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/raid/raid1.h>
  36 #include <linux/raid/bitmap.h>
  37
  38 #define DEBUG 0
  39 #if DEBUG
  40 #define PRINTK(x...) printk(x)
  41 #else
  42 #define PRINTK(x...)
  43 #endif
  44
  45 /*
  46  * Number of guaranteed r1bios in case of extreme VM load:
  47  */
  48 #define NR_RAID1_BIOS 256
  49
  50
  51 static void unplug_slaves(mddev_t *mddev);
  52
  53 static void allow_barrier(conf_t *conf);
  54 static void lower_barrier(conf_t *conf);
  55
  56 static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
  57 {
  58         struct pool_info *pi = data;
  59         r1bio_t *r1_bio;
  60         int size = offsetof(r1bio_t, bios[pi->raid_disks]);
  61
  62         /* allocate a r1bio with room for raid_disks entries in the bios array */
  63         r1_bio = kzalloc(size, gfp_flags);
  64         if (!r1_bio)
  65                 unplug_slaves(pi->mddev);
  66
  67         return r1_bio;
  68 }
  69
  70 static void r1bio_pool_free(void *r1_bio, void *data)
  71 {
  72         kfree(r1_bio);
  73 }
  74
  75 #define RESYNC_BLOCK_SIZE (64*1024)
  76 //#define RESYNC_BLOCK_SIZE PAGE_SIZE
  77 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
  78 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
  79 #define RESYNC_WINDOW (2048*1024)
  80
  81 static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
  82 {
  83         struct pool_info *pi = data;
  84         struct page *page;
  85         r1bio_t *r1_bio;
  86         struct bio *bio;
  87         int i, j;
  88
  89         r1_bio = r1bio_pool_alloc(gfp_flags, pi);
  90         if (!r1_bio) {
  91                 unplug_slaves(pi->mddev);
  92                 return NULL;
  93         }
  94
  95         /*
  96          * Allocate bios : 1 for reading, n-1 for writing
  97          */
  98         for (j = pi->raid_disks ; j-- ; ) {
  99                 bio = bio_alloc(gfp_flags, RESYNC_PAGES);
 100                 if (!bio)
 101                         goto out_free_bio;
 102                 r1_bio->bios[j] = bio;
 103         }
 104         /*
 105          * Allocate RESYNC_PAGES data pages and attach them to
 106          * the first bio.
 107          * If this is a user-requested check/repair, allocate
 108          * RESYNC_PAGES for each bio.
 109          */
 110         if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
 111                 j = pi->raid_disks;
 112         else
 113                 j = 1;
 114         while(j--) {
 115                 bio = r1_bio->bios[j];
 116                 for (i = 0; i < RESYNC_PAGES; i++) {
 117                         page = alloc_page(gfp_flags);
 118                         if (unlikely(!page))
 119                                 goto out_free_pages;
 120
 121                         bio->bi_io_vec[i].bv_page = page;
 122                 }
 123         }
 124         /* If not user-requests, copy the page pointers to all bios */
 125         if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
 126                 for (i=0; i<RESYNC_PAGES ; i++)
 127                         for (j=1; j<pi->raid_disks; j++)
 128                                 r1_bio->bios[j]->bi_io_vec[i].bv_page =
 129                                         r1_bio->bios[0]->bi_io_vec[i].bv_page;
 130         }
 131
 132         r1_bio->master_bio = NULL;
 133
 134         return r1_bio;
 135
 136 out_free_pages:
 137         for (i=0; i < RESYNC_PAGES ; i++)
 138                 for (j=0 ; j < pi->raid_disks; j++)
 139                         safe_put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
 140         j = -1;
 141 out_free_bio:
 142         while ( ++j < pi->raid_disks )
 143                 bio_put(r1_bio->bios[j]);
 144         r1bio_pool_free(r1_bio, data);
 145         return NULL;
 146 }
 147
 148 static void r1buf_pool_free(void *__r1_bio, void *data)
 149 {
 150         struct pool_info *pi = data;
 151         int i,j;
 152         r1bio_t *r1bio = __r1_bio;
 153
 154         for (i = 0; i < RESYNC_PAGES; i++)
 155                 for (j = pi->raid_disks; j-- ;) {
 156                         if (j == 0 ||
 157                             r1bio->bios[j]->bi_io_vec[i].bv_page !=
 158                             r1bio->bios[0]->bi_io_vec[i].bv_page)
 159                                 safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
 160                 }
 161         for (i=0 ; i < pi->raid_disks; i++)
 162                 bio_put(r1bio->bios[i]);
 163
 164         r1bio_pool_free(r1bio, data);
 165 }
 166
 167 static void put_all_bios(conf_t *conf, r1bio_t *r1_bio)
 168 {
 169         int i;
 170
 171         for (i = 0; i < conf->raid_disks; i++) {
 172                 struct bio **bio = r1_bio->bios + i;
 173                 if (*bio && *bio != IO_BLOCKED)
 174                         bio_put(*bio);
 175                 *bio = NULL;
 176         }
 177 }
 178
 179 static void free_r1bio(r1bio_t *r1_bio)
 180 {
 181         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 182
 183         /*
 184          * Wake up any possible resync thread that waits for the device
 185          * to go idle.
 186          */
 187         allow_barrier(conf);
 188
 189         put_all_bios(conf, r1_bio);
 190         mempool_free(r1_bio, conf->r1bio_pool);
 191 }
 192
 193 static void put_buf(r1bio_t *r1_bio)
 194 {
 195         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 196         int i;
 197
 198         for (i=0; i<conf->raid_disks; i++) {
 199                 struct bio *bio = r1_bio->bios[i];
 200                 if (bio->bi_end_io)
 201                         rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
 202         }
 203
 204         mempool_free(r1_bio, conf->r1buf_pool);
 205
 206         lower_barrier(conf);
 207 }
 208
 209 static void reschedule_retry(r1bio_t *r1_bio)
 210 {
 211         unsigned long flags;
 212         mddev_t *mddev = r1_bio->mddev;
 213         conf_t *conf = mddev_to_conf(mddev);
 214
 215         spin_lock_irqsave(&conf->device_lock, flags);
 216         list_add(&r1_bio->retry_list, &conf->retry_list);
 217         conf->nr_queued ++;
 218         spin_unlock_irqrestore(&conf->device_lock, flags);
 219
 220         wake_up(&conf->wait_barrier);
 221         md_wakeup_thread(mddev->thread);
 222 }
 223
 224 /*
 225  * raid_end_bio_io() is called when we have finished servicing a mirrored
 226  * operation and are ready to return a success/failure code to the buffer
 227  * cache layer.
 228  */
 229 static void raid_end_bio_io(r1bio_t *r1_bio)
 230 {
 231         struct bio *bio = r1_bio->master_bio;
 232
 233         /* if nobody has done the final endio yet, do it now */
 234         if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 235                 PRINTK(KERN_DEBUG "raid1: sync end %s on sectors %llu-%llu\n",
 236                         (bio_data_dir(bio) == WRITE) ? "write" : "read",
 237                         (unsigned long long) bio->bi_sector,
 238                         (unsigned long long) bio->bi_sector +
 239                                 (bio->bi_size >> 9) - 1);
 240
 241                 bio_endio(bio, bio->bi_size,
 242                         test_bit(R1BIO_Uptodate, &r1_bio->state) ? 0 : -EIO);
 243         }
 244         free_r1bio(r1_bio);
 245 }
 246
 247 /*
 248  * Update disk head position estimator based on IRQ completion info.
 249  */
 250 static inline void update_head_pos(int disk, r1bio_t *r1_bio)
 251 {
 252         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 253
 254         conf->mirrors[disk].head_position =
 255                 r1_bio->sector + (r1_bio->sectors);
 256 }
 257
 258 static int raid1_end_read_request(struct bio *bio, unsigned int bytes_done, int error)
 259 {
 260         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 261         r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
 262         int mirror;
 263         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 264
 265         if (bio->bi_size)
 266                 return 1;
 267
 268         mirror = r1_bio->read_disk;
 269         /*
 270          * this branch is our 'one mirror IO has finished' event handler:
 271          */
 272         update_head_pos(mirror, r1_bio);
 273
 274         if (uptodate || conf->working_disks <= 1) {
 275                 /*
 276                  * Set R1BIO_Uptodate in our master bio, so that
 277                  * we will return a good error code for to the higher
 278                  * levels even if IO on some other mirrored buffer fails.
 279                  *
 280                  * The 'master' represents the composite IO operation to
 281                  * user-side. So if something waits for IO, then it will
 282                  * wait for the 'master' bio.
 283                  */
 284                 if (uptodate)
 285                         set_bit(R1BIO_Uptodate, &r1_bio->state);
 286
 287                 raid_end_bio_io(r1_bio);
 288         } else {
 289                 /*
 290                  * oops, read error:
 291                  */
 292                 char b[BDEVNAME_SIZE];
 293                 if (printk_ratelimit())
 294                         printk(KERN_ERR "raid1: %s: rescheduling sector %llu\n",
 295                                bdevname(conf->mirrors[mirror].rdev->bdev,b), (unsigned long long)r1_bio->sector);
 296                 reschedule_retry(r1_bio);
 297         }
 298
 299         rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 300         return 0;
 301 }
 302
 303 static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int error)
 304 {
 305         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 306         r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
 307         int mirror, behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
 308         conf_t *conf = mddev_to_conf(r1_bio->mddev);
 309         struct bio *to_put = NULL;
 310
 311         if (bio->bi_size)
 312                 return 1;
 313
 314         for (mirror = 0; mirror < conf->raid_disks; mirror++)
 315                 if (r1_bio->bios[mirror] == bio)
 316                         break;
 317
 318         if (error == -ENOTSUPP && test_bit(R1BIO_Barrier, &r1_bio->state)) {
 319                 set_bit(BarriersNotsupp, &conf->mirrors[mirror].rdev->flags);
 320                 set_bit(R1BIO_BarrierRetry, &r1_bio->state);
 321                 r1_bio->mddev->barriers_work = 0;
 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, mbio->bi_size, 0);
 365                                 }
 366                         }
 367                 }
 368         }
 369         /*
 370          *
 371          * Let's see if all mirrored write operations have finished
 372          * already.
 373          */
 374         if (atomic_dec_and_test(&r1_bio->remaining)) {
 375                 if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
 376                         reschedule_retry(r1_bio);
 377                         /* Don't dec_pending yet, we want to hold
 378                          * the reference over the retry
 379                          */
 380                         goto out;
 381                 }
 382                 if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
 383                         /* free extra copy of the data pages */
 384                         int i = bio->bi_vcnt;
 385                         while (i--)
 386                                 safe_put_page(bio->bi_io_vec[i].bv_page);
 387                 }
 388                 /* clear the bitmap if all writes complete successfully */
 389                 bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
 390                                 r1_bio->sectors,
 391                                 !test_bit(R1BIO_Degraded, &r1_bio->state),
 392                                 behind);
 393                 md_write_end(r1_bio->mddev);
 394                 raid_end_bio_io(r1_bio);
 395         }
 396
 397         rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 398  out:
 399         if (to_put)
 400                 bio_put(to_put);
 401
 402         return 0;
 403 }
 404
 405
 406 /*
 407  * This routine returns the disk from which the requested read should
 408  * be done. There is a per-array 'next expected sequential IO' sector
 409  * number - if this matches on the next IO then we use the last disk.
 410  * There is also a per-disk 'last know head position' sector that is
 411  * maintained from IRQ contexts, both the normal and the resync IO
 412  * completion handlers update this position correctly. If there is no
 413  * perfect sequential match then we pick the disk whose head is closest.
 414  *
 415  * If there are 2 mirrors in the same 2 devices, performance degrades
 416  * because position is mirror, not device based.
 417  *
 418  * The rdev for the device selected will have nr_pending incremented.
 419  */
 420 static int read_balance(conf_t *conf, r1bio_t *r1_bio)
 421 {
 422         const unsigned long this_sector = r1_bio->sector;
 423         int new_disk = conf->last_used, disk = new_disk;
 424         int wonly_disk = -1;
 425         const int sectors = r1_bio->sectors;
 426         sector_t new_distance, current_distance;
 427         mdk_rdev_t *rdev;
 428
 429         rcu_read_lock();
 430         /*
 431          * Check if we can balance. We can balance on the whole
 432          * device if no resync is going on, or below the resync window.
 433          * We take the first readable disk when above the resync window.
 434          */
 435  retry:
 436         if (conf->mddev->recovery_cp < MaxSector &&
 437             (this_sector + sectors >= conf->next_resync)) {
 438                 /* Choose the first operation device, for consistancy */
 439                 new_disk = 0;
 440
 441                 for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 442                      r1_bio->bios[new_disk] == IO_BLOCKED ||
 443                      !rdev || !test_bit(In_sync, &rdev->flags)
 444                              || test_bit(WriteMostly, &rdev->flags);
 445                      rdev = rcu_dereference(conf->mirrors[++new_disk].rdev)) {
 446
 447                         if (rdev && test_bit(In_sync, &rdev->flags) &&
 448                                 r1_bio->bios[new_disk] != IO_BLOCKED)
 449                                 wonly_disk = new_disk;
 450
 451                         if (new_disk == conf->raid_disks - 1) {
 452                                 new_disk = wonly_disk;
 453                                 break;
 454                         }
 455                 }
 456                 goto rb_out;
 457         }
 458
 459
 460         /* make sure the disk is operational */
 461         for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 462              r1_bio->bios[new_disk] == IO_BLOCKED ||
 463              !rdev || !test_bit(In_sync, &rdev->flags) ||
 464                      test_bit(WriteMostly, &rdev->flags);
 465              rdev = rcu_dereference(conf->mirrors[new_disk].rdev)) {
 466
 467                 if (rdev && test_bit(In_sync, &rdev->flags) &&
 468                     r1_bio->bios[new_disk] != IO_BLOCKED)
 469                         wonly_disk = new_disk;
 470
 471                 if (new_disk <= 0)
 472                         new_disk = conf->raid_disks;
 473                 new_disk--;
 474                 if (new_disk == disk) {
 475                         new_disk = wonly_disk;
 476                         break;
 477                 }
 478         }
 479
 480         if (new_disk < 0)
 481                 goto rb_out;
 482
 483         disk = new_disk;
 484         /* now disk == new_disk == starting point for search */
 485
 486         /*
 487          * Don't change to another disk for sequential reads:
 488          */
 489         if (conf->next_seq_sect == this_sector)
 490                 goto rb_out;
 491         if (this_sector == conf->mirrors[new_disk].head_position)
 492                 goto rb_out;
 493
 494         current_distance = abs(this_sector - conf->mirrors[disk].head_position);
 495
 496         /* Find the disk whose head is closest */
 497
 498         do {
 499                 if (disk <= 0)
 500                         disk = conf->raid_disks;
 501                 disk--;
 502
 503                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 504
 505                 if (!rdev || r1_bio->bios[disk] == IO_BLOCKED ||
 506                     !test_bit(In_sync, &rdev->flags) ||
 507                     test_bit(WriteMostly, &rdev->flags))
 508                         continue;
 509
 510                 if (!atomic_read(&rdev->nr_pending)) {
 511                         new_disk = disk;
 512                         break;
 513                 }
 514                 new_distance = abs(this_sector - conf->mirrors[disk].head_position);
 515                 if (new_distance < current_distance) {
 516                         current_distance = new_distance;
 517                         new_disk = disk;
 518                 }
 519         } while (disk != conf->last_used);
 520
 521  rb_out:
 522
 523
 524         if (new_disk >= 0) {
 525                 rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 526                 if (!rdev)
 527                         goto retry;
 528                 atomic_inc(&rdev->nr_pending);
 529                 if (!test_bit(In_sync, &rdev->flags)) {
 530                         /* cannot risk returning a device that failed
 531                          * before we inc'ed nr_pending
 532                          */
 533                         rdev_dec_pending(rdev, conf->mddev);
 534                         goto retry;
 535                 }
 536                 conf->next_seq_sect = this_sector + sectors;
 537                 conf->last_used = new_disk;
 538         }
 539         rcu_read_unlock();
 540
 541         return new_disk;
 542 }
 543
 544 static void unplug_slaves(mddev_t *mddev)
 545 {
 546         conf_t *conf = mddev_to_conf(mddev);
 547         int i;
 548
 549         rcu_read_lock();
 550         for (i=0; i<mddev->raid_disks; i++) {
 551                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 552                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
 553                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
 554
 555                         atomic_inc(&rdev->nr_pending);
 556                         rcu_read_unlock();
 557
 558                         if (r_queue->unplug_fn)
 559                                 r_queue->unplug_fn(r_queue);
 560
 561                         rdev_dec_pending(rdev, mddev);
 562                         rcu_read_lock();
 563                 }
 564         }
 565         rcu_read_unlock();
 566 }
 567
 568 static void raid1_unplug(request_queue_t *q)
 569 {
 570         mddev_t *mddev = q->queuedata;
 571
 572         unplug_slaves(mddev);
 573         md_wakeup_thread(mddev->thread);
 574 }
 575
 576 static int raid1_issue_flush(request_queue_t *q, struct gendisk *disk,
 577                              sector_t *error_sector)
 578 {
 579         mddev_t *mddev = q->queuedata;
 580         conf_t *conf = mddev_to_conf(mddev);
 581         int i, ret = 0;
 582
 583         rcu_read_lock();
 584         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
 585                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 586                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 587                         struct block_device *bdev = rdev->bdev;
 588                         request_queue_t *r_queue = bdev_get_queue(bdev);
 589
 590                         if (!r_queue->issue_flush_fn)
 591                                 ret = -EOPNOTSUPP;
 592                         else {
 593                                 atomic_inc(&rdev->nr_pending);
 594                                 rcu_read_unlock();
 595                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
 596                                                               error_sector);
 597                                 rdev_dec_pending(rdev, mddev);
 598                                 rcu_read_lock();
 599                         }
 600                 }
 601         }
 602         rcu_read_unlock();
 603         return ret;
 604 }
 605
 606 /* Barriers....
 607  * Sometimes we need to suspend IO while we do something else,
 608  * either some resync/recovery, or reconfigure the array.
 609  * To do this we raise a 'barrier'.
 610  * The 'barrier' is a counter that can be raised multiple times
 611  * to count how many activities are happening which preclude
 612  * normal IO.
 613  * We can only raise the barrier if there is no pending IO.
 614  * i.e. if nr_pending == 0.
 615  * We choose only to raise the barrier if no-one is waiting for the
 616  * barrier to go down.  This means that as soon as an IO request
 617  * is ready, no other operations which require a barrier will start
 618  * until the IO request has had a chance.
 619  *
 620  * So: regular IO calls 'wait_barrier'.  When that returns there
 621  *    is no backgroup IO happening,  It must arrange to call
 622  *    allow_barrier when it has finished its IO.
 623  * backgroup IO calls must call raise_barrier.  Once that returns
 624  *    there is no normal IO happeing.  It must arrange to call
 625  *    lower_barrier when the particular background IO completes.
 626  */
 627 #define RESYNC_DEPTH 32
 628
 629 static void raise_barrier(conf_t *conf)
 630 {
 631         spin_lock_irq(&conf->resync_lock);
 632
 633         /* Wait until no block IO is waiting */
 634         wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
 635                             conf->resync_lock,
 636                             raid1_unplug(conf->mddev->queue));
 637
 638         /* block any new IO from starting */
 639         conf->barrier++;
 640
 641         /* No wait for all pending IO to complete */
 642         wait_event_lock_irq(conf->wait_barrier,
 643                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 644                             conf->resync_lock,
 645                             raid1_unplug(conf->mddev->queue));
 646
 647         spin_unlock_irq(&conf->resync_lock);
 648 }
 649
 650 static void lower_barrier(conf_t *conf)
 651 {
 652         unsigned long flags;
 653         spin_lock_irqsave(&conf->resync_lock, flags);
 654         conf->barrier--;
 655         spin_unlock_irqrestore(&conf->resync_lock, flags);
 656         wake_up(&conf->wait_barrier);
 657 }
 658
 659 static void wait_barrier(conf_t *conf)
 660 {
 661         spin_lock_irq(&conf->resync_lock);
 662         if (conf->barrier) {
 663                 conf->nr_waiting++;
 664                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
 665                                     conf->resync_lock,
 666                                     raid1_unplug(conf->mddev->queue));
 667                 conf->nr_waiting--;
 668         }
 669         conf->nr_pending++;
 670         spin_unlock_irq(&conf->resync_lock);
 671 }
 672
 673 static void allow_barrier(conf_t *conf)
 674 {
 675         unsigned long flags;
 676         spin_lock_irqsave(&conf->resync_lock, flags);
 677         conf->nr_pending--;
 678         spin_unlock_irqrestore(&conf->resync_lock, flags);
 679         wake_up(&conf->wait_barrier);
 680 }
 681
 682 static void freeze_array(conf_t *conf)
 683 {
 684         /* stop syncio and normal IO and wait for everything to
 685          * go quite.
 686          * We increment barrier and nr_waiting, and then
 687          * wait until barrier+nr_pending match nr_queued+2
 688          */
 689         spin_lock_irq(&conf->resync_lock);
 690         conf->barrier++;
 691         conf->nr_waiting++;
 692         wait_event_lock_irq(conf->wait_barrier,
 693                             conf->barrier+conf->nr_pending == conf->nr_queued+2,
 694                             conf->resync_lock,
 695                             raid1_unplug(conf->mddev->queue));
 696         spin_unlock_irq(&conf->resync_lock);
 697 }
 698 static void unfreeze_array(conf_t *conf)
 699 {
 700         /* reverse the effect of the freeze */
 701         spin_lock_irq(&conf->resync_lock);
 702         conf->barrier--;
 703         conf->nr_waiting--;
 704         wake_up(&conf->wait_barrier);
 705         spin_unlock_irq(&conf->resync_lock);
 706 }
 707
 708
 709 /* duplicate the data pages for behind I/O */
 710 static struct page **alloc_behind_pages(struct bio *bio)
 711 {
 712         int i;
 713         struct bio_vec *bvec;
 714         struct page **pages = kzalloc(bio->bi_vcnt * sizeof(struct page *),
 715                                         GFP_NOIO);
 716         if (unlikely(!pages))
 717                 goto do_sync_io;
 718
 719         bio_for_each_segment(bvec, bio, i) {
 720                 pages[i] = alloc_page(GFP_NOIO);
 721                 if (unlikely(!pages[i]))
 722                         goto do_sync_io;
 723                 memcpy(kmap(pages[i]) + bvec->bv_offset,
 724                         kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
 725                 kunmap(pages[i]);
 726                 kunmap(bvec->bv_page);
 727         }
 728
 729         return pages;
 730
 731 do_sync_io:
 732         if (pages)
 733                 for (i = 0; i < bio->bi_vcnt && pages[i]; i++)
 734                         put_page(pages[i]);
 735         kfree(pages);
 736         PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
 737         return NULL;
 738 }
 739
 740 static int make_request(request_queue_t *q, struct bio * bio)
 741 {
 742         mddev_t *mddev = q->queuedata;
 743         conf_t *conf = mddev_to_conf(mddev);
 744         mirror_info_t *mirror;
 745         r1bio_t *r1_bio;
 746         struct bio *read_bio;
 747         int i, targets = 0, disks;
 748         mdk_rdev_t *rdev;
 749         struct bitmap *bitmap = mddev->bitmap;
 750         unsigned long flags;
 751         struct bio_list bl;
 752         struct page **behind_pages = NULL;
 753         const int rw = bio_data_dir(bio);
 754         int do_barriers;
 755
 756         if (unlikely(!mddev->barriers_work && bio_barrier(bio))) {
 757                 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
 758                 return 0;
 759         }
 760
 761         /*
 762          * Register the new request and wait if the reconstruction
 763          * thread has put up a bar for new requests.
 764          * Continue immediately if no resync is active currently.
 765          */
 766         md_write_start(mddev, bio); /* wait on superblock update early */
 767
 768         wait_barrier(conf);
 769
 770         disk_stat_inc(mddev->gendisk, ios[rw]);
 771         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
 772
 773         /*
 774          * make_request() can abort the operation when READA is being
 775          * used and no empty request is available.
 776          *
 777          */
 778         r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
 779
 780         r1_bio->master_bio = bio;
 781         r1_bio->sectors = bio->bi_size >> 9;
 782         r1_bio->state = 0;
 783         r1_bio->mddev = mddev;
 784         r1_bio->sector = bio->bi_sector;
 785
 786         if (rw == READ) {
 787                 /*
 788                  * read balancing logic:
 789                  */
 790                 int rdisk = read_balance(conf, r1_bio);
 791
 792                 if (rdisk < 0) {
 793                         /* couldn't find anywhere to read from */
 794                         raid_end_bio_io(r1_bio);
 795                         return 0;
 796                 }
 797                 mirror = conf->mirrors + rdisk;
 798
 799                 r1_bio->read_disk = rdisk;
 800
 801                 read_bio = bio_clone(bio, GFP_NOIO);
 802
 803                 r1_bio->bios[rdisk] = read_bio;
 804
 805                 read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
 806                 read_bio->bi_bdev = mirror->rdev->bdev;
 807                 read_bio->bi_end_io = raid1_end_read_request;
 808                 read_bio->bi_rw = READ;
 809                 read_bio->bi_private = r1_bio;
 810
 811                 generic_make_request(read_bio);
 812                 return 0;
 813         }
 814
 815         /*
 816          * WRITE:
 817          */
 818         /* first select target devices under spinlock and
 819          * inc refcount on their rdev.  Record them by setting
 820          * bios[x] to bio
 821          */
 822         disks = conf->raid_disks;
 823 #if 0
 824         { static int first=1;
 825         if (first) printk("First Write sector %llu disks %d\n",
 826                           (unsigned long long)r1_bio->sector, disks);
 827         first = 0;
 828         }
 829 #endif
 830         rcu_read_lock();
 831         for (i = 0;  i < disks; i++) {
 832                 if ((rdev=rcu_dereference(conf->mirrors[i].rdev)) != NULL &&
 833                     !test_bit(Faulty, &rdev->flags)) {
 834                         atomic_inc(&rdev->nr_pending);
 835                         if (test_bit(Faulty, &rdev->flags)) {
 836                                 rdev_dec_pending(rdev, mddev);
 837                                 r1_bio->bios[i] = NULL;
 838                         } else
 839                                 r1_bio->bios[i] = bio;
 840                         targets++;
 841                 } else
 842                         r1_bio->bios[i] = NULL;
 843         }
 844         rcu_read_unlock();
 845
 846         BUG_ON(targets == 0); /* we never fail the last device */
 847
 848         if (targets < conf->raid_disks) {
 849                 /* array is degraded, we will not clear the bitmap
 850                  * on I/O completion (see raid1_end_write_request) */
 851                 set_bit(R1BIO_Degraded, &r1_bio->state);
 852         }
 853
 854         /* do behind I/O ? */
 855         if (bitmap &&
 856             atomic_read(&bitmap->behind_writes) < bitmap->max_write_behind &&
 857             (behind_pages = alloc_behind_pages(bio)) != NULL)
 858                 set_bit(R1BIO_BehindIO, &r1_bio->state);
 859
 860         atomic_set(&r1_bio->remaining, 0);
 861         atomic_set(&r1_bio->behind_remaining, 0);
 862
 863         do_barriers = bio_barrier(bio);
 864         if (do_barriers)
 865                 set_bit(R1BIO_Barrier, &r1_bio->state);
 866
 867         bio_list_init(&bl);
 868         for (i = 0; i < disks; i++) {
 869                 struct bio *mbio;
 870                 if (!r1_bio->bios[i])
 871                         continue;
 872
 873                 mbio = bio_clone(bio, GFP_NOIO);
 874                 r1_bio->bios[i] = mbio;
 875
 876                 mbio->bi_sector = r1_bio->sector + conf->mirrors[i].rdev->data_offset;
 877                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
 878                 mbio->bi_end_io = raid1_end_write_request;
 879                 mbio->bi_rw = WRITE | do_barriers;
 880                 mbio->bi_private = r1_bio;
 881
 882                 if (behind_pages) {
 883                         struct bio_vec *bvec;
 884                         int j;
 885
 886                         /* Yes, I really want the '__' version so that
 887                          * we clear any unused pointer in the io_vec, rather
 888                          * than leave them unchanged.  This is important
 889                          * because when we come to free the pages, we won't
 890                          * know the originial bi_idx, so we just free
 891                          * them all
 892                          */
 893                         __bio_for_each_segment(bvec, mbio, j, 0)
 894                                 bvec->bv_page = behind_pages[j];
 895                         if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
 896                                 atomic_inc(&r1_bio->behind_remaining);
 897                 }
 898
 899                 atomic_inc(&r1_bio->remaining);
 900
 901                 bio_list_add(&bl, mbio);
 902         }
 903         kfree(behind_pages); /* the behind pages are attached to the bios now */
 904
 905         bitmap_startwrite(bitmap, bio->bi_sector, r1_bio->sectors,
 906                                 test_bit(R1BIO_BehindIO, &r1_bio->state));
 907         spin_lock_irqsave(&conf->device_lock, flags);
 908         bio_list_merge(&conf->pending_bio_list, &bl);
 909         bio_list_init(&bl);
 910
 911         blk_plug_device(mddev->queue);
 912         spin_unlock_irqrestore(&conf->device_lock, flags);
 913
 914 #if 0
 915         while ((bio = bio_list_pop(&bl)) != NULL)
 916                 generic_make_request(bio);
 917 #endif
 918
 919         return 0;
 920 }
 921
 922 static void status(struct seq_file *seq, mddev_t *mddev)
 923 {
 924         conf_t *conf = mddev_to_conf(mddev);
 925         int i;
 926
 927         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 928                                                 conf->working_disks);
 929         for (i = 0; i < conf->raid_disks; i++)
 930                 seq_printf(seq, "%s",
 931                               conf->mirrors[i].rdev &&
 932                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
 933         seq_printf(seq, "]");
 934 }
 935
 936
 937 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 938 {
 939         char b[BDEVNAME_SIZE];
 940         conf_t *conf = mddev_to_conf(mddev);
 941
 942         /*
 943          * If it is not operational, then we have already marked it as dead
 944          * else if it is the last working disks, ignore the error, let the
 945          * next level up know.
 946          * else mark the drive as failed
 947          */
 948         if (test_bit(In_sync, &rdev->flags)
 949             && conf->working_disks == 1)
 950                 /*
 951                  * Don't fail the drive, act as though we were just a
 952                  * normal single drive
 953                  */
 954                 return;
 955         if (test_bit(In_sync, &rdev->flags)) {
 956                 mddev->degraded++;
 957                 conf->working_disks--;
 958                 /*
 959                  * if recovery is running, make sure it aborts.
 960                  */
 961                 set_bit(MD_RECOVERY_ERR, &mddev->recovery);
 962         }
 963         clear_bit(In_sync, &rdev->flags);
 964         set_bit(Faulty, &rdev->flags);
 965         mddev->sb_dirty = 1;
 966         printk(KERN_ALERT "raid1: Disk failure on %s, disabling device. \n"
 967                 "       Operation continuing on %d devices\n",
 968                 bdevname(rdev->bdev,b), conf->working_disks);
 969 }
 970
 971 static void print_conf(conf_t *conf)
 972 {
 973         int i;
 974         mirror_info_t *tmp;
 975
 976         printk("RAID1 conf printout:\n");
 977         if (!conf) {
 978                 printk("(!conf)\n");
 979                 return;
 980         }
 981         printk(" --- wd:%d rd:%d\n", conf->working_disks,
 982                 conf->raid_disks);
 983
 984         for (i = 0; i < conf->raid_disks; i++) {
 985                 char b[BDEVNAME_SIZE];
 986                 tmp = conf->mirrors + i;
 987                 if (tmp->rdev)
 988                         printk(" disk %d, wo:%d, o:%d, dev:%s\n",
 989                                 i, !test_bit(In_sync, &tmp->rdev->flags), !test_bit(Faulty, &tmp->rdev->flags),
 990                                 bdevname(tmp->rdev->bdev,b));
 991         }
 992 }
 993
 994 static void close_sync(conf_t *conf)
 995 {
 996         wait_barrier(conf);
 997         allow_barrier(conf);
 998
 999         mempool_destroy(conf->r1buf_pool);
1000         conf->r1buf_pool = NULL;
1001 }
1002
1003 static int raid1_spare_active(mddev_t *mddev)
1004 {
1005         int i;
1006         conf_t *conf = mddev->private;
1007         mirror_info_t *tmp;
1008
1009         /*
1010          * Find all failed disks within the RAID1 configuration
1011          * and mark them readable
1012          */
1013         for (i = 0; i < conf->raid_disks; i++) {
1014                 tmp = conf->mirrors + i;
1015                 if (tmp->rdev
1016                     && !test_bit(Faulty, &tmp->rdev->flags)
1017                     && !test_bit(In_sync, &tmp->rdev->flags)) {
1018                         conf->working_disks++;
1019                         mddev->degraded--;
1020                         set_bit(In_sync, &tmp->rdev->flags);
1021                 }
1022         }
1023
1024         print_conf(conf);
1025         return 0;
1026 }
1027
1028
1029 static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1030 {
1031         conf_t *conf = mddev->private;
1032         int found = 0;
1033         int mirror = 0;
1034         mirror_info_t *p;
1035
1036         for (mirror=0; mirror < mddev->raid_disks; mirror++)
1037                 if ( !(p=conf->mirrors+mirror)->rdev) {
1038
1039                         blk_queue_stack_limits(mddev->queue,
1040                                                rdev->bdev->bd_disk->queue);
1041                         /* as we don't honour merge_bvec_fn, we must never risk
1042                          * violating it, so limit ->max_sector to one PAGE, as
1043                          * a one page request is never in violation.
1044                          */
1045                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1046                             mddev->queue->max_sectors > (PAGE_SIZE>>9))
1047                                 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
1048
1049                         p->head_position = 0;
1050                         rdev->raid_disk = mirror;
1051                         found = 1;
1052                         /* As all devices are equivalent, we don't need a full recovery
1053                          * if this was recently any drive of the array
1054                          */
1055                         if (rdev->saved_raid_disk < 0)
1056                                 conf->fullsync = 1;
1057                         rcu_assign_pointer(p->rdev, rdev);
1058                         break;
1059                 }
1060
1061         print_conf(conf);
1062         return found;
1063 }
1064
1065 static int raid1_remove_disk(mddev_t *mddev, int number)
1066 {
1067         conf_t *conf = mddev->private;
1068         int err = 0;
1069         mdk_rdev_t *rdev;
1070         mirror_info_t *p = conf->mirrors+ number;
1071
1072         print_conf(conf);
1073         rdev = p->rdev;
1074         if (rdev) {
1075                 if (test_bit(In_sync, &rdev->flags) ||
1076                     atomic_read(&rdev->nr_pending)) {
1077                         err = -EBUSY;
1078                         goto abort;
1079                 }
1080                 p->rdev = NULL;
1081                 synchronize_rcu();
1082                 if (atomic_read(&rdev->nr_pending)) {
1083                         /* lost the race, try later */
1084                         err = -EBUSY;
1085                         p->rdev = rdev;
1086                 }
1087         }
1088 abort:
1089
1090         print_conf(conf);
1091         return err;
1092 }
1093
1094
1095 static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error)
1096 {
1097         r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
1098         int i;
1099
1100         if (bio->bi_size)
1101                 return 1;
1102
1103         for (i=r1_bio->mddev->raid_disks; i--; )
1104                 if (r1_bio->bios[i] == bio)
1105                         break;
1106         BUG_ON(i < 0);
1107         update_head_pos(i, r1_bio);
1108         /*
1109          * we have read a block, now it needs to be re-written,
1110          * or re-read if the read failed.
1111          * We don't do much here, just schedule handling by raid1d
1112          */
1113         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1114                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1115
1116         if (atomic_dec_and_test(&r1_bio->remaining))
1117                 reschedule_retry(r1_bio);
1118         return 0;
1119 }
1120
1121 static int end_sync_write(struct bio *bio, unsigned int bytes_done, int error)
1122 {
1123         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1124         r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
1125         mddev_t *mddev = r1_bio->mddev;
1126         conf_t *conf = mddev_to_conf(mddev);
1127         int i;
1128         int mirror=0;
1129
1130         if (bio->bi_size)
1131                 return 1;
1132
1133         for (i = 0; i < conf->raid_disks; i++)
1134                 if (r1_bio->bios[i] == bio) {
1135                         mirror = i;
1136                         break;
1137                 }
1138         if (!uptodate)
1139                 md_error(mddev, conf->mirrors[mirror].rdev);
1140
1141         update_head_pos(mirror, r1_bio);
1142
1143         if (atomic_dec_and_test(&r1_bio->remaining)) {
1144                 md_done_sync(mddev, r1_bio->sectors, uptodate);
1145                 put_buf(r1_bio);
1146         }
1147         return 0;
1148 }
1149
1150 static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
1151 {
1152         conf_t *conf = mddev_to_conf(mddev);
1153         int i;
1154         int disks = conf->raid_disks;
1155         struct bio *bio, *wbio;
1156
1157         bio = r1_bio->bios[r1_bio->read_disk];
1158
1159
1160         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1161                 /* We have read all readable devices.  If we haven't
1162                  * got the block, then there is no hope left.
1163                  * If we have, then we want to do a comparison
1164                  * and skip the write if everything is the same.
1165                  * If any blocks failed to read, then we need to
1166                  * attempt an over-write
1167                  */
1168                 int primary;
1169                 if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
1170                         for (i=0; i<mddev->raid_disks; i++)
1171                                 if (r1_bio->bios[i]->bi_end_io == end_sync_read)
1172                                         md_error(mddev, conf->mirrors[i].rdev);
1173
1174                         md_done_sync(mddev, r1_bio->sectors, 1);
1175                         put_buf(r1_bio);
1176                         return;
1177                 }
1178                 for (primary=0; primary<mddev->raid_disks; primary++)
1179                         if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
1180                             test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
1181                                 r1_bio->bios[primary]->bi_end_io = NULL;
1182                                 rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
1183                                 break;
1184                         }
1185                 r1_bio->read_disk = primary;
1186                 for (i=0; i<mddev->raid_disks; i++)
1187                         if (r1_bio->bios[i]->bi_end_io == end_sync_read &&
1188                             test_bit(BIO_UPTODATE, &r1_bio->bios[i]->bi_flags)) {
1189                                 int j;
1190                                 int vcnt = r1_bio->sectors >> (PAGE_SHIFT- 9);
1191                                 struct bio *pbio = r1_bio->bios[primary];
1192                                 struct bio *sbio = r1_bio->bios[i];
1193                                 for (j = vcnt; j-- ; )
1194                                         if (memcmp(page_address(pbio->bi_io_vec[j].bv_page),
1195                                                    page_address(sbio->bi_io_vec[j].bv_page),
1196                                                    PAGE_SIZE))
1197                                                 break;
1198                                 if (j >= 0)
1199                                         mddev->resync_mismatches += r1_bio->sectors;
1200                                 if (j < 0 || test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
1201                                         sbio->bi_end_io = NULL;
1202                                         rdev_dec_pending(conf->mirrors[i].rdev, mddev);
1203                                 } else {
1204                                         /* fixup the bio for reuse */
1205                                         sbio->bi_vcnt = vcnt;
1206                                         sbio->bi_size = r1_bio->sectors << 9;
1207                                         sbio->bi_idx = 0;
1208                                         sbio->bi_phys_segments = 0;
1209                                         sbio->bi_hw_segments = 0;
1210                                         sbio->bi_hw_front_size = 0;
1211                                         sbio->bi_hw_back_size = 0;
1212                                         sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1213                                         sbio->bi_flags |= 1 << BIO_UPTODATE;
1214                                         sbio->bi_next = NULL;
1215                                         sbio->bi_sector = r1_bio->sector +
1216                                                 conf->mirrors[i].rdev->data_offset;
1217                                         sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
1218                                 }
1219                         }
1220         }
1221         if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
1222                 /* ouch - failed to read all of that.
1223                  * Try some synchronous reads of other devices to get
1224                  * good data, much like with normal read errors.  Only
1225                  * read into the pages we already have so they we don't
1226                  * need to re-issue the read request.
1227                  * We don't need to freeze the array, because being in an
1228                  * active sync request, there is no normal IO, and
1229                  * no overlapping syncs.
1230                  */
1231                 sector_t sect = r1_bio->sector;
1232                 int sectors = r1_bio->sectors;
1233                 int idx = 0;
1234
1235                 while(sectors) {
1236                         int s = sectors;
1237                         int d = r1_bio->read_disk;
1238                         int success = 0;
1239                         mdk_rdev_t *rdev;
1240
1241                         if (s > (PAGE_SIZE>>9))
1242                                 s = PAGE_SIZE >> 9;
1243                         do {
1244                                 if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
1245                                         rdev = conf->mirrors[d].rdev;
1246                                         if (sync_page_io(rdev->bdev,
1247                                                          sect + rdev->data_offset,
1248                                                          s<<9,
1249                                                          bio->bi_io_vec[idx].bv_page,
1250                                                          READ)) {
1251                                                 success = 1;
1252                                                 break;
1253                                         }
1254                                 }
1255                                 d++;
1256                                 if (d == conf->raid_disks)
1257                                         d = 0;
1258                         } while (!success && d != r1_bio->read_disk);
1259
1260                         if (success) {
1261                                 int start = d;
1262                                 /* write it back and re-read */
1263                                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1264                                 while (d != r1_bio->read_disk) {
1265                                         if (d == 0)
1266                                                 d = conf->raid_disks;
1267                                         d--;
1268                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1269                                                 continue;
1270                                         rdev = conf->mirrors[d].rdev;
1271                                         atomic_add(s, &rdev->corrected_errors);
1272                                         if (sync_page_io(rdev->bdev,
1273                                                          sect + rdev->data_offset,
1274                                                          s<<9,
1275                                                          bio->bi_io_vec[idx].bv_page,
1276                                                          WRITE) == 0)
1277                                                 md_error(mddev, rdev);
1278                                 }
1279                                 d = start;
1280                                 while (d != r1_bio->read_disk) {
1281                                         if (d == 0)
1282                                                 d = conf->raid_disks;
1283                                         d--;
1284                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1285                                                 continue;
1286                                         rdev = conf->mirrors[d].rdev;
1287                                         if (sync_page_io(rdev->bdev,
1288                                                          sect + rdev->data_offset,
1289                                                          s<<9,
1290                                                          bio->bi_io_vec[idx].bv_page,
1291                                                          READ) == 0)
1292                                                 md_error(mddev, rdev);
1293                                 }
1294                         } else {
1295                                 char b[BDEVNAME_SIZE];
1296                                 /* Cannot read from anywhere, array is toast */
1297                                 md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
1298                                 printk(KERN_ALERT "raid1: %s: unrecoverable I/O read error"
1299                                        " for block %llu\n",
1300                                        bdevname(bio->bi_bdev,b),
1301                                        (unsigned long long)r1_bio->sector);
1302                                 md_done_sync(mddev, r1_bio->sectors, 0);
1303                                 put_buf(r1_bio);
1304                                 return;
1305                         }
1306                         sectors -= s;
1307                         sect += s;
1308                         idx ++;
1309                 }
1310         }
1311
1312         /*
1313          * schedule writes
1314          */
1315         atomic_set(&r1_bio->remaining, 1);
1316         for (i = 0; i < disks ; i++) {
1317                 wbio = r1_bio->bios[i];
1318                 if (wbio->bi_end_io == NULL ||
1319                     (wbio->bi_end_io == end_sync_read &&
1320                      (i == r1_bio->read_disk ||
1321                       !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
1322                         continue;
1323
1324                 wbio->bi_rw = WRITE;
1325                 wbio->bi_end_io = end_sync_write;
1326                 atomic_inc(&r1_bio->remaining);
1327                 md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
1328
1329                 generic_make_request(wbio);
1330         }
1331
1332         if (atomic_dec_and_test(&r1_bio->remaining)) {
1333                 /* if we're here, all write(s) have completed, so clean up */
1334                 md_done_sync(mddev, r1_bio->sectors, 1);
1335                 put_buf(r1_bio);
1336         }
1337 }
1338
1339 /*
1340  * This is a kernel thread which:
1341  *
1342  *      1.      Retries failed read operations on working mirrors.
1343  *      2.      Updates the raid superblock when problems encounter.
1344  *      3.      Performs writes following reads for array syncronising.
1345  */
1346
1347 static void raid1d(mddev_t *mddev)
1348 {
1349         r1bio_t *r1_bio;
1350         struct bio *bio;
1351         unsigned long flags;
1352         conf_t *conf = mddev_to_conf(mddev);
1353         struct list_head *head = &conf->retry_list;
1354         int unplug=0;
1355         mdk_rdev_t *rdev;
1356
1357         md_check_recovery(mddev);
1358
1359         for (;;) {
1360                 char b[BDEVNAME_SIZE];
1361                 spin_lock_irqsave(&conf->device_lock, flags);
1362
1363                 if (conf->pending_bio_list.head) {
1364                         bio = bio_list_get(&conf->pending_bio_list);
1365                         blk_remove_plug(mddev->queue);
1366                         spin_unlock_irqrestore(&conf->device_lock, flags);
1367                         /* flush any pending bitmap writes to disk before proceeding w/ I/O */
1368                         if (bitmap_unplug(mddev->bitmap) != 0)
1369                                 printk("%s: bitmap file write failed!\n", mdname(mddev));
1370
1371                         while (bio) { /* submit pending writes */
1372                                 struct bio *next = bio->bi_next;
1373                                 bio->bi_next = NULL;
1374                                 generic_make_request(bio);
1375                                 bio = next;
1376                         }
1377                         unplug = 1;
1378
1379                         continue;
1380                 }
1381
1382                 if (list_empty(head))
1383                         break;
1384                 r1_bio = list_entry(head->prev, r1bio_t, retry_list);
1385                 list_del(head->prev);
1386                 conf->nr_queued--;
1387                 spin_unlock_irqrestore(&conf->device_lock, flags);
1388
1389                 mddev = r1_bio->mddev;
1390                 conf = mddev_to_conf(mddev);
1391                 if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
1392                         sync_request_write(mddev, r1_bio);
1393                         unplug = 1;
1394                 } else if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
1395                         /* some requests in the r1bio were BIO_RW_BARRIER
1396                          * requests which failed with -ENOTSUPP.  Hohumm..
1397                          * Better resubmit without the barrier.
1398                          * We know which devices to resubmit for, because
1399                          * all others have had their bios[] entry cleared.
1400                          */
1401                         int i;
1402                         clear_bit(R1BIO_BarrierRetry, &r1_bio->state);
1403                         clear_bit(R1BIO_Barrier, &r1_bio->state);
1404                         for (i=0; i < conf->raid_disks; i++)
1405                                 if (r1_bio->bios[i]) {
1406                                         struct bio_vec *bvec;
1407                                         int j;
1408
1409                                         bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
1410                                         /* copy pages from the failed bio, as
1411                                          * this might be a write-behind device */
1412                                         __bio_for_each_segment(bvec, bio, j, 0)
1413                                                 bvec->bv_page = bio_iovec_idx(r1_bio->bios[i], j)->bv_page;
1414                                         bio_put(r1_bio->bios[i]);
1415                                         bio->bi_sector = r1_bio->sector +
1416                                                 conf->mirrors[i].rdev->data_offset;
1417                                         bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1418                                         bio->bi_end_io = raid1_end_write_request;
1419                                         bio->bi_rw = WRITE;
1420                                         bio->bi_private = r1_bio;
1421                                         r1_bio->bios[i] = bio;
1422                                         generic_make_request(bio);
1423                                 }
1424                 } else {
1425                         int disk;
1426
1427                         /* we got a read error. Maybe the drive is bad.  Maybe just
1428                          * the block and we can fix it.
1429                          * We freeze all other IO, and try reading the block from
1430                          * other devices.  When we find one, we re-write
1431                          * and check it that fixes the read error.
1432                          * This is all done synchronously while the array is
1433                          * frozen
1434                          */
1435                         sector_t sect = r1_bio->sector;
1436                         int sectors = r1_bio->sectors;
1437                         freeze_array(conf);
1438                         if (mddev->ro == 0) while(sectors) {
1439                                 int s = sectors;
1440                                 int d = r1_bio->read_disk;
1441                                 int success = 0;
1442
1443                                 if (s > (PAGE_SIZE>>9))
1444                                         s = PAGE_SIZE >> 9;
1445
1446                                 do {
1447                                         rdev = conf->mirrors[d].rdev;
1448                                         if (rdev &&
1449                                             test_bit(In_sync, &rdev->flags) &&
1450                                             sync_page_io(rdev->bdev,
1451                                                          sect + rdev->data_offset,
1452                                                          s<<9,
1453                                                          conf->tmppage, READ))
1454                                                 success = 1;
1455                                         else {
1456                                                 d++;
1457                                                 if (d == conf->raid_disks)
1458                                                         d = 0;
1459                                         }
1460                                 } while (!success && d != r1_bio->read_disk);
1461
1462                                 if (success) {
1463                                         /* write it back and re-read */
1464                                         int start = d;
1465                                         while (d != r1_bio->read_disk) {
1466                                                 if (d==0)
1467                                                         d = conf->raid_disks;
1468                                                 d--;
1469                                                 rdev = conf->mirrors[d].rdev;
1470                                                 if (rdev &&
1471                                                     test_bit(In_sync, &rdev->flags)) {
1472                                                         if (sync_page_io(rdev->bdev,
1473                                                                          sect + rdev->data_offset,
1474                                                                          s<<9, conf->tmppage, WRITE) == 0)
1475                                                                 /* Well, this device is dead */
1476                                                                 md_error(mddev, rdev);
1477                                                 }
1478                                         }
1479                                         d = start;
1480                                         while (d != r1_bio->read_disk) {
1481                                                 if (d==0)
1482                                                         d = conf->raid_disks;
1483                                                 d--;
1484                                                 rdev = conf->mirrors[d].rdev;
1485                                                 if (rdev &&
1486                                                     test_bit(In_sync, &rdev->flags)) {
1487                                                         if (sync_page_io(rdev->bdev,
1488                                                                          sect + rdev->data_offset,
1489                                                                          s<<9, conf->tmppage, READ) == 0)
1490                                                                 /* Well, this device is dead */
1491                                                                 md_error(mddev, rdev);
1492                                                         else
1493                                                                 atomic_add(s, &rdev->corrected_errors);
1494
1495                                                 }
1496                                         }
1497                                 } else {
1498                                         /* Cannot read from anywhere -- bye bye array */
1499                                         md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
1500                                         break;
1501                                 }
1502                                 sectors -= s;
1503                                 sect += s;
1504                         }
1505
1506                         unfreeze_array(conf);
1507
1508                         bio = r1_bio->bios[r1_bio->read_disk];
1509                         if ((disk=read_balance(conf, r1_bio)) == -1) {
1510                                 printk(KERN_ALERT "raid1: %s: unrecoverable I/O"
1511                                        " read error for block %llu\n",
1512                                        bdevname(bio->bi_bdev,b),
1513                                        (unsigned long long)r1_bio->sector);
1514                                 raid_end_bio_io(r1_bio);
1515                         } else {
1516                                 r1_bio->bios[r1_bio->read_disk] =
1517                                         mddev->ro ? IO_BLOCKED : NULL;
1518                                 r1_bio->read_disk = disk;
1519                                 bio_put(bio);
1520                                 bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
1521                                 r1_bio->bios[r1_bio->read_disk] = bio;
1522                                 rdev = conf->mirrors[disk].rdev;
1523                                 if (printk_ratelimit())
1524                                         printk(KERN_ERR "raid1: %s: redirecting sector %llu to"
1525                                                " another mirror\n",
1526                                                bdevname(rdev->bdev,b),
1527                                                (unsigned long long)r1_bio->sector);
1528                                 bio->bi_sector = r1_bio->sector + rdev->data_offset;
1529                                 bio->bi_bdev = rdev->bdev;
1530                                 bio->bi_end_io = raid1_end_read_request;
1531                                 bio->bi_rw = READ;
1532                                 bio->bi_private = r1_bio;
1533                                 unplug = 1;
1534                                 generic_make_request(bio);
1535                         }
1536                 }
1537         }
1538         spin_unlock_irqrestore(&conf->device_lock, flags);
1539         if (unplug)
1540                 unplug_slaves(mddev);
1541 }
1542
1543
1544 static int init_resync(conf_t *conf)
1545 {
1546         int buffs;
1547
1548         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1549         if (conf->r1buf_pool)
1550                 BUG();
1551         conf->r1buf_pool = mempool_create(buffs, r1buf_pool_alloc, r1buf_pool_free,
1552                                           conf->poolinfo);
1553         if (!conf->r1buf_pool)
1554                 return -ENOMEM;
1555         conf->next_resync = 0;
1556         return 0;
1557 }
1558
1559 /*
1560  * perform a "sync" on one "block"
1561  *
1562  * We need to make sure that no normal I/O request - particularly write
1563  * requests - conflict with active sync requests.
1564  *
1565  * This is achieved by tracking pending requests and a 'barrier' concept
1566  * that can be installed to exclude normal IO requests.
1567  */
1568
1569 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1570 {
1571         conf_t *conf = mddev_to_conf(mddev);
1572         r1bio_t *r1_bio;
1573         struct bio *bio;
1574         sector_t max_sector, nr_sectors;
1575         int disk = -1;
1576         int i;
1577         int wonly = -1;
1578         int write_targets = 0, read_targets = 0;
1579         int sync_blocks;
1580         int still_degraded = 0;
1581
1582         if (!conf->r1buf_pool)
1583         {
1584 /*
1585                 printk("sync start - bitmap %p\n", mddev->bitmap);
1586 */
1587                 if (init_resync(conf))
1588                         return 0;
1589         }
1590
1591         max_sector = mddev->size << 1;
1592         if (sector_nr >= max_sector) {
1593                 /* If we aborted, we need to abort the
1594                  * sync on the 'current' bitmap chunk (there will
1595                  * only be one in raid1 resync.
1596                  * We can find the current addess in mddev->curr_resync
1597                  */
1598                 if (mddev->curr_resync < max_sector) /* aborted */
1599                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1600                                                 &sync_blocks, 1);
1601                 else /* completed sync */
1602                         conf->fullsync = 0;
1603
1604                 bitmap_close_sync(mddev->bitmap);
1605                 close_sync(conf);
1606                 return 0;
1607         }
1608
1609         /* before building a request, check if we can skip these blocks..
1610          * This call the bitmap_start_sync doesn't actually record anything
1611          */
1612         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1613             !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1614                 /* We can skip this block, and probably several more */
1615                 *skipped = 1;
1616                 return sync_blocks;
1617         }
1618         /*
1619          * If there is non-resync activity waiting for a turn,
1620          * and resync is going fast enough,
1621          * then let it though before starting on this new sync request.
1622          */
1623         if (!go_faster && conf->nr_waiting)
1624                 msleep_interruptible(1000);
1625
1626         raise_barrier(conf);
1627
1628         conf->next_resync = sector_nr;
1629
1630         r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
1631         rcu_read_lock();
1632         /*
1633          * If we get a correctably read error during resync or recovery,
1634          * we might want to read from a different device.  So we
1635          * flag all drives that could conceivably be read from for READ,
1636          * and any others (which will be non-In_sync devices) for WRITE.
1637          * If a read fails, we try reading from something else for which READ
1638          * is OK.
1639          */
1640
1641         r1_bio->mddev = mddev;
1642         r1_bio->sector = sector_nr;
1643         r1_bio->state = 0;
1644         set_bit(R1BIO_IsSync, &r1_bio->state);
1645
1646         for (i=0; i < conf->raid_disks; i++) {
1647                 mdk_rdev_t *rdev;
1648                 bio = r1_bio->bios[i];
1649
1650                 /* take from bio_init */
1651                 bio->bi_next = NULL;
1652                 bio->bi_flags |= 1 << BIO_UPTODATE;
1653                 bio->bi_rw = 0;
1654                 bio->bi_vcnt = 0;
1655                 bio->bi_idx = 0;
1656                 bio->bi_phys_segments = 0;
1657                 bio->bi_hw_segments = 0;
1658                 bio->bi_size = 0;
1659                 bio->bi_end_io = NULL;
1660                 bio->bi_private = NULL;
1661
1662                 rdev = rcu_dereference(conf->mirrors[i].rdev);
1663                 if (rdev == NULL ||
1664                            test_bit(Faulty, &rdev->flags)) {
1665                         still_degraded = 1;
1666                         continue;
1667                 } else if (!test_bit(In_sync, &rdev->flags)) {
1668                         bio->bi_rw = WRITE;
1669                         bio->bi_end_io = end_sync_write;
1670                         write_targets ++;
1671                 } else {
1672                         /* may need to read from here */
1673                         bio->bi_rw = READ;
1674                         bio->bi_end_io = end_sync_read;
1675                         if (test_bit(WriteMostly, &rdev->flags)) {
1676                                 if (wonly < 0)
1677                                         wonly = i;
1678                         } else {
1679                                 if (disk < 0)
1680                                         disk = i;
1681                         }
1682                         read_targets++;
1683                 }
1684                 atomic_inc(&rdev->nr_pending);
1685                 bio->bi_sector = sector_nr + rdev->data_offset;
1686                 bio->bi_bdev = rdev->bdev;
1687                 bio->bi_private = r1_bio;
1688         }
1689         rcu_read_unlock();
1690         if (disk < 0)
1691                 disk = wonly;
1692         r1_bio->read_disk = disk;
1693
1694         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
1695                 /* extra read targets are also write targets */
1696                 write_targets += read_targets-1;
1697
1698         if (write_targets == 0 || read_targets == 0) {
1699                 /* There is nowhere to write, so all non-sync
1700                  * drives must be failed - so we are finished
1701                  */
1702                 sector_t rv = max_sector - sector_nr;
1703                 *skipped = 1;
1704                 put_buf(r1_bio);
1705                 return rv;
1706         }
1707
1708         nr_sectors = 0;
1709         sync_blocks = 0;
1710         do {
1711                 struct page *page;
1712                 int len = PAGE_SIZE;
1713                 if (sector_nr + (len>>9) > max_sector)
1714                         len = (max_sector - sector_nr) << 9;
1715                 if (len == 0)
1716                         break;
1717                 if (sync_blocks == 0) {
1718                         if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1719                                                &sync_blocks, still_degraded) &&
1720                             !conf->fullsync &&
1721                             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
1722                                 break;
1723                         if (sync_blocks < (PAGE_SIZE>>9))
1724                                 BUG();
1725                         if (len > (sync_blocks<<9))
1726                                 len = sync_blocks<<9;
1727                 }
1728
1729                 for (i=0 ; i < conf->raid_disks; i++) {
1730                         bio = r1_bio->bios[i];
1731                         if (bio->bi_end_io) {
1732                                 page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
1733                                 if (bio_add_page(bio, page, len, 0) == 0) {
1734                                         /* stop here */
1735                                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
1736                                         while (i > 0) {
1737                                                 i--;
1738                                                 bio = r1_bio->bios[i];
1739                                                 if (bio->bi_end_io==NULL)
1740                                                         continue;
1741                                                 /* remove last page from this bio */
1742                                                 bio->bi_vcnt--;
1743                                                 bio->bi_size -= len;
1744                                                 bio->bi_flags &= ~(1<< BIO_SEG_VALID);
1745                                         }
1746                                         goto bio_full;
1747                                 }
1748                         }
1749                 }
1750                 nr_sectors += len>>9;
1751                 sector_nr += len>>9;
1752                 sync_blocks -= (len>>9);
1753         } while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
1754  bio_full:
1755         r1_bio->sectors = nr_sectors;
1756
1757         /* For a user-requested sync, we read all readable devices and do a
1758          * compare
1759          */
1760         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1761                 atomic_set(&r1_bio->remaining, read_targets);
1762                 for (i=0; i<conf->raid_disks; i++) {
1763                         bio = r1_bio->bios[i];
1764                         if (bio->bi_end_io == end_sync_read) {
1765                                 md_sync_acct(conf->mirrors[i].rdev->bdev, nr_sectors);
1766                                 generic_make_request(bio);
1767                         }
1768                 }
1769         } else {
1770                 atomic_set(&r1_bio->remaining, 1);
1771                 bio = r1_bio->bios[r1_bio->read_disk];
1772                 md_sync_acct(conf->mirrors[r1_bio->read_disk].rdev->bdev,
1773                              nr_sectors);
1774                 generic_make_request(bio);
1775
1776         }
1777
1778         return nr_sectors;
1779 }
1780
1781 static int run(mddev_t *mddev)
1782 {
1783         conf_t *conf;
1784         int i, j, disk_idx;
1785         mirror_info_t *disk;
1786         mdk_rdev_t *rdev;
1787         struct list_head *tmp;
1788
1789         if (mddev->level != 1) {
1790                 printk("raid1: %s: raid level not set to mirroring (%d)\n",
1791                        mdname(mddev), mddev->level);
1792                 goto out;
1793         }
1794         /*
1795          * copy the already verified devices into our private RAID1
1796          * bookkeeping area. [whatever we allocate in run(),
1797          * should be freed in stop()]
1798          */
1799         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
1800         mddev->private = conf;
1801         if (!conf)
1802                 goto out_no_mem;
1803
1804         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
1805                                  GFP_KERNEL);
1806         if (!conf->mirrors)
1807                 goto out_no_mem;
1808
1809         conf->tmppage = alloc_page(GFP_KERNEL);
1810         if (!conf->tmppage)
1811                 goto out_no_mem;
1812
1813         conf->poolinfo = kmalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
1814         if (!conf->poolinfo)
1815                 goto out_no_mem;
1816         conf->poolinfo->mddev = mddev;
1817         conf->poolinfo->raid_disks = mddev->raid_disks;
1818         conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
1819                                           r1bio_pool_free,
1820                                           conf->poolinfo);
1821         if (!conf->r1bio_pool)
1822                 goto out_no_mem;
1823
1824         ITERATE_RDEV(mddev, rdev, tmp) {
1825                 disk_idx = rdev->raid_disk;
1826                 if (disk_idx >= mddev->raid_disks
1827                     || disk_idx < 0)
1828                         continue;
1829                 disk = conf->mirrors + disk_idx;
1830
1831                 disk->rdev = rdev;
1832
1833                 blk_queue_stack_limits(mddev->queue,
1834                                        rdev->bdev->bd_disk->queue);
1835                 /* as we don't honour merge_bvec_fn, we must never risk
1836                  * violating it, so limit ->max_sector to one PAGE, as
1837                  * a one page request is never in violation.
1838                  */
1839                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1840                     mddev->queue->max_sectors > (PAGE_SIZE>>9))
1841                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
1842
1843                 disk->head_position = 0;
1844                 if (!test_bit(Faulty, &rdev->flags) && test_bit(In_sync, &rdev->flags))
1845                         conf->working_disks++;
1846         }
1847         conf->raid_disks = mddev->raid_disks;
1848         conf->mddev = mddev;
1849         spin_lock_init(&conf->device_lock);
1850         INIT_LIST_HEAD(&conf->retry_list);
1851         if (conf->working_disks == 1)
1852                 mddev->recovery_cp = MaxSector;
1853
1854         spin_lock_init(&conf->resync_lock);
1855         init_waitqueue_head(&conf->wait_barrier);
1856
1857         bio_list_init(&conf->pending_bio_list);
1858         bio_list_init(&conf->flushing_bio_list);
1859
1860         if (!conf->working_disks) {
1861                 printk(KERN_ERR "raid1: no operational mirrors for %s\n",
1862                         mdname(mddev));
1863                 goto out_free_conf;
1864         }
1865
1866         mddev->degraded = 0;
1867         for (i = 0; i < conf->raid_disks; i++) {
1868
1869                 disk = conf->mirrors + i;
1870
1871                 if (!disk->rdev) {
1872                         disk->head_position = 0;
1873                         mddev->degraded++;
1874                 }
1875         }
1876
1877         /*
1878          * find the first working one and use it as a starting point
1879          * to read balancing.
1880          */
1881         for (j = 0; j < conf->raid_disks &&
1882                      (!conf->mirrors[j].rdev ||
1883                       !test_bit(In_sync, &conf->mirrors[j].rdev->flags)) ; j++)
1884                 /* nothing */;
1885         conf->last_used = j;
1886
1887
1888         mddev->thread = md_register_thread(raid1d, mddev, "%s_raid1");
1889         if (!mddev->thread) {
1890                 printk(KERN_ERR
1891                        "raid1: couldn't allocate thread for %s\n",
1892                        mdname(mddev));
1893                 goto out_free_conf;
1894         }
1895
1896         printk(KERN_INFO
1897                 "raid1: raid set %s active with %d out of %d mirrors\n",
1898                 mdname(mddev), mddev->raid_disks - mddev->degraded,
1899                 mddev->raid_disks);
1900         /*
1901          * Ok, everything is just fine now
1902          */
1903         mddev->array_size = mddev->size;
1904
1905         mddev->queue->unplug_fn = raid1_unplug;
1906         mddev->queue->issue_flush_fn = raid1_issue_flush;
1907
1908         return 0;
1909
1910 out_no_mem:
1911         printk(KERN_ERR "raid1: couldn't allocate memory for %s\n",
1912                mdname(mddev));
1913
1914 out_free_conf:
1915         if (conf) {
1916                 if (conf->r1bio_pool)
1917                         mempool_destroy(conf->r1bio_pool);
1918                 kfree(conf->mirrors);
1919                 safe_put_page(conf->tmppage);
1920                 kfree(conf->poolinfo);
1921                 kfree(conf);
1922                 mddev->private = NULL;
1923         }
1924 out:
1925         return -EIO;
1926 }
1927
1928 static int stop(mddev_t *mddev)
1929 {
1930         conf_t *conf = mddev_to_conf(mddev);
1931         struct bitmap *bitmap = mddev->bitmap;
1932         int behind_wait = 0;
1933
1934         /* wait for behind writes to complete */
1935         while (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
1936                 behind_wait++;
1937                 printk(KERN_INFO "raid1: behind writes in progress on device %s, waiting to stop (%d)\n", mdname(mddev), behind_wait);
1938                 set_current_state(TASK_UNINTERRUPTIBLE);
1939                 schedule_timeout(HZ); /* wait a second */
1940                 /* need to kick something here to make sure I/O goes? */
1941         }
1942
1943         md_unregister_thread(mddev->thread);
1944         mddev->thread = NULL;
1945         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
1946         if (conf->r1bio_pool)
1947                 mempool_destroy(conf->r1bio_pool);
1948         kfree(conf->mirrors);
1949         kfree(conf->poolinfo);
1950         kfree(conf);
1951         mddev->private = NULL;
1952         return 0;
1953 }
1954
1955 static int raid1_resize(mddev_t *mddev, sector_t sectors)
1956 {
1957         /* no resync is happening, and there is enough space
1958          * on all devices, so we can resize.
1959          * We need to make sure resync covers any new space.
1960          * If the array is shrinking we should possibly wait until
1961          * any io in the removed space completes, but it hardly seems
1962          * worth it.
1963          */
1964         mddev->array_size = sectors>>1;
1965         set_capacity(mddev->gendisk, mddev->array_size << 1);
1966         mddev->changed = 1;
1967         if (mddev->array_size > mddev->size && mddev->recovery_cp == MaxSector) {
1968                 mddev->recovery_cp = mddev->size << 1;
1969                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
1970         }
1971         mddev->size = mddev->array_size;
1972         mddev->resync_max_sectors = sectors;
1973         return 0;
1974 }
1975
1976 static int raid1_reshape(mddev_t *mddev, int raid_disks)
1977 {
1978         /* We need to:
1979          * 1/ resize the r1bio_pool
1980          * 2/ resize conf->mirrors
1981          *
1982          * We allocate a new r1bio_pool if we can.
1983          * Then raise a device barrier and wait until all IO stops.
1984          * Then resize conf->mirrors and swap in the new r1bio pool.
1985          *
1986          * At the same time, we "pack" the devices so that all the missing
1987          * devices have the higher raid_disk numbers.
1988          */
1989         mempool_t *newpool, *oldpool;
1990         struct pool_info *newpoolinfo;
1991         mirror_info_t *newmirrors;
1992         conf_t *conf = mddev_to_conf(mddev);
1993         int cnt;
1994
1995         int d, d2;
1996
1997         if (raid_disks < conf->raid_disks) {
1998                 cnt=0;
1999                 for (d= 0; d < conf->raid_disks; d++)
2000                         if (conf->mirrors[d].rdev)
2001                                 cnt++;
2002                 if (cnt > raid_disks)
2003                         return -EBUSY;
2004         }
2005
2006         newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
2007         if (!newpoolinfo)
2008                 return -ENOMEM;
2009         newpoolinfo->mddev = mddev;
2010         newpoolinfo->raid_disks = raid_disks;
2011
2012         newpool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2013                                  r1bio_pool_free, newpoolinfo);
2014         if (!newpool) {
2015                 kfree(newpoolinfo);
2016                 return -ENOMEM;
2017         }
2018         newmirrors = kzalloc(sizeof(struct mirror_info) * raid_disks, GFP_KERNEL);
2019         if (!newmirrors) {
2020                 kfree(newpoolinfo);
2021                 mempool_destroy(newpool);
2022                 return -ENOMEM;
2023         }
2024
2025         raise_barrier(conf);
2026
2027         /* ok, everything is stopped */
2028         oldpool = conf->r1bio_pool;
2029         conf->r1bio_pool = newpool;
2030
2031         for (d=d2=0; d < conf->raid_disks; d++)
2032                 if (conf->mirrors[d].rdev) {
2033                         conf->mirrors[d].rdev->raid_disk = d2;
2034                         newmirrors[d2++].rdev = conf->mirrors[d].rdev;
2035                 }
2036         kfree(conf->mirrors);
2037         conf->mirrors = newmirrors;
2038         kfree(conf->poolinfo);
2039         conf->poolinfo = newpoolinfo;
2040
2041         mddev->degraded += (raid_disks - conf->raid_disks);
2042         conf->raid_disks = mddev->raid_disks = raid_disks;
2043
2044         conf->last_used = 0; /* just make sure it is in-range */
2045         lower_barrier(conf);
2046
2047         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2048         md_wakeup_thread(mddev->thread);
2049
2050         mempool_destroy(oldpool);
2051         return 0;
2052 }
2053
2054 static void raid1_quiesce(mddev_t *mddev, int state)
2055 {
2056         conf_t *conf = mddev_to_conf(mddev);
2057
2058         switch(state) {
2059         case 1:
2060                 raise_barrier(conf);
2061                 break;
2062         case 0:
2063                 lower_barrier(conf);
2064                 break;
2065         }
2066 }
2067
2068
2069 static struct mdk_personality raid1_personality =
2070 {
2071         .name           = "raid1",
2072         .level          = 1,
2073         .owner          = THIS_MODULE,
2074         .make_request   = make_request,
2075         .run            = run,
2076         .stop           = stop,
2077         .status         = status,
2078         .error_handler  = error,
2079         .hot_add_disk   = raid1_add_disk,
2080         .hot_remove_disk= raid1_remove_disk,
2081         .spare_active   = raid1_spare_active,
2082         .sync_request   = sync_request,
2083         .resize         = raid1_resize,
2084         .reshape        = raid1_reshape,
2085         .quiesce        = raid1_quiesce,
2086 };
2087
2088 static int __init raid_init(void)
2089 {
2090         return register_md_personality(&raid1_personality);
2091 }
2092
2093 static void raid_exit(void)
2094 {
2095         unregister_md_personality(&raid1_personality);
2096 }
2097
2098 module_init(raid_init);
2099 module_exit(raid_exit);
2100 MODULE_LICENSE("GPL");
2101 MODULE_ALIAS("md-personality-3"); /* RAID1 */
2102 MODULE_ALIAS("md-raid1");
2103 MODULE_ALIAS("md-level-1");