linux/drivers/md/raid10.c
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   1/*
   2 * raid10.c : Multiple Devices driver for Linux
   3 *
   4 * Copyright (C) 2000-2004 Neil Brown
   5 *
   6 * RAID-10 support for md.
   7 *
   8 * Base on code in raid1.c.  See raid1.c for further copyright information.
   9 *
  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#include <linux/slab.h>
  22#include <linux/delay.h>
  23#include <linux/blkdev.h>
  24#include <linux/module.h>
  25#include <linux/seq_file.h>
  26#include <linux/ratelimit.h>
  27#include <linux/kthread.h>
  28#include "md.h"
  29#include "raid10.h"
  30#include "raid0.h"
  31#include "bitmap.h"
  32
  33/*
  34 * RAID10 provides a combination of RAID0 and RAID1 functionality.
  35 * The layout of data is defined by
  36 *    chunk_size
  37 *    raid_disks
  38 *    near_copies (stored in low byte of layout)
  39 *    far_copies (stored in second byte of layout)
  40 *    far_offset (stored in bit 16 of layout )
  41 *
  42 * The data to be stored is divided into chunks using chunksize.
  43 * Each device is divided into far_copies sections.
  44 * In each section, chunks are laid out in a style similar to raid0, but
  45 * near_copies copies of each chunk is stored (each on a different drive).
  46 * The starting device for each section is offset near_copies from the starting
  47 * device of the previous section.
  48 * Thus they are (near_copies*far_copies) of each chunk, and each is on a different
  49 * drive.
  50 * near_copies and far_copies must be at least one, and their product is at most
  51 * raid_disks.
  52 *
  53 * If far_offset is true, then the far_copies are handled a bit differently.
  54 * The copies are still in different stripes, but instead of be very far apart
  55 * on disk, there are adjacent stripes.
  56 */
  57
  58/*
  59 * Number of guaranteed r10bios in case of extreme VM load:
  60 */
  61#define NR_RAID10_BIOS 256
  62
  63/* when we get a read error on a read-only array, we redirect to another
  64 * device without failing the first device, or trying to over-write to
  65 * correct the read error.  To keep track of bad blocks on a per-bio
  66 * level, we store IO_BLOCKED in the appropriate 'bios' pointer
  67 */
  68#define IO_BLOCKED ((struct bio *)1)
  69/* When we successfully write to a known bad-block, we need to remove the
  70 * bad-block marking which must be done from process context.  So we record
  71 * the success by setting devs[n].bio to IO_MADE_GOOD
  72 */
  73#define IO_MADE_GOOD ((struct bio *)2)
  74
  75#define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
  76
  77/* When there are this many requests queued to be written by
  78 * the raid10 thread, we become 'congested' to provide back-pressure
  79 * for writeback.
  80 */
  81static int max_queued_requests = 1024;
  82
  83static void allow_barrier(struct r10conf *conf);
  84static void lower_barrier(struct r10conf *conf);
  85static int enough(struct r10conf *conf, int ignore);
  86static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
  87                                int *skipped);
  88static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio);
  89static void end_reshape_write(struct bio *bio, int error);
  90static void end_reshape(struct r10conf *conf);
  91
  92static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
  93{
  94        struct r10conf *conf = data;
  95        int size = offsetof(struct r10bio, devs[conf->copies]);
  96
  97        /* allocate a r10bio with room for raid_disks entries in the
  98         * bios array */
  99        return kzalloc(size, gfp_flags);
 100}
 101
 102static void r10bio_pool_free(void *r10_bio, void *data)
 103{
 104        kfree(r10_bio);
 105}
 106
 107/* Maximum size of each resync request */
 108#define RESYNC_BLOCK_SIZE (64*1024)
 109#define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
 110/* amount of memory to reserve for resync requests */
 111#define RESYNC_WINDOW (1024*1024)
 112/* maximum number of concurrent requests, memory permitting */
 113#define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE)
 114
 115/*
 116 * When performing a resync, we need to read and compare, so
 117 * we need as many pages are there are copies.
 118 * When performing a recovery, we need 2 bios, one for read,
 119 * one for write (we recover only one drive per r10buf)
 120 *
 121 */
 122static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 123{
 124        struct r10conf *conf = data;
 125        struct page *page;
 126        struct r10bio *r10_bio;
 127        struct bio *bio;
 128        int i, j;
 129        int nalloc;
 130
 131        r10_bio = r10bio_pool_alloc(gfp_flags, conf);
 132        if (!r10_bio)
 133                return NULL;
 134
 135        if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery) ||
 136            test_bit(MD_RECOVERY_RESHAPE, &conf->mddev->recovery))
 137                nalloc = conf->copies; /* resync */
 138        else
 139                nalloc = 2; /* recovery */
 140
 141        /*
 142         * Allocate bios.
 143         */
 144        for (j = nalloc ; j-- ; ) {
 145                bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
 146                if (!bio)
 147                        goto out_free_bio;
 148                r10_bio->devs[j].bio = bio;
 149                if (!conf->have_replacement)
 150                        continue;
 151                bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
 152                if (!bio)
 153                        goto out_free_bio;
 154                r10_bio->devs[j].repl_bio = bio;
 155        }
 156        /*
 157         * Allocate RESYNC_PAGES data pages and attach them
 158         * where needed.
 159         */
 160        for (j = 0 ; j < nalloc; j++) {
 161                struct bio *rbio = r10_bio->devs[j].repl_bio;
 162                bio = r10_bio->devs[j].bio;
 163                for (i = 0; i < RESYNC_PAGES; i++) {
 164                        if (j > 0 && !test_bit(MD_RECOVERY_SYNC,
 165                                               &conf->mddev->recovery)) {
 166                                /* we can share bv_page's during recovery
 167                                 * and reshape */
 168                                struct bio *rbio = r10_bio->devs[0].bio;
 169                                page = rbio->bi_io_vec[i].bv_page;
 170                                get_page(page);
 171                        } else
 172                                page = alloc_page(gfp_flags);
 173                        if (unlikely(!page))
 174                                goto out_free_pages;
 175
 176                        bio->bi_io_vec[i].bv_page = page;
 177                        if (rbio)
 178                                rbio->bi_io_vec[i].bv_page = page;
 179                }
 180        }
 181
 182        return r10_bio;
 183
 184out_free_pages:
 185        for ( ; i > 0 ; i--)
 186                safe_put_page(bio->bi_io_vec[i-1].bv_page);
 187        while (j--)
 188                for (i = 0; i < RESYNC_PAGES ; i++)
 189                        safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
 190        j = 0;
 191out_free_bio:
 192        for ( ; j < nalloc; j++) {
 193                if (r10_bio->devs[j].bio)
 194                        bio_put(r10_bio->devs[j].bio);
 195                if (r10_bio->devs[j].repl_bio)
 196                        bio_put(r10_bio->devs[j].repl_bio);
 197        }
 198        r10bio_pool_free(r10_bio, conf);
 199        return NULL;
 200}
 201
 202static void r10buf_pool_free(void *__r10_bio, void *data)
 203{
 204        int i;
 205        struct r10conf *conf = data;
 206        struct r10bio *r10bio = __r10_bio;
 207        int j;
 208
 209        for (j=0; j < conf->copies; j++) {
 210                struct bio *bio = r10bio->devs[j].bio;
 211                if (bio) {
 212                        for (i = 0; i < RESYNC_PAGES; i++) {
 213                                safe_put_page(bio->bi_io_vec[i].bv_page);
 214                                bio->bi_io_vec[i].bv_page = NULL;
 215                        }
 216                        bio_put(bio);
 217                }
 218                bio = r10bio->devs[j].repl_bio;
 219                if (bio)
 220                        bio_put(bio);
 221        }
 222        r10bio_pool_free(r10bio, conf);
 223}
 224
 225static void put_all_bios(struct r10conf *conf, struct r10bio *r10_bio)
 226{
 227        int i;
 228
 229        for (i = 0; i < conf->copies; i++) {
 230                struct bio **bio = & r10_bio->devs[i].bio;
 231                if (!BIO_SPECIAL(*bio))
 232                        bio_put(*bio);
 233                *bio = NULL;
 234                bio = &r10_bio->devs[i].repl_bio;
 235                if (r10_bio->read_slot < 0 && !BIO_SPECIAL(*bio))
 236                        bio_put(*bio);
 237                *bio = NULL;
 238        }
 239}
 240
 241static void free_r10bio(struct r10bio *r10_bio)
 242{
 243        struct r10conf *conf = r10_bio->mddev->private;
 244
 245        put_all_bios(conf, r10_bio);
 246        mempool_free(r10_bio, conf->r10bio_pool);
 247}
 248
 249static void put_buf(struct r10bio *r10_bio)
 250{
 251        struct r10conf *conf = r10_bio->mddev->private;
 252
 253        mempool_free(r10_bio, conf->r10buf_pool);
 254
 255        lower_barrier(conf);
 256}
 257
 258static void reschedule_retry(struct r10bio *r10_bio)
 259{
 260        unsigned long flags;
 261        struct mddev *mddev = r10_bio->mddev;
 262        struct r10conf *conf = mddev->private;
 263
 264        spin_lock_irqsave(&conf->device_lock, flags);
 265        list_add(&r10_bio->retry_list, &conf->retry_list);
 266        conf->nr_queued ++;
 267        spin_unlock_irqrestore(&conf->device_lock, flags);
 268
 269        /* wake up frozen array... */
 270        wake_up(&conf->wait_barrier);
 271
 272        md_wakeup_thread(mddev->thread);
 273}
 274
 275/*
 276 * raid_end_bio_io() is called when we have finished servicing a mirrored
 277 * operation and are ready to return a success/failure code to the buffer
 278 * cache layer.
 279 */
 280static void raid_end_bio_io(struct r10bio *r10_bio)
 281{
 282        struct bio *bio = r10_bio->master_bio;
 283        int done;
 284        struct r10conf *conf = r10_bio->mddev->private;
 285
 286        if (bio->bi_phys_segments) {
 287                unsigned long flags;
 288                spin_lock_irqsave(&conf->device_lock, flags);
 289                bio->bi_phys_segments--;
 290                done = (bio->bi_phys_segments == 0);
 291                spin_unlock_irqrestore(&conf->device_lock, flags);
 292        } else
 293                done = 1;
 294        if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
 295                clear_bit(BIO_UPTODATE, &bio->bi_flags);
 296        if (done) {
 297                bio_endio(bio, 0);
 298                /*
 299                 * Wake up any possible resync thread that waits for the device
 300                 * to go idle.
 301                 */
 302                allow_barrier(conf);
 303        }
 304        free_r10bio(r10_bio);
 305}
 306
 307/*
 308 * Update disk head position estimator based on IRQ completion info.
 309 */
 310static inline void update_head_pos(int slot, struct r10bio *r10_bio)
 311{
 312        struct r10conf *conf = r10_bio->mddev->private;
 313
 314        conf->mirrors[r10_bio->devs[slot].devnum].head_position =
 315                r10_bio->devs[slot].addr + (r10_bio->sectors);
 316}
 317
 318/*
 319 * Find the disk number which triggered given bio
 320 */
 321static int find_bio_disk(struct r10conf *conf, struct r10bio *r10_bio,
 322                         struct bio *bio, int *slotp, int *replp)
 323{
 324        int slot;
 325        int repl = 0;
 326
 327        for (slot = 0; slot < conf->copies; slot++) {
 328                if (r10_bio->devs[slot].bio == bio)
 329                        break;
 330                if (r10_bio->devs[slot].repl_bio == bio) {
 331                        repl = 1;
 332                        break;
 333                }
 334        }
 335
 336        BUG_ON(slot == conf->copies);
 337        update_head_pos(slot, r10_bio);
 338
 339        if (slotp)
 340                *slotp = slot;
 341        if (replp)
 342                *replp = repl;
 343        return r10_bio->devs[slot].devnum;
 344}
 345
 346static void raid10_end_read_request(struct bio *bio, int error)
 347{
 348        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 349        struct r10bio *r10_bio = bio->bi_private;
 350        int slot, dev;
 351        struct md_rdev *rdev;
 352        struct r10conf *conf = r10_bio->mddev->private;
 353
 354
 355        slot = r10_bio->read_slot;
 356        dev = r10_bio->devs[slot].devnum;
 357        rdev = r10_bio->devs[slot].rdev;
 358        /*
 359         * this branch is our 'one mirror IO has finished' event handler:
 360         */
 361        update_head_pos(slot, r10_bio);
 362
 363        if (uptodate) {
 364                /*
 365                 * Set R10BIO_Uptodate in our master bio, so that
 366                 * we will return a good error code to the higher
 367                 * levels even if IO on some other mirrored buffer fails.
 368                 *
 369                 * The 'master' represents the composite IO operation to
 370                 * user-side. So if something waits for IO, then it will
 371                 * wait for the 'master' bio.
 372                 */
 373                set_bit(R10BIO_Uptodate, &r10_bio->state);
 374        } else {
 375                /* If all other devices that store this block have
 376                 * failed, we want to return the error upwards rather
 377                 * than fail the last device.  Here we redefine
 378                 * "uptodate" to mean "Don't want to retry"
 379                 */
 380                unsigned long flags;
 381                spin_lock_irqsave(&conf->device_lock, flags);
 382                if (!enough(conf, rdev->raid_disk))
 383                        uptodate = 1;
 384                spin_unlock_irqrestore(&conf->device_lock, flags);
 385        }
 386        if (uptodate) {
 387                raid_end_bio_io(r10_bio);
 388                rdev_dec_pending(rdev, conf->mddev);
 389        } else {
 390                /*
 391                 * oops, read error - keep the refcount on the rdev
 392                 */
 393                char b[BDEVNAME_SIZE];
 394                printk_ratelimited(KERN_ERR
 395                                   "md/raid10:%s: %s: rescheduling sector %llu\n",
 396                                   mdname(conf->mddev),
 397                                   bdevname(rdev->bdev, b),
 398                                   (unsigned long long)r10_bio->sector);
 399                set_bit(R10BIO_ReadError, &r10_bio->state);
 400                reschedule_retry(r10_bio);
 401        }
 402}
 403
 404static void close_write(struct r10bio *r10_bio)
 405{
 406        /* clear the bitmap if all writes complete successfully */
 407        bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
 408                        r10_bio->sectors,
 409                        !test_bit(R10BIO_Degraded, &r10_bio->state),
 410                        0);
 411        md_write_end(r10_bio->mddev);
 412}
 413
 414static void one_write_done(struct r10bio *r10_bio)
 415{
 416        if (atomic_dec_and_test(&r10_bio->remaining)) {
 417                if (test_bit(R10BIO_WriteError, &r10_bio->state))
 418                        reschedule_retry(r10_bio);
 419                else {
 420                        close_write(r10_bio);
 421                        if (test_bit(R10BIO_MadeGood, &r10_bio->state))
 422                                reschedule_retry(r10_bio);
 423                        else
 424                                raid_end_bio_io(r10_bio);
 425                }
 426        }
 427}
 428
 429static void raid10_end_write_request(struct bio *bio, int error)
 430{
 431        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 432        struct r10bio *r10_bio = bio->bi_private;
 433        int dev;
 434        int dec_rdev = 1;
 435        struct r10conf *conf = r10_bio->mddev->private;
 436        int slot, repl;
 437        struct md_rdev *rdev = NULL;
 438
 439        dev = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
 440
 441        if (repl)
 442                rdev = conf->mirrors[dev].replacement;
 443        if (!rdev) {
 444                smp_rmb();
 445                repl = 0;
 446                rdev = conf->mirrors[dev].rdev;
 447        }
 448        /*
 449         * this branch is our 'one mirror IO has finished' event handler:
 450         */
 451        if (!uptodate) {
 452                if (repl)
 453                        /* Never record new bad blocks to replacement,
 454                         * just fail it.
 455                         */
 456                        md_error(rdev->mddev, rdev);
 457                else {
 458                        set_bit(WriteErrorSeen, &rdev->flags);
 459                        if (!test_and_set_bit(WantReplacement, &rdev->flags))
 460                                set_bit(MD_RECOVERY_NEEDED,
 461                                        &rdev->mddev->recovery);
 462                        set_bit(R10BIO_WriteError, &r10_bio->state);
 463                        dec_rdev = 0;
 464                }
 465        } else {
 466                /*
 467                 * Set R10BIO_Uptodate in our master bio, so that
 468                 * we will return a good error code for to the higher
 469                 * levels even if IO on some other mirrored buffer fails.
 470                 *
 471                 * The 'master' represents the composite IO operation to
 472                 * user-side. So if something waits for IO, then it will
 473                 * wait for the 'master' bio.
 474                 */
 475                sector_t first_bad;
 476                int bad_sectors;
 477
 478                set_bit(R10BIO_Uptodate, &r10_bio->state);
 479
 480                /* Maybe we can clear some bad blocks. */
 481                if (is_badblock(rdev,
 482                                r10_bio->devs[slot].addr,
 483                                r10_bio->sectors,
 484                                &first_bad, &bad_sectors)) {
 485                        bio_put(bio);
 486                        if (repl)
 487                                r10_bio->devs[slot].repl_bio = IO_MADE_GOOD;
 488                        else
 489                                r10_bio->devs[slot].bio = IO_MADE_GOOD;
 490                        dec_rdev = 0;
 491                        set_bit(R10BIO_MadeGood, &r10_bio->state);
 492                }
 493        }
 494
 495        /*
 496         *
 497         * Let's see if all mirrored write operations have finished
 498         * already.
 499         */
 500        one_write_done(r10_bio);
 501        if (dec_rdev)
 502                rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 503}
 504
 505/*
 506 * RAID10 layout manager
 507 * As well as the chunksize and raid_disks count, there are two
 508 * parameters: near_copies and far_copies.
 509 * near_copies * far_copies must be <= raid_disks.
 510 * Normally one of these will be 1.
 511 * If both are 1, we get raid0.
 512 * If near_copies == raid_disks, we get raid1.
 513 *
 514 * Chunks are laid out in raid0 style with near_copies copies of the
 515 * first chunk, followed by near_copies copies of the next chunk and
 516 * so on.
 517 * If far_copies > 1, then after 1/far_copies of the array has been assigned
 518 * as described above, we start again with a device offset of near_copies.
 519 * So we effectively have another copy of the whole array further down all
 520 * the drives, but with blocks on different drives.
 521 * With this layout, and block is never stored twice on the one device.
 522 *
 523 * raid10_find_phys finds the sector offset of a given virtual sector
 524 * on each device that it is on.
 525 *
 526 * raid10_find_virt does the reverse mapping, from a device and a
 527 * sector offset to a virtual address
 528 */
 529
 530static void __raid10_find_phys(struct geom *geo, struct r10bio *r10bio)
 531{
 532        int n,f;
 533        sector_t sector;
 534        sector_t chunk;
 535        sector_t stripe;
 536        int dev;
 537        int slot = 0;
 538
 539        /* now calculate first sector/dev */
 540        chunk = r10bio->sector >> geo->chunk_shift;
 541        sector = r10bio->sector & geo->chunk_mask;
 542
 543        chunk *= geo->near_copies;
 544        stripe = chunk;
 545        dev = sector_div(stripe, geo->raid_disks);
 546        if (geo->far_offset)
 547                stripe *= geo->far_copies;
 548
 549        sector += stripe << geo->chunk_shift;
 550
 551        /* and calculate all the others */
 552        for (n = 0; n < geo->near_copies; n++) {
 553                int d = dev;
 554                sector_t s = sector;
 555                r10bio->devs[slot].addr = sector;
 556                r10bio->devs[slot].devnum = d;
 557                slot++;
 558
 559                for (f = 1; f < geo->far_copies; f++) {
 560                        d += geo->near_copies;
 561                        if (d >= geo->raid_disks)
 562                                d -= geo->raid_disks;
 563                        s += geo->stride;
 564                        r10bio->devs[slot].devnum = d;
 565                        r10bio->devs[slot].addr = s;
 566                        slot++;
 567                }
 568                dev++;
 569                if (dev >= geo->raid_disks) {
 570                        dev = 0;
 571                        sector += (geo->chunk_mask + 1);
 572                }
 573        }
 574}
 575
 576static void raid10_find_phys(struct r10conf *conf, struct r10bio *r10bio)
 577{
 578        struct geom *geo = &conf->geo;
 579
 580        if (conf->reshape_progress != MaxSector &&
 581            ((r10bio->sector >= conf->reshape_progress) !=
 582             conf->mddev->reshape_backwards)) {
 583                set_bit(R10BIO_Previous, &r10bio->state);
 584                geo = &conf->prev;
 585        } else
 586                clear_bit(R10BIO_Previous, &r10bio->state);
 587
 588        __raid10_find_phys(geo, r10bio);
 589}
 590
 591static sector_t raid10_find_virt(struct r10conf *conf, sector_t sector, int dev)
 592{
 593        sector_t offset, chunk, vchunk;
 594        /* Never use conf->prev as this is only called during resync
 595         * or recovery, so reshape isn't happening
 596         */
 597        struct geom *geo = &conf->geo;
 598
 599        offset = sector & geo->chunk_mask;
 600        if (geo->far_offset) {
 601                int fc;
 602                chunk = sector >> geo->chunk_shift;
 603                fc = sector_div(chunk, geo->far_copies);
 604                dev -= fc * geo->near_copies;
 605                if (dev < 0)
 606                        dev += geo->raid_disks;
 607        } else {
 608                while (sector >= geo->stride) {
 609                        sector -= geo->stride;
 610                        if (dev < geo->near_copies)
 611                                dev += geo->raid_disks - geo->near_copies;
 612                        else
 613                                dev -= geo->near_copies;
 614                }
 615                chunk = sector >> geo->chunk_shift;
 616        }
 617        vchunk = chunk * geo->raid_disks + dev;
 618        sector_div(vchunk, geo->near_copies);
 619        return (vchunk << geo->chunk_shift) + offset;
 620}
 621
 622/**
 623 *      raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
 624 *      @q: request queue
 625 *      @bvm: properties of new bio
 626 *      @biovec: the request that could be merged to it.
 627 *
 628 *      Return amount of bytes we can accept at this offset
 629 *      This requires checking for end-of-chunk if near_copies != raid_disks,
 630 *      and for subordinate merge_bvec_fns if merge_check_needed.
 631 */
 632static int raid10_mergeable_bvec(struct request_queue *q,
 633                                 struct bvec_merge_data *bvm,
 634                                 struct bio_vec *biovec)
 635{
 636        struct mddev *mddev = q->queuedata;
 637        struct r10conf *conf = mddev->private;
 638        sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 639        int max;
 640        unsigned int chunk_sectors;
 641        unsigned int bio_sectors = bvm->bi_size >> 9;
 642        struct geom *geo = &conf->geo;
 643
 644        chunk_sectors = (conf->geo.chunk_mask & conf->prev.chunk_mask) + 1;
 645        if (conf->reshape_progress != MaxSector &&
 646            ((sector >= conf->reshape_progress) !=
 647             conf->mddev->reshape_backwards))
 648                geo = &conf->prev;
 649
 650        if (geo->near_copies < geo->raid_disks) {
 651                max = (chunk_sectors - ((sector & (chunk_sectors - 1))
 652                                        + bio_sectors)) << 9;
 653                if (max < 0)
 654                        /* bio_add cannot handle a negative return */
 655                        max = 0;
 656                if (max <= biovec->bv_len && bio_sectors == 0)
 657                        return biovec->bv_len;
 658        } else
 659                max = biovec->bv_len;
 660
 661        if (mddev->merge_check_needed) {
 662                struct {
 663                        struct r10bio r10_bio;
 664                        struct r10dev devs[conf->copies];
 665                } on_stack;
 666                struct r10bio *r10_bio = &on_stack.r10_bio;
 667                int s;
 668                if (conf->reshape_progress != MaxSector) {
 669                        /* Cannot give any guidance during reshape */
 670                        if (max <= biovec->bv_len && bio_sectors == 0)
 671                                return biovec->bv_len;
 672                        return 0;
 673                }
 674                r10_bio->sector = sector;
 675                raid10_find_phys(conf, r10_bio);
 676                rcu_read_lock();
 677                for (s = 0; s < conf->copies; s++) {
 678                        int disk = r10_bio->devs[s].devnum;
 679                        struct md_rdev *rdev = rcu_dereference(
 680                                conf->mirrors[disk].rdev);
 681                        if (rdev && !test_bit(Faulty, &rdev->flags)) {
 682                                struct request_queue *q =
 683                                        bdev_get_queue(rdev->bdev);
 684                                if (q->merge_bvec_fn) {
 685                                        bvm->bi_sector = r10_bio->devs[s].addr
 686                                                + rdev->data_offset;
 687                                        bvm->bi_bdev = rdev->bdev;
 688                                        max = min(max, q->merge_bvec_fn(
 689                                                          q, bvm, biovec));
 690                                }
 691                        }
 692                        rdev = rcu_dereference(conf->mirrors[disk].replacement);
 693                        if (rdev && !test_bit(Faulty, &rdev->flags)) {
 694                                struct request_queue *q =
 695                                        bdev_get_queue(rdev->bdev);
 696                                if (q->merge_bvec_fn) {
 697                                        bvm->bi_sector = r10_bio->devs[s].addr
 698                                                + rdev->data_offset;
 699                                        bvm->bi_bdev = rdev->bdev;
 700                                        max = min(max, q->merge_bvec_fn(
 701                                                          q, bvm, biovec));
 702                                }
 703                        }
 704                }
 705                rcu_read_unlock();
 706        }
 707        return max;
 708}
 709
 710/*
 711 * This routine returns the disk from which the requested read should
 712 * be done. There is a per-array 'next expected sequential IO' sector
 713 * number - if this matches on the next IO then we use the last disk.
 714 * There is also a per-disk 'last know head position' sector that is
 715 * maintained from IRQ contexts, both the normal and the resync IO
 716 * completion handlers update this position correctly. If there is no
 717 * perfect sequential match then we pick the disk whose head is closest.
 718 *
 719 * If there are 2 mirrors in the same 2 devices, performance degrades
 720 * because position is mirror, not device based.
 721 *
 722 * The rdev for the device selected will have nr_pending incremented.
 723 */
 724
 725/*
 726 * FIXME: possibly should rethink readbalancing and do it differently
 727 * depending on near_copies / far_copies geometry.
 728 */
 729static struct md_rdev *read_balance(struct r10conf *conf,
 730                                    struct r10bio *r10_bio,
 731                                    int *max_sectors)
 732{
 733        const sector_t this_sector = r10_bio->sector;
 734        int disk, slot;
 735        int sectors = r10_bio->sectors;
 736        int best_good_sectors;
 737        sector_t new_distance, best_dist;
 738        struct md_rdev *best_rdev, *rdev = NULL;
 739        int do_balance;
 740        int best_slot;
 741        struct geom *geo = &conf->geo;
 742
 743        raid10_find_phys(conf, r10_bio);
 744        rcu_read_lock();
 745retry:
 746        sectors = r10_bio->sectors;
 747        best_slot = -1;
 748        best_rdev = NULL;
 749        best_dist = MaxSector;
 750        best_good_sectors = 0;
 751        do_balance = 1;
 752        /*
 753         * Check if we can balance. We can balance on the whole
 754         * device if no resync is going on (recovery is ok), or below
 755         * the resync window. We take the first readable disk when
 756         * above the resync window.
 757         */
 758        if (conf->mddev->recovery_cp < MaxSector
 759            && (this_sector + sectors >= conf->next_resync))
 760                do_balance = 0;
 761
 762        for (slot = 0; slot < conf->copies ; slot++) {
 763                sector_t first_bad;
 764                int bad_sectors;
 765                sector_t dev_sector;
 766
 767                if (r10_bio->devs[slot].bio == IO_BLOCKED)
 768                        continue;
 769                disk = r10_bio->devs[slot].devnum;
 770                rdev = rcu_dereference(conf->mirrors[disk].replacement);
 771                if (rdev == NULL || test_bit(Faulty, &rdev->flags) ||
 772                    test_bit(Unmerged, &rdev->flags) ||
 773                    r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
 774                        rdev = rcu_dereference(conf->mirrors[disk].rdev);
 775                if (rdev == NULL ||
 776                    test_bit(Faulty, &rdev->flags) ||
 777                    test_bit(Unmerged, &rdev->flags))
 778                        continue;
 779                if (!test_bit(In_sync, &rdev->flags) &&
 780                    r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
 781                        continue;
 782
 783                dev_sector = r10_bio->devs[slot].addr;
 784                if (is_badblock(rdev, dev_sector, sectors,
 785                                &first_bad, &bad_sectors)) {
 786                        if (best_dist < MaxSector)
 787                                /* Already have a better slot */
 788                                continue;
 789                        if (first_bad <= dev_sector) {
 790                                /* Cannot read here.  If this is the
 791                                 * 'primary' device, then we must not read
 792                                 * beyond 'bad_sectors' from another device.
 793                                 */
 794                                bad_sectors -= (dev_sector - first_bad);
 795                                if (!do_balance && sectors > bad_sectors)
 796                                        sectors = bad_sectors;
 797                                if (best_good_sectors > sectors)
 798                                        best_good_sectors = sectors;
 799                        } else {
 800                                sector_t good_sectors =
 801                                        first_bad - dev_sector;
 802                                if (good_sectors > best_good_sectors) {
 803                                        best_good_sectors = good_sectors;
 804                                        best_slot = slot;
 805                                        best_rdev = rdev;
 806                                }
 807                                if (!do_balance)
 808                                        /* Must read from here */
 809                                        break;
 810                        }
 811                        continue;
 812                } else
 813                        best_good_sectors = sectors;
 814
 815                if (!do_balance)
 816                        break;
 817
 818                /* This optimisation is debatable, and completely destroys
 819                 * sequential read speed for 'far copies' arrays.  So only
 820                 * keep it for 'near' arrays, and review those later.
 821                 */
 822                if (geo->near_copies > 1 && !atomic_read(&rdev->nr_pending))
 823                        break;
 824
 825                /* for far > 1 always use the lowest address */
 826                if (geo->far_copies > 1)
 827                        new_distance = r10_bio->devs[slot].addr;
 828                else
 829                        new_distance = abs(r10_bio->devs[slot].addr -
 830                                           conf->mirrors[disk].head_position);
 831                if (new_distance < best_dist) {
 832                        best_dist = new_distance;
 833                        best_slot = slot;
 834                        best_rdev = rdev;
 835                }
 836        }
 837        if (slot >= conf->copies) {
 838                slot = best_slot;
 839                rdev = best_rdev;
 840        }
 841
 842        if (slot >= 0) {
 843                atomic_inc(&rdev->nr_pending);
 844                if (test_bit(Faulty, &rdev->flags)) {
 845                        /* Cannot risk returning a device that failed
 846                         * before we inc'ed nr_pending
 847                         */
 848                        rdev_dec_pending(rdev, conf->mddev);
 849                        goto retry;
 850                }
 851                r10_bio->read_slot = slot;
 852        } else
 853                rdev = NULL;
 854        rcu_read_unlock();
 855        *max_sectors = best_good_sectors;
 856
 857        return rdev;
 858}
 859
 860int md_raid10_congested(struct mddev *mddev, int bits)
 861{
 862        struct r10conf *conf = mddev->private;
 863        int i, ret = 0;
 864
 865        if ((bits & (1 << BDI_async_congested)) &&
 866            conf->pending_count >= max_queued_requests)
 867                return 1;
 868
 869        rcu_read_lock();
 870        for (i = 0;
 871             (i < conf->geo.raid_disks || i < conf->prev.raid_disks)
 872                     && ret == 0;
 873             i++) {
 874                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
 875                if (rdev && !test_bit(Faulty, &rdev->flags)) {
 876                        struct request_queue *q = bdev_get_queue(rdev->bdev);
 877
 878                        ret |= bdi_congested(&q->backing_dev_info, bits);
 879                }
 880        }
 881        rcu_read_unlock();
 882        return ret;
 883}
 884EXPORT_SYMBOL_GPL(md_raid10_congested);
 885
 886static int raid10_congested(void *data, int bits)
 887{
 888        struct mddev *mddev = data;
 889
 890        return mddev_congested(mddev, bits) ||
 891                md_raid10_congested(mddev, bits);
 892}
 893
 894static void flush_pending_writes(struct r10conf *conf)
 895{
 896        /* Any writes that have been queued but are awaiting
 897         * bitmap updates get flushed here.
 898         */
 899        spin_lock_irq(&conf->device_lock);
 900
 901        if (conf->pending_bio_list.head) {
 902                struct bio *bio;
 903                bio = bio_list_get(&conf->pending_bio_list);
 904                conf->pending_count = 0;
 905                spin_unlock_irq(&conf->device_lock);
 906                /* flush any pending bitmap writes to disk
 907                 * before proceeding w/ I/O */
 908                bitmap_unplug(conf->mddev->bitmap);
 909                wake_up(&conf->wait_barrier);
 910
 911                while (bio) { /* submit pending writes */
 912                        struct bio *next = bio->bi_next;
 913                        bio->bi_next = NULL;
 914                        generic_make_request(bio);
 915                        bio = next;
 916                }
 917        } else
 918                spin_unlock_irq(&conf->device_lock);
 919}
 920
 921/* Barriers....
 922 * Sometimes we need to suspend IO while we do something else,
 923 * either some resync/recovery, or reconfigure the array.
 924 * To do this we raise a 'barrier'.
 925 * The 'barrier' is a counter that can be raised multiple times
 926 * to count how many activities are happening which preclude
 927 * normal IO.
 928 * We can only raise the barrier if there is no pending IO.
 929 * i.e. if nr_pending == 0.
 930 * We choose only to raise the barrier if no-one is waiting for the
 931 * barrier to go down.  This means that as soon as an IO request
 932 * is ready, no other operations which require a barrier will start
 933 * until the IO request has had a chance.
 934 *
 935 * So: regular IO calls 'wait_barrier'.  When that returns there
 936 *    is no backgroup IO happening,  It must arrange to call
 937 *    allow_barrier when it has finished its IO.
 938 * backgroup IO calls must call raise_barrier.  Once that returns
 939 *    there is no normal IO happeing.  It must arrange to call
 940 *    lower_barrier when the particular background IO completes.
 941 */
 942
 943static void raise_barrier(struct r10conf *conf, int force)
 944{
 945        BUG_ON(force && !conf->barrier);
 946        spin_lock_irq(&conf->resync_lock);
 947
 948        /* Wait until no block IO is waiting (unless 'force') */
 949        wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
 950                            conf->resync_lock, );
 951
 952        /* block any new IO from starting */
 953        conf->barrier++;
 954
 955        /* Now wait for all pending IO to complete */
 956        wait_event_lock_irq(conf->wait_barrier,
 957                            !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 958                            conf->resync_lock, );
 959
 960        spin_unlock_irq(&conf->resync_lock);
 961}
 962
 963static void lower_barrier(struct r10conf *conf)
 964{
 965        unsigned long flags;
 966        spin_lock_irqsave(&conf->resync_lock, flags);
 967        conf->barrier--;
 968        spin_unlock_irqrestore(&conf->resync_lock, flags);
 969        wake_up(&conf->wait_barrier);
 970}
 971
 972static void wait_barrier(struct r10conf *conf)
 973{
 974        spin_lock_irq(&conf->resync_lock);
 975        if (conf->barrier) {
 976                conf->nr_waiting++;
 977                /* Wait for the barrier to drop.
 978                 * However if there are already pending
 979                 * requests (preventing the barrier from
 980                 * rising completely), and the
 981                 * pre-process bio queue isn't empty,
 982                 * then don't wait, as we need to empty
 983                 * that queue to get the nr_pending
 984                 * count down.
 985                 */
 986                wait_event_lock_irq(conf->wait_barrier,
 987                                    !conf->barrier ||
 988                                    (conf->nr_pending &&
 989                                     current->bio_list &&
 990                                     !bio_list_empty(current->bio_list)),
 991                                    conf->resync_lock,
 992                        );
 993                conf->nr_waiting--;
 994        }
 995        conf->nr_pending++;
 996        spin_unlock_irq(&conf->resync_lock);
 997}
 998
 999static void allow_barrier(struct r10conf *conf)
1000{
1001        unsigned long flags;
1002        spin_lock_irqsave(&conf->resync_lock, flags);
1003        conf->nr_pending--;
1004        spin_unlock_irqrestore(&conf->resync_lock, flags);
1005        wake_up(&conf->wait_barrier);
1006}
1007
1008static void freeze_array(struct r10conf *conf)
1009{
1010        /* stop syncio and normal IO and wait for everything to
1011         * go quiet.
1012         * We increment barrier and nr_waiting, and then
1013         * wait until nr_pending match nr_queued+1
1014         * This is called in the context of one normal IO request
1015         * that has failed. Thus any sync request that might be pending
1016         * will be blocked by nr_pending, and we need to wait for
1017         * pending IO requests to complete or be queued for re-try.
1018         * Thus the number queued (nr_queued) plus this request (1)
1019         * must match the number of pending IOs (nr_pending) before
1020         * we continue.
1021         */
1022        spin_lock_irq(&conf->resync_lock);
1023        conf->barrier++;
1024        conf->nr_waiting++;
1025        wait_event_lock_irq(conf->wait_barrier,
1026                            conf->nr_pending == conf->nr_queued+1,
1027                            conf->resync_lock,
1028                            flush_pending_writes(conf));
1029
1030        spin_unlock_irq(&conf->resync_lock);
1031}
1032
1033static void unfreeze_array(struct r10conf *conf)
1034{
1035        /* reverse the effect of the freeze */
1036        spin_lock_irq(&conf->resync_lock);
1037        conf->barrier--;
1038        conf->nr_waiting--;
1039        wake_up(&conf->wait_barrier);
1040        spin_unlock_irq(&conf->resync_lock);
1041}
1042
1043static sector_t choose_data_offset(struct r10bio *r10_bio,
1044                                   struct md_rdev *rdev)
1045{
1046        if (!test_bit(MD_RECOVERY_RESHAPE, &rdev->mddev->recovery) ||
1047            test_bit(R10BIO_Previous, &r10_bio->state))
1048                return rdev->data_offset;
1049        else
1050                return rdev->new_data_offset;
1051}
1052
1053static void make_request(struct mddev *mddev, struct bio * bio)
1054{
1055        struct r10conf *conf = mddev->private;
1056        struct r10bio *r10_bio;
1057        struct bio *read_bio;
1058        int i;
1059        sector_t chunk_mask = (conf->geo.chunk_mask & conf->prev.chunk_mask);
1060        int chunk_sects = chunk_mask + 1;
1061        const int rw = bio_data_dir(bio);
1062        const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
1063        const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
1064        unsigned long flags;
1065        struct md_rdev *blocked_rdev;
1066        int sectors_handled;
1067        int max_sectors;
1068        int sectors;
1069
1070        if (unlikely(bio->bi_rw & REQ_FLUSH)) {
1071                md_flush_request(mddev, bio);
1072                return;
1073        }
1074
1075        /* If this request crosses a chunk boundary, we need to
1076         * split it.  This will only happen for 1 PAGE (or less) requests.
1077         */
1078        if (unlikely((bio->bi_sector & chunk_mask) + (bio->bi_size >> 9)
1079                     > chunk_sects
1080                     && (conf->geo.near_copies < conf->geo.raid_disks
1081                         || conf->prev.near_copies < conf->prev.raid_disks))) {
1082                struct bio_pair *bp;
1083                /* Sanity check -- queue functions should prevent this happening */
1084                if (bio->bi_vcnt != 1 ||
1085                    bio->bi_idx != 0)
1086                        goto bad_map;
1087                /* This is a one page bio that upper layers
1088                 * refuse to split for us, so we need to split it.
1089                 */
1090                bp = bio_split(bio,
1091                               chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
1092
1093                /* Each of these 'make_request' calls will call 'wait_barrier'.
1094                 * If the first succeeds but the second blocks due to the resync
1095                 * thread raising the barrier, we will deadlock because the
1096                 * IO to the underlying device will be queued in generic_make_request
1097                 * and will never complete, so will never reduce nr_pending.
1098                 * So increment nr_waiting here so no new raise_barriers will
1099                 * succeed, and so the second wait_barrier cannot block.
1100                 */
1101                spin_lock_irq(&conf->resync_lock);
1102                conf->nr_waiting++;
1103                spin_unlock_irq(&conf->resync_lock);
1104
1105                make_request(mddev, &bp->bio1);
1106                make_request(mddev, &bp->bio2);
1107
1108                spin_lock_irq(&conf->resync_lock);
1109                conf->nr_waiting--;
1110                wake_up(&conf->wait_barrier);
1111                spin_unlock_irq(&conf->resync_lock);
1112
1113                bio_pair_release(bp);
1114                return;
1115        bad_map:
1116                printk("md/raid10:%s: make_request bug: can't convert block across chunks"
1117                       " or bigger than %dk %llu %d\n", mdname(mddev), chunk_sects/2,
1118                       (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
1119
1120                bio_io_error(bio);
1121                return;
1122        }
1123
1124        md_write_start(mddev, bio);
1125
1126        /*
1127         * Register the new request and wait if the reconstruction
1128         * thread has put up a bar for new requests.
1129         * Continue immediately if no resync is active currently.
1130         */
1131        wait_barrier(conf);
1132
1133        sectors = bio->bi_size >> 9;
1134        while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
1135            bio->bi_sector < conf->reshape_progress &&
1136            bio->bi_sector + sectors > conf->reshape_progress) {
1137                /* IO spans the reshape position.  Need to wait for
1138                 * reshape to pass
1139                 */
1140                allow_barrier(conf);
1141                wait_event(conf->wait_barrier,
1142                           conf->reshape_progress <= bio->bi_sector ||
1143                           conf->reshape_progress >= bio->bi_sector + sectors);
1144                wait_barrier(conf);
1145        }
1146        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
1147            bio_data_dir(bio) == WRITE &&
1148            (mddev->reshape_backwards
1149             ? (bio->bi_sector < conf->reshape_safe &&
1150                bio->bi_sector + sectors > conf->reshape_progress)
1151             : (bio->bi_sector + sectors > conf->reshape_safe &&
1152                bio->bi_sector < conf->reshape_progress))) {
1153                /* Need to update reshape_position in metadata */
1154                mddev->reshape_position = conf->reshape_progress;
1155                set_bit(MD_CHANGE_DEVS, &mddev->flags);
1156                set_bit(MD_CHANGE_PENDING, &mddev->flags);
1157                md_wakeup_thread(mddev->thread);
1158                wait_event(mddev->sb_wait,
1159                           !test_bit(MD_CHANGE_PENDING, &mddev->flags));
1160
1161                conf->reshape_safe = mddev->reshape_position;
1162        }
1163
1164        r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1165
1166        r10_bio->master_bio = bio;
1167        r10_bio->sectors = sectors;
1168
1169        r10_bio->mddev = mddev;
1170        r10_bio->sector = bio->bi_sector;
1171        r10_bio->state = 0;
1172
1173        /* We might need to issue multiple reads to different
1174         * devices if there are bad blocks around, so we keep
1175         * track of the number of reads in bio->bi_phys_segments.
1176         * If this is 0, there is only one r10_bio and no locking
1177         * will be needed when the request completes.  If it is
1178         * non-zero, then it is the number of not-completed requests.
1179         */
1180        bio->bi_phys_segments = 0;
1181        clear_bit(BIO_SEG_VALID, &bio->bi_flags);
1182
1183        if (rw == READ) {
1184                /*
1185                 * read balancing logic:
1186                 */
1187                struct md_rdev *rdev;
1188                int slot;
1189
1190read_again:
1191                rdev = read_balance(conf, r10_bio, &max_sectors);
1192                if (!rdev) {
1193                        raid_end_bio_io(r10_bio);
1194                        return;
1195                }
1196                slot = r10_bio->read_slot;
1197
1198                read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1199                md_trim_bio(read_bio, r10_bio->sector - bio->bi_sector,
1200                            max_sectors);
1201
1202                r10_bio->devs[slot].bio = read_bio;
1203                r10_bio->devs[slot].rdev = rdev;
1204
1205                read_bio->bi_sector = r10_bio->devs[slot].addr +
1206                        choose_data_offset(r10_bio, rdev);
1207                read_bio->bi_bdev = rdev->bdev;
1208                read_bio->bi_end_io = raid10_end_read_request;
1209                read_bio->bi_rw = READ | do_sync;
1210                read_bio->bi_private = r10_bio;
1211
1212                if (max_sectors < r10_bio->sectors) {
1213                        /* Could not read all from this device, so we will
1214                         * need another r10_bio.
1215                         */
1216                        sectors_handled = (r10_bio->sectors + max_sectors
1217                                           - bio->bi_sector);
1218                        r10_bio->sectors = max_sectors;
1219                        spin_lock_irq(&conf->device_lock);
1220                        if (bio->bi_phys_segments == 0)
1221                                bio->bi_phys_segments = 2;
1222                        else
1223                                bio->bi_phys_segments++;
1224                        spin_unlock(&conf->device_lock);
1225                        /* Cannot call generic_make_request directly
1226                         * as that will be queued in __generic_make_request
1227                         * and subsequent mempool_alloc might block
1228                         * waiting for it.  so hand bio over to raid10d.
1229                         */
1230                        reschedule_retry(r10_bio);
1231
1232                        r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1233
1234                        r10_bio->master_bio = bio;
1235                        r10_bio->sectors = ((bio->bi_size >> 9)
1236                                            - sectors_handled);
1237                        r10_bio->state = 0;
1238                        r10_bio->mddev = mddev;
1239                        r10_bio->sector = bio->bi_sector + sectors_handled;
1240                        goto read_again;
1241                } else
1242                        generic_make_request(read_bio);
1243                return;
1244        }
1245
1246        /*
1247         * WRITE:
1248         */
1249        if (conf->pending_count >= max_queued_requests) {
1250                md_wakeup_thread(mddev->thread);
1251                wait_event(conf->wait_barrier,
1252                           conf->pending_count < max_queued_requests);
1253        }
1254        /* first select target devices under rcu_lock and
1255         * inc refcount on their rdev.  Record them by setting
1256         * bios[x] to bio
1257         * If there are known/acknowledged bad blocks on any device
1258         * on which we have seen a write error, we want to avoid
1259         * writing to those blocks.  This potentially requires several
1260         * writes to write around the bad blocks.  Each set of writes
1261         * gets its own r10_bio with a set of bios attached.  The number
1262         * of r10_bios is recored in bio->bi_phys_segments just as with
1263         * the read case.
1264         */
1265
1266        r10_bio->read_slot = -1; /* make sure repl_bio gets freed */
1267        raid10_find_phys(conf, r10_bio);
1268retry_write:
1269        blocked_rdev = NULL;
1270        rcu_read_lock();
1271        max_sectors = r10_bio->sectors;
1272
1273        for (i = 0;  i < conf->copies; i++) {
1274                int d = r10_bio->devs[i].devnum;
1275                struct md_rdev *rdev = rcu_dereference(conf->mirrors[d].rdev);
1276                struct md_rdev *rrdev = rcu_dereference(
1277                        conf->mirrors[d].replacement);
1278                if (rdev == rrdev)
1279                        rrdev = NULL;
1280                if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
1281                        atomic_inc(&rdev->nr_pending);
1282                        blocked_rdev = rdev;
1283                        break;
1284                }
1285                if (rrdev && unlikely(test_bit(Blocked, &rrdev->flags))) {
1286                        atomic_inc(&rrdev->nr_pending);
1287                        blocked_rdev = rrdev;
1288                        break;
1289                }
1290                if (rrdev && (test_bit(Faulty, &rrdev->flags)
1291                              || test_bit(Unmerged, &rrdev->flags)))
1292                        rrdev = NULL;
1293
1294                r10_bio->devs[i].bio = NULL;
1295                r10_bio->devs[i].repl_bio = NULL;
1296                if (!rdev || test_bit(Faulty, &rdev->flags) ||
1297                    test_bit(Unmerged, &rdev->flags)) {
1298                        set_bit(R10BIO_Degraded, &r10_bio->state);
1299                        continue;
1300                }
1301                if (test_bit(WriteErrorSeen, &rdev->flags)) {
1302                        sector_t first_bad;
1303                        sector_t dev_sector = r10_bio->devs[i].addr;
1304                        int bad_sectors;
1305                        int is_bad;
1306
1307                        is_bad = is_badblock(rdev, dev_sector,
1308                                             max_sectors,
1309                                             &first_bad, &bad_sectors);
1310                        if (is_bad < 0) {
1311                                /* Mustn't write here until the bad block
1312                                 * is acknowledged
1313                                 */
1314                                atomic_inc(&rdev->nr_pending);
1315                                set_bit(BlockedBadBlocks, &rdev->flags);
1316                                blocked_rdev = rdev;
1317                                break;
1318                        }
1319                        if (is_bad && first_bad <= dev_sector) {
1320                                /* Cannot write here at all */
1321                                bad_sectors -= (dev_sector - first_bad);
1322                                if (bad_sectors < max_sectors)
1323                                        /* Mustn't write more than bad_sectors
1324                                         * to other devices yet
1325                                         */
1326                                        max_sectors = bad_sectors;
1327                                /* We don't set R10BIO_Degraded as that
1328                                 * only applies if the disk is missing,
1329                                 * so it might be re-added, and we want to
1330                                 * know to recover this chunk.
1331                                 * In this case the device is here, and the
1332                                 * fact that this chunk is not in-sync is
1333                                 * recorded in the bad block log.
1334                                 */
1335                                continue;
1336                        }
1337                        if (is_bad) {
1338                                int good_sectors = first_bad - dev_sector;
1339                                if (good_sectors < max_sectors)
1340                                        max_sectors = good_sectors;
1341                        }
1342                }
1343                r10_bio->devs[i].bio = bio;
1344                atomic_inc(&rdev->nr_pending);
1345                if (rrdev) {
1346                        r10_bio->devs[i].repl_bio = bio;
1347                        atomic_inc(&rrdev->nr_pending);
1348                }
1349        }
1350        rcu_read_unlock();
1351
1352        if (unlikely(blocked_rdev)) {
1353                /* Have to wait for this device to get unblocked, then retry */
1354                int j;
1355                int d;
1356
1357                for (j = 0; j < i; j++) {
1358                        if (r10_bio->devs[j].bio) {
1359                                d = r10_bio->devs[j].devnum;
1360                                rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1361                        }
1362                        if (r10_bio->devs[j].repl_bio) {
1363                                struct md_rdev *rdev;
1364                                d = r10_bio->devs[j].devnum;
1365                                rdev = conf->mirrors[d].replacement;
1366                                if (!rdev) {
1367                                        /* Race with remove_disk */
1368                                        smp_mb();
1369                                        rdev = conf->mirrors[d].rdev;
1370                                }
1371                                rdev_dec_pending(rdev, mddev);
1372                        }
1373                }
1374                allow_barrier(conf);
1375                md_wait_for_blocked_rdev(blocked_rdev, mddev);
1376                wait_barrier(conf);
1377                goto retry_write;
1378        }
1379
1380        if (max_sectors < r10_bio->sectors) {
1381                /* We are splitting this into multiple parts, so
1382                 * we need to prepare for allocating another r10_bio.
1383                 */
1384                r10_bio->sectors = max_sectors;
1385                spin_lock_irq(&conf->device_lock);
1386                if (bio->bi_phys_segments == 0)
1387                        bio->bi_phys_segments = 2;
1388                else
1389                        bio->bi_phys_segments++;
1390                spin_unlock_irq(&conf->device_lock);
1391        }
1392        sectors_handled = r10_bio->sector + max_sectors - bio->bi_sector;
1393
1394        atomic_set(&r10_bio->remaining, 1);
1395        bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
1396
1397        for (i = 0; i < conf->copies; i++) {
1398                struct bio *mbio;
1399                int d = r10_bio->devs[i].devnum;
1400                if (!r10_bio->devs[i].bio)
1401                        continue;
1402
1403                mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1404                md_trim_bio(mbio, r10_bio->sector - bio->bi_sector,
1405                            max_sectors);
1406                r10_bio->devs[i].bio = mbio;
1407
1408                mbio->bi_sector = (r10_bio->devs[i].addr+
1409                                   choose_data_offset(r10_bio,
1410                                                      conf->mirrors[d].rdev));
1411                mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1412                mbio->bi_end_io = raid10_end_write_request;
1413                mbio->bi_rw = WRITE | do_sync | do_fua;
1414                mbio->bi_private = r10_bio;
1415
1416                atomic_inc(&r10_bio->remaining);
1417                spin_lock_irqsave(&conf->device_lock, flags);
1418                bio_list_add(&conf->pending_bio_list, mbio);
1419                conf->pending_count++;
1420                spin_unlock_irqrestore(&conf->device_lock, flags);
1421                if (!mddev_check_plugged(mddev))
1422                        md_wakeup_thread(mddev->thread);
1423
1424                if (!r10_bio->devs[i].repl_bio)
1425                        continue;
1426
1427                mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1428                md_trim_bio(mbio, r10_bio->sector - bio->bi_sector,
1429                            max_sectors);
1430                r10_bio->devs[i].repl_bio = mbio;
1431
1432                /* We are actively writing to the original device
1433                 * so it cannot disappear, so the replacement cannot
1434                 * become NULL here
1435                 */
1436                mbio->bi_sector = (r10_bio->devs[i].addr +
1437                                   choose_data_offset(
1438                                           r10_bio,
1439                                           conf->mirrors[d].replacement));
1440                mbio->bi_bdev = conf->mirrors[d].replacement->bdev;
1441                mbio->bi_end_io = raid10_end_write_request;
1442                mbio->bi_rw = WRITE | do_sync | do_fua;
1443                mbio->bi_private = r10_bio;
1444
1445                atomic_inc(&r10_bio->remaining);
1446                spin_lock_irqsave(&conf->device_lock, flags);
1447                bio_list_add(&conf->pending_bio_list, mbio);
1448                conf->pending_count++;
1449                spin_unlock_irqrestore(&conf->device_lock, flags);
1450                if (!mddev_check_plugged(mddev))
1451                        md_wakeup_thread(mddev->thread);
1452        }
1453
1454        /* Don't remove the bias on 'remaining' (one_write_done) until
1455         * after checking if we need to go around again.
1456         */
1457
1458        if (sectors_handled < (bio->bi_size >> 9)) {
1459                one_write_done(r10_bio);
1460                /* We need another r10_bio.  It has already been counted
1461                 * in bio->bi_phys_segments.
1462                 */
1463                r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1464
1465                r10_bio->master_bio = bio;
1466                r10_bio->sectors = (bio->bi_size >> 9) - sectors_handled;
1467
1468                r10_bio->mddev = mddev;
1469                r10_bio->sector = bio->bi_sector + sectors_handled;
1470                r10_bio->state = 0;
1471                goto retry_write;
1472        }
1473        one_write_done(r10_bio);
1474
1475        /* In case raid10d snuck in to freeze_array */
1476        wake_up(&conf->wait_barrier);
1477}
1478
1479static void status(struct seq_file *seq, struct mddev *mddev)
1480{
1481        struct r10conf *conf = mddev->private;
1482        int i;
1483
1484        if (conf->geo.near_copies < conf->geo.raid_disks)
1485                seq_printf(seq, " %dK chunks", mddev->chunk_sectors / 2);
1486        if (conf->geo.near_copies > 1)
1487                seq_printf(seq, " %d near-copies", conf->geo.near_copies);
1488        if (conf->geo.far_copies > 1) {
1489                if (conf->geo.far_offset)
1490                        seq_printf(seq, " %d offset-copies", conf->geo.far_copies);
1491                else
1492                        seq_printf(seq, " %d far-copies", conf->geo.far_copies);
1493        }
1494        seq_printf(seq, " [%d/%d] [", conf->geo.raid_disks,
1495                                        conf->geo.raid_disks - mddev->degraded);
1496        for (i = 0; i < conf->geo.raid_disks; i++)
1497                seq_printf(seq, "%s",
1498                              conf->mirrors[i].rdev &&
1499                              test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
1500        seq_printf(seq, "]");
1501}
1502
1503/* check if there are enough drives for
1504 * every block to appear on atleast one.
1505 * Don't consider the device numbered 'ignore'
1506 * as we might be about to remove it.
1507 */
1508static int _enough(struct r10conf *conf, struct geom *geo, int ignore)
1509{
1510        int first = 0;
1511
1512        do {
1513                int n = conf->copies;
1514                int cnt = 0;
1515                int this = first;
1516                while (n--) {
1517                        if (conf->mirrors[this].rdev &&
1518                            this != ignore)
1519                                cnt++;
1520                        this = (this+1) % geo->raid_disks;
1521                }
1522                if (cnt == 0)
1523                        return 0;
1524                first = (first + geo->near_copies) % geo->raid_disks;
1525        } while (first != 0);
1526        return 1;
1527}
1528
1529static int enough(struct r10conf *conf, int ignore)
1530{
1531        return _enough(conf, &conf->geo, ignore) &&
1532                _enough(conf, &conf->prev, ignore);
1533}
1534
1535static void error(struct mddev *mddev, struct md_rdev *rdev)
1536{
1537        char b[BDEVNAME_SIZE];
1538        struct r10conf *conf = mddev->private;
1539
1540        /*
1541         * If it is not operational, then we have already marked it as dead
1542         * else if it is the last working disks, ignore the error, let the
1543         * next level up know.
1544         * else mark the drive as failed
1545         */
1546        if (test_bit(In_sync, &rdev->flags)
1547            && !enough(conf, rdev->raid_disk))
1548                /*
1549                 * Don't fail the drive, just return an IO error.
1550                 */
1551                return;
1552        if (test_and_clear_bit(In_sync, &rdev->flags)) {
1553                unsigned long flags;
1554                spin_lock_irqsave(&conf->device_lock, flags);
1555                mddev->degraded++;
1556                spin_unlock_irqrestore(&conf->device_lock, flags);
1557                /*
1558                 * if recovery is running, make sure it aborts.
1559                 */
1560                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1561        }
1562        set_bit(Blocked, &rdev->flags);
1563        set_bit(Faulty, &rdev->flags);
1564        set_bit(MD_CHANGE_DEVS, &mddev->flags);
1565        printk(KERN_ALERT
1566               "md/raid10:%s: Disk failure on %s, disabling device.\n"
1567               "md/raid10:%s: Operation continuing on %d devices.\n",
1568               mdname(mddev), bdevname(rdev->bdev, b),
1569               mdname(mddev), conf->geo.raid_disks - mddev->degraded);
1570}
1571
1572static void print_conf(struct r10conf *conf)
1573{
1574        int i;
1575        struct raid10_info *tmp;
1576
1577        printk(KERN_DEBUG "RAID10 conf printout:\n");
1578        if (!conf) {
1579                printk(KERN_DEBUG "(!conf)\n");
1580                return;
1581        }
1582        printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->geo.raid_disks - conf->mddev->degraded,
1583                conf->geo.raid_disks);
1584
1585        for (i = 0; i < conf->geo.raid_disks; i++) {
1586                char b[BDEVNAME_SIZE];
1587                tmp = conf->mirrors + i;
1588                if (tmp->rdev)
1589                        printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1590                                i, !test_bit(In_sync, &tmp->rdev->flags),
1591                                !test_bit(Faulty, &tmp->rdev->flags),
1592                                bdevname(tmp->rdev->bdev,b));
1593        }
1594}
1595
1596static void close_sync(struct r10conf *conf)
1597{
1598        wait_barrier(conf);
1599        allow_barrier(conf);
1600
1601        mempool_destroy(conf->r10buf_pool);
1602        conf->r10buf_pool = NULL;
1603}
1604
1605static int raid10_spare_active(struct mddev *mddev)
1606{
1607        int i;
1608        struct r10conf *conf = mddev->private;
1609        struct raid10_info *tmp;
1610        int count = 0;
1611        unsigned long flags;
1612
1613        /*
1614         * Find all non-in_sync disks within the RAID10 configuration
1615         * and mark them in_sync
1616         */
1617        for (i = 0; i < conf->geo.raid_disks; i++) {
1618                tmp = conf->mirrors + i;
1619                if (tmp->replacement
1620                    && tmp->replacement->recovery_offset == MaxSector
1621                    && !test_bit(Faulty, &tmp->replacement->flags)
1622                    && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
1623                        /* Replacement has just become active */
1624                        if (!tmp->rdev
1625                            || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
1626                                count++;
1627                        if (tmp->rdev) {
1628                                /* Replaced device not technically faulty,
1629                                 * but we need to be sure it gets removed
1630                                 * and never re-added.
1631                                 */
1632                                set_bit(Faulty, &tmp->rdev->flags);
1633                                sysfs_notify_dirent_safe(
1634                                        tmp->rdev->sysfs_state);
1635                        }
1636                        sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
1637                } else if (tmp->rdev
1638                           && !test_bit(Faulty, &tmp->rdev->flags)
1639                           && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1640                        count++;
1641                        sysfs_notify_dirent(tmp->rdev->sysfs_state);
1642                }
1643        }
1644        spin_lock_irqsave(&conf->device_lock, flags);
1645        mddev->degraded -= count;
1646        spin_unlock_irqrestore(&conf->device_lock, flags);
1647
1648        print_conf(conf);
1649        return count;
1650}
1651
1652
1653static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
1654{
1655        struct r10conf *conf = mddev->private;
1656        int err = -EEXIST;
1657        int mirror;
1658        int first = 0;
1659        int last = conf->geo.raid_disks - 1;
1660        struct request_queue *q = bdev_get_queue(rdev->bdev);
1661
1662        if (mddev->recovery_cp < MaxSector)
1663                /* only hot-add to in-sync arrays, as recovery is
1664                 * very different from resync
1665                 */
1666                return -EBUSY;
1667        if (rdev->saved_raid_disk < 0 && !_enough(conf, &conf->prev, -1))
1668                return -EINVAL;
1669
1670        if (rdev->raid_disk >= 0)
1671                first = last = rdev->raid_disk;
1672
1673        if (q->merge_bvec_fn) {
1674                set_bit(Unmerged, &rdev->flags);
1675                mddev->merge_check_needed = 1;
1676        }
1677
1678        if (rdev->saved_raid_disk >= first &&
1679            conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1680                mirror = rdev->saved_raid_disk;
1681        else
1682                mirror = first;
1683        for ( ; mirror <= last ; mirror++) {
1684                struct raid10_info *p = &conf->mirrors[mirror];
1685                if (p->recovery_disabled == mddev->recovery_disabled)
1686                        continue;
1687                if (p->rdev) {
1688                        if (!test_bit(WantReplacement, &p->rdev->flags) ||
1689                            p->replacement != NULL)
1690                                continue;
1691                        clear_bit(In_sync, &rdev->flags);
1692                        set_bit(Replacement, &rdev->flags);
1693                        rdev->raid_disk = mirror;
1694                        err = 0;
1695                        disk_stack_limits(mddev->gendisk, rdev->bdev,
1696                                          rdev->data_offset << 9);
1697                        conf->fullsync = 1;
1698                        rcu_assign_pointer(p->replacement, rdev);
1699                        break;
1700                }
1701
1702                disk_stack_limits(mddev->gendisk, rdev->bdev,
1703                                  rdev->data_offset << 9);
1704
1705                p->head_position = 0;
1706                p->recovery_disabled = mddev->recovery_disabled - 1;
1707                rdev->raid_disk = mirror;
1708                err = 0;
1709                if (rdev->saved_raid_disk != mirror)
1710                        conf->fullsync = 1;
1711                rcu_assign_pointer(p->rdev, rdev);
1712                break;
1713        }
1714        if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
1715                /* Some requests might not have seen this new
1716                 * merge_bvec_fn.  We must wait for them to complete
1717                 * before merging the device fully.
1718                 * First we make sure any code which has tested
1719                 * our function has submitted the request, then
1720                 * we wait for all outstanding requests to complete.
1721                 */
1722                synchronize_sched();
1723                raise_barrier(conf, 0);
1724                lower_barrier(conf);
1725                clear_bit(Unmerged, &rdev->flags);
1726        }
1727        md_integrity_add_rdev(rdev, mddev);
1728        print_conf(conf);
1729        return err;
1730}
1731
1732static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
1733{
1734        struct r10conf *conf = mddev->private;
1735        int err = 0;
1736        int number = rdev->raid_disk;
1737        struct md_rdev **rdevp;
1738        struct raid10_info *p = conf->mirrors + number;
1739
1740        print_conf(conf);
1741        if (rdev == p->rdev)
1742                rdevp = &p->rdev;
1743        else if (rdev == p->replacement)
1744                rdevp = &p->replacement;
1745        else
1746                return 0;
1747
1748        if (test_bit(In_sync, &rdev->flags) ||
1749            atomic_read(&rdev->nr_pending)) {
1750                err = -EBUSY;
1751                goto abort;
1752        }
1753        /* Only remove faulty devices if recovery
1754         * is not possible.
1755         */
1756        if (!test_bit(Faulty, &rdev->flags) &&
1757            mddev->recovery_disabled != p->recovery_disabled &&
1758            (!p->replacement || p->replacement == rdev) &&
1759            number < conf->geo.raid_disks &&
1760            enough(conf, -1)) {
1761                err = -EBUSY;
1762                goto abort;
1763        }
1764        *rdevp = NULL;
1765        synchronize_rcu();
1766        if (atomic_read(&rdev->nr_pending)) {
1767                /* lost the race, try later */
1768                err = -EBUSY;
1769                *rdevp = rdev;
1770                goto abort;
1771        } else if (p->replacement) {
1772                /* We must have just cleared 'rdev' */
1773                p->rdev = p->replacement;
1774                clear_bit(Replacement, &p->replacement->flags);
1775                smp_mb(); /* Make sure other CPUs may see both as identical
1776                           * but will never see neither -- if they are careful.
1777                           */
1778                p->replacement = NULL;
1779                clear_bit(WantReplacement, &rdev->flags);
1780        } else
1781                /* We might have just remove the Replacement as faulty
1782                 * Clear the flag just in case
1783                 */
1784                clear_bit(WantReplacement, &rdev->flags);
1785
1786        err = md_integrity_register(mddev);
1787
1788abort:
1789
1790        print_conf(conf);
1791        return err;
1792}
1793
1794
1795static void end_sync_read(struct bio *bio, int error)
1796{
1797        struct r10bio *r10_bio = bio->bi_private;
1798        struct r10conf *conf = r10_bio->mddev->private;
1799        int d;
1800
1801        if (bio == r10_bio->master_bio) {
1802                /* this is a reshape read */
1803                d = r10_bio->read_slot; /* really the read dev */
1804        } else
1805                d = find_bio_disk(conf, r10_bio, bio, NULL, NULL);
1806
1807        if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1808                set_bit(R10BIO_Uptodate, &r10_bio->state);
1809        else
1810                /* The write handler will notice the lack of
1811                 * R10BIO_Uptodate and record any errors etc
1812                 */
1813                atomic_add(r10_bio->sectors,
1814                           &conf->mirrors[d].rdev->corrected_errors);
1815
1816        /* for reconstruct, we always reschedule after a read.
1817         * for resync, only after all reads
1818         */
1819        rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1820        if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1821            atomic_dec_and_test(&r10_bio->remaining)) {
1822                /* we have read all the blocks,
1823                 * do the comparison in process context in raid10d
1824                 */
1825                reschedule_retry(r10_bio);
1826        }
1827}
1828
1829static void end_sync_request(struct r10bio *r10_bio)
1830{
1831        struct mddev *mddev = r10_bio->mddev;
1832
1833        while (atomic_dec_and_test(&r10_bio->remaining)) {
1834                if (r10_bio->master_bio == NULL) {
1835                        /* the primary of several recovery bios */
1836                        sector_t s = r10_bio->sectors;
1837                        if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1838                            test_bit(R10BIO_WriteError, &r10_bio->state))
1839                                reschedule_retry(r10_bio);
1840                        else
1841                                put_buf(r10_bio);
1842                        md_done_sync(mddev, s, 1);
1843                        break;
1844                } else {
1845                        struct r10bio *r10_bio2 = (struct r10bio *)r10_bio->master_bio;
1846                        if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1847                            test_bit(R10BIO_WriteError, &r10_bio->state))
1848                                reschedule_retry(r10_bio);
1849                        else
1850                                put_buf(r10_bio);
1851                        r10_bio = r10_bio2;
1852                }
1853        }
1854}
1855
1856static void end_sync_write(struct bio *bio, int error)
1857{
1858        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1859        struct r10bio *r10_bio = bio->bi_private;
1860        struct mddev *mddev = r10_bio->mddev;
1861        struct r10conf *conf = mddev->private;
1862        int d;
1863        sector_t first_bad;
1864        int bad_sectors;
1865        int slot;
1866        int repl;
1867        struct md_rdev *rdev = NULL;
1868
1869        d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
1870        if (repl)
1871                rdev = conf->mirrors[d].replacement;
1872        else
1873                rdev = conf->mirrors[d].rdev;
1874
1875        if (!uptodate) {
1876                if (repl)
1877                        md_error(mddev, rdev);
1878                else {
1879                        set_bit(WriteErrorSeen, &rdev->flags);
1880                        if (!test_and_set_bit(WantReplacement, &rdev->flags))
1881                                set_bit(MD_RECOVERY_NEEDED,
1882                                        &rdev->mddev->recovery);
1883                        set_bit(R10BIO_WriteError, &r10_bio->state);
1884                }
1885        } else if (is_badblock(rdev,
1886                             r10_bio->devs[slot].addr,
1887                             r10_bio->sectors,
1888                             &first_bad, &bad_sectors))
1889                set_bit(R10BIO_MadeGood, &r10_bio->state);
1890
1891        rdev_dec_pending(rdev, mddev);
1892
1893        end_sync_request(r10_bio);
1894}
1895
1896/*
1897 * Note: sync and recover and handled very differently for raid10
1898 * This code is for resync.
1899 * For resync, we read through virtual addresses and read all blocks.
1900 * If there is any error, we schedule a write.  The lowest numbered
1901 * drive is authoritative.
1902 * However requests come for physical address, so we need to map.
1903 * For every physical address there are raid_disks/copies virtual addresses,
1904 * which is always are least one, but is not necessarly an integer.
1905 * This means that a physical address can span multiple chunks, so we may
1906 * have to submit multiple io requests for a single sync request.
1907 */
1908/*
1909 * We check if all blocks are in-sync and only write to blocks that
1910 * aren't in sync
1911 */
1912static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
1913{
1914        struct r10conf *conf = mddev->private;
1915        int i, first;
1916        struct bio *tbio, *fbio;
1917        int vcnt;
1918
1919        atomic_set(&r10_bio->remaining, 1);
1920
1921        /* find the first device with a block */
1922        for (i=0; i<conf->copies; i++)
1923                if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
1924                        break;
1925
1926        if (i == conf->copies)
1927                goto done;
1928
1929        first = i;
1930        fbio = r10_bio->devs[i].bio;
1931
1932        vcnt = (r10_bio->sectors + (PAGE_SIZE >> 9) - 1) >> (PAGE_SHIFT - 9);
1933        /* now find blocks with errors */
1934        for (i=0 ; i < conf->copies ; i++) {
1935                int  j, d;
1936
1937                tbio = r10_bio->devs[i].bio;
1938
1939                if (tbio->bi_end_io != end_sync_read)
1940                        continue;
1941                if (i == first)
1942                        continue;
1943                if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
1944                        /* We know that the bi_io_vec layout is the same for
1945                         * both 'first' and 'i', so we just compare them.
1946                         * All vec entries are PAGE_SIZE;
1947                         */
1948                        for (j = 0; j < vcnt; j++)
1949                                if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
1950                                           page_address(tbio->bi_io_vec[j].bv_page),
1951                                           fbio->bi_io_vec[j].bv_len))
1952                                        break;
1953                        if (j == vcnt)
1954                                continue;
1955                        mddev->resync_mismatches += r10_bio->sectors;
1956                        if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
1957                                /* Don't fix anything. */
1958                                continue;
1959                }
1960                /* Ok, we need to write this bio, either to correct an
1961                 * inconsistency or to correct an unreadable block.
1962                 * First we need to fixup bv_offset, bv_len and
1963                 * bi_vecs, as the read request might have corrupted these
1964                 */
1965                tbio->bi_vcnt = vcnt;
1966                tbio->bi_size = r10_bio->sectors << 9;
1967                tbio->bi_idx = 0;
1968                tbio->bi_phys_segments = 0;
1969                tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1970                tbio->bi_flags |= 1 << BIO_UPTODATE;
1971                tbio->bi_next = NULL;
1972                tbio->bi_rw = WRITE;
1973                tbio->bi_private = r10_bio;
1974                tbio->bi_sector = r10_bio->devs[i].addr;
1975
1976                for (j=0; j < vcnt ; j++) {
1977                        tbio->bi_io_vec[j].bv_offset = 0;
1978                        tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
1979
1980                        memcpy(page_address(tbio->bi_io_vec[j].bv_page),
1981                               page_address(fbio->bi_io_vec[j].bv_page),
1982                               PAGE_SIZE);
1983                }
1984                tbio->bi_end_io = end_sync_write;
1985
1986                d = r10_bio->devs[i].devnum;
1987                atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1988                atomic_inc(&r10_bio->remaining);
1989                md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
1990
1991                tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
1992                tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1993                generic_make_request(tbio);
1994        }
1995
1996        /* Now write out to any replacement devices
1997         * that are active
1998         */
1999        for (i = 0; i < conf->copies; i++) {
2000                int j, d;
2001
2002                tbio = r10_bio->devs[i].repl_bio;
2003                if (!tbio || !tbio->bi_end_io)
2004                        continue;
2005                if (r10_bio->devs[i].bio->bi_end_io != end_sync_write
2006                    && r10_bio->devs[i].bio != fbio)
2007                        for (j = 0; j < vcnt; j++)
2008                                memcpy(page_address(tbio->bi_io_vec[j].bv_page),
2009                                       page_address(fbio->bi_io_vec[j].bv_page),
2010                                       PAGE_SIZE);
2011                d = r10_bio->devs[i].devnum;
2012                atomic_inc(&r10_bio->remaining);
2013                md_sync_acct(conf->mirrors[d].replacement->bdev,
2014                             tbio->bi_size >> 9);
2015                generic_make_request(tbio);
2016        }
2017
2018done:
2019        if (atomic_dec_and_test(&r10_bio->remaining)) {
2020                md_done_sync(mddev, r10_bio->sectors, 1);
2021                put_buf(r10_bio);
2022        }
2023}
2024
2025/*
2026 * Now for the recovery code.
2027 * Recovery happens across physical sectors.
2028 * We recover all non-is_sync drives by finding the virtual address of
2029 * each, and then choose a working drive that also has that virt address.
2030 * There is a separate r10_bio for each non-in_sync drive.
2031 * Only the first two slots are in use. The first for reading,
2032 * The second for writing.
2033 *
2034 */
2035static void fix_recovery_read_error(struct r10bio *r10_bio)
2036{
2037        /* We got a read error during recovery.
2038         * We repeat the read in smaller page-sized sections.
2039         * If a read succeeds, write it to the new device or record
2040         * a bad block if we cannot.
2041         * If a read fails, record a bad block on both old and
2042         * new devices.
2043         */
2044        struct mddev *mddev = r10_bio->mddev;
2045        struct r10conf *conf = mddev->private;
2046        struct bio *bio = r10_bio->devs[0].bio;
2047        sector_t sect = 0;
2048        int sectors = r10_bio->sectors;
2049        int idx = 0;
2050        int dr = r10_bio->devs[0].devnum;
2051        int dw = r10_bio->devs[1].devnum;
2052
2053        while (sectors) {
2054                int s = sectors;
2055                struct md_rdev *rdev;
2056                sector_t addr;
2057                int ok;
2058
2059                if (s > (PAGE_SIZE>>9))
2060                        s = PAGE_SIZE >> 9;
2061
2062                rdev = conf->mirrors[dr].rdev;
2063                addr = r10_bio->devs[0].addr + sect,
2064                ok = sync_page_io(rdev,
2065                                  addr,
2066                                  s << 9,
2067                                  bio->bi_io_vec[idx].bv_page,
2068                                  READ, false);
2069                if (ok) {
2070                        rdev = conf->mirrors[dw].rdev;
2071                        addr = r10_bio->devs[1].addr + sect;
2072                        ok = sync_page_io(rdev,
2073                                          addr,
2074                                          s << 9,
2075                                          bio->bi_io_vec[idx].bv_page,
2076                                          WRITE, false);
2077                        if (!ok) {
2078                                set_bit(WriteErrorSeen, &rdev->flags);
2079                                if (!test_and_set_bit(WantReplacement,
2080                                                      &rdev->flags))
2081                                        set_bit(MD_RECOVERY_NEEDED,
2082                                                &rdev->mddev->recovery);
2083                        }
2084                }
2085                if (!ok) {
2086                        /* We don't worry if we cannot set a bad block -
2087                         * it really is bad so there is no loss in not
2088                         * recording it yet
2089                         */
2090                        rdev_set_badblocks(rdev, addr, s, 0);
2091
2092                        if (rdev != conf->mirrors[dw].rdev) {
2093                                /* need bad block on destination too */
2094                                struct md_rdev *rdev2 = conf->mirrors[dw].rdev;
2095                                addr = r10_bio->devs[1].addr + sect;
2096                                ok = rdev_set_badblocks(rdev2, addr, s, 0);
2097                                if (!ok) {
2098                                        /* just abort the recovery */
2099                                        printk(KERN_NOTICE
2100                                               "md/raid10:%s: recovery aborted"
2101                                               " due to read error\n",
2102                                               mdname(mddev));
2103
2104                                        conf->mirrors[dw].recovery_disabled
2105                                                = mddev->recovery_disabled;
2106                                        set_bit(MD_RECOVERY_INTR,
2107                                                &mddev->recovery);
2108                                        break;
2109                                }
2110                        }
2111                }
2112
2113                sectors -= s;
2114                sect += s;
2115                idx++;
2116        }
2117}
2118
2119static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio)
2120{
2121        struct r10conf *conf = mddev->private;
2122        int d;
2123        struct bio *wbio, *wbio2;
2124
2125        if (!test_bit(R10BIO_Uptodate, &r10_bio->state)) {
2126                fix_recovery_read_error(r10_bio);
2127                end_sync_request(r10_bio);
2128                return;
2129        }
2130
2131        /*
2132         * share the pages with the first bio
2133         * and submit the write request
2134         */
2135        d = r10_bio->devs[1].devnum;
2136        wbio = r10_bio->devs[1].bio;
2137        wbio2 = r10_bio->devs[1].repl_bio;
2138        if (wbio->bi_end_io) {
2139                atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2140                md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
2141                generic_make_request(wbio);
2142        }
2143        if (wbio2 && wbio2->bi_end_io) {
2144                atomic_inc(&conf->mirrors[d].replacement->nr_pending);
2145                md_sync_acct(conf->mirrors[d].replacement->bdev,
2146                             wbio2->bi_size >> 9);
2147                generic_make_request(wbio2);
2148        }
2149}
2150
2151
2152/*
2153 * Used by fix_read_error() to decay the per rdev read_errors.
2154 * We halve the read error count for every hour that has elapsed
2155 * since the last recorded read error.
2156 *
2157 */
2158static void check_decay_read_errors(struct mddev *mddev, struct md_rdev *rdev)
2159{
2160        struct timespec cur_time_mon;
2161        unsigned long hours_since_last;
2162        unsigned int read_errors = atomic_read(&rdev->read_errors);
2163
2164        ktime_get_ts(&cur_time_mon);
2165
2166        if (rdev->last_read_error.tv_sec == 0 &&
2167            rdev->last_read_error.tv_nsec == 0) {
2168                /* first time we've seen a read error */
2169                rdev->last_read_error = cur_time_mon;
2170                return;
2171        }
2172
2173        hours_since_last = (cur_time_mon.tv_sec -
2174                            rdev->last_read_error.tv_sec) / 3600;
2175
2176        rdev->last_read_error = cur_time_mon;
2177
2178        /*
2179         * if hours_since_last is > the number of bits in read_errors
2180         * just set read errors to 0. We do this to avoid
2181         * overflowing the shift of read_errors by hours_since_last.
2182         */
2183        if (hours_since_last >= 8 * sizeof(read_errors))
2184                atomic_set(&rdev->read_errors, 0);
2185        else
2186                atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
2187}
2188
2189static int r10_sync_page_io(struct md_rdev *rdev, sector_t sector,
2190                            int sectors, struct page *page, int rw)
2191{
2192        sector_t first_bad;
2193        int bad_sectors;
2194
2195        if (is_badblock(rdev, sector, sectors, &first_bad, &bad_sectors)
2196            && (rw == READ || test_bit(WriteErrorSeen, &rdev->flags)))
2197                return -1;
2198        if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
2199                /* success */
2200                return 1;
2201        if (rw == WRITE) {
2202                set_bit(WriteErrorSeen, &rdev->flags);
2203                if (!test_and_set_bit(WantReplacement, &rdev->flags))
2204                        set_bit(MD_RECOVERY_NEEDED,
2205                                &rdev->mddev->recovery);
2206        }
2207        /* need to record an error - either for the block or the device */
2208        if (!rdev_set_badblocks(rdev, sector, sectors, 0))
2209                md_error(rdev->mddev, rdev);
2210        return 0;
2211}
2212
2213/*
2214 * This is a kernel thread which:
2215 *
2216 *      1.      Retries failed read operations on working mirrors.
2217 *      2.      Updates the raid superblock when problems encounter.
2218 *      3.      Performs writes following reads for array synchronising.
2219 */
2220
2221static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10bio *r10_bio)
2222{
2223        int sect = 0; /* Offset from r10_bio->sector */
2224        int sectors = r10_bio->sectors;
2225        struct md_rdev*rdev;
2226        int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
2227        int d = r10_bio->devs[r10_bio->read_slot].devnum;
2228
2229        /* still own a reference to this rdev, so it cannot
2230         * have been cleared recently.
2231         */
2232        rdev = conf->mirrors[d].rdev;
2233
2234        if (test_bit(Faulty, &rdev->flags))
2235                /* drive has already been failed, just ignore any
2236                   more fix_read_error() attempts */
2237                return;
2238
2239        check_decay_read_errors(mddev, rdev);
2240        atomic_inc(&rdev->read_errors);
2241        if (atomic_read(&rdev->read_errors) > max_read_errors) {
2242                char b[BDEVNAME_SIZE];
2243                bdevname(rdev->bdev, b);
2244
2245                printk(KERN_NOTICE
2246                       "md/raid10:%s: %s: Raid device exceeded "
2247                       "read_error threshold [cur %d:max %d]\n",
2248                       mdname(mddev), b,
2249                       atomic_read(&rdev->read_errors), max_read_errors);
2250                printk(KERN_NOTICE
2251                       "md/raid10:%s: %s: Failing raid device\n",
2252                       mdname(mddev), b);
2253                md_error(mddev, conf->mirrors[d].rdev);
2254                r10_bio->devs[r10_bio->read_slot].bio = IO_BLOCKED;
2255                return;
2256        }
2257
2258        while(sectors) {
2259                int s = sectors;
2260                int sl = r10_bio->read_slot;
2261                int success = 0;
2262                int start;
2263
2264                if (s > (PAGE_SIZE>>9))
2265                        s = PAGE_SIZE >> 9;
2266
2267                rcu_read_lock();
2268                do {
2269                        sector_t first_bad;
2270                        int bad_sectors;
2271
2272                        d = r10_bio->devs[sl].devnum;
2273                        rdev = rcu_dereference(conf->mirrors[d].rdev);
2274                        if (rdev &&
2275                            !test_bit(Unmerged, &rdev->flags) &&
2276                            test_bit(In_sync, &rdev->flags) &&
2277                            is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
2278                                        &first_bad, &bad_sectors) == 0) {
2279                                atomic_inc(&rdev->nr_pending);
2280                                rcu_read_unlock();
2281                                success = sync_page_io(rdev,
2282                                                       r10_bio->devs[sl].addr +
2283                                                       sect,
2284                                                       s<<9,
2285                                                       conf->tmppage, READ, false);
2286                                rdev_dec_pending(rdev, mddev);
2287                                rcu_read_lock();
2288                                if (success)
2289                                        break;
2290                        }
2291                        sl++;
2292                        if (sl == conf->copies)
2293                                sl = 0;
2294                } while (!success && sl != r10_bio->read_slot);
2295                rcu_read_unlock();
2296
2297                if (!success) {
2298                        /* Cannot read from anywhere, just mark the block
2299                         * as bad on the first device to discourage future
2300                         * reads.
2301                         */
2302                        int dn = r10_bio->devs[r10_bio->read_slot].devnum;
2303                        rdev = conf->mirrors[dn].rdev;
2304
2305                        if (!rdev_set_badblocks(
2306                                    rdev,
2307                                    r10_bio->devs[r10_bio->read_slot].addr
2308                                    + sect,
2309                                    s, 0)) {
2310                                md_error(mddev, rdev);
2311                                r10_bio->devs[r10_bio->read_slot].bio
2312                                        = IO_BLOCKED;
2313                        }
2314                        break;
2315                }
2316
2317                start = sl;
2318                /* write it back and re-read */
2319                rcu_read_lock();
2320                while (sl != r10_bio->read_slot) {
2321                        char b[BDEVNAME_SIZE];
2322
2323                        if (sl==0)
2324                                sl = conf->copies;
2325                        sl--;
2326                        d = r10_bio->devs[sl].devnum;
2327                        rdev = rcu_dereference(conf->mirrors[d].rdev);
2328                        if (!rdev ||
2329                            test_bit(Unmerged, &rdev->flags) ||
2330                            !test_bit(In_sync, &rdev->flags))
2331                                continue;
2332
2333                        atomic_inc(&rdev->nr_pending);
2334                        rcu_read_unlock();
2335                        if (r10_sync_page_io(rdev,
2336                                             r10_bio->devs[sl].addr +
2337                                             sect,
2338                                             s, conf->tmppage, WRITE)
2339                            == 0) {
2340                                /* Well, this device is dead */
2341                                printk(KERN_NOTICE
2342                                       "md/raid10:%s: read correction "
2343                                       "write failed"
2344                                       " (%d sectors at %llu on %s)\n",
2345                                       mdname(mddev), s,
2346                                       (unsigned long long)(
2347                                               sect +
2348                                               choose_data_offset(r10_bio,
2349                                                                  rdev)),
2350                                       bdevname(rdev->bdev, b));
2351                                printk(KERN_NOTICE "md/raid10:%s: %s: failing "
2352                                       "drive\n",
2353                                       mdname(mddev),
2354                                       bdevname(rdev->bdev, b));
2355                        }
2356                        rdev_dec_pending(rdev, mddev);
2357                        rcu_read_lock();
2358                }
2359                sl = start;
2360                while (sl != r10_bio->read_slot) {
2361                        char b[BDEVNAME_SIZE];
2362
2363                        if (sl==0)
2364                                sl = conf->copies;
2365                        sl--;
2366                        d = r10_bio->devs[sl].devnum;
2367                        rdev = rcu_dereference(conf->mirrors[d].rdev);
2368                        if (!rdev ||
2369                            !test_bit(In_sync, &rdev->flags))
2370                                continue;
2371
2372                        atomic_inc(&rdev->nr_pending);
2373                        rcu_read_unlock();
2374                        switch (r10_sync_page_io(rdev,
2375                                             r10_bio->devs[sl].addr +
2376                                             sect,
2377                                             s, conf->tmppage,
2378                                                 READ)) {
2379                        case 0:
2380                                /* Well, this device is dead */
2381                                printk(KERN_NOTICE
2382                                       "md/raid10:%s: unable to read back "
2383                                       "corrected sectors"
2384                                       " (%d sectors at %llu on %s)\n",
2385                                       mdname(mddev), s,
2386                                       (unsigned long long)(
2387                                               sect +
2388                                               choose_data_offset(r10_bio, rdev)),
2389                                       bdevname(rdev->bdev, b));
2390                                printk(KERN_NOTICE "md/raid10:%s: %s: failing "
2391                                       "drive\n",
2392                                       mdname(mddev),
2393                                       bdevname(rdev->bdev, b));
2394                                break;
2395                        case 1:
2396                                printk(KERN_INFO
2397                                       "md/raid10:%s: read error corrected"
2398                                       " (%d sectors at %llu on %s)\n",
2399                                       mdname(mddev), s,
2400                                       (unsigned long long)(
2401                                               sect +
2402                                               choose_data_offset(r10_bio, rdev)),
2403                                       bdevname(rdev->bdev, b));
2404                                atomic_add(s, &rdev->corrected_errors);
2405                        }
2406
2407                        rdev_dec_pending(rdev, mddev);
2408                        rcu_read_lock();
2409                }
2410                rcu_read_unlock();
2411
2412                sectors -= s;
2413                sect += s;
2414        }
2415}
2416
2417static void bi_complete(struct bio *bio, int error)
2418{
2419        complete((struct completion *)bio->bi_private);
2420}
2421
2422static int submit_bio_wait(int rw, struct bio *bio)
2423{
2424        struct completion event;
2425        rw |= REQ_SYNC;
2426
2427        init_completion(&event);
2428        bio->bi_private = &event;
2429        bio->bi_end_io = bi_complete;
2430        submit_bio(rw, bio);
2431        wait_for_completion(&event);
2432
2433        return test_bit(BIO_UPTODATE, &bio->bi_flags);
2434}
2435
2436static int narrow_write_error(struct r10bio *r10_bio, int i)
2437{
2438        struct bio *bio = r10_bio->master_bio;
2439        struct mddev *mddev = r10_bio->mddev;
2440        struct r10conf *conf = mddev->private;
2441        struct md_rdev *rdev = conf->mirrors[r10_bio->devs[i].devnum].rdev;
2442        /* bio has the data to be written to slot 'i' where
2443         * we just recently had a write error.
2444         * We repeatedly clone the bio and trim down to one block,
2445         * then try the write.  Where the write fails we record
2446         * a bad block.
2447         * It is conceivable that the bio doesn't exactly align with
2448         * blocks.  We must handle this.
2449         *
2450         * We currently own a reference to the rdev.
2451         */
2452
2453        int block_sectors;
2454        sector_t sector;
2455        int sectors;
2456        int sect_to_write = r10_bio->sectors;
2457        int ok = 1;
2458
2459        if (rdev->badblocks.shift < 0)
2460                return 0;
2461
2462        block_sectors = 1 << rdev->badblocks.shift;
2463        sector = r10_bio->sector;
2464        sectors = ((r10_bio->sector + block_sectors)
2465                   & ~(sector_t)(block_sectors - 1))
2466                - sector;
2467
2468        while (sect_to_write) {
2469                struct bio *wbio;
2470                if (sectors > sect_to_write)
2471                        sectors = sect_to_write;
2472                /* Write at 'sector' for 'sectors' */
2473                wbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
2474                md_trim_bio(wbio, sector - bio->bi_sector, sectors);
2475                wbio->bi_sector = (r10_bio->devs[i].addr+
2476                                   choose_data_offset(r10_bio, rdev) +
2477                                   (sector - r10_bio->sector));
2478                wbio->bi_bdev = rdev->bdev;
2479                if (submit_bio_wait(WRITE, wbio) == 0)
2480                        /* Failure! */
2481                        ok = rdev_set_badblocks(rdev, sector,
2482                                                sectors, 0)
2483                                && ok;
2484
2485                bio_put(wbio);
2486                sect_to_write -= sectors;
2487                sector += sectors;
2488                sectors = block_sectors;
2489        }
2490        return ok;
2491}
2492
2493static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
2494{
2495        int slot = r10_bio->read_slot;
2496        struct bio *bio;
2497        struct r10conf *conf = mddev->private;
2498        struct md_rdev *rdev = r10_bio->devs[slot].rdev;
2499        char b[BDEVNAME_SIZE];
2500        unsigned long do_sync;
2501        int max_sectors;
2502
2503        /* we got a read error. Maybe the drive is bad.  Maybe just
2504         * the block and we can fix it.
2505         * We freeze all other IO, and try reading the block from
2506         * other devices.  When we find one, we re-write
2507         * and check it that fixes the read error.
2508         * This is all done synchronously while the array is
2509         * frozen.
2510         */
2511        bio = r10_bio->devs[slot].bio;
2512        bdevname(bio->bi_bdev, b);
2513        bio_put(bio);
2514        r10_bio->devs[slot].bio = NULL;
2515
2516        if (mddev->ro == 0) {
2517                freeze_array(conf);
2518                fix_read_error(conf, mddev, r10_bio);
2519                unfreeze_array(conf);
2520        } else
2521                r10_bio->devs[slot].bio = IO_BLOCKED;
2522
2523        rdev_dec_pending(rdev, mddev);
2524
2525read_more:
2526        rdev = read_balance(conf, r10_bio, &max_sectors);
2527        if (rdev == NULL) {
2528                printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
2529                       " read error for block %llu\n",
2530                       mdname(mddev), b,
2531                       (unsigned long long)r10_bio->sector);
2532                raid_end_bio_io(r10_bio);
2533                return;
2534        }
2535
2536        do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
2537        slot = r10_bio->read_slot;
2538        printk_ratelimited(
2539                KERN_ERR
2540                "md/raid10:%s: %s: redirecting "
2541                "sector %llu to another mirror\n",
2542                mdname(mddev),
2543                bdevname(rdev->bdev, b),
2544                (unsigned long long)r10_bio->sector);
2545        bio = bio_clone_mddev(r10_bio->master_bio,
2546                              GFP_NOIO, mddev);
2547        md_trim_bio(bio,
2548                    r10_bio->sector - bio->bi_sector,
2549                    max_sectors);
2550        r10_bio->devs[slot].bio = bio;
2551        r10_bio->devs[slot].rdev = rdev;
2552        bio->bi_sector = r10_bio->devs[slot].addr
2553                + choose_data_offset(r10_bio, rdev);
2554        bio->bi_bdev = rdev->bdev;
2555        bio->bi_rw = READ | do_sync;
2556        bio->bi_private = r10_bio;
2557        bio->bi_end_io = raid10_end_read_request;
2558        if (max_sectors < r10_bio->sectors) {
2559                /* Drat - have to split this up more */
2560                struct bio *mbio = r10_bio->master_bio;
2561                int sectors_handled =
2562                        r10_bio->sector + max_sectors
2563                        - mbio->bi_sector;
2564                r10_bio->sectors = max_sectors;
2565                spin_lock_irq(&conf->device_lock);
2566                if (mbio->bi_phys_segments == 0)
2567                        mbio->bi_phys_segments = 2;
2568                else
2569                        mbio->bi_phys_segments++;
2570                spin_unlock_irq(&conf->device_lock);
2571                generic_make_request(bio);
2572
2573                r10_bio = mempool_alloc(conf->r10bio_pool,
2574                                        GFP_NOIO);
2575                r10_bio->master_bio = mbio;
2576                r10_bio->sectors = (mbio->bi_size >> 9)
2577                        - sectors_handled;
2578                r10_bio->state = 0;
2579                set_bit(R10BIO_ReadError,
2580                        &r10_bio->state);
2581                r10_bio->mddev = mddev;
2582                r10_bio->sector = mbio->bi_sector
2583                        + sectors_handled;
2584
2585                goto read_more;
2586        } else
2587                generic_make_request(bio);
2588}
2589
2590static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
2591{
2592        /* Some sort of write request has finished and it
2593         * succeeded in writing where we thought there was a
2594         * bad block.  So forget the bad block.
2595         * Or possibly if failed and we need to record
2596         * a bad block.
2597         */
2598        int m;
2599        struct md_rdev *rdev;
2600
2601        if (test_bit(R10BIO_IsSync, &r10_bio->state) ||
2602            test_bit(R10BIO_IsRecover, &r10_bio->state)) {
2603                for (m = 0; m < conf->copies; m++) {
2604                        int dev = r10_bio->devs[m].devnum;
2605                        rdev = conf->mirrors[dev].rdev;
2606                        if (r10_bio->devs[m].bio == NULL)
2607                                continue;
2608                        if (test_bit(BIO_UPTODATE,
2609                                     &r10_bio->devs[m].bio->bi_flags)) {
2610                                rdev_clear_badblocks(
2611                                        rdev,
2612                                        r10_bio->devs[m].addr,
2613                                        r10_bio->sectors, 0);
2614                        } else {
2615                                if (!rdev_set_badblocks(
2616                                            rdev,
2617                                            r10_bio->devs[m].addr,
2618                                            r10_bio->sectors, 0))
2619                                        md_error(conf->mddev, rdev);
2620                        }
2621                        rdev = conf->mirrors[dev].replacement;
2622                        if (r10_bio->devs[m].repl_bio == NULL)
2623                                continue;
2624                        if (test_bit(BIO_UPTODATE,
2625                                     &r10_bio->devs[m].repl_bio->bi_flags)) {
2626                                rdev_clear_badblocks(
2627                                        rdev,
2628                                        r10_bio->devs[m].addr,
2629                                        r10_bio->sectors, 0);
2630                        } else {
2631                                if (!rdev_set_badblocks(
2632                                            rdev,
2633                                            r10_bio->devs[m].addr,
2634                                            r10_bio->sectors, 0))
2635                                        md_error(conf->mddev, rdev);
2636                        }
2637                }
2638                put_buf(r10_bio);
2639        } else {
2640                for (m = 0; m < conf->copies; m++) {
2641                        int dev = r10_bio->devs[m].devnum;
2642                        struct bio *bio = r10_bio->devs[m].bio;
2643                        rdev = conf->mirrors[dev].rdev;
2644                        if (bio == IO_MADE_GOOD) {
2645                                rdev_clear_badblocks(
2646                                        rdev,
2647                                        r10_bio->devs[m].addr,
2648                                        r10_bio->sectors, 0);
2649                                rdev_dec_pending(rdev, conf->mddev);
2650                        } else if (bio != NULL &&
2651                                   !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
2652                                if (!narrow_write_error(r10_bio, m)) {
2653                                        md_error(conf->mddev, rdev);
2654                                        set_bit(R10BIO_Degraded,
2655                                                &r10_bio->state);
2656                                }
2657                                rdev_dec_pending(rdev, conf->mddev);
2658                        }
2659                        bio = r10_bio->devs[m].repl_bio;
2660                        rdev = conf->mirrors[dev].replacement;
2661                        if (rdev && bio == IO_MADE_GOOD) {
2662                                rdev_clear_badblocks(
2663                                        rdev,
2664                                        r10_bio->devs[m].addr,
2665                                        r10_bio->sectors, 0);
2666                                rdev_dec_pending(rdev, conf->mddev);
2667                        }
2668                }
2669                if (test_bit(R10BIO_WriteError,
2670                             &r10_bio->state))
2671                        close_write(r10_bio);
2672                raid_end_bio_io(r10_bio);
2673        }
2674}
2675
2676static void raid10d(struct mddev *mddev)
2677{
2678        struct r10bio *r10_bio;
2679        unsigned long flags;
2680        struct r10conf *conf = mddev->private;
2681        struct list_head *head = &conf->retry_list;
2682        struct blk_plug plug;
2683
2684        md_check_recovery(mddev);
2685
2686        blk_start_plug(&plug);
2687        for (;;) {
2688
2689                flush_pending_writes(conf);
2690
2691                spin_lock_irqsave(&conf->device_lock, flags);
2692                if (list_empty(head)) {
2693                        spin_unlock_irqrestore(&conf->device_lock, flags);
2694                        break;
2695                }
2696                r10_bio = list_entry(head->prev, struct r10bio, retry_list);
2697                list_del(head->prev);
2698                conf->nr_queued--;
2699                spin_unlock_irqrestore(&conf->device_lock, flags);
2700
2701                mddev = r10_bio->mddev;
2702                conf = mddev->private;
2703                if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
2704                    test_bit(R10BIO_WriteError, &r10_bio->state))
2705                        handle_write_completed(conf, r10_bio);
2706                else if (test_bit(R10BIO_IsReshape, &r10_bio->state))
2707                        reshape_request_write(mddev, r10_bio);
2708                else if (test_bit(R10BIO_IsSync, &r10_bio->state))
2709                        sync_request_write(mddev, r10_bio);
2710                else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
2711                        recovery_request_write(mddev, r10_bio);
2712                else if (test_bit(R10BIO_ReadError, &r10_bio->state))
2713                        handle_read_error(mddev, r10_bio);
2714                else {
2715                        /* just a partial read to be scheduled from a
2716                         * separate context
2717                         */
2718                        int slot = r10_bio->read_slot;
2719                        generic_make_request(r10_bio->devs[slot].bio);
2720                }
2721
2722                cond_resched();
2723                if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
2724                        md_check_recovery(mddev);
2725        }
2726        blk_finish_plug(&plug);
2727}
2728
2729
2730static int init_resync(struct r10conf *conf)
2731{
2732        int buffs;
2733        int i;
2734
2735        buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
2736        BUG_ON(conf->r10buf_pool);
2737        conf->have_replacement = 0;
2738        for (i = 0; i < conf->geo.raid_disks; i++)
2739                if (conf->mirrors[i].replacement)
2740                        conf->have_replacement = 1;
2741        conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
2742        if (!conf->r10buf_pool)
2743                return -ENOMEM;
2744        conf->next_resync = 0;
2745        return 0;
2746}
2747
2748/*
2749 * perform a "sync" on one "block"
2750 *
2751 * We need to make sure that no normal I/O request - particularly write
2752 * requests - conflict with active sync requests.
2753 *
2754 * This is achieved by tracking pending requests and a 'barrier' concept
2755 * that can be installed to exclude normal IO requests.
2756 *
2757 * Resync and recovery are handled very differently.
2758 * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
2759 *
2760 * For resync, we iterate over virtual addresses, read all copies,
2761 * and update if there are differences.  If only one copy is live,
2762 * skip it.
2763 * For recovery, we iterate over physical addresses, read a good
2764 * value for each non-in_sync drive, and over-write.
2765 *
2766 * So, for recovery we may have several outstanding complex requests for a
2767 * given address, one for each out-of-sync device.  We model this by allocating
2768 * a number of r10_bio structures, one for each out-of-sync device.
2769 * As we setup these structures, we collect all bio's together into a list
2770 * which we then process collectively to add pages, and then process again
2771 * to pass to generic_make_request.
2772 *
2773 * The r10_bio structures are linked using a borrowed master_bio pointer.
2774 * This link is counted in ->remaining.  When the r10_bio that points to NULL
2775 * has its remaining count decremented to 0, the whole complex operation
2776 * is complete.
2777 *
2778 */
2779
2780static sector_t sync_request(struct mddev *mddev, sector_t sector_nr,
2781                             int *skipped, int go_faster)
2782{
2783        struct r10conf *conf = mddev->private;
2784        struct r10bio *r10_bio;
2785        struct bio *biolist = NULL, *bio;
2786        sector_t max_sector, nr_sectors;
2787        int i;
2788        int max_sync;
2789        sector_t sync_blocks;
2790        sector_t sectors_skipped = 0;
2791        int chunks_skipped = 0;
2792        sector_t chunk_mask = conf->geo.chunk_mask;
2793
2794        if (!conf->r10buf_pool)
2795                if (init_resync(conf))
2796                        return 0;
2797
2798 skipped:
2799        max_sector = mddev->dev_sectors;
2800        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
2801            test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2802                max_sector = mddev->resync_max_sectors;
2803        if (sector_nr >= max_sector) {
2804                /* If we aborted, we need to abort the
2805                 * sync on the 'current' bitmap chucks (there can
2806                 * be several when recovering multiple devices).
2807                 * as we may have started syncing it but not finished.
2808                 * We can find the current address in
2809                 * mddev->curr_resync, but for recovery,
2810                 * we need to convert that to several
2811                 * virtual addresses.
2812                 */
2813                if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
2814                        end_reshape(conf);
2815                        return 0;
2816                }
2817
2818                if (mddev->curr_resync < max_sector) { /* aborted */
2819                        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
2820                                bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2821                                                &sync_blocks, 1);
2822                        else for (i = 0; i < conf->geo.raid_disks; i++) {
2823                                sector_t sect =
2824                                        raid10_find_virt(conf, mddev->curr_resync, i);
2825                                bitmap_end_sync(mddev->bitmap, sect,
2826                                                &sync_blocks, 1);
2827                        }
2828                } else {
2829                        /* completed sync */
2830                        if ((!mddev->bitmap || conf->fullsync)
2831                            && conf->have_replacement
2832                            && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
2833                                /* Completed a full sync so the replacements
2834                                 * are now fully recovered.
2835                                 */
2836                                for (i = 0; i < conf->geo.raid_disks; i++)
2837                                        if (conf->mirrors[i].replacement)
2838                                                conf->mirrors[i].replacement
2839                                                        ->recovery_offset
2840                                                        = MaxSector;
2841                        }
2842                        conf->fullsync = 0;
2843                }
2844                bitmap_close_sync(mddev->bitmap);
2845                close_sync(conf);
2846                *skipped = 1;
2847                return sectors_skipped;
2848        }
2849
2850        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2851                return reshape_request(mddev, sector_nr, skipped);
2852
2853        if (chunks_skipped >= conf->geo.raid_disks) {
2854                /* if there has been nothing to do on any drive,
2855                 * then there is nothing to do at all..
2856                 */
2857                *skipped = 1;
2858                return (max_sector - sector_nr) + sectors_skipped;
2859        }
2860
2861        if (max_sector > mddev->resync_max)
2862                max_sector = mddev->resync_max; /* Don't do IO beyond here */
2863
2864        /* make sure whole request will fit in a chunk - if chunks
2865         * are meaningful
2866         */
2867        if (conf->geo.near_copies < conf->geo.raid_disks &&
2868            max_sector > (sector_nr | chunk_mask))
2869                max_sector = (sector_nr | chunk_mask) + 1;
2870        /*
2871         * If there is non-resync activity waiting for us then
2872         * put in a delay to throttle resync.
2873         */
2874        if (!go_faster && conf->nr_waiting)
2875                msleep_interruptible(1000);
2876
2877        /* Again, very different code for resync and recovery.
2878         * Both must result in an r10bio with a list of bios that
2879         * have bi_end_io, bi_sector, bi_bdev set,
2880         * and bi_private set to the r10bio.
2881         * For recovery, we may actually create several r10bios
2882         * with 2 bios in each, that correspond to the bios in the main one.
2883         * In this case, the subordinate r10bios link back through a
2884         * borrowed master_bio pointer, and the counter in the master
2885         * includes a ref from each subordinate.
2886         */
2887        /* First, we decide what to do and set ->bi_end_io
2888         * To end_sync_read if we want to read, and
2889         * end_sync_write if we will want to write.
2890         */
2891
2892        max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
2893        if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
2894                /* recovery... the complicated one */
2895                int j;
2896                r10_bio = NULL;
2897
2898                for (i = 0 ; i < conf->geo.raid_disks; i++) {
2899                        int still_degraded;
2900                        struct r10bio *rb2;
2901                        sector_t sect;
2902                        int must_sync;
2903                        int any_working;
2904                        struct raid10_info *mirror = &conf->mirrors[i];
2905
2906                        if ((mirror->rdev == NULL ||
2907                             test_bit(In_sync, &mirror->rdev->flags))
2908                            &&
2909                            (mirror->replacement == NULL ||
2910                             test_bit(Faulty,
2911                                      &mirror->replacement->flags)))
2912                                continue;
2913
2914                        still_degraded = 0;
2915                        /* want to reconstruct this device */
2916                        rb2 = r10_bio;
2917                        sect = raid10_find_virt(conf, sector_nr, i);
2918                        if (sect >= mddev->resync_max_sectors) {
2919                                /* last stripe is not complete - don't
2920                                 * try to recover this sector.
2921                                 */
2922                                continue;
2923                        }
2924                        /* Unless we are doing a full sync, or a replacement
2925                         * we only need to recover the block if it is set in
2926                         * the bitmap
2927                         */
2928                        must_sync = bitmap_start_sync(mddev->bitmap, sect,
2929                                                      &sync_blocks, 1);
2930                        if (sync_blocks < max_sync)
2931                                max_sync = sync_blocks;
2932                        if (!must_sync &&
2933                            mirror->replacement == NULL &&
2934                            !conf->fullsync) {
2935                                /* yep, skip the sync_blocks here, but don't assume
2936                                 * that there will never be anything to do here
2937                                 */
2938                                chunks_skipped = -1;
2939                                continue;
2940                        }
2941
2942                        r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
2943                        raise_barrier(conf, rb2 != NULL);
2944                        atomic_set(&r10_bio->remaining, 0);
2945
2946                        r10_bio->master_bio = (struct bio*)rb2;
2947                        if (rb2)
2948                                atomic_inc(&rb2->remaining);
2949                        r10_bio->mddev = mddev;
2950                        set_bit(R10BIO_IsRecover, &r10_bio->state);
2951                        r10_bio->sector = sect;
2952
2953                        raid10_find_phys(conf, r10_bio);
2954
2955                        /* Need to check if the array will still be
2956                         * degraded
2957                         */
2958                        for (j = 0; j < conf->geo.raid_disks; j++)
2959                                if (conf->mirrors[j].rdev == NULL ||
2960                                    test_bit(Faulty, &conf->mirrors[j].rdev->flags)) {
2961                                        still_degraded = 1;
2962                                        break;
2963                                }
2964
2965                        must_sync = bitmap_start_sync(mddev->bitmap, sect,
2966                                                      &sync_blocks, still_degraded);
2967
2968                        any_working = 0;
2969                        for (j=0; j<conf->copies;j++) {
2970                                int k;
2971                                int d = r10_bio->devs[j].devnum;
2972                                sector_t from_addr, to_addr;
2973                                struct md_rdev *rdev;
2974                                sector_t sector, first_bad;
2975                                int bad_sectors;
2976                                if (!conf->mirrors[d].rdev ||
2977                                    !test_bit(In_sync, &conf->mirrors[d].rdev->flags))
2978                                        continue;
2979                                /* This is where we read from */
2980                                any_working = 1;
2981                                rdev = conf->mirrors[d].rdev;
2982                                sector = r10_bio->devs[j].addr;
2983
2984                                if (is_badblock(rdev, sector, max_sync,
2985                                                &first_bad, &bad_sectors)) {
2986                                        if (first_bad > sector)
2987                                                max_sync = first_bad - sector;
2988                                        else {
2989                                                bad_sectors -= (sector
2990                                                                - first_bad);
2991                                                if (max_sync > bad_sectors)
2992                                                        max_sync = bad_sectors;
2993                                                continue;
2994                                        }
2995                                }
2996                                bio = r10_bio->devs[0].bio;
2997                                bio->bi_next = biolist;
2998                                biolist = bio;
2999                                bio->bi_private = r10_bio;
3000                                bio->bi_end_io = end_sync_read;
3001                                bio->bi_rw = READ;
3002                                from_addr = r10_bio->devs[j].addr;
3003                                bio->bi_sector = from_addr + rdev->data_offset;
3004                                bio->bi_bdev = rdev->bdev;
3005                                atomic_inc(&rdev->nr_pending);
3006                                /* and we write to 'i' (if not in_sync) */
3007
3008                                for (k=0; k<conf->copies; k++)
3009                                        if (r10_bio->devs[k].devnum == i)
3010                                                break;
3011                                BUG_ON(k == conf->copies);
3012                                to_addr = r10_bio->devs[k].addr;
3013                                r10_bio->devs[0].devnum = d;
3014                                r10_bio->devs[0].addr = from_addr;
3015                                r10_bio->devs[1].devnum = i;
3016                                r10_bio->devs[1].addr = to_addr;
3017
3018                                rdev = mirror->rdev;
3019                                if (!test_bit(In_sync, &rdev->flags)) {
3020                                        bio = r10_bio->devs[1].bio;
3021                                        bio->bi_next = biolist;
3022                                        biolist = bio;
3023                                        bio->bi_private = r10_bio;
3024                                        bio->bi_end_io = end_sync_write;
3025                                        bio->bi_rw = WRITE;
3026                                        bio->bi_sector = to_addr
3027                                                + rdev->data_offset;
3028                                        bio->bi_bdev = rdev->bdev;
3029                                        atomic_inc(&r10_bio->remaining);
3030                                } else
3031                                        r10_bio->devs[1].bio->bi_end_io = NULL;
3032
3033                                /* and maybe write to replacement */
3034                                bio = r10_bio->devs[1].repl_bio;
3035                                if (bio)
3036                                        bio->bi_end_io = NULL;
3037                                rdev = mirror->replacement;
3038                                /* Note: if rdev != NULL, then bio
3039                                 * cannot be NULL as r10buf_pool_alloc will
3040                                 * have allocated it.
3041                                 * So the second test here is pointless.
3042                                 * But it keeps semantic-checkers happy, and
3043                                 * this comment keeps human reviewers
3044                                 * happy.
3045                                 */
3046                                if (rdev == NULL || bio == NULL ||
3047                                    test_bit(Faulty, &rdev->flags))
3048                                        break;
3049                                bio->bi_next = biolist;
3050                                biolist = bio;
3051                                bio->bi_private = r10_bio;
3052                                bio->bi_end_io = end_sync_write;
3053                                bio->bi_rw = WRITE;
3054                                bio->bi_sector = to_addr + rdev->data_offset;
3055                                bio->bi_bdev = rdev->bdev;
3056                                atomic_inc(&r10_bio->remaining);
3057                                break;
3058                        }
3059                        if (j == conf->copies) {
3060                                /* Cannot recover, so abort the recovery or
3061                                 * record a bad block */
3062                                put_buf(r10_bio);
3063                                if (rb2)
3064                                        atomic_dec(&rb2->remaining);
3065                                r10_bio = rb2;
3066                                if (any_working) {
3067                                        /* problem is that there are bad blocks
3068                                         * on other device(s)
3069                                         */
3070                                        int k;
3071                                        for (k = 0; k < conf->copies; k++)
3072                                                if (r10_bio->devs[k].devnum == i)
3073                                                        break;
3074                                        if (!test_bit(In_sync,
3075                                                      &mirror->rdev->flags)
3076                                            && !rdev_set_badblocks(
3077                                                    mirror->rdev,
3078                                                    r10_bio->devs[k].addr,
3079                                                    max_sync, 0))
3080                                                any_working = 0;
3081                                        if (mirror->replacement &&
3082                                            !rdev_set_badblocks(
3083                                                    mirror->replacement,
3084                                                    r10_bio->devs[k].addr,
3085                                                    max_sync, 0))
3086                                                any_working = 0;
3087                                }
3088                                if (!any_working)  {
3089                                        if (!test_and_set_bit(MD_RECOVERY_INTR,
3090                                                              &mddev->recovery))
3091                                                printk(KERN_INFO "md/raid10:%s: insufficient "
3092                                                       "working devices for recovery.\n",
3093                                                       mdname(mddev));
3094                                        mirror->recovery_disabled
3095                                                = mddev->recovery_disabled;
3096                                }
3097                                break;
3098                        }
3099                }
3100                if (biolist == NULL) {
3101                        while (r10_bio) {
3102                                struct r10bio *rb2 = r10_bio;
3103                                r10_bio = (struct r10bio*) rb2->master_bio;
3104                                rb2->master_bio = NULL;
3105                                put_buf(rb2);
3106                        }
3107                        goto giveup;
3108                }
3109        } else {
3110                /* resync. Schedule a read for every block at this virt offset */
3111                int count = 0;
3112
3113                bitmap_cond_end_sync(mddev->bitmap, sector_nr);
3114
3115                if (!bitmap_start_sync(mddev->bitmap, sector_nr,
3116                                       &sync_blocks, mddev->degraded) &&
3117                    !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED,
3118                                                 &mddev->recovery)) {
3119                        /* We can skip this block */
3120                        *skipped = 1;
3121                        return sync_blocks + sectors_skipped;
3122                }
3123                if (sync_blocks < max_sync)
3124                        max_sync = sync_blocks;
3125                r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
3126
3127                r10_bio->mddev = mddev;
3128                atomic_set(&r10_bio->remaining, 0);
3129                raise_barrier(conf, 0);
3130                conf->next_resync = sector_nr;
3131
3132                r10_bio->master_bio = NULL;
3133                r10_bio->sector = sector_nr;
3134                set_bit(R10BIO_IsSync, &r10_bio->state);
3135                raid10_find_phys(conf, r10_bio);
3136                r10_bio->sectors = (sector_nr | chunk_mask) - sector_nr + 1;
3137
3138                for (i = 0; i < conf->copies; i++) {
3139                        int d = r10_bio->devs[i].devnum;
3140                        sector_t first_bad, sector;
3141                        int bad_sectors;
3142
3143                        if (r10_bio->devs[i].repl_bio)
3144                                r10_bio->devs[i].repl_bio->bi_end_io = NULL;
3145
3146                        bio = r10_bio->devs[i].bio;
3147                        bio->bi_end_io = NULL;
3148                        clear_bit(BIO_UPTODATE, &bio->bi_flags);
3149                        if (conf->mirrors[d].rdev == NULL ||
3150                            test_bit(Faulty, &conf->mirrors[d].rdev->flags))
3151                                continue;
3152                        sector = r10_bio->devs[i].addr;
3153                        if (is_badblock(conf->mirrors[d].rdev,
3154                                        sector, max_sync,
3155                                        &first_bad, &bad_sectors)) {
3156                                if (first_bad > sector)
3157                                        max_sync = first_bad - sector;
3158                                else {
3159                                        bad_sectors -= (sector - first_bad);
3160                                        if (max_sync > bad_sectors)
3161                                                max_sync = bad_sectors;
3162                                        continue;
3163                                }
3164                        }
3165                        atomic_inc(&conf->mirrors[d].rdev->nr_pending);
3166                        atomic_inc(&r10_bio->remaining);
3167                        bio->bi_next = biolist;
3168                        biolist = bio;
3169                        bio->bi_private = r10_bio;
3170                        bio->bi_end_io = end_sync_read;
3171                        bio->bi_rw = READ;
3172                        bio->bi_sector = sector +
3173                                conf->mirrors[d].rdev->data_offset;
3174                        bio->bi_bdev = conf->mirrors[d].rdev->bdev;
3175                        count++;
3176
3177                        if (conf->mirrors[d].replacement == NULL ||
3178                            test_bit(Faulty,
3179                                     &conf->mirrors[d].replacement->flags))
3180                                continue;
3181
3182                        /* Need to set up for writing to the replacement */
3183                        bio = r10_bio->devs[i].repl_bio;
3184                        clear_bit(BIO_UPTODATE, &bio->bi_flags);
3185
3186                        sector = r10_bio->devs[i].addr;
3187                        atomic_inc(&conf->mirrors[d].rdev->nr_pending);
3188                        bio->bi_next = biolist;
3189                        biolist = bio;
3190                        bio->bi_private = r10_bio;
3191                        bio->bi_end_io = end_sync_write;
3192                        bio->bi_rw = WRITE;
3193                        bio->bi_sector = sector +
3194                                conf->mirrors[d].replacement->data_offset;
3195                        bio->bi_bdev = conf->mirrors[d].replacement->bdev;
3196                        count++;
3197                }
3198
3199                if (count < 2) {
3200                        for (i=0; i<conf->copies; i++) {
3201                                int d = r10_bio->devs[i].devnum;
3202                                if (r10_bio->devs[i].bio->bi_end_io)
3203                                        rdev_dec_pending(conf->mirrors[d].rdev,
3204                                                         mddev);
3205                                if (r10_bio->devs[i].repl_bio &&
3206                                    r10_bio->devs[i].repl_bio->bi_end_io)
3207                                        rdev_dec_pending(
3208                                                conf->mirrors[d].replacement,
3209                                                mddev);
3210                        }
3211                        put_buf(r10_bio);
3212                        biolist = NULL;
3213                        goto giveup;
3214                }
3215        }
3216
3217        for (bio = biolist; bio ; bio=bio->bi_next) {
3218
3219                bio->bi_flags &= ~(BIO_POOL_MASK - 1);
3220                if (bio->bi_end_io)
3221                        bio->bi_flags |= 1 << BIO_UPTODATE;
3222                bio->bi_vcnt = 0;
3223                bio->bi_idx = 0;
3224                bio->bi_phys_segments = 0;
3225                bio->bi_size = 0;
3226        }
3227
3228        nr_sectors = 0;
3229        if (sector_nr + max_sync < max_sector)
3230                max_sector = sector_nr + max_sync;
3231        do {
3232                struct page *page;
3233                int len = PAGE_SIZE;
3234                if (sector_nr + (len>>9) > max_sector)
3235                        len = (max_sector - sector_nr) << 9;
3236                if (len == 0)
3237                        break;
3238                for (bio= biolist ; bio ; bio=bio->bi_next) {
3239                        struct bio *bio2;
3240                        page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
3241                        if (bio_add_page(bio, page, len, 0))
3242                                continue;
3243
3244                        /* stop here */
3245                        bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
3246                        for (bio2 = biolist;
3247                             bio2 && bio2 != bio;
3248                             bio2 = bio2->bi_next) {
3249                                /* remove last page from this bio */
3250                                bio2->bi_vcnt--;
3251                                bio2->bi_size -= len;
3252                                bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
3253                        }
3254                        goto bio_full;
3255                }
3256                nr_sectors += len>>9;
3257                sector_nr += len>>9;
3258        } while (biolist->bi_vcnt < RESYNC_PAGES);
3259 bio_full:
3260        r10_bio->sectors = nr_sectors;
3261
3262        while (biolist) {
3263                bio = biolist;
3264                biolist = biolist->bi_next;
3265
3266                bio->bi_next = NULL;
3267                r10_bio = bio->bi_private;
3268                r10_bio->sectors = nr_sectors;
3269
3270                if (bio->bi_end_io == end_sync_read) {
3271                        md_sync_acct(bio->bi_bdev, nr_sectors);
3272                        generic_make_request(bio);
3273                }
3274        }
3275
3276        if (sectors_skipped)
3277                /* pretend they weren't skipped, it makes
3278                 * no important difference in this case
3279                 */
3280                md_done_sync(mddev, sectors_skipped, 1);
3281
3282        return sectors_skipped + nr_sectors;
3283 giveup:
3284        /* There is nowhere to write, so all non-sync
3285         * drives must be failed or in resync, all drives
3286         * have a bad block, so try the next chunk...
3287         */
3288        if (sector_nr + max_sync < max_sector)
3289                max_sector = sector_nr + max_sync;
3290
3291        sectors_skipped += (max_sector - sector_nr);
3292        chunks_skipped ++;
3293        sector_nr = max_sector;
3294        goto skipped;
3295}
3296
3297static sector_t
3298raid10_size(struct mddev *mddev, sector_t sectors, int raid_disks)
3299{
3300        sector_t size;
3301        struct r10conf *conf = mddev->private;
3302
3303        if (!raid_disks)
3304                raid_disks = min(conf->geo.raid_disks,
3305                                 conf->prev.raid_disks);
3306        if (!sectors)
3307                sectors = conf->dev_sectors;
3308
3309        size = sectors >> conf->geo.chunk_shift;
3310        sector_div(size, conf->geo.far_copies);
3311        size = size * raid_disks;
3312        sector_div(size, conf->geo.near_copies);
3313
3314        return size << conf->geo.chunk_shift;
3315}
3316
3317static void calc_sectors(struct r10conf *conf, sector_t size)
3318{
3319        /* Calculate the number of sectors-per-device that will
3320         * actually be used, and set conf->dev_sectors and
3321         * conf->stride
3322         */
3323
3324        size = size >> conf->geo.chunk_shift;
3325        sector_div(size, conf->geo.far_copies);
3326        size = size * conf->geo.raid_disks;
3327        sector_div(size, conf->geo.near_copies);
3328        /* 'size' is now the number of chunks in the array */
3329        /* calculate "used chunks per device" */
3330        size = size * conf->copies;
3331
3332        /* We need to round up when dividing by raid_disks to
3333         * get the stride size.
3334         */
3335        size = DIV_ROUND_UP_SECTOR_T(size, conf->geo.raid_disks);
3336
3337        conf->dev_sectors = size << conf->geo.chunk_shift;
3338
3339        if (conf->geo.far_offset)
3340                conf->geo.stride = 1 << conf->geo.chunk_shift;
3341        else {
3342                sector_div(size, conf->geo.far_copies);
3343                conf->geo.stride = size << conf->geo.chunk_shift;
3344        }
3345}
3346
3347enum geo_type {geo_new, geo_old, geo_start};
3348static int setup_geo(struct geom *geo, struct mddev *mddev, enum geo_type new)
3349{
3350        int nc, fc, fo;
3351        int layout, chunk, disks;
3352        switch (new) {
3353        case geo_old:
3354                layout = mddev->layout;
3355                chunk = mddev->chunk_sectors;
3356                disks = mddev->raid_disks - mddev->delta_disks;
3357                break;
3358        case geo_new:
3359                layout = mddev->new_layout;
3360                chunk = mddev->new_chunk_sectors;
3361                disks = mddev->raid_disks;
3362                break;
3363        default: /* avoid 'may be unused' warnings */
3364        case geo_start: /* new when starting reshape - raid_disks not
3365                         * updated yet. */
3366                layout = mddev->new_layout;
3367                chunk = mddev->new_chunk_sectors;
3368                disks = mddev->raid_disks + mddev->delta_disks;
3369                break;
3370        }
3371        if (layout >> 17)
3372                return -1;
3373        if (chunk < (PAGE_SIZE >> 9) ||
3374            !is_power_of_2(chunk))
3375                return -2;
3376        nc = layout & 255;
3377        fc = (layout >> 8) & 255;
3378        fo = layout & (1<<16);
3379        geo->raid_disks = disks;
3380        geo->near_copies = nc;
3381        geo->far_copies = fc;
3382        geo->far_offset = fo;
3383        geo->chunk_mask = chunk - 1;
3384        geo->chunk_shift = ffz(~chunk);
3385        return nc*fc;
3386}
3387
3388static struct r10conf *setup_conf(struct mddev *mddev)
3389{
3390        struct r10conf *conf = NULL;
3391        int err = -EINVAL;
3392        struct geom geo;
3393        int copies;
3394
3395        copies = setup_geo(&geo, mddev, geo_new);
3396
3397        if (copies == -2) {
3398                printk(KERN_ERR "md/raid10:%s: chunk size must be "
3399                       "at least PAGE_SIZE(%ld) and be a power of 2.\n",
3400                       mdname(mddev), PAGE_SIZE);
3401                goto out;
3402        }
3403
3404        if (copies < 2 || copies > mddev->raid_disks) {
3405                printk(KERN_ERR "md/raid10:%s: unsupported raid10 layout: 0x%8x\n",
3406                       mdname(mddev), mddev->new_layout);
3407                goto out;
3408        }
3409
3410        err = -ENOMEM;
3411        conf = kzalloc(sizeof(struct r10conf), GFP_KERNEL);
3412        if (!conf)
3413                goto out;
3414
3415        /* FIXME calc properly */
3416        conf->mirrors = kzalloc(sizeof(struct raid10_info)*(mddev->raid_disks +
3417                                                            max(0,mddev->delta_disks)),
3418                                GFP_KERNEL);
3419        if (!conf->mirrors)
3420                goto out;
3421
3422        conf->tmppage = alloc_page(GFP_KERNEL);
3423        if (!conf->tmppage)
3424                goto out;
3425
3426        conf->geo = geo;
3427        conf->copies = copies;
3428        conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
3429                                           r10bio_pool_free, conf);
3430        if (!conf->r10bio_pool)
3431                goto out;
3432
3433        calc_sectors(conf, mddev->dev_sectors);
3434        if (mddev->reshape_position == MaxSector) {
3435                conf->prev = conf->geo;
3436                conf->reshape_progress = MaxSector;
3437        } else {
3438                if (setup_geo(&conf->prev, mddev, geo_old) != conf->copies) {
3439                        err = -EINVAL;
3440                        goto out;
3441                }
3442                conf->reshape_progress = mddev->reshape_position;
3443                if (conf->prev.far_offset)
3444                        conf->prev.stride = 1 << conf->prev.chunk_shift;
3445                else
3446                        /* far_copies must be 1 */
3447                        conf->prev.stride = conf->dev_sectors;
3448        }
3449        spin_lock_init(&conf->device_lock);
3450        INIT_LIST_HEAD(&conf->retry_list);
3451
3452        spin_lock_init(&conf->resync_lock);
3453        init_waitqueue_head(&conf->wait_barrier);
3454
3455        conf->thread = md_register_thread(raid10d, mddev, "raid10");
3456        if (!conf->thread)
3457                goto out;
3458
3459        conf->mddev = mddev;
3460        return conf;
3461
3462 out:
3463        if (err == -ENOMEM)
3464                printk(KERN_ERR "md/raid10:%s: couldn't allocate memory.\n",
3465                       mdname(mddev));
3466        if (conf) {
3467                if (conf->r10bio_pool)
3468                        mempool_destroy(conf->r10bio_pool);
3469                kfree(conf->mirrors);
3470                safe_put_page(conf->tmppage);
3471                kfree(conf);
3472        }
3473        return ERR_PTR(err);
3474}
3475
3476static int run(struct mddev *mddev)
3477{
3478        struct r10conf *conf;
3479        int i, disk_idx, chunk_size;
3480        struct raid10_info *disk;
3481        struct md_rdev *rdev;
3482        sector_t size;
3483        sector_t min_offset_diff = 0;
3484        int first = 1;
3485
3486        if (mddev->private == NULL) {
3487                conf = setup_conf(mddev);
3488                if (IS_ERR(conf))
3489                        return PTR_ERR(conf);
3490                mddev->private = conf;
3491        }
3492        conf = mddev->private;
3493        if (!conf)
3494                goto out;
3495
3496        mddev->thread = conf->thread;
3497        conf->thread = NULL;
3498
3499        chunk_size = mddev->chunk_sectors << 9;
3500        if (mddev->queue) {
3501                blk_queue_io_min(mddev->queue, chunk_size);
3502                if (conf->geo.raid_disks % conf->geo.near_copies)
3503                        blk_queue_io_opt(mddev->queue, chunk_size * conf->geo.raid_disks);
3504                else
3505                        blk_queue_io_opt(mddev->queue, chunk_size *
3506                                         (conf->geo.raid_disks / conf->geo.near_copies));
3507        }
3508
3509        rdev_for_each(rdev, mddev) {
3510                long long diff;
3511                struct request_queue *q;
3512
3513                disk_idx = rdev->raid_disk;
3514                if (disk_idx < 0)
3515                        continue;
3516                if (disk_idx >= conf->geo.raid_disks &&
3517                    disk_idx >= conf->prev.raid_disks)
3518                        continue;
3519                disk = conf->mirrors + disk_idx;
3520
3521                if (test_bit(Replacement, &rdev->flags)) {
3522                        if (disk->replacement)
3523                                goto out_free_conf;
3524                        disk->replacement = rdev;
3525                } else {
3526                        if (disk->rdev)
3527                                goto out_free_conf;
3528                        disk->rdev = rdev;
3529                }
3530                q = bdev_get_queue(rdev->bdev);
3531                if (q->merge_bvec_fn)
3532                        mddev->merge_check_needed = 1;
3533                diff = (rdev->new_data_offset - rdev->data_offset);
3534                if (!mddev->reshape_backwards)
3535                        diff = -diff;
3536                if (diff < 0)
3537                        diff = 0;
3538                if (first || diff < min_offset_diff)
3539                        min_offset_diff = diff;
3540
3541                if (mddev->gendisk)
3542                        disk_stack_limits(mddev->gendisk, rdev->bdev,
3543                                          rdev->data_offset << 9);
3544
3545                disk->head_position = 0;
3546        }
3547
3548        /* need to check that every block has at least one working mirror */
3549        if (!enough(conf, -1)) {
3550                printk(KERN_ERR "md/raid10:%s: not enough operational mirrors.\n",
3551                       mdname(mddev));
3552                goto out_free_conf;
3553        }
3554
3555        if (conf->reshape_progress != MaxSector) {
3556                /* must ensure that shape change is supported */
3557                if (conf->geo.far_copies != 1 &&
3558                    conf->geo.far_offset == 0)
3559                        goto out_free_conf;
3560                if (conf->prev.far_copies != 1 &&
3561                    conf->geo.far_offset == 0)
3562                        goto out_free_conf;
3563        }
3564
3565        mddev->degraded = 0;
3566        for (i = 0;
3567             i < conf->geo.raid_disks
3568                     || i < conf->prev.raid_disks;
3569             i++) {
3570
3571                disk = conf->mirrors + i;
3572
3573                if (!disk->rdev && disk->replacement) {
3574                        /* The replacement is all we have - use it */
3575                        disk->rdev = disk->replacement;
3576                        disk->replacement = NULL;
3577                        clear_bit(Replacement, &disk->rdev->flags);
3578                }
3579
3580                if (!disk->rdev ||
3581                    !test_bit(In_sync, &disk->rdev->flags)) {
3582                        disk->head_position = 0;
3583                        mddev->degraded++;
3584                        if (disk->rdev)
3585                                conf->fullsync = 1;
3586                }
3587                disk->recovery_disabled = mddev->recovery_disabled - 1;
3588        }
3589
3590        if (mddev->recovery_cp != MaxSector)
3591                printk(KERN_NOTICE "md/raid10:%s: not clean"
3592                       " -- starting background reconstruction\n",
3593                       mdname(mddev));
3594        printk(KERN_INFO
3595                "md/raid10:%s: active with %d out of %d devices\n",
3596                mdname(mddev), conf->geo.raid_disks - mddev->degraded,
3597                conf->geo.raid_disks);
3598        /*
3599         * Ok, everything is just fine now
3600         */
3601        mddev->dev_sectors = conf->dev_sectors;
3602        size = raid10_size(mddev, 0, 0);
3603        md_set_array_sectors(mddev, size);
3604        mddev->resync_max_sectors = size;
3605
3606        if (mddev->queue) {
3607                int stripe = conf->geo.raid_disks *
3608                        ((mddev->chunk_sectors << 9) / PAGE_SIZE);
3609                mddev->queue->backing_dev_info.congested_fn = raid10_congested;
3610                mddev->queue->backing_dev_info.congested_data = mddev;
3611
3612                /* Calculate max read-ahead size.
3613                 * We need to readahead at least twice a whole stripe....
3614                 * maybe...
3615                 */
3616                stripe /= conf->geo.near_copies;
3617                if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
3618                        mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
3619                blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
3620        }
3621
3622
3623        if (md_integrity_register(mddev))
3624                goto out_free_conf;
3625
3626        if (conf->reshape_progress != MaxSector) {
3627                unsigned long before_length, after_length;
3628
3629                before_length = ((1 << conf->prev.chunk_shift) *
3630                                 conf->prev.far_copies);
3631                after_length = ((1 << conf->geo.chunk_shift) *
3632                                conf->geo.far_copies);
3633
3634                if (max(before_length, after_length) > min_offset_diff) {
3635                        /* This cannot work */
3636                        printk("md/raid10: offset difference not enough to continue reshape\n");
3637                        goto out_free_conf;
3638                }
3639                conf->offset_diff = min_offset_diff;
3640
3641                conf->reshape_safe = conf->reshape_progress;
3642                clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
3643                clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
3644                set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
3645                set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
3646                mddev->sync_thread = md_register_thread(md_do_sync, mddev,
3647                                                        "reshape");
3648        }
3649
3650        return 0;
3651
3652out_free_conf:
3653        md_unregister_thread(&mddev->thread);
3654        if (conf->r10bio_pool)
3655                mempool_destroy(conf->r10bio_pool);
3656        safe_put_page(conf->tmppage);
3657        kfree(conf->mirrors);
3658        kfree(conf);
3659        mddev->private = NULL;
3660out:
3661        return -EIO;
3662}
3663
3664static int stop(struct mddev *mddev)
3665{
3666        struct r10conf *conf = mddev->private;
3667
3668        raise_barrier(conf, 0);
3669        lower_barrier(conf);
3670
3671        md_unregister_thread(&mddev->thread);
3672        if (mddev->queue)
3673                /* the unplug fn references 'conf'*/
3674                blk_sync_queue(mddev->queue);
3675
3676        if (conf->r10bio_pool)
3677                mempool_destroy(conf->r10bio_pool);
3678        kfree(conf->mirrors);
3679        kfree(conf);
3680        mddev->private = NULL;
3681        return 0;
3682}
3683
3684static void raid10_quiesce(struct mddev *mddev, int state)
3685{
3686        struct r10conf *conf = mddev->private;
3687
3688        switch(state) {
3689        case 1:
3690                raise_barrier(conf, 0);
3691                break;
3692        case 0:
3693                lower_barrier(conf);
3694                break;
3695        }
3696}
3697
3698static int raid10_resize(struct mddev *mddev, sector_t sectors)
3699{
3700        /* Resize of 'far' arrays is not supported.
3701         * For 'near' and 'offset' arrays we can set the
3702         * number of sectors used to be an appropriate multiple
3703         * of the chunk size.
3704         * For 'offset', this is far_copies*chunksize.
3705         * For 'near' the multiplier is the LCM of
3706         * near_copies and raid_disks.
3707         * So if far_copies > 1 && !far_offset, fail.
3708         * Else find LCM(raid_disks, near_copy)*far_copies and
3709         * multiply by chunk_size.  Then round to this number.
3710         * This is mostly done by raid10_size()
3711         */
3712        struct r10conf *conf = mddev->private;
3713        sector_t oldsize, size;
3714
3715        if (mddev->reshape_position != MaxSector)
3716                return -EBUSY;
3717
3718        if (conf->geo.far_copies > 1 && !conf->geo.far_offset)
3719                return -EINVAL;
3720
3721        oldsize = raid10_size(mddev, 0, 0);
3722        size = raid10_size(mddev, sectors, 0);
3723        if (mddev->external_size &&
3724            mddev->array_sectors > size)
3725                return -EINVAL;
3726        if (mddev->bitmap) {
3727                int ret = bitmap_resize(mddev->bitmap, size, 0, 0);
3728                if (ret)
3729                        return ret;
3730        }
3731        md_set_array_sectors(mddev, size);
3732        set_capacity(mddev->gendisk, mddev->array_sectors);
3733        revalidate_disk(mddev->gendisk);
3734        if (sectors > mddev->dev_sectors &&
3735            mddev->recovery_cp > oldsize) {
3736                mddev->recovery_cp = oldsize;
3737                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3738        }
3739        calc_sectors(conf, sectors);
3740        mddev->dev_sectors = conf->dev_sectors;
3741        mddev->resync_max_sectors = size;
3742        return 0;
3743}
3744
3745static void *raid10_takeover_raid0(struct mddev *mddev)
3746{
3747        struct md_rdev *rdev;
3748        struct r10conf *conf;
3749
3750        if (mddev->degraded > 0) {
3751                printk(KERN_ERR "md/raid10:%s: Error: degraded raid0!\n",
3752                       mdname(mddev));
3753                return ERR_PTR(-EINVAL);
3754        }
3755
3756        /* Set new parameters */
3757        mddev->new_level = 10;
3758        /* new layout: far_copies = 1, near_copies = 2 */
3759        mddev->new_layout = (1<<8) + 2;
3760        mddev->new_chunk_sectors = mddev->chunk_sectors;
3761        mddev->delta_disks = mddev->raid_disks;
3762        mddev->raid_disks *= 2;
3763        /* make sure it will be not marked as dirty */
3764        mddev->recovery_cp = MaxSector;
3765
3766        conf = setup_conf(mddev);
3767        if (!IS_ERR(conf)) {
3768                rdev_for_each(rdev, mddev)
3769                        if (rdev->raid_disk >= 0)
3770                                rdev->new_raid_disk = rdev->raid_disk * 2;
3771                conf->barrier = 1;
3772        }
3773
3774        return conf;
3775}
3776
3777static void *raid10_takeover(struct mddev *mddev)
3778{
3779        struct r0conf *raid0_conf;
3780
3781        /* raid10 can take over:
3782         *  raid0 - providing it has only two drives
3783         */
3784        if (mddev->level == 0) {
3785                /* for raid0 takeover only one zone is supported */
3786                raid0_conf = mddev->private;
3787                if (raid0_conf->nr_strip_zones > 1) {
3788                        printk(KERN_ERR "md/raid10:%s: cannot takeover raid 0"
3789                               " with more than one zone.\n",
3790                               mdname(mddev));
3791                        return ERR_PTR(-EINVAL);
3792                }
3793                return raid10_takeover_raid0(mddev);
3794        }
3795        return ERR_PTR(-EINVAL);
3796}
3797
3798static int raid10_check_reshape(struct mddev *mddev)
3799{
3800        /* Called when there is a request to change
3801         * - layout (to ->new_layout)
3802         * - chunk size (to ->new_chunk_sectors)
3803         * - raid_disks (by delta_disks)
3804         * or when trying to restart a reshape that was ongoing.
3805         *
3806         * We need to validate the request and possibly allocate
3807         * space if that might be an issue later.
3808         *
3809         * Currently we reject any reshape of a 'far' mode array,
3810         * allow chunk size to change if new is generally acceptable,
3811         * allow raid_disks to increase, and allow
3812         * a switch between 'near' mode and 'offset' mode.
3813         */
3814        struct r10conf *conf = mddev->private;
3815        struct geom geo;
3816
3817        if (conf->geo.far_copies != 1 && !conf->geo.far_offset)
3818                return -EINVAL;
3819
3820        if (setup_geo(&geo, mddev, geo_start) != conf->copies)
3821                /* mustn't change number of copies */
3822                return -EINVAL;
3823        if (geo.far_copies > 1 && !geo.far_offset)
3824                /* Cannot switch to 'far' mode */
3825                return -EINVAL;
3826
3827        if (mddev->array_sectors & geo.chunk_mask)
3828                        /* not factor of array size */
3829                        return -EINVAL;
3830
3831        if (!enough(conf, -1))
3832                return -EINVAL;
3833
3834        kfree(conf->mirrors_new);
3835        conf->mirrors_new = NULL;
3836        if (mddev->delta_disks > 0) {
3837                /* allocate new 'mirrors' list */
3838                conf->mirrors_new = kzalloc(
3839                        sizeof(struct raid10_info)
3840                        *(mddev->raid_disks +
3841                          mddev->delta_disks),
3842                        GFP_KERNEL);
3843                if (!conf->mirrors_new)
3844                        return -ENOMEM;
3845        }
3846        return 0;
3847}
3848
3849/*
3850 * Need to check if array has failed when deciding whether to:
3851 *  - start an array
3852 *  - remove non-faulty devices
3853 *  - add a spare
3854 *  - allow a reshape
3855 * This determination is simple when no reshape is happening.
3856 * However if there is a reshape, we need to carefully check
3857 * both the before and after sections.
3858 * This is because some failed devices may only affect one
3859 * of the two sections, and some non-in_sync devices may
3860 * be insync in the section most affected by failed devices.
3861 */
3862static int calc_degraded(struct r10conf *conf)
3863{
3864        int degraded, degraded2;
3865        int i;
3866
3867        rcu_read_lock();
3868        degraded = 0;
3869        /* 'prev' section first */
3870        for (i = 0; i < conf->prev.raid_disks; i++) {
3871                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
3872                if (!rdev || test_bit(Faulty, &rdev->flags))
3873                        degraded++;
3874                else if (!test_bit(In_sync, &rdev->flags))
3875                        /* When we can reduce the number of devices in
3876                         * an array, this might not contribute to
3877                         * 'degraded'.  It does now.
3878                         */
3879                        degraded++;
3880        }
3881        rcu_read_unlock();
3882        if (conf->geo.raid_disks == conf->prev.raid_disks)
3883                return degraded;
3884        rcu_read_lock();
3885        degraded2 = 0;
3886        for (i = 0; i < conf->geo.raid_disks; i++) {
3887                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
3888                if (!rdev || test_bit(Faulty, &rdev->flags))
3889                        degraded2++;
3890                else if (!test_bit(In_sync, &rdev->flags)) {
3891                        /* If reshape is increasing the number of devices,
3892                         * this section has already been recovered, so
3893                         * it doesn't contribute to degraded.
3894                         * else it does.
3895                         */
3896                        if (conf->geo.raid_disks <= conf->prev.raid_disks)
3897                                degraded2++;
3898                }
3899        }
3900        rcu_read_unlock();
3901        if (degraded2 > degraded)
3902                return degraded2;
3903        return degraded;
3904}
3905
3906static int raid10_start_reshape(struct mddev *mddev)
3907{
3908        /* A 'reshape' has been requested. This commits
3909         * the various 'new' fields and sets MD_RECOVER_RESHAPE
3910         * This also checks if there are enough spares and adds them
3911         * to the array.
3912         * We currently require enough spares to make the final
3913         * array non-degraded.  We also require that the difference
3914         * between old and new data_offset - on each device - is
3915         * enough that we never risk over-writing.
3916         */
3917
3918        unsigned long before_length, after_length;
3919        sector_t min_offset_diff = 0;
3920        int first = 1;
3921        struct geom new;
3922        struct r10conf *conf = mddev->private;
3923        struct md_rdev *rdev;
3924        int spares = 0;
3925        int ret;
3926
3927        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
3928                return -EBUSY;
3929
3930        if (setup_geo(&new, mddev, geo_start) != conf->copies)
3931                return -EINVAL;
3932
3933        before_length = ((1 << conf->prev.chunk_shift) *
3934                         conf->prev.far_copies);
3935        after_length = ((1 << conf->geo.chunk_shift) *
3936                        conf->geo.far_copies);
3937
3938        rdev_for_each(rdev, mddev) {
3939                if (!test_bit(In_sync, &rdev->flags)
3940                    && !test_bit(Faulty, &rdev->flags))
3941                        spares++;
3942                if (rdev->raid_disk >= 0) {
3943                        long long diff = (rdev->new_data_offset
3944                                          - rdev->data_offset);
3945                        if (!mddev->reshape_backwards)
3946                                diff = -diff;
3947                        if (diff < 0)
3948                                diff = 0;
3949                        if (first || diff < min_offset_diff)
3950                                min_offset_diff = diff;
3951                }
3952        }
3953
3954        if (max(before_length, after_length) > min_offset_diff)
3955                return -EINVAL;
3956
3957        if (spares < mddev->delta_disks)
3958                return -EINVAL;
3959
3960        conf->offset_diff = min_offset_diff;
3961        spin_lock_irq(&conf->device_lock);
3962        if (conf->mirrors_new) {
3963                memcpy(conf->mirrors_new, conf->mirrors,
3964                       sizeof(struct raid10_info)*conf->prev.raid_disks);
3965                smp_mb();
3966                kfree(conf->mirrors_old); /* FIXME and elsewhere */
3967                conf->mirrors_old = conf->mirrors;
3968                conf->mirrors = conf->mirrors_new;
3969                conf->mirrors_new = NULL;
3970        }
3971        setup_geo(&conf->geo, mddev, geo_start);
3972        smp_mb();
3973        if (mddev->reshape_backwards) {
3974                sector_t size = raid10_size(mddev, 0, 0);
3975                if (size < mddev->array_sectors) {
3976                        spin_unlock_irq(&conf->device_lock);
3977                        printk(KERN_ERR "md/raid10:%s: array size must be reduce before number of disks\n",
3978                               mdname(mddev));
3979                        return -EINVAL;
3980                }
3981                mddev->resync_max_sectors = size;
3982                conf->reshape_progress = size;
3983        } else
3984                conf->reshape_progress = 0;
3985        spin_unlock_irq(&conf->device_lock);
3986
3987        if (mddev->delta_disks && mddev->bitmap) {
3988                ret = bitmap_resize(mddev->bitmap,
3989                                    raid10_size(mddev, 0,
3990                                                conf->geo.raid_disks),
3991                                    0, 0);
3992                if (ret)
3993                        goto abort;
3994        }
3995        if (mddev->delta_disks > 0) {
3996                rdev_for_each(rdev, mddev)
3997                        if (rdev->raid_disk < 0 &&
3998                            !test_bit(Faulty, &rdev->flags)) {
3999                                if (raid10_add_disk(mddev, rdev) == 0) {
4000                                        if (rdev->raid_disk >=
4001                                            conf->prev.raid_disks)
4002                                                set_bit(In_sync, &rdev->flags);
4003                                        else
4004                                                rdev->recovery_offset = 0;
4005
4006                                        if (sysfs_link_rdev(mddev, rdev))
4007                                                /* Failure here  is OK */;
4008                                }
4009                        } else if (rdev->raid_disk >= conf->prev.raid_disks
4010                                   && !test_bit(Faulty, &rdev->flags)) {
4011                                /* This is a spare that was manually added */
4012                                set_bit(In_sync, &rdev->flags);
4013                        }
4014        }
4015        /* When a reshape changes the number of devices,
4016         * ->degraded is measured against the larger of the
4017         * pre and  post numbers.
4018         */
4019        spin_lock_irq(&conf->device_lock);
4020        mddev->degraded = calc_degraded(conf);
4021        spin_unlock_irq(&conf->device_lock);
4022        mddev->raid_disks = conf->geo.raid_disks;
4023        mddev->reshape_position = conf->reshape_progress;
4024        set_bit(MD_CHANGE_DEVS, &mddev->flags);
4025
4026        clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4027        clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4028        set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4029        set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4030
4031        mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4032                                                "reshape");
4033        if (!mddev->sync_thread) {
4034                ret = -EAGAIN;
4035                goto abort;
4036        }
4037        conf->reshape_checkpoint = jiffies;
4038        md_wakeup_thread(mddev->sync_thread);
4039        md_new_event(mddev);
4040        return 0;
4041
4042abort:
4043        mddev->recovery = 0;
4044        spin_lock_irq(&conf->device_lock);
4045        conf->geo = conf->prev;
4046        mddev->raid_disks = conf->geo.raid_disks;
4047        rdev_for_each(rdev, mddev)
4048                rdev->new_data_offset = rdev->data_offset;
4049        smp_wmb();
4050        conf->reshape_progress = MaxSector;
4051        mddev->reshape_position = MaxSector;
4052        spin_unlock_irq(&conf->device_lock);
4053        return ret;
4054}
4055
4056/* Calculate the last device-address that could contain
4057 * any block from the chunk that includes the array-address 's'
4058 * and report the next address.
4059 * i.e. the address returned will be chunk-aligned and after
4060 * any data that is in the chunk containing 's'.
4061 */
4062static sector_t last_dev_address(sector_t s, struct geom *geo)
4063{
4064        s = (s | geo->chunk_mask) + 1;
4065        s >>= geo->chunk_shift;
4066        s *= geo->near_copies;
4067        s = DIV_ROUND_UP_SECTOR_T(s, geo->raid_disks);
4068        s *= geo->far_copies;
4069        s <<= geo->chunk_shift;
4070        return s;
4071}
4072
4073/* Calculate the first device-address that could contain
4074 * any block from the chunk that includes the array-address 's'.
4075 * This too will be the start of a chunk
4076 */
4077static sector_t first_dev_address(sector_t s, struct geom *geo)
4078{
4079        s >>= geo->chunk_shift;
4080        s *= geo->near_copies;
4081        sector_div(s, geo->raid_disks);
4082        s *= geo->far_copies;
4083        s <<= geo->chunk_shift;
4084        return s;
4085}
4086
4087static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
4088                                int *skipped)
4089{
4090        /* We simply copy at most one chunk (smallest of old and new)
4091         * at a time, possibly less if that exceeds RESYNC_PAGES,
4092         * or we hit a bad block or something.
4093         * This might mean we pause for normal IO in the middle of
4094         * a chunk, but that is not a problem was mddev->reshape_position
4095         * can record any location.
4096         *
4097         * If we will want to write to a location that isn't
4098         * yet recorded as 'safe' (i.e. in metadata on disk) then
4099         * we need to flush all reshape requests and update the metadata.
4100         *
4101         * When reshaping forwards (e.g. to more devices), we interpret
4102         * 'safe' as the earliest block which might not have been copied
4103         * down yet.  We divide this by previous stripe size and multiply
4104         * by previous stripe length to get lowest device offset that we
4105         * cannot write to yet.
4106         * We interpret 'sector_nr' as an address that we want to write to.
4107         * From this we use last_device_address() to find where we might
4108         * write to, and first_device_address on the  'safe' position.
4109         * If this 'next' write position is after the 'safe' position,
4110         * we must update the metadata to increase the 'safe' position.
4111         *
4112         * When reshaping backwards, we round in the opposite direction
4113         * and perform the reverse test:  next write position must not be
4114         * less than current safe position.
4115         *
4116         * In all this the minimum difference in data offsets
4117         * (conf->offset_diff - always positive) allows a bit of slack,
4118         * so next can be after 'safe', but not by more than offset_disk
4119         *
4120         * We need to prepare all the bios here before we start any IO
4121         * to ensure the size we choose is acceptable to all devices.
4122         * The means one for each copy for write-out and an extra one for
4123         * read-in.
4124         * We store the read-in bio in ->master_bio and the others in
4125         * ->devs[x].bio and ->devs[x].repl_bio.
4126         */
4127        struct r10conf *conf = mddev->private;
4128        struct r10bio *r10_bio;
4129        sector_t next, safe, last;
4130        int max_sectors;
4131        int nr_sectors;
4132        int s;
4133        struct md_rdev *rdev;
4134        int need_flush = 0;
4135        struct bio *blist;
4136        struct bio *bio, *read_bio;
4137        int sectors_done = 0;
4138
4139        if (sector_nr == 0) {
4140                /* If restarting in the middle, skip the initial sectors */
4141                if (mddev->reshape_backwards &&
4142                    conf->reshape_progress < raid10_size(mddev, 0, 0)) {
4143                        sector_nr = (raid10_size(mddev, 0, 0)
4144                                     - conf->reshape_progress);
4145                } else if (!mddev->reshape_backwards &&
4146                           conf->reshape_progress > 0)
4147                        sector_nr = conf->reshape_progress;
4148                if (sector_nr) {
4149                        mddev->curr_resync_completed = sector_nr;
4150                        sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4151                        *skipped = 1;
4152                        return sector_nr;
4153                }
4154        }
4155
4156        /* We don't use sector_nr to track where we are up to
4157         * as that doesn't work well for ->reshape_backwards.
4158         * So just use ->reshape_progress.
4159         */
4160        if (mddev->reshape_backwards) {
4161                /* 'next' is the earliest device address that we might
4162                 * write to for this chunk in the new layout
4163                 */
4164                next = first_dev_address(conf->reshape_progress - 1,
4165                                         &conf->geo);
4166
4167                /* 'safe' is the last device address that we might read from
4168                 * in the old layout after a restart
4169                 */
4170                safe = last_dev_address(conf->reshape_safe - 1,
4171                                        &conf->prev);
4172
4173                if (next + conf->offset_diff < safe)
4174                        need_flush = 1;
4175
4176                last = conf->reshape_progress - 1;
4177                sector_nr = last & ~(sector_t)(conf->geo.chunk_mask
4178                                               & conf->prev.chunk_mask);
4179                if (sector_nr + RESYNC_BLOCK_SIZE/512 < last)
4180                        sector_nr = last + 1 - RESYNC_BLOCK_SIZE/512;
4181        } else {
4182                /* 'next' is after the last device address that we
4183                 * might write to for this chunk in the new layout
4184                 */
4185                next = last_dev_address(conf->reshape_progress, &conf->geo);
4186
4187                /* 'safe' is the earliest device address that we might
4188                 * read from in the old layout after a restart
4189                 */
4190                safe = first_dev_address(conf->reshape_safe, &conf->prev);
4191
4192                /* Need to update metadata if 'next' might be beyond 'safe'
4193                 * as that would possibly corrupt data
4194                 */
4195                if (next > safe + conf->offset_diff)
4196                        need_flush = 1;
4197
4198                sector_nr = conf->reshape_progress;
4199                last  = sector_nr | (conf->geo.chunk_mask
4200                                     & conf->prev.chunk_mask);
4201
4202                if (sector_nr + RESYNC_BLOCK_SIZE/512 <= last)
4203                        last = sector_nr + RESYNC_BLOCK_SIZE/512 - 1;
4204        }
4205
4206        if (need_flush ||
4207            time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4208                /* Need to update reshape_position in metadata */
4209                wait_barrier(conf);
4210                mddev->reshape_position = conf->reshape_progress;
4211                if (mddev->reshape_backwards)
4212                        mddev->curr_resync_completed = raid10_size(mddev, 0, 0)
4213                                - conf->reshape_progress;
4214                else
4215                        mddev->curr_resync_completed = conf->reshape_progress;
4216                conf->reshape_checkpoint = jiffies;
4217                set_bit(MD_CHANGE_DEVS, &mddev->flags);
4218                md_wakeup_thread(mddev->thread);
4219                wait_event(mddev->sb_wait, mddev->flags == 0 ||
4220                           kthread_should_stop());
4221                conf->reshape_safe = mddev->reshape_position;
4222                allow_barrier(conf);
4223        }
4224
4225read_more:
4226        /* Now schedule reads for blocks from sector_nr to last */
4227        r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
4228        raise_barrier(conf, sectors_done != 0);
4229        atomic_set(&r10_bio->remaining, 0);
4230        r10_bio->mddev = mddev;
4231        r10_bio->sector = sector_nr;
4232        set_bit(R10BIO_IsReshape, &r10_bio->state);
4233        r10_bio->sectors = last - sector_nr + 1;
4234        rdev = read_balance(conf, r10_bio, &max_sectors);
4235        BUG_ON(!test_bit(R10BIO_Previous, &r10_bio->state));
4236
4237        if (!rdev) {
4238                /* Cannot read from here, so need to record bad blocks
4239                 * on all the target devices.
4240                 */
4241                // FIXME
4242                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
4243                return sectors_done;
4244        }
4245
4246        read_bio = bio_alloc_mddev(GFP_KERNEL, RESYNC_PAGES, mddev);
4247
4248        read_bio->bi_bdev = rdev->bdev;
4249        read_bio->bi_sector = (r10_bio->devs[r10_bio->read_slot].addr
4250                               + rdev->data_offset);
4251        read_bio->bi_private = r10_bio;
4252        read_bio->bi_end_io = end_sync_read;
4253        read_bio->bi_rw = READ;
4254        read_bio->bi_flags &= ~(BIO_POOL_MASK - 1);
4255        read_bio->bi_flags |= 1 << BIO_UPTODATE;
4256        read_bio->bi_vcnt = 0;
4257        read_bio->bi_idx = 0;
4258        read_bio->bi_size = 0;
4259        r10_bio->master_bio = read_bio;
4260        r10_bio->read_slot = r10_bio->devs[r10_bio->read_slot].devnum;
4261
4262        /* Now find the locations in the new layout */
4263        __raid10_find_phys(&conf->geo, r10_bio);
4264
4265        blist = read_bio;
4266        read_bio->bi_next = NULL;
4267
4268        for (s = 0; s < conf->copies*2; s++) {
4269                struct bio *b;
4270                int d = r10_bio->devs[s/2].devnum;
4271                struct md_rdev *rdev2;
4272                if (s&1) {
4273                        rdev2 = conf->mirrors[d].replacement;
4274                        b = r10_bio->devs[s/2].repl_bio;
4275                } else {
4276                        rdev2 = conf->mirrors[d].rdev;
4277                        b = r10_bio->devs[s/2].bio;
4278                }
4279                if (!rdev2 || test_bit(Faulty, &rdev2->flags))
4280                        continue;
4281                b->bi_bdev = rdev2->bdev;
4282                b->bi_sector = r10_bio->devs[s/2].addr + rdev2->new_data_offset;
4283                b->bi_private = r10_bio;
4284                b->bi_end_io = end_reshape_write;
4285                b->bi_rw = WRITE;
4286                b->bi_flags &= ~(BIO_POOL_MASK - 1);
4287                b->bi_flags |= 1 << BIO_UPTODATE;
4288                b->bi_next = blist;
4289                b->bi_vcnt = 0;
4290                b->bi_idx = 0;
4291                b->bi_size = 0;
4292                blist = b;
4293        }
4294
4295        /* Now add as many pages as possible to all of these bios. */
4296
4297        nr_sectors = 0;
4298        for (s = 0 ; s < max_sectors; s += PAGE_SIZE >> 9) {
4299                struct page *page = r10_bio->devs[0].bio->bi_io_vec[s/(PAGE_SIZE>>9)].bv_page;
4300                int len = (max_sectors - s) << 9;
4301                if (len > PAGE_SIZE)
4302                        len = PAGE_SIZE;
4303                for (bio = blist; bio ; bio = bio->bi_next) {
4304                        struct bio *bio2;
4305                        if (bio_add_page(bio, page, len, 0))
4306                                continue;
4307
4308                        /* Didn't fit, must stop */
4309                        for (bio2 = blist;
4310                             bio2 && bio2 != bio;
4311                             bio2 = bio2->bi_next) {
4312                                /* Remove last page from this bio */
4313                                bio2->bi_vcnt--;
4314                                bio2->bi_size -= len;
4315                                bio2->bi_flags &= ~(1<<BIO_SEG_VALID);
4316                        }
4317                        goto bio_full;
4318                }
4319                sector_nr += len >> 9;
4320                nr_sectors += len >> 9;
4321        }
4322bio_full:
4323        r10_bio->sectors = nr_sectors;
4324
4325        /* Now submit the read */
4326        md_sync_acct(read_bio->bi_bdev, r10_bio->sectors);
4327        atomic_inc(&r10_bio->remaining);
4328        read_bio->bi_next = NULL;
4329        generic_make_request(read_bio);
4330        sector_nr += nr_sectors;
4331        sectors_done += nr_sectors;
4332        if (sector_nr <= last)
4333                goto read_more;
4334
4335        /* Now that we have done the whole section we can
4336         * update reshape_progress
4337         */
4338        if (mddev->reshape_backwards)
4339                conf->reshape_progress -= sectors_done;
4340        else
4341                conf->reshape_progress += sectors_done;
4342
4343        return sectors_done;
4344}
4345
4346static void end_reshape_request(struct r10bio *r10_bio);
4347static int handle_reshape_read_error(struct mddev *mddev,
4348                                     struct r10bio *r10_bio);
4349static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio)
4350{
4351        /* Reshape read completed.  Hopefully we have a block
4352         * to write out.
4353         * If we got a read error then we do sync 1-page reads from
4354         * elsewhere until we find the data - or give up.
4355         */
4356        struct r10conf *conf = mddev->private;
4357        int s;
4358
4359        if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
4360                if (handle_reshape_read_error(mddev, r10_bio) < 0) {
4361                        /* Reshape has been aborted */
4362                        md_done_sync(mddev, r10_bio->sectors, 0);
4363                        return;
4364                }
4365
4366        /* We definitely have the data in the pages, schedule the
4367         * writes.
4368         */
4369        atomic_set(&r10_bio->remaining, 1);
4370        for (s = 0; s < conf->copies*2; s++) {
4371                struct bio *b;
4372                int d = r10_bio->devs[s/2].devnum;
4373                struct md_rdev *rdev;
4374                if (s&1) {
4375                        rdev = conf->mirrors[d].replacement;
4376                        b = r10_bio->devs[s/2].repl_bio;
4377                } else {
4378                        rdev = conf->mirrors[d].rdev;
4379                        b = r10_bio->devs[s/2].bio;
4380                }
4381                if (!rdev || test_bit(Faulty, &rdev->flags))
4382                        continue;
4383                atomic_inc(&rdev->nr_pending);
4384                md_sync_acct(b->bi_bdev, r10_bio->sectors);
4385                atomic_inc(&r10_bio->remaining);
4386                b->bi_next = NULL;
4387                generic_make_request(b);
4388        }
4389        end_reshape_request(r10_bio);
4390}
4391
4392static void end_reshape(struct r10conf *conf)
4393{
4394        if (test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery))
4395                return;
4396
4397        spin_lock_irq(&conf->device_lock);
4398        conf->prev = conf->geo;
4399        md_finish_reshape(conf->mddev);
4400        smp_wmb();
4401        conf->reshape_progress = MaxSector;
4402        spin_unlock_irq(&conf->device_lock);
4403
4404        /* read-ahead size must cover two whole stripes, which is
4405         * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4406         */
4407        if (conf->mddev->queue) {
4408                int stripe = conf->geo.raid_disks *
4409                        ((conf->mddev->chunk_sectors << 9) / PAGE_SIZE);
4410                stripe /= conf->geo.near_copies;
4411                if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4412                        conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4413        }
4414        conf->fullsync = 0;
4415}
4416
4417
4418static int handle_reshape_read_error(struct mddev *mddev,
4419                                     struct r10bio *r10_bio)
4420{
4421        /* Use sync reads to get the blocks from somewhere else */
4422        int sectors = r10_bio->sectors;
4423        struct r10conf *conf = mddev->private;
4424        struct {
4425                struct r10bio r10_bio;
4426                struct r10dev devs[conf->copies];
4427        } on_stack;
4428        struct r10bio *r10b = &on_stack.r10_bio;
4429        int slot = 0;
4430        int idx = 0;
4431        struct bio_vec *bvec = r10_bio->master_bio->bi_io_vec;
4432
4433        r10b->sector = r10_bio->sector;
4434        __raid10_find_phys(&conf->prev, r10b);
4435
4436        while (sectors) {
4437                int s = sectors;
4438                int success = 0;
4439                int first_slot = slot;
4440
4441                if (s > (PAGE_SIZE >> 9))
4442                        s = PAGE_SIZE >> 9;
4443
4444                while (!success) {
4445                        int d = r10b->devs[slot].devnum;
4446                        struct md_rdev *rdev = conf->mirrors[d].rdev;
4447                        sector_t addr;
4448                        if (rdev == NULL ||
4449                            test_bit(Faulty, &rdev->flags) ||
4450                            !test_bit(In_sync, &rdev->flags))
4451                                goto failed;
4452
4453                        addr = r10b->devs[slot].addr + idx * PAGE_SIZE;
4454                        success = sync_page_io(rdev,
4455                                               addr,
4456                                               s << 9,
4457                                               bvec[idx].bv_page,
4458                                               READ, false);
4459                        if (success)
4460                                break;
4461                failed:
4462                        slot++;
4463                        if (slot >= conf->copies)
4464                                slot = 0;
4465                        if (slot == first_slot)
4466                                break;
4467                }
4468                if (!success) {
4469                        /* couldn't read this block, must give up */
4470                        set_bit(MD_RECOVERY_INTR,
4471                                &mddev->recovery);
4472                        return -EIO;
4473                }
4474                sectors -= s;
4475                idx++;
4476        }
4477        return 0;
4478}
4479
4480static void end_reshape_write(struct bio *bio, int error)
4481{
4482        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
4483        struct r10bio *r10_bio = bio->bi_private;
4484        struct mddev *mddev = r10_bio->mddev;
4485        struct r10conf *conf = mddev->private;
4486        int d;
4487        int slot;
4488        int repl;
4489        struct md_rdev *rdev = NULL;
4490
4491        d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
4492        if (repl)
4493                rdev = conf->mirrors[d].replacement;
4494        if (!rdev) {
4495                smp_mb();
4496                rdev = conf->mirrors[d].rdev;
4497        }
4498
4499        if (!uptodate) {
4500                /* FIXME should record badblock */
4501                md_error(mddev, rdev);
4502        }
4503
4504        rdev_dec_pending(rdev, mddev);
4505        end_reshape_request(r10_bio);
4506}
4507
4508static void end_reshape_request(struct r10bio *r10_bio)
4509{
4510        if (!atomic_dec_and_test(&r10_bio->remaining))
4511                return;
4512        md_done_sync(r10_bio->mddev, r10_bio->sectors, 1);
4513        bio_put(r10_bio->master_bio);
4514        put_buf(r10_bio);
4515}
4516
4517static void raid10_finish_reshape(struct mddev *mddev)
4518{
4519        struct r10conf *conf = mddev->private;
4520
4521        if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
4522                return;
4523
4524        if (mddev->delta_disks > 0) {
4525                sector_t size = raid10_size(mddev, 0, 0);
4526                md_set_array_sectors(mddev, size);
4527                if (mddev->recovery_cp > mddev->resync_max_sectors) {
4528                        mddev->recovery_cp = mddev->resync_max_sectors;
4529                        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4530                }
4531                mddev->resync_max_sectors = size;
4532                set_capacity(mddev->gendisk, mddev->array_sectors);
4533                revalidate_disk(mddev->gendisk);
4534        } else {
4535                int d;
4536                for (d = conf->geo.raid_disks ;
4537                     d < conf->geo.raid_disks - mddev->delta_disks;
4538                     d++) {
4539                        struct md_rdev *rdev = conf->mirrors[d].rdev;
4540                        if (rdev)
4541                                clear_bit(In_sync, &rdev->flags);
4542                        rdev = conf->mirrors[d].replacement;
4543                        if (rdev)
4544                                clear_bit(In_sync, &rdev->flags);
4545                }
4546        }
4547        mddev->layout = mddev->new_layout;
4548        mddev->chunk_sectors = 1 << conf->geo.chunk_shift;
4549        mddev->reshape_position = MaxSector;
4550        mddev->delta_disks = 0;
4551        mddev->reshape_backwards = 0;
4552}
4553
4554static struct md_personality raid10_personality =
4555{
4556        .name           = "raid10",
4557        .level          = 10,
4558        .owner          = THIS_MODULE,
4559        .make_request   = make_request,
4560        .run            = run,
4561        .stop           = stop,
4562        .status         = status,
4563        .error_handler  = error,
4564        .hot_add_disk   = raid10_add_disk,
4565        .hot_remove_disk= raid10_remove_disk,
4566        .spare_active   = raid10_spare_active,
4567        .sync_request   = sync_request,
4568        .quiesce        = raid10_quiesce,
4569        .size           = raid10_size,
4570        .resize         = raid10_resize,
4571        .takeover       = raid10_takeover,
4572        .check_reshape  = raid10_check_reshape,
4573        .start_reshape  = raid10_start_reshape,
4574        .finish_reshape = raid10_finish_reshape,
4575};
4576
4577static int __init raid_init(void)
4578{
4579        return register_md_personality(&raid10_personality);
4580}
4581
4582static void raid_exit(void)
4583{
4584        unregister_md_personality(&raid10_personality);
4585}
4586
4587module_init(raid_init);
4588module_exit(raid_exit);
4589MODULE_LICENSE("GPL");
4590MODULE_DESCRIPTION("RAID10 (striped mirror) personality for MD");
4591MODULE_ALIAS("md-personality-9"); /* RAID10 */
4592MODULE_ALIAS("md-raid10");
4593MODULE_ALIAS("md-level-10");
4594
4595module_param(max_queued_requests, int, S_IRUGO|S_IWUSR);
4596
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