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(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                        if (unlikely((bio->bi_rw & REQ_DISCARD) &&
 915                            !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
 916                                /* Just ignore it */
 917                                bio_endio(bio, 0);
 918                        else
 919                                generic_make_request(bio);
 920                        bio = next;
 921                }
 922        } else
 923                spin_unlock_irq(&conf->device_lock);
 924}
 925
 926/* Barriers....
 927 * Sometimes we need to suspend IO while we do something else,
 928 * either some resync/recovery, or reconfigure the array.
 929 * To do this we raise a 'barrier'.
 930 * The 'barrier' is a counter that can be raised multiple times
 931 * to count how many activities are happening which preclude
 932 * normal IO.
 933 * We can only raise the barrier if there is no pending IO.
 934 * i.e. if nr_pending == 0.
 935 * We choose only to raise the barrier if no-one is waiting for the
 936 * barrier to go down.  This means that as soon as an IO request
 937 * is ready, no other operations which require a barrier will start
 938 * until the IO request has had a chance.
 939 *
 940 * So: regular IO calls 'wait_barrier'.  When that returns there
 941 *    is no backgroup IO happening,  It must arrange to call
 942 *    allow_barrier when it has finished its IO.
 943 * backgroup IO calls must call raise_barrier.  Once that returns
 944 *    there is no normal IO happeing.  It must arrange to call
 945 *    lower_barrier when the particular background IO completes.
 946 */
 947
 948static void raise_barrier(struct r10conf *conf, int force)
 949{
 950        BUG_ON(force && !conf->barrier);
 951        spin_lock_irq(&conf->resync_lock);
 952
 953        /* Wait until no block IO is waiting (unless 'force') */
 954        wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
 955                            conf->resync_lock);
 956
 957        /* block any new IO from starting */
 958        conf->barrier++;
 959
 960        /* Now wait for all pending IO to complete */
 961        wait_event_lock_irq(conf->wait_barrier,
 962                            !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 963                            conf->resync_lock);
 964
 965        spin_unlock_irq(&conf->resync_lock);
 966}
 967
 968static void lower_barrier(struct r10conf *conf)
 969{
 970        unsigned long flags;
 971        spin_lock_irqsave(&conf->resync_lock, flags);
 972        conf->barrier--;
 973        spin_unlock_irqrestore(&conf->resync_lock, flags);
 974        wake_up(&conf->wait_barrier);
 975}
 976
 977static void wait_barrier(struct r10conf *conf)
 978{
 979        spin_lock_irq(&conf->resync_lock);
 980        if (conf->barrier) {
 981                conf->nr_waiting++;
 982                /* Wait for the barrier to drop.
 983                 * However if there are already pending
 984                 * requests (preventing the barrier from
 985                 * rising completely), and the
 986                 * pre-process bio queue isn't empty,
 987                 * then don't wait, as we need to empty
 988                 * that queue to get the nr_pending
 989                 * count down.
 990                 */
 991                wait_event_lock_irq(conf->wait_barrier,
 992                                    !conf->barrier ||
 993                                    (conf->nr_pending &&
 994                                     current->bio_list &&
 995                                     !bio_list_empty(current->bio_list)),
 996                                    conf->resync_lock);
 997                conf->nr_waiting--;
 998        }
 999        conf->nr_pending++;
1000        spin_unlock_irq(&conf->resync_lock);
1001}
1002
1003static void allow_barrier(struct r10conf *conf)
1004{
1005        unsigned long flags;
1006        spin_lock_irqsave(&conf->resync_lock, flags);
1007        conf->nr_pending--;
1008        spin_unlock_irqrestore(&conf->resync_lock, flags);
1009        wake_up(&conf->wait_barrier);
1010}
1011
1012static void freeze_array(struct r10conf *conf)
1013{
1014        /* stop syncio and normal IO and wait for everything to
1015         * go quiet.
1016         * We increment barrier and nr_waiting, and then
1017         * wait until nr_pending match nr_queued+1
1018         * This is called in the context of one normal IO request
1019         * that has failed. Thus any sync request that might be pending
1020         * will be blocked by nr_pending, and we need to wait for
1021         * pending IO requests to complete or be queued for re-try.
1022         * Thus the number queued (nr_queued) plus this request (1)
1023         * must match the number of pending IOs (nr_pending) before
1024         * we continue.
1025         */
1026        spin_lock_irq(&conf->resync_lock);
1027        conf->barrier++;
1028        conf->nr_waiting++;
1029        wait_event_lock_irq_cmd(conf->wait_barrier,
1030                                conf->nr_pending == conf->nr_queued+1,
1031                                conf->resync_lock,
1032                                flush_pending_writes(conf));
1033
1034        spin_unlock_irq(&conf->resync_lock);
1035}
1036
1037static void unfreeze_array(struct r10conf *conf)
1038{
1039        /* reverse the effect of the freeze */
1040        spin_lock_irq(&conf->resync_lock);
1041        conf->barrier--;
1042        conf->nr_waiting--;
1043        wake_up(&conf->wait_barrier);
1044        spin_unlock_irq(&conf->resync_lock);
1045}
1046
1047static sector_t choose_data_offset(struct r10bio *r10_bio,
1048                                   struct md_rdev *rdev)
1049{
1050        if (!test_bit(MD_RECOVERY_RESHAPE, &rdev->mddev->recovery) ||
1051            test_bit(R10BIO_Previous, &r10_bio->state))
1052                return rdev->data_offset;
1053        else
1054                return rdev->new_data_offset;
1055}
1056
1057struct raid10_plug_cb {
1058        struct blk_plug_cb      cb;
1059        struct bio_list         pending;
1060        int                     pending_cnt;
1061};
1062
1063static void raid10_unplug(struct blk_plug_cb *cb, bool from_schedule)
1064{
1065        struct raid10_plug_cb *plug = container_of(cb, struct raid10_plug_cb,
1066                                                   cb);
1067        struct mddev *mddev = plug->cb.data;
1068        struct r10conf *conf = mddev->private;
1069        struct bio *bio;
1070
1071        if (from_schedule || current->bio_list) {
1072                spin_lock_irq(&conf->device_lock);
1073                bio_list_merge(&conf->pending_bio_list, &plug->pending);
1074                conf->pending_count += plug->pending_cnt;
1075                spin_unlock_irq(&conf->device_lock);
1076                md_wakeup_thread(mddev->thread);
1077                kfree(plug);
1078                return;
1079        }
1080
1081        /* we aren't scheduling, so we can do the write-out directly. */
1082        bio = bio_list_get(&plug->pending);
1083        bitmap_unplug(mddev->bitmap);
1084        wake_up(&conf->wait_barrier);
1085
1086        while (bio) { /* submit pending writes */
1087                struct bio *next = bio->bi_next;
1088                bio->bi_next = NULL;
1089                generic_make_request(bio);
1090                bio = next;
1091        }
1092        kfree(plug);
1093}
1094
1095static void make_request(struct mddev *mddev, struct bio * bio)
1096{
1097        struct r10conf *conf = mddev->private;
1098        struct r10bio *r10_bio;
1099        struct bio *read_bio;
1100        int i;
1101        sector_t chunk_mask = (conf->geo.chunk_mask & conf->prev.chunk_mask);
1102        int chunk_sects = chunk_mask + 1;
1103        const int rw = bio_data_dir(bio);
1104        const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
1105        const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
1106        const unsigned long do_discard = (bio->bi_rw
1107                                          & (REQ_DISCARD | REQ_SECURE));
1108        unsigned long flags;
1109        struct md_rdev *blocked_rdev;
1110        struct blk_plug_cb *cb;
1111        struct raid10_plug_cb *plug = NULL;
1112        int sectors_handled;
1113        int max_sectors;
1114        int sectors;
1115
1116        if (unlikely(bio->bi_rw & REQ_FLUSH)) {
1117                md_flush_request(mddev, bio);
1118                return;
1119        }
1120
1121        /* If this request crosses a chunk boundary, we need to
1122         * split it.  This will only happen for 1 PAGE (or less) requests.
1123         */
1124        if (unlikely((bio->bi_sector & chunk_mask) + (bio->bi_size >> 9)
1125                     > chunk_sects
1126                     && (conf->geo.near_copies < conf->geo.raid_disks
1127                         || conf->prev.near_copies < conf->prev.raid_disks))) {
1128                struct bio_pair *bp;
1129                /* Sanity check -- queue functions should prevent this happening */
1130                if ((bio->bi_vcnt != 1 && bio->bi_vcnt != 0) ||
1131                    bio->bi_idx != 0)
1132                        goto bad_map;
1133                /* This is a one page bio that upper layers
1134                 * refuse to split for us, so we need to split it.
1135                 */
1136                bp = bio_split(bio,
1137                               chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
1138
1139                /* Each of these 'make_request' calls will call 'wait_barrier'.
1140                 * If the first succeeds but the second blocks due to the resync
1141                 * thread raising the barrier, we will deadlock because the
1142                 * IO to the underlying device will be queued in generic_make_request
1143                 * and will never complete, so will never reduce nr_pending.
1144                 * So increment nr_waiting here so no new raise_barriers will
1145                 * succeed, and so the second wait_barrier cannot block.
1146                 */
1147                spin_lock_irq(&conf->resync_lock);
1148                conf->nr_waiting++;
1149                spin_unlock_irq(&conf->resync_lock);
1150
1151                make_request(mddev, &bp->bio1);
1152                make_request(mddev, &bp->bio2);
1153
1154                spin_lock_irq(&conf->resync_lock);
1155                conf->nr_waiting--;
1156                wake_up(&conf->wait_barrier);
1157                spin_unlock_irq(&conf->resync_lock);
1158
1159                bio_pair_release(bp);
1160                return;
1161        bad_map:
1162                printk("md/raid10:%s: make_request bug: can't convert block across chunks"
1163                       " or bigger than %dk %llu %d\n", mdname(mddev), chunk_sects/2,
1164                       (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
1165
1166                bio_io_error(bio);
1167                return;
1168        }
1169
1170        md_write_start(mddev, bio);
1171
1172        /*
1173         * Register the new request and wait if the reconstruction
1174         * thread has put up a bar for new requests.
1175         * Continue immediately if no resync is active currently.
1176         */
1177        wait_barrier(conf);
1178
1179        sectors = bio->bi_size >> 9;
1180        while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
1181            bio->bi_sector < conf->reshape_progress &&
1182            bio->bi_sector + sectors > conf->reshape_progress) {
1183                /* IO spans the reshape position.  Need to wait for
1184                 * reshape to pass
1185                 */
1186                allow_barrier(conf);
1187                wait_event(conf->wait_barrier,
1188                           conf->reshape_progress <= bio->bi_sector ||
1189                           conf->reshape_progress >= bio->bi_sector + sectors);
1190                wait_barrier(conf);
1191        }
1192        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
1193            bio_data_dir(bio) == WRITE &&
1194            (mddev->reshape_backwards
1195             ? (bio->bi_sector < conf->reshape_safe &&
1196                bio->bi_sector + sectors > conf->reshape_progress)
1197             : (bio->bi_sector + sectors > conf->reshape_safe &&
1198                bio->bi_sector < conf->reshape_progress))) {
1199                /* Need to update reshape_position in metadata */
1200                mddev->reshape_position = conf->reshape_progress;
1201                set_bit(MD_CHANGE_DEVS, &mddev->flags);
1202                set_bit(MD_CHANGE_PENDING, &mddev->flags);
1203                md_wakeup_thread(mddev->thread);
1204                wait_event(mddev->sb_wait,
1205                           !test_bit(MD_CHANGE_PENDING, &mddev->flags));
1206
1207                conf->reshape_safe = mddev->reshape_position;
1208        }
1209
1210        r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1211
1212        r10_bio->master_bio = bio;
1213        r10_bio->sectors = sectors;
1214
1215        r10_bio->mddev = mddev;
1216        r10_bio->sector = bio->bi_sector;
1217        r10_bio->state = 0;
1218
1219        /* We might need to issue multiple reads to different
1220         * devices if there are bad blocks around, so we keep
1221         * track of the number of reads in bio->bi_phys_segments.
1222         * If this is 0, there is only one r10_bio and no locking
1223         * will be needed when the request completes.  If it is
1224         * non-zero, then it is the number of not-completed requests.
1225         */
1226        bio->bi_phys_segments = 0;
1227        clear_bit(BIO_SEG_VALID, &bio->bi_flags);
1228
1229        if (rw == READ) {
1230                /*
1231                 * read balancing logic:
1232                 */
1233                struct md_rdev *rdev;
1234                int slot;
1235
1236read_again:
1237                rdev = read_balance(conf, r10_bio, &max_sectors);
1238                if (!rdev) {
1239                        raid_end_bio_io(r10_bio);
1240                        return;
1241                }
1242                slot = r10_bio->read_slot;
1243
1244                read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1245                md_trim_bio(read_bio, r10_bio->sector - bio->bi_sector,
1246                            max_sectors);
1247
1248                r10_bio->devs[slot].bio = read_bio;
1249                r10_bio->devs[slot].rdev = rdev;
1250
1251                read_bio->bi_sector = r10_bio->devs[slot].addr +
1252                        choose_data_offset(r10_bio, rdev);
1253                read_bio->bi_bdev = rdev->bdev;
1254                read_bio->bi_end_io = raid10_end_read_request;
1255                read_bio->bi_rw = READ | do_sync;
1256                read_bio->bi_private = r10_bio;
1257
1258                if (max_sectors < r10_bio->sectors) {
1259                        /* Could not read all from this device, so we will
1260                         * need another r10_bio.
1261                         */
1262                        sectors_handled = (r10_bio->sectors + max_sectors
1263                                           - bio->bi_sector);
1264                        r10_bio->sectors = max_sectors;
1265                        spin_lock_irq(&conf->device_lock);
1266                        if (bio->bi_phys_segments == 0)
1267                                bio->bi_phys_segments = 2;
1268                        else
1269                                bio->bi_phys_segments++;
1270                        spin_unlock(&conf->device_lock);
1271                        /* Cannot call generic_make_request directly
1272                         * as that will be queued in __generic_make_request
1273                         * and subsequent mempool_alloc might block
1274                         * waiting for it.  so hand bio over to raid10d.
1275                         */
1276                        reschedule_retry(r10_bio);
1277
1278                        r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1279
1280                        r10_bio->master_bio = bio;
1281                        r10_bio->sectors = ((bio->bi_size >> 9)
1282                                            - sectors_handled);
1283                        r10_bio->state = 0;
1284                        r10_bio->mddev = mddev;
1285                        r10_bio->sector = bio->bi_sector + sectors_handled;
1286                        goto read_again;
1287                } else
1288                        generic_make_request(read_bio);
1289                return;
1290        }
1291
1292        /*
1293         * WRITE:
1294         */
1295        if (conf->pending_count >= max_queued_requests) {
1296                md_wakeup_thread(mddev->thread);
1297                wait_event(conf->wait_barrier,
1298                           conf->pending_count < max_queued_requests);
1299        }
1300        /* first select target devices under rcu_lock and
1301         * inc refcount on their rdev.  Record them by setting
1302         * bios[x] to bio
1303         * If there are known/acknowledged bad blocks on any device
1304         * on which we have seen a write error, we want to avoid
1305         * writing to those blocks.  This potentially requires several
1306         * writes to write around the bad blocks.  Each set of writes
1307         * gets its own r10_bio with a set of bios attached.  The number
1308         * of r10_bios is recored in bio->bi_phys_segments just as with
1309         * the read case.
1310         */
1311
1312        r10_bio->read_slot = -1; /* make sure repl_bio gets freed */
1313        raid10_find_phys(conf, r10_bio);
1314retry_write:
1315        blocked_rdev = NULL;
1316        rcu_read_lock();
1317        max_sectors = r10_bio->sectors;
1318
1319        for (i = 0;  i < conf->copies; i++) {
1320                int d = r10_bio->devs[i].devnum;
1321                struct md_rdev *rdev = rcu_dereference(conf->mirrors[d].rdev);
1322                struct md_rdev *rrdev = rcu_dereference(
1323                        conf->mirrors[d].replacement);
1324                if (rdev == rrdev)
1325                        rrdev = NULL;
1326                if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
1327                        atomic_inc(&rdev->nr_pending);
1328                        blocked_rdev = rdev;
1329                        break;
1330                }
1331                if (rrdev && unlikely(test_bit(Blocked, &rrdev->flags))) {
1332                        atomic_inc(&rrdev->nr_pending);
1333                        blocked_rdev = rrdev;
1334                        break;
1335                }
1336                if (rdev && (test_bit(Faulty, &rdev->flags)
1337                             || test_bit(Unmerged, &rdev->flags)))
1338                        rdev = NULL;
1339                if (rrdev && (test_bit(Faulty, &rrdev->flags)
1340                              || test_bit(Unmerged, &rrdev->flags)))
1341                        rrdev = NULL;
1342
1343                r10_bio->devs[i].bio = NULL;
1344                r10_bio->devs[i].repl_bio = NULL;
1345
1346                if (!rdev && !rrdev) {
1347                        set_bit(R10BIO_Degraded, &r10_bio->state);
1348                        continue;
1349                }
1350                if (rdev && test_bit(WriteErrorSeen, &rdev->flags)) {
1351                        sector_t first_bad;
1352                        sector_t dev_sector = r10_bio->devs[i].addr;
1353                        int bad_sectors;
1354                        int is_bad;
1355
1356                        is_bad = is_badblock(rdev, dev_sector,
1357                                             max_sectors,
1358                                             &first_bad, &bad_sectors);
1359                        if (is_bad < 0) {
1360                                /* Mustn't write here until the bad block
1361                                 * is acknowledged
1362                                 */
1363                                atomic_inc(&rdev->nr_pending);
1364                                set_bit(BlockedBadBlocks, &rdev->flags);
1365                                blocked_rdev = rdev;
1366                                break;
1367                        }
1368                        if (is_bad && first_bad <= dev_sector) {
1369                                /* Cannot write here at all */
1370                                bad_sectors -= (dev_sector - first_bad);
1371                                if (bad_sectors < max_sectors)
1372                                        /* Mustn't write more than bad_sectors
1373                                         * to other devices yet
1374                                         */
1375                                        max_sectors = bad_sectors;
1376                                /* We don't set R10BIO_Degraded as that
1377                                 * only applies if the disk is missing,
1378                                 * so it might be re-added, and we want to
1379                                 * know to recover this chunk.
1380                                 * In this case the device is here, and the
1381                                 * fact that this chunk is not in-sync is
1382                                 * recorded in the bad block log.
1383                                 */
1384                                continue;
1385                        }
1386                        if (is_bad) {
1387                                int good_sectors = first_bad - dev_sector;
1388                                if (good_sectors < max_sectors)
1389                                        max_sectors = good_sectors;
1390                        }
1391                }
1392                if (rdev) {
1393                        r10_bio->devs[i].bio = bio;
1394                        atomic_inc(&rdev->nr_pending);
1395                }
1396                if (rrdev) {
1397                        r10_bio->devs[i].repl_bio = bio;
1398                        atomic_inc(&rrdev->nr_pending);
1399                }
1400        }
1401        rcu_read_unlock();
1402
1403        if (unlikely(blocked_rdev)) {
1404                /* Have to wait for this device to get unblocked, then retry */
1405                int j;
1406                int d;
1407
1408                for (j = 0; j < i; j++) {
1409                        if (r10_bio->devs[j].bio) {
1410                                d = r10_bio->devs[j].devnum;
1411                                rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1412                        }
1413                        if (r10_bio->devs[j].repl_bio) {
1414                                struct md_rdev *rdev;
1415                                d = r10_bio->devs[j].devnum;
1416                                rdev = conf->mirrors[d].replacement;
1417                                if (!rdev) {
1418                                        /* Race with remove_disk */
1419                                        smp_mb();
1420                                        rdev = conf->mirrors[d].rdev;
1421                                }
1422                                rdev_dec_pending(rdev, mddev);
1423                        }
1424                }
1425                allow_barrier(conf);
1426                md_wait_for_blocked_rdev(blocked_rdev, mddev);
1427                wait_barrier(conf);
1428                goto retry_write;
1429        }
1430
1431        if (max_sectors < r10_bio->sectors) {
1432                /* We are splitting this into multiple parts, so
1433                 * we need to prepare for allocating another r10_bio.
1434                 */
1435                r10_bio->sectors = max_sectors;
1436                spin_lock_irq(&conf->device_lock);
1437                if (bio->bi_phys_segments == 0)
1438                        bio->bi_phys_segments = 2;
1439                else
1440                        bio->bi_phys_segments++;
1441                spin_unlock_irq(&conf->device_lock);
1442        }
1443        sectors_handled = r10_bio->sector + max_sectors - bio->bi_sector;
1444
1445        atomic_set(&r10_bio->remaining, 1);
1446        bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
1447
1448        for (i = 0; i < conf->copies; i++) {
1449                struct bio *mbio;
1450                int d = r10_bio->devs[i].devnum;
1451                if (r10_bio->devs[i].bio) {
1452                        struct md_rdev *rdev = conf->mirrors[d].rdev;
1453                        mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1454                        md_trim_bio(mbio, r10_bio->sector - bio->bi_sector,
1455                                    max_sectors);
1456                        r10_bio->devs[i].bio = mbio;
1457
1458                        mbio->bi_sector = (r10_bio->devs[i].addr+
1459                                           choose_data_offset(r10_bio,
1460                                                              rdev));
1461                        mbio->bi_bdev = rdev->bdev;
1462                        mbio->bi_end_io = raid10_end_write_request;
1463                        mbio->bi_rw = WRITE | do_sync | do_fua | do_discard;
1464                        mbio->bi_private = r10_bio;
1465
1466                        atomic_inc(&r10_bio->remaining);
1467
1468                        cb = blk_check_plugged(raid10_unplug, mddev,
1469                                               sizeof(*plug));
1470                        if (cb)
1471                                plug = container_of(cb, struct raid10_plug_cb,
1472                                                    cb);
1473                        else
1474                                plug = NULL;
1475                        spin_lock_irqsave(&conf->device_lock, flags);
1476                        if (plug) {
1477                                bio_list_add(&plug->pending, mbio);
1478                                plug->pending_cnt++;
1479                        } else {
1480                                bio_list_add(&conf->pending_bio_list, mbio);
1481                                conf->pending_count++;
1482                        }
1483                        spin_unlock_irqrestore(&conf->device_lock, flags);
1484                        if (!plug)
1485                                md_wakeup_thread(mddev->thread);
1486                }
1487
1488                if (r10_bio->devs[i].repl_bio) {
1489                        struct md_rdev *rdev = conf->mirrors[d].replacement;
1490                        if (rdev == NULL) {
1491                                /* Replacement just got moved to main 'rdev' */
1492                                smp_mb();
1493                                rdev = conf->mirrors[d].rdev;
1494                        }
1495                        mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1496                        md_trim_bio(mbio, r10_bio->sector - bio->bi_sector,
1497                                    max_sectors);
1498                        r10_bio->devs[i].repl_bio = mbio;
1499
1500                        mbio->bi_sector = (r10_bio->devs[i].addr +
1501                                           choose_data_offset(
1502                                                   r10_bio, rdev));
1503                        mbio->bi_bdev = rdev->bdev;
1504                        mbio->bi_end_io = raid10_end_write_request;
1505                        mbio->bi_rw = WRITE | do_sync | do_fua | do_discard;
1506                        mbio->bi_private = r10_bio;
1507
1508                        atomic_inc(&r10_bio->remaining);
1509                        spin_lock_irqsave(&conf->device_lock, flags);
1510                        bio_list_add(&conf->pending_bio_list, mbio);
1511                        conf->pending_count++;
1512                        spin_unlock_irqrestore(&conf->device_lock, flags);
1513                        if (!mddev_check_plugged(mddev))
1514                                md_wakeup_thread(mddev->thread);
1515                }
1516        }
1517
1518        /* Don't remove the bias on 'remaining' (one_write_done) until
1519         * after checking if we need to go around again.
1520         */
1521
1522        if (sectors_handled < (bio->bi_size >> 9)) {
1523                one_write_done(r10_bio);
1524                /* We need another r10_bio.  It has already been counted
1525                 * in bio->bi_phys_segments.
1526                 */
1527                r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
1528
1529                r10_bio->master_bio = bio;
1530                r10_bio->sectors = (bio->bi_size >> 9) - sectors_handled;
1531
1532                r10_bio->mddev = mddev;
1533                r10_bio->sector = bio->bi_sector + sectors_handled;
1534                r10_bio->state = 0;
1535                goto retry_write;
1536        }
1537        one_write_done(r10_bio);
1538
1539        /* In case raid10d snuck in to freeze_array */
1540        wake_up(&conf->wait_barrier);
1541}
1542
1543static void status(struct seq_file *seq, struct mddev *mddev)
1544{
1545        struct r10conf *conf = mddev->private;
1546        int i;
1547
1548        if (conf->geo.near_copies < conf->geo.raid_disks)
1549                seq_printf(seq, " %dK chunks", mddev->chunk_sectors / 2);
1550        if (conf->geo.near_copies > 1)
1551                seq_printf(seq, " %d near-copies", conf->geo.near_copies);
1552        if (conf->geo.far_copies > 1) {
1553                if (conf->geo.far_offset)
1554                        seq_printf(seq, " %d offset-copies", conf->geo.far_copies);
1555                else
1556                        seq_printf(seq, " %d far-copies", conf->geo.far_copies);
1557        }
1558        seq_printf(seq, " [%d/%d] [", conf->geo.raid_disks,
1559                                        conf->geo.raid_disks - mddev->degraded);
1560        for (i = 0; i < conf->geo.raid_disks; i++)
1561                seq_printf(seq, "%s",
1562                              conf->mirrors[i].rdev &&
1563                              test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
1564        seq_printf(seq, "]");
1565}
1566
1567/* check if there are enough drives for
1568 * every block to appear on atleast one.
1569 * Don't consider the device numbered 'ignore'
1570 * as we might be about to remove it.
1571 */
1572static int _enough(struct r10conf *conf, struct geom *geo, int ignore)
1573{
1574        int first = 0;
1575
1576        do {
1577                int n = conf->copies;
1578                int cnt = 0;
1579                int this = first;
1580                while (n--) {
1581                        if (conf->mirrors[this].rdev &&
1582                            this != ignore)
1583                                cnt++;
1584                        this = (this+1) % geo->raid_disks;
1585                }
1586                if (cnt == 0)
1587                        return 0;
1588                first = (first + geo->near_copies) % geo->raid_disks;
1589        } while (first != 0);
1590        return 1;
1591}
1592
1593static int enough(struct r10conf *conf, int ignore)
1594{
1595        return _enough(conf, &conf->geo, ignore) &&
1596                _enough(conf, &conf->prev, ignore);
1597}
1598
1599static void error(struct mddev *mddev, struct md_rdev *rdev)
1600{
1601        char b[BDEVNAME_SIZE];
1602        struct r10conf *conf = mddev->private;
1603
1604        /*
1605         * If it is not operational, then we have already marked it as dead
1606         * else if it is the last working disks, ignore the error, let the
1607         * next level up know.
1608         * else mark the drive as failed
1609         */
1610        if (test_bit(In_sync, &rdev->flags)
1611            && !enough(conf, rdev->raid_disk))
1612                /*
1613                 * Don't fail the drive, just return an IO error.
1614                 */
1615                return;
1616        if (test_and_clear_bit(In_sync, &rdev->flags)) {
1617                unsigned long flags;
1618                spin_lock_irqsave(&conf->device_lock, flags);
1619                mddev->degraded++;
1620                spin_unlock_irqrestore(&conf->device_lock, flags);
1621                /*
1622                 * if recovery is running, make sure it aborts.
1623                 */
1624                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1625        }
1626        set_bit(Blocked, &rdev->flags);
1627        set_bit(Faulty, &rdev->flags);
1628        set_bit(MD_CHANGE_DEVS, &mddev->flags);
1629        printk(KERN_ALERT
1630               "md/raid10:%s: Disk failure on %s, disabling device.\n"
1631               "md/raid10:%s: Operation continuing on %d devices.\n",
1632               mdname(mddev), bdevname(rdev->bdev, b),
1633               mdname(mddev), conf->geo.raid_disks - mddev->degraded);
1634}
1635
1636static void print_conf(struct r10conf *conf)
1637{
1638        int i;
1639        struct raid10_info *tmp;
1640
1641        printk(KERN_DEBUG "RAID10 conf printout:\n");
1642        if (!conf) {
1643                printk(KERN_DEBUG "(!conf)\n");
1644                return;
1645        }
1646        printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->geo.raid_disks - conf->mddev->degraded,
1647                conf->geo.raid_disks);
1648
1649        for (i = 0; i < conf->geo.raid_disks; i++) {
1650                char b[BDEVNAME_SIZE];
1651                tmp = conf->mirrors + i;
1652                if (tmp->rdev)
1653                        printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1654                                i, !test_bit(In_sync, &tmp->rdev->flags),
1655                                !test_bit(Faulty, &tmp->rdev->flags),
1656                                bdevname(tmp->rdev->bdev,b));
1657        }
1658}
1659
1660static void close_sync(struct r10conf *conf)
1661{
1662        wait_barrier(conf);
1663        allow_barrier(conf);
1664
1665        mempool_destroy(conf->r10buf_pool);
1666        conf->r10buf_pool = NULL;
1667}
1668
1669static int raid10_spare_active(struct mddev *mddev)
1670{
1671        int i;
1672        struct r10conf *conf = mddev->private;
1673        struct raid10_info *tmp;
1674        int count = 0;
1675        unsigned long flags;
1676
1677        /*
1678         * Find all non-in_sync disks within the RAID10 configuration
1679         * and mark them in_sync
1680         */
1681        for (i = 0; i < conf->geo.raid_disks; i++) {
1682                tmp = conf->mirrors + i;
1683                if (tmp->replacement
1684                    && tmp->replacement->recovery_offset == MaxSector
1685                    && !test_bit(Faulty, &tmp->replacement->flags)
1686                    && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
1687                        /* Replacement has just become active */
1688                        if (!tmp->rdev
1689                            || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
1690                                count++;
1691                        if (tmp->rdev) {
1692                                /* Replaced device not technically faulty,
1693                                 * but we need to be sure it gets removed
1694                                 * and never re-added.
1695                                 */
1696                                set_bit(Faulty, &tmp->rdev->flags);
1697                                sysfs_notify_dirent_safe(
1698                                        tmp->rdev->sysfs_state);
1699                        }
1700                        sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
1701                } else if (tmp->rdev
1702                           && !test_bit(Faulty, &tmp->rdev->flags)
1703                           && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1704                        count++;
1705                        sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
1706                }
1707        }
1708        spin_lock_irqsave(&conf->device_lock, flags);
1709        mddev->degraded -= count;
1710        spin_unlock_irqrestore(&conf->device_lock, flags);
1711
1712        print_conf(conf);
1713        return count;
1714}
1715
1716
1717static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
1718{
1719        struct r10conf *conf = mddev->private;
1720        int err = -EEXIST;
1721        int mirror;
1722        int first = 0;
1723        int last = conf->geo.raid_disks - 1;
1724        struct request_queue *q = bdev_get_queue(rdev->bdev);
1725
1726        if (mddev->recovery_cp < MaxSector)
1727                /* only hot-add to in-sync arrays, as recovery is
1728                 * very different from resync
1729                 */
1730                return -EBUSY;
1731        if (rdev->saved_raid_disk < 0 && !_enough(conf, &conf->prev, -1))
1732                return -EINVAL;
1733
1734        if (rdev->raid_disk >= 0)
1735                first = last = rdev->raid_disk;
1736
1737        if (q->merge_bvec_fn) {
1738                set_bit(Unmerged, &rdev->flags);
1739                mddev->merge_check_needed = 1;
1740        }
1741
1742        if (rdev->saved_raid_disk >= first &&
1743            conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1744                mirror = rdev->saved_raid_disk;
1745        else
1746                mirror = first;
1747        for ( ; mirror <= last ; mirror++) {
1748                struct raid10_info *p = &conf->mirrors[mirror];
1749                if (p->recovery_disabled == mddev->recovery_disabled)
1750                        continue;
1751                if (p->rdev) {
1752                        if (!test_bit(WantReplacement, &p->rdev->flags) ||
1753                            p->replacement != NULL)
1754                                continue;
1755                        clear_bit(In_sync, &rdev->flags);
1756                        set_bit(Replacement, &rdev->flags);
1757                        rdev->raid_disk = mirror;
1758                        err = 0;
1759                        disk_stack_limits(mddev->gendisk, rdev->bdev,
1760                                          rdev->data_offset << 9);
1761                        conf->fullsync = 1;
1762                        rcu_assign_pointer(p->replacement, rdev);
1763                        break;
1764                }
1765
1766                disk_stack_limits(mddev->gendisk, rdev->bdev,
1767                                  rdev->data_offset << 9);
1768
1769                p->head_position = 0;
1770                p->recovery_disabled = mddev->recovery_disabled - 1;
1771                rdev->raid_disk = mirror;
1772                err = 0;
1773                if (rdev->saved_raid_disk != mirror)
1774                        conf->fullsync = 1;
1775                rcu_assign_pointer(p->rdev, rdev);
1776                break;
1777        }
1778        if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
1779                /* Some requests might not have seen this new
1780                 * merge_bvec_fn.  We must wait for them to complete
1781                 * before merging the device fully.
1782                 * First we make sure any code which has tested
1783                 * our function has submitted the request, then
1784                 * we wait for all outstanding requests to complete.
1785                 */
1786                synchronize_sched();
1787                raise_barrier(conf, 0);
1788                lower_barrier(conf);
1789                clear_bit(Unmerged, &rdev->flags);
1790        }
1791        md_integrity_add_rdev(rdev, mddev);
1792        if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
1793                queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
1794
1795        print_conf(conf);
1796        return err;
1797}
1798
1799static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
1800{
1801        struct r10conf *conf = mddev->private;
1802        int err = 0;
1803        int number = rdev->raid_disk;
1804        struct md_rdev **rdevp;
1805        struct raid10_info *p = conf->mirrors + number;
1806
1807        print_conf(conf);
1808        if (rdev == p->rdev)
1809                rdevp = &p->rdev;
1810        else if (rdev == p->replacement)
1811                rdevp = &p->replacement;
1812        else
1813                return 0;
1814
1815        if (test_bit(In_sync, &rdev->flags) ||
1816            atomic_read(&rdev->nr_pending)) {
1817                err = -EBUSY;
1818                goto abort;
1819        }
1820        /* Only remove faulty devices if recovery
1821         * is not possible.
1822         */
1823        if (!test_bit(Faulty, &rdev->flags) &&
1824            mddev->recovery_disabled != p->recovery_disabled &&
1825            (!p->replacement || p->replacement == rdev) &&
1826            number < conf->geo.raid_disks &&
1827            enough(conf, -1)) {
1828                err = -EBUSY;
1829                goto abort;
1830        }
1831        *rdevp = NULL;
1832        synchronize_rcu();
1833        if (atomic_read(&rdev->nr_pending)) {
1834                /* lost the race, try later */
1835                err = -EBUSY;
1836                *rdevp = rdev;
1837                goto abort;
1838        } else if (p->replacement) {
1839                /* We must have just cleared 'rdev' */
1840                p->rdev = p->replacement;
1841                clear_bit(Replacement, &p->replacement->flags);
1842                smp_mb(); /* Make sure other CPUs may see both as identical
1843                           * but will never see neither -- if they are careful.
1844                           */
1845                p->replacement = NULL;
1846                clear_bit(WantReplacement, &rdev->flags);
1847        } else
1848                /* We might have just remove the Replacement as faulty
1849                 * Clear the flag just in case
1850                 */
1851                clear_bit(WantReplacement, &rdev->flags);
1852
1853        err = md_integrity_register(mddev);
1854
1855abort:
1856
1857        print_conf(conf);
1858        return err;
1859}
1860
1861
1862static void end_sync_read(struct bio *bio, int error)
1863{
1864        struct r10bio *r10_bio = bio->bi_private;
1865        struct r10conf *conf = r10_bio->mddev->private;
1866        int d;
1867
1868        if (bio == r10_bio->master_bio) {
1869                /* this is a reshape read */
1870                d = r10_bio->read_slot; /* really the read dev */
1871        } else
1872                d = find_bio_disk(conf, r10_bio, bio, NULL, NULL);
1873
1874        if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1875                set_bit(R10BIO_Uptodate, &r10_bio->state);
1876        else
1877                /* The write handler will notice the lack of
1878                 * R10BIO_Uptodate and record any errors etc
1879                 */
1880                atomic_add(r10_bio->sectors,
1881                           &conf->mirrors[d].rdev->corrected_errors);
1882
1883        /* for reconstruct, we always reschedule after a read.
1884         * for resync, only after all reads
1885         */
1886        rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1887        if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1888            atomic_dec_and_test(&r10_bio->remaining)) {
1889                /* we have read all the blocks,
1890                 * do the comparison in process context in raid10d
1891                 */
1892                reschedule_retry(r10_bio);
1893        }
1894}
1895
1896static void end_sync_request(struct r10bio *r10_bio)
1897{
1898        struct mddev *mddev = r10_bio->mddev;
1899
1900        while (atomic_dec_and_test(&r10_bio->remaining)) {
1901                if (r10_bio->master_bio == NULL) {
1902                        /* the primary of several recovery bios */
1903                        sector_t s = r10_bio->sectors;
1904                        if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1905                            test_bit(R10BIO_WriteError, &r10_bio->state))
1906                                reschedule_retry(r10_bio);
1907                        else
1908                                put_buf(r10_bio);
1909                        md_done_sync(mddev, s, 1);
1910                        break;
1911                } else {
1912                        struct r10bio *r10_bio2 = (struct r10bio *)r10_bio->master_bio;
1913                        if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
1914                            test_bit(R10BIO_WriteError, &r10_bio->state))
1915                                reschedule_retry(r10_bio);
1916                        else
1917                                put_buf(r10_bio);
1918                        r10_bio = r10_bio2;
1919                }
1920        }
1921}
1922
1923static void end_sync_write(struct bio *bio, int error)
1924{
1925        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1926        struct r10bio *r10_bio = bio->bi_private;
1927        struct mddev *mddev = r10_bio->mddev;
1928        struct r10conf *conf = mddev->private;
1929        int d;
1930        sector_t first_bad;
1931        int bad_sectors;
1932        int slot;
1933        int repl;
1934        struct md_rdev *rdev = NULL;
1935
1936        d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
1937        if (repl)
1938                rdev = conf->mirrors[d].replacement;
1939        else
1940                rdev = conf->mirrors[d].rdev;
1941
1942        if (!uptodate) {
1943                if (repl)
1944                        md_error(mddev, rdev);
1945                else {
1946                        set_bit(WriteErrorSeen, &rdev->flags);
1947                        if (!test_and_set_bit(WantReplacement, &rdev->flags))
1948                                set_bit(MD_RECOVERY_NEEDED,
1949                                        &rdev->mddev->recovery);
1950                        set_bit(R10BIO_WriteError, &r10_bio->state);
1951                }
1952        } else if (is_badblock(rdev,
1953                             r10_bio->devs[slot].addr,
1954                             r10_bio->sectors,
1955                             &first_bad, &bad_sectors))
1956                set_bit(R10BIO_MadeGood, &r10_bio->state);
1957
1958        rdev_dec_pending(rdev, mddev);
1959
1960        end_sync_request(r10_bio);
1961}
1962
1963/*
1964 * Note: sync and recover and handled very differently for raid10
1965 * This code is for resync.
1966 * For resync, we read through virtual addresses and read all blocks.
1967 * If there is any error, we schedule a write.  The lowest numbered
1968 * drive is authoritative.
1969 * However requests come for physical address, so we need to map.
1970 * For every physical address there are raid_disks/copies virtual addresses,
1971 * which is always are least one, but is not necessarly an integer.
1972 * This means that a physical address can span multiple chunks, so we may
1973 * have to submit multiple io requests for a single sync request.
1974 */
1975/*
1976 * We check if all blocks are in-sync and only write to blocks that
1977 * aren't in sync
1978 */
1979static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
1980{
1981        struct r10conf *conf = mddev->private;
1982        int i, first;
1983        struct bio *tbio, *fbio;
1984        int vcnt;
1985
1986        atomic_set(&r10_bio->remaining, 1);
1987
1988        /* find the first device with a block */
1989        for (i=0; i<conf->copies; i++)
1990                if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
1991                        break;
1992
1993        if (i == conf->copies)
1994                goto done;
1995
1996        first = i;
1997        fbio = r10_bio->devs[i].bio;
1998
1999        vcnt = (r10_bio->sectors + (PAGE_SIZE >> 9) - 1) >> (PAGE_SHIFT - 9);
2000        /* now find blocks with errors */
2001        for (i=0 ; i < conf->copies ; i++) {
2002                int  j, d;
2003
2004                tbio = r10_bio->devs[i].bio;
2005
2006                if (tbio->bi_end_io != end_sync_read)
2007                        continue;
2008                if (i == first)
2009                        continue;
2010                if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
2011                        /* We know that the bi_io_vec layout is the same for
2012                         * both 'first' and 'i', so we just compare them.
2013                         * All vec entries are PAGE_SIZE;
2014                         */
2015                        for (j = 0; j < vcnt; j++)
2016                                if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
2017                                           page_address(tbio->bi_io_vec[j].bv_page),
2018                                           fbio->bi_io_vec[j].bv_len))
2019                                        break;
2020                        if (j == vcnt)
2021                                continue;
2022                        atomic64_add(r10_bio->sectors, &mddev->resync_mismatches);
2023                        if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
2024                                /* Don't fix anything. */
2025                                continue;
2026                }
2027                /* Ok, we need to write this bio, either to correct an
2028                 * inconsistency or to correct an unreadable block.
2029                 * First we need to fixup bv_offset, bv_len and
2030                 * bi_vecs, as the read request might have corrupted these
2031                 */
2032                tbio->bi_vcnt = vcnt;
2033                tbio->bi_size = r10_bio->sectors << 9;
2034                tbio->bi_idx = 0;
2035                tbio->bi_phys_segments = 0;
2036                tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
2037                tbio->bi_flags |= 1 << BIO_UPTODATE;
2038                tbio->bi_next = NULL;
2039                tbio->bi_rw = WRITE;
2040                tbio->bi_private = r10_bio;
2041                tbio->bi_sector = r10_bio->devs[i].addr;
2042
2043                for (j=0; j < vcnt ; j++) {
2044                        tbio->bi_io_vec[j].bv_offset = 0;
2045                        tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
2046
2047                        memcpy(page_address(tbio->bi_io_vec[j].bv_page),
2048                               page_address(fbio->bi_io_vec[j].bv_page),
2049                               PAGE_SIZE);
2050                }
2051                tbio->bi_end_io = end_sync_write;
2052
2053                d = r10_bio->devs[i].devnum;
2054                atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2055                atomic_inc(&r10_bio->remaining);
2056                md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
2057
2058                tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
2059                tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
2060                generic_make_request(tbio);
2061        }
2062
2063        /* Now write out to any replacement devices
2064         * that are active
2065         */
2066        for (i = 0; i < conf->copies; i++) {
2067                int j, d;
2068
2069                tbio = r10_bio->devs[i].repl_bio;
2070                if (!tbio || !tbio->bi_end_io)
2071                        continue;
2072                if (r10_bio->devs[i].bio->bi_end_io != end_sync_write
2073                    && r10_bio->devs[i].bio != fbio)
2074                        for (j = 0; j < vcnt; j++)
2075                                memcpy(page_address(tbio->bi_io_vec[j].bv_page),
2076                                       page_address(fbio->bi_io_vec[j].bv_page),
2077                                       PAGE_SIZE);
2078                d = r10_bio->devs[i].devnum;
2079                atomic_inc(&r10_bio->remaining);
2080                md_sync_acct(conf->mirrors[d].replacement->bdev,
2081                             tbio->bi_size >> 9);
2082                generic_make_request(tbio);
2083        }
2084
2085done:
2086        if (atomic_dec_and_test(&r10_bio->remaining)) {
2087                md_done_sync(mddev, r10_bio->sectors, 1);
2088                put_buf(r10_bio);
2089        }
2090}
2091
2092/*
2093 * Now for the recovery code.
2094 * Recovery happens across physical sectors.
2095 * We recover all non-is_sync drives by finding the virtual address of
2096 * each, and then choose a working drive that also has that virt address.
2097 * There is a separate r10_bio for each non-in_sync drive.
2098 * Only the first two slots are in use. The first for reading,
2099 * The second for writing.
2100 *
2101 */
2102static void fix_recovery_read_error(struct r10bio *r10_bio)
2103{
2104        /* We got a read error during recovery.
2105         * We repeat the read in smaller page-sized sections.
2106         * If a read succeeds, write it to the new device or record
2107         * a bad block if we cannot.
2108         * If a read fails, record a bad block on both old and
2109         * new devices.
2110         */
2111        struct mddev *mddev = r10_bio->mddev;
2112        struct r10conf *conf = mddev->private;
2113        struct bio *bio = r10_bio->devs[0].bio;
2114        sector_t sect = 0;
2115        int sectors = r10_bio->sectors;
2116        int idx = 0;
2117        int dr = r10_bio->devs[0].devnum;
2118        int dw = r10_bio->devs[1].devnum;
2119
2120        while (sectors) {
2121                int s = sectors;
2122                struct md_rdev *rdev;
2123                sector_t addr;
2124                int ok;
2125
2126                if (s > (PAGE_SIZE>>9))
2127                        s = PAGE_SIZE >> 9;
2128
2129                rdev = conf->mirrors[dr].rdev;
2130                addr = r10_bio->devs[0].addr + sect,
2131                ok = sync_page_io(rdev,
2132                                  addr,
2133                                  s << 9,
2134                                  bio->bi_io_vec[idx].bv_page,
2135                                  READ, false);
2136                if (ok) {
2137                        rdev = conf->mirrors[dw].rdev;
2138                        addr = r10_bio->devs[1].addr + sect;
2139                        ok = sync_page_io(rdev,
2140                                          addr,
2141                                          s << 9,
2142                                          bio->bi_io_vec[idx].bv_page,
2143                                          WRITE, false);
2144                        if (!ok) {
2145                                set_bit(WriteErrorSeen, &rdev->flags);
2146                                if (!test_and_set_bit(WantReplacement,
2147                                                      &rdev->flags))
2148                                        set_bit(MD_RECOVERY_NEEDED,
2149                                                &rdev->mddev->recovery);
2150                        }
2151                }
2152                if (!ok) {
2153                        /* We don't worry if we cannot set a bad block -
2154                         * it really is bad so there is no loss in not
2155                         * recording it yet
2156                         */
2157                        rdev_set_badblocks(rdev, addr, s, 0);
2158
2159                        if (rdev != conf->mirrors[dw].rdev) {
2160                                /* need bad block on destination too */
2161                                struct md_rdev *rdev2 = conf->mirrors[dw].rdev;
2162                                addr = r10_bio->devs[1].addr + sect;
2163                                ok = rdev_set_badblocks(rdev2, addr, s, 0);
2164                                if (!ok) {
2165                                        /* just abort the recovery */
2166                                        printk(KERN_NOTICE
2167                                               "md/raid10:%s: recovery aborted"
2168                                               " due to read error\n",
2169                                               mdname(mddev));
2170
2171                                        conf->mirrors[dw].recovery_disabled
2172                                                = mddev->recovery_disabled;
2173                                        set_bit(MD_RECOVERY_INTR,
2174                                                &mddev->recovery);
2175                                        break;
2176                                }
2177                        }
2178                }
2179
2180                sectors -= s;
2181                sect += s;
2182                idx++;
2183        }
2184}
2185
2186static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio)
2187{
2188        struct r10conf *conf = mddev->private;
2189        int d;
2190        struct bio *wbio, *wbio2;
2191
2192        if (!test_bit(R10BIO_Uptodate, &r10_bio->state)) {
2193                fix_recovery_read_error(r10_bio);
2194                end_sync_request(r10_bio);
2195                return;
2196        }
2197
2198        /*
2199         * share the pages with the first bio
2200         * and submit the write request
2201         */
2202        d = r10_bio->devs[1].devnum;
2203        wbio = r10_bio->devs[1].bio;
2204        wbio2 = r10_bio->devs[1].repl_bio;
2205        if (wbio->bi_end_io) {
2206                atomic_inc(&conf->mirrors[d].rdev->nr_pending);
2207                md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
2208                generic_make_request(wbio);
2209        }
2210        if (wbio2 && wbio2->bi_end_io) {
2211                atomic_inc(&conf->mirrors[d].replacement->nr_pending);
2212                md_sync_acct(conf->mirrors[d].replacement->bdev,
2213                             wbio2->bi_size >> 9);
2214                generic_make_request(wbio2);
2215        }
2216}
2217
2218
2219/*
2220 * Used by fix_read_error() to decay the per rdev read_errors.
2221 * We halve the read error count for every hour that has elapsed
2222 * since the last recorded read error.
2223 *
2224 */
2225static void check_decay_read_errors(struct mddev *mddev, struct md_rdev *rdev)
2226{
2227        struct timespec cur_time_mon;
2228        unsigned long hours_since_last;
2229        unsigned int read_errors = atomic_read(&rdev->read_errors);
2230
2231        ktime_get_ts(&cur_time_mon);
2232
2233        if (rdev->last_read_error.tv_sec == 0 &&
2234            rdev->last_read_error.tv_nsec == 0) {
2235                /* first time we've seen a read error */
2236                rdev->last_read_error = cur_time_mon;
2237                return;
2238        }
2239
2240        hours_since_last = (cur_time_mon.tv_sec -
2241                            rdev->last_read_error.tv_sec) / 3600;
2242
2243        rdev->last_read_error = cur_time_mon;
2244
2245        /*
2246         * if hours_since_last is > the number of bits in read_errors
2247         * just set read errors to 0. We do this to avoid
2248         * overflowing the shift of read_errors by hours_since_last.
2249         */
2250        if (hours_since_last >= 8 * sizeof(read_errors))
2251                atomic_set(&rdev->read_errors, 0);
2252        else
2253                atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
2254}
2255
2256static int r10_sync_page_io(struct md_rdev *rdev, sector_t sector,
2257                            int sectors, struct page *page, int rw)
2258{
2259        sector_t first_bad;
2260        int bad_sectors;
2261
2262        if (is_badblock(rdev, sector, sectors, &first_bad, &bad_sectors)
2263            && (rw == READ || test_bit(WriteErrorSeen, &rdev->flags)))
2264                return -1;
2265        if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
2266                /* success */
2267                return 1;
2268        if (rw == WRITE) {
2269                set_bit(WriteErrorSeen, &rdev->flags);
2270                if (!test_and_set_bit(WantReplacement, &rdev->flags))
2271                        set_bit(MD_RECOVERY_NEEDED,
2272                                &rdev->mddev->recovery);
2273        }
2274        /* need to record an error - either for the block or the device */
2275        if (!rdev_set_badblocks(rdev, sector, sectors, 0))
2276                md_error(rdev->mddev, rdev);
2277        return 0;
2278}
2279
2280/*
2281 * This is a kernel thread which:
2282 *
2283 *      1.      Retries failed read operations on working mirrors.
2284 *      2.      Updates the raid superblock when problems encounter.
2285 *      3.      Performs writes following reads for array synchronising.
2286 */
2287
2288static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10bio *r10_bio)
2289{
2290        int sect = 0; /* Offset from r10_bio->sector */
2291        int sectors = r10_bio->sectors;
2292        struct md_rdev*rdev;
2293        int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
2294        int d = r10_bio->devs[r10_bio->read_slot].devnum;
2295
2296        /* still own a reference to this rdev, so it cannot
2297         * have been cleared recently.
2298         */
2299        rdev = conf->mirrors[d].rdev;
2300
2301        if (test_bit(Faulty, &rdev->flags))
2302                /* drive has already been failed, just ignore any
2303                   more fix_read_error() attempts */
2304                return;
2305
2306        check_decay_read_errors(mddev, rdev);
2307        atomic_inc(&rdev->read_errors);
2308        if (atomic_read(&rdev->read_errors) > max_read_errors) {
2309                char b[BDEVNAME_SIZE];
2310                bdevname(rdev->bdev, b);
2311
2312                printk(KERN_NOTICE
2313                       "md/raid10:%s: %s: Raid device exceeded "
2314                       "read_error threshold [cur %d:max %d]\n",
2315                       mdname(mddev), b,
2316                       atomic_read(&rdev->read_errors), max_read_errors);
2317                printk(KERN_NOTICE
2318                       "md/raid10:%s: %s: Failing raid device\n",
2319                       mdname(mddev), b);
2320                md_error(mddev, conf->mirrors[d].rdev);
2321                r10_bio->devs[r10_bio->read_slot].bio = IO_BLOCKED;
2322                return;
2323        }
2324
2325        while(sectors) {
2326                int s = sectors;
2327                int sl = r10_bio->read_slot;
2328                int success = 0;
2329                int start;
2330
2331                if (s > (PAGE_SIZE>>9))
2332                        s = PAGE_SIZE >> 9;
2333
2334                rcu_read_lock();
2335                do {
2336                        sector_t first_bad;
2337                        int bad_sectors;
2338
2339                        d = r10_bio->devs[sl].devnum;
2340                        rdev = rcu_dereference(conf->mirrors[d].rdev);
2341                        if (rdev &&
2342                            !test_bit(Unmerged, &rdev->flags) &&
2343                            test_bit(In_sync, &rdev->flags) &&
2344                            is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
2345                                        &first_bad, &bad_sectors) == 0) {
2346                                atomic_inc(&rdev->nr_pending);
2347                                rcu_read_unlock();
2348                                success = sync_page_io(rdev,
2349                                                       r10_bio->devs[sl].addr +
2350                                                       sect,
2351                                                       s<<9,
2352                                                       conf->tmppage, READ, false);
2353                                rdev_dec_pending(rdev, mddev);
2354                                rcu_read_lock();
2355                                if (success)
2356                                        break;
2357                        }
2358                        sl++;
2359                        if (sl == conf->copies)
2360                                sl = 0;
2361                } while (!success && sl != r10_bio->read_slot);
2362                rcu_read_unlock();
2363
2364                if (!success) {
2365                        /* Cannot read from anywhere, just mark the block
2366                         * as bad on the first device to discourage future
2367                         * reads.
2368                         */
2369                        int dn = r10_bio->devs[r10_bio->read_slot].devnum;
2370                        rdev = conf->mirrors[dn].rdev;
2371
2372                        if (!rdev_set_badblocks(
2373                                    rdev,
2374                                    r10_bio->devs[r10_bio->read_slot].addr
2375                                    + sect,
2376                                    s, 0)) {
2377                                md_error(mddev, rdev);
2378                                r10_bio->devs[r10_bio->read_slot].bio
2379                                        = IO_BLOCKED;
2380                        }
2381                        break;
2382                }
2383
2384                start = sl;
2385                /* write it back and re-read */
2386                rcu_read_lock();
2387                while (sl != r10_bio->read_slot) {
2388                        char b[BDEVNAME_SIZE];
2389
2390                        if (sl==0)
2391                                sl = conf->copies;
2392                        sl--;
2393                        d = r10_bio->devs[sl].devnum;
2394                        rdev = rcu_dereference(conf->mirrors[d].rdev);
2395                        if (!rdev ||
2396                            test_bit(Unmerged, &rdev->flags) ||
2397                            !test_bit(In_sync, &rdev->flags))
2398                                continue;
2399
2400                        atomic_inc(&rdev->nr_pending);
2401                        rcu_read_unlock();
2402                        if (r10_sync_page_io(rdev,
2403                                             r10_bio->devs[sl].addr +
2404                                             sect,
2405                                             s, conf->tmppage, WRITE)
2406                            == 0) {
2407                                /* Well, this device is dead */
2408                                printk(KERN_NOTICE
2409                                       "md/raid10:%s: read correction "
2410                                       "write failed"
2411                                       " (%d sectors at %llu on %s)\n",
2412                                       mdname(mddev), s,
2413                                       (unsigned long long)(
2414                                               sect +
2415                                               choose_data_offset(r10_bio,
2416                                                                  rdev)),
2417                                       bdevname(rdev->bdev, b));
2418                                printk(KERN_NOTICE "md/raid10:%s: %s: failing "
2419                                       "drive\n",
2420                                       mdname(mddev),
2421                                       bdevname(rdev->bdev, b));
2422                        }
2423                        rdev_dec_pending(rdev, mddev);
2424                        rcu_read_lock();
2425                }
2426                sl = start;
2427                while (sl != r10_bio->read_slot) {
2428                        char b[BDEVNAME_SIZE];
2429
2430                        if (sl==0)
2431                                sl = conf->copies;
2432                        sl--;
2433                        d = r10_bio->devs[sl].devnum;
2434                        rdev = rcu_dereference(conf->mirrors[d].rdev);
2435                        if (!rdev ||
2436                            !test_bit(In_sync, &rdev->flags))
2437                                continue;
2438
2439                        atomic_inc(&rdev->nr_pending);
2440                        rcu_read_unlock();
2441                        switch (r10_sync_page_io(rdev,
2442                                             r10_bio->devs[sl].addr +
2443                                             sect,
2444                                             s, conf->tmppage,
2445                                                 READ)) {
2446                        case 0:
2447                                /* Well, this device is dead */
2448                                printk(KERN_NOTICE
2449                                       "md/raid10:%s: unable to read back "
2450                                       "corrected sectors"
2451                                       " (%d sectors at %llu on %s)\n",
2452                                       mdname(mddev), s,
2453                                       (unsigned long long)(
2454                                               sect +
2455                                               choose_data_offset(r10_bio, rdev)),
2456                                       bdevname(rdev->bdev, b));
2457                                printk(KERN_NOTICE "md/raid10:%s: %s: failing "
2458                                       "drive\n",
2459                                       mdname(mddev),
2460                                       bdevname(rdev->bdev, b));
2461                                break;
2462                        case 1:
2463                                printk(KERN_INFO
2464                                       "md/raid10:%s: read error corrected"
2465                                       " (%d sectors at %llu on %s)\n",
2466                                       mdname(mddev), s,
2467                                       (unsigned long long)(
2468                                               sect +
2469                                               choose_data_offset(r10_bio, rdev)),
2470                                       bdevname(rdev->bdev, b));
2471                                atomic_add(s, &rdev->corrected_errors);
2472                        }
2473
2474                        rdev_dec_pending(rdev, mddev);
2475                        rcu_read_lock();
2476                }
2477                rcu_read_unlock();
2478
2479                sectors -= s;
2480                sect += s;
2481        }
2482}
2483
2484static void bi_complete(struct bio *bio, int error)
2485{
2486        complete((struct completion *)bio->bi_private);
2487}
2488
2489static int submit_bio_wait(int rw, struct bio *bio)
2490{
2491        struct completion event;
2492        rw |= REQ_SYNC;
2493
2494        init_completion(&event);
2495        bio->bi_private = &event;
2496        bio->bi_end_io = bi_complete;
2497        submit_bio(rw, bio);
2498        wait_for_completion(&event);
2499
2500        return test_bit(BIO_UPTODATE, &bio->bi_flags);
2501}
2502
2503static int narrow_write_error(struct r10bio *r10_bio, int i)
2504{
2505        struct bio *bio = r10_bio->master_bio;
2506        struct mddev *mddev = r10_bio->mddev;
2507        struct r10conf *conf = mddev->private;
2508        struct md_rdev *rdev = conf->mirrors[r10_bio->devs[i].devnum].rdev;
2509        /* bio has the data to be written to slot 'i' where
2510         * we just recently had a write error.
2511         * We repeatedly clone the bio and trim down to one block,
2512         * then try the write.  Where the write fails we record
2513         * a bad block.
2514         * It is conceivable that the bio doesn't exactly align with
2515         * blocks.  We must handle this.
2516         *
2517         * We currently own a reference to the rdev.
2518         */
2519
2520        int block_sectors;
2521        sector_t sector;
2522        int sectors;
2523        int sect_to_write = r10_bio->sectors;
2524        int ok = 1;
2525
2526        if (rdev->badblocks.shift < 0)
2527                return 0;
2528
2529        block_sectors = 1 << rdev->badblocks.shift;
2530        sector = r10_bio->sector;
2531        sectors = ((r10_bio->sector + block_sectors)
2532                   & ~(sector_t)(block_sectors - 1))
2533                - sector;
2534
2535        while (sect_to_write) {
2536                struct bio *wbio;
2537                if (sectors > sect_to_write)
2538                        sectors = sect_to_write;
2539                /* Write at 'sector' for 'sectors' */
2540                wbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
2541                md_trim_bio(wbio, sector - bio->bi_sector, sectors);
2542                wbio->bi_sector = (r10_bio->devs[i].addr+
2543                                   choose_data_offset(r10_bio, rdev) +
2544                                   (sector - r10_bio->sector));
2545                wbio->bi_bdev = rdev->bdev;
2546                if (submit_bio_wait(WRITE, wbio) == 0)
2547                        /* Failure! */
2548                        ok = rdev_set_badblocks(rdev, sector,
2549                                                sectors, 0)
2550                                && ok;
2551
2552                bio_put(wbio);
2553                sect_to_write -= sectors;
2554                sector += sectors;
2555                sectors = block_sectors;
2556        }
2557        return ok;
2558}
2559
2560static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
2561{
2562        int slot = r10_bio->read_slot;
2563        struct bio *bio;
2564        struct r10conf *conf = mddev->private;
2565        struct md_rdev *rdev = r10_bio->devs[slot].rdev;
2566        char b[BDEVNAME_SIZE];
2567        unsigned long do_sync;
2568        int max_sectors;
2569
2570        /* we got a read error. Maybe the drive is bad.  Maybe just
2571         * the block and we can fix it.
2572         * We freeze all other IO, and try reading the block from
2573         * other devices.  When we find one, we re-write
2574         * and check it that fixes the read error.
2575         * This is all done synchronously while the array is
2576         * frozen.
2577         */
2578        bio = r10_bio->devs[slot].bio;
2579        bdevname(bio->bi_bdev, b);
2580        bio_put(bio);
2581        r10_bio->devs[slot].bio = NULL;
2582
2583        if (mddev->ro == 0) {
2584                freeze_array(conf);
2585                fix_read_error(conf, mddev, r10_bio);
2586                unfreeze_array(conf);
2587        } else
2588                r10_bio->devs[slot].bio = IO_BLOCKED;
2589
2590        rdev_dec_pending(rdev, mddev);
2591
2592read_more:
2593        rdev = read_balance(conf, r10_bio, &max_sectors);
2594        if (rdev == NULL) {
2595                printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
2596                       " read error for block %llu\n",
2597                       mdname(mddev), b,
2598                       (unsigned long long)r10_bio->sector);
2599                raid_end_bio_io(r10_bio);
2600                return;
2601        }
2602
2603        do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
2604        slot = r10_bio->read_slot;
2605        printk_ratelimited(
2606                KERN_ERR
2607                "md/raid10:%s: %s: redirecting "
2608                "sector %llu to another mirror\n",
2609                mdname(mddev),
2610                bdevname(rdev->bdev, b),
2611                (unsigned long long)r10_bio->sector);
2612        bio = bio_clone_mddev(r10_bio->master_bio,
2613                              GFP_NOIO, mddev);
2614        md_trim_bio(bio,
2615                    r10_bio->sector - bio->bi_sector,
2616                    max_sectors);
2617        r10_bio->devs[slot].bio = bio;
2618        r10_bio->devs[slot].rdev = rdev;
2619        bio->bi_sector = r10_bio->devs[slot].addr
2620                + choose_data_offset(r10_bio, rdev);
2621        bio->bi_bdev = rdev->bdev;
2622        bio->bi_rw = READ | do_sync;
2623        bio->bi_private = r10_bio;
2624        bio->bi_end_io = raid10_end_read_request;
2625        if (max_sectors < r10_bio->sectors) {
2626                /* Drat - have to split this up more */
2627                struct bio *mbio = r10_bio->master_bio;
2628                int sectors_handled =
2629                        r10_bio->sector + max_sectors
2630                        - mbio->bi_sector;
2631                r10_bio->sectors = max_sectors;
2632                spin_lock_irq(&conf->device_lock);
2633                if (mbio->bi_phys_segments == 0)
2634                        mbio->bi_phys_segments = 2;
2635                else
2636                        mbio->bi_phys_segments++;
2637                spin_unlock_irq(&conf->device_lock);
2638                generic_make_request(bio);
2639
2640                r10_bio = mempool_alloc(conf->r10bio_pool,
2641                                        GFP_NOIO);
2642                r10_bio->master_bio = mbio;
2643                r10_bio->sectors = (mbio->bi_size >> 9)
2644                        - sectors_handled;
2645                r10_bio->state = 0;
2646                set_bit(R10BIO_ReadError,
2647                        &r10_bio->state);
2648                r10_bio->mddev = mddev;
2649                r10_bio->sector = mbio->bi_sector
2650                        + sectors_handled;
2651
2652                goto read_more;
2653        } else
2654                generic_make_request(bio);
2655}
2656
2657static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
2658{
2659        /* Some sort of write request has finished and it
2660         * succeeded in writing where we thought there was a
2661         * bad block.  So forget the bad block.
2662         * Or possibly if failed and we need to record
2663         * a bad block.
2664         */
2665        int m;
2666        struct md_rdev *rdev;
2667
2668        if (test_bit(R10BIO_IsSync, &r10_bio->state) ||
2669            test_bit(R10BIO_IsRecover, &r10_bio->state)) {
2670                for (m = 0; m < conf->copies; m++) {
2671                        int dev = r10_bio->devs[m].devnum;
2672                        rdev = conf->mirrors[dev].rdev;
2673                        if (r10_bio->devs[m].bio == NULL)
2674                                continue;
2675                        if (test_bit(BIO_UPTODATE,
2676                                     &r10_bio->devs[m].bio->bi_flags)) {
2677                                rdev_clear_badblocks(
2678                                        rdev,
2679                                        r10_bio->devs[m].addr,
2680                                        r10_bio->sectors, 0);
2681                        } else {
2682                                if (!rdev_set_badblocks(
2683                                            rdev,
2684                                            r10_bio->devs[m].addr,
2685                                            r10_bio->sectors, 0))
2686                                        md_error(conf->mddev, rdev);
2687                        }
2688                        rdev = conf->mirrors[dev].replacement;
2689                        if (r10_bio->devs[m].repl_bio == NULL)
2690                                continue;
2691                        if (test_bit(BIO_UPTODATE,
2692                                     &r10_bio->devs[m].repl_bio->bi_flags)) {
2693                                rdev_clear_badblocks(
2694                                        rdev,
2695                                        r10_bio->devs[m].addr,
2696                                        r10_bio->sectors, 0);
2697                        } else {
2698                                if (!rdev_set_badblocks(
2699                                            rdev,
2700                                            r10_bio->devs[m].addr,
2701                                            r10_bio->sectors, 0))
2702                                        md_error(conf->mddev, rdev);
2703                        }
2704                }
2705                put_buf(r10_bio);
2706        } else {
2707                for (m = 0; m < conf->copies; m++) {
2708                        int dev = r10_bio->devs[m].devnum;
2709                        struct bio *bio = r10_bio->devs[m].bio;
2710                        rdev = conf->mirrors[dev].rdev;
2711                        if (bio == IO_MADE_GOOD) {
2712                                rdev_clear_badblocks(
2713                                        rdev,
2714                                        r10_bio->devs[m].addr,
2715                                        r10_bio->sectors, 0);
2716                                rdev_dec_pending(rdev, conf->mddev);
2717                        } else if (bio != NULL &&
2718                                   !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
2719                                if (!narrow_write_error(r10_bio, m)) {
2720                                        md_error(conf->mddev, rdev);
2721                                        set_bit(R10BIO_Degraded,
2722                                                &r10_bio->state);
2723                                }
2724                                rdev_dec_pending(rdev, conf->mddev);
2725                        }
2726                        bio = r10_bio->devs[m].repl_bio;
2727                        rdev = conf->mirrors[dev].replacement;
2728                        if (rdev && bio == IO_MADE_GOOD) {
2729                                rdev_clear_badblocks(
2730                                        rdev,
2731                                        r10_bio->devs[m].addr,
2732                                        r10_bio->sectors, 0);
2733                                rdev_dec_pending(rdev, conf->mddev);
2734                        }
2735                }
2736                if (test_bit(R10BIO_WriteError,
2737                             &r10_bio->state))
2738                        close_write(r10_bio);
2739                raid_end_bio_io(r10_bio);
2740        }
2741}
2742
2743static void raid10d(struct md_thread *thread)
2744{
2745        struct mddev *mddev = thread->mddev;
2746        struct r10bio *r10_bio;
2747        unsigned long flags;
2748        struct r10conf *conf = mddev->private;
2749        struct list_head *head = &conf->retry_list;
2750        struct blk_plug plug;
2751
2752        md_check_recovery(mddev);
2753
2754        blk_start_plug(&plug);
2755        for (;;) {
2756
2757                flush_pending_writes(conf);
2758
2759                spin_lock_irqsave(&conf->device_lock, flags);
2760                if (list_empty(head)) {
2761                        spin_unlock_irqrestore(&conf->device_lock, flags);
2762                        break;
2763                }
2764                r10_bio = list_entry(head->prev, struct r10bio, retry_list);
2765                list_del(head->prev);
2766                conf->nr_queued--;
2767                spin_unlock_irqrestore(&conf->device_lock, flags);
2768
2769                mddev = r10_bio->mddev;
2770                conf = mddev->private;
2771                if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
2772                    test_bit(R10BIO_WriteError, &r10_bio->state))
2773                        handle_write_completed(conf, r10_bio);
2774                else if (test_bit(R10BIO_IsReshape, &r10_bio->state))
2775                        reshape_request_write(mddev, r10_bio);
2776                else if (test_bit(R10BIO_IsSync, &r10_bio->state))
2777                        sync_request_write(mddev, r10_bio);
2778                else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
2779                        recovery_request_write(mddev, r10_bio);
2780                else if (test_bit(R10BIO_ReadError, &r10_bio->state))
2781                        handle_read_error(mddev, r10_bio);
2782                else {
2783                        /* just a partial read to be scheduled from a
2784                         * separate context
2785                         */
2786                        int slot = r10_bio->read_slot;
2787                        generic_make_request(r10_bio->devs[slot].bio);
2788                }
2789
2790                cond_resched();
2791                if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
2792                        md_check_recovery(mddev);
2793        }
2794        blk_finish_plug(&plug);
2795}
2796
2797
2798static int init_resync(struct r10conf *conf)
2799{
2800        int buffs;
2801        int i;
2802
2803        buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
2804        BUG_ON(conf->r10buf_pool);
2805        conf->have_replacement = 0;
2806        for (i = 0; i < conf->geo.raid_disks; i++)
2807                if (conf->mirrors[i].replacement)
2808                        conf->have_replacement = 1;
2809        conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
2810        if (!conf->r10buf_pool)
2811                return -ENOMEM;
2812        conf->next_resync = 0;
2813        return 0;
2814}
2815
2816/*
2817 * perform a "sync" on one "block"
2818 *
2819 * We need to make sure that no normal I/O request - particularly write
2820 * requests - conflict with active sync requests.
2821 *
2822 * This is achieved by tracking pending requests and a 'barrier' concept
2823 * that can be installed to exclude normal IO requests.
2824 *
2825 * Resync and recovery are handled very differently.
2826 * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
2827 *
2828 * For resync, we iterate over virtual addresses, read all copies,
2829 * and update if there are differences.  If only one copy is live,
2830 * skip it.
2831 * For recovery, we iterate over physical addresses, read a good
2832 * value for each non-in_sync drive, and over-write.
2833 *
2834 * So, for recovery we may have several outstanding complex requests for a
2835 * given address, one for each out-of-sync device.  We model this by allocating
2836 * a number of r10_bio structures, one for each out-of-sync device.
2837 * As we setup these structures, we collect all bio's together into a list
2838 * which we then process collectively to add pages, and then process again
2839 * to pass to generic_make_request.
2840 *
2841 * The r10_bio structures are linked using a borrowed master_bio pointer.
2842 * This link is counted in ->remaining.  When the r10_bio that points to NULL
2843 * has its remaining count decremented to 0, the whole complex operation
2844 * is complete.
2845 *
2846 */
2847
2848static sector_t sync_request(struct mddev *mddev, sector_t sector_nr,
2849                             int *skipped, int go_faster)
2850{
2851        struct r10conf *conf = mddev->private;
2852        struct r10bio *r10_bio;
2853        struct bio *biolist = NULL, *bio;
2854        sector_t max_sector, nr_sectors;
2855        int i;
2856        int max_sync;
2857        sector_t sync_blocks;
2858        sector_t sectors_skipped = 0;
2859        int chunks_skipped = 0;
2860        sector_t chunk_mask = conf->geo.chunk_mask;
2861
2862        if (!conf->r10buf_pool)
2863                if (init_resync(conf))
2864                        return 0;
2865
2866 skipped:
2867        max_sector = mddev->dev_sectors;
2868        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
2869            test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2870                max_sector = mddev->resync_max_sectors;
2871        if (sector_nr >= max_sector) {
2872                /* If we aborted, we need to abort the
2873                 * sync on the 'current' bitmap chucks (there can
2874                 * be several when recovering multiple devices).
2875                 * as we may have started syncing it but not finished.
2876                 * We can find the current address in
2877                 * mddev->curr_resync, but for recovery,
2878                 * we need to convert that to several
2879                 * virtual addresses.
2880                 */
2881                if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
2882                        end_reshape(conf);
2883                        return 0;
2884                }
2885
2886                if (mddev->curr_resync < max_sector) { /* aborted */
2887                        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
2888                                bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2889                                                &sync_blocks, 1);
2890                        else for (i = 0; i < conf->geo.raid_disks; i++) {
2891                                sector_t sect =
2892                                        raid10_find_virt(conf, mddev->curr_resync, i);
2893                                bitmap_end_sync(mddev->bitmap, sect,
2894                                                &sync_blocks, 1);
2895                        }
2896                } else {
2897                        /* completed sync */
2898                        if ((!mddev->bitmap || conf->fullsync)
2899                            && conf->have_replacement
2900                            && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
2901                                /* Completed a full sync so the replacements
2902                                 * are now fully recovered.
2903                                 */
2904                                for (i = 0; i < conf->geo.raid_disks; i++)
2905                                        if (conf->mirrors[i].replacement)
2906                                                conf->mirrors[i].replacement
2907                                                        ->recovery_offset
2908                                                        = MaxSector;
2909                        }
2910                        conf->fullsync = 0;
2911                }
2912                bitmap_close_sync(mddev->bitmap);
2913                close_sync(conf);
2914                *skipped = 1;
2915                return sectors_skipped;
2916        }
2917
2918        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2919                return reshape_request(mddev, sector_nr, skipped);
2920
2921        if (chunks_skipped >= conf->geo.raid_disks) {
2922                /* if there has been nothing to do on any drive,
2923                 * then there is nothing to do at all..
2924                 */
2925                *skipped = 1;
2926                return (max_sector - sector_nr) + sectors_skipped;
2927        }
2928
2929        if (max_sector > mddev->resync_max)
2930                max_sector = mddev->resync_max; /* Don't do IO beyond here */
2931
2932        /* make sure whole request will fit in a chunk - if chunks
2933         * are meaningful
2934         */
2935        if (conf->geo.near_copies < conf->geo.raid_disks &&
2936            max_sector > (sector_nr | chunk_mask))
2937                max_sector = (sector_nr | chunk_mask) + 1;
2938        /*
2939         * If there is non-resync activity waiting for us then
2940         * put in a delay to throttle resync.
2941         */
2942        if (!go_faster && conf->nr_waiting)
2943                msleep_interruptible(1000);
2944
2945        /* Again, very different code for resync and recovery.
2946         * Both must result in an r10bio with a list of bios that
2947         * have bi_end_io, bi_sector, bi_bdev set,
2948         * and bi_private set to the r10bio.
2949         * For recovery, we may actually create several r10bios
2950         * with 2 bios in each, that correspond to the bios in the main one.
2951         * In this case, the subordinate r10bios link back through a
2952         * borrowed master_bio pointer, and the counter in the master
2953         * includes a ref from each subordinate.
2954         */
2955        /* First, we decide what to do and set ->bi_end_io
2956         * To end_sync_read if we want to read, and
2957         * end_sync_write if we will want to write.
2958         */
2959
2960        max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
2961        if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
2962                /* recovery... the complicated one */
2963                int j;
2964                r10_bio = NULL;
2965
2966                for (i = 0 ; i < conf->geo.raid_disks; i++) {
2967                        int still_degraded;
2968                        struct r10bio *rb2;
2969                        sector_t sect;
2970                        int must_sync;
2971                        int any_working;
2972                        struct raid10_info *mirror = &conf->mirrors[i];
2973
2974                        if ((mirror->rdev == NULL ||
2975                             test_bit(In_sync, &mirror->rdev->flags))
2976                            &&
2977                            (mirror->replacement == NULL ||
2978                             test_bit(Faulty,
2979                                      &mirror->replacement->flags)))
2980                                continue;
2981
2982                        still_degraded = 0;
2983                        /* want to reconstruct this device */
2984                        rb2 = r10_bio;
2985                        sect = raid10_find_virt(conf, sector_nr, i);
2986                        if (sect >= mddev->resync_max_sectors) {
2987                                /* last stripe is not complete - don't
2988                                 * try to recover this sector.
2989                                 */
2990                                continue;
2991                        }
2992                        /* Unless we are doing a full sync, or a replacement
2993                         * we only need to recover the block if it is set in
2994                         * the bitmap
2995                         */
2996                        must_sync = bitmap_start_sync(mddev->bitmap, sect,
2997                                                      &sync_blocks, 1);
2998                        if (sync_blocks < max_sync)
2999                                max_sync = sync_blocks;
3000                        if (!must_sync &&
3001                            mirror->replacement == NULL &&
3002                            !conf->fullsync) {
3003                                /* yep, skip the sync_blocks here, but don't assume
3004                                 * that there will never be anything to do here
3005                                 */
3006                                chunks_skipped = -1;
3007                                continue;
3008                        }
3009
3010                        r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
3011                        raise_barrier(conf, rb2 != NULL);
3012                        atomic_set(&r10_bio->remaining, 0);
3013
3014                        r10_bio->master_bio = (struct bio*)rb2;
3015                        if (rb2)
3016                                atomic_inc(&rb2->remaining);
3017                        r10_bio->mddev = mddev;
3018                        set_bit(R10BIO_IsRecover, &r10_bio->state);
3019                        r10_bio->sector = sect;
3020
3021                        raid10_find_phys(conf, r10_bio);
3022
3023                        /* Need to check if the array will still be
3024                         * degraded
3025                         */
3026                        for (j = 0; j < conf->geo.raid_disks; j++)
3027                                if (conf->mirrors[j].rdev == NULL ||
3028                                    test_bit(Faulty, &conf->mirrors[j].rdev->flags)) {
3029                                        still_degraded = 1;
3030                                        break;
3031                                }
3032
3033                        must_sync = bitmap_start_sync(mddev->bitmap, sect,
3034                                                      &sync_blocks, still_degraded);
3035
3036                        any_working = 0;
3037                        for (j=0; j<conf->copies;j++) {
3038                                int k;
3039                                int d = r10_bio->devs[j].devnum;
3040                                sector_t from_addr, to_addr;
3041                                struct md_rdev *rdev;
3042                                sector_t sector, first_bad;
3043                                int bad_sectors;
3044                                if (!conf->mirrors[d].rdev ||
3045                                    !test_bit(In_sync, &conf->mirrors[d].rdev->flags))
3046                                        continue;
3047                                /* This is where we read from */
3048                                any_working = 1;
3049                                rdev = conf->mirrors[d].rdev;
3050                                sector = r10_bio->devs[j].addr;
3051
3052                                if (is_badblock(rdev, sector, max_sync,
3053                                                &first_bad, &bad_sectors)) {
3054                                        if (first_bad > sector)
3055                                                max_sync = first_bad - sector;
3056                                        else {
3057                                                bad_sectors -= (sector
3058                                                                - first_bad);
3059                                                if (max_sync > bad_sectors)
3060                                                        max_sync = bad_sectors;
3061                                                continue;
3062                                        }
3063                                }
3064                                bio = r10_bio->devs[0].bio;
3065                                bio->bi_next = biolist;
3066                                biolist = bio;
3067                                bio->bi_private = r10_bio;
3068                                bio->bi_end_io = end_sync_read;
3069                                bio->bi_rw = READ;
3070                                from_addr = r10_bio->devs[j].addr;
3071                                bio->bi_sector = from_addr + rdev->data_offset;
3072                                bio->bi_bdev = rdev->bdev;
3073                                atomic_inc(&rdev->nr_pending);
3074                                /* and we write to 'i' (if not in_sync) */
3075
3076                                for (k=0; k<conf->copies; k++)
3077                                        if (r10_bio->devs[k].devnum == i)
3078                                                break;
3079                                BUG_ON(k == conf->copies);
3080                                to_addr = r10_bio->devs[k].addr;
3081                                r10_bio->devs[0].devnum = d;
3082                                r10_bio->devs[0].addr = from_addr;
3083                                r10_bio->devs[1].devnum = i;
3084                                r10_bio->devs[1].addr = to_addr;
3085
3086                                rdev = mirror->rdev;
3087                                if (!test_bit(In_sync, &rdev->flags)) {
3088                                        bio = r10_bio->devs[1].bio;
3089                                        bio->bi_next = biolist;
3090                                        biolist = bio;
3091                                        bio->bi_private = r10_bio;
3092                                        bio->bi_end_io = end_sync_write;
3093                                        bio->bi_rw = WRITE;
3094                                        bio->bi_sector = to_addr
3095                                                + rdev->data_offset;
3096                                        bio->bi_bdev = rdev->bdev;
3097                                        atomic_inc(&r10_bio->remaining);
3098                                } else
3099                                        r10_bio->devs[1].bio->bi_end_io = NULL;
3100
3101                                /* and maybe write to replacement */
3102                                bio = r10_bio->devs[1].repl_bio;
3103                                if (bio)
3104                                        bio->bi_end_io = NULL;
3105                                rdev = mirror->replacement;
3106                                /* Note: if rdev != NULL, then bio
3107                                 * cannot be NULL as r10buf_pool_alloc will
3108                                 * have allocated it.
3109                                 * So the second test here is pointless.
3110                                 * But it keeps semantic-checkers happy, and
3111                                 * this comment keeps human reviewers
3112                                 * happy.
3113                                 */
3114                                if (rdev == NULL || bio == NULL ||
3115                                    test_bit(Faulty, &rdev->flags))
3116                                        break;
3117                                bio->bi_next = biolist;
3118                                biolist = bio;
3119                                bio->bi_private = r10_bio;
3120                                bio->bi_end_io = end_sync_write;
3121                                bio->bi_rw = WRITE;
3122                                bio->bi_sector = to_addr + rdev->data_offset;
3123                                bio->bi_bdev = rdev->bdev;
3124                                atomic_inc(&r10_bio->remaining);
3125                                break;
3126                        }
3127                        if (j == conf->copies) {
3128                                /* Cannot recover, so abort the recovery or
3129                                 * record a bad block */
3130                                put_buf(r10_bio);
3131                                if (rb2)
3132                                        atomic_dec(&rb2->remaining);
3133                                r10_bio = rb2;
3134                                if (any_working) {
3135                                        /* problem is that there are bad blocks
3136                                         * on other device(s)
3137                                         */
3138                                        int k;
3139                                        for (k = 0; k < conf->copies; k++)
3140                                                if (r10_bio->devs[k].devnum == i)
3141                                                        break;
3142                                        if (!test_bit(In_sync,
3143                                                      &mirror->rdev->flags)
3144                                            && !rdev_set_badblocks(
3145                                                    mirror->rdev,
3146                                                    r10_bio->devs[k].addr,
3147                                                    max_sync, 0))
3148                                                any_working = 0;
3149                                        if (mirror->replacement &&
3150                                            !rdev_set_badblocks(
3151                                                    mirror->replacement,
3152                                                    r10_bio->devs[k].addr,
3153                                                    max_sync, 0))
3154                                                any_working = 0;
3155                                }
3156                                if (!any_working)  {
3157                                        if (!test_and_set_bit(MD_RECOVERY_INTR,
3158                                                              &mddev->recovery))
3159                                                printk(KERN_INFO "md/raid10:%s: insufficient "
3160                                                       "working devices for recovery.\n",
3161                                                       mdname(mddev));
3162                                        mirror->recovery_disabled
3163                                                = mddev->recovery_disabled;
3164                                }
3165                                break;
3166                        }
3167                }
3168                if (biolist == NULL) {
3169                        while (r10_bio) {
3170                                struct r10bio *rb2 = r10_bio;
3171                                r10_bio = (struct r10bio*) rb2->master_bio;
3172                                rb2->master_bio = NULL;
3173                                put_buf(rb2);
3174                        }
3175                        goto giveup;
3176                }
3177        } else {
3178                /* resync. Schedule a read for every block at this virt offset */
3179                int count = 0;
3180
3181                bitmap_cond_end_sync(mddev->bitmap, sector_nr);
3182
3183                if (!bitmap_start_sync(mddev->bitmap, sector_nr,
3184                                       &sync_blocks, mddev->degraded) &&
3185                    !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED,
3186                                                 &mddev->recovery)) {
3187                        /* We can skip this block */
3188                        *skipped = 1;
3189                        return sync_blocks + sectors_skipped;
3190                }
3191                if (sync_blocks < max_sync)
3192                        max_sync = sync_blocks;
3193                r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
3194
3195                r10_bio->mddev = mddev;
3196                atomic_set(&r10_bio->remaining, 0);
3197                raise_barrier(conf, 0);
3198                conf->next_resync = sector_nr;
3199
3200                r10_bio->master_bio = NULL;
3201                r10_bio->sector = sector_nr;
3202                set_bit(R10BIO_IsSync, &r10_bio->state);
3203                raid10_find_phys(conf, r10_bio);
3204                r10_bio->sectors = (sector_nr | chunk_mask) - sector_nr + 1;
3205
3206                for (i = 0; i < conf->copies; i++) {
3207                        int d = r10_bio->devs[i].devnum;
3208                        sector_t first_bad, sector;
3209                        int bad_sectors;
3210
3211                        if (r10_bio->devs[i].repl_bio)
3212                                r10_bio->devs[i].repl_bio->bi_end_io = NULL;
3213
3214                        bio = r10_bio->devs[i].bio;
3215                        bio->bi_end_io = NULL;
3216                        clear_bit(BIO_UPTODATE, &bio->bi_flags);
3217                        if (conf->mirrors[d].rdev == NULL ||
3218                            test_bit(Faulty, &conf->mirrors[d].rdev->flags))
3219                                continue;
3220                        sector = r10_bio->devs[i].addr;
3221                        if (is_badblock(conf->mirrors[d].rdev,
3222                                        sector, max_sync,
3223                                        &first_bad, &bad_sectors)) {
3224                                if (first_bad > sector)
3225                                        max_sync = first_bad - sector;
3226                                else {
3227                                        bad_sectors -= (sector - first_bad);
3228                                        if (max_sync > bad_sectors)
3229                                                max_sync = bad_sectors;
3230                                        continue;
3231                                }
3232                        }
3233                        atomic_inc(&conf->mirrors[d].rdev->nr_pending);
3234                        atomic_inc(&r10_bio->remaining);
3235                        bio->bi_next = biolist;
3236                        biolist = bio;
3237                        bio->bi_private = r10_bio;
3238                        bio->bi_end_io = end_sync_read;
3239                        bio->bi_rw = READ;
3240                        bio->bi_sector = sector +
3241                                conf->mirrors[d].rdev->data_offset;
3242                        bio->bi_bdev = conf->mirrors[d].rdev->bdev;
3243                        count++;
3244
3245                        if (conf->mirrors[d].replacement == NULL ||
3246                            test_bit(Faulty,
3247                                     &conf->mirrors[d].replacement->flags))
3248                                continue;
3249
3250                        /* Need to set up for writing to the replacement */
3251                        bio = r10_bio->devs[i].repl_bio;
3252                        clear_bit(BIO_UPTODATE, &bio->bi_flags);
3253
3254                        sector = r10_bio->devs[i].addr;
3255                        atomic_inc(&conf->mirrors[d].rdev->nr_pending);
3256                        bio->bi_next = biolist;
3257                        biolist = bio;
3258                        bio->bi_private = r10_bio;
3259                        bio->bi_end_io = end_sync_write;
3260                        bio->bi_rw = WRITE;
3261                        bio->bi_sector = sector +
3262                                conf->mirrors[d].replacement->data_offset;
3263                        bio->bi_bdev = conf->mirrors[d].replacement->bdev;
3264                        count++;
3265                }
3266
3267                if (count < 2) {
3268                        for (i=0; i<conf->copies; i++) {
3269                                int d = r10_bio->devs[i].devnum;
3270                                if (r10_bio->devs[i].bio->bi_end_io)
3271                                        rdev_dec_pending(conf->mirrors[d].rdev,
3272                                                         mddev);
3273                                if (r10_bio->devs[i].repl_bio &&
3274                                    r10_bio->devs[i].repl_bio->bi_end_io)
3275                                        rdev_dec_pending(
3276                                                conf->mirrors[d].replacement,
3277                                                mddev);
3278                        }
3279                        put_buf(r10_bio);
3280                        biolist = NULL;
3281                        goto giveup;
3282                }
3283        }
3284
3285        for (bio = biolist; bio ; bio=bio->bi_next) {
3286
3287                bio->bi_flags &= ~(BIO_POOL_MASK - 1);
3288                if (bio->bi_end_io)
3289                        bio->bi_flags |= 1 << BIO_UPTODATE;
3290                bio->bi_vcnt = 0;
3291                bio->bi_idx = 0;
3292                bio->bi_phys_segments = 0;
3293                bio->bi_size = 0;
3294        }
3295
3296        nr_sectors = 0;
3297        if (sector_nr + max_sync < max_sector)
3298                max_sector = sector_nr + max_sync;
3299        do {
3300                struct page *page;
3301                int len = PAGE_SIZE;
3302                if (sector_nr + (len>>9) > max_sector)
3303                        len = (max_sector - sector_nr) << 9;
3304                if (len == 0)
3305                        break;
3306                for (bio= biolist ; bio ; bio=bio->bi_next) {
3307                        struct bio *bio2;
3308                        page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
3309                        if (bio_add_page(bio, page, len, 0))
3310                                continue;
3311
3312                        /* stop here */
3313                        bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
3314                        for (bio2 = biolist;
3315                             bio2 && bio2 != bio;
3316                             bio2 = bio2->bi_next) {
3317                                /* remove last page from this bio */
3318                                bio2->bi_vcnt--;
3319                                bio2->bi_size -= len;
3320                                bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
3321                        }
3322                        goto bio_full;
3323                }
3324                nr_sectors += len>>9;
3325                sector_nr += len>>9;
3326        } while (biolist->bi_vcnt < RESYNC_PAGES);
3327 bio_full:
3328        r10_bio->sectors = nr_sectors;
3329
3330        while (biolist) {
3331                bio = biolist;
3332                biolist = biolist->bi_next;
3333
3334                bio->bi_next = NULL;
3335                r10_bio = bio->bi_private;
3336                r10_bio->sectors = nr_sectors;
3337
3338                if (bio->bi_end_io == end_sync_read) {
3339                        md_sync_acct(bio->bi_bdev, nr_sectors);
3340                        generic_make_request(bio);
3341                }
3342        }
3343
3344        if (sectors_skipped)
3345                /* pretend they weren't skipped, it makes
3346                 * no important difference in this case
3347                 */
3348                md_done_sync(mddev, sectors_skipped, 1);
3349
3350        return sectors_skipped + nr_sectors;
3351 giveup:
3352        /* There is nowhere to write, so all non-sync
3353         * drives must be failed or in resync, all drives
3354         * have a bad block, so try the next chunk...
3355         */
3356        if (sector_nr + max_sync < max_sector)
3357                max_sector = sector_nr + max_sync;
3358
3359        sectors_skipped += (max_sector - sector_nr);
3360        chunks_skipped ++;
3361        sector_nr = max_sector;
3362        goto skipped;
3363}
3364
3365static sector_t
3366raid10_size(struct mddev *mddev, sector_t sectors, int raid_disks)
3367{
3368        sector_t size;
3369        struct r10conf *conf = mddev->private;
3370
3371        if (!raid_disks)
3372                raid_disks = min(conf->geo.raid_disks,
3373                                 conf->prev.raid_disks);
3374        if (!sectors)
3375                sectors = conf->dev_sectors;
3376
3377        size = sectors >> conf->geo.chunk_shift;
3378        sector_div(size, conf->geo.far_copies);
3379        size = size * raid_disks;
3380        sector_div(size, conf->geo.near_copies);
3381
3382        return size << conf->geo.chunk_shift;
3383}
3384
3385static void calc_sectors(struct r10conf *conf, sector_t size)
3386{
3387        /* Calculate the number of sectors-per-device that will
3388         * actually be used, and set conf->dev_sectors and
3389         * conf->stride
3390         */
3391
3392        size = size >> conf->geo.chunk_shift;
3393        sector_div(size, conf->geo.far_copies);
3394        size = size * conf->geo.raid_disks;
3395        sector_div(size, conf->geo.near_copies);
3396        /* 'size' is now the number of chunks in the array */
3397        /* calculate "used chunks per device" */
3398        size = size * conf->copies;
3399
3400        /* We need to round up when dividing by raid_disks to
3401         * get the stride size.
3402         */
3403        size = DIV_ROUND_UP_SECTOR_T(size, conf->geo.raid_disks);
3404
3405        conf->dev_sectors = size << conf->geo.chunk_shift;
3406
3407        if (conf->geo.far_offset)
3408                conf->geo.stride = 1 << conf->geo.chunk_shift;
3409        else {
3410                sector_div(size, conf->geo.far_copies);
3411                conf->geo.stride = size << conf->geo.chunk_shift;
3412        }
3413}
3414
3415enum geo_type {geo_new, geo_old, geo_start};
3416static int setup_geo(struct geom *geo, struct mddev *mddev, enum geo_type new)
3417{
3418        int nc, fc, fo;
3419        int layout, chunk, disks;
3420        switch (new) {
3421        case geo_old:
3422                layout = mddev->layout;
3423                chunk = mddev->chunk_sectors;
3424                disks = mddev->raid_disks - mddev->delta_disks;
3425                break;
3426        case geo_new:
3427                layout = mddev->new_layout;
3428                chunk = mddev->new_chunk_sectors;
3429                disks = mddev->raid_disks;
3430                break;
3431        default: /* avoid 'may be unused' warnings */
3432        case geo_start: /* new when starting reshape - raid_disks not
3433                         * updated yet. */
3434                layout = mddev->new_layout;
3435                chunk = mddev->new_chunk_sectors;
3436                disks = mddev->raid_disks + mddev->delta_disks;
3437                break;
3438        }
3439        if (layout >> 17)
3440                return -1;
3441        if (chunk < (PAGE_SIZE >> 9) ||
3442            !is_power_of_2(chunk))
3443                return -2;
3444        nc = layout & 255;
3445        fc = (layout >> 8) & 255;
3446        fo = layout & (1<<16);
3447        geo->raid_disks = disks;
3448        geo->near_copies = nc;
3449        geo->far_copies = fc;
3450        geo->far_offset = fo;
3451        geo->chunk_mask = chunk - 1;
3452        geo->chunk_shift = ffz(~chunk);
3453        return nc*fc;
3454}
3455
3456static struct r10conf *setup_conf(struct mddev *mddev)
3457{
3458        struct r10conf *conf = NULL;
3459        int err = -EINVAL;
3460        struct geom geo;
3461        int copies;
3462
3463        copies = setup_geo(&geo, mddev, geo_new);
3464
3465        if (copies == -2) {
3466                printk(KERN_ERR "md/raid10:%s: chunk size must be "
3467                       "at least PAGE_SIZE(%ld) and be a power of 2.\n",
3468                       mdname(mddev), PAGE_SIZE);
3469                goto out;
3470        }
3471
3472        if (copies < 2 || copies > mddev->raid_disks) {
3473                printk(KERN_ERR "md/raid10:%s: unsupported raid10 layout: 0x%8x\n",
3474                       mdname(mddev), mddev->new_layout);
3475                goto out;
3476        }
3477
3478        err = -ENOMEM;
3479        conf = kzalloc(sizeof(struct r10conf), GFP_KERNEL);
3480        if (!conf)
3481                goto out;
3482
3483        /* FIXME calc properly */
3484        conf->mirrors = kzalloc(sizeof(struct raid10_info)*(mddev->raid_disks +
3485                                                            max(0,mddev->delta_disks)),
3486                                GFP_KERNEL);
3487        if (!conf->mirrors)
3488                goto out;
3489
3490        conf->tmppage = alloc_page(GFP_KERNEL);
3491        if (!conf->tmppage)
3492                goto out;
3493
3494        conf->geo = geo;
3495        conf->copies = copies;
3496        conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
3497                                           r10bio_pool_free, conf);
3498        if (!conf->r10bio_pool)
3499                goto out;
3500
3501        calc_sectors(conf, mddev->dev_sectors);
3502        if (mddev->reshape_position == MaxSector) {
3503                conf->prev = conf->geo;
3504                conf->reshape_progress = MaxSector;
3505        } else {
3506                if (setup_geo(&conf->prev, mddev, geo_old) != conf->copies) {
3507                        err = -EINVAL;
3508                        goto out;
3509                }
3510                conf->reshape_progress = mddev->reshape_position;
3511                if (conf->prev.far_offset)
3512                        conf->prev.stride = 1 << conf->prev.chunk_shift;
3513                else
3514                        /* far_copies must be 1 */
3515                        conf->prev.stride = conf->dev_sectors;
3516        }
3517        spin_lock_init(&conf->device_lock);
3518        INIT_LIST_HEAD(&conf->retry_list);
3519
3520        spin_lock_init(&conf->resync_lock);
3521        init_waitqueue_head(&conf->wait_barrier);
3522
3523        conf->thread = md_register_thread(raid10d, mddev, "raid10");
3524        if (!conf->thread)
3525                goto out;
3526
3527        conf->mddev = mddev;
3528        return conf;
3529
3530 out:
3531        if (err == -ENOMEM)
3532                printk(KERN_ERR "md/raid10:%s: couldn't allocate memory.\n",
3533                       mdname(mddev));
3534        if (conf) {
3535                if (conf->r10bio_pool)
3536                        mempool_destroy(conf->r10bio_pool);
3537                kfree(conf->mirrors);
3538                safe_put_page(conf->tmppage);
3539                kfree(conf);
3540        }
3541        return ERR_PTR(err);
3542}
3543
3544static int run(struct mddev *mddev)
3545{
3546        struct r10conf *conf;
3547        int i, disk_idx, chunk_size;
3548        struct raid10_info *disk;
3549        struct md_rdev *rdev;
3550        sector_t size;
3551        sector_t min_offset_diff = 0;
3552        int first = 1;
3553        bool discard_supported = false;
3554
3555        if (mddev->private == NULL) {
3556                conf = setup_conf(mddev);
3557                if (IS_ERR(conf))
3558                        return PTR_ERR(conf);
3559                mddev->private = conf;
3560        }
3561        conf = mddev->private;
3562        if (!conf)
3563                goto out;
3564
3565        mddev->thread = conf->thread;
3566        conf->thread = NULL;
3567
3568        chunk_size = mddev->chunk_sectors << 9;
3569        if (mddev->queue) {
3570                blk_queue_max_discard_sectors(mddev->queue,
3571                                              mddev->chunk_sectors);
3572                blk_queue_io_min(mddev->queue, chunk_size);
3573                if (conf->geo.raid_disks % conf->geo.near_copies)
3574                        blk_queue_io_opt(mddev->queue, chunk_size * conf->geo.raid_disks);
3575                else
3576                        blk_queue_io_opt(mddev->queue, chunk_size *
3577                                         (conf->geo.raid_disks / conf->geo.near_copies));
3578        }
3579
3580        rdev_for_each(rdev, mddev) {
3581                long long diff;
3582                struct request_queue *q;
3583
3584                disk_idx = rdev->raid_disk;
3585                if (disk_idx < 0)
3586                        continue;
3587                if (disk_idx >= conf->geo.raid_disks &&
3588                    disk_idx >= conf->prev.raid_disks)
3589                        continue;
3590                disk = conf->mirrors + disk_idx;
3591
3592                if (test_bit(Replacement, &rdev->flags)) {
3593                        if (disk->replacement)
3594                                goto out_free_conf;
3595                        disk->replacement = rdev;
3596                } else {
3597                        if (disk->rdev)
3598                                goto out_free_conf;
3599                        disk->rdev = rdev;
3600                }
3601                q = bdev_get_queue(rdev->bdev);
3602                if (q->merge_bvec_fn)
3603                        mddev->merge_check_needed = 1;
3604                diff = (rdev->new_data_offset - rdev->data_offset);
3605                if (!mddev->reshape_backwards)
3606                        diff = -diff;
3607                if (diff < 0)
3608                        diff = 0;
3609                if (first || diff < min_offset_diff)
3610                        min_offset_diff = diff;
3611
3612                if (mddev->gendisk)
3613                        disk_stack_limits(mddev->gendisk, rdev->bdev,
3614                                          rdev->data_offset << 9);
3615
3616                disk->head_position = 0;
3617
3618                if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
3619                        discard_supported = true;
3620        }
3621
3622        if (mddev->queue) {
3623                if (discard_supported)
3624                        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
3625                                                mddev->queue);
3626                else
3627                        queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
3628                                                  mddev->queue);
3629        }
3630        /* need to check that every block has at least one working mirror */
3631        if (!enough(conf, -1)) {
3632                printk(KERN_ERR "md/raid10:%s: not enough operational mirrors.\n",
3633                       mdname(mddev));
3634                goto out_free_conf;
3635        }
3636
3637        if (conf->reshape_progress != MaxSector) {
3638                /* must ensure that shape change is supported */
3639                if (conf->geo.far_copies != 1 &&
3640                    conf->geo.far_offset == 0)
3641                        goto out_free_conf;
3642                if (conf->prev.far_copies != 1 &&
3643                    conf->geo.far_offset == 0)
3644                        goto out_free_conf;
3645        }
3646
3647        mddev->degraded = 0;
3648        for (i = 0;
3649             i < conf->geo.raid_disks
3650                     || i < conf->prev.raid_disks;
3651             i++) {
3652
3653                disk = conf->mirrors + i;
3654
3655                if (!disk->rdev && disk->replacement) {
3656                        /* The replacement is all we have - use it */
3657                        disk->rdev = disk->replacement;
3658                        disk->replacement = NULL;
3659                        clear_bit(Replacement, &disk->rdev->flags);
3660                }
3661
3662                if (!disk->rdev ||
3663                    !test_bit(In_sync, &disk->rdev->flags)) {
3664                        disk->head_position = 0;
3665                        mddev->degraded++;
3666                        if (disk->rdev)
3667                                conf->fullsync = 1;
3668                }
3669                disk->recovery_disabled = mddev->recovery_disabled - 1;
3670        }
3671
3672        if (mddev->recovery_cp != MaxSector)
3673                printk(KERN_NOTICE "md/raid10:%s: not clean"
3674                       " -- starting background reconstruction\n",
3675                       mdname(mddev));
3676        printk(KERN_INFO
3677                "md/raid10:%s: active with %d out of %d devices\n",
3678                mdname(mddev), conf->geo.raid_disks - mddev->degraded,
3679                conf->geo.raid_disks);
3680        /*
3681         * Ok, everything is just fine now
3682         */
3683        mddev->dev_sectors = conf->dev_sectors;
3684        size = raid10_size(mddev, 0, 0);
3685        md_set_array_sectors(mddev, size);
3686        mddev->resync_max_sectors = size;
3687
3688        if (mddev->queue) {
3689                int stripe = conf->geo.raid_disks *
3690                        ((mddev->chunk_sectors << 9) / PAGE_SIZE);
3691                mddev->queue->backing_dev_info.congested_fn = raid10_congested;
3692                mddev->queue->backing_dev_info.congested_data = mddev;
3693
3694                /* Calculate max read-ahead size.
3695                 * We need to readahead at least twice a whole stripe....
3696                 * maybe...
3697                 */
3698                stripe /= conf->geo.near_copies;
3699                if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
3700                        mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
3701                blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
3702        }
3703
3704
3705        if (md_integrity_register(mddev))
3706                goto out_free_conf;
3707
3708        if (conf->reshape_progress != MaxSector) {
3709                unsigned long before_length, after_length;
3710
3711                before_length = ((1 << conf->prev.chunk_shift) *
3712                                 conf->prev.far_copies);
3713                after_length = ((1 << conf->geo.chunk_shift) *
3714                                conf->geo.far_copies);
3715
3716                if (max(before_length, after_length) > min_offset_diff) {
3717                        /* This cannot work */
3718                        printk("md/raid10: offset difference not enough to continue reshape\n");
3719                        goto out_free_conf;
3720                }
3721                conf->offset_diff = min_offset_diff;
3722
3723                conf->reshape_safe = conf->reshape_progress;
3724                clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
3725                clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
3726                set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
3727                set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
3728                mddev->sync_thread = md_register_thread(md_do_sync, mddev,
3729                                                        "reshape");
3730        }
3731
3732        return 0;
3733
3734out_free_conf:
3735        md_unregister_thread(&mddev->thread);
3736        if (conf->r10bio_pool)
3737                mempool_destroy(conf->r10bio_pool);
3738        safe_put_page(conf->tmppage);
3739        kfree(conf->mirrors);
3740        kfree(conf);
3741        mddev->private = NULL;
3742out:
3743        return -EIO;
3744}
3745
3746static int stop(struct mddev *mddev)
3747{
3748        struct r10conf *conf = mddev->private;
3749
3750        raise_barrier(conf, 0);
3751        lower_barrier(conf);
3752
3753        md_unregister_thread(&mddev->thread);
3754        if (mddev->queue)
3755                /* the unplug fn references 'conf'*/
3756                blk_sync_queue(mddev->queue);
3757
3758        if (conf->r10bio_pool)
3759                mempool_destroy(conf->r10bio_pool);
3760        kfree(conf->mirrors);
3761        kfree(conf);
3762        mddev->private = NULL;
3763        return 0;
3764}
3765
3766static void raid10_quiesce(struct mddev *mddev, int state)
3767{
3768        struct r10conf *conf = mddev->private;
3769
3770        switch(state) {
3771        case 1:
3772                raise_barrier(conf, 0);
3773                break;
3774        case 0:
3775                lower_barrier(conf);
3776                break;
3777        }
3778}
3779
3780static int raid10_resize(struct mddev *mddev, sector_t sectors)
3781{
3782        /* Resize of 'far' arrays is not supported.
3783         * For 'near' and 'offset' arrays we can set the
3784         * number of sectors used to be an appropriate multiple
3785         * of the chunk size.
3786         * For 'offset', this is far_copies*chunksize.
3787         * For 'near' the multiplier is the LCM of
3788         * near_copies and raid_disks.
3789         * So if far_copies > 1 && !far_offset, fail.
3790         * Else find LCM(raid_disks, near_copy)*far_copies and
3791         * multiply by chunk_size.  Then round to this number.
3792         * This is mostly done by raid10_size()
3793         */
3794        struct r10conf *conf = mddev->private;
3795        sector_t oldsize, size;
3796
3797        if (mddev->reshape_position != MaxSector)
3798                return -EBUSY;
3799
3800        if (conf->geo.far_copies > 1 && !conf->geo.far_offset)
3801                return -EINVAL;
3802
3803        oldsize = raid10_size(mddev, 0, 0);
3804        size = raid10_size(mddev, sectors, 0);
3805        if (mddev->external_size &&
3806            mddev->array_sectors > size)
3807                return -EINVAL;
3808        if (mddev->bitmap) {
3809                int ret = bitmap_resize(mddev->bitmap, size, 0, 0);
3810                if (ret)
3811                        return ret;
3812        }
3813        md_set_array_sectors(mddev, size);
3814        set_capacity(mddev->gendisk, mddev->array_sectors);
3815        revalidate_disk(mddev->gendisk);
3816        if (sectors > mddev->dev_sectors &&
3817            mddev->recovery_cp > oldsize) {
3818                mddev->recovery_cp = oldsize;
3819                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3820        }
3821        calc_sectors(conf, sectors);
3822        mddev->dev_sectors = conf->dev_sectors;
3823        mddev->resync_max_sectors = size;
3824        return 0;
3825}
3826
3827static void *raid10_takeover_raid0(struct mddev *mddev)
3828{
3829        struct md_rdev *rdev;
3830        struct r10conf *conf;
3831
3832        if (mddev->degraded > 0) {
3833                printk(KERN_ERR "md/raid10:%s: Error: degraded raid0!\n",
3834                       mdname(mddev));
3835                return ERR_PTR(-EINVAL);
3836        }
3837
3838        /* Set new parameters */
3839        mddev->new_level = 10;
3840        /* new layout: far_copies = 1, near_copies = 2 */
3841        mddev->new_layout = (1<<8) + 2;
3842        mddev->new_chunk_sectors = mddev->chunk_sectors;
3843        mddev->delta_disks = mddev->raid_disks;
3844        mddev->raid_disks *= 2;
3845        /* make sure it will be not marked as dirty */
3846        mddev->recovery_cp = MaxSector;
3847
3848        conf = setup_conf(mddev);
3849        if (!IS_ERR(conf)) {
3850                rdev_for_each(rdev, mddev)
3851                        if (rdev->raid_disk >= 0)
3852                                rdev->new_raid_disk = rdev->raid_disk * 2;
3853                conf->barrier = 1;
3854        }
3855
3856        return conf;
3857}
3858
3859static void *raid10_takeover(struct mddev *mddev)
3860{
3861        struct r0conf *raid0_conf;
3862
3863        /* raid10 can take over:
3864         *  raid0 - providing it has only two drives
3865         */
3866        if (mddev->level == 0) {
3867                /* for raid0 takeover only one zone is supported */
3868                raid0_conf = mddev->private;
3869                if (raid0_conf->nr_strip_zones > 1) {
3870                        printk(KERN_ERR "md/raid10:%s: cannot takeover raid 0"
3871                               " with more than one zone.\n",
3872                               mdname(mddev));
3873                        return ERR_PTR(-EINVAL);
3874                }
3875                return raid10_takeover_raid0(mddev);
3876        }
3877        return ERR_PTR(-EINVAL);
3878}
3879
3880static int raid10_check_reshape(struct mddev *mddev)
3881{
3882        /* Called when there is a request to change
3883         * - layout (to ->new_layout)
3884         * - chunk size (to ->new_chunk_sectors)
3885         * - raid_disks (by delta_disks)
3886         * or when trying to restart a reshape that was ongoing.
3887         *
3888         * We need to validate the request and possibly allocate
3889         * space if that might be an issue later.
3890         *
3891         * Currently we reject any reshape of a 'far' mode array,
3892         * allow chunk size to change if new is generally acceptable,
3893         * allow raid_disks to increase, and allow
3894         * a switch between 'near' mode and 'offset' mode.
3895         */
3896        struct r10conf *conf = mddev->private;
3897        struct geom geo;
3898
3899        if (conf->geo.far_copies != 1 && !conf->geo.far_offset)
3900                return -EINVAL;
3901
3902        if (setup_geo(&geo, mddev, geo_start) != conf->copies)
3903                /* mustn't change number of copies */
3904                return -EINVAL;
3905        if (geo.far_copies > 1 && !geo.far_offset)
3906                /* Cannot switch to 'far' mode */
3907                return -EINVAL;
3908
3909        if (mddev->array_sectors & geo.chunk_mask)
3910                        /* not factor of array size */
3911                        return -EINVAL;
3912
3913        if (!enough(conf, -1))
3914                return -EINVAL;
3915
3916        kfree(conf->mirrors_new);
3917        conf->mirrors_new = NULL;
3918        if (mddev->delta_disks > 0) {
3919                /* allocate new 'mirrors' list */
3920                conf->mirrors_new = kzalloc(
3921                        sizeof(struct raid10_info)
3922                        *(mddev->raid_disks +
3923                          mddev->delta_disks),
3924                        GFP_KERNEL);
3925                if (!conf->mirrors_new)
3926                        return -ENOMEM;
3927        }
3928        return 0;
3929}
3930
3931/*
3932 * Need to check if array has failed when deciding whether to:
3933 *  - start an array
3934 *  - remove non-faulty devices
3935 *  - add a spare
3936 *  - allow a reshape
3937 * This determination is simple when no reshape is happening.
3938 * However if there is a reshape, we need to carefully check
3939 * both the before and after sections.
3940 * This is because some failed devices may only affect one
3941 * of the two sections, and some non-in_sync devices may
3942 * be insync in the section most affected by failed devices.
3943 */
3944static int calc_degraded(struct r10conf *conf)
3945{
3946        int degraded, degraded2;
3947        int i;
3948
3949        rcu_read_lock();
3950        degraded = 0;
3951        /* 'prev' section first */
3952        for (i = 0; i < conf->prev.raid_disks; i++) {
3953                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
3954                if (!rdev || test_bit(Faulty, &rdev->flags))
3955                        degraded++;
3956                else if (!test_bit(In_sync, &rdev->flags))
3957                        /* When we can reduce the number of devices in
3958                         * an array, this might not contribute to
3959                         * 'degraded'.  It does now.
3960                         */
3961                        degraded++;
3962        }
3963        rcu_read_unlock();
3964        if (conf->geo.raid_disks == conf->prev.raid_disks)
3965                return degraded;
3966        rcu_read_lock();
3967        degraded2 = 0;
3968        for (i = 0; i < conf->geo.raid_disks; i++) {
3969                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
3970                if (!rdev || test_bit(Faulty, &rdev->flags))
3971                        degraded2++;
3972                else if (!test_bit(In_sync, &rdev->flags)) {
3973                        /* If reshape is increasing the number of devices,
3974                         * this section has already been recovered, so
3975                         * it doesn't contribute to degraded.
3976                         * else it does.
3977                         */
3978                        if (conf->geo.raid_disks <= conf->prev.raid_disks)
3979                                degraded2++;
3980                }
3981        }
3982        rcu_read_unlock();
3983        if (degraded2 > degraded)
3984                return degraded2;
3985        return degraded;
3986}
3987
3988static int raid10_start_reshape(struct mddev *mddev)
3989{
3990        /* A 'reshape' has been requested. This commits
3991         * the various 'new' fields and sets MD_RECOVER_RESHAPE
3992         * This also checks if there are enough spares and adds them
3993         * to the array.
3994         * We currently require enough spares to make the final
3995         * array non-degraded.  We also require that the difference
3996         * between old and new data_offset - on each device - is
3997         * enough that we never risk over-writing.
3998         */
3999
4000        unsigned long before_length, after_length;
4001        sector_t min_offset_diff = 0;
4002        int first = 1;
4003        struct geom new;
4004        struct r10conf *conf = mddev->private;
4005        struct md_rdev *rdev;
4006        int spares = 0;
4007        int ret;
4008
4009        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
4010                return -EBUSY;
4011
4012        if (setup_geo(&new, mddev, geo_start) != conf->copies)
4013                return -EINVAL;
4014
4015        before_length = ((1 << conf->prev.chunk_shift) *
4016                         conf->prev.far_copies);
4017        after_length = ((1 << conf->geo.chunk_shift) *
4018                        conf->geo.far_copies);
4019
4020        rdev_for_each(rdev, mddev) {
4021                if (!test_bit(In_sync, &rdev->flags)
4022                    && !test_bit(Faulty, &rdev->flags))
4023                        spares++;
4024                if (rdev->raid_disk >= 0) {
4025                        long long diff = (rdev->new_data_offset
4026                                          - rdev->data_offset);
4027                        if (!mddev->reshape_backwards)
4028                                diff = -diff;
4029                        if (diff < 0)
4030                                diff = 0;
4031                        if (first || diff < min_offset_diff)
4032                                min_offset_diff = diff;
4033                }
4034        }
4035
4036        if (max(before_length, after_length) > min_offset_diff)
4037                return -EINVAL;
4038
4039        if (spares < mddev->delta_disks)
4040                return -EINVAL;
4041
4042        conf->offset_diff = min_offset_diff;
4043        spin_lock_irq(&conf->device_lock);
4044        if (conf->mirrors_new) {
4045                memcpy(conf->mirrors_new, conf->mirrors,
4046                       sizeof(struct raid10_info)*conf->prev.raid_disks);
4047                smp_mb();
4048                kfree(conf->mirrors_old); /* FIXME and elsewhere */
4049                conf->mirrors_old = conf->mirrors;
4050                conf->mirrors = conf->mirrors_new;
4051                conf->mirrors_new = NULL;
4052        }
4053        setup_geo(&conf->geo, mddev, geo_start);
4054        smp_mb();
4055        if (mddev->reshape_backwards) {
4056                sector_t size = raid10_size(mddev, 0, 0);
4057                if (size < mddev->array_sectors) {
4058                        spin_unlock_irq(&conf->device_lock);
4059                        printk(KERN_ERR "md/raid10:%s: array size must be reduce before number of disks\n",
4060                               mdname(mddev));
4061                        return -EINVAL;
4062                }
4063                mddev->resync_max_sectors = size;
4064                conf->reshape_progress = size;
4065        } else
4066                conf->reshape_progress = 0;
4067        spin_unlock_irq(&conf->device_lock);
4068
4069        if (mddev->delta_disks && mddev->bitmap) {
4070                ret = bitmap_resize(mddev->bitmap,
4071                                    raid10_size(mddev, 0,
4072                                                conf->geo.raid_disks),
4073                                    0, 0);
4074                if (ret)
4075                        goto abort;
4076        }
4077        if (mddev->delta_disks > 0) {
4078                rdev_for_each(rdev, mddev)
4079                        if (rdev->raid_disk < 0 &&
4080                            !test_bit(Faulty, &rdev->flags)) {
4081                                if (raid10_add_disk(mddev, rdev) == 0) {
4082                                        if (rdev->raid_disk >=
4083                                            conf->prev.raid_disks)
4084                                                set_bit(In_sync, &rdev->flags);
4085                                        else
4086                                                rdev->recovery_offset = 0;
4087
4088                                        if (sysfs_link_rdev(mddev, rdev))
4089                                                /* Failure here  is OK */;
4090                                }
4091                        } else if (rdev->raid_disk >= conf->prev.raid_disks
4092                                   && !test_bit(Faulty, &rdev->flags)) {
4093                                /* This is a spare that was manually added */
4094                                set_bit(In_sync, &rdev->flags);
4095                        }
4096        }
4097        /* When a reshape changes the number of devices,
4098         * ->degraded is measured against the larger of the
4099         * pre and  post numbers.
4100         */
4101        spin_lock_irq(&conf->device_lock);
4102        mddev->degraded = calc_degraded(conf);
4103        spin_unlock_irq(&conf->device_lock);
4104        mddev->raid_disks = conf->geo.raid_disks;
4105        mddev->reshape_position = conf->reshape_progress;
4106        set_bit(MD_CHANGE_DEVS, &mddev->flags);
4107
4108        clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4109        clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4110        set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4111        set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4112
4113        mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4114                                                "reshape");
4115        if (!mddev->sync_thread) {
4116                ret = -EAGAIN;
4117                goto abort;
4118        }
4119        conf->reshape_checkpoint = jiffies;
4120        md_wakeup_thread(mddev->sync_thread);
4121        md_new_event(mddev);
4122        return 0;
4123
4124abort:
4125        mddev->recovery = 0;
4126        spin_lock_irq(&conf->device_lock);
4127        conf->geo = conf->prev;
4128        mddev->raid_disks = conf->geo.raid_disks;
4129        rdev_for_each(rdev, mddev)
4130                rdev->new_data_offset = rdev->data_offset;
4131        smp_wmb();
4132        conf->reshape_progress = MaxSector;
4133        mddev->reshape_position = MaxSector;
4134        spin_unlock_irq(&conf->device_lock);
4135        return ret;
4136}
4137
4138/* Calculate the last device-address that could contain
4139 * any block from the chunk that includes the array-address 's'
4140 * and report the next address.
4141 * i.e. the address returned will be chunk-aligned and after
4142 * any data that is in the chunk containing 's'.
4143 */
4144static sector_t last_dev_address(sector_t s, struct geom *geo)
4145{
4146        s = (s | geo->chunk_mask) + 1;
4147        s >>= geo->chunk_shift;
4148        s *= geo->near_copies;
4149        s = DIV_ROUND_UP_SECTOR_T(s, geo->raid_disks);
4150        s *= geo->far_copies;
4151        s <<= geo->chunk_shift;
4152        return s;
4153}
4154
4155/* Calculate the first device-address that could contain
4156 * any block from the chunk that includes the array-address 's'.
4157 * This too will be the start of a chunk
4158 */
4159static sector_t first_dev_address(sector_t s, struct geom *geo)
4160{
4161        s >>= geo->chunk_shift;
4162        s *= geo->near_copies;
4163        sector_div(s, geo->raid_disks);
4164        s *= geo->far_copies;
4165        s <<= geo->chunk_shift;
4166        return s;
4167}
4168
4169static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
4170                                int *skipped)
4171{
4172        /* We simply copy at most one chunk (smallest of old and new)
4173         * at a time, possibly less if that exceeds RESYNC_PAGES,
4174         * or we hit a bad block or something.
4175         * This might mean we pause for normal IO in the middle of
4176         * a chunk, but that is not a problem was mddev->reshape_position
4177         * can record any location.
4178         *
4179         * If we will want to write to a location that isn't
4180         * yet recorded as 'safe' (i.e. in metadata on disk) then
4181         * we need to flush all reshape requests and update the metadata.
4182         *
4183         * When reshaping forwards (e.g. to more devices), we interpret
4184         * 'safe' as the earliest block which might not have been copied
4185         * down yet.  We divide this by previous stripe size and multiply
4186         * by previous stripe length to get lowest device offset that we
4187         * cannot write to yet.
4188         * We interpret 'sector_nr' as an address that we want to write to.
4189         * From this we use last_device_address() to find where we might
4190         * write to, and first_device_address on the  'safe' position.
4191         * If this 'next' write position is after the 'safe' position,
4192         * we must update the metadata to increase the 'safe' position.
4193         *
4194         * When reshaping backwards, we round in the opposite direction
4195         * and perform the reverse test:  next write position must not be
4196         * less than current safe position.
4197         *
4198         * In all this the minimum difference in data offsets
4199         * (conf->offset_diff - always positive) allows a bit of slack,
4200         * so next can be after 'safe', but not by more than offset_disk
4201         *
4202         * We need to prepare all the bios here before we start any IO
4203         * to ensure the size we choose is acceptable to all devices.
4204         * The means one for each copy for write-out and an extra one for
4205         * read-in.
4206         * We store the read-in bio in ->master_bio and the others in
4207         * ->devs[x].bio and ->devs[x].repl_bio.
4208         */
4209        struct r10conf *conf = mddev->private;
4210        struct r10bio *r10_bio;
4211        sector_t next, safe, last;
4212        int max_sectors;
4213        int nr_sectors;
4214        int s;
4215        struct md_rdev *rdev;
4216        int need_flush = 0;
4217        struct bio *blist;
4218        struct bio *bio, *read_bio;
4219        int sectors_done = 0;
4220
4221        if (sector_nr == 0) {
4222                /* If restarting in the middle, skip the initial sectors */
4223                if (mddev->reshape_backwards &&
4224                    conf->reshape_progress < raid10_size(mddev, 0, 0)) {
4225                        sector_nr = (raid10_size(mddev, 0, 0)
4226                                     - conf->reshape_progress);
4227                } else if (!mddev->reshape_backwards &&
4228                           conf->reshape_progress > 0)
4229                        sector_nr = conf->reshape_progress;
4230                if (sector_nr) {
4231                        mddev->curr_resync_completed = sector_nr;
4232                        sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4233                        *skipped = 1;
4234                        return sector_nr;
4235                }
4236        }
4237
4238        /* We don't use sector_nr to track where we are up to
4239         * as that doesn't work well for ->reshape_backwards.
4240         * So just use ->reshape_progress.
4241         */
4242        if (mddev->reshape_backwards) {
4243                /* 'next' is the earliest device address that we might
4244                 * write to for this chunk in the new layout
4245                 */
4246                next = first_dev_address(conf->reshape_progress - 1,
4247                                         &conf->geo);
4248
4249                /* 'safe' is the last device address that we might read from
4250                 * in the old layout after a restart
4251                 */
4252                safe = last_dev_address(conf->reshape_safe - 1,
4253                                        &conf->prev);
4254
4255                if (next + conf->offset_diff < safe)
4256                        need_flush = 1;
4257
4258                last = conf->reshape_progress - 1;
4259                sector_nr = last & ~(sector_t)(conf->geo.chunk_mask
4260                                               & conf->prev.chunk_mask);
4261                if (sector_nr + RESYNC_BLOCK_SIZE/512 < last)
4262                        sector_nr = last + 1 - RESYNC_BLOCK_SIZE/512;
4263        } else {
4264                /* 'next' is after the last device address that we
4265                 * might write to for this chunk in the new layout
4266                 */
4267                next = last_dev_address(conf->reshape_progress, &conf->geo);
4268
4269                /* 'safe' is the earliest device address that we might
4270                 * read from in the old layout after a restart
4271                 */
4272                safe = first_dev_address(conf->reshape_safe, &conf->prev);
4273
4274                /* Need to update metadata if 'next' might be beyond 'safe'
4275                 * as that would possibly corrupt data
4276                 */
4277                if (next > safe + conf->offset_diff)
4278                        need_flush = 1;
4279
4280                sector_nr = conf->reshape_progress;
4281                last  = sector_nr | (conf->geo.chunk_mask
4282                                     & conf->prev.chunk_mask);
4283
4284                if (sector_nr + RESYNC_BLOCK_SIZE/512 <= last)
4285                        last = sector_nr + RESYNC_BLOCK_SIZE/512 - 1;
4286        }
4287
4288        if (need_flush ||
4289            time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4290                /* Need to update reshape_position in metadata */
4291                wait_barrier(conf);
4292                mddev->reshape_position = conf->reshape_progress;
4293                if (mddev->reshape_backwards)
4294                        mddev->curr_resync_completed = raid10_size(mddev, 0, 0)
4295                                - conf->reshape_progress;
4296                else
4297                        mddev->curr_resync_completed = conf->reshape_progress;
4298                conf->reshape_checkpoint = jiffies;
4299                set_bit(MD_CHANGE_DEVS, &mddev->flags);
4300                md_wakeup_thread(mddev->thread);
4301                wait_event(mddev->sb_wait, mddev->flags == 0 ||
4302                           kthread_should_stop());
4303                conf->reshape_safe = mddev->reshape_position;
4304                allow_barrier(conf);
4305        }
4306
4307read_more:
4308        /* Now schedule reads for blocks from sector_nr to last */
4309        r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
4310        raise_barrier(conf, sectors_done != 0);
4311        atomic_set(&r10_bio->remaining, 0);
4312        r10_bio->mddev = mddev;
4313        r10_bio->sector = sector_nr;
4314        set_bit(R10BIO_IsReshape, &r10_bio->state);
4315        r10_bio->sectors = last - sector_nr + 1;
4316        rdev = read_balance(conf, r10_bio, &max_sectors);
4317        BUG_ON(!test_bit(R10BIO_Previous, &r10_bio->state));
4318
4319        if (!rdev) {
4320                /* Cannot read from here, so need to record bad blocks
4321                 * on all the target devices.
4322                 */
4323                // FIXME
4324                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
4325                return sectors_done;
4326        }
4327
4328        read_bio = bio_alloc_mddev(GFP_KERNEL, RESYNC_PAGES, mddev);
4329
4330        read_bio->bi_bdev = rdev->bdev;
4331        read_bio->bi_sector = (r10_bio->devs[r10_bio->read_slot].addr
4332                               + rdev->data_offset);
4333        read_bio->bi_private = r10_bio;
4334        read_bio->bi_end_io = end_sync_read;
4335        read_bio->bi_rw = READ;
4336        read_bio->bi_flags &= ~(BIO_POOL_MASK - 1);
4337        read_bio->bi_flags |= 1 << BIO_UPTODATE;
4338        read_bio->bi_vcnt = 0;
4339        read_bio->bi_idx = 0;
4340        read_bio->bi_size = 0;
4341        r10_bio->master_bio = read_bio;
4342        r10_bio->read_slot = r10_bio->devs[r10_bio->read_slot].devnum;
4343
4344        /* Now find the locations in the new layout */
4345        __raid10_find_phys(&conf->geo, r10_bio);
4346
4347        blist = read_bio;
4348        read_bio->bi_next = NULL;
4349
4350        for (s = 0; s < conf->copies*2; s++) {
4351                struct bio *b;
4352                int d = r10_bio->devs[s/2].devnum;
4353                struct md_rdev *rdev2;
4354                if (s&1) {
4355                        rdev2 = conf->mirrors[d].replacement;
4356                        b = r10_bio->devs[s/2].repl_bio;
4357                } else {
4358                        rdev2 = conf->mirrors[d].rdev;
4359                        b = r10_bio->devs[s/2].bio;
4360                }
4361                if (!rdev2 || test_bit(Faulty, &rdev2->flags))
4362                        continue;
4363                b->bi_bdev = rdev2->bdev;
4364                b->bi_sector = r10_bio->devs[s/2].addr + rdev2->new_data_offset;
4365                b->bi_private = r10_bio;
4366                b->bi_end_io = end_reshape_write;
4367                b->bi_rw = WRITE;
4368                b->bi_flags &= ~(BIO_POOL_MASK - 1);
4369                b->bi_flags |= 1 << BIO_UPTODATE;
4370                b->bi_next = blist;
4371                b->bi_vcnt = 0;
4372                b->bi_idx = 0;
4373                b->bi_size = 0;
4374                blist = b;
4375        }
4376
4377        /* Now add as many pages as possible to all of these bios. */
4378
4379        nr_sectors = 0;
4380        for (s = 0 ; s < max_sectors; s += PAGE_SIZE >> 9) {
4381                struct page *page = r10_bio->devs[0].bio->bi_io_vec[s/(PAGE_SIZE>>9)].bv_page;
4382                int len = (max_sectors - s) << 9;
4383                if (len > PAGE_SIZE)
4384                        len = PAGE_SIZE;
4385                for (bio = blist; bio ; bio = bio->bi_next) {
4386                        struct bio *bio2;
4387                        if (bio_add_page(bio, page, len, 0))
4388                                continue;
4389
4390                        /* Didn't fit, must stop */
4391                        for (bio2 = blist;
4392                             bio2 && bio2 != bio;
4393                             bio2 = bio2->bi_next) {
4394                                /* Remove last page from this bio */
4395                                bio2->bi_vcnt--;
4396                                bio2->bi_size -= len;
4397                                bio2->bi_flags &= ~(1<<BIO_SEG_VALID);
4398                        }
4399                        goto bio_full;
4400                }
4401                sector_nr += len >> 9;
4402                nr_sectors += len >> 9;
4403        }
4404bio_full:
4405        r10_bio->sectors = nr_sectors;
4406
4407        /* Now submit the read */
4408        md_sync_acct(read_bio->bi_bdev, r10_bio->sectors);
4409        atomic_inc(&r10_bio->remaining);
4410        read_bio->bi_next = NULL;
4411        generic_make_request(read_bio);
4412        sector_nr += nr_sectors;
4413        sectors_done += nr_sectors;
4414        if (sector_nr <= last)
4415                goto read_more;
4416
4417        /* Now that we have done the whole section we can
4418         * update reshape_progress
4419         */
4420        if (mddev->reshape_backwards)
4421                conf->reshape_progress -= sectors_done;
4422        else
4423                conf->reshape_progress += sectors_done;
4424
4425        return sectors_done;
4426}
4427
4428static void end_reshape_request(struct r10bio *r10_bio);
4429static int handle_reshape_read_error(struct mddev *mddev,
4430                                     struct r10bio *r10_bio);
4431static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio)
4432{
4433        /* Reshape read completed.  Hopefully we have a block
4434         * to write out.
4435         * If we got a read error then we do sync 1-page reads from
4436         * elsewhere until we find the data - or give up.
4437         */
4438        struct r10conf *conf = mddev->private;
4439        int s;
4440
4441        if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
4442                if (handle_reshape_read_error(mddev, r10_bio) < 0) {
4443                        /* Reshape has been aborted */
4444                        md_done_sync(mddev, r10_bio->sectors, 0);
4445                        return;
4446                }
4447
4448        /* We definitely have the data in the pages, schedule the
4449         * writes.
4450         */
4451        atomic_set(&r10_bio->remaining, 1);
4452        for (s = 0; s < conf->copies*2; s++) {
4453                struct bio *b;
4454                int d = r10_bio->devs[s/2].devnum;
4455                struct md_rdev *rdev;
4456                if (s&1) {
4457                        rdev = conf->mirrors[d].replacement;
4458                        b = r10_bio->devs[s/2].repl_bio;
4459                } else {
4460                        rdev = conf->mirrors[d].rdev;
4461                        b = r10_bio->devs[s/2].bio;
4462                }
4463                if (!rdev || test_bit(Faulty, &rdev->flags))
4464                        continue;
4465                atomic_inc(&rdev->nr_pending);
4466                md_sync_acct(b->bi_bdev, r10_bio->sectors);
4467                atomic_inc(&r10_bio->remaining);
4468                b->bi_next = NULL;
4469                generic_make_request(b);
4470        }
4471        end_reshape_request(r10_bio);
4472}
4473
4474static void end_reshape(struct r10conf *conf)
4475{
4476        if (test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery))
4477                return;
4478
4479        spin_lock_irq(&conf->device_lock);
4480        conf->prev = conf->geo;
4481        md_finish_reshape(conf->mddev);
4482        smp_wmb();
4483        conf->reshape_progress = MaxSector;
4484        spin_unlock_irq(&conf->device_lock);
4485
4486        /* read-ahead size must cover two whole stripes, which is
4487         * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4488         */
4489        if (conf->mddev->queue) {
4490                int stripe = conf->geo.raid_disks *
4491                        ((conf->mddev->chunk_sectors << 9) / PAGE_SIZE);
4492                stripe /= conf->geo.near_copies;
4493                if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4494                        conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4495        }
4496        conf->fullsync = 0;
4497}
4498
4499
4500static int handle_reshape_read_error(struct mddev *mddev,
4501                                     struct r10bio *r10_bio)
4502{
4503        /* Use sync reads to get the blocks from somewhere else */
4504        int sectors = r10_bio->sectors;
4505        struct r10conf *conf = mddev->private;
4506        struct {
4507                struct r10bio r10_bio;
4508                struct r10dev devs[conf->copies];
4509        } on_stack;
4510        struct r10bio *r10b = &on_stack.r10_bio;
4511        int slot = 0;
4512        int idx = 0;
4513        struct bio_vec *bvec = r10_bio->master_bio->bi_io_vec;
4514
4515        r10b->sector = r10_bio->sector;
4516        __raid10_find_phys(&conf->prev, r10b);
4517
4518        while (sectors) {
4519                int s = sectors;
4520                int success = 0;
4521                int first_slot = slot;
4522
4523                if (s > (PAGE_SIZE >> 9))
4524                        s = PAGE_SIZE >> 9;
4525
4526                while (!success) {
4527                        int d = r10b->devs[slot].devnum;
4528                        struct md_rdev *rdev = conf->mirrors[d].rdev;
4529                        sector_t addr;
4530                        if (rdev == NULL ||
4531                            test_bit(Faulty, &rdev->flags) ||
4532                            !test_bit(In_sync, &rdev->flags))
4533                                goto failed;
4534
4535                        addr = r10b->devs[slot].addr + idx * PAGE_SIZE;
4536                        success = sync_page_io(rdev,
4537                                               addr,
4538                                               s << 9,
4539                                               bvec[idx].bv_page,
4540                                               READ, false);
4541                        if (success)
4542                                break;
4543                failed:
4544                        slot++;
4545                        if (slot >= conf->copies)
4546                                slot = 0;
4547                        if (slot == first_slot)
4548                                break;
4549                }
4550                if (!success) {
4551                        /* couldn't read this block, must give up */
4552                        set_bit(MD_RECOVERY_INTR,
4553                                &mddev->recovery);
4554                        return -EIO;
4555                }
4556                sectors -= s;
4557                idx++;
4558        }
4559        return 0;
4560}
4561
4562static void end_reshape_write(struct bio *bio, int error)
4563{
4564        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
4565        struct r10bio *r10_bio = bio->bi_private;
4566        struct mddev *mddev = r10_bio->mddev;
4567        struct r10conf *conf = mddev->private;
4568        int d;
4569        int slot;
4570        int repl;
4571        struct md_rdev *rdev = NULL;
4572
4573        d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
4574        if (repl)
4575                rdev = conf->mirrors[d].replacement;
4576        if (!rdev) {
4577                smp_mb();
4578                rdev = conf->mirrors[d].rdev;
4579        }
4580
4581        if (!uptodate) {
4582                /* FIXME should record badblock */
4583                md_error(mddev, rdev);
4584        }
4585
4586        rdev_dec_pending(rdev, mddev);
4587        end_reshape_request(r10_bio);
4588}
4589
4590static void end_reshape_request(struct r10bio *r10_bio)
4591{
4592        if (!atomic_dec_and_test(&r10_bio->remaining))
4593                return;
4594        md_done_sync(r10_bio->mddev, r10_bio->sectors, 1);
4595        bio_put(r10_bio->master_bio);
4596        put_buf(r10_bio);
4597}
4598
4599static void raid10_finish_reshape(struct mddev *mddev)
4600{
4601        struct r10conf *conf = mddev->private;
4602
4603        if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
4604                return;
4605
4606        if (mddev->delta_disks > 0) {
4607                sector_t size = raid10_size(mddev, 0, 0);
4608                md_set_array_sectors(mddev, size);
4609                if (mddev->recovery_cp > mddev->resync_max_sectors) {
4610                        mddev->recovery_cp = mddev->resync_max_sectors;
4611                        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4612                }
4613                mddev->resync_max_sectors = size;
4614                set_capacity(mddev->gendisk, mddev->array_sectors);
4615                revalidate_disk(mddev->gendisk);
4616        } else {
4617                int d;
4618                for (d = conf->geo.raid_disks ;
4619                     d < conf->geo.raid_disks - mddev->delta_disks;
4620                     d++) {
4621                        struct md_rdev *rdev = conf->mirrors[d].rdev;
4622                        if (rdev)
4623                                clear_bit(In_sync, &rdev->flags);
4624                        rdev = conf->mirrors[d].replacement;
4625                        if (rdev)
4626                                clear_bit(In_sync, &rdev->flags);
4627                }
4628        }
4629        mddev->layout = mddev->new_layout;
4630        mddev->chunk_sectors = 1 << conf->geo.chunk_shift;
4631        mddev->reshape_position = MaxSector;
4632        mddev->delta_disks = 0;
4633        mddev->reshape_backwards = 0;
4634}
4635
4636static struct md_personality raid10_personality =
4637{
4638        .name           = "raid10",
4639        .level          = 10,
4640        .owner          = THIS_MODULE,
4641        .make_request   = make_request,
4642        .run            = run,
4643        .stop           = stop,
4644        .status         = status,
4645        .error_handler  = error,
4646        .hot_add_disk   = raid10_add_disk,
4647        .hot_remove_disk= raid10_remove_disk,
4648        .spare_active   = raid10_spare_active,
4649        .sync_request   = sync_request,
4650        .quiesce        = raid10_quiesce,
4651        .size           = raid10_size,
4652        .resize         = raid10_resize,
4653        .takeover       = raid10_takeover,
4654        .check_reshape  = raid10_check_reshape,
4655        .start_reshape  = raid10_start_reshape,
4656        .finish_reshape = raid10_finish_reshape,
4657};
4658
4659static int __init raid_init(void)
4660{
4661        return register_md_personality(&raid10_personality);
4662}
4663
4664static void raid_exit(void)
4665{
4666        unregister_md_personality(&raid10_personality);
4667}
4668
4669module_init(raid_init);
4670module_exit(raid_exit);
4671MODULE_LICENSE("GPL");
4672MODULE_DESCRIPTION("RAID10 (striped mirror) personality for MD");
4673MODULE_ALIAS("md-personality-9"); /* RAID10 */
4674MODULE_ALIAS("md-raid10");
4675MODULE_ALIAS("md-level-10");
4676
4677module_param(max_queued_requests, int, S_IRUGO|S_IWUSR);
4678
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