Merge commit 'v3.4.9' into android-t114-3.4
[linux-2.6.git] / fs / exofs / ore_raid.c
1 /*
2  * Copyright (C) 2011
3  * Boaz Harrosh <bharrosh@panasas.com>
4  *
5  * This file is part of the objects raid engine (ore).
6  *
7  * It is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as published
9  * by the Free Software Foundation.
10  *
11  * You should have received a copy of the GNU General Public License
12  * along with "ore". If not, write to the Free Software Foundation, Inc:
13  *      "Free Software Foundation <info@fsf.org>"
14  */
15
16 #include <linux/gfp.h>
17 #include <linux/async_tx.h>
18
19 #include "ore_raid.h"
20
21 #undef ORE_DBGMSG2
22 #define ORE_DBGMSG2 ORE_DBGMSG
23
24 struct page *_raid_page_alloc(void)
25 {
26         return alloc_page(GFP_KERNEL);
27 }
28
29 void _raid_page_free(struct page *p)
30 {
31         __free_page(p);
32 }
33
34 /* This struct is forward declare in ore_io_state, but is private to here.
35  * It is put on ios->sp2d for RAID5/6 writes only. See _gen_xor_unit.
36  *
37  * __stripe_pages_2d is a 2d array of pages, and it is also a corner turn.
38  * Ascending page index access is sp2d(p-minor, c-major). But storage is
39  * sp2d[p-minor][c-major], so it can be properlly presented to the async-xor
40  * API.
41  */
42 struct __stripe_pages_2d {
43         /* Cache some hot path repeated calculations */
44         unsigned parity;
45         unsigned data_devs;
46         unsigned pages_in_unit;
47
48         bool needed ;
49
50         /* Array size is pages_in_unit (layout->stripe_unit / PAGE_SIZE) */
51         struct __1_page_stripe {
52                 bool alloc;
53                 unsigned write_count;
54                 struct async_submit_ctl submit;
55                 struct dma_async_tx_descriptor *tx;
56
57                 /* The size of this array is data_devs + parity */
58                 struct page **pages;
59                 struct page **scribble;
60                 /* bool array, size of this array is data_devs */
61                 char *page_is_read;
62         } _1p_stripes[];
63 };
64
65 /* This can get bigger then a page. So support multiple page allocations
66  * _sp2d_free should be called even if _sp2d_alloc fails (by returning
67  * none-zero).
68  */
69 static int _sp2d_alloc(unsigned pages_in_unit, unsigned group_width,
70                        unsigned parity, struct __stripe_pages_2d **psp2d)
71 {
72         struct __stripe_pages_2d *sp2d;
73         unsigned data_devs = group_width - parity;
74         struct _alloc_all_bytes {
75                 struct __alloc_stripe_pages_2d {
76                         struct __stripe_pages_2d sp2d;
77                         struct __1_page_stripe _1p_stripes[pages_in_unit];
78                 } __asp2d;
79                 struct __alloc_1p_arrays {
80                         struct page *pages[group_width];
81                         struct page *scribble[group_width];
82                         char page_is_read[data_devs];
83                 } __a1pa[pages_in_unit];
84         } *_aab;
85         struct __alloc_1p_arrays *__a1pa;
86         struct __alloc_1p_arrays *__a1pa_end;
87         const unsigned sizeof__a1pa = sizeof(_aab->__a1pa[0]);
88         unsigned num_a1pa, alloc_size, i;
89
90         /* FIXME: check these numbers in ore_verify_layout */
91         BUG_ON(sizeof(_aab->__asp2d) > PAGE_SIZE);
92         BUG_ON(sizeof__a1pa > PAGE_SIZE);
93
94         if (sizeof(*_aab) > PAGE_SIZE) {
95                 num_a1pa = (PAGE_SIZE - sizeof(_aab->__asp2d)) / sizeof__a1pa;
96                 alloc_size = sizeof(_aab->__asp2d) + sizeof__a1pa * num_a1pa;
97         } else {
98                 num_a1pa = pages_in_unit;
99                 alloc_size = sizeof(*_aab);
100         }
101
102         _aab = kzalloc(alloc_size, GFP_KERNEL);
103         if (unlikely(!_aab)) {
104                 ORE_DBGMSG("!! Failed to alloc sp2d size=%d\n", alloc_size);
105                 return -ENOMEM;
106         }
107
108         sp2d = &_aab->__asp2d.sp2d;
109         *psp2d = sp2d; /* From here Just call _sp2d_free */
110
111         __a1pa = _aab->__a1pa;
112         __a1pa_end = __a1pa + num_a1pa;
113
114         for (i = 0; i < pages_in_unit; ++i) {
115                 if (unlikely(__a1pa >= __a1pa_end)) {
116                         num_a1pa = min_t(unsigned, PAGE_SIZE / sizeof__a1pa,
117                                                         pages_in_unit - i);
118
119                         __a1pa = kzalloc(num_a1pa * sizeof__a1pa, GFP_KERNEL);
120                         if (unlikely(!__a1pa)) {
121                                 ORE_DBGMSG("!! Failed to _alloc_1p_arrays=%d\n",
122                                            num_a1pa);
123                                 return -ENOMEM;
124                         }
125                         __a1pa_end = __a1pa + num_a1pa;
126                         /* First *pages is marked for kfree of the buffer */
127                         sp2d->_1p_stripes[i].alloc = true;
128                 }
129
130                 sp2d->_1p_stripes[i].pages = __a1pa->pages;
131                 sp2d->_1p_stripes[i].scribble = __a1pa->scribble ;
132                 sp2d->_1p_stripes[i].page_is_read = __a1pa->page_is_read;
133                 ++__a1pa;
134         }
135
136         sp2d->parity = parity;
137         sp2d->data_devs = data_devs;
138         sp2d->pages_in_unit = pages_in_unit;
139         return 0;
140 }
141
142 static void _sp2d_reset(struct __stripe_pages_2d *sp2d,
143                         const struct _ore_r4w_op *r4w, void *priv)
144 {
145         unsigned data_devs = sp2d->data_devs;
146         unsigned group_width = data_devs + sp2d->parity;
147         unsigned p;
148
149         if (!sp2d->needed)
150                 return;
151
152         for (p = 0; p < sp2d->pages_in_unit; p++) {
153                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
154
155                 if (_1ps->write_count < group_width) {
156                         unsigned c;
157
158                         for (c = 0; c < data_devs; c++)
159                                 if (_1ps->page_is_read[c]) {
160                                         struct page *page = _1ps->pages[c];
161
162                                         r4w->put_page(priv, page);
163                                         _1ps->page_is_read[c] = false;
164                                 }
165                 }
166
167                 memset(_1ps->pages, 0, group_width * sizeof(*_1ps->pages));
168                 _1ps->write_count = 0;
169                 _1ps->tx = NULL;
170         }
171
172         sp2d->needed = false;
173 }
174
175 static void _sp2d_free(struct __stripe_pages_2d *sp2d)
176 {
177         unsigned i;
178
179         if (!sp2d)
180                 return;
181
182         for (i = 0; i < sp2d->pages_in_unit; ++i) {
183                 if (sp2d->_1p_stripes[i].alloc)
184                         kfree(sp2d->_1p_stripes[i].pages);
185         }
186
187         kfree(sp2d);
188 }
189
190 static unsigned _sp2d_min_pg(struct __stripe_pages_2d *sp2d)
191 {
192         unsigned p;
193
194         for (p = 0; p < sp2d->pages_in_unit; p++) {
195                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
196
197                 if (_1ps->write_count)
198                         return p;
199         }
200
201         return ~0;
202 }
203
204 static unsigned _sp2d_max_pg(struct __stripe_pages_2d *sp2d)
205 {
206         unsigned p;
207
208         for (p = sp2d->pages_in_unit - 1; p >= 0; --p) {
209                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
210
211                 if (_1ps->write_count)
212                         return p;
213         }
214
215         return ~0;
216 }
217
218 static void _gen_xor_unit(struct __stripe_pages_2d *sp2d)
219 {
220         unsigned p;
221         for (p = 0; p < sp2d->pages_in_unit; p++) {
222                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
223
224                 if (!_1ps->write_count)
225                         continue;
226
227                 init_async_submit(&_1ps->submit,
228                         ASYNC_TX_XOR_ZERO_DST | ASYNC_TX_ACK,
229                         NULL,
230                         NULL, NULL,
231                         (addr_conv_t *)_1ps->scribble);
232
233                 /* TODO: raid6 */
234                 _1ps->tx = async_xor(_1ps->pages[sp2d->data_devs], _1ps->pages,
235                                      0, sp2d->data_devs, PAGE_SIZE,
236                                      &_1ps->submit);
237         }
238
239         for (p = 0; p < sp2d->pages_in_unit; p++) {
240                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
241                 /* NOTE: We wait for HW synchronously (I don't have such HW
242                  * to test with.) Is parallelism needed with today's multi
243                  * cores?
244                  */
245                 async_tx_issue_pending(_1ps->tx);
246         }
247 }
248
249 void _ore_add_stripe_page(struct __stripe_pages_2d *sp2d,
250                        struct ore_striping_info *si, struct page *page)
251 {
252         struct __1_page_stripe *_1ps;
253
254         sp2d->needed = true;
255
256         _1ps = &sp2d->_1p_stripes[si->cur_pg];
257         _1ps->pages[si->cur_comp] = page;
258         ++_1ps->write_count;
259
260         si->cur_pg = (si->cur_pg + 1) % sp2d->pages_in_unit;
261         /* si->cur_comp is advanced outside at main loop */
262 }
263
264 void _ore_add_sg_seg(struct ore_per_dev_state *per_dev, unsigned cur_len,
265                      bool not_last)
266 {
267         struct osd_sg_entry *sge;
268
269         ORE_DBGMSG("dev=%d cur_len=0x%x not_last=%d cur_sg=%d "
270                      "offset=0x%llx length=0x%x last_sgs_total=0x%x\n",
271                      per_dev->dev, cur_len, not_last, per_dev->cur_sg,
272                      _LLU(per_dev->offset), per_dev->length,
273                      per_dev->last_sgs_total);
274
275         if (!per_dev->cur_sg) {
276                 sge = per_dev->sglist;
277
278                 /* First time we prepare two entries */
279                 if (per_dev->length) {
280                         ++per_dev->cur_sg;
281                         sge->offset = per_dev->offset;
282                         sge->len = per_dev->length;
283                 } else {
284                         /* Here the parity is the first unit of this object.
285                          * This happens every time we reach a parity device on
286                          * the same stripe as the per_dev->offset. We need to
287                          * just skip this unit.
288                          */
289                         per_dev->offset += cur_len;
290                         return;
291                 }
292         } else {
293                 /* finalize the last one */
294                 sge = &per_dev->sglist[per_dev->cur_sg - 1];
295                 sge->len = per_dev->length - per_dev->last_sgs_total;
296         }
297
298         if (not_last) {
299                 /* Partly prepare the next one */
300                 struct osd_sg_entry *next_sge = sge + 1;
301
302                 ++per_dev->cur_sg;
303                 next_sge->offset = sge->offset + sge->len + cur_len;
304                 /* Save cur len so we know how mutch was added next time */
305                 per_dev->last_sgs_total = per_dev->length;
306                 next_sge->len = 0;
307         } else if (!sge->len) {
308                 /* Optimize for when the last unit is a parity */
309                 --per_dev->cur_sg;
310         }
311 }
312
313 static int _alloc_read_4_write(struct ore_io_state *ios)
314 {
315         struct ore_layout *layout = ios->layout;
316         int ret;
317         /* We want to only read those pages not in cache so worst case
318          * is a stripe populated with every other page
319          */
320         unsigned sgs_per_dev = ios->sp2d->pages_in_unit + 2;
321
322         ret = _ore_get_io_state(layout, ios->oc,
323                                 layout->group_width * layout->mirrors_p1,
324                                 sgs_per_dev, 0, &ios->ios_read_4_write);
325         return ret;
326 }
327
328 /* @si contains info of the to-be-inserted page. Update of @si should be
329  * maintained by caller. Specificaly si->dev, si->obj_offset, ...
330  */
331 static int _add_to_r4w(struct ore_io_state *ios, struct ore_striping_info *si,
332                        struct page *page, unsigned pg_len)
333 {
334         struct request_queue *q;
335         struct ore_per_dev_state *per_dev;
336         struct ore_io_state *read_ios;
337         unsigned first_dev = si->dev - (si->dev %
338                           (ios->layout->group_width * ios->layout->mirrors_p1));
339         unsigned comp = si->dev - first_dev;
340         unsigned added_len;
341
342         if (!ios->ios_read_4_write) {
343                 int ret = _alloc_read_4_write(ios);
344
345                 if (unlikely(ret))
346                         return ret;
347         }
348
349         read_ios = ios->ios_read_4_write;
350         read_ios->numdevs = ios->layout->group_width * ios->layout->mirrors_p1;
351
352         per_dev = &read_ios->per_dev[comp];
353         if (!per_dev->length) {
354                 per_dev->bio = bio_kmalloc(GFP_KERNEL,
355                                            ios->sp2d->pages_in_unit);
356                 if (unlikely(!per_dev->bio)) {
357                         ORE_DBGMSG("Failed to allocate BIO size=%u\n",
358                                      ios->sp2d->pages_in_unit);
359                         return -ENOMEM;
360                 }
361                 per_dev->offset = si->obj_offset;
362                 per_dev->dev = si->dev;
363         } else if (si->obj_offset != (per_dev->offset + per_dev->length)) {
364                 u64 gap = si->obj_offset - (per_dev->offset + per_dev->length);
365
366                 _ore_add_sg_seg(per_dev, gap, true);
367         }
368         q = osd_request_queue(ore_comp_dev(read_ios->oc, per_dev->dev));
369         added_len = bio_add_pc_page(q, per_dev->bio, page, pg_len,
370                                     si->obj_offset % PAGE_SIZE);
371         if (unlikely(added_len != pg_len)) {
372                 ORE_DBGMSG("Failed to bio_add_pc_page bi_vcnt=%d\n",
373                               per_dev->bio->bi_vcnt);
374                 return -ENOMEM;
375         }
376
377         per_dev->length += pg_len;
378         return 0;
379 }
380
381 /* read the beginning of an unaligned first page */
382 static int _add_to_r4w_first_page(struct ore_io_state *ios, struct page *page)
383 {
384         struct ore_striping_info si;
385         unsigned pg_len;
386
387         ore_calc_stripe_info(ios->layout, ios->offset, 0, &si);
388
389         pg_len = si.obj_offset % PAGE_SIZE;
390         si.obj_offset -= pg_len;
391
392         ORE_DBGMSG("offset=0x%llx len=0x%x index=0x%lx dev=%x\n",
393                    _LLU(si.obj_offset), pg_len, page->index, si.dev);
394
395         return _add_to_r4w(ios, &si, page, pg_len);
396 }
397
398 /* read the end of an incomplete last page */
399 static int _add_to_r4w_last_page(struct ore_io_state *ios, u64 *offset)
400 {
401         struct ore_striping_info si;
402         struct page *page;
403         unsigned pg_len, p, c;
404
405         ore_calc_stripe_info(ios->layout, *offset, 0, &si);
406
407         p = si.unit_off / PAGE_SIZE;
408         c = _dev_order(ios->layout->group_width * ios->layout->mirrors_p1,
409                        ios->layout->mirrors_p1, si.par_dev, si.dev);
410         page = ios->sp2d->_1p_stripes[p].pages[c];
411
412         pg_len = PAGE_SIZE - (si.unit_off % PAGE_SIZE);
413         *offset += pg_len;
414
415         ORE_DBGMSG("p=%d, c=%d next-offset=0x%llx len=0x%x dev=%x par_dev=%d\n",
416                    p, c, _LLU(*offset), pg_len, si.dev, si.par_dev);
417
418         BUG_ON(!page);
419
420         return _add_to_r4w(ios, &si, page, pg_len);
421 }
422
423 static void _mark_read4write_pages_uptodate(struct ore_io_state *ios, int ret)
424 {
425         struct bio_vec *bv;
426         unsigned i, d;
427
428         /* loop on all devices all pages */
429         for (d = 0; d < ios->numdevs; d++) {
430                 struct bio *bio = ios->per_dev[d].bio;
431
432                 if (!bio)
433                         continue;
434
435                 __bio_for_each_segment(bv, bio, i, 0) {
436                         struct page *page = bv->bv_page;
437
438                         SetPageUptodate(page);
439                         if (PageError(page))
440                                 ClearPageError(page);
441                 }
442         }
443 }
444
445 /* read_4_write is hacked to read the start of the first stripe and/or
446  * the end of the last stripe. If needed, with an sg-gap at each device/page.
447  * It is assumed to be called after the to_be_written pages of the first stripe
448  * are populating ios->sp2d[][]
449  *
450  * NOTE: We call ios->r4w->lock_fn for all pages needed for parity calculations
451  * These pages are held at sp2d[p].pages[c] but with
452  * sp2d[p].page_is_read[c] = true. At _sp2d_reset these pages are
453  * ios->r4w->lock_fn(). The ios->r4w->lock_fn might signal that the page is
454  * @uptodate=true, so we don't need to read it, only unlock, after IO.
455  *
456  * TODO: The read_4_write should calc a need_to_read_pages_count, if bigger then
457  * to-be-written count, we should consider the xor-in-place mode.
458  * need_to_read_pages_count is the actual number of pages not present in cache.
459  * maybe "devs_in_group - ios->sp2d[p].write_count" is a good enough
460  * approximation? In this mode the read pages are put in the empty places of
461  * ios->sp2d[p][*], xor is calculated the same way. These pages are
462  * allocated/freed and don't go through cache
463  */
464 static int _read_4_write_first_stripe(struct ore_io_state *ios)
465 {
466         struct ore_striping_info read_si;
467         struct __stripe_pages_2d *sp2d = ios->sp2d;
468         u64 offset = ios->si.first_stripe_start;
469         unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;
470
471         if (offset == ios->offset) /* Go to start collect $200 */
472                 goto read_last_stripe;
473
474         min_p = _sp2d_min_pg(sp2d);
475         max_p = _sp2d_max_pg(sp2d);
476
477         ORE_DBGMSG("stripe_start=0x%llx ios->offset=0x%llx min_p=%d max_p=%d\n",
478                    offset, ios->offset, min_p, max_p);
479
480         for (c = 0; ; c++) {
481                 ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
482                 read_si.obj_offset += min_p * PAGE_SIZE;
483                 offset += min_p * PAGE_SIZE;
484                 for (p = min_p; p <= max_p; p++) {
485                         struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
486                         struct page **pp = &_1ps->pages[c];
487                         bool uptodate;
488
489                         if (*pp) {
490                                 if (ios->offset % PAGE_SIZE)
491                                         /* Read the remainder of the page */
492                                         _add_to_r4w_first_page(ios, *pp);
493                                 /* to-be-written pages start here */
494                                 goto read_last_stripe;
495                         }
496
497                         *pp = ios->r4w->get_page(ios->private, offset,
498                                                  &uptodate);
499                         if (unlikely(!*pp))
500                                 return -ENOMEM;
501
502                         if (!uptodate)
503                                 _add_to_r4w(ios, &read_si, *pp, PAGE_SIZE);
504
505                         /* Mark read-pages to be cache_released */
506                         _1ps->page_is_read[c] = true;
507                         read_si.obj_offset += PAGE_SIZE;
508                         offset += PAGE_SIZE;
509                 }
510                 offset += (sp2d->pages_in_unit - p) * PAGE_SIZE;
511         }
512
513 read_last_stripe:
514         return 0;
515 }
516
517 static int _read_4_write_last_stripe(struct ore_io_state *ios)
518 {
519         struct ore_striping_info read_si;
520         struct __stripe_pages_2d *sp2d = ios->sp2d;
521         u64 offset;
522         u64 last_stripe_end;
523         unsigned bytes_in_stripe = ios->si.bytes_in_stripe;
524         unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;
525
526         offset = ios->offset + ios->length;
527         if (offset % PAGE_SIZE)
528                 _add_to_r4w_last_page(ios, &offset);
529                 /* offset will be aligned to next page */
530
531         last_stripe_end = div_u64(offset + bytes_in_stripe - 1, bytes_in_stripe)
532                                  * bytes_in_stripe;
533         if (offset == last_stripe_end) /* Optimize for the aligned case */
534                 goto read_it;
535
536         ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
537         p = read_si.unit_off / PAGE_SIZE;
538         c = _dev_order(ios->layout->group_width * ios->layout->mirrors_p1,
539                        ios->layout->mirrors_p1, read_si.par_dev, read_si.dev);
540
541         if (min_p == sp2d->pages_in_unit) {
542                 /* Didn't do it yet */
543                 min_p = _sp2d_min_pg(sp2d);
544                 max_p = _sp2d_max_pg(sp2d);
545         }
546
547         ORE_DBGMSG("offset=0x%llx stripe_end=0x%llx min_p=%d max_p=%d\n",
548                    offset, last_stripe_end, min_p, max_p);
549
550         while (offset < last_stripe_end) {
551                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
552
553                 if ((min_p <= p) && (p <= max_p)) {
554                         struct page *page;
555                         bool uptodate;
556
557                         BUG_ON(_1ps->pages[c]);
558                         page = ios->r4w->get_page(ios->private, offset,
559                                                   &uptodate);
560                         if (unlikely(!page))
561                                 return -ENOMEM;
562
563                         _1ps->pages[c] = page;
564                         /* Mark read-pages to be cache_released */
565                         _1ps->page_is_read[c] = true;
566                         if (!uptodate)
567                                 _add_to_r4w(ios, &read_si, page, PAGE_SIZE);
568                 }
569
570                 offset += PAGE_SIZE;
571                 if (p == (sp2d->pages_in_unit - 1)) {
572                         ++c;
573                         p = 0;
574                         ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
575                 } else {
576                         read_si.obj_offset += PAGE_SIZE;
577                         ++p;
578                 }
579         }
580
581 read_it:
582         return 0;
583 }
584
585 static int _read_4_write_execute(struct ore_io_state *ios)
586 {
587         struct ore_io_state *ios_read;
588         unsigned i;
589         int ret;
590
591         ios_read = ios->ios_read_4_write;
592         if (!ios_read)
593                 return 0;
594
595         /* FIXME: Ugly to signal _sbi_read_mirror that we have bio(s). Change
596          * to check for per_dev->bio
597          */
598         ios_read->pages = ios->pages;
599
600         /* Now read these devices */
601         for (i = 0; i < ios_read->numdevs; i += ios_read->layout->mirrors_p1) {
602                 ret = _ore_read_mirror(ios_read, i);
603                 if (unlikely(ret))
604                         return ret;
605         }
606
607         ret = ore_io_execute(ios_read); /* Synchronus execution */
608         if (unlikely(ret)) {
609                 ORE_DBGMSG("!! ore_io_execute => %d\n", ret);
610                 return ret;
611         }
612
613         _mark_read4write_pages_uptodate(ios_read, ret);
614         ore_put_io_state(ios_read);
615         ios->ios_read_4_write = NULL; /* Might need a reuse at last stripe */
616         return 0;
617 }
618
619 /* In writes @cur_len means length left. .i.e cur_len==0 is the last parity U */
620 int _ore_add_parity_unit(struct ore_io_state *ios,
621                             struct ore_striping_info *si,
622                             struct ore_per_dev_state *per_dev,
623                             unsigned cur_len)
624 {
625         if (ios->reading) {
626                 if (per_dev->cur_sg >= ios->sgs_per_dev) {
627                         ORE_DBGMSG("cur_sg(%d) >= sgs_per_dev(%d)\n" ,
628                                 per_dev->cur_sg, ios->sgs_per_dev);
629                         return -ENOMEM;
630                 }
631                 _ore_add_sg_seg(per_dev, cur_len, true);
632         } else {
633                 struct __stripe_pages_2d *sp2d = ios->sp2d;
634                 struct page **pages = ios->parity_pages + ios->cur_par_page;
635                 unsigned num_pages;
636                 unsigned array_start = 0;
637                 unsigned i;
638                 int ret;
639
640                 si->cur_pg = _sp2d_min_pg(sp2d);
641                 num_pages  = _sp2d_max_pg(sp2d) + 1 - si->cur_pg;
642
643                 if (!cur_len) /* If last stripe operate on parity comp */
644                         si->cur_comp = sp2d->data_devs;
645
646                 if (!per_dev->length) {
647                         per_dev->offset += si->cur_pg * PAGE_SIZE;
648                         /* If first stripe, Read in all read4write pages
649                          * (if needed) before we calculate the first parity.
650                          */
651                         _read_4_write_first_stripe(ios);
652                 }
653                 if (!cur_len) /* If last stripe r4w pages of last stripe */
654                         _read_4_write_last_stripe(ios);
655                 _read_4_write_execute(ios);
656
657                 for (i = 0; i < num_pages; i++) {
658                         pages[i] = _raid_page_alloc();
659                         if (unlikely(!pages[i]))
660                                 return -ENOMEM;
661
662                         ++(ios->cur_par_page);
663                 }
664
665                 BUG_ON(si->cur_comp != sp2d->data_devs);
666                 BUG_ON(si->cur_pg + num_pages > sp2d->pages_in_unit);
667
668                 ret = _ore_add_stripe_unit(ios,  &array_start, 0, pages,
669                                            per_dev, num_pages * PAGE_SIZE);
670                 if (unlikely(ret))
671                         return ret;
672
673                 /* TODO: raid6 if (last_parity_dev) */
674                 _gen_xor_unit(sp2d);
675                 _sp2d_reset(sp2d, ios->r4w, ios->private);
676         }
677         return 0;
678 }
679
680 int _ore_post_alloc_raid_stuff(struct ore_io_state *ios)
681 {
682         if (ios->parity_pages) {
683                 struct ore_layout *layout = ios->layout;
684                 unsigned pages_in_unit = layout->stripe_unit / PAGE_SIZE;
685
686                 if (_sp2d_alloc(pages_in_unit, layout->group_width,
687                                 layout->parity, &ios->sp2d)) {
688                         return -ENOMEM;
689                 }
690         }
691         return 0;
692 }
693
694 void _ore_free_raid_stuff(struct ore_io_state *ios)
695 {
696         if (ios->sp2d) { /* writing and raid */
697                 unsigned i;
698
699                 for (i = 0; i < ios->cur_par_page; i++) {
700                         struct page *page = ios->parity_pages[i];
701
702                         if (page)
703                                 _raid_page_free(page);
704                 }
705                 if (ios->extra_part_alloc)
706                         kfree(ios->parity_pages);
707                 /* If IO returned an error pages might need unlocking */
708                 _sp2d_reset(ios->sp2d, ios->r4w, ios->private);
709                 _sp2d_free(ios->sp2d);
710         } else {
711                 /* Will only be set if raid reading && sglist is big */
712                 if (ios->extra_part_alloc)
713                         kfree(ios->per_dev[0].sglist);
714         }
715         if (ios->ios_read_4_write)
716                 ore_put_io_state(ios->ios_read_4_write);
717 }