drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *
   6  * RAID-5 management functions.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * (for example /usr/src/linux/COPYING); if not, write to the Free
  15  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  16  */
  17
  18
  19 #include <linux/config.h>
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <linux/raid/raid5.h>
  23 #include <linux/highmem.h>
  24 #include <linux/bitops.h>
  25 #include <asm/atomic.h>
  26
  27 /*
  28  * Stripe cache
  29  */
  30
  31 #define NR_STRIPES              256
  32 #define STRIPE_SIZE             PAGE_SIZE
  33 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  34 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  35 #define IO_THRESHOLD            1
  36 #define HASH_PAGES              1
  37 #define HASH_PAGES_ORDER        0
  38 #define NR_HASH                 (HASH_PAGES * PAGE_SIZE / sizeof(struct stripe_head *))
  39 #define HASH_MASK               (NR_HASH - 1)
  40
  41 #define stripe_hash(conf, sect) ((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK])
  42
  43 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
  44  * order without overlap.  There may be several bio's per stripe+device, and
  45  * a bio could span several devices.
  46  * When walking this list for a particular stripe+device, we must never proceed
  47  * beyond a bio that extends past this device, as the next bio might no longer
  48  * be valid.
  49  * This macro is used to determine the 'next' bio in the list, given the sector
  50  * of the current stripe+device
  51  */
  52 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
  53 /*
  54  * The following can be used to debug the driver
  55  */
  56 #define RAID5_DEBUG     0
  57 #define RAID5_PARANOIA  1
  58 #if RAID5_PARANOIA && defined(CONFIG_SMP)
  59 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
  60 #else
  61 # define CHECK_DEVLOCK()
  62 #endif
  63
  64 #define PRINTK(x...) ((void)(RAID5_DEBUG && printk(x)))
  65 #if RAID5_DEBUG
  66 #define inline
  67 #define __inline__
  68 #endif
  69
  70 static void print_raid5_conf (raid5_conf_t *conf);
  71
  72 static inline void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
  73 {
  74         if (atomic_dec_and_test(&sh->count)) {
  75                 if (!list_empty(&sh->lru))
  76                         BUG();
  77                 if (atomic_read(&conf->active_stripes)==0)
  78                         BUG();
  79                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
  80                         if (test_bit(STRIPE_DELAYED, &sh->state))
  81                                 list_add_tail(&sh->lru, &conf->delayed_list);
  82                         else
  83                                 list_add_tail(&sh->lru, &conf->handle_list);
  84                         md_wakeup_thread(conf->mddev->thread);
  85                 } else {
  86                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
  87                                 atomic_dec(&conf->preread_active_stripes);
  88                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
  89                                         md_wakeup_thread(conf->mddev->thread);
  90                         }
  91                         list_add_tail(&sh->lru, &conf->inactive_list);
  92                         atomic_dec(&conf->active_stripes);
  93                         if (!conf->inactive_blocked ||
  94                             atomic_read(&conf->active_stripes) < (NR_STRIPES*3/4))
  95                                 wake_up(&conf->wait_for_stripe);
  96                 }
  97         }
  98 }
  99 static void release_stripe(struct stripe_head *sh)
 100 {
 101         raid5_conf_t *conf = sh->raid_conf;
 102         unsigned long flags;
 103
 104         spin_lock_irqsave(&conf->device_lock, flags);
 105         __release_stripe(conf, sh);
 106         spin_unlock_irqrestore(&conf->device_lock, flags);
 107 }
 108
 109 static void remove_hash(struct stripe_head *sh)
 110 {
 111         PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 112
 113         if (sh->hash_pprev) {
 114                 if (sh->hash_next)
 115                         sh->hash_next->hash_pprev = sh->hash_pprev;
 116                 *sh->hash_pprev = sh->hash_next;
 117                 sh->hash_pprev = NULL;
 118         }
 119 }
 120
 121 static __inline__ void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
 122 {
 123         struct stripe_head **shp = &stripe_hash(conf, sh->sector);
 124
 125         PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 126
 127         CHECK_DEVLOCK();
 128         if ((sh->hash_next = *shp) != NULL)
 129                 (*shp)->hash_pprev = &sh->hash_next;
 130         *shp = sh;
 131         sh->hash_pprev = shp;
 132 }
 133
 134
 135 /* find an idle stripe, make sure it is unhashed, and return it. */
 136 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
 137 {
 138         struct stripe_head *sh = NULL;
 139         struct list_head *first;
 140
 141         CHECK_DEVLOCK();
 142         if (list_empty(&conf->inactive_list))
 143                 goto out;
 144         first = conf->inactive_list.next;
 145         sh = list_entry(first, struct stripe_head, lru);
 146         list_del_init(first);
 147         remove_hash(sh);
 148         atomic_inc(&conf->active_stripes);
 149 out:
 150         return sh;
 151 }
 152
 153 static void shrink_buffers(struct stripe_head *sh, int num)
 154 {
 155         struct page *p;
 156         int i;
 157
 158         for (i=0; i<num ; i++) {
 159                 p = sh->dev[i].page;
 160                 if (!p)
 161                         continue;
 162                 sh->dev[i].page = NULL;
 163                 page_cache_release(p);
 164         }
 165 }
 166
 167 static int grow_buffers(struct stripe_head *sh, int num)
 168 {
 169         int i;
 170
 171         for (i=0; i<num; i++) {
 172                 struct page *page;
 173
 174                 if (!(page = alloc_page(GFP_KERNEL))) {
 175                         return 1;
 176                 }
 177                 sh->dev[i].page = page;
 178         }
 179         return 0;
 180 }
 181
 182 static void raid5_build_block (struct stripe_head *sh, int i);
 183
 184 static inline void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
 185 {
 186         raid5_conf_t *conf = sh->raid_conf;
 187         int disks = conf->raid_disks, i;
 188
 189         if (atomic_read(&sh->count) != 0)
 190                 BUG();
 191         if (test_bit(STRIPE_HANDLE, &sh->state))
 192                 BUG();
 193
 194         CHECK_DEVLOCK();
 195         PRINTK("init_stripe called, stripe %llu\n",
 196                 (unsigned long long)sh->sector);
 197
 198         remove_hash(sh);
 199
 200         sh->sector = sector;
 201         sh->pd_idx = pd_idx;
 202         sh->state = 0;
 203
 204         for (i=disks; i--; ) {
 205                 struct r5dev *dev = &sh->dev[i];
 206
 207                 if (dev->toread || dev->towrite || dev->written ||
 208                     test_bit(R5_LOCKED, &dev->flags)) {
 209                         printk("sector=%llx i=%d %p %p %p %d\n",
 210                                (unsigned long long)sh->sector, i, dev->toread,
 211                                dev->towrite, dev->written,
 212                                test_bit(R5_LOCKED, &dev->flags));
 213                         BUG();
 214                 }
 215                 dev->flags = 0;
 216                 raid5_build_block(sh, i);
 217         }
 218         insert_hash(conf, sh);
 219 }
 220
 221 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector)
 222 {
 223         struct stripe_head *sh;
 224
 225         CHECK_DEVLOCK();
 226         PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
 227         for (sh = stripe_hash(conf, sector); sh; sh = sh->hash_next)
 228                 if (sh->sector == sector)
 229                         return sh;
 230         PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
 231         return NULL;
 232 }
 233
 234 static void unplug_slaves(mddev_t *mddev);
 235 static void raid5_unplug_device(request_queue_t *q);
 236
 237 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector,
 238                                              int pd_idx, int noblock)
 239 {
 240         struct stripe_head *sh;
 241
 242         PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector);
 243
 244         spin_lock_irq(&conf->device_lock);
 245
 246         do {
 247                 sh = __find_stripe(conf, sector);
 248                 if (!sh) {
 249                         if (!conf->inactive_blocked)
 250                                 sh = get_free_stripe(conf);
 251                         if (noblock && sh == NULL)
 252                                 break;
 253                         if (!sh) {
 254                                 conf->inactive_blocked = 1;
 255                                 wait_event_lock_irq(conf->wait_for_stripe,
 256                                                     !list_empty(&conf->inactive_list) &&
 257                                                     (atomic_read(&conf->active_stripes) < (NR_STRIPES *3/4)
 258                                                      || !conf->inactive_blocked),
 259                                                     conf->device_lock,
 260                                                     unplug_slaves(conf->mddev);
 261                                         );
 262                                 conf->inactive_blocked = 0;
 263                         } else
 264                                 init_stripe(sh, sector, pd_idx);
 265                 } else {
 266                         if (atomic_read(&sh->count)) {
 267                                 if (!list_empty(&sh->lru))
 268                                         BUG();
 269                         } else {
 270                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 271                                         atomic_inc(&conf->active_stripes);
 272                                 if (list_empty(&sh->lru))
 273                                         BUG();
 274                                 list_del_init(&sh->lru);
 275                         }
 276                 }
 277         } while (sh == NULL);
 278
 279         if (sh)
 280                 atomic_inc(&sh->count);
 281
 282         spin_unlock_irq(&conf->device_lock);
 283         return sh;
 284 }
 285
 286 static int grow_stripes(raid5_conf_t *conf, int num)
 287 {
 288         struct stripe_head *sh;
 289         kmem_cache_t *sc;
 290         int devs = conf->raid_disks;
 291
 292         sprintf(conf->cache_name, "raid5/%s", mdname(conf->mddev));
 293
 294         sc = kmem_cache_create(conf->cache_name,
 295                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
 296                                0, 0, NULL, NULL);
 297         if (!sc)
 298                 return 1;
 299         conf->slab_cache = sc;
 300         while (num--) {
 301                 sh = kmem_cache_alloc(sc, GFP_KERNEL);
 302                 if (!sh)
 303                         return 1;
 304                 memset(sh, 0, sizeof(*sh) + (devs-1)*sizeof(struct r5dev));
 305                 sh->raid_conf = conf;
 306                 spin_lock_init(&sh->lock);
 307
 308                 if (grow_buffers(sh, conf->raid_disks)) {
 309                         shrink_buffers(sh, conf->raid_disks);
 310                         kmem_cache_free(sc, sh);
 311                         return 1;
 312                 }
 313                 /* we just created an active stripe so... */
 314                 atomic_set(&sh->count, 1);
 315                 atomic_inc(&conf->active_stripes);
 316                 INIT_LIST_HEAD(&sh->lru);
 317                 release_stripe(sh);
 318         }
 319         return 0;
 320 }
 321
 322 static void shrink_stripes(raid5_conf_t *conf)
 323 {
 324         struct stripe_head *sh;
 325
 326         while (1) {
 327                 spin_lock_irq(&conf->device_lock);
 328                 sh = get_free_stripe(conf);
 329                 spin_unlock_irq(&conf->device_lock);
 330                 if (!sh)
 331                         break;
 332                 if (atomic_read(&sh->count))
 333                         BUG();
 334                 shrink_buffers(sh, conf->raid_disks);
 335                 kmem_cache_free(conf->slab_cache, sh);
 336                 atomic_dec(&conf->active_stripes);
 337         }
 338         kmem_cache_destroy(conf->slab_cache);
 339         conf->slab_cache = NULL;
 340 }
 341
 342 static int raid5_end_read_request (struct bio * bi, unsigned int bytes_done,
 343                                    int error)
 344 {
 345         struct stripe_head *sh = bi->bi_private;
 346         raid5_conf_t *conf = sh->raid_conf;
 347         int disks = conf->raid_disks, i;
 348         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 349
 350         if (bi->bi_size)
 351                 return 1;
 352
 353         for (i=0 ; i<disks; i++)
 354                 if (bi == &sh->dev[i].req)
 355                         break;
 356
 357         PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n",
 358                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
 359                 uptodate);
 360         if (i == disks) {
 361                 BUG();
 362                 return 0;
 363         }
 364
 365         if (uptodate) {
 366 #if 0
 367                 struct bio *bio;
 368                 unsigned long flags;
 369                 spin_lock_irqsave(&conf->device_lock, flags);
 370                 /* we can return a buffer if we bypassed the cache or
 371                  * if the top buffer is not in highmem.  If there are
 372                  * multiple buffers, leave the extra work to
 373                  * handle_stripe
 374                  */
 375                 buffer = sh->bh_read[i];
 376                 if (buffer &&
 377                     (!PageHighMem(buffer->b_page)
 378                      || buffer->b_page == bh->b_page )
 379                         ) {
 380                         sh->bh_read[i] = buffer->b_reqnext;
 381                         buffer->b_reqnext = NULL;
 382                 } else
 383                         buffer = NULL;
 384                 spin_unlock_irqrestore(&conf->device_lock, flags);
 385                 if (sh->bh_page[i]==bh->b_page)
 386                         set_buffer_uptodate(bh);
 387                 if (buffer) {
 388                         if (buffer->b_page != bh->b_page)
 389                                 memcpy(buffer->b_data, bh->b_data, bh->b_size);
 390                         buffer->b_end_io(buffer, 1);
 391                 }
 392 #else
 393                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
 394 #endif
 395         } else {
 396                 md_error(conf->mddev, conf->disks[i].rdev);
 397                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
 398         }
 399         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 400 #if 0
 401         /* must restore b_page before unlocking buffer... */
 402         if (sh->bh_page[i] != bh->b_page) {
 403                 bh->b_page = sh->bh_page[i];
 404                 bh->b_data = page_address(bh->b_page);
 405                 clear_buffer_uptodate(bh);
 406         }
 407 #endif
 408         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 409         set_bit(STRIPE_HANDLE, &sh->state);
 410         release_stripe(sh);
 411         return 0;
 412 }
 413
 414 static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
 415                                     int error)
 416 {
 417         struct stripe_head *sh = bi->bi_private;
 418         raid5_conf_t *conf = sh->raid_conf;
 419         int disks = conf->raid_disks, i;
 420         unsigned long flags;
 421         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 422
 423         if (bi->bi_size)
 424                 return 1;
 425
 426         for (i=0 ; i<disks; i++)
 427                 if (bi == &sh->dev[i].req)
 428                         break;
 429
 430         PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n",
 431                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
 432                 uptodate);
 433         if (i == disks) {
 434                 BUG();
 435                 return 0;
 436         }
 437
 438         spin_lock_irqsave(&conf->device_lock, flags);
 439         if (!uptodate)
 440                 md_error(conf->mddev, conf->disks[i].rdev);
 441
 442         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 443
 444         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 445         set_bit(STRIPE_HANDLE, &sh->state);
 446         __release_stripe(conf, sh);
 447         spin_unlock_irqrestore(&conf->device_lock, flags);
 448         return 0;
 449 }
 450
 451
 452 static sector_t compute_blocknr(struct stripe_head *sh, int i);
 453
 454 static void raid5_build_block (struct stripe_head *sh, int i)
 455 {
 456         struct r5dev *dev = &sh->dev[i];
 457
 458         bio_init(&dev->req);
 459         dev->req.bi_io_vec = &dev->vec;
 460         dev->req.bi_vcnt++;
 461         dev->req.bi_max_vecs++;
 462         dev->vec.bv_page = dev->page;
 463         dev->vec.bv_len = STRIPE_SIZE;
 464         dev->vec.bv_offset = 0;
 465
 466         dev->req.bi_sector = sh->sector;
 467         dev->req.bi_private = sh;
 468
 469         dev->flags = 0;
 470         if (i != sh->pd_idx)
 471                 dev->sector = compute_blocknr(sh, i);
 472 }
 473
 474 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 475 {
 476         char b[BDEVNAME_SIZE];
 477         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
 478         PRINTK("raid5: error called\n");
 479
 480         if (!rdev->faulty) {
 481                 mddev->sb_dirty = 1;
 482                 if (rdev->in_sync) {
 483                         conf->working_disks--;
 484                         mddev->degraded++;
 485                         conf->failed_disks++;
 486                         rdev->in_sync = 0;
 487                         /*
 488                          * if recovery was running, make sure it aborts.
 489                          */
 490                         set_bit(MD_RECOVERY_ERR, &mddev->recovery);
 491                 }
 492                 rdev->faulty = 1;
 493                 printk (KERN_ALERT
 494                         "raid5: Disk failure on %s, disabling device."
 495                         " Operation continuing on %d devices\n",
 496                         bdevname(rdev->bdev,b), conf->working_disks);
 497         }
 498 }
 499
 500 /*
 501  * Input: a 'big' sector number,
 502  * Output: index of the data and parity disk, and the sector # in them.
 503  */
 504 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
 505                         unsigned int data_disks, unsigned int * dd_idx,
 506                         unsigned int * pd_idx, raid5_conf_t *conf)
 507 {
 508         long stripe;
 509         unsigned long chunk_number;
 510         unsigned int chunk_offset;
 511         sector_t new_sector;
 512         int sectors_per_chunk = conf->chunk_size >> 9;
 513
 514         /* First compute the information on this sector */
 515
 516         /*
 517          * Compute the chunk number and the sector offset inside the chunk
 518          */
 519         chunk_offset = sector_div(r_sector, sectors_per_chunk);
 520         chunk_number = r_sector;
 521         BUG_ON(r_sector != chunk_number);
 522
 523         /*
 524          * Compute the stripe number
 525          */
 526         stripe = chunk_number / data_disks;
 527
 528         /*
 529          * Compute the data disk and parity disk indexes inside the stripe
 530          */
 531         *dd_idx = chunk_number % data_disks;
 532
 533         /*
 534          * Select the parity disk based on the user selected algorithm.
 535          */
 536         if (conf->level == 4)
 537                 *pd_idx = data_disks;
 538         else switch (conf->algorithm) {
 539                 case ALGORITHM_LEFT_ASYMMETRIC:
 540                         *pd_idx = data_disks - stripe % raid_disks;
 541                         if (*dd_idx >= *pd_idx)
 542                                 (*dd_idx)++;
 543                         break;
 544                 case ALGORITHM_RIGHT_ASYMMETRIC:
 545                         *pd_idx = stripe % raid_disks;
 546                         if (*dd_idx >= *pd_idx)
 547                                 (*dd_idx)++;
 548                         break;
 549                 case ALGORITHM_LEFT_SYMMETRIC:
 550                         *pd_idx = data_disks - stripe % raid_disks;
 551                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
 552                         break;
 553                 case ALGORITHM_RIGHT_SYMMETRIC:
 554                         *pd_idx = stripe % raid_disks;
 555                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
 556                         break;
 557                 default:
 558                         printk("raid5: unsupported algorithm %d\n",
 559                                 conf->algorithm);
 560         }
 561
 562         /*
 563          * Finally, compute the new sector number
 564          */
 565         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
 566         return new_sector;
 567 }
 568
 569
 570 static sector_t compute_blocknr(struct stripe_head *sh, int i)
 571 {
 572         raid5_conf_t *conf = sh->raid_conf;
 573         int raid_disks = conf->raid_disks, data_disks = raid_disks - 1;
 574         sector_t new_sector = sh->sector, check;
 575         int sectors_per_chunk = conf->chunk_size >> 9;
 576         sector_t stripe;
 577         int chunk_offset;
 578         int chunk_number, dummy1, dummy2, dd_idx = i;
 579         sector_t r_sector;
 580
 581         chunk_offset = sector_div(new_sector, sectors_per_chunk);
 582         stripe = new_sector;
 583         BUG_ON(new_sector != stripe);
 584
 585
 586         switch (conf->algorithm) {
 587                 case ALGORITHM_LEFT_ASYMMETRIC:
 588                 case ALGORITHM_RIGHT_ASYMMETRIC:
 589                         if (i > sh->pd_idx)
 590                                 i--;
 591                         break;
 592                 case ALGORITHM_LEFT_SYMMETRIC:
 593                 case ALGORITHM_RIGHT_SYMMETRIC:
 594                         if (i < sh->pd_idx)
 595                                 i += raid_disks;
 596                         i -= (sh->pd_idx + 1);
 597                         break;
 598                 default:
 599                         printk("raid5: unsupported algorithm %d\n",
 600                                 conf->algorithm);
 601         }
 602
 603         chunk_number = stripe * data_disks + i;
 604         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
 605
 606         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
 607         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
 608                 printk("compute_blocknr: map not correct\n");
 609                 return 0;
 610         }
 611         return r_sector;
 612 }
 613
 614
 615
 616 /*
 617  * Copy data between a page in the stripe cache, and a bio.
 618  * There are no alignment or size guarantees between the page or the
 619  * bio except that there is some overlap.
 620  * All iovecs in the bio must be considered.
 621  */
 622 static void copy_data(int frombio, struct bio *bio,
 623                      struct page *page,
 624                      sector_t sector)
 625 {
 626         char *pa = page_address(page);
 627         struct bio_vec *bvl;
 628         int i;
 629         int page_offset;
 630
 631         if (bio->bi_sector >= sector)
 632                 page_offset = (signed)(bio->bi_sector - sector) * 512;
 633         else
 634                 page_offset = (signed)(sector - bio->bi_sector) * -512;
 635         bio_for_each_segment(bvl, bio, i) {
 636                 int len = bio_iovec_idx(bio,i)->bv_len;
 637                 int clen;
 638                 int b_offset = 0;
 639
 640                 if (page_offset < 0) {
 641                         b_offset = -page_offset;
 642                         page_offset += b_offset;
 643                         len -= b_offset;
 644                 }
 645
 646                 if (len > 0 && page_offset + len > STRIPE_SIZE)
 647                         clen = STRIPE_SIZE - page_offset;
 648                 else clen = len;
 649
 650                 if (clen > 0) {
 651                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
 652                         if (frombio)
 653                                 memcpy(pa+page_offset, ba+b_offset, clen);
 654                         else
 655                                 memcpy(ba+b_offset, pa+page_offset, clen);
 656                         __bio_kunmap_atomic(ba, KM_USER0);
 657                 }
 658                 if (clen < len) /* hit end of page */
 659                         break;
 660                 page_offset +=  len;
 661         }
 662 }
 663
 664 #define check_xor()     do {                                            \
 665                            if (count == MAX_XOR_BLOCKS) {               \
 666                                 xor_block(count, STRIPE_SIZE, ptr);     \
 667                                 count = 1;                              \
 668                            }                                            \
 669                         } while(0)
 670
 671
 672 static void compute_block(struct stripe_head *sh, int dd_idx)
 673 {
 674         raid5_conf_t *conf = sh->raid_conf;
 675         int i, count, disks = conf->raid_disks;
 676         void *ptr[MAX_XOR_BLOCKS], *p;
 677
 678         PRINTK("compute_block, stripe %llu, idx %d\n",
 679                 (unsigned long long)sh->sector, dd_idx);
 680
 681         ptr[0] = page_address(sh->dev[dd_idx].page);
 682         memset(ptr[0], 0, STRIPE_SIZE);
 683         count = 1;
 684         for (i = disks ; i--; ) {
 685                 if (i == dd_idx)
 686                         continue;
 687                 p = page_address(sh->dev[i].page);
 688                 if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
 689                         ptr[count++] = p;
 690                 else
 691                         printk("compute_block() %d, stripe %llu, %d"
 692                                 " not present\n", dd_idx,
 693                                 (unsigned long long)sh->sector, i);
 694
 695                 check_xor();
 696         }
 697         if (count != 1)
 698                 xor_block(count, STRIPE_SIZE, ptr);
 699         set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
 700 }
 701
 702 static void compute_parity(struct stripe_head *sh, int method)
 703 {
 704         raid5_conf_t *conf = sh->raid_conf;
 705         int i, pd_idx = sh->pd_idx, disks = conf->raid_disks, count;
 706         void *ptr[MAX_XOR_BLOCKS];
 707         struct bio *chosen;
 708
 709         PRINTK("compute_parity, stripe %llu, method %d\n",
 710                 (unsigned long long)sh->sector, method);
 711
 712         count = 1;
 713         ptr[0] = page_address(sh->dev[pd_idx].page);
 714         switch(method) {
 715         case READ_MODIFY_WRITE:
 716                 if (!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags))
 717                         BUG();
 718                 for (i=disks ; i-- ;) {
 719                         if (i==pd_idx)
 720                                 continue;
 721                         if (sh->dev[i].towrite &&
 722                             test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
 723                                 ptr[count++] = page_address(sh->dev[i].page);
 724                                 chosen = sh->dev[i].towrite;
 725                                 sh->dev[i].towrite = NULL;
 726
 727                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 728                                         wake_up(&conf->wait_for_overlap);
 729
 730                                 if (sh->dev[i].written) BUG();
 731                                 sh->dev[i].written = chosen;
 732                                 check_xor();
 733                         }
 734                 }
 735                 break;
 736         case RECONSTRUCT_WRITE:
 737                 memset(ptr[0], 0, STRIPE_SIZE);
 738                 for (i= disks; i-- ;)
 739                         if (i!=pd_idx && sh->dev[i].towrite) {
 740                                 chosen = sh->dev[i].towrite;
 741                                 sh->dev[i].towrite = NULL;
 742
 743                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 744                                         wake_up(&conf->wait_for_overlap);
 745
 746                                 if (sh->dev[i].written) BUG();
 747                                 sh->dev[i].written = chosen;
 748                         }
 749                 break;
 750         case CHECK_PARITY:
 751                 break;
 752         }
 753         if (count>1) {
 754                 xor_block(count, STRIPE_SIZE, ptr);
 755                 count = 1;
 756         }
 757
 758         for (i = disks; i--;)
 759                 if (sh->dev[i].written) {
 760                         sector_t sector = sh->dev[i].sector;
 761                         struct bio *wbi = sh->dev[i].written;
 762                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
 763                                 copy_data(1, wbi, sh->dev[i].page, sector);
 764                                 wbi = r5_next_bio(wbi, sector);
 765                         }
 766
 767                         set_bit(R5_LOCKED, &sh->dev[i].flags);
 768                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
 769                 }
 770
 771         switch(method) {
 772         case RECONSTRUCT_WRITE:
 773         case CHECK_PARITY:
 774                 for (i=disks; i--;)
 775                         if (i != pd_idx) {
 776                                 ptr[count++] = page_address(sh->dev[i].page);
 777                                 check_xor();
 778                         }
 779                 break;
 780         case READ_MODIFY_WRITE:
 781                 for (i = disks; i--;)
 782                         if (sh->dev[i].written) {
 783                                 ptr[count++] = page_address(sh->dev[i].page);
 784                                 check_xor();
 785                         }
 786         }
 787         if (count != 1)
 788                 xor_block(count, STRIPE_SIZE, ptr);
 789
 790         if (method != CHECK_PARITY) {
 791                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 792                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
 793         } else
 794                 clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 795 }
 796
 797 /*
 798  * Each stripe/dev can have one or more bion attached.
 799  * toread/towrite point to the first in a chain.
 800  * The bi_next chain must be in order.
 801  */
 802 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
 803 {
 804         struct bio **bip;
 805         raid5_conf_t *conf = sh->raid_conf;
 806
 807         PRINTK("adding bh b#%llu to stripe s#%llu\n",
 808                 (unsigned long long)bi->bi_sector,
 809                 (unsigned long long)sh->sector);
 810
 811
 812         spin_lock(&sh->lock);
 813         spin_lock_irq(&conf->device_lock);
 814         if (forwrite)
 815                 bip = &sh->dev[dd_idx].towrite;
 816         else
 817                 bip = &sh->dev[dd_idx].toread;
 818         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
 819                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
 820                         goto overlap;
 821                 bip = & (*bip)->bi_next;
 822         }
 823         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
 824                 goto overlap;
 825
 826         if (*bip && bi->bi_next && (*bip) != bi->bi_next)
 827                 BUG();
 828         if (*bip)
 829                 bi->bi_next = *bip;
 830         *bip = bi;
 831         bi->bi_phys_segments ++;
 832         spin_unlock_irq(&conf->device_lock);
 833         spin_unlock(&sh->lock);
 834
 835         PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n",
 836                 (unsigned long long)bi->bi_sector,
 837                 (unsigned long long)sh->sector, dd_idx);
 838
 839         if (forwrite) {
 840                 /* check if page is covered */
 841                 sector_t sector = sh->dev[dd_idx].sector;
 842                 for (bi=sh->dev[dd_idx].towrite;
 843                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
 844                              bi && bi->bi_sector <= sector;
 845                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
 846                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
 847                                 sector = bi->bi_sector + (bi->bi_size>>9);
 848                 }
 849                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
 850                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
 851         }
 852         return 1;
 853
 854  overlap:
 855         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
 856         spin_unlock_irq(&conf->device_lock);
 857         spin_unlock(&sh->lock);
 858         return 0;
 859 }
 860
 861
 862 /*
 863  * handle_stripe - do things to a stripe.
 864  *
 865  * We lock the stripe and then examine the state of various bits
 866  * to see what needs to be done.
 867  * Possible results:
 868  *    return some read request which now have data
 869  *    return some write requests which are safely on disc
 870  *    schedule a read on some buffers
 871  *    schedule a write of some buffers
 872  *    return confirmation of parity correctness
 873  *
 874  * Parity calculations are done inside the stripe lock
 875  * buffers are taken off read_list or write_list, and bh_cache buffers
 876  * get BH_Lock set before the stripe lock is released.
 877  *
 878  */
 879
 880 static void handle_stripe(struct stripe_head *sh)
 881 {
 882         raid5_conf_t *conf = sh->raid_conf;
 883         int disks = conf->raid_disks;
 884         struct bio *return_bi= NULL;
 885         struct bio *bi;
 886         int i;
 887         int syncing;
 888         int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
 889         int non_overwrite = 0;
 890         int failed_num=0;
 891         struct r5dev *dev;
 892
 893         PRINTK("handling stripe %llu, cnt=%d, pd_idx=%d\n",
 894                 (unsigned long long)sh->sector, atomic_read(&sh->count),
 895                 sh->pd_idx);
 896
 897         spin_lock(&sh->lock);
 898         clear_bit(STRIPE_HANDLE, &sh->state);
 899         clear_bit(STRIPE_DELAYED, &sh->state);
 900
 901         syncing = test_bit(STRIPE_SYNCING, &sh->state);
 902         /* Now to look around and see what can be done */
 903
 904         for (i=disks; i--; ) {
 905                 mdk_rdev_t *rdev;
 906                 dev = &sh->dev[i];
 907                 clear_bit(R5_Insync, &dev->flags);
 908                 clear_bit(R5_Syncio, &dev->flags);
 909
 910                 PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
 911                         i, dev->flags, dev->toread, dev->towrite, dev->written);
 912                 /* maybe we can reply to a read */
 913                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
 914                         struct bio *rbi, *rbi2;
 915                         PRINTK("Return read for disc %d\n", i);
 916                         spin_lock_irq(&conf->device_lock);
 917                         rbi = dev->toread;
 918                         dev->toread = NULL;
 919                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
 920                                 wake_up(&conf->wait_for_overlap);
 921                         spin_unlock_irq(&conf->device_lock);
 922                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
 923                                 copy_data(0, rbi, dev->page, dev->sector);
 924                                 rbi2 = r5_next_bio(rbi, dev->sector);
 925                                 spin_lock_irq(&conf->device_lock);
 926                                 if (--rbi->bi_phys_segments == 0) {
 927                                         rbi->bi_next = return_bi;
 928                                         return_bi = rbi;
 929                                 }
 930                                 spin_unlock_irq(&conf->device_lock);
 931                                 rbi = rbi2;
 932                         }
 933                 }
 934
 935                 /* now count some things */
 936                 if (test_bit(R5_LOCKED, &dev->flags)) locked++;
 937                 if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
 938
 939
 940                 if (dev->toread) to_read++;
 941                 if (dev->towrite) {
 942                         to_write++;
 943                         if (!test_bit(R5_OVERWRITE, &dev->flags))
 944                                 non_overwrite++;
 945                 }
 946                 if (dev->written) written++;
 947                 rdev = conf->disks[i].rdev; /* FIXME, should I be looking rdev */
 948                 if (!rdev || !rdev->in_sync) {
 949                         failed++;
 950                         failed_num = i;
 951                 } else
 952                         set_bit(R5_Insync, &dev->flags);
 953         }
 954         PRINTK("locked=%d uptodate=%d to_read=%d"
 955                 " to_write=%d failed=%d failed_num=%d\n",
 956                 locked, uptodate, to_read, to_write, failed, failed_num);
 957         /* check if the array has lost two devices and, if so, some requests might
 958          * need to be failed
 959          */
 960         if (failed > 1 && to_read+to_write+written) {
 961                 spin_lock_irq(&conf->device_lock);
 962                 for (i=disks; i--; ) {
 963                         /* fail all writes first */
 964                         bi = sh->dev[i].towrite;
 965                         sh->dev[i].towrite = NULL;
 966                         if (bi) to_write--;
 967
 968                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 969                                 wake_up(&conf->wait_for_overlap);
 970
 971                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
 972                                 struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
 973                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
 974                                 if (--bi->bi_phys_segments == 0) {
 975                                         md_write_end(conf->mddev);
 976                                         bi->bi_next = return_bi;
 977                                         return_bi = bi;
 978                                 }
 979                                 bi = nextbi;
 980                         }
 981                         /* and fail all 'written' */
 982                         bi = sh->dev[i].written;
 983                         sh->dev[i].written = NULL;
 984                         while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
 985                                 struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
 986                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
 987                                 if (--bi->bi_phys_segments == 0) {
 988                                         md_write_end(conf->mddev);
 989                                         bi->bi_next = return_bi;
 990                                         return_bi = bi;
 991                                 }
 992                                 bi = bi2;
 993                         }
 994
 995                         /* fail any reads if this device is non-operational */
 996                         if (!test_bit(R5_Insync, &sh->dev[i].flags)) {
 997                                 bi = sh->dev[i].toread;
 998                                 sh->dev[i].toread = NULL;
 999                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1000                                         wake_up(&conf->wait_for_overlap);
1001                                 if (bi) to_read--;
1002                                 while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
1003                                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
1004                                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1005                                         if (--bi->bi_phys_segments == 0) {
1006                                                 bi->bi_next = return_bi;
1007                                                 return_bi = bi;
1008                                         }
1009                                         bi = nextbi;
1010                                 }
1011                         }
1012                 }
1013                 spin_unlock_irq(&conf->device_lock);
1014         }
1015         if (failed > 1 && syncing) {
1016                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
1017                 clear_bit(STRIPE_SYNCING, &sh->state);
1018                 syncing = 0;
1019         }
1020
1021         /* might be able to return some write requests if the parity block
1022          * is safe, or on a failed drive
1023          */
1024         dev = &sh->dev[sh->pd_idx];
1025         if ( written &&
1026              ( (test_bit(R5_Insync, &dev->flags) && !test_bit(R5_LOCKED, &dev->flags) &&
1027                 test_bit(R5_UPTODATE, &dev->flags))
1028                || (failed == 1 && failed_num == sh->pd_idx))
1029             ) {
1030             /* any written block on an uptodate or failed drive can be returned.
1031              * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
1032              * never LOCKED, so we don't need to test 'failed' directly.
1033              */
1034             for (i=disks; i--; )
1035                 if (sh->dev[i].written) {
1036                     dev = &sh->dev[i];
1037                     if (!test_bit(R5_LOCKED, &dev->flags) &&
1038                          test_bit(R5_UPTODATE, &dev->flags) ) {
1039                         /* We can return any write requests */
1040                             struct bio *wbi, *wbi2;
1041                             PRINTK("Return write for disc %d\n", i);
1042                             spin_lock_irq(&conf->device_lock);
1043                             wbi = dev->written;
1044                             dev->written = NULL;
1045                             while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) {
1046                                     wbi2 = r5_next_bio(wbi, dev->sector);
1047                                     if (--wbi->bi_phys_segments == 0) {
1048                                             md_write_end(conf->mddev);
1049                                             wbi->bi_next = return_bi;
1050                                             return_bi = wbi;
1051                                     }
1052                                     wbi = wbi2;
1053                             }
1054                             spin_unlock_irq(&conf->device_lock);
1055                     }
1056                 }
1057         }
1058
1059         /* Now we might consider reading some blocks, either to check/generate
1060          * parity, or to satisfy requests
1061          * or to load a block that is being partially written.
1062          */
1063         if (to_read || non_overwrite || (syncing && (uptodate < disks))) {
1064                 for (i=disks; i--;) {
1065                         dev = &sh->dev[i];
1066                         if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1067                             (dev->toread ||
1068                              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
1069                              syncing ||
1070                              (failed && (sh->dev[failed_num].toread ||
1071                                          (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags))))
1072                                     )
1073                                 ) {
1074                                 /* we would like to get this block, possibly
1075                                  * by computing it, but we might not be able to
1076                                  */
1077                                 if (uptodate == disks-1) {
1078                                         PRINTK("Computing block %d\n", i);
1079                                         compute_block(sh, i);
1080                                         uptodate++;
1081                                 } else if (test_bit(R5_Insync, &dev->flags)) {
1082                                         set_bit(R5_LOCKED, &dev->flags);
1083                                         set_bit(R5_Wantread, &dev->flags);
1084 #if 0
1085                                         /* if I am just reading this block and we don't have
1086                                            a failed drive, or any pending writes then sidestep the cache */
1087                                         if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext &&
1088                                             ! syncing && !failed && !to_write) {
1089                                                 sh->bh_cache[i]->b_page =  sh->bh_read[i]->b_page;
1090                                                 sh->bh_cache[i]->b_data =  sh->bh_read[i]->b_data;
1091                                         }
1092 #endif
1093                                         locked++;
1094                                         PRINTK("Reading block %d (sync=%d)\n",
1095                                                 i, syncing);
1096                                         if (syncing)
1097                                                 md_sync_acct(conf->disks[i].rdev->bdev,
1098                                                              STRIPE_SECTORS);
1099                                 }
1100                         }
1101                 }
1102                 set_bit(STRIPE_HANDLE, &sh->state);
1103         }
1104
1105         /* now to consider writing and what else, if anything should be read */
1106         if (to_write) {
1107                 int rmw=0, rcw=0;
1108                 for (i=disks ; i--;) {
1109                         /* would I have to read this buffer for read_modify_write */
1110                         dev = &sh->dev[i];
1111                         if ((dev->towrite || i == sh->pd_idx) &&
1112                             (!test_bit(R5_LOCKED, &dev->flags)
1113 #if 0
1114 || sh->bh_page[i]!=bh->b_page
1115 #endif
1116                                     ) &&
1117                             !test_bit(R5_UPTODATE, &dev->flags)) {
1118                                 if (test_bit(R5_Insync, &dev->flags)
1119 /*                                  && !(!mddev->insync && i == sh->pd_idx) */
1120                                         )
1121                                         rmw++;
1122                                 else rmw += 2*disks;  /* cannot read it */
1123                         }
1124                         /* Would I have to read this buffer for reconstruct_write */
1125                         if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1126                             (!test_bit(R5_LOCKED, &dev->flags)
1127 #if 0
1128 || sh->bh_page[i] != bh->b_page
1129 #endif
1130                                     ) &&
1131                             !test_bit(R5_UPTODATE, &dev->flags)) {
1132                                 if (test_bit(R5_Insync, &dev->flags)) rcw++;
1133                                 else rcw += 2*disks;
1134                         }
1135                 }
1136                 PRINTK("for sector %llu, rmw=%d rcw=%d\n",
1137                         (unsigned long long)sh->sector, rmw, rcw);
1138                 set_bit(STRIPE_HANDLE, &sh->state);
1139                 if (rmw < rcw && rmw > 0)
1140                         /* prefer read-modify-write, but need to get some data */
1141                         for (i=disks; i--;) {
1142                                 dev = &sh->dev[i];
1143                                 if ((dev->towrite || i == sh->pd_idx) &&
1144                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1145                                     test_bit(R5_Insync, &dev->flags)) {
1146                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1147                                         {
1148                                                 PRINTK("Read_old block %d for r-m-w\n", i);
1149                                                 set_bit(R5_LOCKED, &dev->flags);
1150                                                 set_bit(R5_Wantread, &dev->flags);
1151                                                 locked++;
1152                                         } else {
1153                                                 set_bit(STRIPE_DELAYED, &sh->state);
1154                                                 set_bit(STRIPE_HANDLE, &sh->state);
1155                                         }
1156                                 }
1157                         }
1158                 if (rcw <= rmw && rcw > 0)
1159                         /* want reconstruct write, but need to get some data */
1160                         for (i=disks; i--;) {
1161                                 dev = &sh->dev[i];
1162                                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
1163                                     !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
1164                                     test_bit(R5_Insync, &dev->flags)) {
1165                                         if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1166                                         {
1167                                                 PRINTK("Read_old block %d for Reconstruct\n", i);
1168                                                 set_bit(R5_LOCKED, &dev->flags);
1169                                                 set_bit(R5_Wantread, &dev->flags);
1170                                                 locked++;
1171                                         } else {
1172                                                 set_bit(STRIPE_DELAYED, &sh->state);
1173                                                 set_bit(STRIPE_HANDLE, &sh->state);
1174                                         }
1175                                 }
1176                         }
1177                 /* now if nothing is locked, and if we have enough data, we can start a write request */
1178                 if (locked == 0 && (rcw == 0 ||rmw == 0)) {
1179                         PRINTK("Computing parity...\n");
1180                         compute_parity(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
1181                         /* now every locked buffer is ready to be written */
1182                         for (i=disks; i--;)
1183                                 if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
1184                                         PRINTK("Writing block %d\n", i);
1185                                         locked++;
1186                                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
1187                                         if (!test_bit(R5_Insync, &sh->dev[i].flags)
1188                                             || (i==sh->pd_idx && failed == 0))
1189                                                 set_bit(STRIPE_INSYNC, &sh->state);
1190                                 }
1191                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
1192                                 atomic_dec(&conf->preread_active_stripes);
1193                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
1194                                         md_wakeup_thread(conf->mddev->thread);
1195                         }
1196                 }
1197         }
1198
1199         /* maybe we need to check and possibly fix the parity for this stripe
1200          * Any reads will already have been scheduled, so we just see if enough data
1201          * is available
1202          */
1203         if (syncing && locked == 0 &&
1204             !test_bit(STRIPE_INSYNC, &sh->state) && failed <= 1) {
1205                 set_bit(STRIPE_HANDLE, &sh->state);
1206                 if (failed == 0) {
1207                         char *pagea;
1208                         if (uptodate != disks)
1209                                 BUG();
1210                         compute_parity(sh, CHECK_PARITY);
1211                         uptodate--;
1212                         pagea = page_address(sh->dev[sh->pd_idx].page);
1213                         if ((*(u32*)pagea) == 0 &&
1214                             !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) {
1215                                 /* parity is correct (on disc, not in buffer any more) */
1216                                 set_bit(STRIPE_INSYNC, &sh->state);
1217                         }
1218                 }
1219                 if (!test_bit(STRIPE_INSYNC, &sh->state)) {
1220                         if (failed==0)
1221                                 failed_num = sh->pd_idx;
1222                         /* should be able to compute the missing block and write it to spare */
1223                         if (!test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)) {
1224                                 if (uptodate+1 != disks)
1225                                         BUG();
1226                                 compute_block(sh, failed_num);
1227                                 uptodate++;
1228                         }
1229                         if (uptodate != disks)
1230                                 BUG();
1231                         dev = &sh->dev[failed_num];
1232                         set_bit(R5_LOCKED, &dev->flags);
1233                         set_bit(R5_Wantwrite, &dev->flags);
1234                         locked++;
1235                         set_bit(STRIPE_INSYNC, &sh->state);
1236                         set_bit(R5_Syncio, &dev->flags);
1237                 }
1238         }
1239         if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
1240                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
1241                 clear_bit(STRIPE_SYNCING, &sh->state);
1242         }
1243
1244         spin_unlock(&sh->lock);
1245
1246         while ((bi=return_bi)) {
1247                 int bytes = bi->bi_size;
1248
1249                 return_bi = bi->bi_next;
1250                 bi->bi_next = NULL;
1251                 bi->bi_size = 0;
1252                 bi->bi_end_io(bi, bytes, 0);
1253         }
1254         for (i=disks; i-- ;) {
1255                 int rw;
1256                 struct bio *bi;
1257                 mdk_rdev_t *rdev;
1258                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
1259                         rw = 1;
1260                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
1261                         rw = 0;
1262                 else
1263                         continue;
1264
1265                 bi = &sh->dev[i].req;
1266
1267                 bi->bi_rw = rw;
1268                 if (rw)
1269                         bi->bi_end_io = raid5_end_write_request;
1270                 else
1271                         bi->bi_end_io = raid5_end_read_request;
1272
1273                 rcu_read_lock();
1274                 rdev = conf->disks[i].rdev;
1275                 if (rdev && rdev->faulty)
1276                         rdev = NULL;
1277                 if (rdev)
1278                         atomic_inc(&rdev->nr_pending);
1279                 rcu_read_unlock();
1280
1281                 if (rdev) {
1282                         if (test_bit(R5_Syncio, &sh->dev[i].flags))
1283                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1284
1285                         bi->bi_bdev = rdev->bdev;
1286                         PRINTK("for %llu schedule op %ld on disc %d\n",
1287                                 (unsigned long long)sh->sector, bi->bi_rw, i);
1288                         atomic_inc(&sh->count);
1289                         bi->bi_sector = sh->sector + rdev->data_offset;
1290                         bi->bi_flags = 1 << BIO_UPTODATE;
1291                         bi->bi_vcnt = 1;
1292                         bi->bi_max_vecs = 1;
1293                         bi->bi_idx = 0;
1294                         bi->bi_io_vec = &sh->dev[i].vec;
1295                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1296                         bi->bi_io_vec[0].bv_offset = 0;
1297                         bi->bi_size = STRIPE_SIZE;
1298                         bi->bi_next = NULL;
1299                         generic_make_request(bi);
1300                 } else {
1301                         PRINTK("skip op %ld on disc %d for sector %llu\n",
1302                                 bi->bi_rw, i, (unsigned long long)sh->sector);
1303                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1304                         set_bit(STRIPE_HANDLE, &sh->state);
1305                 }
1306         }
1307 }
1308
1309 static inline void raid5_activate_delayed(raid5_conf_t *conf)
1310 {
1311         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
1312                 while (!list_empty(&conf->delayed_list)) {
1313                         struct list_head *l = conf->delayed_list.next;
1314                         struct stripe_head *sh;
1315                         sh = list_entry(l, struct stripe_head, lru);
1316                         list_del_init(l);
1317                         clear_bit(STRIPE_DELAYED, &sh->state);
1318                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
1319                                 atomic_inc(&conf->preread_active_stripes);
1320                         list_add_tail(&sh->lru, &conf->handle_list);
1321                 }
1322         }
1323 }
1324
1325 static void unplug_slaves(mddev_t *mddev)
1326 {
1327         raid5_conf_t *conf = mddev_to_conf(mddev);
1328         int i;
1329
1330         rcu_read_lock();
1331         for (i=0; i<mddev->raid_disks; i++) {
1332                 mdk_rdev_t *rdev = conf->disks[i].rdev;
1333                 if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
1334                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
1335
1336                         atomic_inc(&rdev->nr_pending);
1337                         rcu_read_unlock();
1338
1339                         if (r_queue->unplug_fn)
1340                                 r_queue->unplug_fn(r_queue);
1341
1342                         rdev_dec_pending(rdev, mddev);
1343                         rcu_read_lock();
1344                 }
1345         }
1346         rcu_read_unlock();
1347 }
1348
1349 static void raid5_unplug_device(request_queue_t *q)
1350 {
1351         mddev_t *mddev = q->queuedata;
1352         raid5_conf_t *conf = mddev_to_conf(mddev);
1353         unsigned long flags;
1354
1355         spin_lock_irqsave(&conf->device_lock, flags);
1356
1357         if (blk_remove_plug(q))
1358                 raid5_activate_delayed(conf);
1359         md_wakeup_thread(mddev->thread);
1360
1361         spin_unlock_irqrestore(&conf->device_lock, flags);
1362
1363         unplug_slaves(mddev);
1364 }
1365
1366 static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk,
1367                              sector_t *error_sector)
1368 {
1369         mddev_t *mddev = q->queuedata;
1370         raid5_conf_t *conf = mddev_to_conf(mddev);
1371         int i, ret = 0;
1372
1373         rcu_read_lock();
1374         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
1375                 mdk_rdev_t *rdev = conf->disks[i].rdev;
1376                 if (rdev && !rdev->faulty) {
1377                         struct block_device *bdev = rdev->bdev;
1378                         request_queue_t *r_queue = bdev_get_queue(bdev);
1379
1380                         if (!r_queue->issue_flush_fn)
1381                                 ret = -EOPNOTSUPP;
1382                         else {
1383                                 atomic_inc(&rdev->nr_pending);
1384                                 rcu_read_unlock();
1385                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
1386                                                               error_sector);
1387                                 rdev_dec_pending(rdev, mddev);
1388                                 rcu_read_lock();
1389                         }
1390                 }
1391         }
1392         rcu_read_unlock();
1393         return ret;
1394 }
1395
1396 static inline void raid5_plug_device(raid5_conf_t *conf)
1397 {
1398         spin_lock_irq(&conf->device_lock);
1399         blk_plug_device(conf->mddev->queue);
1400         spin_unlock_irq(&conf->device_lock);
1401 }
1402
1403 static int make_request (request_queue_t *q, struct bio * bi)
1404 {
1405         mddev_t *mddev = q->queuedata;
1406         raid5_conf_t *conf = mddev_to_conf(mddev);
1407         const unsigned int raid_disks = conf->raid_disks;
1408         const unsigned int data_disks = raid_disks - 1;
1409         unsigned int dd_idx, pd_idx;
1410         sector_t new_sector;
1411         sector_t logical_sector, last_sector;
1412         struct stripe_head *sh;
1413
1414         if (bio_data_dir(bi)==WRITE) {
1415                 disk_stat_inc(mddev->gendisk, writes);
1416                 disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bi));
1417         } else {
1418                 disk_stat_inc(mddev->gendisk, reads);
1419                 disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bi));
1420         }
1421
1422         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
1423         last_sector = bi->bi_sector + (bi->bi_size>>9);
1424         bi->bi_next = NULL;
1425         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
1426         if ( bio_data_dir(bi) == WRITE )
1427                 md_write_start(mddev);
1428         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
1429                 DEFINE_WAIT(w);
1430
1431                 new_sector = raid5_compute_sector(logical_sector,
1432                                                   raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1433
1434                 PRINTK("raid5: make_request, sector %llu logical %llu\n",
1435                         (unsigned long long)new_sector,
1436                         (unsigned long long)logical_sector);
1437
1438         retry:
1439                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
1440                 sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
1441                 if (sh) {
1442                         if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
1443                                 /* Add failed due to overlap.  Flush everything
1444                                  * and wait a while
1445                                  */
1446                                 raid5_unplug_device(mddev->queue);
1447                                 release_stripe(sh);
1448                                 schedule();
1449                                 goto retry;
1450                         }
1451                         finish_wait(&conf->wait_for_overlap, &w);
1452                         raid5_plug_device(conf);
1453                         handle_stripe(sh);
1454                         release_stripe(sh);
1455
1456                 } else {
1457                         /* cannot get stripe for read-ahead, just give-up */
1458                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
1459                         finish_wait(&conf->wait_for_overlap, &w);
1460                         break;
1461                 }
1462
1463         }
1464         spin_lock_irq(&conf->device_lock);
1465         if (--bi->bi_phys_segments == 0) {
1466                 int bytes = bi->bi_size;
1467
1468                 if ( bio_data_dir(bi) == WRITE )
1469                         md_write_end(mddev);
1470                 bi->bi_size = 0;
1471                 bi->bi_end_io(bi, bytes, 0);
1472         }
1473         spin_unlock_irq(&conf->device_lock);
1474         return 0;
1475 }
1476
1477 /* FIXME go_faster isn't used */
1478 static int sync_request (mddev_t *mddev, sector_t sector_nr, int go_faster)
1479 {
1480         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1481         struct stripe_head *sh;
1482         int sectors_per_chunk = conf->chunk_size >> 9;
1483         sector_t x;
1484         unsigned long stripe;
1485         int chunk_offset;
1486         int dd_idx, pd_idx;
1487         sector_t first_sector;
1488         int raid_disks = conf->raid_disks;
1489         int data_disks = raid_disks-1;
1490
1491         if (sector_nr >= mddev->size <<1) {
1492                 /* just being told to finish up .. nothing much to do */
1493                 unplug_slaves(mddev);
1494                 return 0;
1495         }
1496         /* if there is 1 or more failed drives and we are trying
1497          * to resync, then assert that we are finished, because there is
1498          * nothing we can do.
1499          */
1500         if (mddev->degraded >= 1 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1501                 int rv = (mddev->size << 1) - sector_nr;
1502                 md_done_sync(mddev, rv, 1);
1503                 return rv;
1504         }
1505
1506         x = sector_nr;
1507         chunk_offset = sector_div(x, sectors_per_chunk);
1508         stripe = x;
1509         BUG_ON(x != stripe);
1510
1511         first_sector = raid5_compute_sector((sector_t)stripe*data_disks*sectors_per_chunk
1512                 + chunk_offset, raid_disks, data_disks, &dd_idx, &pd_idx, conf);
1513         sh = get_active_stripe(conf, sector_nr, pd_idx, 1);
1514         if (sh == NULL) {
1515                 sh = get_active_stripe(conf, sector_nr, pd_idx, 0);
1516                 /* make sure we don't swamp the stripe cache if someone else
1517                  * is trying to get access
1518                  */
1519                 set_current_state(TASK_UNINTERRUPTIBLE);
1520                 schedule_timeout(1);
1521         }
1522         spin_lock(&sh->lock);
1523         set_bit(STRIPE_SYNCING, &sh->state);
1524         clear_bit(STRIPE_INSYNC, &sh->state);
1525         spin_unlock(&sh->lock);
1526
1527         handle_stripe(sh);
1528         release_stripe(sh);
1529
1530         return STRIPE_SECTORS;
1531 }
1532
1533 /*
1534  * This is our raid5 kernel thread.
1535  *
1536  * We scan the hash table for stripes which can be handled now.
1537  * During the scan, completed stripes are saved for us by the interrupt
1538  * handler, so that they will not have to wait for our next wakeup.
1539  */
1540 static void raid5d (mddev_t *mddev)
1541 {
1542         struct stripe_head *sh;
1543         raid5_conf_t *conf = mddev_to_conf(mddev);
1544         int handled;
1545
1546         PRINTK("+++ raid5d active\n");
1547
1548         md_check_recovery(mddev);
1549         md_handle_safemode(mddev);
1550
1551         handled = 0;
1552         spin_lock_irq(&conf->device_lock);
1553         while (1) {
1554                 struct list_head *first;
1555
1556                 if (list_empty(&conf->handle_list) &&
1557                     atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
1558                     !blk_queue_plugged(mddev->queue) &&
1559                     !list_empty(&conf->delayed_list))
1560                         raid5_activate_delayed(conf);
1561
1562                 if (list_empty(&conf->handle_list))
1563                         break;
1564
1565                 first = conf->handle_list.next;
1566                 sh = list_entry(first, struct stripe_head, lru);
1567
1568                 list_del_init(first);
1569                 atomic_inc(&sh->count);
1570                 if (atomic_read(&sh->count)!= 1)
1571                         BUG();
1572                 spin_unlock_irq(&conf->device_lock);
1573
1574                 handled++;
1575                 handle_stripe(sh);
1576                 release_stripe(sh);
1577
1578                 spin_lock_irq(&conf->device_lock);
1579         }
1580         PRINTK("%d stripes handled\n", handled);
1581
1582         spin_unlock_irq(&conf->device_lock);
1583
1584         unplug_slaves(mddev);
1585
1586         PRINTK("--- raid5d inactive\n");
1587 }
1588
1589 static int run (mddev_t *mddev)
1590 {
1591         raid5_conf_t *conf;
1592         int raid_disk, memory;
1593         mdk_rdev_t *rdev;
1594         struct disk_info *disk;
1595         struct list_head *tmp;
1596
1597         if (mddev->level != 5 && mddev->level != 4) {
1598                 printk("raid5: %s: raid level not set to 4/5 (%d)\n", mdname(mddev), mddev->level);
1599                 return -EIO;
1600         }
1601
1602         mddev->private = kmalloc (sizeof (raid5_conf_t)
1603                                   + mddev->raid_disks * sizeof(struct disk_info),
1604                                   GFP_KERNEL);
1605         if ((conf = mddev->private) == NULL)
1606                 goto abort;
1607         memset (conf, 0, sizeof (*conf) + mddev->raid_disks * sizeof(struct disk_info) );
1608         conf->mddev = mddev;
1609
1610         if ((conf->stripe_hashtbl = (struct stripe_head **) __get_free_pages(GFP_ATOMIC, HASH_PAGES_ORDER)) == NULL)
1611                 goto abort;
1612         memset(conf->stripe_hashtbl, 0, HASH_PAGES * PAGE_SIZE);
1613
1614         spin_lock_init(&conf->device_lock);
1615         init_waitqueue_head(&conf->wait_for_stripe);
1616         init_waitqueue_head(&conf->wait_for_overlap);
1617         INIT_LIST_HEAD(&conf->handle_list);
1618         INIT_LIST_HEAD(&conf->delayed_list);
1619         INIT_LIST_HEAD(&conf->inactive_list);
1620         atomic_set(&conf->active_stripes, 0);
1621         atomic_set(&conf->preread_active_stripes, 0);
1622
1623         PRINTK("raid5: run(%s) called.\n", mdname(mddev));
1624
1625         ITERATE_RDEV(mddev,rdev,tmp) {
1626                 raid_disk = rdev->raid_disk;
1627                 if (raid_disk >= mddev->raid_disks
1628                     || raid_disk < 0)
1629                         continue;
1630                 disk = conf->disks + raid_disk;
1631
1632                 disk->rdev = rdev;
1633
1634                 if (rdev->in_sync) {
1635                         char b[BDEVNAME_SIZE];
1636                         printk(KERN_INFO "raid5: device %s operational as raid"
1637                                 " disk %d\n", bdevname(rdev->bdev,b),
1638                                 raid_disk);
1639                         conf->working_disks++;
1640                 }
1641         }
1642
1643         conf->raid_disks = mddev->raid_disks;
1644         /*
1645          * 0 for a fully functional array, 1 for a degraded array.
1646          */
1647         mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks;
1648         conf->mddev = mddev;
1649         conf->chunk_size = mddev->chunk_size;
1650         conf->level = mddev->level;
1651         conf->algorithm = mddev->layout;
1652         conf->max_nr_stripes = NR_STRIPES;
1653
1654         /* device size must be a multiple of chunk size */
1655         mddev->size &= ~(mddev->chunk_size/1024 -1);
1656
1657         if (!conf->chunk_size || conf->chunk_size % 4) {
1658                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
1659                         conf->chunk_size, mdname(mddev));
1660                 goto abort;
1661         }
1662         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
1663                 printk(KERN_ERR
1664                         "raid5: unsupported parity algorithm %d for %s\n",
1665                         conf->algorithm, mdname(mddev));
1666                 goto abort;
1667         }
1668         if (mddev->degraded > 1) {
1669                 printk(KERN_ERR "raid5: not enough operational devices for %s"
1670                         " (%d/%d failed)\n",
1671                         mdname(mddev), conf->failed_disks, conf->raid_disks);
1672                 goto abort;
1673         }
1674
1675         if (mddev->degraded == 1 &&
1676             mddev->recovery_cp != MaxSector) {
1677                 printk(KERN_ERR
1678                         "raid5: cannot start dirty degraded array for %s\n",
1679                         mdname(mddev));
1680                 goto abort;
1681         }
1682
1683         {
1684                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
1685                 if (!mddev->thread) {
1686                         printk(KERN_ERR
1687                                 "raid5: couldn't allocate thread for %s\n",
1688                                 mdname(mddev));
1689                         goto abort;
1690                 }
1691         }
1692 memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
1693                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
1694         if (grow_stripes(conf, conf->max_nr_stripes)) {
1695                 printk(KERN_ERR
1696                         "raid5: couldn't allocate %dkB for buffers\n", memory);
1697                 shrink_stripes(conf);
1698                 md_unregister_thread(mddev->thread);
1699                 goto abort;
1700         } else
1701                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
1702                         memory, mdname(mddev));
1703
1704         if (mddev->degraded == 0)
1705                 printk("raid5: raid level %d set %s active with %d out of %d"
1706                         " devices, algorithm %d\n", conf->level, mdname(mddev),
1707                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
1708                         conf->algorithm);
1709         else
1710                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
1711                         " out of %d devices, algorithm %d\n", conf->level,
1712                         mdname(mddev), mddev->raid_disks - mddev->degraded,
1713                         mddev->raid_disks, conf->algorithm);
1714
1715         print_raid5_conf(conf);
1716
1717         /* read-ahead size must cover two whole stripes, which is
1718          * 2 * (n-1) * chunksize where 'n' is the number of raid devices
1719          */
1720         {
1721                 int stripe = (mddev->raid_disks-1) * mddev->chunk_size
1722                         / PAGE_CACHE_SIZE;
1723                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
1724                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
1725         }
1726
1727         /* Ok, everything is just fine now */
1728
1729         mddev->queue->unplug_fn = raid5_unplug_device;
1730         mddev->queue->issue_flush_fn = raid5_issue_flush;
1731
1732         mddev->array_size =  mddev->size * (mddev->raid_disks - 1);
1733         return 0;
1734 abort:
1735         if (conf) {
1736                 print_raid5_conf(conf);
1737                 if (conf->stripe_hashtbl)
1738                         free_pages((unsigned long) conf->stripe_hashtbl,
1739                                                         HASH_PAGES_ORDER);
1740                 kfree(conf);
1741         }
1742         mddev->private = NULL;
1743         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
1744         return -EIO;
1745 }
1746
1747
1748
1749 static int stop (mddev_t *mddev)
1750 {
1751         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1752
1753         md_unregister_thread(mddev->thread);
1754         mddev->thread = NULL;
1755         shrink_stripes(conf);
1756         free_pages((unsigned long) conf->stripe_hashtbl, HASH_PAGES_ORDER);
1757         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
1758         kfree(conf);
1759         mddev->private = NULL;
1760         return 0;
1761 }
1762
1763 #if RAID5_DEBUG
1764 static void print_sh (struct stripe_head *sh)
1765 {
1766         int i;
1767
1768         printk("sh %llu, pd_idx %d, state %ld.\n",
1769                 (unsigned long long)sh->sector, sh->pd_idx, sh->state);
1770         printk("sh %llu,  count %d.\n",
1771                 (unsigned long long)sh->sector, atomic_read(&sh->count));
1772         printk("sh %llu, ", (unsigned long long)sh->sector);
1773         for (i = 0; i < sh->raid_conf->raid_disks; i++) {
1774                 printk("(cache%d: %p %ld) ",
1775                         i, sh->dev[i].page, sh->dev[i].flags);
1776         }
1777         printk("\n");
1778 }
1779
1780 static void printall (raid5_conf_t *conf)
1781 {
1782         struct stripe_head *sh;
1783         int i;
1784
1785         spin_lock_irq(&conf->device_lock);
1786         for (i = 0; i < NR_HASH; i++) {
1787                 sh = conf->stripe_hashtbl[i];
1788                 for (; sh; sh = sh->hash_next) {
1789                         if (sh->raid_conf != conf)
1790                                 continue;
1791                         print_sh(sh);
1792                 }
1793         }
1794         spin_unlock_irq(&conf->device_lock);
1795 }
1796 #endif
1797
1798 static void status (struct seq_file *seq, mddev_t *mddev)
1799 {
1800         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1801         int i;
1802
1803         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
1804         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->working_disks);
1805         for (i = 0; i < conf->raid_disks; i++)
1806                 seq_printf (seq, "%s",
1807                                conf->disks[i].rdev &&
1808                                conf->disks[i].rdev->in_sync ? "U" : "_");
1809         seq_printf (seq, "]");
1810 #if RAID5_DEBUG
1811 #define D(x) \
1812         seq_printf (seq, "<"#x":%d>", atomic_read(&conf->x))
1813         printall(conf);
1814 #endif
1815 }
1816
1817 static void print_raid5_conf (raid5_conf_t *conf)
1818 {
1819         int i;
1820         struct disk_info *tmp;
1821
1822         printk("RAID5 conf printout:\n");
1823         if (!conf) {
1824                 printk("(conf==NULL)\n");
1825                 return;
1826         }
1827         printk(" --- rd:%d wd:%d fd:%d\n", conf->raid_disks,
1828                  conf->working_disks, conf->failed_disks);
1829
1830         for (i = 0; i < conf->raid_disks; i++) {
1831                 char b[BDEVNAME_SIZE];
1832                 tmp = conf->disks + i;
1833                 if (tmp->rdev)
1834                 printk(" disk %d, o:%d, dev:%s\n",
1835                         i, !tmp->rdev->faulty,
1836                         bdevname(tmp->rdev->bdev,b));
1837         }
1838 }
1839
1840 static int raid5_spare_active(mddev_t *mddev)
1841 {
1842         int i;
1843         raid5_conf_t *conf = mddev->private;
1844         struct disk_info *tmp;
1845
1846         for (i = 0; i < conf->raid_disks; i++) {
1847                 tmp = conf->disks + i;
1848                 if (tmp->rdev
1849                     && !tmp->rdev->faulty
1850                     && !tmp->rdev->in_sync) {
1851                         mddev->degraded--;
1852                         conf->failed_disks--;
1853                         conf->working_disks++;
1854                         tmp->rdev->in_sync = 1;
1855                 }
1856         }
1857         print_raid5_conf(conf);
1858         return 0;
1859 }
1860
1861 static int raid5_remove_disk(mddev_t *mddev, int number)
1862 {
1863         raid5_conf_t *conf = mddev->private;
1864         int err = 0;
1865         mdk_rdev_t *rdev;
1866         struct disk_info *p = conf->disks + number;
1867
1868         print_raid5_conf(conf);
1869         rdev = p->rdev;
1870         if (rdev) {
1871                 if (rdev->in_sync ||
1872                     atomic_read(&rdev->nr_pending)) {
1873                         err = -EBUSY;
1874                         goto abort;
1875                 }
1876                 p->rdev = NULL;
1877                 synchronize_rcu();
1878                 if (atomic_read(&rdev->nr_pending)) {
1879                         /* lost the race, try later */
1880                         err = -EBUSY;
1881                         p->rdev = rdev;
1882                 }
1883         }
1884 abort:
1885
1886         print_raid5_conf(conf);
1887         return err;
1888 }
1889
1890 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1891 {
1892         raid5_conf_t *conf = mddev->private;
1893         int found = 0;
1894         int disk;
1895         struct disk_info *p;
1896
1897         if (mddev->degraded > 1)
1898                 /* no point adding a device */
1899                 return 0;
1900
1901         /*
1902          * find the disk ...
1903          */
1904         for (disk=0; disk < mddev->raid_disks; disk++)
1905                 if ((p=conf->disks + disk)->rdev == NULL) {
1906                         rdev->in_sync = 0;
1907                         rdev->raid_disk = disk;
1908                         found = 1;
1909                         p->rdev = rdev;
1910                         break;
1911                 }
1912         print_raid5_conf(conf);
1913         return found;
1914 }
1915
1916 static int raid5_resize(mddev_t *mddev, sector_t sectors)
1917 {
1918         /* no resync is happening, and there is enough space
1919          * on all devices, so we can resize.
1920          * We need to make sure resync covers any new space.
1921          * If the array is shrinking we should possibly wait until
1922          * any io in the removed space completes, but it hardly seems
1923          * worth it.
1924          */
1925         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
1926         mddev->array_size = (sectors * (mddev->raid_disks-1))>>1;
1927         set_capacity(mddev->gendisk, mddev->array_size << 1);
1928         mddev->changed = 1;
1929         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
1930                 mddev->recovery_cp = mddev->size << 1;
1931                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
1932         }
1933         mddev->size = sectors /2;
1934         return 0;
1935 }
1936
1937 static mdk_personality_t raid5_personality=
1938 {
1939         .name           = "raid5",
1940         .owner          = THIS_MODULE,
1941         .make_request   = make_request,
1942         .run            = run,
1943         .stop           = stop,
1944         .status         = status,
1945         .error_handler  = error,
1946         .hot_add_disk   = raid5_add_disk,
1947         .hot_remove_disk= raid5_remove_disk,
1948         .spare_active   = raid5_spare_active,
1949         .sync_request   = sync_request,
1950         .resize         = raid5_resize,
1951 };
1952
1953 static int __init raid5_init (void)
1954 {
1955         return register_md_personality (RAID5, &raid5_personality);
1956 }
1957
1958 static void raid5_exit (void)
1959 {
1960         unregister_md_personality (RAID5);
1961 }
1962
1963 module_init(raid5_init);
1964 module_exit(raid5_exit);
1965 MODULE_LICENSE("GPL");
1966 MODULE_ALIAS("md-personality-4"); /* RAID5 */