SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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/gfp.h>
   6 #include <linux/pagemap.h>
   7 #include <linux/page-flags.h>
   8 #include <linux/module.h>
   9 #include <linux/spinlock.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/swap.h>
  12 #include <linux/version.h>
  13 #include <linux/writeback.h>
  14 #include <linux/pagevec.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
  21 /* temporary define until extent_map moves out of btrfs */
  22 struct kmem_cache *btrfs_cache_create(const char *name, size_t size,
  23                                        unsigned long extra_flags,
  24                                        void (*ctor)(void *, struct kmem_cache *,
  25                                                     unsigned long));
  26
  27 static struct kmem_cache *extent_state_cache;
  28 static struct kmem_cache *extent_buffer_cache;
  29
  30 static LIST_HEAD(buffers);
  31 static LIST_HEAD(states);
  32 static spinlock_t leak_lock = SPIN_LOCK_UNLOCKED;
  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
  48 int __init extent_io_init(void)
  49 {
  50         extent_state_cache = btrfs_cache_create("extent_state",
  51                                             sizeof(struct extent_state), 0,
  52                                             NULL);
  53         if (!extent_state_cache)
  54                 return -ENOMEM;
  55
  56         extent_buffer_cache = btrfs_cache_create("extent_buffers",
  57                                             sizeof(struct extent_buffer), 0,
  58                                             NULL);
  59         if (!extent_buffer_cache)
  60                 goto free_state_cache;
  61         return 0;
  62
  63 free_state_cache:
  64         kmem_cache_destroy(extent_state_cache);
  65         return -ENOMEM;
  66 }
  67
  68 void extent_io_exit(void)
  69 {
  70         struct extent_state *state;
  71         struct extent_buffer *eb;
  72
  73         while (!list_empty(&states)) {
  74                 state = list_entry(states.next, struct extent_state, leak_list);
  75                 printk("state leak: start %Lu end %Lu state %lu in tree %p refs %d\n", state->start, state->end, state->state, state->tree, atomic_read(&state->refs));
  76                 list_del(&state->leak_list);
  77                 kmem_cache_free(extent_state_cache, state);
  78
  79         }
  80
  81         while (!list_empty(&buffers)) {
  82                 eb = list_entry(buffers.next, struct extent_buffer, leak_list);
  83                 printk("buffer leak start %Lu len %lu refs %d\n", eb->start, eb->len, atomic_read(&eb->refs));
  84                 list_del(&eb->leak_list);
  85                 kmem_cache_free(extent_buffer_cache, eb);
  86         }
  87         if (extent_state_cache)
  88                 kmem_cache_destroy(extent_state_cache);
  89         if (extent_buffer_cache)
  90                 kmem_cache_destroy(extent_buffer_cache);
  91 }
  92
  93 void extent_io_tree_init(struct extent_io_tree *tree,
  94                           struct address_space *mapping, gfp_t mask)
  95 {
  96         tree->state.rb_node = NULL;
  97         tree->buffer.rb_node = NULL;
  98         tree->ops = NULL;
  99         tree->dirty_bytes = 0;
 100         spin_lock_init(&tree->lock);
 101         spin_lock_init(&tree->buffer_lock);
 102         tree->mapping = mapping;
 103 }
 104 EXPORT_SYMBOL(extent_io_tree_init);
 105
 106 struct extent_state *alloc_extent_state(gfp_t mask)
 107 {
 108         struct extent_state *state;
 109         unsigned long flags;
 110
 111         state = kmem_cache_alloc(extent_state_cache, mask);
 112         if (!state)
 113                 return state;
 114         state->state = 0;
 115         state->private = 0;
 116         state->tree = NULL;
 117         spin_lock_irqsave(&leak_lock, flags);
 118         list_add(&state->leak_list, &states);
 119         spin_unlock_irqrestore(&leak_lock, flags);
 120
 121         atomic_set(&state->refs, 1);
 122         init_waitqueue_head(&state->wq);
 123         return state;
 124 }
 125 EXPORT_SYMBOL(alloc_extent_state);
 126
 127 void free_extent_state(struct extent_state *state)
 128 {
 129         if (!state)
 130                 return;
 131         if (atomic_dec_and_test(&state->refs)) {
 132                 unsigned long flags;
 133                 WARN_ON(state->tree);
 134                 spin_lock_irqsave(&leak_lock, flags);
 135                 list_del(&state->leak_list);
 136                 spin_unlock_irqrestore(&leak_lock, flags);
 137                 kmem_cache_free(extent_state_cache, state);
 138         }
 139 }
 140 EXPORT_SYMBOL(free_extent_state);
 141
 142 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
 143                                    struct rb_node *node)
 144 {
 145         struct rb_node ** p = &root->rb_node;
 146         struct rb_node * parent = NULL;
 147         struct tree_entry *entry;
 148
 149         while(*p) {
 150                 parent = *p;
 151                 entry = rb_entry(parent, struct tree_entry, rb_node);
 152
 153                 if (offset < entry->start)
 154                         p = &(*p)->rb_left;
 155                 else if (offset > entry->end)
 156                         p = &(*p)->rb_right;
 157                 else
 158                         return parent;
 159         }
 160
 161         entry = rb_entry(node, struct tree_entry, rb_node);
 162         rb_link_node(node, parent, p);
 163         rb_insert_color(node, root);
 164         return NULL;
 165 }
 166
 167 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 168                                      struct rb_node **prev_ret,
 169                                      struct rb_node **next_ret)
 170 {
 171         struct rb_root *root = &tree->state;
 172         struct rb_node * n = root->rb_node;
 173         struct rb_node *prev = NULL;
 174         struct rb_node *orig_prev = NULL;
 175         struct tree_entry *entry;
 176         struct tree_entry *prev_entry = NULL;
 177
 178         while(n) {
 179                 entry = rb_entry(n, struct tree_entry, rb_node);
 180                 prev = n;
 181                 prev_entry = entry;
 182
 183                 if (offset < entry->start)
 184                         n = n->rb_left;
 185                 else if (offset > entry->end)
 186                         n = n->rb_right;
 187                 else {
 188                         return n;
 189                 }
 190         }
 191
 192         if (prev_ret) {
 193                 orig_prev = prev;
 194                 while(prev && offset > prev_entry->end) {
 195                         prev = rb_next(prev);
 196                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 197                 }
 198                 *prev_ret = prev;
 199                 prev = orig_prev;
 200         }
 201
 202         if (next_ret) {
 203                 prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 204                 while(prev && offset < prev_entry->start) {
 205                         prev = rb_prev(prev);
 206                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 207                 }
 208                 *next_ret = prev;
 209         }
 210         return NULL;
 211 }
 212
 213 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
 214                                           u64 offset)
 215 {
 216         struct rb_node *prev = NULL;
 217         struct rb_node *ret;
 218
 219         ret = __etree_search(tree, offset, &prev, NULL);
 220         if (!ret) {
 221                 return prev;
 222         }
 223         return ret;
 224 }
 225
 226 static struct extent_buffer *buffer_tree_insert(struct extent_io_tree *tree,
 227                                           u64 offset, struct rb_node *node)
 228 {
 229         struct rb_root *root = &tree->buffer;
 230         struct rb_node ** p = &root->rb_node;
 231         struct rb_node * parent = NULL;
 232         struct extent_buffer *eb;
 233
 234         while(*p) {
 235                 parent = *p;
 236                 eb = rb_entry(parent, struct extent_buffer, rb_node);
 237
 238                 if (offset < eb->start)
 239                         p = &(*p)->rb_left;
 240                 else if (offset > eb->start)
 241                         p = &(*p)->rb_right;
 242                 else
 243                         return eb;
 244         }
 245
 246         rb_link_node(node, parent, p);
 247         rb_insert_color(node, root);
 248         return NULL;
 249 }
 250
 251 static struct extent_buffer *buffer_search(struct extent_io_tree *tree,
 252                                            u64 offset)
 253 {
 254         struct rb_root *root = &tree->buffer;
 255         struct rb_node * n = root->rb_node;
 256         struct extent_buffer *eb;
 257
 258         while(n) {
 259                 eb = rb_entry(n, struct extent_buffer, rb_node);
 260                 if (offset < eb->start)
 261                         n = n->rb_left;
 262                 else if (offset > eb->start)
 263                         n = n->rb_right;
 264                 else
 265                         return eb;
 266         }
 267         return NULL;
 268 }
 269
 270 /*
 271  * utility function to look for merge candidates inside a given range.
 272  * Any extents with matching state are merged together into a single
 273  * extent in the tree.  Extents with EXTENT_IO in their state field
 274  * are not merged because the end_io handlers need to be able to do
 275  * operations on them without sleeping (or doing allocations/splits).
 276  *
 277  * This should be called with the tree lock held.
 278  */
 279 static int merge_state(struct extent_io_tree *tree,
 280                        struct extent_state *state)
 281 {
 282         struct extent_state *other;
 283         struct rb_node *other_node;
 284
 285         if (state->state & EXTENT_IOBITS)
 286                 return 0;
 287
 288         other_node = rb_prev(&state->rb_node);
 289         if (other_node) {
 290                 other = rb_entry(other_node, struct extent_state, rb_node);
 291                 if (other->end == state->start - 1 &&
 292                     other->state == state->state) {
 293                         state->start = other->start;
 294                         other->tree = NULL;
 295                         rb_erase(&other->rb_node, &tree->state);
 296                         free_extent_state(other);
 297                 }
 298         }
 299         other_node = rb_next(&state->rb_node);
 300         if (other_node) {
 301                 other = rb_entry(other_node, struct extent_state, rb_node);
 302                 if (other->start == state->end + 1 &&
 303                     other->state == state->state) {
 304                         other->start = state->start;
 305                         state->tree = NULL;
 306                         rb_erase(&state->rb_node, &tree->state);
 307                         free_extent_state(state);
 308                 }
 309         }
 310         return 0;
 311 }
 312
 313 static void set_state_cb(struct extent_io_tree *tree,
 314                          struct extent_state *state,
 315                          unsigned long bits)
 316 {
 317         if (tree->ops && tree->ops->set_bit_hook) {
 318                 tree->ops->set_bit_hook(tree->mapping->host, state->start,
 319                                         state->end, state->state, bits);
 320         }
 321 }
 322
 323 static void clear_state_cb(struct extent_io_tree *tree,
 324                            struct extent_state *state,
 325                            unsigned long bits)
 326 {
 327         if (tree->ops && tree->ops->set_bit_hook) {
 328                 tree->ops->clear_bit_hook(tree->mapping->host, state->start,
 329                                           state->end, state->state, bits);
 330         }
 331 }
 332
 333 /*
 334  * insert an extent_state struct into the tree.  'bits' are set on the
 335  * struct before it is inserted.
 336  *
 337  * This may return -EEXIST if the extent is already there, in which case the
 338  * state struct is freed.
 339  *
 340  * The tree lock is not taken internally.  This is a utility function and
 341  * probably isn't what you want to call (see set/clear_extent_bit).
 342  */
 343 static int insert_state(struct extent_io_tree *tree,
 344                         struct extent_state *state, u64 start, u64 end,
 345                         int bits)
 346 {
 347         struct rb_node *node;
 348
 349         if (end < start) {
 350                 printk("end < start %Lu %Lu\n", end, start);
 351                 WARN_ON(1);
 352         }
 353         if (bits & EXTENT_DIRTY)
 354                 tree->dirty_bytes += end - start + 1;
 355         set_state_cb(tree, state, bits);
 356         state->state |= bits;
 357         state->start = start;
 358         state->end = end;
 359         node = tree_insert(&tree->state, end, &state->rb_node);
 360         if (node) {
 361                 struct extent_state *found;
 362                 found = rb_entry(node, struct extent_state, rb_node);
 363                 printk("found node %Lu %Lu on insert of %Lu %Lu\n", found->start, found->end, start, end);
 364                 free_extent_state(state);
 365                 return -EEXIST;
 366         }
 367         state->tree = tree;
 368         merge_state(tree, state);
 369         return 0;
 370 }
 371
 372 /*
 373  * split a given extent state struct in two, inserting the preallocated
 374  * struct 'prealloc' as the newly created second half.  'split' indicates an
 375  * offset inside 'orig' where it should be split.
 376  *
 377  * Before calling,
 378  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
 379  * are two extent state structs in the tree:
 380  * prealloc: [orig->start, split - 1]
 381  * orig: [ split, orig->end ]
 382  *
 383  * The tree locks are not taken by this function. They need to be held
 384  * by the caller.
 385  */
 386 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 387                        struct extent_state *prealloc, u64 split)
 388 {
 389         struct rb_node *node;
 390         prealloc->start = orig->start;
 391         prealloc->end = split - 1;
 392         prealloc->state = orig->state;
 393         orig->start = split;
 394
 395         node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node);
 396         if (node) {
 397                 struct extent_state *found;
 398                 found = rb_entry(node, struct extent_state, rb_node);
 399                 printk("found node %Lu %Lu on insert of %Lu %Lu\n", found->start, found->end, prealloc->start, prealloc->end);
 400                 free_extent_state(prealloc);
 401                 return -EEXIST;
 402         }
 403         prealloc->tree = tree;
 404         return 0;
 405 }
 406
 407 /*
 408  * utility function to clear some bits in an extent state struct.
 409  * it will optionally wake up any one waiting on this state (wake == 1), or
 410  * forcibly remove the state from the tree (delete == 1).
 411  *
 412  * If no bits are set on the state struct after clearing things, the
 413  * struct is freed and removed from the tree
 414  */
 415 static int clear_state_bit(struct extent_io_tree *tree,
 416                             struct extent_state *state, int bits, int wake,
 417                             int delete)
 418 {
 419         int ret = state->state & bits;
 420
 421         if ((bits & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
 422                 u64 range = state->end - state->start + 1;
 423                 WARN_ON(range > tree->dirty_bytes);
 424                 tree->dirty_bytes -= range;
 425         }
 426         clear_state_cb(tree, state, bits);
 427         state->state &= ~bits;
 428         if (wake)
 429                 wake_up(&state->wq);
 430         if (delete || state->state == 0) {
 431                 if (state->tree) {
 432                         clear_state_cb(tree, state, state->state);
 433                         rb_erase(&state->rb_node, &tree->state);
 434                         state->tree = NULL;
 435                         free_extent_state(state);
 436                 } else {
 437                         WARN_ON(1);
 438                 }
 439         } else {
 440                 merge_state(tree, state);
 441         }
 442         return ret;
 443 }
 444
 445 /*
 446  * clear some bits on a range in the tree.  This may require splitting
 447  * or inserting elements in the tree, so the gfp mask is used to
 448  * indicate which allocations or sleeping are allowed.
 449  *
 450  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
 451  * the given range from the tree regardless of state (ie for truncate).
 452  *
 453  * the range [start, end] is inclusive.
 454  *
 455  * This takes the tree lock, and returns < 0 on error, > 0 if any of the
 456  * bits were already set, or zero if none of the bits were already set.
 457  */
 458 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 459                      int bits, int wake, int delete, gfp_t mask)
 460 {
 461         struct extent_state *state;
 462         struct extent_state *prealloc = NULL;
 463         struct rb_node *node;
 464         unsigned long flags;
 465         int err;
 466         int set = 0;
 467
 468 again:
 469         if (!prealloc && (mask & __GFP_WAIT)) {
 470                 prealloc = alloc_extent_state(mask);
 471                 if (!prealloc)
 472                         return -ENOMEM;
 473         }
 474
 475         spin_lock_irqsave(&tree->lock, flags);
 476         /*
 477          * this search will find the extents that end after
 478          * our range starts
 479          */
 480         node = tree_search(tree, start);
 481         if (!node)
 482                 goto out;
 483         state = rb_entry(node, struct extent_state, rb_node);
 484         if (state->start > end)
 485                 goto out;
 486         WARN_ON(state->end < start);
 487
 488         /*
 489          *     | ---- desired range ---- |
 490          *  | state | or
 491          *  | ------------- state -------------- |
 492          *
 493          * We need to split the extent we found, and may flip
 494          * bits on second half.
 495          *
 496          * If the extent we found extends past our range, we
 497          * just split and search again.  It'll get split again
 498          * the next time though.
 499          *
 500          * If the extent we found is inside our range, we clear
 501          * the desired bit on it.
 502          */
 503
 504         if (state->start < start) {
 505                 if (!prealloc)
 506                         prealloc = alloc_extent_state(GFP_ATOMIC);
 507                 err = split_state(tree, state, prealloc, start);
 508                 BUG_ON(err == -EEXIST);
 509                 prealloc = NULL;
 510                 if (err)
 511                         goto out;
 512                 if (state->end <= end) {
 513                         start = state->end + 1;
 514                         set |= clear_state_bit(tree, state, bits,
 515                                         wake, delete);
 516                 } else {
 517                         start = state->start;
 518                 }
 519                 goto search_again;
 520         }
 521         /*
 522          * | ---- desired range ---- |
 523          *                        | state |
 524          * We need to split the extent, and clear the bit
 525          * on the first half
 526          */
 527         if (state->start <= end && state->end > end) {
 528                 if (!prealloc)
 529                         prealloc = alloc_extent_state(GFP_ATOMIC);
 530                 err = split_state(tree, state, prealloc, end + 1);
 531                 BUG_ON(err == -EEXIST);
 532
 533                 if (wake)
 534                         wake_up(&state->wq);
 535                 set |= clear_state_bit(tree, prealloc, bits,
 536                                        wake, delete);
 537                 prealloc = NULL;
 538                 goto out;
 539         }
 540
 541         start = state->end + 1;
 542         set |= clear_state_bit(tree, state, bits, wake, delete);
 543         goto search_again;
 544
 545 out:
 546         spin_unlock_irqrestore(&tree->lock, flags);
 547         if (prealloc)
 548                 free_extent_state(prealloc);
 549
 550         return set;
 551
 552 search_again:
 553         if (start > end)
 554                 goto out;
 555         spin_unlock_irqrestore(&tree->lock, flags);
 556         if (mask & __GFP_WAIT)
 557                 cond_resched();
 558         goto again;
 559 }
 560 EXPORT_SYMBOL(clear_extent_bit);
 561
 562 static int wait_on_state(struct extent_io_tree *tree,
 563                          struct extent_state *state)
 564 {
 565         DEFINE_WAIT(wait);
 566         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
 567         spin_unlock_irq(&tree->lock);
 568         schedule();
 569         spin_lock_irq(&tree->lock);
 570         finish_wait(&state->wq, &wait);
 571         return 0;
 572 }
 573
 574 /*
 575  * waits for one or more bits to clear on a range in the state tree.
 576  * The range [start, end] is inclusive.
 577  * The tree lock is taken by this function
 578  */
 579 int wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, int bits)
 580 {
 581         struct extent_state *state;
 582         struct rb_node *node;
 583
 584         spin_lock_irq(&tree->lock);
 585 again:
 586         while (1) {
 587                 /*
 588                  * this search will find all the extents that end after
 589                  * our range starts
 590                  */
 591                 node = tree_search(tree, start);
 592                 if (!node)
 593                         break;
 594
 595                 state = rb_entry(node, struct extent_state, rb_node);
 596
 597                 if (state->start > end)
 598                         goto out;
 599
 600                 if (state->state & bits) {
 601                         start = state->start;
 602                         atomic_inc(&state->refs);
 603                         wait_on_state(tree, state);
 604                         free_extent_state(state);
 605                         goto again;
 606                 }
 607                 start = state->end + 1;
 608
 609                 if (start > end)
 610                         break;
 611
 612                 if (need_resched()) {
 613                         spin_unlock_irq(&tree->lock);
 614                         cond_resched();
 615                         spin_lock_irq(&tree->lock);
 616                 }
 617         }
 618 out:
 619         spin_unlock_irq(&tree->lock);
 620         return 0;
 621 }
 622 EXPORT_SYMBOL(wait_extent_bit);
 623
 624 static void set_state_bits(struct extent_io_tree *tree,
 625                            struct extent_state *state,
 626                            int bits)
 627 {
 628         if ((bits & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
 629                 u64 range = state->end - state->start + 1;
 630                 tree->dirty_bytes += range;
 631         }
 632         set_state_cb(tree, state, bits);
 633         state->state |= bits;
 634 }
 635
 636 /*
 637  * set some bits on a range in the tree.  This may require allocations
 638  * or sleeping, so the gfp mask is used to indicate what is allowed.
 639  *
 640  * If 'exclusive' == 1, this will fail with -EEXIST if some part of the
 641  * range already has the desired bits set.  The start of the existing
 642  * range is returned in failed_start in this case.
 643  *
 644  * [start, end] is inclusive
 645  * This takes the tree lock.
 646  */
 647 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, int bits,
 648                    int exclusive, u64 *failed_start, gfp_t mask)
 649 {
 650         struct extent_state *state;
 651         struct extent_state *prealloc = NULL;
 652         struct rb_node *node;
 653         unsigned long flags;
 654         int err = 0;
 655         int set;
 656         u64 last_start;
 657         u64 last_end;
 658 again:
 659         if (!prealloc && (mask & __GFP_WAIT)) {
 660                 prealloc = alloc_extent_state(mask);
 661                 if (!prealloc)
 662                         return -ENOMEM;
 663         }
 664
 665         spin_lock_irqsave(&tree->lock, flags);
 666         /*
 667          * this search will find all the extents that end after
 668          * our range starts.
 669          */
 670         node = tree_search(tree, start);
 671         if (!node) {
 672                 err = insert_state(tree, prealloc, start, end, bits);
 673                 prealloc = NULL;
 674                 BUG_ON(err == -EEXIST);
 675                 goto out;
 676         }
 677
 678         state = rb_entry(node, struct extent_state, rb_node);
 679         last_start = state->start;
 680         last_end = state->end;
 681
 682         /*
 683          * | ---- desired range ---- |
 684          * | state |
 685          *
 686          * Just lock what we found and keep going
 687          */
 688         if (state->start == start && state->end <= end) {
 689                 set = state->state & bits;
 690                 if (set && exclusive) {
 691                         *failed_start = state->start;
 692                         err = -EEXIST;
 693                         goto out;
 694                 }
 695                 set_state_bits(tree, state, bits);
 696                 start = state->end + 1;
 697                 merge_state(tree, state);
 698                 goto search_again;
 699         }
 700
 701         /*
 702          *     | ---- desired range ---- |
 703          * | state |
 704          *   or
 705          * | ------------- state -------------- |
 706          *
 707          * We need to split the extent we found, and may flip bits on
 708          * second half.
 709          *
 710          * If the extent we found extends past our
 711          * range, we just split and search again.  It'll get split
 712          * again the next time though.
 713          *
 714          * If the extent we found is inside our range, we set the
 715          * desired bit on it.
 716          */
 717         if (state->start < start) {
 718                 set = state->state & bits;
 719                 if (exclusive && set) {
 720                         *failed_start = start;
 721                         err = -EEXIST;
 722                         goto out;
 723                 }
 724                 err = split_state(tree, state, prealloc, start);
 725                 BUG_ON(err == -EEXIST);
 726                 prealloc = NULL;
 727                 if (err)
 728                         goto out;
 729                 if (state->end <= end) {
 730                         set_state_bits(tree, state, bits);
 731                         start = state->end + 1;
 732                         merge_state(tree, state);
 733                 } else {
 734                         start = state->start;
 735                 }
 736                 goto search_again;
 737         }
 738         /*
 739          * | ---- desired range ---- |
 740          *     | state | or               | state |
 741          *
 742          * There's a hole, we need to insert something in it and
 743          * ignore the extent we found.
 744          */
 745         if (state->start > start) {
 746                 u64 this_end;
 747                 if (end < last_start)
 748                         this_end = end;
 749                 else
 750                         this_end = last_start -1;
 751                 err = insert_state(tree, prealloc, start, this_end,
 752                                    bits);
 753                 prealloc = NULL;
 754                 BUG_ON(err == -EEXIST);
 755                 if (err)
 756                         goto out;
 757                 start = this_end + 1;
 758                 goto search_again;
 759         }
 760         /*
 761          * | ---- desired range ---- |
 762          *                        | state |
 763          * We need to split the extent, and set the bit
 764          * on the first half
 765          */
 766         if (state->start <= end && state->end > end) {
 767                 set = state->state & bits;
 768                 if (exclusive && set) {
 769                         *failed_start = start;
 770                         err = -EEXIST;
 771                         goto out;
 772                 }
 773                 err = split_state(tree, state, prealloc, end + 1);
 774                 BUG_ON(err == -EEXIST);
 775
 776                 set_state_bits(tree, prealloc, bits);
 777                 merge_state(tree, prealloc);
 778                 prealloc = NULL;
 779                 goto out;
 780         }
 781
 782         goto search_again;
 783
 784 out:
 785         spin_unlock_irqrestore(&tree->lock, flags);
 786         if (prealloc)
 787                 free_extent_state(prealloc);
 788
 789         return err;
 790
 791 search_again:
 792         if (start > end)
 793                 goto out;
 794         spin_unlock_irqrestore(&tree->lock, flags);
 795         if (mask & __GFP_WAIT)
 796                 cond_resched();
 797         goto again;
 798 }
 799 EXPORT_SYMBOL(set_extent_bit);
 800
 801 /* wrappers around set/clear extent bit */
 802 int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
 803                      gfp_t mask)
 804 {
 805         return set_extent_bit(tree, start, end, EXTENT_DIRTY, 0, NULL,
 806                               mask);
 807 }
 808 EXPORT_SYMBOL(set_extent_dirty);
 809
 810 int set_extent_ordered(struct extent_io_tree *tree, u64 start, u64 end,
 811                        gfp_t mask)
 812 {
 813         return set_extent_bit(tree, start, end, EXTENT_ORDERED, 0, NULL, mask);
 814 }
 815 EXPORT_SYMBOL(set_extent_ordered);
 816
 817 int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 818                     int bits, gfp_t mask)
 819 {
 820         return set_extent_bit(tree, start, end, bits, 0, NULL,
 821                               mask);
 822 }
 823 EXPORT_SYMBOL(set_extent_bits);
 824
 825 int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 826                       int bits, gfp_t mask)
 827 {
 828         return clear_extent_bit(tree, start, end, bits, 0, 0, mask);
 829 }
 830 EXPORT_SYMBOL(clear_extent_bits);
 831
 832 int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
 833                      gfp_t mask)
 834 {
 835         return set_extent_bit(tree, start, end,
 836                               EXTENT_DELALLOC | EXTENT_DIRTY,
 837                               0, NULL, mask);
 838 }
 839 EXPORT_SYMBOL(set_extent_delalloc);
 840
 841 int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
 842                        gfp_t mask)
 843 {
 844         return clear_extent_bit(tree, start, end,
 845                                 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, mask);
 846 }
 847 EXPORT_SYMBOL(clear_extent_dirty);
 848
 849 int clear_extent_ordered(struct extent_io_tree *tree, u64 start, u64 end,
 850                          gfp_t mask)
 851 {
 852         return clear_extent_bit(tree, start, end, EXTENT_ORDERED, 1, 0, mask);
 853 }
 854 EXPORT_SYMBOL(clear_extent_ordered);
 855
 856 int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
 857                      gfp_t mask)
 858 {
 859         return set_extent_bit(tree, start, end, EXTENT_NEW, 0, NULL,
 860                               mask);
 861 }
 862 EXPORT_SYMBOL(set_extent_new);
 863
 864 int clear_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
 865                        gfp_t mask)
 866 {
 867         return clear_extent_bit(tree, start, end, EXTENT_NEW, 0, 0, mask);
 868 }
 869 EXPORT_SYMBOL(clear_extent_new);
 870
 871 int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
 872                         gfp_t mask)
 873 {
 874         return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL,
 875                               mask);
 876 }
 877 EXPORT_SYMBOL(set_extent_uptodate);
 878
 879 int clear_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
 880                           gfp_t mask)
 881 {
 882         return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0, mask);
 883 }
 884 EXPORT_SYMBOL(clear_extent_uptodate);
 885
 886 int set_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end,
 887                          gfp_t mask)
 888 {
 889         return set_extent_bit(tree, start, end, EXTENT_WRITEBACK,
 890                               0, NULL, mask);
 891 }
 892 EXPORT_SYMBOL(set_extent_writeback);
 893
 894 int clear_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end,
 895                            gfp_t mask)
 896 {
 897         return clear_extent_bit(tree, start, end, EXTENT_WRITEBACK, 1, 0, mask);
 898 }
 899 EXPORT_SYMBOL(clear_extent_writeback);
 900
 901 int wait_on_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end)
 902 {
 903         return wait_extent_bit(tree, start, end, EXTENT_WRITEBACK);
 904 }
 905 EXPORT_SYMBOL(wait_on_extent_writeback);
 906
 907 int lock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask)
 908 {
 909         int err;
 910         u64 failed_start;
 911         while (1) {
 912                 err = set_extent_bit(tree, start, end, EXTENT_LOCKED, 1,
 913                                      &failed_start, mask);
 914                 if (err == -EEXIST && (mask & __GFP_WAIT)) {
 915                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
 916                         start = failed_start;
 917                 } else {
 918                         break;
 919                 }
 920                 WARN_ON(start > end);
 921         }
 922         return err;
 923 }
 924 EXPORT_SYMBOL(lock_extent);
 925
 926 int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end,
 927                   gfp_t mask)
 928 {
 929         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, mask);
 930 }
 931 EXPORT_SYMBOL(unlock_extent);
 932
 933 /*
 934  * helper function to set pages and extents in the tree dirty
 935  */
 936 int set_range_dirty(struct extent_io_tree *tree, u64 start, u64 end)
 937 {
 938         unsigned long index = start >> PAGE_CACHE_SHIFT;
 939         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
 940         struct page *page;
 941
 942         while (index <= end_index) {
 943                 page = find_get_page(tree->mapping, index);
 944                 BUG_ON(!page);
 945                 __set_page_dirty_nobuffers(page);
 946                 page_cache_release(page);
 947                 index++;
 948         }
 949         set_extent_dirty(tree, start, end, GFP_NOFS);
 950         return 0;
 951 }
 952 EXPORT_SYMBOL(set_range_dirty);
 953
 954 /*
 955  * helper function to set both pages and extents in the tree writeback
 956  */
 957 int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
 958 {
 959         unsigned long index = start >> PAGE_CACHE_SHIFT;
 960         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
 961         struct page *page;
 962
 963         while (index <= end_index) {
 964                 page = find_get_page(tree->mapping, index);
 965                 BUG_ON(!page);
 966                 set_page_writeback(page);
 967                 page_cache_release(page);
 968                 index++;
 969         }
 970         set_extent_writeback(tree, start, end, GFP_NOFS);
 971         return 0;
 972 }
 973 EXPORT_SYMBOL(set_range_writeback);
 974
 975 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
 976                           u64 *start_ret, u64 *end_ret, int bits)
 977 {
 978         struct rb_node *node;
 979         struct extent_state *state;
 980         int ret = 1;
 981
 982         spin_lock_irq(&tree->lock);
 983         /*
 984          * this search will find all the extents that end after
 985          * our range starts.
 986          */
 987         node = tree_search(tree, start);
 988         if (!node) {
 989                 goto out;
 990         }
 991
 992         while(1) {
 993                 state = rb_entry(node, struct extent_state, rb_node);
 994                 if (state->end >= start && (state->state & bits)) {
 995                         *start_ret = state->start;
 996                         *end_ret = state->end;
 997                         ret = 0;
 998                         break;
 999                 }
1000                 node = rb_next(node);
1001                 if (!node)
1002                         break;
1003         }
1004 out:
1005         spin_unlock_irq(&tree->lock);
1006         return ret;
1007 }
1008 EXPORT_SYMBOL(find_first_extent_bit);
1009
1010 struct extent_state *find_first_extent_bit_state(struct extent_io_tree *tree,
1011                                                  u64 start, int bits)
1012 {
1013         struct rb_node *node;
1014         struct extent_state *state;
1015
1016         /*
1017          * this search will find all the extents that end after
1018          * our range starts.
1019          */
1020         node = tree_search(tree, start);
1021         if (!node) {
1022                 goto out;
1023         }
1024
1025         while(1) {
1026                 state = rb_entry(node, struct extent_state, rb_node);
1027                 if (state->end >= start && (state->state & bits)) {
1028                         return state;
1029                 }
1030                 node = rb_next(node);
1031                 if (!node)
1032                         break;
1033         }
1034 out:
1035         return NULL;
1036 }
1037 EXPORT_SYMBOL(find_first_extent_bit_state);
1038
1039 u64 find_lock_delalloc_range(struct extent_io_tree *tree,
1040                              u64 *start, u64 *end, u64 max_bytes)
1041 {
1042         struct rb_node *node;
1043         struct extent_state *state;
1044         u64 cur_start = *start;
1045         u64 found = 0;
1046         u64 total_bytes = 0;
1047
1048         spin_lock_irq(&tree->lock);
1049         /*
1050          * this search will find all the extents that end after
1051          * our range starts.
1052          */
1053 search_again:
1054         node = tree_search(tree, cur_start);
1055         if (!node) {
1056                 if (!found)
1057                         *end = (u64)-1;
1058                 goto out;
1059         }
1060
1061         while(1) {
1062                 state = rb_entry(node, struct extent_state, rb_node);
1063                 if (found && state->start != cur_start) {
1064                         goto out;
1065                 }
1066                 if (!(state->state & EXTENT_DELALLOC)) {
1067                         if (!found)
1068                                 *end = state->end;
1069                         goto out;
1070                 }
1071                 if (!found) {
1072                         struct extent_state *prev_state;
1073                         struct rb_node *prev_node = node;
1074                         while(1) {
1075                                 prev_node = rb_prev(prev_node);
1076                                 if (!prev_node)
1077                                         break;
1078                                 prev_state = rb_entry(prev_node,
1079                                                       struct extent_state,
1080                                                       rb_node);
1081                                 if (!(prev_state->state & EXTENT_DELALLOC))
1082                                         break;
1083                                 state = prev_state;
1084                                 node = prev_node;
1085                         }
1086                 }
1087                 if (state->state & EXTENT_LOCKED) {
1088                         DEFINE_WAIT(wait);
1089                         atomic_inc(&state->refs);
1090                         prepare_to_wait(&state->wq, &wait,
1091                                         TASK_UNINTERRUPTIBLE);
1092                         spin_unlock_irq(&tree->lock);
1093                         schedule();
1094                         spin_lock_irq(&tree->lock);
1095                         finish_wait(&state->wq, &wait);
1096                         free_extent_state(state);
1097                         goto search_again;
1098                 }
1099                 set_state_cb(tree, state, EXTENT_LOCKED);
1100                 state->state |= EXTENT_LOCKED;
1101                 if (!found)
1102                         *start = state->start;
1103                 found++;
1104                 *end = state->end;
1105                 cur_start = state->end + 1;
1106                 node = rb_next(node);
1107                 if (!node)
1108                         break;
1109                 total_bytes += state->end - state->start + 1;
1110                 if (total_bytes >= max_bytes)
1111                         break;
1112         }
1113 out:
1114         spin_unlock_irq(&tree->lock);
1115         return found;
1116 }
1117
1118 u64 count_range_bits(struct extent_io_tree *tree,
1119                      u64 *start, u64 search_end, u64 max_bytes,
1120                      unsigned long bits)
1121 {
1122         struct rb_node *node;
1123         struct extent_state *state;
1124         u64 cur_start = *start;
1125         u64 total_bytes = 0;
1126         int found = 0;
1127
1128         if (search_end <= cur_start) {
1129                 printk("search_end %Lu start %Lu\n", search_end, cur_start);
1130                 WARN_ON(1);
1131                 return 0;
1132         }
1133
1134         spin_lock_irq(&tree->lock);
1135         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1136                 total_bytes = tree->dirty_bytes;
1137                 goto out;
1138         }
1139         /*
1140          * this search will find all the extents that end after
1141          * our range starts.
1142          */
1143         node = tree_search(tree, cur_start);
1144         if (!node) {
1145                 goto out;
1146         }
1147
1148         while(1) {
1149                 state = rb_entry(node, struct extent_state, rb_node);
1150                 if (state->start > search_end)
1151                         break;
1152                 if (state->end >= cur_start && (state->state & bits)) {
1153                         total_bytes += min(search_end, state->end) + 1 -
1154                                        max(cur_start, state->start);
1155                         if (total_bytes >= max_bytes)
1156                                 break;
1157                         if (!found) {
1158                                 *start = state->start;
1159                                 found = 1;
1160                         }
1161                 }
1162                 node = rb_next(node);
1163                 if (!node)
1164                         break;
1165         }
1166 out:
1167         spin_unlock_irq(&tree->lock);
1168         return total_bytes;
1169 }
1170 /*
1171  * helper function to lock both pages and extents in the tree.
1172  * pages must be locked first.
1173  */
1174 int lock_range(struct extent_io_tree *tree, u64 start, u64 end)
1175 {
1176         unsigned long index = start >> PAGE_CACHE_SHIFT;
1177         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1178         struct page *page;
1179         int err;
1180
1181         while (index <= end_index) {
1182                 page = grab_cache_page(tree->mapping, index);
1183                 if (!page) {
1184                         err = -ENOMEM;
1185                         goto failed;
1186                 }
1187                 if (IS_ERR(page)) {
1188                         err = PTR_ERR(page);
1189                         goto failed;
1190                 }
1191                 index++;
1192         }
1193         lock_extent(tree, start, end, GFP_NOFS);
1194         return 0;
1195
1196 failed:
1197         /*
1198          * we failed above in getting the page at 'index', so we undo here
1199          * up to but not including the page at 'index'
1200          */
1201         end_index = index;
1202         index = start >> PAGE_CACHE_SHIFT;
1203         while (index < end_index) {
1204                 page = find_get_page(tree->mapping, index);
1205                 unlock_page(page);
1206                 page_cache_release(page);
1207                 index++;
1208         }
1209         return err;
1210 }
1211 EXPORT_SYMBOL(lock_range);
1212
1213 /*
1214  * helper function to unlock both pages and extents in the tree.
1215  */
1216 int unlock_range(struct extent_io_tree *tree, u64 start, u64 end)
1217 {
1218         unsigned long index = start >> PAGE_CACHE_SHIFT;
1219         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1220         struct page *page;
1221
1222         while (index <= end_index) {
1223                 page = find_get_page(tree->mapping, index);
1224                 unlock_page(page);
1225                 page_cache_release(page);
1226                 index++;
1227         }
1228         unlock_extent(tree, start, end, GFP_NOFS);
1229         return 0;
1230 }
1231 EXPORT_SYMBOL(unlock_range);
1232
1233 int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
1234 {
1235         struct rb_node *node;
1236         struct extent_state *state;
1237         int ret = 0;
1238
1239         spin_lock_irq(&tree->lock);
1240         /*
1241          * this search will find all the extents that end after
1242          * our range starts.
1243          */
1244         node = tree_search(tree, start);
1245         if (!node) {
1246                 ret = -ENOENT;
1247                 goto out;
1248         }
1249         state = rb_entry(node, struct extent_state, rb_node);
1250         if (state->start != start) {
1251                 ret = -ENOENT;
1252                 goto out;
1253         }
1254         state->private = private;
1255 out:
1256         spin_unlock_irq(&tree->lock);
1257         return ret;
1258 }
1259
1260 int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
1261 {
1262         struct rb_node *node;
1263         struct extent_state *state;
1264         int ret = 0;
1265
1266         spin_lock_irq(&tree->lock);
1267         /*
1268          * this search will find all the extents that end after
1269          * our range starts.
1270          */
1271         node = tree_search(tree, start);
1272         if (!node) {
1273                 ret = -ENOENT;
1274                 goto out;
1275         }
1276         state = rb_entry(node, struct extent_state, rb_node);
1277         if (state->start != start) {
1278                 ret = -ENOENT;
1279                 goto out;
1280         }
1281         *private = state->private;
1282 out:
1283         spin_unlock_irq(&tree->lock);
1284         return ret;
1285 }
1286
1287 /*
1288  * searches a range in the state tree for a given mask.
1289  * If 'filled' == 1, this returns 1 only if every extent in the tree
1290  * has the bits set.  Otherwise, 1 is returned if any bit in the
1291  * range is found set.
1292  */
1293 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
1294                    int bits, int filled)
1295 {
1296         struct extent_state *state = NULL;
1297         struct rb_node *node;
1298         int bitset = 0;
1299         unsigned long flags;
1300
1301         spin_lock_irqsave(&tree->lock, flags);
1302         node = tree_search(tree, start);
1303         while (node && start <= end) {
1304                 state = rb_entry(node, struct extent_state, rb_node);
1305
1306                 if (filled && state->start > start) {
1307                         bitset = 0;
1308                         break;
1309                 }
1310
1311                 if (state->start > end)
1312                         break;
1313
1314                 if (state->state & bits) {
1315                         bitset = 1;
1316                         if (!filled)
1317                                 break;
1318                 } else if (filled) {
1319                         bitset = 0;
1320                         break;
1321                 }
1322                 start = state->end + 1;
1323                 if (start > end)
1324                         break;
1325                 node = rb_next(node);
1326                 if (!node) {
1327                         if (filled)
1328                                 bitset = 0;
1329                         break;
1330                 }
1331         }
1332         spin_unlock_irqrestore(&tree->lock, flags);
1333         return bitset;
1334 }
1335 EXPORT_SYMBOL(test_range_bit);
1336
1337 /*
1338  * helper function to set a given page up to date if all the
1339  * extents in the tree for that page are up to date
1340  */
1341 static int check_page_uptodate(struct extent_io_tree *tree,
1342                                struct page *page)
1343 {
1344         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1345         u64 end = start + PAGE_CACHE_SIZE - 1;
1346         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1))
1347                 SetPageUptodate(page);
1348         return 0;
1349 }
1350
1351 /*
1352  * helper function to unlock a page if all the extents in the tree
1353  * for that page are unlocked
1354  */
1355 static int check_page_locked(struct extent_io_tree *tree,
1356                              struct page *page)
1357 {
1358         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1359         u64 end = start + PAGE_CACHE_SIZE - 1;
1360         if (!test_range_bit(tree, start, end, EXTENT_LOCKED, 0))
1361                 unlock_page(page);
1362         return 0;
1363 }
1364
1365 /*
1366  * helper function to end page writeback if all the extents
1367  * in the tree for that page are done with writeback
1368  */
1369 static int check_page_writeback(struct extent_io_tree *tree,
1370                              struct page *page)
1371 {
1372         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1373         u64 end = start + PAGE_CACHE_SIZE - 1;
1374         if (!test_range_bit(tree, start, end, EXTENT_WRITEBACK, 0))
1375                 end_page_writeback(page);
1376         return 0;
1377 }
1378
1379 /* lots and lots of room for performance fixes in the end_bio funcs */
1380
1381 /*
1382  * after a writepage IO is done, we need to:
1383  * clear the uptodate bits on error
1384  * clear the writeback bits in the extent tree for this IO
1385  * end_page_writeback if the page has no more pending IO
1386  *
1387  * Scheduling is not allowed, so the extent state tree is expected
1388  * to have one and only one object corresponding to this IO.
1389  */
1390 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1391 static void end_bio_extent_writepage(struct bio *bio, int err)
1392 #else
1393 static int end_bio_extent_writepage(struct bio *bio,
1394                                    unsigned int bytes_done, int err)
1395 #endif
1396 {
1397         int uptodate = err == 0;
1398         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1399         struct extent_io_tree *tree;
1400         u64 start;
1401         u64 end;
1402         int whole_page;
1403         int ret;
1404
1405 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1406         if (bio->bi_size)
1407                 return 1;
1408 #endif
1409         do {
1410                 struct page *page = bvec->bv_page;
1411                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1412
1413                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1414                          bvec->bv_offset;
1415                 end = start + bvec->bv_len - 1;
1416
1417                 if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
1418                         whole_page = 1;
1419                 else
1420                         whole_page = 0;
1421
1422                 if (--bvec >= bio->bi_io_vec)
1423                         prefetchw(&bvec->bv_page->flags);
1424                 if (tree->ops && tree->ops->writepage_end_io_hook) {
1425                         ret = tree->ops->writepage_end_io_hook(page, start,
1426                                                        end, NULL, uptodate);
1427                         if (ret)
1428                                 uptodate = 0;
1429                 }
1430
1431                 if (!uptodate && tree->ops &&
1432                     tree->ops->writepage_io_failed_hook) {
1433                         ret = tree->ops->writepage_io_failed_hook(bio, page,
1434                                                          start, end, NULL);
1435                         if (ret == 0) {
1436                                 uptodate = (err == 0);
1437                                 continue;
1438                         }
1439                 }
1440
1441                 if (!uptodate) {
1442                         clear_extent_uptodate(tree, start, end, GFP_ATOMIC);
1443                         ClearPageUptodate(page);
1444                         SetPageError(page);
1445                 }
1446
1447                 clear_extent_writeback(tree, start, end, GFP_ATOMIC);
1448
1449                 if (whole_page)
1450                         end_page_writeback(page);
1451                 else
1452                         check_page_writeback(tree, page);
1453         } while (bvec >= bio->bi_io_vec);
1454         bio_put(bio);
1455 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1456         return 0;
1457 #endif
1458 }
1459
1460 /*
1461  * after a readpage IO is done, we need to:
1462  * clear the uptodate bits on error
1463  * set the uptodate bits if things worked
1464  * set the page up to date if all extents in the tree are uptodate
1465  * clear the lock bit in the extent tree
1466  * unlock the page if there are no other extents locked for it
1467  *
1468  * Scheduling is not allowed, so the extent state tree is expected
1469  * to have one and only one object corresponding to this IO.
1470  */
1471 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1472 static void end_bio_extent_readpage(struct bio *bio, int err)
1473 #else
1474 static int end_bio_extent_readpage(struct bio *bio,
1475                                    unsigned int bytes_done, int err)
1476 #endif
1477 {
1478         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1479         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1480         struct extent_io_tree *tree;
1481         u64 start;
1482         u64 end;
1483         int whole_page;
1484         int ret;
1485
1486 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1487         if (bio->bi_size)
1488                 return 1;
1489 #endif
1490
1491         do {
1492                 struct page *page = bvec->bv_page;
1493                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1494
1495                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1496                         bvec->bv_offset;
1497                 end = start + bvec->bv_len - 1;
1498
1499                 if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
1500                         whole_page = 1;
1501                 else
1502                         whole_page = 0;
1503
1504                 if (--bvec >= bio->bi_io_vec)
1505                         prefetchw(&bvec->bv_page->flags);
1506
1507                 if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
1508                         ret = tree->ops->readpage_end_io_hook(page, start, end,
1509                                                               NULL);
1510                         if (ret)
1511                                 uptodate = 0;
1512                 }
1513                 if (!uptodate && tree->ops &&
1514                     tree->ops->readpage_io_failed_hook) {
1515                         ret = tree->ops->readpage_io_failed_hook(bio, page,
1516                                                          start, end, NULL);
1517                         if (ret == 0) {
1518                                 uptodate =
1519                                         test_bit(BIO_UPTODATE, &bio->bi_flags);
1520                                 continue;
1521                         }
1522                 }
1523
1524                 if (uptodate)
1525                         set_extent_uptodate(tree, start, end,
1526                                             GFP_ATOMIC);
1527                 unlock_extent(tree, start, end, GFP_ATOMIC);
1528
1529                 if (whole_page) {
1530                         if (uptodate) {
1531                                 SetPageUptodate(page);
1532                         } else {
1533                                 ClearPageUptodate(page);
1534                                 SetPageError(page);
1535                         }
1536                         unlock_page(page);
1537                 } else {
1538                         if (uptodate) {
1539                                 check_page_uptodate(tree, page);
1540                         } else {
1541                                 ClearPageUptodate(page);
1542                                 SetPageError(page);
1543                         }
1544                         check_page_locked(tree, page);
1545                 }
1546         } while (bvec >= bio->bi_io_vec);
1547
1548         bio_put(bio);
1549 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1550         return 0;
1551 #endif
1552 }
1553
1554 /*
1555  * IO done from prepare_write is pretty simple, we just unlock
1556  * the structs in the extent tree when done, and set the uptodate bits
1557  * as appropriate.
1558  */
1559 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
1560 static void end_bio_extent_preparewrite(struct bio *bio, int err)
1561 #else
1562 static int end_bio_extent_preparewrite(struct bio *bio,
1563                                        unsigned int bytes_done, int err)
1564 #endif
1565 {
1566         const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1567         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1568         struct extent_io_tree *tree;
1569         u64 start;
1570         u64 end;
1571
1572 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1573         if (bio->bi_size)
1574                 return 1;
1575 #endif
1576
1577         do {
1578                 struct page *page = bvec->bv_page;
1579                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1580
1581                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1582                         bvec->bv_offset;
1583                 end = start + bvec->bv_len - 1;
1584
1585                 if (--bvec >= bio->bi_io_vec)
1586                         prefetchw(&bvec->bv_page->flags);
1587
1588                 if (uptodate) {
1589                         set_extent_uptodate(tree, start, end, GFP_ATOMIC);
1590                 } else {
1591                         ClearPageUptodate(page);
1592                         SetPageError(page);
1593                 }
1594
1595                 unlock_extent(tree, start, end, GFP_ATOMIC);
1596
1597         } while (bvec >= bio->bi_io_vec);
1598
1599         bio_put(bio);
1600 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
1601         return 0;
1602 #endif
1603 }
1604
1605 static struct bio *
1606 extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
1607                  gfp_t gfp_flags)
1608 {
1609         struct bio *bio;
1610
1611         bio = bio_alloc(gfp_flags, nr_vecs);
1612
1613         if (bio == NULL && (current->flags & PF_MEMALLOC)) {
1614                 while (!bio && (nr_vecs /= 2))
1615                         bio = bio_alloc(gfp_flags, nr_vecs);
1616         }
1617
1618         if (bio) {
1619                 bio->bi_size = 0;
1620                 bio->bi_bdev = bdev;
1621                 bio->bi_sector = first_sector;
1622         }
1623         return bio;
1624 }
1625
1626 static int submit_one_bio(int rw, struct bio *bio, int mirror_num)
1627 {
1628         int ret = 0;
1629         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1630         struct page *page = bvec->bv_page;
1631         struct extent_io_tree *tree = bio->bi_private;
1632         struct rb_node *node;
1633         struct extent_state *state;
1634         u64 start;
1635         u64 end;
1636
1637         start = ((u64)page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset;
1638         end = start + bvec->bv_len - 1;
1639
1640         spin_lock_irq(&tree->lock);
1641         node = __etree_search(tree, start, NULL, NULL);
1642         BUG_ON(!node);
1643         state = rb_entry(node, struct extent_state, rb_node);
1644         while(state->end < end) {
1645                 node = rb_next(node);
1646                 state = rb_entry(node, struct extent_state, rb_node);
1647         }
1648         BUG_ON(state->end != end);
1649         spin_unlock_irq(&tree->lock);
1650
1651         bio->bi_private = NULL;
1652
1653         bio_get(bio);
1654
1655         if (tree->ops && tree->ops->submit_bio_hook)
1656                 tree->ops->submit_bio_hook(page->mapping->host, rw, bio,
1657                                            mirror_num);
1658         else
1659                 submit_bio(rw, bio);
1660         if (bio_flagged(bio, BIO_EOPNOTSUPP))
1661                 ret = -EOPNOTSUPP;
1662         bio_put(bio);
1663         return ret;
1664 }
1665
1666 static int submit_extent_page(int rw, struct extent_io_tree *tree,
1667                               struct page *page, sector_t sector,
1668                               size_t size, unsigned long offset,
1669                               struct block_device *bdev,
1670                               struct bio **bio_ret,
1671                               unsigned long max_pages,
1672                               bio_end_io_t end_io_func,
1673                               int mirror_num)
1674 {
1675         int ret = 0;
1676         struct bio *bio;
1677         int nr;
1678
1679         if (bio_ret && *bio_ret) {
1680                 bio = *bio_ret;
1681                 if (bio->bi_sector + (bio->bi_size >> 9) != sector ||
1682                     (tree->ops && tree->ops->merge_bio_hook &&
1683                      tree->ops->merge_bio_hook(page, offset, size, bio)) ||
1684                     bio_add_page(bio, page, size, offset) < size) {
1685                         ret = submit_one_bio(rw, bio, mirror_num);
1686                         bio = NULL;
1687                 } else {
1688                         return 0;
1689                 }
1690         }
1691         nr = bio_get_nr_vecs(bdev);
1692         bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
1693         if (!bio) {
1694                 printk("failed to allocate bio nr %d\n", nr);
1695         }
1696
1697
1698         bio_add_page(bio, page, size, offset);
1699         bio->bi_end_io = end_io_func;
1700         bio->bi_private = tree;
1701
1702         if (bio_ret) {
1703                 *bio_ret = bio;
1704         } else {
1705                 ret = submit_one_bio(rw, bio, mirror_num);
1706         }
1707
1708         return ret;
1709 }
1710
1711 void set_page_extent_mapped(struct page *page)
1712 {
1713         if (!PagePrivate(page)) {
1714                 SetPagePrivate(page);
1715                 page_cache_get(page);
1716                 set_page_private(page, EXTENT_PAGE_PRIVATE);
1717         }
1718 }
1719
1720 void set_page_extent_head(struct page *page, unsigned long len)
1721 {
1722         set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2);
1723 }
1724
1725 /*
1726  * basic readpage implementation.  Locked extent state structs are inserted
1727  * into the tree that are removed when the IO is done (by the end_io
1728  * handlers)
1729  */
1730 static int __extent_read_full_page(struct extent_io_tree *tree,
1731                                    struct page *page,
1732                                    get_extent_t *get_extent,
1733                                    struct bio **bio, int mirror_num)
1734 {
1735         struct inode *inode = page->mapping->host;
1736         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1737         u64 page_end = start + PAGE_CACHE_SIZE - 1;
1738         u64 end;
1739         u64 cur = start;
1740         u64 extent_offset;
1741         u64 last_byte = i_size_read(inode);
1742         u64 block_start;
1743         u64 cur_end;
1744         sector_t sector;
1745         struct extent_map *em;
1746         struct block_device *bdev;
1747         int ret;
1748         int nr = 0;
1749         size_t page_offset = 0;
1750         size_t iosize;
1751         size_t blocksize = inode->i_sb->s_blocksize;
1752
1753         set_page_extent_mapped(page);
1754
1755         end = page_end;
1756         lock_extent(tree, start, end, GFP_NOFS);
1757
1758         while (cur <= end) {
1759                 if (cur >= last_byte) {
1760                         char *userpage;
1761                         iosize = PAGE_CACHE_SIZE - page_offset;
1762                         userpage = kmap_atomic(page, KM_USER0);
1763                         memset(userpage + page_offset, 0, iosize);
1764                         flush_dcache_page(page);
1765                         kunmap_atomic(userpage, KM_USER0);
1766                         set_extent_uptodate(tree, cur, cur + iosize - 1,
1767                                             GFP_NOFS);
1768                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
1769                         break;
1770                 }
1771                 em = get_extent(inode, page, page_offset, cur,
1772                                 end - cur + 1, 0);
1773                 if (IS_ERR(em) || !em) {
1774                         SetPageError(page);
1775                         unlock_extent(tree, cur, end, GFP_NOFS);
1776                         break;
1777                 }
1778                 extent_offset = cur - em->start;
1779                 if (extent_map_end(em) <= cur) {
1780 printk("bad mapping em [%Lu %Lu] cur %Lu\n", em->start, extent_map_end(em), cur);
1781                 }
1782                 BUG_ON(extent_map_end(em) <= cur);
1783                 if (end < cur) {
1784 printk("2bad mapping end %Lu cur %Lu\n", end, cur);
1785                 }
1786                 BUG_ON(end < cur);
1787
1788                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
1789                 cur_end = min(extent_map_end(em) - 1, end);
1790                 iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
1791                 sector = (em->block_start + extent_offset) >> 9;
1792                 bdev = em->bdev;
1793                 block_start = em->block_start;
1794                 free_extent_map(em);
1795                 em = NULL;
1796
1797                 /* we've found a hole, just zero and go on */
1798                 if (block_start == EXTENT_MAP_HOLE) {
1799                         char *userpage;
1800                         userpage = kmap_atomic(page, KM_USER0);
1801                         memset(userpage + page_offset, 0, iosize);
1802                         flush_dcache_page(page);
1803                         kunmap_atomic(userpage, KM_USER0);
1804
1805                         set_extent_uptodate(tree, cur, cur + iosize - 1,
1806                                             GFP_NOFS);
1807                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
1808                         cur = cur + iosize;
1809                         page_offset += iosize;
1810                         continue;
1811                 }
1812                 /* the get_extent function already copied into the page */
1813                 if (test_range_bit(tree, cur, cur_end, EXTENT_UPTODATE, 1)) {
1814                         check_page_uptodate(tree, page);
1815                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
1816                         cur = cur + iosize;
1817                         page_offset += iosize;
1818                         continue;
1819                 }
1820                 /* we have an inline extent but it didn't get marked up
1821                  * to date.  Error out
1822                  */
1823                 if (block_start == EXTENT_MAP_INLINE) {
1824                         SetPageError(page);
1825                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
1826                         cur = cur + iosize;
1827                         page_offset += iosize;
1828                         continue;
1829                 }
1830
1831                 ret = 0;
1832                 if (tree->ops && tree->ops->readpage_io_hook) {
1833                         ret = tree->ops->readpage_io_hook(page, cur,
1834                                                           cur + iosize - 1);
1835                 }
1836                 if (!ret) {
1837                         unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
1838                         pnr -= page->index;
1839                         ret = submit_extent_page(READ, tree, page,
1840                                          sector, iosize, page_offset,
1841                                          bdev, bio, pnr,
1842                                          end_bio_extent_readpage, mirror_num);
1843                         nr++;
1844                 }
1845                 if (ret)
1846                         SetPageError(page);
1847                 cur = cur + iosize;
1848                 page_offset += iosize;
1849         }
1850         if (!nr) {
1851                 if (!PageError(page))
1852                         SetPageUptodate(page);
1853                 unlock_page(page);
1854         }
1855         return 0;
1856 }
1857
1858 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
1859                             get_extent_t *get_extent)
1860 {
1861         struct bio *bio = NULL;
1862         int ret;
1863
1864         ret = __extent_read_full_page(tree, page, get_extent, &bio, 0);
1865         if (bio)
1866                 submit_one_bio(READ, bio, 0);
1867         return ret;
1868 }
1869 EXPORT_SYMBOL(extent_read_full_page);
1870
1871 /*
1872  * the writepage semantics are similar to regular writepage.  extent
1873  * records are inserted to lock ranges in the tree, and as dirty areas
1874  * are found, they are marked writeback.  Then the lock bits are removed
1875  * and the end_io handler clears the writeback ranges
1876  */
1877 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
1878                               void *data)
1879 {
1880         struct inode *inode = page->mapping->host;
1881         struct extent_page_data *epd = data;
1882         struct extent_io_tree *tree = epd->tree;
1883         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1884         u64 delalloc_start;
1885         u64 page_end = start + PAGE_CACHE_SIZE - 1;
1886         u64 end;
1887         u64 cur = start;
1888         u64 extent_offset;
1889         u64 last_byte = i_size_read(inode);
1890         u64 block_start;
1891         u64 iosize;
1892         u64 unlock_start;
1893         sector_t sector;
1894         struct extent_map *em;
1895         struct block_device *bdev;
1896         int ret;
1897         int nr = 0;
1898         size_t pg_offset = 0;
1899         size_t blocksize;
1900         loff_t i_size = i_size_read(inode);
1901         unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
1902         u64 nr_delalloc;
1903         u64 delalloc_end;
1904
1905         WARN_ON(!PageLocked(page));
1906         pg_offset = i_size & (PAGE_CACHE_SIZE - 1);
1907         if (page->index > end_index ||
1908            (page->index == end_index && !pg_offset)) {
1909                 page->mapping->a_ops->invalidatepage(page, 0);
1910                 unlock_page(page);
1911                 return 0;
1912         }
1913
1914         if (page->index == end_index) {
1915                 char *userpage;
1916
1917                 userpage = kmap_atomic(page, KM_USER0);
1918                 memset(userpage + pg_offset, 0,
1919                        PAGE_CACHE_SIZE - pg_offset);
1920                 kunmap_atomic(userpage, KM_USER0);
1921                 flush_dcache_page(page);
1922         }
1923         pg_offset = 0;
1924
1925         set_page_extent_mapped(page);
1926
1927         delalloc_start = start;
1928         delalloc_end = 0;
1929         while(delalloc_end < page_end) {
1930                 nr_delalloc = find_lock_delalloc_range(tree, &delalloc_start,
1931                                                        &delalloc_end,
1932                                                        128 * 1024 * 1024);
1933                 if (nr_delalloc == 0) {
1934                         delalloc_start = delalloc_end + 1;
1935                         continue;
1936                 }
1937                 tree->ops->fill_delalloc(inode, delalloc_start,
1938                                          delalloc_end);
1939                 clear_extent_bit(tree, delalloc_start,
1940                                  delalloc_end,
1941                                  EXTENT_LOCKED | EXTENT_DELALLOC,
1942                                  1, 0, GFP_NOFS);
1943                 delalloc_start = delalloc_end + 1;
1944         }
1945         lock_extent(tree, start, page_end, GFP_NOFS);
1946         unlock_start = start;
1947
1948         if (tree->ops && tree->ops->writepage_start_hook) {
1949                 ret = tree->ops->writepage_start_hook(page, start, page_end);
1950                 if (ret == -EAGAIN) {
1951                         unlock_extent(tree, start, page_end, GFP_NOFS);
1952                         redirty_page_for_writepage(wbc, page);
1953                         unlock_page(page);
1954                         return 0;
1955                 }
1956         }
1957
1958         end = page_end;
1959         if (test_range_bit(tree, start, page_end, EXTENT_DELALLOC, 0)) {
1960                 printk("found delalloc bits after lock_extent\n");
1961         }
1962
1963         if (last_byte <= start) {
1964                 clear_extent_dirty(tree, start, page_end, GFP_NOFS);
1965                 unlock_extent(tree, start, page_end, GFP_NOFS);
1966                 if (tree->ops && tree->ops->writepage_end_io_hook)
1967                         tree->ops->writepage_end_io_hook(page, start,
1968                                                          page_end, NULL, 1);
1969                 unlock_start = page_end + 1;
1970                 goto done;
1971         }
1972
1973         set_extent_uptodate(tree, start, page_end, GFP_NOFS);
1974         blocksize = inode->i_sb->s_blocksize;
1975
1976         while (cur <= end) {
1977                 if (cur >= last_byte) {
1978                         clear_extent_dirty(tree, cur, page_end, GFP_NOFS);
1979                         unlock_extent(tree, unlock_start, page_end, GFP_NOFS);
1980                         if (tree->ops && tree->ops->writepage_end_io_hook)
1981                                 tree->ops->writepage_end_io_hook(page, cur,
1982                                                          page_end, NULL, 1);
1983                         unlock_start = page_end + 1;
1984                         break;
1985                 }
1986                 em = epd->get_extent(inode, page, pg_offset, cur,
1987                                      end - cur + 1, 1);
1988                 if (IS_ERR(em) || !em) {
1989                         SetPageError(page);
1990                         break;
1991                 }
1992
1993                 extent_offset = cur - em->start;
1994                 BUG_ON(extent_map_end(em) <= cur);
1995                 BUG_ON(end < cur);
1996                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
1997                 iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
1998                 sector = (em->block_start + extent_offset) >> 9;
1999                 bdev = em->bdev;
2000                 block_start = em->block_start;
2001                 free_extent_map(em);
2002                 em = NULL;
2003
2004                 if (block_start == EXTENT_MAP_HOLE ||
2005                     block_start == EXTENT_MAP_INLINE) {
2006                         clear_extent_dirty(tree, cur,
2007                                            cur + iosize - 1, GFP_NOFS);
2008
2009                         unlock_extent(tree, unlock_start, cur + iosize -1,
2010                                       GFP_NOFS);
2011
2012                         if (tree->ops && tree->ops->writepage_end_io_hook)
2013                                 tree->ops->writepage_end_io_hook(page, cur,
2014                                                          cur + iosize - 1,
2015                                                          NULL, 1);
2016                         cur = cur + iosize;
2017                         pg_offset += iosize;
2018                         unlock_start = cur;
2019                         continue;
2020                 }
2021
2022                 /* leave this out until we have a page_mkwrite call */
2023                 if (0 && !test_range_bit(tree, cur, cur + iosize - 1,
2024                                    EXTENT_DIRTY, 0)) {
2025                         cur = cur + iosize;
2026                         pg_offset += iosize;
2027                         continue;
2028                 }
2029                 clear_extent_dirty(tree, cur, cur + iosize - 1, GFP_NOFS);
2030                 if (tree->ops && tree->ops->writepage_io_hook) {
2031                         ret = tree->ops->writepage_io_hook(page, cur,
2032                                                 cur + iosize - 1);
2033                 } else {
2034                         ret = 0;
2035                 }
2036                 if (ret) {
2037                         SetPageError(page);
2038                 } else {
2039                         unsigned long max_nr = end_index + 1;
2040
2041                         set_range_writeback(tree, cur, cur + iosize - 1);
2042                         if (!PageWriteback(page)) {
2043                                 printk("warning page %lu not writeback, "
2044                                        "cur %llu end %llu\n", page->index,
2045                                        (unsigned long long)cur,
2046                                        (unsigned long long)end);
2047                         }
2048
2049                         ret = submit_extent_page(WRITE, tree, page, sector,
2050                                                  iosize, pg_offset, bdev,
2051                                                  &epd->bio, max_nr,
2052                                                  end_bio_extent_writepage, 0);
2053                         if (ret)
2054                                 SetPageError(page);
2055                 }
2056                 cur = cur + iosize;
2057                 pg_offset += iosize;
2058                 nr++;
2059         }
2060 done:
2061         if (nr == 0) {
2062                 /* make sure the mapping tag for page dirty gets cleared */
2063                 set_page_writeback(page);
2064                 end_page_writeback(page);
2065         }
2066         if (unlock_start <= page_end)
2067                 unlock_extent(tree, unlock_start, page_end, GFP_NOFS);
2068         unlock_page(page);
2069         return 0;
2070 }
2071
2072 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
2073 /* Taken directly from 2.6.23 for 2.6.18 back port */
2074 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
2075                                 void *data);
2076
2077 /**
2078  * write_cache_pages - walk the list of dirty pages of the given address space
2079  * and write all of them.
2080  * @mapping: address space structure to write
2081  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
2082  * @writepage: function called for each page
2083  * @data: data passed to writepage function
2084  *
2085  * If a page is already under I/O, write_cache_pages() skips it, even
2086  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
2087  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
2088  * and msync() need to guarantee that all the data which was dirty at the time
2089  * the call was made get new I/O started against them.  If wbc->sync_mode is
2090  * WB_SYNC_ALL then we were called for data integrity and we must wait for
2091  * existing IO to complete.
2092  */
2093 static int write_cache_pages(struct address_space *mapping,
2094                       struct writeback_control *wbc, writepage_t writepage,
2095                       void *data)
2096 {
2097         struct backing_dev_info *bdi = mapping->backing_dev_info;
2098         int ret = 0;
2099         int done = 0;
2100         struct pagevec pvec;
2101         int nr_pages;
2102         pgoff_t index;
2103         pgoff_t end;            /* Inclusive */
2104         int scanned = 0;
2105         int range_whole = 0;
2106
2107         if (wbc->nonblocking && bdi_write_congested(bdi)) {
2108                 wbc->encountered_congestion = 1;
2109                 return 0;
2110         }
2111
2112         pagevec_init(&pvec, 0);
2113         if (wbc->range_cyclic) {
2114                 index = mapping->writeback_index; /* Start from prev offset */
2115                 end = -1;
2116         } else {
2117                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2118                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
2119                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2120                         range_whole = 1;
2121                 scanned = 1;
2122         }
2123 retry:
2124         while (!done && (index <= end) &&
2125                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
2126                                               PAGECACHE_TAG_DIRTY,
2127                                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
2128                 unsigned i;
2129
2130                 scanned = 1;
2131                 for (i = 0; i < nr_pages; i++) {
2132                         struct page *page = pvec.pages[i];
2133
2134                         /*
2135                          * At this point we hold neither mapping->tree_lock nor
2136                          * lock on the page itself: the page may be truncated or
2137                          * invalidated (changing page->mapping to NULL), or even
2138                          * swizzled back from swapper_space to tmpfs file
2139                          * mapping
2140                          */
2141                         lock_page(page);
2142
2143                         if (unlikely(page->mapping != mapping)) {
2144                                 unlock_page(page);
2145                                 continue;
2146                         }
2147
2148                         if (!wbc->range_cyclic && page->index > end) {
2149                                 done = 1;
2150                                 unlock_page(page);
2151                                 continue;
2152                         }
2153
2154                         if (wbc->sync_mode != WB_SYNC_NONE)
2155                                 wait_on_page_writeback(page);
2156
2157                         if (PageWriteback(page) ||
2158                             !clear_page_dirty_for_io(page)) {
2159                                 unlock_page(page);
2160                                 continue;
2161                         }
2162
2163                         ret = (*writepage)(page, wbc, data);
2164
2165                         if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
2166                                 unlock_page(page);
2167                                 ret = 0;
2168                         }
2169                         if (ret || (--(wbc->nr_to_write) <= 0))
2170                                 done = 1;
2171                         if (wbc->nonblocking && bdi_write_congested(bdi)) {
2172                                 wbc->encountered_congestion = 1;
2173                                 done = 1;
2174                         }
2175                 }
2176                 pagevec_release(&pvec);
2177                 cond_resched();
2178         }
2179         if (!scanned && !done) {
2180                 /*
2181                  * We hit the last page and there is more work to be done: wrap
2182                  * back to the start of the file
2183                  */
2184                 scanned = 1;
2185                 index = 0;
2186                 goto retry;
2187         }
2188         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2189                 mapping->writeback_index = index;
2190         return ret;
2191 }
2192 #endif
2193
2194 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
2195                           get_extent_t *get_extent,
2196                           struct writeback_control *wbc)
2197 {
2198         int ret;
2199         struct address_space *mapping = page->mapping;
2200         struct extent_page_data epd = {
2201                 .bio = NULL,
2202                 .tree = tree,
2203                 .get_extent = get_extent,
2204         };
2205         struct writeback_control wbc_writepages = {
2206                 .bdi            = wbc->bdi,
2207                 .sync_mode      = WB_SYNC_NONE,
2208                 .older_than_this = NULL,
2209                 .nr_to_write    = 64,
2210                 .range_start    = page_offset(page) + PAGE_CACHE_SIZE,
2211                 .range_end      = (loff_t)-1,
2212         };
2213
2214
2215         ret = __extent_writepage(page, wbc, &epd);
2216
2217         write_cache_pages(mapping, &wbc_writepages, __extent_writepage, &epd);
2218         if (epd.bio) {
2219                 submit_one_bio(WRITE, epd.bio, 0);
2220         }
2221         return ret;
2222 }
2223 EXPORT_SYMBOL(extent_write_full_page);
2224
2225
2226 int extent_writepages(struct extent_io_tree *tree,
2227                       struct address_space *mapping,
2228                       get_extent_t *get_extent,
2229                       struct writeback_control *wbc)
2230 {
2231         int ret = 0;
2232         struct extent_page_data epd = {
2233                 .bio = NULL,
2234                 .tree = tree,
2235                 .get_extent = get_extent,
2236         };
2237
2238         ret = write_cache_pages(mapping, wbc, __extent_writepage, &epd);
2239         if (epd.bio) {
2240                 submit_one_bio(WRITE, epd.bio, 0);
2241         }
2242         return ret;
2243 }
2244 EXPORT_SYMBOL(extent_writepages);
2245
2246 int extent_readpages(struct extent_io_tree *tree,
2247                      struct address_space *mapping,
2248                      struct list_head *pages, unsigned nr_pages,
2249                      get_extent_t get_extent)
2250 {
2251         struct bio *bio = NULL;
2252         unsigned page_idx;
2253         struct pagevec pvec;
2254
2255         pagevec_init(&pvec, 0);
2256         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
2257                 struct page *page = list_entry(pages->prev, struct page, lru);
2258
2259                 prefetchw(&page->flags);
2260                 list_del(&page->lru);
2261                 /*
2262                  * what we want to do here is call add_to_page_cache_lru,
2263                  * but that isn't exported, so we reproduce it here
2264                  */
2265                 if (!add_to_page_cache(page, mapping,
2266                                         page->index, GFP_KERNEL)) {
2267
2268                         /* open coding of lru_cache_add, also not exported */
2269                         page_cache_get(page);
2270                         if (!pagevec_add(&pvec, page))
2271                                 __pagevec_lru_add(&pvec);
2272                         __extent_read_full_page(tree, page, get_extent,
2273                                                 &bio, 0);
2274                 }
2275                 page_cache_release(page);
2276         }
2277         if (pagevec_count(&pvec))
2278                 __pagevec_lru_add(&pvec);
2279         BUG_ON(!list_empty(pages));
2280         if (bio)
2281                 submit_one_bio(READ, bio, 0);
2282         return 0;
2283 }
2284 EXPORT_SYMBOL(extent_readpages);
2285
2286 /*
2287  * basic invalidatepage code, this waits on any locked or writeback
2288  * ranges corresponding to the page, and then deletes any extent state
2289  * records from the tree
2290  */
2291 int extent_invalidatepage(struct extent_io_tree *tree,
2292                           struct page *page, unsigned long offset)
2293 {
2294         u64 start = ((u64)page->index << PAGE_CACHE_SHIFT);
2295         u64 end = start + PAGE_CACHE_SIZE - 1;
2296         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
2297
2298         start += (offset + blocksize -1) & ~(blocksize - 1);
2299         if (start > end)
2300                 return 0;
2301
2302         lock_extent(tree, start, end, GFP_NOFS);
2303         wait_on_extent_writeback(tree, start, end);
2304         clear_extent_bit(tree, start, end,
2305                          EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC,
2306                          1, 1, GFP_NOFS);
2307         return 0;
2308 }
2309 EXPORT_SYMBOL(extent_invalidatepage);
2310
2311 /*
2312  * simple commit_write call, set_range_dirty is used to mark both
2313  * the pages and the extent records as dirty
2314  */
2315 int extent_commit_write(struct extent_io_tree *tree,
2316                         struct inode *inode, struct page *page,
2317                         unsigned from, unsigned to)
2318 {
2319         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
2320
2321         set_page_extent_mapped(page);
2322         set_page_dirty(page);
2323
2324         if (pos > inode->i_size) {
2325                 i_size_write(inode, pos);
2326                 mark_inode_dirty(inode);
2327         }
2328         return 0;
2329 }
2330 EXPORT_SYMBOL(extent_commit_write);
2331
2332 int extent_prepare_write(struct extent_io_tree *tree,
2333                          struct inode *inode, struct page *page,
2334                          unsigned from, unsigned to, get_extent_t *get_extent)
2335 {
2336         u64 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2337         u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
2338         u64 block_start;
2339         u64 orig_block_start;
2340         u64 block_end;
2341         u64 cur_end;
2342         struct extent_map *em;
2343         unsigned blocksize = 1 << inode->i_blkbits;
2344         size_t page_offset = 0;
2345         size_t block_off_start;
2346         size_t block_off_end;
2347         int err = 0;
2348         int iocount = 0;
2349         int ret = 0;
2350         int isnew;
2351
2352         set_page_extent_mapped(page);
2353
2354         block_start = (page_start + from) & ~((u64)blocksize - 1);
2355         block_end = (page_start + to - 1) | (blocksize - 1);
2356         orig_block_start = block_start;
2357
2358         lock_extent(tree, page_start, page_end, GFP_NOFS);
2359         while(block_start <= block_end) {
2360                 em = get_extent(inode, page, page_offset, block_start,
2361                                 block_end - block_start + 1, 1);
2362                 if (IS_ERR(em) || !em) {
2363                         goto err;
2364                 }
2365                 cur_end = min(block_end, extent_map_end(em) - 1);
2366                 block_off_start = block_start & (PAGE_CACHE_SIZE - 1);
2367                 block_off_end = block_off_start + blocksize;
2368                 isnew = clear_extent_new(tree, block_start, cur_end, GFP_NOFS);
2369
2370                 if (!PageUptodate(page) && isnew &&
2371                     (block_off_end > to || block_off_start < from)) {
2372                         void *kaddr;
2373
2374                         kaddr = kmap_atomic(page, KM_USER0);
2375                         if (block_off_end > to)
2376                                 memset(kaddr + to, 0, block_off_end - to);
2377                         if (block_off_start < from)
2378                                 memset(kaddr + block_off_start, 0,
2379                                        from - block_off_start);
2380                         flush_dcache_page(page);
2381                         kunmap_atomic(kaddr, KM_USER0);
2382                 }
2383                 if ((em->block_start != EXTENT_MAP_HOLE &&
2384                      em->block_start != EXTENT_MAP_INLINE) &&
2385                     !isnew && !PageUptodate(page) &&
2386                     (block_off_end > to || block_off_start < from) &&
2387                     !test_range_bit(tree, block_start, cur_end,
2388                                     EXTENT_UPTODATE, 1)) {
2389                         u64 sector;
2390                         u64 extent_offset = block_start - em->start;
2391                         size_t iosize;
2392                         sector = (em->block_start + extent_offset) >> 9;
2393                         iosize = (cur_end - block_start + blocksize) &
2394                                 ~((u64)blocksize - 1);
2395                         /*
2396                          * we've already got the extent locked, but we
2397                          * need to split the state such that our end_bio
2398                          * handler can clear the lock.
2399                          */
2400                         set_extent_bit(tree, block_start,
2401                                        block_start + iosize - 1,
2402                                        EXTENT_LOCKED, 0, NULL, GFP_NOFS);
2403                         ret = submit_extent_page(READ, tree, page,
2404                                          sector, iosize, page_offset, em->bdev,
2405                                          NULL, 1,
2406                                          end_bio_extent_preparewrite, 0);
2407                         iocount++;
2408                         block_start = block_start + iosize;
2409                 } else {
2410                         set_extent_uptodate(tree, block_start, cur_end,
2411                                             GFP_NOFS);
2412                         unlock_extent(tree, block_start, cur_end, GFP_NOFS);
2413                         block_start = cur_end + 1;
2414                 }
2415                 page_offset = block_start & (PAGE_CACHE_SIZE - 1);
2416                 free_extent_map(em);
2417         }
2418         if (iocount) {
2419                 wait_extent_bit(tree, orig_block_start,
2420                                 block_end, EXTENT_LOCKED);
2421         }
2422         check_page_uptodate(tree, page);
2423 err:
2424         /* FIXME, zero out newly allocated blocks on error */
2425         return err;
2426 }
2427 EXPORT_SYMBOL(extent_prepare_write);
2428
2429 /*
2430  * a helper for releasepage, this tests for areas of the page that
2431  * are locked or under IO and drops the related state bits if it is safe
2432  * to drop the page.
2433  */
2434 int try_release_extent_state(struct extent_map_tree *map,
2435                              struct extent_io_tree *tree, struct page *page,
2436                              gfp_t mask)
2437 {
2438         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2439         u64 end = start + PAGE_CACHE_SIZE - 1;
2440         int ret = 1;
2441
2442         if (test_range_bit(tree, start, end,
2443                            EXTENT_IOBITS | EXTENT_ORDERED, 0))
2444                 ret = 0;
2445         else {
2446                 if ((mask & GFP_NOFS) == GFP_NOFS)
2447                         mask = GFP_NOFS;
2448                 clear_extent_bit(tree, start, end, EXTENT_UPTODATE,
2449                                  1, 1, mask);
2450         }
2451         return ret;
2452 }
2453 EXPORT_SYMBOL(try_release_extent_state);
2454
2455 /*
2456  * a helper for releasepage.  As long as there are no locked extents
2457  * in the range corresponding to the page, both state records and extent
2458  * map records are removed
2459  */
2460 int try_release_extent_mapping(struct extent_map_tree *map,
2461                                struct extent_io_tree *tree, struct page *page,
2462                                gfp_t mask)
2463 {
2464         struct extent_map *em;
2465         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2466         u64 end = start + PAGE_CACHE_SIZE - 1;
2467
2468         if ((mask & __GFP_WAIT) &&
2469             page->mapping->host->i_size > 16 * 1024 * 1024) {
2470                 u64 len;
2471                 while (start <= end) {
2472                         len = end - start + 1;
2473                         spin_lock(&map->lock);
2474                         em = lookup_extent_mapping(map, start, len);
2475                         if (!em || IS_ERR(em)) {
2476                                 spin_unlock(&map->lock);
2477                                 break;
2478                         }
2479                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
2480                             em->start != start) {
2481                                 spin_unlock(&map->lock);
2482                                 free_extent_map(em);
2483                                 break;
2484                         }
2485                         if (!test_range_bit(tree, em->start,
2486                                             extent_map_end(em) - 1,
2487                                             EXTENT_LOCKED, 0)) {
2488                                 remove_extent_mapping(map, em);
2489                                 /* once for the rb tree */
2490                                 free_extent_map(em);
2491                         }
2492                         start = extent_map_end(em);
2493                         spin_unlock(&map->lock);
2494
2495                         /* once for us */
2496                         free_extent_map(em);
2497                 }
2498         }
2499         return try_release_extent_state(map, tree, page, mask);
2500 }
2501 EXPORT_SYMBOL(try_release_extent_mapping);
2502
2503 sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
2504                 get_extent_t *get_extent)
2505 {
2506         struct inode *inode = mapping->host;
2507         u64 start = iblock << inode->i_blkbits;
2508         sector_t sector = 0;
2509         struct extent_map *em;
2510
2511         em = get_extent(inode, NULL, 0, start, (1 << inode->i_blkbits), 0);
2512         if (!em || IS_ERR(em))
2513                 return 0;
2514
2515         if (em->block_start == EXTENT_MAP_INLINE ||
2516             em->block_start == EXTENT_MAP_HOLE)
2517                 goto out;
2518
2519         sector = (em->block_start + start - em->start) >> inode->i_blkbits;
2520 out:
2521         free_extent_map(em);
2522         return sector;
2523 }
2524
2525 static inline struct page *extent_buffer_page(struct extent_buffer *eb,
2526                                               unsigned long i)
2527 {
2528         struct page *p;
2529         struct address_space *mapping;
2530
2531         if (i == 0)
2532                 return eb->first_page;
2533         i += eb->start >> PAGE_CACHE_SHIFT;
2534         mapping = eb->first_page->mapping;
2535         if (!mapping)
2536                 return NULL;
2537
2538         /*
2539          * extent_buffer_page is only called after pinning the page
2540          * by increasing the reference count.  So we know the page must
2541          * be in the radix tree.
2542          */
2543 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,26)
2544         rcu_read_lock();
2545 #else
2546         read_lock_irq(&mapping->tree_lock);
2547 #endif
2548         p = radix_tree_lookup(&mapping->page_tree, i);
2549
2550 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,26)
2551         rcu_read_unlock();
2552 #else
2553         read_unlock_irq(&mapping->tree_lock);
2554 #endif
2555         return p;
2556 }
2557
2558 static inline unsigned long num_extent_pages(u64 start, u64 len)
2559 {
2560         return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
2561                 (start >> PAGE_CACHE_SHIFT);
2562 }
2563
2564 static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
2565                                                    u64 start,
2566                                                    unsigned long len,
2567                                                    gfp_t mask)
2568 {
2569         struct extent_buffer *eb = NULL;
2570         unsigned long flags;
2571
2572         eb = kmem_cache_zalloc(extent_buffer_cache, mask);
2573         eb->start = start;
2574         eb->len = len;
2575         mutex_init(&eb->mutex);
2576         spin_lock_irqsave(&leak_lock, flags);
2577         list_add(&eb->leak_list, &buffers);
2578         spin_unlock_irqrestore(&leak_lock, flags);
2579         atomic_set(&eb->refs, 1);
2580
2581         return eb;
2582 }
2583
2584 static void __free_extent_buffer(struct extent_buffer *eb)
2585 {
2586         unsigned long flags;
2587         spin_lock_irqsave(&leak_lock, flags);
2588         list_del(&eb->leak_list);
2589         spin_unlock_irqrestore(&leak_lock, flags);
2590         kmem_cache_free(extent_buffer_cache, eb);
2591 }
2592
2593 struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
2594                                           u64 start, unsigned long len,
2595                                           struct page *page0,
2596                                           gfp_t mask)
2597 {
2598         unsigned long num_pages = num_extent_pages(start, len);
2599         unsigned long i;
2600         unsigned long index = start >> PAGE_CACHE_SHIFT;
2601         struct extent_buffer *eb;
2602         struct extent_buffer *exists = NULL;
2603         struct page *p;
2604         struct address_space *mapping = tree->mapping;
2605         int uptodate = 1;
2606
2607         spin_lock(&tree->buffer_lock);
2608         eb = buffer_search(tree, start);
2609         if (eb) {
2610                 atomic_inc(&eb->refs);
2611                 spin_unlock(&tree->buffer_lock);
2612                 return eb;
2613         }
2614         spin_unlock(&tree->buffer_lock);
2615
2616         eb = __alloc_extent_buffer(tree, start, len, mask);
2617         if (!eb)
2618                 return NULL;
2619
2620         if (page0) {
2621                 eb->first_page = page0;
2622                 i = 1;
2623                 index++;
2624                 page_cache_get(page0);
2625                 mark_page_accessed(page0);
2626                 set_page_extent_mapped(page0);
2627                 set_page_extent_head(page0, len);
2628                 uptodate = PageUptodate(page0);
2629         } else {
2630                 i = 0;
2631         }
2632         for (; i < num_pages; i++, index++) {
2633                 p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
2634                 if (!p) {
2635                         WARN_ON(1);
2636                         goto free_eb;
2637                 }
2638                 set_page_extent_mapped(p);
2639                 mark_page_accessed(p);
2640                 if (i == 0) {
2641                         eb->first_page = p;
2642                         set_page_extent_head(p, len);
2643                 } else {
2644                         set_page_private(p, EXTENT_PAGE_PRIVATE);
2645                 }
2646                 if (!PageUptodate(p))
2647                         uptodate = 0;
2648                 unlock_page(p);
2649         }
2650         if (uptodate)
2651                 eb->flags |= EXTENT_UPTODATE;
2652         eb->flags |= EXTENT_BUFFER_FILLED;
2653
2654         spin_lock(&tree->buffer_lock);
2655         exists = buffer_tree_insert(tree, start, &eb->rb_node);
2656         if (exists) {
2657                 /* add one reference for the caller */
2658                 atomic_inc(&exists->refs);
2659                 spin_unlock(&tree->buffer_lock);
2660                 goto free_eb;
2661         }
2662         spin_unlock(&tree->buffer_lock);
2663
2664         /* add one reference for the tree */
2665         atomic_inc(&eb->refs);
2666         return eb;
2667
2668 free_eb:
2669         if (!atomic_dec_and_test(&eb->refs))
2670                 return exists;
2671         for (index = 1; index < i; index++)
2672                 page_cache_release(extent_buffer_page(eb, index));
2673         page_cache_release(extent_buffer_page(eb, 0));
2674         __free_extent_buffer(eb);
2675         return exists;
2676 }
2677 EXPORT_SYMBOL(alloc_extent_buffer);
2678
2679 struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
2680                                          u64 start, unsigned long len,
2681                                           gfp_t mask)
2682 {
2683         struct extent_buffer *eb;
2684
2685         spin_lock(&tree->buffer_lock);
2686         eb = buffer_search(tree, start);
2687         if (eb)
2688                 atomic_inc(&eb->refs);
2689         spin_unlock(&tree->buffer_lock);
2690
2691         return eb;
2692 }
2693 EXPORT_SYMBOL(find_extent_buffer);
2694
2695 void free_extent_buffer(struct extent_buffer *eb)
2696 {
2697         if (!eb)
2698                 return;
2699
2700         if (!atomic_dec_and_test(&eb->refs))
2701                 return;
2702
2703         WARN_ON(1);
2704 }
2705 EXPORT_SYMBOL(free_extent_buffer);
2706
2707 int clear_extent_buffer_dirty(struct extent_io_tree *tree,
2708                               struct extent_buffer *eb)
2709 {
2710         int set;
2711         unsigned long i;
2712         unsigned long num_pages;
2713         struct page *page;
2714
2715         u64 start = eb->start;
2716         u64 end = start + eb->len - 1;
2717
2718         set = clear_extent_dirty(tree, start, end, GFP_NOFS);
2719         num_pages = num_extent_pages(eb->start, eb->len);
2720
2721         for (i = 0; i < num_pages; i++) {
2722                 page = extent_buffer_page(eb, i);
2723                 lock_page(page);
2724                 if (i == 0)
2725                         set_page_extent_head(page, eb->len);
2726                 else
2727                         set_page_private(page, EXTENT_PAGE_PRIVATE);
2728
2729                 /*
2730                  * if we're on the last page or the first page and the
2731                  * block isn't aligned on a page boundary, do extra checks
2732                  * to make sure we don't clean page that is partially dirty
2733                  */
2734                 if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
2735                     ((i == num_pages - 1) &&
2736                      ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
2737                         start = (u64)page->index << PAGE_CACHE_SHIFT;
2738                         end  = start + PAGE_CACHE_SIZE - 1;
2739                         if (test_range_bit(tree, start, end,
2740                                            EXTENT_DIRTY, 0)) {
2741                                 unlock_page(page);
2742                                 continue;
2743                         }
2744                 }
2745                 clear_page_dirty_for_io(page);
2746 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,26)
2747                 spin_lock_irq(&page->mapping->tree_lock);
2748 #else
2749                 read_lock_irq(&page->mapping->tree_lock);
2750 #endif
2751                 if (!PageDirty(page)) {
2752                         radix_tree_tag_clear(&page->mapping->page_tree,
2753                                                 page_index(page),
2754                                                 PAGECACHE_TAG_DIRTY);
2755                 }
2756 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,26)
2757                 spin_unlock_irq(&page->mapping->tree_lock);
2758 #else
2759                 read_unlock_irq(&page->mapping->tree_lock);
2760 #endif
2761                 unlock_page(page);
2762         }
2763         return 0;
2764 }
2765 EXPORT_SYMBOL(clear_extent_buffer_dirty);
2766
2767 int wait_on_extent_buffer_writeback(struct extent_io_tree *tree,
2768                                     struct extent_buffer *eb)
2769 {
2770         return wait_on_extent_writeback(tree, eb->start,
2771                                         eb->start + eb->len - 1);
2772 }
2773 EXPORT_SYMBOL(wait_on_extent_buffer_writeback);
2774
2775 int set_extent_buffer_dirty(struct extent_io_tree *tree,
2776                              struct extent_buffer *eb)
2777 {
2778         unsigned long i;
2779         unsigned long num_pages;
2780
2781         num_pages = num_extent_pages(eb->start, eb->len);
2782         for (i = 0; i < num_pages; i++) {
2783                 struct page *page = extent_buffer_page(eb, i);
2784                 /* writepage may need to do something special for the
2785                  * first page, we have to make sure page->private is
2786                  * properly set.  releasepage may drop page->private
2787                  * on us if the page isn't already dirty.
2788                  */
2789                 lock_page(page);
2790                 if (i == 0) {
2791                         set_page_extent_head(page, eb->len);
2792                 } else if (PagePrivate(page) &&
2793                            page->private != EXTENT_PAGE_PRIVATE) {
2794                         set_page_extent_mapped(page);
2795                 }
2796                 __set_page_dirty_nobuffers(extent_buffer_page(eb, i));
2797                 set_extent_dirty(tree, page_offset(page),
2798                                  page_offset(page) + PAGE_CACHE_SIZE -1,
2799                                  GFP_NOFS);
2800                 unlock_page(page);
2801         }
2802         return 0;
2803 }
2804 EXPORT_SYMBOL(set_extent_buffer_dirty);
2805
2806 int clear_extent_buffer_uptodate(struct extent_io_tree *tree,
2807                                 struct extent_buffer *eb)
2808 {
2809         unsigned long i;
2810         struct page *page;
2811         unsigned long num_pages;
2812
2813         num_pages = num_extent_pages(eb->start, eb->len);
2814         eb->flags &= ~EXTENT_UPTODATE;
2815
2816         clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
2817                               GFP_NOFS);
2818         for (i = 0; i < num_pages; i++) {
2819                 page = extent_buffer_page(eb, i);
2820                 if (page)
2821                         ClearPageUptodate(page);
2822         }
2823         return 0;
2824 }
2825
2826 int set_extent_buffer_uptodate(struct extent_io_tree *tree,
2827                                 struct extent_buffer *eb)
2828 {
2829         unsigned long i;
2830         struct page *page;
2831         unsigned long num_pages;
2832
2833         num_pages = num_extent_pages(eb->start, eb->len);
2834
2835         set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
2836                             GFP_NOFS);
2837         for (i = 0; i < num_pages; i++) {
2838                 page = extent_buffer_page(eb, i);
2839                 if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
2840                     ((i == num_pages - 1) &&
2841                      ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
2842                         check_page_uptodate(tree, page);
2843                         continue;
2844                 }
2845                 SetPageUptodate(page);
2846         }
2847         return 0;
2848 }
2849 EXPORT_SYMBOL(set_extent_buffer_uptodate);
2850
2851 int extent_range_uptodate(struct extent_io_tree *tree,
2852                           u64 start, u64 end)
2853 {
2854         struct page *page;
2855         int ret;
2856         int pg_uptodate = 1;
2857         int uptodate;
2858         unsigned long index;
2859
2860         ret = test_range_bit(tree, start, end, EXTENT_UPTODATE, 1);
2861         if (ret)
2862                 return 1;
2863         while(start <= end) {
2864                 index = start >> PAGE_CACHE_SHIFT;
2865                 page = find_get_page(tree->mapping, index);
2866                 uptodate = PageUptodate(page);
2867                 page_cache_release(page);
2868                 if (!uptodate) {
2869                         pg_uptodate = 0;
2870                         break;
2871                 }
2872                 start += PAGE_CACHE_SIZE;
2873         }
2874         return pg_uptodate;
2875 }
2876
2877 int extent_buffer_uptodate(struct extent_io_tree *tree,
2878                            struct extent_buffer *eb)
2879 {
2880         int ret = 0;
2881         unsigned long num_pages;
2882         unsigned long i;
2883         struct page *page;
2884         int pg_uptodate = 1;
2885
2886         if (eb->flags & EXTENT_UPTODATE)
2887                 return 1;
2888
2889         ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1,
2890                            EXTENT_UPTODATE, 1);
2891         if (ret)
2892                 return ret;
2893
2894         num_pages = num_extent_pages(eb->start, eb->len);
2895         for (i = 0; i < num_pages; i++) {
2896                 page = extent_buffer_page(eb, i);
2897                 if (!PageUptodate(page)) {
2898                         pg_uptodate = 0;
2899                         break;
2900                 }
2901         }
2902         return pg_uptodate;
2903 }
2904 EXPORT_SYMBOL(extent_buffer_uptodate);
2905
2906 int read_extent_buffer_pages(struct extent_io_tree *tree,
2907                              struct extent_buffer *eb,
2908                              u64 start, int wait,
2909                              get_extent_t *get_extent, int mirror_num)
2910 {
2911         unsigned long i;
2912         unsigned long start_i;
2913         struct page *page;
2914         int err;
2915         int ret = 0;
2916         int locked_pages = 0;
2917         int all_uptodate = 1;
2918         int inc_all_pages = 0;
2919         unsigned long num_pages;
2920         struct bio *bio = NULL;
2921
2922         if (eb->flags & EXTENT_UPTODATE)
2923                 return 0;
2924
2925         if (test_range_bit(tree, eb->start, eb->start + eb->len - 1,
2926                            EXTENT_UPTODATE, 1)) {
2927                 return 0;
2928         }
2929
2930         if (start) {
2931                 WARN_ON(start < eb->start);
2932                 start_i = (start >> PAGE_CACHE_SHIFT) -
2933                         (eb->start >> PAGE_CACHE_SHIFT);
2934         } else {
2935                 start_i = 0;
2936         }
2937
2938         num_pages = num_extent_pages(eb->start, eb->len);
2939         for (i = start_i; i < num_pages; i++) {
2940                 page = extent_buffer_page(eb, i);
2941                 if (!wait) {
2942                         if (!trylock_page(page))
2943                                 goto unlock_exit;
2944                 } else {
2945                         lock_page(page);
2946                 }
2947                 locked_pages++;
2948                 if (!PageUptodate(page)) {
2949                         all_uptodate = 0;
2950                 }
2951         }
2952         if (all_uptodate) {
2953                 if (start_i == 0)
2954                         eb->flags |= EXTENT_UPTODATE;
2955                 if (ret) {
2956                         printk("all up to date but ret is %d\n", ret);
2957                 }
2958                 goto unlock_exit;
2959         }
2960
2961         for (i = start_i; i < num_pages; i++) {
2962                 page = extent_buffer_page(eb, i);
2963                 if (inc_all_pages)
2964                         page_cache_get(page);
2965                 if (!PageUptodate(page)) {
2966                         if (start_i == 0)
2967                                 inc_all_pages = 1;
2968                         ClearPageError(page);
2969                         err = __extent_read_full_page(tree, page,
2970                                                       get_extent, &bio,
2971                                                       mirror_num);
2972                         if (err) {
2973                                 ret = err;
2974                                 printk("err %d from __extent_read_full_page\n", ret);
2975                         }
2976                 } else {
2977                         unlock_page(page);
2978                 }
2979         }
2980
2981         if (bio)
2982                 submit_one_bio(READ, bio, mirror_num);
2983
2984         if (ret || !wait) {
2985                 if (ret)
2986                         printk("ret %d wait %d returning\n", ret, wait);
2987                 return ret;
2988         }
2989         for (i = start_i; i < num_pages; i++) {
2990                 page = extent_buffer_page(eb, i);
2991                 wait_on_page_locked(page);
2992                 if (!PageUptodate(page)) {
2993                         printk("page not uptodate after wait_on_page_locked\n");
2994                         ret = -EIO;
2995                 }
2996         }
2997         if (!ret)
2998                 eb->flags |= EXTENT_UPTODATE;
2999         return ret;
3000
3001 unlock_exit:
3002         i = start_i;
3003         while(locked_pages > 0) {
3004                 page = extent_buffer_page(eb, i);
3005                 i++;
3006                 unlock_page(page);
3007                 locked_pages--;
3008         }
3009         return ret;
3010 }
3011 EXPORT_SYMBOL(read_extent_buffer_pages);
3012
3013 void read_extent_buffer(struct extent_buffer *eb, void *dstv,
3014                         unsigned long start,
3015                         unsigned long len)
3016 {
3017         size_t cur;
3018         size_t offset;
3019         struct page *page;
3020         char *kaddr;
3021         char *dst = (char *)dstv;
3022         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3023         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3024
3025         WARN_ON(start > eb->len);
3026         WARN_ON(start + len > eb->start + eb->len);
3027
3028         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3029
3030         while(len > 0) {
3031                 page = extent_buffer_page(eb, i);
3032
3033                 cur = min(len, (PAGE_CACHE_SIZE - offset));
3034                 kaddr = kmap_atomic(page, KM_USER1);
3035                 memcpy(dst, kaddr + offset, cur);
3036                 kunmap_atomic(kaddr, KM_USER1);
3037
3038                 dst += cur;
3039                 len -= cur;
3040                 offset = 0;
3041                 i++;
3042         }
3043 }
3044 EXPORT_SYMBOL(read_extent_buffer);
3045
3046 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
3047                                unsigned long min_len, char **token, char **map,
3048                                unsigned long *map_start,
3049                                unsigned long *map_len, int km)
3050 {
3051         size_t offset = start & (PAGE_CACHE_SIZE - 1);
3052         char *kaddr;
3053         struct page *p;
3054         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3055         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3056         unsigned long end_i = (start_offset + start + min_len - 1) >>
3057                 PAGE_CACHE_SHIFT;
3058
3059         if (i != end_i)
3060                 return -EINVAL;
3061
3062         if (i == 0) {
3063                 offset = start_offset;
3064                 *map_start = 0;
3065         } else {
3066                 offset = 0;
3067                 *map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset;
3068         }
3069         if (start + min_len > eb->len) {
3070 printk("bad mapping eb start %Lu len %lu, wanted %lu %lu\n", eb->start, eb->len, start, min_len);
3071                 WARN_ON(1);
3072         }
3073
3074         p = extent_buffer_page(eb, i);
3075         kaddr = kmap_atomic(p, km);
3076         *token = kaddr;
3077         *map = kaddr + offset;
3078         *map_len = PAGE_CACHE_SIZE - offset;
3079         return 0;
3080 }
3081 EXPORT_SYMBOL(map_private_extent_buffer);
3082
3083 int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
3084                       unsigned long min_len,
3085                       char **token, char **map,
3086                       unsigned long *map_start,
3087                       unsigned long *map_len, int km)
3088 {
3089         int err;
3090         int save = 0;
3091         if (eb->map_token) {
3092                 unmap_extent_buffer(eb, eb->map_token, km);
3093                 eb->map_token = NULL;
3094                 save = 1;
3095         }
3096         err = map_private_extent_buffer(eb, start, min_len, token, map,
3097                                        map_start, map_len, km);
3098         if (!err && save) {
3099                 eb->map_token = *token;
3100                 eb->kaddr = *map;
3101                 eb->map_start = *map_start;
3102                 eb->map_len = *map_len;
3103         }
3104         return err;
3105 }
3106 EXPORT_SYMBOL(map_extent_buffer);
3107
3108 void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km)
3109 {
3110         kunmap_atomic(token, km);
3111 }
3112 EXPORT_SYMBOL(unmap_extent_buffer);
3113
3114 int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
3115                           unsigned long start,
3116                           unsigned long len)
3117 {
3118         size_t cur;
3119         size_t offset;
3120         struct page *page;
3121         char *kaddr;
3122         char *ptr = (char *)ptrv;
3123         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3124         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3125         int ret = 0;
3126
3127         WARN_ON(start > eb->len);
3128         WARN_ON(start + len > eb->start + eb->len);
3129
3130         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3131
3132         while(len > 0) {
3133                 page = extent_buffer_page(eb, i);
3134
3135                 cur = min(len, (PAGE_CACHE_SIZE - offset));
3136
3137                 kaddr = kmap_atomic(page, KM_USER0);
3138                 ret = memcmp(ptr, kaddr + offset, cur);
3139                 kunmap_atomic(kaddr, KM_USER0);
3140                 if (ret)
3141                         break;
3142
3143                 ptr += cur;
3144                 len -= cur;
3145                 offset = 0;
3146                 i++;
3147         }
3148         return ret;
3149 }
3150 EXPORT_SYMBOL(memcmp_extent_buffer);
3151
3152 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
3153                          unsigned long start, unsigned long len)
3154 {
3155         size_t cur;
3156         size_t offset;
3157         struct page *page;
3158         char *kaddr;
3159         char *src = (char *)srcv;
3160         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3161         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3162
3163         WARN_ON(start > eb->len);
3164         WARN_ON(start + len > eb->start + eb->len);
3165
3166         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3167
3168         while(len > 0) {
3169                 page = extent_buffer_page(eb, i);
3170                 WARN_ON(!PageUptodate(page));
3171
3172                 cur = min(len, PAGE_CACHE_SIZE - offset);
3173                 kaddr = kmap_atomic(page, KM_USER1);
3174                 memcpy(kaddr + offset, src, cur);
3175                 kunmap_atomic(kaddr, KM_USER1);
3176
3177                 src += cur;
3178                 len -= cur;
3179                 offset = 0;
3180                 i++;
3181         }
3182 }
3183 EXPORT_SYMBOL(write_extent_buffer);
3184
3185 void memset_extent_buffer(struct extent_buffer *eb, char c,
3186                           unsigned long start, unsigned long len)
3187 {
3188         size_t cur;
3189         size_t offset;
3190         struct page *page;
3191         char *kaddr;
3192         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3193         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3194
3195         WARN_ON(start > eb->len);
3196         WARN_ON(start + len > eb->start + eb->len);
3197
3198         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3199
3200         while(len > 0) {
3201                 page = extent_buffer_page(eb, i);
3202                 WARN_ON(!PageUptodate(page));
3203
3204                 cur = min(len, PAGE_CACHE_SIZE - offset);
3205                 kaddr = kmap_atomic(page, KM_USER0);
3206                 memset(kaddr + offset, c, cur);
3207                 kunmap_atomic(kaddr, KM_USER0);
3208
3209                 len -= cur;
3210                 offset = 0;
3211                 i++;
3212         }
3213 }
3214 EXPORT_SYMBOL(memset_extent_buffer);
3215
3216 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
3217                         unsigned long dst_offset, unsigned long src_offset,
3218                         unsigned long len)
3219 {
3220         u64 dst_len = dst->len;
3221         size_t cur;
3222         size_t offset;
3223         struct page *page;
3224         char *kaddr;
3225         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3226         unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
3227
3228         WARN_ON(src->len != dst_len);
3229
3230         offset = (start_offset + dst_offset) &
3231                 ((unsigned long)PAGE_CACHE_SIZE - 1);
3232
3233         while(len > 0) {
3234                 page = extent_buffer_page(dst, i);
3235                 WARN_ON(!PageUptodate(page));
3236
3237                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
3238
3239                 kaddr = kmap_atomic(page, KM_USER0);
3240                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
3241                 kunmap_atomic(kaddr, KM_USER0);
3242
3243                 src_offset += cur;
3244                 len -= cur;
3245                 offset = 0;
3246                 i++;
3247         }
3248 }
3249 EXPORT_SYMBOL(copy_extent_buffer);
3250
3251 static void move_pages(struct page *dst_page, struct page *src_page,
3252                        unsigned long dst_off, unsigned long src_off,
3253                        unsigned long len)
3254 {
3255         char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
3256         if (dst_page == src_page) {
3257                 memmove(dst_kaddr + dst_off, dst_kaddr + src_off, len);
3258         } else {
3259                 char *src_kaddr = kmap_atomic(src_page, KM_USER1);
3260                 char *p = dst_kaddr + dst_off + len;
3261                 char *s = src_kaddr + src_off + len;
3262
3263                 while (len--)
3264                         *--p = *--s;
3265
3266                 kunmap_atomic(src_kaddr, KM_USER1);
3267         }
3268         kunmap_atomic(dst_kaddr, KM_USER0);
3269 }
3270
3271 static void copy_pages(struct page *dst_page, struct page *src_page,
3272                        unsigned long dst_off, unsigned long src_off,
3273                        unsigned long len)
3274 {
3275         char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
3276         char *src_kaddr;
3277
3278         if (dst_page != src_page)
3279                 src_kaddr = kmap_atomic(src_page, KM_USER1);
3280         else
3281                 src_kaddr = dst_kaddr;
3282
3283         memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
3284         kunmap_atomic(dst_kaddr, KM_USER0);
3285         if (dst_page != src_page)
3286                 kunmap_atomic(src_kaddr, KM_USER1);
3287 }
3288
3289 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
3290                            unsigned long src_offset, unsigned long len)
3291 {
3292         size_t cur;
3293         size_t dst_off_in_page;
3294         size_t src_off_in_page;
3295         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3296         unsigned long dst_i;
3297         unsigned long src_i;
3298
3299         if (src_offset + len > dst->len) {
3300                 printk("memmove bogus src_offset %lu move len %lu len %lu\n",
3301                        src_offset, len, dst->len);
3302                 BUG_ON(1);
3303         }
3304         if (dst_offset + len > dst->len) {
3305                 printk("memmove bogus dst_offset %lu move len %lu len %lu\n",
3306                        dst_offset, len, dst->len);
3307                 BUG_ON(1);
3308         }
3309
3310         while(len > 0) {
3311                 dst_off_in_page = (start_offset + dst_offset) &
3312                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3313                 src_off_in_page = (start_offset + src_offset) &
3314                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3315
3316                 dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
3317                 src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT;
3318
3319                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE -
3320                                                src_off_in_page));
3321                 cur = min_t(unsigned long, cur,
3322                         (unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page));
3323
3324                 copy_pages(extent_buffer_page(dst, dst_i),
3325                            extent_buffer_page(dst, src_i),
3326                            dst_off_in_page, src_off_in_page, cur);
3327
3328                 src_offset += cur;
3329                 dst_offset += cur;
3330                 len -= cur;
3331         }
3332 }
3333 EXPORT_SYMBOL(memcpy_extent_buffer);
3334
3335 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
3336                            unsigned long src_offset, unsigned long len)
3337 {
3338         size_t cur;
3339         size_t dst_off_in_page;
3340         size_t src_off_in_page;
3341         unsigned long dst_end = dst_offset + len - 1;
3342         unsigned long src_end = src_offset + len - 1;
3343         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3344         unsigned long dst_i;
3345         unsigned long src_i;
3346
3347         if (src_offset + len > dst->len) {
3348                 printk("memmove bogus src_offset %lu move len %lu len %lu\n",
3349                        src_offset, len, dst->len);
3350                 BUG_ON(1);
3351         }
3352         if (dst_offset + len > dst->len) {
3353                 printk("memmove bogus dst_offset %lu move len %lu len %lu\n",
3354                        dst_offset, len, dst->len);
3355                 BUG_ON(1);
3356         }
3357         if (dst_offset < src_offset) {
3358                 memcpy_extent_buffer(dst, dst_offset, src_offset, len);
3359                 return;
3360         }
3361         while(len > 0) {
3362                 dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT;
3363                 src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT;
3364
3365                 dst_off_in_page = (start_offset + dst_end) &
3366                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3367                 src_off_in_page = (start_offset + src_end) &
3368                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3369
3370                 cur = min_t(unsigned long, len, src_off_in_page + 1);
3371                 cur = min(cur, dst_off_in_page + 1);
3372                 move_pages(extent_buffer_page(dst, dst_i),
3373                            extent_buffer_page(dst, src_i),
3374                            dst_off_in_page - cur + 1,
3375                            src_off_in_page - cur + 1, cur);
3376
3377                 dst_end -= cur;
3378                 src_end -= cur;
3379                 len -= cur;
3380         }
3381 }
3382 EXPORT_SYMBOL(memmove_extent_buffer);
3383
3384 int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
3385 {
3386         u64 start = page_offset(page);
3387         struct extent_buffer *eb;
3388         int ret = 1;
3389         unsigned long i;
3390         unsigned long num_pages;
3391
3392         spin_lock(&tree->buffer_lock);
3393         eb = buffer_search(tree, start);
3394         if (!eb)
3395                 goto out;
3396
3397         if (atomic_read(&eb->refs) > 1) {
3398                 ret = 0;
3399                 goto out;
3400         }
3401         /* at this point we can safely release the extent buffer */
3402         num_pages = num_extent_pages(eb->start, eb->len);
3403         for (i = 0; i < num_pages; i++) {
3404                 struct page *page = extent_buffer_page(eb, i);
3405                 page_cache_release(page);
3406         }
3407         rb_erase(&eb->rb_node, &tree->buffer);
3408         __free_extent_buffer(eb);
3409 out:
3410         spin_unlock(&tree->buffer_lock);
3411         return ret;
3412 }
3413 EXPORT_SYMBOL(try_release_extent_buffer);