linux/drivers/md/raid1.c
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   1/*
   2 * raid1.c : Multiple Devices driver for Linux
   3 *
   4 * Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
   5 *
   6 * Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   7 *
   8 * RAID-1 management functions.
   9 *
  10 * Better read-balancing code written by Mika Kuoppala <miku@iki.fi>, 2000
  11 *
  12 * Fixes to reconstruction by Jakob Ƙstergaard" <jakob@ostenfeld.dk>
  13 * Various fixes by Neil Brown <neilb@cse.unsw.edu.au>
  14 *
  15 * Changes by Peter T. Breuer <ptb@it.uc3m.es> 31/1/2003 to support
  16 * bitmapped intelligence in resync:
  17 *
  18 *      - bitmap marked during normal i/o
  19 *      - bitmap used to skip nondirty blocks during sync
  20 *
  21 * Additions to bitmap code, (C) 2003-2004 Paul Clements, SteelEye Technology:
  22 * - persistent bitmap code
  23 *
  24 * This program is free software; you can redistribute it and/or modify
  25 * it under the terms of the GNU General Public License as published by
  26 * the Free Software Foundation; either version 2, or (at your option)
  27 * any later version.
  28 *
  29 * You should have received a copy of the GNU General Public License
  30 * (for example /usr/src/linux/COPYING); if not, write to the Free
  31 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  32 */
  33
  34#include <linux/slab.h>
  35#include <linux/delay.h>
  36#include <linux/blkdev.h>
  37#include <linux/module.h>
  38#include <linux/seq_file.h>
  39#include <linux/ratelimit.h>
  40#include "md.h"
  41#include "raid1.h"
  42#include "bitmap.h"
  43
  44/*
  45 * Number of guaranteed r1bios in case of extreme VM load:
  46 */
  47#define NR_RAID1_BIOS 256
  48
  49/* when we get a read error on a read-only array, we redirect to another
  50 * device without failing the first device, or trying to over-write to
  51 * correct the read error.  To keep track of bad blocks on a per-bio
  52 * level, we store IO_BLOCKED in the appropriate 'bios' pointer
  53 */
  54#define IO_BLOCKED ((struct bio *)1)
  55/* When we successfully write to a known bad-block, we need to remove the
  56 * bad-block marking which must be done from process context.  So we record
  57 * the success by setting devs[n].bio to IO_MADE_GOOD
  58 */
  59#define IO_MADE_GOOD ((struct bio *)2)
  60
  61#define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
  62
  63/* When there are this many requests queue to be written by
  64 * the raid1 thread, we become 'congested' to provide back-pressure
  65 * for writeback.
  66 */
  67static int max_queued_requests = 1024;
  68
  69static void allow_barrier(struct r1conf *conf);
  70static void lower_barrier(struct r1conf *conf);
  71
  72static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
  73{
  74        struct pool_info *pi = data;
  75        int size = offsetof(struct r1bio, bios[pi->raid_disks]);
  76
  77        /* allocate a r1bio with room for raid_disks entries in the bios array */
  78        return kzalloc(size, gfp_flags);
  79}
  80
  81static void r1bio_pool_free(void *r1_bio, void *data)
  82{
  83        kfree(r1_bio);
  84}
  85
  86#define RESYNC_BLOCK_SIZE (64*1024)
  87//#define RESYNC_BLOCK_SIZE PAGE_SIZE
  88#define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
  89#define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
  90#define RESYNC_WINDOW (2048*1024)
  91
  92static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
  93{
  94        struct pool_info *pi = data;
  95        struct page *page;
  96        struct r1bio *r1_bio;
  97        struct bio *bio;
  98        int i, j;
  99
 100        r1_bio = r1bio_pool_alloc(gfp_flags, pi);
 101        if (!r1_bio)
 102                return NULL;
 103
 104        /*
 105         * Allocate bios : 1 for reading, n-1 for writing
 106         */
 107        for (j = pi->raid_disks ; j-- ; ) {
 108                bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
 109                if (!bio)
 110                        goto out_free_bio;
 111                r1_bio->bios[j] = bio;
 112        }
 113        /*
 114         * Allocate RESYNC_PAGES data pages and attach them to
 115         * the first bio.
 116         * If this is a user-requested check/repair, allocate
 117         * RESYNC_PAGES for each bio.
 118         */
 119        if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
 120                j = pi->raid_disks;
 121        else
 122                j = 1;
 123        while(j--) {
 124                bio = r1_bio->bios[j];
 125                for (i = 0; i < RESYNC_PAGES; i++) {
 126                        page = alloc_page(gfp_flags);
 127                        if (unlikely(!page))
 128                                goto out_free_pages;
 129
 130                        bio->bi_io_vec[i].bv_page = page;
 131                        bio->bi_vcnt = i+1;
 132                }
 133        }
 134        /* If not user-requests, copy the page pointers to all bios */
 135        if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
 136                for (i=0; i<RESYNC_PAGES ; i++)
 137                        for (j=1; j<pi->raid_disks; j++)
 138                                r1_bio->bios[j]->bi_io_vec[i].bv_page =
 139                                        r1_bio->bios[0]->bi_io_vec[i].bv_page;
 140        }
 141
 142        r1_bio->master_bio = NULL;
 143
 144        return r1_bio;
 145
 146out_free_pages:
 147        for (j=0 ; j < pi->raid_disks; j++)
 148                for (i=0; i < r1_bio->bios[j]->bi_vcnt ; i++)
 149                        put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
 150        j = -1;
 151out_free_bio:
 152        while (++j < pi->raid_disks)
 153                bio_put(r1_bio->bios[j]);
 154        r1bio_pool_free(r1_bio, data);
 155        return NULL;
 156}
 157
 158static void r1buf_pool_free(void *__r1_bio, void *data)
 159{
 160        struct pool_info *pi = data;
 161        int i,j;
 162        struct r1bio *r1bio = __r1_bio;
 163
 164        for (i = 0; i < RESYNC_PAGES; i++)
 165                for (j = pi->raid_disks; j-- ;) {
 166                        if (j == 0 ||
 167                            r1bio->bios[j]->bi_io_vec[i].bv_page !=
 168                            r1bio->bios[0]->bi_io_vec[i].bv_page)
 169                                safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
 170                }
 171        for (i=0 ; i < pi->raid_disks; i++)
 172                bio_put(r1bio->bios[i]);
 173
 174        r1bio_pool_free(r1bio, data);
 175}
 176
 177static void put_all_bios(struct r1conf *conf, struct r1bio *r1_bio)
 178{
 179        int i;
 180
 181        for (i = 0; i < conf->raid_disks * 2; i++) {
 182                struct bio **bio = r1_bio->bios + i;
 183                if (!BIO_SPECIAL(*bio))
 184                        bio_put(*bio);
 185                *bio = NULL;
 186        }
 187}
 188
 189static void free_r1bio(struct r1bio *r1_bio)
 190{
 191        struct r1conf *conf = r1_bio->mddev->private;
 192
 193        put_all_bios(conf, r1_bio);
 194        mempool_free(r1_bio, conf->r1bio_pool);
 195}
 196
 197static void put_buf(struct r1bio *r1_bio)
 198{
 199        struct r1conf *conf = r1_bio->mddev->private;
 200        int i;
 201
 202        for (i = 0; i < conf->raid_disks * 2; i++) {
 203                struct bio *bio = r1_bio->bios[i];
 204                if (bio->bi_end_io)
 205                        rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
 206        }
 207
 208        mempool_free(r1_bio, conf->r1buf_pool);
 209
 210        lower_barrier(conf);
 211}
 212
 213static void reschedule_retry(struct r1bio *r1_bio)
 214{
 215        unsigned long flags;
 216        struct mddev *mddev = r1_bio->mddev;
 217        struct r1conf *conf = mddev->private;
 218
 219        spin_lock_irqsave(&conf->device_lock, flags);
 220        list_add(&r1_bio->retry_list, &conf->retry_list);
 221        conf->nr_queued ++;
 222        spin_unlock_irqrestore(&conf->device_lock, flags);
 223
 224        wake_up(&conf->wait_barrier);
 225        md_wakeup_thread(mddev->thread);
 226}
 227
 228/*
 229 * raid_end_bio_io() is called when we have finished servicing a mirrored
 230 * operation and are ready to return a success/failure code to the buffer
 231 * cache layer.
 232 */
 233static void call_bio_endio(struct r1bio *r1_bio)
 234{
 235        struct bio *bio = r1_bio->master_bio;
 236        int done;
 237        struct r1conf *conf = r1_bio->mddev->private;
 238
 239        if (bio->bi_phys_segments) {
 240                unsigned long flags;
 241                spin_lock_irqsave(&conf->device_lock, flags);
 242                bio->bi_phys_segments--;
 243                done = (bio->bi_phys_segments == 0);
 244                spin_unlock_irqrestore(&conf->device_lock, flags);
 245        } else
 246                done = 1;
 247
 248        if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
 249                clear_bit(BIO_UPTODATE, &bio->bi_flags);
 250        if (done) {
 251                bio_endio(bio, 0);
 252                /*
 253                 * Wake up any possible resync thread that waits for the device
 254                 * to go idle.
 255                 */
 256                allow_barrier(conf);
 257        }
 258}
 259
 260static void raid_end_bio_io(struct r1bio *r1_bio)
 261{
 262        struct bio *bio = r1_bio->master_bio;
 263
 264        /* if nobody has done the final endio yet, do it now */
 265        if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 266                pr_debug("raid1: sync end %s on sectors %llu-%llu\n",
 267                         (bio_data_dir(bio) == WRITE) ? "write" : "read",
 268                         (unsigned long long) bio->bi_sector,
 269                         (unsigned long long) bio->bi_sector +
 270                         (bio->bi_size >> 9) - 1);
 271
 272                call_bio_endio(r1_bio);
 273        }
 274        free_r1bio(r1_bio);
 275}
 276
 277/*
 278 * Update disk head position estimator based on IRQ completion info.
 279 */
 280static inline void update_head_pos(int disk, struct r1bio *r1_bio)
 281{
 282        struct r1conf *conf = r1_bio->mddev->private;
 283
 284        conf->mirrors[disk].head_position =
 285                r1_bio->sector + (r1_bio->sectors);
 286}
 287
 288/*
 289 * Find the disk number which triggered given bio
 290 */
 291static int find_bio_disk(struct r1bio *r1_bio, struct bio *bio)
 292{
 293        int mirror;
 294        struct r1conf *conf = r1_bio->mddev->private;
 295        int raid_disks = conf->raid_disks;
 296
 297        for (mirror = 0; mirror < raid_disks * 2; mirror++)
 298                if (r1_bio->bios[mirror] == bio)
 299                        break;
 300
 301        BUG_ON(mirror == raid_disks * 2);
 302        update_head_pos(mirror, r1_bio);
 303
 304        return mirror;
 305}
 306
 307static void raid1_end_read_request(struct bio *bio, int error)
 308{
 309        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 310        struct r1bio *r1_bio = bio->bi_private;
 311        int mirror;
 312        struct r1conf *conf = r1_bio->mddev->private;
 313
 314        mirror = r1_bio->read_disk;
 315        /*
 316         * this branch is our 'one mirror IO has finished' event handler:
 317         */
 318        update_head_pos(mirror, r1_bio);
 319
 320        if (uptodate)
 321                set_bit(R1BIO_Uptodate, &r1_bio->state);
 322        else {
 323                /* If all other devices have failed, we want to return
 324                 * the error upwards rather than fail the last device.
 325                 * Here we redefine "uptodate" to mean "Don't want to retry"
 326                 */
 327                unsigned long flags;
 328                spin_lock_irqsave(&conf->device_lock, flags);
 329                if (r1_bio->mddev->degraded == conf->raid_disks ||
 330                    (r1_bio->mddev->degraded == conf->raid_disks-1 &&
 331                     !test_bit(Faulty, &conf->mirrors[mirror].rdev->flags)))
 332                        uptodate = 1;
 333                spin_unlock_irqrestore(&conf->device_lock, flags);
 334        }
 335
 336        if (uptodate) {
 337                raid_end_bio_io(r1_bio);
 338                rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 339        } else {
 340                /*
 341                 * oops, read error:
 342                 */
 343                char b[BDEVNAME_SIZE];
 344                printk_ratelimited(
 345                        KERN_ERR "md/raid1:%s: %s: "
 346                        "rescheduling sector %llu\n",
 347                        mdname(conf->mddev),
 348                        bdevname(conf->mirrors[mirror].rdev->bdev,
 349                                 b),
 350                        (unsigned long long)r1_bio->sector);
 351                set_bit(R1BIO_ReadError, &r1_bio->state);
 352                reschedule_retry(r1_bio);
 353                /* don't drop the reference on read_disk yet */
 354        }
 355}
 356
 357static void close_write(struct r1bio *r1_bio)
 358{
 359        /* it really is the end of this request */
 360        if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
 361                /* free extra copy of the data pages */
 362                int i = r1_bio->behind_page_count;
 363                while (i--)
 364                        safe_put_page(r1_bio->behind_bvecs[i].bv_page);
 365                kfree(r1_bio->behind_bvecs);
 366                r1_bio->behind_bvecs = NULL;
 367        }
 368        /* clear the bitmap if all writes complete successfully */
 369        bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
 370                        r1_bio->sectors,
 371                        !test_bit(R1BIO_Degraded, &r1_bio->state),
 372                        test_bit(R1BIO_BehindIO, &r1_bio->state));
 373        md_write_end(r1_bio->mddev);
 374}
 375
 376static void r1_bio_write_done(struct r1bio *r1_bio)
 377{
 378        if (!atomic_dec_and_test(&r1_bio->remaining))
 379                return;
 380
 381        if (test_bit(R1BIO_WriteError, &r1_bio->state))
 382                reschedule_retry(r1_bio);
 383        else {
 384                close_write(r1_bio);
 385                if (test_bit(R1BIO_MadeGood, &r1_bio->state))
 386                        reschedule_retry(r1_bio);
 387                else
 388                        raid_end_bio_io(r1_bio);
 389        }
 390}
 391
 392static void raid1_end_write_request(struct bio *bio, int error)
 393{
 394        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 395        struct r1bio *r1_bio = bio->bi_private;
 396        int mirror, behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
 397        struct r1conf *conf = r1_bio->mddev->private;
 398        struct bio *to_put = NULL;
 399
 400        mirror = find_bio_disk(r1_bio, bio);
 401
 402        /*
 403         * 'one mirror IO has finished' event handler:
 404         */
 405        if (!uptodate) {
 406                set_bit(WriteErrorSeen,
 407                        &conf->mirrors[mirror].rdev->flags);
 408                if (!test_and_set_bit(WantReplacement,
 409                                      &conf->mirrors[mirror].rdev->flags))
 410                        set_bit(MD_RECOVERY_NEEDED, &
 411                                conf->mddev->recovery);
 412
 413                set_bit(R1BIO_WriteError, &r1_bio->state);
 414        } else {
 415                /*
 416                 * Set R1BIO_Uptodate in our master bio, so that we
 417                 * will return a good error code for to the higher
 418                 * levels even if IO on some other mirrored buffer
 419                 * fails.
 420                 *
 421                 * The 'master' represents the composite IO operation
 422                 * to user-side. So if something waits for IO, then it
 423                 * will wait for the 'master' bio.
 424                 */
 425                sector_t first_bad;
 426                int bad_sectors;
 427
 428                r1_bio->bios[mirror] = NULL;
 429                to_put = bio;
 430                set_bit(R1BIO_Uptodate, &r1_bio->state);
 431
 432                /* Maybe we can clear some bad blocks. */
 433                if (is_badblock(conf->mirrors[mirror].rdev,
 434                                r1_bio->sector, r1_bio->sectors,
 435                                &first_bad, &bad_sectors)) {
 436                        r1_bio->bios[mirror] = IO_MADE_GOOD;
 437                        set_bit(R1BIO_MadeGood, &r1_bio->state);
 438                }
 439        }
 440
 441        if (behind) {
 442                if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
 443                        atomic_dec(&r1_bio->behind_remaining);
 444
 445                /*
 446                 * In behind mode, we ACK the master bio once the I/O
 447                 * has safely reached all non-writemostly
 448                 * disks. Setting the Returned bit ensures that this
 449                 * gets done only once -- we don't ever want to return
 450                 * -EIO here, instead we'll wait
 451                 */
 452                if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
 453                    test_bit(R1BIO_Uptodate, &r1_bio->state)) {
 454                        /* Maybe we can return now */
 455                        if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 456                                struct bio *mbio = r1_bio->master_bio;
 457                                pr_debug("raid1: behind end write sectors"
 458                                         " %llu-%llu\n",
 459                                         (unsigned long long) mbio->bi_sector,
 460                                         (unsigned long long) mbio->bi_sector +
 461                                         (mbio->bi_size >> 9) - 1);
 462                                call_bio_endio(r1_bio);
 463                        }
 464                }
 465        }
 466        if (r1_bio->bios[mirror] == NULL)
 467                rdev_dec_pending(conf->mirrors[mirror].rdev,
 468                                 conf->mddev);
 469
 470        /*
 471         * Let's see if all mirrored write operations have finished
 472         * already.
 473         */
 474        r1_bio_write_done(r1_bio);
 475
 476        if (to_put)
 477                bio_put(to_put);
 478}
 479
 480
 481/*
 482 * This routine returns the disk from which the requested read should
 483 * be done. There is a per-array 'next expected sequential IO' sector
 484 * number - if this matches on the next IO then we use the last disk.
 485 * There is also a per-disk 'last know head position' sector that is
 486 * maintained from IRQ contexts, both the normal and the resync IO
 487 * completion handlers update this position correctly. If there is no
 488 * perfect sequential match then we pick the disk whose head is closest.
 489 *
 490 * If there are 2 mirrors in the same 2 devices, performance degrades
 491 * because position is mirror, not device based.
 492 *
 493 * The rdev for the device selected will have nr_pending incremented.
 494 */
 495static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sectors)
 496{
 497        const sector_t this_sector = r1_bio->sector;
 498        int sectors;
 499        int best_good_sectors;
 500        int best_disk, best_dist_disk, best_pending_disk;
 501        int has_nonrot_disk;
 502        int disk;
 503        sector_t best_dist;
 504        unsigned int min_pending;
 505        struct md_rdev *rdev;
 506        int choose_first;
 507        int choose_next_idle;
 508
 509        rcu_read_lock();
 510        /*
 511         * Check if we can balance. We can balance on the whole
 512         * device if no resync is going on, or below the resync window.
 513         * We take the first readable disk when above the resync window.
 514         */
 515 retry:
 516        sectors = r1_bio->sectors;
 517        best_disk = -1;
 518        best_dist_disk = -1;
 519        best_dist = MaxSector;
 520        best_pending_disk = -1;
 521        min_pending = UINT_MAX;
 522        best_good_sectors = 0;
 523        has_nonrot_disk = 0;
 524        choose_next_idle = 0;
 525
 526        if (conf->mddev->recovery_cp < MaxSector &&
 527            (this_sector + sectors >= conf->next_resync))
 528                choose_first = 1;
 529        else
 530                choose_first = 0;
 531
 532        for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) {
 533                sector_t dist;
 534                sector_t first_bad;
 535                int bad_sectors;
 536                unsigned int pending;
 537                bool nonrot;
 538
 539                rdev = rcu_dereference(conf->mirrors[disk].rdev);
 540                if (r1_bio->bios[disk] == IO_BLOCKED
 541                    || rdev == NULL
 542                    || test_bit(Unmerged, &rdev->flags)
 543                    || test_bit(Faulty, &rdev->flags))
 544                        continue;
 545                if (!test_bit(In_sync, &rdev->flags) &&
 546                    rdev->recovery_offset < this_sector + sectors)
 547                        continue;
 548                if (test_bit(WriteMostly, &rdev->flags)) {
 549                        /* Don't balance among write-mostly, just
 550                         * use the first as a last resort */
 551                        if (best_disk < 0) {
 552                                if (is_badblock(rdev, this_sector, sectors,
 553                                                &first_bad, &bad_sectors)) {
 554                                        if (first_bad < this_sector)
 555                                                /* Cannot use this */
 556                                                continue;
 557                                        best_good_sectors = first_bad - this_sector;
 558                                } else
 559                                        best_good_sectors = sectors;
 560                                best_disk = disk;
 561                        }
 562                        continue;
 563                }
 564                /* This is a reasonable device to use.  It might
 565                 * even be best.
 566                 */
 567                if (is_badblock(rdev, this_sector, sectors,
 568                                &first_bad, &bad_sectors)) {
 569                        if (best_dist < MaxSector)
 570                                /* already have a better device */
 571                                continue;
 572                        if (first_bad <= this_sector) {
 573                                /* cannot read here. If this is the 'primary'
 574                                 * device, then we must not read beyond
 575                                 * bad_sectors from another device..
 576                                 */
 577                                bad_sectors -= (this_sector - first_bad);
 578                                if (choose_first && sectors > bad_sectors)
 579                                        sectors = bad_sectors;
 580                                if (best_good_sectors > sectors)
 581                                        best_good_sectors = sectors;
 582
 583                        } else {
 584                                sector_t good_sectors = first_bad - this_sector;
 585                                if (good_sectors > best_good_sectors) {
 586                                        best_good_sectors = good_sectors;
 587                                        best_disk = disk;
 588                                }
 589                                if (choose_first)
 590                                        break;
 591                        }
 592                        continue;
 593                } else
 594                        best_good_sectors = sectors;
 595
 596                nonrot = blk_queue_nonrot(bdev_get_queue(rdev->bdev));
 597                has_nonrot_disk |= nonrot;
 598                pending = atomic_read(&rdev->nr_pending);
 599                dist = abs(this_sector - conf->mirrors[disk].head_position);
 600                if (choose_first) {
 601                        best_disk = disk;
 602                        break;
 603                }
 604                /* Don't change to another disk for sequential reads */
 605                if (conf->mirrors[disk].next_seq_sect == this_sector
 606                    || dist == 0) {
 607                        int opt_iosize = bdev_io_opt(rdev->bdev) >> 9;
 608                        struct raid1_info *mirror = &conf->mirrors[disk];
 609
 610                        best_disk = disk;
 611                        /*
 612                         * If buffered sequential IO size exceeds optimal
 613                         * iosize, check if there is idle disk. If yes, choose
 614                         * the idle disk. read_balance could already choose an
 615                         * idle disk before noticing it's a sequential IO in
 616                         * this disk. This doesn't matter because this disk
 617                         * will idle, next time it will be utilized after the
 618                         * first disk has IO size exceeds optimal iosize. In
 619                         * this way, iosize of the first disk will be optimal
 620                         * iosize at least. iosize of the second disk might be
 621                         * small, but not a big deal since when the second disk
 622                         * starts IO, the first disk is likely still busy.
 623                         */
 624                        if (nonrot && opt_iosize > 0 &&
 625                            mirror->seq_start != MaxSector &&
 626                            mirror->next_seq_sect > opt_iosize &&
 627                            mirror->next_seq_sect - opt_iosize >=
 628                            mirror->seq_start) {
 629                                choose_next_idle = 1;
 630                                continue;
 631                        }
 632                        break;
 633                }
 634                /* If device is idle, use it */
 635                if (pending == 0) {
 636                        best_disk = disk;
 637                        break;
 638                }
 639
 640                if (choose_next_idle)
 641                        continue;
 642
 643                if (min_pending > pending) {
 644                        min_pending = pending;
 645                        best_pending_disk = disk;
 646                }
 647
 648                if (dist < best_dist) {
 649                        best_dist = dist;
 650                        best_dist_disk = disk;
 651                }
 652        }
 653
 654        /*
 655         * If all disks are rotational, choose the closest disk. If any disk is
 656         * non-rotational, choose the disk with less pending request even the
 657         * disk is rotational, which might/might not be optimal for raids with
 658         * mixed ratation/non-rotational disks depending on workload.
 659         */
 660        if (best_disk == -1) {
 661                if (has_nonrot_disk)
 662                        best_disk = best_pending_disk;
 663                else
 664                        best_disk = best_dist_disk;
 665        }
 666
 667        if (best_disk >= 0) {
 668                rdev = rcu_dereference(conf->mirrors[best_disk].rdev);
 669                if (!rdev)
 670                        goto retry;
 671                atomic_inc(&rdev->nr_pending);
 672                if (test_bit(Faulty, &rdev->flags)) {
 673                        /* cannot risk returning a device that failed
 674                         * before we inc'ed nr_pending
 675                         */
 676                        rdev_dec_pending(rdev, conf->mddev);
 677                        goto retry;
 678                }
 679                sectors = best_good_sectors;
 680
 681                if (conf->mirrors[best_disk].next_seq_sect != this_sector)
 682                        conf->mirrors[best_disk].seq_start = this_sector;
 683
 684                conf->mirrors[best_disk].next_seq_sect = this_sector + sectors;
 685        }
 686        rcu_read_unlock();
 687        *max_sectors = sectors;
 688
 689        return best_disk;
 690}
 691
 692static int raid1_mergeable_bvec(struct request_queue *q,
 693                                struct bvec_merge_data *bvm,
 694                                struct bio_vec *biovec)
 695{
 696        struct mddev *mddev = q->queuedata;
 697        struct r1conf *conf = mddev->private;
 698        sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 699        int max = biovec->bv_len;
 700
 701        if (mddev->merge_check_needed) {
 702                int disk;
 703                rcu_read_lock();
 704                for (disk = 0; disk < conf->raid_disks * 2; disk++) {
 705                        struct md_rdev *rdev = rcu_dereference(
 706                                conf->mirrors[disk].rdev);
 707                        if (rdev && !test_bit(Faulty, &rdev->flags)) {
 708                                struct request_queue *q =
 709                                        bdev_get_queue(rdev->bdev);
 710                                if (q->merge_bvec_fn) {
 711                                        bvm->bi_sector = sector +
 712                                                rdev->data_offset;
 713                                        bvm->bi_bdev = rdev->bdev;
 714                                        max = min(max, q->merge_bvec_fn(
 715                                                          q, bvm, biovec));
 716                                }
 717                        }
 718                }
 719                rcu_read_unlock();
 720        }
 721        return max;
 722
 723}
 724
 725int md_raid1_congested(struct mddev *mddev, int bits)
 726{
 727        struct r1conf *conf = mddev->private;
 728        int i, ret = 0;
 729
 730        if ((bits & (1 << BDI_async_congested)) &&
 731            conf->pending_count >= max_queued_requests)
 732                return 1;
 733
 734        rcu_read_lock();
 735        for (i = 0; i < conf->raid_disks * 2; i++) {
 736                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
 737                if (rdev && !test_bit(Faulty, &rdev->flags)) {
 738                        struct request_queue *q = bdev_get_queue(rdev->bdev);
 739
 740                        BUG_ON(!q);
 741
 742                        /* Note the '|| 1' - when read_balance prefers
 743                         * non-congested targets, it can be removed
 744                         */
 745                        if ((bits & (1<<BDI_async_congested)) || 1)
 746                                ret |= bdi_congested(&q->backing_dev_info, bits);
 747                        else
 748                                ret &= bdi_congested(&q->backing_dev_info, bits);
 749                }
 750        }
 751        rcu_read_unlock();
 752        return ret;
 753}
 754EXPORT_SYMBOL_GPL(md_raid1_congested);
 755
 756static int raid1_congested(void *data, int bits)
 757{
 758        struct mddev *mddev = data;
 759
 760        return mddev_congested(mddev, bits) ||
 761                md_raid1_congested(mddev, bits);
 762}
 763
 764static void flush_pending_writes(struct r1conf *conf)
 765{
 766        /* Any writes that have been queued but are awaiting
 767         * bitmap updates get flushed here.
 768         */
 769        spin_lock_irq(&conf->device_lock);
 770
 771        if (conf->pending_bio_list.head) {
 772                struct bio *bio;
 773                bio = bio_list_get(&conf->pending_bio_list);
 774                conf->pending_count = 0;
 775                spin_unlock_irq(&conf->device_lock);
 776                /* flush any pending bitmap writes to
 777                 * disk before proceeding w/ I/O */
 778                bitmap_unplug(conf->mddev->bitmap);
 779                wake_up(&conf->wait_barrier);
 780
 781                while (bio) { /* submit pending writes */
 782                        struct bio *next = bio->bi_next;
 783                        bio->bi_next = NULL;
 784                        if (unlikely((bio->bi_rw & REQ_DISCARD) &&
 785                            !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
 786                                /* Just ignore it */
 787                                bio_endio(bio, 0);
 788                        else
 789                                generic_make_request(bio);
 790                        bio = next;
 791                }
 792        } else
 793                spin_unlock_irq(&conf->device_lock);
 794}
 795
 796/* Barriers....
 797 * Sometimes we need to suspend IO while we do something else,
 798 * either some resync/recovery, or reconfigure the array.
 799 * To do this we raise a 'barrier'.
 800 * The 'barrier' is a counter that can be raised multiple times
 801 * to count how many activities are happening which preclude
 802 * normal IO.
 803 * We can only raise the barrier if there is no pending IO.
 804 * i.e. if nr_pending == 0.
 805 * We choose only to raise the barrier if no-one is waiting for the
 806 * barrier to go down.  This means that as soon as an IO request
 807 * is ready, no other operations which require a barrier will start
 808 * until the IO request has had a chance.
 809 *
 810 * So: regular IO calls 'wait_barrier'.  When that returns there
 811 *    is no backgroup IO happening,  It must arrange to call
 812 *    allow_barrier when it has finished its IO.
 813 * backgroup IO calls must call raise_barrier.  Once that returns
 814 *    there is no normal IO happeing.  It must arrange to call
 815 *    lower_barrier when the particular background IO completes.
 816 */
 817#define RESYNC_DEPTH 32
 818
 819static void raise_barrier(struct r1conf *conf)
 820{
 821        spin_lock_irq(&conf->resync_lock);
 822
 823        /* Wait until no block IO is waiting */
 824        wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
 825                            conf->resync_lock);
 826
 827        /* block any new IO from starting */
 828        conf->barrier++;
 829
 830        /* Now wait for all pending IO to complete */
 831        wait_event_lock_irq(conf->wait_barrier,
 832                            !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 833                            conf->resync_lock);
 834
 835        spin_unlock_irq(&conf->resync_lock);
 836}
 837
 838static void lower_barrier(struct r1conf *conf)
 839{
 840        unsigned long flags;
 841        BUG_ON(conf->barrier <= 0);
 842        spin_lock_irqsave(&conf->resync_lock, flags);
 843        conf->barrier--;
 844        spin_unlock_irqrestore(&conf->resync_lock, flags);
 845        wake_up(&conf->wait_barrier);
 846}
 847
 848static void wait_barrier(struct r1conf *conf)
 849{
 850        spin_lock_irq(&conf->resync_lock);
 851        if (conf->barrier) {
 852                conf->nr_waiting++;
 853                /* Wait for the barrier to drop.
 854                 * However if there are already pending
 855                 * requests (preventing the barrier from
 856                 * rising completely), and the
 857                 * pre-process bio queue isn't empty,
 858                 * then don't wait, as we need to empty
 859                 * that queue to get the nr_pending
 860                 * count down.
 861                 */
 862                wait_event_lock_irq(conf->wait_barrier,
 863                                    !conf->barrier ||
 864                                    (conf->nr_pending &&
 865                                     current->bio_list &&
 866                                     !bio_list_empty(current->bio_list)),
 867                                    conf->resync_lock);
 868                conf->nr_waiting--;
 869        }
 870        conf->nr_pending++;
 871        spin_unlock_irq(&conf->resync_lock);
 872}
 873
 874static void allow_barrier(struct r1conf *conf)
 875{
 876        unsigned long flags;
 877        spin_lock_irqsave(&conf->resync_lock, flags);
 878        conf->nr_pending--;
 879        spin_unlock_irqrestore(&conf->resync_lock, flags);
 880        wake_up(&conf->wait_barrier);
 881}
 882
 883static void freeze_array(struct r1conf *conf)
 884{
 885        /* stop syncio and normal IO and wait for everything to
 886         * go quite.
 887         * We increment barrier and nr_waiting, and then
 888         * wait until nr_pending match nr_queued+1
 889         * This is called in the context of one normal IO request
 890         * that has failed. Thus any sync request that might be pending
 891         * will be blocked by nr_pending, and we need to wait for
 892         * pending IO requests to complete or be queued for re-try.
 893         * Thus the number queued (nr_queued) plus this request (1)
 894         * must match the number of pending IOs (nr_pending) before
 895         * we continue.
 896         */
 897        spin_lock_irq(&conf->resync_lock);
 898        conf->barrier++;
 899        conf->nr_waiting++;
 900        wait_event_lock_irq_cmd(conf->wait_barrier,
 901                                conf->nr_pending == conf->nr_queued+1,
 902                                conf->resync_lock,
 903                                flush_pending_writes(conf));
 904        spin_unlock_irq(&conf->resync_lock);
 905}
 906static void unfreeze_array(struct r1conf *conf)
 907{
 908        /* reverse the effect of the freeze */
 909        spin_lock_irq(&conf->resync_lock);
 910        conf->barrier--;
 911        conf->nr_waiting--;
 912        wake_up(&conf->wait_barrier);
 913        spin_unlock_irq(&conf->resync_lock);
 914}
 915
 916
 917/* duplicate the data pages for behind I/O 
 918 */
 919static void alloc_behind_pages(struct bio *bio, struct r1bio *r1_bio)
 920{
 921        int i;
 922        struct bio_vec *bvec;
 923        struct bio_vec *bvecs = kzalloc(bio->bi_vcnt * sizeof(struct bio_vec),
 924                                        GFP_NOIO);
 925        if (unlikely(!bvecs))
 926                return;
 927
 928        bio_for_each_segment(bvec, bio, i) {
 929                bvecs[i] = *bvec;
 930                bvecs[i].bv_page = alloc_page(GFP_NOIO);
 931                if (unlikely(!bvecs[i].bv_page))
 932                        goto do_sync_io;
 933                memcpy(kmap(bvecs[i].bv_page) + bvec->bv_offset,
 934                       kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
 935                kunmap(bvecs[i].bv_page);
 936                kunmap(bvec->bv_page);
 937        }
 938        r1_bio->behind_bvecs = bvecs;
 939        r1_bio->behind_page_count = bio->bi_vcnt;
 940        set_bit(R1BIO_BehindIO, &r1_bio->state);
 941        return;
 942
 943do_sync_io:
 944        for (i = 0; i < bio->bi_vcnt; i++)
 945                if (bvecs[i].bv_page)
 946                        put_page(bvecs[i].bv_page);
 947        kfree(bvecs);
 948        pr_debug("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
 949}
 950
 951struct raid1_plug_cb {
 952        struct blk_plug_cb      cb;
 953        struct bio_list         pending;
 954        int                     pending_cnt;
 955};
 956
 957static void raid1_unplug(struct blk_plug_cb *cb, bool from_schedule)
 958{
 959        struct raid1_plug_cb *plug = container_of(cb, struct raid1_plug_cb,
 960                                                  cb);
 961        struct mddev *mddev = plug->cb.data;
 962        struct r1conf *conf = mddev->private;
 963        struct bio *bio;
 964
 965        if (from_schedule || current->bio_list) {
 966                spin_lock_irq(&conf->device_lock);
 967                bio_list_merge(&conf->pending_bio_list, &plug->pending);
 968                conf->pending_count += plug->pending_cnt;
 969                spin_unlock_irq(&conf->device_lock);
 970                wake_up(&conf->wait_barrier);
 971                md_wakeup_thread(mddev->thread);
 972                kfree(plug);
 973                return;
 974        }
 975
 976        /* we aren't scheduling, so we can do the write-out directly. */
 977        bio = bio_list_get(&plug->pending);
 978        bitmap_unplug(mddev->bitmap);
 979        wake_up(&conf->wait_barrier);
 980
 981        while (bio) { /* submit pending writes */
 982                struct bio *next = bio->bi_next;
 983                bio->bi_next = NULL;
 984                generic_make_request(bio);
 985                bio = next;
 986        }
 987        kfree(plug);
 988}
 989
 990static void make_request(struct mddev *mddev, struct bio * bio)
 991{
 992        struct r1conf *conf = mddev->private;
 993        struct raid1_info *mirror;
 994        struct r1bio *r1_bio;
 995        struct bio *read_bio;
 996        int i, disks;
 997        struct bitmap *bitmap;
 998        unsigned long flags;
 999        const int rw = bio_data_dir(bio);
1000        const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
1001        const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
1002        const unsigned long do_discard = (bio->bi_rw
1003                                          & (REQ_DISCARD | REQ_SECURE));
1004        const unsigned long do_same = (bio->bi_rw & REQ_WRITE_SAME);
1005        struct md_rdev *blocked_rdev;
1006        struct blk_plug_cb *cb;
1007        struct raid1_plug_cb *plug = NULL;
1008        int first_clone;
1009        int sectors_handled;
1010        int max_sectors;
1011
1012        /*
1013         * Register the new request and wait if the reconstruction
1014         * thread has put up a bar for new requests.
1015         * Continue immediately if no resync is active currently.
1016         */
1017
1018        md_write_start(mddev, bio); /* wait on superblock update early */
1019
1020        if (bio_data_dir(bio) == WRITE &&
1021            bio->bi_sector + bio->bi_size/512 > mddev->suspend_lo &&
1022            bio->bi_sector < mddev->suspend_hi) {
1023                /* As the suspend_* range is controlled by
1024                 * userspace, we want an interruptible
1025                 * wait.
1026                 */
1027                DEFINE_WAIT(w);
1028                for (;;) {
1029                        flush_signals(current);
1030                        prepare_to_wait(&conf->wait_barrier,
1031                                        &w, TASK_INTERRUPTIBLE);
1032                        if (bio->bi_sector + bio->bi_size/512 <= mddev->suspend_lo ||
1033                            bio->bi_sector >= mddev->suspend_hi)
1034                                break;
1035                        schedule();
1036                }
1037                finish_wait(&conf->wait_barrier, &w);
1038        }
1039
1040        wait_barrier(conf);
1041
1042        bitmap = mddev->bitmap;
1043
1044        /*
1045         * make_request() can abort the operation when READA is being
1046         * used and no empty request is available.
1047         *
1048         */
1049        r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
1050
1051        r1_bio->master_bio = bio;
1052        r1_bio->sectors = bio->bi_size >> 9;
1053        r1_bio->state = 0;
1054        r1_bio->mddev = mddev;
1055        r1_bio->sector = bio->bi_sector;
1056
1057        /* We might need to issue multiple reads to different
1058         * devices if there are bad blocks around, so we keep
1059         * track of the number of reads in bio->bi_phys_segments.
1060         * If this is 0, there is only one r1_bio and no locking
1061         * will be needed when requests complete.  If it is
1062         * non-zero, then it is the number of not-completed requests.
1063         */
1064        bio->bi_phys_segments = 0;
1065        clear_bit(BIO_SEG_VALID, &bio->bi_flags);
1066
1067        if (rw == READ) {
1068                /*
1069                 * read balancing logic:
1070                 */
1071                int rdisk;
1072
1073read_again:
1074                rdisk = read_balance(conf, r1_bio, &max_sectors);
1075
1076                if (rdisk < 0) {
1077                        /* couldn't find anywhere to read from */
1078                        raid_end_bio_io(r1_bio);
1079                        return;
1080                }
1081                mirror = conf->mirrors + rdisk;
1082
1083                if (test_bit(WriteMostly, &mirror->rdev->flags) &&
1084                    bitmap) {
1085                        /* Reading from a write-mostly device must
1086                         * take care not to over-take any writes
1087                         * that are 'behind'
1088                         */
1089                        wait_event(bitmap->behind_wait,
1090                                   atomic_read(&bitmap->behind_writes) == 0);
1091                }
1092                r1_bio->read_disk = rdisk;
1093
1094                read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1095                md_trim_bio(read_bio, r1_bio->sector - bio->bi_sector,
1096                            max_sectors);
1097
1098                r1_bio->bios[rdisk] = read_bio;
1099
1100                read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
1101                read_bio->bi_bdev = mirror->rdev->bdev;
1102                read_bio->bi_end_io = raid1_end_read_request;
1103                read_bio->bi_rw = READ | do_sync;
1104                read_bio->bi_private = r1_bio;
1105
1106                if (max_sectors < r1_bio->sectors) {
1107                        /* could not read all from this device, so we will
1108                         * need another r1_bio.
1109                         */
1110
1111                        sectors_handled = (r1_bio->sector + max_sectors
1112                                           - bio->bi_sector);
1113                        r1_bio->sectors = max_sectors;
1114                        spin_lock_irq(&conf->device_lock);
1115                        if (bio->bi_phys_segments == 0)
1116                                bio->bi_phys_segments = 2;
1117                        else
1118                                bio->bi_phys_segments++;
1119                        spin_unlock_irq(&conf->device_lock);
1120                        /* Cannot call generic_make_request directly
1121                         * as that will be queued in __make_request
1122                         * and subsequent mempool_alloc might block waiting
1123                         * for it.  So hand bio over to raid1d.
1124                         */
1125                        reschedule_retry(r1_bio);
1126
1127                        r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
1128
1129                        r1_bio->master_bio = bio;
1130                        r1_bio->sectors = (bio->bi_size >> 9) - sectors_handled;
1131                        r1_bio->state = 0;
1132                        r1_bio->mddev = mddev;
1133                        r1_bio->sector = bio->bi_sector + sectors_handled;
1134                        goto read_again;
1135                } else
1136                        generic_make_request(read_bio);
1137                return;
1138        }
1139
1140        /*
1141         * WRITE:
1142         */
1143        if (conf->pending_count >= max_queued_requests) {
1144                md_wakeup_thread(mddev->thread);
1145                wait_event(conf->wait_barrier,
1146                           conf->pending_count < max_queued_requests);
1147        }
1148        /* first select target devices under rcu_lock and
1149         * inc refcount on their rdev.  Record them by setting
1150         * bios[x] to bio
1151         * If there are known/acknowledged bad blocks on any device on
1152         * which we have seen a write error, we want to avoid writing those
1153         * blocks.
1154         * This potentially requires several writes to write around
1155         * the bad blocks.  Each set of writes gets it's own r1bio
1156         * with a set of bios attached.
1157         */
1158
1159        disks = conf->raid_disks * 2;
1160 retry_write:
1161        blocked_rdev = NULL;
1162        rcu_read_lock();
1163        max_sectors = r1_bio->sectors;
1164        for (i = 0;  i < disks; i++) {
1165                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
1166                if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
1167                        atomic_inc(&rdev->nr_pending);
1168                        blocked_rdev = rdev;
1169                        break;
1170                }
1171                r1_bio->bios[i] = NULL;
1172                if (!rdev || test_bit(Faulty, &rdev->flags)
1173                    || test_bit(Unmerged, &rdev->flags)) {
1174                        if (i < conf->raid_disks)
1175                                set_bit(R1BIO_Degraded, &r1_bio->state);
1176                        continue;
1177                }
1178
1179                atomic_inc(&rdev->nr_pending);
1180                if (test_bit(WriteErrorSeen, &rdev->flags)) {
1181                        sector_t first_bad;
1182                        int bad_sectors;
1183                        int is_bad;
1184
1185                        is_bad = is_badblock(rdev, r1_bio->sector,
1186                                             max_sectors,
1187                                             &first_bad, &bad_sectors);
1188                        if (is_bad < 0) {
1189                                /* mustn't write here until the bad block is
1190                                 * acknowledged*/
1191                                set_bit(BlockedBadBlocks, &rdev->flags);
1192                                blocked_rdev = rdev;
1193                                break;
1194                        }
1195                        if (is_bad && first_bad <= r1_bio->sector) {
1196                                /* Cannot write here at all */
1197                                bad_sectors -= (r1_bio->sector - first_bad);
1198                                if (bad_sectors < max_sectors)
1199                                        /* mustn't write more than bad_sectors
1200                                         * to other devices yet
1201                                         */
1202                                        max_sectors = bad_sectors;
1203                                rdev_dec_pending(rdev, mddev);
1204                                /* We don't set R1BIO_Degraded as that
1205                                 * only applies if the disk is
1206                                 * missing, so it might be re-added,
1207                                 * and we want to know to recover this
1208                                 * chunk.
1209                                 * In this case the device is here,
1210                                 * and the fact that this chunk is not
1211                                 * in-sync is recorded in the bad
1212                                 * block log
1213                                 */
1214                                continue;
1215                        }
1216                        if (is_bad) {
1217                                int good_sectors = first_bad - r1_bio->sector;
1218                                if (good_sectors < max_sectors)
1219                                        max_sectors = good_sectors;
1220                        }
1221                }
1222                r1_bio->bios[i] = bio;
1223        }
1224        rcu_read_unlock();
1225
1226        if (unlikely(blocked_rdev)) {
1227                /* Wait for this device to become unblocked */
1228                int j;
1229
1230                for (j = 0; j < i; j++)
1231                        if (r1_bio->bios[j])
1232                                rdev_dec_pending(conf->mirrors[j].rdev, mddev);
1233                r1_bio->state = 0;
1234                allow_barrier(conf);
1235                md_wait_for_blocked_rdev(blocked_rdev, mddev);
1236                wait_barrier(conf);
1237                goto retry_write;
1238        }
1239
1240        if (max_sectors < r1_bio->sectors) {
1241                /* We are splitting this write into multiple parts, so
1242                 * we need to prepare for allocating another r1_bio.
1243                 */
1244                r1_bio->sectors = max_sectors;
1245                spin_lock_irq(&conf->device_lock);
1246                if (bio->bi_phys_segments == 0)
1247                        bio->bi_phys_segments = 2;
1248                else
1249                        bio->bi_phys_segments++;
1250                spin_unlock_irq(&conf->device_lock);
1251        }
1252        sectors_handled = r1_bio->sector + max_sectors - bio->bi_sector;
1253
1254        atomic_set(&r1_bio->remaining, 1);
1255        atomic_set(&r1_bio->behind_remaining, 0);
1256
1257        first_clone = 1;
1258        for (i = 0; i < disks; i++) {
1259                struct bio *mbio;
1260                if (!r1_bio->bios[i])
1261                        continue;
1262
1263                mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
1264                md_trim_bio(mbio, r1_bio->sector - bio->bi_sector, max_sectors);
1265
1266                if (first_clone) {
1267                        /* do behind I/O ?
1268                         * Not if there are too many, or cannot
1269                         * allocate memory, or a reader on WriteMostly
1270                         * is waiting for behind writes to flush */
1271                        if (bitmap &&
1272                            (atomic_read(&bitmap->behind_writes)
1273                             < mddev->bitmap_info.max_write_behind) &&
1274                            !waitqueue_active(&bitmap->behind_wait))
1275                                alloc_behind_pages(mbio, r1_bio);
1276
1277                        bitmap_startwrite(bitmap, r1_bio->sector,
1278                                          r1_bio->sectors,
1279                                          test_bit(R1BIO_BehindIO,
1280                                                   &r1_bio->state));
1281                        first_clone = 0;
1282                }
1283                if (r1_bio->behind_bvecs) {
1284                        struct bio_vec *bvec;
1285                        int j;
1286
1287                        /* Yes, I really want the '__' version so that
1288                         * we clear any unused pointer in the io_vec, rather
1289                         * than leave them unchanged.  This is important
1290                         * because when we come to free the pages, we won't
1291                         * know the original bi_idx, so we just free
1292                         * them all
1293                         */
1294                        __bio_for_each_segment(bvec, mbio, j, 0)
1295                                bvec->bv_page = r1_bio->behind_bvecs[j].bv_page;
1296                        if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
1297                                atomic_inc(&r1_bio->behind_remaining);
1298                }
1299
1300                r1_bio->bios[i] = mbio;
1301
1302                mbio->bi_sector = (r1_bio->sector +
1303                                   conf->mirrors[i].rdev->data_offset);
1304                mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
1305                mbio->bi_end_io = raid1_end_write_request;
1306                mbio->bi_rw =
1307                        WRITE | do_flush_fua | do_sync | do_discard | do_same;
1308                mbio->bi_private = r1_bio;
1309
1310                atomic_inc(&r1_bio->remaining);
1311
1312                cb = blk_check_plugged(raid1_unplug, mddev, sizeof(*plug));
1313                if (cb)
1314                        plug = container_of(cb, struct raid1_plug_cb, cb);
1315                else
1316                        plug = NULL;
1317                spin_lock_irqsave(&conf->device_lock, flags);
1318                if (plug) {
1319                        bio_list_add(&plug->pending, mbio);
1320                        plug->pending_cnt++;
1321                } else {
1322                        bio_list_add(&conf->pending_bio_list, mbio);
1323                        conf->pending_count++;
1324                }
1325                spin_unlock_irqrestore(&conf->device_lock, flags);
1326                if (!plug)
1327                        md_wakeup_thread(mddev->thread);
1328        }
1329        /* Mustn't call r1_bio_write_done before this next test,
1330         * as it could result in the bio being freed.
1331         */
1332        if (sectors_handled < (bio->bi_size >> 9)) {
1333                r1_bio_write_done(r1_bio);
1334                /* We need another r1_bio.  It has already been counted
1335                 * in bio->bi_phys_segments
1336                 */
1337                r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
1338                r1_bio->master_bio = bio;
1339                r1_bio->sectors = (bio->bi_size >> 9) - sectors_handled;
1340                r1_bio->state = 0;
1341                r1_bio->mddev = mddev;
1342                r1_bio->sector = bio->bi_sector + sectors_handled;
1343                goto retry_write;
1344        }
1345
1346        r1_bio_write_done(r1_bio);
1347
1348        /* In case raid1d snuck in to freeze_array */
1349        wake_up(&conf->wait_barrier);
1350}
1351
1352static void status(struct seq_file *seq, struct mddev *mddev)
1353{
1354        struct r1conf *conf = mddev->private;
1355        int i;
1356
1357        seq_printf(seq, " [%d/%d] [", conf->raid_disks,
1358                   conf->raid_disks - mddev->degraded);
1359        rcu_read_lock();
1360        for (i = 0; i < conf->raid_disks; i++) {
1361                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
1362                seq_printf(seq, "%s",
1363                           rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
1364        }
1365        rcu_read_unlock();
1366        seq_printf(seq, "]");
1367}
1368
1369
1370static void error(struct mddev *mddev, struct md_rdev *rdev)
1371{
1372        char b[BDEVNAME_SIZE];
1373        struct r1conf *conf = mddev->private;
1374
1375        /*
1376         * If it is not operational, then we have already marked it as dead
1377         * else if it is the last working disks, ignore the error, let the
1378         * next level up know.
1379         * else mark the drive as failed
1380         */
1381        if (test_bit(In_sync, &rdev->flags)
1382            && (conf->raid_disks - mddev->degraded) == 1) {
1383                /*
1384                 * Don't fail the drive, act as though we were just a
1385                 * normal single drive.
1386                 * However don't try a recovery from this drive as
1387                 * it is very likely to fail.
1388                 */
1389                conf->recovery_disabled = mddev->recovery_disabled;
1390                return;
1391        }
1392        set_bit(Blocked, &rdev->flags);
1393        if (test_and_clear_bit(In_sync, &rdev->flags)) {
1394                unsigned long flags;
1395                spin_lock_irqsave(&conf->device_lock, flags);
1396                mddev->degraded++;
1397                set_bit(Faulty, &rdev->flags);
1398                spin_unlock_irqrestore(&conf->device_lock, flags);
1399                /*
1400                 * if recovery is running, make sure it aborts.
1401                 */
1402                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1403        } else
1404                set_bit(Faulty, &rdev->flags);
1405        set_bit(MD_CHANGE_DEVS, &mddev->flags);
1406        printk(KERN_ALERT
1407               "md/raid1:%s: Disk failure on %s, disabling device.\n"
1408               "md/raid1:%s: Operation continuing on %d devices.\n",
1409               mdname(mddev), bdevname(rdev->bdev, b),
1410               mdname(mddev), conf->raid_disks - mddev->degraded);
1411}
1412
1413static void print_conf(struct r1conf *conf)
1414{
1415        int i;
1416
1417        printk(KERN_DEBUG "RAID1 conf printout:\n");
1418        if (!conf) {
1419                printk(KERN_DEBUG "(!conf)\n");
1420                return;
1421        }
1422        printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1423                conf->raid_disks);
1424
1425        rcu_read_lock();
1426        for (i = 0; i < conf->raid_disks; i++) {
1427                char b[BDEVNAME_SIZE];
1428                struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
1429                if (rdev)
1430                        printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1431                               i, !test_bit(In_sync, &rdev->flags),
1432                               !test_bit(Faulty, &rdev->flags),
1433                               bdevname(rdev->bdev,b));
1434        }
1435        rcu_read_unlock();
1436}
1437
1438static void close_sync(struct r1conf *conf)
1439{
1440        wait_barrier(conf);
1441        allow_barrier(conf);
1442
1443        mempool_destroy(conf->r1buf_pool);
1444        conf->r1buf_pool = NULL;
1445}
1446
1447static int raid1_spare_active(struct mddev *mddev)
1448{
1449        int i;
1450        struct r1conf *conf = mddev->private;
1451        int count = 0;
1452        unsigned long flags;
1453
1454        /*
1455         * Find all failed disks within the RAID1 configuration 
1456         * and mark them readable.
1457         * Called under mddev lock, so rcu protection not needed.
1458         */
1459        for (i = 0; i < conf->raid_disks; i++) {
1460                struct md_rdev *rdev = conf->mirrors[i].rdev;
1461                struct md_rdev *repl = conf->mirrors[conf->raid_disks + i].rdev;
1462                if (repl
1463                    && repl->recovery_offset == MaxSector
1464                    && !test_bit(Faulty, &repl->flags)
1465                    && !test_and_set_bit(In_sync, &repl->flags)) {
1466                        /* replacement has just become active */
1467                        if (!rdev ||
1468                            !test_and_clear_bit(In_sync, &rdev->flags))
1469                                count++;
1470                        if (rdev) {
1471                                /* Replaced device not technically
1472                                 * faulty, but we need to be sure
1473                                 * it gets removed and never re-added
1474                                 */
1475                                set_bit(Faulty, &rdev->flags);
1476                                sysfs_notify_dirent_safe(
1477                                        rdev->sysfs_state);
1478                        }
1479                }
1480                if (rdev
1481                    && !test_bit(Faulty, &rdev->flags)
1482                    && !test_and_set_bit(In_sync, &rdev->flags)) {
1483                        count++;
1484                        sysfs_notify_dirent_safe(rdev->sysfs_state);
1485                }
1486        }
1487        spin_lock_irqsave(&conf->device_lock, flags);
1488        mddev->degraded -= count;
1489        spin_unlock_irqrestore(&conf->device_lock, flags);
1490
1491        print_conf(conf);
1492        return count;
1493}
1494
1495
1496static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
1497{
1498        struct r1conf *conf = mddev->private;
1499        int err = -EEXIST;
1500        int mirror = 0;
1501        struct raid1_info *p;
1502        int first = 0;
1503        int last = conf->raid_disks - 1;
1504        struct request_queue *q = bdev_get_queue(rdev->bdev);
1505
1506        if (mddev->recovery_disabled == conf->recovery_disabled)
1507                return -EBUSY;
1508
1509        if (rdev->raid_disk >= 0)
1510                first = last = rdev->raid_disk;
1511
1512        if (q->merge_bvec_fn) {
1513                set_bit(Unmerged, &rdev->flags);
1514                mddev->merge_check_needed = 1;
1515        }
1516
1517        for (mirror = first; mirror <= last; mirror++) {
1518                p = conf->mirrors+mirror;
1519                if (!p->rdev) {
1520
1521                        disk_stack_limits(mddev->gendisk, rdev->bdev,
1522                                          rdev->data_offset << 9);
1523
1524                        p->head_position = 0;
1525                        rdev->raid_disk = mirror;
1526                        err = 0;
1527                        /* As all devices are equivalent, we don't need a full recovery
1528                         * if this was recently any drive of the array
1529                         */
1530                        if (rdev->saved_raid_disk < 0)
1531                                conf->fullsync = 1;
1532                        rcu_assign_pointer(p->rdev, rdev);
1533                        break;
1534                }
1535                if (test_bit(WantReplacement, &p->rdev->flags) &&
1536                    p[conf->raid_disks].rdev == NULL) {
1537                        /* Add this device as a replacement */
1538                        clear_bit(In_sync, &rdev->flags);
1539                        set_bit(Replacement, &rdev->flags);
1540                        rdev->raid_disk = mirror;
1541                        err = 0;
1542                        conf->fullsync = 1;
1543                        rcu_assign_pointer(p[conf->raid_disks].rdev, rdev);
1544                        break;
1545                }
1546        }
1547        if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
1548                /* Some requests might not have seen this new
1549                 * merge_bvec_fn.  We must wait for them to complete
1550                 * before merging the device fully.
1551                 * First we make sure any code which has tested
1552                 * our function has submitted the request, then
1553                 * we wait for all outstanding requests to complete.
1554                 */
1555                synchronize_sched();
1556                raise_barrier(conf);
1557                lower_barrier(conf);
1558                clear_bit(Unmerged, &rdev->flags);
1559        }
1560        md_integrity_add_rdev(rdev, mddev);
1561        if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
1562                queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
1563        print_conf(conf);
1564        return err;
1565}
1566
1567static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
1568{
1569        struct r1conf *conf = mddev->private;
1570        int err = 0;
1571        int number = rdev->raid_disk;
1572        struct raid1_info *p = conf->mirrors + number;
1573
1574        if (rdev != p->rdev)
1575                p = conf->mirrors + conf->raid_disks + number;
1576
1577        print_conf(conf);
1578        if (rdev == p->rdev) {
1579                if (test_bit(In_sync, &rdev->flags) ||
1580                    atomic_read(&rdev->nr_pending)) {
1581                        err = -EBUSY;
1582                        goto abort;
1583                }
1584                /* Only remove non-faulty devices if recovery
1585                 * is not possible.
1586                 */
1587                if (!test_bit(Faulty, &rdev->flags) &&
1588                    mddev->recovery_disabled != conf->recovery_disabled &&
1589                    mddev->degraded < conf->raid_disks) {
1590                        err = -EBUSY;
1591                        goto abort;
1592                }
1593                p->rdev = NULL;
1594                synchronize_rcu();
1595                if (atomic_read(&rdev->nr_pending)) {
1596                        /* lost the race, try later */
1597                        err = -EBUSY;
1598                        p->rdev = rdev;
1599                        goto abort;
1600                } else if (conf->mirrors[conf->raid_disks + number].rdev) {
1601                        /* We just removed a device that is being replaced.
1602                         * Move down the replacement.  We drain all IO before
1603                         * doing this to avoid confusion.
1604                         */
1605                        struct md_rdev *repl =
1606                                conf->mirrors[conf->raid_disks + number].rdev;
1607                        raise_barrier(conf);
1608                        clear_bit(Replacement, &repl->flags);
1609                        p->rdev = repl;
1610                        conf->mirrors[conf->raid_disks + number].rdev = NULL;
1611                        lower_barrier(conf);
1612                        clear_bit(WantReplacement, &rdev->flags);
1613                } else
1614                        clear_bit(WantReplacement, &rdev->flags);
1615                err = md_integrity_register(mddev);
1616        }
1617abort:
1618
1619        print_conf(conf);
1620        return err;
1621}
1622
1623
1624static void end_sync_read(struct bio *bio, int error)
1625{
1626        struct r1bio *r1_bio = bio->bi_private;
1627
1628        update_head_pos(r1_bio->read_disk, r1_bio);
1629
1630        /*
1631         * we have read a block, now it needs to be re-written,
1632         * or re-read if the read failed.
1633         * We don't do much here, just schedule handling by raid1d
1634         */
1635        if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1636                set_bit(R1BIO_Uptodate, &r1_bio->state);
1637
1638        if (atomic_dec_and_test(&r1_bio->remaining))
1639                reschedule_retry(r1_bio);
1640}
1641
1642static void end_sync_write(struct bio *bio, int error)
1643{
1644        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1645        struct r1bio *r1_bio = bio->bi_private;
1646        struct mddev *mddev = r1_bio->mddev;
1647        struct r1conf *conf = mddev->private;
1648        int mirror=0;
1649        sector_t first_bad;
1650        int bad_sectors;
1651
1652        mirror = find_bio_disk(r1_bio, bio);
1653
1654        if (!uptodate) {
1655                sector_t sync_blocks = 0;
1656                sector_t s = r1_bio->sector;
1657                long sectors_to_go = r1_bio->sectors;
1658                /* make sure these bits doesn't get cleared. */
1659                do {
1660                        bitmap_end_sync(mddev->bitmap, s,
1661                                        &sync_blocks, 1);
1662                        s += sync_blocks;
1663                        sectors_to_go -= sync_blocks;
1664                } while (sectors_to_go > 0);
1665                set_bit(WriteErrorSeen,
1666                        &conf->mirrors[mirror].rdev->flags);
1667                if (!test_and_set_bit(WantReplacement,
1668                                      &conf->mirrors[mirror].rdev->flags))
1669                        set_bit(MD_RECOVERY_NEEDED, &
1670                                mddev->recovery);
1671                set_bit(R1BIO_WriteError, &r1_bio->state);
1672        } else if (is_badblock(conf->mirrors[mirror].rdev,
1673                               r1_bio->sector,
1674                               r1_bio->sectors,
1675                               &first_bad, &bad_sectors) &&
1676                   !is_badblock(conf->mirrors[r1_bio->read_disk].rdev,
1677                                r1_bio->sector,
1678                                r1_bio->sectors,
1679                                &first_bad, &bad_sectors)
1680                )
1681                set_bit(R1BIO_MadeGood, &r1_bio->state);
1682
1683        if (atomic_dec_and_test(&r1_bio->remaining)) {
1684                int s = r1_bio->sectors;
1685                if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
1686                    test_bit(R1BIO_WriteError, &r1_bio->state))
1687                        reschedule_retry(r1_bio);
1688                else {
1689                        put_buf(r1_bio);
1690                        md_done_sync(mddev, s, uptodate);
1691                }
1692        }
1693}
1694
1695static int r1_sync_page_io(struct md_rdev *rdev, sector_t sector,
1696                            int sectors, struct page *page, int rw)
1697{
1698        if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
1699                /* success */
1700                return 1;
1701        if (rw == WRITE) {
1702                set_bit(WriteErrorSeen, &rdev->flags);
1703                if (!test_and_set_bit(WantReplacement,
1704                                      &rdev->flags))
1705                        set_bit(MD_RECOVERY_NEEDED, &
1706                                rdev->mddev->recovery);
1707        }
1708        /* need to record an error - either for the block or the device */
1709        if (!rdev_set_badblocks(rdev, sector, sectors, 0))
1710                md_error(rdev->mddev, rdev);
1711        return 0;
1712}
1713
1714static int fix_sync_read_error(struct r1bio *r1_bio)
1715{
1716        /* Try some synchronous reads of other devices to get
1717         * good data, much like with normal read errors.  Only
1718         * read into the pages we already have so we don't
1719         * need to re-issue the read request.
1720         * We don't need to freeze the array, because being in an
1721         * active sync request, there is no normal IO, and
1722         * no overlapping syncs.
1723         * We don't need to check is_badblock() again as we
1724         * made sure that anything with a bad block in range
1725         * will have bi_end_io clear.
1726         */
1727        struct mddev *mddev = r1_bio->mddev;
1728        struct r1conf *conf = mddev->private;
1729        struct bio *bio = r1_bio->bios[r1_bio->read_disk];
1730        sector_t sect = r1_bio->sector;
1731        int sectors = r1_bio->sectors;
1732        int idx = 0;
1733
1734        while(sectors) {
1735                int s = sectors;
1736                int d = r1_bio->read_disk;
1737                int success = 0;
1738                struct md_rdev *rdev;
1739                int start;
1740
1741                if (s > (PAGE_SIZE>>9))
1742                        s = PAGE_SIZE >> 9;
1743                do {
1744                        if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
1745                                /* No rcu protection needed here devices
1746                                 * can only be removed when no resync is
1747                                 * active, and resync is currently active
1748                                 */
1749                                rdev = conf->mirrors[d].rdev;
1750                                if (sync_page_io(rdev, sect, s<<9,
1751                                                 bio->bi_io_vec[idx].bv_page,
1752                                                 READ, false)) {
1753                                        success = 1;
1754                                        break;
1755                                }
1756                        }
1757                        d++;
1758                        if (d == conf->raid_disks * 2)
1759                                d = 0;
1760                } while (!success && d != r1_bio->read_disk);
1761
1762                if (!success) {
1763                        char b[BDEVNAME_SIZE];
1764                        int abort = 0;
1765                        /* Cannot read from anywhere, this block is lost.
1766                         * Record a bad block on each device.  If that doesn't
1767                         * work just disable and interrupt the recovery.
1768                         * Don't fail devices as that won't really help.
1769                         */
1770                        printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O read error"
1771                               " for block %llu\n",
1772                               mdname(mddev),
1773                               bdevname(bio->bi_bdev, b),
1774                               (unsigned long long)r1_bio->sector);
1775                        for (d = 0; d < conf->raid_disks * 2; d++) {
1776                                rdev = conf->mirrors[d].rdev;
1777                                if (!rdev || test_bit(Faulty, &rdev->flags))
1778                                        continue;
1779                                if (!rdev_set_badblocks(rdev, sect, s, 0))
1780                                        abort = 1;
1781                        }
1782                        if (abort) {
1783                                conf->recovery_disabled =
1784                                        mddev->recovery_disabled;
1785                                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1786                                md_done_sync(mddev, r1_bio->sectors, 0);
1787                                put_buf(r1_bio);
1788                                return 0;
1789                        }
1790                        /* Try next page */
1791                        sectors -= s;
1792                        sect += s;
1793                        idx++;
1794                        continue;
1795                }
1796
1797                start = d;
1798                /* write it back and re-read */
1799                while (d != r1_bio->read_disk) {
1800                        if (d == 0)
1801                                d = conf->raid_disks * 2;
1802                        d--;
1803                        if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1804                                continue;
1805                        rdev = conf->mirrors[d].rdev;
1806                        if (r1_sync_page_io(rdev, sect, s,
1807                                            bio->bi_io_vec[idx].bv_page,
1808                                            WRITE) == 0) {
1809                                r1_bio->bios[d]->bi_end_io = NULL;
1810                                rdev_dec_pending(rdev, mddev);
1811                        }
1812                }
1813                d = start;
1814                while (d != r1_bio->read_disk) {
1815                        if (d == 0)
1816                                d = conf->raid_disks * 2;
1817                        d--;
1818                        if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1819                                continue;
1820                        rdev = conf->mirrors[d].rdev;
1821                        if (r1_sync_page_io(rdev, sect, s,
1822                                            bio->bi_io_vec[idx].bv_page,
1823                                            READ) != 0)
1824                                atomic_add(s, &rdev->corrected_errors);
1825                }
1826                sectors -= s;
1827                sect += s;
1828                idx ++;
1829        }
1830        set_bit(R1BIO_Uptodate, &r1_bio->state);
1831        set_bit(BIO_UPTODATE, &bio->bi_flags);
1832        return 1;
1833}
1834
1835static int process_checks(struct r1bio *r1_bio)
1836{
1837        /* We have read all readable devices.  If we haven't
1838         * got the block, then there is no hope left.
1839         * If we have, then we want to do a comparison
1840         * and skip the write if everything is the same.
1841         * If any blocks failed to read, then we need to
1842         * attempt an over-write
1843         */
1844        struct mddev *mddev = r1_bio->mddev;
1845        struct r1conf *conf = mddev->private;
1846        int primary;
1847        int i;
1848        int vcnt;
1849
1850        for (primary = 0; primary < conf->raid_disks * 2; primary++)
1851                if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
1852                    test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
1853                        r1_bio->bios[primary]->bi_end_io = NULL;
1854                        rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
1855                        break;
1856                }
1857        r1_bio->read_disk = primary;
1858        vcnt = (r1_bio->sectors + PAGE_SIZE / 512 - 1) >> (PAGE_SHIFT - 9);
1859        for (i = 0; i < conf->raid_disks * 2; i++) {
1860                int j;
1861                struct bio *pbio = r1_bio->bios[primary];
1862                struct bio *sbio = r1_bio->bios[i];
1863                int size;
1864
1865                if (r1_bio->bios[i]->bi_end_io != end_sync_read)
1866                        continue;
1867
1868                if (test_bit(BIO_UPTODATE, &sbio->bi_flags)) {
1869                        for (j = vcnt; j-- ; ) {
1870                                struct page *p, *s;
1871                                p = pbio->bi_io_vec[j].bv_page;
1872                                s = sbio->bi_io_vec[j].bv_page;
1873                                if (memcmp(page_address(p),
1874                                           page_address(s),
1875                                           sbio->bi_io_vec[j].bv_len))
1876                                        break;
1877                        }
1878                } else
1879                        j = 0;
1880                if (j >= 0)
1881                        atomic64_add(r1_bio->sectors, &mddev->resync_mismatches);
1882                if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
1883                              && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {
1884                        /* No need to write to this device. */
1885                        sbio->bi_end_io = NULL;
1886                        rdev_dec_pending(conf->mirrors[i].rdev, mddev);
1887                        continue;
1888                }
1889                /* fixup the bio for reuse */
1890                sbio->bi_vcnt = vcnt;
1891                sbio->bi_size = r1_bio->sectors << 9;
1892                sbio->bi_idx = 0;
1893                sbio->bi_phys_segments = 0;
1894                sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1895                sbio->bi_flags |= 1 << BIO_UPTODATE;
1896                sbio->bi_next = NULL;
1897                sbio->bi_sector = r1_bio->sector +
1898                        conf->mirrors[i].rdev->data_offset;
1899                sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
1900                size = sbio->bi_size;
1901                for (j = 0; j < vcnt ; j++) {
1902                        struct bio_vec *bi;
1903                        bi = &sbio->bi_io_vec[j];
1904                        bi->bv_offset = 0;
1905                        if (size > PAGE_SIZE)
1906                                bi->bv_len = PAGE_SIZE;
1907                        else
1908                                bi->bv_len = size;
1909                        size -= PAGE_SIZE;
1910                        memcpy(page_address(bi->bv_page),
1911                               page_address(pbio->bi_io_vec[j].bv_page),
1912                               PAGE_SIZE);
1913                }
1914        }
1915        return 0;
1916}
1917
1918static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
1919{
1920        struct r1conf *conf = mddev->private;
1921        int i;
1922        int disks = conf->raid_disks * 2;
1923        struct bio *bio, *wbio;
1924
1925        bio = r1_bio->bios[r1_bio->read_disk];
1926
1927        if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
1928                /* ouch - failed to read all of that. */
1929                if (!fix_sync_read_error(r1_bio))
1930                        return;
1931
1932        if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
1933                if (process_checks(r1_bio) < 0)
1934                        return;
1935        /*
1936         * schedule writes
1937         */
1938        atomic_set(&r1_bio->remaining, 1);
1939        for (i = 0; i < disks ; i++) {
1940                wbio = r1_bio->bios[i];
1941                if (wbio->bi_end_io == NULL ||
1942                    (wbio->bi_end_io == end_sync_read &&
1943                     (i == r1_bio->read_disk ||
1944                      !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
1945                        continue;
1946
1947                wbio->bi_rw = WRITE;
1948                wbio->bi_end_io = end_sync_write;
1949                atomic_inc(&r1_bio->remaining);
1950                md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
1951
1952                generic_make_request(wbio);
1953        }
1954
1955        if (atomic_dec_and_test(&r1_bio->remaining)) {
1956                /* if we're here, all write(s) have completed, so clean up */
1957                int s = r1_bio->sectors;
1958                if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
1959                    test_bit(R1BIO_WriteError, &r1_bio->state))
1960                        reschedule_retry(r1_bio);
1961                else {
1962                        put_buf(r1_bio);
1963                        md_done_sync(mddev, s, 1);
1964                }
1965        }
1966}
1967
1968/*
1969 * This is a kernel thread which:
1970 *
1971 *      1.      Retries failed read operations on working mirrors.
1972 *      2.      Updates the raid superblock when problems encounter.
1973 *      3.      Performs writes following reads for array synchronising.
1974 */
1975
1976static void fix_read_error(struct r1conf *conf, int read_disk,
1977                           sector_t sect, int sectors)
1978{
1979        struct mddev *mddev = conf->mddev;
1980        while(sectors) {
1981                int s = sectors;
1982                int d = read_disk;
1983                int success = 0;
1984                int start;
1985                struct md_rdev *rdev;
1986
1987                if (s > (PAGE_SIZE>>9))
1988                        s = PAGE_SIZE >> 9;
1989
1990                do {
1991                        /* Note: no rcu protection needed here
1992                         * as this is synchronous in the raid1d thread
1993                         * which is the thread that might remove
1994                         * a device.  If raid1d ever becomes multi-threaded....
1995                         */
1996                        sector_t first_bad;
1997                        int bad_sectors;
1998
1999                        rdev = conf->mirrors[d].rdev;
2000                        if (rdev &&
2001                            (test_bit(In_sync, &rdev->flags) ||
2002                             (!test_bit(Faulty, &rdev->flags) &&
2003                              rdev->recovery_offset >= sect + s)) &&
2004                            is_badblock(rdev, sect, s,
2005                                        &first_bad, &bad_sectors) == 0 &&
2006                            sync_page_io(rdev, sect, s<<9,
2007                                         conf->tmppage, READ, false))
2008                                success = 1;
2009                        else {
2010                                d++;
2011                                if (d == conf->raid_disks * 2)
2012                                        d = 0;
2013                        }
2014                } while (!success && d != read_disk);
2015
2016                if (!success) {
2017                        /* Cannot read from anywhere - mark it bad */
2018                        struct md_rdev *rdev = conf->mirrors[read_disk].rdev;
2019                        if (!rdev_set_badblocks(rdev, sect, s, 0))
2020                                md_error(mddev, rdev);
2021                        break;
2022                }
2023                /* write it back and re-read */
2024                start = d;
2025                while (d != read_disk) {
2026                        if (d==0)
2027                                d = conf->raid_disks * 2;
2028                        d--;
2029                        rdev = conf->mirrors[d].rdev;
2030                        if (rdev &&
2031                            test_bit(In_sync, &rdev->flags))
2032                                r1_sync_page_io(rdev, sect, s,
2033                                                conf->tmppage, WRITE);
2034                }
2035                d = start;
2036                while (d != read_disk) {
2037                        char b[BDEVNAME_SIZE];
2038                        if (d==0)
2039                                d = conf->raid_disks * 2;
2040                        d--;
2041                        rdev = conf->mirrors[d].rdev;
2042                        if (rdev &&
2043                            test_bit(In_sync, &rdev->flags)) {
2044                                if (r1_sync_page_io(rdev, sect, s,
2045                                                    conf->tmppage, READ)) {
2046                                        atomic_add(s, &rdev->corrected_errors);
2047                                        printk(KERN_INFO
2048                                               "md/raid1:%s: read error corrected "
2049                                               "(%d sectors at %llu on %s)\n",
2050                                               mdname(mddev), s,
2051                                               (unsigned long long)(sect +
2052                                                   rdev->data_offset),
2053                                               bdevname(rdev->bdev, b));
2054                                }
2055                        }
2056                }
2057                sectors -= s;
2058                sect += s;
2059        }
2060}
2061
2062static void bi_complete(struct bio *bio, int error)
2063{
2064        complete((struct completion *)bio->bi_private);
2065}
2066
2067static int submit_bio_wait(int rw, struct bio *bio)
2068{
2069        struct completion event;
2070        rw |= REQ_SYNC;
2071
2072        init_completion(&event);
2073        bio->bi_private = &event;
2074        bio->bi_end_io = bi_complete;
2075        submit_bio(rw, bio);
2076        wait_for_completion(&event);
2077
2078        return test_bit(BIO_UPTODATE, &bio->bi_flags);
2079}
2080
2081static int narrow_write_error(struct r1bio *r1_bio, int i)
2082{
2083        struct mddev *mddev = r1_bio->mddev;
2084        struct r1conf *conf = mddev->private;
2085        struct md_rdev *rdev = conf->mirrors[i].rdev;
2086        int vcnt, idx;
2087        struct bio_vec *vec;
2088
2089        /* bio has the data to be written to device 'i' where
2090         * we just recently had a write error.
2091         * We repeatedly clone the bio and trim down to one block,
2092         * then try the write.  Where the write fails we record
2093         * a bad block.
2094         * It is conceivable that the bio doesn't exactly align with
2095         * blocks.  We must handle this somehow.
2096         *
2097         * We currently own a reference on the rdev.
2098         */
2099
2100        int block_sectors;
2101        sector_t sector;
2102        int sectors;
2103        int sect_to_write = r1_bio->sectors;
2104        int ok = 1;
2105
2106        if (rdev->badblocks.shift < 0)
2107                return 0;
2108
2109        block_sectors = 1 << rdev->badblocks.shift;
2110        sector = r1_bio->sector;
2111        sectors = ((sector + block_sectors)
2112                   & ~(sector_t)(block_sectors - 1))
2113                - sector;
2114
2115        if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
2116                vcnt = r1_bio->behind_page_count;
2117                vec = r1_bio->behind_bvecs;
2118                idx = 0;
2119                while (vec[idx].bv_page == NULL)
2120                        idx++;
2121        } else {
2122                vcnt = r1_bio->master_bio->bi_vcnt;
2123                vec = r1_bio->master_bio->bi_io_vec;
2124                idx = r1_bio->master_bio->bi_idx;
2125        }
2126        while (sect_to_write) {
2127                struct bio *wbio;
2128                if (sectors > sect_to_write)
2129                        sectors = sect_to_write;
2130                /* Write at 'sector' for 'sectors'*/
2131
2132                wbio = bio_alloc_mddev(GFP_NOIO, vcnt, mddev);
2133                memcpy(wbio->bi_io_vec, vec, vcnt * sizeof(struct bio_vec));
2134                wbio->bi_sector = r1_bio->sector;
2135                wbio->bi_rw = WRITE;
2136                wbio->bi_vcnt = vcnt;
2137                wbio->bi_size = r1_bio->sectors << 9;
2138                wbio->bi_idx = idx;
2139
2140                md_trim_bio(wbio, sector - r1_bio->sector, sectors);
2141                wbio->bi_sector += rdev->data_offset;
2142                wbio->bi_bdev = rdev->bdev;
2143                if (submit_bio_wait(WRITE, wbio) == 0)
2144                        /* failure! */
2145                        ok = rdev_set_badblocks(rdev, sector,
2146                                                sectors, 0)
2147                                && ok;
2148
2149                bio_put(wbio);
2150                sect_to_write -= sectors;
2151                sector += sectors;
2152                sectors = block_sectors;
2153        }
2154        return ok;
2155}
2156
2157static void handle_sync_write_finished(struct r1conf *conf, struct r1bio *r1_bio)
2158{
2159        int m;
2160        int s = r1_bio->sectors;
2161        for (m = 0; m < conf->raid_disks * 2 ; m++) {
2162                struct md_rdev *rdev = conf->mirrors[m].rdev;
2163                struct bio *bio = r1_bio->bios[m];
2164                if (bio->bi_end_io == NULL)
2165                        continue;
2166                if (test_bit(BIO_UPTODATE, &bio->bi_flags) &&
2167                    test_bit(R1BIO_MadeGood, &r1_bio->state)) {
2168                        rdev_clear_badblocks(rdev, r1_bio->sector, s, 0);
2169                }
2170                if (!test_bit(BIO_UPTODATE, &bio->bi_flags) &&
2171                    test_bit(R1BIO_WriteError, &r1_bio->state)) {
2172                        if (!rdev_set_badblocks(rdev, r1_bio->sector, s, 0))
2173                                md_error(conf->mddev, rdev);
2174                }
2175        }
2176        put_buf(r1_bio);
2177        md_done_sync(conf->mddev, s, 1);
2178}
2179
2180static void handle_write_finished(struct r1conf *conf, struct r1bio *r1_bio)
2181{
2182        int m;
2183        for (m = 0; m < conf->raid_disks * 2 ; m++)
2184                if (r1_bio->bios[m] == IO_MADE_GOOD) {
2185                        struct md_rdev *rdev = conf->mirrors[m].rdev;
2186                        rdev_clear_badblocks(rdev,
2187                                             r1_bio->sector,
2188                                             r1_bio->sectors, 0);
2189                        rdev_dec_pending(rdev, conf->mddev);
2190                } else if (r1_bio->bios[m] != NULL) {
2191                        /* This drive got a write error.  We need to
2192                         * narrow down and record precise write
2193                         * errors.
2194                         */
2195                        if (!narrow_write_error(r1_bio, m)) {
2196                                md_error(conf->mddev,
2197                                         conf->mirrors[m].rdev);
2198                                /* an I/O failed, we can't clear the bitmap */
2199                                set_bit(R1BIO_Degraded, &r1_bio->state);
2200                        }
2201                        rdev_dec_pending(conf->mirrors[m].rdev,
2202                                         conf->mddev);
2203                }
2204        if (test_bit(R1BIO_WriteError, &r1_bio->state))
2205                close_write(r1_bio);
2206        raid_end_bio_io(r1_bio);
2207}
2208
2209static void handle_read_error(struct r1conf *conf, struct r1bio *r1_bio)
2210{
2211        int disk;
2212        int max_sectors;
2213        struct mddev *mddev = conf->mddev;
2214        struct bio *bio;
2215        char b[BDEVNAME_SIZE];
2216        struct md_rdev *rdev;
2217
2218        clear_bit(R1BIO_ReadError, &r1_bio->state);
2219        /* we got a read error. Maybe the drive is bad.  Maybe just
2220         * the block and we can fix it.
2221         * We freeze all other IO, and try reading the block from
2222         * other devices.  When we find one, we re-write
2223         * and check it that fixes the read error.
2224         * This is all done synchronously while the array is
2225         * frozen
2226         */
2227        if (mddev->ro == 0) {
2228                freeze_array(conf);
2229                fix_read_error(conf, r1_bio->read_disk,
2230                               r1_bio->sector, r1_bio->sectors);
2231                unfreeze_array(conf);
2232        } else
2233                md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
2234        rdev_dec_pending(conf->mirrors[r1_bio->read_disk].rdev, conf->mddev);
2235
2236        bio = r1_bio->bios[r1_bio->read_disk];
2237        bdevname(bio->bi_bdev, b);
2238read_more:
2239        disk = read_balance(conf, r1_bio, &max_sectors);
2240        if (disk == -1) {
2241                printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O"
2242                       " read error for block %llu\n",
2243                       mdname(mddev), b, (unsigned long long)r1_bio->sector);
2244                raid_end_bio_io(r1_bio);
2245        } else {
2246                const unsigned long do_sync
2247                        = r1_bio->master_bio->bi_rw & REQ_SYNC;
2248                if (bio) {
2249                        r1_bio->bios[r1_bio->read_disk] =
2250                                mddev->ro ? IO_BLOCKED : NULL;
2251                        bio_put(bio);
2252                }
2253                r1_bio->read_disk = disk;
2254                bio = bio_clone_mddev(r1_bio->master_bio, GFP_NOIO, mddev);
2255                md_trim_bio(bio, r1_bio->sector - bio->bi_sector, max_sectors);
2256                r1_bio->bios[r1_bio->read_disk] = bio;
2257                rdev = conf->mirrors[disk].rdev;
2258                printk_ratelimited(KERN_ERR
2259                                   "md/raid1:%s: redirecting sector %llu"
2260                                   " to other mirror: %s\n",
2261                                   mdname(mddev),
2262                                   (unsigned long long)r1_bio->sector,
2263                                   bdevname(rdev->bdev, b));
2264                bio->bi_sector = r1_bio->sector + rdev->data_offset;
2265                bio->bi_bdev = rdev->bdev;
2266                bio->bi_end_io = raid1_end_read_request;
2267                bio->bi_rw = READ | do_sync;
2268                bio->bi_private = r1_bio;
2269                if (max_sectors < r1_bio->sectors) {
2270                        /* Drat - have to split this up more */
2271                        struct bio *mbio = r1_bio->master_bio;
2272                        int sectors_handled = (r1_bio->sector + max_sectors
2273                                               - mbio->bi_sector);
2274                        r1_bio->sectors = max_sectors;
2275                        spin_lock_irq(&conf->device_lock);
2276                        if (mbio->bi_phys_segments == 0)
2277                                mbio->bi_phys_segments = 2;
2278                        else
2279                                mbio->bi_phys_segments++;
2280                        spin_unlock_irq(&conf->device_lock);
2281                        generic_make_request(bio);
2282                        bio = NULL;
2283
2284                        r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
2285
2286                        r1_bio->master_bio = mbio;
2287                        r1_bio->sectors = (mbio->bi_size >> 9)
2288                                          - sectors_handled;
2289                        r1_bio->state = 0;
2290                        set_bit(R1BIO_ReadError, &r1_bio->state);
2291                        r1_bio->mddev = mddev;
2292                        r1_bio->sector = mbio->bi_sector + sectors_handled;
2293
2294                        goto read_more;
2295                } else
2296                        generic_make_request(bio);
2297        }
2298}
2299
2300static void raid1d(struct md_thread *thread)
2301{
2302        struct mddev *mddev = thread->mddev;
2303        struct r1bio *r1_bio;
2304        unsigned long flags;
2305        struct r1conf *conf = mddev->private;
2306        struct list_head *head = &conf->retry_list;
2307        struct blk_plug plug;
2308
2309        md_check_recovery(mddev);
2310
2311        blk_start_plug(&plug);
2312        for (;;) {
2313
2314                flush_pending_writes(conf);
2315
2316                spin_lock_irqsave(&conf->device_lock, flags);
2317                if (list_empty(head)) {
2318                        spin_unlock_irqrestore(&conf->device_lock, flags);
2319                        break;
2320                }
2321                r1_bio = list_entry(head->prev, struct r1bio, retry_list);
2322                list_del(head->prev);
2323                conf->nr_queued--;
2324                spin_unlock_irqrestore(&conf->device_lock, flags);
2325
2326                mddev = r1_bio->mddev;
2327                conf = mddev->private;
2328                if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
2329                        if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
2330                            test_bit(R1BIO_WriteError, &r1_bio->state))
2331                                handle_sync_write_finished(conf, r1_bio);
2332                        else
2333                                sync_request_write(mddev, r1_bio);
2334                } else if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
2335                           test_bit(R1BIO_WriteError, &r1_bio->state))
2336                        handle_write_finished(conf, r1_bio);
2337                else if (test_bit(R1BIO_ReadError, &r1_bio->state))
2338                        handle_read_error(conf, r1_bio);
2339                else
2340                        /* just a partial read to be scheduled from separate
2341                         * context
2342                         */
2343                        generic_make_request(r1_bio->bios[r1_bio->read_disk]);
2344
2345                cond_resched();
2346                if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
2347                        md_check_recovery(mddev);
2348        }
2349        blk_finish_plug(&plug);
2350}
2351
2352
2353static int init_resync(struct r1conf *conf)
2354{
2355        int buffs;
2356
2357        buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
2358        BUG_ON(conf->r1buf_pool);
2359        conf->r1buf_pool = mempool_create(buffs, r1buf_pool_alloc, r1buf_pool_free,
2360                                          conf->poolinfo);
2361        if (!conf->r1buf_pool)
2362                return -ENOMEM;
2363        conf->next_resync = 0;
2364        return 0;
2365}
2366
2367/*
2368 * perform a "sync" on one "block"
2369 *
2370 * We need to make sure that no normal I/O request - particularly write
2371 * requests - conflict with active sync requests.
2372 *
2373 * This is achieved by tracking pending requests and a 'barrier' concept
2374 * that can be installed to exclude normal IO requests.
2375 */
2376
2377static sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
2378{
2379        struct r1conf *conf = mddev->private;
2380        struct r1bio *r1_bio;
2381        struct bio *bio;
2382        sector_t max_sector, nr_sectors;
2383        int disk = -1;
2384        int i;
2385        int wonly = -1;
2386        int write_targets = 0, read_targets = 0;
2387        sector_t sync_blocks;
2388        int still_degraded = 0;
2389        int good_sectors = RESYNC_SECTORS;
2390        int min_bad = 0; /* number of sectors that are bad in all devices */
2391
2392        if (!conf->r1buf_pool)
2393                if (init_resync(conf))
2394                        return 0;
2395
2396        max_sector = mddev->dev_sectors;
2397        if (sector_nr >= max_sector) {
2398                /* If we aborted, we need to abort the
2399                 * sync on the 'current' bitmap chunk (there will
2400                 * only be one in raid1 resync.
2401                 * We can find the current addess in mddev->curr_resync
2402                 */
2403                if (mddev->curr_resync < max_sector) /* aborted */
2404                        bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2405                                                &sync_blocks, 1);
2406                else /* completed sync */
2407                        conf->fullsync = 0;
2408
2409                bitmap_close_sync(mddev->bitmap);
2410                close_sync(conf);
2411                return 0;
2412        }
2413
2414        if (mddev->bitmap == NULL &&
2415            mddev->recovery_cp == MaxSector &&
2416            !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
2417            conf->fullsync == 0) {
2418                *skipped = 1;
2419                return max_sector - sector_nr;
2420        }
2421        /* before building a request, check if we can skip these blocks..
2422         * This call the bitmap_start_sync doesn't actually record anything
2423         */
2424        if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
2425            !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
2426                /* We can skip this block, and probably several more */
2427                *skipped = 1;
2428                return sync_blocks;
2429        }
2430        /*
2431         * If there is non-resync activity waiting for a turn,
2432         * and resync is going fast enough,
2433         * then let it though before starting on this new sync request.
2434         */
2435        if (!go_faster && conf->nr_waiting)
2436                msleep_interruptible(1000);
2437
2438        bitmap_cond_end_sync(mddev->bitmap, sector_nr);
2439        r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
2440        raise_barrier(conf);
2441
2442        conf->next_resync = sector_nr;
2443
2444        rcu_read_lock();
2445        /*
2446         * If we get a correctably read error during resync or recovery,
2447         * we might want to read from a different device.  So we
2448         * flag all drives that could conceivably be read from for READ,
2449         * and any others (which will be non-In_sync devices) for WRITE.
2450         * If a read fails, we try reading from something else for which READ
2451         * is OK.
2452         */
2453
2454        r1_bio->mddev = mddev;
2455        r1_bio->sector = sector_nr;
2456        r1_bio->state = 0;
2457        set_bit(R1BIO_IsSync, &r1_bio->state);
2458
2459        for (i = 0; i < conf->raid_disks * 2; i++) {
2460                struct md_rdev *rdev;
2461                bio = r1_bio->bios[i];
2462
2463                /* take from bio_init */
2464                bio->bi_next = NULL;
2465                bio->bi_flags &= ~(BIO_POOL_MASK-1);
2466                bio->bi_flags |= 1 << BIO_UPTODATE;
2467                bio->bi_rw = READ;
2468                bio->bi_vcnt = 0;
2469                bio->bi_idx = 0;
2470                bio->bi_phys_segments = 0;
2471                bio->bi_size = 0;
2472                bio->bi_end_io = NULL;
2473                bio->bi_private = NULL;
2474
2475                rdev = rcu_dereference(conf->mirrors[i].rdev);
2476                if (rdev == NULL ||
2477                    test_bit(Faulty, &rdev->flags)) {
2478                        if (i < conf->raid_disks)
2479                                still_degraded = 1;
2480                } else if (!test_bit(In_sync, &rdev->flags)) {
2481                        bio->bi_rw = WRITE;
2482                        bio->bi_end_io = end_sync_write;
2483                        write_targets ++;
2484                } else {
2485                        /* may need to read from here */
2486                        sector_t first_bad = MaxSector;
2487                        int bad_sectors;
2488
2489                        if (is_badblock(rdev, sector_nr, good_sectors,
2490                                        &first_bad, &bad_sectors)) {
2491                                if (first_bad > sector_nr)
2492                                        good_sectors = first_bad - sector_nr;
2493                                else {
2494                                        bad_sectors -= (sector_nr - first_bad);
2495                                        if (min_bad == 0 ||
2496                                            min_bad > bad_sectors)
2497                                                min_bad = bad_sectors;
2498                                }
2499                        }
2500                        if (sector_nr < first_bad) {
2501                                if (test_bit(WriteMostly, &rdev->flags)) {
2502                                        if (wonly < 0)
2503                                                wonly = i;
2504                                } else {
2505                                        if (disk < 0)
2506                                                disk = i;
2507                                }
2508                                bio->bi_rw = READ;
2509                                bio->bi_end_io = end_sync_read;
2510                                read_targets++;
2511                        } else if (!test_bit(WriteErrorSeen, &rdev->flags) &&
2512                                test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
2513                                !test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
2514                                /*
2515                                 * The device is suitable for reading (InSync),
2516                                 * but has bad block(s) here. Let's try to correct them,
2517                                 * if we are doing resync or repair. Otherwise, leave
2518                                 * this device alone for this sync request.
2519                                 */
2520                                bio->bi_rw = WRITE;
2521                                bio->bi_end_io = end_sync_write;
2522                                write_targets++;
2523                        }
2524                }
2525                if (bio->bi_end_io) {
2526                        atomic_inc(&rdev->nr_pending);
2527                        bio->bi_sector = sector_nr + rdev->data_offset;
2528                        bio->bi_bdev = rdev->bdev;
2529                        bio->bi_private = r1_bio;
2530                }
2531        }
2532        rcu_read_unlock();
2533        if (disk < 0)
2534                disk = wonly;
2535        r1_bio->read_disk = disk;
2536
2537        if (read_targets == 0 && min_bad > 0) {
2538                /* These sectors are bad on all InSync devices, so we
2539                 * need to mark them bad on all write targets
2540                 */
2541                int ok = 1;
2542                for (i = 0 ; i < conf->raid_disks * 2 ; i++)
2543                        if (r1_bio->bios[i]->bi_end_io == end_sync_write) {
2544                                struct md_rdev *rdev = conf->mirrors[i].rdev;
2545                                ok = rdev_set_badblocks(rdev, sector_nr,
2546                                                        min_bad, 0
2547                                        ) && ok;
2548                        }
2549                set_bit(MD_CHANGE_DEVS, &mddev->flags);
2550                *skipped = 1;
2551                put_buf(r1_bio);
2552
2553                if (!ok) {
2554                        /* Cannot record the badblocks, so need to
2555                         * abort the resync.
2556                         * If there are multiple read targets, could just
2557                         * fail the really bad ones ???
2558                         */
2559                        conf->recovery_disabled = mddev->recovery_disabled;
2560                        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2561                        return 0;
2562                } else
2563                        return min_bad;
2564
2565        }
2566        if (min_bad > 0 && min_bad < good_sectors) {
2567                /* only resync enough to reach the next bad->good
2568                 * transition */
2569                good_sectors = min_bad;
2570        }
2571
2572        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
2573                /* extra read targets are also write targets */
2574                write_targets += read_targets-1;
2575
2576        if (write_targets == 0 || read_targets == 0) {
2577                /* There is nowhere to write, so all non-sync
2578                 * drives must be failed - so we are finished
2579                 */
2580                sector_t rv;
2581                if (min_bad > 0)
2582                        max_sector = sector_nr + min_bad;
2583                rv = max_sector - sector_nr;
2584                *skipped = 1;
2585                put_buf(r1_bio);
2586                return rv;
2587        }
2588
2589        if (max_sector > mddev->resync_max)
2590                max_sector = mddev->resync_max; /* Don't do IO beyond here */
2591        if (max_sector > sector_nr + good_sectors)
2592                max_sector = sector_nr + good_sectors;
2593        nr_sectors = 0;
2594        sync_blocks = 0;
2595        do {
2596                struct page *page;
2597                int len = PAGE_SIZE;
2598                if (sector_nr + (len>>9) > max_sector)
2599                        len = (max_sector - sector_nr) << 9;
2600                if (len == 0)
2601                        break;
2602                if (sync_blocks == 0) {
2603                        if (!bitmap_start_sync(mddev->bitmap, sector_nr,
2604                                               &sync_blocks, still_degraded) &&
2605                            !conf->fullsync &&
2606                            !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
2607                                break;
2608                        BUG_ON(sync_blocks < (PAGE_SIZE>>9));
2609                        if ((len >> 9) > sync_blocks)
2610                                len = sync_blocks<<9;
2611                }
2612
2613                for (i = 0 ; i < conf->raid_disks * 2; i++) {
2614                        bio = r1_bio->bios[i];
2615                        if (bio->bi_end_io) {
2616                                page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
2617                                if (bio_add_page(bio, page, len, 0) == 0) {
2618                                        /* stop here */
2619                                        bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
2620                                        while (i > 0) {
2621                                                i--;
2622                                                bio = r1_bio->bios[i];
2623                                                if (bio->bi_end_io==NULL)
2624                                                        continue;
2625                                                /* remove last page from this bio */
2626                                                bio->bi_vcnt--;
2627                                                bio->bi_size -= len;
2628                                                bio->bi_flags &= ~(1<< BIO_SEG_VALID);
2629                                        }
2630                                        goto bio_full;
2631                                }
2632                        }
2633                }
2634                nr_sectors += len>>9;
2635                sector_nr += len>>9;
2636                sync_blocks -= (len>>9);
2637        } while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
2638 bio_full:
2639        r1_bio->sectors = nr_sectors;
2640
2641        /* For a user-requested sync, we read all readable devices and do a
2642         * compare
2643         */
2644        if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
2645                atomic_set(&r1_bio->remaining, read_targets);
2646                for (i = 0; i < conf->raid_disks * 2 && read_targets; i++) {
2647                        bio = r1_bio->bios[i];
2648                        if (bio->bi_end_io == end_sync_read) {
2649                                read_targets--;
2650                                md_sync_acct(bio->bi_bdev, nr_sectors);
2651                                generic_make_request(bio);
2652                        }
2653                }
2654        } else {
2655                atomic_set(&r1_bio->remaining, 1);
2656                bio = r1_bio->bios[r1_bio->read_disk];
2657                md_sync_acct(bio->bi_bdev, nr_sectors);
2658                generic_make_request(bio);
2659
2660        }
2661        return nr_sectors;
2662}
2663
2664static sector_t raid1_size(struct mddev *mddev, sector_t sectors, int raid_disks)
2665{
2666        if (sectors)
2667                return sectors;
2668
2669        return mddev->dev_sectors;
2670}
2671
2672static struct r1conf *setup_conf(struct mddev *mddev)
2673{
2674        struct r1conf *conf;
2675        int i;
2676        struct raid1_info *disk;
2677        struct md_rdev *rdev;
2678        int err = -ENOMEM;
2679
2680        conf = kzalloc(sizeof(struct r1conf), GFP_KERNEL);
2681        if (!conf)
2682                goto abort;
2683
2684        conf->mirrors = kzalloc(sizeof(struct raid1_info)
2685                                * mddev->raid_disks * 2,
2686                                 GFP_KERNEL);
2687        if (!conf->mirrors)
2688                goto abort;
2689
2690        conf->tmppage = alloc_page(GFP_KERNEL);
2691        if (!conf->tmppage)
2692                goto abort;
2693
2694        conf->poolinfo = kzalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
2695        if (!conf->poolinfo)
2696                goto abort;
2697        conf->poolinfo->raid_disks = mddev->raid_disks * 2;
2698        conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2699                                          r1bio_pool_free,
2700                                          conf->poolinfo);
2701        if (!conf->r1bio_pool)
2702                goto abort;
2703
2704        conf->poolinfo->mddev = mddev;
2705
2706        err = -EINVAL;
2707        spin_lock_init(&conf->device_lock);
2708        rdev_for_each(rdev, mddev) {
2709                struct request_queue *q;
2710                int disk_idx = rdev->raid_disk;
2711                if (disk_idx >= mddev->raid_disks
2712                    || disk_idx < 0)
2713                        continue;
2714                if (test_bit(Replacement, &rdev->flags))
2715                        disk = conf->mirrors + mddev->raid_disks + disk_idx;
2716                else
2717                        disk = conf->mirrors + disk_idx;
2718
2719                if (disk->rdev)
2720                        goto abort;
2721                disk->rdev = rdev;
2722                q = bdev_get_queue(rdev->bdev);
2723                if (q->merge_bvec_fn)
2724                        mddev->merge_check_needed = 1;
2725
2726                disk->head_position = 0;
2727                disk->seq_start = MaxSector;
2728        }
2729        conf->raid_disks = mddev->raid_disks;
2730        conf->mddev = mddev;
2731        INIT_LIST_HEAD(&conf->retry_list);
2732
2733        spin_lock_init(&conf->resync_lock);
2734        init_waitqueue_head(&conf->wait_barrier);
2735
2736        bio_list_init(&conf->pending_bio_list);
2737        conf->pending_count = 0;
2738        conf->recovery_disabled = mddev->recovery_disabled - 1;
2739
2740        err = -EIO;
2741        for (i = 0; i < conf->raid_disks * 2; i++) {
2742
2743                disk = conf->mirrors + i;
2744
2745                if (i < conf->raid_disks &&
2746                    disk[conf->raid_disks].rdev) {
2747                        /* This slot has a replacement. */
2748                        if (!disk->rdev) {
2749                                /* No original, just make the replacement
2750                                 * a recovering spare
2751                                 */
2752                                disk->rdev =
2753                                        disk[conf->raid_disks].rdev;
2754                                disk[conf->raid_disks].rdev = NULL;
2755                        } else if (!test_bit(In_sync, &disk->rdev->flags))
2756                                /* Original is not in_sync - bad */
2757                                goto abort;
2758                }
2759
2760                if (!disk->rdev ||
2761                    !test_bit(In_sync, &disk->rdev->flags)) {
2762                        disk->head_position = 0;
2763                        if (disk->rdev &&
2764                            (disk->rdev->saved_raid_disk < 0))
2765                                conf->fullsync = 1;
2766                }
2767        }
2768
2769        err = -ENOMEM;
2770        conf->thread = md_register_thread(raid1d, mddev, "raid1");
2771        if (!conf->thread) {
2772                printk(KERN_ERR
2773                       "md/raid1:%s: couldn't allocate thread\n",
2774                       mdname(mddev));
2775                goto abort;
2776        }
2777
2778        return conf;
2779
2780 abort:
2781        if (conf) {
2782                if (conf->r1bio_pool)
2783                        mempool_destroy(conf->r1bio_pool);
2784                kfree(conf->mirrors);
2785                safe_put_page(conf->tmppage);
2786                kfree(conf->poolinfo);
2787                kfree(conf);
2788        }
2789        return ERR_PTR(err);
2790}
2791
2792static int stop(struct mddev *mddev);
2793static int run(struct mddev *mddev)
2794{
2795        struct r1conf *conf;
2796        int i;
2797        struct md_rdev *rdev;
2798        int ret;
2799        bool discard_supported = false;
2800
2801        if (mddev->level != 1) {
2802                printk(KERN_ERR "md/raid1:%s: raid level not set to mirroring (%d)\n",
2803                       mdname(mddev), mddev->level);
2804                return -EIO;
2805        }
2806        if (mddev->reshape_position != MaxSector) {
2807                printk(KERN_ERR "md/raid1:%s: reshape_position set but not supported\n",
2808                       mdname(mddev));
2809                return -EIO;
2810        }
2811        /*
2812         * copy the already verified devices into our private RAID1
2813         * bookkeeping area. [whatever we allocate in run(),
2814         * should be freed in stop()]
2815         */
2816        if (mddev->private == NULL)
2817                conf = setup_conf(mddev);
2818        else
2819                conf = mddev->private;
2820
2821        if (IS_ERR(conf))
2822                return PTR_ERR(conf);
2823
2824        if (mddev->queue)
2825                blk_queue_max_write_same_sectors(mddev->queue,
2826                                                 mddev->chunk_sectors);
2827        rdev_for_each(rdev, mddev) {
2828                if (!mddev->gendisk)
2829                        continue;
2830                disk_stack_limits(mddev->gendisk, rdev->bdev,
2831                                  rdev->data_offset << 9);
2832                if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
2833                        discard_supported = true;
2834        }
2835
2836        mddev->degraded = 0;
2837        for (i=0; i < conf->raid_disks; i++)
2838                if (conf->mirrors[i].rdev == NULL ||
2839                    !test_bit(In_sync, &conf->mirrors[i].rdev->flags) ||
2840                    test_bit(Faulty, &conf->mirrors[i].rdev->flags))
2841                        mddev->degraded++;
2842
2843        if (conf->raid_disks - mddev->degraded == 1)
2844                mddev->recovery_cp = MaxSector;
2845
2846        if (mddev->recovery_cp != MaxSector)
2847                printk(KERN_NOTICE "md/raid1:%s: not clean"
2848                       " -- starting background reconstruction\n",
2849                       mdname(mddev));
2850        printk(KERN_INFO 
2851                "md/raid1:%s: active with %d out of %d mirrors\n",
2852                mdname(mddev), mddev->raid_disks - mddev->degraded, 
2853                mddev->raid_disks);
2854
2855        /*
2856         * Ok, everything is just fine now
2857         */
2858        mddev->thread = conf->thread;
2859        conf->thread = NULL;
2860        mddev->private = conf;
2861
2862        md_set_array_sectors(mddev, raid1_size(mddev, 0, 0));
2863
2864        if (mddev->queue) {
2865                mddev->queue->backing_dev_info.congested_fn = raid1_congested;
2866                mddev->queue->backing_dev_info.congested_data = mddev;
2867                blk_queue_merge_bvec(mddev->queue, raid1_mergeable_bvec);
2868
2869                if (discard_supported)
2870                        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
2871                                                mddev->queue);
2872                else
2873                        queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
2874                                                  mddev->queue);
2875        }
2876
2877        ret =  md_integrity_register(mddev);
2878        if (ret)
2879                stop(mddev);
2880        return ret;
2881}
2882
2883static int stop(struct mddev *mddev)
2884{
2885        struct r1conf *conf = mddev->private;
2886        struct bitmap *bitmap = mddev->bitmap;
2887
2888        /* wait for behind writes to complete */
2889        if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
2890                printk(KERN_INFO "md/raid1:%s: behind writes in progress - waiting to stop.\n",
2891                       mdname(mddev));
2892                /* need to kick something here to make sure I/O goes? */
2893                wait_event(bitmap->behind_wait,
2894                           atomic_read(&bitmap->behind_writes) == 0);
2895        }
2896
2897        raise_barrier(conf);
2898        lower_barrier(conf);
2899
2900        md_unregister_thread(&mddev->thread);
2901        if (conf->r1bio_pool)
2902                mempool_destroy(conf->r1bio_pool);
2903        kfree(conf->mirrors);
2904        kfree(conf->poolinfo);
2905        kfree(conf);
2906        mddev->private = NULL;
2907        return 0;
2908}
2909
2910static int raid1_resize(struct mddev *mddev, sector_t sectors)
2911{
2912        /* no resync is happening, and there is enough space
2913         * on all devices, so we can resize.
2914         * We need to make sure resync covers any new space.
2915         * If the array is shrinking we should possibly wait until
2916         * any io in the removed space completes, but it hardly seems
2917         * worth it.
2918         */
2919        sector_t newsize = raid1_size(mddev, sectors, 0);
2920        if (mddev->external_size &&
2921            mddev->array_sectors > newsize)
2922                return -EINVAL;
2923        if (mddev->bitmap) {
2924                int ret = bitmap_resize(mddev->bitmap, newsize, 0, 0);
2925                if (ret)
2926                        return ret;
2927        }
2928        md_set_array_sectors(mddev, newsize);
2929        set_capacity(mddev->gendisk, mddev->array_sectors);
2930        revalidate_disk(mddev->gendisk);
2931        if (sectors > mddev->dev_sectors &&
2932            mddev->recovery_cp > mddev->dev_sectors) {
2933                mddev->recovery_cp = mddev->dev_sectors;
2934                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2935        }
2936        mddev->dev_sectors = sectors;
2937        mddev->resync_max_sectors = sectors;
2938        return 0;
2939}
2940
2941static int raid1_reshape(struct mddev *mddev)
2942{
2943        /* We need to:
2944         * 1/ resize the r1bio_pool
2945         * 2/ resize conf->mirrors
2946         *
2947         * We allocate a new r1bio_pool if we can.
2948         * Then raise a device barrier and wait until all IO stops.
2949         * Then resize conf->mirrors and swap in the new r1bio pool.
2950         *
2951         * At the same time, we "pack" the devices so that all the missing
2952         * devices have the higher raid_disk numbers.
2953         */
2954        mempool_t *newpool, *oldpool;
2955        struct pool_info *newpoolinfo;
2956        struct raid1_info *newmirrors;
2957        struct r1conf *conf = mddev->private;
2958        int cnt, raid_disks;
2959        unsigned long flags;
2960        int d, d2, err;
2961
2962        /* Cannot change chunk_size, layout, or level */
2963        if (mddev->chunk_sectors != mddev->new_chunk_sectors ||
2964            mddev->layout != mddev->new_layout ||
2965            mddev->level != mddev->new_level) {
2966                mddev->new_chunk_sectors = mddev->chunk_sectors;
2967                mddev->new_layout = mddev->layout;
2968                mddev->new_level = mddev->level;
2969                return -EINVAL;
2970        }
2971
2972        err = md_allow_write(mddev);
2973        if (err)
2974                return err;
2975
2976        raid_disks = mddev->raid_disks + mddev->delta_disks;
2977
2978        if (raid_disks < conf->raid_disks) {
2979                cnt=0;
2980                for (d= 0; d < conf->raid_disks; d++)
2981                        if (conf->mirrors[d].rdev)
2982                                cnt++;
2983                if (cnt > raid_disks)
2984                        return -EBUSY;
2985        }
2986
2987        newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
2988        if (!newpoolinfo)
2989                return -ENOMEM;
2990        newpoolinfo->mddev = mddev;
2991        newpoolinfo->raid_disks = raid_disks * 2;
2992
2993        newpool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2994                                 r1bio_pool_free, newpoolinfo);
2995        if (!newpool) {
2996                kfree(newpoolinfo);
2997                return -ENOMEM;
2998        }
2999        newmirrors = kzalloc(sizeof(struct raid1_info) * raid_disks * 2,
3000                             GFP_KERNEL);
3001        if (!newmirrors) {
3002                kfree(newpoolinfo);
3003                mempool_destroy(newpool);
3004                return -ENOMEM;
3005        }
3006
3007        raise_barrier(conf);
3008
3009        /* ok, everything is stopped */
3010        oldpool = conf->r1bio_pool;
3011        conf->r1bio_pool = newpool;
3012
3013        for (d = d2 = 0; d < conf->raid_disks; d++) {
3014                struct md_rdev *rdev = conf->mirrors[d].rdev;
3015                if (rdev && rdev->raid_disk != d2) {
3016                        sysfs_unlink_rdev(mddev, rdev);
3017                        rdev->raid_disk = d2;
3018                        sysfs_unlink_rdev(mddev, rdev);
3019                        if (sysfs_link_rdev(mddev, rdev))
3020                                printk(KERN_WARNING
3021                                       "md/raid1:%s: cannot register rd%d\n",
3022                                       mdname(mddev), rdev->raid_disk);
3023                }
3024                if (rdev)
3025                        newmirrors[d2++].rdev = rdev;
3026        }
3027        kfree(conf->mirrors);
3028        conf->mirrors = newmirrors;
3029        kfree(conf->poolinfo);
3030        conf->poolinfo = newpoolinfo;
3031
3032        spin_lock_irqsave(&conf->device_lock, flags);
3033        mddev->degraded += (raid_disks - conf->raid_disks);
3034        spin_unlock_irqrestore(&conf->device_lock, flags);
3035        conf->raid_disks = mddev->raid_disks = raid_disks;
3036        mddev->delta_disks = 0;
3037
3038        lower_barrier(conf);
3039
3040        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3041        md_wakeup_thread(mddev->thread);
3042
3043        mempool_destroy(oldpool);
3044        return 0;
3045}
3046
3047static void raid1_quiesce(struct mddev *mddev, int state)
3048{
3049        struct r1conf *conf = mddev->private;
3050
3051        switch(state) {
3052        case 2: /* wake for suspend */
3053                wake_up(&conf->wait_barrier);
3054                break;
3055        case 1:
3056                raise_barrier(conf);
3057                break;
3058        case 0:
3059                lower_barrier(conf);
3060                break;
3061        }
3062}
3063
3064static void *raid1_takeover(struct mddev *mddev)
3065{
3066        /* raid1 can take over:
3067         *  raid5 with 2 devices, any layout or chunk size
3068         */
3069        if (mddev->level == 5 && mddev->raid_disks == 2) {
3070                struct r1conf *conf;
3071                mddev->new_level = 1;
3072                mddev->new_layout = 0;
3073                mddev->new_chunk_sectors = 0;
3074                conf = setup_conf(mddev);
3075                if (!IS_ERR(conf))
3076                        conf->barrier = 1;
3077                return conf;
3078        }
3079        return ERR_PTR(-EINVAL);
3080}
3081
3082static struct md_personality raid1_personality =
3083{
3084        .name           = "raid1",
3085        .level          = 1,
3086        .owner          = THIS_MODULE,
3087        .make_request   = make_request,
3088        .run            = run,
3089        .stop           = stop,
3090        .status         = status,
3091        .error_handler  = error,
3092        .hot_add_disk   = raid1_add_disk,
3093        .hot_remove_disk= raid1_remove_disk,
3094        .spare_active   = raid1_spare_active,
3095        .sync_request   = sync_request,
3096        .resize         = raid1_resize,
3097        .size           = raid1_size,
3098        .check_reshape  = raid1_reshape,
3099        .quiesce        = raid1_quiesce,
3100        .takeover       = raid1_takeover,
3101};
3102
3103static int __init raid_init(void)
3104{
3105        return register_md_personality(&raid1_personality);
3106}
3107
3108static void raid_exit(void)
3109{
3110        unregister_md_personality(&raid1_personality);
3111}
3112
3113module_init(raid_init);
3114module_exit(raid_exit);
3115MODULE_LICENSE("GPL");
3116MODULE_DESCRIPTION("RAID1 (mirroring) personality for MD");
3117MODULE_ALIAS("md-personality-3"); /* RAID1 */
3118MODULE_ALIAS("md-raid1");
3119MODULE_ALIAS("md-level-1");
3120
3121module_param(max_queued_requests, int, S_IRUGO|S_IWUSR);
3122
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