drivers/md/raid1.c

   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 Østergaard" <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/seq_file.h>
  38 #include "md.h"
  39 #include "raid1.h"
  40 #include "bitmap.h"
  41
  42 #define DEBUG 0
  43 #if DEBUG
  44 #define PRINTK(x...) printk(x)
  45 #else
  46 #define PRINTK(x...)
  47 #endif
  48
  49 /*
  50  * Number of guaranteed r1bios in case of extreme VM load:
  51  */
  52 #define NR_RAID1_BIOS 256
  53
  54
  55 static void unplug_slaves(mddev_t *mddev);
  56
  57 static void allow_barrier(conf_t *conf);
  58 static void lower_barrier(conf_t *conf);
  59
  60 static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
  61 {
  62         struct pool_info *pi = data;
  63         r1bio_t *r1_bio;
  64         int size = offsetof(r1bio_t, bios[pi->raid_disks]);
  65
  66         /* allocate a r1bio with room for raid_disks entries in the bios array */
  67         r1_bio = kzalloc(size, gfp_flags);
  68         if (!r1_bio && pi->mddev)
  69                 unplug_slaves(pi->mddev);
  70
  71         return r1_bio;
  72 }
  73
  74 static void r1bio_pool_free(void *r1_bio, void *data)
  75 {
  76         kfree(r1_bio);
  77 }
  78
  79 #define RESYNC_BLOCK_SIZE (64*1024)
  80 //#define RESYNC_BLOCK_SIZE PAGE_SIZE
  81 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
  82 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
  83 #define RESYNC_WINDOW (2048*1024)
  84
  85 static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
  86 {
  87         struct pool_info *pi = data;
  88         struct page *page;
  89         r1bio_t *r1_bio;
  90         struct bio *bio;
  91         int i, j;
  92
  93         r1_bio = r1bio_pool_alloc(gfp_flags, pi);
  94         if (!r1_bio) {
  95                 unplug_slaves(pi->mddev);
  96                 return NULL;
  97         }
  98
  99         /*
 100          * Allocate bios : 1 for reading, n-1 for writing
 101          */
 102         for (j = pi->raid_disks ; j-- ; ) {
 103                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
 104                 if (!bio)
 105                         goto out_free_bio;
 106                 r1_bio->bios[j] = bio;
 107         }
 108         /*
 109          * Allocate RESYNC_PAGES data pages and attach them to
 110          * the first bio.
 111          * If this is a user-requested check/repair, allocate
 112          * RESYNC_PAGES for each bio.
 113          */
 114         if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
 115                 j = pi->raid_disks;
 116         else
 117                 j = 1;
 118         while(j--) {
 119                 bio = r1_bio->bios[j];
 120                 for (i = 0; i < RESYNC_PAGES; i++) {
 121                         page = alloc_page(gfp_flags);
 122                         if (unlikely(!page))
 123                                 goto out_free_pages;
 124
 125                         bio->bi_io_vec[i].bv_page = page;
 126                         bio->bi_vcnt = i+1;
 127                 }
 128         }
 129         /* If not user-requests, copy the page pointers to all bios */
 130         if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
 131                 for (i=0; i<RESYNC_PAGES ; i++)
 132                         for (j=1; j<pi->raid_disks; j++)
 133                                 r1_bio->bios[j]->bi_io_vec[i].bv_page =
 134                                         r1_bio->bios[0]->bi_io_vec[i].bv_page;
 135         }
 136
 137         r1_bio->master_bio = NULL;
 138
 139         return r1_bio;
 140
 141 out_free_pages:
 142         for (j=0 ; j < pi->raid_disks; j++)
 143                 for (i=0; i < r1_bio->bios[j]->bi_vcnt ; i++)
 144                         put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
 145         j = -1;
 146 out_free_bio:
 147         while ( ++j < pi->raid_disks )
 148                 bio_put(r1_bio->bios[j]);
 149         r1bio_pool_free(r1_bio, data);
 150         return NULL;
 151 }
 152
 153 static void r1buf_pool_free(void *__r1_bio, void *data)
 154 {
 155         struct pool_info *pi = data;
 156         int i,j;
 157         r1bio_t *r1bio = __r1_bio;
 158
 159         for (i = 0; i < RESYNC_PAGES; i++)
 160                 for (j = pi->raid_disks; j-- ;) {
 161                         if (j == 0 ||
 162                             r1bio->bios[j]->bi_io_vec[i].bv_page !=
 163                             r1bio->bios[0]->bi_io_vec[i].bv_page)
 164                                 safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
 165                 }
 166         for (i=0 ; i < pi->raid_disks; i++)
 167                 bio_put(r1bio->bios[i]);
 168
 169         r1bio_pool_free(r1bio, data);
 170 }
 171
 172 static void put_all_bios(conf_t *conf, r1bio_t *r1_bio)
 173 {
 174         int i;
 175
 176         for (i = 0; i < conf->raid_disks; i++) {
 177                 struct bio **bio = r1_bio->bios + i;
 178                 if (*bio && *bio != IO_BLOCKED)
 179                         bio_put(*bio);
 180                 *bio = NULL;
 181         }
 182 }
 183
 184 static void free_r1bio(r1bio_t *r1_bio)
 185 {
 186         conf_t *conf = r1_bio->mddev->private;
 187
 188         /*
 189          * Wake up any possible resync thread that waits for the device
 190          * to go idle.
 191          */
 192         allow_barrier(conf);
 193
 194         put_all_bios(conf, r1_bio);
 195         mempool_free(r1_bio, conf->r1bio_pool);
 196 }
 197
 198 static void put_buf(r1bio_t *r1_bio)
 199 {
 200         conf_t *conf = r1_bio->mddev->private;
 201         int i;
 202
 203         for (i=0; i<conf->raid_disks; i++) {
 204                 struct bio *bio = r1_bio->bios[i];
 205                 if (bio->bi_end_io)
 206                         rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
 207         }
 208
 209         mempool_free(r1_bio, conf->r1buf_pool);
 210
 211         lower_barrier(conf);
 212 }
 213
 214 static void reschedule_retry(r1bio_t *r1_bio)
 215 {
 216         unsigned long flags;
 217         mddev_t *mddev = r1_bio->mddev;
 218         conf_t *conf = mddev->private;
 219
 220         spin_lock_irqsave(&conf->device_lock, flags);
 221         list_add(&r1_bio->retry_list, &conf->retry_list);
 222         conf->nr_queued ++;
 223         spin_unlock_irqrestore(&conf->device_lock, flags);
 224
 225         wake_up(&conf->wait_barrier);
 226         md_wakeup_thread(mddev->thread);
 227 }
 228
 229 /*
 230  * raid_end_bio_io() is called when we have finished servicing a mirrored
 231  * operation and are ready to return a success/failure code to the buffer
 232  * cache layer.
 233  */
 234 static void raid_end_bio_io(r1bio_t *r1_bio)
 235 {
 236         struct bio *bio = r1_bio->master_bio;
 237
 238         /* if nobody has done the final endio yet, do it now */
 239         if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 240                 PRINTK(KERN_DEBUG "raid1: sync end %s on sectors %llu-%llu\n",
 241                         (bio_data_dir(bio) == WRITE) ? "write" : "read",
 242                         (unsigned long long) bio->bi_sector,
 243                         (unsigned long long) bio->bi_sector +
 244                                 (bio->bi_size >> 9) - 1);
 245
 246                 bio_endio(bio,
 247                         test_bit(R1BIO_Uptodate, &r1_bio->state) ? 0 : -EIO);
 248         }
 249         free_r1bio(r1_bio);
 250 }
 251
 252 /*
 253  * Update disk head position estimator based on IRQ completion info.
 254  */
 255 static inline void update_head_pos(int disk, r1bio_t *r1_bio)
 256 {
 257         conf_t *conf = r1_bio->mddev->private;
 258
 259         conf->mirrors[disk].head_position =
 260                 r1_bio->sector + (r1_bio->sectors);
 261 }
 262
 263 static void raid1_end_read_request(struct bio *bio, int error)
 264 {
 265         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 266         r1bio_t *r1_bio = bio->bi_private;
 267         int mirror;
 268         conf_t *conf = r1_bio->mddev->private;
 269
 270         mirror = r1_bio->read_disk;
 271         /*
 272          * this branch is our 'one mirror IO has finished' event handler:
 273          */
 274         update_head_pos(mirror, r1_bio);
 275
 276         if (uptodate)
 277                 set_bit(R1BIO_Uptodate, &r1_bio->state);
 278         else {
 279                 /* If all other devices have failed, we want to return
 280                  * the error upwards rather than fail the last device.
 281                  * Here we redefine "uptodate" to mean "Don't want to retry"
 282                  */
 283                 unsigned long flags;
 284                 spin_lock_irqsave(&conf->device_lock, flags);
 285                 if (r1_bio->mddev->degraded == conf->raid_disks ||
 286                     (r1_bio->mddev->degraded == conf->raid_disks-1 &&
 287                      !test_bit(Faulty, &conf->mirrors[mirror].rdev->flags)))
 288                         uptodate = 1;
 289                 spin_unlock_irqrestore(&conf->device_lock, flags);
 290         }
 291
 292         if (uptodate)
 293                 raid_end_bio_io(r1_bio);
 294         else {
 295                 /*
 296                  * oops, read error:
 297                  */
 298                 char b[BDEVNAME_SIZE];
 299                 if (printk_ratelimit())
 300                         printk(KERN_ERR "md/raid1:%s: %s: rescheduling sector %llu\n",
 301                                mdname(conf->mddev),
 302                                bdevname(conf->mirrors[mirror].rdev->bdev,b), (unsigned long long)r1_bio->sector);
 303                 reschedule_retry(r1_bio);
 304         }
 305
 306         rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 307 }
 308
 309 static void r1_bio_write_done(r1bio_t *r1_bio, int vcnt, struct bio_vec *bv,
 310                               int behind)
 311 {
 312         if (atomic_dec_and_test(&r1_bio->remaining))
 313         {
 314                 /* it really is the end of this request */
 315                 if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
 316                         /* free extra copy of the data pages */
 317                         int i = vcnt;
 318                         while (i--)
 319                                 safe_put_page(bv[i].bv_page);
 320                 }
 321                 /* clear the bitmap if all writes complete successfully */
 322                 bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
 323                                 r1_bio->sectors,
 324                                 !test_bit(R1BIO_Degraded, &r1_bio->state),
 325                                 behind);
 326                 md_write_end(r1_bio->mddev);
 327                 raid_end_bio_io(r1_bio);
 328         }
 329 }
 330
 331 static void raid1_end_write_request(struct bio *bio, int error)
 332 {
 333         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 334         r1bio_t *r1_bio = bio->bi_private;
 335         int mirror, behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
 336         conf_t *conf = r1_bio->mddev->private;
 337         struct bio *to_put = NULL;
 338
 339
 340         for (mirror = 0; mirror < conf->raid_disks; mirror++)
 341                 if (r1_bio->bios[mirror] == bio)
 342                         break;
 343
 344         /*
 345          * 'one mirror IO has finished' event handler:
 346          */
 347         r1_bio->bios[mirror] = NULL;
 348         to_put = bio;
 349         if (!uptodate) {
 350                 md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
 351                 /* an I/O failed, we can't clear the bitmap */
 352                 set_bit(R1BIO_Degraded, &r1_bio->state);
 353         } else
 354                 /*
 355                  * Set R1BIO_Uptodate in our master bio, so that we
 356                  * will return a good error code for to the higher
 357                  * levels even if IO on some other mirrored buffer
 358                  * fails.
 359                  *
 360                  * The 'master' represents the composite IO operation
 361                  * to user-side. So if something waits for IO, then it
 362                  * will wait for the 'master' bio.
 363                  */
 364                 set_bit(R1BIO_Uptodate, &r1_bio->state);
 365
 366         update_head_pos(mirror, r1_bio);
 367
 368         if (behind) {
 369                 if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
 370                         atomic_dec(&r1_bio->behind_remaining);
 371
 372                 /*
 373                  * In behind mode, we ACK the master bio once the I/O
 374                  * has safely reached all non-writemostly
 375                  * disks. Setting the Returned bit ensures that this
 376                  * gets done only once -- we don't ever want to return
 377                  * -EIO here, instead we'll wait
 378                  */
 379                 if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
 380                     test_bit(R1BIO_Uptodate, &r1_bio->state)) {
 381                         /* Maybe we can return now */
 382                         if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 383                                 struct bio *mbio = r1_bio->master_bio;
 384                                 PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
 385                                        (unsigned long long) mbio->bi_sector,
 386                                        (unsigned long long) mbio->bi_sector +
 387                                        (mbio->bi_size >> 9) - 1);
 388                                 bio_endio(mbio, 0);
 389                         }
 390                 }
 391         }
 392         rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 393
 394         /*
 395          * Let's see if all mirrored write operations have finished
 396          * already.
 397          */
 398         r1_bio_write_done(r1_bio, bio->bi_vcnt, bio->bi_io_vec, behind);
 399
 400         if (to_put)
 401                 bio_put(to_put);
 402 }
 403
 404
 405 /*
 406  * This routine returns the disk from which the requested read should
 407  * be done. There is a per-array 'next expected sequential IO' sector
 408  * number - if this matches on the next IO then we use the last disk.
 409  * There is also a per-disk 'last know head position' sector that is
 410  * maintained from IRQ contexts, both the normal and the resync IO
 411  * completion handlers update this position correctly. If there is no
 412  * perfect sequential match then we pick the disk whose head is closest.
 413  *
 414  * If there are 2 mirrors in the same 2 devices, performance degrades
 415  * because position is mirror, not device based.
 416  *
 417  * The rdev for the device selected will have nr_pending incremented.
 418  */
 419 static int read_balance(conf_t *conf, r1bio_t *r1_bio)
 420 {
 421         const sector_t this_sector = r1_bio->sector;
 422         const int sectors = r1_bio->sectors;
 423         int new_disk = -1;
 424         int start_disk;
 425         int i;
 426         sector_t new_distance, current_distance;
 427         mdk_rdev_t *rdev;
 428         int choose_first;
 429
 430         rcu_read_lock();
 431         /*
 432          * Check if we can balance. We can balance on the whole
 433          * device if no resync is going on, or below the resync window.
 434          * We take the first readable disk when above the resync window.
 435          */
 436  retry:
 437         if (conf->mddev->recovery_cp < MaxSector &&
 438             (this_sector + sectors >= conf->next_resync)) {
 439                 choose_first = 1;
 440                 start_disk = 0;
 441         } else {
 442                 choose_first = 0;
 443                 start_disk = conf->last_used;
 444         }
 445
 446         /* make sure the disk is operational */
 447         for (i = 0 ; i < conf->raid_disks ; i++) {
 448                 int disk = start_disk + i;
 449                 if (disk >= conf->raid_disks)
 450                         disk -= conf->raid_disks;
 451
 452                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 453                 if (r1_bio->bios[disk] == IO_BLOCKED
 454                     || rdev == NULL
 455                     || !test_bit(In_sync, &rdev->flags))
 456                         continue;
 457
 458                 new_disk = disk;
 459                 if (!test_bit(WriteMostly, &rdev->flags))
 460                         break;
 461         }
 462
 463         if (new_disk < 0 || choose_first)
 464                 goto rb_out;
 465
 466         /*
 467          * Don't change to another disk for sequential reads:
 468          */
 469         if (conf->next_seq_sect == this_sector)
 470                 goto rb_out;
 471         if (this_sector == conf->mirrors[new_disk].head_position)
 472                 goto rb_out;
 473
 474         current_distance = abs(this_sector
 475                                - conf->mirrors[new_disk].head_position);
 476
 477         /* look for a better disk - i.e. head is closer */
 478         start_disk = new_disk;
 479         for (i = 1; i < conf->raid_disks; i++) {
 480                 int disk = start_disk + 1;
 481                 if (disk >= conf->raid_disks)
 482                         disk -= conf->raid_disks;
 483
 484                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 485                 if (r1_bio->bios[disk] == IO_BLOCKED
 486                     || rdev == NULL
 487                     || !test_bit(In_sync, &rdev->flags)
 488                     || test_bit(WriteMostly, &rdev->flags))
 489                         continue;
 490
 491                 if (!atomic_read(&rdev->nr_pending)) {
 492                         new_disk = disk;
 493                         break;
 494                 }
 495                 new_distance = abs(this_sector - conf->mirrors[disk].head_position);
 496                 if (new_distance < current_distance) {
 497                         current_distance = new_distance;
 498                         new_disk = disk;
 499                 }
 500         }
 501
 502  rb_out:
 503         if (new_disk >= 0) {
 504                 rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 505                 if (!rdev)
 506                         goto retry;
 507                 atomic_inc(&rdev->nr_pending);
 508                 if (!test_bit(In_sync, &rdev->flags)) {
 509                         /* cannot risk returning a device that failed
 510                          * before we inc'ed nr_pending
 511                          */
 512                         rdev_dec_pending(rdev, conf->mddev);
 513                         goto retry;
 514                 }
 515                 conf->next_seq_sect = this_sector + sectors;
 516                 conf->last_used = new_disk;
 517         }
 518         rcu_read_unlock();
 519
 520         return new_disk;
 521 }
 522
 523 static void unplug_slaves(mddev_t *mddev)
 524 {
 525         conf_t *conf = mddev->private;
 526         int i;
 527
 528         rcu_read_lock();
 529         for (i=0; i<mddev->raid_disks; i++) {
 530                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 531                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
 532                         struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
 533
 534                         atomic_inc(&rdev->nr_pending);
 535                         rcu_read_unlock();
 536
 537                         blk_unplug(r_queue);
 538
 539                         rdev_dec_pending(rdev, mddev);
 540                         rcu_read_lock();
 541                 }
 542         }
 543         rcu_read_unlock();
 544 }
 545
 546 static void raid1_unplug(struct request_queue *q)
 547 {
 548         mddev_t *mddev = q->queuedata;
 549
 550         unplug_slaves(mddev);
 551         md_wakeup_thread(mddev->thread);
 552 }
 553
 554 static int raid1_congested(void *data, int bits)
 555 {
 556         mddev_t *mddev = data;
 557         conf_t *conf = mddev->private;
 558         int i, ret = 0;
 559
 560         if (mddev_congested(mddev, bits))
 561                 return 1;
 562
 563         rcu_read_lock();
 564         for (i = 0; i < mddev->raid_disks; i++) {
 565                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 566                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 567                         struct request_queue *q = bdev_get_queue(rdev->bdev);
 568
 569                         /* Note the '|| 1' - when read_balance prefers
 570                          * non-congested targets, it can be removed
 571                          */
 572                         if ((bits & (1<<BDI_async_congested)) || 1)
 573                                 ret |= bdi_congested(&q->backing_dev_info, bits);
 574                         else
 575                                 ret &= bdi_congested(&q->backing_dev_info, bits);
 576                 }
 577         }
 578         rcu_read_unlock();
 579         return ret;
 580 }
 581
 582
 583 static int flush_pending_writes(conf_t *conf)
 584 {
 585         /* Any writes that have been queued but are awaiting
 586          * bitmap updates get flushed here.
 587          * We return 1 if any requests were actually submitted.
 588          */
 589         int rv = 0;
 590
 591         spin_lock_irq(&conf->device_lock);
 592
 593         if (conf->pending_bio_list.head) {
 594                 struct bio *bio;
 595                 bio = bio_list_get(&conf->pending_bio_list);
 596                 blk_remove_plug(conf->mddev->queue);
 597                 spin_unlock_irq(&conf->device_lock);
 598                 /* flush any pending bitmap writes to
 599                  * disk before proceeding w/ I/O */
 600                 bitmap_unplug(conf->mddev->bitmap);
 601
 602                 while (bio) { /* submit pending writes */
 603                         struct bio *next = bio->bi_next;
 604                         bio->bi_next = NULL;
 605                         generic_make_request(bio);
 606                         bio = next;
 607                 }
 608                 rv = 1;
 609         } else
 610                 spin_unlock_irq(&conf->device_lock);
 611         return rv;
 612 }
 613
 614 /* Barriers....
 615  * Sometimes we need to suspend IO while we do something else,
 616  * either some resync/recovery, or reconfigure the array.
 617  * To do this we raise a 'barrier'.
 618  * The 'barrier' is a counter that can be raised multiple times
 619  * to count how many activities are happening which preclude
 620  * normal IO.
 621  * We can only raise the barrier if there is no pending IO.
 622  * i.e. if nr_pending == 0.
 623  * We choose only to raise the barrier if no-one is waiting for the
 624  * barrier to go down.  This means that as soon as an IO request
 625  * is ready, no other operations which require a barrier will start
 626  * until the IO request has had a chance.
 627  *
 628  * So: regular IO calls 'wait_barrier'.  When that returns there
 629  *    is no backgroup IO happening,  It must arrange to call
 630  *    allow_barrier when it has finished its IO.
 631  * backgroup IO calls must call raise_barrier.  Once that returns
 632  *    there is no normal IO happeing.  It must arrange to call
 633  *    lower_barrier when the particular background IO completes.
 634  */
 635 #define RESYNC_DEPTH 32
 636
 637 static void raise_barrier(conf_t *conf)
 638 {
 639         spin_lock_irq(&conf->resync_lock);
 640
 641         /* Wait until no block IO is waiting */
 642         wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
 643                             conf->resync_lock,
 644                             raid1_unplug(conf->mddev->queue));
 645
 646         /* block any new IO from starting */
 647         conf->barrier++;
 648
 649         /* Now wait for all pending IO to complete */
 650         wait_event_lock_irq(conf->wait_barrier,
 651                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 652                             conf->resync_lock,
 653                             raid1_unplug(conf->mddev->queue));
 654
 655         spin_unlock_irq(&conf->resync_lock);
 656 }
 657
 658 static void lower_barrier(conf_t *conf)
 659 {
 660         unsigned long flags;
 661         BUG_ON(conf->barrier <= 0);
 662         spin_lock_irqsave(&conf->resync_lock, flags);
 663         conf->barrier--;
 664         spin_unlock_irqrestore(&conf->resync_lock, flags);
 665         wake_up(&conf->wait_barrier);
 666 }
 667
 668 static void wait_barrier(conf_t *conf)
 669 {
 670         spin_lock_irq(&conf->resync_lock);
 671         if (conf->barrier) {
 672                 conf->nr_waiting++;
 673                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
 674                                     conf->resync_lock,
 675                                     raid1_unplug(conf->mddev->queue));
 676                 conf->nr_waiting--;
 677         }
 678         conf->nr_pending++;
 679         spin_unlock_irq(&conf->resync_lock);
 680 }
 681
 682 static void allow_barrier(conf_t *conf)
 683 {
 684         unsigned long flags;
 685         spin_lock_irqsave(&conf->resync_lock, flags);
 686         conf->nr_pending--;
 687         spin_unlock_irqrestore(&conf->resync_lock, flags);
 688         wake_up(&conf->wait_barrier);
 689 }
 690
 691 static void freeze_array(conf_t *conf)
 692 {
 693         /* stop syncio and normal IO and wait for everything to
 694          * go quite.
 695          * We increment barrier and nr_waiting, and then
 696          * wait until nr_pending match nr_queued+1
 697          * This is called in the context of one normal IO request
 698          * that has failed. Thus any sync request that might be pending
 699          * will be blocked by nr_pending, and we need to wait for
 700          * pending IO requests to complete or be queued for re-try.
 701          * Thus the number queued (nr_queued) plus this request (1)
 702          * must match the number of pending IOs (nr_pending) before
 703          * we continue.
 704          */
 705         spin_lock_irq(&conf->resync_lock);
 706         conf->barrier++;
 707         conf->nr_waiting++;
 708         wait_event_lock_irq(conf->wait_barrier,
 709                             conf->nr_pending == conf->nr_queued+1,
 710                             conf->resync_lock,
 711                             ({ flush_pending_writes(conf);
 712                                raid1_unplug(conf->mddev->queue); }));
 713         spin_unlock_irq(&conf->resync_lock);
 714 }
 715 static void unfreeze_array(conf_t *conf)
 716 {
 717         /* reverse the effect of the freeze */
 718         spin_lock_irq(&conf->resync_lock);
 719         conf->barrier--;
 720         conf->nr_waiting--;
 721         wake_up(&conf->wait_barrier);
 722         spin_unlock_irq(&conf->resync_lock);
 723 }
 724
 725
 726 /* duplicate the data pages for behind I/O
 727  * We return a list of bio_vec rather than just page pointers
 728  * as it makes freeing easier
 729  */
 730 static struct bio_vec *alloc_behind_pages(struct bio *bio)
 731 {
 732         int i;
 733         struct bio_vec *bvec;
 734         struct bio_vec *pages = kzalloc(bio->bi_vcnt * sizeof(struct bio_vec),
 735                                         GFP_NOIO);
 736         if (unlikely(!pages))
 737                 goto do_sync_io;
 738
 739         bio_for_each_segment(bvec, bio, i) {
 740                 pages[i].bv_page = alloc_page(GFP_NOIO);
 741                 if (unlikely(!pages[i].bv_page))
 742                         goto do_sync_io;
 743                 memcpy(kmap(pages[i].bv_page) + bvec->bv_offset,
 744                         kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
 745                 kunmap(pages[i].bv_page);
 746                 kunmap(bvec->bv_page);
 747         }
 748
 749         return pages;
 750
 751 do_sync_io:
 752         if (pages)
 753                 for (i = 0; i < bio->bi_vcnt && pages[i].bv_page; i++)
 754                         put_page(pages[i].bv_page);
 755         kfree(pages);
 756         PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
 757         return NULL;
 758 }
 759
 760 static int make_request(mddev_t *mddev, struct bio * bio)
 761 {
 762         conf_t *conf = mddev->private;
 763         mirror_info_t *mirror;
 764         r1bio_t *r1_bio;
 765         struct bio *read_bio;
 766         int i, targets = 0, disks;
 767         struct bitmap *bitmap;
 768         unsigned long flags;
 769         struct bio_vec *behind_pages = NULL;
 770         const int rw = bio_data_dir(bio);
 771         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
 772         const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
 773         mdk_rdev_t *blocked_rdev;
 774
 775         /*
 776          * Register the new request and wait if the reconstruction
 777          * thread has put up a bar for new requests.
 778          * Continue immediately if no resync is active currently.
 779          */
 780
 781         md_write_start(mddev, bio); /* wait on superblock update early */
 782
 783         if (bio_data_dir(bio) == WRITE &&
 784             bio->bi_sector + bio->bi_size/512 > mddev->suspend_lo &&
 785             bio->bi_sector < mddev->suspend_hi) {
 786                 /* As the suspend_* range is controlled by
 787                  * userspace, we want an interruptible
 788                  * wait.
 789                  */
 790                 DEFINE_WAIT(w);
 791                 for (;;) {
 792                         flush_signals(current);
 793                         prepare_to_wait(&conf->wait_barrier,
 794                                         &w, TASK_INTERRUPTIBLE);
 795                         if (bio->bi_sector + bio->bi_size/512 <= mddev->suspend_lo ||
 796                             bio->bi_sector >= mddev->suspend_hi)
 797                                 break;
 798                         schedule();
 799                 }
 800                 finish_wait(&conf->wait_barrier, &w);
 801         }
 802
 803         wait_barrier(conf);
 804
 805         bitmap = mddev->bitmap;
 806
 807         /*
 808          * make_request() can abort the operation when READA is being
 809          * used and no empty request is available.
 810          *
 811          */
 812         r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
 813
 814         r1_bio->master_bio = bio;
 815         r1_bio->sectors = bio->bi_size >> 9;
 816         r1_bio->state = 0;
 817         r1_bio->mddev = mddev;
 818         r1_bio->sector = bio->bi_sector;
 819
 820         if (rw == READ) {
 821                 /*
 822                  * read balancing logic:
 823                  */
 824                 int rdisk = read_balance(conf, r1_bio);
 825
 826                 if (rdisk < 0) {
 827                         /* couldn't find anywhere to read from */
 828                         raid_end_bio_io(r1_bio);
 829                         return 0;
 830                 }
 831                 mirror = conf->mirrors + rdisk;
 832
 833                 if (test_bit(WriteMostly, &mirror->rdev->flags) &&
 834                     bitmap) {
 835                         /* Reading from a write-mostly device must
 836                          * take care not to over-take any writes
 837                          * that are 'behind'
 838                          */
 839                         wait_event(bitmap->behind_wait,
 840                                    atomic_read(&bitmap->behind_writes) == 0);
 841                 }
 842                 r1_bio->read_disk = rdisk;
 843
 844                 read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
 845
 846                 r1_bio->bios[rdisk] = read_bio;
 847
 848                 read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
 849                 read_bio->bi_bdev = mirror->rdev->bdev;
 850                 read_bio->bi_end_io = raid1_end_read_request;
 851                 read_bio->bi_rw = READ | do_sync;
 852                 read_bio->bi_private = r1_bio;
 853
 854                 generic_make_request(read_bio);
 855                 return 0;
 856         }
 857
 858         /*
 859          * WRITE:
 860          */
 861         /* first select target devices under spinlock and
 862          * inc refcount on their rdev.  Record them by setting
 863          * bios[x] to bio
 864          */
 865         disks = conf->raid_disks;
 866  retry_write:
 867         blocked_rdev = NULL;
 868         rcu_read_lock();
 869         for (i = 0;  i < disks; i++) {
 870                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 871                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
 872                         atomic_inc(&rdev->nr_pending);
 873                         blocked_rdev = rdev;
 874                         break;
 875                 }
 876                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 877                         atomic_inc(&rdev->nr_pending);
 878                         if (test_bit(Faulty, &rdev->flags)) {
 879                                 rdev_dec_pending(rdev, mddev);
 880                                 r1_bio->bios[i] = NULL;
 881                         } else {
 882                                 r1_bio->bios[i] = bio;
 883                                 targets++;
 884                         }
 885                 } else
 886                         r1_bio->bios[i] = NULL;
 887         }
 888         rcu_read_unlock();
 889
 890         if (unlikely(blocked_rdev)) {
 891                 /* Wait for this device to become unblocked */
 892                 int j;
 893
 894                 for (j = 0; j < i; j++)
 895                         if (r1_bio->bios[j])
 896                                 rdev_dec_pending(conf->mirrors[j].rdev, mddev);
 897
 898                 allow_barrier(conf);
 899                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
 900                 wait_barrier(conf);
 901                 goto retry_write;
 902         }
 903
 904         BUG_ON(targets == 0); /* we never fail the last device */
 905
 906         if (targets < conf->raid_disks) {
 907                 /* array is degraded, we will not clear the bitmap
 908                  * on I/O completion (see raid1_end_write_request) */
 909                 set_bit(R1BIO_Degraded, &r1_bio->state);
 910         }
 911
 912         /* do behind I/O ?
 913          * Not if there are too many, or cannot allocate memory,
 914          * or a reader on WriteMostly is waiting for behind writes
 915          * to flush */
 916         if (bitmap &&
 917             (atomic_read(&bitmap->behind_writes)
 918              < mddev->bitmap_info.max_write_behind) &&
 919             !waitqueue_active(&bitmap->behind_wait) &&
 920             (behind_pages = alloc_behind_pages(bio)) != NULL)
 921                 set_bit(R1BIO_BehindIO, &r1_bio->state);
 922
 923         atomic_set(&r1_bio->remaining, 1);
 924         atomic_set(&r1_bio->behind_remaining, 0);
 925
 926         bitmap_startwrite(bitmap, bio->bi_sector, r1_bio->sectors,
 927                                 test_bit(R1BIO_BehindIO, &r1_bio->state));
 928         for (i = 0; i < disks; i++) {
 929                 struct bio *mbio;
 930                 if (!r1_bio->bios[i])
 931                         continue;
 932
 933                 mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
 934                 r1_bio->bios[i] = mbio;
 935
 936                 mbio->bi_sector = r1_bio->sector + conf->mirrors[i].rdev->data_offset;
 937                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
 938                 mbio->bi_end_io = raid1_end_write_request;
 939                 mbio->bi_rw = WRITE | do_flush_fua | do_sync;
 940                 mbio->bi_private = r1_bio;
 941
 942                 if (behind_pages) {
 943                         struct bio_vec *bvec;
 944                         int j;
 945
 946                         /* Yes, I really want the '__' version so that
 947                          * we clear any unused pointer in the io_vec, rather
 948                          * than leave them unchanged.  This is important
 949                          * because when we come to free the pages, we won't
 950                          * know the original bi_idx, so we just free
 951                          * them all
 952                          */
 953                         __bio_for_each_segment(bvec, mbio, j, 0)
 954                                 bvec->bv_page = behind_pages[j].bv_page;
 955                         if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
 956                                 atomic_inc(&r1_bio->behind_remaining);
 957                 }
 958
 959                 atomic_inc(&r1_bio->remaining);
 960                 spin_lock_irqsave(&conf->device_lock, flags);
 961                 bio_list_add(&conf->pending_bio_list, mbio);
 962                 blk_plug_device(mddev->queue);
 963                 spin_unlock_irqrestore(&conf->device_lock, flags);
 964         }
 965         r1_bio_write_done(r1_bio, bio->bi_vcnt, behind_pages, behind_pages != NULL);
 966         kfree(behind_pages); /* the behind pages are attached to the bios now */
 967
 968         /* In case raid1d snuck in to freeze_array */
 969         wake_up(&conf->wait_barrier);
 970
 971         if (do_sync)
 972                 md_wakeup_thread(mddev->thread);
 973
 974         return 0;
 975 }
 976
 977 static void status(struct seq_file *seq, mddev_t *mddev)
 978 {
 979         conf_t *conf = mddev->private;
 980         int i;
 981
 982         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 983                    conf->raid_disks - mddev->degraded);
 984         rcu_read_lock();
 985         for (i = 0; i < conf->raid_disks; i++) {
 986                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 987                 seq_printf(seq, "%s",
 988                            rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
 989         }
 990         rcu_read_unlock();
 991         seq_printf(seq, "]");
 992 }
 993
 994
 995 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 996 {
 997         char b[BDEVNAME_SIZE];
 998         conf_t *conf = mddev->private;
 999
1000         /*
1001          * If it is not operational, then we have already marked it as dead
1002          * else if it is the last working disks, ignore the error, let the
1003          * next level up know.
1004          * else mark the drive as failed
1005          */
1006         if (test_bit(In_sync, &rdev->flags)
1007             && (conf->raid_disks - mddev->degraded) == 1) {
1008                 /*
1009                  * Don't fail the drive, act as though we were just a
1010                  * normal single drive.
1011                  * However don't try a recovery from this drive as
1012                  * it is very likely to fail.
1013                  */
1014                 mddev->recovery_disabled = 1;
1015                 return;
1016         }
1017         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1018                 unsigned long flags;
1019                 spin_lock_irqsave(&conf->device_lock, flags);
1020                 mddev->degraded++;
1021                 set_bit(Faulty, &rdev->flags);
1022                 spin_unlock_irqrestore(&conf->device_lock, flags);
1023                 /*
1024                  * if recovery is running, make sure it aborts.
1025                  */
1026                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1027         } else
1028                 set_bit(Faulty, &rdev->flags);
1029         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1030         printk(KERN_ALERT
1031                "md/raid1:%s: Disk failure on %s, disabling device.\n"
1032                "md/raid1:%s: Operation continuing on %d devices.\n",
1033                mdname(mddev), bdevname(rdev->bdev, b),
1034                mdname(mddev), conf->raid_disks - mddev->degraded);
1035 }
1036
1037 static void print_conf(conf_t *conf)
1038 {
1039         int i;
1040
1041         printk(KERN_DEBUG "RAID1 conf printout:\n");
1042         if (!conf) {
1043                 printk(KERN_DEBUG "(!conf)\n");
1044                 return;
1045         }
1046         printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1047                 conf->raid_disks);
1048
1049         rcu_read_lock();
1050         for (i = 0; i < conf->raid_disks; i++) {
1051                 char b[BDEVNAME_SIZE];
1052                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
1053                 if (rdev)
1054                         printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1055                                i, !test_bit(In_sync, &rdev->flags),
1056                                !test_bit(Faulty, &rdev->flags),
1057                                bdevname(rdev->bdev,b));
1058         }
1059         rcu_read_unlock();
1060 }
1061
1062 static void close_sync(conf_t *conf)
1063 {
1064         wait_barrier(conf);
1065         allow_barrier(conf);
1066
1067         mempool_destroy(conf->r1buf_pool);
1068         conf->r1buf_pool = NULL;
1069 }
1070
1071 static int raid1_spare_active(mddev_t *mddev)
1072 {
1073         int i;
1074         conf_t *conf = mddev->private;
1075         int count = 0;
1076         unsigned long flags;
1077
1078         /*
1079          * Find all failed disks within the RAID1 configuration
1080          * and mark them readable.
1081          * Called under mddev lock, so rcu protection not needed.
1082          */
1083         for (i = 0; i < conf->raid_disks; i++) {
1084                 mdk_rdev_t *rdev = conf->mirrors[i].rdev;
1085                 if (rdev
1086                     && !test_bit(Faulty, &rdev->flags)
1087                     && !test_and_set_bit(In_sync, &rdev->flags)) {
1088                         count++;
1089                         sysfs_notify_dirent(rdev->sysfs_state);
1090                 }
1091         }
1092         spin_lock_irqsave(&conf->device_lock, flags);
1093         mddev->degraded -= count;
1094         spin_unlock_irqrestore(&conf->device_lock, flags);
1095
1096         print_conf(conf);
1097         return count;
1098 }
1099
1100
1101 static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1102 {
1103         conf_t *conf = mddev->private;
1104         int err = -EEXIST;
1105         int mirror = 0;
1106         mirror_info_t *p;
1107         int first = 0;
1108         int last = mddev->raid_disks - 1;
1109
1110         if (rdev->raid_disk >= 0)
1111                 first = last = rdev->raid_disk;
1112
1113         for (mirror = first; mirror <= last; mirror++)
1114                 if ( !(p=conf->mirrors+mirror)->rdev) {
1115
1116                         disk_stack_limits(mddev->gendisk, rdev->bdev,
1117                                           rdev->data_offset << 9);
1118                         /* as we don't honour merge_bvec_fn, we must
1119                          * never risk violating it, so limit
1120                          * ->max_segments to one lying with a single
1121                          * page, as a one page request is never in
1122                          * violation.
1123                          */
1124                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
1125                                 blk_queue_max_segments(mddev->queue, 1);
1126                                 blk_queue_segment_boundary(mddev->queue,
1127                                                            PAGE_CACHE_SIZE - 1);
1128                         }
1129
1130                         p->head_position = 0;
1131                         rdev->raid_disk = mirror;
1132                         err = 0;
1133                         /* As all devices are equivalent, we don't need a full recovery
1134                          * if this was recently any drive of the array
1135                          */
1136                         if (rdev->saved_raid_disk < 0)
1137                                 conf->fullsync = 1;
1138                         rcu_assign_pointer(p->rdev, rdev);
1139                         break;
1140                 }
1141         md_integrity_add_rdev(rdev, mddev);
1142         print_conf(conf);
1143         return err;
1144 }
1145
1146 static int raid1_remove_disk(mddev_t *mddev, int number)
1147 {
1148         conf_t *conf = mddev->private;
1149         int err = 0;
1150         mdk_rdev_t *rdev;
1151         mirror_info_t *p = conf->mirrors+ number;
1152
1153         print_conf(conf);
1154         rdev = p->rdev;
1155         if (rdev) {
1156                 if (test_bit(In_sync, &rdev->flags) ||
1157                     atomic_read(&rdev->nr_pending)) {
1158                         err = -EBUSY;
1159                         goto abort;
1160                 }
1161                 /* Only remove non-faulty devices if recovery
1162                  * is not possible.
1163                  */
1164                 if (!test_bit(Faulty, &rdev->flags) &&
1165                     !mddev->recovery_disabled &&
1166                     mddev->degraded < conf->raid_disks) {
1167                         err = -EBUSY;
1168                         goto abort;
1169                 }
1170                 p->rdev = NULL;
1171                 synchronize_rcu();
1172                 if (atomic_read(&rdev->nr_pending)) {
1173                         /* lost the race, try later */
1174                         err = -EBUSY;
1175                         p->rdev = rdev;
1176                         goto abort;
1177                 }
1178                 md_integrity_register(mddev);
1179         }
1180 abort:
1181
1182         print_conf(conf);
1183         return err;
1184 }
1185
1186
1187 static void end_sync_read(struct bio *bio, int error)
1188 {
1189         r1bio_t *r1_bio = bio->bi_private;
1190         int i;
1191
1192         for (i=r1_bio->mddev->raid_disks; i--; )
1193                 if (r1_bio->bios[i] == bio)
1194                         break;
1195         BUG_ON(i < 0);
1196         update_head_pos(i, r1_bio);
1197         /*
1198          * we have read a block, now it needs to be re-written,
1199          * or re-read if the read failed.
1200          * We don't do much here, just schedule handling by raid1d
1201          */
1202         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1203                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1204
1205         if (atomic_dec_and_test(&r1_bio->remaining))
1206                 reschedule_retry(r1_bio);
1207 }
1208
1209 static void end_sync_write(struct bio *bio, int error)
1210 {
1211         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1212         r1bio_t *r1_bio = bio->bi_private;
1213         mddev_t *mddev = r1_bio->mddev;
1214         conf_t *conf = mddev->private;
1215         int i;
1216         int mirror=0;
1217
1218         for (i = 0; i < conf->raid_disks; i++)
1219                 if (r1_bio->bios[i] == bio) {
1220                         mirror = i;
1221                         break;
1222                 }
1223         if (!uptodate) {
1224                 sector_t sync_blocks = 0;
1225                 sector_t s = r1_bio->sector;
1226                 long sectors_to_go = r1_bio->sectors;
1227                 /* make sure these bits doesn't get cleared. */
1228                 do {
1229                         bitmap_end_sync(mddev->bitmap, s,
1230                                         &sync_blocks, 1);
1231                         s += sync_blocks;
1232                         sectors_to_go -= sync_blocks;
1233                 } while (sectors_to_go > 0);
1234                 md_error(mddev, conf->mirrors[mirror].rdev);
1235         }
1236
1237         update_head_pos(mirror, r1_bio);
1238
1239         if (atomic_dec_and_test(&r1_bio->remaining)) {
1240                 sector_t s = r1_bio->sectors;
1241                 put_buf(r1_bio);
1242                 md_done_sync(mddev, s, uptodate);
1243         }
1244 }
1245
1246 static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
1247 {
1248         conf_t *conf = mddev->private;
1249         int i;
1250         int disks = conf->raid_disks;
1251         struct bio *bio, *wbio;
1252
1253         bio = r1_bio->bios[r1_bio->read_disk];
1254
1255
1256         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1257                 /* We have read all readable devices.  If we haven't
1258                  * got the block, then there is no hope left.
1259                  * If we have, then we want to do a comparison
1260                  * and skip the write if everything is the same.
1261                  * If any blocks failed to read, then we need to
1262                  * attempt an over-write
1263                  */
1264                 int primary;
1265                 if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
1266                         for (i=0; i<mddev->raid_disks; i++)
1267                                 if (r1_bio->bios[i]->bi_end_io == end_sync_read)
1268                                         md_error(mddev, conf->mirrors[i].rdev);
1269
1270                         md_done_sync(mddev, r1_bio->sectors, 1);
1271                         put_buf(r1_bio);
1272                         return;
1273                 }
1274                 for (primary=0; primary<mddev->raid_disks; primary++)
1275                         if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
1276                             test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
1277                                 r1_bio->bios[primary]->bi_end_io = NULL;
1278                                 rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
1279                                 break;
1280                         }
1281                 r1_bio->read_disk = primary;
1282                 for (i=0; i<mddev->raid_disks; i++)
1283                         if (r1_bio->bios[i]->bi_end_io == end_sync_read) {
1284                                 int j;
1285                                 int vcnt = r1_bio->sectors >> (PAGE_SHIFT- 9);
1286                                 struct bio *pbio = r1_bio->bios[primary];
1287                                 struct bio *sbio = r1_bio->bios[i];
1288
1289                                 if (test_bit(BIO_UPTODATE, &sbio->bi_flags)) {
1290                                         for (j = vcnt; j-- ; ) {
1291                                                 struct page *p, *s;
1292                                                 p = pbio->bi_io_vec[j].bv_page;
1293                                                 s = sbio->bi_io_vec[j].bv_page;
1294                                                 if (memcmp(page_address(p),
1295                                                            page_address(s),
1296                                                            PAGE_SIZE))
1297                                                         break;
1298                                         }
1299                                 } else
1300                                         j = 0;
1301                                 if (j >= 0)
1302                                         mddev->resync_mismatches += r1_bio->sectors;
1303                                 if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
1304                                               && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {
1305                                         sbio->bi_end_io = NULL;
1306                                         rdev_dec_pending(conf->mirrors[i].rdev, mddev);
1307                                 } else {
1308                                         /* fixup the bio for reuse */
1309                                         int size;
1310                                         sbio->bi_vcnt = vcnt;
1311                                         sbio->bi_size = r1_bio->sectors << 9;
1312                                         sbio->bi_idx = 0;
1313                                         sbio->bi_phys_segments = 0;
1314                                         sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1315                                         sbio->bi_flags |= 1 << BIO_UPTODATE;
1316                                         sbio->bi_next = NULL;
1317                                         sbio->bi_sector = r1_bio->sector +
1318                                                 conf->mirrors[i].rdev->data_offset;
1319                                         sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
1320                                         size = sbio->bi_size;
1321                                         for (j = 0; j < vcnt ; j++) {
1322                                                 struct bio_vec *bi;
1323                                                 bi = &sbio->bi_io_vec[j];
1324                                                 bi->bv_offset = 0;
1325                                                 if (size > PAGE_SIZE)
1326                                                         bi->bv_len = PAGE_SIZE;
1327                                                 else
1328                                                         bi->bv_len = size;
1329                                                 size -= PAGE_SIZE;
1330                                                 memcpy(page_address(bi->bv_page),
1331                                                        page_address(pbio->bi_io_vec[j].bv_page),
1332                                                        PAGE_SIZE);
1333                                         }
1334
1335                                 }
1336                         }
1337         }
1338         if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
1339                 /* ouch - failed to read all of that.
1340                  * Try some synchronous reads of other devices to get
1341                  * good data, much like with normal read errors.  Only
1342                  * read into the pages we already have so we don't
1343                  * need to re-issue the read request.
1344                  * We don't need to freeze the array, because being in an
1345                  * active sync request, there is no normal IO, and
1346                  * no overlapping syncs.
1347                  */
1348                 sector_t sect = r1_bio->sector;
1349                 int sectors = r1_bio->sectors;
1350                 int idx = 0;
1351
1352                 while(sectors) {
1353                         int s = sectors;
1354                         int d = r1_bio->read_disk;
1355                         int success = 0;
1356                         mdk_rdev_t *rdev;
1357
1358                         if (s > (PAGE_SIZE>>9))
1359                                 s = PAGE_SIZE >> 9;
1360                         do {
1361                                 if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
1362                                         /* No rcu protection needed here devices
1363                                          * can only be removed when no resync is
1364                                          * active, and resync is currently active
1365                                          */
1366                                         rdev = conf->mirrors[d].rdev;
1367                                         if (sync_page_io(rdev,
1368                                                          sect,
1369                                                          s<<9,
1370                                                          bio->bi_io_vec[idx].bv_page,
1371                                                          READ, false)) {
1372                                                 success = 1;
1373                                                 break;
1374                                         }
1375                                 }
1376                                 d++;
1377                                 if (d == conf->raid_disks)
1378                                         d = 0;
1379                         } while (!success && d != r1_bio->read_disk);
1380
1381                         if (success) {
1382                                 int start = d;
1383                                 /* write it back and re-read */
1384                                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1385                                 while (d != r1_bio->read_disk) {
1386                                         if (d == 0)
1387                                                 d = conf->raid_disks;
1388                                         d--;
1389                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1390                                                 continue;
1391                                         rdev = conf->mirrors[d].rdev;
1392                                         atomic_add(s, &rdev->corrected_errors);
1393                                         if (sync_page_io(rdev,
1394                                                          sect,
1395                                                          s<<9,
1396                                                          bio->bi_io_vec[idx].bv_page,
1397                                                          WRITE, false) == 0)
1398                                                 md_error(mddev, rdev);
1399                                 }
1400                                 d = start;
1401                                 while (d != r1_bio->read_disk) {
1402                                         if (d == 0)
1403                                                 d = conf->raid_disks;
1404                                         d--;
1405                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1406                                                 continue;
1407                                         rdev = conf->mirrors[d].rdev;
1408                                         if (sync_page_io(rdev,
1409                                                          sect,
1410                                                          s<<9,
1411                                                          bio->bi_io_vec[idx].bv_page,
1412                                                          READ, false) == 0)
1413                                                 md_error(mddev, rdev);
1414                                 }
1415                         } else {
1416                                 char b[BDEVNAME_SIZE];
1417                                 /* Cannot read from anywhere, array is toast */
1418                                 md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
1419                                 printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O read error"
1420                                        " for block %llu\n",
1421                                        mdname(mddev),
1422                                        bdevname(bio->bi_bdev, b),
1423                                        (unsigned long long)r1_bio->sector);
1424                                 md_done_sync(mddev, r1_bio->sectors, 0);
1425                                 put_buf(r1_bio);
1426                                 return;
1427                         }
1428                         sectors -= s;
1429                         sect += s;
1430                         idx ++;
1431                 }
1432         }
1433
1434         /*
1435          * schedule writes
1436          */
1437         atomic_set(&r1_bio->remaining, 1);
1438         for (i = 0; i < disks ; i++) {
1439                 wbio = r1_bio->bios[i];
1440                 if (wbio->bi_end_io == NULL ||
1441                     (wbio->bi_end_io == end_sync_read &&
1442                      (i == r1_bio->read_disk ||
1443                       !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
1444                         continue;
1445
1446                 wbio->bi_rw = WRITE;
1447                 wbio->bi_end_io = end_sync_write;
1448                 atomic_inc(&r1_bio->remaining);
1449                 md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
1450
1451                 generic_make_request(wbio);
1452         }
1453
1454         if (atomic_dec_and_test(&r1_bio->remaining)) {
1455                 /* if we're here, all write(s) have completed, so clean up */
1456                 md_done_sync(mddev, r1_bio->sectors, 1);
1457                 put_buf(r1_bio);
1458         }
1459 }
1460
1461 /*
1462  * This is a kernel thread which:
1463  *
1464  *      1.      Retries failed read operations on working mirrors.
1465  *      2.      Updates the raid superblock when problems encounter.
1466  *      3.      Performs writes following reads for array syncronising.
1467  */
1468
1469 static void fix_read_error(conf_t *conf, int read_disk,
1470                            sector_t sect, int sectors)
1471 {
1472         mddev_t *mddev = conf->mddev;
1473         while(sectors) {
1474                 int s = sectors;
1475                 int d = read_disk;
1476                 int success = 0;
1477                 int start;
1478                 mdk_rdev_t *rdev;
1479
1480                 if (s > (PAGE_SIZE>>9))
1481                         s = PAGE_SIZE >> 9;
1482
1483                 do {
1484                         /* Note: no rcu protection needed here
1485                          * as this is synchronous in the raid1d thread
1486                          * which is the thread that might remove
1487                          * a device.  If raid1d ever becomes multi-threaded....
1488                          */
1489                         rdev = conf->mirrors[d].rdev;
1490                         if (rdev &&
1491                             test_bit(In_sync, &rdev->flags) &&
1492                             sync_page_io(rdev, sect, s<<9,
1493                                          conf->tmppage, READ, false))
1494                                 success = 1;
1495                         else {
1496                                 d++;
1497                                 if (d == conf->raid_disks)
1498                                         d = 0;
1499                         }
1500                 } while (!success && d != read_disk);
1501
1502                 if (!success) {
1503                         /* Cannot read from anywhere -- bye bye array */
1504                         md_error(mddev, conf->mirrors[read_disk].rdev);
1505                         break;
1506                 }
1507                 /* write it back and re-read */
1508                 start = d;
1509                 while (d != read_disk) {
1510                         if (d==0)
1511                                 d = conf->raid_disks;
1512                         d--;
1513                         rdev = conf->mirrors[d].rdev;
1514                         if (rdev &&
1515                             test_bit(In_sync, &rdev->flags)) {
1516                                 if (sync_page_io(rdev, sect, s<<9,
1517                                                  conf->tmppage, WRITE, false)
1518                                     == 0)
1519                                         /* Well, this device is dead */
1520                                         md_error(mddev, rdev);
1521                         }
1522                 }
1523                 d = start;
1524                 while (d != read_disk) {
1525                         char b[BDEVNAME_SIZE];
1526                         if (d==0)
1527                                 d = conf->raid_disks;
1528                         d--;
1529                         rdev = conf->mirrors[d].rdev;
1530                         if (rdev &&
1531                             test_bit(In_sync, &rdev->flags)) {
1532                                 if (sync_page_io(rdev, sect, s<<9,
1533                                                  conf->tmppage, READ, false)
1534                                     == 0)
1535                                         /* Well, this device is dead */
1536                                         md_error(mddev, rdev);
1537                                 else {
1538                                         atomic_add(s, &rdev->corrected_errors);
1539                                         printk(KERN_INFO
1540                                                "md/raid1:%s: read error corrected "
1541                                                "(%d sectors at %llu on %s)\n",
1542                                                mdname(mddev), s,
1543                                                (unsigned long long)(sect +
1544                                                    rdev->data_offset),
1545                                                bdevname(rdev->bdev, b));
1546                                 }
1547                         }
1548                 }
1549                 sectors -= s;
1550                 sect += s;
1551         }
1552 }
1553
1554 static void raid1d(mddev_t *mddev)
1555 {
1556         r1bio_t *r1_bio;
1557         struct bio *bio;
1558         unsigned long flags;
1559         conf_t *conf = mddev->private;
1560         struct list_head *head = &conf->retry_list;
1561         int unplug=0;
1562         mdk_rdev_t *rdev;
1563
1564         md_check_recovery(mddev);
1565
1566         for (;;) {
1567                 char b[BDEVNAME_SIZE];
1568
1569                 unplug += flush_pending_writes(conf);
1570
1571                 spin_lock_irqsave(&conf->device_lock, flags);
1572                 if (list_empty(head)) {
1573                         spin_unlock_irqrestore(&conf->device_lock, flags);
1574                         break;
1575                 }
1576                 r1_bio = list_entry(head->prev, r1bio_t, retry_list);
1577                 list_del(head->prev);
1578                 conf->nr_queued--;
1579                 spin_unlock_irqrestore(&conf->device_lock, flags);
1580
1581                 mddev = r1_bio->mddev;
1582                 conf = mddev->private;
1583                 if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
1584                         sync_request_write(mddev, r1_bio);
1585                         unplug = 1;
1586                 } else {
1587                         int disk;
1588
1589                         /* we got a read error. Maybe the drive is bad.  Maybe just
1590                          * the block and we can fix it.
1591                          * We freeze all other IO, and try reading the block from
1592                          * other devices.  When we find one, we re-write
1593                          * and check it that fixes the read error.
1594                          * This is all done synchronously while the array is
1595                          * frozen
1596                          */
1597                         if (mddev->ro == 0) {
1598                                 freeze_array(conf);
1599                                 fix_read_error(conf, r1_bio->read_disk,
1600                                                r1_bio->sector,
1601                                                r1_bio->sectors);
1602                                 unfreeze_array(conf);
1603                         } else
1604                                 md_error(mddev,
1605                                          conf->mirrors[r1_bio->read_disk].rdev);
1606
1607                         bio = r1_bio->bios[r1_bio->read_disk];
1608                         if ((disk=read_balance(conf, r1_bio)) == -1) {
1609                                 printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O"
1610                                        " read error for block %llu\n",
1611                                        mdname(mddev),
1612                                        bdevname(bio->bi_bdev,b),
1613                                        (unsigned long long)r1_bio->sector);
1614                                 raid_end_bio_io(r1_bio);
1615                         } else {
1616                                 const unsigned long do_sync = r1_bio->master_bio->bi_rw & REQ_SYNC;
1617                                 r1_bio->bios[r1_bio->read_disk] =
1618                                         mddev->ro ? IO_BLOCKED : NULL;
1619                                 r1_bio->read_disk = disk;
1620                                 bio_put(bio);
1621                                 bio = bio_clone_mddev(r1_bio->master_bio,
1622                                                       GFP_NOIO, mddev);
1623                                 r1_bio->bios[r1_bio->read_disk] = bio;
1624                                 rdev = conf->mirrors[disk].rdev;
1625                                 if (printk_ratelimit())
1626                                         printk(KERN_ERR "md/raid1:%s: redirecting sector %llu to"
1627                                                " other mirror: %s\n",
1628                                                mdname(mddev),
1629                                                (unsigned long long)r1_bio->sector,
1630                                                bdevname(rdev->bdev,b));
1631                                 bio->bi_sector = r1_bio->sector + rdev->data_offset;
1632                                 bio->bi_bdev = rdev->bdev;
1633                                 bio->bi_end_io = raid1_end_read_request;
1634                                 bio->bi_rw = READ | do_sync;
1635                                 bio->bi_private = r1_bio;
1636                                 unplug = 1;
1637                                 generic_make_request(bio);
1638                         }
1639                 }
1640                 cond_resched();
1641         }
1642         if (unplug)
1643                 unplug_slaves(mddev);
1644 }
1645
1646
1647 static int init_resync(conf_t *conf)
1648 {
1649         int buffs;
1650
1651         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1652         BUG_ON(conf->r1buf_pool);
1653         conf->r1buf_pool = mempool_create(buffs, r1buf_pool_alloc, r1buf_pool_free,
1654                                           conf->poolinfo);
1655         if (!conf->r1buf_pool)
1656                 return -ENOMEM;
1657         conf->next_resync = 0;
1658         return 0;
1659 }
1660
1661 /*
1662  * perform a "sync" on one "block"
1663  *
1664  * We need to make sure that no normal I/O request - particularly write
1665  * requests - conflict with active sync requests.
1666  *
1667  * This is achieved by tracking pending requests and a 'barrier' concept
1668  * that can be installed to exclude normal IO requests.
1669  */
1670
1671 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1672 {
1673         conf_t *conf = mddev->private;
1674         r1bio_t *r1_bio;
1675         struct bio *bio;
1676         sector_t max_sector, nr_sectors;
1677         int disk = -1;
1678         int i;
1679         int wonly = -1;
1680         int write_targets = 0, read_targets = 0;
1681         sector_t sync_blocks;
1682         int still_degraded = 0;
1683
1684         if (!conf->r1buf_pool)
1685                 if (init_resync(conf))
1686                         return 0;
1687
1688         max_sector = mddev->dev_sectors;
1689         if (sector_nr >= max_sector) {
1690                 /* If we aborted, we need to abort the
1691                  * sync on the 'current' bitmap chunk (there will
1692                  * only be one in raid1 resync.
1693                  * We can find the current addess in mddev->curr_resync
1694                  */
1695                 if (mddev->curr_resync < max_sector) /* aborted */
1696                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1697                                                 &sync_blocks, 1);
1698                 else /* completed sync */
1699                         conf->fullsync = 0;
1700
1701                 bitmap_close_sync(mddev->bitmap);
1702                 close_sync(conf);
1703                 return 0;
1704         }
1705
1706         if (mddev->bitmap == NULL &&
1707             mddev->recovery_cp == MaxSector &&
1708             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
1709             conf->fullsync == 0) {
1710                 *skipped = 1;
1711                 return max_sector - sector_nr;
1712         }
1713         /* before building a request, check if we can skip these blocks..
1714          * This call the bitmap_start_sync doesn't actually record anything
1715          */
1716         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1717             !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1718                 /* We can skip this block, and probably several more */
1719                 *skipped = 1;
1720                 return sync_blocks;
1721         }
1722         /*
1723          * If there is non-resync activity waiting for a turn,
1724          * and resync is going fast enough,
1725          * then let it though before starting on this new sync request.
1726          */
1727         if (!go_faster && conf->nr_waiting)
1728                 msleep_interruptible(1000);
1729
1730         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
1731         r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
1732         raise_barrier(conf);
1733
1734         conf->next_resync = sector_nr;
1735
1736         rcu_read_lock();
1737         /*
1738          * If we get a correctably read error during resync or recovery,
1739          * we might want to read from a different device.  So we
1740          * flag all drives that could conceivably be read from for READ,
1741          * and any others (which will be non-In_sync devices) for WRITE.
1742          * If a read fails, we try reading from something else for which READ
1743          * is OK.
1744          */
1745
1746         r1_bio->mddev = mddev;
1747         r1_bio->sector = sector_nr;
1748         r1_bio->state = 0;
1749         set_bit(R1BIO_IsSync, &r1_bio->state);
1750
1751         for (i=0; i < conf->raid_disks; i++) {
1752                 mdk_rdev_t *rdev;
1753                 bio = r1_bio->bios[i];
1754
1755                 /* take from bio_init */
1756                 bio->bi_next = NULL;
1757                 bio->bi_flags &= ~(BIO_POOL_MASK-1);
1758                 bio->bi_flags |= 1 << BIO_UPTODATE;
1759                 bio->bi_comp_cpu = -1;
1760                 bio->bi_rw = READ;
1761                 bio->bi_vcnt = 0;
1762                 bio->bi_idx = 0;
1763                 bio->bi_phys_segments = 0;
1764                 bio->bi_size = 0;
1765                 bio->bi_end_io = NULL;
1766                 bio->bi_private = NULL;
1767
1768                 rdev = rcu_dereference(conf->mirrors[i].rdev);
1769                 if (rdev == NULL ||
1770                            test_bit(Faulty, &rdev->flags)) {
1771                         still_degraded = 1;
1772                         continue;
1773                 } else if (!test_bit(In_sync, &rdev->flags)) {
1774                         bio->bi_rw = WRITE;
1775                         bio->bi_end_io = end_sync_write;
1776                         write_targets ++;
1777                 } else {
1778                         /* may need to read from here */
1779                         bio->bi_rw = READ;
1780                         bio->bi_end_io = end_sync_read;
1781                         if (test_bit(WriteMostly, &rdev->flags)) {
1782                                 if (wonly < 0)
1783                                         wonly = i;
1784                         } else {
1785                                 if (disk < 0)
1786                                         disk = i;
1787                         }
1788                         read_targets++;
1789                 }
1790                 atomic_inc(&rdev->nr_pending);
1791                 bio->bi_sector = sector_nr + rdev->data_offset;
1792                 bio->bi_bdev = rdev->bdev;
1793                 bio->bi_private = r1_bio;
1794         }
1795         rcu_read_unlock();
1796         if (disk < 0)
1797                 disk = wonly;
1798         r1_bio->read_disk = disk;
1799
1800         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
1801                 /* extra read targets are also write targets */
1802                 write_targets += read_targets-1;
1803
1804         if (write_targets == 0 || read_targets == 0) {
1805                 /* There is nowhere to write, so all non-sync
1806                  * drives must be failed - so we are finished
1807                  */
1808                 sector_t rv = max_sector - sector_nr;
1809                 *skipped = 1;
1810                 put_buf(r1_bio);
1811                 return rv;
1812         }
1813
1814         if (max_sector > mddev->resync_max)
1815                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
1816         nr_sectors = 0;
1817         sync_blocks = 0;
1818         do {
1819                 struct page *page;
1820                 int len = PAGE_SIZE;
1821                 if (sector_nr + (len>>9) > max_sector)
1822                         len = (max_sector - sector_nr) << 9;
1823                 if (len == 0)
1824                         break;
1825                 if (sync_blocks == 0) {
1826                         if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1827                                                &sync_blocks, still_degraded) &&
1828                             !conf->fullsync &&
1829                             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
1830                                 break;
1831                         BUG_ON(sync_blocks < (PAGE_SIZE>>9));
1832                         if ((len >> 9) > sync_blocks)
1833                                 len = sync_blocks<<9;
1834                 }
1835
1836                 for (i=0 ; i < conf->raid_disks; i++) {
1837                         bio = r1_bio->bios[i];
1838                         if (bio->bi_end_io) {
1839                                 page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
1840                                 if (bio_add_page(bio, page, len, 0) == 0) {
1841                                         /* stop here */
1842                                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
1843                                         while (i > 0) {
1844                                                 i--;
1845                                                 bio = r1_bio->bios[i];
1846                                                 if (bio->bi_end_io==NULL)
1847                                                         continue;
1848                                                 /* remove last page from this bio */
1849                                                 bio->bi_vcnt--;
1850                                                 bio->bi_size -= len;
1851                                                 bio->bi_flags &= ~(1<< BIO_SEG_VALID);
1852                                         }
1853                                         goto bio_full;
1854                                 }
1855                         }
1856                 }
1857                 nr_sectors += len>>9;
1858                 sector_nr += len>>9;
1859                 sync_blocks -= (len>>9);
1860         } while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
1861  bio_full:
1862         r1_bio->sectors = nr_sectors;
1863
1864         /* For a user-requested sync, we read all readable devices and do a
1865          * compare
1866          */
1867         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1868                 atomic_set(&r1_bio->remaining, read_targets);
1869                 for (i=0; i<conf->raid_disks; i++) {
1870                         bio = r1_bio->bios[i];
1871                         if (bio->bi_end_io == end_sync_read) {
1872                                 md_sync_acct(bio->bi_bdev, nr_sectors);
1873                                 generic_make_request(bio);
1874                         }
1875                 }
1876         } else {
1877                 atomic_set(&r1_bio->remaining, 1);
1878                 bio = r1_bio->bios[r1_bio->read_disk];
1879                 md_sync_acct(bio->bi_bdev, nr_sectors);
1880                 generic_make_request(bio);
1881
1882         }
1883         return nr_sectors;
1884 }
1885
1886 static sector_t raid1_size(mddev_t *mddev, sector_t sectors, int raid_disks)
1887 {
1888         if (sectors)
1889                 return sectors;
1890
1891         return mddev->dev_sectors;
1892 }
1893
1894 static conf_t *setup_conf(mddev_t *mddev)
1895 {
1896         conf_t *conf;
1897         int i;
1898         mirror_info_t *disk;
1899         mdk_rdev_t *rdev;
1900         int err = -ENOMEM;
1901
1902         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
1903         if (!conf)
1904                 goto abort;
1905
1906         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
1907                                  GFP_KERNEL);
1908         if (!conf->mirrors)
1909                 goto abort;
1910
1911         conf->tmppage = alloc_page(GFP_KERNEL);
1912         if (!conf->tmppage)
1913                 goto abort;
1914
1915         conf->poolinfo = kzalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
1916         if (!conf->poolinfo)
1917                 goto abort;
1918         conf->poolinfo->raid_disks = mddev->raid_disks;
1919         conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
1920                                           r1bio_pool_free,
1921                                           conf->poolinfo);
1922         if (!conf->r1bio_pool)
1923                 goto abort;
1924
1925         conf->poolinfo->mddev = mddev;
1926
1927         spin_lock_init(&conf->device_lock);
1928         list_for_each_entry(rdev, &mddev->disks, same_set) {
1929                 int disk_idx = rdev->raid_disk;
1930                 if (disk_idx >= mddev->raid_disks
1931                     || disk_idx < 0)
1932                         continue;
1933                 disk = conf->mirrors + disk_idx;
1934
1935                 disk->rdev = rdev;
1936
1937                 disk->head_position = 0;
1938         }
1939         conf->raid_disks = mddev->raid_disks;
1940         conf->mddev = mddev;
1941         INIT_LIST_HEAD(&conf->retry_list);
1942
1943         spin_lock_init(&conf->resync_lock);
1944         init_waitqueue_head(&conf->wait_barrier);
1945
1946         bio_list_init(&conf->pending_bio_list);
1947
1948         conf->last_used = -1;
1949         for (i = 0; i < conf->raid_disks; i++) {
1950
1951                 disk = conf->mirrors + i;
1952
1953                 if (!disk->rdev ||
1954                     !test_bit(In_sync, &disk->rdev->flags)) {
1955                         disk->head_position = 0;
1956                         if (disk->rdev)
1957                                 conf->fullsync = 1;
1958                 } else if (conf->last_used < 0)
1959                         /*
1960                          * The first working device is used as a
1961                          * starting point to read balancing.
1962                          */
1963                         conf->last_used = i;
1964         }
1965
1966         err = -EIO;
1967         if (conf->last_used < 0) {
1968                 printk(KERN_ERR "md/raid1:%s: no operational mirrors\n",
1969                        mdname(mddev));
1970                 goto abort;
1971         }
1972         err = -ENOMEM;
1973         conf->thread = md_register_thread(raid1d, mddev, NULL);
1974         if (!conf->thread) {
1975                 printk(KERN_ERR
1976                        "md/raid1:%s: couldn't allocate thread\n",
1977                        mdname(mddev));
1978                 goto abort;
1979         }
1980
1981         return conf;
1982
1983  abort:
1984         if (conf) {
1985                 if (conf->r1bio_pool)
1986                         mempool_destroy(conf->r1bio_pool);
1987                 kfree(conf->mirrors);
1988                 safe_put_page(conf->tmppage);
1989                 kfree(conf->poolinfo);
1990                 kfree(conf);
1991         }
1992         return ERR_PTR(err);
1993 }
1994
1995 static int run(mddev_t *mddev)
1996 {
1997         conf_t *conf;
1998         int i;
1999         mdk_rdev_t *rdev;
2000
2001         if (mddev->level != 1) {
2002                 printk(KERN_ERR "md/raid1:%s: raid level not set to mirroring (%d)\n",
2003                        mdname(mddev), mddev->level);
2004                 return -EIO;
2005         }
2006         if (mddev->reshape_position != MaxSector) {
2007                 printk(KERN_ERR "md/raid1:%s: reshape_position set but not supported\n",
2008                        mdname(mddev));
2009                 return -EIO;
2010         }
2011         /*
2012          * copy the already verified devices into our private RAID1
2013          * bookkeeping area. [whatever we allocate in run(),
2014          * should be freed in stop()]
2015          */
2016         if (mddev->private == NULL)
2017                 conf = setup_conf(mddev);
2018         else
2019                 conf = mddev->private;
2020
2021         if (IS_ERR(conf))
2022                 return PTR_ERR(conf);
2023
2024         mddev->queue->queue_lock = &conf->device_lock;
2025         list_for_each_entry(rdev, &mddev->disks, same_set) {
2026                 disk_stack_limits(mddev->gendisk, rdev->bdev,
2027                                   rdev->data_offset << 9);
2028                 /* as we don't honour merge_bvec_fn, we must never risk
2029                  * violating it, so limit ->max_segments to 1 lying within
2030                  * a single page, as a one page request is never in violation.
2031                  */
2032                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
2033                         blk_queue_max_segments(mddev->queue, 1);
2034                         blk_queue_segment_boundary(mddev->queue,
2035                                                    PAGE_CACHE_SIZE - 1);
2036                 }
2037         }
2038
2039         mddev->degraded = 0;
2040         for (i=0; i < conf->raid_disks; i++)
2041                 if (conf->mirrors[i].rdev == NULL ||
2042                     !test_bit(In_sync, &conf->mirrors[i].rdev->flags) ||
2043                     test_bit(Faulty, &conf->mirrors[i].rdev->flags))
2044                         mddev->degraded++;
2045
2046         if (conf->raid_disks - mddev->degraded == 1)
2047                 mddev->recovery_cp = MaxSector;
2048
2049         if (mddev->recovery_cp != MaxSector)
2050                 printk(KERN_NOTICE "md/raid1:%s: not clean"
2051                        " -- starting background reconstruction\n",
2052                        mdname(mddev));
2053         printk(KERN_INFO
2054                 "md/raid1:%s: active with %d out of %d mirrors\n",
2055                 mdname(mddev), mddev->raid_disks - mddev->degraded,
2056                 mddev->raid_disks);
2057
2058         /*
2059          * Ok, everything is just fine now
2060          */
2061         mddev->thread = conf->thread;
2062         conf->thread = NULL;
2063         mddev->private = conf;
2064
2065         md_set_array_sectors(mddev, raid1_size(mddev, 0, 0));
2066
2067         mddev->queue->unplug_fn = raid1_unplug;
2068         mddev->queue->backing_dev_info.congested_fn = raid1_congested;
2069         mddev->queue->backing_dev_info.congested_data = mddev;
2070         md_integrity_register(mddev);
2071         return 0;
2072 }
2073
2074 static int stop(mddev_t *mddev)
2075 {
2076         conf_t *conf = mddev->private;
2077         struct bitmap *bitmap = mddev->bitmap;
2078
2079         /* wait for behind writes to complete */
2080         if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
2081                 printk(KERN_INFO "md/raid1:%s: behind writes in progress - waiting to stop.\n",
2082                        mdname(mddev));
2083                 /* need to kick something here to make sure I/O goes? */
2084                 wait_event(bitmap->behind_wait,
2085                            atomic_read(&bitmap->behind_writes) == 0);
2086         }
2087
2088         raise_barrier(conf);
2089         lower_barrier(conf);
2090
2091         md_unregister_thread(mddev->thread);
2092         mddev->thread = NULL;
2093         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2094         if (conf->r1bio_pool)
2095                 mempool_destroy(conf->r1bio_pool);
2096         kfree(conf->mirrors);
2097         kfree(conf->poolinfo);
2098         kfree(conf);
2099         mddev->private = NULL;
2100         return 0;
2101 }
2102
2103 static int raid1_resize(mddev_t *mddev, sector_t sectors)
2104 {
2105         /* no resync is happening, and there is enough space
2106          * on all devices, so we can resize.
2107          * We need to make sure resync covers any new space.
2108          * If the array is shrinking we should possibly wait until
2109          * any io in the removed space completes, but it hardly seems
2110          * worth it.
2111          */
2112         md_set_array_sectors(mddev, raid1_size(mddev, sectors, 0));
2113         if (mddev->array_sectors > raid1_size(mddev, sectors, 0))
2114                 return -EINVAL;
2115         set_capacity(mddev->gendisk, mddev->array_sectors);
2116         revalidate_disk(mddev->gendisk);
2117         if (sectors > mddev->dev_sectors &&
2118             mddev->recovery_cp == MaxSector) {
2119                 mddev->recovery_cp = mddev->dev_sectors;
2120                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2121         }
2122         mddev->dev_sectors = sectors;
2123         mddev->resync_max_sectors = sectors;
2124         return 0;
2125 }
2126
2127 static int raid1_reshape(mddev_t *mddev)
2128 {
2129         /* We need to:
2130          * 1/ resize the r1bio_pool
2131          * 2/ resize conf->mirrors
2132          *
2133          * We allocate a new r1bio_pool if we can.
2134          * Then raise a device barrier and wait until all IO stops.
2135          * Then resize conf->mirrors and swap in the new r1bio pool.
2136          *
2137          * At the same time, we "pack" the devices so that all the missing
2138          * devices have the higher raid_disk numbers.
2139          */
2140         mempool_t *newpool, *oldpool;
2141         struct pool_info *newpoolinfo;
2142         mirror_info_t *newmirrors;
2143         conf_t *conf = mddev->private;
2144         int cnt, raid_disks;
2145         unsigned long flags;
2146         int d, d2, err;
2147
2148         /* Cannot change chunk_size, layout, or level */
2149         if (mddev->chunk_sectors != mddev->new_chunk_sectors ||
2150             mddev->layout != mddev->new_layout ||
2151             mddev->level != mddev->new_level) {
2152                 mddev->new_chunk_sectors = mddev->chunk_sectors;
2153                 mddev->new_layout = mddev->layout;
2154                 mddev->new_level = mddev->level;
2155                 return -EINVAL;
2156         }
2157
2158         err = md_allow_write(mddev);
2159         if (err)
2160                 return err;
2161
2162         raid_disks = mddev->raid_disks + mddev->delta_disks;
2163
2164         if (raid_disks < conf->raid_disks) {
2165                 cnt=0;
2166                 for (d= 0; d < conf->raid_disks; d++)
2167                         if (conf->mirrors[d].rdev)
2168                                 cnt++;
2169                 if (cnt > raid_disks)
2170                         return -EBUSY;
2171         }
2172
2173         newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
2174         if (!newpoolinfo)
2175                 return -ENOMEM;
2176         newpoolinfo->mddev = mddev;
2177         newpoolinfo->raid_disks = raid_disks;
2178
2179         newpool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2180                                  r1bio_pool_free, newpoolinfo);
2181         if (!newpool) {
2182                 kfree(newpoolinfo);
2183                 return -ENOMEM;
2184         }
2185         newmirrors = kzalloc(sizeof(struct mirror_info) * raid_disks, GFP_KERNEL);
2186         if (!newmirrors) {
2187                 kfree(newpoolinfo);
2188                 mempool_destroy(newpool);
2189                 return -ENOMEM;
2190         }
2191
2192         raise_barrier(conf);
2193
2194         /* ok, everything is stopped */
2195         oldpool = conf->r1bio_pool;
2196         conf->r1bio_pool = newpool;
2197
2198         for (d = d2 = 0; d < conf->raid_disks; d++) {
2199                 mdk_rdev_t *rdev = conf->mirrors[d].rdev;
2200                 if (rdev && rdev->raid_disk != d2) {
2201                         char nm[20];
2202                         sprintf(nm, "rd%d", rdev->raid_disk);
2203                         sysfs_remove_link(&mddev->kobj, nm);
2204                         rdev->raid_disk = d2;
2205                         sprintf(nm, "rd%d", rdev->raid_disk);
2206                         sysfs_remove_link(&mddev->kobj, nm);
2207                         if (sysfs_create_link(&mddev->kobj,
2208                                               &rdev->kobj, nm))
2209                                 printk(KERN_WARNING
2210                                        "md/raid1:%s: cannot register "
2211                                        "%s\n",
2212                                        mdname(mddev), nm);
2213                 }
2214                 if (rdev)
2215                         newmirrors[d2++].rdev = rdev;
2216         }
2217         kfree(conf->mirrors);
2218         conf->mirrors = newmirrors;
2219         kfree(conf->poolinfo);
2220         conf->poolinfo = newpoolinfo;
2221
2222         spin_lock_irqsave(&conf->device_lock, flags);
2223         mddev->degraded += (raid_disks - conf->raid_disks);
2224         spin_unlock_irqrestore(&conf->device_lock, flags);
2225         conf->raid_disks = mddev->raid_disks = raid_disks;
2226         mddev->delta_disks = 0;
2227
2228         conf->last_used = 0; /* just make sure it is in-range */
2229         lower_barrier(conf);
2230
2231         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2232         md_wakeup_thread(mddev->thread);
2233
2234         mempool_destroy(oldpool);
2235         return 0;
2236 }
2237
2238 static void raid1_quiesce(mddev_t *mddev, int state)
2239 {
2240         conf_t *conf = mddev->private;
2241
2242         switch(state) {
2243         case 2: /* wake for suspend */
2244                 wake_up(&conf->wait_barrier);
2245                 break;
2246         case 1:
2247                 raise_barrier(conf);
2248                 break;
2249         case 0:
2250                 lower_barrier(conf);
2251                 break;
2252         }
2253 }
2254
2255 static void *raid1_takeover(mddev_t *mddev)
2256 {
2257         /* raid1 can take over:
2258          *  raid5 with 2 devices, any layout or chunk size
2259          */
2260         if (mddev->level == 5 && mddev->raid_disks == 2) {
2261                 conf_t *conf;
2262                 mddev->new_level = 1;
2263                 mddev->new_layout = 0;
2264                 mddev->new_chunk_sectors = 0;
2265                 conf = setup_conf(mddev);
2266                 if (!IS_ERR(conf))
2267                         conf->barrier = 1;
2268                 return conf;
2269         }
2270         return ERR_PTR(-EINVAL);
2271 }
2272
2273 static struct mdk_personality raid1_personality =
2274 {
2275         .name           = "raid1",
2276         .level          = 1,
2277         .owner          = THIS_MODULE,
2278         .make_request   = make_request,
2279         .run            = run,
2280         .stop           = stop,
2281         .status         = status,
2282         .error_handler  = error,
2283         .hot_add_disk   = raid1_add_disk,
2284         .hot_remove_disk= raid1_remove_disk,
2285         .spare_active   = raid1_spare_active,
2286         .sync_request   = sync_request,
2287         .resize         = raid1_resize,
2288         .size           = raid1_size,
2289         .check_reshape  = raid1_reshape,
2290         .quiesce        = raid1_quiesce,
2291         .takeover       = raid1_takeover,
2292 };
2293
2294 static int __init raid_init(void)
2295 {
2296         return register_md_personality(&raid1_personality);
2297 }
2298
2299 static void raid_exit(void)
2300 {
2301         unregister_md_personality(&raid1_personality);
2302 }
2303
2304 module_init(raid_init);
2305 module_exit(raid_exit);
2306 MODULE_LICENSE("GPL");
2307 MODULE_DESCRIPTION("RAID1 (mirroring) personality for MD");
2308 MODULE_ALIAS("md-personality-3"); /* RAID1 */
2309 MODULE_ALIAS("md-raid1");
2310 MODULE_ALIAS("md-level-1");