linux/drivers/md/raid5.c
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   1/*
   2 * raid5.c : Multiple Devices driver for Linux
   3 *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4 *         Copyright (C) 1999, 2000 Ingo Molnar
   5 *         Copyright (C) 2002, 2003 H. Peter Anvin
   6 *
   7 * RAID-4/5/6 management functions.
   8 * Thanks to Penguin Computing for making the RAID-6 development possible
   9 * by donating a test server!
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License as published by
  13 * the Free Software Foundation; either version 2, or (at your option)
  14 * any later version.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * (for example /usr/src/linux/COPYING); if not, write to the Free
  18 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21/*
  22 * BITMAP UNPLUGGING:
  23 *
  24 * The sequencing for updating the bitmap reliably is a little
  25 * subtle (and I got it wrong the first time) so it deserves some
  26 * explanation.
  27 *
  28 * We group bitmap updates into batches.  Each batch has a number.
  29 * We may write out several batches at once, but that isn't very important.
  30 * conf->seq_write is the number of the last batch successfully written.
  31 * conf->seq_flush is the number of the last batch that was closed to
  32 *    new additions.
  33 * When we discover that we will need to write to any block in a stripe
  34 * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35 * the number of the batch it will be in. This is seq_flush+1.
  36 * When we are ready to do a write, if that batch hasn't been written yet,
  37 *   we plug the array and queue the stripe for later.
  38 * When an unplug happens, we increment bm_flush, thus closing the current
  39 *   batch.
  40 * When we notice that bm_flush > bm_write, we write out all pending updates
  41 * to the bitmap, and advance bm_write to where bm_flush was.
  42 * This may occasionally write a bit out twice, but is sure never to
  43 * miss any bits.
  44 */
  45
  46#include <linux/blkdev.h>
  47#include <linux/kthread.h>
  48#include <linux/raid/pq.h>
  49#include <linux/async_tx.h>
  50#include <linux/module.h>
  51#include <linux/async.h>
  52#include <linux/seq_file.h>
  53#include <linux/cpu.h>
  54#include <linux/slab.h>
  55#include <linux/ratelimit.h>
  56#include <trace/events/block.h>
  57
  58#include "md.h"
  59#include "raid5.h"
  60#include "raid0.h"
  61#include "bitmap.h"
  62
  63/*
  64 * Stripe cache
  65 */
  66
  67#define NR_STRIPES              256
  68#define STRIPE_SIZE             PAGE_SIZE
  69#define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  70#define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  71#define IO_THRESHOLD            1
  72#define BYPASS_THRESHOLD        1
  73#define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  74#define HASH_MASK               (NR_HASH - 1)
  75
  76static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  77{
  78        int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  79        return &conf->stripe_hashtbl[hash];
  80}
  81
  82/* bio's attached to a stripe+device for I/O are linked together in bi_sector
  83 * order without overlap.  There may be several bio's per stripe+device, and
  84 * a bio could span several devices.
  85 * When walking this list for a particular stripe+device, we must never proceed
  86 * beyond a bio that extends past this device, as the next bio might no longer
  87 * be valid.
  88 * This function is used to determine the 'next' bio in the list, given the sector
  89 * of the current stripe+device
  90 */
  91static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
  92{
  93        int sectors = bio->bi_size >> 9;
  94        if (bio->bi_sector + sectors < sector + STRIPE_SECTORS)
  95                return bio->bi_next;
  96        else
  97                return NULL;
  98}
  99
 100/*
 101 * We maintain a biased count of active stripes in the bottom 16 bits of
 102 * bi_phys_segments, and a count of processed stripes in the upper 16 bits
 103 */
 104static inline int raid5_bi_processed_stripes(struct bio *bio)
 105{
 106        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 107        return (atomic_read(segments) >> 16) & 0xffff;
 108}
 109
 110static inline int raid5_dec_bi_active_stripes(struct bio *bio)
 111{
 112        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 113        return atomic_sub_return(1, segments) & 0xffff;
 114}
 115
 116static inline void raid5_inc_bi_active_stripes(struct bio *bio)
 117{
 118        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 119        atomic_inc(segments);
 120}
 121
 122static inline void raid5_set_bi_processed_stripes(struct bio *bio,
 123        unsigned int cnt)
 124{
 125        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 126        int old, new;
 127
 128        do {
 129                old = atomic_read(segments);
 130                new = (old & 0xffff) | (cnt << 16);
 131        } while (atomic_cmpxchg(segments, old, new) != old);
 132}
 133
 134static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
 135{
 136        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 137        atomic_set(segments, cnt);
 138}
 139
 140/* Find first data disk in a raid6 stripe */
 141static inline int raid6_d0(struct stripe_head *sh)
 142{
 143        if (sh->ddf_layout)
 144                /* ddf always start from first device */
 145                return 0;
 146        /* md starts just after Q block */
 147        if (sh->qd_idx == sh->disks - 1)
 148                return 0;
 149        else
 150                return sh->qd_idx + 1;
 151}
 152static inline int raid6_next_disk(int disk, int raid_disks)
 153{
 154        disk++;
 155        return (disk < raid_disks) ? disk : 0;
 156}
 157
 158/* When walking through the disks in a raid5, starting at raid6_d0,
 159 * We need to map each disk to a 'slot', where the data disks are slot
 160 * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 161 * is raid_disks-1.  This help does that mapping.
 162 */
 163static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 164                             int *count, int syndrome_disks)
 165{
 166        int slot = *count;
 167
 168        if (sh->ddf_layout)
 169                (*count)++;
 170        if (idx == sh->pd_idx)
 171                return syndrome_disks;
 172        if (idx == sh->qd_idx)
 173                return syndrome_disks + 1;
 174        if (!sh->ddf_layout)
 175                (*count)++;
 176        return slot;
 177}
 178
 179static void return_io(struct bio *return_bi)
 180{
 181        struct bio *bi = return_bi;
 182        while (bi) {
 183
 184                return_bi = bi->bi_next;
 185                bi->bi_next = NULL;
 186                bi->bi_size = 0;
 187                trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 188                                         bi, 0);
 189                bio_endio(bi, 0);
 190                bi = return_bi;
 191        }
 192}
 193
 194static void print_raid5_conf (struct r5conf *conf);
 195
 196static int stripe_operations_active(struct stripe_head *sh)
 197{
 198        return sh->check_state || sh->reconstruct_state ||
 199               test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 200               test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 201}
 202
 203static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh)
 204{
 205        BUG_ON(!list_empty(&sh->lru));
 206        BUG_ON(atomic_read(&conf->active_stripes)==0);
 207        if (test_bit(STRIPE_HANDLE, &sh->state)) {
 208                if (test_bit(STRIPE_DELAYED, &sh->state) &&
 209                    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 210                        list_add_tail(&sh->lru, &conf->delayed_list);
 211                else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 212                           sh->bm_seq - conf->seq_write > 0)
 213                        list_add_tail(&sh->lru, &conf->bitmap_list);
 214                else {
 215                        clear_bit(STRIPE_DELAYED, &sh->state);
 216                        clear_bit(STRIPE_BIT_DELAY, &sh->state);
 217                        list_add_tail(&sh->lru, &conf->handle_list);
 218                }
 219                md_wakeup_thread(conf->mddev->thread);
 220        } else {
 221                BUG_ON(stripe_operations_active(sh));
 222                if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 223                        if (atomic_dec_return(&conf->preread_active_stripes)
 224                            < IO_THRESHOLD)
 225                                md_wakeup_thread(conf->mddev->thread);
 226                atomic_dec(&conf->active_stripes);
 227                if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 228                        list_add_tail(&sh->lru, &conf->inactive_list);
 229                        wake_up(&conf->wait_for_stripe);
 230                        if (conf->retry_read_aligned)
 231                                md_wakeup_thread(conf->mddev->thread);
 232                }
 233        }
 234}
 235
 236static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
 237{
 238        if (atomic_dec_and_test(&sh->count))
 239                do_release_stripe(conf, sh);
 240}
 241
 242static void release_stripe(struct stripe_head *sh)
 243{
 244        struct r5conf *conf = sh->raid_conf;
 245        unsigned long flags;
 246
 247        local_irq_save(flags);
 248        if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 249                do_release_stripe(conf, sh);
 250                spin_unlock(&conf->device_lock);
 251        }
 252        local_irq_restore(flags);
 253}
 254
 255static inline void remove_hash(struct stripe_head *sh)
 256{
 257        pr_debug("remove_hash(), stripe %llu\n",
 258                (unsigned long long)sh->sector);
 259
 260        hlist_del_init(&sh->hash);
 261}
 262
 263static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 264{
 265        struct hlist_head *hp = stripe_hash(conf, sh->sector);
 266
 267        pr_debug("insert_hash(), stripe %llu\n",
 268                (unsigned long long)sh->sector);
 269
 270        hlist_add_head(&sh->hash, hp);
 271}
 272
 273
 274/* find an idle stripe, make sure it is unhashed, and return it. */
 275static struct stripe_head *get_free_stripe(struct r5conf *conf)
 276{
 277        struct stripe_head *sh = NULL;
 278        struct list_head *first;
 279
 280        if (list_empty(&conf->inactive_list))
 281                goto out;
 282        first = conf->inactive_list.next;
 283        sh = list_entry(first, struct stripe_head, lru);
 284        list_del_init(first);
 285        remove_hash(sh);
 286        atomic_inc(&conf->active_stripes);
 287out:
 288        return sh;
 289}
 290
 291static void shrink_buffers(struct stripe_head *sh)
 292{
 293        struct page *p;
 294        int i;
 295        int num = sh->raid_conf->pool_size;
 296
 297        for (i = 0; i < num ; i++) {
 298                p = sh->dev[i].page;
 299                if (!p)
 300                        continue;
 301                sh->dev[i].page = NULL;
 302                put_page(p);
 303        }
 304}
 305
 306static int grow_buffers(struct stripe_head *sh)
 307{
 308        int i;
 309        int num = sh->raid_conf->pool_size;
 310
 311        for (i = 0; i < num; i++) {
 312                struct page *page;
 313
 314                if (!(page = alloc_page(GFP_KERNEL))) {
 315                        return 1;
 316                }
 317                sh->dev[i].page = page;
 318        }
 319        return 0;
 320}
 321
 322static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 323static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 324                            struct stripe_head *sh);
 325
 326static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 327{
 328        struct r5conf *conf = sh->raid_conf;
 329        int i;
 330
 331        BUG_ON(atomic_read(&sh->count) != 0);
 332        BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 333        BUG_ON(stripe_operations_active(sh));
 334
 335        pr_debug("init_stripe called, stripe %llu\n",
 336                (unsigned long long)sh->sector);
 337
 338        remove_hash(sh);
 339
 340        sh->generation = conf->generation - previous;
 341        sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 342        sh->sector = sector;
 343        stripe_set_idx(sector, conf, previous, sh);
 344        sh->state = 0;
 345
 346
 347        for (i = sh->disks; i--; ) {
 348                struct r5dev *dev = &sh->dev[i];
 349
 350                if (dev->toread || dev->read || dev->towrite || dev->written ||
 351                    test_bit(R5_LOCKED, &dev->flags)) {
 352                        printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 353                               (unsigned long long)sh->sector, i, dev->toread,
 354                               dev->read, dev->towrite, dev->written,
 355                               test_bit(R5_LOCKED, &dev->flags));
 356                        WARN_ON(1);
 357                }
 358                dev->flags = 0;
 359                raid5_build_block(sh, i, previous);
 360        }
 361        insert_hash(conf, sh);
 362}
 363
 364static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 365                                         short generation)
 366{
 367        struct stripe_head *sh;
 368
 369        pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 370        hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 371                if (sh->sector == sector && sh->generation == generation)
 372                        return sh;
 373        pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 374        return NULL;
 375}
 376
 377/*
 378 * Need to check if array has failed when deciding whether to:
 379 *  - start an array
 380 *  - remove non-faulty devices
 381 *  - add a spare
 382 *  - allow a reshape
 383 * This determination is simple when no reshape is happening.
 384 * However if there is a reshape, we need to carefully check
 385 * both the before and after sections.
 386 * This is because some failed devices may only affect one
 387 * of the two sections, and some non-in_sync devices may
 388 * be insync in the section most affected by failed devices.
 389 */
 390static int calc_degraded(struct r5conf *conf)
 391{
 392        int degraded, degraded2;
 393        int i;
 394
 395        rcu_read_lock();
 396        degraded = 0;
 397        for (i = 0; i < conf->previous_raid_disks; i++) {
 398                struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 399                if (rdev && test_bit(Faulty, &rdev->flags))
 400                        rdev = rcu_dereference(conf->disks[i].replacement);
 401                if (!rdev || test_bit(Faulty, &rdev->flags))
 402                        degraded++;
 403                else if (test_bit(In_sync, &rdev->flags))
 404                        ;
 405                else
 406                        /* not in-sync or faulty.
 407                         * If the reshape increases the number of devices,
 408                         * this is being recovered by the reshape, so
 409                         * this 'previous' section is not in_sync.
 410                         * If the number of devices is being reduced however,
 411                         * the device can only be part of the array if
 412                         * we are reverting a reshape, so this section will
 413                         * be in-sync.
 414                         */
 415                        if (conf->raid_disks >= conf->previous_raid_disks)
 416                                degraded++;
 417        }
 418        rcu_read_unlock();
 419        if (conf->raid_disks == conf->previous_raid_disks)
 420                return degraded;
 421        rcu_read_lock();
 422        degraded2 = 0;
 423        for (i = 0; i < conf->raid_disks; i++) {
 424                struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 425                if (rdev && test_bit(Faulty, &rdev->flags))
 426                        rdev = rcu_dereference(conf->disks[i].replacement);
 427                if (!rdev || test_bit(Faulty, &rdev->flags))
 428                        degraded2++;
 429                else if (test_bit(In_sync, &rdev->flags))
 430                        ;
 431                else
 432                        /* not in-sync or faulty.
 433                         * If reshape increases the number of devices, this
 434                         * section has already been recovered, else it
 435                         * almost certainly hasn't.
 436                         */
 437                        if (conf->raid_disks <= conf->previous_raid_disks)
 438                                degraded2++;
 439        }
 440        rcu_read_unlock();
 441        if (degraded2 > degraded)
 442                return degraded2;
 443        return degraded;
 444}
 445
 446static int has_failed(struct r5conf *conf)
 447{
 448        int degraded;
 449
 450        if (conf->mddev->reshape_position == MaxSector)
 451                return conf->mddev->degraded > conf->max_degraded;
 452
 453        degraded = calc_degraded(conf);
 454        if (degraded > conf->max_degraded)
 455                return 1;
 456        return 0;
 457}
 458
 459static struct stripe_head *
 460get_active_stripe(struct r5conf *conf, sector_t sector,
 461                  int previous, int noblock, int noquiesce)
 462{
 463        struct stripe_head *sh;
 464
 465        pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 466
 467        spin_lock_irq(&conf->device_lock);
 468
 469        do {
 470                wait_event_lock_irq(conf->wait_for_stripe,
 471                                    conf->quiesce == 0 || noquiesce,
 472                                    conf->device_lock);
 473                sh = __find_stripe(conf, sector, conf->generation - previous);
 474                if (!sh) {
 475                        if (!conf->inactive_blocked)
 476                                sh = get_free_stripe(conf);
 477                        if (noblock && sh == NULL)
 478                                break;
 479                        if (!sh) {
 480                                conf->inactive_blocked = 1;
 481                                wait_event_lock_irq(conf->wait_for_stripe,
 482                                                    !list_empty(&conf->inactive_list) &&
 483                                                    (atomic_read(&conf->active_stripes)
 484                                                     < (conf->max_nr_stripes *3/4)
 485                                                     || !conf->inactive_blocked),
 486                                                    conf->device_lock);
 487                                conf->inactive_blocked = 0;
 488                        } else
 489                                init_stripe(sh, sector, previous);
 490                } else {
 491                        if (atomic_read(&sh->count)) {
 492                                BUG_ON(!list_empty(&sh->lru)
 493                                    && !test_bit(STRIPE_EXPANDING, &sh->state)
 494                                    && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
 495                        } else {
 496                                if (!test_bit(STRIPE_HANDLE, &sh->state))
 497                                        atomic_inc(&conf->active_stripes);
 498                                if (list_empty(&sh->lru) &&
 499                                    !test_bit(STRIPE_EXPANDING, &sh->state))
 500                                        BUG();
 501                                list_del_init(&sh->lru);
 502                        }
 503                }
 504        } while (sh == NULL);
 505
 506        if (sh)
 507                atomic_inc(&sh->count);
 508
 509        spin_unlock_irq(&conf->device_lock);
 510        return sh;
 511}
 512
 513/* Determine if 'data_offset' or 'new_data_offset' should be used
 514 * in this stripe_head.
 515 */
 516static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 517{
 518        sector_t progress = conf->reshape_progress;
 519        /* Need a memory barrier to make sure we see the value
 520         * of conf->generation, or ->data_offset that was set before
 521         * reshape_progress was updated.
 522         */
 523        smp_rmb();
 524        if (progress == MaxSector)
 525                return 0;
 526        if (sh->generation == conf->generation - 1)
 527                return 0;
 528        /* We are in a reshape, and this is a new-generation stripe,
 529         * so use new_data_offset.
 530         */
 531        return 1;
 532}
 533
 534static void
 535raid5_end_read_request(struct bio *bi, int error);
 536static void
 537raid5_end_write_request(struct bio *bi, int error);
 538
 539static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 540{
 541        struct r5conf *conf = sh->raid_conf;
 542        int i, disks = sh->disks;
 543
 544        might_sleep();
 545
 546        for (i = disks; i--; ) {
 547                int rw;
 548                int replace_only = 0;
 549                struct bio *bi, *rbi;
 550                struct md_rdev *rdev, *rrdev = NULL;
 551                if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 552                        if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 553                                rw = WRITE_FUA;
 554                        else
 555                                rw = WRITE;
 556                        if (test_bit(R5_Discard, &sh->dev[i].flags))
 557                                rw |= REQ_DISCARD;
 558                } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 559                        rw = READ;
 560                else if (test_and_clear_bit(R5_WantReplace,
 561                                            &sh->dev[i].flags)) {
 562                        rw = WRITE;
 563                        replace_only = 1;
 564                } else
 565                        continue;
 566                if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 567                        rw |= REQ_SYNC;
 568
 569                bi = &sh->dev[i].req;
 570                rbi = &sh->dev[i].rreq; /* For writing to replacement */
 571
 572                bi->bi_rw = rw;
 573                rbi->bi_rw = rw;
 574                if (rw & WRITE) {
 575                        bi->bi_end_io = raid5_end_write_request;
 576                        rbi->bi_end_io = raid5_end_write_request;
 577                } else
 578                        bi->bi_end_io = raid5_end_read_request;
 579
 580                rcu_read_lock();
 581                rrdev = rcu_dereference(conf->disks[i].replacement);
 582                smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 583                rdev = rcu_dereference(conf->disks[i].rdev);
 584                if (!rdev) {
 585                        rdev = rrdev;
 586                        rrdev = NULL;
 587                }
 588                if (rw & WRITE) {
 589                        if (replace_only)
 590                                rdev = NULL;
 591                        if (rdev == rrdev)
 592                                /* We raced and saw duplicates */
 593                                rrdev = NULL;
 594                } else {
 595                        if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
 596                                rdev = rrdev;
 597                        rrdev = NULL;
 598                }
 599
 600                if (rdev && test_bit(Faulty, &rdev->flags))
 601                        rdev = NULL;
 602                if (rdev)
 603                        atomic_inc(&rdev->nr_pending);
 604                if (rrdev && test_bit(Faulty, &rrdev->flags))
 605                        rrdev = NULL;
 606                if (rrdev)
 607                        atomic_inc(&rrdev->nr_pending);
 608                rcu_read_unlock();
 609
 610                /* We have already checked bad blocks for reads.  Now
 611                 * need to check for writes.  We never accept write errors
 612                 * on the replacement, so we don't to check rrdev.
 613                 */
 614                while ((rw & WRITE) && rdev &&
 615                       test_bit(WriteErrorSeen, &rdev->flags)) {
 616                        sector_t first_bad;
 617                        int bad_sectors;
 618                        int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 619                                              &first_bad, &bad_sectors);
 620                        if (!bad)
 621                                break;
 622
 623                        if (bad < 0) {
 624                                set_bit(BlockedBadBlocks, &rdev->flags);
 625                                if (!conf->mddev->external &&
 626                                    conf->mddev->flags) {
 627                                        /* It is very unlikely, but we might
 628                                         * still need to write out the
 629                                         * bad block log - better give it
 630                                         * a chance*/
 631                                        md_check_recovery(conf->mddev);
 632                                }
 633                                /*
 634                                 * Because md_wait_for_blocked_rdev
 635                                 * will dec nr_pending, we must
 636                                 * increment it first.
 637                                 */
 638                                atomic_inc(&rdev->nr_pending);
 639                                md_wait_for_blocked_rdev(rdev, conf->mddev);
 640                        } else {
 641                                /* Acknowledged bad block - skip the write */
 642                                rdev_dec_pending(rdev, conf->mddev);
 643                                rdev = NULL;
 644                        }
 645                }
 646
 647                if (rdev) {
 648                        if (s->syncing || s->expanding || s->expanded
 649                            || s->replacing)
 650                                md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 651
 652                        set_bit(STRIPE_IO_STARTED, &sh->state);
 653
 654                        bi->bi_bdev = rdev->bdev;
 655                        pr_debug("%s: for %llu schedule op %ld on disc %d\n",
 656                                __func__, (unsigned long long)sh->sector,
 657                                bi->bi_rw, i);
 658                        atomic_inc(&sh->count);
 659                        if (use_new_offset(conf, sh))
 660                                bi->bi_sector = (sh->sector
 661                                                 + rdev->new_data_offset);
 662                        else
 663                                bi->bi_sector = (sh->sector
 664                                                 + rdev->data_offset);
 665                        if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
 666                                bi->bi_rw |= REQ_FLUSH;
 667
 668                        bi->bi_flags = 1 << BIO_UPTODATE;
 669                        bi->bi_idx = 0;
 670                        bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 671                        bi->bi_io_vec[0].bv_offset = 0;
 672                        bi->bi_size = STRIPE_SIZE;
 673                        bi->bi_next = NULL;
 674                        if (rrdev)
 675                                set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
 676
 677                        if (conf->mddev->gendisk)
 678                                trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
 679                                                      bi, disk_devt(conf->mddev->gendisk),
 680                                                      sh->dev[i].sector);
 681                        generic_make_request(bi);
 682                }
 683                if (rrdev) {
 684                        if (s->syncing || s->expanding || s->expanded
 685                            || s->replacing)
 686                                md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
 687
 688                        set_bit(STRIPE_IO_STARTED, &sh->state);
 689
 690                        rbi->bi_bdev = rrdev->bdev;
 691                        pr_debug("%s: for %llu schedule op %ld on "
 692                                 "replacement disc %d\n",
 693                                __func__, (unsigned long long)sh->sector,
 694                                rbi->bi_rw, i);
 695                        atomic_inc(&sh->count);
 696                        if (use_new_offset(conf, sh))
 697                                rbi->bi_sector = (sh->sector
 698                                                  + rrdev->new_data_offset);
 699                        else
 700                                rbi->bi_sector = (sh->sector
 701                                                  + rrdev->data_offset);
 702                        rbi->bi_flags = 1 << BIO_UPTODATE;
 703                        rbi->bi_idx = 0;
 704                        rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 705                        rbi->bi_io_vec[0].bv_offset = 0;
 706                        rbi->bi_size = STRIPE_SIZE;
 707                        rbi->bi_next = NULL;
 708                        if (conf->mddev->gendisk)
 709                                trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
 710                                                      rbi, disk_devt(conf->mddev->gendisk),
 711                                                      sh->dev[i].sector);
 712                        generic_make_request(rbi);
 713                }
 714                if (!rdev && !rrdev) {
 715                        if (rw & WRITE)
 716                                set_bit(STRIPE_DEGRADED, &sh->state);
 717                        pr_debug("skip op %ld on disc %d for sector %llu\n",
 718                                bi->bi_rw, i, (unsigned long long)sh->sector);
 719                        clear_bit(R5_LOCKED, &sh->dev[i].flags);
 720                        set_bit(STRIPE_HANDLE, &sh->state);
 721                }
 722        }
 723}
 724
 725static struct dma_async_tx_descriptor *
 726async_copy_data(int frombio, struct bio *bio, struct page *page,
 727        sector_t sector, struct dma_async_tx_descriptor *tx)
 728{
 729        struct bio_vec *bvl;
 730        struct page *bio_page;
 731        int i;
 732        int page_offset;
 733        struct async_submit_ctl submit;
 734        enum async_tx_flags flags = 0;
 735
 736        if (bio->bi_sector >= sector)
 737                page_offset = (signed)(bio->bi_sector - sector) * 512;
 738        else
 739                page_offset = (signed)(sector - bio->bi_sector) * -512;
 740
 741        if (frombio)
 742                flags |= ASYNC_TX_FENCE;
 743        init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
 744
 745        bio_for_each_segment(bvl, bio, i) {
 746                int len = bvl->bv_len;
 747                int clen;
 748                int b_offset = 0;
 749
 750                if (page_offset < 0) {
 751                        b_offset = -page_offset;
 752                        page_offset += b_offset;
 753                        len -= b_offset;
 754                }
 755
 756                if (len > 0 && page_offset + len > STRIPE_SIZE)
 757                        clen = STRIPE_SIZE - page_offset;
 758                else
 759                        clen = len;
 760
 761                if (clen > 0) {
 762                        b_offset += bvl->bv_offset;
 763                        bio_page = bvl->bv_page;
 764                        if (frombio)
 765                                tx = async_memcpy(page, bio_page, page_offset,
 766                                                  b_offset, clen, &submit);
 767                        else
 768                                tx = async_memcpy(bio_page, page, b_offset,
 769                                                  page_offset, clen, &submit);
 770                }
 771                /* chain the operations */
 772                submit.depend_tx = tx;
 773
 774                if (clen < len) /* hit end of page */
 775                        break;
 776                page_offset +=  len;
 777        }
 778
 779        return tx;
 780}
 781
 782static void ops_complete_biofill(void *stripe_head_ref)
 783{
 784        struct stripe_head *sh = stripe_head_ref;
 785        struct bio *return_bi = NULL;
 786        int i;
 787
 788        pr_debug("%s: stripe %llu\n", __func__,
 789                (unsigned long long)sh->sector);
 790
 791        /* clear completed biofills */
 792        for (i = sh->disks; i--; ) {
 793                struct r5dev *dev = &sh->dev[i];
 794
 795                /* acknowledge completion of a biofill operation */
 796                /* and check if we need to reply to a read request,
 797                 * new R5_Wantfill requests are held off until
 798                 * !STRIPE_BIOFILL_RUN
 799                 */
 800                if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
 801                        struct bio *rbi, *rbi2;
 802
 803                        BUG_ON(!dev->read);
 804                        rbi = dev->read;
 805                        dev->read = NULL;
 806                        while (rbi && rbi->bi_sector <
 807                                dev->sector + STRIPE_SECTORS) {
 808                                rbi2 = r5_next_bio(rbi, dev->sector);
 809                                if (!raid5_dec_bi_active_stripes(rbi)) {
 810                                        rbi->bi_next = return_bi;
 811                                        return_bi = rbi;
 812                                }
 813                                rbi = rbi2;
 814                        }
 815                }
 816        }
 817        clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
 818
 819        return_io(return_bi);
 820
 821        set_bit(STRIPE_HANDLE, &sh->state);
 822        release_stripe(sh);
 823}
 824
 825static void ops_run_biofill(struct stripe_head *sh)
 826{
 827        struct dma_async_tx_descriptor *tx = NULL;
 828        struct async_submit_ctl submit;
 829        int i;
 830
 831        pr_debug("%s: stripe %llu\n", __func__,
 832                (unsigned long long)sh->sector);
 833
 834        for (i = sh->disks; i--; ) {
 835                struct r5dev *dev = &sh->dev[i];
 836                if (test_bit(R5_Wantfill, &dev->flags)) {
 837                        struct bio *rbi;
 838                        spin_lock_irq(&sh->stripe_lock);
 839                        dev->read = rbi = dev->toread;
 840                        dev->toread = NULL;
 841                        spin_unlock_irq(&sh->stripe_lock);
 842                        while (rbi && rbi->bi_sector <
 843                                dev->sector + STRIPE_SECTORS) {
 844                                tx = async_copy_data(0, rbi, dev->page,
 845                                        dev->sector, tx);
 846                                rbi = r5_next_bio(rbi, dev->sector);
 847                        }
 848                }
 849        }
 850
 851        atomic_inc(&sh->count);
 852        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
 853        async_trigger_callback(&submit);
 854}
 855
 856static void mark_target_uptodate(struct stripe_head *sh, int target)
 857{
 858        struct r5dev *tgt;
 859
 860        if (target < 0)
 861                return;
 862
 863        tgt = &sh->dev[target];
 864        set_bit(R5_UPTODATE, &tgt->flags);
 865        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 866        clear_bit(R5_Wantcompute, &tgt->flags);
 867}
 868
 869static void ops_complete_compute(void *stripe_head_ref)
 870{
 871        struct stripe_head *sh = stripe_head_ref;
 872
 873        pr_debug("%s: stripe %llu\n", __func__,
 874                (unsigned long long)sh->sector);
 875
 876        /* mark the computed target(s) as uptodate */
 877        mark_target_uptodate(sh, sh->ops.target);
 878        mark_target_uptodate(sh, sh->ops.target2);
 879
 880        clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
 881        if (sh->check_state == check_state_compute_run)
 882                sh->check_state = check_state_compute_result;
 883        set_bit(STRIPE_HANDLE, &sh->state);
 884        release_stripe(sh);
 885}
 886
 887/* return a pointer to the address conversion region of the scribble buffer */
 888static addr_conv_t *to_addr_conv(struct stripe_head *sh,
 889                                 struct raid5_percpu *percpu)
 890{
 891        return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
 892}
 893
 894static struct dma_async_tx_descriptor *
 895ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
 896{
 897        int disks = sh->disks;
 898        struct page **xor_srcs = percpu->scribble;
 899        int target = sh->ops.target;
 900        struct r5dev *tgt = &sh->dev[target];
 901        struct page *xor_dest = tgt->page;
 902        int count = 0;
 903        struct dma_async_tx_descriptor *tx;
 904        struct async_submit_ctl submit;
 905        int i;
 906
 907        pr_debug("%s: stripe %llu block: %d\n",
 908                __func__, (unsigned long long)sh->sector, target);
 909        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 910
 911        for (i = disks; i--; )
 912                if (i != target)
 913                        xor_srcs[count++] = sh->dev[i].page;
 914
 915        atomic_inc(&sh->count);
 916
 917        init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
 918                          ops_complete_compute, sh, to_addr_conv(sh, percpu));
 919        if (unlikely(count == 1))
 920                tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
 921        else
 922                tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
 923
 924        return tx;
 925}
 926
 927/* set_syndrome_sources - populate source buffers for gen_syndrome
 928 * @srcs - (struct page *) array of size sh->disks
 929 * @sh - stripe_head to parse
 930 *
 931 * Populates srcs in proper layout order for the stripe and returns the
 932 * 'count' of sources to be used in a call to async_gen_syndrome.  The P
 933 * destination buffer is recorded in srcs[count] and the Q destination
 934 * is recorded in srcs[count+1]].
 935 */
 936static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
 937{
 938        int disks = sh->disks;
 939        int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
 940        int d0_idx = raid6_d0(sh);
 941        int count;
 942        int i;
 943
 944        for (i = 0; i < disks; i++)
 945                srcs[i] = NULL;
 946
 947        count = 0;
 948        i = d0_idx;
 949        do {
 950                int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
 951
 952                srcs[slot] = sh->dev[i].page;
 953                i = raid6_next_disk(i, disks);
 954        } while (i != d0_idx);
 955
 956        return syndrome_disks;
 957}
 958
 959static struct dma_async_tx_descriptor *
 960ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
 961{
 962        int disks = sh->disks;
 963        struct page **blocks = percpu->scribble;
 964        int target;
 965        int qd_idx = sh->qd_idx;
 966        struct dma_async_tx_descriptor *tx;
 967        struct async_submit_ctl submit;
 968        struct r5dev *tgt;
 969        struct page *dest;
 970        int i;
 971        int count;
 972
 973        if (sh->ops.target < 0)
 974                target = sh->ops.target2;
 975        else if (sh->ops.target2 < 0)
 976                target = sh->ops.target;
 977        else
 978                /* we should only have one valid target */
 979                BUG();
 980        BUG_ON(target < 0);
 981        pr_debug("%s: stripe %llu block: %d\n",
 982                __func__, (unsigned long long)sh->sector, target);
 983
 984        tgt = &sh->dev[target];
 985        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 986        dest = tgt->page;
 987
 988        atomic_inc(&sh->count);
 989
 990        if (target == qd_idx) {
 991                count = set_syndrome_sources(blocks, sh);
 992                blocks[count] = NULL; /* regenerating p is not necessary */
 993                BUG_ON(blocks[count+1] != dest); /* q should already be set */
 994                init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
 995                                  ops_complete_compute, sh,
 996                                  to_addr_conv(sh, percpu));
 997                tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
 998        } else {
 999                /* Compute any data- or p-drive using XOR */
1000                count = 0;
1001                for (i = disks; i-- ; ) {
1002                        if (i == target || i == qd_idx)
1003                                continue;
1004                        blocks[count++] = sh->dev[i].page;
1005                }
1006
1007                init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1008                                  NULL, ops_complete_compute, sh,
1009                                  to_addr_conv(sh, percpu));
1010                tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1011        }
1012
1013        return tx;
1014}
1015
1016static struct dma_async_tx_descriptor *
1017ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1018{
1019        int i, count, disks = sh->disks;
1020        int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1021        int d0_idx = raid6_d0(sh);
1022        int faila = -1, failb = -1;
1023        int target = sh->ops.target;
1024        int target2 = sh->ops.target2;
1025        struct r5dev *tgt = &sh->dev[target];
1026        struct r5dev *tgt2 = &sh->dev[target2];
1027        struct dma_async_tx_descriptor *tx;
1028        struct page **blocks = percpu->scribble;
1029        struct async_submit_ctl submit;
1030
1031        pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1032                 __func__, (unsigned long long)sh->sector, target, target2);
1033        BUG_ON(target < 0 || target2 < 0);
1034        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1035        BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1036
1037        /* we need to open-code set_syndrome_sources to handle the
1038         * slot number conversion for 'faila' and 'failb'
1039         */
1040        for (i = 0; i < disks ; i++)
1041                blocks[i] = NULL;
1042        count = 0;
1043        i = d0_idx;
1044        do {
1045                int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1046
1047                blocks[slot] = sh->dev[i].page;
1048
1049                if (i == target)
1050                        faila = slot;
1051                if (i == target2)
1052                        failb = slot;
1053                i = raid6_next_disk(i, disks);
1054        } while (i != d0_idx);
1055
1056        BUG_ON(faila == failb);
1057        if (failb < faila)
1058                swap(faila, failb);
1059        pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1060                 __func__, (unsigned long long)sh->sector, faila, failb);
1061
1062        atomic_inc(&sh->count);
1063
1064        if (failb == syndrome_disks+1) {
1065                /* Q disk is one of the missing disks */
1066                if (faila == syndrome_disks) {
1067                        /* Missing P+Q, just recompute */
1068                        init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1069                                          ops_complete_compute, sh,
1070                                          to_addr_conv(sh, percpu));
1071                        return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1072                                                  STRIPE_SIZE, &submit);
1073                } else {
1074                        struct page *dest;
1075                        int data_target;
1076                        int qd_idx = sh->qd_idx;
1077
1078                        /* Missing D+Q: recompute D from P, then recompute Q */
1079                        if (target == qd_idx)
1080                                data_target = target2;
1081                        else
1082                                data_target = target;
1083
1084                        count = 0;
1085                        for (i = disks; i-- ; ) {
1086                                if (i == data_target || i == qd_idx)
1087                                        continue;
1088                                blocks[count++] = sh->dev[i].page;
1089                        }
1090                        dest = sh->dev[data_target].page;
1091                        init_async_submit(&submit,
1092                                          ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1093                                          NULL, NULL, NULL,
1094                                          to_addr_conv(sh, percpu));
1095                        tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1096                                       &submit);
1097
1098                        count = set_syndrome_sources(blocks, sh);
1099                        init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1100                                          ops_complete_compute, sh,
1101                                          to_addr_conv(sh, percpu));
1102                        return async_gen_syndrome(blocks, 0, count+2,
1103                                                  STRIPE_SIZE, &submit);
1104                }
1105        } else {
1106                init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1107                                  ops_complete_compute, sh,
1108                                  to_addr_conv(sh, percpu));
1109                if (failb == syndrome_disks) {
1110                        /* We're missing D+P. */
1111                        return async_raid6_datap_recov(syndrome_disks+2,
1112                                                       STRIPE_SIZE, faila,
1113                                                       blocks, &submit);
1114                } else {
1115                        /* We're missing D+D. */
1116                        return async_raid6_2data_recov(syndrome_disks+2,
1117                                                       STRIPE_SIZE, faila, failb,
1118                                                       blocks, &submit);
1119                }
1120        }
1121}
1122
1123
1124static void ops_complete_prexor(void *stripe_head_ref)
1125{
1126        struct stripe_head *sh = stripe_head_ref;
1127
1128        pr_debug("%s: stripe %llu\n", __func__,
1129                (unsigned long long)sh->sector);
1130}
1131
1132static struct dma_async_tx_descriptor *
1133ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1134               struct dma_async_tx_descriptor *tx)
1135{
1136        int disks = sh->disks;
1137        struct page **xor_srcs = percpu->scribble;
1138        int count = 0, pd_idx = sh->pd_idx, i;
1139        struct async_submit_ctl submit;
1140
1141        /* existing parity data subtracted */
1142        struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1143
1144        pr_debug("%s: stripe %llu\n", __func__,
1145                (unsigned long long)sh->sector);
1146
1147        for (i = disks; i--; ) {
1148                struct r5dev *dev = &sh->dev[i];
1149                /* Only process blocks that are known to be uptodate */
1150                if (test_bit(R5_Wantdrain, &dev->flags))
1151                        xor_srcs[count++] = dev->page;
1152        }
1153
1154        init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1155                          ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1156        tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1157
1158        return tx;
1159}
1160
1161static struct dma_async_tx_descriptor *
1162ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1163{
1164        int disks = sh->disks;
1165        int i;
1166
1167        pr_debug("%s: stripe %llu\n", __func__,
1168                (unsigned long long)sh->sector);
1169
1170        for (i = disks; i--; ) {
1171                struct r5dev *dev = &sh->dev[i];
1172                struct bio *chosen;
1173
1174                if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1175                        struct bio *wbi;
1176
1177                        spin_lock_irq(&sh->stripe_lock);
1178                        chosen = dev->towrite;
1179                        dev->towrite = NULL;
1180                        BUG_ON(dev->written);
1181                        wbi = dev->written = chosen;
1182                        spin_unlock_irq(&sh->stripe_lock);
1183
1184                        while (wbi && wbi->bi_sector <
1185                                dev->sector + STRIPE_SECTORS) {
1186                                if (wbi->bi_rw & REQ_FUA)
1187                                        set_bit(R5_WantFUA, &dev->flags);
1188                                if (wbi->bi_rw & REQ_SYNC)
1189                                        set_bit(R5_SyncIO, &dev->flags);
1190                                if (wbi->bi_rw & REQ_DISCARD)
1191                                        set_bit(R5_Discard, &dev->flags);
1192                                else
1193                                        tx = async_copy_data(1, wbi, dev->page,
1194                                                dev->sector, tx);
1195                                wbi = r5_next_bio(wbi, dev->sector);
1196                        }
1197                }
1198        }
1199
1200        return tx;
1201}
1202
1203static void ops_complete_reconstruct(void *stripe_head_ref)
1204{
1205        struct stripe_head *sh = stripe_head_ref;
1206        int disks = sh->disks;
1207        int pd_idx = sh->pd_idx;
1208        int qd_idx = sh->qd_idx;
1209        int i;
1210        bool fua = false, sync = false, discard = false;
1211
1212        pr_debug("%s: stripe %llu\n", __func__,
1213                (unsigned long long)sh->sector);
1214
1215        for (i = disks; i--; ) {
1216                fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1217                sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1218                discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1219        }
1220
1221        for (i = disks; i--; ) {
1222                struct r5dev *dev = &sh->dev[i];
1223
1224                if (dev->written || i == pd_idx || i == qd_idx) {
1225                        if (!discard)
1226                                set_bit(R5_UPTODATE, &dev->flags);
1227                        if (fua)
1228                                set_bit(R5_WantFUA, &dev->flags);
1229                        if (sync)
1230                                set_bit(R5_SyncIO, &dev->flags);
1231                }
1232        }
1233
1234        if (sh->reconstruct_state == reconstruct_state_drain_run)
1235                sh->reconstruct_state = reconstruct_state_drain_result;
1236        else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1237                sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1238        else {
1239                BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1240                sh->reconstruct_state = reconstruct_state_result;
1241        }
1242
1243        set_bit(STRIPE_HANDLE, &sh->state);
1244        release_stripe(sh);
1245}
1246
1247static void
1248ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1249                     struct dma_async_tx_descriptor *tx)
1250{
1251        int disks = sh->disks;
1252        struct page **xor_srcs = percpu->scribble;
1253        struct async_submit_ctl submit;
1254        int count = 0, pd_idx = sh->pd_idx, i;
1255        struct page *xor_dest;
1256        int prexor = 0;
1257        unsigned long flags;
1258
1259        pr_debug("%s: stripe %llu\n", __func__,
1260                (unsigned long long)sh->sector);
1261
1262        for (i = 0; i < sh->disks; i++) {
1263                if (pd_idx == i)
1264                        continue;
1265                if (!test_bit(R5_Discard, &sh->dev[i].flags))
1266                        break;
1267        }
1268        if (i >= sh->disks) {
1269                atomic_inc(&sh->count);
1270                set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1271                ops_complete_reconstruct(sh);
1272                return;
1273        }
1274        /* check if prexor is active which means only process blocks
1275         * that are part of a read-modify-write (written)
1276         */
1277        if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1278                prexor = 1;
1279                xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1280                for (i = disks; i--; ) {
1281                        struct r5dev *dev = &sh->dev[i];
1282                        if (dev->written)
1283                                xor_srcs[count++] = dev->page;
1284                }
1285        } else {
1286                xor_dest = sh->dev[pd_idx].page;
1287                for (i = disks; i--; ) {
1288                        struct r5dev *dev = &sh->dev[i];
1289                        if (i != pd_idx)
1290                                xor_srcs[count++] = dev->page;
1291                }
1292        }
1293
1294        /* 1/ if we prexor'd then the dest is reused as a source
1295         * 2/ if we did not prexor then we are redoing the parity
1296         * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1297         * for the synchronous xor case
1298         */
1299        flags = ASYNC_TX_ACK |
1300                (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1301
1302        atomic_inc(&sh->count);
1303
1304        init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1305                          to_addr_conv(sh, percpu));
1306        if (unlikely(count == 1))
1307                tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1308        else
1309                tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1310}
1311
1312static void
1313ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1314                     struct dma_async_tx_descriptor *tx)
1315{
1316        struct async_submit_ctl submit;
1317        struct page **blocks = percpu->scribble;
1318        int count, i;
1319
1320        pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1321
1322        for (i = 0; i < sh->disks; i++) {
1323                if (sh->pd_idx == i || sh->qd_idx == i)
1324                        continue;
1325                if (!test_bit(R5_Discard, &sh->dev[i].flags))
1326                        break;
1327        }
1328        if (i >= sh->disks) {
1329                atomic_inc(&sh->count);
1330                set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1331                set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1332                ops_complete_reconstruct(sh);
1333                return;
1334        }
1335
1336        count = set_syndrome_sources(blocks, sh);
1337
1338        atomic_inc(&sh->count);
1339
1340        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1341                          sh, to_addr_conv(sh, percpu));
1342        async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1343}
1344
1345static void ops_complete_check(void *stripe_head_ref)
1346{
1347        struct stripe_head *sh = stripe_head_ref;
1348
1349        pr_debug("%s: stripe %llu\n", __func__,
1350                (unsigned long long)sh->sector);
1351
1352        sh->check_state = check_state_check_result;
1353        set_bit(STRIPE_HANDLE, &sh->state);
1354        release_stripe(sh);
1355}
1356
1357static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1358{
1359        int disks = sh->disks;
1360        int pd_idx = sh->pd_idx;
1361        int qd_idx = sh->qd_idx;
1362        struct page *xor_dest;
1363        struct page **xor_srcs = percpu->scribble;
1364        struct dma_async_tx_descriptor *tx;
1365        struct async_submit_ctl submit;
1366        int count;
1367        int i;
1368
1369        pr_debug("%s: stripe %llu\n", __func__,
1370                (unsigned long long)sh->sector);
1371
1372        count = 0;
1373        xor_dest = sh->dev[pd_idx].page;
1374        xor_srcs[count++] = xor_dest;
1375        for (i = disks; i--; ) {
1376                if (i == pd_idx || i == qd_idx)
1377                        continue;
1378                xor_srcs[count++] = sh->dev[i].page;
1379        }
1380
1381        init_async_submit(&submit, 0, NULL, NULL, NULL,
1382                          to_addr_conv(sh, percpu));
1383        tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1384                           &sh->ops.zero_sum_result, &submit);
1385
1386        atomic_inc(&sh->count);
1387        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1388        tx = async_trigger_callback(&submit);
1389}
1390
1391static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1392{
1393        struct page **srcs = percpu->scribble;
1394        struct async_submit_ctl submit;
1395        int count;
1396
1397        pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1398                (unsigned long long)sh->sector, checkp);
1399
1400        count = set_syndrome_sources(srcs, sh);
1401        if (!checkp)
1402                srcs[count] = NULL;
1403
1404        atomic_inc(&sh->count);
1405        init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1406                          sh, to_addr_conv(sh, percpu));
1407        async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1408                           &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1409}
1410
1411static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1412{
1413        int overlap_clear = 0, i, disks = sh->disks;
1414        struct dma_async_tx_descriptor *tx = NULL;
1415        struct r5conf *conf = sh->raid_conf;
1416        int level = conf->level;
1417        struct raid5_percpu *percpu;
1418        unsigned long cpu;
1419
1420        cpu = get_cpu();
1421        percpu = per_cpu_ptr(conf->percpu, cpu);
1422        if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1423                ops_run_biofill(sh);
1424                overlap_clear++;
1425        }
1426
1427        if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1428                if (level < 6)
1429                        tx = ops_run_compute5(sh, percpu);
1430                else {
1431                        if (sh->ops.target2 < 0 || sh->ops.target < 0)
1432                                tx = ops_run_compute6_1(sh, percpu);
1433                        else
1434                                tx = ops_run_compute6_2(sh, percpu);
1435                }
1436                /* terminate the chain if reconstruct is not set to be run */
1437                if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1438                        async_tx_ack(tx);
1439        }
1440
1441        if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1442                tx = ops_run_prexor(sh, percpu, tx);
1443
1444        if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1445                tx = ops_run_biodrain(sh, tx);
1446                overlap_clear++;
1447        }
1448
1449        if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1450                if (level < 6)
1451                        ops_run_reconstruct5(sh, percpu, tx);
1452                else
1453                        ops_run_reconstruct6(sh, percpu, tx);
1454        }
1455
1456        if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1457                if (sh->check_state == check_state_run)
1458                        ops_run_check_p(sh, percpu);
1459                else if (sh->check_state == check_state_run_q)
1460                        ops_run_check_pq(sh, percpu, 0);
1461                else if (sh->check_state == check_state_run_pq)
1462                        ops_run_check_pq(sh, percpu, 1);
1463                else
1464                        BUG();
1465        }
1466
1467        if (overlap_clear)
1468                for (i = disks; i--; ) {
1469                        struct r5dev *dev = &sh->dev[i];
1470                        if (test_and_clear_bit(R5_Overlap, &dev->flags))
1471                                wake_up(&sh->raid_conf->wait_for_overlap);
1472                }
1473        put_cpu();
1474}
1475
1476static int grow_one_stripe(struct r5conf *conf)
1477{
1478        struct stripe_head *sh;
1479        sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1480        if (!sh)
1481                return 0;
1482
1483        sh->raid_conf = conf;
1484
1485        spin_lock_init(&sh->stripe_lock);
1486
1487        if (grow_buffers(sh)) {
1488                shrink_buffers(sh);
1489                kmem_cache_free(conf->slab_cache, sh);
1490                return 0;
1491        }
1492        /* we just created an active stripe so... */
1493        atomic_set(&sh->count, 1);
1494        atomic_inc(&conf->active_stripes);
1495        INIT_LIST_HEAD(&sh->lru);
1496        release_stripe(sh);
1497        return 1;
1498}
1499
1500static int grow_stripes(struct r5conf *conf, int num)
1501{
1502        struct kmem_cache *sc;
1503        int devs = max(conf->raid_disks, conf->previous_raid_disks);
1504
1505        if (conf->mddev->gendisk)
1506                sprintf(conf->cache_name[0],
1507                        "raid%d-%s", conf->level, mdname(conf->mddev));
1508        else
1509                sprintf(conf->cache_name[0],
1510                        "raid%d-%p", conf->level, conf->mddev);
1511        sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1512
1513        conf->active_name = 0;
1514        sc = kmem_cache_create(conf->cache_name[conf->active_name],
1515                               sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1516                               0, 0, NULL);
1517        if (!sc)
1518                return 1;
1519        conf->slab_cache = sc;
1520        conf->pool_size = devs;
1521        while (num--)
1522                if (!grow_one_stripe(conf))
1523                        return 1;
1524        return 0;
1525}
1526
1527/**
1528 * scribble_len - return the required size of the scribble region
1529 * @num - total number of disks in the array
1530 *
1531 * The size must be enough to contain:
1532 * 1/ a struct page pointer for each device in the array +2
1533 * 2/ room to convert each entry in (1) to its corresponding dma
1534 *    (dma_map_page()) or page (page_address()) address.
1535 *
1536 * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1537 * calculate over all devices (not just the data blocks), using zeros in place
1538 * of the P and Q blocks.
1539 */
1540static size_t scribble_len(int num)
1541{
1542        size_t len;
1543
1544        len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1545
1546        return len;
1547}
1548
1549static int resize_stripes(struct r5conf *conf, int newsize)
1550{
1551        /* Make all the stripes able to hold 'newsize' devices.
1552         * New slots in each stripe get 'page' set to a new page.
1553         *
1554         * This happens in stages:
1555         * 1/ create a new kmem_cache and allocate the required number of
1556         *    stripe_heads.
1557         * 2/ gather all the old stripe_heads and transfer the pages across
1558         *    to the new stripe_heads.  This will have the side effect of
1559         *    freezing the array as once all stripe_heads have been collected,
1560         *    no IO will be possible.  Old stripe heads are freed once their
1561         *    pages have been transferred over, and the old kmem_cache is
1562         *    freed when all stripes are done.
1563         * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1564         *    we simple return a failre status - no need to clean anything up.
1565         * 4/ allocate new pages for the new slots in the new stripe_heads.
1566         *    If this fails, we don't bother trying the shrink the
1567         *    stripe_heads down again, we just leave them as they are.
1568         *    As each stripe_head is processed the new one is released into
1569         *    active service.
1570         *
1571         * Once step2 is started, we cannot afford to wait for a write,
1572         * so we use GFP_NOIO allocations.
1573         */
1574        struct stripe_head *osh, *nsh;
1575        LIST_HEAD(newstripes);
1576        struct disk_info *ndisks;
1577        unsigned long cpu;
1578        int err;
1579        struct kmem_cache *sc;
1580        int i;
1581
1582        if (newsize <= conf->pool_size)
1583                return 0; /* never bother to shrink */
1584
1585        err = md_allow_write(conf->mddev);
1586        if (err)
1587                return err;
1588
1589        /* Step 1 */
1590        sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1591                               sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1592                               0, 0, NULL);
1593        if (!sc)
1594                return -ENOMEM;
1595
1596        for (i = conf->max_nr_stripes; i; i--) {
1597                nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1598                if (!nsh)
1599                        break;
1600
1601                nsh->raid_conf = conf;
1602                spin_lock_init(&nsh->stripe_lock);
1603
1604                list_add(&nsh->lru, &newstripes);
1605        }
1606        if (i) {
1607                /* didn't get enough, give up */
1608                while (!list_empty(&newstripes)) {
1609                        nsh = list_entry(newstripes.next, struct stripe_head, lru);
1610                        list_del(&nsh->lru);
1611                        kmem_cache_free(sc, nsh);
1612                }
1613                kmem_cache_destroy(sc);
1614                return -ENOMEM;
1615        }
1616        /* Step 2 - Must use GFP_NOIO now.
1617         * OK, we have enough stripes, start collecting inactive
1618         * stripes and copying them over
1619         */
1620        list_for_each_entry(nsh, &newstripes, lru) {
1621                spin_lock_irq(&conf->device_lock);
1622                wait_event_lock_irq(conf->wait_for_stripe,
1623                                    !list_empty(&conf->inactive_list),
1624                                    conf->device_lock);
1625                osh = get_free_stripe(conf);
1626                spin_unlock_irq(&conf->device_lock);
1627                atomic_set(&nsh->count, 1);
1628                for(i=0; i<conf->pool_size; i++)
1629                        nsh->dev[i].page = osh->dev[i].page;
1630                for( ; i<newsize; i++)
1631                        nsh->dev[i].page = NULL;
1632                kmem_cache_free(conf->slab_cache, osh);
1633        }
1634        kmem_cache_destroy(conf->slab_cache);
1635
1636        /* Step 3.
1637         * At this point, we are holding all the stripes so the array
1638         * is completely stalled, so now is a good time to resize
1639         * conf->disks and the scribble region
1640         */
1641        ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1642        if (ndisks) {
1643                for (i=0; i<conf->raid_disks; i++)
1644                        ndisks[i] = conf->disks[i];
1645                kfree(conf->disks);
1646                conf->disks = ndisks;
1647        } else
1648                err = -ENOMEM;
1649
1650        get_online_cpus();
1651        conf->scribble_len = scribble_len(newsize);
1652        for_each_present_cpu(cpu) {
1653                struct raid5_percpu *percpu;
1654                void *scribble;
1655
1656                percpu = per_cpu_ptr(conf->percpu, cpu);
1657                scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1658
1659                if (scribble) {
1660                        kfree(percpu->scribble);
1661                        percpu->scribble = scribble;
1662                } else {
1663                        err = -ENOMEM;
1664                        break;
1665                }
1666        }
1667        put_online_cpus();
1668
1669        /* Step 4, return new stripes to service */
1670        while(!list_empty(&newstripes)) {
1671                nsh = list_entry(newstripes.next, struct stripe_head, lru);
1672                list_del_init(&nsh->lru);
1673
1674                for (i=conf->raid_disks; i < newsize; i++)
1675                        if (nsh->dev[i].page == NULL) {
1676                                struct page *p = alloc_page(GFP_NOIO);
1677                                nsh->dev[i].page = p;
1678                                if (!p)
1679                                        err = -ENOMEM;
1680                        }
1681                release_stripe(nsh);
1682        }
1683        /* critical section pass, GFP_NOIO no longer needed */
1684
1685        conf->slab_cache = sc;
1686        conf->active_name = 1-conf->active_name;
1687        conf->pool_size = newsize;
1688        return err;
1689}
1690
1691static int drop_one_stripe(struct r5conf *conf)
1692{
1693        struct stripe_head *sh;
1694
1695        spin_lock_irq(&conf->device_lock);
1696        sh = get_free_stripe(conf);
1697        spin_unlock_irq(&conf->device_lock);
1698        if (!sh)
1699                return 0;
1700        BUG_ON(atomic_read(&sh->count));
1701        shrink_buffers(sh);
1702        kmem_cache_free(conf->slab_cache, sh);
1703        atomic_dec(&conf->active_stripes);
1704        return 1;
1705}
1706
1707static void shrink_stripes(struct r5conf *conf)
1708{
1709        while (drop_one_stripe(conf))
1710                ;
1711
1712        if (conf->slab_cache)
1713                kmem_cache_destroy(conf->slab_cache);
1714        conf->slab_cache = NULL;
1715}
1716
1717static void raid5_end_read_request(struct bio * bi, int error)
1718{
1719        struct stripe_head *sh = bi->bi_private;
1720        struct r5conf *conf = sh->raid_conf;
1721        int disks = sh->disks, i;
1722        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1723        char b[BDEVNAME_SIZE];
1724        struct md_rdev *rdev = NULL;
1725        sector_t s;
1726
1727        for (i=0 ; i<disks; i++)
1728                if (bi == &sh->dev[i].req)
1729                        break;
1730
1731        pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1732                (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1733                uptodate);
1734        if (i == disks) {
1735                BUG();
1736                return;
1737        }
1738        if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1739                /* If replacement finished while this request was outstanding,
1740                 * 'replacement' might be NULL already.
1741                 * In that case it moved down to 'rdev'.
1742                 * rdev is not removed until all requests are finished.
1743                 */
1744                rdev = conf->disks[i].replacement;
1745        if (!rdev)
1746                rdev = conf->disks[i].rdev;
1747
1748        if (use_new_offset(conf, sh))
1749                s = sh->sector + rdev->new_data_offset;
1750        else
1751                s = sh->sector + rdev->data_offset;
1752        if (uptodate) {
1753                set_bit(R5_UPTODATE, &sh->dev[i].flags);
1754                if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1755                        /* Note that this cannot happen on a
1756                         * replacement device.  We just fail those on
1757                         * any error
1758                         */
1759                        printk_ratelimited(
1760                                KERN_INFO
1761                                "md/raid:%s: read error corrected"
1762                                " (%lu sectors at %llu on %s)\n",
1763                                mdname(conf->mddev), STRIPE_SECTORS,
1764                                (unsigned long long)s,
1765                                bdevname(rdev->bdev, b));
1766                        atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1767                        clear_bit(R5_ReadError, &sh->dev[i].flags);
1768                        clear_bit(R5_ReWrite, &sh->dev[i].flags);
1769                } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
1770                        clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1771
1772                if (atomic_read(&rdev->read_errors))
1773                        atomic_set(&rdev->read_errors, 0);
1774        } else {
1775                const char *bdn = bdevname(rdev->bdev, b);
1776                int retry = 0;
1777                int set_bad = 0;
1778
1779                clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1780                atomic_inc(&rdev->read_errors);
1781                if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1782                        printk_ratelimited(
1783                                KERN_WARNING
1784                                "md/raid:%s: read error on replacement device "
1785                                "(sector %llu on %s).\n",
1786                                mdname(conf->mddev),
1787                                (unsigned long long)s,
1788                                bdn);
1789                else if (conf->mddev->degraded >= conf->max_degraded) {
1790                        set_bad = 1;
1791                        printk_ratelimited(
1792                                KERN_WARNING
1793                                "md/raid:%s: read error not correctable "
1794                                "(sector %llu on %s).\n",
1795                                mdname(conf->mddev),
1796                                (unsigned long long)s,
1797                                bdn);
1798                } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
1799                        /* Oh, no!!! */
1800                        set_bad = 1;
1801                        printk_ratelimited(
1802                                KERN_WARNING
1803                                "md/raid:%s: read error NOT corrected!! "
1804                                "(sector %llu on %s).\n",
1805                                mdname(conf->mddev),
1806                                (unsigned long long)s,
1807                                bdn);
1808                } else if (atomic_read(&rdev->read_errors)
1809                         > conf->max_nr_stripes)
1810                        printk(KERN_WARNING
1811                               "md/raid:%s: Too many read errors, failing device %s.\n",
1812                               mdname(conf->mddev), bdn);
1813                else
1814                        retry = 1;
1815                if (retry)
1816                        if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
1817                                set_bit(R5_ReadError, &sh->dev[i].flags);
1818                                clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1819                        } else
1820                                set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1821                else {
1822                        clear_bit(R5_ReadError, &sh->dev[i].flags);
1823                        clear_bit(R5_ReWrite, &sh->dev[i].flags);
1824                        if (!(set_bad
1825                              && test_bit(In_sync, &rdev->flags)
1826                              && rdev_set_badblocks(
1827                                      rdev, sh->sector, STRIPE_SECTORS, 0)))
1828                                md_error(conf->mddev, rdev);
1829                }
1830        }
1831        rdev_dec_pending(rdev, conf->mddev);
1832        clear_bit(R5_LOCKED, &sh->dev[i].flags);
1833        set_bit(STRIPE_HANDLE, &sh->state);
1834        release_stripe(sh);
1835}
1836
1837static void raid5_end_write_request(struct bio *bi, int error)
1838{
1839        struct stripe_head *sh = bi->bi_private;
1840        struct r5conf *conf = sh->raid_conf;
1841        int disks = sh->disks, i;
1842        struct md_rdev *uninitialized_var(rdev);
1843        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1844        sector_t first_bad;
1845        int bad_sectors;
1846        int replacement = 0;
1847
1848        for (i = 0 ; i < disks; i++) {
1849                if (bi == &sh->dev[i].req) {
1850                        rdev = conf->disks[i].rdev;
1851                        break;
1852                }
1853                if (bi == &sh->dev[i].rreq) {
1854                        rdev = conf->disks[i].replacement;
1855                        if (rdev)
1856                                replacement = 1;
1857                        else
1858                                /* rdev was removed and 'replacement'
1859                                 * replaced it.  rdev is not removed
1860                                 * until all requests are finished.
1861                                 */
1862                                rdev = conf->disks[i].rdev;
1863                        break;
1864                }
1865        }
1866        pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1867                (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1868                uptodate);
1869        if (i == disks) {
1870                BUG();
1871                return;
1872        }
1873
1874        if (replacement) {
1875                if (!uptodate)
1876                        md_error(conf->mddev, rdev);
1877                else if (is_badblock(rdev, sh->sector,
1878                                     STRIPE_SECTORS,
1879                                     &first_bad, &bad_sectors))
1880                        set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
1881        } else {
1882                if (!uptodate) {
1883                        set_bit(WriteErrorSeen, &rdev->flags);
1884                        set_bit(R5_WriteError, &sh->dev[i].flags);
1885                        if (!test_and_set_bit(WantReplacement, &rdev->flags))
1886                                set_bit(MD_RECOVERY_NEEDED,
1887                                        &rdev->mddev->recovery);
1888                } else if (is_badblock(rdev, sh->sector,
1889                                       STRIPE_SECTORS,
1890                                       &first_bad, &bad_sectors))
1891                        set_bit(R5_MadeGood, &sh->dev[i].flags);
1892        }
1893        rdev_dec_pending(rdev, conf->mddev);
1894
1895        if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
1896                clear_bit(R5_LOCKED, &sh->dev[i].flags);
1897        set_bit(STRIPE_HANDLE, &sh->state);
1898        release_stripe(sh);
1899}
1900
1901static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1902        
1903static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1904{
1905        struct r5dev *dev = &sh->dev[i];
1906
1907        bio_init(&dev->req);
1908        dev->req.bi_io_vec = &dev->vec;
1909        dev->req.bi_vcnt++;
1910        dev->req.bi_max_vecs++;
1911        dev->req.bi_private = sh;
1912        dev->vec.bv_page = dev->page;
1913
1914        bio_init(&dev->rreq);
1915        dev->rreq.bi_io_vec = &dev->rvec;
1916        dev->rreq.bi_vcnt++;
1917        dev->rreq.bi_max_vecs++;
1918        dev->rreq.bi_private = sh;
1919        dev->rvec.bv_page = dev->page;
1920
1921        dev->flags = 0;
1922        dev->sector = compute_blocknr(sh, i, previous);
1923}
1924
1925static void error(struct mddev *mddev, struct md_rdev *rdev)
1926{
1927        char b[BDEVNAME_SIZE];
1928        struct r5conf *conf = mddev->private;
1929        unsigned long flags;
1930        pr_debug("raid456: error called\n");
1931
1932        spin_lock_irqsave(&conf->device_lock, flags);
1933        clear_bit(In_sync, &rdev->flags);
1934        mddev->degraded = calc_degraded(conf);
1935        spin_unlock_irqrestore(&conf->device_lock, flags);
1936        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1937
1938        set_bit(Blocked, &rdev->flags);
1939        set_bit(Faulty, &rdev->flags);
1940        set_bit(MD_CHANGE_DEVS, &mddev->flags);
1941        printk(KERN_ALERT
1942               "md/raid:%s: Disk failure on %s, disabling device.\n"
1943               "md/raid:%s: Operation continuing on %d devices.\n",
1944               mdname(mddev),
1945               bdevname(rdev->bdev, b),
1946               mdname(mddev),
1947               conf->raid_disks - mddev->degraded);
1948}
1949
1950/*
1951 * Input: a 'big' sector number,
1952 * Output: index of the data and parity disk, and the sector # in them.
1953 */
1954static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
1955                                     int previous, int *dd_idx,
1956                                     struct stripe_head *sh)
1957{
1958        sector_t stripe, stripe2;
1959        sector_t chunk_number;
1960        unsigned int chunk_offset;
1961        int pd_idx, qd_idx;
1962        int ddf_layout = 0;
1963        sector_t new_sector;
1964        int algorithm = previous ? conf->prev_algo
1965                                 : conf->algorithm;
1966        int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1967                                         : conf->chunk_sectors;
1968        int raid_disks = previous ? conf->previous_raid_disks
1969                                  : conf->raid_disks;
1970        int data_disks = raid_disks - conf->max_degraded;
1971
1972        /* First compute the information on this sector */
1973
1974        /*
1975         * Compute the chunk number and the sector offset inside the chunk
1976         */
1977        chunk_offset = sector_div(r_sector, sectors_per_chunk);
1978        chunk_number = r_sector;
1979
1980        /*
1981         * Compute the stripe number
1982         */
1983        stripe = chunk_number;
1984        *dd_idx = sector_div(stripe, data_disks);
1985        stripe2 = stripe;
1986        /*
1987         * Select the parity disk based on the user selected algorithm.
1988         */
1989        pd_idx = qd_idx = -1;
1990        switch(conf->level) {
1991        case 4:
1992                pd_idx = data_disks;
1993                break;
1994        case 5:
1995                switch (algorithm) {
1996                case ALGORITHM_LEFT_ASYMMETRIC:
1997                        pd_idx = data_disks - sector_div(stripe2, raid_disks);
1998                        if (*dd_idx >= pd_idx)
1999                                (*dd_idx)++;
2000                        break;
2001                case ALGORITHM_RIGHT_ASYMMETRIC:
2002                        pd_idx = sector_div(stripe2, raid_disks);
2003                        if (*dd_idx >= pd_idx)
2004                                (*dd_idx)++;
2005                        break;
2006                case ALGORITHM_LEFT_SYMMETRIC:
2007                        pd_idx = data_disks - sector_div(stripe2, raid_disks);
2008                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2009                        break;
2010                case ALGORITHM_RIGHT_SYMMETRIC:
2011                        pd_idx = sector_div(stripe2, raid_disks);
2012                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2013                        break;
2014                case ALGORITHM_PARITY_0:
2015                        pd_idx = 0;
2016                        (*dd_idx)++;
2017                        break;
2018                case ALGORITHM_PARITY_N:
2019                        pd_idx = data_disks;
2020                        break;
2021                default:
2022                        BUG();
2023                }
2024                break;
2025        case 6:
2026
2027                switch (algorithm) {
2028                case ALGORITHM_LEFT_ASYMMETRIC:
2029                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2030                        qd_idx = pd_idx + 1;
2031                        if (pd_idx == raid_disks-1) {
2032                                (*dd_idx)++;    /* Q D D D P */
2033                                qd_idx = 0;
2034                        } else if (*dd_idx >= pd_idx)
2035                                (*dd_idx) += 2; /* D D P Q D */
2036                        break;
2037                case ALGORITHM_RIGHT_ASYMMETRIC:
2038                        pd_idx = sector_div(stripe2, raid_disks);
2039                        qd_idx = pd_idx + 1;
2040                        if (pd_idx == raid_disks-1) {
2041                                (*dd_idx)++;    /* Q D D D P */
2042                                qd_idx = 0;
2043                        } else if (*dd_idx >= pd_idx)
2044                                (*dd_idx) += 2; /* D D P Q D */
2045                        break;
2046                case ALGORITHM_LEFT_SYMMETRIC:
2047                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2048                        qd_idx = (pd_idx + 1) % raid_disks;
2049                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2050                        break;
2051                case ALGORITHM_RIGHT_SYMMETRIC:
2052                        pd_idx = sector_div(stripe2, raid_disks);
2053                        qd_idx = (pd_idx + 1) % raid_disks;
2054                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2055                        break;
2056
2057                case ALGORITHM_PARITY_0:
2058                        pd_idx = 0;
2059                        qd_idx = 1;
2060                        (*dd_idx) += 2;
2061                        break;
2062                case ALGORITHM_PARITY_N:
2063                        pd_idx = data_disks;
2064                        qd_idx = data_disks + 1;
2065                        break;
2066
2067                case ALGORITHM_ROTATING_ZERO_RESTART:
2068                        /* Exactly the same as RIGHT_ASYMMETRIC, but or
2069                         * of blocks for computing Q is different.
2070                         */
2071                        pd_idx = sector_div(stripe2, raid_disks);
2072                        qd_idx = pd_idx + 1;
2073                        if (pd_idx == raid_disks-1) {
2074                                (*dd_idx)++;    /* Q D D D P */
2075                                qd_idx = 0;
2076                        } else if (*dd_idx >= pd_idx)
2077                                (*dd_idx) += 2; /* D D P Q D */
2078                        ddf_layout = 1;
2079                        break;
2080
2081                case ALGORITHM_ROTATING_N_RESTART:
2082                        /* Same a left_asymmetric, by first stripe is
2083                         * D D D P Q  rather than
2084                         * Q D D D P
2085                         */
2086                        stripe2 += 1;
2087                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2088                        qd_idx = pd_idx + 1;
2089                        if (pd_idx == raid_disks-1) {
2090                                (*dd_idx)++;    /* Q D D D P */
2091                                qd_idx = 0;
2092                        } else if (*dd_idx >= pd_idx)
2093                                (*dd_idx) += 2; /* D D P Q D */
2094                        ddf_layout = 1;
2095                        break;
2096
2097                case ALGORITHM_ROTATING_N_CONTINUE:
2098                        /* Same as left_symmetric but Q is before P */
2099                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2100                        qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2101                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2102                        ddf_layout = 1;
2103                        break;
2104
2105                case ALGORITHM_LEFT_ASYMMETRIC_6:
2106                        /* RAID5 left_asymmetric, with Q on last device */
2107                        pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2108                        if (*dd_idx >= pd_idx)
2109                                (*dd_idx)++;
2110                        qd_idx = raid_disks - 1;
2111                        break;
2112
2113                case ALGORITHM_RIGHT_ASYMMETRIC_6:
2114                        pd_idx = sector_div(stripe2, raid_disks-1);
2115                        if (*dd_idx >= pd_idx)
2116                                (*dd_idx)++;
2117                        qd_idx = raid_disks - 1;
2118                        break;
2119
2120                case ALGORITHM_LEFT_SYMMETRIC_6:
2121                        pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2122                        *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2123                        qd_idx = raid_disks - 1;
2124                        break;
2125
2126                case ALGORITHM_RIGHT_SYMMETRIC_6:
2127                        pd_idx = sector_div(stripe2, raid_disks-1);
2128                        *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2129                        qd_idx = raid_disks - 1;
2130                        break;
2131
2132                case ALGORITHM_PARITY_0_6:
2133                        pd_idx = 0;
2134                        (*dd_idx)++;
2135                        qd_idx = raid_disks - 1;
2136                        break;
2137
2138                default:
2139                        BUG();
2140                }
2141                break;
2142        }
2143
2144        if (sh) {
2145                sh->pd_idx = pd_idx;
2146                sh->qd_idx = qd_idx;
2147                sh->ddf_layout = ddf_layout;
2148        }
2149        /*
2150         * Finally, compute the new sector number
2151         */
2152        new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2153        return new_sector;
2154}
2155
2156
2157static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2158{
2159        struct r5conf *conf = sh->raid_conf;
2160        int raid_disks = sh->disks;
2161        int data_disks = raid_disks - conf->max_degraded;
2162        sector_t new_sector = sh->sector, check;
2163        int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2164                                         : conf->chunk_sectors;
2165        int algorithm = previous ? conf->prev_algo
2166                                 : conf->algorithm;
2167        sector_t stripe;
2168        int chunk_offset;
2169        sector_t chunk_number;
2170        int dummy1, dd_idx = i;
2171        sector_t r_sector;
2172        struct stripe_head sh2;
2173
2174
2175        chunk_offset = sector_div(new_sector, sectors_per_chunk);
2176        stripe = new_sector;
2177
2178        if (i == sh->pd_idx)
2179                return 0;
2180        switch(conf->level) {
2181        case 4: break;
2182        case 5:
2183                switch (algorithm) {
2184                case ALGORITHM_LEFT_ASYMMETRIC:
2185                case ALGORITHM_RIGHT_ASYMMETRIC:
2186                        if (i > sh->pd_idx)
2187                                i--;
2188                        break;
2189                case ALGORITHM_LEFT_SYMMETRIC:
2190                case ALGORITHM_RIGHT_SYMMETRIC:
2191                        if (i < sh->pd_idx)
2192                                i += raid_disks;
2193                        i -= (sh->pd_idx + 1);
2194                        break;
2195                case ALGORITHM_PARITY_0:
2196                        i -= 1;
2197                        break;
2198                case ALGORITHM_PARITY_N:
2199                        break;
2200                default:
2201                        BUG();
2202                }
2203                break;
2204        case 6:
2205                if (i == sh->qd_idx)
2206                        return 0; /* It is the Q disk */
2207                switch (algorithm) {
2208                case ALGORITHM_LEFT_ASYMMETRIC:
2209                case ALGORITHM_RIGHT_ASYMMETRIC:
2210                case ALGORITHM_ROTATING_ZERO_RESTART:
2211                case ALGORITHM_ROTATING_N_RESTART:
2212                        if (sh->pd_idx == raid_disks-1)
2213                                i--;    /* Q D D D P */
2214                        else if (i > sh->pd_idx)
2215                                i -= 2; /* D D P Q D */
2216                        break;
2217                case ALGORITHM_LEFT_SYMMETRIC:
2218                case ALGORITHM_RIGHT_SYMMETRIC:
2219                        if (sh->pd_idx == raid_disks-1)
2220                                i--; /* Q D D D P */
2221                        else {
2222                                /* D D P Q D */
2223                                if (i < sh->pd_idx)
2224                                        i += raid_disks;
2225                                i -= (sh->pd_idx + 2);
2226                        }
2227                        break;
2228                case ALGORITHM_PARITY_0:
2229                        i -= 2;
2230                        break;
2231                case ALGORITHM_PARITY_N:
2232                        break;
2233                case ALGORITHM_ROTATING_N_CONTINUE:
2234                        /* Like left_symmetric, but P is before Q */
2235                        if (sh->pd_idx == 0)
2236                                i--;    /* P D D D Q */
2237                        else {
2238                                /* D D Q P D */
2239                                if (i < sh->pd_idx)
2240                                        i += raid_disks;
2241                                i -= (sh->pd_idx + 1);
2242                        }
2243                        break;
2244                case ALGORITHM_LEFT_ASYMMETRIC_6:
2245                case ALGORITHM_RIGHT_ASYMMETRIC_6:
2246                        if (i > sh->pd_idx)
2247                                i--;
2248                        break;
2249                case ALGORITHM_LEFT_SYMMETRIC_6:
2250                case ALGORITHM_RIGHT_SYMMETRIC_6:
2251                        if (i < sh->pd_idx)
2252                                i += data_disks + 1;
2253                        i -= (sh->pd_idx + 1);
2254                        break;
2255                case ALGORITHM_PARITY_0_6:
2256                        i -= 1;
2257                        break;
2258                default:
2259                        BUG();
2260                }
2261                break;
2262        }
2263
2264        chunk_number = stripe * data_disks + i;
2265        r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2266
2267        check = raid5_compute_sector(conf, r_sector,
2268                                     previous, &dummy1, &sh2);
2269        if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2270                || sh2.qd_idx != sh->qd_idx) {
2271                printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2272                       mdname(conf->mddev));
2273                return 0;
2274        }
2275        return r_sector;
2276}
2277
2278
2279static void
2280schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2281                         int rcw, int expand)
2282{
2283        int i, pd_idx = sh->pd_idx, disks = sh->disks;
2284        struct r5conf *conf = sh->raid_conf;
2285        int level = conf->level;
2286
2287        if (rcw) {
2288
2289                for (i = disks; i--; ) {
2290                        struct r5dev *dev = &sh->dev[i];
2291
2292                        if (dev->towrite) {
2293                                set_bit(R5_LOCKED, &dev->flags);
2294                                set_bit(R5_Wantdrain, &dev->flags);
2295                                if (!expand)
2296                                        clear_bit(R5_UPTODATE, &dev->flags);
2297                                s->locked++;
2298                        }
2299                }
2300                /* if we are not expanding this is a proper write request, and
2301                 * there will be bios with new data to be drained into the
2302                 * stripe cache
2303                 */
2304                if (!expand) {
2305                        if (!s->locked)
2306                                /* False alarm, nothing to do */
2307                                return;
2308                        sh->reconstruct_state = reconstruct_state_drain_run;
2309                        set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2310                } else
2311                        sh->reconstruct_state = reconstruct_state_run;
2312
2313                set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2314
2315                if (s->locked + conf->max_degraded == disks)
2316                        if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2317                                atomic_inc(&conf->pending_full_writes);
2318        } else {
2319                BUG_ON(level == 6);
2320                BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2321                        test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2322
2323                for (i = disks; i--; ) {
2324                        struct r5dev *dev = &sh->dev[i];
2325                        if (i == pd_idx)
2326                                continue;
2327
2328                        if (dev->towrite &&
2329                            (test_bit(R5_UPTODATE, &dev->flags) ||
2330                             test_bit(R5_Wantcompute, &dev->flags))) {
2331                                set_bit(R5_Wantdrain, &dev->flags);
2332                                set_bit(R5_LOCKED, &dev->flags);
2333                                clear_bit(R5_UPTODATE, &dev->flags);
2334                                s->locked++;
2335                        }
2336                }
2337                if (!s->locked)
2338                        /* False alarm - nothing to do */
2339                        return;
2340                sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2341                set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2342                set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2343                set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2344        }
2345
2346        /* keep the parity disk(s) locked while asynchronous operations
2347         * are in flight
2348         */
2349        set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2350        clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2351        s->locked++;
2352
2353        if (level == 6) {
2354                int qd_idx = sh->qd_idx;
2355                struct r5dev *dev = &sh->dev[qd_idx];
2356
2357                set_bit(R5_LOCKED, &dev->flags);
2358                clear_bit(R5_UPTODATE, &dev->flags);
2359                s->locked++;
2360        }
2361
2362        pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2363                __func__, (unsigned long long)sh->sector,
2364                s->locked, s->ops_request);
2365}
2366
2367/*
2368 * Each stripe/dev can have one or more bion attached.
2369 * toread/towrite point to the first in a chain.
2370 * The bi_next chain must be in order.
2371 */
2372static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2373{
2374        struct bio **bip;
2375        struct r5conf *conf = sh->raid_conf;
2376        int firstwrite=0;
2377
2378        pr_debug("adding bi b#%llu to stripe s#%llu\n",
2379                (unsigned long long)bi->bi_sector,
2380                (unsigned long long)sh->sector);
2381
2382        /*
2383         * If several bio share a stripe. The bio bi_phys_segments acts as a
2384         * reference count to avoid race. The reference count should already be
2385         * increased before this function is called (for example, in
2386         * make_request()), so other bio sharing this stripe will not free the
2387         * stripe. If a stripe is owned by one stripe, the stripe lock will
2388         * protect it.
2389         */
2390        spin_lock_irq(&sh->stripe_lock);
2391        if (forwrite) {
2392                bip = &sh->dev[dd_idx].towrite;
2393                if (*bip == NULL)
2394                        firstwrite = 1;
2395        } else
2396                bip = &sh->dev[dd_idx].toread;
2397        while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2398                if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
2399                        goto overlap;
2400                bip = & (*bip)->bi_next;
2401        }
2402        if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
2403                goto overlap;
2404
2405        BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2406        if (*bip)
2407                bi->bi_next = *bip;
2408        *bip = bi;
2409        raid5_inc_bi_active_stripes(bi);
2410
2411        if (forwrite) {
2412                /* check if page is covered */
2413                sector_t sector = sh->dev[dd_idx].sector;
2414                for (bi=sh->dev[dd_idx].towrite;
2415                     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2416                             bi && bi->bi_sector <= sector;
2417                     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2418                        if (bi->bi_sector + (bi->bi_size>>9) >= sector)
2419                                sector = bi->bi_sector + (bi->bi_size>>9);
2420                }
2421                if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2422                        set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2423        }
2424
2425        pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2426                (unsigned long long)(*bip)->bi_sector,
2427                (unsigned long long)sh->sector, dd_idx);
2428        spin_unlock_irq(&sh->stripe_lock);
2429
2430        if (conf->mddev->bitmap && firstwrite) {
2431                bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2432                                  STRIPE_SECTORS, 0);
2433                sh->bm_seq = conf->seq_flush+1;
2434                set_bit(STRIPE_BIT_DELAY, &sh->state);
2435        }
2436        return 1;
2437
2438 overlap:
2439        set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2440        spin_unlock_irq(&sh->stripe_lock);
2441        return 0;
2442}
2443
2444static void end_reshape(struct r5conf *conf);
2445
2446static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2447                            struct stripe_head *sh)
2448{
2449        int sectors_per_chunk =
2450                previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2451        int dd_idx;
2452        int chunk_offset = sector_div(stripe, sectors_per_chunk);
2453        int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2454
2455        raid5_compute_sector(conf,
2456                             stripe * (disks - conf->max_degraded)
2457                             *sectors_per_chunk + chunk_offset,
2458                             previous,
2459                             &dd_idx, sh);
2460}
2461
2462static void
2463handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2464                                struct stripe_head_state *s, int disks,
2465                                struct bio **return_bi)
2466{
2467        int i;
2468        for (i = disks; i--; ) {
2469                struct bio *bi;
2470                int bitmap_end = 0;
2471
2472                if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2473                        struct md_rdev *rdev;
2474                        rcu_read_lock();
2475                        rdev = rcu_dereference(conf->disks[i].rdev);
2476                        if (rdev && test_bit(In_sync, &rdev->flags))
2477                                atomic_inc(&rdev->nr_pending);
2478                        else
2479                                rdev = NULL;
2480                        rcu_read_unlock();
2481                        if (rdev) {
2482                                if (!rdev_set_badblocks(
2483                                            rdev,
2484                                            sh->sector,
2485                                            STRIPE_SECTORS, 0))
2486                                        md_error(conf->mddev, rdev);
2487                                rdev_dec_pending(rdev, conf->mddev);
2488                        }
2489                }
2490                spin_lock_irq(&sh->stripe_lock);
2491                /* fail all writes first */
2492                bi = sh->dev[i].towrite;
2493                sh->dev[i].towrite = NULL;
2494                spin_unlock_irq(&sh->stripe_lock);
2495                if (bi)
2496                        bitmap_end = 1;
2497
2498                if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2499                        wake_up(&conf->wait_for_overlap);
2500
2501                while (bi && bi->bi_sector <
2502                        sh->dev[i].sector + STRIPE_SECTORS) {
2503                        struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2504                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
2505                        if (!raid5_dec_bi_active_stripes(bi)) {
2506                                md_write_end(conf->mddev);
2507                                bi->bi_next = *return_bi;
2508                                *return_bi = bi;
2509                        }
2510                        bi = nextbi;
2511                }
2512                if (bitmap_end)
2513                        bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2514                                STRIPE_SECTORS, 0, 0);
2515                bitmap_end = 0;
2516                /* and fail all 'written' */
2517                bi = sh->dev[i].written;
2518                sh->dev[i].written = NULL;
2519                if (bi) bitmap_end = 1;
2520                while (bi && bi->bi_sector <
2521                       sh->dev[i].sector + STRIPE_SECTORS) {
2522                        struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2523                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
2524                        if (!raid5_dec_bi_active_stripes(bi)) {
2525                                md_write_end(conf->mddev);
2526                                bi->bi_next = *return_bi;
2527                                *return_bi = bi;
2528                        }
2529                        bi = bi2;
2530                }
2531
2532                /* fail any reads if this device is non-operational and
2533                 * the data has not reached the cache yet.
2534                 */
2535                if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2536                    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2537                      test_bit(R5_ReadError, &sh->dev[i].flags))) {
2538                        spin_lock_irq(&sh->stripe_lock);
2539                        bi = sh->dev[i].toread;
2540                        sh->dev[i].toread = NULL;
2541                        spin_unlock_irq(&sh->stripe_lock);
2542                        if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2543                                wake_up(&conf->wait_for_overlap);
2544                        while (bi && bi->bi_sector <
2545                               sh->dev[i].sector + STRIPE_SECTORS) {
2546                                struct bio *nextbi =
2547                                        r5_next_bio(bi, sh->dev[i].sector);
2548                                clear_bit(BIO_UPTODATE, &bi->bi_flags);
2549                                if (!raid5_dec_bi_active_stripes(bi)) {
2550                                        bi->bi_next = *return_bi;
2551                                        *return_bi = bi;
2552                                }
2553                                bi = nextbi;
2554                        }
2555                }
2556                if (bitmap_end)
2557                        bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2558                                        STRIPE_SECTORS, 0, 0);
2559                /* If we were in the middle of a write the parity block might
2560                 * still be locked - so just clear all R5_LOCKED flags
2561                 */
2562                clear_bit(R5_LOCKED, &sh->dev[i].flags);
2563        }
2564
2565        if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2566                if (atomic_dec_and_test(&conf->pending_full_writes))
2567                        md_wakeup_thread(conf->mddev->thread);
2568}
2569
2570static void
2571handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2572                   struct stripe_head_state *s)
2573{
2574        int abort = 0;
2575        int i;
2576
2577        clear_bit(STRIPE_SYNCING, &sh->state);
2578        if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
2579                wake_up(&conf->wait_for_overlap);
2580        s->syncing = 0;
2581        s->replacing = 0;
2582        /* There is nothing more to do for sync/check/repair.
2583         * Don't even need to abort as that is handled elsewhere
2584         * if needed, and not always wanted e.g. if there is a known
2585         * bad block here.
2586         * For recover/replace we need to record a bad block on all
2587         * non-sync devices, or abort the recovery
2588         */
2589        if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2590                /* During recovery devices cannot be removed, so
2591                 * locking and refcounting of rdevs is not needed
2592                 */
2593                for (i = 0; i < conf->raid_disks; i++) {
2594                        struct md_rdev *rdev = conf->disks[i].rdev;
2595                        if (rdev
2596                            && !test_bit(Faulty, &rdev->flags)
2597                            && !test_bit(In_sync, &rdev->flags)
2598                            && !rdev_set_badblocks(rdev, sh->sector,
2599                                                   STRIPE_SECTORS, 0))
2600                                abort = 1;
2601                        rdev = conf->disks[i].replacement;
2602                        if (rdev
2603                            && !test_bit(Faulty, &rdev->flags)
2604                            && !test_bit(In_sync, &rdev->flags)
2605                            && !rdev_set_badblocks(rdev, sh->sector,
2606                                                   STRIPE_SECTORS, 0))
2607                                abort = 1;
2608                }
2609                if (abort)
2610                        conf->recovery_disabled =
2611                                conf->mddev->recovery_disabled;
2612        }
2613        md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2614}
2615
2616static int want_replace(struct stripe_head *sh, int disk_idx)
2617{
2618        struct md_rdev *rdev;
2619        int rv = 0;
2620        /* Doing recovery so rcu locking not required */
2621        rdev = sh->raid_conf->disks[disk_idx].replacement;
2622        if (rdev
2623            && !test_bit(Faulty, &rdev->flags)
2624            && !test_bit(In_sync, &rdev->flags)
2625            && (rdev->recovery_offset <= sh->sector
2626                || rdev->mddev->recovery_cp <= sh->sector))
2627                rv = 1;
2628
2629        return rv;
2630}
2631
2632/* fetch_block - checks the given member device to see if its data needs
2633 * to be read or computed to satisfy a request.
2634 *
2635 * Returns 1 when no more member devices need to be checked, otherwise returns
2636 * 0 to tell the loop in handle_stripe_fill to continue
2637 */
2638static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2639                       int disk_idx, int disks)
2640{
2641        struct r5dev *dev = &sh->dev[disk_idx];
2642        struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2643                                  &sh->dev[s->failed_num[1]] };
2644
2645        /* is the data in this block needed, and can we get it? */
2646        if (!test_bit(R5_LOCKED, &dev->flags) &&
2647            !test_bit(R5_UPTODATE, &dev->flags) &&
2648            (dev->toread ||
2649             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2650             s->syncing || s->expanding ||
2651             (s->replacing && want_replace(sh, disk_idx)) ||
2652             (s->failed >= 1 && fdev[0]->toread) ||
2653             (s->failed >= 2 && fdev[1]->toread) ||
2654             (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2655              !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2656             (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
2657                /* we would like to get this block, possibly by computing it,
2658                 * otherwise read it if the backing disk is insync
2659                 */
2660                BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2661                BUG_ON(test_bit(R5_Wantread, &dev->flags));
2662                if ((s->uptodate == disks - 1) &&
2663                    (s->failed && (disk_idx == s->failed_num[0] ||
2664                                   disk_idx == s->failed_num[1]))) {
2665                        /* have disk failed, and we're requested to fetch it;
2666                         * do compute it
2667                         */
2668                        pr_debug("Computing stripe %llu block %d\n",
2669                               (unsigned long long)sh->sector, disk_idx);
2670                        set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2671                        set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2672                        set_bit(R5_Wantcompute, &dev->flags);
2673                        sh->ops.target = disk_idx;
2674                        sh->ops.target2 = -1; /* no 2nd target */
2675                        s->req_compute = 1;
2676                        /* Careful: from this point on 'uptodate' is in the eye
2677                         * of raid_run_ops which services 'compute' operations
2678                         * before writes. R5_Wantcompute flags a block that will
2679                         * be R5_UPTODATE by the time it is needed for a
2680                         * subsequent operation.
2681                         */
2682                        s->uptodate++;
2683                        return 1;
2684                } else if (s->uptodate == disks-2 && s->failed >= 2) {
2685                        /* Computing 2-failure is *very* expensive; only
2686                         * do it if failed >= 2
2687                         */
2688                        int other;
2689                        for (other = disks; other--; ) {
2690                                if (other == disk_idx)
2691                                        continue;
2692                                if (!test_bit(R5_UPTODATE,
2693                                      &sh->dev[other].flags))
2694                                        break;
2695                        }
2696                        BUG_ON(other < 0);
2697                        pr_debug("Computing stripe %llu blocks %d,%d\n",
2698                               (unsigned long long)sh->sector,
2699                               disk_idx, other);
2700                        set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2701                        set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2702                        set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2703                        set_bit(R5_Wantcompute, &sh->dev[other].flags);
2704                        sh->ops.target = disk_idx;
2705                        sh->ops.target2 = other;
2706                        s->uptodate += 2;
2707                        s->req_compute = 1;
2708                        return 1;
2709                } else if (test_bit(R5_Insync, &dev->flags)) {
2710                        set_bit(R5_LOCKED, &dev->flags);
2711                        set_bit(R5_Wantread, &dev->flags);
2712                        s->locked++;
2713                        pr_debug("Reading block %d (sync=%d)\n",
2714                                disk_idx, s->syncing);
2715                }
2716        }
2717
2718        return 0;
2719}
2720
2721/**
2722 * handle_stripe_fill - read or compute data to satisfy pending requests.
2723 */
2724static void handle_stripe_fill(struct stripe_head *sh,
2725                               struct stripe_head_state *s,
2726                               int disks)
2727{
2728        int i;
2729
2730        /* look for blocks to read/compute, skip this if a compute
2731         * is already in flight, or if the stripe contents are in the
2732         * midst of changing due to a write
2733         */
2734        if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2735            !sh->reconstruct_state)
2736                for (i = disks; i--; )
2737                        if (fetch_block(sh, s, i, disks))
2738                                break;
2739        set_bit(STRIPE_HANDLE, &sh->state);
2740}
2741
2742
2743/* handle_stripe_clean_event
2744 * any written block on an uptodate or failed drive can be returned.
2745 * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2746 * never LOCKED, so we don't need to test 'failed' directly.
2747 */
2748static void handle_stripe_clean_event(struct r5conf *conf,
2749        struct stripe_head *sh, int disks, struct bio **return_bi)
2750{
2751        int i;
2752        struct r5dev *dev;
2753        int discard_pending = 0;
2754
2755        for (i = disks; i--; )
2756                if (sh->dev[i].written) {
2757                        dev = &sh->dev[i];
2758                        if (!test_bit(R5_LOCKED, &dev->flags) &&
2759                            (test_bit(R5_UPTODATE, &dev->flags) ||
2760                             test_bit(R5_Discard, &dev->flags))) {
2761                                /* We can return any write requests */
2762                                struct bio *wbi, *wbi2;
2763                                pr_debug("Return write for disc %d\n", i);
2764                                if (test_and_clear_bit(R5_Discard, &dev->flags))
2765                                        clear_bit(R5_UPTODATE, &dev->flags);
2766                                wbi = dev->written;
2767                                dev->written = NULL;
2768                                while (wbi && wbi->bi_sector <
2769                                        dev->sector + STRIPE_SECTORS) {
2770                                        wbi2 = r5_next_bio(wbi, dev->sector);
2771                                        if (!raid5_dec_bi_active_stripes(wbi)) {
2772                                                md_write_end(conf->mddev);
2773                                                wbi->bi_next = *return_bi;
2774                                                *return_bi = wbi;
2775                                        }
2776                                        wbi = wbi2;
2777                                }
2778                                bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2779                                                STRIPE_SECTORS,
2780                                         !test_bit(STRIPE_DEGRADED, &sh->state),
2781                                                0);
2782                        } else if (test_bit(R5_Discard, &dev->flags))
2783                                discard_pending = 1;
2784                }
2785        if (!discard_pending &&
2786            test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
2787                clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
2788                clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2789                if (sh->qd_idx >= 0) {
2790                        clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
2791                        clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
2792                }
2793                /* now that discard is done we can proceed with any sync */
2794                clear_bit(STRIPE_DISCARD, &sh->state);
2795                if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
2796                        set_bit(STRIPE_HANDLE, &sh->state);
2797
2798        }
2799
2800        if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2801                if (atomic_dec_and_test(&conf->pending_full_writes))
2802                        md_wakeup_thread(conf->mddev->thread);
2803}
2804
2805static void handle_stripe_dirtying(struct r5conf *conf,
2806                                   struct stripe_head *sh,
2807                                   struct stripe_head_state *s,
2808                                   int disks)
2809{
2810        int rmw = 0, rcw = 0, i;
2811        sector_t recovery_cp = conf->mddev->recovery_cp;
2812
2813        /* RAID6 requires 'rcw' in current implementation.
2814         * Otherwise, check whether resync is now happening or should start.
2815         * If yes, then the array is dirty (after unclean shutdown or
2816         * initial creation), so parity in some stripes might be inconsistent.
2817         * In this case, we need to always do reconstruct-write, to ensure
2818         * that in case of drive failure or read-error correction, we
2819         * generate correct data from the parity.
2820         */
2821        if (conf->max_degraded == 2 ||
2822            (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
2823                /* Calculate the real rcw later - for now make it
2824                 * look like rcw is cheaper
2825                 */
2826                rcw = 1; rmw = 2;
2827                pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
2828                         conf->max_degraded, (unsigned long long)recovery_cp,
2829                         (unsigned long long)sh->sector);
2830        } else for (i = disks; i--; ) {
2831                /* would I have to read this buffer for read_modify_write */
2832                struct r5dev *dev = &sh->dev[i];
2833                if ((dev->towrite || i == sh->pd_idx) &&
2834                    !test_bit(R5_LOCKED, &dev->flags) &&
2835                    !(test_bit(R5_UPTODATE, &dev->flags) ||
2836                      test_bit(R5_Wantcompute, &dev->flags))) {
2837                        if (test_bit(R5_Insync, &dev->flags))
2838                                rmw++;
2839                        else
2840                                rmw += 2*disks;  /* cannot read it */
2841                }
2842                /* Would I have to read this buffer for reconstruct_write */
2843                if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2844                    !test_bit(R5_LOCKED, &dev->flags) &&
2845                    !(test_bit(R5_UPTODATE, &dev->flags) ||
2846                    test_bit(R5_Wantcompute, &dev->flags))) {
2847                        if (test_bit(R5_Insync, &dev->flags)) rcw++;
2848                        else
2849                                rcw += 2*disks;
2850                }
2851        }
2852        pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2853                (unsigned long long)sh->sector, rmw, rcw);
2854        set_bit(STRIPE_HANDLE, &sh->state);
2855        if (rmw < rcw && rmw > 0) {
2856                /* prefer read-modify-write, but need to get some data */
2857                if (conf->mddev->queue)
2858                        blk_add_trace_msg(conf->mddev->queue,
2859                                          "raid5 rmw %llu %d",
2860                                          (unsigned long long)sh->sector, rmw);
2861                for (i = disks; i--; ) {
2862                        struct r5dev *dev = &sh->dev[i];
2863                        if ((dev->towrite || i == sh->pd_idx) &&
2864                            !test_bit(R5_LOCKED, &dev->flags) &&
2865                            !(test_bit(R5_UPTODATE, &dev->flags) ||
2866                            test_bit(R5_Wantcompute, &dev->flags)) &&
2867                            test_bit(R5_Insync, &dev->flags)) {
2868                                if (
2869                                  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2870                                        pr_debug("Read_old block "
2871                                                 "%d for r-m-w\n", i);
2872                                        set_bit(R5_LOCKED, &dev->flags);
2873                                        set_bit(R5_Wantread, &dev->flags);
2874                                        s->locked++;
2875                                } else {
2876                                        set_bit(STRIPE_DELAYED, &sh->state);
2877                                        set_bit(STRIPE_HANDLE, &sh->state);
2878                                }
2879                        }
2880                }
2881        }
2882        if (rcw <= rmw && rcw > 0) {
2883                /* want reconstruct write, but need to get some data */
2884                int qread =0;
2885                rcw = 0;
2886                for (i = disks; i--; ) {
2887                        struct r5dev *dev = &sh->dev[i];
2888                        if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2889                            i != sh->pd_idx && i != sh->qd_idx &&
2890                            !test_bit(R5_LOCKED, &dev->flags) &&
2891                            !(test_bit(R5_UPTODATE, &dev->flags) ||
2892                              test_bit(R5_Wantcompute, &dev->flags))) {
2893                                rcw++;
2894                                if (!test_bit(R5_Insync, &dev->flags))
2895                                        continue; /* it's a failed drive */
2896                                if (
2897                                  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2898                                        pr_debug("Read_old block "
2899                                                "%d for Reconstruct\n", i);
2900                                        set_bit(R5_LOCKED, &dev->flags);
2901                                        set_bit(R5_Wantread, &dev->flags);
2902                                        s->locked++;
2903                                        qread++;
2904                                } else {
2905                                        set_bit(STRIPE_DELAYED, &sh->state);
2906                                        set_bit(STRIPE_HANDLE, &sh->state);
2907                                }
2908                        }
2909                }
2910                if (rcw && conf->mddev->queue)
2911                        blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
2912                                          (unsigned long long)sh->sector,
2913                                          rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
2914        }
2915        /* now if nothing is locked, and if we have enough data,
2916         * we can start a write request
2917         */
2918        /* since handle_stripe can be called at any time we need to handle the
2919         * case where a compute block operation has been submitted and then a
2920         * subsequent call wants to start a write request.  raid_run_ops only
2921         * handles the case where compute block and reconstruct are requested
2922         * simultaneously.  If this is not the case then new writes need to be
2923         * held off until the compute completes.
2924         */
2925        if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2926            (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2927            !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2928                schedule_reconstruction(sh, s, rcw == 0, 0);
2929}
2930
2931static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
2932                                struct stripe_head_state *s, int disks)
2933{
2934        struct r5dev *dev = NULL;
2935
2936        set_bit(STRIPE_HANDLE, &sh->state);
2937
2938        switch (sh->check_state) {
2939        case check_state_idle:
2940                /* start a new check operation if there are no failures */
2941                if (s->failed == 0) {
2942                        BUG_ON(s->uptodate != disks);
2943                        sh->check_state = check_state_run;
2944                        set_bit(STRIPE_OP_CHECK, &s->ops_request);
2945                        clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2946                        s->uptodate--;
2947                        break;
2948                }
2949                dev = &sh->dev[s->failed_num[0]];
2950                /* fall through */
2951        case check_state_compute_result:
2952                sh->check_state = check_state_idle;
2953                if (!dev)
2954                        dev = &sh->dev[sh->pd_idx];
2955
2956                /* check that a write has not made the stripe insync */
2957                if (test_bit(STRIPE_INSYNC, &sh->state))
2958                        break;
2959
2960                /* either failed parity check, or recovery is happening */
2961                BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2962                BUG_ON(s->uptodate != disks);
2963
2964                set_bit(R5_LOCKED, &dev->flags);
2965                s->locked++;
2966                set_bit(R5_Wantwrite, &dev->flags);
2967
2968                clear_bit(STRIPE_DEGRADED, &sh->state);
2969                set_bit(STRIPE_INSYNC, &sh->state);
2970                break;
2971        case check_state_run:
2972                break; /* we will be called again upon completion */
2973        case check_state_check_result:
2974                sh->check_state = check_state_idle;
2975
2976                /* if a failure occurred during the check operation, leave
2977                 * STRIPE_INSYNC not set and let the stripe be handled again
2978                 */
2979                if (s->failed)
2980                        break;
2981
2982                /* handle a successful check operation, if parity is correct
2983                 * we are done.  Otherwise update the mismatch count and repair
2984                 * parity if !MD_RECOVERY_CHECK
2985                 */
2986                if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
2987                        /* parity is correct (on disc,
2988                         * not in buffer any more)
2989                         */
2990                        set_bit(STRIPE_INSYNC, &sh->state);
2991                else {
2992                        atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
2993                        if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2994                                /* don't try to repair!! */
2995                                set_bit(STRIPE_INSYNC, &sh->state);
2996                        else {
2997                                sh->check_state = check_state_compute_run;
2998                                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2999                                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3000                                set_bit(R5_Wantcompute,
3001                                        &sh->dev[sh->pd_idx].flags);
3002                                sh->ops.target = sh->pd_idx;
3003                                sh->ops.target2 = -1;
3004                                s->uptodate++;
3005                        }
3006                }
3007                break;
3008        case check_state_compute_run:
3009                break;
3010        default:
3011                printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3012                       __func__, sh->check_state,
3013                       (unsigned long long) sh->sector);
3014                BUG();
3015        }
3016}
3017
3018
3019static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3020                                  struct stripe_head_state *s,
3021                                  int disks)
3022{
3023        int pd_idx = sh->pd_idx;
3024        int qd_idx = sh->qd_idx;
3025        struct r5dev *dev;
3026
3027        set_bit(STRIPE_HANDLE, &sh->state);
3028
3029        BUG_ON(s->failed > 2);
3030
3031        /* Want to check and possibly repair P and Q.
3032         * However there could be one 'failed' device, in which
3033         * case we can only check one of them, possibly using the
3034         * other to generate missing data
3035         */
3036
3037        switch (sh->check_state) {
3038        case check_state_idle:
3039                /* start a new check operation if there are < 2 failures */
3040                if (s->failed == s->q_failed) {
3041                        /* The only possible failed device holds Q, so it
3042                         * makes sense to check P (If anything else were failed,
3043                         * we would have used P to recreate it).
3044                         */
3045                        sh->check_state = check_state_run;
3046                }
3047                if (!s->q_failed && s->failed < 2) {
3048                        /* Q is not failed, and we didn't use it to generate
3049                         * anything, so it makes sense to check it
3050                         */
3051                        if (sh->check_state == check_state_run)
3052                                sh->check_state = check_state_run_pq;
3053                        else
3054                                sh->check_state = check_state_run_q;
3055                }
3056
3057                /* discard potentially stale zero_sum_result */
3058                sh->ops.zero_sum_result = 0;
3059
3060                if (sh->check_state == check_state_run) {
3061                        /* async_xor_zero_sum destroys the contents of P */
3062                        clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3063                        s->uptodate--;
3064                }
3065                if (sh->check_state >= check_state_run &&
3066                    sh->check_state <= check_state_run_pq) {
3067                        /* async_syndrome_zero_sum preserves P and Q, so
3068                         * no need to mark them !uptodate here
3069                         */
3070                        set_bit(STRIPE_OP_CHECK, &s->ops_request);
3071                        break;
3072                }
3073
3074                /* we have 2-disk failure */
3075                BUG_ON(s->failed != 2);
3076                /* fall through */
3077        case check_state_compute_result:
3078                sh->check_state = check_state_idle;
3079
3080                /* check that a write has not made the stripe insync */
3081                if (test_bit(STRIPE_INSYNC, &sh->state))
3082                        break;
3083
3084                /* now write out any block on a failed drive,
3085                 * or P or Q if they were recomputed
3086                 */
3087                BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3088                if (s->failed == 2) {
3089                        dev = &sh->dev[s->failed_num[1]];
3090                        s->locked++;
3091                        set_bit(R5_LOCKED, &dev->flags);
3092                        set_bit(R5_Wantwrite, &dev->flags);
3093                }
3094                if (s->failed >= 1) {
3095                        dev = &sh->dev[s->failed_num[0]];
3096                        s->locked++;
3097                        set_bit(R5_LOCKED, &dev->flags);
3098                        set_bit(R5_Wantwrite, &dev->flags);
3099                }
3100                if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3101                        dev = &sh->dev[pd_idx];
3102                        s->locked++;
3103                        set_bit(R5_LOCKED, &dev->flags);
3104                        set_bit(R5_Wantwrite, &dev->flags);
3105                }
3106                if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3107                        dev = &sh->dev[qd_idx];
3108                        s->locked++;
3109                        set_bit(R5_LOCKED, &dev->flags);
3110                        set_bit(R5_Wantwrite, &dev->flags);
3111                }
3112                clear_bit(STRIPE_DEGRADED, &sh->state);
3113
3114                set_bit(STRIPE_INSYNC, &sh->state);
3115                break;
3116        case check_state_run:
3117        case check_state_run_q:
3118        case check_state_run_pq:
3119                break; /* we will be called again upon completion */
3120        case check_state_check_result:
3121                sh->check_state = check_state_idle;
3122
3123                /* handle a successful check operation, if parity is correct
3124                 * we are done.  Otherwise update the mismatch count and repair
3125                 * parity if !MD_RECOVERY_CHECK
3126                 */
3127                if (sh->ops.zero_sum_result == 0) {
3128                        /* both parities are correct */
3129                        if (!s->failed)
3130                                set_bit(STRIPE_INSYNC, &sh->state);
3131                        else {
3132                                /* in contrast to the raid5 case we can validate
3133                                 * parity, but still have a failure to write
3134                                 * back
3135                                 */
3136                                sh->check_state = check_state_compute_result;
3137                                /* Returning at this point means that we may go
3138                                 * off and bring p and/or q uptodate again so
3139                                 * we make sure to check zero_sum_result again
3140                                 * to verify if p or q need writeback
3141                                 */
3142                        }
3143                } else {
3144                        atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3145                        if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3146                                /* don't try to repair!! */
3147                                set_bit(STRIPE_INSYNC, &sh->state);
3148                        else {
3149                                int *target = &sh->ops.target;
3150
3151                                sh->ops.target = -1;
3152                                sh->ops.target2 = -1;
3153                                sh->check_state = check_state_compute_run;
3154                                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3155                                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3156                                if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3157                                        set_bit(R5_Wantcompute,
3158                                                &sh->dev[pd_idx].flags);
3159                                        *target = pd_idx;
3160                                        target = &sh->ops.target2;
3161                                        s->uptodate++;
3162                                }
3163                                if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3164                                        set_bit(R5_Wantcompute,
3165                                                &sh->dev[qd_idx].flags);
3166                                        *target = qd_idx;
3167                                        s->uptodate++;
3168                                }
3169                        }
3170                }
3171                break;
3172        case check_state_compute_run:
3173                break;
3174        default:
3175                printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3176                       __func__, sh->check_state,
3177                       (unsigned long long) sh->sector);
3178                BUG();
3179        }
3180}
3181
3182static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3183{
3184        int i;
3185
3186        /* We have read all the blocks in this stripe and now we need to
3187         * copy some of them into a target stripe for expand.
3188         */
3189        struct dma_async_tx_descriptor *tx = NULL;
3190        clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3191        for (i = 0; i < sh->disks; i++)
3192                if (i != sh->pd_idx && i != sh->qd_idx) {
3193                        int dd_idx, j;
3194                        struct stripe_head *sh2;
3195                        struct async_submit_ctl submit;
3196
3197                        sector_t bn = compute_blocknr(sh, i, 1);
3198                        sector_t s = raid5_compute_sector(conf, bn, 0,
3199                                                          &dd_idx, NULL);
3200                        sh2 = get_active_stripe(conf, s, 0, 1, 1);
3201                        if (sh2 == NULL)
3202                                /* so far only the early blocks of this stripe
3203                                 * have been requested.  When later blocks
3204                                 * get requested, we will try again
3205                                 */
3206                                continue;
3207                        if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3208                           test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3209                                /* must have already done this block */
3210                                release_stripe(sh2);
3211                                continue;
3212                        }
3213
3214                        /* place all the copies on one channel */
3215                        init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3216                        tx = async_memcpy(sh2->dev[dd_idx].page,
3217                                          sh->dev[i].page, 0, 0, STRIPE_SIZE,
3218                                          &submit);
3219
3220                        set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3221                        set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3222                        for (j = 0; j < conf->raid_disks; j++)
3223                                if (j != sh2->pd_idx &&
3224                                    j != sh2->qd_idx &&
3225                                    !test_bit(R5_Expanded, &sh2->dev[j].flags))
3226                                        break;
3227                        if (j == conf->raid_disks) {
3228                                set_bit(STRIPE_EXPAND_READY, &sh2->state);
3229                                set_bit(STRIPE_HANDLE, &sh2->state);
3230                        }
3231                        release_stripe(sh2);
3232
3233                }
3234        /* done submitting copies, wait for them to complete */
3235        async_tx_quiesce(&tx);
3236}
3237
3238/*
3239 * handle_stripe - do things to a stripe.
3240 *
3241 * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3242 * state of various bits to see what needs to be done.
3243 * Possible results:
3244 *    return some read requests which now have data
3245 *    return some write requests which are safely on storage
3246 *    schedule a read on some buffers
3247 *    schedule a write of some buffers
3248 *    return confirmation of parity correctness
3249 *
3250 */
3251
3252static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3253{
3254        struct r5conf *conf = sh->raid_conf;
3255        int disks = sh->disks;
3256        struct r5dev *dev;
3257        int i;
3258        int do_recovery = 0;
3259
3260        memset(s, 0, sizeof(*s));
3261
3262        s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3263        s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3264        s->failed_num[0] = -1;
3265        s->failed_num[1] = -1;
3266
3267        /* Now to look around and see what can be done */
3268        rcu_read_lock();
3269        for (i=disks; i--; ) {
3270                struct md_rdev *rdev;
3271                sector_t first_bad;
3272                int bad_sectors;
3273                int is_bad = 0;
3274
3275                dev = &sh->dev[i];
3276
3277                pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3278                         i, dev->flags,
3279                         dev->toread, dev->towrite, dev->written);
3280                /* maybe we can reply to a read
3281                 *
3282                 * new wantfill requests are only permitted while
3283                 * ops_complete_biofill is guaranteed to be inactive
3284                 */
3285                if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3286                    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3287                        set_bit(R5_Wantfill, &dev->flags);
3288
3289                /* now count some things */
3290                if (test_bit(R5_LOCKED, &dev->flags))
3291                        s->locked++;
3292                if (test_bit(R5_UPTODATE, &dev->flags))
3293                        s->uptodate++;
3294                if (test_bit(R5_Wantcompute, &dev->flags)) {
3295                        s->compute++;
3296                        BUG_ON(s->compute > 2);
3297                }
3298
3299                if (test_bit(R5_Wantfill, &dev->flags))
3300                        s->to_fill++;
3301                else if (dev->toread)
3302                        s->to_read++;
3303                if (dev->towrite) {
3304                        s->to_write++;
3305                        if (!test_bit(R5_OVERWRITE, &dev->flags))
3306                                s->non_overwrite++;
3307                }
3308                if (dev->written)
3309                        s->written++;
3310                /* Prefer to use the replacement for reads, but only
3311                 * if it is recovered enough and has no bad blocks.
3312                 */
3313                rdev = rcu_dereference(conf->disks[i].replacement);
3314                if (rdev && !test_bit(Faulty, &rdev->flags) &&
3315                    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3316                    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3317                                 &first_bad, &bad_sectors))
3318                        set_bit(R5_ReadRepl, &dev->flags);
3319                else {
3320                        if (rdev)
3321                                set_bit(R5_NeedReplace, &dev->flags);
3322                        rdev = rcu_dereference(conf->disks[i].rdev);
3323                        clear_bit(R5_ReadRepl, &dev->flags);
3324                }
3325                if (rdev && test_bit(Faulty, &rdev->flags))
3326                        rdev = NULL;
3327                if (rdev) {
3328                        is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3329                                             &first_bad, &bad_sectors);
3330                        if (s->blocked_rdev == NULL
3331                            && (test_bit(Blocked, &rdev->flags)
3332                                || is_bad < 0)) {
3333                                if (is_bad < 0)
3334                                        set_bit(BlockedBadBlocks,
3335                                                &rdev->flags);
3336                                s->blocked_rdev = rdev;
3337                                atomic_inc(&rdev->nr_pending);
3338                        }
3339                }
3340                clear_bit(R5_Insync, &dev->flags);
3341                if (!rdev)
3342                        /* Not in-sync */;
3343                else if (is_bad) {
3344                        /* also not in-sync */
3345                        if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3346                            test_bit(R5_UPTODATE, &dev->flags)) {
3347                                /* treat as in-sync, but with a read error
3348                                 * which we can now try to correct
3349                                 */
3350                                set_bit(R5_Insync, &dev->flags);
3351                                set_bit(R5_ReadError, &dev->flags);
3352                        }
3353                } else if (test_bit(In_sync, &rdev->flags))
3354                        set_bit(R5_Insync, &dev->flags);
3355                else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3356                        /* in sync if before recovery_offset */
3357                        set_bit(R5_Insync, &dev->flags);
3358                else if (test_bit(R5_UPTODATE, &dev->flags) &&
3359                         test_bit(R5_Expanded, &dev->flags))
3360                        /* If we've reshaped into here, we assume it is Insync.
3361                         * We will shortly update recovery_offset to make
3362                         * it official.
3363                         */
3364                        set_bit(R5_Insync, &dev->flags);
3365
3366                if (rdev && test_bit(R5_WriteError, &dev->flags)) {
3367                        /* This flag does not apply to '.replacement'
3368                         * only to .rdev, so make sure to check that*/
3369                        struct md_rdev *rdev2 = rcu_dereference(
3370                                conf->disks[i].rdev);
3371                        if (rdev2 == rdev)
3372                                clear_bit(R5_Insync, &dev->flags);
3373                        if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3374                                s->handle_bad_blocks = 1;
3375                                atomic_inc(&rdev2->nr_pending);
3376                        } else
3377                                clear_bit(R5_WriteError, &dev->flags);
3378                }
3379                if (rdev && test_bit(R5_MadeGood, &dev->flags)) {
3380                        /* This flag does not apply to '.replacement'
3381                         * only to .rdev, so make sure to check that*/
3382                        struct md_rdev *rdev2 = rcu_dereference(
3383                                conf->disks[i].rdev);
3384                        if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3385                                s->handle_bad_blocks = 1;
3386                                atomic_inc(&rdev2->nr_pending);
3387                        } else
3388                                clear_bit(R5_MadeGood, &dev->flags);
3389                }
3390                if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3391                        struct md_rdev *rdev2 = rcu_dereference(
3392                                conf->disks[i].replacement);
3393                        if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3394                                s->handle_bad_blocks = 1;
3395                                atomic_inc(&rdev2->nr_pending);
3396                        } else
3397                                clear_bit(R5_MadeGoodRepl, &dev->flags);
3398                }
3399                if (!test_bit(R5_Insync, &dev->flags)) {
3400                        /* The ReadError flag will just be confusing now */
3401                        clear_bit(R5_ReadError, &dev->flags);
3402                        clear_bit(R5_ReWrite, &dev->flags);
3403                }
3404                if (test_bit(R5_ReadError, &dev->flags))
3405                        clear_bit(R5_Insync, &dev->flags);
3406                if (!test_bit(R5_Insync, &dev->flags)) {
3407                        if (s->failed < 2)
3408                                s->failed_num[s->failed] = i;
3409                        s->failed++;
3410                        if (rdev && !test_bit(Faulty, &rdev->flags))
3411                                do_recovery = 1;
3412                }
3413        }
3414        if (test_bit(STRIPE_SYNCING, &sh->state)) {
3415                /* If there is a failed device being replaced,
3416                 *     we must be recovering.
3417                 * else if we are after recovery_cp, we must be syncing
3418                 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3419                 * else we can only be replacing
3420                 * sync and recovery both need to read all devices, and so
3421                 * use the same flag.
3422                 */
3423                if (do_recovery ||
3424                    sh->sector >= conf->mddev->recovery_cp ||
3425                    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3426                        s->syncing = 1;
3427                else
3428                        s->replacing = 1;
3429        }
3430        rcu_read_unlock();
3431}
3432
3433static void handle_stripe(struct stripe_head *sh)
3434{
3435        struct stripe_head_state s;
3436        struct r5conf *conf = sh->raid_conf;
3437        int i;
3438        int prexor;
3439        int disks = sh->disks;
3440        struct r5dev *pdev, *qdev;
3441
3442        clear_bit(STRIPE_HANDLE, &sh->state);
3443        if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3444                /* already being handled, ensure it gets handled
3445                 * again when current action finishes */
3446                set_bit(STRIPE_HANDLE, &sh->state);
3447                return;
3448        }
3449
3450        if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3451                spin_lock(&sh->stripe_lock);
3452                /* Cannot process 'sync' concurrently with 'discard' */
3453                if (!test_bit(STRIPE_DISCARD, &sh->state) &&
3454                    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3455                        set_bit(STRIPE_SYNCING, &sh->state);
3456                        clear_bit(STRIPE_INSYNC, &sh->state);
3457                }
3458                spin_unlock(&sh->stripe_lock);
3459        }
3460        clear_bit(STRIPE_DELAYED, &sh->state);
3461
3462        pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3463                "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3464               (unsigned long long)sh->sector, sh->state,
3465               atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3466               sh->check_state, sh->reconstruct_state);
3467
3468        analyse_stripe(sh, &s);
3469
3470        if (s.handle_bad_blocks) {
3471                set_bit(STRIPE_HANDLE, &sh->state);
3472                goto finish;
3473        }
3474
3475        if (unlikely(s.blocked_rdev)) {
3476                if (s.syncing || s.expanding || s.expanded ||
3477                    s.replacing || s.to_write || s.written) {
3478                        set_bit(STRIPE_HANDLE, &sh->state);
3479                        goto finish;
3480                }
3481                /* There is nothing for the blocked_rdev to block */
3482                rdev_dec_pending(s.blocked_rdev, conf->mddev);
3483                s.blocked_rdev = NULL;
3484        }
3485
3486        if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3487                set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3488                set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3489        }
3490
3491        pr_debug("locked=%d uptodate=%d to_read=%d"
3492               " to_write=%d failed=%d failed_num=%d,%d\n",
3493               s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3494               s.failed_num[0], s.failed_num[1]);
3495        /* check if the array has lost more than max_degraded devices and,
3496         * if so, some requests might need to be failed.
3497         */
3498        if (s.failed > conf->max_degraded) {
3499                sh->check_state = 0;
3500                sh->reconstruct_state = 0;
3501                if (s.to_read+s.to_write+s.written)
3502                        handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3503                if (s.syncing + s.replacing)
3504                        handle_failed_sync(conf, sh, &s);
3505        }
3506
3507        /* Now we check to see if any write operations have recently
3508         * completed
3509         */
3510        prexor = 0;
3511        if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3512                prexor = 1;
3513        if (sh->reconstruct_state == reconstruct_state_drain_result ||
3514            sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3515                sh->reconstruct_state = reconstruct_state_idle;
3516
3517                /* All the 'written' buffers and the parity block are ready to
3518                 * be written back to disk
3519                 */
3520                BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3521                       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3522                BUG_ON(sh->qd_idx >= 0 &&
3523                       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3524                       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3525                for (i = disks; i--; ) {
3526                        struct r5dev *dev = &sh->dev[i];
3527                        if (test_bit(R5_LOCKED, &dev->flags) &&
3528                                (i == sh->pd_idx || i == sh->qd_idx ||
3529                                 dev->written)) {
3530                                pr_debug("Writing block %d\n", i);
3531                                set_bit(R5_Wantwrite, &dev->flags);
3532                                if (prexor)
3533                                        continue;
3534                                if (!test_bit(R5_Insync, &dev->flags) ||
3535                                    ((i == sh->pd_idx || i == sh->qd_idx)  &&
3536                                     s.failed == 0))
3537                                        set_bit(STRIPE_INSYNC, &sh->state);
3538                        }
3539                }
3540                if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3541                        s.dec_preread_active = 1;
3542        }
3543
3544        /*
3545         * might be able to return some write requests if the parity blocks
3546         * are safe, or on a failed drive
3547         */
3548        pdev = &sh->dev[sh->pd_idx];
3549        s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3550                || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3551        qdev = &sh->dev[sh->qd_idx];
3552        s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3553                || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3554                || conf->level < 6;
3555
3556        if (s.written &&
3557            (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3558                             && !test_bit(R5_LOCKED, &pdev->flags)
3559                             && (test_bit(R5_UPTODATE, &pdev->flags) ||
3560                                 test_bit(R5_Discard, &pdev->flags))))) &&
3561            (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3562                             && !test_bit(R5_LOCKED, &qdev->flags)
3563                             && (test_bit(R5_UPTODATE, &qdev->flags) ||
3564                                 test_bit(R5_Discard, &qdev->flags))))))
3565                handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3566
3567        /* Now we might consider reading some blocks, either to check/generate
3568         * parity, or to satisfy requests
3569         * or to load a block that is being partially written.
3570         */
3571        if (s.to_read || s.non_overwrite
3572            || (conf->level == 6 && s.to_write && s.failed)
3573            || (s.syncing && (s.uptodate + s.compute < disks))
3574            || s.replacing
3575            || s.expanding)
3576                handle_stripe_fill(sh, &s, disks);
3577
3578        /* Now to consider new write requests and what else, if anything
3579         * should be read.  We do not handle new writes when:
3580         * 1/ A 'write' operation (copy+xor) is already in flight.
3581         * 2/ A 'check' operation is in flight, as it may clobber the parity
3582         *    block.
3583         */
3584        if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3585                handle_stripe_dirtying(conf, sh, &s, disks);
3586
3587        /* maybe we need to check and possibly fix the parity for this stripe
3588         * Any reads will already have been scheduled, so we just see if enough
3589         * data is available.  The parity check is held off while parity
3590         * dependent operations are in flight.
3591         */
3592        if (sh->check_state ||
3593            (s.syncing && s.locked == 0 &&
3594             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3595             !test_bit(STRIPE_INSYNC, &sh->state))) {
3596                if (conf->level == 6)
3597                        handle_parity_checks6(conf, sh, &s, disks);
3598                else
3599                        handle_parity_checks5(conf, sh, &s, disks);
3600        }
3601
3602        if (s.replacing && s.locked == 0
3603            && !test_bit(STRIPE_INSYNC, &sh->state)) {
3604                /* Write out to replacement devices where possible */
3605                for (i = 0; i < conf->raid_disks; i++)
3606                        if (test_bit(R5_UPTODATE, &sh->dev[i].flags) &&
3607                            test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3608                                set_bit(R5_WantReplace, &sh->dev[i].flags);
3609                                set_bit(R5_LOCKED, &sh->dev[i].flags);
3610                                s.locked++;
3611                        }
3612                set_bit(STRIPE_INSYNC, &sh->state);
3613        }
3614        if ((s.syncing || s.replacing) && s.locked == 0 &&
3615            test_bit(STRIPE_INSYNC, &sh->state)) {
3616                md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3617                clear_bit(STRIPE_SYNCING, &sh->state);
3618                if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3619                        wake_up(&conf->wait_for_overlap);
3620        }
3621
3622        /* If the failed drives are just a ReadError, then we might need
3623         * to progress the repair/check process
3624         */
3625        if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3626                for (i = 0; i < s.failed; i++) {
3627                        struct r5dev *dev = &sh->dev[s.failed_num[i]];
3628                        if (test_bit(R5_ReadError, &dev->flags)
3629                            && !test_bit(R5_LOCKED, &dev->flags)
3630                            && test_bit(R5_UPTODATE, &dev->flags)
3631                                ) {
3632                                if (!test_bit(R5_ReWrite, &dev->flags)) {
3633                                        set_bit(R5_Wantwrite, &dev->flags);
3634                                        set_bit(R5_ReWrite, &dev->flags);
3635                                        set_bit(R5_LOCKED, &dev->flags);
3636                                        s.locked++;
3637                                } else {
3638                                        /* let's read it back */
3639                                        set_bit(R5_Wantread, &dev->flags);
3640                                        set_bit(R5_LOCKED, &dev->flags);
3641                                        s.locked++;
3642                                }
3643                        }
3644                }
3645
3646
3647        /* Finish reconstruct operations initiated by the expansion process */
3648        if (sh->reconstruct_state == reconstruct_state_result) {
3649                struct stripe_head *sh_src
3650                        = get_active_stripe(conf, sh->sector, 1, 1, 1);
3651                if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3652                        /* sh cannot be written until sh_src has been read.
3653                         * so arrange for sh to be delayed a little
3654                         */
3655                        set_bit(STRIPE_DELAYED, &sh->state);
3656                        set_bit(STRIPE_HANDLE, &sh->state);
3657                        if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3658                                              &sh_src->state))
3659                                atomic_inc(&conf->preread_active_stripes);
3660                        release_stripe(sh_src);
3661                        goto finish;
3662                }
3663                if (sh_src)
3664                        release_stripe(sh_src);
3665
3666                sh->reconstruct_state = reconstruct_state_idle;
3667                clear_bit(STRIPE_EXPANDING, &sh->state);
3668                for (i = conf->raid_disks; i--; ) {
3669                        set_bit(R5_Wantwrite, &sh->dev[i].flags);
3670                        set_bit(R5_LOCKED, &sh->dev[i].flags);
3671                        s.locked++;
3672                }
3673        }
3674
3675        if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3676            !sh->reconstruct_state) {
3677                /* Need to write out all blocks after computing parity */
3678                sh->disks = conf->raid_disks;
3679                stripe_set_idx(sh->sector, conf, 0, sh);
3680                schedule_reconstruction(sh, &s, 1, 1);
3681        } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3682                clear_bit(STRIPE_EXPAND_READY, &sh->state);
3683                atomic_dec(&conf->reshape_stripes);
3684                wake_up(&conf->wait_for_overlap);
3685                md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3686        }
3687
3688        if (s.expanding && s.locked == 0 &&
3689            !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3690                handle_stripe_expansion(conf, sh);
3691
3692finish:
3693        /* wait for this device to become unblocked */
3694        if (unlikely(s.blocked_rdev)) {
3695                if (conf->mddev->external)
3696                        md_wait_for_blocked_rdev(s.blocked_rdev,
3697                                                 conf->mddev);
3698                else
3699                        /* Internal metadata will immediately
3700                         * be written by raid5d, so we don't
3701                         * need to wait here.
3702                         */
3703                        rdev_dec_pending(s.blocked_rdev,
3704                                         conf->mddev);
3705        }
3706
3707        if (s.handle_bad_blocks)
3708                for (i = disks; i--; ) {
3709                        struct md_rdev *rdev;
3710                        struct r5dev *dev = &sh->dev[i];
3711                        if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3712                                /* We own a safe reference to the rdev */
3713                                rdev = conf->disks[i].rdev;
3714                                if (!rdev_set_badblocks(rdev, sh->sector,
3715                                                        STRIPE_SECTORS, 0))
3716                                        md_error(conf->mddev, rdev);
3717                                rdev_dec_pending(rdev, conf->mddev);
3718                        }
3719                        if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3720                                rdev = conf->disks[i].rdev;
3721                                rdev_clear_badblocks(rdev, sh->sector,
3722                                                     STRIPE_SECTORS, 0);
3723                                rdev_dec_pending(rdev, conf->mddev);
3724                        }
3725                        if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
3726                                rdev = conf->disks[i].replacement;
3727                                if (!rdev)
3728                                        /* rdev have been moved down */
3729                                        rdev = conf->disks[i].rdev;
3730                                rdev_clear_badblocks(rdev, sh->sector,
3731                                                     STRIPE_SECTORS, 0);
3732                                rdev_dec_pending(rdev, conf->mddev);
3733                        }
3734                }
3735
3736        if (s.ops_request)
3737                raid_run_ops(sh, s.ops_request);
3738
3739        ops_run_io(sh, &s);
3740
3741        if (s.dec_preread_active) {
3742                /* We delay this until after ops_run_io so that if make_request
3743                 * is waiting on a flush, it won't continue until the writes
3744                 * have actually been submitted.
3745                 */
3746                atomic_dec(&conf->preread_active_stripes);
3747                if (atomic_read(&conf->preread_active_stripes) <
3748                    IO_THRESHOLD)
3749                        md_wakeup_thread(conf->mddev->thread);
3750        }
3751
3752        return_io(s.return_bi);
3753
3754        clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
3755}
3756
3757static void raid5_activate_delayed(struct r5conf *conf)
3758{
3759        if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3760                while (!list_empty(&conf->delayed_list)) {
3761                        struct list_head *l = conf->delayed_list.next;
3762                        struct stripe_head *sh;
3763                        sh = list_entry(l, struct stripe_head, lru);
3764                        list_del_init(l);
3765                        clear_bit(STRIPE_DELAYED, &sh->state);
3766                        if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3767                                atomic_inc(&conf->preread_active_stripes);
3768                        list_add_tail(&sh->lru, &conf->hold_list);
3769                }
3770        }
3771}
3772
3773static void activate_bit_delay(struct r5conf *conf)
3774{
3775        /* device_lock is held */
3776        struct list_head head;
3777        list_add(&head, &conf->bitmap_list);
3778        list_del_init(&conf->bitmap_list);
3779        while (!list_empty(&head)) {
3780                struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3781                list_del_init(&sh->lru);
3782                atomic_inc(&sh->count);
3783                __release_stripe(conf, sh);
3784        }
3785}
3786
3787int md_raid5_congested(struct mddev *mddev, int bits)
3788{
3789        struct r5conf *conf = mddev->private;
3790
3791        /* No difference between reads and writes.  Just check
3792         * how busy the stripe_cache is
3793         */
3794
3795        if (conf->inactive_blocked)
3796                return 1;
3797        if (conf->quiesce)
3798                return 1;
3799        if (list_empty_careful(&conf->inactive_list))
3800                return 1;
3801
3802        return 0;
3803}
3804EXPORT_SYMBOL_GPL(md_raid5_congested);
3805
3806static int raid5_congested(void *data, int bits)
3807{
3808        struct mddev *mddev = data;
3809
3810        return mddev_congested(mddev, bits) ||
3811                md_raid5_congested(mddev, bits);
3812}
3813
3814/* We want read requests to align with chunks where possible,
3815 * but write requests don't need to.
3816 */
3817static int raid5_mergeable_bvec(struct request_queue *q,
3818                                struct bvec_merge_data *bvm,
3819                                struct bio_vec *biovec)
3820{
3821        struct mddev *mddev = q->queuedata;
3822        sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3823        int max;
3824        unsigned int chunk_sectors = mddev->chunk_sectors;
3825        unsigned int bio_sectors = bvm->bi_size >> 9;
3826
3827        if ((bvm->bi_rw & 1) == WRITE)
3828                return biovec->bv_len; /* always allow writes to be mergeable */
3829
3830        if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3831                chunk_sectors = mddev->new_chunk_sectors;
3832        max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3833        if (max < 0) max = 0;
3834        if (max <= biovec->bv_len && bio_sectors == 0)
3835                return biovec->bv_len;
3836        else
3837                return max;
3838}
3839
3840
3841static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
3842{
3843        sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3844        unsigned int chunk_sectors = mddev->chunk_sectors;
3845        unsigned int bio_sectors = bio->bi_size >> 9;
3846
3847        if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3848                chunk_sectors = mddev->new_chunk_sectors;
3849        return  chunk_sectors >=
3850                ((sector & (chunk_sectors - 1)) + bio_sectors);
3851}
3852
3853/*
3854 *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3855 *  later sampled by raid5d.
3856 */
3857static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
3858{
3859        unsigned long flags;
3860
3861        spin_lock_irqsave(&conf->device_lock, flags);
3862
3863        bi->bi_next = conf->retry_read_aligned_list;
3864        conf->retry_read_aligned_list = bi;
3865
3866        spin_unlock_irqrestore(&conf->device_lock, flags);
3867        md_wakeup_thread(conf->mddev->thread);
3868}
3869
3870
3871static struct bio *remove_bio_from_retry(struct r5conf *conf)
3872{
3873        struct bio *bi;
3874
3875        bi = conf->retry_read_aligned;
3876        if (bi) {
3877                conf->retry_read_aligned = NULL;
3878                return bi;
3879        }
3880        bi = conf->retry_read_aligned_list;
3881        if(bi) {
3882                conf->retry_read_aligned_list = bi->bi_next;
3883                bi->bi_next = NULL;
3884                /*
3885                 * this sets the active strip count to 1 and the processed
3886                 * strip count to zero (upper 8 bits)
3887                 */
3888                raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
3889        }
3890
3891        return bi;
3892}
3893
3894
3895/*
3896 *  The "raid5_align_endio" should check if the read succeeded and if it
3897 *  did, call bio_endio on the original bio (having bio_put the new bio
3898 *  first).
3899 *  If the read failed..
3900 */
3901static void raid5_align_endio(struct bio *bi, int error)
3902{
3903        struct bio* raid_bi  = bi->bi_private;
3904        struct mddev *mddev;
3905        struct r5conf *conf;
3906        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3907        struct md_rdev *rdev;
3908
3909        bio_put(bi);
3910
3911        rdev = (void*)raid_bi->bi_next;
3912        raid_bi->bi_next = NULL;
3913        mddev = rdev->mddev;
3914        conf = mddev->private;
3915
3916        rdev_dec_pending(rdev, conf->mddev);
3917
3918        if (!error && uptodate) {
3919                trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
3920                                         raid_bi, 0);
3921                bio_endio(raid_bi, 0);
3922                if (atomic_dec_and_test(&conf->active_aligned_reads))
3923                        wake_up(&conf->wait_for_stripe);
3924                return;
3925        }
3926
3927
3928        pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3929
3930        add_bio_to_retry(raid_bi, conf);
3931}
3932
3933static int bio_fits_rdev(struct bio *bi)
3934{
3935        struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3936
3937        if ((bi->bi_size>>9) > queue_max_sectors(q))
3938                return 0;
3939        blk_recount_segments(q, bi);
3940        if (bi->bi_phys_segments > queue_max_segments(q))
3941                return 0;
3942
3943        if (q->merge_bvec_fn)
3944                /* it's too hard to apply the merge_bvec_fn at this stage,
3945                 * just just give up
3946                 */
3947                return 0;
3948
3949        return 1;
3950}
3951
3952
3953static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
3954{
3955        struct r5conf *conf = mddev->private;
3956        int dd_idx;
3957        struct bio* align_bi;
3958        struct md_rdev *rdev;
3959        sector_t end_sector;
3960
3961        if (!in_chunk_boundary(mddev, raid_bio)) {
3962                pr_debug("chunk_aligned_read : non aligned\n");
3963                return 0;
3964        }
3965        /*
3966         * use bio_clone_mddev to make a copy of the bio
3967         */
3968        align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
3969        if (!align_bi)
3970                return 0;
3971        /*
3972         *   set bi_end_io to a new function, and set bi_private to the
3973         *     original bio.
3974         */
3975        align_bi->bi_end_io  = raid5_align_endio;
3976        align_bi->bi_private = raid_bio;
3977        /*
3978         *      compute position
3979         */
3980        align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
3981                                                    0,
3982                                                    &dd_idx, NULL);
3983
3984        end_sector = align_bi->bi_sector + (align_bi->bi_size >> 9);
3985        rcu_read_lock();
3986        rdev = rcu_dereference(conf->disks[dd_idx].replacement);
3987        if (!rdev || test_bit(Faulty, &rdev->flags) ||
3988            rdev->recovery_offset < end_sector) {
3989                rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3990                if (rdev &&
3991                    (test_bit(Faulty, &rdev->flags) ||
3992                    !(test_bit(In_sync, &rdev->flags) ||
3993                      rdev->recovery_offset >= end_sector)))
3994                        rdev = NULL;
3995        }
3996        if (rdev) {
3997                sector_t first_bad;
3998                int bad_sectors;
3999
4000                atomic_inc(&rdev->nr_pending);
4001                rcu_read_unlock();
4002                raid_bio->bi_next = (void*)rdev;
4003                align_bi->bi_bdev =  rdev->bdev;
4004                align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
4005
4006                if (!bio_fits_rdev(align_bi) ||
4007                    is_badblock(rdev, align_bi->bi_sector, align_bi->bi_size>>9,
4008                                &first_bad, &bad_sectors)) {
4009                        /* too big in some way, or has a known bad block */
4010                        bio_put(align_bi);
4011                        rdev_dec_pending(rdev, mddev);
4012                        return 0;
4013                }
4014
4015                /* No reshape active, so we can trust rdev->data_offset */
4016                align_bi->bi_sector += rdev->data_offset;
4017
4018                spin_lock_irq(&conf->device_lock);
4019                wait_event_lock_irq(conf->wait_for_stripe,
4020                                    conf->quiesce == 0,
4021                                    conf->device_lock);
4022                atomic_inc(&conf->active_aligned_reads);
4023                spin_unlock_irq(&conf->device_lock);
4024
4025                if (mddev->gendisk)
4026                        trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4027                                              align_bi, disk_devt(mddev->gendisk),
4028                                              raid_bio->bi_sector);
4029                generic_make_request(align_bi);
4030                return 1;
4031        } else {
4032                rcu_read_unlock();
4033                bio_put(align_bi);
4034                return 0;
4035        }
4036}
4037
4038/* __get_priority_stripe - get the next stripe to process
4039 *
4040 * Full stripe writes are allowed to pass preread active stripes up until
4041 * the bypass_threshold is exceeded.  In general the bypass_count
4042 * increments when the handle_list is handled before the hold_list; however, it
4043 * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4044 * stripe with in flight i/o.  The bypass_count will be reset when the
4045 * head of the hold_list has changed, i.e. the head was promoted to the
4046 * handle_list.
4047 */
4048static struct stripe_head *__get_priority_stripe(struct r5conf *conf)
4049{
4050        struct stripe_head *sh;
4051
4052        pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4053                  __func__,
4054                  list_empty(&conf->handle_list) ? "empty" : "busy",
4055                  list_empty(&conf->hold_list) ? "empty" : "busy",
4056                  atomic_read(&conf->pending_full_writes), conf->bypass_count);
4057
4058        if (!list_empty(&conf->handle_list)) {
4059                sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
4060
4061                if (list_empty(&conf->hold_list))
4062                        conf->bypass_count = 0;
4063                else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4064                        if (conf->hold_list.next == conf->last_hold)
4065                                conf->bypass_count++;
4066                        else {
4067                                conf->last_hold = conf->hold_list.next;
4068                                conf->bypass_count -= conf->bypass_threshold;
4069                                if (conf->bypass_count < 0)
4070                                        conf->bypass_count = 0;
4071                        }
4072                }
4073        } else if (!list_empty(&conf->hold_list) &&
4074                   ((conf->bypass_threshold &&
4075                     conf->bypass_count > conf->bypass_threshold) ||
4076                    atomic_read(&conf->pending_full_writes) == 0)) {
4077                sh = list_entry(conf->hold_list.next,
4078                                typeof(*sh), lru);
4079                conf->bypass_count -= conf->bypass_threshold;
4080                if (conf->bypass_count < 0)
4081                        conf->bypass_count = 0;
4082        } else
4083                return NULL;
4084
4085        list_del_init(&sh->lru);
4086        atomic_inc(&sh->count);
4087        BUG_ON(atomic_read(&sh->count) != 1);
4088        return sh;
4089}
4090
4091struct raid5_plug_cb {
4092        struct blk_plug_cb      cb;
4093        struct list_head        list;
4094};
4095
4096static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4097{
4098        struct raid5_plug_cb *cb = container_of(
4099                blk_cb, struct raid5_plug_cb, cb);
4100        struct stripe_head *sh;
4101        struct mddev *mddev = cb->cb.data;
4102        struct r5conf *conf = mddev->private;
4103        int cnt = 0;
4104
4105        if (cb->list.next && !list_empty(&cb->list)) {
4106                spin_lock_irq(&conf->device_lock);
4107                while (!list_empty(&cb->list)) {
4108                        sh = list_first_entry(&cb->list, struct stripe_head, lru);
4109                        list_del_init(&sh->lru);
4110                        /*
4111                         * avoid race release_stripe_plug() sees
4112                         * STRIPE_ON_UNPLUG_LIST clear but the stripe
4113                         * is still in our list
4114                         */
4115                        smp_mb__before_clear_bit();
4116                        clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4117                        __release_stripe(conf, sh);
4118                        cnt++;
4119                }
4120                spin_unlock_irq(&conf->device_lock);
4121        }
4122        if (mddev->queue)
4123                trace_block_unplug(mddev->queue, cnt, !from_schedule);
4124        kfree(cb);
4125}
4126
4127static void release_stripe_plug(struct mddev *mddev,
4128                                struct stripe_head *sh)
4129{
4130        struct blk_plug_cb *blk_cb = blk_check_plugged(
4131                raid5_unplug, mddev,
4132                sizeof(struct raid5_plug_cb));
4133        struct raid5_plug_cb *cb;
4134
4135        if (!blk_cb) {
4136                release_stripe(sh);
4137                return;
4138        }
4139
4140        cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4141
4142        if (cb->list.next == NULL)
4143                INIT_LIST_HEAD(&cb->list);
4144
4145        if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4146                list_add_tail(&sh->lru, &cb->list);
4147        else
4148                release_stripe(sh);
4149}
4150
4151static void make_discard_request(struct mddev *mddev, struct bio *bi)
4152{
4153        struct r5conf *conf = mddev->private;
4154        sector_t logical_sector, last_sector;
4155        struct stripe_head *sh;
4156        int remaining;
4157        int stripe_sectors;
4158
4159        if (mddev->reshape_position != MaxSector)
4160                /* Skip discard while reshape is happening */
4161                return;
4162
4163        logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4164        last_sector = bi->bi_sector + (bi->bi_size>>9);
4165
4166        bi->bi_next = NULL;
4167        bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4168
4169        stripe_sectors = conf->chunk_sectors *
4170                (conf->raid_disks - conf->max_degraded);
4171        logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4172                                               stripe_sectors);
4173        sector_div(last_sector, stripe_sectors);
4174
4175        logical_sector *= conf->chunk_sectors;
4176        last_sector *= conf->chunk_sectors;
4177
4178        for (; logical_sector < last_sector;
4179             logical_sector += STRIPE_SECTORS) {
4180                DEFINE_WAIT(w);
4181                int d;
4182        again:
4183                sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4184                prepare_to_wait(&conf->wait_for_overlap, &w,
4185                                TASK_UNINTERRUPTIBLE);
4186                set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4187                if (test_bit(STRIPE_SYNCING, &sh->state)) {
4188                        release_stripe(sh);
4189                        schedule();
4190                        goto again;
4191                }
4192                clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4193                spin_lock_irq(&sh->stripe_lock);
4194                for (d = 0; d < conf->raid_disks; d++) {
4195                        if (d == sh->pd_idx || d == sh->qd_idx)
4196                                continue;
4197                        if (sh->dev[d].towrite || sh->dev[d].toread) {
4198                                set_bit(R5_Overlap, &sh->dev[d].flags);
4199                                spin_unlock_irq(&sh->stripe_lock);
4200                                release_stripe(sh);
4201                                schedule();
4202                                goto again;
4203                        }
4204                }
4205                set_bit(STRIPE_DISCARD, &sh->state);
4206                finish_wait(&conf->wait_for_overlap, &w);
4207                for (d = 0; d < conf->raid_disks; d++) {
4208                        if (d == sh->pd_idx || d == sh->qd_idx)
4209                                continue;
4210                        sh->dev[d].towrite = bi;
4211                        set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4212                        raid5_inc_bi_active_stripes(bi);
4213                }
4214                spin_unlock_irq(&sh->stripe_lock);
4215                if (conf->mddev->bitmap) {
4216                        for (d = 0;
4217                             d < conf->raid_disks - conf->max_degraded;
4218                             d++)
4219                                bitmap_startwrite(mddev->bitmap,
4220                                                  sh->sector,
4221                                                  STRIPE_SECTORS,
4222                                                  0);
4223                        sh->bm_seq = conf->seq_flush + 1;
4224                        set_bit(STRIPE_BIT_DELAY, &sh->state);
4225                }
4226
4227                set_bit(STRIPE_HANDLE, &sh->state);
4228                clear_bit(STRIPE_DELAYED, &sh->state);
4229                if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4230                        atomic_inc(&conf->preread_active_stripes);
4231                release_stripe_plug(mddev, sh);
4232        }
4233
4234        remaining = raid5_dec_bi_active_stripes(bi);
4235        if (remaining == 0) {
4236                md_write_end(mddev);
4237                bio_endio(bi, 0);
4238        }
4239}
4240
4241static void make_request(struct mddev *mddev, struct bio * bi)
4242{
4243        struct r5conf *conf = mddev->private;
4244        int dd_idx;
4245        sector_t new_sector;
4246        sector_t logical_sector, last_sector;
4247        struct stripe_head *sh;
4248        const int rw = bio_data_dir(bi);
4249        int remaining;
4250
4251        if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4252                md_flush_request(mddev, bi);
4253                return;
4254        }
4255
4256        md_write_start(mddev, bi);
4257
4258        if (rw == READ &&
4259             mddev->reshape_position == MaxSector &&
4260             chunk_aligned_read(mddev,bi))
4261                return;
4262
4263        if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4264                make_discard_request(mddev, bi);
4265                return;
4266        }
4267
4268        logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4269        last_sector = bi->bi_sector + (bi->bi_size>>9);
4270        bi->bi_next = NULL;
4271        bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
4272
4273        for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4274                DEFINE_WAIT(w);
4275                int previous;
4276
4277        retry:
4278                previous = 0;
4279                prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4280                if (unlikely(conf->reshape_progress != MaxSector)) {
4281                        /* spinlock is needed as reshape_progress may be
4282                         * 64bit on a 32bit platform, and so it might be
4283                         * possible to see a half-updated value
4284                         * Of course reshape_progress could change after
4285                         * the lock is dropped, so once we get a reference
4286                         * to the stripe that we think it is, we will have
4287                         * to check again.
4288                         */
4289                        spin_lock_irq(&conf->device_lock);
4290                        if (mddev->reshape_backwards
4291                            ? logical_sector < conf->reshape_progress
4292                            : logical_sector >= conf->reshape_progress) {
4293                                previous = 1;
4294                        } else {
4295                                if (mddev->reshape_backwards
4296                                    ? logical_sector < conf->reshape_safe
4297                                    : logical_sector >= conf->reshape_safe) {
4298                                        spin_unlock_irq(&conf->device_lock);
4299                                        schedule();
4300                                        goto retry;
4301                                }
4302                        }
4303                        spin_unlock_irq(&conf->device_lock);
4304                }
4305
4306                new_sector = raid5_compute_sector(conf, logical_sector,
4307                                                  previous,
4308                                                  &dd_idx, NULL);
4309                pr_debug("raid456: make_request, sector %llu logical %llu\n",
4310                        (unsigned long long)new_sector, 
4311                        (unsigned long long)logical_sector);
4312
4313                sh = get_active_stripe(conf, new_sector, previous,
4314                                       (bi->bi_rw&RWA_MASK), 0);
4315                if (sh) {
4316                        if (unlikely(previous)) {
4317                                /* expansion might have moved on while waiting for a
4318                                 * stripe, so we must do the range check again.
4319                                 * Expansion could still move past after this
4320                                 * test, but as we are holding a reference to
4321                                 * 'sh', we know that if that happens,
4322                                 *  STRIPE_EXPANDING will get set and the expansion
4323                                 * won't proceed until we finish with the stripe.
4324                                 */
4325                                int must_retry = 0;
4326                                spin_lock_irq(&conf->device_lock);
4327                                if (mddev->reshape_backwards
4328                                    ? logical_sector >= conf->reshape_progress
4329                                    : logical_sector < conf->reshape_progress)
4330                                        /* mismatch, need to try again */
4331                                        must_retry = 1;
4332                                spin_unlock_irq(&conf->device_lock);
4333                                if (must_retry) {
4334                                        release_stripe(sh);
4335                                        schedule();
4336                                        goto retry;
4337                                }
4338                        }
4339
4340                        if (rw == WRITE &&
4341                            logical_sector >= mddev->suspend_lo &&
4342                            logical_sector < mddev->suspend_hi) {
4343                                release_stripe(sh);
4344                                /* As the suspend_* range is controlled by
4345                                 * userspace, we want an interruptible
4346                                 * wait.
4347                                 */
4348                                flush_signals(current);
4349                                prepare_to_wait(&conf->wait_for_overlap,
4350                                                &w, TASK_INTERRUPTIBLE);
4351                                if (logical_sector >= mddev->suspend_lo &&
4352                                    logical_sector < mddev->suspend_hi)
4353                                        schedule();
4354                                goto retry;
4355                        }
4356
4357                        if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4358                            !add_stripe_bio(sh, bi, dd_idx, rw)) {
4359                                /* Stripe is busy expanding or
4360                                 * add failed due to overlap.  Flush everything
4361                                 * and wait a while
4362                                 */
4363                                md_wakeup_thread(mddev->thread);
4364                                release_stripe(sh);
4365                                schedule();
4366                                goto retry;
4367                        }
4368                        finish_wait(&conf->wait_for_overlap, &w);
4369                        set_bit(STRIPE_HANDLE, &sh->state);
4370                        clear_bit(STRIPE_DELAYED, &sh->state);
4371                        if ((bi->bi_rw & REQ_SYNC) &&
4372                            !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4373                                atomic_inc(&conf->preread_active_stripes);
4374                        release_stripe_plug(mddev, sh);
4375                } else {
4376                        /* cannot get stripe for read-ahead, just give-up */
4377                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
4378                        finish_wait(&conf->wait_for_overlap, &w);
4379                        break;
4380                }
4381        }
4382
4383        remaining = raid5_dec_bi_active_stripes(bi);
4384        if (remaining == 0) {
4385
4386                if ( rw == WRITE )
4387                        md_write_end(mddev);
4388
4389                trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4390                                         bi, 0);
4391                bio_endio(bi, 0);
4392        }
4393}
4394
4395static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4396
4397static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4398{
4399        /* reshaping is quite different to recovery/resync so it is
4400         * handled quite separately ... here.
4401         *
4402         * On each call to sync_request, we gather one chunk worth of
4403         * destination stripes and flag them as expanding.
4404         * Then we find all the source stripes and request reads.
4405         * As the reads complete, handle_stripe will copy the data
4406         * into the destination stripe and release that stripe.
4407         */
4408        struct r5conf *conf = mddev->private;
4409        struct stripe_head *sh;
4410        sector_t first_sector, last_sector;
4411        int raid_disks = conf->previous_raid_disks;
4412        int data_disks = raid_disks - conf->max_degraded;
4413        int new_data_disks = conf->raid_disks - conf->max_degraded;
4414        int i;
4415        int dd_idx;
4416        sector_t writepos, readpos, safepos;
4417        sector_t stripe_addr;
4418        int reshape_sectors;
4419        struct list_head stripes;
4420
4421        if (sector_nr == 0) {
4422                /* If restarting in the middle, skip the initial sectors */
4423                if (mddev->reshape_backwards &&
4424                    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4425                        sector_nr = raid5_size(mddev, 0, 0)
4426                                - conf->reshape_progress;
4427                } else if (!mddev->reshape_backwards &&
4428                           conf->reshape_progress > 0)
4429                        sector_nr = conf->reshape_progress;
4430                sector_div(sector_nr, new_data_disks);
4431                if (sector_nr) {
4432                        mddev->curr_resync_completed = sector_nr;
4433                        sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4434                        *skipped = 1;
4435                        return sector_nr;
4436                }
4437        }
4438
4439        /* We need to process a full chunk at a time.
4440         * If old and new chunk sizes differ, we need to process the
4441         * largest of these
4442         */
4443        if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4444                reshape_sectors = mddev->new_chunk_sectors;
4445        else
4446                reshape_sectors = mddev->chunk_sectors;
4447
4448        /* We update the metadata at least every 10 seconds, or when
4449         * the data about to be copied would over-write the source of
4450         * the data at the front of the range.  i.e. one new_stripe
4451         * along from reshape_progress new_maps to after where
4452         * reshape_safe old_maps to
4453         */
4454        writepos = conf->reshape_progress;
4455        sector_div(writepos, new_data_disks);
4456        readpos = conf->reshape_progress;
4457        sector_div(readpos, data_disks);
4458        safepos = conf->reshape_safe;
4459        sector_div(safepos, data_disks);
4460        if (mddev->reshape_backwards) {
4461                writepos -= min_t(sector_t, reshape_sectors, writepos);
4462                readpos += reshape_sectors;
4463                safepos += reshape_sectors;
4464        } else {
4465                writepos += reshape_sectors;
4466                readpos -= min_t(sector_t, reshape_sectors, readpos);
4467                safepos -= min_t(sector_t, reshape_sectors, safepos);
4468        }
4469
4470        /* Having calculated the 'writepos' possibly use it
4471         * to set 'stripe_addr' which is where we will write to.
4472         */
4473        if (mddev->reshape_backwards) {
4474                BUG_ON(conf->reshape_progress == 0);
4475                stripe_addr = writepos;
4476                BUG_ON((mddev->dev_sectors &
4477                        ~((sector_t)reshape_sectors - 1))
4478                       - reshape_sectors - stripe_addr
4479                       != sector_nr);
4480        } else {
4481                BUG_ON(writepos != sector_nr + reshape_sectors);
4482                stripe_addr = sector_nr;
4483        }
4484
4485        /* 'writepos' is the most advanced device address we might write.
4486         * 'readpos' is the least advanced device address we might read.
4487         * 'safepos' is the least address recorded in the metadata as having
4488         *     been reshaped.
4489         * If there is a min_offset_diff, these are adjusted either by
4490         * increasing the safepos/readpos if diff is negative, or
4491         * increasing writepos if diff is positive.
4492         * If 'readpos' is then behind 'writepos', there is no way that we can
4493         * ensure safety in the face of a crash - that must be done by userspace
4494         * making a backup of the data.  So in that case there is no particular
4495         * rush to update metadata.
4496         * Otherwise if 'safepos' is behind 'writepos', then we really need to
4497         * update the metadata to advance 'safepos' to match 'readpos' so that
4498         * we can be safe in the event of a crash.
4499         * So we insist on updating metadata if safepos is behind writepos and
4500         * readpos is beyond writepos.
4501         * In any case, update the metadata every 10 seconds.
4502         * Maybe that number should be configurable, but I'm not sure it is
4503         * worth it.... maybe it could be a multiple of safemode_delay???
4504         */
4505        if (conf->min_offset_diff < 0) {
4506                safepos += -conf->min_offset_diff;
4507                readpos += -conf->min_offset_diff;
4508        } else
4509                writepos += conf->min_offset_diff;
4510
4511        if ((mddev->reshape_backwards
4512             ? (safepos > writepos && readpos < writepos)
4513             : (safepos < writepos && readpos > writepos)) ||
4514            time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4515                /* Cannot proceed until we've updated the superblock... */
4516                wait_event(conf->wait_for_overlap,
4517                           atomic_read(&conf->reshape_stripes)==0);
4518                mddev->reshape_position = conf->reshape_progress;
4519                mddev->curr_resync_completed = sector_nr;
4520                conf->reshape_checkpoint = jiffies;
4521                set_bit(MD_CHANGE_DEVS, &mddev->flags);
4522                md_wakeup_thread(mddev->thread);
4523                wait_event(mddev->sb_wait, mddev->flags == 0 ||
4524                           kthread_should_stop());
4525                spin_lock_irq(&conf->device_lock);
4526                conf->reshape_safe = mddev->reshape_position;
4527                spin_unlock_irq(&conf->device_lock);
4528                wake_up(&conf->wait_for_overlap);
4529                sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4530        }
4531
4532        INIT_LIST_HEAD(&stripes);
4533        for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4534                int j;
4535                int skipped_disk = 0;
4536                sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4537                set_bit(STRIPE_EXPANDING, &sh->state);
4538                atomic_inc(&conf->reshape_stripes);
4539                /* If any of this stripe is beyond the end of the old
4540                 * array, then we need to zero those blocks
4541                 */
4542                for (j=sh->disks; j--;) {
4543                        sector_t s;
4544                        if (j == sh->pd_idx)
4545                                continue;
4546                        if (conf->level == 6 &&
4547                            j == sh->qd_idx)
4548                                continue;
4549                        s = compute_blocknr(sh, j, 0);
4550                        if (s < raid5_size(mddev, 0, 0)) {
4551                                skipped_disk = 1;
4552                                continue;
4553                        }
4554                        memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4555                        set_bit(R5_Expanded, &sh->dev[j].flags);
4556                        set_bit(R5_UPTODATE, &sh->dev[j].flags);
4557                }
4558                if (!skipped_disk) {
4559                        set_bit(STRIPE_EXPAND_READY, &sh->state);
4560                        set_bit(STRIPE_HANDLE, &sh->state);
4561                }
4562                list_add(&sh->lru, &stripes);
4563        }
4564        spin_lock_irq(&conf->device_lock);
4565        if (mddev->reshape_backwards)
4566                conf->reshape_progress -= reshape_sectors * new_data_disks;
4567        else
4568                conf->reshape_progress += reshape_sectors * new_data_disks;
4569        spin_unlock_irq(&conf->device_lock);
4570        /* Ok, those stripe are ready. We can start scheduling
4571         * reads on the source stripes.
4572         * The source stripes are determined by mapping the first and last
4573         * block on the destination stripes.
4574         */
4575        first_sector =
4576                raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4577                                     1, &dd_idx, NULL);
4578        last_sector =
4579                raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4580                                            * new_data_disks - 1),
4581                                     1, &dd_idx, NULL);
4582        if (last_sector >= mddev->dev_sectors)
4583                last_sector = mddev->dev_sectors - 1;
4584        while (first_sector <= last_sector) {
4585                sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4586                set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4587                set_bit(STRIPE_HANDLE, &sh->state);
4588                release_stripe(sh);
4589                first_sector += STRIPE_SECTORS;
4590        }
4591        /* Now that the sources are clearly marked, we can release
4592         * the destination stripes
4593         */
4594        while (!list_empty(&stripes)) {
4595                sh = list_entry(stripes.next, struct stripe_head, lru);
4596                list_del_init(&sh->lru);
4597                release_stripe(sh);
4598        }
4599        /* If this takes us to the resync_max point where we have to pause,
4600         * then we need to write out the superblock.
4601         */
4602        sector_nr += reshape_sectors;
4603        if ((sector_nr - mddev->curr_resync_completed) * 2
4604            >= mddev->resync_max - mddev->curr_resync_completed) {
4605                /* Cannot proceed until we've updated the superblock... */
4606                wait_event(conf->wait_for_overlap,
4607                           atomic_read(&conf->reshape_stripes) == 0);
4608                mddev->reshape_position = conf->reshape_progress;
4609                mddev->curr_resync_completed = sector_nr;
4610                conf->reshape_checkpoint = jiffies;
4611                set_bit(MD_CHANGE_DEVS, &mddev->flags);
4612                md_wakeup_thread(mddev->thread);
4613                wait_event(mddev->sb_wait,
4614                           !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4615                           || kthread_should_stop());
4616                spin_lock_irq(&conf->device_lock);
4617                conf->reshape_safe = mddev->reshape_position;
4618                spin_unlock_irq(&conf->device_lock);
4619                wake_up(&conf->wait_for_overlap);
4620                sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4621        }
4622        return reshape_sectors;
4623}
4624
4625/* FIXME go_faster isn't used */
4626static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4627{
4628        struct r5conf *conf = mddev->private;
4629        struct stripe_head *sh;
4630        sector_t max_sector = mddev->dev_sectors;
4631        sector_t sync_blocks;
4632        int still_degraded = 0;
4633        int i;
4634
4635        if (sector_nr >= max_sector) {
4636                /* just being told to finish up .. nothing much to do */
4637
4638                if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4639                        end_reshape(conf);
4640                        return 0;
4641                }
4642
4643                if (mddev->curr_resync < max_sector) /* aborted */
4644                        bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4645                                        &sync_blocks, 1);
4646                else /* completed sync */
4647                        conf->fullsync = 0;
4648                bitmap_close_sync(mddev->bitmap);
4649
4650                return 0;
4651        }
4652
4653        /* Allow raid5_quiesce to complete */
4654        wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4655
4656        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4657                return reshape_request(mddev, sector_nr, skipped);
4658
4659        /* No need to check resync_max as we never do more than one
4660         * stripe, and as resync_max will always be on a chunk boundary,
4661         * if the check in md_do_sync didn't fire, there is no chance
4662         * of overstepping resync_max here
4663         */
4664
4665        /* if there is too many failed drives and we are trying
4666         * to resync, then assert that we are finished, because there is
4667         * nothing we can do.
4668         */
4669        if (mddev->degraded >= conf->max_degraded &&
4670            test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4671                sector_t rv = mddev->dev_sectors - sector_nr;
4672                *skipped = 1;
4673                return rv;
4674        }
4675        if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4676            !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4677            !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
4678                /* we can skip this block, and probably more */
4679                sync_blocks /= STRIPE_SECTORS;
4680                *skipped = 1;
4681                return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4682        }
4683
4684        bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4685
4686        sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4687        if (sh == NULL) {
4688                sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4689                /* make sure we don't swamp the stripe cache if someone else
4690                 * is trying to get access
4691                 */
4692                schedule_timeout_uninterruptible(1);
4693        }
4694        /* Need to check if array will still be degraded after recovery/resync
4695         * We don't need to check the 'failed' flag as when that gets set,
4696         * recovery aborts.
4697         */
4698        for (i = 0; i < conf->raid_disks; i++)
4699                if (conf->disks[i].rdev == NULL)
4700                        still_degraded = 1;
4701
4702        bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4703
4704        set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4705
4706        handle_stripe(sh);
4707        release_stripe(sh);
4708
4709        return STRIPE_SECTORS;
4710}
4711
4712static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
4713{
4714        /* We may not be able to submit a whole bio at once as there
4715         * may not be enough stripe_heads available.
4716         * We cannot pre-allocate enough stripe_heads as we may need
4717         * more than exist in the cache (if we allow ever large chunks).
4718         * So we do one stripe head at a time and record in
4719         * ->bi_hw_segments how many have been done.
4720         *
4721         * We *know* that this entire raid_bio is in one chunk, so
4722         * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4723         */
4724        struct stripe_head *sh;
4725        int dd_idx;
4726        sector_t sector, logical_sector, last_sector;
4727        int scnt = 0;
4728        int remaining;
4729        int handled = 0;
4730
4731        logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4732        sector = raid5_compute_sector(conf, logical_sector,
4733                                      0, &dd_idx, NULL);
4734        last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
4735
4736        for (; logical_sector < last_sector;
4737             logical_sector += STRIPE_SECTORS,
4738                     sector += STRIPE_SECTORS,
4739                     scnt++) {
4740
4741                if (scnt < raid5_bi_processed_stripes(raid_bio))
4742                        /* already done this stripe */
4743                        continue;
4744
4745                sh = get_active_stripe(conf, sector, 0, 1, 0);
4746
4747                if (!sh) {
4748                        /* failed to get a stripe - must wait */
4749                        raid5_set_bi_processed_stripes(raid_bio, scnt);
4750                        conf->retry_read_aligned = raid_bio;
4751                        return handled;
4752                }
4753
4754                if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4755                        release_stripe(sh);
4756                        raid5_set_bi_processed_stripes(raid_bio, scnt);
4757                        conf->retry_read_aligned = raid_bio;
4758                        return handled;
4759                }
4760
4761                set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
4762                handle_stripe(sh);
4763                release_stripe(sh);
4764                handled++;
4765        }
4766        remaining =