summaryrefslogtreecommitdiffstats
path: root/fs/exofs/ore_raid.c
blob: 27cbdb6976495f5f830ca473e9b844fb1a2bd29d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
/*
 * Copyright (C) 2011
 * Boaz Harrosh <ooo@electrozaur.com>
 *
 * This file is part of the objects raid engine (ore).
 *
 * It is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * You should have received a copy of the GNU General Public License
 * along with "ore". If not, write to the Free Software Foundation, Inc:
 *	"Free Software Foundation <info@fsf.org>"
 */

#include <linux/gfp.h>
#include <linux/async_tx.h>

#include "ore_raid.h"

#undef ORE_DBGMSG2
#define ORE_DBGMSG2 ORE_DBGMSG

static struct page *_raid_page_alloc(void)
{
	return alloc_page(GFP_KERNEL);
}

static void _raid_page_free(struct page *p)
{
	__free_page(p);
}

/* This struct is forward declare in ore_io_state, but is private to here.
 * It is put on ios->sp2d for RAID5/6 writes only. See _gen_xor_unit.
 *
 * __stripe_pages_2d is a 2d array of pages, and it is also a corner turn.
 * Ascending page index access is sp2d(p-minor, c-major). But storage is
 * sp2d[p-minor][c-major], so it can be properlly presented to the async-xor
 * API.
 */
struct __stripe_pages_2d {
	/* Cache some hot path repeated calculations */
	unsigned parity;
	unsigned data_devs;
	unsigned pages_in_unit;

	bool needed ;

	/* Array size is pages_in_unit (layout->stripe_unit / PAGE_SIZE) */
	struct __1_page_stripe {
		bool alloc;
		unsigned write_count;
		struct async_submit_ctl submit;
		struct dma_async_tx_descriptor *tx;

		/* The size of this array is data_devs + parity */
		struct page **pages;
		struct page **scribble;
		/* bool array, size of this array is data_devs */
		char *page_is_read;
	} _1p_stripes[];
};

/* This can get bigger then a page. So support multiple page allocations
 * _sp2d_free should be called even if _sp2d_alloc fails (by returning
 * none-zero).
 */
static int _sp2d_alloc(unsigned pages_in_unit, unsigned group_width,
		       unsigned parity, struct __stripe_pages_2d **psp2d)
{
	struct __stripe_pages_2d *sp2d;
	unsigned data_devs = group_width - parity;
	struct _alloc_all_bytes {
		struct __alloc_stripe_pages_2d {
			struct __stripe_pages_2d sp2d;
			struct __1_page_stripe _1p_stripes[pages_in_unit];
		} __asp2d;
		struct __alloc_1p_arrays {
			struct page *pages[group_width];
			struct page *scribble[group_width];
			char page_is_read[data_devs];
		} __a1pa[pages_in_unit];
	} *_aab;
	struct __alloc_1p_arrays *__a1pa;
	struct __alloc_1p_arrays *__a1pa_end;
	const unsigned sizeof__a1pa = sizeof(_aab->__a1pa[0]);
	unsigned num_a1pa, alloc_size, i;

	/* FIXME: check these numbers in ore_verify_layout */
	BUG_ON(sizeof(_aab->__asp2d) > PAGE_SIZE);
	BUG_ON(sizeof__a1pa > PAGE_SIZE);

	if (sizeof(*_aab) > PAGE_SIZE) {
		num_a1pa = (PAGE_SIZE - sizeof(_aab->__asp2d)) / sizeof__a1pa;
		alloc_size = sizeof(_aab->__asp2d) + sizeof__a1pa * num_a1pa;
	} else {
		num_a1pa = pages_in_unit;
		alloc_size = sizeof(*_aab);
	}

	_aab = kzalloc(alloc_size, GFP_KERNEL);
	if (unlikely(!_aab)) {
		ORE_DBGMSG("!! Failed to alloc sp2d size=%d\n", alloc_size);
		return -ENOMEM;
	}

	sp2d = &_aab->__asp2d.sp2d;
	*psp2d = sp2d; /* From here Just call _sp2d_free */

	__a1pa = _aab->__a1pa;
	__a1pa_end = __a1pa + num_a1pa;

	for (i = 0; i < pages_in_unit; ++i) {
		if (unlikely(__a1pa >= __a1pa_end)) {
			num_a1pa = min_t(unsigned, PAGE_SIZE / sizeof__a1pa,
							pages_in_unit - i);

			__a1pa = kcalloc(num_a1pa, sizeof__a1pa, GFP_KERNEL);
			if (unlikely(!__a1pa)) {
				ORE_DBGMSG("!! Failed to _alloc_1p_arrays=%d\n",
					   num_a1pa);
				return -ENOMEM;
			}
			__a1pa_end = __a1pa + num_a1pa;
			/* First *pages is marked for kfree of the buffer */
			sp2d->_1p_stripes[i].alloc = true;
		}

		sp2d->_1p_stripes[i].pages = __a1pa->pages;
		sp2d->_1p_stripes[i].scribble = __a1pa->scribble ;
		sp2d->_1p_stripes[i].page_is_read = __a1pa->page_is_read;
		++__a1pa;
	}

	sp2d->parity = parity;
	sp2d->data_devs = data_devs;
	sp2d->pages_in_unit = pages_in_unit;
	return 0;
}

static void _sp2d_reset(struct __stripe_pages_2d *sp2d,
			const struct _ore_r4w_op *r4w, void *priv)
{
	unsigned data_devs = sp2d->data_devs;
	unsigned group_width = data_devs + sp2d->parity;
	int p, c;

	if (!sp2d->needed)
		return;

	for (c = data_devs - 1; c >= 0; --c)
		for (p = sp2d->pages_in_unit - 1; p >= 0; --p) {
			struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

			if (_1ps->page_is_read[c]) {
				struct page *page = _1ps->pages[c];

				r4w->put_page(priv, page);
				_1ps->page_is_read[c] = false;
			}
		}

	for (p = 0; p < sp2d->pages_in_unit; p++) {
		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

		memset(_1ps->pages, 0, group_width * sizeof(*_1ps->pages));
		_1ps->write_count = 0;
		_1ps->tx = NULL;
	}

	sp2d->needed = false;
}

static void _sp2d_free(struct __stripe_pages_2d *sp2d)
{
	unsigned i;

	if (!sp2d)
		return;

	for (i = 0; i < sp2d->pages_in_unit; ++i) {
		if (sp2d->_1p_stripes[i].alloc)
			kfree(sp2d->_1p_stripes[i].pages);
	}

	kfree(sp2d);
}

static unsigned _sp2d_min_pg(struct __stripe_pages_2d *sp2d)
{
	unsigned p;

	for (p = 0; p < sp2d->pages_in_unit; p++) {
		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

		if (_1ps->write_count)
			return p;
	}

	return ~0;
}

static unsigned _sp2d_max_pg(struct __stripe_pages_2d *sp2d)
{
	int p;

	for (p = sp2d->pages_in_unit - 1; p >= 0; --p) {
		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

		if (_1ps->write_count)
			return p;
	}

	return ~0;
}

static void _gen_xor_unit(struct __stripe_pages_2d *sp2d)
{
	unsigned p;
	unsigned tx_flags = ASYNC_TX_ACK;

	if (sp2d->parity == 1)
		tx_flags |= ASYNC_TX_XOR_ZERO_DST;

	for (p = 0; p < sp2d->pages_in_unit; p++) {
		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

		if (!_1ps->write_count)
			continue;

		init_async_submit(&_1ps->submit, tx_flags,
			NULL, NULL, NULL, (addr_conv_t *)_1ps->scribble);

		if (sp2d->parity == 1)
			_1ps->tx = async_xor(_1ps->pages[sp2d->data_devs],
						_1ps->pages, 0, sp2d->data_devs,
						PAGE_SIZE, &_1ps->submit);
		else /* parity == 2 */
			_1ps->tx = async_gen_syndrome(_1ps->pages, 0,
						sp2d->data_devs + sp2d->parity,
						PAGE_SIZE, &_1ps->submit);
	}

	for (p = 0; p < sp2d->pages_in_unit; p++) {
		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
		/* NOTE: We wait for HW synchronously (I don't have such HW
		 * to test with.) Is parallelism needed with today's multi
		 * cores?
		 */
		async_tx_issue_pending(_1ps->tx);
	}
}

void _ore_add_stripe_page(struct __stripe_pages_2d *sp2d,
		       struct ore_striping_info *si, struct page *page)
{
	struct __1_page_stripe *_1ps;

	sp2d->needed = true;

	_1ps = &sp2d->_1p_stripes[si->cur_pg];
	_1ps->pages[si->cur_comp] = page;
	++_1ps->write_count;

	si->cur_pg = (si->cur_pg + 1) % sp2d->pages_in_unit;
	/* si->cur_comp is advanced outside at main loop */
}

void _ore_add_sg_seg(struct ore_per_dev_state *per_dev, unsigned cur_len,
		     bool not_last)
{
	struct osd_sg_entry *sge;

	ORE_DBGMSG("dev=%d cur_len=0x%x not_last=%d cur_sg=%d "
		     "offset=0x%llx length=0x%x last_sgs_total=0x%x\n",
		     per_dev->dev, cur_len, not_last, per_dev->cur_sg,
		     _LLU(per_dev->offset), per_dev->length,
		     per_dev->last_sgs_total);

	if (!per_dev->cur_sg) {
		sge = per_dev->sglist;

		/* First time we prepare two entries */
		if (per_dev->length) {
			++per_dev->cur_sg;
			sge->offset = per_dev->offset;
			sge->len = per_dev->length;
		} else {
			/* Here the parity is the first unit of this object.
			 * This happens every time we reach a parity device on
			 * the same stripe as the per_dev->offset. We need to
			 * just skip this unit.
			 */
			per_dev->offset += cur_len;
			return;
		}
	} else {
		/* finalize the last one */
		sge = &per_dev->sglist[per_dev->cur_sg - 1];
		sge->len = per_dev->length - per_dev->last_sgs_total;
	}

	if (not_last) {
		/* Partly prepare the next one */
		struct osd_sg_entry *next_sge = sge + 1;

		++per_dev->cur_sg;
		next_sge->offset = sge->offset + sge->len + cur_len;
		/* Save cur len so we know how mutch was added next time */
		per_dev->last_sgs_total = per_dev->length;
		next_sge->len = 0;
	} else if (!sge->len) {
		/* Optimize for when the last unit is a parity */
		--per_dev->cur_sg;
	}
}

static int _alloc_read_4_write(struct ore_io_state *ios)
{
	struct ore_layout *layout = ios->layout;
	int ret;
	/* We want to only read those pages not in cache so worst case
	 * is a stripe populated with every other page
	 */
	unsigned sgs_per_dev = ios->sp2d->pages_in_unit + 2;

	ret = _ore_get_io_state(layout, ios->oc,
				layout->group_width * layout->mirrors_p1,
				sgs_per_dev, 0, &ios->ios_read_4_write);
	return ret;
}

/* @si contains info of the to-be-inserted page. Update of @si should be
 * maintained by caller. Specificaly si->dev, si->obj_offset, ...
 */
static int _add_to_r4w(struct ore_io_state *ios, struct ore_striping_info *si,
		       struct page *page, unsigned pg_len)
{
	struct request_queue *q;
	struct ore_per_dev_state *per_dev;
	struct ore_io_state *read_ios;
	unsigned first_dev = si->dev - (si->dev %
			  (ios->layout->group_width * ios->layout->mirrors_p1));
	unsigned comp = si->dev - first_dev;
	unsigned added_len;

	if (!ios->ios_read_4_write) {
		int ret = _alloc_read_4_write(ios);

		if (unlikely(ret))
			return ret;
	}

	read_ios = ios->ios_read_4_write;
	read_ios->numdevs = ios->layout->group_width * ios->layout->mirrors_p1;

	per_dev = &read_ios->per_dev[comp];
	if (!per_dev->length) {
		per_dev->bio = bio_kmalloc(GFP_KERNEL,
					   ios->sp2d->pages_in_unit);
		if (unlikely(!per_dev->bio)) {
			ORE_DBGMSG("Failed to allocate BIO size=%u\n",
				     ios->sp2d->pages_in_unit);
			return -ENOMEM;
		}
		per_dev->offset = si->obj_offset;
		per_dev->dev = si->dev;
	} else if (si->obj_offset != (per_dev->offset + per_dev->length)) {
		u64 gap = si->obj_offset - (per_dev->offset + per_dev->length);

		_ore_add_sg_seg(per_dev, gap, true);
	}
	q = osd_request_queue(ore_comp_dev(read_ios->oc, per_dev->dev));
	added_len = bio_add_pc_page(q, per_dev->bio, page, pg_len,
				    si->obj_offset % PAGE_SIZE);
	if (unlikely(added_len != pg_len)) {
		ORE_DBGMSG("Failed to bio_add_pc_page bi_vcnt=%d\n",
			      per_dev->bio->bi_vcnt);
		return -ENOMEM;
	}

	per_dev->length += pg_len;
	return 0;
}

/* read the beginning of an unaligned first page */
static int _add_to_r4w_first_page(struct ore_io_state *ios, struct page *page)
{
	struct ore_striping_info si;
	unsigned pg_len;

	ore_calc_stripe_info(ios->layout, ios->offset, 0, &si);

	pg_len = si.obj_offset % PAGE_SIZE;
	si.obj_offset -= pg_len;

	ORE_DBGMSG("offset=0x%llx len=0x%x index=0x%lx dev=%x\n",
		   _LLU(si.obj_offset), pg_len, page->index, si.dev);

	return _add_to_r4w(ios, &si, page, pg_len);
}

/* read the end of an incomplete last page */
static int _add_to_r4w_last_page(struct ore_io_state *ios, u64 *offset)
{
	struct ore_striping_info si;
	struct page *page;
	unsigned pg_len, p, c;

	ore_calc_stripe_info(ios->layout, *offset, 0, &si);

	p = si.cur_pg;
	c = si.cur_comp;
	page = ios->sp2d->_1p_stripes[p].pages[c];

	pg_len = PAGE_SIZE - (si.unit_off % PAGE_SIZE);
	*offset += pg_len;

	ORE_DBGMSG("p=%d, c=%d next-offset=0x%llx len=0x%x dev=%x par_dev=%d\n",
		   p, c, _LLU(*offset), pg_len, si.dev, si.par_dev);

	BUG_ON(!page);

	return _add_to_r4w(ios, &si, page, pg_len);
}

static void _mark_read4write_pages_uptodate(struct ore_io_state *ios, int ret)
{
	struct bio_vec *bv;
	unsigned i, d;

	/* loop on all devices all pages */
	for (d = 0; d < ios->numdevs; d++) {
		struct bio *bio = ios->per_dev[d].bio;

		if (!bio)
			continue;

		bio_for_each_segment_all(bv, bio, i) {
			struct page *page = bv->bv_page;

			SetPageUptodate(page);
			if (PageError(page))
				ClearPageError(page);
		}
	}
}

/* read_4_write is hacked to read the start of the first stripe and/or
 * the end of the last stripe. If needed, with an sg-gap at each device/page.
 * It is assumed to be called after the to_be_written pages of the first stripe
 * are populating ios->sp2d[][]
 *
 * NOTE: We call ios->r4w->lock_fn for all pages needed for parity calculations
 * These pages are held at sp2d[p].pages[c] but with
 * sp2d[p].page_is_read[c] = true. At _sp2d_reset these pages are
 * ios->r4w->lock_fn(). The ios->r4w->lock_fn might signal that the page is
 * @uptodate=true, so we don't need to read it, only unlock, after IO.
 *
 * TODO: The read_4_write should calc a need_to_read_pages_count, if bigger then
 * to-be-written count, we should consider the xor-in-place mode.
 * need_to_read_pages_count is the actual number of pages not present in cache.
 * maybe "devs_in_group - ios->sp2d[p].write_count" is a good enough
 * approximation? In this mode the read pages are put in the empty places of
 * ios->sp2d[p][*], xor is calculated the same way. These pages are
 * allocated/freed and don't go through cache
 */
static int _read_4_write_first_stripe(struct ore_io_state *ios)
{
	struct ore_striping_info read_si;
	struct __stripe_pages_2d *sp2d = ios->sp2d;
	u64 offset = ios->si.first_stripe_start;
	unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;

	if (offset == ios->offset) /* Go to start collect $200 */
		goto read_last_stripe;

	min_p = _sp2d_min_pg(sp2d);
	max_p = _sp2d_max_pg(sp2d);

	ORE_DBGMSG("stripe_start=0x%llx ios->offset=0x%llx min_p=%d max_p=%d\n",
		   offset, ios->offset, min_p, max_p);

	for (c = 0; ; c++) {
		ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
		read_si.obj_offset += min_p * PAGE_SIZE;
		offset += min_p * PAGE_SIZE;
		for (p = min_p; p <= max_p; p++) {
			struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
			struct page **pp = &_1ps->pages[c];
			bool uptodate;

			if (*pp) {
				if (ios->offset % PAGE_SIZE)
					/* Read the remainder of the page */
					_add_to_r4w_first_page(ios, *pp);
				/* to-be-written pages start here */
				goto read_last_stripe;
			}

			*pp = ios->r4w->get_page(ios->private, offset,
						 &uptodate);
			if (unlikely(!*pp))
				return -ENOMEM;

			if (!uptodate)
				_add_to_r4w(ios, &read_si, *pp, PAGE_SIZE);

			/* Mark read-pages to be cache_released */
			_1ps->page_is_read[c] = true;
			read_si.obj_offset += PAGE_SIZE;
			offset += PAGE_SIZE;
		}
		offset += (sp2d->pages_in_unit - p) * PAGE_SIZE;
	}

read_last_stripe:
	return 0;
}

static int _read_4_write_last_stripe(struct ore_io_state *ios)
{
	struct ore_striping_info read_si;
	struct __stripe_pages_2d *sp2d = ios->sp2d;
	u64 offset;
	u64 last_stripe_end;
	unsigned bytes_in_stripe = ios->si.bytes_in_stripe;
	unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;

	offset = ios->offset + ios->length;
	if (offset % PAGE_SIZE)
		_add_to_r4w_last_page(ios, &offset);
		/* offset will be aligned to next page */

	last_stripe_end = div_u64(offset + bytes_in_stripe - 1, bytes_in_stripe)
				 * bytes_in_stripe;
	if (offset == last_stripe_end) /* Optimize for the aligned case */
		goto read_it;

	ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
	p = read_si.cur_pg;
	c = read_si.cur_comp;

	if (min_p == sp2d->pages_in_unit) {
		/* Didn't do it yet */
		min_p = _sp2d_min_pg(sp2d);
		max_p = _sp2d_max_pg(sp2d);
	}

	ORE_DBGMSG("offset=0x%llx stripe_end=0x%llx min_p=%d max_p=%d\n",
		   offset, last_stripe_end, min_p, max_p);

	while (offset < last_stripe_end) {
		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

		if ((min_p <= p) && (p <= max_p)) {
			struct page *page;
			bool uptodate;

			BUG_ON(_1ps->pages[c]);
			page = ios->r4w->get_page(ios->private, offset,
						  &uptodate);
			if (unlikely(!page))
				return -ENOMEM;

			_1ps->pages[c] = page;
			/* Mark read-pages to be cache_released */
			_1ps->page_is_read[c] = true;
			if (!uptodate)
				_add_to_r4w(ios, &read_si, page, PAGE_SIZE);
		}

		offset += PAGE_SIZE;
		if (p == (sp2d->pages_in_unit - 1)) {
			++c;
			p = 0;
			ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
		} else {
			read_si.obj_offset += PAGE_SIZE;
			++p;
		}
	}

read_it:
	return 0;
}

static int _read_4_write_execute(struct ore_io_state *ios)
{
	struct ore_io_state *ios_read;
	unsigned i;
	int ret;

	ios_read = ios->ios_read_4_write;
	if (!ios_read)
		return 0;

	/* FIXME: Ugly to signal _sbi_read_mirror that we have bio(s). Change
	 * to check for per_dev->bio
	 */
	ios_read->pages = ios->pages;

	/* Now read these devices */
	for (i = 0; i < ios_read->numdevs; i += ios_read->layout->mirrors_p1) {
		ret = _ore_read_mirror(ios_read, i);
		if (unlikely(ret))
			return ret;
	}

	ret = ore_io_execute(ios_read); /* Synchronus execution */
	if (unlikely(ret)) {
		ORE_DBGMSG("!! ore_io_execute => %d\n", ret);
		return ret;
	}

	_mark_read4write_pages_uptodate(ios_read, ret);
	ore_put_io_state(ios_read);
	ios->ios_read_4_write = NULL; /* Might need a reuse at last stripe */
	return 0;
}

/* In writes @cur_len means length left. .i.e cur_len==0 is the last parity U */
int _ore_add_parity_unit(struct ore_io_state *ios,
			    struct ore_striping_info *si,
			    struct ore_per_dev_state *per_dev,
			    unsigned cur_len, bool do_xor)
{
	if (ios->reading) {
		if (per_dev->cur_sg >= ios->sgs_per_dev) {
			ORE_DBGMSG("cur_sg(%d) >= sgs_per_dev(%d)\n" ,
				per_dev->cur_sg, ios->sgs_per_dev);
			return -ENOMEM;
		}
		_ore_add_sg_seg(per_dev, cur_len, true);
	} else {
		struct __stripe_pages_2d *sp2d = ios->sp2d;
		struct page **pages = ios->parity_pages + ios->cur_par_page;
		unsigned num_pages;
		unsigned array_start = 0;
		unsigned i;
		int ret;

		si->cur_pg = _sp2d_min_pg(sp2d);
		num_pages  = _sp2d_max_pg(sp2d) + 1 - si->cur_pg;

		if (!per_dev->length) {
			per_dev->offset += si->cur_pg * PAGE_SIZE;
			/* If first stripe, Read in all read4write pages
			 * (if needed) before we calculate the first parity.
			 */
			if (do_xor)
				_read_4_write_first_stripe(ios);
		}
		if (!cur_len && do_xor)
			/* If last stripe r4w pages of last stripe */
			_read_4_write_last_stripe(ios);
		_read_4_write_execute(ios);

		for (i = 0; i < num_pages; i++) {
			pages[i] = _raid_page_alloc();
			if (unlikely(!pages[i]))
				return -ENOMEM;

			++(ios->cur_par_page);
		}

		BUG_ON(si->cur_comp < sp2d->data_devs);
		BUG_ON(si->cur_pg + num_pages > sp2d->pages_in_unit);

		ret = _ore_add_stripe_unit(ios,  &array_start, 0, pages,
					   per_dev, num_pages * PAGE_SIZE);
		if (unlikely(ret))
			return ret;

		if (do_xor) {
			_gen_xor_unit(sp2d);
			_sp2d_reset(sp2d, ios->r4w, ios->private);
		}
	}
	return 0;
}

int _ore_post_alloc_raid_stuff(struct ore_io_state *ios)
{
	if (ios->parity_pages) {
		struct ore_layout *layout = ios->layout;
		unsigned pages_in_unit = layout->stripe_unit / PAGE_SIZE;

		if (_sp2d_alloc(pages_in_unit, layout->group_width,
				layout->parity, &ios->sp2d)) {
			return -ENOMEM;
		}
	}
	return 0;
}

void _ore_free_raid_stuff(struct ore_io_state *ios)
{
	if (ios->sp2d) { /* writing and raid */
		unsigned i;

		for (i = 0; i < ios->cur_par_page; i++) {
			struct page *page = ios->parity_pages[i];

			if (page)
				_raid_page_free(page);
		}
		if (ios->extra_part_alloc)
			kfree(ios->parity_pages);
		/* If IO returned an error pages might need unlocking */
		_sp2d_reset(ios->sp2d, ios->r4w, ios->private);
		_sp2d_free(ios->sp2d);
	} else {
		/* Will only be set if raid reading && sglist is big */
		if (ios->extra_part_alloc)
			kfree(ios->per_dev[0].sglist);
	}
	if (ios->ios_read_4_write)
		ore_put_io_state(ios->ios_read_4_write);
}