drivers/md/raid1.c

   1 /*
   2  * raid1.c : Multiple Devices driver for Linux
   3  *
   4  * Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
   5  *
   6  * Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   7  *
   8  * RAID-1 management functions.
   9  *
  10  * Better read-balancing code written by Mika Kuoppala <miku@iki.fi>, 2000
  11  *
  12  * Fixes to reconstruction by Jakob Østergaard" <jakob@ostenfeld.dk>
  13  * Various fixes by Neil Brown <neilb@cse.unsw.edu.au>
  14  *
  15  * Changes by Peter T. Breuer <ptb@it.uc3m.es> 31/1/2003 to support
  16  * bitmapped intelligence in resync:
  17  *
  18  *      - bitmap marked during normal i/o
  19  *      - bitmap used to skip nondirty blocks during sync
  20  *
  21  * Additions to bitmap code, (C) 2003-2004 Paul Clements, SteelEye Technology:
  22  * - persistent bitmap code
  23  *
  24  * This program is free software; you can redistribute it and/or modify
  25  * it under the terms of the GNU General Public License as published by
  26  * the Free Software Foundation; either version 2, or (at your option)
  27  * any later version.
  28  *
  29  * You should have received a copy of the GNU General Public License
  30  * (for example /usr/src/linux/COPYING); if not, write to the Free
  31  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  32  */
  33
  34 #include <linux/delay.h>
  35 #include <linux/blkdev.h>
  36 #include <linux/seq_file.h>
  37 #include "md.h"
  38 #include "raid1.h"
  39 #include "bitmap.h"
  40
  41 #define DEBUG 0
  42 #if DEBUG
  43 #define PRINTK(x...) printk(x)
  44 #else
  45 #define PRINTK(x...)
  46 #endif
  47
  48 /*
  49  * Number of guaranteed r1bios in case of extreme VM load:
  50  */
  51 #define NR_RAID1_BIOS 256
  52
  53
  54 static void unplug_slaves(mddev_t *mddev);
  55
  56 static void allow_barrier(conf_t *conf);
  57 static void lower_barrier(conf_t *conf);
  58
  59 static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
  60 {
  61         struct pool_info *pi = data;
  62         r1bio_t *r1_bio;
  63         int size = offsetof(r1bio_t, bios[pi->raid_disks]);
  64
  65         /* allocate a r1bio with room for raid_disks entries in the bios array */
  66         r1_bio = kzalloc(size, gfp_flags);
  67         if (!r1_bio && pi->mddev)
  68                 unplug_slaves(pi->mddev);
  69
  70         return r1_bio;
  71 }
  72
  73 static void r1bio_pool_free(void *r1_bio, void *data)
  74 {
  75         kfree(r1_bio);
  76 }
  77
  78 #define RESYNC_BLOCK_SIZE (64*1024)
  79 //#define RESYNC_BLOCK_SIZE PAGE_SIZE
  80 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
  81 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
  82 #define RESYNC_WINDOW (2048*1024)
  83
  84 static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
  85 {
  86         struct pool_info *pi = data;
  87         struct page *page;
  88         r1bio_t *r1_bio;
  89         struct bio *bio;
  90         int i, j;
  91
  92         r1_bio = r1bio_pool_alloc(gfp_flags, pi);
  93         if (!r1_bio) {
  94                 unplug_slaves(pi->mddev);
  95                 return NULL;
  96         }
  97
  98         /*
  99          * Allocate bios : 1 for reading, n-1 for writing
 100          */
 101         for (j = pi->raid_disks ; j-- ; ) {
 102                 bio = bio_alloc(gfp_flags, RESYNC_PAGES);
 103                 if (!bio)
 104                         goto out_free_bio;
 105                 r1_bio->bios[j] = bio;
 106         }
 107         /*
 108          * Allocate RESYNC_PAGES data pages and attach them to
 109          * the first bio.
 110          * If this is a user-requested check/repair, allocate
 111          * RESYNC_PAGES for each bio.
 112          */
 113         if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
 114                 j = pi->raid_disks;
 115         else
 116                 j = 1;
 117         while(j--) {
 118                 bio = r1_bio->bios[j];
 119                 for (i = 0; i < RESYNC_PAGES; i++) {
 120                         page = alloc_page(gfp_flags);
 121                         if (unlikely(!page))
 122                                 goto out_free_pages;
 123
 124                         bio->bi_io_vec[i].bv_page = page;
 125                         bio->bi_vcnt = i+1;
 126                 }
 127         }
 128         /* If not user-requests, copy the page pointers to all bios */
 129         if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
 130                 for (i=0; i<RESYNC_PAGES ; i++)
 131                         for (j=1; j<pi->raid_disks; j++)
 132                                 r1_bio->bios[j]->bi_io_vec[i].bv_page =
 133                                         r1_bio->bios[0]->bi_io_vec[i].bv_page;
 134         }
 135
 136         r1_bio->master_bio = NULL;
 137
 138         return r1_bio;
 139
 140 out_free_pages:
 141         for (j=0 ; j < pi->raid_disks; j++)
 142                 for (i=0; i < r1_bio->bios[j]->bi_vcnt ; i++)
 143                         put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
 144         j = -1;
 145 out_free_bio:
 146         while ( ++j < pi->raid_disks )
 147                 bio_put(r1_bio->bios[j]);
 148         r1bio_pool_free(r1_bio, data);
 149         return NULL;
 150 }
 151
 152 static void r1buf_pool_free(void *__r1_bio, void *data)
 153 {
 154         struct pool_info *pi = data;
 155         int i,j;
 156         r1bio_t *r1bio = __r1_bio;
 157
 158         for (i = 0; i < RESYNC_PAGES; i++)
 159                 for (j = pi->raid_disks; j-- ;) {
 160                         if (j == 0 ||
 161                             r1bio->bios[j]->bi_io_vec[i].bv_page !=
 162                             r1bio->bios[0]->bi_io_vec[i].bv_page)
 163                                 safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
 164                 }
 165         for (i=0 ; i < pi->raid_disks; i++)
 166                 bio_put(r1bio->bios[i]);
 167
 168         r1bio_pool_free(r1bio, data);
 169 }
 170
 171 static void put_all_bios(conf_t *conf, r1bio_t *r1_bio)
 172 {
 173         int i;
 174
 175         for (i = 0; i < conf->raid_disks; i++) {
 176                 struct bio **bio = r1_bio->bios + i;
 177                 if (*bio && *bio != IO_BLOCKED)
 178                         bio_put(*bio);
 179                 *bio = NULL;
 180         }
 181 }
 182
 183 static void free_r1bio(r1bio_t *r1_bio)
 184 {
 185         conf_t *conf = r1_bio->mddev->private;
 186
 187         /*
 188          * Wake up any possible resync thread that waits for the device
 189          * to go idle.
 190          */
 191         allow_barrier(conf);
 192
 193         put_all_bios(conf, r1_bio);
 194         mempool_free(r1_bio, conf->r1bio_pool);
 195 }
 196
 197 static void put_buf(r1bio_t *r1_bio)
 198 {
 199         conf_t *conf = r1_bio->mddev->private;
 200         int i;
 201
 202         for (i=0; i<conf->raid_disks; i++) {
 203                 struct bio *bio = r1_bio->bios[i];
 204                 if (bio->bi_end_io)
 205                         rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
 206         }
 207
 208         mempool_free(r1_bio, conf->r1buf_pool);
 209
 210         lower_barrier(conf);
 211 }
 212
 213 static void reschedule_retry(r1bio_t *r1_bio)
 214 {
 215         unsigned long flags;
 216         mddev_t *mddev = r1_bio->mddev;
 217         conf_t *conf = mddev->private;
 218
 219         spin_lock_irqsave(&conf->device_lock, flags);
 220         list_add(&r1_bio->retry_list, &conf->retry_list);
 221         conf->nr_queued ++;
 222         spin_unlock_irqrestore(&conf->device_lock, flags);
 223
 224         wake_up(&conf->wait_barrier);
 225         md_wakeup_thread(mddev->thread);
 226 }
 227
 228 /*
 229  * raid_end_bio_io() is called when we have finished servicing a mirrored
 230  * operation and are ready to return a success/failure code to the buffer
 231  * cache layer.
 232  */
 233 static void raid_end_bio_io(r1bio_t *r1_bio)
 234 {
 235         struct bio *bio = r1_bio->master_bio;
 236
 237         /* if nobody has done the final endio yet, do it now */
 238         if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 239                 PRINTK(KERN_DEBUG "raid1: sync end %s on sectors %llu-%llu\n",
 240                         (bio_data_dir(bio) == WRITE) ? "write" : "read",
 241                         (unsigned long long) bio->bi_sector,
 242                         (unsigned long long) bio->bi_sector +
 243                                 (bio->bi_size >> 9) - 1);
 244
 245                 bio_endio(bio,
 246                         test_bit(R1BIO_Uptodate, &r1_bio->state) ? 0 : -EIO);
 247         }
 248         free_r1bio(r1_bio);
 249 }
 250
 251 /*
 252  * Update disk head position estimator based on IRQ completion info.
 253  */
 254 static inline void update_head_pos(int disk, r1bio_t *r1_bio)
 255 {
 256         conf_t *conf = r1_bio->mddev->private;
 257
 258         conf->mirrors[disk].head_position =
 259                 r1_bio->sector + (r1_bio->sectors);
 260 }
 261
 262 static void raid1_end_read_request(struct bio *bio, int error)
 263 {
 264         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 265         r1bio_t *r1_bio = bio->bi_private;
 266         int mirror;
 267         conf_t *conf = r1_bio->mddev->private;
 268
 269         mirror = r1_bio->read_disk;
 270         /*
 271          * this branch is our 'one mirror IO has finished' event handler:
 272          */
 273         update_head_pos(mirror, r1_bio);
 274
 275         if (uptodate)
 276                 set_bit(R1BIO_Uptodate, &r1_bio->state);
 277         else {
 278                 /* If all other devices have failed, we want to return
 279                  * the error upwards rather than fail the last device.
 280                  * Here we redefine "uptodate" to mean "Don't want to retry"
 281                  */
 282                 unsigned long flags;
 283                 spin_lock_irqsave(&conf->device_lock, flags);
 284                 if (r1_bio->mddev->degraded == conf->raid_disks ||
 285                     (r1_bio->mddev->degraded == conf->raid_disks-1 &&
 286                      !test_bit(Faulty, &conf->mirrors[mirror].rdev->flags)))
 287                         uptodate = 1;
 288                 spin_unlock_irqrestore(&conf->device_lock, flags);
 289         }
 290
 291         if (uptodate)
 292                 raid_end_bio_io(r1_bio);
 293         else {
 294                 /*
 295                  * oops, read error:
 296                  */
 297                 char b[BDEVNAME_SIZE];
 298                 if (printk_ratelimit())
 299                         printk(KERN_ERR "md/raid1:%s: %s: rescheduling sector %llu\n",
 300                                mdname(conf->mddev),
 301                                bdevname(conf->mirrors[mirror].rdev->bdev,b), (unsigned long long)r1_bio->sector);
 302                 reschedule_retry(r1_bio);
 303         }
 304
 305         rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 306 }
 307
 308 static void raid1_end_write_request(struct bio *bio, int error)
 309 {
 310         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 311         r1bio_t *r1_bio = bio->bi_private;
 312         int mirror, behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
 313         conf_t *conf = r1_bio->mddev->private;
 314         struct bio *to_put = NULL;
 315
 316
 317         for (mirror = 0; mirror < conf->raid_disks; mirror++)
 318                 if (r1_bio->bios[mirror] == bio)
 319                         break;
 320
 321         if (error == -EOPNOTSUPP && test_bit(R1BIO_Barrier, &r1_bio->state)) {
 322                 set_bit(BarriersNotsupp, &conf->mirrors[mirror].rdev->flags);
 323                 set_bit(R1BIO_BarrierRetry, &r1_bio->state);
 324                 r1_bio->mddev->barriers_work = 0;
 325                 /* Don't rdev_dec_pending in this branch - keep it for the retry */
 326         } else {
 327                 /*
 328                  * this branch is our 'one mirror IO has finished' event handler:
 329                  */
 330                 r1_bio->bios[mirror] = NULL;
 331                 to_put = bio;
 332                 if (!uptodate) {
 333                         md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
 334                         /* an I/O failed, we can't clear the bitmap */
 335                         set_bit(R1BIO_Degraded, &r1_bio->state);
 336                 } else
 337                         /*
 338                          * Set R1BIO_Uptodate in our master bio, so that
 339                          * we will return a good error code for to the higher
 340                          * levels even if IO on some other mirrored buffer fails.
 341                          *
 342                          * The 'master' represents the composite IO operation to
 343                          * user-side. So if something waits for IO, then it will
 344                          * wait for the 'master' bio.
 345                          */
 346                         set_bit(R1BIO_Uptodate, &r1_bio->state);
 347
 348                 update_head_pos(mirror, r1_bio);
 349
 350                 if (behind) {
 351                         if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
 352                                 atomic_dec(&r1_bio->behind_remaining);
 353
 354                         /* In behind mode, we ACK the master bio once the I/O has safely
 355                          * reached all non-writemostly disks. Setting the Returned bit
 356                          * ensures that this gets done only once -- we don't ever want to
 357                          * return -EIO here, instead we'll wait */
 358
 359                         if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
 360                             test_bit(R1BIO_Uptodate, &r1_bio->state)) {
 361                                 /* Maybe we can return now */
 362                                 if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
 363                                         struct bio *mbio = r1_bio->master_bio;
 364                                         PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
 365                                                (unsigned long long) mbio->bi_sector,
 366                                                (unsigned long long) mbio->bi_sector +
 367                                                (mbio->bi_size >> 9) - 1);
 368                                         bio_endio(mbio, 0);
 369                                 }
 370                         }
 371                 }
 372                 rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 373         }
 374         /*
 375          *
 376          * Let's see if all mirrored write operations have finished
 377          * already.
 378          */
 379         if (atomic_dec_and_test(&r1_bio->remaining)) {
 380                 if (test_bit(R1BIO_BarrierRetry, &r1_bio->state))
 381                         reschedule_retry(r1_bio);
 382                 else {
 383                         /* it really is the end of this request */
 384                         if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
 385                                 /* free extra copy of the data pages */
 386                                 int i = bio->bi_vcnt;
 387                                 while (i--)
 388                                         safe_put_page(bio->bi_io_vec[i].bv_page);
 389                         }
 390                         /* clear the bitmap if all writes complete successfully */
 391                         bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
 392                                         r1_bio->sectors,
 393                                         !test_bit(R1BIO_Degraded, &r1_bio->state),
 394                                         behind);
 395                         md_write_end(r1_bio->mddev);
 396                         raid_end_bio_io(r1_bio);
 397                 }
 398         }
 399
 400         if (to_put)
 401                 bio_put(to_put);
 402 }
 403
 404
 405 /*
 406  * This routine returns the disk from which the requested read should
 407  * be done. There is a per-array 'next expected sequential IO' sector
 408  * number - if this matches on the next IO then we use the last disk.
 409  * There is also a per-disk 'last know head position' sector that is
 410  * maintained from IRQ contexts, both the normal and the resync IO
 411  * completion handlers update this position correctly. If there is no
 412  * perfect sequential match then we pick the disk whose head is closest.
 413  *
 414  * If there are 2 mirrors in the same 2 devices, performance degrades
 415  * because position is mirror, not device based.
 416  *
 417  * The rdev for the device selected will have nr_pending incremented.
 418  */
 419 static int read_balance(conf_t *conf, r1bio_t *r1_bio)
 420 {
 421         const unsigned long this_sector = r1_bio->sector;
 422         int new_disk = conf->last_used, disk = new_disk;
 423         int wonly_disk = -1;
 424         const int sectors = r1_bio->sectors;
 425         sector_t new_distance, current_distance;
 426         mdk_rdev_t *rdev;
 427
 428         rcu_read_lock();
 429         /*
 430          * Check if we can balance. We can balance on the whole
 431          * device if no resync is going on, or below the resync window.
 432          * We take the first readable disk when above the resync window.
 433          */
 434  retry:
 435         if (conf->mddev->recovery_cp < MaxSector &&
 436             (this_sector + sectors >= conf->next_resync)) {
 437                 /* Choose the first operation device, for consistancy */
 438                 new_disk = 0;
 439
 440                 for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 441                      r1_bio->bios[new_disk] == IO_BLOCKED ||
 442                      !rdev || !test_bit(In_sync, &rdev->flags)
 443                              || test_bit(WriteMostly, &rdev->flags);
 444                      rdev = rcu_dereference(conf->mirrors[++new_disk].rdev)) {
 445
 446                         if (rdev && test_bit(In_sync, &rdev->flags) &&
 447                                 r1_bio->bios[new_disk] != IO_BLOCKED)
 448                                 wonly_disk = new_disk;
 449
 450                         if (new_disk == conf->raid_disks - 1) {
 451                                 new_disk = wonly_disk;
 452                                 break;
 453                         }
 454                 }
 455                 goto rb_out;
 456         }
 457
 458
 459         /* make sure the disk is operational */
 460         for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 461              r1_bio->bios[new_disk] == IO_BLOCKED ||
 462              !rdev || !test_bit(In_sync, &rdev->flags) ||
 463                      test_bit(WriteMostly, &rdev->flags);
 464              rdev = rcu_dereference(conf->mirrors[new_disk].rdev)) {
 465
 466                 if (rdev && test_bit(In_sync, &rdev->flags) &&
 467                     r1_bio->bios[new_disk] != IO_BLOCKED)
 468                         wonly_disk = new_disk;
 469
 470                 if (new_disk <= 0)
 471                         new_disk = conf->raid_disks;
 472                 new_disk--;
 473                 if (new_disk == disk) {
 474                         new_disk = wonly_disk;
 475                         break;
 476                 }
 477         }
 478
 479         if (new_disk < 0)
 480                 goto rb_out;
 481
 482         disk = new_disk;
 483         /* now disk == new_disk == starting point for search */
 484
 485         /*
 486          * Don't change to another disk for sequential reads:
 487          */
 488         if (conf->next_seq_sect == this_sector)
 489                 goto rb_out;
 490         if (this_sector == conf->mirrors[new_disk].head_position)
 491                 goto rb_out;
 492
 493         current_distance = abs(this_sector - conf->mirrors[disk].head_position);
 494
 495         /* Find the disk whose head is closest */
 496
 497         do {
 498                 if (disk <= 0)
 499                         disk = conf->raid_disks;
 500                 disk--;
 501
 502                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 503
 504                 if (!rdev || r1_bio->bios[disk] == IO_BLOCKED ||
 505                     !test_bit(In_sync, &rdev->flags) ||
 506                     test_bit(WriteMostly, &rdev->flags))
 507                         continue;
 508
 509                 if (!atomic_read(&rdev->nr_pending)) {
 510                         new_disk = disk;
 511                         break;
 512                 }
 513                 new_distance = abs(this_sector - conf->mirrors[disk].head_position);
 514                 if (new_distance < current_distance) {
 515                         current_distance = new_distance;
 516                         new_disk = disk;
 517                 }
 518         } while (disk != conf->last_used);
 519
 520  rb_out:
 521
 522
 523         if (new_disk >= 0) {
 524                 rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
 525                 if (!rdev)
 526                         goto retry;
 527                 atomic_inc(&rdev->nr_pending);
 528                 if (!test_bit(In_sync, &rdev->flags)) {
 529                         /* cannot risk returning a device that failed
 530                          * before we inc'ed nr_pending
 531                          */
 532                         rdev_dec_pending(rdev, conf->mddev);
 533                         goto retry;
 534                 }
 535                 conf->next_seq_sect = this_sector + sectors;
 536                 conf->last_used = new_disk;
 537         }
 538         rcu_read_unlock();
 539
 540         return new_disk;
 541 }
 542
 543 static void unplug_slaves(mddev_t *mddev)
 544 {
 545         conf_t *conf = mddev->private;
 546         int i;
 547
 548         rcu_read_lock();
 549         for (i=0; i<mddev->raid_disks; i++) {
 550                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 551                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
 552                         struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
 553
 554                         atomic_inc(&rdev->nr_pending);
 555                         rcu_read_unlock();
 556
 557                         blk_unplug(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(struct request_queue *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_congested(void *data, int bits)
 575 {
 576         mddev_t *mddev = data;
 577         conf_t *conf = mddev->private;
 578         int i, ret = 0;
 579
 580         if (mddev_congested(mddev, bits))
 581                 return 1;
 582
 583         rcu_read_lock();
 584         for (i = 0; i < mddev->raid_disks; i++) {
 585                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 586                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 587                         struct request_queue *q = bdev_get_queue(rdev->bdev);
 588
 589                         /* Note the '|| 1' - when read_balance prefers
 590                          * non-congested targets, it can be removed
 591                          */
 592                         if ((bits & (1<<BDI_async_congested)) || 1)
 593                                 ret |= bdi_congested(&q->backing_dev_info, bits);
 594                         else
 595                                 ret &= bdi_congested(&q->backing_dev_info, bits);
 596                 }
 597         }
 598         rcu_read_unlock();
 599         return ret;
 600 }
 601
 602
 603 static int flush_pending_writes(conf_t *conf)
 604 {
 605         /* Any writes that have been queued but are awaiting
 606          * bitmap updates get flushed here.
 607          * We return 1 if any requests were actually submitted.
 608          */
 609         int rv = 0;
 610
 611         spin_lock_irq(&conf->device_lock);
 612
 613         if (conf->pending_bio_list.head) {
 614                 struct bio *bio;
 615                 bio = bio_list_get(&conf->pending_bio_list);
 616                 blk_remove_plug(conf->mddev->queue);
 617                 spin_unlock_irq(&conf->device_lock);
 618                 /* flush any pending bitmap writes to
 619                  * disk before proceeding w/ I/O */
 620                 bitmap_unplug(conf->mddev->bitmap);
 621
 622                 while (bio) { /* submit pending writes */
 623                         struct bio *next = bio->bi_next;
 624                         bio->bi_next = NULL;
 625                         generic_make_request(bio);
 626                         bio = next;
 627                 }
 628                 rv = 1;
 629         } else
 630                 spin_unlock_irq(&conf->device_lock);
 631         return rv;
 632 }
 633
 634 /* Barriers....
 635  * Sometimes we need to suspend IO while we do something else,
 636  * either some resync/recovery, or reconfigure the array.
 637  * To do this we raise a 'barrier'.
 638  * The 'barrier' is a counter that can be raised multiple times
 639  * to count how many activities are happening which preclude
 640  * normal IO.
 641  * We can only raise the barrier if there is no pending IO.
 642  * i.e. if nr_pending == 0.
 643  * We choose only to raise the barrier if no-one is waiting for the
 644  * barrier to go down.  This means that as soon as an IO request
 645  * is ready, no other operations which require a barrier will start
 646  * until the IO request has had a chance.
 647  *
 648  * So: regular IO calls 'wait_barrier'.  When that returns there
 649  *    is no backgroup IO happening,  It must arrange to call
 650  *    allow_barrier when it has finished its IO.
 651  * backgroup IO calls must call raise_barrier.  Once that returns
 652  *    there is no normal IO happeing.  It must arrange to call
 653  *    lower_barrier when the particular background IO completes.
 654  */
 655 #define RESYNC_DEPTH 32
 656
 657 static void raise_barrier(conf_t *conf)
 658 {
 659         spin_lock_irq(&conf->resync_lock);
 660
 661         /* Wait until no block IO is waiting */
 662         wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
 663                             conf->resync_lock,
 664                             raid1_unplug(conf->mddev->queue));
 665
 666         /* block any new IO from starting */
 667         conf->barrier++;
 668
 669         /* No wait for all pending IO to complete */
 670         wait_event_lock_irq(conf->wait_barrier,
 671                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 672                             conf->resync_lock,
 673                             raid1_unplug(conf->mddev->queue));
 674
 675         spin_unlock_irq(&conf->resync_lock);
 676 }
 677
 678 static void lower_barrier(conf_t *conf)
 679 {
 680         unsigned long flags;
 681         BUG_ON(conf->barrier <= 0);
 682         spin_lock_irqsave(&conf->resync_lock, flags);
 683         conf->barrier--;
 684         spin_unlock_irqrestore(&conf->resync_lock, flags);
 685         wake_up(&conf->wait_barrier);
 686 }
 687
 688 static void wait_barrier(conf_t *conf)
 689 {
 690         spin_lock_irq(&conf->resync_lock);
 691         if (conf->barrier) {
 692                 conf->nr_waiting++;
 693                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
 694                                     conf->resync_lock,
 695                                     raid1_unplug(conf->mddev->queue));
 696                 conf->nr_waiting--;
 697         }
 698         conf->nr_pending++;
 699         spin_unlock_irq(&conf->resync_lock);
 700 }
 701
 702 static void allow_barrier(conf_t *conf)
 703 {
 704         unsigned long flags;
 705         spin_lock_irqsave(&conf->resync_lock, flags);
 706         conf->nr_pending--;
 707         spin_unlock_irqrestore(&conf->resync_lock, flags);
 708         wake_up(&conf->wait_barrier);
 709 }
 710
 711 static void freeze_array(conf_t *conf)
 712 {
 713         /* stop syncio and normal IO and wait for everything to
 714          * go quite.
 715          * We increment barrier and nr_waiting, and then
 716          * wait until nr_pending match nr_queued+1
 717          * This is called in the context of one normal IO request
 718          * that has failed. Thus any sync request that might be pending
 719          * will be blocked by nr_pending, and we need to wait for
 720          * pending IO requests to complete or be queued for re-try.
 721          * Thus the number queued (nr_queued) plus this request (1)
 722          * must match the number of pending IOs (nr_pending) before
 723          * we continue.
 724          */
 725         spin_lock_irq(&conf->resync_lock);
 726         conf->barrier++;
 727         conf->nr_waiting++;
 728         wait_event_lock_irq(conf->wait_barrier,
 729                             conf->nr_pending == conf->nr_queued+1,
 730                             conf->resync_lock,
 731                             ({ flush_pending_writes(conf);
 732                                raid1_unplug(conf->mddev->queue); }));
 733         spin_unlock_irq(&conf->resync_lock);
 734 }
 735 static void unfreeze_array(conf_t *conf)
 736 {
 737         /* reverse the effect of the freeze */
 738         spin_lock_irq(&conf->resync_lock);
 739         conf->barrier--;
 740         conf->nr_waiting--;
 741         wake_up(&conf->wait_barrier);
 742         spin_unlock_irq(&conf->resync_lock);
 743 }
 744
 745
 746 /* duplicate the data pages for behind I/O */
 747 static struct page **alloc_behind_pages(struct bio *bio)
 748 {
 749         int i;
 750         struct bio_vec *bvec;
 751         struct page **pages = kzalloc(bio->bi_vcnt * sizeof(struct page *),
 752                                         GFP_NOIO);
 753         if (unlikely(!pages))
 754                 goto do_sync_io;
 755
 756         bio_for_each_segment(bvec, bio, i) {
 757                 pages[i] = alloc_page(GFP_NOIO);
 758                 if (unlikely(!pages[i]))
 759                         goto do_sync_io;
 760                 memcpy(kmap(pages[i]) + bvec->bv_offset,
 761                         kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
 762                 kunmap(pages[i]);
 763                 kunmap(bvec->bv_page);
 764         }
 765
 766         return pages;
 767
 768 do_sync_io:
 769         if (pages)
 770                 for (i = 0; i < bio->bi_vcnt && pages[i]; i++)
 771                         put_page(pages[i]);
 772         kfree(pages);
 773         PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
 774         return NULL;
 775 }
 776
 777 static int make_request(mddev_t *mddev, struct bio * bio)
 778 {
 779         conf_t *conf = mddev->private;
 780         mirror_info_t *mirror;
 781         r1bio_t *r1_bio;
 782         struct bio *read_bio;
 783         int i, targets = 0, disks;
 784         struct bitmap *bitmap;
 785         unsigned long flags;
 786         struct bio_list bl;
 787         struct page **behind_pages = NULL;
 788         const int rw = bio_data_dir(bio);
 789         const bool do_sync = bio_rw_flagged(bio, BIO_RW_SYNCIO);
 790         bool do_barriers;
 791         mdk_rdev_t *blocked_rdev;
 792
 793         /*
 794          * Register the new request and wait if the reconstruction
 795          * thread has put up a bar for new requests.
 796          * Continue immediately if no resync is active currently.
 797          * We test barriers_work *after* md_write_start as md_write_start
 798          * may cause the first superblock write, and that will check out
 799          * if barriers work.
 800          */
 801
 802         md_write_start(mddev, bio); /* wait on superblock update early */
 803
 804         if (bio_data_dir(bio) == WRITE &&
 805             bio->bi_sector + bio->bi_size/512 > mddev->suspend_lo &&
 806             bio->bi_sector < mddev->suspend_hi) {
 807                 /* As the suspend_* range is controlled by
 808                  * userspace, we want an interruptible
 809                  * wait.
 810                  */
 811                 DEFINE_WAIT(w);
 812                 for (;;) {
 813                         flush_signals(current);
 814                         prepare_to_wait(&conf->wait_barrier,
 815                                         &w, TASK_INTERRUPTIBLE);
 816                         if (bio->bi_sector + bio->bi_size/512 <= mddev->suspend_lo ||
 817                             bio->bi_sector >= mddev->suspend_hi)
 818                                 break;
 819                         schedule();
 820                 }
 821                 finish_wait(&conf->wait_barrier, &w);
 822         }
 823         if (unlikely(!mddev->barriers_work &&
 824                      bio_rw_flagged(bio, BIO_RW_BARRIER))) {
 825                 if (rw == WRITE)
 826                         md_write_end(mddev);
 827                 bio_endio(bio, -EOPNOTSUPP);
 828                 return 0;
 829         }
 830
 831         wait_barrier(conf);
 832
 833         bitmap = mddev->bitmap;
 834
 835         /*
 836          * make_request() can abort the operation when READA is being
 837          * used and no empty request is available.
 838          *
 839          */
 840         r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
 841
 842         r1_bio->master_bio = bio;
 843         r1_bio->sectors = bio->bi_size >> 9;
 844         r1_bio->state = 0;
 845         r1_bio->mddev = mddev;
 846         r1_bio->sector = bio->bi_sector;
 847
 848         if (rw == READ) {
 849                 /*
 850                  * read balancing logic:
 851                  */
 852                 int rdisk = read_balance(conf, r1_bio);
 853
 854                 if (rdisk < 0) {
 855                         /* couldn't find anywhere to read from */
 856                         raid_end_bio_io(r1_bio);
 857                         return 0;
 858                 }
 859                 mirror = conf->mirrors + rdisk;
 860
 861                 if (test_bit(WriteMostly, &mirror->rdev->flags) &&
 862                     bitmap) {
 863                         /* Reading from a write-mostly device must
 864                          * take care not to over-take any writes
 865                          * that are 'behind'
 866                          */
 867                         wait_event(bitmap->behind_wait,
 868                                    atomic_read(&bitmap->behind_writes) == 0);
 869                 }
 870                 r1_bio->read_disk = rdisk;
 871
 872                 read_bio = bio_clone(bio, GFP_NOIO);
 873
 874                 r1_bio->bios[rdisk] = read_bio;
 875
 876                 read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
 877                 read_bio->bi_bdev = mirror->rdev->bdev;
 878                 read_bio->bi_end_io = raid1_end_read_request;
 879                 read_bio->bi_rw = READ | (do_sync << BIO_RW_SYNCIO);
 880                 read_bio->bi_private = r1_bio;
 881
 882                 generic_make_request(read_bio);
 883                 return 0;
 884         }
 885
 886         /*
 887          * WRITE:
 888          */
 889         /* first select target devices under spinlock and
 890          * inc refcount on their rdev.  Record them by setting
 891          * bios[x] to bio
 892          */
 893         disks = conf->raid_disks;
 894 #if 0
 895         { static int first=1;
 896         if (first) printk("First Write sector %llu disks %d\n",
 897                           (unsigned long long)r1_bio->sector, disks);
 898         first = 0;
 899         }
 900 #endif
 901  retry_write:
 902         blocked_rdev = NULL;
 903         rcu_read_lock();
 904         for (i = 0;  i < disks; i++) {
 905                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 906                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
 907                         atomic_inc(&rdev->nr_pending);
 908                         blocked_rdev = rdev;
 909                         break;
 910                 }
 911                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 912                         atomic_inc(&rdev->nr_pending);
 913                         if (test_bit(Faulty, &rdev->flags)) {
 914                                 rdev_dec_pending(rdev, mddev);
 915                                 r1_bio->bios[i] = NULL;
 916                         } else {
 917                                 r1_bio->bios[i] = bio;
 918                                 targets++;
 919                         }
 920                 } else
 921                         r1_bio->bios[i] = NULL;
 922         }
 923         rcu_read_unlock();
 924
 925         if (unlikely(blocked_rdev)) {
 926                 /* Wait for this device to become unblocked */
 927                 int j;
 928
 929                 for (j = 0; j < i; j++)
 930                         if (r1_bio->bios[j])
 931                                 rdev_dec_pending(conf->mirrors[j].rdev, mddev);
 932
 933                 allow_barrier(conf);
 934                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
 935                 wait_barrier(conf);
 936                 goto retry_write;
 937         }
 938
 939         BUG_ON(targets == 0); /* we never fail the last device */
 940
 941         if (targets < conf->raid_disks) {
 942                 /* array is degraded, we will not clear the bitmap
 943                  * on I/O completion (see raid1_end_write_request) */
 944                 set_bit(R1BIO_Degraded, &r1_bio->state);
 945         }
 946
 947         /* do behind I/O ?
 948          * Not if there are too many, or cannot allocate memory,
 949          * or a reader on WriteMostly is waiting for behind writes
 950          * to flush */
 951         if (bitmap &&
 952             (atomic_read(&bitmap->behind_writes)
 953              < mddev->bitmap_info.max_write_behind) &&
 954             !waitqueue_active(&bitmap->behind_wait) &&
 955             (behind_pages = alloc_behind_pages(bio)) != NULL)
 956                 set_bit(R1BIO_BehindIO, &r1_bio->state);
 957
 958         atomic_set(&r1_bio->remaining, 0);
 959         atomic_set(&r1_bio->behind_remaining, 0);
 960
 961         do_barriers = bio_rw_flagged(bio, BIO_RW_BARRIER);
 962         if (do_barriers)
 963                 set_bit(R1BIO_Barrier, &r1_bio->state);
 964
 965         bio_list_init(&bl);
 966         for (i = 0; i < disks; i++) {
 967                 struct bio *mbio;
 968                 if (!r1_bio->bios[i])
 969                         continue;
 970
 971                 mbio = bio_clone(bio, GFP_NOIO);
 972                 r1_bio->bios[i] = mbio;
 973
 974                 mbio->bi_sector = r1_bio->sector + conf->mirrors[i].rdev->data_offset;
 975                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
 976                 mbio->bi_end_io = raid1_end_write_request;
 977                 mbio->bi_rw = WRITE | (do_barriers << BIO_RW_BARRIER) |
 978                         (do_sync << BIO_RW_SYNCIO);
 979                 mbio->bi_private = r1_bio;
 980
 981                 if (behind_pages) {
 982                         struct bio_vec *bvec;
 983                         int j;
 984
 985                         /* Yes, I really want the '__' version so that
 986                          * we clear any unused pointer in the io_vec, rather
 987                          * than leave them unchanged.  This is important
 988                          * because when we come to free the pages, we won't
 989                          * know the originial bi_idx, so we just free
 990                          * them all
 991                          */
 992                         __bio_for_each_segment(bvec, mbio, j, 0)
 993                                 bvec->bv_page = behind_pages[j];
 994                         if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
 995                                 atomic_inc(&r1_bio->behind_remaining);
 996                 }
 997
 998                 atomic_inc(&r1_bio->remaining);
 999
1000                 bio_list_add(&bl, mbio);
1001         }
1002         kfree(behind_pages); /* the behind pages are attached to the bios now */
1003
1004         bitmap_startwrite(bitmap, bio->bi_sector, r1_bio->sectors,
1005                                 test_bit(R1BIO_BehindIO, &r1_bio->state));
1006         spin_lock_irqsave(&conf->device_lock, flags);
1007         bio_list_merge(&conf->pending_bio_list, &bl);
1008         bio_list_init(&bl);
1009
1010         blk_plug_device(mddev->queue);
1011         spin_unlock_irqrestore(&conf->device_lock, flags);
1012
1013         /* In case raid1d snuck into freeze_array */
1014         wake_up(&conf->wait_barrier);
1015
1016         if (do_sync)
1017                 md_wakeup_thread(mddev->thread);
1018 #if 0
1019         while ((bio = bio_list_pop(&bl)) != NULL)
1020                 generic_make_request(bio);
1021 #endif
1022
1023         return 0;
1024 }
1025
1026 static void status(struct seq_file *seq, mddev_t *mddev)
1027 {
1028         conf_t *conf = mddev->private;
1029         int i;
1030
1031         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
1032                    conf->raid_disks - mddev->degraded);
1033         rcu_read_lock();
1034         for (i = 0; i < conf->raid_disks; i++) {
1035                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
1036                 seq_printf(seq, "%s",
1037                            rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
1038         }
1039         rcu_read_unlock();
1040         seq_printf(seq, "]");
1041 }
1042
1043
1044 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1045 {
1046         char b[BDEVNAME_SIZE];
1047         conf_t *conf = mddev->private;
1048
1049         /*
1050          * If it is not operational, then we have already marked it as dead
1051          * else if it is the last working disks, ignore the error, let the
1052          * next level up know.
1053          * else mark the drive as failed
1054          */
1055         if (test_bit(In_sync, &rdev->flags)
1056             && (conf->raid_disks - mddev->degraded) == 1) {
1057                 /*
1058                  * Don't fail the drive, act as though we were just a
1059                  * normal single drive.
1060                  * However don't try a recovery from this drive as
1061                  * it is very likely to fail.
1062                  */
1063                 mddev->recovery_disabled = 1;
1064                 return;
1065         }
1066         if (test_and_clear_bit(In_sync, &rdev->flags)) {
1067                 unsigned long flags;
1068                 spin_lock_irqsave(&conf->device_lock, flags);
1069                 mddev->degraded++;
1070                 set_bit(Faulty, &rdev->flags);
1071                 spin_unlock_irqrestore(&conf->device_lock, flags);
1072                 /*
1073                  * if recovery is running, make sure it aborts.
1074                  */
1075                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1076         } else
1077                 set_bit(Faulty, &rdev->flags);
1078         set_bit(MD_CHANGE_DEVS, &mddev->flags);
1079         printk(KERN_ALERT "md/raid1:%s: Disk failure on %s, disabling device.\n"
1080                KERN_ALERT "md/raid1:%s: Operation continuing on %d devices.\n",
1081                mdname(mddev), bdevname(rdev->bdev, b),
1082                mdname(mddev), conf->raid_disks - mddev->degraded);
1083 }
1084
1085 static void print_conf(conf_t *conf)
1086 {
1087         int i;
1088
1089         printk(KERN_DEBUG "RAID1 conf printout:\n");
1090         if (!conf) {
1091                 printk(KERN_DEBUG "(!conf)\n");
1092                 return;
1093         }
1094         printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1095                 conf->raid_disks);
1096
1097         rcu_read_lock();
1098         for (i = 0; i < conf->raid_disks; i++) {
1099                 char b[BDEVNAME_SIZE];
1100                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
1101                 if (rdev)
1102                         printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1103                                i, !test_bit(In_sync, &rdev->flags),
1104                                !test_bit(Faulty, &rdev->flags),
1105                                bdevname(rdev->bdev,b));
1106         }
1107         rcu_read_unlock();
1108 }
1109
1110 static void close_sync(conf_t *conf)
1111 {
1112         wait_barrier(conf);
1113         allow_barrier(conf);
1114
1115         mempool_destroy(conf->r1buf_pool);
1116         conf->r1buf_pool = NULL;
1117 }
1118
1119 static int raid1_spare_active(mddev_t *mddev)
1120 {
1121         int i;
1122         conf_t *conf = mddev->private;
1123
1124         /*
1125          * Find all failed disks within the RAID1 configuration
1126          * and mark them readable.
1127          * Called under mddev lock, so rcu protection not needed.
1128          */
1129         for (i = 0; i < conf->raid_disks; i++) {
1130                 mdk_rdev_t *rdev = conf->mirrors[i].rdev;
1131                 if (rdev
1132                     && !test_bit(Faulty, &rdev->flags)
1133                     && !test_and_set_bit(In_sync, &rdev->flags)) {
1134                         unsigned long flags;
1135                         spin_lock_irqsave(&conf->device_lock, flags);
1136                         mddev->degraded--;
1137                         spin_unlock_irqrestore(&conf->device_lock, flags);
1138                 }
1139         }
1140
1141         print_conf(conf);
1142         return 0;
1143 }
1144
1145
1146 static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1147 {
1148         conf_t *conf = mddev->private;
1149         int err = -EEXIST;
1150         int mirror = 0;
1151         mirror_info_t *p;
1152         int first = 0;
1153         int last = mddev->raid_disks - 1;
1154
1155         if (rdev->raid_disk >= 0)
1156                 first = last = rdev->raid_disk;
1157
1158         for (mirror = first; mirror <= last; mirror++)
1159                 if ( !(p=conf->mirrors+mirror)->rdev) {
1160
1161                         disk_stack_limits(mddev->gendisk, rdev->bdev,
1162                                           rdev->data_offset << 9);
1163                         /* as we don't honour merge_bvec_fn, we must
1164                          * never risk violating it, so limit
1165                          * ->max_segments to one lying with a single
1166                          * page, as a one page request is never in
1167                          * violation.
1168                          */
1169                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
1170                                 blk_queue_max_segments(mddev->queue, 1);
1171                                 blk_queue_segment_boundary(mddev->queue,
1172                                                            PAGE_CACHE_SIZE - 1);
1173                         }
1174
1175                         p->head_position = 0;
1176                         rdev->raid_disk = mirror;
1177                         err = 0;
1178                         /* As all devices are equivalent, we don't need a full recovery
1179                          * if this was recently any drive of the array
1180                          */
1181                         if (rdev->saved_raid_disk < 0)
1182                                 conf->fullsync = 1;
1183                         rcu_assign_pointer(p->rdev, rdev);
1184                         break;
1185                 }
1186         md_integrity_add_rdev(rdev, mddev);
1187         print_conf(conf);
1188         return err;
1189 }
1190
1191 static int raid1_remove_disk(mddev_t *mddev, int number)
1192 {
1193         conf_t *conf = mddev->private;
1194         int err = 0;
1195         mdk_rdev_t *rdev;
1196         mirror_info_t *p = conf->mirrors+ number;
1197
1198         print_conf(conf);
1199         rdev = p->rdev;
1200         if (rdev) {
1201                 if (test_bit(In_sync, &rdev->flags) ||
1202                     atomic_read(&rdev->nr_pending)) {
1203                         err = -EBUSY;
1204                         goto abort;
1205                 }
1206                 /* Only remove non-faulty devices is recovery
1207                  * is not possible.
1208                  */
1209                 if (!test_bit(Faulty, &rdev->flags) &&
1210                     mddev->degraded < conf->raid_disks) {
1211                         err = -EBUSY;
1212                         goto abort;
1213                 }
1214                 p->rdev = NULL;
1215                 synchronize_rcu();
1216                 if (atomic_read(&rdev->nr_pending)) {
1217                         /* lost the race, try later */
1218                         err = -EBUSY;
1219                         p->rdev = rdev;
1220                         goto abort;
1221                 }
1222                 md_integrity_register(mddev);
1223         }
1224 abort:
1225
1226         print_conf(conf);
1227         return err;
1228 }
1229
1230
1231 static void end_sync_read(struct bio *bio, int error)
1232 {
1233         r1bio_t *r1_bio = bio->bi_private;
1234         int i;
1235
1236         for (i=r1_bio->mddev->raid_disks; i--; )
1237                 if (r1_bio->bios[i] == bio)
1238                         break;
1239         BUG_ON(i < 0);
1240         update_head_pos(i, r1_bio);
1241         /*
1242          * we have read a block, now it needs to be re-written,
1243          * or re-read if the read failed.
1244          * We don't do much here, just schedule handling by raid1d
1245          */
1246         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1247                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1248
1249         if (atomic_dec_and_test(&r1_bio->remaining))
1250                 reschedule_retry(r1_bio);
1251 }
1252
1253 static void end_sync_write(struct bio *bio, int error)
1254 {
1255         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1256         r1bio_t *r1_bio = bio->bi_private;
1257         mddev_t *mddev = r1_bio->mddev;
1258         conf_t *conf = mddev->private;
1259         int i;
1260         int mirror=0;
1261
1262         for (i = 0; i < conf->raid_disks; i++)
1263                 if (r1_bio->bios[i] == bio) {
1264                         mirror = i;
1265                         break;
1266                 }
1267         if (!uptodate) {
1268                 int sync_blocks = 0;
1269                 sector_t s = r1_bio->sector;
1270                 long sectors_to_go = r1_bio->sectors;
1271                 /* make sure these bits doesn't get cleared. */
1272                 do {
1273                         bitmap_end_sync(mddev->bitmap, s,
1274                                         &sync_blocks, 1);
1275                         s += sync_blocks;
1276                         sectors_to_go -= sync_blocks;
1277                 } while (sectors_to_go > 0);
1278                 md_error(mddev, conf->mirrors[mirror].rdev);
1279         }
1280
1281         update_head_pos(mirror, r1_bio);
1282
1283         if (atomic_dec_and_test(&r1_bio->remaining)) {
1284                 sector_t s = r1_bio->sectors;
1285                 put_buf(r1_bio);
1286                 md_done_sync(mddev, s, uptodate);
1287         }
1288 }
1289
1290 static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
1291 {
1292         conf_t *conf = mddev->private;
1293         int i;
1294         int disks = conf->raid_disks;
1295         struct bio *bio, *wbio;
1296
1297         bio = r1_bio->bios[r1_bio->read_disk];
1298
1299
1300         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1301                 /* We have read all readable devices.  If we haven't
1302                  * got the block, then there is no hope left.
1303                  * If we have, then we want to do a comparison
1304                  * and skip the write if everything is the same.
1305                  * If any blocks failed to read, then we need to
1306                  * attempt an over-write
1307                  */
1308                 int primary;
1309                 if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
1310                         for (i=0; i<mddev->raid_disks; i++)
1311                                 if (r1_bio->bios[i]->bi_end_io == end_sync_read)
1312                                         md_error(mddev, conf->mirrors[i].rdev);
1313
1314                         md_done_sync(mddev, r1_bio->sectors, 1);
1315                         put_buf(r1_bio);
1316                         return;
1317                 }
1318                 for (primary=0; primary<mddev->raid_disks; primary++)
1319                         if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
1320                             test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
1321                                 r1_bio->bios[primary]->bi_end_io = NULL;
1322                                 rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
1323                                 break;
1324                         }
1325                 r1_bio->read_disk = primary;
1326                 for (i=0; i<mddev->raid_disks; i++)
1327                         if (r1_bio->bios[i]->bi_end_io == end_sync_read) {
1328                                 int j;
1329                                 int vcnt = r1_bio->sectors >> (PAGE_SHIFT- 9);
1330                                 struct bio *pbio = r1_bio->bios[primary];
1331                                 struct bio *sbio = r1_bio->bios[i];
1332
1333                                 if (test_bit(BIO_UPTODATE, &sbio->bi_flags)) {
1334                                         for (j = vcnt; j-- ; ) {
1335                                                 struct page *p, *s;
1336                                                 p = pbio->bi_io_vec[j].bv_page;
1337                                                 s = sbio->bi_io_vec[j].bv_page;
1338                                                 if (memcmp(page_address(p),
1339                                                            page_address(s),
1340                                                            PAGE_SIZE))
1341                                                         break;
1342                                         }
1343                                 } else
1344                                         j = 0;
1345                                 if (j >= 0)
1346                                         mddev->resync_mismatches += r1_bio->sectors;
1347                                 if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
1348                                               && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {
1349                                         sbio->bi_end_io = NULL;
1350                                         rdev_dec_pending(conf->mirrors[i].rdev, mddev);
1351                                 } else {
1352                                         /* fixup the bio for reuse */
1353                                         int size;
1354                                         sbio->bi_vcnt = vcnt;
1355                                         sbio->bi_size = r1_bio->sectors << 9;
1356                                         sbio->bi_idx = 0;
1357                                         sbio->bi_phys_segments = 0;
1358                                         sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1359                                         sbio->bi_flags |= 1 << BIO_UPTODATE;
1360                                         sbio->bi_next = NULL;
1361                                         sbio->bi_sector = r1_bio->sector +
1362                                                 conf->mirrors[i].rdev->data_offset;
1363                                         sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
1364                                         size = sbio->bi_size;
1365                                         for (j = 0; j < vcnt ; j++) {
1366                                                 struct bio_vec *bi;
1367                                                 bi = &sbio->bi_io_vec[j];
1368                                                 bi->bv_offset = 0;
1369                                                 if (size > PAGE_SIZE)
1370                                                         bi->bv_len = PAGE_SIZE;
1371                                                 else
1372                                                         bi->bv_len = size;
1373                                                 size -= PAGE_SIZE;
1374                                                 memcpy(page_address(bi->bv_page),
1375                                                        page_address(pbio->bi_io_vec[j].bv_page),
1376                                                        PAGE_SIZE);
1377                                         }
1378
1379                                 }
1380                         }
1381         }
1382         if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
1383                 /* ouch - failed to read all of that.
1384                  * Try some synchronous reads of other devices to get
1385                  * good data, much like with normal read errors.  Only
1386                  * read into the pages we already have so we don't
1387                  * need to re-issue the read request.
1388                  * We don't need to freeze the array, because being in an
1389                  * active sync request, there is no normal IO, and
1390                  * no overlapping syncs.
1391                  */
1392                 sector_t sect = r1_bio->sector;
1393                 int sectors = r1_bio->sectors;
1394                 int idx = 0;
1395
1396                 while(sectors) {
1397                         int s = sectors;
1398                         int d = r1_bio->read_disk;
1399                         int success = 0;
1400                         mdk_rdev_t *rdev;
1401
1402                         if (s > (PAGE_SIZE>>9))
1403                                 s = PAGE_SIZE >> 9;
1404                         do {
1405                                 if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
1406                                         /* No rcu protection needed here devices
1407                                          * can only be removed when no resync is
1408                                          * active, and resync is currently active
1409                                          */
1410                                         rdev = conf->mirrors[d].rdev;
1411                                         if (sync_page_io(rdev->bdev,
1412                                                          sect + rdev->data_offset,
1413                                                          s<<9,
1414                                                          bio->bi_io_vec[idx].bv_page,
1415                                                          READ)) {
1416                                                 success = 1;
1417                                                 break;
1418                                         }
1419                                 }
1420                                 d++;
1421                                 if (d == conf->raid_disks)
1422                                         d = 0;
1423                         } while (!success && d != r1_bio->read_disk);
1424
1425                         if (success) {
1426                                 int start = d;
1427                                 /* write it back and re-read */
1428                                 set_bit(R1BIO_Uptodate, &r1_bio->state);
1429                                 while (d != r1_bio->read_disk) {
1430                                         if (d == 0)
1431                                                 d = conf->raid_disks;
1432                                         d--;
1433                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1434                                                 continue;
1435                                         rdev = conf->mirrors[d].rdev;
1436                                         atomic_add(s, &rdev->corrected_errors);
1437                                         if (sync_page_io(rdev->bdev,
1438                                                          sect + rdev->data_offset,
1439                                                          s<<9,
1440                                                          bio->bi_io_vec[idx].bv_page,
1441                                                          WRITE) == 0)
1442                                                 md_error(mddev, rdev);
1443                                 }
1444                                 d = start;
1445                                 while (d != r1_bio->read_disk) {
1446                                         if (d == 0)
1447                                                 d = conf->raid_disks;
1448                                         d--;
1449                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
1450                                                 continue;
1451                                         rdev = conf->mirrors[d].rdev;
1452                                         if (sync_page_io(rdev->bdev,
1453                                                          sect + rdev->data_offset,
1454                                                          s<<9,
1455                                                          bio->bi_io_vec[idx].bv_page,
1456                                                          READ) == 0)
1457                                                 md_error(mddev, rdev);
1458                                 }
1459                         } else {
1460                                 char b[BDEVNAME_SIZE];
1461                                 /* Cannot read from anywhere, array is toast */
1462                                 md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
1463                                 printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O read error"
1464                                        " for block %llu\n",
1465                                        mdname(mddev),
1466                                        bdevname(bio->bi_bdev, b),
1467                                        (unsigned long long)r1_bio->sector);
1468                                 md_done_sync(mddev, r1_bio->sectors, 0);
1469                                 put_buf(r1_bio);
1470                                 return;
1471                         }
1472                         sectors -= s;
1473                         sect += s;
1474                         idx ++;
1475                 }
1476         }
1477
1478         /*
1479          * schedule writes
1480          */
1481         atomic_set(&r1_bio->remaining, 1);
1482         for (i = 0; i < disks ; i++) {
1483                 wbio = r1_bio->bios[i];
1484                 if (wbio->bi_end_io == NULL ||
1485                     (wbio->bi_end_io == end_sync_read &&
1486                      (i == r1_bio->read_disk ||
1487                       !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
1488                         continue;
1489
1490                 wbio->bi_rw = WRITE;
1491                 wbio->bi_end_io = end_sync_write;
1492                 atomic_inc(&r1_bio->remaining);
1493                 md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
1494
1495                 generic_make_request(wbio);
1496         }
1497
1498         if (atomic_dec_and_test(&r1_bio->remaining)) {
1499                 /* if we're here, all write(s) have completed, so clean up */
1500                 md_done_sync(mddev, r1_bio->sectors, 1);
1501                 put_buf(r1_bio);
1502         }
1503 }
1504
1505 /*
1506  * This is a kernel thread which:
1507  *
1508  *      1.      Retries failed read operations on working mirrors.
1509  *      2.      Updates the raid superblock when problems encounter.
1510  *      3.      Performs writes following reads for array syncronising.
1511  */
1512
1513 static void fix_read_error(conf_t *conf, int read_disk,
1514                            sector_t sect, int sectors)
1515 {
1516         mddev_t *mddev = conf->mddev;
1517         while(sectors) {
1518                 int s = sectors;
1519                 int d = read_disk;
1520                 int success = 0;
1521                 int start;
1522                 mdk_rdev_t *rdev;
1523
1524                 if (s > (PAGE_SIZE>>9))
1525                         s = PAGE_SIZE >> 9;
1526
1527                 do {
1528                         /* Note: no rcu protection needed here
1529                          * as this is synchronous in the raid1d thread
1530                          * which is the thread that might remove
1531                          * a device.  If raid1d ever becomes multi-threaded....
1532                          */
1533                         rdev = conf->mirrors[d].rdev;
1534                         if (rdev &&
1535                             test_bit(In_sync, &rdev->flags) &&
1536                             sync_page_io(rdev->bdev,
1537                                          sect + rdev->data_offset,
1538                                          s<<9,
1539                                          conf->tmppage, READ))
1540                                 success = 1;
1541                         else {
1542                                 d++;
1543                                 if (d == conf->raid_disks)
1544                                         d = 0;
1545                         }
1546                 } while (!success && d != read_disk);
1547
1548                 if (!success) {
1549                         /* Cannot read from anywhere -- bye bye array */
1550                         md_error(mddev, conf->mirrors[read_disk].rdev);
1551                         break;
1552                 }
1553                 /* write it back and re-read */
1554                 start = d;
1555                 while (d != read_disk) {
1556                         if (d==0)
1557                                 d = conf->raid_disks;
1558                         d--;
1559                         rdev = conf->mirrors[d].rdev;
1560                         if (rdev &&
1561                             test_bit(In_sync, &rdev->flags)) {
1562                                 if (sync_page_io(rdev->bdev,
1563                                                  sect + rdev->data_offset,
1564                                                  s<<9, conf->tmppage, WRITE)
1565                                     == 0)
1566                                         /* Well, this device is dead */
1567                                         md_error(mddev, rdev);
1568                         }
1569                 }
1570                 d = start;
1571                 while (d != read_disk) {
1572                         char b[BDEVNAME_SIZE];
1573                         if (d==0)
1574                                 d = conf->raid_disks;
1575                         d--;
1576                         rdev = conf->mirrors[d].rdev;
1577                         if (rdev &&
1578                             test_bit(In_sync, &rdev->flags)) {
1579                                 if (sync_page_io(rdev->bdev,
1580                                                  sect + rdev->data_offset,
1581                                                  s<<9, conf->tmppage, READ)
1582                                     == 0)
1583                                         /* Well, this device is dead */
1584                                         md_error(mddev, rdev);
1585                                 else {
1586                                         atomic_add(s, &rdev->corrected_errors);
1587                                         printk(KERN_INFO
1588                                                "md/raid1:%s: read error corrected "
1589                                                "(%d sectors at %llu on %s)\n",
1590                                                mdname(mddev), s,
1591                                                (unsigned long long)(sect +
1592                                                    rdev->data_offset),
1593                                                bdevname(rdev->bdev, b));
1594                                 }
1595                         }
1596                 }
1597                 sectors -= s;
1598                 sect += s;
1599         }
1600 }
1601
1602 static void raid1d(mddev_t *mddev)
1603 {
1604         r1bio_t *r1_bio;
1605         struct bio *bio;
1606         unsigned long flags;
1607         conf_t *conf = mddev->private;
1608         struct list_head *head = &conf->retry_list;
1609         int unplug=0;
1610         mdk_rdev_t *rdev;
1611
1612         md_check_recovery(mddev);
1613
1614         for (;;) {
1615                 char b[BDEVNAME_SIZE];
1616
1617                 unplug += flush_pending_writes(conf);
1618
1619                 spin_lock_irqsave(&conf->device_lock, flags);
1620                 if (list_empty(head)) {
1621                         spin_unlock_irqrestore(&conf->device_lock, flags);
1622                         break;
1623                 }
1624                 r1_bio = list_entry(head->prev, r1bio_t, retry_list);
1625                 list_del(head->prev);
1626                 conf->nr_queued--;
1627                 spin_unlock_irqrestore(&conf->device_lock, flags);
1628
1629                 mddev = r1_bio->mddev;
1630                 conf = mddev->private;
1631                 if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
1632                         sync_request_write(mddev, r1_bio);
1633                         unplug = 1;
1634                 } else if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
1635                         /* some requests in the r1bio were BIO_RW_BARRIER
1636                          * requests which failed with -EOPNOTSUPP.  Hohumm..
1637                          * Better resubmit without the barrier.
1638                          * We know which devices to resubmit for, because
1639                          * all others have had their bios[] entry cleared.
1640                          * We already have a nr_pending reference on these rdevs.
1641                          */
1642                         int i;
1643                         const bool do_sync = bio_rw_flagged(r1_bio->master_bio, BIO_RW_SYNCIO);
1644                         clear_bit(R1BIO_BarrierRetry, &r1_bio->state);
1645                         clear_bit(R1BIO_Barrier, &r1_bio->state);
1646                         for (i=0; i < conf->raid_disks; i++)
1647                                 if (r1_bio->bios[i])
1648                                         atomic_inc(&r1_bio->remaining);
1649                         for (i=0; i < conf->raid_disks; i++)
1650                                 if (r1_bio->bios[i]) {
1651                                         struct bio_vec *bvec;
1652                                         int j;
1653
1654                                         bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
1655                                         /* copy pages from the failed bio, as
1656                                          * this might be a write-behind device */
1657                                         __bio_for_each_segment(bvec, bio, j, 0)
1658                                                 bvec->bv_page = bio_iovec_idx(r1_bio->bios[i], j)->bv_page;
1659                                         bio_put(r1_bio->bios[i]);
1660                                         bio->bi_sector = r1_bio->sector +
1661                                                 conf->mirrors[i].rdev->data_offset;
1662                                         bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1663                                         bio->bi_end_io = raid1_end_write_request;
1664                                         bio->bi_rw = WRITE |
1665                                                 (do_sync << BIO_RW_SYNCIO);
1666                                         bio->bi_private = r1_bio;
1667                                         r1_bio->bios[i] = bio;
1668                                         generic_make_request(bio);
1669                                 }
1670                 } else {
1671                         int disk;
1672
1673                         /* we got a read error. Maybe the drive is bad.  Maybe just
1674                          * the block and we can fix it.
1675                          * We freeze all other IO, and try reading the block from
1676                          * other devices.  When we find one, we re-write
1677                          * and check it that fixes the read error.
1678                          * This is all done synchronously while the array is
1679                          * frozen
1680                          */
1681                         if (mddev->ro == 0) {
1682                                 freeze_array(conf);
1683                                 fix_read_error(conf, r1_bio->read_disk,
1684                                                r1_bio->sector,
1685                                                r1_bio->sectors);
1686                                 unfreeze_array(conf);
1687                         } else
1688                                 md_error(mddev,
1689                                          conf->mirrors[r1_bio->read_disk].rdev);
1690
1691                         bio = r1_bio->bios[r1_bio->read_disk];
1692                         if ((disk=read_balance(conf, r1_bio)) == -1) {
1693                                 printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O"
1694                                        " read error for block %llu\n",
1695                                        mdname(mddev),
1696                                        bdevname(bio->bi_bdev,b),
1697                                        (unsigned long long)r1_bio->sector);
1698                                 raid_end_bio_io(r1_bio);
1699                         } else {
1700                                 const bool do_sync = bio_rw_flagged(r1_bio->master_bio, BIO_RW_SYNCIO);
1701                                 r1_bio->bios[r1_bio->read_disk] =
1702                                         mddev->ro ? IO_BLOCKED : NULL;
1703                                 r1_bio->read_disk = disk;
1704                                 bio_put(bio);
1705                                 bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
1706                                 r1_bio->bios[r1_bio->read_disk] = bio;
1707                                 rdev = conf->mirrors[disk].rdev;
1708                                 if (printk_ratelimit())
1709                                         printk(KERN_ERR "md/raid1:%s: redirecting sector %llu to"
1710                                                " other mirror: %s\n",
1711                                                mdname(mddev),
1712                                                (unsigned long long)r1_bio->sector,
1713                                                bdevname(rdev->bdev,b));
1714                                 bio->bi_sector = r1_bio->sector + rdev->data_offset;
1715                                 bio->bi_bdev = rdev->bdev;
1716                                 bio->bi_end_io = raid1_end_read_request;
1717                                 bio->bi_rw = READ | (do_sync << BIO_RW_SYNCIO);
1718                                 bio->bi_private = r1_bio;
1719                                 unplug = 1;
1720                                 generic_make_request(bio);
1721                         }
1722                 }
1723                 cond_resched();
1724         }
1725         if (unplug)
1726                 unplug_slaves(mddev);
1727 }
1728
1729
1730 static int init_resync(conf_t *conf)
1731 {
1732         int buffs;
1733
1734         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1735         BUG_ON(conf->r1buf_pool);
1736         conf->r1buf_pool = mempool_create(buffs, r1buf_pool_alloc, r1buf_pool_free,
1737                                           conf->poolinfo);
1738         if (!conf->r1buf_pool)
1739                 return -ENOMEM;
1740         conf->next_resync = 0;
1741         return 0;
1742 }
1743
1744 /*
1745  * perform a "sync" on one "block"
1746  *
1747  * We need to make sure that no normal I/O request - particularly write
1748  * requests - conflict with active sync requests.
1749  *
1750  * This is achieved by tracking pending requests and a 'barrier' concept
1751  * that can be installed to exclude normal IO requests.
1752  */
1753
1754 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1755 {
1756         conf_t *conf = mddev->private;
1757         r1bio_t *r1_bio;
1758         struct bio *bio;
1759         sector_t max_sector, nr_sectors;
1760         int disk = -1;
1761         int i;
1762         int wonly = -1;
1763         int write_targets = 0, read_targets = 0;
1764         int sync_blocks;
1765         int still_degraded = 0;
1766
1767         if (!conf->r1buf_pool)
1768                 if (init_resync(conf))
1769                         return 0;
1770
1771         max_sector = mddev->dev_sectors;
1772         if (sector_nr >= max_sector) {
1773                 /* If we aborted, we need to abort the
1774                  * sync on the 'current' bitmap chunk (there will
1775                  * only be one in raid1 resync.
1776                  * We can find the current addess in mddev->curr_resync
1777                  */
1778                 if (mddev->curr_resync < max_sector) /* aborted */
1779                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1780                                                 &sync_blocks, 1);
1781                 else /* completed sync */
1782                         conf->fullsync = 0;
1783
1784                 bitmap_close_sync(mddev->bitmap);
1785                 close_sync(conf);
1786                 return 0;
1787         }
1788
1789         if (mddev->bitmap == NULL &&
1790             mddev->recovery_cp == MaxSector &&
1791             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
1792             conf->fullsync == 0) {
1793                 *skipped = 1;
1794                 return max_sector - sector_nr;
1795         }
1796         /* before building a request, check if we can skip these blocks..
1797          * This call the bitmap_start_sync doesn't actually record anything
1798          */
1799         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1800             !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1801                 /* We can skip this block, and probably several more */
1802                 *skipped = 1;
1803                 return sync_blocks;
1804         }
1805         /*
1806          * If there is non-resync activity waiting for a turn,
1807          * and resync is going fast enough,
1808          * then let it though before starting on this new sync request.
1809          */
1810         if (!go_faster && conf->nr_waiting)
1811                 msleep_interruptible(1000);
1812
1813         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
1814         raise_barrier(conf);
1815
1816         conf->next_resync = sector_nr;
1817
1818         r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
1819         rcu_read_lock();
1820         /*
1821          * If we get a correctably read error during resync or recovery,
1822          * we might want to read from a different device.  So we
1823          * flag all drives that could conceivably be read from for READ,
1824          * and any others (which will be non-In_sync devices) for WRITE.
1825          * If a read fails, we try reading from something else for which READ
1826          * is OK.
1827          */
1828
1829         r1_bio->mddev = mddev;
1830         r1_bio->sector = sector_nr;
1831         r1_bio->state = 0;
1832         set_bit(R1BIO_IsSync, &r1_bio->state);
1833
1834         for (i=0; i < conf->raid_disks; i++) {
1835                 mdk_rdev_t *rdev;
1836                 bio = r1_bio->bios[i];
1837
1838                 /* take from bio_init */
1839                 bio->bi_next = NULL;
1840                 bio->bi_flags |= 1 << BIO_UPTODATE;
1841                 bio->bi_rw = READ;
1842                 bio->bi_vcnt = 0;
1843                 bio->bi_idx = 0;
1844                 bio->bi_phys_segments = 0;
1845                 bio->bi_size = 0;
1846                 bio->bi_end_io = NULL;
1847                 bio->bi_private = NULL;
1848
1849                 rdev = rcu_dereference(conf->mirrors[i].rdev);
1850                 if (rdev == NULL ||
1851                            test_bit(Faulty, &rdev->flags)) {
1852                         still_degraded = 1;
1853                         continue;
1854                 } else if (!test_bit(In_sync, &rdev->flags)) {
1855                         bio->bi_rw = WRITE;
1856                         bio->bi_end_io = end_sync_write;
1857                         write_targets ++;
1858                 } else {
1859                         /* may need to read from here */
1860                         bio->bi_rw = READ;
1861                         bio->bi_end_io = end_sync_read;
1862                         if (test_bit(WriteMostly, &rdev->flags)) {
1863                                 if (wonly < 0)
1864                                         wonly = i;
1865                         } else {
1866                                 if (disk < 0)
1867                                         disk = i;
1868                         }
1869                         read_targets++;
1870                 }
1871                 atomic_inc(&rdev->nr_pending);
1872                 bio->bi_sector = sector_nr + rdev->data_offset;
1873                 bio->bi_bdev = rdev->bdev;
1874                 bio->bi_private = r1_bio;
1875         }
1876         rcu_read_unlock();
1877         if (disk < 0)
1878                 disk = wonly;
1879         r1_bio->read_disk = disk;
1880
1881         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
1882                 /* extra read targets are also write targets */
1883                 write_targets += read_targets-1;
1884
1885         if (write_targets == 0 || read_targets == 0) {
1886                 /* There is nowhere to write, so all non-sync
1887                  * drives must be failed - so we are finished
1888                  */
1889                 sector_t rv = max_sector - sector_nr;
1890                 *skipped = 1;
1891                 put_buf(r1_bio);
1892                 return rv;
1893         }
1894
1895         if (max_sector > mddev->resync_max)
1896                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
1897         nr_sectors = 0;
1898         sync_blocks = 0;
1899         do {
1900                 struct page *page;
1901                 int len = PAGE_SIZE;
1902                 if (sector_nr + (len>>9) > max_sector)
1903                         len = (max_sector - sector_nr) << 9;
1904                 if (len == 0)
1905                         break;
1906                 if (sync_blocks == 0) {
1907                         if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1908                                                &sync_blocks, still_degraded) &&
1909                             !conf->fullsync &&
1910                             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
1911                                 break;
1912                         BUG_ON(sync_blocks < (PAGE_SIZE>>9));
1913                         if (len > (sync_blocks<<9))
1914                                 len = sync_blocks<<9;
1915                 }
1916
1917                 for (i=0 ; i < conf->raid_disks; i++) {
1918                         bio = r1_bio->bios[i];
1919                         if (bio->bi_end_io) {
1920                                 page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
1921                                 if (bio_add_page(bio, page, len, 0) == 0) {
1922                                         /* stop here */
1923                                         bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
1924                                         while (i > 0) {
1925                                                 i--;
1926                                                 bio = r1_bio->bios[i];
1927                                                 if (bio->bi_end_io==NULL)
1928                                                         continue;
1929                                                 /* remove last page from this bio */
1930                                                 bio->bi_vcnt--;
1931                                                 bio->bi_size -= len;
1932                                                 bio->bi_flags &= ~(1<< BIO_SEG_VALID);
1933                                         }
1934                                         goto bio_full;
1935                                 }
1936                         }
1937                 }
1938                 nr_sectors += len>>9;
1939                 sector_nr += len>>9;
1940                 sync_blocks -= (len>>9);
1941         } while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
1942  bio_full:
1943         r1_bio->sectors = nr_sectors;
1944
1945         /* For a user-requested sync, we read all readable devices and do a
1946          * compare
1947          */
1948         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1949                 atomic_set(&r1_bio->remaining, read_targets);
1950                 for (i=0; i<conf->raid_disks; i++) {
1951                         bio = r1_bio->bios[i];
1952                         if (bio->bi_end_io == end_sync_read) {
1953                                 md_sync_acct(bio->bi_bdev, nr_sectors);
1954                                 generic_make_request(bio);
1955                         }
1956                 }
1957         } else {
1958                 atomic_set(&r1_bio->remaining, 1);
1959                 bio = r1_bio->bios[r1_bio->read_disk];
1960                 md_sync_acct(bio->bi_bdev, nr_sectors);
1961                 generic_make_request(bio);
1962
1963         }
1964         return nr_sectors;
1965 }
1966
1967 static sector_t raid1_size(mddev_t *mddev, sector_t sectors, int raid_disks)
1968 {
1969         if (sectors)
1970                 return sectors;
1971
1972         return mddev->dev_sectors;
1973 }
1974
1975 static conf_t *setup_conf(mddev_t *mddev)
1976 {
1977         conf_t *conf;
1978         int i;
1979         mirror_info_t *disk;
1980         mdk_rdev_t *rdev;
1981         int err = -ENOMEM;
1982
1983         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
1984         if (!conf)
1985                 goto abort;
1986
1987         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
1988                                  GFP_KERNEL);
1989         if (!conf->mirrors)
1990                 goto abort;
1991
1992         conf->tmppage = alloc_page(GFP_KERNEL);
1993         if (!conf->tmppage)
1994                 goto abort;
1995
1996         conf->poolinfo = kzalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
1997         if (!conf->poolinfo)
1998                 goto abort;
1999         conf->poolinfo->raid_disks = mddev->raid_disks;
2000         conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2001                                           r1bio_pool_free,
2002                                           conf->poolinfo);
2003         if (!conf->r1bio_pool)
2004                 goto abort;
2005
2006         conf->poolinfo->mddev = mddev;
2007
2008         spin_lock_init(&conf->device_lock);
2009         list_for_each_entry(rdev, &mddev->disks, same_set) {
2010                 int disk_idx = rdev->raid_disk;
2011                 if (disk_idx >= mddev->raid_disks
2012                     || disk_idx < 0)
2013                         continue;
2014                 disk = conf->mirrors + disk_idx;
2015
2016                 disk->rdev = rdev;
2017
2018                 disk->head_position = 0;
2019         }
2020         conf->raid_disks = mddev->raid_disks;
2021         conf->mddev = mddev;
2022         INIT_LIST_HEAD(&conf->retry_list);
2023
2024         spin_lock_init(&conf->resync_lock);
2025         init_waitqueue_head(&conf->wait_barrier);
2026
2027         bio_list_init(&conf->pending_bio_list);
2028         bio_list_init(&conf->flushing_bio_list);
2029
2030         conf->last_used = -1;
2031         for (i = 0; i < conf->raid_disks; i++) {
2032
2033                 disk = conf->mirrors + i;
2034
2035                 if (!disk->rdev ||
2036                     !test_bit(In_sync, &disk->rdev->flags)) {
2037                         disk->head_position = 0;
2038                         if (disk->rdev)
2039                                 conf->fullsync = 1;
2040                 } else if (conf->last_used < 0)
2041                         /*
2042                          * The first working device is used as a
2043                          * starting point to read balancing.
2044                          */
2045                         conf->last_used = i;
2046         }
2047
2048         err = -EIO;
2049         if (conf->last_used < 0) {
2050                 printk(KERN_ERR "md/raid1:%s: no operational mirrors\n",
2051                        mdname(mddev));
2052                 goto abort;
2053         }
2054         err = -ENOMEM;
2055         conf->thread = md_register_thread(raid1d, mddev, NULL);
2056         if (!conf->thread) {
2057                 printk(KERN_ERR
2058                        "md/raid1:%s: couldn't allocate thread\n",
2059                        mdname(mddev));
2060                 goto abort;
2061         }
2062
2063         return conf;
2064
2065  abort:
2066         if (conf) {
2067                 if (conf->r1bio_pool)
2068                         mempool_destroy(conf->r1bio_pool);
2069                 kfree(conf->mirrors);
2070                 safe_put_page(conf->tmppage);
2071                 kfree(conf->poolinfo);
2072                 kfree(conf);
2073         }
2074         return ERR_PTR(err);
2075 }
2076
2077 static int run(mddev_t *mddev)
2078 {
2079         conf_t *conf;
2080         int i;
2081         mdk_rdev_t *rdev;
2082
2083         if (mddev->level != 1) {
2084                 printk(KERN_ERR "md/raid1:%s: raid level not set to mirroring (%d)\n",
2085                        mdname(mddev), mddev->level);
2086                 return -EIO;
2087         }
2088         if (mddev->reshape_position != MaxSector) {
2089                 printk(KERN_ERR "md/raid1:%s: reshape_position set but not supported\n",
2090                        mdname(mddev));
2091                 return -EIO;
2092         }
2093         /*
2094          * copy the already verified devices into our private RAID1
2095          * bookkeeping area. [whatever we allocate in run(),
2096          * should be freed in stop()]
2097          */
2098         if (mddev->private == NULL)
2099                 conf = setup_conf(mddev);
2100         else
2101                 conf = mddev->private;
2102
2103         if (IS_ERR(conf))
2104                 return PTR_ERR(conf);
2105
2106         mddev->queue->queue_lock = &conf->device_lock;
2107         list_for_each_entry(rdev, &mddev->disks, same_set) {
2108                 disk_stack_limits(mddev->gendisk, rdev->bdev,
2109                                   rdev->data_offset << 9);
2110                 /* as we don't honour merge_bvec_fn, we must never risk
2111                  * violating it, so limit ->max_segments to 1 lying within
2112                  * a single page, as a one page request is never in violation.
2113                  */
2114                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
2115                         blk_queue_max_segments(mddev->queue, 1);
2116                         blk_queue_segment_boundary(mddev->queue,
2117                                                    PAGE_CACHE_SIZE - 1);
2118                 }
2119         }
2120
2121         mddev->degraded = 0;
2122         for (i=0; i < conf->raid_disks; i++)
2123                 if (conf->mirrors[i].rdev == NULL ||
2124                     !test_bit(In_sync, &conf->mirrors[i].rdev->flags) ||
2125                     test_bit(Faulty, &conf->mirrors[i].rdev->flags))
2126                         mddev->degraded++;
2127
2128         if (conf->raid_disks - mddev->degraded == 1)
2129                 mddev->recovery_cp = MaxSector;
2130
2131         if (mddev->recovery_cp != MaxSector)
2132                 printk(KERN_NOTICE "md/raid1:%s: not clean"
2133                        " -- starting background reconstruction\n",
2134                        mdname(mddev));
2135         printk(KERN_INFO
2136                 "md/raid1:%s: active with %d out of %d mirrors\n",
2137                 mdname(mddev), mddev->raid_disks - mddev->degraded,
2138                 mddev->raid_disks);
2139
2140         /*
2141          * Ok, everything is just fine now
2142          */
2143         mddev->thread = conf->thread;
2144         conf->thread = NULL;
2145         mddev->private = conf;
2146
2147         md_set_array_sectors(mddev, raid1_size(mddev, 0, 0));
2148
2149         mddev->queue->unplug_fn = raid1_unplug;
2150         mddev->queue->backing_dev_info.congested_fn = raid1_congested;
2151         mddev->queue->backing_dev_info.congested_data = mddev;
2152         md_integrity_register(mddev);
2153         return 0;
2154 }
2155
2156 static int stop(mddev_t *mddev)
2157 {
2158         conf_t *conf = mddev->private;
2159         struct bitmap *bitmap = mddev->bitmap;
2160
2161         /* wait for behind writes to complete */
2162         if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
2163                 printk(KERN_INFO "md/raid1:%s: behind writes in progress - waiting to stop.\n",
2164                        mdname(mddev));
2165                 /* need to kick something here to make sure I/O goes? */
2166                 wait_event(bitmap->behind_wait,
2167                            atomic_read(&bitmap->behind_writes) == 0);
2168         }
2169
2170         raise_barrier(conf);
2171         lower_barrier(conf);
2172
2173         md_unregister_thread(mddev->thread);
2174         mddev->thread = NULL;
2175         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2176         if (conf->r1bio_pool)
2177                 mempool_destroy(conf->r1bio_pool);
2178         kfree(conf->mirrors);
2179         kfree(conf->poolinfo);
2180         kfree(conf);
2181         mddev->private = NULL;
2182         return 0;
2183 }
2184
2185 static int raid1_resize(mddev_t *mddev, sector_t sectors)
2186 {
2187         /* no resync is happening, and there is enough space
2188          * on all devices, so we can resize.
2189          * We need to make sure resync covers any new space.
2190          * If the array is shrinking we should possibly wait until
2191          * any io in the removed space completes, but it hardly seems
2192          * worth it.
2193          */
2194         md_set_array_sectors(mddev, raid1_size(mddev, sectors, 0));
2195         if (mddev->array_sectors > raid1_size(mddev, sectors, 0))
2196                 return -EINVAL;
2197         set_capacity(mddev->gendisk, mddev->array_sectors);
2198         revalidate_disk(mddev->gendisk);
2199         if (sectors > mddev->dev_sectors &&
2200             mddev->recovery_cp == MaxSector) {
2201                 mddev->recovery_cp = mddev->dev_sectors;
2202                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2203         }
2204         mddev->dev_sectors = sectors;
2205         mddev->resync_max_sectors = sectors;
2206         return 0;
2207 }
2208
2209 static int raid1_reshape(mddev_t *mddev)
2210 {
2211         /* We need to:
2212          * 1/ resize the r1bio_pool
2213          * 2/ resize conf->mirrors
2214          *
2215          * We allocate a new r1bio_pool if we can.
2216          * Then raise a device barrier and wait until all IO stops.
2217          * Then resize conf->mirrors and swap in the new r1bio pool.
2218          *
2219          * At the same time, we "pack" the devices so that all the missing
2220          * devices have the higher raid_disk numbers.
2221          */
2222         mempool_t *newpool, *oldpool;
2223         struct pool_info *newpoolinfo;
2224         mirror_info_t *newmirrors;
2225         conf_t *conf = mddev->private;
2226         int cnt, raid_disks;
2227         unsigned long flags;
2228         int d, d2, err;
2229
2230         /* Cannot change chunk_size, layout, or level */
2231         if (mddev->chunk_sectors != mddev->new_chunk_sectors ||
2232             mddev->layout != mddev->new_layout ||
2233             mddev->level != mddev->new_level) {
2234                 mddev->new_chunk_sectors = mddev->chunk_sectors;
2235                 mddev->new_layout = mddev->layout;
2236                 mddev->new_level = mddev->level;
2237                 return -EINVAL;
2238         }
2239
2240         err = md_allow_write(mddev);
2241         if (err)
2242                 return err;
2243
2244         raid_disks = mddev->raid_disks + mddev->delta_disks;
2245
2246         if (raid_disks < conf->raid_disks) {
2247                 cnt=0;
2248                 for (d= 0; d < conf->raid_disks; d++)
2249                         if (conf->mirrors[d].rdev)
2250                                 cnt++;
2251                 if (cnt > raid_disks)
2252                         return -EBUSY;
2253         }
2254
2255         newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
2256         if (!newpoolinfo)
2257                 return -ENOMEM;
2258         newpoolinfo->mddev = mddev;
2259         newpoolinfo->raid_disks = raid_disks;
2260
2261         newpool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
2262                                  r1bio_pool_free, newpoolinfo);
2263         if (!newpool) {
2264                 kfree(newpoolinfo);
2265                 return -ENOMEM;
2266         }
2267         newmirrors = kzalloc(sizeof(struct mirror_info) * raid_disks, GFP_KERNEL);
2268         if (!newmirrors) {
2269                 kfree(newpoolinfo);
2270                 mempool_destroy(newpool);
2271                 return -ENOMEM;
2272         }
2273
2274         raise_barrier(conf);
2275
2276         /* ok, everything is stopped */
2277         oldpool = conf->r1bio_pool;
2278         conf->r1bio_pool = newpool;
2279
2280         for (d = d2 = 0; d < conf->raid_disks; d++) {
2281                 mdk_rdev_t *rdev = conf->mirrors[d].rdev;
2282                 if (rdev && rdev->raid_disk != d2) {
2283                         char nm[20];
2284                         sprintf(nm, "rd%d", rdev->raid_disk);
2285                         sysfs_remove_link(&mddev->kobj, nm);
2286                         rdev->raid_disk = d2;
2287                         sprintf(nm, "rd%d", rdev->raid_disk);
2288                         sysfs_remove_link(&mddev->kobj, nm);
2289                         if (sysfs_create_link(&mddev->kobj,
2290                                               &rdev->kobj, nm))
2291                                 printk(KERN_WARNING
2292                                        "md/raid1:%s: cannot register "
2293                                        "%s\n",
2294                                        mdname(mddev), nm);
2295                 }
2296                 if (rdev)
2297                         newmirrors[d2++].rdev = rdev;
2298         }
2299         kfree(conf->mirrors);
2300         conf->mirrors = newmirrors;
2301         kfree(conf->poolinfo);
2302         conf->poolinfo = newpoolinfo;
2303
2304         spin_lock_irqsave(&conf->device_lock, flags);
2305         mddev->degraded += (raid_disks - conf->raid_disks);
2306         spin_unlock_irqrestore(&conf->device_lock, flags);
2307         conf->raid_disks = mddev->raid_disks = raid_disks;
2308         mddev->delta_disks = 0;
2309
2310         conf->last_used = 0; /* just make sure it is in-range */
2311         lower_barrier(conf);
2312
2313         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2314         md_wakeup_thread(mddev->thread);
2315
2316         mempool_destroy(oldpool);
2317         return 0;
2318 }
2319
2320 static void raid1_quiesce(mddev_t *mddev, int state)
2321 {
2322         conf_t *conf = mddev->private;
2323
2324         switch(state) {
2325         case 2: /* wake for suspend */
2326                 wake_up(&conf->wait_barrier);
2327                 break;
2328         case 1:
2329                 raise_barrier(conf);
2330                 break;
2331         case 0:
2332                 lower_barrier(conf);
2333                 break;
2334         }
2335 }
2336
2337 static void *raid1_takeover(mddev_t *mddev)
2338 {
2339         /* raid1 can take over:
2340          *  raid5 with 2 devices, any layout or chunk size
2341          */
2342         if (mddev->level == 5 && mddev->raid_disks == 2) {
2343                 conf_t *conf;
2344                 mddev->new_level = 1;
2345                 mddev->new_layout = 0;
2346                 mddev->new_chunk_sectors = 0;
2347                 conf = setup_conf(mddev);
2348                 if (!IS_ERR(conf))
2349                         conf->barrier = 1;
2350                 return conf;
2351         }
2352         return ERR_PTR(-EINVAL);
2353 }
2354
2355 static struct mdk_personality raid1_personality =
2356 {
2357         .name           = "raid1",
2358         .level          = 1,
2359         .owner          = THIS_MODULE,
2360         .make_request   = make_request,
2361         .run            = run,
2362         .stop           = stop,
2363         .status         = status,
2364         .error_handler  = error,
2365         .hot_add_disk   = raid1_add_disk,
2366         .hot_remove_disk= raid1_remove_disk,
2367         .spare_active   = raid1_spare_active,
2368         .sync_request   = sync_request,
2369         .resize         = raid1_resize,
2370         .size           = raid1_size,
2371         .check_reshape  = raid1_reshape,
2372         .quiesce        = raid1_quiesce,
2373         .takeover       = raid1_takeover,
2374 };
2375
2376 static int __init raid_init(void)
2377 {
2378         return register_md_personality(&raid1_personality);
2379 }
2380
2381 static void raid_exit(void)
2382 {
2383         unregister_md_personality(&raid1_personality);
2384 }
2385
2386 module_init(raid_init);
2387 module_exit(raid_exit);
2388 MODULE_LICENSE("GPL");
2389 MODULE_DESCRIPTION("RAID1 (mirroring) personality for MD");
2390 MODULE_ALIAS("md-personality-3"); /* RAID1 */
2391 MODULE_ALIAS("md-raid1");
2392 MODULE_ALIAS("md-level-1");