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        struct hlist_node *hn;
 369
 370        pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 371        hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
 372                if (sh->sector == sector && sh->generation == generation)
 373                        return sh;
 374        pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 375        return NULL;
 376}
 377
 378/*
 379 * Need to check if array has failed when deciding whether to:
 380 *  - start an array
 381 *  - remove non-faulty devices
 382 *  - add a spare
 383 *  - allow a reshape
 384 * This determination is simple when no reshape is happening.
 385 * However if there is a reshape, we need to carefully check
 386 * both the before and after sections.
 387 * This is because some failed devices may only affect one
 388 * of the two sections, and some non-in_sync devices may
 389 * be insync in the section most affected by failed devices.
 390 */
 391static int calc_degraded(struct r5conf *conf)
 392{
 393        int degraded, degraded2;
 394        int i;
 395
 396        rcu_read_lock();
 397        degraded = 0;
 398        for (i = 0; i < conf->previous_raid_disks; i++) {
 399                struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 400                if (rdev && test_bit(Faulty, &rdev->flags))
 401                        rdev = rcu_dereference(conf->disks[i].replacement);
 402                if (!rdev || test_bit(Faulty, &rdev->flags))
 403                        degraded++;
 404                else if (test_bit(In_sync, &rdev->flags))
 405                        ;
 406                else
 407                        /* not in-sync or faulty.
 408                         * If the reshape increases the number of devices,
 409                         * this is being recovered by the reshape, so
 410                         * this 'previous' section is not in_sync.
 411                         * If the number of devices is being reduced however,
 412                         * the device can only be part of the array if
 413                         * we are reverting a reshape, so this section will
 414                         * be in-sync.
 415                         */
 416                        if (conf->raid_disks >= conf->previous_raid_disks)
 417                                degraded++;
 418        }
 419        rcu_read_unlock();
 420        if (conf->raid_disks == conf->previous_raid_disks)
 421                return degraded;
 422        rcu_read_lock();
 423        degraded2 = 0;
 424        for (i = 0; i < conf->raid_disks; i++) {
 425                struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 426                if (rdev && test_bit(Faulty, &rdev->flags))
 427                        rdev = rcu_dereference(conf->disks[i].replacement);
 428                if (!rdev || test_bit(Faulty, &rdev->flags))
 429                        degraded2++;
 430                else if (test_bit(In_sync, &rdev->flags))
 431                        ;
 432                else
 433                        /* not in-sync or faulty.
 434                         * If reshape increases the number of devices, this
 435                         * section has already been recovered, else it
 436                         * almost certainly hasn't.
 437                         */
 438                        if (conf->raid_disks <= conf->previous_raid_disks)
 439                                degraded2++;
 440        }
 441        rcu_read_unlock();
 442        if (degraded2 > degraded)
 443                return degraded2;
 444        return degraded;
 445}
 446
 447static int has_failed(struct r5conf *conf)
 448{
 449        int degraded;
 450
 451        if (conf->mddev->reshape_position == MaxSector)
 452                return conf->mddev->degraded > conf->max_degraded;
 453
 454        degraded = calc_degraded(conf);
 455        if (degraded > conf->max_degraded)
 456                return 1;
 457        return 0;
 458}
 459
 460static struct stripe_head *
 461get_active_stripe(struct r5conf *conf, sector_t sector,
 462                  int previous, int noblock, int noquiesce)
 463{
 464        struct stripe_head *sh;
 465
 466        pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 467
 468        spin_lock_irq(&conf->device_lock);
 469
 470        do {
 471                wait_event_lock_irq(conf->wait_for_stripe,
 472                                    conf->quiesce == 0 || noquiesce,
 473                                    conf->device_lock);
 474                sh = __find_stripe(conf, sector, conf->generation - previous);
 475                if (!sh) {
 476                        if (!conf->inactive_blocked)
 477                                sh = get_free_stripe(conf);
 478                        if (noblock && sh == NULL)
 479                                break;
 480                        if (!sh) {
 481                                conf->inactive_blocked = 1;
 482                                wait_event_lock_irq(conf->wait_for_stripe,
 483                                                    !list_empty(&conf->inactive_list) &&
 484                                                    (atomic_read(&conf->active_stripes)
 485                                                     < (conf->max_nr_stripes *3/4)
 486                                                     || !conf->inactive_blocked),
 487                                                    conf->device_lock);
 488                                conf->inactive_blocked = 0;
 489                        } else
 490                                init_stripe(sh, sector, previous);
 491                } else {
 492                        if (atomic_read(&sh->count)) {
 493                                BUG_ON(!list_empty(&sh->lru)
 494                                    && !test_bit(STRIPE_EXPANDING, &sh->state)
 495                                    && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
 496                        } else {
 497                                if (!test_bit(STRIPE_HANDLE, &sh->state))
 498                                        atomic_inc(&conf->active_stripes);
 499                                if (list_empty(&sh->lru) &&
 500                                    !test_bit(STRIPE_EXPANDING, &sh->state))
 501                                        BUG();
 502                                list_del_init(&sh->lru);
 503                        }
 504                }
 505        } while (sh == NULL);
 506
 507        if (sh)
 508                atomic_inc(&sh->count);
 509
 510        spin_unlock_irq(&conf->device_lock);
 511        return sh;
 512}
 513
 514/* Determine if 'data_offset' or 'new_data_offset' should be used
 515 * in this stripe_head.
 516 */
 517static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 518{
 519        sector_t progress = conf->reshape_progress;
 520        /* Need a memory barrier to make sure we see the value
 521         * of conf->generation, or ->data_offset that was set before
 522         * reshape_progress was updated.
 523         */
 524        smp_rmb();
 525        if (progress == MaxSector)
 526                return 0;
 527        if (sh->generation == conf->generation - 1)
 528                return 0;
 529        /* We are in a reshape, and this is a new-generation stripe,
 530         * so use new_data_offset.
 531         */
 532        return 1;
 533}
 534
 535static void
 536raid5_end_read_request(struct bio *bi, int error);
 537static void
 538raid5_end_write_request(struct bio *bi, int error);
 539
 540static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 541{
 542        struct r5conf *conf = sh->raid_conf;
 543        int i, disks = sh->disks;
 544
 545        might_sleep();
 546
 547        for (i = disks; i--; ) {
 548                int rw;
 549                int replace_only = 0;
 550                struct bio *bi, *rbi;
 551                struct md_rdev *rdev, *rrdev = NULL;
 552                if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 553                        if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 554                                rw = WRITE_FUA;
 555                        else
 556                                rw = WRITE;
 557                        if (test_bit(R5_Discard, &sh->dev[i].flags))
 558                                rw |= REQ_DISCARD;
 559                } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 560                        rw = READ;
 561                else if (test_and_clear_bit(R5_WantReplace,
 562                                            &sh->dev[i].flags)) {
 563                        rw = WRITE;
 564                        replace_only = 1;
 565                } else
 566                        continue;
 567                if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 568                        rw |= REQ_SYNC;
 569
 570                bi = &sh->dev[i].req;
 571                rbi = &sh->dev[i].rreq; /* For writing to replacement */
 572
 573                bi->bi_rw = rw;
 574                rbi->bi_rw = rw;
 575                if (rw & WRITE) {
 576                        bi->bi_end_io = raid5_end_write_request;
 577                        rbi->bi_end_io = raid5_end_write_request;
 578                } else
 579                        bi->bi_end_io = raid5_end_read_request;
 580
 581                rcu_read_lock();
 582                rrdev = rcu_dereference(conf->disks[i].replacement);
 583                smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 584                rdev = rcu_dereference(conf->disks[i].rdev);
 585                if (!rdev) {
 586                        rdev = rrdev;
 587                        rrdev = NULL;
 588                }
 589                if (rw & WRITE) {
 590                        if (replace_only)
 591                                rdev = NULL;
 592                        if (rdev == rrdev)
 593                                /* We raced and saw duplicates */
 594                                rrdev = NULL;
 595                } else {
 596                        if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
 597                                rdev = rrdev;
 598                        rrdev = NULL;
 599                }
 600
 601                if (rdev && test_bit(Faulty, &rdev->flags))
 602                        rdev = NULL;
 603                if (rdev)
 604                        atomic_inc(&rdev->nr_pending);
 605                if (rrdev && test_bit(Faulty, &rrdev->flags))
 606                        rrdev = NULL;
 607                if (rrdev)
 608                        atomic_inc(&rrdev->nr_pending);
 609                rcu_read_unlock();
 610
 611                /* We have already checked bad blocks for reads.  Now
 612                 * need to check for writes.  We never accept write errors
 613                 * on the replacement, so we don't to check rrdev.
 614                 */
 615                while ((rw & WRITE) && rdev &&
 616                       test_bit(WriteErrorSeen, &rdev->flags)) {
 617                        sector_t first_bad;
 618                        int bad_sectors;
 619                        int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 620                                              &first_bad, &bad_sectors);
 621                        if (!bad)
 622                                break;
 623
 624                        if (bad < 0) {
 625                                set_bit(BlockedBadBlocks, &rdev->flags);
 626                                if (!conf->mddev->external &&
 627                                    conf->mddev->flags) {
 628                                        /* It is very unlikely, but we might
 629                                         * still need to write out the
 630                                         * bad block log - better give it
 631                                         * a chance*/
 632                                        md_check_recovery(conf->mddev);
 633                                }
 634                                /*
 635                                 * Because md_wait_for_blocked_rdev
 636                                 * will dec nr_pending, we must
 637                                 * increment it first.
 638                                 */
 639                                atomic_inc(&rdev->nr_pending);
 640                                md_wait_for_blocked_rdev(rdev, conf->mddev);
 641                        } else {
 642                                /* Acknowledged bad block - skip the write */
 643                                rdev_dec_pending(rdev, conf->mddev);
 644                                rdev = NULL;
 645                        }
 646                }
 647
 648                if (rdev) {
 649                        if (s->syncing || s->expanding || s->expanded
 650                            || s->replacing)
 651                                md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 652
 653                        set_bit(STRIPE_IO_STARTED, &sh->state);
 654
 655                        bi->bi_bdev = rdev->bdev;
 656                        pr_debug("%s: for %llu schedule op %ld on disc %d\n",
 657                                __func__, (unsigned long long)sh->sector,
 658                                bi->bi_rw, i);
 659                        atomic_inc(&sh->count);
 660                        if (use_new_offset(conf, sh))
 661                                bi->bi_sector = (sh->sector
 662                                                 + rdev->new_data_offset);
 663                        else
 664                                bi->bi_sector = (sh->sector
 665                                                 + rdev->data_offset);
 666                        if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
 667                                bi->bi_rw |= REQ_FLUSH;
 668
 669                        bi->bi_flags = 1 << BIO_UPTODATE;
 670                        bi->bi_idx = 0;
 671                        bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 672                        bi->bi_io_vec[0].bv_offset = 0;
 673                        bi->bi_size = STRIPE_SIZE;
 674                        bi->bi_next = NULL;
 675                        if (rrdev)
 676                                set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
 677                        trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
 678                                              bi, disk_devt(conf->mddev->gendisk),
 679                                              sh->dev[i].sector);
 680                        generic_make_request(bi);
 681                }
 682                if (rrdev) {
 683                        if (s->syncing || s->expanding || s->expanded
 684                            || s->replacing)
 685                                md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
 686
 687                        set_bit(STRIPE_IO_STARTED, &sh->state);
 688
 689                        rbi->bi_bdev = rrdev->bdev;
 690                        pr_debug("%s: for %llu schedule op %ld on "
 691                                 "replacement disc %d\n",
 692                                __func__, (unsigned long long)sh->sector,
 693                                rbi->bi_rw, i);
 694                        atomic_inc(&sh->count);
 695                        if (use_new_offset(conf, sh))
 696                                rbi->bi_sector = (sh->sector
 697                                                  + rrdev->new_data_offset);
 698                        else
 699                                rbi->bi_sector = (sh->sector
 700                                                  + rrdev->data_offset);
 701                        rbi->bi_flags = 1 << BIO_UPTODATE;
 702                        rbi->bi_idx = 0;
 703                        rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 704                        rbi->bi_io_vec[0].bv_offset = 0;
 705                        rbi->bi_size = STRIPE_SIZE;
 706                        rbi->bi_next = NULL;
 707                        trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
 708                                              rbi, disk_devt(conf->mddev->gendisk),
 709                                              sh->dev[i].sector);
 710                        generic_make_request(rbi);
 711                }
 712                if (!rdev && !rrdev) {
 713                        if (rw & WRITE)
 714                                set_bit(STRIPE_DEGRADED, &sh->state);
 715                        pr_debug("skip op %ld on disc %d for sector %llu\n",
 716                                bi->bi_rw, i, (unsigned long long)sh->sector);
 717                        clear_bit(R5_LOCKED, &sh->dev[i].flags);
 718                        set_bit(STRIPE_HANDLE, &sh->state);
 719                }
 720        }
 721}
 722
 723static struct dma_async_tx_descriptor *
 724async_copy_data(int frombio, struct bio *bio, struct page *page,
 725        sector_t sector, struct dma_async_tx_descriptor *tx)
 726{
 727        struct bio_vec *bvl;
 728        struct page *bio_page;
 729        int i;
 730        int page_offset;
 731        struct async_submit_ctl submit;
 732        enum async_tx_flags flags = 0;
 733
 734        if (bio->bi_sector >= sector)
 735                page_offset = (signed)(bio->bi_sector - sector) * 512;
 736        else
 737                page_offset = (signed)(sector - bio->bi_sector) * -512;
 738
 739        if (frombio)
 740                flags |= ASYNC_TX_FENCE;
 741        init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
 742
 743        bio_for_each_segment(bvl, bio, i) {
 744                int len = bvl->bv_len;
 745                int clen;
 746                int b_offset = 0;
 747
 748                if (page_offset < 0) {
 749                        b_offset = -page_offset;
 750                        page_offset += b_offset;
 751                        len -= b_offset;
 752                }
 753
 754                if (len > 0 && page_offset + len > STRIPE_SIZE)
 755                        clen = STRIPE_SIZE - page_offset;
 756                else
 757                        clen = len;
 758
 759                if (clen > 0) {
 760                        b_offset += bvl->bv_offset;
 761                        bio_page = bvl->bv_page;
 762                        if (frombio)
 763                                tx = async_memcpy(page, bio_page, page_offset,
 764                                                  b_offset, clen, &submit);
 765                        else
 766                                tx = async_memcpy(bio_page, page, b_offset,
 767                                                  page_offset, clen, &submit);
 768                }
 769                /* chain the operations */
 770                submit.depend_tx = tx;
 771
 772                if (clen < len) /* hit end of page */
 773                        break;
 774                page_offset +=  len;
 775        }
 776
 777        return tx;
 778}
 779
 780static void ops_complete_biofill(void *stripe_head_ref)
 781{
 782        struct stripe_head *sh = stripe_head_ref;
 783        struct bio *return_bi = NULL;
 784        int i;
 785
 786        pr_debug("%s: stripe %llu\n", __func__,
 787                (unsigned long long)sh->sector);
 788
 789        /* clear completed biofills */
 790        for (i = sh->disks; i--; ) {
 791                struct r5dev *dev = &sh->dev[i];
 792
 793                /* acknowledge completion of a biofill operation */
 794                /* and check if we need to reply to a read request,
 795                 * new R5_Wantfill requests are held off until
 796                 * !STRIPE_BIOFILL_RUN
 797                 */
 798                if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
 799                        struct bio *rbi, *rbi2;
 800
 801                        BUG_ON(!dev->read);
 802                        rbi = dev->read;
 803                        dev->read = NULL;
 804                        while (rbi && rbi->bi_sector <
 805                                dev->sector + STRIPE_SECTORS) {
 806                                rbi2 = r5_next_bio(rbi, dev->sector);
 807                                if (!raid5_dec_bi_active_stripes(rbi)) {
 808                                        rbi->bi_next = return_bi;
 809                                        return_bi = rbi;
 810                                }
 811                                rbi = rbi2;
 812                        }
 813                }
 814        }
 815        clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
 816
 817        return_io(return_bi);
 818
 819        set_bit(STRIPE_HANDLE, &sh->state);
 820        release_stripe(sh);
 821}
 822
 823static void ops_run_biofill(struct stripe_head *sh)
 824{
 825        struct dma_async_tx_descriptor *tx = NULL;
 826        struct async_submit_ctl submit;
 827        int i;
 828
 829        pr_debug("%s: stripe %llu\n", __func__,
 830                (unsigned long long)sh->sector);
 831
 832        for (i = sh->disks; i--; ) {
 833                struct r5dev *dev = &sh->dev[i];
 834                if (test_bit(R5_Wantfill, &dev->flags)) {
 835                        struct bio *rbi;
 836                        spin_lock_irq(&sh->stripe_lock);
 837                        dev->read = rbi = dev->toread;
 838                        dev->toread = NULL;
 839                        spin_unlock_irq(&sh->stripe_lock);
 840                        while (rbi && rbi->bi_sector <
 841                                dev->sector + STRIPE_SECTORS) {
 842                                tx = async_copy_data(0, rbi, dev->page,
 843                                        dev->sector, tx);
 844                                rbi = r5_next_bio(rbi, dev->sector);
 845                        }
 846                }
 847        }
 848
 849        atomic_inc(&sh->count);
 850        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
 851        async_trigger_callback(&submit);
 852}
 853
 854static void mark_target_uptodate(struct stripe_head *sh, int target)
 855{
 856        struct r5dev *tgt;
 857
 858        if (target < 0)
 859                return;
 860
 861        tgt = &sh->dev[target];
 862        set_bit(R5_UPTODATE, &tgt->flags);
 863        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 864        clear_bit(R5_Wantcompute, &tgt->flags);
 865}
 866
 867static void ops_complete_compute(void *stripe_head_ref)
 868{
 869        struct stripe_head *sh = stripe_head_ref;
 870
 871        pr_debug("%s: stripe %llu\n", __func__,
 872                (unsigned long long)sh->sector);
 873
 874        /* mark the computed target(s) as uptodate */
 875        mark_target_uptodate(sh, sh->ops.target);
 876        mark_target_uptodate(sh, sh->ops.target2);
 877
 878        clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
 879        if (sh->check_state == check_state_compute_run)
 880                sh->check_state = check_state_compute_result;
 881        set_bit(STRIPE_HANDLE, &sh->state);
 882        release_stripe(sh);
 883}
 884
 885/* return a pointer to the address conversion region of the scribble buffer */
 886static addr_conv_t *to_addr_conv(struct stripe_head *sh,
 887                                 struct raid5_percpu *percpu)
 888{
 889        return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
 890}
 891
 892static struct dma_async_tx_descriptor *
 893ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
 894{
 895        int disks = sh->disks;
 896        struct page **xor_srcs = percpu->scribble;
 897        int target = sh->ops.target;
 898        struct r5dev *tgt = &sh->dev[target];
 899        struct page *xor_dest = tgt->page;
 900        int count = 0;
 901        struct dma_async_tx_descriptor *tx;
 902        struct async_submit_ctl submit;
 903        int i;
 904
 905        pr_debug("%s: stripe %llu block: %d\n",
 906                __func__, (unsigned long long)sh->sector, target);
 907        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 908
 909        for (i = disks; i--; )
 910                if (i != target)
 911                        xor_srcs[count++] = sh->dev[i].page;
 912
 913        atomic_inc(&sh->count);
 914
 915        init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
 916                          ops_complete_compute, sh, to_addr_conv(sh, percpu));
 917        if (unlikely(count == 1))
 918                tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
 919        else
 920                tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
 921
 922        return tx;
 923}
 924
 925/* set_syndrome_sources - populate source buffers for gen_syndrome
 926 * @srcs - (struct page *) array of size sh->disks
 927 * @sh - stripe_head to parse
 928 *
 929 * Populates srcs in proper layout order for the stripe and returns the
 930 * 'count' of sources to be used in a call to async_gen_syndrome.  The P
 931 * destination buffer is recorded in srcs[count] and the Q destination
 932 * is recorded in srcs[count+1]].
 933 */
 934static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
 935{
 936        int disks = sh->disks;
 937        int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
 938        int d0_idx = raid6_d0(sh);
 939        int count;
 940        int i;
 941
 942        for (i = 0; i < disks; i++)
 943                srcs[i] = NULL;
 944
 945        count = 0;
 946        i = d0_idx;
 947        do {
 948                int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
 949
 950                srcs[slot] = sh->dev[i].page;
 951                i = raid6_next_disk(i, disks);
 952        } while (i != d0_idx);
 953
 954        return syndrome_disks;
 955}
 956
 957static struct dma_async_tx_descriptor *
 958ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
 959{
 960        int disks = sh->disks;
 961        struct page **blocks = percpu->scribble;
 962        int target;
 963        int qd_idx = sh->qd_idx;
 964        struct dma_async_tx_descriptor *tx;
 965        struct async_submit_ctl submit;
 966        struct r5dev *tgt;
 967        struct page *dest;
 968        int i;
 969        int count;
 970
 971        if (sh->ops.target < 0)
 972                target = sh->ops.target2;
 973        else if (sh->ops.target2 < 0)
 974                target = sh->ops.target;
 975        else
 976                /* we should only have one valid target */
 977                BUG();
 978        BUG_ON(target < 0);
 979        pr_debug("%s: stripe %llu block: %d\n",
 980                __func__, (unsigned long long)sh->sector, target);
 981
 982        tgt = &sh->dev[target];
 983        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 984        dest = tgt->page;
 985
 986        atomic_inc(&sh->count);
 987
 988        if (target == qd_idx) {
 989                count = set_syndrome_sources(blocks, sh);
 990                blocks[count] = NULL; /* regenerating p is not necessary */
 991                BUG_ON(blocks[count+1] != dest); /* q should already be set */
 992                init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
 993                                  ops_complete_compute, sh,
 994                                  to_addr_conv(sh, percpu));
 995                tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
 996        } else {
 997                /* Compute any data- or p-drive using XOR */
 998                count = 0;
 999                for (i = disks; i-- ; ) {
1000                        if (i == target || i == qd_idx)
1001                                continue;
1002                        blocks[count++] = sh->dev[i].page;
1003                }
1004
1005                init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1006                                  NULL, ops_complete_compute, sh,
1007                                  to_addr_conv(sh, percpu));
1008                tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1009        }
1010
1011        return tx;
1012}
1013
1014static struct dma_async_tx_descriptor *
1015ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1016{
1017        int i, count, disks = sh->disks;
1018        int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1019        int d0_idx = raid6_d0(sh);
1020        int faila = -1, failb = -1;
1021        int target = sh->ops.target;
1022        int target2 = sh->ops.target2;
1023        struct r5dev *tgt = &sh->dev[target];
1024        struct r5dev *tgt2 = &sh->dev[target2];
1025        struct dma_async_tx_descriptor *tx;
1026        struct page **blocks = percpu->scribble;
1027        struct async_submit_ctl submit;
1028
1029        pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1030                 __func__, (unsigned long long)sh->sector, target, target2);
1031        BUG_ON(target < 0 || target2 < 0);
1032        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1033        BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1034
1035        /* we need to open-code set_syndrome_sources to handle the
1036         * slot number conversion for 'faila' and 'failb'
1037         */
1038        for (i = 0; i < disks ; i++)
1039                blocks[i] = NULL;
1040        count = 0;
1041        i = d0_idx;
1042        do {
1043                int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1044
1045                blocks[slot] = sh->dev[i].page;
1046
1047                if (i == target)
1048                        faila = slot;
1049                if (i == target2)
1050                        failb = slot;
1051                i = raid6_next_disk(i, disks);
1052        } while (i != d0_idx);
1053
1054        BUG_ON(faila == failb);
1055        if (failb < faila)
1056                swap(faila, failb);
1057        pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1058                 __func__, (unsigned long long)sh->sector, faila, failb);
1059
1060        atomic_inc(&sh->count);
1061
1062        if (failb == syndrome_disks+1) {
1063                /* Q disk is one of the missing disks */
1064                if (faila == syndrome_disks) {
1065                        /* Missing P+Q, just recompute */
1066                        init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1067                                          ops_complete_compute, sh,
1068                                          to_addr_conv(sh, percpu));
1069                        return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1070                                                  STRIPE_SIZE, &submit);
1071                } else {
1072                        struct page *dest;
1073                        int data_target;
1074                        int qd_idx = sh->qd_idx;
1075
1076                        /* Missing D+Q: recompute D from P, then recompute Q */
1077                        if (target == qd_idx)
1078                                data_target = target2;
1079                        else
1080                                data_target = target;
1081
1082                        count = 0;
1083                        for (i = disks; i-- ; ) {
1084                                if (i == data_target || i == qd_idx)
1085                                        continue;
1086                                blocks[count++] = sh->dev[i].page;
1087                        }
1088                        dest = sh->dev[data_target].page;
1089                        init_async_submit(&submit,
1090                                          ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1091                                          NULL, NULL, NULL,
1092                                          to_addr_conv(sh, percpu));
1093                        tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1094                                       &submit);
1095
1096                        count = set_syndrome_sources(blocks, sh);
1097                        init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1098                                          ops_complete_compute, sh,
1099                                          to_addr_conv(sh, percpu));
1100                        return async_gen_syndrome(blocks, 0, count+2,
1101                                                  STRIPE_SIZE, &submit);
1102                }
1103        } else {
1104                init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1105                                  ops_complete_compute, sh,
1106                                  to_addr_conv(sh, percpu));
1107                if (failb == syndrome_disks) {
1108                        /* We're missing D+P. */
1109                        return async_raid6_datap_recov(syndrome_disks+2,
1110                                                       STRIPE_SIZE, faila,
1111                                                       blocks, &submit);
1112                } else {
1113                        /* We're missing D+D. */
1114                        return async_raid6_2data_recov(syndrome_disks+2,
1115                                                       STRIPE_SIZE, faila, failb,
1116                                                       blocks, &submit);
1117                }
1118        }
1119}
1120
1121
1122static void ops_complete_prexor(void *stripe_head_ref)
1123{
1124        struct stripe_head *sh = stripe_head_ref;
1125
1126        pr_debug("%s: stripe %llu\n", __func__,
1127                (unsigned long long)sh->sector);
1128}
1129
1130static struct dma_async_tx_descriptor *
1131ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1132               struct dma_async_tx_descriptor *tx)
1133{
1134        int disks = sh->disks;
1135        struct page **xor_srcs = percpu->scribble;
1136        int count = 0, pd_idx = sh->pd_idx, i;
1137        struct async_submit_ctl submit;
1138
1139        /* existing parity data subtracted */
1140        struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1141
1142        pr_debug("%s: stripe %llu\n", __func__,
1143                (unsigned long long)sh->sector);
1144
1145        for (i = disks; i--; ) {
1146                struct r5dev *dev = &sh->dev[i];
1147                /* Only process blocks that are known to be uptodate */
1148                if (test_bit(R5_Wantdrain, &dev->flags))
1149                        xor_srcs[count++] = dev->page;
1150        }
1151
1152        init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1153                          ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1154        tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1155
1156        return tx;
1157}
1158
1159static struct dma_async_tx_descriptor *
1160ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1161{
1162        int disks = sh->disks;
1163        int i;
1164
1165        pr_debug("%s: stripe %llu\n", __func__,
1166                (unsigned long long)sh->sector);
1167
1168        for (i = disks; i--; ) {
1169                struct r5dev *dev = &sh->dev[i];
1170                struct bio *chosen;
1171
1172                if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1173                        struct bio *wbi;
1174
1175                        spin_lock_irq(&sh->stripe_lock);
1176                        chosen = dev->towrite;
1177                        dev->towrite = NULL;
1178                        BUG_ON(dev->written);
1179                        wbi = dev->written = chosen;
1180                        spin_unlock_irq(&sh->stripe_lock);
1181
1182                        while (wbi && wbi->bi_sector <
1183                                dev->sector + STRIPE_SECTORS) {
1184                                if (wbi->bi_rw & REQ_FUA)
1185                                        set_bit(R5_WantFUA, &dev->flags);
1186                                if (wbi->bi_rw & REQ_SYNC)
1187                                        set_bit(R5_SyncIO, &dev->flags);
1188                                if (wbi->bi_rw & REQ_DISCARD)
1189                                        set_bit(R5_Discard, &dev->flags);
1190                                else
1191                                        tx = async_copy_data(1, wbi, dev->page,
1192                                                dev->sector, tx);
1193                                wbi = r5_next_bio(wbi, dev->sector);
1194                        }
1195                }
1196        }
1197
1198        return tx;
1199}
1200
1201static void ops_complete_reconstruct(void *stripe_head_ref)
1202{
1203        struct stripe_head *sh = stripe_head_ref;
1204        int disks = sh->disks;
1205        int pd_idx = sh->pd_idx;
1206        int qd_idx = sh->qd_idx;
1207        int i;
1208        bool fua = false, sync = false, discard = false;
1209
1210        pr_debug("%s: stripe %llu\n", __func__,
1211                (unsigned long long)sh->sector);
1212
1213        for (i = disks; i--; ) {
1214                fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1215                sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1216                discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1217        }
1218
1219        for (i = disks; i--; ) {
1220                struct r5dev *dev = &sh->dev[i];
1221
1222                if (dev->written || i == pd_idx || i == qd_idx) {
1223                        if (!discard)
1224                                set_bit(R5_UPTODATE, &dev->flags);
1225                        if (fua)
1226                                set_bit(R5_WantFUA, &dev->flags);
1227                        if (sync)
1228                                set_bit(R5_SyncIO, &dev->flags);
1229                }
1230        }
1231
1232        if (sh->reconstruct_state == reconstruct_state_drain_run)
1233                sh->reconstruct_state = reconstruct_state_drain_result;
1234        else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1235                sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1236        else {
1237                BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1238                sh->reconstruct_state = reconstruct_state_result;
1239        }
1240
1241        set_bit(STRIPE_HANDLE, &sh->state);
1242        release_stripe(sh);
1243}
1244
1245static void
1246ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1247                     struct dma_async_tx_descriptor *tx)
1248{
1249        int disks = sh->disks;
1250        struct page **xor_srcs = percpu->scribble;
1251        struct async_submit_ctl submit;
1252        int count = 0, pd_idx = sh->pd_idx, i;
1253        struct page *xor_dest;
1254        int prexor = 0;
1255        unsigned long flags;
1256
1257        pr_debug("%s: stripe %llu\n", __func__,
1258                (unsigned long long)sh->sector);
1259
1260        for (i = 0; i < sh->disks; i++) {
1261                if (pd_idx == i)
1262                        continue;
1263                if (!test_bit(R5_Discard, &sh->dev[i].flags))
1264                        break;
1265        }
1266        if (i >= sh->disks) {
1267                atomic_inc(&sh->count);
1268                set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1269                ops_complete_reconstruct(sh);
1270                return;
1271        }
1272        /* check if prexor is active which means only process blocks
1273         * that are part of a read-modify-write (written)
1274         */
1275        if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1276                prexor = 1;
1277                xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1278                for (i = disks; i--; ) {
1279                        struct r5dev *dev = &sh->dev[i];
1280                        if (dev->written)
1281                                xor_srcs[count++] = dev->page;
1282                }
1283        } else {
1284                xor_dest = sh->dev[pd_idx].page;
1285                for (i = disks; i--; ) {
1286                        struct r5dev *dev = &sh->dev[i];
1287                        if (i != pd_idx)
1288                                xor_srcs[count++] = dev->page;
1289                }
1290        }
1291
1292        /* 1/ if we prexor'd then the dest is reused as a source
1293         * 2/ if we did not prexor then we are redoing the parity
1294         * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1295         * for the synchronous xor case
1296         */
1297        flags = ASYNC_TX_ACK |
1298                (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1299
1300        atomic_inc(&sh->count);
1301
1302        init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1303                          to_addr_conv(sh, percpu));
1304        if (unlikely(count == 1))
1305                tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1306        else
1307                tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1308}
1309
1310static void
1311ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1312                     struct dma_async_tx_descriptor *tx)
1313{
1314        struct async_submit_ctl submit;
1315        struct page **blocks = percpu->scribble;
1316        int count, i;
1317
1318        pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1319
1320        for (i = 0; i < sh->disks; i++) {
1321                if (sh->pd_idx == i || sh->qd_idx == i)
1322                        continue;
1323                if (!test_bit(R5_Discard, &sh->dev[i].flags))
1324                        break;
1325        }
1326        if (i >= sh->disks) {
1327                atomic_inc(&sh->count);
1328                set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1329                set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1330                ops_complete_reconstruct(sh);
1331                return;
1332        }
1333
1334        count = set_syndrome_sources(blocks, sh);
1335
1336        atomic_inc(&sh->count);
1337
1338        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1339                          sh, to_addr_conv(sh, percpu));
1340        async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1341}
1342
1343static void ops_complete_check(void *stripe_head_ref)
1344{
1345        struct stripe_head *sh = stripe_head_ref;
1346
1347        pr_debug("%s: stripe %llu\n", __func__,
1348                (unsigned long long)sh->sector);
1349
1350        sh->check_state = check_state_check_result;
1351        set_bit(STRIPE_HANDLE, &sh->state);
1352        release_stripe(sh);
1353}
1354
1355static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1356{
1357        int disks = sh->disks;
1358        int pd_idx = sh->pd_idx;
1359        int qd_idx = sh->qd_idx;
1360        struct page *xor_dest;
1361        struct page **xor_srcs = percpu->scribble;
1362        struct dma_async_tx_descriptor *tx;
1363        struct async_submit_ctl submit;
1364        int count;
1365        int i;
1366
1367        pr_debug("%s: stripe %llu\n", __func__,
1368                (unsigned long long)sh->sector);
1369
1370        count = 0;
1371        xor_dest = sh->dev[pd_idx].page;
1372        xor_srcs[count++] = xor_dest;
1373        for (i = disks; i--; ) {
1374                if (i == pd_idx || i == qd_idx)
1375                        continue;
1376                xor_srcs[count++] = sh->dev[i].page;
1377        }
1378
1379        init_async_submit(&submit, 0, NULL, NULL, NULL,
1380                          to_addr_conv(sh, percpu));
1381        tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1382                           &sh->ops.zero_sum_result, &submit);
1383
1384        atomic_inc(&sh->count);
1385        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1386        tx = async_trigger_callback(&submit);
1387}
1388
1389static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1390{
1391        struct page **srcs = percpu->scribble;
1392        struct async_submit_ctl submit;
1393        int count;
1394
1395        pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1396                (unsigned long long)sh->sector, checkp);
1397
1398        count = set_syndrome_sources(srcs, sh);
1399        if (!checkp)
1400                srcs[count] = NULL;
1401
1402        atomic_inc(&sh->count);
1403        init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1404                          sh, to_addr_conv(sh, percpu));
1405        async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1406                           &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1407}
1408
1409static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1410{
1411        int overlap_clear = 0, i, disks = sh->disks;
1412        struct dma_async_tx_descriptor *tx = NULL;
1413        struct r5conf *conf = sh->raid_conf;
1414        int level = conf->level;
1415        struct raid5_percpu *percpu;
1416        unsigned long cpu;
1417
1418        cpu = get_cpu();
1419        percpu = per_cpu_ptr(conf->percpu, cpu);
1420        if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1421                ops_run_biofill(sh);
1422                overlap_clear++;
1423        }
1424
1425        if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1426                if (level < 6)
1427                        tx = ops_run_compute5(sh, percpu);
1428                else {
1429                        if (sh->ops.target2 < 0 || sh->ops.target < 0)
1430                                tx = ops_run_compute6_1(sh, percpu);
1431                        else
1432                                tx = ops_run_compute6_2(sh, percpu);
1433                }
1434                /* terminate the chain if reconstruct is not set to be run */
1435                if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1436                        async_tx_ack(tx);
1437        }
1438
1439        if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1440                tx = ops_run_prexor(sh, percpu, tx);
1441
1442        if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1443                tx = ops_run_biodrain(sh, tx);
1444                overlap_clear++;
1445        }
1446
1447        if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1448                if (level < 6)
1449                        ops_run_reconstruct5(sh, percpu, tx);
1450                else
1451                        ops_run_reconstruct6(sh, percpu, tx);
1452        }
1453
1454        if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1455                if (sh->check_state == check_state_run)
1456                        ops_run_check_p(sh, percpu);
1457                else if (sh->check_state == check_state_run_q)
1458                        ops_run_check_pq(sh, percpu, 0);
1459                else if (sh->check_state == check_state_run_pq)
1460                        ops_run_check_pq(sh, percpu, 1);
1461                else
1462                        BUG();
1463        }
1464
1465        if (overlap_clear)
1466                for (i = disks; i--; ) {
1467                        struct r5dev *dev = &sh->dev[i];
1468                        if (test_and_clear_bit(R5_Overlap, &dev->flags))
1469                                wake_up(&sh->raid_conf->wait_for_overlap);
1470                }
1471        put_cpu();
1472}
1473
1474#ifdef CONFIG_MULTICORE_RAID456
1475static void async_run_ops(void *param, async_cookie_t cookie)
1476{
1477        struct stripe_head *sh = param;
1478        unsigned long ops_request = sh->ops.request;
1479
1480        clear_bit_unlock(STRIPE_OPS_REQ_PENDING, &sh->state);
1481        wake_up(&sh->ops.wait_for_ops);
1482
1483        __raid_run_ops(sh, ops_request);
1484        release_stripe(sh);
1485}
1486
1487static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1488{
1489        /* since handle_stripe can be called outside of raid5d context
1490         * we need to ensure sh->ops.request is de-staged before another
1491         * request arrives
1492         */
1493        wait_event(sh->ops.wait_for_ops,
1494                   !test_and_set_bit_lock(STRIPE_OPS_REQ_PENDING, &sh->state));
1495        sh->ops.request = ops_request;
1496
1497        atomic_inc(&sh->count);
1498        async_schedule(async_run_ops, sh);
1499}
1500#else
1501#define raid_run_ops __raid_run_ops
1502#endif
1503
1504static int grow_one_stripe(struct r5conf *conf)
1505{
1506        struct stripe_head *sh;
1507        sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1508        if (!sh)
1509                return 0;
1510
1511        sh->raid_conf = conf;
1512        #ifdef CONFIG_MULTICORE_RAID456
1513        init_waitqueue_head(&sh->ops.wait_for_ops);
1514        #endif
1515
1516        spin_lock_init(&sh->stripe_lock);
1517
1518        if (grow_buffers(sh)) {
1519                shrink_buffers(sh);
1520                kmem_cache_free(conf->slab_cache, sh);
1521                return 0;
1522        }
1523        /* we just created an active stripe so... */
1524        atomic_set(&sh->count, 1);
1525        atomic_inc(&conf->active_stripes);
1526        INIT_LIST_HEAD(&sh->lru);
1527        release_stripe(sh);
1528        return 1;
1529}
1530
1531static int grow_stripes(struct r5conf *conf, int num)
1532{
1533        struct kmem_cache *sc;
1534        int devs = max(conf->raid_disks, conf->previous_raid_disks);
1535
1536        if (conf->mddev->gendisk)
1537                sprintf(conf->cache_name[0],
1538                        "raid%d-%s", conf->level, mdname(conf->mddev));
1539        else
1540                sprintf(conf->cache_name[0],
1541                        "raid%d-%p", conf->level, conf->mddev);
1542        sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1543
1544        conf->active_name = 0;
1545        sc = kmem_cache_create(conf->cache_name[conf->active_name],
1546                               sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1547                               0, 0, NULL);
1548        if (!sc)
1549                return 1;
1550        conf->slab_cache = sc;
1551        conf->pool_size = devs;
1552        while (num--)
1553                if (!grow_one_stripe(conf))
1554                        return 1;
1555        return 0;
1556}
1557
1558/**
1559 * scribble_len - return the required size of the scribble region
1560 * @num - total number of disks in the array
1561 *
1562 * The size must be enough to contain:
1563 * 1/ a struct page pointer for each device in the array +2
1564 * 2/ room to convert each entry in (1) to its corresponding dma
1565 *    (dma_map_page()) or page (page_address()) address.
1566 *
1567 * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1568 * calculate over all devices (not just the data blocks), using zeros in place
1569 * of the P and Q blocks.
1570 */
1571static size_t scribble_len(int num)
1572{
1573        size_t len;
1574
1575        len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1576
1577        return len;
1578}
1579
1580static int resize_stripes(struct r5conf *conf, int newsize)
1581{
1582        /* Make all the stripes able to hold 'newsize' devices.
1583         * New slots in each stripe get 'page' set to a new page.
1584         *
1585         * This happens in stages:
1586         * 1/ create a new kmem_cache and allocate the required number of
1587         *    stripe_heads.
1588         * 2/ gather all the old stripe_heads and transfer the pages across
1589         *    to the new stripe_heads.  This will have the side effect of
1590         *    freezing the array as once all stripe_heads have been collected,
1591         *    no IO will be possible.  Old stripe heads are freed once their
1592         *    pages have been transferred over, and the old kmem_cache is
1593         *    freed when all stripes are done.
1594         * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1595         *    we simple return a failre status - no need to clean anything up.
1596         * 4/ allocate new pages for the new slots in the new stripe_heads.
1597         *    If this fails, we don't bother trying the shrink the
1598         *    stripe_heads down again, we just leave them as they are.
1599         *    As each stripe_head is processed the new one is released into
1600         *    active service.
1601         *
1602         * Once step2 is started, we cannot afford to wait for a write,
1603         * so we use GFP_NOIO allocations.
1604         */
1605        struct stripe_head *osh, *nsh;
1606        LIST_HEAD(newstripes);
1607        struct disk_info *ndisks;
1608        unsigned long cpu;
1609        int err;
1610        struct kmem_cache *sc;
1611        int i;
1612
1613        if (newsize <= conf->pool_size)
1614                return 0; /* never bother to shrink */
1615
1616        err = md_allow_write(conf->mddev);
1617        if (err)
1618                return err;
1619
1620        /* Step 1 */
1621        sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1622                               sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1623                               0, 0, NULL);
1624        if (!sc)
1625                return -ENOMEM;
1626
1627        for (i = conf->max_nr_stripes; i; i--) {
1628                nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1629                if (!nsh)
1630                        break;
1631
1632                nsh->raid_conf = conf;
1633                #ifdef CONFIG_MULTICORE_RAID456
1634                init_waitqueue_head(&nsh->ops.wait_for_ops);
1635                #endif
1636                spin_lock_init(&nsh->stripe_lock);
1637
1638                list_add(&nsh->lru, &newstripes);
1639        }
1640        if (i) {
1641                /* didn't get enough, give up */
1642                while (!list_empty(&newstripes)) {
1643                        nsh = list_entry(newstripes.next, struct stripe_head, lru);
1644                        list_del(&nsh->lru);
1645                        kmem_cache_free(sc, nsh);
1646                }
1647                kmem_cache_destroy(sc);
1648                return -ENOMEM;
1649        }
1650        /* Step 2 - Must use GFP_NOIO now.
1651         * OK, we have enough stripes, start collecting inactive
1652         * stripes and copying them over
1653         */
1654        list_for_each_entry(nsh, &newstripes, lru) {
1655                spin_lock_irq(&conf->device_lock);
1656                wait_event_lock_irq(conf->wait_for_stripe,
1657                                    !list_empty(&conf->inactive_list),
1658                                    conf->device_lock);
1659                osh = get_free_stripe(conf);
1660                spin_unlock_irq(&conf->device_lock);
1661                atomic_set(&nsh->count, 1);
1662                for(i=0; i<conf->pool_size; i++)
1663                        nsh->dev[i].page = osh->dev[i].page;
1664                for( ; i<newsize; i++)
1665                        nsh->dev[i].page = NULL;
1666                kmem_cache_free(conf->slab_cache, osh);
1667        }
1668        kmem_cache_destroy(conf->slab_cache);
1669
1670        /* Step 3.
1671         * At this point, we are holding all the stripes so the array
1672         * is completely stalled, so now is a good time to resize
1673         * conf->disks and the scribble region
1674         */
1675        ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1676        if (ndisks) {
1677                for (i=0; i<conf->raid_disks; i++)
1678                        ndisks[i] = conf->disks[i];
1679                kfree(conf->disks);
1680                conf->disks = ndisks;
1681        } else
1682                err = -ENOMEM;
1683
1684        get_online_cpus();
1685        conf->scribble_len = scribble_len(newsize);
1686        for_each_present_cpu(cpu) {
1687                struct raid5_percpu *percpu;
1688                void *scribble;
1689
1690                percpu = per_cpu_ptr(conf->percpu, cpu);
1691                scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1692
1693                if (scribble) {
1694                        kfree(percpu->scribble);
1695                        percpu->scribble = scribble;
1696                } else {
1697                        err = -ENOMEM;
1698                        break;
1699                }
1700        }
1701        put_online_cpus();
1702
1703        /* Step 4, return new stripes to service */
1704        while(!list_empty(&newstripes)) {
1705                nsh = list_entry(newstripes.next, struct stripe_head, lru);
1706                list_del_init(&nsh->lru);
1707
1708                for (i=conf->raid_disks; i < newsize; i++)
1709                        if (nsh->dev[i].page == NULL) {
1710                                struct page *p = alloc_page(GFP_NOIO);
1711                                nsh->dev[i].page = p;
1712                                if (!p)
1713                                        err = -ENOMEM;
1714                        }
1715                release_stripe(nsh);
1716        }
1717        /* critical section pass, GFP_NOIO no longer needed */
1718
1719        conf->slab_cache = sc;
1720        conf->active_name = 1-conf->active_name;
1721        conf->pool_size = newsize;
1722        return err;
1723}
1724
1725static int drop_one_stripe(struct r5conf *conf)
1726{
1727        struct stripe_head *sh;
1728
1729        spin_lock_irq(&conf->device_lock);
1730        sh = get_free_stripe(conf);
1731        spin_unlock_irq(&conf->device_lock);
1732        if (!sh)
1733                return 0;
1734        BUG_ON(atomic_read(&sh->count));
1735        shrink_buffers(sh);
1736        kmem_cache_free(conf->slab_cache, sh);
1737        atomic_dec(&conf->active_stripes);
1738        return 1;
1739}
1740
1741static void shrink_stripes(struct r5conf *conf)
1742{
1743        while (drop_one_stripe(conf))
1744                ;
1745
1746        if (conf->slab_cache)
1747                kmem_cache_destroy(conf->slab_cache);
1748        conf->slab_cache = NULL;
1749}
1750
1751static void raid5_end_read_request(struct bio * bi, int error)
1752{
1753        struct stripe_head *sh = bi->bi_private;
1754        struct r5conf *conf = sh->raid_conf;
1755        int disks = sh->disks, i;
1756        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1757        char b[BDEVNAME_SIZE];
1758        struct md_rdev *rdev = NULL;
1759        sector_t s;
1760
1761        for (i=0 ; i<disks; i++)
1762                if (bi == &sh->dev[i].req)
1763                        break;
1764
1765        pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1766                (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1767                uptodate);
1768        if (i == disks) {
1769                BUG();
1770                return;
1771        }
1772        if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1773                /* If replacement finished while this request was outstanding,
1774                 * 'replacement' might be NULL already.
1775                 * In that case it moved down to 'rdev'.
1776                 * rdev is not removed until all requests are finished.
1777                 */
1778                rdev = conf->disks[i].replacement;
1779        if (!rdev)
1780                rdev = conf->disks[i].rdev;
1781
1782        if (use_new_offset(conf, sh))
1783                s = sh->sector + rdev->new_data_offset;
1784        else
1785                s = sh->sector + rdev->data_offset;
1786        if (uptodate) {
1787                set_bit(R5_UPTODATE, &sh->dev[i].flags);
1788                if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1789                        /* Note that this cannot happen on a
1790                         * replacement device.  We just fail those on
1791                         * any error
1792                         */
1793                        printk_ratelimited(
1794                                KERN_INFO
1795                                "md/raid:%s: read error corrected"
1796                                " (%lu sectors at %llu on %s)\n",
1797                                mdname(conf->mddev), STRIPE_SECTORS,
1798                                (unsigned long long)s,
1799                                bdevname(rdev->bdev, b));
1800                        atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1801                        clear_bit(R5_ReadError, &sh->dev[i].flags);
1802                        clear_bit(R5_ReWrite, &sh->dev[i].flags);
1803                } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
1804                        clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1805
1806                if (atomic_read(&rdev->read_errors))
1807                        atomic_set(&rdev->read_errors, 0);
1808        } else {
1809                const char *bdn = bdevname(rdev->bdev, b);
1810                int retry = 0;
1811                int set_bad = 0;
1812
1813                clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1814                atomic_inc(&rdev->read_errors);
1815                if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1816                        printk_ratelimited(
1817                                KERN_WARNING
1818                                "md/raid:%s: read error on replacement device "
1819                                "(sector %llu on %s).\n",
1820                                mdname(conf->mddev),
1821                                (unsigned long long)s,
1822                                bdn);
1823                else if (conf->mddev->degraded >= conf->max_degraded) {
1824                        set_bad = 1;
1825                        printk_ratelimited(
1826                                KERN_WARNING
1827                                "md/raid:%s: read error not correctable "
1828                                "(sector %llu on %s).\n",
1829                                mdname(conf->mddev),
1830                                (unsigned long long)s,
1831                                bdn);
1832                } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
1833                        /* Oh, no!!! */
1834                        set_bad = 1;
1835                        printk_ratelimited(
1836                                KERN_WARNING
1837                                "md/raid:%s: read error NOT corrected!! "
1838                                "(sector %llu on %s).\n",
1839                                mdname(conf->mddev),
1840                                (unsigned long long)s,
1841                                bdn);
1842                } else if (atomic_read(&rdev->read_errors)
1843                         > conf->max_nr_stripes)
1844                        printk(KERN_WARNING
1845                               "md/raid:%s: Too many read errors, failing device %s.\n",
1846                               mdname(conf->mddev), bdn);
1847                else
1848                        retry = 1;
1849                if (retry)
1850                        if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
1851                                set_bit(R5_ReadError, &sh->dev[i].flags);
1852                                clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1853                        } else
1854                                set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1855                else {
1856                        clear_bit(R5_ReadError, &sh->dev[i].flags);
1857                        clear_bit(R5_ReWrite, &sh->dev[i].flags);
1858                        if (!(set_bad
1859                              && test_bit(In_sync, &rdev->flags)
1860                              && rdev_set_badblocks(
1861                                      rdev, sh->sector, STRIPE_SECTORS, 0)))
1862                                md_error(conf->mddev, rdev);
1863                }
1864        }
1865        rdev_dec_pending(rdev, conf->mddev);
1866        clear_bit(R5_LOCKED, &sh->dev[i].flags);
1867        set_bit(STRIPE_HANDLE, &sh->state);
1868        release_stripe(sh);
1869}
1870
1871static void raid5_end_write_request(struct bio *bi, int error)
1872{
1873        struct stripe_head *sh = bi->bi_private;
1874        struct r5conf *conf = sh->raid_conf;
1875        int disks = sh->disks, i;
1876        struct md_rdev *uninitialized_var(rdev);
1877        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1878        sector_t first_bad;
1879        int bad_sectors;
1880        int replacement = 0;
1881
1882        for (i = 0 ; i < disks; i++) {
1883                if (bi == &sh->dev[i].req) {
1884                        rdev = conf->disks[i].rdev;
1885                        break;
1886                }
1887                if (bi == &sh->dev[i].rreq) {
1888                        rdev = conf->disks[i].replacement;
1889                        if (rdev)
1890                                replacement = 1;
1891                        else
1892                                /* rdev was removed and 'replacement'
1893                                 * replaced it.  rdev is not removed
1894                                 * until all requests are finished.
1895                                 */
1896                                rdev = conf->disks[i].rdev;
1897                        break;
1898                }
1899        }
1900        pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1901                (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1902                uptodate);
1903        if (i == disks) {
1904                BUG();
1905                return;
1906        }
1907
1908        if (replacement) {
1909                if (!uptodate)
1910                        md_error(conf->mddev, rdev);
1911                else if (is_badblock(rdev, sh->sector,
1912                                     STRIPE_SECTORS,
1913                                     &first_bad, &bad_sectors))
1914                        set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
1915        } else {
1916                if (!uptodate) {
1917                        set_bit(WriteErrorSeen, &rdev->flags);
1918                        set_bit(R5_WriteError, &sh->dev[i].flags);
1919                        if (!test_and_set_bit(WantReplacement, &rdev->flags))
1920                                set_bit(MD_RECOVERY_NEEDED,
1921                                        &rdev->mddev->recovery);
1922                } else if (is_badblock(rdev, sh->sector,
1923                                       STRIPE_SECTORS,
1924                                       &first_bad, &bad_sectors))
1925                        set_bit(R5_MadeGood, &sh->dev[i].flags);
1926        }
1927        rdev_dec_pending(rdev, conf->mddev);
1928
1929        if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
1930                clear_bit(R5_LOCKED, &sh->dev[i].flags);
1931        set_bit(STRIPE_HANDLE, &sh->state);
1932        release_stripe(sh);
1933}
1934
1935static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1936        
1937static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1938{
1939        struct r5dev *dev = &sh->dev[i];
1940
1941        bio_init(&dev->req);
1942        dev->req.bi_io_vec = &dev->vec;
1943        dev->req.bi_vcnt++;
1944        dev->req.bi_max_vecs++;
1945        dev->req.bi_private = sh;
1946        dev->vec.bv_page = dev->page;
1947
1948        bio_init(&dev->rreq);
1949        dev->rreq.bi_io_vec = &dev->rvec;
1950        dev->rreq.bi_vcnt++;
1951        dev->rreq.bi_max_vecs++;
1952        dev->rreq.bi_private = sh;
1953        dev->rvec.bv_page = dev->page;
1954
1955        dev->flags = 0;
1956        dev->sector = compute_blocknr(sh, i, previous);
1957}
1958
1959static void error(struct mddev *mddev, struct md_rdev *rdev)
1960{
1961        char b[BDEVNAME_SIZE];
1962        struct r5conf *conf = mddev->private;
1963        unsigned long flags;
1964        pr_debug("raid456: error called\n");
1965
1966        spin_lock_irqsave(&conf->device_lock, flags);
1967        clear_bit(In_sync, &rdev->flags);
1968        mddev->degraded = calc_degraded(conf);
1969        spin_unlock_irqrestore(&conf->device_lock, flags);
1970        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1971
1972        set_bit(Blocked, &rdev->flags);
1973        set_bit(Faulty, &rdev->flags);
1974        set_bit(MD_CHANGE_DEVS, &mddev->flags);
1975        printk(KERN_ALERT
1976               "md/raid:%s: Disk failure on %s, disabling device.\n"
1977               "md/raid:%s: Operation continuing on %d devices.\n",
1978               mdname(mddev),
1979               bdevname(rdev->bdev, b),
1980               mdname(mddev),
1981               conf->raid_disks - mddev->degraded);
1982}
1983
1984/*
1985 * Input: a 'big' sector number,
1986 * Output: index of the data and parity disk, and the sector # in them.
1987 */
1988static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
1989                                     int previous, int *dd_idx,
1990                                     struct stripe_head *sh)
1991{
1992        sector_t stripe, stripe2;
1993        sector_t chunk_number;
1994        unsigned int chunk_offset;
1995        int pd_idx, qd_idx;
1996        int ddf_layout = 0;
1997        sector_t new_sector;
1998        int algorithm = previous ? conf->prev_algo
1999                                 : conf->algorithm;
2000        int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2001                                         : conf->chunk_sectors;
2002        int raid_disks = previous ? conf->previous_raid_disks
2003                                  : conf->raid_disks;
2004        int data_disks = raid_disks - conf->max_degraded;
2005
2006        /* First compute the information on this sector */
2007
2008        /*
2009         * Compute the chunk number and the sector offset inside the chunk
2010         */
2011        chunk_offset = sector_div(r_sector, sectors_per_chunk);
2012        chunk_number = r_sector;
2013
2014        /*
2015         * Compute the stripe number
2016         */
2017        stripe = chunk_number;
2018        *dd_idx = sector_div(stripe, data_disks);
2019        stripe2 = stripe;
2020        /*
2021         * Select the parity disk based on the user selected algorithm.
2022         */
2023        pd_idx = qd_idx = -1;
2024        switch(conf->level) {
2025        case 4:
2026                pd_idx = data_disks;
2027                break;
2028        case 5:
2029                switch (algorithm) {
2030                case ALGORITHM_LEFT_ASYMMETRIC:
2031                        pd_idx = data_disks - sector_div(stripe2, raid_disks);
2032                        if (*dd_idx >= pd_idx)
2033                                (*dd_idx)++;
2034                        break;
2035                case ALGORITHM_RIGHT_ASYMMETRIC:
2036                        pd_idx = sector_div(stripe2, raid_disks);
2037                        if (*dd_idx >= pd_idx)
2038                                (*dd_idx)++;
2039                        break;
2040                case ALGORITHM_LEFT_SYMMETRIC:
2041                        pd_idx = data_disks - sector_div(stripe2, raid_disks);
2042                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2043                        break;
2044                case ALGORITHM_RIGHT_SYMMETRIC:
2045                        pd_idx = sector_div(stripe2, raid_disks);
2046                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2047                        break;
2048                case ALGORITHM_PARITY_0:
2049                        pd_idx = 0;
2050                        (*dd_idx)++;
2051                        break;
2052                case ALGORITHM_PARITY_N:
2053                        pd_idx = data_disks;
2054                        break;
2055                default:
2056                        BUG();
2057                }
2058                break;
2059        case 6:
2060
2061                switch (algorithm) {
2062                case ALGORITHM_LEFT_ASYMMETRIC:
2063                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2064                        qd_idx = pd_idx + 1;
2065                        if (pd_idx == raid_disks-1) {
2066                                (*dd_idx)++;    /* Q D D D P */
2067                                qd_idx = 0;
2068                        } else if (*dd_idx >= pd_idx)
2069                                (*dd_idx) += 2; /* D D P Q D */
2070                        break;
2071                case ALGORITHM_RIGHT_ASYMMETRIC:
2072                        pd_idx = sector_div(stripe2, raid_disks);
2073                        qd_idx = pd_idx + 1;
2074                        if (pd_idx == raid_disks-1) {
2075                                (*dd_idx)++;    /* Q D D D P */
2076                                qd_idx = 0;
2077                        } else if (*dd_idx >= pd_idx)
2078                                (*dd_idx) += 2; /* D D P Q D */
2079                        break;
2080                case ALGORITHM_LEFT_SYMMETRIC:
2081                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2082                        qd_idx = (pd_idx + 1) % raid_disks;
2083                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2084                        break;
2085                case ALGORITHM_RIGHT_SYMMETRIC:
2086                        pd_idx = sector_div(stripe2, raid_disks);
2087                        qd_idx = (pd_idx + 1) % raid_disks;
2088                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2089                        break;
2090
2091                case ALGORITHM_PARITY_0:
2092                        pd_idx = 0;
2093                        qd_idx = 1;
2094                        (*dd_idx) += 2;
2095                        break;
2096                case ALGORITHM_PARITY_N:
2097                        pd_idx = data_disks;
2098                        qd_idx = data_disks + 1;
2099                        break;
2100
2101                case ALGORITHM_ROTATING_ZERO_RESTART:
2102                        /* Exactly the same as RIGHT_ASYMMETRIC, but or
2103                         * of blocks for computing Q is different.
2104                         */
2105                        pd_idx = sector_div(stripe2, raid_disks);
2106                        qd_idx = pd_idx + 1;
2107                        if (pd_idx == raid_disks-1) {
2108                                (*dd_idx)++;    /* Q D D D P */
2109                                qd_idx = 0;
2110                        } else if (*dd_idx >= pd_idx)
2111                                (*dd_idx) += 2; /* D D P Q D */
2112                        ddf_layout = 1;
2113                        break;
2114
2115                case ALGORITHM_ROTATING_N_RESTART:
2116                        /* Same a left_asymmetric, by first stripe is
2117                         * D D D P Q  rather than
2118                         * Q D D D P
2119                         */
2120                        stripe2 += 1;
2121                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2122                        qd_idx = pd_idx + 1;
2123                        if (pd_idx == raid_disks-1) {
2124                                (*dd_idx)++;    /* Q D D D P */
2125                                qd_idx = 0;
2126                        } else if (*dd_idx >= pd_idx)
2127                                (*dd_idx) += 2; /* D D P Q D */
2128                        ddf_layout = 1;
2129                        break;
2130
2131                case ALGORITHM_ROTATING_N_CONTINUE:
2132                        /* Same as left_symmetric but Q is before P */
2133                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2134                        qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2135                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2136                        ddf_layout = 1;
2137                        break;
2138
2139                case ALGORITHM_LEFT_ASYMMETRIC_6:
2140                        /* RAID5 left_asymmetric, with Q on last device */
2141                        pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2142                        if (*dd_idx >= pd_idx)
2143                                (*dd_idx)++;
2144                        qd_idx = raid_disks - 1;
2145                        break;
2146
2147                case ALGORITHM_RIGHT_ASYMMETRIC_6:
2148                        pd_idx = sector_div(stripe2, raid_disks-1);
2149                        if (*dd_idx >= pd_idx)
2150                                (*dd_idx)++;
2151                        qd_idx = raid_disks - 1;
2152                        break;
2153
2154                case ALGORITHM_LEFT_SYMMETRIC_6:
2155                        pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2156                        *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2157                        qd_idx = raid_disks - 1;
2158                        break;
2159
2160                case ALGORITHM_RIGHT_SYMMETRIC_6:
2161                        pd_idx = sector_div(stripe2, raid_disks-1);
2162                        *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2163                        qd_idx = raid_disks - 1;
2164                        break;
2165
2166                case ALGORITHM_PARITY_0_6:
2167                        pd_idx = 0;
2168                        (*dd_idx)++;
2169                        qd_idx = raid_disks - 1;
2170                        break;
2171
2172                default:
2173                        BUG();
2174                }
2175                break;
2176        }
2177
2178        if (sh) {
2179                sh->pd_idx = pd_idx;
2180                sh->qd_idx = qd_idx;
2181                sh->ddf_layout = ddf_layout;
2182        }
2183        /*
2184         * Finally, compute the new sector number
2185         */
2186        new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2187        return new_sector;
2188}
2189
2190
2191static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2192{
2193        struct r5conf *conf = sh->raid_conf;
2194        int raid_disks = sh->disks;
2195        int data_disks = raid_disks - conf->max_degraded;
2196        sector_t new_sector = sh->sector, check;
2197        int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2198                                         : conf->chunk_sectors;
2199        int algorithm = previous ? conf->prev_algo
2200                                 : conf->algorithm;
2201        sector_t stripe;
2202        int chunk_offset;
2203        sector_t chunk_number;
2204        int dummy1, dd_idx = i;
2205        sector_t r_sector;
2206        struct stripe_head sh2;
2207
2208
2209        chunk_offset = sector_div(new_sector, sectors_per_chunk);
2210        stripe = new_sector;
2211
2212        if (i == sh->pd_idx)
2213                return 0;
2214        switch(conf->level) {
2215        case 4: break;
2216        case 5:
2217                switch (algorithm) {
2218                case ALGORITHM_LEFT_ASYMMETRIC:
2219                case ALGORITHM_RIGHT_ASYMMETRIC:
2220                        if (i > sh->pd_idx)
2221                                i--;
2222                        break;
2223                case ALGORITHM_LEFT_SYMMETRIC:
2224                case ALGORITHM_RIGHT_SYMMETRIC:
2225                        if (i < sh->pd_idx)
2226                                i += raid_disks;
2227                        i -= (sh->pd_idx + 1);
2228                        break;
2229                case ALGORITHM_PARITY_0:
2230                        i -= 1;
2231                        break;
2232                case ALGORITHM_PARITY_N:
2233                        break;
2234                default:
2235                        BUG();
2236                }
2237                break;
2238        case 6:
2239                if (i == sh->qd_idx)
2240                        return 0; /* It is the Q disk */
2241                switch (algorithm) {
2242                case ALGORITHM_LEFT_ASYMMETRIC:
2243                case ALGORITHM_RIGHT_ASYMMETRIC:
2244                case ALGORITHM_ROTATING_ZERO_RESTART:
2245                case ALGORITHM_ROTATING_N_RESTART:
2246                        if (sh->pd_idx == raid_disks-1)
2247                                i--;    /* Q D D D P */
2248                        else if (i > sh->pd_idx)
2249                                i -= 2; /* D D P Q D */
2250                        break;
2251                case ALGORITHM_LEFT_SYMMETRIC:
2252                case ALGORITHM_RIGHT_SYMMETRIC:
2253                        if (sh->pd_idx == raid_disks-1)
2254                                i--; /* Q D D D P */
2255                        else {
2256                                /* D D P Q D */
2257                                if (i < sh->pd_idx)
2258                                        i += raid_disks;
2259                                i -= (sh->pd_idx + 2);
2260                        }
2261                        break;
2262                case ALGORITHM_PARITY_0:
2263                        i -= 2;
2264                        break;
2265                case ALGORITHM_PARITY_N:
2266                        break;
2267                case ALGORITHM_ROTATING_N_CONTINUE:
2268                        /* Like left_symmetric, but P is before Q */
2269                        if (sh->pd_idx == 0)
2270                                i--;    /* P D D D Q */
2271                        else {
2272                                /* D D Q P D */
2273                                if (i < sh->pd_idx)
2274                                        i += raid_disks;
2275                                i -= (sh->pd_idx + 1);
2276                        }
2277                        break;
2278                case ALGORITHM_LEFT_ASYMMETRIC_6:
2279                case ALGORITHM_RIGHT_ASYMMETRIC_6:
2280                        if (i > sh->pd_idx)
2281                                i--;
2282                        break;
2283                case ALGORITHM_LEFT_SYMMETRIC_6:
2284                case ALGORITHM_RIGHT_SYMMETRIC_6:
2285                        if (i < sh->pd_idx)
2286                                i += data_disks + 1;
2287                        i -= (sh->pd_idx + 1);
2288                        break;
2289                case ALGORITHM_PARITY_0_6:
2290                        i -= 1;
2291                        break;
2292                default:
2293                        BUG();
2294                }
2295                break;
2296        }
2297
2298        chunk_number = stripe * data_disks + i;
2299        r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2300
2301        check = raid5_compute_sector(conf, r_sector,
2302                                     previous, &dummy1, &sh2);
2303        if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2304                || sh2.qd_idx != sh->qd_idx) {
2305                printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2306                       mdname(conf->mddev));
2307                return 0;
2308        }
2309        return r_sector;
2310}
2311
2312
2313static void
2314schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2315                         int rcw, int expand)
2316{
2317        int i, pd_idx = sh->pd_idx, disks = sh->disks;
2318        struct r5conf *conf = sh->raid_conf;
2319        int level = conf->level;
2320
2321        if (rcw) {
2322                /* if we are not expanding this is a proper write request, and
2323                 * there will be bios with new data to be drained into the
2324                 * stripe cache
2325                 */
2326                if (!expand) {
2327                        sh->reconstruct_state = reconstruct_state_drain_run;
2328                        set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2329                } else
2330                        sh->reconstruct_state = reconstruct_state_run;
2331
2332                set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2333
2334                for (i = disks; i--; ) {
2335                        struct r5dev *dev = &sh->dev[i];
2336
2337                        if (dev->towrite) {
2338                                set_bit(R5_LOCKED, &dev->flags);
2339                                set_bit(R5_Wantdrain, &dev->flags);
2340                                if (!expand)
2341                                        clear_bit(R5_UPTODATE, &dev->flags);
2342                                s->locked++;
2343                        }
2344                }
2345                if (s->locked + conf->max_degraded == disks)
2346                        if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2347                                atomic_inc(&conf->pending_full_writes);
2348        } else {
2349                BUG_ON(level == 6);
2350                BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2351                        test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2352
2353                sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2354                set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2355                set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2356                set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2357
2358                for (i = disks; i--; ) {
2359                        struct r5dev *dev = &sh->dev[i];
2360                        if (i == pd_idx)
2361                                continue;
2362
2363                        if (dev->towrite &&
2364                            (test_bit(R5_UPTODATE, &dev->flags) ||
2365                             test_bit(R5_Wantcompute, &dev->flags))) {
2366                                set_bit(R5_Wantdrain, &dev->flags);
2367                                set_bit(R5_LOCKED, &dev->flags);
2368                                clear_bit(R5_UPTODATE, &dev->flags);
2369                                s->locked++;
2370                        }
2371                }
2372        }
2373
2374        /* keep the parity disk(s) locked while asynchronous operations
2375         * are in flight
2376         */
2377        set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2378        clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2379        s->locked++;
2380
2381        if (level == 6) {
2382                int qd_idx = sh->qd_idx;
2383                struct r5dev *dev = &sh->dev[qd_idx];
2384
2385                set_bit(R5_LOCKED, &dev->flags);
2386                clear_bit(R5_UPTODATE, &dev->flags);
2387                s->locked++;
2388        }
2389
2390        pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2391                __func__, (unsigned long long)sh->sector,
2392                s->locked, s->ops_request);
2393}
2394
2395/*
2396 * Each stripe/dev can have one or more bion attached.
2397 * toread/towrite point to the first in a chain.
2398 * The bi_next chain must be in order.
2399 */
2400static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2401{
2402        struct bio **bip;
2403        struct r5conf *conf = sh->raid_conf;
2404        int firstwrite=0;
2405
2406        pr_debug("adding bi b#%llu to stripe s#%llu\n",
2407                (unsigned long long)bi->bi_sector,
2408                (unsigned long long)sh->sector);
2409
2410        /*
2411         * If several bio share a stripe. The bio bi_phys_segments acts as a
2412         * reference count to avoid race. The reference count should already be
2413         * increased before this function is called (for example, in
2414         * make_request()), so other bio sharing this stripe will not free the
2415         * stripe. If a stripe is owned by one stripe, the stripe lock will
2416         * protect it.
2417         */
2418        spin_lock_irq(&sh->stripe_lock);
2419        if (forwrite) {
2420                bip = &sh->dev[dd_idx].towrite;
2421                if (*bip == NULL)
2422                        firstwrite = 1;
2423        } else
2424                bip = &sh->dev[dd_idx].toread;
2425        while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2426                if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
2427                        goto overlap;
2428                bip = & (*bip)->bi_next;
2429        }
2430        if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
2431                goto overlap;
2432
2433        BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2434        if (*bip)
2435                bi->bi_next = *bip;
2436        *bip = bi;
2437        raid5_inc_bi_active_stripes(bi);
2438
2439        if (forwrite) {
2440                /* check if page is covered */
2441                sector_t sector = sh->dev[dd_idx].sector;
2442                for (bi=sh->dev[dd_idx].towrite;
2443                     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2444                             bi && bi->bi_sector <= sector;
2445                     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2446                        if (bi->bi_sector + (bi->bi_size>>9) >= sector)
2447                                sector = bi->bi_sector + (bi->bi_size>>9);
2448                }
2449                if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2450                        set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2451        }
2452
2453        pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2454                (unsigned long long)(*bip)->bi_sector,
2455                (unsigned long long)sh->sector, dd_idx);
2456        spin_unlock_irq(&sh->stripe_lock);
2457
2458        if (conf->mddev->bitmap && firstwrite) {
2459                bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2460                                  STRIPE_SECTORS, 0);
2461                sh->bm_seq = conf->seq_flush+1;
2462                set_bit(STRIPE_BIT_DELAY, &sh->state);
2463        }
2464        return 1;
2465
2466 overlap:
2467        set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2468        spin_unlock_irq(&sh->stripe_lock);
2469        return 0;
2470}
2471
2472static void end_reshape(struct r5conf *conf);
2473
2474static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2475                            struct stripe_head *sh)
2476{
2477        int sectors_per_chunk =
2478                previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2479        int dd_idx;
2480        int chunk_offset = sector_div(stripe, sectors_per_chunk);
2481        int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2482
2483        raid5_compute_sector(conf,
2484                             stripe * (disks - conf->max_degraded)
2485                             *sectors_per_chunk + chunk_offset,
2486                             previous,
2487                             &dd_idx, sh);
2488}
2489
2490static void
2491handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2492                                struct stripe_head_state *s, int disks,
2493                                struct bio **return_bi)
2494{
2495        int i;
2496        for (i = disks; i--; ) {
2497                struct bio *bi;
2498                int bitmap_end = 0;
2499
2500                if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2501                        struct md_rdev *rdev;
2502                        rcu_read_lock();
2503                        rdev = rcu_dereference(conf->disks[i].rdev);
2504                        if (rdev && test_bit(In_sync, &rdev->flags))
2505                                atomic_inc(&rdev->nr_pending);
2506                        else
2507                                rdev = NULL;
2508                        rcu_read_unlock();
2509                        if (rdev) {
2510                                if (!rdev_set_badblocks(
2511                                            rdev,
2512                                            sh->sector,
2513                                            STRIPE_SECTORS, 0))
2514                                        md_error(conf->mddev, rdev);
2515                                rdev_dec_pending(rdev, conf->mddev);
2516                        }
2517                }
2518                spin_lock_irq(&sh->stripe_lock);
2519                /* fail all writes first */
2520                bi = sh->dev[i].towrite;
2521                sh->dev[i].towrite = NULL;
2522                spin_unlock_irq(&sh->stripe_lock);
2523                if (bi)
2524                        bitmap_end = 1;
2525
2526                if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2527                        wake_up(&conf->wait_for_overlap);
2528
2529                while (bi && bi->bi_sector <
2530                        sh->dev[i].sector + STRIPE_SECTORS) {
2531                        struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2532                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
2533                        if (!raid5_dec_bi_active_stripes(bi)) {
2534                                md_write_end(conf->mddev);
2535                                bi->bi_next = *return_bi;
2536                                *return_bi = bi;
2537                        }
2538                        bi = nextbi;
2539                }
2540                if (bitmap_end)
2541                        bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2542                                STRIPE_SECTORS, 0, 0);
2543                bitmap_end = 0;
2544                /* and fail all 'written' */
2545                bi = sh->dev[i].written;
2546                sh->dev[i].written = NULL;
2547                if (bi) bitmap_end = 1;
2548                while (bi && bi->bi_sector <
2549                       sh->dev[i].sector + STRIPE_SECTORS) {
2550                        struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2551                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
2552                        if (!raid5_dec_bi_active_stripes(bi)) {
2553                                md_write_end(conf->mddev);
2554                                bi->bi_next = *return_bi;
2555                                *return_bi = bi;
2556                        }
2557                        bi = bi2;
2558                }
2559
2560                /* fail any reads if this device is non-operational and
2561                 * the data has not reached the cache yet.
2562                 */
2563                if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2564                    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2565                      test_bit(R5_ReadError, &sh->dev[i].flags))) {
2566                        spin_lock_irq(&sh->stripe_lock);
2567                        bi = sh->dev[i].toread;
2568                        sh->dev[i].toread = NULL;
2569                        spin_unlock_irq(&sh->stripe_lock);
2570                        if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2571                                wake_up(&conf->wait_for_overlap);
2572                        while (bi && bi->bi_sector <
2573                               sh->dev[i].sector + STRIPE_SECTORS) {
2574                                struct bio *nextbi =
2575                                        r5_next_bio(bi, sh->dev[i].sector);
2576                                clear_bit(BIO_UPTODATE, &bi->bi_flags);
2577                                if (!raid5_dec_bi_active_stripes(bi)) {
2578                                        bi->bi_next = *return_bi;
2579                                        *return_bi = bi;
2580                                }
2581                                bi = nextbi;
2582                        }
2583                }
2584                if (bitmap_end)
2585                        bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2586                                        STRIPE_SECTORS, 0, 0);
2587                /* If we were in the middle of a write the parity block might
2588                 * still be locked - so just clear all R5_LOCKED flags
2589                 */
2590                clear_bit(R5_LOCKED, &sh->dev[i].flags);
2591        }
2592
2593        if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2594                if (atomic_dec_and_test(&conf->pending_full_writes))
2595                        md_wakeup_thread(conf->mddev->thread);
2596}
2597
2598static void
2599handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2600                   struct stripe_head_state *s)
2601{
2602        int abort = 0;
2603        int i;
2604
2605        clear_bit(STRIPE_SYNCING, &sh->state);
2606        s->syncing = 0;
2607        s->replacing = 0;
2608        /* There is nothing more to do for sync/check/repair.
2609         * Don't even need to abort as that is handled elsewhere
2610         * if needed, and not always wanted e.g. if there is a known
2611         * bad block here.
2612         * For recover/replace we need to record a bad block on all
2613         * non-sync devices, or abort the recovery
2614         */
2615        if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2616                /* During recovery devices cannot be removed, so
2617                 * locking and refcounting of rdevs is not needed
2618                 */
2619                for (i = 0; i < conf->raid_disks; i++) {
2620                        struct md_rdev *rdev = conf->disks[i].rdev;
2621                        if (rdev
2622                            && !test_bit(Faulty, &rdev->flags)
2623                            && !test_bit(In_sync, &rdev->flags)
2624                            && !rdev_set_badblocks(rdev, sh->sector,
2625                                                   STRIPE_SECTORS, 0))
2626                                abort = 1;
2627                        rdev = conf->disks[i].replacement;
2628                        if (rdev
2629                            && !test_bit(Faulty, &rdev->flags)
2630                            && !test_bit(In_sync, &rdev->flags)
2631                            && !rdev_set_badblocks(rdev, sh->sector,
2632                                                   STRIPE_SECTORS, 0))
2633                                abort = 1;
2634                }
2635                if (abort)
2636                        conf->recovery_disabled =
2637                                conf->mddev->recovery_disabled;
2638        }
2639        md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2640}
2641
2642static int want_replace(struct stripe_head *sh, int disk_idx)
2643{
2644        struct md_rdev *rdev;
2645        int rv = 0;
2646        /* Doing recovery so rcu locking not required */
2647        rdev = sh->raid_conf->disks[disk_idx].replacement;
2648        if (rdev
2649            && !test_bit(Faulty, &rdev->flags)
2650            && !test_bit(In_sync, &rdev->flags)
2651            && (rdev->recovery_offset <= sh->sector
2652                || rdev->mddev->recovery_cp <= sh->sector))
2653                rv = 1;
2654
2655        return rv;
2656}
2657
2658/* fetch_block - checks the given member device to see if its data needs
2659 * to be read or computed to satisfy a request.
2660 *
2661 * Returns 1 when no more member devices need to be checked, otherwise returns
2662 * 0 to tell the loop in handle_stripe_fill to continue
2663 */
2664static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2665                       int disk_idx, int disks)
2666{
2667        struct r5dev *dev = &sh->dev[disk_idx];
2668        struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2669                                  &sh->dev[s->failed_num[1]] };
2670
2671        /* is the data in this block needed, and can we get it? */
2672        if (!test_bit(R5_LOCKED, &dev->flags) &&
2673            !test_bit(R5_UPTODATE, &dev->flags) &&
2674            (dev->toread ||
2675             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2676             s->syncing || s->expanding ||
2677             (s->replacing && want_replace(sh, disk_idx)) ||
2678             (s->failed >= 1 && fdev[0]->toread) ||
2679             (s->failed >= 2 && fdev[1]->toread) ||
2680             (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2681              !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2682             (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
2683                /* we would like to get this block, possibly by computing it,
2684                 * otherwise read it if the backing disk is insync
2685                 */
2686                BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2687                BUG_ON(test_bit(R5_Wantread, &dev->flags));
2688                if ((s->uptodate == disks - 1) &&
2689                    (s->failed && (disk_idx == s->failed_num[0] ||
2690                                   disk_idx == s->failed_num[1]))) {
2691                        /* have disk failed, and we're requested to fetch it;
2692                         * do compute it
2693                         */
2694                        pr_debug("Computing stripe %llu block %d\n",
2695                               (unsigned long long)sh->sector, disk_idx);
2696                        set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2697                        set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2698                        set_bit(R5_Wantcompute, &dev->flags);
2699                        sh->ops.target = disk_idx;
2700                        sh->ops.target2 = -1; /* no 2nd target */
2701                        s->req_compute = 1;
2702                        /* Careful: from this point on 'uptodate' is in the eye
2703                         * of raid_run_ops which services 'compute' operations
2704                         * before writes. R5_Wantcompute flags a block that will
2705                         * be R5_UPTODATE by the time it is needed for a
2706                         * subsequent operation.
2707                         */
2708                        s->uptodate++;
2709                        return 1;
2710                } else if (s->uptodate == disks-2 && s->failed >= 2) {
2711                        /* Computing 2-failure is *very* expensive; only
2712                         * do it if failed >= 2
2713                         */
2714                        int other;
2715                        for (other = disks; other--; ) {
2716                                if (other == disk_idx)
2717                                        continue;
2718                                if (!test_bit(R5_UPTODATE,
2719                                      &sh->dev[other].flags))
2720                                        break;
2721                        }
2722                        BUG_ON(other < 0);
2723                        pr_debug("Computing stripe %llu blocks %d,%d\n",
2724                               (unsigned long long)sh->sector,
2725                               disk_idx, other);
2726                        set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2727                        set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2728                        set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2729                        set_bit(R5_Wantcompute, &sh->dev[other].flags);
2730                        sh->ops.target = disk_idx;
2731                        sh->ops.target2 = other;
2732                        s->uptodate += 2;
2733                        s->req_compute = 1;
2734                        return 1;
2735                } else if (test_bit(R5_Insync, &dev->flags)) {
2736                        set_bit(R5_LOCKED, &dev->flags);
2737                        set_bit(R5_Wantread, &dev->flags);
2738                        s->locked++;
2739                        pr_debug("Reading block %d (sync=%d)\n",
2740                                disk_idx, s->syncing);
2741                }
2742        }
2743
2744        return 0;
2745}
2746
2747/**
2748 * handle_stripe_fill - read or compute data to satisfy pending requests.
2749 */
2750static void handle_stripe_fill(struct stripe_head *sh,
2751                               struct stripe_head_state *s,
2752                               int disks)
2753{
2754        int i;
2755
2756        /* look for blocks to read/compute, skip this if a compute
2757         * is already in flight, or if the stripe contents are in the
2758         * midst of changing due to a write
2759         */
2760        if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2761            !sh->reconstruct_state)
2762                for (i = disks; i--; )
2763                        if (fetch_block(sh, s, i, disks))
2764                                break;
2765        set_bit(STRIPE_HANDLE, &sh->state);
2766}
2767
2768
2769/* handle_stripe_clean_event
2770 * any written block on an uptodate or failed drive can be returned.
2771 * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2772 * never LOCKED, so we don't need to test 'failed' directly.
2773 */
2774static void handle_stripe_clean_event(struct r5conf *conf,
2775        struct stripe_head *sh, int disks, struct bio **return_bi)
2776{
2777        int i;
2778        struct r5dev *dev;
2779
2780        for (i = disks; i--; )
2781                if (sh->dev[i].written) {
2782                        dev = &sh->dev[i];
2783                        if (!test_bit(R5_LOCKED, &dev->flags) &&
2784                            (test_bit(R5_UPTODATE, &dev->flags) ||
2785                             test_bit(R5_Discard, &dev->flags))) {
2786                                /* We can return any write requests */
2787                                struct bio *wbi, *wbi2;
2788                                pr_debug("Return write for disc %d\n", i);
2789                                if (test_and_clear_bit(R5_Discard, &dev->flags))
2790                                        clear_bit(R5_UPTODATE, &dev->flags);
2791                                wbi = dev->written;
2792                                dev->written = NULL;
2793                                while (wbi && wbi->bi_sector <
2794                                        dev->sector + STRIPE_SECTORS) {
2795                                        wbi2 = r5_next_bio(wbi, dev->sector);
2796                                        if (!raid5_dec_bi_active_stripes(wbi)) {
2797                                                md_write_end(conf->mddev);
2798                                                wbi->bi_next = *return_bi;
2799                                                *return_bi = wbi;
2800                                        }
2801                                        wbi = wbi2;
2802                                }
2803                                bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2804                                                STRIPE_SECTORS,
2805                                         !test_bit(STRIPE_DEGRADED, &sh->state),
2806                                                0);
2807                        }
2808                } else if (test_bit(R5_Discard, &sh->dev[i].flags))
2809                        clear_bit(R5_Discard, &sh->dev[i].flags);
2810
2811        if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2812                if (atomic_dec_and_test(&conf->pending_full_writes))
2813                        md_wakeup_thread(conf->mddev->thread);
2814}
2815
2816static void handle_stripe_dirtying(struct r5conf *conf,
2817                                   struct stripe_head *sh,
2818                                   struct stripe_head_state *s,
2819                                   int disks)
2820{
2821        int rmw = 0, rcw = 0, i;
2822        sector_t recovery_cp = conf->mddev->recovery_cp;
2823
2824        /* RAID6 requires 'rcw' in current implementation.
2825         * Otherwise, check whether resync is now happening or should start.
2826         * If yes, then the array is dirty (after unclean shutdown or
2827         * initial creation), so parity in some stripes might be inconsistent.
2828         * In this case, we need to always do reconstruct-write, to ensure
2829         * that in case of drive failure or read-error correction, we
2830         * generate correct data from the parity.
2831         */
2832        if (conf->max_degraded == 2 ||
2833            (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
2834                /* Calculate the real rcw later - for now make it
2835                 * look like rcw is cheaper
2836                 */
2837                rcw = 1; rmw = 2;
2838                pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
2839                         conf->max_degraded, (unsigned long long)recovery_cp,
2840                         (unsigned long long)sh->sector);
2841        } else for (i = disks; i--; ) {
2842                /* would I have to read this buffer for read_modify_write */
2843                struct r5dev *dev = &sh->dev[i];
2844                if ((dev->towrite || i == sh->pd_idx) &&
2845                    !test_bit(R5_LOCKED, &dev->flags) &&
2846                    !(test_bit(R5_UPTODATE, &dev->flags) ||
2847                      test_bit(R5_Wantcompute, &dev->flags))) {
2848                        if (test_bit(R5_Insync, &dev->flags))
2849                                rmw++;
2850                        else
2851                                rmw += 2*disks;  /* cannot read it */
2852                }
2853                /* Would I have to read this buffer for reconstruct_write */
2854                if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2855                    !test_bit(R5_LOCKED, &dev->flags) &&
2856                    !(test_bit(R5_UPTODATE, &dev->flags) ||
2857                    test_bit(R5_Wantcompute, &dev->flags))) {
2858                        if (test_bit(R5_Insync, &dev->flags)) rcw++;
2859                        else
2860                                rcw += 2*disks;
2861                }
2862        }
2863        pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2864                (unsigned long long)sh->sector, rmw, rcw);
2865        set_bit(STRIPE_HANDLE, &sh->state);
2866        if (rmw < rcw && rmw > 0) {
2867                /* prefer read-modify-write, but need to get some data */
2868                blk_add_trace_msg(conf->mddev->queue, "raid5 rmw %llu %d",
2869                                  (unsigned long long)sh->sector, rmw);
2870                for (i = disks; i--; ) {
2871                        struct r5dev *dev = &sh->dev[i];
2872                        if ((dev->towrite || i == sh->pd_idx) &&
2873                            !test_bit(R5_LOCKED, &dev->flags) &&
2874                            !(test_bit(R5_UPTODATE, &dev->flags) ||
2875                            test_bit(R5_Wantcompute, &dev->flags)) &&
2876                            test_bit(R5_Insync, &dev->flags)) {
2877                                if (
2878                                  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2879                                        pr_debug("Read_old block "
2880                                                 "%d for r-m-w\n", i);
2881                                        set_bit(R5_LOCKED, &dev->flags);
2882                                        set_bit(R5_Wantread, &dev->flags);
2883                                        s->locked++;
2884                                } else {
2885                                        set_bit(STRIPE_DELAYED, &sh->state);
2886                                        set_bit(STRIPE_HANDLE, &sh->state);
2887                                }
2888                        }
2889                }
2890        }
2891        if (rcw <= rmw && rcw > 0) {
2892                /* want reconstruct write, but need to get some data */
2893                int qread =0;
2894                rcw = 0;
2895                for (i = disks; i--; ) {
2896                        struct r5dev *dev = &sh->dev[i];
2897                        if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2898                            i != sh->pd_idx && i != sh->qd_idx &&
2899                            !test_bit(R5_LOCKED, &dev->flags) &&
2900                            !(test_bit(R5_UPTODATE, &dev->flags) ||
2901                              test_bit(R5_Wantcompute, &dev->flags))) {
2902                                rcw++;
2903                                if (!test_bit(R5_Insync, &dev->flags))
2904                                        continue; /* it's a failed drive */
2905                                if (
2906                                  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2907                                        pr_debug("Read_old block "
2908                                                "%d for Reconstruct\n", i);
2909                                        set_bit(R5_LOCKED, &dev->flags);
2910                                        set_bit(R5_Wantread, &dev->flags);
2911                                        s->locked++;
2912                                        qread++;
2913                                } else {
2914                                        set_bit(STRIPE_DELAYED, &sh->state);
2915                                        set_bit(STRIPE_HANDLE, &sh->state);
2916                                }
2917                        }
2918                }
2919                if (rcw)
2920                        blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
2921                                          (unsigned long long)sh->sector,
2922                                          rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
2923        }
2924        /* now if nothing is locked, and if we have enough data,
2925         * we can start a write request
2926         */
2927        /* since handle_stripe can be called at any time we need to handle the
2928         * case where a compute block operation has been submitted and then a
2929         * subsequent call wants to start a write request.  raid_run_ops only
2930         * handles the case where compute block and reconstruct are requested
2931         * simultaneously.  If this is not the case then new writes need to be
2932         * held off until the compute completes.
2933         */
2934        if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2935            (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2936            !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2937                schedule_reconstruction(sh, s, rcw == 0, 0);
2938}
2939
2940static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
2941                                struct stripe_head_state *s, int disks)
2942{
2943        struct r5dev *dev = NULL;
2944
2945        set_bit(STRIPE_HANDLE, &sh->state);
2946
2947        switch (sh->check_state) {
2948        case check_state_idle:
2949                /* start a new check operation if there are no failures */
2950                if (s->failed == 0) {
2951                        BUG_ON(s->uptodate != disks);
2952                        sh->check_state = check_state_run;
2953                        set_bit(STRIPE_OP_CHECK, &s->ops_request);
2954                        clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2955                        s->uptodate--;
2956                        break;
2957                }
2958                dev = &sh->dev[s->failed_num[0]];
2959                /* fall through */
2960        case check_state_compute_result:
2961                sh->check_state = check_state_idle;
2962                if (!dev)
2963                        dev = &sh->dev[sh->pd_idx];
2964
2965                /* check that a write has not made the stripe insync */
2966                if (test_bit(STRIPE_INSYNC, &sh->state))
2967                        break;
2968
2969                /* either failed parity check, or recovery is happening */
2970                BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2971                BUG_ON(s->uptodate != disks);
2972
2973                set_bit(R5_LOCKED, &dev->flags);
2974                s->locked++;
2975                set_bit(R5_Wantwrite, &dev->flags);
2976
2977                clear_bit(STRIPE_DEGRADED, &sh->state);
2978                set_bit(STRIPE_INSYNC, &sh->state);
2979                break;
2980        case check_state_run:
2981                break; /* we will be called again upon completion */
2982        case check_state_check_result:
2983                sh->check_state = check_state_idle;
2984
2985                /* if a failure occurred during the check operation, leave
2986                 * STRIPE_INSYNC not set and let the stripe be handled again
2987                 */
2988                if (s->failed)
2989                        break;
2990
2991                /* handle a successful check operation, if parity is correct
2992                 * we are done.  Otherwise update the mismatch count and repair
2993                 * parity if !MD_RECOVERY_CHECK
2994                 */
2995                if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
2996                        /* parity is correct (on disc,
2997                         * not in buffer any more)
2998                         */
2999                        set_bit(STRIPE_INSYNC, &sh->state);
3000                else {
3001                        atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3002                        if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3003                                /* don't try to repair!! */
3004                                set_bit(STRIPE_INSYNC, &sh->state);
3005                        else {
3006                                sh->check_state = check_state_compute_run;
3007                                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3008                                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3009                                set_bit(R5_Wantcompute,
3010                                        &sh->dev[sh->pd_idx].flags);
3011                                sh->ops.target = sh->pd_idx;
3012                                sh->ops.target2 = -1;
3013                                s->uptodate++;
3014                        }
3015                }
3016                break;
3017        case check_state_compute_run:
3018                break;
3019        default:
3020                printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3021                       __func__, sh->check_state,
3022                       (unsigned long long) sh->sector);
3023                BUG();
3024        }
3025}
3026
3027
3028static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3029                                  struct stripe_head_state *s,
3030                                  int disks)
3031{
3032        int pd_idx = sh->pd_idx;
3033        int qd_idx = sh->qd_idx;
3034        struct r5dev *dev;
3035
3036        set_bit(STRIPE_HANDLE, &sh->state);
3037
3038        BUG_ON(s->failed > 2);
3039
3040        /* Want to check and possibly repair P and Q.
3041         * However there could be one 'failed' device, in which
3042         * case we can only check one of them, possibly using the
3043         * other to generate missing data
3044         */
3045
3046        switch (sh->check_state) {
3047        case check_state_idle:
3048                /* start a new check operation if there are < 2 failures */
3049                if (s->failed == s->q_failed) {
3050                        /* The only possible failed device holds Q, so it
3051                         * makes sense to check P (If anything else were failed,
3052                         * we would have used P to recreate it).
3053                         */
3054                        sh->check_state = check_state_run;
3055                }
3056                if (!s->q_failed && s->failed < 2) {
3057                        /* Q is not failed, and we didn't use it to generate
3058                         * anything, so it makes sense to check it
3059                         */
3060                        if (sh->check_state == check_state_run)
3061                                sh->check_state = check_state_run_pq;
3062                        else
3063                                sh->check_state = check_state_run_q;
3064                }
3065
3066                /* discard potentially stale zero_sum_result */
3067                sh->ops.zero_sum_result = 0;
3068
3069                if (sh->check_state == check_state_run) {
3070                        /* async_xor_zero_sum destroys the contents of P */
3071                        clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3072                        s->uptodate--;
3073                }
3074                if (sh->check_state >= check_state_run &&
3075                    sh->check_state <= check_state_run_pq) {
3076                        /* async_syndrome_zero_sum preserves P and Q, so
3077                         * no need to mark them !uptodate here
3078                         */
3079                        set_bit(STRIPE_OP_CHECK, &s->ops_request);
3080                        break;
3081                }
3082
3083                /* we have 2-disk failure */
3084                BUG_ON(s->failed != 2);
3085                /* fall through */
3086        case check_state_compute_result:
3087                sh->check_state = check_state_idle;
3088
3089                /* check that a write has not made the stripe insync */
3090                if (test_bit(STRIPE_INSYNC, &sh->state))
3091                        break;
3092
3093                /* now write out any block on a failed drive,
3094                 * or P or Q if they were recomputed
3095                 */
3096                BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3097                if (s->failed == 2) {
3098                        dev = &sh->dev[s->failed_num[1]];
3099                        s->locked++;
3100                        set_bit(R5_LOCKED, &dev->flags);
3101                        set_bit(R5_Wantwrite, &dev->flags);
3102                }
3103                if (s->failed >= 1) {
3104                        dev = &sh->dev[s->failed_num[0]];
3105                        s->locked++;
3106                        set_bit(R5_LOCKED, &dev->flags);
3107                        set_bit(R5_Wantwrite, &dev->flags);
3108                }
3109                if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3110                        dev = &sh->dev[pd_idx];
3111                        s->locked++;
3112                        set_bit(R5_LOCKED, &dev->flags);
3113                        set_bit(R5_Wantwrite, &dev->flags);
3114                }
3115                if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3116                        dev = &sh->dev[qd_idx];
3117                        s->locked++;
3118                        set_bit(R5_LOCKED, &dev->flags);
3119                        set_bit(R5_Wantwrite, &dev->flags);
3120                }
3121                clear_bit(STRIPE_DEGRADED, &sh->state);
3122
3123                set_bit(STRIPE_INSYNC, &sh->state);
3124                break;
3125        case check_state_run:
3126        case check_state_run_q:
3127        case check_state_run_pq:
3128                break; /* we will be called again upon completion */
3129        case check_state_check_result:
3130                sh->check_state = check_state_idle;
3131
3132                /* handle a successful check operation, if parity is correct
3133                 * we are done.  Otherwise update the mismatch count and repair
3134                 * parity if !MD_RECOVERY_CHECK
3135                 */
3136                if (sh->ops.zero_sum_result == 0) {
3137                        /* both parities are correct */
3138                        if (!s->failed)
3139                                set_bit(STRIPE_INSYNC, &sh->state);
3140                        else {
3141                                /* in contrast to the raid5 case we can validate
3142                                 * parity, but still have a failure to write
3143                                 * back
3144                                 */
3145                                sh->check_state = check_state_compute_result;
3146                                /* Returning at this point means that we may go
3147                                 * off and bring p and/or q uptodate again so
3148                                 * we make sure to check zero_sum_result again
3149                                 * to verify if p or q need writeback
3150                                 */
3151                        }
3152                } else {
3153                        atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3154                        if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3155                                /* don't try to repair!! */
3156                                set_bit(STRIPE_INSYNC, &sh->state);
3157                        else {
3158                                int *target = &sh->ops.target;
3159
3160                                sh->ops.target = -1;
3161                                sh->ops.target2 = -1;
3162                                sh->check_state = check_state_compute_run;
3163                                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3164                                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3165                                if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3166                                        set_bit(R5_Wantcompute,
3167                                                &sh->dev[pd_idx].flags);
3168                                        *target = pd_idx;
3169                                        target = &sh->ops.target2;
3170                                        s->uptodate++;
3171                                }
3172                                if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3173                                        set_bit(R5_Wantcompute,
3174                                                &sh->dev[qd_idx].flags);
3175                                        *target = qd_idx;
3176                                        s->uptodate++;
3177                                }
3178                        }
3179                }
3180                break;
3181        case check_state_compute_run:
3182                break;
3183        default:
3184                printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3185                       __func__, sh->check_state,
3186                       (unsigned long long) sh->sector);
3187                BUG();
3188        }
3189}
3190
3191static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3192{
3193        int i;
3194
3195        /* We have read all the blocks in this stripe and now we need to
3196         * copy some of them into a target stripe for expand.
3197         */
3198        struct dma_async_tx_descriptor *tx = NULL;
3199        clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3200        for (i = 0; i < sh->disks; i++)
3201                if (i != sh->pd_idx && i != sh->qd_idx) {
3202                        int dd_idx, j;
3203                        struct stripe_head *sh2;
3204                        struct async_submit_ctl submit;
3205
3206                        sector_t bn = compute_blocknr(sh, i, 1);
3207                        sector_t s = raid5_compute_sector(conf, bn, 0,
3208                                                          &dd_idx, NULL);
3209                        sh2 = get_active_stripe(conf, s, 0, 1, 1);
3210                        if (sh2 == NULL)
3211                                /* so far only the early blocks of this stripe
3212                                 * have been requested.  When later blocks
3213                                 * get requested, we will try again
3214                                 */
3215                                continue;
3216                        if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3217                           test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3218                                /* must have already done this block */
3219                                release_stripe(sh2);
3220                                continue;
3221                        }
3222
3223                        /* place all the copies on one channel */
3224                        init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3225                        tx = async_memcpy(sh2->dev[dd_idx].page,
3226                                          sh->dev[i].page, 0, 0, STRIPE_SIZE,
3227                                          &submit);
3228
3229                        set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3230                        set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3231                        for (j = 0; j < conf->raid_disks; j++)
3232                                if (j != sh2->pd_idx &&
3233                                    j != sh2->qd_idx &&
3234                                    !test_bit(R5_Expanded, &sh2->dev[j].flags))
3235                                        break;
3236                        if (j == conf->raid_disks) {
3237                                set_bit(STRIPE_EXPAND_READY, &sh2->state);
3238                                set_bit(STRIPE_HANDLE, &sh2->state);
3239                        }
3240                        release_stripe(sh2);
3241
3242                }
3243        /* done submitting copies, wait for them to complete */
3244        async_tx_quiesce(&tx);
3245}
3246
3247/*
3248 * handle_stripe - do things to a stripe.
3249 *
3250 * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3251 * state of various bits to see what needs to be done.
3252 * Possible results:
3253 *    return some read requests which now have data
3254 *    return some write requests which are safely on storage
3255 *    schedule a read on some buffers
3256 *    schedule a write of some buffers
3257 *    return confirmation of parity correctness
3258 *
3259 */
3260
3261static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3262{
3263        struct r5conf *conf = sh->raid_conf;
3264        int disks = sh->disks;
3265        struct r5dev *dev;
3266        int i;
3267        int do_recovery = 0;
3268
3269        memset(s, 0, sizeof(*s));
3270
3271        s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3272        s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3273        s->failed_num[0] = -1;
3274        s->failed_num[1] = -1;
3275
3276        /* Now to look around and see what can be done */
3277        rcu_read_lock();
3278        for (i=disks; i--; ) {
3279                struct md_rdev *rdev;
3280                sector_t first_bad;
3281                int bad_sectors;
3282                int is_bad = 0;
3283
3284                dev = &sh->dev[i];
3285
3286                pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3287                         i, dev->flags,
3288                         dev->toread, dev->towrite, dev->written);
3289                /* maybe we can reply to a read
3290                 *
3291                 * new wantfill requests are only permitted while
3292                 * ops_complete_biofill is guaranteed to be inactive
3293                 */
3294                if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3295                    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3296                        set_bit(R5_Wantfill, &dev->flags);
3297
3298                /* now count some things */
3299                if (test_bit(R5_LOCKED, &dev->flags))
3300                        s->locked++;
3301                if (test_bit(R5_UPTODATE, &dev->flags))
3302                        s->uptodate++;
3303                if (test_bit(R5_Wantcompute, &dev->flags)) {
3304                        s->compute++;
3305                        BUG_ON(s->compute > 2);
3306                }
3307
3308                if (test_bit(R5_Wantfill, &dev->flags))
3309                        s->to_fill++;
3310                else if (dev->toread)
3311                        s->to_read++;
3312                if (dev->towrite) {
3313                        s->to_write++;
3314                        if (!test_bit(R5_OVERWRITE, &dev->flags))
3315                                s->non_overwrite++;
3316                }
3317                if (dev->written)
3318                        s->written++;
3319                /* Prefer to use the replacement for reads, but only
3320                 * if it is recovered enough and has no bad blocks.
3321                 */
3322                rdev = rcu_dereference(conf->disks[i].replacement);
3323                if (rdev && !test_bit(Faulty, &rdev->flags) &&
3324                    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3325                    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3326                                 &first_bad, &bad_sectors))
3327                        set_bit(R5_ReadRepl, &dev->flags);
3328                else {
3329                        if (rdev)
3330                                set_bit(R5_NeedReplace, &dev->flags);
3331                        rdev = rcu_dereference(conf->disks[i].rdev);
3332                        clear_bit(R5_ReadRepl, &dev->flags);
3333                }
3334                if (rdev && test_bit(Faulty, &rdev->flags))
3335                        rdev = NULL;
3336                if (rdev) {
3337                        is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3338                                             &first_bad, &bad_sectors);
3339                        if (s->blocked_rdev == NULL
3340                            && (test_bit(Blocked, &rdev->flags)
3341                                || is_bad < 0)) {
3342                                if (is_bad < 0)
3343                                        set_bit(BlockedBadBlocks,
3344                                                &rdev->flags);
3345                                s->blocked_rdev = rdev;
3346                                atomic_inc(&rdev->nr_pending);
3347                        }
3348                }
3349                clear_bit(R5_Insync, &dev->flags);
3350                if (!rdev)
3351                        /* Not in-sync */;
3352                else if (is_bad) {
3353                        /* also not in-sync */
3354                        if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3355                            test_bit(R5_UPTODATE, &dev->flags)) {
3356                                /* treat as in-sync, but with a read error
3357                                 * which we can now try to correct
3358                                 */
3359                                set_bit(R5_Insync, &dev->flags);
3360                                set_bit(R5_ReadError, &dev->flags);
3361                        }
3362                } else if (test_bit(In_sync, &rdev->flags))
3363                        set_bit(R5_Insync, &dev->flags);
3364                else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3365                        /* in sync if before recovery_offset */
3366                        set_bit(R5_Insync, &dev->flags);
3367                else if (test_bit(R5_UPTODATE, &dev->flags) &&
3368                         test_bit(R5_Expanded, &dev->flags))
3369                        /* If we've reshaped into here, we assume it is Insync.
3370                         * We will shortly update recovery_offset to make
3371                         * it official.
3372                         */
3373                        set_bit(R5_Insync, &dev->flags);
3374
3375                if (rdev && test_bit(R5_WriteError, &dev->flags)) {
3376                        /* This flag does not apply to '.replacement'
3377                         * only to .rdev, so make sure to check that*/
3378                        struct md_rdev *rdev2 = rcu_dereference(
3379                                conf->disks[i].rdev);
3380                        if (rdev2 == rdev)
3381                                clear_bit(R5_Insync, &dev->flags);
3382                        if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3383                                s->handle_bad_blocks = 1;
3384                                atomic_inc(&rdev2->nr_pending);
3385                        } else
3386                                clear_bit(R5_WriteError, &dev->flags);
3387                }
3388                if (rdev && test_bit(R5_MadeGood, &dev->flags)) {
3389                        /* This flag does not apply to '.replacement'
3390                         * only to .rdev, so make sure to check that*/
3391                        struct md_rdev *rdev2 = rcu_dereference(
3392                                conf->disks[i].rdev);
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_MadeGood, &dev->flags);
3398                }
3399                if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3400                        struct md_rdev *rdev2 = rcu_dereference(
3401                                conf->disks[i].replacement);
3402                        if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3403                                s->handle_bad_blocks = 1;
3404                                atomic_inc(&rdev2->nr_pending);
3405                        } else
3406                                clear_bit(R5_MadeGoodRepl, &dev->flags);
3407                }
3408                if (!test_bit(R5_Insync, &dev->flags)) {
3409                        /* The ReadError flag will just be confusing now */
3410                        clear_bit(R5_ReadError, &dev->flags);
3411                        clear_bit(R5_ReWrite, &dev->flags);
3412                }
3413                if (test_bit(R5_ReadError, &dev->flags))
3414                        clear_bit(R5_Insync, &dev->flags);
3415                if (!test_bit(R5_Insync, &dev->flags)) {
3416                        if (s->failed < 2)
3417                                s->failed_num[s->failed] = i;
3418                        s->failed++;
3419                        if (rdev && !test_bit(Faulty, &rdev->flags))
3420                                do_recovery = 1;
3421                }
3422        }
3423        if (test_bit(STRIPE_SYNCING, &sh->state)) {
3424                /* If there is a failed device being replaced,
3425                 *     we must be recovering.
3426                 * else if we are after recovery_cp, we must be syncing
3427                 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3428                 * else we can only be replacing
3429                 * sync and recovery both need to read all devices, and so
3430                 * use the same flag.
3431                 */
3432                if (do_recovery ||
3433                    sh->sector >= conf->mddev->recovery_cp ||
3434                    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3435                        s->syncing = 1;
3436                else
3437                        s->replacing = 1;
3438        }
3439        rcu_read_unlock();
3440}
3441
3442static void handle_stripe(struct stripe_head *sh)
3443{
3444        struct stripe_head_state s;
3445        struct r5conf *conf = sh->raid_conf;
3446        int i;
3447        int prexor;
3448        int disks = sh->disks;
3449        struct r5dev *pdev, *qdev;
3450
3451        clear_bit(STRIPE_HANDLE, &sh->state);
3452        if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3453                /* already being handled, ensure it gets handled
3454                 * again when current action finishes */
3455                set_bit(STRIPE_HANDLE, &sh->state);
3456                return;
3457        }
3458
3459        if (test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3460                set_bit(STRIPE_SYNCING, &sh->state);
3461                clear_bit(STRIPE_INSYNC, &sh->state);
3462        }
3463        clear_bit(STRIPE_DELAYED, &sh->state);
3464
3465        pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3466                "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3467               (unsigned long long)sh->sector, sh->state,
3468               atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3469               sh->check_state, sh->reconstruct_state);
3470
3471        analyse_stripe(sh, &s);
3472
3473        if (s.handle_bad_blocks) {
3474                set_bit(STRIPE_HANDLE, &sh->state);
3475                goto finish;
3476        }
3477
3478        if (unlikely(s.blocked_rdev)) {
3479                if (s.syncing || s.expanding || s.expanded ||
3480                    s.replacing || s.to_write || s.written) {
3481                        set_bit(STRIPE_HANDLE, &sh->state);
3482                        goto finish;
3483                }
3484                /* There is nothing for the blocked_rdev to block */
3485                rdev_dec_pending(s.blocked_rdev, conf->mddev);
3486                s.blocked_rdev = NULL;
3487        }
3488
3489        if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3490                set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3491                set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3492        }
3493
3494        pr_debug("locked=%d uptodate=%d to_read=%d"
3495               " to_write=%d failed=%d failed_num=%d,%d\n",
3496               s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3497               s.failed_num[0], s.failed_num[1]);
3498        /* check if the array has lost more than max_degraded devices and,
3499         * if so, some requests might need to be failed.
3500         */
3501        if (s.failed > conf->max_degraded) {
3502                sh->check_state = 0;
3503                sh->reconstruct_state = 0;
3504                if (s.to_read+s.to_write+s.written)
3505                        handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3506                if (s.syncing + s.replacing)
3507                        handle_failed_sync(conf, sh, &s);
3508        }
3509
3510        /* Now we check to see if any write operations have recently
3511         * completed
3512         */
3513        prexor = 0;
3514        if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3515                prexor = 1;
3516        if (sh->reconstruct_state == reconstruct_state_drain_result ||
3517            sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3518                sh->reconstruct_state = reconstruct_state_idle;
3519
3520                /* All the 'written' buffers and the parity block are ready to
3521                 * be written back to disk
3522                 */
3523                BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3524                       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3525                BUG_ON(sh->qd_idx >= 0 &&
3526                       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3527                       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3528                for (i = disks; i--; ) {
3529                        struct r5dev *dev = &sh->dev[i];
3530                        if (test_bit(R5_LOCKED, &dev->flags) &&
3531                                (i == sh->pd_idx || i == sh->qd_idx ||
3532                                 dev->written)) {
3533                                pr_debug("Writing block %d\n", i);
3534                                set_bit(R5_Wantwrite, &dev->flags);
3535                                if (prexor)
3536                                        continue;
3537                                if (!test_bit(R5_Insync, &dev->flags) ||
3538                                    ((i == sh->pd_idx || i == sh->qd_idx)  &&
3539                                     s.failed == 0))
3540                                        set_bit(STRIPE_INSYNC, &sh->state);
3541                        }
3542                }
3543                if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3544                        s.dec_preread_active = 1;
3545        }
3546
3547        /*
3548         * might be able to return some write requests if the parity blocks
3549         * are safe, or on a failed drive
3550         */
3551        pdev = &sh->dev[sh->pd_idx];
3552        s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3553                || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3554        qdev = &sh->dev[sh->qd_idx];
3555        s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3556                || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3557                || conf->level < 6;
3558
3559        if (s.written &&
3560            (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3561                             && !test_bit(R5_LOCKED, &pdev->flags)
3562                             && (test_bit(R5_UPTODATE, &pdev->flags) ||
3563                                 test_bit(R5_Discard, &pdev->flags))))) &&
3564            (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3565                             && !test_bit(R5_LOCKED, &qdev->flags)
3566                             && (test_bit(R5_UPTODATE, &qdev->flags) ||
3567                                 test_bit(R5_Discard, &qdev->flags))))))
3568                handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3569
3570        /* Now we might consider reading some blocks, either to check/generate
3571         * parity, or to satisfy requests
3572         * or to load a block that is being partially written.
3573         */
3574        if (s.to_read || s.non_overwrite
3575            || (conf->level == 6 && s.to_write && s.failed)
3576            || (s.syncing && (s.uptodate + s.compute < disks))
3577            || s.replacing
3578            || s.expanding)
3579                handle_stripe_fill(sh, &s, disks);
3580
3581        /* Now to consider new write requests and what else, if anything
3582         * should be read.  We do not handle new writes when:
3583         * 1/ A 'write' operation (copy+xor) is already in flight.
3584         * 2/ A 'check' operation is in flight, as it may clobber the parity
3585         *    block.
3586         */
3587        if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3588                handle_stripe_dirtying(conf, sh, &s, disks);
3589
3590        /* maybe we need to check and possibly fix the parity for this stripe
3591         * Any reads will already have been scheduled, so we just see if enough
3592         * data is available.  The parity check is held off while parity
3593         * dependent operations are in flight.
3594         */
3595        if (sh->check_state ||
3596            (s.syncing && s.locked == 0 &&
3597             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3598             !test_bit(STRIPE_INSYNC, &sh->state))) {
3599                if (conf->level == 6)
3600                        handle_parity_checks6(conf, sh, &s, disks);
3601                else
3602                        handle_parity_checks5(conf, sh, &s, disks);
3603        }
3604
3605        if (s.replacing && s.locked == 0
3606            && !test_bit(STRIPE_INSYNC, &sh->state)) {
3607                /* Write out to replacement devices where possible */
3608                for (i = 0; i < conf->raid_disks; i++)
3609                        if (test_bit(R5_UPTODATE, &sh->dev[i].flags) &&
3610                            test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3611                                set_bit(R5_WantReplace, &sh->dev[i].flags);
3612                                set_bit(R5_LOCKED, &sh->dev[i].flags);
3613                                s.locked++;
3614                        }
3615                set_bit(STRIPE_INSYNC, &sh->state);
3616        }
3617        if ((s.syncing || s.replacing) && s.locked == 0 &&
3618            test_bit(STRIPE_INSYNC, &sh->state)) {
3619                md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3620                clear_bit(STRIPE_SYNCING, &sh->state);
3621        }
3622
3623        /* If the failed drives are just a ReadError, then we might need
3624         * to progress the repair/check process
3625         */
3626        if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3627                for (i = 0; i < s.failed; i++) {
3628                        struct r5dev *dev = &sh->dev[s.failed_num[i]];
3629                        if (test_bit(R5_ReadError, &dev->flags)
3630                            && !test_bit(R5_LOCKED, &dev->flags)
3631                            && test_bit(R5_UPTODATE, &dev->flags)
3632                                ) {
3633                                if (!test_bit(R5_ReWrite, &dev->flags)) {
3634                                        set_bit(R5_Wantwrite, &dev->flags);
3635                                        set_bit(R5_ReWrite, &dev->flags);
3636                                        set_bit(R5_LOCKED, &dev->flags);
3637                                        s.locked++;
3638                                } else {
3639                                        /* let's read it back */
3640                                        set_bit(R5_Wantread, &dev->flags);
3641                                        set_bit(R5_LOCKED, &dev->flags);
3642                                        s.locked++;
3643                                }
3644                        }
3645                }
3646
3647
3648        /* Finish reconstruct operations initiated by the expansion process */
3649        if (sh->reconstruct_state == reconstruct_state_result) {
3650                struct stripe_head *sh_src
3651                        = get_active_stripe(conf, sh->sector, 1, 1, 1);
3652                if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3653                        /* sh cannot be written until sh_src has been read.
3654                         * so arrange for sh to be delayed a little
3655                         */
3656                        set_bit(STRIPE_DELAYED, &sh->state);
3657                        set_bit(STRIPE_HANDLE, &sh->state);
3658                        if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3659                                              &sh_src->state))
3660                                atomic_inc(&conf->preread_active_stripes);
3661                        release_stripe(sh_src);
3662                        goto finish;
3663                }
3664                if (sh_src)
3665                        release_stripe(sh_src);
3666
3667                sh->reconstruct_state = reconstruct_state_idle;
3668                clear_bit(STRIPE_EXPANDING, &sh->state);
3669                for (i = conf->raid_disks; i--; ) {
3670                        set_bit(R5_Wantwrite, &sh->dev[i].flags);
3671                        set_bit(R5_LOCKED, &sh->dev[i].flags);
3672                        s.locked++;
3673                }
3674        }
3675
3676        if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3677            !sh->reconstruct_state) {
3678                /* Need to write out all blocks after computing parity */
3679                sh->disks = conf->raid_disks;
3680                stripe_set_idx(sh->sector, conf, 0, sh);
3681                schedule_reconstruction(sh, &s, 1, 1);
3682        } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3683                clear_bit(STRIPE_EXPAND_READY, &sh->state);
3684                atomic_dec(&conf->reshape_stripes);
3685                wake_up(&conf->wait_for_overlap);
3686                md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3687        }
3688
3689        if (s.expanding && s.locked == 0 &&
3690            !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3691                handle_stripe_expansion(conf, sh);
3692
3693finish:
3694        /* wait for this device to become unblocked */
3695        if (unlikely(s.blocked_rdev)) {
3696                if (conf->mddev->external)
3697                        md_wait_for_blocked_rdev(s.blocked_rdev,
3698                                                 conf->mddev);
3699                else
3700                        /* Internal metadata will immediately
3701                         * be written by raid5d, so we don't
3702                         * need to wait here.
3703                         */
3704                        rdev_dec_pending(s.blocked_rdev,
3705                                         conf->mddev);
3706        }
3707
3708        if (s.handle_bad_blocks)
3709                for (i = disks; i--; ) {
3710                        struct md_rdev *rdev;
3711                        struct r5dev *dev = &sh->dev[i];
3712                        if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3713                                /* We own a safe reference to the rdev */
3714                                rdev = conf->disks[i].rdev;
3715                                if (!rdev_set_badblocks(rdev, sh->sector,
3716                                                        STRIPE_SECTORS, 0))
3717                                        md_error(conf->mddev, rdev);
3718                                rdev_dec_pending(rdev, conf->mddev);
3719                        }
3720                        if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3721                                rdev = conf->disks[i].rdev;
3722                                rdev_clear_badblocks(rdev, sh->sector,
3723                                                     STRIPE_SECTORS, 0);
3724                                rdev_dec_pending(rdev, conf->mddev);
3725                        }
3726                        if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
3727                                rdev = conf->disks[i].replacement;
3728                                if (!rdev)
3729                                        /* rdev have been moved down */
3730                                        rdev = conf->disks[i].rdev;
3731                                rdev_clear_badblocks(rdev, sh->sector,
3732                                                     STRIPE_SECTORS, 0);
3733                                rdev_dec_pending(rdev, conf->mddev);
3734                        }
3735                }
3736
3737        if (s.ops_request)
3738                raid_run_ops(sh, s.ops_request);
3739
3740        ops_run_io(sh, &s);
3741
3742        if (s.dec_preread_active) {
3743                /* We delay this until after ops_run_io so that if make_request
3744                 * is waiting on a flush, it won't continue until the writes
3745                 * have actually been submitted.
3746                 */
3747                atomic_dec(&conf->preread_active_stripes);
3748                if (atomic_read(&conf->preread_active_stripes) <
3749                    IO_THRESHOLD)
3750                        md_wakeup_thread(conf->mddev->thread);
3751        }
3752
3753        return_io(s.return_bi);
3754
3755        clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
3756}
3757
3758static void raid5_activate_delayed(struct r5conf *conf)
3759{
3760        if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3761                while (!list_empty(&conf->delayed_list)) {
3762                        struct list_head *l = conf->delayed_list.next;
3763                        struct stripe_head *sh;
3764                        sh = list_entry(l, struct stripe_head, lru);
3765                        list_del_init(l);
3766                        clear_bit(STRIPE_DELAYED, &sh->state);
3767                        if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3768                                atomic_inc(&conf->preread_active_stripes);
3769                        list_add_tail(&sh->lru, &conf->hold_list);
3770                }
3771        }
3772}
3773
3774static void activate_bit_delay(struct r5conf *conf)
3775{
3776        /* device_lock is held */
3777        struct list_head head;
3778        list_add(&head, &conf->bitmap_list);
3779        list_del_init(&conf->bitmap_list);
3780        while (!list_empty(&head)) {
3781                struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3782                list_del_init(&sh->lru);
3783                atomic_inc(&sh->count);
3784                __release_stripe(conf, sh);
3785        }
3786}
3787
3788int md_raid5_congested(struct mddev *mddev, int bits)
3789{
3790        struct r5conf *conf = mddev->private;
3791
3792        /* No difference between reads and writes.  Just check
3793         * how busy the stripe_cache is
3794         */
3795
3796        if (conf->inactive_blocked)
3797                return 1;
3798        if (conf->quiesce)
3799                return 1;
3800        if (list_empty_careful(&conf->inactive_list))
3801                return 1;
3802
3803        return 0;
3804}
3805EXPORT_SYMBOL_GPL(md_raid5_congested);
3806
3807static int raid5_congested(void *data, int bits)
3808{
3809        struct mddev *mddev = data;
3810
3811        return mddev_congested(mddev, bits) ||
3812                md_raid5_congested(mddev, bits);
3813}
3814
3815/* We want read requests to align with chunks where possible,
3816 * but write requests don't need to.
3817 */
3818static int raid5_mergeable_bvec(struct request_queue *q,
3819                                struct bvec_merge_data *bvm,
3820                                struct bio_vec *biovec)
3821{
3822        struct mddev *mddev = q->queuedata;
3823        sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3824        int max;
3825        unsigned int chunk_sectors = mddev->chunk_sectors;
3826        unsigned int bio_sectors = bvm->bi_size >> 9;
3827
3828        if ((bvm->bi_rw & 1) == WRITE)
3829                return biovec->bv_len; /* always allow writes to be mergeable */
3830
3831        if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3832                chunk_sectors = mddev->new_chunk_sectors;
3833        max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3834        if (max < 0) max = 0;
3835        if (max <= biovec->bv_len && bio_sectors == 0)
3836                return biovec->bv_len;
3837        else
3838                return max;
3839}
3840
3841
3842static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
3843{
3844        sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3845        unsigned int chunk_sectors = mddev->chunk_sectors;
3846        unsigned int bio_sectors = bio->bi_size >> 9;
3847
3848        if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3849                chunk_sectors = mddev->new_chunk_sectors;
3850        return  chunk_sectors >=
3851                ((sector & (chunk_sectors - 1)) + bio_sectors);
3852}
3853
3854/*
3855 *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3856 *  later sampled by raid5d.
3857 */
3858static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
3859{
3860        unsigned long flags;
3861
3862        spin_lock_irqsave(&conf->device_lock, flags);
3863
3864        bi->bi_next = conf->retry_read_aligned_list;
3865        conf->retry_read_aligned_list = bi;
3866
3867        spin_unlock_irqrestore(&conf->device_lock, flags);
3868        md_wakeup_thread(conf->mddev->thread);
3869}
3870
3871
3872static struct bio *remove_bio_from_retry(struct r5conf *conf)
3873{
3874        struct bio *bi;
3875
3876        bi = conf->retry_read_aligned;
3877        if (bi) {
3878                conf->retry_read_aligned = NULL;
3879                return bi;
3880        }
3881        bi = conf->retry_read_aligned_list;
3882        if(bi) {
3883                conf->retry_read_aligned_list = bi->bi_next;
3884                bi->bi_next = NULL;
3885                /*
3886                 * this sets the active strip count to 1 and the processed
3887                 * strip count to zero (upper 8 bits)
3888                 */
3889                raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
3890        }
3891
3892        return bi;
3893}
3894
3895
3896/*
3897 *  The "raid5_align_endio" should check if the read succeeded and if it
3898 *  did, call bio_endio on the original bio (having bio_put the new bio
3899 *  first).
3900 *  If the read failed..
3901 */
3902static void raid5_align_endio(struct bio *bi, int error)
3903{
3904        struct bio* raid_bi  = bi->bi_private;
3905        struct mddev *mddev;
3906        struct r5conf *conf;
3907        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3908        struct md_rdev *rdev;
3909
3910        bio_put(bi);
3911
3912        rdev = (void*)raid_bi->bi_next;
3913        raid_bi->bi_next = NULL;
3914        mddev = rdev->mddev;
3915        conf = mddev->private;
3916
3917        rdev_dec_pending(rdev, conf->mddev);
3918
3919        if (!error && uptodate) {
3920                trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
3921                                         raid_bi, 0);
3922                bio_endio(raid_bi, 0);
3923                if (atomic_dec_and_test(&conf->active_aligned_reads))
3924                        wake_up(&conf->wait_for_stripe);
3925                return;
3926        }
3927
3928
3929        pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3930
3931        add_bio_to_retry(raid_bi, conf);
3932}
3933
3934static int bio_fits_rdev(struct bio *bi)
3935{
3936        struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3937
3938        if ((bi->bi_size>>9) > queue_max_sectors(q))
3939                return 0;
3940        blk_recount_segments(q, bi);
3941        if (bi->bi_phys_segments > queue_max_segments(q))
3942                return 0;
3943
3944        if (q->merge_bvec_fn)
3945                /* it's too hard to apply the merge_bvec_fn at this stage,
3946                 * just just give up
3947                 */
3948                return 0;
3949
3950        return 1;
3951}
3952
3953
3954static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
3955{
3956        struct r5conf *conf = mddev->private;
3957        int dd_idx;
3958        struct bio* align_bi;
3959        struct md_rdev *rdev;
3960        sector_t end_sector;
3961
3962        if (!in_chunk_boundary(mddev, raid_bio)) {
3963                pr_debug("chunk_aligned_read : non aligned\n");
3964                return 0;
3965        }
3966        /*
3967         * use bio_clone_mddev to make a copy of the bio
3968         */
3969        align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
3970        if (!align_bi)
3971                return 0;
3972        /*
3973         *   set bi_end_io to a new function, and set bi_private to the
3974         *     original bio.
3975         */
3976        align_bi->bi_end_io  = raid5_align_endio;
3977        align_bi->bi_private = raid_bio;
3978        /*
3979         *      compute position
3980         */
3981        align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
3982                                                    0,
3983                                                    &dd_idx, NULL);
3984
3985        end_sector = align_bi->bi_sector + (align_bi->bi_size >> 9);
3986        rcu_read_lock();
3987        rdev = rcu_dereference(conf->disks[dd_idx].replacement);
3988        if (!rdev || test_bit(Faulty, &rdev->flags) ||
3989            rdev->recovery_offset < end_sector) {
3990                rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3991                if (rdev &&
3992                    (test_bit(Faulty, &rdev->flags) ||
3993                    !(test_bit(In_sync, &rdev->flags) ||
3994                      rdev->recovery_offset >= end_sector)))
3995                        rdev = NULL;
3996        }
3997        if (rdev) {
3998                sector_t first_bad;
3999                int bad_sectors;
4000
4001                atomic_inc(&rdev->nr_pending);
4002                rcu_read_unlock();
4003                raid_bio->bi_next = (void*)rdev;
4004                align_bi->bi_bdev =  rdev->bdev;
4005                align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
4006
4007                if (!bio_fits_rdev(align_bi) ||
4008                    is_badblock(rdev, align_bi->bi_sector, align_bi->bi_size>>9,
4009                                &first_bad, &bad_sectors)) {
4010                        /* too big in some way, or has a known bad block */
4011                        bio_put(align_bi);
4012                        rdev_dec_pending(rdev, mddev);
4013                        return 0;
4014                }
4015
4016                /* No reshape active, so we can trust rdev->data_offset */
4017                align_bi->bi_sector += rdev->data_offset;
4018
4019                spin_lock_irq(&conf->device_lock);
4020                wait_event_lock_irq(conf->wait_for_stripe,
4021                                    conf->quiesce == 0,
4022                                    conf->device_lock);
4023                atomic_inc(&conf->active_aligned_reads);
4024                spin_unlock_irq(&conf->device_lock);
4025
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        trace_block_unplug(mddev->queue, cnt, !from_schedule);
4123        kfree(cb);
4124}
4125
4126static void release_stripe_plug(struct mddev *mddev,
4127                                struct stripe_head *sh)
4128{
4129        struct blk_plug_cb *blk_cb = blk_check_plugged(
4130                raid5_unplug, mddev,
4131                sizeof(struct raid5_plug_cb));
4132        struct raid5_plug_cb *cb;
4133
4134        if (!blk_cb) {
4135                release_stripe(sh);
4136                return;
4137        }
4138
4139        cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4140
4141        if (cb->list.next == NULL)
4142                INIT_LIST_HEAD(&cb->list);
4143
4144        if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4145                list_add_tail(&sh->lru, &cb->list);
4146        else
4147                release_stripe(sh);
4148}
4149
4150static void make_discard_request(struct mddev *mddev, struct bio *bi)
4151{
4152        struct r5conf *conf = mddev->private;
4153        sector_t logical_sector, last_sector;
4154        struct stripe_head *sh;
4155        int remaining;
4156        int stripe_sectors;
4157
4158        if (mddev->reshape_position != MaxSector)
4159                /* Skip discard while reshape is happening */
4160                return;
4161
4162        logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4163        last_sector = bi->bi_sector + (bi->bi_size>>9);
4164
4165        bi->bi_next = NULL;
4166        bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4167
4168        stripe_sectors = conf->chunk_sectors *
4169                (conf->raid_disks - conf->max_degraded);
4170        logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4171                                               stripe_sectors);
4172        sector_div(last_sector, stripe_sectors);
4173
4174        logical_sector *= conf->chunk_sectors;
4175        last_sector *= conf->chunk_sectors;
4176
4177        for (; logical_sector < last_sector;
4178             logical_sector += STRIPE_SECTORS) {
4179                DEFINE_WAIT(w);
4180                int d;
4181        again:
4182                sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4183                prepare_to_wait(&conf->wait_for_overlap, &w,
4184                                TASK_UNINTERRUPTIBLE);
4185                spin_lock_irq(&sh->stripe_lock);
4186                for (d = 0; d < conf->raid_disks; d++) {
4187                        if (d == sh->pd_idx || d == sh->qd_idx)
4188                                continue;
4189                        if (sh->dev[d].towrite || sh->dev[d].toread) {
4190                                set_bit(R5_Overlap, &sh->dev[d].flags);
4191                                spin_unlock_irq(&sh->stripe_lock);
4192                                release_stripe(sh);
4193                                schedule();
4194                                goto again;
4195                        }
4196                }
4197                finish_wait(&conf->wait_for_overlap, &w);
4198                for (d = 0; d < conf->raid_disks; d++) {
4199                        if (d == sh->pd_idx || d == sh->qd_idx)
4200                                continue;
4201                        sh->dev[d].towrite = bi;
4202                        set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4203                        raid5_inc_bi_active_stripes(bi);
4204                }
4205                spin_unlock_irq(&sh->stripe_lock);
4206                if (conf->mddev->bitmap) {
4207                        for (d = 0;
4208                             d < conf->raid_disks - conf->max_degraded;
4209                             d++)
4210                                bitmap_startwrite(mddev->bitmap,
4211                                                  sh->sector,
4212                                                  STRIPE_SECTORS,
4213                                                  0);
4214                        sh->bm_seq = conf->seq_flush + 1;
4215                        set_bit(STRIPE_BIT_DELAY, &sh->state);
4216                }
4217
4218                set_bit(STRIPE_HANDLE, &sh->state);
4219                clear_bit(STRIPE_DELAYED, &sh->state);
4220                if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4221                        atomic_inc(&conf->preread_active_stripes);
4222                release_stripe_plug(mddev, sh);
4223        }
4224
4225        remaining = raid5_dec_bi_active_stripes(bi);
4226        if (remaining == 0) {
4227                md_write_end(mddev);
4228                bio_endio(bi, 0);
4229        }
4230}
4231
4232static void make_request(struct mddev *mddev, struct bio * bi)
4233{
4234        struct r5conf *conf = mddev->private;
4235        int dd_idx;
4236        sector_t new_sector;
4237        sector_t logical_sector, last_sector;
4238        struct stripe_head *sh;
4239        const int rw = bio_data_dir(bi);
4240        int remaining;
4241
4242        if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4243                md_flush_request(mddev, bi);
4244                return;
4245        }
4246
4247        md_write_start(mddev, bi);
4248
4249        if (rw == READ &&
4250             mddev->reshape_position == MaxSector &&
4251             chunk_aligned_read(mddev,bi))
4252                return;
4253
4254        if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4255                make_discard_request(mddev, bi);
4256                return;
4257        }
4258
4259        logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4260        last_sector = bi->bi_sector + (bi->bi_size>>9);
4261        bi->bi_next = NULL;
4262        bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
4263
4264        for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4265                DEFINE_WAIT(w);
4266                int previous;
4267
4268        retry:
4269                previous = 0;
4270                prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4271                if (unlikely(conf->reshape_progress != MaxSector)) {
4272                        /* spinlock is needed as reshape_progress may be
4273                         * 64bit on a 32bit platform, and so it might be
4274                         * possible to see a half-updated value
4275                         * Of course reshape_progress could change after
4276                         * the lock is dropped, so once we get a reference
4277                         * to the stripe that we think it is, we will have
4278                         * to check again.
4279                         */
4280                        spin_lock_irq(&conf->device_lock);
4281                        if (mddev->reshape_backwards
4282                            ? logical_sector < conf->reshape_progress
4283                            : logical_sector >= conf->reshape_progress) {
4284                                previous = 1;
4285                        } else {
4286                                if (mddev->reshape_backwards
4287                                    ? logical_sector < conf->reshape_safe
4288                                    : logical_sector >= conf->reshape_safe) {
4289                                        spin_unlock_irq(&conf->device_lock);
4290                                        schedule();
4291                                        goto retry;
4292                                }
4293                        }
4294                        spin_unlock_irq(&conf->device_lock);
4295                }
4296
4297                new_sector = raid5_compute_sector(conf, logical_sector,
4298                                                  previous,
4299                                                  &dd_idx, NULL);
4300                pr_debug("raid456: make_request, sector %llu logical %llu\n",
4301                        (unsigned long long)new_sector, 
4302                        (unsigned long long)logical_sector);
4303
4304                sh = get_active_stripe(conf, new_sector, previous,
4305                                       (bi->bi_rw&RWA_MASK), 0);
4306                if (sh) {
4307                        if (unlikely(previous)) {
4308                                /* expansion might have moved on while waiting for a
4309                                 * stripe, so we must do the range check again.
4310                                 * Expansion could still move past after this
4311                                 * test, but as we are holding a reference to
4312                                 * 'sh', we know that if that happens,
4313                                 *  STRIPE_EXPANDING will get set and the expansion
4314                                 * won't proceed until we finish with the stripe.
4315                                 */
4316                                int must_retry = 0;
4317                                spin_lock_irq(&conf->device_lock);
4318                                if (mddev->reshape_backwards
4319                                    ? logical_sector >= conf->reshape_progress
4320                                    : logical_sector < conf->reshape_progress)
4321                                        /* mismatch, need to try again */
4322                                        must_retry = 1;
4323                                spin_unlock_irq(&conf->device_lock);
4324                                if (must_retry) {
4325                                        release_stripe(sh);
4326                                        schedule();
4327                                        goto retry;
4328                                }
4329                        }
4330
4331                        if (rw == WRITE &&
4332                            logical_sector >= mddev->suspend_lo &&
4333                            logical_sector < mddev->suspend_hi) {
4334                                release_stripe(sh);
4335                                /* As the suspend_* range is controlled by
4336                                 * userspace, we want an interruptible
4337                                 * wait.
4338                                 */
4339                                flush_signals(current);
4340                                prepare_to_wait(&conf->wait_for_overlap,
4341                                                &w, TASK_INTERRUPTIBLE);
4342                                if (logical_sector >= mddev->suspend_lo &&
4343                                    logical_sector < mddev->suspend_hi)
4344                                        schedule();
4345                                goto retry;
4346                        }
4347
4348                        if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4349                            !add_stripe_bio(sh, bi, dd_idx, rw)) {
4350                                /* Stripe is busy expanding or
4351                                 * add failed due to overlap.  Flush everything
4352                                 * and wait a while
4353                                 */
4354                                md_wakeup_thread(mddev->thread);
4355                                release_stripe(sh);
4356                                schedule();
4357                                goto retry;
4358                        }
4359                        finish_wait(&conf->wait_for_overlap, &w);
4360                        set_bit(STRIPE_HANDLE, &sh->state);
4361                        clear_bit(STRIPE_DELAYED, &sh->state);
4362                        if ((bi->bi_rw & REQ_SYNC) &&
4363                            !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4364                                atomic_inc(&conf->preread_active_stripes);
4365                        release_stripe_plug(mddev, sh);
4366                } else {
4367                        /* cannot get stripe for read-ahead, just give-up */
4368                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
4369                        finish_wait(&conf->wait_for_overlap, &w);
4370                        break;
4371                }
4372        }
4373
4374        remaining = raid5_dec_bi_active_stripes(bi);
4375        if (remaining == 0) {
4376
4377                if ( rw == WRITE )
4378                        md_write_end(mddev);
4379
4380                trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4381                                         bi, 0);
4382                bio_endio(bi, 0);
4383        }
4384}
4385
4386static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4387
4388static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4389{
4390        /* reshaping is quite different to recovery/resync so it is
4391         * handled quite separately ... here.
4392         *
4393         * On each call to sync_request, we gather one chunk worth of
4394         * destination stripes and flag them as expanding.
4395         * Then we find all the source stripes and request reads.
4396         * As the reads complete, handle_stripe will copy the data
4397         * into the destination stripe and release that stripe.
4398         */
4399        struct r5conf *conf = mddev->private;
4400        struct stripe_head *sh;
4401        sector_t first_sector, last_sector;
4402        int raid_disks = conf->previous_raid_disks;
4403        int data_disks = raid_disks - conf->max_degraded;
4404        int new_data_disks = conf->raid_disks - conf->max_degraded;
4405        int i;
4406        int dd_idx;
4407        sector_t writepos, readpos, safepos;
4408        sector_t stripe_addr;
4409        int reshape_sectors;
4410        struct list_head stripes;
4411
4412        if (sector_nr == 0) {
4413                /* If restarting in the middle, skip the initial sectors */
4414                if (mddev->reshape_backwards &&
4415                    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4416                        sector_nr = raid5_size(mddev, 0, 0)
4417                                - conf->reshape_progress;
4418                } else if (!mddev->reshape_backwards &&
4419                           conf->reshape_progress > 0)
4420                        sector_nr = conf->reshape_progress;
4421                sector_div(sector_nr, new_data_disks);
4422                if (sector_nr) {
4423                        mddev->curr_resync_completed = sector_nr;
4424                        sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4425                        *skipped = 1;
4426                        return sector_nr;
4427                }
4428        }
4429
4430        /* We need to process a full chunk at a time.
4431         * If old and new chunk sizes differ, we need to process the
4432         * largest of these
4433         */
4434        if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4435                reshape_sectors = mddev->new_chunk_sectors;
4436        else
4437                reshape_sectors = mddev->chunk_sectors;
4438
4439        /* We update the metadata at least every 10 seconds, or when
4440         * the data about to be copied would over-write the source of
4441         * the data at the front of the range.  i.e. one new_stripe
4442         * along from reshape_progress new_maps to after where
4443         * reshape_safe old_maps to
4444         */
4445        writepos = conf->reshape_progress;
4446        sector_div(writepos, new_data_disks);
4447        readpos = conf->reshape_progress;
4448        sector_div(readpos, data_disks);
4449        safepos = conf->reshape_safe;
4450        sector_div(safepos, data_disks);
4451        if (mddev->reshape_backwards) {
4452                writepos -= min_t(sector_t, reshape_sectors, writepos);
4453                readpos += reshape_sectors;
4454                safepos += reshape_sectors;
4455        } else {
4456                writepos += reshape_sectors;
4457                readpos -= min_t(sector_t, reshape_sectors, readpos);
4458                safepos -= min_t(sector_t, reshape_sectors, safepos);
4459        }
4460
4461        /* Having calculated the 'writepos' possibly use it
4462         * to set 'stripe_addr' which is where we will write to.
4463         */
4464        if (mddev->reshape_backwards) {
4465                BUG_ON(conf->reshape_progress == 0);
4466                stripe_addr = writepos;
4467                BUG_ON((mddev->dev_sectors &
4468                        ~((sector_t)reshape_sectors - 1))
4469                       - reshape_sectors - stripe_addr
4470                       != sector_nr);
4471        } else {
4472                BUG_ON(writepos != sector_nr + reshape_sectors);
4473                stripe_addr = sector_nr;
4474        }
4475
4476        /* 'writepos' is the most advanced device address we might write.
4477         * 'readpos' is the least advanced device address we might read.
4478         * 'safepos' is the least address recorded in the metadata as having
4479         *     been reshaped.
4480         * If there is a min_offset_diff, these are adjusted either by
4481         * increasing the safepos/readpos if diff is negative, or
4482         * increasing writepos if diff is positive.
4483         * If 'readpos' is then behind 'writepos', there is no way that we can
4484         * ensure safety in the face of a crash - that must be done by userspace
4485         * making a backup of the data.  So in that case there is no particular
4486         * rush to update metadata.
4487         * Otherwise if 'safepos' is behind 'writepos', then we really need to
4488         * update the metadata to advance 'safepos' to match 'readpos' so that
4489         * we can be safe in the event of a crash.
4490         * So we insist on updating metadata if safepos is behind writepos and
4491         * readpos is beyond writepos.
4492         * In any case, update the metadata every 10 seconds.
4493         * Maybe that number should be configurable, but I'm not sure it is
4494         * worth it.... maybe it could be a multiple of safemode_delay???
4495         */
4496        if (conf->min_offset_diff < 0) {
4497                safepos += -conf->min_offset_diff;
4498                readpos += -conf->min_offset_diff;
4499        } else
4500                writepos += conf->min_offset_diff;
4501
4502        if ((mddev->reshape_backwards
4503             ? (safepos > writepos && readpos < writepos)
4504             : (safepos < writepos && readpos > writepos)) ||
4505            time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4506                /* Cannot proceed until we've updated the superblock... */
4507                wait_event(conf->wait_for_overlap,
4508                           atomic_read(&conf->reshape_stripes)==0);
4509                mddev->reshape_position = conf->reshape_progress;
4510                mddev->curr_resync_completed = sector_nr;
4511                conf->reshape_checkpoint = jiffies;
4512                set_bit(MD_CHANGE_DEVS, &mddev->flags);
4513                md_wakeup_thread(mddev->thread);
4514                wait_event(mddev->sb_wait, mddev->flags == 0 ||
4515                           kthread_should_stop());
4516                spin_lock_irq(&conf->device_lock);
4517                conf->reshape_safe = mddev->reshape_position;
4518                spin_unlock_irq(&conf->device_lock);
4519                wake_up(&conf->wait_for_overlap);
4520                sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4521        }
4522
4523        INIT_LIST_HEAD(&stripes);
4524        for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4525                int j;
4526                int skipped_disk = 0;
4527                sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4528                set_bit(STRIPE_EXPANDING, &sh->state);
4529                atomic_inc(&conf->reshape_stripes);
4530                /* If any of this stripe is beyond the end of the old
4531                 * array, then we need to zero those blocks
4532                 */
4533                for (j=sh->disks; j--;) {
4534                        sector_t s;
4535                        if (j == sh->pd_idx)
4536                                continue;
4537                        if (conf->level == 6 &&
4538                            j == sh->qd_idx)
4539                                continue;
4540                        s = compute_blocknr(sh, j, 0);
4541                        if (s < raid5_size(mddev, 0, 0)) {
4542                                skipped_disk = 1;
4543                                continue;
4544                        }
4545                        memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4546                        set_bit(R5_Expanded, &sh->dev[j].flags);
4547                        set_bit(R5_UPTODATE, &sh->dev[j].flags);
4548                }
4549                if (!skipped_disk) {
4550                        set_bit(STRIPE_EXPAND_READY, &sh->state);
4551                        set_bit(STRIPE_HANDLE, &sh->state);
4552                }
4553                list_add(&sh->lru, &stripes);
4554        }
4555        spin_lock_irq(&conf->device_lock);
4556        if (mddev->reshape_backwards)
4557                conf->reshape_progress -= reshape_sectors * new_data_disks;
4558        else
4559                conf->reshape_progress += reshape_sectors * new_data_disks;
4560        spin_unlock_irq(&conf->device_lock);
4561        /* Ok, those stripe are ready. We can start scheduling
4562         * reads on the source stripes.
4563         * The source stripes are determined by mapping the first and last
4564         * block on the destination stripes.
4565         */
4566        first_sector =
4567                raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4568                                     1, &dd_idx, NULL);
4569        last_sector =
4570                raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4571                                            * new_data_disks - 1),
4572                                     1, &dd_idx, NULL);
4573        if (last_sector >= mddev->dev_sectors)
4574                last_sector = mddev->dev_sectors - 1;
4575        while (first_sector <= last_sector) {
4576                sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4577                set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4578                set_bit(STRIPE_HANDLE, &sh->state);
4579                release_stripe(sh);
4580                first_sector += STRIPE_SECTORS;
4581        }
4582        /* Now that the sources are clearly marked, we can release
4583         * the destination stripes
4584         */
4585        while (!list_empty(&stripes)) {
4586                sh = list_entry(stripes.next, struct stripe_head, lru);
4587                list_del_init(&sh->lru);
4588                release_stripe(sh);
4589        }
4590        /* If this takes us to the resync_max point where we have to pause,
4591         * then we need to write out the superblock.
4592         */
4593        sector_nr += reshape_sectors;
4594        if ((sector_nr - mddev->curr_resync_completed) * 2
4595            >= mddev->resync_max - mddev->curr_resync_completed) {
4596                /* Cannot proceed until we've updated the superblock... */
4597                wait_event(conf->wait_for_overlap,
4598                           atomic_read(&conf->reshape_stripes) == 0);
4599                mddev->reshape_position = conf->reshape_progress;
4600                mddev->curr_resync_completed = sector_nr;
4601                conf->reshape_checkpoint = jiffies;
4602                set_bit(MD_CHANGE_DEVS, &mddev->flags);
4603                md_wakeup_thread(mddev->thread);
4604                wait_event(mddev->sb_wait,
4605                           !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4606                           || kthread_should_stop());
4607                spin_lock_irq(&conf->device_lock);
4608                conf->reshape_safe = mddev->reshape_position;
4609                spin_unlock_irq(&conf->device_lock);
4610                wake_up(&conf->wait_for_overlap);
4611                sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4612        }
4613        return reshape_sectors;
4614}
4615
4616/* FIXME go_faster isn't used */
4617static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4618{
4619        struct r5conf *conf = mddev->private;
4620        struct stripe_head *sh;
4621        sector_t max_sector = mddev->dev_sectors;
4622        sector_t sync_blocks;
4623        int still_degraded = 0;
4624        int i;
4625
4626        if (sector_nr >= max_sector) {
4627                /* just being told to finish up .. nothing much to do */
4628
4629                if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4630                        end_reshape(conf);
4631                        return 0;
4632                }
4633
4634                if (mddev->curr_resync < max_sector) /* aborted */
4635                        bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4636                                        &sync_blocks, 1);
4637                else /* completed sync */
4638                        conf->fullsync = 0;
4639                bitmap_close_sync(mddev->bitmap);
4640
4641                return 0;
4642        }
4643
4644        /* Allow raid5_quiesce to complete */
4645        wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4646
4647        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4648                return reshape_request(mddev, sector_nr, skipped);
4649
4650        /* No need to check resync_max as we never do more than one
4651         * stripe, and as resync_max will always be on a chunk boundary,
4652         * if the check in md_do_sync didn't fire, there is no chance
4653         * of overstepping resync_max here
4654         */
4655
4656        /* if there is too many failed drives and we are trying
4657         * to resync, then assert that we are finished, because there is
4658         * nothing we can do.
4659         */
4660        if (mddev->degraded >= conf->max_degraded &&
4661            test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4662                sector_t rv = mddev->dev_sectors - sector_nr;
4663                *skipped = 1;
4664                return rv;
4665        }
4666        if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4667            !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4668            !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
4669                /* we can skip this block, and probably more */
4670                sync_blocks /= STRIPE_SECTORS;
4671                *skipped = 1;
4672                return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4673        }
4674
4675        bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4676
4677        sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4678        if (sh == NULL) {
4679                sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4680                /* make sure we don't swamp the stripe cache if someone else
4681                 * is trying to get access
4682                 */
4683                schedule_timeout_uninterruptible(1);
4684        }
4685        /* Need to check if array will still be degraded after recovery/resync
4686         * We don't need to check the 'failed' flag as when that gets set,
4687         * recovery aborts.
4688         */
4689        for (i = 0; i < conf->raid_disks; i++)
4690                if (conf->disks[i].rdev == NULL)
4691                        still_degraded = 1;
4692
4693        bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4694
4695        set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4696
4697        handle_stripe(sh);
4698        release_stripe(sh);
4699
4700        return STRIPE_SECTORS;
4701}
4702
4703static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
4704{
4705        /* We may not be able to submit a whole bio at once as there
4706         * may not be enough stripe_heads available.
4707         * We cannot pre-allocate enough stripe_heads as we may need
4708         * more than exist in the cache (if we allow ever large chunks).
4709         * So we do one stripe head at a time and record in
4710         * ->bi_hw_segments how many have been done.
4711         *
4712         * We *know* that this entire raid_bio is in one chunk, so
4713         * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4714         */
4715        struct stripe_head *sh;
4716        int dd_idx;
4717        sector_t sector, logical_sector, last_sector;
4718        int scnt = 0;
4719        int remaining;
4720        int handled = 0;
4721
4722        logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4723        sector = raid5_compute_sector(conf, logical_sector,
4724                                      0, &dd_idx, NULL);
4725        last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
4726
4727        for (; logical_sector < last_sector;
4728             logical_sector += STRIPE_SECTORS,
4729                     sector += STRIPE_SECTORS,
4730                     scnt++) {
4731
4732                if (scnt < raid5_bi_processed_stripes(raid_bio))
4733                        /* already done this stripe */
4734                        continue;
4735
4736                sh = get_active_stripe(conf, sector, 0, 1, 0);
4737
4738                if (!sh) {
4739                        /* failed to get a stripe - must wait */
4740                        raid5_set_bi_processed_stripes(raid_bio, scnt);
4741                        conf->retry_read_aligned = raid_bio;
4742                        return handled;
4743                }
4744
4745                if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4746                        release_stripe(sh);
4747                        raid5_set_bi_processed_stripes(raid_bio, scnt);
4748                        conf->retry_read_aligned = raid_bio;
4749                        return handled;
4750                }
4751
4752                set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
4753                handle_stripe(sh);
4754                release_stripe(sh);
4755                handled++;
4756        }
4757        remaining = raid5_dec_bi_active_stripes(raid_bio);
4758        if (remaining == 0) {
4759                trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
4760                                         raid_bio, 0);
4761                bio_endio(raid_bio, 0);
4762        }
4763        if (atomic_dec_and_test(&conf->active_aligned_reads))
4764                wake_up(&conf->wait_for_stripe);
4765        return handled;
4766}
4767
4768#define MAX_STRIPE_BATCH 8
4769static int handle_active_stripes(struct r5conf *conf)
4770{
4771        struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
4772        int i, batch_size = 0;
4773
4774        while (batch_size < MAX_STRIPE_BATCH &&
4775                        (sh = __get_priority_stripe(conf)) != NULL)
4776                batch[batch_size++] = sh;
4777
4778        if (batch_size == 0)
4779                return batch_size;
4780        spin_unlock_irq(&