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/writeback.h>
  13 #include <linux/pagevec.h>
  14 #include "extent_io.h"
  15 #include "extent_map.h"
  16 #include "compat.h"
  17 #include "ctree.h"
  18 #include "btrfs_inode.h"
  19
  20 static struct kmem_cache *extent_state_cache;
  21 static struct kmem_cache *extent_buffer_cache;
  22
  23 static LIST_HEAD(buffers);
  24 static LIST_HEAD(states);
  25
  26 #define LEAK_DEBUG 0
  27 #if LEAK_DEBUG
  28 static DEFINE_SPINLOCK(leak_lock);
  29 #endif
  30
  31 #define BUFFER_LRU_MAX 64
  32
  33 struct tree_entry {
  34         u64 start;
  35         u64 end;
  36         struct rb_node rb_node;
  37 };
  38
  39 struct extent_page_data {
  40         struct bio *bio;
  41         struct extent_io_tree *tree;
  42         get_extent_t *get_extent;
  43
  44         /* tells writepage not to lock the state bits for this range
  45          * it still does the unlocking
  46          */
  47         unsigned int extent_locked:1;
  48
  49         /* tells the submit_bio code to use a WRITE_SYNC */
  50         unsigned int sync_io:1;
  51 };
  52
  53 int __init extent_io_init(void)
  54 {
  55         extent_state_cache = kmem_cache_create("extent_state",
  56                         sizeof(struct extent_state), 0,
  57                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
  58         if (!extent_state_cache)
  59                 return -ENOMEM;
  60
  61         extent_buffer_cache = kmem_cache_create("extent_buffers",
  62                         sizeof(struct extent_buffer), 0,
  63                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
  64         if (!extent_buffer_cache)
  65                 goto free_state_cache;
  66         return 0;
  67
  68 free_state_cache:
  69         kmem_cache_destroy(extent_state_cache);
  70         return -ENOMEM;
  71 }
  72
  73 void extent_io_exit(void)
  74 {
  75         struct extent_state *state;
  76         struct extent_buffer *eb;
  77
  78         while (!list_empty(&states)) {
  79                 state = list_entry(states.next, struct extent_state, leak_list);
  80                 printk(KERN_ERR "btrfs state leak: start %llu end %llu "
  81                        "state %lu in tree %p refs %d\n",
  82                        (unsigned long long)state->start,
  83                        (unsigned long long)state->end,
  84                        state->state, state->tree, atomic_read(&state->refs));
  85                 list_del(&state->leak_list);
  86                 kmem_cache_free(extent_state_cache, state);
  87
  88         }
  89
  90         while (!list_empty(&buffers)) {
  91                 eb = list_entry(buffers.next, struct extent_buffer, leak_list);
  92                 printk(KERN_ERR "btrfs buffer leak start %llu len %lu "
  93                        "refs %d\n", (unsigned long long)eb->start,
  94                        eb->len, atomic_read(&eb->refs));
  95                 list_del(&eb->leak_list);
  96                 kmem_cache_free(extent_buffer_cache, eb);
  97         }
  98         if (extent_state_cache)
  99                 kmem_cache_destroy(extent_state_cache);
 100         if (extent_buffer_cache)
 101                 kmem_cache_destroy(extent_buffer_cache);
 102 }
 103
 104 void extent_io_tree_init(struct extent_io_tree *tree,
 105                           struct address_space *mapping, gfp_t mask)
 106 {
 107         tree->state.rb_node = NULL;
 108         tree->buffer.rb_node = NULL;
 109         tree->ops = NULL;
 110         tree->dirty_bytes = 0;
 111         spin_lock_init(&tree->lock);
 112         spin_lock_init(&tree->buffer_lock);
 113         tree->mapping = mapping;
 114 }
 115
 116 static struct extent_state *alloc_extent_state(gfp_t mask)
 117 {
 118         struct extent_state *state;
 119 #if LEAK_DEBUG
 120         unsigned long flags;
 121 #endif
 122
 123         state = kmem_cache_alloc(extent_state_cache, mask);
 124         if (!state)
 125                 return state;
 126         state->state = 0;
 127         state->private = 0;
 128         state->tree = NULL;
 129 #if LEAK_DEBUG
 130         spin_lock_irqsave(&leak_lock, flags);
 131         list_add(&state->leak_list, &states);
 132         spin_unlock_irqrestore(&leak_lock, flags);
 133 #endif
 134         atomic_set(&state->refs, 1);
 135         init_waitqueue_head(&state->wq);
 136         return state;
 137 }
 138
 139 static void free_extent_state(struct extent_state *state)
 140 {
 141         if (!state)
 142                 return;
 143         if (atomic_dec_and_test(&state->refs)) {
 144 #if LEAK_DEBUG
 145                 unsigned long flags;
 146 #endif
 147                 WARN_ON(state->tree);
 148 #if LEAK_DEBUG
 149                 spin_lock_irqsave(&leak_lock, flags);
 150                 list_del(&state->leak_list);
 151                 spin_unlock_irqrestore(&leak_lock, flags);
 152 #endif
 153                 kmem_cache_free(extent_state_cache, state);
 154         }
 155 }
 156
 157 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
 158                                    struct rb_node *node)
 159 {
 160         struct rb_node **p = &root->rb_node;
 161         struct rb_node *parent = NULL;
 162         struct tree_entry *entry;
 163
 164         while (*p) {
 165                 parent = *p;
 166                 entry = rb_entry(parent, struct tree_entry, rb_node);
 167
 168                 if (offset < entry->start)
 169                         p = &(*p)->rb_left;
 170                 else if (offset > entry->end)
 171                         p = &(*p)->rb_right;
 172                 else
 173                         return parent;
 174         }
 175
 176         entry = rb_entry(node, struct tree_entry, rb_node);
 177         rb_link_node(node, parent, p);
 178         rb_insert_color(node, root);
 179         return NULL;
 180 }
 181
 182 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 183                                      struct rb_node **prev_ret,
 184                                      struct rb_node **next_ret)
 185 {
 186         struct rb_root *root = &tree->state;
 187         struct rb_node *n = root->rb_node;
 188         struct rb_node *prev = NULL;
 189         struct rb_node *orig_prev = NULL;
 190         struct tree_entry *entry;
 191         struct tree_entry *prev_entry = NULL;
 192
 193         while (n) {
 194                 entry = rb_entry(n, struct tree_entry, rb_node);
 195                 prev = n;
 196                 prev_entry = entry;
 197
 198                 if (offset < entry->start)
 199                         n = n->rb_left;
 200                 else if (offset > entry->end)
 201                         n = n->rb_right;
 202                 else
 203                         return n;
 204         }
 205
 206         if (prev_ret) {
 207                 orig_prev = prev;
 208                 while (prev && offset > prev_entry->end) {
 209                         prev = rb_next(prev);
 210                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 211                 }
 212                 *prev_ret = prev;
 213                 prev = orig_prev;
 214         }
 215
 216         if (next_ret) {
 217                 prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 218                 while (prev && offset < prev_entry->start) {
 219                         prev = rb_prev(prev);
 220                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 221                 }
 222                 *next_ret = prev;
 223         }
 224         return NULL;
 225 }
 226
 227 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
 228                                           u64 offset)
 229 {
 230         struct rb_node *prev = NULL;
 231         struct rb_node *ret;
 232
 233         ret = __etree_search(tree, offset, &prev, NULL);
 234         if (!ret)
 235                 return prev;
 236         return ret;
 237 }
 238
 239 static struct extent_buffer *buffer_tree_insert(struct extent_io_tree *tree,
 240                                           u64 offset, struct rb_node *node)
 241 {
 242         struct rb_root *root = &tree->buffer;
 243         struct rb_node **p = &root->rb_node;
 244         struct rb_node *parent = NULL;
 245         struct extent_buffer *eb;
 246
 247         while (*p) {
 248                 parent = *p;
 249                 eb = rb_entry(parent, struct extent_buffer, rb_node);
 250
 251                 if (offset < eb->start)
 252                         p = &(*p)->rb_left;
 253                 else if (offset > eb->start)
 254                         p = &(*p)->rb_right;
 255                 else
 256                         return eb;
 257         }
 258
 259         rb_link_node(node, parent, p);
 260         rb_insert_color(node, root);
 261         return NULL;
 262 }
 263
 264 static struct extent_buffer *buffer_search(struct extent_io_tree *tree,
 265                                            u64 offset)
 266 {
 267         struct rb_root *root = &tree->buffer;
 268         struct rb_node *n = root->rb_node;
 269         struct extent_buffer *eb;
 270
 271         while (n) {
 272                 eb = rb_entry(n, struct extent_buffer, rb_node);
 273                 if (offset < eb->start)
 274                         n = n->rb_left;
 275                 else if (offset > eb->start)
 276                         n = n->rb_right;
 277                 else
 278                         return eb;
 279         }
 280         return NULL;
 281 }
 282
 283 static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
 284                      struct extent_state *other)
 285 {
 286         if (tree->ops && tree->ops->merge_extent_hook)
 287                 tree->ops->merge_extent_hook(tree->mapping->host, new,
 288                                              other);
 289 }
 290
 291 /*
 292  * utility function to look for merge candidates inside a given range.
 293  * Any extents with matching state are merged together into a single
 294  * extent in the tree.  Extents with EXTENT_IO in their state field
 295  * are not merged because the end_io handlers need to be able to do
 296  * operations on them without sleeping (or doing allocations/splits).
 297  *
 298  * This should be called with the tree lock held.
 299  */
 300 static int merge_state(struct extent_io_tree *tree,
 301                        struct extent_state *state)
 302 {
 303         struct extent_state *other;
 304         struct rb_node *other_node;
 305
 306         if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 307                 return 0;
 308
 309         other_node = rb_prev(&state->rb_node);
 310         if (other_node) {
 311                 other = rb_entry(other_node, struct extent_state, rb_node);
 312                 if (other->end == state->start - 1 &&
 313                     other->state == state->state) {
 314                         merge_cb(tree, state, other);
 315                         state->start = other->start;
 316                         other->tree = NULL;
 317                         rb_erase(&other->rb_node, &tree->state);
 318                         free_extent_state(other);
 319                 }
 320         }
 321         other_node = rb_next(&state->rb_node);
 322         if (other_node) {
 323                 other = rb_entry(other_node, struct extent_state, rb_node);
 324                 if (other->start == state->end + 1 &&
 325                     other->state == state->state) {
 326                         merge_cb(tree, state, other);
 327                         other->start = state->start;
 328                         state->tree = NULL;
 329                         rb_erase(&state->rb_node, &tree->state);
 330                         free_extent_state(state);
 331                         state = NULL;
 332                 }
 333         }
 334
 335         return 0;
 336 }
 337
 338 static int set_state_cb(struct extent_io_tree *tree,
 339                          struct extent_state *state,
 340                          unsigned long bits)
 341 {
 342         if (tree->ops && tree->ops->set_bit_hook) {
 343                 return tree->ops->set_bit_hook(tree->mapping->host,
 344                                                state->start, state->end,
 345                                                state->state, bits);
 346         }
 347
 348         return 0;
 349 }
 350
 351 static void clear_state_cb(struct extent_io_tree *tree,
 352                            struct extent_state *state,
 353                            unsigned long bits)
 354 {
 355         if (tree->ops && tree->ops->clear_bit_hook)
 356                 tree->ops->clear_bit_hook(tree->mapping->host, state, bits);
 357 }
 358
 359 /*
 360  * insert an extent_state struct into the tree.  'bits' are set on the
 361  * struct before it is inserted.
 362  *
 363  * This may return -EEXIST if the extent is already there, in which case the
 364  * state struct is freed.
 365  *
 366  * The tree lock is not taken internally.  This is a utility function and
 367  * probably isn't what you want to call (see set/clear_extent_bit).
 368  */
 369 static int insert_state(struct extent_io_tree *tree,
 370                         struct extent_state *state, u64 start, u64 end,
 371                         int bits)
 372 {
 373         struct rb_node *node;
 374         int ret;
 375
 376         if (end < start) {
 377                 printk(KERN_ERR "btrfs end < start %llu %llu\n",
 378                        (unsigned long long)end,
 379                        (unsigned long long)start);
 380                 WARN_ON(1);
 381         }
 382         state->start = start;
 383         state->end = end;
 384         ret = set_state_cb(tree, state, bits);
 385         if (ret)
 386                 return ret;
 387
 388         if (bits & EXTENT_DIRTY)
 389                 tree->dirty_bytes += end - start + 1;
 390         state->state |= bits;
 391         node = tree_insert(&tree->state, end, &state->rb_node);
 392         if (node) {
 393                 struct extent_state *found;
 394                 found = rb_entry(node, struct extent_state, rb_node);
 395                 printk(KERN_ERR "btrfs found node %llu %llu on insert of "
 396                        "%llu %llu\n", (unsigned long long)found->start,
 397                        (unsigned long long)found->end,
 398                        (unsigned long long)start, (unsigned long long)end);
 399                 free_extent_state(state);
 400                 return -EEXIST;
 401         }
 402         state->tree = tree;
 403         merge_state(tree, state);
 404         return 0;
 405 }
 406
 407 static int split_cb(struct extent_io_tree *tree, struct extent_state *orig,
 408                      u64 split)
 409 {
 410         if (tree->ops && tree->ops->split_extent_hook)
 411                 return tree->ops->split_extent_hook(tree->mapping->host,
 412                                                     orig, split);
 413         return 0;
 414 }
 415
 416 /*
 417  * split a given extent state struct in two, inserting the preallocated
 418  * struct 'prealloc' as the newly created second half.  'split' indicates an
 419  * offset inside 'orig' where it should be split.
 420  *
 421  * Before calling,
 422  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
 423  * are two extent state structs in the tree:
 424  * prealloc: [orig->start, split - 1]
 425  * orig: [ split, orig->end ]
 426  *
 427  * The tree locks are not taken by this function. They need to be held
 428  * by the caller.
 429  */
 430 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 431                        struct extent_state *prealloc, u64 split)
 432 {
 433         struct rb_node *node;
 434
 435         split_cb(tree, orig, split);
 436
 437         prealloc->start = orig->start;
 438         prealloc->end = split - 1;
 439         prealloc->state = orig->state;
 440         orig->start = split;
 441
 442         node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node);
 443         if (node) {
 444                 free_extent_state(prealloc);
 445                 return -EEXIST;
 446         }
 447         prealloc->tree = tree;
 448         return 0;
 449 }
 450
 451 /*
 452  * utility function to clear some bits in an extent state struct.
 453  * it will optionally wake up any one waiting on this state (wake == 1), or
 454  * forcibly remove the state from the tree (delete == 1).
 455  *
 456  * If no bits are set on the state struct after clearing things, the
 457  * struct is freed and removed from the tree
 458  */
 459 static int clear_state_bit(struct extent_io_tree *tree,
 460                             struct extent_state *state, int bits, int wake,
 461                             int delete)
 462 {
 463         int ret = state->state & bits;
 464
 465         if ((bits & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
 466                 u64 range = state->end - state->start + 1;
 467                 WARN_ON(range > tree->dirty_bytes);
 468                 tree->dirty_bytes -= range;
 469         }
 470         clear_state_cb(tree, state, bits);
 471         state->state &= ~bits;
 472         if (wake)
 473                 wake_up(&state->wq);
 474         if (delete || state->state == 0) {
 475                 if (state->tree) {
 476                         clear_state_cb(tree, state, state->state);
 477                         rb_erase(&state->rb_node, &tree->state);
 478                         state->tree = NULL;
 479                         free_extent_state(state);
 480                 } else {
 481                         WARN_ON(1);
 482                 }
 483         } else {
 484                 merge_state(tree, state);
 485         }
 486         return ret;
 487 }
 488
 489 /*
 490  * clear some bits on a range in the tree.  This may require splitting
 491  * or inserting elements in the tree, so the gfp mask is used to
 492  * indicate which allocations or sleeping are allowed.
 493  *
 494  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
 495  * the given range from the tree regardless of state (ie for truncate).
 496  *
 497  * the range [start, end] is inclusive.
 498  *
 499  * This takes the tree lock, and returns < 0 on error, > 0 if any of the
 500  * bits were already set, or zero if none of the bits were already set.
 501  */
 502 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 503                      int bits, int wake, int delete,
 504                      struct extent_state **cached_state,
 505                      gfp_t mask)
 506 {
 507         struct extent_state *state;
 508         struct extent_state *cached;
 509         struct extent_state *prealloc = NULL;
 510         struct rb_node *next_node;
 511         struct rb_node *node;
 512         u64 last_end;
 513         int err;
 514         int set = 0;
 515
 516 again:
 517         if (!prealloc && (mask & __GFP_WAIT)) {
 518                 prealloc = alloc_extent_state(mask);
 519                 if (!prealloc)
 520                         return -ENOMEM;
 521         }
 522
 523         spin_lock(&tree->lock);
 524         if (cached_state) {
 525                 cached = *cached_state;
 526                 *cached_state = NULL;
 527                 cached_state = NULL;
 528                 if (cached && cached->tree && cached->start == start) {
 529                         atomic_dec(&cached->refs);
 530                         state = cached;
 531                         goto hit_next;
 532                 }
 533                 free_extent_state(cached);
 534         }
 535         /*
 536          * this search will find the extents that end after
 537          * our range starts
 538          */
 539         node = tree_search(tree, start);
 540         if (!node)
 541                 goto out;
 542         state = rb_entry(node, struct extent_state, rb_node);
 543 hit_next:
 544         if (state->start > end)
 545                 goto out;
 546         WARN_ON(state->end < start);
 547         last_end = state->end;
 548
 549         /*
 550          *     | ---- desired range ---- |
 551          *  | state | or
 552          *  | ------------- state -------------- |
 553          *
 554          * We need to split the extent we found, and may flip
 555          * bits on second half.
 556          *
 557          * If the extent we found extends past our range, we
 558          * just split and search again.  It'll get split again
 559          * the next time though.
 560          *
 561          * If the extent we found is inside our range, we clear
 562          * the desired bit on it.
 563          */
 564
 565         if (state->start < start) {
 566                 if (!prealloc)
 567                         prealloc = alloc_extent_state(GFP_ATOMIC);
 568                 err = split_state(tree, state, prealloc, start);
 569                 BUG_ON(err == -EEXIST);
 570                 prealloc = NULL;
 571                 if (err)
 572                         goto out;
 573                 if (state->end <= end) {
 574                         set |= clear_state_bit(tree, state, bits, wake,
 575                                                delete);
 576                         if (last_end == (u64)-1)
 577                                 goto out;
 578                         start = last_end + 1;
 579                 }
 580                 goto search_again;
 581         }
 582         /*
 583          * | ---- desired range ---- |
 584          *                        | state |
 585          * We need to split the extent, and clear the bit
 586          * on the first half
 587          */
 588         if (state->start <= end && state->end > end) {
 589                 if (!prealloc)
 590                         prealloc = alloc_extent_state(GFP_ATOMIC);
 591                 err = split_state(tree, state, prealloc, end + 1);
 592                 BUG_ON(err == -EEXIST);
 593                 if (wake)
 594                         wake_up(&state->wq);
 595
 596                 set |= clear_state_bit(tree, prealloc, bits, wake, delete);
 597
 598                 prealloc = NULL;
 599                 goto out;
 600         }
 601
 602         if (state->end < end && prealloc && !need_resched())
 603                 next_node = rb_next(&state->rb_node);
 604         else
 605                 next_node = NULL;
 606
 607         set |= clear_state_bit(tree, state, bits, wake, delete);
 608         if (last_end == (u64)-1)
 609                 goto out;
 610         start = last_end + 1;
 611         if (start <= end && next_node) {
 612                 state = rb_entry(next_node, struct extent_state,
 613                                  rb_node);
 614                 if (state->start == start)
 615                         goto hit_next;
 616         }
 617         goto search_again;
 618
 619 out:
 620         spin_unlock(&tree->lock);
 621         if (prealloc)
 622                 free_extent_state(prealloc);
 623
 624         return set;
 625
 626 search_again:
 627         if (start > end)
 628                 goto out;
 629         spin_unlock(&tree->lock);
 630         if (mask & __GFP_WAIT)
 631                 cond_resched();
 632         goto again;
 633 }
 634
 635 static int wait_on_state(struct extent_io_tree *tree,
 636                          struct extent_state *state)
 637                 __releases(tree->lock)
 638                 __acquires(tree->lock)
 639 {
 640         DEFINE_WAIT(wait);
 641         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
 642         spin_unlock(&tree->lock);
 643         schedule();
 644         spin_lock(&tree->lock);
 645         finish_wait(&state->wq, &wait);
 646         return 0;
 647 }
 648
 649 /*
 650  * waits for one or more bits to clear on a range in the state tree.
 651  * The range [start, end] is inclusive.
 652  * The tree lock is taken by this function
 653  */
 654 int wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, int bits)
 655 {
 656         struct extent_state *state;
 657         struct rb_node *node;
 658
 659         spin_lock(&tree->lock);
 660 again:
 661         while (1) {
 662                 /*
 663                  * this search will find all the extents that end after
 664                  * our range starts
 665                  */
 666                 node = tree_search(tree, start);
 667                 if (!node)
 668                         break;
 669
 670                 state = rb_entry(node, struct extent_state, rb_node);
 671
 672                 if (state->start > end)
 673                         goto out;
 674
 675                 if (state->state & bits) {
 676                         start = state->start;
 677                         atomic_inc(&state->refs);
 678                         wait_on_state(tree, state);
 679                         free_extent_state(state);
 680                         goto again;
 681                 }
 682                 start = state->end + 1;
 683
 684                 if (start > end)
 685                         break;
 686
 687                 if (need_resched()) {
 688                         spin_unlock(&tree->lock);
 689                         cond_resched();
 690                         spin_lock(&tree->lock);
 691                 }
 692         }
 693 out:
 694         spin_unlock(&tree->lock);
 695         return 0;
 696 }
 697
 698 static int set_state_bits(struct extent_io_tree *tree,
 699                            struct extent_state *state,
 700                            int bits)
 701 {
 702         int ret;
 703
 704         ret = set_state_cb(tree, state, bits);
 705         if (ret)
 706                 return ret;
 707
 708         if ((bits & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
 709                 u64 range = state->end - state->start + 1;
 710                 tree->dirty_bytes += range;
 711         }
 712         state->state |= bits;
 713
 714         return 0;
 715 }
 716
 717 static void cache_state(struct extent_state *state,
 718                         struct extent_state **cached_ptr)
 719 {
 720         if (cached_ptr && !(*cached_ptr)) {
 721                 if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY)) {
 722                         *cached_ptr = state;
 723                         atomic_inc(&state->refs);
 724                 }
 725         }
 726 }
 727
 728 /*
 729  * set some bits on a range in the tree.  This may require allocations or
 730  * sleeping, so the gfp mask is used to indicate what is allowed.
 731  *
 732  * If any of the exclusive bits are set, this will fail with -EEXIST if some
 733  * part of the range already has the desired bits set.  The start of the
 734  * existing range is returned in failed_start in this case.
 735  *
 736  * [start, end] is inclusive This takes the tree lock.
 737  */
 738
 739 static int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 740                           int bits, int exclusive_bits, u64 *failed_start,
 741                           struct extent_state **cached_state,
 742                           gfp_t mask)
 743 {
 744         struct extent_state *state;
 745         struct extent_state *prealloc = NULL;
 746         struct rb_node *node;
 747         int err = 0;
 748         u64 last_start;
 749         u64 last_end;
 750
 751 again:
 752         if (!prealloc && (mask & __GFP_WAIT)) {
 753                 prealloc = alloc_extent_state(mask);
 754                 if (!prealloc)
 755                         return -ENOMEM;
 756         }
 757
 758         spin_lock(&tree->lock);
 759         if (cached_state && *cached_state) {
 760                 state = *cached_state;
 761                 if (state->start == start && state->tree) {
 762                         node = &state->rb_node;
 763                         goto hit_next;
 764                 }
 765         }
 766         /*
 767          * this search will find all the extents that end after
 768          * our range starts.
 769          */
 770         node = tree_search(tree, start);
 771         if (!node) {
 772                 err = insert_state(tree, prealloc, start, end, bits);
 773                 prealloc = NULL;
 774                 BUG_ON(err == -EEXIST);
 775                 goto out;
 776         }
 777         state = rb_entry(node, struct extent_state, rb_node);
 778 hit_next:
 779         last_start = state->start;
 780         last_end = state->end;
 781
 782         /*
 783          * | ---- desired range ---- |
 784          * | state |
 785          *
 786          * Just lock what we found and keep going
 787          */
 788         if (state->start == start && state->end <= end) {
 789                 struct rb_node *next_node;
 790                 if (state->state & exclusive_bits) {
 791                         *failed_start = state->start;
 792                         err = -EEXIST;
 793                         goto out;
 794                 }
 795
 796                 err = set_state_bits(tree, state, bits);
 797                 if (err)
 798                         goto out;
 799
 800                 cache_state(state, cached_state);
 801                 merge_state(tree, state);
 802                 if (last_end == (u64)-1)
 803                         goto out;
 804
 805                 start = last_end + 1;
 806                 if (start < end && prealloc && !need_resched()) {
 807                         next_node = rb_next(node);
 808                         if (next_node) {
 809                                 state = rb_entry(next_node, struct extent_state,
 810                                                  rb_node);
 811                                 if (state->start == start)
 812                                         goto hit_next;
 813                         }
 814                 }
 815                 goto search_again;
 816         }
 817
 818         /*
 819          *     | ---- desired range ---- |
 820          * | state |
 821          *   or
 822          * | ------------- state -------------- |
 823          *
 824          * We need to split the extent we found, and may flip bits on
 825          * second half.
 826          *
 827          * If the extent we found extends past our
 828          * range, we just split and search again.  It'll get split
 829          * again the next time though.
 830          *
 831          * If the extent we found is inside our range, we set the
 832          * desired bit on it.
 833          */
 834         if (state->start < start) {
 835                 if (state->state & exclusive_bits) {
 836                         *failed_start = start;
 837                         err = -EEXIST;
 838                         goto out;
 839                 }
 840                 err = split_state(tree, state, prealloc, start);
 841                 BUG_ON(err == -EEXIST);
 842                 prealloc = NULL;
 843                 if (err)
 844                         goto out;
 845                 if (state->end <= end) {
 846                         err = set_state_bits(tree, state, bits);
 847                         if (err)
 848                                 goto out;
 849                         cache_state(state, cached_state);
 850                         merge_state(tree, state);
 851                         if (last_end == (u64)-1)
 852                                 goto out;
 853                         start = last_end + 1;
 854                 }
 855                 goto search_again;
 856         }
 857         /*
 858          * | ---- desired range ---- |
 859          *     | state | or               | state |
 860          *
 861          * There's a hole, we need to insert something in it and
 862          * ignore the extent we found.
 863          */
 864         if (state->start > start) {
 865                 u64 this_end;
 866                 if (end < last_start)
 867                         this_end = end;
 868                 else
 869                         this_end = last_start - 1;
 870                 err = insert_state(tree, prealloc, start, this_end,
 871                                    bits);
 872                 BUG_ON(err == -EEXIST);
 873                 if (err) {
 874                         prealloc = NULL;
 875                         goto out;
 876                 }
 877                 cache_state(prealloc, cached_state);
 878                 prealloc = NULL;
 879                 start = this_end + 1;
 880                 goto search_again;
 881         }
 882         /*
 883          * | ---- desired range ---- |
 884          *                        | state |
 885          * We need to split the extent, and set the bit
 886          * on the first half
 887          */
 888         if (state->start <= end && state->end > end) {
 889                 if (state->state & exclusive_bits) {
 890                         *failed_start = start;
 891                         err = -EEXIST;
 892                         goto out;
 893                 }
 894                 err = split_state(tree, state, prealloc, end + 1);
 895                 BUG_ON(err == -EEXIST);
 896
 897                 err = set_state_bits(tree, prealloc, bits);
 898                 if (err) {
 899                         prealloc = NULL;
 900                         goto out;
 901                 }
 902                 cache_state(prealloc, cached_state);
 903                 merge_state(tree, prealloc);
 904                 prealloc = NULL;
 905                 goto out;
 906         }
 907
 908         goto search_again;
 909
 910 out:
 911         spin_unlock(&tree->lock);
 912         if (prealloc)
 913                 free_extent_state(prealloc);
 914
 915         return err;
 916
 917 search_again:
 918         if (start > end)
 919                 goto out;
 920         spin_unlock(&tree->lock);
 921         if (mask & __GFP_WAIT)
 922                 cond_resched();
 923         goto again;
 924 }
 925
 926 /* wrappers around set/clear extent bit */
 927 int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
 928                      gfp_t mask)
 929 {
 930         return set_extent_bit(tree, start, end, EXTENT_DIRTY, 0, NULL,
 931                               NULL, mask);
 932 }
 933
 934 int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 935                     int bits, gfp_t mask)
 936 {
 937         return set_extent_bit(tree, start, end, bits, 0, NULL,
 938                               NULL, mask);
 939 }
 940
 941 int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 942                       int bits, gfp_t mask)
 943 {
 944         return clear_extent_bit(tree, start, end, bits, 0, 0, NULL, mask);
 945 }
 946
 947 int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
 948                      gfp_t mask)
 949 {
 950         return set_extent_bit(tree, start, end,
 951                               EXTENT_DELALLOC | EXTENT_DIRTY | EXTENT_UPTODATE,
 952                               0, NULL, NULL, mask);
 953 }
 954
 955 int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
 956                        gfp_t mask)
 957 {
 958         return clear_extent_bit(tree, start, end,
 959                                 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
 960                                 NULL, mask);
 961 }
 962
 963 int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
 964                      gfp_t mask)
 965 {
 966         return set_extent_bit(tree, start, end, EXTENT_NEW, 0, NULL,
 967                               NULL, mask);
 968 }
 969
 970 static int clear_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
 971                        gfp_t mask)
 972 {
 973         return clear_extent_bit(tree, start, end, EXTENT_NEW, 0, 0,
 974                                 NULL, mask);
 975 }
 976
 977 int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
 978                         gfp_t mask)
 979 {
 980         return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL,
 981                               NULL, mask);
 982 }
 983
 984 static int clear_extent_uptodate(struct extent_io_tree *tree, u64 start,
 985                                  u64 end, gfp_t mask)
 986 {
 987         return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
 988                                 NULL, mask);
 989 }
 990
 991 int wait_on_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end)
 992 {
 993         return wait_extent_bit(tree, start, end, EXTENT_WRITEBACK);
 994 }
 995
 996 /*
 997  * either insert or lock state struct between start and end use mask to tell
 998  * us if waiting is desired.
 999  */
1000 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1001                      int bits, struct extent_state **cached_state, gfp_t mask)
1002 {
1003         int err;
1004         u64 failed_start;
1005         while (1) {
1006                 err = set_extent_bit(tree, start, end, EXTENT_LOCKED | bits,
1007                                      EXTENT_LOCKED, &failed_start,
1008                                      cached_state, mask);
1009                 if (err == -EEXIST && (mask & __GFP_WAIT)) {
1010                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1011                         start = failed_start;
1012                 } else {
1013                         break;
1014                 }
1015                 WARN_ON(start > end);
1016         }
1017         return err;
1018 }
1019
1020 int lock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask)
1021 {
1022         return lock_extent_bits(tree, start, end, 0, NULL, mask);
1023 }
1024
1025 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end,
1026                     gfp_t mask)
1027 {
1028         int err;
1029         u64 failed_start;
1030
1031         err = set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1032                              &failed_start, NULL, mask);
1033         if (err == -EEXIST) {
1034                 if (failed_start > start)
1035                         clear_extent_bit(tree, start, failed_start - 1,
1036                                          EXTENT_LOCKED, 1, 0, NULL, mask);
1037                 return 0;
1038         }
1039         return 1;
1040 }
1041
1042 int unlock_extent_cached(struct extent_io_tree *tree, u64 start, u64 end,
1043                          struct extent_state **cached, gfp_t mask)
1044 {
1045         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
1046                                 mask);
1047 }
1048
1049 int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end,
1050                   gfp_t mask)
1051 {
1052         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL,
1053                                 mask);
1054 }
1055
1056 /*
1057  * helper function to set pages and extents in the tree dirty
1058  */
1059 int set_range_dirty(struct extent_io_tree *tree, u64 start, u64 end)
1060 {
1061         unsigned long index = start >> PAGE_CACHE_SHIFT;
1062         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1063         struct page *page;
1064
1065         while (index <= end_index) {
1066                 page = find_get_page(tree->mapping, index);
1067                 BUG_ON(!page);
1068                 __set_page_dirty_nobuffers(page);
1069                 page_cache_release(page);
1070                 index++;
1071         }
1072         return 0;
1073 }
1074
1075 /*
1076  * helper function to set both pages and extents in the tree writeback
1077  */
1078 static int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1079 {
1080         unsigned long index = start >> PAGE_CACHE_SHIFT;
1081         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1082         struct page *page;
1083
1084         while (index <= end_index) {
1085                 page = find_get_page(tree->mapping, index);
1086                 BUG_ON(!page);
1087                 set_page_writeback(page);
1088                 page_cache_release(page);
1089                 index++;
1090         }
1091         return 0;
1092 }
1093
1094 /*
1095  * find the first offset in the io tree with 'bits' set. zero is
1096  * returned if we find something, and *start_ret and *end_ret are
1097  * set to reflect the state struct that was found.
1098  *
1099  * If nothing was found, 1 is returned, < 0 on error
1100  */
1101 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1102                           u64 *start_ret, u64 *end_ret, int bits)
1103 {
1104         struct rb_node *node;
1105         struct extent_state *state;
1106         int ret = 1;
1107
1108         spin_lock(&tree->lock);
1109         /*
1110          * this search will find all the extents that end after
1111          * our range starts.
1112          */
1113         node = tree_search(tree, start);
1114         if (!node)
1115                 goto out;
1116
1117         while (1) {
1118                 state = rb_entry(node, struct extent_state, rb_node);
1119                 if (state->end >= start && (state->state & bits)) {
1120                         *start_ret = state->start;
1121                         *end_ret = state->end;
1122                         ret = 0;
1123                         break;
1124                 }
1125                 node = rb_next(node);
1126                 if (!node)
1127                         break;
1128         }
1129 out:
1130         spin_unlock(&tree->lock);
1131         return ret;
1132 }
1133
1134 /* find the first state struct with 'bits' set after 'start', and
1135  * return it.  tree->lock must be held.  NULL will returned if
1136  * nothing was found after 'start'
1137  */
1138 struct extent_state *find_first_extent_bit_state(struct extent_io_tree *tree,
1139                                                  u64 start, int bits)
1140 {
1141         struct rb_node *node;
1142         struct extent_state *state;
1143
1144         /*
1145          * this search will find all the extents that end after
1146          * our range starts.
1147          */
1148         node = tree_search(tree, start);
1149         if (!node)
1150                 goto out;
1151
1152         while (1) {
1153                 state = rb_entry(node, struct extent_state, rb_node);
1154                 if (state->end >= start && (state->state & bits))
1155                         return state;
1156
1157                 node = rb_next(node);
1158                 if (!node)
1159                         break;
1160         }
1161 out:
1162         return NULL;
1163 }
1164
1165 /*
1166  * find a contiguous range of bytes in the file marked as delalloc, not
1167  * more than 'max_bytes'.  start and end are used to return the range,
1168  *
1169  * 1 is returned if we find something, 0 if nothing was in the tree
1170  */
1171 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
1172                                         u64 *start, u64 *end, u64 max_bytes)
1173 {
1174         struct rb_node *node;
1175         struct extent_state *state;
1176         u64 cur_start = *start;
1177         u64 found = 0;
1178         u64 total_bytes = 0;
1179
1180         spin_lock(&tree->lock);
1181
1182         /*
1183          * this search will find all the extents that end after
1184          * our range starts.
1185          */
1186         node = tree_search(tree, cur_start);
1187         if (!node) {
1188                 if (!found)
1189                         *end = (u64)-1;
1190                 goto out;
1191         }
1192
1193         while (1) {
1194                 state = rb_entry(node, struct extent_state, rb_node);
1195                 if (found && (state->start != cur_start ||
1196                               (state->state & EXTENT_BOUNDARY))) {
1197                         goto out;
1198                 }
1199                 if (!(state->state & EXTENT_DELALLOC)) {
1200                         if (!found)
1201                                 *end = state->end;
1202                         goto out;
1203                 }
1204                 if (!found)
1205                         *start = state->start;
1206                 found++;
1207                 *end = state->end;
1208                 cur_start = state->end + 1;
1209                 node = rb_next(node);
1210                 if (!node)
1211                         break;
1212                 total_bytes += state->end - state->start + 1;
1213                 if (total_bytes >= max_bytes)
1214                         break;
1215         }
1216 out:
1217         spin_unlock(&tree->lock);
1218         return found;
1219 }
1220
1221 static noinline int __unlock_for_delalloc(struct inode *inode,
1222                                           struct page *locked_page,
1223                                           u64 start, u64 end)
1224 {
1225         int ret;
1226         struct page *pages[16];
1227         unsigned long index = start >> PAGE_CACHE_SHIFT;
1228         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1229         unsigned long nr_pages = end_index - index + 1;
1230         int i;
1231
1232         if (index == locked_page->index && end_index == index)
1233                 return 0;
1234
1235         while (nr_pages > 0) {
1236                 ret = find_get_pages_contig(inode->i_mapping, index,
1237                                      min_t(unsigned long, nr_pages,
1238                                      ARRAY_SIZE(pages)), pages);
1239                 for (i = 0; i < ret; i++) {
1240                         if (pages[i] != locked_page)
1241                                 unlock_page(pages[i]);
1242                         page_cache_release(pages[i]);
1243                 }
1244                 nr_pages -= ret;
1245                 index += ret;
1246                 cond_resched();
1247         }
1248         return 0;
1249 }
1250
1251 static noinline int lock_delalloc_pages(struct inode *inode,
1252                                         struct page *locked_page,
1253                                         u64 delalloc_start,
1254                                         u64 delalloc_end)
1255 {
1256         unsigned long index = delalloc_start >> PAGE_CACHE_SHIFT;
1257         unsigned long start_index = index;
1258         unsigned long end_index = delalloc_end >> PAGE_CACHE_SHIFT;
1259         unsigned long pages_locked = 0;
1260         struct page *pages[16];
1261         unsigned long nrpages;
1262         int ret;
1263         int i;
1264
1265         /* the caller is responsible for locking the start index */
1266         if (index == locked_page->index && index == end_index)
1267                 return 0;
1268
1269         /* skip the page at the start index */
1270         nrpages = end_index - index + 1;
1271         while (nrpages > 0) {
1272                 ret = find_get_pages_contig(inode->i_mapping, index,
1273                                      min_t(unsigned long,
1274                                      nrpages, ARRAY_SIZE(pages)), pages);
1275                 if (ret == 0) {
1276                         ret = -EAGAIN;
1277                         goto done;
1278                 }
1279                 /* now we have an array of pages, lock them all */
1280                 for (i = 0; i < ret; i++) {
1281                         /*
1282                          * the caller is taking responsibility for
1283                          * locked_page
1284                          */
1285                         if (pages[i] != locked_page) {
1286                                 lock_page(pages[i]);
1287                                 if (!PageDirty(pages[i]) ||
1288                                     pages[i]->mapping != inode->i_mapping) {
1289                                         ret = -EAGAIN;
1290                                         unlock_page(pages[i]);
1291                                         page_cache_release(pages[i]);
1292                                         goto done;
1293                                 }
1294                         }
1295                         page_cache_release(pages[i]);
1296                         pages_locked++;
1297                 }
1298                 nrpages -= ret;
1299                 index += ret;
1300                 cond_resched();
1301         }
1302         ret = 0;
1303 done:
1304         if (ret && pages_locked) {
1305                 __unlock_for_delalloc(inode, locked_page,
1306                               delalloc_start,
1307                               ((u64)(start_index + pages_locked - 1)) <<
1308                               PAGE_CACHE_SHIFT);
1309         }
1310         return ret;
1311 }
1312
1313 /*
1314  * find a contiguous range of bytes in the file marked as delalloc, not
1315  * more than 'max_bytes'.  start and end are used to return the range,
1316  *
1317  * 1 is returned if we find something, 0 if nothing was in the tree
1318  */
1319 static noinline u64 find_lock_delalloc_range(struct inode *inode,
1320                                              struct extent_io_tree *tree,
1321                                              struct page *locked_page,
1322                                              u64 *start, u64 *end,
1323                                              u64 max_bytes)
1324 {
1325         u64 delalloc_start;
1326         u64 delalloc_end;
1327         u64 found;
1328         struct extent_state *cached_state = NULL;
1329         int ret;
1330         int loops = 0;
1331
1332 again:
1333         /* step one, find a bunch of delalloc bytes starting at start */
1334         delalloc_start = *start;
1335         delalloc_end = 0;
1336         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1337                                     max_bytes);
1338         if (!found || delalloc_end <= *start) {
1339                 *start = delalloc_start;
1340                 *end = delalloc_end;
1341                 return found;
1342         }
1343
1344         /*
1345          * start comes from the offset of locked_page.  We have to lock
1346          * pages in order, so we can't process delalloc bytes before
1347          * locked_page
1348          */
1349         if (delalloc_start < *start)
1350                 delalloc_start = *start;
1351
1352         /*
1353          * make sure to limit the number of pages we try to lock down
1354          * if we're looping.
1355          */
1356         if (delalloc_end + 1 - delalloc_start > max_bytes && loops)
1357                 delalloc_end = delalloc_start + PAGE_CACHE_SIZE - 1;
1358
1359         /* step two, lock all the pages after the page that has start */
1360         ret = lock_delalloc_pages(inode, locked_page,
1361                                   delalloc_start, delalloc_end);
1362         if (ret == -EAGAIN) {
1363                 /* some of the pages are gone, lets avoid looping by
1364                  * shortening the size of the delalloc range we're searching
1365                  */
1366                 free_extent_state(cached_state);
1367                 if (!loops) {
1368                         unsigned long offset = (*start) & (PAGE_CACHE_SIZE - 1);
1369                         max_bytes = PAGE_CACHE_SIZE - offset;
1370                         loops = 1;
1371                         goto again;
1372                 } else {
1373                         found = 0;
1374                         goto out_failed;
1375                 }
1376         }
1377         BUG_ON(ret);
1378
1379         /* step three, lock the state bits for the whole range */
1380         lock_extent_bits(tree, delalloc_start, delalloc_end,
1381                          0, &cached_state, GFP_NOFS);
1382
1383         /* then test to make sure it is all still delalloc */
1384         ret = test_range_bit(tree, delalloc_start, delalloc_end,
1385                              EXTENT_DELALLOC, 1, cached_state);
1386         if (!ret) {
1387                 unlock_extent_cached(tree, delalloc_start, delalloc_end,
1388                                      &cached_state, GFP_NOFS);
1389                 __unlock_for_delalloc(inode, locked_page,
1390                               delalloc_start, delalloc_end);
1391                 cond_resched();
1392                 goto again;
1393         }
1394         free_extent_state(cached_state);
1395         *start = delalloc_start;
1396         *end = delalloc_end;
1397 out_failed:
1398         return found;
1399 }
1400
1401 int extent_clear_unlock_delalloc(struct inode *inode,
1402                                 struct extent_io_tree *tree,
1403                                 u64 start, u64 end, struct page *locked_page,
1404                                 int unlock_pages,
1405                                 int clear_unlock,
1406                                 int clear_delalloc, int clear_dirty,
1407                                 int set_writeback,
1408                                 int end_writeback,
1409                                 int set_private2)
1410 {
1411         int ret;
1412         struct page *pages[16];
1413         unsigned long index = start >> PAGE_CACHE_SHIFT;
1414         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1415         unsigned long nr_pages = end_index - index + 1;
1416         int i;
1417         int clear_bits = 0;
1418
1419         if (clear_unlock)
1420                 clear_bits |= EXTENT_LOCKED;
1421         if (clear_dirty)
1422                 clear_bits |= EXTENT_DIRTY;
1423
1424         if (clear_delalloc)
1425                 clear_bits |= EXTENT_DELALLOC;
1426
1427         clear_extent_bit(tree, start, end, clear_bits, 1, 0, NULL, GFP_NOFS);
1428         if (!(unlock_pages || clear_dirty || set_writeback || end_writeback ||
1429               set_private2))
1430                 return 0;
1431
1432         while (nr_pages > 0) {
1433                 ret = find_get_pages_contig(inode->i_mapping, index,
1434                                      min_t(unsigned long,
1435                                      nr_pages, ARRAY_SIZE(pages)), pages);
1436                 for (i = 0; i < ret; i++) {
1437
1438                         if (set_private2)
1439                                 SetPagePrivate2(pages[i]);
1440
1441                         if (pages[i] == locked_page) {
1442                                 page_cache_release(pages[i]);
1443                                 continue;
1444                         }
1445                         if (clear_dirty)
1446                                 clear_page_dirty_for_io(pages[i]);
1447                         if (set_writeback)
1448                                 set_page_writeback(pages[i]);
1449                         if (end_writeback)
1450                                 end_page_writeback(pages[i]);
1451                         if (unlock_pages)
1452                                 unlock_page(pages[i]);
1453                         page_cache_release(pages[i]);
1454                 }
1455                 nr_pages -= ret;
1456                 index += ret;
1457                 cond_resched();
1458         }
1459         return 0;
1460 }
1461
1462 /*
1463  * count the number of bytes in the tree that have a given bit(s)
1464  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1465  * cached.  The total number found is returned.
1466  */
1467 u64 count_range_bits(struct extent_io_tree *tree,
1468                      u64 *start, u64 search_end, u64 max_bytes,
1469                      unsigned long bits)
1470 {
1471         struct rb_node *node;
1472         struct extent_state *state;
1473         u64 cur_start = *start;
1474         u64 total_bytes = 0;
1475         int found = 0;
1476
1477         if (search_end <= cur_start) {
1478                 WARN_ON(1);
1479                 return 0;
1480         }
1481
1482         spin_lock(&tree->lock);
1483         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1484                 total_bytes = tree->dirty_bytes;
1485                 goto out;
1486         }
1487         /*
1488          * this search will find all the extents that end after
1489          * our range starts.
1490          */
1491         node = tree_search(tree, cur_start);
1492         if (!node)
1493                 goto out;
1494
1495         while (1) {
1496                 state = rb_entry(node, struct extent_state, rb_node);
1497                 if (state->start > search_end)
1498                         break;
1499                 if (state->end >= cur_start && (state->state & bits)) {
1500                         total_bytes += min(search_end, state->end) + 1 -
1501                                        max(cur_start, state->start);
1502                         if (total_bytes >= max_bytes)
1503                                 break;
1504                         if (!found) {
1505                                 *start = state->start;
1506                                 found = 1;
1507                         }
1508                 }
1509                 node = rb_next(node);
1510                 if (!node)
1511                         break;
1512         }
1513 out:
1514         spin_unlock(&tree->lock);
1515         return total_bytes;
1516 }
1517
1518 /*
1519  * set the private field for a given byte offset in the tree.  If there isn't
1520  * an extent_state there already, this does nothing.
1521  */
1522 int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
1523 {
1524         struct rb_node *node;
1525         struct extent_state *state;
1526         int ret = 0;
1527
1528         spin_lock(&tree->lock);
1529         /*
1530          * this search will find all the extents that end after
1531          * our range starts.
1532          */
1533         node = tree_search(tree, start);
1534         if (!node) {
1535                 ret = -ENOENT;
1536                 goto out;
1537         }
1538         state = rb_entry(node, struct extent_state, rb_node);
1539         if (state->start != start) {
1540                 ret = -ENOENT;
1541                 goto out;
1542         }
1543         state->private = private;
1544 out:
1545         spin_unlock(&tree->lock);
1546         return ret;
1547 }
1548
1549 int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
1550 {
1551         struct rb_node *node;
1552         struct extent_state *state;
1553         int ret = 0;
1554
1555         spin_lock(&tree->lock);
1556         /*
1557          * this search will find all the extents that end after
1558          * our range starts.
1559          */
1560         node = tree_search(tree, start);
1561         if (!node) {
1562                 ret = -ENOENT;
1563                 goto out;
1564         }
1565         state = rb_entry(node, struct extent_state, rb_node);
1566         if (state->start != start) {
1567                 ret = -ENOENT;
1568                 goto out;
1569         }
1570         *private = state->private;
1571 out:
1572         spin_unlock(&tree->lock);
1573         return ret;
1574 }
1575
1576 /*
1577  * searches a range in the state tree for a given mask.
1578  * If 'filled' == 1, this returns 1 only if every extent in the tree
1579  * has the bits set.  Otherwise, 1 is returned if any bit in the
1580  * range is found set.
1581  */
1582 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
1583                    int bits, int filled, struct extent_state *cached)
1584 {
1585         struct extent_state *state = NULL;
1586         struct rb_node *node;
1587         int bitset = 0;
1588
1589         spin_lock(&tree->lock);
1590         if (cached && cached->tree && cached->start == start)
1591                 node = &cached->rb_node;
1592         else
1593                 node = tree_search(tree, start);
1594         while (node && start <= end) {
1595                 state = rb_entry(node, struct extent_state, rb_node);
1596
1597                 if (filled && state->start > start) {
1598                         bitset = 0;
1599                         break;
1600                 }
1601
1602                 if (state->start > end)
1603                         break;
1604
1605                 if (state->state & bits) {
1606                         bitset = 1;
1607                         if (!filled)
1608                                 break;
1609                 } else if (filled) {
1610                         bitset = 0;
1611                         break;
1612                 }
1613
1614                 if (state->end == (u64)-1)
1615                         break;
1616
1617                 start = state->end + 1;
1618                 if (start > end)
1619                         break;
1620                 node = rb_next(node);
1621                 if (!node) {
1622                         if (filled)
1623                                 bitset = 0;
1624                         break;
1625                 }
1626         }
1627         spin_unlock(&tree->lock);
1628         return bitset;
1629 }
1630
1631 /*
1632  * helper function to set a given page up to date if all the
1633  * extents in the tree for that page are up to date
1634  */
1635 static int check_page_uptodate(struct extent_io_tree *tree,
1636                                struct page *page)
1637 {
1638         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1639         u64 end = start + PAGE_CACHE_SIZE - 1;
1640         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
1641                 SetPageUptodate(page);
1642         return 0;
1643 }
1644
1645 /*
1646  * helper function to unlock a page if all the extents in the tree
1647  * for that page are unlocked
1648  */
1649 static int check_page_locked(struct extent_io_tree *tree,
1650                              struct page *page)
1651 {
1652         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1653         u64 end = start + PAGE_CACHE_SIZE - 1;
1654         if (!test_range_bit(tree, start, end, EXTENT_LOCKED, 0, NULL))
1655                 unlock_page(page);
1656         return 0;
1657 }
1658
1659 /*
1660  * helper function to end page writeback if all the extents
1661  * in the tree for that page are done with writeback
1662  */
1663 static int check_page_writeback(struct extent_io_tree *tree,
1664                              struct page *page)
1665 {
1666         end_page_writeback(page);
1667         return 0;
1668 }
1669
1670 /* lots and lots of room for performance fixes in the end_bio funcs */
1671
1672 /*
1673  * after a writepage IO is done, we need to:
1674  * clear the uptodate bits on error
1675  * clear the writeback bits in the extent tree for this IO
1676  * end_page_writeback if the page has no more pending IO
1677  *
1678  * Scheduling is not allowed, so the extent state tree is expected
1679  * to have one and only one object corresponding to this IO.
1680  */
1681 static void end_bio_extent_writepage(struct bio *bio, int err)
1682 {
1683         int uptodate = err == 0;
1684         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1685         struct extent_io_tree *tree;
1686         u64 start;
1687         u64 end;
1688         int whole_page;
1689         int ret;
1690
1691         do {
1692                 struct page *page = bvec->bv_page;
1693                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1694
1695                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1696                          bvec->bv_offset;
1697                 end = start + bvec->bv_len - 1;
1698
1699                 if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
1700                         whole_page = 1;
1701                 else
1702                         whole_page = 0;
1703
1704                 if (--bvec >= bio->bi_io_vec)
1705                         prefetchw(&bvec->bv_page->flags);
1706                 if (tree->ops && tree->ops->writepage_end_io_hook) {
1707                         ret = tree->ops->writepage_end_io_hook(page, start,
1708                                                        end, NULL, uptodate);
1709                         if (ret)
1710                                 uptodate = 0;
1711                 }
1712
1713                 if (!uptodate && tree->ops &&
1714                     tree->ops->writepage_io_failed_hook) {
1715                         ret = tree->ops->writepage_io_failed_hook(bio, page,
1716                                                          start, end, NULL);
1717                         if (ret == 0) {
1718                                 uptodate = (err == 0);
1719                                 continue;
1720                         }
1721                 }
1722
1723                 if (!uptodate) {
1724                         clear_extent_uptodate(tree, start, end, GFP_NOFS);
1725                         ClearPageUptodate(page);
1726                         SetPageError(page);
1727                 }
1728
1729                 if (whole_page)
1730                         end_page_writeback(page);
1731                 else
1732                         check_page_writeback(tree, page);
1733         } while (bvec >= bio->bi_io_vec);
1734
1735         bio_put(bio);
1736 }
1737
1738 /*
1739  * after a readpage IO is done, we need to:
1740  * clear the uptodate bits on error
1741  * set the uptodate bits if things worked
1742  * set the page up to date if all extents in the tree are uptodate
1743  * clear the lock bit in the extent tree
1744  * unlock the page if there are no other extents locked for it
1745  *
1746  * Scheduling is not allowed, so the extent state tree is expected
1747  * to have one and only one object corresponding to this IO.
1748  */
1749 static void end_bio_extent_readpage(struct bio *bio, int err)
1750 {
1751         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1752         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1753         struct extent_io_tree *tree;
1754         u64 start;
1755         u64 end;
1756         int whole_page;
1757         int ret;
1758
1759         if (err)
1760                 uptodate = 0;
1761
1762         do {
1763                 struct page *page = bvec->bv_page;
1764                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1765
1766                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1767                         bvec->bv_offset;
1768                 end = start + bvec->bv_len - 1;
1769
1770                 if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
1771                         whole_page = 1;
1772                 else
1773                         whole_page = 0;
1774
1775                 if (--bvec >= bio->bi_io_vec)
1776                         prefetchw(&bvec->bv_page->flags);
1777
1778                 if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
1779                         ret = tree->ops->readpage_end_io_hook(page, start, end,
1780                                                               NULL);
1781                         if (ret)
1782                                 uptodate = 0;
1783                 }
1784                 if (!uptodate && tree->ops &&
1785                     tree->ops->readpage_io_failed_hook) {
1786                         ret = tree->ops->readpage_io_failed_hook(bio, page,
1787                                                          start, end, NULL);
1788                         if (ret == 0) {
1789                                 uptodate =
1790                                         test_bit(BIO_UPTODATE, &bio->bi_flags);
1791                                 if (err)
1792                                         uptodate = 0;
1793                                 continue;
1794                         }
1795                 }
1796
1797                 if (uptodate) {
1798                         set_extent_uptodate(tree, start, end,
1799                                             GFP_ATOMIC);
1800                 }
1801                 unlock_extent(tree, start, end, GFP_ATOMIC);
1802
1803                 if (whole_page) {
1804                         if (uptodate) {
1805                                 SetPageUptodate(page);
1806                         } else {
1807                                 ClearPageUptodate(page);
1808                                 SetPageError(page);
1809                         }
1810                         unlock_page(page);
1811                 } else {
1812                         if (uptodate) {
1813                                 check_page_uptodate(tree, page);
1814                         } else {
1815                                 ClearPageUptodate(page);
1816                                 SetPageError(page);
1817                         }
1818                         check_page_locked(tree, page);
1819                 }
1820         } while (bvec >= bio->bi_io_vec);
1821
1822         bio_put(bio);
1823 }
1824
1825 /*
1826  * IO done from prepare_write is pretty simple, we just unlock
1827  * the structs in the extent tree when done, and set the uptodate bits
1828  * as appropriate.
1829  */
1830 static void end_bio_extent_preparewrite(struct bio *bio, int err)
1831 {
1832         const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1833         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1834         struct extent_io_tree *tree;
1835         u64 start;
1836         u64 end;
1837
1838         do {
1839                 struct page *page = bvec->bv_page;
1840                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1841
1842                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1843                         bvec->bv_offset;
1844                 end = start + bvec->bv_len - 1;
1845
1846                 if (--bvec >= bio->bi_io_vec)
1847                         prefetchw(&bvec->bv_page->flags);
1848
1849                 if (uptodate) {
1850                         set_extent_uptodate(tree, start, end, GFP_ATOMIC);
1851                 } else {
1852                         ClearPageUptodate(page);
1853                         SetPageError(page);
1854                 }
1855
1856                 unlock_extent(tree, start, end, GFP_ATOMIC);
1857
1858         } while (bvec >= bio->bi_io_vec);
1859
1860         bio_put(bio);
1861 }
1862
1863 static struct bio *
1864 extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
1865                  gfp_t gfp_flags)
1866 {
1867         struct bio *bio;
1868
1869         bio = bio_alloc(gfp_flags, nr_vecs);
1870
1871         if (bio == NULL && (current->flags & PF_MEMALLOC)) {
1872                 while (!bio && (nr_vecs /= 2))
1873                         bio = bio_alloc(gfp_flags, nr_vecs);
1874         }
1875
1876         if (bio) {
1877                 bio->bi_size = 0;
1878                 bio->bi_bdev = bdev;
1879                 bio->bi_sector = first_sector;
1880         }
1881         return bio;
1882 }
1883
1884 static int submit_one_bio(int rw, struct bio *bio, int mirror_num,
1885                           unsigned long bio_flags)
1886 {
1887         int ret = 0;
1888         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1889         struct page *page = bvec->bv_page;
1890         struct extent_io_tree *tree = bio->bi_private;
1891         u64 start;
1892         u64 end;
1893
1894         start = ((u64)page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset;
1895         end = start + bvec->bv_len - 1;
1896
1897         bio->bi_private = NULL;
1898
1899         bio_get(bio);
1900
1901         if (tree->ops && tree->ops->submit_bio_hook)
1902                 tree->ops->submit_bio_hook(page->mapping->host, rw, bio,
1903                                            mirror_num, bio_flags);
1904         else
1905                 submit_bio(rw, bio);
1906         if (bio_flagged(bio, BIO_EOPNOTSUPP))
1907                 ret = -EOPNOTSUPP;
1908         bio_put(bio);
1909         return ret;
1910 }
1911
1912 static int submit_extent_page(int rw, struct extent_io_tree *tree,
1913                               struct page *page, sector_t sector,
1914                               size_t size, unsigned long offset,
1915                               struct block_device *bdev,
1916                               struct bio **bio_ret,
1917                               unsigned long max_pages,
1918                               bio_end_io_t end_io_func,
1919                               int mirror_num,
1920                               unsigned long prev_bio_flags,
1921                               unsigned long bio_flags)
1922 {
1923         int ret = 0;
1924         struct bio *bio;
1925         int nr;
1926         int contig = 0;
1927         int this_compressed = bio_flags & EXTENT_BIO_COMPRESSED;
1928         int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
1929         size_t page_size = min_t(size_t, size, PAGE_CACHE_SIZE);
1930
1931         if (bio_ret && *bio_ret) {
1932                 bio = *bio_ret;
1933                 if (old_compressed)
1934                         contig = bio->bi_sector == sector;
1935                 else
1936                         contig = bio->bi_sector + (bio->bi_size >> 9) ==
1937                                 sector;
1938
1939                 if (prev_bio_flags != bio_flags || !contig ||
1940                     (tree->ops && tree->ops->merge_bio_hook &&
1941                      tree->ops->merge_bio_hook(page, offset, page_size, bio,
1942                                                bio_flags)) ||
1943                     bio_add_page(bio, page, page_size, offset) < page_size) {
1944                         ret = submit_one_bio(rw, bio, mirror_num,
1945                                              prev_bio_flags);
1946                         bio = NULL;
1947                 } else {
1948                         return 0;
1949                 }
1950         }
1951         if (this_compressed)
1952                 nr = BIO_MAX_PAGES;
1953         else
1954                 nr = bio_get_nr_vecs(bdev);
1955
1956         bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
1957
1958         bio_add_page(bio, page, page_size, offset);
1959         bio->bi_end_io = end_io_func;
1960         bio->bi_private = tree;
1961
1962         if (bio_ret)
1963                 *bio_ret = bio;
1964         else
1965                 ret = submit_one_bio(rw, bio, mirror_num, bio_flags);
1966
1967         return ret;
1968 }
1969
1970 void set_page_extent_mapped(struct page *page)
1971 {
1972         if (!PagePrivate(page)) {
1973                 SetPagePrivate(page);
1974                 page_cache_get(page);
1975                 set_page_private(page, EXTENT_PAGE_PRIVATE);
1976         }
1977 }
1978
1979 static void set_page_extent_head(struct page *page, unsigned long len)
1980 {
1981         set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2);
1982 }
1983
1984 /*
1985  * basic readpage implementation.  Locked extent state structs are inserted
1986  * into the tree that are removed when the IO is done (by the end_io
1987  * handlers)
1988  */
1989 static int __extent_read_full_page(struct extent_io_tree *tree,
1990                                    struct page *page,
1991                                    get_extent_t *get_extent,
1992                                    struct bio **bio, int mirror_num,
1993                                    unsigned long *bio_flags)
1994 {
1995         struct inode *inode = page->mapping->host;
1996         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1997         u64 page_end = start + PAGE_CACHE_SIZE - 1;
1998         u64 end;
1999         u64 cur = start;
2000         u64 extent_offset;
2001         u64 last_byte = i_size_read(inode);
2002         u64 block_start;
2003         u64 cur_end;
2004         sector_t sector;
2005         struct extent_map *em;
2006         struct block_device *bdev;
2007         int ret;
2008         int nr = 0;
2009         size_t page_offset = 0;
2010         size_t iosize;
2011         size_t disk_io_size;
2012         size_t blocksize = inode->i_sb->s_blocksize;
2013         unsigned long this_bio_flag = 0;
2014
2015         set_page_extent_mapped(page);
2016
2017         end = page_end;
2018         lock_extent(tree, start, end, GFP_NOFS);
2019
2020         if (page->index == last_byte >> PAGE_CACHE_SHIFT) {
2021                 char *userpage;
2022                 size_t zero_offset = last_byte & (PAGE_CACHE_SIZE - 1);
2023
2024                 if (zero_offset) {
2025                         iosize = PAGE_CACHE_SIZE - zero_offset;
2026                         userpage = kmap_atomic(page, KM_USER0);
2027                         memset(userpage + zero_offset, 0, iosize);
2028                         flush_dcache_page(page);
2029                         kunmap_atomic(userpage, KM_USER0);
2030                 }
2031         }
2032         while (cur <= end) {
2033                 if (cur >= last_byte) {
2034                         char *userpage;
2035                         iosize = PAGE_CACHE_SIZE - page_offset;
2036                         userpage = kmap_atomic(page, KM_USER0);
2037                         memset(userpage + page_offset, 0, iosize);
2038                         flush_dcache_page(page);
2039                         kunmap_atomic(userpage, KM_USER0);
2040                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2041                                             GFP_NOFS);
2042                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2043                         break;
2044                 }
2045                 em = get_extent(inode, page, page_offset, cur,
2046                                 end - cur + 1, 0);
2047                 if (IS_ERR(em) || !em) {
2048                         SetPageError(page);
2049                         unlock_extent(tree, cur, end, GFP_NOFS);
2050                         break;
2051                 }
2052                 extent_offset = cur - em->start;
2053                 BUG_ON(extent_map_end(em) <= cur);
2054                 BUG_ON(end < cur);
2055
2056                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
2057                         this_bio_flag = EXTENT_BIO_COMPRESSED;
2058
2059                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2060                 cur_end = min(extent_map_end(em) - 1, end);
2061                 iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
2062                 if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
2063                         disk_io_size = em->block_len;
2064                         sector = em->block_start >> 9;
2065                 } else {
2066                         sector = (em->block_start + extent_offset) >> 9;
2067                         disk_io_size = iosize;
2068                 }
2069                 bdev = em->bdev;
2070                 block_start = em->block_start;
2071                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
2072                         block_start = EXTENT_MAP_HOLE;
2073                 free_extent_map(em);
2074                 em = NULL;
2075
2076                 /* we've found a hole, just zero and go on */
2077                 if (block_start == EXTENT_MAP_HOLE) {
2078                         char *userpage;
2079                         userpage = kmap_atomic(page, KM_USER0);
2080                         memset(userpage + page_offset, 0, iosize);
2081                         flush_dcache_page(page);
2082                         kunmap_atomic(userpage, KM_USER0);
2083
2084                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2085                                             GFP_NOFS);
2086                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2087                         cur = cur + iosize;
2088                         page_offset += iosize;
2089                         continue;
2090                 }
2091                 /* the get_extent function already copied into the page */
2092                 if (test_range_bit(tree, cur, cur_end,
2093                                    EXTENT_UPTODATE, 1, NULL)) {
2094                         check_page_uptodate(tree, page);
2095                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2096                         cur = cur + iosize;
2097                         page_offset += iosize;
2098                         continue;
2099                 }
2100                 /* we have an inline extent but it didn't get marked up
2101                  * to date.  Error out
2102                  */
2103                 if (block_start == EXTENT_MAP_INLINE) {
2104                         SetPageError(page);
2105                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2106                         cur = cur + iosize;
2107                         page_offset += iosize;
2108                         continue;
2109                 }
2110
2111                 ret = 0;
2112                 if (tree->ops && tree->ops->readpage_io_hook) {
2113                         ret = tree->ops->readpage_io_hook(page, cur,
2114                                                           cur + iosize - 1);
2115                 }
2116                 if (!ret) {
2117                         unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
2118                         pnr -= page->index;
2119                         ret = submit_extent_page(READ, tree, page,
2120                                          sector, disk_io_size, page_offset,
2121                                          bdev, bio, pnr,
2122                                          end_bio_extent_readpage, mirror_num,
2123                                          *bio_flags,
2124                                          this_bio_flag);
2125                         nr++;
2126                         *bio_flags = this_bio_flag;
2127                 }
2128                 if (ret)
2129                         SetPageError(page);
2130                 cur = cur + iosize;
2131                 page_offset += iosize;
2132         }
2133         if (!nr) {
2134                 if (!PageError(page))
2135                         SetPageUptodate(page);
2136                 unlock_page(page);
2137         }
2138         return 0;
2139 }
2140
2141 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
2142                             get_extent_t *get_extent)
2143 {
2144         struct bio *bio = NULL;
2145         unsigned long bio_flags = 0;
2146         int ret;
2147
2148         ret = __extent_read_full_page(tree, page, get_extent, &bio, 0,
2149                                       &bio_flags);
2150         if (bio)
2151                 submit_one_bio(READ, bio, 0, bio_flags);
2152         return ret;
2153 }
2154
2155 static noinline void update_nr_written(struct page *page,
2156                                       struct writeback_control *wbc,
2157                                       unsigned long nr_written)
2158 {
2159         wbc->nr_to_write -= nr_written;
2160         if (wbc->range_cyclic || (wbc->nr_to_write > 0 &&
2161             wbc->range_start == 0 && wbc->range_end == LLONG_MAX))
2162                 page->mapping->writeback_index = page->index + nr_written;
2163 }
2164
2165 /*
2166  * the writepage semantics are similar to regular writepage.  extent
2167  * records are inserted to lock ranges in the tree, and as dirty areas
2168  * are found, they are marked writeback.  Then the lock bits are removed
2169  * and the end_io handler clears the writeback ranges
2170  */
2171 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
2172                               void *data)
2173 {
2174         struct inode *inode = page->mapping->host;
2175         struct extent_page_data *epd = data;
2176         struct extent_io_tree *tree = epd->tree;
2177         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2178         u64 delalloc_start;
2179         u64 page_end = start + PAGE_CACHE_SIZE - 1;
2180         u64 end;
2181         u64 cur = start;
2182         u64 extent_offset;
2183         u64 last_byte = i_size_read(inode);
2184         u64 block_start;
2185         u64 iosize;
2186         u64 unlock_start;
2187         sector_t sector;
2188         struct extent_state *cached_state = NULL;
2189         struct extent_map *em;
2190         struct block_device *bdev;
2191         int ret;
2192         int nr = 0;
2193         size_t pg_offset = 0;
2194         size_t blocksize;
2195         loff_t i_size = i_size_read(inode);
2196         unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
2197         u64 nr_delalloc;
2198         u64 delalloc_end;
2199         int page_started;
2200         int compressed;
2201         int write_flags;
2202         unsigned long nr_written = 0;
2203
2204         if (wbc->sync_mode == WB_SYNC_ALL)
2205                 write_flags = WRITE_SYNC_PLUG;
2206         else
2207                 write_flags = WRITE;
2208
2209         WARN_ON(!PageLocked(page));
2210         pg_offset = i_size & (PAGE_CACHE_SIZE - 1);
2211         if (page->index > end_index ||
2212            (page->index == end_index && !pg_offset)) {
2213                 page->mapping->a_ops->invalidatepage(page, 0);
2214                 unlock_page(page);
2215                 return 0;
2216         }
2217
2218         if (page->index == end_index) {
2219                 char *userpage;
2220
2221                 userpage = kmap_atomic(page, KM_USER0);
2222                 memset(userpage + pg_offset, 0,
2223                        PAGE_CACHE_SIZE - pg_offset);
2224                 kunmap_atomic(userpage, KM_USER0);
2225                 flush_dcache_page(page);
2226         }
2227         pg_offset = 0;
2228
2229         set_page_extent_mapped(page);
2230
2231         delalloc_start = start;
2232         delalloc_end = 0;
2233         page_started = 0;
2234         if (!epd->extent_locked) {
2235                 u64 delalloc_to_write = 0;
2236                 /*
2237                  * make sure the wbc mapping index is at least updated
2238                  * to this page.
2239                  */
2240                 update_nr_written(page, wbc, 0);
2241
2242                 while (delalloc_end < page_end) {
2243                         nr_delalloc = find_lock_delalloc_range(inode, tree,
2244                                                        page,
2245                                                        &delalloc_start,
2246                                                        &delalloc_end,
2247                                                        128 * 1024 * 1024);
2248                         if (nr_delalloc == 0) {
2249                                 delalloc_start = delalloc_end + 1;
2250                                 continue;
2251                         }
2252                         tree->ops->fill_delalloc(inode, page, delalloc_start,
2253                                                  delalloc_end, &page_started,
2254                                                  &nr_written);
2255                         /*
2256                          * delalloc_end is already one less than the total
2257                          * length, so we don't subtract one from
2258                          * PAGE_CACHE_SIZE
2259                          */
2260                         delalloc_to_write += (delalloc_end - delalloc_start +
2261                                               PAGE_CACHE_SIZE) >>
2262                                               PAGE_CACHE_SHIFT;
2263                         delalloc_start = delalloc_end + 1;
2264                 }
2265                 if (wbc->nr_to_write < delalloc_to_write) {
2266                         int thresh = 8192;
2267
2268                         if (delalloc_to_write < thresh * 2)
2269                                 thresh = delalloc_to_write;
2270                         wbc->nr_to_write = min_t(u64, delalloc_to_write,
2271                                                  thresh);
2272                 }
2273
2274                 /* did the fill delalloc function already unlock and start
2275                  * the IO?
2276                  */
2277                 if (page_started) {
2278                         ret = 0;
2279                         /*
2280                          * we've unlocked the page, so we can't update
2281                          * the mapping's writeback index, just update
2282                          * nr_to_write.
2283                          */
2284                         wbc->nr_to_write -= nr_written;
2285                         goto done_unlocked;
2286                 }
2287         }
2288         if (tree->ops && tree->ops->writepage_start_hook) {
2289                 ret = tree->ops->writepage_start_hook(page, start,
2290                                                       page_end);
2291                 if (ret == -EAGAIN) {
2292                         redirty_page_for_writepage(wbc, page);
2293                         update_nr_written(page, wbc, nr_written);
2294                         unlock_page(page);
2295                         ret = 0;
2296                         goto done_unlocked;
2297                 }
2298         }
2299
2300         /*
2301          * we don't want to touch the inode after unlocking the page,
2302          * so we update the mapping writeback index now
2303          */
2304         update_nr_written(page, wbc, nr_written + 1);
2305
2306         end = page_end;
2307         if (last_byte <= start) {
2308                 if (tree->ops && tree->ops->writepage_end_io_hook)
2309                         tree->ops->writepage_end_io_hook(page, start,
2310                                                          page_end, NULL, 1);
2311                 unlock_start = page_end + 1;
2312                 goto done;
2313         }
2314
2315         blocksize = inode->i_sb->s_blocksize;
2316
2317         while (cur <= end) {
2318                 if (cur >= last_byte) {
2319                         if (tree->ops && tree->ops->writepage_end_io_hook)
2320                                 tree->ops->writepage_end_io_hook(page, cur,
2321                                                          page_end, NULL, 1);
2322                         unlock_start = page_end + 1;
2323                         break;
2324                 }
2325                 em = epd->get_extent(inode, page, pg_offset, cur,
2326                                      end - cur + 1, 1);
2327                 if (IS_ERR(em) || !em) {
2328                         SetPageError(page);
2329                         break;
2330                 }
2331
2332                 extent_offset = cur - em->start;
2333                 BUG_ON(extent_map_end(em) <= cur);
2334                 BUG_ON(end < cur);
2335                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2336                 iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
2337                 sector = (em->block_start + extent_offset) >> 9;
2338                 bdev = em->bdev;
2339                 block_start = em->block_start;
2340                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
2341                 free_extent_map(em);
2342                 em = NULL;
2343
2344                 /*
2345                  * compressed and inline extents are written through other
2346                  * paths in the FS
2347                  */
2348                 if (compressed || block_start == EXTENT_MAP_HOLE ||
2349                     block_start == EXTENT_MAP_INLINE) {
2350                         /*
2351                          * end_io notification does not happen here for
2352                          * compressed extents
2353                          */
2354                         if (!compressed && tree->ops &&
2355                             tree->ops->writepage_end_io_hook)
2356                                 tree->ops->writepage_end_io_hook(page, cur,
2357                                                          cur + iosize - 1,
2358                                                          NULL, 1);
2359                         else if (compressed) {
2360                                 /* we don't want to end_page_writeback on
2361                                  * a compressed extent.  this happens
2362                                  * elsewhere
2363                                  */
2364                                 nr++;
2365                         }
2366
2367                         cur += iosize;
2368                         pg_offset += iosize;
2369                         unlock_start = cur;
2370                         continue;
2371                 }
2372                 /* leave this out until we have a page_mkwrite call */
2373                 if (0 && !test_range_bit(tree, cur, cur + iosize - 1,
2374                                    EXTENT_DIRTY, 0, NULL)) {
2375                         cur = cur + iosize;
2376                         pg_offset += iosize;
2377                         continue;
2378                 }
2379
2380                 if (tree->ops && tree->ops->writepage_io_hook) {
2381                         ret = tree->ops->writepage_io_hook(page, cur,
2382                                                 cur + iosize - 1);
2383                 } else {
2384                         ret = 0;
2385                 }
2386                 if (ret) {
2387                         SetPageError(page);
2388                 } else {
2389                         unsigned long max_nr = end_index + 1;
2390
2391                         set_range_writeback(tree, cur, cur + iosize - 1);
2392                         if (!PageWriteback(page)) {
2393                                 printk(KERN_ERR "btrfs warning page %lu not "
2394                                        "writeback, cur %llu end %llu\n",
2395                                        page->index, (unsigned long long)cur,
2396                                        (unsigned long long)end);
2397                         }
2398
2399                         ret = submit_extent_page(write_flags, tree, page,
2400                                                  sector, iosize, pg_offset,
2401                                                  bdev, &epd->bio, max_nr,
2402                                                  end_bio_extent_writepage,
2403                                                  0, 0, 0);
2404                         if (ret)
2405                                 SetPageError(page);
2406                 }
2407                 cur = cur + iosize;
2408                 pg_offset += iosize;
2409                 nr++;
2410         }
2411 done:
2412         if (nr == 0) {
2413                 /* make sure the mapping tag for page dirty gets cleared */
2414                 set_page_writeback(page);
2415                 end_page_writeback(page);
2416         }
2417         unlock_page(page);
2418
2419 done_unlocked:
2420
2421         /* drop our reference on any cached states */
2422         free_extent_state(cached_state);
2423         return 0;
2424 }
2425
2426 /**
2427  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
2428  * @mapping: address space structure to write
2429  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
2430  * @writepage: function called for each page
2431  * @data: data passed to writepage function
2432  *
2433  * If a page is already under I/O, write_cache_pages() skips it, even
2434  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
2435  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
2436  * and msync() need to guarantee that all the data which was dirty at the time
2437  * the call was made get new I/O started against them.  If wbc->sync_mode is
2438  * WB_SYNC_ALL then we were called for data integrity and we must wait for
2439  * existing IO to complete.
2440  */
2441 static int extent_write_cache_pages(struct extent_io_tree *tree,
2442                              struct address_space *mapping,
2443                              struct writeback_control *wbc,
2444                              writepage_t writepage, void *data,
2445                              void (*flush_fn)(void *))
2446 {
2447         int ret = 0;
2448         int done = 0;
2449         int nr_to_write_done = 0;
2450         struct pagevec pvec;
2451         int nr_pages;
2452         pgoff_t index;
2453         pgoff_t end;            /* Inclusive */
2454         int scanned = 0;
2455         int range_whole = 0;
2456
2457         pagevec_init(&pvec, 0);
2458         if (wbc->range_cyclic) {
2459                 index = mapping->writeback_index; /* Start from prev offset */
2460                 end = -1;
2461         } else {
2462                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2463                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
2464                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2465                         range_whole = 1;
2466                 scanned = 1;
2467         }
2468 retry:
2469         while (!done && !nr_to_write_done && (index <= end) &&
2470                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
2471                               PAGECACHE_TAG_DIRTY, min(end - index,
2472                                   (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
2473                 unsigned i;
2474
2475                 scanned = 1;
2476                 for (i = 0; i < nr_pages; i++) {
2477                         struct page *page = pvec.pages[i];
2478
2479                         /*
2480                          * At this point we hold neither mapping->tree_lock nor
2481                          * lock on the page itself: the page may be truncated or
2482                          * invalidated (changing page->mapping to NULL), or even
2483                          * swizzled back from swapper_space to tmpfs file
2484                          * mapping
2485                          */
2486                         if (tree->ops && tree->ops->write_cache_pages_lock_hook)
2487                                 tree->ops->write_cache_pages_lock_hook(page);
2488                         else
2489                                 lock_page(page);
2490
2491                         if (unlikely(page->mapping != mapping)) {
2492                                 unlock_page(page);
2493                                 continue;
2494                         }
2495
2496                         if (!wbc->range_cyclic && page->index > end) {
2497                                 done = 1;
2498                                 unlock_page(page);
2499                                 continue;
2500                         }
2501
2502                         if (wbc->sync_mode != WB_SYNC_NONE) {
2503                                 if (PageWriteback(page))
2504                                         flush_fn(data);
2505                                 wait_on_page_writeback(page);
2506                         }
2507
2508                         if (PageWriteback(page) ||
2509                             !clear_page_dirty_for_io(page)) {
2510                                 unlock_page(page);
2511                                 continue;
2512                         }
2513
2514                         ret = (*writepage)(page, wbc, data);
2515
2516                         if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
2517                                 unlock_page(page);
2518                                 ret = 0;
2519                         }
2520                         if (ret)
2521                                 done = 1;
2522
2523                         /*
2524                          * the filesystem may choose to bump up nr_to_write.
2525                          * We have to make sure to honor the new nr_to_write
2526                          * at any time
2527                          */
2528                         nr_to_write_done = wbc->nr_to_write <= 0;
2529                 }
2530                 pagevec_release(&pvec);
2531                 cond_resched();
2532         }
2533         if (!scanned && !done) {
2534                 /*
2535                  * We hit the last page and there is more work to be done: wrap
2536                  * back to the start of the file
2537                  */
2538                 scanned = 1;
2539                 index = 0;
2540                 goto retry;
2541         }
2542         return ret;
2543 }
2544
2545 static void flush_epd_write_bio(struct extent_page_data *epd)
2546 {
2547         if (epd->bio) {
2548                 if (epd->sync_io)
2549                         submit_one_bio(WRITE_SYNC, epd->bio, 0, 0);
2550                 else
2551                         submit_one_bio(WRITE, epd->bio, 0, 0);
2552                 epd->bio = NULL;
2553         }
2554 }
2555
2556 static noinline void flush_write_bio(void *data)
2557 {
2558         struct extent_page_data *epd = data;
2559         flush_epd_write_bio(epd);
2560 }
2561
2562 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
2563                           get_extent_t *get_extent,
2564                           struct writeback_control *wbc)
2565 {
2566         int ret;
2567         struct address_space *mapping = page->mapping;
2568         struct extent_page_data epd = {
2569                 .bio = NULL,
2570                 .tree = tree,
2571                 .get_extent = get_extent,
2572                 .extent_locked = 0,
2573                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
2574         };
2575         struct writeback_control wbc_writepages = {
2576                 .bdi            = wbc->bdi,
2577                 .sync_mode      = wbc->sync_mode,
2578                 .older_than_this = NULL,
2579                 .nr_to_write    = 64,
2580                 .range_start    = page_offset(page) + PAGE_CACHE_SIZE,
2581                 .range_end      = (loff_t)-1,
2582         };
2583
2584         ret = __extent_writepage(page, wbc, &epd);
2585
2586         extent_write_cache_pages(tree, mapping, &wbc_writepages,
2587                                  __extent_writepage, &epd, flush_write_bio);
2588         flush_epd_write_bio(&epd);
2589         return ret;
2590 }
2591
2592 int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
2593                               u64 start, u64 end, get_extent_t *get_extent,
2594                               int mode)
2595 {
2596         int ret = 0;
2597         struct address_space *mapping = inode->i_mapping;
2598         struct page *page;
2599         unsigned long nr_pages = (end - start + PAGE_CACHE_SIZE) >>
2600                 PAGE_CACHE_SHIFT;
2601
2602         struct extent_page_data epd = {
2603                 .bio = NULL,
2604                 .tree = tree,
2605                 .get_extent = get_extent,
2606                 .extent_locked = 1,
2607                 .sync_io = mode == WB_SYNC_ALL,
2608         };
2609         struct writeback_control wbc_writepages = {
2610                 .bdi            = inode->i_mapping->backing_dev_info,
2611                 .sync_mode      = mode,
2612                 .older_than_this = NULL,
2613                 .nr_to_write    = nr_pages * 2,
2614                 .range_start    = start,
2615                 .range_end      = end + 1,
2616         };
2617
2618         while (start <= end) {
2619                 page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
2620                 if (clear_page_dirty_for_io(page))
2621                         ret = __extent_writepage(page, &wbc_writepages, &epd);
2622                 else {
2623                         if (tree->ops && tree->ops->writepage_end_io_hook)
2624                                 tree->ops->writepage_end_io_hook(page, start,
2625                                                  start + PAGE_CACHE_SIZE - 1,
2626                                                  NULL, 1);
2627                         unlock_page(page);
2628                 }
2629                 page_cache_release(page);
2630                 start += PAGE_CACHE_SIZE;
2631         }
2632
2633         flush_epd_write_bio(&epd);
2634         return ret;
2635 }
2636
2637 int extent_writepages(struct extent_io_tree *tree,
2638                       struct address_space *mapping,
2639                       get_extent_t *get_extent,
2640                       struct writeback_control *wbc)
2641 {
2642         int ret = 0;
2643         struct extent_page_data epd = {
2644                 .bio = NULL,
2645                 .tree = tree,
2646                 .get_extent = get_extent,
2647                 .extent_locked = 0,
2648                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
2649         };
2650
2651         ret = extent_write_cache_pages(tree, mapping, wbc,
2652                                        __extent_writepage, &epd,
2653                                        flush_write_bio);
2654         flush_epd_write_bio(&epd);
2655         return ret;
2656 }
2657
2658 int extent_readpages(struct extent_io_tree *tree,
2659                      struct address_space *mapping,
2660                      struct list_head *pages, unsigned nr_pages,
2661                      get_extent_t get_extent)
2662 {
2663         struct bio *bio = NULL;
2664         unsigned page_idx;
2665         struct pagevec pvec;
2666         unsigned long bio_flags = 0;
2667
2668         pagevec_init(&pvec, 0);
2669         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
2670                 struct page *page = list_entry(pages->prev, struct page, lru);
2671
2672                 prefetchw(&page->flags);
2673                 list_del(&page->lru);
2674                 /*
2675                  * what we want to do here is call add_to_page_cache_lru,
2676                  * but that isn't exported, so we reproduce it here
2677                  */
2678                 if (!add_to_page_cache(page, mapping,
2679                                         page->index, GFP_KERNEL)) {
2680
2681                         /* open coding of lru_cache_add, also not exported */
2682                         page_cache_get(page);
2683                         if (!pagevec_add(&pvec, page))
2684                                 __pagevec_lru_add_file(&pvec);
2685                         __extent_read_full_page(tree, page, get_extent,
2686                                                 &bio, 0, &bio_flags);
2687                 }
2688                 page_cache_release(page);
2689         }
2690         if (pagevec_count(&pvec))
2691                 __pagevec_lru_add_file(&pvec);
2692         BUG_ON(!list_empty(pages));
2693         if (bio)
2694                 submit_one_bio(READ, bio, 0, bio_flags);
2695         return 0;
2696 }
2697
2698 /*
2699  * basic invalidatepage code, this waits on any locked or writeback
2700  * ranges corresponding to the page, and then deletes any extent state
2701  * records from the tree
2702  */
2703 int extent_invalidatepage(struct extent_io_tree *tree,
2704                           struct page *page, unsigned long offset)
2705 {
2706         u64 start = ((u64)page->index << PAGE_CACHE_SHIFT);
2707         u64 end = start + PAGE_CACHE_SIZE - 1;
2708         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
2709
2710         start += (offset + blocksize - 1) & ~(blocksize - 1);
2711         if (start > end)
2712                 return 0;
2713
2714         lock_extent(tree, start, end, GFP_NOFS);
2715         wait_on_page_writeback(page);
2716         clear_extent_bit(tree, start, end,
2717                          EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC,
2718                          1, 1, NULL, GFP_NOFS);
2719         return 0;
2720 }
2721
2722 /*
2723  * simple commit_write call, set_range_dirty is used to mark both
2724  * the pages and the extent records as dirty
2725  */
2726 int extent_commit_write(struct extent_io_tree *tree,
2727                         struct inode *inode, struct page *page,
2728                         unsigned from, unsigned to)
2729 {
2730         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
2731
2732         set_page_extent_mapped(page);
2733         set_page_dirty(page);
2734
2735         if (pos > inode->i_size) {
2736                 i_size_write(inode, pos);
2737                 mark_inode_dirty(inode);
2738         }
2739         return 0;
2740 }
2741
2742 int extent_prepare_write(struct extent_io_tree *tree,
2743                          struct inode *inode, struct page *page,
2744                          unsigned from, unsigned to, get_extent_t *get_extent)
2745 {
2746         u64 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2747         u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
2748         u64 block_start;
2749         u64 orig_block_start;
2750         u64 block_end;
2751         u64 cur_end;
2752         struct extent_map *em;
2753         unsigned blocksize = 1 << inode->i_blkbits;
2754         size_t page_offset = 0;
2755         size_t block_off_start;
2756         size_t block_off_end;
2757         int err = 0;
2758         int iocount = 0;
2759         int ret = 0;
2760         int isnew;
2761
2762         set_page_extent_mapped(page);
2763
2764         block_start = (page_start + from) & ~((u64)blocksize - 1);
2765         block_end = (page_start + to - 1) | (blocksize - 1);
2766         orig_block_start = block_start;
2767
2768         lock_extent(tree, page_start, page_end, GFP_NOFS);
2769         while (block_start <= block_end) {
2770                 em = get_extent(inode, page, page_offset, block_start,
2771                                 block_end - block_start + 1, 1);
2772                 if (IS_ERR(em) || !em)
2773                         goto err;
2774
2775                 cur_end = min(block_end, extent_map_end(em) - 1);
2776                 block_off_start = block_start & (PAGE_CACHE_SIZE - 1);
2777                 block_off_end = block_off_start + blocksize;
2778                 isnew = clear_extent_new(tree, block_start, cur_end, GFP_NOFS);
2779
2780                 if (!PageUptodate(page) && isnew &&
2781                     (block_off_end > to || block_off_start < from)) {
2782                         void *kaddr;
2783
2784                         kaddr = kmap_atomic(page, KM_USER0);
2785                         if (block_off_end > to)
2786                                 memset(kaddr + to, 0, block_off_end - to);
2787                         if (block_off_start < from)
2788                                 memset(kaddr + block_off_start, 0,
2789                                        from - block_off_start);
2790                         flush_dcache_page(page);
2791                         kunmap_atomic(kaddr, KM_USER0);
2792                 }
2793                 if ((em->block_start != EXTENT_MAP_HOLE &&
2794                      em->block_start != EXTENT_MAP_INLINE) &&
2795                     !isnew && !PageUptodate(page) &&
2796                     (block_off_end > to || block_off_start < from) &&
2797                     !test_range_bit(tree, block_start, cur_end,
2798                                     EXTENT_UPTODATE, 1, NULL)) {
2799                         u64 sector;
2800                         u64 extent_offset = block_start - em->start;
2801                         size_t iosize;
2802                         sector = (em->block_start + extent_offset) >> 9;
2803                         iosize = (cur_end - block_start + blocksize) &
2804                                 ~((u64)blocksize - 1);
2805                         /*
2806                          * we've already got the extent locked, but we
2807                          * need to split the state such that our end_bio
2808                          * handler can clear the lock.
2809                          */
2810                         set_extent_bit(tree, block_start,
2811                                        block_start + iosize - 1,
2812                                        EXTENT_LOCKED, 0, NULL, NULL, GFP_NOFS);
2813                         ret = submit_extent_page(READ, tree, page,
2814                                          sector, iosize, page_offset, em->bdev,
2815                                          NULL, 1,
2816                                          end_bio_extent_preparewrite, 0,
2817                                          0, 0);
2818                         iocount++;
2819                         block_start = block_start + iosize;
2820                 } else {
2821                         set_extent_uptodate(tree, block_start, cur_end,
2822                                             GFP_NOFS);
2823                         unlock_extent(tree, block_start, cur_end, GFP_NOFS);
2824                         block_start = cur_end + 1;
2825                 }
2826                 page_offset = block_start & (PAGE_CACHE_SIZE - 1);
2827                 free_extent_map(em);
2828         }
2829         if (iocount) {
2830                 wait_extent_bit(tree, orig_block_start,
2831                                 block_end, EXTENT_LOCKED);
2832         }
2833         check_page_uptodate(tree, page);
2834 err:
2835         /* FIXME, zero out newly allocated blocks on error */
2836         return err;
2837 }
2838
2839 /*
2840  * a helper for releasepage, this tests for areas of the page that
2841  * are locked or under IO and drops the related state bits if it is safe
2842  * to drop the page.
2843  */
2844 int try_release_extent_state(struct extent_map_tree *map,
2845                              struct extent_io_tree *tree, struct page *page,
2846                              gfp_t mask)
2847 {
2848         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2849         u64 end = start + PAGE_CACHE_SIZE - 1;
2850         int ret = 1;
2851
2852         if (test_range_bit(tree, start, end,
2853                            EXTENT_IOBITS, 0, NULL))
2854                 ret = 0;
2855         else {
2856                 if ((mask & GFP_NOFS) == GFP_NOFS)
2857                         mask = GFP_NOFS;
2858                 /*
2859                  * at this point we can safely clear everything except the
2860                  * locked bit and the nodatasum bit
2861                  */
2862                 clear_extent_bit(tree, start, end,
2863                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
2864                                  0, 0, NULL, mask);
2865         }
2866         return ret;
2867 }
2868
2869 /*
2870  * a helper for releasepage.  As long as there are no locked extents
2871  * in the range corresponding to the page, both state records and extent
2872  * map records are removed
2873  */
2874 int try_release_extent_mapping(struct extent_map_tree *map,
2875                                struct extent_io_tree *tree, struct page *page,
2876                                gfp_t mask)
2877 {
2878         struct extent_map *em;
2879         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2880         u64 end = start + PAGE_CACHE_SIZE - 1;
2881
2882         if ((mask & __GFP_WAIT) &&
2883             page->mapping->host->i_size > 16 * 1024 * 1024) {
2884                 u64 len;
2885                 while (start <= end) {
2886                         len = end - start + 1;
2887                         write_lock(&map->lock);
2888                         em = lookup_extent_mapping(map, start, len);
2889                         if (!em || IS_ERR(em)) {
2890                                 write_unlock(&map->lock);
2891                                 break;
2892                         }
2893                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
2894                             em->start != start) {
2895                                 write_unlock(&map->lock);
2896                                 free_extent_map(em);
2897                                 break;
2898                         }
2899                         if (!test_range_bit(tree, em->start,
2900                                             extent_map_end(em) - 1,
2901                                             EXTENT_LOCKED | EXTENT_WRITEBACK,
2902                                             0, NULL)) {
2903                                 remove_extent_mapping(map, em);
2904                                 /* once for the rb tree */
2905                                 free_extent_map(em);
2906                         }
2907                         start = extent_map_end(em);
2908                         write_unlock(&map->lock);
2909
2910                         /* once for us */
2911                         free_extent_map(em);
2912                 }
2913         }
2914         return try_release_extent_state(map, tree, page, mask);
2915 }
2916
2917 sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
2918                 get_extent_t *get_extent)
2919 {
2920         struct inode *inode = mapping->host;
2921         u64 start = iblock << inode->i_blkbits;
2922         sector_t sector = 0;
2923         size_t blksize = (1 << inode->i_blkbits);
2924         struct extent_map *em;
2925
2926         lock_extent(&BTRFS_I(inode)->io_tree, start, start + blksize - 1,
2927                     GFP_NOFS);
2928         em = get_extent(inode, NULL, 0, start, blksize, 0);
2929         unlock_extent(&BTRFS_I(inode)->io_tree, start, start + blksize - 1,
2930                       GFP_NOFS);
2931         if (!em || IS_ERR(em))
2932                 return 0;
2933
2934         if (em->block_start > EXTENT_MAP_LAST_BYTE)
2935                 goto out;
2936
2937         sector = (em->block_start + start - em->start) >> inode->i_blkbits;
2938 out:
2939         free_extent_map(em);
2940         return sector;
2941 }
2942
2943 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
2944                 __u64 start, __u64 len, get_extent_t *get_extent)
2945 {
2946         int ret;
2947         u64 off = start;
2948         u64 max = start + len;
2949         u32 flags = 0;
2950         u64 disko = 0;
2951         struct extent_map *em = NULL;
2952         int end = 0;
2953         u64 em_start = 0, em_len = 0;
2954         unsigned long emflags;
2955         ret = 0;
2956
2957         if (len == 0)
2958                 return -EINVAL;
2959
2960         lock_extent(&BTRFS_I(inode)->io_tree, start, start + len,
2961                 GFP_NOFS);
2962         em = get_extent(inode, NULL, 0, off, max - off, 0);
2963         if (!em)
2964                 goto out;
2965         if (IS_ERR(em)) {
2966                 ret = PTR_ERR(em);
2967                 goto out;
2968         }
2969         while (!end) {
2970                 off = em->start + em->len;
2971                 if (off >= max)
2972                         end = 1;
2973
2974                 em_start = em->start;
2975                 em_len = em->len;
2976
2977                 disko = 0;
2978                 flags = 0;
2979
2980                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
2981                         end = 1;
2982                         flags |= FIEMAP_EXTENT_LAST;
2983                 } else if (em->block_start == EXTENT_MAP_HOLE) {
2984                         flags |= FIEMAP_EXTENT_UNWRITTEN;
2985                 } else if (em->block_start == EXTENT_MAP_INLINE) {
2986                         flags |= (FIEMAP_EXTENT_DATA_INLINE |
2987                                   FIEMAP_EXTENT_NOT_ALIGNED);
2988                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
2989                         flags |= (FIEMAP_EXTENT_DELALLOC |
2990                                   FIEMAP_EXTENT_UNKNOWN);
2991                 } else {
2992                         disko = em->block_start;
2993                 }
2994                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
2995                         flags |= FIEMAP_EXTENT_ENCODED;
2996
2997                 emflags = em->flags;
2998                 free_extent_map(em);
2999                 em = NULL;
3000
3001                 if (!end) {
3002                         em = get_extent(inode, NULL, 0, off, max - off, 0);
3003                         if (!em)
3004                                 goto out;
3005                         if (IS_ERR(em)) {
3006                                 ret = PTR_ERR(em);
3007                                 goto out;
3008                         }
3009                         emflags = em->flags;
3010                 }
3011                 if (test_bit(EXTENT_FLAG_VACANCY, &emflags)) {
3012                         flags |= FIEMAP_EXTENT_LAST;
3013                         end = 1;
3014                 }
3015
3016                 ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
3017                                         em_len, flags);
3018                 if (ret)
3019                         goto out_free;
3020         }
3021 out_free:
3022         free_extent_map(em);
3023 out:
3024         unlock_extent(&BTRFS_I(inode)->io_tree, start, start + len,
3025                         GFP_NOFS);
3026         return ret;
3027 }
3028
3029 static inline struct page *extent_buffer_page(struct extent_buffer *eb,
3030                                               unsigned long i)
3031 {
3032         struct page *p;
3033         struct address_space *mapping;
3034
3035         if (i == 0)
3036                 return eb->first_page;
3037         i += eb->start >> PAGE_CACHE_SHIFT;
3038         mapping = eb->first_page->mapping;
3039         if (!mapping)
3040                 return NULL;
3041
3042         /*
3043          * extent_buffer_page is only called after pinning the page
3044          * by increasing the reference count.  So we know the page must
3045          * be in the radix tree.
3046          */
3047         rcu_read_lock();
3048         p = radix_tree_lookup(&mapping->page_tree, i);
3049         rcu_read_unlock();
3050
3051         return p;
3052 }
3053
3054 static inline unsigned long num_extent_pages(u64 start, u64 len)
3055 {
3056         return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
3057                 (start >> PAGE_CACHE_SHIFT);
3058 }
3059
3060 static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
3061                                                    u64 start,
3062                                                    unsigned long len,
3063                                                    gfp_t mask)
3064 {
3065         struct extent_buffer *eb = NULL;
3066 #if LEAK_DEBUG
3067         unsigned long flags;
3068 #endif
3069
3070         eb = kmem_cache_zalloc(extent_buffer_cache, mask);
3071         eb->start = start;
3072         eb->len = len;
3073         spin_lock_init(&eb->lock);
3074         init_waitqueue_head(&eb->lock_wq);
3075
3076 #if LEAK_DEBUG
3077         spin_lock_irqsave(&leak_lock, flags);
3078         list_add(&eb->leak_list, &buffers);
3079         spin_unlock_irqrestore(&leak_lock, flags);
3080 #endif
3081         atomic_set(&eb->refs, 1);
3082
3083         return eb;
3084 }
3085
3086 static void __free_extent_buffer(struct extent_buffer *eb)
3087 {
3088 #if LEAK_DEBUG
3089         unsigned long flags;
3090         spin_lock_irqsave(&leak_lock, flags);
3091         list_del(&eb->leak_list);
3092         spin_unlock_irqrestore(&leak_lock, flags);
3093 #endif
3094         kmem_cache_free(extent_buffer_cache, eb);
3095 }
3096
3097 struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
3098                                           u64 start, unsigned long len,
3099                                           struct page *page0,
3100                                           gfp_t mask)
3101 {
3102         unsigned long num_pages = num_extent_pages(start, len);
3103         unsigned long i;
3104         unsigned long index = start >> PAGE_CACHE_SHIFT;
3105         struct extent_buffer *eb;
3106         struct extent_buffer *exists = NULL;
3107         struct page *p;
3108         struct address_space *mapping = tree->mapping;
3109         int uptodate = 1;
3110
3111         spin_lock(&tree->buffer_lock);
3112         eb = buffer_search(tree, start);
3113         if (eb) {
3114                 atomic_inc(&eb->refs);
3115                 spin_unlock(&tree->buffer_lock);
3116                 mark_page_accessed(eb->first_page);
3117                 return eb;
3118         }
3119         spin_unlock(&tree->buffer_lock);
3120
3121         eb = __alloc_extent_buffer(tree, start, len, mask);
3122         if (!eb)
3123                 return NULL;
3124
3125         if (page0) {
3126                 eb->first_page = page0;
3127                 i = 1;
3128                 index++;
3129                 page_cache_get(page0);
3130                 mark_page_accessed(page0);
3131                 set_page_extent_mapped(page0);
3132                 set_page_extent_head(page0, len);
3133                 uptodate = PageUptodate(page0);
3134         } else {
3135                 i = 0;
3136         }
3137         for (; i < num_pages; i++, index++) {
3138                 p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
3139                 if (!p) {
3140                         WARN_ON(1);
3141                         goto free_eb;
3142                 }
3143                 set_page_extent_mapped(p);
3144                 mark_page_accessed(p);
3145                 if (i == 0) {
3146                         eb->first_page = p;
3147                         set_page_extent_head(p, len);
3148                 } else {
3149                         set_page_private(p, EXTENT_PAGE_PRIVATE);
3150                 }
3151                 if (!PageUptodate(p))
3152                         uptodate = 0;
3153                 unlock_page(p);
3154         }
3155         if (uptodate)
3156                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3157
3158         spin_lock(&tree->buffer_lock);
3159         exists = buffer_tree_insert(tree, start, &eb->rb_node);
3160         if (exists) {
3161                 /* add one reference for the caller */
3162                 atomic_inc(&exists->refs);
3163                 spin_unlock(&tree->buffer_lock);
3164                 goto free_eb;
3165         }
3166         spin_unlock(&tree->buffer_lock);
3167
3168         /* add one reference for the tree */
3169         atomic_inc(&eb->refs);
3170         return eb;
3171
3172 free_eb:
3173         if (!atomic_dec_and_test(&eb->refs))
3174                 return exists;
3175         for (index = 1; index < i; index++)
3176                 page_cache_release(extent_buffer_page(eb, index));
3177         page_cache_release(extent_buffer_page(eb, 0));
3178         __free_extent_buffer(eb);
3179         return exists;
3180 }
3181
3182 struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
3183                                          u64 start, unsigned long len,
3184                                           gfp_t mask)
3185 {
3186         struct extent_buffer *eb;
3187
3188         spin_lock(&tree->buffer_lock);
3189         eb = buffer_search(tree, start);
3190         if (eb)
3191                 atomic_inc(&eb->refs);
3192         spin_unlock(&tree->buffer_lock);
3193
3194         if (eb)
3195                 mark_page_accessed(eb->first_page);
3196
3197         return eb;
3198 }
3199
3200 void free_extent_buffer(struct extent_buffer *eb)
3201 {
3202         if (!eb)
3203                 return;
3204
3205         if (!atomic_dec_and_test(&eb->refs))
3206                 return;
3207
3208         WARN_ON(1);
3209 }
3210
3211 int clear_extent_buffer_dirty(struct extent_io_tree *tree,
3212                               struct extent_buffer *eb)
3213 {
3214         unsigned long i;
3215         unsigned long num_pages;
3216         struct page *page;
3217
3218         num_pages = num_extent_pages(eb->start, eb->len);
3219
3220         for (i = 0; i < num_pages; i++) {
3221                 page = extent_buffer_page(eb, i);
3222                 if (!PageDirty(page))
3223                         continue;
3224
3225                 lock_page(page);
3226                 if (i == 0)
3227                         set_page_extent_head(page, eb->len);
3228                 else
3229                         set_page_private(page, EXTENT_PAGE_PRIVATE);
3230
3231                 clear_page_dirty_for_io(page);
3232                 spin_lock_irq(&page->mapping->tree_lock);
3233                 if (!PageDirty(page)) {
3234                         radix_tree_tag_clear(&page->mapping->page_tree,
3235                                                 page_index(page),
3236                                                 PAGECACHE_TAG_DIRTY);
3237                 }
3238                 spin_unlock_irq(&page->mapping->tree_lock);
3239                 unlock_page(page);
3240         }
3241         return 0;
3242 }
3243
3244 int wait_on_extent_buffer_writeback(struct extent_io_tree *tree,
3245                                     struct extent_buffer *eb)
3246 {
3247         return wait_on_extent_writeback(tree, eb->start,
3248                                         eb->start + eb->len - 1);
3249 }
3250
3251 int set_extent_buffer_dirty(struct extent_io_tree *tree,
3252                              struct extent_buffer *eb)
3253 {
3254         unsigned long i;
3255         unsigned long num_pages;
3256         int was_dirty = 0;
3257
3258         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
3259         num_pages = num_extent_pages(eb->start, eb->len);
3260         for (i = 0; i < num_pages; i++)
3261                 __set_page_dirty_nobuffers(extent_buffer_page(eb, i));
3262         return was_dirty;
3263 }
3264
3265 int clear_extent_buffer_uptodate(struct extent_io_tree *tree,
3266                                 struct extent_buffer *eb)
3267 {
3268         unsigned long i;
3269         struct page *page;
3270         unsigned long num_pages;
3271
3272         num_pages = num_extent_pages(eb->start, eb->len);
3273         clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3274
3275         clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
3276                               GFP_NOFS);
3277         for (i = 0; i < num_pages; i++) {
3278                 page = extent_buffer_page(eb, i);
3279                 if (page)
3280                         ClearPageUptodate(page);
3281         }
3282         return 0;
3283 }
3284
3285 int set_extent_buffer_uptodate(struct extent_io_tree *tree,
3286                                 struct extent_buffer *eb)
3287 {
3288         unsigned long i;
3289         struct page *page;
3290         unsigned long num_pages;
3291
3292         num_pages = num_extent_pages(eb->start, eb->len);
3293
3294         set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
3295                             GFP_NOFS);
3296         for (i = 0; i < num_pages; i++) {
3297                 page = extent_buffer_page(eb, i);
3298                 if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
3299                     ((i == num_pages - 1) &&
3300                      ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
3301                         check_page_uptodate(tree, page);
3302                         continue;
3303                 }
3304                 SetPageUptodate(page);
3305         }
3306         return 0;
3307 }
3308
3309 int extent_range_uptodate(struct extent_io_tree *tree,
3310                           u64 start, u64 end)
3311 {
3312         struct page *page;
3313         int ret;
3314         int pg_uptodate = 1;
3315         int uptodate;
3316         unsigned long index;
3317
3318         ret = test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL);
3319         if (ret)
3320                 return 1;
3321         while (start <= end) {
3322                 index = start >> PAGE_CACHE_SHIFT;
3323                 page = find_get_page(tree->mapping, index);
3324                 uptodate = PageUptodate(page);
3325                 page_cache_release(page);
3326                 if (!uptodate) {
3327                         pg_uptodate = 0;
3328                         break;
3329                 }
3330                 start += PAGE_CACHE_SIZE;
3331         }
3332         return pg_uptodate;
3333 }
3334
3335 int extent_buffer_uptodate(struct extent_io_tree *tree,
3336                            struct extent_buffer *eb)
3337 {
3338         int ret = 0;
3339         unsigned long num_pages;
3340         unsigned long i;
3341         struct page *page;
3342         int pg_uptodate = 1;
3343
3344         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
3345                 return 1;
3346
3347         ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1,
3348                            EXTENT_UPTODATE, 1, NULL);
3349         if (ret)
3350                 return ret;
3351
3352         num_pages = num_extent_pages(eb->start, eb->len);
3353         for (i = 0; i < num_pages; i++) {
3354                 page = extent_buffer_page(eb, i);
3355                 if (!PageUptodate(page)) {
3356                         pg_uptodate = 0;
3357                         break;
3358                 }
3359         }
3360         return pg_uptodate;
3361 }
3362
3363 int read_extent_buffer_pages(struct extent_io_tree *tree,
3364                              struct extent_buffer *eb,
3365                              u64 start, int wait,
3366                              get_extent_t *get_extent, int mirror_num)
3367 {
3368         unsigned long i;
3369         unsigned long start_i;
3370         struct page *page;
3371         int err;
3372         int ret = 0;
3373         int locked_pages = 0;
3374         int all_uptodate = 1;
3375         int inc_all_pages = 0;
3376         unsigned long num_pages;
3377         struct bio *bio = NULL;
3378         unsigned long bio_flags = 0;
3379
3380         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
3381                 return 0;
3382
3383         if (test_range_bit(tree, eb->start, eb->start + eb->len - 1,
3384                            EXTENT_UPTODATE, 1, NULL)) {
3385                 return 0;
3386         }
3387
3388         if (start) {
3389                 WARN_ON(start < eb->start);
3390                 start_i = (start >> PAGE_CACHE_SHIFT) -
3391                         (eb->start >> PAGE_CACHE_SHIFT);
3392         } else {
3393                 start_i = 0;
3394         }
3395
3396         num_pages = num_extent_pages(eb->start, eb->len);
3397         for (i = start_i; i < num_pages; i++) {
3398                 page = extent_buffer_page(eb, i);
3399                 if (!wait) {
3400                         if (!trylock_page(page))
3401                                 goto unlock_exit;
3402                 } else {
3403                         lock_page(page);
3404                 }
3405                 locked_pages++;
3406                 if (!PageUptodate(page))
3407                         all_uptodate = 0;
3408         }
3409         if (all_uptodate) {
3410                 if (start_i == 0)
3411                         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3412                 goto unlock_exit;
3413         }
3414
3415         for (i = start_i; i < num_pages; i++) {
3416                 page = extent_buffer_page(eb, i);
3417                 if (inc_all_pages)
3418                         page_cache_get(page);
3419                 if (!PageUptodate(page)) {
3420                         if (start_i == 0)
3421                                 inc_all_pages = 1;
3422                         ClearPageError(page);
3423                         err = __extent_read_full_page(tree, page,
3424                                                       get_extent, &bio,
3425                                                       mirror_num, &bio_flags);
3426                         if (err)
3427                                 ret = err;
3428                 } else {
3429                         unlock_page(page);
3430                 }
3431         }
3432
3433         if (bio)
3434                 submit_one_bio(READ, bio, mirror_num, bio_flags);
3435
3436         if (ret || !wait)
3437                 return ret;
3438
3439         for (i = start_i; i < num_pages; i++) {
3440                 page = extent_buffer_page(eb, i);
3441                 wait_on_page_locked(page);
3442                 if (!PageUptodate(page))
3443                         ret = -EIO;
3444         }
3445
3446         if (!ret)
3447                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3448         return ret;
3449
3450 unlock_exit:
3451         i = start_i;
3452         while (locked_pages > 0) {
3453                 page = extent_buffer_page(eb, i);
3454                 i++;
3455                 unlock_page(page);
3456                 locked_pages--;
3457         }
3458         return ret;
3459 }
3460
3461 void read_extent_buffer(struct extent_buffer *eb, void *dstv,
3462                         unsigned long start,
3463                         unsigned long len)
3464 {
3465         size_t cur;
3466         size_t offset;
3467         struct page *page;
3468         char *kaddr;
3469         char *dst = (char *)dstv;
3470         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3471         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3472
3473         WARN_ON(start > eb->len);
3474         WARN_ON(start + len > eb->start + eb->len);
3475
3476         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3477
3478         while (len > 0) {
3479                 page = extent_buffer_page(eb, i);
3480
3481                 cur = min(len, (PAGE_CACHE_SIZE - offset));
3482                 kaddr = kmap_atomic(page, KM_USER1);
3483                 memcpy(dst, kaddr + offset, cur);
3484                 kunmap_atomic(kaddr, KM_USER1);
3485
3486                 dst += cur;
3487                 len -= cur;
3488                 offset = 0;
3489                 i++;
3490         }
3491 }
3492
3493 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
3494                                unsigned long min_len, char **token, char **map,
3495                                unsigned long *map_start,
3496                                unsigned long *map_len, int km)
3497 {
3498         size_t offset = start & (PAGE_CACHE_SIZE - 1);
3499         char *kaddr;
3500         struct page *p;
3501         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3502         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3503         unsigned long end_i = (start_offset + start + min_len - 1) >>
3504                 PAGE_CACHE_SHIFT;
3505
3506         if (i != end_i)
3507                 return -EINVAL;
3508
3509         if (i == 0) {
3510                 offset = start_offset;
3511                 *map_start = 0;
3512         } else {
3513                 offset = 0;
3514                 *map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset;
3515         }
3516
3517         if (start + min_len > eb->len) {
3518                 printk(KERN_ERR "btrfs bad mapping eb start %llu len %lu, "
3519                        "wanted %lu %lu\n", (unsigned long long)eb->start,
3520                        eb->len, start, min_len);
3521                 WARN_ON(1);
3522         }
3523
3524         p = extent_buffer_page(eb, i);
3525         kaddr = kmap_atomic(p, km);
3526         *token = kaddr;
3527         *map = kaddr + offset;
3528         *map_len = PAGE_CACHE_SIZE - offset;
3529         return 0;
3530 }
3531
3532 int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
3533                       unsigned long min_len,
3534                       char **token, char **map,
3535                       unsigned long *map_start,
3536                       unsigned long *map_len, int km)
3537 {
3538         int err;
3539         int save = 0;
3540         if (eb->map_token) {
3541                 unmap_extent_buffer(eb, eb->map_token, km);
3542                 eb->map_token = NULL;
3543                 save = 1;
3544         }
3545         err = map_private_extent_buffer(eb, start, min_len, token, map,
3546                                        map_start, map_len, km);
3547         if (!err && save) {
3548                 eb->map_token = *token;
3549                 eb->kaddr = *map;
3550                 eb->map_start = *map_start;
3551                 eb->map_len = *map_len;
3552         }
3553         return err;
3554 }
3555
3556 void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km)
3557 {
3558         kunmap_atomic(token, km);
3559 }
3560
3561 int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
3562                           unsigned long start,
3563                           unsigned long len)
3564 {
3565         size_t cur;
3566         size_t offset;
3567         struct page *page;
3568         char *kaddr;
3569         char *ptr = (char *)ptrv;
3570         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3571         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3572         int ret = 0;
3573
3574         WARN_ON(start > eb->len);
3575         WARN_ON(start + len > eb->start + eb->len);
3576
3577         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3578
3579         while (len > 0) {
3580                 page = extent_buffer_page(eb, i);
3581
3582                 cur = min(len, (PAGE_CACHE_SIZE - offset));
3583
3584                 kaddr = kmap_atomic(page, KM_USER0);
3585                 ret = memcmp(ptr, kaddr + offset, cur);
3586                 kunmap_atomic(kaddr, KM_USER0);
3587                 if (ret)
3588                         break;
3589
3590                 ptr += cur;
3591                 len -= cur;
3592                 offset = 0;
3593                 i++;
3594         }
3595         return ret;
3596 }
3597
3598 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
3599                          unsigned long start, unsigned long len)
3600 {
3601         size_t cur;
3602         size_t offset;
3603         struct page *page;
3604         char *kaddr;
3605         char *src = (char *)srcv;
3606         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3607         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3608
3609         WARN_ON(start > eb->len);
3610         WARN_ON(start + len > eb->start + eb->len);
3611
3612         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3613
3614         while (len > 0) {
3615                 page = extent_buffer_page(eb, i);
3616                 WARN_ON(!PageUptodate(page));
3617
3618                 cur = min(len, PAGE_CACHE_SIZE - offset);
3619                 kaddr = kmap_atomic(page, KM_USER1);
3620                 memcpy(kaddr + offset, src, cur);
3621                 kunmap_atomic(kaddr, KM_USER1);
3622
3623                 src += cur;
3624                 len -= cur;
3625                 offset = 0;
3626                 i++;
3627         }
3628 }
3629
3630 void memset_extent_buffer(struct extent_buffer *eb, char c,
3631                           unsigned long start, unsigned long len)
3632 {
3633         size_t cur;
3634         size_t offset;
3635         struct page *page;
3636         char *kaddr;
3637         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3638         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3639
3640         WARN_ON(start > eb->len);
3641         WARN_ON(start + len > eb->start + eb->len);
3642
3643         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3644
3645         while (len > 0) {
3646                 page = extent_buffer_page(eb, i);
3647                 WARN_ON(!PageUptodate(page));
3648
3649                 cur = min(len, PAGE_CACHE_SIZE - offset);
3650                 kaddr = kmap_atomic(page, KM_USER0);
3651                 memset(kaddr + offset, c, cur);
3652                 kunmap_atomic(kaddr, KM_USER0);
3653
3654                 len -= cur;
3655                 offset = 0;
3656                 i++;
3657         }
3658 }
3659
3660 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
3661                         unsigned long dst_offset, unsigned long src_offset,
3662                         unsigned long len)
3663 {
3664         u64 dst_len = dst->len;
3665         size_t cur;
3666         size_t offset;
3667         struct page *page;
3668         char *kaddr;
3669         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3670         unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
3671
3672         WARN_ON(src->len != dst_len);
3673
3674         offset = (start_offset + dst_offset) &
3675                 ((unsigned long)PAGE_CACHE_SIZE - 1);
3676
3677         while (len > 0) {
3678                 page = extent_buffer_page(dst, i);
3679                 WARN_ON(!PageUptodate(page));
3680
3681                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
3682
3683                 kaddr = kmap_atomic(page, KM_USER0);
3684                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
3685                 kunmap_atomic(kaddr, KM_USER0);
3686
3687                 src_offset += cur;
3688                 len -= cur;
3689                 offset = 0;
3690                 i++;
3691         }
3692 }
3693
3694 static void move_pages(struct page *dst_page, struct page *src_page,
3695                        unsigned long dst_off, unsigned long src_off,
3696                        unsigned long len)
3697 {
3698         char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
3699         if (dst_page == src_page) {
3700                 memmove(dst_kaddr + dst_off, dst_kaddr + src_off, len);
3701         } else {
3702                 char *src_kaddr = kmap_atomic(src_page, KM_USER1);
3703                 char *p = dst_kaddr + dst_off + len;
3704                 char *s = src_kaddr + src_off + len;
3705
3706                 while (len--)
3707                         *--p = *--s;
3708
3709                 kunmap_atomic(src_kaddr, KM_USER1);
3710         }
3711         kunmap_atomic(dst_kaddr, KM_USER0);
3712 }
3713
3714 static void copy_pages(struct page *dst_page, struct page *src_page,
3715                        unsigned long dst_off, unsigned long src_off,
3716                        unsigned long len)
3717 {
3718         char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
3719         char *src_kaddr;
3720
3721         if (dst_page != src_page)
3722                 src_kaddr = kmap_atomic(src_page, KM_USER1);
3723         else
3724                 src_kaddr = dst_kaddr;
3725
3726         memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
3727         kunmap_atomic(dst_kaddr, KM_USER0);
3728         if (dst_page != src_page)
3729                 kunmap_atomic(src_kaddr, KM_USER1);
3730 }
3731
3732 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
3733                            unsigned long src_offset, unsigned long len)
3734 {
3735         size_t cur;
3736         size_t dst_off_in_page;
3737         size_t src_off_in_page;
3738         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3739         unsigned long dst_i;
3740         unsigned long src_i;
3741
3742         if (src_offset + len > dst->len) {
3743                 printk(KERN_ERR "btrfs memmove bogus src_offset %lu move "
3744                        "len %lu dst len %lu\n", src_offset, len, dst->len);
3745                 BUG_ON(1);
3746         }
3747         if (dst_offset + len > dst->len) {
3748                 printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move "
3749                        "len %lu dst len %lu\n", dst_offset, len, dst->len);
3750                 BUG_ON(1);
3751         }
3752
3753         while (len > 0) {
3754                 dst_off_in_page = (start_offset + dst_offset) &
3755                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3756                 src_off_in_page = (start_offset + src_offset) &
3757                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3758
3759                 dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
3760                 src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT;
3761
3762                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE -
3763                                                src_off_in_page));
3764                 cur = min_t(unsigned long, cur,
3765                         (unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page));
3766
3767                 copy_pages(extent_buffer_page(dst, dst_i),
3768                            extent_buffer_page(dst, src_i),
3769                            dst_off_in_page, src_off_in_page, cur);
3770
3771                 src_offset += cur;
3772                 dst_offset += cur;
3773                 len -= cur;
3774         }
3775 }
3776
3777 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
3778                            unsigned long src_offset, unsigned long len)
3779 {
3780         size_t cur;
3781         size_t dst_off_in_page;
3782         size_t src_off_in_page;
3783         unsigned long dst_end = dst_offset + len - 1;
3784         unsigned long src_end = src_offset + len - 1;
3785         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3786         unsigned long dst_i;
3787         unsigned long src_i;
3788
3789         if (src_offset + len > dst->len) {
3790                 printk(KERN_ERR "btrfs memmove bogus src_offset %lu move "
3791                        "len %lu len %lu\n", src_offset, len, dst->len);
3792                 BUG_ON(1);
3793         }
3794         if (dst_offset + len > dst->len) {
3795                 printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move "
3796                        "len %lu len %lu\n", dst_offset, len, dst->len);
3797                 BUG_ON(1);
3798         }
3799         if (dst_offset < src_offset) {
3800                 memcpy_extent_buffer(dst, dst_offset, src_offset, len);
3801                 return;
3802         }
3803         while (len > 0) {
3804                 dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT;
3805                 src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT;
3806
3807                 dst_off_in_page = (start_offset + dst_end) &
3808                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3809                 src_off_in_page = (start_offset + src_end) &
3810                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3811
3812                 cur = min_t(unsigned long, len, src_off_in_page + 1);
3813                 cur = min(cur, dst_off_in_page + 1);
3814                 move_pages(extent_buffer_page(dst, dst_i),
3815                            extent_buffer_page(dst, src_i),
3816                            dst_off_in_page - cur + 1,
3817                            src_off_in_page - cur + 1, cur);
3818
3819                 dst_end -= cur;
3820                 src_end -= cur;
3821                 len -= cur;
3822         }
3823 }
3824
3825 int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
3826 {
3827         u64 start = page_offset(page);
3828         struct extent_buffer *eb;
3829         int ret = 1;
3830         unsigned long i;
3831         unsigned long num_pages;
3832
3833         spin_lock(&tree->buffer_lock);
3834         eb = buffer_search(tree, start);
3835         if (!eb)
3836                 goto out;
3837
3838         if (atomic_read(&eb->refs) > 1) {
3839                 ret = 0;
3840                 goto out;
3841         }
3842         if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
3843                 ret = 0;
3844                 goto out;
3845         }
3846         /* at this point we can safely release the extent buffer */
3847         num_pages = num_extent_pages(eb->start, eb->len);
3848         for (i = 0; i < num_pages; i++)
3849                 page_cache_release(extent_buffer_page(eb, i));
3850         rb_erase(&eb->rb_node, &tree->buffer);
3851         __free_extent_buffer(eb);
3852 out:
3853         spin_unlock(&tree->buffer_lock);
3854         return ret;
3855 }