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_sectors(bio);
  94        if (bio->bi_sector + sectors < sector + STRIPE_SECTORS)
  95                return bio->bi_next;
  96        else
  97                return NULL;
  98}
  99
 100/*
 101 * We maintain a biased count of active stripes in the bottom 16 bits of
 102 * bi_phys_segments, and a count of processed stripes in the upper 16 bits
 103 */
 104static inline int raid5_bi_processed_stripes(struct bio *bio)
 105{
 106        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 107        return (atomic_read(segments) >> 16) & 0xffff;
 108}
 109
 110static inline int raid5_dec_bi_active_stripes(struct bio *bio)
 111{
 112        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 113        return atomic_sub_return(1, segments) & 0xffff;
 114}
 115
 116static inline void raid5_inc_bi_active_stripes(struct bio *bio)
 117{
 118        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 119        atomic_inc(segments);
 120}
 121
 122static inline void raid5_set_bi_processed_stripes(struct bio *bio,
 123        unsigned int cnt)
 124{
 125        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 126        int old, new;
 127
 128        do {
 129                old = atomic_read(segments);
 130                new = (old & 0xffff) | (cnt << 16);
 131        } while (atomic_cmpxchg(segments, old, new) != old);
 132}
 133
 134static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
 135{
 136        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 137        atomic_set(segments, cnt);
 138}
 139
 140/* Find first data disk in a raid6 stripe */
 141static inline int raid6_d0(struct stripe_head *sh)
 142{
 143        if (sh->ddf_layout)
 144                /* ddf always start from first device */
 145                return 0;
 146        /* md starts just after Q block */
 147        if (sh->qd_idx == sh->disks - 1)
 148                return 0;
 149        else
 150                return sh->qd_idx + 1;
 151}
 152static inline int raid6_next_disk(int disk, int raid_disks)
 153{
 154        disk++;
 155        return (disk < raid_disks) ? disk : 0;
 156}
 157
 158/* When walking through the disks in a raid5, starting at raid6_d0,
 159 * We need to map each disk to a 'slot', where the data disks are slot
 160 * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 161 * is raid_disks-1.  This help does that mapping.
 162 */
 163static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 164                             int *count, int syndrome_disks)
 165{
 166        int slot = *count;
 167
 168        if (sh->ddf_layout)
 169                (*count)++;
 170        if (idx == sh->pd_idx)
 171                return syndrome_disks;
 172        if (idx == sh->qd_idx)
 173                return syndrome_disks + 1;
 174        if (!sh->ddf_layout)
 175                (*count)++;
 176        return slot;
 177}
 178
 179static void return_io(struct bio *return_bi)
 180{
 181        struct bio *bi = return_bi;
 182        while (bi) {
 183
 184                return_bi = bi->bi_next;
 185                bi->bi_next = NULL;
 186                bi->bi_size = 0;
 187                trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 188                                         bi, 0);
 189                bio_endio(bi, 0);
 190                bi = return_bi;
 191        }
 192}
 193
 194static void print_raid5_conf (struct r5conf *conf);
 195
 196static int stripe_operations_active(struct stripe_head *sh)
 197{
 198        return sh->check_state || sh->reconstruct_state ||
 199               test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 200               test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 201}
 202
 203static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh)
 204{
 205        BUG_ON(!list_empty(&sh->lru));
 206        BUG_ON(atomic_read(&conf->active_stripes)==0);
 207        if (test_bit(STRIPE_HANDLE, &sh->state)) {
 208                if (test_bit(STRIPE_DELAYED, &sh->state) &&
 209                    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 210                        list_add_tail(&sh->lru, &conf->delayed_list);
 211                else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 212                           sh->bm_seq - conf->seq_write > 0)
 213                        list_add_tail(&sh->lru, &conf->bitmap_list);
 214                else {
 215                        clear_bit(STRIPE_DELAYED, &sh->state);
 216                        clear_bit(STRIPE_BIT_DELAY, &sh->state);
 217                        list_add_tail(&sh->lru, &conf->handle_list);
 218                }
 219                md_wakeup_thread(conf->mddev->thread);
 220        } else {
 221                BUG_ON(stripe_operations_active(sh));
 222                if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 223                        if (atomic_dec_return(&conf->preread_active_stripes)
 224                            < IO_THRESHOLD)
 225                                md_wakeup_thread(conf->mddev->thread);
 226                atomic_dec(&conf->active_stripes);
 227                if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 228                        list_add_tail(&sh->lru, &conf->inactive_list);
 229                        wake_up(&conf->wait_for_stripe);
 230                        if (conf->retry_read_aligned)
 231                                md_wakeup_thread(conf->mddev->thread);
 232                }
 233        }
 234}
 235
 236static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
 237{
 238        if (atomic_dec_and_test(&sh->count))
 239                do_release_stripe(conf, sh);
 240}
 241
 242static void release_stripe(struct stripe_head *sh)
 243{
 244        struct r5conf *conf = sh->raid_conf;
 245        unsigned long flags;
 246
 247        local_irq_save(flags);
 248        if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 249                do_release_stripe(conf, sh);
 250                spin_unlock(&conf->device_lock);
 251        }
 252        local_irq_restore(flags);
 253}
 254
 255static inline void remove_hash(struct stripe_head *sh)
 256{
 257        pr_debug("remove_hash(), stripe %llu\n",
 258                (unsigned long long)sh->sector);
 259
 260        hlist_del_init(&sh->hash);
 261}
 262
 263static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 264{
 265        struct hlist_head *hp = stripe_hash(conf, sh->sector);
 266
 267        pr_debug("insert_hash(), stripe %llu\n",
 268                (unsigned long long)sh->sector);
 269
 270        hlist_add_head(&sh->hash, hp);
 271}
 272
 273
 274/* find an idle stripe, make sure it is unhashed, and return it. */
 275static struct stripe_head *get_free_stripe(struct r5conf *conf)
 276{
 277        struct stripe_head *sh = NULL;
 278        struct list_head *first;
 279
 280        if (list_empty(&conf->inactive_list))
 281                goto out;
 282        first = conf->inactive_list.next;
 283        sh = list_entry(first, struct stripe_head, lru);
 284        list_del_init(first);
 285        remove_hash(sh);
 286        atomic_inc(&conf->active_stripes);
 287out:
 288        return sh;
 289}
 290
 291static void shrink_buffers(struct stripe_head *sh)
 292{
 293        struct page *p;
 294        int i;
 295        int num = sh->raid_conf->pool_size;
 296
 297        for (i = 0; i < num ; i++) {
 298                p = sh->dev[i].page;
 299                if (!p)
 300                        continue;
 301                sh->dev[i].page = NULL;
 302                put_page(p);
 303        }
 304}
 305
 306static int grow_buffers(struct stripe_head *sh)
 307{
 308        int i;
 309        int num = sh->raid_conf->pool_size;
 310
 311        for (i = 0; i < num; i++) {
 312                struct page *page;
 313
 314                if (!(page = alloc_page(GFP_KERNEL))) {
 315                        return 1;
 316                }
 317                sh->dev[i].page = page;
 318        }
 319        return 0;
 320}
 321
 322static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 323static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 324                            struct stripe_head *sh);
 325
 326static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 327{
 328        struct r5conf *conf = sh->raid_conf;
 329        int i;
 330
 331        BUG_ON(atomic_read(&sh->count) != 0);
 332        BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 333        BUG_ON(stripe_operations_active(sh));
 334
 335        pr_debug("init_stripe called, stripe %llu\n",
 336                (unsigned long long)sh->sector);
 337
 338        remove_hash(sh);
 339
 340        sh->generation = conf->generation - previous;
 341        sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 342        sh->sector = sector;
 343        stripe_set_idx(sector, conf, previous, sh);
 344        sh->state = 0;
 345
 346
 347        for (i = sh->disks; i--; ) {
 348                struct r5dev *dev = &sh->dev[i];
 349
 350                if (dev->toread || dev->read || dev->towrite || dev->written ||
 351                    test_bit(R5_LOCKED, &dev->flags)) {
 352                        printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 353                               (unsigned long long)sh->sector, i, dev->toread,
 354                               dev->read, dev->towrite, dev->written,
 355                               test_bit(R5_LOCKED, &dev->flags));
 356                        WARN_ON(1);
 357                }
 358                dev->flags = 0;
 359                raid5_build_block(sh, i, previous);
 360        }
 361        insert_hash(conf, sh);
 362}
 363
 364static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 365                                         short generation)
 366{
 367        struct stripe_head *sh;
 368
 369        pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 370        hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 371                if (sh->sector == sector && sh->generation == generation)
 372                        return sh;
 373        pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 374        return NULL;
 375}
 376
 377/*
 378 * Need to check if array has failed when deciding whether to:
 379 *  - start an array
 380 *  - remove non-faulty devices
 381 *  - add a spare
 382 *  - allow a reshape
 383 * This determination is simple when no reshape is happening.
 384 * However if there is a reshape, we need to carefully check
 385 * both the before and after sections.
 386 * This is because some failed devices may only affect one
 387 * of the two sections, and some non-in_sync devices may
 388 * be insync in the section most affected by failed devices.
 389 */
 390static int calc_degraded(struct r5conf *conf)
 391{
 392        int degraded, degraded2;
 393        int i;
 394
 395        rcu_read_lock();
 396        degraded = 0;
 397        for (i = 0; i < conf->previous_raid_disks; i++) {
 398                struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 399                if (rdev && test_bit(Faulty, &rdev->flags))
 400                        rdev = rcu_dereference(conf->disks[i].replacement);
 401                if (!rdev || test_bit(Faulty, &rdev->flags))
 402                        degraded++;
 403                else if (test_bit(In_sync, &rdev->flags))
 404                        ;
 405                else
 406                        /* not in-sync or faulty.
 407                         * If the reshape increases the number of devices,
 408                         * this is being recovered by the reshape, so
 409                         * this 'previous' section is not in_sync.
 410                         * If the number of devices is being reduced however,
 411                         * the device can only be part of the array if
 412                         * we are reverting a reshape, so this section will
 413                         * be in-sync.
 414                         */
 415                        if (conf->raid_disks >= conf->previous_raid_disks)
 416                                degraded++;
 417        }
 418        rcu_read_unlock();
 419        if (conf->raid_disks == conf->previous_raid_disks)
 420                return degraded;
 421        rcu_read_lock();
 422        degraded2 = 0;
 423        for (i = 0; i < conf->raid_disks; i++) {
 424                struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 425                if (rdev && test_bit(Faulty, &rdev->flags))
 426                        rdev = rcu_dereference(conf->disks[i].replacement);
 427                if (!rdev || test_bit(Faulty, &rdev->flags))
 428                        degraded2++;
 429                else if (test_bit(In_sync, &rdev->flags))
 430                        ;
 431                else
 432                        /* not in-sync or faulty.
 433                         * If reshape increases the number of devices, this
 434                         * section has already been recovered, else it
 435                         * almost certainly hasn't.
 436                         */
 437                        if (conf->raid_disks <= conf->previous_raid_disks)
 438                                degraded2++;
 439        }
 440        rcu_read_unlock();
 441        if (degraded2 > degraded)
 442                return degraded2;
 443        return degraded;
 444}
 445
 446static int has_failed(struct r5conf *conf)
 447{
 448        int degraded;
 449
 450        if (conf->mddev->reshape_position == MaxSector)
 451                return conf->mddev->degraded > conf->max_degraded;
 452
 453        degraded = calc_degraded(conf);
 454        if (degraded > conf->max_degraded)
 455                return 1;
 456        return 0;
 457}
 458
 459static struct stripe_head *
 460get_active_stripe(struct r5conf *conf, sector_t sector,
 461                  int previous, int noblock, int noquiesce)
 462{
 463        struct stripe_head *sh;
 464
 465        pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 466
 467        spin_lock_irq(&conf->device_lock);
 468
 469        do {
 470                wait_event_lock_irq(conf->wait_for_stripe,
 471                                    conf->quiesce == 0 || noquiesce,
 472                                    conf->device_lock);
 473                sh = __find_stripe(conf, sector, conf->generation - previous);
 474                if (!sh) {
 475                        if (!conf->inactive_blocked)
 476                                sh = get_free_stripe(conf);
 477                        if (noblock && sh == NULL)
 478                                break;
 479                        if (!sh) {
 480                                conf->inactive_blocked = 1;
 481                                wait_event_lock_irq(conf->wait_for_stripe,
 482                                                    !list_empty(&conf->inactive_list) &&
 483                                                    (atomic_read(&conf->active_stripes)
 484                                                     < (conf->max_nr_stripes *3/4)
 485                                                     || !conf->inactive_blocked),
 486                                                    conf->device_lock);
 487                                conf->inactive_blocked = 0;
 488                        } else
 489                                init_stripe(sh, sector, previous);
 490                } else {
 491                        if (atomic_read(&sh->count)) {
 492                                BUG_ON(!list_empty(&sh->lru)
 493                                    && !test_bit(STRIPE_EXPANDING, &sh->state)
 494                                    && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
 495                        } else {
 496                                if (!test_bit(STRIPE_HANDLE, &sh->state))
 497                                        atomic_inc(&conf->active_stripes);
 498                                if (list_empty(&sh->lru) &&
 499                                    !test_bit(STRIPE_EXPANDING, &sh->state))
 500                                        BUG();
 501                                list_del_init(&sh->lru);
 502                        }
 503                }
 504        } while (sh == NULL);
 505
 506        if (sh)
 507                atomic_inc(&sh->count);
 508
 509        spin_unlock_irq(&conf->device_lock);
 510        return sh;
 511}
 512
 513/* Determine if 'data_offset' or 'new_data_offset' should be used
 514 * in this stripe_head.
 515 */
 516static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 517{
 518        sector_t progress = conf->reshape_progress;
 519        /* Need a memory barrier to make sure we see the value
 520         * of conf->generation, or ->data_offset that was set before
 521         * reshape_progress was updated.
 522         */
 523        smp_rmb();
 524        if (progress == MaxSector)
 525                return 0;
 526        if (sh->generation == conf->generation - 1)
 527                return 0;
 528        /* We are in a reshape, and this is a new-generation stripe,
 529         * so use new_data_offset.
 530         */
 531        return 1;
 532}
 533
 534static void
 535raid5_end_read_request(struct bio *bi, int error);
 536static void
 537raid5_end_write_request(struct bio *bi, int error);
 538
 539static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 540{
 541        struct r5conf *conf = sh->raid_conf;
 542        int i, disks = sh->disks;
 543
 544        might_sleep();
 545
 546        for (i = disks; i--; ) {
 547                int rw;
 548                int replace_only = 0;
 549                struct bio *bi, *rbi;
 550                struct md_rdev *rdev, *rrdev = NULL;
 551                if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 552                        if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 553                                rw = WRITE_FUA;
 554                        else
 555                                rw = WRITE;
 556                        if (test_bit(R5_Discard, &sh->dev[i].flags))
 557                                rw |= REQ_DISCARD;
 558                } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 559                        rw = READ;
 560                else if (test_and_clear_bit(R5_WantReplace,
 561                                            &sh->dev[i].flags)) {
 562                        rw = WRITE;
 563                        replace_only = 1;
 564                } else
 565                        continue;
 566                if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 567                        rw |= REQ_SYNC;
 568
 569                bi = &sh->dev[i].req;
 570                rbi = &sh->dev[i].rreq; /* For writing to replacement */
 571
 572                rcu_read_lock();
 573                rrdev = rcu_dereference(conf->disks[i].replacement);
 574                smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 575                rdev = rcu_dereference(conf->disks[i].rdev);
 576                if (!rdev) {
 577                        rdev = rrdev;
 578                        rrdev = NULL;
 579                }
 580                if (rw & WRITE) {
 581                        if (replace_only)
 582                                rdev = NULL;
 583                        if (rdev == rrdev)
 584                                /* We raced and saw duplicates */
 585                                rrdev = NULL;
 586                } else {
 587                        if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
 588                                rdev = rrdev;
 589                        rrdev = NULL;
 590                }
 591
 592                if (rdev && test_bit(Faulty, &rdev->flags))
 593                        rdev = NULL;
 594                if (rdev)
 595                        atomic_inc(&rdev->nr_pending);
 596                if (rrdev && test_bit(Faulty, &rrdev->flags))
 597                        rrdev = NULL;
 598                if (rrdev)
 599                        atomic_inc(&rrdev->nr_pending);
 600                rcu_read_unlock();
 601
 602                /* We have already checked bad blocks for reads.  Now
 603                 * need to check for writes.  We never accept write errors
 604                 * on the replacement, so we don't to check rrdev.
 605                 */
 606                while ((rw & WRITE) && rdev &&
 607                       test_bit(WriteErrorSeen, &rdev->flags)) {
 608                        sector_t first_bad;
 609                        int bad_sectors;
 610                        int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 611                                              &first_bad, &bad_sectors);
 612                        if (!bad)
 613                                break;
 614
 615                        if (bad < 0) {
 616                                set_bit(BlockedBadBlocks, &rdev->flags);
 617                                if (!conf->mddev->external &&
 618                                    conf->mddev->flags) {
 619                                        /* It is very unlikely, but we might
 620                                         * still need to write out the
 621                                         * bad block log - better give it
 622                                         * a chance*/
 623                                        md_check_recovery(conf->mddev);
 624                                }
 625                                /*
 626                                 * Because md_wait_for_blocked_rdev
 627                                 * will dec nr_pending, we must
 628                                 * increment it first.
 629                                 */
 630                                atomic_inc(&rdev->nr_pending);
 631                                md_wait_for_blocked_rdev(rdev, conf->mddev);
 632                        } else {
 633                                /* Acknowledged bad block - skip the write */
 634                                rdev_dec_pending(rdev, conf->mddev);
 635                                rdev = NULL;
 636                        }
 637                }
 638
 639                if (rdev) {
 640                        if (s->syncing || s->expanding || s->expanded
 641                            || s->replacing)
 642                                md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 643
 644                        set_bit(STRIPE_IO_STARTED, &sh->state);
 645
 646                        bio_reset(bi);
 647                        bi->bi_bdev = rdev->bdev;
 648                        bi->bi_rw = rw;
 649                        bi->bi_end_io = (rw & WRITE)
 650                                ? raid5_end_write_request
 651                                : raid5_end_read_request;
 652                        bi->bi_private = sh;
 653
 654                        pr_debug("%s: for %llu schedule op %ld on disc %d\n",
 655                                __func__, (unsigned long long)sh->sector,
 656                                bi->bi_rw, i);
 657                        atomic_inc(&sh->count);
 658                        if (use_new_offset(conf, sh))
 659                                bi->bi_sector = (sh->sector
 660                                                 + rdev->new_data_offset);
 661                        else
 662                                bi->bi_sector = (sh->sector
 663                                                 + rdev->data_offset);
 664                        if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
 665                                bi->bi_rw |= REQ_FLUSH;
 666
 667                        bi->bi_vcnt = 1;
 668                        bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 669                        bi->bi_io_vec[0].bv_offset = 0;
 670                        bi->bi_size = STRIPE_SIZE;
 671                        if (rrdev)
 672                                set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
 673
 674                        if (conf->mddev->gendisk)
 675                                trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
 676                                                      bi, disk_devt(conf->mddev->gendisk),
 677                                                      sh->dev[i].sector);
 678                        generic_make_request(bi);
 679                }
 680                if (rrdev) {
 681                        if (s->syncing || s->expanding || s->expanded
 682                            || s->replacing)
 683                                md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
 684
 685                        set_bit(STRIPE_IO_STARTED, &sh->state);
 686
 687                        bio_reset(rbi);
 688                        rbi->bi_bdev = rrdev->bdev;
 689                        rbi->bi_rw = rw;
 690                        BUG_ON(!(rw & WRITE));
 691                        rbi->bi_end_io = raid5_end_write_request;
 692                        rbi->bi_private = sh;
 693
 694                        pr_debug("%s: for %llu schedule op %ld on "
 695                                 "replacement disc %d\n",
 696                                __func__, (unsigned long long)sh->sector,
 697                                rbi->bi_rw, i);
 698                        atomic_inc(&sh->count);
 699                        if (use_new_offset(conf, sh))
 700                                rbi->bi_sector = (sh->sector
 701                                                  + rrdev->new_data_offset);
 702                        else
 703                                rbi->bi_sector = (sh->sector
 704                                                  + rrdev->data_offset);
 705                        rbi->bi_vcnt = 1;
 706                        rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 707                        rbi->bi_io_vec[0].bv_offset = 0;
 708                        rbi->bi_size = STRIPE_SIZE;
 709                        if (conf->mddev->gendisk)
 710                                trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
 711                                                      rbi, disk_devt(conf->mddev->gendisk),
 712                                                      sh->dev[i].sector);
 713                        generic_make_request(rbi);
 714                }
 715                if (!rdev && !rrdev) {
 716                        if (rw & WRITE)
 717                                set_bit(STRIPE_DEGRADED, &sh->state);
 718                        pr_debug("skip op %ld on disc %d for sector %llu\n",
 719                                bi->bi_rw, i, (unsigned long long)sh->sector);
 720                        clear_bit(R5_LOCKED, &sh->dev[i].flags);
 721                        set_bit(STRIPE_HANDLE, &sh->state);
 722                }
 723        }
 724}
 725
 726static struct dma_async_tx_descriptor *
 727async_copy_data(int frombio, struct bio *bio, struct page *page,
 728        sector_t sector, struct dma_async_tx_descriptor *tx)
 729{
 730        struct bio_vec *bvl;
 731        struct page *bio_page;
 732        int i;
 733        int page_offset;
 734        struct async_submit_ctl submit;
 735        enum async_tx_flags flags = 0;
 736
 737        if (bio->bi_sector >= sector)
 738                page_offset = (signed)(bio->bi_sector - sector) * 512;
 739        else
 740                page_offset = (signed)(sector - bio->bi_sector) * -512;
 741
 742        if (frombio)
 743                flags |= ASYNC_TX_FENCE;
 744        init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
 745
 746        bio_for_each_segment(bvl, bio, i) {
 747                int len = bvl->bv_len;
 748                int clen;
 749                int b_offset = 0;
 750
 751                if (page_offset < 0) {
 752                        b_offset = -page_offset;
 753                        page_offset += b_offset;
 754                        len -= b_offset;
 755                }
 756
 757                if (len > 0 && page_offset + len > STRIPE_SIZE)
 758                        clen = STRIPE_SIZE - page_offset;
 759                else
 760                        clen = len;
 761
 762                if (clen > 0) {
 763                        b_offset += bvl->bv_offset;
 764                        bio_page = bvl->bv_page;
 765                        if (frombio)
 766                                tx = async_memcpy(page, bio_page, page_offset,
 767                                                  b_offset, clen, &submit);
 768                        else
 769                                tx = async_memcpy(bio_page, page, b_offset,
 770                                                  page_offset, clen, &submit);
 771                }
 772                /* chain the operations */
 773                submit.depend_tx = tx;
 774
 775                if (clen < len) /* hit end of page */
 776                        break;
 777                page_offset +=  len;
 778        }
 779
 780        return tx;
 781}
 782
 783static void ops_complete_biofill(void *stripe_head_ref)
 784{
 785        struct stripe_head *sh = stripe_head_ref;
 786        struct bio *return_bi = NULL;
 787        int i;
 788
 789        pr_debug("%s: stripe %llu\n", __func__,
 790                (unsigned long long)sh->sector);
 791
 792        /* clear completed biofills */
 793        for (i = sh->disks; i--; ) {
 794                struct r5dev *dev = &sh->dev[i];
 795
 796                /* acknowledge completion of a biofill operation */
 797                /* and check if we need to reply to a read request,
 798                 * new R5_Wantfill requests are held off until
 799                 * !STRIPE_BIOFILL_RUN
 800                 */
 801                if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
 802                        struct bio *rbi, *rbi2;
 803
 804                        BUG_ON(!dev->read);
 805                        rbi = dev->read;
 806                        dev->read = NULL;
 807                        while (rbi && rbi->bi_sector <
 808                                dev->sector + STRIPE_SECTORS) {
 809                                rbi2 = r5_next_bio(rbi, dev->sector);
 810                                if (!raid5_dec_bi_active_stripes(rbi)) {
 811                                        rbi->bi_next = return_bi;
 812                                        return_bi = rbi;
 813                                }
 814                                rbi = rbi2;
 815                        }
 816                }
 817        }
 818        clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
 819
 820        return_io(return_bi);
 821
 822        set_bit(STRIPE_HANDLE, &sh->state);
 823        release_stripe(sh);
 824}
 825
 826static void ops_run_biofill(struct stripe_head *sh)
 827{
 828        struct dma_async_tx_descriptor *tx = NULL;
 829        struct async_submit_ctl submit;
 830        int i;
 831
 832        pr_debug("%s: stripe %llu\n", __func__,
 833                (unsigned long long)sh->sector);
 834
 835        for (i = sh->disks; i--; ) {
 836                struct r5dev *dev = &sh->dev[i];
 837                if (test_bit(R5_Wantfill, &dev->flags)) {
 838                        struct bio *rbi;
 839                        spin_lock_irq(&sh->stripe_lock);
 840                        dev->read = rbi = dev->toread;
 841                        dev->toread = NULL;
 842                        spin_unlock_irq(&sh->stripe_lock);
 843                        while (rbi && rbi->bi_sector <
 844                                dev->sector + STRIPE_SECTORS) {
 845                                tx = async_copy_data(0, rbi, dev->page,
 846                                        dev->sector, tx);
 847                                rbi = r5_next_bio(rbi, dev->sector);
 848                        }
 849                }
 850        }
 851
 852        atomic_inc(&sh->count);
 853        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
 854        async_trigger_callback(&submit);
 855}
 856
 857static void mark_target_uptodate(struct stripe_head *sh, int target)
 858{
 859        struct r5dev *tgt;
 860
 861        if (target < 0)
 862                return;
 863
 864        tgt = &sh->dev[target];
 865        set_bit(R5_UPTODATE, &tgt->flags);
 866        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 867        clear_bit(R5_Wantcompute, &tgt->flags);
 868}
 869
 870static void ops_complete_compute(void *stripe_head_ref)
 871{
 872        struct stripe_head *sh = stripe_head_ref;
 873
 874        pr_debug("%s: stripe %llu\n", __func__,
 875                (unsigned long long)sh->sector);
 876
 877        /* mark the computed target(s) as uptodate */
 878        mark_target_uptodate(sh, sh->ops.target);
 879        mark_target_uptodate(sh, sh->ops.target2);
 880
 881        clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
 882        if (sh->check_state == check_state_compute_run)
 883                sh->check_state = check_state_compute_result;
 884        set_bit(STRIPE_HANDLE, &sh->state);
 885        release_stripe(sh);
 886}
 887
 888/* return a pointer to the address conversion region of the scribble buffer */
 889static addr_conv_t *to_addr_conv(struct stripe_head *sh,
 890                                 struct raid5_percpu *percpu)
 891{
 892        return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
 893}
 894
 895static struct dma_async_tx_descriptor *
 896ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
 897{
 898        int disks = sh->disks;
 899        struct page **xor_srcs = percpu->scribble;
 900        int target = sh->ops.target;
 901        struct r5dev *tgt = &sh->dev[target];
 902        struct page *xor_dest = tgt->page;
 903        int count = 0;
 904        struct dma_async_tx_descriptor *tx;
 905        struct async_submit_ctl submit;
 906        int i;
 907
 908        pr_debug("%s: stripe %llu block: %d\n",
 909                __func__, (unsigned long long)sh->sector, target);
 910        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 911
 912        for (i = disks; i--; )
 913                if (i != target)
 914                        xor_srcs[count++] = sh->dev[i].page;
 915
 916        atomic_inc(&sh->count);
 917
 918        init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
 919                          ops_complete_compute, sh, to_addr_conv(sh, percpu));
 920        if (unlikely(count == 1))
 921                tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
 922        else
 923                tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
 924
 925        return tx;
 926}
 927
 928/* set_syndrome_sources - populate source buffers for gen_syndrome
 929 * @srcs - (struct page *) array of size sh->disks
 930 * @sh - stripe_head to parse
 931 *
 932 * Populates srcs in proper layout order for the stripe and returns the
 933 * 'count' of sources to be used in a call to async_gen_syndrome.  The P
 934 * destination buffer is recorded in srcs[count] and the Q destination
 935 * is recorded in srcs[count+1]].
 936 */
 937static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
 938{
 939        int disks = sh->disks;
 940        int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
 941        int d0_idx = raid6_d0(sh);
 942        int count;
 943        int i;
 944
 945        for (i = 0; i < disks; i++)
 946                srcs[i] = NULL;
 947
 948        count = 0;
 949        i = d0_idx;
 950        do {
 951                int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
 952
 953                srcs[slot] = sh->dev[i].page;
 954                i = raid6_next_disk(i, disks);
 955        } while (i != d0_idx);
 956
 957        return syndrome_disks;
 958}
 959
 960static struct dma_async_tx_descriptor *
 961ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
 962{
 963        int disks = sh->disks;
 964        struct page **blocks = percpu->scribble;
 965        int target;
 966        int qd_idx = sh->qd_idx;
 967        struct dma_async_tx_descriptor *tx;
 968        struct async_submit_ctl submit;
 969        struct r5dev *tgt;
 970        struct page *dest;
 971        int i;
 972        int count;
 973
 974        if (sh->ops.target < 0)
 975                target = sh->ops.target2;
 976        else if (sh->ops.target2 < 0)
 977                target = sh->ops.target;
 978        else
 979                /* we should only have one valid target */
 980                BUG();
 981        BUG_ON(target < 0);
 982        pr_debug("%s: stripe %llu block: %d\n",
 983                __func__, (unsigned long long)sh->sector, target);
 984
 985        tgt = &sh->dev[target];
 986        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 987        dest = tgt->page;
 988
 989        atomic_inc(&sh->count);
 990
 991        if (target == qd_idx) {
 992                count = set_syndrome_sources(blocks, sh);
 993                blocks[count] = NULL; /* regenerating p is not necessary */
 994                BUG_ON(blocks[count+1] != dest); /* q should already be set */
 995                init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
 996                                  ops_complete_compute, sh,
 997                                  to_addr_conv(sh, percpu));
 998                tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
 999        } else {
1000                /* Compute any data- or p-drive using XOR */
1001                count = 0;
1002                for (i = disks; i-- ; ) {
1003                        if (i == target || i == qd_idx)
1004                                continue;
1005                        blocks[count++] = sh->dev[i].page;
1006                }
1007
1008                init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1009                                  NULL, ops_complete_compute, sh,
1010                                  to_addr_conv(sh, percpu));
1011                tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1012        }
1013
1014        return tx;
1015}
1016
1017static struct dma_async_tx_descriptor *
1018ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1019{
1020        int i, count, disks = sh->disks;
1021        int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1022        int d0_idx = raid6_d0(sh);
1023        int faila = -1, failb = -1;
1024        int target = sh->ops.target;
1025        int target2 = sh->ops.target2;
1026        struct r5dev *tgt = &sh->dev[target];
1027        struct r5dev *tgt2 = &sh->dev[target2];
1028        struct dma_async_tx_descriptor *tx;
1029        struct page **blocks = percpu->scribble;
1030        struct async_submit_ctl submit;
1031
1032        pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1033                 __func__, (unsigned long long)sh->sector, target, target2);
1034        BUG_ON(target < 0 || target2 < 0);
1035        BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1036        BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1037
1038        /* we need to open-code set_syndrome_sources to handle the
1039         * slot number conversion for 'faila' and 'failb'
1040         */
1041        for (i = 0; i < disks ; i++)
1042                blocks[i] = NULL;
1043        count = 0;
1044        i = d0_idx;
1045        do {
1046                int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1047
1048                blocks[slot] = sh->dev[i].page;
1049
1050                if (i == target)
1051                        faila = slot;
1052                if (i == target2)
1053                        failb = slot;
1054                i = raid6_next_disk(i, disks);
1055        } while (i != d0_idx);
1056
1057        BUG_ON(faila == failb);
1058        if (failb < faila)
1059                swap(faila, failb);
1060        pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1061                 __func__, (unsigned long long)sh->sector, faila, failb);
1062
1063        atomic_inc(&sh->count);
1064
1065        if (failb == syndrome_disks+1) {
1066                /* Q disk is one of the missing disks */
1067                if (faila == syndrome_disks) {
1068                        /* Missing P+Q, just recompute */
1069                        init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1070                                          ops_complete_compute, sh,
1071                                          to_addr_conv(sh, percpu));
1072                        return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1073                                                  STRIPE_SIZE, &submit);
1074                } else {
1075                        struct page *dest;
1076                        int data_target;
1077                        int qd_idx = sh->qd_idx;
1078
1079                        /* Missing D+Q: recompute D from P, then recompute Q */
1080                        if (target == qd_idx)
1081                                data_target = target2;
1082                        else
1083                                data_target = target;
1084
1085                        count = 0;
1086                        for (i = disks; i-- ; ) {
1087                                if (i == data_target || i == qd_idx)
1088                                        continue;
1089                                blocks[count++] = sh->dev[i].page;
1090                        }
1091                        dest = sh->dev[data_target].page;
1092                        init_async_submit(&submit,
1093                                          ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1094                                          NULL, NULL, NULL,
1095                                          to_addr_conv(sh, percpu));
1096                        tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1097                                       &submit);
1098
1099                        count = set_syndrome_sources(blocks, sh);
1100                        init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1101                                          ops_complete_compute, sh,
1102                                          to_addr_conv(sh, percpu));
1103                        return async_gen_syndrome(blocks, 0, count+2,
1104                                                  STRIPE_SIZE, &submit);
1105                }
1106        } else {
1107                init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1108                                  ops_complete_compute, sh,
1109                                  to_addr_conv(sh, percpu));
1110                if (failb == syndrome_disks) {
1111                        /* We're missing D+P. */
1112                        return async_raid6_datap_recov(syndrome_disks+2,
1113                                                       STRIPE_SIZE, faila,
1114                                                       blocks, &submit);
1115                } else {
1116                        /* We're missing D+D. */
1117                        return async_raid6_2data_recov(syndrome_disks+2,
1118                                                       STRIPE_SIZE, faila, failb,
1119                                                       blocks, &submit);
1120                }
1121        }
1122}
1123
1124
1125static void ops_complete_prexor(void *stripe_head_ref)
1126{
1127        struct stripe_head *sh = stripe_head_ref;
1128
1129        pr_debug("%s: stripe %llu\n", __func__,
1130                (unsigned long long)sh->sector);
1131}
1132
1133static struct dma_async_tx_descriptor *
1134ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1135               struct dma_async_tx_descriptor *tx)
1136{
1137        int disks = sh->disks;
1138        struct page **xor_srcs = percpu->scribble;
1139        int count = 0, pd_idx = sh->pd_idx, i;
1140        struct async_submit_ctl submit;
1141
1142        /* existing parity data subtracted */
1143        struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1144
1145        pr_debug("%s: stripe %llu\n", __func__,
1146                (unsigned long long)sh->sector);
1147
1148        for (i = disks; i--; ) {
1149                struct r5dev *dev = &sh->dev[i];
1150                /* Only process blocks that are known to be uptodate */
1151                if (test_bit(R5_Wantdrain, &dev->flags))
1152                        xor_srcs[count++] = dev->page;
1153        }
1154
1155        init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1156                          ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1157        tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1158
1159        return tx;
1160}
1161
1162static struct dma_async_tx_descriptor *
1163ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1164{
1165        int disks = sh->disks;
1166        int i;
1167
1168        pr_debug("%s: stripe %llu\n", __func__,
1169                (unsigned long long)sh->sector);
1170
1171        for (i = disks; i--; ) {
1172                struct r5dev *dev = &sh->dev[i];
1173                struct bio *chosen;
1174
1175                if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1176                        struct bio *wbi;
1177
1178                        spin_lock_irq(&sh->stripe_lock);
1179                        chosen = dev->towrite;
1180                        dev->towrite = NULL;
1181                        BUG_ON(dev->written);
1182                        wbi = dev->written = chosen;
1183                        spin_unlock_irq(&sh->stripe_lock);
1184
1185                        while (wbi && wbi->bi_sector <
1186                                dev->sector + STRIPE_SECTORS) {
1187                                if (wbi->bi_rw & REQ_FUA)
1188                                        set_bit(R5_WantFUA, &dev->flags);
1189                                if (wbi->bi_rw & REQ_SYNC)
1190                                        set_bit(R5_SyncIO, &dev->flags);
1191                                if (wbi->bi_rw & REQ_DISCARD)
1192                                        set_bit(R5_Discard, &dev->flags);
1193                                else
1194                                        tx = async_copy_data(1, wbi, dev->page,
1195                                                dev->sector, tx);
1196                                wbi = r5_next_bio(wbi, dev->sector);
1197                        }
1198                }
1199        }
1200
1201        return tx;
1202}
1203
1204static void ops_complete_reconstruct(void *stripe_head_ref)
1205{
1206        struct stripe_head *sh = stripe_head_ref;
1207        int disks = sh->disks;
1208        int pd_idx = sh->pd_idx;
1209        int qd_idx = sh->qd_idx;
1210        int i;
1211        bool fua = false, sync = false, discard = false;
1212
1213        pr_debug("%s: stripe %llu\n", __func__,
1214                (unsigned long long)sh->sector);
1215
1216        for (i = disks; i--; ) {
1217                fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1218                sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1219                discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1220        }
1221
1222        for (i = disks; i--; ) {
1223                struct r5dev *dev = &sh->dev[i];
1224
1225                if (dev->written || i == pd_idx || i == qd_idx) {
1226                        if (!discard)
1227                                set_bit(R5_UPTODATE, &dev->flags);
1228                        if (fua)
1229                                set_bit(R5_WantFUA, &dev->flags);
1230                        if (sync)
1231                                set_bit(R5_SyncIO, &dev->flags);
1232                }
1233        }
1234
1235        if (sh->reconstruct_state == reconstruct_state_drain_run)
1236                sh->reconstruct_state = reconstruct_state_drain_result;
1237        else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1238                sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1239        else {
1240                BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1241                sh->reconstruct_state = reconstruct_state_result;
1242        }
1243
1244        set_bit(STRIPE_HANDLE, &sh->state);
1245        release_stripe(sh);
1246}
1247
1248static void
1249ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1250                     struct dma_async_tx_descriptor *tx)
1251{
1252        int disks = sh->disks;
1253        struct page **xor_srcs = percpu->scribble;
1254        struct async_submit_ctl submit;
1255        int count = 0, pd_idx = sh->pd_idx, i;
1256        struct page *xor_dest;
1257        int prexor = 0;
1258        unsigned long flags;
1259
1260        pr_debug("%s: stripe %llu\n", __func__,
1261                (unsigned long long)sh->sector);
1262
1263        for (i = 0; i < sh->disks; i++) {
1264                if (pd_idx == i)
1265                        continue;
1266                if (!test_bit(R5_Discard, &sh->dev[i].flags))
1267                        break;
1268        }
1269        if (i >= sh->disks) {
1270                atomic_inc(&sh->count);
1271                set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1272                ops_complete_reconstruct(sh);
1273                return;
1274        }
1275        /* check if prexor is active which means only process blocks
1276         * that are part of a read-modify-write (written)
1277         */
1278        if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1279                prexor = 1;
1280                xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1281                for (i = disks; i--; ) {
1282                        struct r5dev *dev = &sh->dev[i];
1283                        if (dev->written)
1284                                xor_srcs[count++] = dev->page;
1285                }
1286        } else {
1287                xor_dest = sh->dev[pd_idx].page;
1288                for (i = disks; i--; ) {
1289                        struct r5dev *dev = &sh->dev[i];
1290                        if (i != pd_idx)
1291                                xor_srcs[count++] = dev->page;
1292                }
1293        }
1294
1295        /* 1/ if we prexor'd then the dest is reused as a source
1296         * 2/ if we did not prexor then we are redoing the parity
1297         * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1298         * for the synchronous xor case
1299         */
1300        flags = ASYNC_TX_ACK |
1301                (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1302
1303        atomic_inc(&sh->count);
1304
1305        init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1306                          to_addr_conv(sh, percpu));
1307        if (unlikely(count == 1))
1308                tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1309        else
1310                tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1311}
1312
1313static void
1314ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1315                     struct dma_async_tx_descriptor *tx)
1316{
1317        struct async_submit_ctl submit;
1318        struct page **blocks = percpu->scribble;
1319        int count, i;
1320
1321        pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1322
1323        for (i = 0; i < sh->disks; i++) {
1324                if (sh->pd_idx == i || sh->qd_idx == i)
1325                        continue;
1326                if (!test_bit(R5_Discard, &sh->dev[i].flags))
1327                        break;
1328        }
1329        if (i >= sh->disks) {
1330                atomic_inc(&sh->count);
1331                set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1332                set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1333                ops_complete_reconstruct(sh);
1334                return;
1335        }
1336
1337        count = set_syndrome_sources(blocks, sh);
1338
1339        atomic_inc(&sh->count);
1340
1341        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1342                          sh, to_addr_conv(sh, percpu));
1343        async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1344}
1345
1346static void ops_complete_check(void *stripe_head_ref)
1347{
1348        struct stripe_head *sh = stripe_head_ref;
1349
1350        pr_debug("%s: stripe %llu\n", __func__,
1351                (unsigned long long)sh->sector);
1352
1353        sh->check_state = check_state_check_result;
1354        set_bit(STRIPE_HANDLE, &sh->state);
1355        release_stripe(sh);
1356}
1357
1358static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1359{
1360        int disks = sh->disks;
1361        int pd_idx = sh->pd_idx;
1362        int qd_idx = sh->qd_idx;
1363        struct page *xor_dest;
1364        struct page **xor_srcs = percpu->scribble;
1365        struct dma_async_tx_descriptor *tx;
1366        struct async_submit_ctl submit;
1367        int count;
1368        int i;
1369
1370        pr_debug("%s: stripe %llu\n", __func__,
1371                (unsigned long long)sh->sector);
1372
1373        count = 0;
1374        xor_dest = sh->dev[pd_idx].page;
1375        xor_srcs[count++] = xor_dest;
1376        for (i = disks; i--; ) {
1377                if (i == pd_idx || i == qd_idx)
1378                        continue;
1379                xor_srcs[count++] = sh->dev[i].page;
1380        }
1381
1382        init_async_submit(&submit, 0, NULL, NULL, NULL,
1383                          to_addr_conv(sh, percpu));
1384        tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1385                           &sh->ops.zero_sum_result, &submit);
1386
1387        atomic_inc(&sh->count);
1388        init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1389        tx = async_trigger_callback(&submit);
1390}
1391
1392static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1393{
1394        struct page **srcs = percpu->scribble;
1395        struct async_submit_ctl submit;
1396        int count;
1397
1398        pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1399                (unsigned long long)sh->sector, checkp);
1400
1401        count = set_syndrome_sources(srcs, sh);
1402        if (!checkp)
1403                srcs[count] = NULL;
1404
1405        atomic_inc(&sh->count);
1406        init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1407                          sh, to_addr_conv(sh, percpu));
1408        async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1409                           &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1410}
1411
1412static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1413{
1414        int overlap_clear = 0, i, disks = sh->disks;
1415        struct dma_async_tx_descriptor *tx = NULL;
1416        struct r5conf *conf = sh->raid_conf;
1417        int level = conf->level;
1418        struct raid5_percpu *percpu;
1419        unsigned long cpu;
1420
1421        cpu = get_cpu();
1422        percpu = per_cpu_ptr(conf->percpu, cpu);
1423        if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1424                ops_run_biofill(sh);
1425                overlap_clear++;
1426        }
1427
1428        if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1429                if (level < 6)
1430                        tx = ops_run_compute5(sh, percpu);
1431                else {
1432                        if (sh->ops.target2 < 0 || sh->ops.target < 0)
1433                                tx = ops_run_compute6_1(sh, percpu);
1434                        else
1435                                tx = ops_run_compute6_2(sh, percpu);
1436                }
1437                /* terminate the chain if reconstruct is not set to be run */
1438                if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1439                        async_tx_ack(tx);
1440        }
1441
1442        if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1443                tx = ops_run_prexor(sh, percpu, tx);
1444
1445        if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1446                tx = ops_run_biodrain(sh, tx);
1447                overlap_clear++;
1448        }
1449
1450        if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1451                if (level < 6)
1452                        ops_run_reconstruct5(sh, percpu, tx);
1453                else
1454                        ops_run_reconstruct6(sh, percpu, tx);
1455        }
1456
1457        if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1458                if (sh->check_state == check_state_run)
1459                        ops_run_check_p(sh, percpu);
1460                else if (sh->check_state == check_state_run_q)
1461                        ops_run_check_pq(sh, percpu, 0);
1462                else if (sh->check_state == check_state_run_pq)
1463                        ops_run_check_pq(sh, percpu, 1);
1464                else
1465                        BUG();
1466        }
1467
1468        if (overlap_clear)
1469                for (i = disks; i--; ) {
1470                        struct r5dev *dev = &sh->dev[i];
1471                        if (test_and_clear_bit(R5_Overlap, &dev->flags))
1472                                wake_up(&sh->raid_conf->wait_for_overlap);
1473                }
1474        put_cpu();
1475}
1476
1477static int grow_one_stripe(struct r5conf *conf)
1478{
1479        struct stripe_head *sh;
1480        sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1481        if (!sh)
1482                return 0;
1483
1484        sh->raid_conf = conf;
1485
1486        spin_lock_init(&sh->stripe_lock);
1487
1488        if (grow_buffers(sh)) {
1489                shrink_buffers(sh);
1490                kmem_cache_free(conf->slab_cache, sh);
1491                return 0;
1492        }
1493        /* we just created an active stripe so... */
1494        atomic_set(&sh->count, 1);
1495        atomic_inc(&conf->active_stripes);
1496        INIT_LIST_HEAD(&sh->lru);
1497        release_stripe(sh);
1498        return 1;
1499}
1500
1501static int grow_stripes(struct r5conf *conf, int num)
1502{
1503        struct kmem_cache *sc;
1504        int devs = max(conf->raid_disks, conf->previous_raid_disks);
1505
1506        if (conf->mddev->gendisk)
1507                sprintf(conf->cache_name[0],
1508                        "raid%d-%s", conf->level, mdname(conf->mddev));
1509        else
1510                sprintf(conf->cache_name[0],
1511                        "raid%d-%p", conf->level, conf->mddev);
1512        sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1513
1514        conf->active_name = 0;
1515        sc = kmem_cache_create(conf->cache_name[conf->active_name],
1516                               sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1517                               0, 0, NULL);
1518        if (!sc)
1519                return 1;
1520        conf->slab_cache = sc;
1521        conf->pool_size = devs;
1522        while (num--)
1523                if (!grow_one_stripe(conf))
1524                        return 1;
1525        return 0;
1526}
1527
1528/**
1529 * scribble_len - return the required size of the scribble region
1530 * @num - total number of disks in the array
1531 *
1532 * The size must be enough to contain:
1533 * 1/ a struct page pointer for each device in the array +2
1534 * 2/ room to convert each entry in (1) to its corresponding dma
1535 *    (dma_map_page()) or page (page_address()) address.
1536 *
1537 * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1538 * calculate over all devices (not just the data blocks), using zeros in place
1539 * of the P and Q blocks.
1540 */
1541static size_t scribble_len(int num)
1542{
1543        size_t len;
1544
1545        len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1546
1547        return len;
1548}
1549
1550static int resize_stripes(struct r5conf *conf, int newsize)
1551{
1552        /* Make all the stripes able to hold 'newsize' devices.
1553         * New slots in each stripe get 'page' set to a new page.
1554         *
1555         * This happens in stages:
1556         * 1/ create a new kmem_cache and allocate the required number of
1557         *    stripe_heads.
1558         * 2/ gather all the old stripe_heads and transfer the pages across
1559         *    to the new stripe_heads.  This will have the side effect of
1560         *    freezing the array as once all stripe_heads have been collected,
1561         *    no IO will be possible.  Old stripe heads are freed once their
1562         *    pages have been transferred over, and the old kmem_cache is
1563         *    freed when all stripes are done.
1564         * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1565         *    we simple return a failre status - no need to clean anything up.
1566         * 4/ allocate new pages for the new slots in the new stripe_heads.
1567         *    If this fails, we don't bother trying the shrink the
1568         *    stripe_heads down again, we just leave them as they are.
1569         *    As each stripe_head is processed the new one is released into
1570         *    active service.
1571         *
1572         * Once step2 is started, we cannot afford to wait for a write,
1573         * so we use GFP_NOIO allocations.
1574         */
1575        struct stripe_head *osh, *nsh;
1576        LIST_HEAD(newstripes);
1577        struct disk_info *ndisks;
1578        unsigned long cpu;
1579        int err;
1580        struct kmem_cache *sc;
1581        int i;
1582
1583        if (newsize <= conf->pool_size)
1584                return 0; /* never bother to shrink */
1585
1586        err = md_allow_write(conf->mddev);
1587        if (err)
1588                return err;
1589
1590        /* Step 1 */
1591        sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1592                               sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1593                               0, 0, NULL);
1594        if (!sc)
1595                return -ENOMEM;
1596
1597        for (i = conf->max_nr_stripes; i; i--) {
1598                nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1599                if (!nsh)
1600                        break;
1601
1602                nsh->raid_conf = conf;
1603                spin_lock_init(&nsh->stripe_lock);
1604
1605                list_add(&nsh->lru, &newstripes);
1606        }
1607        if (i) {
1608                /* didn't get enough, give up */
1609                while (!list_empty(&newstripes)) {
1610                        nsh = list_entry(newstripes.next, struct stripe_head, lru);
1611                        list_del(&nsh->lru);
1612                        kmem_cache_free(sc, nsh);
1613                }
1614                kmem_cache_destroy(sc);
1615                return -ENOMEM;
1616        }
1617        /* Step 2 - Must use GFP_NOIO now.
1618         * OK, we have enough stripes, start collecting inactive
1619         * stripes and copying them over
1620         */
1621        list_for_each_entry(nsh, &newstripes, lru) {
1622                spin_lock_irq(&conf->device_lock);
1623                wait_event_lock_irq(conf->wait_for_stripe,
1624                                    !list_empty(&conf->inactive_list),
1625                                    conf->device_lock);
1626                osh = get_free_stripe(conf);
1627                spin_unlock_irq(&conf->device_lock);
1628                atomic_set(&nsh->count, 1);
1629                for(i=0; i<conf->pool_size; i++)
1630                        nsh->dev[i].page = osh->dev[i].page;
1631                for( ; i<newsize; i++)
1632                        nsh->dev[i].page = NULL;
1633                kmem_cache_free(conf->slab_cache, osh);
1634        }
1635        kmem_cache_destroy(conf->slab_cache);
1636
1637        /* Step 3.
1638         * At this point, we are holding all the stripes so the array
1639         * is completely stalled, so now is a good time to resize
1640         * conf->disks and the scribble region
1641         */
1642        ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1643        if (ndisks) {
1644                for (i=0; i<conf->raid_disks; i++)
1645                        ndisks[i] = conf->disks[i];
1646                kfree(conf->disks);
1647                conf->disks = ndisks;
1648        } else
1649                err = -ENOMEM;
1650
1651        get_online_cpus();
1652        conf->scribble_len = scribble_len(newsize);
1653        for_each_present_cpu(cpu) {
1654                struct raid5_percpu *percpu;
1655                void *scribble;
1656
1657                percpu = per_cpu_ptr(conf->percpu, cpu);
1658                scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1659
1660                if (scribble) {
1661                        kfree(percpu->scribble);
1662                        percpu->scribble = scribble;
1663                } else {
1664                        err = -ENOMEM;
1665                        break;
1666                }
1667        }
1668        put_online_cpus();
1669
1670        /* Step 4, return new stripes to service */
1671        while(!list_empty(&newstripes)) {
1672                nsh = list_entry(newstripes.next, struct stripe_head, lru);
1673                list_del_init(&nsh->lru);
1674
1675                for (i=conf->raid_disks; i < newsize; i++)
1676                        if (nsh->dev[i].page == NULL) {
1677                                struct page *p = alloc_page(GFP_NOIO);
1678                                nsh->dev[i].page = p;
1679                                if (!p)
1680                                        err = -ENOMEM;
1681                        }
1682                release_stripe(nsh);
1683        }
1684        /* critical section pass, GFP_NOIO no longer needed */
1685
1686        conf->slab_cache = sc;
1687        conf->active_name = 1-conf->active_name;
1688        conf->pool_size = newsize;
1689        return err;
1690}
1691
1692static int drop_one_stripe(struct r5conf *conf)
1693{
1694        struct stripe_head *sh;
1695
1696        spin_lock_irq(&conf->device_lock);
1697        sh = get_free_stripe(conf);
1698        spin_unlock_irq(&conf->device_lock);
1699        if (!sh)
1700                return 0;
1701        BUG_ON(atomic_read(&sh->count));
1702        shrink_buffers(sh);
1703        kmem_cache_free(conf->slab_cache, sh);
1704        atomic_dec(&conf->active_stripes);
1705        return 1;
1706}
1707
1708static void shrink_stripes(struct r5conf *conf)
1709{
1710        while (drop_one_stripe(conf))
1711                ;
1712
1713        if (conf->slab_cache)
1714                kmem_cache_destroy(conf->slab_cache);
1715        conf->slab_cache = NULL;
1716}
1717
1718static void raid5_end_read_request(struct bio * bi, int error)
1719{
1720        struct stripe_head *sh = bi->bi_private;
1721        struct r5conf *conf = sh->raid_conf;
1722        int disks = sh->disks, i;
1723        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1724        char b[BDEVNAME_SIZE];
1725        struct md_rdev *rdev = NULL;
1726        sector_t s;
1727
1728        for (i=0 ; i<disks; i++)
1729                if (bi == &sh->dev[i].req)
1730                        break;
1731
1732        pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1733                (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1734                uptodate);
1735        if (i == disks) {
1736                BUG();
1737                return;
1738        }
1739        if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1740                /* If replacement finished while this request was outstanding,
1741                 * 'replacement' might be NULL already.
1742                 * In that case it moved down to 'rdev'.
1743                 * rdev is not removed until all requests are finished.
1744                 */
1745                rdev = conf->disks[i].replacement;
1746        if (!rdev)
1747                rdev = conf->disks[i].rdev;
1748
1749        if (use_new_offset(conf, sh))
1750                s = sh->sector + rdev->new_data_offset;
1751        else
1752                s = sh->sector + rdev->data_offset;
1753        if (uptodate) {
1754                set_bit(R5_UPTODATE, &sh->dev[i].flags);
1755                if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1756                        /* Note that this cannot happen on a
1757                         * replacement device.  We just fail those on
1758                         * any error
1759                         */
1760                        printk_ratelimited(
1761                                KERN_INFO
1762                                "md/raid:%s: read error corrected"
1763                                " (%lu sectors at %llu on %s)\n",
1764                                mdname(conf->mddev), STRIPE_SECTORS,
1765                                (unsigned long long)s,
1766                                bdevname(rdev->bdev, b));
1767                        atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1768                        clear_bit(R5_ReadError, &sh->dev[i].flags);
1769                        clear_bit(R5_ReWrite, &sh->dev[i].flags);
1770                } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
1771                        clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1772
1773                if (atomic_read(&rdev->read_errors))
1774                        atomic_set(&rdev->read_errors, 0);
1775        } else {
1776                const char *bdn = bdevname(rdev->bdev, b);
1777                int retry = 0;
1778                int set_bad = 0;
1779
1780                clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1781                atomic_inc(&rdev->read_errors);
1782                if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1783                        printk_ratelimited(
1784                                KERN_WARNING
1785                                "md/raid:%s: read error on replacement device "
1786                                "(sector %llu on %s).\n",
1787                                mdname(conf->mddev),
1788                                (unsigned long long)s,
1789                                bdn);
1790                else if (conf->mddev->degraded >= conf->max_degraded) {
1791                        set_bad = 1;
1792                        printk_ratelimited(
1793                                KERN_WARNING
1794                                "md/raid:%s: read error not correctable "
1795                                "(sector %llu on %s).\n",
1796                                mdname(conf->mddev),
1797                                (unsigned long long)s,
1798                                bdn);
1799                } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
1800                        /* Oh, no!!! */
1801                        set_bad = 1;
1802                        printk_ratelimited(
1803                                KERN_WARNING
1804                                "md/raid:%s: read error NOT corrected!! "
1805                                "(sector %llu on %s).\n",
1806                                mdname(conf->mddev),
1807                                (unsigned long long)s,
1808                                bdn);
1809                } else if (atomic_read(&rdev->read_errors)
1810                         > conf->max_nr_stripes)
1811                        printk(KERN_WARNING
1812                               "md/raid:%s: Too many read errors, failing device %s.\n",
1813                               mdname(conf->mddev), bdn);
1814                else
1815                        retry = 1;
1816                if (retry)
1817                        if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
1818                                set_bit(R5_ReadError, &sh->dev[i].flags);
1819                                clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1820                        } else
1821                                set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1822                else {
1823                        clear_bit(R5_ReadError, &sh->dev[i].flags);
1824                        clear_bit(R5_ReWrite, &sh->dev[i].flags);
1825                        if (!(set_bad
1826                              && test_bit(In_sync, &rdev->flags)
1827                              && rdev_set_badblocks(
1828                                      rdev, sh->sector, STRIPE_SECTORS, 0)))
1829                                md_error(conf->mddev, rdev);
1830                }
1831        }
1832        rdev_dec_pending(rdev, conf->mddev);
1833        clear_bit(R5_LOCKED, &sh->dev[i].flags);
1834        set_bit(STRIPE_HANDLE, &sh->state);
1835        release_stripe(sh);
1836}
1837
1838static void raid5_end_write_request(struct bio *bi, int error)
1839{
1840        struct stripe_head *sh = bi->bi_private;
1841        struct r5conf *conf = sh->raid_conf;
1842        int disks = sh->disks, i;
1843        struct md_rdev *uninitialized_var(rdev);
1844        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1845        sector_t first_bad;
1846        int bad_sectors;
1847        int replacement = 0;
1848
1849        for (i = 0 ; i < disks; i++) {
1850                if (bi == &sh->dev[i].req) {
1851                        rdev = conf->disks[i].rdev;
1852                        break;
1853                }
1854                if (bi == &sh->dev[i].rreq) {
1855                        rdev = conf->disks[i].replacement;
1856                        if (rdev)
1857                                replacement = 1;
1858                        else
1859                                /* rdev was removed and 'replacement'
1860                                 * replaced it.  rdev is not removed
1861                                 * until all requests are finished.
1862                                 */
1863                                rdev = conf->disks[i].rdev;
1864                        break;
1865                }
1866        }
1867        pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1868                (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1869                uptodate);
1870        if (i == disks) {
1871                BUG();
1872                return;
1873        }
1874
1875        if (replacement) {
1876                if (!uptodate)
1877                        md_error(conf->mddev, rdev);
1878                else if (is_badblock(rdev, sh->sector,
1879                                     STRIPE_SECTORS,
1880                                     &first_bad, &bad_sectors))
1881                        set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
1882        } else {
1883                if (!uptodate) {
1884                        set_bit(WriteErrorSeen, &rdev->flags);
1885                        set_bit(R5_WriteError, &sh->dev[i].flags);
1886                        if (!test_and_set_bit(WantReplacement, &rdev->flags))
1887                                set_bit(MD_RECOVERY_NEEDED,
1888                                        &rdev->mddev->recovery);
1889                } else if (is_badblock(rdev, sh->sector,
1890                                       STRIPE_SECTORS,
1891                                       &first_bad, &bad_sectors)) {
1892                        set_bit(R5_MadeGood, &sh->dev[i].flags);
1893                        if (test_bit(R5_ReadError, &sh->dev[i].flags))
1894                                /* That was a successful write so make
1895                                 * sure it looks like we already did
1896                                 * a re-write.
1897                                 */
1898                                set_bit(R5_ReWrite, &sh->dev[i].flags);
1899                }
1900        }
1901        rdev_dec_pending(rdev, conf->mddev);
1902
1903        if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
1904                clear_bit(R5_LOCKED, &sh->dev[i].flags);
1905        set_bit(STRIPE_HANDLE, &sh->state);
1906        release_stripe(sh);
1907}
1908
1909static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1910        
1911static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1912{
1913        struct r5dev *dev = &sh->dev[i];
1914
1915        bio_init(&dev->req);
1916        dev->req.bi_io_vec = &dev->vec;
1917        dev->req.bi_vcnt++;
1918        dev->req.bi_max_vecs++;
1919        dev->req.bi_private = sh;
1920        dev->vec.bv_page = dev->page;
1921
1922        bio_init(&dev->rreq);
1923        dev->rreq.bi_io_vec = &dev->rvec;
1924        dev->rreq.bi_vcnt++;
1925        dev->rreq.bi_max_vecs++;
1926        dev->rreq.bi_private = sh;
1927        dev->rvec.bv_page = dev->page;
1928
1929        dev->flags = 0;
1930        dev->sector = compute_blocknr(sh, i, previous);
1931}
1932
1933static void error(struct mddev *mddev, struct md_rdev *rdev)
1934{
1935        char b[BDEVNAME_SIZE];
1936        struct r5conf *conf = mddev->private;
1937        unsigned long flags;
1938        pr_debug("raid456: error called\n");
1939
1940        spin_lock_irqsave(&conf->device_lock, flags);
1941        clear_bit(In_sync, &rdev->flags);
1942        mddev->degraded = calc_degraded(conf);
1943        spin_unlock_irqrestore(&conf->device_lock, flags);
1944        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1945
1946        set_bit(Blocked, &rdev->flags);
1947        set_bit(Faulty, &rdev->flags);
1948        set_bit(MD_CHANGE_DEVS, &mddev->flags);
1949        printk(KERN_ALERT
1950               "md/raid:%s: Disk failure on %s, disabling device.\n"
1951               "md/raid:%s: Operation continuing on %d devices.\n",
1952               mdname(mddev),
1953               bdevname(rdev->bdev, b),
1954               mdname(mddev),
1955               conf->raid_disks - mddev->degraded);
1956}
1957
1958/*
1959 * Input: a 'big' sector number,
1960 * Output: index of the data and parity disk, and the sector # in them.
1961 */
1962static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
1963                                     int previous, int *dd_idx,
1964                                     struct stripe_head *sh)
1965{
1966        sector_t stripe, stripe2;
1967        sector_t chunk_number;
1968        unsigned int chunk_offset;
1969        int pd_idx, qd_idx;
1970        int ddf_layout = 0;
1971        sector_t new_sector;
1972        int algorithm = previous ? conf->prev_algo
1973                                 : conf->algorithm;
1974        int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1975                                         : conf->chunk_sectors;
1976        int raid_disks = previous ? conf->previous_raid_disks
1977                                  : conf->raid_disks;
1978        int data_disks = raid_disks - conf->max_degraded;
1979
1980        /* First compute the information on this sector */
1981
1982        /*
1983         * Compute the chunk number and the sector offset inside the chunk
1984         */
1985        chunk_offset = sector_div(r_sector, sectors_per_chunk);
1986        chunk_number = r_sector;
1987
1988        /*
1989         * Compute the stripe number
1990         */
1991        stripe = chunk_number;
1992        *dd_idx = sector_div(stripe, data_disks);
1993        stripe2 = stripe;
1994        /*
1995         * Select the parity disk based on the user selected algorithm.
1996         */
1997        pd_idx = qd_idx = -1;
1998        switch(conf->level) {
1999        case 4:
2000                pd_idx = data_disks;
2001                break;
2002        case 5:
2003                switch (algorithm) {
2004                case ALGORITHM_LEFT_ASYMMETRIC:
2005                        pd_idx = data_disks - sector_div(stripe2, raid_disks);
2006                        if (*dd_idx >= pd_idx)
2007                                (*dd_idx)++;
2008                        break;
2009                case ALGORITHM_RIGHT_ASYMMETRIC:
2010                        pd_idx = sector_div(stripe2, raid_disks);
2011                        if (*dd_idx >= pd_idx)
2012                                (*dd_idx)++;
2013                        break;
2014                case ALGORITHM_LEFT_SYMMETRIC:
2015                        pd_idx = data_disks - sector_div(stripe2, raid_disks);
2016                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2017                        break;
2018                case ALGORITHM_RIGHT_SYMMETRIC:
2019                        pd_idx = sector_div(stripe2, raid_disks);
2020                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2021                        break;
2022                case ALGORITHM_PARITY_0:
2023                        pd_idx = 0;
2024                        (*dd_idx)++;
2025                        break;
2026                case ALGORITHM_PARITY_N:
2027                        pd_idx = data_disks;
2028                        break;
2029                default:
2030                        BUG();
2031                }
2032                break;
2033        case 6:
2034
2035                switch (algorithm) {
2036                case ALGORITHM_LEFT_ASYMMETRIC:
2037                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2038                        qd_idx = pd_idx + 1;
2039                        if (pd_idx == raid_disks-1) {
2040                                (*dd_idx)++;    /* Q D D D P */
2041                                qd_idx = 0;
2042                        } else if (*dd_idx >= pd_idx)
2043                                (*dd_idx) += 2; /* D D P Q D */
2044                        break;
2045                case ALGORITHM_RIGHT_ASYMMETRIC:
2046                        pd_idx = sector_div(stripe2, raid_disks);
2047                        qd_idx = pd_idx + 1;
2048                        if (pd_idx == raid_disks-1) {
2049                                (*dd_idx)++;    /* Q D D D P */
2050                                qd_idx = 0;
2051                        } else if (*dd_idx >= pd_idx)
2052                                (*dd_idx) += 2; /* D D P Q D */
2053                        break;
2054                case ALGORITHM_LEFT_SYMMETRIC:
2055                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2056                        qd_idx = (pd_idx + 1) % raid_disks;
2057                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2058                        break;
2059                case ALGORITHM_RIGHT_SYMMETRIC:
2060                        pd_idx = sector_div(stripe2, raid_disks);
2061                        qd_idx = (pd_idx + 1) % raid_disks;
2062                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2063                        break;
2064
2065                case ALGORITHM_PARITY_0:
2066                        pd_idx = 0;
2067                        qd_idx = 1;
2068                        (*dd_idx) += 2;
2069                        break;
2070                case ALGORITHM_PARITY_N:
2071                        pd_idx = data_disks;
2072                        qd_idx = data_disks + 1;
2073                        break;
2074
2075                case ALGORITHM_ROTATING_ZERO_RESTART:
2076                        /* Exactly the same as RIGHT_ASYMMETRIC, but or
2077                         * of blocks for computing Q is different.
2078                         */
2079                        pd_idx = sector_div(stripe2, raid_disks);
2080                        qd_idx = pd_idx + 1;
2081                        if (pd_idx == raid_disks-1) {
2082                                (*dd_idx)++;    /* Q D D D P */
2083                                qd_idx = 0;
2084                        } else if (*dd_idx >= pd_idx)
2085                                (*dd_idx) += 2; /* D D P Q D */
2086                        ddf_layout = 1;
2087                        break;
2088
2089                case ALGORITHM_ROTATING_N_RESTART:
2090                        /* Same a left_asymmetric, by first stripe is
2091                         * D D D P Q  rather than
2092                         * Q D D D P
2093                         */
2094                        stripe2 += 1;
2095                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2096                        qd_idx = pd_idx + 1;
2097                        if (pd_idx == raid_disks-1) {
2098                                (*dd_idx)++;    /* Q D D D P */
2099                                qd_idx = 0;
2100                        } else if (*dd_idx >= pd_idx)
2101                                (*dd_idx) += 2; /* D D P Q D */
2102                        ddf_layout = 1;
2103                        break;
2104
2105                case ALGORITHM_ROTATING_N_CONTINUE:
2106                        /* Same as left_symmetric but Q is before P */
2107                        pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2108                        qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2109                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2110                        ddf_layout = 1;
2111                        break;
2112
2113                case ALGORITHM_LEFT_ASYMMETRIC_6:
2114                        /* RAID5 left_asymmetric, with Q on last device */
2115                        pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2116                        if (*dd_idx >= pd_idx)
2117                                (*dd_idx)++;
2118                        qd_idx = raid_disks - 1;
2119                        break;
2120
2121                case ALGORITHM_RIGHT_ASYMMETRIC_6:
2122                        pd_idx = sector_div(stripe2, raid_disks-1);
2123                        if (*dd_idx >= pd_idx)
2124                                (*dd_idx)++;
2125                        qd_idx = raid_disks - 1;
2126                        break;
2127
2128                case ALGORITHM_LEFT_SYMMETRIC_6:
2129                        pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2130                        *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2131                        qd_idx = raid_disks - 1;
2132                        break;
2133
2134                case ALGORITHM_RIGHT_SYMMETRIC_6:
2135                        pd_idx = sector_div(stripe2, raid_disks-1);
2136                        *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2137                        qd_idx = raid_disks - 1;
2138                        break;
2139
2140                case ALGORITHM_PARITY_0_6:
2141                        pd_idx = 0;
2142                        (*dd_idx)++;
2143                        qd_idx = raid_disks - 1;
2144                        break;
2145
2146                default:
2147                        BUG();
2148                }
2149                break;
2150        }
2151
2152        if (sh) {
2153                sh->pd_idx = pd_idx;
2154                sh->qd_idx = qd_idx;
2155                sh->ddf_layout = ddf_layout;
2156        }
2157        /*
2158         * Finally, compute the new sector number
2159         */
2160        new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2161        return new_sector;
2162}
2163
2164
2165static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2166{
2167        struct r5conf *conf = sh->raid_conf;
2168        int raid_disks = sh->disks;
2169        int data_disks = raid_disks - conf->max_degraded;
2170        sector_t new_sector = sh->sector, check;
2171        int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2172                                         : conf->chunk_sectors;
2173        int algorithm = previous ? conf->prev_algo
2174                                 : conf->algorithm;
2175        sector_t stripe;
2176        int chunk_offset;
2177        sector_t chunk_number;
2178        int dummy1, dd_idx = i;
2179        sector_t r_sector;
2180        struct stripe_head sh2;
2181
2182
2183        chunk_offset = sector_div(new_sector, sectors_per_chunk);
2184        stripe = new_sector;
2185
2186        if (i == sh->pd_idx)
2187                return 0;
2188        switch(conf->level) {
2189        case 4: break;
2190        case 5:
2191                switch (algorithm) {
2192                case ALGORITHM_LEFT_ASYMMETRIC:
2193                case ALGORITHM_RIGHT_ASYMMETRIC:
2194                        if (i > sh->pd_idx)
2195                                i--;
2196                        break;
2197                case ALGORITHM_LEFT_SYMMETRIC:
2198                case ALGORITHM_RIGHT_SYMMETRIC:
2199                        if (i < sh->pd_idx)
2200                                i += raid_disks;
2201                        i -= (sh->pd_idx + 1);
2202                        break;
2203                case ALGORITHM_PARITY_0:
2204                        i -= 1;
2205                        break;
2206                case ALGORITHM_PARITY_N:
2207                        break;
2208                default:
2209                        BUG();
2210                }
2211                break;
2212        case 6:
2213                if (i == sh->qd_idx)
2214                        return 0; /* It is the Q disk */
2215                switch (algorithm) {
2216                case ALGORITHM_LEFT_ASYMMETRIC:
2217                case ALGORITHM_RIGHT_ASYMMETRIC:
2218                case ALGORITHM_ROTATING_ZERO_RESTART:
2219                case ALGORITHM_ROTATING_N_RESTART:
2220                        if (sh->pd_idx == raid_disks-1)
2221                                i--;    /* Q D D D P */
2222                        else if (i > sh->pd_idx)
2223                                i -= 2; /* D D P Q D */
2224                        break;
2225                case ALGORITHM_LEFT_SYMMETRIC:
2226                case ALGORITHM_RIGHT_SYMMETRIC:
2227                        if (sh->pd_idx == raid_disks-1)
2228                                i--; /* Q D D D P */
2229                        else {
2230                                /* D D P Q D */
2231                                if (i < sh->pd_idx)
2232                                        i += raid_disks;
2233                                i -= (sh->pd_idx + 2);
2234                        }
2235                        break;
2236                case ALGORITHM_PARITY_0:
2237                        i -= 2;
2238                        break;
2239                case ALGORITHM_PARITY_N:
2240                        break;
2241                case ALGORITHM_ROTATING_N_CONTINUE:
2242                        /* Like left_symmetric, but P is before Q */
2243                        if (sh->pd_idx == 0)
2244                                i--;    /* P D D D Q */
2245                        else {
2246                                /* D D Q P D */
2247                                if (i < sh->pd_idx)
2248                                        i += raid_disks;
2249                                i -= (sh->pd_idx + 1);
2250                        }
2251                        break;
2252                case ALGORITHM_LEFT_ASYMMETRIC_6:
2253                case ALGORITHM_RIGHT_ASYMMETRIC_6:
2254                        if (i > sh->pd_idx)
2255                                i--;
2256                        break;
2257                case ALGORITHM_LEFT_SYMMETRIC_6:
2258                case ALGORITHM_RIGHT_SYMMETRIC_6:
2259                        if (i < sh->pd_idx)
2260                                i += data_disks + 1;
2261                        i -= (sh->pd_idx + 1);
2262                        break;
2263                case ALGORITHM_PARITY_0_6:
2264                        i -= 1;
2265                        break;
2266                default:
2267                        BUG();
2268                }
2269                break;
2270        }
2271
2272        chunk_number = stripe * data_disks + i;
2273        r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2274
2275        check = raid5_compute_sector(conf, r_sector,
2276                                     previous, &dummy1, &sh2);
2277        if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2278                || sh2.qd_idx != sh->qd_idx) {
2279                printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2280                       mdname(conf->mddev));
2281                return 0;
2282        }
2283        return r_sector;
2284}
2285
2286
2287static void
2288schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2289                         int rcw, int expand)
2290{
2291        int i, pd_idx = sh->pd_idx, disks = sh->disks;
2292        struct r5conf *conf = sh->raid_conf;
2293        int level = conf->level;
2294
2295        if (rcw) {
2296
2297                for (i = disks; i--; ) {
2298                        struct r5dev *dev = &sh->dev[i];
2299
2300                        if (dev->towrite) {
2301                                set_bit(R5_LOCKED, &dev->flags);
2302                                set_bit(R5_Wantdrain, &dev->flags);
2303                                if (!expand)
2304                                        clear_bit(R5_UPTODATE, &dev->flags);
2305                                s->locked++;
2306                        }
2307                }
2308                /* if we are not expanding this is a proper write request, and
2309                 * there will be bios with new data to be drained into the
2310                 * stripe cache
2311                 */
2312                if (!expand) {
2313                        if (!s->locked)
2314                                /* False alarm, nothing to do */
2315                                return;
2316                        sh->reconstruct_state = reconstruct_state_drain_run;
2317                        set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2318                } else
2319                        sh->reconstruct_state = reconstruct_state_run;
2320
2321                set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2322
2323                if (s->locked + conf->max_degraded == disks)
2324                        if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2325                                atomic_inc(&conf->pending_full_writes);
2326        } else {
2327                BUG_ON(level == 6);
2328                BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2329                        test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2330
2331                for (i = disks; i--; ) {
2332                        struct r5dev *dev = &sh->dev[i];
2333                        if (i == pd_idx)
2334                                continue;
2335
2336                        if (dev->towrite &&
2337                            (test_bit(R5_UPTODATE, &dev->flags) ||
2338                             test_bit(R5_Wantcompute, &dev->flags))) {
2339                                set_bit(R5_Wantdrain, &dev->flags);
2340                                set_bit(R5_LOCKED, &dev->flags);
2341                                clear_bit(R5_UPTODATE, &dev->flags);
2342                                s->locked++;
2343                        }
2344                }
2345                if (!s->locked)
2346                        /* False alarm - nothing to do */
2347                        return;
2348                sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2349                set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2350                set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2351                set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2352        }
2353
2354        /* keep the parity disk(s) locked while asynchronous operations
2355         * are in flight
2356         */
2357        set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2358        clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2359        s->locked++;
2360
2361        if (level == 6) {
2362                int qd_idx = sh->qd_idx;
2363                struct r5dev *dev = &sh->dev[qd_idx];
2364
2365                set_bit(R5_LOCKED, &dev->flags);
2366                clear_bit(R5_UPTODATE, &dev->flags);
2367                s->locked++;
2368        }
2369
2370        pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2371                __func__, (unsigned long long)sh->sector,
2372                s->locked, s->ops_request);
2373}
2374
2375/*
2376 * Each stripe/dev can have one or more bion attached.
2377 * toread/towrite point to the first in a chain.
2378 * The bi_next chain must be in order.
2379 */
2380static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2381{
2382        struct bio **bip;
2383        struct r5conf *conf = sh->raid_conf;
2384        int firstwrite=0;
2385
2386        pr_debug("adding bi b#%llu to stripe s#%llu\n",
2387                (unsigned long long)bi->bi_sector,
2388                (unsigned long long)sh->sector);
2389
2390        /*
2391         * If several bio share a stripe. The bio bi_phys_segments acts as a
2392         * reference count to avoid race. The reference count should already be
2393         * increased before this function is called (for example, in
2394         * make_request()), so other bio sharing this stripe will not free the
2395         * stripe. If a stripe is owned by one stripe, the stripe lock will
2396         * protect it.
2397         */
2398        spin_lock_irq(&sh->stripe_lock);
2399        if (forwrite) {
2400                bip = &sh->dev[dd_idx].towrite;
2401                if (*bip == NULL)
2402                        firstwrite = 1;
2403        } else
2404                bip = &sh->dev[dd_idx].toread;
2405        while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2406                if (bio_end_sector(*bip) > bi->bi_sector)
2407                        goto overlap;
2408                bip = & (*bip)->bi_next;
2409        }
2410        if (*bip && (*bip)->bi_sector < bio_end_sector(bi))
2411                goto overlap;
2412
2413        BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2414        if (*bip)
2415                bi->bi_next = *bip;
2416        *bip = bi;
2417        raid5_inc_bi_active_stripes(bi);
2418
2419        if (forwrite) {
2420                /* check if page is covered */
2421                sector_t sector = sh->dev[dd_idx].sector;
2422                for (bi=sh->dev[dd_idx].towrite;
2423                     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2424                             bi && bi->bi_sector <= sector;
2425                     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2426                        if (bio_end_sector(bi) >= sector)
2427                                sector = bio_end_sector(bi);
2428                }
2429                if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2430                        set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2431        }
2432
2433        pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2434                (unsigned long long)(*bip)->bi_sector,
2435                (unsigned long long)sh->sector, dd_idx);
2436        spin_unlock_irq(&sh->stripe_lock);
2437
2438        if (conf->mddev->bitmap && firstwrite) {
2439                bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2440                                  STRIPE_SECTORS, 0);
2441                sh->bm_seq = conf->seq_flush+1;
2442                set_bit(STRIPE_BIT_DELAY, &sh->state);
2443        }
2444        return 1;
2445
2446 overlap:
2447        set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2448        spin_unlock_irq(&sh->stripe_lock);
2449        return 0;
2450}
2451
2452static void end_reshape(struct r5conf *conf);
2453
2454static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2455                            struct stripe_head *sh)
2456{
2457        int sectors_per_chunk =
2458                previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2459        int dd_idx;
2460        int chunk_offset = sector_div(stripe, sectors_per_chunk);
2461        int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2462
2463        raid5_compute_sector(conf,
2464                             stripe * (disks - conf->max_degraded)
2465                             *sectors_per_chunk + chunk_offset,
2466                             previous,
2467                             &dd_idx, sh);
2468}
2469
2470static void
2471handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2472                                struct stripe_head_state *s, int disks,
2473                                struct bio **return_bi)
2474{
2475        int i;
2476        for (i = disks; i--; ) {
2477                struct bio *bi;
2478                int bitmap_end = 0;
2479
2480                if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2481                        struct md_rdev *rdev;
2482                        rcu_read_lock();
2483                        rdev = rcu_dereference(conf->disks[i].rdev);
2484                        if (rdev && test_bit(In_sync, &rdev->flags))
2485                                atomic_inc(&rdev->nr_pending);
2486                        else
2487                                rdev = NULL;
2488                        rcu_read_unlock();
2489                        if (rdev) {
2490                                if (!rdev_set_badblocks(
2491                                            rdev,
2492                                            sh->sector,
2493                                            STRIPE_SECTORS, 0))
2494                                        md_error(conf->mddev, rdev);
2495                                rdev_dec_pending(rdev, conf->mddev);
2496                        }
2497                }
2498                spin_lock_irq(&sh->stripe_lock);
2499                /* fail all writes first */
2500                bi = sh->dev[i].towrite;
2501                sh->dev[i].towrite = NULL;
2502                spin_unlock_irq(&sh->stripe_lock);
2503                if (bi)
2504                        bitmap_end = 1;
2505
2506                if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2507                        wake_up(&conf->wait_for_overlap);
2508
2509                while (bi && bi->bi_sector <
2510                        sh->dev[i].sector + STRIPE_SECTORS) {
2511                        struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2512                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
2513                        if (!raid5_dec_bi_active_stripes(bi)) {
2514                                md_write_end(conf->mddev);
2515                                bi->bi_next = *return_bi;
2516                                *return_bi = bi;
2517                        }
2518                        bi = nextbi;
2519                }
2520                if (bitmap_end)
2521                        bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2522                                STRIPE_SECTORS, 0, 0);
2523                bitmap_end = 0;
2524                /* and fail all 'written' */
2525                bi = sh->dev[i].written;
2526                sh->dev[i].written = NULL;
2527                if (bi) bitmap_end = 1;
2528                while (bi && bi->bi_sector <
2529                       sh->dev[i].sector + STRIPE_SECTORS) {
2530                        struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2531                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
2532                        if (!raid5_dec_bi_active_stripes(bi)) {
2533                                md_write_end(conf->mddev);
2534                                bi->bi_next = *return_bi;
2535                                *return_bi = bi;
2536                        }
2537                        bi = bi2;
2538                }
2539
2540                /* fail any reads if this device is non-operational and
2541                 * the data has not reached the cache yet.
2542                 */
2543                if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2544                    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2545                      test_bit(R5_ReadError, &sh->dev[i].flags))) {
2546                        spin_lock_irq(&sh->stripe_lock);
2547                        bi = sh->dev[i].toread;
2548                        sh->dev[i].toread = NULL;
2549                        spin_unlock_irq(&sh->stripe_lock);
2550                        if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2551                                wake_up(&conf->wait_for_overlap);
2552                        while (bi && bi->bi_sector <
2553                               sh->dev[i].sector + STRIPE_SECTORS) {
2554                                struct bio *nextbi =
2555                                        r5_next_bio(bi, sh->dev[i].sector);
2556                                clear_bit(BIO_UPTODATE, &bi->bi_flags);
2557                                if (!raid5_dec_bi_active_stripes(bi)) {
2558                                        bi->bi_next = *return_bi;
2559                                        *return_bi = bi;
2560                                }
2561                                bi = nextbi;
2562                        }
2563                }
2564                if (bitmap_end)
2565                        bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2566                                        STRIPE_SECTORS, 0, 0);
2567                /* If we were in the middle of a write the parity block might
2568                 * still be locked - so just clear all R5_LOCKED flags
2569                 */
2570                clear_bit(R5_LOCKED, &sh->dev[i].flags);
2571        }
2572
2573        if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2574                if (atomic_dec_and_test(&conf->pending_full_writes))
2575                        md_wakeup_thread(conf->mddev->thread);
2576}
2577
2578static void
2579handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2580                   struct stripe_head_state *s)
2581{
2582        int abort = 0;
2583        int i;
2584
2585        clear_bit(STRIPE_SYNCING, &sh->state);
2586        if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
2587                wake_up(&conf->wait_for_overlap);
2588        s->syncing = 0;
2589        s->replacing = 0;
2590        /* There is nothing more to do for sync/check/repair.
2591         * Don't even need to abort as that is handled elsewhere
2592         * if needed, and not always wanted e.g. if there is a known
2593         * bad block here.
2594         * For recover/replace we need to record a bad block on all
2595         * non-sync devices, or abort the recovery
2596         */
2597        if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2598                /* During recovery devices cannot be removed, so
2599                 * locking and refcounting of rdevs is not needed
2600                 */
2601                for (i = 0; i < conf->raid_disks; i++) {
2602                        struct md_rdev *rdev = conf->disks[i].rdev;
2603                        if (rdev
2604                            && !test_bit(Faulty, &rdev->flags)
2605                            && !test_bit(In_sync, &rdev->flags)
2606                            && !rdev_set_badblocks(rdev, sh->sector,
2607                                                   STRIPE_SECTORS, 0))
2608                                abort = 1;
2609                        rdev = conf->disks[i].replacement;
2610                        if (rdev
2611                            && !test_bit(Faulty, &rdev->flags)
2612                            && !test_bit(In_sync, &rdev->flags)
2613                            && !rdev_set_badblocks(rdev, sh->sector,
2614                                                   STRIPE_SECTORS, 0))
2615                                abort = 1;
2616                }
2617                if (abort)
2618                        conf->recovery_disabled =
2619                                conf->mddev->recovery_disabled;
2620        }
2621        md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2622}
2623
2624static int want_replace(struct stripe_head *sh, int disk_idx)
2625{
2626        struct md_rdev *rdev;
2627        int rv = 0;
2628        /* Doing recovery so rcu locking not required */
2629        rdev = sh->raid_conf->disks[disk_idx].replacement;
2630        if (rdev
2631            && !test_bit(Faulty, &rdev->flags)
2632            && !test_bit(In_sync, &rdev->flags)
2633            && (rdev->recovery_offset <= sh->sector
2634                || rdev->mddev->recovery_cp <= sh->sector))
2635                rv = 1;
2636
2637        return rv;
2638}
2639
2640/* fetch_block - checks the given member device to see if its data needs
2641 * to be read or computed to satisfy a request.
2642 *
2643 * Returns 1 when no more member devices need to be checked, otherwise returns
2644 * 0 to tell the loop in handle_stripe_fill to continue
2645 */
2646static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2647                       int disk_idx, int disks)
2648{
2649        struct r5dev *dev = &sh->dev[disk_idx];
2650        struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2651                                  &sh->dev[s->failed_num[1]] };
2652
2653        /* is the data in this block needed, and can we get it? */
2654        if (!test_bit(R5_LOCKED, &dev->flags) &&
2655            !test_bit(R5_UPTODATE, &dev->flags) &&
2656            (dev->toread ||
2657             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2658             s->syncing || s->expanding ||
2659             (s->replacing && want_replace(sh, disk_idx)) ||
2660             (s->failed >= 1 && fdev[0]->toread) ||
2661             (s->failed >= 2 && fdev[1]->toread) ||
2662             (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2663              !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2664             (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
2665                /* we would like to get this block, possibly by computing it,
2666                 * otherwise read it if the backing disk is insync
2667                 */
2668                BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2669                BUG_ON(test_bit(R5_Wantread, &dev->flags));
2670                if ((s->uptodate == disks - 1) &&
2671                    (s->failed && (disk_idx == s->failed_num[0] ||
2672                                   disk_idx == s->failed_num[1]))) {
2673                        /* have disk failed, and we're requested to fetch it;
2674                         * do compute it
2675                         */
2676                        pr_debug("Computing stripe %llu block %d\n",
2677                               (unsigned long long)sh->sector, disk_idx);
2678                        set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2679                        set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2680                        set_bit(R5_Wantcompute, &dev->flags);
2681                        sh->ops.target = disk_idx;
2682                        sh->ops.target2 = -1; /* no 2nd target */
2683                        s->req_compute = 1;
2684                        /* Careful: from this point on 'uptodate' is in the eye
2685                         * of raid_run_ops which services 'compute' operations
2686                         * before writes. R5_Wantcompute flags a block that will
2687                         * be R5_UPTODATE by the time it is needed for a
2688                         * subsequent operation.
2689                         */
2690                        s->uptodate++;
2691                        return 1;
2692                } else if (s->uptodate == disks-2 && s->failed >= 2) {
2693                        /* Computing 2-failure is *very* expensive; only
2694                         * do it if failed >= 2
2695                         */
2696                        int other;
2697                        for (other = disks; other--; ) {
2698                                if (other == disk_idx)
2699                                        continue;
2700                                if (!test_bit(R5_UPTODATE,
2701                                      &sh->dev[other].flags))
2702                                        break;
2703                        }
2704                        BUG_ON(other < 0);
2705                        pr_debug("Computing stripe %llu blocks %d,%d\n",
2706                               (unsigned long long)sh->sector,
2707                               disk_idx, other);
2708                        set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2709                        set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2710                        set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2711                        set_bit(R5_Wantcompute, &sh->dev[other].flags);
2712                        sh->ops.target = disk_idx;
2713                        sh->ops.target2 = other;
2714                        s->uptodate += 2;
2715                        s->req_compute = 1;
2716                        return 1;
2717                } else if (test_bit(R5_Insync, &dev->flags)) {
2718                        set_bit(R5_LOCKED, &dev->flags);
2719                        set_bit(R5_Wantread, &dev->flags);
2720                        s->locked++;
2721                        pr_debug("Reading block %d (sync=%d)\n",
2722                                disk_idx, s->syncing);
2723                }
2724        }
2725
2726        return 0;
2727}
2728
2729/**
2730 * handle_stripe_fill - read or compute data to satisfy pending requests.
2731 */
2732static void handle_stripe_fill(struct stripe_head *sh,
2733                               struct stripe_head_state *s,
2734                               int disks)
2735{
2736        int i;
2737
2738        /* look for blocks to read/compute, skip this if a compute
2739         * is already in flight, or if the stripe contents are in the
2740         * midst of changing due to a write
2741         */
2742        if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2743            !sh->reconstruct_state)
2744                for (i = disks; i--; )
2745                        if (fetch_block(sh, s, i, disks))
2746                                break;
2747        set_bit(STRIPE_HANDLE, &sh->state);
2748}
2749
2750
2751/* handle_stripe_clean_event
2752 * any written block on an uptodate or failed drive can be returned.
2753 * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2754 * never LOCKED, so we don't need to test 'failed' directly.
2755 */
2756static void handle_stripe_clean_event(struct r5conf *conf,
2757        struct stripe_head *sh, int disks, struct bio **return_bi)
2758{
2759        int i;
2760        struct r5dev *dev;
2761        int discard_pending = 0;
2762
2763        for (i = disks; i--; )
2764                if (sh->dev[i].written) {
2765                        dev = &sh->dev[i];
2766                        if (!test_bit(R5_LOCKED, &dev->flags) &&
2767                            (test_bit(R5_UPTODATE, &dev->flags) ||
2768                             test_bit(R5_Discard, &dev->flags))) {
2769                                /* We can return any write requests */
2770                                struct bio *wbi, *wbi2;
2771                                pr_debug("Return write for disc %d\n", i);
2772                                if (test_and_clear_bit(R5_Discard, &dev->flags))
2773                                        clear_bit(R5_UPTODATE, &dev->flags);
2774                                wbi = dev->written;
2775                                dev->written = NULL;
2776                                while (wbi && wbi->bi_sector <
2777                                        dev->sector + STRIPE_SECTORS) {
2778                                        wbi2 = r5_next_bio(wbi, dev->sector);
2779                                        if (!raid5_dec_bi_active_stripes(wbi)) {
2780                                                md_write_end(conf->mddev);
2781                                                wbi->bi_next = *return_bi;
2782                                                *return_bi = wbi;
2783                                        }
2784                                        wbi = wbi2;
2785                                }
2786                                bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2787                                                STRIPE_SECTORS,
2788                                         !test_bit(STRIPE_DEGRADED, &sh->state),
2789                                                0);
2790                        } else if (test_bit(R5_Discard, &dev->flags))
2791                                discard_pending = 1;
2792                }
2793        if (!discard_pending &&
2794            test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
2795                clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
2796                clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2797                if (sh->qd_idx >= 0) {
2798                        clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
2799                        clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
2800                }
2801                /* now that discard is done we can proceed with any sync */
2802                clear_bit(STRIPE_DISCARD, &sh->state);
2803                if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
2804                        set_bit(STRIPE_HANDLE, &sh->state);
2805
2806        }
2807
2808        if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2809                if (atomic_dec_and_test(&conf->pending_full_writes))
2810                        md_wakeup_thread(conf->mddev->thread);
2811}
2812
2813static void handle_stripe_dirtying(struct r5conf *conf,
2814                                   struct stripe_head *sh,
2815                                   struct stripe_head_state *s,
2816                                   int disks)
2817{
2818        int rmw = 0, rcw = 0, i;
2819        sector_t recovery_cp = conf->mddev->recovery_cp;
2820
2821        /* RAID6 requires 'rcw' in current implementation.
2822         * Otherwise, check whether resync is now happening or should start.
2823         * If yes, then the array is dirty (after unclean shutdown or
2824         * initial creation), so parity in some stripes might be inconsistent.
2825         * In this case, we need to always do reconstruct-write, to ensure
2826         * that in case of drive failure or read-error correction, we
2827         * generate correct data from the parity.
2828         */
2829        if (conf->max_degraded == 2 ||
2830            (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
2831                /* Calculate the real rcw later - for now make it
2832                 * look like rcw is cheaper
2833                 */
2834                rcw = 1; rmw = 2;
2835                pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
2836                         conf->max_degraded, (unsigned long long)recovery_cp,
2837                         (unsigned long long)sh->sector);
2838        } else for (i = disks; i--; ) {
2839                /* would I have to read this buffer for read_modify_write */
2840                struct r5dev *dev = &sh->dev[i];
2841                if ((dev->towrite || i == sh->pd_idx) &&
2842                    !test_bit(R5_LOCKED, &dev->flags) &&
2843                    !(test_bit(R5_UPTODATE, &dev->flags) ||
2844                      test_bit(R5_Wantcompute, &dev->flags))) {
2845                        if (test_bit(R5_Insync, &dev->flags))
2846                                rmw++;
2847                        else
2848                                rmw += 2*disks;  /* cannot read it */
2849                }
2850                /* Would I have to read this buffer for reconstruct_write */
2851                if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2852                    !test_bit(R5_LOCKED, &dev->flags) &&
2853                    !(test_bit(R5_UPTODATE, &dev->flags) ||
2854                    test_bit(R5_Wantcompute, &dev->flags))) {
2855                        if (test_bit(R5_Insync, &dev->flags)) rcw++;
2856                        else
2857                                rcw += 2*disks;
2858                }
2859        }
2860        pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2861                (unsigned long long)sh->sector, rmw, rcw);
2862        set_bit(STRIPE_HANDLE, &sh->state);
2863        if (rmw < rcw && rmw > 0) {
2864                /* prefer read-modify-write, but need to get some data */
2865                if (conf->mddev->queue)
2866                        blk_add_trace_msg(conf->mddev->queue,
2867                                          "raid5 rmw %llu %d",
2868                                          (unsigned long long)sh->sector, rmw);
2869                for (i = disks; i--; ) {
2870                        struct r5dev *dev = &sh->dev[i];
2871                        if ((dev->towrite || i == sh->pd_idx) &&
2872                            !test_bit(R5_LOCKED, &dev->flags) &&
2873                            !(test_bit(R5_UPTODATE, &dev->flags) ||
2874                            test_bit(R5_Wantcompute, &dev->flags)) &&
2875                            test_bit(R5_Insync, &dev->flags)) {
2876                                if (
2877                                  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2878                                        pr_debug("Read_old block "
2879                                                 "%d for r-m-w\n", i);
2880                                        set_bit(R5_LOCKED, &dev->flags);
2881                                        set_bit(R5_Wantread, &dev->flags);
2882                                        s->locked++;
2883                                } else {
2884                                        set_bit(STRIPE_DELAYED, &sh->state);
2885                                        set_bit(STRIPE_HANDLE, &sh->state);
2886                                }
2887                        }
2888                }
2889        }
2890        if (rcw <= rmw && rcw > 0) {
2891                /* want reconstruct write, but need to get some data */
2892                int qread =0;
2893                rcw = 0;
2894                for (i = disks; i--; ) {
2895                        struct r5dev *dev = &sh->dev[i];
2896                        if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2897                            i != sh->pd_idx && i != sh->qd_idx &&
2898                            !test_bit(R5_LOCKED, &dev->flags) &&
2899                            !(test_bit(R5_UPTODATE, &dev->flags) ||
2900                              test_bit(R5_Wantcompute, &dev->flags))) {
2901                                rcw++;
2902                                if (!test_bit(R5_Insync, &dev->flags))
2903                                        continue; /* it's a failed drive */
2904                                if (
2905                                  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2906                                        pr_debug("Read_old block "
2907                                                "%d for Reconstruct\n", i);
2908                                        set_bit(R5_LOCKED, &dev->flags);
2909                                        set_bit(R5_Wantread, &dev->flags);
2910                                        s->locked++;
2911                                        qread++;
2912                                } else {
2913                                        set_bit(STRIPE_DELAYED, &sh->state);
2914                                        set_bit(STRIPE_HANDLE, &sh->state);
2915                                }
2916                        }
2917                }
2918                if (rcw && conf->mddev->queue)
2919                        blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
2920                                          (unsigned long long)sh->sector,
2921                                          rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
2922        }
2923        /* now if nothing is locked, and if we have enough data,
2924         * we can start a write request
2925         */
2926        /* since handle_stripe can be called at any time we need to handle the
2927         * case where a compute block operation has been submitted and then a
2928         * subsequent call wants to start a write request.  raid_run_ops only
2929         * handles the case where compute block and reconstruct are requested
2930         * simultaneously.  If this is not the case then new writes need to be
2931         * held off until the compute completes.
2932         */
2933        if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2934            (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2935            !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2936                schedule_reconstruction(sh, s, rcw == 0, 0);
2937}
2938
2939static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
2940                                struct stripe_head_state *s, int disks)
2941{
2942        struct r5dev *dev = NULL;
2943
2944        set_bit(STRIPE_HANDLE, &sh->state);
2945
2946        switch (sh->check_state) {
2947        case check_state_idle:
2948                /* start a new check operation if there are no failures */
2949                if (s->failed == 0) {
2950                        BUG_ON(s->uptodate != disks);
2951                        sh->check_state = check_state_run;
2952                        set_bit(STRIPE_OP_CHECK, &s->ops_request);
2953                        clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2954                        s->uptodate--;
2955                        break;
2956                }
2957                dev = &sh->dev[s->failed_num[0]];
2958                /* fall through */
2959        case check_state_compute_result:
2960                sh->check_state = check_state_idle;
2961                if (!dev)
2962                        dev = &sh->dev[sh->pd_idx];
2963
2964                /* check that a write has not made the stripe insync */
2965                if (test_bit(STRIPE_INSYNC, &sh->state))
2966                        break;
2967
2968                /* either failed parity check, or recovery is happening */
2969                BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2970                BUG_ON(s->uptodate != disks);
2971
2972                set_bit(R5_LOCKED, &dev->flags);
2973                s->locked++;
2974                set_bit(R5_Wantwrite, &dev->flags);
2975
2976                clear_bit(STRIPE_DEGRADED, &sh->state);
2977                set_bit(STRIPE_INSYNC, &sh->state);
2978                break;
2979        case check_state_run:
2980                break; /* we will be called again upon completion */
2981        case check_state_check_result:
2982                sh->check_state = check_state_idle;
2983
2984                /* if a failure occurred during the check operation, leave
2985                 * STRIPE_INSYNC not set and let the stripe be handled again
2986                 */
2987                if (s->failed)
2988                        break;
2989
2990                /* handle a successful check operation, if parity is correct
2991                 * we are done.  Otherwise update the mismatch count and repair
2992                 * parity if !MD_RECOVERY_CHECK
2993                 */
2994                if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
2995                        /* parity is correct (on disc,
2996                         * not in buffer any more)
2997                         */
2998                        set_bit(STRIPE_INSYNC, &sh->state);
2999                else {
3000                        atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3001                        if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3002                                /* don't try to repair!! */
3003                                set_bit(STRIPE_INSYNC, &sh->state);
3004                        else {
3005                                sh->check_state = check_state_compute_run;
3006                                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3007                                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3008                                set_bit(R5_Wantcompute,
3009                                        &sh->dev[sh->pd_idx].flags);
3010                                sh->ops.target = sh->pd_idx;
3011                                sh->ops.target2 = -1;
3012                                s->uptodate++;
3013                        }
3014                }
3015                break;
3016        case check_state_compute_run:
3017                break;
3018        default:
3019                printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3020                       __func__, sh->check_state,
3021                       (unsigned long long) sh->sector);
3022                BUG();
3023        }
3024}
3025
3026
3027static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3028                                  struct stripe_head_state *s,
3029                                  int disks)
3030{
3031        int pd_idx = sh->pd_idx;
3032        int qd_idx = sh->qd_idx;
3033        struct r5dev *dev;
3034
3035        set_bit(STRIPE_HANDLE, &sh->state);
3036
3037        BUG_ON(s->failed > 2);
3038
3039        /* Want to check and possibly repair P and Q.
3040         * However there could be one 'failed' device, in which
3041         * case we can only check one of them, possibly using the
3042         * other to generate missing data
3043         */
3044
3045        switch (sh->check_state) {
3046        case check_state_idle:
3047                /* start a new check operation if there are < 2 failures */
3048                if (s->failed == s->q_failed) {
3049                        /* The only possible failed device holds Q, so it
3050                         * makes sense to check P (If anything else were failed,
3051                         * we would have used P to recreate it).
3052                         */
3053                        sh->check_state = check_state_run;
3054                }
3055                if (!s->q_failed && s->failed < 2) {
3056                        /* Q is not failed, and we didn't use it to generate
3057                         * anything, so it makes sense to check it
3058                         */
3059                        if (sh->check_state == check_state_run)
3060                                sh->check_state = check_state_run_pq;
3061                        else
3062                                sh->check_state = check_state_run_q;
3063                }
3064
3065                /* discard potentially stale zero_sum_result */
3066                sh->ops.zero_sum_result = 0;
3067
3068                if (sh->check_state == check_state_run) {
3069                        /* async_xor_zero_sum destroys the contents of P */
3070                        clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3071                        s->uptodate--;
3072                }
3073                if (sh->check_state >= check_state_run &&
3074                    sh->check_state <= check_state_run_pq) {
3075                        /* async_syndrome_zero_sum preserves P and Q, so
3076                         * no need to mark them !uptodate here
3077                         */
3078                        set_bit(STRIPE_OP_CHECK, &s->ops_request);
3079                        break;
3080                }
3081
3082                /* we have 2-disk failure */
3083                BUG_ON(s->failed != 2);
3084                /* fall through */
3085        case check_state_compute_result:
3086                sh->check_state = check_state_idle;
3087
3088                /* check that a write has not made the stripe insync */
3089                if (test_bit(STRIPE_INSYNC, &sh->state))
3090                        break;
3091
3092                /* now write out any block on a failed drive,
3093                 * or P or Q if they were recomputed
3094                 */
3095                BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3096                if (s->failed == 2) {
3097                        dev = &sh->dev[s->failed_num[1]];
3098                        s->locked++;
3099                        set_bit(R5_LOCKED, &dev->flags);
3100                        set_bit(R5_Wantwrite, &dev->flags);
3101                }
3102                if (s->failed >= 1) {
3103                        dev = &sh->dev[s->failed_num[0]];
3104                        s->locked++;
3105                        set_bit(R5_LOCKED, &dev->flags);
3106                        set_bit(R5_Wantwrite, &dev->flags);
3107                }
3108                if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3109                        dev = &sh->dev[pd_idx];
3110                        s->locked++;
3111                        set_bit(R5_LOCKED, &dev->flags);
3112                        set_bit(R5_Wantwrite, &dev->flags);
3113                }
3114                if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3115                        dev = &sh->dev[qd_idx];
3116                        s->locked++;
3117                        set_bit(R5_LOCKED, &dev->flags);
3118                        set_bit(R5_Wantwrite, &dev->flags);
3119                }
3120                clear_bit(STRIPE_DEGRADED, &sh->state);
3121
3122                set_bit(STRIPE_INSYNC, &sh->state);
3123                break;
3124        case check_state_run:
3125        case check_state_run_q:
3126        case check_state_run_pq:
3127                break; /* we will be called again upon completion */
3128        case check_state_check_result:
3129                sh->check_state = check_state_idle;
3130
3131                /* handle a successful check operation, if parity is correct
3132                 * we are done.  Otherwise update the mismatch count and repair
3133                 * parity if !MD_RECOVERY_CHECK
3134                 */
3135                if (sh->ops.zero_sum_result == 0) {
3136                        /* both parities are correct */
3137                        if (!s->failed)
3138                                set_bit(STRIPE_INSYNC, &sh->state);
3139                        else {
3140                                /* in contrast to the raid5 case we can validate
3141                                 * parity, but still have a failure to write
3142                                 * back
3143                                 */
3144                                sh->check_state = check_state_compute_result;
3145                                /* Returning at this point means that we may go
3146                                 * off and bring p and/or q uptodate again so
3147                                 * we make sure to check zero_sum_result again
3148                                 * to verify if p or q need writeback
3149                                 */
3150                        }
3151                } else {
3152                        atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3153                        if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3154                                /* don't try to repair!! */
3155                                set_bit(STRIPE_INSYNC, &sh->state);
3156                        else {
3157                                int *target = &sh->ops.target;
3158
3159                                sh->ops.target = -1;
3160                                sh->ops.target2 = -1;
3161                                sh->check_state = check_state_compute_run;
3162                                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3163                                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3164                                if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3165                                        set_bit(R5_Wantcompute,
3166                                                &sh->dev[pd_idx].flags);
3167                                        *target = pd_idx;
3168                                        target = &sh->ops.target2;
3169                                        s->uptodate++;
3170                                }
3171                                if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3172                                        set_bit(R5_Wantcompute,
3173                                                &sh->dev[qd_idx].flags);
3174                                        *target = qd_idx;
3175                                        s->uptodate++;
3176                                }
3177                        }
3178                }
3179                break;
3180        case check_state_compute_run:
3181                break;
3182        default:
3183                printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3184                       __func__, sh->check_state,
3185                       (unsigned long long) sh->sector);
3186                BUG();
3187        }
3188}
3189
3190static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3191{
3192        int i;
3193
3194        /* We have read all the blocks in this stripe and now we need to
3195         * copy some of them into a target stripe for expand.
3196         */
3197        struct dma_async_tx_descriptor *tx = NULL;
3198        clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3199        for (i = 0; i < sh->disks; i++)
3200                if (i != sh->pd_idx && i != sh->qd_idx) {
3201                        int dd_idx, j;
3202                        struct stripe_head *sh2;
3203                        struct async_submit_ctl submit;
3204
3205                        sector_t bn = compute_blocknr(sh, i, 1);
3206                        sector_t s = raid5_compute_sector(conf, bn, 0,
3207                                                          &dd_idx, NULL);
3208                        sh2 = get_active_stripe(conf, s, 0, 1, 1);
3209                        if (sh2 == NULL)
3210                                /* so far only the early blocks of this stripe
3211                                 * have been requested.  When later blocks
3212                                 * get requested, we will try again
3213                                 */
3214                                continue;
3215                        if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3216                           test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3217                                /* must have already done this block */
3218                                release_stripe(sh2);
3219                                continue;
3220                        }
3221
3222                        /* place all the copies on one channel */
3223                        init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3224                        tx = async_memcpy(sh2->dev[dd_idx].page,
3225                                          sh->dev[i].page, 0, 0, STRIPE_SIZE,
3226                                          &submit);
3227
3228                        set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3229                        set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3230                        for (j = 0; j < conf->raid_disks; j++)
3231                                if (j != sh2->pd_idx &&
3232                                    j != sh2->qd_idx &&
3233                                    !test_bit(R5_Expanded, &sh2->dev[j].flags))
3234                                        break;
3235                        if (j == conf->raid_disks) {
3236                                set_bit(STRIPE_EXPAND_READY, &sh2->state);
3237                                set_bit(STRIPE_HANDLE, &sh2->state);
3238                        }
3239                        release_stripe(sh2);
3240
3241                }
3242        /* done submitting copies, wait for them to complete */
3243        async_tx_quiesce(&tx);
3244}
3245
3246/*
3247 * handle_stripe - do things to a stripe.
3248 *
3249 * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3250 * state of various bits to see what needs to be done.
3251 * Possible results:
3252 *    return some read requests which now have data
3253 *    return some write requests which are safely on storage
3254 *    schedule a read on some buffers
3255 *    schedule a write of some buffers
3256 *    return confirmation of parity correctness
3257 *
3258 */
3259
3260static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3261{
3262        struct r5conf *conf = sh->raid_conf;
3263        int disks = sh->disks;
3264        struct r5dev *dev;
3265        int i;
3266        int do_recovery = 0;
3267
3268        memset(s, 0, sizeof(*s));
3269
3270        s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3271        s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3272        s->failed_num[0] = -1;
3273        s->failed_num[1] = -1;
3274
3275        /* Now to look around and see what can be done */
3276        rcu_read_lock();
3277        for (i=disks; i--; ) {
3278                struct md_rdev *rdev;
3279                sector_t first_bad;
3280                int bad_sectors;
3281                int is_bad = 0;
3282
3283                dev = &sh->dev[i];
3284
3285                pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3286                         i, dev->flags,
3287                         dev->toread, dev->towrite, dev->written);
3288                /* maybe we can reply to a read
3289                 *
3290                 * new wantfill requests are only permitted while
3291                 * ops_complete_biofill is guaranteed to be inactive
3292                 */
3293                if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3294                    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3295                        set_bit(R5_Wantfill, &dev->flags);
3296
3297                /* now count some things */
3298                if (test_bit(R5_LOCKED, &dev->flags))
3299                        s->locked++;
3300                if (test_bit(R5_UPTODATE, &dev->flags))
3301                        s->uptodate++;
3302                if (test_bit(R5_Wantcompute, &dev->flags)) {
3303                        s->compute++;
3304                        BUG_ON(s->compute > 2);
3305                }
3306
3307                if (test_bit(R5_Wantfill, &dev->flags))
3308                        s->to_fill++;
3309                else if (dev->toread)
3310                        s->to_read++;
3311                if (dev->towrite) {
3312                        s->to_write++;
3313                        if (!test_bit(R5_OVERWRITE, &dev->flags))
3314                                s->non_overwrite++;
3315                }
3316                if (dev->written)
3317                        s->written++;
3318                /* Prefer to use the replacement for reads, but only
3319                 * if it is recovered enough and has no bad blocks.
3320                 */
3321                rdev = rcu_dereference(conf->disks[i].replacement);
3322                if (rdev && !test_bit(Faulty, &rdev->flags) &&
3323                    rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3324                    !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3325                                 &first_bad, &bad_sectors))
3326                        set_bit(R5_ReadRepl, &dev->flags);
3327                else {
3328                        if (rdev)
3329                                set_bit(R5_NeedReplace, &dev->flags);
3330                        rdev = rcu_dereference(conf->disks[i].rdev);
3331                        clear_bit(R5_ReadRepl, &dev->flags);
3332                }
3333                if (rdev && test_bit(Faulty, &rdev->flags))
3334                        rdev = NULL;
3335                if (rdev) {
3336                        is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3337                                             &first_bad, &bad_sectors);
3338                        if (s->blocked_rdev == NULL
3339                            && (test_bit(Blocked, &rdev->flags)
3340                                || is_bad < 0)) {
3341                                if (is_bad < 0)
3342                                        set_bit(BlockedBadBlocks,
3343                                                &rdev->flags);
3344                                s->blocked_rdev = rdev;
3345                                atomic_inc(&rdev->nr_pending);
3346                        }
3347                }
3348                clear_bit(R5_Insync, &dev->flags);
3349                if (!rdev)
3350                        /* Not in-sync */;
3351                else if (is_bad) {
3352                        /* also not in-sync */
3353                        if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3354                            test_bit(R5_UPTODATE, &dev->flags)) {
3355                                /* treat as in-sync, but with a read error
3356                                 * which we can now try to correct
3357                                 */
3358                                set_bit(R5_Insync, &dev->flags);
3359                                set_bit(R5_ReadError, &dev->flags);
3360                        }
3361                } else if (test_bit(In_sync, &rdev->flags))
3362                        set_bit(R5_Insync, &dev->flags);
3363                else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3364                        /* in sync if before recovery_offset */
3365                        set_bit(R5_Insync, &dev->flags);
3366                else if (test_bit(R5_UPTODATE, &dev->flags) &&
3367                         test_bit(R5_Expanded, &dev->flags))
3368                        /* If we've reshaped into here, we assume it is Insync.
3369                         * We will shortly update recovery_offset to make
3370                         * it official.
3371                         */
3372                        set_bit(R5_Insync, &dev->flags);
3373
3374                if (rdev && test_bit(R5_WriteError, &dev->flags)) {
3375                        /* This flag does not apply to '.replacement'
3376                         * only to .rdev, so make sure to check that*/
3377                        struct md_rdev *rdev2 = rcu_dereference(
3378                                conf->disks[i].rdev);
3379                        if (rdev2 == rdev)
3380                                clear_bit(R5_Insync, &dev->flags);
3381                        if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3382                                s->handle_bad_blocks = 1;
3383                                atomic_inc(&rdev2->nr_pending);
3384                        } else
3385                                clear_bit(R5_WriteError, &dev->flags);
3386                }
3387                if (rdev && test_bit(R5_MadeGood, &dev->flags)) {
3388                        /* This flag does not apply to '.replacement'
3389                         * only to .rdev, so make sure to check that*/
3390                        struct md_rdev *rdev2 = rcu_dereference(
3391                                conf->disks[i].rdev);
3392                        if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3393                                s->handle_bad_blocks = 1;
3394                                atomic_inc(&rdev2->nr_pending);
3395                        } else
3396                                clear_bit(R5_MadeGood, &dev->flags);
3397                }
3398                if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3399                        struct md_rdev *rdev2 = rcu_dereference(
3400                                conf->disks[i].replacement);
3401                        if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3402                                s->handle_bad_blocks = 1;
3403                                atomic_inc(&rdev2->nr_pending);
3404                        } else
3405                                clear_bit(R5_MadeGoodRepl, &dev->flags);
3406                }
3407                if (!test_bit(R5_Insync, &dev->flags)) {
3408                        /* The ReadError flag will just be confusing now */
3409                        clear_bit(R5_ReadError, &dev->flags);
3410                        clear_bit(R5_ReWrite, &dev->flags);
3411                }
3412                if (test_bit(R5_ReadError, &dev->flags))
3413                        clear_bit(R5_Insync, &dev->flags);
3414                if (!test_bit(R5_Insync, &dev->flags)) {
3415                        if (s->failed < 2)
3416                                s->failed_num[s->failed] = i;
3417                        s->failed++;
3418                        if (rdev && !test_bit(Faulty, &rdev->flags))
3419                                do_recovery = 1;
3420                }
3421        }
3422        if (test_bit(STRIPE_SYNCING, &sh->state)) {
3423                /* If there is a failed device being replaced,
3424                 *     we must be recovering.
3425                 * else if we are after recovery_cp, we must be syncing
3426                 * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3427                 * else we can only be replacing
3428                 * sync and recovery both need to read all devices, and so
3429                 * use the same flag.
3430                 */
3431                if (do_recovery ||
3432                    sh->sector >= conf->mddev->recovery_cp ||
3433                    test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3434                        s->syncing = 1;
3435                else
3436                        s->replacing = 1;
3437        }
3438        rcu_read_unlock();
3439}
3440
3441static void handle_stripe(struct stripe_head *sh)
3442{
3443        struct stripe_head_state s;
3444        struct r5conf *conf = sh->raid_conf;
3445        int i;
3446        int prexor;
3447        int disks = sh->disks;
3448        struct r5dev *pdev, *qdev;
3449
3450        clear_bit(STRIPE_HANDLE, &sh->state);
3451        if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3452                /* already being handled, ensure it gets handled
3453                 * again when current action finishes */
3454                set_bit(STRIPE_HANDLE, &sh->state);
3455                return;
3456        }
3457
3458        if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3459                spin_lock(&sh->stripe_lock);
3460                /* Cannot process 'sync' concurrently with 'discard' */
3461                if (!test_bit(STRIPE_DISCARD, &sh->state) &&
3462                    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3463                        set_bit(STRIPE_SYNCING, &sh->state);
3464                        clear_bit(STRIPE_INSYNC, &sh->state);
3465                        clear_bit(STRIPE_REPLACED, &sh->state);
3466                }
3467                spin_unlock(&sh->stripe_lock);
3468        }
3469        clear_bit(STRIPE_DELAYED, &sh->state);
3470
3471        pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3472                "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3473               (unsigned long long)sh->sector, sh->state,
3474               atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3475               sh->check_state, sh->reconstruct_state);
3476
3477        analyse_stripe(sh, &s);
3478
3479        if (s.handle_bad_blocks) {
3480                set_bit(STRIPE_HANDLE, &sh->state);
3481                goto finish;
3482        }
3483
3484        if (unlikely(s.blocked_rdev)) {
3485                if (s.syncing || s.expanding || s.expanded ||
3486                    s.replacing || s.to_write || s.written) {
3487                        set_bit(STRIPE_HANDLE, &sh->state);
3488                        goto finish;
3489                }
3490                /* There is nothing for the blocked_rdev to block */
3491                rdev_dec_pending(s.blocked_rdev, conf->mddev);
3492                s.blocked_rdev = NULL;
3493        }
3494
3495        if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3496                set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3497                set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3498        }
3499
3500        pr_debug("locked=%d uptodate=%d to_read=%d"
3501               " to_write=%d failed=%d failed_num=%d,%d\n",
3502               s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3503               s.failed_num[0], s.failed_num[1]);
3504        /* check if the array has lost more than max_degraded devices and,
3505         * if so, some requests might need to be failed.
3506         */
3507        if (s.failed > conf->max_degraded) {
3508                sh->check_state = 0;
3509                sh->reconstruct_state = 0;
3510                if (s.to_read+s.to_write+s.written)
3511                        handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3512                if (s.syncing + s.replacing)
3513                        handle_failed_sync(conf, sh, &s);
3514        }
3515
3516        /* Now we check to see if any write operations have recently
3517         * completed
3518         */
3519        prexor = 0;
3520        if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3521                prexor = 1;
3522        if (sh->reconstruct_state == reconstruct_state_drain_result ||
3523            sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3524                sh->reconstruct_state = reconstruct_state_idle;
3525
3526                /* All the 'written' buffers and the parity block are ready to
3527                 * be written back to disk
3528                 */
3529                BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3530                       !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3531                BUG_ON(sh->qd_idx >= 0 &&
3532                       !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3533                       !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3534                for (i = disks; i--; ) {
3535                        struct r5dev *dev = &sh->dev[i];
3536                        if (test_bit(R5_LOCKED, &dev->flags) &&
3537                                (i == sh->pd_idx || i == sh->qd_idx ||
3538                                 dev->written)) {
3539                                pr_debug("Writing block %d\n", i);
3540                                set_bit(R5_Wantwrite, &dev->flags);
3541                                if (prexor)
3542                                        continue;
3543                                if (!test_bit(R5_Insync, &dev->flags) ||
3544                                    ((i == sh->pd_idx || i == sh->qd_idx)  &&
3545                                     s.failed == 0))
3546                                        set_bit(STRIPE_INSYNC, &sh->state);
3547                        }
3548                }
3549                if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3550                        s.dec_preread_active = 1;
3551        }
3552
3553        /*
3554         * might be able to return some write requests if the parity blocks
3555         * are safe, or on a failed drive
3556         */
3557        pdev = &sh->dev[sh->pd_idx];
3558        s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3559                || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3560        qdev = &sh->dev[sh->qd_idx];
3561        s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3562                || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3563                || conf->level < 6;
3564
3565        if (s.written &&
3566            (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3567                             && !test_bit(R5_LOCKED, &pdev->flags)
3568                             && (test_bit(R5_UPTODATE, &pdev->flags) ||
3569                                 test_bit(R5_Discard, &pdev->flags))))) &&
3570            (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3571                             && !test_bit(R5_LOCKED, &qdev->flags)
3572                             && (test_bit(R5_UPTODATE, &qdev->flags) ||
3573                                 test_bit(R5_Discard, &qdev->flags))))))
3574                handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3575
3576        /* Now we might consider reading some blocks, either to check/generate
3577         * parity, or to satisfy requests
3578         * or to load a block that is being partially written.
3579         */
3580        if (s.to_read || s.non_overwrite
3581            || (conf->level == 6 && s.to_write && s.failed)
3582            || (s.syncing && (s.uptodate + s.compute < disks))
3583            || s.replacing
3584            || s.expanding)
3585                handle_stripe_fill(sh, &s, disks);
3586
3587        /* Now to consider new write requests and what else, if anything
3588         * should be read.  We do not handle new writes when:
3589         * 1/ A 'write' operation (copy+xor) is already in flight.
3590         * 2/ A 'check' operation is in flight, as it may clobber the parity
3591         *    block.
3592         */
3593        if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3594                handle_stripe_dirtying(conf, sh, &s, disks);
3595
3596        /* maybe we need to check and possibly fix the parity for this stripe
3597         * Any reads will already have been scheduled, so we just see if enough
3598         * data is available.  The parity check is held off while parity
3599         * dependent operations are in flight.
3600         */
3601        if (sh->check_state ||
3602            (s.syncing && s.locked == 0 &&
3603             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3604             !test_bit(STRIPE_INSYNC, &sh->state))) {
3605                if (conf->level == 6)
3606                        handle_parity_checks6(conf, sh, &s, disks);
3607                else
3608                        handle_parity_checks5(conf, sh, &s, disks);
3609        }
3610
3611        if ((s.replacing || s.syncing) && s.locked == 0
3612            && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
3613            && !test_bit(STRIPE_REPLACED, &sh->state)) {
3614                /* Write out to replacement devices where possible */
3615                for (i = 0; i < conf->raid_disks; i++)
3616                        if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3617                                WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
3618                                set_bit(R5_WantReplace, &sh->dev[i].flags);
3619                                set_bit(R5_LOCKED, &sh->dev[i].flags);
3620                                s.locked++;
3621                        }
3622                if (s.replacing)
3623                        set_bit(STRIPE_INSYNC, &sh->state);
3624                set_bit(STRIPE_REPLACED, &sh->state);
3625        }
3626        if ((s.syncing || s.replacing) && s.locked == 0 &&
3627            !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3628            test_bit(STRIPE_INSYNC, &sh->state)) {
3629                md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3630                clear_bit(STRIPE_SYNCING, &sh->state);
3631                if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3632                        wake_up(&conf->wait_for_overlap);
3633        }
3634
3635        /* If the failed drives are just a ReadError, then we might need
3636         * to progress the repair/check process
3637         */
3638        if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3639                for (i = 0; i < s.failed; i++) {
3640                        struct r5dev *dev = &sh->dev[s.failed_num[i]];
3641                        if (test_bit(R5_ReadError, &dev->flags)
3642                            && !test_bit(R5_LOCKED, &dev->flags)
3643                            && test_bit(R5_UPTODATE, &dev->flags)
3644                                ) {
3645                                if (!test_bit(R5_ReWrite, &dev->flags)) {
3646                                        set_bit(R5_Wantwrite, &dev->flags);
3647                                        set_bit(R5_ReWrite, &dev->flags);
3648                                        set_bit(R5_LOCKED, &dev->flags);
3649                                        s.locked++;
3650                                } else {
3651                                        /* let's read it back */
3652                                        set_bit(R5_Wantread, &dev->flags);
3653                                        set_bit(R5_LOCKED, &dev->flags);
3654                                        s.locked++;
3655                                }
3656                        }
3657                }
3658
3659
3660        /* Finish reconstruct operations initiated by the expansion process */
3661        if (sh->reconstruct_state == reconstruct_state_result) {
3662                struct stripe_head *sh_src
3663                        = get_active_stripe(conf, sh->sector, 1, 1, 1);
3664                if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3665                        /* sh cannot be written until sh_src has been read.
3666                         * so arrange for sh to be delayed a little
3667                         */
3668                        set_bit(STRIPE_DELAYED, &sh->state);
3669                        set_bit(STRIPE_HANDLE, &sh->state);
3670                        if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3671                                              &sh_src->state))
3672                                atomic_inc(&conf->preread_active_stripes);
3673                        release_stripe(sh_src);
3674                        goto finish;
3675                }
3676                if (sh_src)
3677                        release_stripe(sh_src);
3678
3679                sh->reconstruct_state = reconstruct_state_idle;
3680                clear_bit(STRIPE_EXPANDING, &sh->state);
3681                for (i = conf->raid_disks; i--; ) {
3682                        set_bit(R5_Wantwrite, &sh->dev[i].flags);
3683                        set_bit(R5_LOCKED, &sh->dev[i].flags);
3684                        s.locked++;
3685                }
3686        }
3687
3688        if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3689            !sh->reconstruct_state) {
3690                /* Need to write out all blocks after computing parity */
3691                sh->disks = conf->raid_disks;
3692                stripe_set_idx(sh->sector, conf, 0, sh);
3693                schedule_reconstruction(sh, &s, 1, 1);
3694        } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3695                clear_bit(STRIPE_EXPAND_READY, &sh->state);
3696                atomic_dec(&conf->reshape_stripes);
3697                wake_up(&conf->wait_for_overlap);
3698                md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3699        }
3700
3701        if (s.expanding && s.locked == 0 &&
3702            !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3703                handle_stripe_expansion(conf, sh);
3704
3705finish:
3706        /* wait for this device to become unblocked */
3707        if (unlikely(s.blocked_rdev)) {
3708                if (conf->mddev->external)
3709                        md_wait_for_blocked_rdev(s.blocked_rdev,
3710                                                 conf->mddev);
3711                else
3712                        /* Internal metadata will immediately
3713                         * be written by raid5d, so we don't
3714                         * need to wait here.
3715                         */
3716                        rdev_dec_pending(s.blocked_rdev,
3717                                         conf->mddev);
3718        }
3719
3720        if (s.handle_bad_blocks)
3721                for (i = disks; i--; ) {
3722                        struct md_rdev *rdev;
3723                        struct r5dev *dev = &sh->dev[i];
3724                        if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3725                                /* We own a safe reference to the rdev */
3726                                rdev = conf->disks[i].rdev;
3727                                if (!rdev_set_badblocks(rdev, sh->sector,
3728                                                        STRIPE_SECTORS, 0))
3729                                        md_error(conf->mddev, rdev);
3730                                rdev_dec_pending(rdev, conf->mddev);
3731                        }
3732                        if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3733                                rdev = conf->disks[i].rdev;
3734                                rdev_clear_badblocks(rdev, sh->sector,
3735                                                     STRIPE_SECTORS, 0);
3736                                rdev_dec_pending(rdev, conf->mddev);
3737                        }
3738                        if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
3739                                rdev = conf->disks[i].replacement;
3740                                if (!rdev)
3741                                        /* rdev have been moved down */
3742                                        rdev = conf->disks[i].rdev;
3743                                rdev_clear_badblocks(rdev, sh->sector,
3744                                                     STRIPE_SECTORS, 0);
3745                                rdev_dec_pending(rdev, conf->mddev);
3746                        }
3747                }
3748
3749        if (s.ops_request)
3750                raid_run_ops(sh, s.ops_request);
3751
3752        ops_run_io(sh, &s);
3753
3754        if (s.dec_preread_active) {
3755                /* We delay this until after ops_run_io so that if make_request
3756                 * is waiting on a flush, it won't continue until the writes
3757                 * have actually been submitted.
3758                 */
3759                atomic_dec(&conf->preread_active_stripes);
3760                if (atomic_read(&conf->preread_active_stripes) <
3761                    IO_THRESHOLD)
3762                        md_wakeup_thread(conf->mddev->thread);
3763        }
3764
3765        return_io(s.return_bi);
3766
3767        clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
3768}
3769
3770static void raid5_activate_delayed(struct r5conf *conf)
3771{
3772        if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3773                while (!list_empty(&conf->delayed_list)) {
3774                        struct list_head *l = conf->delayed_list.next;
3775                        struct stripe_head *sh;
3776                        sh = list_entry(l, struct stripe_head, lru);
3777                        list_del_init(l);
3778                        clear_bit(STRIPE_DELAYED, &sh->state);
3779                        if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3780                                atomic_inc(&conf->preread_active_stripes);
3781                        list_add_tail(&sh->lru, &conf->hold_list);
3782                }
3783        }
3784}
3785
3786static void activate_bit_delay(struct r5conf *conf)
3787{
3788        /* device_lock is held */
3789        struct list_head head;
3790        list_add(&head, &conf->bitmap_list);
3791        list_del_init(&conf->bitmap_list);
3792        while (!list_empty(&head)) {
3793                struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3794                list_del_init(&sh->lru);
3795                atomic_inc(&sh->count);
3796                __release_stripe(conf, sh);
3797        }
3798}
3799
3800int md_raid5_congested(struct mddev *mddev, int bits)
3801{
3802        struct r5conf *conf = mddev->private;
3803
3804        /* No difference between reads and writes.  Just check
3805         * how busy the stripe_cache is
3806         */
3807
3808        if (conf->inactive_blocked)
3809                return 1;
3810        if (conf->quiesce)
3811                return 1;
3812        if (list_empty_careful(&conf->inactive_list))
3813                return 1;
3814
3815        return 0;
3816}
3817EXPORT_SYMBOL_GPL(md_raid5_congested);
3818
3819static int raid5_congested(void *data, int bits)
3820{
3821        struct mddev *mddev = data;
3822
3823        return mddev_congested(mddev, bits) ||
3824                md_raid5_congested(mddev, bits);
3825}
3826
3827/* We want read requests to align with chunks where possible,
3828 * but write requests don't need to.
3829 */
3830static int raid5_mergeable_bvec(struct request_queue *q,
3831                                struct bvec_merge_data *bvm,
3832                                struct bio_vec *biovec)
3833{
3834        struct mddev *mddev = q->queuedata;
3835        sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3836        int max;
3837        unsigned int chunk_sectors = mddev->chunk_sectors;
3838        unsigned int bio_sectors = bvm->bi_size >> 9;
3839
3840        if ((bvm->bi_rw & 1) == WRITE)
3841                return biovec->bv_len; /* always allow writes to be mergeable */
3842
3843        if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3844                chunk_sectors = mddev->new_chunk_sectors;
3845        max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3846        if (max < 0) max = 0;
3847        if (max <= biovec->bv_len && bio_sectors == 0)
3848                return biovec->bv_len;
3849        else
3850                return max;
3851}
3852
3853
3854static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
3855{
3856        sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3857        unsigned int chunk_sectors = mddev->chunk_sectors;
3858        unsigned int bio_sectors = bio_sectors(bio);
3859
3860        if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3861                chunk_sectors = mddev->new_chunk_sectors;
3862        return  chunk_sectors >=
3863                ((sector & (chunk_sectors - 1)) + bio_sectors);
3864}
3865
3866/*
3867 *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3868 *  later sampled by raid5d.
3869 */
3870static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
3871{
3872        unsigned long flags;
3873
3874        spin_lock_irqsave(&conf->device_lock, flags);
3875
3876        bi->bi_next = conf->retry_read_aligned_list;
3877        conf->retry_read_aligned_list = bi;
3878
3879        spin_unlock_irqrestore(&conf->device_lock, flags);
3880        md_wakeup_thread(conf->mddev->thread);
3881}
3882
3883
3884static struct bio *remove_bio_from_retry(struct r5conf *conf)
3885{
3886        struct bio *bi;
3887
3888        bi = conf->retry_read_aligned;
3889        if (bi) {
3890                conf->retry_read_aligned = NULL;
3891                return bi;
3892        }
3893        bi = conf->retry_read_aligned_list;
3894        if(bi) {
3895                conf->retry_read_aligned_list = bi->bi_next;
3896                bi->bi_next = NULL;
3897                /*
3898                 * this sets the active strip count to 1 and the processed
3899                 * strip count to zero (upper 8 bits)
3900                 */
3901                raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
3902        }
3903
3904        return bi;
3905}
3906
3907
3908/*
3909 *  The "raid5_align_endio" should check if the read succeeded and if it
3910 *  did, call bio_endio on the original bio (having bio_put the new bio
3911 *  first).
3912 *  If the read failed..
3913 */
3914static void raid5_align_endio(struct bio *bi, int error)
3915{
3916        struct bio* raid_bi  = bi->bi_private;
3917        struct mddev *mddev;
3918        struct r5conf *conf;
3919        int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3920        struct md_rdev *rdev;
3921
3922        bio_put(bi);
3923
3924        rdev = (void*)raid_bi->bi_next;
3925        raid_bi->bi_next = NULL;
3926        mddev = rdev->mddev;
3927        conf = mddev->private;
3928
3929        rdev_dec_pending(rdev, conf->mddev);
3930
3931        if (!error && uptodate) {
3932                trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
3933                                         raid_bi, 0);
3934                bio_endio(raid_bi, 0);
3935                if (atomic_dec_and_test(&conf->active_aligned_reads))
3936                        wake_up(&conf->wait_for_stripe);
3937                return;
3938        }
3939
3940
3941        pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3942
3943        add_bio_to_retry(raid_bi, conf);
3944}
3945
3946static int bio_fits_rdev(struct bio *bi)
3947{
3948        struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3949
3950        if (bio_sectors(bi) > queue_max_sectors(q))
3951                return 0;
3952        blk_recount_segments(q, bi);
3953        if (bi->bi_phys_segments > queue_max_segments(q))
3954                return 0;
3955
3956        if (q->merge_bvec_fn)
3957                /* it's too hard to apply the merge_bvec_fn at this stage,
3958                 * just just give up
3959                 */
3960                return 0;
3961
3962        return 1;
3963}
3964
3965
3966static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
3967{
3968        struct r5conf *conf = mddev->private;
3969        int dd_idx;
3970        struct bio* align_bi;
3971        struct md_rdev *rdev;
3972        sector_t end_sector;
3973
3974        if (!in_chunk_boundary(mddev, raid_bio)) {
3975                pr_debug("chunk_aligned_read : non aligned\n");
3976                return 0;
3977        }
3978        /*
3979         * use bio_clone_mddev to make a copy of the bio
3980         */
3981        align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
3982        if (!align_bi)
3983                return 0;
3984        /*
3985         *   set bi_end_io to a new function, and set bi_private to the
3986         *     original bio.
3987         */
3988        align_bi->bi_end_io  = raid5_align_endio;
3989        align_bi->bi_private = raid_bio;
3990        /*
3991         *      compute position
3992         */
3993        align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
3994                                                    0,
3995                                                    &dd_idx, NULL);
3996
3997        end_sector = bio_end_sector(align_bi);
3998        rcu_read_lock();
3999        rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4000        if (!rdev || test_bit(Faulty, &rdev->flags) ||
4001            rdev->recovery_offset < end_sector) {
4002                rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4003                if (rdev &&
4004                    (test_bit(Faulty, &rdev->flags) ||
4005                    !(test_bit(In_sync, &rdev->flags) ||
4006                      rdev->recovery_offset >= end_sector)))
4007                        rdev = NULL;
4008        }
4009        if (rdev) {
4010                sector_t first_bad;
4011                int bad_sectors;
4012
4013                atomic_inc(&rdev->nr_pending);
4014                rcu_read_unlock();
4015                raid_bio->bi_next = (void*)rdev;
4016                align_bi->bi_bdev =  rdev->bdev;
4017                align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
4018
4019                if (!bio_fits_rdev(align_bi) ||
4020                    is_badblock(rdev, align_bi->bi_sector, bio_sectors(align_bi),
4021                                &first_bad, &bad_sectors)) {
4022                        /* too big in some way, or has a known bad block */
4023                        bio_put(align_bi);
4024                        rdev_dec_pending(rdev, mddev);
4025                        return 0;
4026                }
4027
4028                /* No reshape active, so we can trust rdev->data_offset */
4029                align_bi->bi_sector += rdev->data_offset;
4030
4031                spin_lock_irq(&conf->device_lock);
4032                wait_event_lock_irq(conf->wait_for_stripe,
4033                                    conf->quiesce == 0,
4034                                    conf->device_lock);
4035                atomic_inc(&conf->active_aligned_reads);
4036                spin_unlock_irq(&conf->device_lock);
4037
4038                if (mddev->gendisk)
4039                        trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4040                                              align_bi, disk_devt(mddev->gendisk),
4041                                              raid_bio->bi_sector);
4042                generic_make_request(align_bi);
4043                return 1;
4044        } else {
4045                rcu_read_unlock();
4046                bio_put(align_bi);
4047                return 0;
4048        }
4049}
4050
4051/* __get_priority_stripe - get the next stripe to process
4052 *
4053 * Full stripe writes are allowed to pass preread active stripes up until
4054 * the bypass_threshold is exceeded.  In general the bypass_count
4055 * increments when the handle_list is handled before the hold_list; however, it
4056 * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4057 * stripe with in flight i/o.  The bypass_count will be reset when the
4058 * head of the hold_list has changed, i.e. the head was promoted to the
4059 * handle_list.
4060 */
4061static struct stripe_head *__get_priority_stripe(struct r5conf *conf)
4062{
4063        struct stripe_head *sh;
4064
4065        pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4066                  __func__,
4067                  list_empty(&conf->handle_list) ? "empty" : "busy",
4068                  list_empty(&conf->hold_list) ? "empty" : "busy",
4069                  atomic_read(&conf->pending_full_writes), conf->bypass_count);
4070
4071        if (!list_empty(&conf->handle_list)) {
4072                sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
4073
4074                if (list_empty(&conf->hold_list))
4075                        conf->bypass_count = 0;
4076                else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4077                        if (conf->hold_list.next == conf->last_hold)
4078                                conf->bypass_count++;
4079                        else {
4080                                conf->last_hold = conf->hold_list.next;
4081                                conf->bypass_count -= conf->bypass_threshold;
4082                                if (conf->bypass_count < 0)
4083                                        conf->bypass_count = 0;
4084                        }
4085                }
4086        } else if (!list_empty(&conf->hold_list) &&
4087                   ((conf->bypass_threshold &&
4088                     conf->bypass_count > conf->bypass_threshold) ||
4089                    atomic_read(&conf->pending_full_writes) == 0)) {
4090                sh = list_entry(conf->hold_list.next,
4091                                typeof(*sh), lru);
4092                conf->bypass_count -= conf->bypass_threshold;
4093                if (conf->bypass_count < 0)
4094                        conf->bypass_count = 0;
4095        } else
4096                return NULL;
4097
4098        list_del_init(&sh->lru);
4099        atomic_inc(&sh->count);
4100        BUG_ON(atomic_read(&sh->count) != 1);
4101        return sh;
4102}
4103
4104struct raid5_plug_cb {
4105        struct blk_plug_cb      cb;
4106        struct list_head        list;
4107};
4108
4109static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4110{
4111        struct raid5_plug_cb *cb = container_of(
4112                blk_cb, struct raid5_plug_cb, cb);
4113        struct stripe_head *sh;
4114        struct mddev *mddev = cb->cb.data;
4115        struct r5conf *conf = mddev->private;
4116        int cnt = 0;
4117
4118        if (cb->list.next && !list_empty(&cb->list)) {
4119                spin_lock_irq(&conf->device_lock);
4120                while (!list_empty(&cb->list)) {
4121                        sh = list_first_entry(&cb->list, struct stripe_head, lru);
4122                        list_del_init(&sh->lru);
4123                        /*
4124                         * avoid race release_stripe_plug() sees
4125                         * STRIPE_ON_UNPLUG_LIST clear but the stripe
4126                         * is still in our list
4127                         */
4128                        smp_mb__before_clear_bit();
4129                        clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4130                        __release_stripe(conf, sh);
4131                        cnt++;
4132                }
4133                spin_unlock_irq(&conf->device_lock);
4134        }
4135        if (mddev->queue)
4136                trace_block_unplug(mddev->queue, cnt, !from_schedule);
4137        kfree(cb);
4138}
4139
4140static void release_stripe_plug(struct mddev *mddev,
4141                                struct stripe_head *sh)
4142{
4143        struct blk_plug_cb *blk_cb = blk_check_plugged(
4144                raid5_unplug, mddev,
4145                sizeof(struct raid5_plug_cb));
4146        struct raid5_plug_cb *cb;
4147
4148        if (!blk_cb) {
4149                release_stripe(sh);
4150                return;
4151        }
4152
4153        cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4154
4155        if (cb->list.next == NULL)
4156                INIT_LIST_HEAD(&cb->list);
4157
4158        if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4159                list_add_tail(&sh->lru, &cb->list);
4160        else
4161                release_stripe(sh);
4162}
4163
4164static void make_discard_request(struct mddev *mddev, struct bio *bi)
4165{
4166        struct r5conf *conf = mddev->private;
4167        sector_t logical_sector, last_sector;
4168        struct stripe_head *sh;
4169        int remaining;
4170        int stripe_sectors;
4171
4172        if (mddev->reshape_position != MaxSector)
4173                /* Skip discard while reshape is happening */
4174                return;
4175
4176        logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4177        last_sector = bi->bi_sector + (bi->bi_size>>9);
4178
4179        bi->bi_next = NULL;
4180        bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4181
4182        stripe_sectors = conf->chunk_sectors *
4183                (conf->raid_disks - conf->max_degraded);
4184        logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4185                                               stripe_sectors);
4186        sector_div(last_sector, stripe_sectors);
4187
4188        logical_sector *= conf->chunk_sectors;
4189        last_sector *= conf->chunk_sectors;
4190
4191        for (; logical_sector < last_sector;
4192             logical_sector += STRIPE_SECTORS) {
4193                DEFINE_WAIT(w);
4194                int d;
4195        again:
4196                sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4197                prepare_to_wait(&conf->wait_for_overlap, &w,
4198                                TASK_UNINTERRUPTIBLE);
4199                set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4200                if (test_bit(STRIPE_SYNCING, &sh->state)) {
4201                        release_stripe(sh);
4202                        schedule();
4203                        goto again;
4204                }
4205                clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4206                spin_lock_irq(&sh->stripe_lock);
4207                for (d = 0; d < conf->raid_disks; d++) {
4208                        if (d == sh->pd_idx || d == sh->qd_idx)
4209                                continue;
4210                        if (sh->dev[d].towrite || sh->dev[d].toread) {
4211                                set_bit(R5_Overlap, &sh->dev[d].flags);
4212                                spin_unlock_irq(&sh->stripe_lock);
4213                                release_stripe(sh);
4214                                schedule();
4215                                goto again;
4216                        }
4217                }
4218                set_bit(STRIPE_DISCARD, &sh->state);
4219                finish_wait(&conf->wait_for_overlap, &w);
4220                for (d = 0; d < conf->raid_disks; d++) {
4221                        if (d == sh->pd_idx || d == sh->qd_idx)
4222                                continue;
4223                        sh->dev[d].towrite = bi;
4224                        set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4225                        raid5_inc_bi_active_stripes(bi);
4226                }
4227                spin_unlock_irq(&sh->stripe_lock);
4228                if (conf->mddev->bitmap) {
4229                        for (d = 0;
4230                             d < conf->raid_disks - conf->max_degraded;
4231                             d++)
4232                                bitmap_startwrite(mddev->bitmap,
4233                                                  sh->sector,
4234                                                  STRIPE_SECTORS,
4235                                                  0);
4236                        sh->bm_seq = conf->seq_flush + 1;
4237                        set_bit(STRIPE_BIT_DELAY, &sh->state);
4238                }
4239
4240                set_bit(STRIPE_HANDLE, &sh->state);
4241                clear_bit(STRIPE_DELAYED, &sh->state);
4242                if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4243                        atomic_inc(&conf->preread_active_stripes);
4244                release_stripe_plug(mddev, sh);
4245        }
4246
4247        remaining = raid5_dec_bi_active_stripes(bi);
4248        if (remaining == 0) {
4249                md_write_end(mddev);
4250                bio_endio(bi, 0);
4251        }
4252}
4253
4254static void make_request(struct mddev *mddev, struct bio * bi)
4255{
4256        struct r5conf *conf = mddev->private;
4257        int dd_idx;
4258        sector_t new_sector;
4259        sector_t logical_sector, last_sector;
4260        struct stripe_head *sh;
4261        const int rw = bio_data_dir(bi);
4262        int remaining;
4263
4264        if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4265                md_flush_request(mddev, bi);
4266                return;
4267        }
4268
4269        md_write_start(mddev, bi);
4270
4271        if (rw == READ &&
4272             mddev->reshape_position == MaxSector &&
4273             chunk_aligned_read(mddev,bi))
4274                return;
4275
4276        if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4277                make_discard_request(mddev, bi);
4278                return;
4279        }
4280
4281        logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4282        last_sector = bio_end_sector(bi);
4283        bi->bi_next = NULL;
4284        bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
4285
4286        for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4287                DEFINE_WAIT(w);
4288                int previous;
4289
4290        retry:
4291                previous = 0;
4292                prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4293                if (unlikely(conf->reshape_progress != MaxSector)) {
4294                        /* spinlock is needed as reshape_progress may be
4295                         * 64bit on a 32bit platform, and so it might be
4296                         * possible to see a half-updated value
4297                         * Of course reshape_progress could change after
4298                         * the lock is dropped, so once we get a reference
4299                         * to the stripe that we think it is, we will have
4300                         * to check again.
4301                         */
4302                        spin_lock_irq(&conf->device_lock);
4303                        if (mddev->reshape_backwards
4304                            ? logical_sector < conf->reshape_progress
4305                            : logical_sector >= conf->reshape_progress) {
4306                                previous = 1;
4307                        } else {
4308                                if (mddev->reshape_backwards
4309                                    ? logical_sector < conf->reshape_safe
4310                                    : logical_sector >= conf->reshape_safe) {
4311                                        spin_unlock_irq(&conf->device_lock);
4312                                        schedule();
4313                                        goto retry;
4314                                }
4315                        }
4316                        spin_unlock_irq(&conf->device_lock);
4317                }
4318
4319                new_sector = raid5_compute_sector(conf, logical_sector,
4320                                                  previous,
4321                                                  &dd_idx, NULL);
4322                pr_debug("raid456: make_request, sector %llu logical %llu\n",
4323                        (unsigned long long)new_sector, 
4324                        (unsigned long long)logical_sector);
4325
4326                sh = get_active_stripe(conf, new_sector, previous,
4327                                       (bi->bi_rw&RWA_MASK), 0);
4328                if (sh) {
4329                        if (unlikely(previous)) {
4330                                /* expansion might have moved on while waiting for a
4331                                 * stripe, so we must do the range check again.
4332                                 * Expansion could still move past after this
4333                                 * test, but as we are holding a reference to
4334                                 * 'sh', we know that if that happens,
4335                                 *  STRIPE_EXPANDING will get set and the expansion
4336                                 * won't proceed until we finish with the stripe.
4337                                 */
4338                                int must_retry = 0;
4339                                spin_lock_irq(&conf->device_lock);
4340                                if (mddev->reshape_backwards
4341                                    ? logical_sector >= conf->reshape_progress
4342                                    : logical_sector < conf->reshape_progress)
4343                                        /* mismatch, need to try again */
4344                                        must_retry = 1;
4345                                spin_unlock_irq(&conf->device_lock);
4346                                if (must_retry) {
4347                                        release_stripe(sh);
4348                                        schedule();
4349                                        goto retry;
4350                                }
4351                        }
4352
4353                        if (rw == WRITE &&
4354                            logical_sector >= mddev->suspend_lo &&
4355                            logical_sector < mddev->suspend_hi) {
4356                                release_stripe(sh);
4357                                /* As the suspend_* range is controlled by
4358                                 * userspace, we want an interruptible
4359                                 * wait.
4360                                 */
4361                                flush_signals(current);
4362                                prepare_to_wait(&conf->wait_for_overlap,
4363                                                &w, TASK_INTERRUPTIBLE);
4364                                if (logical_sector >= mddev->suspend_lo &&
4365                                    logical_sector < mddev->suspend_hi)
4366                                        schedule();
4367                                goto retry;
4368                        }
4369
4370                        if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4371                            !add_stripe_bio(sh, bi, dd_idx, rw)) {
4372                                /* Stripe is busy expanding or
4373                                 * add failed due to overlap.  Flush everything
4374                                 * and wait a while
4375                                 */
4376                                md_wakeup_thread(mddev->thread);
4377                                release_stripe(sh);
4378                                schedule();
4379                                goto retry;
4380                        }
4381                        finish_wait(&conf->wait_for_overlap, &w);
4382                        set_bit(STRIPE_HANDLE, &sh->state);
4383                        clear_bit(STRIPE_DELAYED, &sh->state);
4384                        if ((bi->bi_rw & REQ_SYNC) &&
4385                            !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4386                                atomic_inc(&conf->preread_active_stripes);
4387                        release_stripe_plug(mddev, sh);
4388                } else {
4389                        /* cannot get stripe for read-ahead, just give-up */
4390                        clear_bit(BIO_UPTODATE, &bi->bi_flags);
4391                        finish_wait(&conf->wait_for_overlap, &w);
4392                        break;
4393                }
4394        }
4395
4396        remaining = raid5_dec_bi_active_stripes(bi);
4397        if (remaining == 0) {
4398
4399                if ( rw == WRITE )
4400                        md_write_end(mddev);
4401
4402                trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4403                                         bi, 0);
4404                bio_endio(bi, 0);
4405        }
4406}
4407
4408static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4409
4410static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4411{
4412        /* reshaping is quite different to recovery/resync so it is
4413         * handled quite separately ... here.
4414         *
4415         * On each call to sync_request, we gather one chunk worth of
4416         * destination stripes and flag them as expanding.
4417         * Then we find all the source stripes and request reads.
4418         * As the reads complete, handle_stripe will copy the data
4419         * into the destination stripe and release that stripe.
4420         */
4421        struct r5conf *conf = mddev->private;
4422        struct stripe_head *sh;
4423        sector_t first_sector, last_sector;
4424        int raid_disks = conf->previous_raid_disks;
4425        int data_disks = raid_disks - conf->max_degraded;
4426        int new_data_disks = conf->raid_disks - conf->max_degraded;
4427        int i;
4428        int dd_idx;
4429        sector_t writepos, readpos, safepos;
4430        sector_t stripe_addr;
4431        int reshape_sectors;
4432        struct list_head stripes;
4433
4434        if (sector_nr == 0) {
4435                /* If restarting in the middle, skip the initial sectors */
4436                if (mddev->reshape_backwards &&
4437                    conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4438                        sector_nr = raid5_size(mddev, 0, 0)
4439                                - conf->reshape_progress;
4440                } else if (!mddev->reshape_backwards &&
4441                           conf->reshape_progress > 0)
4442                        sector_nr = conf->reshape_progress;
4443                sector_div(sector_nr, new_data_disks);
4444                if (sector_nr) {
4445                        mddev->curr_resync_completed = sector_nr;
4446                        sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4447                        *skipped = 1;
4448                        return sector_nr;
4449                }
4450        }
4451
4452        /* We need to process a full chunk at a time.
4453         * If old and new chunk sizes differ, we need to process the
4454         * largest of these
4455         */
4456        if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4457                reshape_sectors = mddev->new_chunk_sectors;
4458        else
4459                reshape_sectors = mddev->chunk_sectors;
4460
4461        /* We update the metadata at least every 10 seconds, or when
4462         * the data about to be copied would over-write the source of
4463         * the data at the front of the range.  i.e. one new_stripe
4464         * along from reshape_progress new_maps to after where
4465         * reshape_safe old_maps to
4466         */
4467        writepos = conf->reshape_progress;
4468        sector_div(writepos, new_data_disks);
4469        readpos = conf->reshape_progress;
4470        sector_div(readpos, data_disks);
4471        safepos = conf->reshape_safe;
4472        sector_div(safepos, data_disks);
4473        if (mddev->reshape_backwards) {
4474                writepos -= min_t(sector_t, reshape_sectors, writepos);
4475                readpos += reshape_sectors;
4476                safepos += reshape_sectors;
4477        } else {
4478                writepos += reshape_sectors;
4479                readpos -= min_t(sector_t, reshape_sectors, readpos);
4480                safepos -= min_t(sector_t, reshape_sectors, safepos);
4481        }
4482
4483        /* Having calculated the 'writepos' possibly use it
4484         * to set 'stripe_addr' which is where we will write to.
4485         */
4486        if (mddev->reshape_backwards) {
4487                BUG_ON(conf->reshape_progress == 0);
4488                stripe_addr = writepos;
4489                BUG_ON((mddev->dev_sectors &
4490                        ~((sector_t)reshape_sectors - 1))
4491                       - reshape_sectors - stripe_addr
4492                       != sector_nr);
4493        } else {
4494                BUG_ON(writepos != sector_nr + reshape_sectors);
4495                stripe_addr = sector_nr;
4496        }
4497
4498        /* 'writepos' is the most advanced device address we might write.
4499         * 'readpos' is the least advanced device address we might read.
4500         * 'safepos' is the least address recorded in the metadata as having
4501         *     been reshaped.
4502         * If there is a min_offset_diff, these are adjusted either by
4503         * increasing the safepos/readpos if diff is negative, or
4504         * increasing writepos if diff is positive.
4505         * If 'readpos' is then behind 'writepos', there is no way that we can
4506         * ensure safety in the face of a crash - that must be done by userspace
4507         * making a backup of the data.  So in that case there is no particular
4508         * rush to update metadata.
4509         * Otherwise if 'safepos' is behind 'writepos', then we really need to
4510         * update the metadata to advance 'safepos' to match 'readpos' so that
4511         * we can be safe in the event of a crash.
4512         * So we insist on updating metadata if safepos is behind writepos and
4513         * readpos is beyond writepos.
4514         * In any case, update the metadata every 10 seconds.
4515         * Maybe that number should be configurable, but I'm not sure it is
4516         * worth it.... maybe it could be a multiple of safemode_delay???
4517         */
4518        if (conf->min_offset_diff < 0) {
4519                safepos += -conf->min_offset_diff;
4520                readpos += -conf->min_offset_diff;
4521        } else
4522                writepos += conf->min_offset_diff;
4523
4524        if ((mddev->reshape_backwards
4525             ? (safepos > writepos && readpos < writepos)
4526             : (safepos < writepos && readpos > writepos)) ||
4527            time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4528                /* Cannot proceed until we've updated the superblock... */
4529                wait_event(conf->wait_for_overlap,
4530                           atomic_read(&conf->reshape_stripes)==0);
4531                mddev->reshape_position = conf->reshape_progress;
4532                mddev->curr_resync_completed = sector_nr;
4533                conf->reshape_checkpoint = jiffies;
4534                set_bit(MD_CHANGE_DEVS, &mddev->flags);
4535                md_wakeup_thread(mddev->thread);
4536                wait_event(mddev->sb_wait, mddev->flags == 0 ||
4537                           kthread_should_stop());
4538                spin_lock_irq(&conf->device_lock);
4539                conf->reshape_safe = mddev->reshape_position;
4540                spin_unlock_irq(&conf->device_lock);
4541                wake_up(&conf->wait_for_overlap);
4542                sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4543        }
4544
4545        INIT_LIST_HEAD(&stripes);
4546        for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4547                int j;
4548                int skipped_disk = 0;
4549                sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4550                set_bit(STRIPE_EXPANDING, &sh->state);
4551                atomic_inc(&conf->reshape_stripes);
4552                /* If any of this stripe is beyond the end of the old
4553                 * array, then we need to zero those blocks
4554                 */
4555                for (j=sh->disks; j--;) {
4556                        sector_t s;
4557                        if (j == sh->pd_idx)
4558                                continue;
4559                        if (conf->level == 6 &&
4560                            j == sh->qd_idx)
4561                                continue;
4562                        s = compute_blocknr(sh, j, 0);
4563                        if (s < raid5_size(mddev, 0, 0)) {
4564                                skipped_disk = 1;
4565                                continue;
4566                        }
4567                        memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4568                        set_bit(R5_Expanded, &sh->dev[j].flags);
4569                        set_bit(R5_UPTODATE, &sh->dev[j].flags);
4570                }
4571                if (!skipped_disk) {
4572                        set_bit(STRIPE_EXPAND_READY, &sh->state);
4573                        set_bit(STRIPE_HANDLE, &sh->state);
4574                }
4575                list_add(&sh->lru, &stripes);
4576        }
4577        spin_lock_irq(&conf->device_lock);
4578        if (mddev->reshape_backwards)
4579                conf->reshape_progress -= reshape_sectors * new_data_disks;
4580        else
4581                conf->reshape_progress += reshape_sectors * new_data_disks;
4582        spin_unlock_irq(&conf->device_lock);
4583        /* Ok, those stripe are ready. We can start scheduling
4584         * reads on the source stripes.
4585         * The source stripes are determined by mapping the first and last
4586         * block on the destination stripes.
4587         */
4588        first_sector =
4589                raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4590                                     1, &dd_idx, NULL);
4591        last_sector =
4592                raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4593                                            * new_data_disks - 1),
4594                                     1, &dd_idx, NULL);
4595        if (last_sector >= mddev->dev_sectors)
4596                last_sector = mddev->dev_sectors - 1;
4597        while (first_sector <= last_sector) {
4598                sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4599                set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4600                set_bit(STRIPE_HANDLE, &sh->state);
4601                release_stripe(sh);
4602                first_sector += STRIPE_SECTORS;
4603        }
4604        /* Now that the sources are clearly marked, we can release
4605         * the destination stripes
4606         */
4607        while (!list_empty(&stripes)) {
4608                sh = list_entry(stripes.next, struct stripe_head, lru);
4609                list_del_init(&sh->lru);
4610                release_stripe(sh);
4611        }
4612        /* If this takes us to the resync_max point where we have to pause,
4613         * then we need to write out the superblock.
4614         */
4615        sector_nr += reshape_sectors;
4616        if ((sector_nr - mddev->curr_resync_completed) * 2
4617            >= mddev->resync_max - mddev->curr_resync_completed) {
4618                /* Cannot proceed until we've updated the superblock... */
4619                wait_event(conf->wait_for_overlap,
4620                           atomic_read(&conf->reshape_stripes) == 0);
4621                mddev->reshape_position = conf->reshape_progress;
4622                mddev->curr_resync_completed = sector_nr;
4623                conf->reshape_checkpoint = jiffies;
4624                set_bit(MD_CHANGE_DEVS, &mddev->flags);
4625                md_wakeup_thread(mddev->thread);
4626                wait_event(mddev->sb_wait,
4627                           !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4628                           || kthread_should_stop());
4629                spin_lock_irq(&conf->device_lock);
4630                conf->reshape_safe = mddev->reshape_position;
4631                spin_unlock_irq(&conf->device_lock);
4632                wake_up(&conf->wait_for_overlap);
4633                sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4634        }
4635        return reshape_sectors;
4636}
4637
4638/* FIXME go_faster isn't used */
4639static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4640{
4641        struct r5conf *conf = mddev->private;
4642        struct stripe_head *sh;
4643        sector_t max_sector = mddev->dev_sectors;
4644        sector_t sync_blocks;
4645        int still_degraded = 0;
4646        int i;
4647
4648        if (sector_nr >= max_sector) {
4649                /* just being told to finish up .. nothing much to do */
4650
4651                if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4652                        end_reshape(conf);
4653                        return 0;
4654                }
4655
4656                if (mddev->curr_resync < max_sector) /* aborted */
4657                        bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4658                                        &sync_blocks, 1);
4659                else /* completed sync */
4660                        conf->fullsync = 0;
4661                bitmap_close_sync(mddev->bitmap);
4662
4663                return 0;
4664        }
4665
4666        /* Allow raid5_quiesce to complete */
4667        wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4668
4669        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4670                return reshape_request(mddev, sector_nr, skipped);
4671
4672        /* No need to check resync_max as we never do more than one
4673         * stripe, and as resync_max will always be on a chunk boundary,
4674         * if the check in md_do_sync didn't fire, there is no chance
4675         * of overstepping resync_max here
4676         */
4677
4678        /* if there is too many failed drives and we are trying
4679         * to resync, then assert that we are finished, because there is
4680         * nothing we can do.
4681         */
4682        if (mddev->degraded >= conf->max_degraded &&
4683            test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4684                sector_t rv = mddev->dev_sectors - sector_nr;
4685                *skipped = 1;
4686                return rv;
4687        }
4688        if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4689            !conf->fullsync &&
4690            !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4691            sync_blocks >= STRIPE_SECTORS) {
4692                /* we can skip this block, and probably more */
4693                sync_blocks /= STRIPE_SECTORS;
4694                *skipped = 1;
4695                return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4696        }
4697
4698        bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4699
4700        sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4701        if (sh == NULL) {
4702                sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4703                /* make sure we don't swamp the stripe cache if someone else
4704                 * is trying to get access
4705                 */
4706                schedule_timeout_uninterruptible(1);
4707        }
4708        /* Need to check if array will still be degraded after recovery/resync
4709         * We don't need to check the 'failed' flag as when that gets set,
4710         * recovery aborts.
4711         */
4712        for (i = 0; i < conf->raid_disks; i++)
4713                if (conf->disks[i].rdev == NULL)
4714                        still_degraded = 1;
4715
4716        bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4717
4718        set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4719
4720        handle_stripe(sh);
4721        release_stripe(sh);
4722
4723        return STRIPE_SECTORS;
4724}
4725
4726static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
4727{
4728        /* We may not be able to submit a whole bio at once as there
4729         * may not be enough stripe_heads available.
4730         * We cannot pre-allocate enough stripe_heads as we may need
4731         * more than exist in the cache (if we allow ever large chunks).
4732         * So we do one stripe head at a time and record in
4733         * ->bi_hw_segments how many have been done.
4734         *
4735         * We *know* that this entire raid_bio is in one chunk, so
4736         * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4737         */
4738        struct stripe_head *sh;
4739        int dd_idx;
4740        sector_t sector, logical_sector, last_sector;
4741        int scnt = 0;
4742        int remaining;
4743        int handled = 0;
4744
4745        logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4746        sector = raid5_compute_sector(conf, logical_sector,
4747                                      0, &dd_idx, NULL);
4748        last_sector = bio_end_sector(raid_bio);
4749
4750        for (; logical_sector < last_sector;
4751             logical_sector += STRIPE_SECTORS,
4752                     sector += STRIPE_SECTORS,
4753                     scnt++) {
4754
4755                if (scnt < raid5_bi_processed_stripes(raid_bio))
4756                        /* already done this stripe */
4757                        continue;
4758
4759                sh = get_active_stripe(conf, sector, 0, 1, 0);
4760
4761                if (!sh) {
4762                        /* failed to get a stripe - must wait */
4763                        raid5_set_bi_processed_stripes(raid_bio, scnt);
4764                        conf->retry_read_aligned = raid_bio;
4765                        return handled;
4766                }
4767
4768                if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4769                        release_stripe(sh);
4770                        raid5_set_bi_processed_stripes(raid_bio, scnt);
4771                        conf->retry_read_aligned = raid_bio;
4772                        return handled;
4773                }
4774
4775                set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
4776                handle_stripe(sh);
4777                release_stripe(sh);
4778                handled++;
4779        }
4780        remaining = raid5_dec_bi_active_stripes(raid_bio);
4781        if (remaining == 0) {
4782                trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
4783                                         raid_bio, 0);
4784                bio_endio(raid_bio, 0);
4785        }
4786        if (atomic_dec_and_test(&conf->active_aligned_reads))
4787                wake_up(&