err.no Git - linux-2.6/blob - 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  * BITMAP UNPLUGGING:
  23  *
  24  * The sequencing for updating the bitmap reliably is a little
  25  * subtle (and I got it wrong the first time) so it deserves some
  26  * explanation.
  27  *
  28  * We group bitmap updates into batches.  Each batch has a number.
  29  * We may write out several batches at once, but that isn't very important.
  30  * conf->bm_write is the number of the last batch successfully written.
  31  * conf->bm_flush is the number of the last batch that was closed to
  32  *    new additions.
  33  * When we discover that we will need to write to any block in a stripe
  34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35  * the number of the batch it will be in. This is bm_flush+1.
  36  * When we are ready to do a write, if that batch hasn't been written yet,
  37  *   we plug the array and queue the stripe for later.
  38  * When an unplug happens, we increment bm_flush, thus closing the current
  39  *   batch.
  40  * When we notice that bm_flush > bm_write, we write out all pending updates
  41  * to the bitmap, and advance bm_write to where bm_flush was.
  42  * This may occasionally write a bit out twice, but is sure never to
  43  * miss any bits.
  44  */
  45
  46 #include <linux/module.h>
  47 #include <linux/slab.h>
  48 #include <linux/highmem.h>
  49 #include <linux/bitops.h>
  50 #include <linux/kthread.h>
  51 #include <asm/atomic.h>
  52 #include "raid6.h"
  53
  54 #include <linux/raid/bitmap.h>
  55 #include <linux/async_tx.h>
  56
  57 /*
  58  * Stripe cache
  59  */
  60
  61 #define NR_STRIPES              256
  62 #define STRIPE_SIZE             PAGE_SIZE
  63 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  64 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  65 #define IO_THRESHOLD            1
  66 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  67 #define HASH_MASK               (NR_HASH - 1)
  68
  69 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
  70
  71 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
  72  * order without overlap.  There may be several bio's per stripe+device, and
  73  * a bio could span several devices.
  74  * When walking this list for a particular stripe+device, we must never proceed
  75  * beyond a bio that extends past this device, as the next bio might no longer
  76  * be valid.
  77  * This macro is used to determine the 'next' bio in the list, given the sector
  78  * of the current stripe+device
  79  */
  80 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
  81 /*
  82  * The following can be used to debug the driver
  83  */
  84 #define RAID5_PARANOIA  1
  85 #if RAID5_PARANOIA && defined(CONFIG_SMP)
  86 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
  87 #else
  88 # define CHECK_DEVLOCK()
  89 #endif
  90
  91 #ifdef DEBUG
  92 #define inline
  93 #define __inline__
  94 #endif
  95
  96 #if !RAID6_USE_EMPTY_ZERO_PAGE
  97 /* In .bss so it's zeroed */
  98 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
  99 #endif
 100
 101 static inline int raid6_next_disk(int disk, int raid_disks)
 102 {
 103         disk++;
 104         return (disk < raid_disks) ? disk : 0;
 105 }
 106
 107 static void return_io(struct bio *return_bi)
 108 {
 109         struct bio *bi = return_bi;
 110         while (bi) {
 111                 int bytes = bi->bi_size;
 112
 113                 return_bi = bi->bi_next;
 114                 bi->bi_next = NULL;
 115                 bi->bi_size = 0;
 116                 bi->bi_end_io(bi, bytes,
 117                               test_bit(BIO_UPTODATE, &bi->bi_flags)
 118                                 ? 0 : -EIO);
 119                 bi = return_bi;
 120         }
 121 }
 122
 123 static void print_raid5_conf (raid5_conf_t *conf);
 124
 125 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
 126 {
 127         if (atomic_dec_and_test(&sh->count)) {
 128                 BUG_ON(!list_empty(&sh->lru));
 129                 BUG_ON(atomic_read(&conf->active_stripes)==0);
 130                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
 131                         if (test_bit(STRIPE_DELAYED, &sh->state)) {
 132                                 list_add_tail(&sh->lru, &conf->delayed_list);
 133                                 blk_plug_device(conf->mddev->queue);
 134                         } else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 135                                    sh->bm_seq - conf->seq_write > 0) {
 136                                 list_add_tail(&sh->lru, &conf->bitmap_list);
 137                                 blk_plug_device(conf->mddev->queue);
 138                         } else {
 139                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
 140                                 list_add_tail(&sh->lru, &conf->handle_list);
 141                         }
 142                         md_wakeup_thread(conf->mddev->thread);
 143                 } else {
 144                         BUG_ON(sh->ops.pending);
 145                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
 146                                 atomic_dec(&conf->preread_active_stripes);
 147                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
 148                                         md_wakeup_thread(conf->mddev->thread);
 149                         }
 150                         atomic_dec(&conf->active_stripes);
 151                         if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 152                                 list_add_tail(&sh->lru, &conf->inactive_list);
 153                                 wake_up(&conf->wait_for_stripe);
 154                                 if (conf->retry_read_aligned)
 155                                         md_wakeup_thread(conf->mddev->thread);
 156                         }
 157                 }
 158         }
 159 }
 160 static void release_stripe(struct stripe_head *sh)
 161 {
 162         raid5_conf_t *conf = sh->raid_conf;
 163         unsigned long flags;
 164
 165         spin_lock_irqsave(&conf->device_lock, flags);
 166         __release_stripe(conf, sh);
 167         spin_unlock_irqrestore(&conf->device_lock, flags);
 168 }
 169
 170 static inline void remove_hash(struct stripe_head *sh)
 171 {
 172         pr_debug("remove_hash(), stripe %llu\n",
 173                 (unsigned long long)sh->sector);
 174
 175         hlist_del_init(&sh->hash);
 176 }
 177
 178 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
 179 {
 180         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 181
 182         pr_debug("insert_hash(), stripe %llu\n",
 183                 (unsigned long long)sh->sector);
 184
 185         CHECK_DEVLOCK();
 186         hlist_add_head(&sh->hash, hp);
 187 }
 188
 189
 190 /* find an idle stripe, make sure it is unhashed, and return it. */
 191 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
 192 {
 193         struct stripe_head *sh = NULL;
 194         struct list_head *first;
 195
 196         CHECK_DEVLOCK();
 197         if (list_empty(&conf->inactive_list))
 198                 goto out;
 199         first = conf->inactive_list.next;
 200         sh = list_entry(first, struct stripe_head, lru);
 201         list_del_init(first);
 202         remove_hash(sh);
 203         atomic_inc(&conf->active_stripes);
 204 out:
 205         return sh;
 206 }
 207
 208 static void shrink_buffers(struct stripe_head *sh, int num)
 209 {
 210         struct page *p;
 211         int i;
 212
 213         for (i=0; i<num ; i++) {
 214                 p = sh->dev[i].page;
 215                 if (!p)
 216                         continue;
 217                 sh->dev[i].page = NULL;
 218                 put_page(p);
 219         }
 220 }
 221
 222 static int grow_buffers(struct stripe_head *sh, int num)
 223 {
 224         int i;
 225
 226         for (i=0; i<num; i++) {
 227                 struct page *page;
 228
 229                 if (!(page = alloc_page(GFP_KERNEL))) {
 230                         return 1;
 231                 }
 232                 sh->dev[i].page = page;
 233         }
 234         return 0;
 235 }
 236
 237 static void raid5_build_block (struct stripe_head *sh, int i);
 238
 239 static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
 240 {
 241         raid5_conf_t *conf = sh->raid_conf;
 242         int i;
 243
 244         BUG_ON(atomic_read(&sh->count) != 0);
 245         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 246         BUG_ON(sh->ops.pending || sh->ops.ack || sh->ops.complete);
 247
 248         CHECK_DEVLOCK();
 249         pr_debug("init_stripe called, stripe %llu\n",
 250                 (unsigned long long)sh->sector);
 251
 252         remove_hash(sh);
 253
 254         sh->sector = sector;
 255         sh->pd_idx = pd_idx;
 256         sh->state = 0;
 257
 258         sh->disks = disks;
 259
 260         for (i = sh->disks; i--; ) {
 261                 struct r5dev *dev = &sh->dev[i];
 262
 263                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 264                     test_bit(R5_LOCKED, &dev->flags)) {
 265                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 266                                (unsigned long long)sh->sector, i, dev->toread,
 267                                dev->read, dev->towrite, dev->written,
 268                                test_bit(R5_LOCKED, &dev->flags));
 269                         BUG();
 270                 }
 271                 dev->flags = 0;
 272                 raid5_build_block(sh, i);
 273         }
 274         insert_hash(conf, sh);
 275 }
 276
 277 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
 278 {
 279         struct stripe_head *sh;
 280         struct hlist_node *hn;
 281
 282         CHECK_DEVLOCK();
 283         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 284         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
 285                 if (sh->sector == sector && sh->disks == disks)
 286                         return sh;
 287         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 288         return NULL;
 289 }
 290
 291 static void unplug_slaves(mddev_t *mddev);
 292 static void raid5_unplug_device(request_queue_t *q);
 293
 294 static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
 295                                              int pd_idx, int noblock)
 296 {
 297         struct stripe_head *sh;
 298
 299         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 300
 301         spin_lock_irq(&conf->device_lock);
 302
 303         do {
 304                 wait_event_lock_irq(conf->wait_for_stripe,
 305                                     conf->quiesce == 0,
 306                                     conf->device_lock, /* nothing */);
 307                 sh = __find_stripe(conf, sector, disks);
 308                 if (!sh) {
 309                         if (!conf->inactive_blocked)
 310                                 sh = get_free_stripe(conf);
 311                         if (noblock && sh == NULL)
 312                                 break;
 313                         if (!sh) {
 314                                 conf->inactive_blocked = 1;
 315                                 wait_event_lock_irq(conf->wait_for_stripe,
 316                                                     !list_empty(&conf->inactive_list) &&
 317                                                     (atomic_read(&conf->active_stripes)
 318                                                      < (conf->max_nr_stripes *3/4)
 319                                                      || !conf->inactive_blocked),
 320                                                     conf->device_lock,
 321                                                     raid5_unplug_device(conf->mddev->queue)
 322                                         );
 323                                 conf->inactive_blocked = 0;
 324                         } else
 325                                 init_stripe(sh, sector, pd_idx, disks);
 326                 } else {
 327                         if (atomic_read(&sh->count)) {
 328                           BUG_ON(!list_empty(&sh->lru));
 329                         } else {
 330                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 331                                         atomic_inc(&conf->active_stripes);
 332                                 if (list_empty(&sh->lru) &&
 333                                     !test_bit(STRIPE_EXPANDING, &sh->state))
 334                                         BUG();
 335                                 list_del_init(&sh->lru);
 336                         }
 337                 }
 338         } while (sh == NULL);
 339
 340         if (sh)
 341                 atomic_inc(&sh->count);
 342
 343         spin_unlock_irq(&conf->device_lock);
 344         return sh;
 345 }
 346
 347 /* test_and_ack_op() ensures that we only dequeue an operation once */
 348 #define test_and_ack_op(op, pend) \
 349 do {                                                    \
 350         if (test_bit(op, &sh->ops.pending) &&           \
 351                 !test_bit(op, &sh->ops.complete)) {     \
 352                 if (test_and_set_bit(op, &sh->ops.ack)) \
 353                         clear_bit(op, &pend);           \
 354                 else                                    \
 355                         ack++;                          \
 356         } else                                          \
 357                 clear_bit(op, &pend);                   \
 358 } while (0)
 359
 360 /* find new work to run, do not resubmit work that is already
 361  * in flight
 362  */
 363 static unsigned long get_stripe_work(struct stripe_head *sh)
 364 {
 365         unsigned long pending;
 366         int ack = 0;
 367
 368         pending = sh->ops.pending;
 369
 370         test_and_ack_op(STRIPE_OP_BIOFILL, pending);
 371         test_and_ack_op(STRIPE_OP_COMPUTE_BLK, pending);
 372         test_and_ack_op(STRIPE_OP_PREXOR, pending);
 373         test_and_ack_op(STRIPE_OP_BIODRAIN, pending);
 374         test_and_ack_op(STRIPE_OP_POSTXOR, pending);
 375         test_and_ack_op(STRIPE_OP_CHECK, pending);
 376         if (test_and_clear_bit(STRIPE_OP_IO, &sh->ops.pending))
 377                 ack++;
 378
 379         sh->ops.count -= ack;
 380         BUG_ON(sh->ops.count < 0);
 381
 382         return pending;
 383 }
 384
 385 static int
 386 raid5_end_read_request(struct bio *bi, unsigned int bytes_done, int error);
 387 static int
 388 raid5_end_write_request (struct bio *bi, unsigned int bytes_done, int error);
 389
 390 static void ops_run_io(struct stripe_head *sh)
 391 {
 392         raid5_conf_t *conf = sh->raid_conf;
 393         int i, disks = sh->disks;
 394
 395         might_sleep();
 396
 397         for (i = disks; i--; ) {
 398                 int rw;
 399                 struct bio *bi;
 400                 mdk_rdev_t *rdev;
 401                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
 402                         rw = WRITE;
 403                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 404                         rw = READ;
 405                 else
 406                         continue;
 407
 408                 bi = &sh->dev[i].req;
 409
 410                 bi->bi_rw = rw;
 411                 if (rw == WRITE)
 412                         bi->bi_end_io = raid5_end_write_request;
 413                 else
 414                         bi->bi_end_io = raid5_end_read_request;
 415
 416                 rcu_read_lock();
 417                 rdev = rcu_dereference(conf->disks[i].rdev);
 418                 if (rdev && test_bit(Faulty, &rdev->flags))
 419                         rdev = NULL;
 420                 if (rdev)
 421                         atomic_inc(&rdev->nr_pending);
 422                 rcu_read_unlock();
 423
 424                 if (rdev) {
 425                         if (test_bit(STRIPE_SYNCING, &sh->state) ||
 426                                 test_bit(STRIPE_EXPAND_SOURCE, &sh->state) ||
 427                                 test_bit(STRIPE_EXPAND_READY, &sh->state))
 428                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 429
 430                         bi->bi_bdev = rdev->bdev;
 431                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
 432                                 __FUNCTION__, (unsigned long long)sh->sector,
 433                                 bi->bi_rw, i);
 434                         atomic_inc(&sh->count);
 435                         bi->bi_sector = sh->sector + rdev->data_offset;
 436                         bi->bi_flags = 1 << BIO_UPTODATE;
 437                         bi->bi_vcnt = 1;
 438                         bi->bi_max_vecs = 1;
 439                         bi->bi_idx = 0;
 440                         bi->bi_io_vec = &sh->dev[i].vec;
 441                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 442                         bi->bi_io_vec[0].bv_offset = 0;
 443                         bi->bi_size = STRIPE_SIZE;
 444                         bi->bi_next = NULL;
 445                         if (rw == WRITE &&
 446                             test_bit(R5_ReWrite, &sh->dev[i].flags))
 447                                 atomic_add(STRIPE_SECTORS,
 448                                         &rdev->corrected_errors);
 449                         generic_make_request(bi);
 450                 } else {
 451                         if (rw == WRITE)
 452                                 set_bit(STRIPE_DEGRADED, &sh->state);
 453                         pr_debug("skip op %ld on disc %d for sector %llu\n",
 454                                 bi->bi_rw, i, (unsigned long long)sh->sector);
 455                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 456                         set_bit(STRIPE_HANDLE, &sh->state);
 457                 }
 458         }
 459 }
 460
 461 static struct dma_async_tx_descriptor *
 462 async_copy_data(int frombio, struct bio *bio, struct page *page,
 463         sector_t sector, struct dma_async_tx_descriptor *tx)
 464 {
 465         struct bio_vec *bvl;
 466         struct page *bio_page;
 467         int i;
 468         int page_offset;
 469
 470         if (bio->bi_sector >= sector)
 471                 page_offset = (signed)(bio->bi_sector - sector) * 512;
 472         else
 473                 page_offset = (signed)(sector - bio->bi_sector) * -512;
 474         bio_for_each_segment(bvl, bio, i) {
 475                 int len = bio_iovec_idx(bio, i)->bv_len;
 476                 int clen;
 477                 int b_offset = 0;
 478
 479                 if (page_offset < 0) {
 480                         b_offset = -page_offset;
 481                         page_offset += b_offset;
 482                         len -= b_offset;
 483                 }
 484
 485                 if (len > 0 && page_offset + len > STRIPE_SIZE)
 486                         clen = STRIPE_SIZE - page_offset;
 487                 else
 488                         clen = len;
 489
 490                 if (clen > 0) {
 491                         b_offset += bio_iovec_idx(bio, i)->bv_offset;
 492                         bio_page = bio_iovec_idx(bio, i)->bv_page;
 493                         if (frombio)
 494                                 tx = async_memcpy(page, bio_page, page_offset,
 495                                         b_offset, clen,
 496                                         ASYNC_TX_DEP_ACK | ASYNC_TX_KMAP_SRC,
 497                                         tx, NULL, NULL);
 498                         else
 499                                 tx = async_memcpy(bio_page, page, b_offset,
 500                                         page_offset, clen,
 501                                         ASYNC_TX_DEP_ACK | ASYNC_TX_KMAP_DST,
 502                                         tx, NULL, NULL);
 503                 }
 504                 if (clen < len) /* hit end of page */
 505                         break;
 506                 page_offset +=  len;
 507         }
 508
 509         return tx;
 510 }
 511
 512 static void ops_complete_biofill(void *stripe_head_ref)
 513 {
 514         struct stripe_head *sh = stripe_head_ref;
 515         struct bio *return_bi = NULL;
 516         raid5_conf_t *conf = sh->raid_conf;
 517         int i, more_to_read = 0;
 518
 519         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 520                 (unsigned long long)sh->sector);
 521
 522         /* clear completed biofills */
 523         for (i = sh->disks; i--; ) {
 524                 struct r5dev *dev = &sh->dev[i];
 525                 /* check if this stripe has new incoming reads */
 526                 if (dev->toread)
 527                         more_to_read++;
 528
 529                 /* acknowledge completion of a biofill operation */
 530                 /* and check if we need to reply to a read request
 531                 */
 532                 if (test_bit(R5_Wantfill, &dev->flags) && !dev->toread) {
 533                         struct bio *rbi, *rbi2;
 534                         clear_bit(R5_Wantfill, &dev->flags);
 535
 536                         /* The access to dev->read is outside of the
 537                          * spin_lock_irq(&conf->device_lock), but is protected
 538                          * by the STRIPE_OP_BIOFILL pending bit
 539                          */
 540                         BUG_ON(!dev->read);
 541                         rbi = dev->read;
 542                         dev->read = NULL;
 543                         while (rbi && rbi->bi_sector <
 544                                 dev->sector + STRIPE_SECTORS) {
 545                                 rbi2 = r5_next_bio(rbi, dev->sector);
 546                                 spin_lock_irq(&conf->device_lock);
 547                                 if (--rbi->bi_phys_segments == 0) {
 548                                         rbi->bi_next = return_bi;
 549                                         return_bi = rbi;
 550                                 }
 551                                 spin_unlock_irq(&conf->device_lock);
 552                                 rbi = rbi2;
 553                         }
 554                 }
 555         }
 556         clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
 557         clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
 558
 559         return_io(return_bi);
 560
 561         if (more_to_read)
 562                 set_bit(STRIPE_HANDLE, &sh->state);
 563         release_stripe(sh);
 564 }
 565
 566 static void ops_run_biofill(struct stripe_head *sh)
 567 {
 568         struct dma_async_tx_descriptor *tx = NULL;
 569         raid5_conf_t *conf = sh->raid_conf;
 570         int i;
 571
 572         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 573                 (unsigned long long)sh->sector);
 574
 575         for (i = sh->disks; i--; ) {
 576                 struct r5dev *dev = &sh->dev[i];
 577                 if (test_bit(R5_Wantfill, &dev->flags)) {
 578                         struct bio *rbi;
 579                         spin_lock_irq(&conf->device_lock);
 580                         dev->read = rbi = dev->toread;
 581                         dev->toread = NULL;
 582                         spin_unlock_irq(&conf->device_lock);
 583                         while (rbi && rbi->bi_sector <
 584                                 dev->sector + STRIPE_SECTORS) {
 585                                 tx = async_copy_data(0, rbi, dev->page,
 586                                         dev->sector, tx);
 587                                 rbi = r5_next_bio(rbi, dev->sector);
 588                         }
 589                 }
 590         }
 591
 592         atomic_inc(&sh->count);
 593         async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
 594                 ops_complete_biofill, sh);
 595 }
 596
 597 static void ops_complete_compute5(void *stripe_head_ref)
 598 {
 599         struct stripe_head *sh = stripe_head_ref;
 600         int target = sh->ops.target;
 601         struct r5dev *tgt = &sh->dev[target];
 602
 603         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 604                 (unsigned long long)sh->sector);
 605
 606         set_bit(R5_UPTODATE, &tgt->flags);
 607         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 608         clear_bit(R5_Wantcompute, &tgt->flags);
 609         set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
 610         set_bit(STRIPE_HANDLE, &sh->state);
 611         release_stripe(sh);
 612 }
 613
 614 static struct dma_async_tx_descriptor *
 615 ops_run_compute5(struct stripe_head *sh, unsigned long pending)
 616 {
 617         /* kernel stack size limits the total number of disks */
 618         int disks = sh->disks;
 619         struct page *xor_srcs[disks];
 620         int target = sh->ops.target;
 621         struct r5dev *tgt = &sh->dev[target];
 622         struct page *xor_dest = tgt->page;
 623         int count = 0;
 624         struct dma_async_tx_descriptor *tx;
 625         int i;
 626
 627         pr_debug("%s: stripe %llu block: %d\n",
 628                 __FUNCTION__, (unsigned long long)sh->sector, target);
 629         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
 630
 631         for (i = disks; i--; )
 632                 if (i != target)
 633                         xor_srcs[count++] = sh->dev[i].page;
 634
 635         atomic_inc(&sh->count);
 636
 637         if (unlikely(count == 1))
 638                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
 639                         0, NULL, ops_complete_compute5, sh);
 640         else
 641                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
 642                         ASYNC_TX_XOR_ZERO_DST, NULL,
 643                         ops_complete_compute5, sh);
 644
 645         /* ack now if postxor is not set to be run */
 646         if (tx && !test_bit(STRIPE_OP_POSTXOR, &pending))
 647                 async_tx_ack(tx);
 648
 649         return tx;
 650 }
 651
 652 static void ops_complete_prexor(void *stripe_head_ref)
 653 {
 654         struct stripe_head *sh = stripe_head_ref;
 655
 656         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 657                 (unsigned long long)sh->sector);
 658
 659         set_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
 660 }
 661
 662 static struct dma_async_tx_descriptor *
 663 ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 664 {
 665         /* kernel stack size limits the total number of disks */
 666         int disks = sh->disks;
 667         struct page *xor_srcs[disks];
 668         int count = 0, pd_idx = sh->pd_idx, i;
 669
 670         /* existing parity data subtracted */
 671         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
 672
 673         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 674                 (unsigned long long)sh->sector);
 675
 676         for (i = disks; i--; ) {
 677                 struct r5dev *dev = &sh->dev[i];
 678                 /* Only process blocks that are known to be uptodate */
 679                 if (dev->towrite && test_bit(R5_Wantprexor, &dev->flags))
 680                         xor_srcs[count++] = dev->page;
 681         }
 682
 683         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
 684                 ASYNC_TX_DEP_ACK | ASYNC_TX_XOR_DROP_DST, tx,
 685                 ops_complete_prexor, sh);
 686
 687         return tx;
 688 }
 689
 690 static struct dma_async_tx_descriptor *
 691 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 692 {
 693         int disks = sh->disks;
 694         int pd_idx = sh->pd_idx, i;
 695
 696         /* check if prexor is active which means only process blocks
 697          * that are part of a read-modify-write (Wantprexor)
 698          */
 699         int prexor = test_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
 700
 701         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 702                 (unsigned long long)sh->sector);
 703
 704         for (i = disks; i--; ) {
 705                 struct r5dev *dev = &sh->dev[i];
 706                 struct bio *chosen;
 707                 int towrite;
 708
 709                 towrite = 0;
 710                 if (prexor) { /* rmw */
 711                         if (dev->towrite &&
 712                             test_bit(R5_Wantprexor, &dev->flags))
 713                                 towrite = 1;
 714                 } else { /* rcw */
 715                         if (i != pd_idx && dev->towrite &&
 716                                 test_bit(R5_LOCKED, &dev->flags))
 717                                 towrite = 1;
 718                 }
 719
 720                 if (towrite) {
 721                         struct bio *wbi;
 722
 723                         spin_lock(&sh->lock);
 724                         chosen = dev->towrite;
 725                         dev->towrite = NULL;
 726                         BUG_ON(dev->written);
 727                         wbi = dev->written = chosen;
 728                         spin_unlock(&sh->lock);
 729
 730                         while (wbi && wbi->bi_sector <
 731                                 dev->sector + STRIPE_SECTORS) {
 732                                 tx = async_copy_data(1, wbi, dev->page,
 733                                         dev->sector, tx);
 734                                 wbi = r5_next_bio(wbi, dev->sector);
 735                         }
 736                 }
 737         }
 738
 739         return tx;
 740 }
 741
 742 static void ops_complete_postxor(void *stripe_head_ref)
 743 {
 744         struct stripe_head *sh = stripe_head_ref;
 745
 746         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 747                 (unsigned long long)sh->sector);
 748
 749         set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
 750         set_bit(STRIPE_HANDLE, &sh->state);
 751         release_stripe(sh);
 752 }
 753
 754 static void ops_complete_write(void *stripe_head_ref)
 755 {
 756         struct stripe_head *sh = stripe_head_ref;
 757         int disks = sh->disks, i, pd_idx = sh->pd_idx;
 758
 759         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 760                 (unsigned long long)sh->sector);
 761
 762         for (i = disks; i--; ) {
 763                 struct r5dev *dev = &sh->dev[i];
 764                 if (dev->written || i == pd_idx)
 765                         set_bit(R5_UPTODATE, &dev->flags);
 766         }
 767
 768         set_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
 769         set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
 770
 771         set_bit(STRIPE_HANDLE, &sh->state);
 772         release_stripe(sh);
 773 }
 774
 775 static void
 776 ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 777 {
 778         /* kernel stack size limits the total number of disks */
 779         int disks = sh->disks;
 780         struct page *xor_srcs[disks];
 781
 782         int count = 0, pd_idx = sh->pd_idx, i;
 783         struct page *xor_dest;
 784         int prexor = test_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
 785         unsigned long flags;
 786         dma_async_tx_callback callback;
 787
 788         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 789                 (unsigned long long)sh->sector);
 790
 791         /* check if prexor is active which means only process blocks
 792          * that are part of a read-modify-write (written)
 793          */
 794         if (prexor) {
 795                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
 796                 for (i = disks; i--; ) {
 797                         struct r5dev *dev = &sh->dev[i];
 798                         if (dev->written)
 799                                 xor_srcs[count++] = dev->page;
 800                 }
 801         } else {
 802                 xor_dest = sh->dev[pd_idx].page;
 803                 for (i = disks; i--; ) {
 804                         struct r5dev *dev = &sh->dev[i];
 805                         if (i != pd_idx)
 806                                 xor_srcs[count++] = dev->page;
 807                 }
 808         }
 809
 810         /* check whether this postxor is part of a write */
 811         callback = test_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending) ?
 812                 ops_complete_write : ops_complete_postxor;
 813
 814         /* 1/ if we prexor'd then the dest is reused as a source
 815          * 2/ if we did not prexor then we are redoing the parity
 816          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
 817          * for the synchronous xor case
 818          */
 819         flags = ASYNC_TX_DEP_ACK | ASYNC_TX_ACK |
 820                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
 821
 822         atomic_inc(&sh->count);
 823
 824         if (unlikely(count == 1)) {
 825                 flags &= ~(ASYNC_TX_XOR_DROP_DST | ASYNC_TX_XOR_ZERO_DST);
 826                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
 827                         flags, tx, callback, sh);
 828         } else
 829                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
 830                         flags, tx, callback, sh);
 831 }
 832
 833 static void ops_complete_check(void *stripe_head_ref)
 834 {
 835         struct stripe_head *sh = stripe_head_ref;
 836         int pd_idx = sh->pd_idx;
 837
 838         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 839                 (unsigned long long)sh->sector);
 840
 841         if (test_and_clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending) &&
 842                 sh->ops.zero_sum_result == 0)
 843                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
 844
 845         set_bit(STRIPE_OP_CHECK, &sh->ops.complete);
 846         set_bit(STRIPE_HANDLE, &sh->state);
 847         release_stripe(sh);
 848 }
 849
 850 static void ops_run_check(struct stripe_head *sh)
 851 {
 852         /* kernel stack size limits the total number of disks */
 853         int disks = sh->disks;
 854         struct page *xor_srcs[disks];
 855         struct dma_async_tx_descriptor *tx;
 856
 857         int count = 0, pd_idx = sh->pd_idx, i;
 858         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
 859
 860         pr_debug("%s: stripe %llu\n", __FUNCTION__,
 861                 (unsigned long long)sh->sector);
 862
 863         for (i = disks; i--; ) {
 864                 struct r5dev *dev = &sh->dev[i];
 865                 if (i != pd_idx)
 866                         xor_srcs[count++] = dev->page;
 867         }
 868
 869         tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
 870                 &sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
 871
 872         if (tx)
 873                 set_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
 874         else
 875                 clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
 876
 877         atomic_inc(&sh->count);
 878         tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
 879                 ops_complete_check, sh);
 880 }
 881
 882 static void raid5_run_ops(struct stripe_head *sh, unsigned long pending)
 883 {
 884         int overlap_clear = 0, i, disks = sh->disks;
 885         struct dma_async_tx_descriptor *tx = NULL;
 886
 887         if (test_bit(STRIPE_OP_BIOFILL, &pending)) {
 888                 ops_run_biofill(sh);
 889                 overlap_clear++;
 890         }
 891
 892         if (test_bit(STRIPE_OP_COMPUTE_BLK, &pending))
 893                 tx = ops_run_compute5(sh, pending);
 894
 895         if (test_bit(STRIPE_OP_PREXOR, &pending))
 896                 tx = ops_run_prexor(sh, tx);
 897
 898         if (test_bit(STRIPE_OP_BIODRAIN, &pending)) {
 899                 tx = ops_run_biodrain(sh, tx);
 900                 overlap_clear++;
 901         }
 902
 903         if (test_bit(STRIPE_OP_POSTXOR, &pending))
 904                 ops_run_postxor(sh, tx);
 905
 906         if (test_bit(STRIPE_OP_CHECK, &pending))
 907                 ops_run_check(sh);
 908
 909         if (test_bit(STRIPE_OP_IO, &pending))
 910                 ops_run_io(sh);
 911
 912         if (overlap_clear)
 913                 for (i = disks; i--; ) {
 914                         struct r5dev *dev = &sh->dev[i];
 915                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
 916                                 wake_up(&sh->raid_conf->wait_for_overlap);
 917                 }
 918 }
 919
 920 static int grow_one_stripe(raid5_conf_t *conf)
 921 {
 922         struct stripe_head *sh;
 923         sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
 924         if (!sh)
 925                 return 0;
 926         memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
 927         sh->raid_conf = conf;
 928         spin_lock_init(&sh->lock);
 929
 930         if (grow_buffers(sh, conf->raid_disks)) {
 931                 shrink_buffers(sh, conf->raid_disks);
 932                 kmem_cache_free(conf->slab_cache, sh);
 933                 return 0;
 934         }
 935         sh->disks = conf->raid_disks;
 936         /* we just created an active stripe so... */
 937         atomic_set(&sh->count, 1);
 938         atomic_inc(&conf->active_stripes);
 939         INIT_LIST_HEAD(&sh->lru);
 940         release_stripe(sh);
 941         return 1;
 942 }
 943
 944 static int grow_stripes(raid5_conf_t *conf, int num)
 945 {
 946         struct kmem_cache *sc;
 947         int devs = conf->raid_disks;
 948
 949         sprintf(conf->cache_name[0], "raid5-%s", mdname(conf->mddev));
 950         sprintf(conf->cache_name[1], "raid5-%s-alt", mdname(conf->mddev));
 951         conf->active_name = 0;
 952         sc = kmem_cache_create(conf->cache_name[conf->active_name],
 953                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
 954                                0, 0, NULL, NULL);
 955         if (!sc)
 956                 return 1;
 957         conf->slab_cache = sc;
 958         conf->pool_size = devs;
 959         while (num--)
 960                 if (!grow_one_stripe(conf))
 961                         return 1;
 962         return 0;
 963 }
 964
 965 #ifdef CONFIG_MD_RAID5_RESHAPE
 966 static int resize_stripes(raid5_conf_t *conf, int newsize)
 967 {
 968         /* Make all the stripes able to hold 'newsize' devices.
 969          * New slots in each stripe get 'page' set to a new page.
 970          *
 971          * This happens in stages:
 972          * 1/ create a new kmem_cache and allocate the required number of
 973          *    stripe_heads.
 974          * 2/ gather all the old stripe_heads and tranfer the pages across
 975          *    to the new stripe_heads.  This will have the side effect of
 976          *    freezing the array as once all stripe_heads have been collected,
 977          *    no IO will be possible.  Old stripe heads are freed once their
 978          *    pages have been transferred over, and the old kmem_cache is
 979          *    freed when all stripes are done.
 980          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
 981          *    we simple return a failre status - no need to clean anything up.
 982          * 4/ allocate new pages for the new slots in the new stripe_heads.
 983          *    If this fails, we don't bother trying the shrink the
 984          *    stripe_heads down again, we just leave them as they are.
 985          *    As each stripe_head is processed the new one is released into
 986          *    active service.
 987          *
 988          * Once step2 is started, we cannot afford to wait for a write,
 989          * so we use GFP_NOIO allocations.
 990          */
 991         struct stripe_head *osh, *nsh;
 992         LIST_HEAD(newstripes);
 993         struct disk_info *ndisks;
 994         int err = 0;
 995         struct kmem_cache *sc;
 996         int i;
 997
 998         if (newsize <= conf->pool_size)
 999                 return 0; /* never bother to shrink */
1000
1001         md_allow_write(conf->mddev);
1002
1003         /* Step 1 */
1004         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1005                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1006                                0, 0, NULL, NULL);
1007         if (!sc)
1008                 return -ENOMEM;
1009
1010         for (i = conf->max_nr_stripes; i; i--) {
1011                 nsh = kmem_cache_alloc(sc, GFP_KERNEL);
1012                 if (!nsh)
1013                         break;
1014
1015                 memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
1016
1017                 nsh->raid_conf = conf;
1018                 spin_lock_init(&nsh->lock);
1019
1020                 list_add(&nsh->lru, &newstripes);
1021         }
1022         if (i) {
1023                 /* didn't get enough, give up */
1024                 while (!list_empty(&newstripes)) {
1025                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
1026                         list_del(&nsh->lru);
1027                         kmem_cache_free(sc, nsh);
1028                 }
1029                 kmem_cache_destroy(sc);
1030                 return -ENOMEM;
1031         }
1032         /* Step 2 - Must use GFP_NOIO now.
1033          * OK, we have enough stripes, start collecting inactive
1034          * stripes and copying them over
1035          */
1036         list_for_each_entry(nsh, &newstripes, lru) {
1037                 spin_lock_irq(&conf->device_lock);
1038                 wait_event_lock_irq(conf->wait_for_stripe,
1039                                     !list_empty(&conf->inactive_list),
1040                                     conf->device_lock,
1041                                     unplug_slaves(conf->mddev)
1042                         );
1043                 osh = get_free_stripe(conf);
1044                 spin_unlock_irq(&conf->device_lock);
1045                 atomic_set(&nsh->count, 1);
1046                 for(i=0; i<conf->pool_size; i++)
1047                         nsh->dev[i].page = osh->dev[i].page;
1048                 for( ; i<newsize; i++)
1049                         nsh->dev[i].page = NULL;
1050                 kmem_cache_free(conf->slab_cache, osh);
1051         }
1052         kmem_cache_destroy(conf->slab_cache);
1053
1054         /* Step 3.
1055          * At this point, we are holding all the stripes so the array
1056          * is completely stalled, so now is a good time to resize
1057          * conf->disks.
1058          */
1059         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1060         if (ndisks) {
1061                 for (i=0; i<conf->raid_disks; i++)
1062                         ndisks[i] = conf->disks[i];
1063                 kfree(conf->disks);
1064                 conf->disks = ndisks;
1065         } else
1066                 err = -ENOMEM;
1067
1068         /* Step 4, return new stripes to service */
1069         while(!list_empty(&newstripes)) {
1070                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1071                 list_del_init(&nsh->lru);
1072                 for (i=conf->raid_disks; i < newsize; i++)
1073                         if (nsh->dev[i].page == NULL) {
1074                                 struct page *p = alloc_page(GFP_NOIO);
1075                                 nsh->dev[i].page = p;
1076                                 if (!p)
1077                                         err = -ENOMEM;
1078                         }
1079                 release_stripe(nsh);
1080         }
1081         /* critical section pass, GFP_NOIO no longer needed */
1082
1083         conf->slab_cache = sc;
1084         conf->active_name = 1-conf->active_name;
1085         conf->pool_size = newsize;
1086         return err;
1087 }
1088 #endif
1089
1090 static int drop_one_stripe(raid5_conf_t *conf)
1091 {
1092         struct stripe_head *sh;
1093
1094         spin_lock_irq(&conf->device_lock);
1095         sh = get_free_stripe(conf);
1096         spin_unlock_irq(&conf->device_lock);
1097         if (!sh)
1098                 return 0;
1099         BUG_ON(atomic_read(&sh->count));
1100         shrink_buffers(sh, conf->pool_size);
1101         kmem_cache_free(conf->slab_cache, sh);
1102         atomic_dec(&conf->active_stripes);
1103         return 1;
1104 }
1105
1106 static void shrink_stripes(raid5_conf_t *conf)
1107 {
1108         while (drop_one_stripe(conf))
1109                 ;
1110
1111         if (conf->slab_cache)
1112                 kmem_cache_destroy(conf->slab_cache);
1113         conf->slab_cache = NULL;
1114 }
1115
1116 static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done,
1117                                    int error)
1118 {
1119         struct stripe_head *sh = bi->bi_private;
1120         raid5_conf_t *conf = sh->raid_conf;
1121         int disks = sh->disks, i;
1122         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1123         char b[BDEVNAME_SIZE];
1124         mdk_rdev_t *rdev;
1125
1126         if (bi->bi_size)
1127                 return 1;
1128
1129         for (i=0 ; i<disks; i++)
1130                 if (bi == &sh->dev[i].req)
1131                         break;
1132
1133         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1134                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1135                 uptodate);
1136         if (i == disks) {
1137                 BUG();
1138                 return 0;
1139         }
1140
1141         if (uptodate) {
1142                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
1143                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1144                         rdev = conf->disks[i].rdev;
1145                         printk(KERN_INFO "raid5:%s: read error corrected (%lu sectors at %llu on %s)\n",
1146                                mdname(conf->mddev), STRIPE_SECTORS,
1147                                (unsigned long long)sh->sector + rdev->data_offset,
1148                                bdevname(rdev->bdev, b));
1149                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1150                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1151                 }
1152                 if (atomic_read(&conf->disks[i].rdev->read_errors))
1153                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
1154         } else {
1155                 const char *bdn = bdevname(conf->disks[i].rdev->bdev, b);
1156                 int retry = 0;
1157                 rdev = conf->disks[i].rdev;
1158
1159                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1160                 atomic_inc(&rdev->read_errors);
1161                 if (conf->mddev->degraded)
1162                         printk(KERN_WARNING "raid5:%s: read error not correctable (sector %llu on %s).\n",
1163                                mdname(conf->mddev),
1164                                (unsigned long long)sh->sector + rdev->data_offset,
1165                                bdn);
1166                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
1167                         /* Oh, no!!! */
1168                         printk(KERN_WARNING "raid5:%s: read error NOT corrected!! (sector %llu on %s).\n",
1169                                mdname(conf->mddev),
1170                                (unsigned long long)sh->sector + rdev->data_offset,
1171                                bdn);
1172                 else if (atomic_read(&rdev->read_errors)
1173                          > conf->max_nr_stripes)
1174                         printk(KERN_WARNING
1175                                "raid5:%s: Too many read errors, failing device %s.\n",
1176                                mdname(conf->mddev), bdn);
1177                 else
1178                         retry = 1;
1179                 if (retry)
1180                         set_bit(R5_ReadError, &sh->dev[i].flags);
1181                 else {
1182                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1183                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1184                         md_error(conf->mddev, rdev);
1185                 }
1186         }
1187         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1188         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1189         set_bit(STRIPE_HANDLE, &sh->state);
1190         release_stripe(sh);
1191         return 0;
1192 }
1193
1194 static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
1195                                     int error)
1196 {
1197         struct stripe_head *sh = bi->bi_private;
1198         raid5_conf_t *conf = sh->raid_conf;
1199         int disks = sh->disks, i;
1200         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1201
1202         if (bi->bi_size)
1203                 return 1;
1204
1205         for (i=0 ; i<disks; i++)
1206                 if (bi == &sh->dev[i].req)
1207                         break;
1208
1209         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1210                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1211                 uptodate);
1212         if (i == disks) {
1213                 BUG();
1214                 return 0;
1215         }
1216
1217         if (!uptodate)
1218                 md_error(conf->mddev, conf->disks[i].rdev);
1219
1220         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1221
1222         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1223         set_bit(STRIPE_HANDLE, &sh->state);
1224         release_stripe(sh);
1225         return 0;
1226 }
1227
1228
1229 static sector_t compute_blocknr(struct stripe_head *sh, int i);
1230
1231 static void raid5_build_block (struct stripe_head *sh, int i)
1232 {
1233         struct r5dev *dev = &sh->dev[i];
1234
1235         bio_init(&dev->req);
1236         dev->req.bi_io_vec = &dev->vec;
1237         dev->req.bi_vcnt++;
1238         dev->req.bi_max_vecs++;
1239         dev->vec.bv_page = dev->page;
1240         dev->vec.bv_len = STRIPE_SIZE;
1241         dev->vec.bv_offset = 0;
1242
1243         dev->req.bi_sector = sh->sector;
1244         dev->req.bi_private = sh;
1245
1246         dev->flags = 0;
1247         dev->sector = compute_blocknr(sh, i);
1248 }
1249
1250 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1251 {
1252         char b[BDEVNAME_SIZE];
1253         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
1254         pr_debug("raid5: error called\n");
1255
1256         if (!test_bit(Faulty, &rdev->flags)) {
1257                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
1258                 if (test_and_clear_bit(In_sync, &rdev->flags)) {
1259                         unsigned long flags;
1260                         spin_lock_irqsave(&conf->device_lock, flags);
1261                         mddev->degraded++;
1262                         spin_unlock_irqrestore(&conf->device_lock, flags);
1263                         /*
1264                          * if recovery was running, make sure it aborts.
1265                          */
1266                         set_bit(MD_RECOVERY_ERR, &mddev->recovery);
1267                 }
1268                 set_bit(Faulty, &rdev->flags);
1269                 printk (KERN_ALERT
1270                         "raid5: Disk failure on %s, disabling device."
1271                         " Operation continuing on %d devices\n",
1272                         bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
1273         }
1274 }
1275
1276 /*
1277  * Input: a 'big' sector number,
1278  * Output: index of the data and parity disk, and the sector # in them.
1279  */
1280 static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
1281                         unsigned int data_disks, unsigned int * dd_idx,
1282                         unsigned int * pd_idx, raid5_conf_t *conf)
1283 {
1284         long stripe;
1285         unsigned long chunk_number;
1286         unsigned int chunk_offset;
1287         sector_t new_sector;
1288         int sectors_per_chunk = conf->chunk_size >> 9;
1289
1290         /* First compute the information on this sector */
1291
1292         /*
1293          * Compute the chunk number and the sector offset inside the chunk
1294          */
1295         chunk_offset = sector_div(r_sector, sectors_per_chunk);
1296         chunk_number = r_sector;
1297         BUG_ON(r_sector != chunk_number);
1298
1299         /*
1300          * Compute the stripe number
1301          */
1302         stripe = chunk_number / data_disks;
1303
1304         /*
1305          * Compute the data disk and parity disk indexes inside the stripe
1306          */
1307         *dd_idx = chunk_number % data_disks;
1308
1309         /*
1310          * Select the parity disk based on the user selected algorithm.
1311          */
1312         switch(conf->level) {
1313         case 4:
1314                 *pd_idx = data_disks;
1315                 break;
1316         case 5:
1317                 switch (conf->algorithm) {
1318                 case ALGORITHM_LEFT_ASYMMETRIC:
1319                         *pd_idx = data_disks - stripe % raid_disks;
1320                         if (*dd_idx >= *pd_idx)
1321                                 (*dd_idx)++;
1322                         break;
1323                 case ALGORITHM_RIGHT_ASYMMETRIC:
1324                         *pd_idx = stripe % raid_disks;
1325                         if (*dd_idx >= *pd_idx)
1326                                 (*dd_idx)++;
1327                         break;
1328                 case ALGORITHM_LEFT_SYMMETRIC:
1329                         *pd_idx = data_disks - stripe % raid_disks;
1330                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1331                         break;
1332                 case ALGORITHM_RIGHT_SYMMETRIC:
1333                         *pd_idx = stripe % raid_disks;
1334                         *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
1335                         break;
1336                 default:
1337                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1338                                 conf->algorithm);
1339                 }
1340                 break;
1341         case 6:
1342
1343                 /**** FIX THIS ****/
1344                 switch (conf->algorithm) {
1345                 case ALGORITHM_LEFT_ASYMMETRIC:
1346                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
1347                         if (*pd_idx == raid_disks-1)
1348                                 (*dd_idx)++;    /* Q D D D P */
1349                         else if (*dd_idx >= *pd_idx)
1350                                 (*dd_idx) += 2; /* D D P Q D */
1351                         break;
1352                 case ALGORITHM_RIGHT_ASYMMETRIC:
1353                         *pd_idx = stripe % raid_disks;
1354                         if (*pd_idx == raid_disks-1)
1355                                 (*dd_idx)++;    /* Q D D D P */
1356                         else if (*dd_idx >= *pd_idx)
1357                                 (*dd_idx) += 2; /* D D P Q D */
1358                         break;
1359                 case ALGORITHM_LEFT_SYMMETRIC:
1360                         *pd_idx = raid_disks - 1 - (stripe % raid_disks);
1361                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1362                         break;
1363                 case ALGORITHM_RIGHT_SYMMETRIC:
1364                         *pd_idx = stripe % raid_disks;
1365                         *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
1366                         break;
1367                 default:
1368                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1369                                 conf->algorithm);
1370                 }
1371                 break;
1372         }
1373
1374         /*
1375          * Finally, compute the new sector number
1376          */
1377         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
1378         return new_sector;
1379 }
1380
1381
1382 static sector_t compute_blocknr(struct stripe_head *sh, int i)
1383 {
1384         raid5_conf_t *conf = sh->raid_conf;
1385         int raid_disks = sh->disks;
1386         int data_disks = raid_disks - conf->max_degraded;
1387         sector_t new_sector = sh->sector, check;
1388         int sectors_per_chunk = conf->chunk_size >> 9;
1389         sector_t stripe;
1390         int chunk_offset;
1391         int chunk_number, dummy1, dummy2, dd_idx = i;
1392         sector_t r_sector;
1393
1394
1395         chunk_offset = sector_div(new_sector, sectors_per_chunk);
1396         stripe = new_sector;
1397         BUG_ON(new_sector != stripe);
1398
1399         if (i == sh->pd_idx)
1400                 return 0;
1401         switch(conf->level) {
1402         case 4: break;
1403         case 5:
1404                 switch (conf->algorithm) {
1405                 case ALGORITHM_LEFT_ASYMMETRIC:
1406                 case ALGORITHM_RIGHT_ASYMMETRIC:
1407                         if (i > sh->pd_idx)
1408                                 i--;
1409                         break;
1410                 case ALGORITHM_LEFT_SYMMETRIC:
1411                 case ALGORITHM_RIGHT_SYMMETRIC:
1412                         if (i < sh->pd_idx)
1413                                 i += raid_disks;
1414                         i -= (sh->pd_idx + 1);
1415                         break;
1416                 default:
1417                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
1418                                conf->algorithm);
1419                 }
1420                 break;
1421         case 6:
1422                 if (i == raid6_next_disk(sh->pd_idx, raid_disks))
1423                         return 0; /* It is the Q disk */
1424                 switch (conf->algorithm) {
1425                 case ALGORITHM_LEFT_ASYMMETRIC:
1426                 case ALGORITHM_RIGHT_ASYMMETRIC:
1427                         if (sh->pd_idx == raid_disks-1)
1428                                 i--;    /* Q D D D P */
1429                         else if (i > sh->pd_idx)
1430                                 i -= 2; /* D D P Q D */
1431                         break;
1432                 case ALGORITHM_LEFT_SYMMETRIC:
1433                 case ALGORITHM_RIGHT_SYMMETRIC:
1434                         if (sh->pd_idx == raid_disks-1)
1435                                 i--; /* Q D D D P */
1436                         else {
1437                                 /* D D P Q D */
1438                                 if (i < sh->pd_idx)
1439                                         i += raid_disks;
1440                                 i -= (sh->pd_idx + 2);
1441                         }
1442                         break;
1443                 default:
1444                         printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
1445                                 conf->algorithm);
1446                 }
1447                 break;
1448         }
1449
1450         chunk_number = stripe * data_disks + i;
1451         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
1452
1453         check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
1454         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
1455                 printk(KERN_ERR "compute_blocknr: map not correct\n");
1456                 return 0;
1457         }
1458         return r_sector;
1459 }
1460
1461
1462
1463 /*
1464  * Copy data between a page in the stripe cache, and one or more bion
1465  * The page could align with the middle of the bio, or there could be
1466  * several bion, each with several bio_vecs, which cover part of the page
1467  * Multiple bion are linked together on bi_next.  There may be extras
1468  * at the end of this list.  We ignore them.
1469  */
1470 static void copy_data(int frombio, struct bio *bio,
1471                      struct page *page,
1472                      sector_t sector)
1473 {
1474         char *pa = page_address(page);
1475         struct bio_vec *bvl;
1476         int i;
1477         int page_offset;
1478
1479         if (bio->bi_sector >= sector)
1480                 page_offset = (signed)(bio->bi_sector - sector) * 512;
1481         else
1482                 page_offset = (signed)(sector - bio->bi_sector) * -512;
1483         bio_for_each_segment(bvl, bio, i) {
1484                 int len = bio_iovec_idx(bio,i)->bv_len;
1485                 int clen;
1486                 int b_offset = 0;
1487
1488                 if (page_offset < 0) {
1489                         b_offset = -page_offset;
1490                         page_offset += b_offset;
1491                         len -= b_offset;
1492                 }
1493
1494                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1495                         clen = STRIPE_SIZE - page_offset;
1496                 else clen = len;
1497
1498                 if (clen > 0) {
1499                         char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
1500                         if (frombio)
1501                                 memcpy(pa+page_offset, ba+b_offset, clen);
1502                         else
1503                                 memcpy(ba+b_offset, pa+page_offset, clen);
1504                         __bio_kunmap_atomic(ba, KM_USER0);
1505                 }
1506                 if (clen < len) /* hit end of page */
1507                         break;
1508                 page_offset +=  len;
1509         }
1510 }
1511
1512 #define check_xor()     do {                                              \
1513                                 if (count == MAX_XOR_BLOCKS) {            \
1514                                 xor_blocks(count, STRIPE_SIZE, dest, ptr);\
1515                                 count = 0;                                \
1516                            }                                              \
1517                         } while(0)
1518
1519
1520 static void compute_block(struct stripe_head *sh, int dd_idx)
1521 {
1522         int i, count, disks = sh->disks;
1523         void *ptr[MAX_XOR_BLOCKS], *dest, *p;
1524
1525         pr_debug("compute_block, stripe %llu, idx %d\n",
1526                 (unsigned long long)sh->sector, dd_idx);
1527
1528         dest = page_address(sh->dev[dd_idx].page);
1529         memset(dest, 0, STRIPE_SIZE);
1530         count = 0;
1531         for (i = disks ; i--; ) {
1532                 if (i == dd_idx)
1533                         continue;
1534                 p = page_address(sh->dev[i].page);
1535                 if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
1536                         ptr[count++] = p;
1537                 else
1538                         printk(KERN_ERR "compute_block() %d, stripe %llu, %d"
1539                                 " not present\n", dd_idx,
1540                                 (unsigned long long)sh->sector, i);
1541
1542                 check_xor();
1543         }
1544         if (count)
1545                 xor_blocks(count, STRIPE_SIZE, dest, ptr);
1546         set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1547 }
1548
1549 static void compute_parity5(struct stripe_head *sh, int method)
1550 {
1551         raid5_conf_t *conf = sh->raid_conf;
1552         int i, pd_idx = sh->pd_idx, disks = sh->disks, count;
1553         void *ptr[MAX_XOR_BLOCKS], *dest;
1554         struct bio *chosen;
1555
1556         pr_debug("compute_parity5, stripe %llu, method %d\n",
1557                 (unsigned long long)sh->sector, method);
1558
1559         count = 0;
1560         dest = page_address(sh->dev[pd_idx].page);
1561         switch(method) {
1562         case READ_MODIFY_WRITE:
1563                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags));
1564                 for (i=disks ; i-- ;) {
1565                         if (i==pd_idx)
1566                                 continue;
1567                         if (sh->dev[i].towrite &&
1568                             test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
1569                                 ptr[count++] = page_address(sh->dev[i].page);
1570                                 chosen = sh->dev[i].towrite;
1571                                 sh->dev[i].towrite = NULL;
1572
1573                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1574                                         wake_up(&conf->wait_for_overlap);
1575
1576                                 BUG_ON(sh->dev[i].written);
1577                                 sh->dev[i].written = chosen;
1578                                 check_xor();
1579                         }
1580                 }
1581                 break;
1582         case RECONSTRUCT_WRITE:
1583                 memset(dest, 0, STRIPE_SIZE);
1584                 for (i= disks; i-- ;)
1585                         if (i!=pd_idx && sh->dev[i].towrite) {
1586                                 chosen = sh->dev[i].towrite;
1587                                 sh->dev[i].towrite = NULL;
1588
1589                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1590                                         wake_up(&conf->wait_for_overlap);
1591
1592                                 BUG_ON(sh->dev[i].written);
1593                                 sh->dev[i].written = chosen;
1594                         }
1595                 break;
1596         case CHECK_PARITY:
1597                 break;
1598         }
1599         if (count) {
1600                 xor_blocks(count, STRIPE_SIZE, dest, ptr);
1601                 count = 0;
1602         }
1603
1604         for (i = disks; i--;)
1605                 if (sh->dev[i].written) {
1606                         sector_t sector = sh->dev[i].sector;
1607                         struct bio *wbi = sh->dev[i].written;
1608                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1609                                 copy_data(1, wbi, sh->dev[i].page, sector);
1610                                 wbi = r5_next_bio(wbi, sector);
1611                         }
1612
1613                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1614                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1615                 }
1616
1617         switch(method) {
1618         case RECONSTRUCT_WRITE:
1619         case CHECK_PARITY:
1620                 for (i=disks; i--;)
1621                         if (i != pd_idx) {
1622                                 ptr[count++] = page_address(sh->dev[i].page);
1623                                 check_xor();
1624                         }
1625                 break;
1626         case READ_MODIFY_WRITE:
1627                 for (i = disks; i--;)
1628                         if (sh->dev[i].written) {
1629                                 ptr[count++] = page_address(sh->dev[i].page);
1630                                 check_xor();
1631                         }
1632         }
1633         if (count)
1634                 xor_blocks(count, STRIPE_SIZE, dest, ptr);
1635
1636         if (method != CHECK_PARITY) {
1637                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1638                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1639         } else
1640                 clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1641 }
1642
1643 static void compute_parity6(struct stripe_head *sh, int method)
1644 {
1645         raid6_conf_t *conf = sh->raid_conf;
1646         int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
1647         struct bio *chosen;
1648         /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1649         void *ptrs[disks];
1650
1651         qd_idx = raid6_next_disk(pd_idx, disks);
1652         d0_idx = raid6_next_disk(qd_idx, disks);
1653
1654         pr_debug("compute_parity, stripe %llu, method %d\n",
1655                 (unsigned long long)sh->sector, method);
1656
1657         switch(method) {
1658         case READ_MODIFY_WRITE:
1659                 BUG();          /* READ_MODIFY_WRITE N/A for RAID-6 */
1660         case RECONSTRUCT_WRITE:
1661                 for (i= disks; i-- ;)
1662                         if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
1663                                 chosen = sh->dev[i].towrite;
1664                                 sh->dev[i].towrite = NULL;
1665
1666                                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
1667                                         wake_up(&conf->wait_for_overlap);
1668
1669                                 BUG_ON(sh->dev[i].written);
1670                                 sh->dev[i].written = chosen;
1671                         }
1672                 break;
1673         case CHECK_PARITY:
1674                 BUG();          /* Not implemented yet */
1675         }
1676
1677         for (i = disks; i--;)
1678                 if (sh->dev[i].written) {
1679                         sector_t sector = sh->dev[i].sector;
1680                         struct bio *wbi = sh->dev[i].written;
1681                         while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) {
1682                                 copy_data(1, wbi, sh->dev[i].page, sector);
1683                                 wbi = r5_next_bio(wbi, sector);
1684                         }
1685
1686                         set_bit(R5_LOCKED, &sh->dev[i].flags);
1687                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
1688                 }
1689
1690 //      switch(method) {
1691 //      case RECONSTRUCT_WRITE:
1692 //      case CHECK_PARITY:
1693 //      case UPDATE_PARITY:
1694                 /* Note that unlike RAID-5, the ordering of the disks matters greatly. */
1695                 /* FIX: Is this ordering of drives even remotely optimal? */
1696                 count = 0;
1697                 i = d0_idx;
1698                 do {
1699                         ptrs[count++] = page_address(sh->dev[i].page);
1700                         if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1701                                 printk("block %d/%d not uptodate on parity calc\n", i,count);
1702                         i = raid6_next_disk(i, disks);
1703                 } while ( i != d0_idx );
1704 //              break;
1705 //      }
1706
1707         raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
1708
1709         switch(method) {
1710         case RECONSTRUCT_WRITE:
1711                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1712                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1713                 set_bit(R5_LOCKED,   &sh->dev[pd_idx].flags);
1714                 set_bit(R5_LOCKED,   &sh->dev[qd_idx].flags);
1715                 break;
1716         case UPDATE_PARITY:
1717                 set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1718                 set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
1719                 break;
1720         }
1721 }
1722
1723
1724 /* Compute one missing block */
1725 static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
1726 {
1727         int i, count, disks = sh->disks;
1728         void *ptr[MAX_XOR_BLOCKS], *dest, *p;
1729         int pd_idx = sh->pd_idx;
1730         int qd_idx = raid6_next_disk(pd_idx, disks);
1731
1732         pr_debug("compute_block_1, stripe %llu, idx %d\n",
1733                 (unsigned long long)sh->sector, dd_idx);
1734
1735         if ( dd_idx == qd_idx ) {
1736                 /* We're actually computing the Q drive */
1737                 compute_parity6(sh, UPDATE_PARITY);
1738         } else {
1739                 dest = page_address(sh->dev[dd_idx].page);
1740                 if (!nozero) memset(dest, 0, STRIPE_SIZE);
1741                 count = 0;
1742                 for (i = disks ; i--; ) {
1743                         if (i == dd_idx || i == qd_idx)
1744                                 continue;
1745                         p = page_address(sh->dev[i].page);
1746                         if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
1747                                 ptr[count++] = p;
1748                         else
1749                                 printk("compute_block() %d, stripe %llu, %d"
1750                                        " not present\n", dd_idx,
1751                                        (unsigned long long)sh->sector, i);
1752
1753                         check_xor();
1754                 }
1755                 if (count)
1756                         xor_blocks(count, STRIPE_SIZE, dest, ptr);
1757                 if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1758                 else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags);
1759         }
1760 }
1761
1762 /* Compute two missing blocks */
1763 static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
1764 {
1765         int i, count, disks = sh->disks;
1766         int pd_idx = sh->pd_idx;
1767         int qd_idx = raid6_next_disk(pd_idx, disks);
1768         int d0_idx = raid6_next_disk(qd_idx, disks);
1769         int faila, failb;
1770
1771         /* faila and failb are disk numbers relative to d0_idx */
1772         /* pd_idx become disks-2 and qd_idx become disks-1 */
1773         faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
1774         failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
1775
1776         BUG_ON(faila == failb);
1777         if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
1778
1779         pr_debug("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
1780                (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
1781
1782         if ( failb == disks-1 ) {
1783                 /* Q disk is one of the missing disks */
1784                 if ( faila == disks-2 ) {
1785                         /* Missing P+Q, just recompute */
1786                         compute_parity6(sh, UPDATE_PARITY);
1787                         return;
1788                 } else {
1789                         /* We're missing D+Q; recompute D from P */
1790                         compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
1791                         compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
1792                         return;
1793                 }
1794         }
1795
1796         /* We're missing D+P or D+D; build pointer table */
1797         {
1798                 /**** FIX THIS: This could be very bad if disks is close to 256 ****/
1799                 void *ptrs[disks];
1800
1801                 count = 0;
1802                 i = d0_idx;
1803                 do {
1804                         ptrs[count++] = page_address(sh->dev[i].page);
1805                         i = raid6_next_disk(i, disks);
1806                         if (i != dd_idx1 && i != dd_idx2 &&
1807                             !test_bit(R5_UPTODATE, &sh->dev[i].flags))
1808                                 printk("compute_2 with missing block %d/%d\n", count, i);
1809                 } while ( i != d0_idx );
1810
1811                 if ( failb == disks-2 ) {
1812                         /* We're missing D+P. */
1813                         raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
1814                 } else {
1815                         /* We're missing D+D. */
1816                         raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
1817                 }
1818
1819                 /* Both the above update both missing blocks */
1820                 set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
1821                 set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
1822         }
1823 }
1824
1825 static int
1826 handle_write_operations5(struct stripe_head *sh, int rcw, int expand)
1827 {
1828         int i, pd_idx = sh->pd_idx, disks = sh->disks;
1829         int locked = 0;
1830
1831         if (rcw) {
1832                 /* if we are not expanding this is a proper write request, and
1833                  * there will be bios with new data to be drained into the
1834                  * stripe cache
1835                  */
1836                 if (!expand) {
1837                         set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
1838                         sh->ops.count++;
1839                 }
1840
1841                 set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
1842                 sh->ops.count++;
1843
1844                 for (i = disks; i--; ) {
1845                         struct r5dev *dev = &sh->dev[i];
1846
1847                         if (dev->towrite) {
1848                                 set_bit(R5_LOCKED, &dev->flags);
1849                                 if (!expand)
1850                                         clear_bit(R5_UPTODATE, &dev->flags);
1851                                 locked++;
1852                         }
1853                 }
1854         } else {
1855                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
1856                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
1857
1858                 set_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
1859                 set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
1860                 set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
1861
1862                 sh->ops.count += 3;
1863
1864                 for (i = disks; i--; ) {
1865                         struct r5dev *dev = &sh->dev[i];
1866                         if (i == pd_idx)
1867                                 continue;
1868
1869                         /* For a read-modify write there may be blocks that are
1870                          * locked for reading while others are ready to be
1871                          * written so we distinguish these blocks by the
1872                          * R5_Wantprexor bit
1873                          */
1874                         if (dev->towrite &&
1875                             (test_bit(R5_UPTODATE, &dev->flags) ||
1876                             test_bit(R5_Wantcompute, &dev->flags))) {
1877                                 set_bit(R5_Wantprexor, &dev->flags);
1878                                 set_bit(R5_LOCKED, &dev->flags);
1879                                 clear_bit(R5_UPTODATE, &dev->flags);
1880                                 locked++;
1881                         }
1882                 }
1883         }
1884
1885         /* keep the parity disk locked while asynchronous operations
1886          * are in flight
1887          */
1888         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
1889         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
1890         locked++;
1891
1892         pr_debug("%s: stripe %llu locked: %d pending: %lx\n",
1893                 __FUNCTION__, (unsigned long long)sh->sector,
1894                 locked, sh->ops.pending);
1895
1896         return locked;
1897 }
1898
1899 /*
1900  * Each stripe/dev can have one or more bion attached.
1901  * toread/towrite point to the first in a chain.
1902  * The bi_next chain must be in order.
1903  */
1904 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
1905 {
1906         struct bio **bip;
1907         raid5_conf_t *conf = sh->raid_conf;
1908         int firstwrite=0;
1909
1910         pr_debug("adding bh b#%llu to stripe s#%llu\n",
1911                 (unsigned long long)bi->bi_sector,
1912                 (unsigned long long)sh->sector);
1913
1914
1915         spin_lock(&sh->lock);
1916         spin_lock_irq(&conf->device_lock);
1917         if (forwrite) {
1918                 bip = &sh->dev[dd_idx].towrite;
1919                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
1920                         firstwrite = 1;
1921         } else
1922                 bip = &sh->dev[dd_idx].toread;
1923         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
1924                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
1925                         goto overlap;
1926                 bip = & (*bip)->bi_next;
1927         }
1928         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
1929                 goto overlap;
1930
1931         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
1932         if (*bip)
1933                 bi->bi_next = *bip;
1934         *bip = bi;
1935         bi->bi_phys_segments ++;
1936         spin_unlock_irq(&conf->device_lock);
1937         spin_unlock(&sh->lock);
1938
1939         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
1940                 (unsigned long long)bi->bi_sector,
1941                 (unsigned long long)sh->sector, dd_idx);
1942
1943         if (conf->mddev->bitmap && firstwrite) {
1944                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
1945                                   STRIPE_SECTORS, 0);
1946                 sh->bm_seq = conf->seq_flush+1;
1947                 set_bit(STRIPE_BIT_DELAY, &sh->state);
1948         }
1949
1950         if (forwrite) {
1951                 /* check if page is covered */
1952                 sector_t sector = sh->dev[dd_idx].sector;
1953                 for (bi=sh->dev[dd_idx].towrite;
1954                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
1955                              bi && bi->bi_sector <= sector;
1956                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
1957                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
1958                                 sector = bi->bi_sector + (bi->bi_size>>9);
1959                 }
1960                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
1961                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
1962         }
1963         return 1;
1964
1965  overlap:
1966         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
1967         spin_unlock_irq(&conf->device_lock);
1968         spin_unlock(&sh->lock);
1969         return 0;
1970 }
1971
1972 static void end_reshape(raid5_conf_t *conf);
1973
1974 static int page_is_zero(struct page *p)
1975 {
1976         char *a = page_address(p);
1977         return ((*(u32*)a) == 0 &&
1978                 memcmp(a, a+4, STRIPE_SIZE-4)==0);
1979 }
1980
1981 static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
1982 {
1983         int sectors_per_chunk = conf->chunk_size >> 9;
1984         int pd_idx, dd_idx;
1985         int chunk_offset = sector_div(stripe, sectors_per_chunk);
1986
1987         raid5_compute_sector(stripe * (disks - conf->max_degraded)
1988                              *sectors_per_chunk + chunk_offset,
1989                              disks, disks - conf->max_degraded,
1990                              &dd_idx, &pd_idx, conf);
1991         return pd_idx;
1992 }
1993
1994 static void
1995 handle_requests_to_failed_array(raid5_conf_t *conf, struct stripe_head *sh,
1996                                 struct stripe_head_state *s, int disks,
1997                                 struct bio **return_bi)
1998 {
1999         int i;
2000         for (i = disks; i--; ) {
2001                 struct bio *bi;
2002                 int bitmap_end = 0;
2003
2004                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2005                         mdk_rdev_t *rdev;
2006                         rcu_read_lock();
2007                         rdev = rcu_dereference(conf->disks[i].rdev);
2008                         if (rdev && test_bit(In_sync, &rdev->flags))
2009                                 /* multiple read failures in one stripe */
2010                                 md_error(conf->mddev, rdev);
2011                         rcu_read_unlock();
2012                 }
2013                 spin_lock_irq(&conf->device_lock);
2014                 /* fail all writes first */
2015                 bi = sh->dev[i].towrite;
2016                 sh->dev[i].towrite = NULL;
2017                 if (bi) {
2018                         s->to_write--;
2019                         bitmap_end = 1;
2020                 }
2021
2022                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2023                         wake_up(&conf->wait_for_overlap);
2024
2025                 while (bi && bi->bi_sector <
2026                         sh->dev[i].sector + STRIPE_SECTORS) {
2027                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2028                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2029                         if (--bi->bi_phys_segments == 0) {
2030                                 md_write_end(conf->mddev);
2031                                 bi->bi_next = *return_bi;
2032                                 *return_bi = bi;
2033                         }
2034                         bi = nextbi;
2035                 }
2036                 /* and fail all 'written' */
2037                 bi = sh->dev[i].written;
2038                 sh->dev[i].written = NULL;
2039                 if (bi) bitmap_end = 1;
2040                 while (bi && bi->bi_sector <
2041                        sh->dev[i].sector + STRIPE_SECTORS) {
2042                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2043                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2044                         if (--bi->bi_phys_segments == 0) {
2045                                 md_write_end(conf->mddev);
2046                                 bi->bi_next = *return_bi;
2047                                 *return_bi = bi;
2048                         }
2049                         bi = bi2;
2050                 }
2051
2052                 /* fail any reads if this device is non-operational and
2053                  * the data has not reached the cache yet.
2054                  */
2055                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2056                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2057                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
2058                         bi = sh->dev[i].toread;
2059                         sh->dev[i].toread = NULL;
2060                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2061                                 wake_up(&conf->wait_for_overlap);
2062                         if (bi) s->to_read--;
2063                         while (bi && bi->bi_sector <
2064                                sh->dev[i].sector + STRIPE_SECTORS) {
2065                                 struct bio *nextbi =
2066                                         r5_next_bio(bi, sh->dev[i].sector);
2067                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2068                                 if (--bi->bi_phys_segments == 0) {
2069                                         bi->bi_next = *return_bi;
2070                                         *return_bi = bi;
2071                                 }
2072                                 bi = nextbi;
2073                         }
2074                 }
2075                 spin_unlock_irq(&conf->device_lock);
2076                 if (bitmap_end)
2077                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2078                                         STRIPE_SECTORS, 0, 0);
2079         }
2080
2081 }
2082
2083 /* __handle_issuing_new_read_requests5 - returns 0 if there are no more disks
2084  * to process
2085  */
2086 static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
2087                         struct stripe_head_state *s, int disk_idx, int disks)
2088 {
2089         struct r5dev *dev = &sh->dev[disk_idx];
2090         struct r5dev *failed_dev = &sh->dev[s->failed_num];
2091
2092         /* don't schedule compute operations or reads on the parity block while
2093          * a check is in flight
2094          */
2095         if ((disk_idx == sh->pd_idx) &&
2096              test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
2097                 return ~0;
2098
2099         /* is the data in this block needed, and can we get it? */
2100         if (!test_bit(R5_LOCKED, &dev->flags) &&
2101             !test_bit(R5_UPTODATE, &dev->flags) && (dev->toread ||
2102             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2103              s->syncing || s->expanding || (s->failed &&
2104              (failed_dev->toread || (failed_dev->towrite &&
2105              !test_bit(R5_OVERWRITE, &failed_dev->flags)
2106              ))))) {
2107                 /* 1/ We would like to get this block, possibly by computing it,
2108                  * but we might not be able to.
2109                  *
2110                  * 2/ Since parity check operations potentially make the parity
2111                  * block !uptodate it will need to be refreshed before any
2112                  * compute operations on data disks are scheduled.
2113                  *
2114                  * 3/ We hold off parity block re-reads until check operations
2115                  * have quiesced.
2116                  */
2117                 if ((s->uptodate == disks - 1) &&
2118                     !test_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
2119                         set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
2120                         set_bit(R5_Wantcompute, &dev->flags);
2121                         sh->ops.target = disk_idx;
2122                         s->req_compute = 1;
2123                         sh->ops.count++;
2124                         /* Careful: from this point on 'uptodate' is in the eye
2125                          * of raid5_run_ops which services 'compute' operations
2126                          * before writes. R5_Wantcompute flags a block that will
2127                          * be R5_UPTODATE by the time it is needed for a
2128                          * subsequent operation.
2129                          */
2130                         s->uptodate++;
2131                         return 0; /* uptodate + compute == disks */
2132                 } else if ((s->uptodate < disks - 1) &&
2133                         test_bit(R5_Insync, &dev->flags)) {
2134                         /* Note: we hold off compute operations while checks are
2135                          * in flight, but we still prefer 'compute' over 'read'
2136                          * hence we only read if (uptodate < * disks-1)
2137                          */
2138                         set_bit(R5_LOCKED, &dev->flags);
2139                         set_bit(R5_Wantread, &dev->flags);
2140                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2141                                 sh->ops.count++;
2142                         s->locked++;
2143                         pr_debug("Reading block %d (sync=%d)\n", disk_idx,
2144                                 s->syncing);
2145                 }
2146         }
2147
2148         return ~0;
2149 }
2150
2151 static void handle_issuing_new_read_requests5(struct stripe_head *sh,
2152                         struct stripe_head_state *s, int disks)
2153 {
2154         int i;
2155
2156         /* Clear completed compute operations.  Parity recovery
2157          * (STRIPE_OP_MOD_REPAIR_PD) implies a write-back which is handled
2158          * later on in this routine
2159          */
2160         if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
2161                 !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2162                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
2163                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
2164                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
2165         }
2166
2167         /* look for blocks to read/compute, skip this if a compute
2168          * is already in flight, or if the stripe contents are in the
2169          * midst of changing due to a write
2170          */
2171         if (!test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
2172                 !test_bit(STRIPE_OP_PREXOR, &sh->ops.pending) &&
2173                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2174                 for (i = disks; i--; )
2175                         if (__handle_issuing_new_read_requests5(
2176                                 sh, s, i, disks) == 0)
2177                                 break;
2178         }
2179         set_bit(STRIPE_HANDLE, &sh->state);
2180 }
2181
2182 static void handle_issuing_new_read_requests6(struct stripe_head *sh,
2183                         struct stripe_head_state *s, struct r6_state *r6s,
2184                         int disks)
2185 {
2186         int i;
2187         for (i = disks; i--; ) {
2188                 struct r5dev *dev = &sh->dev[i];
2189                 if (!test_bit(R5_LOCKED, &dev->flags) &&
2190                     !test_bit(R5_UPTODATE, &dev->flags) &&
2191                     (dev->toread || (dev->towrite &&
2192                      !test_bit(R5_OVERWRITE, &dev->flags)) ||
2193                      s->syncing || s->expanding ||
2194                      (s->failed >= 1 &&
2195                       (sh->dev[r6s->failed_num[0]].toread ||
2196                        s->to_write)) ||
2197                      (s->failed >= 2 &&
2198                       (sh->dev[r6s->failed_num[1]].toread ||
2199                        s->to_write)))) {
2200                         /* we would like to get this block, possibly
2201                          * by computing it, but we might not be able to
2202                          */
2203                         if (s->uptodate == disks-1) {
2204                                 pr_debug("Computing stripe %llu block %d\n",
2205                                        (unsigned long long)sh->sector, i);
2206                                 compute_block_1(sh, i, 0);
2207                                 s->uptodate++;
2208                         } else if ( s->uptodate == disks-2 && s->failed >= 2 ) {
2209                                 /* Computing 2-failure is *very* expensive; only
2210                                  * do it if failed >= 2
2211                                  */
2212                                 int other;
2213                                 for (other = disks; other--; ) {
2214                                         if (other == i)
2215                                                 continue;
2216                                         if (!test_bit(R5_UPTODATE,
2217                                               &sh->dev[other].flags))
2218                                                 break;
2219                                 }
2220                                 BUG_ON(other < 0);
2221                                 pr_debug("Computing stripe %llu blocks %d,%d\n",
2222                                        (unsigned long long)sh->sector,
2223                                        i, other);
2224                                 compute_block_2(sh, i, other);
2225                                 s->uptodate += 2;
2226                         } else if (test_bit(R5_Insync, &dev->flags)) {
2227                                 set_bit(R5_LOCKED, &dev->flags);
2228                                 set_bit(R5_Wantread, &dev->flags);
2229                                 s->locked++;
2230                                 pr_debug("Reading block %d (sync=%d)\n",
2231                                         i, s->syncing);
2232                         }
2233                 }
2234         }
2235         set_bit(STRIPE_HANDLE, &sh->state);
2236 }
2237
2238
2239 /* handle_completed_write_requests
2240  * any written block on an uptodate or failed drive can be returned.
2241  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2242  * never LOCKED, so we don't need to test 'failed' directly.
2243  */
2244 static void handle_completed_write_requests(raid5_conf_t *conf,
2245         struct stripe_head *sh, int disks, struct bio **return_bi)
2246 {
2247         int i;
2248         struct r5dev *dev;
2249
2250         for (i = disks; i--; )
2251                 if (sh->dev[i].written) {
2252                         dev = &sh->dev[i];
2253                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2254                                 test_bit(R5_UPTODATE, &dev->flags)) {
2255                                 /* We can return any write requests */
2256                                 struct bio *wbi, *wbi2;
2257                                 int bitmap_end = 0;
2258                                 pr_debug("Return write for disc %d\n", i);
2259                                 spin_lock_irq(&conf->device_lock);
2260                                 wbi = dev->written;
2261                                 dev->written = NULL;
2262                                 while (wbi && wbi->bi_sector <
2263                                         dev->sector + STRIPE_SECTORS) {
2264                                         wbi2 = r5_next_bio(wbi, dev->sector);
2265                                         if (--wbi->bi_phys_segments == 0) {
2266                                                 md_write_end(conf->mddev);
2267                                                 wbi->bi_next = *return_bi;
2268                                                 *return_bi = wbi;
2269                                         }
2270                                         wbi = wbi2;
2271                                 }
2272                                 if (dev->towrite == NULL)
2273                                         bitmap_end = 1;
2274                                 spin_unlock_irq(&conf->device_lock);
2275                                 if (bitmap_end)
2276                                         bitmap_endwrite(conf->mddev->bitmap,
2277                                                         sh->sector,
2278                                                         STRIPE_SECTORS,
2279                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2280                                                         0);
2281                         }
2282                 }
2283 }
2284
2285 static void handle_issuing_new_write_requests5(raid5_conf_t *conf,
2286                 struct stripe_head *sh, struct stripe_head_state *s, int disks)
2287 {
2288         int rmw = 0, rcw = 0, i;
2289         for (i = disks; i--; ) {
2290                 /* would I have to read this buffer for read_modify_write */
2291                 struct r5dev *dev = &sh->dev[i];
2292                 if ((dev->towrite || i == sh->pd_idx) &&
2293                     !test_bit(R5_LOCKED, &dev->flags) &&
2294                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2295                       test_bit(R5_Wantcompute, &dev->flags))) {
2296                         if (test_bit(R5_Insync, &dev->flags))
2297                                 rmw++;
2298                         else
2299                                 rmw += 2*disks;  /* cannot read it */
2300                 }
2301                 /* Would I have to read this buffer for reconstruct_write */
2302                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2303                     !test_bit(R5_LOCKED, &dev->flags) &&
2304                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2305                     test_bit(R5_Wantcompute, &dev->flags))) {
2306                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2307                         else
2308                                 rcw += 2*disks;
2309                 }
2310         }
2311         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2312                 (unsigned long long)sh->sector, rmw, rcw);
2313         set_bit(STRIPE_HANDLE, &sh->state);
2314         if (rmw < rcw && rmw > 0)
2315                 /* prefer read-modify-write, but need to get some data */
2316                 for (i = disks; i--; ) {
2317                         struct r5dev *dev = &sh->dev[i];
2318                         if ((dev->towrite || i == sh->pd_idx) &&
2319                             !test_bit(R5_LOCKED, &dev->flags) &&
2320                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2321                             test_bit(R5_Wantcompute, &dev->flags)) &&
2322                             test_bit(R5_Insync, &dev->flags)) {
2323                                 if (
2324                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2325                                         pr_debug("Read_old block "
2326                                                 "%d for r-m-w\n", i);
2327                                         set_bit(R5_LOCKED, &dev->flags);
2328                                         set_bit(R5_Wantread, &dev->flags);
2329                                         s->locked++;
2330                                 } else {
2331                                         set_bit(STRIPE_DELAYED, &sh->state);
2332                                         set_bit(STRIPE_HANDLE, &sh->state);
2333                                 }
2334                         }
2335                 }
2336         if (rcw <= rmw && rcw > 0)
2337                 /* want reconstruct write, but need to get some data */
2338                 for (i = disks; i--; ) {
2339                         struct r5dev *dev = &sh->dev[i];
2340                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2341                             i != sh->pd_idx &&
2342                             !test_bit(R5_LOCKED, &dev->flags) &&
2343                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2344                             test_bit(R5_Wantcompute, &dev->flags)) &&
2345                             test_bit(R5_Insync, &dev->flags)) {
2346                                 if (
2347                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2348                                         pr_debug("Read_old block "
2349                                                 "%d for Reconstruct\n", i);
2350                                         set_bit(R5_LOCKED, &dev->flags);
2351                                         set_bit(R5_Wantread, &dev->flags);
2352                                         s->locked++;
2353                                 } else {
2354                                         set_bit(STRIPE_DELAYED, &sh->state);
2355                                         set_bit(STRIPE_HANDLE, &sh->state);
2356                                 }
2357                         }
2358                 }
2359         /* now if nothing is locked, and if we have enough data,
2360          * we can start a write request
2361          */
2362         /* since handle_stripe can be called at any time we need to handle the
2363          * case where a compute block operation has been submitted and then a
2364          * subsequent call wants to start a write request.  raid5_run_ops only
2365          * handles the case where compute block and postxor are requested
2366          * simultaneously.  If this is not the case then new writes need to be
2367          * held off until the compute completes.
2368          */
2369         if ((s->req_compute ||
2370             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) &&
2371                 (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2372                 !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2373                 s->locked += handle_write_operations5(sh, rcw == 0, 0);
2374 }
2375
2376 static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
2377                 struct stripe_head *sh, struct stripe_head_state *s,
2378                 struct r6_state *r6s, int disks)
2379 {
2380         int rcw = 0, must_compute = 0, pd_idx = sh->pd_idx, i;
2381         int qd_idx = r6s->qd_idx;
2382         for (i = disks; i--; ) {
2383                 struct r5dev *dev = &sh->dev[i];
2384                 /* Would I have to read this buffer for reconstruct_write */
2385                 if (!test_bit(R5_OVERWRITE, &dev->flags)
2386                     && i != pd_idx && i != qd_idx
2387                     && (!test_bit(R5_LOCKED, &dev->flags)
2388                             ) &&
2389                     !test_bit(R5_UPTODATE, &dev->flags)) {
2390                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2391                         else {
2392                                 pr_debug("raid6: must_compute: "
2393                                         "disk %d flags=%#lx\n", i, dev->flags);
2394                                 must_compute++;
2395                         }
2396                 }
2397         }
2398         pr_debug("for sector %llu, rcw=%d, must_compute=%d\n",
2399                (unsigned long long)sh->sector, rcw, must_compute);
2400         set_bit(STRIPE_HANDLE, &sh->state);
2401
2402         if (rcw > 0)
2403                 /* want reconstruct write, but need to get some data */
2404                 for (i = disks; i--; ) {
2405                         struct r5dev *dev = &sh->dev[i];
2406                         if (!test_bit(R5_OVERWRITE, &dev->flags)
2407                             && !(s->failed == 0 && (i == pd_idx || i == qd_idx))
2408                             && !test_bit(R5_LOCKED, &dev->flags) &&
2409                             !test_bit(R5_UPTODATE, &dev->flags) &&
2410                             test_bit(R5_Insync, &dev->flags)) {
2411                                 if (
2412                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2413                                         pr_debug("Read_old stripe %llu "
2414                                                 "block %d for Reconstruct\n",
2415                                              (unsigned long long)sh->sector, i);
2416                                         set_bit(R5_LOCKED, &dev->flags);
2417                                         set_bit(R5_Wantread, &dev->flags);
2418                                         s->locked++;
2419                                 } else {
2420                                         pr_debug("Request delayed stripe %llu "
2421                                                 "block %d for Reconstruct\n",
2422                                              (unsigned long long)sh->sector, i);
2423                                         set_bit(STRIPE_DELAYED, &sh->state);
2424                                         set_bit(STRIPE_HANDLE, &sh->state);
2425                                 }
2426                         }
2427                 }
2428         /* now if nothing is locked, and if we have enough data, we can start a
2429          * write request
2430          */
2431         if (s->locked == 0 && rcw == 0 &&
2432             !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
2433                 if (must_compute > 0) {
2434                         /* We have failed blocks and need to compute them */
2435                         switch (s->failed) {
2436                         case 0:
2437                                 BUG();
2438                         case 1:
2439                                 compute_block_1(sh, r6s->failed_num[0], 0);
2440                                 break;
2441                         case 2:
2442                                 compute_block_2(sh, r6s->failed_num[0],
2443                                                 r6s->failed_num[1]);
2444                                 break;
2445                         default: /* This request should have been failed? */
2446                                 BUG();
2447                         }
2448                 }
2449
2450                 pr_debug("Computing parity for stripe %llu\n",
2451                         (unsigned long long)sh->sector);
2452                 compute_parity6(sh, RECONSTRUCT_WRITE);
2453                 /* now every locked buffer is ready to be written */
2454                 for (i = disks; i--; )
2455                         if (test_bit(R5_LOCKED, &sh->dev[i].flags)) {
2456                                 pr_debug("Writing stripe %llu block %d\n",
2457                                        (unsigned long long)sh->sector, i);
2458                                 s->locked++;
2459                                 set_bit(R5_Wantwrite, &sh->dev[i].flags);
2460                         }
2461                 /* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */
2462                 set_bit(STRIPE_INSYNC, &sh->state);
2463
2464                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2465                         atomic_dec(&conf->preread_active_stripes);
2466                         if (atomic_read(&conf->preread_active_stripes) <
2467                             IO_THRESHOLD)
2468                                 md_wakeup_thread(conf->mddev->thread);
2469                 }
2470         }
2471 }
2472
2473 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
2474                                 struct stripe_head_state *s, int disks)
2475 {
2476         set_bit(STRIPE_HANDLE, &sh->state);
2477         /* Take one of the following actions:
2478          * 1/ start a check parity operation if (uptodate == disks)
2479          * 2/ finish a check parity operation and act on the result
2480          * 3/ skip to the writeback section if we previously
2481          *    initiated a recovery operation
2482          */
2483         if (s->failed == 0 &&
2484             !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2485                 if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
2486                         BUG_ON(s->uptodate != disks);
2487                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2488                         sh->ops.count++;
2489                         s->uptodate--;
2490                 } else if (
2491                        test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) {
2492                         clear_bit(STRIPE_OP_CHECK, &sh->ops.ack);
2493                         clear_bit(STRIPE_OP_CHECK, &sh->ops.pending);
2494
2495                         if (sh->ops.zero_sum_result == 0)
2496                                 /* parity is correct (on disc,
2497                                  * not in buffer any more)
2498                                  */
2499                                 set_bit(STRIPE_INSYNC, &sh->state);
2500                         else {
2501                                 conf->mddev->resync_mismatches +=
2502                                         STRIPE_SECTORS;
2503                                 if (test_bit(
2504                                      MD_RECOVERY_CHECK, &conf->mddev->recovery))
2505                                         /* don't try to repair!! */
2506                                         set_bit(STRIPE_INSYNC, &sh->state);
2507                                 else {
2508                                         set_bit(STRIPE_OP_COMPUTE_BLK,
2509                                                 &sh->ops.pending);
2510                                         set_bit(STRIPE_OP_MOD_REPAIR_PD,
2511                                                 &sh->ops.pending);
2512                                         set_bit(R5_Wantcompute,
2513                                                 &sh->dev[sh->pd_idx].flags);
2514                                         sh->ops.target = sh->pd_idx;
2515                                         sh->ops.count++;
2516                                         s->uptodate++;
2517                                 }
2518                         }
2519                 }
2520         }
2521
2522         /* check if we can clear a parity disk reconstruct */
2523         if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
2524                 test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
2525
2526                 clear_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending);
2527                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
2528                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
2529                 clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
2530         }
2531
2532         /* Wait for check parity and compute block operations to complete
2533          * before write-back
2534          */
2535         if (!test_bit(STRIPE_INSYNC, &sh->state) &&
2536                 !test_bit(STRIPE_OP_CHECK, &sh->ops.pending) &&
2537                 !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) {
2538                 struct r5dev *dev;
2539                 /* either failed parity check, or recovery is happening */
2540                 if (s->failed == 0)
2541                         s->failed_num = sh->pd_idx;
2542                 dev = &sh->dev[s->failed_num];
2543                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2544                 BUG_ON(s->uptodate != disks);
2545
2546                 set_bit(R5_LOCKED, &dev->flags);
2547                 set_bit(R5_Wantwrite, &dev->flags);
2548                 clear_bit(STRIPE_DEGRADED, &sh->state);
2549                 s->locked++;
2550                 set_bit(STRIPE_INSYNC, &sh->state);
2551         }
2552 }
2553
2554
2555 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
2556                                 struct stripe_head_state *s,
2557                                 struct r6_state *r6s, struct page *tmp_page,
2558                                 int disks)
2559 {
2560         int update_p = 0, update_q = 0;
2561         struct r5dev *dev;
2562         int pd_idx = sh->pd_idx;
2563         int qd_idx = r6s->qd_idx;
2564
2565         set_bit(STRIPE_HANDLE, &sh->state);
2566
2567         BUG_ON(s->failed > 2);
2568         BUG_ON(s->uptodate < disks);
2569         /* Want to check and possibly repair P and Q.
2570          * However there could be one 'failed' device, in which
2571          * case we can only check one of them, possibly using the
2572          * other to generate missing data
2573          */
2574
2575         /* If !tmp_page, we cannot do the calculations,
2576          * but as we have set STRIPE_HANDLE, we will soon be called
2577          * by stripe_handle with a tmp_page - just wait until then.
2578          */
2579         if (tmp_page) {
2580                 if (s->failed == r6s->q_failed) {
2581                         /* The only possible failed device holds 'Q', so it
2582                          * makes sense to check P (If anything else were failed,
2583                          * we would have used P to recreate it).
2584                          */
2585                         compute_block_1(sh, pd_idx, 1);
2586                         if (!page_is_zero(sh->dev[pd_idx].page)) {
2587                                 compute_block_1(sh, pd_idx, 0);
2588                                 update_p = 1;
2589                         }
2590                 }
2591                 if (!r6s->q_failed && s->failed < 2) {
2592                         /* q is not failed, and we didn't use it to generate
2593                          * anything, so it makes sense to check it
2594                          */
2595                         memcpy(page_address(tmp_page),
2596                                page_address(sh->dev[qd_idx].page),
2597                                STRIPE_SIZE);
2598                         compute_parity6(sh, UPDATE_PARITY);
2599                         if (memcmp(page_address(tmp_page),
2600                                    page_address(sh->dev[qd_idx].page),
2601                                    STRIPE_SIZE) != 0) {
2602                                 clear_bit(STRIPE_INSYNC, &sh->state);
2603                                 update_q = 1;
2604                         }
2605                 }
2606                 if (update_p || update_q) {
2607                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2608                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2609                                 /* don't try to repair!! */
2610                                 update_p = update_q = 0;
2611                 }
2612
2613                 /* now write out any block on a failed drive,
2614                  * or P or Q if they need it
2615                  */
2616
2617                 if (s->failed == 2) {
2618                         dev = &sh->dev[r6s->failed_num[1]];
2619                         s->locked++;
2620                         set_bit(R5_LOCKED, &dev->flags);
2621                         set_bit(R5_Wantwrite, &dev->flags);
2622                 }
2623                 if (s->failed >= 1) {
2624                         dev = &sh->dev[r6s->failed_num[0]];
2625                         s->locked++;
2626                         set_bit(R5_LOCKED, &dev->flags);
2627                         set_bit(R5_Wantwrite, &dev->flags);
2628                 }
2629
2630                 if (update_p) {
2631                         dev = &sh->dev[pd_idx];
2632                         s->locked++;
2633                         set_bit(R5_LOCKED, &dev->flags);
2634                         set_bit(R5_Wantwrite, &dev->flags);
2635                 }
2636                 if (update_q) {
2637                         dev = &sh->dev[qd_idx];
2638                         s->locked++;
2639                         set_bit(R5_LOCKED, &dev->flags);
2640                         set_bit(R5_Wantwrite, &dev->flags);
2641                 }
2642                 clear_bit(STRIPE_DEGRADED, &sh->state);
2643
2644                 set_bit(STRIPE_INSYNC, &sh->state);
2645         }
2646 }
2647
2648 static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
2649                                 struct r6_state *r6s)
2650 {
2651         int i;
2652
2653         /* We have read all the blocks in this stripe and now we need to
2654          * copy some of them into a target stripe for expand.
2655          */
2656         struct dma_async_tx_descriptor *tx = NULL;
2657         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2658         for (i = 0; i < sh->disks; i++)
2659                 if (i != sh->pd_idx && (r6s && i != r6s->qd_idx)) {
2660                         int dd_idx, pd_idx, j;
2661                         struct stripe_head *sh2;
2662
2663                         sector_t bn = compute_blocknr(sh, i);
2664                         sector_t s = raid5_compute_sector(bn, conf->raid_disks,
2665                                                 conf->raid_disks -
2666                                                 conf->max_degraded, &dd_idx,
2667                                                 &pd_idx, conf);
2668                         sh2 = get_active_stripe(conf, s, conf->raid_disks,
2669                                                 pd_idx, 1);
2670                         if (sh2 == NULL)
2671                                 /* so far only the early blocks of this stripe
2672                                  * have been requested.  When later blocks
2673                                  * get requested, we will try again
2674                                  */
2675                                 continue;
2676                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
2677                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
2678                                 /* must have already done this block */
2679                                 release_stripe(sh2);
2680                                 continue;
2681                         }
2682
2683                         /* place all the copies on one channel */
2684                         tx = async_memcpy(sh2->dev[dd_idx].page,
2685                                 sh->dev[i].page, 0, 0, STRIPE_SIZE,
2686                                 ASYNC_TX_DEP_ACK, tx, NULL, NULL);
2687
2688                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
2689                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
2690                         for (j = 0; j < conf->raid_disks; j++)
2691                                 if (j != sh2->pd_idx &&
2692                                     (r6s && j != r6s->qd_idx) &&
2693                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
2694                                         break;
2695                         if (j == conf->raid_disks) {
2696                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
2697                                 set_bit(STRIPE_HANDLE, &sh2->state);
2698                         }
2699                         release_stripe(sh2);
2700
2701                         /* done submitting copies, wait for them to complete */
2702                         if (i + 1 >= sh->disks) {
2703                                 async_tx_ack(tx);
2704                                 dma_wait_for_async_tx(tx);
2705                         }
2706                 }
2707 }
2708
2709 /*
2710  * handle_stripe - do things to a stripe.
2711  *
2712  * We lock the stripe and then examine the state of various bits
2713  * to see what needs to be done.
2714  * Possible results:
2715  *    return some read request which now have data
2716  *    return some write requests which are safely on disc
2717  *    schedule a read on some buffers
2718  *    schedule a write of some buffers
2719  *    return confirmation of parity correctness
2720  *
2721  * buffers are taken off read_list or write_list, and bh_cache buffers
2722  * get BH_Lock set before the stripe lock is released.
2723  *
2724  */
2725
2726 static void handle_stripe5(struct stripe_head *sh)
2727 {
2728         raid5_conf_t *conf = sh->raid_conf;
2729         int disks = sh->disks, i;
2730         struct bio *return_bi = NULL;
2731         struct stripe_head_state s;
2732         struct r5dev *dev;
2733         unsigned long pending = 0;
2734
2735         memset(&s, 0, sizeof(s));
2736         pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d "
2737                 "ops=%lx:%lx:%lx\n", (unsigned long long)sh->sector, sh->state,
2738                 atomic_read(&sh->count), sh->pd_idx,
2739                 sh->ops.pending, sh->ops.ack, sh->ops.complete);
2740
2741         spin_lock(&sh->lock);
2742         clear_bit(STRIPE_HANDLE, &sh->state);
2743         clear_bit(STRIPE_DELAYED, &sh->state);
2744
2745         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
2746         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2747         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
2748         /* Now to look around and see what can be done */
2749
2750         rcu_read_lock();
2751         for (i=disks; i--; ) {
2752                 mdk_rdev_t *rdev;
2753                 struct r5dev *dev = &sh->dev[i];
2754                 clear_bit(R5_Insync, &dev->flags);
2755
2756                 pr_debug("check %d: state 0x%lx toread %p read %p write %p "
2757                         "written %p\n", i, dev->flags, dev->toread, dev->read,
2758                         dev->towrite, dev->written);
2759
2760                 /* maybe we can request a biofill operation
2761                  *
2762                  * new wantfill requests are only permitted while
2763                  * STRIPE_OP_BIOFILL is clear
2764                  */
2765                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
2766                         !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
2767                         set_bit(R5_Wantfill, &dev->flags);
2768
2769                 /* now count some things */
2770                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
2771                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
2772                 if (test_bit(R5_Wantcompute, &dev->flags)) s.compute++;
2773
2774                 if (test_bit(R5_Wantfill, &dev->flags))
2775                         s.to_fill++;
2776                 else if (dev->toread)
2777                         s.to_read++;
2778                 if (dev->towrite) {
2779                         s.to_write++;
2780                         if (!test_bit(R5_OVERWRITE, &dev->flags))
2781                                 s.non_overwrite++;
2782                 }
2783                 if (dev->written)
2784                         s.written++;
2785                 rdev = rcu_dereference(conf->disks[i].rdev);
2786                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
2787                         /* The ReadError flag will just be confusing now */
2788                         clear_bit(R5_ReadError, &dev->flags);
2789                         clear_bit(R5_ReWrite, &dev->flags);
2790                 }
2791                 if (!rdev || !test_bit(In_sync, &rdev->flags)
2792                     || test_bit(R5_ReadError, &dev->flags)) {
2793                         s.failed++;
2794                         s.failed_num = i;
2795                 } else
2796                         set_bit(R5_Insync, &dev->flags);
2797         }
2798         rcu_read_unlock();
2799
2800         if (s.to_fill && !test_and_set_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
2801                 sh->ops.count++;
2802
2803         pr_debug("locked=%d uptodate=%d to_read=%d"
2804                 " to_write=%d failed=%d failed_num=%d\n",
2805                 s.locked, s.uptodate, s.to_read, s.to_write,
2806                 s.failed, s.failed_num);
2807         /* check if the array has lost two devices and, if so, some requests might
2808          * need to be failed
2809          */
2810         if (s.failed > 1 && s.to_read+s.to_write+s.written)
2811                 handle_requests_to_failed_array(conf, sh, &s, disks,
2812                                                 &return_bi);
2813         if (s.failed > 1 && s.syncing) {
2814                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
2815                 clear_bit(STRIPE_SYNCING, &sh->state);
2816                 s.syncing = 0;
2817         }
2818
2819         /* might be able to return some write requests if the parity block
2820          * is safe, or on a failed drive
2821          */
2822         dev = &sh->dev[sh->pd_idx];
2823         if ( s.written &&
2824              ((test_bit(R5_Insync, &dev->flags) &&
2825                !test_bit(R5_LOCKED, &dev->flags) &&
2826                test_bit(R5_UPTODATE, &dev->flags)) ||
2827                (s.failed == 1 && s.failed_num == sh->pd_idx)))
2828                 handle_completed_write_requests(conf, sh, disks, &return_bi);
2829
2830         /* Now we might consider reading some blocks, either to check/generate
2831          * parity, or to satisfy requests
2832          * or to load a block that is being partially written.
2833          */
2834         if (s.to_read || s.non_overwrite ||
2835             (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding ||
2836             test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
2837                 handle_issuing_new_read_requests5(sh, &s, disks);
2838
2839         /* Now we check to see if any write operations have recently
2840          * completed
2841          */
2842
2843         /* leave prexor set until postxor is done, allows us to distinguish
2844          * a rmw from a rcw during biodrain
2845          */
2846         if (test_bit(STRIPE_OP_PREXOR, &sh->ops.complete) &&
2847                 test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
2848
2849                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
2850                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.ack);
2851                 clear_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
2852
2853                 for (i = disks; i--; )
2854                         clear_bit(R5_Wantprexor, &sh->dev[i].flags);
2855         }
2856
2857         /* if only POSTXOR is set then this is an 'expand' postxor */
2858         if (test_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete) &&
2859                 test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
2860
2861                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
2862                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.ack);
2863                 clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
2864
2865                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
2866                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
2867                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
2868
2869                 /* All the 'written' buffers and the parity block are ready to
2870                  * be written back to disk
2871                  */
2872                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
2873                 for (i = disks; i--; ) {
2874                         dev = &sh->dev[i];
2875                         if (test_bit(R5_LOCKED, &dev->flags) &&
2876                                 (i == sh->pd_idx || dev->written)) {
2877                                 pr_debug("Writing block %d\n", i);
2878                                 set_bit(R5_Wantwrite, &dev->flags);
2879                                 if (!test_and_set_bit(
2880                                     STRIPE_OP_IO, &sh->ops.pending))
2881                                         sh->ops.count++;
2882                                 if (!test_bit(R5_Insync, &dev->flags) ||
2883                                     (i == sh->pd_idx && s.failed == 0))
2884                                         set_bit(STRIPE_INSYNC, &sh->state);
2885                         }
2886                 }
2887                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2888                         atomic_dec(&conf->preread_active_stripes);
2889                         if (atomic_read(&conf->preread_active_stripes) <
2890                                 IO_THRESHOLD)
2891                                 md_wakeup_thread(conf->mddev->thread);
2892                 }
2893         }
2894
2895         /* Now to consider new write requests and what else, if anything
2896          * should be read.  We do not handle new writes when:
2897          * 1/ A 'write' operation (copy+xor) is already in flight.
2898          * 2/ A 'check' operation is in flight, as it may clobber the parity
2899          *    block.
2900          */
2901         if (s.to_write && !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending) &&
2902                           !test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
2903                 handle_issuing_new_write_requests5(conf, sh, &s, disks);
2904
2905         /* maybe we need to check and possibly fix the parity for this stripe
2906          * Any reads will already have been scheduled, so we just see if enough
2907          * data is available.  The parity check is held off while parity
2908          * dependent operations are in flight.
2909          */
2910         if ((s.syncing && s.locked == 0 &&
2911              !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
2912              !test_bit(STRIPE_INSYNC, &sh->state)) ||
2913               test_bit(STRIPE_OP_CHECK, &sh->ops.pending) ||
2914               test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending))
2915                 handle_parity_checks5(conf, sh, &s, disks);
2916
2917         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
2918                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
2919                 clear_bit(STRIPE_SYNCING, &sh->state);
2920         }
2921
2922         /* If the failed drive is just a ReadError, then we might need to progress
2923          * the repair/check process
2924          */
2925         if (s.failed == 1 && !conf->mddev->ro &&
2926             test_bit(R5_ReadError, &sh->dev[s.failed_num].flags)
2927             && !test_bit(R5_LOCKED, &sh->dev[s.failed_num].flags)
2928             && test_bit(R5_UPTODATE, &sh->dev[s.failed_num].flags)
2929                 ) {
2930                 dev = &sh->dev[s.failed_num];
2931                 if (!test_bit(R5_ReWrite, &dev->flags)) {
2932                         set_bit(R5_Wantwrite, &dev->flags);
2933                         set_bit(R5_ReWrite, &dev->flags);
2934                         set_bit(R5_LOCKED, &dev->flags);
2935                         s.locked++;
2936                 } else {
2937                         /* let's read it back */
2938                         set_bit(R5_Wantread, &dev->flags);
2939                         set_bit(R5_LOCKED, &dev->flags);
2940                         s.locked++;
2941                 }
2942         }
2943
2944         /* Finish postxor operations initiated by the expansion
2945          * process
2946          */
2947         if (test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete) &&
2948                 !test_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending)) {
2949
2950                 clear_bit(STRIPE_EXPANDING, &sh->state);
2951
2952                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
2953                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
2954                 clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
2955
2956                 for (i = conf->raid_disks; i--; ) {
2957                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
2958                         if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
2959                                 sh->ops.count++;
2960                 }
2961         }
2962
2963         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
2964                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2965                 /* Need to write out all blocks after computing parity */
2966                 sh->disks = conf->raid_disks;
2967                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
2968                         conf->raid_disks);
2969                 s.locked += handle_write_operations5(sh, 0, 1);
2970         } else if (s.expanded &&
2971                 !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
2972                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
2973                 atomic_dec(&conf->reshape_stripes);
2974                 wake_up(&conf->wait_for_overlap);
2975                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
2976         }
2977
2978         if (s.expanding && s.locked == 0)
2979                 handle_stripe_expansion(conf, sh, NULL);
2980
2981         if (sh->ops.count)
2982                 pending = get_stripe_work(sh);
2983
2984         spin_unlock(&sh->lock);
2985
2986         if (pending)
2987                 raid5_run_ops(sh, pending);
2988
2989         return_io(return_bi);
2990
2991         for (i=disks; i-- ;) {
2992                 int rw;
2993                 struct bio *bi;
2994                 mdk_rdev_t *rdev;
2995                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
2996                         rw = WRITE;
2997                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
2998                         rw = READ;
2999                 else
3000                         continue;
3001
3002                 bi = &sh->dev[i].req;
3003
3004                 bi->bi_rw = rw;
3005                 if (rw == WRITE)
3006                         bi->bi_end_io = raid5_end_write_request;
3007                 else
3008                         bi->bi_end_io = raid5_end_read_request;
3009
3010                 rcu_read_lock();
3011                 rdev = rcu_dereference(conf->disks[i].rdev);
3012                 if (rdev && test_bit(Faulty, &rdev->flags))
3013                         rdev = NULL;
3014                 if (rdev)
3015                         atomic_inc(&rdev->nr_pending);
3016                 rcu_read_unlock();
3017
3018                 if (rdev) {
3019                         if (s.syncing || s.expanding || s.expanded)
3020                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
3021
3022                         bi->bi_bdev = rdev->bdev;
3023                         pr_debug("for %llu schedule op %ld on disc %d\n",
3024                                 (unsigned long long)sh->sector, bi->bi_rw, i);
3025                         atomic_inc(&sh->count);
3026                         bi->bi_sector = sh->sector + rdev->data_offset;
3027                         bi->bi_flags = 1 << BIO_UPTODATE;
3028                         bi->bi_vcnt = 1;
3029                         bi->bi_max_vecs = 1;
3030                         bi->bi_idx = 0;
3031                         bi->bi_io_vec = &sh->dev[i].vec;
3032                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
3033                         bi->bi_io_vec[0].bv_offset = 0;
3034                         bi->bi_size = STRIPE_SIZE;
3035                         bi->bi_next = NULL;
3036                         if (rw == WRITE &&
3037                             test_bit(R5_ReWrite, &sh->dev[i].flags))
3038                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
3039                         generic_make_request(bi);
3040                 } else {
3041                         if (rw == WRITE)
3042                                 set_bit(STRIPE_DEGRADED, &sh->state);
3043                         pr_debug("skip op %ld on disc %d for sector %llu\n",
3044                                 bi->bi_rw, i, (unsigned long long)sh->sector);
3045                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
3046                         set_bit(STRIPE_HANDLE, &sh->state);
3047                 }
3048         }
3049 }
3050
3051 static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
3052 {
3053         raid6_conf_t *conf = sh->raid_conf;
3054         int disks = sh->disks;
3055         struct bio *return_bi = NULL;
3056         int i, pd_idx = sh->pd_idx;
3057         struct stripe_head_state s;
3058         struct r6_state r6s;
3059         struct r5dev *dev, *pdev, *qdev;
3060
3061         r6s.qd_idx = raid6_next_disk(pd_idx, disks);
3062         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3063                 "pd_idx=%d, qd_idx=%d\n",
3064                (unsigned long long)sh->sector, sh->state,
3065                atomic_read(&sh->count), pd_idx, r6s.qd_idx);
3066         memset(&s, 0, sizeof(s));
3067
3068         spin_lock(&sh->lock);
3069         clear_bit(STRIPE_HANDLE, &sh->state);
3070         clear_bit(STRIPE_DELAYED, &sh->state);
3071
3072         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
3073         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3074         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3075         /* Now to look around and see what can be done */
3076
3077         rcu_read_lock();
3078         for (i=disks; i--; ) {
3079                 mdk_rdev_t *rdev;
3080                 dev = &sh->dev[i];
3081                 clear_bit(R5_Insync, &dev->flags);
3082
3083                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3084                         i, dev->flags, dev->toread, dev->towrite, dev->written);
3085                 /* maybe we can reply to a read */
3086                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
3087                         struct bio *rbi, *rbi2;
3088                         pr_debug("Return read for disc %d\n", i);
3089                         spin_lock_irq(&conf->device_lock);
3090                         rbi = dev->toread;
3091                         dev->toread = NULL;
3092                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
3093                                 wake_up(&conf->wait_for_overlap);
3094                         spin_unlock_irq(&conf->device_lock);
3095                         while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
3096                                 copy_data(0, rbi, dev->page, dev->sector);
3097                                 rbi2 = r5_next_bio(rbi, dev->sector);
3098                                 spin_lock_irq(&conf->device_lock);
3099                                 if (--rbi->bi_phys_segments == 0) {
3100                                         rbi->bi_next = return_bi;
3101                                         return_bi = rbi;
3102                                 }
3103                                 spin_unlock_irq(&conf->device_lock);
3104                                 rbi = rbi2;
3105                         }
3106                 }
3107
3108                 /* now count some things */
3109                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
3110                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
3111
3112
3113                 if (dev->toread)
3114                         s.to_read++;
3115                 if (dev->towrite) {
3116                         s.to_write++;
3117                         if (!test_bit(R5_OVERWRITE, &dev->flags))
3118                                 s.non_overwrite++;
3119                 }
3120                 if (dev->written)
3121                         s.written++;
3122                 rdev = rcu_dereference(conf->disks[i].rdev);
3123                 if (!rdev || !test_bit(In_sync, &rdev->flags)) {
3124                         /* The ReadError flag will just be confusing now */
3125                         clear_bit(R5_ReadError, &dev->flags);
3126                         clear_bit(R5_ReWrite, &dev->flags);
3127                 }
3128                 if (!rdev || !test_bit(In_sync, &rdev->flags)
3129                     || test_bit(R5_ReadError, &dev->flags)) {
3130                         if (s.failed < 2)
3131                                 r6s.failed_num[s.failed] = i;
3132                         s.failed++;
3133                 } else
3134                         set_bit(R5_Insync, &dev->flags);
3135         }
3136         rcu_read_unlock();
3137         pr_debug("locked=%d uptodate=%d to_read=%d"
3138                " to_write=%d failed=%d failed_num=%d,%d\n",
3139                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3140                r6s.failed_num[0], r6s.failed_num[1]);
3141         /* check if the array has lost >2 devices and, if so, some requests
3142          * might need to be failed
3143          */
3144         if (s.failed > 2 && s.to_read+s.to_write+s.written)
3145                 handle_requests_to_failed_array(conf, sh, &s, disks,
3146                                                 &return_bi);
3147         if (s.failed > 2 && s.syncing) {
3148                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
3149                 clear_bit(STRIPE_SYNCING, &sh->state);
3150                 s.syncing = 0;
3151         }
3152
3153         /*
3154          * might be able to return some write requests if the parity blocks
3155          * are safe, or on a failed drive
3156          */
3157         pdev = &sh->dev[pd_idx];
3158         r6s.p_failed = (s.failed >= 1 && r6s.failed_num[0] == pd_idx)
3159                 || (s.failed >= 2 && r6s.failed_num[1] == pd_idx);
3160         qdev = &sh->dev[r6s.qd_idx];
3161         r6s.q_failed = (s.failed >= 1 && r6s.failed_num[0] == r6s.qd_idx)
3162                 || (s.failed >= 2 && r6s.failed_num[1] == r6s.qd_idx);
3163
3164         if ( s.written &&
3165              ( r6s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3166                              && !test_bit(R5_LOCKED, &pdev->flags)
3167                              && test_bit(R5_UPTODATE, &pdev->flags)))) &&
3168              ( r6s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3169                              && !test_bit(R5_LOCKED, &qdev->flags)
3170                              && test_bit(R5_UPTODATE, &qdev->flags)))))
3171                 handle_completed_write_requests(conf, sh, disks, &return_bi);
3172
3173         /* Now we might consider reading some blocks, either to check/generate
3174          * parity, or to satisfy requests
3175          * or to load a block that is being partially written.
3176          */
3177         if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
3178             (s.syncing && (s.uptodate < disks)) || s.expanding)
3179                 handle_issuing_new_read_requests6(sh, &s, &r6s, disks);
3180
3181         /* now to consider writing and what else, if anything should be read */
3182         if (s.to_write)
3183                 handle_issuing_new_write_requests6(conf, sh, &s, &r6s, disks);
3184
3185         /* maybe we need to check and possibly fix the parity for this stripe
3186          * Any reads will already have been scheduled, so we just see if enough
3187          * data is available
3188          */
3189         if (s.syncing && s.locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state))
3190                 handle_parity_checks6(conf, sh, &s, &r6s, tmp_page, disks);
3191
3192         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
3193                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
3194                 clear_bit(STRIPE_SYNCING, &sh->state);
3195         }
3196
3197         /* If the failed drives are just a ReadError, then we might need
3198          * to progress the repair/check process
3199          */
3200         if (s.failed <= 2 && !conf->mddev->ro)
3201                 for (i = 0; i < s.failed; i++) {
3202                         dev = &sh->dev[r6s.failed_num[i]];
3203                         if (test_bit(R5_ReadError, &dev->flags)
3204                             && !test_bit(R5_LOCKED, &dev->flags)
3205                             && test_bit(R5_UPTODATE, &dev->flags)
3206                                 ) {
3207                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3208                                         set_bit(R5_Wantwrite, &dev->flags);
3209                                         set_bit(R5_ReWrite, &dev->flags);
3210                                         set_bit(R5_LOCKED, &dev->flags);
3211                                 } else {
3212                                         /* let's read it back */
3213                                         set_bit(R5_Wantread, &dev->flags);
3214                                         set_bit(R5_LOCKED, &dev->flags);
3215                                 }
3216                         }
3217                 }
3218
3219         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
3220                 /* Need to write out all blocks after computing P&Q */
3221                 sh->disks = conf->raid_disks;
3222                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
3223                                              conf->raid_disks);
3224                 compute_parity6(sh, RECONSTRUCT_WRITE);
3225                 for (i = conf->raid_disks ; i-- ;  ) {
3226                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3227                         s.locked++;
3228                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3229                 }
3230                 clear_bit(STRIPE_EXPANDING, &sh->state);
3231         } else if (s.expanded) {
3232                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3233                 atomic_dec(&conf->reshape_stripes);
3234                 wake_up(&conf->wait_for_overlap);
3235                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3236         }
3237
3238         if (s.expanding && s.locked == 0)
3239                 handle_stripe_expansion(conf, sh, &r6s);
3240
3241         spin_unlock(&sh->lock);
3242
3243         return_io(return_bi);
3244
3245         for (i=disks; i-- ;) {
3246                 int rw;
3247                 struct bio *bi;
3248                 mdk_rdev_t *rdev;
3249                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
3250                         rw = WRITE;
3251                 else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
3252                         rw = READ;
3253                 else
3254                         continue;
3255
3256                 bi = &sh->dev[i].req;
3257
3258                 bi->bi_rw = rw;
3259                 if (rw == WRITE)
3260                         bi->bi_end_io = raid5_end_write_request;
3261                 else
3262                         bi->bi_end_io = raid5_end_read_request;
3263
3264                 rcu_read_lock();
3265                 rdev = rcu_dereference(conf->disks[i].rdev);
3266                 if (rdev && test_bit(Faulty, &rdev->flags))
3267                         rdev = NULL;
3268                 if (rdev)
3269                         atomic_inc(&rdev->nr_pending);
3270                 rcu_read_unlock();
3271
3272                 if (rdev) {
3273                         if (s.syncing || s.expanding || s.expanded)
3274                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
3275
3276                         bi->bi_bdev = rdev->bdev;
3277                         pr_debug("for %llu schedule op %ld on disc %d\n",
3278                                 (unsigned long long)sh->sector, bi->bi_rw, i);
3279                         atomic_inc(&sh->count);
3280                         bi->bi_sector = sh->sector + rdev->data_offset;
3281                         bi->bi_flags = 1 << BIO_UPTODATE;
3282                         bi->bi_vcnt = 1;
3283                         bi->bi_max_vecs = 1;
3284                         bi->bi_idx = 0;
3285                         bi->bi_io_vec = &sh->dev[i].vec;
3286                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
3287                         bi->bi_io_vec[0].bv_offset = 0;
3288                         bi->bi_size = STRIPE_SIZE;
3289                         bi->bi_next = NULL;
3290                         if (rw == WRITE &&
3291                             test_bit(R5_ReWrite, &sh->dev[i].flags))
3292                                 atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
3293                         generic_make_request(bi);
3294                 } else {
3295                         if (rw == WRITE)
3296                                 set_bit(STRIPE_DEGRADED, &sh->state);
3297                         pr_debug("skip op %ld on disc %d for sector %llu\n",
3298                                 bi->bi_rw, i, (unsigned long long)sh->sector);
3299                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
3300                         set_bit(STRIPE_HANDLE, &sh->state);
3301                 }
3302         }
3303 }
3304
3305 static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
3306 {
3307         if (sh->raid_conf->level == 6)
3308                 handle_stripe6(sh, tmp_page);
3309         else
3310                 handle_stripe5(sh);
3311 }
3312
3313
3314
3315 static void raid5_activate_delayed(raid5_conf_t *conf)
3316 {
3317         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3318                 while (!list_empty(&conf->delayed_list)) {
3319                         struct list_head *l = conf->delayed_list.next;
3320                         struct stripe_head *sh;
3321                         sh = list_entry(l, struct stripe_head, lru);
3322                         list_del_init(l);
3323                         clear_bit(STRIPE_DELAYED, &sh->state);
3324                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3325                                 atomic_inc(&conf->preread_active_stripes);
3326                         list_add_tail(&sh->lru, &conf->handle_list);
3327                 }
3328         }
3329 }
3330
3331 static void activate_bit_delay(raid5_conf_t *conf)
3332 {
3333         /* device_lock is held */
3334         struct list_head head;
3335         list_add(&head, &conf->bitmap_list);
3336         list_del_init(&conf->bitmap_list);
3337         while (!list_empty(&head)) {
3338                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3339                 list_del_init(&sh->lru);
3340                 atomic_inc(&sh->count);
3341                 __release_stripe(conf, sh);
3342         }
3343 }
3344
3345 static void unplug_slaves(mddev_t *mddev)
3346 {
3347         raid5_conf_t *conf = mddev_to_conf(mddev);
3348         int i;
3349
3350         rcu_read_lock();
3351         for (i=0; i<mddev->raid_disks; i++) {
3352                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
3353                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
3354                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
3355
3356                         atomic_inc(&rdev->nr_pending);
3357                         rcu_read_unlock();
3358
3359                         if (r_queue->unplug_fn)
3360                                 r_queue->unplug_fn(r_queue);
3361
3362                         rdev_dec_pending(rdev, mddev);
3363                         rcu_read_lock();
3364                 }
3365         }
3366         rcu_read_unlock();
3367 }
3368
3369 static void raid5_unplug_device(request_queue_t *q)
3370 {
3371         mddev_t *mddev = q->queuedata;
3372         raid5_conf_t *conf = mddev_to_conf(mddev);
3373         unsigned long flags;
3374
3375         spin_lock_irqsave(&conf->device_lock, flags);
3376
3377         if (blk_remove_plug(q)) {
3378                 conf->seq_flush++;
3379                 raid5_activate_delayed(conf);
3380         }
3381         md_wakeup_thread(mddev->thread);
3382
3383         spin_unlock_irqrestore(&conf->device_lock, flags);
3384
3385         unplug_slaves(mddev);
3386 }
3387
3388 static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk,
3389                              sector_t *error_sector)
3390 {
3391         mddev_t *mddev = q->queuedata;
3392         raid5_conf_t *conf = mddev_to_conf(mddev);
3393         int i, ret = 0;
3394
3395         rcu_read_lock();
3396         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
3397                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
3398                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
3399                         struct block_device *bdev = rdev->bdev;
3400                         request_queue_t *r_queue = bdev_get_queue(bdev);
3401
3402                         if (!r_queue->issue_flush_fn)
3403                                 ret = -EOPNOTSUPP;
3404                         else {
3405                                 atomic_inc(&rdev->nr_pending);
3406                                 rcu_read_unlock();
3407                                 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
3408                                                               error_sector);
3409                                 rdev_dec_pending(rdev, mddev);
3410                                 rcu_read_lock();
3411                         }
3412                 }
3413         }
3414         rcu_read_unlock();
3415         return ret;
3416 }
3417
3418 static int raid5_congested(void *data, int bits)
3419 {
3420         mddev_t *mddev = data;
3421         raid5_conf_t *conf = mddev_to_conf(mddev);
3422
3423         /* No difference between reads and writes.  Just check
3424          * how busy the stripe_cache is
3425          */
3426         if (conf->inactive_blocked)
3427                 return 1;
3428         if (conf->quiesce)
3429                 return 1;
3430         if (list_empty_careful(&conf->inactive_list))
3431                 return 1;
3432
3433         return 0;
3434 }
3435
3436 /* We want read requests to align with chunks where possible,
3437  * but write requests don't need to.
3438  */
3439 static int raid5_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
3440 {
3441         mddev_t *mddev = q->queuedata;
3442         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3443         int max;
3444         unsigned int chunk_sectors = mddev->chunk_size >> 9;
3445         unsigned int bio_sectors = bio->bi_size >> 9;
3446
3447         if (bio_data_dir(bio) == WRITE)
3448                 return biovec->bv_len; /* always allow writes to be mergeable */
3449
3450         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3451         if (max < 0) max = 0;
3452         if (max <= biovec->bv_len && bio_sectors == 0)
3453                 return biovec->bv_len;
3454         else
3455                 return max;
3456 }
3457
3458
3459 static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
3460 {
3461         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3462         unsigned int chunk_sectors = mddev->chunk_size >> 9;
3463         unsigned int bio_sectors = bio->bi_size >> 9;
3464
3465         return  chunk_sectors >=
3466                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3467 }
3468
3469 /*
3470  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3471  *  later sampled by raid5d.
3472  */
3473 static void add_bio_to_retry(struct bio *bi,raid5_conf_t *conf)
3474 {
3475         unsigned long flags;
3476
3477         spin_lock_irqsave(&conf->device_lock, flags);
3478
3479         bi->bi_next = conf->retry_read_aligned_list;
3480         conf->retry_read_aligned_list = bi;
3481
3482         spin_unlock_irqrestore(&conf->device_lock, flags);
3483         md_wakeup_thread(conf->mddev->thread);
3484 }
3485
3486
3487 static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
3488 {
3489         struct bio *bi;
3490
3491         bi = conf->retry_read_aligned;
3492         if (bi) {
3493                 conf->retry_read_aligned = NULL;
3494                 return bi;
3495         }
3496         bi = conf->retry_read_aligned_list;
3497         if(bi) {
3498                 conf->retry_read_aligned_list = bi->bi_next;
3499                 bi->bi_next = NULL;
3500                 bi->bi_phys_segments = 1; /* biased count of active stripes */
3501                 bi->bi_hw_segments = 0; /* count of processed stripes */
3502         }
3503
3504         return bi;
3505 }
3506
3507
3508 /*
3509  *  The "raid5_align_endio" should check if the read succeeded and if it
3510  *  did, call bio_endio on the original bio (having bio_put the new bio
3511  *  first).
3512  *  If the read failed..
3513  */
3514 static int raid5_align_endio(struct bio *bi, unsigned int bytes, int error)
3515 {
3516         struct bio* raid_bi  = bi->bi_private;
3517         mddev_t *mddev;
3518         raid5_conf_t *conf;
3519         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3520         mdk_rdev_t *rdev;
3521
3522         if (bi->bi_size)
3523                 return 1;
3524         bio_put(bi);
3525
3526         mddev = raid_bi->bi_bdev->bd_disk->queue->queuedata;
3527         conf = mddev_to_conf(mddev);
3528         rdev = (void*)raid_bi->bi_next;
3529         raid_bi->bi_next = NULL;
3530
3531         rdev_dec_pending(rdev, conf->mddev);
3532
3533         if (!error && uptodate) {
3534                 bio_endio(raid_bi, bytes, 0);
3535                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3536                         wake_up(&conf->wait_for_stripe);
3537                 return 0;
3538         }
3539
3540
3541         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3542
3543         add_bio_to_retry(raid_bi, conf);
3544         return 0;
3545 }
3546
3547 static int bio_fits_rdev(struct bio *bi)
3548 {
3549         request_queue_t *q = bdev_get_queue(bi->bi_bdev);
3550
3551         if ((bi->bi_size>>9) > q->max_sectors)
3552                 return 0;
3553         blk_recount_segments(q, bi);
3554         if (bi->bi_phys_segments > q->max_phys_segments ||
3555             bi->bi_hw_segments > q->max_hw_segments)
3556                 return 0;
3557
3558         if (q->merge_bvec_fn)
3559                 /* it's too hard to apply the merge_bvec_fn at this stage,
3560                  * just just give up
3561                  */
3562                 return 0;
3563
3564         return 1;
3565 }
3566
3567
3568 static int chunk_aligned_read(request_queue_t *q, struct bio * raid_bio)
3569 {
3570         mddev_t *mddev = q->queuedata;
3571         raid5_conf_t *conf = mddev_to_conf(mddev);
3572         const unsigned int raid_disks = conf->raid_disks;
3573         const unsigned int data_disks = raid_disks - conf->max_degraded;
3574         unsigned int dd_idx, pd_idx;
3575         struct bio* align_bi;
3576         mdk_rdev_t *rdev;
3577
3578         if (!in_chunk_boundary(mddev, raid_bio)) {
3579                 pr_debug("chunk_aligned_read : non aligned\n");
3580                 return 0;
3581         }
3582         /*
3583          * use bio_clone to make a copy of the bio
3584          */
3585         align_bi = bio_clone(raid_bio, GFP_NOIO);
3586         if (!align_bi)
3587                 return 0;
3588         /*
3589          *   set bi_end_io to a new function, and set bi_private to the
3590          *     original bio.
3591          */
3592         align_bi->bi_end_io  = raid5_align_endio;
3593         align_bi->bi_private = raid_bio;
3594         /*
3595          *      compute position
3596          */
3597         align_bi->bi_sector =  raid5_compute_sector(raid_bio->bi_sector,
3598                                         raid_disks,
3599                                         data_disks,
3600                                         &dd_idx,
3601                                         &pd_idx,
3602                                         conf);
3603
3604         rcu_read_lock();
3605         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3606         if (rdev && test_bit(In_sync, &rdev->flags)) {
3607                 atomic_inc(&rdev->nr_pending);
3608                 rcu_read_unlock();
3609                 raid_bio->bi_next = (void*)rdev;
3610                 align_bi->bi_bdev =  rdev->bdev;
3611                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
3612                 align_bi->bi_sector += rdev->data_offset;
3613
3614                 if (!bio_fits_rdev(align_bi)) {
3615                         /* too big in some way */
3616                         bio_put(align_bi);
3617                         rdev_dec_pending(rdev, mddev);
3618                         return 0;
3619                 }
3620
3621                 spin_lock_irq(&conf->device_lock);
3622                 wait_event_lock_irq(conf->wait_for_stripe,
3623                                     conf->quiesce == 0,
3624                                     conf->device_lock, /* nothing */);
3625                 atomic_inc(&conf->active_aligned_reads);
3626                 spin_unlock_irq(&conf->device_lock);
3627
3628                 generic_make_request(align_bi);
3629                 return 1;
3630         } else {
3631                 rcu_read_unlock();
3632                 bio_put(align_bi);
3633                 return 0;
3634         }
3635 }
3636
3637
3638 static int make_request(request_queue_t *q, struct bio * bi)
3639 {
3640         mddev_t *mddev = q->queuedata;
3641         raid5_conf_t *conf = mddev_to_conf(mddev);
3642         unsigned int dd_idx, pd_idx;
3643         sector_t new_sector;
3644         sector_t logical_sector, last_sector;
3645         struct stripe_head *sh;
3646         const int rw = bio_data_dir(bi);
3647         int remaining;
3648
3649         if (unlikely(bio_barrier(bi))) {
3650                 bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
3651                 return 0;
3652         }
3653
3654         md_write_start(mddev, bi);
3655
3656         disk_stat_inc(mddev->gendisk, ios[rw]);
3657         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
3658
3659         if (rw == READ &&
3660              mddev->reshape_position == MaxSector &&
3661              chunk_aligned_read(q,bi))
3662                 return 0;
3663
3664         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
3665         last_sector = bi->bi_sector + (bi->bi_size>>9);
3666         bi->bi_next = NULL;
3667         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
3668
3669         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
3670                 DEFINE_WAIT(w);
3671                 int disks, data_disks;
3672
3673         retry:
3674                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
3675                 if (likely(conf->expand_progress == MaxSector))
3676                         disks = conf->raid_disks;
3677                 else {
3678                         /* spinlock is needed as expand_progress may be
3679                          * 64bit on a 32bit platform, and so it might be
3680                          * possible to see a half-updated value
3681                          * Ofcourse expand_progress could change after
3682                          * the lock is dropped, so once we get a reference
3683                          * to the stripe that we think it is, we will have
3684                          * to check again.
3685                          */
3686                         spin_lock_irq(&conf->device_lock);
3687                         disks = conf->raid_disks;
3688                         if (logical_sector >= conf->expand_progress)
3689                                 disks = conf->previous_raid_disks;
3690                         else {
3691                                 if (logical_sector >= conf->expand_lo) {
3692                                         spin_unlock_irq(&conf->device_lock);
3693                                         schedule();
3694                                         goto retry;
3695                                 }
3696                         }
3697                         spin_unlock_irq(&conf->device_lock);
3698                 }
3699                 data_disks = disks - conf->max_degraded;
3700
3701                 new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
3702                                                   &dd_idx, &pd_idx, conf);
3703                 pr_debug("raid5: make_request, sector %llu logical %llu\n",
3704                         (unsigned long long)new_sector,
3705                         (unsigned long long)logical_sector);
3706
3707                 sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
3708                 if (sh) {
3709                         if (unlikely(conf->expand_progress != MaxSector)) {
3710                                 /* expansion might have moved on while waiting for a
3711                                  * stripe, so we must do the range check again.
3712                                  * Expansion could still move past after this
3713                                  * test, but as we are holding a reference to
3714                                  * 'sh', we know that if that happens,
3715                                  *  STRIPE_EXPANDING will get set and the expansion
3716                                  * won't proceed until we finish with the stripe.
3717                                  */
3718                                 int must_retry = 0;
3719                                 spin_lock_irq(&conf->device_lock);
3720                                 if (logical_sector <  conf->expand_progress &&
3721                                     disks == conf->previous_raid_disks)
3722                                         /* mismatch, need to try again */
3723                                         must_retry = 1;
3724                                 spin_unlock_irq(&conf->device_lock);
3725                                 if (must_retry) {
3726                                         release_stripe(sh);
3727                                         goto retry;
3728                                 }
3729                         }
3730                         /* FIXME what if we get a false positive because these
3731                          * are being updated.
3732                          */
3733                         if (logical_sector >= mddev->suspend_lo &&
3734                             logical_sector < mddev->suspend_hi) {
3735                                 release_stripe(sh);
3736                                 schedule();
3737                                 goto retry;
3738                         }
3739
3740                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
3741                             !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
3742                                 /* Stripe is busy expanding or
3743                                  * add failed due to overlap.  Flush everything
3744                                  * and wait a while
3745                                  */
3746                                 raid5_unplug_device(mddev->queue);
3747                                 release_stripe(sh);
3748                                 schedule();
3749                                 goto retry;
3750                         }
3751                         finish_wait(&conf->wait_for_overlap, &w);
3752                         handle_stripe(sh, NULL);
3753                         release_stripe(sh);
3754                 } else {
3755                         /* cannot get stripe for read-ahead, just give-up */
3756                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
3757                         finish_wait(&conf->wait_for_overlap, &w);
3758                         break;
3759                 }
3760
3761         }
3762         spin_lock_irq(&conf->device_lock);
3763         remaining = --bi->bi_phys_segments;
3764         spin_unlock_irq(&conf->device_lock);
3765         if (remaining == 0) {
3766                 int bytes = bi->bi_size;
3767
3768                 if ( rw == WRITE )
3769                         md_write_end(mddev);
3770                 bi->bi_size = 0;
3771                 bi->bi_end_io(bi, bytes,
3772                               test_bit(BIO_UPTODATE, &bi->bi_flags)
3773                                 ? 0 : -EIO);
3774         }
3775         return 0;
3776 }
3777
3778 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
3779 {
3780         /* reshaping is quite different to recovery/resync so it is
3781          * handled quite separately ... here.
3782          *
3783          * On each call to sync_request, we gather one chunk worth of
3784          * destination stripes and flag them as expanding.
3785          * Then we find all the source stripes and request reads.
3786          * As the reads complete, handle_stripe will copy the data
3787          * into the destination stripe and release that stripe.
3788          */
3789         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3790         struct stripe_head *sh;
3791         int pd_idx;
3792         sector_t first_sector, last_sector;
3793         int raid_disks = conf->previous_raid_disks;
3794         int data_disks = raid_disks - conf->max_degraded;
3795         int new_data_disks = conf->raid_disks - conf->max_degraded;
3796         int i;
3797         int dd_idx;
3798         sector_t writepos, safepos, gap;
3799
3800         if (sector_nr == 0 &&
3801             conf->expand_progress != 0) {
3802                 /* restarting in the middle, skip the initial sectors */
3803                 sector_nr = conf->expand_progress;
3804                 sector_div(sector_nr, new_data_disks);
3805                 *skipped = 1;
3806                 return sector_nr;
3807         }
3808
3809         /* we update the metadata when there is more than 3Meg
3810          * in the block range (that is rather arbitrary, should
3811          * probably be time based) or when the data about to be
3812          * copied would over-write the source of the data at
3813          * the front of the range.
3814          * i.e. one new_stripe forward from expand_progress new_maps
3815          * to after where expand_lo old_maps to
3816          */
3817         writepos = conf->expand_progress +
3818                 conf->chunk_size/512*(new_data_disks);
3819         sector_div(writepos, new_data_disks);
3820         safepos = conf->expand_lo;
3821         sector_div(safepos, data_disks);
3822         gap = conf->expand_progress - conf->expand_lo;
3823
3824         if (writepos >= safepos ||
3825             gap > (new_data_disks)*3000*2 /*3Meg*/) {
3826                 /* Cannot proceed until we've updated the superblock... */
3827                 wait_event(conf->wait_for_overlap,
3828                            atomic_read(&conf->reshape_stripes)==0);
3829                 mddev->reshape_position = conf->expand_progress;
3830                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
3831                 md_wakeup_thread(mddev->thread);
3832                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
3833                            kthread_should_stop());
3834                 spin_lock_irq(&conf->device_lock);
3835                 conf->expand_lo = mddev->reshape_position;
3836                 spin_unlock_irq(&conf->device_lock);
3837                 wake_up(&conf->wait_for_overlap);
3838         }
3839
3840         for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
3841                 int j;
3842                 int skipped = 0;
3843                 pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
3844                 sh = get_active_stripe(conf, sector_nr+i,
3845                                        conf->raid_disks, pd_idx, 0);
3846                 set_bit(STRIPE_EXPANDING, &sh->state);
3847                 atomic_inc(&conf->reshape_stripes);
3848                 /* If any of this stripe is beyond the end of the old
3849                  * array, then we need to zero those blocks
3850                  */
3851                 for (j=sh->disks; j--;) {
3852                         sector_t s;
3853                         if (j == sh->pd_idx)
3854                                 continue;
3855                         if (conf->level == 6 &&
3856                             j == raid6_next_disk(sh->pd_idx, sh->disks))
3857                                 continue;
3858                         s = compute_blocknr(sh, j);
3859                         if (s < (mddev->array_size<<1)) {
3860                                 skipped = 1;
3861                                 continue;
3862                         }
3863                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
3864                         set_bit(R5_Expanded, &sh->dev[j].flags);
3865                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
3866                 }
3867                 if (!skipped) {
3868                         set_bit(STRIPE_EXPAND_READY, &sh->state);
3869                         set_bit(STRIPE_HANDLE, &sh->state);
3870                 }
3871                 release_stripe(sh);
3872         }
3873         spin_lock_irq(&conf->device_lock);
3874         conf->expand_progress = (sector_nr + i) * new_data_disks;
3875         spin_unlock_irq(&conf->device_lock);
3876         /* Ok, those stripe are ready. We can start scheduling
3877          * reads on the source stripes.
3878          * The source stripes are determined by mapping the first and last
3879          * block on the destination stripes.
3880          */
3881         first_sector =
3882                 raid5_compute_sector(sector_nr*(new_data_disks),
3883                                      raid_disks, data_disks,
3884                                      &dd_idx, &pd_idx, conf);
3885         last_sector =
3886                 raid5_compute_sector((sector_nr+conf->chunk_size/512)
3887                                      *(new_data_disks) -1,
3888                                      raid_disks, data_disks,
3889                                      &dd_idx, &pd_idx, conf);
3890         if (last_sector >= (mddev->size<<1))
3891                 last_sector = (mddev->size<<1)-1;
3892         while (first_sector <= last_sector) {
3893                 pd_idx = stripe_to_pdidx(first_sector, conf,
3894                                          conf->previous_raid_disks);
3895                 sh = get_active_stripe(conf, first_sector,
3896                                        conf->previous_raid_disks, pd_idx, 0);
3897                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3898                 set_bit(STRIPE_HANDLE, &sh->state);
3899                 release_stripe(sh);
3900                 first_sector += STRIPE_SECTORS;
3901         }
3902         return conf->chunk_size>>9;
3903 }
3904
3905 /* FIXME go_faster isn't used */
3906 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
3907 {
3908         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
3909         struct stripe_head *sh;
3910         int pd_idx;
3911         int raid_disks = conf->raid_disks;
3912         sector_t max_sector = mddev->size << 1;
3913         int sync_blocks;
3914         int still_degraded = 0;
3915         int i;
3916
3917         if (sector_nr >= max_sector) {
3918                 /* just being told to finish up .. nothing much to do */
3919                 unplug_slaves(mddev);
3920                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
3921                         end_reshape(conf);
3922                         return 0;
3923                 }
3924
3925                 if (mddev->curr_resync < max_sector) /* aborted */
3926                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
3927                                         &sync_blocks, 1);
3928                 else /* completed sync */
3929                         conf->fullsync = 0;
3930                 bitmap_close_sync(mddev->bitmap);
3931
3932                 return 0;
3933         }
3934
3935         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
3936                 return reshape_request(mddev, sector_nr, skipped);
3937
3938         /* if there is too many failed drives and we are trying
3939          * to resync, then assert that we are finished, because there is
3940          * nothing we can do.
3941          */
3942         if (mddev->degraded >= conf->max_degraded &&
3943             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
3944                 sector_t rv = (mddev->size << 1) - sector_nr;
3945                 *skipped = 1;
3946                 return rv;
3947         }
3948         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
3949             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
3950             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
3951                 /* we can skip this block, and probably more */
3952                 sync_blocks /= STRIPE_SECTORS;
3953                 *skipped = 1;
3954                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
3955         }
3956
3957         pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
3958         sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
3959         if (sh == NULL) {
3960                 sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
3961                 /* make sure we don't swamp the stripe cache if someone else
3962                  * is trying to get access
3963                  */
3964                 schedule_timeout_uninterruptible(1);
3965         }
3966         /* Need to check if array will still be degraded after recovery/resync
3967          * We don't need to check the 'failed' flag as when that gets set,
3968          * recovery aborts.
3969          */
3970         for (i=0; i<mddev->raid_disks; i++)
3971                 if (conf->disks[i].rdev == NULL)
3972                         still_degraded = 1;
3973
3974         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
3975
3976         spin_lock(&sh->lock);
3977         set_bit(STRIPE_SYNCING, &sh->state);
3978         clear_bit(STRIPE_INSYNC, &sh->state);
3979         spin_unlock(&sh->lock);
3980
3981         handle_stripe(sh, NULL);
3982         release_stripe(sh);
3983
3984         return STRIPE_SECTORS;
3985 }
3986
3987 static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
3988 {
3989         /* We may not be able to submit a whole bio at once as there
3990          * may not be enough stripe_heads available.
3991          * We cannot pre-allocate enough stripe_heads as we may need
3992          * more than exist in the cache (if we allow ever large chunks).
3993          * So we do one stripe head at a time and record in
3994          * ->bi_hw_segments how many have been done.
3995          *
3996          * We *know* that this entire raid_bio is in one chunk, so
3997          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
3998          */
3999         struct stripe_head *sh;
4000         int dd_idx, pd_idx;
4001         sector_t sector, logical_sector, last_sector;
4002         int scnt = 0;
4003         int remaining;
4004         int handled = 0;
4005
4006         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4007         sector = raid5_compute_sector(  logical_sector,
4008                                         conf->raid_disks,
4009                                         conf->raid_disks - conf->max_degraded,
4010                                         &dd_idx,
4011                                         &pd_idx,
4012                                         conf);
4013         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
4014
4015         for (; logical_sector < last_sector;
4016              logical_sector += STRIPE_SECTORS,
4017                      sector += STRIPE_SECTORS,
4018                      scnt++) {
4019
4020                 if (scnt < raid_bio->bi_hw_segments)
4021                         /* already done this stripe */
4022                         continue;
4023
4024                 sh = get_active_stripe(conf, sector, conf->raid_disks, pd_idx, 1);
4025
4026                 if (!sh) {
4027                         /* failed to get a stripe - must wait */
4028                         raid_bio->bi_hw_segments = scnt;
4029                         conf->retry_read_aligned = raid_bio;
4030                         return handled;
4031                 }
4032
4033                 set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
4034                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4035                         release_stripe(sh);
4036                         raid_bio->bi_hw_segments = scnt;
4037                         conf->retry_read_aligned = raid_bio;
4038                         return handled;
4039                 }
4040
4041                 handle_stripe(sh, NULL);
4042                 release_stripe(sh);
4043                 handled++;
4044         }
4045         spin_lock_irq(&conf->device_lock);
4046         remaining = --raid_bio->bi_phys_segments;
4047         spin_unlock_irq(&conf->device_lock);
4048         if (remaining == 0) {
4049                 int bytes = raid_bio->bi_size;
4050
4051                 raid_bio->bi_size = 0;
4052                 raid_bio->bi_end_io(raid_bio, bytes,
4053                               test_bit(BIO_UPTODATE, &raid_bio->bi_flags)
4054                                 ? 0 : -EIO);
4055         }
4056         if (atomic_dec_and_test(&conf->active_aligned_reads))
4057                 wake_up(&conf->wait_for_stripe);
4058         return handled;
4059 }
4060
4061
4062
4063 /*
4064  * This is our raid5 kernel thread.
4065  *
4066  * We scan the hash table for stripes which can be handled now.
4067  * During the scan, completed stripes are saved for us by the interrupt
4068  * handler, so that they will not have to wait for our next wakeup.
4069  */
4070 static void raid5d (mddev_t *mddev)
4071 {
4072         struct stripe_head *sh;
4073         raid5_conf_t *conf = mddev_to_conf(mddev);
4074         int handled;
4075
4076         pr_debug("+++ raid5d active\n");
4077
4078         md_check_recovery(mddev);
4079
4080         handled = 0;
4081         spin_lock_irq(&conf->device_lock);
4082         while (1) {
4083                 struct list_head *first;
4084                 struct bio *bio;
4085
4086                 if (conf->seq_flush != conf->seq_write) {
4087                         int seq = conf->seq_flush;
4088                         spin_unlock_irq(&conf->device_lock);
4089                         bitmap_unplug(mddev->bitmap);
4090                         spin_lock_irq(&conf->device_lock);
4091                         conf->seq_write = seq;
4092                         activate_bit_delay(conf);
4093                 }
4094
4095                 if (list_empty(&conf->handle_list) &&
4096                     atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
4097                     !blk_queue_plugged(mddev->queue) &&
4098                     !list_empty(&conf->delayed_list))
4099                         raid5_activate_delayed(conf);
4100
4101                 while ((bio = remove_bio_from_retry(conf))) {
4102                         int ok;
4103                         spin_unlock_irq(&conf->device_lock);
4104                         ok = retry_aligned_read(conf, bio);
4105                         spin_lock_irq(&conf->device_lock);
4106                         if (!ok)
4107                                 break;
4108                         handled++;
4109                 }
4110
4111                 if (list_empty(&conf->handle_list)) {
4112                         async_tx_issue_pending_all();
4113                         break;
4114                 }
4115
4116                 first = conf->handle_list.next;
4117                 sh = list_entry(first, struct stripe_head, lru);
4118
4119                 list_del_init(first);
4120                 atomic_inc(&sh->count);
4121                 BUG_ON(atomic_read(&sh->count)!= 1);
4122                 spin_unlock_irq(&conf->device_lock);
4123
4124                 handled++;
4125                 handle_stripe(sh, conf->spare_page);
4126                 release_stripe(sh);
4127
4128                 spin_lock_irq(&conf->device_lock);
4129         }
4130         pr_debug("%d stripes handled\n", handled);
4131
4132         spin_unlock_irq(&conf->device_lock);
4133
4134         unplug_slaves(mddev);
4135
4136         pr_debug("--- raid5d inactive\n");
4137 }
4138
4139 static ssize_t
4140 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
4141 {
4142         raid5_conf_t *conf = mddev_to_conf(mddev);
4143         if (conf)
4144                 return sprintf(page, "%d\n", conf->max_nr_stripes);
4145         else
4146                 return 0;
4147 }
4148
4149 static ssize_t
4150 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
4151 {
4152         raid5_conf_t *conf = mddev_to_conf(mddev);
4153         char *end;
4154         int new;
4155         if (len >= PAGE_SIZE)
4156                 return -EINVAL;
4157         if (!conf)
4158                 return -ENODEV;
4159
4160         new = simple_strtoul(page, &end, 10);
4161         if (!*page || (*end && *end != '\n') )
4162                 return -EINVAL;
4163         if (new <= 16 || new > 32768)
4164                 return -EINVAL;
4165         while (new < conf->max_nr_stripes) {
4166                 if (drop_one_stripe(conf))
4167                         conf->max_nr_stripes--;
4168                 else
4169                         break;
4170         }
4171         md_allow_write(mddev);
4172         while (new > conf->max_nr_stripes) {
4173                 if (grow_one_stripe(conf))
4174                         conf->max_nr_stripes++;
4175                 else break;
4176         }
4177         return len;
4178 }
4179
4180 static struct md_sysfs_entry
4181 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4182                                 raid5_show_stripe_cache_size,
4183                                 raid5_store_stripe_cache_size);
4184
4185 static ssize_t
4186 stripe_cache_active_show(mddev_t *mddev, char *page)
4187 {
4188         raid5_conf_t *conf = mddev_to_conf(mddev);
4189         if (conf)
4190                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
4191         else
4192                 return 0;
4193 }
4194
4195 static struct md_sysfs_entry
4196 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
4197
4198 static struct attribute *raid5_attrs[] =  {
4199         &raid5_stripecache_size.attr,
4200         &raid5_stripecache_active.attr,
4201         NULL,
4202 };
4203 static struct attribute_group raid5_attrs_group = {
4204         .name = NULL,
4205         .attrs = raid5_attrs,
4206 };
4207
4208 static int run(mddev_t *mddev)
4209 {
4210         raid5_conf_t *conf;
4211         int raid_disk, memory;
4212         mdk_rdev_t *rdev;
4213         struct disk_info *disk;
4214         struct list_head *tmp;
4215         int working_disks = 0;
4216
4217         if (mddev->level != 5 && mddev->level != 4 && mddev->level != 6) {
4218                 printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
4219                        mdname(mddev), mddev->level);
4220                 return -EIO;
4221         }
4222
4223         if (mddev->reshape_position != MaxSector) {
4224                 /* Check that we can continue the reshape.
4225                  * Currently only disks can change, it must
4226                  * increase, and we must be past the point where
4227                  * a stripe over-writes itself
4228                  */
4229                 sector_t here_new, here_old;
4230                 int old_disks;
4231                 int max_degraded = (mddev->level == 5 ? 1 : 2);
4232
4233                 if (mddev->new_level != mddev->level ||
4234                     mddev->new_layout != mddev->layout ||
4235                     mddev->new_chunk != mddev->chunk_size) {
4236                         printk(KERN_ERR "raid5: %s: unsupported reshape "
4237                                "required - aborting.\n",
4238                                mdname(mddev));
4239                         return -EINVAL;
4240                 }
4241                 if (mddev->delta_disks <= 0) {
4242                         printk(KERN_ERR "raid5: %s: unsupported reshape "
4243                                "(reduce disks) required - aborting.\n",
4244                                mdname(mddev));
4245                         return -EINVAL;
4246                 }
4247                 old_disks = mddev->raid_disks - mddev->delta_disks;
4248                 /* reshape_position must be on a new-stripe boundary, and one
4249                  * further up in new geometry must map after here in old
4250                  * geometry.
4251                  */
4252                 here_new = mddev->reshape_position;
4253                 if (sector_div(here_new, (mddev->chunk_size>>9)*
4254                                (mddev->raid_disks - max_degraded))) {
4255                         printk(KERN_ERR "raid5: reshape_position not "
4256                                "on a stripe boundary\n");
4257                         return -EINVAL;
4258                 }
4259                 /* here_new is the stripe we will write to */
4260                 here_old = mddev->reshape_position;
4261                 sector_div(here_old, (mddev->chunk_size>>9)*
4262                            (old_disks-max_degraded));
4263                 /* here_old is the first stripe that we might need to read
4264                  * from */
4265                 if (here_new >= here_old) {
4266                         /* Reading from the same stripe as writing to - bad */
4267                         printk(KERN_ERR "raid5: reshape_position too early for "
4268                                "auto-recovery - aborting.\n");
4269                         return -EINVAL;
4270                 }
4271                 printk(KERN_INFO "raid5: reshape will continue\n");
4272                 /* OK, we should be able to continue; */
4273         }
4274
4275
4276         mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
4277         if ((conf = mddev->private) == NULL)
4278                 goto abort;
4279         if (mddev->reshape_position == MaxSector) {
4280                 conf->previous_raid_disks = conf->raid_disks = mddev->raid_disks;
4281         } else {
4282                 conf->raid_disks = mddev->raid_disks;
4283                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
4284         }
4285
4286         conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
4287                               GFP_KERNEL);
4288         if (!conf->disks)
4289                 goto abort;
4290
4291         conf->mddev = mddev;
4292
4293         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
4294                 goto abort;
4295
4296         if (mddev->level == 6) {
4297                 conf->spare_page = alloc_page(GFP_KERNEL);
4298                 if (!conf->spare_page)
4299                         goto abort;
4300         }
4301         spin_lock_init(&conf->device_lock);
4302         init_waitqueue_head(&conf->wait_for_stripe);
4303         init_waitqueue_head(&conf->wait_for_overlap);
4304         INIT_LIST_HEAD(&conf->handle_list);
4305         INIT_LIST_HEAD(&conf->delayed_list);
4306         INIT_LIST_HEAD(&conf->bitmap_list);
4307         INIT_LIST_HEAD(&conf->inactive_list);
4308         atomic_set(&conf->active_stripes, 0);
4309         atomic_set(&conf->preread_active_stripes, 0);
4310         atomic_set(&conf->active_aligned_reads, 0);
4311
4312         pr_debug("raid5: run(%s) called.\n", mdname(mddev));
4313
4314         ITERATE_RDEV(mddev,rdev,tmp) {
4315                 raid_disk = rdev->raid_disk;
4316                 if (raid_disk >= conf->raid_disks
4317                     || raid_disk < 0)
4318                         continue;
4319                 disk = conf->disks + raid_disk;
4320
4321                 disk->rdev = rdev;
4322
4323                 if (test_bit(In_sync, &rdev->flags)) {
4324                         char b[BDEVNAME_SIZE];
4325                         printk(KERN_INFO "raid5: device %s operational as raid"
4326                                 " disk %d\n", bdevname(rdev->bdev,b),
4327                                 raid_disk);
4328                         working_disks++;
4329                 }
4330         }
4331
4332         /*
4333          * 0 for a fully functional array, 1 or 2 for a degraded array.
4334          */
4335         mddev->degraded = conf->raid_disks - working_disks;
4336         conf->mddev = mddev;
4337         conf->chunk_size = mddev->chunk_size;
4338         conf->level = mddev->level;
4339         if (conf->level == 6)
4340                 conf->max_degraded = 2;
4341         else
4342                 conf->max_degraded = 1;
4343         conf->algorithm = mddev->layout;
4344         conf->max_nr_stripes = NR_STRIPES;
4345         conf->expand_progress = mddev->reshape_position;
4346
4347         /* device size must be a multiple of chunk size */
4348         mddev->size &= ~(mddev->chunk_size/1024 -1);
4349         mddev->resync_max_sectors = mddev->size << 1;
4350
4351         if (conf->level == 6 && conf->raid_disks < 4) {
4352                 printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
4353                        mdname(mddev), conf->raid_disks);
4354                 goto abort;
4355         }
4356         if (!conf->chunk_size || conf->chunk_size % 4) {
4357                 printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
4358                         conf->chunk_size, mdname(mddev));
4359                 goto abort;
4360         }
4361         if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
4362                 printk(KERN_ERR
4363                         "raid5: unsupported parity algorithm %d for %s\n",
4364                         conf->algorithm, mdname(mddev));
4365                 goto abort;
4366         }
4367         if (mddev->degraded > conf->max_degraded) {
4368                 printk(KERN_ERR "raid5: not enough operational devices for %s"
4369                         " (%d/%d failed)\n",
4370                         mdname(mddev), mddev->degraded, conf->raid_disks);
4371                 goto abort;
4372         }
4373
4374         if (mddev->degraded > 0 &&
4375             mddev->recovery_cp != MaxSector) {
4376                 if (mddev->ok_start_degraded)
4377                         printk(KERN_WARNING
4378                                "raid5: starting dirty degraded array: %s"
4379                                "- data corruption possible.\n",
4380                                mdname(mddev));
4381                 else {
4382                         printk(KERN_ERR
4383                                "raid5: cannot start dirty degraded array for %s\n",
4384                                mdname(mddev));
4385                         goto abort;
4386                 }
4387         }
4388
4389         {
4390                 mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5");
4391                 if (!mddev->thread) {
4392                         printk(KERN_ERR
4393                                 "raid5: couldn't allocate thread for %s\n",
4394                                 mdname(mddev));
4395                         goto abort;
4396                 }
4397         }
4398         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
4399                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
4400         if (grow_stripes(conf, conf->max_nr_stripes)) {
4401                 printk(KERN_ERR
4402                         "raid5: couldn't allocate %dkB for buffers\n", memory);
4403                 shrink_stripes(conf);
4404                 md_unregister_thread(mddev->thread);
4405                 goto abort;
4406         } else
4407                 printk(KERN_INFO "raid5: allocated %dkB for %s\n",
4408                         memory, mdname(mddev));
4409
4410         if (mddev->degraded == 0)
4411                 printk("raid5: raid level %d set %s active with %d out of %d"
4412                         " devices, algorithm %d\n", conf->level, mdname(mddev),
4413                         mddev->raid_disks-mddev->degraded, mddev->raid_disks,
4414                         conf->algorithm);
4415         else
4416                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
4417                         " out of %d devices, algorithm %d\n", conf->level,
4418                         mdname(mddev), mddev->raid_disks - mddev->degraded,
4419                         mddev->raid_disks, conf->algorithm);
4420
4421         print_raid5_conf(conf);
4422
4423         if (conf->expand_progress != MaxSector) {
4424                 printk("...ok start reshape thread\n");
4425                 conf->expand_lo = conf->expand_progress;
4426                 atomic_set(&conf->reshape_stripes, 0);
4427                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4428                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4429                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4430                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4431                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4432                                                         "%s_reshape");
4433         }
4434
4435         /* read-ahead size must cover two whole stripes, which is
4436          * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4437          */
4438         {
4439                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
4440                 int stripe = data_disks *
4441                         (mddev->chunk_size / PAGE_SIZE);
4442                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4443                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4444         }
4445
4446         /* Ok, everything is just fine now */
4447         if (sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
4448                 printk(KERN_WARNING
4449                        "raid5: failed to create sysfs attributes for %s\n",
4450                        mdname(mddev));
4451
4452         mddev->queue->unplug_fn = raid5_unplug_device;
4453         mddev->queue->issue_flush_fn = raid5_issue_flush;
4454         mddev->queue->backing_dev_info.congested_data = mddev;
4455         mddev->queue->backing_dev_info.congested_fn = raid5_congested;
4456
4457         mddev->array_size =  mddev->size * (conf->previous_raid_disks -
4458                                             conf->max_degraded);
4459
4460         blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
4461
4462         return 0;
4463 abort:
4464         if (conf) {
4465                 print_raid5_conf(conf);
4466                 safe_put_page(conf->spare_page);
4467                 kfree(conf->disks);
4468                 kfree(conf->stripe_hashtbl);
4469                 kfree(conf);
4470         }
4471         mddev->private = NULL;
4472         printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
4473         return -EIO;
4474 }
4475
4476
4477
4478 static int stop(mddev_t *mddev)
4479 {
4480         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4481
4482         md_unregister_thread(mddev->thread);
4483         mddev->thread = NULL;
4484         shrink_stripes(conf);
4485         kfree(conf->stripe_hashtbl);
4486         mddev->queue->backing_dev_info.congested_fn = NULL;
4487         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
4488         sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
4489         kfree(conf->disks);
4490         kfree(conf);
4491         mddev->private = NULL;
4492         return 0;
4493 }
4494
4495 #ifdef DEBUG
4496 static void print_sh (struct seq_file *seq, struct stripe_head *sh)
4497 {
4498         int i;
4499
4500         seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
4501                    (unsigned long long)sh->sector, sh->pd_idx, sh->state);
4502         seq_printf(seq, "sh %llu,  count %d.\n",
4503                    (unsigned long long)sh->sector, atomic_read(&sh->count));
4504         seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
4505         for (i = 0; i < sh->disks; i++) {
4506                 seq_printf(seq, "(cache%d: %p %ld) ",
4507                            i, sh->dev[i].page, sh->dev[i].flags);
4508         }
4509         seq_printf(seq, "\n");
4510 }
4511
4512 static void printall (struct seq_file *seq, raid5_conf_t *conf)
4513 {
4514         struct stripe_head *sh;
4515         struct hlist_node *hn;
4516         int i;
4517
4518         spin_lock_irq(&conf->device_lock);
4519         for (i = 0; i < NR_HASH; i++) {
4520                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
4521                         if (sh->raid_conf != conf)
4522                                 continue;
4523                         print_sh(seq, sh);
4524                 }
4525         }
4526         spin_unlock_irq(&conf->device_lock);
4527 }
4528 #endif
4529
4530 static void status (struct seq_file *seq, mddev_t *mddev)
4531 {
4532         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
4533         int i;
4534
4535         seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout);
4536         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
4537         for (i = 0; i < conf->raid_disks; i++)
4538                 seq_printf (seq, "%s",
4539                                conf->disks[i].rdev &&
4540                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
4541         seq_printf (seq, "]");
4542 #ifdef DEBUG
4543         seq_printf (seq, "\n");
4544         printall(seq, conf);
4545 #endif
4546 }
4547
4548 static void print_raid5_conf (raid5_conf_t *conf)
4549 {
4550         int i;
4551         struct disk_info *tmp;
4552
4553         printk("RAID5 conf printout:\n");
4554         if (!conf) {
4555                 printk("(conf==NULL)\n");
4556                 return;
4557         }
4558         printk(" --- rd:%d wd:%d\n", conf->raid_disks,
4559                  conf->raid_disks - conf->mddev->degraded);
4560
4561         for (i = 0; i < conf->raid_disks; i++) {
4562                 char b[BDEVNAME_SIZE];
4563                 tmp = conf->disks + i;
4564                 if (tmp->rdev)
4565                 printk(" disk %d, o:%d, dev:%s\n",
4566                         i, !test_bit(Faulty, &tmp->rdev->flags),
4567                         bdevname(tmp->rdev->bdev,b));
4568         }
4569 }
4570
4571 static int raid5_spare_active(mddev_t *mddev)
4572 {
4573         int i;
4574         raid5_conf_t *conf = mddev->private;
4575         struct disk_info *tmp;
4576
4577         for (i = 0; i < conf->raid_disks; i++) {
4578                 tmp = conf->disks + i;
4579                 if (tmp->rdev
4580                     && !test_bit(Faulty, &tmp->rdev->flags)
4581                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
4582                         unsigned long flags;
4583                         spin_lock_irqsave(&conf->device_lock, flags);
4584                         mddev->degraded--;
4585                         spin_unlock_irqrestore(&conf->device_lock, flags);
4586                 }
4587         }
4588         print_raid5_conf(conf);
4589         return 0;
4590 }
4591
4592 static int raid5_remove_disk(mddev_t *mddev, int number)
4593 {
4594         raid5_conf_t *conf = mddev->private;
4595         int err = 0;
4596         mdk_rdev_t *rdev;
4597         struct disk_info *p = conf->disks + number;
4598
4599         print_raid5_conf(conf);
4600         rdev = p->rdev;
4601         if (rdev) {
4602                 if (test_bit(In_sync, &rdev->flags) ||
4603                     atomic_read(&rdev->nr_pending)) {
4604                         err = -EBUSY;
4605                         goto abort;
4606                 }
4607                 p->rdev = NULL;
4608                 synchronize_rcu();
4609                 if (atomic_read(&rdev->nr_pending)) {
4610                         /* lost the race, try later */
4611                         err = -EBUSY;
4612                         p->rdev = rdev;
4613                 }
4614         }
4615 abort:
4616
4617         print_raid5_conf(conf);
4618         return err;
4619 }
4620
4621 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
4622 {
4623         raid5_conf_t *conf = mddev->private;
4624         int found = 0;
4625         int disk;
4626         struct disk_info *p;
4627
4628         if (mddev->degraded > conf->max_degraded)
4629                 /* no point adding a device */
4630                 return 0;
4631
4632         /*
4633          * find the disk ... but prefer rdev->saved_raid_disk
4634          * if possible.
4635          */
4636         if (rdev->saved_raid_disk >= 0 &&
4637             conf->disks[rdev->saved_raid_disk].rdev == NULL)
4638                 disk = rdev->saved_raid_disk;
4639         else
4640                 disk = 0;
4641         for ( ; disk < conf->raid_disks; disk++)
4642                 if ((p=conf->disks + disk)->rdev == NULL) {
4643                         clear_bit(In_sync, &rdev->flags);
4644                         rdev->raid_disk = disk;
4645                         found = 1;
4646                         if (rdev->saved_raid_disk != disk)
4647                                 conf->fullsync = 1;
4648                         rcu_assign_pointer(p->rdev, rdev);
4649                         break;
4650                 }
4651         print_raid5_conf(conf);
4652         return found;
4653 }
4654
4655 static int raid5_resize(mddev_t *mddev, sector_t sectors)
4656 {
4657         /* no resync is happening, and there is enough space
4658          * on all devices, so we can resize.
4659          * We need to make sure resync covers any new space.
4660          * If the array is shrinking we should possibly wait until
4661          * any io in the removed space completes, but it hardly seems
4662          * worth it.
4663          */
4664         raid5_conf_t *conf = mddev_to_conf(mddev);
4665
4666         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
4667         mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
4668         set_capacity(mddev->gendisk, mddev->array_size << 1);
4669         mddev->changed = 1;
4670         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
4671                 mddev->recovery_cp = mddev->size << 1;
4672                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
4673         }
4674         mddev->size = sectors /2;
4675         mddev->resync_max_sectors = sectors;
4676         return 0;
4677 }
4678
4679 #ifdef CONFIG_MD_RAID5_RESHAPE
4680 static int raid5_check_reshape(mddev_t *mddev)
4681 {
4682         raid5_conf_t *conf = mddev_to_conf(mddev);
4683         int err;
4684
4685         if (mddev->delta_disks < 0 ||
4686             mddev->new_level != mddev->level)
4687                 return -EINVAL; /* Cannot shrink array or change level yet */
4688         if (mddev->delta_disks == 0)
4689                 return 0; /* nothing to do */
4690
4691         /* Can only proceed if there are plenty of stripe_heads.
4692          * We need a minimum of one full stripe,, and for sensible progress
4693          * it is best to have about 4 times that.
4694          * If we require 4 times, then the default 256 4K stripe_heads will
4695          * allow for chunk sizes up to 256K, which is probably OK.
4696          * If the chunk size is greater, user-space should request more
4697          * stripe_heads first.
4698          */
4699         if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
4700             (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
4701                 printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
4702                        (mddev->chunk_size / STRIPE_SIZE)*4);
4703                 return -ENOSPC;
4704         }
4705
4706         err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
4707         if (err)
4708                 return err;
4709
4710         if (mddev->degraded > conf->max_degraded)
4711                 return -EINVAL;
4712         /* looks like we might be able to manage this */
4713         return 0;
4714 }
4715
4716 static int raid5_start_reshape(mddev_t *mddev)
4717 {
4718         raid5_conf_t *conf = mddev_to_conf(mddev);
4719         mdk_rdev_t *rdev;
4720         struct list_head *rtmp;
4721         int spares = 0;
4722         int added_devices = 0;
4723         unsigned long flags;
4724
4725         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
4726                 return -EBUSY;
4727
4728         ITERATE_RDEV(mddev, rdev, rtmp)
4729                 if (rdev->raid_disk < 0 &&
4730                     !test_bit(Faulty, &rdev->flags))
4731                         spares++;
4732
4733         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
4734                 /* Not enough devices even to make a degraded array
4735                  * of that size
4736                  */
4737                 return -EINVAL;
4738
4739         atomic_set(&conf->reshape_stripes, 0);
4740         spin_lock_irq(&conf->device_lock);
4741         conf->previous_raid_disks = conf->raid_disks;
4742         conf->raid_disks += mddev->delta_disks;
4743         conf->expand_progress = 0;
4744         conf->expand_lo = 0;
4745         spin_unlock_irq(&conf->device_lock);
4746
4747         /* Add some new drives, as many as will fit.
4748          * We know there are enough to make the newly sized array work.
4749          */
4750         ITERATE_RDEV(mddev, rdev, rtmp)
4751                 if (rdev->raid_disk < 0 &&
4752                     !test_bit(Faulty, &rdev->flags)) {
4753                         if (raid5_add_disk(mddev, rdev)) {
4754                                 char nm[20];
4755                                 set_bit(In_sync, &rdev->flags);
4756                                 added_devices++;
4757                                 rdev->recovery_offset = 0;
4758                                 sprintf(nm, "rd%d", rdev->raid_disk);
4759                                 if (sysfs_create_link(&mddev->kobj,
4760                                                       &rdev->kobj, nm))
4761                                         printk(KERN_WARNING
4762                                                "raid5: failed to create "
4763                                                " link %s for %s\n",
4764                                                nm, mdname(mddev));
4765                         } else
4766                                 break;
4767                 }
4768
4769         spin_lock_irqsave(&conf->device_lock, flags);
4770         mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
4771         spin_unlock_irqrestore(&conf->device_lock, flags);
4772         mddev->raid_disks = conf->raid_disks;
4773         mddev->reshape_position = 0;
4774         set_bit(MD_CHANGE_DEVS, &mddev->flags);
4775
4776         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
4777         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
4778         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
4779         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
4780         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
4781                                                 "%s_reshape");
4782         if (!mddev->sync_thread) {
4783                 mddev->recovery = 0;
4784                 spin_lock_irq(&conf->device_lock);
4785                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
4786                 conf->expand_progress = MaxSector;
4787                 spin_unlock_irq(&conf->device_lock);
4788                 return -EAGAIN;
4789         }
4790         md_wakeup_thread(mddev->sync_thread);
4791         md_new_event(mddev);
4792         return 0;
4793 }
4794 #endif
4795
4796 static void end_reshape(raid5_conf_t *conf)
4797 {
4798         struct block_device *bdev;
4799
4800         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
4801                 conf->mddev->array_size = conf->mddev->size *
4802                         (conf->raid_disks - conf->max_degraded);
4803                 set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
4804                 conf->mddev->changed = 1;
4805
4806                 bdev = bdget_disk(conf->mddev->gendisk, 0);
4807                 if (bdev) {
4808                         mutex_lock(&bdev->bd_inode->i_mutex);
4809                         i_size_write(bdev->bd_inode, (loff_t)conf->mddev->array_size << 10);
4810                         mutex_unlock(&bdev->bd_inode->i_mutex);
4811                         bdput(bdev);
4812                 }
4813                 spin_lock_irq(&conf->device_lock);
4814                 conf->expand_progress = MaxSector;
4815                 spin_unlock_irq(&conf->device_lock);
4816                 conf->mddev->reshape_position = MaxSector;
4817
4818                 /* read-ahead size must cover two whole stripes, which is
4819                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
4820                  */
4821                 {
4822                         int data_disks = conf->previous_raid_disks - conf->max_degraded;
4823                         int stripe = data_disks *
4824                                 (conf->mddev->chunk_size / PAGE_SIZE);
4825                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
4826                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
4827                 }
4828         }
4829 }
4830
4831 static void raid5_quiesce(mddev_t *mddev, int state)
4832 {
4833         raid5_conf_t *conf = mddev_to_conf(mddev);
4834
4835         switch(state) {
4836         case 2: /* resume for a suspend */
4837                 wake_up(&conf->wait_for_overlap);
4838                 break;
4839
4840         case 1: /* stop all writes */
4841                 spin_lock_irq(&conf->device_lock);
4842                 conf->quiesce = 1;
4843                 wait_event_lock_irq(conf->wait_for_stripe,
4844                                     atomic_read(&conf->active_stripes) == 0 &&
4845                                     atomic_read(&conf->active_aligned_reads) == 0,
4846                                     conf->device_lock, /* nothing */);
4847                 spin_unlock_irq(&conf->device_lock);
4848                 break;
4849
4850         case 0: /* re-enable writes */
4851                 spin_lock_irq(&conf->device_lock);
4852                 conf->quiesce = 0;
4853                 wake_up(&conf->wait_for_stripe);
4854                 wake_up(&conf->wait_for_overlap);
4855                 spin_unlock_irq(&conf->device_lock);
4856                 break;
4857         }
4858 }
4859
4860 static struct mdk_personality raid6_personality =
4861 {
4862         .name           = "raid6",
4863         .level          = 6,
4864         .owner          = THIS_MODULE,
4865         .make_request   = make_request,
4866         .run            = run,
4867         .stop           = stop,
4868         .status         = status,
4869         .error_handler  = error,
4870         .hot_add_disk   = raid5_add_disk,
4871         .hot_remove_disk= raid5_remove_disk,
4872         .spare_active   = raid5_spare_active,
4873         .sync_request   = sync_request,
4874         .resize         = raid5_resize,
4875 #ifdef CONFIG_MD_RAID5_RESHAPE
4876         .check_reshape  = raid5_check_reshape,
4877         .start_reshape  = raid5_start_reshape,
4878 #endif
4879         .quiesce        = raid5_quiesce,
4880 };
4881 static struct mdk_personality raid5_personality =
4882 {
4883         .name           = "raid5",
4884         .level          = 5,
4885         .owner          = THIS_MODULE,
4886         .make_request   = make_request,
4887         .run            = run,
4888         .stop           = stop,
4889         .status         = status,
4890         .error_handler  = error,
4891         .hot_add_disk   = raid5_add_disk,
4892         .hot_remove_disk= raid5_remove_disk,
4893         .spare_active   = raid5_spare_active,
4894         .sync_request   = sync_request,
4895         .resize         = raid5_resize,
4896 #ifdef CONFIG_MD_RAID5_RESHAPE
4897         .check_reshape  = raid5_check_reshape,
4898         .start_reshape  = raid5_start_reshape,
4899 #endif
4900         .quiesce        = raid5_quiesce,
4901 };
4902
4903 static struct mdk_personality raid4_personality =
4904 {
4905         .name           = "raid4",
4906         .level          = 4,
4907         .owner          = THIS_MODULE,
4908         .make_request   = make_request,
4909         .run            = run,
4910         .stop           = stop,
4911         .status         = status,
4912         .error_handler  = error,
4913         .hot_add_disk   = raid5_add_disk,
4914         .hot_remove_disk= raid5_remove_disk,
4915         .spare_active   = raid5_spare_active,
4916         .sync_request   = sync_request,
4917         .resize         = raid5_resize,
4918 #ifdef CONFIG_MD_RAID5_RESHAPE
4919         .check_reshape  = raid5_check_reshape,
4920         .start_reshape  = raid5_start_reshape,
4921 #endif
4922         .quiesce        = raid5_quiesce,
4923 };
4924
4925 static int __init raid5_init(void)
4926 {
4927         int e;
4928
4929         e = raid6_select_algo();
4930         if ( e )
4931                 return e;
4932         register_md_personality(&raid6_personality);
4933         register_md_personality(&raid5_personality);
4934         register_md_personality(&raid4_personality);
4935         return 0;
4936 }
4937
4938 static void raid5_exit(void)
4939 {
4940         unregister_md_personality(&raid6_personality);
4941         unregister_md_personality(&raid5_personality);
4942         unregister_md_personality(&raid4_personality);
4943 }
4944
4945 module_init(raid5_init);
4946 module_exit(raid5_exit);
4947 MODULE_LICENSE("GPL");
4948 MODULE_ALIAS("md-personality-4"); /* RAID5 */
4949 MODULE_ALIAS("md-raid5");
4950 MODULE_ALIAS("md-raid4");
4951 MODULE_ALIAS("md-level-5");
4952 MODULE_ALIAS("md-level-4");
4953 MODULE_ALIAS("md-personality-8"); /* RAID6 */
4954 MODULE_ALIAS("md-raid6");
4955 MODULE_ALIAS("md-level-6");
4956
4957 /* This used to be two separate modules, they were: */
4958 MODULE_ALIAS("raid5");
4959 MODULE_ALIAS("raid6");