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  *         Copyright (C) 2002, 2003 H. Peter Anvin
   6  *
   7  * RAID-4/5/6 management functions.
   8  * Thanks to Penguin Computing for making the RAID-6 development possible
   9  * by donating a test server!
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21
  22 #include <linux/config.h>
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/highmem.h>
  26 #include <linux/bitops.h>
  27 #include <linux/kthread.h>
  28 #include <asm/atomic.h>
  29 #include "raid6.h"
  30
  31 #include <linux/raid/bitmap.h>
  32
  33 /*
  34  * Stripe cache
  35  */
  36
  37 #define NR_STRIPES              256
  38 #define STRIPE_SIZE             PAGE_SIZE
  39 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  40 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  41 #define IO_THRESHOLD            1
  42 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  43 #define HASH_MASK               (NR_HASH - 1)
  44
  45 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
  46
  47 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
  48  * order without overlap.  There may be several bio's per stripe+device, and
  49  * a bio could span several devices.
  50  * When walking this list for a particular stripe+device, we must never proceed
  51  * beyond a bio that extends past this device, as the next bio might no longer
  52  * be valid.
  53  * This macro is used to determine the 'next' bio in the list, given the sector
  54  * of the current stripe+device
  55  */
  56 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
  57 /*
  58  * The following can be used to debug the driver
  59  */
  60 #define RAID5_DEBUG     0
  61 #define RAID5_PARANOIA  1
  62 #if RAID5_PARANOIA && defined(CONFIG_SMP)
  63 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
  64 #else
  65 # define CHECK_DEVLOCK()
  66 #endif
  67
  68 #define PRINTK(x...) ((void)(RAID5_DEBUG && printk(x)))
  69 #if RAID5_DEBUG
  70 #define inline
  71 #define __inline__
  72 #endif
  73
  74 #if !RAID6_USE_EMPTY_ZERO_PAGE
  75 /* In .bss so it's zeroed */
  76 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
  77 #endif
  78
  79 static inline int raid6_next_disk(int disk, int raid_disks)
  80 {
  81         disk++;
  82         return (disk < raid_disks) ? disk : 0;
  83 }
  84 static void print_raid5_conf (raid5_conf_t *conf);
  85
  86 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
  87 {
  88         if (atomic_dec_and_test(&sh->count)) {
  89                 BUG_ON(!list_empty(&sh->lru));
  90                 BUG_ON(atomic_read(&conf->active_stripes)==0);
  91                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
  92                         if (test_bit(STRIPE_DELAYED, &sh->state))
  93                                 list_add_tail(&sh->lru, &conf->delayed_list);
  94                         else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
  95                                  conf->seq_write == sh->bm_seq)
  96                                 list_add_tail(&sh->lru, &conf->bitmap_list);
  97                         else {
  98                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
  99                                 list_add_tail(&sh->lru, &conf->handle_list);
 100                         }
 101                         md_wakeup_thread(conf->mddev->thread);
 102                 } else {
 103                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
 104                                 atomic_dec(&conf->preread_active_stripes);
 105                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
 106                                         md_wakeup_thread(conf->mddev->thread);
 107                         }
 108                         atomic_dec(&conf->active_stripes);
 109                         if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 110                                 list_add_tail(&sh->lru, &conf->inactive_list);
 111                                 wake_up(&conf->wait_for_stripe);
 112                         }
 113                 }
 114         }
 115 }
 116 static void release_stripe(struct stripe_head *sh)
 117 {
 118         raid5_conf_t *conf = sh->raid_conf;
 119         unsigned long flags;
 120
 121         spin_lock_irqsave(&conf->device_lock, flags);
 122         __release_stripe(conf, sh);
 123         spin_unlock_irqrestore(&conf->device_lock, flags);
 124 }
 125
 126 static inline void remove_hash(struct stripe_head *sh)
 127 {
 128         PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 129
 130         hlist_del_init(&sh->hash);
 131 }
 132
 133 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
 134 {
 135         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 136
 137         PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 138
 139         CHECK_DEVLOCK();
 140         hlist_add_head(&sh->hash, hp);
 141 }
 142
 143
 144 /* find an idle stripe, make sure it is unhashed, and return it. */
 145 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
 146 {
 147         struct stripe_head *sh = NULL;
 148         struct list_head *first;
 149
 150         CHECK_DEVLOCK();
 151         if (list_empty(&conf->inactive_list))
 152                 goto out;
 153         first = conf->inactive_list.next;
 154         sh = list_entry(first, struct stripe_head, lru);
 155         list_del_init(first);
 156         remove_hash(sh);
 157         atomic_inc(&conf->active_stripes);
 158 out:
 159         return sh;
 160 }
 161
 162 static void shrink_buffers(struct stripe_head *sh, int num)
 163 {
 164         struct page *p;
 165         int i;
 166
 167         for (i=0; i<num ; i++) {
 168                 p = sh->dev[i].page;
 169                 if (!p)
 170                         continue;
 171                 sh->dev[i].page = NULL;
 172                 put_page(p);
 173         }
 174 }
 175
 176 static int grow_buffers(struct stripe_head *sh, int num)
 177 {
 178         int i;
 179
 180         for (i=0; i<num; i++) {
 181                 struct page *page;
 182
 183                 if (!(page = alloc_page(GFP_KERNEL))) {
 184                         return 1;
 185                 }
 186                 sh->dev[i].page = page;
 187         }
 188         return 0;
 189 }
 190
 191 static void raid5_build_block (struct stripe_head *sh, int i);
 192
 193 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
 194 {
 195         raid5_conf_t *conf = sh->raid_conf;
 196         int i;
 197
 198         BUG_ON(atomic_read(&sh->count) != 0);
 199         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 200
 201         CHECK_DEVLOCK();
 202         PRINTK("init_stripe called, stripe %llu\n",
 203                 (unsigned long long)sh->sector);
 204
 205         remove_hash(sh);
 206
 207         sh->sector = sector;
 208         sh->pd_idx = pd_idx;
 209         sh->state = 0;
 210
 211         sh->disks = disks;
 212
 213         for (i = sh->disks; i--; ) {
 214                 struct r5dev *dev = &sh->dev[i];
 215
 216                 if (dev->toread || dev->towrite || dev->written ||
 217                     test_bit(R5_LOCKED, &dev->flags)) {
 218                         printk("sector=%llx i=%d %p %p %p %d\n",
 219                                (unsigned long long)sh->sector, i, dev->toread,
 220                                dev->towrite, dev->written,
 221                                test_bit(R5_LOCKED, &dev->flags));
 222                         BUG();
 223                 }
 224                 dev->flags = 0;
 225                 raid5_build_block(sh, i);
 226         }
 227         insert_hash(conf, sh);
 228 }
 229
 230 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
 231 {
 232         struct stripe_head *sh;
 233         struct hlist_node *hn;
 234
 235         CHECK_DEVLOCK();
 236         PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
 237         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
 238                 if (sh->sector == sector && sh->disks == disks)
 239                         return sh;
 240         PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
 241         return NULL;
 242 }
 243
 244 static void unplug_slaves(mddev_t *mddev);
 245 static void raid5_unplug_device(request_queue_t *q);
 246
 247 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
 248                                              int pd_idx, int noblock)
 249 {
 250         struct stripe_head *sh;
 251
 252         PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
 253
 254         spin_lock_irq(&conf->device_lock);
 255
 256         do {
 257                 wait_event_lock_irq(conf->wait_for_stripe,
 258                                     conf->quiesce == 0,
 259                                     conf->device_lock, /* nothing */);
 260                 sh = __find_stripe(conf, sector, disks);
 261                 if (!sh) {
 262                         if (!conf->inactive_blocked)
 263                                 sh = get_free_stripe(conf);
 264                         if (noblock && sh == NULL)
 265                                 break;
 266                         if (!sh) {
 267                                 conf->inactive_blocked = 1;
 268                                 wait_event_lock_irq(conf->wait_for_stripe,
 269                                                     !list_empty(&conf->inactive_list) &&
 270                                                     (atomic_read(&conf->active_stripes)
 271                                                      < (conf->max_nr_stripes *3/4)
 272                                                      || !conf->inactive_blocked),
 273                                                     conf->device_lock,
 274                                                     unplug_slaves(conf->mddev)
 275                                         );
 276                                 conf->inactive_blocked = 0;
 277                         } else
 278                                 init_stripe(sh, sector, pd_idx, disks);
 279                 } else {
 280                         if (atomic_read(&sh->count)) {
 281                           BUG_ON(!list_empty(&sh->lru));
 282                         } else {
 283                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 284                                         atomic_inc(&conf->active_stripes);
 285                                 if (list_empty(&sh->lru))
 286                                         BUG();
 287                                 list_del_init(&sh->lru);
 288                         }
 289                 }
 290         } while (sh == NULL);
 291
 292         if (sh)
 293                 atomic_inc(&sh->count);
 294
 295         spin_unlock_irq(&conf->device_lock);
 296         return sh;
 297 }
 298
 299 static int grow_one_stripe(raid5_conf_t *conf)
 300 {
 301         struct stripe_head *sh;
 302         sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
 303         if (!sh)
 304                 return 0;
 305         memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
 306         sh->raid_conf = conf;
 307         spin_lock_init(&sh->lock);
 308
 309         if (grow_buffers(sh, conf->raid_disks)) {
 310                 shrink_buffers(sh, conf->raid_disks);
 311                 kmem_cache_free(conf->slab_cache, sh);
 312                 return 0;
 313         }
 314         sh->disks = conf->raid_disks;
 315         /* we just created an active stripe so... */
 316         atomic_set(&sh->count, 1);
 317         atomic_inc(&conf->active_stripes);
 318         INIT_LIST_HEAD(&sh->lru);
 319         release_stripe(sh);
 320         return 1;
 321 }
 322
 323 static int grow_stripes(raid5_conf_t *conf, int num)
 324 {
 325         kmem_cache_t *sc;
 326         int devs = conf->raid_disks;
 327
 328         sprintf(conf->cache_name[0], "raid5/%s", mdname(conf->mddev));
 329         sprintf(conf->cache_name[1], "raid5/%s-alt", mdname(conf->mddev));
 330         conf->active_name = 0;
 331         sc = kmem_cache_create(conf->cache_name[conf->active_name],
 332                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
 333                                0, 0, NULL, NULL);
 334         if (!sc)
 335                 return 1;
 336         conf->slab_cache = sc;
 337         conf->pool_size = devs;
 338         while (num--)
 339                 if (!grow_one_stripe(conf))
 340                         return 1;
 341         return 0;
 342 }
 343
 344 #ifdef CONFIG_MD_RAID5_RESHAPE
 345 static int resize_stripes(raid5_conf_t *conf, int newsize)
 346 {
 347         /* Make all the stripes able to hold 'newsize' devices.
 348          * New slots in each stripe get 'page' set to a new page.
 349          *
 350          * This happens in stages:
 351          * 1/ create a new kmem_cache and allocate the required number of
 352          *    stripe_heads.
 353          * 2/ gather all the old stripe_heads and tranfer the pages across
 354          *    to the new stripe_heads.  This will have the side effect of
 355          *    freezing the array as once all stripe_heads have been collected,
 356          *    no IO will be possible.  Old stripe heads are freed once their
 357          *    pages have been transferred over, and the old kmem_cache is
 358          *    freed when all stripes are done.
 359          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
 360          *    we simple return a failre status - no need to clean anything up.
 361          * 4/ allocate new pages for the new slots in the new stripe_heads.
 362          *    If this fails, we don't bother trying the shrink the
 363          *    stripe_heads down again, we just leave them as they are.
 364          *    As each stripe_head is processed the new one is released into
 365          *    active service.
 366          *
 367          * Once step2 is started, we cannot afford to wait for a write,
 368          * so we use GFP_NOIO allocations.
 369          */
 370         struct stripe_head *osh, *nsh;
 371         LIST_HEAD(newstripes);
 372         struct disk_info *ndisks;
 373         int err = 0;
 374         kmem_cache_t *sc;
 375         int i;
 376
 377         if (newsize <= conf->pool_size)
 378                 return 0; /* never bother to shrink */
 379
 380         /* Step 1 */
 381         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
 382                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
 383                                0, 0, NULL, NULL);
 384         if (!sc)
 385                 return -ENOMEM;
 386
 387         for (i = conf->max_nr_stripes; i; i--) {
 388                 nsh = kmem_cache_alloc(sc, GFP_KERNEL);
 389                 if (!nsh)
 390                         break;
 391
 392                 memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
 393
 394                 nsh->raid_conf = conf;
 395                 spin_lock_init(&nsh->lock);
 396
 397                 list_add(&nsh->lru, &newstripes);
 398         }
 399         if (i) {
 400                 /* didn't get enough, give up */
 401                 while (!list_empty(&newstripes)) {
 402                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
 403                         list_del(&nsh->lru);
 404                         kmem_cache_free(sc, nsh);
 405                 }
 406                 kmem_cache_destroy(sc);
 407                 return -ENOMEM;
 408         }
 409         /* Step 2 - Must use GFP_NOIO now.
 410          * OK, we have enough stripes, start collecting inactive
 411          * stripes and copying them over
 412          */
 413         list_for_each_entry(nsh, &newstripes, lru) {
 414                 spin_lock_irq(&conf->device_lock);
 415                 wait_event_lock_irq(conf->wait_for_stripe,
 416                                     !list_empty(&conf->inactive_list),
 417                                     conf->device_lock,
 418                                     unplug_slaves(conf->mddev)
 419                         );
 420                 osh = get_free_stripe(conf);
 421                 spin_unlock_irq(&conf->device_lock);
 422                 atomic_set(&nsh->count, 1);
 423                 for(i=0; i<conf->pool_size; i++)
 424                         nsh->dev[i].page = osh->dev[i].page;
 425                 for( ; i<newsize; i++)
 426                         nsh->dev[i].page = NULL;
 427                 kmem_cache_free(conf->slab_cache, osh);
 428         }
 429         kmem_cache_destroy(conf->slab_cache);
 430
 431         /* Step 3.
 432          * At this point, we are holding all the stripes so the array
 433          * is completely stalled, so now is a good time to resize
 434          * conf->disks.
 435          */
 436         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
 437         if (ndisks) {
 438                 for (i=0; i<conf->raid_disks; i++)
 439                         ndisks[i] = conf->disks[i];
 440                 kfree(conf->disks);
 441                 conf->disks = ndisks;
 442         } else
 443                 err = -ENOMEM;
 444
 445         /* Step 4, return new stripes to service */
 446         while(!list_empty(&newstripes)) {
 447                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
 448                 list_del_init(&nsh->lru);
 449                 for (i=conf->raid_disks; i < newsize; i++)
 450                         if (nsh->dev[i].page == NULL) {
 451                                 struct page *p = alloc_page(GFP_NOIO);
 452                                 nsh->dev[i].page = p;
 453                                 if (!p)
 454                                         err = -ENOMEM;
 455                         }
 456                 release_stripe(nsh);
 457         }
 458         /* critical section pass, GFP_NOIO no longer needed */
 459
 460         conf->slab_cache = sc;
 461         conf->active_name = 1-conf->active_name;
 462         conf->pool_size = newsize;
 463         return err;
 464 }
 465 #endif
 466
 467 static int drop_one_stripe(raid5_conf_t *conf)
 468 {
 469         struct stripe_head *sh;
 470
 471         spin_lock_irq(&conf->device_lock);
 472         sh = get_free_stripe(conf);
 473         spin_unlock_irq(&conf->device_lock);
 474         if (!sh)
 475                 return 0;
 476         BUG_ON(atomic_read(&sh->count));
 477         shrink_buffers(sh, conf->pool_size);
 478         kmem_cache_free(conf->slab_cache, sh);
 479         atomic_dec(&conf->active_stripes);
 480         return 1;
 481 }
 482
 483 static void shrink_stripes(raid5_conf_t *conf)
 484 {
 485         while (drop_one_stripe(conf))
 486                 ;
 487
 488         if (conf->slab_cache)
 489                 kmem_cache_destroy(conf->slab_cache);
 490         conf->slab_cache = NULL;
 491 }
 492
 493 static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done,
 494                                    int error)
 495 {
 496         struct stripe_head *sh = bi->bi_private;
 497         raid5_conf_t *conf = sh->raid_conf;
 498         int disks = sh->disks, i;
 499         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 500
 501         if (bi->bi_size)
 502                 return 1;
 503
 504         for (i=0 ; i<disks; i++)
 505                 if (bi == &sh->dev[i].req)
 506                         break;
 507
 508         PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n",
 509                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
 510                 uptodate);
 511         if (i == disks) {
 512                 BUG();
 513                 return 0;
 514         }
 515
 516         if (uptodate) {
 517 #if 0
 518                 struct bio *bio;
 519                 unsigned long flags;
 520                 spin_lock_irqsave(&conf->device_lock, flags);
 521                 /* we can return a buffer if we bypassed the cache or
 522                  * if the top buffer is not in highmem.  If there are
 523                  * multiple buffers, leave the extra work to
 524                  * handle_stripe
 525                  */
 526                 buffer = sh->bh_read[i];
 527                 if (buffer &&
 528                     (!PageHighMem(buffer->b_page)
 529                      || buffer->b_page == bh->b_page )
 530                         ) {
 531                         sh->bh_read[i] = buffer->b_reqnext;
 532                         buffer->b_reqnext = NULL;
 533                 } else
 534                         buffer = NULL;
 535                 spin_unlock_irqrestore(&conf->device_lock, flags);
 536                 if (sh->bh_page[i]==bh->b_page)
 537                         set_buffer_uptodate(bh);
 538                 if (buffer) {
 539                         if (buffer->b_page != bh->b_page)
 540                                 memcpy(buffer->b_data, bh->b_data, bh->b_size);
 541                         buffer->b_end_io(buffer, 1);
 542                 }
 543 #else
 544                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
 545 #endif
 546                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
 547                         printk(KERN_INFO "raid5: read error corrected!!\n");
 548                         clear_bit(R5_ReadError, &sh->dev[i].flags);
 549                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
 550                 }
 551                 if (atomic_read(&conf->disks[i].rdev->read_errors))
 552                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
 553         } else {
 554                 int retry = 0;
 555                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
 556                 atomic_inc(&conf->disks[i].rdev->read_errors);
 557                 if (conf->mddev->degraded)
 558                         printk(KERN_WARNING "raid5: read error not correctable.\n");
 559                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
 560                         /* Oh, no!!! */
 561                         printk(KERN_WARNING "raid5: read error NOT corrected!!\n");
 562                 else if (atomic_read(&conf->disks[i].rdev->read_errors)
 563                          > conf->max_nr_stripes)
 564                         printk(KERN_WARNING
 565                                "raid5: Too many read errors, failing device.\n");
 566                 else
 567                         retry = 1;
 568                 if (retry)
 569                         set_bit(R5_ReadError, &sh->dev[i].flags);
 570                 else {
 571                         clear_bit(R5_ReadError, &sh->dev[i].flags);
 572                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
 573                         md_error(conf->mddev, conf->disks[i].rdev);
 574                 }
 575         }
 576         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 577 #if 0
 578         /* must restore b_page before unlocking buffer... */
 579         if (sh->bh_page[i] != bh->b_page) {
 580                 bh->b_page = sh->bh_page[i];
 581                 bh->b_data = page_address(bh->b_page);
 582                 clear_buffer_uptodate(bh);
 583         }
 584 #endif
 585         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 586         set_bit(STRIPE_HANDLE, &sh->state);
 587         release_stripe(sh);
 588         return 0;
 589 }
 590
 591 static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
 592                                     int error)
 593 {
 594         struct stripe_head *sh = bi->bi_private;
 595         raid5_conf_t *conf = sh->raid_conf;
 596         int disks = sh->disks, i;
 597         unsigned long flags;
 598         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 599
 600         if (bi->bi_size)
 601                 return 1;
 602
 603         for (i=0 ; i<disks; i++)
 604                 if (bi == &sh->dev[i].req)
 605                         break;
 606
 607         PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n",
 608                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
 609                 uptodate);
 610         if (i == disks) {
 611                 BUG();
 612                 return 0;
 613         }
 614
 615         spin_lock_irqsave(&conf->device_lock, flags);
 616         if (!uptodate)
 617                 md_error(conf->mddev, conf->disks[i].rdev);
 618
 619         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 620
 621         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 622         set_bit(STRIPE_HANDLE, &sh->state);
 623         __release_stripe(conf, sh);
 624         spin_unlock_irqrestore(&conf->device_lock, flags);
 625         return 0;
 626 }
 627
 628
 629 static sector_t compute_blocknr(struct stripe_head *sh, int i);
 630
 631 static void raid5_build_block (struct stripe_head *sh, int i)
 632 {
 633         struct r5dev *dev = &sh->dev[i];
 634
 635         bio_init(&dev->req);
 636         dev->req.bi_io_vec = &dev->vec;
 637         dev->req.bi_vcnt++;
 638         dev->req.bi_max_vecs++;
 639         dev->vec.bv_page = dev->page;
 640         dev->vec.bv_len = STRIPE_SIZE;
 641         dev->vec.bv_offset = 0;
 642
 643         dev->req.bi_sector = sh->sector;
 644         dev->req.bi_private = sh;
 645
 646         dev->flags = 0;
 647         dev->sector = compute_blocknr(sh, i);
 648 }
 649
 650 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 651 {
 652         char b[BDEVNAME_SIZE];
 653         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
 654         PRINTK("raid5: error called\n");
 655
 656         if (!test_bit(Faulty, &rdev->flags)) {
 657                 mddev->sb_dirty = 1;
 658                 if (test_bit(In_sync, &rdev->flags)) {
 659                         conf->working_disks--;
 660                         mddev->degraded++;
 661                         conf->failed_disks++;
 662                         clear_bit(In_sync, &rdev->flags);
 663                         /*
 664                          * if recovery was running, make sure it aborts.
 665                          */
 666                         set_bit(MD_RECOVERY_ERR, &mddev->recovery);
 667                 }
 668                 set_bit(Faulty, &rdev->flags);
 669                 printk (KERN_ALERT
 670                         "raid5: Disk failure on %s, disabling device."
 671                         " Operation continuing on %d devices\n",
 672                         bdevname(rdev->bdev,b), conf->working_disks);
 673         }
 674 }
 675
 676 /*
 677  * Input: a 'big' sector number,
 678  * Output: index of the data and parity disk, and the sector # in them.
 679  */
 680 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
 681                         unsigned int data_disks, unsigned int * dd_idx,
 682                         unsigned int * pd_idx, raid5_conf_t *conf)
 683 {
 684         long stripe;
 685         unsigned long chunk_number;
 686         unsigned int chunk_offset;
 687         sector_t new_sector;
 688         int sectors_per_chunk = conf->chunk_size >> 9;
 689
 690         /* First compute the information on this sector */
 691
 692         /*
 693          * Compute the chunk number and the sector offset inside the chunk
 694          */
 695         chunk_offset = sector_div(r_sector, sectors_per_chunk);
 696         chunk_number = r_sector;
 697         BUG_ON(r_sector != chunk_number);
 698
 699         /*
 700          * Compute the stripe number
 701          */
 702         stripe = chunk_number / data_disks;
 703
 704         /*
 705          * Compute the data disk and parity disk indexes inside the stripe
 706          */
 707         *dd_idx = chunk_number % data_disks;
 708
 709         /*
 710          * Select the parity disk based on the user selected algorithm.
 711          */
 712         switch(conf->level) {
 713         case 4:
 714                 *pd_idx = data_disks;
 715                 break;
 716         case 5:
 717                 switch (conf->algorithm) {
 718                 case ALGORITHM_LEFT_ASYMMETRIC:
 719                         *pd_idx = data_disks - stripe % raid_disks;
 720                         if (*dd_idx >= *pd_idx)
 721                                 (*dd_idx)++;
 722                         break;
 723                 case ALGORITHM_RIGHT_ASYMMETRIC:
 724                         *pd_idx = stripe % raid_disks;
 725                         if (*dd_idx >= *pd_idx)
 726                                 (*dd_idx)++;
 727                         break;
 728                 case ALGORITHM_LEFT_SYMMETRIC:
 729                         *pd_idx = data_disks - stripe % raid_disks;
 730                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
 731                         break;
 732                 case ALGORITHM_RIGHT_SYMMETRIC:
 733                         *pd_idx = stripe % raid_disks;
 734                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
 735                         break;
 736                 default:
 737                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
 738                                 conf->algorithm);
 739                 }
 740                 break;
 741         case 6:
 742
 743                 /**** FIX THIS ****/
 744                 switch (conf->algorithm) {
 745                 case ALGORITHM_LEFT_ASYMMETRIC:
 746                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
 747                         if (*pd_idx == raid_disks-1)
 748                                 (*dd_idx)++;    /* Q D D D P */
 749                         else if (*dd_idx >= *pd_idx)
 750                                 (*dd_idx) += 2; /* D D P Q D */
 751                         break;
 752                 case ALGORITHM_RIGHT_ASYMMETRIC:
 753                         *pd_idx = stripe % raid_disks;
 754                         if (*pd_idx == raid_disks-1)
 755                                 (*dd_idx)++;    /* Q D D D P */
 756                         else if (*dd_idx >= *pd_idx)
 757                                 (*dd_idx) += 2; /* D D P Q D */
 758                         break;
 759                 case ALGORITHM_LEFT_SYMMETRIC:
 760                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
 761                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
 762                         break;
 763                 case ALGORITHM_RIGHT_SYMMETRIC:
 764                         *pd_idx = stripe % raid_disks;
 765                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
 766                         break;
 767                 default:
 768                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
 769                                 conf->algorithm);
 770                 }
 771                 break;
 772         }
 773
 774         /*
 775          * Finally, compute the new sector number
 776          */
 777         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
 778         return new_sector;
 779 }
 780
 781
 782 static sector_t compute_blocknr(struct stripe_head *sh, int i)
 783 {
 784         raid5_conf_t *conf = sh->raid_conf;
 785         int raid_disks = sh->disks, data_disks = raid_disks - 1;
 786         sector_t new_sector = sh->sector, check;
 787         int sectors_per_chunk = conf->chunk_size >> 9;
 788         sector_t stripe;
 789         int chunk_offset;
 790         int chunk_number, dummy1, dummy2, dd_idx = i;
 791         sector_t r_sector;
 792
 793
 794         chunk_offset = sector_div(new_sector, sectors_per_chunk);
 795         stripe = new_sector;
 796         BUG_ON(new_sector != stripe);
 797
 798         if (i == sh->pd_idx)
 799                 return 0;
 800         switch(conf->level) {
 801         case 4: break;
 802         case 5:
 803                 switch (conf->algorithm) {
 804                 case ALGORITHM_LEFT_ASYMMETRIC:
 805                 case ALGORITHM_RIGHT_ASYMMETRIC:
 806                         if (i > sh->pd_idx)
 807                                 i--;
 808                         break;
 809                 case ALGORITHM_LEFT_SYMMETRIC:
 810                 case ALGORITHM_RIGHT_SYMMETRIC:
 811                         if (i < sh->pd_idx)
 812                                 i += raid_disks;
 813                         i -= (sh->pd_idx + 1);
 814                         break;
 815                 default:
 816                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
 817                                conf->algorithm);
 818                 }
 819                 break;
 820         case 6:
 821                 data_disks = raid_disks - 2;
 822                 if (i == raid6_next_disk(sh->pd_idx, raid_disks))
 823                         return 0; /* It is the Q disk */
 824                 switch (conf->algorithm) {
 825                 case ALGORITHM_LEFT_ASYMMETRIC:
 826                 case ALGORITHM_RIGHT_ASYMMETRIC:
 827                         if (sh->pd_idx == raid_disks-1)
 828                                 i--;    /* Q D D D P */
 829                         else if (i > sh->pd_idx)
 830                                 i -= 2; /* D D P Q D */
 831                         break;
 832                 case ALGORITHM_LEFT_SYMMETRIC:
 833                 case ALGORITHM_RIGHT_SYMMETRIC:
 834                         if (sh->pd_idx == raid_disks-1)
 835                                 i--; /* Q D D D P */
 836                         else {
 837                                 /* D D P Q D */
 838                                 if (i < sh->pd_idx)
 839                                         i += raid_disks;
 840                                 i -= (sh->pd_idx + 2);
 841                         }
 842                         break;
 843                 default:
 844                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
 845                                 conf->algorithm);
 846                 }
 847                 break;
 848         }
 849
 850         chunk_number = stripe * data_disks + i;
 851         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
 852
 853         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
 854         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
 855                 printk(KERN_ERR "compute_blocknr: map not correct\n");
 856                 return 0;
 857         }
 858         return r_sector;
 859 }
 860
 861
 862
 863 /*
 864  * Copy data between a page in the stripe cache, and one or more bion
 865  * The page could align with the middle of the bio, or there could be
 866  * several bion, each with several bio_vecs, which cover part of the page
 867  * Multiple bion are linked together on bi_next.  There may be extras
 868  * at the end of this list.  We ignore them.
 869  */
 870 static void copy_data(int frombio, struct bio *bio,
 871                      struct page *page,
 872                      sector_t sector)
 873 {
 874         char *pa = page_address(page);
 875         struct bio_vec *bvl;
 876         int i;
 877         int page_offset;
 878
 879         if (bio->bi_sector >= sector)
 880                 page_offset = (signed)(bio->bi_sector - sector) * 512;
 881         else
 882                 page_offset = (signed)(sector - bio->bi_sector) * -512;
 883         bio_for_each_segment(bvl, bio, i) {
 884                 int len = bio_iovec_idx(bio,i)->bv_len;
 885                 int clen;
 886                 int b_offset = 0;
 887
 888                 if (page_offset < 0) {
 889                         b_offset = -page_offset;
 890                         page_offset += b_offset;
 891                         len -= b_offset;
 892                 }
 893
 894                 if (len > 0 && page_offset + len > STRIPE_SIZE)
 895                         clen = STRIPE_SIZE - page_offset;
 896                 else clen = len;
 897
 898                 if (clen > 0) {
 899                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
 900                         if (frombio)
 901                                 memcpy(pa+page_offset, ba+b_offset, clen);
 902                         else
 903                                 memcpy(ba+b_offset, pa+page_offset, clen);
 904                         __bio_kunmap_atomic(ba, KM_USER0);
 905                 }
 906                 if (clen < len) /* hit end of page */
 907                         break;
 908                 page_offset +=  len;
 909         }
 910 }
 911
 912 #define check_xor()     do {                                            \
 913                            if (count == MAX_XOR_BLOCKS) {               \
 914                                 xor_block(count, STRIPE_SIZE, ptr);     \
 915                                 count = 1;                              \
 916                            }                                            \
 917                         } while(0)
 918
 919
 920 static void compute_block(struct stripe_head *sh, int dd_idx)
 921 {
 922         int i, count, disks = sh->disks;
 923         void *ptr[MAX_XOR_BLOCKS], *p;
 924
 925         PRINTK("compute_block, stripe %llu, idx %d\n",
 926                 (unsigned long long)sh->sector, dd_idx);
 927
 928         ptr[0] = page_address(sh->dev[dd_idx].page);
 929         memset(ptr[0], 0, STRIPE_SIZE);
 930         count = 1;
 931         for (i = disks ; i--; ) {
 932                 if (i == dd_idx)
 933                         continue;
 934                 p = page_address(sh->dev[i].page);
 935                 if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
 936                         ptr[count++] = p;
 937                 else
 938                         printk(KERN_ERR "compute_block() %d, stripe %llu, %d"
 939                                 " not present\n", dd_idx,
 940                                 (unsigned long long)sh->sector, i);
 941
 942                 check_xor();
 943         }
 944         if (count != 1)
 945                 xor_block(count, STRIPE_SIZE, ptr);
 946         set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
 947 }
 948
 949 static void compute_parity5(struct stripe_head *sh, int method)
 950 {
 951         raid5_conf_t *conf = sh->raid_conf;
 952         int i, pd_idx = sh->pd_idx, disks = sh->disks, count;
 953         void *ptr[MAX_XOR_BLOCKS];
 954         struct bio *chosen;
 955
 956         PRINTK("compute_parity5, stripe %llu, method %d\n",
 957                 (unsigned long long)sh->sector, method);
 958
 959         count = 1;
 960         ptr[0] = page_address(sh->dev[pd_idx].page);
 961         switch(method) {
 962         case READ_MODIFY_WRITE:
 963                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags));
 964                 for (i=disks ; i-- ;) {
 965                         if (i==pd_idx)
 966                                 continue;
 967                         if (sh->dev[i].towrite &&
 968                             test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
 969                                 ptr[count++] = page_address(sh->dev[i].page);
 970                                 chosen = sh->dev[i].towrite;
 971                                 sh->dev[i].towrite = NULL;
 972
 973                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 974                                         wake_up(&conf->wait_for_overlap);
 975
 976                                 BUG_ON(sh->dev[i].written);
 977                                 sh->dev[i].written = chosen;
 978                                 check_xor();
 979                         }
 980                 }
 981                 break;
 982         case RECONSTRUCT_WRITE:
 983                 memset(ptr[0], 0, STRIPE_SIZE);
 984                 for (i= disks; i-- ;)
 985                         if (i!=pd_idx && sh->dev[i].towrite) {
 986                                 chosen = sh->dev[i].towrite;
 987                                 sh->dev[i].towrite = NULL;
 988
 989                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 990                                         wake_up(&conf->wait_for_overlap);
 991
 992                                 BUG_ON(sh->dev[i].written);
 993                                 sh->dev[i].written = chosen;
 994                         }
 995                 break;
 996         case CHECK_PARITY:
 997                 break;
 998         }
 999         if (count>1) {
1000                 xor_block(count, STRIPE_SIZE, ptr);
1001                 count = 1;
1002         }
1003
1004         for (i = disks; i--;)
1005                 if (sh->dev[i].written) {
1006                         sector_t sector = sh->dev[i].sector;
1007                         struct bio *wbi = sh->dev[i].written;
1008                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1009                                 copy_data(1, wbi, sh->dev[i].page, sector);
1010                                 wbi = r5_next_bio(wbi, sector);
1011                         }
1012
1013                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1014                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1015                 }
1016
1017         switch(method) {
1018         case RECONSTRUCT_WRITE:
1019         case CHECK_PARITY:
1020                 for (i=disks; i--;)
1021                         if (i != pd_idx) {
1022                                 ptr[count++] = page_address(sh->dev[i].page);
1023                                 check_xor();
1024                         }
1025                 break;
1026         case READ_MODIFY_WRITE:
1027                 for (i = disks; i--;)
1028                         if (sh->dev[i].written) {
1029                                 ptr[count++] = page_address(sh->dev[i].page);
1030                                 check_xor();
1031                         }
1032         }
1033         if (count != 1)
1034                 xor_block(count, STRIPE_SIZE, ptr);
1035
1036         if (method != CHECK_PARITY) {
1037                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1038                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1039         } else
1040                 clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1041 }
1042
1043 static void compute_parity6(struct stripe_head *sh, int method)
1044 {
1045         raid6_conf_t *conf = sh->raid_conf;
1046         int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = conf->raid_disks, count;
1047         struct bio *chosen;
1048         /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1049         void *ptrs[disks];
1050
1051         qd_idx = raid6_next_disk(pd_idx, disks);
1052         d0_idx = raid6_next_disk(qd_idx, disks);
1053
1054         PRINTK("compute_parity, stripe %llu, method %d\n",
1055                 (unsigned long long)sh->sector, method);
1056
1057         switch(method) {
1058         case READ_MODIFY_WRITE:
1059                 BUG();          /* READ_MODIFY_WRITE N/A for RAID-6 */
1060         case RECONSTRUCT_WRITE:
1061                 for (i= disks; i-- ;)
1062                         if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
1063                                 chosen = sh->dev[i].towrite;
1064                                 sh->dev[i].towrite = NULL;
1065
1066                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1067                                         wake_up(&conf->wait_for_overlap);
1068
1069                                 if (sh->dev[i].written) BUG();
1070                                 sh->dev[i].written = chosen;
1071                         }
1072                 break;
1073         case CHECK_PARITY:
1074                 BUG();          /* Not implemented yet */
1075         }
1076
1077         for (i = disks; i--;)
1078                 if (sh->dev[i].written) {
1079                         sector_t sector = sh->dev[i].sector;
1080                         struct bio *wbi = sh->dev[i].written;
1081                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1082                                 copy_data(1, wbi, sh->dev[i].page, sector);
1083                                 wbi = r5_next_bio(wbi, sector);
1084                         }
1085
1086                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1087                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1088                 }
1089
1090 //      switch(method) {
1091 //      case RECONSTRUCT_WRITE:
1092 //      case CHECK_PARITY:
1093 //      case UPDATE_PARITY:
1094                 /* Note that unlike RAID-5, the ordering of the disks matters greatly. */
1095                 /* FIX: Is this ordering of drives even remotely optimal? */
1096                 count = 0;
1097                 i = d0_idx;
1098                 do {
1099                         ptrs[count++] = page_address(sh->dev[i].page);
1100                         if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1101                                 printk("block %d/%d not uptodate on parity calc\n", i,count);
1102                         i = raid6_next_disk(i, disks);
1103                 } while ( i != d0_idx );
1104 //              break;
1105 //      }
1106
1107         raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
1108
1109         switch(method) {
1110         case RECONSTRUCT_WRITE:
1111                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1112                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1113                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1114                 set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
1115                 break;
1116         case UPDATE_PARITY:
1117                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1118                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1119                 break;
1120         }
1121 }
1122
1123
1124 /* Compute one missing block */
1125 static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
1126 {
1127         raid6_conf_t *conf = sh->raid_conf;
1128         int i, count, disks = conf->raid_disks;
1129         void *ptr[MAX_XOR_BLOCKS], *p;
1130         int pd_idx = sh->pd_idx;
1131         int qd_idx = raid6_next_disk(pd_idx, disks);
1132
1133         PRINTK("compute_block_1, stripe %llu, idx %d\n",
1134                 (unsigned long long)sh->sector, dd_idx);
1135
1136         if ( dd_idx == qd_idx ) {
1137                 /* We're actually computing the Q drive */
1138                 compute_parity6(sh, UPDATE_PARITY);
1139         } else {
1140                 ptr[0] = page_address(sh->dev[dd_idx].page);
1141                 if (!nozero) memset(ptr[0], 0, STRIPE_SIZE);
1142                 count = 1;
1143                 for (i = disks ; i--; ) {
1144                         if (i == dd_idx || i == qd_idx)
1145                                 continue;
1146                         p = page_address(sh->dev[i].page);
1147                         if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
1148                                 ptr[count++] = p;
1149                         else
1150                                 printk("compute_block() %d, stripe %llu, %d"
1151                                        " not present\n", dd_idx,
1152                                        (unsigned long long)sh->sector, i);
1153
1154                         check_xor();
1155                 }
1156                 if (count != 1)
1157                         xor_block(count, STRIPE_SIZE, ptr);
1158                 if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1159                 else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1160         }
1161 }
1162
1163 /* Compute two missing blocks */
1164 static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
1165 {
1166         raid6_conf_t *conf = sh->raid_conf;
1167         int i, count, disks = conf->raid_disks;
1168         int pd_idx = sh->pd_idx;
1169         int qd_idx = raid6_next_disk(pd_idx, disks);
1170         int d0_idx = raid6_next_disk(qd_idx, disks);
1171         int faila, failb;
1172
1173         /* faila and failb are disk numbers relative to d0_idx */
1174         /* pd_idx become disks-2 and qd_idx become disks-1 */
1175         faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
1176         failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
1177
1178         BUG_ON(faila == failb);
1179         if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
1180
1181         PRINTK("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
1182                (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
1183
1184         if ( failb == disks-1 ) {
1185                 /* Q disk is one of the missing disks */
1186                 if ( faila == disks-2 ) {
1187                         /* Missing P+Q, just recompute */
1188                         compute_parity6(sh, UPDATE_PARITY);
1189                         return;
1190                 } else {
1191                         /* We're missing D+Q; recompute D from P */
1192                         compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
1193                         compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
1194                         return;
1195                 }
1196         }
1197
1198         /* We're missing D+P or D+D; build pointer table */
1199         {
1200                 /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1201                 void *ptrs[disks];
1202
1203                 count = 0;
1204                 i = d0_idx;
1205                 do {
1206                         ptrs[count++] = page_address(sh->dev[i].page);
1207                         i = raid6_next_disk(i, disks);
1208                         if (i != dd_idx1 && i != dd_idx2 &&
1209                             !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1210                                 printk("compute_2 with missing block %d/%d\n", count, i);
1211                 } while ( i != d0_idx );
1212
1213                 if ( failb == disks-2 ) {
1214                         /* We're missing D+P. */
1215                         raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
1216                 } else {
1217                         /* We're missing D+D. */
1218                         raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
1219                 }
1220
1221                 /* Both the above update both missing blocks */
1222                 set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
1223                 set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
1224         }
1225 }
1226
1227
1228
1229 /*
1230  * Each stripe/dev can have one or more bion attached.
1231  * toread/towrite point to the first in a chain.
1232  * The bi_next chain must be in order.
1233  */
1234 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
1235 {
1236         struct bio **bip;
1237         raid5_conf_t *conf = sh->raid_conf;
1238         int firstwrite=0;
1239
1240         PRINTK("adding bh b#%llu to stripe s#%llu\n",
1241                 (unsigned long long)bi->bi_sector,
1242                 (unsigned long long)sh->sector);
1243
1244
1245         spin_lock(&sh->lock);
1246         spin_lock_irq(&conf->device_lock);
1247         if (forwrite) {
1248                 bip = &sh->dev[dd_idx].towrite;
1249                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
1250                         firstwrite = 1;
1251         } else
1252                 bip = &sh->dev[dd_idx].toread;
1253         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
1254                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
1255                         goto overlap;
1256                 bip = & (*bip)->bi_next;
1257         }
1258         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
1259                 goto overlap;
1260
1261         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
1262         if (*bip)
1263                 bi->bi_next = *bip;
1264         *bip = bi;
1265         bi->bi_phys_segments ++;
1266         spin_unlock_irq(&conf->device_lock);
1267         spin_unlock(&sh->lock);
1268
1269         PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n",
1270                 (unsigned long long)bi->bi_sector,
1271                 (unsigned long long)sh->sector, dd_idx);
1272
1273         if (conf->mddev->bitmap && firstwrite) {
1274                 sh->bm_seq = conf->seq_write;
1275                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
1276                                   STRIPE_SECTORS, 0);
1277                 set_bit(STRIPE_BIT_DELAY, &sh->state);
1278         }
1279
1280         if (forwrite) {
1281                 /* check if page is covered */
1282                 sector_t sector = sh->dev[dd_idx].sector;
1283                 for (bi=sh->dev[dd_idx].towrite;
1284                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
1285                              bi && bi->bi_sector <= sector;
1286                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
1287                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
1288                                 sector = bi->bi_sector + (bi->bi_size>>9);
1289                 }
1290                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
1291                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
1292         }
1293         return 1;
1294
1295  overlap:
1296         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1297         spin_unlock_irq(&conf->device_lock);
1298         spin_unlock(&sh->lock);
1299         return 0;
1300 }
1301
1302 static void end_reshape(raid5_conf_t *conf);
1303
1304 static int page_is_zero(struct page *p)
1305 {
1306         char *a = page_address(p);
1307         return ((*(u32*)a) == 0 &&
1308                 memcmp(a, a+4, STRIPE_SIZE-4)==0);
1309 }
1310
1311 static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
1312 {
1313         int sectors_per_chunk = conf->chunk_size >> 9;
1314         sector_t x = stripe;
1315         int pd_idx, dd_idx;
1316         int chunk_offset = sector_div(x, sectors_per_chunk);
1317         stripe = x;
1318         raid5_compute_sector(stripe*(disks-1)*sectors_per_chunk
1319                              + chunk_offset, disks, disks-1, &dd_idx, &pd_idx, conf);
1320         return pd_idx;
1321 }
1322
1323
1324 /*
1325  * handle_stripe - do things to a stripe.
1326  *
1327  * We lock the stripe and then examine the state of various bits
1328  * to see what needs to be done.
1329  * Possible results:
1330  *    return some read request which now have data
1331  *    return some write requests which are safely on disc
1332  *    schedule a read on some buffers
1333  *    schedule a write of some buffers
1334  *    return confirmation of parity correctness
1335  *
1336  * Parity calculations are done inside the stripe lock
1337  * buffers are taken off read_list or write_list, and bh_cache buffers
1338  * get BH_Lock set before the stripe lock is released.
1339  *
1340  */
1341
1342 static void handle_stripe5(struct stripe_head *sh)
1343 {
1344         raid5_conf_t *conf = sh->raid_conf;
1345         int disks = sh->disks;
1346         struct bio *return_bi= NULL;
1347         struct bio *bi;
1348         int i;
1349         int syncing, expanding, expanded;
1350         int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
1351         int non_overwrite = 0;
1352         int failed_num=0;
1353         struct r5dev *dev;
1354
1355         PRINTK("handling stripe %llu, cnt=%d, pd_idx=%d\n",
1356                 (unsigned long long)sh->sector, atomic_read(&sh->count),
1357                 sh->pd_idx);
1358
1359         spin_lock(&sh->lock);
1360         clear_bit(STRIPE_HANDLE, &sh->state);
1361         clear_bit(STRIPE_DELAYED, &sh->state);
1362
1363         syncing = test_bit(STRIPE_SYNCING, &sh->state);
1364         expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
1365         expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
1366         /* Now to look around and see what can be done */
1367
1368         rcu_read_lock();
1369         for (i=disks; i--; ) {
1370                 mdk_rdev_t *rdev;
1371                 dev = &sh->dev[i];
1372                 clear_bit(R5_Insync, &dev->flags);
1373
1374                 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
1375                         i, dev->flags, dev->toread, dev->towrite, dev->written);
1376                 /* maybe we can reply to a read */
1377                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
1378                         struct bio *rbi, *rbi2;
1379                         PRINTK("Return read for disc %d\n", i);
1380                         spin_lock_irq(&conf->device_lock);
1381                         rbi = dev->toread;
1382                         dev->toread = NULL;
1383                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1384                                 wake_up(&conf->wait_for_overlap);
1385                         spin_unlock_irq(&conf->device_lock);
1386                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1387                                 copy_data(0, rbi, dev->page, dev->sector);
1388                                 rbi2 = r5_next_bio(rbi, dev->sector);
1389                                 spin_lock_irq(&conf->device_lock);
1390                                 if (--rbi->bi_phys_segments == 0) {
1391                                         rbi->bi_next = return_bi;
1392                                         return_bi = rbi;
1393                                 }
1394                                 spin_unlock_irq(&conf->device_lock);
1395                                 rbi = rbi2;
1396                         }
1397                 }
1398
1399                 /* now count some things */
1400                 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
1401                 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
1402
1403
1404                 if (dev->toread) to_read++;
1405                 if (dev->towrite) {
1406                         to_write++;
1407                         if (!test_bit(R5_OVERWRITE, &dev->flags))
1408                                 non_overwrite++;
1409                 }
1410                 if (dev->written) written++;
1411                 rdev = rcu_dereference(conf->disks[i].rdev);
1412                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
1413                         /* The ReadError flag will just be confusing now */
1414                         clear_bit(R5_ReadError, &dev->flags);
1415                         clear_bit(R5_ReWrite, &dev->flags);
1416                 }
1417                 if (!rdev || !test_bit(In_sync, &rdev->flags)
1418                     || test_bit(R5_ReadError, &dev->flags)) {
1419                         failed++;
1420                         failed_num = i;
1421                 } else
1422                         set_bit(R5_Insync, &dev->flags);
1423         }
1424         rcu_read_unlock();
1425         PRINTK("locked=%d uptodate=%d to_read=%d"
1426                 " to_write=%d failed=%d failed_num=%d\n",
1427                 locked, uptodate, to_read, to_write, failed, failed_num);
1428         /* check if the array has lost two devices and, if so, some requests might
1429          * need to be failed
1430          */
1431         if (failed > 1 && to_read+to_write+written) {
1432                 for (i=disks; i--; ) {
1433                         int bitmap_end = 0;
1434
1435                         if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1436                                 mdk_rdev_t *rdev;
1437                                 rcu_read_lock();
1438                                 rdev = rcu_dereference(conf->disks[i].rdev);
1439                                 if (rdev && test_bit(In_sync, &rdev->flags))
1440                                         /* multiple read failures in one stripe */
1441                                         md_error(conf->mddev, rdev);
1442                                 rcu_read_unlock();
1443                         }
1444
1445                         spin_lock_irq(&conf->device_lock);
1446                         /* fail all writes first */
1447                         bi = sh->dev[i].towrite;
1448                         sh->dev[i].towrite = NULL;
1449                         if (bi) { to_write--; bitmap_end = 1; }
1450
1451                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1452                                 wake_up(&conf->wait_for_overlap);
1453
1454                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1455                                 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1456                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1457                                 if (--bi->bi_phys_segments == 0) {
1458                                         md_write_end(conf->mddev);
1459                                         bi->bi_next = return_bi;
1460                                         return_bi = bi;
1461                                 }
1462                                 bi = nextbi;
1463                         }
1464                         /* and fail all 'written' */
1465                         bi = sh->dev[i].written;
1466                         sh->dev[i].written = NULL;
1467                         if (bi) bitmap_end = 1;
1468                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
1469                                 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
1470                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
1471                                 if (--bi->bi_phys_segments == 0) {
1472                                         md_write_end(conf->mddev);
1473                                         bi->bi_next = return_bi;
1474                                         return_bi = bi;
1475                                 }
1476                                 bi = bi2;
1477                         }
1478
1479                         /* fail any reads if this device is non-operational */
1480                         if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
1481                             test_bit(R5_ReadError, &sh->dev[i].flags)) {
1482                                 bi = sh->dev[i].toread;
1483                                 sh->dev[i].toread = NULL;
1484                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1485                                         wake_up(&conf->wait_for_overlap);
1486                                 if (bi) to_read--;
1487                                 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1488                                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1489                                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1490                                         if (--bi->bi_phys_segments == 0) {
1491                                                 bi->bi_next = return_bi;
1492                                                 return_bi = bi;
1493                                         }
1494                                         bi = nextbi;
1495                                 }
1496                         }
1497                         spin_unlock_irq(&conf->device_lock);
1498                         if (bitmap_end)
1499                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1500                                                 STRIPE_SECTORS, 0, 0);
1501                 }
1502         }
1503         if (failed > 1 && syncing) {
1504                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
1505                 clear_bit(STRIPE_SYNCING, &sh->state);
1506                 syncing = 0;
1507         }
1508
1509         /* might be able to return some write requests if the parity block
1510          * is safe, or on a failed drive
1511          */
1512         dev = &sh->dev[sh->pd_idx];
1513         if ( written &&
1514              ( (test_bit(R5_Insync, &dev->flags) && !test_bit(R5_LOCKED, &dev->flags) &&
1515                 test_bit(R5_UPTODATE, &dev->flags))
1516                || (failed == 1 && failed_num == sh->pd_idx))
1517             ) {
1518             /* any written block on an uptodate or failed drive can be returned.
1519              * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
1520              * never LOCKED, so we don't need to test 'failed' directly.
1521              */
1522             for (i=disks; i--; )
1523                 if (sh->dev[i].written) {
1524                     dev = &sh->dev[i];
1525                     if (!test_bit(R5_LOCKED, &dev->flags) &&
1526                          test_bit(R5_UPTODATE, &dev->flags) ) {
1527                         /* We can return any write requests */
1528                             struct bio *wbi, *wbi2;
1529                             int bitmap_end = 0;
1530                             PRINTK("Return write for disc %d\n", i);
1531                             spin_lock_irq(&conf->device_lock);
1532                             wbi = dev->written;
1533                             dev->written = NULL;
1534                             while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1535                                     wbi2 = r5_next_bio(wbi, dev->sector);
1536                                     if (--wbi->bi_phys_segments == 0) {
1537                                             md_write_end(conf->mddev);
1538                                             wbi->bi_next = return_bi;
1539                                             return_bi = wbi;
1540                                     }
1541                                     wbi = wbi2;
1542                             }
1543                             if (dev->towrite == NULL)
1544                                     bitmap_end = 1;
1545                             spin_unlock_irq(&conf->device_lock);
1546                             if (bitmap_end)
1547                                     bitmap_endwrite(conf->mddev->bitmap, sh->sector,
1548                                                     STRIPE_SECTORS,
1549                                                     !test_bit(STRIPE_DEGRADED, &sh->state), 0);
1550                     }
1551                 }
1552         }
1553
1554         /* Now we might consider reading some blocks, either to check/generate
1555          * parity, or to satisfy requests
1556          * or to load a block that is being partially written.
1557          */
1558         if (to_read || non_overwrite || (syncing && (uptodate < disks)) || expanding) {
1559                 for (i=disks; i--;) {
1560                         dev = &sh->dev[i];
1561                         if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1562                             (dev->toread ||
1563                              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1564                              syncing ||
1565                              expanding ||
1566                              (failed && (sh->dev[failed_num].toread ||
1567                                          (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags))))
1568                                     )
1569                                 ) {
1570                                 /* we would like to get this block, possibly
1571                                  * by computing it, but we might not be able to
1572                                  */
1573                                 if (uptodate == disks-1) {
1574                                         PRINTK("Computing block %d\n", i);
1575                                         compute_block(sh, i);
1576                                         uptodate++;
1577                                 } else if (test_bit(R5_Insync, &dev->flags)) {
1578                                         set_bit(R5_LOCKED, &dev->flags);
1579                                         set_bit(R5_Wantread, &dev->flags);
1580 #if 0
1581                                         /* if I am just reading this block and we don't have
1582                                            a failed drive, or any pending writes then sidestep the cache */
1583                                         if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
1584                                             ! syncing && !failed && !to_write) {
1585                                                 sh->bh_cache[i]->b_page =  sh->bh_read[i]->b_page;
1586                                                 sh->bh_cache[i]->b_data =  sh->bh_read[i]->b_data;
1587                                         }
1588 #endif
1589                                         locked++;
1590                                         PRINTK("Reading block %d (sync=%d)\n",
1591                                                 i, syncing);
1592                                 }
1593                         }
1594                 }
1595                 set_bit(STRIPE_HANDLE, &sh->state);
1596         }
1597
1598         /* now to consider writing and what else, if anything should be read */
1599         if (to_write) {
1600                 int rmw=0, rcw=0;
1601                 for (i=disks ; i--;) {
1602                         /* would I have to read this buffer for read_modify_write */
1603                         dev = &sh->dev[i];
1604                         if ((dev->towrite || i == sh->pd_idx) &&
1605                             (!test_bit(R5_LOCKED, &dev->flags)
1606 #if 0
1607 || sh->bh_page[i]!=bh->b_page
1608 #endif
1609                                     ) &&
1610                             !test_bit(R5_UPTODATE, &dev->flags)) {
1611                                 if (test_bit(R5_Insync, &dev->flags)
1612 /*                                  && !(!mddev->insync && i == sh->pd_idx) */
1613                                         )
1614                                         rmw++;
1615                                 else rmw += 2*disks;  /* cannot read it */
1616                         }
1617                         /* Would I have to read this buffer for reconstruct_write */
1618                         if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1619                             (!test_bit(R5_LOCKED, &dev->flags)
1620 #if 0
1621 || sh->bh_page[i] != bh->b_page
1622 #endif
1623                                     ) &&
1624                             !test_bit(R5_UPTODATE, &dev->flags)) {
1625                                 if (test_bit(R5_Insync, &dev->flags)) rcw++;
1626                                 else rcw += 2*disks;
1627                         }
1628                 }
1629                 PRINTK("for sector %llu, rmw=%d rcw=%d\n",
1630                         (unsigned long long)sh->sector, rmw, rcw);
1631                 set_bit(STRIPE_HANDLE, &sh->state);
1632                 if (rmw < rcw && rmw > 0)
1633                         /* prefer read-modify-write, but need to get some data */
1634                         for (i=disks; i--;) {
1635                                 dev = &sh->dev[i];
1636                                 if ((dev->towrite || i == sh->pd_idx) &&
1637                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1638                                     test_bit(R5_Insync, &dev->flags)) {
1639                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1640                                         {
1641                                                 PRINTK("Read_old block %d for r-m-w\n", i);
1642                                                 set_bit(R5_LOCKED, &dev->flags);
1643                                                 set_bit(R5_Wantread, &dev->flags);
1644                                                 locked++;
1645                                         } else {
1646                                                 set_bit(STRIPE_DELAYED, &sh->state);
1647                                                 set_bit(STRIPE_HANDLE, &sh->state);
1648                                         }
1649                                 }
1650                         }
1651                 if (rcw <= rmw && rcw > 0)
1652                         /* want reconstruct write, but need to get some data */
1653                         for (i=disks; i--;) {
1654                                 dev = &sh->dev[i];
1655                                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1656                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1657                                     test_bit(R5_Insync, &dev->flags)) {
1658                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1659                                         {
1660                                                 PRINTK("Read_old block %d for Reconstruct\n", i);
1661                                                 set_bit(R5_LOCKED, &dev->flags);
1662                                                 set_bit(R5_Wantread, &dev->flags);
1663                                                 locked++;
1664                                         } else {
1665                                                 set_bit(STRIPE_DELAYED, &sh->state);
1666                                                 set_bit(STRIPE_HANDLE, &sh->state);
1667                                         }
1668                                 }
1669                         }
1670                 /* now if nothing is locked, and if we have enough data, we can start a write request */
1671                 if (locked == 0 && (rcw == 0 ||rmw == 0) &&
1672                     !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
1673                         PRINTK("Computing parity...\n");
1674                         compute_parity5(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
1675                         /* now every locked buffer is ready to be written */
1676                         for (i=disks; i--;)
1677                                 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
1678                                         PRINTK("Writing block %d\n", i);
1679                                         locked++;
1680                                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
1681                                         if (!test_bit(R5_Insync, &sh->dev[i].flags)
1682                                             || (i==sh->pd_idx && failed == 0))
1683                                                 set_bit(STRIPE_INSYNC, &sh->state);
1684                                 }
1685                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
1686                                 atomic_dec(&conf->preread_active_stripes);
1687                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
1688                                         md_wakeup_thread(conf->mddev->thread);
1689                         }
1690                 }
1691         }
1692
1693         /* maybe we need to check and possibly fix the parity for this stripe
1694          * Any reads will already have been scheduled, so we just see if enough data
1695          * is available
1696          */
1697         if (syncing && locked == 0 &&
1698             !test_bit(STRIPE_INSYNC, &sh->state)) {
1699                 set_bit(STRIPE_HANDLE, &sh->state);
1700                 if (failed == 0) {
1701                         BUG_ON(uptodate != disks);
1702                         compute_parity5(sh, CHECK_PARITY);
1703                         uptodate--;
1704                         if (page_is_zero(sh->dev[sh->pd_idx].page)) {
1705                                 /* parity is correct (on disc, not in buffer any more) */
1706                                 set_bit(STRIPE_INSYNC, &sh->state);
1707                         } else {
1708                                 conf->mddev->resync_mismatches += STRIPE_SECTORS;
1709                                 if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
1710                                         /* don't try to repair!! */
1711                                         set_bit(STRIPE_INSYNC, &sh->state);
1712                                 else {
1713                                         compute_block(sh, sh->pd_idx);
1714                                         uptodate++;
1715                                 }
1716                         }
1717                 }
1718                 if (!test_bit(STRIPE_INSYNC, &sh->state)) {
1719                         /* either failed parity check, or recovery is happening */
1720                         if (failed==0)
1721                                 failed_num = sh->pd_idx;
1722                         dev = &sh->dev[failed_num];
1723                         BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
1724                         BUG_ON(uptodate != disks);
1725
1726                         set_bit(R5_LOCKED, &dev->flags);
1727                         set_bit(R5_Wantwrite, &dev->flags);
1728                         clear_bit(STRIPE_DEGRADED, &sh->state);
1729                         locked++;
1730                         set_bit(STRIPE_INSYNC, &sh->state);
1731                 }
1732         }
1733         if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
1734                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
1735                 clear_bit(STRIPE_SYNCING, &sh->state);
1736         }
1737
1738         /* If the failed drive is just a ReadError, then we might need to progress
1739          * the repair/check process
1740          */
1741         if (failed == 1 && ! conf->mddev->ro &&
1742             test_bit(R5_ReadError, &sh->dev[failed_num].flags)
1743             && !test_bit(R5_LOCKED, &sh->dev[failed_num].flags)
1744             && test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)
1745                 ) {
1746                 dev = &sh->dev[failed_num];
1747                 if (!test_bit(R5_ReWrite, &dev->flags)) {
1748                         set_bit(R5_Wantwrite, &dev->flags);
1749                         set_bit(R5_ReWrite, &dev->flags);
1750                         set_bit(R5_LOCKED, &dev->flags);
1751                         locked++;
1752                 } else {
1753                         /* let's read it back */
1754                         set_bit(R5_Wantread, &dev->flags);
1755                         set_bit(R5_LOCKED, &dev->flags);
1756                         locked++;
1757                 }
1758         }
1759
1760         if (expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
1761                 /* Need to write out all blocks after computing parity */
1762                 sh->disks = conf->raid_disks;
1763                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf, conf->raid_disks);
1764                 compute_parity5(sh, RECONSTRUCT_WRITE);
1765                 for (i= conf->raid_disks; i--;) {
1766                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1767                         locked++;
1768                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
1769                 }
1770                 clear_bit(STRIPE_EXPANDING, &sh->state);
1771         } else if (expanded) {
1772                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
1773                 atomic_dec(&conf->reshape_stripes);
1774                 wake_up(&conf->wait_for_overlap);
1775                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
1776         }
1777
1778         if (expanding && locked == 0) {
1779                 /* We have read all the blocks in this stripe and now we need to
1780                  * copy some of them into a target stripe for expand.
1781                  */
1782                 clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
1783                 for (i=0; i< sh->disks; i++)
1784                         if (i != sh->pd_idx) {
1785                                 int dd_idx, pd_idx, j;
1786                                 struct stripe_head *sh2;
1787
1788                                 sector_t bn = compute_blocknr(sh, i);
1789                                 sector_t s = raid5_compute_sector(bn, conf->raid_disks,
1790                                                                   conf->raid_disks-1,
1791                                                                   &dd_idx, &pd_idx, conf);
1792                                 sh2 = get_active_stripe(conf, s, conf->raid_disks, pd_idx, 1);
1793                                 if (sh2 == NULL)
1794                                         /* so far only the early blocks of this stripe
1795                                          * have been requested.  When later blocks
1796                                          * get requested, we will try again
1797                                          */
1798                                         continue;
1799                                 if(!test_bit(STRIPE_EXPANDING, &sh2->state) ||
1800                                    test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
1801                                         /* must have already done this block */
1802                                         release_stripe(sh2);
1803                                         continue;
1804                                 }
1805                                 memcpy(page_address(sh2->dev[dd_idx].page),
1806                                        page_address(sh->dev[i].page),
1807                                        STRIPE_SIZE);
1808                                 set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
1809                                 set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
1810                                 for (j=0; j<conf->raid_disks; j++)
1811                                         if (j != sh2->pd_idx &&
1812                                             !test_bit(R5_Expanded, &sh2->dev[j].flags))
1813                                                 break;
1814                                 if (j == conf->raid_disks) {
1815                                         set_bit(STRIPE_EXPAND_READY, &sh2->state);
1816                                         set_bit(STRIPE_HANDLE, &sh2->state);
1817                                 }
1818                                 release_stripe(sh2);
1819                         }
1820         }
1821
1822         spin_unlock(&sh->lock);
1823
1824         while ((bi=return_bi)) {
1825                 int bytes = bi->bi_size;
1826
1827                 return_bi = bi->bi_next;
1828                 bi->bi_next = NULL;
1829                 bi->bi_size = 0;
1830                 bi->bi_end_io(bi, bytes, 0);
1831         }
1832         for (i=disks; i-- ;) {
1833                 int rw;
1834                 struct bio *bi;
1835                 mdk_rdev_t *rdev;
1836                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
1837                         rw = 1;
1838                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1839                         rw = 0;
1840                 else
1841                         continue;
1842
1843                 bi = &sh->dev[i].req;
1844
1845                 bi->bi_rw = rw;
1846                 if (rw)
1847                         bi->bi_end_io = raid5_end_write_request;
1848                 else
1849                         bi->bi_end_io = raid5_end_read_request;
1850
1851                 rcu_read_lock();
1852                 rdev = rcu_dereference(conf->disks[i].rdev);
1853                 if (rdev && test_bit(Faulty, &rdev->flags))
1854                         rdev = NULL;
1855                 if (rdev)
1856                         atomic_inc(&rdev->nr_pending);
1857                 rcu_read_unlock();
1858
1859                 if (rdev) {
1860                         if (syncing || expanding || expanded)
1861                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1862
1863                         bi->bi_bdev = rdev->bdev;
1864                         PRINTK("for %llu schedule op %ld on disc %d\n",
1865                                 (unsigned long long)sh->sector, bi->bi_rw, i);
1866                         atomic_inc(&sh->count);
1867                         bi->bi_sector = sh->sector + rdev->data_offset;
1868                         bi->bi_flags = 1 << BIO_UPTODATE;
1869                         bi->bi_vcnt = 1;
1870                         bi->bi_max_vecs = 1;
1871                         bi->bi_idx = 0;
1872                         bi->bi_io_vec = &sh->dev[i].vec;
1873                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1874                         bi->bi_io_vec[0].bv_offset = 0;
1875                         bi->bi_size = STRIPE_SIZE;
1876                         bi->bi_next = NULL;
1877                         if (rw == WRITE &&
1878                             test_bit(R5_ReWrite, &sh->dev[i].flags))
1879                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1880                         generic_make_request(bi);
1881                 } else {
1882                         if (rw == 1)
1883                                 set_bit(STRIPE_DEGRADED, &sh->state);
1884                         PRINTK("skip op %ld on disc %d for sector %llu\n",
1885                                 bi->bi_rw, i, (unsigned long long)sh->sector);
1886                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1887                         set_bit(STRIPE_HANDLE, &sh->state);
1888                 }
1889         }
1890 }
1891
1892 static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
1893 {
1894         raid6_conf_t *conf = sh->raid_conf;
1895         int disks = conf->raid_disks;
1896         struct bio *return_bi= NULL;
1897         struct bio *bi;
1898         int i;
1899         int syncing;
1900         int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
1901         int non_overwrite = 0;
1902         int failed_num[2] = {0, 0};
1903         struct r5dev *dev, *pdev, *qdev;
1904         int pd_idx = sh->pd_idx;
1905         int qd_idx = raid6_next_disk(pd_idx, disks);
1906         int p_failed, q_failed;
1907
1908         PRINTK("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d, qd_idx=%d\n",
1909                (unsigned long long)sh->sector, sh->state, atomic_read(&sh->count),
1910                pd_idx, qd_idx);
1911
1912         spin_lock(&sh->lock);
1913         clear_bit(STRIPE_HANDLE, &sh->state);
1914         clear_bit(STRIPE_DELAYED, &sh->state);
1915
1916         syncing = test_bit(STRIPE_SYNCING, &sh->state);
1917         /* Now to look around and see what can be done */
1918
1919         rcu_read_lock();
1920         for (i=disks; i--; ) {
1921                 mdk_rdev_t *rdev;
1922                 dev = &sh->dev[i];
1923                 clear_bit(R5_Insync, &dev->flags);
1924
1925                 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
1926                         i, dev->flags, dev->toread, dev->towrite, dev->written);
1927                 /* maybe we can reply to a read */
1928                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
1929                         struct bio *rbi, *rbi2;
1930                         PRINTK("Return read for disc %d\n", i);
1931                         spin_lock_irq(&conf->device_lock);
1932                         rbi = dev->toread;
1933                         dev->toread = NULL;
1934                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1935                                 wake_up(&conf->wait_for_overlap);
1936                         spin_unlock_irq(&conf->device_lock);
1937                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1938                                 copy_data(0, rbi, dev->page, dev->sector);
1939                                 rbi2 = r5_next_bio(rbi, dev->sector);
1940                                 spin_lock_irq(&conf->device_lock);
1941                                 if (--rbi->bi_phys_segments == 0) {
1942                                         rbi->bi_next = return_bi;
1943                                         return_bi = rbi;
1944                                 }
1945                                 spin_unlock_irq(&conf->device_lock);
1946                                 rbi = rbi2;
1947                         }
1948                 }
1949
1950                 /* now count some things */
1951                 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
1952                 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
1953
1954
1955                 if (dev->toread) to_read++;
1956                 if (dev->towrite) {
1957                         to_write++;
1958                         if (!test_bit(R5_OVERWRITE, &dev->flags))
1959                                 non_overwrite++;
1960                 }
1961                 if (dev->written) written++;
1962                 rdev = rcu_dereference(conf->disks[i].rdev);
1963                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
1964                         /* The ReadError flag will just be confusing now */
1965                         clear_bit(R5_ReadError, &dev->flags);
1966                         clear_bit(R5_ReWrite, &dev->flags);
1967                 }
1968                 if (!rdev || !test_bit(In_sync, &rdev->flags)
1969                     || test_bit(R5_ReadError, &dev->flags)) {
1970                         if ( failed < 2 )
1971                                 failed_num[failed] = i;
1972                         failed++;
1973                 } else
1974                         set_bit(R5_Insync, &dev->flags);
1975         }
1976         rcu_read_unlock();
1977         PRINTK("locked=%d uptodate=%d to_read=%d"
1978                " to_write=%d failed=%d failed_num=%d,%d\n",
1979                locked, uptodate, to_read, to_write, failed,
1980                failed_num[0], failed_num[1]);
1981         /* check if the array has lost >2 devices and, if so, some requests might
1982          * need to be failed
1983          */
1984         if (failed > 2 && to_read+to_write+written) {
1985                 for (i=disks; i--; ) {
1986                         int bitmap_end = 0;
1987
1988                         if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1989                                 mdk_rdev_t *rdev;
1990                                 rcu_read_lock();
1991                                 rdev = rcu_dereference(conf->disks[i].rdev);
1992                                 if (rdev && test_bit(In_sync, &rdev->flags))
1993                                         /* multiple read failures in one stripe */
1994                                         md_error(conf->mddev, rdev);
1995                                 rcu_read_unlock();
1996                         }
1997
1998                         spin_lock_irq(&conf->device_lock);
1999                         /* fail all writes first */
2000                         bi = sh->dev[i].towrite;
2001                         sh->dev[i].towrite = NULL;
2002                         if (bi) { to_write--; bitmap_end = 1; }
2003
2004                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2005                                 wake_up(&conf->wait_for_overlap);
2006
2007                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
2008                                 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2009                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2010                                 if (--bi->bi_phys_segments == 0) {
2011                                         md_write_end(conf->mddev);
2012                                         bi->bi_next = return_bi;
2013                                         return_bi = bi;
2014                                 }
2015                                 bi = nextbi;
2016                         }
2017                         /* and fail all 'written' */
2018                         bi = sh->dev[i].written;
2019                         sh->dev[i].written = NULL;
2020                         if (bi) bitmap_end = 1;
2021                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
2022                                 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2023                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2024                                 if (--bi->bi_phys_segments == 0) {
2025                                         md_write_end(conf->mddev);
2026                                         bi->bi_next = return_bi;
2027                                         return_bi = bi;
2028                                 }
2029                                 bi = bi2;
2030                         }
2031
2032                         /* fail any reads if this device is non-operational */
2033                         if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2034                             test_bit(R5_ReadError, &sh->dev[i].flags)) {
2035                                 bi = sh->dev[i].toread;
2036                                 sh->dev[i].toread = NULL;
2037                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2038                                         wake_up(&conf->wait_for_overlap);
2039                                 if (bi) to_read--;
2040                                 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
2041                                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2042                                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2043                                         if (--bi->bi_phys_segments == 0) {
2044                                                 bi->bi_next = return_bi;
2045                                                 return_bi = bi;
2046                                         }
2047                                         bi = nextbi;
2048                                 }
2049                         }
2050                         spin_unlock_irq(&conf->device_lock);
2051                         if (bitmap_end)
2052                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2053                                                 STRIPE_SECTORS, 0, 0);
2054                 }
2055         }
2056         if (failed > 2 && syncing) {
2057                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2058                 clear_bit(STRIPE_SYNCING, &sh->state);
2059                 syncing = 0;
2060         }
2061
2062         /*
2063          * might be able to return some write requests if the parity blocks
2064          * are safe, or on a failed drive
2065          */
2066         pdev = &sh->dev[pd_idx];
2067         p_failed = (failed >= 1 && failed_num[0] == pd_idx)
2068                 || (failed >= 2 && failed_num[1] == pd_idx);
2069         qdev = &sh->dev[qd_idx];
2070         q_failed = (failed >= 1 && failed_num[0] == qd_idx)
2071                 || (failed >= 2 && failed_num[1] == qd_idx);
2072
2073         if ( written &&
2074              ( p_failed || ((test_bit(R5_Insync, &pdev->flags)
2075                              && !test_bit(R5_LOCKED, &pdev->flags)
2076                              && test_bit(R5_UPTODATE, &pdev->flags))) ) &&
2077              ( q_failed || ((test_bit(R5_Insync, &qdev->flags)
2078                              && !test_bit(R5_LOCKED, &qdev->flags)
2079                              && test_bit(R5_UPTODATE, &qdev->flags))) ) ) {
2080                 /* any written block on an uptodate or failed drive can be
2081                  * returned.  Note that if we 'wrote' to a failed drive,
2082                  * it will be UPTODATE, but never LOCKED, so we don't need
2083                  * to test 'failed' directly.
2084                  */
2085                 for (i=disks; i--; )
2086                         if (sh->dev[i].written) {
2087                                 dev = &sh->dev[i];
2088                                 if (!test_bit(R5_LOCKED, &dev->flags) &&
2089                                     test_bit(R5_UPTODATE, &dev->flags) ) {
2090                                         /* We can return any write requests */
2091                                         int bitmap_end = 0;
2092                                         struct bio *wbi, *wbi2;
2093                                         PRINTK("Return write for stripe %llu disc %d\n",
2094                                                (unsigned long long)sh->sector, i);
2095                                         spin_lock_irq(&conf->device_lock);
2096                                         wbi = dev->written;
2097                                         dev->written = NULL;
2098                                         while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
2099                                                 wbi2 = r5_next_bio(wbi, dev->sector);
2100                                                 if (--wbi->bi_phys_segments == 0) {
2101                                                         md_write_end(conf->mddev);
2102                                                         wbi->bi_next = return_bi;
2103                                                         return_bi = wbi;
2104                                                 }
2105                                                 wbi = wbi2;
2106                                         }
2107                                         if (dev->towrite == NULL)
2108                                                 bitmap_end = 1;
2109                                         spin_unlock_irq(&conf->device_lock);
2110                                         if (bitmap_end)
2111                                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2112                                                                 STRIPE_SECTORS,
2113                                                                 !test_bit(STRIPE_DEGRADED, &sh->state), 0);
2114                                 }
2115                         }
2116         }
2117
2118         /* Now we might consider reading some blocks, either to check/generate
2119          * parity, or to satisfy requests
2120          * or to load a block that is being partially written.
2121          */
2122         if (to_read || non_overwrite || (to_write && failed) || (syncing && (uptodate < disks))) {
2123                 for (i=disks; i--;) {
2124                         dev = &sh->dev[i];
2125                         if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
2126                             (dev->toread ||
2127                              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2128                              syncing ||
2129                              (failed >= 1 && (sh->dev[failed_num[0]].toread || to_write)) ||
2130                              (failed >= 2 && (sh->dev[failed_num[1]].toread || to_write))
2131                                     )
2132                                 ) {
2133                                 /* we would like to get this block, possibly
2134                                  * by computing it, but we might not be able to
2135                                  */
2136                                 if (uptodate == disks-1) {
2137                                         PRINTK("Computing stripe %llu block %d\n",
2138                                                (unsigned long long)sh->sector, i);
2139                                         compute_block_1(sh, i, 0);
2140                                         uptodate++;
2141                                 } else if ( uptodate == disks-2 && failed >= 2 ) {
2142                                         /* Computing 2-failure is *very* expensive; only do it if failed >= 2 */
2143                                         int other;
2144                                         for (other=disks; other--;) {
2145                                                 if ( other == i )
2146                                                         continue;
2147                                                 if ( !test_bit(R5_UPTODATE, &sh->dev[other].flags) )
2148                                                         break;
2149                                         }
2150                                         BUG_ON(other < 0);
2151                                         PRINTK("Computing stripe %llu blocks %d,%d\n",
2152                                                (unsigned long long)sh->sector, i, other);
2153                                         compute_block_2(sh, i, other);
2154                                         uptodate += 2;
2155                                 } else if (test_bit(R5_Insync, &dev->flags)) {
2156                                         set_bit(R5_LOCKED, &dev->flags);
2157                                         set_bit(R5_Wantread, &dev->flags);
2158 #if 0
2159                                         /* if I am just reading this block and we don't have
2160                                            a failed drive, or any pending writes then sidestep the cache */
2161                                         if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
2162                                             ! syncing && !failed && !to_write) {
2163                                                 sh->bh_cache[i]->b_page =  sh->bh_read[i]->b_page;
2164                                                 sh->bh_cache[i]->b_data =  sh->bh_read[i]->b_data;
2165                                         }
2166 #endif
2167                                         locked++;
2168                                         PRINTK("Reading block %d (sync=%d)\n",
2169                                                 i, syncing);
2170                                 }
2171                         }
2172                 }
2173                 set_bit(STRIPE_HANDLE, &sh->state);
2174         }
2175
2176         /* now to consider writing and what else, if anything should be read */
2177         if (to_write) {
2178                 int rcw=0, must_compute=0;
2179                 for (i=disks ; i--;) {
2180                         dev = &sh->dev[i];
2181                         /* Would I have to read this buffer for reconstruct_write */
2182                         if (!test_bit(R5_OVERWRITE, &dev->flags)
2183                             && i != pd_idx && i != qd_idx
2184                             && (!test_bit(R5_LOCKED, &dev->flags)
2185 #if 0
2186                                 || sh->bh_page[i] != bh->b_page
2187 #endif
2188                                     ) &&
2189                             !test_bit(R5_UPTODATE, &dev->flags)) {
2190                                 if (test_bit(R5_Insync, &dev->flags)) rcw++;
2191                                 else {
2192                                         PRINTK("raid6: must_compute: disk %d flags=%#lx\n", i, dev->flags);
2193                                         must_compute++;
2194                                 }
2195                         }
2196                 }
2197                 PRINTK("for sector %llu, rcw=%d, must_compute=%d\n",
2198                        (unsigned long long)sh->sector, rcw, must_compute);
2199                 set_bit(STRIPE_HANDLE, &sh->state);
2200
2201                 if (rcw > 0)
2202                         /* want reconstruct write, but need to get some data */
2203                         for (i=disks; i--;) {
2204                                 dev = &sh->dev[i];
2205                                 if (!test_bit(R5_OVERWRITE, &dev->flags)
2206                                     && !(failed == 0 && (i == pd_idx || i == qd_idx))
2207                                     && !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
2208                                     test_bit(R5_Insync, &dev->flags)) {
2209                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
2210                                         {
2211                                                 PRINTK("Read_old stripe %llu block %d for Reconstruct\n",
2212                                                        (unsigned long long)sh->sector, i);
2213                                                 set_bit(R5_LOCKED, &dev->flags);
2214                                                 set_bit(R5_Wantread, &dev->flags);
2215                                                 locked++;
2216                                         } else {
2217                                                 PRINTK("Request delayed stripe %llu block %d for Reconstruct\n",
2218                                                        (unsigned long long)sh->sector, i);
2219                                                 set_bit(STRIPE_DELAYED, &sh->state);
2220                                                 set_bit(STRIPE_HANDLE, &sh->state);
2221                                         }
2222                                 }
2223                         }
2224                 /* now if nothing is locked, and if we have enough data, we can start a write request */
2225                 if (locked == 0 && rcw == 0 &&
2226                     !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
2227                         if ( must_compute > 0 ) {
2228                                 /* We have failed blocks and need to compute them */
2229                                 switch ( failed ) {
2230                                 case 0: BUG();
2231                                 case 1: compute_block_1(sh, failed_num[0], 0); break;
2232                                 case 2: compute_block_2(sh, failed_num[0], failed_num[1]); break;
2233                                 default: BUG(); /* This request should have been failed? */
2234                                 }
2235                         }
2236
2237                         PRINTK("Computing parity for stripe %llu\n", (unsigned long long)sh->sector);
2238                         compute_parity6(sh, RECONSTRUCT_WRITE);
2239                         /* now every locked buffer is ready to be written */
2240                         for (i=disks; i--;)
2241                                 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
2242                                         PRINTK("Writing stripe %llu block %d\n",
2243                                                (unsigned long long)sh->sector, i);
2244                                         locked++;
2245                                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
2246                                 }
2247                         /* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
2248                         set_bit(STRIPE_INSYNC, &sh->state);
2249
2250                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2251                                 atomic_dec(&conf->preread_active_stripes);
2252                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
2253                                         md_wakeup_thread(conf->mddev->thread);
2254                         }
2255                 }
2256         }
2257
2258         /* maybe we need to check and possibly fix the parity for this stripe
2259          * Any reads will already have been scheduled, so we just see if enough data
2260          * is available
2261          */
2262         if (syncing && locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state)) {
2263                 int update_p = 0, update_q = 0;
2264                 struct r5dev *dev;
2265
2266                 set_bit(STRIPE_HANDLE, &sh->state);
2267
2268                 BUG_ON(failed>2);
2269                 BUG_ON(uptodate < disks);
2270                 /* Want to check and possibly repair P and Q.
2271                  * However there could be one 'failed' device, in which
2272                  * case we can only check one of them, possibly using the
2273                  * other to generate missing data
2274                  */
2275
2276                 /* If !tmp_page, we cannot do the calculations,
2277                  * but as we have set STRIPE_HANDLE, we will soon be called
2278                  * by stripe_handle with a tmp_page - just wait until then.
2279                  */
2280                 if (tmp_page) {
2281                         if (failed == q_failed) {
2282                                 /* The only possible failed device holds 'Q', so it makes
2283                                  * sense to check P (If anything else were failed, we would
2284                                  * have used P to recreate it).
2285                                  */
2286                                 compute_block_1(sh, pd_idx, 1);
2287                                 if (!page_is_zero(sh->dev[pd_idx].page)) {
2288                                         compute_block_1(sh,pd_idx,0);
2289                                         update_p = 1;
2290                                 }
2291                         }
2292                         if (!q_failed && failed < 2) {
2293                                 /* q is not failed, and we didn't use it to generate
2294                                  * anything, so it makes sense to check it
2295                                  */
2296                                 memcpy(page_address(tmp_page),
2297                                        page_address(sh->dev[qd_idx].page),
2298                                        STRIPE_SIZE);
2299                                 compute_parity6(sh, UPDATE_PARITY);
2300                                 if (memcmp(page_address(tmp_page),
2301                                            page_address(sh->dev[qd_idx].page),
2302                                            STRIPE_SIZE)!= 0) {
2303                                         clear_bit(STRIPE_INSYNC, &sh->state);
2304                                         update_q = 1;
2305                                 }
2306                         }
2307                         if (update_p || update_q) {
2308                                 conf->mddev->resync_mismatches += STRIPE_SECTORS;
2309                                 if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2310                                         /* don't try to repair!! */
2311                                         update_p = update_q = 0;
2312                         }
2313
2314                         /* now write out any block on a failed drive,
2315                          * or P or Q if they need it
2316                          */
2317
2318                         if (failed == 2) {
2319                                 dev = &sh->dev[failed_num[1]];
2320                                 locked++;
2321                                 set_bit(R5_LOCKED, &dev->flags);
2322                                 set_bit(R5_Wantwrite, &dev->flags);
2323                         }
2324                         if (failed >= 1) {
2325                                 dev = &sh->dev[failed_num[0]];
2326                                 locked++;
2327                                 set_bit(R5_LOCKED, &dev->flags);
2328                                 set_bit(R5_Wantwrite, &dev->flags);
2329                         }
2330
2331                         if (update_p) {
2332                                 dev = &sh->dev[pd_idx];
2333                                 locked ++;
2334                                 set_bit(R5_LOCKED, &dev->flags);
2335                                 set_bit(R5_Wantwrite, &dev->flags);
2336                         }
2337                         if (update_q) {
2338                                 dev = &sh->dev[qd_idx];
2339                                 locked++;
2340                                 set_bit(R5_LOCKED, &dev->flags);
2341                                 set_bit(R5_Wantwrite, &dev->flags);
2342                         }
2343                         clear_bit(STRIPE_DEGRADED, &sh->state);
2344
2345                         set_bit(STRIPE_INSYNC, &sh->state);
2346                 }
2347         }
2348
2349         if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2350                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2351                 clear_bit(STRIPE_SYNCING, &sh->state);
2352         }
2353
2354         /* If the failed drives are just a ReadError, then we might need
2355          * to progress the repair/check process
2356          */
2357         if (failed <= 2 && ! conf->mddev->ro)
2358                 for (i=0; i<failed;i++) {
2359                         dev = &sh->dev[failed_num[i]];
2360                         if (test_bit(R5_ReadError, &dev->flags)
2361                             && !test_bit(R5_LOCKED, &dev->flags)
2362                             && test_bit(R5_UPTODATE, &dev->flags)
2363                                 ) {
2364                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
2365                                         set_bit(R5_Wantwrite, &dev->flags);
2366                                         set_bit(R5_ReWrite, &dev->flags);
2367                                         set_bit(R5_LOCKED, &dev->flags);
2368                                 } else {
2369                                         /* let's read it back */
2370                                         set_bit(R5_Wantread, &dev->flags);
2371                                         set_bit(R5_LOCKED, &dev->flags);
2372                                 }
2373                         }
2374                 }
2375         spin_unlock(&sh->lock);
2376
2377         while ((bi=return_bi)) {
2378                 int bytes = bi->bi_size;
2379
2380                 return_bi = bi->bi_next;
2381                 bi->bi_next = NULL;
2382                 bi->bi_size = 0;
2383                 bi->bi_end_io(bi, bytes, 0);
2384         }
2385         for (i=disks; i-- ;) {
2386                 int rw;
2387                 struct bio *bi;
2388                 mdk_rdev_t *rdev;
2389                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
2390                         rw = 1;
2391                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
2392                         rw = 0;
2393                 else
2394                         continue;
2395
2396                 bi = &sh->dev[i].req;
2397
2398                 bi->bi_rw = rw;
2399                 if (rw)
2400                         bi->bi_end_io = raid5_end_write_request;
2401                 else
2402                         bi->bi_end_io = raid5_end_read_request;
2403
2404                 rcu_read_lock();
2405                 rdev = rcu_dereference(conf->disks[i].rdev);
2406                 if (rdev && test_bit(Faulty, &rdev->flags))
2407                         rdev = NULL;
2408                 if (rdev)
2409                         atomic_inc(&rdev->nr_pending);
2410                 rcu_read_unlock();
2411
2412                 if (rdev) {
2413                         if (syncing)
2414                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
2415
2416                         bi->bi_bdev = rdev->bdev;
2417                         PRINTK("for %llu schedule op %ld on disc %d\n",
2418                                 (unsigned long long)sh->sector, bi->bi_rw, i);
2419                         atomic_inc(&sh->count);
2420                         bi->bi_sector = sh->sector + rdev->data_offset;
2421                         bi->bi_flags = 1 << BIO_UPTODATE;
2422                         bi->bi_vcnt = 1;
2423                         bi->bi_max_vecs = 1;
2424                         bi->bi_idx = 0;
2425                         bi->bi_io_vec = &sh->dev[i].vec;
2426                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
2427                         bi->bi_io_vec[0].bv_offset = 0;
2428                         bi->bi_size = STRIPE_SIZE;
2429                         bi->bi_next = NULL;
2430                         if (rw == WRITE &&
2431                             test_bit(R5_ReWrite, &sh->dev[i].flags))
2432                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2433                         generic_make_request(bi);
2434                 } else {
2435                         if (rw == 1)
2436                                 set_bit(STRIPE_DEGRADED, &sh->state);
2437                         PRINTK("skip op %ld on disc %d for sector %llu\n",
2438                                 bi->bi_rw, i, (unsigned long long)sh->sector);
2439                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
2440                         set_bit(STRIPE_HANDLE, &sh->state);
2441                 }
2442         }
2443 }
2444
2445 static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
2446 {
2447         if (sh->raid_conf->level == 6)
2448                 handle_stripe6(sh, tmp_page);
2449         else
2450                 handle_stripe5(sh);
2451 }
2452
2453
2454
2455 static void raid5_activate_delayed(raid5_conf_t *conf)
2456 {
2457         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
2458                 while (!list_empty(&conf->delayed_list)) {
2459                         struct list_head *l = conf->delayed_list.next;
2460                         struct stripe_head *sh;
2461                         sh = list_entry(l, struct stripe_head, lru);
2462                         list_del_init(l);
2463                         clear_bit(STRIPE_DELAYED, &sh->state);
2464                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
2465                                 atomic_inc(&conf->preread_active_stripes);
2466                         list_add_tail(&sh->lru, &conf->handle_list);
2467                 }
2468         }
2469 }
2470
2471 static void activate_bit_delay(raid5_conf_t *conf)
2472 {
2473         /* device_lock is held */
2474         struct list_head head;
2475         list_add(&head, &conf->bitmap_list);
2476         list_del_init(&conf->bitmap_list);
2477         while (!list_empty(&head)) {
2478                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
2479                 list_del_init(&sh->lru);
2480                 atomic_inc(&sh->count);
2481                 __release_stripe(conf, sh);
2482         }
2483 }
2484
2485 static void unplug_slaves(mddev_t *mddev)
2486 {
2487         raid5_conf_t *conf = mddev_to_conf(mddev);
2488         int i;
2489
2490         rcu_read_lock();
2491         for (i=0; i<mddev->raid_disks; i++) {
2492                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
2493                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
2494                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
2495
2496                         atomic_inc(&rdev->nr_pending);
2497                         rcu_read_unlock();
2498
2499                         if (r_queue->unplug_fn)
2500                                 r_queue->unplug_fn(r_queue);
2501
2502                         rdev_dec_pending(rdev, mddev);
2503                         rcu_read_lock();
2504                 }
2505         }
2506         rcu_read_unlock();
2507 }
2508
2509 static void raid5_unplug_device(request_queue_t *q)
2510 {
2511         mddev_t *mddev = q->queuedata;
2512         raid5_conf_t *conf = mddev_to_conf(mddev);
2513         unsigned long flags;
2514
2515         spin_lock_irqsave(&conf->device_lock, flags);
2516
2517         if (blk_remove_plug(q)) {
2518                 conf->seq_flush++;
2519                 raid5_activate_delayed(conf);
2520         }
2521         md_wakeup_thread(mddev->thread);
2522
2523         spin_unlock_irqrestore(&conf->device_lock, flags);
2524
2525         unplug_slaves(mddev);
2526 }
2527
2528 static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk,
2529                              sector_t *error_sector)
2530 {
2531         mddev_t *mddev = q->queuedata;
2532         raid5_conf_t *conf = mddev_to_conf(mddev);
2533         int i, ret = 0;
2534
2535         rcu_read_lock();
2536         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
2537                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
2538                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
2539                         struct block_device *bdev = rdev->bdev;
2540                         request_queue_t *r_queue = bdev_get_queue(bdev);
2541
2542                         if (!r_queue->issue_flush_fn)
2543                                 ret = -EOPNOTSUPP;
2544                         else {
2545                                 atomic_inc(&rdev->nr_pending);
2546                                 rcu_read_unlock();
2547                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
2548                                                               error_sector);
2549                                 rdev_dec_pending(rdev, mddev);
2550                                 rcu_read_lock();
2551                         }
2552                 }
2553         }
2554         rcu_read_unlock();
2555         return ret;
2556 }
2557
2558 static inline void raid5_plug_device(raid5_conf_t *conf)
2559 {
2560         spin_lock_irq(&conf->device_lock);
2561         blk_plug_device(conf->mddev->queue);
2562         spin_unlock_irq(&conf->device_lock);
2563 }
2564
2565 static int make_request(request_queue_t *q, struct bio * bi)
2566 {
2567         mddev_t *mddev = q->queuedata;
2568         raid5_conf_t *conf = mddev_to_conf(mddev);
2569         unsigned int dd_idx, pd_idx;
2570         sector_t new_sector;
2571         sector_t logical_sector, last_sector;
2572         struct stripe_head *sh;
2573         const int rw = bio_data_dir(bi);
2574         int remaining;
2575
2576         if (unlikely(bio_barrier(bi))) {
2577                 bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
2578                 return 0;
2579         }
2580
2581         md_write_start(mddev, bi);
2582
2583         disk_stat_inc(mddev->gendisk, ios[rw]);
2584         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
2585
2586         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
2587         last_sector = bi->bi_sector + (bi->bi_size>>9);
2588         bi->bi_next = NULL;
2589         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
2590
2591         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
2592                 DEFINE_WAIT(w);
2593                 int disks, data_disks;
2594
2595         retry:
2596                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
2597                 if (likely(conf->expand_progress == MaxSector))
2598                         disks = conf->raid_disks;
2599                 else {
2600                         /* spinlock is needed as expand_progress may be
2601                          * 64bit on a 32bit platform, and so it might be
2602                          * possible to see a half-updated value
2603                          * Ofcourse expand_progress could change after
2604                          * the lock is dropped, so once we get a reference
2605                          * to the stripe that we think it is, we will have
2606                          * to check again.
2607                          */
2608                         spin_lock_irq(&conf->device_lock);
2609                         disks = conf->raid_disks;
2610                         if (logical_sector >= conf->expand_progress)
2611                                 disks = conf->previous_raid_disks;
2612                         else {
2613                                 if (logical_sector >= conf->expand_lo) {
2614                                         spin_unlock_irq(&conf->device_lock);
2615                                         schedule();
2616                                         goto retry;
2617                                 }
2618                         }
2619                         spin_unlock_irq(&conf->device_lock);
2620                 }
2621                 data_disks = disks - conf->max_degraded;
2622
2623                 new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
2624                                                   &dd_idx, &pd_idx, conf);
2625                 PRINTK("raid5: make_request, sector %llu logical %llu\n",
2626                         (unsigned long long)new_sector,
2627                         (unsigned long long)logical_sector);
2628
2629                 sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
2630                 if (sh) {
2631                         if (unlikely(conf->expand_progress != MaxSector)) {
2632                                 /* expansion might have moved on while waiting for a
2633                                  * stripe, so we must do the range check again.
2634                                  * Expansion could still move past after this
2635                                  * test, but as we are holding a reference to
2636                                  * 'sh', we know that if that happens,
2637                                  *  STRIPE_EXPANDING will get set and the expansion
2638                                  * won't proceed until we finish with the stripe.
2639                                  */
2640                                 int must_retry = 0;
2641                                 spin_lock_irq(&conf->device_lock);
2642                                 if (logical_sector <  conf->expand_progress &&
2643                                     disks == conf->previous_raid_disks)
2644                                         /* mismatch, need to try again */
2645                                         must_retry = 1;
2646                                 spin_unlock_irq(&conf->device_lock);
2647                                 if (must_retry) {
2648                                         release_stripe(sh);
2649                                         goto retry;
2650                                 }
2651                         }
2652                         /* FIXME what if we get a false positive because these
2653                          * are being updated.
2654                          */
2655                         if (logical_sector >= mddev->suspend_lo &&
2656                             logical_sector < mddev->suspend_hi) {
2657                                 release_stripe(sh);
2658                                 schedule();
2659                                 goto retry;
2660                         }
2661
2662                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
2663                             !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
2664                                 /* Stripe is busy expanding or
2665                                  * add failed due to overlap.  Flush everything
2666                                  * and wait a while
2667                                  */
2668                                 raid5_unplug_device(mddev->queue);
2669                                 release_stripe(sh);
2670                                 schedule();
2671                                 goto retry;
2672                         }
2673                         finish_wait(&conf->wait_for_overlap, &w);
2674                         raid5_plug_device(conf);
2675                         handle_stripe(sh, NULL);
2676                         release_stripe(sh);
2677                 } else {
2678                         /* cannot get stripe for read-ahead, just give-up */
2679                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2680                         finish_wait(&conf->wait_for_overlap, &w);
2681                         break;
2682                 }
2683
2684         }
2685         spin_lock_irq(&conf->device_lock);
2686         remaining = --bi->bi_phys_segments;
2687         spin_unlock_irq(&conf->device_lock);
2688         if (remaining == 0) {
2689                 int bytes = bi->bi_size;
2690
2691                 if ( rw == WRITE )
2692                         md_write_end(mddev);
2693                 bi->bi_size = 0;
2694                 bi->bi_end_io(bi, bytes, 0);
2695         }
2696         return 0;
2697 }
2698
2699 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
2700 {
2701         /* reshaping is quite different to recovery/resync so it is
2702          * handled quite separately ... here.
2703          *
2704          * On each call to sync_request, we gather one chunk worth of
2705          * destination stripes and flag them as expanding.
2706          * Then we find all the source stripes and request reads.
2707          * As the reads complete, handle_stripe will copy the data
2708          * into the destination stripe and release that stripe.
2709          */
2710         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
2711         struct stripe_head *sh;
2712         int pd_idx;
2713         sector_t first_sector, last_sector;
2714         int raid_disks;
2715         int data_disks;
2716         int i;
2717         int dd_idx;
2718         sector_t writepos, safepos, gap;
2719
2720         if (sector_nr == 0 &&
2721             conf->expand_progress != 0) {
2722                 /* restarting in the middle, skip the initial sectors */
2723                 sector_nr = conf->expand_progress;
2724                 sector_div(sector_nr, conf->raid_disks-1);
2725                 *skipped = 1;
2726                 return sector_nr;
2727         }
2728
2729         /* we update the metadata when there is more than 3Meg
2730          * in the block range (that is rather arbitrary, should
2731          * probably be time based) or when the data about to be
2732          * copied would over-write the source of the data at
2733          * the front of the range.
2734          * i.e. one new_stripe forward from expand_progress new_maps
2735          * to after where expand_lo old_maps to
2736          */
2737         writepos = conf->expand_progress +
2738                 conf->chunk_size/512*(conf->raid_disks-1);
2739         sector_div(writepos, conf->raid_disks-1);
2740         safepos = conf->expand_lo;
2741         sector_div(safepos, conf->previous_raid_disks-1);
2742         gap = conf->expand_progress - conf->expand_lo;
2743
2744         if (writepos >= safepos ||
2745             gap > (conf->raid_disks-1)*3000*2 /*3Meg*/) {
2746                 /* Cannot proceed until we've updated the superblock... */
2747                 wait_event(conf->wait_for_overlap,
2748                            atomic_read(&conf->reshape_stripes)==0);
2749                 mddev->reshape_position = conf->expand_progress;
2750                 mddev->sb_dirty = 1;
2751                 md_wakeup_thread(mddev->thread);
2752                 wait_event(mddev->sb_wait, mddev->sb_dirty == 0 ||
2753                            kthread_should_stop());
2754                 spin_lock_irq(&conf->device_lock);
2755                 conf->expand_lo = mddev->reshape_position;
2756                 spin_unlock_irq(&conf->device_lock);
2757                 wake_up(&conf->wait_for_overlap);
2758         }
2759
2760         for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
2761                 int j;
2762                 int skipped = 0;
2763                 pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
2764                 sh = get_active_stripe(conf, sector_nr+i,
2765                                        conf->raid_disks, pd_idx, 0);
2766                 set_bit(STRIPE_EXPANDING, &sh->state);
2767                 atomic_inc(&conf->reshape_stripes);
2768                 /* If any of this stripe is beyond the end of the old
2769                  * array, then we need to zero those blocks
2770                  */
2771                 for (j=sh->disks; j--;) {
2772                         sector_t s;
2773                         if (j == sh->pd_idx)
2774                                 continue;
2775                         s = compute_blocknr(sh, j);
2776                         if (s < (mddev->array_size<<1)) {
2777                                 skipped = 1;
2778                                 continue;
2779                         }
2780                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
2781                         set_bit(R5_Expanded, &sh->dev[j].flags);
2782                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
2783                 }
2784                 if (!skipped) {
2785                         set_bit(STRIPE_EXPAND_READY, &sh->state);
2786                         set_bit(STRIPE_HANDLE, &sh->state);
2787                 }
2788                 release_stripe(sh);
2789         }
2790         spin_lock_irq(&conf->device_lock);
2791         conf->expand_progress = (sector_nr + i)*(conf->raid_disks-1);
2792         spin_unlock_irq(&conf->device_lock);
2793         /* Ok, those stripe are ready. We can start scheduling
2794          * reads on the source stripes.
2795          * The source stripes are determined by mapping the first and last
2796          * block on the destination stripes.
2797          */
2798         raid_disks = conf->previous_raid_disks;
2799         data_disks = raid_disks - 1;
2800         first_sector =
2801                 raid5_compute_sector(sector_nr*(conf->raid_disks-1),
2802                                      raid_disks, data_disks,
2803                                      &dd_idx, &pd_idx, conf);
2804         last_sector =
2805                 raid5_compute_sector((sector_nr+conf->chunk_size/512)
2806                                      *(conf->raid_disks-1) -1,
2807                                      raid_disks, data_disks,
2808                                      &dd_idx, &pd_idx, conf);
2809         if (last_sector >= (mddev->size<<1))
2810                 last_sector = (mddev->size<<1)-1;
2811         while (first_sector <= last_sector) {
2812                 pd_idx = stripe_to_pdidx(first_sector, conf, conf->previous_raid_disks);
2813                 sh = get_active_stripe(conf, first_sector,
2814                                        conf->previous_raid_disks, pd_idx, 0);
2815                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2816                 set_bit(STRIPE_HANDLE, &sh->state);
2817                 release_stripe(sh);
2818                 first_sector += STRIPE_SECTORS;
2819         }
2820         return conf->chunk_size>>9;
2821 }
2822
2823 /* FIXME go_faster isn't used */
2824 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
2825 {
2826         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
2827         struct stripe_head *sh;
2828         int pd_idx;
2829         int raid_disks = conf->raid_disks;
2830         sector_t max_sector = mddev->size << 1;
2831         int sync_blocks;
2832         int still_degraded = 0;
2833         int i;
2834
2835         if (sector_nr >= max_sector) {
2836                 /* just being told to finish up .. nothing much to do */
2837                 unplug_slaves(mddev);
2838                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
2839                         end_reshape(conf);
2840                         return 0;
2841                 }
2842
2843                 if (mddev->curr_resync < max_sector) /* aborted */
2844                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2845                                         &sync_blocks, 1);
2846                 else /* completed sync */
2847                         conf->fullsync = 0;
2848                 bitmap_close_sync(mddev->bitmap);
2849
2850                 return 0;
2851         }
2852
2853         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
2854                 return reshape_request(mddev, sector_nr, skipped);
2855
2856         /* if there is too many failed drives and we are trying
2857          * to resync, then assert that we are finished, because there is
2858          * nothing we can do.
2859          */
2860         if (mddev->degraded >= conf->max_degraded &&
2861             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
2862                 sector_t rv = (mddev->size << 1) - sector_nr;
2863                 *skipped = 1;
2864                 return rv;
2865         }
2866         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
2867             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
2868             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
2869                 /* we can skip this block, and probably more */
2870                 sync_blocks /= STRIPE_SECTORS;
2871                 *skipped = 1;
2872                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
2873         }
2874
2875         pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
2876         sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
2877         if (sh == NULL) {
2878                 sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
2879                 /* make sure we don't swamp the stripe cache if someone else
2880                  * is trying to get access
2881                  */
2882                 schedule_timeout_uninterruptible(1);
2883         }
2884         /* Need to check if array will still be degraded after recovery/resync
2885          * We don't need to check the 'failed' flag as when that gets set,
2886          * recovery aborts.
2887          */
2888         for (i=0; i<mddev->raid_disks; i++)
2889                 if (conf->disks[i].rdev == NULL)
2890                         still_degraded = 1;
2891
2892         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
2893
2894         spin_lock(&sh->lock);
2895         set_bit(STRIPE_SYNCING, &sh->state);
2896         clear_bit(STRIPE_INSYNC, &sh->state);
2897         spin_unlock(&sh->lock);
2898
2899         handle_stripe(sh, NULL);
2900         release_stripe(sh);
2901
2902         return STRIPE_SECTORS;
2903 }
2904
2905 /*
2906  * This is our raid5 kernel thread.
2907  *
2908  * We scan the hash table for stripes which can be handled now.
2909  * During the scan, completed stripes are saved for us by the interrupt
2910  * handler, so that they will not have to wait for our next wakeup.
2911  */
2912 static void raid5d (mddev_t *mddev)
2913 {
2914         struct stripe_head *sh;
2915         raid5_conf_t *conf = mddev_to_conf(mddev);
2916         int handled;
2917
2918         PRINTK("+++ raid5d active\n");
2919
2920         md_check_recovery(mddev);
2921
2922         handled = 0;
2923         spin_lock_irq(&conf->device_lock);
2924         while (1) {
2925                 struct list_head *first;
2926
2927                 if (conf->seq_flush - conf->seq_write > 0) {
2928                         int seq = conf->seq_flush;
2929                         spin_unlock_irq(&conf->device_lock);
2930                         bitmap_unplug(mddev->bitmap);
2931                         spin_lock_irq(&conf->device_lock);
2932                         conf->seq_write = seq;
2933                         activate_bit_delay(conf);
2934                 }
2935
2936                 if (list_empty(&conf->handle_list) &&
2937                     atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
2938                     !blk_queue_plugged(mddev->queue) &&
2939                     !list_empty(&conf->delayed_list))
2940                         raid5_activate_delayed(conf);
2941
2942                 if (list_empty(&conf->handle_list))
2943                         break;
2944
2945                 first = conf->handle_list.next;
2946                 sh = list_entry(first, struct stripe_head, lru);
2947
2948                 list_del_init(first);
2949                 atomic_inc(&sh->count);
2950                 BUG_ON(atomic_read(&sh->count)!= 1);
2951                 spin_unlock_irq(&conf->device_lock);
2952
2953                 handled++;
2954                 handle_stripe(sh, conf->spare_page);
2955                 release_stripe(sh);
2956
2957                 spin_lock_irq(&conf->device_lock);
2958         }
2959         PRINTK("%d stripes handled\n", handled);
2960
2961         spin_unlock_irq(&conf->device_lock);
2962
2963         unplug_slaves(mddev);
2964
2965         PRINTK("--- raid5d inactive\n");
2966 }
2967
2968 static ssize_t
2969 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
2970 {
2971         raid5_conf_t *conf = mddev_to_conf(mddev);
2972         if (conf)
2973                 return sprintf(page, "%d\n", conf->max_nr_stripes);
2974         else
2975                 return 0;
2976 }
2977
2978 static ssize_t
2979 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
2980 {
2981         raid5_conf_t *conf = mddev_to_conf(mddev);
2982         char *end;
2983         int new;
2984         if (len >= PAGE_SIZE)
2985                 return -EINVAL;
2986         if (!conf)
2987                 return -ENODEV;
2988
2989         new = simple_strtoul(page, &end, 10);
2990         if (!*page || (*end && *end != '\n') )
2991                 return -EINVAL;
2992         if (new <= 16 || new > 32768)
2993                 return -EINVAL;
2994         while (new < conf->max_nr_stripes) {
2995                 if (drop_one_stripe(conf))
2996                         conf->max_nr_stripes--;
2997                 else
2998                         break;
2999         }
3000         while (new > conf->max_nr_stripes) {
3001                 if (grow_one_stripe(conf))
3002                         conf->max_nr_stripes++;
3003                 else break;
3004         }
3005         return len;
3006 }
3007
3008 static struct md_sysfs_entry
3009 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
3010                                 raid5_show_stripe_cache_size,
3011                                 raid5_store_stripe_cache_size);
3012
3013 static ssize_t
3014 stripe_cache_active_show(mddev_t *mddev, char *page)
3015 {
3016         raid5_conf_t *conf = mddev_to_conf(mddev);
3017         if (conf)
3018                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
3019         else
3020                 return 0;
3021 }
3022
3023 static struct md_sysfs_entry
3024 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
3025
3026 static struct attribute *raid5_attrs[] =  {
3027         &raid5_stripecache_size.attr,
3028         &raid5_stripecache_active.attr,
3029         NULL,
3030 };
3031 static struct attribute_group raid5_attrs_group = {
3032         .name = NULL,
3033         .attrs = raid5_attrs,
3034 };
3035
3036 static int run(mddev_t *mddev)
3037 {
3038         raid5_conf_t *conf;
3039         int raid_disk, memory;
3040         mdk_rdev_t *rdev;
3041         struct disk_info *disk;
3042         struct list_head *tmp;
3043
3044         if (mddev->level != 5 && mddev->level != 4 && mddev->level != 6) {
3045                 printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
3046                        mdname(mddev), mddev->level);
3047                 return -EIO;
3048         }
3049
3050         if (mddev->reshape_position != MaxSector) {
3051                 /* Check that we can continue the reshape.
3052                  * Currently only disks can change, it must
3053                  * increase, and we must be past the point where
3054                  * a stripe over-writes itself
3055                  */
3056                 sector_t here_new, here_old;
3057                 int old_disks;
3058
3059                 if (mddev->new_level != mddev->level ||
3060                     mddev->new_layout != mddev->layout ||
3061                     mddev->new_chunk != mddev->chunk_size) {
3062                         printk(KERN_ERR "raid5: %s: unsupported reshape required - aborting.\n",
3063                                mdname(mddev));
3064                         return -EINVAL;
3065                 }
3066                 if (mddev->delta_disks <= 0) {
3067                         printk(KERN_ERR "raid5: %s: unsupported reshape (reduce disks) required - aborting.\n",
3068                                mdname(mddev));
3069                         return -EINVAL;
3070                 }
3071                 old_disks = mddev->raid_disks - mddev->delta_disks;
3072                 /* reshape_position must be on a new-stripe boundary, and one
3073                  * further up in new geometry must map after here in old geometry.
3074                  */
3075                 here_new = mddev->reshape_position;
3076                 if (sector_div(here_new, (mddev->chunk_size>>9)*(mddev->raid_disks-1))) {
3077                         printk(KERN_ERR "raid5: reshape_position not on a stripe boundary\n");
3078                         return -EINVAL;
3079                 }
3080                 /* here_new is the stripe we will write to */
3081                 here_old = mddev->reshape_position;
3082                 sector_div(here_old, (mddev->chunk_size>>9)*(old_disks-1));
3083                 /* here_old is the first stripe that we might need to read from */
3084                 if (here_new >= here_old) {
3085                         /* Reading from the same stripe as writing to - bad */
3086                         printk(KERN_ERR "raid5: reshape_position too early for auto-recovery - aborting.\n");
3087                         return -EINVAL;
3088                 }
3089                 printk(KERN_INFO "raid5: reshape will continue\n");
3090                 /* OK, we should be able to continue; */
3091         }
3092
3093
3094         mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
3095         if ((conf = mddev->private) == NULL)
3096                 goto abort;
3097         if (mddev->reshape_position == MaxSector) {
3098                 conf->previous_raid_disks = conf->raid_disks = mddev->raid_disks;
3099         } else {
3100                 conf->raid_disks = mddev->raid_disks;
3101                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
3102         }
3103
3104         conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
3105                               GFP_KERNEL);
3106         if (!conf->disks)
3107                 goto abort;
3108
3109         conf->mddev = mddev;
3110
3111         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
3112                 goto abort;
3113
3114         if (mddev->level == 6) {
3115                 conf->spare_page = alloc_page(GFP_KERNEL);
3116                 if (!conf->spare_page)
3117                         goto abort;
3118         }
3119         spin_lock_init(&conf->device_lock);
3120         init_waitqueue_head(&conf->wait_for_stripe);
3121         init_waitqueue_head(&conf->wait_for_overlap);
3122         INIT_LIST_HEAD(&conf->handle_list);
3123         INIT_LIST_HEAD(&conf->delayed_list);
3124         INIT_LIST_HEAD(&conf->bitmap_list);
3125         INIT_LIST_HEAD(&conf->inactive_list);
3126         atomic_set(&conf->active_stripes, 0);
3127         atomic_set(&conf->preread_active_stripes, 0);
3128
3129         PRINTK("raid5: run(%s) called.\n", mdname(mddev));
3130
3131         ITERATE_RDEV(mddev,rdev,tmp) {
3132                 raid_disk = rdev->raid_disk;
3133                 if (raid_disk >= conf->raid_disks
3134                     || raid_disk < 0)
3135                         continue;
3136                 disk = conf->disks + raid_disk;
3137
3138                 disk->rdev = rdev;
3139
3140                 if (test_bit(In_sync, &rdev->flags)) {
3141                         char b[BDEVNAME_SIZE];
3142                         printk(KERN_INFO "raid5: device %s operational as raid"
3143                                 " disk %d\n", bdevname(rdev->bdev,b),
3144                                 raid_disk);
3145                         conf->working_disks++;
3146                 }
3147         }
3148
3149         /*
3150          * 0 for a fully functional array, 1 or 2 for a degraded array.
3151          */
3152         mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks;
3153         conf->mddev = mddev;
3154         conf->chunk_size = mddev->chunk_size;
3155         conf->level = mddev->level;
3156         if (conf->level == 6)
3157                 conf->max_degraded = 2;
3158         else
3159                 conf->max_degraded = 1;
3160         conf->algorithm = mddev->layout;
3161         conf->max_nr_stripes = NR_STRIPES;
3162         conf->expand_progress = mddev->reshape_position;
3163
3164         /* device size must be a multiple of chunk size */
3165         mddev->size &= ~(mddev->chunk_size/1024 -1);
3166         mddev->resync_max_sectors = mddev->size << 1;
3167
3168         if (conf->level == 6 && conf->raid_disks < 4) {
3169                 printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
3170                        mdname(mddev), conf->raid_disks);
3171                 goto abort;
3172         }
3173         if (!conf->chunk_size || conf->chunk_size % 4) {
3174                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
3175                         conf->chunk_size, mdname(mddev));
3176                 goto abort;
3177         }
3178         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
3179                 printk(KERN_ERR
3180                         "raid5: unsupported parity algorithm %d for %s\n",
3181                         conf->algorithm, mdname(mddev));
3182                 goto abort;
3183         }
3184         if (mddev->degraded > conf->max_degraded) {
3185                 printk(KERN_ERR "raid5: not enough operational devices for %s"
3186                         " (%d/%d failed)\n",
3187                         mdname(mddev), conf->failed_disks, conf->raid_disks);
3188                 goto abort;
3189         }
3190
3191         if (mddev->degraded > 0 &&
3192             mddev->recovery_cp != MaxSector) {
3193                 if (mddev->ok_start_degraded)
3194                         printk(KERN_WARNING
3195                                "raid5: starting dirty degraded array: %s"
3196                                "- data corruption possible.\n",
3197                                mdname(mddev));
3198                 else {
3199                         printk(KERN_ERR
3200                                "raid5: cannot start dirty degraded array for %s\n",
3201                                mdname(mddev));
3202                         goto abort;
3203                 }
3204         }
3205
3206         {
3207                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
3208                 if (!mddev->thread) {
3209                         printk(KERN_ERR
3210                                 "raid5: couldn't allocate thread for %s\n",
3211                                 mdname(mddev));
3212                         goto abort;
3213                 }
3214         }
3215         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
3216                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
3217         if (grow_stripes(conf, conf->max_nr_stripes)) {
3218                 printk(KERN_ERR
3219                         "raid5: couldn't allocate %dkB for buffers\n", memory);
3220                 shrink_stripes(conf);
3221                 md_unregister_thread(mddev->thread);
3222                 goto abort;
3223         } else
3224                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
3225                         memory, mdname(mddev));
3226
3227         if (mddev->degraded == 0)
3228                 printk("raid5: raid level %d set %s active with %d out of %d"
3229                         " devices, algorithm %d\n", conf->level, mdname(mddev),
3230                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
3231                         conf->algorithm);
3232         else
3233                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
3234                         " out of %d devices, algorithm %d\n", conf->level,
3235                         mdname(mddev), mddev->raid_disks - mddev->degraded,
3236                         mddev->raid_disks, conf->algorithm);
3237
3238         print_raid5_conf(conf);
3239
3240         if (conf->expand_progress != MaxSector) {
3241                 printk("...ok start reshape thread\n");
3242                 conf->expand_lo = conf->expand_progress;
3243                 atomic_set(&conf->reshape_stripes, 0);
3244                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
3245                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
3246                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
3247                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
3248                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
3249                                                         "%s_reshape");
3250                 /* FIXME if md_register_thread fails?? */
3251                 md_wakeup_thread(mddev->sync_thread);
3252
3253         }
3254
3255         /* read-ahead size must cover two whole stripes, which is
3256          * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
3257          */
3258         {
3259                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
3260                 int stripe = data_disks *
3261                         (mddev->chunk_size / PAGE_SIZE);
3262                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
3263                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
3264         }
3265
3266         /* Ok, everything is just fine now */
3267         sysfs_create_group(&mddev->kobj, &raid5_attrs_group);
3268
3269         mddev->queue->unplug_fn = raid5_unplug_device;
3270         mddev->queue->issue_flush_fn = raid5_issue_flush;
3271         mddev->array_size =  mddev->size * (conf->previous_raid_disks -
3272                                             conf->max_degraded);
3273
3274         return 0;
3275 abort:
3276         if (conf) {
3277                 print_raid5_conf(conf);
3278                 safe_put_page(conf->spare_page);
3279                 kfree(conf->disks);
3280                 kfree(conf->stripe_hashtbl);
3281                 kfree(conf);
3282         }
3283         mddev->private = NULL;
3284         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
3285         return -EIO;
3286 }
3287
3288
3289
3290 static int stop(mddev_t *mddev)
3291 {
3292         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3293
3294         md_unregister_thread(mddev->thread);
3295         mddev->thread = NULL;
3296         shrink_stripes(conf);
3297         kfree(conf->stripe_hashtbl);
3298         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
3299         sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
3300         kfree(conf->disks);
3301         kfree(conf);
3302         mddev->private = NULL;
3303         return 0;
3304 }
3305
3306 #if RAID5_DEBUG
3307 static void print_sh (struct seq_file *seq, struct stripe_head *sh)
3308 {
3309         int i;
3310
3311         seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
3312                    (unsigned long long)sh->sector, sh->pd_idx, sh->state);
3313         seq_printf(seq, "sh %llu,  count %d.\n",
3314                    (unsigned long long)sh->sector, atomic_read(&sh->count));
3315         seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
3316         for (i = 0; i < sh->disks; i++) {
3317                 seq_printf(seq, "(cache%d: %p %ld) ",
3318                            i, sh->dev[i].page, sh->dev[i].flags);
3319         }
3320         seq_printf(seq, "\n");
3321 }
3322
3323 static void printall (struct seq_file *seq, raid5_conf_t *conf)
3324 {
3325         struct stripe_head *sh;
3326         struct hlist_node *hn;
3327         int i;
3328
3329         spin_lock_irq(&conf->device_lock);
3330         for (i = 0; i < NR_HASH; i++) {
3331                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
3332                         if (sh->raid_conf != conf)
3333                                 continue;
3334                         print_sh(seq, sh);
3335                 }
3336         }
3337         spin_unlock_irq(&conf->device_lock);
3338 }
3339 #endif
3340
3341 static void status (struct seq_file *seq, mddev_t *mddev)
3342 {
3343         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3344         int i;
3345
3346         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
3347         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->working_disks);
3348         for (i = 0; i < conf->raid_disks; i++)
3349                 seq_printf (seq, "%s",
3350                                conf->disks[i].rdev &&
3351                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
3352         seq_printf (seq, "]");
3353 #if RAID5_DEBUG
3354         seq_printf (seq, "\n");
3355         printall(seq, conf);
3356 #endif
3357 }
3358
3359 static void print_raid5_conf (raid5_conf_t *conf)
3360 {
3361         int i;
3362         struct disk_info *tmp;
3363
3364         printk("RAID5 conf printout:\n");
3365         if (!conf) {
3366                 printk("(conf==NULL)\n");
3367                 return;
3368         }
3369         printk(" --- rd:%d wd:%d fd:%d\n", conf->raid_disks,
3370                  conf->working_disks, conf->failed_disks);
3371
3372         for (i = 0; i < conf->raid_disks; i++) {
3373                 char b[BDEVNAME_SIZE];
3374                 tmp = conf->disks + i;
3375                 if (tmp->rdev)
3376                 printk(" disk %d, o:%d, dev:%s\n",
3377                         i, !test_bit(Faulty, &tmp->rdev->flags),
3378                         bdevname(tmp->rdev->bdev,b));
3379         }
3380 }
3381
3382 static int raid5_spare_active(mddev_t *mddev)
3383 {
3384         int i;
3385         raid5_conf_t *conf = mddev->private;
3386         struct disk_info *tmp;
3387
3388         for (i = 0; i < conf->raid_disks; i++) {
3389                 tmp = conf->disks + i;
3390                 if (tmp->rdev
3391                     && !test_bit(Faulty, &tmp->rdev->flags)
3392                     && !test_bit(In_sync, &tmp->rdev->flags)) {
3393                         mddev->degraded--;
3394                         conf->failed_disks--;
3395                         conf->working_disks++;
3396                         set_bit(In_sync, &tmp->rdev->flags);
3397                 }
3398         }
3399         print_raid5_conf(conf);
3400         return 0;
3401 }
3402
3403 static int raid5_remove_disk(mddev_t *mddev, int number)
3404 {
3405         raid5_conf_t *conf = mddev->private;
3406         int err = 0;
3407         mdk_rdev_t *rdev;
3408         struct disk_info *p = conf->disks + number;
3409
3410         print_raid5_conf(conf);
3411         rdev = p->rdev;
3412         if (rdev) {
3413                 if (test_bit(In_sync, &rdev->flags) ||
3414                     atomic_read(&rdev->nr_pending)) {
3415                         err = -EBUSY;
3416                         goto abort;
3417                 }
3418                 p->rdev = NULL;
3419                 synchronize_rcu();
3420                 if (atomic_read(&rdev->nr_pending)) {
3421                         /* lost the race, try later */
3422                         err = -EBUSY;
3423                         p->rdev = rdev;
3424                 }
3425         }
3426 abort:
3427
3428         print_raid5_conf(conf);
3429         return err;
3430 }
3431
3432 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
3433 {
3434         raid5_conf_t *conf = mddev->private;
3435         int found = 0;
3436         int disk;
3437         struct disk_info *p;
3438
3439         if (mddev->degraded > conf->max_degraded)
3440                 /* no point adding a device */
3441                 return 0;
3442
3443         /*
3444          * find the disk ... but prefer rdev->saved_raid_disk
3445          * if possible.
3446          */
3447         if (rdev->saved_raid_disk >= 0 &&
3448             conf->disks[rdev->saved_raid_disk].rdev == NULL)
3449                 disk = rdev->saved_raid_disk;
3450         else
3451                 disk = 0;
3452         for ( ; disk < conf->raid_disks; disk++)
3453                 if ((p=conf->disks + disk)->rdev == NULL) {
3454                         clear_bit(In_sync, &rdev->flags);
3455                         rdev->raid_disk = disk;
3456                         found = 1;
3457                         if (rdev->saved_raid_disk != disk)
3458                                 conf->fullsync = 1;
3459                         rcu_assign_pointer(p->rdev, rdev);
3460                         break;
3461                 }
3462         print_raid5_conf(conf);
3463         return found;
3464 }
3465
3466 static int raid5_resize(mddev_t *mddev, sector_t sectors)
3467 {
3468         /* no resync is happening, and there is enough space
3469          * on all devices, so we can resize.
3470          * We need to make sure resync covers any new space.
3471          * If the array is shrinking we should possibly wait until
3472          * any io in the removed space completes, but it hardly seems
3473          * worth it.
3474          */
3475         raid5_conf_t *conf = mddev_to_conf(mddev);
3476
3477         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
3478         mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
3479         set_capacity(mddev->gendisk, mddev->array_size << 1);
3480         mddev->changed = 1;
3481         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
3482                 mddev->recovery_cp = mddev->size << 1;
3483                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3484         }
3485         mddev->size = sectors /2;
3486         mddev->resync_max_sectors = sectors;
3487         return 0;
3488 }
3489
3490 #ifdef CONFIG_MD_RAID5_RESHAPE
3491 static int raid5_check_reshape(mddev_t *mddev)
3492 {
3493         raid5_conf_t *conf = mddev_to_conf(mddev);
3494         int err;
3495
3496         if (mddev->delta_disks < 0 ||
3497             mddev->new_level != mddev->level)
3498                 return -EINVAL; /* Cannot shrink array or change level yet */
3499         if (mddev->delta_disks == 0)
3500                 return 0; /* nothing to do */
3501
3502         /* Can only proceed if there are plenty of stripe_heads.
3503          * We need a minimum of one full stripe,, and for sensible progress
3504          * it is best to have about 4 times that.
3505          * If we require 4 times, then the default 256 4K stripe_heads will
3506          * allow for chunk sizes up to 256K, which is probably OK.
3507          * If the chunk size is greater, user-space should request more
3508          * stripe_heads first.
3509          */
3510         if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
3511             (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
3512                 printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
3513                        (mddev->chunk_size / STRIPE_SIZE)*4);
3514                 return -ENOSPC;
3515         }
3516
3517         err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
3518         if (err)
3519                 return err;
3520
3521         /* looks like we might be able to manage this */
3522         return 0;
3523 }
3524
3525 static int raid5_start_reshape(mddev_t *mddev)
3526 {
3527         raid5_conf_t *conf = mddev_to_conf(mddev);
3528         mdk_rdev_t *rdev;
3529         struct list_head *rtmp;
3530         int spares = 0;
3531         int added_devices = 0;
3532
3533         if (mddev->degraded ||
3534             test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
3535                 return -EBUSY;
3536
3537         ITERATE_RDEV(mddev, rdev, rtmp)
3538                 if (rdev->raid_disk < 0 &&
3539                     !test_bit(Faulty, &rdev->flags))
3540                         spares++;
3541
3542         if (spares < mddev->delta_disks-1)
3543                 /* Not enough devices even to make a degraded array
3544                  * of that size
3545                  */
3546                 return -EINVAL;
3547
3548         atomic_set(&conf->reshape_stripes, 0);
3549         spin_lock_irq(&conf->device_lock);
3550         conf->previous_raid_disks = conf->raid_disks;
3551         conf->raid_disks += mddev->delta_disks;
3552         conf->expand_progress = 0;
3553         conf->expand_lo = 0;
3554         spin_unlock_irq(&conf->device_lock);
3555
3556         /* Add some new drives, as many as will fit.
3557          * We know there are enough to make the newly sized array work.
3558          */
3559         ITERATE_RDEV(mddev, rdev, rtmp)
3560                 if (rdev->raid_disk < 0 &&
3561                     !test_bit(Faulty, &rdev->flags)) {
3562                         if (raid5_add_disk(mddev, rdev)) {
3563                                 char nm[20];
3564                                 set_bit(In_sync, &rdev->flags);
3565                                 conf->working_disks++;
3566                                 added_devices++;
3567                                 rdev->recovery_offset = 0;
3568                                 sprintf(nm, "rd%d", rdev->raid_disk);
3569                                 sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
3570                         } else
3571                                 break;
3572                 }
3573
3574         mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
3575         mddev->raid_disks = conf->raid_disks;
3576         mddev->reshape_position = 0;
3577         mddev->sb_dirty = 1;
3578
3579         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
3580         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
3581         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
3582         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
3583         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
3584                                                 "%s_reshape");
3585         if (!mddev->sync_thread) {
3586                 mddev->recovery = 0;
3587                 spin_lock_irq(&conf->device_lock);
3588                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
3589                 conf->expand_progress = MaxSector;
3590                 spin_unlock_irq(&conf->device_lock);
3591                 return -EAGAIN;
3592         }
3593         md_wakeup_thread(mddev->sync_thread);
3594         md_new_event(mddev);
3595         return 0;
3596 }
3597 #endif
3598
3599 static void end_reshape(raid5_conf_t *conf)
3600 {
3601         struct block_device *bdev;
3602
3603         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
3604                 conf->mddev->array_size = conf->mddev->size * (conf->raid_disks-1);
3605                 set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
3606                 conf->mddev->changed = 1;
3607
3608                 bdev = bdget_disk(conf->mddev->gendisk, 0);
3609                 if (bdev) {
3610                         mutex_lock(&bdev->bd_inode->i_mutex);
3611                         i_size_write(bdev->bd_inode, conf->mddev->array_size << 10);
3612                         mutex_unlock(&bdev->bd_inode->i_mutex);
3613                         bdput(bdev);
3614                 }
3615                 spin_lock_irq(&conf->device_lock);
3616                 conf->expand_progress = MaxSector;
3617                 spin_unlock_irq(&conf->device_lock);
3618                 conf->mddev->reshape_position = MaxSector;
3619
3620                 /* read-ahead size must cover two whole stripes, which is
3621                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
3622                  */
3623                 {
3624                         int data_disks = conf->previous_raid_disks - conf->max_degraded;
3625                         int stripe = data_disks *
3626                                 (conf->mddev->chunk_size / PAGE_SIZE);
3627                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
3628                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
3629                 }
3630         }
3631 }
3632
3633 static void raid5_quiesce(mddev_t *mddev, int state)
3634 {
3635         raid5_conf_t *conf = mddev_to_conf(mddev);
3636
3637         switch(state) {
3638         case 2: /* resume for a suspend */
3639                 wake_up(&conf->wait_for_overlap);
3640                 break;
3641
3642         case 1: /* stop all writes */
3643                 spin_lock_irq(&conf->device_lock);
3644                 conf->quiesce = 1;
3645                 wait_event_lock_irq(conf->wait_for_stripe,
3646                                     atomic_read(&conf->active_stripes) == 0,
3647                                     conf->device_lock, /* nothing */);
3648                 spin_unlock_irq(&conf->device_lock);
3649                 break;
3650
3651         case 0: /* re-enable writes */
3652                 spin_lock_irq(&conf->device_lock);
3653                 conf->quiesce = 0;
3654                 wake_up(&conf->wait_for_stripe);
3655                 wake_up(&conf->wait_for_overlap);
3656                 spin_unlock_irq(&conf->device_lock);
3657                 break;
3658         }
3659 }
3660
3661 static struct mdk_personality raid6_personality =
3662 {
3663         .name           = "raid6",
3664         .level          = 6,
3665         .owner          = THIS_MODULE,
3666         .make_request   = make_request,
3667         .run            = run,
3668         .stop           = stop,
3669         .status         = status,
3670         .error_handler  = error,
3671         .hot_add_disk   = raid5_add_disk,
3672         .hot_remove_disk= raid5_remove_disk,
3673         .spare_active   = raid5_spare_active,
3674         .sync_request   = sync_request,
3675         .resize         = raid5_resize,
3676         .quiesce        = raid5_quiesce,
3677 };
3678 static struct mdk_personality raid5_personality =
3679 {
3680         .name           = "raid5",
3681         .level          = 5,
3682         .owner          = THIS_MODULE,
3683         .make_request   = make_request,
3684         .run            = run,
3685         .stop           = stop,
3686         .status         = status,
3687         .error_handler  = error,
3688         .hot_add_disk   = raid5_add_disk,
3689         .hot_remove_disk= raid5_remove_disk,
3690         .spare_active   = raid5_spare_active,
3691         .sync_request   = sync_request,
3692         .resize         = raid5_resize,
3693 #ifdef CONFIG_MD_RAID5_RESHAPE
3694         .check_reshape  = raid5_check_reshape,
3695         .start_reshape  = raid5_start_reshape,
3696 #endif
3697         .quiesce        = raid5_quiesce,
3698 };
3699
3700 static struct mdk_personality raid4_personality =
3701 {
3702         .name           = "raid4",
3703         .level          = 4,
3704         .owner          = THIS_MODULE,
3705         .make_request   = make_request,
3706         .run            = run,
3707         .stop           = stop,
3708         .status         = status,
3709         .error_handler  = error,
3710         .hot_add_disk   = raid5_add_disk,
3711         .hot_remove_disk= raid5_remove_disk,
3712         .spare_active   = raid5_spare_active,
3713         .sync_request   = sync_request,
3714         .resize         = raid5_resize,
3715         .quiesce        = raid5_quiesce,
3716 };
3717
3718 static int __init raid5_init(void)
3719 {
3720         int e;
3721
3722         e = raid6_select_algo();
3723         if ( e )
3724                 return e;
3725         register_md_personality(&raid6_personality);
3726         register_md_personality(&raid5_personality);
3727         register_md_personality(&raid4_personality);
3728         return 0;
3729 }
3730
3731 static void raid5_exit(void)
3732 {
3733         unregister_md_personality(&raid6_personality);
3734         unregister_md_personality(&raid5_personality);
3735         unregister_md_personality(&raid4_personality);
3736 }
3737
3738 module_init(raid5_init);
3739 module_exit(raid5_exit);
3740 MODULE_LICENSE("GPL");
3741 MODULE_ALIAS("md-personality-4"); /* RAID5 */
3742 MODULE_ALIAS("md-raid5");
3743 MODULE_ALIAS("md-raid4");
3744 MODULE_ALIAS("md-level-5");
3745 MODULE_ALIAS("md-level-4");
3746 MODULE_ALIAS("md-personality-8"); /* RAID6 */
3747 MODULE_ALIAS("md-raid6");
3748 MODULE_ALIAS("md-level-6");
3749
3750 /* This used to be two separate modules, they were: */
3751 MODULE_ALIAS("raid5");
3752 MODULE_ALIAS("raid6");