drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *
   6  * RAID-5 management functions.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * (for example /usr/src/linux/COPYING); if not, write to the Free
  15  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  16  */
  17
  18
  19 #include <linux/config.h>
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <linux/raid/raid5.h>
  23 #include <linux/highmem.h>
  24 #include <linux/bitops.h>
  25 #include <asm/atomic.h>
  26
  27 #include <linux/raid/bitmap.h>
  28
  29 /*
  30  * Stripe cache
  31  */
  32
  33 #define NR_STRIPES              256
  34 #define STRIPE_SIZE             PAGE_SIZE
  35 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  36 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  37 #define IO_THRESHOLD            1
  38 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  39 #define HASH_MASK               (NR_HASH - 1)
  40
  41 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
  42
  43 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
  44  * order without overlap.  There may be several bio's per stripe+device, and
  45  * a bio could span several devices.
  46  * When walking this list for a particular stripe+device, we must never proceed
  47  * beyond a bio that extends past this device, as the next bio might no longer
  48  * be valid.
  49  * This macro is used to determine the 'next' bio in the list, given the sector
  50  * of the current stripe+device
  51  */
  52 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
  53 /*
  54  * The following can be used to debug the driver
  55  */
  56 #define RAID5_DEBUG     0
  57 #define RAID5_PARANOIA  1
  58 #if RAID5_PARANOIA && defined(CONFIG_SMP)
  59 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
  60 #else
  61 # define CHECK_DEVLOCK()
  62 #endif
  63
  64 #define PRINTK(x...) ((void)(RAID5_DEBUG && printk(x)))
  65 #if RAID5_DEBUG
  66 #define inline
  67 #define __inline__
  68 #endif
  69
  70 static void print_raid5_conf (raid5_conf_t *conf);
  71
  72 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
  73 {
  74         if (atomic_dec_and_test(&sh->count)) {
  75                 if (!list_empty(&sh->lru))
  76                         BUG();
  77                 if (atomic_read(&conf->active_stripes)==0)
  78                         BUG();
  79                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
  80                         if (test_bit(STRIPE_DELAYED, &sh->state))
  81                                 list_add_tail(&sh->lru, &conf->delayed_list);
  82                         else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
  83                                  conf->seq_write == sh->bm_seq)
  84                                 list_add_tail(&sh->lru, &conf->bitmap_list);
  85                         else {
  86                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
  87                                 list_add_tail(&sh->lru, &conf->handle_list);
  88                         }
  89                         md_wakeup_thread(conf->mddev->thread);
  90                 } else {
  91                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
  92                                 atomic_dec(&conf->preread_active_stripes);
  93                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
  94                                         md_wakeup_thread(conf->mddev->thread);
  95                         }
  96                         list_add_tail(&sh->lru, &conf->inactive_list);
  97                         atomic_dec(&conf->active_stripes);
  98                         if (!conf->inactive_blocked ||
  99                             atomic_read(&conf->active_stripes) < (conf->max_nr_stripes*3/4))
 100                                 wake_up(&conf->wait_for_stripe);
 101                 }
 102         }
 103 }
 104 static void release_stripe(struct stripe_head *sh)
 105 {
 106         raid5_conf_t *conf = sh->raid_conf;
 107         unsigned long flags;
 108
 109         spin_lock_irqsave(&conf->device_lock, flags);
 110         __release_stripe(conf, sh);
 111         spin_unlock_irqrestore(&conf->device_lock, flags);
 112 }
 113
 114 static inline void remove_hash(struct stripe_head *sh)
 115 {
 116         PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 117
 118         hlist_del_init(&sh->hash);
 119 }
 120
 121 static void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
 122 {
 123         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 124
 125         PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 126
 127         CHECK_DEVLOCK();
 128         hlist_add_head(&sh->hash, hp);
 129 }
 130
 131
 132 /* find an idle stripe, make sure it is unhashed, and return it. */
 133 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
 134 {
 135         struct stripe_head *sh = NULL;
 136         struct list_head *first;
 137
 138         CHECK_DEVLOCK();
 139         if (list_empty(&conf->inactive_list))
 140                 goto out;
 141         first = conf->inactive_list.next;
 142         sh = list_entry(first, struct stripe_head, lru);
 143         list_del_init(first);
 144         remove_hash(sh);
 145         atomic_inc(&conf->active_stripes);
 146 out:
 147         return sh;
 148 }
 149
 150 static void shrink_buffers(struct stripe_head *sh, int num)
 151 {
 152         struct page *p;
 153         int i;
 154
 155         for (i=0; i<num ; i++) {
 156                 p = sh->dev[i].page;
 157                 if (!p)
 158                         continue;
 159                 sh->dev[i].page = NULL;
 160                 put_page(p);
 161         }
 162 }
 163
 164 static int grow_buffers(struct stripe_head *sh, int num)
 165 {
 166         int i;
 167
 168         for (i=0; i<num; i++) {
 169                 struct page *page;
 170
 171                 if (!(page = alloc_page(GFP_KERNEL))) {
 172                         return 1;
 173                 }
 174                 sh->dev[i].page = page;
 175         }
 176         return 0;
 177 }
 178
 179 static void raid5_build_block (struct stripe_head *sh, int i);
 180
 181 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
 182 {
 183         raid5_conf_t *conf = sh->raid_conf;
 184         int i;
 185
 186         if (atomic_read(&sh->count) != 0)
 187                 BUG();
 188         if (test_bit(STRIPE_HANDLE, &sh->state))
 189                 BUG();
 190
 191         CHECK_DEVLOCK();
 192         PRINTK("init_stripe called, stripe %llu\n",
 193                 (unsigned long long)sh->sector);
 194
 195         remove_hash(sh);
 196
 197         sh->sector = sector;
 198         sh->pd_idx = pd_idx;
 199         sh->state = 0;
 200
 201         sh->disks = disks;
 202
 203         for (i = sh->disks; i--; ) {
 204                 struct r5dev *dev = &sh->dev[i];
 205
 206                 if (dev->toread || dev->towrite || dev->written ||
 207                     test_bit(R5_LOCKED, &dev->flags)) {
 208                         printk("sector=%llx i=%d %p %p %p %d\n",
 209                                (unsigned long long)sh->sector, i, dev->toread,
 210                                dev->towrite, dev->written,
 211                                test_bit(R5_LOCKED, &dev->flags));
 212                         BUG();
 213                 }
 214                 dev->flags = 0;
 215                 raid5_build_block(sh, i);
 216         }
 217         insert_hash(conf, sh);
 218 }
 219
 220 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
 221 {
 222         struct stripe_head *sh;
 223         struct hlist_node *hn;
 224
 225         CHECK_DEVLOCK();
 226         PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
 227         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
 228                 if (sh->sector == sector && sh->disks == disks)
 229                         return sh;
 230         PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
 231         return NULL;
 232 }
 233
 234 static void unplug_slaves(mddev_t *mddev);
 235 static void raid5_unplug_device(request_queue_t *q);
 236
 237 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
 238                                              int pd_idx, int noblock)
 239 {
 240         struct stripe_head *sh;
 241
 242         PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
 243
 244         spin_lock_irq(&conf->device_lock);
 245
 246         do {
 247                 wait_event_lock_irq(conf->wait_for_stripe,
 248                                     conf->quiesce == 0,
 249                                     conf->device_lock, /* nothing */);
 250                 sh = __find_stripe(conf, sector, disks);
 251                 if (!sh) {
 252                         if (!conf->inactive_blocked)
 253                                 sh = get_free_stripe(conf);
 254                         if (noblock && sh == NULL)
 255                                 break;
 256                         if (!sh) {
 257                                 conf->inactive_blocked = 1;
 258                                 wait_event_lock_irq(conf->wait_for_stripe,
 259                                                     !list_empty(&conf->inactive_list) &&
 260                                                     (atomic_read(&conf->active_stripes)
 261                                                      < (conf->max_nr_stripes *3/4)
 262                                                      || !conf->inactive_blocked),
 263                                                     conf->device_lock,
 264                                                     unplug_slaves(conf->mddev);
 265                                         );
 266                                 conf->inactive_blocked = 0;
 267                         } else
 268                                 init_stripe(sh, sector, pd_idx, disks);
 269                 } else {
 270                         if (atomic_read(&sh->count)) {
 271                                 if (!list_empty(&sh->lru))
 272                                         BUG();
 273                         } else {
 274                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 275                                         atomic_inc(&conf->active_stripes);
 276                                 if (list_empty(&sh->lru))
 277                                         BUG();
 278                                 list_del_init(&sh->lru);
 279                         }
 280                 }
 281         } while (sh == NULL);
 282
 283         if (sh)
 284                 atomic_inc(&sh->count);
 285
 286         spin_unlock_irq(&conf->device_lock);
 287         return sh;
 288 }
 289
 290 static int grow_one_stripe(raid5_conf_t *conf)
 291 {
 292         struct stripe_head *sh;
 293         sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
 294         if (!sh)
 295                 return 0;
 296         memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
 297         sh->raid_conf = conf;
 298         spin_lock_init(&sh->lock);
 299
 300         if (grow_buffers(sh, conf->raid_disks)) {
 301                 shrink_buffers(sh, conf->raid_disks);
 302                 kmem_cache_free(conf->slab_cache, sh);
 303                 return 0;
 304         }
 305         sh->disks = conf->raid_disks;
 306         /* we just created an active stripe so... */
 307         atomic_set(&sh->count, 1);
 308         atomic_inc(&conf->active_stripes);
 309         INIT_LIST_HEAD(&sh->lru);
 310         release_stripe(sh);
 311         return 1;
 312 }
 313
 314 static int grow_stripes(raid5_conf_t *conf, int num)
 315 {
 316         kmem_cache_t *sc;
 317         int devs = conf->raid_disks;
 318
 319         sprintf(conf->cache_name[0], "raid5/%s", mdname(conf->mddev));
 320         sprintf(conf->cache_name[1], "raid5/%s-alt", mdname(conf->mddev));
 321         conf->active_name = 0;
 322         sc = kmem_cache_create(conf->cache_name[conf->active_name],
 323                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
 324                                0, 0, NULL, NULL);
 325         if (!sc)
 326                 return 1;
 327         conf->slab_cache = sc;
 328         conf->pool_size = devs;
 329         while (num--) {
 330                 if (!grow_one_stripe(conf))
 331                         return 1;
 332         }
 333         return 0;
 334 }
 335 static int resize_stripes(raid5_conf_t *conf, int newsize)
 336 {
 337         /* Make all the stripes able to hold 'newsize' devices.
 338          * New slots in each stripe get 'page' set to a new page.
 339          *
 340          * This happens in stages:
 341          * 1/ create a new kmem_cache and allocate the required number of
 342          *    stripe_heads.
 343          * 2/ gather all the old stripe_heads and tranfer the pages across
 344          *    to the new stripe_heads.  This will have the side effect of
 345          *    freezing the array as once all stripe_heads have been collected,
 346          *    no IO will be possible.  Old stripe heads are freed once their
 347          *    pages have been transferred over, and the old kmem_cache is
 348          *    freed when all stripes are done.
 349          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
 350          *    we simple return a failre status - no need to clean anything up.
 351          * 4/ allocate new pages for the new slots in the new stripe_heads.
 352          *    If this fails, we don't bother trying the shrink the
 353          *    stripe_heads down again, we just leave them as they are.
 354          *    As each stripe_head is processed the new one is released into
 355          *    active service.
 356          *
 357          * Once step2 is started, we cannot afford to wait for a write,
 358          * so we use GFP_NOIO allocations.
 359          */
 360         struct stripe_head *osh, *nsh;
 361         LIST_HEAD(newstripes);
 362         struct disk_info *ndisks;
 363         int err = 0;
 364         kmem_cache_t *sc;
 365         int i;
 366
 367         if (newsize <= conf->pool_size)
 368                 return 0; /* never bother to shrink */
 369
 370         /* Step 1 */
 371         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
 372                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
 373                                0, 0, NULL, NULL);
 374         if (!sc)
 375                 return -ENOMEM;
 376
 377         for (i = conf->max_nr_stripes; i; i--) {
 378                 nsh = kmem_cache_alloc(sc, GFP_KERNEL);
 379                 if (!nsh)
 380                         break;
 381
 382                 memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
 383
 384                 nsh->raid_conf = conf;
 385                 spin_lock_init(&nsh->lock);
 386
 387                 list_add(&nsh->lru, &newstripes);
 388         }
 389         if (i) {
 390                 /* didn't get enough, give up */
 391                 while (!list_empty(&newstripes)) {
 392                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
 393                         list_del(&nsh->lru);
 394                         kmem_cache_free(sc, nsh);
 395                 }
 396                 kmem_cache_destroy(sc);
 397                 return -ENOMEM;
 398         }
 399         /* Step 2 - Must use GFP_NOIO now.
 400          * OK, we have enough stripes, start collecting inactive
 401          * stripes and copying them over
 402          */
 403         list_for_each_entry(nsh, &newstripes, lru) {
 404                 spin_lock_irq(&conf->device_lock);
 405                 wait_event_lock_irq(conf->wait_for_stripe,
 406                                     !list_empty(&conf->inactive_list),
 407                                     conf->device_lock,
 408                                     unplug_slaves(conf->mddev);
 409                         );
 410                 osh = get_free_stripe(conf);
 411                 spin_unlock_irq(&conf->device_lock);
 412                 atomic_set(&nsh->count, 1);
 413                 for(i=0; i<conf->pool_size; i++)
 414                         nsh->dev[i].page = osh->dev[i].page;
 415                 for( ; i<newsize; i++)
 416                         nsh->dev[i].page = NULL;
 417                 kmem_cache_free(conf->slab_cache, osh);
 418         }
 419         kmem_cache_destroy(conf->slab_cache);
 420
 421         /* Step 3.
 422          * At this point, we are holding all the stripes so the array
 423          * is completely stalled, so now is a good time to resize
 424          * conf->disks.
 425          */
 426         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
 427         if (ndisks) {
 428                 for (i=0; i<conf->raid_disks; i++)
 429                         ndisks[i] = conf->disks[i];
 430                 kfree(conf->disks);
 431                 conf->disks = ndisks;
 432         } else
 433                 err = -ENOMEM;
 434
 435         /* Step 4, return new stripes to service */
 436         while(!list_empty(&newstripes)) {
 437                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
 438                 list_del_init(&nsh->lru);
 439                 for (i=conf->raid_disks; i < newsize; i++)
 440                         if (nsh->dev[i].page == NULL) {
 441                                 struct page *p = alloc_page(GFP_NOIO);
 442                                 nsh->dev[i].page = p;
 443                                 if (!p)
 444                                         err = -ENOMEM;
 445                         }
 446                 release_stripe(nsh);
 447         }
 448         /* critical section pass, GFP_NOIO no longer needed */
 449
 450         conf->slab_cache = sc;
 451         conf->active_name = 1-conf->active_name;
 452         conf->pool_size = newsize;
 453         return err;
 454 }
 455
 456
 457 static int drop_one_stripe(raid5_conf_t *conf)
 458 {
 459         struct stripe_head *sh;
 460
 461         spin_lock_irq(&conf->device_lock);
 462         sh = get_free_stripe(conf);
 463         spin_unlock_irq(&conf->device_lock);
 464         if (!sh)
 465                 return 0;
 466         if (atomic_read(&sh->count))
 467                 BUG();
 468         shrink_buffers(sh, conf->pool_size);
 469         kmem_cache_free(conf->slab_cache, sh);
 470         atomic_dec(&conf->active_stripes);
 471         return 1;
 472 }
 473
 474 static void shrink_stripes(raid5_conf_t *conf)
 475 {
 476         while (drop_one_stripe(conf))
 477                 ;
 478
 479         if (conf->slab_cache)
 480                 kmem_cache_destroy(conf->slab_cache);
 481         conf->slab_cache = NULL;
 482 }
 483
 484 static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done,
 485                                    int error)
 486 {
 487         struct stripe_head *sh = bi->bi_private;
 488         raid5_conf_t *conf = sh->raid_conf;
 489         int disks = sh->disks, i;
 490         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 491
 492         if (bi->bi_size)
 493                 return 1;
 494
 495         for (i=0 ; i<disks; i++)
 496                 if (bi == &sh->dev[i].req)
 497                         break;
 498
 499         PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n",
 500                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
 501                 uptodate);
 502         if (i == disks) {
 503                 BUG();
 504                 return 0;
 505         }
 506
 507         if (uptodate) {
 508 #if 0
 509                 struct bio *bio;
 510                 unsigned long flags;
 511                 spin_lock_irqsave(&conf->device_lock, flags);
 512                 /* we can return a buffer if we bypassed the cache or
 513                  * if the top buffer is not in highmem.  If there are
 514                  * multiple buffers, leave the extra work to
 515                  * handle_stripe
 516                  */
 517                 buffer = sh->bh_read[i];
 518                 if (buffer &&
 519                     (!PageHighMem(buffer->b_page)
 520                      || buffer->b_page == bh->b_page )
 521                         ) {
 522                         sh->bh_read[i] = buffer->b_reqnext;
 523                         buffer->b_reqnext = NULL;
 524                 } else
 525                         buffer = NULL;
 526                 spin_unlock_irqrestore(&conf->device_lock, flags);
 527                 if (sh->bh_page[i]==bh->b_page)
 528                         set_buffer_uptodate(bh);
 529                 if (buffer) {
 530                         if (buffer->b_page != bh->b_page)
 531                                 memcpy(buffer->b_data, bh->b_data, bh->b_size);
 532                         buffer->b_end_io(buffer, 1);
 533                 }
 534 #else
 535                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
 536 #endif
 537                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
 538                         printk(KERN_INFO "raid5: read error corrected!!\n");
 539                         clear_bit(R5_ReadError, &sh->dev[i].flags);
 540                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
 541                 }
 542                 if (atomic_read(&conf->disks[i].rdev->read_errors))
 543                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
 544         } else {
 545                 int retry = 0;
 546                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
 547                 atomic_inc(&conf->disks[i].rdev->read_errors);
 548                 if (conf->mddev->degraded)
 549                         printk(KERN_WARNING "raid5: read error not correctable.\n");
 550                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
 551                         /* Oh, no!!! */
 552                         printk(KERN_WARNING "raid5: read error NOT corrected!!\n");
 553                 else if (atomic_read(&conf->disks[i].rdev->read_errors)
 554                          > conf->max_nr_stripes)
 555                         printk(KERN_WARNING
 556                                "raid5: Too many read errors, failing device.\n");
 557                 else
 558                         retry = 1;
 559                 if (retry)
 560                         set_bit(R5_ReadError, &sh->dev[i].flags);
 561                 else {
 562                         clear_bit(R5_ReadError, &sh->dev[i].flags);
 563                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
 564                         md_error(conf->mddev, conf->disks[i].rdev);
 565                 }
 566         }
 567         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 568 #if 0
 569         /* must restore b_page before unlocking buffer... */
 570         if (sh->bh_page[i] != bh->b_page) {
 571                 bh->b_page = sh->bh_page[i];
 572                 bh->b_data = page_address(bh->b_page);
 573                 clear_buffer_uptodate(bh);
 574         }
 575 #endif
 576         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 577         set_bit(STRIPE_HANDLE, &sh->state);
 578         release_stripe(sh);
 579         return 0;
 580 }
 581
 582 static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
 583                                     int error)
 584 {
 585         struct stripe_head *sh = bi->bi_private;
 586         raid5_conf_t *conf = sh->raid_conf;
 587         int disks = sh->disks, i;
 588         unsigned long flags;
 589         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 590
 591         if (bi->bi_size)
 592                 return 1;
 593
 594         for (i=0 ; i<disks; i++)
 595                 if (bi == &sh->dev[i].req)
 596                         break;
 597
 598         PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n",
 599                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
 600                 uptodate);
 601         if (i == disks) {
 602                 BUG();
 603                 return 0;
 604         }
 605
 606         spin_lock_irqsave(&conf->device_lock, flags);
 607         if (!uptodate)
 608                 md_error(conf->mddev, conf->disks[i].rdev);
 609
 610         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 611
 612         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 613         set_bit(STRIPE_HANDLE, &sh->state);
 614         __release_stripe(conf, sh);
 615         spin_unlock_irqrestore(&conf->device_lock, flags);
 616         return 0;
 617 }
 618
 619
 620 static sector_t compute_blocknr(struct stripe_head *sh, int i);
 621
 622 static void raid5_build_block (struct stripe_head *sh, int i)
 623 {
 624         struct r5dev *dev = &sh->dev[i];
 625
 626         bio_init(&dev->req);
 627         dev->req.bi_io_vec = &dev->vec;
 628         dev->req.bi_vcnt++;
 629         dev->req.bi_max_vecs++;
 630         dev->vec.bv_page = dev->page;
 631         dev->vec.bv_len = STRIPE_SIZE;
 632         dev->vec.bv_offset = 0;
 633
 634         dev->req.bi_sector = sh->sector;
 635         dev->req.bi_private = sh;
 636
 637         dev->flags = 0;
 638         if (i != sh->pd_idx)
 639                 dev->sector = compute_blocknr(sh, i);
 640 }
 641
 642 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 643 {
 644         char b[BDEVNAME_SIZE];
 645         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
 646         PRINTK("raid5: error called\n");
 647
 648         if (!test_bit(Faulty, &rdev->flags)) {
 649                 mddev->sb_dirty = 1;
 650                 if (test_bit(In_sync, &rdev->flags)) {
 651                         conf->working_disks--;
 652                         mddev->degraded++;
 653                         conf->failed_disks++;
 654                         clear_bit(In_sync, &rdev->flags);
 655                         /*
 656                          * if recovery was running, make sure it aborts.
 657                          */
 658                         set_bit(MD_RECOVERY_ERR, &mddev->recovery);
 659                 }
 660                 set_bit(Faulty, &rdev->flags);
 661                 printk (KERN_ALERT
 662                         "raid5: Disk failure on %s, disabling device."
 663                         " Operation continuing on %d devices\n",
 664                         bdevname(rdev->bdev,b), conf->working_disks);
 665         }
 666 }
 667
 668 /*
 669  * Input: a 'big' sector number,
 670  * Output: index of the data and parity disk, and the sector # in them.
 671  */
 672 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
 673                         unsigned int data_disks, unsigned int * dd_idx,
 674                         unsigned int * pd_idx, raid5_conf_t *conf)
 675 {
 676         long stripe;
 677         unsigned long chunk_number;
 678         unsigned int chunk_offset;
 679         sector_t new_sector;
 680         int sectors_per_chunk = conf->chunk_size >> 9;
 681
 682         /* First compute the information on this sector */
 683
 684         /*
 685          * Compute the chunk number and the sector offset inside the chunk
 686          */
 687         chunk_offset = sector_div(r_sector, sectors_per_chunk);
 688         chunk_number = r_sector;
 689         BUG_ON(r_sector != chunk_number);
 690
 691         /*
 692          * Compute the stripe number
 693          */
 694         stripe = chunk_number / data_disks;
 695
 696         /*
 697          * Compute the data disk and parity disk indexes inside the stripe
 698          */
 699         *dd_idx = chunk_number % data_disks;
 700
 701         /*
 702          * Select the parity disk based on the user selected algorithm.
 703          */
 704         if (conf->level == 4)
 705                 *pd_idx = data_disks;
 706         else switch (conf->algorithm) {
 707                 case ALGORITHM_LEFT_ASYMMETRIC:
 708                         *pd_idx = data_disks - stripe % raid_disks;
 709                         if (*dd_idx >= *pd_idx)
 710                                 (*dd_idx)++;
 711                         break;
 712                 case ALGORITHM_RIGHT_ASYMMETRIC:
 713                         *pd_idx = stripe % raid_disks;
 714                         if (*dd_idx >= *pd_idx)
 715                                 (*dd_idx)++;
 716                         break;
 717                 case ALGORITHM_LEFT_SYMMETRIC:
 718                         *pd_idx = data_disks - stripe % raid_disks;
 719                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
 720                         break;
 721                 case ALGORITHM_RIGHT_SYMMETRIC:
 722                         *pd_idx = stripe % raid_disks;
 723                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
 724                         break;
 725                 default:
 726                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
 727                                 conf->algorithm);
 728         }
 729
 730         /*
 731          * Finally, compute the new sector number
 732          */
 733         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
 734         return new_sector;
 735 }
 736
 737
 738 static sector_t compute_blocknr(struct stripe_head *sh, int i)
 739 {
 740         raid5_conf_t *conf = sh->raid_conf;
 741         int raid_disks = sh->disks, data_disks = raid_disks - 1;
 742         sector_t new_sector = sh->sector, check;
 743         int sectors_per_chunk = conf->chunk_size >> 9;
 744         sector_t stripe;
 745         int chunk_offset;
 746         int chunk_number, dummy1, dummy2, dd_idx = i;
 747         sector_t r_sector;
 748
 749         chunk_offset = sector_div(new_sector, sectors_per_chunk);
 750         stripe = new_sector;
 751         BUG_ON(new_sector != stripe);
 752
 753
 754         switch (conf->algorithm) {
 755                 case ALGORITHM_LEFT_ASYMMETRIC:
 756                 case ALGORITHM_RIGHT_ASYMMETRIC:
 757                         if (i > sh->pd_idx)
 758                                 i--;
 759                         break;
 760                 case ALGORITHM_LEFT_SYMMETRIC:
 761                 case ALGORITHM_RIGHT_SYMMETRIC:
 762                         if (i < sh->pd_idx)
 763                                 i += raid_disks;
 764                         i -= (sh->pd_idx + 1);
 765                         break;
 766                 default:
 767                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
 768                                 conf->algorithm);
 769         }
 770
 771         chunk_number = stripe * data_disks + i;
 772         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
 773
 774         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
 775         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
 776                 printk(KERN_ERR "compute_blocknr: map not correct\n");
 777                 return 0;
 778         }
 779         return r_sector;
 780 }
 781
 782
 783
 784 /*
 785  * Copy data between a page in the stripe cache, and a bio.
 786  * There are no alignment or size guarantees between the page or the
 787  * bio except that there is some overlap.
 788  * All iovecs in the bio must be considered.
 789  */
 790 static void copy_data(int frombio, struct bio *bio,
 791                      struct page *page,
 792                      sector_t sector)
 793 {
 794         char *pa = page_address(page);
 795         struct bio_vec *bvl;
 796         int i;
 797         int page_offset;
 798
 799         if (bio->bi_sector >= sector)
 800                 page_offset = (signed)(bio->bi_sector - sector) * 512;
 801         else
 802                 page_offset = (signed)(sector - bio->bi_sector) * -512;
 803         bio_for_each_segment(bvl, bio, i) {
 804                 int len = bio_iovec_idx(bio,i)->bv_len;
 805                 int clen;
 806                 int b_offset = 0;
 807
 808                 if (page_offset < 0) {
 809                         b_offset = -page_offset;
 810                         page_offset += b_offset;
 811                         len -= b_offset;
 812                 }
 813
 814                 if (len > 0 && page_offset + len > STRIPE_SIZE)
 815                         clen = STRIPE_SIZE - page_offset;
 816                 else clen = len;
 817
 818                 if (clen > 0) {
 819                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
 820                         if (frombio)
 821                                 memcpy(pa+page_offset, ba+b_offset, clen);
 822                         else
 823                                 memcpy(ba+b_offset, pa+page_offset, clen);
 824                         __bio_kunmap_atomic(ba, KM_USER0);
 825                 }
 826                 if (clen < len) /* hit end of page */
 827                         break;
 828                 page_offset +=  len;
 829         }
 830 }
 831
 832 #define check_xor()     do {                                            \
 833                            if (count == MAX_XOR_BLOCKS) {               \
 834                                 xor_block(count, STRIPE_SIZE, ptr);     \
 835                                 count = 1;                              \
 836                            }                                            \
 837                         } while(0)
 838
 839
 840 static void compute_block(struct stripe_head *sh, int dd_idx)
 841 {
 842         int i, count, disks = sh->disks;
 843         void *ptr[MAX_XOR_BLOCKS], *p;
 844
 845         PRINTK("compute_block, stripe %llu, idx %d\n",
 846                 (unsigned long long)sh->sector, dd_idx);
 847
 848         ptr[0] = page_address(sh->dev[dd_idx].page);
 849         memset(ptr[0], 0, STRIPE_SIZE);
 850         count = 1;
 851         for (i = disks ; i--; ) {
 852                 if (i == dd_idx)
 853                         continue;
 854                 p = page_address(sh->dev[i].page);
 855                 if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
 856                         ptr[count++] = p;
 857                 else
 858                         printk(KERN_ERR "compute_block() %d, stripe %llu, %d"
 859                                 " not present\n", dd_idx,
 860                                 (unsigned long long)sh->sector, i);
 861
 862                 check_xor();
 863         }
 864         if (count != 1)
 865                 xor_block(count, STRIPE_SIZE, ptr);
 866         set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
 867 }
 868
 869 static void compute_parity(struct stripe_head *sh, int method)
 870 {
 871         raid5_conf_t *conf = sh->raid_conf;
 872         int i, pd_idx = sh->pd_idx, disks = sh->disks, count;
 873         void *ptr[MAX_XOR_BLOCKS];
 874         struct bio *chosen;
 875
 876         PRINTK("compute_parity, stripe %llu, method %d\n",
 877                 (unsigned long long)sh->sector, method);
 878
 879         count = 1;
 880         ptr[0] = page_address(sh->dev[pd_idx].page);
 881         switch(method) {
 882         case READ_MODIFY_WRITE:
 883                 if (!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags))
 884                         BUG();
 885                 for (i=disks ; i-- ;) {
 886                         if (i==pd_idx)
 887                                 continue;
 888                         if (sh->dev[i].towrite &&
 889                             test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
 890                                 ptr[count++] = page_address(sh->dev[i].page);
 891                                 chosen = sh->dev[i].towrite;
 892                                 sh->dev[i].towrite = NULL;
 893
 894                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 895                                         wake_up(&conf->wait_for_overlap);
 896
 897                                 if (sh->dev[i].written) BUG();
 898                                 sh->dev[i].written = chosen;
 899                                 check_xor();
 900                         }
 901                 }
 902                 break;
 903         case RECONSTRUCT_WRITE:
 904                 memset(ptr[0], 0, STRIPE_SIZE);
 905                 for (i= disks; i-- ;)
 906                         if (i!=pd_idx && sh->dev[i].towrite) {
 907                                 chosen = sh->dev[i].towrite;
 908                                 sh->dev[i].towrite = NULL;
 909
 910                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 911                                         wake_up(&conf->wait_for_overlap);
 912
 913                                 if (sh->dev[i].written) BUG();
 914                                 sh->dev[i].written = chosen;
 915                         }
 916                 break;
 917         case CHECK_PARITY:
 918                 break;
 919         }
 920         if (count>1) {
 921                 xor_block(count, STRIPE_SIZE, ptr);
 922                 count = 1;
 923         }
 924
 925         for (i = disks; i--;)
 926                 if (sh->dev[i].written) {
 927                         sector_t sector = sh->dev[i].sector;
 928                         struct bio *wbi = sh->dev[i].written;
 929                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
 930                                 copy_data(1, wbi, sh->dev[i].page, sector);
 931                                 wbi = r5_next_bio(wbi, sector);
 932                         }
 933
 934                         set_bit(R5_LOCKED, &sh->dev[i].flags);
 935                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
 936                 }
 937
 938         switch(method) {
 939         case RECONSTRUCT_WRITE:
 940         case CHECK_PARITY:
 941                 for (i=disks; i--;)
 942                         if (i != pd_idx) {
 943                                 ptr[count++] = page_address(sh->dev[i].page);
 944                                 check_xor();
 945                         }
 946                 break;
 947         case READ_MODIFY_WRITE:
 948                 for (i = disks; i--;)
 949                         if (sh->dev[i].written) {
 950                                 ptr[count++] = page_address(sh->dev[i].page);
 951                                 check_xor();
 952                         }
 953         }
 954         if (count != 1)
 955                 xor_block(count, STRIPE_SIZE, ptr);
 956
 957         if (method != CHECK_PARITY) {
 958                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 959                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
 960         } else
 961                 clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 962 }
 963
 964 /*
 965  * Each stripe/dev can have one or more bion attached.
 966  * toread/towrite point to the first in a chain.
 967  * The bi_next chain must be in order.
 968  */
 969 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
 970 {
 971         struct bio **bip;
 972         raid5_conf_t *conf = sh->raid_conf;
 973         int firstwrite=0;
 974
 975         PRINTK("adding bh b#%llu to stripe s#%llu\n",
 976                 (unsigned long long)bi->bi_sector,
 977                 (unsigned long long)sh->sector);
 978
 979
 980         spin_lock(&sh->lock);
 981         spin_lock_irq(&conf->device_lock);
 982         if (forwrite) {
 983                 bip = &sh->dev[dd_idx].towrite;
 984                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
 985                         firstwrite = 1;
 986         } else
 987                 bip = &sh->dev[dd_idx].toread;
 988         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
 989                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
 990                         goto overlap;
 991                 bip = & (*bip)->bi_next;
 992         }
 993         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
 994                 goto overlap;
 995
 996         if (*bip && bi->bi_next && (*bip) != bi->bi_next)
 997                 BUG();
 998         if (*bip)
 999                 bi->bi_next = *bip;
1000         *bip = bi;
1001         bi->bi_phys_segments ++;
1002         spin_unlock_irq(&conf->device_lock);
1003         spin_unlock(&sh->lock);
1004
1005         PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n",
1006                 (unsigned long long)bi->bi_sector,
1007                 (unsigned long long)sh->sector, dd_idx);
1008
1009         if (conf->mddev->bitmap && firstwrite) {
1010                 sh->bm_seq = conf->seq_write;
1011                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
1012                                   STRIPE_SECTORS, 0);
1013                 set_bit(STRIPE_BIT_DELAY, &sh->state);
1014         }
1015
1016         if (forwrite) {
1017                 /* check if page is covered */
1018                 sector_t sector = sh->dev[dd_idx].sector;
1019                 for (bi=sh->dev[dd_idx].towrite;
1020                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
1021                              bi && bi->bi_sector <= sector;
1022                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
1023                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
1024                                 sector = bi->bi_sector + (bi->bi_size>>9);
1025                 }
1026                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
1027                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
1028         }
1029         return 1;
1030
1031  overlap:
1032         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1033         spin_unlock_irq(&conf->device_lock);
1034         spin_unlock(&sh->lock);
1035         return 0;
1036 }
1037
1038
1039 /*
1040  * handle_stripe - do things to a stripe.
1041  *
1042  * We lock the stripe and then examine the state of various bits
1043  * to see what needs to be done.
1044  * Possible results:
1045  *    return some read request which now have data
1046  *    return some write requests which are safely on disc
1047  *    schedule a read on some buffers
1048  *    schedule a write of some buffers
1049  *    return confirmation of parity correctness
1050  *
1051  * Parity calculations are done inside the stripe lock
1052  * buffers are taken off read_list or write_list, and bh_cache buffers
1053  * get BH_Lock set before the stripe lock is released.
1054  *
1055  */
1056
1057 static void handle_stripe(struct stripe_head *sh)
1058 {
1059         raid5_conf_t *conf = sh->raid_conf;
1060         int disks = sh->disks;
1061         struct bio *return_bi= NULL;
1062         struct bio *bi;
1063         int i;
1064         int syncing;
1065         int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
1066         int non_overwrite = 0;
1067         int failed_num=0;
1068         struct r5dev *dev;
1069
1070         PRINTK("handling stripe %llu, cnt=%d, pd_idx=%d\n",
1071                 (unsigned long long)sh->sector, atomic_read(&sh->count),
1072                 sh->pd_idx);
1073
1074         spin_lock(&sh->lock);
1075         clear_bit(STRIPE_HANDLE, &sh->state);
1076         clear_bit(STRIPE_DELAYED, &sh->state);
1077
1078         syncing = test_bit(STRIPE_SYNCING, &sh->state);
1079         /* Now to look around and see what can be done */
1080
1081         rcu_read_lock();
1082         for (i=disks; i--; ) {
1083                 mdk_rdev_t *rdev;
1084                 dev = &sh->dev[i];
1085                 clear_bit(R5_Insync, &dev->flags);
1086
1087                 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
1088                         i, dev->flags, dev->toread, dev->towrite, dev->written);
1089                 /* maybe we can reply to a read */
1090                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
1091                         struct bio *rbi, *rbi2;
1092                         PRINTK("Return read for disc %d\n", i);
1093                         spin_lock_irq(&conf->device_lock);
1094                         rbi = dev->toread;
1095                         dev->toread = NULL;
1096                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1097                                 wake_up(&conf->wait_for_overlap);
1098                         spin_unlock_irq(&conf->device_lock);
1099                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1100                                 copy_data(0, rbi, dev->page, dev->sector);
1101                                 rbi2 = r5_next_bio(rbi, dev->sector);
1102                                 spin_lock_irq(&conf->device_lock);
1103                                 if (--rbi->bi_phys_segments == 0) {
1104                                         rbi->bi_next = return_bi;
1105                                         return_bi = rbi;
1106                                 }
1107                                 spin_unlock_irq(&conf->device_lock);
1108                                 rbi = rbi2;
1109                         }
1110                 }
1111
1112                 /* now count some things */
1113                 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
1114                 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
1115
1116
1117                 if (dev->toread) to_read++;
1118                 if (dev->towrite) {
1119                         to_write++;
1120                         if (!test_bit(R5_OVERWRITE, &dev->flags))
1121                                 non_overwrite++;
1122                 }
1123                 if (dev->written) written++;
1124                 rdev = rcu_dereference(conf->disks[i].rdev);
1125                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
1126                         /* The ReadError flag will just be confusing now */
1127                         clear_bit(R5_ReadError, &dev->flags);
1128                         clear_bit(R5_ReWrite, &dev->flags);
1129                 }
1130                 if (!rdev || !test_bit(In_sync, &rdev->flags)
1131                     || test_bit(R5_ReadError, &dev->flags)) {
1132                         failed++;
1133                         failed_num = i;
1134                 } else
1135                         set_bit(R5_Insync, &dev->flags);
1136         }
1137         rcu_read_unlock();
1138         PRINTK("locked=%d uptodate=%d to_read=%d"
1139                 " to_write=%d failed=%d failed_num=%d\n",
1140                 locked, uptodate, to_read, to_write, failed, failed_num);
1141         /* check if the array has lost two devices and, if so, some requests might
1142          * need to be failed
1143          */
1144         if (failed > 1 && to_read+to_write+written) {
1145                 for (i=disks; i--; ) {
1146                         int bitmap_end = 0;
1147
1148                         if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1149                                 mdk_rdev_t *rdev;
1150                                 rcu_read_lock();
1151                                 rdev = rcu_dereference(conf->disks[i].rdev);
1152                                 if (rdev && test_bit(In_sync, &rdev->flags))
1153                                         /* multiple read failures in one stripe */
1154                                         md_error(conf->mddev, rdev);
1155                                 rcu_read_unlock();
1156                         }
1157
1158                         spin_lock_irq(&conf->device_lock);
1159                         /* fail all writes first */
1160                         bi = sh->dev[i].towrite;
1161                         sh->dev[i].towrite = NULL;
1162                         if (bi) { to_write--; bitmap_end = 1; }
1163
1164                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1165                                 wake_up(&conf->wait_for_overlap);
1166
1167                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1168                                 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1169                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1170                                 if (--bi->bi_phys_segments == 0) {
1171                                         md_write_end(conf->mddev);
1172                                         bi->bi_next = return_bi;
1173                                         return_bi = bi;
1174                                 }
1175                                 bi = nextbi;
1176                         }
1177                         /* and fail all 'written' */
1178                         bi = sh->dev[i].written;
1179                         sh->dev[i].written = NULL;
1180                         if (bi) bitmap_end = 1;
1181                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
1182                                 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1183                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1184                                 if (--bi->bi_phys_segments == 0) {
1185                                         md_write_end(conf->mddev);
1186                                         bi->bi_next = return_bi;
1187                                         return_bi = bi;
1188                                 }
1189                                 bi = bi2;
1190                         }
1191
1192                         /* fail any reads if this device is non-operational */
1193                         if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1194                             test_bit(R5_ReadError, &sh->dev[i].flags)) {
1195                                 bi = sh->dev[i].toread;
1196                                 sh->dev[i].toread = NULL;
1197                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1198                                         wake_up(&conf->wait_for_overlap);
1199                                 if (bi) to_read--;
1200                                 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1201                                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1202                                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1203                                         if (--bi->bi_phys_segments == 0) {
1204                                                 bi->bi_next = return_bi;
1205                                                 return_bi = bi;
1206                                         }
1207                                         bi = nextbi;
1208                                 }
1209                         }
1210                         spin_unlock_irq(&conf->device_lock);
1211                         if (bitmap_end)
1212                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1213                                                 STRIPE_SECTORS, 0, 0);
1214                 }
1215         }
1216         if (failed > 1 && syncing) {
1217                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
1218                 clear_bit(STRIPE_SYNCING, &sh->state);
1219                 syncing = 0;
1220         }
1221
1222         /* might be able to return some write requests if the parity block
1223          * is safe, or on a failed drive
1224          */
1225         dev = &sh->dev[sh->pd_idx];
1226         if ( written &&
1227              ( (test_bit(R5_Insync, &dev->flags) && !test_bit(R5_LOCKED, &dev->flags) &&
1228                 test_bit(R5_UPTODATE, &dev->flags))
1229                || (failed == 1 && failed_num == sh->pd_idx))
1230             ) {
1231             /* any written block on an uptodate or failed drive can be returned.
1232              * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
1233              * never LOCKED, so we don't need to test 'failed' directly.
1234              */
1235             for (i=disks; i--; )
1236                 if (sh->dev[i].written) {
1237                     dev = &sh->dev[i];
1238                     if (!test_bit(R5_LOCKED, &dev->flags) &&
1239                          test_bit(R5_UPTODATE, &dev->flags) ) {
1240                         /* We can return any write requests */
1241                             struct bio *wbi, *wbi2;
1242                             int bitmap_end = 0;
1243                             PRINTK("Return write for disc %d\n", i);
1244                             spin_lock_irq(&conf->device_lock);
1245                             wbi = dev->written;
1246                             dev->written = NULL;
1247                             while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1248                                     wbi2 = r5_next_bio(wbi, dev->sector);
1249                                     if (--wbi->bi_phys_segments == 0) {
1250                                             md_write_end(conf->mddev);
1251                                             wbi->bi_next = return_bi;
1252                                             return_bi = wbi;
1253                                     }
1254                                     wbi = wbi2;
1255                             }
1256                             if (dev->towrite == NULL)
1257                                     bitmap_end = 1;
1258                             spin_unlock_irq(&conf->device_lock);
1259                             if (bitmap_end)
1260                                     bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1261                                                     STRIPE_SECTORS,
1262                                                     !test_bit(STRIPE_DEGRADED, &sh->state), 0);
1263                     }
1264                 }
1265         }
1266
1267         /* Now we might consider reading some blocks, either to check/generate
1268          * parity, or to satisfy requests
1269          * or to load a block that is being partially written.
1270          */
1271         if (to_read || non_overwrite || (syncing && (uptodate < disks))) {
1272                 for (i=disks; i--;) {
1273                         dev = &sh->dev[i];
1274                         if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1275                             (dev->toread ||
1276                              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1277                              syncing ||
1278                              (failed && (sh->dev[failed_num].toread ||
1279                                          (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags))))
1280                                     )
1281                                 ) {
1282                                 /* we would like to get this block, possibly
1283                                  * by computing it, but we might not be able to
1284                                  */
1285                                 if (uptodate == disks-1) {
1286                                         PRINTK("Computing block %d\n", i);
1287                                         compute_block(sh, i);
1288                                         uptodate++;
1289                                 } else if (test_bit(R5_Insync, &dev->flags)) {
1290                                         set_bit(R5_LOCKED, &dev->flags);
1291                                         set_bit(R5_Wantread, &dev->flags);
1292 #if 0
1293                                         /* if I am just reading this block and we don't have
1294                                            a failed drive, or any pending writes then sidestep the cache */
1295                                         if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
1296                                             ! syncing && !failed && !to_write) {
1297                                                 sh->bh_cache[i]->b_page =  sh->bh_read[i]->b_page;
1298                                                 sh->bh_cache[i]->b_data =  sh->bh_read[i]->b_data;
1299                                         }
1300 #endif
1301                                         locked++;
1302                                         PRINTK("Reading block %d (sync=%d)\n",
1303                                                 i, syncing);
1304                                 }
1305                         }
1306                 }
1307                 set_bit(STRIPE_HANDLE, &sh->state);
1308         }
1309
1310         /* now to consider writing and what else, if anything should be read */
1311         if (to_write) {
1312                 int rmw=0, rcw=0;
1313                 for (i=disks ; i--;) {
1314                         /* would I have to read this buffer for read_modify_write */
1315                         dev = &sh->dev[i];
1316                         if ((dev->towrite || i == sh->pd_idx) &&
1317                             (!test_bit(R5_LOCKED, &dev->flags)
1318 #if 0
1319 || sh->bh_page[i]!=bh->b_page
1320 #endif
1321                                     ) &&
1322                             !test_bit(R5_UPTODATE, &dev->flags)) {
1323                                 if (test_bit(R5_Insync, &dev->flags)
1324 /*                                  && !(!mddev->insync && i == sh->pd_idx) */
1325                                         )
1326                                         rmw++;
1327                                 else rmw += 2*disks;  /* cannot read it */
1328                         }
1329                         /* Would I have to read this buffer for reconstruct_write */
1330                         if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1331                             (!test_bit(R5_LOCKED, &dev->flags)
1332 #if 0
1333 || sh->bh_page[i] != bh->b_page
1334 #endif
1335                                     ) &&
1336                             !test_bit(R5_UPTODATE, &dev->flags)) {
1337                                 if (test_bit(R5_Insync, &dev->flags)) rcw++;
1338                                 else rcw += 2*disks;
1339                         }
1340                 }
1341                 PRINTK("for sector %llu, rmw=%d rcw=%d\n",
1342                         (unsigned long long)sh->sector, rmw, rcw);
1343                 set_bit(STRIPE_HANDLE, &sh->state);
1344                 if (rmw < rcw && rmw > 0)
1345                         /* prefer read-modify-write, but need to get some data */
1346                         for (i=disks; i--;) {
1347                                 dev = &sh->dev[i];
1348                                 if ((dev->towrite || i == sh->pd_idx) &&
1349                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1350                                     test_bit(R5_Insync, &dev->flags)) {
1351                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1352                                         {
1353                                                 PRINTK("Read_old block %d for r-m-w\n", i);
1354                                                 set_bit(R5_LOCKED, &dev->flags);
1355                                                 set_bit(R5_Wantread, &dev->flags);
1356                                                 locked++;
1357                                         } else {
1358                                                 set_bit(STRIPE_DELAYED, &sh->state);
1359                                                 set_bit(STRIPE_HANDLE, &sh->state);
1360                                         }
1361                                 }
1362                         }
1363                 if (rcw <= rmw && rcw > 0)
1364                         /* want reconstruct write, but need to get some data */
1365                         for (i=disks; i--;) {
1366                                 dev = &sh->dev[i];
1367                                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1368                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1369                                     test_bit(R5_Insync, &dev->flags)) {
1370                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1371                                         {
1372                                                 PRINTK("Read_old block %d for Reconstruct\n", i);
1373                                                 set_bit(R5_LOCKED, &dev->flags);
1374                                                 set_bit(R5_Wantread, &dev->flags);
1375                                                 locked++;
1376                                         } else {
1377                                                 set_bit(STRIPE_DELAYED, &sh->state);
1378                                                 set_bit(STRIPE_HANDLE, &sh->state);
1379                                         }
1380                                 }
1381                         }
1382                 /* now if nothing is locked, and if we have enough data, we can start a write request */
1383                 if (locked == 0 && (rcw == 0 ||rmw == 0) &&
1384                     !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
1385                         PRINTK("Computing parity...\n");
1386                         compute_parity(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
1387                         /* now every locked buffer is ready to be written */
1388                         for (i=disks; i--;)
1389                                 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
1390                                         PRINTK("Writing block %d\n", i);
1391                                         locked++;
1392                                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
1393                                         if (!test_bit(R5_Insync, &sh->dev[i].flags)
1394                                             || (i==sh->pd_idx && failed == 0))
1395                                                 set_bit(STRIPE_INSYNC, &sh->state);
1396                                 }
1397                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
1398                                 atomic_dec(&conf->preread_active_stripes);
1399                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
1400                                         md_wakeup_thread(conf->mddev->thread);
1401                         }
1402                 }
1403         }
1404
1405         /* maybe we need to check and possibly fix the parity for this stripe
1406          * Any reads will already have been scheduled, so we just see if enough data
1407          * is available
1408          */
1409         if (syncing && locked == 0 &&
1410             !test_bit(STRIPE_INSYNC, &sh->state)) {
1411                 set_bit(STRIPE_HANDLE, &sh->state);
1412                 if (failed == 0) {
1413                         char *pagea;
1414                         if (uptodate != disks)
1415                                 BUG();
1416                         compute_parity(sh, CHECK_PARITY);
1417                         uptodate--;
1418                         pagea = page_address(sh->dev[sh->pd_idx].page);
1419                         if ((*(u32*)pagea) == 0 &&
1420                             !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) {
1421                                 /* parity is correct (on disc, not in buffer any more) */
1422                                 set_bit(STRIPE_INSYNC, &sh->state);
1423                         } else {
1424                                 conf->mddev->resync_mismatches += STRIPE_SECTORS;
1425                                 if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
1426                                         /* don't try to repair!! */
1427                                         set_bit(STRIPE_INSYNC, &sh->state);
1428                                 else {
1429                                         compute_block(sh, sh->pd_idx);
1430                                         uptodate++;
1431                                 }
1432                         }
1433                 }
1434                 if (!test_bit(STRIPE_INSYNC, &sh->state)) {
1435                         /* either failed parity check, or recovery is happening */
1436                         if (failed==0)
1437                                 failed_num = sh->pd_idx;
1438                         dev = &sh->dev[failed_num];
1439                         BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
1440                         BUG_ON(uptodate != disks);
1441
1442                         set_bit(R5_LOCKED, &dev->flags);
1443                         set_bit(R5_Wantwrite, &dev->flags);
1444                         clear_bit(STRIPE_DEGRADED, &sh->state);
1445                         locked++;
1446                         set_bit(STRIPE_INSYNC, &sh->state);
1447                 }
1448         }
1449         if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
1450                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
1451                 clear_bit(STRIPE_SYNCING, &sh->state);
1452         }
1453
1454         /* If the failed drive is just a ReadError, then we might need to progress
1455          * the repair/check process
1456          */
1457         if (failed == 1 && ! conf->mddev->ro &&
1458             test_bit(R5_ReadError, &sh->dev[failed_num].flags)
1459             && !test_bit(R5_LOCKED, &sh->dev[failed_num].flags)
1460             && test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)
1461                 ) {
1462                 dev = &sh->dev[failed_num];
1463                 if (!test_bit(R5_ReWrite, &dev->flags)) {
1464                         set_bit(R5_Wantwrite, &dev->flags);
1465                         set_bit(R5_ReWrite, &dev->flags);
1466                         set_bit(R5_LOCKED, &dev->flags);
1467                 } else {
1468                         /* let's read it back */
1469                         set_bit(R5_Wantread, &dev->flags);
1470                         set_bit(R5_LOCKED, &dev->flags);
1471                 }
1472         }
1473
1474         spin_unlock(&sh->lock);
1475
1476         while ((bi=return_bi)) {
1477                 int bytes = bi->bi_size;
1478
1479                 return_bi = bi->bi_next;
1480                 bi->bi_next = NULL;
1481                 bi->bi_size = 0;
1482                 bi->bi_end_io(bi, bytes, 0);
1483         }
1484         for (i=disks; i-- ;) {
1485                 int rw;
1486                 struct bio *bi;
1487                 mdk_rdev_t *rdev;
1488                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
1489                         rw = 1;
1490                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1491                         rw = 0;
1492                 else
1493                         continue;
1494
1495                 bi = &sh->dev[i].req;
1496
1497                 bi->bi_rw = rw;
1498                 if (rw)
1499                         bi->bi_end_io = raid5_end_write_request;
1500                 else
1501                         bi->bi_end_io = raid5_end_read_request;
1502
1503                 rcu_read_lock();
1504                 rdev = rcu_dereference(conf->disks[i].rdev);
1505                 if (rdev && test_bit(Faulty, &rdev->flags))
1506                         rdev = NULL;
1507                 if (rdev)
1508                         atomic_inc(&rdev->nr_pending);
1509                 rcu_read_unlock();
1510
1511                 if (rdev) {
1512                         if (syncing)
1513                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1514
1515                         bi->bi_bdev = rdev->bdev;
1516                         PRINTK("for %llu schedule op %ld on disc %d\n",
1517                                 (unsigned long long)sh->sector, bi->bi_rw, i);
1518                         atomic_inc(&sh->count);
1519                         bi->bi_sector = sh->sector + rdev->data_offset;
1520                         bi->bi_flags = 1 << BIO_UPTODATE;
1521                         bi->bi_vcnt = 1;
1522                         bi->bi_max_vecs = 1;
1523                         bi->bi_idx = 0;
1524                         bi->bi_io_vec = &sh->dev[i].vec;
1525                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1526                         bi->bi_io_vec[0].bv_offset = 0;
1527                         bi->bi_size = STRIPE_SIZE;
1528                         bi->bi_next = NULL;
1529                         if (rw == WRITE &&
1530                             test_bit(R5_ReWrite, &sh->dev[i].flags))
1531                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1532                         generic_make_request(bi);
1533                 } else {
1534                         if (rw == 1)
1535                                 set_bit(STRIPE_DEGRADED, &sh->state);
1536                         PRINTK("skip op %ld on disc %d for sector %llu\n",
1537                                 bi->bi_rw, i, (unsigned long long)sh->sector);
1538                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1539                         set_bit(STRIPE_HANDLE, &sh->state);
1540                 }
1541         }
1542 }
1543
1544 static void raid5_activate_delayed(raid5_conf_t *conf)
1545 {
1546         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
1547                 while (!list_empty(&conf->delayed_list)) {
1548                         struct list_head *l = conf->delayed_list.next;
1549                         struct stripe_head *sh;
1550                         sh = list_entry(l, struct stripe_head, lru);
1551                         list_del_init(l);
1552                         clear_bit(STRIPE_DELAYED, &sh->state);
1553                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1554                                 atomic_inc(&conf->preread_active_stripes);
1555                         list_add_tail(&sh->lru, &conf->handle_list);
1556                 }
1557         }
1558 }
1559
1560 static void activate_bit_delay(raid5_conf_t *conf)
1561 {
1562         /* device_lock is held */
1563         struct list_head head;
1564         list_add(&head, &conf->bitmap_list);
1565         list_del_init(&conf->bitmap_list);
1566         while (!list_empty(&head)) {
1567                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
1568                 list_del_init(&sh->lru);
1569                 atomic_inc(&sh->count);
1570                 __release_stripe(conf, sh);
1571         }
1572 }
1573
1574 static void unplug_slaves(mddev_t *mddev)
1575 {
1576         raid5_conf_t *conf = mddev_to_conf(mddev);
1577         int i;
1578
1579         rcu_read_lock();
1580         for (i=0; i<mddev->raid_disks; i++) {
1581                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
1582                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
1583                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
1584
1585                         atomic_inc(&rdev->nr_pending);
1586                         rcu_read_unlock();
1587
1588                         if (r_queue->unplug_fn)
1589                                 r_queue->unplug_fn(r_queue);
1590
1591                         rdev_dec_pending(rdev, mddev);
1592                         rcu_read_lock();
1593                 }
1594         }
1595         rcu_read_unlock();
1596 }
1597
1598 static void raid5_unplug_device(request_queue_t *q)
1599 {
1600         mddev_t *mddev = q->queuedata;
1601         raid5_conf_t *conf = mddev_to_conf(mddev);
1602         unsigned long flags;
1603
1604         spin_lock_irqsave(&conf->device_lock, flags);
1605
1606         if (blk_remove_plug(q)) {
1607                 conf->seq_flush++;
1608                 raid5_activate_delayed(conf);
1609         }
1610         md_wakeup_thread(mddev->thread);
1611
1612         spin_unlock_irqrestore(&conf->device_lock, flags);
1613
1614         unplug_slaves(mddev);
1615 }
1616
1617 static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk,
1618                              sector_t *error_sector)
1619 {
1620         mddev_t *mddev = q->queuedata;
1621         raid5_conf_t *conf = mddev_to_conf(mddev);
1622         int i, ret = 0;
1623
1624         rcu_read_lock();
1625         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
1626                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
1627                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
1628                         struct block_device *bdev = rdev->bdev;
1629                         request_queue_t *r_queue = bdev_get_queue(bdev);
1630
1631                         if (!r_queue->issue_flush_fn)
1632                                 ret = -EOPNOTSUPP;
1633                         else {
1634                                 atomic_inc(&rdev->nr_pending);
1635                                 rcu_read_unlock();
1636                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
1637                                                               error_sector);
1638                                 rdev_dec_pending(rdev, mddev);
1639                                 rcu_read_lock();
1640                         }
1641                 }
1642         }
1643         rcu_read_unlock();
1644         return ret;
1645 }
1646
1647 static inline void raid5_plug_device(raid5_conf_t *conf)
1648 {
1649         spin_lock_irq(&conf->device_lock);
1650         blk_plug_device(conf->mddev->queue);
1651         spin_unlock_irq(&conf->device_lock);
1652 }
1653
1654 static int make_request(request_queue_t *q, struct bio * bi)
1655 {
1656         mddev_t *mddev = q->queuedata;
1657         raid5_conf_t *conf = mddev_to_conf(mddev);
1658         unsigned int dd_idx, pd_idx;
1659         sector_t new_sector;
1660         sector_t logical_sector, last_sector;
1661         struct stripe_head *sh;
1662         const int rw = bio_data_dir(bi);
1663
1664         if (unlikely(bio_barrier(bi))) {
1665                 bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
1666                 return 0;
1667         }
1668
1669         md_write_start(mddev, bi);
1670
1671         disk_stat_inc(mddev->gendisk, ios[rw]);
1672         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
1673
1674         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
1675         last_sector = bi->bi_sector + (bi->bi_size>>9);
1676         bi->bi_next = NULL;
1677         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
1678
1679         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
1680                 DEFINE_WAIT(w);
1681                 int disks;
1682
1683         retry:
1684                 if (likely(conf->expand_progress == MaxSector))
1685                         disks = conf->raid_disks;
1686                 else {
1687                         spin_lock_irq(&conf->device_lock);
1688                         disks = conf->raid_disks;
1689                         if (logical_sector >= conf->expand_progress)
1690                                 disks = conf->previous_raid_disks;
1691                         spin_unlock_irq(&conf->device_lock);
1692                 }
1693                 new_sector = raid5_compute_sector(logical_sector, disks, disks - 1,
1694                                                   &dd_idx, &pd_idx, conf);
1695                 PRINTK("raid5: make_request, sector %llu logical %llu\n",
1696                         (unsigned long long)new_sector,
1697                         (unsigned long long)logical_sector);
1698
1699                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
1700                 sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
1701                 if (sh) {
1702                         if (unlikely(conf->expand_progress != MaxSector)) {
1703                                 /* expansion might have moved on while waiting for a
1704                                  * stripe, so we much do the range check again.
1705                                  */
1706                                 int must_retry = 0;
1707                                 spin_lock_irq(&conf->device_lock);
1708                                 if (logical_sector <  conf->expand_progress &&
1709                                     disks == conf->previous_raid_disks)
1710                                         /* mismatch, need to try again */
1711                                         must_retry = 1;
1712                                 spin_unlock_irq(&conf->device_lock);
1713                                 if (must_retry) {
1714                                         release_stripe(sh);
1715                                         goto retry;
1716                                 }
1717                         }
1718
1719                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
1720                             !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
1721                                 /* Stripe is busy expanding or
1722                                  * add failed due to overlap.  Flush everything
1723                                  * and wait a while
1724                                  */
1725                                 raid5_unplug_device(mddev->queue);
1726                                 release_stripe(sh);
1727                                 schedule();
1728                                 goto retry;
1729                         }
1730                         finish_wait(&conf->wait_for_overlap, &w);
1731                         raid5_plug_device(conf);
1732                         handle_stripe(sh);
1733                         release_stripe(sh);
1734                 } else {
1735                         /* cannot get stripe for read-ahead, just give-up */
1736                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1737                         finish_wait(&conf->wait_for_overlap, &w);
1738                         break;
1739                 }
1740
1741         }
1742         spin_lock_irq(&conf->device_lock);
1743         if (--bi->bi_phys_segments == 0) {
1744                 int bytes = bi->bi_size;
1745
1746                 if ( bio_data_dir(bi) == WRITE )
1747                         md_write_end(mddev);
1748                 bi->bi_size = 0;
1749                 bi->bi_end_io(bi, bytes, 0);
1750         }
1751         spin_unlock_irq(&conf->device_lock);
1752         return 0;
1753 }
1754
1755 /* FIXME go_faster isn't used */
1756 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1757 {
1758         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1759         struct stripe_head *sh;
1760         int sectors_per_chunk = conf->chunk_size >> 9;
1761         sector_t x;
1762         unsigned long stripe;
1763         int chunk_offset;
1764         int dd_idx, pd_idx;
1765         sector_t first_sector;
1766         int raid_disks = conf->raid_disks;
1767         int data_disks = raid_disks-1;
1768         sector_t max_sector = mddev->size << 1;
1769         int sync_blocks;
1770
1771         if (sector_nr >= max_sector) {
1772                 /* just being told to finish up .. nothing much to do */
1773                 unplug_slaves(mddev);
1774
1775                 if (mddev->curr_resync < max_sector) /* aborted */
1776                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1777                                         &sync_blocks, 1);
1778                 else /* compelted sync */
1779                         conf->fullsync = 0;
1780                 bitmap_close_sync(mddev->bitmap);
1781
1782                 return 0;
1783         }
1784         /* if there is 1 or more failed drives and we are trying
1785          * to resync, then assert that we are finished, because there is
1786          * nothing we can do.
1787          */
1788         if (mddev->degraded >= 1 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1789                 sector_t rv = (mddev->size << 1) - sector_nr;
1790                 *skipped = 1;
1791                 return rv;
1792         }
1793         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
1794             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
1795             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
1796                 /* we can skip this block, and probably more */
1797                 sync_blocks /= STRIPE_SECTORS;
1798                 *skipped = 1;
1799                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
1800         }
1801
1802         x = sector_nr;
1803         chunk_offset = sector_div(x, sectors_per_chunk);
1804         stripe = x;
1805         BUG_ON(x != stripe);
1806
1807         first_sector = raid5_compute_sector((sector_t)stripe*data_disks*sectors_per_chunk
1808                 + chunk_offset, raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1809         sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
1810         if (sh == NULL) {
1811                 sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
1812                 /* make sure we don't swamp the stripe cache if someone else
1813                  * is trying to get access
1814                  */
1815                 schedule_timeout_uninterruptible(1);
1816         }
1817         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 0);
1818         spin_lock(&sh->lock);
1819         set_bit(STRIPE_SYNCING, &sh->state);
1820         clear_bit(STRIPE_INSYNC, &sh->state);
1821         spin_unlock(&sh->lock);
1822
1823         handle_stripe(sh);
1824         release_stripe(sh);
1825
1826         return STRIPE_SECTORS;
1827 }
1828
1829 /*
1830  * This is our raid5 kernel thread.
1831  *
1832  * We scan the hash table for stripes which can be handled now.
1833  * During the scan, completed stripes are saved for us by the interrupt
1834  * handler, so that they will not have to wait for our next wakeup.
1835  */
1836 static void raid5d (mddev_t *mddev)
1837 {
1838         struct stripe_head *sh;
1839         raid5_conf_t *conf = mddev_to_conf(mddev);
1840         int handled;
1841
1842         PRINTK("+++ raid5d active\n");
1843
1844         md_check_recovery(mddev);
1845
1846         handled = 0;
1847         spin_lock_irq(&conf->device_lock);
1848         while (1) {
1849                 struct list_head *first;
1850
1851                 if (conf->seq_flush - conf->seq_write > 0) {
1852                         int seq = conf->seq_flush;
1853                         spin_unlock_irq(&conf->device_lock);
1854                         bitmap_unplug(mddev->bitmap);
1855                         spin_lock_irq(&conf->device_lock);
1856                         conf->seq_write = seq;
1857                         activate_bit_delay(conf);
1858                 }
1859
1860                 if (list_empty(&conf->handle_list) &&
1861                     atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
1862                     !blk_queue_plugged(mddev->queue) &&
1863                     !list_empty(&conf->delayed_list))
1864                         raid5_activate_delayed(conf);
1865
1866                 if (list_empty(&conf->handle_list))
1867                         break;
1868
1869                 first = conf->handle_list.next;
1870                 sh = list_entry(first, struct stripe_head, lru);
1871
1872                 list_del_init(first);
1873                 atomic_inc(&sh->count);
1874                 if (atomic_read(&sh->count)!= 1)
1875                         BUG();
1876                 spin_unlock_irq(&conf->device_lock);
1877
1878                 handled++;
1879                 handle_stripe(sh);
1880                 release_stripe(sh);
1881
1882                 spin_lock_irq(&conf->device_lock);
1883         }
1884         PRINTK("%d stripes handled\n", handled);
1885
1886         spin_unlock_irq(&conf->device_lock);
1887
1888         unplug_slaves(mddev);
1889
1890         PRINTK("--- raid5d inactive\n");
1891 }
1892
1893 static ssize_t
1894 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
1895 {
1896         raid5_conf_t *conf = mddev_to_conf(mddev);
1897         if (conf)
1898                 return sprintf(page, "%d\n", conf->max_nr_stripes);
1899         else
1900                 return 0;
1901 }
1902
1903 static ssize_t
1904 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
1905 {
1906         raid5_conf_t *conf = mddev_to_conf(mddev);
1907         char *end;
1908         int new;
1909         if (len >= PAGE_SIZE)
1910                 return -EINVAL;
1911         if (!conf)
1912                 return -ENODEV;
1913
1914         new = simple_strtoul(page, &end, 10);
1915         if (!*page || (*end && *end != '\n') )
1916                 return -EINVAL;
1917         if (new <= 16 || new > 32768)
1918                 return -EINVAL;
1919         while (new < conf->max_nr_stripes) {
1920                 if (drop_one_stripe(conf))
1921                         conf->max_nr_stripes--;
1922                 else
1923                         break;
1924         }
1925         while (new > conf->max_nr_stripes) {
1926                 if (grow_one_stripe(conf))
1927                         conf->max_nr_stripes++;
1928                 else break;
1929         }
1930         return len;
1931 }
1932
1933 static struct md_sysfs_entry
1934 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
1935                                 raid5_show_stripe_cache_size,
1936                                 raid5_store_stripe_cache_size);
1937
1938 static ssize_t
1939 stripe_cache_active_show(mddev_t *mddev, char *page)
1940 {
1941         raid5_conf_t *conf = mddev_to_conf(mddev);
1942         if (conf)
1943                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
1944         else
1945                 return 0;
1946 }
1947
1948 static struct md_sysfs_entry
1949 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
1950
1951 static struct attribute *raid5_attrs[] =  {
1952         &raid5_stripecache_size.attr,
1953         &raid5_stripecache_active.attr,
1954         NULL,
1955 };
1956 static struct attribute_group raid5_attrs_group = {
1957         .name = NULL,
1958         .attrs = raid5_attrs,
1959 };
1960
1961 static int run(mddev_t *mddev)
1962 {
1963         raid5_conf_t *conf;
1964         int raid_disk, memory;
1965         mdk_rdev_t *rdev;
1966         struct disk_info *disk;
1967         struct list_head *tmp;
1968
1969         if (mddev->level != 5 && mddev->level != 4) {
1970                 printk(KERN_ERR "raid5: %s: raid level not set to 4/5 (%d)\n",
1971                        mdname(mddev), mddev->level);
1972                 return -EIO;
1973         }
1974
1975         mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
1976         if ((conf = mddev->private) == NULL)
1977                 goto abort;
1978         conf->disks = kzalloc(mddev->raid_disks * sizeof(struct disk_info),
1979                               GFP_KERNEL);
1980         if (!conf->disks)
1981                 goto abort;
1982
1983         conf->mddev = mddev;
1984
1985         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
1986                 goto abort;
1987
1988         spin_lock_init(&conf->device_lock);
1989         init_waitqueue_head(&conf->wait_for_stripe);
1990         init_waitqueue_head(&conf->wait_for_overlap);
1991         INIT_LIST_HEAD(&conf->handle_list);
1992         INIT_LIST_HEAD(&conf->delayed_list);
1993         INIT_LIST_HEAD(&conf->bitmap_list);
1994         INIT_LIST_HEAD(&conf->inactive_list);
1995         atomic_set(&conf->active_stripes, 0);
1996         atomic_set(&conf->preread_active_stripes, 0);
1997
1998         PRINTK("raid5: run(%s) called.\n", mdname(mddev));
1999
2000         ITERATE_RDEV(mddev,rdev,tmp) {
2001                 raid_disk = rdev->raid_disk;
2002                 if (raid_disk >= mddev->raid_disks
2003                     || raid_disk < 0)
2004                         continue;
2005                 disk = conf->disks + raid_disk;
2006
2007                 disk->rdev = rdev;
2008
2009                 if (test_bit(In_sync, &rdev->flags)) {
2010                         char b[BDEVNAME_SIZE];
2011                         printk(KERN_INFO "raid5: device %s operational as raid"
2012                                 " disk %d\n", bdevname(rdev->bdev,b),
2013                                 raid_disk);
2014                         conf->working_disks++;
2015                 }
2016         }
2017
2018         conf->raid_disks = mddev->raid_disks;
2019         /*
2020          * 0 for a fully functional array, 1 for a degraded array.
2021          */
2022         mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks;
2023         conf->mddev = mddev;
2024         conf->chunk_size = mddev->chunk_size;
2025         conf->level = mddev->level;
2026         conf->algorithm = mddev->layout;
2027         conf->max_nr_stripes = NR_STRIPES;
2028         conf->expand_progress = MaxSector;
2029
2030         /* device size must be a multiple of chunk size */
2031         mddev->size &= ~(mddev->chunk_size/1024 -1);
2032         mddev->resync_max_sectors = mddev->size << 1;
2033
2034         if (!conf->chunk_size || conf->chunk_size % 4) {
2035                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
2036                         conf->chunk_size, mdname(mddev));
2037                 goto abort;
2038         }
2039         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
2040                 printk(KERN_ERR
2041                         "raid5: unsupported parity algorithm %d for %s\n",
2042                         conf->algorithm, mdname(mddev));
2043                 goto abort;
2044         }
2045         if (mddev->degraded > 1) {
2046                 printk(KERN_ERR "raid5: not enough operational devices for %s"
2047                         " (%d/%d failed)\n",
2048                         mdname(mddev), conf->failed_disks, conf->raid_disks);
2049                 goto abort;
2050         }
2051
2052         if (mddev->degraded == 1 &&
2053             mddev->recovery_cp != MaxSector) {
2054                 if (mddev->ok_start_degraded)
2055                         printk(KERN_WARNING
2056                                "raid5: starting dirty degraded array: %s"
2057                                "- data corruption possible.\n",
2058                                mdname(mddev));
2059                 else {
2060                         printk(KERN_ERR
2061                                "raid5: cannot start dirty degraded array for %s\n",
2062                                mdname(mddev));
2063                         goto abort;
2064                 }
2065         }
2066
2067         {
2068                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
2069                 if (!mddev->thread) {
2070                         printk(KERN_ERR
2071                                 "raid5: couldn't allocate thread for %s\n",
2072                                 mdname(mddev));
2073                         goto abort;
2074                 }
2075         }
2076         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
2077                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
2078         if (grow_stripes(conf, conf->max_nr_stripes)) {
2079                 printk(KERN_ERR
2080                         "raid5: couldn't allocate %dkB for buffers\n", memory);
2081                 shrink_stripes(conf);
2082                 md_unregister_thread(mddev->thread);
2083                 goto abort;
2084         } else
2085                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
2086                         memory, mdname(mddev));
2087
2088         if (mddev->degraded == 0)
2089                 printk("raid5: raid level %d set %s active with %d out of %d"
2090                         " devices, algorithm %d\n", conf->level, mdname(mddev),
2091                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
2092                         conf->algorithm);
2093         else
2094                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
2095                         " out of %d devices, algorithm %d\n", conf->level,
2096                         mdname(mddev), mddev->raid_disks - mddev->degraded,
2097                         mddev->raid_disks, conf->algorithm);
2098
2099         print_raid5_conf(conf);
2100
2101         /* read-ahead size must cover two whole stripes, which is
2102          * 2 * (n-1) * chunksize where 'n' is the number of raid devices
2103          */
2104         {
2105                 int stripe = (mddev->raid_disks-1) * mddev->chunk_size
2106                         / PAGE_SIZE;
2107                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
2108                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
2109         }
2110
2111         /* Ok, everything is just fine now */
2112         sysfs_create_group(&mddev->kobj, &raid5_attrs_group);
2113
2114         mddev->queue->unplug_fn = raid5_unplug_device;
2115         mddev->queue->issue_flush_fn = raid5_issue_flush;
2116
2117         mddev->array_size =  mddev->size * (mddev->raid_disks - 1);
2118         return 0;
2119 abort:
2120         if (conf) {
2121                 print_raid5_conf(conf);
2122                 kfree(conf->disks);
2123                 kfree(conf->stripe_hashtbl);
2124                 kfree(conf);
2125         }
2126         mddev->private = NULL;
2127         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
2128         return -EIO;
2129 }
2130
2131
2132
2133 static int stop(mddev_t *mddev)
2134 {
2135         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
2136
2137         md_unregister_thread(mddev->thread);
2138         mddev->thread = NULL;
2139         shrink_stripes(conf);
2140         kfree(conf->stripe_hashtbl);
2141         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2142         sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
2143         kfree(conf->disks);
2144         kfree(conf);
2145         mddev->private = NULL;
2146         return 0;
2147 }
2148
2149 #if RAID5_DEBUG
2150 static void print_sh (struct stripe_head *sh)
2151 {
2152         int i;
2153
2154         printk("sh %llu, pd_idx %d, state %ld.\n",
2155                 (unsigned long long)sh->sector, sh->pd_idx, sh->state);
2156         printk("sh %llu,  count %d.\n",
2157                 (unsigned long long)sh->sector, atomic_read(&sh->count));
2158         printk("sh %llu, ", (unsigned long long)sh->sector);
2159         for (i = 0; i < sh->disks; i++) {
2160                 printk("(cache%d: %p %ld) ",
2161                         i, sh->dev[i].page, sh->dev[i].flags);
2162         }
2163         printk("\n");
2164 }
2165
2166 static void printall (raid5_conf_t *conf)
2167 {
2168         struct stripe_head *sh;
2169         struct hlist_node *hn;
2170         int i;
2171
2172         spin_lock_irq(&conf->device_lock);
2173         for (i = 0; i < NR_HASH; i++) {
2174                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
2175                         if (sh->raid_conf != conf)
2176                                 continue;
2177                         print_sh(sh);
2178                 }
2179         }
2180         spin_unlock_irq(&conf->device_lock);
2181 }
2182 #endif
2183
2184 static void status (struct seq_file *seq, mddev_t *mddev)
2185 {
2186         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
2187         int i;
2188
2189         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
2190         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->working_disks);
2191         for (i = 0; i < conf->raid_disks; i++)
2192                 seq_printf (seq, "%s",
2193                                conf->disks[i].rdev &&
2194                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
2195         seq_printf (seq, "]");
2196 #if RAID5_DEBUG
2197 #define D(x) \
2198         seq_printf (seq, "<"#x":%d>", atomic_read(&conf->x))
2199         printall(conf);
2200 #endif
2201 }
2202
2203 static void print_raid5_conf (raid5_conf_t *conf)
2204 {
2205         int i;
2206         struct disk_info *tmp;
2207
2208         printk("RAID5 conf printout:\n");
2209         if (!conf) {
2210                 printk("(conf==NULL)\n");
2211                 return;
2212         }
2213         printk(" --- rd:%d wd:%d fd:%d\n", conf->raid_disks,
2214                  conf->working_disks, conf->failed_disks);
2215
2216         for (i = 0; i < conf->raid_disks; i++) {
2217                 char b[BDEVNAME_SIZE];
2218                 tmp = conf->disks + i;
2219                 if (tmp->rdev)
2220                 printk(" disk %d, o:%d, dev:%s\n",
2221                         i, !test_bit(Faulty, &tmp->rdev->flags),
2222                         bdevname(tmp->rdev->bdev,b));
2223         }
2224 }
2225
2226 static int raid5_spare_active(mddev_t *mddev)
2227 {
2228         int i;
2229         raid5_conf_t *conf = mddev->private;
2230         struct disk_info *tmp;
2231
2232         for (i = 0; i < conf->raid_disks; i++) {
2233                 tmp = conf->disks + i;
2234                 if (tmp->rdev
2235                     && !test_bit(Faulty, &tmp->rdev->flags)
2236                     && !test_bit(In_sync, &tmp->rdev->flags)) {
2237                         mddev->degraded--;
2238                         conf->failed_disks--;
2239                         conf->working_disks++;
2240                         set_bit(In_sync, &tmp->rdev->flags);
2241                 }
2242         }
2243         print_raid5_conf(conf);
2244         return 0;
2245 }
2246
2247 static int raid5_remove_disk(mddev_t *mddev, int number)
2248 {
2249         raid5_conf_t *conf = mddev->private;
2250         int err = 0;
2251         mdk_rdev_t *rdev;
2252         struct disk_info *p = conf->disks + number;
2253
2254         print_raid5_conf(conf);
2255         rdev = p->rdev;
2256         if (rdev) {
2257                 if (test_bit(In_sync, &rdev->flags) ||
2258                     atomic_read(&rdev->nr_pending)) {
2259                         err = -EBUSY;
2260                         goto abort;
2261                 }
2262                 p->rdev = NULL;
2263                 synchronize_rcu();
2264                 if (atomic_read(&rdev->nr_pending)) {
2265                         /* lost the race, try later */
2266                         err = -EBUSY;
2267                         p->rdev = rdev;
2268                 }
2269         }
2270 abort:
2271
2272         print_raid5_conf(conf);
2273         return err;
2274 }
2275
2276 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
2277 {
2278         raid5_conf_t *conf = mddev->private;
2279         int found = 0;
2280         int disk;
2281         struct disk_info *p;
2282
2283         if (mddev->degraded > 1)
2284                 /* no point adding a device */
2285                 return 0;
2286
2287         /*
2288          * find the disk ...
2289          */
2290         for (disk=0; disk < mddev->raid_disks; disk++)
2291                 if ((p=conf->disks + disk)->rdev == NULL) {
2292                         clear_bit(In_sync, &rdev->flags);
2293                         rdev->raid_disk = disk;
2294                         found = 1;
2295                         if (rdev->saved_raid_disk != disk)
2296                                 conf->fullsync = 1;
2297                         rcu_assign_pointer(p->rdev, rdev);
2298                         break;
2299                 }
2300         print_raid5_conf(conf);
2301         return found;
2302 }
2303
2304 static int raid5_resize(mddev_t *mddev, sector_t sectors)
2305 {
2306         /* no resync is happening, and there is enough space
2307          * on all devices, so we can resize.
2308          * We need to make sure resync covers any new space.
2309          * If the array is shrinking we should possibly wait until
2310          * any io in the removed space completes, but it hardly seems
2311          * worth it.
2312          */
2313         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
2314         mddev->array_size = (sectors * (mddev->raid_disks-1))>>1;
2315         set_capacity(mddev->gendisk, mddev->array_size << 1);
2316         mddev->changed = 1;
2317         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
2318                 mddev->recovery_cp = mddev->size << 1;
2319                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
2320         }
2321         mddev->size = sectors /2;
2322         mddev->resync_max_sectors = sectors;
2323         return 0;
2324 }
2325
2326 static void raid5_quiesce(mddev_t *mddev, int state)
2327 {
2328         raid5_conf_t *conf = mddev_to_conf(mddev);
2329
2330         switch(state) {
2331         case 1: /* stop all writes */
2332                 spin_lock_irq(&conf->device_lock);
2333                 conf->quiesce = 1;
2334                 wait_event_lock_irq(conf->wait_for_stripe,
2335                                     atomic_read(&conf->active_stripes) == 0,
2336                                     conf->device_lock, /* nothing */);
2337                 spin_unlock_irq(&conf->device_lock);
2338                 break;
2339
2340         case 0: /* re-enable writes */
2341                 spin_lock_irq(&conf->device_lock);
2342                 conf->quiesce = 0;
2343                 wake_up(&conf->wait_for_stripe);
2344                 spin_unlock_irq(&conf->device_lock);
2345                 break;
2346         }
2347 }
2348
2349 static struct mdk_personality raid5_personality =
2350 {
2351         .name           = "raid5",
2352         .level          = 5,
2353         .owner          = THIS_MODULE,
2354         .make_request   = make_request,
2355         .run            = run,
2356         .stop           = stop,
2357         .status         = status,
2358         .error_handler  = error,
2359         .hot_add_disk   = raid5_add_disk,
2360         .hot_remove_disk= raid5_remove_disk,
2361         .spare_active   = raid5_spare_active,
2362         .sync_request   = sync_request,
2363         .resize         = raid5_resize,
2364         .quiesce        = raid5_quiesce,
2365 };
2366
2367 static struct mdk_personality raid4_personality =
2368 {
2369         .name           = "raid4",
2370         .level          = 4,
2371         .owner          = THIS_MODULE,
2372         .make_request   = make_request,
2373         .run            = run,
2374         .stop           = stop,
2375         .status         = status,
2376         .error_handler  = error,
2377         .hot_add_disk   = raid5_add_disk,
2378         .hot_remove_disk= raid5_remove_disk,
2379         .spare_active   = raid5_spare_active,
2380         .sync_request   = sync_request,
2381         .resize         = raid5_resize,
2382         .quiesce        = raid5_quiesce,
2383 };
2384
2385 static int __init raid5_init(void)
2386 {
2387         register_md_personality(&raid5_personality);
2388         register_md_personality(&raid4_personality);
2389         return 0;
2390 }
2391
2392 static void raid5_exit(void)
2393 {
2394         unregister_md_personality(&raid5_personality);
2395         unregister_md_personality(&raid4_personality);
2396 }
2397
2398 module_init(raid5_init);
2399 module_exit(raid5_exit);
2400 MODULE_LICENSE("GPL");
2401 MODULE_ALIAS("md-personality-4"); /* RAID5 */
2402 MODULE_ALIAS("md-raid5");
2403 MODULE_ALIAS("md-raid4");
2404 MODULE_ALIAS("md-level-5");
2405 MODULE_ALIAS("md-level-4");