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 "dm-bio-list.h"
  35 #include <linux/delay.h>
  36 #include <linux/raid/raid1.h>
  37 #include <linux/raid/bitmap.h>
  38
  39 #define DEBUG 0
  40 #if DEBUG
  41 #define PRINTK(x...) printk(x)
  42 #else
  43 #define PRINTK(x...)
  44 #endif
  45
  46 /*
  47  * Number of guaranteed r1bios in case of extreme VM load:
  48  */
  49 #define NR_RAID1_BIOS 256
  50
  51
  52 static void unplug_slaves(mddev_t *mddev);
  53
  54 static void allow_barrier(conf_t *conf);
  55 static void lower_barrier(conf_t *conf);
  56
  57 static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
  58 {
  59         struct pool_info *pi = data;
  60         r1bio_t *r1_bio;
  61         int size = offsetof(r1bio_t, bios[pi->raid_disks]);
  62
  63         /* allocate a r1bio with room for raid_disks entries in the bios array */
  64         r1_bio = kzalloc(size, gfp_flags);
  65         if (!r1_bio)
  66                 unplug_slaves(pi->mddev);
  67
  68         return r1_bio;
  69 }
  70
  71 static void r1bio_pool_free(void *r1_bio, void *data)
  72 {
  73         kfree(r1_bio);
  74 }
  75
  76 #define RESYNC_BLOCK_SIZE (64*1024)
  77 //#define RESYNC_BLOCK_SIZE PAGE_SIZE
  78 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
  79 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
  80 #define RESYNC_WINDOW (2048*1024)
  81
  82 static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
  83 {
  84         struct pool_info *pi = data;
  85         struct page *page;
  86         r1bio_t *r1_bio;
  87         struct bio *bio;
  88         int i, j;
  89
  90         r1_bio = r1bio_pool_alloc(gfp_flags, pi);
  91         if (!r1_bio) {
  92                 unplug_slaves(pi->mddev);
  93                 return NULL;
  94         }
  95
  96         /*
  97          * Allocate bios : 1 for reading, n-1 for writing
  98          */
  99         for (j = pi->raid_disks ; j-- ; ) {
 100                 bio = bio_alloc(gfp_flags, RESYNC_PAGES);
 101                 if (!bio)
 102                         goto out_free_bio;
 103                 r1_bio->bios[j] = bio;
 104         }
 105         /*
 106          * Allocate RESYNC_PAGES data pages and attach them to
 107          * the first bio.
 108          * If this is a user-requested check/repair, allocate
 109          * RESYNC_PAGES for each bio.
 110          */
 111         if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
 112                 j = pi->raid_disks;
 113         else
 114                 j = 1;
 115         while(j--) {
 116                 bio = r1_bio->bios[j];
 117                 for (i = 0; i < RESYNC_PAGES; i++) {
 118                         page = alloc_page(gfp_flags);
 119                         if (unlikely(!page))
 120                                 goto out_free_pages;
 121
 122                         bio->bi_io_vec[i].bv_page = page;
 123                 }
 124         }
 125         /* If not user-requests, copy the page pointers to all bios */
 126         if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
 127                 for (i=0; i<RESYNC_PAGES ; i++)
 128                         for (j=1; j<pi->raid_disks; j++)
 129                                 r1_bio->bios[j]->bi_io_vec[i].bv_page =
 130                                         r1_bio->bios[0]->bi_io_vec[i].bv_page;
 131         }
 132
 133         r1_bio->master_bio = NULL;
 134
 135         return r1_bio;
 136
 137 out_free_pages:
 138         for (i=0; i < RESYNC_PAGES ; i++)
 139                 for (j=0 ; j < pi->raid_disks; j++)
 140                         safe_put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
 141         j = -1;
 142 out_free_bio:
 143         while ( ++j < pi->raid_disks )
 144                 bio_put(r1_bio->bios[j]);
 145         r1bio_pool_free(r1_bio, data);
 146         return NULL;
 147 }
 148
 149 static void r1buf_pool_free(void *__r1_bio, void *data)
 150 {
 151         struct pool_info *pi = data;
 152         int i,j;
 153         r1bio_t *r1bio = __r1_bio;
 154
 155         for (i = 0; i < RESYNC_PAGES; i++)
 156                 for (j = pi->raid_disks; j-- ;) {
 157                         if (j == 0 ||
 158                             r1bio->bios[j]->bi_io_vec[i].bv_page !=
 159                             r1bio->bios[0]->bi_io_vec[i].bv_page)
 160                                 safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
 161                 }
 162         for (i=0 ; i < pi->raid_disks; i++)
 163                 bio_put(r1bio->bios[i]);
 164
 165         r1bio_pool_free(r1bio, data);
 166 }
 167
 168 static void put_all_bios(conf_t *conf, r1bio_t *r1_bio)
 169 {
 170         int i;
 171
 172         for (i = 0; i < conf->raid_disks; i++) {
 173                 struct bio **bio = r1_bio->bios + i;
 174                 if (*bio && *bio != IO_BLOCKED)
 175                         bio_put(*bio);
 176                 *bio = NULL;
 177         }
 178 }
 179
 180 static void free_r1bio(r1bio_t *r1_bio)
 181 {
 182         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 183
 184         /*
 185          * Wake up any possible resync thread that waits for the device
 186          * to go idle.
 187          */
 188         allow_barrier(conf);
 189
 190         put_all_bios(conf, r1_bio);
 191         mempool_free(r1_bio, conf->r1bio_pool);
 192 }
 193
 194 static void put_buf(r1bio_t *r1_bio)
 195 {
 196         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 197         int i;
 198
 199         for (i=0; i<conf->raid_disks; i++) {
 200                 struct bio *bio = r1_bio->bios[i];
 201                 if (bio->bi_end_io)
 202                         rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
 203         }
 204
 205         mempool_free(r1_bio, conf->r1buf_pool);
 206
 207         lower_barrier(conf);
 208 }
 209
 210 static void reschedule_retry(r1bio_t *r1_bio)
 211 {
 212         unsigned long flags;
 213         mddev_t *mddev = r1_bio->mddev;
 214         conf_t *conf = mddev_to_conf(mddev);
 215
 216         spin_lock_irqsave(&conf->device_lock, flags);
 217         list_add(&r1_bio->retry_list, &conf->retry_list);
 218         conf->nr_queued ++;
 219         spin_unlock_irqrestore(&conf->device_lock, flags);
 220
 221         wake_up(&conf->wait_barrier);
 222         md_wakeup_thread(mddev->thread);
 223 }
 224
 225 /*
 226  * raid_end_bio_io() is called when we have finished servicing a mirrored
 227  * operation and are ready to return a success/failure code to the buffer
 228  * cache layer.
 229  */
 230 static void raid_end_bio_io(r1bio_t *r1_bio)
 231 {
 232         struct bio *bio = r1_bio->master_bio;
 233
 234         /* if nobody has done the final endio yet, do it now */
 235         if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 236                 PRINTK(KERN_DEBUG "raid1: sync end %s on sectors %llu-%llu\n",
 237                         (bio_data_dir(bio) == WRITE) ? "write" : "read",
 238                         (unsigned long long) bio->bi_sector,
 239                         (unsigned long long) bio->bi_sector +
 240                                 (bio->bi_size >> 9) - 1);
 241
 242                 bio_endio(bio,
 243                         test_bit(R1BIO_Uptodate, &r1_bio->state) ? 0 : -EIO);
 244         }
 245         free_r1bio(r1_bio);
 246 }
 247
 248 /*
 249  * Update disk head position estimator based on IRQ completion info.
 250  */
 251 static inline void update_head_pos(int disk, r1bio_t *r1_bio)
 252 {
 253         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 254
 255         conf->mirrors[disk].head_position =
 256                 r1_bio->sector + (r1_bio->sectors);
 257 }
 258
 259 static void raid1_end_read_request(struct bio *bio, int error)
 260 {
 261         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 262         r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
 263         int mirror;
 264         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 265
 266         mirror = r1_bio->read_disk;
 267         /*
 268          * this branch is our 'one mirror IO has finished' event handler:
 269          */
 270         update_head_pos(mirror, r1_bio);
 271
 272         if (uptodate)
 273                 set_bit(R1BIO_Uptodate, &r1_bio->state);
 274         else {
 275                 /* If all other devices have failed, we want to return
 276                  * the error upwards rather than fail the last device.
 277                  * Here we redefine "uptodate" to mean "Don't want to retry"
 278                  */
 279                 unsigned long flags;
 280                 spin_lock_irqsave(&conf->device_lock, flags);
 281                 if (r1_bio->mddev->degraded == conf->raid_disks ||
 282                     (r1_bio->mddev->degraded == conf->raid_disks-1 &&
 283                      !test_bit(Faulty, &conf->mirrors[mirror].rdev->flags)))
 284                         uptodate = 1;
 285                 spin_unlock_irqrestore(&conf->device_lock, flags);
 286         }
 287
 288         if (uptodate)
 289                 raid_end_bio_io(r1_bio);
 290         else {
 291                 /*
 292                  * oops, read error:
 293                  */
 294                 char b[BDEVNAME_SIZE];
 295                 if (printk_ratelimit())
 296                         printk(KERN_ERR "raid1: %s: rescheduling sector %llu\n",
 297                                bdevname(conf->mirrors[mirror].rdev->bdev,b), (unsigned long long)r1_bio->sector);
 298                 reschedule_retry(r1_bio);
 299         }
 300
 301         rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 302 }
 303
 304 static void raid1_end_write_request(struct bio *bio, int error)
 305 {
 306         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 307         r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
 308         int mirror, behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
 309         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 310         struct bio *to_put = NULL;
 311
 312
 313         for (mirror = 0; mirror < conf->raid_disks; mirror++)
 314                 if (r1_bio->bios[mirror] == bio)
 315                         break;
 316
 317         if (error == -EOPNOTSUPP && test_bit(R1BIO_Barrier, &r1_bio->state)) {
 318                 set_bit(BarriersNotsupp, &conf->mirrors[mirror].rdev->flags);
 319                 set_bit(R1BIO_BarrierRetry, &r1_bio->state);
 320                 r1_bio->mddev->barriers_work = 0;
 321                 /* Don't rdev_dec_pending in this branch - keep it for the retry */
 322         } else {
 323                 /*
 324                  * this branch is our 'one mirror IO has finished' event handler:
 325                  */
 326                 r1_bio->bios[mirror] = NULL;
 327                 to_put = bio;
 328                 if (!uptodate) {
 329                         md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
 330                         /* an I/O failed, we can't clear the bitmap */
 331                         set_bit(R1BIO_Degraded, &r1_bio->state);
 332                 } else
 333                         /*
 334                          * Set R1BIO_Uptodate in our master bio, so that
 335                          * we will return a good error code for to the higher
 336                          * levels even if IO on some other mirrored buffer fails.
 337                          *
 338                          * The 'master' represents the composite IO operation to
 339                          * user-side. So if something waits for IO, then it will
 340                          * wait for the 'master' bio.
 341                          */
 342                         set_bit(R1BIO_Uptodate, &r1_bio->state);
 343
 344                 update_head_pos(mirror, r1_bio);
 345
 346                 if (behind) {
 347                         if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
 348                                 atomic_dec(&r1_bio->behind_remaining);
 349
 350                         /* In behind mode, we ACK the master bio once the I/O has safely
 351                          * reached all non-writemostly disks. Setting the Returned bit
 352                          * ensures that this gets done only once -- we don't ever want to
 353                          * return -EIO here, instead we'll wait */
 354
 355                         if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
 356                             test_bit(R1BIO_Uptodate, &r1_bio->state)) {
 357                                 /* Maybe we can return now */
 358                                 if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 359                                         struct bio *mbio = r1_bio->master_bio;
 360                                         PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
 361                                                (unsigned long long) mbio->bi_sector,
 362                                                (unsigned long long) mbio->bi_sector +
 363                                                (mbio->bi_size >> 9) - 1);
 364                                         bio_endio(mbio, 0);
 365                                 }
 366                         }
 367                 }
 368                 rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 369         }
 370         /*
 371          *
 372          * Let's see if all mirrored write operations have finished
 373          * already.
 374          */
 375         if (atomic_dec_and_test(&r1_bio->remaining)) {
 376                 if (test_bit(R1BIO_BarrierRetry, &r1_bio->state))
 377                         reschedule_retry(r1_bio);
 378                 else {
 379                         /* it really is the end of this request */
 380                         if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
 381                                 /* free extra copy of the data pages */
 382                                 int i = bio->bi_vcnt;
 383                                 while (i--)
 384                                         safe_put_page(bio->bi_io_vec[i].bv_page);
 385                         }
 386                         /* clear the bitmap if all writes complete successfully */
 387                         bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
 388                                         r1_bio->sectors,
 389                                         !test_bit(R1BIO_Degraded, &r1_bio->state),
 390                                         behind);
 391                         md_write_end(r1_bio->mddev);
 392                         raid_end_bio_io(r1_bio);
 393                 }
 394         }
 395
 396         if (to_put)
 397                 bio_put(to_put);
 398 }
 399
 400
 401 /*
 402  * This routine returns the disk from which the requested read should
 403  * be done. There is a per-array 'next expected sequential IO' sector
 404  * number - if this matches on the next IO then we use the last disk.
 405  * There is also a per-disk 'last know head position' sector that is
 406  * maintained from IRQ contexts, both the normal and the resync IO
 407  * completion handlers update this position correctly. If there is no
 408  * perfect sequential match then we pick the disk whose head is closest.
 409  *
 410  * If there are 2 mirrors in the same 2 devices, performance degrades
 411  * because position is mirror, not device based.
 412  *
 413  * The rdev for the device selected will have nr_pending incremented.
 414  */
 415 static int read_balance(conf_t *conf, r1bio_t *r1_bio)
 416 {
 417         const unsigned long this_sector = r1_bio->sector;
 418         int new_disk = conf->last_used, disk = new_disk;
 419         int wonly_disk = -1;
 420         const int sectors = r1_bio->sectors;
 421         sector_t new_distance, current_distance;
 422         mdk_rdev_t *rdev;
 423
 424         rcu_read_lock();
 425         /*
 426          * Check if we can balance. We can balance on the whole
 427          * device if no resync is going on, or below the resync window.
 428          * We take the first readable disk when above the resync window.
 429          */
 430  retry:
 431         if (conf->mddev->recovery_cp < MaxSector &&
 432             (this_sector + sectors >= conf->next_resync)) {
 433                 /* Choose the first operation device, for consistancy */
 434                 new_disk = 0;
 435
 436                 for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 437                      r1_bio->bios[new_disk] == IO_BLOCKED ||
 438                      !rdev || !test_bit(In_sync, &rdev->flags)
 439                              || test_bit(WriteMostly, &rdev->flags);
 440                      rdev = rcu_dereference(conf->mirrors[++new_disk].rdev)) {
 441
 442                         if (rdev && test_bit(In_sync, &rdev->flags) &&
 443                                 r1_bio->bios[new_disk] != IO_BLOCKED)
 444                                 wonly_disk = new_disk;
 445
 446                         if (new_disk == conf->raid_disks - 1) {
 447                                 new_disk = wonly_disk;
 448                                 break;
 449                         }
 450                 }
 451                 goto rb_out;
 452         }
 453
 454
 455         /* make sure the disk is operational */
 456         for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 457              r1_bio->bios[new_disk] == IO_BLOCKED ||
 458              !rdev || !test_bit(In_sync, &rdev->flags) ||
 459                      test_bit(WriteMostly, &rdev->flags);
 460              rdev = rcu_dereference(conf->mirrors[new_disk].rdev)) {
 461
 462                 if (rdev && test_bit(In_sync, &rdev->flags) &&
 463                     r1_bio->bios[new_disk] != IO_BLOCKED)
 464                         wonly_disk = new_disk;
 465
 466                 if (new_disk <= 0)
 467                         new_disk = conf->raid_disks;
 468                 new_disk--;
 469                 if (new_disk == disk) {
 470                         new_disk = wonly_disk;
 471                         break;
 472                 }
 473         }
 474
 475         if (new_disk < 0)
 476                 goto rb_out;
 477
 478         disk = new_disk;
 479         /* now disk == new_disk == starting point for search */
 480
 481         /*
 482          * Don't change to another disk for sequential reads:
 483          */
 484         if (conf->next_seq_sect == this_sector)
 485                 goto rb_out;
 486         if (this_sector == conf->mirrors[new_disk].head_position)
 487                 goto rb_out;
 488
 489         current_distance = abs(this_sector - conf->mirrors[disk].head_position);
 490
 491         /* Find the disk whose head is closest */
 492
 493         do {
 494                 if (disk <= 0)
 495                         disk = conf->raid_disks;
 496                 disk--;
 497
 498                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 499
 500                 if (!rdev || r1_bio->bios[disk] == IO_BLOCKED ||
 501                     !test_bit(In_sync, &rdev->flags) ||
 502                     test_bit(WriteMostly, &rdev->flags))
 503                         continue;
 504
 505                 if (!atomic_read(&rdev->nr_pending)) {
 506                         new_disk = disk;
 507                         break;
 508                 }
 509                 new_distance = abs(this_sector - conf->mirrors[disk].head_position);
 510                 if (new_distance < current_distance) {
 511                         current_distance = new_distance;
 512                         new_disk = disk;
 513                 }
 514         } while (disk != conf->last_used);
 515
 516  rb_out:
 517
 518
 519         if (new_disk >= 0) {
 520                 rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 521                 if (!rdev)
 522                         goto retry;
 523                 atomic_inc(&rdev->nr_pending);
 524                 if (!test_bit(In_sync, &rdev->flags)) {
 525                         /* cannot risk returning a device that failed
 526                          * before we inc'ed nr_pending
 527                          */
 528                         rdev_dec_pending(rdev, conf->mddev);
 529                         goto retry;
 530                 }
 531                 conf->next_seq_sect = this_sector + sectors;
 532                 conf->last_used = new_disk;
 533         }
 534         rcu_read_unlock();
 535
 536         return new_disk;
 537 }
 538
 539 static void unplug_slaves(mddev_t *mddev)
 540 {
 541         conf_t *conf = mddev_to_conf(mddev);
 542         int i;
 543
 544         rcu_read_lock();
 545         for (i=0; i<mddev->raid_disks; i++) {
 546                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 547                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
 548                         struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
 549
 550                         atomic_inc(&rdev->nr_pending);
 551                         rcu_read_unlock();
 552
 553                         blk_unplug(r_queue);
 554
 555                         rdev_dec_pending(rdev, mddev);
 556                         rcu_read_lock();
 557                 }
 558         }
 559         rcu_read_unlock();
 560 }
 561
 562 static void raid1_unplug(struct request_queue *q)
 563 {
 564         mddev_t *mddev = q->queuedata;
 565
 566         unplug_slaves(mddev);
 567         md_wakeup_thread(mddev->thread);
 568 }
 569
 570 static int raid1_congested(void *data, int bits)
 571 {
 572         mddev_t *mddev = data;
 573         conf_t *conf = mddev_to_conf(mddev);
 574         int i, ret = 0;
 575
 576         rcu_read_lock();
 577         for (i = 0; i < mddev->raid_disks; i++) {
 578                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 579                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 580                         struct request_queue *q = bdev_get_queue(rdev->bdev);
 581
 582                         /* Note the '|| 1' - when read_balance prefers
 583                          * non-congested targets, it can be removed
 584                          */
 585                         if ((bits & (1<<BDI_write_congested)) || 1)
 586                                 ret |= bdi_congested(&q->backing_dev_info, bits);
 587                         else
 588                                 ret &= bdi_congested(&q->backing_dev_info, bits);
 589                 }
 590         }
 591         rcu_read_unlock();
 592         return ret;
 593 }
 594
 595
 596 static int flush_pending_writes(conf_t *conf)
 597 {
 598         /* Any writes that have been queued but are awaiting
 599          * bitmap updates get flushed here.
 600          * We return 1 if any requests were actually submitted.
 601          */
 602         int rv = 0;
 603
 604         spin_lock_irq(&conf->device_lock);
 605
 606         if (conf->pending_bio_list.head) {
 607                 struct bio *bio;
 608                 bio = bio_list_get(&conf->pending_bio_list);
 609                 blk_remove_plug(conf->mddev->queue);
 610                 spin_unlock_irq(&conf->device_lock);
 611                 /* flush any pending bitmap writes to
 612                  * disk before proceeding w/ I/O */
 613                 bitmap_unplug(conf->mddev->bitmap);
 614
 615                 while (bio) { /* submit pending writes */
 616                         struct bio *next = bio->bi_next;
 617                         bio->bi_next = NULL;
 618                         generic_make_request(bio);
 619                         bio = next;
 620                 }
 621                 rv = 1;
 622         } else
 623                 spin_unlock_irq(&conf->device_lock);
 624         return rv;
 625 }
 626
 627 /* Barriers....
 628  * Sometimes we need to suspend IO while we do something else,
 629  * either some resync/recovery, or reconfigure the array.
 630  * To do this we raise a 'barrier'.
 631  * The 'barrier' is a counter that can be raised multiple times
 632  * to count how many activities are happening which preclude
 633  * normal IO.
 634  * We can only raise the barrier if there is no pending IO.
 635  * i.e. if nr_pending == 0.
 636  * We choose only to raise the barrier if no-one is waiting for the
 637  * barrier to go down.  This means that as soon as an IO request
 638  * is ready, no other operations which require a barrier will start
 639  * until the IO request has had a chance.
 640  *
 641  * So: regular IO calls 'wait_barrier'.  When that returns there
 642  *    is no backgroup IO happening,  It must arrange to call
 643  *    allow_barrier when it has finished its IO.
 644  * backgroup IO calls must call raise_barrier.  Once that returns
 645  *    there is no normal IO happeing.  It must arrange to call
 646  *    lower_barrier when the particular background IO completes.
 647  */
 648 #define RESYNC_DEPTH 32
 649
 650 static void raise_barrier(conf_t *conf)
 651 {
 652         spin_lock_irq(&conf->resync_lock);
 653
 654         /* Wait until no block IO is waiting */
 655         wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
 656                             conf->resync_lock,
 657                             raid1_unplug(conf->mddev->queue));
 658
 659         /* block any new IO from starting */
 660         conf->barrier++;
 661
 662         /* No wait for all pending IO to complete */
 663         wait_event_lock_irq(conf->wait_barrier,
 664                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 665                             conf->resync_lock,
 666                             raid1_unplug(conf->mddev->queue));
 667
 668         spin_unlock_irq(&conf->resync_lock);
 669 }
 670
 671 static void lower_barrier(conf_t *conf)
 672 {
 673         unsigned long flags;
 674         spin_lock_irqsave(&conf->resync_lock, flags);
 675         conf->barrier--;
 676         spin_unlock_irqrestore(&conf->resync_lock, flags);
 677         wake_up(&conf->wait_barrier);
 678 }
 679
 680 static void wait_barrier(conf_t *conf)
 681 {
 682         spin_lock_irq(&conf->resync_lock);
 683         if (conf->barrier) {
 684                 conf->nr_waiting++;
 685                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
 686                                     conf->resync_lock,
 687                                     raid1_unplug(conf->mddev->queue));
 688                 conf->nr_waiting--;
 689         }
 690         conf->nr_pending++;
 691         spin_unlock_irq(&conf->resync_lock);
 692 }
 693
 694 static void allow_barrier(conf_t *conf)
 695 {
 696         unsigned long flags;
 697         spin_lock_irqsave(&conf->resync_lock, flags);
 698         conf->nr_pending--;
 699         spin_unlock_irqrestore(&conf->resync_lock, flags);
 700         wake_up(&conf->wait_barrier);
 701 }
 702
 703 static void freeze_array(conf_t *conf)
 704 {
 705         /* stop syncio and normal IO and wait for everything to
 706          * go quite.
 707          * We increment barrier and nr_waiting, and then
 708          * wait until nr_pending match nr_queued+1
 709          * This is called in the context of one normal IO request
 710          * that has failed. Thus any sync request that might be pending
 711          * will be blocked by nr_pending, and we need to wait for
 712          * pending IO requests to complete or be queued for re-try.
 713          * Thus the number queued (nr_queued) plus this request (1)
 714          * must match the number of pending IOs (nr_pending) before
 715          * we continue.
 716          */
 717         spin_lock_irq(&conf->resync_lock);
 718         conf->barrier++;
 719         conf->nr_waiting++;
 720         wait_event_lock_irq(conf->wait_barrier,
 721                             conf->nr_pending == conf->nr_queued+1,
 722                             conf->resync_lock,
 723                             ({ flush_pending_writes(conf);
 724                                raid1_unplug(conf->mddev->queue); }));
 725         spin_unlock_irq(&conf->resync_lock);
 726 }
 727 static void unfreeze_array(conf_t *conf)
 728 {
 729         /* reverse the effect of the freeze */
 730         spin_lock_irq(&conf->resync_lock);
 731         conf->barrier--;
 732         conf->nr_waiting--;
 733         wake_up(&conf->wait_barrier);
 734         spin_unlock_irq(&conf->resync_lock);
 735 }
 736
 737
 738 /* duplicate the data pages for behind I/O */
 739 static struct page **alloc_behind_pages(struct bio *bio)
 740 {
 741         int i;
 742         struct bio_vec *bvec;
 743         struct page **pages = kzalloc(bio->bi_vcnt * sizeof(struct page *),
 744                                         GFP_NOIO);
 745         if (unlikely(!pages))
 746                 goto do_sync_io;
 747
 748         bio_for_each_segment(bvec, bio, i) {
 749                 pages[i] = alloc_page(GFP_NOIO);
 750                 if (unlikely(!pages[i]))
 751                         goto do_sync_io;
 752                 memcpy(kmap(pages[i]) + bvec->bv_offset,
 753                         kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
 754                 kunmap(pages[i]);
 755                 kunmap(bvec->bv_page);
 756         }
 757
 758         return pages;
 759
 760 do_sync_io:
 761         if (pages)
 762                 for (i = 0; i < bio->bi_vcnt && pages[i]; i++)
 763                         put_page(pages[i]);
 764         kfree(pages);
 765         PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
 766         return NULL;
 767 }
 768
 769 static int make_request(struct request_queue *q, struct bio * bio)
 770 {
 771         mddev_t *mddev = q->queuedata;
 772         conf_t *conf = mddev_to_conf(mddev);
 773         mirror_info_t *mirror;
 774         r1bio_t *r1_bio;
 775         struct bio *read_bio;
 776         int i, targets = 0, disks;
 777         struct bitmap *bitmap;
 778         unsigned long flags;
 779         struct bio_list bl;
 780         struct page **behind_pages = NULL;
 781         const int rw = bio_data_dir(bio);
 782         const int do_sync = bio_sync(bio);
 783         int cpu, do_barriers;
 784         mdk_rdev_t *blocked_rdev;
 785
 786         /*
 787          * Register the new request and wait if the reconstruction
 788          * thread has put up a bar for new requests.
 789          * Continue immediately if no resync is active currently.
 790          * We test barriers_work *after* md_write_start as md_write_start
 791          * may cause the first superblock write, and that will check out
 792          * if barriers work.
 793          */
 794
 795         md_write_start(mddev, bio); /* wait on superblock update early */
 796
 797         if (unlikely(!mddev->barriers_work && bio_barrier(bio))) {
 798                 if (rw == WRITE)
 799                         md_write_end(mddev);
 800                 bio_endio(bio, -EOPNOTSUPP);
 801                 return 0;
 802         }
 803
 804         wait_barrier(conf);
 805
 806         bitmap = mddev->bitmap;
 807
 808         cpu = part_stat_lock();
 809         part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
 810         part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
 811                       bio_sectors(bio));
 812         part_stat_unlock();
 813
 814         /*
 815          * make_request() can abort the operation when READA is being
 816          * used and no empty request is available.
 817          *
 818          */
 819         r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
 820
 821         r1_bio->master_bio = bio;
 822         r1_bio->sectors = bio->bi_size >> 9;
 823         r1_bio->state = 0;
 824         r1_bio->mddev = mddev;
 825         r1_bio->sector = bio->bi_sector;
 826
 827         if (rw == READ) {
 828                 /*
 829                  * read balancing logic:
 830                  */
 831                 int rdisk = read_balance(conf, r1_bio);
 832
 833                 if (rdisk < 0) {
 834                         /* couldn't find anywhere to read from */
 835                         raid_end_bio_io(r1_bio);
 836                         return 0;
 837                 }
 838                 mirror = conf->mirrors + rdisk;
 839
 840                 r1_bio->read_disk = rdisk;
 841
 842                 read_bio = bio_clone(bio, GFP_NOIO);
 843
 844                 r1_bio->bios[rdisk] = read_bio;
 845
 846                 read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
 847                 read_bio->bi_bdev = mirror->rdev->bdev;
 848                 read_bio->bi_end_io = raid1_end_read_request;
 849                 read_bio->bi_rw = READ | do_sync;
 850                 read_bio->bi_private = r1_bio;
 851
 852                 generic_make_request(read_bio);
 853                 return 0;
 854         }
 855
 856         /*
 857          * WRITE:
 858          */
 859         /* first select target devices under spinlock and
 860          * inc refcount on their rdev.  Record them by setting
 861          * bios[x] to bio
 862          */
 863         disks = conf->raid_disks;
 864 #if 0
 865         { static int first=1;
 866         if (first) printk("First Write sector %llu disks %d\n",
 867                           (unsigned long long)r1_bio->sector, disks);
 868         first = 0;
 869         }
 870 #endif
 871  retry_write:
 872         blocked_rdev = NULL;
 873         rcu_read_lock();
 874         for (i = 0;  i < disks; i++) {
 875                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 876                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
 877                         atomic_inc(&rdev->nr_pending);
 878                         blocked_rdev = rdev;
 879                         break;
 880                 }
 881                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 882                         atomic_inc(&rdev->nr_pending);
 883                         if (test_bit(Faulty, &rdev->flags)) {
 884                                 rdev_dec_pending(rdev, mddev);
 885                                 r1_bio->bios[i] = NULL;
 886                         } else
 887                                 r1_bio->bios[i] = bio;
 888                         targets++;
 889                 } else
 890                         r1_bio->bios[i] = NULL;
 891         }
 892         rcu_read_unlock();
 893
 894         if (unlikely(blocked_rdev)) {
 895                 /* Wait for this device to become unblocked */
 896                 int j;
 897
 898                 for (j = 0; j < i; j++)
 899                         if (r1_bio->bios[j])
 900                                 rdev_dec_pending(conf->mirrors[j].rdev, mddev);
 901
 902                 allow_barrier(conf);
 903                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
 904                 wait_barrier(conf);
 905                 goto retry_write;
 906         }
 907
 908         BUG_ON(targets == 0); /* we never fail the last device */
 909
 910         if (targets < conf->raid_disks) {
 911                 /* array is degraded, we will not clear the bitmap
 912                  * on I/O completion (see raid1_end_write_request) */
 913                 set_bit(R1BIO_Degraded, &r1_bio->state);
 914         }
 915
 916         /* do behind I/O ? */
 917         if (bitmap &&
 918             atomic_read(&bitmap->behind_writes) < bitmap->max_write_behind &&
 919             (behind_pages = alloc_behind_pages(bio)) != NULL)
 920                 set_bit(R1BIO_BehindIO, &r1_bio->state);
 921
 922         atomic_set(&r1_bio->remaining, 0);
 923         atomic_set(&r1_bio->behind_remaining, 0);
 924
 925         do_barriers = bio_barrier(bio);
 926         if (do_barriers)
 927                 set_bit(R1BIO_Barrier, &r1_bio->state);
 928
 929         bio_list_init(&bl);
 930         for (i = 0; i < disks; i++) {
 931                 struct bio *mbio;
 932                 if (!r1_bio->bios[i])
 933                         continue;
 934
 935                 mbio = bio_clone(bio, GFP_NOIO);
 936                 r1_bio->bios[i] = mbio;
 937
 938                 mbio->bi_sector = r1_bio->sector + conf->mirrors[i].rdev->data_offset;
 939                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
 940                 mbio->bi_end_io = raid1_end_write_request;
 941                 mbio->bi_rw = WRITE | do_barriers | do_sync;
 942                 mbio->bi_private = r1_bio;
 943
 944                 if (behind_pages) {
 945                         struct bio_vec *bvec;
 946                         int j;
 947
 948                         /* Yes, I really want the '__' version so that
 949                          * we clear any unused pointer in the io_vec, rather
 950                          * than leave them unchanged.  This is important
 951                          * because when we come to free the pages, we won't
 952                          * know the originial bi_idx, so we just free
 953                          * them all
 954                          */
 955                         __bio_for_each_segment(bvec, mbio, j, 0)
 956                                 bvec->bv_page = behind_pages[j];
 957                         if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
 958                                 atomic_inc(&r1_bio->behind_remaining);
 959                 }
 960
 961                 atomic_inc(&r1_bio->remaining);
 962
 963                 bio_list_add(&bl, mbio);
 964         }
 965         kfree(behind_pages); /* the behind pages are attached to the bios now */
 966
 967         bitmap_startwrite(bitmap, bio->bi_sector, r1_bio->sectors,
 968                                 test_bit(R1BIO_BehindIO, &r1_bio->state));
 969         spin_lock_irqsave(&conf->device_lock, flags);
 970         bio_list_merge(&conf->pending_bio_list, &bl);
 971         bio_list_init(&bl);
 972
 973         blk_plug_device(mddev->queue);
 974         spin_unlock_irqrestore(&conf->device_lock, flags);
 975
 976         /* In case raid1d snuck into freeze_array */
 977         wake_up(&conf->wait_barrier);
 978
 979         if (do_sync)
 980                 md_wakeup_thread(mddev->thread);
 981 #if 0
 982         while ((bio = bio_list_pop(&bl)) != NULL)
 983                 generic_make_request(bio);
 984 #endif
 985
 986         return 0;
 987 }
 988
 989 static void status(struct seq_file *seq, mddev_t *mddev)
 990 {
 991         conf_t *conf = mddev_to_conf(mddev);
 992         int i;
 993
 994         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 995                    conf->raid_disks - mddev->degraded);
 996         rcu_read_lock();
 997         for (i = 0; i < conf->raid_disks; i++) {
 998                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 999                 seq_printf(seq, "%s",
1000                            rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
1001         }
1002         rcu_read_unlock();
1003         seq_printf(seq, "]");
1004 }
1005
1006
1007 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1008 {
1009         char b[BDEVNAME_SIZE];
1010         conf_t *conf = mddev_to_conf(mddev);
1011
1012         /*
1013          * If it is not operational, then we have already marked it as dead
1014          * else if it is the last working disks, ignore the error, let the
1015          * next level up know.
1016          * else mark the drive as failed
1017          */
1018         if (test_bit(In_sync, &rdev->flags)
1019             && (conf->raid_disks - mddev->degraded) == 1) {
1020                 /*
1021                  * Don't fail the drive, act as though we were just a
1022                  * normal single drive.
1023                  * However don't try a recovery from this drive as
1024                  * it is very likely to fail.
1025                  */
1026                 mddev->recovery_disabled = 1;
1027                 return;
1028         }
1029         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1030                 unsigned long flags;
1031                 spin_lock_irqsave(&conf->device_lock, flags);
1032                 mddev->degraded++;
1033                 set_bit(Faulty, &rdev->flags);
1034                 spin_unlock_irqrestore(&conf->device_lock, flags);
1035                 /*
1036                  * if recovery is running, make sure it aborts.
1037                  */
1038                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1039         } else
1040                 set_bit(Faulty, &rdev->flags);
1041         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1042         printk(KERN_ALERT "raid1: Disk failure on %s, disabling device.\n"
1043                 "raid1: Operation continuing on %d devices.\n",
1044                 bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
1045 }
1046
1047 static void print_conf(conf_t *conf)
1048 {
1049         int i;
1050
1051         printk("RAID1 conf printout:\n");
1052         if (!conf) {
1053                 printk("(!conf)\n");
1054                 return;
1055         }
1056         printk(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1057                 conf->raid_disks);
1058
1059         rcu_read_lock();
1060         for (i = 0; i < conf->raid_disks; i++) {
1061                 char b[BDEVNAME_SIZE];
1062                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
1063                 if (rdev)
1064                         printk(" disk %d, wo:%d, o:%d, dev:%s\n",
1065                                i, !test_bit(In_sync, &rdev->flags),
1066                                !test_bit(Faulty, &rdev->flags),
1067                                bdevname(rdev->bdev,b));
1068         }
1069         rcu_read_unlock();
1070 }
1071
1072 static void close_sync(conf_t *conf)
1073 {
1074         wait_barrier(conf);
1075         allow_barrier(conf);
1076
1077         mempool_destroy(conf->r1buf_pool);
1078         conf->r1buf_pool = NULL;
1079 }
1080
1081 static int raid1_spare_active(mddev_t *mddev)
1082 {
1083         int i;
1084         conf_t *conf = mddev->private;
1085
1086         /*
1087          * Find all failed disks within the RAID1 configuration
1088          * and mark them readable.
1089          * Called under mddev lock, so rcu protection not needed.
1090          */
1091         for (i = 0; i < conf->raid_disks; i++) {
1092                 mdk_rdev_t *rdev = conf->mirrors[i].rdev;
1093                 if (rdev
1094                     && !test_bit(Faulty, &rdev->flags)
1095                     && !test_and_set_bit(In_sync, &rdev->flags)) {
1096                         unsigned long flags;
1097                         spin_lock_irqsave(&conf->device_lock, flags);
1098                         mddev->degraded--;
1099                         spin_unlock_irqrestore(&conf->device_lock, flags);
1100                 }
1101         }
1102
1103         print_conf(conf);
1104         return 0;
1105 }
1106
1107
1108 static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1109 {
1110         conf_t *conf = mddev->private;
1111         int err = -EEXIST;
1112         int mirror = 0;
1113         mirror_info_t *p;
1114         int first = 0;
1115         int last = mddev->raid_disks - 1;
1116
1117         if (rdev->raid_disk >= 0)
1118                 first = last = rdev->raid_disk;
1119
1120         for (mirror = first; mirror <= last; mirror++)
1121                 if ( !(p=conf->mirrors+mirror)->rdev) {
1122
1123                         blk_queue_stack_limits(mddev->queue,
1124                                                rdev->bdev->bd_disk->queue);
1125                         /* as we don't honour merge_bvec_fn, we must never risk
1126                          * violating it, so limit ->max_sector to one PAGE, as
1127                          * a one page request is never in violation.
1128                          */
1129                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1130                             mddev->queue->max_sectors > (PAGE_SIZE>>9))
1131                                 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
1132
1133                         p->head_position = 0;
1134                         rdev->raid_disk = mirror;
1135                         err = 0;
1136                         /* As all devices are equivalent, we don't need a full recovery
1137                          * if this was recently any drive of the array
1138                          */
1139                         if (rdev->saved_raid_disk < 0)
1140                                 conf->fullsync = 1;
1141                         rcu_assign_pointer(p->rdev, rdev);
1142                         break;
1143                 }
1144
1145         print_conf(conf);
1146         return err;
1147 }
1148
1149 static int raid1_remove_disk(mddev_t *mddev, int number)
1150 {
1151         conf_t *conf = mddev->private;
1152         int err = 0;
1153         mdk_rdev_t *rdev;
1154         mirror_info_t *p = conf->mirrors+ number;
1155
1156         print_conf(conf);
1157         rdev = p->rdev;
1158         if (rdev) {
1159                 if (test_bit(In_sync, &rdev->flags) ||
1160                     atomic_read(&rdev->nr_pending)) {
1161                         err = -EBUSY;
1162                         goto abort;
1163                 }
1164                 /* Only remove non-faulty devices is recovery
1165                  * is not possible.
1166                  */
1167                 if (!test_bit(Faulty, &rdev->flags) &&
1168                     mddev->degraded < conf->raid_disks) {
1169                         err = -EBUSY;
1170                         goto abort;
1171                 }
1172                 p->rdev = NULL;
1173                 synchronize_rcu();
1174                 if (atomic_read(&rdev->nr_pending)) {
1175                         /* lost the race, try later */
1176                         err = -EBUSY;
1177                         p->rdev = rdev;
1178                 }
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 = (r1bio_t *)(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 = (r1bio_t *)(bio->bi_private);
1213         mddev_t *mddev = r1_bio->mddev;
1214         conf_t *conf = mddev_to_conf(mddev);
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                 int 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_to_conf(mddev);
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->bdev,
1368                                                          sect + rdev->data_offset,
1369                                                          s<<9,
1370                                                          bio->bi_io_vec[idx].bv_page,
1371                                                          READ)) {
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->bdev,
1394                                                          sect + rdev->data_offset,
1395                                                          s<<9,
1396                                                          bio->bi_io_vec[idx].bv_page,
1397                                                          WRITE) == 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->bdev,
1409                                                          sect + rdev->data_offset,
1410                                                          s<<9,
1411                                                          bio->bi_io_vec[idx].bv_page,
1412                                                          READ) == 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 "raid1: %s: unrecoverable I/O read error"
1420                                        " for block %llu\n",
1421                                        bdevname(bio->bi_bdev,b),
1422                                        (unsigned long long)r1_bio->sector);
1423                                 md_done_sync(mddev, r1_bio->sectors, 0);
1424                                 put_buf(r1_bio);
1425                                 return;
1426                         }
1427                         sectors -= s;
1428                         sect += s;
1429                         idx ++;
1430                 }
1431         }
1432
1433         /*
1434          * schedule writes
1435          */
1436         atomic_set(&r1_bio->remaining, 1);
1437         for (i = 0; i < disks ; i++) {
1438                 wbio = r1_bio->bios[i];
1439                 if (wbio->bi_end_io == NULL ||
1440                     (wbio->bi_end_io == end_sync_read &&
1441                      (i == r1_bio->read_disk ||
1442                       !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
1443                         continue;
1444
1445                 wbio->bi_rw = WRITE;
1446                 wbio->bi_end_io = end_sync_write;
1447                 atomic_inc(&r1_bio->remaining);
1448                 md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
1449
1450                 generic_make_request(wbio);
1451         }
1452
1453         if (atomic_dec_and_test(&r1_bio->remaining)) {
1454                 /* if we're here, all write(s) have completed, so clean up */
1455                 md_done_sync(mddev, r1_bio->sectors, 1);
1456                 put_buf(r1_bio);
1457         }
1458 }
1459
1460 /*
1461  * This is a kernel thread which:
1462  *
1463  *      1.      Retries failed read operations on working mirrors.
1464  *      2.      Updates the raid superblock when problems encounter.
1465  *      3.      Performs writes following reads for array syncronising.
1466  */
1467
1468 static void fix_read_error(conf_t *conf, int read_disk,
1469                            sector_t sect, int sectors)
1470 {
1471         mddev_t *mddev = conf->mddev;
1472         while(sectors) {
1473                 int s = sectors;
1474                 int d = read_disk;
1475                 int success = 0;
1476                 int start;
1477                 mdk_rdev_t *rdev;
1478
1479                 if (s > (PAGE_SIZE>>9))
1480                         s = PAGE_SIZE >> 9;
1481
1482                 do {
1483                         /* Note: no rcu protection needed here
1484                          * as this is synchronous in the raid1d thread
1485                          * which is the thread that might remove
1486                          * a device.  If raid1d ever becomes multi-threaded....
1487                          */
1488                         rdev = conf->mirrors[d].rdev;
1489                         if (rdev &&
1490                             test_bit(In_sync, &rdev->flags) &&
1491                             sync_page_io(rdev->bdev,
1492                                          sect + rdev->data_offset,
1493                                          s<<9,
1494                                          conf->tmppage, READ))
1495                                 success = 1;
1496                         else {
1497                                 d++;
1498                                 if (d == conf->raid_disks)
1499                                         d = 0;
1500                         }
1501                 } while (!success && d != read_disk);
1502
1503                 if (!success) {
1504                         /* Cannot read from anywhere -- bye bye array */
1505                         md_error(mddev, conf->mirrors[read_disk].rdev);
1506                         break;
1507                 }
1508                 /* write it back and re-read */
1509                 start = d;
1510                 while (d != read_disk) {
1511                         if (d==0)
1512                                 d = conf->raid_disks;
1513                         d--;
1514                         rdev = conf->mirrors[d].rdev;
1515                         if (rdev &&
1516                             test_bit(In_sync, &rdev->flags)) {
1517                                 if (sync_page_io(rdev->bdev,
1518                                                  sect + rdev->data_offset,
1519                                                  s<<9, conf->tmppage, WRITE)
1520                                     == 0)
1521                                         /* Well, this device is dead */
1522                                         md_error(mddev, rdev);
1523                         }
1524                 }
1525                 d = start;
1526                 while (d != read_disk) {
1527                         char b[BDEVNAME_SIZE];
1528                         if (d==0)
1529                                 d = conf->raid_disks;
1530                         d--;
1531                         rdev = conf->mirrors[d].rdev;
1532                         if (rdev &&
1533                             test_bit(In_sync, &rdev->flags)) {
1534                                 if (sync_page_io(rdev->bdev,
1535                                                  sect + rdev->data_offset,
1536                                                  s<<9, conf->tmppage, READ)
1537                                     == 0)
1538                                         /* Well, this device is dead */
1539                                         md_error(mddev, rdev);
1540                                 else {
1541                                         atomic_add(s, &rdev->corrected_errors);
1542                                         printk(KERN_INFO
1543                                                "raid1:%s: read error corrected "
1544                                                "(%d sectors at %llu on %s)\n",
1545                                                mdname(mddev), s,
1546                                                (unsigned long long)(sect +
1547                                                    rdev->data_offset),
1548                                                bdevname(rdev->bdev, b));
1549                                 }
1550                         }
1551                 }
1552                 sectors -= s;
1553                 sect += s;
1554         }
1555 }
1556
1557 static void raid1d(mddev_t *mddev)
1558 {
1559         r1bio_t *r1_bio;
1560         struct bio *bio;
1561         unsigned long flags;
1562         conf_t *conf = mddev_to_conf(mddev);
1563         struct list_head *head = &conf->retry_list;
1564         int unplug=0;
1565         mdk_rdev_t *rdev;
1566
1567         md_check_recovery(mddev);
1568
1569         for (;;) {
1570                 char b[BDEVNAME_SIZE];
1571
1572                 unplug += flush_pending_writes(conf);
1573
1574                 spin_lock_irqsave(&conf->device_lock, flags);
1575                 if (list_empty(head)) {
1576                         spin_unlock_irqrestore(&conf->device_lock, flags);
1577                         break;
1578                 }
1579                 r1_bio = list_entry(head->prev, r1bio_t, retry_list);
1580                 list_del(head->prev);
1581                 conf->nr_queued--;
1582                 spin_unlock_irqrestore(&conf->device_lock, flags);
1583
1584                 mddev = r1_bio->mddev;
1585                 conf = mddev_to_conf(mddev);
1586                 if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
1587                         sync_request_write(mddev, r1_bio);
1588                         unplug = 1;
1589                 } else if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
1590                         /* some requests in the r1bio were BIO_RW_BARRIER
1591                          * requests which failed with -EOPNOTSUPP.  Hohumm..
1592                          * Better resubmit without the barrier.
1593                          * We know which devices to resubmit for, because
1594                          * all others have had their bios[] entry cleared.
1595                          * We already have a nr_pending reference on these rdevs.
1596                          */
1597                         int i;
1598                         const int do_sync = bio_sync(r1_bio->master_bio);
1599                         clear_bit(R1BIO_BarrierRetry, &r1_bio->state);
1600                         clear_bit(R1BIO_Barrier, &r1_bio->state);
1601                         for (i=0; i < conf->raid_disks; i++)
1602                                 if (r1_bio->bios[i])
1603                                         atomic_inc(&r1_bio->remaining);
1604                         for (i=0; i < conf->raid_disks; i++)
1605                                 if (r1_bio->bios[i]) {
1606                                         struct bio_vec *bvec;
1607                                         int j;
1608
1609                                         bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
1610                                         /* copy pages from the failed bio, as
1611                                          * this might be a write-behind device */
1612                                         __bio_for_each_segment(bvec, bio, j, 0)
1613                                                 bvec->bv_page = bio_iovec_idx(r1_bio->bios[i], j)->bv_page;
1614                                         bio_put(r1_bio->bios[i]);
1615                                         bio->bi_sector = r1_bio->sector +
1616                                                 conf->mirrors[i].rdev->data_offset;
1617                                         bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1618                                         bio->bi_end_io = raid1_end_write_request;
1619                                         bio->bi_rw = WRITE | do_sync;
1620                                         bio->bi_private = r1_bio;
1621                                         r1_bio->bios[i] = bio;
1622                                         generic_make_request(bio);
1623                                 }
1624                 } else {
1625                         int disk;
1626
1627                         /* we got a read error. Maybe the drive is bad.  Maybe just
1628                          * the block and we can fix it.
1629                          * We freeze all other IO, and try reading the block from
1630                          * other devices.  When we find one, we re-write
1631                          * and check it that fixes the read error.
1632                          * This is all done synchronously while the array is
1633                          * frozen
1634                          */
1635                         if (mddev->ro == 0) {
1636                                 freeze_array(conf);
1637                                 fix_read_error(conf, r1_bio->read_disk,
1638                                                r1_bio->sector,
1639                                                r1_bio->sectors);
1640                                 unfreeze_array(conf);
1641                         }
1642
1643                         bio = r1_bio->bios[r1_bio->read_disk];
1644                         if ((disk=read_balance(conf, r1_bio)) == -1 ||
1645                             disk == r1_bio->read_disk) {
1646                                 printk(KERN_ALERT "raid1: %s: unrecoverable I/O"
1647                                        " read error for block %llu\n",
1648                                        bdevname(bio->bi_bdev,b),
1649                                        (unsigned long long)r1_bio->sector);
1650                                 raid_end_bio_io(r1_bio);
1651                         } else {
1652                                 const int do_sync = bio_sync(r1_bio->master_bio);
1653                                 r1_bio->bios[r1_bio->read_disk] =
1654                                         mddev->ro ? IO_BLOCKED : NULL;
1655                                 r1_bio->read_disk = disk;
1656                                 bio_put(bio);
1657                                 bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
1658                                 r1_bio->bios[r1_bio->read_disk] = bio;
1659                                 rdev = conf->mirrors[disk].rdev;
1660                                 if (printk_ratelimit())
1661                                         printk(KERN_ERR "raid1: %s: redirecting sector %llu to"
1662                                                " another mirror\n",
1663                                                bdevname(rdev->bdev,b),
1664                                                (unsigned long long)r1_bio->sector);
1665                                 bio->bi_sector = r1_bio->sector + rdev->data_offset;
1666                                 bio->bi_bdev = rdev->bdev;
1667                                 bio->bi_end_io = raid1_end_read_request;
1668                                 bio->bi_rw = READ | do_sync;
1669                                 bio->bi_private = r1_bio;
1670                                 unplug = 1;
1671                                 generic_make_request(bio);
1672                         }
1673                 }
1674         }
1675         if (unplug)
1676                 unplug_slaves(mddev);
1677 }
1678
1679
1680 static int init_resync(conf_t *conf)
1681 {
1682         int buffs;
1683
1684         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1685         BUG_ON(conf->r1buf_pool);
1686         conf->r1buf_pool = mempool_create(buffs, r1buf_pool_alloc, r1buf_pool_free,
1687                                           conf->poolinfo);
1688         if (!conf->r1buf_pool)
1689                 return -ENOMEM;
1690         conf->next_resync = 0;
1691         return 0;
1692 }
1693
1694 /*
1695  * perform a "sync" on one "block"
1696  *
1697  * We need to make sure that no normal I/O request - particularly write
1698  * requests - conflict with active sync requests.
1699  *
1700  * This is achieved by tracking pending requests and a 'barrier' concept
1701  * that can be installed to exclude normal IO requests.
1702  */
1703
1704 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1705 {
1706         conf_t *conf = mddev_to_conf(mddev);
1707         r1bio_t *r1_bio;
1708         struct bio *bio;
1709         sector_t max_sector, nr_sectors;
1710         int disk = -1;
1711         int i;
1712         int wonly = -1;
1713         int write_targets = 0, read_targets = 0;
1714         int sync_blocks;
1715         int still_degraded = 0;
1716
1717         if (!conf->r1buf_pool)
1718         {
1719 /*
1720                 printk("sync start - bitmap %p\n", mddev->bitmap);
1721 */
1722                 if (init_resync(conf))
1723                         return 0;
1724         }
1725
1726         max_sector = mddev->size << 1;
1727         if (sector_nr >= max_sector) {
1728                 /* If we aborted, we need to abort the
1729                  * sync on the 'current' bitmap chunk (there will
1730                  * only be one in raid1 resync.
1731                  * We can find the current addess in mddev->curr_resync
1732                  */
1733                 if (mddev->curr_resync < max_sector) /* aborted */
1734                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1735                                                 &sync_blocks, 1);
1736                 else /* completed sync */
1737                         conf->fullsync = 0;
1738
1739                 bitmap_close_sync(mddev->bitmap);
1740                 close_sync(conf);
1741                 return 0;
1742         }
1743
1744         if (mddev->bitmap == NULL &&
1745             mddev->recovery_cp == MaxSector &&
1746             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
1747             conf->fullsync == 0) {
1748                 *skipped = 1;
1749                 return max_sector - sector_nr;
1750         }
1751         /* before building a request, check if we can skip these blocks..
1752          * This call the bitmap_start_sync doesn't actually record anything
1753          */
1754         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1755             !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1756                 /* We can skip this block, and probably several more */
1757                 *skipped = 1;
1758                 return sync_blocks;
1759         }
1760         /*
1761          * If there is non-resync activity waiting for a turn,
1762          * and resync is going fast enough,
1763          * then let it though before starting on this new sync request.
1764          */
1765         if (!go_faster && conf->nr_waiting)
1766                 msleep_interruptible(1000);
1767
1768         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
1769         raise_barrier(conf);
1770
1771         conf->next_resync = sector_nr;
1772
1773         r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
1774         rcu_read_lock();
1775         /*
1776          * If we get a correctably read error during resync or recovery,
1777          * we might want to read from a different device.  So we
1778          * flag all drives that could conceivably be read from for READ,
1779          * and any others (which will be non-In_sync devices) for WRITE.
1780          * If a read fails, we try reading from something else for which READ
1781          * is OK.
1782          */
1783
1784         r1_bio->mddev = mddev;
1785         r1_bio->sector = sector_nr;
1786         r1_bio->state = 0;
1787         set_bit(R1BIO_IsSync, &r1_bio->state);
1788
1789         for (i=0; i < conf->raid_disks; i++) {
1790                 mdk_rdev_t *rdev;
1791                 bio = r1_bio->bios[i];
1792
1793                 /* take from bio_init */
1794                 bio->bi_next = NULL;
1795                 bio->bi_flags |= 1 << BIO_UPTODATE;
1796                 bio->bi_rw = READ;
1797                 bio->bi_vcnt = 0;
1798                 bio->bi_idx = 0;
1799                 bio->bi_phys_segments = 0;
1800                 bio->bi_size = 0;
1801                 bio->bi_end_io = NULL;
1802                 bio->bi_private = NULL;
1803
1804                 rdev = rcu_dereference(conf->mirrors[i].rdev);
1805                 if (rdev == NULL ||
1806                            test_bit(Faulty, &rdev->flags)) {
1807                         still_degraded = 1;
1808                         continue;
1809                 } else if (!test_bit(In_sync, &rdev->flags)) {
1810                         bio->bi_rw = WRITE;
1811                         bio->bi_end_io = end_sync_write;
1812                         write_targets ++;
1813                 } else {
1814                         /* may need to read from here */
1815                         bio->bi_rw = READ;
1816                         bio->bi_end_io = end_sync_read;
1817                         if (test_bit(WriteMostly, &rdev->flags)) {
1818                                 if (wonly < 0)
1819                                         wonly = i;
1820                         } else {
1821                                 if (disk < 0)
1822                                         disk = i;
1823                         }
1824                         read_targets++;
1825                 }
1826                 atomic_inc(&rdev->nr_pending);
1827                 bio->bi_sector = sector_nr + rdev->data_offset;
1828                 bio->bi_bdev = rdev->bdev;
1829                 bio->bi_private = r1_bio;
1830         }
1831         rcu_read_unlock();
1832         if (disk < 0)
1833                 disk = wonly;
1834         r1_bio->read_disk = disk;
1835
1836         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
1837                 /* extra read targets are also write targets */
1838                 write_targets += read_targets-1;
1839
1840         if (write_targets == 0 || read_targets == 0) {
1841                 /* There is nowhere to write, so all non-sync
1842                  * drives must be failed - so we are finished
1843                  */
1844                 sector_t rv = max_sector - sector_nr;
1845                 *skipped = 1;
1846                 put_buf(r1_bio);
1847                 return rv;
1848         }
1849
1850         if (max_sector > mddev->resync_max)
1851                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
1852         nr_sectors = 0;
1853         sync_blocks = 0;
1854         do {
1855                 struct page *page;
1856                 int len = PAGE_SIZE;
1857                 if (sector_nr + (len>>9) > max_sector)
1858                         len = (max_sector - sector_nr) << 9;
1859                 if (len == 0)
1860                         break;
1861                 if (sync_blocks == 0) {
1862                         if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1863                                                &sync_blocks, still_degraded) &&
1864                             !conf->fullsync &&
1865                             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
1866                                 break;
1867                         BUG_ON(sync_blocks < (PAGE_SIZE>>9));
1868                         if (len > (sync_blocks<<9))
1869                                 len = sync_blocks<<9;
1870                 }
1871
1872                 for (i=0 ; i < conf->raid_disks; i++) {
1873                         bio = r1_bio->bios[i];
1874                         if (bio->bi_end_io) {
1875                                 page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
1876                                 if (bio_add_page(bio, page, len, 0) == 0) {
1877                                         /* stop here */
1878                                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
1879                                         while (i > 0) {
1880                                                 i--;
1881                                                 bio = r1_bio->bios[i];
1882                                                 if (bio->bi_end_io==NULL)
1883                                                         continue;
1884                                                 /* remove last page from this bio */
1885                                                 bio->bi_vcnt--;
1886                                                 bio->bi_size -= len;
1887                                                 bio->bi_flags &= ~(1<< BIO_SEG_VALID);
1888                                         }
1889                                         goto bio_full;
1890                                 }
1891                         }
1892                 }
1893                 nr_sectors += len>>9;
1894                 sector_nr += len>>9;
1895                 sync_blocks -= (len>>9);
1896         } while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
1897  bio_full:
1898         r1_bio->sectors = nr_sectors;
1899
1900         /* For a user-requested sync, we read all readable devices and do a
1901          * compare
1902          */
1903         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1904                 atomic_set(&r1_bio->remaining, read_targets);
1905                 for (i=0; i<conf->raid_disks; i++) {
1906                         bio = r1_bio->bios[i];
1907                         if (bio->bi_end_io == end_sync_read) {
1908                                 md_sync_acct(bio->bi_bdev, nr_sectors);
1909                                 generic_make_request(bio);
1910                         }
1911                 }
1912         } else {
1913                 atomic_set(&r1_bio->remaining, 1);
1914                 bio = r1_bio->bios[r1_bio->read_disk];
1915                 md_sync_acct(bio->bi_bdev, nr_sectors);
1916                 generic_make_request(bio);
1917
1918         }
1919         return nr_sectors;
1920 }
1921
1922 static int run(mddev_t *mddev)
1923 {
1924         conf_t *conf;
1925         int i, j, disk_idx;
1926         mirror_info_t *disk;
1927         mdk_rdev_t *rdev;
1928
1929         if (mddev->level != 1) {
1930                 printk("raid1: %s: raid level not set to mirroring (%d)\n",
1931                        mdname(mddev), mddev->level);
1932                 goto out;
1933         }
1934         if (mddev->reshape_position != MaxSector) {
1935                 printk("raid1: %s: reshape_position set but not supported\n",
1936                        mdname(mddev));
1937                 goto out;
1938         }
1939         /*
1940          * copy the already verified devices into our private RAID1
1941          * bookkeeping area. [whatever we allocate in run(),
1942          * should be freed in stop()]
1943          */
1944         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
1945         mddev->private = conf;
1946         if (!conf)
1947                 goto out_no_mem;
1948
1949         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
1950                                  GFP_KERNEL);
1951         if (!conf->mirrors)
1952                 goto out_no_mem;
1953
1954         conf->tmppage = alloc_page(GFP_KERNEL);
1955         if (!conf->tmppage)
1956                 goto out_no_mem;
1957
1958         conf->poolinfo = kmalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
1959         if (!conf->poolinfo)
1960                 goto out_no_mem;
1961         conf->poolinfo->mddev = mddev;
1962         conf->poolinfo->raid_disks = mddev->raid_disks;
1963         conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
1964                                           r1bio_pool_free,
1965                                           conf->poolinfo);
1966         if (!conf->r1bio_pool)
1967                 goto out_no_mem;
1968
1969         spin_lock_init(&conf->device_lock);
1970         mddev->queue->queue_lock = &conf->device_lock;
1971
1972         list_for_each_entry(rdev, &mddev->disks, same_set) {
1973                 disk_idx = rdev->raid_disk;
1974                 if (disk_idx >= mddev->raid_disks
1975                     || disk_idx < 0)
1976                         continue;
1977                 disk = conf->mirrors + disk_idx;
1978
1979                 disk->rdev = rdev;
1980
1981                 blk_queue_stack_limits(mddev->queue,
1982                                        rdev->bdev->bd_disk->queue);
1983                 /* as we don't honour merge_bvec_fn, we must never risk
1984                  * violating it, so limit ->max_sector to one PAGE, as
1985                  * a one page request is never in violation.
1986                  */
1987                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1988                     mddev->queue->max_sectors > (PAGE_SIZE>>9))
1989                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
1990
1991                 disk->head_position = 0;
1992         }
1993         conf->raid_disks = mddev->raid_disks;
1994         conf->mddev = mddev;
1995         INIT_LIST_HEAD(&conf->retry_list);
1996
1997         spin_lock_init(&conf->resync_lock);
1998         init_waitqueue_head(&conf->wait_barrier);
1999
2000         bio_list_init(&conf->pending_bio_list);
2001         bio_list_init(&conf->flushing_bio_list);
2002
2003
2004         mddev->degraded = 0;
2005         for (i = 0; i < conf->raid_disks; i++) {
2006
2007                 disk = conf->mirrors + i;
2008
2009                 if (!disk->rdev ||
2010                     !test_bit(In_sync, &disk->rdev->flags)) {
2011                         disk->head_position = 0;
2012                         mddev->degraded++;
2013                         if (disk->rdev)
2014                                 conf->fullsync = 1;
2015                 }
2016         }
2017         if (mddev->degraded == conf->raid_disks) {
2018                 printk(KERN_ERR "raid1: no operational mirrors for %s\n",
2019                         mdname(mddev));
2020                 goto out_free_conf;
2021         }
2022         if (conf->raid_disks - mddev->degraded == 1)
2023                 mddev->recovery_cp = MaxSector;
2024
2025         /*
2026          * find the first working one and use it as a starting point
2027          * to read balancing.
2028          */
2029         for (j = 0; j < conf->raid_disks &&
2030                      (!conf->mirrors[j].rdev ||
2031                       !test_bit(In_sync, &conf->mirrors[j].rdev->flags)) ; j++)
2032                 /* nothing */;
2033         conf->last_used = j;
2034
2035
2036         mddev->thread = md_register_thread(raid1d, mddev, "%s_raid1");
2037         if (!mddev->thread) {
2038                 printk(KERN_ERR
2039                        "raid1: couldn't allocate thread for %s\n",
2040                        mdname(mddev));
2041                 goto out_free_conf;
2042         }
2043
2044         printk(KERN_INFO
2045                 "raid1: raid set %s active with %d out of %d mirrors\n",
2046                 mdname(mddev), mddev->raid_disks - mddev->degraded,
2047                 mddev->raid_disks);
2048         /*
2049          * Ok, everything is just fine now
2050          */
2051         mddev->array_sectors = mddev->size * 2;
2052
2053         mddev->queue->unplug_fn = raid1_unplug;
2054         mddev->queue->backing_dev_info.congested_fn = raid1_congested;
2055         mddev->queue->backing_dev_info.congested_data = mddev;
2056
2057         return 0;
2058
2059 out_no_mem:
2060         printk(KERN_ERR "raid1: couldn't allocate memory for %s\n",
2061                mdname(mddev));
2062
2063 out_free_conf:
2064         if (conf) {
2065                 if (conf->r1bio_pool)
2066                         mempool_destroy(conf->r1bio_pool);
2067                 kfree(conf->mirrors);
2068                 safe_put_page(conf->tmppage);
2069                 kfree(conf->poolinfo);
2070                 kfree(conf);
2071                 mddev->private = NULL;
2072         }
2073 out:
2074         return -EIO;
2075 }
2076
2077 static int stop(mddev_t *mddev)
2078 {
2079         conf_t *conf = mddev_to_conf(mddev);
2080         struct bitmap *bitmap = mddev->bitmap;
2081         int behind_wait = 0;
2082
2083         /* wait for behind writes to complete */
2084         while (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
2085                 behind_wait++;
2086                 printk(KERN_INFO "raid1: behind writes in progress on device %s, waiting to stop (%d)\n", mdname(mddev), behind_wait);
2087                 set_current_state(TASK_UNINTERRUPTIBLE);
2088                 schedule_timeout(HZ); /* wait a second */
2089                 /* need to kick something here to make sure I/O goes? */
2090         }
2091
2092         md_unregister_thread(mddev->thread);
2093         mddev->thread = NULL;
2094         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2095         if (conf->r1bio_pool)
2096                 mempool_destroy(conf->r1bio_pool);
2097         kfree(conf->mirrors);
2098         kfree(conf->poolinfo);
2099         kfree(conf);
2100         mddev->private = NULL;
2101         return 0;
2102 }
2103
2104 static int raid1_resize(mddev_t *mddev, sector_t sectors)
2105 {
2106         /* no resync is happening, and there is enough space
2107          * on all devices, so we can resize.
2108          * We need to make sure resync covers any new space.
2109          * If the array is shrinking we should possibly wait until
2110          * any io in the removed space completes, but it hardly seems
2111          * worth it.
2112          */
2113         mddev->array_sectors = sectors;
2114         set_capacity(mddev->gendisk, mddev->array_sectors);
2115         mddev->changed = 1;
2116         if (mddev->array_sectors / 2 > mddev->size &&
2117             mddev->recovery_cp == MaxSector) {
2118                 mddev->recovery_cp = mddev->size << 1;
2119                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2120         }
2121         mddev->size = mddev->array_sectors / 2;
2122         mddev->resync_max_sectors = sectors;
2123         return 0;
2124 }
2125
2126 static int raid1_reshape(mddev_t *mddev)
2127 {
2128         /* We need to:
2129          * 1/ resize the r1bio_pool
2130          * 2/ resize conf->mirrors
2131          *
2132          * We allocate a new r1bio_pool if we can.
2133          * Then raise a device barrier and wait until all IO stops.
2134          * Then resize conf->mirrors and swap in the new r1bio pool.
2135          *
2136          * At the same time, we "pack" the devices so that all the missing
2137          * devices have the higher raid_disk numbers.
2138          */
2139         mempool_t *newpool, *oldpool;
2140         struct pool_info *newpoolinfo;
2141         mirror_info_t *newmirrors;
2142         conf_t *conf = mddev_to_conf(mddev);
2143         int cnt, raid_disks;
2144         unsigned long flags;
2145         int d, d2, err;
2146
2147         /* Cannot change chunk_size, layout, or level */
2148         if (mddev->chunk_size != mddev->new_chunk ||
2149             mddev->layout != mddev->new_layout ||
2150             mddev->level != mddev->new_level) {
2151                 mddev->new_chunk = mddev->chunk_size;
2152                 mddev->new_layout = mddev->layout;
2153                 mddev->new_level = mddev->level;
2154                 return -EINVAL;
2155         }
2156
2157         err = md_allow_write(mddev);
2158         if (err)
2159                 return err;
2160
2161         raid_disks = mddev->raid_disks + mddev->delta_disks;
2162
2163         if (raid_disks < conf->raid_disks) {
2164                 cnt=0;
2165                 for (d= 0; d < conf->raid_disks; d++)
2166                         if (conf->mirrors[d].rdev)
2167                                 cnt++;
2168                 if (cnt > raid_disks)
2169                         return -EBUSY;
2170         }
2171
2172         newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
2173         if (!newpoolinfo)
2174                 return -ENOMEM;
2175         newpoolinfo->mddev = mddev;
2176         newpoolinfo->raid_disks = raid_disks;
2177
2178         newpool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2179                                  r1bio_pool_free, newpoolinfo);
2180         if (!newpool) {
2181                 kfree(newpoolinfo);
2182                 return -ENOMEM;
2183         }
2184         newmirrors = kzalloc(sizeof(struct mirror_info) * raid_disks, GFP_KERNEL);
2185         if (!newmirrors) {
2186                 kfree(newpoolinfo);
2187                 mempool_destroy(newpool);
2188                 return -ENOMEM;
2189         }
2190
2191         raise_barrier(conf);
2192
2193         /* ok, everything is stopped */
2194         oldpool = conf->r1bio_pool;
2195         conf->r1bio_pool = newpool;
2196
2197         for (d = d2 = 0; d < conf->raid_disks; d++) {
2198                 mdk_rdev_t *rdev = conf->mirrors[d].rdev;
2199                 if (rdev && rdev->raid_disk != d2) {
2200                         char nm[20];
2201                         sprintf(nm, "rd%d", rdev->raid_disk);
2202                         sysfs_remove_link(&mddev->kobj, nm);
2203                         rdev->raid_disk = d2;
2204                         sprintf(nm, "rd%d", rdev->raid_disk);
2205                         sysfs_remove_link(&mddev->kobj, nm);
2206                         if (sysfs_create_link(&mddev->kobj,
2207                                               &rdev->kobj, nm))
2208                                 printk(KERN_WARNING
2209                                        "md/raid1: cannot register "
2210                                        "%s for %s\n",
2211                                        nm, mdname(mddev));
2212                 }
2213                 if (rdev)
2214                         newmirrors[d2++].rdev = rdev;
2215         }
2216         kfree(conf->mirrors);
2217         conf->mirrors = newmirrors;
2218         kfree(conf->poolinfo);
2219         conf->poolinfo = newpoolinfo;
2220
2221         spin_lock_irqsave(&conf->device_lock, flags);
2222         mddev->degraded += (raid_disks - conf->raid_disks);
2223         spin_unlock_irqrestore(&conf->device_lock, flags);
2224         conf->raid_disks = mddev->raid_disks = raid_disks;
2225         mddev->delta_disks = 0;
2226
2227         conf->last_used = 0; /* just make sure it is in-range */
2228         lower_barrier(conf);
2229
2230         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2231         md_wakeup_thread(mddev->thread);
2232
2233         mempool_destroy(oldpool);
2234         return 0;
2235 }
2236
2237 static void raid1_quiesce(mddev_t *mddev, int state)
2238 {
2239         conf_t *conf = mddev_to_conf(mddev);
2240
2241         switch(state) {
2242         case 1:
2243                 raise_barrier(conf);
2244                 break;
2245         case 0:
2246                 lower_barrier(conf);
2247                 break;
2248         }
2249 }
2250
2251
2252 static struct mdk_personality raid1_personality =
2253 {
2254         .name           = "raid1",
2255         .level          = 1,
2256         .owner          = THIS_MODULE,
2257         .make_request   = make_request,
2258         .run            = run,
2259         .stop           = stop,
2260         .status         = status,
2261         .error_handler  = error,
2262         .hot_add_disk   = raid1_add_disk,
2263         .hot_remove_disk= raid1_remove_disk,
2264         .spare_active   = raid1_spare_active,
2265         .sync_request   = sync_request,
2266         .resize         = raid1_resize,
2267         .check_reshape  = raid1_reshape,
2268         .quiesce        = raid1_quiesce,
2269 };
2270
2271 static int __init raid_init(void)
2272 {
2273         return register_md_personality(&raid1_personality);
2274 }
2275
2276 static void raid_exit(void)
2277 {
2278         unregister_md_personality(&raid1_personality);
2279 }
2280
2281 module_init(raid_init);
2282 module_exit(raid_exit);
2283 MODULE_LICENSE("GPL");
2284 MODULE_ALIAS("md-personality-3"); /* RAID1 */
2285 MODULE_ALIAS("md-raid1");
2286 MODULE_ALIAS("md-level-1");