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 == -EOPNOTSUPP && 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                 /* Don't rdev_dec_pending in this branch - keep it for the retry */
 323         } else {
 324                 /*
 325                  * this branch is our 'one mirror IO has finished' event handler:
 326                  */
 327                 r1_bio->bios[mirror] = NULL;
 328                 to_put = bio;
 329                 if (!uptodate) {
 330                         md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
 331                         /* an I/O failed, we can't clear the bitmap */
 332                         set_bit(R1BIO_Degraded, &r1_bio->state);
 333                 } else
 334                         /*
 335                          * Set R1BIO_Uptodate in our master bio, so that
 336                          * we will return a good error code for to the higher
 337                          * levels even if IO on some other mirrored buffer fails.
 338                          *
 339                          * The 'master' represents the composite IO operation to
 340                          * user-side. So if something waits for IO, then it will
 341                          * wait for the 'master' bio.
 342                          */
 343                         set_bit(R1BIO_Uptodate, &r1_bio->state);
 344
 345                 update_head_pos(mirror, r1_bio);
 346
 347                 if (behind) {
 348                         if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
 349                                 atomic_dec(&r1_bio->behind_remaining);
 350
 351                         /* In behind mode, we ACK the master bio once the I/O has safely
 352                          * reached all non-writemostly disks. Setting the Returned bit
 353                          * ensures that this gets done only once -- we don't ever want to
 354                          * return -EIO here, instead we'll wait */
 355
 356                         if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
 357                             test_bit(R1BIO_Uptodate, &r1_bio->state)) {
 358                                 /* Maybe we can return now */
 359                                 if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 360                                         struct bio *mbio = r1_bio->master_bio;
 361                                         PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
 362                                                (unsigned long long) mbio->bi_sector,
 363                                                (unsigned long long) mbio->bi_sector +
 364                                                (mbio->bi_size >> 9) - 1);
 365                                         bio_endio(mbio, mbio->bi_size, 0);
 366                                 }
 367                         }
 368                 }
 369                 rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 370         }
 371         /*
 372          *
 373          * Let's see if all mirrored write operations have finished
 374          * already.
 375          */
 376         if (atomic_dec_and_test(&r1_bio->remaining)) {
 377                 if (test_bit(R1BIO_BarrierRetry, &r1_bio->state))
 378                         reschedule_retry(r1_bio);
 379                 else {
 380                         /* it really is the end of this request */
 381                         if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
 382                                 /* free extra copy of the data pages */
 383                                 int i = bio->bi_vcnt;
 384                                 while (i--)
 385                                         safe_put_page(bio->bi_io_vec[i].bv_page);
 386                         }
 387                         /* clear the bitmap if all writes complete successfully */
 388                         bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
 389                                         r1_bio->sectors,
 390                                         !test_bit(R1BIO_Degraded, &r1_bio->state),
 391                                         behind);
 392                         md_write_end(r1_bio->mddev);
 393                         raid_end_bio_io(r1_bio);
 394                 }
 395         }
 396
 397         if (to_put)
 398                 bio_put(to_put);
 399
 400         return 0;
 401 }
 402
 403
 404 /*
 405  * This routine returns the disk from which the requested read should
 406  * be done. There is a per-array 'next expected sequential IO' sector
 407  * number - if this matches on the next IO then we use the last disk.
 408  * There is also a per-disk 'last know head position' sector that is
 409  * maintained from IRQ contexts, both the normal and the resync IO
 410  * completion handlers update this position correctly. If there is no
 411  * perfect sequential match then we pick the disk whose head is closest.
 412  *
 413  * If there are 2 mirrors in the same 2 devices, performance degrades
 414  * because position is mirror, not device based.
 415  *
 416  * The rdev for the device selected will have nr_pending incremented.
 417  */
 418 static int read_balance(conf_t *conf, r1bio_t *r1_bio)
 419 {
 420         const unsigned long this_sector = r1_bio->sector;
 421         int new_disk = conf->last_used, disk = new_disk;
 422         int wonly_disk = -1;
 423         const int sectors = r1_bio->sectors;
 424         sector_t new_distance, current_distance;
 425         mdk_rdev_t *rdev;
 426
 427         rcu_read_lock();
 428         /*
 429          * Check if we can balance. We can balance on the whole
 430          * device if no resync is going on, or below the resync window.
 431          * We take the first readable disk when above the resync window.
 432          */
 433  retry:
 434         if (conf->mddev->recovery_cp < MaxSector &&
 435             (this_sector + sectors >= conf->next_resync)) {
 436                 /* Choose the first operation device, for consistancy */
 437                 new_disk = 0;
 438
 439                 for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 440                      r1_bio->bios[new_disk] == IO_BLOCKED ||
 441                      !rdev || !test_bit(In_sync, &rdev->flags)
 442                              || test_bit(WriteMostly, &rdev->flags);
 443                      rdev = rcu_dereference(conf->mirrors[++new_disk].rdev)) {
 444
 445                         if (rdev && test_bit(In_sync, &rdev->flags) &&
 446                                 r1_bio->bios[new_disk] != IO_BLOCKED)
 447                                 wonly_disk = new_disk;
 448
 449                         if (new_disk == conf->raid_disks - 1) {
 450                                 new_disk = wonly_disk;
 451                                 break;
 452                         }
 453                 }
 454                 goto rb_out;
 455         }
 456
 457
 458         /* make sure the disk is operational */
 459         for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 460              r1_bio->bios[new_disk] == IO_BLOCKED ||
 461              !rdev || !test_bit(In_sync, &rdev->flags) ||
 462                      test_bit(WriteMostly, &rdev->flags);
 463              rdev = rcu_dereference(conf->mirrors[new_disk].rdev)) {
 464
 465                 if (rdev && test_bit(In_sync, &rdev->flags) &&
 466                     r1_bio->bios[new_disk] != IO_BLOCKED)
 467                         wonly_disk = new_disk;
 468
 469                 if (new_disk <= 0)
 470                         new_disk = conf->raid_disks;
 471                 new_disk--;
 472                 if (new_disk == disk) {
 473                         new_disk = wonly_disk;
 474                         break;
 475                 }
 476         }
 477
 478         if (new_disk < 0)
 479                 goto rb_out;
 480
 481         disk = new_disk;
 482         /* now disk == new_disk == starting point for search */
 483
 484         /*
 485          * Don't change to another disk for sequential reads:
 486          */
 487         if (conf->next_seq_sect == this_sector)
 488                 goto rb_out;
 489         if (this_sector == conf->mirrors[new_disk].head_position)
 490                 goto rb_out;
 491
 492         current_distance = abs(this_sector - conf->mirrors[disk].head_position);
 493
 494         /* Find the disk whose head is closest */
 495
 496         do {
 497                 if (disk <= 0)
 498                         disk = conf->raid_disks;
 499                 disk--;
 500
 501                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 502
 503                 if (!rdev || r1_bio->bios[disk] == IO_BLOCKED ||
 504                     !test_bit(In_sync, &rdev->flags) ||
 505                     test_bit(WriteMostly, &rdev->flags))
 506                         continue;
 507
 508                 if (!atomic_read(&rdev->nr_pending)) {
 509                         new_disk = disk;
 510                         break;
 511                 }
 512                 new_distance = abs(this_sector - conf->mirrors[disk].head_position);
 513                 if (new_distance < current_distance) {
 514                         current_distance = new_distance;
 515                         new_disk = disk;
 516                 }
 517         } while (disk != conf->last_used);
 518
 519  rb_out:
 520
 521
 522         if (new_disk >= 0) {
 523                 rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 524                 if (!rdev)
 525                         goto retry;
 526                 atomic_inc(&rdev->nr_pending);
 527                 if (!test_bit(In_sync, &rdev->flags)) {
 528                         /* cannot risk returning a device that failed
 529                          * before we inc'ed nr_pending
 530                          */
 531                         rdev_dec_pending(rdev, conf->mddev);
 532                         goto retry;
 533                 }
 534                 conf->next_seq_sect = this_sector + sectors;
 535                 conf->last_used = new_disk;
 536         }
 537         rcu_read_unlock();
 538
 539         return new_disk;
 540 }
 541
 542 static void unplug_slaves(mddev_t *mddev)
 543 {
 544         conf_t *conf = mddev_to_conf(mddev);
 545         int i;
 546
 547         rcu_read_lock();
 548         for (i=0; i<mddev->raid_disks; i++) {
 549                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 550                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
 551                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
 552
 553                         atomic_inc(&rdev->nr_pending);
 554                         rcu_read_unlock();
 555
 556                         if (r_queue->unplug_fn)
 557                                 r_queue->unplug_fn(r_queue);
 558
 559                         rdev_dec_pending(rdev, mddev);
 560                         rcu_read_lock();
 561                 }
 562         }
 563         rcu_read_unlock();
 564 }
 565
 566 static void raid1_unplug(request_queue_t *q)
 567 {
 568         mddev_t *mddev = q->queuedata;
 569
 570         unplug_slaves(mddev);
 571         md_wakeup_thread(mddev->thread);
 572 }
 573
 574 static int raid1_issue_flush(request_queue_t *q, struct gendisk *disk,
 575                              sector_t *error_sector)
 576 {
 577         mddev_t *mddev = q->queuedata;
 578         conf_t *conf = mddev_to_conf(mddev);
 579         int i, ret = 0;
 580
 581         rcu_read_lock();
 582         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
 583                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 584                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 585                         struct block_device *bdev = rdev->bdev;
 586                         request_queue_t *r_queue = bdev_get_queue(bdev);
 587
 588                         if (!r_queue->issue_flush_fn)
 589                                 ret = -EOPNOTSUPP;
 590                         else {
 591                                 atomic_inc(&rdev->nr_pending);
 592                                 rcu_read_unlock();
 593                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
 594                                                               error_sector);
 595                                 rdev_dec_pending(rdev, mddev);
 596                                 rcu_read_lock();
 597                         }
 598                 }
 599         }
 600         rcu_read_unlock();
 601         return ret;
 602 }
 603
 604 /* Barriers....
 605  * Sometimes we need to suspend IO while we do something else,
 606  * either some resync/recovery, or reconfigure the array.
 607  * To do this we raise a 'barrier'.
 608  * The 'barrier' is a counter that can be raised multiple times
 609  * to count how many activities are happening which preclude
 610  * normal IO.
 611  * We can only raise the barrier if there is no pending IO.
 612  * i.e. if nr_pending == 0.
 613  * We choose only to raise the barrier if no-one is waiting for the
 614  * barrier to go down.  This means that as soon as an IO request
 615  * is ready, no other operations which require a barrier will start
 616  * until the IO request has had a chance.
 617  *
 618  * So: regular IO calls 'wait_barrier'.  When that returns there
 619  *    is no backgroup IO happening,  It must arrange to call
 620  *    allow_barrier when it has finished its IO.
 621  * backgroup IO calls must call raise_barrier.  Once that returns
 622  *    there is no normal IO happeing.  It must arrange to call
 623  *    lower_barrier when the particular background IO completes.
 624  */
 625 #define RESYNC_DEPTH 32
 626
 627 static void raise_barrier(conf_t *conf)
 628 {
 629         spin_lock_irq(&conf->resync_lock);
 630
 631         /* Wait until no block IO is waiting */
 632         wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
 633                             conf->resync_lock,
 634                             raid1_unplug(conf->mddev->queue));
 635
 636         /* block any new IO from starting */
 637         conf->barrier++;
 638
 639         /* No wait for all pending IO to complete */
 640         wait_event_lock_irq(conf->wait_barrier,
 641                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 642                             conf->resync_lock,
 643                             raid1_unplug(conf->mddev->queue));
 644
 645         spin_unlock_irq(&conf->resync_lock);
 646 }
 647
 648 static void lower_barrier(conf_t *conf)
 649 {
 650         unsigned long flags;
 651         spin_lock_irqsave(&conf->resync_lock, flags);
 652         conf->barrier--;
 653         spin_unlock_irqrestore(&conf->resync_lock, flags);
 654         wake_up(&conf->wait_barrier);
 655 }
 656
 657 static void wait_barrier(conf_t *conf)
 658 {
 659         spin_lock_irq(&conf->resync_lock);
 660         if (conf->barrier) {
 661                 conf->nr_waiting++;
 662                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
 663                                     conf->resync_lock,
 664                                     raid1_unplug(conf->mddev->queue));
 665                 conf->nr_waiting--;
 666         }
 667         conf->nr_pending++;
 668         spin_unlock_irq(&conf->resync_lock);
 669 }
 670
 671 static void allow_barrier(conf_t *conf)
 672 {
 673         unsigned long flags;
 674         spin_lock_irqsave(&conf->resync_lock, flags);
 675         conf->nr_pending--;
 676         spin_unlock_irqrestore(&conf->resync_lock, flags);
 677         wake_up(&conf->wait_barrier);
 678 }
 679
 680 static void freeze_array(conf_t *conf)
 681 {
 682         /* stop syncio and normal IO and wait for everything to
 683          * go quite.
 684          * We increment barrier and nr_waiting, and then
 685          * wait until barrier+nr_pending match nr_queued+2
 686          */
 687         spin_lock_irq(&conf->resync_lock);
 688         conf->barrier++;
 689         conf->nr_waiting++;
 690         wait_event_lock_irq(conf->wait_barrier,
 691                             conf->barrier+conf->nr_pending == conf->nr_queued+2,
 692                             conf->resync_lock,
 693                             raid1_unplug(conf->mddev->queue));
 694         spin_unlock_irq(&conf->resync_lock);
 695 }
 696 static void unfreeze_array(conf_t *conf)
 697 {
 698         /* reverse the effect of the freeze */
 699         spin_lock_irq(&conf->resync_lock);
 700         conf->barrier--;
 701         conf->nr_waiting--;
 702         wake_up(&conf->wait_barrier);
 703         spin_unlock_irq(&conf->resync_lock);
 704 }
 705
 706
 707 /* duplicate the data pages for behind I/O */
 708 static struct page **alloc_behind_pages(struct bio *bio)
 709 {
 710         int i;
 711         struct bio_vec *bvec;
 712         struct page **pages = kzalloc(bio->bi_vcnt * sizeof(struct page *),
 713                                         GFP_NOIO);
 714         if (unlikely(!pages))
 715                 goto do_sync_io;
 716
 717         bio_for_each_segment(bvec, bio, i) {
 718                 pages[i] = alloc_page(GFP_NOIO);
 719                 if (unlikely(!pages[i]))
 720                         goto do_sync_io;
 721                 memcpy(kmap(pages[i]) + bvec->bv_offset,
 722                         kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
 723                 kunmap(pages[i]);
 724                 kunmap(bvec->bv_page);
 725         }
 726
 727         return pages;
 728
 729 do_sync_io:
 730         if (pages)
 731                 for (i = 0; i < bio->bi_vcnt && pages[i]; i++)
 732                         put_page(pages[i]);
 733         kfree(pages);
 734         PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
 735         return NULL;
 736 }
 737
 738 static int make_request(request_queue_t *q, struct bio * bio)
 739 {
 740         mddev_t *mddev = q->queuedata;
 741         conf_t *conf = mddev_to_conf(mddev);
 742         mirror_info_t *mirror;
 743         r1bio_t *r1_bio;
 744         struct bio *read_bio;
 745         int i, targets = 0, disks;
 746         mdk_rdev_t *rdev;
 747         struct bitmap *bitmap = mddev->bitmap;
 748         unsigned long flags;
 749         struct bio_list bl;
 750         struct page **behind_pages = NULL;
 751         const int rw = bio_data_dir(bio);
 752         int do_barriers;
 753
 754         /*
 755          * Register the new request and wait if the reconstruction
 756          * thread has put up a bar for new requests.
 757          * Continue immediately if no resync is active currently.
 758          * We test barriers_work *after* md_write_start as md_write_start
 759          * may cause the first superblock write, and that will check out
 760          * if barriers work.
 761          */
 762
 763         md_write_start(mddev, bio); /* wait on superblock update early */
 764
 765         if (unlikely(!mddev->barriers_work && bio_barrier(bio))) {
 766                 if (rw == WRITE)
 767                         md_write_end(mddev);
 768                 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
 769                 return 0;
 770         }
 771
 772         wait_barrier(conf);
 773
 774         disk_stat_inc(mddev->gendisk, ios[rw]);
 775         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
 776
 777         /*
 778          * make_request() can abort the operation when READA is being
 779          * used and no empty request is available.
 780          *
 781          */
 782         r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
 783
 784         r1_bio->master_bio = bio;
 785         r1_bio->sectors = bio->bi_size >> 9;
 786         r1_bio->state = 0;
 787         r1_bio->mddev = mddev;
 788         r1_bio->sector = bio->bi_sector;
 789
 790         if (rw == READ) {
 791                 /*
 792                  * read balancing logic:
 793                  */
 794                 int rdisk = read_balance(conf, r1_bio);
 795
 796                 if (rdisk < 0) {
 797                         /* couldn't find anywhere to read from */
 798                         raid_end_bio_io(r1_bio);
 799                         return 0;
 800                 }
 801                 mirror = conf->mirrors + rdisk;
 802
 803                 r1_bio->read_disk = rdisk;
 804
 805                 read_bio = bio_clone(bio, GFP_NOIO);
 806
 807                 r1_bio->bios[rdisk] = read_bio;
 808
 809                 read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
 810                 read_bio->bi_bdev = mirror->rdev->bdev;
 811                 read_bio->bi_end_io = raid1_end_read_request;
 812                 read_bio->bi_rw = READ;
 813                 read_bio->bi_private = r1_bio;
 814
 815                 generic_make_request(read_bio);
 816                 return 0;
 817         }
 818
 819         /*
 820          * WRITE:
 821          */
 822         /* first select target devices under spinlock and
 823          * inc refcount on their rdev.  Record them by setting
 824          * bios[x] to bio
 825          */
 826         disks = conf->raid_disks;
 827 #if 0
 828         { static int first=1;
 829         if (first) printk("First Write sector %llu disks %d\n",
 830                           (unsigned long long)r1_bio->sector, disks);
 831         first = 0;
 832         }
 833 #endif
 834         rcu_read_lock();
 835         for (i = 0;  i < disks; i++) {
 836                 if ((rdev=rcu_dereference(conf->mirrors[i].rdev)) != NULL &&
 837                     !test_bit(Faulty, &rdev->flags)) {
 838                         atomic_inc(&rdev->nr_pending);
 839                         if (test_bit(Faulty, &rdev->flags)) {
 840                                 rdev_dec_pending(rdev, mddev);
 841                                 r1_bio->bios[i] = NULL;
 842                         } else
 843                                 r1_bio->bios[i] = bio;
 844                         targets++;
 845                 } else
 846                         r1_bio->bios[i] = NULL;
 847         }
 848         rcu_read_unlock();
 849
 850         BUG_ON(targets == 0); /* we never fail the last device */
 851
 852         if (targets < conf->raid_disks) {
 853                 /* array is degraded, we will not clear the bitmap
 854                  * on I/O completion (see raid1_end_write_request) */
 855                 set_bit(R1BIO_Degraded, &r1_bio->state);
 856         }
 857
 858         /* do behind I/O ? */
 859         if (bitmap &&
 860             atomic_read(&bitmap->behind_writes) < bitmap->max_write_behind &&
 861             (behind_pages = alloc_behind_pages(bio)) != NULL)
 862                 set_bit(R1BIO_BehindIO, &r1_bio->state);
 863
 864         atomic_set(&r1_bio->remaining, 0);
 865         atomic_set(&r1_bio->behind_remaining, 0);
 866
 867         do_barriers = bio_barrier(bio);
 868         if (do_barriers)
 869                 set_bit(R1BIO_Barrier, &r1_bio->state);
 870
 871         bio_list_init(&bl);
 872         for (i = 0; i < disks; i++) {
 873                 struct bio *mbio;
 874                 if (!r1_bio->bios[i])
 875                         continue;
 876
 877                 mbio = bio_clone(bio, GFP_NOIO);
 878                 r1_bio->bios[i] = mbio;
 879
 880                 mbio->bi_sector = r1_bio->sector + conf->mirrors[i].rdev->data_offset;
 881                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
 882                 mbio->bi_end_io = raid1_end_write_request;
 883                 mbio->bi_rw = WRITE | do_barriers;
 884                 mbio->bi_private = r1_bio;
 885
 886                 if (behind_pages) {
 887                         struct bio_vec *bvec;
 888                         int j;
 889
 890                         /* Yes, I really want the '__' version so that
 891                          * we clear any unused pointer in the io_vec, rather
 892                          * than leave them unchanged.  This is important
 893                          * because when we come to free the pages, we won't
 894                          * know the originial bi_idx, so we just free
 895                          * them all
 896                          */
 897                         __bio_for_each_segment(bvec, mbio, j, 0)
 898                                 bvec->bv_page = behind_pages[j];
 899                         if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
 900                                 atomic_inc(&r1_bio->behind_remaining);
 901                 }
 902
 903                 atomic_inc(&r1_bio->remaining);
 904
 905                 bio_list_add(&bl, mbio);
 906         }
 907         kfree(behind_pages); /* the behind pages are attached to the bios now */
 908
 909         bitmap_startwrite(bitmap, bio->bi_sector, r1_bio->sectors,
 910                                 test_bit(R1BIO_BehindIO, &r1_bio->state));
 911         spin_lock_irqsave(&conf->device_lock, flags);
 912         bio_list_merge(&conf->pending_bio_list, &bl);
 913         bio_list_init(&bl);
 914
 915         blk_plug_device(mddev->queue);
 916         spin_unlock_irqrestore(&conf->device_lock, flags);
 917
 918 #if 0
 919         while ((bio = bio_list_pop(&bl)) != NULL)
 920                 generic_make_request(bio);
 921 #endif
 922
 923         return 0;
 924 }
 925
 926 static void status(struct seq_file *seq, mddev_t *mddev)
 927 {
 928         conf_t *conf = mddev_to_conf(mddev);
 929         int i;
 930
 931         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 932                                                 conf->working_disks);
 933         for (i = 0; i < conf->raid_disks; i++)
 934                 seq_printf(seq, "%s",
 935                               conf->mirrors[i].rdev &&
 936                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
 937         seq_printf(seq, "]");
 938 }
 939
 940
 941 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 942 {
 943         char b[BDEVNAME_SIZE];
 944         conf_t *conf = mddev_to_conf(mddev);
 945
 946         /*
 947          * If it is not operational, then we have already marked it as dead
 948          * else if it is the last working disks, ignore the error, let the
 949          * next level up know.
 950          * else mark the drive as failed
 951          */
 952         if (test_bit(In_sync, &rdev->flags)
 953             && conf->working_disks == 1)
 954                 /*
 955                  * Don't fail the drive, act as though we were just a
 956                  * normal single drive
 957                  */
 958                 return;
 959         if (test_bit(In_sync, &rdev->flags)) {
 960                 mddev->degraded++;
 961                 conf->working_disks--;
 962                 /*
 963                  * if recovery is running, make sure it aborts.
 964                  */
 965                 set_bit(MD_RECOVERY_ERR, &mddev->recovery);
 966         }
 967         clear_bit(In_sync, &rdev->flags);
 968         set_bit(Faulty, &rdev->flags);
 969         mddev->sb_dirty = 1;
 970         printk(KERN_ALERT "raid1: Disk failure on %s, disabling device. \n"
 971                 "       Operation continuing on %d devices\n",
 972                 bdevname(rdev->bdev,b), conf->working_disks);
 973 }
 974
 975 static void print_conf(conf_t *conf)
 976 {
 977         int i;
 978         mirror_info_t *tmp;
 979
 980         printk("RAID1 conf printout:\n");
 981         if (!conf) {
 982                 printk("(!conf)\n");
 983                 return;
 984         }
 985         printk(" --- wd:%d rd:%d\n", conf->working_disks,
 986                 conf->raid_disks);
 987
 988         for (i = 0; i < conf->raid_disks; i++) {
 989                 char b[BDEVNAME_SIZE];
 990                 tmp = conf->mirrors + i;
 991                 if (tmp->rdev)
 992                         printk(" disk %d, wo:%d, o:%d, dev:%s\n",
 993                                 i, !test_bit(In_sync, &tmp->rdev->flags), !test_bit(Faulty, &tmp->rdev->flags),
 994                                 bdevname(tmp->rdev->bdev,b));
 995         }
 996 }
 997
 998 static void close_sync(conf_t *conf)
 999 {
1000         wait_barrier(conf);
1001         allow_barrier(conf);
1002
1003         mempool_destroy(conf->r1buf_pool);
1004         conf->r1buf_pool = NULL;
1005 }
1006
1007 static int raid1_spare_active(mddev_t *mddev)
1008 {
1009         int i;
1010         conf_t *conf = mddev->private;
1011         mirror_info_t *tmp;
1012
1013         /*
1014          * Find all failed disks within the RAID1 configuration
1015          * and mark them readable
1016          */
1017         for (i = 0; i < conf->raid_disks; i++) {
1018                 tmp = conf->mirrors + i;
1019                 if (tmp->rdev
1020                     && !test_bit(Faulty, &tmp->rdev->flags)
1021                     && !test_bit(In_sync, &tmp->rdev->flags)) {
1022                         conf->working_disks++;
1023                         mddev->degraded--;
1024                         set_bit(In_sync, &tmp->rdev->flags);
1025                 }
1026         }
1027
1028         print_conf(conf);
1029         return 0;
1030 }
1031
1032
1033 static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1034 {
1035         conf_t *conf = mddev->private;
1036         int found = 0;
1037         int mirror = 0;
1038         mirror_info_t *p;
1039
1040         for (mirror=0; mirror < mddev->raid_disks; mirror++)
1041                 if ( !(p=conf->mirrors+mirror)->rdev) {
1042
1043                         blk_queue_stack_limits(mddev->queue,
1044                                                rdev->bdev->bd_disk->queue);
1045                         /* as we don't honour merge_bvec_fn, we must never risk
1046                          * violating it, so limit ->max_sector to one PAGE, as
1047                          * a one page request is never in violation.
1048                          */
1049                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1050                             mddev->queue->max_sectors > (PAGE_SIZE>>9))
1051                                 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
1052
1053                         p->head_position = 0;
1054                         rdev->raid_disk = mirror;
1055                         found = 1;
1056                         /* As all devices are equivalent, we don't need a full recovery
1057                          * if this was recently any drive of the array
1058                          */
1059                         if (rdev->saved_raid_disk < 0)
1060                                 conf->fullsync = 1;
1061                         rcu_assign_pointer(p->rdev, rdev);
1062                         break;
1063                 }
1064
1065         print_conf(conf);
1066         return found;
1067 }
1068
1069 static int raid1_remove_disk(mddev_t *mddev, int number)
1070 {
1071         conf_t *conf = mddev->private;
1072         int err = 0;
1073         mdk_rdev_t *rdev;
1074         mirror_info_t *p = conf->mirrors+ number;
1075
1076         print_conf(conf);
1077         rdev = p->rdev;
1078         if (rdev) {
1079                 if (test_bit(In_sync, &rdev->flags) ||
1080                     atomic_read(&rdev->nr_pending)) {
1081                         err = -EBUSY;
1082                         goto abort;
1083                 }
1084                 p->rdev = NULL;
1085                 synchronize_rcu();
1086                 if (atomic_read(&rdev->nr_pending)) {
1087                         /* lost the race, try later */
1088                         err = -EBUSY;
1089                         p->rdev = rdev;
1090                 }
1091         }
1092 abort:
1093
1094         print_conf(conf);
1095         return err;
1096 }
1097
1098
1099 static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error)
1100 {
1101         r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
1102         int i;
1103
1104         if (bio->bi_size)
1105                 return 1;
1106
1107         for (i=r1_bio->mddev->raid_disks; i--; )
1108                 if (r1_bio->bios[i] == bio)
1109                         break;
1110         BUG_ON(i < 0);
1111         update_head_pos(i, r1_bio);
1112         /*
1113          * we have read a block, now it needs to be re-written,
1114          * or re-read if the read failed.
1115          * We don't do much here, just schedule handling by raid1d
1116          */
1117         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1118                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1119
1120         if (atomic_dec_and_test(&r1_bio->remaining))
1121                 reschedule_retry(r1_bio);
1122         return 0;
1123 }
1124
1125 static int end_sync_write(struct bio *bio, unsigned int bytes_done, int error)
1126 {
1127         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1128         r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
1129         mddev_t *mddev = r1_bio->mddev;
1130         conf_t *conf = mddev_to_conf(mddev);
1131         int i;
1132         int mirror=0;
1133
1134         if (bio->bi_size)
1135                 return 1;
1136
1137         for (i = 0; i < conf->raid_disks; i++)
1138                 if (r1_bio->bios[i] == bio) {
1139                         mirror = i;
1140                         break;
1141                 }
1142         if (!uptodate) {
1143                 int sync_blocks = 0;
1144                 sector_t s = r1_bio->sector;
1145                 long sectors_to_go = r1_bio->sectors;
1146                 /* make sure these bits doesn't get cleared. */
1147                 do {
1148                         bitmap_end_sync(mddev->bitmap, r1_bio->sector,
1149                                         &sync_blocks, 1);
1150                         s += sync_blocks;
1151                         sectors_to_go -= sync_blocks;
1152                 } while (sectors_to_go > 0);
1153                 md_error(mddev, conf->mirrors[mirror].rdev);
1154         }
1155
1156         update_head_pos(mirror, r1_bio);
1157
1158         if (atomic_dec_and_test(&r1_bio->remaining)) {
1159                 md_done_sync(mddev, r1_bio->sectors, uptodate);
1160                 put_buf(r1_bio);
1161         }
1162         return 0;
1163 }
1164
1165 static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
1166 {
1167         conf_t *conf = mddev_to_conf(mddev);
1168         int i;
1169         int disks = conf->raid_disks;
1170         struct bio *bio, *wbio;
1171
1172         bio = r1_bio->bios[r1_bio->read_disk];
1173
1174
1175         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1176                 /* We have read all readable devices.  If we haven't
1177                  * got the block, then there is no hope left.
1178                  * If we have, then we want to do a comparison
1179                  * and skip the write if everything is the same.
1180                  * If any blocks failed to read, then we need to
1181                  * attempt an over-write
1182                  */
1183                 int primary;
1184                 if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
1185                         for (i=0; i<mddev->raid_disks; i++)
1186                                 if (r1_bio->bios[i]->bi_end_io == end_sync_read)
1187                                         md_error(mddev, conf->mirrors[i].rdev);
1188
1189                         md_done_sync(mddev, r1_bio->sectors, 1);
1190                         put_buf(r1_bio);
1191                         return;
1192                 }
1193                 for (primary=0; primary<mddev->raid_disks; primary++)
1194                         if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
1195                             test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
1196                                 r1_bio->bios[primary]->bi_end_io = NULL;
1197                                 rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
1198                                 break;
1199                         }
1200                 r1_bio->read_disk = primary;
1201                 for (i=0; i<mddev->raid_disks; i++)
1202                         if (r1_bio->bios[i]->bi_end_io == end_sync_read &&
1203                             test_bit(BIO_UPTODATE, &r1_bio->bios[i]->bi_flags)) {
1204                                 int j;
1205                                 int vcnt = r1_bio->sectors >> (PAGE_SHIFT- 9);
1206                                 struct bio *pbio = r1_bio->bios[primary];
1207                                 struct bio *sbio = r1_bio->bios[i];
1208                                 for (j = vcnt; j-- ; )
1209                                         if (memcmp(page_address(pbio->bi_io_vec[j].bv_page),
1210                                                    page_address(sbio->bi_io_vec[j].bv_page),
1211                                                    PAGE_SIZE))
1212                                                 break;
1213                                 if (j >= 0)
1214                                         mddev->resync_mismatches += r1_bio->sectors;
1215                                 if (j < 0 || test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
1216                                         sbio->bi_end_io = NULL;
1217                                         rdev_dec_pending(conf->mirrors[i].rdev, mddev);
1218                                 } else {
1219                                         /* fixup the bio for reuse */
1220                                         sbio->bi_vcnt = vcnt;
1221                                         sbio->bi_size = r1_bio->sectors << 9;
1222                                         sbio->bi_idx = 0;
1223                                         sbio->bi_phys_segments = 0;
1224                                         sbio->bi_hw_segments = 0;
1225                                         sbio->bi_hw_front_size = 0;
1226                                         sbio->bi_hw_back_size = 0;
1227                                         sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1228                                         sbio->bi_flags |= 1 << BIO_UPTODATE;
1229                                         sbio->bi_next = NULL;
1230                                         sbio->bi_sector = r1_bio->sector +
1231                                                 conf->mirrors[i].rdev->data_offset;
1232                                         sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
1233                                 }
1234                         }
1235         }
1236         if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
1237                 /* ouch - failed to read all of that.
1238                  * Try some synchronous reads of other devices to get
1239                  * good data, much like with normal read errors.  Only
1240                  * read into the pages we already have so they we don't
1241                  * need to re-issue the read request.
1242                  * We don't need to freeze the array, because being in an
1243                  * active sync request, there is no normal IO, and
1244                  * no overlapping syncs.
1245                  */
1246                 sector_t sect = r1_bio->sector;
1247                 int sectors = r1_bio->sectors;
1248                 int idx = 0;
1249
1250                 while(sectors) {
1251                         int s = sectors;
1252                         int d = r1_bio->read_disk;
1253                         int success = 0;
1254                         mdk_rdev_t *rdev;
1255
1256                         if (s > (PAGE_SIZE>>9))
1257                                 s = PAGE_SIZE >> 9;
1258                         do {
1259                                 if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
1260                                         rdev = conf->mirrors[d].rdev;
1261                                         if (sync_page_io(rdev->bdev,
1262                                                          sect + rdev->data_offset,
1263                                                          s<<9,
1264                                                          bio->bi_io_vec[idx].bv_page,
1265                                                          READ)) {
1266                                                 success = 1;
1267                                                 break;
1268                                         }
1269                                 }
1270                                 d++;
1271                                 if (d == conf->raid_disks)
1272                                         d = 0;
1273                         } while (!success && d != r1_bio->read_disk);
1274
1275                         if (success) {
1276                                 int start = d;
1277                                 /* write it back and re-read */
1278                                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1279                                 while (d != r1_bio->read_disk) {
1280                                         if (d == 0)
1281                                                 d = conf->raid_disks;
1282                                         d--;
1283                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1284                                                 continue;
1285                                         rdev = conf->mirrors[d].rdev;
1286                                         atomic_add(s, &rdev->corrected_errors);
1287                                         if (sync_page_io(rdev->bdev,
1288                                                          sect + rdev->data_offset,
1289                                                          s<<9,
1290                                                          bio->bi_io_vec[idx].bv_page,
1291                                                          WRITE) == 0)
1292                                                 md_error(mddev, rdev);
1293                                 }
1294                                 d = start;
1295                                 while (d != r1_bio->read_disk) {
1296                                         if (d == 0)
1297                                                 d = conf->raid_disks;
1298                                         d--;
1299                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1300                                                 continue;
1301                                         rdev = conf->mirrors[d].rdev;
1302                                         if (sync_page_io(rdev->bdev,
1303                                                          sect + rdev->data_offset,
1304                                                          s<<9,
1305                                                          bio->bi_io_vec[idx].bv_page,
1306                                                          READ) == 0)
1307                                                 md_error(mddev, rdev);
1308                                 }
1309                         } else {
1310                                 char b[BDEVNAME_SIZE];
1311                                 /* Cannot read from anywhere, array is toast */
1312                                 md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
1313                                 printk(KERN_ALERT "raid1: %s: unrecoverable I/O read error"
1314                                        " for block %llu\n",
1315                                        bdevname(bio->bi_bdev,b),
1316                                        (unsigned long long)r1_bio->sector);
1317                                 md_done_sync(mddev, r1_bio->sectors, 0);
1318                                 put_buf(r1_bio);
1319                                 return;
1320                         }
1321                         sectors -= s;
1322                         sect += s;
1323                         idx ++;
1324                 }
1325         }
1326
1327         /*
1328          * schedule writes
1329          */
1330         atomic_set(&r1_bio->remaining, 1);
1331         for (i = 0; i < disks ; i++) {
1332                 wbio = r1_bio->bios[i];
1333                 if (wbio->bi_end_io == NULL ||
1334                     (wbio->bi_end_io == end_sync_read &&
1335                      (i == r1_bio->read_disk ||
1336                       !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
1337                         continue;
1338
1339                 wbio->bi_rw = WRITE;
1340                 wbio->bi_end_io = end_sync_write;
1341                 atomic_inc(&r1_bio->remaining);
1342                 md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
1343
1344                 generic_make_request(wbio);
1345         }
1346
1347         if (atomic_dec_and_test(&r1_bio->remaining)) {
1348                 /* if we're here, all write(s) have completed, so clean up */
1349                 md_done_sync(mddev, r1_bio->sectors, 1);
1350                 put_buf(r1_bio);
1351         }
1352 }
1353
1354 /*
1355  * This is a kernel thread which:
1356  *
1357  *      1.      Retries failed read operations on working mirrors.
1358  *      2.      Updates the raid superblock when problems encounter.
1359  *      3.      Performs writes following reads for array syncronising.
1360  */
1361
1362 static void raid1d(mddev_t *mddev)
1363 {
1364         r1bio_t *r1_bio;
1365         struct bio *bio;
1366         unsigned long flags;
1367         conf_t *conf = mddev_to_conf(mddev);
1368         struct list_head *head = &conf->retry_list;
1369         int unplug=0;
1370         mdk_rdev_t *rdev;
1371
1372         md_check_recovery(mddev);
1373
1374         for (;;) {
1375                 char b[BDEVNAME_SIZE];
1376                 spin_lock_irqsave(&conf->device_lock, flags);
1377
1378                 if (conf->pending_bio_list.head) {
1379                         bio = bio_list_get(&conf->pending_bio_list);
1380                         blk_remove_plug(mddev->queue);
1381                         spin_unlock_irqrestore(&conf->device_lock, flags);
1382                         /* flush any pending bitmap writes to disk before proceeding w/ I/O */
1383                         if (bitmap_unplug(mddev->bitmap) != 0)
1384                                 printk("%s: bitmap file write failed!\n", mdname(mddev));
1385
1386                         while (bio) { /* submit pending writes */
1387                                 struct bio *next = bio->bi_next;
1388                                 bio->bi_next = NULL;
1389                                 generic_make_request(bio);
1390                                 bio = next;
1391                         }
1392                         unplug = 1;
1393
1394                         continue;
1395                 }
1396
1397                 if (list_empty(head))
1398                         break;
1399                 r1_bio = list_entry(head->prev, r1bio_t, retry_list);
1400                 list_del(head->prev);
1401                 conf->nr_queued--;
1402                 spin_unlock_irqrestore(&conf->device_lock, flags);
1403
1404                 mddev = r1_bio->mddev;
1405                 conf = mddev_to_conf(mddev);
1406                 if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
1407                         sync_request_write(mddev, r1_bio);
1408                         unplug = 1;
1409                 } else if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
1410                         /* some requests in the r1bio were BIO_RW_BARRIER
1411                          * requests which failed with -EOPNOTSUPP.  Hohumm..
1412                          * Better resubmit without the barrier.
1413                          * We know which devices to resubmit for, because
1414                          * all others have had their bios[] entry cleared.
1415                          * We already have a nr_pending reference on these rdevs.
1416                          */
1417                         int i;
1418                         clear_bit(R1BIO_BarrierRetry, &r1_bio->state);
1419                         clear_bit(R1BIO_Barrier, &r1_bio->state);
1420                         for (i=0; i < conf->raid_disks; i++)
1421                                 if (r1_bio->bios[i])
1422                                         atomic_inc(&r1_bio->remaining);
1423                         for (i=0; i < conf->raid_disks; i++)
1424                                 if (r1_bio->bios[i]) {
1425                                         struct bio_vec *bvec;
1426                                         int j;
1427
1428                                         bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
1429                                         /* copy pages from the failed bio, as
1430                                          * this might be a write-behind device */
1431                                         __bio_for_each_segment(bvec, bio, j, 0)
1432                                                 bvec->bv_page = bio_iovec_idx(r1_bio->bios[i], j)->bv_page;
1433                                         bio_put(r1_bio->bios[i]);
1434                                         bio->bi_sector = r1_bio->sector +
1435                                                 conf->mirrors[i].rdev->data_offset;
1436                                         bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1437                                         bio->bi_end_io = raid1_end_write_request;
1438                                         bio->bi_rw = WRITE;
1439                                         bio->bi_private = r1_bio;
1440                                         r1_bio->bios[i] = bio;
1441                                         generic_make_request(bio);
1442                                 }
1443                 } else {
1444                         int disk;
1445
1446                         /* we got a read error. Maybe the drive is bad.  Maybe just
1447                          * the block and we can fix it.
1448                          * We freeze all other IO, and try reading the block from
1449                          * other devices.  When we find one, we re-write
1450                          * and check it that fixes the read error.
1451                          * This is all done synchronously while the array is
1452                          * frozen
1453                          */
1454                         sector_t sect = r1_bio->sector;
1455                         int sectors = r1_bio->sectors;
1456                         freeze_array(conf);
1457                         if (mddev->ro == 0) while(sectors) {
1458                                 int s = sectors;
1459                                 int d = r1_bio->read_disk;
1460                                 int success = 0;
1461
1462                                 if (s > (PAGE_SIZE>>9))
1463                                         s = PAGE_SIZE >> 9;
1464
1465                                 do {
1466                                         rdev = conf->mirrors[d].rdev;
1467                                         if (rdev &&
1468                                             test_bit(In_sync, &rdev->flags) &&
1469                                             sync_page_io(rdev->bdev,
1470                                                          sect + rdev->data_offset,
1471                                                          s<<9,
1472                                                          conf->tmppage, READ))
1473                                                 success = 1;
1474                                         else {
1475                                                 d++;
1476                                                 if (d == conf->raid_disks)
1477                                                         d = 0;
1478                                         }
1479                                 } while (!success && d != r1_bio->read_disk);
1480
1481                                 if (success) {
1482                                         /* write it back and re-read */
1483                                         int start = d;
1484                                         while (d != r1_bio->read_disk) {
1485                                                 if (d==0)
1486                                                         d = conf->raid_disks;
1487                                                 d--;
1488                                                 rdev = conf->mirrors[d].rdev;
1489                                                 atomic_add(s, &rdev->corrected_errors);
1490                                                 if (rdev &&
1491                                                     test_bit(In_sync, &rdev->flags)) {
1492                                                         if (sync_page_io(rdev->bdev,
1493                                                                          sect + rdev->data_offset,
1494                                                                          s<<9, conf->tmppage, WRITE) == 0)
1495                                                                 /* Well, this device is dead */
1496                                                                 md_error(mddev, rdev);
1497                                                 }
1498                                         }
1499                                         d = start;
1500                                         while (d != r1_bio->read_disk) {
1501                                                 if (d==0)
1502                                                         d = conf->raid_disks;
1503                                                 d--;
1504                                                 rdev = conf->mirrors[d].rdev;
1505                                                 if (rdev &&
1506                                                     test_bit(In_sync, &rdev->flags)) {
1507                                                         if (sync_page_io(rdev->bdev,
1508                                                                          sect + rdev->data_offset,
1509                                                                          s<<9, conf->tmppage, READ) == 0)
1510                                                                 /* Well, this device is dead */
1511                                                                 md_error(mddev, rdev);
1512                                                 }
1513                                         }
1514                                 } else {
1515                                         /* Cannot read from anywhere -- bye bye array */
1516                                         md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
1517                                         break;
1518                                 }
1519                                 sectors -= s;
1520                                 sect += s;
1521                         }
1522
1523                         unfreeze_array(conf);
1524
1525                         bio = r1_bio->bios[r1_bio->read_disk];
1526                         if ((disk=read_balance(conf, r1_bio)) == -1) {
1527                                 printk(KERN_ALERT "raid1: %s: unrecoverable I/O"
1528                                        " read error for block %llu\n",
1529                                        bdevname(bio->bi_bdev,b),
1530                                        (unsigned long long)r1_bio->sector);
1531                                 raid_end_bio_io(r1_bio);
1532                         } else {
1533                                 r1_bio->bios[r1_bio->read_disk] =
1534                                         mddev->ro ? IO_BLOCKED : NULL;
1535                                 r1_bio->read_disk = disk;
1536                                 bio_put(bio);
1537                                 bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
1538                                 r1_bio->bios[r1_bio->read_disk] = bio;
1539                                 rdev = conf->mirrors[disk].rdev;
1540                                 if (printk_ratelimit())
1541                                         printk(KERN_ERR "raid1: %s: redirecting sector %llu to"
1542                                                " another mirror\n",
1543                                                bdevname(rdev->bdev,b),
1544                                                (unsigned long long)r1_bio->sector);
1545                                 bio->bi_sector = r1_bio->sector + rdev->data_offset;
1546                                 bio->bi_bdev = rdev->bdev;
1547                                 bio->bi_end_io = raid1_end_read_request;
1548                                 bio->bi_rw = READ;
1549                                 bio->bi_private = r1_bio;
1550                                 unplug = 1;
1551                                 generic_make_request(bio);
1552                         }
1553                 }
1554         }
1555         spin_unlock_irqrestore(&conf->device_lock, flags);
1556         if (unplug)
1557                 unplug_slaves(mddev);
1558 }
1559
1560
1561 static int init_resync(conf_t *conf)
1562 {
1563         int buffs;
1564
1565         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1566         BUG_ON(conf->r1buf_pool);
1567         conf->r1buf_pool = mempool_create(buffs, r1buf_pool_alloc, r1buf_pool_free,
1568                                           conf->poolinfo);
1569         if (!conf->r1buf_pool)
1570                 return -ENOMEM;
1571         conf->next_resync = 0;
1572         return 0;
1573 }
1574
1575 /*
1576  * perform a "sync" on one "block"
1577  *
1578  * We need to make sure that no normal I/O request - particularly write
1579  * requests - conflict with active sync requests.
1580  *
1581  * This is achieved by tracking pending requests and a 'barrier' concept
1582  * that can be installed to exclude normal IO requests.
1583  */
1584
1585 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1586 {
1587         conf_t *conf = mddev_to_conf(mddev);
1588         r1bio_t *r1_bio;
1589         struct bio *bio;
1590         sector_t max_sector, nr_sectors;
1591         int disk = -1;
1592         int i;
1593         int wonly = -1;
1594         int write_targets = 0, read_targets = 0;
1595         int sync_blocks;
1596         int still_degraded = 0;
1597
1598         if (!conf->r1buf_pool)
1599         {
1600 /*
1601                 printk("sync start - bitmap %p\n", mddev->bitmap);
1602 */
1603                 if (init_resync(conf))
1604                         return 0;
1605         }
1606
1607         max_sector = mddev->size << 1;
1608         if (sector_nr >= max_sector) {
1609                 /* If we aborted, we need to abort the
1610                  * sync on the 'current' bitmap chunk (there will
1611                  * only be one in raid1 resync.
1612                  * We can find the current addess in mddev->curr_resync
1613                  */
1614                 if (mddev->curr_resync < max_sector) /* aborted */
1615                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1616                                                 &sync_blocks, 1);
1617                 else /* completed sync */
1618                         conf->fullsync = 0;
1619
1620                 bitmap_close_sync(mddev->bitmap);
1621                 close_sync(conf);
1622                 return 0;
1623         }
1624
1625         /* before building a request, check if we can skip these blocks..
1626          * This call the bitmap_start_sync doesn't actually record anything
1627          */
1628         if (mddev->bitmap == NULL &&
1629             mddev->recovery_cp == MaxSector &&
1630             conf->fullsync == 0) {
1631                 *skipped = 1;
1632                 return max_sector - sector_nr;
1633         }
1634         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1635             !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1636                 /* We can skip this block, and probably several more */
1637                 *skipped = 1;
1638                 return sync_blocks;
1639         }
1640         /*
1641          * If there is non-resync activity waiting for a turn,
1642          * and resync is going fast enough,
1643          * then let it though before starting on this new sync request.
1644          */
1645         if (!go_faster && conf->nr_waiting)
1646                 msleep_interruptible(1000);
1647
1648         raise_barrier(conf);
1649
1650         conf->next_resync = sector_nr;
1651
1652         r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
1653         rcu_read_lock();
1654         /*
1655          * If we get a correctably read error during resync or recovery,
1656          * we might want to read from a different device.  So we
1657          * flag all drives that could conceivably be read from for READ,
1658          * and any others (which will be non-In_sync devices) for WRITE.
1659          * If a read fails, we try reading from something else for which READ
1660          * is OK.
1661          */
1662
1663         r1_bio->mddev = mddev;
1664         r1_bio->sector = sector_nr;
1665         r1_bio->state = 0;
1666         set_bit(R1BIO_IsSync, &r1_bio->state);
1667
1668         for (i=0; i < conf->raid_disks; i++) {
1669                 mdk_rdev_t *rdev;
1670                 bio = r1_bio->bios[i];
1671
1672                 /* take from bio_init */
1673                 bio->bi_next = NULL;
1674                 bio->bi_flags |= 1 << BIO_UPTODATE;
1675                 bio->bi_rw = 0;
1676                 bio->bi_vcnt = 0;
1677                 bio->bi_idx = 0;
1678                 bio->bi_phys_segments = 0;
1679                 bio->bi_hw_segments = 0;
1680                 bio->bi_size = 0;
1681                 bio->bi_end_io = NULL;
1682                 bio->bi_private = NULL;
1683
1684                 rdev = rcu_dereference(conf->mirrors[i].rdev);
1685                 if (rdev == NULL ||
1686                            test_bit(Faulty, &rdev->flags)) {
1687                         still_degraded = 1;
1688                         continue;
1689                 } else if (!test_bit(In_sync, &rdev->flags)) {
1690                         bio->bi_rw = WRITE;
1691                         bio->bi_end_io = end_sync_write;
1692                         write_targets ++;
1693                 } else {
1694                         /* may need to read from here */
1695                         bio->bi_rw = READ;
1696                         bio->bi_end_io = end_sync_read;
1697                         if (test_bit(WriteMostly, &rdev->flags)) {
1698                                 if (wonly < 0)
1699                                         wonly = i;
1700                         } else {
1701                                 if (disk < 0)
1702                                         disk = i;
1703                         }
1704                         read_targets++;
1705                 }
1706                 atomic_inc(&rdev->nr_pending);
1707                 bio->bi_sector = sector_nr + rdev->data_offset;
1708                 bio->bi_bdev = rdev->bdev;
1709                 bio->bi_private = r1_bio;
1710         }
1711         rcu_read_unlock();
1712         if (disk < 0)
1713                 disk = wonly;
1714         r1_bio->read_disk = disk;
1715
1716         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
1717                 /* extra read targets are also write targets */
1718                 write_targets += read_targets-1;
1719
1720         if (write_targets == 0 || read_targets == 0) {
1721                 /* There is nowhere to write, so all non-sync
1722                  * drives must be failed - so we are finished
1723                  */
1724                 sector_t rv = max_sector - sector_nr;
1725                 *skipped = 1;
1726                 put_buf(r1_bio);
1727                 return rv;
1728         }
1729
1730         nr_sectors = 0;
1731         sync_blocks = 0;
1732         do {
1733                 struct page *page;
1734                 int len = PAGE_SIZE;
1735                 if (sector_nr + (len>>9) > max_sector)
1736                         len = (max_sector - sector_nr) << 9;
1737                 if (len == 0)
1738                         break;
1739                 if (sync_blocks == 0) {
1740                         if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1741                                                &sync_blocks, still_degraded) &&
1742                             !conf->fullsync &&
1743                             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
1744                                 break;
1745                         BUG_ON(sync_blocks < (PAGE_SIZE>>9));
1746                         if (len > (sync_blocks<<9))
1747                                 len = sync_blocks<<9;
1748                 }
1749
1750                 for (i=0 ; i < conf->raid_disks; i++) {
1751                         bio = r1_bio->bios[i];
1752                         if (bio->bi_end_io) {
1753                                 page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
1754                                 if (bio_add_page(bio, page, len, 0) == 0) {
1755                                         /* stop here */
1756                                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
1757                                         while (i > 0) {
1758                                                 i--;
1759                                                 bio = r1_bio->bios[i];
1760                                                 if (bio->bi_end_io==NULL)
1761                                                         continue;
1762                                                 /* remove last page from this bio */
1763                                                 bio->bi_vcnt--;
1764                                                 bio->bi_size -= len;
1765                                                 bio->bi_flags &= ~(1<< BIO_SEG_VALID);
1766                                         }
1767                                         goto bio_full;
1768                                 }
1769                         }
1770                 }
1771                 nr_sectors += len>>9;
1772                 sector_nr += len>>9;
1773                 sync_blocks -= (len>>9);
1774         } while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
1775  bio_full:
1776         r1_bio->sectors = nr_sectors;
1777
1778         /* For a user-requested sync, we read all readable devices and do a
1779          * compare
1780          */
1781         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1782                 atomic_set(&r1_bio->remaining, read_targets);
1783                 for (i=0; i<conf->raid_disks; i++) {
1784                         bio = r1_bio->bios[i];
1785                         if (bio->bi_end_io == end_sync_read) {
1786                                 md_sync_acct(conf->mirrors[i].rdev->bdev, nr_sectors);
1787                                 generic_make_request(bio);
1788                         }
1789                 }
1790         } else {
1791                 atomic_set(&r1_bio->remaining, 1);
1792                 bio = r1_bio->bios[r1_bio->read_disk];
1793                 md_sync_acct(conf->mirrors[r1_bio->read_disk].rdev->bdev,
1794                              nr_sectors);
1795                 generic_make_request(bio);
1796
1797         }
1798
1799         return nr_sectors;
1800 }
1801
1802 static int run(mddev_t *mddev)
1803 {
1804         conf_t *conf;
1805         int i, j, disk_idx;
1806         mirror_info_t *disk;
1807         mdk_rdev_t *rdev;
1808         struct list_head *tmp;
1809
1810         if (mddev->level != 1) {
1811                 printk("raid1: %s: raid level not set to mirroring (%d)\n",
1812                        mdname(mddev), mddev->level);
1813                 goto out;
1814         }
1815         if (mddev->reshape_position != MaxSector) {
1816                 printk("raid1: %s: reshape_position set but not supported\n",
1817                        mdname(mddev));
1818                 goto out;
1819         }
1820         /*
1821          * copy the already verified devices into our private RAID1
1822          * bookkeeping area. [whatever we allocate in run(),
1823          * should be freed in stop()]
1824          */
1825         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
1826         mddev->private = conf;
1827         if (!conf)
1828                 goto out_no_mem;
1829
1830         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
1831                                  GFP_KERNEL);
1832         if (!conf->mirrors)
1833                 goto out_no_mem;
1834
1835         conf->tmppage = alloc_page(GFP_KERNEL);
1836         if (!conf->tmppage)
1837                 goto out_no_mem;
1838
1839         conf->poolinfo = kmalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
1840         if (!conf->poolinfo)
1841                 goto out_no_mem;
1842         conf->poolinfo->mddev = mddev;
1843         conf->poolinfo->raid_disks = mddev->raid_disks;
1844         conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
1845                                           r1bio_pool_free,
1846                                           conf->poolinfo);
1847         if (!conf->r1bio_pool)
1848                 goto out_no_mem;
1849
1850         ITERATE_RDEV(mddev, rdev, tmp) {
1851                 disk_idx = rdev->raid_disk;
1852                 if (disk_idx >= mddev->raid_disks
1853                     || disk_idx < 0)
1854                         continue;
1855                 disk = conf->mirrors + disk_idx;
1856
1857                 disk->rdev = rdev;
1858
1859                 blk_queue_stack_limits(mddev->queue,
1860                                        rdev->bdev->bd_disk->queue);
1861                 /* as we don't honour merge_bvec_fn, we must never risk
1862                  * violating it, so limit ->max_sector to one PAGE, as
1863                  * a one page request is never in violation.
1864                  */
1865                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
1866                     mddev->queue->max_sectors > (PAGE_SIZE>>9))
1867                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
1868
1869                 disk->head_position = 0;
1870                 if (!test_bit(Faulty, &rdev->flags) && test_bit(In_sync, &rdev->flags))
1871                         conf->working_disks++;
1872         }
1873         conf->raid_disks = mddev->raid_disks;
1874         conf->mddev = mddev;
1875         spin_lock_init(&conf->device_lock);
1876         INIT_LIST_HEAD(&conf->retry_list);
1877         if (conf->working_disks == 1)
1878                 mddev->recovery_cp = MaxSector;
1879
1880         spin_lock_init(&conf->resync_lock);
1881         init_waitqueue_head(&conf->wait_barrier);
1882
1883         bio_list_init(&conf->pending_bio_list);
1884         bio_list_init(&conf->flushing_bio_list);
1885
1886         if (!conf->working_disks) {
1887                 printk(KERN_ERR "raid1: no operational mirrors for %s\n",
1888                         mdname(mddev));
1889                 goto out_free_conf;
1890         }
1891
1892         mddev->degraded = 0;
1893         for (i = 0; i < conf->raid_disks; i++) {
1894
1895                 disk = conf->mirrors + i;
1896
1897                 if (!disk->rdev ||
1898                     !test_bit(In_sync, &disk->rdev->flags)) {
1899                         disk->head_position = 0;
1900                         mddev->degraded++;
1901                 }
1902         }
1903
1904         /*
1905          * find the first working one and use it as a starting point
1906          * to read balancing.
1907          */
1908         for (j = 0; j < conf->raid_disks &&
1909                      (!conf->mirrors[j].rdev ||
1910                       !test_bit(In_sync, &conf->mirrors[j].rdev->flags)) ; j++)
1911                 /* nothing */;
1912         conf->last_used = j;
1913
1914
1915         mddev->thread = md_register_thread(raid1d, mddev, "%s_raid1");
1916         if (!mddev->thread) {
1917                 printk(KERN_ERR
1918                        "raid1: couldn't allocate thread for %s\n",
1919                        mdname(mddev));
1920                 goto out_free_conf;
1921         }
1922
1923         printk(KERN_INFO
1924                 "raid1: raid set %s active with %d out of %d mirrors\n",
1925                 mdname(mddev), mddev->raid_disks - mddev->degraded,
1926                 mddev->raid_disks);
1927         /*
1928          * Ok, everything is just fine now
1929          */
1930         mddev->array_size = mddev->size;
1931
1932         mddev->queue->unplug_fn = raid1_unplug;
1933         mddev->queue->issue_flush_fn = raid1_issue_flush;
1934
1935         return 0;
1936
1937 out_no_mem:
1938         printk(KERN_ERR "raid1: couldn't allocate memory for %s\n",
1939                mdname(mddev));
1940
1941 out_free_conf:
1942         if (conf) {
1943                 if (conf->r1bio_pool)
1944                         mempool_destroy(conf->r1bio_pool);
1945                 kfree(conf->mirrors);
1946                 safe_put_page(conf->tmppage);
1947                 kfree(conf->poolinfo);
1948                 kfree(conf);
1949                 mddev->private = NULL;
1950         }
1951 out:
1952         return -EIO;
1953 }
1954
1955 static int stop(mddev_t *mddev)
1956 {
1957         conf_t *conf = mddev_to_conf(mddev);
1958         struct bitmap *bitmap = mddev->bitmap;
1959         int behind_wait = 0;
1960
1961         /* wait for behind writes to complete */
1962         while (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
1963                 behind_wait++;
1964                 printk(KERN_INFO "raid1: behind writes in progress on device %s, waiting to stop (%d)\n", mdname(mddev), behind_wait);
1965                 set_current_state(TASK_UNINTERRUPTIBLE);
1966                 schedule_timeout(HZ); /* wait a second */
1967                 /* need to kick something here to make sure I/O goes? */
1968         }
1969
1970         md_unregister_thread(mddev->thread);
1971         mddev->thread = NULL;
1972         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
1973         if (conf->r1bio_pool)
1974                 mempool_destroy(conf->r1bio_pool);
1975         kfree(conf->mirrors);
1976         kfree(conf->poolinfo);
1977         kfree(conf);
1978         mddev->private = NULL;
1979         return 0;
1980 }
1981
1982 static int raid1_resize(mddev_t *mddev, sector_t sectors)
1983 {
1984         /* no resync is happening, and there is enough space
1985          * on all devices, so we can resize.
1986          * We need to make sure resync covers any new space.
1987          * If the array is shrinking we should possibly wait until
1988          * any io in the removed space completes, but it hardly seems
1989          * worth it.
1990          */
1991         mddev->array_size = sectors>>1;
1992         set_capacity(mddev->gendisk, mddev->array_size << 1);
1993         mddev->changed = 1;
1994         if (mddev->array_size > mddev->size && mddev->recovery_cp == MaxSector) {
1995                 mddev->recovery_cp = mddev->size << 1;
1996                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
1997         }
1998         mddev->size = mddev->array_size;
1999         mddev->resync_max_sectors = sectors;
2000         return 0;
2001 }
2002
2003 static int raid1_reshape(mddev_t *mddev)
2004 {
2005         /* We need to:
2006          * 1/ resize the r1bio_pool
2007          * 2/ resize conf->mirrors
2008          *
2009          * We allocate a new r1bio_pool if we can.
2010          * Then raise a device barrier and wait until all IO stops.
2011          * Then resize conf->mirrors and swap in the new r1bio pool.
2012          *
2013          * At the same time, we "pack" the devices so that all the missing
2014          * devices have the higher raid_disk numbers.
2015          */
2016         mempool_t *newpool, *oldpool;
2017         struct pool_info *newpoolinfo;
2018         mirror_info_t *newmirrors;
2019         conf_t *conf = mddev_to_conf(mddev);
2020         int cnt, raid_disks;
2021
2022         int d, d2;
2023
2024         /* Cannot change chunk_size, layout, or level */
2025         if (mddev->chunk_size != mddev->new_chunk ||
2026             mddev->layout != mddev->new_layout ||
2027             mddev->level != mddev->new_level) {
2028                 mddev->new_chunk = mddev->chunk_size;
2029                 mddev->new_layout = mddev->layout;
2030                 mddev->new_level = mddev->level;
2031                 return -EINVAL;
2032         }
2033
2034         raid_disks = mddev->raid_disks + mddev->delta_disks;
2035
2036         if (raid_disks < conf->raid_disks) {
2037                 cnt=0;
2038                 for (d= 0; d < conf->raid_disks; d++)
2039                         if (conf->mirrors[d].rdev)
2040                                 cnt++;
2041                 if (cnt > raid_disks)
2042                         return -EBUSY;
2043         }
2044
2045         newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
2046         if (!newpoolinfo)
2047                 return -ENOMEM;
2048         newpoolinfo->mddev = mddev;
2049         newpoolinfo->raid_disks = raid_disks;
2050
2051         newpool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2052                                  r1bio_pool_free, newpoolinfo);
2053         if (!newpool) {
2054                 kfree(newpoolinfo);
2055                 return -ENOMEM;
2056         }
2057         newmirrors = kzalloc(sizeof(struct mirror_info) * raid_disks, GFP_KERNEL);
2058         if (!newmirrors) {
2059                 kfree(newpoolinfo);
2060                 mempool_destroy(newpool);
2061                 return -ENOMEM;
2062         }
2063
2064         raise_barrier(conf);
2065
2066         /* ok, everything is stopped */
2067         oldpool = conf->r1bio_pool;
2068         conf->r1bio_pool = newpool;
2069
2070         for (d=d2=0; d < conf->raid_disks; d++)
2071                 if (conf->mirrors[d].rdev) {
2072                         conf->mirrors[d].rdev->raid_disk = d2;
2073                         newmirrors[d2++].rdev = conf->mirrors[d].rdev;
2074                 }
2075         kfree(conf->mirrors);
2076         conf->mirrors = newmirrors;
2077         kfree(conf->poolinfo);
2078         conf->poolinfo = newpoolinfo;
2079
2080         mddev->degraded += (raid_disks - conf->raid_disks);
2081         conf->raid_disks = mddev->raid_disks = raid_disks;
2082         mddev->delta_disks = 0;
2083
2084         conf->last_used = 0; /* just make sure it is in-range */
2085         lower_barrier(conf);
2086
2087         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2088         md_wakeup_thread(mddev->thread);
2089
2090         mempool_destroy(oldpool);
2091         return 0;
2092 }
2093
2094 static void raid1_quiesce(mddev_t *mddev, int state)
2095 {
2096         conf_t *conf = mddev_to_conf(mddev);
2097
2098         switch(state) {
2099         case 1:
2100                 raise_barrier(conf);
2101                 break;
2102         case 0:
2103                 lower_barrier(conf);
2104                 break;
2105         }
2106 }
2107
2108
2109 static struct mdk_personality raid1_personality =
2110 {
2111         .name           = "raid1",
2112         .level          = 1,
2113         .owner          = THIS_MODULE,
2114         .make_request   = make_request,
2115         .run            = run,
2116         .stop           = stop,
2117         .status         = status,
2118         .error_handler  = error,
2119         .hot_add_disk   = raid1_add_disk,
2120         .hot_remove_disk= raid1_remove_disk,
2121         .spare_active   = raid1_spare_active,
2122         .sync_request   = sync_request,
2123         .resize         = raid1_resize,
2124         .check_reshape  = raid1_reshape,
2125         .quiesce        = raid1_quiesce,
2126 };
2127
2128 static int __init raid_init(void)
2129 {
2130         return register_md_personality(&raid1_personality);
2131 }
2132
2133 static void raid_exit(void)
2134 {
2135         unregister_md_personality(&raid1_personality);
2136 }
2137
2138 module_init(raid_init);
2139 module_exit(raid_exit);
2140 MODULE_LICENSE("GPL");
2141 MODULE_ALIAS("md-personality-3"); /* RAID1 */
2142 MODULE_ALIAS("md-raid1");
2143 MODULE_ALIAS("md-level-1");