fs/btrfs/extent_io.c

   1 #include <linux/bitops.h>
   2 #include <linux/slab.h>
   3 #include <linux/bio.h>
   4 #include <linux/mm.h>
   5 #include <linux/pagemap.h>
   6 #include <linux/page-flags.h>
   7 #include <linux/module.h>
   8 #include <linux/spinlock.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/swap.h>
  11 #include <linux/writeback.h>
  12 #include <linux/pagevec.h>
  13 #include <linux/prefetch.h>
  14 #include <linux/cleancache.h>
  15 #include "extent_io.h"
  16 #include "extent_map.h"
  17 #include "compat.h"
  18 #include "ctree.h"
  19 #include "btrfs_inode.h"
  20 #include "volumes.h"
  21 #include "check-integrity.h"
  22
  23 static struct kmem_cache *extent_state_cache;
  24 static struct kmem_cache *extent_buffer_cache;
  25
  26 static LIST_HEAD(buffers);
  27 static LIST_HEAD(states);
  28
  29 #define LEAK_DEBUG 0
  30 #if LEAK_DEBUG
  31 static DEFINE_SPINLOCK(leak_lock);
  32 #endif
  33
  34 #define BUFFER_LRU_MAX 64
  35
  36 struct tree_entry {
  37         u64 start;
  38         u64 end;
  39         struct rb_node rb_node;
  40 };
  41
  42 struct extent_page_data {
  43         struct bio *bio;
  44         struct extent_io_tree *tree;
  45         get_extent_t *get_extent;
  46
  47         /* tells writepage not to lock the state bits for this range
  48          * it still does the unlocking
  49          */
  50         unsigned int extent_locked:1;
  51
  52         /* tells the submit_bio code to use a WRITE_SYNC */
  53         unsigned int sync_io:1;
  54 };
  55
  56 int __init extent_io_init(void)
  57 {
  58         extent_state_cache = kmem_cache_create("extent_state",
  59                         sizeof(struct extent_state), 0,
  60                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
  61         if (!extent_state_cache)
  62                 return -ENOMEM;
  63
  64         extent_buffer_cache = kmem_cache_create("extent_buffers",
  65                         sizeof(struct extent_buffer), 0,
  66                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
  67         if (!extent_buffer_cache)
  68                 goto free_state_cache;
  69         return 0;
  70
  71 free_state_cache:
  72         kmem_cache_destroy(extent_state_cache);
  73         return -ENOMEM;
  74 }
  75
  76 void extent_io_exit(void)
  77 {
  78         struct extent_state *state;
  79         struct extent_buffer *eb;
  80
  81         while (!list_empty(&states)) {
  82                 state = list_entry(states.next, struct extent_state, leak_list);
  83                 printk(KERN_ERR "btrfs state leak: start %llu end %llu "
  84                        "state %lu in tree %p refs %d\n",
  85                        (unsigned long long)state->start,
  86                        (unsigned long long)state->end,
  87                        state->state, state->tree, atomic_read(&state->refs));
  88                 list_del(&state->leak_list);
  89                 kmem_cache_free(extent_state_cache, state);
  90
  91         }
  92
  93         while (!list_empty(&buffers)) {
  94                 eb = list_entry(buffers.next, struct extent_buffer, leak_list);
  95                 printk(KERN_ERR "btrfs buffer leak start %llu len %lu "
  96                        "refs %d\n", (unsigned long long)eb->start,
  97                        eb->len, atomic_read(&eb->refs));
  98                 list_del(&eb->leak_list);
  99                 kmem_cache_free(extent_buffer_cache, eb);
 100         }
 101         if (extent_state_cache)
 102                 kmem_cache_destroy(extent_state_cache);
 103         if (extent_buffer_cache)
 104                 kmem_cache_destroy(extent_buffer_cache);
 105 }
 106
 107 void extent_io_tree_init(struct extent_io_tree *tree,
 108                          struct address_space *mapping)
 109 {
 110         tree->state = RB_ROOT;
 111         INIT_RADIX_TREE(&tree->buffer, GFP_ATOMIC);
 112         tree->ops = NULL;
 113         tree->dirty_bytes = 0;
 114         spin_lock_init(&tree->lock);
 115         spin_lock_init(&tree->buffer_lock);
 116         tree->mapping = mapping;
 117 }
 118
 119 static struct extent_state *alloc_extent_state(gfp_t mask)
 120 {
 121         struct extent_state *state;
 122 #if LEAK_DEBUG
 123         unsigned long flags;
 124 #endif
 125
 126         state = kmem_cache_alloc(extent_state_cache, mask);
 127         if (!state)
 128                 return state;
 129         state->state = 0;
 130         state->private = 0;
 131         state->tree = NULL;
 132 #if LEAK_DEBUG
 133         spin_lock_irqsave(&leak_lock, flags);
 134         list_add(&state->leak_list, &states);
 135         spin_unlock_irqrestore(&leak_lock, flags);
 136 #endif
 137         atomic_set(&state->refs, 1);
 138         init_waitqueue_head(&state->wq);
 139         return state;
 140 }
 141
 142 void free_extent_state(struct extent_state *state)
 143 {
 144         if (!state)
 145                 return;
 146         if (atomic_dec_and_test(&state->refs)) {
 147 #if LEAK_DEBUG
 148                 unsigned long flags;
 149 #endif
 150                 WARN_ON(state->tree);
 151 #if LEAK_DEBUG
 152                 spin_lock_irqsave(&leak_lock, flags);
 153                 list_del(&state->leak_list);
 154                 spin_unlock_irqrestore(&leak_lock, flags);
 155 #endif
 156                 kmem_cache_free(extent_state_cache, state);
 157         }
 158 }
 159
 160 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
 161                                    struct rb_node *node)
 162 {
 163         struct rb_node **p = &root->rb_node;
 164         struct rb_node *parent = NULL;
 165         struct tree_entry *entry;
 166
 167         while (*p) {
 168                 parent = *p;
 169                 entry = rb_entry(parent, struct tree_entry, rb_node);
 170
 171                 if (offset < entry->start)
 172                         p = &(*p)->rb_left;
 173                 else if (offset > entry->end)
 174                         p = &(*p)->rb_right;
 175                 else
 176                         return parent;
 177         }
 178
 179         entry = rb_entry(node, struct tree_entry, rb_node);
 180         rb_link_node(node, parent, p);
 181         rb_insert_color(node, root);
 182         return NULL;
 183 }
 184
 185 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 186                                      struct rb_node **prev_ret,
 187                                      struct rb_node **next_ret)
 188 {
 189         struct rb_root *root = &tree->state;
 190         struct rb_node *n = root->rb_node;
 191         struct rb_node *prev = NULL;
 192         struct rb_node *orig_prev = NULL;
 193         struct tree_entry *entry;
 194         struct tree_entry *prev_entry = NULL;
 195
 196         while (n) {
 197                 entry = rb_entry(n, struct tree_entry, rb_node);
 198                 prev = n;
 199                 prev_entry = entry;
 200
 201                 if (offset < entry->start)
 202                         n = n->rb_left;
 203                 else if (offset > entry->end)
 204                         n = n->rb_right;
 205                 else
 206                         return n;
 207         }
 208
 209         if (prev_ret) {
 210                 orig_prev = prev;
 211                 while (prev && offset > prev_entry->end) {
 212                         prev = rb_next(prev);
 213                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 214                 }
 215                 *prev_ret = prev;
 216                 prev = orig_prev;
 217         }
 218
 219         if (next_ret) {
 220                 prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 221                 while (prev && offset < prev_entry->start) {
 222                         prev = rb_prev(prev);
 223                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 224                 }
 225                 *next_ret = prev;
 226         }
 227         return NULL;
 228 }
 229
 230 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
 231                                           u64 offset)
 232 {
 233         struct rb_node *prev = NULL;
 234         struct rb_node *ret;
 235
 236         ret = __etree_search(tree, offset, &prev, NULL);
 237         if (!ret)
 238                 return prev;
 239         return ret;
 240 }
 241
 242 static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
 243                      struct extent_state *other)
 244 {
 245         if (tree->ops && tree->ops->merge_extent_hook)
 246                 tree->ops->merge_extent_hook(tree->mapping->host, new,
 247                                              other);
 248 }
 249
 250 /*
 251  * utility function to look for merge candidates inside a given range.
 252  * Any extents with matching state are merged together into a single
 253  * extent in the tree.  Extents with EXTENT_IO in their state field
 254  * are not merged because the end_io handlers need to be able to do
 255  * operations on them without sleeping (or doing allocations/splits).
 256  *
 257  * This should be called with the tree lock held.
 258  */
 259 static void merge_state(struct extent_io_tree *tree,
 260                         struct extent_state *state)
 261 {
 262         struct extent_state *other;
 263         struct rb_node *other_node;
 264
 265         if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 266                 return;
 267
 268         other_node = rb_prev(&state->rb_node);
 269         if (other_node) {
 270                 other = rb_entry(other_node, struct extent_state, rb_node);
 271                 if (other->end == state->start - 1 &&
 272                     other->state == state->state) {
 273                         merge_cb(tree, state, other);
 274                         state->start = other->start;
 275                         other->tree = NULL;
 276                         rb_erase(&other->rb_node, &tree->state);
 277                         free_extent_state(other);
 278                 }
 279         }
 280         other_node = rb_next(&state->rb_node);
 281         if (other_node) {
 282                 other = rb_entry(other_node, struct extent_state, rb_node);
 283                 if (other->start == state->end + 1 &&
 284                     other->state == state->state) {
 285                         merge_cb(tree, state, other);
 286                         state->end = other->end;
 287                         other->tree = NULL;
 288                         rb_erase(&other->rb_node, &tree->state);
 289                         free_extent_state(other);
 290                 }
 291         }
 292 }
 293
 294 static void set_state_cb(struct extent_io_tree *tree,
 295                          struct extent_state *state, int *bits)
 296 {
 297         if (tree->ops && tree->ops->set_bit_hook)
 298                 tree->ops->set_bit_hook(tree->mapping->host, state, bits);
 299 }
 300
 301 static void clear_state_cb(struct extent_io_tree *tree,
 302                            struct extent_state *state, int *bits)
 303 {
 304         if (tree->ops && tree->ops->clear_bit_hook)
 305                 tree->ops->clear_bit_hook(tree->mapping->host, state, bits);
 306 }
 307
 308 static void set_state_bits(struct extent_io_tree *tree,
 309                            struct extent_state *state, int *bits);
 310
 311 /*
 312  * insert an extent_state struct into the tree.  'bits' are set on the
 313  * struct before it is inserted.
 314  *
 315  * This may return -EEXIST if the extent is already there, in which case the
 316  * state struct is freed.
 317  *
 318  * The tree lock is not taken internally.  This is a utility function and
 319  * probably isn't what you want to call (see set/clear_extent_bit).
 320  */
 321 static int insert_state(struct extent_io_tree *tree,
 322                         struct extent_state *state, u64 start, u64 end,
 323                         int *bits)
 324 {
 325         struct rb_node *node;
 326
 327         if (end < start) {
 328                 printk(KERN_ERR "btrfs end < start %llu %llu\n",
 329                        (unsigned long long)end,
 330                        (unsigned long long)start);
 331                 WARN_ON(1);
 332         }
 333         state->start = start;
 334         state->end = end;
 335
 336         set_state_bits(tree, state, bits);
 337
 338         node = tree_insert(&tree->state, end, &state->rb_node);
 339         if (node) {
 340                 struct extent_state *found;
 341                 found = rb_entry(node, struct extent_state, rb_node);
 342                 printk(KERN_ERR "btrfs found node %llu %llu on insert of "
 343                        "%llu %llu\n", (unsigned long long)found->start,
 344                        (unsigned long long)found->end,
 345                        (unsigned long long)start, (unsigned long long)end);
 346                 return -EEXIST;
 347         }
 348         state->tree = tree;
 349         merge_state(tree, state);
 350         return 0;
 351 }
 352
 353 static void split_cb(struct extent_io_tree *tree, struct extent_state *orig,
 354                      u64 split)
 355 {
 356         if (tree->ops && tree->ops->split_extent_hook)
 357                 tree->ops->split_extent_hook(tree->mapping->host, orig, split);
 358 }
 359
 360 /*
 361  * split a given extent state struct in two, inserting the preallocated
 362  * struct 'prealloc' as the newly created second half.  'split' indicates an
 363  * offset inside 'orig' where it should be split.
 364  *
 365  * Before calling,
 366  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
 367  * are two extent state structs in the tree:
 368  * prealloc: [orig->start, split - 1]
 369  * orig: [ split, orig->end ]
 370  *
 371  * The tree locks are not taken by this function. They need to be held
 372  * by the caller.
 373  */
 374 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 375                        struct extent_state *prealloc, u64 split)
 376 {
 377         struct rb_node *node;
 378
 379         split_cb(tree, orig, split);
 380
 381         prealloc->start = orig->start;
 382         prealloc->end = split - 1;
 383         prealloc->state = orig->state;
 384         orig->start = split;
 385
 386         node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node);
 387         if (node) {
 388                 free_extent_state(prealloc);
 389                 return -EEXIST;
 390         }
 391         prealloc->tree = tree;
 392         return 0;
 393 }
 394
 395 /*
 396  * utility function to clear some bits in an extent state struct.
 397  * it will optionally wake up any one waiting on this state (wake == 1), or
 398  * forcibly remove the state from the tree (delete == 1).
 399  *
 400  * If no bits are set on the state struct after clearing things, the
 401  * struct is freed and removed from the tree
 402  */
 403 static int clear_state_bit(struct extent_io_tree *tree,
 404                             struct extent_state *state,
 405                             int *bits, int wake)
 406 {
 407         int bits_to_clear = *bits & ~EXTENT_CTLBITS;
 408         int ret = state->state & bits_to_clear;
 409
 410         if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
 411                 u64 range = state->end - state->start + 1;
 412                 WARN_ON(range > tree->dirty_bytes);
 413                 tree->dirty_bytes -= range;
 414         }
 415         clear_state_cb(tree, state, bits);
 416         state->state &= ~bits_to_clear;
 417         if (wake)
 418                 wake_up(&state->wq);
 419         if (state->state == 0) {
 420                 if (state->tree) {
 421                         rb_erase(&state->rb_node, &tree->state);
 422                         state->tree = NULL;
 423                         free_extent_state(state);
 424                 } else {
 425                         WARN_ON(1);
 426                 }
 427         } else {
 428                 merge_state(tree, state);
 429         }
 430         return ret;
 431 }
 432
 433 static struct extent_state *
 434 alloc_extent_state_atomic(struct extent_state *prealloc)
 435 {
 436         if (!prealloc)
 437                 prealloc = alloc_extent_state(GFP_ATOMIC);
 438
 439         return prealloc;
 440 }
 441
 442 /*
 443  * clear some bits on a range in the tree.  This may require splitting
 444  * or inserting elements in the tree, so the gfp mask is used to
 445  * indicate which allocations or sleeping are allowed.
 446  *
 447  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
 448  * the given range from the tree regardless of state (ie for truncate).
 449  *
 450  * the range [start, end] is inclusive.
 451  *
 452  * This takes the tree lock, and returns < 0 on error, > 0 if any of the
 453  * bits were already set, or zero if none of the bits were already set.
 454  */
 455 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 456                      int bits, int wake, int delete,
 457                      struct extent_state **cached_state,
 458                      gfp_t mask)
 459 {
 460         struct extent_state *state;
 461         struct extent_state *cached;
 462         struct extent_state *prealloc = NULL;
 463         struct rb_node *next_node;
 464         struct rb_node *node;
 465         u64 last_end;
 466         int err;
 467         int set = 0;
 468         int clear = 0;
 469
 470         if (delete)
 471                 bits |= ~EXTENT_CTLBITS;
 472         bits |= EXTENT_FIRST_DELALLOC;
 473
 474         if (bits & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 475                 clear = 1;
 476 again:
 477         if (!prealloc && (mask & __GFP_WAIT)) {
 478                 prealloc = alloc_extent_state(mask);
 479                 if (!prealloc)
 480                         return -ENOMEM;
 481         }
 482
 483         spin_lock(&tree->lock);
 484         if (cached_state) {
 485                 cached = *cached_state;
 486
 487                 if (clear) {
 488                         *cached_state = NULL;
 489                         cached_state = NULL;
 490                 }
 491
 492                 if (cached && cached->tree && cached->start <= start &&
 493                     cached->end > start) {
 494                         if (clear)
 495                                 atomic_dec(&cached->refs);
 496                         state = cached;
 497                         goto hit_next;
 498                 }
 499                 if (clear)
 500                         free_extent_state(cached);
 501         }
 502         /*
 503          * this search will find the extents that end after
 504          * our range starts
 505          */
 506         node = tree_search(tree, start);
 507         if (!node)
 508                 goto out;
 509         state = rb_entry(node, struct extent_state, rb_node);
 510 hit_next:
 511         if (state->start > end)
 512                 goto out;
 513         WARN_ON(state->end < start);
 514         last_end = state->end;
 515
 516         if (state->end < end && !need_resched())
 517                 next_node = rb_next(&state->rb_node);
 518         else
 519                 next_node = NULL;
 520
 521         /* the state doesn't have the wanted bits, go ahead */
 522         if (!(state->state & bits))
 523                 goto next;
 524
 525         /*
 526          *     | ---- desired range ---- |
 527          *  | state | or
 528          *  | ------------- state -------------- |
 529          *
 530          * We need to split the extent we found, and may flip
 531          * bits on second half.
 532          *
 533          * If the extent we found extends past our range, we
 534          * just split and search again.  It'll get split again
 535          * the next time though.
 536          *
 537          * If the extent we found is inside our range, we clear
 538          * the desired bit on it.
 539          */
 540
 541         if (state->start < start) {
 542                 prealloc = alloc_extent_state_atomic(prealloc);
 543                 BUG_ON(!prealloc);
 544                 err = split_state(tree, state, prealloc, start);
 545                 BUG_ON(err == -EEXIST);
 546                 prealloc = NULL;
 547                 if (err)
 548                         goto out;
 549                 if (state->end <= end) {
 550                         set |= clear_state_bit(tree, state, &bits, wake);
 551                         if (last_end == (u64)-1)
 552                                 goto out;
 553                         start = last_end + 1;
 554                 }
 555                 goto search_again;
 556         }
 557         /*
 558          * | ---- desired range ---- |
 559          *                        | state |
 560          * We need to split the extent, and clear the bit
 561          * on the first half
 562          */
 563         if (state->start <= end && state->end > end) {
 564                 prealloc = alloc_extent_state_atomic(prealloc);
 565                 BUG_ON(!prealloc);
 566                 err = split_state(tree, state, prealloc, end + 1);
 567                 BUG_ON(err == -EEXIST);
 568                 if (wake)
 569                         wake_up(&state->wq);
 570
 571                 set |= clear_state_bit(tree, prealloc, &bits, wake);
 572
 573                 prealloc = NULL;
 574                 goto out;
 575         }
 576
 577         set |= clear_state_bit(tree, state, &bits, wake);
 578 next:
 579         if (last_end == (u64)-1)
 580                 goto out;
 581         start = last_end + 1;
 582         if (start <= end && next_node) {
 583                 state = rb_entry(next_node, struct extent_state,
 584                                  rb_node);
 585                 goto hit_next;
 586         }
 587         goto search_again;
 588
 589 out:
 590         spin_unlock(&tree->lock);
 591         if (prealloc)
 592                 free_extent_state(prealloc);
 593
 594         return set;
 595
 596 search_again:
 597         if (start > end)
 598                 goto out;
 599         spin_unlock(&tree->lock);
 600         if (mask & __GFP_WAIT)
 601                 cond_resched();
 602         goto again;
 603 }
 604
 605 static int wait_on_state(struct extent_io_tree *tree,
 606                          struct extent_state *state)
 607                 __releases(tree->lock)
 608                 __acquires(tree->lock)
 609 {
 610         DEFINE_WAIT(wait);
 611         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
 612         spin_unlock(&tree->lock);
 613         schedule();
 614         spin_lock(&tree->lock);
 615         finish_wait(&state->wq, &wait);
 616         return 0;
 617 }
 618
 619 /*
 620  * waits for one or more bits to clear on a range in the state tree.
 621  * The range [start, end] is inclusive.
 622  * The tree lock is taken by this function
 623  */
 624 int wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, int bits)
 625 {
 626         struct extent_state *state;
 627         struct rb_node *node;
 628
 629         spin_lock(&tree->lock);
 630 again:
 631         while (1) {
 632                 /*
 633                  * this search will find all the extents that end after
 634                  * our range starts
 635                  */
 636                 node = tree_search(tree, start);
 637                 if (!node)
 638                         break;
 639
 640                 state = rb_entry(node, struct extent_state, rb_node);
 641
 642                 if (state->start > end)
 643                         goto out;
 644
 645                 if (state->state & bits) {
 646                         start = state->start;
 647                         atomic_inc(&state->refs);
 648                         wait_on_state(tree, state);
 649                         free_extent_state(state);
 650                         goto again;
 651                 }
 652                 start = state->end + 1;
 653
 654                 if (start > end)
 655                         break;
 656
 657                 cond_resched_lock(&tree->lock);
 658         }
 659 out:
 660         spin_unlock(&tree->lock);
 661         return 0;
 662 }
 663
 664 static void set_state_bits(struct extent_io_tree *tree,
 665                            struct extent_state *state,
 666                            int *bits)
 667 {
 668         int bits_to_set = *bits & ~EXTENT_CTLBITS;
 669
 670         set_state_cb(tree, state, bits);
 671         if ((bits_to_set & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
 672                 u64 range = state->end - state->start + 1;
 673                 tree->dirty_bytes += range;
 674         }
 675         state->state |= bits_to_set;
 676 }
 677
 678 static void cache_state(struct extent_state *state,
 679                         struct extent_state **cached_ptr)
 680 {
 681         if (cached_ptr && !(*cached_ptr)) {
 682                 if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY)) {
 683                         *cached_ptr = state;
 684                         atomic_inc(&state->refs);
 685                 }
 686         }
 687 }
 688
 689 static void uncache_state(struct extent_state **cached_ptr)
 690 {
 691         if (cached_ptr && (*cached_ptr)) {
 692                 struct extent_state *state = *cached_ptr;
 693                 *cached_ptr = NULL;
 694                 free_extent_state(state);
 695         }
 696 }
 697
 698 /*
 699  * set some bits on a range in the tree.  This may require allocations or
 700  * sleeping, so the gfp mask is used to indicate what is allowed.
 701  *
 702  * If any of the exclusive bits are set, this will fail with -EEXIST if some
 703  * part of the range already has the desired bits set.  The start of the
 704  * existing range is returned in failed_start in this case.
 705  *
 706  * [start, end] is inclusive This takes the tree lock.
 707  */
 708
 709 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 710                    int bits, int exclusive_bits, u64 *failed_start,
 711                    struct extent_state **cached_state, gfp_t mask)
 712 {
 713         struct extent_state *state;
 714         struct extent_state *prealloc = NULL;
 715         struct rb_node *node;
 716         int err = 0;
 717         u64 last_start;
 718         u64 last_end;
 719
 720         bits |= EXTENT_FIRST_DELALLOC;
 721 again:
 722         if (!prealloc && (mask & __GFP_WAIT)) {
 723                 prealloc = alloc_extent_state(mask);
 724                 BUG_ON(!prealloc);
 725         }
 726
 727         spin_lock(&tree->lock);
 728         if (cached_state && *cached_state) {
 729                 state = *cached_state;
 730                 if (state->start <= start && state->end > start &&
 731                     state->tree) {
 732                         node = &state->rb_node;
 733                         goto hit_next;
 734                 }
 735         }
 736         /*
 737          * this search will find all the extents that end after
 738          * our range starts.
 739          */
 740         node = tree_search(tree, start);
 741         if (!node) {
 742                 prealloc = alloc_extent_state_atomic(prealloc);
 743                 BUG_ON(!prealloc);
 744                 err = insert_state(tree, prealloc, start, end, &bits);
 745                 prealloc = NULL;
 746                 BUG_ON(err == -EEXIST);
 747                 goto out;
 748         }
 749         state = rb_entry(node, struct extent_state, rb_node);
 750 hit_next:
 751         last_start = state->start;
 752         last_end = state->end;
 753
 754         /*
 755          * | ---- desired range ---- |
 756          * | state |
 757          *
 758          * Just lock what we found and keep going
 759          */
 760         if (state->start == start && state->end <= end) {
 761                 struct rb_node *next_node;
 762                 if (state->state & exclusive_bits) {
 763                         *failed_start = state->start;
 764                         err = -EEXIST;
 765                         goto out;
 766                 }
 767
 768                 set_state_bits(tree, state, &bits);
 769
 770                 cache_state(state, cached_state);
 771                 merge_state(tree, state);
 772                 if (last_end == (u64)-1)
 773                         goto out;
 774
 775                 start = last_end + 1;
 776                 next_node = rb_next(&state->rb_node);
 777                 if (next_node && start < end && prealloc && !need_resched()) {
 778                         state = rb_entry(next_node, struct extent_state,
 779                                          rb_node);
 780                         if (state->start == start)
 781                                 goto hit_next;
 782                 }
 783                 goto search_again;
 784         }
 785
 786         /*
 787          *     | ---- desired range ---- |
 788          * | state |
 789          *   or
 790          * | ------------- state -------------- |
 791          *
 792          * We need to split the extent we found, and may flip bits on
 793          * second half.
 794          *
 795          * If the extent we found extends past our
 796          * range, we just split and search again.  It'll get split
 797          * again the next time though.
 798          *
 799          * If the extent we found is inside our range, we set the
 800          * desired bit on it.
 801          */
 802         if (state->start < start) {
 803                 if (state->state & exclusive_bits) {
 804                         *failed_start = start;
 805                         err = -EEXIST;
 806                         goto out;
 807                 }
 808
 809                 prealloc = alloc_extent_state_atomic(prealloc);
 810                 BUG_ON(!prealloc);
 811                 err = split_state(tree, state, prealloc, start);
 812                 BUG_ON(err == -EEXIST);
 813                 prealloc = NULL;
 814                 if (err)
 815                         goto out;
 816                 if (state->end <= end) {
 817                         set_state_bits(tree, state, &bits);
 818                         cache_state(state, cached_state);
 819                         merge_state(tree, state);
 820                         if (last_end == (u64)-1)
 821                                 goto out;
 822                         start = last_end + 1;
 823                 }
 824                 goto search_again;
 825         }
 826         /*
 827          * | ---- desired range ---- |
 828          *     | state | or               | state |
 829          *
 830          * There's a hole, we need to insert something in it and
 831          * ignore the extent we found.
 832          */
 833         if (state->start > start) {
 834                 u64 this_end;
 835                 if (end < last_start)
 836                         this_end = end;
 837                 else
 838                         this_end = last_start - 1;
 839
 840                 prealloc = alloc_extent_state_atomic(prealloc);
 841                 BUG_ON(!prealloc);
 842
 843                 /*
 844                  * Avoid to free 'prealloc' if it can be merged with
 845                  * the later extent.
 846                  */
 847                 err = insert_state(tree, prealloc, start, this_end,
 848                                    &bits);
 849                 BUG_ON(err == -EEXIST);
 850                 if (err) {
 851                         free_extent_state(prealloc);
 852                         prealloc = NULL;
 853                         goto out;
 854                 }
 855                 cache_state(prealloc, cached_state);
 856                 prealloc = NULL;
 857                 start = this_end + 1;
 858                 goto search_again;
 859         }
 860         /*
 861          * | ---- desired range ---- |
 862          *                        | state |
 863          * We need to split the extent, and set the bit
 864          * on the first half
 865          */
 866         if (state->start <= end && state->end > end) {
 867                 if (state->state & exclusive_bits) {
 868                         *failed_start = start;
 869                         err = -EEXIST;
 870                         goto out;
 871                 }
 872
 873                 prealloc = alloc_extent_state_atomic(prealloc);
 874                 BUG_ON(!prealloc);
 875                 err = split_state(tree, state, prealloc, end + 1);
 876                 BUG_ON(err == -EEXIST);
 877
 878                 set_state_bits(tree, prealloc, &bits);
 879                 cache_state(prealloc, cached_state);
 880                 merge_state(tree, prealloc);
 881                 prealloc = NULL;
 882                 goto out;
 883         }
 884
 885         goto search_again;
 886
 887 out:
 888         spin_unlock(&tree->lock);
 889         if (prealloc)
 890                 free_extent_state(prealloc);
 891
 892         return err;
 893
 894 search_again:
 895         if (start > end)
 896                 goto out;
 897         spin_unlock(&tree->lock);
 898         if (mask & __GFP_WAIT)
 899                 cond_resched();
 900         goto again;
 901 }
 902
 903 /**
 904  * convert_extent - convert all bits in a given range from one bit to another
 905  * @tree:       the io tree to search
 906  * @start:      the start offset in bytes
 907  * @end:        the end offset in bytes (inclusive)
 908  * @bits:       the bits to set in this range
 909  * @clear_bits: the bits to clear in this range
 910  * @mask:       the allocation mask
 911  *
 912  * This will go through and set bits for the given range.  If any states exist
 913  * already in this range they are set with the given bit and cleared of the
 914  * clear_bits.  This is only meant to be used by things that are mergeable, ie
 915  * converting from say DELALLOC to DIRTY.  This is not meant to be used with
 916  * boundary bits like LOCK.
 917  */
 918 int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 919                        int bits, int clear_bits, gfp_t mask)
 920 {
 921         struct extent_state *state;
 922         struct extent_state *prealloc = NULL;
 923         struct rb_node *node;
 924         int err = 0;
 925         u64 last_start;
 926         u64 last_end;
 927
 928 again:
 929         if (!prealloc && (mask & __GFP_WAIT)) {
 930                 prealloc = alloc_extent_state(mask);
 931                 if (!prealloc)
 932                         return -ENOMEM;
 933         }
 934
 935         spin_lock(&tree->lock);
 936         /*
 937          * this search will find all the extents that end after
 938          * our range starts.
 939          */
 940         node = tree_search(tree, start);
 941         if (!node) {
 942                 prealloc = alloc_extent_state_atomic(prealloc);
 943                 if (!prealloc) {
 944                         err = -ENOMEM;
 945                         goto out;
 946                 }
 947                 err = insert_state(tree, prealloc, start, end, &bits);
 948                 prealloc = NULL;
 949                 BUG_ON(err == -EEXIST);
 950                 goto out;
 951         }
 952         state = rb_entry(node, struct extent_state, rb_node);
 953 hit_next:
 954         last_start = state->start;
 955         last_end = state->end;
 956
 957         /*
 958          * | ---- desired range ---- |
 959          * | state |
 960          *
 961          * Just lock what we found and keep going
 962          */
 963         if (state->start == start && state->end <= end) {
 964                 struct rb_node *next_node;
 965
 966                 set_state_bits(tree, state, &bits);
 967                 clear_state_bit(tree, state, &clear_bits, 0);
 968                 if (last_end == (u64)-1)
 969                         goto out;
 970
 971                 start = last_end + 1;
 972                 next_node = rb_next(&state->rb_node);
 973                 if (next_node && start < end && prealloc && !need_resched()) {
 974                         state = rb_entry(next_node, struct extent_state,
 975                                          rb_node);
 976                         if (state->start == start)
 977                                 goto hit_next;
 978                 }
 979                 goto search_again;
 980         }
 981
 982         /*
 983          *     | ---- desired range ---- |
 984          * | state |
 985          *   or
 986          * | ------------- state -------------- |
 987          *
 988          * We need to split the extent we found, and may flip bits on
 989          * second half.
 990          *
 991          * If the extent we found extends past our
 992          * range, we just split and search again.  It'll get split
 993          * again the next time though.
 994          *
 995          * If the extent we found is inside our range, we set the
 996          * desired bit on it.
 997          */
 998         if (state->start < start) {
 999                 prealloc = alloc_extent_state_atomic(prealloc);
1000                 if (!prealloc) {
1001                         err = -ENOMEM;
1002                         goto out;
1003                 }
1004                 err = split_state(tree, state, prealloc, start);
1005                 BUG_ON(err == -EEXIST);
1006                 prealloc = NULL;
1007                 if (err)
1008                         goto out;
1009                 if (state->end <= end) {
1010                         set_state_bits(tree, state, &bits);
1011                         clear_state_bit(tree, state, &clear_bits, 0);
1012                         if (last_end == (u64)-1)
1013                                 goto out;
1014                         start = last_end + 1;
1015                 }
1016                 goto search_again;
1017         }
1018         /*
1019          * | ---- desired range ---- |
1020          *     | state | or               | state |
1021          *
1022          * There's a hole, we need to insert something in it and
1023          * ignore the extent we found.
1024          */
1025         if (state->start > start) {
1026                 u64 this_end;
1027                 if (end < last_start)
1028                         this_end = end;
1029                 else
1030                         this_end = last_start - 1;
1031
1032                 prealloc = alloc_extent_state_atomic(prealloc);
1033                 if (!prealloc) {
1034                         err = -ENOMEM;
1035                         goto out;
1036                 }
1037
1038                 /*
1039                  * Avoid to free 'prealloc' if it can be merged with
1040                  * the later extent.
1041                  */
1042                 err = insert_state(tree, prealloc, start, this_end,
1043                                    &bits);
1044                 BUG_ON(err == -EEXIST);
1045                 if (err) {
1046                         free_extent_state(prealloc);
1047                         prealloc = NULL;
1048                         goto out;
1049                 }
1050                 prealloc = NULL;
1051                 start = this_end + 1;
1052                 goto search_again;
1053         }
1054         /*
1055          * | ---- desired range ---- |
1056          *                        | state |
1057          * We need to split the extent, and set the bit
1058          * on the first half
1059          */
1060         if (state->start <= end && state->end > end) {
1061                 prealloc = alloc_extent_state_atomic(prealloc);
1062                 if (!prealloc) {
1063                         err = -ENOMEM;
1064                         goto out;
1065                 }
1066
1067                 err = split_state(tree, state, prealloc, end + 1);
1068                 BUG_ON(err == -EEXIST);
1069
1070                 set_state_bits(tree, prealloc, &bits);
1071                 clear_state_bit(tree, prealloc, &clear_bits, 0);
1072                 prealloc = NULL;
1073                 goto out;
1074         }
1075
1076         goto search_again;
1077
1078 out:
1079         spin_unlock(&tree->lock);
1080         if (prealloc)
1081                 free_extent_state(prealloc);
1082
1083         return err;
1084
1085 search_again:
1086         if (start > end)
1087                 goto out;
1088         spin_unlock(&tree->lock);
1089         if (mask & __GFP_WAIT)
1090                 cond_resched();
1091         goto again;
1092 }
1093
1094 /* wrappers around set/clear extent bit */
1095 int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
1096                      gfp_t mask)
1097 {
1098         return set_extent_bit(tree, start, end, EXTENT_DIRTY, 0, NULL,
1099                               NULL, mask);
1100 }
1101
1102 int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1103                     int bits, gfp_t mask)
1104 {
1105         return set_extent_bit(tree, start, end, bits, 0, NULL,
1106                               NULL, mask);
1107 }
1108
1109 int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1110                       int bits, gfp_t mask)
1111 {
1112         return clear_extent_bit(tree, start, end, bits, 0, 0, NULL, mask);
1113 }
1114
1115 int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
1116                         struct extent_state **cached_state, gfp_t mask)
1117 {
1118         return set_extent_bit(tree, start, end,
1119                               EXTENT_DELALLOC | EXTENT_UPTODATE,
1120                               0, NULL, cached_state, mask);
1121 }
1122
1123 int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
1124                        gfp_t mask)
1125 {
1126         return clear_extent_bit(tree, start, end,
1127                                 EXTENT_DIRTY | EXTENT_DELALLOC |
1128                                 EXTENT_DO_ACCOUNTING, 0, 0, NULL, mask);
1129 }
1130
1131 int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
1132                      gfp_t mask)
1133 {
1134         return set_extent_bit(tree, start, end, EXTENT_NEW, 0, NULL,
1135                               NULL, mask);
1136 }
1137
1138 int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
1139                         struct extent_state **cached_state, gfp_t mask)
1140 {
1141         return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0,
1142                               NULL, cached_state, mask);
1143 }
1144
1145 static int clear_extent_uptodate(struct extent_io_tree *tree, u64 start,
1146                                  u64 end, struct extent_state **cached_state,
1147                                  gfp_t mask)
1148 {
1149         return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
1150                                 cached_state, mask);
1151 }
1152
1153 /*
1154  * either insert or lock state struct between start and end use mask to tell
1155  * us if waiting is desired.
1156  */
1157 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1158                      int bits, struct extent_state **cached_state, gfp_t mask)
1159 {
1160         int err;
1161         u64 failed_start;
1162         while (1) {
1163                 err = set_extent_bit(tree, start, end, EXTENT_LOCKED | bits,
1164                                      EXTENT_LOCKED, &failed_start,
1165                                      cached_state, mask);
1166                 if (err == -EEXIST && (mask & __GFP_WAIT)) {
1167                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1168                         start = failed_start;
1169                 } else {
1170                         break;
1171                 }
1172                 WARN_ON(start > end);
1173         }
1174         return err;
1175 }
1176
1177 int lock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask)
1178 {
1179         return lock_extent_bits(tree, start, end, 0, NULL, mask);
1180 }
1181
1182 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end,
1183                     gfp_t mask)
1184 {
1185         int err;
1186         u64 failed_start;
1187
1188         err = set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1189                              &failed_start, NULL, mask);
1190         if (err == -EEXIST) {
1191                 if (failed_start > start)
1192                         clear_extent_bit(tree, start, failed_start - 1,
1193                                          EXTENT_LOCKED, 1, 0, NULL, mask);
1194                 return 0;
1195         }
1196         return 1;
1197 }
1198
1199 int unlock_extent_cached(struct extent_io_tree *tree, u64 start, u64 end,
1200                          struct extent_state **cached, gfp_t mask)
1201 {
1202         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
1203                                 mask);
1204 }
1205
1206 int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask)
1207 {
1208         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL,
1209                                 mask);
1210 }
1211
1212 /*
1213  * helper function to set both pages and extents in the tree writeback
1214  */
1215 static int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1216 {
1217         unsigned long index = start >> PAGE_CACHE_SHIFT;
1218         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1219         struct page *page;
1220
1221         while (index <= end_index) {
1222                 page = find_get_page(tree->mapping, index);
1223                 BUG_ON(!page);
1224                 set_page_writeback(page);
1225                 page_cache_release(page);
1226                 index++;
1227         }
1228         return 0;
1229 }
1230
1231 /* find the first state struct with 'bits' set after 'start', and
1232  * return it.  tree->lock must be held.  NULL will returned if
1233  * nothing was found after 'start'
1234  */
1235 struct extent_state *find_first_extent_bit_state(struct extent_io_tree *tree,
1236                                                  u64 start, int bits)
1237 {
1238         struct rb_node *node;
1239         struct extent_state *state;
1240
1241         /*
1242          * this search will find all the extents that end after
1243          * our range starts.
1244          */
1245         node = tree_search(tree, start);
1246         if (!node)
1247                 goto out;
1248
1249         while (1) {
1250                 state = rb_entry(node, struct extent_state, rb_node);
1251                 if (state->end >= start && (state->state & bits))
1252                         return state;
1253
1254                 node = rb_next(node);
1255                 if (!node)
1256                         break;
1257         }
1258 out:
1259         return NULL;
1260 }
1261
1262 /*
1263  * find the first offset in the io tree with 'bits' set. zero is
1264  * returned if we find something, and *start_ret and *end_ret are
1265  * set to reflect the state struct that was found.
1266  *
1267  * If nothing was found, 1 is returned, < 0 on error
1268  */
1269 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1270                           u64 *start_ret, u64 *end_ret, int bits)
1271 {
1272         struct extent_state *state;
1273         int ret = 1;
1274
1275         spin_lock(&tree->lock);
1276         state = find_first_extent_bit_state(tree, start, bits);
1277         if (state) {
1278                 *start_ret = state->start;
1279                 *end_ret = state->end;
1280                 ret = 0;
1281         }
1282         spin_unlock(&tree->lock);
1283         return ret;
1284 }
1285
1286 /*
1287  * find a contiguous range of bytes in the file marked as delalloc, not
1288  * more than 'max_bytes'.  start and end are used to return the range,
1289  *
1290  * 1 is returned if we find something, 0 if nothing was in the tree
1291  */
1292 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
1293                                         u64 *start, u64 *end, u64 max_bytes,
1294                                         struct extent_state **cached_state)
1295 {
1296         struct rb_node *node;
1297         struct extent_state *state;
1298         u64 cur_start = *start;
1299         u64 found = 0;
1300         u64 total_bytes = 0;
1301
1302         spin_lock(&tree->lock);
1303
1304         /*
1305          * this search will find all the extents that end after
1306          * our range starts.
1307          */
1308         node = tree_search(tree, cur_start);
1309         if (!node) {
1310                 if (!found)
1311                         *end = (u64)-1;
1312                 goto out;
1313         }
1314
1315         while (1) {
1316                 state = rb_entry(node, struct extent_state, rb_node);
1317                 if (found && (state->start != cur_start ||
1318                               (state->state & EXTENT_BOUNDARY))) {
1319                         goto out;
1320                 }
1321                 if (!(state->state & EXTENT_DELALLOC)) {
1322                         if (!found)
1323                                 *end = state->end;
1324                         goto out;
1325                 }
1326                 if (!found) {
1327                         *start = state->start;
1328                         *cached_state = state;
1329                         atomic_inc(&state->refs);
1330                 }
1331                 found++;
1332                 *end = state->end;
1333                 cur_start = state->end + 1;
1334                 node = rb_next(node);
1335                 if (!node)
1336                         break;
1337                 total_bytes += state->end - state->start + 1;
1338                 if (total_bytes >= max_bytes)
1339                         break;
1340         }
1341 out:
1342         spin_unlock(&tree->lock);
1343         return found;
1344 }
1345
1346 static noinline int __unlock_for_delalloc(struct inode *inode,
1347                                           struct page *locked_page,
1348                                           u64 start, u64 end)
1349 {
1350         int ret;
1351         struct page *pages[16];
1352         unsigned long index = start >> PAGE_CACHE_SHIFT;
1353         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1354         unsigned long nr_pages = end_index - index + 1;
1355         int i;
1356
1357         if (index == locked_page->index && end_index == index)
1358                 return 0;
1359
1360         while (nr_pages > 0) {
1361                 ret = find_get_pages_contig(inode->i_mapping, index,
1362                                      min_t(unsigned long, nr_pages,
1363                                      ARRAY_SIZE(pages)), pages);
1364                 for (i = 0; i < ret; i++) {
1365                         if (pages[i] != locked_page)
1366                                 unlock_page(pages[i]);
1367                         page_cache_release(pages[i]);
1368                 }
1369                 nr_pages -= ret;
1370                 index += ret;
1371                 cond_resched();
1372         }
1373         return 0;
1374 }
1375
1376 static noinline int lock_delalloc_pages(struct inode *inode,
1377                                         struct page *locked_page,
1378                                         u64 delalloc_start,
1379                                         u64 delalloc_end)
1380 {
1381         unsigned long index = delalloc_start >> PAGE_CACHE_SHIFT;
1382         unsigned long start_index = index;
1383         unsigned long end_index = delalloc_end >> PAGE_CACHE_SHIFT;
1384         unsigned long pages_locked = 0;
1385         struct page *pages[16];
1386         unsigned long nrpages;
1387         int ret;
1388         int i;
1389
1390         /* the caller is responsible for locking the start index */
1391         if (index == locked_page->index && index == end_index)
1392                 return 0;
1393
1394         /* skip the page at the start index */
1395         nrpages = end_index - index + 1;
1396         while (nrpages > 0) {
1397                 ret = find_get_pages_contig(inode->i_mapping, index,
1398                                      min_t(unsigned long,
1399                                      nrpages, ARRAY_SIZE(pages)), pages);
1400                 if (ret == 0) {
1401                         ret = -EAGAIN;
1402                         goto done;
1403                 }
1404                 /* now we have an array of pages, lock them all */
1405                 for (i = 0; i < ret; i++) {
1406                         /*
1407                          * the caller is taking responsibility for
1408                          * locked_page
1409                          */
1410                         if (pages[i] != locked_page) {
1411                                 lock_page(pages[i]);
1412                                 if (!PageDirty(pages[i]) ||
1413                                     pages[i]->mapping != inode->i_mapping) {
1414                                         ret = -EAGAIN;
1415                                         unlock_page(pages[i]);
1416                                         page_cache_release(pages[i]);
1417                                         goto done;
1418                                 }
1419                         }
1420                         page_cache_release(pages[i]);
1421                         pages_locked++;
1422                 }
1423                 nrpages -= ret;
1424                 index += ret;
1425                 cond_resched();
1426         }
1427         ret = 0;
1428 done:
1429         if (ret && pages_locked) {
1430                 __unlock_for_delalloc(inode, locked_page,
1431                               delalloc_start,
1432                               ((u64)(start_index + pages_locked - 1)) <<
1433                               PAGE_CACHE_SHIFT);
1434         }
1435         return ret;
1436 }
1437
1438 /*
1439  * find a contiguous range of bytes in the file marked as delalloc, not
1440  * more than 'max_bytes'.  start and end are used to return the range,
1441  *
1442  * 1 is returned if we find something, 0 if nothing was in the tree
1443  */
1444 static noinline u64 find_lock_delalloc_range(struct inode *inode,
1445                                              struct extent_io_tree *tree,
1446                                              struct page *locked_page,
1447                                              u64 *start, u64 *end,
1448                                              u64 max_bytes)
1449 {
1450         u64 delalloc_start;
1451         u64 delalloc_end;
1452         u64 found;
1453         struct extent_state *cached_state = NULL;
1454         int ret;
1455         int loops = 0;
1456
1457 again:
1458         /* step one, find a bunch of delalloc bytes starting at start */
1459         delalloc_start = *start;
1460         delalloc_end = 0;
1461         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1462                                     max_bytes, &cached_state);
1463         if (!found || delalloc_end <= *start) {
1464                 *start = delalloc_start;
1465                 *end = delalloc_end;
1466                 free_extent_state(cached_state);
1467                 return found;
1468         }
1469
1470         /*
1471          * start comes from the offset of locked_page.  We have to lock
1472          * pages in order, so we can't process delalloc bytes before
1473          * locked_page
1474          */
1475         if (delalloc_start < *start)
1476                 delalloc_start = *start;
1477
1478         /*
1479          * make sure to limit the number of pages we try to lock down
1480          * if we're looping.
1481          */
1482         if (delalloc_end + 1 - delalloc_start > max_bytes && loops)
1483                 delalloc_end = delalloc_start + PAGE_CACHE_SIZE - 1;
1484
1485         /* step two, lock all the pages after the page that has start */
1486         ret = lock_delalloc_pages(inode, locked_page,
1487                                   delalloc_start, delalloc_end);
1488         if (ret == -EAGAIN) {
1489                 /* some of the pages are gone, lets avoid looping by
1490                  * shortening the size of the delalloc range we're searching
1491                  */
1492                 free_extent_state(cached_state);
1493                 if (!loops) {
1494                         unsigned long offset = (*start) & (PAGE_CACHE_SIZE - 1);
1495                         max_bytes = PAGE_CACHE_SIZE - offset;
1496                         loops = 1;
1497                         goto again;
1498                 } else {
1499                         found = 0;
1500                         goto out_failed;
1501                 }
1502         }
1503         BUG_ON(ret);
1504
1505         /* step three, lock the state bits for the whole range */
1506         lock_extent_bits(tree, delalloc_start, delalloc_end,
1507                          0, &cached_state, GFP_NOFS);
1508
1509         /* then test to make sure it is all still delalloc */
1510         ret = test_range_bit(tree, delalloc_start, delalloc_end,
1511                              EXTENT_DELALLOC, 1, cached_state);
1512         if (!ret) {
1513                 unlock_extent_cached(tree, delalloc_start, delalloc_end,
1514                                      &cached_state, GFP_NOFS);
1515                 __unlock_for_delalloc(inode, locked_page,
1516                               delalloc_start, delalloc_end);
1517                 cond_resched();
1518                 goto again;
1519         }
1520         free_extent_state(cached_state);
1521         *start = delalloc_start;
1522         *end = delalloc_end;
1523 out_failed:
1524         return found;
1525 }
1526
1527 int extent_clear_unlock_delalloc(struct inode *inode,
1528                                 struct extent_io_tree *tree,
1529                                 u64 start, u64 end, struct page *locked_page,
1530                                 unsigned long op)
1531 {
1532         int ret;
1533         struct page *pages[16];
1534         unsigned long index = start >> PAGE_CACHE_SHIFT;
1535         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1536         unsigned long nr_pages = end_index - index + 1;
1537         int i;
1538         int clear_bits = 0;
1539
1540         if (op & EXTENT_CLEAR_UNLOCK)
1541                 clear_bits |= EXTENT_LOCKED;
1542         if (op & EXTENT_CLEAR_DIRTY)
1543                 clear_bits |= EXTENT_DIRTY;
1544
1545         if (op & EXTENT_CLEAR_DELALLOC)
1546                 clear_bits |= EXTENT_DELALLOC;
1547
1548         clear_extent_bit(tree, start, end, clear_bits, 1, 0, NULL, GFP_NOFS);
1549         if (!(op & (EXTENT_CLEAR_UNLOCK_PAGE | EXTENT_CLEAR_DIRTY |
1550                     EXTENT_SET_WRITEBACK | EXTENT_END_WRITEBACK |
1551                     EXTENT_SET_PRIVATE2)))
1552                 return 0;
1553
1554         while (nr_pages > 0) {
1555                 ret = find_get_pages_contig(inode->i_mapping, index,
1556                                      min_t(unsigned long,
1557                                      nr_pages, ARRAY_SIZE(pages)), pages);
1558                 for (i = 0; i < ret; i++) {
1559
1560                         if (op & EXTENT_SET_PRIVATE2)
1561                                 SetPagePrivate2(pages[i]);
1562
1563                         if (pages[i] == locked_page) {
1564                                 page_cache_release(pages[i]);
1565                                 continue;
1566                         }
1567                         if (op & EXTENT_CLEAR_DIRTY)
1568                                 clear_page_dirty_for_io(pages[i]);
1569                         if (op & EXTENT_SET_WRITEBACK)
1570                                 set_page_writeback(pages[i]);
1571                         if (op & EXTENT_END_WRITEBACK)
1572                                 end_page_writeback(pages[i]);
1573                         if (op & EXTENT_CLEAR_UNLOCK_PAGE)
1574                                 unlock_page(pages[i]);
1575                         page_cache_release(pages[i]);
1576                 }
1577                 nr_pages -= ret;
1578                 index += ret;
1579                 cond_resched();
1580         }
1581         return 0;
1582 }
1583
1584 /*
1585  * count the number of bytes in the tree that have a given bit(s)
1586  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1587  * cached.  The total number found is returned.
1588  */
1589 u64 count_range_bits(struct extent_io_tree *tree,
1590                      u64 *start, u64 search_end, u64 max_bytes,
1591                      unsigned long bits, int contig)
1592 {
1593         struct rb_node *node;
1594         struct extent_state *state;
1595         u64 cur_start = *start;
1596         u64 total_bytes = 0;
1597         u64 last = 0;
1598         int found = 0;
1599
1600         if (search_end <= cur_start) {
1601                 WARN_ON(1);
1602                 return 0;
1603         }
1604
1605         spin_lock(&tree->lock);
1606         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1607                 total_bytes = tree->dirty_bytes;
1608                 goto out;
1609         }
1610         /*
1611          * this search will find all the extents that end after
1612          * our range starts.
1613          */
1614         node = tree_search(tree, cur_start);
1615         if (!node)
1616                 goto out;
1617
1618         while (1) {
1619                 state = rb_entry(node, struct extent_state, rb_node);
1620                 if (state->start > search_end)
1621                         break;
1622                 if (contig && found && state->start > last + 1)
1623                         break;
1624                 if (state->end >= cur_start && (state->state & bits) == bits) {
1625                         total_bytes += min(search_end, state->end) + 1 -
1626                                        max(cur_start, state->start);
1627                         if (total_bytes >= max_bytes)
1628                                 break;
1629                         if (!found) {
1630                                 *start = max(cur_start, state->start);
1631                                 found = 1;
1632                         }
1633                         last = state->end;
1634                 } else if (contig && found) {
1635                         break;
1636                 }
1637                 node = rb_next(node);
1638                 if (!node)
1639                         break;
1640         }
1641 out:
1642         spin_unlock(&tree->lock);
1643         return total_bytes;
1644 }
1645
1646 /*
1647  * set the private field for a given byte offset in the tree.  If there isn't
1648  * an extent_state there already, this does nothing.
1649  */
1650 int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
1651 {
1652         struct rb_node *node;
1653         struct extent_state *state;
1654         int ret = 0;
1655
1656         spin_lock(&tree->lock);
1657         /*
1658          * this search will find all the extents that end after
1659          * our range starts.
1660          */
1661         node = tree_search(tree, start);
1662         if (!node) {
1663                 ret = -ENOENT;
1664                 goto out;
1665         }
1666         state = rb_entry(node, struct extent_state, rb_node);
1667         if (state->start != start) {
1668                 ret = -ENOENT;
1669                 goto out;
1670         }
1671         state->private = private;
1672 out:
1673         spin_unlock(&tree->lock);
1674         return ret;
1675 }
1676
1677 int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
1678 {
1679         struct rb_node *node;
1680         struct extent_state *state;
1681         int ret = 0;
1682
1683         spin_lock(&tree->lock);
1684         /*
1685          * this search will find all the extents that end after
1686          * our range starts.
1687          */
1688         node = tree_search(tree, start);
1689         if (!node) {
1690                 ret = -ENOENT;
1691                 goto out;
1692         }
1693         state = rb_entry(node, struct extent_state, rb_node);
1694         if (state->start != start) {
1695                 ret = -ENOENT;
1696                 goto out;
1697         }
1698         *private = state->private;
1699 out:
1700         spin_unlock(&tree->lock);
1701         return ret;
1702 }
1703
1704 /*
1705  * searches a range in the state tree for a given mask.
1706  * If 'filled' == 1, this returns 1 only if every extent in the tree
1707  * has the bits set.  Otherwise, 1 is returned if any bit in the
1708  * range is found set.
1709  */
1710 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
1711                    int bits, int filled, struct extent_state *cached)
1712 {
1713         struct extent_state *state = NULL;
1714         struct rb_node *node;
1715         int bitset = 0;
1716
1717         spin_lock(&tree->lock);
1718         if (cached && cached->tree && cached->start <= start &&
1719             cached->end > start)
1720                 node = &cached->rb_node;
1721         else
1722                 node = tree_search(tree, start);
1723         while (node && start <= end) {
1724                 state = rb_entry(node, struct extent_state, rb_node);
1725
1726                 if (filled && state->start > start) {
1727                         bitset = 0;
1728                         break;
1729                 }
1730
1731                 if (state->start > end)
1732                         break;
1733
1734                 if (state->state & bits) {
1735                         bitset = 1;
1736                         if (!filled)
1737                                 break;
1738                 } else if (filled) {
1739                         bitset = 0;
1740                         break;
1741                 }
1742
1743                 if (state->end == (u64)-1)
1744                         break;
1745
1746                 start = state->end + 1;
1747                 if (start > end)
1748                         break;
1749                 node = rb_next(node);
1750                 if (!node) {
1751                         if (filled)
1752                                 bitset = 0;
1753                         break;
1754                 }
1755         }
1756         spin_unlock(&tree->lock);
1757         return bitset;
1758 }
1759
1760 /*
1761  * helper function to set a given page up to date if all the
1762  * extents in the tree for that page are up to date
1763  */
1764 static int check_page_uptodate(struct extent_io_tree *tree,
1765                                struct page *page)
1766 {
1767         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1768         u64 end = start + PAGE_CACHE_SIZE - 1;
1769         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
1770                 SetPageUptodate(page);
1771         return 0;
1772 }
1773
1774 /*
1775  * helper function to unlock a page if all the extents in the tree
1776  * for that page are unlocked
1777  */
1778 static int check_page_locked(struct extent_io_tree *tree,
1779                              struct page *page)
1780 {
1781         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1782         u64 end = start + PAGE_CACHE_SIZE - 1;
1783         if (!test_range_bit(tree, start, end, EXTENT_LOCKED, 0, NULL))
1784                 unlock_page(page);
1785         return 0;
1786 }
1787
1788 /*
1789  * helper function to end page writeback if all the extents
1790  * in the tree for that page are done with writeback
1791  */
1792 static int check_page_writeback(struct extent_io_tree *tree,
1793                              struct page *page)
1794 {
1795         end_page_writeback(page);
1796         return 0;
1797 }
1798
1799 /*
1800  * When IO fails, either with EIO or csum verification fails, we
1801  * try other mirrors that might have a good copy of the data.  This
1802  * io_failure_record is used to record state as we go through all the
1803  * mirrors.  If another mirror has good data, the page is set up to date
1804  * and things continue.  If a good mirror can't be found, the original
1805  * bio end_io callback is called to indicate things have failed.
1806  */
1807 struct io_failure_record {
1808         struct page *page;
1809         u64 start;
1810         u64 len;
1811         u64 logical;
1812         unsigned long bio_flags;
1813         int this_mirror;
1814         int failed_mirror;
1815         int in_validation;
1816 };
1817
1818 static int free_io_failure(struct inode *inode, struct io_failure_record *rec,
1819                                 int did_repair)
1820 {
1821         int ret;
1822         int err = 0;
1823         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
1824
1825         set_state_private(failure_tree, rec->start, 0);
1826         ret = clear_extent_bits(failure_tree, rec->start,
1827                                 rec->start + rec->len - 1,
1828                                 EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
1829         if (ret)
1830                 err = ret;
1831
1832         if (did_repair) {
1833                 ret = clear_extent_bits(&BTRFS_I(inode)->io_tree, rec->start,
1834                                         rec->start + rec->len - 1,
1835                                         EXTENT_DAMAGED, GFP_NOFS);
1836                 if (ret && !err)
1837                         err = ret;
1838         }
1839
1840         kfree(rec);
1841         return err;
1842 }
1843
1844 static void repair_io_failure_callback(struct bio *bio, int err)
1845 {
1846         complete(bio->bi_private);
1847 }
1848
1849 /*
1850  * this bypasses the standard btrfs submit functions deliberately, as
1851  * the standard behavior is to write all copies in a raid setup. here we only
1852  * want to write the one bad copy. so we do the mapping for ourselves and issue
1853  * submit_bio directly.
1854  * to avoid any synchonization issues, wait for the data after writing, which
1855  * actually prevents the read that triggered the error from finishing.
1856  * currently, there can be no more than two copies of every data bit. thus,
1857  * exactly one rewrite is required.
1858  */
1859 int repair_io_failure(struct btrfs_mapping_tree *map_tree, u64 start,
1860                         u64 length, u64 logical, struct page *page,
1861                         int mirror_num)
1862 {
1863         struct bio *bio;
1864         struct btrfs_device *dev;
1865         DECLARE_COMPLETION_ONSTACK(compl);
1866         u64 map_length = 0;
1867         u64 sector;
1868         struct btrfs_bio *bbio = NULL;
1869         int ret;
1870
1871         BUG_ON(!mirror_num);
1872
1873         bio = bio_alloc(GFP_NOFS, 1);
1874         if (!bio)
1875                 return -EIO;
1876         bio->bi_private = &compl;
1877         bio->bi_end_io = repair_io_failure_callback;
1878         bio->bi_size = 0;
1879         map_length = length;
1880
1881         ret = btrfs_map_block(map_tree, WRITE, logical,
1882                               &map_length, &bbio, mirror_num);
1883         if (ret) {
1884                 bio_put(bio);
1885                 return -EIO;
1886         }
1887         BUG_ON(mirror_num != bbio->mirror_num);
1888         sector = bbio->stripes[mirror_num-1].physical >> 9;
1889         bio->bi_sector = sector;
1890         dev = bbio->stripes[mirror_num-1].dev;
1891         kfree(bbio);
1892         if (!dev || !dev->bdev || !dev->writeable) {
1893                 bio_put(bio);
1894                 return -EIO;
1895         }
1896         bio->bi_bdev = dev->bdev;
1897         bio_add_page(bio, page, length, start-page_offset(page));
1898         btrfsic_submit_bio(WRITE_SYNC, bio);
1899         wait_for_completion(&compl);
1900
1901         if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
1902                 /* try to remap that extent elsewhere? */
1903                 bio_put(bio);
1904                 return -EIO;
1905         }
1906
1907         printk(KERN_INFO "btrfs read error corrected: ino %lu off %llu (dev %s "
1908                         "sector %llu)\n", page->mapping->host->i_ino, start,
1909                         dev->name, sector);
1910
1911         bio_put(bio);
1912         return 0;
1913 }
1914
1915 /*
1916  * each time an IO finishes, we do a fast check in the IO failure tree
1917  * to see if we need to process or clean up an io_failure_record
1918  */
1919 static int clean_io_failure(u64 start, struct page *page)
1920 {
1921         u64 private;
1922         u64 private_failure;
1923         struct io_failure_record *failrec;
1924         struct btrfs_mapping_tree *map_tree;
1925         struct extent_state *state;
1926         int num_copies;
1927         int did_repair = 0;
1928         int ret;
1929         struct inode *inode = page->mapping->host;
1930
1931         private = 0;
1932         ret = count_range_bits(&BTRFS_I(inode)->io_failure_tree, &private,
1933                                 (u64)-1, 1, EXTENT_DIRTY, 0);
1934         if (!ret)
1935                 return 0;
1936
1937         ret = get_state_private(&BTRFS_I(inode)->io_failure_tree, start,
1938                                 &private_failure);
1939         if (ret)
1940                 return 0;
1941
1942         failrec = (struct io_failure_record *)(unsigned long) private_failure;
1943         BUG_ON(!failrec->this_mirror);
1944
1945         if (failrec->in_validation) {
1946                 /* there was no real error, just free the record */
1947                 pr_debug("clean_io_failure: freeing dummy error at %llu\n",
1948                          failrec->start);
1949                 did_repair = 1;
1950                 goto out;
1951         }
1952
1953         spin_lock(&BTRFS_I(inode)->io_tree.lock);
1954         state = find_first_extent_bit_state(&BTRFS_I(inode)->io_tree,
1955                                             failrec->start,
1956                                             EXTENT_LOCKED);
1957         spin_unlock(&BTRFS_I(inode)->io_tree.lock);
1958
1959         if (state && state->start == failrec->start) {
1960                 map_tree = &BTRFS_I(inode)->root->fs_info->mapping_tree;
1961                 num_copies = btrfs_num_copies(map_tree, failrec->logical,
1962                                                 failrec->len);
1963                 if (num_copies > 1)  {
1964                         ret = repair_io_failure(map_tree, start, failrec->len,
1965                                                 failrec->logical, page,
1966                                                 failrec->failed_mirror);
1967                         did_repair = !ret;
1968                 }
1969         }
1970
1971 out:
1972         if (!ret)
1973                 ret = free_io_failure(inode, failrec, did_repair);
1974
1975         return ret;
1976 }
1977
1978 /*
1979  * this is a generic handler for readpage errors (default
1980  * readpage_io_failed_hook). if other copies exist, read those and write back
1981  * good data to the failed position. does not investigate in remapping the
1982  * failed extent elsewhere, hoping the device will be smart enough to do this as
1983  * needed
1984  */
1985
1986 static int bio_readpage_error(struct bio *failed_bio, struct page *page,
1987                                 u64 start, u64 end, int failed_mirror,
1988                                 struct extent_state *state)
1989 {
1990         struct io_failure_record *failrec = NULL;
1991         u64 private;
1992         struct extent_map *em;
1993         struct inode *inode = page->mapping->host;
1994         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
1995         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
1996         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
1997         struct bio *bio;
1998         int num_copies;
1999         int ret;
2000         int read_mode;
2001         u64 logical;
2002
2003         BUG_ON(failed_bio->bi_rw & REQ_WRITE);
2004
2005         ret = get_state_private(failure_tree, start, &private);
2006         if (ret) {
2007                 failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
2008                 if (!failrec)
2009                         return -ENOMEM;
2010                 failrec->start = start;
2011                 failrec->len = end - start + 1;
2012                 failrec->this_mirror = 0;
2013                 failrec->bio_flags = 0;
2014                 failrec->in_validation = 0;
2015
2016                 read_lock(&em_tree->lock);
2017                 em = lookup_extent_mapping(em_tree, start, failrec->len);
2018                 if (!em) {
2019                         read_unlock(&em_tree->lock);
2020                         kfree(failrec);
2021                         return -EIO;
2022                 }
2023
2024                 if (em->start > start || em->start + em->len < start) {
2025                         free_extent_map(em);
2026                         em = NULL;
2027                 }
2028                 read_unlock(&em_tree->lock);
2029
2030                 if (!em || IS_ERR(em)) {
2031                         kfree(failrec);
2032                         return -EIO;
2033                 }
2034                 logical = start - em->start;
2035                 logical = em->block_start + logical;
2036                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2037                         logical = em->block_start;
2038                         failrec->bio_flags = EXTENT_BIO_COMPRESSED;
2039                         extent_set_compress_type(&failrec->bio_flags,
2040                                                  em->compress_type);
2041                 }
2042                 pr_debug("bio_readpage_error: (new) logical=%llu, start=%llu, "
2043                          "len=%llu\n", logical, start, failrec->len);
2044                 failrec->logical = logical;
2045                 free_extent_map(em);
2046
2047                 /* set the bits in the private failure tree */
2048                 ret = set_extent_bits(failure_tree, start, end,
2049                                         EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
2050                 if (ret >= 0)
2051                         ret = set_state_private(failure_tree, start,
2052                                                 (u64)(unsigned long)failrec);
2053                 /* set the bits in the inode's tree */
2054                 if (ret >= 0)
2055                         ret = set_extent_bits(tree, start, end, EXTENT_DAMAGED,
2056                                                 GFP_NOFS);
2057                 if (ret < 0) {
2058                         kfree(failrec);
2059                         return ret;
2060                 }
2061         } else {
2062                 failrec = (struct io_failure_record *)(unsigned long)private;
2063                 pr_debug("bio_readpage_error: (found) logical=%llu, "
2064                          "start=%llu, len=%llu, validation=%d\n",
2065                          failrec->logical, failrec->start, failrec->len,
2066                          failrec->in_validation);
2067                 /*
2068                  * when data can be on disk more than twice, add to failrec here
2069                  * (e.g. with a list for failed_mirror) to make
2070                  * clean_io_failure() clean all those errors at once.
2071                  */
2072         }
2073         num_copies = btrfs_num_copies(
2074                               &BTRFS_I(inode)->root->fs_info->mapping_tree,
2075                               failrec->logical, failrec->len);
2076         if (num_copies == 1) {
2077                 /*
2078                  * we only have a single copy of the data, so don't bother with
2079                  * all the retry and error correction code that follows. no
2080                  * matter what the error is, it is very likely to persist.
2081                  */
2082                 pr_debug("bio_readpage_error: cannot repair, num_copies == 1. "
2083                          "state=%p, num_copies=%d, next_mirror %d, "
2084                          "failed_mirror %d\n", state, num_copies,
2085                          failrec->this_mirror, failed_mirror);
2086                 free_io_failure(inode, failrec, 0);
2087                 return -EIO;
2088         }
2089
2090         if (!state) {
2091                 spin_lock(&tree->lock);
2092                 state = find_first_extent_bit_state(tree, failrec->start,
2093                                                     EXTENT_LOCKED);
2094                 if (state && state->start != failrec->start)
2095                         state = NULL;
2096                 spin_unlock(&tree->lock);
2097         }
2098
2099         /*
2100          * there are two premises:
2101          *      a) deliver good data to the caller
2102          *      b) correct the bad sectors on disk
2103          */
2104         if (failed_bio->bi_vcnt > 1) {
2105                 /*
2106                  * to fulfill b), we need to know the exact failing sectors, as
2107                  * we don't want to rewrite any more than the failed ones. thus,
2108                  * we need separate read requests for the failed bio
2109                  *
2110                  * if the following BUG_ON triggers, our validation request got
2111                  * merged. we need separate requests for our algorithm to work.
2112                  */
2113                 BUG_ON(failrec->in_validation);
2114                 failrec->in_validation = 1;
2115                 failrec->this_mirror = failed_mirror;
2116                 read_mode = READ_SYNC | REQ_FAILFAST_DEV;
2117         } else {
2118                 /*
2119                  * we're ready to fulfill a) and b) alongside. get a good copy
2120                  * of the failed sector and if we succeed, we have setup
2121                  * everything for repair_io_failure to do the rest for us.
2122                  */
2123                 if (failrec->in_validation) {
2124                         BUG_ON(failrec->this_mirror != failed_mirror);
2125                         failrec->in_validation = 0;
2126                         failrec->this_mirror = 0;
2127                 }
2128                 failrec->failed_mirror = failed_mirror;
2129                 failrec->this_mirror++;
2130                 if (failrec->this_mirror == failed_mirror)
2131                         failrec->this_mirror++;
2132                 read_mode = READ_SYNC;
2133         }
2134
2135         if (!state || failrec->this_mirror > num_copies) {
2136                 pr_debug("bio_readpage_error: (fail) state=%p, num_copies=%d, "
2137                          "next_mirror %d, failed_mirror %d\n", state,
2138                          num_copies, failrec->this_mirror, failed_mirror);
2139                 free_io_failure(inode, failrec, 0);
2140                 return -EIO;
2141         }
2142
2143         bio = bio_alloc(GFP_NOFS, 1);
2144         bio->bi_private = state;
2145         bio->bi_end_io = failed_bio->bi_end_io;
2146         bio->bi_sector = failrec->logical >> 9;
2147         bio->bi_bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
2148         bio->bi_size = 0;
2149
2150         bio_add_page(bio, page, failrec->len, start - page_offset(page));
2151
2152         pr_debug("bio_readpage_error: submitting new read[%#x] to "
2153                  "this_mirror=%d, num_copies=%d, in_validation=%d\n", read_mode,
2154                  failrec->this_mirror, num_copies, failrec->in_validation);
2155
2156         ret = tree->ops->submit_bio_hook(inode, read_mode, bio,
2157                                          failrec->this_mirror,
2158                                          failrec->bio_flags, 0);
2159         return ret;
2160 }
2161
2162 /* lots and lots of room for performance fixes in the end_bio funcs */
2163
2164 int end_extent_writepage(struct page *page, int err, u64 start, u64 end)
2165 {
2166         int uptodate = (err == 0);
2167         struct extent_io_tree *tree;
2168         int ret;
2169
2170         tree = &BTRFS_I(page->mapping->host)->io_tree;
2171
2172         if (tree->ops && tree->ops->writepage_end_io_hook) {
2173                 ret = tree->ops->writepage_end_io_hook(page, start,
2174                                                end, NULL, uptodate);
2175                 if (ret)
2176                         uptodate = 0;
2177         }
2178
2179         if (!uptodate && tree->ops &&
2180             tree->ops->writepage_io_failed_hook) {
2181                 ret = tree->ops->writepage_io_failed_hook(NULL, page,
2182                                                  start, end, NULL);
2183                 /* Writeback already completed */
2184                 if (ret == 0)
2185                         return 1;
2186         }
2187
2188         if (!uptodate) {
2189                 clear_extent_uptodate(tree, start, end, NULL, GFP_NOFS);
2190                 ClearPageUptodate(page);
2191                 SetPageError(page);
2192         }
2193         return 0;
2194 }
2195
2196 /*
2197  * after a writepage IO is done, we need to:
2198  * clear the uptodate bits on error
2199  * clear the writeback bits in the extent tree for this IO
2200  * end_page_writeback if the page has no more pending IO
2201  *
2202  * Scheduling is not allowed, so the extent state tree is expected
2203  * to have one and only one object corresponding to this IO.
2204  */
2205 static void end_bio_extent_writepage(struct bio *bio, int err)
2206 {
2207         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
2208         struct extent_io_tree *tree;
2209         u64 start;
2210         u64 end;
2211         int whole_page;
2212
2213         do {
2214                 struct page *page = bvec->bv_page;
2215                 tree = &BTRFS_I(page->mapping->host)->io_tree;
2216
2217                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
2218                          bvec->bv_offset;
2219                 end = start + bvec->bv_len - 1;
2220
2221                 if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
2222                         whole_page = 1;
2223                 else
2224                         whole_page = 0;
2225
2226                 if (--bvec >= bio->bi_io_vec)
2227                         prefetchw(&bvec->bv_page->flags);
2228
2229                 if (end_extent_writepage(page, err, start, end))
2230                         continue;
2231
2232                 if (whole_page)
2233                         end_page_writeback(page);
2234                 else
2235                         check_page_writeback(tree, page);
2236         } while (bvec >= bio->bi_io_vec);
2237
2238         bio_put(bio);
2239 }
2240
2241 /*
2242  * after a readpage IO is done, we need to:
2243  * clear the uptodate bits on error
2244  * set the uptodate bits if things worked
2245  * set the page up to date if all extents in the tree are uptodate
2246  * clear the lock bit in the extent tree
2247  * unlock the page if there are no other extents locked for it
2248  *
2249  * Scheduling is not allowed, so the extent state tree is expected
2250  * to have one and only one object corresponding to this IO.
2251  */
2252 static void end_bio_extent_readpage(struct bio *bio, int err)
2253 {
2254         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
2255         struct bio_vec *bvec_end = bio->bi_io_vec + bio->bi_vcnt - 1;
2256         struct bio_vec *bvec = bio->bi_io_vec;
2257         struct extent_io_tree *tree;
2258         u64 start;
2259         u64 end;
2260         int whole_page;
2261         int ret;
2262
2263         if (err)
2264                 uptodate = 0;
2265
2266         do {
2267                 struct page *page = bvec->bv_page;
2268                 struct extent_state *cached = NULL;
2269                 struct extent_state *state;
2270
2271                 pr_debug("end_bio_extent_readpage: bi_vcnt=%d, idx=%d, err=%d, "
2272                          "mirror=%ld\n", bio->bi_vcnt, bio->bi_idx, err,
2273                          (long int)bio->bi_bdev);
2274                 tree = &BTRFS_I(page->mapping->host)->io_tree;
2275
2276                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
2277                         bvec->bv_offset;
2278                 end = start + bvec->bv_len - 1;
2279
2280                 if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
2281                         whole_page = 1;
2282                 else
2283                         whole_page = 0;
2284
2285                 if (++bvec <= bvec_end)
2286                         prefetchw(&bvec->bv_page->flags);
2287
2288                 spin_lock(&tree->lock);
2289                 state = find_first_extent_bit_state(tree, start, EXTENT_LOCKED);
2290                 if (state && state->start == start) {
2291                         /*
2292                          * take a reference on the state, unlock will drop
2293                          * the ref
2294                          */
2295                         cache_state(state, &cached);
2296                 }
2297                 spin_unlock(&tree->lock);
2298
2299                 if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
2300                         ret = tree->ops->readpage_end_io_hook(page, start, end,
2301                                                               state);
2302                         if (ret)
2303                                 uptodate = 0;
2304                         else
2305                                 clean_io_failure(start, page);
2306                 }
2307                 if (!uptodate) {
2308                         int failed_mirror;
2309                         failed_mirror = (int)(unsigned long)bio->bi_bdev;
2310                         /*
2311                          * The generic bio_readpage_error handles errors the
2312                          * following way: If possible, new read requests are
2313                          * created and submitted and will end up in
2314                          * end_bio_extent_readpage as well (if we're lucky, not
2315                          * in the !uptodate case). In that case it returns 0 and
2316                          * we just go on with the next page in our bio. If it
2317                          * can't handle the error it will return -EIO and we
2318                          * remain responsible for that page.
2319                          */
2320                         ret = bio_readpage_error(bio, page, start, end,
2321                                                         failed_mirror, NULL);
2322                         if (ret == 0) {
2323 error_handled:
2324                                 uptodate =
2325                                         test_bit(BIO_UPTODATE, &bio->bi_flags);
2326                                 if (err)
2327                                         uptodate = 0;
2328                                 uncache_state(&cached);
2329                                 continue;
2330                         }
2331                         if (tree->ops && tree->ops->readpage_io_failed_hook) {
2332                                 ret = tree->ops->readpage_io_failed_hook(
2333                                                         bio, page, start, end,
2334                                                         failed_mirror, state);
2335                                 if (ret == 0)
2336                                         goto error_handled;
2337                         }
2338                 }
2339
2340                 if (uptodate) {
2341                         set_extent_uptodate(tree, start, end, &cached,
2342                                             GFP_ATOMIC);
2343                 }
2344                 unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
2345
2346                 if (whole_page) {
2347                         if (uptodate) {
2348                                 SetPageUptodate(page);
2349                         } else {
2350                                 ClearPageUptodate(page);
2351                                 SetPageError(page);
2352                         }
2353                         unlock_page(page);
2354                 } else {
2355                         if (uptodate) {
2356                                 check_page_uptodate(tree, page);
2357                         } else {
2358                                 ClearPageUptodate(page);
2359                                 SetPageError(page);
2360                         }
2361                         check_page_locked(tree, page);
2362                 }
2363         } while (bvec <= bvec_end);
2364
2365         bio_put(bio);
2366 }
2367
2368 struct bio *
2369 btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
2370                 gfp_t gfp_flags)
2371 {
2372         struct bio *bio;
2373
2374         bio = bio_alloc(gfp_flags, nr_vecs);
2375
2376         if (bio == NULL && (current->flags & PF_MEMALLOC)) {
2377                 while (!bio && (nr_vecs /= 2))
2378                         bio = bio_alloc(gfp_flags, nr_vecs);
2379         }
2380
2381         if (bio) {
2382                 bio->bi_size = 0;
2383                 bio->bi_bdev = bdev;
2384                 bio->bi_sector = first_sector;
2385         }
2386         return bio;
2387 }
2388
2389 static int submit_one_bio(int rw, struct bio *bio, int mirror_num,
2390                           unsigned long bio_flags)
2391 {
2392         int ret = 0;
2393         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
2394         struct page *page = bvec->bv_page;
2395         struct extent_io_tree *tree = bio->bi_private;
2396         u64 start;
2397
2398         start = ((u64)page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset;
2399
2400         bio->bi_private = NULL;
2401
2402         bio_get(bio);
2403
2404         if (tree->ops && tree->ops->submit_bio_hook)
2405                 ret = tree->ops->submit_bio_hook(page->mapping->host, rw, bio,
2406                                            mirror_num, bio_flags, start);
2407         else
2408                 btrfsic_submit_bio(rw, bio);
2409
2410         if (bio_flagged(bio, BIO_EOPNOTSUPP))
2411                 ret = -EOPNOTSUPP;
2412         bio_put(bio);
2413         return ret;
2414 }
2415
2416 static int submit_extent_page(int rw, struct extent_io_tree *tree,
2417                               struct page *page, sector_t sector,
2418                               size_t size, unsigned long offset,
2419                               struct block_device *bdev,
2420                               struct bio **bio_ret,
2421                               unsigned long max_pages,
2422                               bio_end_io_t end_io_func,
2423                               int mirror_num,
2424                               unsigned long prev_bio_flags,
2425                               unsigned long bio_flags)
2426 {
2427         int ret = 0;
2428         struct bio *bio;
2429         int nr;
2430         int contig = 0;
2431         int this_compressed = bio_flags & EXTENT_BIO_COMPRESSED;
2432         int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
2433         size_t page_size = min_t(size_t, size, PAGE_CACHE_SIZE);
2434
2435         if (bio_ret && *bio_ret) {
2436                 bio = *bio_ret;
2437                 if (old_compressed)
2438                         contig = bio->bi_sector == sector;
2439                 else
2440                         contig = bio->bi_sector + (bio->bi_size >> 9) ==
2441                                 sector;
2442
2443                 if (prev_bio_flags != bio_flags || !contig ||
2444                     (tree->ops && tree->ops->merge_bio_hook &&
2445                      tree->ops->merge_bio_hook(page, offset, page_size, bio,
2446                                                bio_flags)) ||
2447                     bio_add_page(bio, page, page_size, offset) < page_size) {
2448                         ret = submit_one_bio(rw, bio, mirror_num,
2449                                              prev_bio_flags);
2450                         bio = NULL;
2451                 } else {
2452                         return 0;
2453                 }
2454         }
2455         if (this_compressed)
2456                 nr = BIO_MAX_PAGES;
2457         else
2458                 nr = bio_get_nr_vecs(bdev);
2459
2460         bio = btrfs_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
2461         if (!bio)
2462                 return -ENOMEM;
2463
2464         bio_add_page(bio, page, page_size, offset);
2465         bio->bi_end_io = end_io_func;
2466         bio->bi_private = tree;
2467
2468         if (bio_ret)
2469                 *bio_ret = bio;
2470         else
2471                 ret = submit_one_bio(rw, bio, mirror_num, bio_flags);
2472
2473         return ret;
2474 }
2475
2476 void set_page_extent_mapped(struct page *page)
2477 {
2478         if (!PagePrivate(page)) {
2479                 SetPagePrivate(page);
2480                 page_cache_get(page);
2481                 set_page_private(page, EXTENT_PAGE_PRIVATE);
2482         }
2483 }
2484
2485 static void set_page_extent_head(struct page *page, unsigned long len)
2486 {
2487         WARN_ON(!PagePrivate(page));
2488         set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2);
2489 }
2490
2491 /*
2492  * basic readpage implementation.  Locked extent state structs are inserted
2493  * into the tree that are removed when the IO is done (by the end_io
2494  * handlers)
2495  */
2496 static int __extent_read_full_page(struct extent_io_tree *tree,
2497                                    struct page *page,
2498                                    get_extent_t *get_extent,
2499                                    struct bio **bio, int mirror_num,
2500                                    unsigned long *bio_flags)
2501 {
2502         struct inode *inode = page->mapping->host;
2503         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2504         u64 page_end = start + PAGE_CACHE_SIZE - 1;
2505         u64 end;
2506         u64 cur = start;
2507         u64 extent_offset;
2508         u64 last_byte = i_size_read(inode);
2509         u64 block_start;
2510         u64 cur_end;
2511         sector_t sector;
2512         struct extent_map *em;
2513         struct block_device *bdev;
2514         struct btrfs_ordered_extent *ordered;
2515         int ret;
2516         int nr = 0;
2517         size_t pg_offset = 0;
2518         size_t iosize;
2519         size_t disk_io_size;
2520         size_t blocksize = inode->i_sb->s_blocksize;
2521         unsigned long this_bio_flag = 0;
2522
2523         set_page_extent_mapped(page);
2524
2525         if (!PageUptodate(page)) {
2526                 if (cleancache_get_page(page) == 0) {
2527                         BUG_ON(blocksize != PAGE_SIZE);
2528                         goto out;
2529                 }
2530         }
2531
2532         end = page_end;
2533         while (1) {
2534                 lock_extent(tree, start, end, GFP_NOFS);
2535                 ordered = btrfs_lookup_ordered_extent(inode, start);
2536                 if (!ordered)
2537                         break;
2538                 unlock_extent(tree, start, end, GFP_NOFS);
2539                 btrfs_start_ordered_extent(inode, ordered, 1);
2540                 btrfs_put_ordered_extent(ordered);
2541         }
2542
2543         if (page->index == last_byte >> PAGE_CACHE_SHIFT) {
2544                 char *userpage;
2545                 size_t zero_offset = last_byte & (PAGE_CACHE_SIZE - 1);
2546
2547                 if (zero_offset) {
2548                         iosize = PAGE_CACHE_SIZE - zero_offset;
2549                         userpage = kmap_atomic(page);
2550                         memset(userpage + zero_offset, 0, iosize);
2551                         flush_dcache_page(page);
2552                         kunmap_atomic(userpage);
2553                 }
2554         }
2555         while (cur <= end) {
2556                 if (cur >= last_byte) {
2557                         char *userpage;
2558                         struct extent_state *cached = NULL;
2559
2560                         iosize = PAGE_CACHE_SIZE - pg_offset;
2561                         userpage = kmap_atomic(page);
2562                         memset(userpage + pg_offset, 0, iosize);
2563                         flush_dcache_page(page);
2564                         kunmap_atomic(userpage);
2565                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2566                                             &cached, GFP_NOFS);
2567                         unlock_extent_cached(tree, cur, cur + iosize - 1,
2568                                              &cached, GFP_NOFS);
2569                         break;
2570                 }
2571                 em = get_extent(inode, page, pg_offset, cur,
2572                                 end - cur + 1, 0);
2573                 if (IS_ERR_OR_NULL(em)) {
2574                         SetPageError(page);
2575                         unlock_extent(tree, cur, end, GFP_NOFS);
2576                         break;
2577                 }
2578                 extent_offset = cur - em->start;
2579                 BUG_ON(extent_map_end(em) <= cur);
2580                 BUG_ON(end < cur);
2581
2582                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2583                         this_bio_flag = EXTENT_BIO_COMPRESSED;
2584                         extent_set_compress_type(&this_bio_flag,
2585                                                  em->compress_type);
2586                 }
2587
2588                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2589                 cur_end = min(extent_map_end(em) - 1, end);
2590                 iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
2591                 if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
2592                         disk_io_size = em->block_len;
2593                         sector = em->block_start >> 9;
2594                 } else {
2595                         sector = (em->block_start + extent_offset) >> 9;
2596                         disk_io_size = iosize;
2597                 }
2598                 bdev = em->bdev;
2599                 block_start = em->block_start;
2600                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
2601                         block_start = EXTENT_MAP_HOLE;
2602                 free_extent_map(em);
2603                 em = NULL;
2604
2605                 /* we've found a hole, just zero and go on */
2606                 if (block_start == EXTENT_MAP_HOLE) {
2607                         char *userpage;
2608                         struct extent_state *cached = NULL;
2609
2610                         userpage = kmap_atomic(page);
2611                         memset(userpage + pg_offset, 0, iosize);
2612                         flush_dcache_page(page);
2613                         kunmap_atomic(userpage);
2614
2615                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2616                                             &cached, GFP_NOFS);
2617                         unlock_extent_cached(tree, cur, cur + iosize - 1,
2618                                              &cached, GFP_NOFS);
2619                         cur = cur + iosize;
2620                         pg_offset += iosize;
2621                         continue;
2622                 }
2623                 /* the get_extent function already copied into the page */
2624                 if (test_range_bit(tree, cur, cur_end,
2625                                    EXTENT_UPTODATE, 1, NULL)) {
2626                         check_page_uptodate(tree, page);
2627                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2628                         cur = cur + iosize;
2629                         pg_offset += iosize;
2630                         continue;
2631                 }
2632                 /* we have an inline extent but it didn't get marked up
2633                  * to date.  Error out
2634                  */
2635                 if (block_start == EXTENT_MAP_INLINE) {
2636                         SetPageError(page);
2637                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2638                         cur = cur + iosize;
2639                         pg_offset += iosize;
2640                         continue;
2641                 }
2642
2643                 ret = 0;
2644                 if (tree->ops && tree->ops->readpage_io_hook) {
2645                         ret = tree->ops->readpage_io_hook(page, cur,
2646                                                           cur + iosize - 1);
2647                 }
2648                 if (!ret) {
2649                         unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
2650                         pnr -= page->index;
2651                         ret = submit_extent_page(READ, tree, page,
2652                                          sector, disk_io_size, pg_offset,
2653                                          bdev, bio, pnr,
2654                                          end_bio_extent_readpage, mirror_num,
2655                                          *bio_flags,
2656                                          this_bio_flag);
2657                         nr++;
2658                         *bio_flags = this_bio_flag;
2659                 }
2660                 if (ret)
2661                         SetPageError(page);
2662                 cur = cur + iosize;
2663                 pg_offset += iosize;
2664         }
2665 out:
2666         if (!nr) {
2667                 if (!PageError(page))
2668                         SetPageUptodate(page);
2669                 unlock_page(page);
2670         }
2671         return 0;
2672 }
2673
2674 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
2675                             get_extent_t *get_extent, int mirror_num)
2676 {
2677         struct bio *bio = NULL;
2678         unsigned long bio_flags = 0;
2679         int ret;
2680
2681         ret = __extent_read_full_page(tree, page, get_extent, &bio, mirror_num,
2682                                       &bio_flags);
2683         if (bio)
2684                 ret = submit_one_bio(READ, bio, mirror_num, bio_flags);
2685         return ret;
2686 }
2687
2688 static noinline void update_nr_written(struct page *page,
2689                                       struct writeback_control *wbc,
2690                                       unsigned long nr_written)
2691 {
2692         wbc->nr_to_write -= nr_written;
2693         if (wbc->range_cyclic || (wbc->nr_to_write > 0 &&
2694             wbc->range_start == 0 && wbc->range_end == LLONG_MAX))
2695                 page->mapping->writeback_index = page->index + nr_written;
2696 }
2697
2698 /*
2699  * the writepage semantics are similar to regular writepage.  extent
2700  * records are inserted to lock ranges in the tree, and as dirty areas
2701  * are found, they are marked writeback.  Then the lock bits are removed
2702  * and the end_io handler clears the writeback ranges
2703  */
2704 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
2705                               void *data)
2706 {
2707         struct inode *inode = page->mapping->host;
2708         struct extent_page_data *epd = data;
2709         struct extent_io_tree *tree = epd->tree;
2710         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2711         u64 delalloc_start;
2712         u64 page_end = start + PAGE_CACHE_SIZE - 1;
2713         u64 end;
2714         u64 cur = start;
2715         u64 extent_offset;
2716         u64 last_byte = i_size_read(inode);
2717         u64 block_start;
2718         u64 iosize;
2719         sector_t sector;
2720         struct extent_state *cached_state = NULL;
2721         struct extent_map *em;
2722         struct block_device *bdev;
2723         int ret;
2724         int nr = 0;
2725         size_t pg_offset = 0;
2726         size_t blocksize;
2727         loff_t i_size = i_size_read(inode);
2728         unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
2729         u64 nr_delalloc;
2730         u64 delalloc_end;
2731         int page_started;
2732         int compressed;
2733         int write_flags;
2734         unsigned long nr_written = 0;
2735         bool fill_delalloc = true;
2736
2737         if (wbc->sync_mode == WB_SYNC_ALL)
2738                 write_flags = WRITE_SYNC;
2739         else
2740                 write_flags = WRITE;
2741
2742         trace___extent_writepage(page, inode, wbc);
2743
2744         WARN_ON(!PageLocked(page));
2745
2746         ClearPageError(page);
2747
2748         pg_offset = i_size & (PAGE_CACHE_SIZE - 1);
2749         if (page->index > end_index ||
2750            (page->index == end_index && !pg_offset)) {
2751                 page->mapping->a_ops->invalidatepage(page, 0);
2752                 unlock_page(page);
2753                 return 0;
2754         }
2755
2756         if (page->index == end_index) {
2757                 char *userpage;
2758
2759                 userpage = kmap_atomic(page);
2760                 memset(userpage + pg_offset, 0,
2761                        PAGE_CACHE_SIZE - pg_offset);
2762                 kunmap_atomic(userpage);
2763                 flush_dcache_page(page);
2764         }
2765         pg_offset = 0;
2766
2767         set_page_extent_mapped(page);
2768
2769         if (!tree->ops || !tree->ops->fill_delalloc)
2770                 fill_delalloc = false;
2771
2772         delalloc_start = start;
2773         delalloc_end = 0;
2774         page_started = 0;
2775         if (!epd->extent_locked && fill_delalloc) {
2776                 u64 delalloc_to_write = 0;
2777                 /*
2778                  * make sure the wbc mapping index is at least updated
2779                  * to this page.
2780                  */
2781                 update_nr_written(page, wbc, 0);
2782
2783                 while (delalloc_end < page_end) {
2784                         nr_delalloc = find_lock_delalloc_range(inode, tree,
2785                                                        page,
2786                                                        &delalloc_start,
2787                                                        &delalloc_end,
2788                                                        128 * 1024 * 1024);
2789                         if (nr_delalloc == 0) {
2790                                 delalloc_start = delalloc_end + 1;
2791                                 continue;
2792                         }
2793                         ret = tree->ops->fill_delalloc(inode, page,
2794                                                        delalloc_start,
2795                                                        delalloc_end,
2796                                                        &page_started,
2797                                                        &nr_written);
2798                         BUG_ON(ret);
2799                         /*
2800                          * delalloc_end is already one less than the total
2801                          * length, so we don't subtract one from
2802                          * PAGE_CACHE_SIZE
2803                          */
2804                         delalloc_to_write += (delalloc_end - delalloc_start +
2805                                               PAGE_CACHE_SIZE) >>
2806                                               PAGE_CACHE_SHIFT;
2807                         delalloc_start = delalloc_end + 1;
2808                 }
2809                 if (wbc->nr_to_write < delalloc_to_write) {
2810                         int thresh = 8192;
2811
2812                         if (delalloc_to_write < thresh * 2)
2813                                 thresh = delalloc_to_write;
2814                         wbc->nr_to_write = min_t(u64, delalloc_to_write,
2815                                                  thresh);
2816                 }
2817
2818                 /* did the fill delalloc function already unlock and start
2819                  * the IO?
2820                  */
2821                 if (page_started) {
2822                         ret = 0;
2823                         /*
2824                          * we've unlocked the page, so we can't update
2825                          * the mapping's writeback index, just update
2826                          * nr_to_write.
2827                          */
2828                         wbc->nr_to_write -= nr_written;
2829                         goto done_unlocked;
2830                 }
2831         }
2832         if (tree->ops && tree->ops->writepage_start_hook) {
2833                 ret = tree->ops->writepage_start_hook(page, start,
2834                                                       page_end);
2835                 if (ret) {
2836                         /* Fixup worker will requeue */
2837                         if (ret == -EBUSY)
2838                                 wbc->pages_skipped++;
2839                         else
2840                                 redirty_page_for_writepage(wbc, page);
2841                         update_nr_written(page, wbc, nr_written);
2842                         unlock_page(page);
2843                         ret = 0;
2844                         goto done_unlocked;
2845                 }
2846         }
2847
2848         /*
2849          * we don't want to touch the inode after unlocking the page,
2850          * so we update the mapping writeback index now
2851          */
2852         update_nr_written(page, wbc, nr_written + 1);
2853
2854         end = page_end;
2855         if (last_byte <= start) {
2856                 if (tree->ops && tree->ops->writepage_end_io_hook)
2857                         tree->ops->writepage_end_io_hook(page, start,
2858                                                          page_end, NULL, 1);
2859                 goto done;
2860         }
2861
2862         blocksize = inode->i_sb->s_blocksize;
2863
2864         while (cur <= end) {
2865                 if (cur >= last_byte) {
2866                         if (tree->ops && tree->ops->writepage_end_io_hook)
2867                                 tree->ops->writepage_end_io_hook(page, cur,
2868                                                          page_end, NULL, 1);
2869                         break;
2870                 }
2871                 em = epd->get_extent(inode, page, pg_offset, cur,
2872                                      end - cur + 1, 1);
2873                 if (IS_ERR_OR_NULL(em)) {
2874                         SetPageError(page);
2875                         break;
2876                 }
2877
2878                 extent_offset = cur - em->start;
2879                 BUG_ON(extent_map_end(em) <= cur);
2880                 BUG_ON(end < cur);
2881                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2882                 iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
2883                 sector = (em->block_start + extent_offset) >> 9;
2884                 bdev = em->bdev;
2885                 block_start = em->block_start;
2886                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
2887                 free_extent_map(em);
2888                 em = NULL;
2889
2890                 /*
2891                  * compressed and inline extents are written through other
2892                  * paths in the FS
2893                  */
2894                 if (compressed || block_start == EXTENT_MAP_HOLE ||
2895                     block_start == EXTENT_MAP_INLINE) {
2896                         /*
2897                          * end_io notification does not happen here for
2898                          * compressed extents
2899                          */
2900                         if (!compressed && tree->ops &&
2901                             tree->ops->writepage_end_io_hook)
2902                                 tree->ops->writepage_end_io_hook(page, cur,
2903                                                          cur + iosize - 1,
2904                                                          NULL, 1);
2905                         else if (compressed) {
2906                                 /* we don't want to end_page_writeback on
2907                                  * a compressed extent.  this happens
2908                                  * elsewhere
2909                                  */
2910                                 nr++;
2911                         }
2912
2913                         cur += iosize;
2914                         pg_offset += iosize;
2915                         continue;
2916                 }
2917                 /* leave this out until we have a page_mkwrite call */
2918                 if (0 && !test_range_bit(tree, cur, cur + iosize - 1,
2919                                    EXTENT_DIRTY, 0, NULL)) {
2920                         cur = cur + iosize;
2921                         pg_offset += iosize;
2922                         continue;
2923                 }
2924
2925                 if (tree->ops && tree->ops->writepage_io_hook) {
2926                         ret = tree->ops->writepage_io_hook(page, cur,
2927                                                 cur + iosize - 1);
2928                 } else {
2929                         ret = 0;
2930                 }
2931                 if (ret) {
2932                         SetPageError(page);
2933                 } else {
2934                         unsigned long max_nr = end_index + 1;
2935
2936                         set_range_writeback(tree, cur, cur + iosize - 1);
2937                         if (!PageWriteback(page)) {
2938                                 printk(KERN_ERR "btrfs warning page %lu not "
2939                                        "writeback, cur %llu end %llu\n",
2940                                        page->index, (unsigned long long)cur,
2941                                        (unsigned long long)end);
2942                         }
2943
2944                         ret = submit_extent_page(write_flags, tree, page,
2945                                                  sector, iosize, pg_offset,
2946                                                  bdev, &epd->bio, max_nr,
2947                                                  end_bio_extent_writepage,
2948                                                  0, 0, 0);
2949                         if (ret)
2950                                 SetPageError(page);
2951                 }
2952                 cur = cur + iosize;
2953                 pg_offset += iosize;
2954                 nr++;
2955         }
2956 done:
2957         if (nr == 0) {
2958                 /* make sure the mapping tag for page dirty gets cleared */
2959                 set_page_writeback(page);
2960                 end_page_writeback(page);
2961         }
2962         unlock_page(page);
2963
2964 done_unlocked:
2965
2966         /* drop our reference on any cached states */
2967         free_extent_state(cached_state);
2968         return 0;
2969 }
2970
2971 /**
2972  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
2973  * @mapping: address space structure to write
2974  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
2975  * @writepage: function called for each page
2976  * @data: data passed to writepage function
2977  *
2978  * If a page is already under I/O, write_cache_pages() skips it, even
2979  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
2980  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
2981  * and msync() need to guarantee that all the data which was dirty at the time
2982  * the call was made get new I/O started against them.  If wbc->sync_mode is
2983  * WB_SYNC_ALL then we were called for data integrity and we must wait for
2984  * existing IO to complete.
2985  */
2986 static int extent_write_cache_pages(struct extent_io_tree *tree,
2987                              struct address_space *mapping,
2988                              struct writeback_control *wbc,
2989                              writepage_t writepage, void *data,
2990                              void (*flush_fn)(void *))
2991 {
2992         int ret = 0;
2993         int done = 0;
2994         int nr_to_write_done = 0;
2995         struct pagevec pvec;
2996         int nr_pages;
2997         pgoff_t index;
2998         pgoff_t end;            /* Inclusive */
2999         int scanned = 0;
3000         int tag;
3001
3002         pagevec_init(&pvec, 0);
3003         if (wbc->range_cyclic) {
3004                 index = mapping->writeback_index; /* Start from prev offset */
3005                 end = -1;
3006         } else {
3007                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
3008                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
3009                 scanned = 1;
3010         }
3011         if (wbc->sync_mode == WB_SYNC_ALL)
3012                 tag = PAGECACHE_TAG_TOWRITE;
3013         else
3014                 tag = PAGECACHE_TAG_DIRTY;
3015 retry:
3016         if (wbc->sync_mode == WB_SYNC_ALL)
3017                 tag_pages_for_writeback(mapping, index, end);
3018         while (!done && !nr_to_write_done && (index <= end) &&
3019                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3020                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3021                 unsigned i;
3022
3023                 scanned = 1;
3024                 for (i = 0; i < nr_pages; i++) {
3025                         struct page *page = pvec.pages[i];
3026
3027                         /*
3028                          * At this point we hold neither mapping->tree_lock nor
3029                          * lock on the page itself: the page may be truncated or
3030                          * invalidated (changing page->mapping to NULL), or even
3031                          * swizzled back from swapper_space to tmpfs file
3032                          * mapping
3033                          */
3034                         if (tree->ops &&
3035                             tree->ops->write_cache_pages_lock_hook) {
3036                                 tree->ops->write_cache_pages_lock_hook(page,
3037                                                                data, flush_fn);
3038                         } else {
3039                                 if (!trylock_page(page)) {
3040                                         flush_fn(data);
3041                                         lock_page(page);
3042                                 }
3043                         }
3044
3045                         if (unlikely(page->mapping != mapping)) {
3046                                 unlock_page(page);
3047                                 continue;
3048                         }
3049
3050                         if (!wbc->range_cyclic && page->index > end) {
3051                                 done = 1;
3052                                 unlock_page(page);
3053                                 continue;
3054                         }
3055
3056                         if (wbc->sync_mode != WB_SYNC_NONE) {
3057                                 if (PageWriteback(page))
3058                                         flush_fn(data);
3059                                 wait_on_page_writeback(page);
3060                         }
3061
3062                         if (PageWriteback(page) ||
3063                             !clear_page_dirty_for_io(page)) {
3064                                 unlock_page(page);
3065                                 continue;
3066                         }
3067
3068                         ret = (*writepage)(page, wbc, data);
3069
3070                         if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
3071                                 unlock_page(page);
3072                                 ret = 0;
3073                         }
3074                         if (ret)
3075                                 done = 1;
3076
3077                         /*
3078                          * the filesystem may choose to bump up nr_to_write.
3079                          * We have to make sure to honor the new nr_to_write
3080                          * at any time
3081                          */
3082                         nr_to_write_done = wbc->nr_to_write <= 0;
3083                 }
3084                 pagevec_release(&pvec);
3085                 cond_resched();
3086         }
3087         if (!scanned && !done) {
3088                 /*
3089                  * We hit the last page and there is more work to be done: wrap
3090                  * back to the start of the file
3091                  */
3092                 scanned = 1;
3093                 index = 0;
3094                 goto retry;
3095         }
3096         return ret;
3097 }
3098
3099 static void flush_epd_write_bio(struct extent_page_data *epd)
3100 {
3101         if (epd->bio) {
3102                 if (epd->sync_io)
3103                         submit_one_bio(WRITE_SYNC, epd->bio, 0, 0);
3104                 else
3105                         submit_one_bio(WRITE, epd->bio, 0, 0);
3106                 epd->bio = NULL;
3107         }
3108 }
3109
3110 static noinline void flush_write_bio(void *data)
3111 {
3112         struct extent_page_data *epd = data;
3113         flush_epd_write_bio(epd);
3114 }
3115
3116 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
3117                           get_extent_t *get_extent,
3118                           struct writeback_control *wbc)
3119 {
3120         int ret;
3121         struct extent_page_data epd = {
3122                 .bio = NULL,
3123                 .tree = tree,
3124                 .get_extent = get_extent,
3125                 .extent_locked = 0,
3126                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
3127         };
3128
3129         ret = __extent_writepage(page, wbc, &epd);
3130
3131         flush_epd_write_bio(&epd);
3132         return ret;
3133 }
3134
3135 int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
3136                               u64 start, u64 end, get_extent_t *get_extent,
3137                               int mode)
3138 {
3139         int ret = 0;
3140         struct address_space *mapping = inode->i_mapping;
3141         struct page *page;
3142         unsigned long nr_pages = (end - start + PAGE_CACHE_SIZE) >>
3143                 PAGE_CACHE_SHIFT;
3144
3145         struct extent_page_data epd = {
3146                 .bio = NULL,
3147                 .tree = tree,
3148                 .get_extent = get_extent,
3149                 .extent_locked = 1,
3150                 .sync_io = mode == WB_SYNC_ALL,
3151         };
3152         struct writeback_control wbc_writepages = {
3153                 .sync_mode      = mode,
3154                 .nr_to_write    = nr_pages * 2,
3155                 .range_start    = start,
3156                 .range_end      = end + 1,
3157         };
3158
3159         while (start <= end) {
3160                 page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
3161                 if (clear_page_dirty_for_io(page))
3162                         ret = __extent_writepage(page, &wbc_writepages, &epd);
3163                 else {
3164                         if (tree->ops && tree->ops->writepage_end_io_hook)
3165                                 tree->ops->writepage_end_io_hook(page, start,
3166                                                  start + PAGE_CACHE_SIZE - 1,
3167                                                  NULL, 1);
3168                         unlock_page(page);
3169                 }
3170                 page_cache_release(page);
3171                 start += PAGE_CACHE_SIZE;
3172         }
3173
3174         flush_epd_write_bio(&epd);
3175         return ret;
3176 }
3177
3178 int extent_writepages(struct extent_io_tree *tree,
3179                       struct address_space *mapping,
3180                       get_extent_t *get_extent,
3181                       struct writeback_control *wbc)
3182 {
3183         int ret = 0;
3184         struct extent_page_data epd = {
3185                 .bio = NULL,
3186                 .tree = tree,
3187                 .get_extent = get_extent,
3188                 .extent_locked = 0,
3189                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
3190         };
3191
3192         ret = extent_write_cache_pages(tree, mapping, wbc,
3193                                        __extent_writepage, &epd,
3194                                        flush_write_bio);
3195         flush_epd_write_bio(&epd);
3196         return ret;
3197 }
3198
3199 int extent_readpages(struct extent_io_tree *tree,
3200                      struct address_space *mapping,
3201                      struct list_head *pages, unsigned nr_pages,
3202                      get_extent_t get_extent)
3203 {
3204         struct bio *bio = NULL;
3205         unsigned page_idx;
3206         unsigned long bio_flags = 0;
3207
3208         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
3209                 struct page *page = list_entry(pages->prev, struct page, lru);
3210
3211                 prefetchw(&page->flags);
3212                 list_del(&page->lru);
3213                 if (!add_to_page_cache_lru(page, mapping,
3214                                         page->index, GFP_NOFS)) {
3215                         __extent_read_full_page(tree, page, get_extent,
3216                                                 &bio, 0, &bio_flags);
3217                 }
3218                 page_cache_release(page);
3219         }
3220         BUG_ON(!list_empty(pages));
3221         if (bio)
3222                 submit_one_bio(READ, bio, 0, bio_flags);
3223         return 0;
3224 }
3225
3226 /*
3227  * basic invalidatepage code, this waits on any locked or writeback
3228  * ranges corresponding to the page, and then deletes any extent state
3229  * records from the tree
3230  */
3231 int extent_invalidatepage(struct extent_io_tree *tree,
3232                           struct page *page, unsigned long offset)
3233 {
3234         struct extent_state *cached_state = NULL;
3235         u64 start = ((u64)page->index << PAGE_CACHE_SHIFT);
3236         u64 end = start + PAGE_CACHE_SIZE - 1;
3237         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
3238
3239         start += (offset + blocksize - 1) & ~(blocksize - 1);
3240         if (start > end)
3241                 return 0;
3242
3243         lock_extent_bits(tree, start, end, 0, &cached_state, GFP_NOFS);
3244         wait_on_page_writeback(page);
3245         clear_extent_bit(tree, start, end,
3246                          EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
3247                          EXTENT_DO_ACCOUNTING,
3248                          1, 1, &cached_state, GFP_NOFS);
3249         return 0;
3250 }
3251
3252 /*
3253  * a helper for releasepage, this tests for areas of the page that
3254  * are locked or under IO and drops the related state bits if it is safe
3255  * to drop the page.
3256  */
3257 int try_release_extent_state(struct extent_map_tree *map,
3258                              struct extent_io_tree *tree, struct page *page,
3259                              gfp_t mask)
3260 {
3261         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
3262         u64 end = start + PAGE_CACHE_SIZE - 1;
3263         int ret = 1;
3264
3265         if (test_range_bit(tree, start, end,
3266                            EXTENT_IOBITS, 0, NULL))
3267                 ret = 0;
3268         else {
3269                 if ((mask & GFP_NOFS) == GFP_NOFS)
3270                         mask = GFP_NOFS;
3271                 /*
3272                  * at this point we can safely clear everything except the
3273                  * locked bit and the nodatasum bit
3274                  */
3275                 ret = clear_extent_bit(tree, start, end,
3276                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
3277                                  0, 0, NULL, mask);
3278
3279                 /* if clear_extent_bit failed for enomem reasons,
3280                  * we can't allow the release to continue.
3281                  */
3282                 if (ret < 0)
3283                         ret = 0;
3284                 else
3285                         ret = 1;
3286         }
3287         return ret;
3288 }
3289
3290 /*
3291  * a helper for releasepage.  As long as there are no locked extents
3292  * in the range corresponding to the page, both state records and extent
3293  * map records are removed
3294  */
3295 int try_release_extent_mapping(struct extent_map_tree *map,
3296                                struct extent_io_tree *tree, struct page *page,
3297                                gfp_t mask)
3298 {
3299         struct extent_map *em;
3300         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
3301         u64 end = start + PAGE_CACHE_SIZE - 1;
3302
3303         if ((mask & __GFP_WAIT) &&
3304             page->mapping->host->i_size > 16 * 1024 * 1024) {
3305                 u64 len;
3306                 while (start <= end) {
3307                         len = end - start + 1;
3308                         write_lock(&map->lock);
3309                         em = lookup_extent_mapping(map, start, len);
3310                         if (!em) {
3311                                 write_unlock(&map->lock);
3312                                 break;
3313                         }
3314                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
3315                             em->start != start) {
3316                                 write_unlock(&map->lock);
3317                                 free_extent_map(em);
3318                                 break;
3319                         }
3320                         if (!test_range_bit(tree, em->start,
3321                                             extent_map_end(em) - 1,
3322                                             EXTENT_LOCKED | EXTENT_WRITEBACK,
3323                                             0, NULL)) {
3324                                 remove_extent_mapping(map, em);
3325                                 /* once for the rb tree */
3326                                 free_extent_map(em);
3327                         }
3328                         start = extent_map_end(em);
3329                         write_unlock(&map->lock);
3330
3331                         /* once for us */
3332                         free_extent_map(em);
3333                 }
3334         }
3335         return try_release_extent_state(map, tree, page, mask);
3336 }
3337
3338 /*
3339  * helper function for fiemap, which doesn't want to see any holes.
3340  * This maps until we find something past 'last'
3341  */
3342 static struct extent_map *get_extent_skip_holes(struct inode *inode,
3343                                                 u64 offset,
3344                                                 u64 last,
3345                                                 get_extent_t *get_extent)
3346 {
3347         u64 sectorsize = BTRFS_I(inode)->root->sectorsize;
3348         struct extent_map *em;
3349         u64 len;
3350
3351         if (offset >= last)
3352                 return NULL;
3353
3354         while(1) {
3355                 len = last - offset;
3356                 if (len == 0)
3357                         break;
3358                 len = (len + sectorsize - 1) & ~(sectorsize - 1);
3359                 em = get_extent(inode, NULL, 0, offset, len, 0);
3360                 if (IS_ERR_OR_NULL(em))
3361                         return em;
3362
3363                 /* if this isn't a hole return it */
3364                 if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) &&
3365                     em->block_start != EXTENT_MAP_HOLE) {
3366                         return em;
3367                 }
3368
3369                 /* this is a hole, advance to the next extent */
3370                 offset = extent_map_end(em);
3371                 free_extent_map(em);
3372                 if (offset >= last)
3373                         break;
3374         }
3375         return NULL;
3376 }
3377
3378 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
3379                 __u64 start, __u64 len, get_extent_t *get_extent)
3380 {
3381         int ret = 0;
3382         u64 off = start;
3383         u64 max = start + len;
3384         u32 flags = 0;
3385         u32 found_type;
3386         u64 last;
3387         u64 last_for_get_extent = 0;
3388         u64 disko = 0;
3389         u64 isize = i_size_read(inode);
3390         struct btrfs_key found_key;
3391         struct extent_map *em = NULL;
3392         struct extent_state *cached_state = NULL;
3393         struct btrfs_path *path;
3394         struct btrfs_file_extent_item *item;
3395         int end = 0;
3396         u64 em_start = 0;
3397         u64 em_len = 0;
3398         u64 em_end = 0;
3399         unsigned long emflags;
3400
3401         if (len == 0)
3402                 return -EINVAL;
3403
3404         path = btrfs_alloc_path();
3405         if (!path)
3406                 return -ENOMEM;
3407         path->leave_spinning = 1;
3408
3409         start = ALIGN(start, BTRFS_I(inode)->root->sectorsize);
3410         len = ALIGN(len, BTRFS_I(inode)->root->sectorsize);
3411
3412         /*
3413          * lookup the last file extent.  We're not using i_size here
3414          * because there might be preallocation past i_size
3415          */
3416         ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root,
3417                                        path, btrfs_ino(inode), -1, 0);
3418         if (ret < 0) {
3419                 btrfs_free_path(path);
3420                 return ret;
3421         }
3422         WARN_ON(!ret);
3423         path->slots[0]--;
3424         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
3425                               struct btrfs_file_extent_item);
3426         btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
3427         found_type = btrfs_key_type(&found_key);
3428
3429         /* No extents, but there might be delalloc bits */
3430         if (found_key.objectid != btrfs_ino(inode) ||
3431             found_type != BTRFS_EXTENT_DATA_KEY) {
3432                 /* have to trust i_size as the end */
3433                 last = (u64)-1;
3434                 last_for_get_extent = isize;
3435         } else {
3436                 /*
3437                  * remember the start of the last extent.  There are a
3438                  * bunch of different factors that go into the length of the
3439                  * extent, so its much less complex to remember where it started
3440                  */
3441                 last = found_key.offset;
3442                 last_for_get_extent = last + 1;
3443         }
3444         btrfs_free_path(path);
3445
3446         /*
3447          * we might have some extents allocated but more delalloc past those
3448          * extents.  so, we trust isize unless the start of the last extent is
3449          * beyond isize
3450          */
3451         if (last < isize) {
3452                 last = (u64)-1;
3453                 last_for_get_extent = isize;
3454         }
3455
3456         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len, 0,
3457                          &cached_state, GFP_NOFS);
3458
3459         em = get_extent_skip_holes(inode, start, last_for_get_extent,
3460                                    get_extent);
3461         if (!em)
3462                 goto out;
3463         if (IS_ERR(em)) {
3464                 ret = PTR_ERR(em);
3465                 goto out;
3466         }
3467
3468         while (!end) {
3469                 u64 offset_in_extent;
3470
3471                 /* break if the extent we found is outside the range */
3472                 if (em->start >= max || extent_map_end(em) < off)
3473                         break;
3474
3475                 /*
3476                  * get_extent may return an extent that starts before our
3477                  * requested range.  We have to make sure the ranges
3478                  * we return to fiemap always move forward and don't
3479                  * overlap, so adjust the offsets here
3480                  */
3481                 em_start = max(em->start, off);
3482
3483                 /*
3484                  * record the offset from the start of the extent
3485                  * for adjusting the disk offset below
3486                  */
3487                 offset_in_extent = em_start - em->start;
3488                 em_end = extent_map_end(em);
3489                 em_len = em_end - em_start;
3490                 emflags = em->flags;
3491                 disko = 0;
3492                 flags = 0;
3493
3494                 /*
3495                  * bump off for our next call to get_extent
3496                  */
3497                 off = extent_map_end(em);
3498                 if (off >= max)
3499                         end = 1;
3500
3501                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
3502                         end = 1;
3503                         flags |= FIEMAP_EXTENT_LAST;
3504                 } else if (em->block_start == EXTENT_MAP_INLINE) {
3505                         flags |= (FIEMAP_EXTENT_DATA_INLINE |
3506                                   FIEMAP_EXTENT_NOT_ALIGNED);
3507                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
3508                         flags |= (FIEMAP_EXTENT_DELALLOC |
3509                                   FIEMAP_EXTENT_UNKNOWN);
3510                 } else {
3511                         disko = em->block_start + offset_in_extent;
3512                 }
3513                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
3514                         flags |= FIEMAP_EXTENT_ENCODED;
3515
3516                 free_extent_map(em);
3517                 em = NULL;
3518                 if ((em_start >= last) || em_len == (u64)-1 ||
3519                    (last == (u64)-1 && isize <= em_end)) {
3520                         flags |= FIEMAP_EXTENT_LAST;
3521                         end = 1;
3522                 }
3523
3524                 /* now scan forward to see if this is really the last extent. */
3525                 em = get_extent_skip_holes(inode, off, last_for_get_extent,
3526                                            get_extent);
3527                 if (IS_ERR(em)) {
3528                         ret = PTR_ERR(em);
3529                         goto out;
3530                 }
3531                 if (!em) {
3532                         flags |= FIEMAP_EXTENT_LAST;
3533                         end = 1;
3534                 }
3535                 ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
3536                                               em_len, flags);
3537                 if (ret)
3538                         goto out_free;
3539         }
3540 out_free:
3541         free_extent_map(em);
3542 out:
3543         unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len,
3544                              &cached_state, GFP_NOFS);
3545         return ret;
3546 }
3547
3548 inline struct page *extent_buffer_page(struct extent_buffer *eb,
3549                                               unsigned long i)
3550 {
3551         struct page *p;
3552         struct address_space *mapping;
3553
3554         if (i == 0)
3555                 return eb->first_page;
3556         i += eb->start >> PAGE_CACHE_SHIFT;
3557         mapping = eb->first_page->mapping;
3558         if (!mapping)
3559                 return NULL;
3560
3561         /*
3562          * extent_buffer_page is only called after pinning the page
3563          * by increasing the reference count.  So we know the page must
3564          * be in the radix tree.
3565          */
3566         rcu_read_lock();
3567         p = radix_tree_lookup(&mapping->page_tree, i);
3568         rcu_read_unlock();
3569
3570         return p;
3571 }
3572
3573 inline unsigned long num_extent_pages(u64 start, u64 len)
3574 {
3575         return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
3576                 (start >> PAGE_CACHE_SHIFT);
3577 }
3578
3579 static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
3580                                                    u64 start,
3581                                                    unsigned long len,
3582                                                    gfp_t mask)
3583 {
3584         struct extent_buffer *eb = NULL;
3585 #if LEAK_DEBUG
3586         unsigned long flags;
3587 #endif
3588
3589         eb = kmem_cache_zalloc(extent_buffer_cache, mask);
3590         if (eb == NULL)
3591                 return NULL;
3592         eb->start = start;
3593         eb->len = len;
3594         rwlock_init(&eb->lock);
3595         atomic_set(&eb->write_locks, 0);
3596         atomic_set(&eb->read_locks, 0);
3597         atomic_set(&eb->blocking_readers, 0);
3598         atomic_set(&eb->blocking_writers, 0);
3599         atomic_set(&eb->spinning_readers, 0);
3600         atomic_set(&eb->spinning_writers, 0);
3601         eb->lock_nested = 0;
3602         init_waitqueue_head(&eb->write_lock_wq);
3603         init_waitqueue_head(&eb->read_lock_wq);
3604
3605 #if LEAK_DEBUG
3606         spin_lock_irqsave(&leak_lock, flags);
3607         list_add(&eb->leak_list, &buffers);
3608         spin_unlock_irqrestore(&leak_lock, flags);
3609 #endif
3610         atomic_set(&eb->refs, 1);
3611
3612         return eb;
3613 }
3614
3615 static void __free_extent_buffer(struct extent_buffer *eb)
3616 {
3617 #if LEAK_DEBUG
3618         unsigned long flags;
3619         spin_lock_irqsave(&leak_lock, flags);
3620         list_del(&eb->leak_list);
3621         spin_unlock_irqrestore(&leak_lock, flags);
3622 #endif
3623         kmem_cache_free(extent_buffer_cache, eb);
3624 }
3625
3626 /*
3627  * Helper for releasing extent buffer page.
3628  */
3629 static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
3630                                                 unsigned long start_idx)
3631 {
3632         unsigned long index;
3633         struct page *page;
3634
3635         if (!eb->first_page)
3636                 return;
3637
3638         index = num_extent_pages(eb->start, eb->len);
3639         if (start_idx >= index)
3640                 return;
3641
3642         do {
3643                 index--;
3644                 page = extent_buffer_page(eb, index);
3645                 if (page)
3646                         page_cache_release(page);
3647         } while (index != start_idx);
3648 }
3649
3650 /*
3651  * Helper for releasing the extent buffer.
3652  */
3653 static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
3654 {
3655         btrfs_release_extent_buffer_page(eb, 0);
3656         __free_extent_buffer(eb);
3657 }
3658
3659 struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
3660                                           u64 start, unsigned long len,
3661                                           struct page *page0)
3662 {
3663         unsigned long num_pages = num_extent_pages(start, len);
3664         unsigned long i;
3665         unsigned long index = start >> PAGE_CACHE_SHIFT;
3666         struct extent_buffer *eb;
3667         struct extent_buffer *exists = NULL;
3668         struct page *p;
3669         struct address_space *mapping = tree->mapping;
3670         int uptodate = 1;
3671         int ret;
3672
3673         rcu_read_lock();
3674         eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
3675         if (eb && atomic_inc_not_zero(&eb->refs)) {
3676                 rcu_read_unlock();
3677                 mark_page_accessed(eb->first_page);
3678                 return eb;
3679         }
3680         rcu_read_unlock();
3681
3682         eb = __alloc_extent_buffer(tree, start, len, GFP_NOFS);
3683         if (!eb)
3684                 return NULL;
3685
3686         if (page0) {
3687                 eb->first_page = page0;
3688                 i = 1;
3689                 index++;
3690                 page_cache_get(page0);
3691                 mark_page_accessed(page0);
3692                 set_page_extent_mapped(page0);
3693                 set_page_extent_head(page0, len);
3694                 uptodate = PageUptodate(page0);
3695         } else {
3696                 i = 0;
3697         }
3698         for (; i < num_pages; i++, index++) {
3699                 p = find_or_create_page(mapping, index, GFP_NOFS);
3700                 if (!p) {
3701                         WARN_ON(1);
3702                         goto free_eb;
3703                 }
3704                 set_page_extent_mapped(p);
3705                 mark_page_accessed(p);
3706                 if (i == 0) {
3707                         eb->first_page = p;
3708                         set_page_extent_head(p, len);
3709                 } else {
3710                         set_page_private(p, EXTENT_PAGE_PRIVATE);
3711                 }
3712                 if (!PageUptodate(p))
3713                         uptodate = 0;
3714
3715                 /*
3716                  * see below about how we avoid a nasty race with release page
3717                  * and why we unlock later
3718                  */
3719                 if (i != 0)
3720                         unlock_page(p);
3721         }
3722         if (uptodate)
3723                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3724
3725         ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
3726         if (ret)
3727                 goto free_eb;
3728
3729         spin_lock(&tree->buffer_lock);
3730         ret = radix_tree_insert(&tree->buffer, start >> PAGE_CACHE_SHIFT, eb);
3731         if (ret == -EEXIST) {
3732                 exists = radix_tree_lookup(&tree->buffer,
3733                                                 start >> PAGE_CACHE_SHIFT);
3734                 /* add one reference for the caller */
3735                 atomic_inc(&exists->refs);
3736                 spin_unlock(&tree->buffer_lock);
3737                 radix_tree_preload_end();
3738                 goto free_eb;
3739         }
3740         /* add one reference for the tree */
3741         atomic_inc(&eb->refs);
3742         spin_unlock(&tree->buffer_lock);
3743         radix_tree_preload_end();
3744
3745         /*
3746          * there is a race where release page may have
3747          * tried to find this extent buffer in the radix
3748          * but failed.  It will tell the VM it is safe to
3749          * reclaim the, and it will clear the page private bit.
3750          * We must make sure to set the page private bit properly
3751          * after the extent buffer is in the radix tree so
3752          * it doesn't get lost
3753          */
3754         set_page_extent_mapped(eb->first_page);
3755         set_page_extent_head(eb->first_page, eb->len);
3756         if (!page0)
3757                 unlock_page(eb->first_page);
3758         return eb;
3759
3760 free_eb:
3761         if (eb->first_page && !page0)
3762                 unlock_page(eb->first_page);
3763
3764         if (!atomic_dec_and_test(&eb->refs))
3765                 return exists;
3766         btrfs_release_extent_buffer(eb);
3767         return exists;
3768 }
3769
3770 struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
3771                                          u64 start, unsigned long len)
3772 {
3773         struct extent_buffer *eb;
3774
3775         rcu_read_lock();
3776         eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
3777         if (eb && atomic_inc_not_zero(&eb->refs)) {
3778                 rcu_read_unlock();
3779                 mark_page_accessed(eb->first_page);
3780                 return eb;
3781         }
3782         rcu_read_unlock();
3783
3784         return NULL;
3785 }
3786
3787 void free_extent_buffer(struct extent_buffer *eb)
3788 {
3789         if (!eb)
3790                 return;
3791
3792         if (!atomic_dec_and_test(&eb->refs))
3793                 return;
3794
3795         WARN_ON(1);
3796 }
3797
3798 int clear_extent_buffer_dirty(struct extent_io_tree *tree,
3799                               struct extent_buffer *eb)
3800 {
3801         unsigned long i;
3802         unsigned long num_pages;
3803         struct page *page;
3804
3805         num_pages = num_extent_pages(eb->start, eb->len);
3806
3807         for (i = 0; i < num_pages; i++) {
3808                 page = extent_buffer_page(eb, i);
3809                 if (!PageDirty(page))
3810                         continue;
3811
3812                 lock_page(page);
3813                 WARN_ON(!PagePrivate(page));
3814
3815                 set_page_extent_mapped(page);
3816                 if (i == 0)
3817                         set_page_extent_head(page, eb->len);
3818
3819                 clear_page_dirty_for_io(page);
3820                 spin_lock_irq(&page->mapping->tree_lock);
3821                 if (!PageDirty(page)) {
3822                         radix_tree_tag_clear(&page->mapping->page_tree,
3823                                                 page_index(page),
3824                                                 PAGECACHE_TAG_DIRTY);
3825                 }
3826                 spin_unlock_irq(&page->mapping->tree_lock);
3827                 ClearPageError(page);
3828                 unlock_page(page);
3829         }
3830         return 0;
3831 }
3832
3833 int set_extent_buffer_dirty(struct extent_io_tree *tree,
3834                              struct extent_buffer *eb)
3835 {
3836         unsigned long i;
3837         unsigned long num_pages;
3838         int was_dirty = 0;
3839
3840         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
3841         num_pages = num_extent_pages(eb->start, eb->len);
3842         for (i = 0; i < num_pages; i++)
3843                 __set_page_dirty_nobuffers(extent_buffer_page(eb, i));
3844         return was_dirty;
3845 }
3846
3847 static int __eb_straddles_pages(u64 start, u64 len)
3848 {
3849         if (len < PAGE_CACHE_SIZE)
3850                 return 1;
3851         if (start & (PAGE_CACHE_SIZE - 1))
3852                 return 1;
3853         if ((start + len) & (PAGE_CACHE_SIZE - 1))
3854                 return 1;
3855         return 0;
3856 }
3857
3858 static int eb_straddles_pages(struct extent_buffer *eb)
3859 {
3860         return __eb_straddles_pages(eb->start, eb->len);
3861 }
3862
3863 int clear_extent_buffer_uptodate(struct extent_io_tree *tree,
3864                                 struct extent_buffer *eb,
3865                                 struct extent_state **cached_state)
3866 {
3867         unsigned long i;
3868         struct page *page;
3869         unsigned long num_pages;
3870
3871         num_pages = num_extent_pages(eb->start, eb->len);
3872         clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3873
3874         clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
3875                               cached_state, GFP_NOFS);
3876
3877         for (i = 0; i < num_pages; i++) {
3878                 page = extent_buffer_page(eb, i);
3879                 if (page)
3880                         ClearPageUptodate(page);
3881         }
3882         return 0;
3883 }
3884
3885 int set_extent_buffer_uptodate(struct extent_io_tree *tree,
3886                                 struct extent_buffer *eb)
3887 {
3888         unsigned long i;
3889         struct page *page;
3890         unsigned long num_pages;
3891
3892         num_pages = num_extent_pages(eb->start, eb->len);
3893
3894         if (eb_straddles_pages(eb)) {
3895                 set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
3896                                     NULL, GFP_NOFS);
3897         }
3898         for (i = 0; i < num_pages; i++) {
3899                 page = extent_buffer_page(eb, i);
3900                 if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
3901                     ((i == num_pages - 1) &&
3902                      ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
3903                         check_page_uptodate(tree, page);
3904                         continue;
3905                 }
3906                 SetPageUptodate(page);
3907         }
3908         return 0;
3909 }
3910
3911 int extent_range_uptodate(struct extent_io_tree *tree,
3912                           u64 start, u64 end)
3913 {
3914         struct page *page;
3915         int ret;
3916         int pg_uptodate = 1;
3917         int uptodate;
3918         unsigned long index;
3919
3920         if (__eb_straddles_pages(start, end - start + 1)) {
3921                 ret = test_range_bit(tree, start, end,
3922                                      EXTENT_UPTODATE, 1, NULL);
3923                 if (ret)
3924                         return 1;
3925         }
3926         while (start <= end) {
3927                 index = start >> PAGE_CACHE_SHIFT;
3928                 page = find_get_page(tree->mapping, index);
3929                 if (!page)
3930                         return 1;
3931                 uptodate = PageUptodate(page);
3932                 page_cache_release(page);
3933                 if (!uptodate) {
3934                         pg_uptodate = 0;
3935                         break;
3936                 }
3937                 start += PAGE_CACHE_SIZE;
3938         }
3939         return pg_uptodate;
3940 }
3941
3942 int extent_buffer_uptodate(struct extent_io_tree *tree,
3943                            struct extent_buffer *eb,
3944                            struct extent_state *cached_state)
3945 {
3946         int ret = 0;
3947         unsigned long num_pages;
3948         unsigned long i;
3949         struct page *page;
3950         int pg_uptodate = 1;
3951
3952         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
3953                 return 1;
3954
3955         if (eb_straddles_pages(eb)) {
3956                 ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1,
3957                                    EXTENT_UPTODATE, 1, cached_state);
3958                 if (ret)
3959                         return ret;
3960         }
3961
3962         num_pages = num_extent_pages(eb->start, eb->len);
3963         for (i = 0; i < num_pages; i++) {
3964                 page = extent_buffer_page(eb, i);
3965                 if (!PageUptodate(page)) {
3966                         pg_uptodate = 0;
3967                         break;
3968                 }
3969         }
3970         return pg_uptodate;
3971 }
3972
3973 int read_extent_buffer_pages(struct extent_io_tree *tree,
3974                              struct extent_buffer *eb, u64 start, int wait,
3975                              get_extent_t *get_extent, int mirror_num)
3976 {
3977         unsigned long i;
3978         unsigned long start_i;
3979         struct page *page;
3980         int err;
3981         int ret = 0;
3982         int locked_pages = 0;
3983         int all_uptodate = 1;
3984         int inc_all_pages = 0;
3985         unsigned long num_pages;
3986         struct bio *bio = NULL;
3987         unsigned long bio_flags = 0;
3988
3989         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
3990                 return 0;
3991
3992         if (eb_straddles_pages(eb)) {
3993                 if (test_range_bit(tree, eb->start, eb->start + eb->len - 1,
3994                                    EXTENT_UPTODATE, 1, NULL)) {
3995                         return 0;
3996                 }
3997         }
3998
3999         if (start) {
4000                 WARN_ON(start < eb->start);
4001                 start_i = (start >> PAGE_CACHE_SHIFT) -
4002                         (eb->start >> PAGE_CACHE_SHIFT);
4003         } else {
4004                 start_i = 0;
4005         }
4006
4007         num_pages = num_extent_pages(eb->start, eb->len);
4008         for (i = start_i; i < num_pages; i++) {
4009                 page = extent_buffer_page(eb, i);
4010                 if (wait == WAIT_NONE) {
4011                         if (!trylock_page(page))
4012                                 goto unlock_exit;
4013                 } else {
4014                         lock_page(page);
4015                 }
4016                 locked_pages++;
4017                 if (!PageUptodate(page))
4018                         all_uptodate = 0;
4019         }
4020         if (all_uptodate) {
4021                 if (start_i == 0)
4022                         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
4023                 goto unlock_exit;
4024         }
4025
4026         for (i = start_i; i < num_pages; i++) {
4027                 page = extent_buffer_page(eb, i);
4028
4029                 WARN_ON(!PagePrivate(page));
4030
4031                 set_page_extent_mapped(page);
4032                 if (i == 0)
4033                         set_page_extent_head(page, eb->len);
4034
4035                 if (inc_all_pages)
4036                         page_cache_get(page);
4037                 if (!PageUptodate(page)) {
4038                         if (start_i == 0)
4039                                 inc_all_pages = 1;
4040                         ClearPageError(page);
4041                         err = __extent_read_full_page(tree, page,
4042                                                       get_extent, &bio,
4043                                                       mirror_num, &bio_flags);
4044                         if (err)
4045                                 ret = err;
4046                 } else {
4047                         unlock_page(page);
4048                 }
4049         }
4050
4051         if (bio)
4052                 submit_one_bio(READ, bio, mirror_num, bio_flags);
4053
4054         if (ret || wait != WAIT_COMPLETE)
4055                 return ret;
4056
4057         for (i = start_i; i < num_pages; i++) {
4058                 page = extent_buffer_page(eb, i);
4059                 wait_on_page_locked(page);
4060                 if (!PageUptodate(page))
4061                         ret = -EIO;
4062         }
4063
4064         if (!ret)
4065                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
4066         return ret;
4067
4068 unlock_exit:
4069         i = start_i;
4070         while (locked_pages > 0) {
4071                 page = extent_buffer_page(eb, i);
4072                 i++;
4073                 unlock_page(page);
4074                 locked_pages--;
4075         }
4076         return ret;
4077 }
4078
4079 void read_extent_buffer(struct extent_buffer *eb, void *dstv,
4080                         unsigned long start,
4081                         unsigned long len)
4082 {
4083         size_t cur;
4084         size_t offset;
4085         struct page *page;
4086         char *kaddr;
4087         char *dst = (char *)dstv;
4088         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
4089         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
4090
4091         WARN_ON(start > eb->len);
4092         WARN_ON(start + len > eb->start + eb->len);
4093
4094         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
4095
4096         while (len > 0) {
4097                 page = extent_buffer_page(eb, i);
4098
4099                 cur = min(len, (PAGE_CACHE_SIZE - offset));
4100                 kaddr = page_address(page);
4101                 memcpy(dst, kaddr + offset, cur);
4102
4103                 dst += cur;
4104                 len -= cur;
4105                 offset = 0;
4106                 i++;
4107         }
4108 }
4109
4110 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
4111                                unsigned long min_len, char **map,
4112                                unsigned long *map_start,
4113                                unsigned long *map_len)
4114 {
4115         size_t offset = start & (PAGE_CACHE_SIZE - 1);
4116         char *kaddr;
4117         struct page *p;
4118         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
4119         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
4120         unsigned long end_i = (start_offset + start + min_len - 1) >>
4121                 PAGE_CACHE_SHIFT;
4122
4123         if (i != end_i)
4124                 return -EINVAL;
4125
4126         if (i == 0) {
4127                 offset = start_offset;
4128                 *map_start = 0;
4129         } else {
4130                 offset = 0;
4131                 *map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset;
4132         }
4133
4134         if (start + min_len > eb->len) {
4135                 printk(KERN_ERR "btrfs bad mapping eb start %llu len %lu, "
4136                        "wanted %lu %lu\n", (unsigned long long)eb->start,
4137                        eb->len, start, min_len);
4138                 WARN_ON(1);
4139                 return -EINVAL;
4140         }
4141
4142         p = extent_buffer_page(eb, i);
4143         kaddr = page_address(p);
4144         *map = kaddr + offset;
4145         *map_len = PAGE_CACHE_SIZE - offset;
4146         return 0;
4147 }
4148
4149 int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
4150                           unsigned long start,
4151                           unsigned long len)
4152 {
4153         size_t cur;
4154         size_t offset;
4155         struct page *page;
4156         char *kaddr;
4157         char *ptr = (char *)ptrv;
4158         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
4159         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
4160         int ret = 0;
4161
4162         WARN_ON(start > eb->len);
4163         WARN_ON(start + len > eb->start + eb->len);
4164
4165         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
4166
4167         while (len > 0) {
4168                 page = extent_buffer_page(eb, i);
4169
4170                 cur = min(len, (PAGE_CACHE_SIZE - offset));
4171
4172                 kaddr = page_address(page);
4173                 ret = memcmp(ptr, kaddr + offset, cur);
4174                 if (ret)
4175                         break;
4176
4177                 ptr += cur;
4178                 len -= cur;
4179                 offset = 0;
4180                 i++;
4181         }
4182         return ret;
4183 }
4184
4185 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
4186                          unsigned long start, unsigned long len)
4187 {
4188         size_t cur;
4189         size_t offset;
4190         struct page *page;
4191         char *kaddr;
4192         char *src = (char *)srcv;
4193         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
4194         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
4195
4196         WARN_ON(start > eb->len);
4197         WARN_ON(start + len > eb->start + eb->len);
4198
4199         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
4200
4201         while (len > 0) {
4202                 page = extent_buffer_page(eb, i);
4203                 WARN_ON(!PageUptodate(page));
4204
4205                 cur = min(len, PAGE_CACHE_SIZE - offset);
4206                 kaddr = page_address(page);
4207                 memcpy(kaddr + offset, src, cur);
4208
4209                 src += cur;
4210                 len -= cur;
4211                 offset = 0;
4212                 i++;
4213         }
4214 }
4215
4216 void memset_extent_buffer(struct extent_buffer *eb, char c,
4217                           unsigned long start, unsigned long len)
4218 {
4219         size_t cur;
4220         size_t offset;
4221         struct page *page;
4222         char *kaddr;
4223         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
4224         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
4225
4226         WARN_ON(start > eb->len);
4227         WARN_ON(start + len > eb->start + eb->len);
4228
4229         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
4230
4231         while (len > 0) {
4232                 page = extent_buffer_page(eb, i);
4233                 WARN_ON(!PageUptodate(page));
4234
4235                 cur = min(len, PAGE_CACHE_SIZE - offset);
4236                 kaddr = page_address(page);
4237                 memset(kaddr + offset, c, cur);
4238
4239                 len -= cur;
4240                 offset = 0;
4241                 i++;
4242         }
4243 }
4244
4245 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
4246                         unsigned long dst_offset, unsigned long src_offset,
4247                         unsigned long len)
4248 {
4249         u64 dst_len = dst->len;
4250         size_t cur;
4251         size_t offset;
4252         struct page *page;
4253         char *kaddr;
4254         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
4255         unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
4256
4257         WARN_ON(src->len != dst_len);
4258
4259         offset = (start_offset + dst_offset) &
4260                 ((unsigned long)PAGE_CACHE_SIZE - 1);
4261
4262         while (len > 0) {
4263                 page = extent_buffer_page(dst, i);
4264                 WARN_ON(!PageUptodate(page));
4265
4266                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
4267
4268                 kaddr = page_address(page);
4269                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
4270
4271                 src_offset += cur;
4272                 len -= cur;
4273                 offset = 0;
4274                 i++;
4275         }
4276 }
4277
4278 static void move_pages(struct page *dst_page, struct page *src_page,
4279                        unsigned long dst_off, unsigned long src_off,
4280                        unsigned long len)
4281 {
4282         char *dst_kaddr = page_address(dst_page);
4283         if (dst_page == src_page) {
4284                 memmove(dst_kaddr + dst_off, dst_kaddr + src_off, len);
4285         } else {
4286                 char *src_kaddr = page_address(src_page);
4287                 char *p = dst_kaddr + dst_off + len;
4288                 char *s = src_kaddr + src_off + len;
4289
4290                 while (len--)
4291                         *--p = *--s;
4292         }
4293 }
4294
4295 static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
4296 {
4297         unsigned long distance = (src > dst) ? src - dst : dst - src;
4298         return distance < len;
4299 }
4300
4301 static void copy_pages(struct page *dst_page, struct page *src_page,
4302                        unsigned long dst_off, unsigned long src_off,
4303                        unsigned long len)
4304 {
4305         char *dst_kaddr = page_address(dst_page);
4306         char *src_kaddr;
4307
4308         if (dst_page != src_page) {
4309                 src_kaddr = page_address(src_page);
4310         } else {
4311                 src_kaddr = dst_kaddr;
4312                 BUG_ON(areas_overlap(src_off, dst_off, len));
4313         }
4314
4315         memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
4316 }
4317
4318 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
4319                            unsigned long src_offset, unsigned long len)
4320 {
4321         size_t cur;
4322         size_t dst_off_in_page;
4323         size_t src_off_in_page;
4324         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
4325         unsigned long dst_i;
4326         unsigned long src_i;
4327
4328         if (src_offset + len > dst->len) {
4329                 printk(KERN_ERR "btrfs memmove bogus src_offset %lu move "
4330                        "len %lu dst len %lu\n", src_offset, len, dst->len);
4331                 BUG_ON(1);
4332         }
4333         if (dst_offset + len > dst->len) {
4334                 printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move "
4335                        "len %lu dst len %lu\n", dst_offset, len, dst->len);
4336                 BUG_ON(1);
4337         }
4338
4339         while (len > 0) {
4340                 dst_off_in_page = (start_offset + dst_offset) &
4341                         ((unsigned long)PAGE_CACHE_SIZE - 1);
4342                 src_off_in_page = (start_offset + src_offset) &
4343                         ((unsigned long)PAGE_CACHE_SIZE - 1);
4344
4345                 dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
4346                 src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT;
4347
4348                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE -
4349                                                src_off_in_page));
4350                 cur = min_t(unsigned long, cur,
4351                         (unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page));
4352
4353                 copy_pages(extent_buffer_page(dst, dst_i),
4354                            extent_buffer_page(dst, src_i),
4355                            dst_off_in_page, src_off_in_page, cur);
4356
4357                 src_offset += cur;
4358                 dst_offset += cur;
4359                 len -= cur;
4360         }
4361 }
4362
4363 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
4364                            unsigned long src_offset, unsigned long len)
4365 {
4366         size_t cur;
4367         size_t dst_off_in_page;
4368         size_t src_off_in_page;
4369         unsigned long dst_end = dst_offset + len - 1;
4370         unsigned long src_end = src_offset + len - 1;
4371         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
4372         unsigned long dst_i;
4373         unsigned long src_i;
4374
4375         if (src_offset + len > dst->len) {
4376                 printk(KERN_ERR "btrfs memmove bogus src_offset %lu move "
4377                        "len %lu len %lu\n", src_offset, len, dst->len);
4378                 BUG_ON(1);
4379         }
4380         if (dst_offset + len > dst->len) {
4381                 printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move "
4382                        "len %lu len %lu\n", dst_offset, len, dst->len);
4383                 BUG_ON(1);
4384         }
4385         if (!areas_overlap(src_offset, dst_offset, len)) {
4386                 memcpy_extent_buffer(dst, dst_offset, src_offset, len);
4387                 return;
4388         }
4389         while (len > 0) {
4390                 dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT;
4391                 src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT;
4392
4393                 dst_off_in_page = (start_offset + dst_end) &
4394                         ((unsigned long)PAGE_CACHE_SIZE - 1);
4395                 src_off_in_page = (start_offset + src_end) &
4396                         ((unsigned long)PAGE_CACHE_SIZE - 1);
4397
4398                 cur = min_t(unsigned long, len, src_off_in_page + 1);
4399                 cur = min(cur, dst_off_in_page + 1);
4400                 move_pages(extent_buffer_page(dst, dst_i),
4401                            extent_buffer_page(dst, src_i),
4402                            dst_off_in_page - cur + 1,
4403                            src_off_in_page - cur + 1, cur);
4404
4405                 dst_end -= cur;
4406                 src_end -= cur;
4407                 len -= cur;
4408         }
4409 }
4410
4411 static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
4412 {
4413         struct extent_buffer *eb =
4414                         container_of(head, struct extent_buffer, rcu_head);
4415
4416         btrfs_release_extent_buffer(eb);
4417 }
4418
4419 int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
4420 {
4421         u64 start = page_offset(page);
4422         struct extent_buffer *eb;
4423         int ret = 1;
4424
4425         spin_lock(&tree->buffer_lock);
4426         eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
4427         if (!eb) {
4428                 spin_unlock(&tree->buffer_lock);
4429                 return ret;
4430         }
4431
4432         if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
4433                 ret = 0;
4434                 goto out;
4435         }
4436
4437         /*
4438          * set @eb->refs to 0 if it is already 1, and then release the @eb.
4439          * Or go back.
4440          */
4441         if (atomic_cmpxchg(&eb->refs, 1, 0) != 1) {
4442                 ret = 0;
4443                 goto out;
4444         }
4445
4446         radix_tree_delete(&tree->buffer, start >> PAGE_CACHE_SHIFT);
4447 out:
4448         spin_unlock(&tree->buffer_lock);
4449
4450         /* at this point we can safely release the extent buffer */
4451         if (atomic_read(&eb->refs) == 0)
4452                 call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
4453         return ret;
4454 }