ore_raid.c

   1 /*
   2  * Copyright (C) 2011
   3  * Boaz Harrosh <ooo@electrozaur.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 static struct page *_raid_page_alloc(void)
  25 {
  26         return alloc_page(GFP_KERNEL);
  27 }
  28
  29 static 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 = kcalloc(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         int p, c;
 148
 149         if (!sp2d->needed)
 150                 return;
 151
 152         for (c = data_devs - 1; c >= 0; --c)
 153                 for (p = sp2d->pages_in_unit - 1; p >= 0; --p) {
 154                         struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
 155
 156                         if (_1ps->page_is_read[c]) {
 157                                 struct page *page = _1ps->pages[c];
 158
 159                                 r4w->put_page(priv, page);
 160                                 _1ps->page_is_read[c] = false;
 161                         }
 162                 }
 163
 164         for (p = 0; p < sp2d->pages_in_unit; p++) {
 165                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
 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         int 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         unsigned tx_flags = ASYNC_TX_ACK;
 222
 223         if (sp2d->parity == 1)
 224                 tx_flags |= ASYNC_TX_XOR_ZERO_DST;
 225
 226         for (p = 0; p < sp2d->pages_in_unit; p++) {
 227                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
 228
 229                 if (!_1ps->write_count)
 230                         continue;
 231
 232                 init_async_submit(&_1ps->submit, tx_flags,
 233                         NULL, NULL, NULL, (addr_conv_t *)_1ps->scribble);
 234
 235                 if (sp2d->parity == 1)
 236                         _1ps->tx = async_xor(_1ps->pages[sp2d->data_devs],
 237                                                 _1ps->pages, 0, sp2d->data_devs,
 238                                                 PAGE_SIZE, &_1ps->submit);
 239                 else /* parity == 2 */
 240                         _1ps->tx = async_gen_syndrome(_1ps->pages, 0,
 241                                                 sp2d->data_devs + sp2d->parity,
 242                                                 PAGE_SIZE, &_1ps->submit);
 243         }
 244
 245         for (p = 0; p < sp2d->pages_in_unit; p++) {
 246                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
 247                 /* NOTE: We wait for HW synchronously (I don't have such HW
 248                  * to test with.) Is parallelism needed with today's multi
 249                  * cores?
 250                  */
 251                 async_tx_issue_pending(_1ps->tx);
 252         }
 253 }
 254
 255 void _ore_add_stripe_page(struct __stripe_pages_2d *sp2d,
 256                        struct ore_striping_info *si, struct page *page)
 257 {
 258         struct __1_page_stripe *_1ps;
 259
 260         sp2d->needed = true;
 261
 262         _1ps = &sp2d->_1p_stripes[si->cur_pg];
 263         _1ps->pages[si->cur_comp] = page;
 264         ++_1ps->write_count;
 265
 266         si->cur_pg = (si->cur_pg + 1) % sp2d->pages_in_unit;
 267         /* si->cur_comp is advanced outside at main loop */
 268 }
 269
 270 void _ore_add_sg_seg(struct ore_per_dev_state *per_dev, unsigned cur_len,
 271                      bool not_last)
 272 {
 273         struct osd_sg_entry *sge;
 274
 275         ORE_DBGMSG("dev=%d cur_len=0x%x not_last=%d cur_sg=%d "
 276                      "offset=0x%llx length=0x%x last_sgs_total=0x%x\n",
 277                      per_dev->dev, cur_len, not_last, per_dev->cur_sg,
 278                      _LLU(per_dev->offset), per_dev->length,
 279                      per_dev->last_sgs_total);
 280
 281         if (!per_dev->cur_sg) {
 282                 sge = per_dev->sglist;
 283
 284                 /* First time we prepare two entries */
 285                 if (per_dev->length) {
 286                         ++per_dev->cur_sg;
 287                         sge->offset = per_dev->offset;
 288                         sge->len = per_dev->length;
 289                 } else {
 290                         /* Here the parity is the first unit of this object.
 291                          * This happens every time we reach a parity device on
 292                          * the same stripe as the per_dev->offset. We need to
 293                          * just skip this unit.
 294                          */
 295                         per_dev->offset += cur_len;
 296                         return;
 297                 }
 298         } else {
 299                 /* finalize the last one */
 300                 sge = &per_dev->sglist[per_dev->cur_sg - 1];
 301                 sge->len = per_dev->length - per_dev->last_sgs_total;
 302         }
 303
 304         if (not_last) {
 305                 /* Partly prepare the next one */
 306                 struct osd_sg_entry *next_sge = sge + 1;
 307
 308                 ++per_dev->cur_sg;
 309                 next_sge->offset = sge->offset + sge->len + cur_len;
 310                 /* Save cur len so we know how mutch was added next time */
 311                 per_dev->last_sgs_total = per_dev->length;
 312                 next_sge->len = 0;
 313         } else if (!sge->len) {
 314                 /* Optimize for when the last unit is a parity */
 315                 --per_dev->cur_sg;
 316         }
 317 }
 318
 319 static int _alloc_read_4_write(struct ore_io_state *ios)
 320 {
 321         struct ore_layout *layout = ios->layout;
 322         int ret;
 323         /* We want to only read those pages not in cache so worst case
 324          * is a stripe populated with every other page
 325          */
 326         unsigned sgs_per_dev = ios->sp2d->pages_in_unit + 2;
 327
 328         ret = _ore_get_io_state(layout, ios->oc,
 329                                 layout->group_width * layout->mirrors_p1,
 330                                 sgs_per_dev, 0, &ios->ios_read_4_write);
 331         return ret;
 332 }
 333
 334 /* @si contains info of the to-be-inserted page. Update of @si should be
 335  * maintained by caller. Specificaly si->dev, si->obj_offset, ...
 336  */
 337 static int _add_to_r4w(struct ore_io_state *ios, struct ore_striping_info *si,
 338                        struct page *page, unsigned pg_len)
 339 {
 340         struct request_queue *q;
 341         struct ore_per_dev_state *per_dev;
 342         struct ore_io_state *read_ios;
 343         unsigned first_dev = si->dev - (si->dev %
 344                           (ios->layout->group_width * ios->layout->mirrors_p1));
 345         unsigned comp = si->dev - first_dev;
 346         unsigned added_len;
 347
 348         if (!ios->ios_read_4_write) {
 349                 int ret = _alloc_read_4_write(ios);
 350
 351                 if (unlikely(ret))
 352                         return ret;
 353         }
 354
 355         read_ios = ios->ios_read_4_write;
 356         read_ios->numdevs = ios->layout->group_width * ios->layout->mirrors_p1;
 357
 358         per_dev = &read_ios->per_dev[comp];
 359         if (!per_dev->length) {
 360                 per_dev->bio = bio_kmalloc(GFP_KERNEL,
 361                                            ios->sp2d->pages_in_unit);
 362                 if (unlikely(!per_dev->bio)) {
 363                         ORE_DBGMSG("Failed to allocate BIO size=%u\n",
 364                                      ios->sp2d->pages_in_unit);
 365                         return -ENOMEM;
 366                 }
 367                 per_dev->offset = si->obj_offset;
 368                 per_dev->dev = si->dev;
 369         } else if (si->obj_offset != (per_dev->offset + per_dev->length)) {
 370                 u64 gap = si->obj_offset - (per_dev->offset + per_dev->length);
 371
 372                 _ore_add_sg_seg(per_dev, gap, true);
 373         }
 374         q = osd_request_queue(ore_comp_dev(read_ios->oc, per_dev->dev));
 375         added_len = bio_add_pc_page(q, per_dev->bio, page, pg_len,
 376                                     si->obj_offset % PAGE_SIZE);
 377         if (unlikely(added_len != pg_len)) {
 378                 ORE_DBGMSG("Failed to bio_add_pc_page bi_vcnt=%d\n",
 379                               per_dev->bio->bi_vcnt);
 380                 return -ENOMEM;
 381         }
 382
 383         per_dev->length += pg_len;
 384         return 0;
 385 }
 386
 387 /* read the beginning of an unaligned first page */
 388 static int _add_to_r4w_first_page(struct ore_io_state *ios, struct page *page)
 389 {
 390         struct ore_striping_info si;
 391         unsigned pg_len;
 392
 393         ore_calc_stripe_info(ios->layout, ios->offset, 0, &si);
 394
 395         pg_len = si.obj_offset % PAGE_SIZE;
 396         si.obj_offset -= pg_len;
 397
 398         ORE_DBGMSG("offset=0x%llx len=0x%x index=0x%lx dev=%x\n",
 399                    _LLU(si.obj_offset), pg_len, page->index, si.dev);
 400
 401         return _add_to_r4w(ios, &si, page, pg_len);
 402 }
 403
 404 /* read the end of an incomplete last page */
 405 static int _add_to_r4w_last_page(struct ore_io_state *ios, u64 *offset)
 406 {
 407         struct ore_striping_info si;
 408         struct page *page;
 409         unsigned pg_len, p, c;
 410
 411         ore_calc_stripe_info(ios->layout, *offset, 0, &si);
 412
 413         p = si.cur_pg;
 414         c = si.cur_comp;
 415         page = ios->sp2d->_1p_stripes[p].pages[c];
 416
 417         pg_len = PAGE_SIZE - (si.unit_off % PAGE_SIZE);
 418         *offset += pg_len;
 419
 420         ORE_DBGMSG("p=%d, c=%d next-offset=0x%llx len=0x%x dev=%x par_dev=%d\n",
 421                    p, c, _LLU(*offset), pg_len, si.dev, si.par_dev);
 422
 423         BUG_ON(!page);
 424
 425         return _add_to_r4w(ios, &si, page, pg_len);
 426 }
 427
 428 static void _mark_read4write_pages_uptodate(struct ore_io_state *ios, int ret)
 429 {
 430         struct bio_vec *bv;
 431         unsigned i, d;
 432
 433         /* loop on all devices all pages */
 434         for (d = 0; d < ios->numdevs; d++) {
 435                 struct bio *bio = ios->per_dev[d].bio;
 436
 437                 if (!bio)
 438                         continue;
 439
 440                 bio_for_each_segment_all(bv, bio, i) {
 441                         struct page *page = bv->bv_page;
 442
 443                         SetPageUptodate(page);
 444                         if (PageError(page))
 445                                 ClearPageError(page);
 446                 }
 447         }
 448 }
 449
 450 /* read_4_write is hacked to read the start of the first stripe and/or
 451  * the end of the last stripe. If needed, with an sg-gap at each device/page.
 452  * It is assumed to be called after the to_be_written pages of the first stripe
 453  * are populating ios->sp2d[][]
 454  *
 455  * NOTE: We call ios->r4w->lock_fn for all pages needed for parity calculations
 456  * These pages are held at sp2d[p].pages[c] but with
 457  * sp2d[p].page_is_read[c] = true. At _sp2d_reset these pages are
 458  * ios->r4w->lock_fn(). The ios->r4w->lock_fn might signal that the page is
 459  * @uptodate=true, so we don't need to read it, only unlock, after IO.
 460  *
 461  * TODO: The read_4_write should calc a need_to_read_pages_count, if bigger then
 462  * to-be-written count, we should consider the xor-in-place mode.
 463  * need_to_read_pages_count is the actual number of pages not present in cache.
 464  * maybe "devs_in_group - ios->sp2d[p].write_count" is a good enough
 465  * approximation? In this mode the read pages are put in the empty places of
 466  * ios->sp2d[p][*], xor is calculated the same way. These pages are
 467  * allocated/freed and don't go through cache
 468  */
 469 static int _read_4_write_first_stripe(struct ore_io_state *ios)
 470 {
 471         struct ore_striping_info read_si;
 472         struct __stripe_pages_2d *sp2d = ios->sp2d;
 473         u64 offset = ios->si.first_stripe_start;
 474         unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;
 475
 476         if (offset == ios->offset) /* Go to start collect $200 */
 477                 goto read_last_stripe;
 478
 479         min_p = _sp2d_min_pg(sp2d);
 480         max_p = _sp2d_max_pg(sp2d);
 481
 482         ORE_DBGMSG("stripe_start=0x%llx ios->offset=0x%llx min_p=%d max_p=%d\n",
 483                    offset, ios->offset, min_p, max_p);
 484
 485         for (c = 0; ; c++) {
 486                 ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
 487                 read_si.obj_offset += min_p * PAGE_SIZE;
 488                 offset += min_p * PAGE_SIZE;
 489                 for (p = min_p; p <= max_p; p++) {
 490                         struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
 491                         struct page **pp = &_1ps->pages[c];
 492                         bool uptodate;
 493
 494                         if (*pp) {
 495                                 if (ios->offset % PAGE_SIZE)
 496                                         /* Read the remainder of the page */
 497                                         _add_to_r4w_first_page(ios, *pp);
 498                                 /* to-be-written pages start here */
 499                                 goto read_last_stripe;
 500                         }
 501
 502                         *pp = ios->r4w->get_page(ios->private, offset,
 503                                                  &uptodate);
 504                         if (unlikely(!*pp))
 505                                 return -ENOMEM;
 506
 507                         if (!uptodate)
 508                                 _add_to_r4w(ios, &read_si, *pp, PAGE_SIZE);
 509
 510                         /* Mark read-pages to be cache_released */
 511                         _1ps->page_is_read[c] = true;
 512                         read_si.obj_offset += PAGE_SIZE;
 513                         offset += PAGE_SIZE;
 514                 }
 515                 offset += (sp2d->pages_in_unit - p) * PAGE_SIZE;
 516         }
 517
 518 read_last_stripe:
 519         return 0;
 520 }
 521
 522 static int _read_4_write_last_stripe(struct ore_io_state *ios)
 523 {
 524         struct ore_striping_info read_si;
 525         struct __stripe_pages_2d *sp2d = ios->sp2d;
 526         u64 offset;
 527         u64 last_stripe_end;
 528         unsigned bytes_in_stripe = ios->si.bytes_in_stripe;
 529         unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;
 530
 531         offset = ios->offset + ios->length;
 532         if (offset % PAGE_SIZE)
 533                 _add_to_r4w_last_page(ios, &offset);
 534                 /* offset will be aligned to next page */
 535
 536         last_stripe_end = div_u64(offset + bytes_in_stripe - 1, bytes_in_stripe)
 537                                  * bytes_in_stripe;
 538         if (offset == last_stripe_end) /* Optimize for the aligned case */
 539                 goto read_it;
 540
 541         ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
 542         p = read_si.cur_pg;
 543         c = read_si.cur_comp;
 544
 545         if (min_p == sp2d->pages_in_unit) {
 546                 /* Didn't do it yet */
 547                 min_p = _sp2d_min_pg(sp2d);
 548                 max_p = _sp2d_max_pg(sp2d);
 549         }
 550
 551         ORE_DBGMSG("offset=0x%llx stripe_end=0x%llx min_p=%d max_p=%d\n",
 552                    offset, last_stripe_end, min_p, max_p);
 553
 554         while (offset < last_stripe_end) {
 555                 struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
 556
 557                 if ((min_p <= p) && (p <= max_p)) {
 558                         struct page *page;
 559                         bool uptodate;
 560
 561                         BUG_ON(_1ps->pages[c]);
 562                         page = ios->r4w->get_page(ios->private, offset,
 563                                                   &uptodate);
 564                         if (unlikely(!page))
 565                                 return -ENOMEM;
 566
 567                         _1ps->pages[c] = page;
 568                         /* Mark read-pages to be cache_released */
 569                         _1ps->page_is_read[c] = true;
 570                         if (!uptodate)
 571                                 _add_to_r4w(ios, &read_si, page, PAGE_SIZE);
 572                 }
 573
 574                 offset += PAGE_SIZE;
 575                 if (p == (sp2d->pages_in_unit - 1)) {
 576                         ++c;
 577                         p = 0;
 578                         ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
 579                 } else {
 580                         read_si.obj_offset += PAGE_SIZE;
 581                         ++p;
 582                 }
 583         }
 584
 585 read_it:
 586         return 0;
 587 }
 588
 589 static int _read_4_write_execute(struct ore_io_state *ios)
 590 {
 591         struct ore_io_state *ios_read;
 592         unsigned i;
 593         int ret;
 594
 595         ios_read = ios->ios_read_4_write;
 596         if (!ios_read)
 597                 return 0;
 598
 599         /* FIXME: Ugly to signal _sbi_read_mirror that we have bio(s). Change
 600          * to check for per_dev->bio
 601          */
 602         ios_read->pages = ios->pages;
 603
 604         /* Now read these devices */
 605         for (i = 0; i < ios_read->numdevs; i += ios_read->layout->mirrors_p1) {
 606                 ret = _ore_read_mirror(ios_read, i);
 607                 if (unlikely(ret))
 608                         return ret;
 609         }
 610
 611         ret = ore_io_execute(ios_read); /* Synchronus execution */
 612         if (unlikely(ret)) {
 613                 ORE_DBGMSG("!! ore_io_execute => %d\n", ret);
 614                 return ret;
 615         }
 616
 617         _mark_read4write_pages_uptodate(ios_read, ret);
 618         ore_put_io_state(ios_read);
 619         ios->ios_read_4_write = NULL; /* Might need a reuse at last stripe */
 620         return 0;
 621 }
 622
 623 /* In writes @cur_len means length left. .i.e cur_len==0 is the last parity U */
 624 int _ore_add_parity_unit(struct ore_io_state *ios,
 625                             struct ore_striping_info *si,
 626                             struct ore_per_dev_state *per_dev,
 627                             unsigned cur_len, bool do_xor)
 628 {
 629         if (ios->reading) {
 630                 if (per_dev->cur_sg >= ios->sgs_per_dev) {
 631                         ORE_DBGMSG("cur_sg(%d) >= sgs_per_dev(%d)\n" ,
 632                                 per_dev->cur_sg, ios->sgs_per_dev);
 633                         return -ENOMEM;
 634                 }
 635                 _ore_add_sg_seg(per_dev, cur_len, true);
 636         } else {
 637                 struct __stripe_pages_2d *sp2d = ios->sp2d;
 638                 struct page **pages = ios->parity_pages + ios->cur_par_page;
 639                 unsigned num_pages;
 640                 unsigned array_start = 0;
 641                 unsigned i;
 642                 int ret;
 643
 644                 si->cur_pg = _sp2d_min_pg(sp2d);
 645                 num_pages  = _sp2d_max_pg(sp2d) + 1 - si->cur_pg;
 646
 647                 if (!per_dev->length) {
 648                         per_dev->offset += si->cur_pg * PAGE_SIZE;
 649                         /* If first stripe, Read in all read4write pages
 650                          * (if needed) before we calculate the first parity.
 651                          */
 652                         if (do_xor)
 653                                 _read_4_write_first_stripe(ios);
 654                 }
 655                 if (!cur_len && do_xor)
 656                         /* If last stripe r4w pages of last stripe */
 657                         _read_4_write_last_stripe(ios);
 658                 _read_4_write_execute(ios);
 659
 660                 for (i = 0; i < num_pages; i++) {
 661                         pages[i] = _raid_page_alloc();
 662                         if (unlikely(!pages[i]))
 663                                 return -ENOMEM;
 664
 665                         ++(ios->cur_par_page);
 666                 }
 667
 668                 BUG_ON(si->cur_comp < sp2d->data_devs);
 669                 BUG_ON(si->cur_pg + num_pages > sp2d->pages_in_unit);
 670
 671                 ret = _ore_add_stripe_unit(ios,  &array_start, 0, pages,
 672                                            per_dev, num_pages * PAGE_SIZE);
 673                 if (unlikely(ret))
 674                         return ret;
 675
 676                 if (do_xor) {
 677                         _gen_xor_unit(sp2d);
 678                         _sp2d_reset(sp2d, ios->r4w, ios->private);
 679                 }
 680         }
 681         return 0;
 682 }
 683
 684 int _ore_post_alloc_raid_stuff(struct ore_io_state *ios)
 685 {
 686         if (ios->parity_pages) {
 687                 struct ore_layout *layout = ios->layout;
 688                 unsigned pages_in_unit = layout->stripe_unit / PAGE_SIZE;
 689
 690                 if (_sp2d_alloc(pages_in_unit, layout->group_width,
 691                                 layout->parity, &ios->sp2d)) {
 692                         return -ENOMEM;
 693                 }
 694         }
 695         return 0;
 696 }
 697
 698 void _ore_free_raid_stuff(struct ore_io_state *ios)
 699 {
 700         if (ios->sp2d) { /* writing and raid */
 701                 unsigned i;
 702
 703                 for (i = 0; i < ios->cur_par_page; i++) {
 704                         struct page *page = ios->parity_pages[i];
 705
 706                         if (page)
 707                                 _raid_page_free(page);
 708                 }
 709                 if (ios->extra_part_alloc)
 710                         kfree(ios->parity_pages);
 711                 /* If IO returned an error pages might need unlocking */
 712                 _sp2d_reset(ios->sp2d, ios->r4w, ios->private);
 713                 _sp2d_free(ios->sp2d);
 714         } else {
 715                 /* Will only be set if raid reading && sglist is big */
 716                 if (ios->extra_part_alloc)
 717                         kfree(ios->per_dev[0].sglist);
 718         }
 719         if (ios->ios_read_4_write)
 720                 ore_put_io_state(ios->ios_read_4_write);
 721 }