
1741 	}
1742 
1743 	if (forwrite) {
1744 		/* check if page is covered */
1745 		sector_t sector = sh->dev[dd_idx].sector;
1746 		for (bi=sh->dev[dd_idx].towrite;
1747 		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
1748 			     bi && bi->bi_sector <= sector;
1749 		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
1750 			if (bi->bi_sector + (bi->bi_size>>9) >= sector)
1751 				sector = bi->bi_sector + (bi->bi_size>>9);
1752 		}
1753 		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
1754 			set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
1755 	}
1756 	return 1;
1757 
1758  overlap:
1759 	set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1760 	spin_unlock_irq(&conf->device_lock);
1761 	spin_unlock(&sh->lock);
1762 	return 0;
1763 }
1764 
1765 static void end_reshape(raid5_conf_t *conf);
1766 
1767 static int page_is_zero(struct page *p)
1768 {
1769 	char *a = page_address(p);
1770 	return ((*(u32*)a) == 0 &&
1771 		memcmp(a, a+4, STRIPE_SIZE-4)==0);
1772 }
1773 
1774 static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
1775 {
1776 	int sectors_per_chunk = conf->chunk_size >> 9;
1777 	int pd_idx, dd_idx;
1778 	int chunk_offset = sector_div(stripe, sectors_per_chunk);
1779 
1780 	raid5_compute_sector(stripe * (disks - conf->max_degraded)
1781 			     *sectors_per_chunk + chunk_offset,
1782 			     disks, disks - conf->max_degraded,
1783 			     &dd_idx, &pd_idx, conf);
1784 	return pd_idx;
1785 }
1786 
1787 static void
1788 handle_failed_stripe(raid5_conf_t *conf, struct stripe_head *sh,
1789 				struct stripe_head_state *s, int disks,
1790 				struct bio **return_bi)
1791 {
1792 	int i;
1793 	for (i = disks; i--; ) {
1794 		struct bio *bi;
1795 		int bitmap_end = 0;
1796 
1797 		if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1798 			mdk_rdev_t *rdev;
1799 			rcu_read_lock();
1800 			rdev = rcu_dereference(conf->disks[i].rdev);
1801 			if (rdev && test_bit(In_sync, &rdev->flags))
1802 				/* multiple read failures in one stripe */
1803 				md_error(conf->mddev, rdev);
1804 			rcu_read_unlock();
1805 		}
1806 		spin_lock_irq(&conf->device_lock);
1807 		/* fail all writes first */
1808 		bi = sh->dev[i].towrite;
1809 		sh->dev[i].towrite = NULL;
1810 		if (bi) {
1811 			s->to_write--;
1812 			bitmap_end = 1;
1813 		}
1814 
1815 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1816 			wake_up(&conf->wait_for_overlap);
1817 
1818 		while (bi && bi->bi_sector <
1819 			sh->dev[i].sector + STRIPE_SECTORS) {
1820 			struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1821 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
1822 			if (--bi->bi_phys_segments == 0) {
1823 				md_write_end(conf->mddev);
1824 				bi->bi_next = *return_bi;
1825 				*return_bi = bi;
1826 			}
1827 			bi = nextbi;
1828 		}
1829 		/* and fail all 'written' */
1830 		bi = sh->dev[i].written;
1831 		sh->dev[i].written = NULL;
1832 		if (bi) bitmap_end = 1;
1833 		while (bi && bi->bi_sector <
1834 		       sh->dev[i].sector + STRIPE_SECTORS) {
1835 			struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1836 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
1837 			if (--bi->bi_phys_segments == 0) {
1838 				md_write_end(conf->mddev);
1839 				bi->bi_next = *return_bi;
1840 				*return_bi = bi;
1841 			}
1842 			bi = bi2;
1843 		}
1844 
1845 		/* fail any reads if this device is non-operational and
1846 		 * the data has not reached the cache yet.
1847 		 */
1848 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
1849 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1850 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
1851 			bi = sh->dev[i].toread;
1852 			sh->dev[i].toread = NULL;
1853 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1854 				wake_up(&conf->wait_for_overlap);
1855 			if (bi) s->to_read--;
1856 			while (bi && bi->bi_sector <
1857 			       sh->dev[i].sector + STRIPE_SECTORS) {
1858 				struct bio *nextbi =
1859 					r5_next_bio(bi, sh->dev[i].sector);
1860 				clear_bit(BIO_UPTODATE, &bi->bi_flags);
1861 				if (--bi->bi_phys_segments == 0) {
1862 					bi->bi_next = *return_bi;
1863 					*return_bi = bi;
1864 				}
1865 				bi = nextbi;
1866 			}
1867 		}
1868 		spin_unlock_irq(&conf->device_lock);
1869 		if (bitmap_end)
1870 			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1871 					STRIPE_SECTORS, 0, 0);
1872 	}
1873 
1874 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
1875 		if (atomic_dec_and_test(&conf->pending_full_writes))
1876 			md_wakeup_thread(conf->mddev->thread);
1877 }
1878 
1879 /* fetch_block5 - checks the given member device to see if its data needs
1880  * to be read or computed to satisfy a request.
1881  *
1882  * Returns 1 when no more member devices need to be checked, otherwise returns
1883  * 0 to tell the loop in handle_stripe_fill5 to continue
1884  */
1885 static int fetch_block5(struct stripe_head *sh, struct stripe_head_state *s,
1886 			int disk_idx, int disks)
1887 {
1888 	struct r5dev *dev = &sh->dev[disk_idx];
1889 	struct r5dev *failed_dev = &sh->dev[s->failed_num];
1890 
1891 	/* is the data in this block needed, and can we get it? */
1892 	if (!test_bit(R5_LOCKED, &dev->flags) &&
1893 	    !test_bit(R5_UPTODATE, &dev->flags) &&
1894 	    (dev->toread ||
1895 	     (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1896 	     s->syncing || s->expanding ||
1897 	     (s->failed &&
1898 	      (failed_dev->toread ||
1899 	       (failed_dev->towrite &&
1900 		!test_bit(R5_OVERWRITE, &failed_dev->flags)))))) {
1901 		/* We would like to get this block, possibly by computing it,
1902 		 * otherwise read it if the backing disk is insync
1903 		 */
1904 		if ((s->uptodate == disks - 1) &&
1905 		    (s->failed && disk_idx == s->failed_num)) {
1906 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
1907 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
1908 			set_bit(R5_Wantcompute, &dev->flags);
1909 			sh->ops.target = disk_idx;
1910 			s->req_compute = 1;
1911 			/* Careful: from this point on 'uptodate' is in the eye
1912 			 * of raid5_run_ops which services 'compute' operations
1913 			 * before writes. R5_Wantcompute flags a block that will
1914 			 * be R5_UPTODATE by the time it is needed for a
1915 			 * subsequent operation.
1916 			 */
1917 			s->uptodate++;
1918 			return 1; /* uptodate + compute == disks */
1919 		} else if (test_bit(R5_Insync, &dev->flags)) {
1920 			set_bit(R5_LOCKED, &dev->flags);
1921 			set_bit(R5_Wantread, &dev->flags);
1922 			s->locked++;
1923 			pr_debug("Reading block %d (sync=%d)\n", disk_idx,
1924 				s->syncing);
1925 		}
1926 	}
1927 
1928 	return 0;
1929 }
1930 
1931 /**
1932  * handle_stripe_fill5 - read or compute data to satisfy pending requests.
1933  */
1934 static void handle_stripe_fill5(struct stripe_head *sh,
1935 			struct stripe_head_state *s, int disks)
1936 {
1937 	int i;
1938 
1939 	/* look for blocks to read/compute, skip this if a compute
1940 	 * is already in flight, or if the stripe contents are in the
1941 	 * midst of changing due to a write
1942 	 */
1943 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
1944 	    !sh->reconstruct_state)
1945 		for (i = disks; i--; )
1946 			if (fetch_block5(sh, s, i, disks))
1947 				break;
1948 	set_bit(STRIPE_HANDLE, &sh->state);
1949 }
1950 
1951 static void handle_stripe_fill6(struct stripe_head *sh,
1952 			struct stripe_head_state *s, struct r6_state *r6s,
1953 			int disks)
1954 {
1955 	int i;
1956 	for (i = disks; i--; ) {
1957 		struct r5dev *dev = &sh->dev[i];
1958 		if (!test_bit(R5_LOCKED, &dev->flags) &&
1959 		    !test_bit(R5_UPTODATE, &dev->flags) &&
1960 		    (dev->toread || (dev->towrite &&
1961 		     !test_bit(R5_OVERWRITE, &dev->flags)) ||
1962 		     s->syncing || s->expanding ||
1963 		     (s->failed >= 1 &&
1964 		      (sh->dev[r6s->failed_num[0]].toread ||
1965 		       s->to_write)) ||
1966 		     (s->failed >= 2 &&
1967 		      (sh->dev[r6s->failed_num[1]].toread ||
1968 		       s->to_write)))) {
1969 			/* we would like to get this block, possibly
1970 			 * by computing it, but we might not be able to
1971 			 */
1972 			if ((s->uptodate == disks - 1) &&
1973 			    (s->failed && (i == r6s->failed_num[0] ||
1974 					   i == r6s->failed_num[1]))) {
1975 				pr_debug("Computing stripe %llu block %d\n",
1976 				       (unsigned long long)sh->sector, i);
1977 				compute_block_1(sh, i, 0);
1978 				s->uptodate++;
1979 			} else if ( s->uptodate == disks-2 && s->failed >= 2 ) {
1980 				/* Computing 2-failure is *very* expensive; only
1981 				 * do it if failed >= 2
1982 				 */
1983 				int other;
1984 				for (other = disks; other--; ) {
1985 					if (other == i)
1986 						continue;
1987 					if (!test_bit(R5_UPTODATE,
1988 					      &sh->dev[other].flags))
1989 						break;
1990 				}
1991 				BUG_ON(other < 0);
1992 				pr_debug("Computing stripe %llu blocks %d,%d\n",
1993 				       (unsigned long long)sh->sector,
1994 				       i, other);
1995 				compute_block_2(sh, i, other);
1996 				s->uptodate += 2;
1997 			} else if (test_bit(R5_Insync, &dev->flags)) {
1998 				set_bit(R5_LOCKED, &dev->flags);
1999 				set_bit(R5_Wantread, &dev->flags);
2000 				s->locked++;
2001 				pr_debug("Reading block %d (sync=%d)\n",
2002 					i, s->syncing);
2003 			}
2004 		}
2005 	}
2006 	set_bit(STRIPE_HANDLE, &sh->state);
2007 }
2008 
2009 
2010 /* handle_stripe_clean_event
2011  * any written block on an uptodate or failed drive can be returned.
2012  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2013  * never LOCKED, so we don't need to test 'failed' directly.
2014  */
2015 static void handle_stripe_clean_event(raid5_conf_t *conf,
2016 	struct stripe_head *sh, int disks, struct bio **return_bi)
2017 {
2018 	int i;
2019 	struct r5dev *dev;
2020 
2021 	for (i = disks; i--; )
2022 		if (sh->dev[i].written) {
2023 			dev = &sh->dev[i];
2024 			if (!test_bit(R5_LOCKED, &dev->flags) &&
2025 				test_bit(R5_UPTODATE, &dev->flags)) {
2026 				/* We can return any write requests */
2027 				struct bio *wbi, *wbi2;
2028 				int bitmap_end = 0;
2029 				pr_debug("Return write for disc %d\n", i);
2030 				spin_lock_irq(&conf->device_lock);
2031 				wbi = dev->written;
2032 				dev->written = NULL;
2033 				while (wbi && wbi->bi_sector <
2034 					dev->sector + STRIPE_SECTORS) {
2035 					wbi2 = r5_next_bio(wbi, dev->sector);
2036 					if (--wbi->bi_phys_segments == 0) {
2037 						md_write_end(conf->mddev);
2038 						wbi->bi_next = *return_bi;
2039 						*return_bi = wbi;
2040 					}
2041 					wbi = wbi2;
2042 				}
2043 				if (dev->towrite == NULL)
2044 					bitmap_end = 1;
2045 				spin_unlock_irq(&conf->device_lock);
2046 				if (bitmap_end)
2047 					bitmap_endwrite(conf->mddev->bitmap,
2048 							sh->sector,
2049 							STRIPE_SECTORS,
2050 					 !test_bit(STRIPE_DEGRADED, &sh->state),
2051 							0);
2052 			}
2053 		}
2054 
2055 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2056 		if (atomic_dec_and_test(&conf->pending_full_writes))
2057 			md_wakeup_thread(conf->mddev->thread);
2058 }
2059 
2060 static void handle_stripe_dirtying5(raid5_conf_t *conf,
2061 		struct stripe_head *sh,	struct stripe_head_state *s, int disks)
2062 {
2063 	int rmw = 0, rcw = 0, i;
2064 	for (i = disks; i--; ) {
2065 		/* would I have to read this buffer for read_modify_write */
2066 		struct r5dev *dev = &sh->dev[i];
2067 		if ((dev->towrite || i == sh->pd_idx) &&
2068 		    !test_bit(R5_LOCKED, &dev->flags) &&
2069 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
2070 		      test_bit(R5_Wantcompute, &dev->flags))) {
2071 			if (test_bit(R5_Insync, &dev->flags))
2072 				rmw++;
2073 			else
2074 				rmw += 2*disks;  /* cannot read it */
2075 		}
2076 		/* Would I have to read this buffer for reconstruct_write */
2077 		if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2078 		    !test_bit(R5_LOCKED, &dev->flags) &&
2079 		    !(test_bit(R5_UPTODATE, &dev->flags) ||
2080 		    test_bit(R5_Wantcompute, &dev->flags))) {
2081 			if (test_bit(R5_Insync, &dev->flags)) rcw++;
2082 			else
2083 				rcw += 2*disks;
2084 		}
2085 	}
2086 	pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2087 		(unsigned long long)sh->sector, rmw, rcw);
2088 	set_bit(STRIPE_HANDLE, &sh->state);
2089 	if (rmw < rcw && rmw > 0)
2090 		/* prefer read-modify-write, but need to get some data */
2091 		for (i = disks; i--; ) {
2092 			struct r5dev *dev = &sh->dev[i];
2093 			if ((dev->towrite || i == sh->pd_idx) &&
2094 			    !test_bit(R5_LOCKED, &dev->flags) &&
2095 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
2096 			    test_bit(R5_Wantcompute, &dev->flags)) &&
2097 			    test_bit(R5_Insync, &dev->flags)) {
2098 				if (
2099 				  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2100 					pr_debug("Read_old block "
2101 						"%d for r-m-w\n", i);
2102 					set_bit(R5_LOCKED, &dev->flags);
2103 					set_bit(R5_Wantread, &dev->flags);
2104 					s->locked++;
2105 				} else {
2106 					set_bit(STRIPE_DELAYED, &sh->state);
2107 					set_bit(STRIPE_HANDLE, &sh->state);
2108 				}
2109 			}
2110 		}
2111 	if (rcw <= rmw && rcw > 0)
2112 		/* want reconstruct write, but need to get some data */
2113 		for (i = disks; i--; ) {
2114 			struct r5dev *dev = &sh->dev[i];
2115 			if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2116 			    i != sh->pd_idx &&
2117 			    !test_bit(R5_LOCKED, &dev->flags) &&
2118 			    !(test_bit(R5_UPTODATE, &dev->flags) ||
2119 			    test_bit(R5_Wantcompute, &dev->flags)) &&
2120 			    test_bit(R5_Insync, &dev->flags)) {
2121 				if (
2122 				  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2123 					pr_debug("Read_old block "
2124 						"%d for Reconstruct\n", i);
2125 					set_bit(R5_LOCKED, &dev->flags);
2126 					set_bit(R5_Wantread, &dev->flags);
2127 					s->locked++;
2128 				} else {
2129 					set_bit(STRIPE_DELAYED, &sh->state);
2130 					set_bit(STRIPE_HANDLE, &sh->state);
2131 				}
2132 			}
2133 		}
2134 	/* now if nothing is locked, and if we have enough data,
2135 	 * we can start a write request
2136 	 */
2137 	/* since handle_stripe can be called at any time we need to handle the
2138 	 * case where a compute block operation has been submitted and then a
2139 	 * subsequent call wants to start a write request.  raid5_run_ops only
2140 	 * handles the case where compute block and postxor are requested
2141 	 * simultaneously.  If this is not the case then new writes need to be
2142 	 * held off until the compute completes.
2143 	 */
2144 	if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2145 	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2146 	    !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2147 		schedule_reconstruction5(sh, s, rcw == 0, 0);
2148 }
2149 
2150 static void handle_stripe_dirtying6(raid5_conf_t *conf,
2151 		struct stripe_head *sh,	struct stripe_head_state *s,
2152 		struct r6_state *r6s, int disks)
2153 {
2154 	int rcw = 0, must_compute = 0, pd_idx = sh->pd_idx, i;
2155 	int qd_idx = r6s->qd_idx;
2156 	for (i = disks; i--; ) {
2157 		struct r5dev *dev = &sh->dev[i];
2158 		/* Would I have to read this buffer for reconstruct_write */
2159 		if (!test_bit(R5_OVERWRITE, &dev->flags)
2160 		    && i != pd_idx && i != qd_idx
2161 		    && (!test_bit(R5_LOCKED, &dev->flags)
2162 			    ) &&
2163 		    !test_bit(R5_UPTODATE, &dev->flags)) {
2164 			if (test_bit(R5_Insync, &dev->flags)) rcw++;
2165 			else {
2166 				pr_debug("raid6: must_compute: "
2167 					"disk %d flags=%#lx\n", i, dev->flags);
2168 				must_compute++;
2169 			}
2170 		}
2171 	}
2172 	pr_debug("for sector %llu, rcw=%d, must_compute=%d\n",
2173 	       (unsigned long long)sh->sector, rcw, must_compute);
2174 	set_bit(STRIPE_HANDLE, &sh->state);
2175 
2176 	if (rcw > 0)
2177 		/* want reconstruct write, but need to get some data */
2178 		for (i = disks; i--; ) {
2179 			struct r5dev *dev = &sh->dev[i];
2180 			if (!test_bit(R5_OVERWRITE, &dev->flags)
2181 			    && !(s->failed == 0 && (i == pd_idx || i == qd_idx))
2182 			    && !test_bit(R5_LOCKED, &dev->flags) &&
2183 			    !test_bit(R5_UPTODATE, &dev->flags) &&
2184 			    test_bit(R5_Insync, &dev->flags)) {
2185 				if (
2186 				  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2187 					pr_debug("Read_old stripe %llu "
2188 						"block %d for Reconstruct\n",
2189 					     (unsigned long long)sh->sector, i);
2190 					set_bit(R5_LOCKED, &dev->flags);
2191 					set_bit(R5_Wantread, &dev->flags);
2192 					s->locked++;
2193 				} else {
2194 					pr_debug("Request delayed stripe %llu "
2195 						"block %d for Reconstruct\n",
2196 					     (unsigned long long)sh->sector, i);
2197 					set_bit(STRIPE_DELAYED, &sh->state);
2198 					set_bit(STRIPE_HANDLE, &sh->state);
2199 				}
2200 			}
2201 		}
2202 	/* now if nothing is locked, and if we have enough data, we can start a
2203 	 * write request
2204 	 */
2205 	if (s->locked == 0 && rcw == 0 &&
2206 	    !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
2207 		if (must_compute > 0) {
2208 			/* We have failed blocks and need to compute them */
2209 			switch (s->failed) {
2210 			case 0:
2211 				BUG();
2212 			case 1:
2213 				compute_block_1(sh, r6s->failed_num[0], 0);
2214 				break;
2215 			case 2:
2216 				compute_block_2(sh, r6s->failed_num[0],
2217 						r6s->failed_num[1]);
2218 				break;
2219 			default: /* This request should have been failed? */
2220 				BUG();
2221 			}
2222 		}
2223 
2224 		pr_debug("Computing parity for stripe %llu\n",
2225 			(unsigned long long)sh->sector);
2226 		compute_parity6(sh, RECONSTRUCT_WRITE);
2227 		/* now every locked buffer is ready to be written */
2228 		for (i = disks; i--; )
2229 			if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
2230 				pr_debug("Writing stripe %llu block %d\n",
2231 				       (unsigned long long)sh->sector, i);
2232 				s->locked++;
2233 				set_bit(R5_Wantwrite, &sh->dev[i].flags);
2234 			}
2235 		if (s->locked == disks)
2236 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2237 				atomic_inc(&conf->pending_full_writes);
2238 		/* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
2239 		set_bit(STRIPE_INSYNC, &sh->state);
2240 
2241 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2242 			atomic_dec(&conf->preread_active_stripes);
2243 			if (atomic_read(&conf->preread_active_stripes) <
2244 			    IO_THRESHOLD)
2245 				md_wakeup_thread(conf->mddev->thread);
2246 		}
2247 	}
2248 }
2249 
2250 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
2251 				struct stripe_head_state *s, int disks)
2252 {
2253 	struct r5dev *dev = NULL;
2254 
2255 	set_bit(STRIPE_HANDLE, &sh->state);
2256 
2257 	switch (sh->check_state) {
2258 	case check_state_idle:
2259 		/* start a new check operation if there are no failures */
2260 		if (s->failed == 0) {
2261 			BUG_ON(s->uptodate != disks);
2262 			sh->check_state = check_state_run;
2263 			set_bit(STRIPE_OP_CHECK, &s->ops_request);
2264 			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2265 			s->uptodate--;
2266 			break;
2267 		}
2268 		dev = &sh->dev[s->failed_num];
2269 		/* fall through */
2270 	case check_state_compute_result:
2271 		sh->check_state = check_state_idle;
2272 		if (!dev)
2273 			dev = &sh->dev[sh->pd_idx];
2274 
2275 		/* check that a write has not made the stripe insync */
2276 		if (test_bit(STRIPE_INSYNC, &sh->state))
2277 			break;
2278 
2279 		/* either failed parity check, or recovery is happening */
2280 		BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2281 		BUG_ON(s->uptodate != disks);
2282 
2283 		set_bit(R5_LOCKED, &dev->flags);
2284 		s->locked++;
2285 		set_bit(R5_Wantwrite, &dev->flags);
2286 
2287 		clear_bit(STRIPE_DEGRADED, &sh->state);
2288 		set_bit(STRIPE_INSYNC, &sh->state);
2289 		break;
2290 	case check_state_run:
2291 		break; /* we will be called again upon completion */
2292 	case check_state_check_result:
2293 		sh->check_state = check_state_idle;
2294 
2295 		/* if a failure occurred during the check operation, leave
2296 		 * STRIPE_INSYNC not set and let the stripe be handled again
2297 		 */
2298 		if (s->failed)
2299 			break;
2300 
2301 		/* handle a successful check operation, if parity is correct
2302 		 * we are done.  Otherwise update the mismatch count and repair
2303 		 * parity if !MD_RECOVERY_CHECK
2304 		 */
2305 		if (sh->ops.zero_sum_result == 0)
2306 			/* parity is correct (on disc,
2307 			 * not in buffer any more)
2308 			 */
2309 			set_bit(STRIPE_INSYNC, &sh->state);
2310 		else {
2311 			conf->mddev->resync_mismatches += STRIPE_SECTORS;
2312 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2313 				/* don't try to repair!! */
2314 				set_bit(STRIPE_INSYNC, &sh->state);
2315 			else {
2316 				sh->check_state = check_state_compute_run;
2317 				set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2318 				set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2319 				set_bit(R5_Wantcompute,
2320 					&sh->dev[sh->pd_idx].flags);
2321 				sh->ops.target = sh->pd_idx;
2322 				s->uptodate++;
2323 			}
2324 		}
2325 		break;
2326 	case check_state_compute_run:
2327 		break;
2328 	default:
2329 		printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
2330 		       __func__, sh->check_state,
2331 		       (unsigned long long) sh->sector);
2332 		BUG();
2333 	}
2334 }
2335 
2336 
2337 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
2338 				struct stripe_head_state *s,
2339 				struct r6_state *r6s, struct page *tmp_page,
2340 				int disks)
2341 {
2342 	int update_p = 0, update_q = 0;
2343 	struct r5dev *dev;
2344 	int pd_idx = sh->pd_idx;
2345 	int qd_idx = r6s->qd_idx;
2346 
2347 	set_bit(STRIPE_HANDLE, &sh->state);
2348 
2349 	BUG_ON(s->failed > 2);
2350 	BUG_ON(s->uptodate < disks);
2351 	/* Want to check and possibly repair P and Q.
2352 	 * However there could be one 'failed' device, in which
2353 	 * case we can only check one of them, possibly using the
2354 	 * other to generate missing data
2355 	 */
2356 
2357 	/* If !tmp_page, we cannot do the calculations,
2358 	 * but as we have set STRIPE_HANDLE, we will soon be called
2359 	 * by stripe_handle with a tmp_page - just wait until then.
2360 	 */
2361 	if (tmp_page) {
2362 		if (s->failed == r6s->q_failed) {
2363 			/* The only possible failed device holds 'Q', so it
2364 			 * makes sense to check P (If anything else were failed,
2365 			 * we would have used P to recreate it).
2366 			 */
2367 			compute_block_1(sh, pd_idx, 1);
2368 			if (!page_is_zero(sh->dev[pd_idx].page)) {
2369 				compute_block_1(sh, pd_idx, 0);
2370 				update_p = 1;
2371 			}
2372 		}
2373 		if (!r6s->q_failed && s->failed < 2) {
2374 			/* q is not failed, and we didn't use it to generate
2375 			 * anything, so it makes sense to check it
2376 			 */
2377 			memcpy(page_address(tmp_page),
2378 			       page_address(sh->dev[qd_idx].page),
2379 			       STRIPE_SIZE);
2380 			compute_parity6(sh, UPDATE_PARITY);
2381 			if (memcmp(page_address(tmp_page),
2382 				   page_address(sh->dev[qd_idx].page),
2383 				   STRIPE_SIZE) != 0) {
2384 				clear_bit(STRIPE_INSYNC, &sh->state);
2385 				update_q = 1;
2386 			}
2387 		}
2388 		if (update_p || update_q) {
2389 			conf->mddev->resync_mismatches += STRIPE_SECTORS;
2390 			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2391 				/* don't try to repair!! */
2392 				update_p = update_q = 0;
2393 		}
2394 
2395 		/* now write out any block on a failed drive,
2396 		 * or P or Q if they need it
2397 		 */
2398 
2399 		if (s->failed == 2) {
2400 			dev = &sh->dev[r6s->failed_num[1]];
2401 			s->locked++;
2402 			set_bit(R5_LOCKED, &dev->flags);
2403 			set_bit(R5_Wantwrite, &dev->flags);
2404 		}
2405 		if (s->failed >= 1) {
2406 			dev = &sh->dev[r6s->failed_num[0]];
2407 			s->locked++;
2408 			set_bit(R5_LOCKED, &dev->flags);
2409 			set_bit(R5_Wantwrite, &dev->flags);
2410 		}
2411 
2412 		if (update_p) {
2413 			dev = &sh->dev[pd_idx];
2414 			s->locked++;
2415 			set_bit(R5_LOCKED, &dev->flags);
2416 			set_bit(R5_Wantwrite, &dev->flags);
2417 		}
2418 		if (update_q) {
2419 			dev = &sh->dev[qd_idx];
2420 			s->locked++;
2421 			set_bit(R5_LOCKED, &dev->flags);
2422 			set_bit(R5_Wantwrite, &dev->flags);
2423 		}
2424 		clear_bit(STRIPE_DEGRADED, &sh->state);
2425 
2426 		set_bit(STRIPE_INSYNC, &sh->state);
2427 	}
2428 }
2429 
2430 static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
2431 				struct r6_state *r6s)
2432 {
2433 	int i;
2434 
2435 	/* We have read all the blocks in this stripe and now we need to
2436 	 * copy some of them into a target stripe for expand.
2437 	 */
2438 	struct dma_async_tx_descriptor *tx = NULL;
2439 	clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2440 	for (i = 0; i < sh->disks; i++)
2441 		if (i != sh->pd_idx && (!r6s || i != r6s->qd_idx)) {
2442 			int dd_idx, pd_idx, j;
2443 			struct stripe_head *sh2;
2444 
2445 			sector_t bn = compute_blocknr(sh, i);
2446 			sector_t s = raid5_compute_sector(bn, conf->raid_disks,
2447 						conf->raid_disks -
2448 						conf->max_degraded, &dd_idx,
2449 						&pd_idx, conf);
2450 			sh2 = get_active_stripe(conf, s, conf->raid_disks,
2451 						pd_idx, 1);
2452 			if (sh2 == NULL)
2453 				/* so far only the early blocks of this stripe
2454 				 * have been requested.  When later blocks
2455 				 * get requested, we will try again
2456 				 */
2457 				continue;
2458 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
2459 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
2460 				/* must have already done this block */
2461 				release_stripe(sh2);
2462 				continue;
2463 			}
2464 
2465 			/* place all the copies on one channel */
2466 			tx = async_memcpy(sh2->dev[dd_idx].page,
2467 				sh->dev[i].page, 0, 0, STRIPE_SIZE,
2468 				ASYNC_TX_DEP_ACK, tx, NULL, NULL);
2469 
2470 			set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
2471 			set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
2472 			for (j = 0; j < conf->raid_disks; j++)
2473 				if (j != sh2->pd_idx &&
2474 				    (!r6s || j != raid6_next_disk(sh2->pd_idx,
2475 								 sh2->disks)) &&
2476 				    !test_bit(R5_Expanded, &sh2->dev[j].flags))
2477 					break;
2478 			if (j == conf->raid_disks) {
2479 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
2480 				set_bit(STRIPE_HANDLE, &sh2->state);
2481 			}
2482 			release_stripe(sh2);
2483 
2484 		}
2485 	/* done submitting copies, wait for them to complete */
2486 	if (tx) {
2487 		async_tx_ack(tx);
2488 		dma_wait_for_async_tx(tx);
2489 	}
2490 }
2491 
2492 
2493 /*
2494  * handle_stripe - do things to a stripe.
2495  *
2496  * We lock the stripe and then examine the state of various bits
2497  * to see what needs to be done.
2498  * Possible results:
2499  *    return some read request which now have data
2500  *    return some write requests which are safely on disc
2501  *    schedule a read on some buffers
2502  *    schedule a write of some buffers
2503  *    return confirmation of parity correctness
2504  *
2505  * buffers are taken off read_list or write_list, and bh_cache buffers
2506  * get BH_Lock set before the stripe lock is released.
2507  *
2508  */
2509 
2510 static void handle_stripe5(struct stripe_head *sh)
2511 {
2512 	raid5_conf_t *conf = sh->raid_conf;
2513 	int disks = sh->disks, i;
2514 	struct bio *return_bi = NULL;
2515 	struct stripe_head_state s;
2516 	struct r5dev *dev;
2517 	mdk_rdev_t *blocked_rdev = NULL;
2518 	int prexor;
2519 
2520 	memset(&s, 0, sizeof(s));
2521 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d check:%d "
2522 		 "reconstruct:%d\n", (unsigned long long)sh->sector, sh->state,
2523 		 atomic_read(&sh->count), sh->pd_idx, sh->check_state,
2524 		 sh->reconstruct_state);
2525 
2526 	spin_lock(&sh->lock);
2527 	clear_bit(STRIPE_HANDLE, &sh->state);
2528 	clear_bit(STRIPE_DELAYED, &sh->state);
2529 
2530 	s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2531 	s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2532 	s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2533 
2534 	/* Now to look around and see what can be done */
2535 	rcu_read_lock();
2536 	for (i=disks; i--; ) {
2537 		mdk_rdev_t *rdev;
2538 		struct r5dev *dev = &sh->dev[i];
2539 		clear_bit(R5_Insync, &dev->flags);
2540 
2541 		pr_debug("check %d: state 0x%lx toread %p read %p write %p "
2542 			"written %p\n",	i, dev->flags, dev->toread, dev->read,
2543 			dev->towrite, dev->written);
2544 
2545 		/* maybe we can request a biofill operation
2546 		 *
2547 		 * new wantfill requests are only permitted while
2548 		 * ops_complete_biofill is guaranteed to be inactive
2549 		 */
2550 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
2551 		    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
2552 			set_bit(R5_Wantfill, &dev->flags);
2553 
2554 		/* now count some things */
2555 		if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2556 		if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2557 		if (test_bit(R5_Wantcompute, &dev->flags)) s.compute++;
2558 
2559 		if (test_bit(R5_Wantfill, &dev->flags))
2560 			s.to_fill++;
2561 		else if (dev->toread)
2562 			s.to_read++;
2563 		if (dev->towrite) {
2564 			s.to_write++;
2565 			if (!test_bit(R5_OVERWRITE, &dev->flags))
2566 				s.non_overwrite++;
2567 		}
2568 		if (dev->written)
2569 			s.written++;
2570 		rdev = rcu_dereference(conf->disks[i].rdev);
2571 		if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
2572 			blocked_rdev = rdev;
2573 			atomic_inc(&rdev->nr_pending);
2574 			break;
2575 		}
2576 		if (!rdev || !test_bit(In_sync, &rdev->flags)) {
2577 			/* The ReadError flag will just be confusing now */
2578 			clear_bit(R5_ReadError, &dev->flags);
2579 			clear_bit(R5_ReWrite, &dev->flags);
2580 		}
2581 		if (!rdev || !test_bit(In_sync, &rdev->flags)
2582 		    || test_bit(R5_ReadError, &dev->flags)) {
2583 			s.failed++;
2584 			s.failed_num = i;
2585 		} else
2586 			set_bit(R5_Insync, &dev->flags);
2587 	}
2588 	rcu_read_unlock();
2589 
2590 	if (unlikely(blocked_rdev)) {
2591 		set_bit(STRIPE_HANDLE, &sh->state);
2592 		goto unlock;
2593 	}
2594 
2595 	if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
2596 		set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
2597 		set_bit(STRIPE_BIOFILL_RUN, &sh->state);
2598 	}
2599 
2600 	pr_debug("locked=%d uptodate=%d to_read=%d"
2601 		" to_write=%d failed=%d failed_num=%d\n",
2602 		s.locked, s.uptodate, s.to_read, s.to_write,
2603 		s.failed, s.failed_num);
2604 	/* check if the array has lost two devices and, if so, some requests might
2605 	 * need to be failed
2606 	 */
2607 	if (s.failed > 1 && s.to_read+s.to_write+s.written)
2608 		handle_failed_stripe(conf, sh, &s, disks, &return_bi);
2609 	if (s.failed > 1 && s.syncing) {
2610 		md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2611 		clear_bit(STRIPE_SYNCING, &sh->state);
2612 		s.syncing = 0;
2613 	}
2614 
2615 	/* might be able to return some write requests if the parity block
2616 	 * is safe, or on a failed drive
2617 	 */
2618 	dev = &sh->dev[sh->pd_idx];
2619 	if ( s.written &&
2620 	     ((test_bit(R5_Insync, &dev->flags) &&
2621 	       !test_bit(R5_LOCKED, &dev->flags) &&
2622 	       test_bit(R5_UPTODATE, &dev->flags)) ||
2623 	       (s.failed == 1 && s.failed_num == sh->pd_idx)))
2624 		handle_stripe_clean_event(conf, sh, disks, &return_bi);
2625 
2626 	/* Now we might consider reading some blocks, either to check/generate
2627 	 * parity, or to satisfy requests
2628 	 * or to load a block that is being partially written.
2629 	 */
2630 	if (s.to_read || s.non_overwrite ||
2631 	    (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)
2632 		handle_stripe_fill5(sh, &s, disks);
2633 
2634 	/* Now we check to see if any write operations have recently
2635 	 * completed
2636 	 */
2637 	prexor = 0;
2638 	if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
2639 		prexor = 1;
2640 	if (sh->reconstruct_state == reconstruct_state_drain_result ||
2641 	    sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
2642 		sh->reconstruct_state = reconstruct_state_idle;
2643 
2644 		/* All the 'written' buffers and the parity block are ready to
2645 		 * be written back to disk
2646 		 */
2647 		BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
2648 		for (i = disks; i--; ) {
2649 			dev = &sh->dev[i];
2650 			if (test_bit(R5_LOCKED, &dev->flags) &&
2651 				(i == sh->pd_idx || dev->written)) {
2652 				pr_debug("Writing block %d\n", i);
2653 				set_bit(R5_Wantwrite, &dev->flags);
2654 				if (prexor)
2655 					continue;
2656 				if (!test_bit(R5_Insync, &dev->flags) ||
2657 				    (i == sh->pd_idx && s.failed == 0))
2658 					set_bit(STRIPE_INSYNC, &sh->state);
2659 			}
2660 		}
2661 		if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2662 			atomic_dec(&conf->preread_active_stripes);
2663 			if (atomic_read(&conf->preread_active_stripes) <
2664 				IO_THRESHOLD)
2665 				md_wakeup_thread(conf->mddev->thread);
2666 		}
2667 	}
2668 
2669 	/* Now to consider new write requests and what else, if anything
2670 	 * should be read.  We do not handle new writes when:
2671 	 * 1/ A 'write' operation (copy+xor) is already in flight.
2672 	 * 2/ A 'check' operation is in flight, as it may clobber the parity
2673 	 *    block.
2674 	 */
2675 	if (s.to_write && !sh->reconstruct_state && !sh->check_state)
2676 		handle_stripe_dirtying5(conf, sh, &s, disks);
2677 
2678 	/* maybe we need to check and possibly fix the parity for this stripe
2679 	 * Any reads will already have been scheduled, so we just see if enough
2680 	 * data is available.  The parity check is held off while parity
2681 	 * dependent operations are in flight.
2682 	 */
2683 	if (sh->check_state ||
2684 	    (s.syncing && s.locked == 0 &&
2685 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
2686 	     !test_bit(STRIPE_INSYNC, &sh->state)))
2687 		handle_parity_checks5(conf, sh, &s, disks);
2688 
2689 	if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2690 		md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2691 		clear_bit(STRIPE_SYNCING, &sh->state);
2692 	}
2693 
2694 	/* If the failed drive is just a ReadError, then we might need to progress
2695 	 * the repair/check process
2696 	 */
2697 	if (s.failed == 1 && !conf->mddev->ro &&
2698 	    test_bit(R5_ReadError, &sh->dev[s.failed_num].flags)
2699 	    && !test_bit(R5_LOCKED, &sh->dev[s.failed_num].flags)
2700 	    && test_bit(R5_UPTODATE, &sh->dev[s.failed_num].flags)
2701 		) {
2702 		dev = &sh->dev[s.failed_num];
2703 		if (!test_bit(R5_ReWrite, &dev->flags)) {
2704 			set_bit(R5_Wantwrite, &dev->flags);
2705 			set_bit(R5_ReWrite, &dev->flags);
2706 			set_bit(R5_LOCKED, &dev->flags);
2707 			s.locked++;
2708 		} else {
2709 			/* let's read it back */
2710 			set_bit(R5_Wantread, &dev->flags);
2711 			set_bit(R5_LOCKED, &dev->flags);
2712 			s.locked++;
2713 		}
2714 	}
2715 
2716 	/* Finish reconstruct operations initiated by the expansion process */
2717 	if (sh->reconstruct_state == reconstruct_state_result) {
2718 		sh->reconstruct_state = reconstruct_state_idle;
2719 		clear_bit(STRIPE_EXPANDING, &sh->state);
2720 		for (i = conf->raid_disks; i--; )
2721 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
2722 			set_bit(R5_LOCKED, &dev->flags);
2723 			s.locked++;
2724 	}
2725 
2726 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
2727 	    !sh->reconstruct_state) {
2728 		/* Need to write out all blocks after computing parity */
2729 		sh->disks = conf->raid_disks;
2730 		sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
2731 			conf->raid_disks);
2732 		schedule_reconstruction5(sh, &s, 1, 1);
2733 	} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
2734 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
2735 		atomic_dec(&conf->reshape_stripes);
2736 		wake_up(&conf->wait_for_overlap);
2737 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
2738 	}
2739 
2740 	if (s.expanding && s.locked == 0 &&
2741 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
2742 		handle_stripe_expansion(conf, sh, NULL);
2743 
2744  unlock:
2745 	spin_unlock(&sh->lock);
2746 
2747 	/* wait for this device to become unblocked */
2748 	if (unlikely(blocked_rdev))
2749 		md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
2750 
2751 	if (s.ops_request)
2752 		raid5_run_ops(sh, s.ops_request);
2753 
2754 	ops_run_io(sh, &s);
2755 
2756 	return_io(return_bi);
2757 }
2758 
2759 static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
2760 {
2761 	raid6_conf_t *conf = sh->raid_conf;
2762 	int disks = sh->disks;
2763 	struct bio *return_bi = NULL;
2764 	int i, pd_idx = sh->pd_idx;
2765 	struct stripe_head_state s;
2766 	struct r6_state r6s;
2767 	struct r5dev *dev, *pdev, *qdev;
2768 	mdk_rdev_t *blocked_rdev = NULL;
2769 
2770 	r6s.qd_idx = raid6_next_disk(pd_idx, disks);
2771 	pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
2772 		"pd_idx=%d, qd_idx=%d\n",
2773 	       (unsigned long long)sh->sector, sh->state,
2774 	       atomic_read(&sh->count), pd_idx, r6s.qd_idx);
2775 	memset(&s, 0, sizeof(s));
2776 
2777 	spin_lock(&sh->lock);
2778 	clear_bit(STRIPE_HANDLE, &sh->state);
2779 	clear_bit(STRIPE_DELAYED, &sh->state);
2780 
2781 	s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2782 	s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2783 	s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2784 	/* Now to look around and see what can be done */
2785 
2786 	rcu_read_lock();
2787 	for (i=disks; i--; ) {
2788 		mdk_rdev_t *rdev;
2789 		dev = &sh->dev[i];
2790 		clear_bit(R5_Insync, &dev->flags);
2791 
2792 		pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
2793 			i, dev->flags, dev->toread, dev->towrite, dev->written);
2794 		/* maybe we can reply to a read */
2795 		if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
2796 			struct bio *rbi, *rbi2;
2797 			pr_debug("Return read for disc %d\n", i);
2798 			spin_lock_irq(&conf->device_lock);
2799 			rbi = dev->toread;
2800 			dev->toread = NULL;
2801 			if (test_and_clear_bit(R5_Overlap, &dev->flags))
2802 				wake_up(&conf->wait_for_overlap);
2803 			spin_unlock_irq(&conf->device_lock);
2804 			while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
2805 				copy_data(0, rbi, dev->page, dev->sector);
2806 				rbi2 = r5_next_bio(rbi, dev->sector);
2807 				spin_lock_irq(&conf->device_lock);
2808 				if (--rbi->bi_phys_segments == 0) {
2809 					rbi->bi_next = return_bi;
2810 					return_bi = rbi;
2811 				}
2812 				spin_unlock_irq(&conf->device_lock);
2813 				rbi = rbi2;
2814 			}
2815 		}
2816 
2817 		/* now count some things */
2818 		if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2819 		if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2820 
2821 
2822 		if (dev->toread)
2823 			s.to_read++;
2824 		if (dev->towrite) {
2825 			s.to_write++;
2826 			if (!test_bit(R5_OVERWRITE, &dev->flags))
2827 				s.non_overwrite++;
2828 		}
2829 		if (dev->written)
2830 			s.written++;
2831 		rdev = rcu_dereference(conf->disks[i].rdev);
2832 		if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
2833 			blocked_rdev = rdev;
2834 			atomic_inc(&rdev->nr_pending);
2835 			break;
2836 		}
2837 		if (!rdev || !test_bit(In_sync, &rdev->flags)) {
2838 			/* The ReadError flag will just be confusing now */
2839 			clear_bit(R5_ReadError, &dev->flags);
2840 			clear_bit(R5_ReWrite, &dev->flags);
2841 		}
2842 		if (!rdev || !test_bit(In_sync, &rdev->flags)
2843 		    || test_bit(R5_ReadError, &dev->flags)) {
2844 			if (s.failed < 2)
2845 				r6s.failed_num[s.failed] = i;
2846 			s.failed++;
2847 		} else
2848 			set_bit(R5_Insync, &dev->flags);
2849 	}
2850 	rcu_read_unlock();
2851 
2852 	if (unlikely(blocked_rdev)) {
2853 		set_bit(STRIPE_HANDLE, &sh->state);
2854 		goto unlock;
2855 	}
2856 	pr_debug("locked=%d uptodate=%d to_read=%d"
2857 	       " to_write=%d failed=%d failed_num=%d,%d\n",
2858 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
2859 	       r6s.failed_num[0], r6s.failed_num[1]);
2860 	/* check if the array has lost >2 devices and, if so, some requests
2861 	 * might need to be failed
2862 	 */
2863 	if (s.failed > 2 && s.to_read+s.to_write+s.written)
2864 		handle_failed_stripe(conf, sh, &s, disks, &return_bi);
2865 	if (s.failed > 2 && s.syncing) {
2866 		md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2867 		clear_bit(STRIPE_SYNCING, &sh->state);
2868 		s.syncing = 0;
2869 	}
2870 
2871 	/*
2872 	 * might be able to return some write requests if the parity blocks
2873 	 * are safe, or on a failed drive
2874 	 */
2875 	pdev = &sh->dev[pd_idx];
2876 	r6s.p_failed = (s.failed >= 1 && r6s.failed_num[0] == pd_idx)
2877 		|| (s.failed >= 2 && r6s.failed_num[1] == pd_idx);
2878 	qdev = &sh->dev[r6s.qd_idx];
2879 	r6s.q_failed = (s.failed >= 1 && r6s.failed_num[0] == r6s.qd_idx)
2880 		|| (s.failed >= 2 && r6s.failed_num[1] == r6s.qd_idx);
2881 
2882 	if ( s.written &&
2883 	     ( r6s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
2884 			     && !test_bit(R5_LOCKED, &pdev->flags)
2885 			     && test_bit(R5_UPTODATE, &pdev->flags)))) &&
2886 	     ( r6s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
2887 			     && !test_bit(R5_LOCKED, &qdev->flags)
2888 			     && test_bit(R5_UPTODATE, &qdev->flags)))))
2889 		handle_stripe_clean_event(conf, sh, disks, &return_bi);
2890 
2891 	/* Now we might consider reading some blocks, either to check/generate
2892 	 * parity, or to satisfy requests
2893 	 * or to load a block that is being partially written.
2894 	 */
2895 	if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
2896 	    (s.syncing && (s.uptodate < disks)) || s.expanding)
2897 		handle_stripe_fill6(sh, &s, &r6s, disks);
2898 
2899 	/* now to consider writing and what else, if anything should be read */
2900 	if (s.to_write)
2901 		handle_stripe_dirtying6(conf, sh, &s, &r6s, disks);
2902 
2903 	/* maybe we need to check and possibly fix the parity for this stripe
2904 	 * Any reads will already have been scheduled, so we just see if enough
2905 	 * data is available
2906 	 */
2907 	if (s.syncing && s.locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state))
2908 		handle_parity_checks6(conf, sh, &s, &r6s, tmp_page, disks);
2909 
2910 	if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2911 		md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2912 		clear_bit(STRIPE_SYNCING, &sh->state);
2913 	}
2914 
2915 	/* If the failed drives are just a ReadError, then we might need
2916 	 * to progress the repair/check process
2917 	 */
2918 	if (s.failed <= 2 && !conf->mddev->ro)
2919 		for (i = 0; i < s.failed; i++) {
2920 			dev = &sh->dev[r6s.failed_num[i]];
2921 			if (test_bit(R5_ReadError, &dev->flags)
2922 			    && !test_bit(R5_LOCKED, &dev->flags)
2923 			    && test_bit(R5_UPTODATE, &dev->flags)
2924 				) {
2925 				if (!test_bit(R5_ReWrite, &dev->flags)) {
2926 					set_bit(R5_Wantwrite, &dev->flags);
2927 					set_bit(R5_ReWrite, &dev->flags);
2928 					set_bit(R5_LOCKED, &dev->flags);
2929 				} else {
2930 					/* let's read it back */
2931 					set_bit(R5_Wantread, &dev->flags);
2932 					set_bit(R5_LOCKED, &dev->flags);
2933 				}
2934 			}
2935 		}
2936 
2937 	if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
2938 		/* Need to write out all blocks after computing P&Q */
2939 		sh->disks = conf->raid_disks;
2940 		sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
2941 					     conf->raid_disks);
2942 		compute_parity6(sh, RECONSTRUCT_WRITE);
2943 		for (i = conf->raid_disks ; i-- ;  ) {
2944 			set_bit(R5_LOCKED, &sh->dev[i].flags);
2945 			s.locked++;
2946 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
2947 		}
2948 		clear_bit(STRIPE_EXPANDING, &sh->state);
2949 	} else if (s.expanded) {
2950 		clear_bit(STRIPE_EXPAND_READY, &sh->state);
2951 		atomic_dec(&conf->reshape_stripes);
2952 		wake_up(&conf->wait_for_overlap);
2953 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
2954 	}
2955 
2956 	if (s.expanding && s.locked == 0 &&
2957 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
2958 		handle_stripe_expansion(conf, sh, &r6s);
2959 
2960  unlock:
2961 	spin_unlock(&sh->lock);
2962 
2963 	/* wait for this device to become unblocked */
2964 	if (unlikely(blocked_rdev))
2965 		md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
2966 
2967 	ops_run_io(sh, &s);
2968 
2969 	return_io(return_bi);
2970 }
2971 
2972 static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
2973 {
2974 	if (sh->raid_conf->level == 6)
2975 		handle_stripe6(sh, tmp_page);
2976 	else
2977 		handle_stripe5(sh);
2978 }
2979 
2980 
2981 
2982 static void raid5_activate_delayed(raid5_conf_t *conf)
2983 {
2984 	if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
2985 		while (!list_empty(&conf->delayed_list)) {
2986 			struct list_head *l = conf->delayed_list.next;
2987 			struct stripe_head *sh;
2988 			sh = list_entry(l, struct stripe_head, lru);
2989 			list_del_init(l);
2990 			clear_bit(STRIPE_DELAYED, &sh->state);
2991 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
2992 				atomic_inc(&conf->preread_active_stripes);
2993 			list_add_tail(&sh->lru, &conf->hold_list);
2994 		}
2995 	} else
2996 		blk_plug_device(conf->mddev->queue);
2997 }
2998 
2999 static void activate_bit_delay(raid5_conf_t *conf)
3000 {
3001 	/* device_lock is held */
3002 	struct list_head head;
3003 	list_add(&head, &conf->bitmap_list);
3004 	list_del_init(&conf->bitmap_list);
3005 	while (!list_empty(&head)) {
3006 		struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3007 		list_del_init(&sh->lru);
3008 		atomic_inc(&sh->count);
3009 		__release_stripe(conf, sh);
3010 	}
3011 }
3012 
3013 static void unplug_slaves(mddev_t *mddev)
3014 {
3015 	raid5_conf_t *conf = mddev_to_conf(mddev);
3016 	int i;
3017 
3018 	rcu_read_lock();
3019 	for (i=0; i<mddev->raid_disks; i++) {
3020 		mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
3021 		if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
3022 			struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
3023 
3024 			atomic_inc(&rdev->nr_pending);
3025 			rcu_read_unlock();
3026 
3027 			blk_unplug(r_queue);
3028 
3029 			rdev_dec_pending(rdev, mddev);
3030 			rcu_read_lock();
3031 		}
3032 	}
3033 	rcu_read_unlock();
3034 }
3035 
3036 static void raid5_unplug_device(struct request_queue *q)
3037 {
3038 	mddev_t *mddev = q->queuedata;
3039 	raid5_conf_t *conf = mddev_to_conf(mddev);
3040 	unsigned long flags;
3041 
3042 	spin_lock_irqsave(&conf->device_lock, flags);
3043 
3044 	if (blk_remove_plug(q)) {
3045 		conf->seq_flush++;
3046 		raid5_activate_delayed(conf);
3047 	}
3048 	md_wakeup_thread(mddev->thread);
3049 
3050 	spin_unlock_irqrestore(&conf->device_lock, flags);
3051 
3052 	unplug_slaves(mddev);
3053 }
3054 
3055 static int raid5_congested(void *data, int bits)
3056 {
3057 	mddev_t *mddev = data;
3058 	raid5_conf_t *conf = mddev_to_conf(mddev);
3059 
3060 	/* No difference between reads and writes.  Just check
3061 	 * how busy the stripe_cache is
3062 	 */
3063 	if (conf->inactive_blocked)
3064 		return 1;
3065 	if (conf->quiesce)
3066 		return 1;
3067 	if (list_empty_careful(&conf->inactive_list))
3068 		return 1;
3069 
3070 	return 0;
3071 }
3072 
3073 /* We want read requests to align with chunks where possible,
3074  * but write requests don't need to.
3075  */
3076 static int raid5_mergeable_bvec(struct request_queue *q,
3077 				struct bvec_merge_data *bvm,
3078 				struct bio_vec *biovec)
3079 {
3080 	mddev_t *mddev = q->queuedata;
3081 	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3082 	int max;
3083 	unsigned int chunk_sectors = mddev->chunk_size >> 9;
3084 	unsigned int bio_sectors = bvm->bi_size >> 9;
3085 
3086 	if ((bvm->bi_rw & 1) == WRITE)
3087 		return biovec->bv_len; /* always allow writes to be mergeable */
3088 
3089 	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3090 	if (max < 0) max = 0;
3091 	if (max <= biovec->bv_len && bio_sectors == 0)
3092 		return biovec->bv_len;
3093 	else
3094 		return max;
3095 }
3096 
3097 
3098 static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
3099 {
3100 	sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3101 	unsigned int chunk_sectors = mddev->chunk_size >> 9;
3102 	unsigned int bio_sectors = bio->bi_size >> 9;
3103 
3104 	return  chunk_sectors >=
3105 		((sector & (chunk_sectors - 1)) + bio_sectors);
3106 }
3107 
3108 /*
3109  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3110  *  later sampled by raid5d.
3111  */
3112 static void add_bio_to_retry(struct bio *bi,raid5_conf_t *conf)
3113 {
3114 	unsigned long flags;
3115 
3116 	spin_lock_irqsave(&conf->device_lock, flags);
3117 
3118 	bi->bi_next = conf->retry_read_aligned_list;
3119 	conf->retry_read_aligned_list = bi;
3120 
3121 	spin_unlock_irqrestore(&conf->device_lock, flags);
3122 	md_wakeup_thread(conf->mddev->thread);
3123 }
3124 
3125 
3126 static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
3127 {
3128 	struct bio *bi;
3129 
3130 	bi = conf->retry_read_aligned;
3131 	if (bi) {
3132 		conf->retry_read_aligned = NULL;
3133 		return bi;
3134 	}
3135 	bi = conf->retry_read_aligned_list;
3136 	if(bi) {
3137 		conf->retry_read_aligned_list = bi->bi_next;
3138 		bi->bi_next = NULL;
3139 		bi->bi_phys_segments = 1; /* biased count of active stripes */
3140 		bi->bi_hw_segments = 0; /* count of processed stripes */
3141 	}
3142 
3143 	return bi;
3144 }
3145 
3146 
3147 /*
3148  *  The "raid5_align_endio" should check if the read succeeded and if it
3149  *  did, call bio_endio on the original bio (having bio_put the new bio
3150  *  first).
3151  *  If the read failed..
3152  */
3153 static void raid5_align_endio(struct bio *bi, int error)
3154 {
3155 	struct bio* raid_bi  = bi->bi_private;
3156 	mddev_t *mddev;
3157 	raid5_conf_t *conf;
3158 	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3159 	mdk_rdev_t *rdev;
3160 
3161 	bio_put(bi);
3162 
3163 	mddev = raid_bi->bi_bdev->bd_disk->queue->queuedata;
3164 	conf = mddev_to_conf(mddev);
3165 	rdev = (void*)raid_bi->bi_next;
3166 	raid_bi->bi_next = NULL;
3167 
3168 	rdev_dec_pending(rdev, conf->mddev);
3169 
3170 	if (!error && uptodate) {
3171 		bio_endio(raid_bi, 0);
3172 		if (atomic_dec_and_test(&conf->active_aligned_reads))
3173 			wake_up(&conf->wait_for_stripe);
3174 		return;
3175 	}
3176 
3177 
3178 	pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3179 
3180 	add_bio_to_retry(raid_bi, conf);
3181 }
3182 
3183 static int bio_fits_rdev(struct bio *bi)
3184 {
3185 	struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3186 
3187 	if ((bi->bi_size>>9) > q->max_sectors)
3188 		return 0;
3189 	blk_recount_segments(q, bi);
3190 	if (bi->bi_phys_segments > q->max_phys_segments ||
3191 	    bi->bi_hw_segments > q->max_hw_segments)
3192 		return 0;
3193 
3194 	if (q->merge_bvec_fn)
3195 		/* it's too hard to apply the merge_bvec_fn at this stage,
3196 		 * just just give up
3197 		 */
3198 		return 0;
3199 
3200 	return 1;
3201 }
3202 
3203 
3204 static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
3205 {
3206 	mddev_t *mddev = q->queuedata;
3207 	raid5_conf_t *conf = mddev_to_conf(mddev);
3208 	const unsigned int raid_disks = conf->raid_disks;
3209 	const unsigned int data_disks = raid_disks - conf->max_degraded;
3210 	unsigned int dd_idx, pd_idx;
3211 	struct bio* align_bi;
3212 	mdk_rdev_t *rdev;
3213 
3214 	if (!in_chunk_boundary(mddev, raid_bio)) {
3215 		pr_debug("chunk_aligned_read : non aligned\n");
3216 		return 0;
3217 	}
3218 	/*
3219  	 * use bio_clone to make a copy of the bio
3220 	 */
3221 	align_bi = bio_clone(raid_bio, GFP_NOIO);
3222 	if (!align_bi)
3223 		return 0;
3224 	/*
3225 	 *   set bi_end_io to a new function, and set bi_private to the
3226 	 *     original bio.
3227 	 */
3228 	align_bi->bi_end_io  = raid5_align_endio;
3229 	align_bi->bi_private = raid_bio;
3230 	/*
3231 	 *	compute position
3232 	 */
3233 	align_bi->bi_sector =  raid5_compute_sector(raid_bio->bi_sector,
3234 					raid_disks,
3235 					data_disks,
3236 					&dd_idx,
3237 					&pd_idx,
3238 					conf);
3239 
3240 	rcu_read_lock();
3241 	rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3242 	if (rdev && test_bit(In_sync, &rdev->flags)) {
3243 		atomic_inc(&rdev->nr_pending);
3244 		rcu_read_unlock();
3245 		raid_bio->bi_next = (void*)rdev;
3246 		align_bi->bi_bdev =  rdev->bdev;
3247 		align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
3248 		align_bi->bi_sector += rdev->data_offset;
3249 
3250 		if (!bio_fits_rdev(align_bi)) {
3251 			/* too big in some way */
3252 			bio_put(align_bi);
3253 			rdev_dec_pending(rdev, mddev);
3254 			return 0;
3255 		}
3256 
3257 		spin_lock_irq(&conf->device_lock);
3258 		wait_event_lock_irq(conf->wait_for_stripe,
3259 				    conf->quiesce == 0,
3260 				    conf->device_lock, /* nothing */);
3261 		atomic_inc(&conf->active_aligned_reads);
3262 		spin_unlock_irq(&conf->device_lock);
3263 
3264 		generic_make_request(align_bi);
3265 		return 1;
3266 	} else {
3267 		rcu_read_unlock();
3268 		bio_put(align_bi);
3269 		return 0;
3270 	}
3271 }
3272 
3273 /* __get_priority_stripe - get the next stripe to process
3274  *
3275  * Full stripe writes are allowed to pass preread active stripes up until
3276  * the bypass_threshold is exceeded.  In general the bypass_count
3277  * increments when the handle_list is handled before the hold_list; however, it
3278  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
3279  * stripe with in flight i/o.  The bypass_count will be reset when the
3280  * head of the hold_list has changed, i.e. the head was promoted to the
3281  * handle_list.
3282  */
3283 static struct stripe_head *__get_priority_stripe(raid5_conf_t *conf)
3284 {
3285 	struct stripe_head *sh;
3286 
3287 	pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
3288 		  __func__,
3289 		  list_empty(&conf->handle_list) ? "empty" : "busy",
3290 		  list_empty(&conf->hold_list) ? "empty" : "busy",
3291 		  atomic_read(&conf->pending_full_writes), conf->bypass_count);
3292 
3293 	if (!list_empty(&conf->handle_list)) {
3294 		sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
3295 
3296 		if (list_empty(&conf->hold_list))
3297 			conf->bypass_count = 0;
3298 		else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
3299 			if (conf->hold_list.next == conf->last_hold)
3300 				conf->bypass_count++;
3301 			else {
3302 				conf->last_hold = conf->hold_list.next;
3303 				conf->bypass_count -= conf->bypass_threshold;
3304 				if (conf->bypass_count < 0)
3305 					conf->bypass_count = 0;
3306 			}
3307 		}
3308 	} else if (!list_empty(&conf->hold_list) &&
3309 		   ((conf->bypass_threshold &&
3310 		     conf->bypass_count > conf->bypass_threshold) ||
3311 		    atomic_read(&conf->pending_full_writes) == 0)) {
3312 		sh = list_entry(conf->hold_list.next,
3313 				typeof(*sh), lru);
3314 		conf->bypass_count -= conf->bypass_threshold;
3315 		if (conf->bypass_count < 0)
3316 			conf->bypass_count = 0;
3317 	} else
3318 		return NULL;
3319 
3320 	list_del_init(&sh->lru);
3321 	atomic_inc(&sh->count);
3322 	BUG_ON(atomic_read(&sh->count) != 1);
3323 	return sh;
3324 }
3325 
3326 static int make_request(struct request_queue *q, struct bio * bi)
3327 {
3328 	mddev_t *mddev = q->queuedata;
3329 	raid5_conf_t *conf = mddev_to_conf(mddev);
3330 	unsigned int dd_idx, pd_idx;
3331 	sector_t new_sector;
3332 	sector_t logical_sector, last_sector;
3333 	struct stripe_head *sh;
3334 	const int rw = bio_data_dir(bi);
3335 	int remaining;
3336 
3337 	if (unlikely(bio_barrier(bi))) {
3338 		bio_endio(bi, -EOPNOTSUPP);
3339 		return 0;
3340 	}
3341 
3342 	md_write_start(mddev, bi);
3343 
3344 	disk_stat_inc(mddev->gendisk, ios[rw]);
3345 	disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
3346 
3347 	if (rw == READ &&
3348 	     mddev->reshape_position == MaxSector &&
3349 	     chunk_aligned_read(q,bi))
3350             	return 0;
3351 
3352 	logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3353 	last_sector = bi->bi_sector + (bi->bi_size>>9);
3354 	bi->bi_next = NULL;
3355 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
3356 
3357 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
3358 		DEFINE_WAIT(w);
3359 		int disks, data_disks;
3360 
3361 	retry:
3362 		prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
3363 		if (likely(conf->expand_progress == MaxSector))
3364 			disks = conf->raid_disks;
3365 		else {
3366 			/* spinlock is needed as expand_progress may be
3367 			 * 64bit on a 32bit platform, and so it might be
3368 			 * possible to see a half-updated value
3369 			 * Ofcourse expand_progress could change after
3370 			 * the lock is dropped, so once we get a reference
3371 			 * to the stripe that we think it is, we will have
3372 			 * to check again.
3373 			 */
3374 			spin_lock_irq(&conf->device_lock);
3375 			disks = conf->raid_disks;
3376 			if (logical_sector >= conf->expand_progress)
3377 				disks = conf->previous_raid_disks;
3378 			else {
3379 				if (logical_sector >= conf->expand_lo) {
3380 					spin_unlock_irq(&conf->device_lock);
3381 					schedule();
3382 					goto retry;
3383 				}
3384 			}
3385 			spin_unlock_irq(&conf->device_lock);
3386 		}
3387 		data_disks = disks - conf->max_degraded;
3388 
3389  		new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
3390 						  &dd_idx, &pd_idx, conf);
3391 		pr_debug("raid5: make_request, sector %llu logical %llu\n",
3392 			(unsigned long long)new_sector,
3393 			(unsigned long long)logical_sector);
3394 
3395 		sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
3396 		if (sh) {
3397 			if (unlikely(conf->expand_progress != MaxSector)) {
3398 				/* expansion might have moved on while waiting for a
3399 				 * stripe, so we must do the range check again.
3400 				 * Expansion could still move past after this
3401 				 * test, but as we are holding a reference to
3402 				 * 'sh', we know that if that happens,
3403 				 *  STRIPE_EXPANDING will get set and the expansion
3404 				 * won't proceed until we finish with the stripe.
3405 				 */
3406 				int must_retry = 0;
3407 				spin_lock_irq(&conf->device_lock);
3408 				if (logical_sector <  conf->expand_progress &&
3409 				    disks == conf->previous_raid_disks)
3410 					/* mismatch, need to try again */
3411 					must_retry = 1;
3412 				spin_unlock_irq(&conf->device_lock);
3413 				if (must_retry) {
3414 					release_stripe(sh);
3415 					goto retry;
3416 				}
3417 			}
3418 			/* FIXME what if we get a false positive because these
3419 			 * are being updated.
3420 			 */
3421 			if (logical_sector >= mddev->suspend_lo &&
3422 			    logical_sector < mddev->suspend_hi) {
3423 				release_stripe(sh);
3424 				schedule();
3425 				goto retry;
3426 			}
3427 
3428 			if (test_bit(STRIPE_EXPANDING, &sh->state) ||
3429 			    !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
3430 				/* Stripe is busy expanding or
3431 				 * add failed due to overlap.  Flush everything
3432 				 * and wait a while
3433 				 */
3434 				raid5_unplug_device(mddev->queue);
3435 				release_stripe(sh);
3436 				schedule();
3437 				goto retry;
3438 			}
3439 			finish_wait(&conf->wait_for_overlap, &w);
3440 			set_bit(STRIPE_HANDLE, &sh->state);
3441 			clear_bit(STRIPE_DELAYED, &sh->state);
3442 			release_stripe(sh);
3443 		} else {
3444 			/* cannot get stripe for read-ahead, just give-up */
3445 			clear_bit(BIO_UPTODATE, &bi->bi_flags);
3446 			finish_wait(&conf->wait_for_overlap, &w);
3447 			break;
3448 		}
3449 
3450 	}
3451 	spin_lock_irq(&conf->device_lock);
3452 	remaining = --bi->bi_phys_segments;
3453 	spin_unlock_irq(&conf->device_lock);
3454 	if (remaining == 0) {
3455 
3456 		if ( rw == WRITE )
3457 			md_write_end(mddev);
3458 
3459 		bio_endio(bi, 0);
3460 	}
3461 	return 0;
3462 }
3463 
3464 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
3465 {
3466 	/* reshaping is quite different to recovery/resync so it is
3467 	 * handled quite separately ... here.
3468 	 *
3469 	 * On each call to sync_request, we gather one chunk worth of
3470 	 * destination stripes and flag them as expanding.
3471 	 * Then we find all the source stripes and request reads.
3472 	 * As the reads complete, handle_stripe will copy the data
3473 	 * into the destination stripe and release that stripe.
3474 	 */
3475 	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3476 	struct stripe_head *sh;
3477 	int pd_idx;
3478 	sector_t first_sector, last_sector;
3479 	int raid_disks = conf->previous_raid_disks;
3480 	int data_disks = raid_disks - conf->max_degraded;
3481 	int new_data_disks = conf->raid_disks - conf->max_degraded;
3482 	int i;
3483 	int dd_idx;
3484 	sector_t writepos, safepos, gap;
3485 
3486 	if (sector_nr == 0 &&
3487 	    conf->expand_progress != 0) {
3488 		/* restarting in the middle, skip the initial sectors */
3489 		sector_nr = conf->expand_progress;
3490 		sector_div(sector_nr, new_data_disks);
3491 		*skipped = 1;
3492 		return sector_nr;
3493 	}
3494 
3495 	/* we update the metadata when there is more than 3Meg
3496 	 * in the block range (that is rather arbitrary, should
3497 	 * probably be time based) or when the data about to be
3498 	 * copied would over-write the source of the data at
3499 	 * the front of the range.
3500 	 * i.e. one new_stripe forward from expand_progress new_maps
3501 	 * to after where expand_lo old_maps to
3502 	 */
3503 	writepos = conf->expand_progress +
3504 		conf->chunk_size/512*(new_data_disks);
3505 	sector_div(writepos, new_data_disks);
3506 	safepos = conf->expand_lo;
3507 	sector_div(safepos, data_disks);
3508 	gap = conf->expand_progress - conf->expand_lo;
3509 
3510 	if (writepos >= safepos ||
3511 	    gap > (new_data_disks)*3000*2 /*3Meg*/) {
3512 		/* Cannot proceed until we've updated the superblock... */
3513 		wait_event(conf->wait_for_overlap,
3514 			   atomic_read(&conf->reshape_stripes)==0);
3515 		mddev->reshape_position = conf->expand_progress;
3516 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
3517 		md_wakeup_thread(mddev->thread);
3518 		wait_event(mddev->sb_wait, mddev->flags == 0 ||
3519 			   kthread_should_stop());
3520 		spin_lock_irq(&conf->device_lock);
3521 		conf->expand_lo = mddev->reshape_position;
3522 		spin_unlock_irq(&conf->device_lock);
3523 		wake_up(&conf->wait_for_overlap);
3524 	}
3525 
3526 	for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
3527 		int j;
3528 		int skipped = 0;
3529 		pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
3530 		sh = get_active_stripe(conf, sector_nr+i,
3531 				       conf->raid_disks, pd_idx, 0);
3532 		set_bit(STRIPE_EXPANDING, &sh->state);
3533 		atomic_inc(&conf->reshape_stripes);
3534 		/* If any of this stripe is beyond the end of the old
3535 		 * array, then we need to zero those blocks
3536 		 */
3537 		for (j=sh->disks; j--;) {
3538 			sector_t s;
3539 			if (j == sh->pd_idx)
3540 				continue;
3541 			if (conf->level == 6 &&
3542 			    j == raid6_next_disk(sh->pd_idx, sh->disks))
3543 				continue;
3544 			s = compute_blocknr(sh, j);
3545 			if (s < mddev->array_sectors) {
3546 				skipped = 1;
3547 				continue;
3548 			}
3549 			memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
3550 			set_bit(R5_Expanded, &sh->dev[j].flags);
3551 			set_bit(R5_UPTODATE, &sh->dev[j].flags);
3552 		}
3553 		if (!skipped) {
3554 			set_bit(STRIPE_EXPAND_READY, &sh->state);
3555 			set_bit(STRIPE_HANDLE, &sh->state);
3556 		}
3557 		release_stripe(sh);
3558 	}
3559 	spin_lock_irq(&conf->device_lock);
3560 	conf->expand_progress = (sector_nr + i) * new_data_disks;
3561 	spin_unlock_irq(&conf->device_lock);
3562 	/* Ok, those stripe are ready. We can start scheduling
3563 	 * reads on the source stripes.
3564 	 * The source stripes are determined by mapping the first and last
3565 	 * block on the destination stripes.
3566 	 */
3567 	first_sector =
3568 		raid5_compute_sector(sector_nr*(new_data_disks),
3569 				     raid_disks, data_disks,
3570 				     &dd_idx, &pd_idx, conf);
3571 	last_sector =
3572 		raid5_compute_sector((sector_nr+conf->chunk_size/512)
3573 				     *(new_data_disks) -1,
3574 				     raid_disks, data_disks,
3575 				     &dd_idx, &pd_idx, conf);
3576 	if (last_sector >= (mddev->size<<1))
3577 		last_sector = (mddev->size<<1)-1;
3578 	while (first_sector <= last_sector) {
3579 		pd_idx = stripe_to_pdidx(first_sector, conf,
3580 					 conf->previous_raid_disks);
3581 		sh = get_active_stripe(conf, first_sector,
3582 				       conf->previous_raid_disks, pd_idx, 0);
3583 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3584 		set_bit(STRIPE_HANDLE, &sh->state);
3585 		release_stripe(sh);
3586 		first_sector += STRIPE_SECTORS;
3587 	}
3588 	/* If this takes us to the resync_max point where we have to pause,
3589 	 * then we need to write out the superblock.
3590 	 */
3591 	sector_nr += conf->chunk_size>>9;
3592 	if (sector_nr >= mddev->resync_max) {
3593 		/* Cannot proceed until we've updated the superblock... */
3594 		wait_event(conf->wait_for_overlap,
3595 			   atomic_read(&conf->reshape_stripes) == 0);
3596 		mddev->reshape_position = conf->expand_progress;
3597 		set_bit(MD_CHANGE_DEVS, &mddev->flags);
3598 		md_wakeup_thread(mddev->thread);
3599 		wait_event(mddev->sb_wait,
3600 			   !test_bit(MD_CHANGE_DEVS, &mddev->flags)
3601 			   || kthread_should_stop());
3602 		spin_lock_irq(&conf->device_lock);
3603 		conf->expand_lo = mddev->reshape_position;
3604 		spin_unlock_irq(&conf->device_lock);
3605 		wake_up(&conf->wait_for_overlap);
3606 	}
3607 	return conf->chunk_size>>9;
3608 }
3609 
3610 /* FIXME go_faster isn't used */
3611 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
3612 {
3613 	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3614 	struct stripe_head *sh;
3615 	int pd_idx;
3616 	int raid_disks = conf->raid_disks;
3617 	sector_t max_sector = mddev->size << 1;
3618 	int sync_blocks;
3619 	int still_degraded = 0;
3620 	int i;
3621 
3622 	if (sector_nr >= max_sector) {
3623 		/* just being told to finish up .. nothing much to do */
3624 		unplug_slaves(mddev);
3625 		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
3626 			end_reshape(conf);
3627 			return 0;
3628 		}
3629 
3630 		if (mddev->curr_resync < max_sector) /* aborted */
3631 			bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
3632 					&sync_blocks, 1);
3633 		else /* completed sync */
3634 			conf->fullsync = 0;
3635 		bitmap_close_sync(mddev->bitmap);
3636 
3637 		return 0;
3638 	}
3639 
3640 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
3641 		return reshape_request(mddev, sector_nr, skipped);
3642 
3643 	/* No need to check resync_max as we never do more than one
3644 	 * stripe, and as resync_max will always be on a chunk boundary,
3645 	 * if the check in md_do_sync didn't fire, there is no chance
3646 	 * of overstepping resync_max here
3647 	 */
3648 
3649 	/* if there is too many failed drives and we are trying
3650 	 * to resync, then assert that we are finished, because there is
3651 	 * nothing we can do.
3652 	 */
3653 	if (mddev->degraded >= conf->max_degraded &&
3654 	    test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
3655 		sector_t rv = (mddev->size << 1) - sector_nr;
3656 		*skipped = 1;
3657 		return rv;
3658 	}
3659 	if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
3660 	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
3661 	    !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
3662 		/* we can skip this block, and probably more */
3663 		sync_blocks /= STRIPE_SECTORS;
3664 		*skipped = 1;
3665 		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
3666 	}
3667 
3668 
3669 	bitmap_cond_end_sync(mddev->bitmap, sector_nr);
3670 
3671 	pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
3672 	sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
3673 	if (sh == NULL) {
3674 		sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
3675 		/* make sure we don't swamp the stripe cache if someone else
3676 		 * is trying to get access
3677 		 */
3678 		schedule_timeout_uninterruptible(1);
3679 	}
3680 	/* Need to check if array will still be degraded after recovery/resync
3681 	 * We don't need to check the 'failed' flag as when that gets set,
3682 	 * recovery aborts.
3683 	 */
3684 	for (i=0; i<mddev->raid_disks; i++)
3685 		if (conf->disks[i].rdev == NULL)
3686 			still_degraded = 1;
3687 
3688 	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
3689 
3690 	spin_lock(&sh->lock);
3691 	set_bit(STRIPE_SYNCING, &sh->state);
3692 	clear_bit(STRIPE_INSYNC, &sh->state);
3693 	spin_unlock(&sh->lock);
3694 
3695 	handle_stripe(sh, NULL);
3696 	release_stripe(sh);
3697 
3698 	return STRIPE_SECTORS;
3699 }
3700 
3701 static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
3702 {
3703 	/* We may not be able to submit a whole bio at once as there
3704 	 * may not be enough stripe_heads available.
3705 	 * We cannot pre-allocate enough stripe_heads as we may need
3706 	 * more than exist in the cache (if we allow ever large chunks).
3707 	 * So we do one stripe head at a time and record in
3708 	 * ->bi_hw_segments how many have been done.
3709 	 *
3710 	 * We *know* that this entire raid_bio is in one chunk, so
3711 	 * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
3712 	 */
3713 	struct stripe_head *sh;
3714 	int dd_idx, pd_idx;
3715 	sector_t sector, logical_sector, last_sector;
3716 	int scnt = 0;
3717 	int remaining;
3718 	int handled = 0;
3719 
3720 	logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3721 	sector = raid5_compute_sector(	logical_sector,
3722 					conf->raid_disks,
3723 					conf->raid_disks - conf->max_degraded,
3724 					&dd_idx,
3725 					&pd_idx,
3726 					conf);
3727 	last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
3728 
3729 	for (; logical_sector < last_sector;
3730 	     logical_sector += STRIPE_SECTORS,
3731 		     sector += STRIPE_SECTORS,
3732 		     scnt++) {
3733 
3734 		if (scnt < raid_bio->bi_hw_segments)
3735 			/* already done this stripe */
3736 			continue;
3737 
3738 		sh = get_active_stripe(conf, sector, conf->raid_disks, pd_idx, 1);
3739 
3740 		if (!sh) {
3741 			/* failed to get a stripe - must wait */
3742 			raid_bio->bi_hw_segments = scnt;
3743 			conf->retry_read_aligned = raid_bio;
3744 			return handled;
3745 		}
3746 
3747 		set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
3748 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
3749 			release_stripe(sh);
3750 			raid_bio->bi_hw_segments = scnt;
3751 			conf->retry_read_aligned = raid_bio;
3752 			return handled;
3753 		}
3754 
3755 		handle_stripe(sh, NULL);
3756 		release_stripe(sh);
3757 		handled++;
3758 	}
3759 	spin_lock_irq(&conf->device_lock);
3760 	remaining = --raid_bio->bi_phys_segments;
3761 	spin_unlock_irq(&conf->device_lock);
3762 	if (remaining == 0)
3763 		bio_endio(raid_bio, 0);
3764 	if (atomic_dec_and_test(&conf->active_aligned_reads))
3765 		wake_up(&conf->wait_for_stripe);
3766 	return handled;
3767 }
3768 
3769 
3770 
3771 /*
3772  * This is our raid5 kernel thread.
3773  *
3774  * We scan the hash table for stripes which can be handled now.
3775  * During the scan, completed stripes are saved for us by the interrupt
3776  * handler, so that they will not have to wait for our next wakeup.
3777  */
3778 static void raid5d(mddev_t *mddev)
3779 {
3780 	struct stripe_head *sh;
3781 	raid5_conf_t *conf = mddev_to_conf(mddev);
3782 	int handled;
3783 
3784 	pr_debug("+++ raid5d active\n");
3785 
3786 	md_check_recovery(mddev);
3787 
3788 	handled = 0;
3789 	spin_lock_irq(&conf->device_lock);
3790 	while (1) {
3791 		struct bio *bio;
3792 
3793 		if (conf->seq_flush != conf->seq_write) {
3794 			int seq = conf->seq_flush;
3795 			spin_unlock_irq(&conf->device_lock);
3796 			bitmap_unplug(mddev->bitmap);
3797 			spin_lock_irq(&conf->device_lock);
3798 			conf->seq_write = seq;
3799 			activate_bit_delay(conf);
3800 		}
3801 
3802 		while ((bio = remove_bio_from_retry(conf))) {
3803 			int ok;
3804 			spin_unlock_irq(&conf->device_lock);
3805 			ok = retry_aligned_read(conf, bio);
3806 			spin_lock_irq(&conf->device_lock);
3807 			if (!ok)
3808 				break;
3809 			handled++;
3810 		}
3811 
3812 		sh = __get_priority_stripe(conf);
3813 
3814 		if (!sh) {
3815 			async_tx_issue_pending_all();
3816 			break;
3817 		}
3818 		spin_unlock_irq(&conf->device_lock);
3819 
3820 		handled++;
3821 		handle_stripe(sh, conf->spare_page);
3822 		release_stripe(sh);
3823 
3824 		spin_lock_irq(&conf->device_lock);
3825 	}
3826 	pr_debug("%d stripes handled\n", handled);
3827 
3828 	spin_unlock_irq(&conf->device_lock);
3829 
3830 	unplug_slaves(mddev);
3831 
3832 	pr_debug("--- raid5d inactive\n");
3833 }
3834 
3835 static ssize_t
3836 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
3837 {
3838 	raid5_conf_t *conf = mddev_to_conf(mddev);
3839 	if (conf)
3840 		return sprintf(page, "%d\n", conf->max_nr_stripes);
3841 	else
3842 		return 0;
3843 }
3844 
3845 static ssize_t
3846 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
3847 {
3848 	raid5_conf_t *conf = mddev_to_conf(mddev);
3849 	unsigned long new;
3850 	int err;
3851 
3852 	if (len >= PAGE_SIZE)
3853 		return -EINVAL;
3854 	if (!conf)
3855 		return -ENODEV;
3856 
3857 	if (strict_strtoul(page, 10, &new))
3858 		return -EINVAL;
3859 	if (new <= 16 || new > 32768)
3860 		return -EINVAL;
3861 	while (new < conf->max_nr_stripes) {
3862 		if (drop_one_stripe(conf))
3863 			conf->max_nr_stripes--;
3864 		else
3865 			break;
3866 	}
3867 	err = md_allow_write(mddev);
3868 	if (err)
3869 		return err;
3870 	while (new > conf->max_nr_stripes) {
3871 		if (grow_one_stripe(conf))
3872 			conf->max_nr_stripes++;
3873 		else break;
3874 	}
3875 	return len;
3876 }
3877 
3878 static struct md_sysfs_entry
3879 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
3880 				raid5_show_stripe_cache_size,
3881 				raid5_store_stripe_cache_size);
3882 
3883 static ssize_t
3884 raid5_show_preread_threshold(mddev_t *mddev, char *page)
3885 {
3886 	raid5_conf_t *conf = mddev_to_conf(mddev);
3887 	if (conf)
3888 		return sprintf(page, "%d\n", conf->bypass_threshold);
3889 	else
3890 		return 0;
3891 }
3892 
3893 static ssize_t
3894 raid5_store_preread_threshold(mddev_t *mddev, const char *page, size_t len)
3895 {
3896 	raid5_conf_t *conf = mddev_to_conf(mddev);
3897 	unsigned long new;
3898 	if (len >= PAGE_SIZE)
3899 		return -EINVAL;
3900 	if (!conf)
3901 		return -ENODEV;
3902 
3903 	if (strict_strtoul(page, 10, &new))
3904 		return -EINVAL;
3905 	if (new > conf->max_nr_stripes)
3906 		return -EINVAL;
3907 	conf->bypass_threshold = new;
3908 	return len;
3909 }
3910 
3911 static struct md_sysfs_entry
3912 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
3913 					S_IRUGO | S_IWUSR,
3914 					raid5_show_preread_threshold,
3915 					raid5_store_preread_threshold);
3916 
3917 static ssize_t
3918 stripe_cache_active_show(mddev_t *mddev, char *page)
3919 {
3920 	raid5_conf_t *conf = mddev_to_conf(mddev);
3921 	if (conf)
3922 		return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
3923 	else
3924 		return 0;
3925 }
3926 
3927 static struct md_sysfs_entry
3928 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
3929 
3930 static struct attribute *raid5_attrs[] =  {
3931 	&raid5_stripecache_size.attr,
3932 	&raid5_stripecache_active.attr,
3933 	&raid5_preread_bypass_threshold.attr,
3934 	NULL,
3935 };
3936 static struct attribute_group raid5_attrs_group = {
3937 	.name = NULL,
3938 	.attrs = raid5_attrs,
3939 };
3940 
3941 static int run(mddev_t *mddev)
3942 {
3943 	raid5_conf_t *conf;
3944 	int raid_disk, memory;
3945 	mdk_rdev_t *rdev;
3946 	struct disk_info *disk;
3947 	struct list_head *tmp;
3948 	int working_disks = 0;
3949 
3950 	if (mddev->level != 5 && mddev->level != 4 && mddev->level != 6) {
3951 		printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
3952 		       mdname(mddev), mddev->level);
3953 		return -EIO;
3954 	}
3955 
3956 	if (mddev->reshape_position != MaxSector) {
3957 		/* Check that we can continue the reshape.
3958 		 * Currently only disks can change, it must
3959 		 * increase, and we must be past the point where
3960 		 * a stripe over-writes itself
3961 		 */
3962 		sector_t here_new, here_old;
3963 		int old_disks;
3964 		int max_degraded = (mddev->level == 5 ? 1 : 2);
3965 
3966 		if (mddev->new_level != mddev->level ||
3967 		    mddev->new_layout != mddev->layout ||
3968 		    mddev->new_chunk != mddev->chunk_size) {
3969 			printk(KERN_ERR "raid5: %s: unsupported reshape "
3970 			       "required - aborting.\n",
3971 			       mdname(mddev));
3972 			return -EINVAL;
3973 		}
3974 		if (mddev->delta_disks <= 0) {
3975 			printk(KERN_ERR "raid5: %s: unsupported reshape "
3976 			       "(reduce disks) required - aborting.\n",
3977 			       mdname(mddev));
3978 			return -EINVAL;
3979 		}
3980 		old_disks = mddev->raid_disks - mddev->delta_disks;
3981 		/* reshape_position must be on a new-stripe boundary, and one
3982 		 * further up in new geometry must map after here in old
3983 		 * geometry.
3984 		 */
3985 		here_new = mddev->reshape_position;
3986 		if (sector_div(here_new, (mddev->chunk_size>>9)*
3987 			       (mddev->raid_disks - max_degraded))) {
3988 			printk(KERN_ERR "raid5: reshape_position not "
3989 			       "on a stripe boundary\n");
3990 			return -EINVAL;
3991 		}
3992 		/* here_new is the stripe we will write to */
3993 		here_old = mddev->reshape_position;
3994 		sector_div(here_old, (mddev->chunk_size>>9)*
3995 			   (old_disks-max_degraded));
3996 		/* here_old is the first stripe that we might need to read
3997 		 * from */
3998 		if (here_new >= here_old) {
3999 			/* Reading from the same stripe as writing to - bad */
4000 			printk(KERN_ERR "raid5: reshape_position too early for "
4001 			       "auto-recovery - aborting.\n");
4002 			return -EINVAL;
4003 		}
4004 		printk(KERN_INFO "raid5: reshape will continue\n");
4005 		/* OK, we should be able to continue; */
4006 	}
4007 
4008 
4009 	mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
4010 	if ((conf = mddev->private) == NULL)
4011 		goto abort;
4012 	if (mddev->reshape_position == MaxSector) {
4013 		conf->previous_raid_disks = conf->raid_disks = mddev->raid_disks;
4014 	} else {
4015 		conf->raid_disks = mddev->raid_disks;
4016 		conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
4017 	}
4018 
4019 	conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
4020 			      GFP_KERNEL);
4021 	if (!conf->disks)
4022 		goto abort;
4023 
4024 	conf->mddev = mddev;
4025 
4026 	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
4027 		goto abort;
4028 
4029 	if (mddev->level == 6) {
4030 		conf->spare_page = alloc_page(GFP_KERNEL);
4031 		if (!conf->spare_page)
4032 			goto abort;
4033 	}
4034 	spin_lock_init(&conf->device_lock);
4035 	mddev->queue->queue_lock = &conf->device_lock;
4036 	init_waitqueue_head(&conf->wait_for_stripe);
4037 	init_waitqueue_head(&conf->wait_for_overlap);
4038 	INIT_LIST_HEAD(&conf->handle_list);
4039 	INIT_LIST_HEAD(&conf->hold_list);
4040 	INIT_LIST_HEAD(&conf->delayed_list);
4041 	INIT_LIST_HEAD(&conf->bitmap_list);
4042 	INIT_LIST_HEAD(&conf->inactive_list);
4043 	atomic_set(&conf->active_stripes, 0);
4044 	atomic_set(&conf->preread_active_stripes, 0);
4045 	atomic_set(&conf->active_aligned_reads, 0);
4046 	conf->bypass_threshold = BYPASS_THRESHOLD;
4047 
4048 	pr_debug("raid5: run(%s) called.\n", mdname(mddev));
4049 
4050 	rdev_for_each(rdev, tmp, mddev) {
4051 		raid_disk = rdev->raid_disk;
4052 		if (raid_disk >= conf->raid_disks
4053 		    || raid_disk < 0)
4054 			continue;
4055 		disk = conf->disks + raid_disk;
4056 
4057 		disk->rdev = rdev;
4058 
4059 		if (test_bit(In_sync, &rdev->flags)) {
4060 			char b[BDEVNAME_SIZE];
4061 			printk(KERN_INFO "raid5: device %s operational as raid"
4062 				" disk %d\n", bdevname(rdev->bdev,b),
4063 				raid_disk);
4064 			working_disks++;
4065 		} else
4066 			/* Cannot rely on bitmap to complete recovery */
4067 			conf->fullsync = 1;
4068 	}
4069 
4070 	/*
4071 	 * 0 for a fully functional array, 1 or 2 for a degraded array.
4072 	 */
4073 	mddev->degraded = conf->raid_disks - working_disks;
4074 	conf->mddev = mddev;
4075 	conf->chunk_size = mddev->chunk_size;
4076 	conf->level = mddev->level;
4077 	if (conf->level == 6)
4078 		conf->max_degraded = 2;
4079 	else
4080 		conf->max_degraded = 1;
4081 	conf->algorithm = mddev->layout;
4082 	conf->max_nr_stripes = NR_STRIPES;
4083 	conf->expand_progress = mddev->reshape_position;
4084 
4085 	/* device size must be a multiple of chunk size */
4086 	mddev->size &= ~(mddev->chunk_size/1024 -1);
4087 	mddev->resync_max_sectors = mddev->size << 1;
4088 
4089 	if (conf->level == 6 && conf->raid_disks < 4) {
4090 		printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
4091 		       mdname(mddev), conf->raid_disks);
4092 		goto abort;
4093 	}
4094 	if (!conf->chunk_size || conf->chunk_size % 4) {
4095 		printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
4096 			conf->chunk_size, mdname(mddev));
4097 		goto abort;
4098 	}
4099 	if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
4100 		printk(KERN_ERR
4101 			"raid5: unsupported parity algorithm %d for %s\n",
4102 			conf->algorithm, mdname(mddev));
4103 		goto abort;
4104 	}
4105 	if (mddev->degraded > conf->max_degraded) {
4106 		printk(KERN_ERR "raid5: not enough operational devices for %s"
4107 			" (%d/%d failed)\n",
4108 			mdname(mddev), mddev->degraded, conf->raid_disks);
4109 		goto abort;
4110 	}
4111 
4112 	if (mddev->degraded > 0 &&
4113 	    mddev->recovery_cp != MaxSector) {
4114 		if (mddev->ok_start_degraded)
4115 			printk(KERN_WARNING
4116 			       "raid5: starting dirty degraded array: %s"
4117 			       "- data corruption possible.\n",
4118 			       mdname(mddev));
4119 		else {
4120 			printk(KERN_ERR
4121 			       "raid5: cannot start dirty degraded array for %s\n",
4122 			       mdname(mddev));
4123 			goto abort;
4124 		}
4125 	}
4126 
4127 	{
4128 		mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
4129 		if (!mddev->thread) {
4130 			printk(KERN_ERR
4131 				"raid5: couldn't allocate thread for %s\n",
4132 				mdname(mddev));
4133 			goto abort;
4134 		}
4135 	}
4136 	memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
4137 		 conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
4138 	if (grow_stripes(conf, conf->max_nr_stripes)) {
4139 		printk(KERN_ERR
4140 			"raid5: couldn't allocate %dkB for buffers\n", memory);
4141 		shrink_stripes(conf);
4142 		md_unregister_thread(mddev->thread);
4143 		goto abort;
4144 	} else
4145 		printk(KERN_INFO "raid5: allocated %dkB for %s\n",
4146 			memory, mdname(mddev));
4147 
4148 	if (mddev->degraded == 0)
4149 		printk("raid5: raid level %d set %s active with %d out of %d"
4150 			" devices, algorithm %d\n", conf->level, mdname(mddev),
4151 			mddev->raid_disks-mddev->degraded, mddev->raid_disks,
4152 			conf->algorithm);
4153 	else
4154 		printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
4155 			" out of %d devices, algorithm %d\n", conf->level,
4156 			mdname(mddev), mddev->raid_disks - mddev->degraded,
4157 			mddev->raid_disks, conf->algorithm);
4158 
4159 	print_raid5_conf(conf);
4160 
4161 	if (conf->expand_progress != MaxSector) {
4162 		printk("...ok start reshape thread\n");
4163 		conf->expand_lo = conf->expand_progress;
4164 		atomic_set(&conf->reshape_stripes, 0);
4165 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4166 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4167 		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4168 		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4169 		mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4170 							"%s_reshape");
4171 	}
4172 
4173 	/* read-ahead size must cover two whole stripes, which is
4174 	 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4175 	 */
4176 	{
4177 		int data_disks = conf->previous_raid_disks - conf->max_degraded;
4178 		int stripe = data_disks *
4179 			(mddev->chunk_size / PAGE_SIZE);
4180 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4181 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4182 	}
4183 
4184 	/* Ok, everything is just fine now */
4185 	if (sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
4186 		printk(KERN_WARNING
4187 		       "raid5: failed to create sysfs attributes for %s\n",
4188 		       mdname(mddev));
4189 
4190 	mddev->queue->unplug_fn = raid5_unplug_device;
4191 	mddev->queue->backing_dev_info.congested_data = mddev;
4192 	mddev->queue->backing_dev_info.congested_fn = raid5_congested;
4193 
4194 	mddev->array_sectors = 2 * mddev->size * (conf->previous_raid_disks -
4195 					    conf->max_degraded);
4196 
4197 	blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
4198 
4199 	return 0;
4200 abort:
4201 	if (conf) {
4202 		print_raid5_conf(conf);
4203 		safe_put_page(conf->spare_page);
4204 		kfree(conf->disks);
4205 		kfree(conf->stripe_hashtbl);
4206 		kfree(conf);
4207 	}
4208 	mddev->private = NULL;
4209 	printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
4210 	return -EIO;
4211 }
4212 
4213 
4214 
4215 static int stop(mddev_t *mddev)
4216 {
4217 	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4218 
4219 	md_unregister_thread(mddev->thread);
4220 	mddev->thread = NULL;
4221 	shrink_stripes(conf);
4222 	kfree(conf->stripe_hashtbl);
4223 	mddev->queue->backing_dev_info.congested_fn = NULL;
4224 	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
4225 	sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
4226 	kfree(conf->disks);
4227 	kfree(conf);
4228 	mddev->private = NULL;
4229 	return 0;
4230 }
4231 
4232 #ifdef DEBUG
4233 static void print_sh (struct seq_file *seq, struct stripe_head *sh)
4234 {
4235 	int i;
4236 
4237 	seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
4238 		   (unsigned long long)sh->sector, sh->pd_idx, sh->state);
4239 	seq_printf(seq, "sh %llu,  count %d.\n",
4240 		   (unsigned long long)sh->sector, atomic_read(&sh->count));
4241 	seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
4242 	for (i = 0; i < sh->disks; i++) {
4243 		seq_printf(seq, "(cache%d: %p %ld) ",
4244 			   i, sh->dev[i].page, sh->dev[i].flags);
4245 	}
4246 	seq_printf(seq, "\n");
4247 }
4248 
4249 static void printall (struct seq_file *seq, raid5_conf_t *conf)
4250 {
4251 	struct stripe_head *sh;
4252 	struct hlist_node *hn;
4253 	int i;
4254 
4255 	spin_lock_irq(&conf->device_lock);
4256 	for (i = 0; i < NR_HASH; i++) {
4257 		hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
4258 			if (sh->raid_conf != conf)
4259 				continue;
4260 			print_sh(seq, sh);
4261 		}
4262 	}
4263 	spin_unlock_irq(&conf->device_lock);
4264 }
4265 #endif
4266 
4267 static void status (struct seq_file *seq, mddev_t *mddev)
4268 {
4269 	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4270 	int i;
4271 
4272 	seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
4273 	seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
4274 	for (i = 0; i < conf->raid_disks; i++)
4275 		seq_printf (seq, "%s",
4276 			       conf->disks[i].rdev &&
4277 			       test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
4278 	seq_printf (seq, "]");
4279 #ifdef DEBUG
4280 	seq_printf (seq, "\n");
4281 	printall(seq, conf);
4282 #endif
4283 }
4284 
4285 static void print_raid5_conf (raid5_conf_t *conf)
4286 {
4287 	int i;
4288 	struct disk_info *tmp;
4289 
4290 	printk("RAID5 conf printout:\n");
4291 	if (!conf) {
4292 		printk("(conf==NULL)\n");
4293 		return;
4294 	}
4295 	printk(" --- rd:%d wd:%d\n", conf->raid_disks,
4296 		 conf->raid_disks - conf->mddev->degraded);
4297 
4298 	for (i = 0; i < conf->raid_disks; i++) {
4299 		char b[BDEVNAME_SIZE];
4300 		tmp = conf->disks + i;
4301 		if (tmp->rdev)
4302 		printk(" disk %d, o:%d, dev:%s\n",
4303 			i, !test_bit(Faulty, &tmp->rdev->flags),
4304 			bdevname(tmp->rdev->bdev,b));
4305 	}
4306 }
4307 
4308 static int raid5_spare_active(mddev_t *mddev)
4309 {
4310 	int i;
4311 	raid5_conf_t *conf = mddev->private;
4312 	struct disk_info *tmp;
4313 
4314 	for (i = 0; i < conf->raid_disks; i++) {
4315 		tmp = conf->disks + i;
4316 		if (tmp->rdev
4317 		    && !test_bit(Faulty, &tmp->rdev->flags)
4318 		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
4319 			unsigned long flags;
4320 			spin_lock_irqsave(&conf->device_lock, flags);
4321 			mddev->degraded--;
4322 			spin_unlock_irqrestore(&conf->device_lock, flags);
4323 		}
4324 	}
4325 	print_raid5_conf(conf);
4326 	return 0;
4327 }
4328 
4329 static int raid5_remove_disk(mddev_t *mddev, int number)
4330 {
4331 	raid5_conf_t *conf = mddev->private;
4332 	int err = 0;
4333 	mdk_rdev_t *rdev;
4334 	struct disk_info *p = conf->disks + number;
4335 
4336 	print_raid5_conf(conf);
4337 	rdev = p->rdev;
4338 	if (rdev) {
4339 		if (test_bit(In_sync, &rdev->flags) ||
4340 		    atomic_read(&rdev->nr_pending)) {
4341 			err = -EBUSY;
4342 			goto abort;
4343 		}
4344 		/* Only remove non-faulty devices if recovery
4345 		 * isn't possible.
4346 		 */
4347 		if (!test_bit(Faulty, &rdev->flags) &&
4348 		    mddev->degraded <= conf->max_degraded) {
4349 			err = -EBUSY;
4350 			goto abort;
4351 		}
4352 		p->rdev = NULL;
4353 		synchronize_rcu();
4354 		if (atomic_read(&rdev->nr_pending)) {
4355 			/* lost the race, try later */
4356 			err = -EBUSY;
4357 			p->rdev = rdev;
4358 		}
4359 	}
4360 abort:
4361 
4362 	print_raid5_conf(conf);
4363 	return err;
4364 }
4365 
4366 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
4367 {
4368 	raid5_conf_t *conf = mddev->private;
4369 	int err = -EEXIST;
4370 	int disk;
4371 	struct disk_info *p;
4372 	int first = 0;
4373 	int last = conf->raid_disks - 1;
4374 
4375 	if (mddev->degraded > conf->max_degraded)
4376 		/* no point adding a device */
4377 		return -EINVAL;
4378 
4379 	if (rdev->raid_disk >= 0)
4380 		first = last = rdev->raid_disk;
4381 
4382 	/*
4383 	 * find the disk ... but prefer rdev->saved_raid_disk
4384 	 * if possible.
4385 	 */
4386 	if (rdev->saved_raid_disk >= 0 &&
4387 	    rdev->saved_raid_disk >= first &&
4388 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
4389 		disk = rdev->saved_raid_disk;
4390 	else
4391 		disk = first;
4392 	for ( ; disk <= last ; disk++)
4393 		if ((p=conf->disks + disk)->rdev == NULL) {
4394 			clear_bit(In_sync, &rdev->flags);
4395 			rdev->raid_disk = disk;
4396 			err = 0;
4397 			if (rdev->saved_raid_disk != disk)
4398 				conf->fullsync = 1;
4399 			rcu_assign_pointer(p->rdev, rdev);
4400 			break;
4401 		}
4402 	print_raid5_conf(conf);
4403 	return err;
4404 }
4405 
4406 static int raid5_resize(mddev_t *mddev, sector_t sectors)
4407 {
4408 	/* no resync is happening, and there is enough space
4409 	 * on all devices, so we can resize.
4410 	 * We need to make sure resync covers any new space.
4411 	 * If the array is shrinking we should possibly wait until
4412 	 * any io in the removed space completes, but it hardly seems
4413 	 * worth it.
4414 	 */
4415 	raid5_conf_t *conf = mddev_to_conf(mddev);
4416 
4417 	sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
4418 	mddev->array_sectors = sectors * (mddev->raid_disks
4419 					  - conf->max_degraded);
4420 	set_capacity(mddev->gendisk, mddev->array_sectors);
4421 	mddev->changed = 1;
4422 	if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
4423 		mddev->recovery_cp = mddev->size << 1;
4424 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4425 	}
4426 	mddev->size = sectors /2;
4427 	mddev->resync_max_sectors = sectors;
4428 	return 0;
4429 }
4430 
4431 #ifdef CONFIG_MD_RAID5_RESHAPE
4432 static int raid5_check_reshape(mddev_t *mddev)
4433 {
4434 	raid5_conf_t *conf = mddev_to_conf(mddev);
4435 	int err;
4436 
4437 	if (mddev->delta_disks < 0 ||
4438 	    mddev->new_level != mddev->level)
4439 		return -EINVAL; /* Cannot shrink array or change level yet */
4440 	if (mddev->delta_disks == 0)
4441 		return 0; /* nothing to do */
4442 
4443 	/* Can only proceed if there are plenty of stripe_heads.
4444 	 * We need a minimum of one full stripe,, and for sensible progress
4445 	 * it is best to have about 4 times that.
4446 	 * If we require 4 times, then the default 256 4K stripe_heads will
4447 	 * allow for chunk sizes up to 256K, which is probably OK.
4448 	 * If the chunk size is greater, user-space should request more
4449 	 * stripe_heads first.
4450 	 */
4451 	if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
4452 	    (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
4453 		printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
4454 		       (mddev->chunk_size / STRIPE_SIZE)*4);
4455 		return -ENOSPC;
4456 	}
4457 
4458 	err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
4459 	if (err)
4460 		return err;
4461 
4462 	if (mddev->degraded > conf->max_degraded)
4463 		return -EINVAL;
4464 	/* looks like we might be able to manage this */
4465 	return 0;
4466 }
4467 
4468 static int raid5_start_reshape(mddev_t *mddev)
4469 {
4470 	raid5_conf_t *conf = mddev_to_conf(mddev);
4471 	mdk_rdev_t *rdev;
4472 	struct list_head *rtmp;
4473 	int spares = 0;
4474 	int added_devices = 0;
4475 	unsigned long flags;
4476 
4477 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
4478 		return -EBUSY;
4479 
4480 	rdev_for_each(rdev, rtmp, mddev)
4481 		if (rdev->raid_disk < 0 &&
4482 		    !test_bit(Faulty, &rdev->flags))
4483 			spares++;
4484 
4485 	if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
4486 		/* Not enough devices even to make a degraded array
4487 		 * of that size
4488 		 */
4489 		return -EINVAL;
4490 
4491 	atomic_set(&conf->reshape_stripes, 0);
4492 	spin_lock_irq(&conf->device_lock);
4493 	conf->previous_raid_disks = conf->raid_disks;
4494 	conf->raid_disks += mddev->delta_disks;
4495 	conf->expand_progress = 0;
4496 	conf->expand_lo = 0;
4497 	spin_unlock_irq(&conf->device_lock);
4498 
4499 	/* Add some new drives, as many as will fit.
4500 	 * We know there are enough to make the newly sized array work.
4501 	 */
4502 	rdev_for_each(rdev, rtmp, mddev)
4503 		if (rdev->raid_disk < 0 &&
4504 		    !test_bit(Faulty, &rdev->flags)) {
4505 			if (raid5_add_disk(mddev, rdev) == 0) {
4506 				char nm[20];
4507 				set_bit(In_sync, &rdev->flags);
4508 				added_devices++;
4509 				rdev->recovery_offset = 0;
4510 				sprintf(nm, "rd%d", rdev->raid_disk);
4511 				if (sysfs_create_link(&mddev->kobj,
4512 						      &rdev->kobj, nm))
4513 					printk(KERN_WARNING
4514 					       "raid5: failed to create "
4515 					       " link %s for %s\n",
4516 					       nm, mdname(mddev));
4517 			} else
4518 				break;
4519 		}
4520 
4521 	spin_lock_irqsave(&conf->device_lock, flags);
4522 	mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
4523 	spin_unlock_irqrestore(&conf->device_lock, flags);
4524 	mddev->raid_disks = conf->raid_disks;
4525 	mddev->reshape_position = 0;
4526 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
4527 
4528 	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4529 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4530 	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4531 	set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4532 	mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4533 						"%s_reshape");
4534 	if (!mddev->sync_thread) {
4535 		mddev->recovery = 0;
4536 		spin_lock_irq(&conf->device_lock);
4537 		mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
4538 		conf->expand_progress = MaxSector;
4539 		spin_unlock_irq(&conf->device_lock);
4540 		return -EAGAIN;
4541 	}
4542 	md_wakeup_thread(mddev->sync_thread);
4543 	md_new_event(mddev);
4544 	return 0;
4545 }
4546 #endif
4547 
4548 static void end_reshape(raid5_conf_t *conf)
4549 {
4550 	struct block_device *bdev;
4551 
4552 	if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
4553 		conf->mddev->array_sectors = 2 * conf->mddev->size *
4554 			(conf->raid_disks - conf->max_degraded);
4555 		set_capacity(conf->mddev->gendisk, conf->mddev->array_sectors);
4556 		conf->mddev->changed = 1;
4557 
4558 		bdev = bdget_disk(conf->mddev->gendisk, 0);
4559 		if (bdev) {
4560 			mutex_lock(&bdev->bd_inode->i_mutex);
4561 			i_size_write(bdev->bd_inode,
4562 				     (loff_t)conf->mddev->array_sectors << 9);
4563 			mutex_unlock(&bdev->bd_inode->i_mutex);
4564 			bdput(bdev);
4565 		}
4566 		spin_lock_irq(&conf->device_lock);
4567 		conf->expand_progress = MaxSector;
4568 		spin_unlock_irq(&conf->device_lock);
4569 		conf->mddev->reshape_position = MaxSector;
4570 
4571 		/* read-ahead size must cover two whole stripes, which is
4572 		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4573 		 */
4574 		{
4575 			int data_disks = conf->previous_raid_disks - conf->max_degraded;
4576 			int stripe = data_disks *
4577 				(conf->mddev->chunk_size / PAGE_SIZE);
4578 			if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4579 				conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4580 		}
4581 	}
4582 }
4583 
4584 static void raid5_quiesce(mddev_t *mddev, int state)
4585 {
4586 	raid5_conf_t *conf = mddev_to_conf(mddev);
4587 
4588 	switch(state) {
4589 	case 2: /* resume for a suspend */
4590 		wake_up(&conf->wait_for_overlap);
4591 		break;
4592 
4593 	case 1: /* stop all writes */
4594 		spin_lock_irq(&conf->device_lock);
4595 		conf->quiesce = 1;
4596 		wait_event_lock_irq(conf->wait_for_stripe,
4597 				    atomic_read(&conf->active_stripes) == 0 &&
4598 				    atomic_read(&conf->active_aligned_reads) == 0,
4599 				    conf->device_lock, /* nothing */);
4600 		spin_unlock_irq(&conf->device_lock);
4601 		break;
4602 
4603 	case 0: /* re-enable writes */
4604 		spin_lock_irq(&conf->device_lock);
4605 		conf->quiesce = 0;
4606 		wake_up(&conf->wait_for_stripe);
4607 		wake_up(&conf->wait_for_overlap);
4608 		spin_unlock_irq(&conf->device_lock);
4609 		break;
4610 	}
4611 }
4612 
4613 static struct mdk_personality raid6_personality =
4614 {
4615 	.name		= "raid6",
4616 	.level		= 6,
4617 	.owner		= THIS_MODULE,
4618 	.make_request	= make_request,
4619 	.run		= run,
4620 	.stop		= stop,
4621 	.status		= status,
4622 	.error_handler	= error,
4623 	.hot_add_disk	= raid5_add_disk,
4624 	.hot_remove_disk= raid5_remove_disk,
4625 	.spare_active	= raid5_spare_active,
4626 	.sync_request	= sync_request,
4627 	.resize		= raid5_resize,
4628 #ifdef CONFIG_MD_RAID5_RESHAPE
4629 	.check_reshape	= raid5_check_reshape,
4630 	.start_reshape  = raid5_start_reshape,
4631 #endif
4632 	.quiesce	= raid5_quiesce,
4633 };
4634 static struct mdk_personality raid5_personality =
4635 {
4636 	.name		= "raid5",
4637 	.level		= 5,
4638 	.owner		= THIS_MODULE,
4639 	.make_request	= make_request,
4640 	.run		= run,
4641 	.stop		= stop,
4642 	.status		= status,
4643 	.error_handler	= error,
4644 	.hot_add_disk	= raid5_add_disk,
4645 	.hot_remove_disk= raid5_remove_disk,
4646 	.spare_active	= raid5_spare_active,
4647 	.sync_request	= sync_request,
4648 	.resize		= raid5_resize,
4649 #ifdef CONFIG_MD_RAID5_RESHAPE
4650 	.check_reshape	= raid5_check_reshape,
4651 	.start_reshape  = raid5_start_reshape,
4652 #endif
4653 	.quiesce	= raid5_quiesce,
4654 };
4655 
4656 static struct mdk_personality raid4_personality =
4657 {
4658 	.name		= "raid4",
4659 	.level		= 4,
4660 	.owner		= THIS_MODULE,
4661 	.make_request	= make_request,
4662 	.run		= run,
4663 	.stop		= stop,
4664 	.status		= status,
4665 	.error_handler	= error,
4666 	.hot_add_disk	= raid5_add_disk,
4667 	.hot_remove_disk= raid5_remove_disk,
4668 	.spare_active	= raid5_spare_active,
4669 	.sync_request	= sync_request,
4670 	.resize		= raid5_resize,
4671 #ifdef CONFIG_MD_RAID5_RESHAPE
4672 	.check_reshape	= raid5_check_reshape,
4673 	.start_reshape  = raid5_start_reshape,
4674 #endif
4675 	.quiesce	= raid5_quiesce,
4676 };
4677 
4678 static int __init raid5_init(void)
4679 {
4680 	int e;
4681 
4682 	e = raid6_select_algo();
4683 	if ( e )
4684 		return e;
4685 	register_md_personality(&raid6_personality);
4686 	register_md_personality(&raid5_personality);
4687 	register_md_personality(&raid4_personality);
4688 	return 0;
4689 }
4690 
4691 static void raid5_exit(void)
4692 {
4693 	unregister_md_personality(&raid6_personality);
4694 	unregister_md_personality(&raid5_personality);
4695 	unregister_md_personality(&raid4_personality);
4696 }
4697 
4698 module_init(raid5_init);
4699 module_exit(raid5_exit);
4700 MODULE_LICENSE("GPL");
4701 MODULE_ALIAS("md-personality-4"); /* RAID5 */
4702 MODULE_ALIAS("md-raid5");
4703 MODULE_ALIAS("md-raid4");
4704 MODULE_ALIAS("md-level-5");
4705 MODULE_ALIAS("md-level-4");
4706 MODULE_ALIAS("md-personality-8"); /* RAID6 */
4707 MODULE_ALIAS("md-raid6");
4708 MODULE_ALIAS("md-level-6");
4709 
4710 /* This used to be two separate modules, they were: */
4711 MODULE_ALIAS("raid5");
4712 MODULE_ALIAS("raid6");
4713